Search PubMed⌕ Search

Biomedical subjects

A Leibstein

Publications and source records attributed to A Leibstein.

6 recordsLinked to original sources
PubMed1985

A fast screening method for histochemical localization of carbonic anhydrase. Application to kidney, skeletal muscle, and thrombocytes.

A simple method for histochemical localization of carbonic anhydrase using 5-dimethyl-amino-naphthalene-1-sulfonamide (DNSA) is described. Cryosections of tissues, or cell smears, are incubated in 3 to 10 X 10(-5) M DNSA and viewed in a fluorescence microscope. Upon excitation with ultraviolet light, sites of carbonic anhydrase localization can be identified by an intense blue fluorescence, which is due to the emission of blue light (lambda max = 470 nm) by carbonic anhydrase-DNSA complexes. This fluorescence can be largely suppressed by simultaneous incubation with 1 X 10(-4) to 2 X 10(-3) M concentrations of nonfluorescent carbonic anhydrase inhibitors, displacing DNSA from its binding site on the enzyme. Application of the method to kidney, skeletal muscle, and thrombocytes yields patterns of carbonic anhydrase localization that are in good agreement with results that have been obtained with a variety of other techniques.

Animals↗
PubMed1984

Gap junctions in several tissues share antigenic determinants with liver gap junctions.

Using affinity-purified antibodies against mouse liver gap junction protein (26 K), discrete fluorescent spots were seen by indirect immunofluorescence labelling on apposed membranes of contiguous cells in several mouse and rat tissues: pancreas (exocrine part), kidney, small intestine (epithelium and circular smooth muscle), Fallopian tube, endometrium, and myometrium of delivering rats. No reaction was seen on sections of myocardium, ovaries and lens. Specific labelling of gap junction plaques was demonstrated by immunoelectron microscopy on ultrathin frozen sections through liver and the exocrine part of pancreas after treatment with gold protein A. Weak immunoreactivity was found on the endocrine part of the pancreas (i.e., Langerhans islets) after glibenclamide treatment of mice and rats, which causes an increase of insulin secretion and of the size as well as the number of gap junction plaques in cells of Langerhans islets. Furthermore, the affinity purified anti-liver 26 K antibodies were shown by immunoblot to react with proteins of similar mol. wt. in pancreas and kidney membranes. Taken together these results suggest that gap junctions from several, morphogenetically different tissues have specific antigenic sites in common. The different extent of specific immunoreactivity of anti-liver 26 K antibodies with different tissues is likely due to differences in size and number of gap junctions although structural differences cannot be excluded.

Animals↗
PubMed1983

Immunocytochemical localization of the gap junction 26 K protein in mouse liver plasma membranes.

Specific binding sites for anti-26 K antibodies directed against the liver gap junction protein (26 K) were localized by immunoelectron microscopy in gap junction plaques purified from hepatic plasma membranes. Using immunofluorescence microscopy we found discrete fluorescent spots on plasma membranes in cross sections of liver tissues after incubation with anti-26 K antibodies. This is consistent with the notion of specific binding to gap junction plaques. Quantitative binding of anti-26 K antibodies was indirectly measured by the protein A-gold technique. We found that urea/detergent-treated, purified gap junction plaques bind 30-fold more anti-26 K antibodies than preimmune serum. Anti-26 K antibodies also bind specifically to native gap junction plaques within hepatic plasma membranes although only about one fifth as efficiently as to purified plaques. Possibly the anti-26 K antibodies raised after injection of SDS-denatured 26 K protein into rabbits recognize the cytoplasmic face of urea/detergent-treated plaques better than that of native plaques. Some, if not most, of the vesicular structures in preparations of purified plaques appear to be derived from split gap junction plaques and are probably sheets of gap junction hemichannels. In some vesicles the former cytoplasmic face of the hemichannels is turned outside, other vesicles have the former cell surface turned outside. The anti-26 K antibodies do not recognize any 26 K protein on the sheets of partially split gap junction plaques, on the heterogeneous vesicular structures, or on non-junctional areas of hepatic plasma membranes. These results suggest that the conformation of the 26 K protein in plaques must be different from that of the 26 K protein in earlier biosynthetic steps of plaque assembly.

Animals↗
PubMed1978

The oligodendrocytic junctional complex.

The junctional complex of oligodendrocytes was studied by means of different electron microscopical techniques. This complex is composed of the following junctional membrane formations: 1) tight junctional domains in the oligodendrocytic membrane near the some of the cells, 2) fasciae occludentes or focal tight junctions on the outer oligodendrocytic loop of myelin and on the outermost myelin membrane, 3) gap junctions of considerable size variations, either on membranes near the soma or on peripheral oligodendrocytic processes, and 4) non-paranodal transverse bands. The different types of oligodendrocytic junctions are discussed in terms of their functional implications.

Animals↗