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Results for “correlation matrix”

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PubMed2006

Increased expression of membrane-type matrix metalloproteinase-1 is correlated with poor prognosis in patients with osteosarcoma.

Numerous studies have demonstrated a correlation of matrix metalloproteinase (MMP) overexpression with the prognosis of various kinds of cancer. The current study investigated whether the expression of MMPs is correlated with the prognosis of osteosarcoma. Expression levels of MMP-2, -9, MT1-MMP and TIMP-2 were examined immunohistochemically in samples from 47 patients with osteosarcoma. Correlation of the positivity of staining with prognosis was analyzed with the Kaplan-Meier method, and statistically analyzed with log-rank test. Co-localization of MMP-2, MT1-MMP and TIMP-2 was determined by double staining with fluorescence-conjugated antibodies. Activities of gelatinases in representative tissues were examined with gelatin zymography. MMP-2 was expressed strongly in 60% of cases (28/47), and MMP-9, MT1- MMP and TIMP-2 was strongly positive in 61% (29/47), 45% (21/47), and 91% (43/47), respectively. Increased MT1-MMP expression was associated significantly with poor prognosis in overall survival (P=0.0480). In cases of overexpression for both MMP-2 and MT1-MMP, there was a tendency for poor prognosis (P=0.0969). In 36 cases who underwent neoadjuvant chemotherapy, wide resection of the tumors and post-operative adjuvant chemotherapy, increased expression of MT1-MMP resulted in a significant negative prognostic factor for disease-free survival (P=0.0143). Also, co-overexpression of MT1-MMP and MMP-2 showed a tendency to correlate to the reduced disease-free survival (P=0.0502). Increased gelatinase activity was observed in tissues of co-overexpression of MT1-MMP and MMP-2. The results of this study demonstrate the correlation of MT1-MMP expression and the oncological outcome of osteosarcoma patients, suggesting the prognostic significance of these proteins in osteosarcoma patients.

Adolescent↗

PubMed1981

Postoperative wound infection: application of multiple regression analysis to patients parameters.

The effect of patient parameters (age, sex, wound drainage, and wound description) on postoperative wound infection is evaluated with the aid of multiple regression analysis. The resulting multiple correlation matrix confirmed that the four parameters are not correlated. Hence, the possibility that parameter interactions introduce a bias into the observations was excluded. In the multiple regression model developed, the regression coefficients of all four parameters were statistically significant. When the relative significance of each parameter was considered, the most significant one was wound contamination, followed by the presence of wound drains. The least significant were the patient's age and sex. Male sex was a relatively more significant parameter when compared with age up to 42 years. However, beyond that critical point patient age appear to be relatively more significant than male sex. The usefulness of the model developed and possible application areas are fully discussed.

Adult↗

PubMed2001

Data clustering and noise undressing of correlation matrices.

We discuss an approach to data clustering. We find that maximum likelihood leads naturally to an Hamiltonian of Potts variables that depends on the correlation matrix and whose low temperature behavior describes the correlation structure of the data. For random, uncorrelated data sets no correlation structure emerges. On the other hand, for data sets with a built-in cluster structure, the method is able to detect and recover efficiently that structure. Finally we apply the method to financial time series, where the low-temperature behavior reveals a nontrivial clustering.

Journal Article↗

PubMed2005

Prognostic value of Bax, Bcl-2, p53, and TUNEL staining in patients with radically resected ampullary carcinoma.

BACKGROUND: There is a lack of data in the literature concerning the identification of potential prognostic factors in ampullary adenocarcinoma. AIMS: To examine the prognostic significance of Bax, Bcl-2, and p53 protein expression and the apoptotic index in a large cohort of uniformly treated patients with radically resected ampullary cancer. METHODS: All patients with a pathological diagnosis of ampullary cancer and radical resection were evaluated. Expression analysis for p53, Bax, and Bcl-2 was performed by immunohistochemistry. Apoptotic cells were identified by terminal deoxynucleotidyl transferase mediated dUTP nick end labelling (TUNEL). RESULTS: Thirty nine tumour specimens from patients with radically resected ampullary adenocarcinoma were studied. A positive significant correlation between Bax and p53 expression was found by rank correlation matrix (p < 0.001). A trend towards a positive correlation was found between the apoptotic index and p53 expression (p = 0.059). By univariate analysis, overall survival was influenced by Bax expression, p53 expression, and TUNEL staining (p = 0.001, p = 0.01, and p = 0.03, respectively). Bcl-2 expression did not influence overall survival in these patients (p = 0.55). By multivariate Cox regression analysis, the only immunohistochemical parameter that influenced overall survival was Bax expression (p = 0.020). CONCLUSIONS: These results provide evidence that apoptosis may be an important prognostic factor in patients with radically resected ampullary cancer. This study is the first to assess the clinical usefulness of Bax expression in radically resected ampullary cancer.

Adenocarcinoma↗

PubMed2000

Myocardial architecture, texture and left ventricular heterogeneity in the pulsed Doppler tissue imaging pattern.

The regional contribution for the global ventricular functional performance is complex and heterogeneous, the myocardial texture could reflect this particular aspect, during the phases of myocardial contraction and relaxation. The objective of our clinical study was to evaluate the relationship between the segmental myocardial velocity pattern by Doppler tissue imaging and the ultrasound characteristics of the left ventricular myocardium analysed by computerized ultrasound densitometry with the calculation of its intensity (dB), in a population of 22 subjects without clinical history of cardiovascular pathology, 50% female gender, mean age 43 +/- 11 years (19-66 years). In the methodology of study, the left ventricular myocardium was divided in 16 segments, according with the transthoracic echocardiographic recommendations of the American Society of Echocardiography (A.S.E.). During one cardiac cycle interval, the ultrasound characteristics of the left ventricular myocardium were evaluated continuously and in a quantitative manner, applying the computerized ultrasound densitometry method on the gray scale images of the ventricular myocardium, with the sample size identical to the myocardial wall thickness. The peak (Vmax-cm/sec) and mean (Vm-cm/sec) pulsed Doppler tissue imaging velocities, individuals, segmental and a total velocities, contraction and relaxation velocities of the left ventricular myocardium were obtained immediately after the computerized ultrasound densitometry analysis. Ultrasound densitometry and Doppler tissue imaging data were obtained in a total number of 352 left ventricular myocardial segments. Using the multiple linear correlation matrix analysis, the ultrasound intensity registered inverse significant correlation's with the Doppler tissue imaging Vmax and Vm for the systolic "s" wave in the total segments and each one of them (r = -0.66; p = 0.001; interval 2-18 cm/sec; r = -0.52 to -0.70) and with the early diastolic "e" wave (r = -0.42; p = 0.01; interval 2-19 cm/sec; r = -0.35 to -0.55). Direct correlation's were obtained for the computerized ultrasound densitometry intensity and Doppler tissue imaging Vmax and Vm of the late diastolic "a" wave in the total number of the left ventricular myocardial wall segments and in each one of them (r = 0.51; p = 0.01; interval 1-17 cm/sec; r = 0.42 a 0.66). We conclude that in our study and under physiological conditions of myocardial performance, a direct correlation was obtained between the ultrasound characteristics of the ventricular myocardial imaging and its velocities of contraction and relaxation. These facts reflect the close relationship between left ventricular myocardial structure and function, analyzed by the new ultrasound Doppler technologies.

Adult↗

PubMed1992

Manometric and radiologic correlations in achalasia.

Achalasia is an esophageal motor disorder distinguished by clinical, radiologic, and manometric features. To evaluate the correlation among these features, we studied 109 achalasia patients. The four most common clinical complaints, the four most commonly encountered radiologic findings, and two manometric parameters were analyzed with a correlation matrix test and a multiple regression analysis. Significant correlation existed among symptoms of dysphagia, regurgitation, and weight loss. In contrast, chest pain inversely correlated with these symptoms. Dysphagia and weight loss significantly correlated with a bird-beak deformity but not with esophageal dilatation or a sigmoid esophagus. Moreover, no significant relationship between lower esophageal sphincter pressure and esophageal dilatation or sphincter pressure and sigmoid esophagus was found. However, in those patients with a resting lower esophageal sphincter pressure greater than 45 mm Hg, a reasonable correlation among clinical, radiologic, and manometric parameters did exist. In conclusion, although in a subset of patients with markedly increased lower esophageal sphincter pressure, a good correlation between clinical, radiologic, and manometric findings exists, such a correlation cannot be established in all of the achalasia patients; esophageal dilatation or a sigmoid esophagus may not be due to a hypertensive sphincter, and their presence must not necessarily be interpreted as an indication of severity of the disease; there is an inverse correlation between chest pain and symptoms of dysphagia, regurgitation, and weight loss; and finally, achalasia and hiatal hernia may coexist in 6% of the patients.

Adolescent↗

PubMed1983

Factors associated with infections among breast-fed babies and babies fed proprietary milks.

Correlation of first postnatal year infections among 251 babies was made with the infant feeding mode, socioeconomic status of family, maternal educational level, age, and maternal behavioral factors including smoking habit and number of siblings in the family. Initially, 127 mothers intended to breast-feed and 124 intended to formula-feed their infants. In the correlation matrix maternal education was the highest variable inversely correlated with infection; it was the first to enter in stepwise regression analysis and was highly significant (P less than .0001). Maternal weight gain during pregnancy and infant feeding mode were the next two variables, respectively, to be added during the stepwise regression but they were not significant in the presence of maternal education. The statistical significance of increased maternal education in inverse relation to infection persisted in the presence of the other two factors (P less than .0064). The t test showed no significant difference in the number of infections among the breast-fed and formula-fed babies within any of the three maternal education groups. It may be concluded that in the population studied, the infant feeding mode itself was not significantly related to the number of infections during the infant's first postnatal year when the education of the mother was taken into account.

Adult↗

PubMed1994

Genetic and environmental correlations among skinfold measures.

A bivariate genetic analysis, utilizing variance decomposition techniques based on maximum likelihood methods, was undertaken to examine the genetic and environmental correlations among eight skinfolds in a large pedigreed sample of Mexican Americans from San Antonio, Texas. The resulting correlation coefficients reveal significant values for both the genetic and environmental components among the traits examined. The genetic correlation coefficients showed the highest values between skinfolds from the same region (i.e., triceps, biceps, and forearm), while the environmental correlation remained fairly constant between all traits. These findings are further supported by a principal component analysis of the phenotypic, genetic, and environmental correlation matrices. This represents the first study to partition the phenotypic correlation between these traits into their genetic and environmental components. An examination of the graphical representations of the eigenvectors of these correlation matrices reveals that the patterns of central versus peripheral fat distribution seen in the phenotypic correlation matrix are largely a function of the genetic correlation structure. All these findings are interpreted as evidence of a global pleiotropic effect in the genetic expression of these traits, with what might be secondary regional pleiotropic effects among specific subsets of the skinfolds. In addition it appears that these pleiotropic effects exist against a background of a relatively constant shared environmental effect. It is concluded that these traits are not independent with respect to either shared genetic or environmental influences.

Adolescent↗

PubMed1995

Robust elementwise estimation of a dispersion matrix.

Most of the existing robust methods for estimating a covariance or correlation matrix involve a multivariate approach in which matrix elements are estimated via simultaneous manipulation of all variables. These methods are generally based on complex iterative algorithms and hence are rather difficult to implement. The purpose of this article is to recommend an easy to implement noniterative robust method for estimating a dispersion matrix, based on an elementwise estimation approach. Simple expressions are provided for robust estimators of variances and covariances based, in part, on a modified A-estimator of scale discussed previously by Lax (1985, Journal of the American Statistical Association 80, 736-741). A Monte Carlo study is used to compare the performance of the proposed noniterative method with that of some iterative procedures studied in the literature. A numerical example involving robust estimation of variance components is presented as an application of the proposed methodology.

Analysis of Variance↗

PubMed2000

Canonical correlation and chi-square: relationships and interpretation.

A 2 x 2 chi-square can be computed from a phi coefficient, which is the Pearson correlation between two binomial variables. Similarly, chi-square for larger contingency tables can be computed from canonical correlation coefficients. The authors address the following series of issues involving this relationship: (a) how to represent a contingency table in terms of a correlation matrix involving r - 1 row and c - 1 column dummy predictors; (b) how to compute chi-square from canonical correlations solved from this matrix; (c) how to compute loadings for the omitted row and column variables; and (d) the possible interpretive advantage of describing canonical relationships that comprise chi-square, together with some examples. The proposed procedures integrate chi-square analysis of contingency tables with general correlational theory and serve as an introduction to some recent methods of analysis more widely known by sociologists.

Chi-Square Distribution↗

PubMed2006

Volumetric quantitative computed tomography of the proximal femur: relationships linking geometric and densitometric variables to bone strength. Role for compact bone.

INTRODUCTION: In assessing cervical fractures of the proximal femur, this in vitro quantitative computed tomography (QCT) study had three objectives: to compare QCT to dual-energy X-ray absorptiometry (DXA) for predicting the failure load of the proximal femur, to compare the contributions of density and geometry to bone failure load, and to compare the contributions of cortical and trabecular bone to bone failure load. A novel three-dimensional (3D) analysis tool [medical image analysis framework (MIAF-Femur)] was used to analyze QCT scans. METHODS: The proximal ends of 28 excised femurs were studied (1) using QCT to separately measure bone mineral density (BMD) and geometric variables of trabecular and cortical bone, (2) using mechanical tests to failure in a stance configuration, and (3) using DXA to measure BMD. The variables were described with mean, standard deviation, and range. Correlation matrix and multivariate linear models were computed. RESULTS: Among correlations, cortical thicknesses of the femoral neck were significantly correlated with femoral failure load, especially of the inferoanterior quadrant (r2=0.41; p<0.001), as was cortical volume at the "extended neck" (r2=0.41; p<0.001). Femoral failure load variance was best explained by a combination of QCT variables. Combining densitometric and geometric variables measured by QCT explained 76% of femoral failure load variance compared with 69% with the DXA model. Geometric variables (measured by QCT) explained 43% of femoral failure load variance compared with 72% for densitometric variables (measured by QCT). A model including only trabecular variables explained 52% of femoral failure load variance compared with 59% for a model including only cortical variables. CONCLUSION: The QCT-MIAF reported here provides analysis of both geometric and densitometric variables characterizing cortical and trabecular bone. Confirmation of our results in an independent sample would suggest that QCT may better explain failure load variance for cervical fracture than the gold standard DXA-provided BMD.

Absorptiometry, Photon↗

PubMed2006

Correlation among cadmium levels in river sediment, in rice, in daily foods and in urine of residents in 11 prefectures in Japan.

OBJECTIVE: The objective of this study is to examine if overall correlation exists among cadmium levels (Cd) in the general environment, dietary Cd intake, and Cd body burden of local residents. METHODS: Eleven prefectures in Japan were selected as the areas where large-scale data on Cd levels in urine of adult women (40-49 and 50-59 years of age, respectively) were available to calculate geometric mean (GM) values for each of the prefecture. Other data were cited from published or previously established databases on Cd in the sediments of river bottoms (as a representative of Cd in the environment), Cd in rice for local consumption, and Cd in daily food duplicate samples collected from local women populations, and calculated for GM values for the prefectures. The GM values were subjected to correlation matrix and regression analysis. RESULTS: Marginally significant (P < 0.10) correlation was detected between Cd in sediment and Cd in rice. Furthermore, correlation of Cd in sediment was significant with Cd in total foods (P < 0.05) and possibly with Cd in urine (P < 0.05-0.10). Importance of data on Cd in rice paddy soil as a missing link is discussed. CONCLUSIONS: Correlation was demonstrated in the flow of Cd transport from the environment (expressed as Cd contents in river sediments) to humans (in terms of Cd in urine) among general populations in Japan.

Adult↗

PubMed2000

Detecting and characterising sources of persistent organic pollutants (PAHs and PCBs) in surface sediments of an industrialized area (harbour of Trieste, northern Adriatic Sea).

A sediment sampling based on a two-dimensional mapping was performed in the harbour of Trieste (northern Adriatic Sea), considering 28 sites exposed to pollutant inputs from harbour and industrial activities. Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were determined in surface sediments, because these very persistent pollutants seem to be responsible for the depletion of benthic populations observed in this area. The correlation matrix indicates that PAHs and PCBs are non-correlated, and probably have different sources. Both cluster analysis performed on the sampling sites and graphical drawing of the PAH sediment contents make it possible to locate along the shoreline a band of more polluted sediments, clustered around a site facing a steelmaking factory, to be considered as the main source point for PAHs. The evaluation of phenanthrene to anthracene (P/AN) and fluoranthene to pyrene (FL/PY) ratios permits the assessment of the pyrolytic, industrial origin of these PAHs, rejecting a second possible source of hydrocarbons (i.e., an oil-pipeline terminal, situated near the steelmaking factory). Graphical drawing of the total PCB iso-concentrations reveals a different source-point for this other category of very persistent pollutants.

Environmental Monitoring↗

PubMed2004

An analysis of the rollover backstroke turn by age-group swimmers.

Kinetic (3-D force plate), kinematic (videography) and temporal characteristics of backstroke turns by 20 male and 16 female swimmers were recorded to identify and describe key elements of backstroke turning performance. Data were recorded during a 50 m maximum effort swim in a 25 metre pool. A Pearson product moment correlation matrix revealed that the 5 m RTT was significantly correlated with anthropometric measures of height, mass, trochanteric height and age; kinetic measures of horizontal impulse and peak force; and kinematic measures of wall contact time and peak velocity. The stepwise multiple regression equation to predict 5 m RTT was: 19.6-0.75 trochanteric height-1.8 wall exit velocity-0.03 peak vertical force. Four key factors were identified from a principle components factor analysis--anthropometry and force, post-turn velocity, force preparation and rotational skills. Implications from the findings were that age-group backstrokers should 'hit the wall hard' with relatively extended legs to reduce swim distance and push-off deceleration; use minimal wall contact time, and maximise forces to develop high horizontal velocities in a streamlined position.

Anthropometry↗

PubMed1980

Assessment of anger arousal.

Reasons for the paucity of research on anger are discussed and four measures of anger arousal are reviewed: Buss Durkee Hostility Inventory, Reaction Inventory, Anger Self-report, and Anger Inventory. Normative data are reported for 150 subjects and sex differences are assessed. A correlation matrix presents intercorrelations for all anger scales and also correlations between the scales and social desirability. Factor analysis revealed five separate factors which accounted for the total variance. The research utility of each of the scales is assessed, clinical implications noted, and recommendations for furture research made.

Anger↗

PubMed1992

Hippocampal mossy fibres: implication in novelty reactions or in anxiety behaviours?

Hippocampal mossy fibre distribution is known to correlate with various processes including responses to novelty. Unfortunately, these correlations have been calculated using behavioural variables recorded in situations including anxiogenic components and so it is not clear whether the hippocampal trait is related to novelty reactions or to anxiety. In order to better elucidate the functional role of the supra- (SP-MF), intra-infra-(IIP-MF) and dentate gyrus (CA4) mossy fibres synaptic area, we investigated their covariations with behavioural measures recorded in situations related to novelty (free exploration test, confrontation with a novel object) or to anxiety (light/dark choice test). The hippocampus-behaviour correlation matrix reveals that IIP-MF and SP-MF correlate with variables linked to novelty reactions while CA4 correlates with measures related to anxiety.

Animals↗

PubMed2000

Genetic architecture of a wing size measure in Drosophila hibisci from two populations in eastern Australia.

Two models of evolutionary change invoke either additive genetic contributions to phenotypic traits (Fisher) or epistatic as well as additive effects (Wright). An earlier study of the flower-breeding Drosophila hibisci from two sites in eastern Australia reported additive and epistatic genetic effects as well as environmental effects on ovariole number. The present study of the same flies examines the genetic architecture of wing width, a trait that is correlated phenotypically with ovariole number and body size. A generation means analysis of flies reared at 25 degrees C indicated additive and epistatic genetic effects, but no consistent maternal effects, whereas for flies reared at three temperatures (18 degrees C, 21.5 degrees C, and 25 degrees C) linear and nonlinear environmental effects interacted with additive genetic effects. The genetic correlation matrix for ovariole number and wing width suggested negative genetic correlations between additive effects on one trait and epistatic effects on the other. Both traits provide evidence of genetic effects consistent with assumptions of Wright's shifting balance theory of evolution.

Animals↗

PubMed1983

The use of a dynamometer in nutritional assessment.

Standard anthropometric techniques may be unreliable in patients with subcutaneous edema or dehydration. In order to circumvent this dilemma, 98 male subjects were studied utilizing a hand-held dynamometer in conjunction with other nutritional assessment techniques. Following a nutritional assessment using anthropometric measurements, patients were characterized as being well-nourished or malnourished using three definitive measures: percentage of ideal body weight, triceps skinfold, and midarm muscle circumference. Once malnutrition was assessed, no attempt was made to distinguish between marasmus, hypoalbuminemia, or mixed marasmus types of malnutrition. A correlation matrix done between the two groups revealed no statistically significant correlation between any of the measured parameters. Analysis of variance revealed statistically significant correlations between patients in both groups (independent variables) with respect to midarm muscle circumference and dynamometer reading in the dominant arm (dependent variables). Further validation of this technique is required before it can become a standard component of nutritional assessment.

Analysis of Variance↗