Biomedical subjects

Z Chen

Publications and source records attributed to Z Chen.

At least 289 records · Page 16Linked to original sources

PubMed2001

Growth inhibition of gastric cancer cells by all-trans retinoic acid through arresting cell cycle progression.

OBJECTIVE: To investigate the mechanism of all-trans retinoic acid (ATRA) on the regulation of the cell cycle in gastric cancer cells. METHODS: The protein level was detected by Western blot. Immunoprecipitation was used in protein kinase activity determination. Cell growth and cell cycle phase were examined by MTT assay and flow-cytometric analysis, respectively. RESULTS: ATRA could effectively induce G0/G1 arrest and inhibit cell growth in certain human gastric cancer cell lines. ATRA might induce p21WAF1/CIP1 expression in ATRA-sensitive cell lines through p53-dependent and p53-independent pathways. Induction of p21WAF1/CIP1 caused decrease in CDK4 and CDK2 activities independent of CDK4 and CDK2 protein expression levels. In addition, the dephosphorylated form of Rb protein increased because of the down-regulation of CDK4 and CDK2 activities by ATRA. CONCLUSIONS: Growth inhibition on gastric cancer cells by ATRA occurs through the regulation of relevant proteins leading to the arrest of cell cycle progression.

Antineoplastic Agents↗

PubMed2001

Erythrocyte membrane protein abnormalities in beta-thalassemia of the Li nationality in Hainan.

OBJECTIVE: To determine the composition of abnormal red cell membrane skeleton. METHODS: By sodium dodecyl sulphate polyacrylamide gel electrophoresis of ghostcorpuscles, we quantified the amount of protein by densitometric evaluation. RESULTS: The results showed that in beta-thalassemia, the amount of spectrin, 4.5 protein and globin significantly increased compared with the controls (26.05 +/- 1.46, 21.69 +/- 1.86; 22.87 +/- 5.61, 12.99 +/- 2.33; 15.23 +/- 3.31 and 4.97 +/- 2.73, respectively, P < 0.05). CONCLUSION: These data suggest that the erythrocyte membrane protein composition matched with globin in patients with beta-thalassemia of the racial Li minority are different from the normal control. These factors increase rigidity but decrease deformability of the beta-thalassemic red cell membrane, which may lead to hemolytic anemia.

China↗

PubMed2001

[Expression of extraneuronal monoamine transporter gene and DNA repair gene vis-à-vis with antitumor efficacy of SarCNU in human tumor xenografts].

OBJECTIVE: To clarify if there are any correlations between extraneuronal monoamine transmitters (EMT), DNA repair gene expressions and SarCNU antitumor efficacy. METHODS: EMT, DNA repair gene O6-methylguanine-DNA methyltransferase (MGMT) and excision repair cross-complementing rodent repair deficiency gene (ERCC1-6) expressions in 9 human xenograft tumor models were determined by RT-PCR. The results were compared with the antitumor effects of SarCNU on these tumor xenografts. RESULTS: Multiple regression analysis revealed significant correlations of SarCNU antitumor activity with different combinations of gene expression. The most significant correlation was observed with all of the 4 genes expressed. CONCLUSION: The results suggest that expression of both EMT and DNA repair genes, specifically, MGMT, ERCC2 and ERCC4, are important determinants of SarCNU activity against human tumors. While DNA repair decreases SarCNU's activity by repairing damaged DNA, EMT appears to enhance its antitumor efficacy.

Animals↗

PubMed2001

[Piezoelectric ceramic--a novel material for bone replacement].

Based on the piezoelectric effect of nature bone, the biocompatibility of a piezoelectric ceramic and bone tissue is observed and studied in four aspects: cytocompatibility, tissue-compatibility, mechanical compatibility and electro-compatibility. The results show that the piezoelectric ceramic is biocompatible. It is not harmful to the morphology and proliferation of L929. There is osteal combination between the piezoelectric ceramic and bone. Its mechanical properties are also suitable for bone replacement. Especially, it can induce the growth of osseous tissues along the chosen direction according to the piezoelectric properties of bone. It is envisaged that the piezoelectric ceramic may be developed and used as a novel material for bone replacement.

Animals↗

PubMed2001

[Applications of sol-gel method in preparation of biomaterials].

In recent years, there has been a great development in the applications of sol-gel method in preparation of biomaterials. In this article, the sol-gel process and its use in preparation of biomaterials are reviewed, and the authors also introduce their studies to be done. Finally, the future development trend are forecasted.

Biocompatible Materials↗

PubMed2001

Gene polymorphism in IL-1 receptor antagonist affects its production by monocytes in IgA nephropathy and Henoch-Schonlein nephritis.

OBJECTIVE: To define the functional significance of IL-1 receptor antagonist (IL-1ra) gene polymorphism and to investigate, the production of IL-1ra by monocytes from individuals with different genotypes of IL-1. METHODS: The genotype of IL-1ra was detected by polymerase chain reaction (PCR). Peripheral monocytes obtained from patients with immunoglobin A nephropathy (IgAN), Henoch-Schonlein purpura nephritis (HSPN) and normal subjects were matched in sex and age between the IL1RN-2 allele carriers and non-carriers. The secretion of IL-1ra, IL-1 alpha and IL-1 beta in the supernatant of GM-CSF (10 ng/ml) treated and untreated monocytes were measured by ELISA. RESULTS: The secretion of IL-1ra by monocytes stimulated with GM-CSF was significantly higher in the IL1RN-2 allele non-carriers than those of carriers both in IgAN (21.55 +/- 3.08 vs 13.85 +/- 2.24 ng/ml, P < 0.001) and HSPN (23.72 +/- 6.68 vs 12.67 +/- 2.24 ng/ml, P < 0.01) as well as in normal controls (20.29 +/- 1.45 vs 10.51 +/- 2.3 ng/ml, P < 0.001). All showed no significant differences in monocyte secretion of IL-1 alpha and IL-1 beta by GM-CSF stimulation between the IL1RN-2 allele carriers and non-carriers. CONCLUSIONS: These results indicate that a functional correlation of the IL1RN-2 allele and IL-1ra production is present in patients with IgAN and HSPN. This gene polymorphism control of IL-1ra production may contribute to the variety of clinical responses to inflammatory stimulation in individuals with different genotype of IL-1ra.

DNA↗

PubMed2001

[The application of laser therapy plus endobronchial stenting in treatment of complete airway obstruction].

OBJECTIVE: To assess the efficacy of laser therapy plus endobronchial stenting in the treatment of complete airway obstruction. METHODS: 17 cases with complete airway obstruction were treated with Nd: YAG laser and endobronchial stenting from April 1998 to November 2000. The patients' dyspnea, airway gauge, pulmonary function and complications were observed. RESULTS: The airways were all restructured following a single or multiple laser treatment; the airway gauge enlarged and the average diameter increased (5.82 +/- 1.01) mm. Immediate relief of dyspnea was achieved in sixteen patients and dyspnea index lessened one grade in 4 patients, 2 grades in 11 and 3 grades in one. Obvious improvement of forced expiratory volume in one second (FEV(1)) was noted in all patients;the improvement averaged (0.49 +/- 0.18) L. Endobronchial stents were placed for 14 patients after laser treatment. After stent placement, the airway was further opened and the average airway gauge increased (3.50 +/- 0.94) mm further in diameter. Patients' dyspnea and FEV(1) were further improved; dyspnea index lowered one grade in eight patients and 2 grades in two patients. FEV(1) improved further (0.41 +/- 0.20) L in average. Complications after laser therapy included hypoxemia in 15 patients, hemorrhage in 2 and postoperative dyspnea in 3. Follow-up duration ranged from 2-20 months. Complications after stenting included recurrent pneumonia in 4 patients, airway obstruction due to granuloma or tumour growth in 5 and stent migration in 1. CONCLUSION: Laser therapy and endobronchial stent placement were effective in the treatment of patients with totally occluded airway. Nd: YAG laser can be first chosen to restructure the occluded airway, then endobronchial stent must be used to further enlarge the airway and maintain the therapeutic effect.

Adolescent↗

PubMed2001

[Effects of radiofrequency catheter ablation in coagulation system].

OBJECTIVE: To investigate the pathogenesis and prophylactic therapy of peripheral vascular embolism after radiofrequency catheter ablation (RFCA). METHOD: 90 patients with supraventricular tachycardia (SVT) were divided into 3 groups. Group A did not use any anticoagulant before RFCA and group B used aspirin (ASA) before RFCA, group C used calcium channel blocker-amlodipine before RFCA. Blood samples were taken at 4 time points, i.e. before and after electrophysiologic examination, immediately after RFCA and 2 days after RFCA. For each blood example, blood levels of platelet alpha-granule membrane glycoprotein-140 (Gmp-140), thromboxane B(2) (TXB(2)), protein C (PC), protein S (PS) were measured. RESULT: In group A, Gmp-140 and TXB(2) of the blood examples taken before electrophysiologic examination were significantly lower than those taken at the three other time points, but there was no significant change of PC and PS as compared with that at the three other time points. Ablation either on the left or right heart did not affect the levels of Gmp-140 and TXB(2); In group B and group C, the levels of Gmp-140 and TXB(2) of the samples were significantly lower than those of the corresponding points in group A. CONCLUSION: It is indicated that platelet aggregability may be introduced by RFCA, but evolution of the anticoagulant system was not caused by RFCA, This may enhance the occurrence of thrombosis. ASA and amlodipine may prevent the occurrence of thrombosis.

Adolescent↗

PubMed2001

[Observations of properties of the L-form of M. tuberculosis induced by the antituberculosis drugs].

OBJECTIVES: To investigate the mechanism of generation of L-form of M. tuberculosis and its significance on the development, diagnosis and treatment of tuberculosis. METHODS: M. tuberculosis was inoculated into the non-high osmotic medium with rifampin, isoniazid or ethambutol and then the L-form was observed by microscopy daily. The cultures were filtrated to get the pure cultures of stable L-form by subculture with the non-high osmotic medium and characteristics of morphology, growth, susceptibilities to the antibacterial drugs and the special gene of M. tuberculosis were observed when the pure subcultures of the L-form were isolated. RESULTS: L-form of M. tuberculosis was induced by the concentrations of routine inhibition test of rifampin, isoniazid or ethambutol. The L-form would not be susceptible to the above mentioned antituberculosis drugs but susceptible to streptomycin, erythromycin, ofloxacin, norfloxacin and others. The morphologies of L-form were irregular or spherical with single, paired or chain form, and growth under the bottom of the medium but not movement or adhere to the glass. The L-form was negative by acid-fast stain and negative or positive by Gram stain. The gene of L-form reacted with the PCR kit for the M. tuberculosis and showed the same band. CONCLUSIONS: M. tuberculosis could be killed by rifampin, isoniazid or ethambutol but also could be induced to become the L-form by these antituberculosis drugs, and it is one of the important factor that affecting the effect of treatment of the tuberculosis. The cell wall deficient variants of M. tuberculosis could be determined by the PCR of M. tuberculosis. It is recommended that the L-forms should be noticed during the treatment with the antituberculosis drugs and combination treatment with antituberculous drugs to which the L-forms were susceptible, is also very important.

Antitubercular Agents↗

PubMed2001

[Experimental study for lung fluid transport by epithelial cells and aquaporins].

OBJECTIVE: To explore the effects of aquaporins (AQP) 1, 4 on water transport between airspace and pulmonary capillary and high pressure pulmonary edema. The other purpose was to study the active alveolar fluid transport as well as alveolar fluid clearance (AFC) in different pH of airspace. METHODS: The effects of AQP1, 4 on water transport between airspace and pulmonary capillary and high pressure pulmonary edema were studied by surface fluorescence methods and gravimetric method respectively, AFC and AFC in airspace with different pH were measured by isotope method. RESULTS: AQP1 knockout inhibited water transport through pulmonary capillary and also reduced high pressure pulmonary edema. Salbutamol increased AFC, but it was reduced when propranolol was used together. AFC was improved by terbutaline, isoproterenol, salmeterol when pH > 2.5 in airspace, but the effect was reduced after pH < 2.5 in airspace. Sodium channel inhibitor, Benzamil, could also inhibit AFC. CONCLUSIONS: AQP1 knockout significantly reduced water transport through alveolar capillary, and also reduced high pulmonary edema slightly. beta adrenergic stimulant improved AFC in mechanically ventilated rats. Intact airspace is very important for the function of AFC, however, the effect of AFC was impaired after lung injury induced by pH < 2.5 in airspace.

Animals↗

PubMed2001

A metaschema of the UMLS based on a partition of its semantic network.

The Unified Medical Language System's (UMLS's) Semantic Network (SN) provides an important conceptual abstraction that helps orient users to the vast knowledge content of its Metathesaurus. However, the SN is itself large and complex, and can also benefit from an additional abstract view of its own. In this paper, we present a metaschema that serves such a purpose. This metaschema is derived from a previously developed partitioning methodology for the SN. The metaschema is formally defined, and used to provide partial compact views of the SN.

Semantics↗

PubMed2001

Clinical application of tentorium cerebelli hiatus incision in treatment of severe and most severe brain injuries.

OBJECTIVE: To explore the role of tentorium cerebelli hiatus incision in treating severe and most severe brain injuries complicated by tentorial herniation. METHODS: From July 1994 to July 1999 tentorium cerebelli hiatus incision was done based on intracranial hematoma evacuation and bone flap craniectomy decompression in 70 cases of severe and most severe brain injuries complicated by tentorial herniation. RESULTS: Of the 70 cases, GCS 3-5 was in 23 and GCS 6-8 in 47; satisfactory recovery in 39 cases (55.7%), moderate disability in 12 (17.1%), severe deficit in 6 (8.6%), vegetative survival in 4 (5.7%) and 8 (11.4%) died. CONCLUSIONS: Tentoriun cerebelli incision is helpful in alleviating secondary brain stem injury from tentorial herniation and in reducing the disability and death rate of the patients.

Adolescent↗

PubMed2001

Observation of wounding characteristics in dogs wounded by super velocity projectile.

OBJECTIVE: To understand wounding characteristics in dogs wounded by super velocity projectile with a purpose of providing a basis for prevention and treatment of such wounds. METHODS: A specially-made explosive gun was used to shoot aluminium bullet weighing 3.0 g and 1.4 g to injure both legs of dogs at velocities of 2330 m/s, 3200 m/s and 4250 m/s, respectively, and the soap specially made was also shot. At the same time, steel ball of 1.03 g was shot with a Type 53 smooth chamber gun at a speed of 1280 m/s. Within 30 min after wounding, debridement and pathological anatomy were performed and specimens were taken for light microscope observation. RESULTS: When the dogs were wounded by the 3 g bullet at speed of 2330 m/s, the entrance of the left leg was penetrated explosively with a defect area of 225 cm(2), and the femur trunk was also injured and the residual femur had comminution fracture. The exit of the right leg was blindly wounded with a defect area of 63 cm(2), but only the skin was not penetrated. Both testes and part pelvis were injured too. Under light microscope, degenerative myofibers and bleeding of the spatium between the myofibers could be found at the place 4 cm away from the wounding track. Furthermore, serious bleeding of the bladder and blood vessels of the brain could be observed. The lungs showed changes of blast injury. Vacuolar change was presented in the cytoplasm of hepatocytes. Injuries of the animals in other two experimental groups were similar to those described above, but the defect area of the wounded track was 124 cm(2) in the group of 4250 m/s. Injuries caused by the steel ball were milder than caused by the explosive gun. The volume of the residual cavity in the soap was 5000 ml. CONCLUSIONS: The super-velocity projectile causes destructive damage to the local tissues and multi-organ injuries. Therefore, the practical medical care needs not only amputation but also management of multi-organ injuries.

Animals↗

PubMed2001

[In vitro effect of lovastatin on NB4 promyelocytic leukemia cells].

OBJECTIVE: To explore the effect of lovastatin(LOV) on cell growth, apoptosis and differentiation of NB4 cells and elucidate some of the possible mechanism. METHODS: Cell proliferation and viability were analyzed by MTT assay and trypan blue exclusion assay, cell differentiation by NBT reduction. Cell morphological examination, DNA electrophoresis, flow cytometry, TUNEL in situ hybridization and semi-quantitative RT-PCR were performed to determine cell apoptosis. H,K,N-ras gene expression was investigated by RT-PCR and p21Ras protein expression by flow cytometry. RESULTS: 1. LOV inhibited the proliferation of NB4 cells with a lC50 of 12.59 mumol/L. 2. LOV induced apoptosis of NB4 cells, affected the cell cycle progression and arrested NB4 cells in G1/S phase. Bcl-2 mRNA was down-regulated by LOV in a time-dependent manner. 3. LOV could not induce the differentiation of NB4. 4. LOV did not increase the expression of H,K,N-ras mRNA, but decrease p21Ras protein expression on the cellular membrane. CONCLUSION: LOV can inhibit proliferation, induce apoptosis and interfere with cell cycle progression, but not induce differentiation of NB4. Inhibition of p21Ras protein isoprenylation is considered to be the major mechanism of LOV affecting NB4 cells.

Antineoplastic Agents↗

PubMed2001

[Characteristics of nitrogen and phosphorus pollution in the middle and small creeks, suburban Shanghai].

1. The middle and small creeks in suburban Shanghai were under heavy eutropic condition, with high loadings of nitrogen, phosphorus and organic pollutants. KN, TP and CODCr of the surface water of them were several times greater than the critical values of Types V, the worst level of water. 2. Spatial variations of N and P pollution were observed, as the creeks in different places accepted different types and amounts of pollutants. Affected by domestic sewage, the creeks nearby residential areas were often heavily polluted by NH4+ and P. The creeks in agricultural fields were more easily polluted by NO3- than by NH4+ and phosphorus. The creeks nearby livestock farms often witnessed sudden soaring of NH4+ and P. 3. N and P loadings of the creeks were also affected by the seasonal evolvement of ecological environment. With the increase of temperature and biomass, NH4+ and NO3- in the surface water were largely consumed and decreased as a result; while organic N and particle P increased as the enhancement of suspending biological particles. NO2- in the surface water increased with temperature as nitrifying bacteria became active. Total P and water soluble P also showed the trend of enhancement with the intensification of biological activities, however, they were also controlled by the condition of pH and DO in the water. 4. At the height of the summer, the surface and bottom water of the creeks differed in N and P loadings. NH4+, soluble P and total reactive P in the bottom water were higher than those in the surface; while NO3- and NO2- in the surface were higher than those in the bottom. Such water-quality stratification inevitably resulted from the enhancement of phytoplankton in the surface water and intensified release of NH4+ and P from the sediments. In the autumn, as-the temperature decrease, such phenomenon declined gradually.

China↗

PubMed2001

[A quantitative pathological study on angiogenesis, vascular endothelial growth factor and inducible nitric oxide synthase in astrocytomas].

OBJECTIVE: To investigate whether the expression of vascular endothelial growth factor (VEGF) and inducible nitric oxide synthase (iNOS) are associated with angiogenesis and malignancy of astrocytomas. METHODS: Immunohistochemistry, semiquantitation and image analysis were used to study the expression features of VEGF and iNOS in 61 cases of astrocytomas having follow-up data. Factor VIII related antigen (FVIII RAg) was also analysed in reflecting the epithelial cell amount and the microvessel density. RESULTS: Microvessels in astrocytomas could be divided into seven types. The positive reaction areas and IA values of FVIIIRAg expression in the endothelium were significantly increased with the increase of tumor grade (P < 0.001) and VEGF labeling index (LI) (P < 0.05). The patients with high VEGF LIs (LI >or= 25%) had a poor prognosis. VEGF expression was significantly related to that of iNOS (P < 0.001), i.e., VEGF level was reduced along with the decrease of iNOS reaction. CONCLUSION: Detection of FVIIIRAg could reflect the angiogenesis activities in astrocytomas. VEGF and iNOS could up-regulate each other to promote angiogenesis and are of importance in determining the malignancy degree of astrocytomas.

Astrocytoma↗

PubMed2001

[Autologous dendritic cells eliciting cytotoxicity of bone marrow cells against chronic granulocytic leukemia].

OBJECTIVE: To investigate the activity of bone marrow cells activated by autologous dendritic cells (DC) to mediate cytotoxicity against chronic granulocytic leukemia (CGL) cells. METHODS: DC were separated from bone marrow mononuclear cells (BMMNC) of two CGL patients in hematological remission and harvested after 3 days of culture in IMDM containing autologous plasma, rhGM-CSF and rhTNFalpha at 37 degrees C, 5% CO(2) humidified atmosphere. BMMNC obtained from the patients were divided into 3 groups to set up Dexter systems: the control group, rhIL-2 containing, and the third group having DC added at day 4. After 10 days of culture, non-adherent cells were harvested and the changes of immunological phenotype and the percentage of P210 positive cells were analyzed. The cytotoxicity were assayed with two-colour flow cytometry. The non-adherent cells from all the 3 systems served as effector cells, those from control system as target cells. RESULTS: The cytotoxic activity against target cells was greater in the DC-activated effector cells than that in rhIL-2-activated ones. The percentages of death cells in target cells were 63.12% versus 42.59% (case 1) and 61.60% versus 21.46% (case 2), respectively. In addition, there was a marked increase in the death cell percentage in the DC-activated effector cells themselves after incubation with target cells. This phenomenon was not found in the rhIL-2-activated effector cells. The percentage of P210 positive cells was significantly lower in non-adherent cells after 10 days of culture in Dexter system, comparing with that in non-cultured BMMNC. The least P210 positive cells were found in those cultured with DC and the less in those with rhIL-2. CONCLUSION: Autologous DC were able to activate bone marrow cells to generate cytotoxicity against CGL cells. Their effect was greater than that of rhIL-2. These activated bone marrow cells might mediate graft versus leukemia effect in vivo.

Bone Marrow Cells↗

PubMed2001

[Improvement of combination chemotherapy tolerance of human umbilical cord blood CD(34)(+) cells transducted with double drug resistance genes by a bicistronic retroviral vector].

OBJECTIVE: To explore whether human umbilical cord blood hematopoietic progenitor cells transduced with human aldehyde dehydrogenase class 3 (ALDH3) and multidrug resistance gene (MDR1) could increase resistance to 4-hydroxycyclophosphamide (4-HC) and P-glycoprotein effluxed drugs. METHODS: A bicistronic retroviral vector G1Na-ALDH3-IRES-MDR1 cDNA was constructed and transfected the packaging cell lines GP + E86 and PA317 by LipofectAMINE method, using the medium containing VCR and 4-HC for cloning selection and ping-ponging supernatant infection between ecotropic producer clone and amphotropic producer clone, cord blood CD(34)(+) cells were enriched with a high-gradient magnetic cell sorting system (MACS), and then repeatedly transfected with supernatant of retrovirus containing human ALDH3 and MDR1 cDNA under stimulation of hematopoietic growth factors. PCR, RT-PCR, Southern blot, Northern blot, FACS and MTT assay were used to evaluate the transfection and expression of the double genes. RESULTS: The purity of cord blood CD(34)(+) cells was approximately 91% and the recovery rate was 72%. The highest titer of recombinant amphotropic retrovirus in the supernatant was up to 6.5 x 10(5) CFU/ml. The efficiency of gene transduction was 18%, 20% and 16.7% tested by colony formation, PCR and FACS, respectively. Rhodamine 123 efflux showed 16% transduced cells with P-gp function. No helper virus was found by both nested PCR and rescue assay. The MTT analysis showed a 3.5 to 6.8-fold increase of resistance of transducted cells to cyclophosphamide and P-glycoprotein effluxes drug as compared with the nontransduced cells. CONCLUSION: The efficiency and co-expression of this dual genes transfer system provided a foundation for ameliorating combination chemotherapy toxicity in clinical trial.

ATP Binding Cassette Transporter, Subfamily B↗