The 6beta-hydroxycortisol/cortisol ratio was measured in 52 children aging 1.1-14.0 years. The maximum increment in this ratio occurred in the age interval of 1.1-2.0 years. During this period, the regression coefficients in the linear (r=0.57; p=0.044) and nonlinear logarithmic models (r=0.56; p=0.049) were similar. At the age of 10-14 years, the examined ratio attained 19.17+/-17.79.
The effect of age and gender on the in vitro biotransformation of 2-methylpropene, an alkene metabolized to 2-methyl-1,2-epoxypropane, was studied. The epoxide concentration and the epoxide metabolizing enzymatic activities were investigated in male and female Brown Norway rats of different ages. Liver tissue of senescent rats was exposed to smaller 2-methyl-1,2-epoxypropane concentrations than that of young animals, although changes during ageing were rather modest. With advancing age a feminization of male glutathione S-transferase and cytosolic epoxide hydrolase activities was found, as well as a significant decline of the female microsomal epoxide hydrolase activity and an increase of the cytochrome P-450 content in the oldest female rats.
Four seabird species and their prey (zooplankton or fish) were collected in the Barents Sea to determine how dietary exposure, cytochrome P450 (CYP) enzyme activities and sex influenced their hepatic PCB concentrations and accumulation patterns. Five males and five females from each seabird species (little auk (Alle alle), Brunnich's guillemot (Uria lomvia), black guillemot (Cepphus grylle) and black-legged kittiwake (Rissa tridactyla)) were analysed. PCB concentrations could not be explained directly by carbon source (delta13C) or trophic position (delta15N), but by a combination of dietary parameters (delta13C, delta15N, migratory pattern, age) and contaminant metabolism. Contrary to previous studies, the PCB pattern differed among seabirds, with a higher proportion of persistent congeners (% of PCB-153, RPCB-153) in black-legged kittiwake than in auks. The PCB pattern also differed among auks, with little auk as the most efficient biotransformer (highest RPCB-153 values of persistent congeners). Based on high RPCB-153 values, Brunnich's guillemot poorly metabolised ortho-meta-unsubstituted congeners, whereas black guillemot poorly metabolised meta-para unsubstituted congeners. Species-specific differences in PCB biotransformation were confirmed by metabolic indices, where PCB patterns in seabirds were adjusted for PCB pattern in prey. The relative contribution of ortho-meta-unsubstituted congeners to SigmaPCBs decreased with increasing EROD activity. There were no differences in PCB concentrations, PCB patterns or cytochrome P450 enzyme activities between males and females. CYP P450 activities (CYP1A- and CYP2B/3A-like: EROD and testosterone 6beta-hydroxylation, respectively) were low and did not correlate with concentrations of non- or mono-ortho Cl-substituted PCBs (NO- and MO-PCBs), or with total toxic equivalent concentrations (TEQs) for dioxin-like effects of NO- and MO-PCBs.
Congener specific PCB and toxaphene (polychlorinated camphene, PCC) analyses were performed in seal blubber, collected in Svalbard, Norway. The concentration, body burden and metabolic index (PCB congener concentration in seal relative to their prey) were calculated. Multiple regression analyses were carried out to evaluate the influence of age, sex, blubber (as a percentage of total body weight) and cytochrome P450 activities on PCB and PCC levels. Levels of total PCBs found were five times higher than in ringed seals from the Canadian Arctic, corresponding with the relatively high contaminant levels in the European Arctic. The dominant PCB congeners (> 70% of the total PCBs measured) were 153, 138, 99, 180 and 101. The observed PCB and PCC accumulation patterns were very similar to patterns in seals from other studies, suggesting a large resemblance in contaminant metabolism. A decrease in the relative abundance of the lower chlorinated PCBs, was associated with higher concentrations of PCB 153. Since there was no indication for selective PCB excretion by lactating females, this suggests metabolism of these PCBs in ringed seals due to xenobiotic metabolising enzymes. The metabolic index confirmed the model of persistency of the different PCBs except for congener 128 and 138. These congeners, considered persistent in seals, could to some extent be metabolised in ringed seals. However, co-elution of PCB 138 with PCB 163 and of PCB 128 with TOX 50 possibly has resulted in an underestimation of the metabolic index for these congeners. Multiple regression analyses revealed a significant positive effect of age and a negative effect of the blubber content on the PCB concentrations. Since large fluctuations of body lipids occur between seasons in pinnipeds, PCB measurements should account for the total blubber content to avoid biased results. PCBs with vicinal H-atoms in the o, m or the m, p positions showed in addition a relation with cytochrome P450 enzyme activities. Surprisingly, no effect of sex on the PCB concentrations was observed, probably because female ringed seals, unlike other pinnipeds, continue feeding during lactation. This results in only small amounts of lipid and lipid-associated contaminants being mobilised from the blubber. Consequently, contaminant excretion with the milk will be low. Toxaphene concentrations found were low compared to levels found in the Canadian Arctic. Two congeners, TOX 26 and TOX 50 were predominant (15 and 18%, respectively of total toxaphene). There was no effect of sex, age, total blubber, or cytochrome P450 activities on the toxaphene levels. There was also no correlation between toxaphene and PCB levels, which may indicate differences in exposure and metabolism between these contaminants. Toxaphenes did not bioaccumulate to any substantial extent in ringed seals.
Effects of chemical contaminant exposure may be contributing to the decline of spectacled eiders (Somateria fischeri) nesting in coastal areas of western Alaska. We evaluated chemical exposure and potential effects in 20 male eiders collected near St. Lawrence Island, Alaska. Analytes included metals, trace elements, chlorinated organics, and (137)Cesium ((137)Cs). Effects of contaminant exposure were evaluated using histopathology and biochemical measures of porphyrin profiles, cytochrome P450 activities, and metallothionein (MT) concentrations. Copper, cadmium, and selenium concentrations were elevated in spectacled eiders when compared to literature values for other marine birds. Only a few samples had trace concentrations of chlorinated organic compounds. Muscle (137)Cs levels were all below the average minimum quantifiable concentration of 0.079 Bq/g. No histopathological lesions were associated with elevated contaminant concentrations in liver, kidney, or testes. Protoporphyrin was found in highest concentration in both the liver and kidneys, followed by coproporphyrin and uroporphyrin, respectively. Hepatic uroporphyrin concentrations correlated significantly to hepatic arsenic concentrations. Mean activities of hepatic EROD, MROD, BROD, and PROD were consistent with other avian species. Comparisons of cadmium/MT ratios from this study to published literature ratios in seven marine avian species suggest that, although adult male spectacled eiders have elevated liver concentrations of certain MT-inducing metals, their MT concentrations are not as strongly induced as would be predicted based on literature values. Despite elevated metal concentrations, the apparent good health of the St. Lawrence Island birds suggests that should these contaminants be a factor in population declines, they likely act by decreasing fecundity or survival of young rather than via direct health impacts on adult male spectacled eiders.
Numerous studies demonstrated an importance of cytochrome P-450 epoxygenase pathway of arachidonic acids metabolism for the pathogenesis of essential hypertension (EH). The present study was designed to investigate whether common single-nucleotide polymorphisms (SNP) of CYP2C gene subfamily such as CYP2C8 (rs7909236 and rs1934953), CYP2C9 (rs9332242), and CYP2C19 (rs4244285) are associated with susceptibility to EH in Russian population. A total of 816 unrelated Russian individuals comprising 425 EH patients and 391 normotensive controls were included into the study. Genotyping of SNPs was performed using the MassARRAY 4 system. SNP rs7909236 of CYP2C8 was significantly associated with increased risk of EH (OR adjusted for sex and age was 2.99 95% CI 1.39-6.44, P = 0.005). SNPs rs1934953 CYP2C8 and rs4244285 of CYP2C19 showed association with EH risk but at a borderline statistical significance (P = 0.04). Combination of genotypes CYP2C8 rs7909236 TT and CYP2C19 rs4244285 GG was associated with increased EH risk (OR 3.34 95%CI 1.48-7.51, P = 0.004). Genotype-phenotype correlation analysis showed that the levels of CYP2C8 mRNA were significantly correlated with SNP rs7909236 (P = 0.01). in silico functional prediction analysis revealed the functionality of majority of investigated SNPs. Thus, genes of CYP2C subfamily are important genetic determinants of susceptibility to essential hypertension in Russians.
We examined hepatic cytochrome P450 activity in wild and hand-reared grey partridges (Perdix perdix), capercaillies (Tetrao urogallus) and ring-necked pheasants (Phasianus colchicus), as well as the enzyme activity in a variety of tissues of hand-reared Japanese quails (Coturnix coturnix japonica) and pigeons (Columba livia). Post-mortem decrease in hepatic enzyme activity in the grey partridge was measured. Hepatic 7-ethoxyresorufin-O-deethylase activity was similar in wild and hand-reared grey partridges and pheasants, but the activity was significantly lower in wild than in hand-reared capercaillies, probably resulting from their phenolic-rich diet. In the tissues of both quails and pigeons 7-ethoxycoumarin-O-deethylase exhibited the highest and 7-pentoxyresorufin-O-deethylase the lowest activity. Hepatic enzyme activity was significantly higher than that in other tissues. In the small intestine some activity could be found, reflecting some intestinal detoxication capacity. Enzyme activity decreased by 34-69% during the 30-min sampling period, which confirmed the importance of equalising sampling time to obtain comparable data. Because the hand-reared birds in this study were fed the same commercial diets, we assumed that the enzyme activity values detected reflect species differences without any induction by dietary secondary compounds.
BACKGROUND/AIMS: Interaction between CYP2E1, ethanol metabolites, and enhanced lipid peroxidation is linked to the pathogenesis of alcoholic liver disease. This study was conducted to compare the expression of various cytochrome enzymes and the appearance of aldehyde adducts in humans. METHODS: Acetaldehyde- and lipid peroxidation-derived protein adducts and CYP2A6, 2E1, and 3A4/5 were examined immunohistochemically from liver specimens of 12 alcohol abusers with either mild (n=7) or severe (n=5) liver disease, and from nine non-drinking patients with non-alcoholic steatosis (n=4), or hepatitis (n=5). RESULTS: Ethanol-inducible CYP2E1 was present in all alcoholic livers. While CYP2A6 in zone 3 hepatocytes was also abundant in the alcoholic patients with various degrees of liver disease, CYP3A415 was most prominent in alcoholic cirrhosis. The sites of CYP2E1 and CYP2A6 immunoreactivity co-localized with fatty deposits, and with the sites of acetaldehyde and lipid peroxidation-derived protein adducts. The CYP enzymes were also abundant in the centrilobular hepatocytes of patients with fatty liver due to obesity or diabetes. CONCLUSIONS: Alcohol-induced liver damage is associated with a generalized induction of CYP2A6, CYP2E1 and CYP3A4 and generation of acetaldehyde and lipid peroxidation-derived protein-aldehyde adducts. However, CYP induction also occurred in patients with non-alcoholic steatosis.
Effects of diabetes on hepatic drug metabolism in man has not yet been adequately clarified. Two hundred ninety-eight diabetic patients, classified by type of the disease, age, gender, duration of therapy and liver involvement, were investigated. The antipyrine plasma clearance rate and cytochrome P450 content determinations in liver biopsies of subjects with diagnostic liver biopsy were used as indices of hepatic drug metabolising capacity. Drug metabolism was reduced as a function of age. Antipyrine elimination rate was dependent on the type of diabetes (type 1 versus type 2) and gender. Untreated type 1 patients eliminated antipyrine rapidly and insulin treatment normalised antipyrine elimination (clearance rates 89.5 +/- 20.3 versus 58.8 +/- 17.2 ml/min.; P