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Biomedical subjects

D Yang

Publications and source records attributed to D Yang.

At least 181 records · Page 10Linked to original sources
PubMed1999

[New subtype of coltivirus isolated from mosquitoes in the northeast part of China].

OBJECTIVE: The purpose of this study was to isolate new arbovirus from mosquitoes collected from the northeast part of China during the summer of 1996. METHODS: The cell used for isolation were C6/36 and BHK-21 cells. RESULTS: Two strains (NE97-12 and NE97-31) of coltivirus were isolated among 68 mosquito specimens. The viruses caused cytopathogenic effects on C6/36 cell, but not on BHK-21 cells. They were resistant to both 5-IDU and ether, but sensitive to pH3.0 and temperature at 56 degrees C for 30 minutes. IFA of new isolates with mouse ascitic fluid anti-coltivirus TRT2 strain showed positive reaction. Polyacrylamide gel electrophoresis (PAGE) of two isolates showed 12 segments of double-stranded(ds) RNA and PAGE profiles were 6-5-1, which were different from that of coltivirus TRT2 strain(6-6). There was no cross neutralization between new isolates and TRT2 strain by tissue culture cross-neutralization test. CONCLUSION: The results indicated while new isolates were serologically related to TRT2 strain of coltivirus by IFA, the neutralization test suggests that it represents a distinct serotype. These new isolates isolated firstly from the northeast part of China belong to a new subtype of coltivirus.

Animals↗
PubMed1999

A common TCR V-D-J sequence in V beta 13.1 T cells recognizing an immunodominant peptide of myelin basic protein in multiple sclerosis.

T cell responses to the immunodominant peptide (residues 83-99) of myelin basic protein are potentially associated with multiple sclerosis (MS). This study was undertaken to examine whether a common sequence motif(s) exists within the TCR complementarity-determining region (CDR)-3 of T cells recognizing the MBP83-99 peptide. Twenty MBP83-99-reactive T cell clones derived from patients with MS were analyzed for CDR3 sequences, which revealed several shared motifs. Some V beta 13.1 T cell clones derived from different patients with MS were found to contain an identical CDR3 motif, V beta 13.1-LGRAGLTY. Oligonucleotides complementary to the shared CDR3 motifs were used as specific probes to detect identical target CDR3 sequences in a large panel of T cell lines reactive to MBP83-99 and unprimed PBMC. The results revealed that, in contrast to other CDR3 motifs examined, the LGRAGLTY motif was common to T cells recognizing the MBP83-99 peptide, as evident by its expression in the majority of MBP83-99-reactive T cell lines (36/44) and PBMC specimens (15/48) obtained from randomly selected MS patients. The motif was also detected in lower expression in some PBMC specimens from healthy individuals, suggesting the presence of low precursor frequency of T cells expressing this motif in healthy individuals. This study provides new evidence indicating that the identified LGRAGLTY motif is preferentially expressed in MBP83-99-reactive T cells. The findings have important implications in monitoring and targeting MBP83-99-reactive T cells in MS.

Amino Acid Sequence↗
PubMed1999

Cutting edge: immature dendritic cells generated from monocytes in the presence of TGF-beta 1 express functional C-C chemokine receptor 6.

Although CD34+ progenitor-derived immature dendritic cells (DCs) express CCR6, several recent studies reported that monocyte-derived immature DCs do not do so. We observed that DCs generated from monocytes in the presence of GM-CSF, IL-4, and TGF-beta 1 consistently responded to liver and activation-regulated chemokine (LARC, also known as macrophage inflammatory protein-3 alpha). These immature DCs expressed one class of high-affinity binding sites for LARC, and expressed both CCR6 mRNA and protein. Therefore, LARC-CCR6 interaction presumably also contributes to the regulation of trafficking of monocyte-derived DCs, and utilization of TGF-beta can potentially provide a ready source of CCR6+ monocyte-derived DCs for therapeutic purposes.

Binding Sites↗
PubMed1999

Identification of a gene coding for a protein possessing shared tumor epitopes capable of inducing HLA-A24-restricted cytotoxic T lymphocytes in cancer patients.

Genes encoding tumor epitopes that are capable of inducing CTLs against adenocarcinomas and squamous cell carcinomas, two major human cancers histologically observed in various organs, have rarely been identified. Here, we report a new gene from cDNA of esophageal cancer cells that encodes a shared tumor antigen recognized by HLA-A2402-restricted and tumor-specific CTLs. The sequence of this gene is almost identical to that of the KIAA0156 gene, which has been registered in GenBank with an unknown function. This gene encodes a Mr 140,000 protein that is expressed in the nucleus of all of the malignant tumor cell lines tested and the majority of cancer tissues with various histologies, including squamous cell carcinomas, adenocarcinomas, melanomas, and leukemia cells. However, this protein was undetectable in the nucleus of any cell lines of nonmalignant cells or normal tissues, except for the testis. Furthermore, this protein was expressed in the cytosol of all of the proliferating cells, including normal cells and malignant cells, but not in normal tissues, except for the testis and fetal liver. Two peptides of this protein were recognized by HLA-A2402-restricted CTLs and were able to induce HLA-A24-restricted and tumor-specific CTLs from peripheral blood mononuclear cells of most of HLA-A24+ cancer patients tested, but not from peripheral blood mononuclear cells of any healthy donors. These peptides may be useful in specific immunotherapy for HLA-A24+ cancer patients with various histological types.

Antigens, Neoplasm↗
PubMed1999

T cell responses to myelin basic protein in patients with spinal cord injury and multiple sclerosis.

Autoimmune inflammation secondary to myelin destruction may play an inhibitory role in restoration of nerve functions in spinal cord injury (SCI). In this study, we demonstrated that T cells recognizing myelin basic protein (MBP) occurred at a high precursor frequency in patients with SCI, which was compatible to that in patients with multiple sclerosis (MS), a disease of presumed autoimmune pathology. The findings suggest of hyperactivity of MBP-reactive T cells in patients with SCI. MBP-reactive T cell lines derived from patients with SCI exhibited a preferential recognition pattern toward the 81-99 and the 151-169 regions of MBP. There were functional differences in the epitope recognition and cytokine profile between two panels of MBP-reactive T cell lines derived from patients with SCI and patients with MS. The study provides new evidence important for further investigation of the role of the inflammatory component in SCI.

Adult↗
PubMed1999

Cluster formation by protein kinase Ctheta during murine T cell activation: effect of age.

Protein kinase Ctheta; (PKCtheta;) is thought to play an important role in T cell activation, in that exposure of cloned T cells to antigen-presenting cells bearing agonist peptides, but not antagonist peptides, leads to clustering of PKCtheta; molecules in the section of the T cell plasma membrane that is in contact with the APCs. To see whether aging affects this PKCtheta; clustering reaction in mouse T lymphocytes, we used immunofluorescence staining and confocal microscopy to observe the localization of PKCtheta; in CD4 and CD8 T lymphocytes activated by coincubation with anti-CD3 hybridoma cells. Aging led to a twofold decline in the proportion of both CD4 and CD8 T cells in which PKCtheta; underwent cluster formation. This decrease with age was not due to differences in the number of cell conjugates formed, nor to kinetic differences of PKCtheta; clustering, nor to the accumulation of memory T cells in old mice. There were no effects of aging on the levels or kinase activity of PKCtheta; in murine T cells. Our data suggest alterations in the upstream signals that regulate PKCtheta; translocation.

Aging↗
PubMed1999

Mutational analysis of sites in the translational regulator, PHAS-I, that are selectively phosphorylated by mTOR.

Results obtained with PHAS-I proteins having Ser to Ala mutations in the five known phosphorylation sites indicate that mTOR preferentially phosphorylates Thr36 and Thr45. The effects of phosphorylating these sites on eIF4E binding were assessed in a far-Western analysis with a labeled eIF4E probe. Phosphorylation of Thr36 only slightly attenuated binding of PHAS-I to eIF4E, while phosphorylation of Thr45 markedly inhibited binding. Phosphorylation of neither site affected the electrophoretic mobility of the protein, indicating that results of studies that rely solely on a gel-shift assay to assess changes in PHAS-I phosphorylation must be interpreted with caution.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed1999

Wild-type but not Alzheimer-mutant amyloid precursor protein confers resistance against p53-mediated apoptosis.

Amyloid precursor proteins (APPs) are expressed in multiple organs and cell types in diverse species. Their conservation across species and high abundance in brain and the association of various APP missense mutations with autosomal dominant forms of familial Alzheimer's disease (FAD) suggest important roles for APP in the central nervous system. However, the basic functions of APP in the central nervous system remain largely unknown. To assess potential effects of APP on neuronal death and survival, we transfected APP-deficient rat neuroblastoma cells (B103) with DNA constructs encoding wild-type or FAD-mutant human APP. Wild-type, but not FAD-mutant, APP effectively protected cells against apoptosis induced by ultraviolet irradiation, staurosporine, or p53. Wild-type APP also strongly inhibited p53 DNA-binding activity and p53-mediated gene transactivation, whereas FAD-mutant APP did not. We conclude that APP protects neuronal cells against apoptosis by controlling p53 activation at the post-translational level. Disruption of this function by mutations or alterations in APP processing could enhance neuronal vulnerability to secondary insults and contribute to neuronal degeneration.

Alzheimer Disease↗
PubMed1999

Antiproliferative effect of IL-1 is mediated by p38 mitogen-activated protein kinase in human melanoma cell A375.

The role of p38 mitogen-activated protein kinase (MAPK) in IL-1-induced growth inhibition was investigated using IL-1-sensitive human melanoma A375-C2-1 cells and IL-1-resistant A375-R8 cells. In both cells, p38 MAPK was activated by IL-1. A selective inhibitor for p38 MAPK, SB203580, almost completely recovered the IL-1-induced growth inhibition in A375-C2-1 cells. IL-1-induced IL-6 production was also suppressed by SB203580. However, the reversal effect of SB203580 was not due to the suppression of IL-6 production because the SB203580 effect was still observed in the presence of exogenous IL-6. Down-regulation of ornithine decarboxylase (ODC) activity as well as its protein level has been shown to be essential for IL-1-induced growth inhibition. SB203580 also reversed the IL-1-induced down-regulation of ODC activity and intracellular polyamine levels without affecting ODC mRNA levels in A375-C2-1 cells. In IL-1-resistant R8 cells, however, IL-1 only slightly suppressed ODC activity. In A375-C2-1 cells, the mRNA expression level of antizyme (AZ), a regulatory factor of ODC activity, has been shown to be up-regulated by IL-1. IL-1-induced up-regulation of AZ mRNA level was not affected by SB203580. These findings demonstrate that p38 MAPK plays an important role in IL-1-induced growth inhibition in A375 cells through down-regulating ODC activity without affecting the level of ODC mRNA and AZ mRNA. In IL-1-resistant A375-R8 cells, IL-1 signaling pathway is deficient between p38 MAPK activation and down-regulation of ODC activity.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed1999

Vicia root micronucleus assay on the clastogenicity of water samples from the Xiaoqing River in Shandong Province of the People's Republic of China.

Vicia root micronucleus assay was used to determine the clastogenicity of water samples from Xiaoqing River that passes through Jinan City. Positive results were obtained from eight water collecting sites. This indicates that the water in most areas of this river was polluted with industrial waste and municipal sewage. Results of this study proves that biomonitoring with Vicia root micronucleus test is an efficient way to assess the water quality of this river.

Biological Assay↗
PubMed1999

Viral myocarditis: identification of five differentially expressed genes in coxsackievirus B3-infected mouse heart.

Differences in host susceptibility to viral myocarditis caused by a given strain of coxsackievirus B3 (CVB3) are known to be largely related to host genetic factors. Little is known, however, about the key genes that encode determinants (mediators) of myocarditis development or the nature of injury. To identify these genes and further understand the molecular mechanisms of the disease process, we have used a murine model and the differential display technique to fingerprint mRNAs from CVB3-infected mouse hearts. Total RNA was extracted from hearts of 4- and 10-week-old A/J(H-2(a)) mice at day 4 after CVB3 infection, and mRNAs were detected by reverse transcriptase-polymerase chain reaction and subsequently analyzed on polyacrylamide DNA sequencing gels. The differentially displayed bands were confirmed by Northern hybridization using the bands as cDNA probes. Twenty-eight upregulated or downregulated bands were selected from the sequencing gels; among these, 2 upregulated and 3 downregulated cDNA fragments were confirmed by Northern hybridization. DNA sequence analysis and GenBank searching have determined that 4 of the 5 candidate genes are homologous to genes encoding Mus musculus inducible GTPase, mouse mitochondrial hydrophobic peptide (a subunit of NADH dehydrogenase), mouse beta-globin, and Homo sapiens cAMP-regulated response element binding protein (CREB) binding protein (CBP), respectively. The remaining candidate gene matches an unpublished cDNA clone, M musculus Nip21 mRNA (GenBank accession number, AF035207), which is homologous to human Nip2, a Bcl-2 binding protein. Our data suggest preliminarily that both structural and nonstructural genes are involved in myocarditis development. For the structural gene, beta-globin, we further confirmed its downregulation at the protein level by measuring the mean cell volume of red blood cells and found it was marginally reduced in the CVB3-infected group (P<0.06), with no change in hemoglobin concentration. Cardiac myoglobin concentration was also measured and found to be decreased (P<0.005), with a parallel decrease in total soluble protein in the CVB3-infected mouse myocardium (P<0.01). We also noted that the ratio of myoglobin to total protein was not significantly changed; this may be due to the downregulation of additional genes in the host heart, a number being observed on the differential display gels. The significant downregulation of beta-globin major gene expression in the heart may be relevant to impaired cardiac function in both the early and late postinfection period. The other identified nonstructural genes are known to be involved in regulation of gene expression, signal transduction pathways, and apoptotic cell death. The altered expression of structural and nonstructural genes may play important roles in the mediation of myocarditis development and perhaps other pathological processes in the heart.

Animals↗
PubMed1999

[Effect of dimethoate on the expression of c-fos gene in skeletal muscle].

To elucidate the effect of organophosphate pesticides on the expression of immediate early gene in skeletal muscle, the concentrations of c-fos mRNA and protein were measured by RT-PCR and western dot blot techniques. The result showed that c-fos mRNA and protein were significantly increased in skeletal muscle of rat after dosing with dimethoate. These results indicated that c-fos might act as transcription factor and regulate other gene expression during the early period of organophosphate intoxication.

Animals↗
PubMed1999

Monocarboxylic-based phosphotyrosyl mimetics in the design of GRB2 SH2 domain inhibitors.

Three monocarboxylic-containing analogues, O-carboxymethyltyrosine (cmT, 5), 4-(carboxymethyl)phenylalanine (cmF, 6), and 4-(carboxydifluoromethyl)phenylalanine (F2cmF, 7) were utilized as phosphotyrosyl (pTyr) replacements in a high affinity B-bend mimicking platform, where they exhibited IC50 values of 2.5 microM, 65 microM and 28 microM, respectively, in a Grb2 SH2 domain Biacore binding assay. When a terminal N(alpha)-oxalyl axillary was utilized to enhance ligand interactions with a critical SH2 domain Arg67 residue (alphaA-helix), binding potencies increased from 4- to 10-fold, resulting in submicromolar affinity for cmF (IC50 = 0.6 microM) and low micromolar affinity for F2cmF (IC50 = 2 microM). Cell lysate binding studies also showed inhibition of cognate Grb2 binding to the p185erbB-2 phosphoprotein in the same rank order of potency as observed in the Biacore assay. These results indicate the potential value of cmF and F2cmF residues as pTyr mimetics for the study of Grb2 SH2 domains and suggest new strategies for improvements in inhibitor design.

Adaptor Proteins, Signal Transducing↗
PubMed1999

15N enrichment of ammonium, glutamine-amide and urea, measured via mass isotopomer analysis of hexamethylenetetramine.

Ammonium is an important intermediate of protein metabolism and is a key component of acid-base balance. Investigations of the metabolism of NH(4)(+) in vivo using isotopic techniques are difficult because of the low concentration of NH(4)(+) in biological fluids and because of frequent artifactual isotopic dilution of the enrichment of NH(4)(+) during the assay. A new gas chromatographic mass spectrometric method was designed to monitor the (15)N enrichment and concentration of NH(4)(+) in vivo. These are both calculated from the mass isotopomer distribution of hexamethylenetetramine (HMT) formed by reacting NH(4)(+) with formaldehyde. The enrichment of NH(4)(+) is amplified four times since the HMT molecule contains four atoms of nitrogen derived from NH(4)(+). This allows the measurement of low (15)N enrichment of NH(4)(+), down to 0.1%. (15)N enrichment of urea and of the amide N of L-glutamine are measured by enzymatic release of NH(4)(+) and conversion of the latter to HMT. These new techniques facilitate in vivo investigations of the metabolism of NH(4)(+) and related compounds.

Amides↗
PubMed1999

An extended dorsal island skin flap with multiple vascular territories in the rat: A new skin flap model.

BACKGROUND: The use of various animal skin flap models can lead to difficulty in the interpretation of experimental findings. Establishment of an axial-pattern flap model with predictable necrosis is desirable for the study of the flap pathophysiology. MATERIALS AND METHODS: Twenty rats were injected with a lead oxide, gelatin, and water mixture through the carotid artery to investigate the cutaneous vascular anatomy. Each cutaneous perforator on the rat dorsum was dissected to its source artery. The skin was removed and radiographed to define its vascular architecture. On the basis of the initial angiographic data, an extended dorsal island skin flap (based on the unilateral deep circumflex iliac artery) measuring up to 8 x 9 cm was designed in 10 rats to assess the viability of the flap. The boundaries of the flap are defined by anatomical landmarks to standardize the flap for rats of different sizes. The upper margin was located at the level of the tip of the scapula and the lower margin at a level 2 cm below the iliac crest. All flaps were observed for 7 days postoperatively and the surviving flap area was calculated as a percentage of total flap dimensions using the paper template technique. RESULTS: Most of the skin of the rat dorsum is supplied by three arteries: the deep circumflex iliac artery (DCIA), the posterior intercostal arteries (PIA), and the lateral thoracic artery (LTA). The DCIA anastomoses with the ipsilateral PIA and the contralateral PIA and DCIA. The average percentage survival of the skin flap is 70.5 +/- 4.8% (mean +/- SD). CONCLUSIONS: The extended dorsal island skin flap has a consistent vasculature and has a predictable distal necrosis area. This new model is felt to be appropriate for skin flap physiological studies.

Animals↗
PubMed1999

The structure and evolution of the ribosomal proteins encoded in the spc operon of the archaeon (Crenarchaeota) Sulfolobus acidocaldarius.

The genes for nine ribosomal proteins, L24, L5, S14, S8, L6, L18, S5, L30, and L15, have been isolated and sequenced from the spc operon in the archaeon (Crenarchaeota) Sulfolobus acidocaldarius, and the putative amino acid sequence of the proteins coded by these genes has been determined. In addition, three other genes in the spc operon, coding for ribosomal proteins S4E, L32E, and L19E (equivalent to rat ribosomal proteins S4, L32, and L19), were sequenced and the structure of the putative proteins was determined. The order of the ribosomal protein genes in the spc operon of the Crenarchaeota kingdom of Archaea is identical to that present in the Euryarchaeota kingdom of Archaea and also identical to that found in bacteria, except for the genes for r-proteins S4E, L32E, and L19E, which are absent in bacteria. Although AUG is the initiation codon in most of the spc genes, GUG (val) and UUG (leu) are also used as initiation codons in S. acidocaldarius. Over 70% of the codons in the Sulfolobus spc operon have A or U in the third position, reflecting the low GC content of Sulfolobus DNA. Phylogenetic analysis indicated that the archaeal r-proteins are a sister group of their eucaryotic counterparts but did not resolve the question of whether the Archaea is monophyletic, as suggested by the L6P, L15P, and L18P trees, or the question of whether the Crenarchaeota is separate from the Euryarchaeota and closer to the Eucarya, as suggested by the S8P, S5P, and L24P trees. In the case of the three Sulfolobus r-proteins that do not have a counterpart in the bacterial ribosome (S4E, L32E, and L19E), the archaeal r-proteins showed substantial identity to their eucaryotic equivalents, but in all cases the archaeal proteins formed a separate group from the eucaryotic proteins.

Amino Acid Sequence↗
PubMed1999

Angiopoietin-1 and its receptor Tie-2 participate in the regulation of capillary-like tubule formation and survival of endothelial cells.

Angiopoietin-1 (Ang-1) and its receptor Tie-2, a trans-membrane tyrosine kinase uniquely expressed by endothelial cells, are shown by null mutation studies to be essential to developmental angiogenesis. The phenotypic abnormalities in these knockout animals suggest that Tie-2 signaling is necessary for the maintenance and expansion of the primitive capillary network. We present in vitro evidence indicating that the Ang-1/Tie-2 system participates in the regulation of capillary tubule formation and is necessary for the survival of confluent endothelial cells. Although recombinant Ang-1, which induces Tie-2 phosphorylation, has no effect on the proliferation of endothelial cells, treatment of confluent adult bovine aortic endothelial cells (ABAE) cells grown on collagen gels with Ang-1 (100 ng/ml) causes the cells to migrate into the collagen gel and form capillary-like tubules. The tubule-forming effect of Ang-1 is similar to the effect caused by FGF-2. A soluble form of the Tie-2 extracellular domain, in fivefold molar excess, blocks Ang-1-induced tubule formation. Specific elimination of Tie-2 protein expression in cultured ABAE cells as a result of transfection with an antisense oligonucleotide causes cell death in a dose-dependent manner (IC(50) = 50 nM). The antisense treatment has no effect on cells that do not express Tie-2. Cells treated with antisense oligonucleotide show a sixfold increase in the rate of apoptosis as assessed by in situ end labeling of fragmented DNA. These findings are consistent with the view that Ang-1/Tie-2 signaling is essential for both angiogenesis and endothelial cell survival.

3T3 Cells↗