Biomedical subjects

J Yang

Publications and source records attributed to J Yang.

At least 379 records · Page 21Linked to original sources

PubMed2001

[Effect of tissue-type plasminogen activator on differentiation of keratinocyte in the human embryonic epiderm].

OBJECTIVE: To explore the regulating roles of tissue-type plasminogen activator (tPA) in the differentiation of keratinocyte in the human epidermis. METHODS: Immunocytochemistry and in situ hybridization were employed to study tPA expression quantitatively and qualitatively in early, middle and late human embryos skin respectively. RESULTS: (1) The expression of tPA was significantly increased in the development of embryonic period, with the highest level in the middle embryonic phase, but the transcription of tPA still kept rather high level in the late human embryonic phase. (2) tPA was mainly localized in the superficial, more differentiated layers of the epidermis. (3) tPA was localized in peripheral cytoplasm of keratinocyte. CONCLUSION: tPA participates the regulation of the keratinocyte differentiation.

Cell Differentiation↗

PubMed2001

Intracellular redistribution of cardiac endothelin-1 receptor in rat during myocardial hypertrophy.

OBJECTIVE: In a model of rat cardiac hypertrophy, the changes in the distribution of ET-1 receptors in two subcellular fractions, the sarcolemma and the light vesicles during myocardial hypertrophy were studied. METHODS: Cardiac hypertrophy was produced by placing a constricting clip around the suprarenal abdominal aorta of rats, and ET-1 receptor was assayed with radioactive analysis method. RESULTS: It was found that plasma and ventricular ET-1 levels increased significantly on week 2 and week 4 of pressure overload. ET-1 binding studies showed that during myocardial hypertrophy, the maximum binding capacity (B(max)) was increased by 41% (P < 0.01) and 65% (P < 0.01) in sarcolemma in H-2 week and H-4 week groups, but was decreased by 24% (P < 0.01) and 21% (P < 0.01) in light vesicles. The sum of B(max) of sarcolemmal and light vesicle fractions was increased by 33% (P < 0.01) and 57% (P < 0.01) in group H-2 week and H-4 week, respectively. CONCLUSION: ET-1 receptors in rat heart were externalized from light vesicles to sarcolemma, which may contribute to the development of myocardial hypertrophy.

Animals↗

PubMed2001

Urotensin II receptor in the rat airway smooth muscle and its effect on the rat airway smooth muscle cells proliferation.

OBJECTIVE: To investigate the characteristics of urotensin II (U-II) receptor in the rat airway smooth muscle and the effect and signal transduction pathway of U-II on the proliferation of airway smooth muscle cells. METHODS: Using 125I-UII binding assay to measure the Bmax and Kd of U-II receptor. Using the 3H-TdR incorporation to determine the effect of U-II on the proliferation of airway smooth muscle cells and its signal transduction pathway. Using Fura-2/AM to measure the effect of U-1I on the cytosolic free calcium concentration. RESULTS: 1. 125I-UII binding increased with the time and reached saturation at 45 min. The B(max0 was (11.36 +/- 0.37)fmol/mg pr and Kd was (4.46 +/- 0.61) nmol/L. 2. U-II increased 3H-TdR incorporation of the airway smooth muscle cells in a dose-dependent manner. 3. H7, PD98059 and nicardipine, inhibitors of PKC, MAPK, calcium channel, respectively, significantly inhibited U-II-stimulated 3H-TdR incorporation of airway smooth muscle cells. W7, inhibitor of CaM-PK, had no effect. 4. Cyclosporin A, inhibitor of CaN, inhibited 3H-TdR incorporation of the airway smooth muscle cells induced by U-II in a dose-dependent manner. 5. U-II promoted cytosolic free calcium concentration increase by 18%. CONCLUSIONS: 1. There was U-II receptor in the rat airway smooth muscle. 2. The effect of U-II-stimulated 3H-TdR incorporation of airway smooth muscle cells was mediated by such signal transduction pathway as Ca2+, PKC, MAPK and CaN, etc.

Animals↗

PubMed2001

[Fluorescence enhancement and laser behavior of Rhodamine 6G in micell].

Fluorescence of Rhodamine 6G in aqueous solution is effectively enhanced by using anionic sodium dodecylsulfate (SDS) surfactant. When the concentration of Rhodamine 6G is 5.47 x 10(-7) mol.L-1 and 5.47 x 10(-4) mol.L-1, maximal enhancement ratio can be 1.95 and 9.7, respectively. In the latter case, using SDS can reduce the threshold and improve the energy conversion efficiency of the dye laser of Rhodamine 6G. In the absence of SDS, the laser threshold power density is near 65 MW.cm-2. While in the present of SDS, the threshold is reduced to 0.8 MW.cm-2. The laser energy conversion efficiency can reach 25% when the pumping power density is 65 MW.cm-2. We also observed the red shifts of absorption spectrum, fluorescence spectrum and the dye laser spectrum in the present of SDS. The physical mechanism of the phenomena is discussed.

Fluorescence↗

PubMed2001

[Molecular spectral diagnosis of star forming regions].

Stars are the basic building blocks of our universe, therefore it is one of the most important research topics in astrophysics to understand the origin and the early evolution of these objects. The current picture is that stars are formed during the collapse of a large enough self-gravitating interstellar molecular cloud. The early collapse gives birth to a fetus of a star, which is surrounded by a rotating accretion disk. The proto-star accretes interstellar matter through the disk which in turn transfer the accumulated matter to the central proto-star, then the star gets weight during the process. Observation shows that gorgeous ejection of matter always come along with the accretion process. In the presence of disks, these outflows usually escape from the system along the axis of the disk, forming so called bipolar outflows. Typical tracers of these activities are rich molecules such as CO, SiC2, C3H, C3H2 etc. Observationally, such typical molecular outflows can be detected using Doppler effect by spectroscopic measurements. Using the 13.7 m radio telescope in Delingha station of Purple Mountain Observatory, we performed a survey for 12 low temperature IRAS objects, some of the sources show high velocity properties. Detailed analysis of the Doppler profiles of IRS34 is presented. Star forming activities are clearly seen in this field.

English Abstract↗

PubMed2001

[Endometriosis in adolescents: analysis of 6 cases].

OBJECTIVE: To review the diagnosis and treatment of endometriosis in adolescents and to evaluate the surgical and medical treatment options for this special population. METHOD: To review the 6 cases of adolescent endometriosis and to review the literature research. RESULTS: Three hundred and ninety nine cases under age 18 had undergone gynecological operation. So the incidence among this period is 1.8% (6/339) in hospitalized adolescents. Four cases have complicated genital tract anomalies. Preoperative diagnosis is rare. Good prognosis is expected in most patients. Only 1 case relapsed 9 years after medical therapy. Endometriosis is the most common cause of chronic pelvic pain in adolescents. There may be a natural progression of endometriosis from atypical lesions in adolescents to classic lesions in adults. Congenital abnormalities of the reproductive tract are the main reason for the adolescent endometriosis. CONCLUSIONS: Endometriosis should be strongly suspected in adolescent with chronic pelvic pain especially with no response to oral contraceptives and nonsteroidal antiinflammatory medicine. The treatment involves the surgical operation and medicine. Adolescence;

Adolescent↗

PubMed2001

[Cross reticular bone grass used in slotted acetabular augmentation].

OBJECTIVES: To investigate the technique of cross reticular bone grass used in slotted acetabular augmentation ( SAA), and enrich the surgical procedures in the treatment of the DDH. METHODS: Thirty seven cases were treated with cross reticular bone grass used in SAA, including developmental dysplasia of the hip (DDH) and coaxial plana caused by Legg-Perthes disease. RESULTS: SAA provided an easy way to shape an adept acetabulum with cancellous bone graft. After the operation a stable hip was obtained. Thirty cases were good, 2 remained limping, 1 had a limitation of abduction of the hip. CONCLUSIONS: SAA is a safe and effective way to provide an adequate coverage of the femoral head. It is a developed shelf procedure with good stability and for a surgical frame of the hip. SAA method is safe and technically simple.

Acetabulum↗

PubMed2000

Decreased SLIM1 expression and increased gelsolin expression in failing human hearts measured by high-density oligonucleotide arrays.

BACKGROUND: Failing human hearts are characterized by altered cytoskeletal and myofibrillar organization, impaired signal transduction, abnormal protein turnover, and impaired energy metabolism. Thus, expression of multiple classes of genes is likely to be altered in human heart failure. METHODS AND RESULTS: We used high-density oligonucleotide arrays to explore changes in expression of approximately 7000 genes in 2 nonfailing and 2 failing human hearts with diagnoses of end-stage ischemic and dilated cardiomyopathy, respectively. We report altered expression of (1) cytoskeletal and myofibrillar genes (striated muscle LIM protein-1 [SLIM1], myomesin, nonsarcomeric myosin regulatory light chain-2 [MLC(2)], and ss-actin); (2) genes responsible for degradation and disassembly of myocardial proteins (alpha(1)-antichymotrypsin, ubiquitin, and gelsolin); (3) genes involved in metabolism (ATP synthase alpha-subunit, succinate dehydrogenase flavoprotein [SDH Fp] subunit, aldose reductase, and TIM17 preprotein translocase); (4) genes responsible for protein synthesis (elongation factor-2 [EF-2], eukaryotic initiation factor-4AII, and transcription factor homologue-HBZ17); and (5) genes encoding stress proteins (alphaB-crystallin and mu-crystallin). In 5 additional failing hearts and 4 additional nonfailing controls, we then compared expression of proteins encoded by the differentially expressed genes, alphaB-crystallin, SLIM1, gelsolin, alpha(1)-antichymotrypsin, and ubiquitin. In each case, changes in protein expression were consistent with changes in transcript measured by microarray analysis. Gelsolin protein expression was also increased in cardiomyopathic hearts from tropomodulin-overexpressing (TOT) mice and rac1-expressing (racET) mice. CONCLUSIONS: Altered expression of the genes identified in this study may contribute to development of the heart failure phenotype and/or represent compensatory mechanisms to sustain cardiac function in failing human hearts.

Adolescent↗

PubMed2000

Expression and fast-flow purification of a polyhistidine-tagged myoglobin-like aerotaxis transducer.

A Co(2+)-affinity, fast-flow perfusion chromatography method to purify a polyhistidine-tagged myoglobin-like aerotaxis transducer HemAT-Hs has been developed. The method relies upon a six-histidine affinity tag fused to the C-terminus and N-terminus of HemAT-Hs for expression in the native host, an extremely halophilic Archaeon Halobacterium salinarum, and in the heterologous host Escherichia coli, respectively. The His-tagged HemAT-Hs can be purified rapidly using either low or high ionic strength buffers. Purified His-tagged HemAT-Hs in high or low salt buffers demonstrated no difference in spectral characteristics and retained reversible oxygen binding capacity. This fast-flow Co(2+)-affinity perfusion chromatography provides a simple method for preparation of halophilic heme containing soluble proteins for biophysical and structural studies.

Archaeal Proteins↗

PubMed2000

Characterization of Epstein-Barr virus-infected B cells in patients with posttransplantation lymphoproliferative disease: disappearance after rituximab therapy does not predict clinical response.

Post-transplantation lymphoproliferative disease (PTLD) is associated with Epstein-Barr virus (EBV). Quantitative and qualitative differences in EBV in peripheral blood mononuclear cells (PBMCs) of PTLD patients and healthy controls were characterized. A quantitative competitive polymerase chain reaction (QC-PCR) technique confirmed previous reports that EBV load in PBMCs is increased in patients with PTLD in comparison with healthy seropositive controls (18 539 vs 335 per 10(6) PBMCs, P =.0002). The average frequency of EBV-infected cells was also increased (271 vs 9 per 10(6) PBMCs, P =.008). The distribution in numbers of viral genome copies per cell was assessed by means of QC-PCR at dilutions of PBMCs. There was no difference between PTLD patients and healthy controls. Similarly, no differences in the patterns of viral gene expression were detected between patients and controls. Finally, the impact of therapy on viral load was analyzed. Patients with a past history of PTLD who were disease-free (after chemotherapy or withdrawal of immunosuppression) at the time of testing showed viral loads that overlapped with those of healthy seropositive controls. Patients treated with rituximab showed an almost immediate and dramatic decline in viral loads. This decline occurred even in patients whose PTLD progressed during therapy. These results suggest that the increased EBV load in PBMCs of PTLD patients can be accounted for by an increase in the number of infected B cells in the blood. However, in terms of viral copy number per cell and pattern of viral gene expression, these B cells are similar to those found in healthy controls. Disappearance of viral load with rituximab therapy confirms the localization of viral genomes in PBMCs to B cells. However, the lack of relationship between the change in viral load and clinical response highlights the difference between EBV-infected PBMCs and neoplastic cells in PTLD.

Adult↗

PubMed2000

The effect of preoperative transcatheter hepatic arterial chemoembolization on disease-free survival after hepatectomy for hepatocellular carcinoma.

BACKGROUND: Although surgical resection has produced better results than other therapies for local control of hepatocellular carcinoma (HCC), the long term results have not been satisfactory because of a low disease-free survival rate. The effects of preoperative transcatheter arterial chemoembolization (TACE) on improving disease-free survival of HCC after hepatectomy has remained controversial. METHODS: The current study was retrospective survey of 1725 patients who had hepatectomy for HCC between January 1990 and December 1995 and had follow-up data for 1457 cases. The follow-up rate was 84.5%. The significant prognostic factors were analyzed using a Cox proportional hazards survival model, and the disease-free survival was calculated by Kaplan-Meier estimation. Among 1457 cases, 120 patients underwent preoperative TACE and were divided into a one time TACE group, over two times TACE group, an effective group, and ineffective group. RESULTS: Multivariate analyses revealed significant prognostic factors as follows: preoperative TACE number, preoperative TACE effect, preoperative lesion number, intraoperative tumor thrombus, tumor size, tumor gross type, daughter nodules, vascular invasion, and postoperative alpha-fetoprotein value. Kaplan-Meier estimation showed that the 5-year disease-free survival rates of the over two times group, the one time group, and no TACE group were 51.0%, 35.5%, and 21.4%, respectively, and that the mean disease-free survival times of the three groups were 66.4, 22.5 and 12.5 months, respectively. The effective group had a 5-year disease-free survival rate of 56.8%, with a mean time of 90.1 months. CONCLUSIONS: Effective preoperative TACE may be one of the best methods, which can be clinically performed at present, for resectable HCCs including small HCCs for improving disease-free survival after hepatectomy. According to tumor size, range, location, hepatic function, and TACE effect, TACE can be performed 2-4 times preoperatively within 6 months.

Adolescent↗

PubMed2000

Independent signals control expression of the calcineurin inhibitory proteins MCIP1 and MCIP2 in striated muscles.

Calcineurin, a calcium/calmodulin-regulated protein phosphatase, modulates gene expression in cardiac and skeletal muscles during development and in remodeling responses such as cardiac hypertrophy that are evoked by environmental stresses or disease. Recently, we identified two genes encoding proteins (MCIP1 and MCIP2) that are enriched in striated muscles and that interact with calcineurin to inhibit its enzymatic activity. In the present study, we show that expression of MCIP1 is regulated by calcineurin activity in hearts of mice with cardiac hypertrophy, as well as in cultured skeletal myotubes. In contrast, expression of MCIP2 in the heart is not altered by activated calcineurin but responds to thyroid hormone, which has no effect on MCIP1. A approximately 900-bp intragenic segment located between exons 3 and 4 of the MCIP1 gene functions as an alternative promoter that responds to calcineurin. This region includes a dense cluster of 15 consensus binding sites for NF-AT transcription factors. Because MCIP proteins can inhibit calcineurin, these results suggest that MCIP1 participates in a negative feedback circuit to diminish potentially deleterious effects of unrestrained calcineurin activity in cardiac and skeletal myocytes. Inhibitory effects of MCIP2 on calcineurin activity may be pertinent to gene switching events driven by thyroid hormone in striated muscles. The full text of this article is available at http://www. circresaha.org.

Animals↗

PubMed2000

P-Selectin glycoprotein ligand 1 (PSGL-1) is a physiological ligand for E-selectin in mediating T helper 1 lymphocyte migration.

P-selectin glycoprotein ligand 1 (PSGL-1) is a sialomucin expressed on leukocytes that mediates neutrophil rolling on the vascular endothelium. Here, the role of PSGL-1 in mediating lymphocyte migration was studied using mice lacking PSGL-1. In a contact hypersensitivity model, the infiltration of CD4(+) T lymphocytes into the inflamed skin was reduced in PSGL-1-deficient mice. In vitro-generated T helper (Th)1 cells from PSGL-1-deficient mice did not bind to P-selectin and migrated less efficiently into the inflamed skin than wild-type Th1 cells. To assess the role of PSGL-1 in P- or E-selectin-mediated migration of Th1 cells, the cells were injected into E- or P-selectin-deficient mice. PSGL-1-deficient Th1 cells did not migrate into the inflamed skin of E-selectin-deficient mice, indicating that PSGL-1 on Th1 cells is the sole ligand for P-selectin in vivo. In contrast, PSGL-1-deficient Th1 cells migrated into the inflamed skin of P-selectin-deficient mice, although less efficiently than wild-type Th1 cells. This E-selectin-mediated migration of PSGL-1-deficient or wild-type Th1 cells was not altered by injecting a blocking antibody to L-selectin. These data provide evidence that PSGL-1 on Th1 cells functions as one of the E-selectin ligands in vivo.

Adjuvants, Immunologic↗

PubMed2000

Dendritic cell elimination as an assay of cytotoxic T lymphocyte activity in vivo.

We show in this paper that the survival of antigen-loaded dendritic cells in vivo may be used as a sensitive readout of CTL activity. We have previously shown that dendritic cells labeled with the fluorescent dye CFSE and injected sub-cutaneously into mice migrate spontaneously to the draining lymph node where they persist for several days. In the presence of effector CTL responses, dendritic cells loaded with specific antigen rapidly disappear from the draining lymph node. In this paper we extend the above observations and set up a simple and sensitive method to reveal CTL activity in individual mice in vivo. Dendritic cells were labeled with two different fluorochromes, loaded with antigen or left untreated, and mixed together before injection into mice. We show that only the dendritic cells loaded with specific antigen were cleared from the draining lymph node, while dendritic cells not loaded with antigen remained unaffected. Cytotoxic responses generated by immunization with peptide-loaded dendritic cells, or by infection with influenza virus, could be revealed using this method. Comparison of the differential survival of dendritic cells populations mixed together also allowed us to accurately evaluate the disappearance of dendritic cells, irrespective of variability in the injection site and other parameters. Given the ability of dendritic cells to efficiently take up and present complex antigens, nucleic acids and apoptotic bodies, this method may also allow the evaluation of cytotoxic activity against antigens that are not characterized in terms of peptide epitopes.

Animals↗

PubMed2000

Human glioma cell BT325 expresses a proteinase that converts human plasminogen to kringle 1-5-containing fragments.

Angiostatin, a specific angiogenesis inhibitor, is an internal fragment of plasminogen, and can be generated in many systems mediated by different enzymes in vitro. The mechanism of angiostatin generation in vivo has not been well defined. Here we demonstrated that human glioma cell line BT325 can express an enzyme that can convert purified plasminogen to angiostatin-like fragments with molecular masses of 65, 60, and 58 kDa, respectively. These fragments have an identical N-terminal as KVYLS, which starts from Lys(98) of the plasminogen precusor. According to their molecular mass, the three fragments should comprise kringle domain 1 to kringle domain 5 (kringle 1-5). The proteolytic fragments obtained as above can inhibit the growth of bovine aortic endothelial (BAE) cells specifically. The proteolysis process can be completely inhibited by serine proteinase inhibitors, and partially inhibited by EDTA. The molecular weight of the peptide, which contains an enzymatic activity responsible for the proteolysis, was 13 kD determined by gel filtration and SDS-PAGE. The present data suggest that glioma cell BT325 can produce a novel proteinase to generate kringle 1-5 of plasminogen as an angiogenesis inhibitor.

Amino Acid Sequence↗

PubMed2000

Differential expression of cocaine- and amphetamine-regulated transcript-immunoreactivity in the rat spinal preganglionic nuclei.

The distribution of cocaine- and amphetamine-regulated transcript-like immunoreactivity (CART-LI) was investigated in the rat spinal cords with the use of an antiserum against the CART peptide fragment 55-102. CART-LI fibers were concentrated in the superficial layers of the dorsal horn of all segments. In addition to CART-LI fibers, intensely labeled somata were detected in the intermediolateral cell column (IML) and other sympathetic preganglionic nuclei of the thoracolumbar segments. In the lumbosacral segments, CART-LI fibers but not somata were seen in the sacral parasympathetic nucleus. Double-labeling the spinal sections with choline acetyltransferase (ChAT)-antisera and CART-antisera revealed that the large majority of ChAT-positive somata in the sympathetic preganglionic nuclei were CART-positive, whereas ChAT-positive somata in the parasympathetic preganglionic nuclei were CART-negative. Our results show that CART-LI is selectively expressed in a population of sympathetic preganglionic neurons (SPNs), but not in parasympathetic preganglionic neurons (PPNs) of the rat.

Animals↗

PubMed2000

Crucial role of kainate receptors in mediating striatal kainate injection-induced decrease in acetylcholine M(1) receptor binding in rat forebrain.

We investigated the roles of kainate-, alpha-amino-3-hydroxy-5-methylisoxazol-4-propionate (AMPA)- and N-methyl-D-aspartate (NMDA)-receptors in mediating striatal kainate injection-induced decrease in the binding of acetylcholine M(1) receptors in rat forebrain. After unilateral intrastriatal injection of kainate (4 nmol), the bindings of [3H]kainate (10 nM), [3H]MK-801 (4 nM) and [3H]pirenzepine (4 nM) to the rat ipsilateral forebrain membranes declined, reaching the lowest on day 2 to 4 and recovering on day 8. Saturation binding studies, performed on day 2 post-injection, showed that kainate (1, 2, 4 nmol) dose-dependently decreased B(max) and K(d) of the three ligands. (+)-5-Methyl-10, 11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine (MK-801), a selective NMDA receptor channel blocker, antagonised (from a dose of 4 nmol) kainate-induced decreases in the bindings of [3H]kainate (up to approximately 20%), [3H]MK-801 (up to approximately 90%) and [3H]pirenzepine (up to approximately 70%). In contrast, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), a selective non-NMDA receptor antagonist, almost completely abolished (from a dose of 12 nmol) kainate-induced decreases in the bindings of all the three ligands (up to approximately 95-98%). Cyclothiazide, a selective potentiator that enhances AMPA receptor-mediated responses, significantly enhanced (from a dose of 4 nmol) kainate-induced decrease in the binding of [3H]kainate but not that of [3H]pirenzepine or [3H]MK-801. In summary, these results indicate that striatal kainate injection-induced decrease in the binding of acetylcholine M(1) receptors in rat forebrain is dependent on activation of kainate receptors and, to a certain extent, a consequent involvement of NMDA receptors. These and previous studies provide some evidence showing that kainate receptors might play a crucial role in regulating excitatory amino acids (EAA)-modulated cholinergic neurotransmission in the central nervous system (CNS).

6-Cyano-7-nitroquinoxaline-2,3-dione↗

PubMed2000

Combinatorial control of cyclin B1 nuclear trafficking through phosphorylation at multiple sites.

Entry into mitosis is regulated by the Cdc2 kinase complexed to B-type cyclins. We and others recently reported that cyclin B1/Cdc2 complexes, which appear to be constitutively cytoplasmic during interphase, actually shuttle continually into and out of the nucleus, with the rate of nuclear export exceeding the import rate (). At the time of entry into mitosis, the import rate is increased, whereas the export rate is decreased, leading to rapid nuclear accumulation of Cdc2/cyclin B1. Although it has recently been reported that phosphorylation of 4 serines within cyclin B1 promotes the rapid nuclear translocation of Cdc2/cyclin B1 at G(2)/M, the role that individual phosphorylation sites play in this process has not been examined (, ). We report here that phosphorylation of a single serine residue (Ser(113) of Xenopus cyclin B1) abrogates nuclear export of cyclin B1. This serine lies directly within the cyclin B1 nuclear export sequence and, when phosphorylated, prevents binding of the nuclear export factor, CRM1. In contrast, analysis of phosphorylation site mutants suggests that coordinate phosphorylation of all 4 serines (94, 96, 101, and 113) is required for the accelerated nuclear import of cyclin B1/Cdc2 characteristic of G(2)/M. Additionally, binding of cyclin B1 to importin-beta, the factor known to be responsible for the slow interphase nuclear entry of cyclin B1, appears to be unaffected by the phosphorylation state of cyclin B. These data suggest that a distinct import factor must be recruited to enhance nuclear entry of Cdc2/cyclin B1 at the G(2)/M transition.

Active Transport, Cell Nucleus↗