Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Correlation Of Data”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 415 records · Page 23Linked to original sources

Clustering and switching as two components of verbal fluency: evidence from younger and older healthy adults.

Although verbal fluency is a frequently used neuropsychological test, little is known about the underlying cognitive processes. The authors proposed that 2 important components of fluency performance are clustering (i.e., the production of words within semantic or phonemic subcategories) and switching (i.e., the ability to shift between clusters). In Experiment 1, correlational data from 54 older and 41 younger adults indicated that both components were highly correlated with the number of words generated on semantic fluency, whereas switching was more highly correlated than clustering with the number of words generated on phonemic fluency. On semantic fluency, younger participants generated more words and switched more frequently than older participants; on phonemic fluency, older participants produced larger clusters than younger participants. In Experiment 2, among 22 young adults, divided attention decreased the number of words generated and decreased switching on phonemic fluency only. Overall, findings suggest that clustering and switching are dissociable fluency components and that switching is related to frontal-lobe functioning.

Adolescent↗

What makes a tutor effective? A structural-equations modeling approach to learning in problem-based curricula.

PURPOSE: To test and further develop a causal model of the influence of tutor behaviors on student achievement and interest in the context of problem-based learning. METHOD: Data from 524 tutorial groups involving students participating in the four-year undergraduate health sciences curriculum at the University of Limburg in 1992-93 were analyzed. The tutorial groups were guided by 261 tutors. Overall, 3,792 data records were studied, with each student participating in an average of 2.3 groups. Correlations among tutors' social-congruence, expertise-use, and cognitive-congruence behaviors, small-group functioning, and student' self-study time, intrinsic interest in subject matter, and level of achievement were analyzed using structural-equations modeling. This statistical technique allows the investigator to test causal hypotheses on correlational data by comparing the structure of data with a theoretical model. RESULTS: After minor adaptations, the hypothesized causal model of the effective tutor fitted the data extremely will. Each tutor's level of expertise use and social congruence not only directly affected his or her level of cognitive congruence but also affected other elements of the model. Level of social congruence influenced group functioning in a direct fashion, while expertise use had a slightly negative effect on the students' level of self-study time and a slightly positive effect on level of achievement. As hypothesized, the level of cognitive congruence influenced tutorial-group functioning. Level of group functioning affected self-study time and intrinsic interest. Finally, time spent on self-study influenced level of achievement. CONCLUSION: The results suggest that subject-matter expertise; a commitment to students' learning and their lives in a personal, authentic way; and the ability to express oneself in the language used by the student are all determinants of learning in problem-based curricula. The theory of the effective tutor, presented in this article, merges two different perspectives prevalent in the literature. One perspective emphasizes the personal qualities of the tutor: his or her ability to communicate with students in an informal way, coupled with an empathic attitude that enables the tutor to encourage student learning by creating an atmosphere in which open exchange of ideas is facilitated. The other stresses the tutor's subject-matter knowledge as a determinant of learning. The data presented in this article suggest that what is needed, really, is much of both.

Achievement↗

Biologic activity of polyethylene glycol12000-interferon-alpha2b compared with interferon-alpha2b: gene modulatory and antigrowth effects in tumor cells.

The relative activities of interferon-alpha2b (IFN-alpha2b) and polyethylene glycol(12000)-IFN-alpha2b (PEG-IFN-alpha2b) were assessed in cell culture studies using WM9 melanoma or ACHN renal cell carcinoma cell lines. Interferon-alpha2b and PEG-IFN-alpha2b had identical antiproliferative activities when tested in cell proliferation studies conducted with equivalent antiviral units of each IFN preparation. Neither IFN formulation was effective in inducing apoptosis in WM9 melanoma cells, but both increased slightly the percentage of ACHN cells undergoing apoptosis as assessed by Annexin V staining. Interferon-alpha2b and PEG-IFN-alpha2b both activated signal transducer and activator of transcription complexes, and the duration of complex activation was similar for both IFN formulations. Induction of different IFN-stimulated genes was assessed by Northern blotting and the quantitative real-time reverse transcription-coupled polymerase chain reaction (RT-PCR) in WM9 melanoma, ACHN renal cell carcinoma, U937 lymphoma, and MOLT-4 and Mono Mac 6 leukemia cell lines. Interferon-alpha2b and PEG-IFN-alpha2b had equivalent gene-modulatory activities within each of these tumor cell lines, although cell line-specific induction patterns were observed. When compared with the antiviral 50% inhibitory concentration (IC(50)) values, the dose-dependent gene expression data correlated with cell sensitivity to IFN treatment. Together, the drug comparability and cell sensitivity data suggest a predictive relation between dose, time, antiviral activity, and gene transcription effects. Therefore, although the specific activity of IFN-alpha2b is approximately three times greater than PEG-IFN-alpha2b, the two preparations have identical in vitro biologic activities when applied to cells at equivalent antiviral units.

Animals↗

Spectral properties of empirical covariance matrices for data with power-law tails.

We present an analytic method for calculating spectral densities of empirical covariance matrices for correlated data. In this approach the data is represented as a rectangular random matrix whose columns correspond to sampled states of the system. The method is applicable to a class of random matrices with radial measures including those with heavy (power-law) tails in the probability distribution. As an example we apply it to a multivariate Student distribution.

Journal Article↗

Lunar Fe and Ti abundances: comparison of lunar prospector and clementine data

The Lunar Prospector neutron spectrometer data correlate well with iron and titanium abundances obtained through analysis of Clementine spectral reflectance data. With the iron and titanium dependence removed, the neutron spectrometer data also reveal regions with enhanced amounts of gadolinium and samarium, incompatible rare earth elements that are enriched in the final phases of magma crystallization. These regions are found mainly around the ramparts of the Imbrium impact basin but not around the other basins, including the much larger and deeper South Pole-Aitken basin. This result confirms the compositional uniqueness of the surface and interior of the Imbrium region.

Journal Article↗

Cognitive, emotional, and quality of life outcomes in patients with pulmonary arterial hypertension.

BACKGROUND: The effects of pulmonary arterial hypertension on cardiovascular and physical function are well documented. Limited information exists regarding the effects of pulmonary arterial hypertension on cognitive function despite patient reports of problems with memory and attention. Our primary purpose was to determine if a prospectively identified cohort of pulmonary arterial hypertension patients had cognitive sequelae. Our secondary purpose was to determine the relationships between cognitive sequelae and neuropsychological test scores with depression, anxiety, and quality of life. METHODS: Forty-six adults with pulmonary arterial hypertension underwent assessment of cognitive function, depression, anxiety, and quality of life using standardized neuropsychological tests and questionnaires. The patients' scores were compared to normal population data. Medical, affective, neuropsychological, and quality of life data for patients with and without cognitive sequelae were compared using analysis of variance, Chi-square, or Fisher exact tests for categorical data. Correlations assessed relationships between neuropsychological test scores, depression, anxiety, quality of life, and medical data. RESULTS: Cognitive sequelae occurred in 58% (27/46) of the pulmonary arterial hypertension patients. Patients with cognitive sequelae had worse verbal learning, delayed verbal memory, executive function, and fine motor scores compared to patients without cognitive sequelae. Twenty-six percent of patients had moderate to severe depression and 19% had moderate to severe anxiety. Depression, anxiety and quality of life were not different for patients with or without cognitive sequelae. Our patients had decreased quality of life, which was associated with worse working memory. CONCLUSION: Patients with pulmonary arterial hypertension have cognitive impairments, depression, anxiety, and decreased quality of life. Depression, anxiety, and quality of life were similar for patients with cognitive sequelae compared to those without cognitive sequelae. Decreased quality of life was associated with worse verbal and working memory. Clinicians should be aware of adverse brain related outcomes in PAH patients. Attention to proximal determinants and possible interventions to prevent or reduce cognitive and emotional morbidity and decreased quality of life are warranted and should be an emphasis in outcomes research.

Adult↗

Experimental models for spinal cord injury research: physical and physiological considerations.

This paper describes historical and current experimental models used to develop our current understanding of the biomechanics and pathophysiology of traumatic spinal cord injury; the advantages and limitations of current experimental models; considerations for selecting an appropriate injury model based on experimental objectives; and key physiological factors in the spinal cord injury response that may interact with the injury response and alter the outcome. All of the above must be considered in the development and selection of an appropriate experimental injury model that meets specific needs. Various experimental models have been developed to study spinal cord injury and the pathophysiological and physical mechanisms responsible for tissue damage and loss of function. Such modeling may involve inherently different biomechanical variables with alternative outcomes and purposes. There is not, therefore, a single "ideal" experimental injury model just as there is no "stereotypical" clinical spinal cord injury. Instead, the goals and objectives of the research dictate specific requirements on the model. In all cases, however, both physical and physiological aspects of the model should be considered, and measured if possible, to ensure interlaboratory comparability and possible clinical relevance. Also, experimental techniques, especially anesthesia, and surgical procedures, should be carefully reviewed for interactions with the injury response or potential therapeutic interventions to ensure validity of interpretation. It is hoped that data correlating physical spinal cord injury parameters with functional outcome will ultimately be combined with data on vertebral injury and spinal failure mechanics to further our understanding of clinical injury. Such approaches should lead to interventions that reduce the incidence and severity of traumatic human spinal cord injury.

Animals↗

Clinical parameters of the normal baboons (Papio species) and chimpanzees (Pan troglodytes).

Improved equipment and advanced progressive techniques by scientists using baboons and chimpanzees in biomedical research have resulted in improved clinical laboratory data. The use of state-of-the-art clinical laboratory instruments, methodologies with improved accuracy, and an increased variety of individual tests routinely requested and performed has necessitated the comparison of current data with prior data produced in our laboratory and with those values reported in the literature. In addition to an expanded hematologic profile, including red blood cell distribution width and mean platelet volume, and a more comprehensive chemical profile of 28 individual tests, additional data collected included values for coagulation profiles, arterial blood gases, serum protein electrophoresis, and urine osmolalities. Samples for evaluation were obtained from clinically normal sedated adult baboons (Papio species) and chimpanzees (Pan troglodytes) and processed conventionally according to Good Laboratory Practice Act standards. Arithmetic means were calculated, values of 3 standard deviations or greater were eliminated, and means were recalculated to include 2 standard deviations. All data correlated well with prior in-house values, and no remarkable differences from established data were detected, thus indicating the reliability of past and present data. Data compared favorably with normal clinical values established for humans.

Animals↗

Digital radiography. A predictor of regenerate bone stiffness in distraction osteogenesis.

The newly formed regenerate bone during limb lengthening usually is assessed by observing standard plain radiographs. However, no objective data correlate the radiographic appearance with the quantitative strength of the newly formed bone. A noninvasive method was developed to assess the regenerate bone using digital radiography. The investigations were performed in a micropig animal model. The right tibia was distracted for 10 days at 2 mm per day. Digital radiography was performed after the distraction during a 10-day consolidation period. For quantitative analysis, an aluminum step wedge was placed on all images, and a region of interest was outlined in the regenerate bone. A calibration curve was calculated by measuring the corresponding gray values of the aluminum phantom. The calibration equation was used for determining the mean density in the region of interest. This method was sensitive in assessing day to day healing progress. The measurements taken the day before sacrifice were compared with torsional mechanical data using a material testing machine. The high correlation between the densimetric evaluations and the biomechanical data suggests this method is a useful tool for in vivo assessment of the regenerate bone during the consolidation period in distraction osteogenesis.

Absorptiometry, Photon↗

Factors associated with successful laparoscopic cholecystectomy for acute cholecystitis.

OBJECTIVE: This article determined which preoperative data correlated with successful completion of a laparoscopic cholecystectomy in patients with acute cholecystitis. SUMMARY BACKGROUND DATA: Although laparoscopic cholecystectomy is the procedure of choice in chronic cholecystitis, its use in acute cholecystitis may be associated with higher costs and complication rates. It is not known which patients with acute cholecystitis are likely to require conversion to open cholecystectomy based on preoperative data or if a cooling-off period with medical therapy can diminish inflammation and increase the chance of successful laparoscopic cholecystectomy. METHODS: All laparoscopic cholecystectomies done by the authors between 10/90 and 2/92 were reviewed. Data on cases of acute cholecystitis were prospectively collected on standardized data forms. RESULTS: Twenty of 281 laparoscopic cholecystectomies were done for acute cholecystitis; 7/20 patients with acute cholecystitis required conversion to open cholecystectomy compared with 6/281 patients undergoing elective operation for chronic cholecystitis. In patients with acute cholecystitis the interval from admission to cholecystectomy in the successful cases was 0.6 days vs. 5 days in the cases requiring conversion to open cholecystectomy (p = .01). Cases requiring conversion to open cholecystectomy also had higher WBC (14.0 vs. 9.0, p < .05), alkaline phosphatase (206 vs. 81, p < .02, and APACHE II scores (10.6 vs. 5.1, p < .05). Ultrasonographic findings such as gallbladder distention, wall thickness, and pericholecystic fluid did not correlate with the success of laparoscopic cholecystectomy. Patients converted from laparoscopic to open cholecystectomy required more operating room time (120 min vs. 87 min, p < .01) and more postop hospital days (6 vs. 2, p < .001). CONCLUSIONS: Laparoscopic cholecystectomy for acute cholecystitis should be done immediately after the diagnosis is established because delaying surgery allows inflammation to become more intense, thus increasing the technical difficulty of laparoscopic cholecystectomy.

Acute Disease↗

Modelling the hierarchical structure of road crash data--application to severity analysis.

Road crashes have an unquestionably hierarchical crash-car-occupant structure. Multilevel models are used with correlated data, but their application to crash data can be difficult. The number of sub-clusters per cluster is small, with less than two cars per crash and less than two occupants per car, whereas the number of clusters can be high, with several hundred/thousand crashes. Application of the Monte-Carlo method on observed and simulated French road crash data between 1996 and 2000 allows comparing estimations produced by multilevel logistic models (MLM), Generalized Estimating Equation models (GEE) and logistic models (LM). On the strength of a bias study, MLM is the most efficient model while both GEE and LM underestimate parameters and confidence intervals. MLM is used as a marginal model and not as a random-effect model, i.e. only fixed effects are taken into account. Random effects allow adjusting risks on the hierarchical structure, conferring an interpretative advantage to MLM over GEE. Nevertheless, great care is needed for data coding and quite a high number of crashes are necessary in order to avoid problems and errors with estimates and estimate processes. On balance, MLM must be used when the number of vehicles per crash or the number of occupants per vehicle is high, when the LM results are questionable because they are not in line with the literature or finally when the p-values associated to risk measures are close to 5%. In other cases, LM remains a practical analytical tool for modelling crash data.

Accidents, Traffic↗

Simultaneous quantitative UV spectrophotometric determination of multicomponents of amino acids using linear neural network.

Simultaneous determination of multicomponents of six amino acids with a novel chemometric technique-a linear neural network (LNN) algorithm is reported in this study. Based on the data correlation coefficient and standard deviation method, 17 representative wavelength points are selected from the original UV spectral data (343 points) as the original input patterns for LNN to build a neural network model. The results obtained only by iterating 15 times is satisfying, with a correlation coefficient of 0.999 and a relative small standard deviation.

Algorithms↗

A distal, high-affinity binding site on the cyclin-CDK substrate Pho4 is important for its phosphorylation and regulation.

Cyclins and cyclin-dependent kinases (CDKs) are key components of signaling pathways essential for cell growth and survival. The cyclin-CDK Pho80-Pho85 inactivates the transcription factor Pho4 in budding yeast by phosphorylating it on five sites. We isolated seven single amino acid substitutions outside of the phosphorylation sites that cause Pho4 to be constitutively active. The substitutions decrease the amount of Pho4 phosphorylation in vivo, and they increase the apparent K(M) of the in vitro phosphorylation reaction by an order of magnitude but do not alter k(cat) substantially. These data suggest that the substituted residues are part of a cyclin-CDK-binding site that is distal to the phosphorylation sites. Further analysis revealed that all of Pho4 variants were phosphorylated by Pho80-Pho85 in a more distributive manner than the wild-type protein, further supporting the idea that binding at a distal, high-affinity binding site is important in determining the processivity of Pho4 phosphorylation. In addition, computational modeling of the Pho4 phosphorylation reactions shows that the K(D) of binding between the Pho4 mutants and Pho80-Pho85 increases, confirming that the mutations are located in a relatively high-affinity "docking site" for the kinase. Interestingly, the K(D) derived from the in vitro data correlates well with the strength of the in vivo phenotypes, demonstrating that the in vitro data are relevant to the in vivo regulation of Pho4.

Amino Acid Substitution↗

Reliability of reporting left ventricular systolic function by echocardiography: a systematic review of 3 methods.

BACKGROUND: An accurate assessment of left ventricular (LV) systolic function is of central importance to the diagnosis and management of heart failure. Echocardiography is currently the technique most widely used for this purpose. METHODS: A systematic review was performed of the evidence for the accuracy of 3 echocardiographic methods--Simpson's rule, wall motion index (WMI), and subjective visual assessment--compared with radionuclide or contrast ventriculography for the assessment of LV ejection fraction (LVEF). RESULTS: Twenty-five studies were identified in which data on agreement between echocardiography and reference methods were obtainable. A further 18 studies provided correlation data alone. For Simpson's rule, Bland-Altman limits of agreement (95% CI) ranged from LVEF +/-7% to +/-25% (median +/-18%); for WMI +/-13% to +/-20% (median +/-16%); and for subjective visual assessment +/-16% to +/-24% (median +/-19%). Subject echogenicity, the nature of underlying disease, and the use of additional imaging technology, including secondary harmonic imaging and contrast agents, is likely to influence the accuracy of different methods. No method appears to systematically under- or overestimate LVEF to any major extent. CONCLUSION: These findings have important implications for the investigation of heart failure and for the practice and reporting of echocardiography.

Data Interpretation, Statistical↗

Triplet correlation in sheared suspensions of Brownian particles.

Triplet microstructure of sheared concentrated suspensions of Brownian monodisperse spherical particles is studied by sampling realizations of a three-dimensional unit cell subject to periodic boundary conditions obtained in accelerated Stokesian dynamics simulations. Triplets are regarded as a bridge between particle pairs and many-particle clusters thought responsible for shear thickening. Triplet-correlation data for weakly sheared near-equilibrium systems display an excluded volume effect of accumulated correlation for equilateral contacting triplets. As the Peclet number increases, there is a change in the preferred contacting isosceles triplet configuration, away from the "closed" triplet where the particles lie at the vertices of an equilateral triangle and toward the fully extended rod-like linear arrangement termed the "open" triplet. This transition is most pronounced for triplets lying in the plane of shear, where the open triplets' angular orientation with respect to the flow is very similar to that of a contacting pair. The correlation of suspension rheology to observed structure signals onset of larger clusters. An investigation of the predictive ability of Kirkwood's superposition approximation (KSA) provides valuable insights into the relationship between the pair and triplet probability distributions and helps achieve a better and more detailed understanding of the interplay of the pair and triplet dynamics. The KSA is seen more successfully to predict the shape of isosceles contacting triplet nonequilibrium distributions in the plane of shear than for similar configurations in equilibrium hard-sphere systems; in the sheared case, the discrepancies in magnitudes of distribution peaks are attributable to two interaction effects when pair average trajectories and locations of particles change in response to real, or "hard," and probabilistically favored ("soft") neighboring excluded volumes and, in the case of open triplets, due to changes in the correlation of the farthest separated pair caused by the fixed presence of the particle in the middle.

Journal Article↗

Micronuclei in cytokinesis-blocked lymphocytes may predict patient response to radiotherapy.

We have applied the cytokinesis-block micronucleus assay to peripheral blood lymphocytes of patients undergoing radiotherapy in pelvic and pulmonary sites, in order to evaluate the individual cytogenetic response. Our cytogenetic data correlated with the equivalent whole-body dose are homogeneous and compare well with the data presented by other authors. We have used an exponential mathematical formula to calculate the attenuation of the cytogenetic effect with time. The k coefficient (cytogenetic recovery factor) in the formula expresses the degree of attenuation. In lymphocytes from patients after radiotherapy, the trend of the micronucleus frequency observed after 2 Gy of in vitro X-irradiation demonstrates that the cytogenetic effect obtained in vitro is added to that obtained in vivo. The k coefficient is inversely proportional to the micronucleus frequency observed after 2 Gy in vitro. The micronucleus assay and the cytogenetic recovery factor are proposed as suitable diagnostic tools for application in the field of radiotherapy.

Dose-Response Relationship, Radiation↗

Risk factors for female anal incontinence: new insight through the Evanston-Northwestern twin sisters study.

OBJECTIVE: To evaluate risk factors for anal incontinence using an identical twin sisters study design to provide control over genetic variance. METHODS: A total of 271 identical twin sister pairs (mean age 47 years) completed the validated Colorectal Anal Distress Inventory questionnaire detailing the presence and severity of anal incontinence. Data were analyzed using a stepwise logistic regression with repeated binary measures to account for correlated data within twin pairs. Three different statistical models were used to analyze nonobstetric as well as obstetric risk factors separately. RESULTS: Significant risk factors for anal incontinence and higher Colorectal Anal Distress Inventory anal incontinence subscale scores included age 40 years or older (fecal: odds ratio [OR] 2.82, 95% confidence interval [CI] 1.21-6.0; flatal: OR 1.90, 95% CI 1.11-3.24), menopause (fecal: OR 2.10, 95% CI 1.15-3.8; flatal: OR 2.11, 95% CI 1.43-3.13), increasing parity (parity > or = 2; fecal: OR 3.09, 95% CI 1.25-7.65; flatal: OR 2.72, 95% CI 1.65-4.51), and the presence of stress urinary incontinence (fecal: OR 2.11, 95% CI 1.12-3.98; flatal: OR 1.72, 95% CI 1.14-2.59). Obesity was associated with significantly higher Colorectal Anal Distress Inventory anal incontinence subscale scores (mean difference 5.18, P = .007). Cesarean delivery after initiation of labor was associated with a lower prevalence of anal incontinence than vaginal birth; however, this difference was not statistically significant (17% compared with 4%, P = .11). No anal incontinence was noted in women who had only elective cesarean deliveries. CONCLUSION: Age, menopause, obesity, parity, and stress urinary incontinence are the major risk factors for female anal incontinence.

Adult↗

Characterization of the ZI domains in the Epstein-Barr virus BZLF1 gene promoter: role in phorbol ester induction.

Induction of the Epstein-Barr virus lytic cycle is mediated through the immediate-early BZLF1 gene and the coordinately regulated BRLF1 gene. The BZLF1 gene product, Zta, transactivates its own promoter, as well as the promoters of a number of lytic genes, thereby initiating a cascade of viral gene expression. Previous work identified four related elements (ZIA, ZIB, ZIC, and ZID) and a cyclic AMP response element binding-AP-1 element (ZII) that are involved in the induction of the BZLF1 promoter (Zp) by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) (E. Flemington and S. H. Speck, J. Virol. 64:1217-1226, 1990). Here we report a detailed characterization of TPA induction mediated by the ZI domains. Mutation of individual ZI domains within the context of the intact promoter significantly diminished TPA induction. Cloning of individual ZI domains upstream of a minimal promoter demonstrated that the ZIA, ZIC, and ZID domains, but not the ZIB domain, are TPA responsive. Furthermore, cloning of the ZII domain downstream of the ZI domains significantly augmented TPA induction. The critical regions within the ZIA and ZIC elements involved in binding of cellular factors were identified by using methylation interference and electrophoretic mobility shift analyses of ZI domain mutants. Four specific complexes were observed with the ZIA and ZID domains, all of which could be specifically competed for by either the ZIA or ZID domain. Methylation interference analyses of bound complexes revealed the presence of two overlapping binding sites for cellular factors in the ZIA domain, and functional studies provided evidence that both of these sites are involved in TPA induction. Functional analyses of the ZIC domain revealed that the 5' region of this domain is largely responsible for mediating TPA induction. Binding data correlated well with functional activity and revealed that the ZIC domain binds only a subset of the cellular factors that bind to the ZIA and ZID domains. Analysis of factor binding to the ZIB domain revealed only a single shifted complex, which correlated with the most slowly migrating complex observed with the ZIA and ZID domains. These data provide a direct demonstration of TPA induction mediated by the ZIA, ZIC, and ZID domains and also provide the first evidence that the ZI domains exhibit distinct functional characteristics.

Base Sequence↗