Inhibitory effects of glucocorticoids on prolactin release induced by thyrotropin-releasing hormone in man

Glucocorticoid effect on thyrotropin-releasing hormone (TRH)-induced prolactin (PRL) release was studied in female patients with collagen or autoimmune diseases. Long-term, high dose glucocorticoid therapy tended to inhibit the response of plasma PRL to TRH. A negative correlation (r=-0.40) was found between the logarithm of total dose of glucocorticoids received and the magnitude of plasma PRL response to TRH (p less than .05).</p

Specificity of cultured anterior pituitary cells in detecting corticotropin releasing factor(s): the effect of biologically active peptides and neurotransmitter substances on ACTH release in pituitary cell cultures.

Biologically active peptides and neurotransmitter substances were added to anterior pituitary cell cultures to examine the presence of corticotropin releasing factor (CRF)-like activity. Hypothalamic extract (HE) induced significant dose-related increase of ACTH, and the lowest effective dose was 0.01 HE/ml. Other tested substances including luteinizing hormone-releasing hormone, thyrotropin releasing hormone, melanocyte stimulating hormone release inhibiting factor, somatostatin, substance P, neurotensin, beta-endorphin. leu-enkephalin, met-enkephalin, bradykinin, norepinephrine, dopamine, serotonin, acetylcholine, histamine, gamma-amino butyric acid or gamma-hydroxy butyric acid showed no CRF-like activity. Relatively high doses of lysine vasopressin, arginine vasopressin and angiotensin II increased the release of ACTH in pituitary cell cultures, but the maximal ACTH response was markedly less than with HE. These results indicate that cultured anterior pituitary cells are sensitive and fairly specific in detecting CRF(s) comparing with other detecting procedures.</p

A 14q+ chromosome in adult T-cell leukemia.

Chromosome studies were conducted on two patients with adult T-cell leukemia. In both patients, a marker chromosome 14q+ and a structural change involving chromosome 1 with trisomy of the q arm were found in peripheral blood leukocytes. The 14q+ marker chromosome had resulted from translocation from #5p in one patient and #5q in the other patient. The present and previous studies suggest that the donor chromosomes involved in the 14q+ translocation are variable. This indicates that the 14q+ marker chromosome rather than the donor chromosome is intimately related with adult T-cell leukemia.</p

A perifusion method for examining arginine vasopressin (AVP) release from hypothalamo-neurohypophyseal system.

A perifusion method has been developed using rat hypothalamo-neurohypophyseal system (HNS) or neural lobe to investigate the control mechanism of arginine vasopressin (AVP) release. A specific radioimmunoassay (RIA) for AVP was developed to measure AVP in perifusion medium employing anti-AVP serum which was obtained by immunizing rabbits. At a final dilution of 1/12,000, the antiserum showed less than 0.66 and 0.01% cross reactivity with lysine-vasopressin and oxytocin, respectively. But it did not cross reacted with other peptide hormones. The lowest detectable level of vasopressin was 0.5 pg/tube. The intra-assay coefficient of variation averaged 10.4%. The dilution curve of perifused medium was well paralled to the standard curve of AVP assay. AVP release from HNS or neural lobe gradually declined to the stable level in 90-120 min after the initiation of perifusion. Good repeatability of the AVP release from neural lobe was recognized by repeated stimulation with 10 min perifusion of 60 mM KCl at every 60 min. HNS released AVP in dose related manner to the osmotic challenge of sodium or glucose, and AVP release was stimulated from HNS by prostaglandin E2, but not by dopamine. These results show that the perifusion methods using AVP-RIA is a useful method to examine the AVP release from HNS or neural lobe.</p

A Case of Ectopic Renin-secreting Orbital Hemangiopericy-toma Associated with Juvenile Hypertension and Hypokalemia

An unusual case of orbital tumor with high renin content and severe hypertension is described. The patient was a 15-year-old girl with juvenile hypertension (200-140 mmHg) associated with right exophthalmos and hypokalemia. The patient showed extremely high levels of plasma renin activity and plasma aldosterone concentration. No difference was present in plasma renin activity from either side of the renal veins. Preoperatively, hypertension responded to treatment with spironolactone. The tumor could not be completely removed because of intracranial metastasis and infiltration, and the hyperreninemia and secondary hyperaldosteronism persisted. The renin content in the orbital tissue was 1,403-2,225 ng/angiotensin I generated/h/g wet weight of tissue. The postmortem histopathologic diagnosis was orbital hemangiopericytoma. This is the first case of extrarenal (ectopic) renin-secreting (or -producing) hemangiopericytoma of the orbital origin. Furthermore this case is worthy of note in the point of view of the presence of the extrarenal renin-angiotensin system, particularly in the brain.</p

Bartter's Syndrome — Case Report —

A 26-year-old female with Bartter's syndrome associated with Graves' disease is reported. This patient had a history of Graves' disease from the age of 22 and anti-thyroid drug (Methimazole) had been administered for 2 years. Thyroid function returned to normal but general fatigue and polyuria continued. Hypokalemia was diagnosed at 25 years of age and she was referred to our hospital for evaluation. Blood pressure was normal and laboratory data revealed normal thyroid function, hypokalemic alkalosis, high plasma renin activity and high plasma aldosterone concentration. She showed normal pressor sensitivity to norepinephrine infusion, grossly diminished pressor sensitivity to exogenous angiotensin II infusion compared with the normal. A renal biopsy specimen showed juxtaglomerular cell hyperplasia. Electron microscopy confirmed lacis cell (agranular cell) proliferation.</p

A different distribution of corticotropin releasing factor and arginine vasopressin contents in the hypothalamic nuclei after estrogen administration.

The distribution of corticotropin releasing factor (CRF) and arginine vasopressin (AVP) in hypothalamic nuclei were examined in control and estrogen-treated female rats. CRF activity was measured using monolayer cultured rat anterior pituitary cells and AVP by radioimmunoassay. Hypothalamic nuclei were punched out according to the method of Palkovits. The distribution of CRF activity in 5 different hypothalamic nuclei was similar to that of AVP in intact female rats. CRF activity in hypothalamic nuclei, pituitary ACTH content and plasma ACTH levels in estrogen-treated rats were not significantly different from those in control rats. However, significant elevation of AVP content was observed in the supraoptic and paraventricular nuclei of estrogen-treated rats. These results indicate that CRF and AVP are distributed in similar hypothalamic nuclei, but that they are not identical.</p

The effect of somatostatin analogue on glucose homeostasis in conscious dogs

Our aim was to clarify the effect of a somatostatin analogue (octreotide) on glucose flux in conscious dogs. We monitored the effects with catheters in the portal vein, hepatic vein and femoral artery and Doppler flow probes on the portal vein and hepatic artery before and after oral glucose administration. A significant increase of portal vein plasma flow after oral glucose was completely suppressed by both 4 and 1 &#956;g/kg octreotide. All doses of octreotide (4, 1 and 0.1 &#956;g/kg) suppressed the glucose-induced increment of arterial glucose by dose response. Only 4 &#956;g/kg of octreotide slightly but significantly suppressed hepatic glucose output. Marked suppression and delayed glucose absorption by the intestine was observed after 4 &#956;g/kg of octreotide. One and 0.1 &#956;g/kg octreotide also suppressed glucose absorption without delayed absorption. Total amounts of absorbed glucose during 3h after oral glucose were 24 ± 11% with 4 &#956;g/kg of octreotide, 37 ± 16% with 1 &#956;g/kg of octreotide, and 48 ± 8% with 0.1 &#956;g/ kg of octreotide, all of which were significantly less than that of the control (73 ± 8%). Using 4 &#956;g/kg of octreotide treatment, the liver took up only 5 ± 4% of the absorbed glucose, while the liver took up 35 ± 6% and 43 ± 9% of the absorbed glucose with 1 and 0.1 &#956;g/kg of octreotide. These latter values were similar to that of the control value of 34 ± 4%. In conclusion, we found that octreotide administered before oral glucose had a remarkable stabilizing effect on postprandial glycemic surges. Both the direct inhibitory effect of octreotide on portal vein plasma flow and impaired glucose absorption would contribute to this decreased postprandial hyperglycemia, while its suppressive effect on other hormones, such as insulin and glucagon, did not seem to influence the reduction of hyperglycemia.</p

Potent amyloidogenicity and pathogenicity of Aβ43.

The amyloid-β peptide Aβ42 is known to be a primary amyloidogenic and pathogenic agent in Alzheimer\u27s disease. However, the role of Aβ43, which is found just as frequently in the brains of affected individuals, remains unresolved. We generated knock-in mice containing a pathogenic presenilin-1 R278I mutation that causes overproduction of Aβ43. Homozygosity was embryonic lethal, indicating that the mutation involves a loss of function. Crossing amyloid precursor protein transgenic mice with heterozygous mutant mice resulted in elevated Aβ43, impairment of short-term memory and acceleration of amyloid-β pathology, which accompanied pronounced accumulation of Aβ43 in plaque cores similar in biochemical composition to those observed in the brains of affected individuals. Consistently, Aβ43 showed a higher propensity to aggregate and was more neurotoxic than Aβ42. Other pathogenic presenilin mutations also caused overproduction of Aβ43 in a manner correlating with Aβ42 and with the age of disease onset. These findings indicate that Aβ43, an overlooked species, is potently amyloidogenic, neurotoxic and abundant in vivo