Biomedical subjects

Chun Wang

Publications and source records attributed to Chun Wang.

45 records · Page 3Linked to original sources

PubMed2004

Comparison of unenhanced CT and chemical shift MRI in evaluating lipid-rich adrenal adenomas.

OBJECTIVE: Our aim was to evaluate adrenal adenomas in patients who underwent both unenhanced CT and chemical shift MRI to determine if adenomas can be characterized with MRI when the findings of CT are indeterminate. MATERIALS AND METHODS: Between January 1999 and June 2003, 40 patients (42 adrenal masses) underwent unenhanced CT and chemical shift MRI and were retrospectively analyzed. Hounsfield units, adrenal-to-spleen chemical shift ratio, and signal-intensity index were obtained for each adrenal mass. Qualitative analysis for loss of signal in each adrenal mass on the opposed-phase images was also performed by two reviewers and compared with the quantitative analyses. A lipid-rich adenoma was diagnosed if the mass measured equal to or less than 10 H, had an adrenal-to-spleen chemical shift ratio of less than 0.71, and had a signal-intensity index of greater than 16.5% or if the mass fulfilled two of the preceding criteria and had follow-up imaging without change. RESULTS: The sensitivities and specificities for diagnosing a lipid-rich adenoma using the qualitative, adrenal-to-spleen chemical shift ratio, signal-intensity index, and unenhanced CT attenuation analyses were 92% (33/36) and 17% (1/6), 100% (36/36) and 100% (6/6), 100% (36/36) and 67% (4/6), and 78% (28/36) and 83% (5/6), respectively. Twenty-eight (67%) lipid-rich adenomas measured equal to or less than 10 H, had an adrenal-to-spleen chemical shift ratio of less than 0.71, and had a signal-intensity index of greater than 16.5%. Eight masses (19%) measured greater than 10 H but had an adrenal-to-spleen chemical shift ratio of less than 0.71 and a signal-intensity index greater than 16.5% and were unchanged at follow-up. CONCLUSION: Eight (62%) of 13 adrenal adenomas measuring greater than 10 H on unenhanced CT were definitively characterized with chemical shift MRI.

Adenoma↗

PubMed2004

Motion sensitivity in cat's superior colliculus: contribution of different visual processing channels to response properties of collicular neurons.

It is well established that neurons in the retinorecipient layers of superior colliculus (SC), the mammalian homologue of the optic tectum of other vertebrates, are extremely sensitive to moving stimuli. In our studies we have distinguished several functionally distinct groups of neurons in the retinorecipient layers of the SC of the cat on the basis of their velocity response profiles. Our data revealed substantial convergence of the Y and non-Y information channels on single SC neurons. Second, using the method of selective conduction block of the Y-type fibers in one optic nerve we have shown that responses of SC cells to high-velocity motion are dependant on the integrity of Y-type input. Third, in order to determine the degree of influence of the X- and W-type input on cellular responses we have examined spatial and temporal frequency response profiles of single collicular neurons using sinusoidal gratings drifting in the preferred direction. At any given eccentricity, most collicular neurons exhibited a preference for relatively very low spatial frequencies. The preference for low spatial frequencies combined with temporal frequency profiles of collicular neurons suggests that the Y- and W-type inputs constitute the major functional inputs to the retinorecipient layers of the SC and that the "top-down" X-type input from the visual cortex has only a minor impact on the spatio-temporal frequency response profiles of collicular receptive fields.

Animals↗

PubMed2004

[Cell apoptosis in atrophic skeletal muscle induced by immoblization in rabbits--an experimental study using TUNEL].

This experiment was designed to explore the correlation between the mechanism of immobilization-induced skeletal muscle atrophy and the apoptosis of muscular cells. The models of skeletal muscle atrophy induced by immobilization for different length of time were established according to Sievanen II methods. 24 rabbits, each of them having one hind leg fixed by the tubal plaster and the other one free as control, were randomly divided into four groups depending on time of fixation (3, 7, 14, and 28 days respectively). The animals were sacrificed by the end of fixation. TdT-mediated d-UTP nick end labeling (TUNEL) was used to investigate the apoptotic muscle cells in the animal's bone. By comparing the apoptotic muscle cells with the morphology of the skeletal muscle, the correlation between cell apoptosis and skeletal muscle atrophy were analyzed. Apoptotic muscle cells did appear after immobilization in the atrophied skeletal muscle. In various groups, some cells with false positive stained TUNEL were found in the atrophic muscle, which could be distinguished from apoptotic cells by their characteristics. In conclusion, cell apoptosis participates in the process of skeletal muscle atrophy induced by immobilization; the amount of apoptotic cells is strongly associated with the time of immobilization, its peak appears on the 14th day of immobilization; the distribution of apoptotic skeletal muscle cell varies with the time of fixation. The severity of skeletal muscle atrophy is associated with the degree of the muscle cell apoptosis.

Animals↗

PubMed2003

[The relationship between insulin resistance and endothelium-dependent vasodilatation in obese subjects].

OBJECTIVE: To study the relationship between insulin resistance and endothelium-dependent vasodilatation function in obese subjects with normal blood glucose, serum cholesterol and blood pressure and to explore the non-traditional risk factors associated with atherosclerosis. METHODS: 24 euglycemic obese males (OB) and 12 age and sex matched lean controls (Lean) underwent oral glucose tolerance test (OGTT), euglycemic hyperinsulinemia clamp study with an insulin infusion rate of 120 mU/m(2)/min to evaluate the peripheral glucose disposal rate (GDR) in steady-state, brachial artery ultrasound study to assess the endothelium-dependent vasodilation (EDV) and independent vasodilation (EIV), the combined intima-media thickness (IMT) of common carotid arteries examined by high resolution ultrasound, and fasting lipids profile and free fatty acids (FFAs) concentration. RESULTS: The blood glucose and serum cholesterol levels were all normal in the OB group but the serum FFA and triglyceride concentrations were elevated compared with those of the controls (FFA: 888 microM/l +/- 158 microM/l vs 508 microM/l +/- 137 microM/l, P < 0.05; TG: 1.8 mM/l +/- 0.6 mM/l vs 1.1 mM/l +/- 0.5 mM/l, P < 0.05) The GDR in steady-state was 6.7 mg x min(-1) x kg(-1) +/- 1.4 mg x min(-1) x kg(-1) in the OB group, significantly lower than that of the controls (12.2 mg x min(-1) x kg(-1) +/- 3.1 mg x min(-1) x kg(-1), P < 0.05). In the OB group the flow-mediated dilation of the brachial artery caused by reactive hyperemia (EDV) were impaired and the relaxation time was shorter than that of the controls (P < 0.05) but the EIV was not significantly different between these two groups. There was a significantly positive correlation between GDR and EDV (r = 0.438, P < 0.05). The IMT of common carotid arteries was thicker in the OB group than in the control group (0.50 mm +/- 0.02 mm vs 0.34 mm +/- 0.19 mm). CONCLUSION: The endothelium-dependent vasodilation was impaired in obese subjects even though without hyperglycemia, hypercholesterolemia, and hypertension. Traditional cardiovascular risk factors cannot fully account for the increased risk of cardiovascular disease in metabolic syndrome. Elevated circulating FFA concentration, is characteristic of metabolic syndrome, may play a role in endothelial dysfunction.

Adult↗

PubMed2003

Rapid method for the determination of trace fluoride and activation of ion-selective electrode.

A method for activating ISE is proposed that can allow determination of the fluoride concentration at ng mL(-1) level with good precision and accuracy. Fluoride ISE is activated in 0.5 mol L(-1) HClO4 medium and then fluoride is determined in the same medium. The linear range for the determination of fluoride is between 1.00 x 10(-2)-1.00 x 10(-7) mol L(-1), and the detection limit of the method is 1.0 ng mL(-1). The advantage of this method is that it is free from the use of TISAB solution while being, time-saving and labor-saving. A mechanism study of the activation of FISE in HClO4 medium is explained. The method has been used for the determination of trace fluoride in milk and flour with satisfactory results.

Journal Article↗

PubMed2003

Allogeneic peripheral blood stem cell transplantation in the treatment of severe aplastic anemia and severe infection.

OBJECTIVE: To investigate the efficacy of allogeneic peripheral blood stem cell transplantation (PBSCT) in the treatment of severe aplastic anemia (SAA) and severe infection. METHODS: A patient with SAA and pseudomonas aeruginosa septicemia was treated with PBSCT from an HLA-identical sibling with cyclophosphamide (CY) and total body irradiation (TBI) for conditioning. The patient was infused with 20.3 x 10(8)/kg mononuclear cells including 61.0 x 10(6)/kg CD34(+) cells following the conditioning regimen. RESULTS: Twelve days after PBSCT, the absolute neutrophil count (ANC) of 1.0 x 10(9)/L was achieved, with platelet count > 50 x 10(9)/L at twenty days. The donor origin of engraftment was confirmed by polymerase chain reaction (PCR) analysis of short tandem repeats at the end of the first, sixth and twelfth month. The patient's body temperature dropped to normal level when her ANC reached 0.5 x 10(9)/L on day 10, and the bacterial culture of blood sample became negative subsequently. Symptoms and signs of acute or chronic graft versus host disease (GVHD) were not observed in 30 months after PBSCT. CONCLUSIONS: Hematopoiesis was reconstituted shortly after PBSCT. The combination of CY and TBI and the infusion of sufficient peripheral blood stem cells may contribute to the successful engraftment. PBSCT may be considered as the first choice when hematopoietic stem cell transplantation is needed for SAA patients complicated with severe infection.

Adult↗

PubMed2003

[Pioglitazone hydrochloride monotherapy or in combination with sulfonylurea therapy improves glycemia control in patients with type 2 diabetes].

OBJECTIVE: To evaluate the clinical efficacy and tolerability of pioglitazone monotherapy or in combination with sulfonylurea therapy in the treatment of chinese patients with type 2 diabetes. METHODS: This 12-week study involved 117 patients with type 2 diabetes whose blood glucose was uncontrolled on a stable regimen of diet or oral sulfonylureas for at least 3 months (fasting blood glucose (FBG) 7.8-15.0 mmol/L; postprandial blood glucose (PBG) >11.1 mmol/L)). The patients received once daily pioglitazone 30 mg plus diet (Group PIO-mono) or sulfonylurea (Group PIO-SU). The fasting and postprandial plasma glucose, serum insulin, C-peptid, lipid profile, free fatty acids (FFAs) levels were measured at baseline and every 4 weeks after treatment. Results All patients showed significant improvement in glycemic control over baseline. There were 1.64%, 2.1 mmol/L, 5.2 mmol/L decrease from baseline HbA1c, FBG and PBG levels in the Group PIO-mono and 1.06%, 2.3 mmol/L, 5.4 mmol/L decrease in the Group PIO-SU after 12 weeks treatment, respectivley. Both groups experienced slight decreases in C-peptide and insulin concentrations during 12 weeks period. Both groups showed mean percent decreases in triglyceride and FFA levels(21.8% and 20.7% for PIO-mono, 22.2% and 14.5 for PIO-SU) and increases in HDL-C (21.4% for PIO-mono and 30.8% for PIO-SU), compared with baseline. pioglitazone was well tolerated. CONCLUSION: In patients with type 2 diabetes, pioglitazone monotherapy or in combination with sulfonylurea therapy significantly improves HbA1c, FBG and PBG levels and reserves the beta-cell function with beneficial effects on serum triglyceride and HDL-C levels.

Adult↗

PubMed1998

Mutation of G138P Enhanced the Thermostability of D-glucose Isomerase.

In order to enhance the thermostability of D-glucose isomerase (GI), Gly 138 was decided to be the target to be replaced by molecular design. The mutant G138P was obtained by in vitro site-directed mutagenesis of GI gene. The recombinant plasmid pTKD-GI containing mutant site was expressed in E. coli K38 strain. The comparison experiments of GIG138P with wild-type GI showed that: (1) The half time of GIG138P was as about two times as that of the wild type. (2) The optimum temperature of GIG138P was increased by 10-12 degrees. (3) The specific-activity of GIG138P was similar to the wild-type GI. We supposed, based on the above facts, that the substitution of Pro for Gly at position 138 introduced a pyrrolidine ring, which could just fill perfectly the empty hole leaved by Gly-138 which has no side chain and could make the protein structure more rigid, therefore the mutant G138P enhanced the thermostability of SM33GI.

Journal Article↗

PubMed1996

Effects of Site-specific Mutagenesis of K253 and N184V on the Thermostability of D-Glucose Isomerase.

In order to enhance the thermostability of D-Glucose isomerase (GI), its mutants, GIK253R and GIN184V, were obtained with the double primer method of site-directed mutagenesis. Then their biochemical properties were assayed and compared with wild-type GI. The results showed that: (1) The mutant K253R was less stable than the wild-type GI at 70 degrees and 80 degrees. But in 1 M L-Rhaminose at 70 degrees, they had similar rate of heat inactivation. Furthermore, the mutant K253R has higher specific activity than the wild-type GI. (2) The mutant N184V had much less thermostability and specific activity as compared with the wild-type GI. These results were explained by their kinetic parameters and crystal structure model.

Journal Article↗