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Biomedical subjects

Xiang Gao

Publications and source records attributed to Xiang Gao.

108 records · Page 6Linked to original sources
PubMed2003

[Protective effects of green tea on mice with the irradiating damage induced by gamma-ray].

OBJECTIVE: To evaluate the protective effects of green tea on mice with the irradiating damage induced by 60Co-gamma-ray. METHODS: Thirty-five mice were divided into normal control group, irradiating control group and three experiment groups. The mice of the experiment groups drank in water soluble extractives of green tea (1.25%, 2.5%, 5%) for two weeks. Then all animals were irradiated by 60Co-gamma-ray except those of the normal control group. The animals of three experiment groups continued drinking the water soluble extractives of green tea for one week, after that all mice of the five groups were killed. The levels of malondiadehyde (MDA) and the activities of superoxide dismutase (SOD) in serums, the optical density (OD) value of DNA and the number of karyota of femur, the frequency of micronuclei in polychromatophilic erythrocytes of bone marrow in mice of all groups were measured. RESULTS: Compared with the measurements in the irradiating control group, the level of MDA in serums and the frequency of micronuclei in polychromatophilic erythrocytes of bone marrow in the three experiment groups were decreased significantly (P < 0.05), while the activities of SOD in serums, the OD value of DNA and the number of karyota of femur in mice of the three experiment groups were increased significantly (P < 0.05). CONCLUSION: The water soluble extractives of green tea have protective effects on mice with the irradiating damage induced by gamma-ray.

Animals↗
PubMed2003

[Experimental study on DC corona radical shower for the removal of toluene].

Using DC corona radicals shower to decompose toluene in air, different parameters were studied, such as the concentration of toluene, temperature, voltage, humidity and the settled time. The results showed that the fall of temperature and appropriate humidity can increase the decomposing efficiency of toluene; the efficiency decreased with the increasing of the voltage; the settled time was longer, the decomposing efficiency was higher, but the energy efficiency decreased. Increasing the concentration of toluene made the removal efficiency lower, but in the same time, made the energy efficiency higher. The experiment built a good basis for researching radicals decompose PAHs(dioxins etc.).

Electric Conductivity↗
PubMed2002

Neuroimmune interactions in guinea pig stomach and small intestine.

Enteric neuroimmune interactions in gastrointestinal hypersensitivity responses involve antigen detection by mast cells, mast cell degranulation, release of chemical mediators, and modulatory actions of the mediators on the enteric nervous system (ENS). Electrophysiological methods were used to investigate electrical and synaptic behavior of neurons in the stomach and small intestine during exposure to beta-lactoglobulin in guinea pigs sensitized to cow's milk. Application of beta-lactoglobulin to sensitized preparations depolarized the membrane potential and increased neuronal excitability in small intestinal neurons but not in gastric neurons. Effects on membrane potential and excitability in the small intestine were suppressed by the mast cell stabilizing drug ketotifen, the histamine H(2) receptor antagonist cimetidine, the cyclooxygenase inhibitor piroxicam, and the 5-lipoxygenase inhibitor caffeic acid. Unlike small intestinal ganglion cells, gastric myenteric neurons did not respond to histamine applied exogenously. Antigenic exposure suppressed noradrenergic inhibitory neurotransmission in the small intestinal submucosal plexus. The histamine H(3) receptor antagonist thioperamide and piroxicam, but not caffeic acid, prevented the allergic suppression of noradrenergic inhibitory neurotransmission. Antigenic stimulation of neuronal excitability and suppression of synaptic transmission occurred only in milk-sensitized animals. Results suggest that signaling between mast cells and the ENS underlies intestinal, but not gastric, anaphylactic responses associated with food allergies. Histamine, prostaglandins, and leukotrienes are paracrine signals in the communication pathway from mast cells to the small intestinal ENS.

Anaphylaxis↗
PubMed2002

Neuronal apoptosis induced by endoplasmic reticulum stress.

Apoptosis is a conserved active cellular mechanism occurring under a range of physiological and pathological conditions. In the nervous system, apoptosis plays crucial roles in normal development and neuronal degenerating diseases. Various deleterious conditions, including accumulation of the mutant proteins in the endoplasmic reticulum (ER) and inhibition of ER to Golgi transport of proteins, may result in apoptosis. In this study, we examined the downstream events of apoptosis in differentiated PC 12 cells under ER stress induced by brefeldin A, an inhibitor of ER to Golgi protein transport. Activation of NF-kappaB and degradation of I-kappaB were observed within 2 hours, followed by up-regulation of GRP78 protein level in treated cells. Caspase-12 only appeared around 24 hours after brefeldin A treatment, coincident with cell nuclei fragmentation. These results suggest that neuronal apoptosis may be induced by ER stress through a NF-kappaB and caspase related pathway.

Animals↗
PubMed2002

Premarital sexual activities among students in a university in Beijing, China.

BACKGROUND: Sexually transmitted diseases are becoming a serious public health problem in China. College students are recognized as one of the age groups most affected. GOAL: The goal was to investigate premarital sexual activities and condom use among college students in Beijing in order to collect the information necessary for research on interventions. STUDY DESIGN: A cross-sectional survey was conducted in June 1999 among students at a university in Beijing. A self-administered, anonymous, structured questionnaire was used. RESULTS: Among those interviewed, 41% reported premarital sexual activities: 28% had kissed partners of the opposite sex, 19% had masturbated, and 12% had engaged in sexual intercourse. Among those who had sexual intercourse, 69% had used condoms. CONCLUSION: Today, more students are engaging in premarital sexual intercourse. Thus, it is necessary to reinforce reproductive health education among college students and provide convenient and optional services that are easily accessed.

Adolescent↗
PubMed2002

Ty5 gag mutations increase retrotransposition and suggest a role for hydrogen bonding in the function of the nucleocapsid zinc finger.

The Ty5 retrotransposon of Saccharomyces paradoxus transposes in Saccharomyces cerevisiae at frequencies 1,000-fold lower than do the native Ty1 elements. The low transposition activity of Ty5 could be due to differences in cellular environments between these yeast species or to naturally occurring mutations in Ty5. By screening of a Ty5 mutant library, two single mutants (D252N and Y68C) were each found to increase transposition approximately sixfold. When combined, transposition increased 36-fold, implying that the two mutations act independently. Neither mutation affected Ty5 protein synthesis, processing, cDNA recombination, or target site choice. However, cDNA levels in both single mutants and the double mutant were significantly higher than in the wild type. The D252N mutation resides in the zinc finger of nucleocapsid and increases the potential for hydrogen bonding with nucleic acids. We generated other mutations that increase the hydrogen bonding potential (i.e., D252R and D252K) and found that they similarly increased transposition. This suggests that hydrogen bonding within the zinc finger motif is important for cDNA production and builds upon previous studies implicating basic amino acids flanking the zinc finger as important for zinc finger function. Although NCp zinc fingers differ from the zinc finger motifs of cellular enzymes, the requirement for efficient hydrogen bonding is likely universal.

Amino Acid Sequence↗
PubMed2002

Macrophages are necessary for maximal nuclear factor-kappa B activation in response to endotoxin.

To define the role of macrophages in regulating the lung's response to Escherichia coli endotoxin (lipopolysaccharide [LPS]), depletion of macrophages was accomplished by administration of dichloromethylene diphosphonate (clodronate) delivered via intratracheal (i.t.) and/or intravenous (i.v.) routes. Clodronate reduced the number of macrophages in lung lavage 48 h after either i.t. or i.v. administration, but combined i.t. + i.v. clodronate achieved the most profound depletion (90%). Although i.t. clodronate alone had little effect on the evolution of lung inflammation, combined i.t. + i.v. clodronate treatment decreased neutrophilic alveolitis 4 h after exposure to aerosolized LPS by 80% compared with mice treated with empty liposomes. This decrease was associated with impaired activation of nuclear factor (NF)-kappa B and lower concentrations of tumor necrosis factor (TNF)-alpha in lung lavage fluid. Combined i.t. + i.v. clodronate markedly reduced lung NF-kappa B activation and the intensity of neutrophilic alveolitis after intraperitoneal (i.p.) LPS; however, i.v. clodronate alone had no effect on NF-kappa B activation in either liver or lung tissue or the development of neutrophilic alveolitis. We conclude that generalized macrophage depletion reduces NF-kappa B activation, generation of cytokines, and neutrophilic lung inflammation in response to gram negative bacterial endotoxin. These findings define the role of the macrophage as a critical component for initiation of the NF-kappa B-dependent innate immune response.

Administration, Inhalation↗
PubMed2001

Barotolerant E.coli Induced by High Hydrostatic Pressure.

The barotolerant E.coli TG1P, DH5alphaP, HB101P were obtained from TG1,DH5alpha, HB101 after treatment with high hydrostatic pressure, and the survival rates of the formers raised 2--3 magnitude, from 1.06x10(-6), 2.98x10(-4), 3.65x10(-3) to 8.31x10(-3), 3.40x10(-1), 1.69x10(-1),respectively. Comparison of partial proteomes of wild and barotolerant bacteria of TG1 and DH5alpha with two-dimensional electrophoresis showed that three proteins were obviously highly expressed in barotolerant bacteria. The N terminal sequence and molecular weight of one protein was shown to be V(L)EAGEFFMRA and 21 kD, with high identity to a known outmembrane protein in E.coli.

Journal Article↗
PubMed1999

N-cadherin Invovles in P19 Cell in vitro Neuronal Differentiation.

N-cadherin plays an important role in the early morphogenesis of neural tissue. For exploring the possible role of N-cadherin in neuronal differentiation in vitro, we chose RA induced P19 cell neuronal differentiation as a model system. Using RT-PCR, we examined the expression pattern of N-cadherin during P19 cell neuronal differentiation. The results showed that N-cadherin expression was increased rapidly during RA induction with its highest expression level at day 3 of neuronal differentiation, then down-regulated along with neuronal maturation. This expression pattern was similar with CNS development in vivo. Then, we constructed a N-cadherin expression-vector and transfected in P19 cells. The stable transfected cell lines, N-cadherin/P19 were selected, and we found that, after aggregated 4 days, the N-cadherin overexpression P19 cells could differentiate into neuron-like cells without the RA induction. The immunocytochemical staining showed that these neuron-like cells expressed neuron specific marker, NF160. These results suggest that N-cadherin gene is involved in P19 neuron differentiation.

Journal Article↗
PubMed1999

Potential GM-CSF Antagonists Selected from a Peptide Phage Display Library.

Peptide phage display libraries have been successfully applied in areas of mapping antibody epitope, finding ligands for enzymes, receptors, and many other molecules. But it has been demonstrated to be very difficult to select cytokine-binders from peptide phage display libraries probably because cytokine is not so sticky as antibody that there are rare chances of capturing peptide phages during biopanning. A pVIII-based peptide phage display library was panned with the cytokine GM-CSF and some GM-CSF binding clones were selected based on high throughput screening (HTS) method and confirmed by ELISA and micropanning assays. These cytokine-binders may be utilized in affinity chromatography in cytokine downstream processing and even act as potential antagonists of GM-CSF if their affinity are further improved through secondary library strategy.

Journal Article↗
PubMed1996

Prostate Cancer - Old Problems and New Approaches. (Part II. Diagnostic and Prognostic Markers, Pathology and Biological Aspects).

Diagnostic and prognostic markers for prostatic cancer (PCa) include conventional protein markers (e.g., PAP, PSA, PSMA, PIP, OA-519, Ki-67, PCNA, TF, collagenase, and TIMP 1), angiogenesis indicator (e.g., factor VIII), neuroendocrine differentiation status, adhesion molecules (E-cadherin, integrin), bone matrix degrading products (e.g., ICPT), as well as molecular markers (e.g., PSA, PSMA, p53, 12-LOX, and MSI). Currently, only PSA is used clinically for early diagnosis and monitoring of PCa. The histological differential diagnosis of prostatic adenocarcinoma includes normal tissues such as Cowper's gland, paraganglion tissue and seminal vesicle or ejaculatory duct as well as pathological conditions such as atypical adenomatous hyperplasia, atrophy, basal cell hyperplasia and sclerosing adenosis. A common PCa is characterized by a remarkable heterogeneity in terms of its differentiation, microscopic growth patterns and biological aggressiveness. Most PCa are multifocal with signi ficant variations in tumor grade between anatomically separated tumor foci. The Gleason grading system which recognizes five major grades defined by patterns of neoplastic growth has gained almost uniform acceptance. In predicting the biologic behavior of PCa clinical and pathological stages are used as the major prognostic indicators. Among the cell proliferation and death regulators androgens are critical survival factors for normal prostate epithelial cells as well as for the androgen-dependent human prostatic cancer cells. The androgen ablation has been shown to increase the apoptotic index in prostatic cancer patients and castration also promotes apoptotic death of human prostate carcinoma grown in mice. The progression of PCa, similarly to other malignancies, is a multistep process, accompanied by genetic and epigenetic changes, involving phenomenons as adhesion, invasion and angiogenesis (without prostate specific features).

Journal Article↗
PubMed1996

Prostate Cancer Old Problems and New Approaches. Part III. Prevention and Treatment.

In Part Three of this review, we begin with an analysis of prevention strategies for prostate cancer followed by a discussion of the clinical use of molecular techniques for the evaluation and treatment of patients with clinically localized prostate cancer. New developments in neutron and photon therapy of prostate cancer are addressed as well as the use of systemic radiotherapy for the treatment of bone metastases. Finally, we conclude with the role of hormonal therapy in the treatment of prostate cancer and the current status of development of chemo therapeutic regimens for the treatment of prostate cancer.

Journal Article↗
PubMed1995

Recessive oncogenes: current status.

Cell growth is under the control of a variety of positive and negative signals. An imbalance of such signals results in deregulation of cell behavior. Recessive oncogenes or tumor suppressor genes, opposite to dominant oncogenes, encode important cellular proteins which could function as negative regulators of the cell cycle, i.e., cell cycle brakes. Inactivation of recessive oncogenes, by allelic deletion, loss of expression, mutation, or functional inactivation by interacting with oncogene products of DNA tumor viruses or with amplified cellular binding proteins, will lead to uncontrolled cell growth or tumor formation. Besides the classic suppressor genes such as the p53 and RB, a growing number of novel tumor suppressor genes have been identified in recent years. While some tumor suppressor genes have been found to be important for the development of a large number of human malignancies (e.g., the p53 gene), others are more tumor type-specific (e.g., the NF-1 gene). Many human cancer types showed abnormalities of multiple tumor suppressor genes, offering strong support to the concept that tumorigenesis and progression result from an accumulation of multiple genetic alterations. In this review, we will begin with an overview (gene, transcript, protein and mechanisms of action) of the tumor suppressor genes (the RB, p53, DCC, APC, MCC, WT1, VHL, MST1, and BRCA1 genes) identified to date and then discuss the specific involvement of tumor suppressor genes in human malignancies including prostate cancer. Various chromosomal regions which potentially may contain tumor suppressor genes also will be reviewed.

Journal Article↗
PubMedDate not supplied

Quantitative analysis of EcoR1 methylase-DNA complex by atomic force microscopy.

The EcoR1 methylase specifically recognize 5'-GA* ATTC-3' in DNA duplex. We directly applied atomic force microscopy (AFM) to investigate linear pBR322-EcoR1 methylase complexes and quantitatively analyzed the bend angles of linear pBR322-EcoR1 methylase complexes and the bound protein widths. In this study, we made a novel observation that DNA-EcoR1 methylase complexes exhibited two populations of conformation at recognition site: DNA bent an acute angle at the recognition site in the presence of one EcoR1 methylase monomeric molecule, while DNA bent an unacute angle at the recognition site and the complementary site on duplex DNAs in the presence of EcoR1 methylase dimer. The data indicated that the unacute angle state was the result of unique interactions between EcoR1 methylase and the recognition site and the complementary site on duplex DNAs, and suggested that the acute angle conformation could be an intermediate in the formation of the unacute angle state. Our works provide a detail insight into the DNA structural variations involved in EcoR1 methylase-binding processes and demonstrate further the versatility of AFM as an imaging technique for studying the interaction between large DNA fragment and protein.

Binding Sites↗
PubMedDate not supplied

Cellular cardiomyoplasty for a patient with heart failure.

BACKGROUND: A 73-year-old man with a history of myocardial infarction and hypertension for 5 years suffered heart failure (NYHA III-IV). METHODS: 2D echo indicated hypokinesia at septal, left ventricular anterior wall and apical regions. Coronary angiograms demonstrated 60% stenosis in distal left main and 99% stenosis in proximal and distal left anterior descending coronary arteries (LAD). Both proximal artery and middle left circumflex coronary artery (LC) had 90% stenosis, and diffuse stenosis of right coronary artery (RC) was found. Myocardial perfusion imaging using 99mTc-MIBI indicated defective perfusion of left ventricular apex, anterior wall and septal region and severe reduced perfusion of posterior inferior wall. Myocardial metabolic activities (18F-deoxyglucose) also showed comparable reductions. After exposing the heart, LAD, LC, and RC were all completely occluded and bypass procedure could not be completed. Autologous satellite cells were implanted without any complication and the patient had an uneventful recovery. RESULTS: During the first 2 months, he remained in heart failure, and by the third month, he gradually improved and reached NYHA II. At fifth month after the procedure, significant increased ejection fraction (37.1-48.6%) and wall movement with modest reduction of left ventricular systolic diameter (48-45 mm) were observed. Imaging with 18F-deoxyglucose showed dramatic improvement in myocardial metabolic activity with similar improvement in myocardial perfusion (99mTc-MIBI). CONCLUSION: This is the first successful case of cellular cardiomyoplasty without any conjunctional procedure for patient with severe coronary heart disease and heart failure.

Aged↗
PubMedDate not supplied

Cellular cardiomyoplasty: a preliminary clinical report.

BACKGROUND: Cellular cardiomyoplasty is the method of transplanting myogenic cells into injured myocardium to restore the lost heart muscle cells and to improve ventricular function. METHOD: Three patients, all with a history of coronary heart disease, underwent coronary artery bypass grafting and implantation of autologous satellite cells. A muscle biopsy of 2-4 g from the right vastus lateralis muscle was obtained for satellite cell (myogenic stem cell from skeletal muscle) isolation and proliferation before implanted into the donor's heart. The cells were suspended in serum-free medium and injected into 30-40 sites at and around the ischemic areas just before reversing the hypothermic cardioplegia to eliminate arrhythmia and to improve retention. After recovery, each patient was maintained at the intensive care unit for 3-4 days with ECG monitoring before transferring to the patient floor. RESULTS: All patients survived the procedure with an uneventful recovery and were discharged from the hospital. At 3-4 months follow-up examination, increased left ventricular ejection fraction of 11% (35-46%), 5.4% (40-45.4%) and 1% (40-41%) and decreased left ventricular diastolic diameter of 4, 2 and 9 mm were observed for the patients, respectively. Arrhythmia was not detected during the follow-up evaluation by ECG. Improved perfusion (99mTC-MIBI) and increased metabolic activity (18F-deoxyglucose) were found at the sites of satellite cell implantation. Significant increase of wall thickness and movement at the areas of cell injection was also observed using 2D-echo. CONCLUSION: Cellular cardiomyoplasty using autologous satellite cells is a safe procedure with encouraging beneficial outcomes in patients.

Aged↗
PubMedDate not supplied

Clinical cellular cardiomyoplasty: technical considerations.

Three patients, all with a history of coronary heart disease, underwent coronary artery bypass grafting and implantation of autologous satellite cells. Satellite cells were isolated from muscle biopsies of the right vastus lateralis muscle after enzymatic treatment. While the heart was still under hypothermic cardioplegia, 4 mL of cell suspension divided into approximately 40 doses was injected into the ventricular wall of the ischemic area. Less than 5 minutes were required to complete the cell implantation. All patients survived the procedure, without obvious arrhythmia, had an uneventful recovery, and were discharged from the hospital. At 3 to 4 months follow-up examination, increased left ventricular ejection fraction, decreased left ventricular diastolic diameter, as well as improved ventricular wall thickness and perfusion at the satellite cell implantation sites were observed. Our experience indicated the safety and early benefit of cellular cardiomyoplasty using autologous satellite cells.

Aged↗