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Biomedical subjects

C Gharib

Publications and source records attributed to C Gharib.

At least 181 records · Page 10Linked to original sources
PubMed1985

[Oral glucose tolerance tests in man during a 150-day space flight (Salyut 7-Soyuz T9)].

This study was conducted on the pilot specialist of the Salyut 7-Soyuz T9 complex during a 150 days space flight. Glucose tolerance tests were made 3 days before flight, on days 60 and 88 during flight and on days 25 and 55 after flight. The study confirms the decrease of fasting plasma glucose observed during the 3 Skylab missions and demonstrates blunted glucose tolerance curves. The changes were not found during ground based studies using bed rest to simulate weightlessness state. The origin of this abnormality is discussed.

Adult↗
PubMed1985

[Effect of physical training by swimming on the arterial pressure, plasma and hypothalamo-post-hypophyseal vasopressin in genetically hypertensive rats of the Lyon strain].

The effect of a 5-week swimming training on systolic blood pressure (PAS) and vasopressin (AVP) and Neurophysins (NpT) concentration in the blood and content in the pituitary and the hypothalamus was studied in Lyon genetically hypertensive rats [LH] and in their controls: the normotensive [LN] and low blood pressure [LL] rats belonging to the 28th generation. Nine female rats of each group were trained 5 days a week for 5 weeks, starting with 2 h a day, with a 15 min increase every day, up to 6 h a day. The PAS was measured using an indirect plethysmographic technique one time a week during the whole training session. At the end of the training, the rats were decapitated. AVP and NpT were measured in blood, pituitary and hypothalamus, by radioimmunoassay (RIA). Hematocrit as well as plasma Na+, K+, protein and osmotic content were also measured. Results show that the training did not affect any of the studied parameters: mainly, there was no decrease in PAS or plasma AVP level in the hypertensive rats compared to the normotensive ones. The only difference was a lower AVP content in the pituitary of LH rats compared to LN (p less than 0.01), which is difficult to interpret. Our results shed doubt on the efficiency of a swimming training on the evolution of hypertension in the Lyon rat model.

Animals↗
PubMed1985

[Circulatory and hormonal changes induced by microgravity].

The absence (or decrease) of the hydrostatic pressure during space flights (microgravity state) or simulations of weightlessness (by immersion, bed rest or head-down tilt) result in a body fluid shift and an engorgement of the central circulation where mechanoreceptors involved in plasma volume regulation are located. Their activation induces the initial (first hours) hormonal response with a decrease in plasma vasopressin, renin and aldosterone and probably an increase in a natriuretic factor (Gauer reflex). Prolonged exposure to microgravity leads to more complex and often hypothetical responses: cardiovascular deconditioning, modifications in secretion and circadian rhythms of above cited hormones. After 24 years of studies on approximately 200 astronauts our knowledge of cardiovascular and hormonal adaptation to space flight is still at the beginning.

Adaptation, Physiological↗
PubMed1983

Effect of PEEP ventilation on renal function, plasma renin, aldosterone, neurophysins and urinary ADH, and prostaglandins.

To explore the main factors which could be involved in the fluid retention induced by continuous positive pressure ventilation (CPPV), hemodynamics, renal, and hormonal parameters were measured in seven intensive care patients during three consecutive 60-min periods; one of intermittent positive pressure ventilation (IPPV), one of CPPV (PEEP 10 cmH2O), and finally one of IPPV. During CPPV, a 15% decrease in cardiac output was observed, without alteration in arterial pressure or right atrial transmural pressure. In addition, decreases were observed in urinary output by 34%, glomerular filtration rate by 19%, renal blood flow by 32%, sodium excretion by 33%, and potassium excretion by 26%. There was no change in the fractional excretion of sodium and free water. Institution of PEEP also led to a significant increase in plasma renin activity, plasma aldosterone, and urinary antidiuretic hormone, without significant variation in plasma neurophysins and urinary prostaglandins E and F alpha. All of the changes that occurred during CPPV were reversed when PEEP was withdrawn. It is concluded that the short-term antidiuretic effect of PEEP is mainly due to a hemodynamic impairment of renal function. The water- and sodium-retaining hormonal systems also are stimulated and could participate in the fluid retention during more prolonged respiratory support with PEEP.

Adolescent↗
PubMed1981

Plasma vasopressin, renin activity, and aldosterone: effect of exercise and training.

The influence of endurance-training on hematocrit, plasma vasopressin, renin activity, and aldosterone changes at rest and at the end of an exercise performed until exhaustion at a given and constant relative work-load (87% of maximal oxygen uptake) has been studied in four untrained subjects submitted to a 5-month training. At the end of this period, maximal oxygen uptake increased of 15.2% (p less than 0.01). Hematocrit at rest slightly rose after training, and if exercise constantly induced increases in hematocrit before (p less than 0.001) and after training (p less than 0.005), the per cent increase after training was lower than before (p less than 0.05). Comparison between the importance of weight loss and hematocrit variation showed that when untrained subjects become trained the variation of hematocrit after exercise becomes smaller while weight loss is more important (p less than 0.01). Plasma renin activity (PRA), aldosterone (Aldo) and vasopressin (AVP) levels, compared to control values, displayed a significant increase after exercise before as well as after training. Control values remained unchanged after training for aldosterone and AVP, but were significantly lower (p less than 0.05) for PRA. This latter observation could be explained by the change in blood volume induced by exercise.

Adult↗
PubMed1981

Urinary excretion of immunoreactive vasopressin in prepubertal children. Lack of correlation with urinary excretion of immunoreactive neurophysins.

The excretion of immunoreactive vasopressin (AVP) and neurophysins was determined in 24 h urine samples from 62 normal healthy children of various ages. Five groups of children were selected: group I (n = 7, aged 2 to 3 years), group II (n = 13, aged 3 to 5 years), group III (n = 16, aged 5 to 7 years), group IV (n = 16, aged 7 to 9 years), group V (n = 10, aged 9 to 11 years). The method used for urine AVP determination consisted of an extraction using a procedure slightly modified from that of Miller and Moses [14], coupled to a radioimmunoassay. The following urinary AVP excretions were obtained: group I mean: 70.8 ng/m2/24 h range: 51-150 ng, group II mean: 54.1 ng/m2/24 h range: 17-113.6 ng, group III mean: 55.2 ng/m2/24 h range: 18-106 ng, group IV mean: 39.9 ng/m2/24 h range: 11.7-77.9 ng, group V mean: 39.4 ng/m2/24 h range: 25.8-64 ng. The excretion of AVP was significantly correlated to the daily urinary osmolality (P less than 0.001) whether expressed in ng/24 h (r = 0.41) o rin ng/m2/24 h (r = 0.4.7). Neurophysins excretion ranging between 7 and 1,278 ng/24H is too variable to allow interpretation.

Age Factors↗
PubMed1981

Radioimmunoassay of arginine vasopressin, oxytocin and arginine vasotocin-like material in the human pineal gland.

Specific radioimmunoassays (RIAs) have been developed for arginine-vasopressin (AVP), oxytocin (OT), and arginine-vasotocin (AVT): they can detect 2.5 pg, 5 pg and 1 pg of hormone respectively. The three antisera employed in the RIAs in the present study all had a specificity that discriminated between the three neuropeptides and thus allowed their accurate measurement in each of 157 human pineal glands. Immunoreactive AVP was found to have a mean concentration of 306.4/+-27.6 (SE) pg/gland in the 1389 pineals where it was at level higher than the detection limit. Immunoreactive OT was determined as 386.3/+-42.1 pg/gland in the 110 pineals where it was measurable, and the mean apparent immunoreactive AVT content was 44.6/+-3.6 pg/gland in the 110 pineals where it was found at detectable levels. Cross-reactivity with AVP or OT cannot account for the immunoreactive peptide content of human adult pineal glands was demonstrated as a function of: (1) sex, (2) time of death, (3) cause of death, (4) age (18 to 85 yr old) or (5) delay between death and gland removal over the range of 4 to 48 hr. While the presence of AVP and OT is not surprising, indications of an immunoreactive AVT may in fact reflect a peptide which is closely related to AVT and cross-reacts in the AVT RIA.

Antibody Specificity↗
PubMed1981

[Plasma renin activity (PRA) and aldosterone (PA) during submaximal exercise. Effect of training (author's transl)].

The effect of training on PRA, PA, hematocrit and weight loss was studied at rest and following an exercise performed until exhaustion. Two groups of subjects were used, the first, a group of 4 young well trained men (88.6% +/- 7.7 V02 max) and the second a group of 4 young untrained men (77.5% +/- 7 V02 max). PRA and PA displayed highly significant increases after exercise in both groups, but PRA resting values were lower in the well trained subjects (p less than 0.05). PRA values were also lower in the latter group after exercise, but the difference in this case was not significant. Further, the variation of hematocrit was less (p less than 0.05) and the weight loss greater in the well trained subjects. In an additional experiment, the same parameters were studied in four subjects submitted to a five month training programme (87% V02 max). Though resting values for PA remained unchanged after training, PRA resting values and PRA post exercise values were significantly lower. A comparison between the magnitude of weight loss and hematocrit variation showed that when untrained subjects became trained, the variation of hematocrit was smaller (p less than 0.05) while weight loss was larger (p less than 0.01). These observations could be explained in terms of the change in blood volume, and/or a decrease in sympathetic nervous activity induced by training.

Adult↗
PubMed1980

Plasma AVP, neurophysin, renin activity, and aldosterone during submaximal exercise performed until exhaustion in trained and untrained men.

The effect of intense muscular work (80% of maximal oxygen uptake) on responses of plasma hormones involved in electrolyte and water balance were measured in 14 male subjects. They were divided into three groups according to their maximal oxygen uptake and the duration of exercise performed until exhaustion: well trained subjects (group I), trained subjects (group II), and untrained subjects (group III). Pulmonary gas exchange, heart rate, rectal and skin temperature, and weight loss were measured as well as hematocrit and plasma and urine sodium and potassium concentrations. Rectal temperature increased significantly in all subjects after exhaustion. The variation of hematocrit was smallest and the weight loss greatest in the well-trained subjects. Plasma aldosterone, renin activity (PRA), vasopressin (AVP), and neurophysin (Np) displayed highly significant increases after exercise in all three groups: PRA was increased 4.5 times (p < 0.01), aldosterone 13 times (p < 0.05), Np 2.6 times (p pe 0.05), and AVP 4.8 times (p < 0.05). Nevertheless, there was no correlation between the changes in PRA and those in plasma aldosterone, nor between aldosterone and plasma sodium or potassium. At the urinary level, the only striking observation was that free water clearance tends to become positive after exercise. Our results provide evidence that this kind of exercise produces a highly significant increase in plasma levels of the hormones involved in electrolyte and water balance. They also indicate that it is among the well-trained subjects that sweat loss is highest though the hematocrit increase is the smallest; this suggests that water is shifted more efficiently from the extravascular compartment.

Adult↗
PubMed1980

[Urinary elimination of oxytocin and vasopressin measured by radioimmunoassay in different phases of the menstrual cycle in women].

Urinary arginine-vasopressin (AVP) and oxytocin (OT) excretion were measured by radioimmunoassay and studied in 3 normally cycling women. No difference for AVP and OT excretion was found between the different phases of the menstrual cycle. But in one subject with a typical pre-menstrual syndrom (weight gain of 1.5 kg), a significant statistical difference was found in AVP excretion (p less than 0.05) between the pre-ovulatory (25.3 +/- 3.08 ng/24 h) and the post-ovulatory (39.45 +/- 5.59 ng/24 h) phase. The well known stimulatory effect of estrogen as judged from plasma studies on neurohypophyseal hormones was thus difficult to demonstrate in urine. These results could be explained by the fact that the kidney destroys both AVP and OT, but OT at a higher rate than AVP.

Female↗
PubMed1979

[Inappropriate secretion of antiduiuretic hormone during acute leukaemia treated with vincristine. Two cases (author's transl)].

One the basis of two special typical cases, the authors detail the symptoms and signs and consider the physiopathology of inappropriate secretion of antidiuretic hormone related to vincristine. Urinary ADH was measured in both cases. ADH levels could be studied on ten consecutive occasions during the course of one of the cases (obs. n 1). Eleven similar cases have been found in the literature. ADH was measured in only three of them. Methods of treatment are considered, with particular emphasis on the role of demeclocycline.

Child↗
PubMed1979

[Radioimmunoassay of ADH in human urine (author's transl)].

A simple efficient procedure for extracting and concentrating arginine-8-vasopressin (AVP) from urine has been coupled with a specific and sensitive radioimmunoassay in order to measure antidiuretic hormone (ADH) excretion in normal humans under various physiological stimuli. Antisera have been raised in rabbits injected with lysine-vasopressin (LVP) or AVP coupled with bovine serum albumin. The antiserum selected for the assay which inhibits the antidiuresis induced in the rat by AVP is used at a final dilution of 1 : 50,000 and possesses a high association constant of 1 x 10(11) 1.mol-1. The limit of detection of the RIA system is 0.5 micronUI/ml of urine (1.25 pg). Urinary ADH has been extracted from urine by Miller and Moses method. Mean recovery of added vasopressin averaged 90.2% +/- 11 (SD) and assay of serial dilutions of such extracts showed that they behave in the assay system in the same way as synthetic AVP standards. Moreover comparison of the results obtained by the RIA to those given by the biological method using the ethanol anesthetized rat showed excellent correlation (r = 0.9 p less than 0.001). Under ad libitum fluid and food intake, mean daily urinary excretion of AVP (uncorrected for recovery) determined in 22 subjects was found to be 30.58 +/- 11.64 mU/h with no significant difference between men and women. In response to an oral waterload ADH became undetectable at the peak of diuresis. Following a 16 hr fluid deprivation, ADH rose moderately. A significant correlation has been found between urine osmolality and AVP excretion rate.

Adult↗
PubMed1978

[Radioimmunoassay of urinary oxytocin in man].

A radioimmunoassay (RIA) for oxytocin (OT) in urine is described. 125I-OT was prepared, and antibodies were raised in rabbits against OT coupled to bovine serumalbumine. This allowed us to set up of RIA for OT which limit of detection is 1.25 pg/tube (0.6 microU). The use of an extraction procedure using CG50 Amberlite is essential. The recovery after extraction reaches 70.5%. pH 5 is the optimum pH were urine samples must be stored. The superposition of the elution peak of endogenous OT on that of exogenous hormone is an argument in favour of the validity of such an extraction procedure. Daily urinary excretion of OT reaches 9.58 mU +/- 3.48 in 18 healthy young men.

Adult↗