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Biomedical subjects

R Berchou

Publications and source records attributed to R Berchou.

At least 19 recordsLinked to original sources
PubMed1996

Effects of lactate on cross-spectral analysis of heart rate, blood pressure, and lung volume in normal volunteers.

Baroreceptor reflex sensitivity, coherence functions, and transfer functions between respiration and heart rate, and between respiration and blood pressure, were studied in nine normal volunteers before and after intravenous sodium lactate infusions. Cross-spectral analysis was used to examine heart rate, finger blood pressure, and respiration obtained with the subjects in a supine posture during spontaneous breathing. Sodium lactate produced a significant decrease of the modulus between respiration and heart rate (beats/min/l). There was no such change for the placebo infusions. The absence of a significant difference in the modulus between systolic blood pressure and heart rate for placebo or lactate indicated that there were no significant changes in the baroreceptor sensitivity index. These findings suggest that lactate infusions are associated with a decrease in cardiac vagal function.

Adult↗
PubMed1995

Effects of isoproterenol infusions on heart rate variability in patients with panic disorder.

Some evidence suggests that patients with panic disorder have a decreased cardiac vagal and a relatively higher sympathetic activity. In this study, spectral analysis of the time series of heart rate before and after isoproterenol infusions was used to study heart rate variability in six panic disorder patients and 11 normal control subjects. These preliminary data reveal a significant increase of sympathovagal ratios only in the patient group after isoproterenol administration. The findings suggest a relative increase in cardiac sympathetic and a relative decrease in cardiac vagal function in patients with panic disorder during isoproterenol infusions.

Adrenergic beta-Agonists↗
PubMed1994

Lactate-induced anxiety after imipramine and diazepam treatment.

To examine the effect of treatment on lactate-induced anxiety in a controlled study, we infused 44 panic disorder patients with lactate and placebo before and after eight weeks of double-blind treatment with imipramine, diazepam, or placebo. During treatment, both imipramine and diazepam groups improved more than the placebo group. After treatment, patients in both the imipramine and diazepam groups had significantly less anxiety than the placebo patients when reinfused with lactate. In addition, imipramine decreased posttreatment panic attack frequency and diazepam decreased the perceived severity of posttreatment lactate-induced panic attacks. This study demonstrates that diazepam, like imipramine, is an effective treatment for panic disorder, and that both imipramine and diazepam blunt lactate-induced anxiety in a placebo controlled study.

Adolescent↗
PubMed1994

Sodium lactate increases sympathovagal ratios in normal control subjects: spectral analysis of heart rate, blood pressure, and respiration.

We used spectral analysis of heart rate (HR), blood pressure (BP), and respiration to examine the effects of lactate on cholinergic and adrenergic influences on HR and BP variability, a technique found to be very useful in cardiovascular research. We specifically used high frequency (0.2-0.5 Hz) and midfrequency (0.07-0.15 Hz) powers to study cholinergic and adrenergic activity in nine normal control subjects before and after lactate and placebo infusions. Our results demonstrate a marked decrease in cholinergic activity and a significant increase in sympathovagal ratios of HR modulation after lactate infusions. This altered sympathovagal balance may contribute to the panicogenic effects of lactate in panic disorder patients.

Adult↗
PubMed1994

Lactate sensitivity and cardiac cholinergic function in panic disorder.

Using spectral analysis of the continuous time series signal before and during lactate and placebo infusions, the authors studied heart rate variability in six patients with panic disorder and nine normal comparison subjects. The decrease in high-frequency (0.20-0.50 Hz) power and the increase in sympathovagal ratios (mid-frequency [0.07-0.15 Hz] to high-frequency powers) after the administration of intravenous sodium lactate were significantly greater in the patients than in the normal subjects after correction of the values for the amount of lactate infused. This result suggests an exaggerated cardiac vagal withdrawal in patients with panic disorder during lactate infusions.

Adult↗
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↗
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

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↗
PubMed1990

Somatic and psychological symptoms during isoproterenol-induced panic attacks.

To determine which symptoms characterized isoproterenol-induced panic attacks, we analyzed the presence of panic attacks in 54 panic disorder patients who panicked, 24 patients who did not panic, and 37 controls who did not panic during isoproterenol infusions. The increases over the baseline of the symptoms shortness of breath and fear of going crazy were highly associated with panicking patients when compared to nonpanicking patients and nonpanicking controls. The increases of the symptoms trembling and shaking, generally nervous, and fear of going crazy were highly associated with patients when compared to controls. The possibility of a cognitive theory of panic attacks is discussed.

Adolescent↗
PubMed1990

Monosodium glutamate and tranylcypromine administration in healthy subjects.

The authors administered 400 to 1600 mg of monosodium glutamate and placebo to five healthy males while they were medication-free and again while they were receiving the monoamine oxidase inhibitor tranylcypromine, after having received the drug daily for at least 2 weeks. Monosodium glutamate produced no consistent changes in either blood pressure or heart rate in subjects receiving tranylcypromine. Spontaneous hypertensive episodes were observed in two subjects. These blood pressure increases also occurred with tranylcypromine alone and were unrelated to monosodium glutamate administration. Diet was not violated during these episodes.

Adult↗
PubMed1988

Isoproterenol-induced panic attacks.

Eighty-six panic disorder patients and 45 nonpsychiatric controls were infused with isoproterenol at a rate of 1 microgram/min for up to 20 min in a placebo-controlled, double-blind study. Sixty-six percent of panic disorder patients experienced panic attacks during isoproterenol infusions, compared to 16% during placebo infusions. Nine percent of control subjects panicked with isoproterenol, but none panicked with placebo. Patients were more sensitive than controls to the anxiogenic effects of isoproterenol, as measured by subject self-ratings on a panic description scale. The frequency of panic attacks induced in patients was related to the dosage of isoproterenol; 79% of the patients who received a mean of 18.5 ng/min/kg of isoproterenol panicked. The panic attacks experienced by patients during isoproterenol infusions were similar to those experienced during placebo infusions.

Adolescent↗
PubMed1988

Sodium lactate infusions after treatment with tricyclic antidepressants: behavioral and physiological findings.

Fourteen patients with panic disorder were infused with sodium lactate both before and after treatment with tricyclic antidepressants. All patients had panic attacks before treatment, and only five after treatment. There was a significant decrease in measures of anxiety prior to and during infusions after treatment. The patients were able to tolerate more lactate during reinfusions. The comparison of reinfusion panickers and nonpanickers revealed that the reinfusion panickers had higher levels of anxiety, as measured by psychological symptoms on the Panic Description Scale, during both their pretreatment and posttreatment infusions. Tricyclic antidepressants appear to increase the threshold for lactate-induced panic attacks.

Antidepressive Agents, Tricyclic↗
PubMed1988

Effects of laboratory-induced panic-anxiety on subsequent provocative infusions.

The effects of infusion-induced panic-anxiety on subsequent pre-infusion anxiety ratings and infusion-induced panic attacks were studied in 64 panic disorder patients, in a double-blind randomized study using sodium lactate, isoproterenol, and placebo infusions. While there was a decrease of preinfusion anxiety from one infusion to the next infusion both for panickers and nonpanickers, there was no evidence of either a significant decrease or an increase in the frequency of subsequent panic attacks. These results suggest that there is neither a desensitizing nor a sensitizing effect of pharmacologically induced panic attacks on subsequent infusions in a serial three-infusion design.

Adult↗
PubMed1988

Follow-up study of control subjects with lactate- and isoproterenol-induced panic attacks.

Eleven of 45 normal control subjects experienced panic attacks during lactate and/or isoproterenol infusions. Ten of the 11 subjects were followed up for a mean period of 32.5 months. Two subjects reported the development of spontaneous panic attacks during the follow-up period; one related the development of these attacks to the infusion experience. Neither subject met DSM-III criteria for panic disorder either before or after the infusions. Twenty-six healthy control subjects who did not experience panic attacks during the infusion experience did not report any attacks during a follow-up period of 31.1 months.

Adult↗
PubMed1988

Preinfusion anxiety and laboratory-induced panic attacks in panic disorder patients.

Seventy panic disorder patients participated in a double-blind, placebo-controlled, randomized infusion study in which sodium lactate and isoproterenol were used to induce panic anxiety. Patients who panicked during lactate, isoproterenol, and placebo infusions generally had higher preinfusion anxiety scores. These findings held true irrespective of the order the infusions were given. Stepwise multiple regression analyses comparing panickers with nonpanickers as the criterion variable revealed that the items "afraid of going crazy," "feeling unsteady," and "feeling paralyzed" on the Panic Description Scale had the highest predicting values.

Adolescent↗