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Biomedical subjects

Yi Zhang

Publications and source records attributed to Yi Zhang.

At least 361 records · Page 20Linked to original sources
PubMed2004

Gamma-aminobutyric acidA receptors do not mediate the immobility produced by isoflurane.

Many inhaled anesthetics enhance the effect of the inhibitory neurotransmitter gamma aminobutyric acid (GABA), supporting the view that the GABAA receptor could mediate the capacity of inhaled anesthetics to produce immobility in the face of noxious stimulation (i.e., MAC, the minimum alveolar concentration required to suppress movement in response to a noxious stimulus in 50% of subjects). However, only limited in vivo data support the relevance of the GABAA receptor to MAC. In the present study we used two findings to test for the relevance of this receptor to immobilization for isoflurane: 1) differences among anesthetics in their capacity to enhance the response of receptor expression systems to GABA: isoflurane (considerable enhancement), xenon (minimal enhancement), and cyclopropane (minimal enhancement); and 2) studies showing that the spinal cord mediates MAC for isoflurane. If GABAA receptors mediate isoflurane MAC, then their blockade in the spinal cord should increase isoflurane MAC more than cyclopropane or xenon MAC and the MAC increase should be proportional to the in vitro enhancement of the GABAA receptor. To test this thesis, isoflurane, cyclopropane, or xenon MAC was determined in rats during intrathecal infusion of artificial cerebrospinal fluid (aCSF) via chronically implanted catheters. Then MAC was redetermined during infusion of 1 microL/min aCSF containing either 0.6 or 2.4 mg/mL picrotoxin, which noncompetitively blocks GABAA receptors. There was no consistent increase in MAC consequent to increasing the picrotoxin dose from 0.6 to 2.4 microg/min, which suggests that maximal blockade of GABAA receptors in the spinal cord had been achieved. Picrotoxin infusion increased MAC approximately 40% with all anesthetics. This indicates that GABA release in the spinal cord influences anesthetic requirement. However, the increase did not consistently differ among anesthetics and did not correlate with in vitro enhancement of GABAA receptors by these anesthetics. This supports the view that GABAA receptors do not mediate immobilization for isoflurane.

Anesthetics, Inhalation↗
PubMed2004

Gene therapy for proliferative ocular diseases.

Proliferative ocular diseases encompass a wide variety of pathological processes with adverse cellular differentiation, proliferation and migration as common features. Pathologies may involve neovascular responses associated with diabetic retinopathy, retinopathy of prematurity or age-related macular degeneration. These diseases are quite prevalent and account for substantial visual impairment and blindness worldwide. Although treatment strategies are largely surgical, advances in our understanding of the proteins crucial to cell transdifferentiation, proliferation and migration, along with better gene transfer techniques, have greatly increased the potential for biological treatment options. In this report, the most common proliferative ocular vascular diseases and existing therapeutic modalities will be reviewed and an overview of possible gene therapy options will be discussed, along with potential candidate genes.

Adenoviridae↗
PubMed2004

[Osteogenesis characteristics of cultured rat mesenchymal stem cells under bone induction condition].

OBJECTIVE: To investigate the osteogenesis characteristics of cultured rat mesenchymal stem cells (MSCs) under bone induction condition. METHODS: MSCs were isolated from adult rat by using density gradient separation method. The osteogenic inducers were compounds of Dexone, beta-glycerophosphate sodium and vitamin C. RESULTS: The MSC attachment formed soon after the seeding and grew into colonies with the appearance of fibroblastic cells. The osteogenic inducer with low dose of Dexone could promote the osteogenic differentiation of MSC. In the group of osteogenic inducer with low dose of Dexone, the expression of alkaline phosphatase (ALP) was remarkably increased after one week's induction, and the number of positive cells was (15.1 +/- 2.6), significantly higher than that of the control group (12.0 +/- 3.5) (P < 0.01). The calcified deposits began to appear in the group of osteogenic inducer with low dose of Dexone after one week's induction and was increased remarkably after three weeks, and the number of calcified deposits was (9.0 +/- 1.7), significantly higher than that of the control group (2.0 +/- 1.8) (P < 0.01). CONCLUSION: MSC can differentiate into osteogenesis by osteogenic induction and may be used to provide seed cells for bone tissue engineering.

Alkaline Phosphatase↗
PubMed2004

[Inhibition of 8-chloroadenosine on proteasome activity of HL-60 cells].

BACKGROUND & OBJECTIVE: The proteasome is a multicatalytic proteinase complex in eukaryotic cells, and it can be used as a new target for screening anti-tumor drugs according to certain previous researches. The inhibition activity of 8-CA (8-chloroadenosine, a new anti-tumor drug synthesized in our lab) in sarcoma 180, hepatocarcinoma 22, and human gastric carcinoma xenograft tumor has been confirmed. However,the relationship between the mechanism of the inhibition and proteasome is still unclear. The present study was designed to explore the effect of 8-CA on 3 kinds of enzyme activities (chymotrypsin-like activity, trypsin-like activity, and peptidyl-glutamyl- peptide hydrolyzing activity) of 20S proteasome in human progranulocyte leukemia HL-60 cells. METHODS: HL-60 cells were treated with 8-CA at different concentrations for 24, 48, and 72 hours. Then total protein of HL-60 cells was extracted, and the three enzyme activities of 20S proteasomes in the total protein was examined. And the chymotrypsin-like activity of the purified proteasome from the total protein was also examined by immunoprecipitation. The enzyme activity was indicated by fluorescence absorbance (A) produced by degradation of specific substrates by proteasomes. RESULTS: In HL-60 cells, three enzyme activities of the proteasomes were significantly inhibited after exposure to 0.1 micromol/L 8-CA for 48 hours; and the inhibition effect was concentration dependent. When the concentration of 8-CA reached 5 micromol/L, the inhibition rates of three proteasome activities (chymotrypsin-like activity,trypsin-like activity,and peptidyl- glutamyl-peptide hydrolyzing activity) were 44.96%, 54.52%, 48.36% for 48 hours and 67.53%, 70.48%, 64.08% for 72 hours, respectively. The inhibition rate of 1 micromol/L and 5 micromol/L 8-CA on chymotrypsin-like proteasome activity of HL-60 cells for 48 hours were 68.14% (P< 0.01) and 92.75% (P< 0.001), respectively. CONCLUSION: 8-CA inhibits proteasome activity of HL-60 cells with a time- and concentration-dependent manner.

2-Chloroadenosine↗
PubMed2004

Tetrandrine inhibits Ca2+-activated chloride channel in cultured human umbilical vein endothelial cells.

AIM: To characterize the electrophysiological and kinetic properties of Ca2+-activated chloride channel (CaCC) in cultured human umbilical vein endothelial cell line (HUVEC), and test the inhibitory effects of tetrandrine (Tet) on CaCC. METHODS: Ca2+-activated Cl- currents (I(Cl,Ca)) were recorded by patch-clamp whole cell configurations. [Ca2+]i was measured via intracellular Fura-2 fluorescence intensities. RESULTS: I(Cl,Ca) was activated by increasing [Ca2+]i via direct elevation of intracellular calcium. I(Cl,Ca) showed an apparent outward rectification properties, and it was activated in a voltage- and calcium-dependent mode. Tet dose-dependently inhibited I(Cl,Ca), the IC50 was (5.2+/-0.4) micromol/L (n=8 cells). Tet suppressed both voltage-dependent and calcium-dependent activation of I(Cl,Ca). The activation time constant was (326+/-12) ms [in the presence of 10 micromol/L Tet, compared to control (175+/-17) ms, at +100 mV], and Ca2+ concentration for half maximal activation was (387+/-61) nmol/L for Tet (compared to control (287+/-36) nmol/L. CONCLUSIONS: Tet effectively blocked I(Cl,Ca), and such effects might be due to its inhibitory effects on the activation process of Ca2+-activated chloride channel.

Alkaloids↗
PubMed2004

[Inhibiting effects of stroma cell drived factor 1 (SDF-1) on proliferation of human acute myelocytic leukemia cell HL-60].

This study was aimed to investigate the importance of chemokine SDF-1 in maintaining proliferation ability of acute myelocytic leukemia cell line HL-60 when the effects of SDF-1 on HL-60 cell proliferation were inhibited. Marrow stromal cells were cultured and co-cultured with HL-60 cells, and SDF-1 activity was blocked with anti-CXCR4 McAb. HL-60 cell activity was detected by MTT while cell cycle and the expression of CXCR4 on HL-60 cell membrane were observed by flow cytometry meanwhile. The internal calcium ionic concentration in HL-60 cell was detected as well before and after treated with 12G5. The results showed that 12G5 down-regulated the expression of CXCR4 on HL-60 cell membrane; HL-60 cells at G(0)/G(1) phase increased, but decreased at S phase; survive rate of leukemia cells reduced; the intercellular calcium ionic concentration of HL-60 cell decreased after treated with 12G5. It was concluded that brockage of the SDF-1 activity may inhibit proliferation of leukemia cell at certain level.

Antibodies, Monoclonal↗
PubMed2004

[Effects of leukemia bone marrow stromal cells on resistance of co-cultured HL-60 to idarubicin].

To study the role of hematopoietic microenvironment abnormality in development of minimal residual disease and its mechanism, the viability of HL-60 cells was investigated by means of bone marrow stromal cell culture system or co-culture system of bone marrow stromal cell with HL-60 cells and idarubicin (IDA), flow cytometry and ELISA. The results showed that viability of HL-60 cells gradually decreased along with the increase of IDA dose and prolongation of culture time. Amount of HL-60 cells co-cultured with leukemia bone marrow stramal cells was significantly increased as compared with that of the control (P < 0.05). Bone marrow stromal cells or stromal cell conditioned medium reduced the effect of IDA on HL-60 cells in culture. In conclusion, leukemia bone marrow stromal cells contribute to increasing resistance of HL-60 cells to chemotherapeutic agents, and play some role in developing minimal residual disease.

Bone Marrow Cells↗
PubMed2004

[Construction of a DNA vaccine against human B cell lymphoma].

AIM: To construct a DNA vaccine based on surface Ig V(H) gene of tumor cells in the human B-cell lymphoma biopsy tissue. METHODS: The V(H) gene fragment was amplified by RT-PCR using Ig superfamily primers. Also, the murine monocyte chemotactic protein 3(MCP-3) cDNA was cloned. The fusion gene fragment of MCP-3 gene with V(H) gene was constructed by recombinant PCR and then cloned into the eukaryotic expression vector pcDNA3.1 to construct the DNA vaccine plasmid pcDNA3.1/MCP-V(H). The vaccine plasmid was transiently expressed in the eukaryotic cell line COS-7. RESULTS: The DNA vaccine plasmid was successfully constructed and expressed in COS-7 cells in the form of fusion protein MCP-V(H). CONCLUSION: The DNA vaccine plasmid pcDNA3.1/MCP-V(H) is constructed and expressed successfully, which plays the foundation for further experimental research in animal model.

Animals↗
PubMed2004

[Expression of MAGE-1 and MAGE-3 genes in gastric cancer and gastric biopsy tissues and its clinical significance].

AIM: To detect the expression of melanoma antigen-1 and -3 genes (MAGE-1 and MAGE-3) and explore its significance in immunotherapeutic application. METHODS: The expression of MAGE-1 and MAGE-3 in gastric cancer, para-tumorous normal mucosa, and gastric biopsy tissues were detected by RT-PCR. The target genes in RT-PCR product were verified by means of DNA sequencing. RESULTS: MAGE-1 expression was positive in 26 out of 36 (72.22%) cases of gastric cancer, MAGE-3 positive in 25 out of 36(69.44%), and both MAGE-1 and MAGE-3 positive in 19 out of 36 (52.78%). Positive expression rates of MAGE-1, MAGE-3 and both MAGE-1 and MAGE-3 were 47.22%, 44.44% and 30.55%, respectively in para-tumorous normal mucosa, while 29.73%, 27.03% and 8.1% in gastric biopsy tissues The positive rates of MAGE-1 and MAGE-3 gene expressions in tumor tissues was significant higher than those its parallelism mucosae and biopsy tissues from chronic gastritis. The expressions of MAGE-1 and MAGE-3 genes in tumor tissues were relevant to intruded depth and the differentiated degree of tumor cells (P<0.05). CONCLUSION: MAGE-1 and MAGE-3 protein may be used as targets molecules of immunotherapy for gastric cancer and indexes for follow-up study of chronic gastritis as well.

Antigens, Neoplasm↗
PubMed2004

[A study on the classification and treatment of zygomatic complex fractures].

OBJECTIVE: To investigate a new classification and treatment of zygomatic complex fractures (ZCF) by clinical and radiographic studies. METHODS: Standard radiographs with Waters, submental vertex views had been obtained before and after operation in 206 patients (212 sides) with ZCF. Patients with complicated fractures underwent two and three dimensional CT. Computer-assisted measuring system was used to measure the degree of displacement. RESULTS: ZCF were classified into 3 types and 6 subtypes according to the degree of displacement of segments and facial deformities. Treatment principles were proposed. The results were satisfied through clinical application and measurement of post-operative images. CONCLUSIONS: The treatment for ZCF should be selected according to the fracture types. The key of operation is to recover the malar prominence. Remodeling the length and radian of zygomatic arch guarantee the recovery of malar prominence. Zygomatic-sphenoid and zygomatic-maxillary fissures are very important reference marks for reduction and fixation.

Adolescent↗
PubMed2004

Comparison of mesenchymal stem cells from human placenta and bone marrow.

BACKGROUND: Nowadays bone marrow represents the main source of mesenchymal stem cells (MSCs). We identified a new population of MSCs derived from human placenta and compared its biological characterization with bone marrow derived MSCs. METHODS: Mononucleated cells (MNC) were isolated from the human placenta tissue perfusate by density gradient fractionation. Individual colonies were selected and cultured in tissue dishes. At the same time, human bone marrow derived MSCs were identified. Culture-expanded cells were characterized by immune phenotyping and cultured under conditions promoting differentiation to osteoblasts or adipocytes. The hematopoietic cytokines were assayed using reverse transcriptase polymerase chain reaction (RT-PCR). RESULTS: Human placental MSCs exhibited fibroblastoid morphology. Flow cytometric analyses showed that the placental MSC were CD29, CD44, CD73, CD105, CD166, HLA-ABC positive; but were negative for CD34, CD45, and HLA-DR. Functionally, they could be induced into adipocytes or osteocytes. Moreover, several hematopoietic cytokine mRNA was found in placenta-derived MSCs by RT-PCR analysis, including IL-6, M-CSF, Flt3-ligand and SCF. These results were consistent with the properties of bone marrow derived MSCs. CONCLUSION: These observations implicate the postpartum human placenta as an important and novel source of multipotent stem cells that could potentially be used for investigating mesenchymal differentiation and regulation of hematopoiesis.

Bone Marrow Cells↗
PubMed2004

[Study on methods for quality control of recombinant human neu epitope peptide 12].

AIM: To establish methods and requirements for the quality control of recombinant human neu epitope peptide 12. METHODS: Biological activity of recombinant human neu epitope peptide 12 was evaluated in FVB/N transgenic mice (TgN MMTV neu 202 Mul, Jackson Lab., USA) administered with samples. The percentage of antibody-positive mice detected by ELISA was used in the biological activity evaluation. The peptide map was performed by peptic digestion. The antigen content was determined by SEC-HPLC. RESULTS AND CONCLUSION: The quality control methods, such as biological activity, peptide map, antigen content, and the requirements for the quality control of recombinant human neu epitope peptide 12 were established. The established methods and requirements were already used for the quality control of recombinant human neu epitope peptide 12 products.

Animals↗
PubMed2004

[Effects of anti- CXCR4 monoclonal antibody on adhesiveness of human acute myelocytic leukemia cell line HL-60 and expression of Bcl-2, Fas proteins].

To study the importance of chemokine SDF-1 in surviving of acute myelocytic leukemia cells HL-60, the adhesion ability of HL-60 and expression of Bcl-2, Fas protein when SDF-1 activity was blocked by anti-CXCR4 monoclonal antibody (12G5) were compared with those detected before MAb incubation, in this experiment, HL-60 cell were cultured and co-cultured with normal marrow stromal cell. The adhesion rate was detected while the expression of Bcl-2 and Fas proteins were assayed by immunohistochemical technique when SDF-1 activity was inhibited. The results showed that cell adhesion rate of HL-60 decreased while the expression Bcl-2 decreased and Fas increased. It is concluded that inhibition of SDF-1 activity increases cell apoptosis and thus reduces life-span of leukemia cell at certain level.

Antibodies, Monoclonal↗