Elimination kinetics and protein binding of theophylline in the rabbit.
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Biomedical subjects
Publications and source records attributed to D C May.
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Phosphonoacetic acid (PAA) was found to inhibit in vitro varicella-zoster virus (VZV) replication. At 100 microng/ml, PAA blocked the development and spread of VZV cytopathology in both growing and contact-inhibited cultures. Formation of virus plaques by infected cells and cell-free virus was effectively blocked at concentrations as low as 25 microng/ml. The development of nuclear and cytoplasmic virus antigens was also inhibited by PAA. Inhibition by PAA suggests that VZV DNA replication, like that of other herpes-viruses, involves a virus-specific DNA polymerase.
Enhanced detection of large-plaque variants of Western equine encephalitis virus in the presence of large numbers of small-plaque Western encephalitis virus was achieved by using higher bicarbonate concentrations in the agar-overlay medium and increasing concentrations of CO(2) in an enclosed environment during the time plaques were developed with neutral red. By this technique we were able to detect large-plaque mutants in cloned small-plaque suspensions for the first time and to show an increase in detectable plaque progeny in plaques developed by neutral red. Further increase in the number of progeny per plaque was determined by assaying extracts of agar overlaying cultures containing known numbers of plaques. The significance of these findings for potential use in mutational studies is discussed.
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The effects of three erythromycin preparations on theophylline elimination kinetics were examined in 23 male subjects. Subjects received 6 mg/kg of the theophylline elixir orally and elimination kinetics were determined. The population was then randomized to receive either a lactose placebo, erythromycin base, erythromycin stearate, or erythromycin ethylsuccinate. Each 250-mg preparation was given four times a day for six days. On day seven, a repeat kinetic study was performed. The mean theophylline half-life of controls was 7.8 +/- 2.6 hours. The half-life increased significantly in all erythromycin treatment groups. The increase for the base, stearate, and ethylsuccinate groups was 51.7, 21.3, and 60.3 per cent, respectively. The total body theophylline clearance decreased significantly in all treatment groups. This was not associated with biochemical evidence of hepatitis. Three of four smokers who received erythromycin manifested no increase in theophylline half-life, in contrast to one of 13 nonsmokers. There was no difference in the percentage theophylline bound to serum protein for any of the erythromycin treatment groups or controls as determined by ultracentrifugation.
This study reports two occupational deaths resulting from exposure to fluorocarbon-113 (1,1,2-trichloro-1,2,2-trifluoroethane; FC-113) in enclosed and confined spaces. One incident involved a worker who was exposed to FC-113 after entering a small degreasing tank to clean it. The second case involved a significant spill of FC-113 onboard a marine vessel. The incidents are compared to other fatal exposures.
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CONTEXT: Teenagers' communication with their partners about sex and their use of condoms may be influenced by the discussions teenagers have with their parents about sex. However, little is known about the process of parent-teenager communication on this topic. Understanding both what parents discuss with their children and how they discuss it may lead to a greater understanding of teenagers' sexual behavior. METHODS: Interviews were conducted with 372 sexually active black and Hispanic youth aged 14-17 from Alabama, New York and Puerto Rico. Regression analyses were used to examine parent-teenager discussions about sexuality and about sexual risk, and parental communication skills as predictors of teenagers' discussions about sexual risk with a partner and teenagers' condom use. RESULTS: Parent-teenager discussions about sexuality and sexual risk were associated with an increased likelihood of teenager-partner discussions about sexual risk and of teenagers' condom use, but only if parents were open, skilled and comfortable in having those discussions. Teenagers' communication with their partner about sexual risk also was associated with greater condom use, but the relationship between parent-teenager communication and teenagers' condom use was independent of this association. CONCLUSIONS: The influence on teenagers of parent-teenager discussions about sexuality and sexual risk depends on both what parents say and how they say it. Programs that foster parent-teenager communication about sexuality and sexual risk must emphasize both of these aspects.