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Biomedical subjects

L Goldstein

Publications and source records attributed to L Goldstein.

341 records · Page 19Linked to original sources
PubMedDate not supplied

Protection by nicotine from behavioral disruption caused by reticular formation stimulation in the rat.

Male Sprague-Dawley rats prepared with chronic electrodes in the mesencephalic reticular formation were trained to perform on a visual attention task. Short trains of electric current delivered to the reticular formation effectively blocked performance in a reversible and reproducible fashion. Subcutaneous administration of 100 mug/kg nicotine (as the base) served to attenuate the behavioral disruption caused by reticular stimulation. The suggestion that it is a nicotine-induced limbic system activation which antagonizes the behavioral disruption caused by electrically-induced reticular over-activation, is discussed.

Animals↗
PubMedDate not supplied

Age-dependent spontaneous EEG bursts in rats: effects of brain phosphatidylserine.

During aging, male Sprague-Dawley rats display increasing frequency of bursts of seizure-like EEG patterns. They also have a decreased retention of passive avoidance response and a loss of spontaneous alternation in a Y maze. A study was made on the effects of chronic administration of phosphatidylserine in aged rats. It was found that BC-PS reduced by 65% the number of seizures, and by 70% their duration. It also facilitated retention of passive avoidance and of spontaneous alteration behavior. These results suggest that phosphatidylserine can affect electrophysiological and behavioral parameters in aged rats probably by counteracting age-related biochemical changes.

Aging↗
PubMedDate not supplied

Psychophysiologic correlates of nocturnal penile tumescence in normal males.

Despite increasing clinical reliance on nocturnal penile tumescence (NPT) testing for the differential diagnosis of male impotence, little is known at present about the relationship between NPT and other aspects of sleep and waking psychophysiology. This study investigated patterns of NPT, sleep, and EEG hemispheric asymmetry in 20 male subjects, using standard polysomnographic laboratory procedures for the assessment of sleep and NPT, and a method of EEG amplitude integration developed by Goldstein. Additionally, the effects of daytime sexual activity and mood state on the duration and amplitude of NPT were studied. Overall, the results of this study confirmed the well-documented relationship between NPT and stage REM, as well as demonstrating a strong association between NPT phase and nondominant hemisphere activation. Furthermore, this association appeared to strengthen over the course of the night. Hemispheric asymmetry and stage REM were also closely linked throughout. On the other hand, no significant correlations were found between daytime sexual activity or mood state and NPT. It is suggested that concurrent assessment of hemispheric asymmetry may strengthen the diagnostic power of NPT testing in impotence cases involving central organic etiology.

Adult↗
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Cell membrane surface expression and tyrosine kinase regulate the osmolyte channel (skAE1) in skate erythrocytes.

A regulatory volume decrease response occurs when skate (Raja erinacea) erythrocytes are exposed to hyposmotic medium; they swell and then reduce their volume by releasing organic osmolytes (primarily taurine) and associated water. The response involves the red blood cell anion-exchanger skate anion-exchanger 1 (skAE1), which has been previously shown to be affected by tyrosine phosphorylation, to form tetramers and to change binding affinities to the cytoskeletal proteins, ankyrin and band 4.1. Our recent studies are focused on determining the sequence and mechanism of these events to better understand the activation of skAE1 upon hyposmotic stimulation. Under isosmotic conditions a large portion of skAE1 is found not only on the plasma membranes but also associated intracellularly in detergent-resistant membranes or lipid rafts. We hypothesize that an important step in the hyposmotic-induced increase in taurine transport involves the movement of skAE1 from an intracellular association with lipid rafts into the cell membrane. Inhibition of tyrosine phosphorylation of skAE1 with piceatannol reduces the hyposmotic-induced increase in taurine transport and also inhibits both the decreased binding of skAE1 to band 4.1 and the increased affinity to ankyrin. However, the phosphorylation inhibitor does not block the movement of the transporter into the plasma membrane or the formation of tetramers. This suggests that tyrosine phosphorylation is important in the hyposmotic-induced taurine transport but other steps that do not require phosphorylation play an important role.

Animals↗
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alpha-Ketoglutarate regulation of glutamine transport and deamidation in renal mitochondria.

alpha-Ketoglutarate (KG) is a potent inhibitor of renal mitochondrial glutamine transport and deamidation at physiological concentrations. The concentration-inhibition relationship observed between KG and mitochondrial glutamine transport and deamidation indicates that changes in renal KG concentration occurring during alterations in acid-base balance would have significant effects on mitochondrial ammonia production in vivo. A rapid-mixing, rapid-filtration method was developed to measure the effects of KG on initial rates of mitochondrial glutamine transport. Transport was linear for only a few seconds and approached steady-state conditions by 30 seconds. KG (0.3 mM) raised the glutamine transport Km approximately two-fold. We propose that KG may play a major regulatory role in the early adaptation of renal ammonia production to acidosis.

Acid-Base Equilibrium↗
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Amino acids and cell regulation.

Free amino play an important role in regulating cell volume in fishes. Four tissues/cells (skeletal muscle, RBC, brain, and myocardium) of the little skate, Raja erinacea, were selected for detailed study because of their special importance or unique advantage as experimental models. Three particular amino acids, beta-alanine, taurine, and sarcosine play a predominant role in all four tissues. As in higher vertebrates, amino acid uptake in skate brain, heart, and RBC is mediated via a Na+-dependent process. Amino acids leave the skate brain rapidly in response to a sudden decrease in plasma osmolality and/or to a simultaneous drop in extracellular Na+ concentration. However, although amino acids are important for volume regulation in normal brain cells, they do not appear to be likely candidates for the unidentified "idiogenic" osmolytes in mammalian brain cells. The high concentration of taurine in skate myocardium is of special interest because of the special role of this amino acid in myocardial contractility. Thus, unlike beta-alanine and sarcosine, taurine may play a dual role in regulating both cell volume and contractility of myocardial cells. The isolated skate atrium is well suited for in vitro studies of these two processes.

Amino Acids↗
PubMedDate not supplied

Keratomycosis in a Percheron cross horse caused by Cladorrhinum bulbillosum.

This report describes an infection of a horse's cornea caused by Cladorrhinum bulbillosum. Minor surgery and treatment with antibiotics successfully resolved the infection. The only previous reported case involving this fungus was an Argentinian boy who was infected while working with horses.

Animals↗