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Biomedical subjects

M Zhang

Publications and source records attributed to M Zhang.

At least 235 records · Page 13Linked to original sources
PubMed2001

Role of innate immune cells in protection against Toxoplasma gondii at inflamed site.

The intraperitoneal infection with Toxoplasma gondii (T. gondii) caused accumulation of gamma delta T, NK, NK1.1+T-like (NKT) cells at inflamed sites. To clarify the roles of these cells in protection against T. gondii at the inflamed sites, BALB/c mice were depleted of gamma delta T, NK, NK and NKT cells by treatment with antibody against TCR-gamma delta, asialoGM1 or Interleukin-2 receptor beta-chain (IL-2 R beta), respectively, prior to infection. Mice treated with anti-TCR-gamma delta monoclonal antibody (mAb) became more susceptible to infection, whereas mice treated with anti-IL-2R beta mAb acquired resistance. Treatment with anti-asialoGM1 Ab showed no effect. We previously reported that heat shock protein 65 (HSP65) in macrophages induced by gamma delta T cells plays an essential role in protective immunity against T. gondii infection, by preventing apoptotic death of infected macrophages. In the present study, we showed that treatment with anti-IL-2R beta mAb, but not with anti-asialoGM1 Ab, enhanced the HSP65 induction in macrophages, and inhibited Interleukin-4 (IL-4) expression in nonadherent peritoneal exudate cells. Furthermore, neutralization of endogenous IL-4 by anti-IL-4 mAb enhanced the HSP65 induction in macrophages. These findings suggest that NKT cells, but not NK cells, negatively regulate the protective immunity against T. gondii infection possibly by producing IL-4 and suppressing HSP65 induction.

Animals↗
PubMed2001

Differential regulation of interleukin-1 beta-induced cyclooxygenase-2 gene expression by nimesulide in human synovial fibroblasts.

Osteoarthritic (OA) human synovial fibroblasts (HSF) in culture were treated with the preferential COX-2 inhibitors nimesulide or NS-398, the non-specific COX-1/COX-2 inhibitor naproxen, or dexamethasone, in the presence or absence of IL-1 beta or LPS. Nimesulide or NS-398 inhibited IL-1 beta-induced PGE2 production at all concentrations tested, and in addition they suppressed IL-1 beta-induced COX-2 mRNA expression and protein synthesis. These suppressive effects were most evident at therapeutic levels of the drugs. Mechanistic studies revealed that the drug-induced inhibition of COX-2 expression and synthesis was not promoter-based, but may be associated with the blockade of IL-1 beta-dependent calcium flux and increased cellular calcium levels.

Arthritis, Rheumatoid↗
PubMed2001

[The establishment of four cell lines from Colossoma brachypomum and their growth characteristics under various temperatures].

Four cell lines originated from embryo, caudal fin, anal fin and snout of Colossoma brachypomum were established, and subcultured for 70, 47, 45 and 40 passages to the present. The results of the experiment indicated that the four cell lines were fibroblast-like diploid cells, and the model number of their chromosome is 54. These cell lines could grow under temperature of 20-35 degrees C, and its optimum temperature was 27-30 degrees C. The cells grew slowly at 20 degrees C, stopped growth at 15 degrees C, and died below 10 degrees C. This indicated that the growth temperature of the these cell lines was coincident with that of fish. In addition, the attachment time, doubling time, mitotic index, passage survival rate and cell cycle were determined and compared.

Animals↗
PubMed2001

The effect of IPN surface modification on the mechanical properties of UHMWPE.

This paper investigates the effect of IPN surface treatment on the mechanical properties of ultra high molecular weight polyethylene (UHMWPE). Traditional UHMWPE was modified by introducing poly-L-lysine (PLL) into their surface and forming a semi-interpenetrating network (IPN). Tensile, creep and fatigue tests were performed on these IPN and the control specimens. The tensile and creep results show that the IPN modification did plasticize the UHMWPE in that it decreased modulus and strength, increased ductility, and degraded creep resistance. However, these property changes are not so large as to be unacceptable. In the fatigue tests, there were no failures of control nor IPN samples up to 10 million cycles.

Coated Materials, Biocompatible↗
PubMed2001

[Expression of heme oxygenase-1 in neonatal rat cardiocytes induced by lipopolysaccharide].

To study the alterations of heme oxygenase-1 mRNA in neonatal rat cardiomyocytes (NRCMs) induced by lipopolysaccharide (LPS) and the role of heme oxygenase-1 (HO-1) in the LPS induced disorders of myocardium function, 10 (L, 6 h), 30 (M, 6 h), 50 micrograms/ml (H, 6 h) LPS and 10 micrograms/ml LPS + 10 mumol/ml Zn-protoporphyrin-IX (ZnPPIX; L + I, 6 h) and 10 mumol/ml ZnPPIX alone (I, 6 h) were added to the medium for a 6-hour culture of NRCMs, and 10 micrograms/ml LPS for 9 h (L, 9 h) and 18 h (L, 18 h) cultures. LDH release and MDA contents of the cells were measured. When NRCMs were collected, Trypan blue stain method was used to examine the mortality (the rate of Trypan blue uptake) of NRCMs. HO-1 mRNA expression was examined by Northern blot. The results showed that HO-1 mRNA expression of NRCMs increased gradually along with the increase of LPS concentration below the level of 30 micrograms/ml. When the final concentrations of LPS were 10 and 30 micrograms/ml, the HO-1 mRNA expression of NRCMs increased by 81.2% and 126.3% respectively compared with control. When the final concentration of LPS was 50 micrograms/ml, the HO-1 mRNA expression decreased to the level of 10 micrograms/ml group. When the final concentration was 10 micrograms/ml, the HO-1 mRNA expression increased gradually along with the culture time. After a 9- or 18-hour culture, the HO-1 mRNA expression of NRCMs increased by 93.6% and 105.8% respectively compared with control. Only when NRCMs had been cultured with 30, 50 micrograms/ml LPS and 10 micrograms/ml LPS + 10 mumol/ml ZnPPIX for 6 h and 10 micrograms/ml LPS for 18 h, the rate of Trypan blue stain uptake, MDA contents and LDH release significantly increased. With 10 micrograms/ml LPS alone and 10 mumol/ml ZnPPIX alone for 6 h, the above parameters were not significantly increased (P > 0.05). The results demonstrate that LPS induces HO-1 mRNA expression of NRCMs dose- and time-dependently to some extent. The inducible HO can protect NRCMs from injury and thus play an important role in pathogenesis of myocardium under LPS.

Animals↗
PubMed2001

Effects of parathyroid hormone on bone formation in a rat model for chronic alcohol abuse.

BACKGROUND: Alcoholism is a risk factor for osteoporosis and it is not clear whether the detrimental effects of alcohol on bone are reversible. Parathyroid hormone (PTH) is a potent stimulator of bone matrix synthesis and is being investigated as a therapeutic agent to reverse bone loss. The present investigation was designed to determine the effects of PTH on bone formation in a rat model for chronic alcohol abuse. METHODS AND RESULTS: Alcohol was administered in the diet of female rats (35% caloric intake) for 2 weeks. Human (1-34) PTH (80 microg/kg/day) was administered subcutaneously during the second week of the study. Alcohol resulted in a transient reduction in steady-state mRNA levels for the bone matrix proteins type 1 collagen, osteocalcin, and osteonectin compared with rats that were fed an alcohol-free (control) diet. As expected, alcohol decreased and PTH increased histologic indices of bone formation. Additionally, two-way ANOVA demonstrated that alcohol antagonized PTH-induced bone formation. Despite antagonism, bone formation and mRNA levels for bone matrix proteins in alcohol-fed rats treated with PTH greatly exceeded the values in rats fed the control diet. CONCLUSIONS: The results of this study contribute to a growing body of evidence that alcohol-induced bone loss is primarily due to reduced bone formation. We conclude that alcohol does not prevent the stimulatory effects of PTH on bone formation. This is evidence that the effects of alcohol on the skeleton are reversible. Additionally, the positive effects on bone formation in rats that consumed high concentrations of alcohol suggested that PTH may be useful as an intervention to treat alcohol-induced osteoporosis.

Alcoholism↗
PubMed2001

Predictors of virological response in HIV-infected patients to salvage antiretroviral therapy that includes nelfinavir.

Different salvage strategies have been used to regain control in patients with HIV who have virological failure on combination antiretroviral therapy. We conducted a cohort study of 63 extensively antiretroviral pretreated patients who initiated nelfinavir as part of salvage therapy, to determine predictors of virological response. The maximum HIV RNA response was >0.5 log10 copies/ml reduction in 43 patients (68%), including 21 patients (33%) who had suppression to <500 copies/ml. Corresponding response rates at 24 weeks were 41 and 19%, respectively. Responders and non-responders could not be distinguished by mean baseline HIV RNA or CD4 cell count, duration of prior protease inhibitor (PI) use, introduction of an initial non-nucleoside reverse transcriptase inhibitor or the number of antiretroviral agents changed when nelfinavir was added, likely reflecting the homogeneity of the population studied. The only parameter predictive of response was virus genotype. Response rates were lower in patients with increasing numbers of primary (P=0.045) or secondary (P=0.001) PI mutations. The addition of increasing numbers of reverse transcriptase mutations further impaired response rates (P=0.004).

Adult↗
PubMed2001

[Application of dhfr gene negative Chinese hamster ovary cell line to express hepatitis B virus surface antigen].

OBJECTIVE: To set up an efficient expressing system for recombinant hepatitis B virus surface antigen (HBsAg) in dhfr gene negative CHO cell line. METHODS: HBsAg gene expressing plasmid pCI-dhfr-S was constructed by integrating HBsAg gene into plasmid pCI which carries dhfr gene. The HBsAg expressing cell line was set up by transfection of plasmid pCI-dhfr-S into dhfr gene negative CHO cell line in the way of lipofectin. RESULTS: Under the selective pressure of MTX, 18 of 28 clonized cell lines expressed HBsAg, 4 of them reached a high titer of 1:32 and protein content 1-3 micrograms/ml. CONCLUSION: In this study, the high level expression of HBsAg demonstrated that the dhfr negative mammalian cell line when recombined with plasmid harboring the corresponding deleted gene can efficiently express the foreign gene. The further steps toward building optimum conditions of the expressing system and the increase of expressed product are under study.

Animals↗
PubMed2001

[3D visualization and information interaction in biomedical applications].

3D visualization and virtual reality are important trend in the development of modern science and technology, and as well in the studies on biomedical engineering. This paper presents a computer procedure developed for 3D visualization in biomedical applications. The biomedical models are constructed in slice sequences based on polygon cells and information interaction is realized on the basis of OpenGL selection mode in particular consideration of the specialties in this field such as irregularity in geometry and complexity in material etc. The software developed has functions of 3D model construction and visualization, real-time modeling transformation, information interaction and so on. It could serve as useful platform for 3D visualization in biomedical engineering research.

Biomedical Engineering↗
PubMed2001

Effect of tetramethyl pyrazine on L-type calcium channel in rat ventricular myocytes.

To elucidate possible ionic mechanisms of antimyocardial ischemia and antiarrythmia of tetramethyl pyrazine (TP), we studied L-type Ca2+ currents (I(Ca.L)) in adult rat ventricular myocytes using the whole-cell patch-clamp technique. The results showed: (i) under physiological conditions, 0.25 mmol/L TP decreased amplitude of I(Ca.L) to 60.6% and this inhibition was increased with increasing concentration of TP. ID50 was 0.20 mmol/L. (ii) The Ca2+-antagonistic effect of TP was voltage-dependent. A marked negative shift of the steady-state inactivation curve was observed with long (10 s) conditioning prepulses, but not with short (350 ms) ones. (iii) The time course of inhibition during TP treatment was increased with an increase in drug concentration, and recovery from TP-induced inactivation of I(Ca.L) was slower than in control cases. (iv) Tonic block and use-dependent block with TP treatment, which was induced by increasing the frequency of stimulation, occurred. We suggest that TP inhibits the I(Ca.L) mainly by binding to inactivated Ca2+ channels. The high affinity of TP for the inactivated state of I(Ca.L) may play an important role in developing therapies for pathological conditions.

Animals↗
PubMed2001

[Effect of Xue Zhi Kang on the formation of fatty liver in cholesterol-fed rabbits].

OBJECTIVE: To explore the effect of Xue Zhi Kang (XZhK) on the formation of fatty liver in cholesterol-fed rabbits. METHODS: XZhK was refined from Chinese traditional medicine Hong Qu and its main composition is HMG-CoA reductase inhibitor. Thirty New Zealand white rabbits were randomly assigned into 3 groups (control, hypercholesterol-fed, and XZhK groups) during the 12 week's experiment. The effects of XZhK (0.8g.kg(-1).d(-1)) were investigated in rabbits fed a l.5% cholesterol diet. The changes of serum TC, TG, HDL-C, and LDL-C concentrations and the histopathological changes of the liver were detected. RESULTS: The serum TC, LDL-C, and TG levels decreased in XZhK group compared with those in the cholesterol-fed control group (P<0.05 ). The serum HDL-C concentration slightly increased, but there was no statistical significance. The fatty degeneration of liver was ameliorated in XZhK group (P<0.05). CONCLUSIONS: XZhK can modulate the lipid metabolism and inhibit the formation of fatty liver in cholesterol-fed rabbits.

Animals↗
PubMed2001

[Determination of podophyllotoxin lignans in Dysosma and its allied plants].

The existence of podophyllotoxin lignans in Dysosma versipellis and its allied plants was analyzed by twice developing TLC, and the content by chromotropic-colorimetric assay. The results showed that podophyllotoxin lignans exist in the rhizoma, radix, stem and leaf of Dysosma versipellis and its allied plants. The total lignans content is 2%-7%, and there is a big variation between different species. The total lignans content of Dysosma versipellis is related to the habitat.

Berberidaceae↗
PubMed2001

Antifibrotic effects of matrine on in vitro and in vivo models of liver fibrosis in rats.

AIM: To study the antifibrotic effects of matrine in vitro a nd in vivo. METHODS: Rat hepatic stellate cell HSC-T6 and mouse fibroblast cell NIH3T3 proliferation stimulated with serum and platelet-derived growth factor (PDGF) was measured b y crystal violet staining assay. Collagen synthesis stimulated with serum and transforming growth factor beta1 (TGF-beta1) was determined by [3H]proline incorporation. Liver fibrosis was induced by carbon tetrachloride (CCl4) in rats an d evaluated with plasma hyaluranic acid level and hepatic hydroxyproline content. RESULTS: Matrine (1-2 mmol/L) markedly reduced serum-driven proliferation and collagen synthesis of HSC-T6 cells as well as NIH3T3 cells. PDGF-driven proliferative activity and TGF-beta1-driven collagen synthesis in HSC-T6 cel ls were attenuated by matrine (0.25-2 mmol/L) in a concentration-dependent manner. In vivo matrine (50 mg/kg and 100 mg/kg) significantly decreased serum hyaluranic acid levels and hepatic hydroxyproline contents in rats treated with CCl4. CONCLUSION: Inhibition of PDGF and TGF-beta1 actions on hepatic stellate cell by matrine might provide a possible mechanism of its antifibrotic activities.

3T3 Cells↗
PubMed2001

Matrine inhibits production and actions of fibrogenic cytokines released by mouse peritoneal macrophages.

AIM: To study the effects of matrine (Mat) on production and actions of fibrogenic cytokines from mouse peritoneal macrophages. METHODS: Mouse peritoneal macrophages were primed with calcimycin 1 micromol/L for 8 h then elicited by lipopolysaccharides (LPS) 100 microg/L for 6 h to induce fibrogenic cytokines. Proliferative and collagen stimulating activity in the macrophage culture supernatants was determined by crystal violet staining assay and [3H]-proline incorporation assay using rat hepatic stellate HSC-T6 cell or mouse fibroblast NIH3T3 cell. Transforming growth factor beta (TGFbeta) activity was measured by [3H]-thymidine incorporation assay using Mv-1-Lu mink lung epithelial cell. RESULTS: Mat (0.5-2 mmol/L) was shown to significantly inhibit LPS-induced collagen stimulating activities and TGFbeta production (P < 0.01) whereas did not inhibit proliferative activities induced by macrophages. Macrophage conditioned medium (MCM)-driven proliferation and collagen synthesis of HSC-T6 cells as well as NIH3T3 cells were attenuated by Mat (0.5-2 mmol/L) in a concentration-dependent manner. CONCLUSION: Antifibrotic effects of Mat on hepatic stellate cells may be related to reduction of fibrogenic cytokine production and blockade of their actions.

Alkaloids↗
PubMed2001

Effect of genistein and quercetin on proliferation, collagen synthesis, and type I procollagen mRNA levels of rat hepatic stellate cells.

AIM: To study the effects of genistein (GE) and quercetin (QU) on proliferation, collagen synthesis, and procollagen messenger RNA (mRNA) expression of rat hepatic stellate cell line HSC-T6 cells. METHODS: Cell proliferation was measured by crystal violet staining assay. Collagen synthesis was determined by [3H]proline incorporation assay. Type I mRNA level was determined by reverse transcription polymerase chain reaction (RT-PCR). RESULTS: GE (25 - 70 micromol/L) and QU (6.25 - 50 micromol/L) concentration-dependently reduced serum-driven HSC-T6 cell proliferation and collagen synthesis associated with a suppression of type I procollagen mRNA level. CONCLUSION: GE and QU inhibited hepatic stellate cell proliferation and collagen synthesis that might have a protective role against liver fibrosis.

Cell Division↗
PubMed2001

[Telomerase activity in cervical cancer and its precursor lesion].

OBJECTIVE: To study telomerase activity in cervical cancer and it's precursor lesion. METHODS: Thirty-six cervical cancer and 16 cervical intraepithelial neoplasia (CIN) specimens were measured for telomerase activity using TRAP-ELISA, and 11 normal cervix, 6 chronic cervicitis and 8 adjacent normal tissue specimens as controls. RESULTS: Mean telomerase activity in CIN, cervical cancer, and controls were 0.398 +/- 0.293, 1.580 +/- 0.819, 0.050 +/- 0.012. There was statistically significant difference among three groups (P < 0.01). Additionally, between patients with lymph node metastases (N+) and patients with tumor-free lymph nodes metastases (N-) a statistically distinct difference in telomerase activity was detected (P < 0.05). Telomerase activity was increasing with the advancing of histologic differentiated grade in invasive cervical cancer. However, no significant relationship was found between telomerase activity and tumor size, clinical stage, histology. CONCLUSIONS: Our data suggest that the reactivation of telomerase is an early event and may play an important role during cervical carcinogenesis and progression. It may be used as a tumor biomarker, helpful for the diagnosis of cervical cancer and CIN.

Adult↗