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Biomedical subjects

R Voigt

Publications and source records attributed to R Voigt.

At least 19 recordsLinked to original sources
PubMed1992

The effect of cigarette smoking on lymphocyte subsets and progression to AIDS in a cohort of homosexual men.

We investigated the effect of cigarette smoking on the percentage of CD4 and CD8 cells (CD4%, CD8%) within a prospective study of homosexual men in Vancouver, Canada and compared progression rates to AIDS among seroincident smokers and non-smokers. Serial measurements of CD4% and CD8% obtained from four annual visits were available for 299 men and were compared with respect to smoking status and serologic group. CD4% was significantly elevated (p less than 0.025) and CD8% was significantly lower (p less than 0.002) in seronegative smokers compared to non-smokers. However, no effect of smoking was observed in the seropositive group for either of these variables. In a prospective analysis of 122 seroincident subjects, we failed to find a significant association between smoking and progression to AIDS (p = 0.829) or Pneumocystis carinii pneumonia (p = 0.894). At 72 months, cumulative AIDS progression was 29.1% in seroincident smokers compared to 25.2% in seroincident non-smokers. These data suggest that in the absence of HIV, smoking is associated with higher CD4% and lower CD8% but these effects are not present in seropositive subjects with longer durations of infection. Cigarette smoking does not appear to be associated with an altered rate of progression to AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Across-fiber patterns may contain a sensory code for stimulus intensity.

Various models for sensory coding have used statistical approaches based on the assumption that the stimulus intensity parameter is represented in the afferent neurons as mean firing frequency. In this paper we question the assumption that this is the only code for intensity. We show that in lobster olfactory receptors narrowly tuned to hydroxyproline, an across-fiber pattern (AFP) code distinguished more concentration levels over a 5 log step range than a response magnitude code and, unlike the latter, was unaffected by response summation time. AFP discrimination of stimulus intensity appears to be based on high inter-cell response variability and low intra-cell response variability.

Animals↗
PubMed1991

[Side effects of intrauterine pessaries--a retrospective study].

Based upon a retrospective evaluation of 27,519 cycles in 932 patients, we determined the type and rate of incidence of side effects. In 57.2% of the patients, the course was without any complaints. Approximately 80% of all complications, induced by IUD, occur already during the first 3 months after insertion, with the exception of pelvic inflammation and pregnancy. 62.5% of the adnexitides and/or endometritides were observed during the 4-year observation period during the first 12 months without time cumulation; this applies likewise to the pregnancies occurring with IUD. The largest proportion of side effects were haemorrhagic disorders (33.2%), followed by recurrent pain in the lower abdomen (9.9%).

Adult↗
PubMed1991

Electrolyte transport through a cation-selective ion channel in large intestinal enterocytes of Xenopus laevis.

Electrogenic ion transport through the colon epithelium of the African clawed toad (Xenopus laevis) was investigated with electrophysiological methods in vitro. Interest was focused on a previously described phenomenon, that removal of Ca2+ from the mucosal Ringer's solution increases electrogenic sodium absorption. Our results clearly show that Ca2+ removal reveals an apical ion channel that is not a specific Na+ channel, but a non-selective cation channel with an 'apparent' ion selectivity of the order K+ greater than Na+ = Rb+ greater than Cs+ greater than Li+. This Ca2(+)-sensitive current increased linearly with the mucosal pH, and could be inhibited by other divalent cations (Mg2+, Ba2+) and the organic ion channel blockers quinidine and verapamil. The mucosal Ca2+ concentration that induced a half-maximal inhibition of the Ca2(+)-sensitive current was about 1 mumol l-1 and was independent of the mucosal pH. Owing to the high Ca2+ sensitivity, a regulation of the channel conductivity by extracellular Ca2+ is ruled out. It is concluded that this channel, which is almost identical to similar channels found in amphibian skin and bladder, acts as a pathway for cation absorbing or secreting processes. Possibly the binding of extracellular Ca2+ is related to selectivity changes of the Ca2(+)-sensitive ion channel.

Animals↗
PubMed1990

Ca-sensitive sodium absorption in the colon of Xenopus laevis.

Transepithelial electrogenic Na transport (INa) was investigated in the colon of the frog Xenopus laevis with electrophysiological methods in vitro. The short circuit current (Isc) of the voltage-clamped tissue was 24.2 +/- 1.8 microA.cm-2 (n = 10). About 60% of this current was generated by electrogenic Na transport. Removal of Ca2+ from the mucosal Ringer solution stimulated INa by about 120%. INa was not blockable by amiloride (0.1 mmol.l-1), a specific Na-channel blocker in epithelia, but a fully and reversible inhibition was achieved by mucosal application of 1 mmol.l-1 lanthanum (La3+). No Na-self-inhibition was found, because INa increased linearly with the mucosal Na concentration. A stimulation of INa by antidiuretic hormones was not possible. The analysis of fluctuations in the short circuit current (noise analysis) indicated that Na ions pass the apical cell membrane via a Ca-sensitive ion channel. The results clearly demonstrate that in the colon of Xenopus laevis Na ions are absorbed through Ca-sensitive apical ion channels. They differ considerably in their properties and regulation from the amiloride-sensitive Na channel which is "typically" found in the colon of vertebrates.

Amiloride↗
PubMed1990

[Urogynecologic follow-up examinations after radiotherapy of gynecologic malignancies].

47 women treated by radiotherapy for gynecologic malignancies have been examined urogynecologically. There are only some changes of subjective cystometric parameters (volume of the first desire to void, bladder capacity), but statistical significant changes of the parameters "compliance" and "bladder pressure at capacity". The parameters of urethrocystometry and uroflowmetry are not influenced by irradiation. The urethroscopy demonstrates a white mucosa of the bladder wall caused by irradiation fibrosis, agreeing to data reported by literature. Only 10 of the 47 patients examined had to be treated by drugs.

Adult↗
PubMed1990

[Manufacture and characterization of lyophilized suppositories].

Pharmaceutic usual hydrophilic macromolecular substances were investigated of usefulness to manufacture lyophilized suppositories contained propyphenazon or paracetamol. It was shown that gelatin, hydroxyethylcellulose and polyacrylic acid are able to form suitable solid structures.

Acetaminophen↗
PubMed1989

[Urodynamic results before and following vaginal electrostimulation in the treatment of urinary incontinence in the female].

In this study we demonstrate our first experience with vaginal electrostimulation in the treatment of stress incontinence in women. In the group of 26 incontinent female patients there was described a very good effect in all cases (42%) and a slight improvement was noted in 9 cases (34%) at the same time. Our results correspond with other similar presented studies. The clinical improvement was verified in the urodynamic study. There were noted: the increase of maximal (P less than 0.05) and closure pressure (P less than 0.05) of the urethra, the increase of transmission factor (P less than 0.01) and of maximum of EMG activity of the sphincter (P less than 0.005), as well as an improvement of compliance of the bladder (P less than 0.01) and of volume in the first desire to void (P less than 0.01). We can conclude that this method of intermittent vaginal electrostimulation is suitable in the treatment of female stress incontinence.

Adult↗