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PubMed1990

Cortical glucose metabolism in Parkinson's and Alzheimer's disease.

Characteristic regional patterns of decreased cerebral glucose metabolism (rCMRG) have been described in a variety of neurodegenerative conditions associated with dementia. The present study was undertaken to determine whether the metabolic pattern in Parkinson's disease is altered by the presence of impaired cognitive function. Glucose metabolism was measured with positron emission tomography in 6 patients with Parkinson's disease and dementia (PDD), 8 patients with Parkinson's disease and normal cognition (PD), and 6 patients with Alzheimer's disease (AD). All AD patients subsequently had the diagnosis proven neuropathologically at autopsy. Correlation coefficients of the metabolic rates across 32 regions of interest were calculated between each pair of patients. Q-component analysis of the correlation matrix showed that the AD and PD groups formed two distinct clusters and that the PDD group had a metabolic pattern which was similar to that of the AD group. Comparison of standardized rCMRG values showed that the PDD group differed from the PD group in having significantly lower relative rCMRG in the left perirolandic and bilateral angular gyrus regions. There were no significant differences between the PDD and AD groups. These results suggest a similar pattern of cortical dysfunction in both Alzheimer's disease and in Parkinson's disease/dementia.

Aged↗

PubMed2001

Outcomes and patient-based hearing status in conductive hearing loss.

OBJECTIVES/HYPOTHESIS: To study hearing status and quality of life outcomes in patients with conductive hearing loss (CHL), and to develop a prognostic disease severity staging system for use in future clinical outcomes studies in CHL. STUDY DESIGN: Clinical outcomes research study in three stages: 1) Prospective development and psychometric validation of a disease-specific hearing status outcomes instrument for CHL. 2) Prospective observational outcomes study of patient-based hearing status and quality of life (QOL) outcomes after treatment of CHL. 3) Development of a prognostic disease-severity staging system to stratify patients into groups of similar treatment outcome. METHODS: Psychometric instrument validation: assessment of test-retest reliability, internal consistency reliability, content, construct and criterion validity, and responsiveness to change. Statistical assessment of the impact of CHL on patient-based hearing status and QOL, and the change in hearing status and QOL after treatment. Using data from the prospective study and multivariate regression, identification of pretreatment independent variables, which predict good outcome after treatment, and development of a severity staging system. RESULTS: Test-retest reliability (r >0.70) and internal consistency reliability (alpha >0.70) were adequate for both subscales of the hearing status instrument. Construct validity was demonstrated by adequate convergent/divergent validity with other health status instruments on multi-item multitrait correlation matrixes. Criterion validity was demonstrated using audiometric threshold data. Responsiveness to change was demonstrated using the standardized response mean after treatment (SRM = 0.40 and 0.61 for the two subscales). Emotional hearing status and social/situational hearing status improved significantly after treatment of CHL: emotional score, 31.1 to 56.6 (P < .001); social/situational score, 56.7 to 63.7 (P = .01). Mean QOL subscale scores for patients with CHL were not significantly different from healthy populations, and global QOL scores did not change significantly after treatment of CHL. Using proportional improvement in emotional hearing status as an outcome, we identified several pretreatment factors that predicted good outcome (i.e., larger proportional improvement): level of pretreatment emotional hearing status, presence of sensorineural component of HL, and etiology of CHL (otosclerosis vs. all other causes). Some hypothesized predictive independent factors, such as bilateral HL, audiometric threshold level, pretreatment functional status, employment status, age, and duration of HL, were not identified as significant predictors of outcome in the multivariate analysis. We constructed a prognostic disease severity staging system in which the three predictor variables were each given a score of 0 or 1, and these three scores were added to obtain the disease stage (stage 0, 1, 2, or 3). Higher disease stage indicated more severe disease or a lower proportional improvement in emotional hearing status after treatment. This staging system appropriately stratified patients into groups of similar outcome after treatment (P = .02) and has significant potential use for future outcomes research on CHL. CONCLUSIONS: We have developed and validated a patient-based hearing status outcomes instrument for use in CHL. We have measured hearing status and quality of life outcomes after treatment of CHL, and we have developed a prognostic disease severity staging system that predicts the improvement in emotional hearing status after treatment of CHL.

Adaptation, Physiological↗

PubMed1994

31P NMR in vivo study of the acute effects of different doses of gamma-radiation on rat brain phosphate metabolism.

Changes in relative levels of brain phosphates and intracellular pH at selected time intervals after total gamma-irradiation of a rat at a single dose of 6.5 or 300 Gy were studied by 31P NMR in vivo. Irradiation yielded only minor changes in the spectra. Irradiation at a dose of 6.5 Gy caused a reversible decrease in Pi and an alkaline pH shift of 0.2 units after day 1, with no change in ATP. The signal, which consisted of alpha-ATP, alpha-ADP, NAD+/NADH and diphosphodiesters, declined after day 6, possibly due to a fall in NAD+/NADH concentration. Irradiation at a dose of 300 Gy led to an increase in ATP from 10 to 13% of total phosphates after day 1. Homeostasis of brain energy metabolism was characterized by the Z-index (normalized sample correlation coefficients averaged over the correlation matrix for NMR-measured phosphomonoesters, Pi, pH, phosphocreatine, gamma-ATP+beta-ADP, alpha-ATP+alpha-ADP+NAD+/NADH+diphosphodiesters and beta-ATP). The Z value rose from -0.18 +/- 0.02 to -0.02 +/- 0.02 by day 6 or from -0.19 +/- 0.02 to -0.07 +/- 0.02 by day 1 after irradiation at a dose of 6.5 or 300 Gy, respectively. This may indicate a pathological state of brain energetics as a system and a decrease in its stability.

Animals↗

PubMed1984

A patient self-disclosure instrument.

Four studies in which a patient self-disclosure questionnaire was developed and tested are reported. The instrument was designed to include only content judged by both patients and clinicians as important. Three areas of patient difficulty in disclosing to a health care provider were measured: personal problems and feelings, responses to health care, and life style. Patient difficulty in disclosure was assessed by 21 7-point rating scales, 7 for each disclosure area; ratings were summed to obtain scores. A correlation matrix of the ratings of 216 patients was subjected to a three-factor principal components analysis with varimax rotation; the solution accounted for 59% of the total variance. High internal consistency and test re-test reliability for the total scale and subscales were obtained; Cronbach's alpha .82-.83, n = 214; r = .81-.87, n = 66. In separate tests of construct validity patient self-disclosure was shown to be influenced by locus of control and perception of clinician empathy, and to covary with heart rate changes.

Adolescent↗

PubMed2003

An integrated population-averaged approach to the design, analysis and sample size determination of cluster-unit trials.

While the mixed model approach to cluster randomization trials is relatively well developed, there has been less attention given to the design and analysis of population-averaged models for randomized and non-randomized cluster trials. We provide novel implementations of familiar methods to meet these needs. A design strategy that selects matching control communities based upon propensity scores, a statistical analysis plan for dichotomous outcomes based upon generalized estimating equations (GEE) with a design-based working correlation matrix, and new sample size formulae are applied to a large non-randomized study to reduce underage drinking. The statistical power calculations, based upon Wald tests for summary statistics, are special cases of a general power method for GEE.

Adolescent↗

PubMedDate not supplied

Parameters of mortality in human populations with widely varying life spans.

A three-component, competing-risk mortality model, developed for animal survival data, fits human life table data for all ages over a range of mean life spans from 16 to 74 years. The competing risks are a novel exponentially-decreasing hazard, dominant during immaturity; a constant hazard, dominant during adulthood; and an exponentially increasing Gompertzian hazard, dominant during senescence. By fitting the model to a specific life table using non-linear techniques, estimates of the five model parameters and their standard errors obtain; the proportion of deaths expected from each hazard alone may then be calculated. Preliminary analysis of 13 life tables indicates that for human populations under heavy stress, with very short mean life spans of about 20 years, the three hazard components account for roughly equal numbers of deaths; for modern populations, with mean life spans of about 75 years, nearly all deaths are due to the hazard of senescence. Factor analysis of the correlation matrix of parameter values for the 13 populations shows a two-factor structure. One factor involves only the multiplicative constants (initial values) of the three hazards, but not the hazard rates of change; the second factor involves only the parameter of the immaturity hazard and the rate of acceleration of the senescence hazard, but not the constant hazard nor the multiplicative constant (initial value) of the senescence hazard.

Adolescent↗

PubMed1993

Identity status and identity style: a replication study.

Seventy-four initial teacher preparation students completed a questionnaire assessing identity status development and identity style. A factor analysis using all of the EOM-EIS subscales and the four Identity Style subscales yielded five factors that explained 76.0% of the variability in the correlation matrix. Collectively, findings paralleled those of Berzonsky's (1988) work and support theoretical speculation concerning the process of identity formation.

Adolescent↗

PubMed2002

Genetic contributions to regional variability in human brain structure: methods and preliminary results.

Twin studies provide one approach for investigating and partitioning genetic and environmental contributions to phenotypic variability in human brain structure. Previous twin studies have found that cerebral volume, hemispheric volume, ventricular volume, and cortical gyral pattern variability were heritable. We investigated the contributions of genetic and environmental factors to both global (brain volume and lateral ventricular volume) and regional (parcellated gray matter) variability in brain structure. We examined MR images from 10 pairs of healthy monozygotic and 10 pairs of same-sex dizygotic twins. Regional gray matter volume was estimated by automated image segmentation, transformation to standard space, and parcellation using a digital atlas. Heritability was estimated by path analysis. Estimated heritability for brain volume variability was high (0.66; 95% confidence interval 0.17, 1.0) but the major effects on lateral ventricular volume variability were common and unique environmental factors. We constructed a map of regional brain heritability and found large genetic effects shared in common between several bilateral brain regions, particularly paralimbic structures and temporal-parietal neocortex. We tested three specific hypotheses with regard to the genetic control of brain variability: (i) that the strength of the genetic effect is related to gyral ontogenesis, (ii) that there is greater genetic control of left than of right hemisphere variability, and (iii) that random or fluctuating asymmetry in bilateral structures is not heritable. We found no evidence in support of the first two hypotheses, but our results were consistent with the third hypothesis. Finally, we used principal component (PC) analysis of the genetic correlation matrix, to identify systems of anatomically distributed gray matter regions which shared major genetic effects in common. Frontal and parietal neocortical areas loaded positively on the first PC; some paralimbic and limbic areas loaded negatively. Bilateral insula, some frontal regions, and temporal neocortical regions functionally specialized for audition and language loaded strongly on the second PC. We conclude that large samples are required for powerful investigation of genetic effects in imaging data from twins. However, these preliminary re. sults suggest that genetic effects on structure of the human brain are regionally variable and predominantly symmetric in paralimbic structures and lateral temporal cortex.

Algorithms↗

PubMed1987

A cognitive and associative memory.

By introducing a physiological constraint in the auto-correlation matrix memory, the system is found to acquire an ability in cognition i.e. the ability to identify an input pattern by its proximity to any one of the stored memories. The physiological constraint here is that the attribute of a given synapse (i.e. excitatory or inhibitory) is uniquely determined by the neuron it belongs. Thus the synaptic coupling is generally not symmetric. Analytical and numerical analyses revealed that the present model retrieves a memory if an input pattern is close to the pattern of the stored memories; if not, it gives a clear response by going into a special mode where almost all neurons are in the same state in each time step. This uniform mode may be stationary or periodic, depending on whether or not the number of the excitatory neurons exceeds the number of inhibitory neurons.

Association Learning↗

PubMed1987

Principal component analysis for the identification of pollution sources in mussel survey by trace metals.

Principal component analysis has been applied to analyze the correlation matrix obtained from a 8 X 43 data matrix. The 8 trace metals are Mn, Co, Ni, Cu, Zn, Cd, Hg, Pb, which are contained in the soft part of mussels (Mytilus galloprovincialis Lamarck). Mussels were sampled from two sites in the Gulf of Trieste. In both samples, 76-78% of the total variance is explained by the four principal components. The orthogonally rotated factor matrix indicates that Co and Ni are bonded to the first principal component and Cd and Pb to the first (site 2) or second principal component (site 1). The origin of trace metals in the soft part of mussels from the Gulf of Trieste is discussed.

Animals↗

PubMed1984

Principal component analysis as a tool for studying interdependences among trace metals in edible mussels from the Gulf of Trieste.

Principal component analysis has been applied to analyze the correlation matrix obtained from a (6 X 44) data matrix. The 6 trace metals are Co, Ni, Cu, Cd, Hg, and Pb, which are contained in the soft part of edible mussels (Mytilus galloprovincialis Lamarck) from a hatchery on the gulf of Trieste. In the space of "eigenvectors", the dimensions are reduced to 3 principal axes, which account for about 77% of the total variance. The unrotated factor matrix obtained by the principal components shows that Co, Ni and Cu are bonded to the first principal component, Cd and Pb to the second, Hg to the third. This picture is also assessed by the Varimax-rotated matrix and it is tentatively explained, at least in part, by considering the associations of the trace metals from various geographical sources.

Animals↗

PubMed1984

Values and therapy orientations of psychotherapy trainees: a twelve-year update.

Psychotherapy orientations, self-declared fortes in conducting therapy, and interpersonal values were studied among psychiatry residents and psychology interns in the late 1960s and early 1980s. A distinct pattern of psychotherapy orientations and fortes emerged which transcended professional backgrounds and proved stable across generations, despite some interactions between training and time. Subjects' professed areas of expertise were closely aligned with their beliefs about what methods are most effective in psychotherapy, and both these variables were significantly associated with their value profiles. The correlation matrix suggested a three-factor model of related psychotherapy and value orientations surrounding the three predominant modalities: insight, corrective emotional experiences, and learning. It was proposed that the data support the importance of value dimensions in contributing to psychotherapists' adoption of specific treatment strategies and their developing expertise in corresponding techniques.

Attitude↗

PubMed1988

Multivariate data analysis of sea waters and mussels in relation to pollution sources of trace elements.

The total concentration of Cu, Zn and Pb in surface sea waters from the Bay of Muggia (Gulf of Trieste, Northern Adriatic Sea) was determined by anodic stripping voltammetry. The association of these trace elements in relation to the known sources of pollution was discussed. The content of eight trace elements (Mn, Co, Ni, Cu, Zn, Cd, Hg, Pb) in the soft part of mussels (Mytilus galloprovincialis Lamarck) is also considered. The wild molluscs were sampled in the harbour of Trieste, in the proximity of an important city sewer. Principal component analysis was used to analyse the correlation matrix obtained from an 8 x 43 data matrix after a logarithmic transformation of the concentration variables. Eight variables were reduced to four principal components, which explained 80% of the total variance. The orthogonally rotated factor matrix shows that Co, Ni, Cd, and Pb are associated with the first principal component, Cu and Zn to the second, Hg to the third and Mn to the fourth principal component. The results of this multivariate data analysis are compared with those already obtained from two sampling sites in the Bay of Muggia and the origin of some trace metals in the soft part of mussels from the Gulf of Trieste is discussed.

Analysis of Variance↗

PubMed1994

Measurement of CO2 response with the breath-by-breath automatic acquisition of the breathing pattern and occlusion pressure.

OBJECTIVE: Our objective is to present a methodology for the automated acquisition and storage of BP and P0.1 during a CO2 rebreathing test. METHODS: The system consists of a microcomputer with additional circuits and an automatic electronically controlled valve to occlude the inspiratory airway. Data collection and data processing are separate programs. Airway pressure and flow are digitized at a 100-Hz rate, while PETCO2 is determined and P0.1 is measured on a breath-by-breath basis. Off-line processing calculates the BP variables, generates a correlation matrix (VE/PETCO2, TTOT/PETCO2, TI/PETCO2, TE/PETCO2, [VT/TI]/PETCO2, [TI/TTOT]/PETCO2, P0.1/PETCO2), and edits graphic data. The accuracy of the volume and pressure measurements was tested by comparing known volumes provided by a syringe (n = 100) and a series of pressures controlled by a water manometer (n = 41) on the one hand, with volumes and pressures measured by the device. The accuracy of the time intervals and P0.1 was assessed by comparing in 10 healthy subjects the values measured manually on a graphic recording with those provided by the device (n = 170). RESULTS: Volumes:Vmeasured = 0.99 x Vcontrolled, r = 0.99, p < 0.001. Pressures:Pmeasured = 0.97 x Pcontrolled + 0.09, r = 0.98, p < 0.001. Inspiratory time:TIautomatic = 0.91 x TIgraphic + 0.22, r = 0.93, p < 0.001. Expiratory time:TEautomatic = 0.93 x TEgraphic + 0.34, r = 0.95, p < 0.001. Occlusion pressure:P0.1automatic = 0.95 x P0.1graphic + 0.62, r = 0.94, p < 0.001. Reproducibility was assumed to be represented by the intraindividual coefficient of variation of the CO2 response. The comparison of an automatic breath-to-breath method with a graphic manual recording revealed significantly less variability with the former (VE/PETCO2: 15.2 +/- 4.5% vs 22.5 +/- 6.3%, p < 0.01; P0.1/PETCO2:8.3 +/- 4.3% vs 19.7 +/- 7.2%, p < 0.001; [VT/TI]/PETCO2:9.1 +/- 3.5% vs 14.5 +/- 5.3%, p < 0.05). CONCLUSION: Our automated acquisition and storage of waveforms and breath-by-breath determination of BP and P0.1 provide an easy and thorough analysis of the respiratory response to CO2 and decrease the variability of the results.

Anesthesia, Closed-Circuit↗

PubMed1989

Relative positions of some epitopes on carcinoembryonic antigen.

To investigate whether anti-(carcinoembryonic antigen) monoclonal antibodies (mAb) react with single or repeated epitopes, sandwich radioimmunoassays in homologous and heterologous combinations were performed. Four mAb (I-27, I-47, II-17 and to some degree II-16) gave homologous binding while two mAb (I-38S1 and II-10) did not. Taken together with previous immunoprecipitation studies we conclude that all these mAb except II-10 react with repeated epitopes. The relative positions of the epitopes recognized by these mAb and of three additional mAb (II-6, II-7 and CB-CEA-1) were investigated using a plate antibody competition test with enzyme-labelled carcinoembryonic antigen (CEA). mAb I-38S1, II-6, II-7, II-10, II-16 and CB-CEA-1 were mutually cross-reactive, and were classified as belonging to one epitope group. mAb I-27 and I-47 fell outside this group and did not interfere with the binding of CEA conjugate to mAb II-17 either. They therefore represent a second epitope group. mAb II-17 showed no interference with the binding of CEA to any of the other mAb and must therefore represent a third epitope group. The slopes of the plate antibody competition curves were used for calculation of a correlation matrix, which in turn was used to depict the relative positions of the epitopes recognized by the mAb in the large group.

Antibodies, Monoclonal↗

PubMed2001

Analysis of forced expired volume signals using multi-exponential functions.

Patients with pulmonary disease are often unable to complete forced expiration manoeuvres. The aim of the study is to evaluate whether forced vital capacity (FVC), the volume exhaled at the end of completed forced expiration, can be estimated by extrapolating volume-time curves obtained from uncompleted manoeuvres. The suitability of mono-, bi-, and tri-exponential functions to characterise complete volume-time curves from 50 subjects is investigated. Mono-exponential modelling is insufficient, whereas bi-exponential fitting yields an adequate description for 47 data sets. Tri-exponential models lead to overfitting in all but three cases (normalised sum of least squares: 50.2 +/- 34.5 for mono-, 2.76 +/- 4.11 for bi-, 2.74 +/- 4.19 for tri-exponential modelling; condition number of the correlation matrix: 1.0025 +/- 0.0004 for mono-, 1.08 +/- 0.08 for bi-, 34.7 +/- 100.1 for tri-exponential fitting (mean +/- SD)). Thus, FVC is estimated by the extrapolation of 27 uncompleted spirograms using bi- or tri-exponential models, depending on their accordance with measured data and on the identifiability of their parameters. This algorithm yields unbiased estimates (difference from measured inspiratory vital capacity: 0.01 +/- 0.21 L). This method can be used for investigation of the lung function of subjects who cannot complete the forced expiration manoeuvre.

Adolescent↗

PubMed2004

Correlation-based decomposition of surface electromyograms at low contraction forces.

The paper studies a surface electromyogram (SEMG) decomposition technique suitable for identification of complete motor unit (MU) firing patterns and their motor unit action potentials (MUAPs) during low-level isometric voluntary muscle contractions. The algorithm was based on a correlation matrix of measurements, assumed unsynchronised (uncorrelated) MU firings, exhibited a very low computational complexity and resolved the superimposition of MUAPs. A separation index was defined that identified the time instants of an MU's activation and was eventually used for reconstruction of a complete MU innervation pulse train. In contrast with other decomposition techniques, the proposed approach worked well also when the number of active MUs was slightly underestimated, if the MU firing patterns partly overlapped and if the measurements were noisy. The results on synthetic SEMG show 100% accuracy in the detection of innervation pulses down to a signal-to-noise ratio (SNR) of 10 dB, and 93+/-4.6% (mean+/-standard deviation) accuracy with 0 dB additive noise. In the case of real SEMG, recorded with an array of 61 electrodes from biceps brachii of five subjects at 10% maximum voluntary contraction, seven active MUs with a mean firing rate of 14.1 Hz were identified on average.

Action Potentials↗

PubMedDate not supplied

Breastfeeding practices in Ethiopian women in southern California.

A retrospective study on the breastfeeding was carried out on selected 45 Ethiopian immigrant women living in the Los Angeles and San Diego areas (mean = 41 months; range 10-84 months). In-depth interviews were conducted to gather information on breastfeeding habits and a detailed analysis was made of the factors leading to the cessation of breastfeeding. The mean duration of breastfeeding in this sample was 4.2 +/- 1.1 months (range 3.0-5.7 months); and a non significant association was found between the length of residence in USA and the duration of breastfeeding (r = 0.189; 0.001 less than p less than 0.01 Pearson Correlation Matrix). Mothers breastfeeding less than four months (N = 27) were compared to mothers who breastfed longer than four months (N = 18). A statistically significant association was found between the duration of breastfeeding and the following variables: mother's level of education (X2 = 20.12 p less than 0.005, df = 1), source of income (X2 = 13.46, p = 0.001, df = 1)' and the availability of free sample formula form the hospital (X2 = 4.46 p = 0.035, df = 1). The most common cited reasons for stopping breastfeeding were mother's employment (40%), and mother's lack of milk (32%). Data suggest here that the Ethiopian immigrant women in this selected sample are not following the trends towards breastfeeding in the United States.

Adult↗