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At least 19 recordsLinked to original sources
PubMed1994

Staphylococcus aureus phage typing, antimicrobial susceptibility patterns and patient data correlated using a personal computer: advantages for monitoring the epidemiology of MRSA.

Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA) is an important nosocomial pathogen. A problem encountered in the control of staphylococcal nosocomial infection is the difficulty correlating data available from antimicrobial susceptibility patterns (usually available locally) with phage typing patterns which are generally determined in a reference laboratory. Data problems are exaggerated because many patients have numerous samples taken over long periods of time. This paper describes the use of a database, 'DataEase', on a personal computer to correlate available data with patient demographics and to present the resulting information in whatever format is required. The information might be presented as the phage pattern of each isolate from patients in a particular unit per month or as a combination of the phage types and antimicrobial susceptibility patterns of isolates from a particular unit. The system can be used to generate a list of all isolates for phage typing in a format that allows the phage typing pattern to be recorded directly onto the list worksheet. In addition to providing clinically relevant reports, the system simplifies the collation of epidemiological information, data from which showed that since 1987 the incidence of MRSA has been rising in the group of hospitals served by this laboratory; MRSA of phage type 83A became a problem during 1990 and 1991; the incidence of gentamicin-sensitive phage type non-typable MRSA increased fourfold between 1988 and 1991; and the incidence of gentamicin-resistant MRSA rose sharply in 1992.

Bacteriophage Typing↗
PubMed1997

Development of interpretive breakpoints for antifungal susceptibility testing: conceptual framework and analysis of in vitro-in vivo correlation data for fluconazole, itraconazole, and candida infections. Subcommittee on Antifungal Susceptibility Testing of the National Committee for Clinical Laboratory Standards.

The availability of reproducible antifungal susceptibility testing methods now permits analysis of data correlating susceptibility in vitro with outcome in vivo in order to define interpretive breakpoints. In this paper, we have examined the conceptual framework underlying interpretation of antimicrobial susceptibility testing results and then used these ideas to drive analysis of data packages developed by the respective manufacturers that correlate fluconazole and itraconazole MICs with outcome of candidal infections. Tentative fluconazole interpretive breakpoints for MICs determined by the National Committee for Clinical Laboratory Standards' M27-T broth macrodilution methodology are proposed: isolates for which MICs are < or = 8 microg/mL are susceptible to fluconazole, whereas those for which MICs are > or = 64 microg/mL appear resistant. Isolates for which the MIC of fluconazole is 16-32 microg/mL are considered susceptible dependent upon dose (S-DD), on the basis of data indicating clinical response when > 100 mg of fluconazole per day is given. These breakpoints do not, however, apply to Candida krusei, as it is considered inherently resistant to fluconazole. Tentative interpretive MIC breakpoints for itraconazole apply only to mucosal candidal infections and are as follows: susceptible, < or = 0.125 microg/mL; S-DD, 0.25-0.5 microg/mL; and resistant, > or = 1.0 microg/mL. These tentative breakpoints are now open for public commentary.

Animals↗
PubMedDate not supplied

[Analysis of correlated data in occupational medicine: examples with binary data].

In a previous paper in this Journal we presented and discussed examples of analysis of correlated data when the response variable was continuous and normally distributed (the measurement of exposure to a toxic substance was the case in point). In this paper we extend the analysis and the discussion to take into account categorical (binary) variables (described in terms of proportions or odds); to favour the comprehension of the analogies (and discrepancies) between the two contexts we have fully developed an example that mimics the situation presented in the previous paper. Marginal, conditional, random effects and transitional models for correlated data are introduced in practical terms; the meaning of the different estimates obtained are interpreted for epidemiological purposes; the disadvantages of not considering correlation in the analysis are explained and the complexities connected to this type of analysis are fully appreciated. It is concluded that correlated data are very frequently encountered in occupational settings and that an appropriate analysis is necessary. This analysis requires sophisticated computer programs and statistical expertise, particularly in the case of categorical data.

Cluster Analysis↗
PubMedDate not supplied

[Analysis of correlated data: problems and examples in industrial medicine].

In occupational health we are frequently faced with data that are not independent, but to recognize the lack of such an independence is not yet a common practice. To help researchers in the field to treat correlated data in a proper way this paper has two aims: to highlight practical situations in which the data are not independent and to show the main differences between a statistical analysis which does consider the correlation appropriately and one which doesn't. As to the first aim, four typical examples are discussed: repeated measurements in the same subject (e.g., cells in which the number of sister chromatid exchanges is counted); health effects observed in multiple organs (e.g., visual impairment in both eyes); evaluation of prevention programs (e.g., exposure assessment to styrene before and after environment remediation); longitudinal studies of health effects (e.g., changes over time of pulmonary function parameters). With respect to the second aim a practical exercise is described completely. Measurements of exposure to a toxic substance in two different departments before and after environment remediation are evaluated with statistical tools which both do and do not consider the correlation between such measurements. Differences in the results obtained, with particular reference to indices of variability (e.g., standard errors), point toward the need of analysing correlated data with appropriate statistical tools that take correlation into account.

Analysis of Variance↗
PubMed1996

Ordinal regression methodology for ROC curves derived from correlated data.

We present an approach for the analysis of correlated ROC data, using ordinal regression models in conjunction with generalized estimating equations. The approach applies to the analysis of degree-of-suspicion data derived from multiple interpretations of the same diagnostic study and from the examination of the same patients with multiple diagnostic modalities. The regression models make it possible to incorporate patient and reader characteristics into the analysis, without having to resort to stratification. We illustrate the potential of the approach with analysis of data from two studies in diagnostic oncology.

Diagnosis↗
PubMed2025

Generating correlated data for omics simulation.

Simulation of realistic omics data is a key input for benchmarking studies that help users obtain optimal computational pipelines. Omics data involves large numbers of measured features on each sample and these measures are generally correlated with each other. However, simulation too often ignores these correlations, perhaps due to computational and statistical hurdles of doing so. To alleviate this, we describe three approaches for generating omics-scale data with correlated measures which mimic real datasets. These approaches are all based on a Gaussian copula approach with a covariance matrix that decomposes into a diagonal part and a low-rank part. This decomposition allows for extremely efficient simulation, overcoming a hurdle for adoption of past methods. We use these approaches to demonstrate the importance of including correlation in two benchmarking applications. First, we show that variance of results from the popular DESeq2 method increases when dependence is included. Second, we demonstrate that CYCLOPS, a method for inferring circadian time of collection from transcriptomics, improves in performance when given gene-gene dependencies in some circumstances. We provide an R package, dependentsimr, that has efficient implementations of these methods and can generate dependent data with arbitrary marginal distributions, including discrete (binary, ordered categorical, Poisson, negative binomial), continuous (normal), or with an empirical distribution.

Computer Simulation↗
PubMed1989

Rerandomization tests for analyzing correlated data from dental studies.

Dental research studies often produce relatively small data sets in which observations are serially or spatially correlated. Rerandomization tests are presented as alternatives to analysis of variance and multivariate analysis for assessing group differences using such data. Rerandomization tests are particularly useful when the investigator is unwilling to make strong assumptions about the nature of the serial correlation or the distribution of the data. Two examples are discussed that demonstrate these techniques.

Data Interpretation, Statistical↗
PubMed1993

Probabilistic structure calculations: a three-dimensional tRNA structure from sequence correlation data.

Algorithms based on probability theory can address issues of uncertainty directly through their representational framework and their theory for data combination. In this paper, we discuss the advantages of probabilistic formulations for molecular-structure calculations, describe one implementation of such a formulation, and show its performance on a data set derived from analysis of the statistical correlations within a set of aligned transfer RNA sequences. By assigning reasonable physical interpretations to certain statistical correlations, we are able to calculate three-dimensional structures for tRNA from a random starting structure. The constraints that we use are associated with different variances, and so their effects are not uniform, and must be reconciled by a probabilistic algorithm to yield the most likely structure. As might be predicted, the uncertainty in the position for each base is a function of both the number and strength of the constraints, and is reflected in the variances in atomic position calculated by the algorithm. For example, the hinge region in the tRNA is shown to be the most uncertain. In addition, the algorithm retains information about positional covariation that is useful for understanding the relationships between different parts of the structure. These experiments also demonstrate that we can define a single-sphere representation for each base that is useful for nucleic acid structural calculations in the same way that alpha-carbon representations are useful for protein structural calculations.

Algorithms↗
PubMed1984

Implications of regression analysis and correlational data between subtests of the WISC-R and the PPVT-R for a delinquent population.

Computed correlations between the subscales of the Wechsler Intelligence Scales for Children-Revised (WISC-R) and the Peabody Picture Vocabulary Test-Revised (PPVT-R) using as a sample 72 adjudicated male delinquents aged 13-10 to 16-11. Significant relationships at the .0001 level were obtained for 10 subtests with only one, Object Assembly, computed at the .001 level. A forward selection multiple regression analysis resulted in six subtests of the WISC-R correlating to the PPVT-R with a R2 value of .78. The significance and the implications of this relationship for the juvenile delinquent population were discussed.

Adolescent↗
PubMed1977

Analog processing of vestibular nystagmus for on-line cross- correlation data analysis.

An analog processing circuit is described which allow accurate measurement of the phase relationships between input angular acceleration and resulting eye velocity. Vestibular nystagmic data are processed via analog technics to yield slowphase eye velocity. The turntable velocity input is cross-correlated with the eye velocity output, using a Nicolet MED-80 minicomputer system. The resulting correlograms are further processed to obtain precise phase information. Test data analysis shows a system resolution within 1 degree. Data from human and animal subjects are portrayed.

Acceleration↗
PubMed1986

New hydrophilicity scale derived from high-performance liquid chromatography peptide retention data: correlation of predicted surface residues with antigenicity and X-ray-derived accessible sites.

A new set of hydrophilicity high-performance liquid chromatography (HPLC) parameters is presented. These parameters were derived from the retention times of 20 model synthetic peptides, Ac-Gly-X-X-(Leu)3-(Lys)2-amide, where X was substituted with the 20 amino acids found in proteins. Since hydrophilicity parameters have been used extensively in algorithms to predict which amino acid residues are antigenic, we have compared the profiles generated by our new set of hydrophilic HPLC parameters on the same scale as nine other sets of parameters. Generally, it was found that the HPLC parameters obtained in this study correlated best with antigenicity. In addition, it was shown that a combination of the three best parameters for predicting antigenicity further improved the predictions. These predicted surface sites or, in other words, the hydrophilic, accessible, or mobile regions were then correlated to the known antigenic sites from immunological studies and accessible sites determined by X-ray crystallographic data for several proteins.

Amino Acids↗
PubMed1990

The relationship between situational stress and phantom limb pain: cross-lagged correlational data from six month pain logs.

This study reports the results of the first investigation into the relationship between situational stress and phantom limb pain. Twenty-seven male amputees recorded their pain and overall stress levels daily for 180 days using a 1-10 rating scale. Three possible relationships into the etiology and/or maintenance of phantom limb pain were examined using cross-lagged correlational techniques: an isomorphic relationship (same time increases in pain lead to same time increases in stress and vice versa), a consequence relationship (increases in pain precede increases in stress), and a precursor relationship (increases in stress precede increases in pain). Thirty-seven per cent of subjects demonstrated some significant precursor relationship. Although support was found for all three hypotheses, the most frequently observed relationship was the isomorphic one. Seventy-four per cent of subjects demonstrated some significant stress-pain relationship. The results lend support to the psychological theory underlying the use of psychophysiological interventions such as biofeedback and relaxation therapy in amputees with phantom limb pain.

Adult↗
PubMed1985

The degree to which myocardial infarct site and size determine the electrocardiographic axis. Analysis of correlative data by computational modeling.

The spatial electrical QRS axis was determined for 428 twelve-lead electrocardiograms from patients subsequently shown by postmortem dissection to have ventricular myocardial fibrosis or necrosis. Four 16-segment ventricular models of the heart were used to "predict" the spatial electrical QRS axis from known ventricular mass and deficit. The raw model I in ideal anatomic position and vectors perpendicularly outward for each muscle segment showed a mean correlation value of -0.494; model II was rotated in the chest to produce best fit with a correlation of 0.638, but the anatomic orientation was not reasonable; model III maintained original position and orientation but the vectors were scaled (correlation 0.780); and model IV, with nonperpendicular vectors, yielded a mean correlation of 0.793. The exceptions to good predictability formed a distinct subset largely composed of electrocardiograms with some form of variant intraventricular conduction (slight QRS widening, fascicular block patterns and "indeterminate frontal-plane axis").

Electrocardiography↗
PubMed1995

Improved electrocardiographic detection of echocardiographic left ventricular hypertrophy: results of a correlated data base approach.

OBJECTIVES: We used electrocardiographic (ECG) and echocardiographic measurements from 3,351 adults from the Framingham Heart Study to evaluate the performance of 10 ECG criteria in detecting left ventricular hypertrophy before and after adjustment for gender, age and obesity. BACKGROUND: Significant improvement in the sensitivity and specificity of ECG voltage-based criteria for detection of echocardiographic left ventricular hypertrophy using gender-specific criteria adjusted for age and obesity has been demonstrated. METHODS: Gender-specific correlation and regression analyses were used to identify the five most sensitive ECG criteria and to adjust them for age and obesity. Standard and truncated receiver operating characteristic curves were used to compare the selected criteria. RESULTS: Linear regression of left ventricular mass on ECG voltages, body mass index and age yielded considerably stronger relations for women than for men because of the greater correlation between ventricular mass and body mass index in women. Obesity and age adjustment of the five voltage criteria produced considerable improvement in their performance. The voltage sum of the R wave in lead aVL and the S wave in lead V3, alone and in combination with QRS duration, had a sensitivity at 95% specificity of 32% and 39%, respectively, in men and 46% and 51%, respectively, in women after adjustment. Tables of critical voltages for the adjusted criteria and representative performance values are presented. CONCLUSIONS: Incorporation of obesity and age in ECG algorithms consistently improves their performance in the detection of hypertrophy. The development of such criteria will enhance the utility of this inexpensive screening test. Such ECG approaches should be used in clinical trials to assess the efficacy of antihypertensive treatment to effect regression of left ventricular hypertrophy. A search for further improvements in the efficacy of ECG criteria for this purpose is warranted. Independent validation of this approach is needed.

Age Factors↗
PubMed1980

Multidimensional spectroscopic data correlation in the conformation transition of biological macromolecules.

A computerized spectrophotometer system which is capable of simultaneously obtaining three spectral dimensions, that is, the absorbance, the circular dichroism and the fluorescence intensity, from one sample solution has been developed for the purpose of attaining a higher resolving power in the study of conformational transitions of biological macromolecules. Measurement conditions, such as the wavelength, the temperature, pH or the concentration of reagents in the sample solution, can be scanned according to a sequence that is set just prior to the measurement. A computer-driven micro-injector and a pH electrode directly immersed in the sample solution make it possible to obtain a titration curve in parallel to the optical measurement. All the data taken are stored on a magnetic disk for later retrieval. They can be processed and displayed in any required form. The helix-coil transitions of a polynucleotide caused by temperature and those of a polypeptide caused by pH, and the denaturation of proteins caused by guanidine hydrochloride, were studied by this measuring system. The continuous plotting of transition profiles and the correlation diagrams among different spectral dimensions has proved to be a good way of demonstrating the existence of different modes of transition.

Circular Dichroism↗
PubMed1988

Phencyclidine receptors and N-methyl-D-aspartate antagonism: electrophysiologic data correlates with known behaviours.

Using cortical wedges and isolated frog spinal cords, the potency of a series of psychoactive phencyclidine (PCP) and sigma receptor ligands as antagonists of N-methyl-D-aspartate (NMDA) has been compared with their potency in neurochemical and behavioural studies. Phencyclidine receptor, but not sigma or kappa, ligands were selective antagonists of NMDA on both preparations. Combination studies suggested that dissociative anaesthetics and sigma benzomorphans act at the same site. The relative potencies of the drugs as NMDA antagonists correlated well with their potency in PCP receptor binding studies in vitro and in PCP discrimination studies in vivo.

Anesthetics, Dissociative↗