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P E Golstein

Publications and source records attributed to P E Golstein.

11 recordsLinked to original sources
PubMed2004

Hypotonic cell swelling stimulates permeability to cAMP in a rat colonic cell line.

This study characterized the membrane permeability to cAMP in a cell line derived from the rat colon (CC531(mdr+)) by comparison of fluxes of 3H-cAMP, 3H-8-bromo-cAMP, 3H-taurine, 3H-adenosine and 3H-5'AMP under various experimental conditions including cell membrane depolarization and hypotonic cell swelling. Cell volume was modified by changing the osmolality and composition of the extracellular medium. Incubation in iso- and hypotonic KCl media induced graded increases in cell volume and stable activation of volume-sensitive channels that was reflected in an increased efflux of 3H-taurine. Incubation in hypotonic KCl solution also enhanced the efflux of 3H-8-Br-cAMP (a non-hydrolysable analogue of cAMP). Both the efflux of 3H-taurine and of 3H-8-Br-cAMP were inhibited by 5-nitro-2-(3-phenylpropylamino)benzoate (NPPB, 100 microM) suggesting the involvement of volume-sensitive anion channels. To gain further insight into the route mediating cAMP permeability, the uptakes of 3H-cAMP, 3H-8-Br-cAMP and 3H-taurine were determined over short (5-min) periods. Uptakes of these substrates demonstrated close similarities: comparable increases were observed that correlated with the increases in cell volume in iso- and hypoosmotic KCl media; they were inhibited strongly by NPPB (100 microM) and metabolic inhibitors (deoxyglucose, 20 mM together with the mitochondrial uncoupler carbonylcyanide p-(trifluoromethoxy)phenylhydrazone, FCCP, 10 microM) while barely reduced by dipyridamole (100 microM) and they were not affected by adenosine (1 mM). In contrast, the uptakes of 3H-adenosine and 3H-5'AMP had strikingly different properties; they were insensitive to cell swelling; barely inhibited by NPPB (100 microM) and metabolic inhibitors (deoxyglucose and FCCP) while strongly reduced by dipyridamole (100 micro M). Unlike the uptakes of 3H-cAMP, 3H-8-Br-cAMP and 3H-taurine, the uptakes of 3H-adenosine and 3H-5'AMP were reduced in Na(+)-free media, suggesting the presence in this cell line of two different adenosine carriers, one sodium-dependent and one sodium-independent. Taken together the present data show that in this rat colonic cell line, cAMP permeability is increased by cell swelling in hypotonic KCl medium and inhibited by NPPB and metabolic inhibitors. The similarity of these characteristics to those of taurine permeability suggests the involvement of a volume-sensitive anion pathway.

Animals↗
PubMed2004

Reversible myopathy during successful treatment with pegylated interferon and ribavirin for acute hepatitis C.

There is no standard approved treatment for acute hepatitis C and the combination of pegylated interferon-alpha and ribavirin, currently recognized as the standard of care for chronic hepatitis C, has not been evaluated for acute hepatitis C. Adverse events induced by interferon therapy are numerous but myopathy is rare and has not been described with the use of pegylated interferon-alpha. We report the case of a 33-year-old Caucasian man who was successfully treated for acute hepatitis C with the combination of pegylated interferon-alpha2b and ribavirin, and who during treatment developed myopathy which proved reversible.

Adult↗
PubMed2000

Inhibition of basolateral cAMP permeability in the toad urinary bladder.

1. The effect of sulphonylurea drugs on hydrosmotic flow across toad urinary bladder epithelium was re-evaluated in the present study. Glibenclamide, added to the basolateral medium, significantly enhanced the osmotic flow induced by low doses of antidiuretic hormone (ADH) or forskolin (FK), while it inhibited the effect of exogenous cyclic adenosine monophosphate (cAMP) or its non-hydrolysable bromo derivative, 8-Br-cAMP, added to the basolateral medium. These opposite effects of glibenclamide on the transepithelial osmotic flow can be explained by a reduction of cAMP permeability across the basolateral membrane of the epithelium. The decrease in cAMP permeability leads, according to the direction of the cAMP gradient, to firstly an enhanced osmotic flow when cAMP is generated intracellularly by addition of ADH and FK, glibenclamide reducing cAMP exit from the cell, and secondly a decreased osmotic flow in response to cAMP (and 8-Br-cAMP) added to the basolateral medium, glibenclamide inhibiting, in this case, their entry into the cell. 2. The demonstration that glibenclamide actually inhibits the basolateral cAMP permeability rests on the fact that firstly it decreases the release of cAMP into the basolateral medium by about 40 %, at each concentration of ADH or forskolin tested, secondly it increases the cAMP content of paired hemibladders incubated in the presence of ADH or FK, when intracellular degradation was prevented by phosphodiesterase inhibition, and thirdly it decreases also the uptake of basolateral 8-Br-[3H]cAMP into paired toad hemibladders. 3. Taken together, the present data demonstrate that glibenclamide inhibits the toad urinary bladder basolateral membrane permeability to cAMP, most probably by a direct interaction with a membrane protein not yet indentified but distinct from the sulphonylurea receptor.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1999

P-glycoprotein inhibition by glibenclamide and related compounds.

Glibenclamide is well known to interact with the sulphonylurea receptor (SUR) and has been shown more recently to inhibit the cystic fibrosis transmembrane conductance regulator protein (CFTR), both proteins that are members of the ABC [adenosine 5'-triphosphate (ATP)-binding cassette] transporters. The effect of glibenclamide and two synthetic sulphonylcyanoguanidine derivatives (dubbed BM-208 and BM-223) was examined on P-glycoprotein, the major ABC transporter responsible for multidrug resistance (MDR) in cancer cells. To this end, we employed different cell lines that do or do not express P-glycoprotein, as confirmed by Western blotting: first, a tumour cell line (VBL600) selected from a human T-cell line (CEM) derived from an acute leukaemia; second, an epithelial cell line derived from a rat colonic adenocarcinoma (CC531(mdr+)) and finally, a non tumour epithelial cell line derived from the proximal tubule of the opossum kidney (OK). Glibenclamide and the two related derivatives inhibited P-glycoprotein because firstly, they acutely increased [3H]colchicine accumulation in P-glycoprotein-expressing cell lines only; secondly BM-223 reversed the MDR phenomenon, quite similarly to verapamil, by enhancing the cytotoxicity of colchicine, taxol and vinblastine and thirdly, BM-208 and BM-223 blocked the photoaffinity-labelling of P-glycoprotein by [3H]azidopine. Furthermore, glibenclamide is itself a substrate for P-glycoprotein, since the cellular accumulation of [3H]glibenclamide was low and substantially increased by addition of P-glycoprotein substrates (e. g., vinblastine and cyclosporine) only in the P-glycoprotein-expressing cell lines. We conclude that glibenclamide and two sulphonylcyanoguanidine derivatives inhibit P-glycoprotein and that sulphonylurea drugs would appear to be general inhibitors of ABC transporters, suggesting an interaction with some conserved motif.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1998

The Na+-I- cotransporter of the thyroid: characterisation of new inhibitors.

New inhibitors of the Na+-I- cotransporter of the thyroid in bovine thyroid slices and in bovine plasma membrane vesicles have been investigated. They include: (1) econazole; (2) 5-(N,N-hexamethylene)amiloride (HMA); and (3) dysidenin. In both systems, the kinetics of iodide transport yielded apparent Km values of 39 and 14 microM respectively. The possible interaction of each of these inhibitors with the iodide site of the Na+-I- cotransporter was tested by performing detailed transport kinetics analysis at varying iodide concentrations and at 150 mM NaCl. Econazole induced a non-competitive inhibition while dysidenin and HMA gave a mixed type of inhibition. The Ki values for dysidenin and econazole, computed from Dixon plots, were 5 and 2 microM respectively while the Ki value for HMA could not be determined. Each inhibition was reversible, indicating the absence of covalent binding of the inhibitor to the Na+-I- cotransporter.

Amiloride↗
PubMed1997

Hypothyroidism.

Explore the source record for details and available documents.

Cystic Fibrosis↗
PubMed1997

Expression of CFTR in human and bovine thyroid epithelium.

The expression of cystic fibrosis transmembrane conductance regulator (CFTR) in the thyroid has not been documented to date, although a role for CFTR in the thyroid follicular epithelium is suggested both clinically, by the occurrence of subclinical hypothyroidism in patients with cystic fibrosis (CF), and physiologically, by the presence of low-conductance, adenosine 3',5'-cyclic monophosphate-activated Cl channels in the follicular cells. Using reverse transcriptase-polymerase chain reaction with nested primers derived from exons 13 and 14 of the human CF gene, we have now documented the presence of CFTR mRNA in the human thyroid. Western blot analyses using six antibodies directed against different domains of human CFTR showed that a 165-kDa band was present in membrane extracts from bovine and human thyroid. This protein has the predicted size of mature CFTR and was not detected with preimmune serum or preadsorbed antiserum. By immunofluorescence and immunoperoxidase, CFTR was located in the follicular cells, with a diffuse, intracellular labeling pattern. Quantitative analysis revealed that 64% of the follicles were CFTR positive, but only 16% of the follicular cells were stained per follicle. The number of CFTR-positive cells was inversely proportional to the size of the follicle. These results 1) demonstrate the expression of CFTR at the mRNA and protein levels in human and bovine thyroid follicular cells and 2) suggest that CFTR expression could be instrumental in follicular enlargement.

Animals↗
PubMed1997

Acute hepatitis and drug-related lupus induced by minocycline treatment.

Minocycline is widely prescribed for long-term treatment in acne. Major side effects are rare and include hepatitis and drug-related lupus. Hepatitis can be early and acute or late and chronic, whereas lupus presents as a tardive and insidious disease. We report a case of minocycline-induced lupus initially presenting as acute hepatitis, evolving to chronic cytolysis, in a young man treated for facial acne.

Acne Vulgaris↗
PubMed1995

Methodology for assaying iodide conductance in proteoliposomes: specific induction by thyroid membrane protein.

A sensitive assay is developed to assess the existence of an iodide channel in a fraction of solubilized membrane proteins. This step is critical when considering various procedures for purification of this channel. Sodium cholate is used as a detergent as it does not denature the iodide channel. A simple and rapid method involving gel-filtration chromatography is used simultaneously to remove the detergent and to adjust the buffer composition, before protein insertion into liposomes. The presence of an iodide channel is investigated by measuring the iodide conductance of these proteoliposomes at 4 degrees C. An outward iodide gradient is set up across the proteoliposomal membrane by anion-exchange chromatography, allowing uptake of radiolabelled iodide. This uptake is conductive as it is abolished by valinomycin in the presence of potassium. It is specifically mediated by a thyroid plasma-membrane protein inserted into liposomes, as its denaturation before insertion totally abolished uptake. It was observed only within a well-defined fraction of thyroid membrane proteins collected by size-exclusion chromatography (molecular mass between 100 and 200 kDa). Furthermore, it was not observed with other membrane proteins such as ileal brush-border-membrane proteins or bacteriorhodopsin. Like many anion channels, this conductance was also inhibited by N-phenylanthranilic acid. Optimization of the assay is described, validating the measurement of conductive iodide uptake at 30 s by proteoliposomes reconstituted in a ratio of 10 micrograms of protein to 90 micrograms of lipid, with an outward iodide gradient (KI 15 mM inside and 1 microM outside). This assay provides a test of the biological activity of the iodide channel at each step of the purification; it can be applied to any anionic channel.

Animals↗
PubMed1995

The iodide channel of the thyroid. II. Selective iodide conductance inserted into liposomes.

An iodide channel has been previously identified in the plasma membrane of bovine throcytes [Golstein et al., Am. J. Physiol. 263 (Cell Physiol. 32): C590-C597, 1992]. The plasma membrane proteins were solubilized and ultrafiltered, and the protein fraction collected above 100 kDa was inserted in liposomes. Voltage-sensitive uptake of radiolabeled I- by these proteoliposomes was studied. To this end, an outward I- gradient was set up by loading the proteoliposomes with KI and removing extraliposomal I-. I- exit from the proteoliposome induces an inside positive membrane potential, which leads to the uptake of 125I- added to the incubation medium. This uptake was abolished by valinomycin, which in the presence of K+ short circuits the liposomal membrane potential, demonstrating the conductive nature of this uptake. A double reciprocal plot of I- influx over I- concentration suggests the existence of a single population of channels in these proteoliposomes with a Michaelis-Menten constant for I- of approximately 9 microM. When the proteoliposomes were loaded with KCl or KSCN instead of I-, no conductive uptake occurred anymore, suggesting that these anions are unable to diffuse through the I- conductance, hence do not generate a diffusion potential. I- uptake by KI-loaded proteoliposomes was not inhibited in the presence of a 1,000-fold excess of extraliposomal Cl- but was completely inhibited by a 1,000-fold excess of extraliposomal SCN-, indicating that Cl- does not permeate the I- channel, whereas SCN- inhibits it. SCN- and flufenamate were both shown to be competitive inhibitors of the I- channel with an inhibitor constant of approximately 10 and 750 microM, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗