Role of the placenta in the control of the ante-partum surge of prolactin in the rat

A nocturnal surge of prolactin secretion occurs in the dark period preceding parturition in the rat. The aim of this study was to examine the role of the placenta in the control of this prolactin surge. Plasma prolactin and progesterone were measured by radioimmunoassay in serial blood samples collected after surgical removal of conceptuses during late pregnancy, and after intracerebroventricular (i.c.v.) injection of placental lactogen (PL) before the prolactin surge. In intact control animals, prolactin secretion remained low until a nocturnal surge of secretion occurred in the dark period preceding parturition, peaking at 269 +/- 51 (S.E.M.) micrograms/l at 03.00 h on day 21. Progesterone levels fell from greater than 200 nmol/l on day 19 to less than 40 nmol/l by 12.00 h on day 20 of pregnancy. PL levels during late pregnancy were modified by partial or complete removal of conceptuses at 10.00 h on day 19 of pregnancy. Removal of all but one or two conceptuses did not change the normal pattern of prolactin or progesterone secretion. Removal of all conceptuses, however, induced a large nocturnal surge of prolactin secretion, peaking at 211.7 +/- 78 micrograms/l at 03.00 h on day 20, 24 h earlier than the surge in intact animals. Progesterone levels after removal of all conceptuses fell to less than 40 nmol/l by 23.00 h on day 19, approximately 12 h before the decline in intact animals. Maintenance of increased progesterone levels after conceptus removal using silicone tubing implants significantly (P less than 0.05) reduced the peak of the premature prolactin surge to 79.7 +/- 18 micrograms/l at 05.00 h on day 20.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prevention of the manifestation of diabetes in the elderly in the presymptomatic stage

Diabetes Mellitus is thought as the presymptomatic stage to cause various vascular diseases. From the point of view that diabetes is already a disease, this paper discusses the prevention of the manifestation of diabetes in the elderly. STOP-NIDDM study demonstrated that acarbose, an alpha-glucosidase inhibitor, reduced the onset of diabetes in impaired glucose tolerance (IGT) subjects by 24%. On the other hand, the Diabetes Prevention Program (DPP) study for IGT subjects revealed that intensive life style intervention prevented diabetes most powerfully by 58% and metformin treatment also reduced by 31%. Furthermore, HOPE, LIFE, and SCOPE studies against hypertension showed that ACI or ARB reduced diabetes by 20-32%, and the WOSCOT study that pravastatin, a HMG-CoA reductase inhibitor, reduced diabetes by 30%. These accumulated results suggest that the most suitable strategy to prevent diabetes in the elderly is intensive life style intervention, and in cases incapable of exercise and diet therapy, acarbose or metformin are recommended for IGT. When associated with hypertension and/or hyperlipidemia, the subjects have to receive ACI or ARB and statins to prevent diabetes.     

On the Role of the Septal Area in the Development of Doca-Salt Hypertension in the Rat

The extensive destruction of forebrain noradrenergic nerve terminals by the intraventricular injection of 250 μg of 6-hydroxy-dopamine prevents the subsequent development of DOCA-salt experimental hypertension in rats while the lesser destruction of noradrenergic nerve terminals produced by 90 μg of 6-hydroxydopa does not. The greatest difference in brain part noradrenaline levels between these two neurotoxins was in the septal area where noradrenaline was less than 15% of controls after 6-hydroxydopamine but was the same as controls after 6-hydroxydopa. The non-specific destruction of the lateral septal area by radiofrequency lesions prevented the subsequent development of DOCA-salt hypertension. The relatively selective destruction of catecholamine nerve terminals in the lateral septal area by the injection of 1 μg 6-hydroxydopamine in 1 μl vehicle also prevented the development of DOCA-salt hypertension. These data suggest that the lateral septal area may be the location of the forebrain catecholaminergic neural activity that is necessary for the development of DOCA-salt experimental hypertension in rats.     

美托洛乐治疗老年人高血压

疾病 高血压病。目的 评估美托洛尔治疗高血压的短期疗效和安全性，病人年龄在50—75岁。     

Role of insulin in the regulation of the tubular reabsorption of glucose in the kidneys

Glucose tubular transport in the kidneys in changes of insulin concentration in the blood was studied in acute and chronic experiments on dogs. Maximum glucose reabsorption in the kidneys was shown to remain unchanged in the stimulation of insulin secretion or depletion of insular function (alloxan diabetes). Neither did the administration of insulin into the renal artery at doses of 0.02-0.04 U/min for 30 min. influence glucose reabsorption which rose during hormone infusion at doses of 0.4-0.5 U/min only.     

On the possible role of the liver in the galactopoietic action of prolactin in the rat

The possibility that the liver contributes to the galactopoietic effects of PRL was assessed in lactating rats in which endogenous PRL secretion was suppressed by injections of bromocriptine. Pup weight gain over a 5-day period (i.e. days 7-12 of lactation) was used as an index of lactational performance in dams. Osmotic minipumps were used to infuse different doses of ovine (o) PRL into either the external jugular vein (JV) or the hepatic portal vein of the dams at a constant rate. The latter route of delivery would directly expose the liver to a higher concentration of PRL than would the former one. Twice daily sc injections of bromocriptine (1.5 mg/kg.injection) in corn oil into the dams completely suppressed litter weight gain. Infusion of oPRL into the JV at a dose of 2.0 mg/rat.day restored lactation to normal in the drug-treated mothers. Electrophoretic analysis indicated that about 95% of the oPRL remained in the intact monomeric form when incubated in the infusion solvent in the minipump at 37 C for 2 days, but by 4 and 6 days of incubation the amounts of that form decreased by about 25% and 50%, respectively. Measurement of serum oPRL levels by RIA showed that they were fairly constant, and after 5 days of infusion, the final concentration was directly related to the dose infused. Continuous infusion of oPRL into the JV was equally effective at restoring pup weight gain as was infusion into the hepatic portal vein over a wide range of doses. Hence, a physiological role of the liver in the maintenance of lactation by PRL is not supported by these experiments.     

Problems in the Diagnosis of Diverticulitis in the Young

Five cases of sigmoid diverticulitis in young patients are reported. The difficulty in obtaining preoperative diagnosis in these cases was due primarily to the fact that the diagnosis was not suspected because of their young age. Although diverticula were seen on barium enema in all cases, the "classical radiological pictures of diverticulitis" were not seen in three of the five cases, presumably because of a short duration of the illness. Diverticular disease of the colon in young patients appears to require more aggressive surgical approach in view of the fact that the disease is characterized by recurrent inflammations. These patients are presently followed up carefully with particular reference to recurrence of the disease in the rest of the bowel as they progress into "older age groups". There being no definite measures at present which are known to protect against the development of diverticulitis in the unaffected population, the question naturally arises, "will this group be even more susceptible?".