Biomedical subjects

Jun Yang

Publications and source records attributed to Jun Yang.

At least 91 records · Page 5Linked to original sources

PubMed2006

Through the central V2, not V1 receptors influencing the endogenous opiate peptide system, arginine vasopressin, not oxytocin in the hypothalamic paraventricular nucleus involves in the antinociception in the rat.

Our previous study has proven that hypothalamic paraventricular nucleus (PVN) played a role in the antinociception. The central bioactive substances involving in the PVN regulating antinociception were investigated in the rat. The results showed that electrical stimulation of the PVN increased the pain threshold, and L-glutamate sodium injection into the PVN elevated the pain threshold, but the PVN cauterization decreased the pain threshold; pain stimulation raised the arginine vasopressin (AVP), not oxytocin (OXT), leucine-enkephalin (L-Ek), beta-endorphin (beta-Ep) and DynorphinA1-13 (DynA1-13) concentrations in the PVN tissue using micropunch method, heightened AVP, L-Ek, beta-Ep and DynA1-13, not OXT concentrations in the PVN perfuse liquid, and reduced the number of AVP-, not OXT, L-Ek, beta-Ep and DynA1-13-immunoreactive neurons in the PVN especially in the posterior magnocellular part of the PVN using immunocytochemistry. There was a negative relationship between the PVN AVP concentration and the pain threshold; pain stimulation enhanced the AVP, not OXT mRNA expression in the PVN using in situ hybridization and RT-PCR; intraventricular injection of anti-AVP serum completely reversed L-glutamate sodium injection into the PVN-induced antinociception, and administration of naloxone - the opiate peptide antagonist, partly blocked this L-glutamate sodium effect, but anti-OXT serum pretreatment did not influence this L-glutamate sodium effect; L-glutamate sodium injection into the PVN-induced analgesia was inhibited by V2 receptor antagonist - d(CH2)5[D-Ile2, Ile4, Ala-NH2(9)]AVP, not V1 receptor antagonist - d(CH2)5Tyr(Me)AVP. The data suggested that the PVN was limited to the central AVP, not OXT, which was through V2, not V1 receptors influencing the endogenous opiate peptide system, to regulate antinociception.

Analysis of Variance↗

PubMed2006

Selective diethylzinc reduction of imines in the presence of ketones catalyzed by Ni(acac)2.

A selective reduction method of an electronically deficient imine in the presence of ketone was developed by employing Et(2)Zn and 5 mol % of Ni(acac)(2). The method was applied in the reduction of S(S)-tert-butanesulfinyl ketimines 1 to afford amines 2 in 23-92% yields and 73:27 to 98:2 diastereoselectivities. A plausible mechanism was proposed on the basis of an NMR study.

Journal Article↗

PubMed2006

Generalized eikonal treatment of the Gouy phase shift.

We use a generalized refractive index that includes diffraction effects to show that the Gouy phase shift can be seen as an intensity averaged optical path difference between the generalized eikonal and the geometrical eikonal. This approach generalizes previous treatments to include the effects of phase distortion and confirms the role of transverse spatial confinement in the Gouy shift.

Journal Article↗

PubMed2006

Novel insights into the mechanism of action of FTY720 in a transgenic model of allograft rejection: implications for therapy of chronic rejection.

FTY720 is a high-affinity agonist at the sphingosine 1-phosphate receptor 1 that prevents lymphocyte egress from lymphoid tissue and prolongs allograft survival in several animal models of solid organ transplantation. In this study we used a recently developed adoptive transfer model of TCR transgenic T cells to track allospecific CD4+ T cell expansion and trafficking characteristics, cytokine secretion profiles, and surface phenotype in vivo in the setting of FTY720 administration. We report that FTY720 administration had no effect on alloantigen-driven T cell activation, proliferation, acquisition of effector-memory function, or T cell apoptosis. However, FTY720 caused a reversible sequestration of alloantigen-specific effector-memory T cells in regional lymphoid tissue associated with a decrease in T cell infiltration within the allograft and a subsequent prolongation in allograft survival. Furthermore, delayed administration of FTY720 in a cardiac model of chronic allograft rejection attenuated the progression of vasculopathy and tissue fibrosis consistent with the hypothesis that FTY720 interrupts the trafficking of activated effector-memory T cells. These data have important implications for targeting the sphingosine 1-phosphate receptor 1 in solid organ transplantation.

Adoptive Transfer↗

PubMed2006

Influence of local and systemic CTLA4Ig gene transfer on corneal allograft survival.

BACKGROUND: To analyse the effects of local (ex vivo) or systemic (in vivo) administration of adenovirus type 5 encoding CTLA4Ig (AdCTLA4Ig) on its influence to prolong corneal allograft survival and to study the underlying mechanisms. METHODS: A MHC class I/II mismatched rat corneal transplant model was used. Recipients were randomly assigned to receive ex vivo gene-modified corneas expressing either CTLA4Ig, CTLA4Ig/IL-10 or a single intraperitoneal (i.p.) injection (1.0 x 10(9) or 1.0 x 10(10) infectious particles) of AdCTLA4Ig 1 day before transplantation and graft survival was analysed. The immunoregulatory effect of this treatment was examined by analysing intra-graft cytokine mRNA expression pattern at day 12 post-transplant. The anti-adenovirus immunity also was investigated. RESULTS: Ex vivo gene transfer resulted in a modest but significant prolongation of graft survival (p = 0.0036 compared to no treatment). In contrast, systemic gene therapy (1.0 x 10(9) or 1.0 x 10(10) infectious particles) significantly prolonged graft survival (p = 0.0007 and 0.0001, respectively, compared to no treatment). Systemic (1.0 x 10(10) infectious particles) therapy resulted in frequent indefinite survival of allogeneic grafts which was not observed in the other therapeutic regimens. Moreover, systemic therapy prevented the intra-graft accumulation and activation of T cells and resulted in a reduced mRNA expression of both TH1 and TH2 cytokines. The generation of anti-adenovirus antibodies was also efficiently inhibited. CONCLUSIONS: CTLA4Ig gene therapy is a successful strategy for the prevention of allogeneic graft rejection in corneal transplantation. Our work has further elucidated the mechanisms of corneal allograft rejection which may lead to novel therapeutic strategies.

Abatacept↗

PubMed2006

Urinary profiling investigation of metabolites with cis-diol structure from cancer patients based on UPLC-MS and HPLC-MS as well as multivariate statistical analysis.

Nucleosides are an important class of metabolites and have been investigated as potential tumor biomarkers. A method based on ultra peerformance liquid chromatography (UPLC)-TOF MS was developed to analyze urinary nucleosides and other metabolites with cis-diol structure to distinguish between cancer patients and healthy persons and compare the results with those obtained by HPLC. The data showed that the UPLC method used about one third of the time required by HPLC and achieved a much better chromatographic resolution and increased sensitivity, the number of peaks detected by UV being 79 and 94 for HPLC and UPLC, respectively. With UPLC-TOF MS, more information was obtained about metabolites, the separation of cancer patients from healthy persons was significantly improved, and more potential biomarkers were found. The method based on UPLC-TOF MS is a powerful technique for the study of metabolite profiles.

Adult↗

PubMed2006

Optical and electrochemical detection techniques for cell-based microfluidic systems.

The ability to fabricate microfluidic systems with complex structures and with compatible dimensions between the microfluidics and biological cells have attracted significant attention in the development of microchips for analyzing the biophysical and biochemical functions of cells. Just as cell-based microfluidics have become a versatile tool for biosensing, diagnostics, drug screening and biological research, detector modules for cell-based microfluidics have also undergone major development over the past decade. This review focuses on detection methods commonly used in cell-based microfluidic systems, and provides a general survey and an in-depth look at recent developments in optical and electrochemical detection methods for microfluidic applications for biological systems, particularly cell analysis. Selected examples are used to illustrate applications of these detection systems and their advantages and weaknesses.

Biosensing Techniques↗

PubMed2006

PASA--a program for automated protein NMR backbone signal assignment by pattern-filtering approach.

We present a new program, PASA (Program for Automated Sequential Assignment), for assigning protein backbone resonances based on multidimensional heteronuclear NMR data. Distinct from existing programs, PASA emphasizes a per-residue-based pattern-filtering approach during the initial stage of the automated 13Calpha and/or 13Cbeta chemical shift matching. The pattern filter employs one or multiple constraints such as 13Calpha/Cbeta chemical shift ranges for different amino acid types and side-chain spin systems, which helps to rule out, in a stepwise fashion, improbable assignments as resulted from resonance degeneracy or missing signals. Such stepwise filtering approach substantially minimizes early false linkage problems that often propagate, amplify, and ultimately cause complication or combinatorial explosion of the automation process. Our program (http://www.lerner.ccf.org/moleccard/qin/) was tested on four representative small-large sized proteins with various degrees of resonance degeneracy and missing signals, and we show that PASA achieved the assignments efficiently and rapidly that are fully consistent with those obtained by laborious manual protocols. The results demonstrate that PASA may be a valuable tool for NMR-based structural analyses, genomics, and proteomics.

Algorithms↗

PubMed2006

Support vector machine-based feature selection for classification of liver fibrosis grade in chronic hepatitis C.

Although liver biopsy is currently regarded as the gold standard for staging liver fibrosis in chronic hepatitis C, it is a costly invasive procedure and carries a small risk for complication. Our aim in this study was to construct a simple model to distinguish between patients with no or mild fibrosis (METAVIR F0-F1) versus those with clinically significant fibrosis (METAVIR F2-F4). We retrospectively studied 204 consecutive CHC patients. Thirty-four serum markers with age, gender, duration of infection were assessed to classify fibrosis with a classifier known as the support vector machine (SVM). The method of feature selection known as sequential forward floating selection (SFFS) was introduced before the performance of SVM. When four serum markers were extracted with SFFS-SVM, F2-F4 could be predicted accurately in 96%. Our study showed that application of this model could identify CHC patients with clinically significant fibrosis with a high degree of accuracy and may decrease the need for liver biopsy.

Adult↗

PubMed2006

Health effects in children aged 3-6 years induced by environmental lead exposure.

OBJECTIVES: To investigate the involvement of oxidative damage in lead-induced toxicity in children aged 3-6 years and to enlighten whether oxidative stress indicators are correlated with the known indices of lead toxicity. METHODS: Blood samples were collected from 408 subjects (217 boys and 191 girls) in the urban kindergartens. The age range of the subjects was 3-6 years. Blood lead levels (BLLs) were analyzed by flameless atomic absorption spectrophotometry. Activities of delta-aminolevulinic acid dehydratase (ALAD), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and contents of glutathione (GSH) in erythrocyte and levels of plasma malondialdehyde (MDA) were analyzed spectrophotometrically in these children. RESULTS: Children with BLLs >or = 100 microg/L had significantly decreased erythrocyte ALAD activities and increased plasma MDA levels compared to the children with BLLs < 100 microg/L. No significant changes were observed in erythrocyte SOD and GSH-Px activities and GSH levels associated with elevated BLLs in these children. CONCLUSION: Present data indicate that oxidative damage could be induced by lead in children with BLLs > or = 100 microg/L, and this may partly be attributed to the inhibited ALAD activities. Statistically significant changes of oxidative stress parameters in preschool children while BLLs were more than 100 microg/L could be implicated that oxidative damage might contribute to lead-induced intellectual impairment.

Child↗

PubMed2006

High prevalence of aeroallergen sensitization among infants of atopic parents.

OBJECTIVE: To present methodology to identify atopic parents and determine the prevalence of sensitization to 15 aeroallergens in their infant offspring. STUDY DESIGN: A birth cohort of infants was identified from birth records; an infant was enrolled if 1 of the parents reported allergy respiratory symptoms and had a positive skin prick test (SPT) to a common aeroallergen. At age 1 year, these infants were tested to the same aeroallergens. RESULTS: Of the 680 enrolled infants, 28.4% were SPT+ to 1 or more aeroallergens and/or food, and 18.0% were positive to 1 or more aeroallergens. By category of allergens, 9.7% were sensitized to pollens, 7.5% to molds, 4.3% to house dust mite and/or cockroach, and 3.4% to dog and/or cat. Of the infants who were positive to an aeroallergen, 65.7% remained positive at age 2 years. CONCLUSIONS: Infants born to atopic parents with percutaneous sensitization to aeroallergens are at increased risk for aeroallergen sensitization during infancy, which persists to age 2 years. These findings suggest that current clinical practices, which generally avoid skin testing before age 2 years, be reassessed in this population of high-risk children.

Allergens↗

PubMed2006

Predicting the nuclear localization signals of 107 types of HPV L1 proteins by bioinformatic analysis.

In this study, 107 types of human papillomavirus (HPV) L1 protein sequences were obtained from available databases, and the nuclear localization signals (NLSs) of these HPV L1 proteins were analyzed and predicted by bioinformatic analysis. Out of the 107 types, the NLSs of 39 types were predicted by PredictNLS software (35 types of bipartite NLSs and 4 types of monopartite NLSs). The NLSs of the remaining HPV types were predicted according to the characteristics and the homology of the already predicted NLSs as well as the general rule of NLSs. According to the result, the NLSs of 107 types of HPV L1 proteins were classified into 15 categories. The different types of HPV L1 proteins in the same NLS category could share the similar or the same nucleocytoplasmic transport pathway. They might be used as the same target to prevent and treat different types of HPV infection. The results also showed that bioinformatic technology could be used to analyze and predict NLSs of proteins.

Amino Acid Sequence↗

PubMed2006

High performance liquid chromatography-mass spectrometry for metabonomics: potential biomarkers for acute deterioration of liver function in chronic hepatitis B.

Metabonomics methods have been successfully applied to the drug discovery, toxicology, phytochemistry, and clinical fields. Here, we report a self-developed metabonomics platform which is based on high performance liquid chromatography-mass spectrometry (HPLC-MS) technique and applied to the investigation of acute deterioration of liver function in chronic hepatitis B to find the potential biomarkers. Sera from 50 healthy persons and 37 patients with acute deterioration of liver function in chronic hepatitis B were analyzed by HPLC-MS after removal of proteins. After de-noise, peak detection and peak alignment, the data of metabolites were fed to partial least squares discriminant analysis (PLS-DA) to find the potential biomarkers. According to the corresponding tandem mass results, several potential biomarkers were identified: Lysophosphatidyl Choline (LPC) C18:0, LPC C16:0, LPC C18:1, LPC C18:2, and glycochenodeoxycholic acid (GCDCA) (or its isomer glycodeoxycholic acid (GDCA)). On the basis of the relevant literature and pathway databases, the biological significance of the present study is discussed.

Adult↗

PubMed2006

Neuronal affinity of a C7C loop peptide identified through phage display.

Phage display is a promising tool for the screening of peptides with high affinity for specific cells. Here we describe a novel peptide with neuronal affinity isolated from a C7C library. We designed a two-tiered biopanning strategy initially selecting for ganglioside binding and subsequently selecting for binding to PC12 cells. At the completion of biopanning, 54.8% of phage clones bore the identical peptide (Tet.C7C.1). Immunofluorescence confirmed selective binding of this clone to differentiated PC12 cells. Tet.C7C.1 was synthesized and fluorescein conjugated. The synthetic peptide binds neuronal cell lines (SH-SY5Y, NSC-34 and PC12 cells) and tissue (DRG and spinal cord). The C7C structure creates a loop that minimizes the impact of peptide insertion on the confirmation of the recipient protein. Small loop peptides have the ideal characteristics for modification of viral vector capsids without undermining genome packaging. The neuronal binding properties of this peptide may be applied in the development of neurotropic viral vectors.

Amino Acid Sequence↗

PubMed2006

Hepatic histologic response (HR) to combination therapy among HCV/HIV-coinfected individuals: interferon induces HR independent of sustained virologic response (SVR).

Most HIV/HCV-coinfected patients fail to achieve a sustained virologic response (SVR) to peginterferon-ribavirin therapy. We examined the hepatic histologic response (HR), defined as an improvement in hepatic inflammation scores of two points or more, to combination therapy among HIV/HCV-coinfected subjects. An open label prospective trial treated 32 HIV/HCV-coinfected patients with peginterferon alpha-2b and ribavirin for 48 weeks. Liver biopsies, scored by a single pathologist using the Histology Activity Index (HAI, range 0-18) and Ishak fibrosis scores (range 0-6), were performed before and after treatment. Gene expression profiles of PBMCs were performed using Affymetrix U133A gene chips. A total of 87% of SVR subjects and 88% of nonresponders (NR) had an HR, but no significant change in the liver fibrosis scores was observed (p > 0.05). For genotype 1 patients, a baseline fibrosis score </=2 was related to a higher likelihood of SVR than those with a score >2 (p = 0.012). Combination therapy for HCV among HIV-coinfected subjects resulted in a modest SVR rate. Persons with mild liver disease had a better SVR rate, suggesting early treatment may be beneficial. Combination therapy resulted in an HR for most of the patients, however, further follow-up of these patients will determine the durability of such an HR.

Antiviral Agents↗

PubMed2006

Effects of tetrandrine on cytosolic free calcium concentration in corpus cavernosum smooth muscle cells of rabbits.

AIM: To study the relaxation mechanisms of tetrandrine (Tet) on the corpus cavernosum smooth muscle. METHODS: The corpus cavernosum smooth muscle cells from New Zealand white rabbits were cultured in vitro. [Ca(2+)](i) was measured by Fluorescence Ion Digital Imaging System, using Fluo-2/AM as a Ca(2+)-sensitive fluorescent indicator. RESULTS: Tet (1, 10 and 100 micromol/L) had no effect on the resting [Ca(2+)](i) (P>0.05). In the presence of extracellular Ca(2+) (2.5 mmol/L), Tet (1, 10 and 100 micromol/L) inhibited [Ca(2+)](i) elevation induced by high K(+) and phenylephrine (PE) in a concentration-dependent manner (P>0.05). In calcium free solution containing egtaic acid, Tet (1 and 10 micromol/L) had no inhibitory effects on [Ca(2+)](i) elevation induced by PE (P>0.05). However, Tet (100 micromol/L) inhibited [Ca(2+)](i) elevation induced by PE (P>0.05). CONCLUSION: Tet inhibited the Ca(2+) influx from the extracellular site via voltage-activated Ca(2+) channel and alpha(2)-adrenoceptor-operated Ca(2+) channel. At a high concentration, Tet might inhibit the cytosolic calcium pool release in cultured corpus cavernosum smooth muscle cells. This inhibitory action on [Ca(2+)](i) might be one of the relaxation mechanisms of Tet on the corpus cavernosum smooth muscle.

Alkaloids↗

PubMed2006

Functional genomics of innate host defense molecules in normal human monocytes in response to Aspergillus fumigatus.

Aspergillus fumigatus induces the release of innate immune-related molecules from phagocytic cells early in the course of infection. Little is known, however, about the complex expression profiles of the multiple genes involved in this response. We therefore investigated the kinetics of early gene expression in human monocytes (HMCs) infected with conidia of A. fumigatus using DNA microarray analysis. Total RNA from HMCs at 0, 2, 4, and 6 h was extracted, linearly amplified, hybridized onto Affymetrix HG133 Plus 2.0 gene chips, and analyzed with an Affymetrix scanner. Changes in gene expression were calculated as a ratio of those expressed by infected versus control HMCs. Aspergillus fumigatus induced differential regulation of expression in 1,827 genes (P < 0.05). Genes encoding cytokines and chemokines involved in host defense against A. fumigatus, including interleukin-1beta (IL-1beta), IL-8, CXCL2, CCL4, CCL3, and CCL20, as well as the opsonin long pentraxin 3, were up-regulated during the first 2 to 6 h, coinciding with an increase in phagocytosis. Simultaneously, genes encoding CD14, ficolin1, and MARCO were down-regulated, and genes encoding IL-10 and matrix metalloproteinase 1 were up-regulated. Up-regulation of the genes encoding heat shock proteins 40 and 110 and connexins 26 and 30 may point to novel molecules whose role in the pathogenesis of aspergillosis has not been previously reported. Verification of the transcriptional profiling was obtained for selected genes by reverse transcription-PCR and enzyme immunoassay. Thus, A. fumigatus conidia induced a coordinated expression of genes important in host defense and immunomodulation.

Aspergillosis↗

PubMed2006

Novel cross talk of Kruppel-like factor 4 and beta-catenin regulates normal intestinal homeostasis and tumor repression.

Epithelial cells of the intestinal mucosa undergo a continual process of proliferation, differentiation, and apoptosis which is regulated by multiple signaling pathways. The Wnt/beta-catenin pathway plays a critical role in this process. Mutations in the Wnt pathway, however, are associated with colorectal cancers. Krüppel-like factor 4 (KLF4) is an epithelial transcriptional factor that is down-regulated in many colorectal cancers. Here, we show that KLF4 interacts with beta-catenin and represses beta-catenin-mediated gene expression. Moreover, KLF4 inhibits the axis formation of Xenopus embryos and inhibits xenograft tumor growth in athymic nude mice. Our findings suggest that the cross talk of KLF4 and beta-catenin plays a critical role in homeostasis of the normal intestine as well as in tumorigenesis of colorectal cancers.

Adenomatous Polyposis Coli Protein↗