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PubMed1985

Dorsal-ventral differences in the midbrain distribution of single neurons with head movement-correlated and locomotion-correlated firing in the golden hamster.

Movement-correlated firing was studied in 111 midbrain neurons recorded in freely behaving hamsters. For 42% of these cells, most of which lay in the deeper laminae of the superior colliculus, firing occurred principally or exclusively in association with head movements. In 38% of the neurons, most of which were in subtectal regions, activity was greatest during locomotion, but also occurred in correlation with other types of movement.

Animals↗

PubMedDate not supplied

Intraclass correlation among measures related to tobacco use by adolescents: estimates, correlates, and applications in intervention studies.

Tobacco intervention studies that employ a community trial design require adjustment to the usual analytic methods to account for the allocation of intact social groups to study conditions and the positive intraclass correlation (p) that is inevitable in such a design. In the absence of valid estimates of the relevant p, investigators seeking to establish an appropriate sample size could only guess about the magnitude of the problem. We recently published estimates of p for common measures of adolescent tobacco use, but those estimates were unadjusted for potential covariates and so represented an upper limit on the magnitude of p. This report demonstrates how estimates of intraclass correlation may be substantially reduced through regression adjustment for easily measured covariates. Results show that both the p and the residual variance can be reduced, by an average of 20 and 11%, respectively, offering greater efficiency for investigators who plan future studies and who are able to measure those covariates in their studies. Future work should seek both to replicate this work and to extend it; for example, to cohort designs where the improvements might be even greater.

Adolescent↗

PubMed1994

Interleukin 6 production in fetal rat long bone cultures is correlated with PGE2 release and does not correlate with the extent of bone resorption.

Reports from several laboratories have suggested that interleukin 6 (IL-6) may play a role in the process of bone resorption. We have extended these studies by examining the role of IL-6 in fetal rat long bone (FRLB) resorption stimulated by a variety of agents, including parathyroid hormone (PTH); 1,25 dihydroxyvitamin D3 (1,25(OH)2D3); interleukin 1 (IL-1); tumour necrosis factor alpha (TNF-alpha) and lipopolysaccharide (LPS). This model of bone resorption does not require the generation of osteoclasts in order to elicit a resorptive response and allowed us to assess whether IL-6 can directly affect osteoclastic bone resorption. We confirmed previous studies which showed that exogenous recombinant murine or human IL-6 does not stimulate bone resorption and demonstrated that IL-6, when added prior to the addition of parathyroid hormone, caused a significant but somewhat variable inhibition at 120 hours. Exogenous PGE2 stimulated both IL-6 production and resorption in FRLB cultures in a concentration-dependent manner. Endogenous production of IL-6 in fetal rat long bone (FRLB) cultures was stimulus dependent and generally correlated with prostaglandin E2 (PGE2) levels in the same cultures. However, endogenous IL-6 production did not correlate with the extent of bone resorption, except when IL-1 and PGE2 were used as stimuli. Addition of indomethacin and diclofenac to IL-1 stimulated cultures demonstrated that both the IL-6 production and bone resorption were largely PGE-2 dependent. Neutralizing anti-IL-6 antibodies inhibited IL-6 activity in FRLB cultures but did not affect bone resorption, even in the IL-1 stimulated cultures.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1984

Pathoanatomic correlates of regional left ventricular wall motion assessed by equilibrium radionuclide angiocardiography: a postmortem correlation.

The pathoanatomic correlates of qualitative assessment of regional wall motion (RWM) on routine equilibrium radionuclide angiocardiography (ERNA) were evaluated in 62 patients who had ERNA within 3 months before they died. Of 51 patients with abnormal RWM, 46 (90%) had gross myocardial lesions at autopsy. Of 11 patients with normal RWM, 9 (82%) had normal myocardium. Complete agreement of RWM with postmortem findings in all left ventricular segments occurred in 32% of the patients. Compared with postmortem findings, abnormal RWM on ERNA overestimated the number of macroscopically abnormal segments in 21% of the patients and underestimated in 47%. Of 372 segments analyzed, the overall sensitivity, specificity and predictive value of abnormal RWM on ERNA for detecting gross myocardial infarction or fibrosis was 73%, 75% and 83%, respectively. There were 35 false-positive segments (9%) (15 patients). In 27 of these segments (77%), severe stenosis of the coronary artery supplying the segment or electrocardiographic left bundle branch block could explain these findings. There were 61 false-negative segments (16%) (30 patients). In 55 of these segments (90%), either nontransmural infarction or masking by severe adjacent asynergy provided a potential explanation. Thus, qualitative analysis of RWM on routine ERNA correlates well with postmortem findings.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed2002

Correlative motions and memory effects in molecular dynamics simulations of molecules: principal components and rescaled range analysis suggest that the motions of native BPTI are more correlated than those of its mutants.

In this work MD simulations of the native bovine pancreatic trypsin inhibitor (BPTI) and 16 mutants were done in vacuum in order to study memory effects in the mutants using principal component analysis (PCA) and the rescaled range analysis (Hurst exponents). Both PCA and the rescaled range analysis support our previous proposition, based on PCA of lysozyme, that the motions of a native protein are more correlated than those of mutants. The methods are compared, the nature and applications of the rule and the role of the long-range correlations in MD time series (i.e. memory) are discussed in the context of collective motions.

Algorithms↗

PubMed2005

Comparison of distribution, agreement and correlation between the original and modified Merle d'Aubigné-Postel Score and the Harris Hip Score after acetabular fracture treatment: moderate agreement, high ceiling effect and excellent correlation in 450 patients.

BACKGROUND: In acetabular fracture treatment, 3 disease-specific outcome scores are mainly used: the original and modified Merle d'Aubigné-Postel Score, and the Harris Hip Score. METHODS: The original and modified Merle d'Aubigné-Postel Score and the Harris Hip Score were recorded in 1,153 follow-ups of 450 patients. 492 follow-ups were excluded because factors other than the acetabular fracture were found to affect the outcome scores. This gave 661 patient records for the study. RESULTS: The Spearman correlations were between 0.81 and 0.89. The quartile analyses showed Kappa agreement between 0.45 and 0.55. About 40% of the observations were classified into another quartile when switching from one outcome score to another. The 25th and 50th percentiles comprised 85% and 95% of the total numeric scores, respectively, while the 75th percentiles showed ceiling value (100% of the maximum) in all 3 scores. INTERPRETATION: Despite the excellent overall correlation between the outcome scores, the Kappa agreements were only moderate. The scores were all skewed in distribution with considerable ceiling effects that could limit their clinical use. The scores did not capture any differences in 25% of the observations at the upper end of the scales.

Acetabulum↗

PubMed1998

Activation of the MAP kinase pathway by FGF-1 correlates with cell proliferation induction while activation of the Src pathway correlates with migration.

FGF regulates both cell migration and proliferation by receptor-dependent induction of immediate-early gene expression and tyrosine phosphorylation of intracellular polypeptides. Because little is known about the disparate nature of intracellular signaling pathways, which are able to discriminate between cell migration and proliferation, we used a washout strategy to examine the relationship between immediate-early gene expression and tyrosine phosphorylation with respect to the potential of cells either to migrate or to initiate DNA synthesis in response to FGF-1. We demonstrate that transient exposure to FGF-1 results in a significant decrease in Fos transcript expression and a decrease in tyrosine phosphorylation of the FGFR-1, p42(mapk), and p44(mapk). Consistent with these biochemical effects, we demonstrate that attenuation in the level of DNA synthesis such that a 1.5-h withdrawal is sufficient to return the population to a state similar to quiescence. In contrast, the level of Myc mRNA, the activity of Src, the tyrosine phosphorylation of cortactin, and the FGF-1-induced redistribution of cortactin and F-actin were unaffected by transient FGF-1 stimulation. These biochemical responses are consistent with an implied uncompromised migratory potential of the cells in response to growth factor withdrawal. These results suggest a correlation between Fos expression and the mitogen-activated protein kinase pathway with initiation of DNA synthesis and a correlation between high levels of Myc mRNA and Src kinase activity with the regulation of cell migration.

3T3 Cells↗

PubMed2005

Fusion of respiration-correlated PET and CT scans: correlated lung tumour motion in anatomical and functional scans.

Lower lobe lung tumours in particular can move up to 2 cm in the cranio-caudal direction during the respiration cycle. This breathing motion causes image artefacts in conventional free-breathing computed tomography (CT) and positron emission tomography (PET) scanning, rendering delineation of structures for radiotherapy inaccurate. The purpose of this study was to develop a method for four-dimensional (4D) respiration-correlated (RC) acquisition of both CT and PET scans and to develop a framework to fuse these modalities. The breathing signal was acquired using a thermometer in the breathing airflow of the patient. Using this breathing signal, the acquired CT and PET data were grouped to the corresponding respiratory phases, thereby obtaining 4D CT and PET scans. Tumour motion curves were assessed in both image modalities. From these tumour motion curves, the deviation with respect to the mean tumour position was calculated for each phase. The absolute position of the centre of the tumour, relative to the bony anatomy, in the RCCT and gated PET scans was determined. This 4D acquisition and 4D fusion methodology was performed for five patients with lower lobe tumours. The peak-to-peak amplitude range in this sample group was 1-2 cm. The 3D tumour motion curve differed less than 1 mm between PET and CT for all phases. The mean difference in amplitude was less than 1 mm. The position of the centre of the tumour (relative to the bony anatomy) in the RCCT and gated PET scan was similar (difference <1 mm) when no atelectasis was present. Based on these results, we conclude that the method described in this study allows for accurate quantification of tumour motion in CT and PET scans and yields accurate respiration-correlated 4D anatomical and functional information on the tumour region.

Algorithms↗

PubMed2000

Image correlation method for measuring blood flow velocity in microcirculation: correlation 'window' simulation and in vivo image analysis.

To elucidate the function of the microcirculation system, it is very important to know the blood flow velocity and its distribution in the microvessels. We have developed an automated system for measuring blood flow velocity in microcirculation by image correlation. The 'window' in the image correlation method is equivalent to the sensors in various other measurement methods. We performed simulations with virtual blood flow images consisting of random dots before measuring actual ones, and examined the optimum window shape and size. We found that by reducing the size of a circular window to the size of erythrocytes we could measure in vivo blood flow images with high accuracy. We recorded them with a high-speed video camera system at high temporal resolution, and measured the velocity in microvessels of normal Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR). SHR had higher blood velocity than WKY even though the vessel diameters were the same. Using this method to measure the blood flow velocity profile at the bent corner of SHR's arteriole at the heart systole, we found that erythrocytes flow faster at the inner side of the bend, so the vessel wall was exposed locally to higher shear stress in the hypertensive condition.

Animals↗

PubMed1994

Intraclass correlation among common measures of adolescent smoking: estimates, correlates, and applications in smoking prevention studies.

Most adolescent smoking prevention studies employ designs in which classrooms, schools, school districts, or sometimes whole communities are assigned to treatment conditions while observations are made on individual students. The critical design feature in such community trials is the nesting of intact social groups within treatment conditions. This combination requires that the treatment effect be assessed against the between-group variance; unfortunately, that variance is usually larger than for randomly constituted groups and its precision is usually less than that for the within-group variance. These factors often combine to reduce power so that it is almost impossible to detect important treatment effects in an otherwise well designed and properly executed study. To address these problems, investigators need good estimates of the intraclass correlation for the variables of interest, which together with the number of observations per unit determine the magnitude of the extra variation in the nested design. The purpose of this paper is to describe the methods and results from a study designed to generate estimates of intraclass correlation for common outcomes in adolescent smoking prevention studies and to discuss the use of these estimates in the planning of new studies.

Adolescent↗

PubMed1997

Audiological correlates of speech understanding deficits in elderly listeners with mild-to-moderate hearing loss. II. Correlation analysis.

OBJECTIVE: The study was conducted to determine the relationship between measures of auditory performance in elderly individuals. Specifically, its goal was to uncover a set of measures correlated with the set of measures of speech understanding under specific conditions of interference to gain a better understanding of decline of the "cocktail party effect" in aging. DESIGN: Audiological status and auditory performance of a group of elderly (60- to 81-yr-old) individuals were determined through a test battery. When present, the hearing loss of elderly subjects was symmetrical in the two ears and, at most, moderate. The battery included tests of speech intelligibility on the word and sentence levels, with and without the presence of interfering speech. In addition pure-tone and speech reception thresholds, perception of spectrally or temporally distorted speech and auditory resolution of frequency, time, and space were tested. Two tests received special consideration: the Speech Perception In Noise Test and the Modified Rhyme Reverberation Test. RESULTS: Results indicated that, despite the nearly normal hearing levels that characterized much of the subject group, auditory sensitivity measures showed persistent correlation to all other measures, with the exception of auditory resolution regarding frequency, time, and space. As a set, sensitivity measures accounted for more than 85% of the variance. When auditory sensitivity was controlled for, other factors underlying speech processing in the presence of interfering stimuli were uncovered, factors most likely related to the ability to perceptually segregate one speech signal from another. CONCLUSIONS: The findings suggest that, to determine the relationship between audiological/auditory test results of an elderly population, it is important to remove the effects of hearing loss through appropriate statistical methods.

Aged↗

PubMed1994

A comprehensive study of physical parameters, biomechanical properties, and statistical correlations of iliac crest bone wedges used in spinal fusion surgery. II. Mechanical properties and correlation with physical parameters.

Iliac crest wedges have been the most frequently used bone graft in spinal fusion procedures since the 1970s. Physical parameters and correlations among physical parameters of allogeneic iliac crest wedges have been described in part I of this series. This article discusses the mechanical properties, as well as their correlations with physical parameters, of iliac crest wedges. A total of 250 frozen-thawed, freeze-dried, and rehydrated iliac crest wedges were used in this study. The axial load-bearing capacities for wedges in the three subgroups showed no statistically significant differences, however, rehydrated wedges appeared to have the greatest load bearing capacity and compressive strength. In addition, rehydrated wedges were more deformable than either the frozen-thawed or freeze-dried wedges. Based on biomechanical properties, it is suggested that rehydrated (1 hour in vacuo), or frozen-thawed iliac crest wedge should be used in spinal fusion procedures, and the direct clinical application of nonrehydrated freeze-dried wedges should be avoided.

Aging↗

PubMed2000

Space intensity correlations in the near field of the scattered light: A direct measurement of the density correlation function g(r)

We show that the two point intensity correlation in the near field of the scattered light is directly related to the two point density correlation g(r). Preliminary measurements on two sets of calibrated random pinholes of 140 and 300 &mgr;m diameters, and on aqueous solutions of latex spheres of 5, 10, and 40 &mgr;m are reported. A discussion on the desirability of the technique as a simple and powerful alternative to low angle scattering will be presented.

Journal Article↗

PubMed2001

Strong correlation to weak correlation phase transition in bilayer quantum Hall systems.

At small layer separations, the ground state of a nu = 1 bilayer quantum Hall system exhibits spontaneous interlayer phase coherence. The evolution of this state with increasing layer separation d has been a matter of controversy. We report on small system exact diagonalization calculations which suggest that a single-phase transition, likely of first order, separates incompressible states with strong interlayer correlations from compressible states with weak interlayer correlations. We find a dependence of the phase boundary on d and interlayer tunneling amplitude that is in very good agreement with recent experiments.

Journal Article↗

PubMed2006

Can two-photon correlation of chaotic light be considered as correlation of intensity fluctuations?

Two-photon correlation phenomena, including the historical experiment of Hanbury Brown and Twiss, may have to be described quantum mechanically, regardless of whether the source of radiation is classical or quantum. Supporting this point, we present a ghost imaging type of second-order spatial correlation experiment of chaotic light to show that the classical understanding based on the concept of statistical intensity fluctuations does not give a correct interpretation for the observation. From a practical point of view, this experiment demonstrates the possibility of having high contrast lensless two-photon imaging with chaotic light, suggesting imaging applications for radiations for which no effective lens is available.

Journal Article↗

PubMedDate not supplied

Correlation studies of morphological and biochemical parameters in human ejaculate in various andrological diagnoses. 3rd report. Correlations between morphological and biochemical parameters.

The result of a study of correlations between morphological and biochemical parameters in human ejaculate is presented in conclusion of an extensive study of these parameters. Basing on these results, for which a statistical significance of p less than 0.05 was calculated, it can be stated that higher fructose concentrations are associated with lower sperm density; at the same time, the higher fructose concentrations correlate with a higher percentage of non-motile and of pathologically changed spermatozoa. Similar associations can be established for certain substrates which result from fructolysis. The possibility of diffusion of enzymes from the cellular components must be considered as regards the increased activities of PGK, PGI and ATPase in seminal plasma in the presence of greater sperm density. Reliable conclusions about associations between morphological characteristics and enzyme activities can be expected in the future from appropriate measurements in the cellular elements (spermatozoa, round cells) of the ejaculate. The study results provide a further insight into the biochemistry of seminal plasma and into the associations between morphological and biochemical parameters in the ejaculate.

Acid Phosphatase↗

PubMed1996

Histological grade in invasive ductal carcinoma of breast correlates with the proliferative activity evaluated by BrdU: an immunohistochemical study including correlations with p53, c-erbB-2 and estrogen receptor status.

Thirty cases of invasive ductal carcinoma of the breast were classified to histological subtype according to the General Rules for Clinical and Pathological Recording of Breast Cancer of the Japanese Breast Cancer Society and histologically graded using the Nottingham method and the correlation of histology with proliferative activity was investigated using bromodeoxyuridine (BrdU). In addition, the overexpression of p53 protein, c-erbB-2 oncoprotein and estrogen receptor (ER) were immunohistochemically examined in order to discuss the relationship with histological subtype and histological grade. Histological grade correlated positively to the BrdU labeling index (LI) and overexpression of p53. High grade carcinoma demonstrated c-erbB-2 more frequently and exhibited a low incidence of ER. However, no significant relationship was found between BrdU LI, overexpression of p53 and c-erbB-2 and histological subtype. These results suggest that the histological grade does represent the proliferative activity of tumor cells and that adding the histological grade to the pathological diagnosis in invasive ductal breast carcinoma may be useful from the clinicopathological aspect concerning tumor behavior.

Adult↗

PubMed2001

Intraclass correlation for measures from a middle school nutrition intervention study: estimates, correlates, and applications.

This article presents the first estimates of school-level intraclass correlation for dietary measures based on data from the Teens Eating for Energy and Nutrition at School study. This study involves 3,878 seventh graders from 16 middle schools from Minneapolis-St. Paul, Minnesota. The sample was 66.8% White, 11.2% Black, and 7.0% Asian; 48.8% of the sample was female. Typical fruit and vegetable intake was assessed with a modified version of the Behavior Risk Factor Surveillance System questionnaire. Twenty-four-hour dietary recalls were conducted by nutritionists using the Minnesota Nutrition Data System. Mixed-model regression methods were used to estimate variance components for school and residual error, both before and after adjustment for demographic factors. School-level intraclass correlations were large enough, if ignored, to substantially inflate the Type I error rate in an analysis of treatment effects. The authors show how to use the estimates to determine sample size requirements for future studies.

Adolescent↗