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PubMed2001

Comparative binding energy (COMBINE) analysis of human neutrophil elastase inhibition by pyridone-containing trifluoromethylketones.

The complexes of human neutrophil elastase with a series of 40 N3-substituted trifluoromethylketone-based pyridone inhibitors have been modelled. The series spans three orders of magnitude in inhibition constants despite the fact that it was originally developed in an attempt to improve the oral activity of a lead compound. Ligand-receptor interaction energies calculated using molecular mechanics did not correlate well with the experimental activities. A good correlation with activity was found, however, when a COMBINE analysis of the same data was carried out, which allowed a quantitative interpretation of the modelled complexes. The essence of this method is to partition the ligand-receptor interaction energies into individual residue-based van der Waals and electrostatic contributions, and to subject the resulting energy matrix to partial least squares analysis. Incorporation of two additional descriptors representing the electrostatic energy contributions to the partial desolvation of both the receptor and the ligands improved the QSAR model, as did the replacement of the distance-dependent electrostatic contributions with solvent-screened electrostatic interactions calculated by numerically solving the Poisson-Boltzmann equation. The model was validated both internally (cross-validation) and externally, using a set of twelve 6-phenyl-pyridopyrimidine analogs. The analysis reveals the subtle interplay of binding forces which occurs within the enzyme active site and provides objective information that can be interpreted in the light of the receptor structure. This information, gained from a series of real compounds, can be easily translated into 3D real or virtual database queries in the search for more active derivatives.

Humans↗
PubMed2006

International Physical Activity Questionnaire: Validity against fitness.

PURPOSE: This study was conducted to criterion-validate the short format of International Physical Activity Questionnaire (IPAQ) against health-related fitness. METHODS: Participants included 951 men, aged 21-43 yr. VO2max by ergometer was used to measure cardiorespiratory fitness. Muscular fitness tests included the number of sit-ups, push-ups, and squats performed during 60 s. Physical activity was assessed from IPAQ by categories for health (health-enhancing physical activity (HEPA)) and by calculating total and vigorous MET-hours per week. The participants were classified in five groups of almost equal size by the IPAQ outcomes. Moreover, the frequency of vigorous activity was assessed by one precoded question (single-item question on leisure-time vigorous physical activity (SIVAQ)). RESULTS: The mean fitness improved from the first through the fourth IPAQ group. VO2max in the most active IPAQ group, however, was lower than in the fourth group (P < 0.05), both with HEPA categories and vigorous METs as the outcome. In contrast, the weekly frequency of vigorous physical activity showed a positive association with fitness through all six categories. The 65 sedentary (according to SIVAQ) and unfit individuals who belonged to the highest 20% (by IPAQ total METs) were older (30.6 +/- 5.1 vs 28.9 +/- 3.8, P = 0.02), more obese (waist 93 +/- 12 vs 89 +/- 10 cm), more often current smokers (59.4 vs 42.0%; P = 0.03), and less educated (<12 yr of education 70.8 vs 52.0%; P = 0.02), compared with the others in the highest IPAQ group. CONCLUSIONS: Almost 10% of young men had poor fitness and apparently low physical activity, but they reported very high physical activity by IPAQ. An evident need therefore exists to develop IPAQ further to solve the apparent overreporting by a considerable proportion of sedentary individuals.

Adult↗
PubMed2002

Psychometric properties of the statistics anxiety rating scale.

The Statistics Anxiety Rating Scale has 51 items, each scored on a 5-point rating scale to measure statistics anxiety with six subscales, Worth of Statistics, Interpretation Anxiety, Test and Class Anxiety, Computational Self-concept, Fear of Asking for Help, and Fear of Statistics Teachers. Psychometric properties included analyses of construct and concurrent validities an internal consistency and test-retest reliability. 221 college students (74% women; M age=28 yr.) in elementary statistics courses at several southwestern state universities participated. The findings are consistent with previous reports and indicate adequate concurrent validity, internal consistency, and split-half reliability, but for construct validity confirmatory factor analysis yielded marginal support.

Adolescent↗
PubMed2005

Sources of validity evidence for an internal medicine student evaluation system: an evaluative study of assessment methods.

BACKGROUND: Medical students' final clinical grades in internal medicine are based on the results of multiple assessments that reflect not only the students' knowledge, but also their skills and attitudes. OBJECTIVE: To examine the sources of validity evidence for internal medicine final assessment results comprising scores from 3 evaluations and 2 examinations. METHODS: The final assessment scores of 8 cohorts of Year 4 medical students in a 6-year undergraduate programme were analysed. The final assessment scores consisted of scores in ward evaluations (WEs), preceptor evaluations (PREs), outpatient clinic evaluations (OPCs), general knowledge and problem-solving multiple-choice questions (MCQs), and objective structured clinical examinations (OSCEs). Sources of validity evidence examined were content, response process, internal structure, relationship to other variables, and consequences. RESULTS: The median generalisability coefficient of the OSCEs was 0.62. The internal consistency reliability of the MCQs was 0.84. Scores for OSCEs correlated well with WE, PRE and MCQ scores with observed (disattenuated) correlation of 0.36 (0.77), 0.33 (0.71) and 0.48 (0.69), respectively. Scores for WEs and PREs correlated better with OSCE than MCQ scores. Sources of validity evidence including content, response process, internal structure and relationship to other variables were shown for most components. CONCLUSION: There is sufficient validity evidence to support the utilisation of various types of assessment scores for final clinical grades at the end of an internal medicine rotation. Validity evidence should be examined for any final student evaluation system in order to establish the meaningfulness of the student assessment scores.

Clinical Competence↗
PubMedDate not supplied

General melting point prediction based on a diverse compound data set and artificial neural networks.

We report the development of a robust and general model for the prediction of melting points. It is based on a diverse data set of 4173 compounds and employs a large number of 2D and 3D descriptors to capture molecular physicochemical and other graph-based properties. Dimensionality reduction is performed by principal component analysis, while a fully connected feed-forward back-propagation artificial neural network is employed for model generation. The melting point is a fundamental physicochemical property of a molecule that is controlled by both single-molecule properties and intermolecular interactions due to packing in the solid state. Thus, it is difficult to predict, and previously only melting point models for clearly defined and smaller compound sets have been developed. Here we derive the first general model that covers a comparatively large and relevant part of organic chemical space. The final model is based on 2D descriptors, which are found to contain more relevant information than the 3D descriptors calculated. Internal random validation of the model achieves a correlation coefficient of R(2) = 0.661 with an average absolute error of 37.6 degrees C. The model is internally consistent with a correlation coefficient of the test set of Q(2) = 0.658 (average absolute error 38.2 degrees C) and a correlation coefficient of the internal validation set of Q(2) = 0.645 (average absolute error 39.8 degrees C). Additional validation was performed on an external drug data set consisting of 277 compounds. On this external data set a correlation coefficient of Q(2) = 0.662 (average absolute error 32.6 degrees C) was achieved, showing ability of the model to generalize. Compared to an earlier model for the prediction of melting points of druglike compounds our model exhibits slightly improved performance, despite the much larger chemical space covered. The remaining model error is due to molecular properties that are not captured using single-molecule based descriptors, namely both inter- and intramolecular interactions and crystal packing, for which examples of and reasons for outliers are given.

Journal Article↗
PubMed2003

Developing an empirical typology for regular exercise.

BACKGROUND: Tailored interventions require the identification of distinct homogenous subgroups that will benefit from different intervention materials. One way to identify such subgroups is to use cluster analysis to identify an empirical typology. METHODS: A sample of 346 adults completed surveys through a telephone interview that included questions related to participating in regular exercise. The three variables used in the cluster analysis were the Pros of Exercise, the Cons of Exercise, and Exercise Self-Efficacy. RESULTS: Six resulting clusters were labeled Disengaged, Immotive, Relapse Risk, Early Action, Maintainers, and Habituated. A series of analyses tested the internal and external validity of the typology. The internal validity test revealed that four of the clusters demonstrated high stability and replicability, while the Relapse Risk and Early Action clusters were less stable. Differences among clusters on self-reported exercise behavior and a strong association with stage of change for regular exercise provided external validity evidence of the typology. CONCLUSIONS: The resulting typology reflects a range of motivational patterns that are likely to be responsive to different types of messages and strategies regarding adoption and maintenance of regular exercise. The typology also generates a number of hypotheses about the identified clusters that can be empirically tested in further studies.

Adult↗
PubMed2005

Reliability and validity of the Geriatric Depression Scale in depression in Parkinson's disease.

The objective of this study was to investigate reliability and validity of the self rated 30 item Geriatric Depression Scale (GDS) in screening and diagnosis of depression in Parkinson's disease (PD). The study sample comprised 109 non-demented patients with PD admitted to the movement disorders outpatient unit. The reference diagnosis of depression was made according to DSM-IV criteria. Discriminant validity and internal consistency of the total scale were studied. Sensitivity, specificity, and positive and negative predictive values (PPV and NPV) were calculated for different cutoff scores. Receiver operating characteristics (ROC) analysis was also carried out. The sample comprised 56 patients with and 53 without depression. In the discriminant validity analysis, the mean total GDS score of subjects with depression was significantly higher compared with those without depression. The Cronbach's alpha score was 0.92 and the split half correlation coefficient 0.91. The cutoff score of 13/14 provided the highest sum of sensitivity and specificity level. The sensitivity of this cutoff score was 0.78 and specificity 0.85, while PPV was 0.84 and NPV 0.79. The area under the curve value in the ROC analysis was 0.891. Sensitivity and specificity analysis showed that cutoff scores of 8/9 or 9/10 could be useful for screening and 14/15 or 15/16 for diagnostic purposes. This study showed that the 30 item GDS, with its high discriminant validity, internal consistency, and reasonably clear cutoff scores, could be a useful screening or diagnostic self rated depression scale in patients with PD.

Adult↗
PubMed2006

Internal consistency, stability, and validity of the spinal cord injury version of the multidimensional pain inventory.

OBJECTIVE: To evaluate the internal consistency, stability, and construct validity of a spinal cord injury (SCI) version of the Multidimensional Pain Inventory (MPI-SCI). DESIGN: Interview. SETTING: Veterans Affairs medical center and university-based institute. PARTICIPANTS: Community sample of persons with SCI and chronic pain (N=161). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE: The MPI-SCI. RESULTS: The internal consistency of the MPI-SCI subscales ranged from fair (.60) for affective distress to substantial (.94) for pain interference with activities. The subscales of the MPI-SCI (ie, life interference [r=.81], affective distress [r=.71], solicitous responses [r=.86], distracting responses [r=.85], general activity [r=.69], pain interference with activities [r=.78], pain severity [r=.69], negative responses [r=.69]) showed adequate stability. In contrast, the stability of the support (r=.59) and the life control subscales (r=.31) was unacceptably low. All MPI-SCI subscales with the exception of the perceived responses by significant others subscales showed good convergent, discriminant, and concurrent validity. CONCLUSIONS: The MPI-SCI appears to be a reasonable measure for evaluating chronic pain impact after SCI. In clinical trials, however, supplementary instruments should be included to assess changes in affect, social support, and perceptions of life control.

Adult↗
PubMed2005

Preliminary study to evaluate the validity of the mini-mental state examination in a normal population in Turkey.

Although the Mini-Mental State Examination (MMSE) is widely used in clinical practice, normative scores for a healthy population have not been documented in Turkey. The aim in this study was to validate the MMSE in a healthy population and to provide normal scores. Internal construct validity of the Turkish version of MMSE among a preliminary sample of 406 normal people was assessed by Rasch unidimensional measurement model. Scores of the normal sample varied according to age and education but not according to sex. The data derived from this sample showed poor fit to the Rasch model (mean item fit, -2.082, SD 3.022). Only four of 11 items met model expectations. There was also differential item functioning by education and age for most items. Thus the internal construct validity of the Turkish MMSE in a normative sample could not be demonstrated by Rasch analysis. The scale failed modern psychometric criteria for scalability. We would therefore suggest other large normative MMSE data sets to be tested in terms of internal construct validity. If these findings are replicated, the validity of MMSE norms and their consequent use in clinical practice should be reconsidered.

Adolescent↗
PubMed2005

Epidemiology of prolapse and incontinence questionnaire: validation of a new epidemiologic survey.

The epidemiology of prolapse and incontinence questionnaire (EPIQ) was developed to screen for female pelvic floor disorders (PFD). Content and face validity, reliability, internal consistency and criterion validity of the EPIQ to detect the presence of pelvic organ prolapse (POP), stress urinary incontinence (SUI), overactive bladder (OAB) and anal incontinence (AI) is presented. Cronbach's alpha; Spearman's, kappa, intraclass correlations, factor analysis and Chi-Squared tests were used for analysis. Questions related to PFD proved internally consistent (alpha = 0.91) and reproducible (correlations >0.70) for all but three items on the EPIQ. Positive and negative predictive values of the EPIQ to detect PFD were: POP = 76% and 97%, SUI = 88% and 87%, OAB = 77% and 90% and AI = 61% and 91% respectively. EPIQ is a psychometrically validated screening instrument that may identify women at high risk of having pelvic floor disorders in large undiagnosed populations.

Adult↗
PubMed1990

The internal consistency and concurrent validity of a Spanish translation of the Child Behavior Checklist.

The Child Behavior Checklist's applicability to a Hispanic sample was assessed by an examination of the instrument's internal consistency and concurrent validity. The CBCL and TRF were administered to a community sample representative of children of Puerto Rico aged 4 to 16. Cronbach's alpha was used to assess the internal consistency of empirically derived scales. The relation of CBCL and TRF scores to clinical diagnosis, adaptive functioning, and need for services served as indicators of the concurrent validity of the instrument's Spanish version. The results indicate that the total behavior problem scores on the instruments are good continuous measures of maladjustment for children in Puerto Rico. A child with high values on the scales has a high probability of being classified as a case by a psychiatrist. High levels of internal consistency were found in most subscales. Only scales comprising low prevalence problems showed poor internal consistency.

Adolescent↗
PubMed2006

Linear QSAR regression models for the prediction of bioconcentration factors by physicochemical properties and structural theoretical molecular descriptors.

The development of QSAR models useful for the prediction of fish bioconcentration factor (BCF) for a wide range of different chemical classes is crucial for the assessment and prioritisation of potentially persistent bioaccumulative and toxic substances. In this study we present QSAR models for BCF developed on a wide range of chemical structural classes of environmental and toxicological interest (such as dyes and various chlorinated and brominated compounds). The aim is to provide valid QSAR models, statistically validated for predictivity, for the prediction of BCF in general, but also for problematical chemical classes such as highly hydrophobic chemicals. Several descriptors, calculated by different commercially available software packages, have been employed in order to take into account relevant information provided by physicochemical properties (octanol/water partition coefficient and water solubility) and molecular features (structural and quantum-chemical molecular descriptors). The best descriptor subsets for the models were selected using the Genetic Algorithm-Variable Subset Selection strategy (GA-VSS) and calculations were performed by ordinary least squares regression. Starting from a data set of 640 compounds (logK(ow) range from -2.34 to 12.66), we developed linear QSARs, firstly for a data set of 620 compounds (logK(ow) range from -2.34 to 10.35) and secondly specifically for 87 highly hydrophobic chemicals (logK(ow) range from 6.00 to 10.35). All these models have been statistically validated (both internally by cross-validation and bootstrap and externally, by "a priori" splitting of available data by Kohonen Map-ANN in training and prediction sets) and their structural chemical domain has been verified by the leverage approach.

Animals↗