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Biomedical subjects

S Guillemant

Publications and source records attributed to S Guillemant.

72 records · Page 4Linked to original sources
PubMedDate not supplied

Biologic, histologic and densitometric effects of oral risedronate on bone in patients with multiple myeloma.

Recent studies have shown that treatment with bisphosphonates could be effective against the myelomatous skeletal deterioration. However, the mechanisms of action of these drugs in multiple myeloma (MM) have been poorly studied. In the present study, 11 patients with MM and bone lesions were treated orally with 30 mg/day of risedronate for 6 months, and monitored for 6 additional months. Mean serum calcium decreased from day 4, with a concomitant increase in circulating levels of PTH (1-84) and 1,25-(OH)2D. These parameters reached their nadir on day 7 and returned to baseline value during the treatment period. Markers of bone resorption, pyridinoline and deoxypyridinoline decreased from day 7; they were at 50% and 78% of their basal value at the end of treatment and follow-up periods, respectively. A significant reduction of estimates of bone formation (serum alkaline phosphatase and osteoclacin) appeared at month 3 and persisted for the remainder of the 9-month period. Histomorphometric analysis showed a significant reduction of activation frequency, number of osteoclasts and erosion depth. Bone turnover was high at baseline, and normal after treatment, without mineralisation defects. Mean wall thickness was not different before and after treatment. Spinal bone mineral density measured by dual energy X-ray absorptiometry increased (5.3%) at the end of treatment. We conclude that oral risedronate in multiple myeloma induces a noticeable and rapid inhibition of bone resorption.

Absorptiometry, Photon↗
PubMedDate not supplied

Acute effects of oral calcium load on parathyroid function and on bone resorption in young men.

AIM: The aim of the present study was to check whether a calcium oral load was able to inhibit bone resorption as assessed by urinary excretion of a new bone marker, type 1 collagen cross-linked C-telopeptide (CrossLaps(TM)), in healthy young male adults. METHODS: Twenty healthy young male adults (age 22 +/- 2 years) were studied. In one series of assays, an oral calcium load of 1 g of elemental calcium as calcium citrate dissolved in 200 ml of low-calcium water was ingested, while in another series of assays the subjects ingested 200 ml of water alone. Blood samples were collected before and 1, 2, 3 and 4 h after the intake of calcium. Urine was collected at 2-hour intervals, i.e. before and for 4 h after the intake of calcium. Serum ionized calcium, phosphate and intact parathormone (iPTH) were measured at each time point. Urinary calcium, phosphate, creatinine and CrossLaps (as a ratio to creatinine) were measured in each urine sample. RESULTS: Calcium intake was associated with very significant (ANOVA, p < 0.001) increases in serum ionized calcium and decreases in PTH. After calcium intake, measurements of urinary CrossLaps showed a progressive statistically significant (ANOVA, p < 0.001) decrease (-20% at 2 h and -55% at 4 h), whereas after ingestion of water, the changes were modest and not statistically significant. CONCLUSIONS: The present results show that bone resorption as assessed by urinary excretion of CrossLaps can be significantly suppressed by the ingestion of a 1-gram calcium load and attest that calcium supplementation has an acute effect on bone metabolism.

Administration, Oral↗
PubMedDate not supplied

[Effects of phosphate therapy on parathyroid gland reactivity].

The effects of a single oral dose of phosphate (780 mg of elemental phosphorus as 100 drops of Phosphoneurol 120 from DOMS-Adrian Laboratories) on parathyroid function and on calcium and phosphate metabolism were studied in 10 young adults. The parathyroid response was checked by measurement of PTH 1-84 and of nephrogenous cAMP before and after a 10 days therapy by phosphate (780 mg of elemental phosphorus twice daily). Before treatment a 16 per cent increase in PTH 1-84 (p less than 0.05) and a 34 per cent increase in nephrogenous cAMP (p less than 0.02) was obtained. After treatment the increases were respectively 34 per cent for PTH 1-84 (p less than 0.001) and 67 per cent for nephrogenous cAMP (p less than 0.001). The responses in PTH 1-84 and in nephrogenous cAMP were significantly (p less than 0.05 and p less than 0.01) higher after than before treatment by phosphate.

Adult↗
PubMedDate not supplied

[Simultaneous radiocompetitive assay for 25 hydroxyvitamin D and 24, 25 dihydroxyvitamin D in human serum (author's transl)].

A specific competitive protein binding assay for 25 hydroxy-vitamin D and 24, 25 dihydroxyvitamin D in human serum has been developed. It includes a chromatographic step on a Sephadex LH 20 column to specifically separate the metabolites. The average value was for 25 hydroxyvitamin D 11.9 +/- 6.6 Ng/ml (mean +/- SD) and for 24, 25 dihydroxyvitamin D 6.85 +/- 3.29 ng/ml in ten normal subjects sampled in autumn. In hepatic insufficiencies the mean level of 25 hydroxyvitamin D was lower and the mean level of 24, 25 dihydroxyvitamin D was higher than in normal subjects. In patients with renal insufficiency the 25 hydroxyvitamin D levels were normal and the 24, 25 dihydroxyvitamin D levels were low but not suppressed. The two sterols were also determined in some patients with idiopathic hypercalciuria.

Binding, Competitive↗
PubMedDate not supplied

Clinical chronopharmacology of ACTH 1-17. I. Effects on plasma cortisol and urinary 17-hydroxycorticosteroids.

The aim of the investigation was to study the effects of ACTH 1-17 on both plasma cortisol and urinary 17-OHCS in health adult young males with regard to the time (clock hours) at which this polypeptide was injected. Eight healthy adults (males from 18-30 years) volunteered for the study. They were synchronized with a diurnal activity from 0700 to 0000 and a nocturnal rest. Each week, during 6 consecutive weeks (January 19 to February 25, 1980), a 3-day test was performed on Saturday, Sunday and Monday. On Sundays 3 control-tests and 3 ACTH-tests were programmed during which either saline or 100 micrograms ACTH 1-17 were injected i.m. at respectively 0700, 1400 and 2100. During each 3 day-test (72 h) the urinary excretion of 17-OHCS was determined every 4 h at fixed clock hours. In addition, on Sundays, venous blood was sampled prior to control or ACTH injections at respectively 0700, 1400, and 2100 and 20, 40, 60, 90, 120, 150 and 180 min thereafter. Plasma cortisol (radioimmunoassay) was determined in samples thus collected. Both conventional and cosinor methods were used for statistical analyses. A strong and statistically significant rise of plasma cortisol was observed after all of the ACTH 1-17 injections. The obtained mean response curves were observed after all of the ACTH 1-17 injections. The obtained mean response curves were similar in form and parallel. The highest plasma cortisol curve corresponded to ACTH injected at 0700, the lowest to ACTH injected at 2100. The curve corresponding to ACTH injected at 1400 went in-between. The 24-h urinary excretion of 17-OHCS after ACTH 1-17 was approximately 4 times greater than the control value when injected at 0700, approximately 3 times greater than control when injected at 1400 and only twice greater than control when injected at 2100. In terms of changes in plasma cortisol and 17-OHCS the greatest best benefit of ACTH 1-17 is achieved when this polypeptide is injected at 0700, rather than at 1400 or 2100 in diurnally active subjects.

17-Hydroxycorticosteroids↗
PubMedDate not supplied

Clinical chronopharmacology of ACTH 1-17. II. Effects on plasma testosterone, plasma aldosterone, plasma and urinary electrolytes (K, Na, Ca and Mg).

The aim of the investigation was to study the effects of ACTH 1-17 on plasma testosterone, plasma aldosterone as well as on both plasma and urinary electrolytes (K, Na, Mg and Ca) in healthy young adult males with regard to the time (clock hours) at which this polypeptide was injected. Eight healthy adults (males from 28 to 30 years) volunteered for the study. The were synchronized with a diurnal activity from 0700 to midnight and a nocturnal rest. Each week, during 6 consecutive weeks (January 19 to February 25, 1980) a 3-day test was performed on Saturday, Sunday and Monday. On Sundays 3 control-tests and the 3 ACTH-tests were programmed during which either saline or 100 microgram ACTH 1-17 were injected i.m. at respectively 0700, 1400 and 2100. During each 3 day-test period (72 h) the urinary excretion of K, Na, Mg and Ca was determined every 4 h at fixed clock hours. In addition, on Sundays, venous blood was sampled prior to control or ACTH injections at respectively 0700, 1400 and 2100 and 20, 40, 60, 90, 120, 150 and 180 min thereafter. Plasma testosterone, aldosterone (radioimmunoassays) K, Na (flame photometry), Mg and Ca (photocolorimetric methods) were determined in the collected samples. Both conventional and cosinor methods were used for statistical analyses. The injection of ACTH at 0700 was followed by a clear and statistically significant rise of plasma testosterone. No change with regard to control occurred when ACTH was injected at either 1400 or at 2100. A statistically significant rise of plasma aldosterone was observed after each of the ACTH injections. However, the highest plasma aldosterone level was reached when ACTH was administered at 1400 and the lowest level at 2100. ACTH-induced changes in plasma electrolytes were either nil (for Na and Ca) or small (for K and Mg). A more or less important increase of urinary K occurred after the ACTH injection at each of the 3 considered times. The highest values of excreted K occurred after the injection of ACTH at 0700, without shift of the acrophase. In contrast, injections of ACTH at 1400 and 2100 induced a dramatic alteration of the K rhythms. ACTH induced an important fall in the Na urinary excretion. This fall was the greatest when ACTH was injected at 1400. Na rhythm alterations also occurred, particularly after ACTH injections at 2100. However, this effect was less pronounced after ACTH injection at 0700 than at other considered time points. The urinary amount of excreted Ca did not seem to be affected by ACTH. Rhythm alterations occurred after ACTH injections at 1400 and 2100. Peaks of plasma testosterone, plasma aldosterone as well as plasma cortisol (reported in a previous paper) resulting from ACTH stimulation coincided in time with the acrophase of the physiological circadian rhythm in plasma levels of these hormones...

Adolescent↗
PubMedDate not supplied

[Circadian and circannual rhythms in results of functional tests in endocrinology].

Basic aspects of the temporal organization of endocrine circadian systems are summarized. Emphasis is given to the concept of chronesthesy (rythmic changes in the susceptibility of target biosystems) and that of chronokinetics (rhythmic changes in the metabolic fate of hormones and other agents). These complementary concepts are needed for the understanding of circadian and/or circannual changes in results of a test. The following substances used either for stimulation or suppression tests were investigated: metyrapone, ACTH, corticosteroids (e.g. dexamethasone), TRH, HCG, glucose, insulin. The subject's synchronization, the time (clock hour in the 24 hours scale, month in the yearly scale) appears to be at least as important as conventional factors such as subject's sex, age, nutritional state when performing a test and interpreting the results.

Adaptation, Physiological↗