Metabolism of amino- and carboxyl-sequence immunoreactive parathyroid hormone in the bovine: evidence for peripheral cleavage of hormone.

Radioimmunoassays that detect specifically peptide sequences within either the biologically active amino region (N-assay) or inactive carboxyl region (C-assay) of parathyroid hormone (PTH) were used to evaluate the metabolism of PTH during and after infusion and injection of homogeneous (containing less than 0.1% hormonal fragments) intact bovine PTH (bPTH) into calves. During continuous infusions of hormone, when constant blood levels of immunoreactive PTH were reached, a dissociation between the concentrations of amino versus carboxyl immunoreactivity was observed; concentrations of hormone measured by the C-assay rose to a level of approximately three times higher than that measured by the N-assay. Analysis by gel filtration of immunoreactive PTH in plasma samples from calves after injection of hormone showed the rapid disappearance of intact hormone (N- and C-assays) and the appearance of a large fragment detected by the C-assay but not by the N-assay. The hormonal fragment lacked antigenic determinants within the amino peptide sequence required for biologic activity. No additional fragments of PTH were detected by gel filtration using the N- and C-assays. No detectable conversion of intact PTH to hormonal fragments occurred during incubation in vitro in bovine serum. The results are consistent with the concept that PTH is metabolized after entry into the circulation at peripheral sites located outside the vascular space, resulting in the rapid disappearance from blood of intact hormone and the appearance of a biologically inactive hormonal fragment(s). These studies done in calves agree with earlier studies done in dogs and man and point to the existence in mammals of common pathways for the peripheral metabolism of PTH.     

Managing common endocrine disorders amid COVID-19 pandemic

Background and aimsThe novel coronavirus disease (COVID-19) pandemic and the resulting nationwide lockdowns have posed a major challenge to the management of pre-existing and newly diagnosed endocrine disorders. Herein, we have summarized the management approaches of common endocrine disorders amid the ongoing pandemic.MethodsWe have performed an extensive literature search for articles in PubMed, EMBASE and Google Scholar databases till 25 May 2020, with the following keywords: “COVID-19”, “diabetes mellitus”, “thyroid disorders”, “primary adrenal insufficiency”, “Cushing’s syndrome”, “pituitary tumors”, “vitamin D″", “osteoporosis”, “primary hyperparathyroidism”, “hypoparathyroidism”, “management”, “treatment” and “guidelines” with interposition of the Boolean operator “AND”.ResultsWe have summarized the most feasible strategies for the management of diabetes mellitus, thyroid disorders, primary adrenal insufficiency (including congenital adrenal hyperplasia), Cushing’s syndrome, pituitary tumors, osteoporosis, primary hyperparathyroidism and hypoparathyroidism amid the constraints laid down by the raging pandemic. In general, medical management should be encouraged and surgical interventions should be deferred whenever possible. Ongoing medications should be continued. Sick-day rules should be sincerely adhered to. Regular contact with physicians can be maintained through teleconsultations and virtual clinics.ConclusionsConsidering the burden of endocrine disorders in the general population, their management needs to be prioritized amid the ongoing COVID-19 pandemic.     

Thyroid function in patients undergoing maintenance hemodialysis: unexplained low serum thyroxine concentration.

Thyroid function was studied in 55 patients undergoing maintenance hemodialysis who were all judged to be clinically euthyroid. The dialysis patients, in comparison to normal control subjects, had significantly lower mean values for serum T4 (4.0 +/- 1.4 [SD] microgram/dl versus 7.9 +/- 1.5 microgram/dl, p less than 0.001), T3 (118 +/- 31 ng/dl versus 147 +/- 28 ng/dl, p less than 0.001), free T4 measured by equilibrium dialysis (1.22 +/- 0.38 ng/dl versus 2.15 +/- 0.67 ng/dl, p less than 0.001), free T3, free T4 index, and free T3 index. Serum TBG, measured by radioimmunoassay, was similar to that of the controls and serum TSH, 2.2 +/- 1.3 micromicron/ml, was also similar to that of control values, 2.0 +/- 1.1 micromicron/ml. The serum PBI did not change during the dialysis procedure, but serum inorganic iodine fell slightly from 2.1 +/- 1.1 microgram/dl before dialysis to 1.2 +/- 0.6 microgram/dl after dialysis (p less than 0.05). The marked reduction in serum total T4 and free T4 concentrations and the moderate reduction in serum total T3 and free T3 levels in apparently euthyroid patients undergoing hemodialysis has not been explained. The normal serum TSH levels in the face of these low concentrations of thyroid hormone suggests an abnormality in the control of TSH secretion in these patients.     

直肠癌内分泌样癌细胞分化与P^53蛋白表达关系的研究

目的：研究直肠癌内分泌样癌细胞分化与Ｐ＾５３蛋白表达的关系及意义。方法：采用免疫组织化学ＡＢＣ法检测４４例福尔马林固定、石蜡包埋的直肠癌手术切除及活检组织中的嗜铬蛋白Ａ（ＣＧＡ）及Ｐ＾５３蛋白的表达。结果：Ｐ＾５３、ＣＧＡ阳性表达率分别为６８．２％和３８．６％：ＣＧＡ阳性及阴性直肠癌Ｐ＾５３表达率分别为８８．２％和５５．６％，两者比较Ｐ〈０．０２５Ｘ＾２检测；Ｐ＾５３ＣＧＡ在分化差的直肠癌中的表达     

低频小探头超声内镜对胰腺内分泌肿瘤术前定位诊断的价值

目的 评价低频小探头超声内镜检查(LFMPS)在胰腺内分泌肿瘤术前定位诊断中的临床价值。方法 2000年6月至2002年6月期间21例临床拟诊为胰腺内分泌肿瘤的患者术前行腹部 B超、螺旋 CT、磁共振(MRI)及 LFMPS探查(Fujinon 7.5 MHz低频小探头超声及超声系统),检查结果与外科术中定位和病理结果对照,评估LFMPS对胰腺内分泌肿瘤的术前定位诊断价值。结果21例患者中17例经外科手术及术后病理证实为内分泌肿瘤,4例未手术。其中胰岛素瘤16例(头部9例、体部 3例、尾部4例),胰腺外血管活性肠肽瘤1例,检出病灶的平均直径 2.02 cm。LFMPS确诊14例(82.4％),B超确诊9例(52.9％),螺旋CT确诊15例(88.2％),MRI确诊12例(70.6％),其中LFMPS对位于胰腺头、体部肿瘤以及直径<1cm病灶的确诊率优于其他常规影像方法。结论LFMPS对胰腺内分泌肿瘤的术前定位诊断准确率较高,且与肿瘤的位置与大小有关。     

Leptin inhibition of insulin secretion from isolated human islets

Leptin is a hormone produced and secreted from the adipose tissue. Its physiological actions include the regulation of satiety, food intake and energy balance. The production of leptin is increased by high insulin levels. Here, we demonstrate that leptin acts as an inhibitor of glucose-induced (20 mM) insulin secretion from isolated human islets. No effect was observed in the presence of lower glucose levels (2.8 and 10 mM glucose). The pancreatic β-cell might represent a target of a direct physiological action of leptin. We suggest the presence of an “adipo-insular axis” in which leptin mediates negative feedback from the adipose tissue to the endocrine pancreas. Received: 21 July 1997 / Accepted in revised form: 1 October 1997     

Effects of the disaccharidase inhibitor acarbose on meal and intravenous glucose tolerance in normal man

To determine whether the effects of the disaccharidase inhibitor Acarbose on glucose tolerance could be solely explained via an action on intestinal nutrient absorption, the effects of this agent and placebo (100 mg p.o.) on intravenous and postprandial glucose tolerance were compared in six normal subjects. Acarbose significantly diminished plasma glucose, insulin, and gastrointestinal inhibitory polypeptide responses following meal ingestion without affecting plasma glucagon and pancreatic polypeptide responses, but had no effect on plasma glucose and insulin responses following intravenous injection of glucose. These results suggest that the acute effects of Acarbose on glucose tolerance can be explained on the basis of its ability to alter intestinal nutrient absorption.     

Mood and metabolic consequences of sleep deprivation as a potential endophenotype’ in bipolar disorder

It has been commonly recognized that circadian rhythm and sleep/wake cycle are causally involved in bipolar disorder. There has been a paucity of systematic research considering the relations between sleep and mood states in bipolar disorder. The current study examines the possible influences of sleep deprivation on mood states and endocrine functions among first-degree relatives of patients with bipolar disorder and healthy controls. Blood samples were taken at two time points in the consecutive mornings at predeprivation and postdeprivation periods. Participants simultaneously completed the Profiles of Mood States at two time points after giving blood samples. Plasma T3 and TSH levels increased after total sleep deprivation in both groups. Sleep deprivation induced TSH levels were reversely associated with depression–dejection among healthy controls. A paradoxical effect was detected for only the first-degree relatives of the patients that changes in plasma cortisol levels negatively linked to depression–dejection and anger–hostility scores after total sleep deprivation. Plasma DHEA levels became correlated with vigor-activity scores after sleep deprivation among first-degree relatives of bipolar patients. On the contrary, significant associations of depression–dejection, anger–hostility, and confusion–bewilderment with the baseline plasma DHEA levels became statistically trivial in the postdeprivation period. Findings suggested that first-degree relatives of patients with bipolar disorder had completely distinct characteristics with respect to sleep deprivation induced responses in terms of associations between endocrine functions and mood states as compared to individuals whose relatives had no psychiatric problems. Considering the relationships between endocrine functions and mood states among relatives of the patients, it appears like sleep deprivation changes the receptor sensitivity which probably plays a pivotal role on mood outcomes among the first-degree relatives of patients with bipolar disorder.