Biomedical subjects

Wei Song

Publications and source records attributed to Wei Song.

68 records · Page 4Linked to original sources

PubMed2003

[Study of susceptibility and genotype characterization of plasmid-mediated class I cephalosporinase in gram-negative bacteria].

OBJECTIVE: To investigate the susceptibility and genotype characteristics of gram-negative bacteria producing plasmid-mediated class I cephalosporinase (AmpC beta lactamase) epidemic in Southern China. METHODS: A total of 1,187 clinical isolates of nonrepetive gram-negative bacteria were collected from different cities in Southern China. AmpC beta lactamase producing isolates were identified by cefoxitin three-dimensional test, and antimicrobial susceptibility test was identified by Kirby-Bauer agar diffusion test; plasmid conjugation, plasmid extraction, universal PCR for gene amplication of corresponding group was done, and the PCR products were sequenced subsequently. RESULTS: The positive rate of cefoxitin three-dimensional test in gram-negative bacteria was 5.9% (70/1,187), and the prevalence of plasmid-mediated AmpC beta lactamase was: E. coli: 4.2% (19/451), Klebsiella: 4.7% (16/339), Enterobacter: 2.1% (4/190), Alcaligenes: 5.3% (1/19), Acinetobacter: 2.2% (1/45) and the total positive rate was: 3.5% (41/1,187). The susceptibility test showed that compared with the clinical isolates, the transconjugations remained resistance to cephamycins and ampicillin, and susceptible to cefepime and imipenem. PCR amplication and sequencing confirmed them to be bla(DHA-1) gene and bla(ACT-1) gene, and they were mainly distributed in Klebsiella and Escherichia. CONCLUSIONS: DHA-1 and ACT-1 were the most common genotypes in plasmid-mediated AmpC beta-lactamase produced by clinical isolates in Southern China. Fourth-generation cephalosporins and carbapenems could be better choices for the treatment of infection caused by AmpC betalactamase producers.

Bacterial Proteins↗

PubMed2003

[A preliminary study of reducing bleeding procedure during endoscopic sinus surgery].

OBJECTIVE: To explore the method and the feasibility of reducing bleeding procedure(RBP) during endoscopic sinus surgery. METHOD: The focuses and tissue being removed in nasal cavity were coagulated by bipolar radiofrequency in order to reduce bleeding during operation in 53 patients with nasal disease. The bleeding places were coagulated in the same way after operation. RESULT: The nasal cavities without stuffed qauze to control bleeding after operation was in 37 cases (69.8%) of 53 patients operated. The average volume of bleeding during the surgery was 39.67 ml in 37 patients with chronic sinusitis and nasl polyp. CONCLUSION: The RBP during endoscopic sinus surgery is well worth researching and discussing further.

Adult↗

PubMed2002

Presynaptic regulation of neurotransmission in Drosophila by the g protein-coupled receptor methuselah.

Regulation of synaptic strength is essential for neuronal information processing, but the molecular mechanisms that control changes in neuroexocytosis are only partially known. Here we show that the putative G protein-coupled receptor Methuselah (Mth) is required in the presynaptic motor neuron to acutely upregulate neurotransmitter exocytosis at larval Drosophila NMJs. Mutations in the mth gene reduce evoked neurotransmitter release by approximately 50%, and decrease synaptic area and the density of docked and clustered vesicles. Pre- but not postsynaptic expression of normal Mth restored normal release in mth mutants. Conditional expression of Mth restored normal release and normal vesicle docking and clustering but not the reduced size of synaptic sites, suggesting that Mth acutely adjusts vesicle trafficking to synaptic sites.

Action Potentials↗

PubMed2002

Development of heart failure and congenital septal defects in mice lacking endothelial nitric oxide synthase.

BACKGROUND: Nitric oxide (NO) produced by endothelial NO synthase (eNOS) plays an important role in the regulation of cell growth, apoptosis, and tissue perfusion. Recent studies showed that mice deficient in eNOS developed abnormal aortic bicuspid valves. The aim of the present study was to additionally investigate the role of eNOS in heart development. METHODS AND RESULTS: We examined postnatal mortality, cardiac function, and septum defects in eNOS(-/-), eNOS(+/-), and wild-type mice. Postnatal mortality was significantly increased in eNOS(-/-) (85.1%) and eNOS(+/-) (38.3%) compared with wild-type mice (13.3%, P<0.001). Postmortem examination found severe pulmonary congestion with focal alveolar edema in mice deficient in eNOS. Heart shortening determined by ultrasound crystals was significantly decreased in eNOS(-/-) compared with wild-type mice (P<0.05). Congenital atrial and ventricular septal defects were found in neonatal hearts. The incidence of atrial or ventricular septal defects was significantly increased in eNOS(-/-) (75%) and eNOS(+/-) (32.4%) neonates compared with those of the wild-type mice (4.9%). At embryonic days 12.5 and 15.5, cardiomyocyte apoptosis and myocardial caspase-3 activity were increased in the myocardium of eNOS(-/-) compared with wild-type embryos (P<0.01), and increases in apoptosis persisted to neonatal stage in eNOS(-/-) mice. CONCLUSIONS: Deficiency in eNOS results in heart failure and congenital septal defects during cardiac development, which is associated with increases in cardiomyocyte apoptosis. Our data demonstrate that eNOS plays an important role in normal heart development.

Animals↗

PubMed2002

Regulation of lipoprotein lipase by protein kinase C alpha in 3T3-F442A adipocytes.

Lipoprotein lipase (LPL) is an important enzyme in adipocyte and lipid metabolism with complex cellular regulation. Previous studies demonstrated an inhibition of LPL activity and synthesis following depletion of protein kinase C (PKC) isoforms with long term treatment of 3T3-F442A adipocytes with 12-O-tetradecanoylphorbol-13-acetate. To identify the specific PKC isoforms involved, we treated cells with antisense oligonucleotides that block expression of specific PKC isoforms. An antisense oligonucleotide to PKC alpha inhibited LPL activity by 78 +/- 8%, whereas antisense oligonucleotides directed against PKC delta or PKC epsilon had no effect on LPL activity. The change in LPL activity was maximal at 72 h and was accompanied by a decrease in LPL protein and LPL synthetic rate but no change in LPL mRNA, suggesting regulation at the level of translation. However, PKC depletion resulted in no change in the polysome profile, indicating that translation initiation was not affected. However, the addition of cytoplasmic extracts from adipocytes treated with 12-O-tetradecanoylphorbol-13-acetate or PKC alpha antisense oligomers inhibited LPL translation in vitro. This inhibition of LPL translation in vitro was lost when the LPL mRNA transcript did not contain nucleotides 1599-3200, thus implicating the 3'-untranslated region of LPL in the regulation of translation by PKC depletion. Both LPL activity and Raf1 activity were decreased in parallel following depletion of either total PKC or specific inhibition of PKC alpha. An antisense oligonucleotide to RAF1, which inhibited RAF1 activity, also inhibited LPL activity by 48 +/- 10%, and this decrease in LPL activity was not accompanied by a change in LPL mRNA. Cells were treated with U0126, a specific inhibitor of the ERK-activating kinases MEK1 and MEK2. Although U0126 inhibited ERK1 and ERK2 phosphorylation, U0126 had no effect on LPL activity, indicating that MEK/ERK pathways were not involved in this mechanism of LPL regulation. Together, these data indicate that PKC alpha and RAF1 are important in the translational regulation of LPL in adipocytes and that the mechanism of regulation is probably through an ERK-independent pathway.

Adipocytes↗

PubMed2002

The effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on oxidative enzymes in adipocytes and liver.

Reactive oxygen species are produced in response to environmental toxins, and previous studies have suggested that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) damages a number of target organs through the generation of oxygen free radicals and oxidative stress. Upon exposure, TCDD becomes concentrated in adipose tissue, and adversely affects many organs, including liver. This study examined whether oxidative stress was induced in adipocytes and liver that were exposed to TCDD. 3T3-F442A adipocyte cultures were treated with TCDD (5-200 nM) for up to 72 h, and the activity and mRNA levels of superoxide dismutase (SOD), catalase, and glutathione peroxidase (GSH-Px) in adipocyte cell lysates were measured. The addition of 50 nM TCDD induced a two-fold increase in SOD activity after 48 h (P<0.05). In contrast, TCDD had no significant effect on the activity of catalase or GSH-Px in the adipocytes, and the increase in SOD activity was not accompanied by a change in SOD mRNA levels. To assess the effects of TCDD on oxidative stress enzymes in vivo, male Sprague-Dawley rats were injected weekly for 8 weeks with 30 ng/kg TCDD. In addition, the rats were fed either a low-fat complex-carbohydrate (LFCC) diet, or a high fat sucrose diet (HFS). The HFS diet has previously been shown to induce mild obesity and insulin resistance, without inducing diabetes. SOD, catalase, and GSH-Px activities were measured in the liver and adipose tissue of these rats. TCDD injection resulted in a 52% decrease in catalase activity in the adipose tissue of HFS rats (P<0.05). In contrast, SOD and GSH-Px activities were not altered in adipose tissue of TCDD-injected rats. In liver, however, there were significant decreases in GSH-Px activity in response to TCDD. This effect of TCDD was observed in both the LFCC and HFS dietary groups. In addition, GSH-Px activity in the HFS rats was significantly decreased when compared to GSH-Px activity in LFCC rats, in both TCDD-treated and control groups, suggesting that TCDD and a high fat diet may combine to exacerbate oxidative stress. Thus, TCDD induces complex changes in enzymes of oxidative stress in both adipocytes and liver. In adipocytes, these changes occurred post-transcriptionally, as there were no changes in mRNA levels. In addition, a high fat diet per se also resulted in a decrease in GSH-Px activity in liver.

Adipocytes↗

PubMed2002

A tale of two controversies: defining both the role of peroxidases in nitrotyrosine formation in vivo using eosinophil peroxidase and myeloperoxidase-deficient mice, and the nature of peroxidase-generated reactive nitrogen species.

Nitrotyrosine is widely used as a marker of post-translational modification by the nitric oxide ((.)NO, nitrogen monoxide)-derived oxidant peroxynitrite (ONOO(-)). However, since the discovery that myeloperoxidase (MPO) and eosinophil peroxidase (EPO) can generate nitrotyrosine via oxidation of nitrite (NO(2)(-)), several questions have arisen. First, the relative contribution of peroxidases to nitrotyrosine formation in vivo is unknown. Further, although evidence suggests that the one-electron oxidation product, nitrogen dioxide ((*)NO(2)), is the primary species formed, neither a direct demonstration that peroxidases form this gas nor studies designed to test for the possible concomitant formation of the two-electron oxidation product, ONOO(-), have been reported. Using multiple distinct models of acute inflammation with EPO- and MPO-knockout mice, we now demonstrate that leukocyte peroxidases participate in nitrotyrosine formation in vivo. In some models, MPO and EPO played a dominant role, accounting for the majority of nitrotyrosine formed. However, in other leukocyte-rich acute inflammatory models, no contribution for either MPO or EPO to nitrotyrosine formation could be demonstrated. Head-space gas analysis of helium-swept reaction mixtures provides direct evidence that leukocyte peroxidases catalytically generate (*)NO(2) formation using H(2)O(2) and NO(2)(-) as substrates. However, formation of an additional oxidant was suggested since both enzymes promote NO(2)(-)-dependent hydroxylation of targets under acidic conditions, a chemical reactivity shared with ONOO(-) but not (*)NO(2). Collectively, our results demonstrate that: 1) MPO and EPO contribute to tyrosine nitration in vivo; 2) the major reactive nitrogen species formed by leukocyte peroxidase-catalyzed oxidation of NO(2)(-) is the one-electron oxidation product, (*)NO(2); 3) as a minor reaction, peroxidases may also catalyze the two-electron oxidation of NO(2)(-), producing a ONOO(-)-like product. We speculate that the latter reaction generates a labile Fe-ONOO complex, which may be released following protonation under acidic conditions such as might exist at sites of inflammation.

Animals↗

PubMed2002

Inhibition of somatostatin receptor 5-signaling by mammalian regulators of G-protein signaling (RGS) in yeast.

Regulators of G-protein signaling (RGSs) are negative regulators of G-protein coupled receptor (GPCR)-mediated signaling that function to limit the lifetime of receptor-activated G(alpha)-proteins. Here we show that four mammalian RGSs differentially inhibit the activation of a FUS1--LacZ reporter gene by the STE2 encoded GPCR in yeast. In order to examine the role of the GPCR in modulating RGS function, we functionally expressed the human somatostatin receptor 5 (SST(5)) in yeast. In the absence of RGSs, FUS1--LacZ activation in response to somatostatin increased in a dose-dependent manner in cells expressing SST(5). In contrast to the results obtained with Ste2p, all RGSs completely inhibited SST(5)-mediated signaling even at concentrations of agonist as high as 10(minus sign5) M. The ability of RGSs to inhibit SST(5) signaling was further assessed in cells expressing modified Gpa1 proteins. Even though SST(5)-mediated FUS1--LacZ activation was 5-fold more efficient with a Gpa1p/G(i3alpha) chimera, response to somatostatin was completely abolished by all four RGSs. Furthermore, we demonstrate that RGS1, RGS2 and RGS5 have reduced ability to inhibit SST(5)-mediated activation of the RGS-resistant Gpa1p(Gly302Ser) mutant suggesting that the ability to interact with the G(alpha)-protein is required for the inhibition of signaling. Taken together, our results indicate that RGSs serve as better GAPs for Gpa1p when activated by SST(5) than when this G-protein is activated by Ste2p.

Fungal Proteins↗

PubMed2002

Construction of a human immunodeficiency virus type 1 (HIV-1) library containing random combinations of amino acid substitutions in the HIV-1 protease due to resistance by protease inhibitors.

Human immunodeficiency virus type 1 (HIV-1) heterogeneity contributes to the emergence of drug-resistant virus, escape from host defense systems, and/or conversion of the cellular tropism. To establish an in vitro system to address a heterogeneous virus population, we constructed a library of HIV-1 molecular clones containing a set of random combinations of zero to 11 amino acid substitutions associated with resistance to protease inhibitors by the HIV-1 protease. The complexity (2.1 x 10(5)) of the HIV-1 library pNG-PRL was large enough to cover all of the possible combinations of zero to 11 amino acid substitutions (a total of 4,096 substitutions possible). The T-cell line MT-2 was infected with the HIV-1 library, and resistant viruses were selected after treatment by the protease inhibitor ritonavir (0.03 to 0.30 microM). The viruses that contained three to eight amino acid substitutions could be selected within 2 weeks. These results demonstrate that this HIV-1 library could serve as an alternative in vitro system to analyze the emergence of drug resistance and to evaluate the antiviral activity of novel compounds against multidrug-resistant viruses.

Amino Acid Sequence↗

PubMed2002

Effect of N-desulfated heparin on hepatic/renal ischemia reperfusion injury in rats.

AIM: To investigate the effect of N-desulfated heparin on hepatic/renal ischemia and reperfusion injury in rats. METHODS: Using rat models of 60 minutes hepatic or renal ischemia followed by 1 h,3 h,6 h and 24 h reperfusion,animals were randomly divided into following groups,the sham operated controls,ischemic group receiving only normal saline,and treated group receiving N-desulfated heparin at a dose of 12 mg/kg at 5 minutes before reperfusion. P-selectin expression was detected in hepatic/renal tissues with immunohistochemistry method. RESULTS: P-selectin expression, serum ALT, AST, BUN and Cr levels were significantly increased during 60 minute ischemia and 1 h, 3 h, 6 h and 24 h reperfusion,while the increment was significantly inhibited,and hepatic/renal pathology observed by light microscopy was remarkably improved by treatment with the N-desulfated heparin. Furthermore,the heparin was found no effects on PT and KPTT. CONCLUSION: P-selectin might mediate neutrophil infiltration and contribute to hepatic/renal ischemia and reperfusion. The N-desulfated heparin might prevent hepatic/renal damage induced by ischemia and reperfusion injury without significant anticoagulant activity.

Alanine Transaminase↗

PubMed2002

Gene cloning of human soluble CD14 and its expression in eucaryotic cells.

OBJECTIVE: To express human soluble CD14 (sCD14) in eukaryotic cells. METHODS: Human sCD14 cDNA was amplified from U937 cells with RT-PCR method. The recombinant expression plasmid pEF1/HisC/sCD14(348aa) was constructed and the expression in COS-7 cells was carried out using liposome transfection method. The yield was examined with scanning map identification. The expressed product was purified by immuno-affinity chromatography. RESULTS: Sequence analysis demonstrated that the amplified gene sequence and those reported by documents were completely identical. sCD14 was expressed with high-yield. The expressed product was purified to above 90%. Recombinant sCD14, specifically combinable with endotoxins, had a natural biological activity. CONCLUSIONS: Human sCD14 was expressed in COS-7 cells, which laid a foundation for further study.

Animals↗

PubMed2002

[Study on the factors in the complications of endonasal sinus surgery].

OBJECTIVE: To investigate the cause of complications occurring in the operations of endonasal sinus surgery(ESS) and how to deal with. METHOD: 526 patients performed with ESS were analyzed. 31 patients had complications. The incidence of the complications in patients operative history was 38.9%, the incidence of bleeding in which the bleeding amount was over 200 ml was 30.2%, the incidence in patients whose medical history was less than 10 years was 2.8%. RESULT: Except for one patient whose eyesight decreased without recovery, the rest recovered. CONCLUSION: The cause of the complications in ESS was related with the destroy of normal structure, sinus bony anatomic variations, amount of intraoperative bleeding and the time of medical history.

Adolescent↗

PubMed2002

[Lipids disorder, macrovascular diseases, and insulin resistance in Chinese diabetic patients].

OBJECTIVE: To investigate the types of lipid disorder and its relationship with macrovascular diseases and insulin resistance in Chinese diabetic patients. METHODS: 2,430 diabetic patients finished the diabetes complications assessment and were surveyed on their blood lipids, insulin level and macrovascular diseases. The insulin resistance (HOMA-IR) was calculated based on HOMA model. RESULTS: Prevalence of lipids disorder was as high as 63.8% in this group, including 23.9% with both hypercholesterolemia and hypertriglyceridemia (HY-C-T), 16.1% with hypercholesterolemia only (HY-C), 15.0% with hypertriglyceridemia only (HY-T), 5.5% with lower HDL level (L-HDL), 3.3% with hypercholesterolemia, hypertriglyceridemia and lower HDL level together. Compared with the patients with normal lipid level (control group), no duration differences existed among these groups. There were more female patients in HY-C and HY-C-T groups. BMI and WHR were higher in all groups with lipid disorder except in HY-C group. Macrovascular diseases were more common in HY-C-T patients than in control group (33.6% vs 24.0%, P < 0.001). Average blood pressure and the prevalence of hypertension were significantly higher in HY-C-T, HY-C, HY-T groups than in control group (139/79, 138/76, 134/77 vs. 132/75 mmHg; 53.2%, 50.1%, 46.2% vs. 39.2%). Fasting insulin level was significantly higher in HY-C-T and HY-C-T-L-LDL groups than in controls. Insulin resistance was more severe in all patients with lipid disorder except in L-HDL group, particularly in the HY-C-T-L-HDL group. CONCLUSIONS: (1) BMI, WHR increased significantly with the severity of lipid disorder. (2) Nearly two thirds of Chinese diabetic patients have lipid disorder, which is the strong risk factor of macrovascular diseases and aggravates insulin resistance. (3) There was severe insulin resistance in patients with hypertriglyceridemia or with hypertriglyceridemia plus other lipid disorder.

Adult↗

PubMedDate not supplied

Characterization of oxidative pathways in chronic rhinosinusitis and sinonasal polyposis.

BACKGROUND: Eosinophils are a characteristic inflammatory cell infiltrate in both chronic rhinosinusitis (CRS) and sinonasal polyposis (SNP). The posttranslational modifications, 3-bromo-tyrosine (Br-Tyr) and 3-chloro-tyrosine (Cl-Tyr), serve as specific molecular markers for production of brominating and chlorinating oxidants, respectively, by the eosinophil peroxidase and myeloperoxidase systems of leukocytes. The aim of this study was to identify mechanisms of oxidative protein modifications in sinonasal mucosa of CRS and SNP patients by measuring Br-Tyr, Cl-Tyr, and alternative molecular markers of distinct oxidative pathways. METHODS: Levels of Br-Tyr; Cl-Tyr; di-Tyrosine (di-Tyr), a specific oxidative cross-link; ortho-tyrosine (o-Tyr) and meta-tyrosine (m-Tyr), markers for protein modification by hydroxyl radical-like oxidants; and nitro-tyrosine (NO2-Tyr), a stable product of nitric oxide (NO)-derived oxidants, were measured in anterior ethmoid mucosa tissue from CRS and SNP patients, as well as in middle turbinate mucosa from normal volunteers, using tandem mass spectrometry. RESULTS: Tissue levels of Br-Tyr were significantly higher in the CRS group compared with the control group (797 micromol/mol versus 515 micromol/mol tyrosine, p < 0.015), but no differences were detected for Cl-Tyr, di-Tyr, m-Tyr, o-Tyr, and NO2-Tyr. Tissue levels of both Br-Tyr and di-Tyr were significantly higher in the SNP group compared with the control group (879 micromol/mol versus 515 micromol/mol, p < 0.005; 5090 micromol/mol versus 1700 micromol/mol, p < 0.024, respectively), but no differences were detected for Cl-Tyr, m-Tyr, o-Tyr, and NO2-Tyr. CONCLUSION: Br-Tyr, a molecular footprint predominantly formed by eosinophil peroxidase-catalyzed tissue damage, may serve as an objective index of CRS and SNP disease activity.

Adult↗