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H Xue

Publications and source records attributed to H Xue.

At least 73 records · Page 4Linked to original sources
PubMed1998

Identification of major phylogenetic branches of inhibitory ligand-gated channel receptors.

The gene superfamily of ligand-gated ion channel (LGIC) receptors is composed of members of excitatory LGIC receptors (ELGIC) and inhibitory LGIC receptors (ILGIC), all using amino acids as ligands. The ILGICs, including GABAA, Gly, and GluCl receptors, conduct Cl- when the ligand is bound. To evaluate the phylogenetic relationships among ILGIC members, 90 protein sequences were analyzed by both maximum-parsimony and distance matrix-based methods. The strength of the resulting phylogenetic trees was evaluated by means of bootstrap. Four major phylogenetic branches are recognized. Branch I, called BZ, for the majority of the members are known to be related to benzodiazepine binding, is subdivided into IA, composed of all GABAA receptor alpha subunits, and IB, composed of the gamma and epsilon subunits, which are shown to be tightly linked. Branch II, named NB for non-benzodiazepine binding, and consisting of GABAA receptor beta, delta, pi, and rho subunits, is further subdivided into IIA, containing beta subunits; IIB, containing delta, and pi subunits; and IIC, containing rho subunits. Branch IIIA, composed of vertebrate Gly receptors, is loosely clustered with Branch IIIB, composed of invertebrate GluCl receptors, to form Branch III, which is designated NA for being non-GABA responsive. Branch IV is called UD for being undefined in specificity. The existence of primitive forms of GABAA receptor non-beta subunits in invertebrates is first suggested by the present analysis, and the identities of sequences p25123 from Drosophila melanogaster, s34469 from Lymnaea stagnalis, and u14635 and p41849 from C. aenorhabditis elegans are determined to be different from their previously given annotations. The proposed branching classification of ILGICs provides a phylogenetic map, based on protein sequences, for tracing the evolutionary pathways of ILGIC receptor subunits and determining the identities of newly discovered subunits on the basis of their protein sequences.

Amino Acid Sequence↗
PubMed1998

Corrosion behavior of copper in a copper bearing intrauterine device in the presence of indomethacin.

As an improvement to the use of the copper bearing intrauterine device, indomethacin has been introduced to reduce the incidence of bleeding after insertion of the device. The effects of indomethacin on copper corrosion were studied in vitro in simulated uterine fluid. Electrochemical polarization resistance measurements indicated that indomethacin powder slightly increased the corrosion rate of copper if pH of the fluid was not under control and it did not change the corrosion rate if pH was adjusted daily to maintain some constancy. The experimental results for medication by indomethacin-releasing Silastic were basically the same as those with powdered indomethacin. X-ray diffraction showed that only cuprous oxide was formed on the copper substrated surface and that indomethacin did not affect the corrosion products. As scanning electron microscopy demonstrated, however, in the presence of indomethacin the oxide particles formed were found to be more coarse and dense than in the absence of indomethacin.

Body Fluids↗
PubMed1998

Effect of stainless steel on corrosion behavior of copper in a copper-bearing intrauterine device.

Some copper-bearing intrauterine devices (Cu-IUDs) consist of pure copper and stainless steel. Corrosion of copper in the Cu-IUD was anticipated to be affected by galvanic action due to electrical contact between these two metals. Electrochemical measurements were carried out in physiological saline with or without indomethacin, which was introduced for bleeding control. In the copper/stainless steel couple, the open-circuit potential of stainless steel was found to play a decisive role. In most cases, when stainless steel was in the passive state and acted as the cathode, the contact accelerated copper corrosion. In addition, the area ratio of stainless steel to copper altered copper corrosion behavior. The larger the area of stainless steel, the greater the acceleration of copper corrosion. It was noted that the stainless steel surface might be activated due to improper handling of the IUD. In this case, copper became the cathode of the couple and its corrosion was suppressed.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1998

A major component approach to presenting consensus sequences.

MOTIVATION: Summarizing and displaying the information contained in a set of aligned sequences is an important aid to identifying patterns within the sequences. A variety of forms of consensus sequences have been used previously to provide this information. However, these methods can cause a loss of information or introduce ambiguities into the consensus sequence, and some graphical approaches may become difficult to interpret due to visual distortion. RESULTS: We have developed a method to present a more precise and graphically clear view of a consensus sequence by using an approach based on defining the major components at each position in a sequence set. The major components are given in an ordered list and their frequencies are shown as histograms which can be colour coded to reflect conservative groupings. Minor components, a one-line character-based consensus sequence and information statistics can also be presented. As well as identifying the dominant sources of variation and conservation in the sequence set, the method also enables similarities and differences between subgroups of a sequence set to be readily assessed. AVAILIABILITY: On request from the authors. CONTACT: bcsmith@usthk.ust.hk, hxue@usthk. ust.hk

Amino Acid Sequence↗
PubMed1998

Preparation of highly purified hemoglobin by affinity elution.

The large scale production of recombinant hemoglobin (Hb) from microorganism or transgenic hosts for Hb-based blood substitutes places utmost emphasis on purity. In the present study, a high-resolution, convenient and inexpensive purification method is developed for purification of Hb from mixtures containing E. coli extract and bovine serum. This method is based on affinity elution by pyrophosphate (PPi) of Hb adsorbed on an FPLC column of the anion exchanger Toyopearl DEAE-650M. Compared to pH elution or NaCl elution, PPi elution makes possible the preparation of Hb of much higher purity. A procedure combining pH elution and PPi elution sequentially using a single column proves particularly valuable. The purification method is also applicable to the purification of cyanomet-Hb (CNHb+).

Chromatography, Affinity↗
PubMed1998

Protective immunity in mice elicited by living infective third-stage hookworm larvae (Shanghai strain of Ancylostoma caninum).

OBJECTIVE: To elucidate the mechanisms of protective immunity in mice elicited by living hookworm (Ancylostoma caninum third-stage infective larvae (L3). METHODS: The number of migrating infective larvae recovered from the lungs was used as an endpoint for vaccine immunity. The timing of maximal L3 lung entry was determined by counting the number of lung larvae at several time points after infection with 500 or 1000 L3. Mice were immunized either orally or subcutaneously with 500 L3, followed by two boosts of L3 once every two weeks. The immunized mice were challenged orally with 500 L3 one week after the final boost. To evaluate the protective immunity, the number of L3 recovered from the lungs of the immunized mice during the time of maximal larval entry was compared with that of controls. Host immunity was also evaluated by comparing circulating anti-L3 antibodies between immunized and controlled mice, using both enzyme immunoassays and immunoblotting techniques, and by lung histopathology. RESULTS: The peak time of larval entry into the lungs occurred 48 hours after infection. Mice immunized either orally or subcutaneously with L3 exhibited a marked reduction (90.2% and 86.2% respectively) in the number of recovered lung larvae in comparison to controls (P < 0.01). The protection might be associated with circulating anti-L3 antibodies, including antibodies directed against 132-200 kDa L3 antigens, as well as three major antigens ranging from 28 to 51 kDa. Larvae migrating through the lungs of vaccinated mice showed cuticular damages accompanied with host-inflammatory cell invasion. CONCLUSIONS: Immunization with living L3 protects mice against lung invasion after challenged with hookworm infection. Vaccine immunity is associated with circulating antibodies against L3 antigens and lung inflammatory responses. The mouse model is potentially useful for developing a hookworm vaccine.

Ancylostoma↗
PubMed1998

Opening blood-brain-barrier by intracarotid infusion of papaverine in treatment of malignant cerebral glioma.

OBJECTIVE: To find an effective method for the treatment of malignant cerebral glioma by opening the blood-brain-barrier (BBB). METHODS: The concentration of methotrexate (MTX) in tumor was measured in 18 patients with cerebral glioma, and 155 patients with malignant glioma were treated by intracarotid infusion of papaverine and Bis-chloronitrosourea (BCNU). RESULTS: After intracarotid infusion of papaverine for reversible opening of BBB, the MTX concentration in tumor tissue was 1810 +/- 380 ng/g, higher than that in patients without papaverine infusion (997 +/- 126 ng/g). Eighty-nine patients with glioblastoma and 66 patients with anaplastic astrocytoma received intracarotid infusion of papaverine and BCNU (250 mg) for an average of 2.14 times. The mean survival time of these patients was 114.5 weeks, median survival time was 140 weeks, and five-year survival rate was 22.97%. CONCLUSION: The combined chemotherapy with papaverine and BCNU through intra-arterial infusion is simple, safe and effective in treating malignant cerebral glioma so long as the tumor is sensitive to the drugs.

Adolescent↗
PubMed1998

[Comparative observation on the efficacy of several test/probe systems for detecting schistosome circulating antigen].

AIM: To compare the efficacy of 5 test/probe systems for the detecting of schistosomal circulation antigen (SCA) in sera from infected rabbits. METHODS: Nine rabbits were infected with monosexual cercariae (either male or female), 7 rabbits were infected with bisexual cercariae as controls. Blood samples were collected periodically post infection (p.i). 15 rabbits were infected each with 250 bisexual cercaria and divided into 3 groups, 2 groups were treated with allyl thiourea (295-590 mg/kg) from 19 d or 46 d respectively, to inhibit their egg formation. One untreated group was used as control. Blood samples were collected weekly until 8 wk post infection. SCA detecting methods include (1) dot-ELISA/McAb anti-surface membrane antigen of adult worms (8SE4), (2) dot-ELISA/McAb anti-CCA (3D10), (3) Sandwich dot-ELISA/McAb anti-egg antigen (MG2), (4) Sandwich-ELISA/McAb anti-egg antigen (2H10), (5) Sandwich-ELISA/McAb anti-CAA (1B10). RESULTS: Using method (1) all of the 18 rabbits infected with monosexual cercariae were negative. Using method (2) only 1 rabbit harboured 133 male worms showed positive. Using method (5) no SCA were detected in sera from female cercariae-infected rabbits but 3 out of 9 male cercariae-infected rabbits showed positive reaction. SCA detecting results from rabbits treated with allyl thiourea: both method (1) and (3) showed negative in rabbits treated from 19 d (p.i.) but all gave positive reaction in 6-7 wk in rabbits treated from 46 d (p.i.). There were all negative detected by using method (4) and all positive at 6 wk (p.i.) detected by method (5) in rabbits of 3 groups whether treated or non-treated. CONCLUSION: Various test/probe systems have different efficacy in detecting SCA but (5) of the methods (1)(2) tests/probe systems could not detect SCA in rabbits with single female cercariae infection. From the egg formation inhibition study, the SCA detected by McAb 8SE4 dot-ELISA might be related to egg maturation. Whether the surface membrane antigen of adult worm has common antigenic component with egg antigen remains to be studied.

Animals↗
PubMed1998

[Morphological observation on Blastocystis hominis].

AIM: To observe the morphology of Blastocystis hominis. METHODS: The morphology of Blastocystis hominis found in the fecal specimens from school children and diarrheal cases was examined by using normal saline smear, iodine stain and iron-hematoxylin staining method in Ali, Xizang Autonomous Region and Xinjiang Autonomous Region. RESULTS: The morphology of Blastocystis hominis was found to include four types, namely vacuolized, granular, amoeboid and binary fission. CONCLUSION: The vacuole type was the most often seen and accounted for 84% of all 4 types. Blastocystis hominis infection was often found to be associated with Entamoeba coli and other intestinal protozoa, leading to diarrhea in these patients.

Adult↗
PubMed1998

[Detection of Brugia malayi larva in mosquito vector by PCR and PCR-ELISA].

AIM: To develop sensitive, specific, simple assays for the detection of Brugia malayi larva in mosquito vectors. METHODS: The optimum conditions for PCR and PCR-ELISA were determined. With dissected larvae, detection limits and as well as specificities of the two assays were worked out. The optimized assays were then tested with infected and non-infected mosquito vectors, Anopheles sinensis. RESULTS: Both PCR and PCR-ELISA detected DNA equivalent to a single L1-stage larva(L1). While the actual detecting limits of the two, as estimated and titrated respectively, reached to 1/10 and 1/100 of a L1. When the two assays were used to detect the larvae isolated from 113 infected A. sinensis, all gave specific bands and positive reactions. However, trials on direct amplifications with crude extracts of infected mosquito vectors consistently failed to give specific bands upon electrophoresis and negative results in PCR-ELISA as well. CONCLUSION: Both PCR and PCR-ELISA were preliminarily established for the detection of isolated B. malayi larva in mosquito vector, which proved to be sensitive, specific and easy to manipulate.

Animals↗
PubMed1997

Farnesol inhibits L-type Ca2+ channels in vascular smooth muscle cells.

Earlier experiments with animal and human arteries have shown that farnesol, a natural 15-carbon (C15) isoprenoid, is an inhibitor of vasoconstriction (Roullet, J.-B., Xue, H., Chapman, J., McDougal, P., Roullet, C. M., and McCarron, D. A. (1996) J. Clin. Invest. 97, 2384-2390). We report here that farnesol reduced KCl- and norepinephrine-dependent cytosolic Ca2+ transients in fura-2-loaded intact arteries. An effect on Ca2+ signaling was also observed in cultured aortic smooth muscle cells (A10 cells). In these cells, farnesol reduced KCl-induced [Ca2+]i transients and mimicked the inhibitory effect of Ca2+-free medium on the [Ca2+]i response to both 12,13-phorbol myristate acetate, a protein kinase C activator, and thapsigargin, a specific endoplasmic reticulum ATPase inhibitor. Perforated patch-clamp experiments further showed in two vascular smooth muscle cell lines (A10 and A7r5), a reversible, dose-dependent inhibitory effect of farnesol on L-type Ca2+ currents (IC50 = 2.2 microM). Shorter (C10, geraniol) and longer (C20, geranylgeraniol) isoprenols were inactive. L-type Ca2+ channel blockade also occurred under tight (gigaohm) seal configuration using cell-attached, single-channel analysis, thus suggesting a possible action of farnesol from within the intracellular space. We finally demonstrated that farnesol did not affect Ca2+-sensitive pathways implicated in smooth muscle contraction, as tested with alpha-toxin permeabilized arteries. Altogether, our results indicate that farnesol is an inhibitor of vascular smooth muscle Ca2+ signaling with plasma membrane Ca2+ channel blocker properties. The data have implications for the endogenous and pharmacological regulation of vascular tone by farnesol or farnesol analogues.

Animals↗
PubMed1997

Sequence profiles of immunoglobulin and immunoglobulin-like domains.

Immunoglobulins (Ig) are highly modular proteins, consisting of variable and constant domains, which have clear, conserved sequence patterns. These sequence patterns have allowed T-cell receptor (TCR) and major histocompatibility complex (MHC) molecule domains, as well as some cell adhesion, cell surface receptor and muscle protein domains, to be identified as forming a superfamily of related proteins together with the Ig-domains. The domains of these proteins have been grouped into four sets: variable (V-set), constant-1 (C1-set), constant-2 (C2-set) and intermediate (I-set). X-ray and NMR studies have shown that these domains form a Greek-key beta-sandwich structure with the sets differing in the number of strands in the beta-sheets as well as in their sequence patterns. The conserved sequence elements in the major sets of Ig and Ig-like molecules have previously been reported as general sequence profiles. This work examines the variability within these sets. Detailed sequence profiles and consensus sequences for these sets and groups have been constructed and a novel form of presentation has been developed to overcome some of the drawbacks of current methods of presenting consensus sequences. The profiles that were constructed allow a comparison of the similarities and differences among the sets of Ig and Ig-like sequences and provide a means by which sequences can be tested for compatibility with Ig-like sequence motifs. As well, the sequence separations of the main residues in the characteristic "pin" structure of Ig-like molecules were examined for variation among the groups. From the profiles constructed here, measures of the degree of conservation within the groups of molecules were determined. These measures were used to assist in a reconsideration of possible evolutionary pathways between the major structural groups of the Ig-superfamily.

Amino Acid Sequence↗
PubMed1997

Chemical modifications of Bacillus subtilis tryptophanyl-tRNA synthetase.

A concerted conformational change in Bacillus subtilis tryptophanyl-tRNA synthetase (TrpRS) was evident from previous fluorescence on the quenching of the single Trp residue Trp-92 in the 4FTrp-AMP complexed enzyme. In this study, chemical modifications of the B. subtilis TrpRS were employed to further characterize this conformational change, with the single Trp residue serving as a marker for monitoring the change. Modifications of the enzyme by means of the Trp-specific agent N-bromosuccinimide (NBS) or 3-bromo-3-methyl-2-(2-nitrophenylmercapto)-3H-indole (BNPS-skatole) inactivated the enzyme in accord with the essential role of Trp-92, as identified previously by site-directed mutagenesis. ATP sensitized TrpRS toward inactivation by NBS and BNPS-skatole, which suggested a conformational change that resulted in greater accessibility of Trp-92 toward modifications. In contrast, the cognate tRNATrp substrate exerted a specific protective effect against inactivation by both of the reagents, indicating that the TrpRS-tRNATrp interaction reduces the accessibility of Trp-92 under our experimental conditions. By comparison, modification of sulfhydryl groups by means of iodoacetamide did not reduce TrpRS activity. Observations on Trp-specific modification and substrate protection effects are discussed in the context of the Bacillus stearothermophilus TrpRS crystal structure.

Bacillus subtilis↗
PubMed1997

[Reference values for biological parameters in occupational and environmental medicine].

Biological parameters are extensively used in occupational and environmental medicine. They are traditionally evaluated by comparison with normal range. Since 1970's, with the growing skepticism about normal range and researches' progress, the replacing notion of reference values and related theory had gradually come into being with the one which is the most representative, published by International Federation of Clinical Chemistry and International Committee for Standardization in Haematology. This paper introduces those results with emphatic discussion on data processing and statistical procedures. The process of establishing reference limits is illustrated by an example and issues on reference and decision limits, reference band, multivariate reference values are also briefly addressed.

Environmental Medicine↗
PubMed1997

[The role of calcium on parotid cell differentiation and secretion in vitro].

To study the role of calcium on parotid cell differentiation and secretion, high extracellular calcium was used to treat the parotid gland cells in culture. Immunohistochemical staining was applied to examine the expression of proteins involved in cell-cell interaction, cell differentiation and parotid gland secretary proteins. The results demonstrated that the expression of CAM and Cx32 increased and more cells had positive reaction to c-jun oncoprotein. No effect of calcium on the expression of EGF-gamma, c-fos, alpha-amylase and PRP was observed. The data indicate that extracellular calcium play an important role on cells differentiation. However, it does not affect the cell secretion.

Animals↗
PubMed1997

[Quantitative study of calcitonin gene methylation in myelodysplastic syndromes].

OBJECTIVE: To investigate the role of calcitonin gene hypermethylation in the transformation from myelodysplastic syndromes (MDS) to acute myeloid leukemias (AML). METHODS: The methylation rate of calcitonin gene (CTMR) in the genomic DNA extracted from bone marrow cell of 27 MDS patients and 6 AML patients with antecedent MDS were studied by PCR amplification of Hpa I digested DNA, with external reference of undigested and Msp I digested DNA and internal reference of 112bp fragment containing N-ras-61. Intensity of silver-stained PCR products was measured by densitometer and analysed using the computer program. RESULTS: The CTMR was significantly higher in MDS (33.65% +/- 23.37%) than in control group (P<0.001), in 9 RAEB(T) (58.35% +/- 17.44%) than in the control and RA groups. Five RA patients who have survived three to ten years without leukemia, have a normal CTMR. Seven of 8 RAEB(T) patients who had a high CTMR of more than 30% evolved into AML in two months. CONCLUSION: CTMR might be a useful marker for predicting the evolution of MDS into AML.

Adolescent↗
PubMed1997

[Analysis of clonality with immunoglobulin heavy chain gene rearrangement fingerprinting map in childhood acute lymphoblastic leukemia].

OBJECTIVE: To investigate the types of the immunoglobulin heavy chain (IgH) gene rearrangement and the co-existing clones in childhood acute lymphoblastic leukemia (ALL). METHODS: Polymerase chain reaction (PCR) amplification and single-strand conformation polymorphism (SSCP) were used to construct the IgH-PCR-SSCP gene fingerprinting. RESULTS: Of the 34 gene fingerprinting maps obtained from newly diagnosed ALL, 9 (32.14%) were one allelic rearrangement and 15 (53.75%) were biallelic in mono-clonal rearrangements. Four cases (14.29%) with high white cell count and precursor-B immunophenotype were oligoclonal rearrangements. CONCLUSION: There were multiple IgH bi-allelic rearrangements and co-existing clones in childhood ALL.

Adolescent↗