PubMed Health⌕ Search

Biomedical subjects

Z Ding

Publications and source records attributed to Z Ding.

At least 109 records · Page 6Linked to original sources
PubMed1995

[A morphological study of experimental corneal neovascularization].

Corneal neovascularization (CNV) was induced by alkali burn injuries in 20 rabbit corneas. The process of CNV was observed with biomicroscopy in vivo and histologically by light and electron microscopy. At 8 hours after injury, an obvious acute inflammatory response as evidenced by infiltration of neutrophils had already occurred in the pericorneal limbal area. Many neutrophils in the extravascular space contained abundant intracytoplasmic phagolysosomes. The vascular sprouts appeared 2 days after injury. The infiltration of neutrophils and their debris were visible around newly formed blood vessels in the cornea. The results suggest that there be the participation and an inductive action of neutrophils in the pathogenesis of CNV.

Animals↗
PubMed1995

[Adhesion of erythrocytes of patients with cerebral thrombosis to injured endothelial cells].

Using flow chamber system, we quantitatively studied the adhesion of erythrocytes (RBCs) of patients with cerebral thrombosis (CTh) to cultured human umbilical vein endothelial cells (HUVECs) treated with H2O2. The results showed that injured HUVECs enhanced adhesion of RBCs to HUVECs in patients with CTh. There is injury of endothelial cells in the pathogenetic and pathologic process of CTh, and the adhesion of RBCs to ECs promotes vaso-occlusive and vascular damage; thus the adhesion of RBCs to injured ECs might play an important role in the pathogenesis and pathologic process of CTh.

Aged↗
PubMed1995

[Step increase in shear stress effects on releasing prostacyclin of human umbilical vein endothelial cell].

Adopting the flow chamber, we studied the effect of step increase in shear stress on prostacyclin releasing of human umbilical vein endothelial cell (HUVEC). HUVEC monolayer was exposed to step increase in shear stress levels of 1, 10 and 20 dyne/cm2 for 100 minutes. By radioimmunoassay, 6-keto-PGF1 alpha in flowing out liquid from the flow chamber was measured. The results displayed: when HUVEC was not exposed to shear stress, the PGI2 released from HUVEC was not detectable; when HUVEC was exposed to shear stress, the flow onset led to an initial burst increase of PGI2 production rate, which went down subsequently within several minutes. We noticed that the larger the step increase of shear stress became, the higher the peak value of PGI2 production rate ascended, the quicker the peak value subsequently declined, and the higher the average value of PGI2 releasing rate in 80-100 minutes stood. The results demonstrated that in vivo hemorheological factor-the shear stress of blood flowing stimulated the release of prostacyclin from HUVEC.

Cells, Cultured↗
PubMed1995

[The effects of Salvia miltiorrhiza and polysaccharide sulphate on the adhesion of erythrocytes of the patients with cerebral thrombosis to cultured endothelial cells].

Salvia miltiorrhiza and polysaccharide sulphate are commonly prescribed for curing cerebral vascular diseases. In this study, we found that the adhesion of erythrocytes of the patients with cerebral thrombosis to cultured human umbilical vein endothelial cells was decreased in number and intensity after the erythrocytes were treated with salvia miltiorrhiza and polysaccharide sulphate in flow field. Moreover we found that polysaccharide sulphate was more effective than salvia miltiorrhiza in preventing adherence in common doses. The two drugs' effects of preventing adherence might be an important mechanism for curing the patients with cerebral thrombosis.

Aged↗
PubMed1994

Suppression by isoproterenol of endothelial cell morphology and barrier function changes induced by platelet-activating factor.

Using a model to study vascular permeability on hydrostatically perfused bovine pulmonary artery endothelial cell (EC) monolayers and software to analyze cell morphological parameters automatically in a computer image workstation, we studied the effects of isoproterenol (IPN) on platelet-activating factor (PAF)-induced changes in EC monolayer permeability and cell morphological parameters. Albumin has fortifying effects on endothelial barrier function. As albumin concentration in the perfusate increased (0, 1, 5, 10, 20 mg/ml), EC monolayer hydraulic conductivity (Lp) decreased gradually while Lp of the filter membranes did not change. After treatment of the EC monolayer with PAF 10(-8) mol/liter for 30 min, transmonolayer fluid flow, protein clearance rate, and Lp value increased noticeably. At the same time, cell area decreased and intercellular distance and percentage of intercellular space area in total cell monolayer increased. Pretreatment with 10(-4) mol/liter IPN blocked PAF-induced EC permeability and morphological changes, suggesting that EC contraction and intercellular gap formation are important mechanisms for PAF-induced high vascular permeability. IPN inhibits the effects of PAF via stabilization of EC morphology, protection of intercellular junction, and blockade of intercellular gap formation.

Albumins↗
PubMed1994

A molecular genetic survey indicates the presence of a single, homogeneous strain of Echinococcus granulosus in north-western China.

A combination of DNA methods, including conventional RFLP, PCR-RFLP and mitochondrial sequence analysis did not detect genomic variation in any of 117 E. granulosus isolates examined from a range of intermediate hosts, including humans, in north-western China. The genotype infecting all hosts was indistinguishable from the widespread and well recognised sheep strain of E. granulosus. The public health implication of the study is that most, if not all, livestock infected with E. granulosus in this region will act as reservoirs of human infection.

Animals↗
PubMed1994

Purification and properties of cow splenic biliverdin reductase.

Biliverdin reductase was purified from cow spleen. The specific activity of the final enzyme preparation was 24.01 u/mg, representing 686-fold purification as measured with NADPH. The yield was 3 grams of enzyme per 100 grams of cow spleen. The purified enzyme was a monomeric protein with an apparent molecular weight of about 34,000 and an isoelectric point of about 6.2. The biliverdin reductase was specific for biliverdin and reduced IX alpha faster than the biliverdin isomers IX beta, IXr, or IX delta. The purified enzyme could utilize both NADH and NADPH, but the kinetic properties of the NADH-dependent and the NADPH-dependent enzyme activities were different: the time course of the NADPH-dependent reaction displayed a sigmoidal curve, whereas that of the NADH-dependent reaction did not. Km for biliverdin IX alpha was 4 x 10(-4) mM in the NADPH system, while it was 1.5 x 10(-3) mM in the NADH system. Both enzyme activities were inhibited by excess biliverdin, but the inhibition of the NADPH-dependent enzyme activity was more pronounced. The pH optimum was 7.0 with NADH, and 6.8 with NADPH.

Animals↗
PubMed1994

Response of constrained and unconstrained bubbles to lithotripter shock wave pulses.

The Gilmore formulation for spherical bubble dynamics [F. R. Gilmore, The Growth or Collapse of a Spherical Bubble in a Viscous Compressible Liquid (California Institute of Technology, Pasadena, CA, 1952), Rep. No. 26-4] is used to investigate the response of air bubbles to a variety of lithotripter shock waveforms. A modification of the Gilmore model is proposed to account for partial constraint of the bubble expansion that can be caused by bubble coatings (such as in echo contrast agents) and by tissues or vessels surrounding bubbles in vivo. In the modified formulation, a viscoelastic membrane is assumed to exist at the bubble interface to include the possible effects of the nonlinear elasticity and strain rate dependent viscosity on the bubble response. The stress induced in the membrane is assumed to be an exponential function of the bubble radius, which tends to restrict the bubble expansion. The viscosity is assumed to increase with the strain rate. In the absence of the membrane, the maximum bubble wall pressure induced by a negative (tensile) pulse is much larger than that induced by a positive (compressive) pulse of the same pressure waveform and amplitude. This difference increases with decreasing initial bubble radius. The addition of the viscoelastic membrane significantly decreases the predicted maximum bubble pressure and the difference in response between the positive and negative pulses. The effect of the time delay between double pulses (positive followed by negative or negative followed by positive) is also investigated for unconstrained bubbles.

Humans↗
PubMed1993

Internal stress wave measurements in solids subjected to lithotripter pulses.

Semiconductor strain gauges were used to measure the internal strain along the axes of spherical and disk plaster specimens when subjected to lithotripter shock pulses. The pulses were produced by one of two lithotripters. The first source generates spherically diverging shock waves of peak pressure approximately 1 MPa at the surface of the specimen. For this source, the incident and first reflected pressure (P) waves in both sphere and disk specimens were identified. In addition, waves reflected by the disk circumference were found to contribute significantly to the strain fields along the disk axis. Experimental results compared favorably to a ray theory analysis of a spherically diverging shock wave striking either concretion. For the sphere, pressure contours for the incident P wave and caustic lines were determined theoretically for an incident spherical shock wave. These caustic lines indicate the location of the highest stresses within the sphere and therefore the areas where damage may occur. Results were also presented for a second source that uses an ellipsoidal reflector to generate a 30-MPa focused shock wave, more closely approximating the wave fields of a clinical extracorporeal lithotripter.

Acoustics↗
PubMed1993

Carbohydrate supplementation spares muscle glycogen during variable-intensity exercise.

Effects of carbohydrate (CHO) supplementation on muscle glycogen utilization and endurance were evaluated in seven well-trained male cyclists during continuous cycling exercise that varied between low [45% maximal O2 uptake (VO2 max)] and moderate intensity (75% VO2 max). During each exercise bout the subjects received either artificially flavored placebo (P), 10% liquid CHO supplement (L; 3 x 18 g CHO/h), or solid CHO supplement (S; 2 x 25 g CHO/h). Muscle biopsies were taken from vastus lateralis during P and L trials immediately before exercise and after first (124 min) and second set (190 min) of intervals. Subjects then rode to fatigue at 80% VO2 max. Plasma glucose and insulin responses during L treatment reached levels of 6.7 +/- 0.7 mM and 70.6 +/- 17.2 microU/ml, respectively, and were significantly greater than those of P treatment (4.4 +/- 0.1 mM and 17.7 +/- 1.6 microU/ml) throughout the exercise bout. Plasma glucose and insulin responses of S treatment were intermediate to those of L and P treatments. Times to fatigue for S (223.9 +/- 3.5 min) and L (233.4 +/- 7.5 min) treatments did not differ but were significantly greater than that of P treatment (202.4 +/- 9.8 min). After the first 190 min of exercise, muscle glycogen was significantly greater during L (79 +/- 3.5 mumol/g wet wt) than during P treatment (58.5 +/- 7.2 mumol/g wet wt). Furthermore, differences in muscle glycogen concentrations between L and P treatments after 190 min of exercise and in time to fatigue for these treatments were positively related (r = 0.76, P < 0.05). These results suggest that CHO supplementation can enhance prolonged continuous variable-intensity exercise by reducing dependency on muscle glycogen as a fuel source.

Adult↗
PubMed1992

Mechanisms of endothelial cell-dependent leukocyte adhesion stimulated by platelet-activating factor.

Platelet-activating factor (PAF) stimulates leukocyte-endothelial cell (EC) adhesion through its effects either on leukocytes or on ECs. ECs may be injured, synthesize, or express new adhesive proteins to increase leukocyte adhesion. Intermediary mediators produced by activated ECs are also likely involved in promoting leukocyte adhesion. Our experiments demonstrated that PAF induced no obvious damage to bovine pulmonary artery ECs evaluated by lactic dehydrogenase release rate, angiotensin-converting enzyme activity, and cellular malondialdehyde content. Treatment of EC monolayers with 10(-9) M PAF increased polymorphonuclear leukocyte (PMN) adhesion. Increasing PAF concentration did not induce more PMN adherence. PAF elicited both a rapid and prolonged increment of PMN adherence to EC monolayers. The rapid adherence was greatly attenuated by pretreatment of ECs with PAF receptor antagonist SRI 63-441 but was not affected by pretreatment of PMNs with SRI 63-441, suggesting that PAF increases PMN adherence rapidly through its effects on specific receptors on ECs. Increased PMN adherence lasted if PAF treatment of ECs was sustained for 3 or 6 h. Pretreatment of ECs with actinomycin D, a protein synthesis inhibitor, significantly decreased PAF-induced sustained PMN adherence, but the inhibition is incomplete, suggesting that other mechanisms than protein synthesis also participated in the prolonged PMN adherence. We concluded from the results that PAF may induce both rapid and prolonged PMN adhesion to ECs. The effects are receptor mediated. The prolonged PMN adhesion is partly the result of protein synthesis.

Animals↗
PubMed1992

[Exercise prescription for obese children].

Exercise prescription for obese children was formulated according to the characteristics of development of aerobic capacity of children of China and obese children as follows: intensity: 50% of VO2 duration: 1 hr/day, 12 weeks; frequency: 5 days per week; type of exercise: rhythmical and aerobic in nature such as running and various endurance game-type activity (football).

Child↗
PubMed1991

Hydatid disease in China.

Hydatid disease is one of the world's most geographically widespread zoonoses. It is present on all inhabited continents and occurs in tropical, subtropical, temperate, sub-arctic and arctic regions. The two countries with the greatest areas over which transmission occurs are almost certainly the Soviet Union and China. Until recently, however, very little information about hydatidosis in China was available outside the country(1). Since the 'open-door' policy over the past few years the great importance of hydatid disease in north and western China is gradually being realized.

Journal Article↗
PubMed1991

Inhibition of rat lens aldose reductase by quercetagetin and patuletin.

In this paper the results of inhibition of the Aldose reductase (AR) activity on Wistar rat lens by Quercetagetin extracted from Tagetes erects Linn and by Patuletin extracted from Tagetes patula Linn are reported. Quercetagetin inhibited AR of the rat lens by 93.9% at 10(-4) M, 76.0% at 10(-5) M and 13.3% at 10(-6) M. Patuletin inhibited AR of the rat lens by 100% at 10(-1) M, 80% at 10(-5) M and 22.7% at 10(-6) M respectively. The results show that these two flavones are lens AR Inhibitors, but further study should be done for the possibility of clinical application.

Aldehyde Reductase↗