Biomedical subjects

J Charrier

Publications and source records attributed to J Charrier.

At least 37 records · Page 2Linked to original sources

PubMed1987

[Oligo-arthritis associated with type IV hyperlipoproteinemia].

A case of chronic, corticosteroid-responsive arthritis affecting particularly one ankle in a patient with type IV hyperlipoproteinaemia is reported. After gout or inflammatory rheumatism of another nature had been excluded, and following synovial fluid examination and synovial membrane biopsy, a diagnosis of type IV hyperlipoproteinaemia rheumatism was made. At electron microscopy, the synovial membrane showed numerous large spumous cells and a peculiar appearance of the capillary vessels.

Ankle Joint↗

PubMed1987

Effects of hypothalamic hormones (GRF, TRH, somatostatin) and insulin-like growth factor I on growth hormone secretion from prepubertal male lamb pituitary cultures.

We have examined the regulation of GH secretion from monolayer cultures of prepubertal male lamb anterior pituitary cells. Growth hormone-releasing factor (GRF 1-44) stimulated GH release in a dose-related manner: the maximal effective dose was 10(-10) M, which caused a 500% increase in basal GH secretion, while the half-maximal effect was reached with a dose of 2.5 x 10(-11) M (ED50). Thyrotropin-releasing hormone (TRH) also elicited a dose-dependent stimulation of GH secretion, although it was approximately 1000 times less potent than GRF. GRF and TRH did not have additive or synergistic effects on GH secretion. Somatostatin (SRIF) at a concentration of 10(-7) M maximally inhibited basal GH release to 40% of that of the control; the ED50 was 2.0 x 10(-9) M. Moreover, 10(-7) M SRIF blocked the stimulation of GH secretion induced by 10(-8) M GRF. However, when the cells were incubated with these two peptides at an identical concentration (10(-8) M), GH secretion was stimulated significantly above control values. When added at the same concentration (10(-7) M, TRH ans SRIF nullified their respective effects. A dose of 100 ng/ml of synthetic IGF-I was without effect on basal GH release, but significantly decreased 10(-9) M GRF-induced stimulation of GH secretion. these data indicate that in prepubertal male lambs: the stimulatory effect of GRF is predominant over the inhibitory effect of SRIF, somatostatin inhibits TRH stimulation of GH secretion in vitro, and IGF-I may control GH secretion by modulating GRF effects at the pituitary level.

Animals↗

PubMed1987

Characteristics of growth hormone response to the administration of growth hormone-releasing hormone (GRF) in the lamb.

Human growth hormone releasing hormone (GRF 1-44 or GRF 1-29) was administered to lambs at two different physiological stages (suckling: 5-6 week-old and weaned: 14-15 week-old) when growth hormone (GH) secretory patterns were different: suckling lambs exhibited flat basal GH profiles (5-10 ng/ml) while the weaned lambs had frequent spontaneous episodes of GH release (15-65 ng/ml). The iv injection of GRF evoked an immediate release of GH. In each case, plasma GH levels reached a maximum 1-4 min after the injection. The secretory spike was multiphasic and lasted 30-60 min. Administration of GRF (0.1 microgram/kg) in weaned lambs induced GH pulses with an amplitude comparable to that of endogenous peaks. The induction of a GH peak occurred even when a spontaneous peak immediately preceded the GRF injection. Also, spontaneous peaks were observed during the hour following a GRF-induced GH peak. In suckling lambs, GRF injected intravenously as a single bolus in a range of 0.01 to 0.5 microgram/kg (2 to 100 pmoles/kg) stimulated GH release in a dose-dependent manner. Chronic administration of GRF (0.75 nmole GRF 1-44 or GRF 1-29 per kg twice daily for 21 days) in newborn lambs increased significantly (p less than 0.001) the acute response to GRF during the course of the treatment. GH response to GRF 1-44 and GRF 1-29 was the same. These data show that lambs are highly responsive to GRF action during both suckling and weaning and suggest that there is no in vivo desensitization of the pituitary gland after acute or chronic GRF administration.

Animals↗

PubMed1987

Effects of TRH and GRF administration on GH, TSH, T4 and T3 secretion in the lamb.

The effects of various amounts of thyrotropin-releasing hormone (TRH) injected subcutaneously or intravenously (alone or in combination with growth hormone-releasing factor: GRF 1-44) on growth hormone (GH), thyroid-stimulating hormone (TSH), thyroxine (T4) and triiodothyronine (T3) were studied in the plasma of 2-week, 2-month and 3-month old lambs. After subcutaneous TRH administration, increases in plasma TSH, T4 and T3 levels were equivalent, whatever the amount of TRH used (1,2,5 or 10 micrograms/kg). These responses lasted longer after 5 and 10 micrograms/kg. After intravenous TRH administration in 2-week old lambs, the maximal increase in plasma TSH levels occurred after the injection of 0.25 microgram/kg. However, plasma T4 and T3 responses were not different, whatever the amount used. As previously, the amount of TRH affected the duration of these responses more than the magnitude of the pituitary-thyroid axis response. Whatever the injection route, amount used or animal age, TRH alone did not increase GH secretion in lambs. However, it slightly delayed the GH response to GRF. GRF did not affect the response of TSH and T4 to TRH; however it could inhibit T3 increase. In conclusion, in contrast to results obtained in calves by Hodate et al. (1985), TRH did not enhance GH secretion in lambs but, as expected, induced sharp increases in plasma thyroid hormone levels. Its classification as a "growth factor" is therefore questionable, at least in lambs.

Animals↗

PubMed1987

Secretory profiles and production rate of growth hormone in ruminant lambs.

Secretory profiles and production rates of growth hormone (GH) were determined in 6 ruminant lambs during winter. The mean GH concentrations (3.78 +/- 2.17 ng/ml) calculated were based upon blood sampling obtained every 3 min using a withdrawal pump. Body clearance (0.162 +/- 0.031 1/h/kg) was calculated from bolus intravenous oGH administration. The data were analysed by non-linear regression analysis; a bicompartmental model was selected to describe the data. production rate was 14.6 +/- 7.98 micrograms/kg/24 h. It has been emphasized that the experimental design used gave an accurate estimate of GH production rate.

Animals↗

PubMed1986

The Brattleboro rat: normal growth hormone secretion, decreased hepatic growth hormone receptors and low plasma somatomedin activity.

Three-month-old male Brattleboro rats with hereditary diabetes insipidus (DI) present a growth defect; Brattleboro rats were studied together with age-matched Long-Evans (LE) rats. Pituitary growth hormone (GH) content was comparable in both groups of rats. Pulsatile GH release and mean 6 h GH plasma levels did not appear significantly different in chronically catheterized DI and control animals. In parallel with the growth defect, the plasma somatomedin bioactivity was significantly lower in DI than in LE rats. The specific binding of [125I]iodo-hGH to liver microsomal membranes of DI rats was 59.7% that of controls. The number of the GH binding sites rather than the affinity of the binding was decreased. The specific binding of [125I]iodo-insulin was oppositely affected by the DI state: it was 1.5 times higher in liver membranes of DI rats than in membranes of LE rats. These findings make a non-specific effect of the DI state on liver membrane proteins unlikely. The Brattleboro rats present a growth failure without reduction of their GH secretion. The decreased number of the hepatic GH receptors and the subsequent low plasma somatomedin activity could explain the growth retardation of the DI rats.

Animals↗

PubMed1985

Bioassay of growth-stimulating activity of serum: comparison of lymphocyte and cartilage assays in normal and growth hormone-deficient children.

The somatomedin and/or growth-stimulating activity of serum from hypopituitary children and short children with normal growth hormone (GH) response to stimulation tests were studied using different bioassays: thymidine incorporation into human activated lymphocytes; sulfate incorporation into chick embryo cartilage; and simultaneous thymidine uptake into the same cartilages. The results showed that lymphocyte assay is highly sensitive to small amounts of serum and is GH-dependent in children with low GH secretion. On the contrary, the cartilage assays need higher serum concentration and their GH-dependence appears only in subjects with normal or low-normal GH secretion. The lack of correlation between the results of the three bioassays suggests that they measure both somatomedins and different serum factors involved in the regulation of growth.

Adolescent↗

PubMed1985

Growth-promoting activity of serum throughout pregnancy and at delivery: evaluation by three different bioassays.

Somatomedin evolution has been studied by employing three different bioassays in 181 pregnant women from the 7th week of gestation to delivery and in 18 women during the course of labor. In 105 additional mothers of full-term or pre-term neonates a significant increase of a serum growth-promoting activity (thymidine activity) was observed at delivery, as compared to nonpregnant controls, with a progressive return to normal levels in the post-partum period. Different results were found according to the assay method used, suggesting the multiplicity of growth factors and specific adaptations related to the stages of pregnancy.

Biological Assay↗

PubMed1980

Somatomedin-A bioactivity in rabbit serum after hypophysectomy.

Hall's bioassay was used to determine the somatomedin (Sm) activity pattern after hypophysectomy in young (40 days) and adult (180 days) rabbits. In the young animals, Sm activity decreased a little, but the serum remained slightly active. The serum of the older rabbits progressively lost its sulphation activity and inhibited SO4 uptake after 2 weeks following hypophysectomy. The inhibitory activity could not be destroyed by heating. Concomitantly, the same serum continued to stimulate thymidine uptake. From the present results on bioactivity, it appeared that Sm generation was only partially pituitary-dependent, that the pituitary might control inhibitor synthesis, and that the SO4 and thymidine factors were separate entities, each having its own inhibitor(s).

Age Factors↗

PubMed1980

Development of growth hormone receptors in rabbit and lamb liver after hypophysectomy.

The prolactin receptors of rat liver are pituitary-dependent, and previous studies have shown that prolactin itself plays a role in inducing and maintaining their presence. This study tried to determine if hepatic growth hormone (GH) receptors are comparably dependent on the pituitary. Young 47-day and older 116-day old rabbits were either hypophysectomized (H) or sham-operated (S). Hypophysectomy completely arrested the growth of the older rabbits but only reduced it by 50 p. 100 in the young ones. After 21 days, the specific binding (sb) of 125I-labelled human GH (hGH) to liver membranes was measured in H and S animals. The sb of hGH in H rabbits compared to S animals (older, young) was 14.9 p. 100 in older H rabbits and 45.5 p. 100 in young H animals. Similar studies in lambs showed that the sb of hGH in H lambs (compared to S animals) was 23.9 p. 100. When some H lambs were treated with 1 mg/kg of oGH or bGH 3 times per week, the sb of hGH was significantly increased to 56.1 p. 100 of the S levels. All changes in sb reflected changes in receptor number, as shown by the dose response binding curves. This study demonstrates that hepatic GH receptors in both the rabbit and the lamb are pituitary-dependent. The level in rabbits is correlated with the growth rate. Since GH receptor levels were partially restored in GH-treated lambs, it is possible that GH plays a role in inducing its own receptors.

Animals↗

PubMed1980

Somatomedin-A (Sm-A) bioactivity in serum and amniotic fluid as related to weight in the fetal pig.

Serum and amniotic fluid Sm-A bioactivity has been assayed in the fetal pig using a double labelling technique. 3H-thymidine activity was always higher in fetuses and lower in sows than 35S activity. 35SO4 uptake was not stimulated or was inhibited in about 30 p. 100 of the fetal sera. 3H-thymidine uptake was stimulated in all of them. There was a significant correlation (P less than 0.001) between fetal weight and serum Sm, as judged with both 35SO4 and 3H-thymidine. No correlation was found between fetal weight and amniotic fluid Sm, between amniotic fluid and serum Sm or between 35SO4 and 3H activities. It is concluded that the latter activities were due to two or more factors instead of only one.

Amniotic Fluid↗

PubMed1980