Biomedical subjects

W Ding

Publications and source records attributed to W Ding.

At least 55 records · Page 3Linked to original sources

PubMed2000

High efficiency and wideband gyro-traveling-wave-tube amplifier

A model is presented for a wideband gyro-traveling-wave-tube amplifier. The model's output bandwidth is comparable to that of the existing wideband model, but its efficiency is improved a lot. In this model, after choosing a proper initial magnitude, the axial magnetic field has a slightly linear decrease from a given position in the interaction section. The interaction mechanism of the beam wave is analyzed and verified by numerical simulation. When the beam current is 7 A, voltage is 90 KV, the velocity ratio is 1.0, and the axial velocity spread is 2%, numerical results show a constant bandwidth of 20% with an efficiency of 42%; the peak power and gain are, respectively, 260 KW and 47 dB.

Journal Article↗

PubMed2000

Human T-lymphotropic virus type 1 p30(II) functions as a transcription factor and differentially modulates CREB-responsive promoters.

Human T-lymphotropic virus type 1 (HTLV-1), a complex retrovirus, causes adult T-cell lymphoma/leukemia and is linked to a variety of immune-mediated disorders. The roles of proteins encoded in the pX open reading frame (ORF) II gene region in HTLV-1 replication or in mediating virus-associated diseases remain to be defined. A nucleus-localizing 30-kDa protein, p30(II), encoded within pX ORF II has limited homology with the POU family of transcription factors. Recently, we reported that selected mutations in pX ORF II diminish the ability of HTLV-1 to maintain high viral loads in infected rabbits. Herein we have tested the transcriptional ability of p30(II) in mammalian cells by using yeast Gal4 fusion protein vectors and transfection of luciferase reporter genes driven by CREB-responsive promoters. p30(II) as a Gal4 DNA-binding domain (DBD) fusion protein transactivates Gal4-driven luciferase reporter gene activity up to 25-fold in 293 and HeLa-tat cells. We confirmed nuclear localization of p30(II) and demonstrate dose-dependent binding of p30(II)-Gal4(DBD) to Gal4 DNA-binding sites. The transcriptional activity of p30(II)-Gal4(DBD) was independent of TATA box flanking sequences, as shown by using two different Gal4 reporter systems. Studies of selected p30(II) mutants indicated that domains that mediate transcription are restricted to a central core region of the protein between amino acids 62 and 220. Transfection of a p30(II)-expressing plasmid repressed cellular CRE-driven reporter gene activity, with or without Tax expression. In contrast, p30(II) at lower concentrations enhanced HTLV-1 long terminal repeat-driven reporter gene activity independent of Tax expression. These data are the first to demonstrate a transcriptional function for p30(II) and suggest a mechanism by which this nuclear protein may influence HTLV-1 replication or cellular gene expression in vivo.

Animals↗

PubMed2000

[Information behavior of microsatellite loci in genome scanning].

OBJECTIVE: To determine the heterozygosity and polymorphism information content of 139 microsatellite loci in Han population. METHODS: Multiplex approach was used to analyze the 139 loci. The amplified fragments were subjected to electrophoresis in PAGE gel and analyzed with Genescan( TM) and Genotyper(TM). RESULTS: The heterozygosities are between 0.35 to 0.89, with the heterozygosities of 88% loci >0.60. PICs are in the range of 0.32 and 0.88, with PICs of 95% loci >0.50. CONCLUSION: The polymorphism information content of microsatellite loci is very high and their distribution varies in different races and populations.

Aged↗

PubMed2000

[The design of axial flow pump].

Axial flow pump has been the hot point of the research field of circulatory support. This article has outlined the basic principle of its design and the methodology of its experimental study, and explained that excellent engineer design, avoiding turbulence, cavitation and wake, and reducing the destroy of red blood cells were the goal to get in design process. The computer-supported design and virtual experiment offered the high efficient tool for the above design. The axial pump has a broad scope in future clinical application.

Computer-Aided Design↗

PubMed2000

[Expression of proliferation and apoptosis related genes in colorectal adenoma with malignant transformation].

OBJECTIVE: The effect of proliferation and apoptosis related genes of colorectal adenoma with malignant transformation and its clinicopathologic significance was studied. METHODS: p53, bcl-2, Fas, bax expression were detected immunohistochemically in 61 cases of colorectal adenoma with either mild or severe dysplasia and carcinoma. The rate of proliferation was evaluated with Ki-67 and apoptosis with TUNEL. RESULTS: The positive rates for p53 and bcl-2 protein in carcinomatous area, adenoma with severe and mild dysplasia were 67.2%, 57.4%, 19.7% and 77.1%, 80.3%, 49.2% respectively. The mean Ki-67 index and PCD index were 38.4%, 36.5%, 16.1% and 2.2%, 1.9%, 0.5% respectively. The difference of the expression of p53 protein, bcl-2 protein and Ki-67 index, PCD index in carcinomatous region and adenoma with severe dysplasia compared with mild dysplasia was statistically significant (P < 0.05). CONCLUSION: It is apparent that both apoptosis inhibition and abnormal proliferation play an important role in tumor formation. Adenoma with severe dysplasia is a lesion very close to carcinoma in nature, which possesses active tendency to become fully malignant. Detection of these proteins is important in the early diagnosis of malignant transformation of an adenoma.

Adenoma↗

PubMed2000

[Study on the relationship between microvascular density and prognosis in laryngeal cancer].

OBJECTIVE: To study the relationship between the microvascular density(MVD) and the prognosis in laryngeal cancer. METHOD: Microvessel quantitation in 31 cases of laryngeal cancer was done with factor VIII-related antibody and SABC method. RESULT: The quantitation of microvessels in laryngeal cancer were negative of histologic grade and type, but were significantly different (P < 0.05) between metastasis (10.23 +/- 0.78) and without metastasis(6.38 +/- 0.33) two years after operation. CONCLUSION: The angiogenesis of laryngeal cancer is correlated with the lymph node metastasis and prognosis.

Adult↗

PubMed2000

[An observation on long-term influence of middle ear bacterial infection on inner ear function and systemic immune reaction].

OBJECTIVE: To understand whether long-term inner ear heat shock response related to heat shock protein(HSP70) caused by middle ear bacterial infection and the potential influence on inner ear function. METHODS: Sixty BALB/c mice were randomly classified into 6 groups including Klebsiella pneumoniae (KP), Staphylococcus aureus, Bacillus pyocyaneus, Bacillus coli, Bacillus proteus and physiological saline control groups. On 135 days after injection, distortion product otoacoustic emissions(DPOAE) was tested and all the samples were collected, which were examined with light and electronic microscopes. HSP70 related molecule expression in inner ear, nuclear factor (NF) kappa Bp65 characterization in mononuclear cell, anti-KP antibody and anti-membranous labyrinth proteins (MLP) were examined. RESULTS: No nuclear transfer of NF kappa Bp65 was observed in any animal. Anti-KP antibody was detected in 30% (3/10) of Staphylococcus aureus group, 29% (2/7) of KP group, 33% (3/9) of Bacillus pyocyaneus group and 10% (1/10) of control group. Anti-MLP antibody was created in 20% (2/10) of Staphylococcus aureus group, 20% (2/10) of KP group, one each in Bacillus pyocyaneus group and control group respectively. Double positive antibody against KP and MLP were found in Staphylococcus aureus group and KP group. When analyzed with Western blot, all the positive bands were small molecules including strongest 26,000-30,000, medium degree 38,000-41,000 and weak 46,000-50,000 except for 68,000 in one case. There was only one significant DPOAE amplification decrease at 1,625 Hz (2f1-f2) in left ear of Bacillus pyocyaneus group and right ear of Bacillus proteus group. No abnormal phenomenon was found in inner ear both under light microscope and electronic microscope. No significant expression of HSP70 was observed in inner ears. CONCLUSION: No long-term heat shock response related to HSP70 existed in the inner ear and the immune inner ear damage may be caused by multiplefactors.

Animals↗

PubMed1999

Transformation blocks differentiation-induced inhibition of serum response factor interactions with serum response elements.

The differentiation of nontransformed 3T3T mesenchymal stem cells is a multistep process that is associated with the progressive repression of mitogenic responsiveness to serum growth factors that ultimately results in expression of the terminally differentiated adipocyte phenotype. The repression of serum-induced mitogenesis by differentiation correlates with repression of the serum-inducible transcription of junB and c-fos. In contrast, the differentiation of neoplastically transformed cells does not repress mitogenic responsiveness or junB or c-fos inducibility. Because the junB and c-fos promoters both contain serum response elements (SREs), the current studies tested the possibility that differentiation might repress the ability of serum response factor (SRF) to bind to the SRE in normal cells but not in transformed cells. We now report that differentiation represses SRE serum inducibility using nontransformed cells transiently transfected with pjunB SRE thymidine kinase/chloroamphenicol acetyltransferase (SREtk/CAT) or pc-fos SREtk/CAT containing an intact SRF-binding domain. Adipocyte differentiation of nontransformed cells also markedly represses the ability of SRF to bind to the junB SRE, the c-fos SRE, and other SREs, as determined by mobility shift and gel supershift assays, without affecting the DNA binding characteristics of the nuclear protein SP-1. By comparison, the ability of SRF to bind SRE is not repressed by the differentiation of SV40 large T antigen-transformed 3T3T cells. The results further establish that adipocyte differentiation blocks the nuclear localization of SRF, thus preventing its interaction with SREs in nontransformed cells but not in transformed cells.

Adipocytes↗

PubMed1999

Study of chemical species of iodine in human liver.

The distribution and chemical species of iodine in various subcellular fractions of human liver were studied by using epithermal neutron activation analysis combined with chemical and biochemical separation techniques, such as gradient centrifugation and gel chromatography. It was found that the total iodine content orders in various subcellular fractions is as follows: nuclei > cytosol > mitochondria > lysosome > microsome. In the lysosomal fraction, iodine is mainly bound to macromolecules, whereas in the nuclei and mitochondrial fractions, mainly with lower-molecular-weight organic compounds. In the cytosol fraction, iodine is combined with three proteins, in which iodine is chiefly bound with mid- and high-molecular-weight proteins.

Chromatography, Gel↗

PubMed1999

Comparison of the chromium distribution in organs and subcellular fractions of normal and diabetic rats by using enriched stable isotope Cr-50 tracer technique.

The enriched stable isotope 50Cr(III) tracer technique combined with neutron activation analysis was used to examine the intracellular distribution of Cr(III) in the liver, pancreas, testes, and kidney homogenates of both normal and diabetic rats. Our new results showed that the nucleic fraction has the highest Cr concentration in the liver cell of both normal and diabetic rats. The diabetic rats retain more Cr in the mitochondrial and lysosomal fractions of liver homogenate than the normal. This is likely an indication of chromium participating in the glucose or lipid metabolism to compensate the low level of insulin in the body of diabetic rats. The concentrations of Cr in the subcellular fractions of pancreas, testes, and kidney in the normal rats are higher than those in the diabetic rats, which favor the hypothesis that Cr(III) plays its biological function via interaction with the insulin-sensitive tissues or enhancement of the sensitivity of the insulin receptor.

Animals↗

PubMed1999

Kinetics of tumor necrosis factor alpha in plasma and the cardioprotective effect of a monoclonal antibody to tumor necrosis factor alpha in acute myocardial infarction.

BACKGROUND: Inflammation plays a critical role in acute myocardial infarction (AMI) and tumor necrosis factor alpha (TNF-alpha) is a potent inflammatory trigger. This study was designed to examine the kinetics of TNF-alpha in plasma in patients with AMI and the potential benefit of inhibition of TNF-alpha monoclonal antibody in AMI. METHODS AND RESULTS: TNF-alpha levels in plasma were measured in 42 patients with AMI. TNF-alpha levels were elevated at 4 hours after onset of chest pain and declined to control values at 48 hours. TNF-alpha levels were higher in patients with Killip III and IV than in those with Killip I and II (P <.01). To examine the pathogenic role of TNF-alpha, New Zealand White rabbits were treated with buffer or a TNF-alpha monoclonal antibody before left anterior descending artery (LAD) ligation. Treatment with the TNF-alpha monoclonal antibody decreased area of necrosis, number of circulating endothelial cells, and lipid peroxidation product malonaldehyde bis(dimethyl acetal). There was a significant correlation of TNF-alpha levels with peak CK-MB in AMI patients, and area of necrosis, MDA, and circulating endothelial cells in rabbits (all P <.05). CONCLUSIONS: TNF-alpha release early in the course of AMI contributes to myocardial injury and dysfunction. Treatment with the monoclonal antibody against TNF-alpha can be cardioprotective, particularly in the setting of heart failure in patients with AMI.

Adult↗

PubMed1999

Does thin filament compliance diminish the cross-bridge kinetics? A study in rabbit psoas fibers.

The effect of thin filament compliance on our ability to detect the cross-bridge kinetics was examined. Our experiment is based on the facts that in rabbit psoas the thin filament (1.12 micrometer) is longer than half the thick filament length (0.82 micrometer) and that the thick filament has a central bare zone (0.16 micrometer). Consequently, when sarcomere length is increased from 2.1 to 2.4 micrometer, the same number of cross-bridges is involved in force generation but extra series compliance is introduced in the I-band. Three apparent rate constants (2pia, 2pib, and 2pic) were characterized by sinusoidal analysis at pCa 4.66. Our results demonstrate that 2pia and 2pib increased 13-16% when sarcomere length was increased from 2.0 to 2.5 micrometer, and 2pic decreased slightly (9%). This slight decrease can be explained by compression of the lattice spacing. These observations are at variance with the expectation based on increased series compliance, which predicts that the rate constants will decrease. We also determined compliance of the I-band during rigor. I-band compliance during rigor induction was 35% of sarcomere compliance at sarcomere length 2.4 micrometer, and 24% at sarcomere length 2.1 micrometer. We conclude that the presence of thin filament compliance does not seriously interfere with our ability to detect cross-bridge kinetics using sinusoidal analysis.

Animals↗

PubMed1999

HLA-DRB1 leprogenic motifs in nigerian population groups.

Amino acid residues involved in the peptide binding groove of HLA-DRB1 alleles were examined in three Nigerian ethnic groups with leprosy (n = 287) and 170 controls to determine the role of DRB1 alleles in disease outcome with Mycobacterium leprae. Nine positively charged motifs and two others with neutral charge to the binding groove were detected. These motifs occurred more frequently in leprosy (leprogenic) than was expected by chance (P < 0.0001). In contrast, five motifs with net negative or 'modified' neutral charges to the pocket were negatively associated with leprosy. We conclude that clinical outcome of infection with M. leprae is largely determined by a shared epitope in DRB1 alleles marked by several motifs. These motifs occur in otherwise normal DRB1 alleles, characterized by net positive or neutral charges in the binding groove. We hypothesize that these polarities cause poor binding of DRB1 to M. leprae. On presentation, the signal via the T cell receptor results in muted cell-mediated immunity. The resulting response translates to various forms of leprosy depending on degree of charge consonance between M. leprae and host DRB1 allele. Other factors within or without the HLA complex, such as the T cell receptor repertoire, may also influence the resulting disease.

Adolescent↗

PubMed1999

Granulocyte-macrophage colony-stimulating factor gene transfer to dendritic cells or epidermal cells augments their antigen-presenting function including induction of anti-tumor immunity.

Dendritic antigen-presenting cells derived from epidermis (Langerhans cells), bone marrow, and peripheral blood can present a wide variety of antigens, including tumor-associated antigens, for various immune responses. The development and function of dendritic cells is dependent upon a number of cytokines including granulocyte-macrophage-colony-stimulating factor. For example, Langerhans cells can present tumor-associated antigens for the induction of substantial in vivo anti-tumor immunity but only after activation in vitro by granulocyte-macrophage-colony-stimulating factor. Thus, we reasoned that insertion of a cDNA for granulocyte-macrophage-colony-stimulating factor into dendritic antigen-presenting cells may allow for autocrine stimulation and increased antigen-presenting capability. To test this possibility, we utilized an adenovirus vector to insert a cDNA for murine granulocyte-macrophage-colony-stimulating factor into the dendritic cell lines XS52-4D and XS106 (derived from neonatal mouse epidermis), bone marrow-derived dendritic cells, and epidermal cells that contain Langerhans cells. Infection of each of these cell types resulted in release of abundant quantities of granulocyte-macrophage-colony-stimulating factor. XS52-4D and XS106 cells infected with adenovirus granulocyte-macrophage-colony-stimulating factor exhibited prolonged dendrites and greater expression of major histocompatibility complex class II molecules and CD86 compared with cells infected with a null vector. Granulocyte-macrophage-colony-stimulating factor cDNA-containing XS cells, bone marrow-derived dendritic cells, and epidermal cells had more potent alloantigen presenting capability than cells infected with a null vector. Most importantly, granulocyte-macrophage-colony-stimulating factor gene-transferred epidermal cells were able to present tumor-associated antigens for in vivo anti-tumor immunity against challenge with the S1509a spindle-cell tumor whereas null vector-infected cells were unable to prime for immunity. These results suggest that introduction of a cDNA for granulocyte-macrophage-colony-stimulating factor into dendritic cells may be an effective means to augment their antigen-presenting capability and that granulocyte-macrophage-colony-stimulating factor gene-transfer- red epidermal cells may be useful in tumor vaccination strategies.

Animals↗

PubMed1999

Role of p53 gene mutations in human esophageal carcinogenesis: results from immunohistochemical and mutation analyses of carcinomas and nearby non-cancerous lesions.

In order to characterize p53 alterations in esophageal cancer and to study their roles in carcinogenesis, we performed gene mutation and immunohistochemical analysis on 43 surgically resected human esophageal specimens, which contain squamous cell carcinoma (SCC) and adjacent non-cancerous lesions, from a high-incidence area of Linzhou in Henan, China. A newly developed immunohisto-selective sequencing (IHSS) method was used to enrich the p53 immunostain-positive cells for mutation analysis. p53 gene mutations were detected in 30 out of 43 (70%) SCC cases. Among 29 SCC cases that were stained positive for p53 protein, 25 (86%) were found to contain p53 mutations. In five cases of SCC with homogeneous p53 staining, the same mutation was observed in samples taken from four different positions of each tumor. In a well differentiated cancer nest, p53 mutation was detected in only the peripheral p53-positive cells. In tumor areas with heterogeneous p53 staining, either the area stained positive for p53 had an additional mutation to the negatively stained area or both areas lacked any detectable p53 mutation. In the p53-positive non-cancerous lesions adjacent to cancer, p53 mutations were detected in seven out of 16 (47%) samples with basal cell hyperplasia (BCH), eight out of 12 (67%) samples with dysplasia (DYS), and six out of seven (86%) samples with carcinoma in situ (CIS). All mutations found in lesions with DYS and CIS were the same as those in the nearby SCC. In seven cases of BCH containing mutations, only three had the same mutations as the nearby SCC. The results suggest that p53 mutation is an early event in esophageal carcinogenesis occurring in most of the DYS and CIS lesions, and cells with such mutations will progress to carcinoma, whereas the role of p53 mutations in BCH is less clear.

Adult↗

PubMed1999

Proliferation response to interleukin-2 and Jak/Stat activation of T cells immortalized by human T-cell lymphotropic virus type 1 is independent of open reading frame I expression.

Human T-cell lymphotropic virus type 1 (HTLV-1), a complex retrovirus, encodes a hydrophobic 12-kD protein from pX open reading frame (ORF) I that localizes to cellular endomembranes and contains four minimal SH3 binding motifs (PXXP). We have demonstrated the importance of ORF I expression in the establishment of infection and hypothesize that p12(I) has a role in T-cell activation. In this study, we tested interleukin-2 (IL-2) receptor expression, IL-2-mediated proliferation, and Jak/Stat activation in T-cell lines immortalized with either wild-type or ORF I mutant clones of HTLV-1. All cell lines exhibited typical patterns of T-cell markers and maintained mutation fidelity. No significant differences between cell lines were observed in IL-2 receptor chain (alpha, beta, or gamma(c)) expression, in IL-2-mediated proliferation, or in IL-2-induced phosphorylated forms of Stat3, Stat5, Jak1, or Jak3. The expression of ORF I is more likely to play a role in early HTLV-1 infection, such as in the activation of quiescent T cells in vivo.

Cell Line, Transformed↗

PubMed1999

Insulin-like growth factor I in skeletal muscle after weight-lifting exercise in frail elders.

To assess muscle remodeling and functional adaptation to exercise and diet interventions, 26 men and women aged 72-98 yr underwent a vastus lateralis biopsy before and after placebo control condition, and progressive resistance training, multinutrient supplementation, or both. Type II atrophy, Z band, and myofibril damage were present at baseline. Combined weight lifting and nutritional supplementation increased strength by 257 +/- 62% (P = 0.0001) and type II fiber area by 10.1 +/- 9.0% (P = 0.033), with a similar trend for type I fiber area (+12.8 +/- 22.2%). Exercise was associated with a 2. 5-fold increase in neonatal myosin staining (P = 0.0009) and an increase of 491 +/- 137% (P < 0.0001) in IGF-I staining. Ultrastructural damage increased by 141 +/- 59% after exercise training (P = 0.034). Strength increases were largest in those with the greatest increases in myosin, IGF-I, damage, and caloric intake during the trial. Age-related sarcopenia appears largely confined to type II muscle fibers. Frail elders respond robustly to resistance training with musculoskeletal remodeling, and significant increases in muscle area are possible with resistance training in combination with adequate energy intakes.

Aged↗

PubMed1999

The impact of codon 54 variation in intestinal fatty acid binding protein gene on the pathogenesis of diabetes mellitus in Chinese.

OBJECTIVE: To investigate whether or not the intestinal fatty acid binding protein gene (FABP2)-Ala54Thr variation is related to non-insulin dependent diabetes mellitus (NIDDM), obesity, dyslipidemia and glucose stimulated insulin secretion (GSIS) in Chinese. METHODS: The FABP2-Ala54Thr variation was detected by PCR/Hhal digestion in 231 Chinese subjects (116 with normal glucose tolerance (NGT), 54 with impaired glucose tolerance (IGT) and 61 with NIDDM). Plasma glucose, insulin and C-peptide levels before and after 75 g glucose load as well as fasting lipid profile were determined. RESULTS: (1) The Ala54 and Thr54 allele frequencies in Chinese were 0.71 and 0.29 respectively; (2) The FABP2-Ala54Thr variation was neither associated with fasting and post-challenged plasma glucose levels nor with NIDDM; (3) This variation was neither associated with fasting lipid profile nor with obesity; (4) The IGT subjects with genotype Thr54(+) (Thr54 homozygotes and heterozygotes) had lower fasting, 2-hour and total C-peptide levels and smaller AUC representing lesser C-peptide secretion after glucose challenge than those with genotype Thr54(-) (Ala54 homozygotes) (P = 0.04, 0.03, 0.01 and 0.01 respectively). The serum insulin levels changed in the same tendency. CONCLUSIONS: The glucose stimulated insulin secretion (GSIS) reserve of islet beta-cells is more limited in subjects with FABP2-Thr54(+) genotype than in those with FABP2-Thr54(-) genotype. It suggests that FABP2-codon 54 variation might contribute to the insufficient insulin secretion in the development of NIDDM in Chinese.

Alanine↗