Search PubMed⌕ Search

Biomedical subjects

Yong Xu

Publications and source records attributed to Yong Xu.

At least 109 records · Page 6Linked to original sources
PubMed2003

[Effect of Sophoricoside on histomorphology of bone in ovariectomized rats].

OBJECTIVE: To evaluate the potential preventive effect of Sophoricoside on bone loss in ovariectomized rats. METHODS: Female SD rats (n=50, 6 months old) were either sham-operated (SHAM group, n=10) or ovariectomized (n=40). Three days after operation, ovariectomized rats were randomly assigned to groups as follows: 10 received Sophoricoside 4 mg.kg(-1).d(-1) (SL group), 10 received Sophoricoside 8 mg.kg(-1).d(-1) (SM group), 10 received Sophoricoside 16 mg.kg(-1).d(-1) (SH group) and 10 were untreated (OVX group). After Sophoricoside were given orally for one month, the histomorphometric parameters in the secondary spongiosa of proximal tibia and lumbar vertebrae were examined. RESULTS: Compared with OVX group, SM and SH two kinds of treatment caused 15.28% and 22.81% increment in percent trabecular area (BV/TV, %) in the secondary spongiosa of proximal tibia, 14.23% and 21.2% increment in lumbar vertebrae. Accordingly in these two groups, there was a significant decrease in trabecular separation (FLAW, microm), but increment in trabecular width (Tb. Th, microm) and conjunction points (JOINT). But in SL group, the preventive effect was not observed. CONCLUSION: Sophoricoside can be efficient in preventing ovariectomy-induced bone loss in rats.

Animals↗
PubMed2003

[Medical value of isoflavones].

Isoflavones as a kind of phytoestrogen exist in soy plant widely. With the advantages of estrogen, they can regulate endocrine function of the human body, reduce blood cholesterol, decrease the incidence of coronary heart disease, prevent osteoporosis, inhibit tumor growth, and relieve pain. This article summarized the investigations on the medical value of isoflavones in recent years.

Animals↗
PubMed2003

Androgen and prostatic stroma.

AIM: To investigate the effect of androgen on the proliferation, differentiation and regression of canine prostatic stromal cells in vivo and human stromal cells in vitro. METHODS: Twenty-two dogs, including 15 normal prostate dogs and 7 prostatic hyperplasia dogs, had their serum concentration of testosterone and estrodiol determined by radioimmunoassay before and after castration. The expression of androgen receptor (AR) and estrogen receptor (ER) in the prostate were analysed by immunohistochemistry and semi-quantitative RT-PCR before and after castration. Light microscopy, transmission electron microscopy and TUNEL assay were carried out successively before and after castration to evaluate the prostatic histomorphology. In vitro serum-free cell cultures from human prostatic stroma were established and exposed to dihydrotestosterone (DHT). The proliferation of the cell culture was detected by MTT assay. The expression of TGFbgr, bFGF, AR, and smooth muscle cell (SMC) specific proteins (myosin and/or smoothelin) were detected using immunohistochemistry and RT-PCR. The differentiation from fibroblasts to smooth muscle cells was deduced by measuring the expression of SMC specific proteins. RESULTS: Before castration, the serum concentrations of testosterone and estrodiol were not statistically different between normal and hyperplasia groups. Following castration, the serum concentration of testosterone decreased rapidly in 2 days, and the concentration of estrodiol had no significant change compared with the pre-castration data. In the prostate, AR was presented in both the epithelial and stromal cells and the AR mRNA level was higher in hyperplasia than in normal prostate tissues (P<0.05). While ER predominantly existed in the prostate stromal cells and the ER mRNA had no difference between the hyperplasia and the normal group. Within the early phase of castration (<d7), the expression of AR was increased rapidly. Then it gradually dropped to a lower level than that of the pre-castration by the end of d90. The expression of ER remained unchanged in the whole course. The prostatic stromal cells, including SMCs and fibroblasts, diminished and underwent serial pathological changes of atrophy and apoptosis after castration. The atrophic cells were filled with huge intracellular lipofuscin. The expression of SMC myosin declined after castration, coincident with the increase in TGFbgr mRNA level and decline in bFGF mRNA level. In vitro, DHT caused a weak increase in the proliferation and expression of SMC-specific proteins (P<0.05). However, DHT and bFGF together stimulated the proliferation of stromal cells significantly more than either agent alone (P<0.01). The combination of DHT and TGFbgr greatly enhanced the expression of SMC-specific proteins (P<0.01) more strongly than either alone (P<0.01). CONCLUSION: The whole prostate gland is an androgen-sensitive organ with both the epithelium and stroma under the control of androgen. Androgen may direct the proliferation, differentiation and regression of stromal cells by regulating the expression of TGFbgr, bFGF, AR and smooth muscle cell specific proteins.

Animals↗
PubMed2003

[Water use efficiency and rice yield under different water managements].

Subtle plot experiment was conducted to study the growth and water use status of rice cultivated on waterlogged soil and upland soil mulched with plastic film, semi-decomposed wheat straw and nothing in Nanjing Agricultural University. The results showed that 349 to 473 mm of water were required by rice cultivated on upland soil mulched with film, straw or nothing, and 732.5 mm of water was required on waterlogged soil. The water productive efficiencies for rice grain and biomass were between 0.899 to 1.273, and 1.655 to 2.321 g.kg-1, respectively in upland cultivation, while 0.766 and 1.459 g.kg-1 in waterlogged cultivation. Rice cultivated on upland soil mulched with semi-decomposed straw achieved 90% or more economic yield on waterlogged soil.

Crops, Agricultural↗
PubMed2003

Effect of high glucose, angiotensin II and receptor antagonist Losartan on the expression of connective tissue growth factor in cultured mesangial cells.

OBJECTIVE: To observe the effect of high glucose, angiotensin II (AngII) and Losartan on the expression of connective tissue growth factor (CTGF) mRNA in cultured mesangial cells (MCs). METHODS: MCs of SD rats were isolated and cultured. High glucose (30 mmol/L) and AngII (10(-9), 10(-7), and 10(-5) mol/L) were added to the medium for 72 hours to observe the influence on CTGF mRNA expression. Losartan of 10(-5) mol/L and AngII of 10(-5) mol/L were added to the medium to observe the effects of Losartan on CTGF mRNA expression stimulated by AngII. The expressions of CTGF mRNA were detected by reverse transcriptase polymerase chain reaction (RT-PCR). RESULTS: RT-PCR showed that high glucose and AngII up-regulated the expression of CTGF mRNA, and AngII stimulated the expression in a dose-dependent manner. Expression of CTGF mRNA induced by AngIIwas partially suppressed by 10(-5) mol/L Losartan (P < 0.05). CONCLUSIONS: High glucose and AngII can enhance the expression of CTGF mRNA and thus be involved in the process of renal fibrosis. Losartan can have a partial fibrogenesis-inhibiting effect, with implications for the treatment of renal fibrosis.

Angiotensin II↗
PubMed2003

[T(H1) and T(H2) cells in children with mycoplasma pneumonia].

OBJECTIVE: To Study T lymphocyte subsets, including T(H1) and T(H2) cells in peripheral blood mononuclear cells (PBMC) of children with mycoplasma pneumonia, understand immunopathogenesis and explore the possibility of immunotherapy of patients with mycoplasma pneumonia. METHODS: Fresh peripheral blood samples of patients from two groups, group 1, mycoplasma pneumonia (MP) group (35 cases, 15 males and 20 females, age range 3 - 13 years, mean 9 years), and control group consisted of 28 healthy children (14 males and 14 females, age range 3 - 12 years, mean 7 years) were treated and run through the flow cytometry. The data were obtained by using Simultest IMK-Lymphocyte software and the percentage of CD(3)(+), CD(3)(+)CD(4)(+), CD(3)(+)CD(8)(+), CD(3)(-)CD(19)(+) and CD(3)(-)CD(16 + 56)(+) cells were counted. The percentage of T(H1) and T(H2) cells were gained through determination of intracellular cytokines IFN-gamma or IL-4 in CD(4)(+) cells by flow cytometry. The 35 patients with MP were hospitalized at our hospital. In addition to fever and cough, all the patents had abnormal X-ray findings and/or moist rale on auscultation of the lungs. The IgM antibody to Mycoplasma pneumoniae was positive in each patient. Immunoglobulins were measured, and PPD skin tests were performed in 30 out of the 35 patients with MP. T test and rank sum test by SPSS FOR WINDOWS 10.0 was used for statistical analysis. RESULTS: The percentage of CD(3)(+) and CD(4)(+) T lymphocyte was 68.00 +/- 6.66 and 37.86 +/- 5.84, respectively, in MP group, and 63.71 +/- 7.92 and 34.54 +/- 6.23 in control group (P < 0.05). The percentage of T(H1) cells was 14.13 +/- 8.46 in patients and 20.77 +/- 6.89 in normal control group (P = 0.001). The percentage of NK cells was 15.57 +/- 12.16 and 20.39 +/- 9.64 in MP and control group (P < 0.01). The ratio of T(H1)/T(H2) in MP group was lower than that in control group (P < 0.05). However the percentage of CD(8), T(H2), B cells and CD(4)/CD(8) had no difference between the MP and control groups. The levels of IgG, IgA, and IgM in serum were normal in most of patients except for a few patients who had elevated IgA and IgM levels. The PPD skin tests were negative in 30 out of 35 patients. CONCLUSION: In this study a higher percentage of CD(3)(+), CD(4)(+) T lymphocyte and lower percentage of T(H1), NK cells in PBMC of patients with mycoplasma pneumonia were found. The ratio of T(H1) and T(H2) cells in patients was also lower. None of thirty patients had positive PPD skin tests. Unbalanced cell-mediated immunity with a tendency toward T(H2) existed in patients with MP. Therefore, immunomodulators may be useful in treatment of mycoplasma pneumonia.

Adolescent↗
PubMed2003

[Effects of TNF-alpha receptor blocking peptide on adjuvant arthritis in rats].

AIM: To study the effects of TNF receptor blocking peptide on adjuvant arthritis in rats. METHODS: The model of rat adjuvant arthritis was induced by injection of complete Freund's adjuvant. The TNF receptor blocking peptide was injected locally in the ankle. The ankle swelling, the pathologic changes in the ankle joint and the expression of IL-1 beta mRNA and TNF-alpha mRNA by peritoneal macrophages (RT-PCR) were observed. RESULTS: The model of rat adjuvant arthritis induced by injection of complete Freund's adjuvant was similar to human rheumatoid arthritis. The treatment with TNF receptor blocking peptide for 10 days resulted in complete inhibition of joint swelling, a decrease in infiltration of inflammatory cell into joint tissue, an obvious alleviation of inflammatory pathological damages and an apparent decline of TNF-alpha mRNA and IL-1 beta mRNA of peritoneal macrophages of rats. CONCLUSION: The TNF receptor blocking peptide can protect the joint from inflammatory damage induced by adjuvant arthritis by suppression of TNF-alpha and IL-1 production, thereby alleviating the pathological injury of joint and controlling effectively the clinic course of arthritis.

Animals↗
PubMed2003

[Effect of the two types of TNF-alpha on the biological functions of monocytic cell line U937].

AIM: To compare the effect of the two types of TNF-alpha, transmembrane TNF-alpha (TM-TNF-alpha) and secreted TNF-alpha (sTNF-alpha) on the biological functions of monocytic cell line U937 so as to explore the role of TM-TNF-alpha in inflammation. METHODS: Effect of the two types of TNF-alpha on the functions of U937 cells, such as phagocytosis, accumulation of cytokines' mRNA, the level of cytoplasmic IkappaB-alpha and expression of ICAM-1, was compared by phagocytosis, RT-PCR, Western blot and FACS. RESULTS: sTNF-alpha was found to be able to promote markedly phagocytosis by monocytic U937 cells, enhance the mRNA accumulation of cytokines, such as TNF-alpha, IL-1beta and IL-8 mRNA, induce the degradation of IkappaB-alpha and the expression of adhesion molecule ICAM-1; while TM-TNF-alpha was shown to have no effect on the functions above of U937 cells. Furthermore, it seemed TM-TNF-alpha did not have a synergic action with sTNF-alpha when U937 cells was treated with both types of TNF-alpha. CONCLUSION: The data above shows that sTNF-alpha can activate U937 cells, while TM-TNF-alpha has no influence. It suggests that the two types of TNF-alpha may play the different role in inflammation.

Humans↗
PubMed2002

Identification of an intracellular receptor for lysophosphatidic acid (LPA): LPA is a transcellular PPARgamma agonist.

Lysophosphatidic acid (LPA) is a pluripotent lipid mediator acting through plasma membrane-associated LPA(x) receptors that transduce many, but not all, of its effects. We identify peroxisome proliferator-activated receptor gamma (PPARgamma) as an intracellular receptor for LPA. The transcription factor PPARgamma is activated by several lipid ligands, but agonists derived from physiologic signaling pathways are unknown. We show that LPA, but not its precursor phosphatidic acid, displaces the drug rosiglitazone from the ligand-binding pocket of PPARgamma. LPA and novel LPA analogs we made stimulated expression of a PPAR-responsive element reporter and the endogenous PPARgamma-controlled gene CD36, and induced monocyte lipid accumulation from oxidized low-density lipoprotein via the CD36 scavenger receptor. The synthetic LPA analogs were effective PPARgamma agonists, but were poor ones for LPA(1), LPA(2), or LPA(3) receptor transfected cells. Transfection studies in yeast, which lack nuclear hormone and LPA(x) receptors, show that LPA directly activates PPARgamma. A major growth factor of serum is LPA generated by thrombin-activated platelets, and media from activated platelets stimulated PPARgamma function in transfected RAW264.7 macrophages. This function was suppressed by ectopic LPA-acyltransferase expression. LPA is a physiologic PPARgamma ligand, placing PPARgamma in a signaling pathway, and PPARgamma is the first intracellular receptor identified for LPA. Moreover, LPA produced by stimulated plasma platelets activates PPARgamma in nucleated cells.

Animals↗
PubMed2002

Synthesis of chiral (alpha,alpha-difluoroalkyl)phosphonate analogues of (lyso)phosphatidic acid via hydrolytic kinetic resolution.

The hydrolytic kinetic resolution of 1,1-difluoro-3,4-epoxy-butylphosphonate using a chiral salen-Co complex was employed as a key step to obtain enantiomeric diols in 99% ee as key intermediates. The enantiomerically homogeneous (alpha,alpha-difluoroalkyl)phosphonates were obtained after selective esterification and deprotection of the corresponding phosphonates. These compounds are novel phosphatase-resistant analogues of lysophosphatidic acid and phosphatidic acid. [reaction: see text]

Hydrolysis↗
PubMed2002

Concise synthesis of acyl migration-blocked 1,1-difluorinated analogues of lysophosphatidic acid.

Lysophosphatidic acid (LPA, 1- or 2-acyl-sn-glycerol 3-phosphate) is an important phospholipid mediator produced by activated platelets and by ovarian cancer cells. Efforts to understand LPA signaling through G-protein-coupled receptors are hampered by the facile acyl migration that results in equilibration to a mixture of the 1- or 2-acyl species under physiological conditions. We describe a new and efficient route to enantiomerically homogeneous lysophospholipid analogues from D-mannitol 1,2:5,6-bis-acetonide to give two 1,1-difluorodeoxy analogues of (2R)-acyl-sn-glycerol 3-phosphate. These compounds are migration-blocked analogues of the labile sn-2 LPA species. The (19)F NMR of diastereotopic fluorines of the difluoromethyl group shows an unexpected solvent dependence.

Combinatorial Chemistry Techniques↗
PubMed2002

Absorption and scattering images of heterogeneous scattering media can be simultaneously reconstructed by use of dc data.

We present a carefully designed phantom experimental study aimed to provide solid evidence that both absorption and scattering images of heterogeneous scattering media can be reconstructed independently from dc data. We also study the important absorption-scattering cross-talk issue. In this regard, we develop a simple normalizing scheme that is incorporated into our nonlinear finite-element-based reconstruction algorithm. Our results from the controlled phantom experiments show that the cross talk of an absorption object appearing in scattering images can be eliminated and that the cross talk of a scattering object appearing in absorption images can be reduced considerably. In addition, these carefully designed phantom experiments clearly suggest that both absorption and scattering images can be simultaneously recovered and quantitatively separated in highly scattering media by use of dc measurements. Finally, we discuss our results in light of recent theoretical findings on nonuniqueness for dc image reconstruction.

Absorption↗
PubMed2002

Human prostate cancer cell death by novel anticancer compounds, apoptosis-inducing nucleosides from CD57+ HLA-DR(bright) natural suppressor cell line.

BACKGROUND: We validated the induction of apoptosis in human prostate cancer PC3 cells by apoptosis-inducing nucleosides (AINs) released from the CD57(+)HLA-DR(bright)-natural suppressor (57.DR-NS) cell line. We analyzed the molecular signaling pathway during AINs-induced apoptosis in PC3 cells. METHODS: Direct and indirect co-cultures between 57.DR-NS and PC3 cells were performed. AINs were isolated by high-performance liquid chromatography (HPLC) from 57.DR-NS cell cultures. Apoptosis in PC3 cells was analyzed by DNA fragmentation, sub-G(1) DNA content with flow cytometry, and terminal deoxynucleotide transferase-mediated dUTP nick end-labeling (TUNEL) method. The DNA strand breaks and activation of caspase-3 in PC3 cells were measured by DNA unwinding and flow cytometry assay. RESULTS: The 57.DR-NS cell line generated apoptosis in PC3 cells via AINs. AINs isolated from 57.DR-NS cell cultures induced apoptosis in PC3 cells. Furthermore, we found DNA strand breaks followed by activation of caspase-3 during AINs-induced apoptosis in PC3 cells. CONCLUSIONS: The data obtained here indicated that AINs could induce apoptosis in PC3 cells through DNA strand breaks and activation of caspase-3.

Apoptosis↗
PubMed2002

Transcriptional regulation of the human manganese superoxide dismutase gene: the role of specificity protein 1 (Sp1) and activating protein-2 (AP-2).

Manganese superoxide dismutase (MnSOD) plays an important role in regulating cellular redox conditions. Expression of MnSOD has been shown to protect against damage by oxidative stress and to suppress the malignant phenotype of human cancer cells. We have previously cloned the human MnSOD (SOD2) gene and analysed its 5' proximal promoter, which has been characterized by a lack of a TATA or CAAT box and the presence of multiple GC boxes. To define further the molecular mechanisms for the regulation of MnSOD expression, multiple transcription factor-binding motifs containing overlapping specificity protein 1 (Sp1)- and activator protein (AP)-2-binding sites were identified by DNase I footprinting analysis. Functional studies in three cell lines with different levels of Sp1 and AP-2 proteins suggested that the cellular levels of these proteins may differentially regulate transcription via GC-binding motifs in the human SOD2 promoter. Co-transfection of an Sp1 expression vector resulted in an increase in the transcription of the promoter-driven reporter gene. In contrast, co-transfection of the AP-2 expression vector caused a decrease in transcription. Direct mutagenesis analysis of Sp1- and AP-2-binding sites showed that Sp1 is essential for transcription of the human SOD2 gene, whereas AP-2 plays a negative role in the transcription. Immunoprecipitation of Sp1 and AP-2 proteins demonstrated that Sp1 interacts with AP-2 in vivo. Two-hybrid analysis revealed that interaction between Sp1 and AP-2 plays both a positive and negative role in the transcription of the reporter gene in vivo. Taken together, our data indicate that AP-2 down-regulates transcription of the human SOD2 gene via its interaction with Sp1 within the promoter region. These findings, coupled with our previous observation that several cancer cell lines have mutations in the promoter region of the human MnSOD gene, which lead to an increase in an AP-2-binding site and a decrease in the promoter activity, signal the importance of understanding the promoter structure and the regulation of the human SOD2 gene by Sp1 and AP-2.

Base Sequence↗
PubMed2002

Analysis on the causes for refractory GERD.

To analyze the causes of failure in conventional treatment to refractory gastroesophageal reflux diseases (GERD) patients, 16 refractory GERD patients (group R) and 16 cases of GERD primarily diagnosed (group P) were studied. Endoscopy, pathologic examination and 14C urea breath test were conducted in every patient. 24 h ambulatory pH and bilirubin monitoring were performed with Digitrapper MK III and Synetics Bilitec 2000. It was found that esophagitis in group R was more severe than in group P. The rate of Helicobacter pylori infection in group R was significantly lower than in group P. Fraction time pH below 4.00 was not longer while the bile reflux represented by fraction time abs above 0.14 was greater for patients in the group R as compared with those in the group P. The mixed refluxes and pure bile refluxes between the two groups had significant difference. The reflux episodes in the group R mainly occurred during nights. These results indicated that severe esophagitis, especially Barrett's esophagus with complications makes it difficult to control GERD. Severe duodenogastroesophageal refluxes (DGER) are often accompanied by refractory GERD. Mixed refluxes aggravate the esophageal injuries. Pure bile refluxes and nocturnal refluxes may cause failure of administration of proton pump inhibitors (PPI) in the morning. Helicobacter pylori infection and acid refluxes may not be the direct cause of refractoriness. Individual refractory GERD patient without abnormal results on pH or bile reflux recently should be diagnosed again.

Adult↗
PubMed2002

Transcription regulation of human manganese superoxide dismutase gene.

The human MnSOD gene has a typical housekeeping gene promoter, but is highly inducible by various physical, chemical, and biological agents. Transcription factors SP-1 and AP-2 seem to have opposite roles in the transcriptional activity of the basal promoter. Whereas SP-1 plays a positive role, which is absolutely essential for transcription from the human MnSOD promoter, AP-2 appears to play a negative role in this process. An enhancer element is found in the promoter region of the human MnSOD gene. Several important enhancer elements are located in the second intron. The NF-kappa B site in the second intron is essential but not sufficient for high-level induction of MnSOD by cytokines. Although mutations in the regulatory elements may be partially responsible for the lack of induction of MnSOD in some cell types, differences in the degree of induction exist that cannot be accounted for by the defect in the DNA sequence. It is highly likely that this difference is due to the presence or absence of coactivator or suppressor proteins in the cells and may have a physiological role in the defense against oxidative stress.

Base Sequence↗
PubMed2002

Near-infrared optical imaging of the breast with model-based reconstruction.

RATIONALE AND OBJECTIVES: Near-infrared diffuse optical imaging may offer enhanced contrast resolution over that of the existing technologies for detection and diagnosis of breast cancer. The authors report quantitative absorption and scattering images of the human breast with model-based reconstruction methods using near-infrared continuous-wave tomographic data. MATERIALS AND METHODS: An automatic, multichannel optical imaging system was used to image the breasts of nine women: four with infiltrating ductal carcinomas, one with infiltrating lobular carcinoma, one with fibroadenoma, and three control subjects with no breast lesion. The image reconstruction methods are centered on the finite element solution of photon diffusion in breast tissue. RESULTS: Substantial contrast between tumor and adjacent parenchyma was observed. Images of the control subjects showed homogeneous optical features. In the six women with breast lesions, the locations and sizes of tumors imaged optically were accurate and consistent with the mammographic findings. CONCLUSION: The results of this pilot study show that cancers as small as 5 mm can be quantitatively imaged. In addition, preliminary data from the scattering images suggest that benign and malignant tumors can be noninvasively differentiated with optical imaging.

Adenocarcinoma↗