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J Wietzerbin

Publications and source records attributed to J Wietzerbin.

At least 109 records · Page 6Linked to original sources
PubMed1985

Delineation of three subsets of class I human T antigens (HTA) on Molt-4 cells: serologic and regulatory relationship to HLA class I antigens.

Three subsets of class I human T antigens (HTA) were serologically identified on the surface of the Molt-4 T lymphoma cell line. The HTA 1 subset is defined by NAI/34, D47, or 10H3.9 cross-reactive m.Ab. and by BL6 m.Ab. The HTA 2 and HTA 3 subsets are defined by M241 and 4A7.6 m.Ab., respectively. We obtained no evidence of any additional HTA subset. The different HTA antigens share only few epitopes with human leukocyte antigens (HLA-A, -B, and -C). Interestingly, these epitopes all belong to the same cluster defined on HLA class I molecules, but differ from one HTA subset to another. These results would therefore suggest that HTA and HLA class I antigens display a limited structural homology, but have a conserved epitopic area whose detailed structure differs for each HTA subset. Furthermore, the cell surface expression of each HTA class I molecule type is differently enhanced by natural interferon (IFN)-alpha or -gamma. This result additionally supports the serologic delineation of HTA subsets, and suggests that the corresponding genes in Molt-4 cells, are subjected to distinct regulations.

Animals↗
PubMed1984

Synergistic protection by specific antibodies and interferon against infection by Trypanosoma cruzi in vitro.

Trypanosoma cruzi infects many mammalian cell types in vitro, including fibroblasts and macrophages. We have analyzed and compared the infection of mouse 3T3 fibroblasts and J774 macrophage-like tumor cells by cloned Y-A1.2 T. cruzi trypomastigotes. The effects of T. cruzi-specific antibodies and of interferon (IFN) on infection were considered. Specific antibodies protected 3T3 fibroblasts from infection by T. cruzi, but increased the relative infectivity for J774 cells due to binding of the opsonized parasite to J774 Fc receptors. It was also apparent that IFN-alpha, beta (produced by fibroblasts) and IFN-gamma (produced by T lymphocytes) activated trypanocidal activities in both 3T3 and J774 cells, although IFN-gamma was 100 to 2000 times more effective than IFN-alpha, beta on the basis of IFN antiviral units added per culture. When anti-T. cruzi antibodies and IFN-alpha, beta or IFN-gamma were used jointly, a synergistic protective effect was observed with both 3T3 fibroblasts and J774 cells. These results suggest that B and T lymphocytes might collaborate in vivo in the protection against T. cruzi infections by the production of anti-trypomastigote antibodies and IFN-gamma, respectively.

Animals↗
PubMed1984

Cellular pH and the ADH-induced hydrosmotic response in different ADH target epithelia.

The hydrosmotic response elicited by oxytocin in the frog skin epithelium (Rana esculenta) was reversibly inhibited by 70% when the medium pH was reduced to 6.2 by CO2 bubbling on the serosal side. On the contrary, the response to 8-bromo cyclic AMP (8 Br-CAMP) was not affected by medium acidification, even after corion removal. In other experiments intracellular pH was measured, employing the dimetyl-oxazolidine-dione distribution technique, in frog urinary bladder and the isolated frog skin epithelium. As previously observed in the case of oxytocin, 8 Br-CAMP increased intracellular pH in frog urinary bladder. Incubation with oxytocin also augmented the intracellular pH in the isolated frog skin epithelium but 8 Br-CAMP did not modify cell proton concentration in this tissue. From previous and present results it can be summarized that: 1) The intracellular alkalinization effect elicited by oxytocin addition and the inhibition in the hydrosmotic response induced by medium acidification were qualitatively similar in both tested target epithelia. 2) On the contrary, a post cyclic AMP step sensitive to changes in intracellular pH was not observed in frog skin, as is the case in frog urinary bladder. 3) The 8 Br-CAMP induced intracellular alkalinization effect was only observed in frog urinary bladder.

Animals↗
PubMed1984

Studies on purification of human gamma interferon: chromatographic behavior of accompanying IL2 and B-cell helper activity.

Gamma interferon (gamma IFN) was produced in human lymphocyte cultures stimulated by PHA. Titers were in the range of 10,000-30,000 U/ml. Crude gamma IFN was adsorbed on silicic acid, from which the antiviral activity was eluted by a buffer containing a high salt concentration and ethylene glycol. This treatment allowed quantitative recovery of gamma IFN with a specific activity of 5 X 10(5)-1 X 10(6) U/mg of proteins. IL2 and B-cell helper activities were adsorbed and eluted from silicic acid together with the antiviral activity. This finding might be of practical interest for the purification of these lymphokines, particularly IL2. Gamma interferon was further purified on Blue Sepharose to a specific activity of 2 X 10(7) U/mg. The resulting preparations still contained IL2 and B cell helper activities. However, taking advantage of the differences in apparent hydrophobicity and in isoelectric point, we were able to dissociate antiviral activity from lymphokines. Such dissociation should facilitate the study of the biological properties of human natural gamma IFN.

Adsorption↗
PubMed1984

The onset and offset of the hydrosmotic response in frog epithelia.

The onset and offset of the hydrosmotic responses elicited by different agonists in frog urinary bladder, frog skin and isolated frog skin epithelium were studied and compared. The removal of the frog skin supporting layers accelerated the onset of the reactions to oxytocin and 8-bromo-cyclic AMP (8-Br-cAMP), which, however, remained slower than the onset in the urinary bladder. The offset of these actions was not affected by corion removal and was also slower than in the bladder. A marked asymmetry between onset and offset of the hydrosmotic response was observed when the isolated skin epithelium was stimulated with 8-Br-cAMP. The results show that the increases in water permeability elicited by oxytocin and cyclic-AMP derivatives in frog skin and frog urinary bladder, although attributable to the same general mechanisms, present different specific characteristics.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1983

Expression of Ia antigens by cultured astrocytes treated with gamma-interferon.

The expression of major histocompatibility complex class II or Ia antigens by neural cells has been investigated by indirect immunofluorescence on dissociated cultures from mouse cerebellum, cerebral cortex and dorsal root ganglia. Ia antigen expression was not detectable under standard culture conditions. However, treatment of mixed cultures from the cerebellum and of astrocyte cultures from the cerebral cortex with gamma-interferon preparations induced expression of Ia antigens on a fraction of the astrocytes. Under the same conditions, Ia+ cells could be observed in dorsal root ganglion cultures.

Animals↗
PubMed1983

Action of different gamma interferons on mouse leukemic cells resistant to alpha and beta interferons.

Phytohemagglutinin-induced interferon-gamma (IFN-gamma) was reported to act on mouse leukemic L1210 R cells resistant to IFN-alpha and -beta. Results reported here show that these cells are also sensitive to various preparations of murine IFN-gamma derived from different sources and purified to different degrees and that lymphokines present in the preparations are not involved in the antiviral effect of IFN. In addition, IFN-gamma preparation increases concanavalin A binding to L1210 S and L1210 R cells indicating that the sensitivity of L1210 R cells to IFN-gamma is not limited to its antiviral effect.

Animals↗
PubMed1983

Intracellular pH, transepithelial pH gradients, and ADH-induced water channels.

Urinary bladders of frogs were exposed to a transepithelial proton and osmotic gradient (serosal pH 8.1, Tris or bicarbonate buffer; mucosal pH 5.8, unbuffered) while the alkalinization rate of the mucosal bath and the net water movement were simultaneously monitored. It was observed that 1) the mucosal alkalinization rate was dependent on serosal pH and buffer; 2) oxytocin increased the mucosal alkalinization rate only when serosal bicarbonate was employed, whereas the net water movement augmented both when serosal bicarbonate or Tris buffers were used; 3) amiloride did not modify the mucosal alkalinization rate either before or after oxytocin; 4) the increases in the mucosal alkalinization rate and in the net water movement induced by oxytocin (serosal bicarbonate) were negatively correlated. In other experiments intracellular pH (pHi) was estimated with the DMO distribution technique with the following results. 1) Oxytocin increased the pHi when either serosal bicarbonate or Tris buffers was used and even in the presence of a low mucosal pH (Tris buffer, pH 5.8). 2) Important cellular acidification was observed when CO2 was bubbled (to pH 5.8), whereas the hydrosmotic response to 8-bromo-cAMP was clearly inhibited. These results indicate that cellular alkalinization could play a pivotal role in action of ADH, show that ADH can modify the transepithelial pH equilibrium mechanism, and suggest that intracellular pH regulation and water permeability control can be linked regulatory processes.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1982

Microelectrode studies of the effect of lanthanum on the electrical potential and resistance of outer and inner cell membranes of isolated frog skin.

Microelectrodes were used to investigate the effect of 0.5 mM mucosal lanthanum (La3+) on the intracellular potential and the resistance of outer and inner isolated frog skin (Rana esculenta) cell membranes. Under short-circuit conditions, the transapical membrane potential Vsco (mean value = -65.4 +/- 3.2 mV, inside negative) hyperpolarized to -108.7 +/- 2.3 mV in control skins, after addition of the sodium blocker amiloride. Current-voltage curves for the outer and inner membranes were constructed from the amiloride-inhibitable current versus the outer membrane potential Vo or the inner membrane potential Vi. The outer, and to a lesser degree the inner, membrane showed a characteristic nonlinearity with two slope resistances. Addition of La3+ to the outer medium increased the short-circuit current to 190% of the control value. Vsco concomitantly changed to -28 +/- 3.5 mV and outer and inner membrane resistances fell, considerably attenuating the nonlinearity seen in control skins. La3+ is suggested to raise the conductance by its effect on the surface potential. A secondary long-term inhibitory effect of La3+ on short-circuit current has been observed. It is ascribed to the penetration of La3+ into the sodium channels.

Animals↗
PubMed1982

Induction of interferon by mycoplasmas in mouse spleen cell cultures.

Interferon production in cocultures between lymphoma cells and lymphocytes was previously found to be caused by mycoplasma contamination of the tumor cells. Here we have shown that M. arginini caused interferon production in spleen cells of C57BL/6 mice. The producer cell in spleen cell cultures was insensitive to treatment with anti-theta serum plus complement and it was present in spleen cell cultures of homozygous nude mice. Macrophage depletion did not adversely affect interferon production whereas interferon production was abolished in cultures of cells obtained after passage through nylon wool columns. Collectively, these data suggest, but cannot definitively prove that interferon is produced by B cells. By the use of specific antisera it was found that by all probability the interferon produced represented interferon alpha.

Animals↗
PubMed1982

Chromatographic behavior, purification, and properties of mouse BCG-induced gamma interferon.

Mouse gamma antigen-induced interferon (IFN) was produced in vivo by injecting PPD into BCG-sensitized mice. The IFN activity present in the serum was partially purified by adsorption on silicic acid and elution with buffer containing ethylene glycol, followed by chromatography of the eluate on Blue-Trisacryl. This method yielded IFN preparations with a specific activity of 1.5 x 10(5) mu/mg protein (10,000-fold purification). BCG IFN showed high affinity for polynucleotides and apparent hydrophobicity, two characteristics which allowed it to bind to Poly I agarose and Phenyl Sepharose, respectively. The chromatographic behavior of BCG IFN on Con A Sepharose indicates that BCG IFN is glycosylated. However, binding of the antiviral activity to the lectin column was only possible when purified IFN was used for chromatography. Although the purification method described here allowed purification of the antiviral activity as a major fraction, molecular heterogeneity was detected under certain chromatographic conditions. Two fractions with different molecular weights of 27,000 and 56,000, respectively, were always obtained by sieving purified BCG IFN on Sephacryl S 200.

Animals↗
PubMed1980

Studies on Brucella interferon: chromatographic behaviour and purification.

Interferon was induced by infecting mice with Brucella suis. Serum containing interferon activity was analyzed by chromatography on Concanavalian A-Sepharose and Phenyl-Sepharose CL-4B columns. Antiviral activity was completely retained by the lectin column indicating that all the interferon molecules are glycosylated. The chromatographic behaviour of Brucella interferon on Phenyl-Sepharose CL-4B shows that, like other interferons, Brucella displays hydrophobic properties. However, the hydrophobicity of the interferon molecule was masked in the crude preparation and was only detectable when purified Brucella interferon was used for chromatography. The antigenic properties of Brucella interferon provided the means for developing an affinity chromatographic method resulting in about 60,000 fold purification. As in the case of viral interferon, treatment of L cells with Brucella interferon induced specific enhanced in vitro phosphorylation of a 67,000 molecular weight protein after incubation of cell extracts with double-stranded RNA and [gamma-32P] ATP.

Adenosine Triphosphate↗
PubMed1980

Production of antibodies against mouse immune T (type II) interferon and their neutralizing properties.

An antiserum to immune T-type mouse interferon was prepared in rabbits by repeated injections of interferon, induced by phytohaemagglutinin (PHA) in mouse spleen cells and purified to 1 X 10(5) units/mg protein. The antiserum neutralized mouse interferons synthesized in vitro in response to several T mitogens and Brucella organisms, and also the type II interferon present in the serum of BCG-sensitized mice after an injection of the specific antigen, tuberculin. All these interferons are thus antigenically related; they are also all unstable at pH 2. In contrast, the antiserum did not neutralize interferons induced by West Nile virus (WNV) and Newcastle disease virus (NDV) in vitro, or by lipopolysaccharide and Brucella organisms in vivo; all these interferons are stable at pH 2. It also failed to neutralize a non-glycosylated virus interferon prepared in the presence of tunicamycin.

Animals↗
PubMed1979

Effects of mucosal lanthanum on electrical parameters of isolated frog skin. Mechanism of action.

The effect of mucosal La3+ on electrical parameters of isolated frog skins was studied on isolated frog skins with normally polarized or depolarized apical membrane. La3+ increases R8, the paracellular or shunt resistance and diminishes RNa, the resistance of the active sodium path, in both polarized and depolarized skins. The stimulatory effect of La3+ on short-circuit current (Is.c.) is correlated with this decrease in RNa. The characteristics of the stimulatory effect are: very rapid onset, ionic strength dependency, the possibility of being elicited by many other ions besides La3+. These features allow us to postulate that La3+ might affect the external interfacial potential which in turn affects the resistance of the sodium path.

Animals↗