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Biomedical subjects

G Xu

Publications and source records attributed to G Xu.

At least 361 records · Page 20Linked to original sources
PubMed1997

Studies on efficacy of praziquantel and mebendazole-medicated salt in treatment of Echinochasmus fujianensis infection.

The therapeutic effect of praziquantel and mebendazole-medicated salt has been studied in 109 cases with Echinochasmus fujianensis infection. These cases were randomly divided into four groups: 2 groups with a single dose of praziquantel 5 mg/kg or 2.5 mg/kg; and other 2 groups with mebendazole 800mg or 400 mg in 10d table salt. Four weeks after treatment, the egg negative conversion rates were 100%, 92.3%, 85.2% and 71.4% respectively, the egg reduction rates were 84.8-100%, and side-effects were mild. The symptoms caused by infection such as abdominal pain, diarrhea, distension and anorexia were obviously relieved. These data indicated that praziquantel is the drug of choice in the treatment of Echinochasmus fujianensis. The dosage is only 2.5 mg/kg, and its egg negative conversion rate and reduction rate reach 92.3% and 95.4%, respectively. For convenience, the dosage can be made according to their age. Children under 12 take half a tablet (100 mg), and one tablet (200 mg) for those over 12. This dosage is approximately equal to 2.5-5.0 mg/kg. Although the efficacy of mebendazole is lower than praziquantel, its egg negative conversion rate also reaches 71.4-85%. Mebendazole-medicated salt can be used for treating Echinochasmus fujianensis infection as the presence of co-infection with nematodes.

Adolescent↗
PubMed1997

Clinical significance of serum 7S collagen and type VI collagen levels for the diagnosis of hepatic fibrosis.

OBJECTIVE: To measure serum 7S collagen (7S-C) and type VI collagen (VI-C) levels by radioimmunoassay (RIA) in Chinese patients with various liver disorders and in CCl4-treated SD rats, and to investigate the significance of the elevated levels of serum 7S-C and VI-C. METHODS: Serum 7S-C and VI-C levels were measured in 40 healthy control subjects, 168 patients with various liver disorders and non-hepatic diseases, and 52 CCl4-treated SD rats by using RIA which was developed in our hospital. RESULTS: Serum 7S-C and VI-C were significantly elevated in patients with chronic active hepatitis (CAH), liver cirrhosis (LC), hepatic cellular carcinoma (HCC) (P < 0.01 respectively), chronic persistent hepatitis (CPH), and some with non-hepatic diseases (P < 0.05). Serum 7S-C, serum laminin and hyaluronic acid were well correlated. Serum 7S-C and VI-C were not closely correlated. Both collagens were correlated with serum albumin/globulin ratio, aminotransferase and total bilirubin, not with alkaline phosphatase. In CCl4-treated SD rats, serum 7S collagen and type VI collagen levels were correlated with the degree of hepatic fibrosis. CONCLUSIONS: Serum 7S collagen and type VI collagen are useful markers for diagnosing liver fibrosis. And the combined measurement of IV-C, VI-C and other markers of connective tissue metabolism or biochemical data seems to provide additional information to predict progressive hepatic fibrosis.

Animals↗
PubMed1997

[Experiment and clinical application of squeezing technique in venous crisis after replantation of finger].

In search of a new method for treating venous crisis after replantation of the finger, the effect of instantaneous, quick and forceful squeezing on the belly of replanted finger (the so-called SQUEEZINGG TECHNIQUE) was studied. In the animal experiment, 20 SD rats were used. The femoral veins and arteries were separated in order to measure the venous pressure. The result showed that the venous pressure was (8.33 +/- 1.29) x 10(-2) kPa in normal condition, (20.61 +/- 2.34) x 10(-2) kPa in the condition simulating venous crisis and (73.9 +/- 5.74) x 10(-2) kPa on carrying out the squeezing technique. The second part of the experiment was performed on ten human fingers which were amputated because of trauma or other diseases. One of the arteriae digitales palmares propriae and two of its accompanied veins were disected, and all other blood vessels were ligated. The artery was irrigated with normal saline at a pressure of 12 kPa. When both veins were left open, the venous pressure was (1.32 +/- 0.17) kPa; (4.29 +/- 0.49) kPa, when both were ligated; and (16.88 +/- 5.25) kPa when the squeezing technique was applied at the time venous crisis developed. From May 1991 to May 1996, this method was used for 43 times in 25 cases (35 fingers) with venous crisis after replantation. It was successful for 39 times in 21 cases (30 fingers). It was very important that the performer should use the thumb and the index finger to squeeze just the belly of the involved finger, and that every squeeze should be forceful, quick and instantaneous. It was suggested that if this method was properly performed it could improve the survival rate of replanted fingers. The mechanism of squeezing technique in the treatment of venous crisis following replantation of finger was proposed.

Animals↗
PubMed1996

Trials of 9-amino-20(S)-camptothecin in Boston.

9-Amino-20(S)-camptothecin (9-AC) is an analog of camptothecin with limited water solubility which has shown significant preclinical activity in a variety of human solid tumor xenografts. A Phase I trial using a soluble formulation of 9-AC, given as a 72-hour continuous infusion, has been completed. Thirty-one patients with resistant cancers received 5-60 micrograms/M2/h at three week intervals. The Maximum Tolerated Dose (MTD) was 45 micrograms/M2/hour. Neutropenia was the dose limiting toxicity, with few significant non-myelosuppressive toxicities. Minor responses were seen in 3/31 patients. Pharmacokinetic studies of 9-AC lactone (closed ring) showed substantial interpatient variability with a predicted half-life of 36 hours. A phase I/II trial of the same formulation of 9-AC is ongoing in refractory leukemia. Stomatitis and diarrhea are the non-myelosuppressive dose limiting toxicities. Evidence of antineoplastic activity has been seen in 3/15 patients. A Phase II trial in previously untreated metastatic breast cancer is also underway. A Phase I trial of a colloidal dispersion formulation, not yet completed, is better tolerated with a MTD > 45 micrograms/M2/h as a 72-hour continuous infusion. Evidence of antineoplastic activity has also been demonstrated.

Adult↗
PubMed1996

The chicken malic enzyme gene: structural organization and identification of triiodothyronine response elements in the 5'-flanking DNA.

In vivo, feeding stimulates and starvation inhibits transcription of the malic enzyme gene. In chick-embryo hepatocytes in culture, triiodothyronine (T3) stimulates and glucagon inhibits transcription of this gene. As a first step in the characterization of the involved regulatory mechanisms, fragments of genomic DNA spanning the structural and 5'-flanking regions of the chicken malic enzyme gene were cloned. The coding region of the gene is organized into 14 exons and 13 introns and is greater than 106 kb in length. The size of the gene, the number and lengths of the exons, and positions at which introns are inserted into the coding regions are virtually identical in the chicken and rat genes. When transiently transfected into chick-embryo hepatocytes, 5800 bp of 5'-flanking DNA conferred T3 responsiveness to a linked chloramphenicol acetyltransferase (CAT) reporter gene. Using deletion and site-specific mutations of 5'-flanking DNA, we identified a complex T3 response unit that contains one major T3 response element (T3RE) and several minor ones. The major element contains two degenerate copies of the hexamer, RGGWMA, separated by 4 bp and was a strong repressor in the absence of ligand. Endogenous levels of T3 receptor are sufficient to allow the T3 response elements in the upstream region of the malic enzyme gene to confer responsiveness to T3, suggesting that they are physiologically relevant.

Animals↗
PubMed1996

Sulphatide binds to human and animal influenza A viruses, and inhibits the viral infection.

We found, by using a virus overlay assay, that influenza A virus isolates bind to sulphatide (HSO3-Gal beta 1-->1'Cer), which has no sialic acid residue, and that the infection of Madin-Darby canine kidney cells with the human influenza virus A/Memphis/1/71 (H3N2) is inhibited by sulphatide. A/Memphis/1/71 (H3N2) causes obvious haemagglutination and low-pH haemolysis of asialoerythrocytes reconstituted with sulphatide. All influenza A virus isolates from the species of animals so far tested bound to sulphatide. The sulphatide-binding specificity of the isolates was different from the viral sialyl-linkage specificity. Influenza A virus isolates also bound to galactosyl ceramide (GalCer; Gal beta 1-->1'Cer), as well as sulphatide, in the virus overlay assays. In contrast, the influenza virus did not bind to N-deacyl, a derivative of sulphatide, glucosyl ceramide or the other neutral glycolipids tested. These results indicate that the linkage of galactose, or sulphated galactose, to ceramide is important for viral binding.

Animals↗
PubMed1996

Insulin and secretagogues differentially regulate fluid-phase pinocytosis in insulin-secreting beta-cells.

The physiological role of the beta-cell insulin receptor is unknown. To evaluate a candidate function, the insulin regulation of fluid-phase pinocytosis was investigated in a clonal insulinoma cell line (beta TC6-F7) and, for comparison, also in Chinese hamster ovary cells transfected with the human insulin receptor (CHO-T cells). In CHO-T cells, the net rate of fluid-phase pinocytosis was rapidly increased 3-4-fold over the basal rate by 100 nM insulin, with half-maximal stimulation at 2 nM insulin, as assayed by cellular uptake of horseradish peroxidase from the medium. Wortmannin, an inhibitor of phosphatidylinositol (PI)-3-kinase, blocked insulin-stimulated pinocytosis with an IC50 of 7.5 nM without affecting the basal rate of pinocytosis. In insulin-secreting beta TC6-F7 cells, the secretagogues glucose and carbachol (at maximally effective concentrations of 15 mM and 0.5 mM respectively) augmented fluid-phase pinocytosis 1.65-fold over the basal rate. Wortmannin also inhibited secretagogue-stimulated pinocytosis in these beta-cells with an IC50 of 7 nM but did not affect the basal rate of pinocytosis measured in the absence of secretagogues. Wortmannin did not influence either basal or secretagogue-induced insulin secretion. Although these beta TC6-F7 cells have cell-surface insulin receptors, adding exogenous insulin or insulin-like growth factor 1 did not affect their rate of fluid-phase pinocytosis, either in the absence or presence of secretagogues. From these observations, we conclude that: (1) in both insulin-secreting beta-cells and in conventional, insulin-responsive CHO-T cells, a common, wortmannin-sensitive reaction, which probably involves PI-3-kinase, regulates fluid-phase pinocytosis; (2) the insulin-receptor signal transduction pathway is dissociated from the regulation of fluid-phase pinocytosis in the insulin-secreting beta-cell line we studied; and (3) the enhancement of fluid-phase pinocytosis associated with secretagogue-induced insulin release in beta TC6-F7 cells is not attributable to autocrine activation of beta-cell surface insulin receptors.

Androstadienes↗
PubMed1996

A novel strain, B/Gifu/2/73, differs from other influenza B viruses in the receptor binding specificities toward sialo-sugar chain linkage.

We reported in a previous paper (1. Xu et al, J. Biochem., 115, 202-207, 1994) that every human influenza B virus isolate determined, including B/Lee/40, B/Setagaya/3/56, B/Tokyo/7/66, B/Kagoshima/1/68, B/Kanagawa/3/76, B/Ibaraki/2/85, B/Yamagata/16/88, and B/Bangkok/163/90, restrictively recognizes lacto-series gangliosides containing Neu5Ac alpha 2-6Gal linkage. We found in this study a novel strain, B/Gifu/2/73, that showed remarkable receptor binding specificities to both Neu5Ac alpha 2-3 Gal and Neu5Ac alpha 2-6Gal linkages of lacto-series gangliosides. The amino acid sequence of the hemagglutinin (HA) in strain B/Gifu/2/73 was compared with that of B/Lee/40, B/Ibaraki/2/85, B/Yamagata/16/88, and B/Bangkok/163/90. Substitution of His116, Ala121, Arg141, Pro211, His253, and His271 in the HA1 subunit of strain B/Gifu/2/73 for Asn116, Thr121, Gly141, Gln211, Gln253, and Gln271 in the HA1 of the four strains above was found, indicating that these amino acid changes in the HA1 of B/Gifu/2/73 may play an important role in recognition of Neu5Ac alpha 2-3Gal and Neu5Ac alpha 2-6Gal linkages in the receptor sialo-sugar chains.

Amino Acid Sequence↗
PubMed1996

Characterization of a polypyrimidine/polypurine tract in the promoter of the gene for chicken malic enzyme.

Starvation inhibits and refeeding stimulates transcription of the malic enzyme gene in chick liver. DNA between -320 and +72 base pairs (bp) is DNase I-hypersensitive in hepatic nuclei from fed but not starved chicks (Ma, X. J., and Goodridge, A. G. (1992) Nucleic Acids Res. 20, 4997-5002). A polypyrimidine/polypurine (PPY/PPU) tract lies within the DNase I-hypersensitive region. In hepatocytes transiently transfected with plasmids containing triiodothyronine response elements and a minimal promoter from the malic enzyme gene linked to the chloramphenicol acetyltransferase gene, deletion of the PPY/PPU tract inhibited chloramphenicol acetyltransferase activity by about 90% with or without triiodothyronine. Fine mapping of S1 nuclease-sensitive sites suggests that the PPY/PPU tract can assume different isoforms of non-B-DNA, some of which may be triplex structures. The PPY/PPU tract contains specific binding sites for single- and double-stranded DNA binding proteins and, with 8 bp 3' of the tract, can function as a promoter. A (CT)7 repeat binds single-stranded DNA-binding protein and is essential for promoter activity. Two C-rich elements bind single-stranded DNA-binding proteins and may mediate inhibition of promoter function. The single- and double-stranded DNA-binding proteins that interact with the PPY/PPU tract may regulate transcription of the malic enzyme gene.

Animals↗
PubMed1996

The XPB and XPD DNA helicases are components of the p53-mediated apoptosis pathway.

The molecular pathway of p53-dependent apoptosis (programmed cell death) is poorly understood. Because p53 binds to the basal transcription-repair complex TFIIH and modulates its DNA helicase activities, we hypothesized that TFIIH DNA helicases XPB and XPD are members of the p53-mediated apoptotic pathway. Whereas transfer of a wild-type p53 expression vector by microinjection or retroviral infection into primary normal human fibroblasts resulted in apoptosis, primary fibroblasts from individuals with xeroderma pigmentosum (XP), who are deficient in DNA repair and have germ-line mutations in the XPB or XPD gene, but not in the XPA or XPC gene, have a deficiency in the apoptotic response. This deficiency can be rescued by transferring the wild-type XPB or XPD gene into the corresponding mutant cells. XP-D lymphocytes also have a decreased apoptotic response to DNA damage by adriamycin, indicating a physiologically relevant deficiency. The XP-B or XP-D mutant cells undergo a normal apoptotic response when microinjected with the Ich-L, and ICE genes. Analyses of p53 mutants and the effects of microinjected anti-p53 antibody, Pab421, indicate that the carboxyl terminus of p53 may be required for apoptosis. Direct microinjection of the p53 carboxy-terminal-derived peptide (amino acid residues 319-393) resulted in apoptosis of primary normal human fibroblasts. These results disclose a novel pathway of p53-induced apoptosis.

Apoptosis↗
PubMed1996

Crystallization and preliminary X-ray diffraction studies of recombinant staphylokinase.

Staphylokinase, a fibrin-specific plasminogen activator, was highly expressed in Escherichia coli and purified by ion-exchange and gel-filtration chromatography. The purified recombinant staphylokinase was fully active and readily crystallized against 1.2 M sodium citrate in 100 mM Tris-HCl buffer at pH 8.0 using the hanging-drop method. Crystals of staphylokinase diffract to better than 2.2 A resolution. The crystal belongs to the tetragonal space group P4(1)2(1)2 or its enantiomorph with unit-cell parameters a = b = 67.5, c = 150.1 A. There are two molecules in the asymmetric unit. In this paper, we described the first crystallization of a kind of plasminogen activator and present the results of preliminary X-ray diffraction data from the native protein.

Journal Article↗