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Biomedical subjects

J Q Shi

Publications and source records attributed to J Q Shi.

14 recordsLinked to original sources
PubMed2001

Maximum likelihood estimation of two-level latent variable models with mixed continuous and polytomous data.

Two-level data with hierarchical structure and mixed continuous and polytomous data are very common in biomedical research. In this article, we propose a maximum likelihood approach for analyzing a latent variable model with these data. The maximum likelihood estimates are obtained by a Monte Carlo EM algorithm that involves the Gibbs sampler for approximating the E-step and the M-step and the bridge sampling for monitoring the convergence. The approach is illustrated by a two-level data set concerning the development and preliminary findings from an AIDS preventative intervention for Filipina commercial sex workers where the relationship between some latent quantities is investigated.

Acquired Immunodeficiency Syndrome↗
PubMed2001

A sensitivity analysis for publication bias in systematic reviews.

There is no simple method of correcting for publication bias in systematic reviews. We suggest a sensitivity analysis in which different patterns of selection bias can be tested against the fit to the funnel plot. Publication bias leads to lower values, and greater uncertainty, in treatment effect estimates. Two examples are discussed. An appendix lists the S-plus code needed for carrying out the analysis.

Antibiotic Prophylaxis↗
PubMed2000

Reanalysis of epidemiological evidence on lung cancer and passive smoking.

OBJECTIVE: To assess the epidemiological evidence for an increase in the risk of lung cancer resulting from exposure to environmental tobacco smoke. DESIGN: Reanalysis of 37 published epidemiological studies previously included in a meta-analysis allowing for the possibility of publication bias. MAIN OUTCOME MEASURE: Relative risk of lung cancer among female lifelong non-smokers, according to whether her partner was a current smoker or a lifelong non-smoker. RESULTS: If it is assumed that all studies that have ever been carried out are included, or that those selected for review are truly representative of all such studies, then the estimated excess risk of lung cancer is 24%, as previously reported (95% confidence interval 13% to 36%, P<0.001). However, a significant correlation between study outcome and study size suggests the presence of publication bias. Adjustment for such bias implies that the risk has been overestimated. For example, if only 60% of studies have been included, the estimate of excess risk falls from 24% to 15%. CONCLUSION: A modest degree of publication bias leads to a substantial reduction in the relative risk and to a weaker level of significance, suggesting that the published estimate of the increased risk of lung cancer associated with environmental tobacco smoke needs to be interpreted with caution.

Female↗
PubMed2000

Meta-analysis, funnel plots and sensitivity analysis.

Publication bias is a major problem, perhaps the major problem, in meta-analysis (or systematic reviews). Small studies are more likely to be published if their results are 'significant' than if their results are negative or inconclusive, and so the studies available for review are biased in favour of those with positive outcomes. Correcting for this bias is not possible without making untestable assumptions. In this paper, a sensitivity analysis is suggested which is based on fitting a model to the funnel plot. Some examples are discussed.

Journal Article↗
PubMed2000

Correlation of bFGF, FGFR-1 and VEGF expression with vascularity and malignancy of human astrocytomas.

OBJECTIVE: To investigate the correlation of angiogenic factor expression levels with the degrees of malignancy and vascularity and their clinicopathologic significance in astrocytomas. STUDY DESIGN: Factor VIII-related antigen (FVIII-RAg) was used as the marker of endothelia and basic fibroblast growth factor (bFGF); FGF receptor (FGFR)-1 and vascular endothelial growth factor (VEGF) were qualitatively and quantitatively detected with immunohistochemistry and image analysis in 61 brain astrocytomas. The correlation with tumor grades, angiogenesis and prognosis was studied. RESULTS: Measurement of FVIIIRAg expression could describe endothelial proliferation and vascularity, which were related to grade of tumor and prognosis. bFGF and VEGF expression levels in neoplastic astrocytes and endothelia were significantly different in various grades of astrocytoma. These angiogenic factors affected the positive reaction areas and integral optical densities of FVIII-RAg as well as survival time. In contrast, the expression of FGFR-1 was related to neither bFGF nor FVIIIRAg and had no significant effect on tumor malignancy. CONCLUSION: Positive regulation by bFGF and autocrine/paracrine VEGF contributes to the growth and angiogenesis of astrocytomas. Measurement of endothelial cell proliferation with FVIIIRAg in tumor stroma and quantitative detection of angiogenic factor levels in neoplastic cells had prognostic value in brain astrocytomas. The results also indicate that inhibiting bFGF and VEGF expression and/or blocking their effects could be a very useful therapeutic strategy for malignant gliomas.

Astrocytoma↗
PubMed2000

Pathologic significance of proliferative activity and oncoprotein expression in astrocytic tumors.

OBJECTIVE: To clarify the clinicopathologic significance of immunohistochemistry for proliferative activity and oncoprotein expression in astrocytic tumors. STUDY DESIGN: Ninety-seven cases of brain astrocytic tumors with histologic grading and follow-up data were investigated with immunohistochemistry and image analyzer to detect the expression of proliferating cell nuclear antigen (PCNA), silver-binding nucleolar organizer regions (AgNORs) and several oncoproteins. RESULTS: PCNA was significantly related to AgNORs, grading and prognosis of astrocytomas. The frequency of mutant p53 protein expression was higher in grade 2-4 astrocytomas than in grade 1. Epidermal growth factor (EGF) (37.1%), EGF receptor (83.5%) and p21ras (42.3%) expression levels were related to neither the grade nor prognosis of the tumors. The positive ratios of p53 antibodies were higher in grades 2-4 than in grade 1, and the intensities correlated with PCNA but not with prognosis. CONCLUSION: Aberrations of c-erbB-2, p21ras, EGF and EGF receptor might be early events in the initiation and progression of astrocytomas, whereas p53 overexpression is involved in all the stages. Immunohistochemical detection had no prognostic value. PCNA could be important to the evaluation of astrocytoma malignancy.

Astrocytoma↗
PubMed1994

[A comparative study of the expression of ras oncogenic protein P21 and oncofetal protein AFP, CEA in human hepatocellular carcinoma (HCC)].

The expression of P21, AFP and CEA were detected in human hepatocellular carcinoma and its surrounding nontumor tissues by immunohistochemical staining on serial sections. The significance of AFP and P21 in HCC auxiliary diagnosis was discussed. The results are as follows: (1) AFP and P21 were more closely related with HCC than CEA. Both AFP and P21 were expressed simultaneously in more than half the cases. The distribution of these two antigens in HCC was similar. (2) The positive incidence of AFP in tumor tissues was higher than that in surrounding nontumor tissues, but vice versa for P21. Based on the results of this study, we regard that AFP is a relatively specific marker of HCC, better than P21 in auxiliary diagnosis of HCC. The hepatocytes which surround the tumor and can simultaneously express AFP and P21, are likely to be precancerous cells which have been initiated and possess the ability of neoplastic growth but lack phenotype transformation.

Adult↗
PubMed1992

Detection of antigens associated with lung carcinoma in sera by monoclonal antibodies WLA-2C4 and CL-3.

The levels of tumor-associated antigens (TAAS) corresponded to monoclonal antibodies WLA-2C4 and CL-3 in sera of 57 lung cancer patients, 100 healthy adults and 50 non-tumor disease patients were assayed with SABC-ELISA of immunobinding inhibition test. The threshold values of WLA-2C4 and CL-3 (RBI) were 12% and 36%, respectively. The positive results of lung carcinomas with at least one of the two TAAS were as follows: squamous cell carcinoma 89%; adenocarcinoma 83%; small cell carcinoma 67% and their mean positive rate was 79%. Whereas the positive rate in healthy adults and non-tumor disease patients was only 6%. These results indicate that using monoclonal antibodies WLA-2C4 and CL-3 simultaneously may be helpful to the serological diagnosis of lung carcinoma.

Adenocarcinoma↗
PubMed1992

[Studies on the triterpenoid saponin of Cinopodium chinense (Benth) O. Kuntze].

A new triterpenoid saponin named clinopodiside was isolated from Clinopodum Chinense (Benth) O. Kuntze. The structure of clinopodiside A was elucidated by spectroscopic and X-ray diffraction analysis as 3-O-beta-D-glucopyranosyl (1----6)-[beta-D-glucopyranosyl (1----4)]-beta-D-glucopyranosyl-olean-11, 13 (18)-diene-3 beta, 16 beta, 23, 28-tetrol.

Drugs, Chinese Herbal↗
PubMed1989

[Histopathological and ultrastructural changes of canine tracheo-bronchi and lung parenchyma after smoke inhalation injury].

Thirty four male mongrel dogs weighing 10-14 kg were used and divided into 2 groups, i.e. experimental group (N-22) and control group (N-12). Animals of the experimental group were sacrificed at the end of 2 (N-5), 6 (N-7), and 24 (N-10) hr after injury. Tissue samples were taken from the trachea, right main bronchus and both lungs of both groups for LM; specimens for EM were taken from trachea, right main bronchus, right lobar bronchus, and right lung in experimental (N-20) and control groups (N-8). LM Findings: In experimental group, at 2 hr after injury, there were necrosis, hyperemia, edema and leucocytic infiltration in tracheal and main bronchial walls; and occasionally acute bronchitis, bronchiolitis, and lobular pneumonia were seen. The lesions became more marked and increased in frequency with the passage of time. At 6 hr, intra-alveolar edema as well as perivascular edematous or/and hemorrhagic cuffs were demonstrated and became more prominent at 24 hr. Goblet cells in the tracheo-bronchial mucosae showed increase in number. EM Findings: At 2 hr post-injury, there was interstitial edema of the thick portions of alveolar septa, presence of platelets and/or leucocytes in the lumina of capillaries, and slight intracellular edema of Type I and Type II pneumocytes. With the passage of time, these changes became more marked and increased in frequency. At 24 hr postinjury, proliferation of Type II pneumocytes might be found. The etiological factors and pathogenesis concerning smoke inhalation injury were briefly discussed.

Animals↗
PubMed1985

Histopathological and ultrastructural change in liver tissue from burned patients.

Histopathological studies were made on samples of liver and spleen tissue taken post mortem from 59 patients with severe burns. Samples from 8 patients were also studied using the transmission electron microscope. The main pathological findings were degeneration and necrosis of hepatic cells and proliferation of Kupffer cells showing active phagocytosis. Their causes in relation to the time of death after burning and severity of injury have been discussed. The proliferation of Kupffer cells may be a compensatory reaction to the severe splenic injury seen in the patients.

Adolescent↗