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Biomedical subjects

Y Sun

Publications and source records attributed to Y Sun.

At least 181 records · Page 10Linked to original sources
PubMed2001

Simultaneous determination of phenolic xenoestrogens by solid-phase extraction and high-performance liquid chromatography with fluorescence detection.

A highly sensitive and selective method for simultaneous determination of some hydroxyl group-containing endocrine disruptors, including bisphenol A (BPA), bisphenol B (BPB), bisphenol E (BPE), bisphenol F (BPF) and 4-nonylphenol (4-NP), was developed. The method consists of precolumn derivatization of the analytes, solid-phase extraction (SPE) and subsequent chromatographic analysis by high-performance liquid chromatography (HPLC) with fluorescence detection. 4,4'-Cyclohexylidenebisphenol (BPZ) was used as an internal standard. Derivatization was carried out using 4-(4,5-diphenyl-1H-imidazol-2-yl)benzoyl chloride (DIB-Cl) as a label. Parameters of the derivatization reaction (temperature, time, concentration of reagent, stability, etc.) and of the solid-phase extraction (recovery, solvent, etc.) were studied in detail. Detection limits of compounds studied in standard solutions ranged from 0.08-1.3 ppb (ng/ml). The proposed method was successfully applied to plastic samples; BPA was found in both polycarbonate and polyvinyl chloride plastics, while 4-NP was found in plastics made of polyvinyl chloride and another polymer.

Benzhydryl Compounds↗
PubMed2001

Tissue inhibitor of metalloproteinase-1 prevents cytokine-mediated dysfunction and cytotoxicity in pancreatic islets and beta-cells.

In addition to inhibiting matrix metalloproteinase-2 and matrix metalloproteinase-9 activity, recent studies suggest that tissue inhibitor of metalloproteinase (TIMP)-1 may inhibit apoptosis in various cell lines. To address this question in pancreatic islets and beta-cells, we treated rat pancreatic islets and INS-1 cells with a high-dose combination of the cytokines interleukin (IL)-1beta, tumor necrosis factor-alpha, and interferon-gamma with or without the addition of TIMP-1 and TIMP-2 protein. Using flow cytometry, we quantitated DNA fragmentation to assess cellular apoptosis and confirmed these observations with DNA laddering experiments. Next, we transfected the mouse TIMP-1 gene into INS-1 cells and performed Western immunoblotting to demonstrate expression of TIMP-1 protein. We treated TIMP-1-expressing INS-1 cells with high-dose cytokines and again used flow cytometry to assess DNA fragmentation. We also evaluated the effect of TIMP-1 on IL-1beta-induced inhibition of glucose-stimulated insulin secretion (GSIS) in freshly isolated rat pancreatic islets. Finally, we evaluated the effect of TIMP-1 on inducible nitric oxide synthase (iNOS) gene expression and nuclear factor (NF)-kappaB activity in INS-1 cells stimulated with high-dose cytokines. TIMP-1 but not TIMP-2 prevented cytokine-induced apoptosis and cytokine-mediated inhibition of GSIS in rat islets and beta-cells. TIMP-1 mediated these effects by inhibiting cytokine activation of NF-kappaB, but it did not affect nitric oxide production or iNOS gene expression. Therefore, TIMP-1 may be an ideal gene to prevent cytokine-mediated beta-cell destruction and dysfunction in models of type 1 diabetes and islet transplantation rejection.

Animals↗
PubMed2001

Effects of Mannheimia haemolytica leukotoxin on apoptosis and oncosis of bovine neutrophils.

OBJECTIVE: To investigate the concentration-dependent effects of Mannheimia haemolytica (formerly Pasteurella haemolytica) leukotoxin (LKT) on apoptosis and oncosis in bovine neutrophils and to examine the role of calcium ions (Ca2+) in LKT-induced apoptosis. SAMPLE POPULATION: Neutrophils isolated from blood samples obtained from healthy calves. PROCEDURE: Neutrophil suspensions were exposed to lytic or sublytic dilutions of LKT and then examined by use of transmission electron microscopy (TEM) or gel electrophoresis. Contribution of extracellular Ca2+ to LKT-induced apoptosis was investigated by incubating neutrophils with LKT or control solutions in buffer containing 1 mM CaCl2 or in Ca2+-free buffer containing 1 mM ethylene glycol-bis (b-aminoethyl ether)-N,N-tetraacetic acid (EGTA) prior to diphenyl amine analysis. RESULTS: Examination by TEM revealed that bovine neutrophils exposed to lytic dilutions of LKT had changes consistent with oncosis, whereas neutrophils exposed to sublytic dilutions of LKT and staurosporin, an inducer of apoptosis, had changes consistent with apoptosis. Effects of sublytic dilutions of LKT on apoptosis were confirmed by gel electrophoresis. Replacement of extracellular Ca2+ with EGTA, a Ca2+ chelator, reduced apoptosis attributable to the calcium ionophore A23187, but it did not have significant effects on apoptosis induced by LKT or staurosporin. CONCLUSIONS AND CLINICAL RELEVANCE: The ability of LKT to cause apoptosis instead of oncosis is concentration-dependent, suggesting that both processes of cell death contribute to an ineffective host-defense response, depending on the LKT concentration in pneumonic lesions. Furthermore, although Ca2+ promotes A23187-induced apoptosis, it is apparently not an essential second messenger for LKT-induced apoptosis.

Animals↗
PubMed2001

Effects of different durations of pretreatment with losartan on myocardial infarct size, endothelial function, and vascular endothelial growth factor.

A previous study by our group showed that 10 weeks of pretreatment with losartan reduced myocardial infarct size and arrhythmias in a rat model of ischaemia-reperfusion. However, the effect of a differing time course of pretreatment has not been investigated. 104 Sprague-Dawley rats were randomised to four groups: a control, and three treatment groups in which losartan (40 mg/kg/day) was administered in drinking water for one day, one week, and four weeks respectively. After different durations of pretreatment, the rats were subjected to 17 minutes of left coronary artery occlusion and 120 minutes of reperfusion. Haemodynamic variables were not significantly different between the four groups. Myocardial infarct size was unchanged after one day and one week of pretreatment (52+/-7, 57+/-6% vs.control 55+/-3%), but was significantly reduced by four weeks of pretreatment with losartan (38+/-6, p<0.05). Endothelial-dependent vasorelaxation was significantly increased by four weeks of pretreatment (-81+/-4 vs.-62+7%, p<0.05). As an indicator of ischaemia, vascular endothelial growth factor (VEGF) levels in ischaemic myocardium were decreased after one and four weeks of pretreatment (0.75+/-0.05, 0.58+/-0.10 vs. 1.0, p<0.05,0.01, respectively). In conclusion, losartan has time-dependent cardiovascular protective effects. Four weeks of pretreatment with losartan decreased infarct size and VEGF, and improved endothelial dysfunction.

Angiotensin II↗
PubMed2001

Elevated expression of SAG/ROC2/Rbx2/Hrt2 in human colon carcinomas: SAG does not induce neoplastic transformation, but antisense SAG transfection inhibits tumor cell growth.

Sensitive-to-apoptosis gene (SAG)/regulator of cullins (ROC)2/Rbx2/Hrt2 is a newly identified component of SCF E3 ubiquitin ligase that controls cell-cycle progression by promoting ubiquitination and degradation of cell-cycle inhibitors. We recently found that SAG protects cells from apoptosis induced by redox agents, promotes S-phase entry and cell growth under serum starvation, and is required for yeast growth. In the present study, we report that the SAG protein level was elevated in six of 10 human colon carcinoma tissues (60%) as compared with adjacent normal tissues from the same patient. SAG overexpression in preneoplastic cells in a JB6 tumor promotion-and-progression model did not induce neoplastic transformation, and SAG overexpression in NIH/3T3 cells did not induce transforming foci formation, suggesting that SAG is not a dominant oncogene. However, when DLD-1 human colon carcinoma cells were transfected with antisense SAG, monolayer growth was significantly inhibited, as shown by a decreased number of stable colonies in the plate after normalization with transfection efficiency. Stable clones that expressed antisense SAG showed a 50% decrease in their ability to form colonies when grown in soft agar versus clones that did not express antisense SAG. We found an inverse correlation in four of 10 tumors between the levels of SAG and p27, a cyclin-dependent kinase inhibitor. We concluded that SAG is not causally related to cellular transformation, but its overexpression may be important for the maintenance of tumor cell phenotype. Therefore, targeting SAG expression may have therapeutic value in cancer treatment. Mol. Carcinog. 30:62-70, 2001.

Animals↗
PubMed2001

[The bindings of typical aldehydes pollutants with cell DNA].

The bindings of 3 kinds of aidehyde pollutants, formaldehyde, acetaldehyde, acrolein, with both prokaryotic and eukaryotic DNA, and their genotoxic effect and mechanism were conducted by the shifts of maximum UV absorption peak to determine binding effects and by HPLC to determine binding sites in vitro model system. The shifts of maximum UV absorption peak of prokaryotic DNA contaminated by 3 kinds of aldehyde pollutants are not significant; but after the DNA extracted from prokaryotic bacteria reacting with formaldehyde in tube, the shifts of maximum UV absorption peak of DNA are significant; the shifts of maximum UV absorption peak of eukaryotic DNA contaminated by 3 kinds of aldehyde pollutants are significant also. The reacition of acetaldehyde with dG reduced by NaBH4 was separated and detected by HPLC, the product was determined qualitatively as N2-ethaldeoxyguanosine adduct. The 3 kinds of aldehyde pollutants could bind with cellular DNA to express genotoxic effects; and the N2 site of deoxyguanosine is the possible covalent binding site.

Acetaldehyde↗
PubMed2001

[A preliminary study on the organic carbon weathering fluxes in Beijiang River drainage].

Riverine water samples were collected from Hekou hydrometric station of Beijiang River in five hydrological seasons. The samples were analyzed of their organic carbon and total suspended substance, which demonstrated that the concentrations of particulate organic carbon (POC) changed synchronically with the concentrations of total suspended substance (TSS) in riverine water. The correlation between the concentrations of TSS and dissolved organic carbon (DOC), however, is sometimes positive and sometimes negative, and the correlation is not so notable as that between TSS and POC. With the concentration of total suspended substances increasing, the quality partition of organic carbon in total suspended substance decreased in a logarithm tendency. The transportation of organic carbon, especially of DOC, mainly takes place in flood peak periods. The weathering flux of organic carbon in Beijiang River drainage basin is about 10.01 x 10(6) g.km-2.a-1, which is constituted by 6.54 x 10(6) g.km-2.a-1 of POC and 3.47 x 10(6) g.km-2.a-1 of DOC. This pattern of organic carbon weathering flux in Beijiang drainage basin is consistent with that of most of the monsoon drainage basins.

Carbon↗
PubMed2001

Augmented stretch activated adenosine triphosphate release from bladder uroepithelial cells in patients with interstitial cystitis.

PURPOSE: Extracellular adenosine triphosphate (ATP) has been shown to mediate inflammation and nociception and, therefore, it may have a role in symptoms associated with interstitial cystitis. We theorized that the bladder uroepithelium releases ATP in response to stretch and, furthermore, this process is augmented in interstitial cystitis. MATERIALS AND METHODS: We quantitated ATP using the luciferin-luciferase assay. Urinary ATP levels were compared in 35 patients with interstitial cystitis and in 33 normal controls after pH correction. Cultured interstitial cystitis and normal urothelial cells from the bladder biopsies of 5 patients each were stretched with the Flexcell 2000 machine (Flexcell International Corp., McKeesport, Pennsylvania) and supernatant ATP concentrations were measured. RESULTS: Mean urinary ATP plus or minus standard error of mean was significantly higher in patients with interstitial cystitis than in controls (L value 985 +/- 161 versus 377 +/- 27, p = 0.0007). Supernatant ATP released by stretched interstitial cystitis cells was stretch intensity dependent when comparing 0%, 10% and 20% elongation, and was also significantly higher in stretched interstitial cystitis than in stretched normal cells. CONCLUSIONS: Adenosine triphosphate was significantly elevated in the urine of individuals with interstitial cystitis and the stretch activated release of ATP was augmented in interstitial cystitis urothelium. Increased extracellular ATP may have a role in mechanosensory transduction and to our knowledge it represents a novel hypothesis.

Adenosine Triphosphate↗
PubMed2001

[Quantitative assay of metabolic rate of para-aminobenzoic acid combining glycine for the assessment of rabbit liver function].

OBJECTIVE: To evaluate liver function by the assessment of the capacity of glycine combining para-aminobenzoic acid (PABA) to form hippuric acid in rabbits with acute liver injury. METHODS: Thirty rabbits were randomly divided into two groups: experiment group (n=20) received D-galactosamine to be subject to acute liver necrosis, and control group (n=10) received saline as placebo. Serum concentrations of PABA, para-aminohippuric acid (PAHA), para-acetamidobenzoic acid (PAABA), and para-acetamidohippuric acid (PAAHA) were measured by high pressure liquid chromatography (HPLC). RESULTS: Compared with control group, the serum concentrations of PAHA and PAAHA were significantly reduced in experimental group, which were correlated with the degree of liver injury. CONCLUSIONS: The metabolic rate of glycine combining PABA is a sensitive index for quantitative test of liver function and assessment of acute liver necrosis.

4-Aminobenzoic Acid↗
PubMed2001

The investigational new drug XK469 induces G(2)-M cell cycle arrest by p53-dependent and -independent pathways.

PURPOSE: XK469 (2-[4-(7-chloro-2-quinoxalinyloxy) phenoxy]propionic acid), a synthetic quinoxaline phenoxypropionic acid derivative, has broad activity against murine tumors and is entering Phase I clinical development as a topoisomerase IIbeta inhibitor. This study investigated the underlying molecular mechanism of XK469's effects on the cell cycle. EXPERIMENTAL DESIGN: Growth inhibition, cell cycle arrest, induction of p53 and p21 mRNA and protein, and cdc2 phosphorylation and kinase activity were studied in treated cells from the H460 lung cancer line and p21 and p53 knockout cells of the HCT 116 colon cancer line. RESULTS: XK469 arrested H460 cells at G(2)-M, which was associated with cdc2 phosphorylation and decreased cdc2 kinase activity. Moreover, XK469 stabilized p53 and subsequently increased p21(WAF1/CIP1). Furthermore, HCT116 p21(-/-) cells were less sensitive than wild-type cells to XK469-induced growth inhibition, but p53(+/+) and p53(-/-) cells were equally sensitive despite the absence of p21 induction in the p53(-/-) cells. CONCLUSIONS: When considered with published data, our study suggests a complex mechanism of XK469-mediated anticancer activity involving multiple pathways, including p53-dependent and -independent G(2)-M arrest via inactivation of cdc2-cyclin B1 kinase activity.

Antineoplastic Agents↗
PubMed2001

[Study on the expression of Fas ligand on the surfaces of human cytotrophoblasts in normal pregnancy].

OBJECTIVE: To further study the mechanism of maternal-fetal immune tolerance. METHODS: Chorioplacental tissues were obtained from different gestation stages of normal pregnancy. Immunohistochemistry was used to investigate the expression of Fas Ligand (FasL) on the surfaces of human cytotrophoblasts. Highly precise color-image measure system for immuno-histochemistry was used for quantitative analysis. RESULTS: FasL were expressed on the surfaces of placental cytotrophoblasts throughout normal pregnancy. FasL staining areas on cytotrophoblasts of the first trimester, second trimester and term were (91.410 +/- 8.328) micron 2, (101.322 +/- 11.480) micron 2 and (97.461 +/- 10.517) micron 2 respectively; Average brightness FasL staining were 0.227 +/- 0.0325, 0.261 +/- 0.021, 0.145 +/- 0.015; and integral brightness were 21.391 +/- 4.636, 25.993 +/- 6.231, 18.588 +/- 3.897 respectively. The differences among the first, second and term pregnancy stages were significant. CONCLUSIONS: Like many immune-privileged sites, the maternal specific fas+ T cell apoptosis induced by FasL on the maternal-fetal interface might be one of the significant mechanisms of maternal-fetal immune tolerance. The expression of FasL on the surfaces of placental cytotrophoblasts plays an important role both in the maintenance of pregnancy and in the normal development of fetus.

Adult↗
PubMed2001

[The relationship of variability of blood pressure with cardiac structure and functions in hypertension].

OBJECTIVE: To study the relationship of variability of blood pressure with cardiac structure and functions in essential hypertension. METHODS: A hundred and ten patients suffered from essential hypertension were divided into two groups according whether having left ventricular hypertrophy. The characteristics of overload and variability of blood pressure in both groups were analysed and several indexes on cardiac structure and function were compared between two groups. RESULTS: Both groups showed significant differences in the mass of left ventricle (LVM), the mass index (LVMI) of left ventricle, the thickness of interventricular septum (IVS), posterior wall of left ventricle (LVPW) and relative wall thickness (RWT) except for hypertensive ages. The ratio of E/A in both groups was significantly decreased. The rate of SBP load (SBPLO) both at day and night, the level of SBP in 24 hours and reductive rate of SBP at night (nSBPrr), the variabilities of systolic blood pressure (SBPV) and mean arterial pressure (MAPV) as well as hypertensive vascular overload index (HTNVOI) in two groups were obviously different. CONCLUSIONS: 1) In early stage, the diastolic cardiac function in essential hypertension was damaged. 2) The happeness of left ventricular hypertrophy in essential hypertension was not only associated with the degrees and types of vascular overload, the increased variabilities of systolic blood pressure and mean arterial pressure, reversely with the reductive rate of SBP at night as well, but feebly with hypertensive-age. 3) As a low awareness, hypertensive-age was unreliable in the recollection. 4) Age was also a risk factor of left ventricular hypertrophy in essential hypertension.

Adult↗
PubMed2001

Chemo- and radio-protective effects of polysaccharide of Spirulina platensis on hemopoietic system of mice and dogs.

AIM: To observe polysaccharide of Spirulina platensis (PSp) on the hematopoietic system of mouse and dogs which were damaged by injection of cyclophosphamide (CTX) and 60Co-gamma irradiation. METHODS: CTX and 60Co gamma ray were used to induce bone marrow damage, and the experimental animals were ig with different dose of PSp in vivo, after 12-d and 21-d administration, the whole blood cells and nucleated cells in bone marrow were measured, and the DNA in bone marrow were inspected by UV-spectrophotometer. RESULTS: CTX and 60Co-gamma irradiation induced hemopoietic system damage in mice and dogs, respectively. PSp 30, 60 mg/kg increased the level of the white cells in blood and nucleated cells and DNA in bone marrow in mice but had no effects on red cells and hemoglobins. PSp 12 mg/kg increased the level of red cells, white cells, and hemoglobins in blood and nucleated cells in bone marrow in dogs (P < 0.01), and the effects of PSp 60 mg/kg were better than that of berbamine hydrochloride 60 mg/kg. CONCLUSION: PSp has chemo-protective and radio-protective capability, and may be a potential adjunct to cancer therapy.

Animals↗
PubMed2001

[Rapid detection of Mycobacterium tuberculosis resistance to rifampin using DNA chip].

OBJECTIVE: To develop a new method, DNA chip, which can be used for rapid detection of Mycobacterium tuberculosis resistance to RFP. METHODS: Designing probe according to the sequence of Mycobacterium tuberculosis rpoB gene and fabricating DNA chip. The DNA fragment which contains hot mutation sites of rpoB gene was labelled with cy5 fluorescence and amplified by PCR technique. Then it was hybridized with DNA chip. DNA sequence was used as the control. RESULTS: 14 strains were detected out of 17 randomly selected Mycobacterium tuberculosis resistant to RFP using DNA chip. The efficiency was 83%. A little bit DNA in the sick sputa was sufficient for drug resistance detection without being incubated. CONCLUSION: It showed higher specialty and sensitivity using DNA chip to detect Mycobacterium tuberculosis resistance to RFP. This method was rapid and accurate and could be used for clinical detection of RFP-resistant strains.

Antibiotics, Antitubercular↗
PubMed2001

[Pictures of channel system in Isimpo (Prescriptions of medical heart].

Pictures of channel system in Isimpo (Prescriptions of Medical Heart) was the earliest illustrations of channels. It was of important reference value for the researches on the running courses of channels, confirmation of some points, including Sanyinjiao, Dadu, Taibai and Gongsun, and its orders etc.

Chin↗
PubMed2001

[Detection of BCL2 translocation in an interphase neucleus using fluorescence in situ hybridization strategy].

OBJECTIVE: To establish a specific method to diagnose non-Hodgkin's lymphoma in clinic. METHODS: Fluorescence in situ hybridization (FISH) strategy capable of detecting t(14;18)(q32;q21) chromosome translocation in an interphase nucleus was developed using a YAC clone containing the BCL2 gene and a phage clone containing IgHC(mu) region as probes. In the SU-DHL-6 cells, the translocated BCL2 allele (red) is overlapped by one of the green signals from IgH phage probe, while in normal lymphocytes the least distance of the hybridization signals from two different probes was either equal or larger than one-tenth of the diameter of a nucleus. RESULTS: Based on the relative position of the signals from BCL2 and IgH probes the BCL2 translocation can be clearly detected in an interphase nucleus. The metaphase number and quality in samples, which could significantly restrict the reliability of cytogenetic analysis, can be ignored here. CONCLUSION: This method shows a potentiality in clinical diagnosis of non-Hodgkin's lymphoma because of its objectivity, reliability and simplicity.

Cell Nucleus↗
PubMed2001

Effect of ipratropium bromide on airway and pulmonary muscarinic receptors in a rat model of chronic obstructive pulmonary disease.

OBJECTIVE: To observe the level of muscarinic receptors in airway and lung tissues, and the effect of inhaled ipratropium bromide on these receptors in a rat model of chronic obstructive pulmonary disease (COPD). METHODS: This model was developed by exposure of rats to 250 ppm SO2 gas, 5 h/d, 5 d/wk, for a period of 7 wk. The COPD rats inhaled 0.025% aerosolized iratropium bromide for 20 min, 2 times daily, in an airtight chamber. Muscarinic receptors in airway and lung tissues of normal rats, ipratropium bromide-treated COPD rats and the recovering COPD rats were measured by the radio-ligand binding assay. RESULTS: Airway/lung pathology and pulmonary function tests showed that chronic SO2 exposure caused pathophysiologic changes similar to those observed in human COPD. The density (0.038 +/- 0.011, pmol/mg protein) and affinity (Kd, 23 +/- 11 pmol/L) of muscarinic receptors in airway and lung tissues of COPD rats were not changed compared with those of normal control rats (0.030 +/- 0.008 and 29 +/- 19, respectively, P > 0.05). Densities of the muscarinic receptors were not changed after inhalation of ipratropium bromide for 5 days, but increased significantly after inhalation for 30 days, as compared with those of the untreated COPD rats. The muscarinic receptors returned the normal levels at day 6 after cessation of ipratropium bromide treatment. There were no differences among different groups of rats in equilibrium dissociation constants (Kd). CONCLUSION: A rat model of COPD with pathophysiologic changes similar to the human counterpart was developed using chronic SO2 exposure. There was no significant change in the number and function of muscarinic receptors in airway and lung tissues of the COPD rats, but upregulation of the muscarinic receptors was observed after long-term inhalation of ipratropium bromide.

Animals↗