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PubMed1991

Reliability and validity of the objective structured clinical examination in paediatrics.

The assessment of clinical competence has traditionally been carried out through standard evaluations such as multiple choice question and bedside oral examinations. The attributes which constitute clinical competence are multidimensional, and we have modified the objective structured clinical examination (OSCE) to measure these various competencies. We have evaluated the validity and reliability of the OSCE in a paediatric clinical clerkship. We divided the examination into the four components of competence (clinical skills, problem-solving, knowledge, and patient management) and evaluated the performance of 77 fourth-year medical students. The skill and content domains of the OSCE were carefully defined, agreed upon, sampled and reproduced. This qualitative evaluation of the examination was both adequate and appropriate. We achieved both acceptable interstation and intertask reliability. When correlated with concurrent methods of evaluation we found the OSCE to be an accurate measure of paediatric knowledge and patient management skills. The OSCE did not correlate, however, with traditional measures of clinical skills including history-taking and physical examination. Our OSCE, as outlined, offers an objective means of identifying weaknesses and strengths in specific areas of clinical competence and is therefore an important addition to the traditional tools of evaluation.

Clinical Clerkship↗
PubMed1991

The solution structures of Escherichia coli trp repressor and trp aporepressor at an intermediate resolution.

We have determined the solution structures and examined the dynamics of the Escherichia coli trp repressor (a 25-kDa dimer), with and without the co-repressor L-tryptophan, from NMR data. This is the largest protein structure thus far determined by NMR. To obtain a set of data sufficient for a structure determination it was essential to resort to isotopic spectral editing. Line broadening observed in this molecular mass range precludes for the most part the measurement of coupling constants and stereospecific assignments, with the inevitable result that the attainable resolution of the final structure will be somewhat lower than the resolution reported for smaller proteins and peptides. Nevertheless the general topology of the protein can be deduced from the subsets of NOEs defining the secondary and tertiary structure, providing a basis for further refinement using the full set of NOEs and energy minimization. We report here (a) an intermediate resolution structure that can be deduced from NMR data, covalent, angular and van-der-Waals constraints only, without resort to detailed energy calculations, and (b) the limits of uncertainty within which this structure is valid. An examination of these structures combined with backbone amide exchange data shows that even at this resolution three important conclusions can be drawn: (a) the protein structure changes upon binding tryptophan; (b) the putative DNA binding region is much more flexible than the core of the molecule, with backbone amide proton exchange rates 1000 times faster than in the core; (c) the binding of tryptophan stabilizes the repressor molecule, which is reflected in both the appearance of additional NOEs, and in the slowing of backbone proton exchange rates by factors of 3-10. Sequence-specific 1H-NMR assignments and the secondary structure of the holopressor (L-tryptophan-bound form) have been reported previously [C. H. Arrowsmith, R. Pachter, R. B. Altman, S. B. Iyer & O. Jardetzky (1990) Biochemistry 29, 6332-6341]. Those for the trp aporepressor (L-tryptophan-free form), made using the same methods and conditions as described in the cited paper, are reported here. The secondary structure of the aporepressor was calculated from sequential and medium-range NOEs and is the same as reported for the holorepressor except that helix E is shorter. The tertiary solution structures for both forms of the repressor were calculated from long-range NOE data.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1992

Obsessions and compulsions: dimensional structure, reliability, convergent and divergent validity of the Padua Inventory.

This study presents data on dimensional structure, reliability, convergent and divergent validity of the Padua Inventory (PI). In a sample (n = 430) of normal Dutch subjects. The dimensional structure and the strength of the factors were comparable to those found in the Italian sample. The reliability of the PI was found to be satisfactory. As hypothesized substantial correlations were found between the PI and related scales of the Maudsley Obsessive-Compulsive Inventory (MOCI) and between the PI and the subscales Sensitivity, Hostility and Depression of the revised version of the Symptom Checklist. Low correlations were found between the PI on the one side and the Eysenck Personality Questionnaire revised Extraversion, Psychoticism and Social Desirability scale on the other side. Finally, the mean score of the PI differs across the Italian, American and Dutch samples. This is of theoretical interest and deserves further study.

Adolescent↗
PubMedDate not supplied

Age differences in personality structure revisited: Studies in validity, stability, and change.

Construct validity and longitudinal stability evidence for three cluster dimensions of personality identified as Anxiety, Extraversion, and Openness is examined in a sample of adult males. Correlations with Allport-Vernon-Lindsay Value scales, Cornell Medical Index scores, Eysenck E and N scales, and factors from the SVIB are presented in support of the interpretation of the three clusters. Nine-year longitudinal evidence of stability is presented for Anxiety and Extraversion scores. Previous evidence for change in the structure of Openness to Experience is reconsidered in the light of eleven-year longitudinal data. While the earlier structural differences were not longitudinally replicated, a pattern of external correlates provided evidence for validity of an Openness dimension. Finally, the structural approach to personality development is illustrated by examining the differing relations between field-dependence and tendermindedness in younger and older men.

Adult↗
PubMed1994

[Validity of the Brief Psychiatric Rating Scale].

The internal structure and validity of terms used in the Brief Psychiatric Rating Scale (Overall and Gorham, 1962) was analyzed. The data which had been gained at the entrance examination of 1557 inpatients with the diagnosis according to ICD-9 (schizophrenia simplex, schizophrenia paranoids, schizoaffective disease depressive type, schizoaffective disease manic type, manic-depressive disease manic phase, manic-depressive disease depressive phase) were processed using stepwise discriminant analysis (SDA). Three-dimensional space defined by SDA provided a sufficient frame of relations for the majority of diagnostic groups. Incomplete component analysis justified the assumption of a relatively stabile internal structure of the method. The findings allow to recommend the Czech version of the scale for the purpose of description of psychic impairments in psychiatry.

Adolescent↗
PubMed1994

The Children's Headache Assessment Scale (CHAS): factor structure and psychometric properties.

This study investigated the content validity, factor structure, and psychometric properties of the Children's Headache Assessment Scale (CHAS), a parent rating scale for identifying environmental variables associated with pediatric headache. In Study 1, input from physicians and psychologists was obtained to develop a revised set of 44 items receiving high endorsement. In Study 2, the questionnaire was administered to parents of 92 child headache sufferers, ages 6-16, and readministered 2 weeks later. An exploratory factor analysis revealed five factors (Disruptive Impact, Social Consequences, Stress Antecedents, Physical Antecedents and Quiet Coping, and Prescription Medication Use) that reflect distinct environmental concomitants of childhood headache. Scale reliabilities (alpha, .64-.82) indicate acceptable internal consistency, and test-retest reliabilities indicate relatively stable factors and items. High scores on the Disruptive Impact factor were associated with more severe, lengthy, and infrequent headache occurrence, lending initial support for the validity of this factor. Overall, the findings support the clinical and research utility of the CHAS in behavioral treatment of childhood headache.

Adolescent↗
PubMed1984

A simplistic approach to structural dysplasia assessment: description and validation.

The purpose of this study was to formulate a simplistic method of assessing human structural dysplasia and to validate a classification system that would objectively categorize the type and extent of such dysplasia through the use of indices. Anthropometric measurements were taken from a sample of 222 male college students, length/breadth ratios were formulated, and upper/lower body classifications were made in terms of type and subtype dysplasia. Correlation validation results were highly significant. Body composition data information was also provided for descriptive purposes.

Adipose Tissue↗
PubMed1977

Raman spectral studies of nucleic acids. XVII. Conformational structures of polyinosinic acid.

Laser-Raman spectra of poly(rI) show the formation of an ordered complex in aqueous solutions of high ionic strength. This structure exhibits the A-helix geometry, contains stacked bases and is apparently stabilized by specific hydrogen bonding involving hypoxanthine C6=0 groups. Thermal dissociation of the poly(rI) complex (Tm=45 degrees C) yields single-stranded and disordered poly (RI) chains. A disordered structure also occurs for poly (rI) in aqueous solutions of low ionic strength. In oriented films, poly (rI) forms an ordered structure probably the same as that which occurs in solutions of high ionic strength. Raman intensities measured at 815 and 1100 cm-1 in spectra of poly (rI) and poly (rU)-poly (rA)-poly(rU) indicate that the correlation previously established for single- and double-stranded ribopolymer structures is valid also for these multi-stranded structures. X-ray diffraction and model-building studies confirm the A-helix structure.

Deuterium↗
PubMedDate not supplied

Taxonomic validation: an overview.

A valid taxonomy legitimizes the elements that make up the taxonomy and increases trust in its generalizability and predictability. There is a concern that the NANDA Taxonomy is not a valid taxonomic structure. Despite on-going work to validate individual nursing diagnoses, there is little research that focuses on validation of groups of diagnoses (taxons) within the NANDA taxonomy. This last article in a series of four will familiarize the readers with why, what, and how a taxonomy of nursing diagnoses can be validated. This article highlights assessment of the validity and reliability of a taxonomy, compares the process of taxonomic validation to the research process, and explores examples of validation design.

Cluster Analysis↗
PubMed1982

Cross-validation of the factor structure of the McGill Pain Questionnaire.

Low back pain patients' responses to the McGill Pain Questionnaire (MPQ) were factor analyzed using the principal factor method and direct oblique rotation procedures. Four factors were extracted that accounted for 55% of the total variance. Coefficients of congruence were computed in order to relate the current factors with those extracted in a previous factor analytic investigation. The results provided positive evidence that the sensory pressure, evaluative, and affective-sensory factors that were previously identified are stable dimensions underlying the MPQ responses of low back pain patients. However, it is necessary to conduct further cross-validation studies using patients from a wide variety of treatment settings.

Adolescent↗
PubMed1992

The importance of comparative studies and ecological validity for understanding hippocampal structure and cognitive function.

Building from the premise that hippocampal cognitive function has been molded by natural selection under natural environmental conditions, it is argued that traditional laboratory studies likely do not reveal the richness and complexity of hippocampal function. Research on the role of the hippocampal formation in the navigational behavior of homing pigeons is offered as an example to illustrate the advantages of using an ecological approach to understand hippocampal function. It is further proposed that dissimilarities in hippocampal anatomy, physiology, and neurochemistry found between species reflect species differences in the range of functions served by the hippocampal formation, as well as possibly the molecular and cellular mechanisms that support such functions. These differences notwithstanding, it is suggested that, from an evolutionary perspective, the primary function of the hippocampal formation is a role in some aspect of spatial cognition. Dissimilarities in hippocampal structure and function among extant species are viewed as resulting from differences in evolutionary selective pressure and evolutionary history.

Animals↗
PubMed1994

The twenty-item Toronto Alexithymia Scale--I. Item selection and cross-validation of the factor structure.

Addressing shortcomings of the self-report Toronto Alexithymia Scale (TAS), two studies were conducted to reconstruct the item domain of the scale. The first study resulted in the development of a new twenty-item version of the scale--the TAS-20. The TAS-20 demonstrated good internal consistency and test-retest reliability, and a three-factor structure theoretically congruent with the alexithymia construct. The stability and replicability of this three-factor structure were demonstrated in the second study with both clinical and nonclinical populations by the use of confirmatory factor analysis.

Adult↗
PubMed1990

Dimensions of pain-related cognitive coping: cross-validation of the factor structure of the Coping Strategy Questionnaire.

Previous research has demonstrated a relationship between cognitive pain coping activity and adjustment in pain patients. The empirically derived dimensions of coping activity, as measured by scales from the Coping Strategy Questionnaire (CSQ), however, have varied across investigations. The purpose of this investigation was to determine both the content and number of dimensions of the CSQ and to explore the potential moderating influence that sociodemographic and patient history variables may have on the latent structure of the CSQ. A total of 620 patients from 5 different chronic pain patient samples were used to assess the generalizability of the dimensions across samples. Confirmatory factor analytic procedures identified a 3-factor solution in most of the samples that was robust across various demographic characteristics. Two factors appeared particularly robust: one reflected conscious use of cognitive coping strategies (with high loadings on ignoring pain and coping self-statements) and another reflected self-efficacy beliefs concerning pain (with high loadings on ability to control and decrease pain). A third factor, which was somewhat less stable, appeared to reflect avoidance of pain by attention to non-pain-related mental activity (with high loadings on diverting attention and praying and hoping). Scales reflecting catastrophizing cognitions and behavioral coping strategies did not consistently load on the above dimensions. Issues concerning the conceptualization and measurement of pain-related cognitive coping dimensions are discussed.

Adaptation, Psychological↗
PubMed1989

The matrix method of metabolic control analysis: its validity for complex pathway structures.

The sensitivities of the variables of a metabolic system (such as fluxes and concentrations) to variations in enzyme concentration are expressed in metabolic control analysis as control coefficients. The matrix method is a system of writing matrix equations that generate expressions for the control coefficients in terms of the characteristics of the components (principally the enzymes). Previously, the matrix method has been considered in terms of simple pathway structures; here we justify its applicability to complex pathways, such as those with multiple branches. It is shown that this requires modification of the branch point relationship to take account of changes of flux along the limbs of the branch and of stoichiometric factors. The method of deriving the flux control coefficients with respect to different fluxes in the system is extended to cope with these circumstances.

Animals↗
PubMed1995

Structure of the tetraheme cytochrome from Desulfovibrio desulfuricans ATCC 27774: X-ray diffraction and electron paramagnetic resonance studies.

The three-dimensional X-ray structure of cytochrome c3 from a sulfate reducing bacterium, Desulfovibrio desulfuricans ATCC 27774 (107 residues, 4 heme groups), has been determined by the method of molecular replacement [Frazão et al. (1994) Acta Crystallogr. D50, 233-236] and refined at 1.75 A to an R-factor of 17.8%. When compared with the homologous proteins isolated from Desulfovibrio gigas, Desulfovibrio vulgaris Hildenborough, Desulfovibrio vulgaris Miyazaki F, and Desulfomicrobium baculatus, the general outlines of the structure are essentialy kept [heme-heme distances, heme-heme angles, His-His (axial heme ligands) dihedral angles, and the geometry of the conserved aromatic residues]. The three-dimensional structure of D. desulfuricans ATCC 27774 cytochrome c3Dd was modeled on the basis of the crystal structures available and amino acid sequence comparisons within this homologous family of multiheme cytochromes [Palma et al. (1994) Biochemistry 33, 6394-6407]. This model is compared with the refined crystal structure now reported, in order to discuss the validity of structure prediction methods and critically evaluate the steps used to predict protein structures by homology modeling. The four heme midpoint redox potentials were determined by using deconvoluted electron paramagnetic resonance (EPR) redox titrations. Structural criteria (electrostatic potentials, heme ligand orientation, EPR g values, heme exposure, data from protein-protein interaction studies) are invoked to assign the redox potentials corresponding to each specific heme in the three-dimensional structure.

Crystallography, X-Ray↗