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Biomedical subjects

Zhen Yang

Publications and source records attributed to Zhen Yang.

At least 55 records · Page 3Linked to original sources
PubMed2005

Development of a biosensor for measuring plasma fibrinogen based on an enzyme kinetic model.

A biosensor has been designed for measuring plasma fibrinogen concentrations based on an enzyme kinetic model. The values obtained correspond linearly to those of a clinical method but have a higher sensitivity within the normal range of fibrinogen. By using the disposable biosensor technology, this method is easy to follow, quick (within 2 min) and precise (with coefficients of variation to be as low as below 5%) and requires only a small amount of plasma sample (<50 microl). This biosensor technology also holds potential for use in point-of-care diagnostics.

Animals↗
PubMed2005

Arabidopsis ERF4 is a transcriptional repressor capable of modulating ethylene and abscisic acid responses.

ERFs (ethylene-responsive element binding factors) belong to a large family of plant transcription factors that are found exclusively in plants. A small subfamily of ERF proteins can act as transcriptional repressors. The Arabidopsis genome contains eight ERF repressors, namely AtERF3, AtERF4, and AtERF7 to AtERF12. Members of ERF repressors show differential expression, suggesting that they may have different function. Using a transient expression system, we demonstrated that AtERF4, AtERF7, AtERF10, AtERF11 and AtERF12 can function as transcriptional repressors. The expression of AtERF4 can be induced by ethylene, jasmonic acid, and abscisic acid (ABA). By using green fluorescent protein fusion, we demonstrated that AtEFR4 accumulated in the nuclear bodies of Arabidopsis cells. Expression of 35S:AtERF4-GFP in transgenic Arabidopsis plants conferred an ethylene-insensitive phenotype and repressed the expression of Basic Chitinase and beta-1,3-Glucanase, the GCC-box-containing genes. In comparison with wild-type plants, 35S:AtERF4-GFP transgenic plants had decreased sensitivity to ABA and were hypersensitive to sodium chloride. The expression of the ABA responsive genes, ABI2, rd29B and rab18, was decreased in the 35S:AtERF4-GFP transgenic plants. Our study provides evidence that AtERF4 is a negative regulator capable of modulating ethylene and abscisic acid responses.

Abscisic Acid↗
PubMed2005

Subcellular localization and membrane association of SARS-CoV 3a protein.

SARS-CoV 3a protein was a unique protein of SARS coronavirus (SARS-CoV), which was identified in SARS-CoV infected cells and SARS patients' specimen. Recent studies revealed that 3a could interact specifically with many SARS-CoV structural proteins, such as M, E and S protein. Expressed 3a protein was reported to localize to Golgi complex in SARS-CoV infected cells. In this study, it was shown that 3a protein was mainly located in Golgi apparatus with different tags at N- or C-terminus. The localization pattern was similar in different transfected cells. With the assay of truncated 3a protein, it was shown that 3a might contain three transmembrane regions, and the second or third region was properly responsible for Golgi localization. By ultra-centrifugation experiment with different extraction buffers, it was confirmed that 3a was an integral membrane protein and embedded in the phospholipid bilayer. Immunofluorescence assay indicated that 3a was co-localized with M protein in Golgi complex in co-transfected cells. These results provide a new insight for further study of the 3a protein on the pathogenesis of SARS-CoV.

Animals↗
PubMed2005

[Impaired endothelium-dependent vasodilation and arterial elasticity in patients with coronary artery disease].

OBJECTIVE: To investigate the change in endothelium-dependent vasodilation and arterial elasticity and the association between them in patients with coronary artery disease (CAD). METHODS: Thirty patients with CAD and thirty control subjects were recruited for this study. Flow-mediated dilation (FMD) in the brachial artery was evaluated by ultrasound Doppler flow method. They also underwent a non-invasive assessment of C(1) large artery and C(2) small artery indices by using pulse wave analysis. RESULTS: FMD was significantly reduced in CAD group compared with that in control group [(5.17 +/- 2.13)% vs (11.1 +/- 4.36)%, P < 0.05], C(1) large artery elasticity index was similar between the two groups [(11.59 +/- 4.56) ml/mm Hg x 10 vs (12.11 +/- 3.82) ml/mm Hg x 10, P > 0.05]. However, C(2) small artery elasticity index was significantly reduced in CAD group compared with that in control group [(4.20 +/- 1.80) ml/mm Hg x 100 vs (6.26 +/- 2.36) ml/mm Hg x 100, P < 0.05]. There was a positive association between reduced C(2) small artery elasticity index and impaired FMD (r = 0.53, P < 0.05). CONCLUSIONS: There were impaired endothelium-dependent vasodilation and reduced C(2) small artery elasticity index in the patients with CAD, which were closely correlated with each other. The present study suggested that the measurement of C(2) small artery elasticity might be used as a novel index for the determination of endothelial function.

Aged↗
PubMed2005

[A study of association between age-related circulating endothelial progenitor cells and arterial elasticity].

OBJECTIVE: Reduced arterial elasticity is a hallmark of aging in healthy humans independently of diseases and endothelial-cell injury and dysfunction may be responsible for this fall in arterial elasticity. We hypothesized that circulating endothelial progenitor cells (EPCs) are involved in endothelial repair and that lack of EPCs contributes to impaired arterial elasticity. METHODS: A total of 56 healthy male volunteers were divided into young (n = 26) and elderly (n = 30) groups. Large and small artery elasticity indices were non-invasively assessed by using pulse wave analysis. Flow cytometer was used to count the number of circulating CD34(+) mononuclear cells (MNCs), which were isolated from peripheral blood by Ficoll density gradient centrifugation, and then the cells were plated on fibronectin-coated culture dishes. EPCs were characterized as adherent cells double positive staining for DiI-acLDL uptake and lectin binding with using fluorescent microscope. RESULTS: C(1) (large artery elasticity index) and C(2) (small artery elasticity index) were significantly reduced in the elderly group compared with those in the young group (11.73 +/- 1.45 vs 16.89 +/- 1.69 ml/mm Hg x 10, P < 0.001; 8.40 +/- 1.45 vs 10.58 +/- 1.18 ml/mm Hg x 100, P < 0.001 respectively). In parallel, the number of circulating EPCs was significantly reduced in the elderly group compared with the young group (0.13 +/- 0.02 vs 0.17 +/- 0.04%, P < 0.05). The number of circulating EPCs correlated with C(1) large and C(2) small artery elasticity indices (r = 0.47, P < 0.01; r = 0.4, P < 0.01). Fluorescent microscope was used to identify EPCs, which were double positive staining for DiI-acLDL uptake and lectin binding. CONCLUSION: The present findings suggested that the fall in circulating EPCs with subsequently impaired endothelial-cell repair and function might contribute to reduced arterial elasticity in humans with aging. The decrease in circulating EPCs could serve as a surrogate biologic measure of vascular function and human age.

Adult↗
PubMed2005

[Fluid shear stress regulates secretion of tissue-type plasminogen activator in human endothelial progenitor cells].

OBJECTIVE: In order to investigate the role of shear stress in the regulation of endothelial function, we assessed here effects of shear stress on tissue-type plasminogen activator in human endothelial progenitor cells (EPCs). METHODS: The peripheral blood mononuclear cells were separated from healthy adult and inducted into EPCs, which were identified by double staining for the fluorescent labeled acetylated-LDL and lectin. EPCs were seeded on the small diameter artificial vessels, and then divided into four different experimental groups including stationary group, low-flow shear stress group (5 dyn/cm(2)), medium-flow shear stress group (15 dyn/cm(2)) and high-flow shear stress group (25 dyn/cm(2)). The levels of t-PA in EPC culture medium at 0 hour, 5 hours, 10 hours, 15 hours, 20 hours and 25 hours after culture were measured by enzyme-linked immunosorbent assay. RESULTS: The peripheral blood mononuclear cells differentiated into EPCs after induction, which were positively labeled by fluorescent acetylated-LDL and lectin. Shear stress enhanced production of the t-PA by EPCs, which was paralleled to levels and times of shear stress. CONCLUSIONS: Shear stress increases t-PA secretion by human EPCs, suggesting that shear stress not only regulates vascular endothelial function but also participates in the pathogenesis of arteriosclerosis.

Adult↗
PubMed2005

[Reconstruction of mandibular defect caused by resection of oral carcinoma with pectoralis major myocutaneous flap and ti-plate system].

OBJECTIVE: To investigate the clinical effect of the pectoralis major myocutaneous flap and Ti-plate system in repairing mandibular defects caused by resection of oral carcinoma. METHODS: From November 2001 to February 2003, 32 patients with mandibular defect caused by resection of oral carcinoma were treated. Combined radical neck dissection with resection of gingival and mandible was performed on 11 patients with carcinoma of the lower gingival, combined radical neck dissection with glossectomy and mandibulectomy on 13 patients with carcinoma of tongue, combined radical neck dissection with resection of floor of mouth and mandible on 4 patients with carcinoma of floor of mouth, and combined radical neck dissection with resection of cheek and mandible on 4 patients with carcinoma of buccal mucosa, respectively. The defects of mandible were associated with soft-tissue component, the sizes of defect ranged from 5.5 cm x 7.6 cm to 8. 2 cm x 10.5 cm. The defects were reconstructed with 6 cm x 7 cm to 9 cm x 10 cm pectoralis major myocutaneous flaps and Ti-plate system. The effect was studied retrospectively. RESULTS: Thirty-two cases were followed for 2-19 months; 29 cases of flaps survived and 3 cases of flaps partly necrosed (10% or less of the skin paddle). The appearance of face was satisfactory in 27 patients, and slight deformity of face was observed in 5 patients. The occluding relation and masticatory function were recovered well. Opening mouth extents ranged from 2.7 cm to 3.4 cm. No temporomandibular arthrosis relating to operation was found in all cases. CONCLUSION: A combination of the pectoralis major myocutaneous flap and Ti-plate system is an ideal method for reconstruction of mandible defects associated with soft-tissue component after radical operation of oral carcinoma.

Adult↗
PubMed2005

[Mutation screening of GCK gene in Chinese early-onset diabetes population].

OBJECTIVE: To investigate the prevalence of mutations and sequence variations of glucokinase gene GCK in Chinese early-onset diabetes population. METHODS: The study was conducted in 174 unrelated Chinese residents, including 80 nondiabetic controls, 94 probands of early-onset diabetes pedigree. Direct sequencing was performed to screen all 10 exons of glucokinase gene, including promoter and exon/intron junctions. RESULTS: No mutations were identified in coding region, but several previously reported sequence variants were identified. 5'-untranslated region of exon 1a, 84 bp upstream of the translation initiation site GGCGG to GGGGG(early-onset diabetes group G allele frequency 0.106 vs control group 0.075, P=0.355); IVS1b+12 (A-->T) (early-onset diabetes group T allele frequency 0.005 vs non-identity of this variation in control group); IVS 5+29 (G-->T) (early-onset diabetes group T allele frequency 0.027 vs control group 0.019, P=0.731); IVS 9+8 (T-->C) (early-onset diabetes group C allele frequency 0.585 vs 0.694, P=0.044). A novel variation IVS 9+49 (G-->A) (early-onset diabetes group A allele frequency 0.011 vs control 0.006, P=1.000) was identified. There were no significant relationships of the exon 1a 5'-untransted region -84 bp(C-->G), IVS 5+29 (G-->T), IVS 9+8 (T-->C) and IVS 9+49 (G-->A) variants of GCK gene to the clinical variables such as plasma glucose, insulin, C-peptide and fasting lipid profile. CONCLUSION: The prevalence of structural mutations in glucokinase gene responsible for early-onset diabetes appears to be rare among Chinese patients.

Adult↗
PubMed2005

[The study on donor site sequelae after autologous breast reconstruction with an extended latissimus dorsi flap].

OBJECTIVE: To study the prevention and treatment on the donor site sequelae after autologous breast reconstruction with extended latissimus dorsi flap. METHODS: 88 patients received breast reconstruction with extended latissimus dorsi flap between May 1999 and Nov 2004 were concerned. We analyzed the donor site sequelae by objective and subjective evaluation and we assessed the functional condition. Results Dorsal hematoma developed in 1 patient. There are 7 patients with dorsal seromas and 2 of them developed capsules; 5 patients with mild skin exfoliate and 1 patient with dry skin necrosis, 2 winged shoulders. No infection and no hypertrophic scars appeared in donor site. There is no significant functional limitation and no influence in daily life. CONCLUSIONS: The main complication after autologous breast reconstruction with extended latissimus dorsi flap was seromas and it can be controlled to decrease. There is no severe complication. It's a worthy method in autologous breast reconstruction in oriental people.

Adult↗
PubMed2005

[Change in endothelial progenitor cells and endothelial function in patients with unstable angina pectoris].

OBJECTIVE: To investigate the relationship between endothelial progenitors cells (EPCs) and endothelium-dependent vasodilation in patients with unstable angina pectoris. METHODS: Thirty patients with unstable angina pectoris (UAP) and thirty control subjects were recruited. Flow-mediated dilation (FMD) in the brachial artery was evaluated by using ultrasound Doppler flow method. The number of circulating EPCs was analyzed by flow cytometry analysis. Total mononuclear cells were isolated from peripheral blood by Ficoll density gradient centrifugation, and then the cells were plated on fibronectin-coated culture dishes. CD34 antigen of adherent cells was identified by immunohistochemical assay. EPCs were characterized as adherent cells double positive for FITC-UEA-I binding and DiI-acLDL uptake by direct fluorescent staining under inverted fluorescent microscope. RESULTS: FMD was significantly impaired in the UAP group compared with the control group (5.93% +/- 2.67% vs 11.1% +/- 4.36%, P < 0.05). There was no significant difference in NMD between two groups (13.60% +/- 5.03% vs 14.18% +/- 4.50%, P > 0.05). The number of CD34(+) cells significantly increased in the UAP group compared with the control group (0.13% +/- 0.05% vs 0.09% +/- 0.04%, P < 0.05). There was a negative association between impaired FMD and increased CD34(+) cell (r = -0.385, P < 0.05). A positive antigen of CD34 of adhesion cells and double positive adhesion cells were found. CONCLUSION: This study shows that the levels of peripheral CD34(+) cells in patients with UAP increase with an impaired endothelial function. The increase in EPCs may be an important compensatory response to acute coronary ischemia and impaired endothelium in patients with UAP.

Aged↗
PubMed2005

[Tumor necrosis factor-alpha induces release of endothelial microparticles from human endothelial cells].

OBJECTIVE: The present study was designed to investigate whether Tumor necrosis factor (TNF)-alpha stimulates release of endothelial microparticles (EMPs) by human endothelial cells, and whether EMPs may serve as a promising marker for endothelial injury and dysfunction. METHODS: Human umbilical venous endothelial cells (HUVEC) were incubated with or without TNF-alpha for 24 hours at 37 degrees C. EMPs generated on the surface of HUVEC were observed with a scanning electron microscopy. The CD31 and CD51 positive EMPs in culture supernatants were measured by flow cytometer. RESULTS: Fewer vesicles were observed on cell surface of control group, in TNF-alpha-stimulated one, however, cells manifested a blebby surface (eruption phenomenon) and more vesicles on surface were observed. The levels of EMPs were significantly increased in TNF-alpha stimulated cells compared with controls [CD31 + EMP, (164 +/- 63)/1000 cells vs. (42 +/- 10)/1000 cells, P < 0.05; CD51 + EMP, (260 +/- 108)/1000 cells vs. (19 +/- 4)/1000 cells, P < 0.05]. CONCLUSION: TNF-alpha can stimulate HUVEC to release EMPs which may serve as a surrogate marker for endothelial injury and dysfunction.

Cells, Cultured↗
PubMed2004

Prenatal environmental tobacco smoke exposure promotes adult atherogenesis and mitochondrial damage in apolipoprotein E-/- mice fed a chow diet.

BACKGROUND: Environmental tobacco smoke (ETS) exposure is recognized as a cardiovascular disease risk factor; however, the impact of prenatal ETS exposure on adult atherogenesis has not been examined. We hypothesized that in utero ETS exposure promotes adult atherosclerotic lesion formation and mitochondrial damage. METHODS AND RESULTS: Atherosclerotic lesion formation, mitochondrial DNA damage, antioxidant activity, and oxidant load were determined in cardiovascular tissues from adult apolipoprotein E-/- mice exposed to either filtered air or ETS in utero and fed a standard chow diet (4.5% fat) from weaning until euthanasia. All parameters were significantly altered in male mice exposed in utero to ETS. CONCLUSIONS: These data support the hypothesis that prenatal ETS exposure is sufficient to promote adult cardiovascular disease development.

Animals↗
PubMed2004

Precise analysis of the components of diffraction by cylindrical crystals.

A detailed quantitative analysis of the various Bragg and Laue components of the integrated reflection power ratio for cylindrical crystals, and the dependence of these components on the Bragg angle, thetaB, the reduced radius, tau0 = sigma0rho, and the ratio of absorption coefficient to diffraction cross section, mu/sigma0 = xi0, is presented. The result indicates that the percentage of Laue and Bragg components of the integrated reflection power ratio is larger than 50% when thetaB < or = 20 degrees and murho < or = 1, and when thetaB > or = 10 degrees and murho > or = 5. The reflection power ratio profile for cylindrical crystals with large murho is also discussed.

Journal Article↗
PubMed2004

Synthesis of novel palladacycles and their application in Heck and Suzuki reactions under aerobic conditions.

[reaction: see text] Design and synthesis of a novel family of furancarbothioamide-based palladacycles are reported herein. These palladacycles are thermally stable, not sensitive to air or moisture, and are applied effectively in the Heck reaction of aryl halides with terminal olefins and in the Suzuki reaction of aryl halides with arylboronic acids. These reactions were performed under aerobic conditions, leading to turnover numbers (TONs) up to 1 x 10(5).

Journal Article↗
PubMed2004

Concise synthesis of isoquinoline via the Ugi and Heck reactions.

[reaction: see text] Two types of isoquinoline scaffolds were successfully constructed in a combinatorial format via the Ugi four-component reaction and the Pd-catalyzed intramolecular Heck reaction, starting from readily available starting materials.

Combinatorial Chemistry Techniques↗
PubMed2004

[Factors of avascular necrosis of femoral head and osteoporosis in SARS patients' convalescence].

OBJECTIVE: To explore the factors affecting the pathogenesis of avascular necrosis of femoral head and osteoporosis of SARS patients during convalescent stage. METHODS: The clinical data of 40 SARS patients, 12 males and 28 females, aged 29 +/- 9, hospitalized from April to June 2003, were reviewed, targeted on the use of glucocorticoids. Three months after the discharge ELISA and indirect immunofluorescent antibody (IFA) assay were used to detect the serum IgG. Magnetic resonance imaging (MRI) was used to detect the damage of the head of femur and quantitative ultrasound (QUS) was used to detect osteoporosis at the left heel. RESULTS: The average total dosage of methylprednisolone was (4949 +/- 2959) mg, and the average course of treatment was (24 +/- 5) days (16 to 30 days). Twenty-three patients underwent ictus therapy of corticosteroids for (8 +/- 4) days. The extenuation time of corticosteroid' dosage was (33 +/- 26) mg/d. Of the 40 patients, 36 were IgG positive with an average A value of (0.91 +/- 0.24) and 4 patients were IgG negative. Twelve patients (30%) were with type I avascular necrosis of femoral head, including 3 cases with unilateral left--necrosis and 9 cases of bilateral necrosis. The other 28 patients were without necrosis. Two patients were suffering from osteoporosis and 30 patients were with bone density decrement. The average Z values of the parameter BUA and VOS were (-1.26 +/- 0. 53) and (-0.53 +/- 0.30) respectively. The corresponding T values of the parameter BUA and VOS were (-1.49 +/- 0.59) and (-0.65 +/- 0.05) respectively. The influencing factors of femoral necrosis included the degree of healing activity, the dosage summation of corticosteroids, and length of ictus therapy. The influencing factors of bone density included age, dosage summation, and length of ictus therapy. The influencing factors of the bone fabric and flexibility included the use and length of ictus therapy. Statistics showed that serum IgG was not related with avascular necrosis of femoral head and osteoporosis. CONCLUSIONS: The incidence rates of avascular necrosis of femoral head and of osteoporosis were higher in convalescent SARS patients than in general population. The influencing factors of femoral necrosis included the degree of healing activity, the dosage summation of corticosteroids, and length of ictus therapy. The influencing factors of bone density included age, dosage summation, and length of ictus therapy. The influencing factors of the bone fabric and flexibility included the use and length of ictus therapy. Statistics showed that serum IgG was not related with avascular necrosis of femoral head and osteoporosis. SARS virus may not affect the pathogenesis of avascular necrosis of femoral head and osteoporosis.

Adolescent↗
PubMed2004

[The study on correlation of c-myc gene expression with vascular smooth muscle cell proliferation in patients with portal hypertension].

OBJECTIVE: To investigate c-myc proto-oncogene expression and the relationship of PCNA protein expression of extrahepatic vascular smooth muscle cell in patients with portal hypertension and normal vessels. METHODS: RT-PCR was used to demonstrate the expression of c-myc mRNA and immuno-chemistry strain was performed to detect the expression of PCNA protein in splenic veins of 28 patients with portal hypertension and 12 normal vessels. RESULTS: The straining of PCNA protein was (29.8 +/- 4.7)% in splenic veins with portal hypertension, Normal vessels did not detect PCNA protein expression (P < 0.01); RT-PCR showed that the expression of c-myc mRNA in PCNA-positive control and in negative control of splenic veins with portal hypertension were (7.61 +/- 1.04)% and (3.82 +/- 0.92)%, respectively. There ws different between two groups (P < 0.01) and significant different (P < 0.01) when compared with (1.01 +/- 0.21)% in normal vessels. CONCLUSIONS: The c-myc was immediate-early gene when it modulated proliferation of vascular smooth muscle cell. Hemodynamic disturbance of portal vein system activate the proto-oncogene of smooth muscle cells in splenic vein of patients with portal hypertension, promoting the proliferation, migrating and phenotypic change and resulting in vascular remodelling of splenic veins.

Adult↗