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M Tang

Publications and source records attributed to M Tang.

At least 73 records · Page 4Linked to original sources
PubMed1996

[A clinical study on the incidence of retroperitoneal lymph node metastasis and its risk factors in ovarian cancer].

OBJECTIVE: To investigate the incidence and the significant risk factors of retroperitoneal lymph node metastasis (LNM) in primary ovarian cancer for considering the necessity of systematic lymphadenectomy. METHODS: 117 cases of retroperitoneal lymphadenectomy performed on primary ovarian cancers in our hospital from November, 1987 to January, 1994 were studied. The relationship between clinicopathologic characters and the incidence of LNM were determined by univariate and multivariate analysis. RESULTS: In 44 (37.6%) of the 117 patients studied, LNM was confirmed pathologically. The chances of pelvic LNM (29.9%) were smilar to that of para-aortic LNM (20.9%) (P > 0.05). Univariate analysis showed that significantly increased incidence of LNM was clinically associated with bilateral involvement of the ovaries, presence of ascites, advanced stages, poor tumor differentiation, rather large residual tumors and some histopathological subtypes such as undifferentiated and serous adenocarcinoma. The size of the residual tumor, clinical stage and grade of differentiation were the most important risk factors for LNM (P < 0.05) by multivariate analysis. The indication, optimum time, the scope and model of systematic lymphadenectomy were evaluated and discussed. CONCLUSION: systematic lymphadenectomy was suggested only for early cases with high risk factors. For late cases with residual tumor the operation may be done at a chosen time, for instance, at second cytoreductive or second-look surgery.

Adenocarcinoma↗
PubMed1995

The LAR/PTP delta/PTP sigma subfamily of transmembrane protein-tyrosine-phosphatases: multiple human LAR, PTP delta, and PTP sigma isoforms are expressed in a tissue-specific manner and associate with the LAR-interacting protein LIP.1.

The transmembrane protein-tyrosine-phosphatases (PTPases) LAR, PTP delta, and PTP sigma each contain two intracellular PTPase domains and an extracellular region consisting of Ig-like and fibronectin type III-like domains. We describe the cloning and characterization of human PTP sigma (HPTP sigma) and compare the structure, alternative splicing, tissue distribution, and PTPase activity of LAR, HPTP delta, and HPTP sigma, as well their ability to associate with the intracellular coiled-coil LAR-interacting protein LIP.1. Overall, these three PTPases are structurally very similar, sharing 64% amino acid identity. Multiple isoforms of LAR, HPTP delta, and HPTP sigma appear to be generated by tissue-specific alternative splicing of up to four mini-exon segments that encode peptides of 4-16 aa located in both the extracellular and intracellular regions. Alternative usage of these peptides varies depending on the tissue mRNA analyzed. Short isoforms of both HPTP sigma and HPTP delta were also detected that contain only four of the eight fibronectin type III-like domains. Northern blot analysis indicates that LAR and HPTP sigma are broadly distributed whereas HPTP delta expression is largely restricted to brain, as is the short HPTP sigma isoform containing only four fibronectin type III-like domains. LAR, HPTP delta, and HPTP sigma exhibit similar in vitro PTPase activities and all three interact with LIP.1, which has been postulated to recruit LAR to focal adhesions. Thus, these closely related PTPases may perform similar functions in various tissues.

Adaptor Proteins, Signal Transducing↗
PubMed1995

Yeast two-hybrid system demonstrates that estrogen receptor dimerization is ligand-dependent in vivo.

Previous studies using in vitro procedures have not clearly established whether the estrogen receptor (ER) acts as a monomer or dimer in the cell. We have used the yeast two-hybrid system as an in vivo approach to investigate the dimerization of the estrogen receptor in the absence and presence of estrogen and anti-estrogens. This system is independent of ER binding to the estrogen response element. Two vectors, expressing GAL4 DNA binding domain-human ER and GAL4 transactivation domain-human ER, were constructed. Control experiments showed that each fusion protein had a high affinity binding site for estradiol-17 beta and could transactivate an ERE-LacZ reporter gene in yeast similar to the wild type ER. The two fusion proteins, GAL4 DB-hER and GAL 4 TA-hER, were expressed in the yeast strain, PCY2, which carries a GAL1 promoter-lacZ reporter. ER dimerization was measured via reconstitution of GAL4 through interaction of the fusion proteins, which transactivates LacZ through the GAL1 promoter. When both ER fusion proteins were expressed, beta-galactosidase activity was estradiol-17 beta-inducible. Furthermore, we showed that both tamoxifen and ICI 182,780 also induced beta-galactosidase activity, albeit lower than that induced by estradiol-17 beta. These results strongly argue that ER dimerization is ligand-dependent and the dimer can be induced by estradiol-17 beta, tamoxifen, or ICI 182,780. We also treated the yeast containing the two fusion proteins with estradiol-17 beta and tamoxifen or ICI 182,780 simultaneously to determine the effects on ER dimerization. beta-Galactosidase activity was lower when the yeast was treated with a higher ratio of tamoxifen or ICI 182,780 to estrogen than estradiol-17 beta alone. Taken together, we conclude that ER dimerization is ligand (estradiol-17 beta, tamoxifen, or ICI 182, 780)-dependent, and we suggest that estradiol-17 beta-induced dimers are destabilized when estradiol-17 beta is used with tamoxifen or ICI 182,780 simultaneously.

Base Sequence↗
PubMed1995

Cholest-3,5-dien-7-one formation in peroxidized human plasma as an indicator of lipoprotein cholesterol peroxidation potential.

Lipoprotein peroxidation susceptibility is routinely evaluated using products of unsaturated fatty acids as markers (e.g., malonaldehyde). The significance and factors influencing peroxidation of cholesterol moiety of lipoproteins are relatively unknown due to lack of a reliable marker product which can be measured easily. Under the influence of Cu2+ ions, the major product of lipoprotein cholesterol peroxidation (isolated after saponification) was cholest-3-5-dien-7-one (CSD). Apart from gas-liquid chromatography, this compound lends itself for measurement by alternative methods. Due to lack of the 3 beta-hydroxyl group, CSD was separated from the rest of the oxysterols and cholesterol by passing through digitonin-coated silica-gel G and its concentration was determined by absorption at 283 nm. The recovery of CSD by this method exceeded by 87%. The formation of CSD was also sensitive to vitamin E and therefore could be used as an index of lipoprotein cholesterol susceptibility to peroxidation.

Cholestenones↗
PubMed1995

Effect of radiofrequency catheter ablation on calcium channel of ventricular myocytes.

Using whole-cell patch-clamp technique, the effect of radiofrequency catheter ablation (RFCA) on calcium current (Ica) of guinea pig ventricular myocytes was examined. The radiofrequency energy delivered was 20 W x 10 s. RF-CA decreased Ica apparently with the affected area reaching up to 1.2 cm from the ablation focus. In the meanwhile, the pathological lesion size resulted from RFCA was merely 0.41 +/- 0.11 cm. These findings indicate that RFCA, apart from causing tissue necrosis by heat, can affect myocyte membrane currents in a large area. This may explain why RFCA has a very high success rate with a small pathological lesion.

Animals↗
PubMed1995

Qualitative analysis of Kolmogorov-type models of predator-prey systems.

The qualitative behaviors of Kolmogorov-type models are investigated under assumptions that are consistent with models of predator-prey systems and biologically realistic. The main purpose of this paper is to prove the boundedness of solutions and to give criteria for the existence of limit cycles for the system. In the case that the positive equilibrium is locally asymptotically stable, an example shows that there could be more limit cycles. This example serves as a counterexample to the global stability criterion of Huang.

Animals↗
PubMed1995

Consistency of clinical diagnosis in a community-based longitudinal study of dementia and Alzheimer's disease.

We evaluated the consistency of the diagnosis of dementia in a multicultural, longitudinal community-based study of cognitive impairment and dementia. We diagnosed dementia using a fixed neuropsychological paradigm; the diagnosis also required historical evidence of functional impairment. In a sample of 656 subjects with at least one annual follow-up examination, dementia was confirmed at 1 year in 89% of the 304 subjects initially demented, and in 90% of the 136 subjects with the initial diagnosis of probable Alzheimer's disease (AD). The 34 initially demented subjects who failed to meet criteria for dementia at follow-up included 13 with an initial diagnosis of probable AD. All 34 still had evidence of cognitive impairment; this group was more likely to have a history of pulmonary disease, multiple medication use, or chronic alcohol use than other demented patients. Consistency of dementia diagnosis did not vary according to educational attainment or ethnic background. The use of a neuropsychological paradigm such as ours in large longitudinal studies of dementia may minimize interobserver diagnostic variability or diagnostic drift over time while contributing the benefits of a comprehensive cognitive evaluation to the diagnostic process.

Aged↗
PubMed1995

[Some biochemical indexes in white rabbit's blood affected by acute high intensity microwave].

Irradiation of white rabbits by 10, 50, 100 and 200 mW/cm2 microwave respectively can cause the disorder of protein metabolism, the abnormality of blood sugar, and the change of the activity of serum alpha-hydroxybutyrate dehydrogenase, lactate dehydrogenase, glutamic oxalacetic transaminase, glutamic pyruvic transaminase, acid phosphatase ect. These changes can be used as indexes in the evaluation of the effect of acute high intensity microwave exposure. The effect on the organism mainly depends on the intensity of exposure provided the dose of microwave remains the same.

Acid Phosphatase↗
PubMed1995

[Flow cytometry used to distinguish between complete and partial hydatidiform moles].

The nuclear ploidy of 14 placentas was determined by flow cytometry. All histologically classified complete moles (4 cases), hydropic villi (4 cases) and control placentas (3 cases) were diploid; whereas two of three histologically classified partial moles were triploid. The remaining case classified as partial mole was diploid, most likely a complete mole. It was concluded that DNA flow cytometric analysis offers an informative supplement to the histological interpretation of hydropic placentas.

DNA, Neoplasm↗
PubMed1994

Fibroblast growth factor receptor gene expression and immunoreactivity are elevated in human glioblastoma multiforme.

Glioblastomas were examined for abnormalities in fibroblast growth factor receptor (FGFR) expression by polymerase chain reaction and immunocytochemical analysis. Polymerase chain reaction analysis demonstrated that FGFR1 mRNA levels were significantly higher in glioblastomas than in normal brain adjacent to the tumor or in untransformed human brain. These results were consistent with immunocytochemical localization of FGFR1 protein in glioblastomas: glioblastoma cells exhibited intense FGFR1 immunoreactivity in frozen sections of tumor and low to undetectable FGFR1 immunoreactivity in adjacent normal brain or in normal white matter obtained from patients without neoplastic disease. Endothelial cells of capillaries and larger vessels within the tumor were devoid of FGFR1 immunoreactivity. All glioblastomas evaluated in the present study expressed FGFR1 mRNA and FGFR1 immunoreactivity. Examination of the FGFR1 gene by Southern blot analysis indicated that overexpression of FGFR1 mRNA in glioblastomas did not result from gene amplification. These results indicate that glioblastoma cells, in contrast to endothelial cells within the tumor, display increased levels of FGFR1. Therefore, FGFR1 signal transduction may be associated with increased autocrine growth activity of tumor cells and is probably not related to the increased endothelial cell proliferation associated with these tumors.

Base Sequence↗
PubMed1994

Cardiac blood flow studies in fetuses with haemoglobin Bart's disease.

Blood flow across the atrioventricular valves and outflow tracts was measured in 55 normal fetuses and 32 fetuses with haemoglobin (Hb) Bart's disease between 18 and 26 weeks of gestation. The mean velocities remained unchanged in both normal and affected fetuses over the gestations studied. The volume flow across both atrioventricular valves and outflow tracts increased as the gestation advanced in both normal and affected fetuses, but was significantly higher in affected than in normal fetuses. The same magnitude of increased flow was found in both hydropic and non-hydropic fetuses with Hb Bart's disease. These findings suggest that fetuses with severe and long-standing anaemia have a remarkable cardiac compensatory mechanism for the maintenance of tissue oxygenation. In response to anaemia and circulatory loading, the cardiac chambers and outflow tracts enlarge proportionately up to twice the normal values. Because of this response and the operation of the Frank-Starling mechanism, the heart is able to maintain a normal mean velocity of propulsion and the net output is increased to two to three times that in normal fetuses. Hydropic changes in these anaemic fetuses appear unrelated to cardiac failure as cardiac failure is not observed at the time that hydropic changes develop.

Blood Flow Velocity↗
PubMed1994

UBP5 encodes a putative yeast ubiquitin-specific protease that is related to the human Tre-2 oncogene product.

A gene from chromosome V of the yeast Saccharomyces cerevisiae has been cloned and sequenced. The deduced amino acid sequence encoded by this gene is similar to several ubiquitin-specific proteases from yeast, especially at the highly conserved domain. It is thus named UBP5. UBP5 is also closely related to the human Tre-2 and the mouse Unp oncogene products. This study adds a new member to the ubiquitin protease family and suggests that alteration of ubiquitin protease activity may result in cancer in mammals. However, disruption of the UBP5 gene in a haploid strain did not result in a noticeable phenotypic alteration.

Amino Acid Sequence↗
PubMed1994

Production and secretion of interferon-gamma (IFN-gamma) in children with atopic dermatitis.

IFN-gamma is known to be a major inhibitor of IgE synthesis in vitro. Recent studies demonstrating reduced production of IFN-gamma in children and adults with atopic dermatitis and elevated serum IgE suggest a similar role for this cytokine in vivo. The reasons for this reduced IFN-gamma production are not known. One possibility is that atopic individuals have a reduced population of cells producing IFN-gamma in vivo. Using a fluorescence-labelled antibody to detect intracellular IFN-gamma, the percentage of IFN-gamma-producing cells was determined in children with atopic dermatitis and in non-atopic controls. Children with atopic dermatitis had a greater percentage of IFN-gamma-producing cells in unstimulated cultures compared with controls, indicating in vivo activation of lymphocytes in the atopic group. This could reflect the significant degree of inflammation present in these children, or the presence of bacterial infection or colonization. Although secretion of IFN-gamma after stimulation with phorbol myristate acetate (PMA)/Ca was significantly lower in children with atopic dermatitis compared with controls, the percentage of IFN-gamma-producing cells in the stimulated cultures from this group was equivalent to controls. This demonstrates that the reduced ability of atopic children to secrete IFN-gamma in vitro does not relate to a lack of IFN-gamma-producing cells, but to a difference in the regulation of IFN-gamma production beyond the stage of signal transduction.

Adolescent↗