PubMed Health⌕ Search

Biomedical subjects

Yan Wang

Publications and source records attributed to Yan Wang.

At least 343 records · Page 19Linked to original sources
PubMed2004

Dipeptidyl aspartyl fluoromethylketones as potent caspase inhibitors: SAR of the N-protecting group.

This article describes the synthesis and biological evaluation of a group of N-protected Val-Asp-fmk as caspase inhibitors. The protecting group was found to contribute to caspase-3 inhibiting activity, and compounds with a large group such as Cbz are more active than compounds with a small group such as Ac. Compounds with more hydrophobic protecting groups were found to be more active in cell apoptosis protection assays, probably due to increased cell permeability. MX1122, 2,4-di-Cl-Cbz-Val-Asp-fmk, is identified as a potent broad-spectrum caspase inhibitor and is selective for caspases versus other proteases, with good activity in the cell apoptosis protection assays as well as good efficacy in the mouse liver apoptosis model.

Amino Acid Chloromethyl Ketones↗
PubMed2004

[Anterior cervical diskectomy and fusion with allograft and internal fixation].

OBJECTIVE: To evaluate the effect of cylindrical titanium mesh packing cancellous allograft in the anterior cervical fusion for the cervical spondylosis with anterior titanium plate. METHODS: Ninety-eight patients with cervical spondylosis underwent diskectomy and cancellous allograft contained in cylindrical titanium mesh enhanced by anterior titanium plate system. Sixty-four patients were followed up clinically and radiographically. The mean follow-up time was (15.2 +/- 1.7) months. JOA scores and Nurick myelopathy grading system were used for clinical assessment. Roentgenograms were analyzed to identify the stability of fused levels. RESULTS: In all patients of 98 cases, the wounds were normally healed without acute or chronic infection. In statistical analysis of 64 patients followed up, the mean JOA scores was (11.6 +/- 1.8) preoperatively and improved to (16.0 +/- 1.2) at final follow-up (P < 0.05). And the mean Nurick grades were (2.7 +/- 0.7) and (0.7 +/- 0.8) before and after surgery respectively (P < 0.05). The X-ray films demonstrated that no meshes were found displacing or subsiding. New bone formation occurred in the back of meshes at 5 months after surgery. The final follow-up fusion rate was 95%. CONCLUSION: The cancellous allograft impacted into titanium meshes for cervical fusion has gained excellent or good results clinically and radiographically in short term follow-up.

Bone Transplantation↗
PubMed2004

[Freeze-dried allograft of posterior spinal fusion in patients with scoliosis].

OBJECTIVE: To observe the effectiveness and safety of allograft in posterior spinal fusion in patients with scoliosis. METHODS: 41 cases of 54 scoliosis patients with allograft for spinal fusion were followed up. The mean follow-up time is 16 months. Foreign body reaction was studied clinically and fusion status was assessed radiographically. RESULTS: There was no foreign body reaction significantly in all patients. Acute deep wound infection happened in one patient and no chronic deep wound infection occurred. There was no disease transferred by allograft in followed patients. New bone formation appeared after 4 months postoperatively in radiogram. At final follow-up, the mean angle of 3.4 degrees lost and minimal -1 degrees and maximal 6 degrees . Implants were fastened and did not loosen and fracture. CONCLUSIONS: Allograft for posterior spinal fusion in scoliosis patients was useful and safe.

Adolescent↗
PubMed2004

p53 polymorphism in human papillomavirus-associated Kazakh's esophageal cancer in Xinjiang, China.

AIM: To investigate the relationship between p53 codon 72 polymorphism and human papillomavirus (HPV) type 16 infection in Kazakh's esophageal cancer (EC) in Xinjiang, China. METHODS: Encoding regions of p53 codon 72 and HPV-16 E6 were amplified by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and polymerase chain reaction (PCR) methods using pairs of primary esophageal squamous cell carcinoma (SCC) tissue and corresponding normal mucosa, which were collected from 104 patients of Kazakh in Xinjiang, China. RESULTS: Only arginine allele was detected in 70.1% (39/55) of HPV-16-E6- positive cases but only in 40.8% (20/49) of HPV-16-E6-negative cases (P<0.05; OR, 3.53; 95% CI, 1.57-7.98). In contrast, such a significant correlation between p53 polymorphism and HPV infection was not evident in corresponding normal mucosae. The allele frequency of Arg allele in cancer cases (0.68) was higher than that in normal mucosa samples (0.54) (P<0.05; OR, 1.80; 95% CI, 1.21-2.69). CONCLUSION: p53 codon 72 Arg homozygous genotype is one of the high-risk genetic factors for HPV-associated SCC of Kazakh. Individuals carrying Arg allele compared to those with Pro allele have an increased risk for esophageal SCC.

Amino Acid Substitution↗
PubMed2004

Regulated transcripts in the hippocampus following transections of the entorhinal afferents.

Based on the data from a cDNA microarray experiment which was carried out to screen the differential expressed genes in the rat hippocampus 10 days after removal of the entorhinal afferents, we confirmed the increase of expression of eight transcripts encoding protein osteonectin, thymosin-beta4, gelsolin, MHC I, MHC II, beta2-microglobulin, and interferon-gamma receptor using Northern blot. In situ hybridization revealed that the up-regulation of all these 8 transcripts localized specifically in the denervated target areas, the hippocampal stratum lacunosum-moleculare, and the dentate outer molecular layer. The results suggest that these molecules may have roles in the plasticity events in the hippocampus after entorhinal deafferentation.

Adaptation, Physiological↗
PubMed2004

[A novel missense mutation, K124N, in the troponin T gene of Chinese populations with hypertrophic cardiomyopathy].

OBJECTIVE: To study the cardiac troponin T (TNNT2) gene mutation in Chinese patients with hypertrophic cardiomyopathy (HCM) and to analyze the correlation between the genotype and phenotype. METHODS: Specimens of peripheral blood were collected from 71 unrelated Chinese probands with HCM, aged 40 +/- 18. The genome DNA was extracted. Single-strand conformation polymorphism gel analysis of the polymerase chain reaction-amplified products was conducted to search for mutations in the exons 8, 9, 10, 11, and 16 of the TNNT2 gene. Relevant clinical data were collected. One hundred normal persons, aged 44 +/- 14, were used as controls. RESULTS: A missense mutation, K124N, in the exon 9 of the TNNT2 gene was identified in a 41-year-old female patient with HCM and failed to be detected in the 100 normal controls, which suggested the disease-causing mutation. The patient began to have the symptoms of chest distress and palpitation since the age of 38, presented moderate hypertrophy of the intraventricular septum, and did not have a family history of sudden cardiac death. CONCLUSION: A novel missense mutation of troponin T gene has been identified. Mutation in tail part of cardiac troponin T, essential for it's binding function, causes the disease of HCM. Correlative analysis confirms the genetic heterogeneity of the disease.

Adult↗
PubMed2004

Real-time analysis of endosomal lipid transport by live cell scintillation proximity assay.

A scintillation proximity assay has been developed to study the endosomal trafficking of radiolabeled cholesterol in living cells. Mouse macrophages were cultured in the presence of tritiated cholesterol and scintillant microspheres. Microspheres were taken up by phagocytosis and stored in phagolysosomes. Absorption of tritium beta particles by the scintillant produces light signals that can be measured in standard scintillation counters. Because of the short range of tritium beta particles and for geometric reasons, scintillant microspheres detect only that fraction of tritiated cholesterol localized inside phagolysosomes or within a distance of approximately 600 nm. By incubating cultures in a temperature-controlled microplate reader, the kinetics of phagocytosis and cholesterol transport could be analyzed in near-real time. Scintillation signals were significantly increased in response to inhibitors of lysosomal cholesterol export. This method should prove a useful new tool for the study of endosomal trafficking of lipids and other molecules.

Animals↗
PubMed2004

A secreted protein from the human hookworm necator americanus binds selectively to NK cells and induces IFN-gamma production.

Parasitic helminths induce chronic infections in their hosts although, with most human helminthiases, protective immunity gradually develops with age or exposure of the host. One exception is infection with the human hookworm, Necator americanus, where virtually no protection ensues over time. Such observations suggest these parasites have developed unique mechanisms to evade host immunity, leading us to investigate the role of the excretory/secretory (ES) products of adult N. americanus in manipulating host immune responses. Specifically, we found that a protein(s) from ES products of adult N. americanus bound selectively to mouse and human NK cells. Moreover, incubation of purified NK cells with N. americanus ES products stimulated the production of augmented (4- to 30-fold) levels of IFN-gamma. This augmentation was dependent on the presence of both IL-2 and IL-12 and was endotoxin-independent. This is the first report of a pathogen protein that binds exclusively to NK cells and the first report of a nematode-derived product that induces abundant levels of cytokines from NK cells. Such an interaction could provide a means of cross-regulating deleterious Th2 immune responses in the host, thereby contributing to the long-term survival of N. americanus.

Animals↗
PubMed2004

Hepatopoietin interacts directly with COP9 signalosome and regulates AP-1 activity.

Hepatopoietin (HPO)/augmenter of liver regeneration (ALR) is a specific hepatotrophic growth factor, which plays a key role in liver regeneration. Our previous study indicated that HPO executes its function by an inter-reactive network of the autocrine, paracrine and endocrine pathways. Recently, we have demonstrated that intracellular HPO interacts with Jun activation domain-binding protein 1 (JAB1) and leads to potentiation of activating protein-1 (AP-1) activity in a MAPK independent fashion. JAB1 is the fifth subunit of the COP9 signalosome (CSN), which is first identified as a suppressor of plant morphogenesis. A protein complex kinase activity associated with the CSN has been reported but not identified yet. In this report, we investigated further the association of HPO with the whole CSN. HPO exists in a complex with the eight-component CSN, both when purified from glycerol gradient centrifugation and when reciprocal immunoprecipitated from the lysates of transfected COS-7 cells. Intracellular HPO colocalizes with endogenous CSN in nucleus of hepatic cells. In addition, intracellular function of HPO that increases the phosphorylation of c-Jun leading to potentiate the AP-1 activity is inhibited by curcumin, a potent inhibitor of CSN-associated kinase. Taken together, these results elucidate a novel relationship of intracellular growth factor, HPO with large protein complex, CSN, which suggests a possible linkage between CSN and liver regeneration.

Animals↗
PubMed2004

Differential regulation of K8 gene expression in immediate-early and delayed-early stages of Kaposi's sarcoma-associated herpesvirus.

KSHV-encoded bZip protein, namely K8, is a regulatory protein with multiple functions in immediate-early and delayed-early stages of viral life cycle. Here we report that K8 gene is expressed in both immediate-early and delayed-early phases and the transcription in different phases is controlled by distinct promoters, yielding two transcripts, an immediate-early mRNA of 1.5 kb and a delayed-early mRNA of 1.3 kb. The transcription from the immediate-early promoter is inducible by sodium butyrate or 12-O-tetradecanoylphorbol-13-acetate (TPA), but not responsive to ORF50 (Rta). The delayed-early promoter of K8 shows little response to sodium butyrate and TPA, but can be fully induced by ORF50 (Rta). In the immediate-early promoter, a 20-bp region containing two consensus Sp-1 binding sites was found to be crucial for the basal transcription and sodium butyrate induction of the promoter. In addition, mutagenesis analyses identified three ORF50 (Rta) responsive elements (RREs) in the delayed-early promoter and their roles in ORF50-dependent transactivation were investigated. The differential regulation of K8 gene expression may represent a strategy in that the virus fine-tunes the levels of K8 protein in different stages or for distinct functions. The elucidation of K8 gene expression regulation helps in understanding roles of K8 in viral replication and pathogenicity.

B-Lymphocytes↗
PubMed2004

Cingulate cortical cells projecting to monkey frontal eye field and primary motor cortex.

We compared the distribution of cingulate cortical cells projecting to the frontal eye field (FEF) and primary motor cortex (MI) using a multiple retrograde labeling technique. Two fluorescent tracers were injected into physiologically identified FEF and MI in each monkey. The location of cells projecting to the forelimb area of MI served to identify the rostral (CMAr) and caudal (CMAc) cingulate motor areas. We found two foci of cells projecting to the FEF: rostral (CEFr) and caudal (CEFc) cingulate eye field. The CEFr was located rostral to the CMAr, while the CEFc was located rostro-ventral to the CMAc. Cells projecting to the FEF and MI scarcely overlapped, indicating that each area receives different sets of information from the cingulate cortex.

Amidines↗
PubMed2004

Gene expression profiles at diagnosis in de novo childhood AML patients identify FLT3 mutations with good clinical outcomes.

Fms-like tyrosine kinase 3 (FLT3) mutations are associated with unfavorable outcomes in children with acute myeloid leukemia (AML). We used DNA microarrays to identify gene expression profiles related to FLT3 status and outcome in childhood AML. Among 81 diagnostic specimens, 36 had FLT3 mutations (FLT3-MUs), 24 with internal tandem duplications (ITDs) and 12 with activating loop mutations (ALMs). In addition, 8 of 19 specimens from patients with relapses had FLT3-MUs. Predictive analysis of microarrays (PAM) identified genes that differentiated FLT3-ITD from FLT3-ALM and FLT3 wild-type (FLT3-WT) cases. Among the 42 specimens with FLT3-MUs, PAM identified 128 genes that correlated with clinical outcome. Event-free survival (EFS) in FLT3-MU patients with a favorable signature was 45% versus 5% for those with an unfavorable signature (P = .018). Among FLT3-MU specimens, high expression of the RUNX3 gene and low expression of the ATRX gene were associated with inferior outcome. The ratio of RUNX3 to ATRX expression was used to classify FLT3-MU cases into 3 EFS groups: 70%, 37%, and 0% for low, intermediate, and high ratios, respectively (P < .0001). Thus, gene expression profiling identified AML patients with divergent prognoses within the FLT3-MU group, and the RUNX3 to ATRX expression ratio should be a useful prognostic indicator in these patients.

Acute Disease↗
PubMed2004

Characterization of TAT-mediated transport of detachable kinase substrates.

The conjugation of peptides derived from the HIV TAT protein to membrane-impermeant molecules has gained wide acceptance as a means for intracellular delivery. Numerous studies have addressed the mechanism of uptake and kinetics of TAT translocation, but the cytosolic concentrations and bioavailability of the transported cargo have not been well-characterized. The current paper utilizes a microanalytical assay to perform quantitative single-cell measurements of the concentration and accessibility of peptide-based substrates for protein kinase B (PKB) and Ca(2+)/calmodulin-activated kinase II. The substrate peptide and TAT were conjugated through a releasable linker, either a disulfide or photolabile bond. Free substrate peptide concentrations of approximately 10(-20)-10(-18) moles were attainable in a cell when substrates were delivered utilizing these conjugates. The substrate peptides delivered as a disulfide conjugate were often present in the cytosol as several oxidized forms. Brief exposure of cells loaded with the photolabile conjugates to UVA light released free substrate peptide into the cytosol. Substrate peptide delivered by either conjugate was accessible to cytosolic kinase as demonstrated by the efficient phosphorylation of the peptide when the appropriate kinase was active. After incubation of the conjugated substrate with cells, free, kinase-accessible substrate was detectable in less than 30 min. Release of the majority of loaded substrate peptide from sequestered organelles occurred within 1 h. The utility of the photocleavable conjugates was demonstrated by measuring the activation of PKB in 3T3 cells after addition of varying concentrations of platelet-derived growth factor.

Animals↗
PubMed2004

Novel and potent transforming growth factor beta type I receptor kinase domain inhibitor: 7-amino 4-(2-pyridin-2-yl-5,6-dihydro-4H-pyrrolo[1,2-b]pyrazol-3-yl)-quinolines.

A novel series of 7-amino 4-(2-pyridin-2-yl-5,6-dihydro-4H-pyrrolo[1,2-b]pyrazol-3-yl)-quinolines was synthesized and their TbetaR-1 inhibitory, p38 MAPK inhibitory, and TbetaR-1-dependent cellular activity were evaluated. Compound 5a was found to be a highly potent in the enzyme assay and TbetaR-1-dependent cellular assays. In addition, dimer (4g), with a urea linker, shows a similar enzyme and cellular activity despite a bulky substitution.

Activin Receptors, Type I↗
PubMed2004

Prenatal estrogen exposure differentially affects estrogen receptor-associated proteins in rat testis gonocytes.

We previously reported that gonocytes from 3-day-old rat testes proliferate in response to estradiol. In the present study, we found that purified gonocytes contained the mRNAs of estrogen receptor beta (ERbeta) and the chaperones Hsp90, p23, and Cyp40, but no inducible Hsp70. Immunoblot analysis showed high levels of ERbeta, Hsp90, p23, Cyp40, and the constitutive Hsc70 in gonocytes. Prenatal exposure to the estrogenic compounds diethylstilbestrol, bisphenol A, genistein, and coumestrol led to significantly increased Hsp90 mRNA levels in testis, but not p23 and Cyp40. In situ hybridization analysis indicated that Hsp90 mRNA was prominent in gonocytes, where it was increased following phytoestrogen exposure, whereas bisphenol A induced a more generalized increase throughout the testis. Immunoblot analysis of testicular extracts demonstrated that Hsp90 protein levels were significantly increased following estrogen exposure, and immunohistochemical analysis indicated that this increase occurred predominantly in gonocytes. By contrast, no change was observed in the expression of Cyp40, p23, and ERbeta, whereas Hsc70 was increased by bisphenol A only. Using an antibody and reverse transcriptase-polymerase chain reaction probes specific for Hsp90alpha, we subsequently confirmed that Hsp90alpha was primarily expressed in gonocytes, and that it was increased following estrogen exposure. Hsp90 immunolocalization in fetal and prepubertal testes showed an increased expression in fetal gonocytes upon estrogen exposure, but no difference in the subsets of Hsp90-positive germ cells in prepubertal testes. These results demonstrate that prenatal estrogen exposure specifically affects Hsp90 expression in gonocytes. Considering the interaction of Hsp90 with several signaling molecules, changes in its expression levels may lead to subsequent changes in gonocyte development.

Aging↗
PubMed2004

DNA microarray probe preparation by gel isolation nested PCR.

To develop a simplified method that can rapidly prepare DNA microarray probes in a massive scale, a lambda phage genomic DNA-fragments library was constructed for the microarray-probes collection. Four methods of DNA band recovery from the first PCR products were tested and compared. The DNA microarray probes were collected by a novel method of nested PCR that was mediated by gel isolation of the first PCR products. This method was named GIN-PCR. The probes that were prepared by this GIN-PCR technique were used as subjects to fabricate a DNA microarray. The results showed that a wooden toothpick was superior to the other 3 methods, since this technique can steadily transfer the DNA bands as the template of the second PCR after the first PCR. A group of probes were successfully collected and DNA microarrays were constructed using these probes. Hybridization results demonstrated that this technique of DNA recovery and probe preparation was rapid, efficient, and effective. We developed a cost-effective and less labor-intensive method for DNA microarray probe preparation by nested PCR that is mediated by wooden toothpick transfer of the DNA bands in the gel after electrophoresis.

Bacteriophage lambda↗
PubMed2004

Identification of the pollen determinant of S-RNase-mediated self-incompatibility.

Many flowering plants have adopted self-incompatibility mechanisms to prevent inbreeding and promote out-crosses. In the Solanaceae, Rosaceae and Scrophulariaceae, two separate genes at the highly polymorphic S-locus control self-incompatibility interactions: the S-RNase gene encodes the pistil determinant and the previously unidentified S-gene encodes the pollen determinant. S-RNases interact with pollen S-allele products to inhibit the growth of self-pollen tubes in the style. Pollen-expressed F-box genes showing allelic sequence polymorphism have recently been identified near to the S-RNase gene in members of the Rosaceae and Scrophulariaceae; but until now have not been directly shown to encode the pollen determinant. Here we report the identification and characterization of PiSLF, an S-locus F-box gene of Petunia inflata (Solanaceae). We show that transformation of S1S1, S1S2 and S2S3 plants with the S2-allele of PiSLF causes breakdown of their pollen function in self-incompatibility. This breakdown of pollen function is consistent with 'competitive interaction', in which pollen carrying two different pollen S-alleles fails to function in self-incompatibility. We conclude that PiSLF encodes the pollen self-incompatibility determinant.

Alleles↗