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R Wang

Publications and source records attributed to R Wang.

At least 469 records · Page 26Linked to original sources
PubMed1996

Protein partition between the different phases comprising poly(ethylene glycol)-salt aqueous two-phase systems, hydrophobic interaction chromatography and precipitation: a generic description in terms of salting-out effects.

The solution behaviour of selected proteins has been studied under conditions promoting precipitation, binding to mildly hydrophobic adsorbents or partition. Solvophobic theory may be used to describe these forms of protein partition. The tendency of a protein to partition therein is dependent upon surface properties of the protein solute mediated by the concentration and nature of added salts. As applied to partitioning in poly(ethylene glycol) (PEG)-salt systems this implies that linear (Brönsted) relationships apply only to proteins partitioned close to the critical point. At longer tie-line lengths protein partitioning is increasingly influenced by salting-out forces. This is confirmed by the observed behaviour of the proteins. The point at which this behaviour changes has been unambiguously defined enabling the direct comparison of phase transition of proteins during partition in all systems. The results obtained show that phase transition during adsorption and partition occur at similar concentrations of salt. This is less than that required to promote precipitation. It appears, from these limited studies, that top-phase preferring proteins are partitioned at salt concentrations above those required to cause adsorption. Proteins preferring the lower phase are partitioned at salt concentrations close to or below those required for adsorption. This raises questions regarding the solvated molecular form of the partitioned proteins and the definition of the partition coefficient.

Chemical Precipitation↗
PubMed1996

Modulation of K+ channel currents by serum amineoxidase in neurons.

The influence of bovine serum amineoxidase (SAO), a circulating copper-enzyme, on neuronal K+ channels is described. Bovine SAO enhanced K+ channel currents in N1E-115 neuroblastoma cells in a time-dependent manner. Unlike ceruloplasmin (another copper-protein, shown as depolarizing factor in neurons), SAO had no effect on resting potential of neurons. However, pretreatment of cells with SAO inhibited ceruloplasmin-induced membrane depolarization. Although ceruloplasmin alone inhibited K+ channel currents, it further enhanced K+ channel currents in the presence of SAO. Therefore, SAO may be another endogenous modulator of neuronal K+ channels with effect and mechanisms different from those of ceruloplasmin.

Amine Oxidase (Copper-Containing)↗
PubMed1996

Purification of single-stranded M13 DNA by cooperative triple-helix-mediated affinity capture.

A solid-phase triple-helix-mediated affinity capture method is described for the purification of single-stranded M13 DNA for use as template in fluorescence-based DNA sequencing reactions. In this method, a biotinylated polypyrimidine oligonucleotide "loop" bound to streptavidin-coated magnetic beads is used to selectively capture single-stranded M13 DNA from high-titer phage supernatant through the formation of a cooperative triple helix (CTH) complex between the oligonucleotide and a polypurine site previously cloned into the M13 vector. Capture is accomplished at acidic pH to encourage triple-helix formation, while elution is performed at alkaline pH with heating to destroy the CTH complex. The beads can be reused up to three times without probe replenishment. Yields of M13 ssDNA in excess of 1 microgram per milliliter of culture are obtained, sufficient for use as template in fluorescence-based DNA sequencing reactions.

Bacteriophage M13↗
PubMed1996

Liver injury model in mice induced by a cellular immunologic mechanism--delayed-type hypersensitivity-induced liver injury to picryl chloride and phenotype of effector cell.

Liver injury was induced in BALB/c mice by local delayed-type hypersensitivity (DTH) to picryl chloride (PC1). Distinct changes of biochemical parameters were observed including the elevation of serum alanine and aspartate aminotransferases, increase of liver lipid peroxides, as well as decrease of serum alkaline phosphatase. Damage was confirmed by histopathological findings such as hepatocellular necrosis, granulocyte infiltration, and fatty degeneration. The liver injury was passively transferred into naive syngeneic mice by infusing spleen cells from immune mice. The capacity of the splenocytes to induce liver injury in recipient mice was almost completely abolished by pretreatment of the cells with anti-Thy 1.2 or anti-CD4, but not anti-CD8 antibody. These findings suggest that the production of liver injury by a local DTH mechanism is possible and the subpopulation of T cells, Thy-1.2+, L3T4+, and Lyt-2- cells, is at least one of the effector cells that mediate the injury.

Animals↗
PubMed1996

Induction of sensitivity to activation-induced death in primary CD4+ cells: a role for interleukin-2 in the negative regulation of responses by mature CD4+ T cells.

We examine the requirements for converting naive, mature CD4+ cells from an activation-induced death (AID)-resistant to a -sensitive phenotype. Priming for sensitivity to AID can be divided into two steps. The first is a mitogen/CD3-dependent, cyclosporin-sensitive signal and the second a cytokine-dependent, cyclosporin-insensitive one. Under these conditions, interleukin (IL)-2, but not IL-4, IL-7 or IL-15, the receptors of which share a common receptor gamma chain, is capable of providing the cytokine signal for inducing sensitivity to AID. Increased expression of the low-affinity IL-2R alpha chain (CD25) is associated with acquisition of AID sensitivity and antibodies to CD25 block acquisition of AID sensitivity in the presence of IL-2. As with T cell hybridomas, AID is dependent on both CD95 and CD95 ligand (CD95L) expression, but unlike hybridomas, the sensitive and resistant phenotypes of primary CD4+ cells cannot be distinguished by levels of CD95 expression, functional CD95L nor the fraction of cells in cycle. The results suggest that the unique function of IL-2 is to regulate proteins, either not important or constitutively regulated in T cell hybridomas, that are essential for cell-autonomous suicide of activated CD4+ cells. These experiments provide a mechanism for the recent observations of chronic lymphoproliferation and autoimmune disease in mice with null mutations in IL-2 or CD25.

Animals↗
PubMed1996

Characterization of a human cardiac gene which encodes for a LIM domain protein and is developmentally expressed in myocardial development.

A clone with high sequence homology to a rat muscle LIM protein has been isolated from a human fetal heart cDNA library. The isolated cDNA is 887 bp in length, with an open reading frame of 194 amino acid residues. Northern blot analysis revealed that it is predominantly expressed in fetal and neonatal hearts, with a low level of expression in adult heart and slow-twitch skeletal muscle (soleus). No detectable expression of this transcript was found in other tissues. Its cardiac expression and structural similarity to the rat homolog implied a regulatory role in human cardiac muscle. The biological property was confirmed by zinc binding assay, demonstrating its zinc-binding affinity. Homology of CLP to a rat muscle LIM protein and its predominantly differential expression in cardiac tissue imply its significant putative role in the development and growth of the human heart.

Adult↗
PubMed1996

Localization of a novel zinc finger gene to the human chromosome 7p11.2-p12 by fluorescence in situ hybridization.

A novel zinc finger gene (ZNF182) was isolated from a human fetal cardiac cDNA library, using a consensus C2H2 zinc finger oligonucleotide probe. This gene was assigned to human chromosome 7p11.1-p12 by fluorescence in situ hybridization (FISH). Additional FISH signals were identified on both the long and the short arms of chromosome 19, suggesting the presence of homologous genes at these loci.

Chromosome Mapping↗
PubMed1996

Localization of three novel zinc finger genes to the centromeric region of human chromosome 10 by fluorescence in situ hybridization.

An oligonucleotide probe for the consensus sequence of the linker region of zinc finger proteins was used to isolate cDNA clones from a human fetal heart cDNA library. Following DNA sequencing analysis and comparison, genes for the novel clones were mapped by fluorescence in situ hybridization. We report the chromosomal localization of three zinc finger-coding genes to the region of centromere on human chromosome 10p11.1q-11.2, indicating involvement in gene duplication and chromosome rearrangement during primate evolution.

Amino Acid Sequence↗
PubMed1996

Identification of a locus of zinc finger genes in human chromosome 19q13.1-q13.3 region by fluorescence in situ hybridization.

A group of zinc-binding cDNA clones from a human fetal heart library was isolated using an oligonucleotide probe to the consensus sequence of the linker region of zinc finger proteins. Genes for novel clones were mapped by fluorescence in situ hybridization. In the process, we identified a previously unrecognized locus for two zinc finger-coding genes in human chromosome 19q13.1-q13.3 (ZNF180,ZNF181), where genomic rearrangements were shown to be accompanied by various developmental abnormalities, DNA repair deficiencies, and cellular malignancies.

Amino Acid Sequence↗
PubMed1996

Kinetic assay of antitrypsin in human serum by a surface acoustic wave(SAW)-impedance sensor.

Antitrypsin in human serum was determined by using both the SAW-impedance sensor system and spectrophotometry, indicating that the mean value for women was significantly higher than the mean value for men; the value for acute pancreasis patients is about 2-folds of the normal values, and there is no significant difference between the acute pancreasis patients and the pancreatic cancer patients.

Journal Article↗
PubMed1996

Differential biotransformation of dynorphin A (1-17) and dynorphin A (1-13) peptides in human blood, ex vivo.

The biotransformation in human blood in vitro of three dynorphin A (Dyn A) peptides was studied by matrix assisted laser desorption mass spectrometry to determine whether the natural peptide, Dyn A(1-17), is biotransformed differently from Dyn A (1-13), the natural sequence shortened form used in numerous neurobiological and pharmacological studies. In addition to studies of Dyn A(1-17), a natural product from prodynorphin and Dyn A(1-13), a natural sequence truncation of Dyn A(1-17), Dyn A(1-10)amide, a synthetic analogue of Dyn A(1-17) presumed to be protected from rapid biotransformation was also studied Synthetic Dyn A peptides were incubated in freshly drawn blood for various periods of time prior to mass spectrometric analysis. Several peptide products were identified from each precursor; the time profiles of appearance and disappearance of the major products were followed. Substantial differences in products and especially in the rate of biotransformation were observed between the processing of Dyn A(1-17) and the two shorter Dyn A peptides, Dyn A(1-13) and Dyn A(1-10)amide. Significant amounts of the natural Dyn A(1-17) survived 4 h of incubation (half-life 3 h). Dyn A (2-17), a major processed product of Dyn A(1-17) in blood, continued to accumulate during the 4-h incubation period. By contrast, both Dyn A(1-13) and Dyn A(1-10) amide were biotransformed very rapidly with half-lives of < 1 min and 10 min, respectively. Most of the products from these two peptide precursors were also further processed rapidly, with the exception of Dyn A(4-12) and Dyn A(4-10)amide, which were detected for over 2 h. Dyn A(1-6) was found as a minor biotransformation product from all three precursor peptides. These findings suggest that an important function of the four C-terminal amino acid residues of the natural form, Dyn A(1-17) [compared to Dyn A(1-13)], is to stabilize or protect the peptide from biotransformation by enzymes, by preserving a natural hairpin structure possibly near the carboxyl-terminus.

Adult↗
PubMed1996

Depletion and bioavailability of 14C-oxibendazole residues in swine tissues.

Groups of male swine were administered a single oral dose of 14C-oxibendazole in a gelatin capsule at a level of 15 mg kg-1 bodyweight and killed after 10 h, 24 h, and 7 days withdrawal. Combustion analysis indicated that liver was the only tissue which contained significant residues. Owing to the insolubility of oxibendazole, absorption was variable, especially at the early time points. Total residues were highest after 24 h withdrawal (4 ppm) and depleted relatively slowly to approximately 1.8 ppm after 7 days. Extractable residues decreased from 35% to 11% over this same period. When 14C-oxibendazole was fortified into control, lyophilized, pelleted swine liver and fed to rats utilizing the Gallo-Torres model, bioavailability was greater than 94%. In contrast, bioavailability was substantially reduced to approximately 40% when liver containing 14C-oxibendazole residues from dosed swine was fed. This percentage remained constant for liver samples from the 24 h or 7 day withdrawal swine. The date were consistent with the rapid metabolism of oxibendazole and the early formation of a high percentage of bound tissue residues. The significant differences in residue bioavailability and extraction efficiency between the fortified control and dosed tissues indicate that little, if any, parent oxibendazole is present in the dosed tissues, even at early withdrawal times. As non-bioavailable residues are of no toxicological concern, the 60% reduction in bioavailability is significant from a regulatory perspective. The wider safety margin, relative to the established acceptable daily intake (ADI) for oxibendazole, is beneficial to the consumer in terms of human food safety.

Administration, Oral↗
PubMed1996

Expression of alpha 2-adrenergic receptor subtypes in the mouse brain: evaluation of spatial and temporal information imparted by 3 kb of 5' regulatory sequence for the alpha 2A AR-receptor gene in transgenic animals.

The present studies characterize the expression of the alpha 2A, alpha 2B and alpha 2C adrenergic receptor subtypes via in situ hybridization analysis of messenger RNA expression in the adult mouse brain, as well as the pattern of expression of alpha 2A adrenergic receptor messenger RNA at embryonic day E9.5, the earliest time for detection of the messenger RNA encoding this receptor subtype. alpha 2A adrenergic receptor messenger RNA is highly expressed in the sixth layer of the cortex and the locus coeruleus, alpha 2B adrenergic receptor messenger RNA predominantly in the thalamus and in the Purkinje layer of the cerebellum, and alpha 2C adrenergic receptor messenger RNA in the putamen caudate region of the mouse brain. Both alpha 2A and alpha 2C adrenergic receptor messenger RNA demonstrate strong expression in the amygdaloid complex, hypothalamus, olfactory system and the hippocampal formation. To develop a molecular understanding of the unique cellular expression of messenger RNA encoding the alpha 2A adrenergic receptor subtype, 2.83 kb of the upstream regulatory sequence for the alpha 2A adrenergic receptor gene was fused to the LacZ gene as a reporter gene and expression of beta-galactosidase activity was assessed in transgenic offspring. Although the spatial expression of the transgene in the adult brain often overlaps that for the endogenous alpha 2A adrenergic receptor, both ectopic expression and the absence of appropriate expression were noted; in contrast five of the six lines show temporal expression characteristic of the endogenous alpha 2A adrenergic receptor gene. The present studies provide the first characterization of messenger RNA localization for the three alpha 2 adrenergic receptor subtypes in the mouse CNS. Because the functional roles of the prazosin-sensitive alpha 2B adrenergic receptor and alpha 2C adrenergic receptor subtypes have been masked in most earlier physiological and pharmacological analyses of alpha 2 adrenergic receptor function, identifying the multiple loci alpha 2 adrenergic receptor subtype expression is an important prelude to understanding the functional roles of these three independent receptor populations in the mouse CNS. The findings in the transgenic animals indicating that approximately 3 kb of regulatory sequence has imparted faithful temporal but not spatial expression for the alpha 2A adrenergic receptor gene suggest that additional regulatory information is necessary for appropriate cell specific expression of messenger RNA for the alpha 2A adrenergic receptor subtype.

Amino Acid Sequence↗