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PubMed2006

Do MRI findings correlate with mobility tests? An explorative analysis of the test validity with regard to structure.

To find out whether segmental magnetic resonance imaging (MRI) findings such as intervertebral disc degeneration (DD) and facet joint osteoarthritis (FJO) are associated with motion deficiencies as seen in common mobility tests and observed range of motion (ROM). A total of 112 female subjects, nurses and office workers, with and without low back pain, were examined by clinical experts, and lumbar mobility was measured including modified Schober, fingertip-to-floor distance (FTFD) and ZEBRIS motion analysis. An MRI of the lumbar spine was made. Mobility findings were correlated with segmental morphologic changes as seen on MRI at the levels of L1-2 through L5-S1. Only a few statistically significant correlations between MRI findings and the results of the mobility tests could be found. Lateral bending was weakly and negatively correlated to DD and FJO but only on the level of L5-S1. The FTFD showed a weak positive correlation to endplate changes on the level of L4-5. When ROM is observed by clinical experts, there are several significant relationships between MRI findings and the observed motion. There is a highly significant segmental correlation between DD and disc form alteration as seen on MRI on the level of single motion segments. Pain history and current pain level did not moderate any association between MRI and mobility. There is no clear relationship between the structural changes represented by MRI and the measured mobility tests used in this study. Our findings suggest that close observation of spinal motion may provide at least equal information about the influence of spinal structures on motion than the commonly used measured mobility tests do.

Adult↗
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↗
PubMed2005

Combining in silico tools and NMR data to validate protein-ligand structural models: application to matrix metalloproteinases.

A combination of in silico tools and experimental NMR data is proposed for relatively fast determination of protein-ligand structural models and demonstrated from known inhibitors of matrix metalloproteinases (MMP). The 15N 1H heteronuclear single quantum coherence (HSQC) spectral assignment and the 3D structure, either X-ray or NMR, are needed. In this method, the HSQC spectrum with or without the ligand is used to determine the interaction region of the ligand. Docking calculations are then performed to obtain a set of structural models. From the latter, the nuclear Overhauser effects (NOEs) between the ligand and the protein can be predicted. Guided by these predictions, a number of NOEs can be detected and assigned through a HSQC NOESY experiment. These data are used as structural restraints to reject/refine the initial structural models through further in silico work. For a test protein (MMP-12, human macrophage metalloelastase), a final structure of a protein-ligand adduct was obtained that matches well with the full structural determination. A number of structural predictions were then made for adducts of a similar protein (MMP-1, human fibroblast collagenase) with the same and different ligands. The quality of the final results depended on the type and number of experimental NOEs, but in all cases, a well-defined ligand conformation in the protein binding site was obtained. This protocol is proposed as a viable alternative to the many approaches described in the literature.

Alanine↗
PubMed2002

Structure-based design of mutant Methanococcus jannaschii tyrosyl-tRNA synthetase for incorporation of O-methyl-L-tyrosine.

Although incorporation of amino acid analogs provides a powerful means of producing new protein structures with interesting functions, many amino acid analogs cannot be incorporated easily by using the wild-type aminoacyl-tRNA synthetase (aaRS). To be able to incorporate specific amino acid analogs site-specifically, it is useful to build a mutant aaRS that preferentially activates the analog compared with the natural amino acids. Experimental combinatorial studies to find such mutant aaRSs have been successful but can easily become costly and time-consuming. In this article, we describe the clash opportunity progressive (COP) computational method for designing a mutant aaRS to preferentially take up the analog compared with the natural amino acids. To illustrate this COP procedure, we apply it to the design of mutant Methanococcus jannaschii tyrosyl-tRNA synthetase (M.jann-TyrRS). Because the three-dimensional structure for M.jann-TyrRS was not available, we used the STRUCTFAST homology modeling procedure plus molecular dynamics with continuum solvent forces to predict the structure of wild-type M.jann-TyrRS. We validate this structure by predicting the binding site for tyrosine and calculating the binding energies of the 20 natural amino acids, which shows that tyrosine binds the strongest. With the COP design algorithm we then designed a mutant tyrosyl tRNA synthetase to activate O-methyl-l-tyrosine preferentially compared with l-tyrosine. This mutant [Y32Q, D158A] is similar to the mutant designed with combinatorial experiments, [Y32Q, D158A, E107T, L162P], by Wang et al. [Wang, L., Brock, A., Herberich, B. & Schultz, P. G. (2001) Science 292, 498-500]. We predict that the new one will have much greater activity while retaining significant discrimination between O-methyl-l-tyrosine and tyrosine.

Amino Acids↗
PubMed2000

A Swedish translation of the 20-item Toronto Alexithymia Scale: cross-validation of the factor structure.

The purpose of this study was to develop a new Swedish translation of the twenty-item Toronto Alexithymia Scale (TAS-20) and to examine if the theoretical structure that underlies the factor structure of the English version of the TAS-20 could be recovered in this Swedish translation of the instrument. A sample of 157 undergraduate students of psychology was tested. Using confirmatory factor analysis, the previously established three-factor TAS-20 model was found to be replicable in this sample. In addition, the Swedish translation of the TAS-20 showed adequate internal reliability. The present study also illustrates the importance of using back translation methodology when transposing psychometric instruments from one language to another.

Adult↗
PubMed2005

Screening ADHD problems in the sports behavior checklist: factor structure, convergent and divergent validity, and group differences.

The Sports Behavior Checklist (SBC) is subjected to a principal components analysis, and subscales are correlated with subscales of the Conners' Revised Parent Form and the Social Skills Rating System. Both of these analyses are conducted to determine the construct validity of the instrument. A subsample of lower socioeconomic status individuals is used to compare ADHD and control group differences on the subscales of the SBC. The authors find that a six-factor solution, as proposed by the original authors, accounted for 71.5% of the variance. As hypothesized, subscales on the SBC are low to moderately related to subscales on the anchor measures. Significant group differences are found on the Aggression, Emotional Reactivity, and Injury subscales. Implications and limitations are discussed.

Attention Deficit Disorder with Hyperactivity↗
PubMed2001

Suppression of valid inferences and knowledge structures: the curious effect of producing alternative antecedents on reasoning with causal conditionals.

These studies looked at the difficulty that reasoners have in accepting conditional ("If P then Q") major premises that are not necessarily true empirically, as a basis for deductive reasoning. Preliminary results have shown that when reasoners are asked to produce possible alternate antecedents to the major premise ("If A then Q"), they paradoxically tend to deny the modus ponens (MP) inference ("If P is true, then Q is true"). Three studies further explored these results. The first study gave university students paper-and-pencil tests in which instructions to "suppose that the major premise is true" was followed by a request to determine the next number in a sequence, to retrieve information unrelated to the premises, or to retrieve a possible case of "If A then Q." Relative to a control group, reasoners asked to produce an alternative antecedent showed a significant tendency to deny the MP inference, whereas no such tendency was observed for the two other tasks used. A second study compared performance on a condition in which reasoners were asked to produce an alternative antecedent with that when they were given an explicit alternative. Premises used in this study were such that the latter alternative antecedent was also spontaneously produced by over 70% of reasoners. Results showed that the tendency to refuse the MP premise could not be accounted for by the specific nature of the alternative produced. A third study found that the tendency to refuse the MP inference after producing an alternative antecedent was affected by the number of "disabling conditions" (i.e., conditions that allow "P to be true" and "Q to be false") available for the major premise. These results are interpreted as being consistent with a model that supposes that logical reasoning requires selective inhibition of real-world knowledge.

Adult↗
PubMedDate not supplied

A POMS short form for cancer patients: psychometric and structural evaluation.

The internal consistency, validity, and factor structure of the Shacham shortened version (37 items) of the 65-item profile of mood states (POMS) were examined with a sample of 428 cancer patients who were awaiting bone marrow transplantation. Cronbach's alphas ranging from 0.78 to 0.91 were obtained for each of the six subscales of the POMS-short form (POMS-SF) and for the total 37-item scale. Correlations with the CES-D, the Self-Rated Karnofsky, the MOS SF-20 Physical Functioning, and the Bradburn Positive and Negative Affect Scales provided evidence of the convergent and discriminant validity of the POMS-SF. Results of a confirmatory factor analysis were supportive of the 6-factor interpretation of the POMS items in the 37-item version of the POMS.

Adaptation, Psychological↗
PubMed1996

[Validity of videolaryngoscopy in detecting laryngeal structural changes].

STUDY OBJECTIVE: To determinate the validity of videolaryngoscopy on diagnose of laryngeal diseases versus other laryngoscopic methods. DESIGN: Retrospective study covering 2 years (1992 and 1993). SETTING: 267 were the consulting patients because of dysphony. This collective was ranged in 2 groups. Group A included those hoarse individuals in whom was detected a growth, confirmed afterwards by means of direct laryngoscopy, biopsy and pathologists examination of a smear. Group B was formed for dysphonics with no organic changes seen through indirect laryngoscopy. INTERVENTIONS: All patients underwent indirect laryngoscopy (laryngeal mirror) and videolaryngoscopy. Patients showing an organic lesion underwent, also, suspension direct laryngoscopy, biopsy and histopathological control (reference's measurement). In all laryngoscopic procedures were determinated presence or absence of laryngeal changes (organic or functional) and the glottic area involved. RESULTS: In 156 patients direct laryngoscopies were performed. Organic lesion could be confirmed in 154 cases. The relative sensibility of videolaryngoscopy versus laryngeal mirror account for 0.4 and its negative predictive value for 0.26. The correlation videolaryngoscopy direct laryngoscopy results in 1. CONCLUSIONS: Videolaryngoscopy is a method with major sensibility and negative predictive value as indirect laryngoscopy with mirror. But the latter is indispensable in diagnosis of laryngeal organic lesions and must be done prior to microlaryngoscopie direct examination.

Humans↗
PubMed2000

The CATH Dictionary of Homologous Superfamilies (DHS): a consensus approach for identifying distant structural homologues.

A consensus approach has been developed for identifying distant structural homologues. This is based on the CATH Dictionary of Homologous Superfamilies (DHS), a database of validated multiple structural alignments annotated with consensus functional information for evolutionary protein superfamilies (URL: http://www. biochem.ucl.ac.uk/bsm/dhs). Multiple structural alignments have been generated for 362 well-populated superfamilies in the CATH structural domain database and annotated with secondary structure, physicochemical properties, functional sequence patterns and protein-ligand interaction data. Consensus functional information for each superfamily includes descriptions and keywords extracted from SWISS-PROT and the ENZYME database. The Dictionary provides a powerful resource to validate, examine and visualize key structural and functional features of each homologous superfamily. The value of the DHS, for assessing functional variability and identifying distant evolutionary relationships, is illustrated using the pyridoxal-5'-phosphate (PLP) binding aspartate aminotransferase superfamily. The DHS also provides a tool for examining sequence-structure relationships for proteins within each fold group.

Amino Acid Sequence↗
PubMedDate not supplied

[Clinical assessment of schizophrenic syndrome (CASS): validity evaluation of the new diagnostic tool].

AIM: The aim of the study was an evaluation of validity measures of the CASS (Clinical Assessment of Schizophrenic Syndromes)--a new multi-purpose and multi-level clinical diagnostic instrument consisting of a diagnostic questionnaire (CASS-D) allowing to analyze a diagnosis of schizophrenia according to DSM-IV and ICD-10 criteria as well as of three rating scales designed for description and intensity evaluation of schizophrenic syndromes on the global (CASS-G), dimensional (CASS-P, a profile of 13 basic dimensions) or symptomatological (CASS-S, a set of 31 symptoms) level. SUBJECTS: 194 inpatients consecutively admitted to the Department within approximately 6 months were assessed twice (at the start and end of their hospitalization) by 12 trained diagnosticians. METHOD: Several measures of validity were analyzed. Results obtained by means of CASS were compared with results of the SANS/SAPS, BPRS, and PANSS as reference rating scales (diagnostic validity). Characteristics of frequency, intensity, dynamics and specificity of scale items were used to analyze content validity. Factorial structure of CASS scales was applied as a measure of construct validity. FINDINGS: Diagnostic validity of the new instrument seems to be confirmed by its very high correlation coefficients with rating scales recognized as international standards: BPRS, PANSS, and SANS/SAPS. Reasonable characteristics of frequency, intensity, dynamics and specificity of individual items (dimensions, symptoms) and sum scores of CASS scales and relationships between their values strongly suggest their content validity. Both sum (CASS-P, CASS-S) and global (CASS-G) scores of scales under study revealed some specificity--they had significantly higher values in patients with schizophrenia than in patients with other diagnoses. It allows to distinguish in a schizophrenic syndrome described by CASS components which are specific and not specific for this disorder. The latter have been left also in the final version for their practical and clinical importance. Construct validity of the CASS was studied separately for different scales (CASS-P, CASS-S) and different groups (all or only schizophrenic patients) by means of several factor analyses, and performed along identical statistical procedure (principal component method of extraction with criterion eigenvalue > 1, followed by Equamax rotation). Resulting solutions could be interpreted reasonably and consistently with contemporary attempts to find adequate factorial models of intrinsic structure of schizophrenic syndrome. Thus they support confidence for constructive aspect of the CASS validity. CONCLUSIONS: Ultimately, results obtained in the study suggest that the CASS may be considered as an instrument with some promising indices of diagnostic, content and construct validity, which may be potentially useful for clinical and research purposes.

Humans↗
PubMed2005

A structured communication adolescent guide (SCAG): assessment of reliability and validity.

PURPOSE: To assess the reliability and validity of a Structured Communication Adolescent Guide (SCAG) in an undergraduate medical education setting using trained adolescent raters. METHOD: The SCAG is a 49-item, 6-section (A-F), protocol derived from the Calgary Cambridge Observation Guide that incorporates adolescent psychosocial data collection with the physician's communication skills. Four trained female adolescents scored 42 videotaped adolescent clinical encounters using the SCAG; a trained psychologist's rating for each videotape was used as the gold standard. RESULTS: Agreement among adolescent raters was determined by calculating intraclass correlation coefficients (ICC). The individual SCAG item scores, combined with the global ratings for each section, resulted in an overall ICC value of 0.93, indicating very strong agreement among the 4 raters. The global rating scores for the sections ('initiating the session', 'initiating separation', 'once adolescent is alone--lifestyle' and 'closure') produced an ICC range of 0.58-0.93. However, the ICC values for the 2 remaining sections ('how was information collected' and 'gathering information') global rating scores were below 0.30, signifying low agreement. Overall agreement between the adolescent raters and the gold standard resulted in an ICC value of 0.78. This is evidence of the SCAG's criterion validity. CONCLUSION: The SCAG is a reasonably valid tool for use in guiding an encounter with an adolescent patient. However, 2 sections require modifications to improve their reliability and thus the SCAG's overall performance. Our results suggest that the SCAG shows promise as a potentially useful teaching resource in undergraduate medical education in adolescent medical interviewing.

Adolescent↗