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Articles 121 - 136 of 136

Full-Text Articles in Medical Neurobiology

Identifying Swelling-Activated Channels From Ion Selectivity Patterns, Dan R. Halm Sep 1998

Identifying Swelling-Activated Channels From Ion Selectivity Patterns, Dan R. Halm

Neuroscience, Cell Biology & Physiology Faculty Publications

No abstract provided.

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Direct Demonstration Of Retroviral Recombination In A Rhesus Monkey, Dawn P. Wooley, Randall A. Smith, Susan Czajak, Ronald C. Desrosiers Dec 1997

Direct Demonstration Of Retroviral Recombination In A Rhesus Monkey, Dawn P. Wooley, Randall A. Smith, Susan Czajak, Ronald C. Desrosiers

Neuroscience, Cell Biology & Physiology Faculty Publications

Recombination may be an important mechanism for increasing variation in retroviral populations. Retroviral recombination has been demonstrated in tissue culture systems by artificially creating doubly infected cells. Evidence for retroviral recombination in vivo is indirect and is based principally on the identification of apparently mosaic human immunodeficiency virus type 1 genomes from phylogenetic analyses of viral sequences. We infected a rhesus monkey with two different molecularly cloned strains of simian immunodeficiency virus. One strain of virus had a deletion in vpx and vpr, and the other strain had a deletion in nef. Each strain on its own induced low virus …

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A Recombinant Inwardly Rectifying Potassium Channel Coupled To Gtp-Binding Proteins, Kim W. Chan, M. Noelle Langan, Jin Liang Sui, J. Ashot Kozak, Amanda Pabon, John A. A. Ladias, Diomedes E. Logothetis Mar 1996

A Recombinant Inwardly Rectifying Potassium Channel Coupled To Gtp-Binding Proteins, Kim W. Chan, M. Noelle Langan, Jin Liang Sui, J. Ashot Kozak, Amanda Pabon, John A. A. Ladias, Diomedes E. Logothetis

Neuroscience, Cell Biology & Physiology Faculty Publications

GTP-binding (G) proteins have been shown to mediate activation of inwardly rectifying potassium (K+) channels in cardiac, neuronal and neuroendocrine cells. Here, we report functional expression of a recombinant inwardly rectifying channel which we call KGP (or hpKir3.4), to signify that it is K+ selective, G-protein-gated and isolated from human pancreas. KGP expression in Xenopus oocytes resulted in sizeable basal (or agonist-independent) currents while coexpression with a G-protein-linked receptor, yielded additional agonist-induced currents. Coexpression of KGP and hGIRK1 (a human brain homolog of GIRK1/Kir3.1) produced much larger basal currents than those observed with KGP or hGIRK1 alone, and upon coexpression …

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Gtpase-Deficient G Alpha 16 And G Alpha Q Induce Pc12 Cell Differentiation And Persistent Activation Of Cjun Nh2-Terminal Kinases., Lynn E. Heasley, Brooke Storey, Gary R. Fanger, Laura Butterfield, J Zamarripa, D Blumberg, R A. Maue Feb 1996

Gtpase-Deficient G Alpha 16 And G Alpha Q Induce Pc12 Cell Differentiation And Persistent Activation Of Cjun Nh2-Terminal Kinases., Lynn E. Heasley, Brooke Storey, Gary R. Fanger, Laura Butterfield, J Zamarripa, D Blumberg, R A. Maue

Dartmouth Scholarship

Persistent stimulation of specific protein kinase pathways has been proposed as a key feature of receptor tyrosine kinases and intracellular oncoproteins that signal neuronal differentiation of rat pheochromocytoma (PC12) cells. Among the protein serine/threonine kinases identified to date, the p42/44 mitogen-activated protein (MAP) kinases have been highlighted for their potential role in signalling PC12 cell differentiation. We report here that retrovirus-mediated expression of GTPase-deficient, constitutively active forms of the heterotrimeric Gq family members, G alpha qQ209L and G alpha 16Q212L, in PC12 cells induces neuronal differentiation as indicated by neurite outgrowth and the increased expression of voltage-dependent sodium channels. Differentiation …

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Effects Of Natural Sequence Variation On Recognition By Monoclonal Antibodies Neutralize Simian Immunodeficiency Virus Infectivity, Weon Sang Choi, Catherine Collignon, Clotilde Thiriart, Dawn P. Wooley, E. J. Scott, Karen A. Kent, Ronald C. Desrosiers Sep 1994

Effects Of Natural Sequence Variation On Recognition By Monoclonal Antibodies Neutralize Simian Immunodeficiency Virus Infectivity, Weon Sang Choi, Catherine Collignon, Clotilde Thiriart, Dawn P. Wooley, E. J. Scott, Karen A. Kent, Ronald C. Desrosiers

Neuroscience, Cell Biology & Physiology Faculty Publications

The determinants of immune recognition by five monoclonal antibodies (KK5, KK9, KK17, Senv7.1, and Senv101.1) that neutralize simian immunodeficiency virus infectivity were analyzed. These five neutralizing monoclonal antibodies were generated to native SIVmac251 envelope glycoprotein expressed by a vaccinia virus recombinant vector. All five recognize conformational or discontinuous epitopes and require native antigen for optimal recognition. These monoclonal antibodies also recognize SIVmac239 gp120, but they do not recognize gp120 of two natural variants of SIVmac239, 1-12 and 8-22, which evolved during the course of persistent infection in vivo (D.P.W. Burns and R.C. Desrosiers, J. Virol. 65:1843-1854, 1991). Recombinant viruses which …

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High Rates Of Frameshift Mutations Within Homo-Oligomeric Runs During A Single Cycle Of Retroviral Replication, Dawn P. Wooley, H. M. Temin Jul 1994

High Rates Of Frameshift Mutations Within Homo-Oligomeric Runs During A Single Cycle Of Retroviral Replication, Dawn P. Wooley, H. M. Temin

Neuroscience, Cell Biology & Physiology Faculty Publications

Homo-oligomeric runs were inserted into a spleen necrosis virus-based retrovirus vector to determine the nature and rate of mutations within runs of 10 to 12 identical nucleotides during a single replication cycle. Clones of helper cells containing integrated copies of retroviral vectors were used to produce virus for infection of target (nonhelper) cells. Proviral sequences from target cell clones were compared with proviral sequences from helper cell clones to study mutations that occurred during a single cycle of replication. In addition to the internal region spanning the homo-oligomeric inserts, a naturally occurring run of 10 T's in the long terminal …

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Simian Immunodeficiency Virus Mutants Resistant To Serum Neutralization Arise During Persistent Infection Of Rhesus Monkeys, Dawn P. Wooley, Catherine Collignon, Ronald C. Desrosiers Jul 1993

Simian Immunodeficiency Virus Mutants Resistant To Serum Neutralization Arise During Persistent Infection Of Rhesus Monkeys, Dawn P. Wooley, Catherine Collignon, Ronald C. Desrosiers

Neuroscience, Cell Biology & Physiology Faculty Publications

We previously described the pattern of sequence variation in gp120 following persistent infection of rhesus monkeys with the pathogenic simian immunodeficiency virus SIVmac239 molecular clone (D.P.W. Burns and R.C. Desrosiers, J. Virol. 65:1843, 1991). Sequence changes were confined largely to five variable regions (V1 to V5), four of which correspond to human immunodeficiency virus type 1 (HIV-1) gp120 variable regions. Remarkably, 182 of 186 nucleotide substitutions that were documented in these variable regions resulted in amino acid changes. This is an extremely nonrandom pattern, which suggests selective pressure driving amino acid changes in discrete variable domains. In the present study, …

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Gelatinase Activity In The Mouse Uterus During Early Pregnancy, Carol A. Brenner, Richard R. Adler, Gary L. Nieder Sep 1992

Gelatinase Activity In The Mouse Uterus During Early Pregnancy, Carol A. Brenner, Richard R. Adler, Gary L. Nieder

Neuroscience, Cell Biology & Physiology Faculty Publications

No abstract provided.

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Anion Permeation In An Apical Membrane Chloride Channel Of A Secretory Epithelial Cell, Dan R. Halm, Raymond A. Frizzell Mar 1992

Anion Permeation In An Apical Membrane Chloride Channel Of A Secretory Epithelial Cell, Dan R. Halm, Raymond A. Frizzell

Neuroscience, Cell Biology & Physiology Faculty Publications

Single channel currents though apical membrane Cl channels of the secretory epithelial cell line T84 were measured to determine the anionic selectivity and concentration dependence of permeation. The current-voltage relation was rectified with single channel conductance increasing at positive potentials. At 0 mV the single channel conductance was 41 ± 2 pS. Permeability, determined from reversal potentials, was optimal for anions with diameters between 0.4 and 0.5 nm. Anions of larger diameter had low permeability, consistent with a minimum pore diameter of 0.55 nm. Permeability for anions of similar size was largest for those ions with a more symmetrical charge …

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Strain-Specific Neutralizing Determinant In The Transmembrane Protein Of Simian Immunodeficiency Virus, Toshiaki Kodama, Dawn P. Wooley, Daniel P. Silva, Fulvia Dimarzo Veronese, Ronald C. Desrosiers Apr 1991

Strain-Specific Neutralizing Determinant In The Transmembrane Protein Of Simian Immunodeficiency Virus, Toshiaki Kodama, Dawn P. Wooley, Daniel P. Silva, Fulvia Dimarzo Veronese, Ronald C. Desrosiers

Neuroscience, Cell Biology & Physiology Faculty Publications

Monoclonal antibody SF8/5E11, which recognizes the transmembrane protein (TMP) of simian immunodeficiency virus of macaque monkeys (SIVmac), displayed strict strain specificity. It reacted with cloned and uncloned SIVmac251 but not with cloned SIVmac142 and SIVmac239 on immunoblots. This monoclonal antibody neutralized infection by cloned, cell-free SIVmac251 and inhibited formation of syncytia by cloned SIVmac251-infected cells; these activities were specific to cloned SIVmac251 and did not occur with the other viruses. Site-specific mutagenesis was used to show that TMP amino acids 106 to 110 (Asp-Trp-Asn-Asn-Asp) determined the strain specificity of the monoclonal antibody. This strain-specific neutralizing determinant is located within a …

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Selection Of Genetic Variants Of Simian Immunodeficiency Virus In Persistently Infected Rhesus Monkeys, Dawn P. Wooley, Ronald C. Desrosiers Apr 1991

Selection Of Genetic Variants Of Simian Immunodeficiency Virus In Persistently Infected Rhesus Monkeys, Dawn P. Wooley, Ronald C. Desrosiers

Neuroscience, Cell Biology & Physiology Faculty Publications

Genetic and antigenic variation may be one means by which lentiviruses that cause AIDS avoid elimination by host immune responses. Genetic variation in the envelope gene (env) was studied by comparing the nucleotide sequences of 27 clones obtained from two rhesus monkeys infected with molecularly cloned simian immunodeficiency virus. All 27 clones differed from each other and differed from the input clone in the gp120 (SU) portion of the envelope gene. Nucleotide substitutions were shown to accumulate with time at an average rate of 8.5 per 1,000 per year in SU. Surprisingly, the majority of nucleotide substitutions (81%) resulted in …

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Significance Of Premature Stop Codons In Env Of Simian Immunodeficiency Virus, Toshiaki Kodama, Dawn P. Wooley, Yathirajulu M. Naidu, Harry W. Kestler Iii, Muthiah D. Daniel, Yen Li, Ronald C. Desrosiers Nov 1989

Significance Of Premature Stop Codons In Env Of Simian Immunodeficiency Virus, Toshiaki Kodama, Dawn P. Wooley, Yathirajulu M. Naidu, Harry W. Kestler Iii, Muthiah D. Daniel, Yen Li, Ronald C. Desrosiers

Neuroscience, Cell Biology & Physiology Faculty Publications

The location of the translational termination codon for the transmembrane protein (TMP) varies in three infectious molecular clones of simian immunodeficiency virus from macaques (SIVmac). The SIVmac251 and SIVmac142 infectious clones have premature stop signals that differ in location by one codon; transfection of these DNAs into human HUT-78 cells yielded virus with a truncated TMP (28 to 30 kilodaltons [kDa]). The SIVmac239 infectious clone does not have a premature stop codon in its TMP-coding region. Transfection of HUT-78 cells with this clone initially yielded virus with a full-length TMP (41 kDa). …

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Aldosterone Stimulates K Secretion Across Mammalian Colon Independent Of Na Absorption, Gerhard Rechkemmer, Dan R. Halm Jan 1989

Aldosterone Stimulates K Secretion Across Mammalian Colon Independent Of Na Absorption, Gerhard Rechkemmer, Dan R. Halm

Neuroscience, Cell Biology & Physiology Faculty Publications

K transport across guinea pig (Cavia porcellus) distal colon was measured in vitro using isotopically determined unidirectional fluxes. Aldosterone stimulated electrogenic Na absorption, as measured by amiloride-sensitive short-circuit current (Isc), and reduced net K absorption from +2.5 ± 0.2 µEq/cm2 per hr to +0.8 ± 0.3 µEq/cm2 per hr (mean ± SEM). Amiloride addition to the mucosal solution did not enhance net K absorption, as expected if inhibiting active Na absorption would reduce active K secretion as in the distal nephron. The amiloride-insensitive Isc was -1.0 ± 0.2 µEq/cm2 per hr (mean ± SEM) …

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Electrophysiology Of Flounder Intestinal Mucosa. I. Conductance Properties Ofthe Cellular And Paracellular Pathways, Dan R. Halm, Edward J. Krasny Jr., Raymond A. Frizzell Jun 1985

Electrophysiology Of Flounder Intestinal Mucosa. I. Conductance Properties Ofthe Cellular And Paracellular Pathways, Dan R. Halm, Edward J. Krasny Jr., Raymond A. Frizzell

Neuroscience, Cell Biology & Physiology Faculty Publications

We evaluated the conductances for ion flow across the cellular and paracellular pathways of flounder intestine using microelectrode techniques and ion-replacement studies. Apical membrane conductance properties are dominated by the presence of Ba-sensitive K channels. An elevated mucosal solution K concentration, [K]m, depolarized the apical membrane potential (ψa) and, at [K]m less than 40 mM, the K dependence of ψa was abolished by 1-2 mM mucosal Ba. The basolateral membrane displayed Cl conductance behavior, as evidenced by depolarization of the basolateral membrane potential (ψb) with reduced serosal Cl concentrations, [Cl]s. …

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Electrophysiology Of Flounder Intestinal Mucosa. Ii. Relation Of The Electrical Potential Profile To Coupled Nacl Absorption, Dan R. Halm, Edward J. Krasny Jr., Raymond A. Frizzell Jun 1985

Electrophysiology Of Flounder Intestinal Mucosa. Ii. Relation Of The Electrical Potential Profile To Coupled Nacl Absorption, Dan R. Halm, Edward J. Krasny Jr., Raymond A. Frizzell

Neuroscience, Cell Biology & Physiology Faculty Publications

We characterized the hyperpolarization of the electrical potential profile of flounder intestinal cells that accompanies inhibition of NaCl cotransport. Several observations indicate that hyperpolarization of ψa and ψb (Δψa,b) results from inhibition of NaCl entry across the apical membrane: (a) the response was elicited by replacement of mucosal solution Cl or Na by nontransported ions, and (b) mucosal bumetanide or serosal cGMP, inhibitors of NaCl influx, elicited Δψa,b and decreased the transepithelial potential (ψt) in parallel. Regardless of initial values, ψa and ψb approached the equilibrium potential for K (EK …

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Metabolism In Preimplantation Mouse Embryos, Harry M. Weitlauf, Gary L. Nieder Jul 1984

Metabolism In Preimplantation Mouse Embryos, Harry M. Weitlauf, Gary L. Nieder

Neuroscience, Cell Biology & Physiology Faculty Publications

The ability of preimplantation mouse embryos to utilize glucose oxidatively is controlled, in part at least, at the level of glycolysis. Various experimental observations are reviewed that indicate the regulatory mechanism in delayed implanting blastocysts involves the classic negative allosteric feedback of high levels of ATP on phosphofructokinase while the situation in 2-cell embryos appears to be more complicated. That is, in addition to the usual negative effect of ATP and citrate on phosphofructokinase, there appears to be a modification of hexokinase that prevents phosphorylation of adequate amounts of glucose and results in low levels of fructose-6-phosphate at the 2-cell …

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