PubMed Health⌕ Search

Biomedical subjects

Xin Feng

Publications and source records attributed to Xin Feng.

At least 19 recordsLinked to original sources
PubMed2024

Core planar cell polarity genes VANGL1 and VANGL2 in predisposition to congenital vertebral malformations.

Congenital scoliosis (CS), affecting approximately 0.5 to 1 in 1,000 live births, is commonly caused by congenital vertebral malformations (CVMs) arising from aberrant somitogenesis or somite differentiation. While Wnt/ß-catenin signaling has been implicated in somite development, the function of Wnt/planar cell polarity (Wnt/PCP) signaling in this process remains unclear. Here, we investigated the role of Vangl1 and Vangl2 in vertebral development and found that their deletion causes vertebral anomalies resembling human CVMs. Analysis of exome sequencing data from multiethnic CS patients revealed a number of rare and deleterious variants in VANGL1 and VANGL2, many of which exhibited loss-of-function and dominant-negative effects. Zebrafish models confirmed the pathogenicity of these variants. Furthermore, we found that Vangl1 knock-in (p.R258H) mice exhibited vertebral malformations in a Vangl gene dose- and environment-dependent manner. Our findings highlight critical roles for PCP signaling in vertebral development and predisposition to CVMs in CS patients, providing insights into the molecular mechanisms underlying this disorder.

Animals↗
PubMed2006

The PANE1 gene encodes a novel human minor histocompatibility antigen that is selectively expressed in B-lymphoid cells and B-CLL.

Minor histocompatibility antigens (mHAg's) are peptides encoded by polymorphic genes that are presented by major histocompatibility complex (MHC) molecules and recognized by T cells in recipients of allogeneic hematopoietic cell transplants. Here we report that an alternative transcript of the proliferation-associated nuclear element 1 (PANE1) gene encodes a novel human leukocyte antigen (HLA)-A(*)0301-restricted mHAg that is selectively expressed in B-lymphoid cells. The antigenic peptide is entirely encoded within a unique exon not present in other PANE1 transcripts. Sequencing of PANE1 alleles in mHAg-positive and mHAg-negative cells demonstrates that differential T-cell recognition is due to a single nucleotide polymorphism within the variant exon that replaces an arginine codon with a translation termination codon. The PANE1 transcript that encodes the mHAg is expressed at high levels in resting CD19(+) B cells and B-lineage chronic lymphocytic leukemia (B-CLL) cells, and at significantly lower levels in activated B cells. Activation of B-CLL cells through CD40 ligand (CD40L) stimulation decreases expression of the mHAg-encoding PANE1 transcript and reciprocally increases expression of PANE1 transcripts lacking the mHAg-encoding exon. These studies suggest distinct roles for different PANE1 isoforms in resting compared with activated CD19(+) cells, and identify PANE1 as a potential therapeutic target in B-CLL.

Alternative Splicing↗
PubMed2005

Stem cell therapy in the aging hearts of Fisher 344 rats: synergistic effects on myogenesis and angiogenesis.

OBJECTIVE: Advanced age is a major risk factor for ventricular dysfunction and reduction of cardiac reserve. Finding novel approaches to prevent and attenuate heart dysfunction associated with advanced age is a major therapeutic challenge. The present study was designed to test whether engrafted embryonic stem cells could improve myocardial function in aging hearts. METHODS: Cultured mouse embryonic stem cells used for cell therapy were transfected with green fluorescent protein. Aging rats in the cell-treated group received intramyocardial injection of embryonic stem cells. Hemodynamic measurement, myocyte counting, and evaluation of blood flow were performed 6 weeks after cell transplantation. RESULTS: Embryonic stem cell therapy partially improved cardiac reserve, as reflected by the in vivo response to isoproterenol (INN: isoprenaline) stimulation in aging hearts 6 weeks after cell implantation. The functional benefits from engrafted embryonic stem cells were associated with increased myocyte numbers and enhanced left ventricular blood perfusion in the aging heart. The characteristic phenotype of engrafted embryonic stem cells was identified in the transplanted heart on the basis of green fluorescent protein-positive spots that were further demonstrated to differentiate into cardiac tissue with positive staining for cardiac alpha-myosin heavy chain. CONCLUSIONS: Regenerating cardiomyocytes and increasing regional blood perfusion in the aging heart after embryonic stem cell transplantation synergistically resulted in improvement of cardiac function. Embryonic stem cell transplantation might hold significant clinical potential in attenuating the progressive decrease of cardiac function associated with advanced aging.

Aging↗
PubMed2005

Effects of Cu/Zn superoxide dismutase on strain injury-induced oxidative damage to skeletal muscle in rats.

This study was designed to determine whether the supplement of superoxide dismutase (SOD) could attenuate strain-induced oxidative damage to skeletal muscle in rats. Experimental animals were injured in right gastrocnemius muscles by a strain injury model. SOD-treated groups were given Cu/Zn SOD 10 000 U/kg body weight per day since injured, while control groups were given normal saline. Parameters of antioxidant and muscle damage were detected in plasma 3 and 7 days postinjury. The injured muscles were removed and fixed for histology observation and immunohisto-chemistry assay of desmin. The results showed that plasma levels of SOD, glutathione peroxidase (GSH-Px), total antioxidant capacity (T-AOC) in SOD group were significantly higher than in the saline group on day 3 or 7, while the plasma creatine kinase (CK) and malondialdehyde (MDA) were lower in the SOD group than in the saline group. The histological examination of muscle sections revealed a lower degree of damage in the SOD group in which the expression level of desmin was higher than in the saline group. It is suggested that SOD supplement may attenuate strain-induced muscle damage and facilitate its regeneration.

Animals↗
PubMed2004

IL-12 receptor-mediated upregulation of FasL in human ovarian carcinoma cells.

The expression and functions of IL-12 receptor (IL-12R) in human ovarian carcinoma cell lines have been investigated. Ovarian carcinoma cells express both the IL-12Rbeta1 and the IL-12Rbeta2 subunits. IL-12R crosslinking resulted in phosphorylation of Tyk2, p44 (ERK1) and Akt kinases and activation of STATs 2, 3, 4 and 5. IL-12 induced substantial upregulation of Fas ligand (FasL) surface expression in ovarian carcinoma cells paralleled by an increased ability to induce apoptosis in Jurkat cells and PHA-activated lymphocytes. The induction of surface expression of FasL by IL-12 was not due to upregulation of FasL gene expression, but resulted from downregulation of matrix metalloproteinases (MMPs)-3 and -7 and consequently reduced cleavage of FasL from the cell surface. These findings bring new insights into the significance of IL-12-mediated effects in nonlymphoid cancer cells that might be of importance for improving the design of IL-12-based therapies for ovarian cancer.

Angiogenesis Inhibitors↗
PubMed2004

Low temperature induced synthesis of TiN nanocrystals.

TiN nanocrystals were successfully prepared through the direct reaction between TiCl(4) and NaNH(2) induced at 300 degrees C. The yield based on Ti is approximately 80%. X-ray powder diffraction indicated that the product was cubic TiN with a lattice constant of a = 4.243 A. Transmission electron microscopy revealed that nanocrystalline TiN with a diameter of 10 nm or so and extremely long straight rods were synthesized. The possible formation mechanism was also proposed.

Journal Article↗
PubMed2004

Highly efficient liquid-phase photooxidation of an azo dye methyl orange over novel nanostructured porous titanate-based fiber of self-supported radially aligned H2Ti8O17 x 1.5H2O nanorods.

Novel nanostructured porous fibers of self-supported, radially aligned H2Ti8O17 x 1.5H2O nanorods were prepared from layered H2Ti4O9 x 1.2H2O tetratitanate fibers by novel solvothermal reaction in glycerine at 150-250 degrees C. The H2Ti8O17 x 1.5H2O fibers with diameters of 0.5-1.5 microm and lengths of 10-20 microm consist of multi-scale nanopores and nanostructures. They also are of high crystallinity, large surface area of 127 m2 g(-1), and stable phase up to 350 degrees C. Photocatalytic activity of the H2Ti8O17 x 1.5H2O fibers was evaluated in aqueous photooxidation of an azo dye methyl orange in the presence of UV irradiation and 02, using P-25 as the standard sample. Both the photocatalytic activity and the dispersity-agglomeration property of H2Ti8O17 x 1.5H2O fibers are pH-controllable. Highly photooxidative activity, superior to that of P-25, occurs at pH 6.0-11.0 due to certain distinguishable material characteristics and to large amounts of adsorbed reactants of surface active OH* free radicals, surface hydroxyl OH, O2*-, O*OH, and methyl orange. The agglomeration of H2Ti8O17 x 1.5H2O fibers becomes more serious from pH 2.0 to pH 5.0 and from pH 6.0 to pH 11.0. Well-dispersed H2Ti8O17 x 1.5H2O fibers occur at pH 6.0. Both the total photodegradation of waste chemicals and the entire sedimentation of H2Ti8O17 x 1.5H2O fibers can be timed to end simultaneously at suitable pH value. The photocatalyst-free reaction solution is then easily removed, and the fresh wastewater is added again. Standard unit operation processes of chemical engineering are used to design a continuous, low-cost, large-scale, liquid-phase photocatalysis technique based on the H2Ti8O17 x 1.5H2O fibers.

Azo Compounds↗
PubMed2004

Virological and immunological outcomes in HIV-1-infected Chinese patients treated with a combination of Efavirenz and Indinavir for 48 weeks.

BACKGROUND: The incidence of HIV-1-related infection diseases and the mortality of AIDS have dramatically decreased since highly active antiretroviral therapy began to be used clinically in China in 1999. And we initiated a second clinical trial using a combination of Efavirenz and Indinavir to observe the effects of the immunoreaction. METHODS: Twenty patients with laboratory-confirmed chronic HIV-1 infection were recruited. Blood samples were collected initially and during the weeks after initiation of treatment. Within 48 hours of blood sampling, peripheral blood plasma and mononuclear cells were separated using routine methods. HIV-1 viral load was measured in thawed plasma samples. Within 48 hours of peripheral blood sampling, CD4(+) and CD8(+) T cell subsets were enumerated. RESULTS: The drug regimen was efficient in reducing HIV-1 plasma viral load and increasing total CD4(+) T cell counts. The percentage of CD4(+) and CD8(+) T cell subsets expressing CD38 and HLA-DR activation markers was positively correlated with plasma viral load and tended to normalize. CONCLUSIONS: The combination of Efavirenz and Indinavir was generally well tolerated and efficient at reducing HIV-1 RNA. Furthermore, the treatment improved the immunological function.

ADP-ribosyl Cyclase↗
PubMed2004

[Inhibitory effects of basic fibroblast growth factor on fibrosis of strain injured skeletal muscles in rats].

OBJECTIVE: To investigate the effects of exogenous basic fibroblast growth factor (bFGF) on the healing of strain injured skeletal muscles in rats. METHODS: Eighteen male SD rats were randomly divided into three groups: no strain control group (C(on)), muscle strained and bFGF treated group (S(b)), or normal saline treated group (S(0)). The gastrocnemius of rats in the S(b) and S(0) groups was strained and the animals were treated with bFGF (200 AU/d) or normal saline for six days. Vimentin expression, an indicator of muscle fibrosis in injured muscles (expressed as integral optical density, IOD), was measured by immunohistochemistry. RESULTS: The IOD of vimentin in the S(0) group [(24.29 +/- 7.91) x 10(3)] was higher than that in the C(on) group [(5.75 +/- 3.87) x 10(3)] (P < 0.01). The IOD of vimentin in bFGF treated group [(15.78 +/- 7.72) x 10(3)] was lower than that in the normal saline treated group (P < 0.01). CONCLUSION: The exogenous bFGF may facilitate the repair of muscle structure and function by reducing vimentin expression and fibrosis in strain injured muscles.

Animals↗
PubMed2004

[Dynamics of peripheral blood lymphocytes and their subpopulations in patients with severe acute respiratory syndrome].

OBJECTIVE: To study on the dynamics of peripheral blood lymphocytes and their subpopulations in patients with severe acute respiratory syndrome. METHODS: Using flow cytometry, the absolute numbers of peripheral blood lymphocytes and their subpopulations in 240 SARS patients (696 specimens) and 51 individuals as controls, were counted and compared. RESULTS: The absolute numbers of peripheral blood lymphocytes and their subpopulations (CD45, CD3, CD4, CD8) were 1298 +/- 785, 897 +/- 606, 510 +/- 372, 362 +/- 263/mm(3), respectively, significantly lower in SARS patients as compared to the normal controls (2024 +/- 423, 1391 +/- 289, 795 +/- 129, 551 +/- 183/mm(3)). Of SARS patients, severe group (1095 +/- 740, 740 +/- 562, 419 +/- 346, 304 +/- 244/mm(3)) had lower counts than that of mild group (1404 +/- 788, 991 +/- 612, 564 +/- 378, 396 +/- 267/mm(3)), and in group with deaths (587 +/- 493, 369 +/- 371, 204 +/- 191, 150 +/- 130/mm(3)) was lower than that of recovery group (1355 +/- 776, 948 +/- 603, 539 +/- 375, 382 +/- 263/mm(3)). There were significant differences (P < 0.01) for CD45, CD3, CD4, CD8, but with no significant difference (P > 0.05) for CD4/CD8 ratio between severe and mild, recovery and death groups. The lymphocytes and their subpopulations (CD45, CD3, CD4, CD8) declined in the 1st week and to the lowest level (977 +/- 579, 641 +/- 466, 360 +/- 275, 270 +/- 216/mm(3)) in the 2nd week. Then the lymphocytes and their subpopulations gradually increased during the recovery of the disease. CONCLUSION: The absolute numbers of peripheral blood lymphocytes and their subpopulations in SARS patients might be used as one of the methods for diagnosis on the severity and prognosis of the disease.

Adult↗
PubMed2004

Effects of estrogen on gastrocnemius muscle strain injury and regeneration in female rats.

AIM: To study the effects of estrogen on muscle damage and regeneration after acute passive gastrocnemius muscle strain injury in female Sprague-Dawley rats. METHODS: Rats were divided into 5 groups: ovariectomized, strained and treated with low-dosage estradiol (20 microg/d) (E(low)), treated with high-dosage estradiol (200 microg/d) (E(high)), treated with oil placebo (Oil), strained with no ovariectomy (Strain), and sham operated with no strain and no ovariectomy (Con). Muscle damage index [plasma creatine kinase (CK)], antioxidant indexes [glutathione (GSH), Vitamin E (Vit E), total antioxidant capability (TAC)], and muscle regeneration index (desmin) were investigated at 7 d. RESULTS: The plasma CK activity increased but GSH, Vit E, and TAC levels decreased after muscle strain injury (Strain vs Con P<0.05). Plasma CK activity was the greatest while GSH, Vit E, and TAC were the lowest in the Oil group among the five groups (P<0.01). Plasma CK in the E(high) and Strain groups was lower than that in the E(low) group. Plasma GSH, Vit E, and TAC were higher in the E(high) and Strain groups compared with the E(low) group (P<0.05). The expression of desmin in the E(high) and Strain groups was higher than that in the E(low) group (P<0.01) while that in the Oil group was the lowest in all the five groups (P<0.01). CONCLUSION: Endogenous estrogen in normal female rats or exogenous estrogen in ovariectomized rats could improve antioxidant capability in vivo, so that reduced muscle damage and accelerated muscle regeneration post gastronemius muscle strain injury.

Animals↗
PubMed2003

Dantrolene: effects on abnormal intracellular Ca(2+) handling and inotropy in postinfarcted rat myocardium.

The present study was designed to investigate the effects of dantrolene on intracellular Ca(2+) ([Ca(2+)](i)) handling and inotropy in rat infarcted myocardium. Dantrolene-treated rats with myocardial infarction were placed into two different dosage groups. The infarcted control group received placebo only. Isometric contractility and intracellular Ca(2+) transients were recorded simultaneously in isolated papillary muscles. Diastolic [Ca(2+)](i) was significantly lower in muscle preparations from infarcted rats receiving dantrolene compared to the placebo control group. Additionally, treatment with dantrolene in infarcted rats significantly improved the inotropic response to 10(-4) M isoproterenol. The protein levels of the sarcoplasmic reticulum Ca(2+) ATPase were increased in infarcted rat hearts with dantrolene treatment. We conclude that dantrolene improved the inotropic response to beta-adrenoceptor stimulation in rat postinfarcted myocardium, which is related to improved intracellular Ca(2+) handling, and lowered diastolic Ca(2+) concentration.

Animals↗
PubMed2003

Multiple approaches to data-mining of proteomic data based on statistical and pattern classification methods.

The data-mining challenge presented is composed of two fundamental problems. Problem one is the separation of forty-one subjects into two classifications based on the data produced by the mass spectrometry of protein samples from each subject. Problem two is to find the specific differences between protein expression data of two sets of subjects. In each problem, one group of subjects has a disease, while the other group is nondiseased. Each problem was approached with the intent to introduce a new and potentially useful tool to analyze protein expression from mass spectrometry data. A variety of methodologies, both conventional and nonconventional were used in the analysis of these problems. The results presented show both overlap and discrepancies. What is important is the breadth of the techniques and the future direction this analysis will create.

Artificial Intelligence↗
PubMed2003

Nitric oxide induced ectopic firing in a lumbar nerve root with cauda equina compression.

Nitric oxide is thought to be involved in the pathophysiology of radiculopathy attributable to herniated intervertebral disc, but its effect on ectopic firing, which is the main source of sciatica, has not been investigated. The authors investigated whether ectopic firing is elicited when the lumbar nerve root is exposed to nitric oxide using rats with and without cauda equina compression. A group of animals had partial L3 laminectomy, and a silicone tube was inserted in the epidural space to compress the cauda equina. A sham operation group and nontreated control group also were prepared. Seven days later, ectopic firing of the nerve root was recorded from the sural nerve. The animals with cauda equina compression showed significantly higher spontaneous firing rates than other groups. After a lumbar epidural administration of sodium nitroprusside, only the animals with cauda equina compression showed a marked increase in the firing rate. These results showed that the nerve roots became hyperexcitable under compression as indicated by increased spontaneous firing and marked sensitivity to nitric oxide. This mechanism may play an important role in the development of sciatica.

Animals↗
PubMed2003

A novel approach for high-quality microarray processing using third-dye array visualization technology.

Historically, microarray image processing has been technically challenging in obtaining quality gene expression data. After hybridization of Cy3- and Cy5-labeled samples, images are collected and processed to obtain gene expression ratio measurements for each of the elements on the array. The hybridization process often brings in contaminating noise, which can make correct identification of the signal difficult. In addition, spot intensity levels are highly variable due to the expression differences of different genes, and weak spots are often difficult to detect. These conditions are further complicated by inherent irregularities in spot position, shape, and size commonly found on high-density microarrays, making image processing an often labor-intensive task that is difficult to reliably automate. We previously reported a novel third-dye array visualization (TDAV) technology that allows prehybridization visualization and quality control of printed arrays. Here, we present a new microarray image processing approach utilizing TDAV. By incorporating the third-dye image, we show that overall quality of the microarray data is significantly improved, and automation of processing is feasible and reliable. Furthermore, we demonstrate use of the third-dye image to better quality control microarray image analysis. Both the principle and implementation of the approach are presented in detail, with experimental results.

Algorithms↗