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Biomedical subjects

R Pohl

Publications and source records attributed to R Pohl.

At least 37 records · Page 2Linked to original sources
PubMed1993

Beta-receptor responsiveness after desipramine treatment.

To examine whether a tricyclic antidepressant affects the functional response to a beta-receptor agonist in man, the response of heart rate, blood pressure, and plasma cAMP to isoproterenol was measured in 14 normal controls taking 75 mg desipramine daily. Desipramine significantly increased the bolus dose of isoproterenol needed to increase heart rate by 25 bpm at 14-30 days but not at 3-8 days. During infusions of isoproterenol, the increase in systolic blood pressure was blunted at both 3-8 days and 14-30 days, while the decrease in diastolic blood pressure was unaffected. Blood pressure findings were not affected by preadministration of bethanechol. In ten controls, isoproterenol infusions increased plasma cAMP, but this was unaffected by desipramine treatment. These findings suggest a decrease in the functional response of beta 1, but not beta 2, receptors after treatment with desipramine.

Adult↗
PubMed1993

Intravenous sodium lactate decreases plasma GABA levels in man.

Gamma aminobutyric acid (GABA), an inhibitory neurotransmitter, may play an important role in anxiety. We studied changes in plasma GABA levels in nine healthy subjects before and after infusions of sodium lactate and dextrose. Plasma GABA significantly decreased during infusions of sodium lactate (109.3 +/- 4.4 versus 91.6 +/- 5.1 pmol/ml; P = 0.0001) but not during infusions of dextrose.

Adult↗
PubMed1993

Decreased heart rate variability in panic disorder patients: a study of power-spectral analysis of heart rate.

We have previously found decreased standard deviations and mean consecutive differences of R-R intervals in panic disorder patients in standing posture, compared with control subjects. In the present study, we used spectral analysis of heart rate variability to examine autonomic function in 21 panic disorder patients and 21 normal control subjects. Patients had a significantly lower standard deviation of heart rate in supine as well as standing postures. Absolute low frequency power (0.01-0.05 Hz) was also significantly lower in panic disorder patients in standing postures. Upon standing, the panic disorder patients had significantly higher relative mid-frequency power (0.07-0.15 Hz). During a standing deep-breathing condition at six breaths per minute, the patients had a significantly decreased absolute and relative mid-frequency (0.07-0.15 Hz) power compared with control subjects. These findings suggest a decrease in cholinergic and a relative increase in adrenergic responsiveness in panic disorder patients compared with control subjects.

Adrenergic Fibers↗
PubMed1993

Fractal dimension of heart rate time series: an effective measure of autonomic function.

Previous studies suggested that heart rate (HR) time series may be more appropriately analyzed by nonlinear techniques because of the nonlinear nature of these data. In this study, we quantified the complexity of the HR time series, using fractal dimension, a previously described measure developed to study axonal growth, which quantifies the space-filling propensity and convolutedness of a waveform, and compared these results with another recently used measure, approximate entropy. Fractal dimension and approximate entropy of HR time series (unfiltered) correlate highly with each other and also with the high-frequency power (0.2-0.5 Hz) and, hence, appear to reflect vagal modulation of HR variability. These measures were also statistically more consistent and effective than measures of spectral analysis. Fractal dimension of the midfrequency time series of HR (filtered with a pass band of 0.05-0.15 Hz) also appears to be a statistically effective measure of relative sympathetic activity, especially in the standing posture.

Adult↗
PubMed1993

Changes in appetite and weight during the pharmacological treatment of patients with panic disorder.

Antidepressants reportedly increase appetite, carbohydrate craving and weight in some patients with depression and panic disorder. This paper presents the results of changes in appetite and weight in patients with panic disorder treated with imipramine, diazepam or placebo in a double-blind prospective study. Forty-four patients with panic disorder were randomly assigned imipramine, diazepam and placebo. The investigators monitored weight and the patients rated their appetite and cravings during the eight week study. No significant increases in weight or appetite were found in the patients with panic disorder patients.

Adult↗
PubMed1993

Sexual dysfunction during antidepressant treatment.

BACKGROUND: The reported incidence of sexual dysfunction associated with antidepressant medication varies from 1.9% to 92%. The majority of studies reporting incidences were not systematically conducted. METHOD: We interviewed 60 patients (22 men and 38 women, with anxiety and mood disorders) who were being treated with various antidepressants. We used a questionnaire focused on sexual side effects and other side effects. RESULTS: The incidence of sexual dysfunction during antidepressant use in our study is 43.3%. The sexual dysfunction was not limited to any particular diagnostic group nor to any particular antidepressant. There was no significant correlation between sexual dysfunction and anticholinergic side effects. The incidence of painful orgasm with antidepressants was 18% among males in our study. CONCLUSION: The relatively high incidence of sexual dysfunction associated with antidepressant treatment in this systematic study emphasizes the importance of a detailed inquiry about sexual side effects as this interferes with treatment compliance.

Adult↗
PubMed1992

Freeze-substitution of chemically stabilized samples for biological field emission scanning electron microscopy.

The high resolution imaging capabilities of modern field emission scanning electron microscopes require adequately improved tissue preparation procedures to prevent the collapse of macromolecular structures and the extraction of molecules. A routine cryo-stabilization technique is described which utilizes chemical crosslinking and cryo-dehydration for mechanical and chemical stabilization of protein and lipid structures and increase of electrical conductivity of the sample. Thiocarbohydrazide (TCH) serves as a general mordant for osmium tetroxide crosslinking. However, extensive washing after all impregnation steps is necessary to dissolve unspecific osmium black precipitations at the sample surface. Collagen I aggregates showed increased stability against collapse after TCH osmification alone, whereas pulmonary surfactant liposomes require additional freeze-substitution in methanol and Freon 113 for stabilization during critical point drying. Environmental scanning electron microscopy (at water vapor pressures of 5-10 torr within the specimen chamber) was used to control, in the wet phase, the stabilization procedure at the level of chemical crosslinkage. It could be confirmed that tannic acid, often used to stabilize lipids, leads to artificial rearrangement of bilayered liposomes into compact presumable multilayered bodies, whereas the TCH osmification preserved liposome structures and their aggregates. The increase of electrical conductivity of sliced tissue was demonstrated on kidney. Support technologies for the cryo-stabilization procedures are described in detail, as well as simple routines for first stabilization trials with new samples. On pulmonary tissue, the excellent preservation of alveolar shape and fine structures of intermediate forms of surfactant are described.

Animals↗
PubMed1992

Smoking in patients with panic disorder.

We compared smoking prevalence in 217 patients with panic disorder with that in 217 age- and sex-matched control subjects who were obtained by telephone survey from the same neighborhoods. Data were obtained for current smoking habits and smoking status at either the onset of illness (patients) or 10 years previously (control subjects). Patients had been ill for 10.6 (SD = 10.0) years. Female patients with panic disorder had a significantly higher smoking prevalence at the onset of their illness than did control subjects 10 years previously (54% vs. 35%). The current smoking prevalence for female patients was also significantly higher than that of control subjects (40% vs. 25%). Male smoking rates did not differ between patients and control subjects. Caffeine use did not appear to explain these findings. These data suggest a link between smoking behavior and panic disorder in women.

Adult↗
PubMed1992

Effects of yohimbine on heart rate variability in panic disorder patients and normal controls: a study of power spectral analysis of heart rate.

We studied the effects of yohimbine on heart rate (HR) variability in 13 normal controls and 13 patients with panic disorder. Yohimbine produced a significant increase in SD of HR in standing posture in both patients (p = 0.01) and normal controls (p = 0.025). Panic disorder patients had a significant increase in standing absolute midfrequency (MF) power (0.07-0.15 Hz) after administration of yohimbine (p = 0.002). The ratio of post- to preyohimbine standing MF power (0.07-0.15 Hz) during standing was significantly higher in patients as compared with controls (2.3 +/- 1.08 vs. 1.33 +/- 0.38; p = 0.01), which suggests an increased responsivity of panic disorder patients to the adrenergic effects of yohimbine.

Adult↗
PubMed1992

Leftward shift of R-axis on electrocardiogram in patients with panic disorder and depression.

In a prospective study, we have compared R-axis on routine electrocardiograms of panic disorder patients (n = 52) with that of depressed patients (n = 41) and normal controls (n = 65). All subjects were physically healthy and were normotensive. There was a significant leftward shift of R-axis in both depressed and panic disorder patients compared to normal controls. The implications of these findings are discussed.

Adult↗
PubMed1992

Effect of imipramine treatment on heart rate variability measures.

Recently, heart rate (HR) variability has received considerable attention, and a decreased HR variability has been linked to a significant risk of cardiovascular illness. We have previously reported such a decreased variability in panic disorder patients. In this study, we report on HR variability in 12 depressed and 6 panic disorder patients at baseline and 1 and 3 weeks of treatment with imipramine as measured by the standard deviation, mean consecutive difference and the standard deviation of the mean consecutive difference of the R-R intervals in supine, supine deep breathing and standing postures. In all subjects, imipramine (mean dose: 70 mg/day) produced a significant decrease in heart rate variability at week 3 as measured by the above variables. This decrease in HR variability during imipramine treatment is probably due to its anticholinergic effects.

Adult↗
PubMed1992

Effects of clonidine on heart rate variability.

We compared the effects of intravenous infusions of clonidine and placebo on heart rate variability in 10 healthy male controls. Clonidine produced a significant decrease in blood pressure and significantly decreased the heart rate variability during quiet standing.

Adult↗
PubMed1991

Heart rate variability in patients with major depression.

We have previously reported decreased heart rate variability upon standing in panic disorder patients compared with controls. In this study, we extend our report to include patients with major depression (n = 19). Compared to normal controls (n = 20) and panic disorder patients (n = 30), there was no significant difference in the immediate changes in heart rate upon standing in the depressed group. The standing heart rate variability (R-R variability) was significantly lower in panic disorder patients compared to both normal controls and depressed patients as indicated by the corrected standard deviations, the corrected mean consecutive difference, the corrected standard deviation of the mean consecutive difference of the R-R intervals, and the high frequency variability in successive R-R intervals, suggesting an increased vagal withdrawal in panic disorder patients, especially upon standing. There was no significant difference in any of the heart rate variability measures between depressed patients and normal controls.

Adult↗
PubMed1991

The changes of thyroid hormone during pharmacological treatment of panic disorder patients.

1. Because imipramine has lowered T4 in uncontrolled studies we examined the effect of imipramine on serum thyroid levels in panic disorder patients in a double-blind placebo and diazepam treatment controlled study. 2. Treatment with imipramine (10 subjects) was associated with a significant decrease of T4 and FTI and treatment with diazepam (8 subject) was associated with a significant decrease of T4. However, there was no significant difference across treatment groups. 3. This finding suggests that previously reported decreases in thyroid hormones during antidepressant therapy may be due to nonspecific effects of treatment rather than to the drug itself.

Adult↗