[Epidemiologic survey of medical and non-medical personnel in a public dental clinic]

Hepatitis B and C and Mycobacterium tuberculosis infection represent an occupational problem for the dentist. Few data are available in literature about the situation in our country. An epidemiological survey was carried out to evaluate the prevalence of Hepatitis B (HbsAb) and C (HCVab) markers and the exposure to Mycobacterium tuberculosis (Tine test) of the whole population of a public dental clinic (247 dental care workers). Furthermore participants were asked to fill a questionnaire to assess their vaccination status. 67,2% of the subjects were found to be positive for HbsAb (77,4% of medical personnel and 28,8% of the auxiliary medical personnel). Only one subject was found positive for anti-HCV (0,4%). 12,5% of the population showed a positive Tine test (15,4% of medical personnel and 1,9% of the auxiliary medical personnel). Our data show a difference between the percentage of subjects who were vaccinated (2,4%) and those who were positive to the Tine test (12,5%).

Comparative study of salivary and urinary fluoride levels and clearance patterns between fluoridated chewing gum and fluoride tablets in children

AIM: The aim of the present study was to compare the effect of a chewing gum containing 0.50 mg fluoride with two tablets containing 0.25 mg fluoride as NaF, on the salivary and urinary fluoride concentration in children. MATERIALS AND METHODS: Whole saliva and urine were sampled from twenty 5-9 years-old children to assess the baseline fluoride concentrations. The day after, the subjects were asked to chew the fluoridated chewing gum for 15 minutes and saliva samples were collected 5, 10, 30, 60, 120, 240 minutes after ceasing the use of the chewing gum. Urine samples were collected 1, 2, 4 and 24 hours after the use of the gum. After a washout period of one week, the subjects were recalled and were asked to completely dissolve two 0.25 mg fluoride tablets in their mouth. Saliva and urine samples were collected in the same way. Fluoride concentration in saliva and urine was determined using a fluoride specific electrode. RESULTS: No significant differences were found in the concentrations of fluoride in saliva or urine using fluoridated chewing gum and tablets. CONCLUSION: The NaF tablets and chewing gum studied had approximately the same clearance pattern in saliva and urine. These data show that the chewing gum examined could be a valid alternative to the use of NaF tablets in caries prevention.

Transfer of lindane and pentachlorobenzene from mother to newborn rabbits

After administration of gamma-hexachlorocyclohexane (lindane) (30 mg/kg) to sixteen pregnant rabbits, the transfer and distribution of this insecticide and its metabolite pentachlorobenzene, in foetuses and newborns at the 5th, 10th and 20th days after birth, were investigated. Over one lactation the mothers excreted via the milk about 30% of the lindane present in tissues at the 28th day of pregnancy. The total amount of lindane transferred via milk to 5 day-old newborns was higher than that transferred across the placenta during pregnancy. Lindane concentrations in newborns decreased in spite of the efficient transfer to off-spring by lactating mothers. This cannot be explained by growth alone and indicates that newborns are able to actively metabolize the insecticide. The pentachlorobenzene metabolite produced after lindane administration to the mothers crossed the placental barrier with difficulty during pregnancy, but was readily transferred to off-spring via milk. Pentachlorobenzene levels in neonates increased during lactation by transfer and also as a consequence of endogenous production. At the 20th day of lactation the pentachlorobenzene concentration in maternal and foetal tissues was higher than that of lindane.

Elimination of PCB congeners via milk in rabbits administered Fenclor 64

A single dose of 100 mg per kg body weight of a commercial mixture of polychlorinated biphenyls (PCB), Fenclor 64 was given intraperitoneally to pregnant rabbits. The distribution in dams and foetuses and excretion in milk was investigated for six of the congeners by quantifying them in fat from maternal adipose tissue, from whole foetuses and newborn bodies and from newborn gastric contents. The cytochrome-P-450 induction after Fenclor 64 in foetuses and suckling off-spring was followed by measuring the following hepatic mixed function oxidase (MFO) activities: p-nitroanisole-demethylase, ethoxyresorufin-deethylase, ethoxycoumarin-deethylase and NADPH cytochrome-C reductase. At the 28th day of pregnancy PCB fat concentrations in foetuses were similar to those in mothers (126.4 +/- 7.1 and 152.6 +/- 28.1 micrograms/g of fat, respectively). By the 5th day of life fat concentrations in the youngs were double those of foetuses (216.81 +/- 8.12 micrograms/g) and remained high until weaning (142.2 +/- 15.5 micrograms/g at the 20th day). PCB concentrations in mothers' fat decreased during lactation (104.1 micrograms/g at the 20th day) but at the end of the experiment they were still high (95.5 micrograms/g). The cytochrome-P-450 concentration and MFO activities in young rabbits' livers from treated dams were significantly higher than controls from the 5th (P less than 0.01) to the 10th (P less than 0.01) day of life, with the exception of NADPH-cyt-C-reductase (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative microsomal oxidation of febantel and its metabolite fenbendazole in various animal species

A comparison has been made of the in vitro metabolism of febantel (FBT) with that of one of its pharmacologically active metabolites fenbendazole (FBZ) using microsomal preparations from liver of sheep, calf, horse, pig, rat, chicken and trout. The oxidation of FBT to the corresponding sulphoxide appeared to be far more rapid with the exception of the trout, than a similar reaction with FBZ. Indeed FBT was further metabolized in several species by cyclization and further oxidation. This observation could have toxicological significance in view of the greater tetratogenic effects of the metabolite oxfendazole. Reaction rates were most rapid in pigs and sheep.

Zearanol metabolism by subcellular fractions from lamb liver

Zeranol (7-alpha-zearalanol or alpha-ZAL) metabolism in vitro by subcellular fractions (microsome and cytosol) from lamb livers was investigated. The use of a high performance liquid chromatography (HPLC) technique capable of resolving epimers, revealed that when nicotinamide adenine dinucleotide (NAD) was added as a co-factor to metabolic mixtures, the oxidized form, zearalanone (ZAN) was the major metabolite, although a small amount of 7-beta-zearalanol (beta-ZAL) was also produced. In order to confirm beta-ZAL as a product of ZAN reduction, the metabolism of the latter, by microsome and cytosol in the presence of NADH as co-factor, was investigated. The results obtained revealed that both alpha-ZAL and beta-ZAL were present at the end of the incubation, the former at a higher concentration than the latter. When NAD and NADH were added as cofactors to incubation mixtures containing alpha-ZAL, the production of beta-ZAL was increased as a consequence of the higher ZAN reduction in the presence of the reducing co-factor. Nevertheless, ZAN remained the major metabolite produced from alpha-ZAL by both the subcellular fractions investigated.

In vitro febantel transformation by sheep and cattle ruminal fluids and metabolism by hepatic subcellular fractions from different animal species

Febantel and one of its main metabolites, febantel sulphoxide, are chemically modified to only a slight extent when incubated in vitro with sheep and cattle ruminal fluids; other major metabolites, fenbendazole and oxfendazole, are respectively, oxidized to oxfendazole and reduced to fenbendazole. Febantel is negligibly metabolized by hepatic cytosol fractions but microsome preparations effect more extensive metabolic transformations. Important differences in this respect were found between microsome preparations from rat, horse, pig, cattle, sheep, chicken and trout livers.

Effect of PCB on some MFO enzyme activities in pregnant and virgin rabbits

Fenclor 64 (a PCB's commercial mixture) was administered twice i.p. to virgin and pregnant New Zealand rabbits at the dose of 100 mg/Kg to evaluate its inducing properties on the following hepatic microsomal MFO activities: p-nitro-anisole-O-demethylase, amino-pyrine-N-demethylase, acetanilide-hydroxylase and aryl-hydrocarbons-hydroxylase. The results indicate that Fenclor 64 evoked a "mixed type" induction in virgin as well as in pregnant rabbits since it increased liver weight, cytochrome P-450 levels, as well as p-nitro-anisole-O-demethylase and acetanilide-hydroxylase. Pregnancy by itself affects only amino-pyrine-N-demethylase levels.

The metabolism of zearalenone in subcellular fractions from rabbit and hen hepatocytes and its estrogenic activity in rabbits

The in vitro reduction of zearalenone (ZEN) by subcellular fractions from hen and rabbit hepatocytes clearly shows species-specific differences in the cofactor requirements, rate of metabolism and production of metabolites. The presence of NADH as cofactor in the reaction mixtures enhanced only the reducing activity of the microsomal fraction from rabbit hepatocytes, while NADPH enhanced the reducing activities of the cytosolic fraction from rabbit and both the microsomal and cytosolic fractions from hen hepatocytes. Furthermore, we observed that hen hepatocytes metabolize faster and produce beta-zearalenol (ZEL) as the major metabolite, whereas rabbit hepatocytes metabolize ZEN slowly and mainly into alpha-ZEL, the more uterotrophic metabolite. These last findings are closely related to the higher sensitivity to ZEN estrogenic effects observed in rabbits during the toxicity test involving p.o. administration of the mycotoxin to the animals at 3 dosage levels (0.1, 1, 2 mg/kg body wt).