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Biomedical subjects

Yi Wang

Publications and source records attributed to Yi Wang.

At least 91 records · Page 5Linked to original sources

Skeletal myogenesis by human embryonic stem cells.

We have examined the myogenic potential of human embryonic stem (hES) cells in a xeno-transplantation animal model. Here we show that precursors differentiated from hES cells can undergo myogenesis in an adult environment and give rise to a range of cell types in the myogenic lineage. This study provides direct evidences that hES cells can regenerate both muscle and satellite cells in vivo and are another promising cell type for treating muscle degenerative disorders in addition to other myogenic cell types.

Animals↗

New epitope peptides derived from hepatitis C virus (HCV) 2a which have the capacity to induce cytotoxic T lymphocytes in HLA-A2+ HCV-infected patients.

Because cytotoxic T lymphocytes (CTLs) play an important role in the specific immunotherapy of hepatitis C virus (HCV) infection, a series of CTL epitopes has been defined from HCV genotype 1a or 1b protein. Here, we attempted to identify HCV2a-derived epitopes that are capable of inducing HLA-A2-restricted and peptide-specific CTLs. Peripheral blood mononuclear cells (PBMCs) of HLA-A2+ HCV2ainfected patients or healthy donors were stimulated in vitro with each of the HCV2a-derived peptides, which were prepared based on the HLA-A2-binding motif, and their peptide-specific and HLA-A2-restricted cytotoxicities were examined. The HCV2a 432-441, HCV2a 716-724, and HCV2a 2251-2260 peptides were found to efficiently induce peptide-specific CTLs from the PBMCs of HLA-A2+ HCV2ainfected patients. Cytotoxicity was mainly mediated by CD8+ T cells in a HLA class I-restricted manner. These results indicate that the HCV2a 432-441, HCV2a 716-724, and HCV2a 2251-2260 peptides might be applicable for peptide-based immunotherapy of HLA-A2+ HCV2a-infected patients.

Amino Acid Sequence↗

Adrenomedullin regulates expressions of transforming growth factor-beta1 and beta1-induced matrix metalloproteinase-2 in hepatic stellate cells.

Adrenomedullin (AM), a peptide isolated from human pheochromocytoma, can be produced and secreted by various types of cells including hepatic stellate cells (HSCs), and its possible role in HSCs is not clear now. In the present study, the interactive regulation between transforming growth factor (TGF)-beta1 and AM and the effect of AM on TGF-beta1-induced matrix metalloproteinase (MMP)-2 expression in HSCs were investigated. TGF-beta1 and AM inhibited gene transcript level mutually (real-time reverse transcription-polymerase chain reaction). AM suppressed the protein expression level of TGF-beta1 (Western blot), but TGF-beta1 might have no effect on AM secretion level. MMP-2 protein expression in HSCs was increased in response to TGF-beta1, and upregulation of MMP-2 expression stimulated with TGF-beta1 was suppressed by AM in dose-dependent manner (Western blot). AM decreased the phosphorylation level of extracellular signal-regulated kinase (ERK) in HSCs treated with TGF-beta1, and TGF-beta1-induced MMP-2 expression was suppressed by adding Mitogen-activated protein Kinase/ERK (MEK) inhibitor U(0126) (Western blot)(.) Our results suggest that AM may intervene the activation of HSCs by inhibiting TGF-beta1 production and TGF-beta1-induced MMP-2 expression; AM may suppress the upregulation of MMP-2 expression induced by TGF-beta1 partially through ERK pathway.

Adrenomedullin↗

A computational approach to botanical drug design by modeling quantitative composition-activity relationship.

Herbal medicine has been successfully applied in clinical therapeutics throughout the world. Following the concept of quantitative composition-activity relationship, the presented study proposes a computational strategy to predict bioactivity of herbal medicine and design new botanical drug. As a case, the quantitative relationship between chemical composition and decreasing cholesterol effect of Qi-Xue-Bing-Zhi-Fang, a widely used herbal medicine in China, was investigated. Quantitative composition-activity relationship models generated by multiple linear regression, artificial neural networks, and support vector regression exhibited different capabilities of predictive accuracy. Moreover, the proportion of two active components of Qi-Xue-Bing-Zhi-Fang was optimized based on the quantitative composition-activity relationship model to obtain new formulation. Validation experiments showed that the optimized herbal medicine has greater activity. The results indicate that the presented method is an efficient approach to botanical drug design.

Algorithms↗

Segmented crystalline scintillators: empirical and theoretical investigation of a high quantum efficiency EPID based on an initial engineering prototype CsI(TI) detector.

Modern-day radiotherapy relies on highly sophisticated forms of image guidance in order to implement increasingly conformal treatment plans and achieve precise dose delivery. One of the most important goals of such image guidance is to delineate the clinical target volume from surrounding normal tissue during patient setup and dose delivery, thereby avoiding dependence on surrogates such as bony landmarks. In order to achieve this goal, it is necessary to integrate highly efficient imaging technology, capable of resolving soft-tissue contrast at very low doses, within the treatment setup. In this paper we report on the development of one such modality, which comprises a nonoptimized, prototype electronic portal imaging device (EPID) based on a 40 mm thick, segmented crystalline CsI(Tl) detector incorporated into an indirect-detection active matrix flat panel imager (AMFPI). The segmented detector consists of a matrix of 160 x 160 optically isolated, crystalline CsI(Tl) elements spaced at 1016 microm pitch. The detector was coupled to an indirect detection-based active matrix array having a pixel pitch of 508 microm, with each detector element registered to 2 x 2 array pixels. The performance of the prototype imager was evaluated under very low-dose radiotherapy conditions and compared to that of a conventional megavoltage AMFPI based on a Lanex Fast-B phosphor screen. Detailed quantitative measurements were performed in order to determine the x-ray sensitivity, modulation transfer function, noise power spectrum, and detective quantum efficiency (DQE). In addition, images of a contrast-detail phantom and an anthropomorphic head phantom were also acquired. The prototype imager exhibited approximately 22 times higher zero-frequency DQE (approximately 22%) compared to that of the conventional AMFPI (approximately 1%). The measured zero-frequency DQE was found to be lower than theoretical upper limits (approximately 27%) calculated from Monte Carlo simulations, which were based solely on the x-ray energy absorbed in the detector-indicating the presence of optical Swank noise. Moreover, due to the nonoptimized nature of this prototype, the spatial resolution was observed to be significantly lower than theoretical expectations. Nevertheless, due to its high quantum efficiency (approximately 55%), the prototype imager exhibited significantly higher DQE than that of the conventional AMFPI across all spatial frequencies. In addition, the frequency-dependent DQE was observed to be relatively invariant with respect to the amount of incident radiation, indicating x-ray quantum limited behavior. Images of the contrast-detail phantom and the head phantom obtained using the prototype system exhibit good visualization of relatively large, low-contrast features, and appear significantly less noisy compared to similar images from a conventional AMFPI. Finally, Monte Carlo-based theoretical calculations indicate that, with proper optimization, further, significant improvements in the DQE performance of such imagers could be achieved. It is strongly anticipated that the realization of optimized versions of such very high-DQE EPIDs would enable megavoltage projection imaging at very low doses, and tomographic imaging from a "beam's eye view" at clinically acceptable doses.

Biomedical Engineering↗

Polymorphisms in the two helicases ERCC2/XPD and ERCC3/XPB of the transcription factor IIH complex and risk of lung cancer: a case-control analysis in a Chinese population.

The transcription factor IIH (TFIIH) helicases ERCC2/XPD and ERCC3/XPB are responsible for opening the DNA strand around the lesion site during nucleotide excision repair process. Genetic variants in these two genes may be markers for interindividual variability in DNA repair capacity and thus predisposition to cancer risk. In this case-control study of 1,010 incident lung cancer cases and 1,011 age and sex frequency-matched cancer-free controls in a Chinese population, we genotyped eight tagging polymorphisms of ERCC2 and ERCC3 using the high-throughput Taqman platform to determine their associations with risk of lung cancer. Although none of the eight polymorphisms was individually associated with lung cancer risk, we found that genetic variants in ERCC2 and ERCC3 jointly contributed to lung cancer risk in a dose-response manner. Compared with those with 0 to 1 "at-risk" locus, subjects carrying >1 at-risk loci were at increased risk for lung cancer [adjusted odds ratio (OR), 1.29; 95% confidence interval (95% CI), 0.98-1.70 for 2 at-risk loci; adjusted OR, 1.38; 95% CI, 1.02-1.85 for 3 at-risk loci; and adjusted OR, 1.51; 95% CI, 1.09-2.10 for > or =4 at-risk loci, respectively; P(trend) = 0.015]. This combined effect was slightly more evident in young subjects (<60 years), males, current smokers, and those with family history of cancer, particularly for histologic type of adenocarcinomas. No evidence for interaction was found. These findings indicate that these tagSNPs of the ERCC2 and ERCC3 along with their surrounding regions may serve as biomarkers of susceptibility to lung cancer, which warrant further validation by other population-based and phenotypic studies to determine the biological relevance of these tagSNPs.

Adenocarcinoma↗

Sonographic feature extraction of cervical lymph nodes and its relationship with segmentation methods.

OBJECTIVE: The purpose of this study was to extract quantitative features for characterization of cervical lymph nodes on sonographic images and analyze the effect of a semiautomated segmentation method on the feature extraction. METHODS: Contours of 186 cervical lymph nodes on sonographic images were separately delineated by 2 radiologists (R1 and R2) and a semiautomated segmentation method. For each node, 10 kinds of sonographic features (including 3 parameters of size; 12 parameters of margin; 4 parameters of nodal border; 10 parameters of echogeneity; and 1 parameter of shape, echogenicity, medulla ratio, medulla distribution, vascular density, and vascular pattern, respectively) were quantified by a computerized scheme based on the segmented contour. Correlations between the quantitative parameter and the radiologists' consensus grading were computed to assess the effectiveness of these parameters. Concerning the 14 best correlated parameters, the effect of the segmentation stage on the feature extraction was estimated by comparing the parameter values calculated under different segmentations in terms of relative ultimate measurement accuracy. RESULTS: Good correlations between the computerized scheme and radiologists were seen in features of size, nodal border, shape, echogenicity, medulla ratio, medulla distribution, vascular density, and vascular pattern, whereas 10 of 12 parameters of margin features and 8 of 10 parameters of echogeneity features showed poor correlations. Paired t tests comparing the relative ultimate measurement accuracy computed using the R1-R2 and the R1-computer pairing showed no significant difference on 11 parameters for the 14 parameters analyzed. CONCLUSIONS: The computerized feature parameters may be used as assisted indices for evaluating cervical lymphadenopathies from sonographic images. The semiautomated segmentation method satisfied the accuracy requirement of the feature extraction.

Adolescent↗

Prostate-specific antigen-reactive cytotoxic T lymphocyte precursors in colon cancer patients.

Prostate-specific antigen (PSA) is a representative of the prostate-related antigens, and has been considered to be a tumor marker of prostate cancer. However, some studies suggest that PSA could be produced by several types of tumors. In the present study, we attempted to determine whether or not PSA could be a target molecule in specific immunotherapy for patients with colon cancer. Five colon cancer cell lines were examined for their PSA expression at the mRNA and protein levels by RT-PCR and immunocytostaining, respectively. As a result, four cell lines were found to be positive for PSA at both the mRNA and protein levels. We also attempted to determine whether PSA-reactive cytotoxic T lymphocytes (CTLs) could be induced from the peripheral blood mononuclear cells (PBMCs) of HLA-A24+ colon cancer patients by in vitro stimulation with PSA-derived peptides. As a consequence, PSA peptide-specific CTLs could be generated from the PBMCs of male and female colon cancer patients. Their cytotoxicity against HLA-A24+ PSA-expressing colon cancer cells was dependent on HLA class I-restricted and CD8+ T cells. These findings indicate that PSA-reactive CTL precursors are present in the periphery of colon cancer patients, and that PSA could be a target molecule in specific immunotherapy to colon cancer.

Cell Line, Tumor↗

Initial mechanistic studies of antisense targeting in cells.

UNLABELLED: The continued development of antisense targeting will require a better understanding of the mechanism. METHODS: We performed initial studies of the mechanism of intracellular antisense targeting through measurements of in situ transcription, immunofluorescence, reverse transcription polymerase chain reaction (RT-PCR), 32P-labeled uridine-5'-triphosphate (alpha-32P-UTP) incorporation, nuclear accumulations of 99mTc-labeled DNAs, and messenger RNA (mRNA) transcription rate. As reported earlier, an antisense DNA against the mdr1 mRNA coding for P-glycoprotein (Pgp) and its sense DNA control were used in KB-G2 (Pgp++) cells. RESULTS: Definitive evidence for antisense targeting was obtained by in situ transcription showing complementary DNA elongation in cells exposed to antisense DNA, acting therefore as an intracellular PCR primer of mdr1 mRNA, but not in cells exposed to sense DNA. Immunofluorescence staining showed higher accumulations of antisense versus sense DNAs in KB-G2 cells. Transnuclear migration was confirmed by higher accumulations in the nucleus compared with the cytoplasm in cells incubated with 99mTc-labeled antisense DNA. However, the observed specific accumulations of antisense DNAs of about 10(6) per cell over 10 h could not be explained by a feedback mechanism upregulating transcription in cells exposed to antisense DNA as no increase in mRNA levels was detected by both RT-PCR and 32P-UTP in these cells. To explore an alternative hypothesis, a novel approach using 99mTc-labeled antisense DNA as a probe of total mRNA from cells previously saturated with unlabeled antisense DNA was used to estimate the transcription rate. Compared with controls, mdr1 mRNA levels were found to be initially low after saturation and to recover at about 2,000 copies per minute per cell. If persistent, this transcription rate would provide 10(6) mRNAs in 10 h. CONCLUSION: The results of all studies are consistent with antisense as the mechanism of targeting. Though a feedback mechanism leading to upregulation of mRNA transcription is an unlikely explanation for the high specific accumulations, our results may be explained if antisense DNAs are targeting mdr1 mRNAs produced at high transcription rates. If the target is primarily pre-mRNA in the nucleus rather than mature mRNA in the cytoplasm, this would provide as well an explanation for the observed migration of 99mTc-labeled antisense DNA into the nucleus.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

Regenerating optical properties of individual gold nanoparticles in alcoholic solvents without any surfactant.

We compared the optical properties of gold nanoparticles (GNPs) in various solvents with those of strawberry-like composite particles (Au/SiO2) consisting of a silica core and single attached GNPs. The results show that Au/SiO2 without any surfactant could regenerate well optical properties of individual GNPs in alcoholic solvents. By the electrophoretic light-scattering measurements, the high dispersibility of Au/SiO2 composite particles dispersed in alcoholic solvents has been demonstrated. In addition, using Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, we proposed a possible mechanism to qualitatively account for the dispersibility of Au/SiO2 in organic solvents such as alcoholic solvents and cyclohexane, which may provide an opportunity to manipulate optical signals of single nanoparticle in organic solvents.

Alcohols↗

[Screening for Y chromosomal microdeletions in AZF region with modified multiplex PCR].

OBJECTIVE: Screening for Y chromosomal microdeletions in azoospermia factor (AZF) region with modified multiplex PCR. METHODS: 160 cases with spermatogenetic failure were recruited in the experimental group, while 90 cases of donors in controls. According to the laboratory guidelines supported by European Academy of Andrology (EAA) and European Molecular Genetics Quality Network (EMQN), Y chromosomal microdeletions in AZFa, b, c regions were screened with multiplex PCR. The primers of sequence targeted sites (STSs) and conditions of PCR were modified. RESULTS: Using modified multiplex PCR, 14 (8.75%) cases with Y chromosomal microdeletions were found in the experimental group, while no case in controls. There were 12 cases in AZFc, 1 case in AZFa + b + c, 1 case in AZFb + c. According to statistics, the difference between two groups was significant (P <0.001). Reaction products could be clearly separated with agarose gel and finished in 1 h. CONCLUSION: Modified multiplex PCR protocols supported by EAA and EMQN proved to be very accurate, sensitive and quick, which could be put into screening practice for Y chromosomal microdeletions in AZF region.

Adult↗

[Retrospective analysis of unnatural death in one district of Shanghai City from the years 1995 to 2004].

According to the criterion of International Statistical Classification of Diseases and Related Health Problems Revisions, From 1995 to 2004, Data of unnatural death of residents were analyzed. The results showed that the annual rate of unnatural death was from 4.9 per thousand-4.5 per thousand, and females were of higher rate than males (1.03 to 1.36 times). The three leading causes of unnatural death were falling, traffic accident and suicide. Our date indicate that, unnatural death could influence people's health and life quality, much attentions should be put into its controlling, prevention and other related research.

Accidental Falls↗

[Correlation of Ureaplasma urealyticum and Chlamydia trachomatis infections with male sterility: a meta-analysis of randomized control trials].

OBJECTIVE: To evaluate the correlation of Ureaplasma urealyticum (Uu) and Chlamydia trachomatis (Ct) infections with male sterility. METHODS: Data from CBMA and CNKI were searched and studies were made for the correlation of Uu and Ct infections with male sterility by retrieval strategy worked out according to the Collaborative Review Group search strategy. The results were expressed as odds ratio (OR) and 95% confidence intervals (95% CI). The results of 28 clinical controlled trials from 1994 to 2005 were analyzed by software RevMan 4.2. Odds ratio (OR) was applied to the evaluation of the correlation between Uu infection and male sterility. RESULTS: Eighty-eight relative trials were retrieved, of which 28 were included in the Meta-analysis. The combined ORs of Uu and Ct infections to male sterility were OR(Uu): 4.73 (95% CI: 3.77-5.94) and OR(Ct): 4.59 (95% CI: 3.24-6.50). CONCLUSION: Uu and Ct infections are very important risk factors of sterility in Chinese men.

China↗

[Polymorphism of five short tandem repeat loci on chromosome X in Hebei Han population].

OBJECTIVE: To investigate the polymorphism of DXS6801, DXS6809, DXS7423, DXS7424, DXS9902 five loci in Hebei Han population. METHODS: The PCR products were detected by the polyacrylamide gel electrophresis and DNA sequencing analysis. RESULTS: Among 114 irrelative males and 118 irrelative females from Hebei Han population, 31 alleles were found in the 5 loci. One hundred and one haplotypes of the male were detected and the haplotype diversity reached 0.9975. CONCLUSION: The five loci are relatively abundant in polymorphic information for identification and paternity test. And the obtained data of Hebei Han population can be applied to the X-short tandem repeat genetic data bank.

Alleles↗

[Retrospectively analysis of diagnosis and treatment of the orbital neurilemomas].

OBJECTIVE: To evaluate the diagnosis and surgery of orbital neurilemoma. METHODS: Thirty-eight patients with pathologically confirmed orbital neurilemomas were analyzed retrospectively. The age of the patients ranged from 9 years to 69 years. Twenty-three patients were female and fifteen were male. Standardized A/B scan was performed in 37 cases. CT scanning was performed in 38 patients with contrast scanning in 15 patients and MR imaging was performed in 33 patients with contrast scanning in 32 patients. RESULTS: Neurilemoma was generally low to medium reflective or echo in the ultrasound. Of the 38 cases with orbital neurilemomas, location of tumors was superior of the orbit in 17 cases; lateral and inferior in 19 cases and medial in 2 cases. Shape of the tumors was elongate or round-like 26 cases, leaf-like and dumb-bell 12 cases. CT scanning showed soft tissue high density mass in 32 cases, 6 cases were heterogeneity (for cystoid change). MR imaging in 33 patients displayed a identical T1 and a long T2 signal intensity weighted images in 4 cases; identical T1 and T2 mixed signal (short, identical and long signal) in 28 cases; identical T1 and T2 in 1 cases. After Gd-DTPA enhancement in 32 cases, heterogeneity enhancement of the mass was seen in 28 cases, marked enhancement 4 cases. Four cases in all cases was found orbital-cranial communicate mass. Surgical approach was lateral orbitotomy in 26 cases, combined lateral and medial orbitotomy in 2 cases, anterior orbitotomy 4 cases and medial orbitotomy in 2 cases. CONCLUSIONS: Modern medical imaging, especial MR imaging can demonstrate the site, configuration, and characteristics of the tumors and contribute to the diagnosis and treatment. Skill of surgery can improve the rate of success and decrease the complications.

Adolescent↗