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PubMedDate not supplied

[Morphological data correlated with the mechanism of striated muscle contraction].

The classical theory of muscle contraction (Huxley, 1957) could not entirely explain a series of theoretical and experimental data. This theory sustains a longitudinal sliding of thin filaments on thick ones, by the tilting of myosin cross-bridges. Under different stimuli inducing contractions, the stereospecific conformations of cross-bridges appear to be different as it is shown using electron microscopy, fluorescence polarization, electron paramagnetic resonance (EPR) spectroscopy and equatorial X-ray diffraction. Our optic microscopy data also suggest the existence of such conformations, induced by different contractile stimuli.

Animals↗
PubMed2004

Efficient computation of significance levels for multiple associations in large studies of correlated data, including genomewide association studies.

Large exploratory studies, including candidate-gene-association testing, genomewide linkage-disequilibrium scans, and array-expression experiments, are becoming increasingly common. A serious problem for such studies is that statistical power is compromised by the need to control the false-positive rate for a large family of tests. Because multiple true associations are anticipated, methods have been proposed that combine evidence from the most significant tests, as a more powerful alternative to individually adjusted tests. The practical application of these methods is currently limited by a reliance on permutation testing to account for the correlated nature of single-nucleotide polymorphism (SNP)-association data. On a genomewide scale, this is both very time-consuming and impractical for repeated explorations with standard marker panels. Here, we alleviate these problems by fitting analytic distributions to the empirical distribution of combined evidence. We fit extreme-value distributions for fixed lengths of combined evidence and a beta distribution for the most significant length. An initial phase of permutation sampling is required to fit these distributions, but it can be completed more quickly than a simple permutation test and need be done only once for each panel of tests, after which the fitted parameters give a reusable calibration of the panel. Our approach is also a more efficient alternative to a standard permutation test. We demonstrate the accuracy of our approach and compare its efficiency with that of permutation tests on genomewide SNP data released by the International HapMap Consortium. The estimation of analytic distributions for combined evidence will allow these powerful methods to be applied more widely in large exploratory studies.

Association↗
PubMedDate not supplied

In vitro chemopreventive efficacy screening using human keratinocytes and the in vivo data correlation.

Agents with potential cancer preventive activity were screened for efficacy in the Human Epidermal Cell (HEC) Assay. The HEC Assay measures inhibition of propane sultone-induced changes in the growth and/or differentiation in early passage keratinocyte cultures. The assay biomarkers were calcium tolerance, growth inhibition, and involucrin induction. The HEC Assay also provides information on the cytotoxicity of the agents following acute and chronic exposure. Agents were evaluated at non-toxic doses in the HEC Assay. The HEC Assay has been used to screen twenty-eight agents for chemopreventive efficacy. A positive response in one or more endpoints of the HEC Assay correlates 100% (16/16) with a positive response in one or more of the animal cancer prevention models (J. Cell. Biochem., 26S:29-53, 1996). The overall sensitivity for predicting efficacy in animals is 84%. The available data suggest that a positive assay response appears to be highly predictive of efficacy in vivo.

Animals↗
PubMed2000

The variability of serial fMRI data: correlation between a visual and a motor task.

We investigated whether the intersession variability of serial fMRI studies correlates between two activation modalities, i.e. a standardized visual and a standardized motor task. Six volunteers were scanned in at least weekly intervals. The number of pixels activated as well as the activation amplitude varied widely. The maximal difference of the number of pixels activated was 1150%, of the activation amplitude 250%. In three volunteers, the variability was highly correlated between the two tasks. Three other volunteers showed one outlier each. We conclude that the intersession variability is due to global factors affecting the whole brain, but that due to unpredictable outliers, using a standardized task to normalize the data of interest is of limited value.

Adult↗
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↗
PubMed2002

[Are age and urodynamic data correlated in women with stress urinary incontinence (SUI)?].

PURPOSE: Our aim was to evaluate the impact of age on lower urinary tract function in women by means of urodynamics and modelized analysis of the recorded free uroflow curves. MATERIAL AND METHODS: One hundred and fifty three women (age range: [30-93 years]; 6 decades A to F) with only SUI complaint underwent a urodynamic evaluation which included initial free uroflow, urethral pressure profile, cystometry and final free uroflow at bladder functional capacity. Modelized analysis was performed using the VBN mathematical micturition model; from comparison between recorded and computerized theoretical flow curves this model allows to determine two characteristic parameters: one of urethral obstruction and one of detrusor efficiency. RESULTS: No age-related changes were found in bladder capacity, peak flow rate in the first void and post residual volume. A significant increase of peak flow rate was noted in the second void for D and older. Bladder compliance decreased only from E. As usually described a decrease with age of the maximum urethral closure pressure occurred while the functional urethral length decreased only from E. A flat distribution of the VBN parameters was observed. DISCUSSION-CONCLUSION: This study shows the absence of age-associated changes in both urodynamic data and VBN parameters in a population of women with SUI and without any other disease. These findings reinforce the idea that chronological age does not strongly correlate with the physiological status.

Adult↗
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↗
PubMed1992

Application of magnetic resonance imaging to the measurement of neurodegeneration in rat brain: MRI data correlate strongly with histology and enzymatic analysis.

Focal brain ischemia was induced by middle cerebral artery occlusion in the rat. The volume of cerebral damage was determined 2 days later by MRI in vivo and in the same animals histologically. The edema volume as measured by MRI and the histologically determined infarction was highly correlated. As a consequence, the neuroprotective effect of the N-methyl-D-aspartate (NMDA) receptor antagonists CGP 40116 and MK 801 were similar with both methods. Excitotoxic neurodegeneration in the rat striatum was induced by direct injection of quinolinic acid. The degree of damage was evaluated in vivo 1 day later by quantitative MRI, and 7 days later by measuring the activities of neuronal marker enzymes choline acetyltransferase and glutamic acid decarboxylase. Striatal damage assessed using the three approaches was highly correlated. Cerebroprotective efficacy of the NMDA receptor antagonist CGP 40116 was indistinguishable based on all methods. MRI was more reproducible than the enzymatic methods and was faster and simpler than histologic examination for routine analysis of excitotoxic damage and cerebroprotection in vivo in a pharmaceutical research environment.

2-Amino-5-phosphonovalerate↗
PubMed2006

Binding of different monosaccharides by lectin PA-IIL from Pseudomonas aeruginosa: thermodynamics data correlated with X-ray structures.

The lectin from Pseudomonas aeruginosa (PA-IIL) is involved in host recognition and biofilm formation. Lectin not only displays an unusually high affinity for fucose but also binds to L-fucose, L-galactose and D-arabinose that differ only by the group at position 5 of the sugar ring. Isothermal calorimetry experiments provided precise determination of affinity for the three methyl-glycosides and revealed a large enthalpy contribution. The crystal structures of the complexes of PA-IIL with L-galactose and Met-beta-D-arabinoside have been determined and compared with the PA-IIL/fucose complex described previously. A combination of the structures and thermodynamics provided clues for the role of the hydrophobic group in affinity.

Adhesins, Bacterial↗