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Biomedical subjects

Y Xu

Publications and source records attributed to Y Xu.

At least 703 records · Page 39Linked to original sources
PubMed1998

[Obtaining transgenic rice plants and their progenies using Agrobacterium tumefaciens].

Rice (Oriza sativa L.) suspension cells of Taipei 309 were co-cultivated with A. tumefaciens stran EHA101 harbouring binary vector pBYT2 for 3 days in the presence of vir inducer, 100 mumol/L acetosyringone (AS). After 2 months of continuous selection, 17 stable hygromycin-resistant, GUS-positive calli were recovered from 364 suspension cell clusters co-cultivated with A. tumefaciens. 10 putative transgenic R0 plants obtained from 8 tansformed calli and their progenies were analyzed for the integration and expression of foreign genes. Southern blot analysis of R0 and R1 generations indicated that foreign genes had been stably integrated in the genome of transgenic rice and sexually transmitted. One of the transgenic lines showed 5 copies of T-DNA integration, while the others had only one copy. Histochemical staining observation and fluorometric assay of GUS activity in transgenic rice cells and plants showed ubiquitin promoter from maize was highly effective in driving the expression of gus reporter gene in transgenic rice cells. GUS protein and its activity were also investigated through ndPAGE-X-Gluc staining assay, and it was found that the GUS protein in transgenic rice cells was smaller in size than the standard GUS protein (Sigma Co. G0786) but as large as that from E.coli HB101 (pBI121). This study suggested that Agrobacterium-mediated transformation of plant is an efficient and reliable method to introduce foreign genes into rice.

Agrobacterium tumefaciens↗
PubMed1998

[Effects of dibutyl phthalate on the proliferation and apoptosis of leukemic cells].

This study was designed to investigate the effects of dibutyl phthalate (DBP) on the proliferation and apoptosis of leukemic cells. The results showed that DBP suppressed the proliferation of HL-60 and K562 leukemic cells in a dose-dependent and time-dependent manner. Inducing HL-60 and K562 leukemic cells to die via apoptosis were confirmed by that the percentage of the apoptotic cells in morphology and of the DNA fragmentation increased significantly and that typical ladders of apoptosis were shown by gel electrophoresis when HL-60 and K562 cells were exposed to the DBP. Also, K562 leukemic cells was less susceptible to the DBP than HL-60 cells. These results indicate that DBP can inhibit the proliferation of HL-60 and K562 leukemic cells and induced them to die via apoptosis.

Antineoplastic Agents↗
PubMed1998

[Detection of sister chromatic exchange in workers exposed to coal tar pitch and to coke oven volatiles].

In order to know the changes of genetic toxicological effects on workers occupationally exposed to polycyclic aromatic hydrocarbons (PAHs), sister chromatic exchange(SCE) was detected by the methods of peripheral lymphocyte culture in 23 workers exposed to coal tar pitch (CTP) and in 19 workers exposed to coke oven volatiles (COV) and 12 normal controls. The results suggested that the SCE in occupational workers was significantly higher than that in controls (11.31 vs 6.37, P < 0.001). The SCE in workers exposed to CTP and to COV was higher than that of control (10.27 and 12.58 vs 6.37) respectively. In workers exposed to CTP and COV, there were no differences of SCE for smokers and nonsmokers (P > 0.05). It is indicated that CTP and COV caused strong genetic toxicity and injury to chromosome.

Adult↗
PubMed1998

[Efficacy of beta-carotene on lipid peroxidation induced by N-nitrosodimethylamine in rats].

The effect of beta-carotene (beta-C) on lipid peroxidation induced by N-nitrosodimethylamine (NDMN) in rats was studied. Thirty clear conventional SD rats were randomly devided into 3 groups and were intragastricly given daily water (10 ml/kg). NDMN (1.75 mg/kg), and NDMN (1.75 mg/kg) plus beta-C (25 mg/kg) respectively. The results showed that: compared with group 1, the activities of SOD and GSH-Px in NDMN group were significantly decreased (P < 0.05), the values of MDA and ROOH increased (P < 0.05). The activities of SOD and GSH-Px in group 3 were significantly higher and the contents of ROOH and MDA were significantly lower than that of NDMN group (P < 0.05). These results suggested that free radicals and lipid peroxidation may be a carcinogenic path for NDMN and other nitrosamines. beta-C had ability to inhibit the lipid peroxidation induced by NDMN.

Animals↗
PubMed1998

[Genetic epidemiological study of asthma in general].

With theory and method of genetic epidemiology, data of 641 nuclear families on asthma were analysed, and the results showed that the history of parents asthma was one of risk factors about offsprings asthma, and the risk was 4.0-8.0 times higher (P < 0.01), compared with the one of offsprings of parents with no asthma. The effect of parents with asthma on the risk of sons was the same as one of daugters. The result declared that the airway responsiveness of parents did not relate to the one of offsprings. The results suggest that the genetic factors play an important role in the asthma.

Adolescent↗
PubMed1998

[Comparison of the effects of inhaled nitric oxide and intravasculare regitine on pulmonary gas exchange in young dogs with oleic-acid acute lung injury].

In order to find an agent which truly improves hypoxemia of some serious pediatric lung diseases, the authors examined the independent effects of nitric oxide inhalation and regitine infusion on blood gases, intrapulmonary shunt and hemodynamics in young dogs with oleic-acid acute lung injury. After nitric oxide inhalation, the results showed moderate increases in PaO2 and SaO2 (P > 0.05) and a significant decrease in Qs/Q tau ratio (P < 0.01). There was a significant decrease of PAP(P < 0.05), while SAP remained unchanged. After regitine infusion, however, there were marked decreases in PaO2 and SaO2 (P < 0.01); meanwhile, Qs/Q tau rose (P < 0.05). These suggest that with the presence of pulmonary pathology nitric oxide inhalation may alleviate the elevated pulmonary pressure without alteration in systemic artery pressure; so it can improve pulmonary ventilation-perfusion distribution and cause favorable changes in blood gases. On the other hand, regitine, as a non-selective vasodilator, reduces pulmonary artery pressure at the cost of significant worsening of blood oxygenation and systemic hypotension; so its routine use in childhood pulmonary diseases should be cautiously considered.

Animals↗
PubMed1998

[The source of endogenous digitalis-like substance in normal pregnancy].

OBJECTIVE: To study the source of endogenous digitialis-like substance (EDLS) which increases in maternal vein plasma during normal pregnancy. METHODS: The EDLS concentrations in following samples: (1) villi in the 1st trimester (2) placenta, amnion and umbilical jelly of Wharton in the 3rd trimester, (3) plasma of normal non-pregnant women (4) maternal plasma in three trimesters, 24-48 hours post partum, (5) maternal plasma and umbilical blood in labour, were determined by radioimmunoassay. RESULTS: The concentration of EDLS in villi, placenta, amnion and jelly of Wharton was about 37, 33, 29 and 24 times higher respectively than the concentration of maternal blood. There was a significant positive correlation between the concentrations of EDLS in placenta or amnion and that in jelly of Wharton. Plasma EDLS levels in pregnant women of 1st and 2nd trimesters were similar to that in non-pregnant women, while in the 3rd trimester of pregnany they were significantly increased, and then significantly decreased in 24 to 48 hours post partum. There was a significant positive correlation between the plasma EDLS level and mean arterial pressure in the 3rd trimester. The EDLS concentration in plasma of umbilical vein and artery was about 3.1 and 2.9 times higher respectively than that in the maternal plasma. There were significant positive correlations between plasma EDLS levels of umbilical vein, artery or maternal vein and the weight of placenta or newborn. CONCLUSION: The fetal-placenta unit is the source of EDLS which increases in maternal vein plasma during normal pregnancy.

Adult↗
PubMed1998

[Effects of different expression levels of fibronectin on biological behavior of tumor cells].

OBJECTIVE: To study the effects of fibronectin(FN) on tumor cell proliferation, adherence and invasion. METHODS: FN cDNA was introduced into a transitional carcinoma cell line 253J which expressed low level of FN, and 253 FN line which expressed higher level of FN was established. The changes of cellular proliferation in vitro were observed. Adhesiveness to the extracellular matrix was detected by MTT method. Hemotypic adhesion was investigated by detachment assay and invasiveness of the cells was observed with Boyden Chamber before and after FN cDNA gene transfection. RESULTS: The growth rate of 253-FN was decreased as compared with its parental cell 253J. Hemotypic adhesion was significantly increased. The adhesiveness of the cells to extracellular matrix was enhanced. Invasion assay showed that invasioness of 253-FN was decreased. CONCLUSION: This study suggested a correlation between FN expression and its biological behavior. With increased FN level, malignant phenotype was changed and invasive ability was inhibited.

Carcinoma, Transitional Cell↗
PubMed1998

[Apoptosis versus proliferation activities and relative mechanism in chronic obstructive pulmonary disease].

OBJECTIVE: To study the roles of apoptosis and proliferation and relative genes expression in chronic obstructive pulmonary disease (COPD) and pulmonary hypertension. METHODS: Immunohistochemical technique was used for the detection of cell proliferation and expression of relative genes. In situ end labeling technique was used for the detection of nucleosomal DNA fragmentation of apoptotic cells, and Northern blot for the detection of expression of c-myc, bcl-2 and p53 genes in the lungs with COPD. RESULTS: Both proliferative cells and apoptotic cells were found in the lungs with COPD or without COPD. In lung tissue with COPD. The proliferation index was increased significantly, whereas the apoptosis index was decreased significantly. Compared with controls, the ratio of proliferation to apoptosis in lungs with COPD was increased by 4 folds, and the expression of c-myc or bcl-2 mRNA was significantly increased by 2.5-3 folds in lungs tissue with COPD. The expression of c-myc and bcl-2 protein was also increased significantly in lungs with COPD, the two antigen were predominantly localized in small pulmonary vessels. The expression of p53 mRNA was significantly decreased by 3 folds in lung tissue with COPD. CONCLUSION: The abnormality of apoptosis versus proliferation activities induced by c-myc, bcl-2 and p53 genes may contribute to pulmonary vascular structural remodeling in COPD.

Apoptosis↗
PubMed1998

[The diagnosis and therapy of tinnitus].

Selection criteria for the therapeutic strategy are provided by a classification on the basis of the following points: 1. can be masked by a sound, 2. response to parenteral lidocaine. This classification was used to treat 119 patients with tinnitus. Masking is the first therapy for tinnitus. If masking had no effect, lidocaine test were undergone. The patient who has a positive response to lidocaine were treated by antiepileptic drugs. Patients with negative response to lidocaine negative were treated by suppressant. The prognosis for patients with positive masking effect was more better than the negative one. The mechanisms of tinnitus were discussed.

Anticonvulsants↗
PubMed1998

[Magnetic resonance imaging of hypopharyngeal and cervical esophageal cancer].

Imaging by MR (MRI) and esophageal barium meal of 17 cases of hypopharyngeal and cervical esophageal cancer were analyzed. The results indicate that esophageal barium meal can not demonstrate the invading of neoplasms to the adjacent structure. Therefore, it is difficult to use the only data of esophageal barium meal for TNM staging. The results also indicate that MRI is more useful and reliable in assessing the three dimensional structure and the neoplasms invading to the adjacent structure. This results suggest that MRI is that useful in determining the diagnosis, TNM staging and the determining the appropriate operative therapy for hypopharyngeal and cervical esophageal cancer.

Adult↗
PubMed1998

[Effects of antisense cyclin D1 expressing vector on the cell growth and apoptosis of pancreatic carcinoma].

OBJECTIVE: To observe the effects of antisense (AS) cyclin D1 expressing vector on the cell growth and apoptosis of pancreatic carcinoma. METHODS: Examination of the amplification and expression of cyclin D1 in 5 human pancreatic carcinoma cell lines. Our study found the gene amplification and overexpression of cyclin D1 in PC-7 cell line cells. We then constructed the antisense cyclin D1 vector and transfected the PC-7 cell line with lipofectin. The resultant transformant cell line, PC-7/AS-cyclin D1, showed the expression of exogenous antisense cyclin D1 mRNA and down regulation of endogenous cyclin D1 mRNA expression and inhibition of its protein synthesis detected by Northern blot and Western blot respectively. RESULTS: The transformant cells showed retardation of cell growth and partial reversion of the malignant phenotype, including decrease of the rates of cell growth, DNA synthesis, cell proliferation and metabolism, and also the ability of soft agar colony-formation. The tumorogenesis of the transformant cells in nude mice was suppressed. G1 arrest was revealed by flow cytometry. Apoptosis was identified by DNA fragmentation and in situ TUNEL detection. CONCLUSION: Down scaling of the expression of cyclin D1, which plays an important role in the regulation of the cell cycle, can effectively inhibit the proliferation of carcinoma cells and increase cell apoptosis.

Apoptosis↗
PubMed1998

Prevention of maternal-fetal blood group incompatibility with traditional Chinese herbal medicine.

OBJECTIVE: To evaluate the effect of traditional Chinese herbal medicine on the prevention of hemolytic disease caused by maternal-fetal blood group incompatibility. METHODS: A total of 126 Chinese patients with maternal-fetal blood group incompatibility were studied, including 105 cases of ABO type and 21 cases of Rh type incompatibility. The traditional Chinese herbal medicine was used for preventative treatment in 79 cases, and 47 cases served as controls. The prescription consisted of Herba leonuri 500 g, white peony root 180 g, Banksia rose 12 g, root of Chinese angelica 150 g and Rhizomal ligustica 150 g. RESULTS: Preventative treatment with traditional Chinese herbal medicine significantly reduced the perinatal mortality rate in cases of Rh type incompatibility, from 50.0% in the control group to 7.7% in the treatment group (P < 0.05). There was no death in the cases of ABO incompatibility. The traditional Chinese herbal medicine also decreased the degree of hemolysis. The percentage of severe cases in the control group was 29.8%, while it was 15.2% in the treatment group (P = 0.05). The duration of treatment was closely related to the outcomes. In patients who used traditional Chinese herbal medicine for more than 10 weeks, the incidence of severe hemolysis was 8.2%, compared with 38.9% in those treated for less than 10 weeks (P < 0.05). The change of serum immune antibody (A and/or B) titers during the treatment was a very important predictive factor for the outcome of the pregnancy. CONCLUSION: Traditional Chinese herbal medicine is effective not only for ABO type but also for Rh type maternal-fetal blood group incompatibility, with no side effects.

ABO Blood-Group System↗
PubMed1998

[A study of the correlations between asthma and airway responsiveness].

OBJECTIVE: To evaluate the effect of airway responsiveness on asthma and to study the causes of asthma. METHODS: The 641 nuclear families were confirmed by indicator cases with asthma in three counties. Investigation and methacholine challenge test were conducted for all relatives of the nuclear families. The data were by EPI5.01 and the odds ratio (OR) was employed to evaluate the correlation between asthma and airway responsiveness. RESULTS: 72 percent of persons with asthma history showed airway hyperresponsiveness, but only 70 per cent of persons with airway hyperresponsiveness suffered asthma. The risk for asthma in relatives with positive airway responsiveness was 5.8 times higher than those with negative airway responsiveness (P > 0.01) among the nuclear families. CONCLUSION: Airway hyperresponsiveness is one of the risk factors of asthma.

Adolescent↗
PubMed1998

[L-arginine prolonged the efficacy of inhaled nitric oxide on the inhibition of pulmonary hypertension].

OBJECTIVE: The aim of this study is to investigate the effects of L-arginine, the substrate of nitric oxide (NO) on the duration of nitric oxide selective decrease of pulmonary hypertension. To assess whether combined use of inhaled nitric oxide and venous administered L-arginine can improve the efficacy of inhaled NO on the inhibition of hypoxia induced pulmonary hypertension. METHOD: Eight pigs with hypoxic pulmonary hypertension received either inhaled NO(12-15 ppm) for 10 minutes or inhaled NO plus venous administrered L-arginine(10 g), then hemodynamic parameters were recorded. RESULT: NO inhalation significantly inhibited hypoxic induced pulmonary hypertension with pulmonary arterial pressure decreasing from 4.2 +/- 0.4 kPa to 2.5 +/- 0.5 kPa(P < 0.01) and pulmonary vascular resistance from 56 +/- 25 kPa.s.L-1 to 31 +/- 13 kPa.s.L-1(P < 0.01), but this just lasted for 3-5 minutes after stopping inhalation; combined use of L-arginine infusion did not further decrease pulmonary arterial pressure, but significantly prolonged the inhibitory effect of inhaled NO on pulmonary hypertension (20 times) as compared with inhaled NO only. CONCLUSION: With the existence of exogenous NO, supplement of NO substrate L-arginine produced a synesgetic inhibition effect on hypoxic induced pulmonary hypertension.

Administration, Inhalation↗
PubMed1998

[Effects of nitric oxide on the airway inflammation and lymphocyte proliferation in sensitized rats].

OBJECTIVE: To investigate the relations between intrinsic nitric oxide (NO) and airway inflammation and lymphocyte proliferation in bronchial asthma. METHOD: The rat model of asthmatic airway inflammation was established by first sensitizing and then challenging the animals with ovalbumin. NO synthase (NOS) inhibitor and NO precursor were then applied and their influences on the airway inflammatory cell numbers and on the numbers of mIL-2R positive lymphocytes were observed. RESULT: In vivo experiments showed that normal control rats (n = 6) did not have eosinophils in their submucosal of airways while in the sensitized animals (n = 6) eosinophils [23 +/- 5 (average cell counts per microscopic visual field, the same below) as well as lymphocytes (34 +/- 5) and mIL-2R positive cells (12 +/- 3) were found in significantly increased numbers in the airways. The application of NOS inhibitor significantly reduced eosinophils (13 + 3, P < 0.05) and mIL-2R positive cells (4.3 +/- 1.6, P < 0.05) in the sensitized animals and the number of lymphocytes was also decreased (28 +/- 4) although it did not reach the significant level. At the same time the spleen cell proliferation was inhibited (P < 0.05) and the mIL-2R positive spleen cell numbers were reduced (P < 0.05). On the contrary, the application of NO precursor resulted in the further increase of the numbers of eosinophils, lymphocytes and mIL-2R positive cells although the differences were not statistically significant. In vitro experiments showed that NOS inhibitor inhibited the proliferation of cultured spleen lymphocytes as well as their mIL-2R expression (P < 0.05). NO precursor, when used in low dose, could promote the proliferation and mIL-2R expression of spleen cells (P < 0.05); but high dose of it showed inhibiting effect on the spleen cells (P < 0.05). CONCLUSION: Intrinsic NO at a suitable level is important in the regulation of the proliferation and activation of lymphocytes in the airways with allergic inflammation in the sensitized rats. This research is conducive to the understanding of the pathogenesis of the asthmatic airway inflammation and to investigating of new therapeutic approaches.

Animals↗
PubMed1998

[The regulating effect of protein kinase C pathway on the airway tone].

OBJECTIVE: To investigate if the role of protein kinase C(PKC) signal pathway in the regulation of tracheal and lung parenchymal strips tone in normal guinea-pigs is different from that in ovalbumin-sensitized ones. METHOD: By measuring the tones of tracheal and lung parenchymal strips isolated from normal and ovalbumin sensitized guinea-pigs, the effects of PKC-specific activator PMA and inhibitor Ro31-8220 were observed and compared. RESULT: (1) PMA caused concentration-dependent relaxations in the tracheal strips of both normal (n = 7) and sensitized animals(n = 7) and the relaxant effects were significantly stronger on the strips from the sensitized animals than on those from the normal ones(P < 0.05). The relaxing effects could be completely inhibited by Ro31-8220. (2) PMA led to concentration-dependent contractions in the lung parenchymal strips and the contractile effects were significantly stronger on the strips from the sensitized animals (n = 5) than on those(n = 6) from the normal ones (P < 0.05). This contractile response could be abolished by Ro31-8220. (3) Ro31-8220 could partly suppress the contractile response of sensitized lung parenchymal strips to in vitro antigen attacks (n = 10, P < 0.01). CONCLUSION: (1) The regulating effects of PKC on airway smooth muscle tone differ in different locations of the guinea-pig airways. (2) The function of PKC signal pathway in airway smooth muscle from sensitized guinea-pig is increased compared with that from normal one. It is suggested that the role of PKC signal pathway may be important in the pathogenesis of asthma.

Animals↗