14.5.2001

Nicht alles, was in der Natur wächst, kann der Mensch essen. Gifte in Pflanzen und Tieren und Pilzen gehören zu den natürlichen Abwehrstoffen, mit denen sich diese Lebewesen gegen ihre Freßfeinde und Nahrungskonkurrenten durchsetzen.

Algen gehören zu den verbreitetsten Lebewesen auf der Erde. Einige sind für den Menschen sehr giftig, entweder sie selbst direkt oder indirekt durch die von ihnen produzierten Stoffwechselprodukte.

Eine weitere Quelle für Gifte können aber auch aufgenommene Stoffe aus der Umwelt sein (vor allem Schwermetalle) und andere Lebewesen, die in, an oder mit den Algen leben.

Algen lassen sich sehr leicht züchten bzw ernten. Mit den entsprechenden Werbelügen angepriesen, werden sie vor allem an Kranke in anderen Ländern verkauft.

Zu den bekanntesten Algen im Gesundheitsmarkt gehören die "chlorella pyrenoidosa" und die "Blau-grün-Algen aus dem Lake Klamath" ("blue-green algae (BGA)") in den USA.

Obwohl die chlorella pyrenoidosa angeblich die am schnellsten wachsende Pflanze der Erde ist, wird sie verkauft zum Preis von 500 DM pro Kilogramm, das heißt zum 500-fachen des Preises von Getreidemehl.

Helfen sollen die Algen gegen Schwermetallvergiftungen, ADS (Hyperaktivität, ADHD), und alles mögliche und unmögliche andere. Den Beweis für die Wirksamkeit der Algen bleiben die Verkäufer schuldig. Oder sie lügen das Blaue vom Himmel herunter.

In der amerikanischen "PubMed" sind über Algen und Gifte brauchbare Fundstellen aufgelistet. Ich habe 171 abstracts bzw Hinweise gefunden als weitere Quellen zu dem hier als Nr. 1 genannten Beitrag.

Aribert Deckers

Journal Citations:

Item 1 displayed (out of 171 found).

Assessing potential health risks from microcystin toxins in blue-green algae dietary supplements.

Gilroy DJ, Kauffman KW, Hall RA, Huang X, Chu FS.

Environmental Services and Consultation Section, Oregon Health Division, Portland, Oregon 97232, USA. duncan.j.gilroy@state.or.us

The presence of blue-green algae (BGA) toxins in surface waters used for drinking water sources and recreation is receiving increasing attention around the world as a public health concern. However, potential risks from exposure to these toxins in contaminated health food products that contain BGA have been largely ignored. BGA products are commonly consumed in the United States, Canada, and Europe for their putative beneficial effects, including increased energy and elevated mood. Many of these products contain Aphanizomenon flos-aquae, a BGA that is harvested from Upper Klamath Lake (UKL) in southern Oregon, where the growth of a toxic BGA, Microcystis aeruginosa, is a regular occurrence. M. aeruginosa produces compounds called microcystins, which are potent hepatotoxins and probable tumor promoters. Because M. aeruginosa coexists with A. flos-aquae, it can be collected inadvertently during the harvesting process, resulting in microcystin contamination of BGA products. In fall 1996, the Oregon Health Division learned that UKL was experiencing an extensive M. aeruginosa bloom, and an advisory was issued recommending against water contact. The advisory prompted calls from consumers of BGA products, who expressed concern about possible contamination of these products with microcystins. In response, the Oregon Health Division and the Oregon Department of Agriculture established a regulatory limit of 1 microg/g for microcystins in BGA-containing products and tested BGA products for the presence of microcystins. Microcystins were detected in 85 of 87 samples tested, with 63 samples (72%) containing concentrations > 1 microg/g. HPLC and ELISA tentatively identified microcystin-LR, the most toxic microcystin variant, as the predominant congener.

PMID: 10811570
From PubMed

Risk assessment of microcystin in dietary Aphanizomenon flos-aquae.

Schaeffer DJ, Malpas PB, Barton LL.

Department of Veterinary Biosciences, University of Illinois, 2001 South Lincoln Avenue, Urbana, Illinois 61802, USA.

Aphanizomenon flos-aquae, a cyanobacterium that is marketed as a health food supplement, is harvested from natural blooms in Klamath Lake (Oregon) that are occasionally contaminated by Microcystis spp. Regulatory agencies in several countries are developing regulations to control the amount of microcystin in drinking water and other products, including products produced from A. flos-aquae. Regulation of microcystin (MC), a toxin produced by Microcystis spp. that is potentially present in natural culture of A. flos-aquae, should be based on studies in which a test species is exposed to the natural mixture of these cyanobacteria. A 1984 feeding trial to determine the effects of high dietary levels of A. flos-aquae on reproduction and development of mice is reanalyzed in light of recent analyses for microcystin-LR (MCLR) in the diets of those mice. Young adult mice consuming up to 333 microg MCLR/kg body weight (bw)/day exhibited no adverse effects on growth and reproduction, fetal development, and survival and organ weights of neonates. Based on a NOAEL of 333 microg MCLR/kg bw/day, a safety factor of 1000, consumption of 2 g/day of A. flos-aquae by a 60-kg adult, the safe level of MCLR as a contaminant of A. flos-aquae products is calculated to be 10.0 microg MCLR/g.

PMID: 10499991
From PubMed

Detection of cyanobacterial toxins (microcystins) in waters of northeastern Wisconsin by a new immunoassay technique.

McDermott CM, Feola R, Plude J.

Department of Biology and Microbiology, University of Wisconsin, Oshkosh 54901, USA.

The development of reliable, sensitive immunoassay techniques for detection of microcystins in water is becoming increasingly important. We have developed an enzyme-linked immunosorbent assay (ELISA) potentially able to detect microcystins at concentrations as low as 95 pg microcystin/ml water. The procedure uses antibodies extracted from the eggs of immunized chickens, eliminating the need to collect blood from laboratory rabbits. The antibody is able to recognize microcystin-LR, and -RR, and may recognize other forms of microcystin. The newly developed ELISA technique was utilized to measure the amount of microcystin in waters of northeastern Wisconsin. Of the water samples analyzed, 87% contained measurable amounts of microcystin (0.2-200 ng/ml). Organisms of the genus Microcystis were identified most frequently from microcystin-containing waters. The distribution of microcystin-producing cyanobacterial strains was apparently random throughout the sampling area.

PMID: 8744983
From PubMed

Silent but widespread use of dietary supplements.

Naylor S, Gleich GJ.

Comment on:

• Mayo Clin Proc. 1999 May;74(5):443-7

Publication Types:

• Comment
• Letter

PMID: 10473369
From PubMed

Release of heptapeptide toxin (microcystin) during the decomposition process of Microcystis aeruginosa.

Watanabe MF, Tsuji K, Watanabe Y, Harada K, Suzuki M.

Tokyo Metropolitan Research Laboratory of Public Health, Japan.

The decomposition process of toxic blue-green alga (cyanobacteria), Microcystis aeruginosa, under dark and aerobic condition was investigated in relation to the change of the amounts of heptapeptide toxins (microcystins YR and LR) by two experiments: one with Microcystis cells and the other with two purified microcystins. In the experiment with Microcystis cells, an increase of heterotrophic bacteria observed from the beginning of the experiment, was followed by decomposition of the algal cells and the subsequent release of microcystins into the filtrate fraction. The amounts of the toxins initially present in the cells were quantitatively detected in the filtrate fraction on the 35th day. The decomposition of microcystin YR began on the 42nd day. The decomposition rate of the two toxins was different. The decomposition rate of purified microcystins YR and LR, compared in distilled water and culture medium, respectively, indicated clearly that microcystin YR was more labile to decomposition than microcystin LR in the culture medium. At the end of the experiment (45th day) microcystin YR decreased to 58.6%, while 86.2% of microcystin LR remained.

PMID: 1344901
From PubMed

Survey of microcystins in water between 1995 and 1996 in Parana, Brazil using ELISA.

Hirooka EY, Pinotti MH, Tsutsumi T, Yoshida F, Ueno Y.

Department of Food and Drug Technology, Center of Agricultural Sciences, State University of Londrina, Parana, Brazil. hirooka@npd.uel.br

An enzyme-linked immunosorbent assay (ELISA) based on a monoclonal antibody was used to determine microcystin (MC) concentrations in water supplies and water plant samples collected between November 1995 and October 1996, from five regions of Parana, Brazil. In addition, the presence of Microcystis sp. was monitored. Of the 50 samples obtained, 12 were from an urban lake, 8 from human water supplies, 10 from recreational lakes, 13 from farm waters used for animal pasture and 7 from aquaculture facilities. M. aeruginosa was positive in all locations. MCs were positive (>50 pg ml(-1)) in 9 samples (2 samples from human water supplies, 5 from recreational lakes and 2 from animal pasture). Heavy contamination with MCs was observed in water samples collected in May 1996 from 2 recreation (swimming-fishing sites at Itaipu dam, 6380 and 10,000 pg ml(-1)) and human supplies (6627 pg ml(-1)) samples. At these sites, a large bloom of Microcystis sp. was detected. Treatment with 1 ppm Cl- reduced MCs levels, although 267 pg ml(-1) remained in the water plant samples. Our data showed frequent occurrence of Microcystis sp., which may be a hazard to humans and animals in the state of Parana. More detailed investigations are required to evaluate the risk of natural MC contamination in the water supplied in this region.

PMID: 10647512
From PubMed

Isolation and preparative purification of microcystin variants.

Ramanan S, Tang J, Velayudhan A.

Department of Bioresource Engineering, Oregon State University, Corvallis 97331-3906, USA.

Preparative reversed-phase liquid chromatography was successfully used to purify two microcystins (microcystin LR and microcystin LA) from a cyanobacterial process waste. The separation protocol involved extraction of lyophilized cells by methanol, isolation and concentration by solid-phase extraction, and purification by reversed-phase HPLC. Milligram-level loading of microcystins was obtained on a solid-phase extraction cartridge packed with 0.5 g of C18 stationary phase. The separations were first carried out on an analytical column and then scaled-up to a preparative column. The microcystins were quantified by HPLC and enzyme-linked immunosorbent assay. A method to remove microcystins rapidly and economically from the cyanobacterial process waste is also described.

PMID: 10910204
From PubMed

Use of protein phosphatase inhibition assay to detect microcystins in Donghu Lake and a fish pond in China.

Xu LH, Lam PK, Chen JP, Xu JM, Wong BS, Zhang YY, Wu RS, Harada KI.

Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan, People's Republic of China.

Seasonal variations in the level of total microcystins in water samples collected from Donghu Lake and a fish pond in Wuhan, China, were studied between March 1995 and February 1996 using a protein phosphatase inhibition assay involving a radioactive 32P-labelled substrate. The assay is highly reliable and repeatable, and is probably the most sensitive assay for microcystin detection to date. Results of the survey indicated the presence of microcystins in the water samples, and the concentration of microcystins appeared to be related to the degree of eutrophication and water temperature. There is also a correlative relationship between the quantity of microcystins and the abundance of microcystin-producing cyanobacteria (Anabaena and Oscillatoria) in the water bodies over a year cycle. In the present study, the positive detection of microcystins in water bodies having no signs of algal bloom warns of considerable potential threat of these waters to public health.

PMID: 10819179
From PubMed

[Detection of microcystins in source and tap water from a lake].

Dong C, Yu S, Chen G, Chen C.

[Article in Chinese]

Department of Epidemiology, Shanghai Medical University, China.

The microcystins in source and tap water collected from seven waterworks around a lake in summer, 1996 were detected by enzyme-linked immunosorbent assay (ELISA). Microcystins were determined in the source water from all the seven waterworks, and the concentrations ranged from 280 to 35,300 ng/L. Low concentrations of microcystins were also detected in the tap water of three waterworks. The results suggest that microcystins in source water could not be removed completely by conventional adding bleaching powder treatment.

PMID: 10682616
From PubMed

Use of a colorimetric protein phosphatase inhibition assay and enzyme linked immunosorbent assay for the study of microcystins and nodularins.

An J, Carmichael WW.

Department of Biological Sciences, Wright State University, Dayton, OH 45435.

Microcystins and nodularins are cyclic peptide hepatotoxins and tumor promoters produced by several genera of cyanobacteria. Using a rabbit anti-microcystin-LR polyclonal antibody preparation, the cross-reactivity with 18 microcystin and nodularin variants was tested. A hydrophobic amino acid, 3-amino-9-methoxy-10-phenyl-2,6,8-trimethyl-deca-4(E),6(E)-dienoic acid (Adda), which has the (E) form at the C-6 double bond in both microcystin and nodularin, was found essential for these toxins to express antibody specificity. Modification of -COOH in glutamic acid of microcystin and nodularin did not alter their antigenicity. Antibody cross-reactivity of these toxins was compared with their ability to inhibit protein phosphatase type 1 (PP1). Detection of PP1 inhibition was done by measuring the inhibition effect of the toxins on p-nitrophenol phosphate activity toward PP1. PP1 was obtained as recombinant PP1 expressed in E. coli. The inhibition effect of five microcystins and two nodularins on recombinant PP1 activity toward p-nitrophenol phospate was measured in a microwell plate reader. The concentration of microcystin-LR causing 50% inhibition of recombinant PP1 activity (IC50) was about 0.3 nM, while that of two modified microcystins had a significantly higher IC50. Microcystin-LR and nodularin with the (z) form of Adda at the C-6 double bond or having the monoester of glutamic acid did not inhibit PP1. These three toxins were also nontoxic in the mouse bioassay. These results show the importance of Adda and glutamic acid in toxicity of these cyclic peptides and that PP1 inhibition is related to the toxins' mechanism of action.

PMID: 7725318
From PubMed

[The occurrence, distribution and toxicity of cyanobacteria in the estuary of Lagoa dos Patos, Rio Grande do Sul].

Matthiensen A, Yunes JS, Codd GA.

[Article in Portuguese]

Departamento de Quimica, FURG, C.P. 474, Rio Grande, RS.

Several blooms of Microcystis aeruginosa have been observed in the Patos Lagoon estuary during the last fifteen years without a proper investigation of their ecological importance or possible toxicity. The present study has identified and quantified the presence of cyanobacteria in the Patos Lagoon estuary, particularly of M. aeruginosa. During this survey, identification and quantification of the main phytoplankton groups were done in relation to geographical distribution in the estuary. The presence of M. aeruginosa colonies in the estuarine region confirmed their superficial distribution throughout the estuarine waters during twelve months with a maximum of 1, 3.10(6) cells. L-1 in December, 1994 and a minimum of 1, 5.10(5) cells. L-1 in August, 1995 and also confirmed that M. aeruginosa originated from waters in the north of the estuary. The period of the highest cell and colonies densities was coincident with high chlorophyll-a levels in surface waters. Toxicity of M. aeruginosa bloom material was determined by bioassay and concentrations of hepatotoxins microcystins were identified by HPLC-DAD. M. aeruginosa blooms were considered highly toxic, presenting a 24 h-LD50 lower than 100 mg.Kg-1 b.w. and a toxin content higher than 1 microgram.mg-1 d.w. Several microcystin variants were found in the extracts with microcystin-LR predominating.

PMID: 10765462
From PubMed

Role of microcystins in poisoning and food ingestion inhibition of Daphnia galeata caused by the cyanobacterium Microcystis aeruginosa.

Rohrlack T, Dittmann E, Henning M, Borner T, Kohl JG.

Research Group Ecology, Department of Biology, Humboldt University, D-10099 Berlin, Germany. ThRohrlack@compuserve.com

The effects of microcystins on Daphnia galeata, a typical filter-feeding grazer in eutrophic lakes, were investigated. To do this, the microcystin-producing wild-type strain Microcystis aeruginosa PCC7806 was compared with a mcy- PCC7806 mutant, which could not synthesize any variant of microcystin due to mutation of a microcystin synthetase gene. The wild-type strain was found to be poisonous to D. galeata, whereas the mcy- mutant did not have any lethal effect on the animals. Both variants of PCC7806 were able to reduce the Daphnia ingestion rate. Our results suggest that microcystins are the most likely cause of the daphnid poisoning observed when wild-type strain PCC7806 is fed to the animals, but these toxins are not responsible for inhibition of the ingestion process.

PMID: 9925609
From PubMed

The toxicology of microcystins.

Dawson RM.

Defence Science and Technology Organisation, Aeronautical and Maritime Research Laboratory, Melbourne VIC, Australia.

Microcystins are a family of more than 50 structurally similar hepatotoxins produced by species of freshwater cyanobacteria, primarily Microcystis aeruginosa. They are monocyclic heptapeptides, characterised by some invariant amino acids, including one of unusual structure which is essential for expression of toxicity. Microcystins are chemically stable, but suffer biodegradation in reservoir waters. The most common member of the family, microcystin-LR (L and R identifying the 2 variable amino acids, in this case leucine and arginine respectively) has an LD50 in mice and rats of 36-122 microg/kg by various routes, including aerosol inhalation. Although human illnesses attributed to microcystins include gastroenteritis and allergic/irritation reactions, the primary target of the toxin is the liver, where disruption of the cytoskeleton, consequent on inhibition of protein phosphatases 1 and 2A, causes massive hepatic haemorrhage. Microcystins are tight-binding inhibitors of these protein phosphatases, with inhibition constants in the nanomolar range or lower. Uptake of microcystins into the liver occurs via a carrier-mediated transport system, and several inhibitors of uptake can antagonise the toxic effects of microcystins. The most effective of these is the antibiotic rifampin (a drug approved for clinical use), which protects mice and rats against microcystin-induced lethality when given prophylactically and, in some cases, therapeutically.

Publication Types:

• Journal Article
• Review
• Review, Tutorial

PMID: 9690788
From PubMed

Immuno-crossreactivity and toxicity assessment of conjugation products of the cyanobacterial toxin, microcystin-LR.

Metcalf JS, Beattie KA, Pflugmacher S, Codd GA.

Department of Biological Sciences, University of Dundee, Dundee DD1 4HN, UK.

Immunoassays are increasingly used to investigate the production, properties and fates of the cyanobacterial hepatotoxic microcystins in vitro and in vivo. Responses of an ELISA immunoassay to microcystins have been determined using the authentic toxin antigen, microcystin-LR, and conjugation products between the toxin and glutathione, cysteine-glycine and cysteine. The antibodies against microcystin-LR crossreacted with the toxin conjugation products with similar affinities (96-112%) to that of microcystin-LR, when assayed at a concentration of 1 microg l(-1). Toxicity assessment of the conjugates, in comparison to microcystin-LR, indicated a reduction according to mouse bioassay. In vitro protein phosphatase inhibition assay indicated that the conjugates possessed approximately 3-9-fold lower toxicity than microcystin-LR.

PMID: 10930730
From PubMed

Biliary excretion of biochemically active cyanobacteria (blue-green algae) hepatotoxins in fish.

Sahin A, Tencalla FG, Dietrich DR, Naegeli H.

Institute of Pharmacology and Toxicology, University of Zurich-Tierspital, Switzerland.

Previous reports demonstrated that microcystin and related cyanobacteria polypeptides are rapidly cleared from plasma and accumulate in liver tissue. In the present study, we have used their ability to inhibit protein phosphatases to show that these cyanobacteria hepatotoxins are excreted into the bile of experimentally poisoned rainbow trout. At various times after oral administration of hepatotoxic Microcystis aeruginosa, bile samples were analysed for microcystin content by methanol extraction and protein phosphatase assays. An inhibitory principle that specifically suppressed protein phosphatase activity was detected in all bile samples removed between 1 and 72 h after oral exposure to toxic algae. These results indicate that biochemically active microcystin molecules are excreted into the biliary tract of poisoned fish.

PMID: 8571383
From PubMed

Hazardous freshwater cyanobacteria (blue-green algae).

Elder GH, Hunter PR, Codd GA.

Department of Medical Biochemistry, University of Wales College of Medicine, Cardiff, UK.

PMID: 8099388
From PubMed

Immunoaffinity column as clean-up tool for determination of trace amounts of microcystins in tap water.

Tsutsumi T, Nagata S, Hasegawa A, Ueno Y.

Research Institute for Biosciences and Department of Toxicology and Microbial Chemistry, Faculty of Pharmaceutical Sciences, Science University of Tokyo, Ichigaya, Japan. tutumi@nihs.go.jp

Trace amounts of microcystins (MCs) in drinking water should be monitored because of their potential hazard for human health as an environmental tumor promoter. We describe here a new clean-up tool with immunoaffinity column (IAC) for determination of trace amounts of MCs (from pg to microg/litre) in tap water. The water samples were concentrated with IAC clean-up and MCs levels were determined by HPLC with UV detection or enzyme-linked immunosorbent assay (ELISA). In the combination with HPLC analysis, mean recovery of microcystin-LR (MCLR),-RR and-YR spiked to tap water were 91.8%, 77.3% and 86.4%, respectively, in the range 2.5-100 microg/litre. The chromatogram of MCs-spiked tap water sample cleaned up with IAC showed effective elimination of the impurities compared to that with octadecyl silanized cartridge, which had been cleaned up with a conventional method. Also, in the combination with highly sensitive ELISA, mean recovery of MCLR spiked to tap water was 80% in the range 0.1-1000 ng/litre. The combined methods developed here can detect pg to microg/litre of MCs in tap water. The overall results indicated that IAC will be suitable as a clean-up tool for trace amounts of MCs in tap water.

PMID: 10942320
From PubMed

Dynamics of microcystins in the mussel Mytilus galloprovincialis.

Amorim A, Vasconcelos V.

Departamento de Zoologia e Antropologia, Faculdade de Ciencias, Praca Gomes Teixeira, Porto, Portugal.

The accumulation and depuration of hepatotoxins produced by the freshwater cyanobacterium Microcystis aeruginosa in the mussel Mytilus galloprovincialis was studied. Mussels were fed daily 10(5) cells/ml of the toxic cyanobacterium that produces microcystin-LR (MCYST-LR), for four days. After that period animals were placed in toxin free water and were fed the diatom Nitzschia sp. During two weeks the concentration of the toxin in the mussels, as also in their feces and in the water where animals were placed individually during 24 h, were monitored using an ELISA assay. No mussel mortality was registered during the whole experiment. Mussels showed a maximum detectable level of MCYST of 10.7 microg/g mussels dry weight (DW) during the accumulation period, rising to 16.0 microg MCYST/g mussel DW by day two of the depuration period. Then there was a decrease trend with peaks of toxin at days 6, 8, 11 and 14. The rise of the toxin level on day two of the depuration period seems to have been due to the reingestion of contaminated feces. In fact, feces showed high amounts of MCYST during the first days of depuration with a maximum of 140 microg/d DW on day 3. This coincided with a 50% decrease on the detectable toxin in the mussels reflecting the emptiness of their digestive tract. In the water the highest level of the toxin was 2.5 microg MCYST/liter and some toxin peaks were also observed during the depuration period. This fluctuation of the toxin levels in the mussels, feces and water may be related to the renewal of protein phosphatases and subsequent release of unbound toxins. Results show that depuration of MCYST by mussels is not a very rapid process and contamination by feces containing MCYST is likely to occur and increase the persistence of these toxins in the mussels after the bloom disappearance. Monitoring programs for harmful algal blooms usually include only toxic dinoflagellates and diatoms and their toxins in bivalves. Taken into account the present work they should also include hepatotoxins from cyanobacteria, namely in brackish waters such as estuaries of eutrophic rivers in order to avoid human health hazard.

PMID: 10484739
From PubMed

Microcystin toxicosis in cattle due to overgrowth of blue-green algae.

Frazier K, Colvin B, Styer E, Hullinger G, Garcia R.

Veterinary Diagnostic and Investigational Laboratory, College of Veterinary Medicine, University of Georgia, Tifton 37193, USA.

Toxicosis due to microcystin-containing blue-green algae has been sporadically reported in a variety of animal species. Most reports of intoxication involve algal blooms during periods of warm temperatures and abundant sunshine in the spring or early summer. A case of blue-green algae toxicosis with lesions attributable to toxins from Microcystis aeruginosa is described in 4 cattle from southern Georgia during November. The case was unusual in that characteristic hepatic necrosis was accompanied by severe mesenteric edema and peritoneal effusion. In addition, weather conditions and location were not expected to be conducive to algal blooms. Rapid diagnosis and identification of the probable source of intoxication allowed the owner to move the herd away from the affected pond. This action limited losses to only the 4 cattle.

PMID: 9467204
From PubMed

Detection of cyanobacterial toxins (microcystins) in cell extracts by micellar electrokinetic chromatography.

Bouaicha N, Rivasseau C, Hennion MC, Sandra P.

CEMATMA, Laboratoire de Chimie Analytique, ESPCI, Paris, France.

A micellar electrokinetic chromatography (MEKC) method with UV detection is described for the rapid and efficient separation of three microcystins: microcystin-YR (MCYST-YR), microcystin-LR (MCYST-LR) and microcystin-RR (MCYST-RR). A detection limit of 7.5 pg for each toxin was achieved. The UV intensities of these toxins measured at 200 nm showed good linearity in the range 7.5-150 pg. The production of MCYST-LR in three cultured strains of cyanobacteria, namely Microcystis aeruginosa strain IP7806, Microcystis aeruginosa strain IP7813 and Oscillatoria agardhii strain IP7805, was evaluated.

PMID: 8930753
From PubMed

Structural modifications imparting reduced toxicity in microcystins from Microcystis spp.

Stotts RR, Namikoshi M, Haschek WM, Rinehart KL, Carmichael WW, Dahlem AM, Beasley VR.

A cyanobacterial (blue-green algal) bloom containing Microcystis aeruginosa (dominant), M. viridis, and M. wesenbergii, was collected from Homer Lake (Illinois, U.S.A.) in the summer of 1988 and microcystins were isolated. One microcystin of substantially reduced toxicity was isolated, together with ten hepatotoxic microcystins. The compound with reduced toxicity was nonlethal at 1 mg/kg (i.p. mouse) and was determined to have a (C3H7O2) mono-ester of the alpha-carboxyl on the Glu unit of microcystin-LR. The other nine microcystins apart from MCLR had approximate LD50S ranging from 97 micrograms/kg to 750 micrograms/kg.

PMID: 8342176
From PubMed

Isolation and detection of microcystins and nodularins, cyanobacterial peptide hepatotoxins.

Meriluoto J, Lawton L, Harada K.

Department of Biochemistry and Pharmacy, Abo Akademi University, Turku, Finland.

PMID: 10820716
From PubMed

Photocatalytic degradation of cyanobacterial microcystin toxins in water.

Shephard GS, Stockenstrom S, De Villiers D, Engelbrecht WJ, Sydenham EW, Wessels GF.

Programme on Mycotoxins and Experimental Carcinogenesis, Medical Research Council, Tygerberg, South Africa.

The microcystins are hepatotoxins produced by a number of cyanobacterial species (blue green algae) in fresh water systems. The increasing eutrophication of natural waters has led to an increase in the incidence of algal blooms and the consequent increased risk of microcystin contamination of water resources. The removal of microcystins LR, YR and YA from contaminated water was investigated using an experimental laboratory-scale photocatalytic 'falling film' reactor in which an oxygen purge, UV radiation and semiconductor titanium dioxide (TiO2) catalyst were used to oxidatively decompose the microcystin pollutants. Preliminary studies, using algal extracts spiked into distilled water, indicated that the microcystins were rapidly decomposed in this reactor. The decomposition followed first order reaction kinetics with half-lives of less than 5 min with the reactor operating in a closed-loop mode. Reaction rates were strongly dependent on the amount of TiO2 catalyst (O-5 g/l), but only marginally influenced by a change in gas purge from oxygen to compressed air. The use of lake water, rather than distilled water, showed that this process is feasible in natural waters, although increased levels of catalyst (up to 5 g/l) were required to achieve comparable decomposition rates.

PMID: 9839673
From PubMed

First report of microcystins in Taiwan.

Lee TH, Chen YM, Chou HN.

Department of Zoology, National Taiwan University, Taipei, ROC.

This is the first report on microcystins from Microcystis aeruginosa Kutzing in Taiwan. A total of nine strains of cyanobacteria have been isolated from eutrophic aquaculture ponds and water reservoirs. By mouse toxicity assay, six of the nine strains had LD100 in the range of 25-100 mg per kg mouse for dried bacterial mass. Microcystin-LR and -RR were found in all toxic strains and their contents ranged from 0.11-10.06 microg and 0.08 2.21 microg per mg of dried bacteria, respectively. Microcystin-RA, a minor component found only in M. TN-2 and M. CY-1 strains, was identified as a new microcystin. All three toxins were isolated by a serial separation on an LH-20 column, Si-flash column chromatography and reverse phase HPLC. Toxins were further identified by comparing their FABMS, 1H and 1H-1H COSY NMR spectra with the authentic microcystin-LR. Several other microcystin-like compounds were also found in the cultured strains and their structures are being determined.

PMID: 9620573
From PubMed

Should nature be standardized?

Grant KL, Benda W.

Publication Types:

• Editorial

PMID: 10554909
From PubMed

Hepatotoxin (microcystin) and neurotoxin (anatoxin-a) contained in natural blooms and strains of cyanobacteria from Japanese freshwaters.

Park HD, Watanabe MF, Harda K, Nagai H, Suzuki M, Watanabe M, Hayashi H.

Department of Hygiene, School of Medicine, Shinshu University, Matsumoto, Japan.

Amounts of hepatotoxic microcystin and neurotoxic anatoxin-a were estimated in natural blooms and strains of cyanobacteria from freshwaters in Japan. A simultaneous analysis method of anatoxin-a and microcystin was applied to natural bloom samples, which has been dominated by several species and the strains of cyanobacteria which produced simultaneously both toxins. The natural blooms examined in the present study were mainly composed of Anabaena and Oscillatoria, but most also contained Microcystis and other cyanobacteria. Only one sample was almost unialgal, Anabaena spiroides, collected from Lake Sagami. The toxins in 14 samples collected from nine different natural blooms during 1988-1992 were identified as microcystins-RR, -YR, and -LR; desmethyl-7-microcystin-LR (7-DMLR); and anatoxin-a. Microcystins were the main toxins contained in these natural blooms, with anatoxin-a not being detected or of very little quantity. 7-DMLR was detected in samples only from Lake Kasumigaura. Five strains of Anabaena isolated from waters in Japan produced a small amount of anatoxin-a, but no microcystins. One half of the strains of Microcystis produced microcystins and/or anatoxin-a. This is the first study showing Microcystis producing both anatoxin-a and microcystins.

PMID: 8167957
From PubMed

Simple and efficient method for isolation and measurement of cyanobacterial hepatotoxins by plant tests (Sinapis alba L.).

Kos P, Gorzo G, Suranyi G, Borbely G.

Institute of Plant Biology, Biological Research Center, Szeged, Hungary.

A simple and cost-effective method for isolating and assaying microcystins, cyanobacterial toxins, by C-18 cartridges, DEAE-cellulose (DE-52) chromatography, and a mustard (Sinapis alba L.) plant seedling test is described. The procedure results in a purity of up to 95-97% microcystin without the need for an HPLC system and justifies the use of the S. alba L. seedling test in the quantitative assessment of the toxin with an IC50 of 3 micrograms ml-1 instead of the mouse intraperitoneal test.

PMID: 7778786
From PubMed

Microwave oven and boiling waterbath extraction of hepatotoxins from cyanobacterial cells.

Metcalf JS, Codd GA.

Department of Biological Sciences, University of Dundee, Dundee, UK.

Low-cost, straightforward methods for the extraction of microcystins and nodularins from cyanobacterial cells were developed using a microwave oven and boiling waterbath. The use of organic solvents, such as methanol, which can interfere with sensitive analytical procedures, e.g. immunoassays, can thus be avoided. Analysis by protein phosphatase inhibition assay and high performance liquid chromatography indicated that purified microcystin-LR was unaffected by the microwave oven and boiling waterbath treatments. Four microcystins of differing hydrophobicities were successfully extracted from Microcystis PCC 7813 by both treatments at yields equivalent to those obtained by longer protocols using methanol. Assessment of the microwave oven and boiling waterbath extraction methods with laboratory strains and environmental samples of cyanobacteria showed good correlation with results from lyophilisation and methanol extraction, when extracts were analysed by high performance liquid chromatography with diode array detection (R(2)>/=0.92). The microwave and boiling waterbath extraction methods also sterilised the environmental bloom samples, as evidenced by the abolition of heterotrophic bacterial growth.

PMID: 10713428
From PubMed

Generation of antibodies directed against the low-immunogenic peptide-toxins microcystin-LR/RR and nodularin.

Baier W, Loleit M, Fischer B, Jung G, Neumann U, Weiss M, Weckesser J, Hoffmann P, Bessler WG, Mittenbuhler K.

Institut fur Immunbiologie der Universitat, Stefan-Meier-Str. 8, D-79104, Freiburg, Germany.

The preparation of antibodies against the liver toxin microcystin, as described here, is of major importance for its detection and purification in food and water, and for a therapeutic approach to neutralize the toxin by passive immunization. Microcystin-LR (MLR) and microcystin-RR (MRR) were purified from cyanobacterial cell materials by extraction, Sephadex LH-20-, ODS silica gel-, ionic exchange and RP-HPLC-chromatography. In order to reduce the toxicity for parenteral administration, microcystins were coupled by the carbodiimide method to poly-L-lysine (PLL(50.000)). Mice and rabbits were immunized with the conjugates in the presence of two lipopeptide immunoadjuvants (P(3)CSK(4) and P(3)CS-T(h)). High MLR-specific antibody levels were observed after parenteral coadministration of antigen and lipopeptides, whereas no anti-MLR antibodies were obtained with free microcystin or the microcystin-PLL(50.000)-conjugate in the absence of lipopeptide. In oral immunization, coadministration of antigen and adjuvants resulted in an accelerated development of anti MLR-specific antibodies and high antibody levels. Using the antisera, we could detect different microcystins and nodularin down to a concentration range of 10-50 ng/ml by a competitive inhibition ELISA; detection of microcystins in crude cell preparations was also possible. Furthermore, microcystins from different sources could be detected and discriminated from cyclic cyanopeptolines.

PMID: 10708882
From PubMed

Plant toxins.

Betz JM.

U.S. Food and Drug Administration, Division of Natural Products, Washington, DC 20204, USA.

Publication Types:

• Journal Article
• Review
• Review, Tutorial

PMID: 10367396
From PubMed

Insertional mutagenesis of a peptide synthetase gene that is responsible for hepatotoxin production in the cyanobacterium Microcystis aeruginosa PCC 7806.

Dittmann E, Neilan BA, Erhard M, von Dohren H, Borner T.

Institute for Biology (Genetics), Humboldt University, Berlin, Germany.

Several bloom-forming cyanobacterial genera produce potent inhibitors of eukaryotic protein phosphatases called microcystins. Microcystins are hepatotoxic cyclic heptapeptides and are presumed to be synthesized non-ribosomally by peptide synthetases. We identified putative peptide synthetase genes in the microcystin-producing strain Microcystis aeruginosa PCC 7806. Non-hepatotoxic strains of M. aeruginosa lack these genes. Strain PCC 7806 was transformed to chloramphenicol resistance. The antibiotic resistance cassette insertionally inactivated a peptide synthetase gene of strain PCC 7806 as revealed by Southern hybridization and DNA amplification. This is the first report of genetic transformation and mutation, by homologous recombination, of a bloom-forming cyanobacterium. Chemical and enzymatic analyses, including high-performance liquid chromatography (HPLC), mass spectrometry, amino acid activation, and protein phosphatase inhibition, revealed the inability of derived mutant cells to produce any variant of microcystin while maintaining their ability to synthesize other small peptides. The disrupted gene therefore encodes a peptide synthetase (microcystin synthetase) that is specifically involved in the biosynthesis of microcystins. Our results confirm that microcystins are synthesized non-ribosomally and that a basic difference between toxic and non-toxic strains of M. aeruginosa is the presence of one or more genes coding for microcystin synthetases.

PMID: 9427407
From PubMed

Cytotoxicity of cyanobacterium Microcystis aeruginosa.

Henning K, Cremer J, Meyer H.

Institute of Microbiology, Federal Armed Forces, Medical Academy, Munich.

Cytotoxic effects of crude extracts and fractions of the purification steps towards Microcystin-LR (MCYST-LR) were investigated in vitro. Cytotoxicity was evaluated by measure of lactate dehydrogenase liberation of Chang liver cells and by hemolysis. Crude extracts of strain PCC 7806 damaged the cells within a few minutes. In contrast, MCYST-LR did not show any detectable cytotoxic effects. The cytotoxic activity could be related to a heat-labile substance with a molecular weight of about 30,000 Da.

PMID: 1519410
From PubMed

Microcystin-LR toxicodynamics, induced pathology, and immunohistochemical localization in livers of blue-green algae exposed rainbow trout (oncorhynchus mykiss).

Fischer WJ, Hitzfeld BC, Tencalla F, Eriksson JE, Mikhailov A, Dietrich DR.

Environmental Toxicology, University of Konstanz, Germany.

With this retrospective study, we investigated the temporal pattern of toxin exposure and pathology, as well as the topical relationship between hepatotoxic injury and localization of microcystin-LR, a potent hepatotoxin, tumor promoter, and inhibitor of protein phosphatases-1 and -2A (PP), in livers of MC-gavaged rainbow trout (Oncorhynchus mykiss) yearlings, using an immunohistochemical detection method and MC-specific antibodies. H&E stains of liver sections were used to determine pathological changes. Nuclear morphology of hepatocytes and ISEL analysis were employed as endpoints to detect the advent of apoptotic cell death in hepatocytes. Trout had been gavaged with lyophilized cyanobacteria (Microcystis aeruginosa, strain PCC 7806) at acutely toxic doses of 5700 microg microcystin (MC) per kg of body weight (bw), as described previously (Tencalla and Dietrich, 1997). Briefly, 3 control and 3 test animal were killed 1, 3, 12, 24, 48, and 72 h after bolus dosing, and livers were fixed and paraffin embedded for histological analysis and later retrospective histochemical analyses. The results of the immunohistochemistry reported here revealed a time dependent, discernible increase in MC-positive staining intensity throughout the liver, clearly not concurring with the kinetics of hepatic PP inhibition observed in the same fish and reported in an earlier publication by Tencalla and Dietrich (1997). After 3 h, marked and increasing MC-immunopositivity was observed in the cytoplasm, as well as the nuclei of hepatocytes. Apoptotic cell death could be detected after 48 h, at the very earliest. These data suggest that accumulation of MC and subsequent changes in cellular morphology, PP inhibition, and hepatocyte necrosis represent the primary events in microcystin induced hepatotoxicity and appear to be associated with the reversible interaction of MC with the PP. In contrast, apoptotic cell death, as demonstrated here, seems to be of only secondary nature and presumably results from the covalent interaction of MC with cellular and nuclear PP as well as other thiol containing cellular proteins.

PMID: 10774818
From PubMed

Hepatic necrosis in sheep associated with ingestion of blue-green algae.

Done SH, Bain M.

Central Veterinary Laboratory, New Haw, Addlestone, Surrey.

PMID: 8116173
From PubMed

Immuno-gold localization of hepatotoxins in cyanobacterial cells.

Shi L, Carmichael WW, Miller I.

Department of Biological Sciences, Wright State University, Dayton, OH 45435.

A polyclonal antibody against the potent hepatotoxic cyclic peptide microcystins and nodularins was used in conjunction with immuno-gold labelling to localize the toxins in three strains of cyanobacteria. Ultrastructurally, there were no major differences between unicellular Microcystis aeruginosa strain PCC 7820 (toxin-producing strain) and M. aeruginosa strain UTEX 2063 (non-toxin-producing strain), except that M. aeruginosa PCC 7820 cells had a sheath. The thickness of the sheath was about 12 nm and was distinguishable from the cell wall at the ultrastructural level only when the specimen was stained en bloc with uranyl acetate. Microcystins and nodularin were found in M. aeruginosa PCC 7820 and Nodularia spumigena strain L-575 respectively, but not in nontoxic M. aeroginosa UTEX 2063. In M. aeruginosa PCC 7820 cells, microcystin was found primarily in the thylakoid area and nucleoid, with smaller amounts in the cell wall and sheath. Only nonspecific labelling was found in other cellular inclusions, such as polyhedral bodies, cyanophycin granules and membrane-limited inclusions. In strain N. spumigena L-575, nodularin was found in both vegetative cells and heterocysts with a distribution similar to that in M. aeruginosa PCC 7820.

PMID: 7710323
From PubMed

First report on the identification of microcystin in a water bloom collected in Belgium.

Wirsing B, Hoffmann L, Heinze R, Klein D, Daloze D, Braekman JC, Weckesser J.

Institut fur Biologie II, Mikrobiologie, Albert-Ludwigs-Universitat, Freiburg, Germany. b.wirsing@bba.de

A toxic cyanobacterial bloom dominated by Microcystis aeruginosa occurred in 1995 in three adjacent ponds near Liege (Belgium) where at the same time conspicuous bird deaths were observed. The toxicity assay using primary rat hepatocytes indicated a high hepatoxicity. A 4 h incubation yielded a LD50 of 0.23 mg bloom material (dry weight)/ml cell culture medium. Toxicity was due to hepatotoxins of the microcystin class, microcystin-LR and-RR being the major microcystins present as determined by RP-HPLC absorption spectra, 1H NMR, and ESMS spectra. Additionally, the bloom sample contained small amounts of microcystin-YR. The microcystin content of the dry bloom biomass was 870 micrograms/g (on the basis of the hepatotoxicity assay) and 556 micrograms/g (on the basis of the RP-HPLC peak area). A higher yield of microcystins was obtained by acetic acid extraction instead of methanol extraction, whereas different extraction temperatures (20 degrees C, 40 degrees C) had no effect on the yield.

PMID: 9741107
From PubMed

Toxicosis due to microcystin hepatotoxins in three Holstein heifers.

Fitzgerald SD, Poppenga RH.

Department of Pathology, College of Veterinary Medicine, Michigan State University, East Lansing 48824.

PMID: 8286478
From PubMed

The identification and toxicity of the microcystin in the waterbloom obtained from an eutrophied lake.

Xu JK, Liu YF, Zhu HG, Ding WX.

Department of Environment Health, Shanghai Medical University, China.

The water of "J" lake has been seriously eutrophied; concentration of total nitrogen (TN), total phosphorus (TP) and chlorophyll a were all far above the 3rd level of the National Standard of Ground Water of China. The concentration of microcystin (MCYST) of the water at one site (M) was 1865 micrograms/l. There were 2.36 micrograms MCYST-LR per mg dry waterbloom powder.

PMID: 11055011
From PubMed

Raw animal tissues and dietary supplements.

Norton SA.

Publication Types:

• Letter

PMID: 10928886
From PubMed

Monitoring of microcystin-protein phosphatase adduct formation with immunochemical methods.

Liu BH, Yu FY, Huang X, Chu FS.

Department of Food Microbiology & Toxicology, University of Wisconsin-Madison 53706, USA.

Using anti-microcystin-LR monoclonal antibodies, an immunoblotting procedure was developed to monitor the formation of microcystin-protein phosphatase adducts in vitro and in vivo. The detection limits for the covalent binding of MCYST-LR with the recombinant protein phosphatase 1 (PP1) and rabbit liver cytosol proteins were found to be 0.1 ng and 0.3 ng per assay, respectively. MCYST-PP1 adducts were detected 30 s after the addition of MCYST-LR into the reaction mixture. Reduction of the methyldehydroalanine (Mdha) residue of MCYST-LR with ethanethiol totally abolished the covalent binding of the toxin to PP1, but retained its inhibitory toxicity on PP1. Immunoblotting analyses and enzyme-linked immunosorbant assay showed that between 5 min to 16 h after i.p. injection of single dose (35 microg/kg) of MCYST-LR into mice, approximately 0-27% of the injected toxin was found covalently bound while 0.2-9.2% existed as free form in liver cytosol.

PMID: 10673155
From PubMed

Detection of microcystins, a blue-green algal hepatotoxin, in drinking water sampled in Haimen and Fusui, endemic areas of primary liver cancer in China, by highly sensitive immunoassay.

Ueno Y, Nagata S, Tsutsumi T, Hasegawa A, Watanabe MF, Park HD, Chen GC, Chen G, Yu SZ.

Faculty of Pharmaceutical Sciences, Science University of Tokyo, Japan.

An epidemiological survey for the causes of a high incidence of primary liver cancer (PLC) in Haimen city, Jian-Su province and Fusui county, Guangxi province in China, found a close correlation between the incidence of PLC and the drinking of pond and ditch water. With an aim to clarify whether microcystins (MC), a hepatotoxic peptide produced by water bloom algae, contaminate the drinking water in the endemic areas of PLC in China, a highly sensitive enzyme-linked immunosorbent assay with a detection limit of 50 pg/ml, was introduced to monitor the MC. Three trials to survey the drinking water were carried out in 1993-1994. Samples, 1135 in total, were collected from different sources such as: ponds, ditches, rivers, shallow wells and deep wells in Haimen city. The first survey in September 1993 found that three out of 14 ditch water specimens were positive for MC, with a range of 90-460 pg/ml. Several toxic algae such as Oscillatoria agardhii were present in some of the ditches. In the second trial, samples were collected from five ponds/ditches, two rivers, two shallow wells and two deep wells monthly for the whole year of 1994. These data showed that MC was highest in June to September, with a range of 62-296 pg/ml. A third trial on the 989 different water samples collected from the different types of water sources in July 1994 revealed that 17% of the pond/ditch water, 32% of the river water, and 4% of the shallow-well water were positive for MC, with averages of 101, 160 and 68 pg/ml respectively. No MC was detected in deep well water. A similar survey on 26 drinking water samples in Fusui, Guangxi province, demonstrated a high contamination frequency of MC in the water of ponds/ditches and rivers but no MC in shallow and deep wells. These data support a hypothesis that the blue-green algal toxin MC in the drinking water of ponds/ditches and rivers, or both, is one of the risk factors for the high incidence of PLC in China. Based on previous findings on the epidemiology of PLC and the present results from the mass screening of MC in the drinking water, an advisory level of MC in drinking water was proposed to below 0.01 microg/l. The combined effect of a potent hepatocarcinogen AFB1 and an intermittent intake of MC in drinking water in the summer season was discussed as an etiology of PLC.

PMID: 8681449
From PubMed

Isolation and identification of eight microcystins from thirteen Oscillatoria agardhii strains and structure of a new microcystin.

Luukkainen R, Sivonen K, Namikoshi M, Fardig M, Rinehart KL, Niemela SI.

Department of Applied Chemistry and Microbiology, University of Helsinki, Finland.

Microcystins (cyclic heptapeptide hepatotoxins), isolated from 13 freshwater Oscillatoria agardhii strains from eight different Finnish lakes by high-performance liquid chromatography, were characterized by amino acid analysis, fast atom bombardment mass spectrometry (FABMS), and tandem FABMS (FABMS/collisionary-induced dissociation/MS). All strains produced two to five different microcystins. In total, eight different compounds, of which five were known microcystins, were isolated. The known compounds identified were [D-Asp3]MCYST (microcystin)-LR, [Dha7]MCYST-LR, [D-Asp3]MCYST-RR, [Dha7]MCYST-RR, and [D-Asp3,Dha7]MCYST-RR. This is the first time that isolation of these toxins from Oscillatoria spp., with the exception of [D-Asp3]MCYST-RR, has been reported. Three of the strains produced a new microcystin, and the structure was assigned as [D-Asp3,Mser7]MCYST-RR. The structures of two new microcystins, produced as minor components by one Oscillatoria strain, could not be determined because of the small amounts isolated from the cells. Four strains produced [Dha7]MCYST-RR as the main toxin, but [D-Asp3]MCYST-RR was clearly the most abundant and most frequently occurring toxin among these isolates of O. agardhii.

PMID: 8357254
From PubMed

Possible cause of unnatural mass death of wild birds in a pond in Nishinomiya, Japan: sudden appearance of toxic cyanobacteria.

Matsunaga H, Harada KI, Senma M, Ito Y, Yasuda N, Ushida S, Kimura Y.

School of Pharmaceutical Sciences, Mukogawa Women's University, Nishinomiya, Japan.

During the summer of 1995, about 20 spot-billed ducks died unnaturally in a pond (Shin-ike) in Nishinomiya, Hyogo Prefecture, Japan. The suspected cause was the sudden appearance of toxic freshwater bloom of cyanobacteria. However, no birds died in a nearby pond (Oo-ike) in which the cyanobacteria was also present. Morphological observation of these cyanobacteria by microscope revealed that they were almost unialgal and were both Microcystis aeruginosa. The lyophilized algal cell powder from Shin-ike contained large amounts of microcystins which showed acute toxicity for mouse, while that from Oo-ike had only a very small amount of microcystin-RR which did not show acute toxicity. Autopsy of one of the birds revealed that the liver was necrotic and severely jaundiced with a dark green color, suggesting the toxicity of the microcystins. These results point to the cause of the unnatural death of spot-billed ducks in Shin-ike as being the sudden appearance of toxic Microcystis aeruginosa. This was due to eutrophication of the pond, following the influx of untreated sewage related to damage from the Great Hanshinn Earthquake of January 1995. This is the first experimental report of toxic cyanobacteria being implicated in the mass death of wild birds in Japan.

PMID: 10495470
From PubMed

Characterization of heptapeptide toxins extracted from Microcystis aeruginosa (Egyptian isolate). Comparison with some synthesized analogs.

Abdel-Rahman S, el-Ayouty YM, Kamael HA.

Chemistry Department, Faculty of Science, Zagazig University, Egypt.

Four toxic peptides from local fresh water cyanobacterium Microcystis aeruginosa were purified and identified by high performance liquid chromatography (HPLC) and ion spray mass spectroscopic studies as: RR; YR; LR and LA with molecular weights of 1006.8, 1073, 984.8 and 910.6 respectively. Amino acid analysis indicated the presence of equimolar amounts of aspartic acid, glutamic acid, arginine, leucine and tyrosine, in addition to both alanine and dehydroalanine. Mouse assay toxicity indicated that the first two peptides, at the peak area of RR, YR, were highly toxic with LD50 20, 18.2 micrograms/kg body weight; however, the latter two, at the peak areas LR and LA, have a lesser toxicity with LD50 36 and 40 micrograms/kg body weight respectively. Three linear peptide analogs to those naturally found devoid of Adda were synthesized using the continuous flow technique. HPLC pure synthesized analog products were tested for toxicity using male mice (i.p. injection). None of them induced toxic activity.

PMID: 8382198
From PubMed

[Natural poisons: (1) Algae toxins].

Ueno Y, Nagata S.

[Article in Japanese]

Publication Types:

• Journal Article
• Review
• Review, Tutorial

PMID: 7966446
From PubMed

An ultrasensitive competitive binding assay for the detection of toxins affecting protein phosphatases.

Serres MH, Fladmark KE, Doskeland SO.

Department of Anatomy and Cell Biology, University of Bergen, Norway.

An ultrasensitive assay is described for microcystin-LR and other substances (microcystins, nodularin, okadaic acid, calyculin A, tautomycin) which block the active site of protein phosphatases (PP) 1 and 2A. The assay is based on competition between the unknown sample and [125I]microcystin-YR for binding to the catalytic subunit of PP2A. The PP2A-bound [125I]microcystin-YR was stable (half-time of dissociation = 1.8 h), allowing non-bound [125I]microcystin-YR to be removed by Sephadex G-50 size-exclusion chromatography. Compared to current assays based on inhibition of protein phosphatase activity the present assay was more robust against interference (from fluoride, ATP, histone, and casein), and had an even better sensitivity. The detection limit was below 50 pM (2.5 fmol) for nodularin and microcystin-LR, and below 200 pM (10 fmol) for okadaic acid. The method was used successfully to detect extremely low concentrations of either microcystin or nodularin in drinking water or seawater, and okadaic acid in shellfish extract.

PMID: 10669024
From PubMed

The toxicity of cyanobacterial toxins in the mouse: I microcystin-LR.

Fawell JK, Mitchell RE, Everett DJ, Hill RE.

WRc National Centre for Environmental Toxicology, Medmenham, Bucks, England.

Blooms of cyanobacteria or blue-green algae are known to have caused poisoning in fish, waterfowl, animals and man. One of the toxins responsible for this is the hepatotoxin microcystin-LR which has been found to occur in blooms present intermittently in sources used for domestic water supplies. Three sets of experiments were undertaken to investigate the acute toxicity of microcystin-LR in mice and rats by the oral and intraperitoneal routes, the potential for effects on foetal development in the mouse, and the effects of repeated oral dosing over 13 weeks in the mouse. The results of this work were as follows: (1) Microcystin-LR is 30-100 times less toxic via oral ingestion than via intraperitoneal injection; (2) Microcystin-LR is not a selective developmental toxicant in the mouse. There was a No Observed Adverse Effect Level (NOAEL) of 600 microg kg(-1) bodyweight per day given on days 6-15 of pregnancy for any form of developmental toxicity; (3) There was a clear NOAEL for tissue damage in the liver of 40 microg kg(-1) bodyweight per day of microcystin-LR. Using this data, a value of 1 microg l(-1) microcystin-LR would be an appropriate guideline value for drinking water.

PMID: 10215106
From PubMed

Seven new microcystins possessing two L-glutamic acid units, isolated from Anabaena sp. strain 186.

Namikoshi M, Yuan M, Sivonen K, Carmichael WW, Rinehart KL, Rouhiainen L, Sun F, Brittain S, Otsuki A.

Department of Ocean Sciences, Tokyo University of Fisheries, Japan. namikosh@tokyo-u-fish.ac.jp

Electrospray ionization mass spectrometry has been applied to the structure assignment of seven new microcystins (1-7), obtained from cultured Anabaena sp. strain 186. The seven new microcystins contain the dehydroalanine (Dha) or L-Ser unit instead of the N-methyldehydroalanine unit and the L-Glu and/or its delta-methyl ester [E(OMe)] units at the two variable L-amino acid units, and the structures were assigned as [Dha7]microcystin-E(OMe)E(OMe) (1), [D-Asp3,Dha7]microcystin-E(OMe)E(OMe) (2), [L-Ser7]microcystin-E(OMe)E(OMe) (3), [D-Asp3,L-Ser7]microcystin-E(OMe)E(OMe) (4), [Dha7]microcystin-EE(OMe) (5), [D-Asp3,Dha7]microcystin-EE(OMe) (6), and [L-Ser7]microcystin-EE(OMe) (7). These microcystins are the first examples containing dicarboxylic amino acids at the two variable L-amino acid units in microcystins.

PMID: 9511906
From PubMed

[Effect of the toxigenic strains of cyanobacterium Microcystis aeruginosa on the larvae of the common frog].

Gromov BV, Mamkaeva KA, Filatova EV.

[Article in Russian]

PMID: 9376815
From PubMed

[Cyanobacteria, their toxins and health risks].

Thebault l, Lesne J, Boutin JP.

[Article in French]

Service de Medecine des Collectivites, l'Hopital d'Instruction des Armees Clermont-Tonnerre, Brest, France.

Cyanobacteria (blue-green algae) commonly occur in fresh and brackish water where they produce blooms under certain environmental and climatic conditions. Since some species produce neurotoxins, hepatotoxins, cytotoxins, and endotoxins, blooms can be hazardous for animal and human health. Several cases of human cyanobacterial poisoning have been documented, but accurate assessment of the risk is difficult for lack of knowledge concerning exposure levels and the incidence of this kind of poisoning. Most human cases have been reported after oral consumption of contaminated drinking water or swimming in recreation waters where blooms have occurred. Further study is needed to evaluate and manage this risk, especially in regions dependent on surface water for drinking and recreational water areas. This is especially true in tropical and intertropical areas where climatic conditions promote occurrence of cyanobacteria blooms and nothing is known of the impact on public health.

Publication Types:

• Journal Article
• Review
• Review, Tutorial

PMID: 8830224
From PubMed

Toxins and genetically modified food.

Trewavas A.

Comment on:

• Lancet. 2000 Jan 29;355(9201):414

Publication Types:

• Comment
• Letter

PMID: 10752731
From PubMed

The adsorption of microcystin-LR by natural clay particles.

Morri RJ, Williams DE, Luu HA, Holmes CF, Andersen RJ, Calvert SE.

Department of Chemistry, University of British Columbia, Vancouver, Canada.

The microcystin cyanobacterial hepatotoxins represent an increasingly severe global health hazard. Since microcystins are found world wide in drinking water reservoirs concern about the impact on human health has prompted investigations into remedial water treatment methods. This preliminary study investigates the scavenging from water of microcystin-LR by fine-grained particles known to have a high concentration of the clay minerals kaolinite and montmorillonite. The results show that more than 81% of microcystin-LR can be removed from water by clay material. Thus, microcystin-LR is indeed scavenged from water bodies by fine-grained particles and that this property may offer an effective method of stripping these toxins from drinking water supplies.

PMID: 10665811
From PubMed

Fatal microcystin intoxication in haemodialysis unit in Caruaru, Brazil.

Pouria S, de Andrade A, Barbosa J, Cavalcanti RL, Barreto VT, Ward CJ, Preiser W, Poon GK, Neild GH, Codd GA.

Institute of Urology and Nephrology, University College London Medical School, UK.

BACKGROUND: After a drought in February, 1996, all 126 patients in a haemodialysis unit in Caruaru, north-east Brazil, developed signs and symptoms of acute neurotoxicity and subacute hepatotoxicity following the use of water from a lake with massive growth of cyanobacteria (blue-green algae). 60 patients died. METHODS: Besides recording clinical details and outcome at follow-up, we arranged laboratory, radiological, and histological investigations on the patients and toxicological studies of serum and haemodialysis water filters. FINDINGS: The acute presentation was with malaise, myalgia and weakness, nausea and vomiting, and tender hepatomegaly, with a range of neurological symptoms from tinnitus, vertigo, headaches, and deafness to blindness and convulsions. Liver injury ranged from abnormal liver-function test results to rapidly progressive and fatal hepatic failure. Biochemical investigations revealed gross hyperbilirubinaemia, abnormal liver enzyme activities, and hypertriglyceridaemia, but there was no evidence of haemolysis or microangiopathy. Histology revealed a novel acute toxic hepatitis with diffuse panlobular hepatocyte necrosis, neutrophil infiltration, canalicular cholestasis, and regenerative multinucleate hepatocytes. Samples of serum, dialysis filters, and water-treatment columns contained microcystins, the highly toxic low-molecular-weight hepatotoxins produced by cyanobacteria. INTERPRETATION: Cyanobacteria present water-borne hazards to health via drinking water and recreational water. Haemodialysis presents an additional high-risk exposure route: when they enter directly into the circulation, microcystins can lead to fatal clinical syndromes ranging from acute neurotoxic illness to subacute liver failure.

PMID: 9800741
From PubMed

Enzymatic pathway for the bacterial degradation of the cyanobacterial cyclic peptide toxin microcystin LR.

Bourne DG, Jones GJ, Blakeley RL, Jones A, Negri AP, Riddles P.

Department of Biochemistry, University of Queensland, St. Lucia, Australia.

An isolated bacterium, identified as a new Sphingomonas species, was demonstrated to contain a novel enzymatic pathway which acted on microcystin LR, the most common cyanobacterial cyclic peptide toxin. Degradation of microcystin LR was mediated by at least three intracellular hydrolytic enzymes. The use of classic protease inhibitors allowed (i) the classification of these enzymes into general protease families and (ii) the in vitro accumulation of otherwise transient microcystin LR degradation products. The initial site of hydrolytic cleavage of the parent cyclic peptide by an enzyme that we designate microcystinase is at the 3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-deca-4,6-dienoic acid (Adda)-Arg peptide bond. Two intermediates of microcystin LR enzymatic degradation have been identified; one is linearized (acyclo-) microcystin LR, NH2-Adda-Glu(iso)-methyldehydroalanine-Ala-Leu-beta-methylas partate-Arg-OH, and the other is the tetrapeptide NH2-Adda-Glu(iso)-methyldehydroalanine-Ala-OH. The intermediate degradation products were less active than the parent cyclic peptide; the observed 50% inhibitory concentrations for crude chicken brain protein phosphatase were 0.6 nM for microcystin LR, 95 nM for linear LR, and 12 nM for the tetrapeptide. These linear peptides were nontoxic to mice at doses up to 250 micrograms/kg. Ring opening of the potent hepatotoxin microcystin LR by bacterial microcystinase effectively renders the compound nontoxic by dramatically reducing the interaction with the target protein phosphatase.

PMID: 8899999
From PubMed

Functional foods.

Katan MB.

Wageningen Centre for Food Sciences and Division of Human Nutrition and Epidemiology, Wageningen Agricultural University, The Netherlands.

PMID: 10485719
From PubMed

A biochemical profile for predicting the chronic exposure of sheep to Microcystis aeruginosa, an hepatotoxic species of blue-green alga.

Carbis CR, Simons JA, Mitchell GF, Anderson JW, McCauley I.

La Trobe University, Department of Botany, Victoria, Australia.

Sheep which grazed on the shoreline of a fresh-water lake which had a toxic bloom of Microcystis aeruginosa were studied for evidence of chronic poisoning, and a serum biochemical profile was developed to indicate sub-lethal, chronic poisoning in the sheep which had been exposed to microcystins. The profile included measurements of glutamate dehydrogenase (GLDH), gamma-glutamyl transferase (gamma GT), bile acids, bilirubin and albumin. Of 18 sheep which were exposed to M aeruginosa for more than three months, 100 per cent had high serum concentrations of bile acids, 94 per cent had high activities of GLDH and gamma GT, 83 per cent had high bilirubin and 72 per cent had low albumin concentrations compared with the median values of unexposed animals. Other sheep which were exposed for shorter periods, showed evidence of hepatic injury after one week of exposure. The majority of the sheep showed no preference for an alternative, uncontaminated source of water.

PMID: 7871250
From PubMed

Toxicology and risk assessment of freshwater cyanobacterial (blue-green algal) toxins in water.

Duy TN, Lam PK, Shaw GR, Connell DW.

Faculty of Environmental Sciences, Griffith University, Nathan, Queensland, Australia.

The occurrence of cyanobacterial toxins affects aquatic organisms, terrestrial animals (both wild and domestic), and humans. Detrimental effects have been documented in the scientific literature during the past 50 years. Possible guideline values of some cyanobacterial toxins (microcystins, cylindrospermopsin, and anatoxin-a) are estimated, and they show that children and infants are more susceptible to cyanobacterial toxins than adults. Therefore, particular attention should be paid when cyanobacterial blooms occur, even at relatively low cell counts, to protect children and infants from possible risks. Based on these guideline values and the occurrence of the toxins, it can be concluded that chronic and subchronic exposure to cyanobacterial toxins does occur in some populations, particularly in developing countries where high proportions of the population consume untreated surface water directly, such as pond, ditch, river, or reservoir water. Because wildlife and domestic animals consume a large amount of untreated water daily, they are at higher risk than humans from cyanobacterial toxins. Calculated guideline values in Section X show that a relatively high risk posed by the toxins to these animals is likely to occur, even at low cell densities.

Publication Types:

• Journal Article
• Review
• Review, Tutorial

PMID: 10771585
From PubMed

Cyanobacterial toxins: removal during drinking water treatment, and human risk assessment.

Hitzfeld BC, Hoger SJ, Dietrich DR.

Environmental Toxicology, University of Konstanz, Konstanz, Germany. bettina.hitzfeld@uni-konstanz.de

Cyanobacteria (blue-green algae) produce toxins that may present a hazard for drinking water safety. These toxins (microcystins, nodularins, saxitoxins, anatoxin-a, anatoxin-a(s), cylindrospermopsin) are structurally diverse and their effects range from liver damage, including liver cancer, to neurotoxicity. The occurrence of cyanobacteria and their toxins in water bodies used for the production of drinking water poses a technical challenge for water utility managers. With respect to their removal in water treatment procedures, of the more than 60 microcystin congeners, microcystin-LR (L, L-leucine; R, L-arginine) is the best studied cyanobacterial toxin, whereas information for the other toxins is largely lacking. In response to the growing concern about nonlethal acute and chronic effects of microcystins, the World Health Organization has recently set a new provisional guideline value for microcystin-LR of 1.0 microg/L drinking water. This will lead to further efforts by water suppliers to develop effective treatment procedures to remove these toxins. Of the water treatment procedures discussed in this review, chlorination, possibly micro-/ultrafiltration, but especially ozonation are the most effective in destroying cyanobacteria and in removing microcystins. However, these treatments may not be sufficient during bloom situations or when a high organic load is present, and toxin levels should therefore be monitored during the water treatment process. In order to perform an adequate human risk assessment of microcystin exposure via drinking water, the issue of water treatment byproducts will have to be addressed in the future.

Publication Types:

• Journal Article
• Review
• Review, Academic

PMID: 10698727
From PubMed

Detection of an anatoxin-a(s)-like anticholinesterase in natural blooms and cultures of cyanobacteria/blue-green algae from Danish lakes and in the stomach contents of poisoned birds.

Henriksen P, Carmichael WW, An J, Moestrup O.

Department of Phycology, University of Copenhagen, Denmark.

Ten natural bloom samples of cyanobacteria from the Danish lakes Knud so (5), Ravn so (4), and Salten Langso (1) collected during 1993-1995 were assayed for toxicity by mouse bioassay, for acetylcholinesterase inhibiting activity by a colorimetric method, and for microcystins by enzyme-linked immunosorbent assay. In the mouse bioassay, seven samples were neurotoxic, two were non-toxic and one gave a protracted toxic response. One of the non-toxic and the single protracted toxic sample both contained anticholinesterase activity equivalent to 4 micrograms anatoxin-a(s) g-1. The neurotoxic samples contained equivalents to 20-3300 micrograms anatoxin-a(s) g-1. The highest anticholinesterase activities (equivalent to 2300 and 3300 micrograms anatoxin-a(s) g-1, respectively) were found in samples collected from Lake Knud so in connection with bird-kills in 1993 and 1994. Small amounts of microcystins (0.1-0.9 microgram g-1) were detected in all samples but one. All Lake Knud so and Lake Ravn so samples were dominated by Anabaena lemmermannii, and the Lake Salten Langso sample by several species of Anabaena. Gel filtration profiles indicated similarity between the toxic component from the Lake Knud so 1994 bloom with registered bird-kills and anatoxin-a(s) isolated from Anabaena flos-aquae NRC-525-17. Anticholinesterase-producing cultures of A. lemmermannii were isolated from the Lake Knud so 1993 bloom. These laboratory cultures produced anatoxin-a(s) equivalents of 29-743 micrograms g-1. Other cultures of A. lemmermannii isolated from Lake Knud so and Lake Ravn so were hepatotoxic or non-toxic. Dead birds collected from Lake Knud so during the neurotoxic 1993 Anabaena bloom possibly died from cyanobacterial toxicosis. The stomach contents contained colonies and single trichomes of Anabaena, and anticholinesterase activities equivalent to 2.1-89.7 micrograms anatoxin-a(s) kg-1 body weight and microcystins (53-95 ng kg-1) were also detected.

PMID: 9241784
From PubMed

Microcystin uptake inhibits growth and protein phosphatase activity in mustard (Sinapis alba L.) seedlings.

Kurki-Helasmo K, Meriluoto J.

Department of Biochemistry and Pharmacy, Abo Akademi University, Turku, Finland.

Mustard (Sinapis alba L.) seeds were cultivated for seven days on a solid nutrient medium supplemented with 040 microg microcystin-RR per ml. Microcystin-RR affected seedling growth (IC50 0.8 microg/ml) and microcystin concentrations > or =5.0 microg/ml produced malformed plants. The inhibition of protein phosphatase 1 and 2A activity correlated with the growth inhibition. The seedlings were also shown to take up 3H-dihydromicrocystin-LR derived radioactivity up to a level corresponding to ca. 80 ng toxin per mg plant protein.

PMID: 9839676
From PubMed

Natural health products get own directorate at Health Canada.

Gray C.

Publication Types:

• News

PMID: 10920739
From PubMed

SAMe: a dietary remedy for mind and body?

Cerrato PL, Rowell N.

Institute of Human Nutrition, Columbia University College of Physicians and Surgeons, Westchester Medical Center, City University of New York, USA.

PMID: 10655886
From PubMed

14C-labeled microcystin-LR administered to Atlantic salmon via intraperitoneal injection provides in vivo evidence for covalent binding of microcystin-LR in salmon livers.

Williams DE, Craig M, Dawe SC, Kent ML, Andersen RJ, Holmes CF.

Department of Chemistry, University of British Columbia, Vancouver, Canada.

The tissue distribution and clearance of radiolabeled microcystin-LR administered to Atlantic salmon via i.p. injection has been re-examined using uniformly 14C-labeled toxin. Significant differences were found to exist between these results and those obtained when fish received an i.p. injection of tritium-labeled dihydromicrocystin-LR. In addition, MeOH liver extracts were assayed by both phosphatase assay and 14C counts and the results compared with the total levels of incorporation determined by digestion and subsequent 14C counting of the same live tissues. An attempt to investigate the metabolism and to document the putative products was also undertaken. It was found that microcystin-LR was extensively metabolized to compounds that are more polar than the parent compound.

PMID: 9241792
From PubMed

Variation of microcystin content of microcystis aeruginosa relative to medium N:P ratio and growth stage.

Lee SJ, Jang MH, Kim HS, Yoon BD, Oh HM.

Environmental Bioresources Laboratory, Korea Research Institute of Bioscience and Biotechnology, Taejon, Korea.

Changes in the microcystin content of Microcystis aeruginosa UTEX 2388 were investigated at several N:P ratios of the medium and various growth stages. Under the P-fixed condition, the microcystin content of the cells changed with different medium N:P ratios, with the highest at 2748 microg g-1 at a N:P ratio of 16 after incubation for 7 d. The microcystin content of M. aeruginosa exhibited a high correlation with the total N content regardless of an N-fixed or P-fixed culture. When the N:P ratio of the medium was fixed to 16 : 1, the microcystin content of M. aeruginosa at various growth stages was highest at 2191 &mgr;g g-1 after an incubation of 4 d and the chlorophyll-a content showed a similar tendency. There was a highly significant relationship between the microcystin content of M. aeruginosa and the chlorophyll-a concentration in the culture during the incubation. Accordingly, the microcystin content of M. aeruginosa during incubation can be easily estimated and monitored by measuring the in vivo fluorescence changes in the culture.

PMID: 10971766
From PubMed

Cyanobacterial toxins in Portugal: effects on aquatic animals and risk for human health.

Vasconcelos VM.

Departamento de Zoologia e Antropologia, Faculdade de Ciencias do Porto, Universidade do Porto, Portugal.

Toxic cyanobacteria are common in Portuguese freshwaters and the most common toxins are microcystins. The occurrence of microcystin-LR (MCYST-LR) has been reported since 1990 and a significant number of water reservoirs that are used for drinking water attain high levels of this toxin. Aquatic animals that live in eutrophic freshwater ecosystems may be killed by microcystins but in many cases the toxicity is sublethal and so the animals can survive long enough to accumulate the toxins and transfer them along the food chain. Among these, edible mollusks, fish and crayfish are especially important because they are harvested and sold for human consumption. Mussels that live in estuarine waters and rivers where toxic blooms occur may accumulate toxins without many significant acute toxic effects. In this study data are presented in order to understand the dynamics of the accumulation and depuration of MCYST-LR in mussels. The toxin is readily accumulated and persists in the shellfish for several days after contact. In the crayfish the toxin is accumulated mainly in the gut but is also cleared very slowly. In carps, although the levels of the toxins found in naturally caught specimens were not very high, some toxin was found in the muscle and not only in the viscera. This raises the problem of the toxin accumulation by fish and possible transfer through the food chain. The data gathered from these experiments and from naturally caught specimens are analyzed in terms of risk for human consumption. The occurrence of microcystins in tap water and the incidence of toxic cyanobacteria in fresh water beaches in Portugal are reported. The Portuguese National Monitoring Program of cyanobacteria is mentioned and its implications are discussed.

Publication Types:

• Journal Article
• Review
• Review, Tutorial

PMID: 10347780
From PubMed

Variation of microcystins, cyanobacterial hepatotoxins, in Anabaena spp. as a function of growth stimuli.

Rapala J, Sivonen K, Lyra C, Niemela SI.

Department of Applied Chemistry and Microbiology, University of Helsinki, Finland.

Cyanobacterial hepatotoxins, microcystins, are specific inhibitors of serine/threonine protein phosphatases and potent tumor promoters. They have caused several poisonings of animals and also pose a health hazard for humans through the use of water for drinking and recreation. Different strains of the same cyanobacterial species may variously be nontoxic, be neurotoxic, or produce several microcystin variants. It is poorly understood how the amount of toxins varies in a single strain. This laboratory study shows the importance of external growth stimuli in regulating the levels and relative proportions of different microcystin variants in two strains of filamentous, nitrogen-fixing Anabaena spp. The concentration of the toxins in the cells increased with phosphorus. High temperatures (25 to 30 degrees C), together with the highest levels of light studied (test range, 2 to 100 mumol m-2 s-1), decreased their amount. Different structural variants of microcystins responded differently to growth stimuli. Variants of microcystin (MCYST)-LR correlated with temperatures below 25 degrees C, and those of MCYST-RR correlated with higher temperatures. Nitrogen added into the growth medium and increasing temperatures increased the proportion of microcystin variants demethylated in amino acid 3. All variants remained mostly intracellular. Time was the most important factor causing the release of the toxins into the growth medium. Time, nitrogen added into the growth medium, and light fluxes above 25 mumol m-2 s-1 significantly increased the concentrations of the dissolved toxins. According to the results, it thus seems that the reduction of phosphorus loads in bodies of water might play a role in preventing the health hazards that toxic cyanobacterial water blooms pose, not only by decreasing the cyanobacteria but also by decreasing their toxin content.

PMID: 9172340
From PubMed

Larvicidal microcystin toxins of cyanobacteria affect midgut epithelial cells of Aedes aegypti mosquitoes.

Saario E, Abdel-Hameed A, Kiviranta J.

Department of Pathology, College of Veterinary Medicine, University of Helsinki, Finland.

PMID: 7841498
From PubMed

Microcystins (cyanobacterial toxins) in drinking water enhance the growth of aberrant crypt foci in the mouse colon.

Humpage AR, Hardy SJ, Moore EJ, Froscio SM, Falconer IR.

Department of Clinical and Experimental Pharmacology, University of Adelaide, Australia.

Microcystis aeruginosa produces toxic cyclic peptides called microcystins, potent hepatotoxins that have been implicated in tumor promotion in skin and liver. The model used in this investigation was the azoxymethane (AOM)-induced aberrant crypt focus (ACF) in the male C57Bl/6J mouse colon. Three intraperitoneal (i.p.) injections of 5 mg/kg AOM were administered at 7-d intervals to mice; 19 d after the last AOM injection, drinking water containing Microcystis extract was commenced and continued for a further 212 d. The content of microcystins in the drinking water was determined by mouse bioassay, high-performance liquid chromatography (HPLC), capillary eletrophoresis, and protein phosphatase inhibition. The doses employed were 0, 382, and 693 micrograms/kg bodyweight/d at the midpoint of the trial. Following postmortem examination blood cells, serum enzymes and organ pathology were investigated. A significant microcystin dose-dependent increase in the area of aberrant crypt foci was observed. There was no marked increase in the number of crypts/colon. Two overt colonic tumors (approximately 30 mm3) were seen in microcystin-treated mice, and one microscopic colonic tumor in an AOM-alone-treated mouse. This investigation provides the first evidence for the stimulation of preneoplastic colon tumor growth by microcystin.

PMID: 11036504
From PubMed

Preference of mice to consume Microcystis aeruginosa (toxin-producing cyanobacteria): a possible explanation for numerous fatalities of livestock and wildlife.

Lopez Rodas V, Costas E.

Genetica, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid, 28040, Spain.

Cyanobacteria often produce severe illness and in some cases spectacular fatality on livestock and wildlife world-wide. Heavy cyanobacterial waterblooms usually form patches of dense surface scum, and terrestrial animals drinking such concentrated dirty froth can consume a fatal dose. Surprisingly, animals do not avoid swallowing concentrated microbial scum. Different experiments of drink selection were performed with laboratory mice to determine why animals drink these concentrated scum. These experiments showed that animals elected to consume dense cultures of the toxic cyanobacteria Microcystis aeruginosa in preference to limpid water. When M. aeruginosa cells were supplied ad libitum, mice avidly swallowed these toxic cyanobacteria until this led to their death. Mice were unable to detect the phycotoxin (microcystin). In contrast, mice did not select cultures containing other non-toxic phytoplanktonic organisms. Observations in nature suggest that this preference in the consumption of toxic cyanobacteria is common among other animal species.

PMID: 10425250
From PubMed

Production of an emetic toxin, cereulide, is associated with a specific class of Bacillus cereus.

Agata N, Ohta M, Mori M.

Nagoya City Public Health Research Institute, Japan.

The emetic toxin (cereulide) of Bacillus cereus was quantified in several isolates of B. cereus and in various food sources. When the emetic toxin was produced, vomiting-type food poisoning was observed in humans. We also found that the H-1 serovar phenotype was strongly associated with the production of cereulide and that none of the isolates that hydrolyzed starch or expressed diarrheal enterotoxin activity produced cereulide.

PMID: 8661692
From PubMed

Hepatic ultrastructural changes induced by the toxin microcystin-LR (MCLR) in mice.

Hermansky SJ, Markin RS, Fowler EH, Stohs SJ.

Creighton University Health Sciences Center, Omaha, NE 68178.

Microcystin-LR (MCLR) is a cyclic heptapeptide produced by the blue-green algae Microcystis aeruginosa. It is highly toxic and causes death in rodents due to hypovolemic shock with associated intrahepatic hemorrhage. The molecular mechanism of toxicity is unknown. In order to provide additional information regarding the toxicity of MCLR, the ultrastructural changes present in livers of mice following the administration of 100 micrograms MCLR/kg intraperitoneally, (i.p.) were examined. Time-dependent changes were observed. Disruption of cell to cell contact occurred with infiltration of erythrocytes 60 min after MCLR treatment. Hepatocyte distortion, mitochondrial aggregation, and the prominent accumulation of large areas of endoplasmic reticulum were observed. No detectable hepatic changes in sinusoidal endothelial cells were present. The results suggest that MCLR preferentially affects hepatocytes, although the observations do not preclude the involvement of hepatic vasculature in the toxicity of MCLR.

PMID: 8189358
From PubMed

Detection and quantification of microcystins (cyanobacterial hepatotoxins) with recombinant antibody fragments isolated from a naive human phage display library.

McElhiney J, Lawton LA, Porter AJ.

Department of Molecular and Cell Biology, Institute of Medical Sciences, University of Aberdeen, Foresterhill, UK.

Single-chain antibody fragments against the cyanobacterial hepatotoxin microcystin-LR were isolated from a naive human phage display library and expressed in Escherichia coli. In competition enzyme-linked immunosorbent assay (ELISA), the most sensitive antibody clone selected from the library detected free microcystin-LR with an IC(50) value of 4 microM. It was found to cross react with three other microcystin variants - microcystin-RR, microcystin-LW and microcystin-LF - and detected microcystins in extracts of the cyanobacterium Microcystis aeruginosa, found to contain the toxins by high-performance liquid chromatography (HPLC). The quantification of microcystins in these extracts by ELISA and HPLC showed good correlation. Although the antibody isolated in this study was considerably less sensitive than the polyclonal and monoclonal antibodies already available for microcystin detection, phage display technology represents a cheaper, more rapid alternative for the production of anti-microcystin antibodies than the methods currently in use.

PMID: 11094283
From PubMed

Joint FAO/WHO Geneva consultation--acute dietary intake methodology.

Crossley SJ.

Australia New Zealand Food Authority, Barton ACT, Australia. steve.crossley@anzfa.gov

Significant developments have been made at the international level in the methodology for conducting dietary risk assessments. The existing chronic exposure assessment methodology has been updated so that it takes account of the level of residues to which consumers are most likely to be exposed. In addition, short-term exposure assessment methodology has also been developed. This uses portion size data and takes account of the variability in residue levels between individual units where this is appropriate to the way the commodity is consumed. Other refinements to the assessment can also be made. Although the short-term methodology has been used successfully by a number of regulatory authorities, there is a need for data on portion sizes and typical unit weights before it can be fully implemented internationally.

PMID: 10983578
From PubMed

Oral dietary supplements before and after surgery.

Hessov I.

Department of Surgery, Aarhus University Hospital, Denmark.

Publication Types:

• Editorial

PMID: 10978860
From PubMed

Lead in calcium supplements.

Scelfo GM, Flegal AR.

Environmental Toxicology, University of California, Santa Cruz, CA 95064, USA. gscelfo@es.ucsc.edu

Intercalibrated measurements of lead in calcium supplements indicate the importance of rigorous analytical techniques to accurately quantify contaminant exposures in complex matrices. Without such techniques, measurements of lead concentrations in calcium supplements may be either erroneously low, by as much as 50%, or below the detection limit needed for new public health criteria. In this study, we determined the lead content of 136 brands of supplements that were purchased in 1996. The calcium in the products was derived from natural sources (bonemeal, dolomite, or oyster shell) or was synthesized and/or refined (chelated and nonchelated calcium). The dried products were acid digested and analyzed for lead by high resolution-inductively coupled plasma-mass spectrometry. The method's limit of quantitation averaged 0.06 microg/g, with a coefficient of variation of 1.7% and a 90-100% lead recovery of a bonemeal standard reference material. Two-thirds of those calcium supplements failed to meet the 1999 California criteria for acceptable lead levels (1.5 microg/daily dose of calcium) in consumer products. The nonchelated synthesized and/or refined calcium products, specifically antacids and infant formulas, had the lowest lead concentrations, ranging from nondetectable to 2.9 microg Pb/g calcium, and had the largest proportion of brands meeting the new criteria (85% of the antacids and 100% of the infant formulas).

PMID: 10753088
From PubMed

Health effects of exposure to cyanobacteria (blue-green algae) during recreational water-related activities.

Pilotto LS, Douglas RM, Burch MD, Cameron S, Beers M, Rouch GJ, Robinson P, Kirk M, Cowie CT, Hardiman S, Moore C, Attewell RG.

National Centre for Epidemiology and Population Health, Australian National University, Canberra. tbutl@doh.health.nsw.gov.au

The aim of this study was to investigate effects on health of exposure to cyanobacteria as a result of recreational water activities. Participants, who were aged six years and over, were interviewed at water recreation sites in South Australia, New South Wales and Victoria on selected Sundays during January and February 1995. Telephone follow-up was conducted two and seven days later to record any subsequent diarrhoea, vomiting, flu-like symptoms, skin rashes, mouth ulcers, fevers and eye or ear irritations. On the Sundays of interview, water samples from the sites were collected for cyanobacterial cell counts and toxin analysis. There were 852 participants, of whom 75 did not have water contact on the day of interview and were considered unexposed. The 777 who had water contact were considered exposed. No significant differences in overall symptoms were found between the unexposed and exposed after two days. At seven days, there was a significant trend to increasing symptom occurrence with duration of exposure (P = 0.03). There was a significant trend to increasing symptom occurrence with increase in cell count (P = 0.04). Participants exposed to more than 5000 cells per mL for more than one hour had a significantly higher symptom occurrence rate than the unexposed. Symptoms were not correlated with the presence of hepatotoxins. These results suggest symptom occurrence was associated with duration of contact with water containing cyanobacteria, and with cyanobacterial cell density. The findings suggest that the current safety threshold for exposure of 20,000 cells per mL may be too high.

PMID: 9470258
From PubMed

Bioaccumulation and clearance of microcystins from salt water mussels, Mytilus edulis, and in vivo evidence for covalently bound microcystins in mussel tissues.

Williams DE, Dawe SC, Kent ML, Andersen RJ, Craig M, Holmes CF.

Department of Chemistry and Oceanography, University of British Columbia, Vancouver, Canada.

Over a period of 3 days saltwater mussels, Mytilus edulis, were fed a cyanobacteria, Microcystis aeruginosa, that contained a high concentration of microcystins. The mussels were killed on a periodic basis over the course of 2 months. Mussels were also collected at two sites were high levels of microcystins in tissues had been noted. A strategy based on the chemically unique nature of the C20 beta-amino acid, (2S,3S,8S,9S)-3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6- dienoic acid (Adda), portion of the microcystins was used in conjunction with a protein phosphatase (PPase) assay to analyse for both covalently bound microcystins and free microcystins in the mussel tissues. The mussel PPase assay results were compared with the Lemieux oxidation gas chromatography-mass spectrometry (GCMS) analysis. Less than 0.1% of the total microcystin burden in the mussel tissue was found to be extractable with MeOH. Thus, direct evidence was provided for the existence of covalently bound microcystins in mussel tissues in vivo. The mussels rapidly cleared the covalently bound microcystins when transferred to untreated seawater. Within 4 days the total microcystin burden dropped from a high of 336.9 (+/- 45.8) micrograms/g wet tissue to 11.3 (+/- 2.6) micrograms/g. After 4 days postexposure until completion of the experiment the total levels remained below the detection limits of the GCMS method. The levels of free microcystins, extracted with MeOH and detected by the PPase assay, fell from 204 ng/g wet tissue to a residual 14 ng/g over a 53 day postexposure period. Presumably the bound microcystin present in the mussel tissue exists as a covalent complex with the PP-1 and PP-2A enzymes. We conclude that in any shellfish monitoring program it is the total tissue microcystin burden that needs to be considered.

PMID: 9428108
From PubMed

Neoplastic nodular formation in mouse liver induced by repeated intraperitoneal injections of microcystin-LR.

Ito E, Kondo F, Terao K, Harada K.

Research Center for Pathogenic Fungi and Microbial Toxicoses, Chiba University, Japan.

Neoplastic nodules were observed in mice liver treated with microcystin-LR (MCLR) by the intraperitoneal (i.p.) route over 28 weeks. After 100 i.p. injections of a sublethal dose (20 micrograms/kg) of MCLR, neoplastic nodules were observed without the use of an initiator. Multiple neoplastic nodules up to 5 mm in diameter were observed in the liver of mice in both groups, i.e. those injected 100 times i.p. and those injected 100 times with a 2 month withdrawal. The cysteine conjugate of MCLR was detected mainly in the affected livers. In contrast, when 80 micrograms/kg was orally administered 100 times, characteristic chronic injuries such as fibrous changes and nodule formation were not observed.

PMID: 9403968
From PubMed

[Blue-green algae as a cause of human disease].

Martin PR.

[Article in Norwegian]

Fylkeslegen i Buskerud, Drammen.

Blue-green algae can cause significant public health problems. There is an abundance of scientific literature on their effects, but much of it either reports laboratory studies of toxicological effects or discusses practical problems affecting water supply. There are many reports of poisonings of farm animals and wildlife, and a number of reports of adverse health effects in humans, but the effects of blue-green algae on human health do not seem to have attracted serious attention amongst practising physicians. It is probable that the occurrence of blue-green algae in algal blooms in the aquatic environment, often with production of toxins, will continue to increase as a result of human activity. It thus seems important that clinicians should become more aware of their effects. On this background the author briefly summarizes proven and potential adverse effects on health.

Publication Types:

• Journal Article
• Review
• Review, Tutorial

PMID: 8079249
From PubMed

From herbal Prozac to Mark McGwire's tonic: how the Dietary Supplement Health and Education Act changed the regulatory landscape for health products.

Kaczka KA.

PMID: 10970182
From PubMed

First report on the distribution of orally administered microcystin-LR in mouse tissue using an immunostaining method.

Ito E, Kondo F, Harada K.

Research Center for Pathogenic Fungi and Microbial Toxicoses, Chiba University, Japan.

The purpose of this study was to investigate the distribution of microcystin-LR (MCLR) orally administered to mice using an immunostaining method. MCLR was orally dosed at 500 microg/kg to aged Balb/C and ICR mice and their lethality was 23.9%. The former was more sensitive to MCLR than the latter, suggesting that oral toxicity by MCLR is related to the animal strains tested, although the pathological and immunostaining changes were essentially the same in both strains. According to this method the distribution of MCLR and related compounds were indicated as the red staining. Particularly, livers of dead aged mice were intensively stained. The main route of absorption was considered to be the small intestine because the villi contained a large amount of MCLR in both surface epithelial cells and lamina propria, resulting in erosion. The absorbed MCLR was contained in blood plasma and moved to the liver, lung, and heart, and finally to capillaries of the whole body. Excretion of MCLR was shown in the mucous from goblet cells in both the small intestine and large intestine.

PMID: 10669010
From PubMed

Microcystin production by Microcystis aeruginosa in a phosphorus-limited chemostat.

Oh HM, Lee SJ, Jang MH, Yoon BD.

Environmental Microbiology Research Unit, Korea Research Institute of Bioscience and Biotechnology, Yusong, Taejon 305-600, Korea. heemock@mail.kribb.re

The production of microcystins (MC) from Microcystis aeruginosa UTEX 2388 was investigated in a P-limited continuous culture. MC (MC-LR, MC-RR, and MC-YR) from lyophilized M. aeruginosa were extracted with 5% acetic acid, purified by a Sep-Pak C(18) cartridge, and then analyzed by high-performance liquid chromatography with a UV detector and Nucleosil C(18) reverse-phase column. The specific growth rate (mu) of M. aeruginosa was within the range of 0.1 to 0.8/day and was a function of the cellular P content under a P limitation. The N/P atomic ratio of steady-state cells in a P-limited medium varied from 24 to 15 with an increasing mu. The MC-LR and MC-RR contents on a dry weight basis were highest at mu of 0.1/day at 339 and 774 microg g(-1), respectively, while MC-YR was not detected. The MC content of M. aeruginosa was higher at a lower mu, whereas the MC-producing rate was linearly proportional to mu. The C fixation rate at an ambient irradiance (160 microeinsteins m(-2) s(-1)) increased with mu. The ratios of the MC-producing rate to the C fixation rate were higher at a lower mu. Accordingly, the growth of M. aeruginosa was reduced under a P limitation due to a low C fixation rate, whereas the MC content was higher. Consequently, increases in the MC content per dry weight along with the production of the more toxic form, MC-LR, were observed under more P-limited conditions.

PMID: 10618220
From PubMed

Effect of microcystin on growth of single species and on mixed natural populations of heterotrophic nanoflagellates.

Christoffersen K.

Freshwater Biological Laboratory, University of Copenhagen, Hillerod, Denmark.

Natural populations of heterotrophic nanoflagellates were reduced in numbers and in situ growth rates during a toxic Microcystis bloom in a eutrophic lake. Microcystin was found in the particulate phase (algae) and in the dissolved phase (water) with maximum concentrations of 414 micrograms g freeze-dried algal material-1 and 141 micrograms l-1 lake water, respectively. An average reduction in growth rates of 49% was found when comparing the growth estimates before and after the toxic bloom had peaked. Similar reductions were found in laboratory experiments when growing mixed flagellate populations from two different systems with microcystin, but without predators. Concentrations of 10 micrograms toxin 1-1 reduced the growth rates by 36-41% (significantly different from the controls) and 1 microgram toxin 1-1 reduced the growth rates by 24-28% (not significant). Thus, natural populations of heterotrophic nanoflagellates seem very sensitive to microcystin. The growth characteristic of two cultured species was also tested in the presence of microcystin. Both the cultured species, Heteromita globosa and Spumella sp., grew well at 1-10 micrograms microcystin 1-1 and Spumella sp. was able to grow at 50 micrograms microcystin 1-1. However, the growth curves indicate that the decline in numbers during the stationary phase occurred faster in the presence of microcystin. The ecological consequences of a highly sensitive protozoan community may be that larger zooplankton species (copepods and cladocerans) are affected by reduced availability of food.

PMID: 8946396
From PubMed

Viability changes in human neutrophils and monocytes following exposure to toxin extracted from Aphanizomenon flos-aquae.

Barton LL, Foster EW, Johnson GV.

An in vitro method for detecting toxin produced by Aphanizomenon flos-aquae is described. This procedure is more sensitive than the mouse toxicity test and is based on viability changes in human leukocytes.

PMID: 6773647
From PubMed

NIH studying dietary supplements for arthritis.

[No authors listed].

Publication Types:

• News

PMID: 10932950
From PubMed

The frustrations of fighting foodborne disease.

Tamblyn SE.

Department of Epidemiology and Biostatistics, University of Western Ontario, London. tamblyn@pdhu.on.ca

PMID: 10834046
From PubMed

Development and evaluation of a PCR-microplate capture hybridization method for direct detection of verotoxigenic Escherichia coli strains in artificially contaminated food samples.

Cocolin L, Astori G, Manzano M, Cantoni C, Comi G.

Dipartimento di Scienze degli Alimenti, Facolta' di Agraria, Universita' di Udine, Italy.

For the purpose of detecting, directly in food, verotoxigenic Escherichia coli, a microplate hybridization method for the detection of PCR products from the SLT I and SLT II genes, was developed and evaluated. Two pairs of primers and two probes, specific for the SLT I gene and for the SLT II gene, were designed and tested. For the strains containing both genes, two PCR products of different molecular weights were obtained, whereas when only one gene was present only one fragment resulted from PCR. The use of the biotin-labeled probes allowed the immobilization of the PCR products in the microtiter plate wells and by this means their detection was possible using an ELISA-based technique. Forty artificially contaminated and fifty naturally contaminated food samples were analyzed by using the PCR-microplate hybridization technique developed in this study. All the artificially contaminated food samples were positive, independently of the number of cells inoculated before the enrichment step, whereas the naturally contaminated food samples were all negative.

PMID: 10746569
From PubMed

The Mayo Clinic doctor. Pass the Vitameatavegamin.

Hensrud DD.

Publication Types:

• News

PMID: 10977338
From PubMed

Adsorption of the cyanobacterial hepatotoxin microcystin-LR by a low-cost activated carbon from the seed husks of the pan-tropical tree, Moringa oleifera.

Warhurst AM, Raggett SL, McConnachie GL, Pollard SJ, Chipofya V, Codd GA.

Department of Civil and Environmental Engineering, University of Edinburgh, UK.

A low-cost activated carbon from the pan-tropical multipurpose tree Moringa oleifera removes the cyanobacterial hepatotoxin microcystin-LR in quantitative amounts from water in batch adsorption trials. The potential of M. oleifera seed husk carbon for cyanobacterial toxin removal in drinking water treatment in tropical countries is discussed.

PMID: 9447749
From PubMed

Degradation of the cyanobacterial hepatotoxin, nodularin, under light and dark conditions.

Twist H, Codd GA.

Department of Biological Sciences, University of Dundee, Scotland, UK.

The stability of the cyanobacterial hepatotoxin, nodularin, was determined during the incubation of purified toxin, and in nodularin-containing cell-free extracts and whole filaments of the nodularin-producer, Nodularia spumigena in sunlight and darkness. Levels of purified nodularin in aqueous solution remained approximately constant throughout the 9-day trials under all conditions, but decreased in cell-free extracts and whole filaments when incubated under all conditions, with losses being greatest in full sunlight, intermediate in sunlight minus ultraviolet wavelengths and lowest in continuous darkness. Photodegradation and detoxification in Artemia salina bioassays occurred when purified nodularin was irradiated with ultraviolet wavelengths using a laboratory lamp.

PMID: 9198286
From PubMed

Evidence for a covalently bound form of microcystin-LR in salmon liver and Dungeness crab larvae.

Williams DE, Craig M, McCready TL, Dawe SC, Kent ML, Holmes CF, Andersen RJ.

Department of Chemistry, University of British Columbia, Vancouver, Canada.

The chemically unique nature of the C20 beta-amino acid (2S,3S,8S,9S)-3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6- dienoic acid (Adda) portion of the microcystins has been exploited to develop a strategy to analyze for the total microcystin-LR (1; see Figure 1) burden in salmon liver and crab larvae tissues. Lemieux oxidation of microcystin-LR (1) gives 2-methyl-3-methoxy-4-phenylbutanoic acid (2), a unique marker for the presence of microcystins. The butanoic acid 2 can be isolated and detected by GC/MS from the livers of Atlantic salmon that received an ip injection of microcystin-LR (1) and from tissues of wild-caught crab larvae. The Lemieux oxidation-GC/MS results are compared with those from MeOH extraction-PPase analysis. Only approximately 24% of the total microcystin-LR (1) burden in salmon liver tissue is found to be extractable with MeOH. Similarly, the Lemieux oxidation-GC/MS method detected 10,000-fold greater microcystin concentrations in Cypress Island Dungeness crab larvae than did the MeOH extraction-PPase method. The disparity in microcystin concentrations measured by the two methods is taken as direct evidence for the existence of covalently bound microcystins in vivo.

PMID: 9114985
From PubMed

Hemagglutination method for detection of freshwater cyanobacteria (blue-green algae) toxins.

Carmichael WW, Bent PE.

Strains of the freshwater cyanobacteria (blue-green algae) Anabaena flosaquae and Microcystis aeruginosa produced toxins that caused intermittent but repeated cases of livestock, waterfowl, and other animal deaths. They also caused illness, especially gastrointestinal, in humans. The most common group of toxins produced by these two species were peptide toxins termed microcystin, M. Aeruginosa type c, and anatoxin-c. A method was found to detect the toxins which utilizes their ability to cause agglutination of isolated blood cells from mice, rats, and humans. The method could detect the toxin in samples from natural algal blooms, laboratory cultures, and toxin extracts. The method consists of: (i) washing lyophilized cyanobacteria cells with physiological saline (0.9% NaCl), (ii) centrifuging the suspension and then mixing portions of the cell-free supernatant with equal volumes of saline-washed erythrocytes in V-shaped microtiter plates, (iii) allowing the mixture to stand for 3 to 4 h, and (iv) scoring the presence of the toxin as indicated by blood cell agglutination. Nontoxic strains, as determined by intraperitoneal mouse bioassay of cyanobacteria or green algae, did not produce an agglutination response.

PMID: 6787984
From PubMed

Functional foods and health claims: a public health policy perspective.

Lawrence M, Rayner M.

Division of Public Health and Primary Health Care, University of Oxford, UK. malawren@deakin.edu.au

OBJECTIVE: To propose a policy framework for the regulation of functional foods and health claims within a public health context. DESIGN: This article reviews the empirical evidence and public health principles associated with functional foods and health claims to analyse the issues, challenge the assumptions that have emerged and explore options for moving forward. SETTING: Functional foods and health claims are among the more controversial and complex issues being debated by food regulators internationally. Proponents of functional foods and health claims state that functional foods may reduce health care expenditure and health claims are a legitimate nutrition education tool that will help them inform consumers of the health benefits of certain food products. Conversely, opponents of these developments respond that it is the total diet that is important for health, not so-called 'magic bullets'. Moreover, they argue that health claims will enable manufacturers to indulge in marketing hyperbole and essentially blur the distinction between food and drugs. This topic provides a valuable case study of public policy in relation to food and health. CONCLUSION: The need to maintain a general prohibition on health claims while accommodating specific exemptions supported by scientific substantiation is recommended. Nutrition education and monitoring and evaluation are integral to the proposed regulatory framework. The intention of this policy position is to encourage research and development of innovative food products while avoiding an inappropriate medicalization of the general food supply.

Publication Types:

• Journal Article
• Review
• Review, Tutorial

PMID: 10933403
From PubMed

Teratology society: presentation to the FDA public meeting on safety issues associated with the use of dietary supplements during pregnancy.

Friedman JM.

Department of Medical Genetics, University of British Columbia, Vancouver, Canada V6T 1Z2.

Publication Types:

• Congresses

PMID: 10931511
From PubMed

Uncertain quality of dietary supplements: history repeated.

Hasegawa GR.