Human pituitary null cell adenomas and oncocytomas in vitro: effects of adenohypophysiotropic hormones and gonadal steroids on hormone secretion and tumor cell morphology.

Human pituitary null cell adenomas and oncocytomas are not associated with evidence of excess hormone secretion in vivo; their cellular derivation has not been clarified by morphologic investigation. In this study we examined 41 null cell adenomas and 58 oncocytomas in vitro to determine hormone release and its response to several adenohypophysiotropic hormones and gonadal steroids. In vitro, 96/99 tumors released LH, FSH, and/or alpha-subunit of glycoprotein hormones. TSH was released by 11 tumors. GH, PRL, and ACTH were found in small quantities in 11, 8, and 5 tumors, respectively. Only 3 tumors released no detectable hormones. Incubations with test substances were examined at 2- and 24-h periods for up to 72 h. All but 3 of 53 tumors showed marked and persistent increases in the release of LH, FSH, and/or alpha-subunit in response to GnRH in short and long duration experiments. Secretion of LH, FSH, or alpha-subunit was stimulated to more than 150% of control by TRH in 37/48 tumors, by CRH in 10/20, by GRH in 7/20. Estradiol, progesterone, and testosterone increased release of FSH, LH, and/or alpha-subunit in 23/32, 3/12, and 3/12 tumors, respectively, and reduced their release in 6/32, 5/12, and 7/12, respectively. In tumors which showed no response to gonadal steroids, GnRH in combination with estradiol, progesterone, or testosterone yielded the same result as GnRH alone; in tumors inhibited by gonadal steroids, GnRH in combination with one of those substances reduced the response to GnRH. No secretion of GH, PRL, ACTH, or TSH was detected after incubation with GRH, estradiol, CRH, or TRH except in the tumors which initially released GH, PRL, or TSH. Ultrastructural examination of cultured cells from 15 cases revealed morphologic alterations that correlated with changes in hormone release and could be quantified by morphometry. This study represents the largest analysis of hormone production and release in vitro and morphologic correlation of clinically nonfunctioning pituitary adenomas. The responsiveness of gonadotropin secretion by null cell adenomas and oncocytomas to GnRH and gonadal steroids resembles that of gonadotroph adenomas. However, the unexpected increases in gonadotropin release attributable to several other adenohypophysiotropic hormones and the release of multiple hormones suggests that null cell adenomas and oncocytomas may represent neoplasms derived from uncommitted or committed precursor cells that can undergo differentiation towards several cell lines.     

Membrane estrogen receptor-alpha interacts with metabotropic glutamate receptor type 1a to mobilize intracellular calcium in hypothalamic astrocytes

Estradiol, acting on a membrane-associated estrogen receptor-alpha (mERalpha), induces an increase in free cytoplasmic calcium concentration ([Ca(2+)](i)) needed for progesterone synthesis in hypothalamic astrocytes. To determine whether rapid estradiol signaling involves an interaction of mERalpha with metabotropic glutamate receptor type 1a (mGluR1a), changes in [Ca(2+)](i) were monitored with the calcium indicator, Fluo-4 AM, in primary cultures of female postpubertal hypothalamic astrocytes. 17beta-Estradiol over a range of 1 nm to 100 nm induced a maximal increase in [Ca(2+)](i) flux measured as a change in relative fluorescence [DeltaF Ca(2+) = 615 +/- 36 to 641 +/- 47 relative fluorescent units (RFU)], whereas 0.1 nm of estradiol stimulated a moderate [Ca(2+)](i) increase (275 +/- 16 RFU). The rapid estradiol-induced [Ca(2+)](i) flux was blocked with 1 microm of the estrogen receptor antagonist ICI 182,780 (635 +/- 24 vs. 102 +/- 11 RFU, P < 0.001) and 20 nmof the mGluR1a antagonist LY 367385 (617 +/- 35 vs. 133 +/- 20 RFU, P < 0.001). Whereas the mGluR1a receptor agonist (RS)-3,5-dihydroxyphenyl-glycine (50 microm) also stimulated a robust [Ca(2+)](i) flux (626 +/- 23 RFU), combined treatment of estradiol (1 nm) plus (RS)-3,5-dihydroxyphenyl-glycine (50 microm) augmented the [Ca(2+)](i) response (762 +/- 17 RFU) compared with either compound alone (P < 0.001). Coimmunoprecipitation demonstrated a direct physical interaction between mERalpha and mGluR1a in the plasma membrane of hypothalamic astrocytes. These results indicate that mERalpha acts through mGluR1a, and mGluR1a activation facilitates the estradiol response, suggesting that neural activity can modify estradiol-induced membrane signaling in astrocytes.     

Catechol O-methyltransferase val158-met genotype and individual variation in the brain response to amphetamine

Monamines subserve many critical roles in the brain, and monoaminergic drugs such as amphetamine have a long history in the treatment of neuropsychiatric disorders and also as a substance of abuse. The clinical effects of amphetamine are quite variable, from positive effects on mood and cognition in some individuals, to negative responses in others, perhaps related to individual variations in monaminergic function and monoamine system genes. We explored the effect of a functional polymorphism (val(158)-met) in the catechol O-methyltransferase gene, which has been shown to modulate prefrontal dopamine in animals and prefrontal cortical function in humans, on the modulatory actions of amphetamine on the prefrontal cortex. Amphetamine enhanced the efficiency of prefrontal cortex function assayed with functional MRI during a working memory task in subjects with the high enzyme activity val/val genotype, who presumably have relatively less prefrontal synaptic dopamine, at all levels of task difficulty. In contrast, in subjects with the low activity met/met genotype who tend to have superior baseline prefrontal function, the drug had no effect on cortical efficiency at low-to-moderate working memory load and caused deterioration at high working memory load. These data illustrate an application of functional neuroimaging in pharmacogenomics and extend basic evidence of an inverted-"U" functional-response curve to increasing dopamine signaling in the prefrontal cortex. Further, individuals with the met/met catechol O-methyltransferase genotype appear to be at increased risk for an adverse response to amphetamine.     

Change in Pulse Wave Velocity and Short‐Term Development of Cardiovascular Events in the Hemodialysis Population

The association between single measurements of carotid‐femoral pulse wave velocity (cfPWV) and cardiovascular (CV) events is driven by late events beyond 12 months of follow‐up. This prospective study compares single measurements of cfPWV vs the 2‐year delta cfPWV and the association with short‐term development of CV events in hemodialysis patients. cfPWV was performed at t=0 and t=1 two years later, and patients were followed‐up for development of CV events through 12 months (n=66). In Cox regression models adjusted for CV risk factors, history of CV events and delta cfPWV remained associated with the development of CV events (hazard ratio for prior CV events=8.9, P=.03; hazard ratio for delta cfPWV=1.14; P=.002). When delta cfPWV was substituted for single cfPWV measurement, none of the single measures were associated with new CV events. The change in cfPWV, but not single measurements of cfPWV, was associated with the development of CV events through 12 months.     

Urinary trypsinogen activation peptide (TAP) predicts severity in patients with acute pancreatitis

Summary Conclusions Urinary TAP obtained within the first 48 h of the onset of symptoms can distinguish patients with severe acute pancreatitis. Background Urinary trypsinogen activation peptide (TAP) has recently been described as an early marker of severity in acute pancreatitis. Methods In a multicenter study, urine samples were collected for TAP concentration at 6–12, 24, and 48 h after admission from 139 patients with acute pancreatitis (99 with mild disease, 40 with severe disease) and from 50 control patients. Severity of acute pancreatitis was defined by the presence of organ failure and/or pancreatic necrosis on dynamic contrast-enhanced computed tomography. Results Median urinary TAP in the 139 patients with acute pancreatitis compared to the 50 control patients was significantly higher at admission, 4.6 vs 0.8 ng/mL (p<0.001), and 6–12 h, 1.9 vs 0.55 ng/mL (p=0.04). Among patients who presented within 48h of the onset of symptoms, the median urinary TAP for severe pancreatitis (9 patients) compared to mild pancreatitis (40 patients) was significantly higher at admission, 29.6 vs. 3.6 ng/mL (p=0.001). Also, when obtained within 48h of the onset of symptoms, all patients with severe pancreatitis had an admission urinary TAP level>10 ng/mL. The sensitivity and specificity of an admission urinary TAP≥10 for severe pancreatitis was 100 and 85%, respectively. Given a cutoff of 10 ng/mL for an admission urinary TAP obtained within 48h of the onset of symptoms, the negative predictive value was 100% for mild pancreatitis.     

Preoperative insulin therapy as a marker for type 2 diabetes remission in obese patients after bariatric surgery

Background

Obesity not only increases the chances of developing diabetes—one of the top causes of death in the United States—but it also results in further medical complications.