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PubMed2004

Influence of age, sex, and education on the Visual Object and Space Perception Battery (VOSP) in a healthy normal elderly population.

The assessment of visual perception and cognition forms an important part of any general cognitive evaluation. We have studied the possible influence of age, sex, and education on a normal elderly Spanish population (90 healthy subjects) in performance in visual perception tasks. To evaluate visual perception and cognition, we have used the subjects performance with The Visual Object and Space Perception Battery (VOSP). The test consists of 8 subtests: 4 measure visual object perception (Incomplete Letters, Silhouettes, Object Decision, and Progressive Silhouettes) while the other 4 measure visual space perception (Dot Counting, Position Discrimination, Number Location, and Cube Analysis). The statistical procedures employed were either simple or multiple linear regression analyses (subtests with normal distribution) and Mann-Whitney tests, followed by ANOVA with Scheffe correction (subtests without normal distribution). Age and sex were found to be significant modifying factors in the Silhouettes, Object Decision, Progressive Silhouettes, Position Discrimination, and Cube Analysis subtests. Educational level was found to be a significant predictor of function for the Silhouettes and Object Decision subtests. The results of the sample were adjusted in line with the differences observed. Our study also offers preliminary normative data for the administration of the VOSP to an elderly Spanish population. The results are discussed and compared with similar studies performed in different cultural backgrounds.

Age Factors↗
PubMed2002

Group sequential methods for an ordinal logistic random-effects model under misspecification.

Interim analyses in clinical trials are planned for ethical as well as economic reasons. General results have been published in the literature that allow the use of standard group sequential methodology if one uses an efficient test statistic, e.g., when Wald-type statistics are used in random-effects models for ordinal longitudinal data. These models often assume that the random effects are normally distributed. However, this is not always the case. We will show that, when the random-effects distribution is misspecified in ordinal regression models, the joint distribution of the test statistics over the different interim analyses is still a multivariate normal distribution, but a sandwich-type correction to the covariance matrix is needed in order to obtain the correct covariance matrix. The independent increment structure is also investigated. A bias in estimation will occur due to the misspecification. However, we will also show that the treatment effect estimate will be unbiased under the null hypothesis, thus maintaining the type I error. Extensive simulations based on a toenail dermatophyte onychomycosis trial are used to illustrate our results.

Biometry↗
PubMed1988

Time-dependent variations of transcutaneous PCO2 level in normal subjects.

Transcutaneous PCO2 (PtcCO2), which is linearly related to arterial PCO2, was continuously recorded in healthy, adult, normal volunteers for 8-h periods. Recording this variable with the apparatus employed permits measurement of changes in the level of ventilation while subjects are freely ambulant and unencumbered by invasive and flow-resistive respiratory apparatus. The time series obtained exhibited marked periodicities. The frequencies and amplitudes varied between subjects. Peak-to-peak variation was 10-20% of mean values. There was no apparent association between fluctuations in PCO2 and activity other than formal exercise. Visual inspection of the time series and preliminary statistical analysis of digitally converted data suggested that the time-dependent changes of PtcCO2 were normally distributed. However, more rigorous statistical examination revealed that in no case was PtcCO2 actually normally distributed.

Adult↗
PubMedDate not supplied

Caries preventive effect of high fluoride and xylitol containing dentifrices.

Dental examinations were conducted in 1987 on 520 of the 753 children who fully participated in a three-year field-trial, 1983-1986, of the anticaries effect of dentifrices containing fluoride and xylitol. The prevalence of decayed (D), missing (M) and filled (F) permanent teeth differed significantly among the five treatment groups. Caries prevalence was inversely related to the level of fluoride, 1250, 2500 and 5000 ppm, in the dentifrice used, but was not associated with the presence or absence of 15 mg percent xylitol. The age, number of children, and number of erupted teeth were unequally dispersed among treatment groups. The DMF teeth scores showed non-normal distributions and nonhomogeneous variances. Following an exploratory scrutiny, the DMFT data were transformed to normal distributions for intra- and inter-treatment-group evaluation. All groups showed positive, significant regressions of DMF scores with the age of the children and an inverse significant regression with DMFT scores in relation to the fluoride content of the dentifrice under test.

Adolescent↗
PubMedDate not supplied

Laminin and fibronectin distribution in normal and pathological human muscle.

The availability of antisera against collagen and non-collagen proteins of the extracellular matrix has opened new possibilities of studying fibrous infiltration in muscular diseases. We have examined muscle biopsies from 5 controls and 27 patients with various neuromuscular diseases by immunofluorescence and peroxidase-anti-peroxidase. We investigated the distribution of fibronectin and of laminin, a protein present in basement membranes. In normal muscle both were present around blood vessels, axons, muscle spindles and muscle fibres. In addition fibronectin filled the endomysial and perimysial space, the endoneurium and the space between the intrafusal fibres. In pathological muscle laminin distribution was similar to that in normal muscle, but some atrophic fibres appeared to have a thickened contour and irregular profiles were occasionally observed in the absence of histologically demonstrable muscle fibres. Fibronectin was increased in all the conditions with thickened endomysium and perimysium, without displaying any disease-specific character. Findings are compared with the few published observations on fibronectin and collagen types.

Connective Tissue↗
PubMed1993

Detection of bicarbonate administration (milkshake) in standardbred horses.

Total plasma carbon dioxide (TCO2) concentrations were measured in Standardbred horses to determine criteria to discriminate between normal horses and horses with excessive TCO2 concentrations on raceday. TCO2 concentrations from stabled horses were distributed normally with a mean of 30.2 mmol/L and a standard deviation of 1.2 (n = 192) while pre-race TCO2 concentrations were not normally distributed. The results indicate that about 50 horses per million are likely to have TCO2 concentrations greater than or equal to 35 mmol/L and that it is extremely unlikely that a normal horse would have a resting TCO2 concentration above 36 mmol/L. These values were associated with sensitivities of 67% and 59%, respectively, and with a specificity of 100%. TCO2 concentrations were relatively stable in blood samples stored at 4 degrees C for 4 days, whereas the TCO2 in specimens stored at room temperature (25 degrees C) and at ambient temperature (16-28 degrees C) declined progressively over 5 days. The accuracy and precision of the Beckman EL-ISE Auto Analyser were acceptable and within the manufacturers specified range. Paired specimens analysed using a Beckman EL-ISE Auto Analyser and a Kodak Dry Chemistry Analyser were not significantly different. However, the measurements made using the Kodak Dry Chemistry Analyser averaged 0.5 mmol/L higher than those analysed on the Beckman EL-ISE. The significance of these sources of variation in TCO2 concentration in relation to the testing of horses for 'milkshake' administration are discussed.

Administration, Oral↗
PubMed1992

Analysis of body-length distribution of Dirofilaria immitis in the cardio-pulmonary blood vessel of naturally infected dogs in Shiga Prefecture, Japan.

Body-length frequencies of Dirofilaria immitis collected from the cardio-pulmonary blood vessel of the dogs were studied in Shiga Prefecture. Japan, in October 1983 and in January and May 1984. The frequencies were not distributed normally because they included the populations of shorter-bodied worms, probably the growing younger worms, whereas the distributions of the body length of worms collected in July 1983 were proved to fit the single normal distribution. From the results of body-length distribution analysis, the worms collected in different seasons were each composed of 1 to 3 groups with different mean body-lengths, standard deviations and composition rates and successive changes were observed in the distribution patterns. According to the analysis of population structures, the infective season was estimated to range from April or May to October or November in 1983 from the respective ages of shorter-bodied worm groups. The annual rates of first infection and re-infection in 1983 determined by the population of shorter-bodied females collected in January were 48% and 93% respectively and the number of newly infecting females per dog ranged from 1 to 27 with a geometric mean of 8.5. The numbers of newly infecting female worms were distributed following the negative binomial and Poisson distributions in newly infected and already infected dogs respectively.

Animals↗
PubMed1990

Statistical properties of ABR amplitudes and latencies. Implications for computation of reference limits and relation to click phase.

A method for statistical analysis and computation of reference limits for ABR latency and amplitude variables is presented. Condensation and rarefaction ABRs from 47 healthy controls aged 4-58 years were investigated. With respect to gaussianity of distributions, the square root transformation was superior to the logarithmic transformation for amplitudes, while the logarithmic transformation performed better for amplitude ratios. Wave V latency and the I-V interpeak latency were nearly normally distributed, while other latencies and inter-peak latencies displayed varying displacement from a normal distribution. Rarefaction ABR distributions were slightly closer to normality than were condensation ABRs. Amplitude vs. following amplitude and latency vs. amplitude correlation coefficients were larger for R than for C click ABRs; thus R clicks seem to evoke a better synchronized neural volley. Most of the correlation between amplitude and latency could be explained by the influence of age and sex. Hence, age and sex matched reference limits for ABR amplitudes, without correction for latency, seem to be adequate in practical clinical work.

Acoustics↗
PubMed1991

Population distribution profiles of the activities of blood alanine and aspartate aminotransferase in the normal F344 inbred rat by age and sex.

Data on the blood enzyme activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were collected from control male and female F344 rats participating in toxicity studies at 17, 30, 56, 80 and 106 weeks of age. The data were skewed to the right with significant deviation from normality. Applying the Box-Cox transformation, it was concluded that approximately normal distributions could be obtained by using the reciprocal transformation. In general, the males showed a greater degree of heterogeneity for both enzymes. Enzyme activities at 17 weeks were lowest for both ALT and AST. There was a high correlation between the activities of blood ALT and AST, with some animals showing dramatic transient increases. Significant differences among studies with respect to the enzyme activities in rats of the same age were demonstrated.

Aging↗
PubMedDate not supplied

Nonuniform distribution of normal pericardial fluid.

It has been suggested that pericardial fluid functions as a lubricant rather than a means of transmitting pericardial pressure from one region of the heart to another. Since the functional behavior of pericardial fluid depends on fluid thickness, we measured pericardial volume and fluid distribution. In seven animals, we found that the normal canine pericardium contains 0.25 +/- 0.15 ml of pericardial fluid per kg of body weight, resulting in an average pericardial fluid thickness of only 0.34 +/- 0.27 mm. We next determined the pericardial fluid distribution in eight anesthetized mongrel dogs (17-29 kg). Color video images were recorded, while green dye (0.1 ml) was injected into the pericardial space overlying the ventricular apex to allow visualization of the pericardial fluid distribution. Within 26 +/- 17 s (range 15-53 s), dye reached the base of the heart. After 15 min of equilibration, the dye distribution appeared very nonuniform with dye accumulation over the interventricular and atrioventricular grooves. Little or no dye was present over the right and left ventricular free walls. We conclude that pericardial fluid thickness over the interventricular and atrio-ventricular grooves is sufficient to allow fluid motion in these regions. In contrast, pericardial fluid thickness overlying the ventricular free walls is very thin. Thus, in these regions the pericardial fluid functions primarily as a lubricant; and regional variations in pericardial pressure may occur.

Animals↗
PubMed2003

New monitoring technique with an ICA algorithm in the wastewater treatment process.

A new monitoring method using independent component analysis (ICA) is suggested for the wastewater treatment process (WWTP). ICA is an extension of PCA (Principal Component Analysis). While PCA can only impose independence up to the second order (mean and variance) with constraint on the direction vectors to be orthogonal, ICA imposes statistical independence up to more than second order on the individual component and has no orthogonal condition. When the variables have the Gaussian distribution, PCA itself provides a satisfactory result in monitoring performance. However, the measured variables are not often normally distributed. In this case, ICA can provide better monitoring results than PCA since ICA is based on the assumption that the latent variables are not normally distributed. In this paper, the ICA monitoring algorithm with kernel density estimation was applied to fault detection and diagnosis of the wastewater simulation benchmark. ICA with kernel density estimation gives better results than PCA in disturbance detection in spite of severe periodic features of the wastewater plant.

Algorithms↗
PubMed1976

Amobarbital--a probe of hepatic drug oxidation in man.

Some aspects of the fate of amobarbital were investigated since this drug is being used as a probe to gauge drug oxidation in man. The mean ratio of orally available over intravenously injected amobarbital was established as 0.99 +/- 0.11 (SD), by comparing integrated concentration-time curves, indicating complete absorption and absence of a first-pass effect. One subject ingested 200 mg of amobarbital sodium, and amobarbital concentrations in serum were monitored for 5 days thereafter. Elimination of amobarbital under these conditions followed first-order kinetics. One subject ingested amobarbital 7 times over a period of 3 yr; plasma clearances (32.1 +/- 1.8 [SD]ml/min) exhibited remarkable constancy, while biologic half-lives (26.5 +/- 3.1 hr) and distribution volumes (73.6 +/- 8.0 L) showed some fluctuation. The distribution of parameters of amobarbital elimination was investigated in 36 unrelated subjects. Amobarbital half-lives (23.8 +/- 6.7 hr) appeared to be normally distributed, while the clearances (36.7 +/- 10.0 ml/min) might not follow a normal distribution.

Adolescent↗
PubMed1988

Blood group antigens in the intrahepatic biliary tree. I. Distribution in the normal liver.

The distribution of six blood group-related antigens, A, B, H, Lea, Leb and sialylated Lea antigens, in the intrahepatic biliary tree was studied. These carbohydrate antigens in fixed normal liver tissues were immunostained with the use of highly specific monoclonal antibodies in an avidin-biotin-peroxidase complex method. Bile ducts expressed both ABH and Lewis blood group antigens. However, only Lewis blood group antigens could be detected in the bile ductules. Canaliculo-ductular junctions could be clearly delineated with the anti-Lewis blood group antibodies, especially with anti-Lea antibody. Small Lewis antigen-positive cells were scattered intralobularly. They were adjacent to parenchymal liver cells, mainly in Rappaport zone 1, and apparently in continuity with the portal biliary tree. Sialylated Lea antigen was found in some septal bile ducts. No blood group antigen could be detected in the bile canaliculi. These results indicate that (1) biliary tract of a given size has its own pattern of blood group antigen expression, and (2) biliary epithelial cells are not identical with regard to the phenotypic expression of their structural carbohydrates. In future, it will be possible to classify biliary epithelial cells by their blood group antigen expression.

Adult↗
PubMedDate not supplied

Hydroxymethylglutaryl-coenzyme A reductase exhibits graded distribution in normal and mevinolin-treated ileum.

Because the small bowel is a site of significant cholesterol synthesis, we determined the ileal distribution of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA reductase), the rate-limiting enzyme of the cholesterol biosynthetic pathway. Immunofluorescence microscopy on unfixed snap-frozen sections of ileum and jejunum from untreated rats or dogs showed HMG-CoA reductase in the absorptive villus epithelial cells and this appeared to be strikingly localized in their apical cytoplasm. This pattern of HMG-CoA reductase staining approximated a gradient along the villus-crypt axis with the distal villi labeling most intensely. Treatment of rats with mevinolin and/or cholestyramine for 12 days induced a 5- to 11-fold increase in ileal HMG-CoA reductase activity, and yielded a higher intensity of immunostaining without altering the pattern of enzyme distribution observed in control intestines. Also, rats with maximal induction of ileal HMG-CoA reductase exhibited a twofold increase in the number of epithelial villus cells containing prominent stacks of smooth-surfaced membranes in their apical cytoplasm as seen with electron microscopy. These observations suggest that the distal villus absorptive epithelial cells of the ileum contain high concentrations of HMG-CoA reductase, and therefore might be capable of contributing significant quantities of cholesterol to the circulation.

Animals↗
PubMed1978

Inert gas a-A differences: a direct reflection of V/Q distribution.

A computer model was developed to study the relationship between ventilation-to-perfusion (V/Q) mismatch and the development of inert gas arterial-to-alveolar partial pressure differences (a-A differences). Increasing inhomogeneity of V/Q ratio is revealed directly as an increase in the a-A difference of each gas. The quantitative relationships between the Q vs. V/Q distribution and the fractional a-A difference solubility plot (a-A difference plot) were studied and described. These studies demonstrated that for log normally distributed V/Q ratios, the area under the a-A difference plot is linearly related to the log variance of the V/Q distribution and can be estimated directly from the values obtained from six gases. The maximum a-A difference occurs for a gas whose solubility is numerically equal to the mean V/Q. The effects of departure from log normality and multimodality are discussed. We conclude from these studies that quantitative information regarding the degree of inhomogeneity of V/Q for log normal distribution is available from direct calculations of inert gas retention and excretion data. Qualitative information is also available indicating the departure from log normality and the region toward which the distribution is skewed.

Biophysical Phenomena↗
PubMed2000

Training and overtraining markers in selected sport events.

PURPOSE: Varieties of symptoms are supposed to detect overtraining (OT). Besides the problems of diagnosis and analysis in elite athletes, a daily monitoring of training status takes place with measurement of the parameters serum urea (SU) and serum creatine kinase (CK); therefore, their meaningfulness will be examined, with special respect inter- and intra-individually. METHODS: Data were obtained from determinations during training from athletes in rowing and athletes of international level. RESULTS: For 6981 SU determinations (male, N = 717; female, N = 285), a slightly asymmetric normal distribution was found (male, 80%, 5-7 mmol x L(-1); female, 75%, 4-6 mmol x L(-1)). Values for women were approximately 1.5 mmol x L(-1) lower. Individual variability was enormous; there seems little point in setting fixed value as 8.3 mmol x L(-1) for men and 7.0 mmol x L(-1) for women as a critical limit for OT. CK has also been measured and evaluated in sports as an essential parameter for determination of muscular stress. Frequency distributions of CK in 2790 samples (male, N = 497; female, N = 350) presented an asymmetric normal distribution with distinct trend toward higher values being evident for the range between 100 and 250 U x L(-1). Conspicuously elevated values occurred in the ranges 250-350 U x L(-1) and 1000-2000 U x L(-1). Men's maximal values were 3000 U x L(-1) and 1150 U x L(-1) for women. Individual variability was enormous. Athletes with chronically low CK exhibited mainly low variability; those with chronically higher values exhibited considerable variability. CONCLUSIONS: Establishment of both parameters should be useful to determine individual baselines from a large number of samples. Determinations should be made at least every 3 d in standardized conditions. If a large increase is observed in combination with reduced exercise tolerance after a phase of exertion (2-4 d), then the possibility of a catabolic/metabolic activity or insufficient exercise tolerance becomes much more likely.

Biomarkers↗
PubMed1995

Application of the Poincaré plot to heart rate variability: a new measure of functional status in heart failure.

BACKGROUND: Conventional methods of quantifying heart rate variability using summary statistics have shown that decreased variability is associated with increased mortality in heart failure. However, many patients with heart failure have arrhythmias which make the 'raw' heart rate variability data less suitable for the use of summary statistical measures. AIMS: To examine the clinical potential of a new measure of heart rate variability data, presented by the Poincaré plot pattern, as an adjunct to the summary statistical measures of R-R interval variability. METHODS: We used the Poincaré plot pattern to display beat-to-beat heart rate variability data from a group of 23 patients with heart failure and compared them with data collected from 20 healthy age-matched control subjects. The data, which consists of 2000 consecutive R-R intervals, were gathered over 20-40 minutes while the subjects rested supine in a quiet darkened room. RESULTS: The morphological classification scheme proposed reflected the functional status of patients in heart failure. There was a significant difference (chi-square = 27.5, p < 0.0001) in the different pattern types between patients with NYHA Class I and II compared to patients with NYHA Class II and IV. All healthy subjects displayed a 'cluster' type of pattern characterised by normally distributed data. Sixteen of the 23 patients in heart failure also produced data which were normally distributed but the remaining seven produced data which required careful filtering to make them suitable for analysis using summary statistics, but which could be analysed by the Poincaré plot. CONCLUSIONS: The Poincaré plot pattern is a semi-quantitative tool which can be applied to the analysis of R-R interval data. It has potential advantages in that it allows assessment of data which are grossly non-Gaussian in distribution, and is a simple and easily implemented method which can be used in a clinical setting to augment the standard electrocardiogram to provide 'real time' visualisation of data.

Aged↗