Biomedical subjects

Ning Xu

Publications and source records attributed to Ning Xu.

At least 55 records · Page 3Linked to original sources

PubMed2004

Transforming growth factor-beta down-regulates apolipoprotein M in HepG2 cells.

Apolipoprotein M (apoM) is a novel apolipoprotein presented mostly in high-density lipoprotein (HDL) in human plasma, and is exclusively expressed in liver and in kidney. The pathophysiological function of apoM has not yet been elucidated. Apolipoprotein B (apoB), the characteristic apolipoprotein of low-density lipoprotein (LDL), is like apoM, a very hydrophobic protein, and thereafter they both must co-circulate with lipoprotein particles in plasma. The cytokine, transforming growth factor-beta (TGF-beta), has been shown to decreased apoB secretion in HepG2 cells, and we hypothesized that TGF-beta may have the same effects on apoM expression in HepG2 cells. In the present study, we used real-time RT-PCR to analyze apoM and apoB mRNA levels during administration of TGF-beta, as well as TGF-alpha, epidermal growth factor (EGF) and hepatic growth factor (HGF). TGF-beta significantly inhibited both apoM and apoB mRNA expression in HepG2 cells. The inhibitory effects of TGF-beta were dose-dependent, i.e. 1 ng/ml of TGF-beta decreased apoM mRNA levels by 30%, and 10 or 100 ng/ml of TGF-beta decreased apoM mRNA levels more than 65%. The effect of TGF-beta on apoB mRNA expression was slightly weaker than that of apoM, with a maximum effect at 10 or 100 ng/ml TGF-beta where apoB mRNA levels decreased about 55%. The inhibitory effects of TGF-beta on apoM and apoB mRNA levels also increased with increasing incubation time, where the maximum effect was obtained at 24 h. Moreover TGF-alpha, EGF and HGF all decreased both apoM and apoB mRNA levels, but to a less extent than TGF-beta. Further, all four cytokines had more pronounced effects on apoM mRNA expression than apoB mRNA expression. The present study suggested that apoM, like apoB, may be involved in the hepatic lipoprotein assembly in vivo.

Apolipoproteins↗

PubMed2004

Expression pattern of apolipoprotein M during mouse and human embryogenesis.

Apolipoprotein M (apoM) is a recently discovered human apolipoprotein predominantly present in high-density lipoprotein (HDL), and in minor proportions in triglyceride-rich lipoprotein (TGRLP) and low-density lipoprotein (LDL). The gene encoding apoM is present in all mammalian genomes. The identity of the apoM gene of human, rat and mouse is over 80%. However, the (patho)physiological functions of apoM are unknown yet. In the present study, we investigated apoM expression patterns during mouse and human embryogenesis. ApoM transcripts were detectable in mouse embryos from day 7.5 to day 18.5. ApoM was expressed at low levels at day 7.5, its expression increased significantly at day 9.7, decreased at day 10.5, and then increased continually up to day 18.5. ApoM-positive cells appeared mainly in liver of day-12 embryos as detected by in situ hybridization. In day-15 embryos, apoM was expressed in both liver and kidney. During human embryogenesis, apoM was mainly expressed in liver and kidney and little was found in small intestine as determined by mRNA array of human fetal normal tissues. ApoM was also detected in stomach and skeletal muscle in early stages of embryogenesis (3-5 months).

Animals↗

PubMed2004

A novel pattern of pp65-positive cytomegalic endothelial cells circulating in peripheral blood from a renal transplant recipient.

The present study reports a novel pattern of cytomegalic endothelial cells (CEC) in peripheral blood from a female renal transplant recipient infected with human cytomegalovirus (HCMV), which has not been reported previously. Localization of specific early antigen of HCMV, pp65 antigen, was examined by immunohistochemistry. Staining of an endothelial cell marker (CD34) was used to characterize endothelial cells. It is demonstrated that many leukocytes surrounded and adhered to a protein-like material, in which pp65-positive CEC were detected. The composition and function of this protein-like material are yet unknown. The patient lacked clinical symptoms of HCMV disease. Furthermore, similar localization patterns were found in other renal transplant recipients suffering from HCMV infections as determined by real-time PCR to detect HCMV DNA in blood. These patients showed no or only minor clinical symptoms of HCMV infection. It is suggested that these novel localization patterns of CEC may play a role in the host defense in patients infected with HCMV, but the exact relation between HCMV infection and CEC formation needs further investigation.

Cytomegalovirus↗

PubMed2004

Correlation of apolipoprotein M with leptin and cholesterol in normal and obese subjects.

Apolipoprotein M (apoM) is a recently characterized apolipoprotein that is exclusively expressed in the liver and kidney. In plasma it is present predominantly in high-density lipoprotein (HDL). The physiological function of apoM is not yet known. In the present study we investigated relationships between plasma apoM levels and leptin levels, body mass index (BMI), as well as fasting glucose and other lipid parameters in women with a wide range of BMI (18.9-57.1 kg/m(2), n = 51). In univariate analysis, apoM correlated significantly with leptin (r = 0.54, P < 0.001), BMI (r = 0,70, P < 0.001), fasting insulin (r = 0.33, P = 0.025), total cholesterol (r = -0.41, P = 0.016), and LDL-cholesterol (r = -0.39, P = 0.018). The correlations between apoM and cholesterol and between apoM and leptin remained significant after adjustment for the influence of BMI. Forward stepwise multiple regressions when leptin, BMI, insulin, and cholesterol were entered into a model as independent variables and apoM as the dependent variable, showed that cholesterol and leptin were independent predictors of circulating apoM. These two parameters yielded a value of r(2) = 0.28, thereby explaining approximately 30% of the variance in apoM. Hence, we show that apoM is positively related to leptin and negatively related to cholesterol in humans.

Adult↗

PubMed2004

Mass screening of 12,027 elderly men for prostate carcinoma by measuring serum prostate specific antigen.

BACKGROUND: The incidence of prostate carcinoma (Pca) has been increasing in China. We detected Pca in elderly men in Changchun, north China and the significance of prostate specific antigen (PSA) in mass screening and clinical staging of Pca. METHODS: Serum PSA from 12,027 men over 50 years old from Changchun was analyzed. In case of serum PSA greater than 4.0 ng/ml, the patient was suspected of potentially suffering from Pca, and transrectal six-point puncture prostate biopsies were performed under ultrasound guidance. Pathological examinations were performed on the biopsy tissue, and ABCD and TNM clinical stagings were used in accordance with international standards. Correlations between serum PSA level and clinical stage were analyzed. RESULTS: PSA was greater than 4.0 ng/ml in 813 patients (6.8% of the 12,027 men). Transrectal six-point prostate puncture biopsies guided by ultrasound were performed in 273 patients (33.6% of the 813 patients who were tested positive in the initial mass screening). Of these 273 patients, 69 cases of Pca (25.3% of 273) were confirmed by biopsy in the second screening, with an overall detection rate for Pca of 0.57% (69/12,027). The total number of patients in stages A, B, T1, or T2 was 57.9%, and over 20% of them suffered from late stage Pca with lymph node and bone metastasis. An obvious positive correlation was observed between ABCD staging, TNM staging, and serum PSA level. CONCLUSIONS: Serum PSA level is not only the golden standard for mass screening of Pca, but also the predictor for clinical stage of Pca. PSA testing revealed asymptomatic Pca cases in early, middle, and later stages in the elderly, suggesting that mass screening is of paramount importance.

Aged↗

PubMed2004

[Subconjunctival interleukin-1 receptor antagonist inhibits graft rejection following high-risk penetrating keratoplasty in rats].

OBJECTIVE: To observe the roles of subconjunctival administration of interleukin-1 receptor antagonist (IL-1ra) promoting corneal graft survival in rat models of high-risk penetrating keratoplasty. METHODS: Corneal vascularization was induced in 40 Sprague-Dawley rats (40 eyes) by passing 10-0 silk suture through the corneal stroma, and 30 of these rats received corneal grafts from Wistar rats to establish high-risk keratoplasty models and were divided into 3 groups to receive their respective treatment with IL-1ra eye drops (50 microg/ml), 1% CsA eye drops, administered 3 times a day, or no treatment. All the rats were treated by Tobra Dex eye drops and Tropicamid eye drops, 3 times a day for 14 consecutive days after the operation. During the 30-day observation, the survival of the grafts was recorded, and all the grafts were evaluated for signs of rejection. RESULTS: The mean survival times (MST) of the grafts of the treatment groups with IL-1ra and CsA were 12.00+/-1.50 d and 10.44+/-1.13 d respectively, significantly longer than that in the untreated model group (8.00+/-1.25 d, t=0.00, P<0.01), and the difference in the MST between the 2 treatment groups was also significant (t=0.00, P<0.01). CONCLUSION: Treatment with IL-1ra may significantly prolong high-risk corneal allograft survival.

Animals↗

PubMed2004

[Establish a screening system for selection of mRNA target sites for HBsAg to construct siRNA with shRNA].

OBJECTIVE: To find some effective short interfering RNA's sites targeting HBV surface gene sequence using shRNA expression vectors. METHODS: Four shRNA expression vectors targeting HBV surface gene sequence were constructed based on pAVU6 + 27 vector, and cotransfected into AD293 cells with HBs-EGFP fusion gene plasmid. The changes of HBs-EGFP image were detected by FACS and microscopy. The HBs-EGFP mRNA expression was evaluated by RT-PCR. RESULTS: Four shRNA expression vectors and HBs-EGFP fusion gene plasmid were successfully constructed. pAVU6 + 4sh579 vector inhibited the HBs-EGFP expression by 69.8% in AD293 and suppressed the HBs-EGFP mRNA expression by 74.6%. CONCLUSIONS: The results showed that the 579 site of HBV surface gene sequence was an effective target and pAVU6 + 4sh579 vector could suppress the HBs-EGFP expression in AD293 cells

Gene Expression Regulation, Viral↗

PubMed2004

[Transformation characteristics of sulfur forms in acid sulfate soils under different soil water conditions].

Aimed to detect the quantitative impact of soil water condition on the transformation of sulfur forms in acid sulfate soils (ASS), a simulation test was made with 8 treatments. The results indicated that water was an important factor affecting the transformation processes. Wet but not inundated or over dried condition was benefit to the oxidation of pyrite S and the formation of water soluble S (WS-S) and exchangeable S (Ex-S) in ASS. In the three treatments with different inundated and drained off cycles, soil pyrite S content averagely decreased 1.29-3.20 g x kg(-1) during a single drained off period, while soil WS-S and Ex-S contents averagely increased 0.90-1.63 and 0.58-1.47 g x kg(-1), respectively. During inundated period, soil pyrite S content was relatively stable, but soil WS-S and Ex-S contents were decreased significantly due to the dilution of water. It was suggested that the total S (mainly WS-S) of ASS was discharged in drainage process, and the accumulative amount of the discharge and the transformation of the S forms were associated with the length of the inundated and drained off cycles. The dynamics of Jarosite S, organic S and element S in all treatments were also discussed here.

Iron↗

PubMed2003

Airborne brake wear debris: size distributions, composition, and a comparison of dynamometer and vehicle tests.

Particle size distributions of light-duty vehicle brake wear debris are reported with careful attention paid to avoid sampling biases. Electrical low-pressure impactor and micro-orifice uniform deposit impactor measurements yield consistent size distributions, and the net particulate matter mass from each method is in good agreement with gravimetric filter measurements. The mass mean diameter of wear debris from braking events representative of urban driving is 6 microm, and the number-weighted mean is 1-2 microm for three currently used classes of lining materials: low metallic, semimetallic, and non-asbestos organic (NAO). In contrast, the wear rates are very material dependent, both in number and mass of particles, with 3-4 times higher emissions observed from the low metallic linings as compared to the semimetallic and NAO linings. Wind tunnel and test track measurements demonstrate the appearance of micron size particles that correlate with braking events, with approximately 50% of the wear debris being airborne for the test vehicle in this study. Elemental analysis of the wear debris reveals a consistent presence of the elements Fe, Cu, and Ba in both dynamometer and test track samples.

Air Pollutants↗

PubMed2003

Identification of human intestinal alkaline sphingomyelinase as a novel ecto-enzyme related to the nucleotide phosphodiesterase family.

Alkaline sphingomyelinase (alk-SMase) hydrolyzes dietary sphingomyelin and generates sphingolipid messengers in the gut. In the present study, we purified the enzyme, identified a part of the amino acid sequence, and found a cDNA in the GenBank coding for the protein. The cDNA contains 1841 bp, and the open reading frame encodes 458 amino acids. Transient expression of the cDNA linked to a Myc tag in COS-7 cells increased alk-SMase activity in the cell extract by 689-fold and in the medium by 27-fold. High activity was also identified in the anti-Myc immunoprecipitated proteins and the proteins cross-reacted with anti-human alk-SMase. Northern blotting of human intestinal tissues found high levels of alk-SMase mRNA in the intestine and liver. The amino acid sequence shared no similarity with acid and neutral SMases but was related to the ecto-nucleotide phosphodiesterase (NPP) family with 30-36% identity to human NPPs. Alk-SMase has a predicted signal peptide domain at the N terminus and a signal anchor domain at the C terminus. The ion-binding sites and the catalytic residue of NPPs were conserved, but the substrate specificity domain was modified. Alk-SMase had no detectable nucleotidase activity, but its activity against sphingomyelin could be inhibited by orthovanadate, imidazole, and ATP. In contrast to NPPs, alk-SMase activity was not stimulated by divalent metal ions but inhibited by Zn2+. Differing from NPP2, the alk-SMase cleaved phosphocholine but not choline from lysophosphatidylcholine. Phylogenetic tree indicated that the enzyme is a new branch derived from the NPP family. Two cDNA sequences of mouse and rat that shared 83% identity to human alk-SMase were identified in the GenBank. In conclusion, we identified the amino acid and cDNA sequences of human intestinal alk-SMase, and found that it is a novel ecto-enzyme related to the NPP family with specific features essential for its SMase activity.

Adenosine Triphosphate↗

PubMed2003

Water vapor diffusion effects on gas dynamics in a sonoluminescing bubble.

Calculations based on a consideration of gas diffusion of gas dynamics in a sonoluminescing bubble filled with a noble gas and water vapor are carried out. Xenon-, argon-, and helium-filled bubbles are studied. In the absence of shock waves, bubble temperatures are found to be decreased, a decrease attributable to the large heat capacity of water vapor. Peak bubble temperature reductions are seen in bubbles containing Xe or Ar but not in those containing He. Further extrapolations provide evidence for the occurrence of shock waves in bubbles with Xe and water vapor. No shock waves are observed in bubbles with Ar or He.

Journal Article↗

PubMed2003

E. coli pneumonia induces CD18-independent airway neutrophil migration in the absence of increased lung vascular permeability.

We examined the relationship between neutrophil [polymorphonuclear leukocyte (PMN)] influx and lung vascular injury in response to Escherichia coli pneumonia. We assessed lung tissue PMN uptake by measuring myeloperoxidase and transvascular PMN migration by determining PMN counts in lung interstitium and bronchoalveolar lavage fluid (BALF) in mice challenged intratracheally with E. coli. Lung vascular injury was quantified by determining microvessel filtration coefficient (Kf,c), a measure of vascular permeability. We addressed the role of CD18 integrin in the mechanism of PMN migration and lung vascular injury by inducing the expression of neutrophil inhibitory factor, a CD11/CD18 antagonist. In control animals, we observed a time-dependent sixfold increase in PMN uptake, a fivefold increase in airway PMN migration, and a 20-fold increase in interstitial PMN uptake at 6 h after challenge. Interestingly, Kf,c increased minimally during this period of PMN extravasation. CD11/CD18 blockade reduced lung tissue PMN uptake consistent with the role of CD18 in mediating PMN adhesion to the endothelium but failed to alter PMN migration in the tissue. Moreover, CD11/CD18 blockade did not affect Kf,c. Analysis of BALF leukocytes demonstrated diminished oxidative burst compared with leukocytes from bacteremic mice, suggesting a basis for lack of vascular injury. The massive CD11/CD18-independent airway PMN influx occurring in the absence of lung vascular injury is indicative of an efficient host-defense response elicited by E. coli pneumonia.

Animals↗

PubMed2003

Mass screening for prostate cancer: a comparative study in Natori, Japan and Changchun, China.

OBJECTIVES: To study the natural background of prostate cancer in Japan and China, mass checks with prostate-specific antigen (PSA)-based screenings were performed using identical procedures in Natori, Japan and Changchun, China. METHODS: For 7 years (1995 to 2001) in Natori, Japan, and for 3 years (1998 to 2000) in Changchun, China, 2212 Japanese and 3566 Chinese men older than 55 years were mass checked by PSA-based screening (serum PSA cutoff value 4.1 ng/mL). RESULTS: The PSA-positive rates (PSA 4.1 ng/mL or greater) and cancer detection rates in the screened persons of Natori and Changchun were 8.5% and 5.2% (P <0.0005) and 2.1% and 0.8% (P <0.0001), respectively. When the number of cancer cases detected was adjusted to a 100% biopsy rate for men who were PSA positive in both cities, the cancer detection rate was estimated at 2.3% and 1.3% in Natori and Changchun, respectively. This difference was also significant (P <0.01). CONCLUSIONS: The results indicate that the percentage of PSA-positive men 55 years or older in Changchun was lower than that in Natori. The analysis of the results suggests that the prostate cancer incidence and prevalence in Changchun, China are lower than those in Natori, Japan.

Age Factors↗

PubMed2003

Specific tissue expression and cellular localization of human apolipoprotein M as determined by in situ hybridization.

Apolipoprotein M (apoM) is a recently discovered human apolipoprotein predominantly present in high-density lipoprotein (HDL), and in minor proportion in triglyceride-rich lipoprotein (TGRLP) and low-density lipoprotein (LDL). The gene coding for apoM has been detected in all mammal genomes. The function of apoM is unknown yet. In the present study, we demonstrated that apoM is exclusively expressed in a strong manner in adult liver and kidney, and is expressed weakly in fetal liver and kidney as detected with human multiple tissue expression array. Both immunohistochemical staining and apoM mRNA in situ hybridization demonstrated that apoM was exclusively expressed in hepatocytes in human liver and in tubular epithelial cells in human kidney. The present study helps to elucidate the pathophysiological functions of apoM in vivo.

Apolipoproteins↗

PubMed2003

A constant-volume rapid exhaust dilution system for motor vehicle particulate matter number and mass measurements.

An improved version of the constant volume sampling (CVS) methodology that overcomes a number of obstacles that exist with the current CVS dilution tunnel system used in most diesel and gasoline vehicle emissions test facilities is presented. The key feature of the new sampling system is the introduction of dilution air immediately at the vehicle tailpipe. In the present implementation, this is done concentrically through a cylindrical air filter. Elimination of the transfer hose conventionally used to connect the tailpipe to the dilution tunnel significantly reduces the hydrocarbon and particulate matter (PM) storage release artifacts that can lead to wildly incorrect particle number counts and to erroneous filter-collected PM mass. It provides accurate representations of particle size distributions for diesel vehicles by avoiding the particle coagulation that occurs in the transfer hose. Furthermore, it removes the variable delay time that otherwise exists between the time that emissions exit the tailpipe and when they are detected in the dilution tunnel. The performance of the improved CVS system is examined with respect to diesel, gasoline, and compressed natural gas vehicles.

Air Pollutants↗

PubMed2003

[Glycocorticosteroid administration prevents fulminant hepatic failure occurrence in patients with chronic hepatitis B of severe degree].

OBJECTIVE: To prevent chronic severe hepatitis, even more fulminant hepatic failure (FHF) occurrence in patients with chronic hepatitis B of severe degree using steroid. METHODS: 120 patients were randomized into conventional supporting treatment and steroid treatment groups. The latter, 62 patients were given intravenously hydrocortisone sodium succinate at the dose of 150 mg to approximately 200 mg everyday plus support care. RESULTS: The rate of deteriorating to chronic severe hepatitis in steroid treatment group was significantly lower than that of conventional group (22% vs 48%, x(2) =7.60, P<0.01). 53.6% (15/28) patients with chronic severe hepatitis in conventional group died, while only 28.6% (4/14) in steroid treatment group succumbed to terminal liver disease (x(2)=0.02, P>0.05). There was no difference between the two groups regarding to complications incidence: gastrointestinal bleeding and infections except for some controllable serious reverse events, such as candidiasis, diabetes, herpes zoster and pulmonary tuberculosis found in some patients in steroid-treated group. CONCLUSION: These results suggest that steroid administration with improved support care not only is likely to prevent chronic severe hepatitis occurrence in patients with chronic viral hepatitis of severe degree, but also shows some efficacy for FHF, which warrant further investigation.

Adult↗

PubMed2003

[Organism distribution and drug resistance in 7 cases of severe acute respiratory syndrome death patients with secondary bacteria infection].

OBJECTIVE: To study the organism distribution and drug resistance of seven cases of severe acute respiratory syndrome (SARS) death patients with secondary bacterial infection. METHODS: Thirty strains of bacteria from seven cases of SARS patients with secondary bacterial infection were classified and drug resistance was analyzed. RESULTS: Seven cases of SARS death patients were all infected secondly and 5 cases were polyinfection. Twenty-four (31.5 percent) of 76 examed samples were positive. There were 30 strains of bacteria isolated from seven cases of SARS death patients with secondary bacterial infection. There were 9 strains of Gram negative bacteria (GNB), 8 strains of Gram positive cocci (GPC), and 13 strains of Fungi. The sensitive rate of vancomycin to GPC was 100.0 percent. The sensitive rate of imipenem, piperacillin/tazobactan was 100.0 percent, 44.5 percent, respectively. The sensitive rate of fluconazole to fungi was 92.4 percent. CONCLUSION: SARS patients are consitive to be infected secondary bacteria. Secondary bacteria infection is one of important reason of death.

Adult↗

PubMed2002

Association of prothrombin and protein S with plasma triglyceride-rich lipoproteins in humans after test meals rich in milk fat or soybean oil.

INTRODUCTION: Prothrombin can associate with rat chylomicrons in vitro. This enhances a platelet factor Xa mediated prothrombin activation when the chylomicron-prothrombin complex is exposed to platelets. Vitamin K-dependent pro- and anti-coagulation proteins are associated with TG-rich lipoproteins obtained from human plasma. In the present study, we examined the effects of saturated and unsaturated fat meals on the association of prothrombin and protein S with TG-rich lipoproteins in vivo. MATERIALS AND METHODS: Human EDTA plasma was separated from normal subjects after overnight fasting and 2.5 h after ingestion of either a saturated fat meal (butter and cream) or an unsaturated fat meal (soybean oil) containing 54-80 g fat (60.2 E%). The prothrombin and protein S in delipidated lipoproteins were determined by SDS-PAGE combined with Western blotting. RESULTS: Both prothrombin and protein S associated with TG-rich lipoproteins in fasting and in postprandial samples. The levels of prothrombin and protein S in postprandial TG-rich lipoproteins, especially after ingestion of a saturated fat meal, were higher than those in fasting TG-rich lipoproteins. CONCLUSIONS: The levels of both prothrombin and protein S in TG-rich lipoproteins in plasma increased after a single fat meal. This association is more pronounced after saturated fat meals and one may hypothesize that it can be linked to atherogenic properties of TG-rich lipoproteins.

Adult↗