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PubMed2005

Correlation analysis of stenotic aortic valve flow patterns using phase contrast MRI.

Phase contrast MRI is an emerging tool for evaluating valvular pathology. However, the effects of variable image position and valvular pathology on velocity measurements have not been explored. We compare velocity maps with correlation methods, used in image processing to align images and quantify their similarity, to define these effects on calculations of valve orifice area. Quantitative flow images were acquired in four parallel planes (2 in aortic root, 2 in outflow tract), in patients (n = 22) with aortic stenosis. Velocity-time integrals (VTIs) were computed and cross-correlations were performed to quantitatively compare the shapes and relative positions of three-dimensional flow profiles between scans at various positions. Supravalvular VTIs correlated well with one another (R = 0.96), with comparable values. The two subvalvular VTIs exhibited a linear relationship (R = 0.93) but with a 23% difference in mean values. Cross-correlations between supravalvular levels were maximized at (0, 0) offset (indicating concentrically aligned jets) for 19/23 patients, with an average maximum value of 0.957 +/- 0.028; the average for the remainder was 0.800 +/- 0.037. For subvalvular levels, all cross-correlations were maximized at (0, 0) with average maximum 0.968 +/- 0.160. The aortic VTI measurements were comparable, indicating relative insensitivity to the position of the imaging plane; in the LVOT, measurements were only somewhat position-dependent. We conclude that phase contrast MRI is a robust tool for the evaluation of aortic stenosis.

Adult↗

PubMed2004

DTI and impulsivity in schizophrenia: a first voxelwise correlational analysis.

Compromised white matter (WM) integrity in inferior frontal WM has been related to impulsivity in men with schizophrenia. However, these relationships may be more widespread. Fractional anisotropy (FA) derived from diffusion tensor imaging of 25 men with schizophrenia was transformed into Talairach space. Correlations between FA and impulsiveness were examined on a voxelwise basis. We found negative correlations between FA and impulsivity in inferior frontal WM, anterior cingulate, caudate, insula, and inferior parietal lobule. Positive correlations were obtained in the left postcentral gyrus, right superior/middle temporal gyrus, and bilateral fusiform gyrus. These areas may comprise a fronto-temporo-limbic circuit that modulates impulsivity. The voxelwise correlation method can serve as a hypothesis-generation method for relating target behaviors to their underlying neural networks.

Adult↗

PubMed1990

[A genetic correlational analysis of the behavioral and physiological characteristics of spontaneously hypertensive rats (SHR)].

The SHR rats differ from normotensive WKY rats in a number of behavioral and physiological traits. In order to determine causal or accidental nature of relationships between these traits and hypertension, their correlations with arterial pressure level in the 2nd generation of SHR x WKY hybrids (F2), were studied. A positive correlation of body mass and characteristics of potassium appetite with a level of blood pressure corresponding to interstrain differences between SHR and WKY rats was found in F2 population showing genetic connection of these traits with hypertension. The negative correlation in F2 between open-field activity and arterial pressure was opposite to interstrain differences and environmental correlation (within parental strains and F1 hybrids). It seemed to be caused by prevalence of environmental correlation or of accidental fixation of this trait in SHR strain over the genetic connection found in F2 hybrids.

Animals↗

PubMed1992

Auto- and cross-correlation analysis of subthalamic nucleus neuronal activity in neostriatal- and globus pallidal-lesioned rats.

Statistical analyses (autocorrelation and first-order interstimulus interval) were conducted on the spontaneous activity of over 420 subthalamic neurons recorded in 5 groups (control, large globus pallidus kainic acid lesion, partial globus pallidus kainic acid lesion, partial globus pallidus ibotenic acid lesion and neostriatal lesion) of anesthetized rats. Cross-correlation and peristimulus time histogram (to frontal motor cortex stimulation at 0.7 mA) analyses were conducted on pairs (n = 58) of subthalamic neurons recorded simultaneously on a single microelectrode. Lesion of the globus pallidus increased spontaneous firing rate as compared to controls and shifted the pattern of spontaneous activity from either a regular or irregular pattern to a markedly bursting pattern. Neostriatal lesion reduced firing rate and reduced the likelihood of highly regular firing. In control, neostriatal and partial lesioned animals, approximately 1 in 3 pairs of neurons showed correlated firing. The correlations were joint increased probabilities of firing over intervals of 200-400 ms, suggesting a shared excitatory input. No short-interval (less than 10 ms) correlations were seen. Large globus pallidus lesion increased the likelihood of correlated firing (12 of 16 pairs). In all groups of animals the peristimulus time histograms (PSTHs) to motor cortex stimulation were more similar than would be expected by chance and pairs of neurons showed the same increases in response following globus pallidus lesion. Thus adjacent neurons share common cortical inputs and responsiveness to those inputs. These changes indicate that the globus pallidus influences the spontaneous firing rate and pattern of subthalamic neurons as well as the degree of correlated firing of adjacent neurons.

Action Potentials↗

PubMed1988

Evaluation and optimization of the performance of elastic and inelastic scanning transmission electron microscope imaging by correlation analysis.

Scanning Transmission Electron Microscopes (STEM) offer specific characters, such as multidetector configuration, energy loss spectroscopy, external control of the probe raster, which make them quite suited to digital image acquisition and innovative data processing. Considering pixel intensities as random variables, one can apply cross-correlation techniques to pairs of duplicated images. Such methods are used to investigate imaging properties of the instrument, such as the point resolution and the signal to noise ratio, in its different working modes. Concerning the annular dark field, one shows that there exist optimum values for defocus and angle of illumination which minimize the probe size at a value of about 0.5 nm. The same techniques are also used to evaluate the characteristics of energy filtered images recorded in a specific energy window loss around an ionization edge: the degradation in edge resolution with respect to the accompanying ADF images is only of the order of 0.2 to 0.3 nm, which sets the delocalization parameter for an energy loss of 100 eV (i.e. for U-O4-5) well below 1 nm in agreement with theoretical predictions.

DNA↗

PubMed2006

Detection of epidermal growth factor receptor and human epidermal growth factor receptor 2 activating mutations in lung adenocarcinoma by high-resolution melting amplicon analysis: correlation with gene copy number, protein expression, and hormone receptor expression.

Activating mutations in the epidermal growth factor receptor (EGFR) (7p12.3-p12.1) and in the human epidermal growth factor receptor 2 (HER2) (17q21.1) characterize a subset of lung carcinomas. These mutations may relate to the response of the tumor to the tyrosine kinase inhibitors gefitinib and erlotinib. High-resolution melting amplicon analysis is a screening technique that has been shown to be able to detect missense mutations as well as deletions and insertions in tumor DNA isolated from paraffin-embedded tissue sections. In this study, we used high-resolution melting amplicon analysis to screen for EGFR and human HER2 activating mutations in 39 patients with primary lung adenocarcinoma. There were 20 cases that showed bronchioloalveolar histology and 19 cases that did not. The EGFR exons screened were exons 18, 19, 20, and 21, and the HER2 exons screened were exons 19 and 20. Six (15%) of the 39 patients had tumors that contained EGFR activating mutations. Four of the mutations were in adenocarcinomas, which had some bronchioloalveolar features, and 2 mutations were in tumors without bronchioloalveolar features. The EGFR mutations were in exon 19 (2 cases), exon 20 (2 cases), and exon 21 (1 case). One case contained mutations in both exons 18 and 20. One (2.6%) of the 39 patients had a tumor that contained an HER2 activating mutation, and the mutation was located in exon 20. Two of the 6 EGFR mutation-positive cases showed polysomy for chromosome 7, and each one showed overexpression of EGFR as determined by immunohistochemical staining. The other EGFR mutation-positive cases did not show EGFR overexpression and appeared disomic for chromosome 7. The HER2 mutation-positive case was in an adenocarcinoma with bronchioloalveolar features. This tumor did not show overexpression of HER2 and was disomic for chromosome 17. For the non-EGFR mutation-positive cases, 4 (13%) of 32 evaluated cases showed polysomy for chromosome 7 and EGFR. No case showed EGFR gene amplification. Polysomy for chromosome 7 was not related to EGFR overexpression as estimated by immunohistochemistry. Estrogen and progesterone receptor expression was not strong in any of the cases and did not correlate with the presence of EGFR or HER2 mutations.

Adenocarcinoma↗

PubMed1975

[Correlation analysis of indices of toxin-neutralizing activity of sera and antibody titers in the passive hemagglutination reaction].

The authors compared the results of 20 experiments of titration of 1588 sera of children with different vaccination anamnesis by Jensen's method in the passive hemagglutination test with a stable erythrocytic diagnostic agent. In 18 of 20 experiments was established a mean and a high correlational association between the indices of antitoxic diphtheria immunity obtained by two methods. In macro- and micromodifications the passive hemagglutination test proved to be a highly effective method of rapid mass analysis and could be used in epidemiological studies.

Antibodies, Bacterial↗

PubMed1976

Correlation analysis of Baker's studies on enzyme inhibition. 2. Chymotrypsin, trypsin, thymidine phosphorylase, uridine phosphorylase, thymidylate synthetase, cytosine nucleoside deaminase, dihydrofolate reductase, malate dehydrogenase, glutamate dehydrogenase, lactate dehydrogenase, and glyceraldehyde-phosphate dehydrogenase.

The inhibitory activity of 1058 inhibitors of the title enzymes has been formulated in 13 equations correlating chemical structure with inhibitory potency. Two types of regions in enzymes have been defined by means of pi and molar refractivity constants. The use of indicator variables has been extensively developed to suggest special enzyme-ligand interactions. Several examples are given of the use of correlation equations in comparing structural features of different systems.

Animals↗

PubMed1990

Isolation by distance and correlation analysis of distance measures in the study of population structure: example from the Island of Hvar.

Assessment of the population structure on the island of Hvar is based on the analysis of Malécot's isolation by distance model. We have tested the fit of the model by regression analysis of different measures of similarity (genetic kinship) and distance [Hamming's HSM distance for linguistic data; Mahalanobis's D2 distances for anthropometric head and body dimensions, radiogrammetric dimensions of metacarpal bones, physiological (cardiorespiratory) traits, and quantitative dermatoglyphic properties of the digitopalmar complex; and Edwards's E2 for frequencies of erythrocyte antigens]. Good fit of the model for linguistic and anthropometric data, which was demonstrated in previous studies on other eastern Adriatic populations, is confirmed. We compared parameters of the model with those already published for various populations in the eastern Adriatic and other parts of the world. We also evaluated the pattern of correlations between different measures of geographic, biological, and sociocultural distances through principal components analysis and interpreted the results within the context of microevolutionary theory and the population's ethnohistorical background.

Adult↗

PubMed2026

Glutamate metabolic correlation analysis reveals CnP5CS1 contributes to 2-acetyl-1-pyrroline accumulation in aromatic coconut.

Flavor quality, a key sensory attribute of coconut, has consistently been a central breeding objective throughout long-term domestication and varietal improvement efforts. Developing high-aroma varieties requires a clear understanding of their underlying molecular genetic mechanisms. However, research on the metabolic regulatory enzymes involved remains limited, particularly those linked to 2-acetyl-1-pyrroline (2AP), a volatile compound that primarily contributes to the unique scent of aromatic coconuts. We developed contrasting populations and systematically evaluated the role of CnP5CS in 2AP accumulation by examining enzyme activity, metabolic flux, population-level genetic variation, and transcriptional regulatory networks. In the aromatic coconut population, the selected genomic regions were enriched in pathways associated with amino acid metabolism and stress responses. Conspicuously, glutamate (Glu) and its derivatives showed significant correlations within the differentiated populations. The Glu metabolic enzyme P5CS was subjected to strong purifying selection, and haplotype-phenotype association analysis further identified the dominant CnP5CS1 allele genotype. Moreover, we established metabolic marker indicators to assess relative 2AP levels, based on the metabolic profiles of CnP5CS and the substrates and products of its catalyzed reactions. The Y1H assay identified the key transcription factor CnYAB2, which exhibited a strongly correlated expression pattern with CnP5CS1 and major markers of 2AP metabolism. The identification of CnP5CS1 offers a novel perspective on the genetic regulation of 2AP metabolism in aromatic coconuts and establishes a theoretical foundation for developing molecular markers to support the breeding of high-aroma varieties.

Aroma↗

PubMed2006

Annotation of unknown yeast ORFs by correlation analysis of microarray data and extensive literature searches.

Changes in the expression of genes were used to elucidate the metabolic pathways and regulatory mechanisms that respond to environmental or genetic modifications. Results from previously published chemostat datasets were merged with novel data generated in the present study. ORFs displaying significant changes in expression that correlated with those of other ORFs were analysed using GO mapping tools and supplemented by literature information. The strategy developed was used to propose annotations for ORFs of unknown function. The following ORFs were assigned functions as a result of this study: YMR090w, YGL157w, YGR243w, YLR327c, YER121w, YFR017c, YGR067c, YKL187c, YGR236c (SPG1), YMR107w (SPG4), YMR206w, YER067w, YJL103c, YNL175C (NOP13) YJL200C, YDL070C (FMP16) and YGR173W.

Algorithms↗

PubMed2026

A correlation analysis between arsenic and mercury resistance and the spread of antibiotic resistance genes in bacteria isolated from a highly contaminated brownfield.

Seventy-four bacterial strains from El Terronal (Asturias, Spain), a brownfield highly contaminated with mercury and arsenic but without anthropogenic antibiotic influx, were isolated and characterized in culture. No correlation was found between resistance to the aforementioned metal(loid)s and to antibiotics and biocides as tested by agar plates and disk diffusion method, as the number of strains deemed resistant to any of the analyzed antibiotics and biocides was not significantly higher among those with the highest resistance to arsenic and/or mercury. Genome sequencing of 17 of the isolated strains revealed a great number and diversity of antibiotic resistance genes (ARGs), as well as genes related to arsenic and mercury resistance, some of which were located in mobile genetic elements (MGEs). However, most of the detected ARGs were not located in MGEs, and no genes responsible for metal(loid) and antibiotic resistance were found to share an MGE. No evidence was found that resistance to arsenic and mercury influenced the dissemination of ARGs in the studied strains, although the abundance of antibiotic resistance mechanisms related to the presence of RND-type (Resistance-Nodulation-Division) efflux pumps could potentially contribute to cross-resistance.

antibiotics↗

PubMed2003

[Heterosis and genetic correlation analysis of rice (Oryza sativa L.) grain weight development under different environmental conditions].

Two sets of test materials were derived from diallel cross among nine different types of selected rice varieties (lines). Based on the experimental data at different development stages of early and late rice, the estimation of heterosis and genetic correlation of rice grain weight at some development stages (0-->t) or at some special development phases (t--1-->t) was conducted by using additive-dominant genetic model and developmental genetic model for quantitative traits. The results indicated that the heterosis over mid-parent value based on population mean was not significant at 5% level at the early stages (1-12 d), and turned to positively significant as the development process proceeded in early rice. The heterobeltiosis based on population mean appeared to be small negative during the entire courses of grain filling. The heterosis over mid-parent based on population mean appeared to be positively significant at the early and middle grain filling stages (1-18 d), but became insignificant at the late stages (19-28 d) in late rice. The heterobeltiosis based on population mean appeared to be positively significant at the early grain filling stages (1-12 d), but turned to be significantly negative as the development process proceeded in late rice. It also indicated that the heterosis of grain weight development was beneficial to improve the quality of grain filling in late rice, compared to that in early rice. The genetic correlation between the grain weights per se at different stages and the final grain weight was mainly controlled by dominant effects, and became closer with the development process in the early rice, while by additive effects in the late rice. It's suggested that indirect selection of final grain weight throughout the process of grain filling would be more effective in late rice.

Edible Grain↗

PubMed2005

Partial cross-correlation analysis resolves ambiguity in the encoding of multiple movement features.

A classical question in neuroscience is which features of a stimulus or of an action are represented in brain activity. When several features are interdependent either at a given point in time or at distinct points in time, neural activity related to one feature appears to be correlated with other features. Thus techniques that simultaneously consider multiple features cannot account for delayed interdependencies between features. The result is an ambiguity with respect to the encoded features. Here, we resolve this ambiguity by applying a novel statistical method based on partial cross-correlations. The method yields estimates of linear correlations between neural activity and a given feature that are not affected by linear correlations with other features at multiple time delays. The method also provides a graphical output measured on a scale that allows for comparisons between different features, neurons, and experiments. We use real movement data and neural activity simulated according to a wide range of tuning models to illustrate the method. When applied to real neural activity, the procedure yields results that indicate which of the considered features the neural activity is related to and at what time delays.

Action Potentials↗

PubMed1999

Heritability of nociception II. 'Types' of nociception revealed by genetic correlation analysis.

Clinical pain syndromes, and experimental assays of nociception, are differentially affected by manipulations such as drug administration and exposure to environmental stress. This suggests that there are different 'types' of pain. We exploited genetic differences among inbred strains of mice in an attempt to define these primary 'types'; that is, to identify the fundamental parameters of pain processing. Eleven randomly-chosen inbred mouse strains were tested for their basal sensitivity on 12 common measures of nociception. These measures provided for a range of different nociceptive dimensions including noxious stimulus modality, location, duration and etiology, among others. Since individual members of inbred strains are identical at all genetic loci, the observation of correlated strain means in any given pair of nociceptive assays is an index of genetic correlation between these assays, and hence an indication of common physiological mediation. Obtained correlation matrices were subjected to multivariate analyses to identify constellations of nociceptive assays with common genetic mediation. This analysis revealed three major clusters of nociception: (1) baseline thermal nociception, (2) spontaneously-emitted responses to chemical stimuli, and (3) baseline mechanical sensitivity and cutaneous hypersensitivity. Many other nociceptive parameters that might a priori have been considered closely related proved to be genetically divergent.

Animals↗

PubMed1987

Cross-correlation analysis of septohippocampal neurons during theta-rhythm.

The activity from 55 septohippocampal neuron pairs was examined in rats anesthetized with urethane. In addition to the statistical characterization of the firing patterns of the recorded units, the functional interactions between pairs of neurons and between neurons and hippocampal theta (theta) waves were investigated with cross-correlation techniques. Pairs were classified according to the rhythmic or non-rhythmic discharge pattern of their neurons. (a) theta-Pairs were those in which both the medial septal (MS) and hippocampal (HPC) units were rhythmic (type 1 units). (b) Pairs with a rhythmic and a theta-related non-rhythmic unit (type 2 unit) were called mixed pairs. (c) Pairs composed of type 2 units were called type 2 pairs. theta-Pairs showed periodic cross-correlations and frequently fired with a phase difference which could change in different pairs. Mixed pairs also showed periodic cross-correlations although one of the units was non-rhythmic. Type 2 pairs showed non-periodic positive cross-correlations. Our data provide new information regarding the temporal relationship between MS and HPC rhythmic activities supporting the role of the MS in providing the afferent timing for the generation of theta-rhythm in the HPC.

Animals↗

PubMed2005

[A correlate analysis of UV absorption spectra of compound danshen tablets from different manufactures].

OBJECTIVE: To evaluate the value of UV absorption spectrum for identification and quality control of compound Danshen tablets and pills. METHOD: UV absorption spectra of compound Danshen tablets and pills, and other drugs were scanned using ultraviolet spectrophotometer (water as the solvent). Pearson's correlation coefficients (Pearson's R) were displayed in the correlations table obtained from SPSS correlate, and deltaR defined as the absolute value of the difference between Pearson's R and its mirror image in the table were used for measuring the spectral similarity between two drugs from different manufacturers. RESULT: Regarding compound Danshen tablets and pills, the spectral similarity between different batch drugs from same manufacturer was very high with Pearson's R = 0.995-0.9999, and the similarity between two manufactures was high with Pearson's R = 0.92-0.997 and deltaR < 0.02. Compared with the spectra of compound Danshen tablets and pills, the spectral similarity of the other drugs was low with Pearson's R = 0.25-0.98 and deltaR > 0.02. CONCLUSION: The results showed that UV absorption spectrum could be suitable for identification and quality control of compound Danshen tablets and pills.

Drug Combinations↗

PubMed1981

Cross-correlation analysis of the maintained discharge of rabbit retinal ganglion cells.

1. Simultaneous recordings were made from pairs of rabbit retinal ganglion cells. Physiological tests were used to classify the receptive field properties of each cell and the receptive field locations were mapped. 2. The statistical dependence between simultaneously recorded retinal ganglion cells was assessed by cross-correlating the maintained discharge of the simultaneously recorded cells. Cross-correlations from cell pairs in which the constituent cells had non-overlapping receptive field centres were statistically flat, reflecting no statistical dependence. 3. Most cell pairs consisting of transient and sustained concentric cells and having overlapping receptive field centres exhibited a correlated maintained discharge indicative of statistical dependence. The strength of the statistical dependence varied approximately inversely with the degree of overlap between the two cells comprising the cell pair. 4. Cell pairs consisting of two ON-centre cells or two OFF-centre cells and having overlapping receptive field centres possessed incremental cross-correlations which were characterized by a peak centred near zero. Cell pairs consisting of an ON-centre cell with an OFF-centre and having overlapping receptive field centres possessed decremental cross-correlations which were characterized by a valley centred near zero. 5. The results are consistent with the hypothesis that a noise source provides shared input to two or more retinal ganglion cells. Bipolar and photoreceptors are the most likely sources of noise responsible for the statistical dependency between retinal ganglion cells.

Action Potentials↗