To assess the prevalence of and risk factors for low bone mineral density in inflammatory bowel disease (IBD)

A survey of the occurrence of toxic blooms of cyanobacteria in Finnish fresh and coastal waters was made during 1985 and 1986. Toxicity of the freeze-dried water bloom samples was tested by mouse-bioassay (i.p.). Forty-four per cent (83/188) of the bloom samples were found to be lethally toxic. Hepatotoxic blooms (54) were almost twice as common as neurotoxic ones (29). Anabaena was the most frequently found genus in toxic and non-toxic blooms and it was present in all neurotoxic samples. Statistical associations were found between hepatotoxicity and incidence of Microcystis aeruginosa, M. viridis, M. wesenbergii, Anabaenaflos-aquae and Anabaena spiroides. Neurotoxicity was statistically associated with Anabaena lemmermannii, Anabaenaflos-aquae and Gomphosphaeria naegeliana. Isolation of strains of cyanobacteria confirmed the occurrence of hepatotoxic and neurotoxic strains of Anabaena, as well as hepatotoxic strains of Microcystis and Oscillatoria species.Toxic blooms caused cattle poisonings at three different lakes during the study period. Toxic blooms also occurred in drinking water sources. Our study shows that toxic cyanobacteria are more common in Finnish lakes than would be expected on the basis of animal poisonings. The results of this study show the existence of toxic cyanobacteria in Finnish water supplies and the need for their continued study as agents of water based disease.

Water blooms formed by potentially toxic species of cyanobacteria are a common phenomenon in the Baltic Sea in late summer. Twenty-five cyanobacterial bloom samples were collected from open and coastal waters of the Baltic Sea during 1985 to 1987, and their toxicity was determined by mouse bioassay. All of 5 bloom samples from the southern Baltic Sea, 6 of 6 from the open northern Baltic Sea (Gulf of Finland), and 7 of 14 Finnish coastal samples were found to contain hepatotoxic cyanobacteria. Nodularia spumigena and Aphanizomenon flos-aquae occurred together in high amounts in blooms from the open-sea areas. In addition, coastal samples contained the species Anabaena lemmermannii, Microcystis aeruginosa, and Oscillatoria agardhii. Eighteen hepatotoxic N. spumigena cultures were isolated from water bloom and open-sea water samples. High-pressure liquid chromatographic analysis of both hepatotoxic bloom samples and Nodularia strains showed a single toxic fraction. The toxin concentrations of the blooms were .2.4 mg/g of freeze-dried material, and those of laboratory-grown cultures were 2.5 to 8.0 mg/g of freeze-dried cells. A single toxin was isolated from three N. spumigena-containing bloom samples and three N. spumigena laboratory isolates. Amino acid analysis and lowand high-resolution fast-atom bombardment mass spectroscopy indicated that the toxin from all of the sources was a cyclic pentapeptide (molecular weight, 824) containing glutamic acid, I-methylaspartic acid, arginine, N-methyldehydrobutyrine, and 3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-4,6-decadienoic acid. This indicates that the Baltic Sea toxin is nodularin, the cyclic pentapeptide produced by field and laboratory-cultured N. spumigena previously reported from New Zealand brackish water lakes. The signs of poisoning by the pentapeptide were similar to those reported for the heptapeptide toxins from other cyanobacteria.

No abstract

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°C), together with the highest levels of light studied (test range, 2 to 100 mol 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°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 mol 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.