In order to evaluate the contribution of polycyclic aromatic hydrocarbons (PAHs) to mutagenicity of concentrates from water, the adsorption, elution and recovery behavior of 26 PAHs bearing 3 to 6 rings were investigated by the Blue Chitin column method. The adsorption rates of 22 PAHs, having three or more fused rings, to Blue Chitin were over 90%. Elution rates of PAHs with 4 and 5 rings and nitroarenes (NO₂-PAHs) adsorbed on Blue Chitin were 50-70% with 100ml of methanol-ammonia (CH₃OH-NH₄OH) (50 : 1). However, elution rates of PAHs with 3 and 6 rings and aminoarenes (NH₂-PAHs) were 0-40% with 100ml of the same mixed eluate. However, additional elution with 20ml of dichloromethane (CH₂Cl₂) following the elution with 100ml of CH₃OH-NH₄OH (50 : 1) raised the elution ratio by 10-30%. Elution employing CH₂Cl₂ was thus more effective for elution of PAHs adsorbed to Blue Chitin. Using this preconcentration method on a modified Blue Chitin column, fluoranthene, pyrene, benz [a] anthracene, chrysene, benzo [b]-fluoranthene, benzo [k] fluoranthene, benzo [a] pyrene and dibenz [a, h] anthracene in effluent water and fluoranthene, pyrene and benzo [k] fluoranthene in river water were detected. In summary, this preconcentration method using a modified Blue Chitin column was useful for concentration of PAHs and NO₂-PAHs with 4 and 5 rings from environmental water.

View full abstract

To investigate the effect of lead on the synthesis of fibrinolytic proteins by vascular endothelial cells, cells obtained from human umbilical vein were exposed to the metal in a culture system. It was found that the secretion of tissue plasminogen activator (t-PA) is inhibited by lead but that of plasminogen activator inhibitor type 1 (PAI-1) was unaffected by the metal. However, gene expression of t-PA as well as PAI-1 was unaffected by lead when evaluated by quantitative reverse transcription-polymerase chain reaction. The inhibition of t-PA secretion by lead was observed even in the presence of actinomycin D, an inhibitor of mRNA synthesis. The inhibition of t-PA secretion by lead was also observed in the presence of the adenylate cyclase activator forskolin but was suppressed and disappeared in the presence of either 8-bromo adenosine 3', 5'-cyclic monophosphate that is a congener of adenosine 3', 5'-cyclic monophosphate which is resistant to degradation by phosphodiesterase or the phosphodiesterase inhibitor 1-methyl-3-isobutylxanthine. On the other hand, both the incorporation of [ ¹⁴C] leucine into the acid-insoluble fraction of endothelial cells and the leakage of lactate dehydrogenase from the cells were unchanged by lead, indicating that the metal did not cause inhibition of general protein synthesis and nonspecific cell damage. The present data suggest that lead selectively inhibits t-PA synthesis by vascular endothelial cells at the post-transcriptional level and the inhibition is mediated by activation of the cyclic AMP-dependent pathway as a result of a lower activity of phosphodiesterase.

View full abstract

Glucose was determined using an apparatus containing an enzyme reactor in a flow line. The enzymes used for glucose assay were hexokinase and glucose-6-phosphate dehydrogenase. NADH formed by enzymatic reactions was fluorometrically detected. The optimal concentrations of ATP and NAD<+> in the carrier were determined. Of the buffers examined for use as a carrier medium, triethanolamine buffer was found to be the most favorable and the optimal pH of this buffer was pH 7.0. Under these optimal conditions, the calibration curve for glucose was linear in the range of 2.0-200μM(r=0.999). Detection limit was 1.7μM(S/N=3).This method was applied to the analysis of glucose in several beverages. Glucose content determined by the present method agreed with that determined by a commercially available test-kit method. The methods for the preparation of immobilized enzymes were examined to retain the activities of enzymes.

View full abstract

Bacteria and mammalian cells show an adaptive response to oxidative stress. Pre-treatment with small amounts of oxidant induces resistance to the subsequent, otherwise lethal, doses of oxidant. Previous studies have shown that this adaptive response involves the induction of superoxide dismutase (SOD), glutathione peroxidase (GPX), metallothionein, heat shock proteins, and other factors. The toxicity of ionizing radiation, particularly at low doses, to living cells, is thought to be due to reactive oxygen species (ROS) formation. Thus, adaptive responses to low doses of ionizing radiation and to oxidants are likely to be similar. In this paper, the induction of endogenous glutathione (GSH) together with antioxidant enzymes induced by low-dose radiation was reviewed. Futhermore, the applicable possibility of this efficacy for the prevention of and / or therapy of various reactive oxygen species (ROS)-related diseases including Parkinson's diseases, aging, and diabetes, was discussed.

View full abstract

We surveyed recent outbreaks of poisoning in Japan and discussed the subjects in response to the request from emergency physicians for their research. Except for carbon monoxide poisoning, agricultural chemicals are the main cause of death by poisoning in Japan. The second most frequent cause is death by pharmaceutical substances. Moreover, there are many cases of multi-chemical poisoning caused by the complication of the above chemicals. It is clear that of the basic studies about toxicological mechanisms and the development of antidotes are both important on the basis of the management of all kinds of poisoning. Especially, the development of low molecular specific antidotes for poisoning by paraquat and organophosphates is required, because of the high mortality rate of these chemicals. The importance should be noted by the simulation studies which clarify the human kinetics of overdose cases by using the kinetic data of therapeutic doses and overdoses in animals along with the data on therapeutic doses in human cases. Furthermore, studies which predicting the effects of multi-chemical poisoning may be important : for example, the study on the changes of levels of toxic substances in the blood caused by the interaction of other chemicals. Endermic drugs expected to reduce the occurrence of pharmaceutical poisoning would be developed. The development of a new nonspecific absorbent which could be handled easily and effective in a small dose. The methods of rapid qualitative analysis for the detection of unknown toxic substances should be promoted.

View full abstract

Toxic blooms of cyanobacteria occur in eutrophicated lakes, pond and river over the world. Cyanobacteria have produced acute toxins such as hepatotoxic peptides, microcystins and nodularins, and neurotoxic alkaloids, anatoxin-a, anatoxin-a(s) and saxitoxins. Microcystis, Oscillatoria, Anabaena, Aphanizomenon and Nodularia produce these toxins and have been responsible for the death of wild and domestic animals drinking water contaminated with blooms. A new hepatotoxin, cylindrospermopsin was also isolated from Cylindrospermopsis and Umezakia. The principal species under investigation is Microcystis aeruginosa, which has been frequently cited in animal poisoning incidents and produces strongly hepatotoxic cyclic heptapeptides named microcystins. Very recently, a toxic accident of 50 person's death occurred in Brazil in 1996 due to microcystin in the water for hemodialysis. The toxins consist of seven amino acids and approximately 60 components have been isolated so far. The toxins also inhibit protein phosphatases 1 and 2A in a manner similar to okadaic acid and have a tumor-promoting activity on the rat liver. Now microcystins are threatening human health and life, and many problems associated with microcystins remains to be solved. Since the total structures of microcystins were determined in 1984 by Botes group, many results obtained from various fields have been extensively accumulated. They are mainly classified into the following categories : 1) ecological aspects including taxonomy and toxic waterbloom formation, 2) production, occurrence and fate of microcystins, 3) chemistry and detection, 4) toxicology and health effects, 5) regulation of toxic cyanobacteria and 6) water treatment for removal of microcystins. Thie review overviews mainly the recent advance of microcystin researches in addition to the Caruaru incident.

View full abstract

Total reflection X-ray fluorescence spectroscopy (TXRF) was applied to trace elemental analysis of 50 kinds of seized methamphetamines, a half of which had been classified to be pure and the remainder to be impure. As trace elements, Br, Hg, I, Ca, Fe, Cr, Mn, Ni, Cu and Zn were detected. Among them, Br was detected in all samples and its content was distributed between 0.4ng and 71ng per 1mg of methamphetamine HCl and Hg was detected in 8 samples and its content was distributed between 0.8ng and 9ng per 1mg of methamphetamine HCl. Iodine was detected in 8 samples, among which 6 samples also contained Hg. Hg and I were presumed to be derived from synthetic reagents. Iron and other heavy metals would be derived from impurities in synthetic solvents or metal containers through synthetic or smuggling processes. Elements detected in seized methamphetamines are applicable as tracing markers for the ascertainment of clandestine synthetic techniques or places to make illicit methamphetamine salts.

View full abstract

An iron regulatory protein (IRP) is an RNA-binding protein that regulates the expression of several mRNAs such as transferrin receptor (Tf-Rc) and ferritin mRNAs in response to the availability of cellular iron (Fe). IRP interacts with the iron-responsive element (IRE) in both of mRNAs to regulate the life span and to modulate the translation rate of ferritin. IRP was also identified as cytosol aconitase. We previously demonstrated that aluminum (Al)as well as Fe decrease the expression of Tf-Rc mRNA in rat cortical cells treated with Al-and Fe-nitrilotriacetate. In this study, we examined the effect of non-Fe metals on IRP using gel shift and the enzyme assays. IRE was transcriptionally synthesized in vitro and IRP purified from the beef liver. Non-Fe metals including mercury, cadmium, copper, manganese and nickel decreased the binding activities of IRP to IRE with an increase in the aconitase activity in a dose-dependent manner. These data suggest that non-Fe metals bind IRP in 3Fe-4S state to influence its function.

View full abstract