Kosei Yonemitsu

Inhibitory activity of epigallocatechin gallate (EGCg) in paraquat-induced microsomal lipid peroxidation - A mechanism of protective effects of EGCg against paraquat toxicity

Recently we have reported that epigallocatechin gallate (EGCg), a major component of Japanese green tea, significantly increased the survival rate of paraquat (Pq) poisoned mice. This paper describes two biochemical activities of EGCg, which relate to its protective effects against Pq toxicity. EGCg inhibited Pq-induced microsomal malondialdehyde (MDA) productions in rat liver microsome system containing 40 microM FeSO(4). Forty micromolar EGCg inhibited MDA production significantly. EGCg may inhibit the Pq-induced MDA production by at least two mechanisms. One may be iron-chelating activity as the inhibition disappeared when excess amounts of FeSO(4) were added to the reaction mixture, which indicated that EGCg reduced iron driven lipid peroxidation by pulling out available irons in the reaction mixture. The other is radical scavenging activity. EGCg scavenged DMPO-OOH spin adducts generated by the microsome-Pq system. The dose response curve of EGCg was similar to that obtained by ascorbic acid which is a typical water-soluble radical scavenger. Although ascorbic acid had a potential activity of scavenging superoxide radicals, it can not be recommended to use for the treatment of Pq poisoning, because ascorbic acid acts as a pro-oxidant in the presence of free transition metal ions by accelerating the Fenton reaction (Fe(2+)+H(2)O(2)-->Fe(3+)+OH(-)+OH*), which is responsible for lipid peroxidation. On the contrary, EGCg inhibited iron-driven lipid peroxidation presumably not only by chelating to Fe ions but also by scavenging superoxide radicals, which are responsible for the reduction of ferric (Fe(3+)) to ferrous (Fe(2+)) that catalyzes the Fenton reaction. Chelating and radical scavenging activity of EGCg can be expected simultaneously in the occurrence of Pq toxicity, which may explain the protective effects of EGCg against Pq toxicity.

Calmodulin-like activity in the soluble fraction of Escherichia coli

Abstract A heat-stable factor with properties similar to those of calmodulin was found in the fraction containing Ca 2+ -dependent cyclic AMP phosphodiesterase of Escherichia coli . The factor activated such enzymes as cyclic nucleotide phosphodiesterase of bovine brain, (Ca 2+ ,Mg 2+ )ATPase of human erythrocyte menbrane and myosin light chain kinase of rabbit myometrium in a Ca 2+ -dependent fashion with an apparent K a of 5 × 10 −5 M . The factor and brain calmodulin had no effect on the phosphodiesterase of E. coli . It may be concluded that calmodulin or a calmodulin-like protein occurs in prokaryotes.

Postmortem changes in blood tranylcypromine concentration: Competing redistribution and degradation effects

Site and temporal changes in tranylcypromine (TCP) and lithium concentrations in blood were studied in a human poisoning case. Blood samples from peripheral vessels and six central vessels were obtained at 0, 6, 24, 48 and 72 h after starting the autopsy. Nine tissue samples were obtained on completion. TCP showed preferential concentration in liver (2.21 micrograms/g) and brainstem (2.46 micrograms/g). There was a moderate post mortem redistribution phenomenon with TCP concentrations lowest in peripheral blood (0.17 micrograms/ml) at 0 h and highest in central vessels at 24 h (0.52 micrograms/ml). At 72 h blood TCP concentrations fell below those at 0 time but the samples showed marked putrefactive changes. Control blood samples spiked with TCP and incubated for 48 h at 37 degrees C showed a 58% fall in drug concentration. By contrast with TCP, lithium, which has a small Vd (0.8 l/kg) and is chemically stable, did not show this pattern of change in blood concentration. The site and temporal differences in TCP concentration in blood can be explained by the competing effects of post mortem redistribution and drug degradation. Redistribution is an early post mortem phenomenon characterised by diffusion, along a concentration gradient, from drug reservoirs in solid organs into adjacent blood vessels. Drug degradation is a later phenomenon associated with putrefactive change.

1. Accidental decapitation: An unusual injury to a passenger in a vehicle

A case of decapitation of a vehicle passenger in an accident on a highway is reported. Evaluation of roadside evidence and the deceaseds injuries revealed that the victim was partially ejected from a broken passenger-side window as the vehicle spun out of control, decapitation being due to the impact of his head against a barrier stanchion on the shoulder of the road. An unfastened seat-belt, high-speed driving and the construction of the road barrier were contributory factors.

Pharmacokinetic profile of paraquat following intravenous administration to the rabbit

Pharmacokinetic studies of paraquat in rabbits were performed using [methyl-14C]-paraquat. Plasma concentration of paraquat following i.v. administration to the rabbit was fitted to a 3-exponential function of pharmacokinetic analysis. Distribution and elimination were discussed on the basis of the 3-compartment open model system, which has a central and two peripheral compartments. Computer simulations of paraquat levels in each compartment indicated that the slow-uptake peripheral compartment contained a greater amount of paraquat than the central or the fast-uptake peripheral compartment. On the basis of the present results of the computer simulations in company with tissue distributions of paraquat reported by the other investigators, it is likely that the slow-uptake peripheral compartment contains the lung. In cases of paraquat-induced renal failures, the paraquat levels of the slow-uptake peripheral compartment were remarkably higher than in cases of normal renal functions. Histology of the rabbit tissues 7 days after i.v. administration of paraquat revealed that marked changes were observed only in the kidney, suggesting some renal failures induced by paraquat. In spite of the high concentration of paraquat, which was presumed with the computer simulations in this study, the rabbit lung showed a remarkable resistance to paraquat toxicity. The histology studies suggested the complexities of paraquat toxicity to the rabbit. The lung toxicity in the rabbit would be caused by not only the paraquat concentration in the lung but also some biochemical parameters in the tissue related to the mechanisms of paraquat toxicity.

Immunohistochemical demonstration of the distribution of chloroquine (CQ) and its metabolites in CQ-poisoned mice

Chloroquine (CQ) distribution in tissues of acutely poisoned mice was demonstrated by immunohistochemistry using anti-CQ polyclonal antibodies (PAC). PAC recognized 4-amino-7-chloro-quinoline structure and sufficiently reacted with CQ and CQ’s metabolite bisdesethyl-chloroquine. In the brain, CQ and its metabolites (CQs) localized in the region of the choroids plexus, indicating an important role in the blood–cerebrospinal barrier system. In the heart, most regions showed diffused positive staining, and relatively strong reaction was observed in Purkinje cells, indicating an important role in acute CQ toxicity. In the lungs, CQs were observed in the bronchial epithelium, type II pneumocytes, and on the surface of alveolar walls. It was suggested that CQs were excreted to the alveolar wall with surfactant phospholipids, which are produced by type II pneumocytes. In the liver, CQs were concentrated in the centrolobular area rather than in the periportal area, in agreement with CQ’s metabolic pathway. In the kidneys, tubular cells were strongly stained compared to glomerular capsules, and the distal part of renal tubules was better stained than the proximal tubules. These findings suggested that CQs were predominantly excreted or reabsorbed through the distal tubules and the collecting duct. Distribution of CQs in tissues presented here were mostly consistent with the physico-chemical properties of CQ and its metabolites. However, the elucidation of CQs’ localization in Purkinje cells remains open. Further experimental studies at the level of microorganella will be needed to clarify the present result.

Quantitative evaluation of volatile hydrocarbons in post-mortem blood in forensic autopsy cases of fire-related deaths

Volatile hydrocarbons in post-mortem blood from victims of fires were analyzed quantitatively by headspace gas chromatography mass spectrometry. The benzene and styrene concentrations in the blood were positively correlated with the carboxyhemoglobin (CO-Hb) concentration, which is evidence that the deceased inhaled the hydrocarbons and carbon monoxide simultaneously. By contrast, the concentrations of toluene and CO-Hb in the blood were not significantly correlated. This lack of correlation could be explained by two different sources of toluene, with low blood concentrations of toluene arising when the deceased inhaled smoke and high blood concentrations of toluene arising when the deceased inhaled petroleum vapor or other unknown vapors. The quantity of soot deposited in the respiratory tract was classified into four grades (-, 1+, 2+, 3+). The mean CO-Hb concentration in the 1+ soot group was significantly lower than those in the 2+ (p<0.05) and 3+ (p<0.01) soot groups. The blood CO-Hb concentrations in the 1+ soot group were all below 30%. Those indicated that the deceased aspirated smoke that contained both soot and carbon monoxide. The wide variation in CO-Hb concentrations for each soot classification could be caused by the different types of smoke produced by different materials. For example, petroleum combustion with a limited supply of oxygen, like in a compartment fire, may produce a large volume of dense black smoke that contains a large quantity of soot. Soot deposits in the airways and the blood CO-Hb concentration are basic and essential autopsy findings that are used to investigate fire-related deaths. The quantitative GC-MS analysis of blood volatile hydrocarbons can provide additional useful information on the cause of the fire and the circumstances surrounding the death. In combination, these three findings are useful for the reconstruction of cases.

Vertebral arterial injury due to fatal dog bites

Dog bite-related injuries and fatalities are major public health problem worldwide. The authors present a case of a Japanese Tosa-dog bite-related fatality in an old woman who died from a vertebral arterial laceration with the C5 vertebral fracture. This was an uncommon type of injury that dog bites injured the vertebral artery only without damage to carotid artery. The identity of the Tosa-dog as an offending dog in this case was unsuccessful by a DNA analysis. Then the detection of the offending dog was made by comparisons of the dental casts of the dog with the victims wounds. This case report describes making dental cast of the dog, and statistical data on dog-bite incidents in Japan.

Neuropathological diagnosis of Alzheimer's disease in forensic autopsy of elderly persons with fatal accident

Cognitive dysfunction in Alzheimers disease may lead to accidental deaths in the elderly. Neuropathological diagnosis of the disease is, therefore, an important issue in forensic autopsy to determine the causal relation to accidents. To evaluate the suitability of the current histopathological diagnostic criteria for Alzheimers disease by Khachaturian and Mirra et al. in elderly persons dying from accidents and coming for forensic autopsy, we studied the brains of nine demented and 12 non-demented persons by silver stain and immunohistochemistry. When the density of senile plaque was applied to the criteria, only four out of nine demented persons met the criteria for definite Alzheimers disease. The demented persons had significantly higher density of diffuse plaque and higher frequencies of amyloid angiopathy, neurofibrillary tangle and neuropil thread than the non-demented persons. These results indicated that the current diagnostic criteria do not always diagnose Alzheimers disease in forensic autopsy of elderly persons with fatal accident. The presence of abundant diffuse plaque, neurofibrillary tangle, amyloid angiopathy and neuropil thread may help to diagnose Alzheimers disease in forensic autopsy.

Allergic contact dermatitis from unsaturated polyester resin consisting of maleic anhydride, phthalic anhydride, ethylene glycol and dicyclopentadiene

A 58-year-old man who had worked in a fibreglass-reinforced plastics (FRP) factory for over 30 years, reported that dermatitis first appeared on his hands 2 months after he started working in the factory and that the condition has recurred since, especially in summer. A first patch test session included 2 kinds of unsaturated polyester resins UP(a) and UP(b) (1%, 5%, 10% pet.) obtained from the factory, and their bases (1, 5% pet.) provided by a manufacturer, methyl ethyl ketone peroxide (0.5% pet.) and dimethyl aniline (10% o.o), all of which were prepared in the laboratory, together with a plastics (Trolab) and a Japanese standard series. The Finn ChamberA technique with a occlusion time of 2 days was used for patch tests, which were read 1 day after removal according to ICDRG standard. The results showed positive results (π) to cobalt, UP(a) (1%, 5%, 10%) and UP(a) base (1%, 5%). UP(a) base comprises 4 chemicals: maleic anhydride (MAn), phthalic anhydride (PAn), ethylene glycol and dicyclopentadiene (DCPD) (Fig. 1, Table 1). Purified UP(a) was fractionated by thin-layer chromatography (TLC) and the fractions were scraped and extracted from the TLC plate and patch tested (1). The fraction