Cannabis, alcohol and other drug findings in fatally injured drivers in Ontario.

OBJECTIVE: The purpose of this study was to determine the prevalence of cannabis, alcohol and other drug use in drivers of motor vehicles who died in crashes in the Canadian province of Ontario from January 2016 through December 2018 along with the characteristics of these drivers and some of the circumstances of the crash in which they were involved. METHODS: Toxicological tests were performed on blood samples obtained from 921 driver fatalities for whom postmortem blood samples were submitted to the Center of Forensic Sciences for analysis. The results were coded into a database along with basic demographic and crash characteristics and examined for prominent characteristics and patterns. RESULTS: Overall, among the 921 cases examined, 495 (53.7%) tested positive for alcohol, cannabis (tetrahydrocannabinol or THC), or another psychoactive drug. The number of cases that tested positive for THC (251) exceeded the number of cases that tested positive for alcohol (241) as well as the number that tested positive for a drug other than THC (235). In 38% of positive cases, more than one substance was detected. Alcohol and THC were most commonly detected among males; females most frequently tested positive for a drug other than THC, notably medications with depressant effects. Alcohol-involved driver fatalities were most common on weekends and most likely involved single vehicle crashes. Driver fatalities that tested positive for THC or another drug were more evenly distributed throughout the week and were more likely to have been in multi-vehicle crashes. CONCLUSIONS: The present study highlights the use of cannabis and other drugs by drivers. The patterns of crashes and the characteristics of drivers involved indicate that the characteristics of driver fatalities involving cannabis and/or other drug use differ from those of alcohol and require new, innovative approaches targeting high-risk times, groups and behaviors. Continued monitoring of the toxicological findings from blood samples obtained from drivers killed in motor vehicle crashes will be a key element in efforts to reduce the impact of drug use by drivers on road safety.

Structure of bacterial glutathione-S-transferase maleyl pyruvate isomerase and implications for mechanism of isomerisation.

Maleyl pyruvate isomerase (MPI) is a bacterial glutathione S-transferase (GST) from the pathway for degradation of naphthalene via gentisate that enables the bacterium Ralstonia to use polyaromatic hydrocarbons as a sole carbon source. Genome sequencing projects have revealed the presence of large numbers of GSTs in bacterial genomes, often located within gene clusters encoding the degradation of different aromatic compounds. This structure is therefore an example of this under-represented class of enzymes. Unlike many glutathione transferases, the reaction catalysed by MPI is an isomerisation of an aromatic ring breakdown product, and glutathione is a true cofactor rather than a substrate in the reaction. We have solved the structure of the enzyme in complex with dicarboxyethyl glutathione, an analogue of a proposed reaction intermediate, at a resolution of 1.3 A. The structure provides direct evidence that the glutathione thiolate attacks the substrate in the C2 position, with the terminal carboxylate buried at the base of the active site cleft. Our structures suggest that the C1-C2 bond remains fixed so when rotation occurs around the C2-C3 bond the atoms from C4 onwards actually move. We identified a conserved arginine that is likely to stabilize the enolate form of the substrate during the isomerisation. Arginines at either side of the active site cleft can interact with the end of the substrate/product and preferentially stabilise the product. MPI has significant sequence similarity to maleylacetoacetate isomerase (MAAI), which performs an analogous reaction in the catabolism of phenylalanine and tyrosine. The proposed mechanism therefore has relevance to the MAAIs. Significantly, whilst the overall sequence identity is 40% only one of the five residues from the Zeta motif in the active site is conserved. We re-examined the roles of the residues in the active site of both enzymes and the Zeta motif itself.