Eliahu Golomb

Non-type I cystinuria caused by mutations in SLC7A9, encoding a subunit (b(o,+)AT) of rBAT

Cystinuria (MIM 220100) is a common recessive disorder of renal reabsorption of cystine and dibasic amino acids. Mutations in SLC3A1, encoding rBAT, cause cystinuria type I (ref. 1), but not other types of cystinuria (ref. 2). A gene whose mutation causes non-type I cystinuria has been mapped by linkage analysis to 19q12–13.1 (refs 3,4). We have identified a new transcript, encoding a protein (bo,+AT, for bo,+ amino acid transporter) belonging to a family of light subunits of amino acid transporters, expressed in kidney, liver, small intestine and placenta, and localized its gene (SLC7A9) to the non-type I cystinuria 19q locus. Co-transfection of bo,+AT and rBAT brings the latter to the plasma membrane, and results in the uptake of L-arginine in COS cells. We have found SLC7A9 mutations in Libyan-Jews, North American, Italian and Spanish non-type I cystinuria patients. The Libyan Jewish patients are homozygous for a founder missense mutation (V170M) that abolishes b o,+AT amino-acid uptake activity when co-transfected with rBAT in COS cells. We identified four missense mutations (G105R, A182T, G195R and G295R) and two frameshift (520insT and 596delTG) mutations in other patients. Our data establish that mutations in SLC7A9 cause non-type I cystinuria, and suggest that bo,+AT is the light subunit of rBAT.

Induction of Atypical Prostatic Hyperplasia in Rats by Sympathomimetic Stimulation

Prostatic innervation may participate in its homeostasis and growth. α‐Adrenergic inhibition alleviates clinical symptoms in benign prostatic hyperplasia. However, the prostatic effect of adrenergic agonists has not been investigated. This study deals with the prostatic effect of subchronic sympathomimetic stimulation.

Histologic atrial myolysis is associated with atrial fibrillation after cardiac operation

BACKGROUNDnPostoperative atrial fibrillation after cardiac operation is common. Despite the identification of risk factors associated with postoperative atrial fibrillation, the pathophysiologic mechanisms remain unclear. Myolysis has been recently described to be associated with maintenance of atrial fibrillation in experimental animals. In this study, we attempted to identify histopathologic changes in atria that might predict the development of postoperative atrial fibrillation, and specifically address its association with myolysis.nnnMETHODSnRight appendicular atrial tissue was sampled before and after cardiopulmonary bypass from 60 patients in sinus rhythm who underwent elective coronary artery bypass grafting.nnnRESULTSnFifteen patients (25%) developed postoperative atrial fibrillation. Histopathologic abnormalities were found in most patients (52 of 60). However, only myolysis and lipofuscin levels were found to be an independent histologic finding associated with the development of postoperative atrial fibrillation. Electron microscopy showed that myolytic vacuoles were not membrane bound, and were associated with lipofuscin deposits. Neither mitochondrial pathology nor apoptosis was detected in the atria before or after operation.nnnCONCLUSIONSnAbnormalities in biopsies before cardiopulmonary bypass can indicate the susceptibility to develop postoperative atrial fibrillation. This implies that the status of the atrium before cardiopulmonary bypass is a major determinant in the development of this common complication.

Dopamine increases glial cell line-derived neurotrophic factor in human fetal astrocytes

The use of fetal astrocytes for gene delivery into brains with neurodegenerative diseases has been suggested. Therefore, the effects of neurotransmitters in the brain on such cells are of interest. The presence of D1 (D1A) receptors and the effect of dopamine on a fetal human astrocyte cell line (SVG cells) in vitro were examined. SVG cells expressed D1 (D1A), but not D5 (D1B) receptors, as shown by RT‐PCR. Exposure to dopamine, apomorphine, and the specific D1 agonist, SKF‐38393, increased glial‐derived neurotrophic factor production of SVG cells, as well as intracellular free calcium. Exposure to the specific D1 antagonist, SCH 23390, blocked these effects. Thus, if implanted into a brain region rich in dopamine, or if transfected with the tyrosine hydroxylase gene, fetal astrocytes may serve as paracrine/autocrine cells capable of supplying critical growth factors to diseased brain tissue. GLIA 33:143–150, 2001.

Potential preoperative markers for the risk of developing atrial fibrillation after cardiac surgery.

Postoperative atrial arrhythmias after cardiac surgical procedures are common, with a reported overall incidence of approximately 50%. The pathophysiological mechanisms responsible for atrial fibrillation after a cardiac procedure remain unclear, although several clinical studies published during the past decade have identified certain preoperative risk factors associated with postoperative atrial fibrillation. In this study, we attempted to identify the histopathological changes in atrial cardiomyocytes that might predict the development of atrial fibrillation during the postoperative period. Atrial tissue from 60 patients was sampled before and after a cardiopulmonary bypass. Fifteen patients (25%) developed postoperative atrial fibrillation. The only clinical independent risk factor for the development of postoperative atrial fibrillation was chronic obstructive pulmonary disease (COPD) (P = .037). Histologically, there were 3 findings in the atrial myocardium that were more common in patients who developed postoperative atrial fibrillation: (1) vacuolation size (P = .017), (2) vacuolation frequency (P = .0136), and (3) lipofuscin content (P = .013). The identification of these histological markers for the development of postoperative atrial fibrillation may contribute not only to our understanding of the underlying pathophysiology that leads to postoperative atrial fibrillation but also to a method of preventing this troublesome complication of cardiac surgery.

Functional α3-glycine receptors in rat adrenal

Abstract The adrenal medulla contains high-affinity strychnine binding sites, presumed to be receptors for glycine. In this study, glycine injection (400 pmol) via a cannula attached to a microdialysis probe increased in vivo concentrations of catecholamines in the adrenal microdialysate in anesthetized rats. Strychnine perfusion (20 pmol/20 min) blocked these responses. To identify receptors potentially mediating this effect, we tested for RNA transcripts of the three known α subunits of strychnine binding site, using the reverse transcription-polymerase chain reaction. Only mRNA encoding the α 3 isoform was found in the rat adrenal. The findings suggest that in the rat adrenal, glycine stimulates catecholamine release by binding to strychnine binding sites and that those sites probably contain the α 3 isoform.

Effects of senescence and citral on neuronal vacuolar degeneration in rat pelvic ganglia.

A significant part of the morbidity in elderly men involves pelvic organs and their autonomic neural regulation. Environmental stimuli also impair the structure and function of pelvic organs. One of these factors is citral, a widely-used cosmetic fragrance constituent, which causes severe prostatic hyperplasia in rats. In this study, we assessed the effect of topical administration of citral (30 days) on the morphology of pelvic ganglia (PG) in young adult and old Wistar rats. Neuronal vacuolar degeneration with preserved nuclei of PG neurons was observed in untreated senescent, but not young rats. Citral significantly increased the rate of vacuolated neurons in old rats (from 3 to 14%), but only slightly in young ones (from 0 to 0.5-0.3%). Similar lesions were not found in inferior cervical or celiac ganglia, in either group. This shows that environmental stimuli enhance age-related processes of vacuolar neuronal degeneration in PG, and may contribute to the dysfunction of pelvic organs in the elderly.

Strychnine, Glycine, and Adrenomedullary Secretion

Publisher Summary Research suggests that strychnine and glycine interact with the agonist binding site of the nicotinic acetylcholine receptor (AChR) in chromaffin cells, thus exerting a pharmacological effect that may have a modulatory role on the AChR. The chromaffin cell has been extensively studied as a cholinergic neurosecretory system, and activation of the nicotinic receptor in these cells leads to the Ca 2+ dependent exocytotic release of catecholalmines, adenosine triphosphate (ATP), chromogranins, and enkephalins. These cells possess a high-affinity [ 3 H]strychnine binding site, and glycine can evoke catecholamine release from adrenomedullary tissue in vitro and in vivo , as demonstrated by the use of microdialysis techniques. The α 3 subunit of glycine receptors (but not the α 1 , or α 2 ) is expressed in rat adrenal and may mediate this effect. Strychnine inhibits the nicotinic stimulation of catecholamine release from cultured bovine adrenal chromaffin cells in a concentration-dependent (1–100 pM) manner. At 10 pM of nicotine, the IC 50 value for strychnine is approximately 30 pM. Strychnine also inhibits the nicotine-induced membrane depolarization and increase in intracellular Ca 2+ concentration. The inhibitory action of strychnine is reversible and is selective for nicotinic stimulation, with no effect observed on secretion elicited by a high external K + concentration, histamine, or angiotensin II.