Biomedical subjects
Publications and source records attributed to M Wahl.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
In the present study, the vasomotor effects of nicotine, its interaction with local chemical factors and norepinephrine, and its effects on the permeability of the blood-brain barrier (BBB) were investigated. Using perivascular microapplication, 10(-6) M nicotine was found not to exert a vasomotor effect by itself or to modify the vasodilating effect of an increase in perivascular H+, K+ and adenosine concentration. The constrictor effect of a decrease in H+, K+ or an increase in norepinephrine concentration in the perivascular space was also not altered by 10(-6) M nicotine, indicating a lack of interaction between nicotine and the compounds tested. Using cortical superfusion and intravital fluorescence microscopy nicotine (10(-7) to 10(-3) M) was also found not to affect the diameter of pial arteries during superfusion periods of 30 min each. The integrity of BBB could be demonstrated in time-matched solvent controls over 3 h using intravenously-infused FITC-labelled dextran (MW 70,000) as tracer. During cortical superfusion with 10(-7) to 10(-5) M nicotine the permeability of the BBB was not increased compared with the time-matched controls. However, during superfusion with 10(-4) and 10(-3) M nicotine, tracer extravasation could be quantified by computer-aided image analysis. The extravasation index (EI) increased by up to eight times. These data indicate that only toxic concentrations of nicotine increase BBB permeability to FITC-dextran 70,000.
To achieve a more rapid antibody response following hepatitis B (HB) vaccination, vaccine injections were given to medical students at considerably shorter intervals than usually recommended. They received 10 micrograms of the Merck Sharp & Dohme recombinant HB vaccine at time 0, 2 and 6 weeks (27 vaccinees) or were vaccinated according to the recommended schedule for pre-exposure HB prophylaxis (0, 1 and 6 months) (26 vaccinees). The short interval regimen resulted in a significantly higher frequency of protective antibody levels (greater than or equal to 10 IU/l) two weeks after the second dose of vaccine (48% vs. 4%; p less than 0.001), and all short interval vaccinees had seroconverted within two months (i. e. two weeks after the third dose). The recommended interval regimen resulted in a slower development of antibodies but significantly higher peak antibody levels after the completed three doses (p less than 0.001). The results indicate that protective antibody levels against hepatitis B virus (HBV) can be achieved more rapidly in humans through vaccination with short intervals. This short interval vaccination regimen, which has proved effective for post-exposure prophylaxis in chimpanzees, should possibly also be considered for post-exposure prophylaxis in humans, for instance after accidental exposure to HBV-contaminated blood.
Explore the source record for details and available documents.
Enantiomers of amphetamine (AM), methamphetamine (MA), 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA), and 3,4-methylenedioxyethylamphetamine (MDEA) exhibit different pharmacological properties. This may be important for the interpretation of analytical results. Plasma samples were analyzed using validated negative ion chemical ionization gas chromatography-mass spectrometry procedures. The results for clinical toxicology cases, divided into screening (SCR) and intoxication (ITX) cases, and those of driving under the influence of drugs (DUID) cases were compared. The concentrations of all enantiomers, except R-(-)-MDA and R-(-)- and S-(+)-MA, in the SCR samples were lower than in ITX and DUID samples. Differences between concentrations in ITX and DUID samples were only significant for both enantiomers of AM (DUID higher). These findings suggested impairment in drugged drivers. Different enantiomer ratios (R vs. S) were found for AM between DUID and SCR samples, for MDMA between ITX and SCR samples, and for MDA between DUID and ITX and DUID and SCR samples. Higher MDMA enantiomer ratios in SCR compared to ITX samples are in accordance with a previously described increase of those ratios over time, possibly allowing differentiation of recent from nonrecent ingestion. Pharmacokinetic analysis of a MDMA poisoning yielded elimination half-lives of 6.0 h for R-(-)-MDMA and 4.1 h for S-(+)-MDMA. The enantiomer ratios rose exponentially over time.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Bradykinin (BK) produced concentration-related relaxations of cat middle cerebral arteries and was ineffective in cat basilar arteries. On rabbit basilar arteries, BK initially produced concentration-related relaxations; however, when repeated at 2-hour intervals, BK eventually produced pure contractile responses. After preincubation of the tissues with cycloheximide, BK produced reproducible relaxation responses. The angiotensin-converting enzyme inhibitors, SQ 14,225, BPP5a, and BPP9a, had no effect on the concentration-effect curves of BK, AII, or 5-HT with any of the preparations, but responses to AI were inhibited. These results suggest that, in these tissues, angiotensin-converting enzyme is important for conversion of AI to AII, but apparently not for the degradation of BK.
Explore the source record for details and available documents.
Explore the source record for details and available documents.