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Biomedical subjects

L Cheng

Publications and source records attributed to L Cheng.

At least 235 records · Page 13Linked to original sources
PubMed1998

Cognitive behaviour therapy approach to disputing automatic thoughts: a two-stage model.

Research shows that clients with automatic thoughts (dysfunctional thinking) often do not think of alternative explanations in relation to negative events. Furthermore, these automatic thoughts are characterized by a broad global, self-evaluative and ambiguous nature that could make disputing (or changing the ways they think) the most difficult part of the therapeutic process. This paper proposes a two-stage practise-based disputing model, guided by research, that aims to 'bring' an automatic thought to a specific, objective, quantifiable and concrete level at which not only is the particular aspect(s) of the automatic thought that causes emotional disturbances finely focused, but the disputing is also likely to be effective and manageable. Furthermore, it will also generate alternative explanations that are helpful in reducing emotional disturbances and in facilitating problem solving approach. In this paper, the authors use a case example to discuss the rationale that underpins the conceptualization of the model and to illustrate the process in which the strategies of the model are effectively used.

Cognitive Behavioral Therapy↗
PubMed1998

Cancer volume of lymph node metastasis predicts progression in prostate cancer.

Clinical outcome is variable in prostate cancer patients with regional lymph node metastasis. We studied 269 patients who had regional lymph node metastasis at the time of radical retropubic prostatectomy and bilateral pelvic lymphadenectomy at the Mayo Clinic between January 1987 and December 1992. Two hundred fifty-three (94%) patients received androgen deprivation therapy within 90 days of radical prostatectomy. Patients ranged in age from 47 to 79 years (median, 67 years). Median follow-up was 6.1 years (range, 0.3-10.5 years). Nodal cancer volume (size) was measured by the grid-counting method. Cox proportional hazards models were used to determine the impact of numerous clinical and pathologic findings on systemic progression-free survival. Systemic progression was defined as the presence of distant metastasis documented by biopsies or radiographic examinations (abdominal computerized tomography, plain radiographs, or bone scan). Five-year progression-free survival was 90%. In predicting systemic progression using Cox multivariate analysis, only nodal cancer volume added significantly to the model containing the primary cancer variables (Gleason score, cancer volume, and DNA ploidy). The relative hazard rate for a doubling in nodal cancer volume was 1.6 (95% confidence interval, 1.3 to 2.0; p < 0.0001). Spearman rank analysis showed a correlation between nodal cancer volume and Gleason score of the primary cancer, the number of positive nodes, the aggregate length of metastases, and the largest nodal cancer diameter (correlation efficient = 0.37, 0.63, 0.96, and 0.95, respectively). Our data indicate that nodal cancer volume was the most significant nodal determinant of progression to distant metastasis in lymph node-positive prostate cancer patients. We recommend that the diameter of the largest metastasis be evaluated in patients with metastases, because this is a more powerful predictor of patient outcome than current methods, which recommend mere counting of the number of positive nodes.

Aged↗
PubMed1998

Detection of tyrosinase mRNA in formalin-fixed, paraffin-embedded archival sections of melanoma, using the reverse transcriptase in situ polymerase chain reaction.

Most studies of the reverse transcriptase in situ polymerase chain reaction technique have reported results from assessments of cultured cells, frozen sections, and cytospin preparations. For application to routine diagnosis, it will be necessary to adapt the technique for use with formalin-fixed, paraffin-embedded tissues, the materials that are generally available. We have evaluated the feasibility of such an approach, using surgical pathology archival material from 25 UCLA patients: 15 tissues from primary and metastatic melanoma, 7 from nonmelanocytic tumors, including cancer of the lung, colon, kidney and skin and a thyroid adenoma, and 3 nontumorous tissues. Seven of 15 melanoma tissues gave a strong positive signal, 5 gave a weak signal, and 3 were negative. None of the 10 nonmelanoma tissues gave a positive signal. The specific reaction product was mainly located in the cytoplasm. None of the nonmelanocytic tumors or normal tissues demonstrated this pattern of cytoplasmic staining. Some nonspecific nuclear staining was observed in melanocytic and nonmelanocytic tumors and must not be overread as a true positive result. It is possible to detect tyrosinase mRNA in formalin-fixed, paraffin-embedded tissue sections of melanoma, but the technique remains too demanding for routine application.

Formaldehyde↗
PubMed1998

Primordial germ cells, stem cells and testicular cancer.

Primordial Germ Cells (PGCs) arise in the mouse embryo as a small population of cells some way from the gonad anlagen. In order for the embryo to develop into a fully fertile adult animal the PGCs must increase in number and reach the gonad. Mutations causing sterility in the mouse have identified some of the genes involved in regulating PGC development and some of these genes have been molecularly cloned. Similarly, mutations affecting the development and differentiation of PGC-derived tumors (teratomas and teratocarcinomas) have been identified in certain strains of mice and these identify genes involved in the normal growth and differentiation of PGCs. These studies should help to define the role of growth factors in PGC development and in the development of germ-cell-derived tumors.

Animals↗
PubMed1998

Cell cycle regulation of the Saccharomyces cerevisiae polo-like kinase cdc5p.

Progression through and completion of mitosis require the actions of the evolutionarily conserved Polo kinase. We have determined that the levels of Cdc5p, a Saccharomyces cerevisiae member of the Polo family of mitotic kinases, are cell cycle regulated. Cdc5p accumulates in the nuclei of G2/M-phase cells, and its levels decline dramatically as cells progress through anaphase and begin telophase. We report that Cdc5p levels are sensitive to mutations in key components of the anaphase-promoting complex (APC). We have determined that Cdc5p-associated kinase activity is restricted to G2/M and that this activity is posttranslationally regulated. These results further link the actions of the APC to the completion of mitosis and suggest possible roles for Cdc5p during progression through and completion of mitosis.

Anaphase-Promoting Complex-Cyclosome↗
PubMed1998

Learning from multiple perspectives: global implications for speech-language and hearing professionals.

The concept of cross-cultural communicative competence provides the framework for the discussion of global communication. A global communicator must be willing to continue to learn and embrace cultural and individual diversity. This paper presents new global realities as they exist in today's global 'village'. The three C's: concepts, competence, and connections are necessary in global communication and transactions. Local implications are discussed followed by identification of the necessary competences for global communicators.

Adult↗
PubMed1998

Analysis of repair and mutagenesis of chromium-induced DNA damage in yeast, mammalian cells, and transgenic mice.

Chromium (Cr) is a widespread environmental contaminant and a known human carcinogen. We have used shuttle vector systems in yeast, mammalian cells, and transgenic mice to characterize the mutational specificity and premutational DNA damage induced by Cr(VI) and its reduction intermediates in order to elucidate the mechanism by which Cr induces mutations. In the yeast system, treatment of vector-containing cells with Cr(VI) results in a dose-dependent increase in mutations in the SUP4-o target gene of the vector; mutagenesis is enhanced in an apn-1 yeast mutant, deficient in the capacity to repair oxidative-type DNA damage. In vector-containing mammalian cells, treatment with Cr(VI) also results in a dose-dependent increase in mutations in the vector target gene supF. The Cr-induced mutations in supF occurred mostly at G:C base pairs and were widely distributed across the gene, a pattern similar to those observed with ionizing radiation or hydrogen peroxide. These results support the hypothesis that Cr(VI)-induced oxidative-type DNA damage is responsible for Cr mutagenesis in the cell. Recently these studies were extended into the Big Blue transgenic mouse system in which Cr-induced mutagenesis was observed in the lung, the target organ for Cr carcinogenesis in humans. Analysis of the spectrum of these mutations will test whether Cr mutagenesis occurs by similar mechanisms in the intact animal as in cell culture systems and yeast.

Animals↗
PubMed1998

Anti-Sa antibody in Chinese rheumatoid arthritis.

OBJECTIVE: To test anti-Sa antibody in different autoimmune connective tissue diseases and analyze the relationship between Sa antibody and clinical manifestations and laboratory tests in rheumatoid arthritis. METHOD: Sa antigen was extracted from human placenta. Anti-Sa antibody was tested in 40 normal people and 478 connective tissue disease (CTD) patients using Western Blotting (WB). RESULTS: Sa antigen was a protein with molecular weights of 50 kD and 55 kD. Anti-Sa antibody was positive in 31.9% (61/191) rheumatoid arthritis (RA), 3.0% (2/67) Sjögren's syndrome (SS), 4.3% (2/46) systemic lupus erythmatosus (SLE) and 0% (0/66) Behcet's disease, 0% (0/60) polymyositis/dermatomyositis (PM/DM), 0% (0/66) other CTD and 0% (0/40) normal controls. Anti-Sa antibody was different from other auto-antibodies in RA. In rheumatoid arthritis its sensitivity, specificity, positive prediction rate, negative prediction rate were 31.9%, 98.6%, 93.8% and 68.5% respectively. Anti-Sa antibody positive patients were significantly different from anti-Sa antibody negative patients in moming stiffness, ESR, ANA and X-ray grade. CONCLUSION: Anti-Sa antibody was a new auto-antibody for the diagnosis of RA. Anti-Sa antibody positive patients seem to have more serious inflammation and more advanced disease process.

Adult↗
PubMed1998

[Study of a new type of material substituted for human hard tissues-hydroxyl poly calcium sodium phosphate: histologic report implants in mandible of animals].

This study was aimed to evaluate the histocompatibility of hydroxyl poly calcium sodium phosphate (HPPA) preliminarily. HPPA and hydroxylapatite were implanted in the mandibular defect in dogs. The implant-bone interface was observed by using stereomicroscope and decalcified histologic sections. The result demonstrates that HPPA has well-osseous integrated property after being implanted into bone tissues. This suggests that HPPA might be a new material of future excellence in substitution for human hard tissues.

Animals↗
PubMed1998

[Failure of mifepristone induced interruption of pregnancy: point mutation at genetic codon 722 in human progesterone receptor gene].

OBJECTIVE: To detect the point mutation of hormone binding domain (HBD) of human progesterone receptor (hPR) gene by molecular biological methods in women with insensitivity to mifepristone. METHODS: 26 women in 5 hospitals were consented in the study. 16 women were as study group: continuing pregnancy in 11 and missed abortion in 5. 10 women with successful abortion were as control group. Decidual tissue was collected in each woman and RNA was extracted from it and purified. Reverse transcription-polymerase chain reaction (RT-PCR), single strand conformation polymorphism(SSCP) and restriction enzyme reaction were performed. All women were followed up. RESULT: No point mutation of HBD of hPR gene was detected in control group except one with point mutation in trace. Point mutation of HBD of hPR gene was detected in 7 of women with continuing pregnancy. Mifepristone was administrated in midluteal phase in two of these women and no vaginal bleeding was observed. No mutation of hPR gene in the other women with continuing pregnancy. Three women had pregnancy again in 6 months and had successful abortion. The other one administrated mifepristion in midluteal phase and had second vaginal bleeding. No point mutation of hPR gene was detected in women with missed abortion. CONCLUSION: There is point mutation of HBD of hPR gene in women with insensitivity to mifepristone, and women with point mutation of hPR gene detected by molecular biological methods are really insensitive to mifepristone.

Abortifacient Agents, Steroidal↗
PubMed1998

[Verification of a new processing technology for pilot production of Aconitum coreanum (Lévl.) Raipaics].

The stability and feasibility of a new technology for processing Aconitum coreanum have been tested for pilot production by determining the components, toxicity(LD50) and traditional identification standard. The result shows that the contents of guanfu A and total alkaloid between the small trial and pilot production are slightly different and LD50 are nearly similar. Hypaconitine was not found in all kinds of processed products. The new technology has thus been proved stable and feasible.

Alkaloids↗
PubMed1998

[Research and application of far-infrared rays to drying Chinese medicinal herbs in small pieces].

OBJECTIVE: To introduce a far-infrared ray dryings device. METHOD: The research background, work tenets, structure, function, technical parameters and tentative application of the device were reported. Chinese medicinal herbs in small pieces which contain volatile oils were dried by far-infrared rays and airing. The two drying methods were compared. RESULT AND CONCLUSION: Not degrading the quality of medicinal herbs in small pieces, the device can be used to dry various kinds of medicinal herb pieces and thus deserves popularization.

Infrared Rays↗
PubMed1998

Global interaction, global inequality, and migration of the highly trained to the United States.

The authors "argue that national variation in the size of highly trained migration can be explained by interaction and inequality between nations, both reflecting the process of global integration. Guided by this analytical framework, we tested the structural determinants of highly skilled migration to the United States. The evidence confirms our hypotheses that economic and educational interactions between sending countries and the United States increase the flow of the highly trained to the United States. Results also provide mixed proof for our hypotheses that levels of professional migration are positively associated with disparities between sending countries and the United States in living conditions, research conditions, children's educational opportunities, political conditions, and professional employment opportunities."

Americas↗
PubMed1998

[Studies on the polysaccharide of Fomes marginatus].

This paper reports that polysaccharose was prepared by ethanol precipitation of water extracted and by deproteinization with sevage method, purification obtain Fomes marginatus. The polysaccharose which was determined by using sephadex-G, PAGE, ACTME, TLC and PC is single composition. [alpha]D20 = 28.89, it content of polysaccharose is 22.62 percent. It was hydrolied of periodate oxidation, smith degradation and IR analysis, the results show that the main chain is composed of B-(1-->4), (1-->6) linkage.

Chromatography, Paper↗
PubMed1998

[Simultaneous determination of zinc, cadmium and lead chelated by porphyrin with partial least squares fluorimetry].

The fluorescence spectra of super-highly sensitive chelate systems containing multicomponent metal porphyrins are analysed by partial least squares method, and a computerized analysis for the simultaneous determination of zinc, cadmium and lead is developed. Zinc, cadmium and lead can quantitatively combine with meso-tetrakis-(4-methoxyphenyl)-porphyrin in a strong base medium and in the presence of Tween-80 when they are heated for 30 min in a boiling water-bath. The proposed method has been applied to the simultane ous determination of zinc, cadmium and lead in artificial and environmental water samples, and the recovery ratios are in the range of 93.2-107%.

English Abstract↗
PubMed1998

Reduced expression of hMLH1 and hGTBP/hMSH6: a risk factor for head and neck cancer.

Head and neck cancer, like lung cancer, is considered a paradigm of an environmentally induced disease. Genetically determined variation in DNA repair capacity is thought to contribute to susceptibility to tobacco-related cancers. In this molecular epidemiology study, we investigated the association between DNA mismatch-repair (MMR) gene expression and the risk of head and neck cancer. Using our newly developed multiplex reverse transcription-PCR assay, we simultaneously evaluated the relative expression levels of five MMR genes (hMSH2, hMLH1, hPMS1, hPMS2, and hGTBP/hMSH6) in the peripheral blood lymphocytes of 78 patients (mean age = 59.6 +/- 12.4 years) with newly diagnosed head and neck cancer and 86 healthy controls (mean age = 58.2 +/- 12.9 years). The relative MMR gene expression was not correlated with disease stage or tumor site in the cases or with smoking and alcohol use in the controls. The expression levels increased with age in both cases and controls, but the mean expression of hMLH1, hPMS1, and hGTBP/hMSH6 was significantly lower in the cases than in the controls (P < 0.05). Using the median expression level in controls as the cutoff value, significantly increased odds ratios (ORs) were associated only with low expression of hMLH1 (OR = 4.4; 95% confidence interval = 2.1-9.1) and hGTBP/hMSH6 (OR = 2.1; 95% confidence interval = 1.1-4.1) after adjustment for age, sex, ethnicity, smoking status, and alcohol use. The results suggest that low hMLH1 and hGTBP/hMSH6 expression is associated with an increased risk of head and neck cancer. Additional studies with a larger number of subjects are warranted to confirm these findings.

Adaptor Proteins, Signal Transducing↗
PubMed1998

Expression of p27kip1 in prostatic adenocarcinoma.

p27kip1 (p27) protein is an inhibitor of cyclin and cyclin-dependent kinase complexes and prevents progression of cells from G1 to the S phase of the cell cycle. p27 might have tumor suppressor activity, and decreased p27 expression is associated with aggressive tumor behavior in several human malignancies. The object of this study was to evaluate p27 expression in prostatic adenocarcinoma treated by radical prostatectomy and to assess its association with numerous morphologic and clinical features. One hundred thirty-eight prostatic adenocarcinomas were evaluated for p27 expression by quantifying nuclear immunohistochemical staining. p27 expression was tested for association with patient age, family history of prostate cancer, preoperative serum prostate-specific antigen level, Gleason score, extraprostatic extension, seminal vesicle involvement, lymph node metastases, tumor-node-metastasis stage, DNA ploidy by flow cytometric analysis, and subclinical biochemical failure. p27 expression was analyzed as a continuous variable, and we also classified the tumors as low expressors (< 50% of cells p27 positive) or high expressors (> 50% of cells p27 positive) for comparison. Patients with adenocarcinomas that exhibited low p27 expression had higher mean Gleason scores than did high expressors (7 vs. 6.2, respectively; P = .002). Low p27 expression correlated with positive surgical margins (P = .05), seminal vesicle involvement (P = .007), lymph node metastasis (P = .03), and aneuploid cancers (P = .003), but it did not correlate with subclinical biochemical failure. p27 expression correlated with a number of prognostic morphologic features in prostatic adenocarcinoma, and the evaluation of p27 expression might provide additional prognostic information.

Adenocarcinoma↗