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Biomedical subjects

S Gabriel

Publications and source records attributed to S Gabriel.

At least 73 records · Page 4Linked to original sources
PubMed1994

Very slow oscillations of activity in geniculate neurones of urethane-anaesthetized rats.

The spontaneous activity of neurones of the dorsal lateral geniculate nucleus (dLGN) in urethane-anaesthetized rats was examined for the presence of very slow oscillatory activity. Fifty-four of the 86 dLGN neurones (63%) recorded extracellularly displayed oscillatory activity in the 0.02-0.03 Hz range. Similar very slow oscillations were observed in the ventral part of the LGN and the nucleus lateralis posterior (LP), but not in the hippocampus. Diffuse light stimuli dampened or blocked these oscillations in 23 of the 29 neurones tested. In a second group of experiments (iontophoretic studies) the very slow oscillatory activity was efficiently blocked by N-methyl-D-aspartate.

Action Potentials↗
PubMed1994

Effects of ipsapirone in healthy subjects: a dose-response study.

A dose-response study of ipsapirone (IPS), a 5HT1a partial agonist, was conducted in healthy male subjects. IPS was administered in doses of 5, 10 and 20 mg PO in a placebo-controlled, double-blind design to 15 subjects on 4 test days separated by at least 3 days. Oral temperature, ACTH, cortisol, prolactin, blood pressure, pulse rate and behavioral variables were assessed every 30 min for 3 h after administration of tablets (at 10:00 A.M.). IPS at 20 mg significantly decreased temperature and increased cortisol levels. Although IPS increased ACTH levels at 20 mg, this effect was variable and not significant. IPS did not affect prolactin levels nor did it have any behavioral effects. Although 20 mg IPS decreased blood pressure and pulse rate in one subject, overall it had no significant effect on these parameters. IPS at 20 mg PO appears a useful probe to test 5HT1a function when temperature and cortisol are used as response variables. These results replicate earlier studies on the effect of IPS in healthy human subjects.

Adrenocorticotropic Hormone↗
PubMed1993

Serotonin function and treatment response to clozapine in schizophrenic patients.

OBJECTIVE: Clozapine is the only compound proven to be effective in the 20% of schizophrenic patients refractory to treatment with conventional neuroleptics. Although its mechanism of action has not been elucidated, clozapine appears, in contrast to most conventional neuroleptics, to be a potent serotonin (5-HT) antagonist. This study hypothesized that 5-HT function is increased in patients who benefit from clozapine treatment relative to patients who fail to improve on it. METHOD: The 5-HT receptor agonist m-chlorophenylpiperazine (MCPP) was used as a probe to examine 5-HT function. MCPP (0.35 mg/kg p.o.) was administered in a placebo-controlled design after a 3-week drug-free period to 19 schizophrenic patients. ACTH, prolactin, body temperature, behavior, and MCPP blood level were measured. Patients were then treated with a conventional neuroleptic, and, having failed to respond to it, were treated with clozapine for 5 weeks (up to 600 mg/day). RESULTS: Patients who responded to clozapine had significantly higher ACTH responses to MCPP during the drug-free state than the patients who failed to benefit from clozapine. Moreover, the degree of improvement with clozapine, particularly the improvement in psychotic symptoms, was strongly correlated with the magnitude of MCPP-induced ACTH release. Other MCPP-induced responses and MCPP blood level were similar for the two groups and did not correlate with the degree of symptomatic improvement with clozapine. CONCLUSIONS: Results of this study suggest that MCPP-induced ACTH release, and by inference 5-HT receptor function, may be increased in patients who benefit from treatment with clozapine relative to patients who fail to improve on this drug.

Adrenocorticotropic Hormone↗
PubMed1993

A reliability study of SLEDAI: a disease activity index for systemic lupus erythematosus.

SLEDAI, a disease activity index for systemic lupus erythematosus (SLE) has been validated against other such indices and its reliability has been shown by specialists in SLE. To assess its reliability among less experienced clinicians, we conducted a reliability study with 3 rheumatology trainees and 9 patients with SLE according to a Latin square design. SLEDAI easily distinguished between patients (p = 0.0009), and physician variability was not statistically significant (p = 0.27). Inter and intraobserver agreement were 78.7 and 98.0%, respectively. SLEDAI was thus shown to be a reliable instrument among less experienced observers for the assessment of disease activity in SLE.

Education, Medical, Graduate↗
PubMed1992

Effect of m-chlorophenylpiperazine on plasma homovanillic acid concentrations in healthy subjects.

In view of the abundant anatomical and functional interactions between serotonin and dopamine systems, this study examined the effect of the serotonin agonist, m-chlorophenylpiperazine (mCPP) on plasma concentrations of the dopamine metabolite, homovanillic acid. Plasma prolactin levels, body temperature, and mCPP blood level were also measured. mCPP (0.35 mg/kg) and placebo were administered orally to 10 healthy men in a randomized double-blind design. Variables were measured for 210 min after administration of capsules. mCPP raised prolactin and temperature as compared to placebo, but did not affect plasma homovanillic acid concentrations. Results suggest that mCPP does not alter dopamine function.

Administration, Oral↗
PubMed1992

Nocturnal growth hormone secretion in schizophrenic patients and healthy subjects.

Plasma growth hormone concentrations were measured at hourly intervals between 10 p.m. and 8 a.m. the next morning in 15 drug-free chronic schizophrenic male inpatients and 14 healthy males. Growth hormone secretion was significantly lower in the patients as compared with the controls. Growth hormone release peaked around 1 a.m. in the controls, but a growth hormone peak was absent in the patient group. Increased dopamine activity, increased serotonin activity, or both could explain the absence of a nocturnal growth hormone surge in the schizophrenic patients.

Adult↗
PubMed1992

Serotonin function in schizophrenia: effects of meta-chlorophenylpiperazine in schizophrenic patients and healthy subjects.

This study examined serotonin (5-hydroxytryptamine; 5HT) receptor responsivity in 22 chronic schizophrenic patients and 17 healthy control subjects. The 5HT agonist meta-chlorophenylpiperazine (MCPP) was used as a probe of serotonergic function. MCPP (0.35 mg/kg) or placebo was administered orally after a 3-week drug-free period in a randomized double-blind design. Hormonal (adrenocorticotropic hormone and prolactin), temperature, and behavioral responses and MCPP blood levels were assessed for 210 minutes after administration of the capsules. The schizophrenic patients had blunted temperature responses compared with those of the healthy control subjects: MCPP raised body temperature in the control subjects, but not in the patients. Behavioral responses also differed in the two groups: MCPP increased the total Brief Psychiatric Rating Scale (BPRS) score in the control subjects and tended to decrease it in the patients. In patients, MCPP decreased the BPRS psychosis subscore. Hormonal responses did not differ significantly in the two groups. These findings suggest that further exploration of 5HT function in schizophrenia is warranted.

Adrenocorticotropic Hormone↗
PubMed1992

Agitation and postdexamethasone cortisol levels in Alzheimer's disease.

The clinical correlates of hypothalamic-pituitary-adrenal (HPA) functioning were examined in 29 patients with probable Alzheimer's disease. The 8:00 a.m. postdexamethasone cortisol levels of these patients were highly correlated with higher agitation scores but not with the degree of depressed mood or memory impairment. The possible neural basis for the association between hypercortisolism and behavioral disturbance in Alzheimer's disease warrants further exploration and replication.

Alzheimer Disease↗
PubMed1992

[An analysis of the organization, profile of the clientele and pathologies managed in the urology division of the Public Assistance-Hospital of Paris. A 15-day cross-sectional survey of 10 services].

A cross-sectional study was carried out in ten urology departments over a two-week period. Three categories of data were collected concerning socio-economic status and epidemiological profiles and management of the patients. The results are presented with comparative analysis of performance of the clinics, and the epidemiological data are analysed with reference to the inpatient case mix.

Aged↗
PubMed1991

Growth hormone responses to intravenous clonidine challenge correlate with behavioral irritability in psychiatric patients and healthy volunteers.

To explore the relationship between central noradrenergic receptor responsivity and indices of impulsive aggression, growth hormone responses to infusions with the alpha 2-adrenergic receptor agonist clonidine (GH[CLON]) and responses on the Buss-Durkee Hostility Inventory (BDHI) were examined in healthy male volunteers and male patients with major affective or personality disorder. GH[CLON] values were found to correlate significantly with the BDHI "Irritability" subscale in all subjects, but especially in healthy volunteer and personality disorder patients. GH[CLON] values did not correlate with the BDHI "Assault" subscale. These results suggest a role for central alpha 2-adrenergic receptor responsivity in the personality trait characterized by behavioral irritability, but not overt assaultiveness, in humans.

Adult↗
PubMed1990

Different modulation of flash responses of fast and slow relay cells by aversive electrical brain stimulation.

Electrical activity of single neurons of the dorsal lateral geniculate nucleus of rats was recorded from stereotactically fixed animals. The neurons were classified as fast or slow ones, according to their response latency to electrical stimulation of the chiasma opticum. After this, the responses to diffuse flashes, to aversive electrical stimulation of the brain (ESB) and to a combination of both, brain stimulation immediately followed by a flash, were recorded. One week prior to testing, bipolar nichrom electrodes had been implanted into the tectotegmental region for the ESB, and their effectiveness was tested behaviorally. Out of 78 neurons 56 fast and 22 slow ones were found. Fast neurons have a significantly higher background activity than slow neurons. Both classes show a modulation of flash evoked responses by the ESB, although the ESB has nearly no effect on the spontaneous discharge frequency in any of the neurons. The influence on the flash response differs according to the cell class: the class of fast neurons is predominantly facilitated up to 1100 ms after the flash application, whereas the class of slow neurons is inhibited during this period. Later on (up to 2260 ms after flash) fast cells show no clear net effect, and slow cells were still slightly inhibited.

Animals↗
PubMed1990

Buspirone challenge: preliminary evidence for a role for central 5-HT1a receptor function in impulsive aggressive behavior in humans.

The prolactin (PRL) response to challenge with buspirone hydrochloride, a serotonin1a (5-HT1a) receptor agonist, was examined in 5 healthy male volunteers and in 10 healthy male and female patients with primary DSM-III personality disorder. In healthy volunteers, pretreatment with the nonselective 5-HT receptor antagonist, metergoline (4 mg p.o.) completely suppressed the maximal PRL response to buspirone challenge. Pretreatment with the nonselective beta-adrenergic/5-HT1-like antagonist, pindolol suppressed the maximal PRL response to buspirone challenge depending upon dose (i.e., between 49 to 90% suppression at best dose). In personality disorder patients, PRL responses to buspirone challenge correlated inversely with self-assessed "irritability" (r = -.76, n = 10, p less than .01). These data suggest that the PRL response to buspirone challenge reflects the responsivity of 5-HT1a receptors in the limbic-hypothalamus in humans and that reduced sensitivity of these receptors is associated with an important component of impulsive aggressive behaviors in personality disorder patients.

Adult↗