[Progresses in otorhinolaryngology in China, 1995].
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Animals↗
Biomedical subjects
C Liu
Publications and source records attributed to C Liu.
[Cloning of a cluster of genes encoding coli-surface antigen 6(CS6) of human enterotoxigenic E. coli].
A gene library was constructed from large plasmid DNA of wild strain E519/66A of human enterotoxigenic Escherichia coli (ETEC). Positive colonies containing CS6 antigen were obtained. The CS6 gene fragment was identified by restriction endonuclease mapping. It was approximately 4.6 kb in length and responsible for encoding CS6 genes and regulating the CS6 antigen. Two forms of fimbriae protein with different molecular weight were produced by the selected clones. Both of them could react with the same CS6 antiserum. So we expect to use the recombinant strain as candidate for human ETEC vaccine development, and it is also useful for further research on the expression and regulation of genes encoding CS6 fimbriae protein.
Antigens, Bacterial↗
[A quantitative study on nuclear DNA content and morphological parameters in ovarian cystadenocarcinoma].
OBJECTIVE: To study nuclear DNA content and morphological parameters in ovarian cystadenocarcinoma. METHODS: Nuclear DNA content and morphological parameters were quantitatively determined by image analysis technology in 56 cases of ovarian cystadenocarcinoma, 12 benign ovarian cystadenoma and 10 normal ovarian epithelial tissue. RESULTS: DNA content of ovarian cystadenocarcinoma was the highest among the three groups; and there were significant differences between the groups (P < 0.01). In the aspect of morphometry, nuclear circle was greatly different among the three groups (P < 0.01). There was no significant variances in nuclear parameter and area (P > 0.05). Nuclear DNA content of ovarian cystadenocarcinoma was related to its histopathological classification, histological grade and clinical stages (P < 0.01, P < 0.05). There was a reverse relationship between the DNA ploidy level and clinical prognosis. The 2-year survival rate of ovarian cystadenocarcinoma with diploidy/near diploidy pattern was higher than that with aneuploid pattern (P < 0.01). CONCLUSIONS: Nuclear DNA content of ovarian cystadenocarcinoma is a useful marker in reflecting the biological behavior and is of practical value in diagnosis, the choice of treatment methods and in the evaluation of results and prognosis.
Adolescent↗
Ultrastructure of parietal cells before and after extended parietal cell vagotomy in patients with duodenal ulcer and their complications.
Since 1979 we have treated 149 patients with duodenal ulcer by extended parietal cell vagotomy (EPCV). Electron microscopy of parietal cells from gastric body mucosa and gastric acid secretory test were carried out in 22 randomly selected patients before and after EPCV. It was shown that before EPCV the ultrastructure of parietal cells presented the feature of vigorous section identical to the hyperfunctional secretion of gastric acid. The ultrastructure of parietal cells presented the feature of acute depression of secretory function, which was identical to a significant reduction of secretory function of gastric acid 0.5-6 months after EPCV. Two to 10 years after operation, however, especially over 10 years after EPCV, the ultrastructural changes of parietal cells gradually returned to normal, but gastric acid secretion remained at a low level, without preoperative secretory capacities. The results of this study provide a histological basis for the application of extended parietal cell vagotomy in the treatment of duodenal ulcer and its complications.
Adult↗
Preparation and characterization of monoclonal antibodies against aflatoxin B1.
Five hybridoma cell lines producing monoclonal antibodies (MAb) against Aflatoxin B1 (AFB1) were established after fusion of mouse myeloma cells (SP-2/O-Ag-14) with spleen cells isolated from male BALB/c mice immunized with AFB1-BSA conjugate. Among these, one MAb, designated AFB1-2H8, was of the subtype IgG3 and the acidic fluid of which gave high dilution titers (1:5 x 10(5). The sensitivity of a competitive inhibition enzyme immunoassay (CIEIA) using AFB1-2H8 for AFB1 demonstrated that the linear range was 0.5-50 ng/ml and the minimum detectable concentration of AFB1 was 0.01 ng/ml. The specificity of the MAb was determined and showed no significant crossreaction with any of the metabolites tested. So th-- MAb and the CIEIA described may be useful in the detection of AFB1 in food and feed.
Aflatoxin B1↗
[Acute cholangitis due to bile duct stones: clinical analysis of 85 cases].
A retrospective review of 85 patients with acute calculous cholangitis who underwent emergency surgery (n = 85) was carried out. There were 28 men and 57 women and their mean age was 61.4 years. All patients had abdominal pain, 81% had chills and fever, 75% had clinical jaundice, and 28.2% were in shock. There were 48 severe acute cholangitis (group 1) and 37 acute cholangitis (group 2). The incidence of a positive bile culture in group 1 was 100% (28/28) and that of group 2 was 85% (17/20). The morbidity and mortality in group 1 was 43.8% and 20.8%, respectively. Five patients (13.5%) in group 2 had simple wound infection, and there was no severe complications or death. A significantly lower platelet count was documented in group 1 (86.5 +/- 40.7 x 10(9)/L) as compared with group 2 (159.9 +/- 63.9 x 10(9)/L) (P < 0.001). It is suggest that platelet count less than 90 x 10(9)/L at the time of admission or preoperation may serve as a guideline for identifying high-risk patient in early surgical intervention.
Acute Disease↗
Human high molecular weight-melanoma associated antigen mimicry by mouse anti-idiotypic monoclonal antibody MK2-23: modulation of the immunogenicity in patients with malignant melanoma.
The mouse anti-idiotypic (anti-id) mAb MK2-23 bears the mirror image of the antigenic determinant defined by antihuman high molecular weight-melanoma associated antigen (HMW-MAA) mAb 763.74. The purpose of this study was to evaluate the effect of conjugation to a carrier and administration with an adjuvant and cyclophosphamide (CTX) on the immunogenicity of anti-id mAb MK2-23 in patients with malignant melanoma and to analyze the relationship between development of humoral immunity and survival time of patients. Fifty-eight patients were sequentially entered into four immunization protocols which included administration of mAb MK2-23, mAb MK2-23 conjugated to keyhole limpet hemocyanin (KLH) and mixed with Bacillus Calmette-Guérin (BCG), mAb MK2-23 and CTX, and mAb MK2-23 conjugated to KLH and mixed with BCG and CTX. Six patients could not be evaluated since they withdrew from the clinical trial after the first immunization. Sera were tested for the development of anti-anti-id antibodies, including those reacting with HMW-MAA. Testing of sera for development of antimouse Ig antibodies was used to monitor the immune competence of patients. Conjugation to KLH and administration with BCG markedly enhanced the ability of mAb MK2-23 to induce anti-anti-id antibodies, including those reacting with HMW-MAA. In contrast, pretreatment with CTX had no detectable effect on the ability of mAb MK2-23 to elicit a humoral anti-anti-id response. Kaplan-Meier survival analysis showed that the performance status of patients, anti-anti-id antibody level, and development of anti-HMW-MAA antibodies had an effect on survival time. This effect was found when the survival time was calculated both from the day of the first immunization and from 4 weeks after the first immunization to the end of the study. A multivariate analysis by Cox regression showed that the development of anti-HMW-MAA antibodies was the most important variable for predicting survival, and that performance status was the only variable that significantly added to the prediction of survival. These data have to be interpreted with caution because of the retrospective nature of the analysis. Nevertheless, the present study suggests that mAb MK2-23 represents a useful immunogen to implement active, specific immunotherapy in patients with malignant melanoma.
Animals↗
Regulation of pyrBI operon expression in Escherichia coli by UTP-sensitive reiterative RNA synthesis during transcriptional initiation.
Pyrimidine-mediated regulation of pyrBI operon expression in Escherichia coli K-12 occurs through UTP-sensitive transcriptional attenuation and through a second mechanism that functions at the level of transcriptional initiation. In this study we demonstrate that this second control mechanism is based on UTP-sensitive reiterative RNA synthesis within a run of three T-A base pairs in the pyrBI initially transcribed region. Our results show that high UTP levels induce the synthesis in vitro of nascent transcripts with the sequence AAUUUUn (where n = 1 to > 30), which are not extended downstream to include pyrBI sequences. Synthesis of these transcripts, which are initiated at the predominant in vivo transcriptional start site, inhibits the production of full-length pyrBI transcripts. A TTT to GTA mutation in the pyrBI initially transcribed region eliminates reiterative transcription and stimulates productive transcription in vitro. When introduced into the E. coli chromosome, this mutation causes a sevenfold increase in pyrBI expression in cells grown under conditions of pyrimidine excess and nearly abolishes pyrimidine-mediated regulation of pyrBI expression when coupled with a mutation that eliminates attenuation control. Additional experiments indicate that the context of the three T-A base pairs within the pyrBI initially transcribed region is important for reiterative transcription. A possible mechanism for reiterative transcription and the likely involvement of this process in the regulation of other genes are discussed.
Base Composition↗
Structural determination of the Si(111) sqrt 3 x sqrt 3-Bi surface by x-ray standing waves and scanning tunneling microscopy.
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Journal Article↗
Vub extraction from exclusive decays.
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Journal Article↗
Design of potent and selective inhibitors of myo-inositol 1,4,5-trisphosphate 5-phosphatase.
The interactions of synthetic analogues of D-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] with the Ins(1,4,5)P3 receptor in permeabilized SH-SY5Y cells and with two key metabolic enzymes, Ins(1,4,5)P(3)3-kinase from a supernatant preparation of rat brain homogenates and Ins(1,4,5)P(3)5-phosphatase from human erythrocyte ghosts, have been examined. L-chiro-Inositol 2,3,5-trisphosphorothioate [L-chiro-Ins(2,3,5)PS3], which we have previously identified as a partial agonist at the Ins(1,4,5)P3 receptor [Safrany, S. T., Wilcox, R. A., Liu, C., Dubreuil, D., Potter, B. V. L., & Nahorski S. R. (1993) Mol. Pharmacol. 43, 499-503], is identified as the most potent 5-phosphatase inhibitor yet described (inhibiting dephosphorylation of [3H]Ins(1,4,5)P3 with Ki = 230nM). L-chiro-Ins(2,3,5)PS3 was also found to be the most potent small-molecule inhibitor of 3-kinase (Ki = 820 nM). The properties of three novel, potent, and selective inhibitors of 5-phosphatase are described. L-myo-Inositol 1,4,5-trisphosphorothioate inhibited 5-phosphatase with Ki = 430 nM, showing 250-fold selectivity over 3-kinase (Ki = 108 microM); myo-inositol 1,3,5-trisphosphorothioate inhibited 5-phosphatase with 475-fold selectivity over 3-kinase (Ki = 520 nM and 247 microM, respectively). The most potent, selective inhibitor of 5-phosphatase was L-chiro-inositol 1,4,6-trisphosphorothioate [L-chiro-Ins(1,4,6)PS3]. L-chiro-Ins(1,4,6)PS3 inhibited 5-phosphatase with Ki = 300 nM and did not interact with the Ins(1,4,5)P3 receptor or 3-kinase at doses tested. These studies, therefore, identify a highly potent and selective inhibitor of 5-phosphatase, which should be considered the tool of choice when inhibiting this enzyme in a broken cell or cell-free system.
Animals↗
A study on superoxide dismutase activity of some model compounds.
The synthesis and characteristics of a binuclear ligand N,N,N',N'-tetrakis (2'-benzimidazolyl methyl)-1,4-diethylene amino glycol ether (EGTB) and its series of coordination compounds containing copper(II), iron(III), and manganese(II) with and without exogenous bridging ligand which was imidazolate ion (Im-), bipyridine (bpy), or 1,10-phenanthroline (phen) are reported. Depending on the redox potentials by cyclic voltammetry, the coordination compounds can act as catalysts for the dismutation of superoxide radicals (O2-). The detection of the rate constant of the reaction of superoxide ion with nitroblue tetrazolium (NBT) which is inhibited by superoxide dismutase (SOD) and its model compounds of the EGTB system has been performed by a modified illumination method. The rate constants kQ of the catalytic dismutation have been obtained.
Copper↗
The energetic linkage of GTP hydrolysis and the synthesis of activated sulfate.
ATP sulfurylase, from Escherichia coli K-12, catalyzes both the hydrolysis of GTP and the synthesis of activated sulfate (APS). This paper describes the energetic linkage of these reactions and the events that couple them. Steady-state and single-turnover experiments suggest that the binding of GTP inhibits APS production and that the hydrolysis of GTP is required to generate the enzyme form(s) that produces APS. It is this progression from the inhibitory, E-GTP, to the productive, E-GDP, complexes in the cycle of APS synthesis that energetically links these two reactions. This model stands in contrast to other GTPase/target systems in which the binding of GTP alone is sufficient to catalyze multiple turnovers of the target reaction. The stoichiometry of GTP hydrolysis to APS synthesis is 1:1, and equilibrium measurements show that -9.1 kcal/mol, produced by the hydrolysis of GTP, is used to thermodynamically drive production of APS and PPi. These findings establish the mechanism of energy transfer in this novel GTPase/target system, and substantially alter our understanding of the energetics of sulfate activation, an essential step in the metabolic assimilation of sulfur.
Catalysis↗
Calcium release activity and metabolism of inositol 1,4,5-trisphosphate in T cells. Modulation by novel inositol 1,4,5-trisphosphate 5-phosphatase inhibitors.
Stimulation of the T cell antigen receptor/CD3 complex is followed by phospholipase C activation, phosphoinositol lipid metabolism and ultimately by a rapid rise in both myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] and myo-inositol 1,3,4,5-tetrakisphosphate [Ins(1,3,4,5)P4] as well as cytosolic free calcium concentration. A 5-phosphatase plays a pivotal role in the subsequent metabolism of Ins(1,4,5)P3 and Ins(1,3,4,5)P4. Synthetic routes have been developed which have enabled the synthesis of both natural and unnatural inositol phosphates and this approach has yielded several compounds which have been shown to act as inhibitors of Ins(1,4,5)P3 5-phosphatase. These compounds offer considerable potential for investigation of the complex metabolism and function of Ins(1,4,5)P3 and Ins(1,3,4,5)P4 in T cell activation and proliferation. We now report the time course and temperature sensitivity of Ins(1,4,5)P3-induced 45Ca2+ release in the permeabilised leukaemic T cell line Jurkat. Furthermore, we demonstrate that the metabolism of Ins(1,4,5)P3 in the presence of two novel 5-phosphatase inhibitors, namely L-myo-inositol 1,4,5-trisphosphorothioate [L-Ins(1,4,5)PS3] and myo-inositol 1,3,5-trisphosphorothioate [Ins(1,3,5)PS3], can be inhibited with concomitant elevation of the heparin-sensitive Ins(1,4,5)P3-induced release of 45Ca2+. These novel 5-phosphatase inhibitors provide a starting point for development of cell-permeable analogues which may be able to modulate cell function in intact cells and may be used as manipulative tools with which to elucidate the function of Ins(1,4,5)P3 and Ins(1,3,4,5)P4 with respect to T cell activation.
Animals↗
Growth and coalescence in submonolayer homoepitaxy on Cu(100) studied with high-resolution low-energy electron diffraction.
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Journal Article↗
Kinetic analysis of novel inhibitors of inositol polyphosphate metabolism.
The ability of the novel D-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P 3] analogues, L-chiro-inositol 1,4,6-trisphosphate [L-chr Ins(1,4,6)P3] and the corresponding trisphosphorothioate compound [L-chr Ins(1,4,6)PS3] to inhibit soluble inositol (1,4,5)P3/(1,3,4,5)P4-polyphosphate 5-phosphatase, potently and selectively, has been investigated. L-chr Ins(1,4,6)P3 competitively inhibited 5-phosphate specific dephosphorylation of Ins(1,4,5)P3 and inositol 1,3,4,5-tetrakisphosphate [Ins(1,3,4,5)P4] with apparent Ki values of 6.35 and 1.76 microM, respectively. L-chr Ins(1,4,6)PS3 competitively inhibited hydrolysis of Ins(1,4,5)P3 and noncompetitively inhibited dephosphorylation of Ins(1,3,4,5)P4 with apparent Ki values of 0.67 and 0.44 microM, respectively. L-chr Ins(1,4,6)PS3 did not affect Ins(1,4,5)P3 3-kinase activity. In the present investigation L-chr Ins(1,4,6)P3 and L-chr Ins(1,4,6)PS3 have been shown to be the most potent and selective inhibitors of inositol polyphosphate metabolism yet described.
Animals↗
Functional expression of rat peroxisomal acyl-CoA oxidase in Spodoptera frugiperda cells.
A cDNA coding the 661-residue rat peroxisomal fatty acyl-CoA oxidase (ACOX) has been constructed and expressed as catalytically active protein in Spodoptera frugiperda (Sf9) insect cells using baculovirus expression system. Recombinant viral clones were purified and the expressed protein was identified by immunoblotting and catalytic activity. In the rat liver, ACOX consists of three polypeptide components A, B and C, with relative molecular mass of 72 kDa, 51 kDa and 21 kDa, respectively. In Sf9 insect cells infected with the recombinant virus, ACOX protein (component A) was expressed up to 15% of the total cellular protein. Immunoblot analysis demonstrated that besides component A, components B and C were also present in Sf9 cells, suggesting that these components are derived from component A by post-translational proteolytic cleavage. However, unlike in rat liver, baculovirus generated ACOX in insect cells had reduced amounts of components B and C with an estimated molar ratio of A, B, C of 5:1:1 in Sf9 cells vs 1:5:5 in rat liver. By immunofluorescence and immunocytochemical methods the overexpressed recombinant ACOX was identified both in the cytoplasm and the nucleus of Sf9 cells. Polyclonal antibodies raised against recombinant ACOX recognized rat liver ACOX on immunoblotting. Baculovirus Sf9 system provides high-efficiency expression of functional ACOX and can be used to express specific mutant and truncated ACOX cDNAs for further characterization.
Acyl-CoA Oxidase↗
Synthesis of selective non-Ca(2+)-mobilizing inhibitors of D-myo-inositol 1,4,5-trisphosphate 5-phosphatase.
Syntheses of novel phosphorothioate-based non-Ca(2+)-releasing inhibitors of myo-inositol 1,4,5-trisphosphate 5-phosphatase are described. 1L-myo-Inositol 1,4,5-trisphosphorothioate, myo-inositol 1,3,5-trisphosphorothioate, and 1L-chiro-inositol 1,4,6-trisphosphorothioate have been synthesized from 1L-2,3,6-tri-O-benzyl-1-O-(cis-prop-1-enyl)-myo-inositol, 2,4,6-tris-O-(p-methoxybenzyl)-myo-inositol orthoformate and 1L-2,3,5-tri-O-benzyl-chiro-inositol, respectively. 1L-2,3,5-Tri-O-benzyl-chiro-inositol was also used to prepare 1L-chiro-inositol 1,4,6-trisphosphate. The phosphorothioates did not mobilize intracellular Ca2+ but were highly potent inhibitors of Ins(1,4,5)P3 5-phosphatase, and myo-inositol 1,3,5-trisphosphorothioate and 1L-chiro-inositol 1,4,6-trisphosphorothioate were selective for this enzyme.
Calcium↗