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At least 721 records · Page 40Linked to original sources
PubMed1989

Prognostic factors in inoperable adenocarcinoma of the lung: a multivariate regression analysis of 259 patients.

The prognostic factors for survival in advanced adenocarcinoma of the lung were investigated in a consecutive series of 259 patients treated with chemotherapy. Twenty-eight pretreatment variables were investigated by use of Cox's multivariate regression model, including histological subtypes and degree of differentiation, the new international staging system for lung cancer, and seven laboratory parameters. Staging of the patients included bone marrow examination but were otherwise nonextensive without routine bone, liver, and brain scans. Factors predicting poor survival were low performance status, stage IV disease, no prior nonradical resection, liver metastases, high values of white blood cell count, and lactate dehydrogenase, and low values of asparatate aminotransaminase. The nonradical resection may not be a prognostic factor because of the resection itself but may rather serve as an indicator for patients having minimal disease spread. Liver metastases were of limited clinical value as a prognostic factor because they were detected in only seven cases in this patient population. A new Cox analysis ignoring the influence of this variable revealed no other variables than those occurring in the former Cox model to be of importance (performance status, stage, surgical resection, WBC, aspartate aminotransaminase, and lactate dehydrogenase). This simplified model appears to be a feasible clinical tool, allowing for prognostic stratification of patients when first the inoperability of the patient is known.

Adenocarcinoma↗
PubMed2005

Better prediction of protein contact number using a support vector regression analysis of amino acid sequence.

BACKGROUND: Protein tertiary structure can be partly characterized via each amino acid's contact number measuring how residues are spatially arranged. The contact number of a residue in a folded protein is a measure of its exposure to the local environment, and is defined as the number of Cbeta atoms in other residues within a sphere around the Cbeta atom of the residue of interest. Contact number is partly conserved between protein folds and thus is useful for protein fold and structure prediction. In turn, each residue's contact number can be partially predicted from primary amino acid sequence, assisting tertiary fold analysis from sequence data. In this study, we provide a more accurate contact number prediction method from protein primary sequence. RESULTS: We predict contact number from protein sequence using a novel support vector regression algorithm. Using protein local sequences with multiple sequence alignments (PSI-BLAST profiles), we demonstrate a correlation coefficient between predicted and observed contact numbers of 0.70, which outperforms previously achieved accuracies. Including additional information about sequence weight and amino acid composition further improves prediction accuracies significantly with the correlation coefficient reaching 0.73. If residues are classified as being either "contacted" or "non-contacted", the prediction accuracies are all greater than 77%, regardless of the choice of classification thresholds. CONCLUSION: The successful application of support vector regression to the prediction of protein contact number reported here, together with previous applications of this approach to the prediction of protein accessible surface area and B-factor profile, suggests that a support vector regression approach may be very useful for determining the structure-function relation between primary protein sequence and higher order consecutive protein structural and functional properties.

Algorithms↗
PubMedDate not supplied

[Regression analysis of various results of hypercapnia test].

A comparative analysis of different statistic methods for determining individual reactivity of the respiratory system has been made. A mathematical model of ventilation dependence on partial pressure of carbon dioxide has been suggested. It has essential advantage as compared to those used before.

Adolescent↗
PubMedDate not supplied

Regression analysis of use-dilution disinfectant test data as an alternative to current registration practices.

The historical application of probit analysis applied to the use-dilution disinfectant test is discussed. Attention is focused on earlier work which either deleted or incompletely applied confidence limits leading to much current controversy in disinfectant test interpretation. It is proposed that the probit analysis approach applied to disinfectants is indeed feasible and that a more complete application of confidence limits to the assay will yield more reliable data than those currently required for disinfectant product registration with the Environmental Protection Agency. A suggested modified registration protocol using probit analysis is offered as an alternative to the current registration guidelines.

Disinfectants↗
PubMed1987

Histologic malignancy grading of invasive ductal breast carcinoma. A regression analysis of prognostic factors in low-risk carcinomas from a multicenter trial.

In a prospective adjuvant trial including patients with primary operable breast cancer, invasive carcinomas of ductal type were subjected to histological malignancy grading. The parameters investigated were tubule formation, number of mitoses and cell pleomorphism. A Cox regression model for survival data was applied to evaluate the impact of the histological parameters on prognosis in 1809 patients with low-risk carcinomas. Cell pleomorphism proved superior to the other histologic tumor characteristics. It was found that low-risk invasive ductal carcinomas with severe cell pleomorphism had an excess recurrence intensity of 209% relative to carcinomas with no pleomorphism. It is therefore suggested that polymorphous invasive ductal breast carcinomas, other things being equal, should be regarded as high-risk tumors in future clinical trials. Finally it was found that the tripartite malignancy grading 1, 2 and 3 characterizing each of the histological parameters was not equidistant. Consequently, the traditional tripartite histologic scoring needs reconsideration.

Adult↗
PubMed1982

Regression analysis of cytopathological data.

Epithelial cells from the human body are frequently labelled according to one of several ordered levels of abnormality, ranging from normal to malignant. The label of the most abnormal cell in a specimen determines the score for the specimen. This paper presents a model for the regression of specimen scores against continuous and discrete variables, as in host exposure to carcinogens. Application to data and tests for adequacy of model fit are illustrated using sputum specimens obtained from a cohort of former asbestos workers.

Adult↗
PubMed1985

A logistic regression analysis of multiple noninvasive tests for the prediction of the presence and extent of coronary artery disease in men.

The incremental diagnostic yield of clinical data, exercise ECG, stress thallium scintigraphy, and cardiac fluoroscopy to predict coronary and multivessel disease was assessed in 171 symptomatic men by means of multiple logistic regression analyses. When clinical variables alone were analyzed, chest pain type and age were predictive of coronary disease, whereas chest pain type, age, a family history of premature coronary disease before age 55 years, and abnormal ST-T wave changes on the rest ECG were predictive of multivessel disease. The percentage of patients correctly classified by cardiac fluoroscopy (presence or absence of coronary artery calcification), exercise ECG, and thallium scintigraphy was 9%, 25%, and 50%, respectively, greater than for clinical variables, when the presence or absence of coronary disease was the outcome, and 13%, 25%, and 29%, respectively, when multivessel disease was studied; 5% of patients were misclassified. When the 37 clinical and noninvasive test variables were analyzed jointly, the most significant variable predictive of coronary disease was an abnormal thallium scan and for multivessel disease, the amount of exercise performed. The data from this study provide a quantitative model and confirm previous reports that optimal diagnostic efficacy is obtained when noninvasive tests are ordered sequentially. In symptomatic men, cardiac fluoroscopy is a relatively ineffective test when compared to exercise ECG and thallium scintigraphy.

Adult↗
PubMed1980

Two-compartment Markov regression analysis.

This paper presents a computer program for estimating transition rates between states in a two-compartment Markov process, where the rates are functions of covariates. Parameters are estimated by the method of maximum likelihood using the Newton-Raphson iterative procedure. The program provides statistics for testing hypotheses concerning regression coefficients and calculates observed versus expected values in order to assess the fit of the model to the data.

Age Factors↗
PubMed1997

Plasma volume estimation using indocyanine green with biexponential regression analysis of the decay curves.

We studied seven analytical methods of estimating the plasma volume from the decay curves of indocyanine green. Fifteen volunteers received 1.0 mg.kg-1 of the dye by intravenous injection and the plasma concentration was measured continuously using spectrophotometry. Plasma volumes were calculated using three single-regression methods (1-a, 1-b, 1-c) and four biexponential regression methods (2-a, 2-b, 2-c, 2-d). The means (SD) of 1-a, 1-b and 1-c were 39 (5.0), 44 (5.7) and 54 (11.5) ml.kg-1, respectively, and these were significantly different from each other (p < 0.05). The values for methods 2-b, 2-c and 2-d were similar to each other: 39 (4.6), 40 (4.1) and 40 (4.0) ml.kg-1, respectively. These required more than 3 min circulation or mixing time. When the time allowed for mixing was less than 3 min (method 2-a) the plasma volume was underestimated. We conclude that plasma volume estimation using indocyanine green and spectrophotometry is most accurate when the mixing time is adequate (3-5 min) and the decay curves are analysed using biexponential regression.

Adult↗