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Biomedical subjects

G Z Liu

Publications and source records attributed to G Z Liu.

At least 19 recordsLinked to original sources
PubMed2001

Nitric oxide mediates the change of proteoglycan synthesis in the human lumbar intervertebral disc in response to hydrostatic pressure.

STUDY DESIGN: This in vitro study clarifies the role of nitric oxide (NO) in human lumbar intervertebral disc metabolism. OBJECTIVE: To investigate the effects of NO on proteoglycan synthesis in human lumbar discs and to test the hypothesis that NO is a mediator of the changes in proteoglycan synthesis in response to hydrostatic pressure. SUMMARY OF BACKGROUND DATA: The authors have clarified that hydrostatic pressure has an apparent effect on proteoglycan synthesis as well as matrix metalloproteinase production in the intervertebral disc. The cellular mechanisms underlying the response of disc cells to hydrostatic pressure remain to be clarified. Herniated lumbar discs produce NO in response to interleukin (IL)-1 beta. In articular cartilage, NO mediates the change of proteoglycan synthesis by IL-1 or shear stress. METHODS: Fifty-eight lumbar intervertebral disc specimens were obtained from patients who had undergone posterior discectomy. The specimens were chopped into 1-2-mm cubes and were incubated in a plastic syringe with 1 mL Dulbecco's modified Eagle's medium (DMEM). The syringes were placed in a water-filled pressure vessel kept at 37 C. Hydrostatic pressures of 1 (control), 3, and 30 atmospheres (atm) were applied. Proteoglycan synthesis was determined from (35)S-sulfate incorporation rates. Nitrite (the stable oxidation product of NO) concentration in DMEM was determined by a spectrophotometric method based on the Griess reaction. As a competitive inhibitor of NO synthases, N(G)-methyl-l-arginine (l-NMA, 10-1000 micromol) and as an organic donor of NO, S-nitroso-N-acetylpenicillamine (SNAP, 1-200 micromol) were used. RESULTS: Addition of l-NMA suppressed NO production and increased proteoglycan synthesis rates in the intervertebral disc specimens in a dose-dependent fashion. Addition of SNAP increased exogenous NO content in the medium significantly and suppressed proteoglycan synthesis rates in a dose-dependent fashion. Three-atmosphere hydrostatic pressure stimulated the proteoglycan synthesis rates. Rates were approximately 1.3-fold greater than at 1 atm, whereas 30-atm pressure inhibited proteoglycan synthesis rates. However, the hydrostaticpressure had inverse effect on NO production. At 3 atm, NO production decreased slightly relative to 1 atm, whereas at a pressure of 30 atm, NO production was increased and was approximately 1.32-fold greater than at 1 atm. L-NMA enhanced the 3-atm pressure-induced increase in proteoglycan synthesis and also relieved the suppression of proteoglycan synthesis at a pressure of 30 atm. CONCLUSION: The current study confirmed the previous finding that human herniated lumbar disc cultures spontaneously produce NO. Endogenously generated and exogenously supplied NO inhibited proteoglycan synthesis in the intervertebral disc. Hydrostatic pressure influenced NO production by disc cells, and NO is one of the mediators that changes proteoglycan synthesis in response to hydrostatic pressure. These results may show that autocrine and paracrine mechanisms of NO play an important role in the regulation of disc cell metabolism under mechanical stress and in the pathophysiology of intervertebral disc degeneration.

Adolescent↗
PubMed2001

The effect of antihypertensive treatment on cardiovascular events--a meta-analysis of four clinical trials in China.

OBJECTIVE: The pooled results of four large-scale clinical trials of antihypertensive treatments carried out in China were assessed, with an overall study population of 10,457 patients. METHODS: The fixed effect model was used for data analysis. RESULTS: A pooled analysis at the individual level showed that the average time of treatment was 3.4 years, after which an average reduction in blood pressure of 9/4 mmHg was found. The meta-analysis showed that stroke was reduced by 36% (95% CI 25%-46%, P < 0.001), cardiovascular death and total deaths were reduced by 22% and 20% respectively (P < 0.05) and total cardiovascular events were significantly reduced by 33% (P < 0.001). However, the reduction in coronary heart disease (CHD) was much smaller and was not statistically significant (P > 0.05), whereas the significant reduction in stroke was epidemiologically expected. CONCLUSION: The benefit of antihypertensive treatment obtained was mostly due to a reduction in the incidence of stroke.

Antihypertensive Agents↗
PubMed2001

[A PC-based pulse oximetry monitor for four patients].

Pulse oximeters are used in many departments of a hospital. The pc-based pulse oximetry monitor for many patients has the features of simplicity, flexibility, large memory, powerful function, high ratio of performance to price, and it is easy to communicate with multimonitors. The principles of hardware system and the function of software block of the monitor are introduced too in this paper.

Equipment Design↗
PubMed2000

[Studies of transgenic tobacco plants expressing beta-1,3-glucanase and chitinase genes and their potential for fungal resistance].

Plant bivalent expression vector pBLGC for basic tobacco beta-1, 3-glucanase and bean chitinase genes were constructed, and the tobacco tissue was transformed. Transgenic tobacco plants were carried out for analysis by PCR, PCR-Southern blot, Dot blot, Western blot, etc., and the results showed that some transgenic plants gave strong positive signal, it suggested that foreign genes have been integrated into tobacco genome, and expressed correctly. Fungal challenge with Alternaria alternata showed that transgenic plants were much more resistant to this pathogenic fungus.

Chitinases↗
PubMed2000

[Studies on transgenic oilseed rape (Brassica napus) plants transformed with beta-1,3-glucanase and chitinase genes and its resistance to Sclerotinia sclerotiorium].

By Agrobacterium-mediated method, the cotyledonary petiole of good quality rape variety H165 was transformed with plant expression vector pBLGC which constitutively express beta-1,3-glucanase and chitinase genes. We obtained some Kanamycin(Kan)-resistant regenerational green shoots, with these shoots, PCR identification was conducted. Results showed that 30% green shoots which grew in medium of Kan 15 mg/L and 53% green shoots in Kan 25 mg/L had positive reaction. We also made dot blot analysis with those green shoots, some of them gave positive signal, indicating that the foreign genes had integrated into rape genome. Fungal challenge of these transgenic plants showed that some plants were much more resistant to Sclerotinia sclerotiorium than non-transgenic control plants.

Ascomycota↗
PubMed2000

Tripterygium wilfordii saponins and interleukin-10 prevent induction of experimental autoimmune thyroiditis by dendritic cells.

AIM: To study the roles of Tripterygium wilfordii saponins (TII) and interleukin-10 (IL-10) on dendritic cells (DC)-induced experimental autoimmune thyroiditis (EAT). METHODS: We used mice as autoimmune thyroiditis model animals and divided them into 4 groups, namely DC group, TII group, IL-10 group, and control group. The level of thyroglobulin (Tg) antibody was assayed by ELISA. TNF beta production in the cultured supernatants and nitric oxide (NO) in the serum were measured by biological activation assay and Griess reaction, respectively. Tg-stimulated proliferation of lymphocytes was detected with MTT incorporation assay. The histopathological analysis of thyroid was carried out. RESULTS: Tg-pulsed DC were able to induce EAT with increase in the concentration of TgAb in serum and lymphocytes infiltration in thyroid. After treatment with TII or IL-10, DC could not induce EAT with lower levels of TgAb and no lymphocyte infiltration. The concentration of NO in serum, TNF beta activation, and the proliferation of lymphocytes in response to thyroglobulin in TII or IL-10 group were lower than those in DC group. CONCLUSION: TII and IL-10 are able to strongly inhibit the ability of DC to induce experimental autoimmune thyroiditis.

Animals↗
PubMed2000

[Purification of soluble egg antigen (SEA) 38 kDa molecule of Schistosoma japonicum and preliminary evaluation of its immunodiagnostic efficacy].

OBJECTIVE: To study the applicability of soluble egg antigen (SEA) 38 kDa molecule of Schistosoma japonicum in the immunodiagnosis of schistosomiasis. METHODS: The target immunodiagnositic antigen SEA 38 kDa molecule was separated and purified by SDS-PAGE and electroelution technique and evaluated by SDS-PAGE and Western blotting. To compare their immunodiagnostic efficacy, the purified SEA 38 kDa and SEA were used to examine the sera from 182 cases including 31 acute schistosomiasis patients, 31 chronic schistosomiasis patients, 60 normal human controls, 30 paragonimiasis patients and 30 clonorchiasis patients. RESULTS: The positive rates of purified SEA 38 kDa and SEA for acute schistosomiasis patients, chronic schistosomiasis patients, normal human controls, paragonimiasis patients and clonorchiasis patients were 90.3%, 90.3%, 1.7%, 0, 0 and 90.3%, 83.9%, 3.3%, 0, 0, respectively. The P/N ratio of purified SEA 38 kDa and SEA in immunodiagnosis of schistosomiasis by ELISA had been compared by two-sample t-test. It was demonstrated that there existed significant differences between purified SEA 38 kDa and SEA in the three groups of acute and chronic schistosomiasis patients and normal persons(P < 0.001). The P/N ratio of SEA 38 kDa in detecting the sera from schistosomiasis patients was obviously higher than that of SEA, but when SEA 38 kDa was used to examine normal human sera, the result was converse. CONCLUSION: The purified SEA 38 kDa has higher sensitivity and specificity and immunodiagnostic potential.

Animals↗
PubMed1999

Genetoxicity of water samples from the scenic Lijang river in the Guilin area, China, evaluated by Tradescantia bioassays.

The Lijang river which passes through the Guilin mountains, and Guilin city is a world renowned scenic spot on the southwest border of China. The river and its tributaries receive water from the mountain tops and springs underground. The river water was clean two decades ago before the development of industrial establishments and extra heavy tourism. Deforestation over the mountain tops on the upper stream and its tributaries in the last decades has created serious erosion and increased sedimentation in the river. In the present study, the Tradescantia micronucleus (Trad-MCN) and Tradescantia stamen hair mutation (Trad-SHM) assays were used to evaluate the genetoxicity of water samples collected from 60 different sites along the river. Results indicate that most of the water samples from the tributaries were highly mutagenic, and that pollutants had accumulated in the main river in the Guilin city area from the industrial effluent and city sewage. Both the Trad-MCN and Trad-SHM assays were highly effective for the detection of mutagens in the water samples.

Biological Assay↗
PubMed1999

Baculovirus expression of the major surface antigen of Toxoplasma gondii and the immune response of mice injected with the recombinant P30.

The major surface antigen (P30) of the Toxoplasma gondii was expressed by an insect cell culture system infected with recombinant baculovirus. About 750 microg of purified (95% purity) P30 was obtained from a culture of 10(8) insect Sf21 cells. The recombinant P30 was used to immunize mice to induce immune response. Mice injected with the recombinant protein produced specific humoral and cellular immune responses. Immunization with P30 also prolonged the period of survival of mice infected by Toxoplasma. The average survival time of control group is 13.25+/-1.16 days, but are 16.13+/-2.1 days, 19.50+/-3.21 days, 20.38+/-3.38 days in different immunized groups, respectively.

Animals↗
PubMed1997

Protection by capsaicin against attenuated endothelium-dependent vasorelaxation due to lysophosphatidylcholine.

Previous studies have shown that pretreatment with calcitonin gene-related peptide (CGRP), a principal transmitter in sensory nerves, can protect the endothelial cell. We therefore evaluated whether in vivo capsaicin treatment prevents endothelial damage elicited by lysophosphatidylcholine (LPC) in the rat aorta. Acute treatment or repeated pretreatment with capsaicin resulted in stimulation of neurotransmitter release from sensory nerves or depletion of their transmitter content respectively. Vasodilator responses to acetylcholine (ACh) were examined in the aorta of these animals. Acute application of capsaicin (50 mg/kg) increased the plasma concentration of CGRP-like immunoreactivity (CGRP-LI) concomitantly with a reversal of the inhibition by LPC of endothelium-dependent ACh-induced relaxation in the isolated rat aorta. After repeated pretreatment with capsaicin to deplete sensory nerve neurotransmitter content the effects of capsaicin were absent as shown by the plasma CGRP-LI concentration and the vasodilator response to ACh. The results demonstrate that systemic capsaicin treatment, which evokes the release of CGRP from sensory nerves, protects the endothelial cell. The present study also suggests that CGRP may be an endogenous vascular protective substance.

Acetylcholine↗
PubMed1996

Endogenous inhibitors of nitric oxide synthesis and lipid peroxidation in hyperlipidemic rabbits.

AIM: To examine whether the elevation of endogenous NG, NG-dimethylarginine (DMA) content is related to lipid peroxidation in the high lipid-fed rabbit. METHODS: In high lipid diet-fed rabbits, concentrations of serum cholesterol, triglyceride, malondialdehyde (MDA), and DMA were measured, and endothelium-dependent relaxation to acetylcholine (ACh) was tested. RESULTS: After 6-wk on a high lipid-diet, the levels of serum total cholesterol, triglyceride, MDA, and DMA were increased vs those in control group (MDA was 2.88 +/- s 0.20 vs 1.54 +/- 0.13 nmol.L-1, P < 0.01 and DMA was 1.51 +/- 0.07 vs 0.75 +/- 0.13 mumol.L-1, P < 0.01), while the endothelium-dependent vasodilation in the isolated thoracic aorta was impaired (the maximal response to ACh was 45.59 +/- 3.10 vs 76.93 +/- 5.68%). Supplementation with vitamin E decreased MDA and DMA content and improved the endothelium-dependent vasodilation. CONCLUSIONS: An increase in serum concentration of DMA may be secondary to the elevation of lipid peroxides in the hyperlipidemic rabbit.

Animals↗
PubMed1994

Effect of electrochemical therapy on immune functions of normal and tumour-bearing mice.

The effect of electrochemical therapy (ECT) on immune functions of normal and tumour-bearing mice was studied. In normal mice, ECT had no obvious effect on delayed type hypersensitivity (DTH) or on the mononuclear phagocytic system, but significantly reduced the production of agglutinin antibodies. In tumour-bearing mice, ECT enhanced the DTH reaction, increased the production of agglutinin antibodies and enhanced the clearance of Congo red. In conclusion, in tumour-bearing mice, ECT enhanced both cellular immune functions of T- and B-lymphocytes and non-specific immune functions of the phagocytic system.

Animals↗
PubMed1994

[Functional and histological evidence of insulin resistance in spontaneously hypertensive rat].

In order to confirm the existence of insulin resistance in spontaneously hypertensive rat (SHR), rich musculature glucose tolerance test (GTT) and histological method examination of the insulin receptor were carried out in SHR and the normotensives (WKY). The basal serum insulin level was higher and the area under insulin curve during GTT was also higher in SHR than those in WKY, while the basal serum glucose level and the area under glucose curve during GTT in SHR were similar to those in WKY. As compared with WKY, SHR displayed a significantly lower percentage of insulin sensitive slow-twitch fiber of plantaris and medial head of gastrocnemius (type I fiber). There were strong positive correlations between blood pressure (BP) and insulin as well as between BP and the area under insulin curve, but the correlation between insulin and percentage of type I fiber was negative. In conclusion, the present study provides both functional and structural evidence of insulin resistance in SHR.

Animals↗