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Biomedical subjects

K Wang

Publications and source records attributed to K Wang.

At least 325 records · Page 18Linked to original sources
PubMed1997

A highly conserved apoptotic suppressor gene is located near the chicken T-cell receptor alpha chain constant region.

A cosmid clone containing the chicken T-cell receptor alpha chain constant region (TCRAC) was sequenced. The cosmid contains the TCRAC gene, six putative joining gene segments (TCRAJ), and surprisingly, a chicken homologue for the human apoptotic suppressor gene, defender against cell death (DAD1). The DAD1 gene is 6.3 kilobases downstream of the TCRAC gene and has an inverted transcription orientation with respect to the TCRAC gene. The cDNA for the chicken DAD1 gene is 597 base pairs in length and encodes a highly conserved hydrophobic protein. The proximal location of DAD1 to the TCRAC locus has also been confirmed in both humans and mouse. The location of the DAD1 gene suggests that DAD1 may play an important role in T-cell related apoptotic activities.

Amino Acid Sequence↗
PubMed1997

Histocompatibility gene mutation rates in the mouse: a 25-year review.

Mutation rates of H2 and non-H2 histocompatibility genes in the mouse are examined over a 25-year period. Detected by skin graft rejections, the mutations were screened in inbred and hybrid mice from a continuously maintained and monitored colony and from a regularly supplied set of mice provided from the National Cancer Institute for monitoring of genetic integrity. Twenty-five H2 mutations were recovered, involving the K, D, L, and Ab loci, as well as over 80 mutations of non-H2 histocompatibility genes. Aside from a single allele at a single locus (H2-Kb), the spontaneous mutation rate of H2 class I genes appears to be equivalent to that found estimated for non-H2 histocompatibility genes, and comparable to rates reported for a variety of mouse genes. This is in contrast with previous suggestions that H2 genes mutate at orders of magnitude greater than do "average" mammalian genes. The discrepancy is attributed to the H2-Kb gene which accounts for over half of all reported H2 mutations and which mutates spontaneously at a rate of 1-2 x 10(-4) per gene per generation. Furthermore, over half of the spontaneous H2-Kb mutations result in a single mutant phenotype (the "bg" group) which involve similar changes at amino acid residues 116 and 121. Thus, the high spontaneous mutation rate for H2-Kb appears to be the exception among major histocompatibility genes, rather than the rule.

Animals↗
PubMed1997

FT-Raman studies on the transformation of G-actin to F-actin, the binding of cisplatin and transplatin to F-actin and the effects of the conformation of F-actin.

The conformation change of G-actin of F-actin and the binding modes of cisplatin and transplatin to F-actin have been studied by FT-Raman spectroscopy. The studies show that the process of polymerization is related to the vibration of C-S Gauche mode (approximately 650 cm-1), which indicates that the methionine (Met) contributes to the polymerization of actin. The relative intensity of I(925)/I(803), reflecting the conformation of actin secondary structure, does not change during the polymerization process. The effect of cisplatin and transplatin on F-actin is dependent on the species and their concentrations. Cisplatin, at high concentrations, affects the conformation of F-actin mainly by binding with the sulphur of methionine. Transplatin, even at low concentrations, obviously affects the F-actin's conformation due to it's multiple binding sites, on N-containing sites in addition to S-methionine sites. These results relate to the differences in pharmacology and toxicology effects of the complexes.

Actins↗
PubMed1997

TCRV and TCRJ gene usage in MBP responding T cells from (B10.PL x PL/J)F1 mice is biased towards that of B10.PL mice.

We analyzed myelin basic protein (MBP) specific T cell hybridoma clones from (B10.PL x PL/J)F1 mice. MBP-reacting T cell hybridomas from F1 mice preferentially expressed B10.PL TcraV2.3 (53%) and B10.PL TcraV4.2 (13%) with minor expression of TcraV4.4 (13%) gene segments. A dominant expression of TcrbV8.2 (73%) accompanying with TcrbV8.1 (20%) and TcrbV13 (7%) gene segments have been identified in these MBP-reacting T cell hybridomas from F1 mice. There was less restrictive but non-random usage of the TcraJ and TcrbJ gene segments. Overall, the MBP-reacting T cell hybridomas from (B10.PL x PL/J)F1 mice were dominated by the MBP-reacting T cell pattern seen in B10.PL mice.

Amino Acid Sequence↗
PubMed1997

Molecular identification and relatedness of potato witches'-broom phytoplasma isolates from four potato cultivars.

Four isolates of potato witches'-broom phytoplasma, designated as PW1, PW2, PW3 and PW4, were established on four potato cultivars. The identity of each isolate was confirmed by PCR using two universal primer pairs and one specific primer set derived from phytoplasma of 16S rDNA sequences. The four isolate samples formed similar RFLP patterns after digestion of 1.2 kb PCR products with restriction endonucleases AluI, HhaI, RsaI and Sau3A. The direct DNA sequencing with the specific primer pair showed that there are no differences in the base sequences among PW1, PW2, and PW3 phytoplasma isolates and that PW4 is closely related to them. Thus, the four isolates were identified as members of the clover proliferation group.

Base Sequence↗
PubMed1997

The chirality selectivity in the uptake of platinum (II) complexes with 1,2-cyclohexanediamine isomers as carrier ligand by human erythrocytes.

The uptake kinetics of cisplatin analogs of 1,2-cyclohexanediamine(dach) isomers with various leaving groups, by human erythrocytes in plasma isotonic buffer, were studied. The experimental results showed that the uptake rate constants (k values) decrease with the change of leaving group in the sequence: chloride (Cl) > squaric acid (SA) > oxalate (OX) > demethylcantharic acid (DA), with the same dach isomer as carrier group. It is noteworthy that for the platinum (II) complexes with the same leaving group, the k values always reduce as: 1R, 2R-dach > 1R, 2S-dach > 1S, 2S-dach. This result reflects the chirality selectivity. No differences in reactivity to protein thiols and effects on membrane permeability were found for the R,R-, R,S-, S,S-isomeric complexes. It is proposed that the chirality selectivity in uptake is due to the recognition of the chirality of the platinum complexes by the erythrocyte membrane. The interactions between the chiral platinum complexes and the head groups of the membrane phospholipid molecules are probably involved.

Cell Membrane Permeability↗
PubMed1997

Binding of vanadate to human erythrocyte ghosts and subsequent events.

Spectroscopic techniques were used to investigate the interaction between vanadate and human erythrocyte ghosts. Direct evidence from 51 V nuclear magnetic resonance (NMR) studies suggested that the monomeric and polymeric vanadate species may bind to the anion binding sites of band 3 protein of the erythrocyte membrane. The results of 51V NMR studies and the quenching effect of vanadate on the intrinsic fluorescence of the membrane proteins indicated that in the low concentration range of vanadate (< 0.6 mM), monomeric vanadate binds mostly to the anion sites of band 3 protein with the dissociation constant close to 0.23 mM. The experiments of sulfhydryl content titration by the method of Ellman and residue sulfhydryl-labeled fluorescence spectroscopies clearly displayed that vanadate reacts directly with sulfhydryl groups. The appearance of the anisotropic election spin resonance (ESR) signal of vanadyl suggests that a small (c.3%) amount of vanadate was reduced by sulfhydryl groups of membrane proteins. The fluidity and order of intact ghost membrane were reduced by the reaction with vanadate, as shown by the ESR studies employing the protein- and lipid-specific spin labels. It was concluded that although vanadates mainly bind to band 3 protein, a minor part of vanadate may oxidize the residue sulfhydryl groups of membrane proteins, and thus decrease the fluidity of erythrocyte membrane.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1997

Biochemical and molecular characterization of the insecticidal fragment of CryV.

Two C-terminal deletion constructs were made to study the effect of such deletions on the biological activity of the CryV protein of Bacillus thuringiensis subsp. kurstaki. The results of feeding on neonatal larvae of Ostrinia nubilalis (European corn borer [ECB]) indicated that the 50% lethal dose of the full-length CryV protein was 3.34 micrograms/g of diet (95% fiducial limits, 2.53 to 4.32 micrograms/g of diet). Removal of 71 amino acids (aa) from the C terminus had little effect on toxicity, whereas deletion of 184 aa abolished the insecticidal activity of the CryV protein completely. Truncations of the full-length CryV protein were also generated with trypsin and the midgut protease of ECB. The proteolytically treated products were characterized by determining their N-terminal amino acid sequences. The CryV protein was found to be cleaved by both proteases through a two-step process. Initially an intermediary form was generated which contained aa 45 of full-length CryV as its N-terminal end. The C-terminal end of this peptide was not experimentally determined. However, analysis of the deduced amino acid sequence of CryV indicated that the C-terminal end of the intermediary form is likely either aa 655 or 659. Further N-terminal processing of the intermediary form resulted in a protease-resistant core form. The core included aa 156 to aa 655 or 659. While the intermediary form retained 100% of the ECB larval toxicity, the core form exhibited only approximately 22% of the toxicity of the full-length protein.

Animals↗
PubMed1997

A novel Arthrobacter beta-galactosidase with homology to eucaryotic beta-galactosidases.

An Arthrobacter beta-galactosidase has homology with the lysosomal acid beta-galactosidases from humans and mice and with a Xanthomonas manihotis enzyme. Phylogenetic analysis of the deduced amino acid sequence showed an unusual pattern, with this procaryotic enzyme clustering within the animal clade. The gene encodes a subunit of 52 kDa, and the enzyme appears to be active as a dimer. The enzyme hydrolyzed substrates with either a beta-1,4 or a beta-1,3 linkage.

Amino Acid Sequence↗
PubMed1997

Mutations in the 5' end of the herpes simplex virus type 2 latency-associated transcript (LAT) promoter affect LAT expression in vivo but not the rate of spontaneous reactivation of genital herpes.

The primary herpes simplex virus type 2 (HSV-2) latency-associated transcript (LAT) promoter influences LAT expression and rates of virus reactivation. We explored the biological importance of particular neuronally responsive regions within the promoter by creating new recombinant viruses bearing a targeted deletion (246 bp [strain 524]) or a point mutation (2 bp [strain 167]) in this region. These recombinant viruses grew efficiently in vitro and in vivo, caused acute genital disease in guinea pigs, and, as measured by quantitative-competitive (QC) DNA PCR, established latency, all as well as did the wild-type parental HSV-2 strain 333, the rescuant strain 524R, and the previously described 624-bp LAT- promoter deletion mutant. By QC-reverse transcriptase PCR of RNA from latently infected ganglia, mutant 167 expressed wild-type levels of LAT and the deletion mutant 524 expressed 9- to 15-fold less LAT than normal, while the LAT expression of the LAT- mutant was undetectable or at least 5 log units less than that of the wild type. The rates of recurrence of genital lesions were normal for recombinant viruses 524 and 167 but reduced (as expected) for the LAT- mutant. Alteration of a subset of LAT promoter elements reduced LAT expression by 1 log unit but did not influence the rate of spontaneous disease reactivation in vivo. Far greater reductions in LAT expression are necessary before reactivation rates are noticeably changed.

Animals↗
PubMed1997

TeleInViVo: a collaborative volume visualization application.

Converging technologies in the areas of networks, volume visualization algorithms, and computer performance have made possible the development of a new tool for collaboration, which extends the reach of health professionals, and other consumers of volumetric data around the world. TeleInViVo(tm) is a three-dimensional (3D) collaborative volume visualization tool for medical applications. It extends the capabilities of InViVo(tm), a fast volume visualization tool developed at the Fraunhofer IGD, Darmstadt, Germany [1-3], with efficient and intuitive network collaboration features for remote consultation and new modes of interaction. The software runs on both UNIX and Windows NT platforms. TeleInViVo provides a high degree of interactivity for the medical professional when interacting with the patient data, facilitates explanation and communication between field personnel and medical experts located far from the field, and permits viewing of the data in a multitude of ways designed to support rapid and accurate diagnosis. Current efforts involve architectural enhancements to support multiuser, distributed telemedical scenarios. The application includes the following features: Volume and subvolume data transmission at user specified resolution, Synchronization cues, Integration of Immersion Probe(tm), a 6 degree-of-freedom input device, for ergonomic 3D data exploration, Tools for measuring distances, Tools for planning instrument path, Arbitrary cutting planes in real time, Interactive segmentation tools, Virtual video recorder and playback (cine loops), 3D stereo mode. TeleInViVo is an essential part of the MUSTPAC-1 portable 3D ultrasound system developed by Battelle Pacific Northwest Labs, Richland, WA.

Computer Communication Networks↗
PubMed1997

[Investigation on the resources of medicinal centipedes and identification on their commodities].

Through investigation on the resources of medicinal centipedes and identification on corresponding medicinal materials, the original animals of medicinal centipedes are Scolopendra mutilans, S. multidens, S. mojiangica and S. negrocaptis. The main commercial medicinal centipede is S. mutilans. Its yield accounts for 95%. This paper arranged the retrieve tables of the morphological characters of original animals and commercial materials of medicinal centipedes.

Animals↗