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Biomedical subjects

D Zhang

Publications and source records attributed to D Zhang.

At least 109 records · Page 6Linked to original sources
PubMed2001

Human platelets express gangliosides with LKE activity and ABH blood group activity.

BACKGROUND: Platelets express several neutral glycosphingolipids with ABH and P blood group activity that may play a role in infectious, autoimmune, and alloimmune thrombocytopenia. In RBCs, sialylated glycosphingolipids or gangliosides with blood group activity have also been reported. To determine whether similar antigens are expressed by platelets, the total platelet ganglioside fraction was isolated and screened for blood-group-active glycosphingolipids. STUDY DESIGN AND METHODS: Platelet gangliosides were isolated by organic extraction, base hydrolysis, anion exchange, silicic acid, and high-performance liquid chromatography. Gangliosides were identified and characterized by high-performance thin-layer chromatography-immunostaining with blood group-specific MoAbs and glycosidase digestion. RESULTS: Group A, but not group O, platelets express five gangliosides with group A activity. Of five A MoAbs and lectins examined, only MoAbs Birma-1 and MHO4 recognized all five sialyl A bands. The sialyl A bands were sensitive to endoglycoceramidase and neuraminidase. One sialyl A band may represent a branched ganglioside with sialyl-I and group A activity. Platelets also express an LKE-active ganglioside consistent with sialyl-galactosylgloboside. CONCLUSION: In addition to sialyl-iI and sialyl-Le(x) gangliosides, group A platelets express gangliosides with LKE activity and group A activity. Like RBCs, group A-active gangliosides may act as alloantigens and autoantigens to naturally occurring isohemagglutinins.

ABO Blood-Group System↗
PubMed2001

A molecular marker that is specific to medicinal rhubarb based on chloroplast trnL/trnF sequences.

"Da-Huang" (Radix et Rhizoma Rhei, medicinal rhubarb), a famous and important Traditional Chinese Medicine, has often been confused with the adulterant species in the same genus, Rheum. Through sequencing the trnL (UAA)/trnF (GAA) regions of chloroplast DNA of thirteen species of Rheum (three medicinal rhubarb species and ten adulterant ones), a molecular marker of the medicinal species was found. A pair of PCR primers based on the sequences, was thus designed, which amplified a highly specific DNA fragment in medicinal rhubarb exclusively, and absent in the adulterants at all under an optimized PCR condition.

Base Sequence↗
PubMed2001

Oxidation of phenothiazine and phenoxazine by Cunninghamella elegans.

1. To determine the ability of fungi to metabolize sulphur- and oxygen-containing azaarenes, Cunninghamella elegans ATCC 9245 was grown in 125-ml flasks containing fluid Sabouraud medium. The cultures and controls were incubated at 28 degrees C with shaking and dosed with 16.7 mM phenothiazine or phenoxazine. After incubation for 72h, the mycelia and filtrates were extracted with ethyl acetate and the combined residues analysed by high-performance liquid chromatography. Residual phenothiazine and phenoxazine were 21 and 22%, respectively, of the total UV absorbance at 254 nm. 2. The metabolites were identified by mass spectrometry and proton nuclear magnetic resonance spectroscopy. The fungus oxidized phenothiazine to phenothiazine sulphoxide, 3-hydroxyphenothiazine sulphoxide, phenothiazin-3-one, and 3-hydroxyphenothiazine and oxidized phenoxazine to phenoxazin-3-one. 3. Three of the four compounds produced by C. elegans from phenothiazine were identical to those produced by mammals, supporting the use of the fungus as a microbial model for drug metabolism.

Chromatography, High Pressure Liquid↗
PubMed2001

The anaerobic treatment of nitrite containing wastewater using an expanded granular sludge bed (EGSB) reactor.

The integration of denitrification from nitrite with methanogenesis was studied in this work. Experimental results from the continuous treatment of wastewater containing nitrite, which lasted for 144 days, demonstrated that wastewater containing nitrite could be anaerobically treated in an expanded granular sludge bed (EGSB) reactor. From 92% to 97% of COD was removed at organic COD volumetric loading rates up to 6.5 g COD l(-1) d(-1). Nitrite was denitrified for 97% to 100% at nitrite volumetric loading rates up to 0.9 g NO2-N l(-1) d(-1). Batch tests of 15 days with sludge from the reactor showed that 100% of nitrite and 93 to 95% of COD were removed. Nitrite was denitrified for 92 to 96% to N2. The remaining nitrite might be converted to NO and N2O. The ratio of COD to NO2--N for the denitrification was varied from 2.49 to 5.64. Denitrification from nitrite preceded methanogenesis. Methanogenesis recovered rapidly after the denitrification from nitrite was completed. No dissimilatory reduction of nitrite to ammonium occurred. Some small losses of ammonium could not be accounted for in the process.

Bacteria, Anaerobic↗
PubMed2001

Linear mixed models with flexible distributions of random effects for longitudinal data.

Normality of random effects is a routine assumption for the linear mixed model, but it may be unrealistic, obscuring important features of among-individual variation. We relax this assumption by approximating the random effects density by the seminonparameteric (SNP) representation of Gallant and Nychka (1987, Econometrics 55, 363-390), which includes normality as a special case and provides flexibility in capturing a broad range of nonnormal behavior, controlled by a user-chosen tuning parameter. An advantage is that the marginal likelihood may be expressed in closed form, so inference may be carried out using standard optimization techniques. We demonstrate that standard information criteria may be used to choose the tuning parameter and detect departures from normality, and we illustrate the approach via simulation and using longitudinal data from the Framingham study.

Biometry↗
PubMed2001

Acoustic nonlinearity parameter tomography for biological tissues via parametric array from a circular piston source--theoretical analysis and computer simulations.

The acoustic nonlinearity parameter B/A describes the nonlinear features of a medium and may become a novel parameter for ultrasonic tissue characterization. This paper presents a theoretical analysis for acoustic nonlinear parameter tomography via a parametric array. As two primary waves of different frequencies are radiated simultaneously from a circular piston source, a secondary wave at the difference frequency is generated due to the nonlinear interaction of the primary waves. The axial and radial distributions of sound pressure amplitude for the generated difference frequency wave in the near field are calculated by a superposition of Gaussian beams. The calculated results indicated that the difference frequency component of the parametric array grows linearly with distance from the piston source. It therefore provides a better source to do the acoustic nonlinearity parameter tomography because the fundamental and second harmonic signals both have a near field that goes through many oscillations due to diffraction. By using a finite-amplitude insert substitution method and a filtered convolution algorithm, a computer simulation for B/A tomography from the calculated sound pressure of the difference frequency wave is studied. For biological tissues, the sound attenuation is considered and compensated in the image reconstruction. Nonlinear parameter computed tomography (CT) images for several biological sample models are obtained with quite good quality in this study.

Journal Article↗
PubMed2001

Regulation of B(2)-kinin receptors by glucose in vascular smooth muscle cells.

The development of vascular disease is accelerated in hyperglycemic states. Vascular injury plays a pivotal role in the progression of atherosclerotic vascular disease in diabetes, which is characterized by increased vascular smooth muscle cell (VSMC) proliferation and extracellular matrix accumulation. We previously reported that diabetes alters the activity of the kallikrein-kinin system and results in the upregulation of kinin receptors in the vessel wall. To determine whether glucose can directly influence the regulation of kinin receptors, the independent effect of high glucose (25 mM) on B(2)-kinin receptors (B2KR) in VSMC was examined. A threefold increase in B2KR protein levels and a 40% increase in B2KR surface receptors were observed after treatment with high glucose after 24 h. The mRNA levels of B2KR were also significantly increased by high glucose as early as 4 h later. To elucidate the cellular mechanisms by which glucose regulates B2KR, we examined the role of protein kinase C (PKC). High glucose increased total PKC activity and resulted in the translocation of conventional PKC isoforms (beta(1) and beta(2)), novel (epsilon), and atypical (zeta) PKC isoforms into the membrane. Inhibition of PKC activity prevented the increase in B2KR levels induced by ambient high glucose. These findings provide the first evidence that glucose regulates the expression of B(2) receptors in VSMC and provide a rationale to further study the interaction between glucose and kinins on the pathogenesis of atherosclerotic vascular disease in diabetes.

Animals↗
PubMed2001

Hemodynamic effects of lipids in humans.

Evidence suggests lipid abnormalities may contribute to elevated blood pressure, increased vascular resistance, and reduced arterial compliance among insulin-resistant subjects. In a study of 11 normal volunteers undergoing 4-h-long infusions of Intralipid and heparin to raise plasma nonesterified fatty acids (NEFAs), we observed increases of blood pressure. In contrast, blood pressure did not change in these same volunteers during a 4-h infusion of saline and heparin. To better characterize the hemodynamic responses to Intralipid and heparin, another group of 21 individuals, including both lean and obese volunteers, was studied after 3 wk on a controlled diet with 180 mmol sodium/day. Two and four hours after starting the infusions, plasma NEFAs increased by 134 and 111% in those receiving Intralipid and heparin, P < 0.01, whereas plasma NEFAs did not change in the first group of normal volunteers who received saline and heparin. The hemodynamic changes in lean and obese subjects in the second study were similar, and the results were combined. The infusion of Intralipid and heparin induced a significant increase in systolic (13.5 +/- 2.1 mmHg) and diastolic (8.0 +/- 1.5 mmHg) blood pressure as well as heart rate (9.4 +/- 1.4 beats/min). Small and large artery compliance decreased, and systemic vascular resistance rose. These data raise the possibility that lipid abnormalities associated with insulin resistance contribute to the elevated blood pressure and heart rate as well as the reduced vascular compliance observed in subjects with the cardiovascular risk factor cluster.

Adult↗
PubMed2001

Simvastatin has anti-inflammatory and antiatherosclerotic activities independent of plasma cholesterol lowering.

Inhibitors of 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase, such as simvastatin, lower circulating cholesterol levels and prevent myocardial infarction. Several studies have shown an unexpected effect of HMG-CoA reductase inhibitors on inflammation. Here, we confirm that simvastatin is anti-inflammatory by using a classic model of inflammation: carrageenan-induced foot pad edema. Simvastatin administered orally to mice 1 hour before carrageenan injection significantly reduced the extent of edema. Simvastatin was comparable to indomethacin in this model. To determine whether the anti-inflammatory activity of simvastatin might affect atherogenesis, simvastatin was tested in mice deficient in apoE. Mice were dosed daily for 6 weeks with simvastatin (100 mg/kg body wt). Simvastatin did not alter plasma lipids. Atherosclerosis was quantified through the measurement of aortic cholesterol content. Aortas from control mice (n=20) contained 56+/-4 nmol total cholesterol/mg wet wt tissue, 38+/-2 nmol free cholesterol/mg, and 17+/-2 nmol cholesteryl ester/mg. Simvastatin (n=22) significantly (P<0.02) decreased these 3 parameters by 23%, 19%, and 34%, respectively. Histology of the atherosclerotic lesions showed that simvastatin did not dramatically alter lesion morphology. These data support the hypothesis that simvastatin has antiatherosclerotic activity beyond its plasma cholesterol-lowering activity.

Administration, Oral↗
PubMed2001

Signaling events mediating the additive effects of oleic acid and angiotensin II on vascular smooth muscle cell migration.

Obese hypertensive patients with cardiovascular risk factor clustering and increased risk for atherosclerotic disease have increased plasma nonesterified fatty acid levels, including oleic acid (OA), and a more active renin-angiotensin-aldosterone system. Vascular smooth muscle cell (VSMC) migration and proliferation participate in the development of atherosclerotic plaque. OA and angiotensin (Ang) II induce synergistic mitogenic responses in VSMCs through sequential signaling pathways dependent on the activation of protein kinase C (PKC), oxidants (reactive oxygen species, ROS), and extracellular signal-regulated kinase (ERK) activation. We tested the hypotheses that (1) OA and Ang II have additive or synergistic effects on VSMC migration and (2) PKC, ROS, and mitogen-activated protein kinase are critical signaling molecules. OA at 100 micromol/L increases VSMC migration 60+/-10% over control (P:<0.001). Ang II (10(-)(9) mol/L) increases VSMC migration by 62+/-13% and 73% over control, respectively (P:<0.01). Coincubation of cells with OA and Ang II produces a nearly additive increase in VSMC cell migration at 107+/-20% (P:<0.01). Increases in VSMC migration induced by OA alone and combined with Ang II were reduced by PKC inhibition and downregulation. VSMC migration in response to OA alone and with Ang II was also inhibited by N:-acetyl-cysteine, MEK inhibition, and ERK antisense. VSMC migration in response to OA alone or combined with Ang II is dependent on activation of PKC, ROS, and ERK activation, further raising the possibility that increased plasma nonesterified fatty acids and an activated renin-angiotensin-aldosterone system in subjects with the risk factor cluster contribute to accelerated atherosclerosis through a PKC, ROS, and ERK-dependent signaling pathway.

Acetylcysteine↗
PubMed2001

Lipids stimulate the production of 6-keto-prostaglandin f(1alpha) in human dorsal hand veins.

Obese hypertensives have increased nonesterified fatty acids (NEFAs) and alpha-adrenergic vascular reactivity. Raising NEFAs locally with intralipid and heparin augments dorsal hand venoconstrictor responses to phenylephrine, an alpha(1)-adrenoceptor agonist. The enhanced venoconstrictor responses were reversed by indomethacin. The findings suggest that raising NEFAs leads to the generation of cyclooxygenase (COX) product(s) that enhance vascular reactivity. To test this notion, 6-keto-PGF(1alpha) and TxB(2), the stable metabolites of prostaglandin H(2) (PGH(2)); prostacyclin (PGI(2)); and thromboxane (TxA(2)), were measured approximately 1.5 to 2 cm downstream of a dorsal hand vein infusion of intralipid and heparin (n=10) or saline and heparin (n=5) for 2 hours each. During the third hour, intralipid and heparin (experimental) and saline and heparin (control) were continued, and either saline (control) or indomethacin (intervention) were infused. Intralipid and heparin raised local 6-keto PGF(1alpha) concentrations by 350% to 500% (P<0.005), but saline and heparin did not (P=NS). TxB(2) levels did not change significantly with any infusion. Infusion of indomethacin during the third hour of intralipid and heparin lowered plasma 6-keto-PGF(1alpha) (P<0.05), whereas infusion of saline with intralipid and heparin did not (P=NS). Oleic and linoleic acids at 100 micromol/L, increased 6-keto-PGF(1alpha) in vascular smooth muscle cells (VSMCs) through a protein kinase C and extracellular, signal-regulated kinase independent pathway. However, oleic and linoleic acids increased intracellular Ca(2+) in VSMCs. The data indicate that NEFAs induce the production of COX products, perhaps via Ca(2+)-dependent activation of phospholipase A(2). The COX product(s) may contribute to increased vascular alpha-adrenergic reactivity among insulin-resistant individuals when NEFAs are elevated.

6-Ketoprostaglandin F1 alpha↗
PubMed2001

One-year study of felodipine or placebo for stage 1 isolated systolic hypertension.

Asubstantial number of older hypertensive patients have stage 1 isolated systolic hypertension (systolic blood pressure between 140 and 159 mm Hg and diastolic blood pressure <90 mm Hg), but there are currently no data showing that drug treatment is effective, safe, and/or beneficial. To compare the effects of active treatment compared with placebo on blood pressure, left ventricular hypertrophy, and quality of life among older stage 1 isolated systolic hypertensive patients, a randomized, double-blind, parallel-group, multicenter clinical trial comparing felodipine (2.5, 5, or 10 mg once daily) and matching placebo was performed in 171 patients (49% male, average age 66+/-7 years, with 49% white and 30% Hispanic) with a baseline blood pressure of 149+/-7/83+/-6 mm Hg. During 52 weeks of treatment, patients randomized to active treatment achieved significantly lower blood pressures (137.0+/-11.7/80.2+/-7.6 mm Hg for extended-release felodipine versus 147.5+/-16.0/83.5+/-9.7 mm Hg for placebo, P<0.01 for each), a reduced incidence of left ventricular hypertrophy (7% for extended release felodipine versus 24% for placebo, P<0.04), and improved quality of life (change in Psychological General Well-Being index, 3.0+/-6.8 for extended-release felodipine versus -0.8+/-10.3 for placebo, P<0.01) versus baseline. There were no clinically significant differences between treatments in tolerability or adverse effects. Stage 1 isolated systolic hypertension can be effectively and safely treated pharmacologically. Treatment reduced progression to the higher stages of hypertension, reduced the incidence of left ventricular hypertrophy, and improved an overall measure of the quality of life. Larger and longer studies will be needed to document any long-term reduction in cardiovascular event rates associated with treating stage 1 systolic hypertension.

Aged↗
PubMed2001

The effect of Bcl-2 adenovirus against murine hepatocyte apoptosis caused by tumor necrosis factor alpha and D-galactosamine.

OBJECTIVE: To evaluate the role of Bcl-2 family proteins in hepatic apoptosis caused by TNF-alpha and D-galactosamine. METHODS: We induced mouse liver injury with TNF-alpha and D-galactosamine, and detected hepatic apoptosis, the expression of Bcl-2, Bax, and Bak proteins on hepatocytes by using TUNEL or immunohistochemistry, respectively. We also observed the expression of Bcl-2 protein on hepatocytes infected with Bcl-2 adenovirus vector and its protection against hepatocyte apoptosis. RESULTS: Hepatocyte apoptosis was induced in BalB/c mice pretreated with TNF-alpha plus D-galactosamine, accompanying the enhanced expression of Bax, Bak proteins in hepatocytes. Bcl-2 protein was expressed in murine hepatocytes and lasted at least 1 month after injection of Bcl-2 adenovirus vector, which also lowered ALT level from (1372.9+/-251.4)U/L to (796.5+/-78.7)U/L and reduced hepatocyte apoptosis caused by TNF-alpha and D-galactosamine. CONCLUSIONS: The enhanced expression of Bax, Bak proteins may play a role in hepatocyte apoptosis induced by TNF-alpha and D-galactosamine. D-galactosamine adenovirus vector can partially reduced hepatocyte apoptosis induced by TNF- alpha and D-galactosamine.

Adenoviridae↗
PubMed2001

Development and application of the serological assay for humoral immune response against duck hepatitis B virus.

OBJECTIVE: To develop a simple and specific assay for detection of humoral immune response in duck hepatitis B virus (DHBV) infected ducks. METHODS: Eighty serum samples were detected by ELISA for DHBsAg with prepared anti-preS 1H1 ascitic fluid and by PCR or dot blot hybridization for DHBV DNA. Thirty-two serum samples from experimentally infected 1-day-old ducks were assayed by ELISA for DHBcAb and DHBsAb. RESULTS: Of 66 PCR positive samples, 58 were positive for DHBsAg and 62 were positive for DHBV dot blot hybridization. Sensitivities of the two methods were 87.9% and 93.9%, respectively. Anti-DHBc was developed in 2/8 infected ducks at day 21 but negative after day 28. Anti-DHBs antibodies were negative throughout the infectious period. CONCLUSION: The application of DHBV infection and serological assay will be helpful to the study of kinetics of DHBV and humoral immune response of ducks against the virus.

Animals↗
PubMed2001

Hepatitis B virus transgenic mice for the model of anti-hepatitis B virus drug study.

OBJECTIVE: To establish hepatitis B virus (HBV) transgenic mice models and to investigate if the model can be used for the evaluation of anti-HBV drugs. METHODS: HBV transgenic mice models were produced by microinjection to analyze the integration, expression of HBV in the transgenic mice by nested PCR, southern blot, immunohistochemistry, and ELISA. Sixty mice whose HBV DNA, HBsAg were positive were divided into 6 groups randomly, in which 3 groups were given drugs: lamivudine administrated by perfusion of stomach tube (100mg x kg(-1) x day(-1) for 21 days); thymosine administrated by abdomen injection (3mg x day(-1) for 90 days); and DNA vaccine of 100 microg by muscle injection. The other 3 groups were negative control. RESULTS: Lamivudine, thymosine and DNA vaccine made HBV DNA become negative in the serum of HBV transgenic mice. The negative ratio was highest in lamivudine treatment group. HBV DNA became positive again when lamivudine terminated. CONCLUSION: Limvudine, thymosine, and DNA vaccine can inhibit HBV replication. Transgenic mice might be used as the model for anti-HBV drug screening and evaluation.

Animals↗
PubMed2001

[Study on the awareness, treatment and control of hypertension in Qingdao rural residents].

In order to study the awareness, treatment and control rates and the risk factors of hypertension in Qingdao rural residents, a cluster random sampling method was used. Blood pressure measurement and questionnaire regarding risk factors for hypertension were applied to 3700 residents aged over 18. The standardized prevalence of hypertension in selected Qingdao rural residents was 19.5%. The awareness rate of hypertension was 31.5%. The main factors affecting awareness included age, cultural level, family income, family history of hypertension, and knowing the criteria for normal blood pressure (BP). The rate of taking regular treatment for hypertension was 35.7%. The factors affecting treatment for hypertension were age, culture level, times of measuring blood pressure (BP), suffering from complications of hypertension and family income. The awareness, treatment and control of hypertension should be improved and a comprehensive measure should be taken to prevent hypertension in Qingdao rural residents.

Adult↗
PubMed2001

[Recombinant human growth hormone downregulates the apoptosis of HepG(2) cells induced by LPS].

OBJECTIVE: To investigate the effect of LPS on human hepatocytes and study whether recombinant human growth hormone (rhGH) could protect hepatocytes from apoptosis induced by LPS. METHODS: HepG(2) cells were treated with LPS (20 microg/ml) or LPS and rhGH for 16 hours. The apoptosis of HepG(2) cells was detected by terminal deoxynucleotide transferase-mediated dUTP nick end labeling (TUNEL) or electron microscopy. RESULTS: HepG(2) cells treated with LPS exhibited some specific morphological features of typical apoptosis. the percentage of apoptotic cells in HepG(2) cells treated with LPS and hrGH was significantly lower than that treated with LPS (36+/-5.6)% vs (99+/-0.8)%, P<0.001). CONCLUSIONS: LPS can induce apoptosis of HepG(2) cells, and hrGH can downregulate the apoptotic role of LPS on HepG(2) cells.

Apoptosis↗