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PubMed1987

A cohort study on vinyl chloride manufacturers in Italy: study design and preliminary results.

A cohort mortality study of 5000 vinyl chloride manufacturers is ongoing in 9 Italian plants. They represent the entire workforce of those ever employed in the production of the monomer and its polymerization. The objectives of the study are to investigate the mortality of the exposed population and to clear up the carcinogenic spectrum of vinyl chloride. This article gives the results for 3 out of 9 plants, Rosignano, Ferrara and Ravenna, which represent about 25% of the total cohort. The expected deaths have been calculated using the mortality rates of the Italian population. For the deceased persons information from the death certificates were used in the analysis of mortality; additional clinical and pathological data were collected (best pathological evidence, b.p.e.). In Ferrara a statistically significant excess for all malignant tumors and lung cancer was detected. In Rosignano and Ravenna the number of observed deaths were small and therefore no comments can be made on cancer mortality. The cohort study is ongoing in the 6 remaining cohorts and the future analysis will consider duration and level of exposure and latency.

Adult↗
PubMed1980

The role of respiration in vinyl chloride monomer excretion in rats.

1, 5 and 10 mg/kg vinyl chloride monomer (VCM) in aqueous solution were injected i.v. into male rats with cannulated tracheas. Respiratory activity was regulated to permit investigation of the effect of modifying pulmonary ventilation on VCM excretion in blood and expired air assayed at different intervals for VCM. VCM excretion rate was found to be directly proportionate to pulmonary ventilation. When respiration was stopped for 1 min after VCM injection, there was no decrease in blood BCM, the main route of elimination of i.v. injected VCM thus being pulmonary.

Animals↗
PubMed1980

Pharmacokinetics of vinyl chloride in the Rhesus monkey.

The metabolic elimination of vinyl chloride in Rhesus monkeys is a dose-dependent, satruable process, as in rats. Below 200-300 ppm of vinyl chloride (VC) in atmosphere, elimination obeys a first-order law; the clearance rate is much closer to that found in man than the values for rats, mice and gerbils. The maximal velocity of metabolic elimination of VC at high concentrations in Rhesus monkeys is only about half that of rats when related to kg body weight. It s suggested that Rhesus monkeys mimic the quantitative aspects of VC metabolism better than rats or mice.

Animals↗
PubMed1981

Effects of 4-vinylcyclohexene and its main oxirane metabolite on mouse hepatic microsomal enzymes and glutathione levels.

When 4-vinylcyclohexene (VCHE) and 4-vinylcyclohexene monoxide (VCM) were administered to mice at 500 mg/kg, cytochrome P-450, cytochrome b5, NADPH-cytochrome c reductase and aminopyrine-N-demethylase and epoxide hydrolase were induced. Doses of 500 mg/kg of VCHE, VCM and 4-vinylcyclohexene diepoxide depleted rapidly hepatic reduced glutathione levels suggesting that glutathione is probably involved in the metabolism of VCHE.

Animals↗
PubMed1983

Lack of dominant lethal effects in male CD-1 mice after short-term and long-term exposures to vinyl chloride monomer.

Dominant lethal studies were conducted with vinyl chloride monomer (VCM) in male CD-1 mice, using short-term (10 000 ppm, 4 h/day, for 5 days) and long-term (5000 ppm, 4 h/day, 5 day/week, for 10 weeks) exposures. There was no evidence of dominant lethal effects due to VCM in either case. Semen examination of male mice after long-term exposure failed to reveal any alteration in sperm motility and shape. Sporadic appearance of giant cells was observed in the testes of males exposed to VCM, but was not considered to affect spermatogenesis.

Animals↗
PubMed1985

Vinyl acetate: DNA-binding assay in vivo.

The question of carcinogenicity of vinyl acetate led us to perform a DNA binding assay in vivo in rats, using 14C-labelled vinyl acetate. After administration of [14C]vinyl acetate to male and female Fischer-344 rats, either orally or by inhalation, no specific hepatic DNA adducts, known to occur after administration of labelled vinyl halides or vinyl carbamates, could be detected in hepatic tissues.

Animals↗
PubMed1989

Increased alkylation of liver DNA and cell turnover in young versus old rats exposed to vinyl chloride correlates with cancer susceptibility.

To investigate the factors responsible for the high sensitivity of the livers of young rats to the carcinogenic stimulus of vinyl chloride (VC) adult and 11-day-old Wistar rats were exposed to [1,2-14C] VC. Adult rats received either a single 6-h exposure, or 2 single 6-h exposures separated by a treatment-free time interval of 15 h. Eleven-day-old rats received 2 single 6-h exposures, according to the same treatment schedule. The animals were sacrificed 1 h after the end of the corresponding exposure period; liver DNA was isolated, enzymatically hydrolyzed and analyzed by column chromatography. Incorporation of [14C]VC-derived radioactivity into the physiological deoxyribonucleosides (presumably reflecting the activity of DNA replication) was observed for all three sets of experiments. Virtually no difference in 14C-incorporation was observed between adult rats sacrificed immediately after one single 6-h exposure to [14C]VC and those which received a second exposure on the following day. In contrast, an about 8-fold increase in 14C-incorporation into the physiological purines of DNA of young versus adult rats was detected. This difference is indicative of a significantly elevated DNA synthesis/cell replication in the liver of young (11-d) rats. Radioactivity associated with 7-(2-oxoethyl)guanine was taken as an indicator of DNA alkylation by [14C]VC. Analysis of 7-(2-oxoethyl)guanine revealed that in adult animals the amount of this alkylation product formed is increased by a second exposure to VC. About 5-fold of the amount of 7-(2-oxoethyl)guanine present in adults could be determined in liver DNA of young (11-d) animals exposed under the same exposure conditions. Our results suggest that the high sensitivity of young rats to VC-induced hepatocarcinogenesis can reasonably be explained by enhanced DNA-alkylation and by increased cellular proliferation at an early age.

Age Factors↗
PubMed1985

Reversed-phase high-performance liquid chromatographic separation of molecular species of alkyl ether, vinyl ether, and monoacyl lysophospholipids.

An isocratic reversed-phase high-performance liquid chromatographic method was developed which resolved individual molecular species of choline and ethanolamine lysophospholipids utilizing a C13 bonded porous silica stationary phase with a mobile phase comprised of methanol--water--acetonitrile (57:23:20) containing 20 mM choline chloride. Solute retention was primarily determined by hydrophobic interactions with the stationary phase permitting separation of individual molecular species of lysophospholipids according to the composition of the aliphatic chain and the nature of its covalent attachment to the sn-1 hydroxyl group. The elution profile of unsaturated monoacyllysophospholipid or lysoplasmalogen molecular species was readily obtained by measuring UV absorbance at 203 nm. Identification of column eluates containing saturated monoacyl and alkyl ether lysophospholipids was possible utilizing relative retention factors that were obtained for the majority of molecular species present in animal tissues.

Animals↗
PubMed1989

A collaborative study of the analysis of doxycycline hyclate by high-performance liquid chromatography on polystyrene-divinylbenzene packing materials.

An improved method for the analysis of doxycycline hyclate by high-performance liquid chromatography using polystyrene-divinylbenzene column packings is described. The separation obtained with this method was compared with that of other, recently described methods. The improved method was examined in a collaborative study involving five separate laboratories, using 11 different columns and four discrete samples. The main component and impurities were determined. An analysis of variance showed absence of consistent laboratory bias and presence of significant laboratory-sample interaction. Estimates for the repeatability and reproducibility of the method, expressed as relative standard deviations (RSD) of the result of the determination of doxycycline, were found to be 0.9 and 1.2%, respectively.

Chromatography, High Pressure Liquid↗
PubMed1988

Protection by latex or vinyl gloves against cytotoxicity of direct bonding adhesives.

The cytotoxicity of orthodontic bonding agents (OBAs) has been demonstrated in both animal and in vitro studies. Many practitioners and their assistants have experienced contact dermatitis of the fingers following contact with OBA. Latex gloves have also been reported to cause similar symptoms in several reports. The purpose of this study was to evaluate and quantify the toxic effects of latex and vinyl gloves, several OBAs, and combinations of these in vitro to determine the kind of glove that should by worn by practitioners when manipulating an OBA. It was determined that when OBAs are applied to washed latex, the combined toxic effect on cultured cells exceeded that of the washed gloves alone. However, when vinyl glove material instead of latex was tested, the toxic effects decreased more than 50%. Therefore, we suggest that practitioners who experience contact dermatitis in orthodontic practices wear vinyl gloves instead of latex, especially when manipulating OBAs. We also acknowledge the need for further research on the subject.

Adhesives↗
PubMedDate not supplied

Destruction of preantral follicles in adult rats by 4-vinyl-1-cyclohexene diepoxide.

4-vinyl-1-cyclohexene diepoxide (VCD) is known to destroy oocytes in ovaries of immature rats. Since ovaries functionally differ between immature and adult animals, we examined the effect of VCD on oocytes in adult rats. Adult (58 days) and immature (28 days) rats were injected daily (30 days) with vehicle or VCD. Each group contained 10 rats. During this time, cyclicity was determined daily by vaginal cytology. Animals were terminated on day 31 and tissues were collected. Oocytes were counted; livers, spleens, and uteri were weighed. VCD reduced the number of regular estrous cycles/30 days in adults, but not immature rats (n = 20, P < 0.05). VCD reduced the number of oocytes in adult and immature rats (n = 20, P < 0.05). Liver, spleen, or ovarian weights were not affected by VCD in either group. VCD reduced uterine weight in adult (n = 20, P < 0.05) but not in immature rats. These results demonstrate that VCD decreases uterine weight in adult rats and as with immature rats, selectively destroys oocytes in ovaries of adults.

Animals↗