SEARCH · PubMed Health

Results for “Correlation analysis”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

PubMed1990

Detection of ventricular tachycardia using scanning correlation analysis.

Cross correlation is an accurate method for distinguishing normal sinus rhythm (NSR) from ventricular arrhythmias. The computational demands of the method, however, have prohibited development of an implantable device using correlation. In this study, temporal data compression prior to correlation analysis was used to reduce the total number of computations. Unipolar and bipolar intracardiac electrograms of NSR and 23 episodes of ventricular tachycardia (VT) from 23 patients were obtained from a right ventricular apex electrode catheter during routine electrophysiology studies. The data were filtered (1-11 Hz), digitized (250 samples/sec) and temporally compressed to 50 samples/sec. Data compression removed four out of every five samples by only saving the sample with the maximum excursion from the last saved sample. The average squared correlation coefficient (r2) was computed for the NSR and VT episodes using each patient's NSR waveform as a template. In all 23 patients, the r2 values showed large separation between NSR versus VT in both unipolar (0.93 +/- 0.05 vs 0.20 +/- 0.16, P less than 0.005) and bipolar (0.91 +/- 0.07 vs 0.17 +/- 0.11, P less than 0.005) electrode configurations using template lengths of 80% the intrinsic interval (avg +/- SD). Narrow templates (40% intrinsic interval or less) often resulted in multiple r2 peaks during each heart cycle and degraded the r2 separation (n = 10, P less than 0.005). High pass filtering at 3 Hz also degraded the r2 separation (n = 10, P less than 0.05). Standard noncompressed correlations indicated that data compression had negligible effects on the results. Thus, a computationally efficient cross correlation method was found to be a reliable detector of VT.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Naloxone affects both pharmacokinetics and pharmacodynamics of morphine. Application of direct correlation analysis.

Direct correlation analyses between the distribution of morphine (pharmacokinetics) and the biochemical effects of the drug on monoamine metabolism (pharmacodynamics) are reported for dissected regions of the brain. Determinations of morphine and monoamine-related substances were carried out in the same sample by high performance liquid chromatography with electrochemical detection. Naloxone, an antagonist of morphine, significantly shortened the biological half lives of morphine in both the blood and brain tissue. Such pharmacokinetic behavior appeared to be related to the contractive effect of morphine on the bile duct, and naloxone facilitated the excretion of morphine via this route. In the striatum, significant correlations were observed between the concentrations of the metabolites of dopamine, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), and morphine with a shift to the right in the concentration-response curve on naloxone treatment indicating competitive antagonism. While significant correlations were also observed in this brain region for the metabolites of noradrenaline, 3-methoxy-4-hydroxyphenylethylene glycol (MOPEG), and 5-hydroxytryptamine, 5-hydroxyindoleacetic acid (5-HIAA), a shift to the right did not occur. Significant correlations and shifts were noted for DOPAC, HVA and MOPEG in the hypothalamus. However, no correlation was found between the concentrations of 5-HIAA and morphine in this region. In other regions such as the hippocampus and medulla oblongata, similar correlations and shifts were not observed for MOPEG and 5-HIAA or for DOPAC and HVA.(ABSTRACT TRUNCATED AT 250 WORDS)

3,4-Dihydroxyphenylacetic Acid↗

PubMed1979

Physicochemical parameters in biological correlation analysis: meaning and limits.

Correlation analysis assumes that the physicochemical factors governing the transport, metabolism and drug-receptor interaction can be factored into hydrophobic-lipophilic component, polarizability and dispersion forces, electronic and steric effects and into indeterminate factors. Using computerized regression analysis, a generalized equation can be formulated to correlate the biological response of a set of compounds with their chemical structures in terms of physicochemical parameters of substituents. In order to explore the scope of each defined physicochemical parameter, correlations between biological effects and some combination of substituent indices are discussed.

Chemical Phenomena↗

PubMed1979

Cross-correlation analysis of the lateral pulvinar and scalp EEG in man.

Cross-correlation analysis of the EEG between the lateral pulvinar and various cortical regions was made after EEG was recorded during stereotactic pulvinectomy. Cross-correlation analysis of the alpha-waves between the lateral pulvinar and the scalp EEG showed that the lateral pulvinar has the highest degree of functional connection with the pre-central area, diminishing in degree with the parietal and frontal areas, and has poor functional connections with the occipital area. From these results, it might be concluded that the lateral pulvinar may be related to motor function by functional connections with the pre-central area rather than the parietal area.

Alpha Rhythm↗

PubMed1992

Time series cross-correlation analysis of postparturient relationships among serum metabolites and yield variables in Holstein cows.

Time series cross-correlation analysis was used to determine relationships among serum beta-hydroxybutyrate, glucose, FFA, cholesterol, milk yield, DMI, and estimated net energy balance for 42 d postpartum for 14 multiparous cows. Milk yield was positively associated with beta-hydroxybutyrate concentrations on the same day, and milk yield was a primary determinant of metabolic change. Dry matter intake was negatively correlated with beta-hydroxybutyrate concentrations 3 d later and on the same day. The data supported in vitro studies showing that FFA are positively associated with beta-hydroxybutyrate production, showed that glucose concentrations are negatively cross-correlated with beta-hydroxybutyrate concentrations, and found that estimated net energy balance is negatively cross-correlated with beta-hydroxybutyrate. Analyses suggested that serum glucose and cholesterol concentrations significantly decreased with increased milk yield; analyses also suggested that elevated beta-hydroxybutyrate concentrations were associated with decreases in milk yield 6 d later. beta-Hydroxybutyrate and FFA concentrations 3 to 9 d before parturition were positively related to cholesterol concentrations, and relationships were positive between estimated net energy balance and cholesterol, suggesting that cholesterol concentrations increased as precursors for cholesterol synthesis were available. Time series cross-correlation analysis was a useful tool in examining relationships among variables when repeated samples were obtained from the same individuals.

3-Hydroxybutyric Acid↗

PubMedDate not supplied

[Use of correlation analysis of clinical and laboratory data in the treatment of patients with chronic suppurative maxillary sinusitis].

In order to objectivize clinical and laboratory data, we applied P. V. Terentyev's method of correlation analysis as modified by A. N. Zosimov when examining 60 adolescents with chronic purulent maxillary sinusitis. This approach was necessary to choose an adequate method for evaluating the therapeutic efficacy. Analysis of correlations between clinical parameters, blood profile and immune data demonstrated different relationships before and after therapy. The mathematical and graphical models proposed make it possible to evaluate objectively each type of treatment, the results being in agreement with clinical observations. These models can help predict the course of disease.

Adolescent↗

PubMed1990

Cross-correlation analysis of inhibitory interactions in dorsal cochlear nucleus.

1. Cross-correlation analysis was used to study the organization of inhibitory connections between type II or type III units and type IV principal cells in cat dorsal cochlear nucleus (DCN). Pairs of units were isolated using two microelectrodes so that information about the distance over which connections are made could be analyzed. Data were obtained from 51 pairs consisting of a type II and a type IV unit and from 22 pairs consisting of a type III and a type IV unit. The analyses in this paper concentrate on type II-type IV pairs. 2. Inhibitory troughs (ITs) are observed in the cross-correlograms of type II-type IV pairs (21/51 cases). An IT is a transient decrease in discharge probability in the postsynaptic (type IV) unit immediately after spikes in the presynaptic unit (type II). The average latency to the start of ITs is 0.73 ms, and the troughs are asymmetric with a faster leading phase. Small excitatory peaks accompany the ITs in type II units, but these are probably secondary effects associated with the IT. ITs are consistent with a monosynaptic, inhibitory connection between type II and type IV units. A variety of evidence suggests that type II responses are recorded from vertical cells, an interneuron in the deep layer of the DCN that may be glycinergic. 3. The cross-correlograms of type III-type IV pairs are more complex and variable than those of type II-type IV pairs--ITs are seen in 4/22 cases, and peaks of correlation that are symmetrically located around the origin (central mound or CM) are seen in 4/22 cases; two cases have both an IT and a CM. CMs result from shared sources of input. Whereas type II-type IV correlogram features change primarily in amplitude as stimulus conditions change, correlogram features in some type III-type IV pairs change qualitatively with stimulus conditions; correlograms are flat for some stimuli and show ITs or CMs or mixtures of the two for others. This variability suggests that the circuitry associated with type III-type IV pairs is more complex than a monosynaptic connection, and further analysis of type III-type IV pairs was not done. 4. The strength of inhibition for an IT is measured as the area under the IT (effectiveness) and as effectiveness divided by the postsynaptic discharge rate (association index).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1977

[Clinical and morphological correlational analysis of different forms of myocardial infarct].

On the basis of a mathematical analysis carried out by a "Minsk--220" computer, the correlation between the most essential morphological changes in the coronary arteries, the peculiarities of myocardial infarction, history and its clinical manifestations were studied in 320 myocardial infarction cases (148 males and 172 females over 50 years of age) with the distinction of 276 clinical and morphological signs. The numerical assessment of the conjugation indices of the morphological changes and the clinical-laboratory data permitted to evaluate the role of each of the examined factors in the genesis of primary and secondary myocardial infarctions, their spreading in the heart muscle, and their clinical manifestations. It has been demostrated that similar changes in the coronary arteries that create a background for a relative circulatory insufficiency are realized in different forms of myocardial infarction. Relative coronary insufficiency varies widely and becomes the leading cause of myocardial ischaemia. The effect of other factors is interpreted as modifying, and some of them--as triggering. The presented correlations analysis proves the rationale of assessing each case of myocardial infarction in terms of the probability theory of patho- and morphogenesis of ischaemic heart disease.

Aged↗

PubMed1992

Correlation analysis of amino acid usage in protein classes.

We present a comparative study of residue usage correlations of various organism protein sets of diverse phylogenetic species and of open reading frames of several large human viral genomes. Our correlation analysis reveals three major tendencies: (i) charge compensation reflected by the high correlation of basic with acidic residues; (ii) the positive correlations of functionally and structurally similar amino acids including many pairs of hydrophobic amino acids, all pairs of aromatic amino acids, the anionic pair (glutamate and aspartate), but not the cationic pair (lysine and arginine), moderately the hydroxyl pair (serine and threonine), the small amino acids (glycine and alanine), and many (but not all) of those having high values in the Dayhoff substitutability matrix (characteristics such as amino acid polarity or codon usage agreement, except for the wobble position, do not necessarily imply significant positive correlations); (iii) a widespread negative correlation of the aggregate strong codon group amino acids (Ala, Gly, Pro) versus the weak codon group amino acids (Lys, Ile, Tyr, Asn, Phe). Discussion and speculations relate amino acid usage correlations to protein function/structure, cellular localization, proximity in amino acid biosynthetic pathways, amino acid relative abundances, tRNA and aminoacyl synthetase availabilities, and evolutionary processes.

Amino Acids↗

PubMed1991

[A cross-correlational analysis of the background neuronal pulse trains in surviving slices of the guinea pig neocortex].

Cross-correlation analysis of interdependence of the background spike activity was carried out for pairs of adjacent neurons simultaneously recorded in the incubated slices of the neocortex of guinea-pig. Statistical correlation of spike discharges was detected in 16 out of 26 recorded pairs of the neurons. Significant correlation was observed mainly in the range of +/- 100 ms from the null point. Cross-correlation had symmetric or asymmetric maxima up to 150 ms long and negative shifts up to 200 ms long. More complex positive-negative types of cross-correlations were also obtained. The data were compared to those known from other authors for the intact brain. The contribution of intrinsic intracortical interactions and extrinsic afferent influences in these correlations of activity is discussed.

Animals↗

PubMed1990

[Biological characteristics and prognosis of supraglottic carcinoma--a multivariate correlation analysis of prognosis].

The biological characteristics of supraglottic carcinoma was studied with special reference to the correlations of various biological factors with the prognosis of the lesion. The study included 100 cases of supraglottic carcinoma treated by total laryngectomy in the First Hospital of China Medical University in the period from 1975 to 1978, and 7 factors including histopathological findings observed in serial sections of the whole larynx, clinical findings, clinical course, etc. These factors were statistically analyzed by multiple correlation analysis using the theory of quantification I to determine the relations of these factors to the prognosis, as well as their participations in post operative course. 1. Twenty-seven cases died within 5 years after surgery, and 4 cases could not be followed up. 3 and 5-year survival rates were 79.5% and 72.2%, respectively, as calculated in accordance with the UICC General Rule. 2. Histopathologically 5-year survival rate was 10.0% in cases with poorly differentiated carcinoma, 78.0% in cases with moderately differentiated type, and 83.5% in cases with well-differentiated type. It was remarkably lower in poorly differentiated carcinoma than that in moderately or well-differentiated carcinoma. 3. In cases having dense lymphocyte infiltration associated with lymph follicles in peripheral region of tumor, 5-year survival rate was higher (90.4%) than in the other cases. 4. It was found that, as tumor size increased, 5-year survival rate decreased and the risk of lymph node involvement increased in the neck region. 5. 5-year survival rate was lower (48.5%) in cases with lesion infiltrating the surrounding tissues than in cases with other growth patterns. 6. Multiple correlation coefficient between prognosis and the 7 factors analyzed was 0.766. The important factors were the degree of differentiation (0.735), the degree of lymphocyte infiltration (0.260), the size of primary tumor (0.215), the growth pattern of tumor (0.141) and neck metastasis (0.028).

Carcinoma, Squamous Cell↗

PubMedDate not supplied

[The correlation analysis of amino acids: an aid in the diagnosis of chronic polyarthritis?].

This report is concerned with the correlation analysis of plasma amino acids as a possible tool to differentiate between healthy people and patients with rheumatoid arthritis (RA). Out of 450 theoretically possible correlations between plasma amino acids 95 statistically significant correlations were found in normals whereas 184 correlations were observed in RA. When the method reported here was used to find out whether an unknown sample originated from RA or normal, only one out of 40 RA-samples was incorrect. In controls 3 out of 14 failed. The possibility to use this method for common diagnostic problems is indicated.

Age Factors↗

PubMed1976

Correlation analysis of Baker's studies on enzyme inhibition. 1. Guanine deaminase, xanthine oxidase, dihydrofolate reductase, and complement.

Five correlation equations are presented which relate inhibitory activity of 578 inhibitors of guanine deaminase, xanthine oxidase, dihydrofolate reductase, and complement to their chemical structures. The use of correlation analysis in enzyme studies for drug development is discussed. The importance of indicator variables in such studies is emphasized.

Aminohydrolases↗

PubMed1975

[A correlation analysis of changes in the bioelectric activity of the brain in associative speech experiments].

The paper deals with a correlational analysis of brain biopotentials in the process of speech activity in 9 normals and 10 patients with residual symptoms of brain strokes. The authors dt and erroneous fulfillment of different types of tests (free and determined associations). It was established that in a difficult fulfillment of a speech instruction there is a compensatory involvement into the activity of the right normal hemisphere.

Adolescent↗

PubMed1991

Propagation of human complex-partial seizures: a correlation analysis.

Inter- and intrahemispheric propagation of ictal discharges was analysed in 7 epileptic patients having chronic intracranial electrodes. Five had temporal foci and two had frontal mesial foci. Correlation analysis of seizure discharge was used to detect the emergence of linear relationships between different structures both intra- and interhemispherically. This analysis included mesial and lateral temporal sites, cingulate gyri, anterior ventral and dorsomedial thalamic nuclei during the discharges of 13 ictal episodes. Correlation between temporal mesial structures was found to be low throughout seizure onset. Propagation of paroxysmal activity through the anterior ventral thalamic nuclei and cingulate gyri was observed in all cases with temporal or frontal mesial focus. Propagation of the discharge from the temporal lateral cortex to the contralateral homologue area was observed with a short delay during 4 complex-partial seizures originating in the temporal lobe. These results show that, even though the commissural pathways may have a role in propagation, it is a relatively unimportant one and they suggest that ictal activity during mesial temporal seizures may spread preferentially through the thalamic nuclei and cortical structures.

Adult↗

PubMedDate not supplied

[A spectral-correlational analysis of the electrical activity of the sensorimotor cortex and the internal geniculate body during a motor-polarization dominant].

By spectral-correlative analysis the dynamics was studied of structural changes of coherent relations of the electrical activity of the sensorimotor cortex and medial geniculate body (MGB) of the rabbit under motor polarization dominant created by the action of DC anode on the sensorimotor cortex area. It was shown, that in the power spectra of the MGB, besides the increase of the delta-region components in interstimulus intervals at the dominant, during the action of the sound stimulus a distinct maximum appeared in the alpha-rhythm range of the electrical activity of MGB of the "dominant" hemisphere. The coherence increase of the delta-range of the MGB and the sensorimotor cortex electrical activity in the "dominant" part of the brain was manifested exclusively in the period of sound stimulus action.

Alpha Rhythm↗

PubMed1991

Horizontal interactions between visual cortical neurones studied by cross-correlation analysis in the cat.

1. To explore the functional significance of horizontal neural connections in the extent of a 'hypercolumn' of the cat visual cortex, we carried out cross-correlation analysis of spike trains recorded simultaneously from a pair of neurones separated horizontally by less than 1 mm. 2. Significantly correlated firings, which were found in sixty-eight pairs of cells among 327 pairs analysed, were classified into three types on the basis of their functional implications: (1) excitatory interactions, (2) inhibitory interactions and (3) common inputs to both neurones of a pair from other sources. 3. Of these three types, common inputs were encountered most frequently. Excitatory interactions were always accompanied by common inputs. Inhibitory interactions were observed least frequently. 4. The proportion of cell pairs with correlated firings was high in pairs with a horizontal separation of less than 200 microns and decreased markedly with a horizontal separation of more than 400 microns. 5. Regarding laminar locations of cells, common inputs and excitatory interactions were often observed in layers II + III and V, whereas laminar bias was not seen in inhibitory interactions. 6. With respect to difference in orientation preference between two cells, all the three types of correlations were observed, mostly in cell pairs with a difference of less than 45 deg. In particular, common inputs and excitatory interactions were often seen in cell pairs with matched orientation preferences, but inhibitory interactions were found mostly in those with slightly different orientation preferences. In addition, common inputs and excitatory interactions tended to be found between cells with the same eye preference. 7. These results suggest that horizontal functional interactions exist mainly in a range of up to 400 microns as far as the extent of a hypercolumn of the visual cortex is concerned, and these interactions operate effectively between cortical cells with similar receptive field properties except for inhibitory interactions.

Action Potentials↗

PubMedDate not supplied

[Spectral correlation analysis of the potentials of the neocortex and certain subcortical structures during low-frequency electrical stimulation of nonspecific thalamic nuclei].

The spectral-correlation analysis of biopotentials in the cortex and some other brain structures (the anteroventral thalamic nucleus, dorsal hippocampus, lateral geniculate body, mid-brain reticular formation), in chronic experiments on alert rabbits, revealed that during electrical stimulation of thalamic mid-line nuclei within the ranges of 1-3, 4-7 and 8-10 c/s, there occured a rearrangement of the EEG frequencies; a dominant, narrow-band peak at the stimulation frequency, appeared. The coherence of the biopotentials of different cortical areas, of the cortex and subcortical formations increased during the stimulation at the frequency of the stimulation, reaching maximum values between the potentials of the visual and sensorimotor cortical areas.

Animals↗