OBJECTIVETo develop an ICR (female) mouse bioassay (MBA) for toxicity confirmation and evaluation of neurotoxins (brevetoxins)-contaminated shellfish.

METHODSBrevetoxins (BTX-B) as a causative agent of neurotoxic shellfish poisoning (NSP) under different shellfish matrices were intraperitoneally injected at different doses into mice to study their toxic effects and to differentiate the range of lethal and sublethal dosages. Their sensitivity and specificity were analyzed with 2 competitive ELISA kits for quantitative determination of standard BTX-B and dihydroBTX-B under different shellfish matrix-diluent combinations. Detection rates of MBA and two antibody-based assays for BTX-B from field NSP-positive shellfish samples were compared.

RESULTSBTX-B could be detected in shellfish tissues at concentration of 50-400 μg/100 g under shellfish matrix-Tween-saline media, which were appropriate to identify toxic shellfish at or above the regulatory limit (80 μg/100 g shellfish tissues). The LD50 identified was 455 mg/kg for BTX-B under general shellfish matrices (excluding oyster matrices) dissolved in Tween-saline. The presence of shellfish matrices, of oyster matrices in particular, retarded the occurrence of death and toxicity presentation in mice. Two antibody-based assays, even in the presence of different shellfish matrix-diluent combinations, showed acceptable results in quantifying BTX-B and dihydroBTX-B well below the regulatory limit.

CONCLUSIONThe two ELISA analyses agree favorably (correlation coefficient, r³⋝0.96; Student's t-tests, P>0.05) with the developed bioassay.

Animals ; Biological Assay ; Calibration ; Female ; Marine Toxins ; toxicity ; Mice ; Mice, Inbred ICR ; Oxocins ; toxicity ; Shellfish ; analysis

OBJECTIVETo study the cytotoxicity of maitotoxin (MTX) and its protective effects on calcium-channel blocking agents, so as to provide the data for control and treatment of MTX poisoning.

METHODSCytotoxicity was measured by MTT detecting system, and cytoplasmic free [Ca(2+)]i was measured by F-4500 fluorometry.

RESULTSIncubation with 8 ng/ml MTX for 3 h reduced the survival ratio of LLC-PK(1) cells. The response was found in a time- and concentration-dependent manner, with significant differences as compared with the control group. The MTX-induced increase in [Ca(2+)]i was inhibited by Verapamil and Nifedipine at 5 x 10(-5) mol/L and 1 x 10(-4) mol/L respectively. Both of them significantly reduced the death of the LLC-PK(1) cells.

CONCLUSIONSCytotoxicity of MTX may be caused by the elevated intracellular [Ca(2+)]i. Calcium-channel blocking agents could protect LLC-PK(1) cells from injury by MTX.

Animals ; Calcium ; metabolism ; Calcium Channel Blockers ; pharmacology ; Drug Antagonism ; LLC-PK1 Cells ; Marine Toxins ; toxicity ; Nifedipine ; pharmacology ; Oxocins ; Swine ; Verapamil ; pharmacology

The frequency and scale of Harmful Algal Bloom (HAB) and marine algal toxin incidents have been increasing and spreading in the past two decades, causing damages to the marine environment and threatening human life through contaminated seafood. To better understand the effect of HAB and marine algal toxins on marine environment and human health in China, this paper overviews HAB occurrence and marine algal toxin incidents, as well as their environmental and health effects in this country. HAB has been increasing rapidly along the Chinese coast since the 1970s, and at least 512 documented HAB events have occurred from 1952 to 2002 in the Chinese mainland. It has been found that PSP and DSP toxins are distributed widely along both the northern and southern Chinese coasts. The HAB and marine algal toxin events during the 1990s in China were summarized, showing that the HAB and algal toxins resulted in great damages to local fisheries, marine culture, quality of marine environment, and human health. Therefore, to protect the coastal environment and human health, attention to HAB and marine algal toxins is urgently needed from the environmental and epidemiological view.
Amnesia ; chemically induced ; Animals ; China ; epidemiology ; Ciguatoxins ; toxicity ; Diarrhea ; chemically induced ; Dinoflagellida ; Environment ; Eukaryota ; chemistry ; Eutrophication ; Fisheries ; Food Contamination ; Foodborne Diseases ; epidemiology ; etiology ; Humans ; Kainic Acid ; analogs & derivatives ; poisoning ; Lethal Dose 50 ; Marine Toxins ; chemistry ; poisoning ; toxicity ; Neurotoxicity Syndromes ; etiology ; Okadaic Acid ; poisoning ; Oxocins ; poisoning ; Paralysis ; chemically induced ; Seawater ; Shellfish Poisoning