Biomedical subjects

X Peng

Publications and source records attributed to X Peng.

At least 37 records · Page 2Linked to original sources

PubMed2001

Uterine receptivity in the baboon: modulation by chorionic gonadotropin.

Embryonic signals not only rescue the corpus luteum but also modulate the uterine environment in preparation for implantation. Chorionic gonadotropin (CG), an early embryonic signal, is one such molecule. In vivo studies in the baboon show that CG alters the morphology and biochemical activity of the uterus, especially with respect to the three major cell types: luminal epithelium, glandular epithelium, and stromal fibroblasts. Further, CG and progesterone have a synergistic effect on the receptive endometrium. CG action on the endometrial cells is transduced via a seven transmembrane G protein-coupled receptor. Possible signaling pathways involved are discussed.

Animals↗

PubMed2001

Effects of co-stimulation by CD58 on human T cell cytokine production: a selective cytokine pattern with induction of high IL-10 production.

CD58 is the ligand for the CD2 molecule on human T cells and has been shown to provide a co-stimulatory signal for T cell activation. However, its physiological role is still unclear. We studied the effects of co-stimulation by CD58 on the production of T(h)1-type (IL-2- and IFN-gamma) or T(h)2 type (IL-4, IL-5 and IL-10) cytokines in an in vitro culture system of purified human T cells with CD58-transfected P815 cells and with anti-CD3 as the primary stimulus. Co-stimulation of T cells by CD58 potently induced IL-10 and IFN-gamma production (at the protein and at the mRNA level), and transforming growth factor-ss production (at the mRNA level), comparable to what can be found in CD80 co-stimulated T cell cultures. In contrast, we found low to absent IL-2, IL-4, IL-5, IL-13 and tumor necrosis factor-alpha production after CD58 co-stimulation, and this was not due to suppressive effects of endogenously produced IL-10. CD80 co-stimulation strongly induced all these cytokines. Intracellular staining for cytokine expression revealed the existence of a T cell subpopulation induced by CD58 co-stimulation to produce both IFN-gamma and IL-10. We furthermore found that the selective cytokine profile induced by CD58 co-stimulation is further accentuated by rIL-12 and by rIFN-alpha. Using cyclosporin A as an inhibitor of the calcineurin enzyme, we could show that production of all cytokines in this system is calcium dependent. CD58 co-stimulation thus induces a cytokine pattern corresponding to that described for T regulatory (T(r)) 1 cells and to the pattern reported to be induced by the newly identified B7 family member, B7-H1.

Adult↗

PubMed2001

Decrease in cell surface galactose residues of Schizosaccharomyces pombe enhances its coflocculation with Pediococcus damnosus.

Pediococcus damnosus can coflocculate with Saccharomyces cerevisiae and cause beer acidification that may or may not be desired. Similar coflocculations occur with other yeasts except for Schizosaccharomyces pombe which has galactose-rich cell walls. We compared coflocculation rates of S. pombe wild-type species TP4-1D, having a mannose-to-galactose ratio (Man:Gal) of 5 to 6 in the cell wall, with its glycosylation mutants gms1-1 (Man:Gal = 5:1) and gms1Delta (Man:Gal = 1:0). These mutants coflocculated at a much higher level (30 to 45%) than that of the wild type (5%). Coflocculation of the mutants was inhibited by exogenous mannose but not by galactose. The S. cerevisiae mnn2 mutant, with a mannan content similar to that of gms1Delta, also showed high coflocculation (35%) and was sensitive to mannose inhibition. Coflocculation of P. damnosus and gms1Delta (or mnn2) also could be inhibited by gms1Delta mannan (with unbranched alpha-1,6-linked mannose residues), concanavalin A (mannose and glucose specific), or NPA lectin (specific for alpha-1,6-linked mannosyl units). Protease treatment of the bacterial cells completely abolished coflocculation. From these results we conclude that mannose residues on the cell surface of S. pombe serve as receptors for a P. damnosus lectin but that these receptors are shielded by galactose residues in wild-type strains. Such interactions are important in the production of Belgian acid types of beers in which mixed cultures are used to improve flavor.

Cell Wall↗

PubMed2001

Distribution of nitric oxide synthase in stomach myenteric plexus of rats.

AIM: To study the distribution of nitric oxide synthase (NOS) in rat stomach myenteric plexus. METHODS: The distribution of NOS in gastric wall was studied in quantity and location by the NADPH-diaphorase (NDP) histochemical staining method and whole mount preparation technique. RESULTS: NOS was distributed in whole stomach wall, most of them were located in myenteric plexus, and distributed in submucosal plexus.The shape of NOS positive neurons was basically similar, most of them being round and oval in shape. But their density, size and staining intensity varied greatly in the different parts of stomach. The density was 62+/-38 cells mm(2) (antrum), 43+/-32 cells/mm(2) (body), and 32+/-28 cells mm(2) (fundus), respectively. The size and staining intensity of NOS positive neurons in the fundus were basically the same, the neurons being large and dark stained, while they were obviously different in antrum. In the body of the stomach, the NOS positive neurons were in an intermediate state from fundus to antrum. There were some beadlike structures which were strung together by NOS positive varicosities in nerve fibers, some were closely adherent to the outer walls of blood vessels. CONCLUSION: Nitric oxide might be involved in the modulation of motility, secretion and blood circulation of the stomach, and the significant difference of NOS positive neurons in different parts of stomach myenteric plexus may be related to the physiologic function of stomach.

Animals↗

PubMed2001

Involvement of pressure-related mechanism in activation of inducible nitric oxide synthase.

The goal of this study was to clarify the relationship between blood pressure and inducible nitric oxide synthase (iNOS) activity. Different levels of blood pressure were obtained by long-term (six days) intravenous infusion of different concentrations (0.3%-8%) of NaCl solution to normal SD rats. iNOS activity assay and measurement of urinary nitrate/nitrite (UNOx), an index of NO production of the whole body, were carried out by isotope-labeled L-arginine conversion rate measurement and Greiss Reaction respectively. Groups of normotensive and hypertensive rats including normal Wistar rats, normal Sprague-Dawley (SD) rats, high NaCl-induced hypertensive rats (NaHR) and spontaneously hypertensive rats (SHR) were used to detect the changes in iNOS protein under normotension and hypertension by Western blotting. iNOS activity of aorta and kidney tissues and UNOx increased more significantly in hypertensive animals than in the normotensive control ones. Accordingly, iNOS protein in the aortas of NaHR and SHR increased by 149% and 261% respectively. It is suggested that in addition to cytokine and bacterial products etc, blood pressure is also an effective regulatory factor involved in iNOS activation and expression.

Animals↗

PubMed2001

[Serum markers and pathological evaluation in hepatitis fibrosis of chronic hepatitis B treated with interferon alpha].

OBJECTIVE: To evaluate the anti-fibrotic effect of interferon alpha and to study the relationship between the anti-fibrotic effect and the efficacy of anti-virus in patients with chronic hepatitis B treated with interferon alpha. METHODS: Thirty-six patients with chronic hepatitis B were treated with interferon alpha. Before, during and after the treatment, the levels of hyaluronic acid (HA), type III procollagen (PC-III), type IV collagen(IV-C), laminin (LN) and transforming growth factor beta 1 (TGF-beta 1) were measured as the markers of hepatic fibrosis. Needle biopsy sections of the liver taken before and at the end of IFN treatment were assessed and compared according to the modified histological activity index (HAI) and hepatic fibrosis (HF) scoring system. RESULTS: In IFN group, the levels of HA, PC-III, IV-C, LN, and TGF-beta 1 after treatment were all significantly lower than those before treatment (P<0.01). The levels of HA, PC-III, and TGF-beta 1 after treatment were significantly lower in IFN group than in control one. HAI scores decreased from 9.3+/-3.2 to 6.2 +/-2.1 and HF scores decreased from 7.5+/-2.2 to 5.1+/-1.8 after treatment. CONCLUSIONS: The improvement of hepatic fibrosis closely related to the efficacy of anti-virus. Interferon alpha therapy is effective for hepatic fibrosis of chronic hepatitis B.

Adolescent↗

PubMed2001

[The effectiveness of prolene patch in hernia prevention following harvesting rectus abdominis myocutaneous flap].

OBJECTIVE: To investigate the effectiveness of polypropylene path (Prolene) in hernia prevention following harvesting of rectus abdominis is myocutaneous flap. METHODS: From November 1999 to October 2000, Prolene patches were applied in 26 cases to repair the anterior rectus sheath following harvesting free rectus abdominis myocutaneous flap. Data concerning each case included size of rectus flap, defect of rectus sheath, size of patch used, wound healing and complications. RESULTS: Prolene patch showed good biocompatibility with abdominal tissue. No foreign-body rejection occurred after operation. Seroma developed in 1 case, and was drained bedside without complication. All prolene patches healed well in the body during follow-up. Hernia formation and abdominal bulge were not observed. CONCLUSION: Prolene patch is a satisfactory material for repair of the anterior rectus sheath after harvesting free rectus abdominis myocutaneous flap.

Adolescent↗

PubMed2001

[Treatment of acute aplastic anemia with allogeneic peripheral blood stem cell transplantation: a case report and literature review].

OBJECTIVE: To report a patients with acute aplastic anemia(AAA) successfully treated with allogeneic peripheral blood stem cell transplantation(allo-PBSCT). METHODS: A 30 years old patient with AA received allo-PBSCT from a HLA-compatible sibling donor. PBSCs mobilization regimen was G-GSF 250 micrograms/d x 6. The conditioning regimen included (CTX 50 mg.kg-1.d-1) x 4 and (ATG 10 kg-1.d-01) x 2. 8.97 x 10(8) nucleated cells/kg, 9.20 x 10(6) CD34+ cells/kg, 11.20 x 10(5) CFU-GM/kg were transplanted. RESULTS: Hematopoietic reconstitution obtained on day 18 after allo-PBSCT. Monitoring of engraftment with three microsatellite markers showed mixed chimerism on day 18 and complete chimerism after day 25. No acute or chronic graft versus host disease (GVHD) occurred. In the follow-up duration of 240 days, the blood and bone marrow pictures were normal and the living status was good. CONCLUSION: Allo-PBSCT was an effective therapy in the treatment of acute aplastic anemia.

Acute Disease↗

PubMed2001

[Accurate diagnosis of stages of hepatic fibrosis by measuring levels of serum hyaluronic acid, procollagen type III, and collagen type IV].

OBJECTIVE: To study the accurate diagnosis of various stages of hepatic fibrosis by measuring serum hyaluronic acid (HA), procollagen type III (PC III), and collagen type IV (CIV). METHODS: The concentrations of serum HA, PC III, CIV in 253 patients with chronic liver disease were measured by radioimmunoassay. Liver biopsies were performed in all of the patients at the same time. According to the results of liver pathological diagnosis, we assessed the ability of serum HA, PC III and CIV to identify correctly patients with hepatic fibrosis (staging >or=S(2)) or cirrhosis (S(4)). RESULTS: The cutoff value of HA, PC III and C IV to identify correctly patients with hepatic fibrosis was 90 microg/L, 90 microg/L, 75 microg/L respectively. The sensitivity (Se) was 80.4%, 82%, 63.1%; the specificity (Spe) was 70.2%, 60.8%, 83.8%; the positive prediction value (PPV) was 86.7%, 83.5%, 90.4%; the negative prediction value (NPV) was 59.8%, 58.4%, 48.4%, respectively. The cutoff value to identify patients with cirrhosis was: HA 210 microg/L, Se 96.2%, Spe 85.3%, PPV 65.4%, NPV 98.8%; PC III 150 microg/L, Se 76.4%, Spe 68.7%, PPV 40.4%, NPV 91.3%; C IV 90 microg/L, Se 80%, Spe 75.8%, PPV 47.8%, NPV 93.2%, respectively. CONCLUSIONS: The determination of serum HA, PC III and C IV can make relatively accurate diagnosis to various stages of hepatic fibrosis. HA is the best for diagnosis of liver cirrhosis.

Biopsy↗

PubMed2001

[Modulation of human small cell lung cancer cell line GLC4/ADR multidrug resistance in the inhibition of multidrug resistance-associated protein and its antisense].

OBJECTIVE: To study the effect of antisense multidrug resistance-associated protein (MRP) RNA on multidrug resistance (MDR) in the human small cell lung cancer (SCLC) cell line GLC4/ADR, in which the overexpression of MRP gene is discovered. METHODS: In using the plasmid pRC/RSV-MRP1 containing complete ORF of MRP as a template, two antisense recombinants targeting at the 5' and 3' regions were constructed with the application of the polymerase chain reaction (PCR) technique. Lipofectamine was conducted to transduce these antisense MRPs into the GLC4/ADR cells. Three clones (the GLC4/ADR-pcDNA3, MO; GLC4/ADR-MRP-5' region, Ma; GLC4/ADR-MRP-3' region, Mb) of transfectants after the selection of G418 were obtained. The expression of MRP protein was detected by the use of the Western blot and the MTT method for determination of chemosensitivity to ADR was used. RESULTS: The antisense MRPs was found to be effectively expressed in the clones, being transfected with two different antisense MRPs. The MRP expression in these transfectants were inhibited at the rates of 14.0% (GLC4/ADR Ma) and 83.0% (GLC4/ADR Mb), respectively. Moreover, decrease in the ADR resistance was observed in the Ma and Mb at the rates of 9.5% and 28.4%. Although the intracellular ADR concentration was increased in these transfectants, the proliferation and cell cycle and their early apoptosis induced by the ADR, indicated no difference between the transfectants and parental cells. CONCLUSION: It is possible to obtain the effective expression of the MRP antisense structures for the blocking of the mRNA translation in GLC4/ADR cell line and the fragment complementary to the 3'-region of MRP is more effective for the inhibition of the MRP than that related to the 5'-region of MRP. The antisense RNA may be a useful treatment in combination with the conventional chemotherapy for SCLC, in which the MRP overexpression usually occurs.

ATP Binding Cassette Transporter, Subfamily B↗

PubMed2001

[The relationship between postburn enterogenic hypermetabolism and decontamination of intestine].

OBJECTIVE: To explore whether postburn enterogenic hypermetabolism exists. METHODS: Eighty -- eight Wistar rats inflicted by 30% TBSA III degree burns were randomly divided into two groups, i,e. burn (B) and burn with gut decontamination (D) groups. The change in resting energy expenditure (REE) was observed during 0 to 10 postburn day (PBDs) in rats. The plasma contents of lipopolysaccharide (LPS), tumor necrosis factor (TNF) and interleukin-1 (IL-1) were determined on 1, 3, 5, 7 and 10 PBDs and their correlations were analyzed. RESULTS: The postburn REE and plasma contents of TNF, LPS and IL-1 were much higher in both groups than those before injury. When compared between the two groups, the above data in D group were lower in varying degrees than those in B group. It was shown by correlation analysis that REE was postively correlated to LPS, TNF and IL-1, respectively (gamma = 0.77 similar 0.9, P < 0.05 similar 0.01). CONCLUSION: Postburn hypermetabolism in rats could be ameliorated by gut decontamination, and the postburn plasma inflammatory mediators in rats could also be lowered by gut decontmination. This suggests that enterogenic hypermetabolism does exist after burn injury.

Animals↗

PubMed2001

Kinetics of inactivation of Ulva pertusa Kjellm alkaline phosphatase by ethylenediaminetetraacetic acid disodium.

Ulva pertusa Kjellm alkaline phosphatase (EC 3.3.3.1) is a metalloenzyme, the active site of which contains a tight cluster of two zinc ions and one magnesium ion. The kinetic theory described by Tsou of the substrate reaction during irreversible inhibition of enzyme activity has been employed to study the kinetics of the course of inactivation of the enzyme by EDTA. The kinetics of the substrate reaction at different concentrations of the substrate p-nitrophenyl phosphate (PNPP) and inactivator EDTA indicated a complexing mechanism for inactivation by, and substrate competition with, EDTA at the active site. The inactivation kinetics are single phasic, showing that the initial formation of an enzyme-EDTA complex is a relative rapid reaction, following by a slow inactivation step that probably involves a conformational change of the enzyme. The presence of Zn2+ apparently stabilizes an active-site conformation required for enzyme activity.

Alkaline Phosphatase↗

PubMed2001

[Detection of TTV DNA from high background nuclear acid samples using specific nuclear acid captured-polymerase chain reaction].

OBJECTIVE: To improve the amplification of non-specificity of TTV DNA detection using PCR from high background nuclear acids because of its low level in samples. METHODS: Specific nuclear acid captured PCR(SNAC-PCR) was established through capturing TTV DNA onto microplate with specific nuclear acid by means of avidin-biotin system, then amplifying captured TTV DNA as usual. Its specificity was evaluated by comparing with the detection of routine extraction samples using nested-PCR with or without subsequent DNA sequencing in 10 samples of sera and liver tissues in pairs. RESULTS: Positive results were obtained using routine protocol in 4 and 9 out of 10 samples of the sera and the liver tissues respectively. The PCR products were proved to be specific using RFLP analysis with Kpn I. However, positive results were found in only 2/10 and 3/10 of samples of sera and liver tissue using DNA sequencing. The results of SNAC-PCR were the same as those of routine protocol with subsequent DNA sequencing. Furthermore, sharper electrophoresis bands were obtained. CONCLUSION: SNAC-PCR could dramatically increase the specificity of the detection of TTV DNA, especially in high background nuclear acid samples. It can be widely used in the detection of other pathogens with low seral level or in high background nuclear acid samples. The level of TTV infection might be over-evaluated by currently used TTV DNA detection when the PCR products were not confirmed by DNA sequencing.

Base Sequence↗

PubMed2001

[The binding characteristics of insulin-MTX to insulin receptor].

OBJECTIVE: It has been reported that several kinds of tumors express increased insulin receptor and the molecules of insulin can be internalized in cells and may thence enter into the nuclei mediated by insulin receptor. In this study, we investigated the receptor binding characteristics of insulin-MTX for the possibility of using insulin as a carrier for carcinoma targeted therapy by receptor mediation. METHODS: MTX(methotrexate) was covalently linked to insulin directly. The insulin-MTX conjugate was purified by polyacrylamine agarose gel electrophoresis and analysed by high performance liquid chromatography and SDS- polyacrylamine agarose gel electrophoresis. Histologically confirmed human hepatocellular carcinoma specimens were obtained from patients at surgery and immediately frozen under -80 degrees C. Cell membrane fractions were isolated by sucrose density gradient centrifugation. Competitive displacement of 125I-insulin with insulin and insulin-MTX binding to insulin receptor were carried out and the values of IC50 and Ki were calculated so as to observe the characteristics of insulin-MTX binding to insulin receptor. RESULTS: Insulin-MTX competed as effectively as insulin with 125I-insulin for insulin receptor. The values of IC50 and Ki for insulin-MTX were 93.82 +/- 19.32 nmol/L and 91.88 +/- 16.86 nmol/L respectively, while the values of IC50 and Ki for insulin were 5.01 +/- 1.24 nmol/L and 4.85 +/- 1.12 nmol/L respectively. CONCLUSION: Insulin-MTX could bind with insulin receptor with high affinity. The result demonstrates us that there is a possibility of using insulin as a carrier for carcinoma targeted therapy by receptor mediation.

Antimetabolites, Antineoplastic↗

PubMed2001

[The role of YIGSR and RGD peptides in regulating fenestrae of sinusoidal endothelial cells].

OBJECTIVE: To investigate the effects of Tye-Ile-Gly-Ser-Arg (YIGSR) and Arg-Gly-Asp (RGD) polypeptides on the fenestrae of the liver sinusoidal endothelial cells (SECs). METHODS: By in situ collagenase perfusion and two-step percoll gradient centrifugation, SECs were isolated from normal Wistar rats and cultured on collagen type I or laminin-coated coverslips. The population of SECs fenestrae and their diameters were observed using scanning electron microscopical technique; and the synthesis of collagen type IV in SECs was assessed by radio-immunoassay (RIA). RESULTS: The average number of fenestrae and their diameter in the SECs cultured on laminin-coated coverslips were significantly lower than those on collagen type I-coated coverslips. After the treatment with YIGSR pentapeptides (50 micrograms/ml) and RGD tripeptides (50 micrograms/ml) together for 48 hrs, the number and diameters of fenestrae in the SECs that grew on laminin-coated coverslips increased markedly. Meanwhile, the YIGSR and RGD peptides could significantly decrease the synthesis of collagen type IV in SECs that grew on laminin-coated coverslips. CONCLUSION: The results suggested that the YIGSR and RGD polypeptides may have an important role in regulating the morphology and function of SECs.

Animals↗

PubMed2001

[Determination of intestinal trefoil factor in burned rats by reversed-phase high performance liquid chromatography].

A reversed-phase high performance liquid chromatographic method was established for determination of intestinal trefoil factor (ITF) in burned rats. The analysis was carried out on a Hypersil C4 column (30 nm, 5 microns, 4.6 mm i.d. x 250 mm) with gradient elution of acetonitrile-trifluoroacetic acid-water solution at a flow rate of 1 mL/min and detected by a UV detector at 214 nm. The volume proportion of trifluoroacetic acid in water is 0.1% and the volume proportion of acetonitrile in mobile phase ranged from 19.5% to 42.0%. The linear range of the method was 1 mg/L-100 mg/L with relative coefficient of 0.9989. The minimum detection limit was 0.5 mg/L. The recovery of ITF added ranged between 93.95% and 105.90%. The intra-day and inter-day RSD of ITF were less than 5.33% and 6.10% respectively. This method is precise, accurate and can be used for the determination of ITF in intestinal mucosal of burned rats. Therefore, it is helpful in the research of comparing the effects of enteral feeding and parenteral nutrition on ITF expression.

Animals↗

PubMed2000

Evolution of the family of pRN plasmids and their integrase-mediated insertion into the chromosome of the crenarchaeon Sulfolobus solfataricus.

Plasmid pHEN7 from Sulfolobus islandicus was sequenced (7.83 kb) and shown to belong to the archaeal pRN family, which includes plasmids pRN1, pRN2, pSSVx and pDL10 that share a large conserved sequence region. pHEN7 is most closely related to pRN1 in this conserved region. It also shares a large variant region containing several homologous genes with pDL10, which is absent from the other plasmids. The variant region is flanked by the sequence motif TTAGAATGGGGATTC and similar duplicated motifs occur in plasmids pRN1 and pRN2, separated by a few bases. It is inferred that recombination at these sites produces the main genetic variability in the plasmid family. The conserved region of the plasmid, and duplicated copies of the motif, are also present in the genome of Sulfolobus solfataricus P2. Moreover, they are bordered by a partitioned integrase gene (int) and by a 45 bp perfect direct repeat corresponding to the downstream half of a tRNA(Val) gene. The integrase and the direct repeat are highly similar in sequence to the integrase and the chromosomal integration site (att), respectively, of the SSV1 virus, which integrates into the chromosome of Sulfolobus shibatae. Recombination at the att repeats in S. solfataricus would produce a novel plasmid, pXQ1, which carries both an intact integrase gene and a single integration site (att). This strongly suggests that the same mechanism of site-specific integration at a tRNA gene is used for both viruses and plasmids in Sulfolobus.

Attachment Sites, Microbiological↗

PubMed2000

Morphine increases susceptibility to oral Salmonella typhimurium infection.

This study examined the effect of morphine on oral infection with virulent Salmonella typhimurium. Animals were treated with a 75-mg slow-release morphine pellet followed by inoculation with salmonellae. Morphine markedly sensitized mice to oral infection, as assessed by survival, mean survival time, and colony culture. By 24 h after Salmonella inoculation, morphine-treated mice had a 105-fold difference in number of organisms in the Peyer's patches, compared with controls. The opioid antagonist naltrexone significantly blocked Salmonella colonization in Peyer's patches and reduced Salmonella burden in other organs, indicating that morphine acts at least in part via an opioid receptor-mediated pathway. The data show that morphine markedly potentiates Salmonella infection at the gastrointestinal portal of entry and enhances subsequent dissemination of Salmonella organisms. The results have implications for potentiating gastrointestinal opportunistic infections in intravenous drug abusers and in opioid-medicated postsurgical patients.

Animals↗