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At least 163 records · Page 9Linked to original sources

PubMed1990

Growth related increase in rat intervertebral disc size: a quantitative radiographic and histologic comparison.

Methods were developed for measuring the width of lumbar intervertebral discs in Sprague-Dawley rats. Rates of growth of the L4-5 and L5-6 discs in a rostral-caudal direction in an approximately midsagittal plane were reported from analysis of radiographic and histologic data. The radiographic data correlated with histologic data (p less than 0.001). It was concluded that the L4-5 and L5-6 intervertebral discs continue to increase in size throughout the first 18 months of life of the rat, well past the age of rapid gain in body weight.

Animals↗

PubMed1986

Inexpensive stereoscopic CCRG camera for lens/cataract photography in vitro.

In 1978 the American Cooperative Cataract Research Group (CCRG) adopted a stereoscopic camera system for photographing human cataracts in vitro based upon a Zeiss OPMI 1 operating microscope (Carl Zeiss, Inc.; Oberkochen, West Germany). Photographs obtained with this system were used to classify human cataractous change according to the standardized CCRG protocol. Classification data correlated with laboratory data furthered the attempt to define the biochemical or biophysical basis for specific types of cataractous change. Presently, the high cost of this camera (exceeding $20,000) precludes its use by many laboratories wishing to do human lens research. This study describes an inexpensive (less than $2,200) alternative camera for this type of photography. Adjacent frames on the film strip constitute stereo pairs which can be viewed in a modified stereo viewer. In the original CCRG camera both members of a stereo pair were included in the same frame. The quality of the stereo images obtained with this new system nearly equals that with the original Zeiss system. It is hoped that this inexpensive system will allow more scientists to participate in CCRG-related research and increase the supply of intracapsularly extracted cataracts available to all collaborating CCRG scientists.

Cataract↗

PubMed2004

Anxiety sensitivity as a predictor of panic attacks.

Anxiety sensitivity (AS) is the fear of physical symptoms of anxiety and related sensations believed to have harmful consequences. AS may play a central role in the nature and etiology of panic disorder (PD) and the genesis of panic attacks. We collected Anxiety Sensitivity Index (ASI) scores from PD patients and controls to determine if AS accurately predicts panic. ASIs were completed prior to panic induction using the modified Read rebreathing test in both hypoxic and hyperoxic conditions. Total scores first-order factors, and individual item ASI scores were correlated with panic presence (Spearman correlation) for each of the hypoxic and hyperoxic rebreathing tests for both study populations. Control subjects' data correlated significantly for items 4, 8, and 11 of the ASI for the hyperoxic (n=9; r(S)=0.63, 0.70, and 0.63, respectively) and items 4 and 8 for the hypoxic rebreathing tests (n = 9; r(S) = 0.63 and 0.70, respectively). Panic patients' data correlated significantly for item 1 of the ASI for hyperoxic tests (n=8; r(S)=0.76) and item 5 for the hypoxic tests (n = 8; r(S) = 0.95). Total ASI scores or first-order factors (physical, social concerns, and mental incapacitation) scores of either study group did not correlate significantly with panic presence. AS may not be a reliable predictor of panicogenic responses to CO2-induced panic in either PD or normal control populations. AS may not be an ultimate causal element in eliciting panic attacks.

Adult↗

PubMed1986

[Correlation between quantitative indicators of the bioelectrical activity of the heart atria and central hemodynamics in patients with ischemic heart disease based on correlation analysis data].

Atrial bioelectrical activity (according to large-scale ECG findings) and central hemodynamics were studied in 43 coronary patients. A correlation analysis showed an increased correlation between the studied values in patients with diffuse and postinfarctional cardiosclerosis and those in healthy subjects. The authors stressed the most significant large-scale ECG values. A conclusion was made of the appropriateness of a study of atrial bioelectrical activity by the method of large-scale electrocardiography and hemodynamics for diagnostics in coronary patients with the initial stage of cardiac insufficiency.

Adult↗

PubMed2003

Evaluation of rat intestinal absorption data and correlation with human intestinal absorption.

The absorption of 111 drug and drug-like compounds was evaluated from 111 references based on the ratio of urinary excretion of drugs following oral and intravenous administration to intact rats and biliary excretion of bile duct-cannulated rats. Ninety-eight drug compounds for which both human and rat absorption data were available were selected for correlation analysis between the human and rat absorption. The result shows that the extent of absorption in these two species is similar. For 94% of the drugs the absorption difference between humans and rats is less than 20% and for 98% of drugs the difference is less than 30%. There is only one drug for which human absorption is significantly different from rat absorption. The standard deviation is 11% between human and rat absorption. The linear relationship between human and rat absorption forced through the origin, as determined by least squares regression, is %Absorption (human)=0.997%Absorption (rat) (n=98, SD=11). It is suggested that the absorption in rats could be used as an alternative method to human absorption in pre-clinical oral absorption studies.

Algorithms↗

PubMed1995

Upper extremity performance test for the elderly (TEMPA): normative data and correlates with sensorimotor parameters. Test d'Evaluation des Membres Supérieurs de Personnes Agées.

OBJECTIVES: Objectives of this study were to develop normative data for the Test d'Evaluation des Membres Supérieurs de Personnes Agées (TEMPA) and determine its relation to upper extremity sensorimotor parameters such as fine and gross dexterity, coordination, strength, endurance, range of motion, and several types of sensibility. DESIGN: Cross-sectional study. SETTING: Community-dwelling subjects. PARTICIPANTS: Three hundred sixty healthy subjects randomly recruited by age and sex strata (60 to 69, 70 to 79, and 80 or older). MAIN OUTCOME MEASURES: Length of execution of the tasks in the TEMPA. RESULTS: Normative data are reported by gender and age group. The time taken to execute the tasks increased significantly with age. The women were faster on the tasks requiring a higher degree of fine dexterity, whereas the task requiring a lesser degree of fine dexterity and sensibility and more grip strength was accomplished faster by the men. Subjects who were more active and described themselves as being in excellent or good health performed better. CONCLUSION: The norms will help clinicians differentiate better between normal and pathological aging in upper extremity performance.

Aged↗

PubMed2003

Normalization of DNA-microarray data by nonlinear correlation maximization.

Signal data from DNA-microarray ("chip") technology can be noisy; i.e., the signal variation of one gene on a series of repetitive chips can be substantial. It is becoming more and more recognized that a sufficient number of chip replicates has to be made in order to separate correct from incorrect signals. To reduce the systematic fraction of the noise deriving from pipetting errors, from different treatment of chips during hybridization, and from chip-to-chip manufacturing variability, normalization schemes are employed. We present here an iterative nonparametric nonlinear normalization scheme called simultaneous alternating conditional expectation (sACE), which is designed to maximize correlation between chip repeats in all-chip-against-all space. We tested sACE on 28 experiments with 158 Affymetrix one-color chips. The procedure should be equally applicable to other DNA-microarray technologies, e.g., two-color chips. We show that the reduction of noise compared to a simple normalization scheme like the widely used linear global normalization leads to fewer false-positive calls, i.e., to fewer genes which have to be laboriously confirmed by independent methods such as TaqMan or quantitative PCR.

Algorithms↗

PubMed1964

HOME MOVIES OF EARLY CHILDHOOD: CORRELATIVE DEVELOPMENTAL DATA IN THE PSYCHOANALYSIS OF ADULTS.

During the course of psychoanalytic practice, it has been possible to review with specific patients sequential films taken by their parents, beginning with the earliest weeks of infancy. The photographic evidence, combined with the patient's accompanying verbal associations, sheds additional light on evolving behavioral patterns such as affective expression, communication with others, and motility and its mastery, as well as early social interactions, and serves to correlate with reconstructions made, from psychoanalytic data.

Adult↗

PubMed1998

Analysis of clustered data in receiver operating characteristic studies.

Clustered data is not simply correlated data, but has its own unique aspects. In this paper, various methods for correlated receiver operating characteristic (ROC) curve data that have been extended specifically to clustered data are reviewed. For those methods that have not yet been extended, suggestions for their application to clustered ROC studies are provided. Various methods with respect to their ability to meet either of two objectives of the analysis of clustered ROC data are compared to consider a variety of ROC indices and their accessibility to researchers. The available statistical methods for clustered data vary in the range of indices that can be considered and in their accessibility to researchers. Parametric models permit all indices to be considered but, owing to computational complexity, are the least accessible of available methods. Nonparametric methods are much more accessible, but only permit estimation and inference about ROC curve area. The jackknife method is the most accessible and permits any index to be considered. Future development of methods for clustered ROC studies should consider the continuation ratio model, which will permit the application of widely available software for the analysis of mixed generalized linear models. Another area of development should be in the adoption of bootstrapping methods to clustered ROC data.

Bayes Theorem↗

PubMed2006

Improved strategy for mononuclear cell collection for donor lymphocyte infusions.

BACKGROUND: To improve donor management for donor lymphocyte collections, a protocol was established to tailor the amount of whole blood processed during leukapheresis to achieve the requested cellular dose. STUDY DESIGN AND METHODS: A retrospective review of donor and product records of all donors who provided donor lymphocytes during the period October 27, 1999, to March 2, 2005, was performed (25 donors, 54 collections). Data on product total CD3+ T cells collected and total blood volume (TBV) processed were used to establish a correlation between the two variables. The resultant correlation from the reference group (8 donors, 13 collections) was then used to prospectively determine the TBV to be processed in a subsequent series of collections ("prospective group": 18 donors, 41 collections). Donor charts were also reviewed to determine leukapheresis-associated adverse events. RESULTS: The application of the correlation data between TBV processed and CD3+ T-cell yields from the initial reference group to the prospective group yielded 92 percent successful collections; in 3 of the 4 inadequate collections, the predefined maximum of three times their TBV was processed. Compared to the reference group, the TBV processed in the prospective group was decreased from 12,598+/-4007 to 7942+/-5079 mL; the length of procedure was decreased from 208+/-53 to 146+/-79 minutes. Adverse event data were reviewed for 51 collections; the percentage of procedures without adverse events increased from 23 percent in the reference group to 37 percent in the prospective group. CONCLUSION: Application of correlation data between TBV processed and CD3+ T-cell yield was useful to predict efficient and successful donor lymphocyte collections.

Blood Volume↗

PubMed1996

A mixed effects model for multivariate ordinal response data including correlated discrete failure times with ordinal responses.

The mixed effects model for binary responses due to Conaway (1990, A Random Effects Model for Binary Data) is extended to accommodate ordinal responses in general and discrete time survival data with ordinal responses in particular. Given a multinomial likelihood, cumulative complementary log-log link function, and log-gamma random effects distribution, the resulting marginal likelihood has a closed form. As a result, a Newton-Raphson estimation procedure is feasible without resorting to numerical, approximation-based, or Monte Carlo integration techniques. The parameters in the model have a proportional hazards interpretation in terms of multivariate discrete time data with ordinal responses. Using data from a psychological example, the proposed method is compared with other mixed effects approaches as well as population-averaged models.

Biometry↗

PubMed1993

Rapid access to pharmacokinetics data and correlation between antimicrobial susceptibility results and drug tissue distribution using a personal computer.

MYMIC is a computer-aided system capable of integrating antibiotic susceptibility data with the concentrations the drugs reach in various body tissues and fluids by calculating site concentration/minimal inhibitory concentration quotients. The program can be run on any low-cost personal computer operating under MS-DOS, provided it is equipped with a hard-disk drive and with a minimum of 512 kilobytes of random access memory. The use of the program does not require any knowledge of computer languages. The antibiotic susceptibility data can be entered either as minimal inhibitory concentrations or as inhibitory zone diameters; in the latter case, minimal inhibitory concentrations are automatically calculated via regression formulas. The concentrations obtained by 90 antibiotics in 51 different human tissues and fluids are recorded in a data base of over 1,000 records, obtained from roughly 700 original papers. A MYMIC sample session was simulated by mimicking infections of three different body districts (namely bone, prostate, and sputum) caused by Pseudomonas aeruginosa, Escherichia coli or Providencia stuartii.

Anti-Bacterial Agents↗

PubMed2007

Bivariate random effect model using skew-normal distribution with application to HIV-RNA.

Correlated data arise in a longitudinal studies from epidemiological and clinical research. Random effects models are commonly used to model correlated data. Mostly in the longitudinal data setting we assume that the random effects and within subject errors are normally distributed. However, the normality assumption may not always give robust results, particularly if the data exhibit skewness. In this paper, we develop a Bayesian approach to bivariate mixed model and relax the normality assumption by using a multivariate skew-normal distribution. Specifically, we compare various potential models and illustrate the procedure using a real data set from HIV study.

Bayes Theorem↗

PubMed1993

The sequence-immunology correlation revisited: data for cetacean myoglobins and mammalian lysozymes.

Quantitative microcomplement fixation tests employing rabbit antisera were done to compare immunologically 13 cetacean myoglobins and 15 mammalian lysozymes c of known amino acid sequence. In both cases there was a strong correlation between immunological distance (y) and percent sequence difference (x), as had been found for several other globular proteins. For myoglobin the relationship could be described by y = 10.5x and for lysozyme by y = 8.5x. The coefficients in both of these equations are appreciably higher than the values of 5.1-6.9 reported for three other vertebrate globular proteins (bird lysozyme c, mammalian ribonuclease, and mammalian serum albumin), and they imply that rabbit antisera to mammalian myoglobins and lysozymes are more sensitive to evolutionary substitutions. A strong inverse correlation (r = -0.95) was found when the slope of the line relating y to x for these five data sets was plotted against the percent sequence difference between the rabbit's own protein and the proteins immunized with. Specifically, the cetacean myoglobins on average differ in amino acid sequence from rabbit myoglobin by less than 13% and exhibit the steepest slope (10.5), while bird lysozyme sequences differ by nearly 40% from rabbit lysozyme and exhibit the shallowest slope (5.1).

Amino Acid Sequence↗

PubMed1989

[Quantitative analysis of the lung CT in normal subjects and in patients with noncardiac pulmonary edema].

A quantitative analysis was performed of the CT images relative to 7 normal human subjects and to 22 patients affected with ARF (Acute Respiratory Failure). The CT scanner image quality was investigated, and the unit was checked with quality control procedures, in order to assure reliability and reproducibility. In every patient the lung was scanned at 3 different levels--basis, hilum and apex. The frequency distribution of CT numbers was studied. The lung areas were calculated for the different conditions, and the data correlated with functional lung data. A method was then tested to evaluate lung weight; the data obtained did not differ from literature data. All the patients were treated with different positive and expiratory pressure (PEEP). For different PEEP values, the quantitative data from CT analysis were correlated with morphofunctional indices.

Adult↗

PubMed1990

Analyzing correlated binary data using SAS.

We discuss methods for analyzing repeated binary measurements on the same individual. In spite of the fact that the repeated measurements on the same individual are correlated, the ordinary logistic regression maximum likelihood estimates (which assume that the repeated measures are independent) are consistent and asymptotically normal (K. Y. Liang and S. L. Zeger, Biometrika 73, 13 (1986]. However, the inverse of the estimated information matrix (assuming independence) can give inconsistent estimates of the asymptotic variance of estimated parameters. We describe how to obtain the logistic regression estimates, as well as a consistent estimate of their covariance matrix, in SAS, with minimal matrix manipulations.

Analysis of Variance↗

PubMed2003

Morphological quantification of emphysema in small human lung specimens: comparison of methods and relation with clinical data.

Small human lung specimens are frequently used for cell biological studies of the pathogenesis of emphysema. In general, lung function and other clinical parameters are used to establish the presence and severity of emphysema/chronic obstructive pulmonary disease without morphological analysis of the specimens under investigation. In this study we compared three morphological methods to analyze emphysema, and evaluated whether clinical data correlate with the morphological data of individual lung samples. A total of 306 lung specimens from resected lung(lobes) from 221 patients were inflated and characterized using three morphological parameters: the Destructive Index, the Mean Linear Intercept, and Section Assessment. Morphological data were related to each other, to lung function data, and to smoking behavior. Significant correlations (P < .001) were observed between Section Assessment and Destructive Index (r = 0.92), Mean Linear Intercept with Destructive Index (r = 0.69) and Mean Linear Intercept with Section Assessment (r = 0.65). Section Assessment, being much less time consuming than Mean Linear Intercept and Destructive Index, is the parameter of choice for initial analysis. Destructive Index is the most sensitive parameter. There was a significant (P < .001), but weak correlation for all three parameters with the diffusion capacity for CO (K(CO)) (Destructive Index: r = -0.28; Mean Linear Intercept: r = -0.34; Section Assessment: r = -0.32), and with FEV(1)/IVC (Destructive Index: r = -0.29; Mean Linear Intercept: r = -0.33; Section Assessment: r = -0.28), but not with other lung function parameters. A significant difference (P < .05) between (ex-) smokers and never-smokers was observed for Destructive Index and Section Assessment. It is concluded that the application of the three morphological parameters represents a useful method to characterize emphysematous lesions in a (semi-)quantitative manner in small human lung specimens, and that Section Assessment is a suitable and fast method for initial screening. The extent of emphysema of individual lung specimens should be established by means of morphometry, rather than lung function data.

Adult↗

PubMed1999

Inferring causality from relational data and designs: historical and contemporary lessons for research and clinical practice.

My address to you today is born of frustration with the growing claims, evident in the research literature and in clinical reports that happen to cross my desk, of causation made on the basis of correlational data. I recall, as a sophomore in college, being taught early in my first experimental psychology course, "you cannot infer causality from correlation." This point was made adamant in my first face-to-face critique of an experimental psychology research paper by Dr. Robert T. Brown, who pointed out, in lowering my grade, that I had inferred organic causes to behavior patterns in gerbils based solely on correlational data. This caution was reiterated in my statistics courses until it must have been indelibly stamped upon my then still somewhat plastic brain.

Analysis of Variance↗