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PubMedDate not supplied

Variability of Doppler echocardiographic indexes of left ventricular filling in transplant recipients and in normal subjects.

This study examines the reproducibility and variability of pulsed wave Doppler versus continuous wave Doppler ultrasound indexes of left ventricular filling in cardiac allograft recipients and in normal subjects. The following indexes were studied: isovolumic relaxation time, pressure half-time, peak early mitral flow velocity, and peak mitral flow velocity after atrial systole. Intraobserver and interobserver variability were assessed by regression analysis. Individual components of variance (subject, reader, beat, day, and tracing) were estimated in a subset of five patients and five normal subjects, and estimated total variance defined for each group. Temporal (day-to-day) variability for 95% confidence was estimated for these patients and for normal subjects. Temporal variability in the group from which the subsets were drawn was measured from absolute and percent change in values on two occasions. Estimated and observed 95% confidence limits were compared. Intersubject variability was the largest component of variance in both transplant recipients and in normal subjects. For all indexes in transplant recipients (in the absence of rejection) and normal subjects, observed absolute mean differences (+/- 2 standard deviations) between values from recordings taken on two different days were larger than the 95% confidence limits estimated from the components of variance analysis. The observed 95% limits for transplant recipients versus normal subjects were as follows: isovolumic relaxation time, 20 msec versus 6 msec; pressure half-time, 16 msec versus 9 msec; peak early mitral flow velocity, 32 cm per second versus 17 cm per second; and peak mitral flow velocity after atrial systole, 28 cm per second versus 10 cm per second.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1998

[An analysis of variance of the integration of the vascular and germinative testicular systems in the pathogenesis of infertility].

In 162 infertile patients and 404 rats an impact was evaluated of varicocele, cryptorchidism, epididymitis, prostatitis, obstruction of the deferent ducts and effects of the electromagnetic field on the amounts and volume of spermatogonia nuclei. Sertoli cells, Leydig's cells, the number and outer diameter of arterioles, capillaries and venules. The impact of the above illnesses is at its greatest in respect of the spermatogenic epithelium, with lesser effects being exerted on the parameters of the hemomicrocirculatory bed, the most measurable changes in which occur with microvessels of the venular link. In the pathogenesis of infertility there takes place an interaction between the germinal system and hemomicrocirculatory bed of the testicle.

Analysis of Variance↗
PubMed2003

Power and measures of effect size in analysis of variance with fixed versus random nested factors.

Ignoring a nested factor can influence the validity of statistical decisions about treatment effectiveness. Previous discussions have centered on consequences of ignoring nested factors versus treating them as random factors on Type I errors and measures of effect size (B. E. Wampold & R. C. Serlin). The authors (a) discuss circumstances under which the treatment of nested provider effects as fixed as opposed to random is appropriate; (b) present 2 formulas for the correct estimation of effect sizes when nested factors are fixed; (c) present the results of Monte Carlo simulations of the consequences of treating providers as fixed versus random on effect size estimates, Type I error rates, and power; and (d) discuss implications of mistaken considerations of provider effects for the study of differential treatment effects in psychotherapy research.

Analysis of Variance↗
PubMed2003

Phylogeny of vertebrate nuclear receptors--analysis of variance components in protein sequences.

Nuclear receptors (NR) constitute a large family of proteins and play a crucial role in regulating mineral metabolism and physiological homeostasis of various organ systems. The aim of this study was to elucidate whether the variance among NRs of estrogen, androgen and vitamin-D in various vertebrate species including humans is attributed to differences between the taxonomic groups within a specific receptor (i.e. between orthologous) or between the different proteins within the taxon (i.e. between paralogous genes). Published data on 57 protein sequences of the above NRs were used for phylogenetic analysis. The results showed that in DNA- and ligand-binding regions, 94% and 70% of variance is due to differences between the three proteins. However, in non-binding regions, 47% of the variance results from differences between the three paralogous proteins. Human sequences consistently clustered with their mammal orthologous within the three groups of NR sequences, clearly indicating that evolution of human sequences is not distinct from mammal sequence evolution.

Analysis of Variance↗
PubMed2005

Variance component analysis of polymorphic metabolic systems.

The relationship between mechanistic allelic interaction in multi-gene systems and genetic contribution to population variance remains poorly understood. In order to address this problem, dynamic cellular processes must be reconciled with individual differences in a population. We suggest an approach to enable this for metabolic systems, whereby steady-state biomarker concentrations are calculated for individual systems carrying different alleles. As proof of principle, we simulated two versions of a three enzyme linear synthesis pathway, in a multi-level framework from transcription to enzyme action. The first (Standard) model incorporated conventional kinetics, whilst an analogous model included negative feedback in the form of competitive inhibition (CI). Alleles were allowed to confer different transcription rates, and genetic components of variance in biomarker concentration calculated for populations of each system type. Initial simulations of high and low expression alleles revealed substantial genetic additivity and some dominance for both system architectures. For the Standard model population, each of the three genes contributed equally, whereas CI substantially altered the relative importance of individual genes. Epistasis was limited for both model populations, never rising above 5% in extensive parameter explorations. Subsequent simulations examined a wide range of allelic transcription rates, from almost null to three orders of magnitude above baseline. Again, for both model architectures, additive and dominance effects were most prevalent, but epistasis increased substantially as allelic effects approached null. We conclude that the nature of allelic contribution to variance is dependent upon both the magnitude of conferred effect and the structure of the system in which it is embedded, and relatively little on other system parameters. We believe that implementation of this approach holds promise of a better understanding of the genotype to phenotype transition, particularly in integrating small allelic effects into larger frameworks.

Alleles↗
PubMed1989

[Quantitative computed tomographic flow measurements in aortocoronary venous bypass. I. Analysis of variance studies].

In 36 patients, 3 months after aortocoronary venous bypass (ACVB) surgery to the anterior interventricular branch of the left coronary artery, the density-time curve was assessed in the aorta and the ramus interventricularis anterior ACVB by computed tomography (CT). Mean values for area of time-density curve (1539 HU x sec.), effective width (10.9 sec.), peak CM concentration (140 HU), maximum increase of density (71 HU/sec.) and maximum decrease (53 HU/sec.) showed a significant (p greater than 0.01) difference between the results in aorta and the anterior interventricular branch ACVB for all parameters, excepting the effective width. We conclude that assessment of time density-curve parameters in the ramus interventricularis anterior ACVB is feasible; however, the results are significantly different from those obtained in the aorta. Clinical relevance of these data will be established in a second part of the study.

Adult↗
PubMed1987

Friedman and Quade tests: BASIC computer program to perform nonparametric two-way analysis of variance and multiple comparisons on ranks of several related samples.

Friedman and Quade tests are nonparametric two-way analyses of variance which may be used to compare several related samples. The Friedman test is a multisample extension of the sign test while the Quade test is an extension of the Wilcoxon signed-rank for paired samples to the case of several related samples. The Quade test may be more powerful for a small number of treatments while the Friedman test may be more powerful when the number of treatments is five or more. The present program is written in an elementary subset of BASIC and will perform the Friedman and Quade tests quickly on practically every computer programmable in BASIC. It may i.e. be used to analyze biomedical data where the response of experimental subjects to a stimulus is monitored at time intervals.

Analysis of Variance↗
PubMed2006

Estimating the power of variance component linkage analysis in large pedigrees.

Variance component linkage analysis is commonly used to map quantitative trait loci (QTLs) in general pedigrees. Large pedigrees are especially attractive for these studies because they provide greater power per genotyped individual than small pedigrees. We propose accurate and computationally efficient methods to calculate the analytical power of variance component linkage analysis that can accommodate large pedigrees. Our analytical power computation involves the approximation of the noncentrality parameter for the likelihood-ratio test by its Taylor expansions. We develop efficient algorithms to compute the second and third moments of the identical by descent (IBD) sharing distribution and enable rapid computation of the Taylor expansions. Our algorithms take advantage of natural symmetries in pedigrees and can accurately analyze many large pedigrees in a few seconds. We verify the accuracy of our power calculation via simulation in pedigrees with 2-5 generations and 2-8 siblings per sibship. We apply this proposed analytical power calculation to 98 quantitative traits in a cohort study of 6,148 Sardinians in which the largest pedigree includes 625 phenotyped individuals. Simulations based on eight representative traits show that the difference between our analytical estimation of the expected LOD score and the average of simulated LOD scores is less than 0.05 (1.5%). Although our analytical calculations are for a fully informative marker locus, in the settings we examined power was similar to what could be attained with a single nucleotide polymorphism (SNP) mapping panel (with >1 SNP/cM). Our algorithms for power analysis together with polygenic analysis are implemented in a freely available computer program, POLY.

Chromosome Mapping↗
PubMed2006

Developmental genetic analysis of seed size in soybean (Glycine max).

Seed size is one of the important factors of soybean [Glycine max (L.) Merrill] yield. There have been lots of reports about genetic effects and physiology--ecological researches on seed size, but the genetic behaviors of genes during seeds development were rarely discussed. Analysis of main genetic effects for fresh seed size (FSS) and dry seed size (DSS) of soybean was conducted with diallel cross data by using a seed genetic model. Analyses of unconditional and conditional variances and correlations were used to evaluate the developmental behavior of soybean. The phenotypic means of FSS and DSS in soybean at eight stages among three generations reached the highest value at 9/6 and 9/13, respectively. The means of FSS decreased dramatically after 9/6, but the means of DSS maintained relatively stable tendency at corresponding periods. The unconditional variance analysis showed that FSS and DSS were controlled by embryo, cytoplasmic and maternal effects in the whole growth period. Genetic effects due to cytoplasmic and maternal effects were relatively important for FSS and DSS at most of the growth periods. Conditional variance analysis showed that genes from different genetic system expressed discontinuously in the whole growth period. The net genetic effects due to cytoplasmic and maternal plant on FSS and DSS were larger than those of embryo effects at most of the growth periods. Different genetic system can affect the relationship of various stages to mature solely or simultaneously. Embryo additive effects at 8/16, embryo dominance effects at 8/9 and 8/16, maternal plant dominance effects at 8/2 and 8/16 could ultimately affect the performance of FSS at maturing stage. Embryo additive effects at 8/2 and 9/13, cytoplasm effects at 8/9, maternal plant dominance effects at 8/2 could ultimately affect the performance of DSS.

Analysis of Variance↗
PubMed2006

[Ultrasonographic assessment of infantile hip by the Graf method].

BACKGROUND: Ultrasonography of the hip performed by the Graf method is widely accepted as an important diagnostic and treatment tool for hip dysplasia. This study aims to examine the reliability and reproducibility of the interpretations of ultrasound scans by general orthopedists. METHODS: Thirteen examiners evaluated five hip ultrasounds of the same normal child. The examiners measured alpha and beta angles according to Graf. Statistical analysis was performed by variance analysis (ANOVA) and agreement was calculated and expressed as the intraclass correlation coefficient (ICC). RESULTS: The alpha angle mean was 37.32 degrees (11.12) and the beta angle mean was 45.05 degrees (10.49). Error of the intra-observer was 17.65 for the alpha angle and 17.63 for the beta. Error of the inter-observer was 7.68 for the alpha angle and 17.21 for the beta. ICC intra-observer was 0.18 for the alpha angle and 0.29 for the beta. ICC inter-observer was -0.02 for the alpha angle and 0.3 for the beta. CONCLUSIONS: Ultrasound of the infantile hip using the Graf method is an important tool for the assessment of developmental dysplasia of the hip, however, it must be emphasized that preciseness of interpretation requires training and frequent use.

Analysis of Variance↗
PubMedDate not supplied

[Pediatric version of the Adequacy Evaluation Protocol: application of the four Diagnostic Related Groups most frequently used in a pediatric hospital at La Coruña].

BACKGROUND: There is wide-spread consensus that a part of the use of hospital resources is inadequate in the sense that the patients receive services that do not provide them with any significant benefits, or that could be more beneficial, or less costly, with a lower care standard. The main aim of this work is to determine the percentage of inadequate admissions and stays in hospital for the four most frequent Diagnosis-Related Groups (DRGs) in a maternity-children's hospital through the retrospective application of the paediatric version of the Adequacy Evaluation Protocol (AEP). METHOD: It was a retrospective study in which 353 out of the 361 medical records that made up the covered population were analysed. Chi-square and linear trend were the statistical analysis methods used. A variance analysis and the Scheffé multiple comparison test were applied to the average values obtained. RESULTS: The admissions were judged to be adequate in 284 (80.5%) of the cases and inadequate in 69 (19.5%). Of the stays in hospital, 76% were deemed to be appropriate and 24% inappropriate. In DRG 030 (stupor and trauma-related coma, coma < 1 hour, age 0-17), a direct relation can be found between the length of the stay in hospital and the inappropriate use of hospitalisation. CONCLUSIONS: The results of this study show that a substantial proportion of the use of the hospital is inappropriate and that, particularly in DRG 030, this use is probably handled in an overly conservative way.

Analysis of Variance↗
PubMed1998

Fluoride release from three different types of glass ionomer cements after exposure to NaF solution and APF gel.

The objective of this study was to evaluate the fluoride release from three different types of glass ionomer cements and the fluoride release after exposure to NaF solution and APF gel. After determining the fluoride release during 28 days in artificial saliva, specimens were divided into two groups and exposed to NaF solution and APF gel for 2 min during 20 days. For each material, the release was highest during the first day, but Kromoglass released statistically significantly higher amounts of fluoride than the other. Vitrabond and Dyract followed in order. The differences in all groups were not statistically significant after third day. For statistical analysis: Paired- T Test, Variance Analysis and Duncan's Multiple Range Test were used. After exposure to NaF solution and APF gel all glass ionomer cements were recharged but the specimens exposed to APF gel were statistically significantly more recharged than NaF solution. As a result we conclude that glass ionomer cements can act as a rechargeable slow fluoride release systems and especially in caries active children, topical NaF applications with glass ionomer cements could be recommended as a preventive measure. We conclude that these results should be supported with long term and in vivo studies.

Acidulated Phosphate Fluoride↗
PubMed2000

Analysis of variance for gene expression microarray data.

Spotted cDNA microarrays are emerging as a powerful and cost-effective tool for large-scale analysis of gene expression. Microarrays can be used to measure the relative quantities of specific mRNAs in two or more tissue samples for thousands of genes simultaneously. While the power of this technology has been recognized, many open questions remain about appropriate analysis of microarray data. One question is how to make valid estimates of the relative expression for genes that are not biased by ancillary sources of variation. Recognizing that there is inherent "noise" in microarray data, how does one estimate the error variation associated with an estimated change in expression, i.e., how does one construct the error bars? We demonstrate that ANOVA methods can be used to normalize microarray data and provide estimates of changes in gene expression that are corrected for potential confounding effects. This approach establishes a framework for the general analysis and interpretation of microarray data.

Female↗
PubMed2003

Longitudinal variance-components analysis of the Framingham Heart Study data.

The Framingham Heart Study offspring cohort, a complex data set with irregularly spaced longitudinal phenotype data, was made available as part of Genetic Analysis Workshop 13. To allow an analysis of all of the data simultaneously, a mixed-model- based random-regression (RR) approach was used. The RR accounted for the variation in genetic effects (including marker-specific quantitative trait locus (QTL) effects) across time by fitting polynomials of age. The use of a mixed model allowed both fixed (such as sex) and random (such as familial environment) effects to be accounted for appropriately. Using this method we performed a QTL analysis of all of the available adult phenotype data (26,106 phenotypic records). In addition to RR, conventional univariate variance component techniques were applied. The traits of interest were BMI, HDLC, total cholesterol, and height. The longitudinal method allowed the characterization of the change in QTL effects with aging. A QTL affecting BMI was shown to act mainly at early ages.

Adult↗
PubMed1996

Recombinant human erythropoietin corrects anaemia during the first weeks after renal transplantation: a randomized prospective study.

BACKGROUND: Studies on the effect of recombinant human erythropoietin (rHuEpo) on haematopoiesis in patients with kidney transplants, have been limited to progressive chronic graft failure, late after transplantation. In the present prospective randomized study, the efficacy of rHuEpo in the correction of anaemia during the first weeks after renal transplantation (RTP) was evaluated. METHODS: Patients were allocated to either an Epo- (n = 14) or a non-Epo-treated group (n = 15). Epo (150 U/kg.week s.c.) was started at a haematocrit (Hct) < 30% and was increased at weekly intervals by 30 U/kg.week, as long as Hct remained < 25%. RESULTS: In the Epo group, Hct increased from a nadir of 22 +/- 4% 2 weeks after RTP to 30 +/- 4% at week 4 and to 36 +/- 4% at week 6 (P < 0.001 and P < 0.0001 respectively vs week 2). Corresponding values in the non-Epo group were 25 +/- 6%, 28 +/- 6% (P = NS) and 32 +/- 6% (P < 0.05 vs week 2) (overall evolution Epo vs non-Epo: P = 0.038 by variance analysis). The differences in Hct between the Epo and non Epo group were even more marked in patients without major complications (variance analysis P = 0.009). The Epo-treated patients required fewer post-surgical blood transfusions (0.005 vs 0.014/days follow-up, P < 0.05), in spite of greater post-surgical blood losses, especially at day 1 (P < 0.05) and the presence of more major complications (7 vs 4) and a higher number of ganciclovir-treated patients (4 vs 0; P < 0.05). The maximum Epo dose after RTP was > 2x higher than the one required before RTP (197.1 +/- 45.1 vs 85.0 +/- 76.0 U/kg.week; P < 0.05). CONCLUSIONS: It is concluded that rHuEpo during the first weeks after RTP is of benefit in the correction of the Hct in the early post-surgical period, in spite of relative Epo resistance.

Adult↗
PubMed1983

Evaluation and propagation of confidence intervals in nonlinear, asymmetrical variance spaces. Analysis of ligand-binding data.

Two problems that are often overlooked in studies employing nonlinear least-squares techniques for parameter estimation are confidence-interval estimation and propagation. When the parameters are correlated, the variance space and consequently the confidence intervals are nonlinear and asymmetrical. The presented mathematical method for the evaluation of confidence intervals and error propagation addresses these problems. The examples employed to demonstrate these methods include linear least-squares and the nonlinear least-squares analysis of ligand-binding problems, such as hormone receptor interactions and oxygen binding to human hemoglobin. The mathematical procedures have proven very useful for analyzing the molecular mechanism of cooperativity in human hemoglobin (Johnson, M. L., and G. K. Ackers, 1982. Biochemistry 21:201-211).

Computers↗