Search PubMed⌕ Search

Biomedical subjects

H Xu

Publications and source records attributed to H Xu.

At least 631 records · Page 35Linked to original sources
PubMed1995

[14C-urea breath test in the diagnosis of Helicobacter pylori infection in the stomach].

We developed a modified 14C-urea breath test (14C-UBT) to diagnose Helicobacter pylori (Hp) infection in 70 patients in which subjects were given 92.5 kBq (2.5 microCi) 14C-urea with 25 mg nonradioactive urea, without nutrient-dense meal. Using the mean value +3s as a cutoff value, the 20 min sample gave a sensitivity of 97.36%, a specificity of 90.00%, a positive predictive value of 97.36%, and a negative predictive value of 90.0%. Our data showed: (1) A satisfying accuracy of the modified 14C-UBT for the detection of Hp infection was obtained. (2) Taking 92.5 kBq (2.5 microCi) 14C-urea and 20 min collected sample may be of great use and to replace the previous big dose and long time methods. (3) This test may be applied routinely as a noninvasive, accurate, low cost, safe and rapid method. (4) It played an important role in reflecting the susceptibility of Hp to various drugs in vivo and monitoring the recurence of Hp.

Adult↗
PubMed1995

[Mesenteric vein thrombosis after devasculation for portal hypertension].

Six patients with mesenteric vein thrombosis (MVT) after devasculation for portal hypertension were treated by intestinal resection. Two patients had recurrence of thrombosis after the initial operations. Among 6 patients 2 survived and 4 (66.7%) died. MVT is an underappreciated, patentially lethal complication after revasculation. Three pathogenic factors after the operation may lead to thrombus formation of the portal vein, portal congestion, hypercoaguble state, and extensive ligation of portal branches. The complication commonly occurs in the recent period after devasculation. It is a characteristic manifestation of MVT that abdominal pain is out of proportion to physical findings. The most effective method is resection of infarcted bowel with sufficient length of normal bowel and its mesentery. In order to avoid a recurrence of thrombosis, postoperative anticoagulation treatment should be given.

Adult↗
PubMed1995

Transmembrane Ca2+ gradient-mediated phosphatidylcholine modulating sarcoplasmic reticulum C(a2+)-ATPase.

The sarcoplasmic reticulum (SR) C(a2+)-ATPase was purified and reconstituted into the sealed phospholipids vesicles with or without transmembrane Ca2+ gradient. The role of phospholipids, especially phosphatidylcholine (PC), in the modulation of C(a2+)-ATPase by transmembrane Ca2+ gradient was investigated. The results are as follows. (i) Incubated with phospholipids, the enzyme activity of the delipidated C(a2+)-ATPase is inhibited by Ca2+ and the highest inhibition is observed in the presence of PC. (ii) When there exists a transmembrane Ca2+ gradient (higher Ca2+ concentration inside vesicles, 1,000 mumol/L:50 mumol/L, similar to the physiological condition), the inhibition of C(a2+)-ATPase by transmembrane Ca2+ gradient can be only observed in the vesicles containing PC:PE, but not in those containing PS:PE or PG:PE. The highest inhibition is obtained at a 50:50 molar ratio of PC:PE (iii) By comparing the effects of PC differing in acyl chains, higher inhibition of C(a2+)-ATPase is observed in vesicles containing DPPC:PE and DOPC:PE, while no inhibition in DMPC:PE vesicles (iv) If the transmembrane Ca2+ gradient is in the inverse direction, the enzyme activity of C(a2+)-ATPase is inhibited whenever reconstituted with acidic or neutral phospholipids.

Animals↗
PubMed1995

[Screening for gestational diabetes with capillary blood glucose].

Two hundred and twenty 3rd trimester pregnant women were randomly selected to perform 50 g oral glucose tolerance screening test. Simultaneously, both capillary and venous blood samples were obtained one hour after the glucose load. A high correlation between capillary and venous glucose levels was found (r = 0.87, P < 0.01). From the receiver operator characteristic curve, it was found that the capillary glucose value of 9.1 mmol/L might be defined as abnormal threshold value for 100g oral glucose tolerance test (OGTT). The consistent rate between capillary and venous glucose test was 91.8%. In 100g OGTT, of 43 cases whose venous glucose were > or = 7.8 mmol/L, 11 were diagnosed as gestational diabetes mellitus (GDM). All of these 11 patients had capillary glucose > or = 9.1 mmol/L. This results suggest that the capillary blood glucose test may be feasible for screening of gestational diabetes.

Adult↗
PubMed1995

[Studies on comprehensive evaluation of toxic hazard in low-concentration benzene pollution].

Early adverse effects of exposure to benzene in a concentration less than 32 mg/m3 on the employees' health were comprehensively evaluated with WHO neurobehavioral core test battery, cytokinesis-block micronucleus assay for peripheral blood lymphocytes, determination of serum level of sialic acid and T-lymphocyte assay with alpha-naphthyl acetate esterase (ANAE) stain. Results revealed emotional irritability could be found in the exposed employees and 24% of them showed an abnormal percentage of micronuclei formation and increased serum level of sialic acid.

Adult↗
PubMed1995

Inhibition of platelet aggregation by an SLE-derived human hybridoma autoantibody against an activation-dependent antigen.

Anti-platelet autoantibodies may be responsible for hematological complications in patients with systemic lupus erythematosus (SLE), but the mechanisms by which these antibodies cause abnormal hemostasis remain unknown. In the present study, using fluorescence activated cell sorter (FACS) analysis, we demonstrate that an SLE-derived human hybridoma autoantibody, 9604, recognizes a surface antigen expressed on platelets activated by ADP, calcium ionophore A23187, or phorbol myristate acetate (PMA), showing saturation with approximately 2,000 antibody molecules bound per platelet and a Kd of 41 nM. The binding of 9604 to activated platelets was significantly inhibited by EDTA, indicating partial dependence on divalent cations. It did not appear to be dependent on platelet secretion, nor did it directly affect alpha-granule or dense granule secretion. The protein antigen responsible for the binding of 9604 to activated platelets was characterized by Western blot and immunoprecipitation and shown to have a native molecular weight (M. W.) of greater than 400,000, with a 32,000 M. W. subunit (p 32). Antibody 9604 had little or no effect on the shape change and the initial rate of primary aggregation of normal platelets. In contrast, 9604 inhibited secondary aggregation of stirred platelet suspensions (IC50 < or = 1 nM) following activation by ADP, thromboxane A2 mimetic U46619, or calcium ionophore A23187, but not PMA or thrombin. The inhibition of large platelet aggregate formation (secondary aggregation), with a major shift to smaller microaggregates and singlets, was confirmed by direct particle count and sizing studies. The functional inhibition of platelet aggregation by an SLE-derived human hybridoma autoantibody in vitro suggests one potential mechanism that may play a role in the hemostatic disorders found in SLE.

Adenosine Diphosphate↗
PubMed1995

Characteristics of an established retinoblastoma cell line HXO-Rb44.

PURPOSE: To study the retinoblastoma cell culture and to establish a new retinoblastoma cell line. METHODS: 22 retinoblastomas were cultured by using the method of single cell suspension. Characteristics of the cultured cells were studied in the following programs: tumor cell morphology in vitro, electron microscopic, growth curve, cloning in soft agar, immunohistochemistry, karyotype and tumorigenicity. RESULTS: 22 retinoblastomas were cultured successfully in vitro, only a continued cell line HXO-Rb44 was established (more than 3 years). The characteristics of this cell line are that it grew as a suspension of round cell in graps like clusters in vitro, its population doubling time was 44 hours, and it could be cloned in soft agar. Histopathologic and ultrastructured pictures showed the characteristics of Rb. HXO-Rb44 cell was positive to NSE and negative to GFAP in immunohistochemical staining. A subcutaneous injection of HXO-Rb44 cells produced a retinoblastoma in BALB/C athumic nude mice. CONCLUSIONS: HXO-Rb44 has the characteristics of retinoblastoma and is a new retinoblastoma cell line. It is a useful material for study this tumor both in basic and clinical fields.

Animals↗
PubMed1995

[Preliminary survey on the traditional Chinese drug: shell of abalone or sea-ear].

According to an on-site survey of the commercial medicinal materials in China, it is demonstrated that the shells of abalone or sea-ear consist of nine types. Their original animals are Haliotios diversicolor, H. discus hannai, H. ovina, H. asinia, H. ruber, H. laevigata, H. semistrata, H. midae and H. cracherodii. Three of these types namely, H. semistrata, H. midae and H. cracherodii are not included in the Chinese Pharmacopeia. Furthermore, most of the shells of abalone or sea-ear presently on market are Haliotios ruber and H. discus hannai.

Animals↗
PubMed1995

[Hemodynamic changes in portal system after transjugular intrahepatic portosystemic shunts (TIPS)].

In this study portal venous flow (PVF), splenic venous flow (SPVF), hepatic artery volume (HAV), and portal pressure were measured before and after TIPS in 11 patients with portal hypertension. The results were compared with those of normal controls. In the normal controls PVF averaged 947.2 +/- 133.4ml/min, SPVF 239.6 +/- 116.3ml/min, and HAV 241.6 +/- 78.8ml/min. In the TIPS group before and after TIPS, PVF was 883.2 +/- 233.4ml/min vs. 958.7 +/- 185.2ml/min; SPVF was 448.9 +/- 111.6ml/min vs. 333.1 +/- 101.5ml/min; HVP was 225.3 +/- 122.7ml/min vs. 249.3 +/- 103.8ml/min. Portal pressure dropped from 3.94kPa +/- 0.46 to 2.52 +/- 0.60kPa after TIPS. We conclude that in patients after TIPS portal pressure drops blood flow in the truck of the portal vein increases, flow of hepatic tissue decreases, and blood flow in splenic vein decreases. Blood flow in hepatic aftery was not significantly changed.

Adult↗
PubMed1995

[Effects of a platelet-activating factor antagonist ONO-6240 on antigen induced eosinophil infiltration into the airways].

An in vivo mouse model of allergic bronchial asthma was developed to investigate the effects of a platelet activating factor antagonist ONO-6240 on eosinophil (EOS) recruitment into the mouse airway. In the present study, no EOS could be found in bronchoalveolar lavage fluid (BALF) from normal control mice. However, chronic ovalbumin challenge of sensitized mice induced significant bronchoalveolar eosinophilia (9.68 +/- 0.72 x 10(8)/L). In three groups of mice treated intraperitoneally with different doses of ONO-6240 (0.1, 1.0, 10.0 mg/kg), the medication produced 42.1% (5.60 +/- 0.97 x 10(8)/L, P < 0.01), 58.8% (3.99 +/- 0.84 x 10(8)/L, P < 0.01), and 72.6% (2.65 +/- 0.71 x 10(8)/L, P < 0.01) inhibition, respectively, of the antigen-induced influx of EOS into BALF. It was found that the prevention of EOS infiltration into airway with ONO-6240 was accompanied by decrements of both interleukin (IL)-5 and IL-2 levels. These data indicated that ONO-6240 prevented airway eosinophilia by inhibiting production of IL-5 and IL-2. Our results suggested that ONO-6240 may be of value in treating human asthmatic patients.

Animals↗
PubMed1994

Abrogation of baboon natural xenoantibody to pig splenocytes by DL-penicillamine.

Natural xenoantibodies are believed to be IgM in nature and are known to play a critical role in the hyperacute rejection of distantly related xenografts. The purpose of this study was to determine whether the reducing agent DL-penicillamine could inactivate baboon natural xenoantibodies to pig splenocytes. Pooled baboon serum was treated with varying concentrations of DL-penicillamine over different lengths of time and a complement-mediated cytotoxicity assay was used to determine the reactivity of baboon natural xenoantibodies to pig splenocytes. A whole-cell ELISA assay was used to assess the binding of both IgG and IgM xenoantibodies to pig splenocytes. In addition, DL-penicillamine-treated serum was dialyzed to assess its potential clinical application. These in vitro experiments indicate that both IgM and IgG baboon natural xenoantibodies bind to pig splenocytes, but only IgM xenoantibody is cytotoxic. The binding of baboon natural IgM xenoantibody can be eliminated, and the cytotoxicity of IgM xenoantibody markedly reduced by DL-penicillamine treatment despite continued binding of IgG xenoantibody to pig splenocytes. In addition, DL-penicillamine can be dialyzed, suggesting that it may be an efficacious clinical treatment, the toxicity of which can be regulated with hemodialysis.

Animals↗
PubMed1994

A marked change of receptor affinity of the 2-methyl-5-(3-hydroxyphenyl)morphans upon attachment of an (E)-8-benzylidene moiety: synthesis and evaluation of a new class of sigma receptor ligands.

The (E)-8-benzylidene and (E)-8-(3,4-dichlorobenzylidene), 7-ketone derivatives, 5 and 6, of the synthetic opiate 2-methyl-5-(3-hydroxyphenyl)morphan [5-(3-hydroxyphenyl)-2-methyl-2-azabicyclo[3.3.1]nonane, 1], were synthesized from the 7-ketone derivatives 2 or 4 via the Claisen-Schmidt reaction. The corresponding enantiomers of 5 and 6 were obtained in > 99% optical purity from the optical isomers of 4, resolved with the O,O'-dibenzoyltartaric acids. The absolute configurations of the enantiomers of 4 were determined by conversion, via Clemmensen reduction, to the enantiomers of 1, the configurations of which are known. The determination of the regioisomer and configurational isomer of 5, with respect to the introduced benzylidene group, was determined from a single-crystal X-ray analysis. 1H NMR data was used to confirm that 6 possessed the same configuration as 5. Radioreceptor binding studies in rat and guinea pig brain preparations revealed that (-)-(1S,5S)-5 displayed an 11-fold decrease in affinity for the opioid mu receptor and an increase in affinity for sigma receptors of 81-fold (low nanomolar affinity) relative to the ketone precursor (+)-(1S,5S)-4. An analogous, albeit less dramatic, trend was seen with compound (-)-(1S,5S)-6. Compounds (-)-(1S,5S)-5 and (-)-(1S,5S)-6 are distinct from the typical sigma-opiates in that they have very low affinity for either PCP sites or muscarinic receptors. The high affinity and selectivity of these novel sigma receptor ligands suggests that they will be valuable for the elucidation of the functional roles of sigma receptors.

Analgesics↗
PubMed1994

Prosomatostatin processing in permeabilized cells. Endoproteolytic cleavage is mediated by a vacuolar ATPase that generates an acidic pH in the trans-Golgi network.

To investigate the relationship between prohormone processing and sorting of mature polypeptides into nascent secretory vesicles, we recently developed a permeabilized cell system that supports both these reactions (Xu, H., and Shields, D. (1993) J. Cell Biol. 122, 1169-1184). Rat anterior pituitary GH3 cells expressing high levels of prosomatostatin (proSRIF) were incubated at 20 degrees C; this temperature prevented exit from the trans-Golgi network and inhibited proSRIF processing. Following the 20 degrees C block, the cells were mechanically permeabilized and incubated at 37 degrees C, and proSRIF processing was determined. Cleavage of proSRIF to the mature hormone required ATP hydrolysis and was inhibited by chloroquine, a weak base, or carbonyl cyanide m-chlorophenylhydrazone, a protonophore. This suggested that a proton gradient and/or an acidic pH facilitated by a vacuolar H(+)-ATPase was required for prohormone processing. We have now utilized the permeabilized cell system in conjunction with the antibiotic bafilomycin A1, a specific inhibitor of vacuolar H(+)-ATPases, to elucidate the role of acidic pH in prohormone processing. Here we report that (i) proSRIF processing was inhibited in vivo and in vitro by low concentrations of bafilomycin A1, confirming the involvement of a vacuolar type ATPase in prohormone processing; (ii) the ATP requirement for processing could be circumvented in vitro by incubating permeabilized cells at acidic pH in the presence of protonophores, indicating that an acidic pH rather than a H+ gradient is necessary for processing; and (iii) a pH of between 6 and 6.2 in the trans-Golgi network was optimal for proSRIF cleavage. We also demonstrate that prohormone convertase 2 exhibited temperature-dependent activity in which proSRIF processing was inhibited at 20 degrees C in vitro. This result explains our previous observation that prohormone processing is inhibited when intact cells are incubated at 20 degrees C.

Animals↗