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L Goldstein

Publications and source records attributed to L Goldstein.

At least 55 records · Page 3Linked to original sources
PubMed1998

Hypotonic-stimulated taurine efflux in skate erythrocytes: regulation by tyrosine phosphatase activity.

Treatment of skate erythrocytes with FCCP, dinitrophenol, or sodium azide lowers ATP levels and inhibits Na+-independent taurine uptake after hypotonic volume expansion. Inside-out vesicles isolated from hypotonic volume-expanded cells demonstrate greater Na+-independent taurine uptake, and pretreatment of cells with FCCP abolishes this stimulation. Addition of ATP to the vesicles does not restore stimulated taurine uptake, suggesting that ATP does not act as a ligand modulator on the transporter. Therefore the role of protein phosphorylation was investigated. Because known protein kinase inhibitors have previously been found to have little effect on taurine fluxes in skate erythrocytes, we focused on the effects of protein phosphatase inhibition. When volume-expanded cells were returned to isotonic medium, taurine flux returned to basal values more slowly after treatment with the tyrosine phosphatase inhibitor pervanadate, suggesting that dephosphorylation may regulate inactivation. A similar effect of phosphatase inhibitors was observed in the inside-out vesicles from volume-expanded cells: the reversal of stimulated taurine uptake takes place more slowly in vesicles prepared from cells that had been incubated with pervanadate. Band 3, a major protein involved in the taurine transport pathway, shows increased tyrosine phosphorylation after hypotonic volume expansion. Pervanadate treatment of the cells potentiates and prolongs the increased phosphorylation. Therefore tyrosine phosphorylation of band 3 may play an important role in the activation of taurine fluxes after volume expansion.

Adenosine Triphosphate↗
PubMed1998

Reliability and validity of the SA-45: further evidence from a primary care setting.

A project designed to demonstrate the benefits of integrating behavioral healthcare services in primary medical care settings provided an opportunity to further investigate the psychometric properties of the SA-45 using data from a sample of 126 adults seeking medical services in a family practice setting. Specifically, the appropriateness of the SA-45 s adult nonpatient norms, as well as cross-validation of its test-retest reliability and construct validity, was investigated from the first set of data gathered for this project. The results suggested that use of the SA-45 nonpatient norms with primary care populations is appropriate. Three-month test-retest correlations between Depression scale scores and SA-45 and SA-24-predicted GSI scores were found to be moderate but highly significant. In addition, correlations among the SA-45 scales and indices and their correlations with the SF-12 Mental and Physical Component Summary scales added further support for the psychometric integrity of the SA-45. Finally, only partial indirect support was obtained for the SA-45 s ability to accurately classify patients as requiring further evaluation for behavioral health problems. Limitations of the study are discussed and suggestions for future research are presented.

Adolescent↗
PubMed1997

Volume-activated osmolyte channel in skate erythrocytes: inhibition by pyridoxal derivatives.

Volume expansion of erythrocytes of little skate, Raja erinacea, triggers the opening of an osmolyte channel. We review this transport mechanism and further investigate the channel's physicochemical nature by probing the channel with a series of pyridoxine derivatives in skate RBC as well as in epithelial cells: MDCK and C6 glioma cells and in skate hepatocytes. The identity of the transport mechanism (band 3 vs. an anion channel) which mediates the swelling-activated efflux of osmolytes in fish RBC is controversial. Therefore, we compared taurine and Cl- effluxes in similar conditions. We found that there is significant Cl- loss from volume-expanded skate RBC. However, there was no effect of either hypotonicity or a number of taurine transport inhibitors on this loss. Utilizing changes in intracellular pH as a means of indirectly measuring H+/Cl- cotransport, we found that a rise in cell pH accompanied the loss of Cl-. This suggests that Cl- efflux could occur via a H+/Cl- cotransporter. To probe and compare the osmolyte channel (taurine efflux) of the skate RBC and three other cell types we used a family of pyridoxine inhibitors. The inhibitory patterns for the skate erythrocytes and hepatocytes differed from those for MDCK and C6 glioma cells and the two former cell types differed from each other. Therefore, the results show that the osmolyte channel in the skate differs from that in other epithelial cells with regard to pyridoxine derivative binding properties.

Animals↗
PubMed1997

Hypotonic stress induces translocation of the osmolyte channel protein pICln in embryonic skate (Raja eglanteria) heart.

Volume expansion of cardiac cells from a wide variety of species stimulates the efflux of the beta-amino acid taurine through an osmolyte channel. Previous studies have suggested that the osmolyte channel in epithelial cells is a swelling-activated anion channel (pICln). In skate heart, a 37-kDa protein is present which is recognized by a specific antibody to a protein characterized in MDCK cells as pICln. This protein is present predominantly in the cytosol (only 10% in the membrane fraction) of heart incubated under isotonic conditions. After transfer to hypotonic medium (one-half osmolarity), the distribution of this protein is markedly altered and significant amounts of the protein are found in the membrane fraction. After hypotonic exposure, the amount of the protein in the membrane fraction rises to 38 +/- 11% (range 18-53, n = 3). The translocation to the membrane fraction suggests that this protein may play a role in the taurine efflux in this tissue stimulated by hypotonic stress.

Animals↗
PubMed1997

Coccidioidomycosis in liver transplant patients.

Eight (0.59%) of 1,347 patients who underwent liver transplantation at the UCLA Medical Center (Los Angeles) developed coccidioidomycosis. Whereas only one case occurred during the first 8 years and 10 months of the UCLA Liver Transplant Program (February 1984 to December 1992), seven cases occurred within the following 23-month period (December 1992 to November 1994). The median time of onset for infection after transplantation was 8 weeks (range, 4-312 weeks). Clinical presentations of patients with coccidioidomycosis included pneumonia (six cases), pneumonia with meningitis (one case), hepatitis (one case), and monoarticular arthritis (one case). Despite therapy with amphotericin B alone (six cases) or amphotericin B plus fluconazole (two cases), infection was fatal in four of eight cases. As of this writing, the four surviving patients are receiving chronic maintenance therapy with either fluconazole (three patients) or itraconazole (one patient). These experiences show that coccidioidomycosis can be a serious and frequently fatal infection after liver transplantation and that the incidence of this disease appears to be increasing.

Adult↗
PubMed1996

High affinity binding of ankyrin induced by volume expansion in skate erythrocytes.

Volume expansion of little skate (Raja erinacea) erythrocytes increases the affinity of ankyrin binding without altering in the number of binding sites. Potassium iodide-stripped inside-out vesicles (KI-IOV) were used to assess ankyrin binding under volume-expanded conditions. Under isoosmotic conditions, ankyrin binds nearly exclusively to a single class of sites (Bmax, 52 +/- 12 microg/mg; Kd, 150 +/- 28 nM). KI-IOV from volume-expanded cells (either with one-half osmolarity medium or with inclusion of the permeant solute ethylene glycol) demonstrate two ankyrin-binding populations. A high affinity population occurs transiently under volume-expanded conditions. This population has a Bmax of 18 +/- 7 microg/mg and a Kd of 25 +/- 9 nM. Total binding of high and low affinity sites is 57 +/- 17 microg/mg. This change in ankyrin affinity is reversible on volume regulatory decrease. A major target protein in the KI-IOV was identified as the skate homolog of the mammalian red cell anion exchanger band 3. Inclusion of the purified cytoplasmic domain of band 3 competes away more than 80% of the ankyrin binding. To determine whether increased ankyrin affinity is due to band 3 tetramer formation that occurs in volume expansion, cells were treated with pyridoxal 5-phosphate or 4,4'-dinitrostilbene-2,2'-disulfonic acid, two agents that increase tetramer formation under isoosmotic conditions. Both treatments altered the binding affinity with a shift toward higher affinity binding without significant alteration in the number of binding sites.

Animals↗
PubMed1996

Erythropoietin stimulates tyrosine phosphorylation and taurine transport in skate erythrocytes.

Taurine, a beta amino acid, is a primary osmolyte in nucleated skate erythrocytes and is involved in the regulation of cell volume. Growth factors may be involved in the regulation of cell volume which occurs during cell division. Erythropoietin (EPO) is the primary growth factor controlling erythropoiesis. To investigate its mechanism of action, we used nucleated skate erythrocytes. EPO stimulates Na(+)-independent uptake of taurine in a concentration-dependent manner. The uptake was inhibited by the tyrosine kinase inhibitor genistein. Concomitantly, EPO stimulates tyrosine phosphorylation of a number of proteins, particularly ones of molecular masses 145, 120, 100, 80, 65, and 35 kDa. Using specific antibodies, the 145 kDa protein is identified as phospholipase C gamma-1 (PLC gamma-1) and the 100 kDa protein as the skate homolog of the anion exchanger band 3. Since PLC gamma-1 is activated, turnover of membrane lipids was determined. EPO increased 1,2-diacylglycerol formation from phosphatidylinositols (phosphatidylinositol-4-monophosphate and 4,5-biphosphate) during an early phase and later preferentially from phosphatidylcholine. The early hydrolysis of phosphoinositides was confirmed measuring generation of inositol-1,4,5-trisphosphate, demonstrating an activation of PLC gamma-1 activity. To determine if phospholipase D (PLD) stimulation also occurred, ethanol was included in the reactions. Phosphatidylethanol, synthesized by PLD-mediated transphosphatidylation, appeared at times longer than 5 min, suggesting delayed activation of PLD. These results demonstrate that EPO, via simulation of tyrosine phosphorylation, stimulates taurine transport in skate erythrocytes.

Animals↗
PubMed1996

Organic osmolyte channels: transport characteristics and regulation.

Erythrocytes of the skate (Raja erinacea) exposed to hypotonic stress swell and then undergo a volume regulatory decrease by releasing taurine and other osmolytes. Previous studies showed that taurine release occurs via a volume-activated, Na(+)-independent, bi-directional transporter that has the properties of a size-limited channel. We now report on the transport characteristics of this channel and its regulation. Kinetic, competition and inhibitor studies indicate that polyols (myo-inositol) and trimethylamines (betaine) are transported by the same channel as taurine. Although the identity of the channel is still unknown a variety of evidence suggests that band 3 is involved in either channel formation or regulation. Hypotonicity causes phosphorylation and structural changes in band 3. Under isotonic conditions band 3 is predominantly in the dimeric form. Hypotonicity causes a shift to tetrameric band 3. We hypothesize that the band 3 tetramer either forms or regulates an osmolyte channel. The finding that expression of band 3 protein increases osmolyte channel activity in Xenopus oocytes supports this hypothesis.

Animals↗
PubMed1996

"Gamekeeper's thumb" variant, complicated by reflex sympathetic dystropy.

A case of gamekeeper's thumb resulting from a motor vehicle accident is presented. This injury was complicated by the onset of reflex sympathetic dystrophy. An overview of the presentation and management of these disorders, which may result in severe disability without prompt recognition and therapy, is submitted for discussion.

Adult↗
PubMed1996

Reproducibility of MEG auditory evoked field source localizations in normal human subjects using a seven-channel gradiometer.

Magnetoencephalographic (MEG) auditory evoked fields (EF) were recorded from 12 normal adult subjects over both hemispheres on two separate occasions at least one week apart using a seven-channel second-order gradiometer. Stimuli were computer-generated at 25-msec duration, 1 kHz tone pips. Responses to 100 stimuli were averaged, and source estimates with confidence intervals were computed, for the 100-msec latency auditory EF component, termed M100. Root-mean-squared (rms) differences in x, y, and z locations were approximately 0.7 cm on the two occasions; strength and orientation differences were 18 nA-m and 11 degrees, respectively. This spatial accuracy using a seven-channel instrument, compares favorably with other currently available technologies for localization of brain function.

Adult↗
PubMed1996

Chloride and taurine effluxes occur by different pathways in skate erythrocytes.

The aim of this study was to determine whether volume-activated taurine and Cl- effluxes occur via the same system in skate (Raja erinacea) red blood cells (RBC). The effluxes were measured in isotonic and hypotonic elasmobranch Ringer solutions, in which NaCl was replaced by mannitol and the remaining exchangeable anions with gluconate. Methazolamide (0.1 mM) was added to minimize HCO3- formation. RBC Cl- content fell approximately 50%/h in both isotonic and hypotonic media, with no detectable K- loss in either medium. The observed Cl- loss was accompanied by an increase in pH. Both the Cl- loss and pH rise were inhibited by 4,4'- diisothiocyanostilbene-2,2'-disulfonic acid (0.1 mM), suggesting that Cl- efflux was due to H(+)-Cl- cotransport. 36Cl- effluxes in isotonic and hypotonic media were (means +/- SE, n = 11) 2.8 +/- 0.6 and 3.5 +/- 0.9 mumol.g dry wt RBC-1.min-1, respectively, whereas [3H]taurine effluxes in the same media were 0.045 +/- 0.02 and 2.1 +/- 0.05 mumol.g dry wt RBC-1.min-1, respectively (n = 6). These results indicate that taurine and Cl- effluxes occur via different pathways in skate RBC. In addition, the swelling-activated Cl- channel reported in epithelial cells does not appear to be present in skate RBC. This conclusion was confirmed by Western blots with an antibody to swelling-activated Cl- channels. Taurine and Cl- fluxes are apparently under different pathway influences in these RBC: taurine diffuses via a channel, whereas Cl- is transported by cotransporters.

Animals↗
PubMed1996

Band 3 in cell volume regulation in fish erythrocytes.

Erythrocytes of the skate (Raja erinacea) demonstrate a regulatory volume decrease response when exposed to hypotonic stress by releasing taurine and other organic osmolytes. We review the transport characteristics, physical changes and signaling pathways of a volume-activated osmolyte channel associated with band 3 in skate red blood cells that can be distinguished from anion channels and is separate from the anion exchanger function of band 3.

Animals↗