Showing papers in "Journal of Toxicology-toxin Reviews in 2001"

Distribution and origin of tetrodotoxin

Abstract: Among the marine toxins relevant for human intoxication, tetrodotoxin (TTX) has been known as one of the most prejudicial. Puffer fish were originally thought to be the only animal from which TTX could be isolated. Subsequent works determined that TTX also existed in a range of marine organisms of different phylogenic classes and a very few amphibians. The production of TTX is generally accepted to be associated with bacteria. This paper presents the current evidences for the distribution of TTX and its analogs in several vertebrates and invertebrates, along with the probable origin of TTX.

Puffer poisoning: epidemiology and treatment

Abstract: Tetrodotoxin (TTX) intoxication resulting from the ingestion of toxic puffer is relatively common in a number of Asian countries. In Japan, 100 annual human fatality due to ingestion of toxic puffer have been reported until 1960. Poisoning incidents, however, decreased in the recent years by imposing quarantine rule and creating public awareness after extensive study of the toxicity and toxin properties of puffer. Generally, the oral paresthesia is the initial symptom of puffer poisoning. The onset of symptoms is rapid. In spite of long history of TTX intoxication, no antidotes or antitoxins to TTX is invented so far. Treatment is supportive.

Pharmacology of tetrodotoxin

Abstract: Tetrodotoxin (TTX) is a potent neurotoxin originally found in the ovary and liver of puffer fish. It has now become abundantly clear that TTX is not synthesized in the puffer fish, and that it is p...

Chemistry of puffer fish toxin

Abstract: Tetrodotoxin (TTX) is well known as the puffer fish toxin. Naturally occurring analogs of TTX have been isolated from puffer fish, newts and frogs, and their structures have been determined by spectroscopic methods. Additionally, TTX analogs have been prepared by chemical modification to investigate its binding site on sodium channels and the structure-activity relationship of TTX. In this article, the NMR data of TTX analogs are listed, and the chemical modification methods for preparation of TTX probes are summarized.

Ciguatera fish poisoning: review of clinical manifestations

Abstract: Ciguatera is a complex clinical syndrome, caused by a marine biotoxin, which can affect nearly every system of the human body. The clinical syndrome has characteristic elements in its acute, chronic and recurring forms. The incidence of ciguatera is on the rise, and misdiagnosis is not uncommon. Appropriate identification, management and treatment of ciguatera is dependent on understanding the pathophysiology of the illness, determining the correct form of the illness, and applying the appropriate treatment modalities to that form. More research is necessary to clinically manage ciguatera and the clinical dilemmas it presents.

Current methodologies for detection of tetrodotoxin

Abstract: In attempt to protect the consumers from TTX-intoxication, the mouse bioassay has historically been the most universally applied tool to determine the toxicity level in monitoring programs. This bioassay, however, shows low precision and requires a continuous supply of a particular size of mice. These potential drawbacks and the world-wide pressure of refraining from the killing of the live animals subsequently led the scientists for developing alternative chemical methods to the mouse bioassay for TTX detection and quantification. Among them, high-performance liquid chromatography (HPLC) has largely been used in routine work.

Ochratoxin a in the czech republic

Abstract: Ochratoxin A (OTA) was found in cereals in the former Czechoslovakia as early as 1978. It was even the cause of mycotoxic nephropathy in pigs in a farm in the second half of the 1970s. Since then OTA has been monitored by the health authorities of Czechoslovakia and now the Czech Republic. OTA was detected in samples of various foodstuffs e.g. composite samples of cereals, pastry, coffee and raisins. OTA was also found in the blood serum of blood donors. A recent study of the accumulation of OTA in patients with chronic renal insufficiency (CHRI) has demonstrated that unlike in the control group of blood donors, the retention of OTA is significant in outpatients with stabilized CHRI and patients in the terminal stage of CHRI (who are regularly treated by dialysis). Because of the nephrotoxicity of OTA, such a retention may accelerate their disease. The study has also shown that a standard dialysis did not result in the decrease of OTA serum levels. Findings of OTA in biological materials have proven that ...

Ciguatera fish poisoning: a foodborne disease

Abstract: This review is an extensive up-to-date compilation of ciguatera fish poisoning, a food borne disease, which covers all aspects of the problem, with the exception of clinical and therapeutic information. Thus brief accounts of the history, biology, chemistry, pharmacology, epidemiology, detection methods, pathology, and comprehensive references are presented.

Toxin evolution in scorpion venom: evidence for toxin divergence under strong negative selection in leiurus quinquestriatus subspecies

Abstract: The Buthid scorpion Leiurus quinquestriatus is divided into two sub-species whose region of contact occurs at the Suez Isthmus. L.q. quinquestriatus, found in the North Africa is distinguished from L.q. hebraeus by minor differences in morphology. Despite the very high similarity in body plan, out of the 24 toxins isolated from this species none is common to both sub-species, suggesting a degree of molecular divergence not apparent at the morphological level. We show, by comparison with two sets of reference proteins from humans and Old-World monkeys, that divergence of toxins with common structures and functions in these two sub-species has occurred under conditions of strong negative selection. Potential selection pressures responsible for toxin divergence are discussed, including the role of conflicting interests during courtship.

Mechanically processing cottonseed to reduce gossypol and aflatoxin levels

Abstract: Cottonseed is an economical source of protein and is commonly used in balancing livestock rations; however, its use is typically limited by protein level, fat content, gossypol, and the potential for aflatoxin contamination. There are numerous studies in the literature discussing gossypol and aflatoxin toxicities in livestock and processing methods for reducing gossypol levels in cottonseed. However, there is very limited information in the literature within the last 30 years on how aflatoxin is affected by processing. Evaluation studies were conducted to determine if an extrusion process affected gossypol and aflatoxin levels in cottonseed without negatively impacting the nutritional value of the product, and if these reductions were consistent with the literature. Results from the gossypol study showed a 71 to 78% decrease in free gossypol levels due to the extrusion process, which were lower than some reported methods of processing and consistent with others. Results from the aflatoxin studies showed reductions of 50% when the material was processed by two stages of extrusion at a temperature of 132°C. Similar reductions have been reported on roasting corn at temperatures of 140 to 143°C. The extrusion temperatures used in the evaluation studies did not significantly alter most of the nutritional values analyzed in the study. However, soluble protein was decreased at the higher temperatures. There were no significant differences in analyzed nutritional values based on multiple stages of processing. Results from the evaluation study indicate that extruding cottonseed to reduce gossypol and aflatoxin levels is an area of research that should be further explored, primarily due to the advances made in the aflatoxin and gossypol testing methods during the last 30 years.

Reactive astrocytic response and increased proliferating cell nuclear antigen expression in cerebral cortex of envenomed rats

Abstract: The regional distribution and the appearance of astrocytes expressing glial fibrillary acidic protein (GFAP), S100 protein, and proliferating cell nuclear antigen (PCNA) were determined in the cerebral cortex of normal and cobra venom intoxicated rats. Male rats were divided to three groups intramuscularly treated with a single injection of either physiological saline solution or ½ LD50 or LD50 of cobra venom respectively. Formalin-fixed paraffin-embedded brain sections of animals of the three groups were immunohistochemically studied according to avidin-biotin-peroxidase complex method using antibodies against GFAP, S100 protein and PCNA. As biomarkers of cerebral neurotoxicity, dose and time dependent increases in the expression of GFAP and S100 protein were observed. Marked increases in the expression of GFAP and S100 protein were common in high dose (LD50) envenomed rats 72 h after venom injection, whereas in low dose (½ LD50) envenomed rats only moderate increases of these two proteins were detected ...

Glycosidases in venoms

Abstract: Animal venoms are rich sources of enzymes. Most enzymes found in animal venom are hydrolytic enzymes. A notable exception is L-amino acid oxidase, which is responsible for the yellow color of snake venom. Although a variety of enzymes are present in venom, only a few types have been extensively studied, most notably, proteolytic enzymes and phospholipase A2. There have been relatively few investigations on glycosidases in venom. Practically all studies on venom glycosidases have involved hyaluronidase. In addition, there are a few investigations on nicotinamide adenine nucleotidase (NADase), and polyand disaccharidases. An extensive review of venom glycosidases is presented here in order to provide an overall picture of this class of enzymes. Since hyaluronidase is more extensively investigated than other venom enzymes, it will be discussed in more detail.

Modification of biological properties of protein toxins by stepwise iodination

Abstract: By gradual incorporation of stable iodine into toxins and whole venoms it is possible to abolish completely the physiological, lesion and lethal properties of the native components. The properties of iodinated antigens and from antibodies generated by these detoxified derivatives, are presented. The hapten is incorporated into tyrosyl and histidyl residues. The derivatives can be obtained in less than one hour. Within the same batch of protein, there is a determinable stoichiometric ratio hapten/protein to achieve the desired modified properties of the derivative. The iodinating solutions are easy to prepare, can be accurately standardized and have unlimited shelf lives. The cost of the whole procedure is very low. No side-effects, local or systemic were observed, even with prolonged use of the derivatives. The method was applied to toxic components and whole venom of the scorpion Tityus serrulatus, and the hypertensive, bradipneic, oliguric, lesional, lethal and cytotoxic effects were completely abolishe...