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Biomedical subjects

J Sebaoun

Publications and source records attributed to J Sebaoun.

At least 37 records · Page 2Linked to original sources
PubMed1986

Differential effects of passive immunization with somatostatin antiserum on adenohypophysial hormone secretions in starved rats.

The role of somatostatin (SRIF) on adenohypophysial hormone secretion in starved rats was reassessed by passive immunization. Because of the absence of pulsatile GH secretion in starved rats, the effects of the injection of SRIF antiserum on GH levels can be clearly demonstrated. To determine whether starvation modifies the sensitivity of the adenohypophysis to SRIF, we measured 125I-labelled iodo-N-Tyr-SRIF binding. There was no difference in the dissociation constant (Kd) nor in the maximal binding capacity (Bmax) in fed (n = 15) and starved (n = 15) animals (Kd = 0.38 +/- 0.09 (S.E.M.) and 0.45 +/- 0.09 nmol; Bmax = 204 +/- 39 and 205 +/- 30 fmol/mg protein respectively). Administration of SRIF antiserum resulted in a dose-dependent increase in plasma concentrations of GH, TSH and prolactin. The minimal effective dose of SRIF antiserum was 50 microliters for GH, 100 microliters TSH and 200 microliter for prolactin. Our results show that: starvation does not modify adenohypophysial SRIF-binding sites, in starved male rats endogenous SRIF exerts a negative control on prolactin secretion in vivo and sensitivity to endogenous SRIF seems to be different for each hypophysial cell type.

Animals↗
PubMed1986

[Microalbuminuria in diabetics with moderate hypertension].

The relation between hypertension and diabetic nephropathy is complex. Nephropathy is probably involved in the elevated blood pressure found in diabetic patients. In maturity onset diabetes, patients may also have hypertension which is associated with obesity or essential hypertension. It has been suggested that in both types of diabetes, hypertension enhances the development of diabetic nephropathy. Moreover, an aggressive antihypertensive treatment seems able to reduce rate of decline in kidney function in insulin-dependent diabetic patients with patent nephropathy. In this work, creatinine clearance and microalbuminuria in 20 diabetic patients (mostly with maturity-onset-diabetes) with known moderate and effectively treated hypertension were therefore measured and the results were compared with those for 18 normotensive diabetic patients and 22 controls. Duration of diabetes was from one to 26 years (mean: 11 years) and duration of hypertension was from one to 35 years (mean: 10 years). Patients and controls had normal serum creatinine and proteinuria below 0.1 g/l. Microalbuminuria was measured by immunonephelometric assay using specific antiserum (sensitivity = 1.5 mg/l; intra and interassay coefficients: 6.5% and 8% respectively). The highest value was observed in hypertensive diabetic patients with retinopathy (group 1). But hypertensive patients without retinopathy (group 2) and normotensive patients also had significantly increased microalbuminuria. In group 1, microalbuminuria was significantly higher than in group 2. The creatinine clearance was reduced in groups 1 and 2 versus normotensive diabetics, but hypertensive patients were older.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Evidence of direct thyroid-stimulating action of thyrotropin-releasing hormone by perifusion of rat thyroid fragments.

The possibility that TRH has a direct thyroid-stimulating action has never been reported. A number of studies have shown a rise in serum concentrations of thyroid hormone after stimulation with TRH, without a rise in TSH secretion. This has led us to test TRH with rat thyroid fragment perifusion. Significant T4 release was observed for TRH concentrations as low as 1.7 X 10(-11) M. A dose-response curve was determined. The response was immediate, reaching a peak after the sixth minute and continuing for 15 min after the stimulation had ceased. This kinetic pattern is different from the one observed with TSH and with theophylline and suggests that a different mechanism may be involved. TRH seems to be capable of directly stimulating both the secretion of the pituitary hormone (TSH) and the corresponding peripheral gland, like LHRH, which also acts directly on the Leydig cells of the testis.

Animals↗
PubMed1985

[Rheumatological manifestations of adrenal insufficiencies].

Muscular, articular and periarticular symptoms were reviewed in 19 patients with adrenal failure and compared with previously published data. Symptoms are variable and non-specific; muscular cramps and periarticular calcification were common. Hypercalcaemia was uncommon but its incidence was probably underestimated. Calcification of the ear cartilage was rare but characteristic.

Adrenal Insufficiency↗
PubMed1985

[Abnormalities of 24 hour (Holter) ECG monitoring in diabetics: involvement of cardiac autonomic neuropathy and/or insulin therapy].

In order to detect evidence of cardiac autonomic neuropathy, 24-hour continuous electrocardiographic monitoring was carried out on fifty-one diabetic patients (thirty-one IDD, twenty NIDD) and twenty-two healthy controls taking no treatment which could alter the heart rate. In the diabetic patients the minimum 24-hour heart-rate and the mean sleeping heart rate were significantly higher, and the maximum 24-hour heart rate and the ratio [(maximum-minimum heart rates)/minimum heart rate] were significantly lower. Evidence in one diabetic of cardiac autonomic neuropathy was found only as the difference (maximum-minimum heart rates). This index was found to be below 38/min (mean-2 SD of the controls) in seven diabetics, but only one of the nine diabetics with signs of autonomic neuropathy had this abnormal index. The mean values for the minimum and the mean sleeping heart rates were high in the IDD with or without signs of peripheral neuropathy and without signs of autonomic neuropathy but were not high in IDD with signs of autonomic neuropathy. These findings suggest the presence of cardiac autonomic neuropathy in diabetics. However, the possibility of insulin-induced tachycardia should be considered this tachycardia is probably related to stimulation of the sympathetic nervous system, which would explain the absence of abnormalities in IDD with autonomic neuropathy.

Adult↗
PubMed1984

[Value of the perifusion of fragments of rat thyroid for the dynamic study of thyroid secretion under TSH and theophylline].

With the technique of rat thyroid fragment perifusion the kinetics of T4 response to various stimuli can be studied with precision. The response is rapid and brief with theophylline and TSH, which activate membrane adenylcyclase; with the optimal concentrations, however, it is prolonged because only these concentrations can induce the secretion of a more slowly releasable pool of T4.

Animals↗
PubMed1984

Compared effect of propranolol and acebutolol on serum thyroid hormones' levels in euthyroid and hyperthyroid patients: a randomized study.

An open randomized study involving 57 subjects, 40 euthyroid and 17 hyperthyreotic, was undertaken to compare the effect of two beta-adrenergic blocking drugs, propranolol (120 mg/day) and acebutolol (600 mg/day), on the thyroid hormones serum level. In hyperthyreotic as well as in euthyroid subjects, propranolol evoked a fall in T3, an increase in reverse T3 and therefore a decrease in the T3/rT3 ratio. Acebutolol caused a decrease in T3 and in the T3/rT3 ratio only in euthyroid subjects. The only significant variation in the hyperthyroid acebutolol treated group was a decrease in reverse T3, perhaps spontaneous. TBG and TSH concentrations remained stable under treatment in all the groups. The relation of these effects with the existence of a membrane stabilizing activity displayed by propranolol as well as by acebutolol is discussed.

Acebutolol↗
PubMed1983

Evidence of a thyrotropin-releasing hormone-dependent increase in plasma thyrotropin during refeeding of starved rats.

After 3 days of starvation, refeeding with carbohydrate (CHO) leads to a rapid increase in plasma T4 and T3, suggesting increased TSH secretion. The aim of the present study was to describe the time course of plasma TSH changes during refeeding with CHO and fat. Repetitive blood samples were obtained from freely moving animals by indwelling jugular venous catheters. Refeeding was performed on the fourth day of starvation at either 1100 or 1900 h, and blood was sampled during the preceding hour and during the following 3 h. In control experiments, blood was sampled over 4 h without refeeding. Refeeding with CHO and fat induced a significant increase in plasma TSH in the first hour. This increase could be abolished by a previous injection of an anti-TRH serum, while normal rabbit serum was without effect. Plasma corticosterone, measured hourly, also showed a tendency to increase with refeeding. It is concluded that refeeding of starved rats represents a reproducible stimulus for TSH secretion.

Animals↗
PubMed1983

[Biological rhythms of thyrotropin secretion].

The rhythmic pattern of TSH secretion is now well-established and is characterized by a circadian (24 h) periodicity with a pre-sleep acrophase which is modulated by endogenous oscillators and environmental synchronisers. Among external synchronisers, the sleep-waking cycle has been extensively studied and sleep onset appears to have a negative influence on the nycthemeral TSH peak. Nutritional status may affect the TSH rhythmicity since a short term starvation induces a shift in the acrophase time. Major neurotransmitter involved in the TSH rhythms are serotonine which could be responsible for the TSH nadir. By contrast dopamine is not directly implicated in the circadian pattern of TSH secretion. TRH, the main neuropeptide controlling the thyrotrope cell, certainly has a major role in the mediation of the TSH rhythmicity. The involvement of somatostatine is less clear but as assumed for dopamine, its negative influence on TSH secretion would be stronger at the time of TSH peak than at the time of nadir. The major inhibitory effect of thyroid hormones on TSH secretion and release is evident on mean serum TSH levels but does not seem responsible for serum circadian variations. Likewise, the TSH rhythm is present in both sex and influence of estrogens and androgens would only be to modulate the mean serum TSH level. Finally the physiological influence of glucocorticoids on TSH secretion has not been clearly demonstrated.

Adult↗
PubMed1982

[Isolated ACTH deficiency associated with leukoneutropenia (author's transl)].

The paper describes the case of a 38 year's old alcoholic patient. The investigation of his severe asthenia led to the discovery of an isolated ACTH deficiency: plasma cortisol was less than 1 microgram 100 ml reactivable by tetracosa-peptide beta 1-24. Plasma ACTH was low and remained so after LVD and metyrapone. Persistent leuconeutropenia without myelogram and agar cultures abnormalities was noted. Etiocholanolone test was negative and epinephrine induced a significant rise in blood leucocytes. The authors review the mechanisms of corticoid action on leucopoiesis. After 10 months corticoid treatment, leuconeutropenia improved but was still present suggesting an other underlying mechanism than cortisol insufficiency per se.

Adrenal Insufficiency↗
PubMed1979

[Echocardiographic study of hyperthyroidism based on 9 cases of Basedow's disease (author's transl)].

An echocardiographic study of nine patients with graves' disease before and after treatment demonstrates changes in myocardial contractility predominantly in the posterior wall and, to a lesser extent, in the intraventricular septum. The parameters most significantly changed were: velocity of posterior wall thickening and posterior left ventricular wall relaxation rate. There was not in any of the cases neither evidence of cardiac insufficiency nor a diminution of VCF. All of the modifications regressed rapidly with the euthyroid state. These results affirm the functional character of this disease dismissing the existence of an autonome cardiomyopathy of thyroid etiology.

Adult↗
PubMed1979

[Wolff-Parkinson-White during a basedowienne thyrotoxicose (author's transl)].

The case reported here consisted of an association of a Wolff-Parkinson-White syndrome (WPW) with thyrotoxicosis, with simultaneous recovery by thyroidectomy; this lead the authors to review 13 previous cases in the literature. The physiopathologic discussion emphasized several points: 1) the specific action of thyroid hormones, 2) the hypothesis of the possible existence of inapparent pathways of pre-exitation in most subjects and 3) a simple practical attitude to adopt in all Wolff-Parkinson-White cases especially when rapid.

Animals↗
PubMed1979

[Critical study of the treatment of Grave's disease (author's transl)].

202 cases of Grave's disease were reviewed; among the 81 patients submitted to medical treatment, 53,1 p. 100 of patients failed to respond; 10 p. 100 relapsed and 35,9 p. 100 are euthyroid. The factors favouring a treatment failure were: age below thirty, severity of thyrotoxicosis, big enlargement of thyroid gland, duration of treatment shorter than 12 months. Relapses are more frequent after two years of medical treatment. Subtotal thyroidectomy was performed in 82 patients: 9,5 p. 100 relapsed, permanent hypothyroidism developed in 30,5 p. 100 and 50 p. 100 were euthyroid. The factors favouring post-operative hypothyroidism are estimated weight of the thyroid remnant, the moderate size of goiter and perhaps a six to twelve months preoperative medical treatment. 39 patients had I 131 therapy: among them, 24 p. 100 relapsed, 25,7 p. 100 had permanent hypothyroidism and 50,3 p. 100 are euthyroid.

Adolescent↗
PubMed1975

Antibodies against myoid thymic cells and striated muscle, and monoclonal gammapathy in myasthenia gravis.

The serum of a patient with myasthenia gravis contained a particularly high titer of antistriated muscle antibodies, as well as a monoclonal IgM Kappa immunoglobulin. The antibody activity was only associated with IgG fractions and not with the monoclonal IgM, when these immunoglobulins were separated by chromatography. The association of these two immunological disorders is discussed.

Aged↗