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Biomedical subjects

B Lewis

Publications and source records attributed to B Lewis.

At least 361 records · Page 20Linked to original sources
PubMedDate not supplied

Same day appearance of orally administered, spermicidal 1-substituted imidazoles in dog ejaculates.

Within hours after administration of high oral doses of ketoconazole to males of various species, the intact compound appears in the seminal plasma, leading to immobilization of spermatozoa in ejaculates collected several hours later. The present report describes in vitro and in vivo characterization studies of several new compounds identified from a series of 1-substituted imidazole compounds. Relative rank order of in vitro potencies of the four compounds studied was RS-29984 greater than RS-90847 greater than RS-41353 greater than RS-68287. Oral administration of single doses of these compounds ranging between 10 and 95 mg/kg, followed by ejaculation of the animals at various times after dosing, showed that their relative potencies for decreasing sperm motility were RS-41353 greater than RS-68287 = RS-90847 greater than RS-29984. Four hours after animals were given 30 mg/kg of RS-41353, spermatozoa in the ejaculates had zero forward progression within 30 to 40 minutes after the start of ejaculation. A preliminary metabolic study indicated that the apparently greater potency of RS-68287 in vivo than in vitro was probably not due to metabolic activation. The androgen-suppressing activity of RS-29984 and RS-90847 was shown to be less than that of ketoconazole. These data indicate that orally active inhibitors of sperm motility that exert their effects after ejaculation may be feasible, and suggest that this novel approach to male contraception warrants further investigation.

Administration, Oral↗
PubMedDate not supplied

Lipoprotein concentrations in serum and in biopsy samples of arterial intima: a quantitive comparison.

Lipoprotein concentrations were compared in serum and in samples of arterial intima obtained during cardiovascular surgery. The interval between blood sampling and surgery did not exceed 48 hours. Apolipoproteins B and C, the major proteins of low density lipoprotein (LDL) and very low density lipoprotein (VLDL) respectivity, were detectable by immuno-assay in all arterial specimens. Highly significant positive correlations existed between the levels of lipoproteins in the intima and in serum. In patients with elevated serum VLDL levels (Type IV hyperlipoproteinaemia) arterial concentrations of apolipoproteins B and C were increased about two-fold; in those with raised LDL levels in serum (Type II), with or without concomitant elevation of VLDL levels, the concentration of apolipoprotein B was increased almost 5-fold in the arterial intima. The arterial wall therefore contains lipoproteins or their immunologically-similar metabolites at concentrations which are determined in part by serum lipoprotein levels.

Adult↗
PubMedDate not supplied

The relationship between legal factors and attrition from a residential drug abuse treatment program.

This article examines the legal involvement of 438 clients randomized to three- and six-month versions of a residential drug abuse treatment program with respect to early attrition (before 40 days in treatment) and later attrition (40-79 days in treatment). Concern about legal problems was reported by 21% of subjects in response to an open-ended question about factors that led to admission; 42% had other legal circumstances that were determined either from documented evidence of legal involvement from chart review or from self-report through structured questioning about legal status. For those with "concern about legal problems" the early attrition rate was 16%, compared with 33% for those with no legal factors--odds ratio (OR) .38 with 95% confidence interval (95% CI) (.20,.73) and the later attrition rate was 25%, OR .76, 95% CI (.39,1.48). Those subjects with "legal circumstances" only had an early attrition rate of 29%--OR .86, 95% CI (.54,1.37) and a later attrition rate of 19%, OR .53, 95% CI (.29,.98) compared to those with no legal factors. There was little evidence of confounding in any of these results from adjusted analyses. Findings suggest that only self-reported concern about legal status as a problem mentioned at entry to treatment is significantly associated with lower early attrition and there is no significant relationship of legal factors with later attrition.

Adult↗
PubMedDate not supplied

Do children retain what they are taught?

Burn prevention lectures instituted in early childhood education is believed to have decreased burn-related injuries in children. Validation of retention of information to verify effectiveness of school lectures is needed. A pretest and posttest were developed to measure the retention of burn prevention methods taught to students. The pretests were administered by the teachers to fourth and fifth graders (n = 500) one day before the prevention lecture. Programs were taught assembly style. The teachers were asked to reissue the posttest within 2 days after the program. The tests were then returned to the community educator. The test included 15 multiple choice questions. Questions addressed escaping a burning building and burn prevention items such as cooking, first aid tips, and other general prevention ideas. Test results showed overall improvement of scores. Additional analysis showed that though test scores improved, there was less improvement in scores of inner-city students. Pretesting and posttesting has provided valuable information regarding student learning. It has also identified target groups and areas where increased efforts of prevention programs must be directed.

Adolescent↗
PubMedDate not supplied

Epidemic perinatal listeriosis.

During the 11 months beginning in January, 1980, 22 cases of perinatal Listeria monocytogenes infection occurred at three obstetric hospitals in Auckland, New Zealand. Most cases were due to type 1b strains. Since the previous epidemic here in 1969, about one perinatal infection has been diagnosed annually in the same area. Women presented in preterm (11 of 22 cases) or term labor with signs of amnionitis (11 of 22 cases) and associated fetal distress and/or meconium-stained liquor (14 of 19 cases). A mild "flu"-like illness or urinary tract symptoms were common (18 of 22 women). Five fetal deaths occurred. Three were before 20 weeks of gestation. Most liveborn affected babies had early respiratory symptoms (12 of 14 cases). Meningitis occurred in 4 of 14 infants. There was one death. Vaginal carriage of L. monocytogenes was found in only 1 of 750 consecutive asymptomatic pregnant women who were tested at the time of the epidemic. Rectal carriage was found in 25 (3.3%). Pacific Island Polynesians were rectal carriers of L. monocytogenes and were represented among the epidemic cases more often than expected according to birth data (P less than 0.05 and P less than 0.001, respectively). The cause of the epidemic was not discovered but shellfish and raw fish consumption may have played a part.

Adolescent↗
PubMedDate not supplied

Quantitative studies of transfer in vivo of low density, Sf 12-60, and Sf 60-400 lipoproteins between plasma and arterial intima in humans.

To assess the potential of various plasma lipoprotein classes to contribute to the lipid content of the arterial intima, influx and efflux of these plasma lipoprotein fractions into and from the intima of human carotid arteries were measured in vivo. While low density lipoprotein (LDL) is known to transfer from plasma into the arterial wall, there is less information on the atherogenic potential of lipoproteins of intermediate density (Sf 12-60) or of very low density (Sf 60-400). Aliquots of the same lipoprotein (LDL, Sf 12-60 lipoprotein particles, or Sf 60-400 lipoprotein particles) iodinated with iodine-125 and iodine-131 were injected intravenously 18-29 hours and 3-6 hours, respectively, before elective surgical removal of atheromatous arterial tissue, and the intimal clearance of lipoproteins, lipoprotein influx, and fractional loss of newly entered lipoproteins were calculated. Intimal clearance of Sf 60-400 particles was not detectable (less than 0.3 microliter x hr-1 x cm-2), whereas the average value for both LDL and Sf 12-60 lipoprotein particles was 0.9 microliter x hr-1 x cm-2. Since the fractional loss of newly entered LDL and Sf 12-60 lipoprotein particles was also similar, the results suggest similar modes of entry and exit for these two particles. However, due to lower plasma concentrations of Sf 12-60 lipoproteins as compared with LDL, the mass influx of cholesterol in the Sf 12-60 particles was on the order of one 10th of that in LDL, and that of apolipoprotein B was about one 20th.(ABSTRACT TRUNCATED AT 250 WORDS)

Apolipoproteins B↗
PubMedDate not supplied

Influence of plasma lipoproteins on platelet aggregation in a normal male population.

Aggregation tests were performed on platelet-rich plasma from healthy male volunteers to determine the minimum concentration of adenosine diphosphate (ADP), epinephrine, collagen, or thrombin required to induce secondary aggregation. Platelets were also analyzed for cholesterol and phospholipid, and in some cases their membrane fluidity was determined by fluorescence depolarization of the probe, diphenylhexatriene. Concentrations of the major lipoprotein fractions in the plasma were measured and related to the sensitivity of platelets to the four agonists. Low density lipoprotein (LDL) and total cholesterol concentrations, but not high density lipoproteins (HDL) or very low density lipoproteins (VLDL), were positively correlated with sensitivity to aggregation by epinephrine, but not by other agonists. By arrangement of the lipoprotein concentration into quintiles, the effect of LDL was most striking in the lower two quintiles, where the sensitivity to adrenaline and ADP were much diminished. The middle and upper two quintiles showed a similar sensitivity. Lower platelet cholesterol/phospholipid ratios were also associated with a reduced sensitivity to epinephrine or ADP, but only at the lower end of the range. Membrane microviscosity was correlated negatively with collagen sensitivity and with VLDL cholesterol concentrations, but positively with HDL cholesterol concentrations. Platelet behavior appears, therefore, to be influenced by lipoprotein concentrations within the range found in a healthy population.

Adenosine Diphosphate↗