The extent of oral fungal flora in 353 students and possible relationships with dental caries.

An epidemiological study was conducted on 353 students to determine the potential relationships between oral saprophytism with Candida albicans and dental status. For each student included, an interview, a dental examination, a mycological investigation and determination of oral pH were conducted. Various factors liable to affect the presence of oral fungus were investigated using the chi(2) test. 58.6% of samples were positive when cultured, with C. albicans in 93.7% of cases. The mean DMF index was 7.6. C. albicans was more frequently isolated in men, smokers, when pH was lower than 7, when dental plaque was abundant and when the time since the teeth had last been brushed was more than 8 h. DMF and F indexes were greater when C. albicans was present but not when it was abundant, while decay was more often present in subjects with abundant C. albicans. Although the specific role of the various factors is difficult to establish, the results suggest that further research to elucidate the possible role of C. albicans in caries aetiology would be valuable.

Evaluation of seven methods of estimating age at death from mature human skeletal remains.

Different approaches to the estimation of age at death in mature human skeletal remains were evaluated utilizing samples from 19 recent French autopsy individuals of known age at death. Methods of estimating age at death from single-rooted teeth, the sternal ends of the fourth ribs, the symphyseal face of the pubis and femoral cortical remodeling were evaluated by two independent observers (three observers for the teeth). Comparison included ages estimated from three more comprehensive approaches utilizing data from the application of two or more of the individual methods. The results indicate that the comprehensive approaches are superior to the individual ones and the success of the latter reflects not only the morphological expression of the aging process, but also the technique complexity and the experience of the investigator. Of the individual techniques, the "Lamendin" dental technique was most effective for individuals of ages greater than 25 years.

[Oral and dental health of a population of school children from the Zou region of Benin (1998)]. / Etat bucco-dentaire d'une population d'enfants scolarisés de la région du Zou (Bénin) en 1998.

Dental caries is becoming increasingly common in developing countries but very few attempts have been made to assess its prevalence accurately. We therefore carried out an epidemiological survey in 1998 in the south of Benin, to estimate the prevalence of dental caries in 300 school children, both boys and girls, aged 12 to 14 years. Each child underwent a dental examination and interview and the data obtained were recorded in a personal clinical record. We determined DMF index for various subgroups of children. We then analyzed DMF index and its correlation with sex, age, socioeconomic level, the urban or rural origin of the child, diet and daily dental hygiene practices. We found that mean DMF index at age 12 years was 0.83 (38.7% had dental caries and 4.4% had fillings), and thus, 61. 3% of the children were free of dental caries. We also found that 80% of the children had an accumulation of tartar. More boys than girls had dental caries. Rural children were less likely to have dental caries than urban children. The prevalence of caries appears to be low despite poor dental hygiene and a lack of dental treatment. These results conflict with those of most other studies. However, they should be interpreted with caution because the population studied was very homogeneous (selection bias), the age of the children could be no more than approximate (some were probably younger than 12 and others older than 14, because the registry system is inaccurate), there had been health education classes in some schools before the survey and it was difficult to define socioeconomic level and a sugary diet. For example, the lower socioeconomic level (no TV, radio, electricity or tap water) was probably an accurate representation of children from the rural area, whereas urban children were proud of being well-equipped and may have had a tendency to exaggerate. The prevalence of dental caries in this population is currently as low as that for most pre-industrial African countries. To avoid problems in the future, dental health services require reorganization and should stress measures for preventing dental caries: changes in dietary habits, the promotion of traditional tooth brushing practices, the systematic surveillance of dental caries at school and the removal of tartar.

Effect of pyrazole and dexamethasone administration on cytochrome P450 2E1 and 3A isoforms in rat liver and kidney: lack of specificity of p-nitrophenol as a substrate of P450 2E1.

The induction effects of pyrazole and dexamethasone (known to be specific to P450 2E1 and 3A enzymes, respectively), given alone or simultaneously, were studied in rat liver and kidney microsomes. Pyrazole treatment induced the catalytic activity and the amount of P450 2E1 enzyme in both organs. Immunoreactive P450 2E1 and 4-nitrophenol 2-hydroxylation increased 8- and 13-fold, respectively (versus control), in the kidney, but only 2.4- and 2.7-fold (versus control) in the liver after pyrazole treatment. As assessed by nifedipine oxidation activity, dexamethasone treatment increased the P450 3A catalytic activity approximately 4-fold (versus control) in the liver, but not in the kidney, suggesting that P450 3A was not inducible in the kidney. Pyrazole decreased P450 3A activity in the liver but did not modify it in the kidney. A combination of both chemicals induced both enzymes, but to a lesser extent than treatment with each single chemical compound. Furthermore, the 2-hydroxylation of p-nitrophenol, considered one of the most specific substrates for monitoring the level of P450 2E1, was mediated also by P450 3A, at least in dexamethasone-treated rats. Finally, this experimental work demonstrated that P450 3A induction is organ-specific, and it also demonstrated the lack of specificity of p-nitrophenol as a P450 2E1 substrate.

Noninvolvement of CYP2E1 in the (omega-1)-hydroxylation of fatty acids in rat kidney microsomes.

Pyrazole, acetone, and ethanol are known to induce cytochrome P450 2E1 (CYP2E1) and fatty acid (omega-1)-hydroxylation in rat liver microsomes. However, the nature of the P450 enzyme involved in this (omega-1)-hydroxylation has not been clearly established in extrahepatic tissues such as kidney. Four enzymatic activities (hydroxylations of chlorzoxazone, 4-nitrophenol, and two fatty acids) were assayed in kidney microsomal preparations of rats treated with CYP2E1 inducers. Per os treatment resulted in large increases (threefold to fivefold) in the chlorzoxazone and 4-nitrophenol hydroxylations, and up to a ninefold increase when ethanol was administered by inhalation. However, neither the omega-hydroxylation nor the (omega-1)-hydroxylation of fatty acids was modified. Immunoinhibition specific to CYP2E1 did not significantly decrease the omega and (omega-1)-lauric acid hydroxylations, while the polyclonal anti-CYP4A1 antibody inhibited in part both the omega- and (omega-1)-hydroxylations. Chemical inhibitions using either CYP2E1 competitive inhibitors (such as chlorzoxazone, DMSO, and ethanol) or P450 mechanism-based inhibitors (such as diethyldithiocarbamate and 17-octadecynoic acid) led to a partial inhibition of the hydroxylations. All these results suggest that fatty acid (omega-1)-hydroxylation, a highly specific probe for CYP2E1 in rat and human liver microsomes, is not mediated by CYP2E1 in rat kidney microsomes. In contrast to liver, where two different P450 enzymes are involved in fatty acid omega- and (omega-1)-hydroxylations, the same P450 enzyme, mainly a member of the CYP4A family, was involved in both hydroxylations in rat renal microsomes.

Both cytochromes P450 2E1 and 3A are involved in the O-hydroxylation of p-nitrophenol, a catalytic activity known to be specific for P450 2E1.

4-Nitrophenol 2-hydroxylation activity was previously shown to be mainly catalyzed by P450 2E1 in animal species and humans. As this chemical compound is widely used as an in vitro probe for P450 2E1, this study was carried out to test its catalytic specificity. First, experiments were carried out on liver microsomes and hepatocyte cultures of rat treated with different inducers. Liver microsomes from pyrazole- and dexamethasone-treated rats hydroxylated p-nitrophenol with a metabolic rate increased by 2.5- and 2.7-fold vs control. Dexamethasone treatment increased the hepatic content of P450 3A but not that of P450 2E1. Two specific inhibitors of P450 3A catalytic activities, namely, ketoconazole and troleandomycin (TAO), inhibited up to 50% of 4-nitrophenol hydroxylation in dexamethasone-treated rats but not in controls. Hepatocyte cultures from dexamethasone-treated rats transformed p-nitrophenol into 4-nitrocatechol 7.8 times more than controls. This catalytic activity was inhibited by TAO. Similarly, hepatocyte cultures from pyrazole-treated rats hydroxylated p-nitrophenol with a metabolic ratio increased by about 8-fold vs control. This reaction was inhibited by diethyl dithiocarbamate and dimethyl sulfoxide, both inhibitors of P450 2E1. Second, the capability of human P450s other than P450 2E1 to catalyze the formation of 4-nitrocatechol was examined in a panel of 13 human liver microsomes. Diethyl dithiocarbamate and ketoconazole reduced 4-nitrophenol hydroxylase activity by 77% (+/- 11) and 13% (+/- 16), respectively. Furthermore, the residual activity following diethyl dithiocarbamate inhibition was significantly correlated with seven P450 3A4 catalytic activities. Finally, the use of human cell lines genetically engineered for expression of human P450s demonstrated that P450 2E1 and 3A4 hydroxylated 4-nitrophenol with turnovers of 19.5 and 1.65 min-1, respectively. In conclusion, P450 3A may make a significant contribution to 4-nitrophenol hydroxylase activity in man and rat.

Determination of cytochrome P450 2E1 activity in microsomes by thin-layer chromatography using [2-14C]chlorzoxazone.

A thin-layer chromatographic assay was developed as an alternative method for the determination of cytochrome P450 2E1 (CYP2E1) in microsomes using [2-14C]chlorzoxazone. After incubation of microsomes with 0.125 microCi/mmol chlorzoxazone, chlorzoxazone and its single metabolite, 6-hydroxychlorzoxazone, were extracted using chloroform-2-propanol (85:15, v/v) and chromatographed on silica gel 60 F254 plates with acetone-hexane (45:55, v/v) as solvent . The plates were then exposed to X-ray film for 2 days to localize the radiolabelled chlorzoxazone and 6-hydroxychlorzoxazone. The metabolite and substrate regions were scraped and counted in a liquid scintillation analyzer. This method is sensitive enough to determine constitutive and induced CYP2E1 activities in liver or kidney microsomes. The precision of the method was similar to that of the HPLC method. The correlation coefficient between both methods was found to be 0.97 (n = 21). Therefore, the TLC method constitutes a valuable tool for the determination of chlorzoxazone metabolism in microsomes.

Cytochrome P-450 2E1 in rat liver, kidney and lung microsomes after chronic administration of ethanol either orally or by inhalation.

In this study, microsomal cytochrome P-450 2E1 (CYP2E1) contents and activities were tested in liver, kidney and lung from Wistar rats after the following treatments (1) oral administration of a 10% ethanol solution for 4 weeks; (2) pair fed controls; (3) oral administration of a 5% acetone solution for 1 week; (4) inhalation of ethanol vapour for 4 weeks. CYP2E1 activity was measured using chlorzoxazone as substrate and CYP2E1 content was measured using Western blot analysis. In addition, the cellular distribution of CYP2E1 was studied in liver, lung and kidney by immunohistochemistry. Basal liver CYP2E1 was 10-20 times lower in lung and kidney than in liver. Inhalation was clearly the most efficient way of inducing CYP2E1, probably due to the continuous and high alcohol exposure. Among the organs tested, lung appeared to be the tissue least sensitive to induction even after ethanol inhalation, suggesting the absence of local induction. After ethanol intoxication, immunostaining was increased in the centrilobular region of the liver, in the alveolar cells of the lung and in the proximal convoluted tube of the kidney. The CYP2E1 activities decreased to control values in the three tissues tested, within 24 h after cessation of intoxication.

A simple technique for age estimation in adult corpses: the two criteria dental method.

A method for age determination of adults from single rooted teeth is presented. It is based on the measurement of two dental features: periodontosis height times 100/root height (P) and transparency of the root height times 100/root height (T). These measurements are made on the labial surface of the entire tooth without section and do not require special equipment or training. The application of multiple regression analysis to a working sample of 306 teeth of known age, sex and race provided the following equation: Age (years) = 0.18 x P + 0.42 x T + 25.53. The mean error between the actual and estimated age was +/- 10 years on the working sample and +/- 8.4 years on a control sample made of 45 forensic science cases. Upper incisors showed a better precision than the other single rooted teeth and accuracy was not sex related. A comparison of the Gustafson and Lamendin methods on a control sample of 39 teeth resulted in an advantage of the latter considering the mean error on the estimation (14.2 +/- 3.4 years for Gustafson versus 8.9 +/- 2.2 for Lamendin). The Lamendin method can be practical interest for any forensic pathologist or dentist as it is fast, easy to use, and reasonably accurate except for cases of individuals under age 40 where other methods must be preferred.