Is it worth carrying out determination of N-butane in postmortem samples? A case report and a comprehensive review of the literature.

The aim of this article is to illustrate the importance of N-butane determination in postmortem samples through a case report and to propose actions and precautions to be taken into consideration when butane is suspected to be involved in cases of death. The case concerns a 15-year-old boy found dead after sniffing a cigarette lighter refill. Toxicological investigation revealed the presence of butane in the heart and femoral blood (1280 and 1170 µg/L, respectively), in the gastric contents (326 µg/L), and in the liver (1010 µg/kg) and lung tissues (210 µg/kg). Propane was present only in the blood samples at concentrations tenfolds lower.Butane can be involved in three kinds of fatalities: deliberate inhalations including volatile substance abuse (VSA), involuntary exposure, and homicides. A fatal outcome of butane inhalation can be caused by asphyxia and/or cardiac arrhythmia. In the context where butane exposure is evidenced by non-toxicological investigations, the usefulness of the determination of butane in postmortem samples is often questionable. However, it is admitted that butane-related deaths are generally underreported. Several difficulties including sample handling and storage, substantial variation in tissue concentrations, and lack of a lethal threshold make the interpretation of butane results challenging. In our opinion, systematic toxicological methods should be developed in order to analyze butane, at least when it concerns a typical VSA victim, even when butane is not actually suspected to be the cause of death.

Cytochrome P450 2E1 is responsible for the initiation of 1,2-dichloropropane-induced liver damage.

1,2-Dichloropropane (1,2-DCP), a solvent, which is the main component of the cleaner used in the offset printing companies in Japan, is suspected to be the causative agent of bile duct cancer, which has been recently reported at high incidence in those offset printing workplaces. While there are some reports about the acute toxicity of 1,2-DCP, no information about its metabolism related to toxicity in animals is available. As part of our efforts toward clarifying the role of 1,2-DCP in the development of cancer, we studied the metabolic pathways and the hepatotoxic effect of 1,2-DCP in mice with or without cytochrome P450 2E1 (CYP2E1) activity. In an in vitro reaction system containing liver homogenate, 1,2-DCP was only metabolized by liver tissue of wild-type mice but not by that of cyp2e1-null mice. Furthermore, the kinetics of the solvent in mice revealed a great difference between the two genotypes; 1,2-DCP administration resulted in dose-dependent hepatic damage, as shown biochemically and pathologically, but this effect was only observed in wild-type mice. The nuclear factor κB p52 pathway was involved in the liver response to 1,2-DCP. Our results clearly indicate that the oxidative metabolism of 1,2-DCP in mice is exclusively catalyzed by CYP2E1, and this step is indispensable for the manifestation of the hepatotoxic effect of the solvent.

Time course of blood parameters in printing workers with cholangiocarcinoma.

OBJECTIVES: We previously reported a cluster of cholangiocarcinoma patients among proof-printing workers who were exposed to 1,2-DCP for a long term. The present study was conducted to evaluate blood parameters in these proof-printing workers during and after exposure. METHODS: Health examination records during employment and after retirement were obtained for ten cholangiocarcinoma patients to analyze their blood parameters. The patients and/or their relatives were also interviewed about lifestyle and occupational history. RESULTS: All study patients were exposed to 1,2-DCP for 6-17 years. Red blood cells, hemoglobin, hematocrit, total cholesterol, triglycerides, and fasting plasma glucose were within the standard ranges for almost all patients, but the γ-glutamyl transpeptidase (γ-GTP) levels exceeded the standard range during 1,2-DCP exposure for six patients. Two of the six patients were diagnosed with cholangiocarcinoma during 1,2-DCP exposure, and the other four patients were diagnosed 1-9 years after termination of exposure. The remaining four patients had γ-GTP levels within the standard range during 1,2-DCP exposure, but had increased γ-GTP levels thereafter, and were diagnosed with cholangiocarcinoma 4-10 years after termination of exposure. Aspartate aminotransferase and alanine aminotransferase levels started to increase following the increase in γ-GTP levels. CONCLUSIONS: Workers exposed to 1,2-DCP should be provided with periodic health examinations during and after exposure. In the examination, even small increases in γ-GTP levels should be considered a signal of early development of cholangiocarcinoma.

Dysregulation of PRMT1 and PRMT6, Type I arginine methyltransferases, is involved in various types of human cancers.

Protein arginine methylation is a novel post-translational modification regulating a diversity of cellular processes, including histone functions, but the roles of protein arginine methyltransferases (PRMTs) in human cancer are not well investigated. To address this issue, we first examined expression levels of genes belonging to the PRMT family and found significantly higher expression of PRMT1 and PRMT6, both of which are Type I PRMTs, in cancer cells of various tissues than in non-neoplastic cells. Abrogation of the expression of these genes with specific siRNAs significantly suppressed growth of bladder and lung cancer cells. Expression profile analysis using the cells transfected with the siRNAs indicated that PRMT1 and PRMT6 interplay in multiple pathways, supporting regulatory roles in the cell cycle, RNA processing and also DNA replication that are fundamentally important for cancer cell proliferation. Furthermore, we demonstrated that serum asymmetric dimethylarginine (ADMA) levels of a number of cancer cases are significantly higher than those of nontumor control cases. In summary, our results suggest that dysregulation of PRMT1 and PRMT6 can be involved in human carcinogenesis and that these Type I arginine methyltransferases are good therapeutic targets for various types of cancer.

The forensic investigation of propane gas asphyxiation.

Two unusual suicides of a 19-year-old white man and a 47-year-old white man, involving propane inhalation and plastic bag suffocation, are described. The special characteristics of propane gas as an asphyxiant agent are discussed, as well as its effect on the human body. The discussion emphasizes the postmortem examination and the collection of samples for toxicologic analysis.

Liquefied petroleum gas (LPG) poisoning: report of two cases and review of the literature.

Two autopsy cases of men who died while connecting a liquefied petroleum gas (LPG) pipe are reported. Their blood concentrations of propane (the main content of LPG) were 0.12 and 3.40 mg/100 g, respectively. The cause of death after exposure of LPG has generally been considered to be asphyxia from hypoxia. The large differences in the blood propane levels found here and reported in the literature, however, suggest that direct toxic effects of propane poisoning may be the cause of death in some cases. Propane concentrations and the cause of death are reviewed and discussed.

Toxicological investigation of liquid petroleum gas explosion: human model for propane/ethyl mercaptan exposures.

Four individuals died as the result of a propane explosion. As with many propane explosions, the question was raised as to the adequacy of the product's odorization after the autopsy studies had been conducted. In most cases, this question leads to litigation. Ethyl mercaptan is a widely used odorant for propane and was used in this instance. Three of the four victims had blood available at autopsy for study. Quantitative analyses of the victims' blood, obtained during autopsy, were performed using gas chromatography/mass spectrometry, without subjecting the samples to hydrolysis. These analyses determined the relative amounts of propane and ethyl mercaptan in the blood to be 90, 63, and 175 mL/m3 headspace, and 0.36, 0.34, and 0.77 microgram/L blood, respectively. Since mercaptans have been reported in human blood as products of metabolism, modeling studies were conducted to establish the validity of the autopsy data and to develop an autopsy toxicology protocol for investigating explosion deaths. When subjects were not exposed to an atmosphere containing ethyl mercaptan, dimethylsulfide was the only mercaptan detectable in their blood without severe hydrolysis prior to analysis. Metabolic ethyl mercaptan is sufficiently bound to be undetectable by the methods used without hydrolysis. Human subjects were exposed to a flammable mixture of air and propane odorized with ethyl mercaptan. The analyses of the blood from these subjects produced results which were comparable with those for the explosion victims, establishing that the question of odorant adequacy can be addressed at the autopsy of propane explosion victims. It is extremely important that the pathologist and toxicologist investigating gas explosion deaths recognize the valuable evidence existing in the victim's blood.

1,2-Dichloropropane hepatotoxicity in rats after inhalation exposure.

The hepatic effects of 1,2-dichloropropane (DCP) were investigated in male Wistar rats exposed to 15, 50, 100, 250, 450, 1000, 1300, 1800 or 4900 mg DCP m-3. At the end of a 4-h period of exposure, average blood DCP levels were 0.025 and 5.38 micrograms ml-1 in animals treated with 15 and 1300 mg m-3, respectively. Blood DCP concentrations were correlated with the air DCP concentrations in the inhalation chamber. At DCP concentrations of 100 mg m-3 or higher, the liver non-protein thiol (NPT) content was significantly reduced. Assays performed 20 h after 4-h DCP exposure showed that exposure to 100-1000 mg DCP m-3 had no effect on hepatic NPT levels. The NPT content increased only in the liver of rats exposed to higher (1300-4900 mg m-3) DCP concentrations. Treatment with DCP did not cause hepatic lipid peroxidation and did not modify total protein content. The observed changes in liver cell thiol homeostasis are likely to reflect the action of reactive intermediates formed during DCP metabolism. These changes can occur in rats following exposure to considerably low levels of DCP vapour.

Species differences in kidney necrosis and DNA damage, distribution and glutathione-dependent metabolism of 1,2-dibromo-3-chloropropane (DBCP).

Species differences and mechanisms of 1,2-dibromo-3-chloropropane (DBCP) nephrotoxicity were investigated by studying DBCP renal necrosis and DNA damage, distribution and glutathione-dependent metabolism in rats, mice, hamsters and guinea pigs. Extensive renal tubular necrosis was observed in rats 48 hr after a single intraperitoneal administration (21-170 mumol/kg) of DBCP. Significantly less necrosis was found in mice and guinea pigs, whereas no renal damage was evident (less than 680 mumol/kg) in hamsters. The activation of DBCP to DNA damaging intermediates in vivo, as measured by alkaline elution of DNA isolated from kidney nuclei 60 min. after intraperitoneal injection of DBCP, was compared in all four species. Distinct DNA damage was detected in rats, mice and hamsters as early as 10 min. after administration of DBCP and within 30 min. in guinea pigs. Rats and guinea pigs showed similar sensitivity towards DBCP-induced DNA damage (extensive DNA damage greater than 21 mumol/kg DBCP), whereas in mice and hamsters a 10-50 times higher DBCP dose was needed to cause a similar degree of DNA damage. Renal DBCP concentrations at various time-points (20 min., 1, 3 and 8 hr) after intraperitoneal administration (85 mumol/kg) revealed that the initial (20 min.) DBCP concentration was substantially higher in rats and guinea pigs compared to the other two species. Furthermore, kidney elimination of DBCP occurred at a significantly lower rate in rats than in mice, hamsters and guinea pigs.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal necrosis and DNA damage caused by selectively deuterated and methylated analogs of 1,2-dibromo-3-chloropropane in the rat.

Selectively deuterated and methylated analogs of the nematocide 1,2-dibromo-3-chloropropane (DBCP) were compared to DBCP in causing acute renal damage in rats. All of the six deuterated analogs tested at 340 mumol/kg, including the perdeutero compound, failed to significantly alter the kidney necrosis observed at 48 hr compared to DBCP. Furthermore, when the perdeutero analog was administered at several doses (42.5, 85, 170, and 340 mumol/kg), it caused kidney damage that was not significantly different than that caused by an equivalent molar dose of nondeuterated DBCP. Of the five methylated analogs tested at 170 and 340 mumol/kg, only C3-methyl-DBCP and 1,2-dibromo-4-chlorobutane caused nephrotoxicity. The C2-methyl-, C1-dimethyl-, and C2-methyl-DBCP analogs failed to cause renal necrosis determined 48 hr after dosing. In distribution studies DBCP, perdeutero-DBCP, and all the methylated analogs were found to concentrate in the kidney approximately 25 times relative to plasma 1 hr after administration. DBCP at doses of 4.3 mumol/kg and higher caused DNA damage in the kidney as early as 10 min after administration, as measured by alkaline elution of DNA from isolated kidney nuclear preparations. Perdeuteration did not decrease the DNA damaging effect of DBCP. The ability of the methylated DBCP analogs to induce renal DNA damage correlated with their necrogenic potential. Experiments using pretreatments that are known to decrease the nephrotoxicity caused by glutathione and cysteine conjugates of several halogenated alkenes were conducted to examine the effect of these pretreatments on DBCP-induced nephrotoxicity. Probenecid, L-(alpha S,5S)-alpha-amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid (AT-125) and aminooxyacetic acid did not significantly alter renal necrosis or DNA damage induced by DBCP. Based on the absence of any significant isotope effects with the predeutero-DBCP analog, it appears that breaking of a carbon-hydrogen bond is not the rate-limiting step in DBCP-induced nephrotoxicity. Studies with the methylated DBCP analogs indicate that a vicinal dibromo ethyl group must minimally be present for nephrotoxic potential. Furthermore, it seems unlikely that metabolism by renal cysteine conjugate beta-lyase is rate-limiting for DBCP nephrotoxicity.

Fulminant hepatic failure after occupational exposure to 2-nitropropane.

Two construction workers became ill after applying an epoxy resin coating containing 2-nitropropane in the confined space of an underground concrete vault. One man died 10 days later from fulminant hepatic failure. The second man recovered but has had persistently elevated serum aminotransferase activity. The serum concentration of 2-nitropropane on admission of the man who died was 13 mg/L, and was 8.5 mg/L in his coworker. The acute toxicity of 2-nitropropane has not been widely appreciated despite previous reports of death due to hepatic failure after exposure to the compound in confined spaces. These cases show the importance of effective education and protective work practices.

Quantitative determination of 1,2-dibromo-3-chloropropane in whole rat blood and drinking water by gas chromatography.

1,2-Dibromo-3-chloropropane (DBCP) in an amber-colored liquid that has been used as a soil fumigant for nematodes since 1957 in agricultural cropland. Formulations containing DBCP have been primarily sold under the trademarks Fumazone (Dow Chemical, Midland, MI, U.S.A.) and Nemagon (Shell, THe Hague, The Netherlands). Recent reports have associated exposure to DBCP with disruption of spermatogenesis and azoospermia or oligospermia in male workers. Tests on laboratory animals have indicated that DBCP has an adverse effect on spermatogenesis and leads to testicular atrophy. In support of DBCP studies in animals, an analytical method was developed to determine low-level concentrations of DBCP in whole blood. Previous analytical methods for DBCP in blood required extensive sample preparation and steam distillation which limits the number of analysis per time period. This paper describes a simple gas chromatographic-electron-capture detection (GC-ECD) method that is both specific and sensitive to DBCP blood levels at concentrations as low as 2.28 x 10(-1) ng/ml DBCP. In addition, a quantitative analytical method was developed to measure levels of DBCP in drinking water which parallels the method in blood.