Search PubMed⌕ Search

Biomedical subjects

Y Zou

Publications and source records attributed to Y Zou.

At least 109 records · Page 6Linked to original sources
PubMed2000

[Effect of rice variety resistance on population dynamics of Nilaparvata lugens and Sogatella furcifera].

The effect of rice varieties with different insect-resistance on dynamics of Nilaparvata lugens and Sogatella furcifera population was examined, based on the investigation of their inhabiting ratio, egg amount, survival rate of egg and nymph, nymph development, and the amount of their offspring population. Four rice varieties, TN1, N22, AsD7 and Ptb33 were investigated. Ptb33 had a significantly lower inhabiting ratio, egg amount, and survival ratio of eggs and nymphs of both parasitic populations, a prolonged development time from nymphs to adults, and an inhibited offspring population, indicating an evident resistance of this host variety. N22 and AsD7 inhibited the development of offspring S. furcifera and N. lugens, respectively. The parasitic populations of S. furcifera and N. lugens developed more rapidly on TN1, compared with N. lugens population on N22 and S. furcifera on AsD7. The relationship between the quantitative dynamics of both population and rice variety replacement was discussed, and the possibility of using resistant rice varieties to control these two insect populations was also analyzed.

Animals↗
PubMed2000

[Grey system analysis on dominant natural enemies influencing Aphis gosspyii population].

The populations of Aphis gosspyii and its natural enemies before cotton boll stage were investigated systematically in 1983, 1984, 1986, 1988, 1994 and 1995. The relationship between daily total predation of natural enemies and Aphis gosspyii population size was studied with the grey system theory and method, and the relational grade of various natural enemies to ideal superior natural enemies was analyzed. The results show that Propylaca japonica was the major natural enemy influencing Aphis gossypii, followed by Chrysopa septempunctata, then by Therdion octomaculatum and Erigonidium graminicola.

Animals↗
PubMed2000

[Geostatistical analysis on spatial patterns of Aphis gossypii and Propylaca japonica].

The spatial construction and distribution of Aphis gossypii and Propylaca japonica at different period were investigated with geostatistics. The results showed that the semivariogram of Aphis gossypii was described by spherical model, indicating an aggregated spatial arrangement, the range was 8.21-10.81 m. The semivariograms of Propylaca japonica was fitted by spherical model too, also indicating an aggregated spatial arrangement, its range was 8.01-14.25 m. The amount and spatial distribution of Propylaca japonica was closely related to that of Aphis gossypii. It reveals that Propylaca japonica is dominant natural enemies of influencing population of Ahphis gossypii.

Animals↗
PubMed2000

[Clinical observation of taxotere in the treatment of advanced non-small-cell lung cancer and breast cancer].

OBJECTIVE: To observe the response rate and toxic reaction of taxotere in the treatment of advanced NSCLC and breast cancer. METHODS: A total of 24 cases was included in the study. Taxotere 75 mg/m2 i.v. drip for 1 hour; dexamethasone 8 mg bid 24 hour before taxotere, and continued for 3 days. For NSCLC, the taxotere was combined with DDP 90 mg/m2; for breast cancer, it was combined with ADM 40 mg/m2. The second treatment cycle was given after 3 weeks. At last 2 cycles were given. RESULTS: In 15 NSCLC patients, there were 6 PR, 7 NC and 2 PD. In 9 breast cancer patients, there were 2 CR, 6 PR and 1 NC. The major toxic reactions were neutropenia, diarrhea, fatigue, muscle pain and alopecia. Grade 3 and grade 4 neutropenia occurred in 9 and 4 cases, respectively. Decrease in hemoglobin and thrombocytopenia were mild. Diarrhea occurred in 19 cases and allergic reaction in 1 case. CONCLUSION: Taxotere is effective in the combined treatment of advanced NSCLC and breast cancer. The toxic reactions are tolerable.

Adult↗
PubMed2000

[An analysis of bacterial culture results in infectious endophthalmitis].

OBJECTIVE: To study the changes of positive rate of bacterial culture of vitreous specimens from patients with infectious endophthalmitis during the past ten years and search for sensitive antibiotics for its treatment. METHODS: Vitreous specimens were taken from 304 eyes of 304 cases with clinically diagnosed infectious endophthalmitis for bacterial culture, and drug sensitivity test was carried out for the positive specimens. RESULTS: Bacterial positive rate was 53% with insignificant changes among the different years. Cefoperazone was the most sensitive antibiotic. CONCLUSION: Bacterial culture combined with drug sensitivity test of vitreous specimens is important in guiding the treatment of infectious endophthalmitis.

Adolescent↗
PubMed2000

[A histopathologic and immunohistochemical study of prognostic factors in esophageal squamous cell carcinoma].

OBJECTIVE: To investigate the prognostic value of various histopathological features and expression of immuno-phenotypes in esophageal squamous cell carcinoma (ESCC). METHODS: The tumor samples from 97 primary ESCC patients with potentially curative resection were evaluated for the following parameters: tumor size, grade of differentiation, pattern of invasion, depth of invasion, degree of lymphocyte infiltration, lymph node metastasis, TNM stage and p53, EGFR, c-erbB-2, nm23, cathepsin D protein expression. The prognostic impact of these parameters were analyzed by univariate and multivariate survival analyses. RESULTS: In the univariate Kaplan Meier analysis, poor differentiation, infiltrating growth pattern, invasion reaching adventitia, absent lymphocytic infiltration, lymph node metastasis, high staging, EGFR positive expression and nm23 negative expression were all associated with lower survival rate (Log-rank test, P < 0.05, respectively). However, the multivariate Cox analysis demonstrated that only pattern of invasion (RR = 2.000), degree of lymphocyte infiltration (RR = 0.509), TNM stage (RR = 1.733), EGFR expression (RR = 1.812) and c-erbB-2 expression (RR = 2.364) were significant prognostic factors (P < 0.05, respectively). CONCLUSION: For ESCC, the pattern of invasion, degree of lymphocyte infiltration, EGFR and c-erbB-2 protein expression had independent prognostic values as well as the TNM stage. Comprehensive analysis of these parameters can be helpful to identify biological behavior of ESCC and predict more accurately the prognosis of patients with ESCC.

Adult↗
PubMed2000

[Protective effect of hepatocyte growth factor on hepatocyte poisoning by carbon tetrachloride and related gene expression in rats].

Hepatocyte growth factor (HGF), as a pleiotropic factor, plays important roles in organ regeneration, organogenesis and morphogenesis, but few reports on protective effect of HGF on injured liver are available. The aim of this work was to investigate protective effects of recombinant human HGF (rhHGF) on intoxicated hepatocytes induced by carbon tetrachloride (CCl4). The results are as follows: (1) rhHGF (5 ng/ml) could significantly increase the viability of hepatocytes intoxicated by CCl4 (15 mmol/L), decrease the leakage of intracellular alanine transaminase (ALT) and potassium ions into the culture medium; (2) the combination of rhHGF (5 ng/ml) and epidermal growth factor (EGF) (50 ng/ml) could increase the viability further, decrease the leakage of intracellular ALT and potassium ions of hepatocytes; (3) high expression of HGF and its receptor/c-met gene in regenerating liver after partial hepatectomy and CCl4 (50%, 2.5 ml/kg bw) poisoning were examined respectively by reverse transcription-polymerase chain reaction in rats. The results showed that rhHGF could protect hepatocytes against CCl4 through preventing intracellular ALT and potassium ion leakage, thus suggesting a synergistic effect of rhHGF and EGF on cytoprotection, and high expression of HGF and its receptor/c-met mRNA in the liver treated with PH and CCl4 poisoning. The present study suggests that the expression of HGF and its receptor gene plays an important role in liver regeneration and repair.

Animals↗
PubMed2000

[Clinical and histopathological studies of melanocytoma of the optic disc].

OBJECTIVE: To examine the clinical features that may be useful in determining the malignant transformation of a melanocytoma of the optic disc. METHODS: The clinical documentation of 10 cases, including visual acuity, visual field, fundus findings and fluorescein angiogram were analyzed retrospectively. Three of them undergone histopathologic examinations. RESULTS: A benign melanocytoma may have some degree of decreased visual acuity, progressive nerve fiber bundle defect, certain amount of pigment dispersion into the vitreous, slight macular exudation and extension of the tumor tissue into the peripapillary area of the retina. CONCLUSION: The progression of the associated clinical symptoms and signs appears to be not necessarily indicative of a malignant transformation of the benign disease unless they are associated with rapid enlargement of the tumor mass as well as marked pigmentary changes of the tumor surface.

Adolescent↗
PubMed1999

Calcineurin plays a critical role in pressure overload-induced cardiac hypertrophy.

BACKGROUND: Cardiac hypertrophy is a fundamental adaptive response to hemodynamic overload; how mechanical load induces cardiac hypertrophy, however, remains elusive. It was recently reported that activation of a calcium-dependent phosphatase, calcineurin, induces cardiac hypertrophy. In the present study, we examined whether calcineurin plays a critical role in pressure overload-induced cardiac hypertrophy. METHODS AND RESULTS: Pressure overload produced by constriction of the abdominal aorta increased the activity of calcineurin in the rat heart and induced cardiac hypertrophy, including reprogramming of gene expression. Treatment of rats with a calcineurin inhibitor, FK506, inhibited the activation of calcineurin and prevented the pressure overload-induced cardiac hypertrophy and fibrosis without change of hemodynamic parameters. Load-induced expression of immediate-early-response genes and fetal genes was also suppressed by the FK506 treatment. CONCLUSIONS: The present results suggest that the calcineurin signaling pathway plays a pivotal role in load-induced cardiac hypertrophy and may pave the way for a novel pharmacological approach to prevent cardiac hypertrophy.

Animals↗
PubMed1999

MAPK superfamily plays an important role in daunomycin-induced apoptosis of cardiac myocytes.

BACKGROUND: Although anthracyclines, such as daunomycin (DM) and adriamycin, are potent chemotherapeutic agents, they have serious adverse effects, including cardiac toxicity. In the present study, we investigated the molecular mechanisms of DM-induced cardiomyocyte impairment. METHODS AND RESULTS: When cultured cardiac myocytes of neonatal rats were exposed to 1 micromol/L DM for 24 hours, many cells became positive for TUNEL staining, with morphological changes characteristic of apoptosis. Fragmentation of DNA into oligonucleosome-size fragments was recognized by agarose gel electrophoresis in DM-treated myocytes. DM activated 3 members of the mitogen-activated protein kinase (MAPK) family dose-dependently, such as extracellular signal-regulated protein kinases (ERKs), c-Jun NH(2)-terminal kinases, and p38 MAPK in cardiac myocytes. Oxyradical scavengers or Ca(2+) chelators inhibited DM-induced activation of ERKs and p38 MAPK. DM-induced activation of ERKs was also inhibited by overexpression of dominant negative mutants of Ras (D.N.Ras), and the p38 MAPK activation was attenuated by D.N.Rho. The number of DM-induced apoptotic cells was markedly increased when the ERK signaling pathway was selectively blocked by a specific MAPK/ERK kinase inhibitor, PD98059, whereas pretreatment with a specific inhibitor of p38 MAPK, SB203580, significantly reduced the amount of apoptosis. CONCLUSIONS: These results suggest that DM activates MAPKs through reactive oxygen species and Ca(2+) and that the MAPK family plays important roles in DM-induced apoptosis in cardiac myocytes. ERKs protect cardiomyocytes from apoptosis, whereas p38 MAPK is involved in the induction of cardiomyocyte apoptosis.

Animals↗
PubMed1999

Strand opening by the UvrA(2)B complex allows dynamic recognition of DNA damage.

Repair proteins alter the local DNA structure during nucleotide excision repair (NER). However, the precise role of DNA melting remains unknown. A series of DNA substrates containing a unique site-specific BPDE-guanine adduct in a region of non-complementary bases were examined for incision by the Escherichia coli UvrBC endonuclease in the presence or absence of UvrA. UvrBC formed a pre-incision intermediate with a DNA substrate containing a 6-base bubble structure with 2 unpaired bases 5' and 3 unpaired bases 3' to the adduct. Formation of this bubble served as a dynamic recognition step in damage processing. UvrB or UvrBC may form one of three stable repair intermediates with DNA substrates, depending upon the state of the DNA surrounding the modified base. The dual incisions were strongly determined by the distance between the adduct and the double-stranded-single-stranded DNA junction of the bubble, and required homologous double-stranded DNA at both incision sites. Remarkably, in the absence of UvrA, UvrBC nuclease can make both 3' and 5' incisions on substrates with bubbles of 3-6 nucleotides, and an uncoupled 5' incision on bubbles of >/=>/=10 nucleotides. These data support the hypothesis that the E.coli and human NER systems recognize and process DNA damage in a highly conserved manner.

Adenosine Triphosphatases↗
PubMed1999

Inhibition of neointima hyperplasia of mouse vein grafts by locally applied suramin.

BACKGROUND: Saphenous vein grafts are widely used for aortocoronary bypass surgery as treatment for severe atherosclerosis and often are complicated by subsequent occlusion of the graft vessel. METHODS AND RESULTS: We described a mouse model of venous bypass graft arteriosclerosis that can be effectively retarded by locally applied suramin, a growth factor receptor antagonist. Mouse isogeneic vessels of the vena cava veins pretreated with suramin were grafted end to end into the carotid arteries and enveloped with a mixture of suramin (1 mmol/L) and pluronic-127 gel. In the untreated group, vessel wall thickening was observed as early as 1 week after surgery and progressed to 4-fold and 10-fold the original thickness in grafted veins at 4 and 8 weeks, respectively. Pluronic-127 gel alone did not influence neointima formation. Suramin treatment reduced the neointima hyperplasia 50% to 70% compared with untreated controls. Immunohistochemical studies demonstrated that a significant proliferation of vascular smooth muscle cells (SMCs) constituted neointimal lesions between 4 and 8 weeks. The majority of SMCs expressed platelet-derived growth factor (PDGF) receptors-alpha and -beta, which were significantly reduced by suramin treatment. In vitro studies indicated that suramin completely blocked PDGF receptor activation or phosphorylation stimulated by PDGF-AB, inhibited activation of mitogen-activated protein kinase (ERK) kinases (MEK1/2) and ERK1/2, and abrogated transcription factor AP-1 DNA-binding activity. CONCLUSIONS: Suramin inhibited SMC migration and proliferation in vivo and in vitro by blocking PDGF-initiated PDGF receptor and MAPK-AP-1 signaling. These findings indicate that locally applied suramin is effective in a mouse model of venous bypass graft arteriosclerosis.

Animals↗
PubMed1999

Both Gs and Gi proteins are critically involved in isoproterenol-induced cardiomyocyte hypertrophy.

Activation of beta-adrenoreceptors induces cardiomyocyte hypertrophy. In the present study, we examined isoproterenol-evoked intracellular signal transduction pathways leading to activation of extracellular signal-regulated kinases (ERKs) and cardiomyocyte hypertrophy. Inhibitors for cAMP and protein kinase A (PKA) abolished isoproterenol-evoked ERK activation, suggesting that Gs protein is involved in the activation. Inhibition of Gi protein by pertussis toxin, however, also suppressed isoproterenol-induced ERK activation. Overexpression of the Gbetagamma subunit binding domain of the beta-adrenoreceptor kinase 1 and of COOH-terminal Src kinase, which inhibit functions of Gbetagamma and the Src family tyrosine kinases, respectively, also inhibited isoproterenol-induced ERK activation. Overexpression of dominant-negative mutants of Ras and Raf-1 kinase and of the beta-adrenoreceptor mutant that lacks phosphorylation sites by PKA abolished isoproterenol-stimulated ERK activation. The isoproterenol-induced increase in protein synthesis was also suppressed by inhibitors for PKA, Gi, tyrosine kinases, or Ras. These results suggest that isoproterenol induces ERK activation and cardiomyocyte hypertrophy through two different G proteins, Gs and Gi. cAMP-dependent PKA activation through Gs may phosphorylate the beta-adrenoreceptor, leading to coupling of the receptor from Gs to Gi. Activation of Gi activates ERKs through Gbetagamma, Src family tyrosine kinases, Ras, and Raf-1 kinase.

Animals↗
PubMed1999

Rho family small G proteins play critical roles in mechanical stress-induced hypertrophic responses in cardiac myocytes.

-Mechanical stress induces a variety of hypertrophic responses, such as activation of protein kinases, reprogramming of gene expression, and an increase in protein synthesis. In the present study, to elucidate how mechanical stress induces such events, we examined the role of Rho family small GTP-binding proteins (G proteins) in mechanical stress-induced cardiac hypertrophy. Treatment of neonatal rat cardiomyocytes with the C3 exoenzyme, which abrogates Rho functions, suppressed stretch-induced activation of extracellular signal-regulated protein kinases (ERKs). Overexpression of the Rho GDP dissociation inhibitor (Rho-GDI), dominant-negative mutants of RhoA (DNRhoA), or DNRac1 significantly inhibited stretch-induced activation of transfected ERK2. Overexpression of constitutively active mutants of RhoA slightly activated ERK2 in cardiac myocytes. Overexpression of C-terminal Src kinase, which inhibits functions of the Src family of tyrosine kinases, or overexpression of DNRas had no effect on stretch-induced activation of transfected ERK2. The promoter activity of skeletal alpha-actin and c-fos genes was increased by stretch, and these increases were completely inhibited by either cotransfection of Rho-GDI or pretreatment with C3 exoenzyme. Mechanical stretch increased phenylalanine incorporation into cardiac myocytes by approximately 1.5-fold compared with control, and this increase was also significantly suppressed by pretreatment with C3 exoenzyme. Overexpression of Rho-GDI or DNRhoA did not affect angiotensin II-induced activation of ERK. ERKs were activated by culture media conditioned by stretch of cardiomyocytes without any treatment, but not of cardiomyocytes with pretreatment by C3 exoenzyme. These results suggest that the Rho family of small G proteins plays critical roles in mechanical stress-induced hypertrophic responses.

Angiotensin II↗
PubMed1999

[Isolating the ends of yeast artificial chromosome by inverse polymerase chain reaction].

OBJECTIVE: To establish a highly efficient method for isolating yeast artificial chromosome(YAC) ends. METHODS: Based on the sequence of TAC vector, the frequent cutting enzymes were used to cleave within the vector and the genomic insert to generate relatively small fragments,which were ligated and subsequently amplified using vector primers that are in inverse orientation. The PCR products were purified and sequenced. RESULTS 8 YAC termini were isolated from YAC 776E2,964C5,11D8 and 8D1. CONCLUSION: The results suggest that inverse PCR be an efficient method for isolating YAC termini.

Chromosomes, Artificial, Yeast↗
PubMed1999

Transferrin receptor overexpression enhances transferrin responsiveness and the metastatic growth of a rat mammary adenocarcinoma cell line.

We previously found that breast cancer cell transferrin receptor expression and proliferative response to transferrin often correlated with metastatic capability. To further explore this, we transfected mammary tumor cells with a cDNA coding for the transferrin receptor and examined the effects of its overexpression on various cellular properties. A human transferrin receptor expression plasmid was made by excising the cDNA for the receptor from pcDTR1 and ligating it into the multiple cloning site of pcDNAINeo. The resulting construct was transfected into the poorly metastatic rat MTLn2 line that expresses low endogenous levels of rat transferrin receptor, and transfection-induced receptor expression was ascertained using antibodies specific for the human protein. Approximately 50% of the initial geneticin-resistant transfected MTLn2 cells overexpressed human transferrin receptor protein. High expressors were further isolated by four sequential FACS sorts. The final cell population expressed approximately 3-7 times more cell surface transferrin receptor than did vector transfected controls. Both lines proliferated at the same rate in normal (medium plus 5% FBS) culture conditions. However, in serum-free conditions, the transferrin receptor overexpressor cells displayed a pronounced proliferative response to transferrin whereas the control line did not. When injected into the mammary fat pads of female nude mice, cells from both lines formed micrometastases to the lung that were specifically visualized by immunohistochemical staining of rat cytokeratin 17. This revealed that the transferrin receptor transfected line formed larger lesions of this nature than did cells from the vector transfected controls. When injected into the tail vein of female nude mice, the transferrin receptor overexpressors likewise formed gross lung metastases of remarkably greater size than did the vector only transfectants. Overexpression of cell surface human transferrin receptor on MTLn2 cells appeared to affect their in vitro growth response to transferrin and their ability to grow at a secondary site in vivo.

Adenocarcinoma↗
PubMed1999

Efficiency of leukocyte removal by filters made of superfine glass fiber membranes.

BACKGROUND AND OBJECTIVES: To demonstrate the application of leukocyte removal filters made of a new type of filter material - superfine glass fiber - for depleting leukocytes in SAGM red cell suspensions and preventing nonhemolytic transfusion reactions. MATERIALS AND METHODS: The extent of leukocyte depletion and red cell recovery was based on cell counts. Trace leukocytes were counted in a 50-microl Nageotte counting chamber or by using a flow cytometer. The chemical stability of the glass fiber membranes was studied by plasma emission spectrometer and by measuring the ion content and weighing nonvolatile matter in water extract. The structural stability of the glass fiber membranes was studied by a micropore-filter membrane method. RESULTS: Leukocyte removal filters made of superfine glass fiber membranes removed more than 99.0% of leukocytes in SAGM red cell suspensions prepared from 400 ml whole blood. Red cell recovery exceeded 90%, and the total number of residual leukocytes was less than 5x10(6). A water extract of the glass fiber membranes contained only traces of Si4+ and Ca2+ and less than 2 mg/100 ml of nonvolatile matter. No broken or loose fibers were found in the filters. Scanning electron microscopy showed that the web structure of the glass fiber membranes was instrumental in trapping and holding leukocytes. CONCLUSION: A filter made of glass fiber membranes is effective in leukocyte depletion.

Adenine↗