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PubMed1976

[Correlation analysis in studying the mechanism of action of smooth muscle stimulants].

The presence of correlation between the value of the maximal effects of acetylcholine and other cholinomimetics, as well as serotonin, barium chloride and depolarizing solution was studied on an isolated strip of rat stomach. It was shown that the effect of acetylcholine closely correlated with the effects of other cholinomimetics, to a lesser degree with the effects of barium chloride and depolarizing solution, and least of all with the effect of serotonin. It is proposed to use the degree of this correlation to analyze the point of action of different drugs and processes of coupling the receptor stimulation with the observed effect. It was shown that the point of convergence of the ways of coupling of the three latter influences preceded the convergence of their common way with the way of coupling of the cholinomimetic effects.

Acetylcholine↗
PubMed1981

[Correlation analysis of coagulogram indices in stroke].

With the use of a "Minsk-32" computer correlations between expanded coagulograms taken from 850 patients with ischemic cerebral stroke and 146 patients with cerebral hemorrhage were analyzed. The statistical parameters of the coagulograms and the matrices of their pair correlation quotients were calculated separately in three groups of patients, i. e. under 45, 45 to 59 and 60 years of the age and older. It was found that it was the plasma tolerance of heparin, in combination with the plasma recalcification time, the fibrinogen content, the fibrinolytic activity and the thrombotest that were the most reliable tests for evaluating the hemocoagulation status and its changes in the process of anticoagulant and hemostatic therapy of the stroke. The correlations between the coagulogram parameters varied depending on the stroke type and the patients' age. This should be taken into consideration while instituting individualized therapy.

Age Factors↗
PubMed1998

Correlation analysis of somatosensory evoked potential waveforms: clinical applications.

OBJECTIVE: To assess the validity of the correlation coefficient (CC) as a diagnostic tool in evaluating somatosensory evoked potential (SEP) waveforms. DESIGN: SEP waveforms were recorded over the spine and scalp in response to tibial nerve stimulation at the ankle for 30 patients. SETTING: A general community, ambulatory, private referral center. PATIENTS: Patients were all ambulatory and were selected randomly from among existing patient records at the medical center. MAIN OUTCOME MEASURE: The test for validity uses the CC to verify reproducibility. The test for side-to-side symmetry uses the CC to obtain a measure of similarity between left and right tibial scalp responses. For both tests, a table is presented with CCs for normal subjects. If the CC for each patient falls below the appropriate critical value from the table, then the CC is taken to be abnormal; p values are provided at specific levels in this table. RESULTS: A new data base for the means and critical values of CCs with corresponding p values is established for normal subjects. Most of the patient data reveal significant CC nonreproducibility and lack of symmetry in tibial scalp SEP waveforms. CONCLUSION: The CC provides objective and quantitative waveform information that complements latency and amplitude measurements in the clinical interpretation of tibial scalp SEP waveforms.

Algorithms↗
PubMed2004

Whole-brain voxel-based correlation analysis between regional cerebral blood flow and intelligence quotient score in Parkinson's disease.

The correlation between regional cerebral blood flow (rCBF) and intelligence quotient (IQ) score was investigated in patients with Parkinson's disease (PD) without severe dementia. We analyzed the (9mTc-ethyl cysteinate dimer single-photon emission computed tomography quantitative images and Revised Wechsler Adult Intelligence Scale scores of 44 PD patients using statistical parametric mapping. Verbal IQ positively correlated with rCBF in the right ventral striatum and the bilateral prefrontal cortex, performance IQ positively correlated with rCBF in the right operculum, insula and the left middle temporal gyrus, and full-scale IQ positively correlated with rCBF in the right operculum, insula and the ventral striatum. The identified areas may be functionally related to mild to moderate cognitive impairment in patients with PD.

Aged↗
PubMed1986

Cross-correlation analysis of intracellularly recorded synaptic activities: an evaluation of the method through computer simulation.

Cross-correlation of 'spontaneous' synaptic activities intracellularly recorded from pairs of neurons may be used to detect shared synaptic input, which could remain hidden in the raw data by the non-synchronized postsynaptic potentials (PSPs); besides, if a normalized cross-correlation function is adopted, the fraction of synchronized activity may be quantitatively estimated. To evaluate power and limits of this method, computer-simulated synaptic activities of pairs of neurons, in which a given percentage of PSPs were simultaneous, were subjected to this type of analysis. It was shown that percentages of shared activities as low as 4% and in some cases 2% could be revealed, with a conspicuity which was influenced by the types of associated PSPs.

Action Potentials↗
PubMed1985

Cross-correlation analysis of thalamic neurons and EMG activity in parkinsonian tremor.

Bursting activity in cells cross-correlated with electromyographic (EMG) activity during parkinsonian tremor. Statistically significant evidence of cross-correlation was found for 49% of cells located at the lesion target for relief of tremor. Statistically significant correlation was found for 90% of cells having tremor frequency power greater than twice 'average power' at nontremor frequencies. This population of cells may be involved in the generation of parkinsonian tremor.

Electromyography↗
PubMed1975

Formulation of de novo substituent constants in correlation analysis: inhibition of dihydrofolate reductase by 2,4-diamino-5-(3,4-dichlorophenyl)-6-substituted pyrimidines.

A correlation equation based solely on de novo constants was formulated for 105 2,4-diamino-5-(3,4-dichlorophenyl)-6-substituted pyrimidines acting as inhibitors of dihydrofolate reductase. An equation with seven indicator variables gives a correlation with a correlation coefficient of 0.903 and a standard deviation of 0.229. The technique used is a modification of the Free-Wilson approach. The results indicate that correlation equations with fewer parameters than the theoretical required to account for all molecular changes may often be encountered. It is also shown that cross-product terms can be used to establish the significance of cooperative substituent effects.

Chlorobenzenes↗
PubMed1985

A correlation analysis between pulse transit time and instantaneous blood pressure measured indirectly by the vascular unloading method.

Linear correlation coefficients (r) between pulse transit time (PTT) and blood pressure (BP) were evaluated on within-subject by within-condition level. Beat-to-beat systolic and diastolic BP was measured noninvasively using the vascular unloading technique (Yamakoshi, Shimazu and Togawa, 1980). PTT was determined from the time interval between the R-wave of ECG and the peak of the finger pulse wave. Five male subjects underwent a 2 min resting (RE), a 1 min cold pressor test (CP), eight 15 sec anagram tests (AN), and another 1 min CP. Significant r values were most frequently obtained for systolic BP and PTT in the RE condition. Under the CP or AN conditions, no consistent tendencies were observed. It was suggested that none of the r values are sufficiently high to warrant the use of PTT as an alternative index of BP. Some factors lowering the r values were discussed.

Adult↗
PubMed2006

Generalized two-dimensional correlation analysis of NMR and Raman spectra for structural evolution characterizations of silk fibroin.

Generalized two-dimensional (2D) correlation spectroscopy was used to characterize the structural evolution of silk fibroin as the pH changed from 6.8 to 4.8, demonstrating that the conformational transitions of silk fibroin are induced step by step as the pH decreases. 2D homo- and hetero-spectral correlation spectroscopy was used to establish the relationship between information extracted from NMR and Raman spectroscopy. This novel method reveals the structural evolution using two probes with different frequency scales (10(5-9) Hz for nuclear spin motion and 10(12-14) Hz for molecular vibration motion), reflecting the different spatial scale sensitivity to the molecular conformational change. The transition order is identified as silk I state (helix dominant) --> silk I intermediate state --> silk II intermediate state --> silk II state (beta-sheet dominant), as the pH decreases. The results may rationalize the silkworm spinning process, which undergoes the conformational transition steadily from the soluble helix state to the insoluble beta-sheet state as the pH decreases from the posterior to anterior glands.

Journal Article↗
PubMed2006

[Correlation analysis and identification of G421C in regulatory region of CYP4F2 gene with essential hypertension].

OBJECTIVE: To investigate the correlation between G421C polymorphism in the regulatory region of CYP4F2 gene and essential hypertension and its molecular mechanism. METHODS: Totally 196 hypertensive patients (hypertension group) and 219 normotensive subjects (control group) were genotyped by polymerase chain reaction-restriction fragment length polymorphism. The promoter activity with different alleles was evaluated by reporter assay. A Myb responsive element was identified using gel retardation assay. RESULTS: Significant differences were found in distribution of genotype and allele frequency of G421C between hypertension group and control group (P < 0.05), and homozygous GG genotype was independently associated with hypertension after adjustment for age, gender, body mass index, and other risk factors (odds ratios 1.87, 95% CI 1.11-3.13, P < 0.05). 421G reporter construct showed decreased promoter activity compared with 421C reporter construct. 421G existed in Myb responsive element, whereas 421C damaged this motif. CONCLUSION: G421C polymorphism in the regulatory region of CYP4F2 gene is correlated with essential hypertension. 421G allele inhibits transcription by binding affinity of Myb responsive element.

Adult↗
PubMed2002

Pharmacogenomic analysis: correlating molecular substructure classes with microarray gene expression data.

Genomic studies are producing large databases of molecular information on cancers and other cell and tissue types. Hence, we have the opportunity to link these accumulating data to the drug discovery processes. Our previous efforts at 'information-intensive' molecular pharmacology have focused on the relationship between patterns of gene expression and patterns of drug activity. In the present study, we take the process a step further-relating gene expression patterns, not just to the drugs as entities, but to approximately 27,000 substructures and other chemical features within the drugs. This coupling of genomic information with structure-based data mining can be used to identify classes of compounds for which detailed experimental structure-activity studies may be fruitful. Using a systematic substructure analysis coupled with statistical correlations of compound activity with differential gene expression, we have identified two subclasses of quinones whose patterns of activity in the National Cancer Institute's 60-cell line screening panel (NCI-60) correlate strongly with the expression patterns of particular genes: (i) The growth inhibitory patterns of an electron-withdrawing subclass of benzodithiophenedione-containing compounds over the NCI-60 are highly correlated with the expression patterns of Rab7 and other melanoma-specific genes; (ii) the inhibitory patterns of indolonaphthoquinone-containing compounds are highly correlated with the expression patterns of the hematopoietic lineage-specific gene HS1 and other leukemia genes. As illustrated by these proof-of-principle examples, we introduce here a set of conceptual tools and fluent computational methods for projecting directly from gene expression patterns to drug substructures and vice versa. The analysis is presented in terms of the NCI-60 cell lines and microarray-based gene expression patterns, but the concept and methods are broadly applicable to other large-scale pharmacogenomic database sets as well. The approach (SAT for Structure-Activity-Target) provides a systematic way to mine databases for the design of further structure-activity studies, particularly to aid in target and lead identification.

Algorithms↗
PubMed2004

[Correlation analysis of simulated MODIS vegetation indices and rice leaf area index and leaf chlorophyll content].

This paper studied the correlations between rice leaf area index (LAI), leaf chlorophyll content (CHL. C), hyperspectral data, normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), and red-edge position (REP). The results showed that LAI had a close correlation with visible and NIR bands, and CHL. C had the highest correlation with red band. A strong non-linear correlation was found between the LAI and REP of two rice varieties. For common rice, REP, EVI and NDVI were well related with LAI, but for hybrid rice, REP and EVI were more sensitive than NDVI to LAI. In 2003, REP, EVI and NDVI were well related with CHL. C.

Biomass↗
PubMed2001

The use of cross-correlation analysis between high-frequency ultrasound images to measure longitudinal median nerve movement.

Impaired nerve movement can lead to nerve injury (e.g., carpal tunnel syndrome). A noninvasive method to measure nerve movement in longitudinal section would enable an extensive analysis of nerve entrapment syndromes. A method has been developed using cross-correlation between successive high-frequency ultrasound (US) images to measure longitudinal movement of nerve and muscle. Control "phantom" experiments demonstrated the accuracy and reliability of this method at velocities of 1-10 mm/s. Increasing the frame interval between the compared frames enabled the accurate calculation of slower velocities. The correlation algorithm successfully measured relative movement when the US transducer was moved 1-3 mm over the surface of the forearm. Median nerve movement was repeatedly measured in the forearm during 30 degrees passive wrist extension in three subjects (range 2.63-4.12 mm) and index finger extension in seven subjects (range 1.59-4.48 mm). Median nerve movement values were consistent with those from cadaver studies.

Adult↗
PubMed1997

Cross-correlation analysis of motor unit activity recorded from two separate thumb muscles during development in man.

1. Multi-unit surface EMG signals were recorded from the short and long thumb abductor muscles of seventy-five children aged from 4 to 15 years and from nine adults during simultaneous abduction and extension of the left and right thumb. Ability to perform independent finger movements was investigated by timing a series of sequential finger-to-thumb oppositions. 2. Cross-correlograms were constructed from the discharges of motor units recorded from the long and short abductor muscles acting on the same thumb. In the majority of subjects, short duration central peaks were present indicating the presence of a common drive to the motoneurone pools innervating these two muscles. Except for those subjects aged 4 and 5 years, the size of these central correlogram peaks did not differ significantly between the dominant and non-dominant hands. 3. The prevalence of central cross-correlogram peaks in different subjects increased from the age of 4 years to 15 years. The size of the central cross-correlogram peak increased with age up to 10 years but did not alter significantly after this age. The duration of the central peak steadily decreased over the age range of 4 to 15 years. 4. Multilinear regression analysis of data recorded from children revealed that there was a positive, but weak, correlation between the size of the cross-correlogram peak and the rate of performance of sequential finger movements after having controlled for age.

Adult↗
PubMed1977

Correlation analysis of stimulus-evoked changes in excitability of spontaneously firing neurons.

1. Theoretical expressions for the cross-correlation function are described which relate the output spike train of a neuron to an input spike train. The cross-correlation function is related to a convolution integral of two functions: 1) a waiting-time density, which describes the probability of observing the next succeeding output spike given an arbitrary input; and 2) a conditional output autocorrelation function, which contains information related to the statistical properties of the output spike train itself, and to the carry-over of the effects of an input to subsequent intervals. 2. The primary synaptic effect appears in the cross-correlation function as a distorted version of the derivative of the PSP. Depending on the duration of the evoked excitability change, as compared to the mean output interspike interval, periodicities due to the spontaneous activity of the cell appear to a greater or lesser extent in the cross-correlation. 3. To estimate underlying excitability changes using correlation techniques, one must estimate both the cross- and the conditional output autocorrelation functions. In cases when the excitability changes are short and do not carry forward to subsequent intervals, the more readily estimated unconditional output autocorrelation can be used in place of the conditional correlation.

Animals↗
PubMed2005

Two-photon cross-correlation analysis of intracellular reactions with variable stoichiometry.

We successfully demonstrate the effectiveness of two-photon fluorescence cross-correlation spectroscopy (TPCCS) to study the complex binding stoichiometry of calmodulin (CaM) and Ca(2+)/CaM-dependent protein kinase II (CaMKII). Practical considerations are made for developing an intracellular cross-correlation assay, including characterization of the fluorescent molecules involved, calibration procedures of the setup, and optimal measurement conditions. Potential pitfalls and artifacts are discussed, and the complex stoichiometry of the molecular system is accounted for by a new experimental and theoretical framework for TPCCS. Our tailored model accommodates up to 12 red-labeled CaMs binding to a single green-labeled dodecameric CaMKII holoenzyme and accounts for the probability distributions of bound ligand as well as the respective changes in fluorescence emission upon binding. The model was experimentally demonstrated both in solution and in living cells by analyzing the binding of Alexa 633(C2)CaM to eGFP-CaMKII under different biochemical conditions known to induce the basal, activated, and autophosphorylated forms of the enzyme. Key binding parameters, such as binding degree, concentrations of reactants, and binding affinities, were determined under varying conditions with certain assumptions. TPCCS thus offers the unique ability to test our biochemical understanding of protein dynamics in the intracellular milieu.

Biophysical Phenomena↗
PubMedDate not supplied

[Cross-correlation analysis of the background activity of visual cortex cells separated by different distances in the alert rabbit].

Values of correlation coefficients (CC) and forms of cross-correlation functions of impulse activity were studied in neurones recorded with one microelectrode or simultaneously with two sticked together microelectrodes with tangential distance between tips of 70 and 140 mcm. Three main types of cross-correlation functions were singled out differing by peaks form and modes positions. The greatest variety of forms and the greatest percentage of significantly correlated discharges of cellular pairs were found among the neurones recorded with one electrode. Mean CC of cells recorded with one electrode was significantly greater than mean CC of the neurones recorded with two microelectrodes. Comparison of the character of intercellular correlation with amplitudes of recorded spikes showed that discharges of neurones with greater amplitude mainly forestalled discharges of cells with low amplitude.

Action Potentials↗