Use of the CYP2E1 genotype and phenotype for the biological monitoring of occupational exposure to styrene.

The CYP2E1 has been identified as the main cytochrome P450 isoform involved in human styrene metabolism. CYP2E1 presents polymorphism in humans and the different genotypes may, at least partly, be related to the different levels of individual expression of enzyme activity. We studied whether the genetic polymorphisms and phenotype of CYP2E1 modulate the level of urinary styrene metabolites and if they can be used for assessing risks of occupational exposure to styrene. A population of 49 male workers exposed to styrene (average level 362.7mg/m(3)) and a control group were selected. Samples of urine, blood and buccal swab were taken to determine the urinary biological indicators (phenylglyoxylic acid and mandelic acid), to quantify mRNA of CYP2E1 in blood using RT-PCR and to analyse different polymorphisms of enzyme CYP2E1 from buccal swab. We found decreased expression of mRNA of the enzyme, as well as decreased excretion of the styrene metabolites in individuals carrying the CYP2E1*5B heterozygote allele (cl/c2) with respect to the wild-type homozygote (c1/c1), which indicates a reduction in the inducibility of the enzyme in the presence of this polymorphism. The results show that the combined effect of both the CYP2E1 phenotype, measured by the expression of the specific mRNA in blood samples, and the CYP2E1*5B allele genotype, may explain the variability of urinary excretion of the styrene metabolites.

Application of biochemical and X-ray diffraction analyses to establish the postmortem interval.

The determination of the date of death from bone remains is of scientific interest but also has important legal implications. The establishment of the postmortem interval (PMI) is a very complex problem because of the great number of intrinsic factors that may alter the normal course of postmortem change, such as the age, sex, constitution and previous physiological and pathological states of the subject, and external factors. In order to evaluate the utility of X-ray diffraction and the measurement of some components in dating bone remains, a total of 69 long bones from 69 different cadavers (41 males, 28 females) with a mean age of 68 years (S.D.=17.6, range 12-97) were used. The bones were removed from cement tombs of Murcia Cemetery, where they had lain for documented times of between 7 and 54 years (S.D.=11.6, mean time 17.6 years). We have studied potassium, sulphur, nitrogen, urea, total protein, phosphorus, and some X-ray diffraction (XRD) parameters related to the degree of crystallinity of the mineral component in medullar and cortical bone zones to establish which of the two provides the most useful information for calculating the PMI. In the overall analysis of our data, we believe that the use of both XRD and biochemical analyses (especially of urea, potassium and sulphur) particularly in the cortical zone of the bone could be an alternative method for dating osseous remains.

Activation of soluble guanylate cyclase by nitric oxide is increased in lymphocytes from both rats chronically exposed to 2,5-hexanedione and workers chronically exposed to n-hexane.

Although occupational exposure to n-hexane induces neurotoxic effects in the central and peripheral nervous systems, the mechanisms of its neurotoxicity remain unclear. n-Hexane is metabolized to 2,5-hexanedione (2,5-HD), which is the neurotoxic agent and the indicator chosen for the biological monitoring of exposed workers. It has been previously reported that chronic exposure to 2,5-HD impairs the glutamate-nitric oxide-cyclic GMP pathway at the level of activation of soluble guanylate cyclase (sGC) enzyme by nitric oxide (NO), both in cultured neurons and in the cerebellum of rats in vivo. The aim of this study was to assess whether the activation of sGC by NO is also altered in lymphocytes from rats treated with 2,5-HD and/or workers chronically exposed to n-hexane. Lymphocytes were isolated from male Wistar rats treated with 2,5-HD in drinking water, and from blood samples from shoe-factory workers environmentally and chronically exposed to n-hexane. Urine samples were also collected from workers at the end of the shift in order to measure the urinary levels of 2,5-HD. Activation of sGC by NO was significantly higher (p<0.05) in lymphocytes from rats treated with 2,5-HD than in control rats. In isolated lymphocytes from exposed workers the activation of sGC by NO also increases (p<0.05) in contrast to the controls. The results presented here indicate that the activation of lymphocytes could be an indicator of the toxicity produced by being exposed to n-hexane, since the effects observed in workers chronically exposed to n-hexane are similar to those found in rats chronically treated with 2,5-HD in drinking water.