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Results for “Correlation analysis”

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PubMedDate not supplied

Microdensitometer-computer correlation analysis of two distinct, spatially segregated classes of microtubule bridges in Allogromia pseudopodia.

Previous video-light microscopic studies have shown that the microtubule bundles in the pseudopodia of foraminiferan protists display several types of movements in vivo, including active bending, zipping/splaying, and axial translocations. To gain insight into the types and arrangement of microtubule-associated proteins (e.g., mechanoenzymes, crosslinkers) in such a highly dynamic system, we employed microdensitometric-computer correlation methods to analyze, quantitatively, intermicrotubule bridges in thin-section electron micrographs of Allogromia laticollaris and Allogromia sp. (strain NF). Two distinct bridges occupying mutually exclusive zones between adjacent microtubules were identified. Type I bridges displayed a single axial repeat (34 nm for A. laticollaris and 28 nm for Allogromia sp.) and Type II bridges showed a typical 12-dimer helical superlattice pattern. In A. laticollaris, the two types of bridges were morphologically distinct: Type I bridges were aligned perpendicular to the microtubule wall and were 23-nm wide with an electron-lucent core; Type II bridges were irregular filaments projecting from the microtubules at various angles. When compared with the known distribution of microtubule-associated proteins in other systems, our findings indicate that, in vivo, Allogromia pseudopodial microtubules are decorated with MAP2-like bridges interrupted by discrete clusters of a dynein-like component.

Animals↗

PubMed1987

Assessment of fear in adult laying hens: correlational analysis of methods and measures.

The fear responses of adult laying hens of two lines, flighty and docile, were assessed in each of three commonly employed and widely differing test situations. These were the pen with cone, novel rod and tonic immobility tests. Each hen was ranked for fearfulness on each behaviour pattern recorded and was then assigned an overall 'fear rank' in each of the three tests. Significant intra-individual correlations were found in both lines between the ranked responses within tests and between the overall fear ranks assigned in each of the three test situations. The findings support the use of these tests as methods of assessing fear in adult laying hens and are considered to reflect the estimation of general underlying states of fear rather than stimulus-specific responses.

Animals↗

PubMed1989

Pattern-reversal visual evoked potentials in normal 7- to 15-year-old twins: a correlation analysis.

Pattern-reversal visual evoked potentials (PRVEPs) were tested in 11 sets of monozygotic (MZ) twins and 22 sets of dizygotic (DZ) twins matched on age, sex and educational level. They ranged in age from 7 to 15 years. The PRVEPs of MZ twins exhibited a significantly greater degree of similarity than those of DZ twins. The peak latencies and amplitudes of PRVEP components obtained from MZ twin pairs were significantly correlated. The correlation coefficients for the peak latencies of the P2 (or P100) component were the only ones to differ significantly between the DZ twins of the same sex and DZ twins of opposite sexes. These coefficients, obtained using PRVEPs, were much greater than those obtained with flash visual evoked potentials.

Adolescent↗

PubMed1997

[Correlative analysis with proliferating cell nuclear antigen,bromodeoxyuridine,and microscopic observation on golden hamster carcinogenesis model]

The early diagnosis of carcinomatous conversion has special significance on increasing effectiveness.Proliferating cell nuclear antigen(PCNA),bromodeoxyuridine(BRDU)(immunohistochemistry ways),and microscopic diagnosis were applied and observed on golden hamster cheek pouch carcinogenisis model induced by dimethybenzanthracene(DMBA) in order to seek simple,effective,leading and reliable diagnostic way.The results showed that three observable means had significant correlation,and demonstrated that immunohistochemistry ways practical value in diagnosis of carcinomatous conversion.This study suggests that PCNA and BRDU are more sensitive,simple and reliable,and two hopeful methods of early diagnosis of carcinomatous conversion.

Journal Article↗

PubMedDate not supplied

No parallel fiber volleys in the cerebellar cortex: evidence from cross-correlation analysis between Purkinje cells in a computer model and in recordings from anesthetized rats.

Purkinje cells aligned on the medio-lateral axis share a large proportion of their approximately 175,000 parallel fiber inputs. This arrangement has led to the hypothesis that movement timing is coded in the cerebellum by beams of synchronously active parallel fibers. In computer simulations I show that such synchronous activation leads to a narrow spike cross-correlation between pairs of Purkinje cells. This peak was completely absent when shared parallel fiber input was active in an asynchronous mode. To determine the presence of synchronous parallel fiber beams in vivo I recorded from pairs of Purkinje cells in crus IIa of anesthetized rats. I found a complete absence of precise spike synchronization, even when both cells were strongly modulated in their spike rate by trains of air-puff stimuli to the face. These results indicate that Purkinje cell spiking is not controlled by volleys of synchronous parallel fiber inputs in the conditions examined. Instead, the data support a model by which granule cells primarily control Purkinje cell spiking via dynamic population rate changes.

Action Potentials↗

PubMed2002

Full identification of a linear-nonlinear system via cross-correlation analysis.

A statistical model used extensively in vision research consists of a cascade of a linear operator followed by a static (memoryless) nonlinearity. Common applications include the measurement of simple-cell receptive fields in primary visual cortex and the modeling of human performance in various psychophysical tasks. It is well known that the front-end linear filter of the model can readily be recovered, up to a multiplicative constant, using reverse-correlation techniques. However, a full identification of the model also requires an estimation of the output nonlinearity. Here, we show that for a large class of static nonlinearities, one can obtain analytical expressions for the estimates. The technique works with both Gaussian and binary noise stimuli. The applicability of the method in physiology and psychophysics is demonstrated. Finally, the proposed technique is shown to converge much faster than the currently used linear-reconstruction method.

Humans↗

PubMed1982

Cross-correlation analysis of interneuronal connectivity in the motor cortex of the monkey.

Pairs of neurones were recorded within the hand region of the precentral motor cortex of monkeys trained to squeeze a force transducer between the thumb and index finger. Neuronal discharges of a pair of cells, recorded through the same electrode, were first examined for their co-variation with force. The discharges of those pairs with a consistent co-variation were cross-correlated during periods of constant isometric force. Cross-correlograms in the majority of cases had either a sharp peak or trough at latencies suggesting monosynaptic causal relations between the cell discharges. A peak was associated with pairs of cells whose discharges co-varied similarly with force and when a trough was observed, the cell discharges of the pair generally differed in their force co-variation. It is concluded that the action of motor cortical neurones is linked by common and recurrent collateral inputs during isometric co-contraction of finger muscles.

Action Potentials↗

PubMed1995

[Correlation analysis between patlak plot and DAR using 11C-methionine PET].

Seven patients were studied with positron emission tomography (PET) using 11C-methionine. All had non-Hodgkin's lymphoma but one, who had Hodgkin's disease. By assuming a simple three-compartment model for dynamic data analysis, we used the graphic method proposed by Patlak et al., where Ki (K2K3/(K1+K3)) was compared with DAR (differential absorption ratio). Trichloroacetate was added to each plasma sample, and the activity of the acid-soluble fraction was counted to eliminate the influence of the protein-bound fraction of injected activity. Patlak data plots, using this acid-soluble fraction as an input factor, showed good linearity over the time of data collection. All tumors showed clear 11C-methionine accumulation. Tumor activity reached almost a plateau within 10 min and was kept at the same level for at least 30 min. Ki and DAR were 0.070 +/- 0.035 and 4.64 +/- 1.85 (mean +/- SD), respectively. There was no apparent correlation between histological type and Ki or DAR, while the correlation efficient between Ki and DAR was 0.875. Our conclusion is that DAR will give almost the same result as dynamic data in the analysis of methionine metabolism using PET.

Aged↗

PubMed1992

A canonical correlation analysis of the influence of neuroticism and extraversion on chronic pain, suffering, and pain behavior.

The relationship between neuroticism and extraversion on the 4 major stages of pain processing, that of pain sensation intensity, pain unpleasantness, suffering, and pain behavior, were studied in 205 chronic pain patients (88 male and 117 female). Patients underwent psychological evaluation which included the Pain Experience visual analogue scales (VAS) (Price et al. 1983), NEO Personality Inventory (NEO-PI) (Costa and McCrae 1985), and the Psychosocial Pain Inventory (PPI) (Getto and Heaton 1980). Canonical correlation was used to control for pain sensation intensity in evaluating affective dimensions of pain and to control for neuroticism in assessing effects of extraversion on different stages and dimensions of pain. Neither neuroticism nor extraversion were related to pain sensation intensity. Only neuroticism was associated with pain unpleasantness. Personality factors had their greatest impact on stages 3 (suffering) and 4 (illness behavior) of pain processing. The results of multiple regression analyses indicated that life-long vulnerability to anxiety and depression is paramount in understanding the relationship between personality and suffering in chronic pain. These findings provide support for the idea that personality traits influence the ways in which people cognitively process the meanings that chronic pain holds for their life, and hence the extent to which they suffer.

Adult↗

PubMed2004

Plasma concentrations of anxiolytic neurosteroids in men with normal anxiety scores: a correlation analysis.

Neurosteroids are physiological regulators of anxiety in experimental animals, but there are no data for humans about the modulatory effects of the hormones on normal aspects of this emotional parameter. Plasma concentrations of four neurosteroids, pregnenolone, progesterone (PROG), allopregnanolone and tetrahydrodeoxycorticosterone, suggested to be major anxiety regulators in experimental animals, were measured in a group of 58 physically and psychologically normal adult male subjects. In parallel, trait (genotypical) and state (phenotypical) anxiety scores were measured by the State-Trait Anxiety Inventory. The possible correlations between the hormonal secretions and the psychological parameters were statistically analyzed. The neurosteroid concentrations and the anxiety scores of the probands were within the ranges of normality according to data of the literature and our own. PROG concentrations correlated significantly with state anxiety scores. These data suggest that neurosteroids may physiologically modulate anxiety not only in experimental animals but also in humans.

Adult↗

PubMed1996

[The correlational analysis assessment of exacerbation in bronchial asthma and treatment efficacy].

Blood and sputum eosinophils, eosinophilic cation protein (ECP) in the serum and OPV1 were measured in 30 patients with atopic bronchial asthma (BA) of moderate severity showing eosinophilia at the beginning and the end of treatment week 1 and 4, respectively. In exacerbation of BA relative number of blood eosinophils averaged 10.4 + -1.4%, sputum 35.2 + -5.6%. Serum concentration of ECP, OPV1, IgE averaged 42.6% + -11.9%, 66.8 + -6.3%, 753.7 + -114 IU/ml, respectively. In exacerbation a strong correlation is noted between relative number of eosinophils in the blood and sputum, between the levels of IgE and ECP. At the end of the treatment OPV1 was higher while ECP level in the serum went down. Reduced eosinophilia in the blood and sputum correlated with OPV1 increment. In BA patients with high blood and sputum eosinophilia function of the lungs depends on eosinophilic number, while in normalization of blood eosinophil concentration and in a sharp fall of sputum eosinophil number OPV1 changes correlation with changes in ECP in the course of treatment. A close correlation between changes in eosinophil count, FVD indices, IgE and ECP levels during the treatment indicate relief of inflammation in BA patients.

Adult↗

PubMed2006

[Correlative analysis between serum dihydropyrimidine dehydrogenase, activity, concentration of 5-fluorouracil and adverse events in the treatment of advanced gastric cancer patients].

BACKGROUND & OBJECTIVE: Toxicities and their severities vary among advanced gastric cancer patients when they receive the same regimen containing continuous infusion of 5-fluorouracil (5-FU). Dihydropyrimidine dehydrogenase (DPD) is the key rate-limiting enzymes which is closely related to toxicities of 5-FU in chemotherapy. This study was to explore the relationship between activity of DPD and concentration of 5-FU, and their correlation to adverse events among advanced gastric cancer patients treated with the same regimen containing 5-FU continuous infusion. METHODS: Patients received the same regimen (intravenous injection of paclitaxel 75 mg/m(2), leucovorin 200 mg/m(2) and 5-FU 375 mg/m(2), continuous infusion of 5-FU 2.5 g/m2 for 46 hours every two weeks). The peripheral blood was collected from 36 patients with advanced gastric cancer before and after chemotherapy to detect the activity of DPD and concentration of 5-FU by high-performance liquid chromatography (HPLC). Adverse events were assessed every cycle. RESULTS: Serum activity of DPD revealed a unimodel distribution, which globally fits to a guassian distribution (range 1.56-6.01). Mean and median DPD activity values were 2.38 and 2.13, respectively. No total DPD deficiency was found in the patients. The concentration of 5-FU varied from 179.2 microg/L to 1 589.2 microg/L, which demonstrated normality distribution after a logarithmic transformation was applied. The DPD activity was inversely correlated with 5-FU concentration (r=-0.376, P=0.024). The patients with low activity of DPD were more frequently suffering from severe diarrhea, mucositis, and myelosuppression. And high level of 5-FU concentration led to the increase of adverse events. CONCLUSION: Pre-chemotherapy DPD activity and 5-FU concentration during chemotherapy vary among gastric cancer patients, which may help to prevent severe toxicities during the treatment.

Adult↗

PubMed1993

Reverse correlation analysis of the stretch response of primary muscle spindle afferent fibers.

The nonlinear responses of deefferented primary muscle spindle afferent fibers to muscle stretching consisted of a train of action potentials which was analyzed when random changes in muscle length (band-limited gaussian white noise) were applied in cats. The upper cutoff frequency of the applied noise (the source stimulus) was varied between 1.6 and 570 Hz; the amplitude of the random input was varied between 0.002 and 1.2 mm. In a previous report the reverse correlation of 1st and 2nd order was studied for its ability to analyze data of a continuous input signal and pulsatile events in the output. Computations of the Wiener kernels h1 and h2 or their equivalents, the perispike averages of the 1st and 2nd order, were computed from the random stretch responses of muscle-spindle afferents. Then the 1st- and the 2nd-order predictions and the summation of both to random muscle stretch was estimated. A general finding was that the 1st-order component was approximately 10 times that of the 2nd-order component, when both were combined in approximation procedures to give the closest prediction of observed responses to random test stimuli. The approximation was poor when the source stimulus was less than 0.03 mm and improved when it was greater. With the increase in the upper cutoff frequency of the random source input, the approximation worsened continuously. Predictions to ramp-and-hold stimuli were computed, as well as responses to random stimulation. Limiting the upper cutoff frequency did not diminish the value of the techniques applied.

Action Potentials↗

PubMed1975

Correlation analysis of electrical noise in lipid bilayer membranes: kinetics of gramicidin A channels.

If a membrane contains ion-conducting channels which form and disappear in a random fashion, an electric current which is passed through the membrane under constant voltage shows statistical fluctuations. Information on the kinetics of channel formation and on the conductance of the single channel may be obtained by analyzing the electrical noise generated in a membrane containing a great number of channels. For this purpose the autocorrelation function of the current noise is measured at different concentrations of the channel-forming substance. As a test system for the application of this technique we have used lipid bilayer membranes doped with gramicidin A. From the correlation time of the current noise generated by the membrane, the rate constants of formation (k-R) and dissociation (k-D) of the channels could be determined. In addition, the mean square of the current fluctuations yielded the single-channel conductance lambda. The values of k-R, k-D, and lambda obtained from the noise analysis agreed closely with the values determined by relaxation measurments and single-channel experiments.

Binding Sites↗

PubMed2004

Reconstructing biological networks using conditional correlation analysis.

MOTIVATION: One of the present challenges in biological research is the organization of the data originating from high-throughput technologies. One way in which this information can be organized is in the form of networks of influences, physical or statistical, between cellular components. We propose an experimental method for probing biological networks, analyzing the resulting data and reconstructing the network architecture. METHODS: We use networks of known topology consisting of nodes (genes), directed edges (gene-gene interactions) and a dynamics for the genes' mRNA concentrations in terms of the gene-gene interactions. We proposed a network reconstruction algorithm based on the conditional correlation of the mRNA equilibrium concentration between two genes given that one of them was knocked down. Using simulated gene expression data on networks of known connectivity, we investigated how the reconstruction error is affected by noise, network topology, size, sparseness and dynamic parameters. RESULTS: Errors arise from correlation between nodes connected through intermediate nodes (false positives) and when the correlation between two directly connected nodes is obscured by noise, non-linearity or multiple inputs to the target node (false negatives). Two critical components of the method are as follows: (1) the choice of an optimal correlation threshold for predicting connections and (2) the reduction of errors arising from indirect connections (for which a novel algorithm is proposed). With these improvements, we can reconstruct networks with the topology of the transcriptional regulatory network in Escherichia coli with a reasonably low error rate.

Algorithms↗

PubMed1991

[A correlational analysis of the EEG rhythms and functional hemispheric asymmetry in children with the hyperdynamic syndrome].

Thirty-three mentally normal children aged 4.5 to 11 years with hyperdynamia were examined for their EEG. In the profile of functional asymmetry (PFA) detected by the leading hand and eye, a considerable portion, as compared to normals, was made up of ambidextrous children with no left-handers. Depending on the pattern of biopotentials, two types were distinguished in the EEG. Each of the type covered children with different PFA. The cross-correlations inside and interhemispheric relations were different in children with different PFA and depended on the EEG type. The children with hyperdynamia were shown to have the weakening of the intrahemispheric correlations by the alpha rhythm together with their potentiation according to the beta rhythms, a decrease of positive interhemispheric asymmetries, and a great number of negative asymmetries.

Attention Deficit Disorder with Hyperactivity↗

PubMed1999

DNA-ploidy analysis correlates with the histogenetic classification of thymic epithelial tumours.

The ploidy values of the epithelial component were determined in a series of thymomas and organotypic thymic carcinomas using image cytometry and the results were compared with the histological tumour subtypes according to the histogenetic classification introduced by Marino, Müller Hermelink, and Kirchner (MMHK). Forty-six cases of thymic epithelial tumours were included in the study. After reclassification according to the MMHK classification, the distribution among the subtypes was as follows: three medullary, nine mixed type, five predominantly cortical (organoid), 16 cortical thymomas, and 13 well-differentiated thymic carcinomas. Single cell preparations were made from paraffin-embedded tumour tissue and stained according to Feulgen. Ploidy analysis was performed using an automated image analysis system. In five cases, DNA cytometry could not be performed, for technical reasons. The remaining 41 cases consisted of 11 diploid and 30 non-diploid tumours. The percentage of aneuploid tumours in the different subtypes increased from medullary (0 per cent) through mixed type (44.4 per cent), predominantly cortical (75 per cent), cortical (83.3 per cent) to well-differentiated thymic carcinomas (100 per cent). DNA-ploidy determination using image cytometry correlates with the concept of the MMHK classification of thymomas.

Humans↗

PubMed2006

Correlation analysis between different parameters of conduit artery and microvascular vasodilation.

Impaired endothelial responsiveness to specific vasodilator stimuli has been used as a surrogate marker of cardiovascular risk. Multiple methods allow testing endothelial responses in both microvessels and conduit arteries, but it is still unclear whether there is a relationship in endothelial function between these two different vascular beds. Twenty-five healthy young non smoking male volunteers (age range 24-45) were enrolled. Radial (conduit) artery (endothelium-dependent) flow-mediated dilation (FMD), microvascular cutaneous reactive hyperemia (using laser Doppler) and acetylcholine-induced microvascular vasodilation (laser Doppler iontophoresis) were measured. Data were analyzed in a randomized fashion in order to test the existence of a correlation among these measures of endothelium (in)dependent vasodilation. Conduit artery FMD showed a negative correlation with resting radial artery diameter (R=0.44, P<0.05). There was a correlation between peak responsiveness to acetylcholine and peak reactive hyperemia (R=0.41, P<0.05). Conversely, absolutely no correlation was shown between FMD and measures of microvascular vasomotion, including reactive hyperemia (P=ns) and acetylcholine-induced vasodilation (P=ns). Using three different human in vivo models, we test conduit artery and microvascular endothelial vasodilation. While microvascular flow reserve measurements induced by endothelium-dependent and independent stimuli appear to be linearly correlated, we show no correlation in endothelium-dependent vasomotion between the micro- and macrocirculation.

Adult↗