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Biomedical subjects

P Franchimont

Publications and source records attributed to P Franchimont.

At least 343 records · Page 19Linked to original sources
PubMed1981

Lack of clinical and physiological relationship between gastrin and calcitonin in man.

The clinical and physiological relevance of the relationship between gastrin and calcitonin has been investigated in normal subjects and in patients suffering from gastritis or duodenal ulcer. Basal plasma levels of calcitonin are increased in these patients but there is no significant relationship between calcitonin and gastrin levels. Acute pentagastrin injection in normal male subjects increased significantly (P less than 0.05) plasma calcitonin levels whereas lower doses of pentagastrin which are known to stimulate gastric secretion are without effect on calcitonin levels. Moreover, stimulation of gastrin secretion by a protein test meal and by intragastric administration of a calcium chloride solution is not followed by any significant increase of plasma calcitonin levels. These results suggest that the stimulation of calcitonin secretion by gastrin and its synthetic analogue pentagastrin is a pharmacological rather than a physiological phenomenon.

Adult↗
PubMed1981

Evidence for a hypothalamic site of action of inhibin to suppress FSH release.

To determine if inhibin has a hypothalamic site of action to suppress FSH release, highly purified inhibin preparations from the rete testis fluid (RTF) of rams were injected into adult male rats which had been orchidectomized (ORDX) 24 hours earlier. Third ventricular (3rd V) injection of a potent inhibin fraction (RTF 38-I) significantly depressed plasma FSH concentrations, without influencing LH, 4-10 h after treatment. A less active preparation of inhibin (RTF 38-II) at the same dose had no effect. A higher dose of another less potent fraction (RTF 1A) significantly reduced FSH 2-6 h following 3rd V administration, accompanied by slight but significant decrements in LH at 2 and 4 only. To determine responsiveness of the pituitary, luteinizing hormone-releasing hormone (LHRH) was injected intravenously at 6 h. It induced similar elevations of FSH and LH in inhibin- and saline-treated groups. Systemic administration of RTF 38-II at a dose 2.5-fold higher than the dose effective centrally failed to modify either FSH or LH levels up to 6 h. These results provide evidence that inhibin from the male can preferentially suppress FSH release by a CNS site of action in addition to its well-known pituitary site of action.

Animals↗
PubMed1981

Comparison of acute effects of 1.25- and 24.25-dihydroxy-vitamin D3 in normal subjects.

Effects of small iv doses of 1.25-dihydroxy- and 24.25-dihydroxy-vitamin D3 (a microgram) were studied in 10 normal subjects. Injection of 1.25 (OH)2D3 was associated with small but significant increases in plasma calcium and phosphate but plasma levels of immunoreactive parathyroid hormone (iPTH) and calcitonin (iCT) did not change. The administration of 24.25 (OH)2D3 was associated with comparable decreases in plasma calcium and a small and transient decrease in plasma iPTH. Plasma levels of iCT did not change. 24.25 (OH)2D3 also significantly increased glomerular filtration rate and decreased the urinary excretion of noradrenaline, in contrast to 1.25 (OH)2D3 which had no effect on these variables. The rapid infusion of calcium significantly decreased levels of iPTH. We conclude that small doses of 1.25 (OH)2D3 and 24.25 (OH)2D3 have little, if any, direct effect on the secretion of PTH and CT in man.

24,25-Dihydroxyvitamin D 3↗
PubMed1981

Regulation of inhibin production by bovine ovarian cells in vitro.

The regulation of ovarian inhibin production was investigated using a rat pituitary cell culture system as a bioassay for inhibin activity. Bovine follicular granulosa cells produced inhibin in vitro provided that the culture medium contained serum. The stimulatory factor(s) present in serum is unlikely to be gonadotrophins, because bovie LH and/or FSH failed to stimulate inhibin production when added to medium devoid of serum. Luteinization of granulosa cells in culture was accompanied by a reduction in their inhibin production and an inverse relationship existed between inhibin and progesterone production by granulosa cells. Bovine corpus luteum cells in culture failed to produce detectable amounts of inhibin. Androgens stimulated granulosa cell inhibin production with testosterone and 5 alpha-dihydrotestosterone being more potent than androstenedione. The androgens did not stimulate inhibin production by luteal cells. Progesterone inhibited granulosa cell inhibin production but oestrogens had no effect. Measurement of steroids and inhibin in fluid from individual follicles indicated that as follicle size increased, concentrations of oestradiol-17 beta increased, testosterone and inhibin decreased and progesterone remained unchanged. The stimulatory effect of testosterone on inhibin production in vitro together with the parallel changes in follicular fluid concentrations of testosterone and inhibin suggest that ovarian inhibin production in vivo may be controlled, at least in part, through androgens modifying granulosa cell inhibin production. The inhibitory effect of progesterone on granulosa cell inhibin production may be more important in regulating ovarian inhibin production at the time of granulosa cell luteinization and CL formation. The stimulatory effect of androgens on granulosa cell inhibin production might also be a means by which androgens promote follicular atresia.

Animals↗
PubMed1981

[Intracellular mechanism for the action of inhibin on the secretion of the follicular-stimulating hormone and luteinizing hormone induced by LH-RH in vitro].

The FSH secretion-inhibiting action of inhibin in vitro under basal conditions and also in the presence of LH-RH is suppressed by the addition of MIX, a phosphodiesterase inhibitor. In the presence of LH-RH, inhibin reduces significantly the intracellular level of cAMP in isolated pituitary cells. In contrast, the simultaneous addition of MIX and inhibin raises the cAMP level, and this stimulation is comparable to the increase observed when MIX is added alone. These observations suggest that one mode of action of inhibin could be mediated by a reduction in cAMP within the pituitary gonadotropic cell.

1-Methyl-3-isobutylxanthine↗
PubMed1981

[Radioimmunoassay for type II amino-terminal procollagen peptide. Technical note].

We have studied the immunoreactivity of human sera and synovial fluids in a radioimmunoassay which utilizes an anti-bovine procollagen type III antiserum and the bovine type III procollagen peptide as standard and tracer. We have noticed a complete cross reaction between bovine col 1-3 and human synovial fluid, which thus contains substance (s) having the same antigenic determinant (s) as col 1-3. On the contrary, we have demonstrated non parallelism between col 1-3 and human serum, whether the serum was obtained from normal subjects or patients suffering from various diseases. These results suggest that immunoreactive substances related to col 1-3 and detected in sera are at least partially different from those detected in synovial fluids.

Animals↗
PubMed1981

[Gonadocrinin-like activity of the peritoneal fluid during the menstrual cycle in the normal female].

Peritoneal fluid formation and composition is under the dependence of the ovarian function. Collection of these fluids was performed by laparoscopy in normal cycling women. After absorption of the steroids, they were tested on monolayer pituitary cell cultures in order to study the influence on gonadotrophin release. LH secretion was stimulated through cell the menstrual cycle without any cycling variations. FSH secretion was also increased, excepted in the immediate post-ovulation period. Thus the Peritoneal fluid contains, as follicular fluid, substances with gonadocrinin- and inhibin-like activity. Gonadocrinin activity was not correlated with estradiol and progesterone levels in serum and peritoneal fluid.

Animals↗
PubMed1981

[Intermittent liberation of gonadoliberin (GnRH) by the rat hypothalamus in vitro].

Hypothalamus were dissected from suprachiasmatic area to mamillary bodies in 50 days old male rats. These fragments were subsequently removed and incubated for 3 hours at 37 degrees C in Dulbecco Modified Eagle's medium supplemented with glucose and containing calcium (1.25 mM) and potassium (5.81 mM). Incubation medium was changed every 5 or 15 minutes and immediately collected at 4 degrees C for highly specific radioimmunoassay of GnRH using R 42 antiserum of Nett and Niswender. In these conditions, mean +/- 1 SD release of immunoreactive GnRH per 1 hour was 199 +/- 68 pg (n = 4) and 135 +/- 38 pg (n = 6) in medium collected every 5 and 15 minutes respectively. Furthermore GnRH release was found to be episodic, 3 to 5 peaks being observed during a period of 2 hours. It is concluded that, following deafferentation and isolation in vitro, mature hypothalamus remains capable of releasing GnRH in a spontaneous periodic manner, suggesting that this particular feature of neuroendocrine maturation can be initiated in the hypothalamus itself.

Animals↗