摘要:

In vitrotime course studies of progesterone and protein synthesis by hamster preovulatory follicles (harvested prior to the proestrous gonadotropin surge) were done. LH appears to stimulate progesterone synthesis in 2 phases. The first phase lasts 0 to 4 or 5 hr and is not inhibited by either puromycin or cycloheximide. The second phase (apparent by 4-5 hr) is distinquished from the first phase by its inhibition by puromycin and cycloheximide, and by the differential dose response of dibutryl cyclic AMP on the respective 2 phases. Incorporation of a3H-labelled mixture of amino acids into protein is not seen in LH-stimulated follicles in 2 hr incubations but is apparent by 4 hr. The LH-stimulated protein synthesis is inhibited by puromycin. The results indicate that although LH stimulates both phases of progesterone synthesis, the mechanisms may be different for each phase.

ISSN:0743-5800    

DOI:10.3109/07435808509035420

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

Normotensive recumbent subjects exhibit an early (11 p.m.) nocturnal increase in plasma dopamine, norepinephrine and epinephrine sulfates. In individual patients, this peak value is followed by a smaller nocturnal peak of catecholamine sulfates, while free catecholamine levels change in a direction opposite to catecholamine sulfates. This reciprocity of changes cannot however be demonstrated in the whole group. The origin of the nocturnal peaks of catecholamine sulfates is unknown. It may be due to a nocturnal decrease of the renal clearance of catecholamine sulfates, an increased generation of sulfates for reasons other than an increase in the free catecholamine substrate, or possibly a release of catecholamine sulfates from the brain.

ISSN:0743-5800    

DOI:10.3109/07435808509035421

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

The effects of changing the concentrations of calcium (Ca2+) and inorganic phosphate (Pi) on45Ca release from prelabeled fetal rat bones caused by parathyroid hormone (PTH), 25-hydroxyvitamin D3(25-OH-D3) and 1, 25-dihydroxyvitamin D3(1,25-(OH)2-D3) were tested,in vitro.Increasing total (Ca2+) from 1.25 mM to 2.5 mM caused a significant increase in bone resorption caused by suòmaximal concentrations of these materials. Further increase in total (Ca2+) to 3.5 mM abolished this potentiating effect of bone resorption.Increasing the (Pi) from 1 mM to 2-3 mM caused significant inhibition of bone resorption caused by these resorbing materials. In addition, a (Pi) of 3 mM caused significant inhibition of higher concentrations of PTH and 25-OH-D3. (Pi) of 2 and 3 mM also caused significant inhibition of 45Ca release from control bones.It is concluded that a moderate increase in medium (Ca2+) mimics the effect of these bone resorbing materials on bone. Phosphate appears to be a direct inhibitor of bone resorption. Therefore, changing the (Ca2+) and (Pi) in the medium can affect the bone resorbing effect of vitamin D3metabolites, similar to their effect on PTH.

ISSN:0743-5800    

DOI:10.3109/07435808509035422

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

Ovine corticotropin releasing factor (CRF) was administered to six normal men and the plasma ACTH and cortisol responses compared with those following the same dose of CRF (200ug) plus the opiate receptor blocker naloxone (20mg). The addition of naloxone was associated with a significant increase in plasma ACTH, cortisol and aldosterone responses. No change was observed in peripheral plasma levels of epinephrine, norepinephrine, arginine vasopressin, angiotensin II or renin activity in response to CRF plus naloxone. It is concluded that endogenous opioid peptides may inhibit the ACTH response to CRF. However the addition of naloxone does not increase the ACTH response to CRF sufficiently to constitute a useful test of pituitary function.

ISSN:0743-5800    

DOI:10.3109/07435808509035423

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

The effects of fatty acyl substituents and head groups of phospholipids on the liposomal cholesterol transfer to steroid-free cytochrome P450scc were examined as a model system for ACTH-enhanced availability of cholesterol to the cytochrome in the inner membrane of adrenal cortex mitochondria. It was implicated that using a variety of saturated and unsaturated phospholipids fatty acyl groups play an important role in the transfer reaction.

ISSN:0743-5800    

DOI:10.3109/07435808509035424

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

We have examined the effects of parathyroid hormone (PTH) and cortisol on the production of prostaglandins, particularly PGE2, by neonatal rat calvaria cultured in a chemically-defined medium. Although there was considerable variability, calvaria produced large amounts of PGE2in control cultures, reaching medium concentrations of 40 to 200 nM. PGE2release was partially inhibited by cortisol at 10 nM and markedly inhibited at 100 nM. Bovine 1–34 synthetic PTH produced an increase in PGE2concentration which was most striking in the presence of a low concentration of cortisol (10 nM). The medium also contained large amounts of 6-keto PGE1a, the metabolite of prostacyclin, which showed similar changes in response to PTH and cortisol. Thromboxane B2concentrations were low and unaffected by these hormones. 1,25-dihydroxyvitamin D did not increase medium PGE2concentration. Since PGE2is a potent stimulator of bone resorption and formation, some of the effects of PTH as well as cortisol may be mediated by their ability to alter PGE2production in skeletal tissue.

ISSN:0743-5800    

DOI:10.3109/07435808509035425

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

Four hundredüg of synthetic thyrotropin releasing hormone (TRH) were given intravenously to 4 normal men and 4 normal women, and four weeks later, 1000üg of TRH were administered intravenously to 4 of the 8 individuals and oxytocin (OT) was measured in plasma on both occasions. Following injection of either dose of TRH, OT did not change significantly from baseline.Likewise, synthetic gonadotropin releasing hormone (GnRH), 100üg, administered intravenously to 6 normal men did not alter the levels of OT from baseline. Synthetic OT, 300 mU/minute, administered 30 minutes before and for 90 minutes after injection of GnRH, was without effect on the GnRH-induced rise of luteinizing hormone (LH) or follicle stimulating hormone (FSH) in normal men.We conclude that continuous infusion of OT in pharmacologic concentrations does not alter the pituitary release of LH or FSH in response to GnRH in humans. TRH and GnRH given intravenously do not alter basal levels of OT in the plasma of humans, thus a physiologic role for GnRH or TRH in the neuroendocrine control of OT secretion in humans is unlikely.

ISSN:0743-5800    

DOI:10.3109/07435808509035426

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

Synthetic rat and ovine CRF were tested in anin vitroisolated pancreatic islet system for their ability to influence insulin and glucagon release. Acute exposure of islets to both rat and ovine CRF resulted in a significant increase in glucagon release but only over a narrow range of concentration (50–200 pg/ml). Neither peptide had a significant effect on insulin release. Our results raise the possibility that release of glucagon may be stimulated by CRF as part of the overall response to stress.

ISSN:0743-5800    

DOI:10.3109/07435808509035427

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

Upon interaction with phospholipid vesicles containing phosphatidylserine, isolated rat adipocytes demonstrate an inhibition of insulin-stimulated hexose uptake. In order to elucidate the mechanism of this effect, adipocytes were treated with agents, alone or in combination with vesicles, which affected the insulinsensítive response at the receptor and post-receptor level. The effect of vesicles at a maximal inhibitory concentration proved to be non-additive with dexamethasone, suggesting that vesicles may act in a manner similar to this agent. In contrast, fat cells treated with vesicles and N-ethylmaleimide (NEM) or trypsin at submaximally effective concentrations demonstrate a partially additive inhibition of insulin-stimulated 2-deoxyglucose uptake. Vesicle treatment of adipocytes before stimulation with agents which mimic insulin, such as Con A and H2O2, demonstrates the same effects as insulin with respect to hexose uptake. These results support the contention that vesicles inhibit insulin action at least partially at the post-receptor level, and may directly interfere with the hexose transport site.

ISSN:0743-5800    

DOI:10.3109/07435808509035428

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

There is substantial documentation of the presence of insulin resistance in many patients with chronic renal failure (1). Circulating levels of insulin are increased and there is a delayed and reduced glucose response to the administration of insulin (2). Peripheral target tissues of uremic patients and rats are resistant to insulin action (3–6). There is reduced uptake of glucose by skeletal muscle as shown by forearm perfusion (5) and the euglycemic clamp (4) in uremic humans and by hindlimb perfusion in uremic rats (7).

ISSN:0743-5800    

DOI:10.3109/07435808509035429

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor