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Results for “Structural validation”

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PubMed1998

Predictive validity of cocaine, sedative, and alcohol dependence diagnoses.

This study examined the predictive validity of Structured Clinical Interview for DSM-III-R (Spitzer, Williams, Gibbon, & First, 1990) based substance dependence diagnoses (i.e., cocaine, sedative, and alcohol) for 518 opioid-dependent outpatients entering methadone maintenance. Patients were followed over 1 year of treatment, which involved daily methadone substitution supplemented by individual and group counseling. Urine specimens were tested randomly 1-4 times per month. Patients diagnosed with current cocaine, sedative, or alcohol dependence were more likely to use these drugs than were patients with past only or no dependence syndrome. Current cocaine dependence predicted early treatment dropout. The results demonstrate the predictive and discriminant validity of several substance dependence diagnoses common among patients in substance abuse or other psychiatric treatment settings.

Adult↗
PubMed2004

The impact of visit frequency on the relationship between service quality and outpatient satisfaction: a South Korean study.

OBJECTIVE: To examine the relative impact of four service quality dimensions on outpatient satisfaction and to test the invariance of the structural relationships between the service quality dimensions and satisfaction across three patient groups of varying numbers of prior visits to the same hospital as outpatients. DATA SOURCES/STUDY SETTING: Survey of 557 outpatients using a self-administered questionnaire over a 10-day period at a general hospital in Sungnam, South Korea. DATA COLLECTION: Patients answered questions related to two main constructs, patient satisfaction and health care service quality. The health care service quality measures (30 items) were developed based on the results of three focus group interviews and the SERVQUAL scale, while satisfaction (3 items) was measured using a previously validated scale. STUDY DESIGN: Confirmatory factor analysis was used to assess the construct validity of the service quality scale by testing convergent and divergent validity. A structural equation model specifying the four service quality dimensions as exogenous variables and patient satisfaction as an endogenous variable was estimated to assess the relative impact of each of the service quality dimensions on satisfaction. This was followed by a multigroup LISREL analysis that tested the invariance of structural coefficients across three groups with different frequencies of outpatient visits to the hospital. PRINCIPAL FINDINGS: Findings support the causal relationship between service quality and satisfaction in the context of the South Korean health care environment. The four service quality dimensions showed varying patterns of impact on patient satisfaction across the three different outpatient groups. CONCLUSION: The hospital management needs to be aware of the relative importance of each of the service quality dimensions in satisfaction formation of outpatients, which varies across different hospital utilization groups, and use this in strategic considerations.

Adult↗
PubMed2004

Measuring cognitive insight in middle-aged and older patients with psychotic disorders.

The study examined the psychometric properties, factor structure and validity of a recently developed measure of insight, the Beck Cognitive Insight Scale (BCIS) and tested the relationship between the BCIS and psychiatric symptoms in a sample of middle-aged and older patients with schizophrenia or schizoaffective disorder. The BCIS measures the ability of respondents to observe and question their cognitive processes, whereas other insight scales focus primarily on knowledge about the presence of an illness and need for treatment. Participants were 164 middle-aged and older outpatients with schizophrenia or schizoaffective disorder who completed a battery of measures assessing insight, symptoms of schizophrenia and symptoms of depression. The results of a confirmatory factor analysis (CFA) supported the two-factor structure previously reported for the BCIS, with one factor labeled self-reflectiveness and the other labeled self-certainty. The BCIS showed adequate reliability and a moderate correlation with the Birchwood Insight Scale (IS). The BCIS correlated with some PANSS subscales measuring symptoms of schizophrenia, but did not correlate at a significant level with symptoms of depression. The findings suggest that middle-aged and older outpatients with schizophrenia or schizoaffective disorder respond on the BCIS in a manner similar to a younger inpatient population. This instrument is a promising tool for measuring the role of cognitive change in a broad range of patients experiencing psychosis.

Adult↗
PubMed2002

Cross-validation by downweighting influential cases in structural equation modelling.

In the social and behavioural sciences, structural equation modelling has been widely used to test a substantive theory or causal relationship among latent constructs. Cross-validation (CV) is a valuable tool for selecting the best model among competing structural models. Influential cases or outliers are often present in practical data. Therefore, even the correct model for the majority of the data may not cross-validate well. This paper discusses various drawbacks of CV based on sample covariance matrices, and develops a procedure for using robust covariance matrices in the model calibration and validation stages. Examples illustrate that the CV index based on sample covariance matrices is very sensitive to influential cases, and even a single outlier can cause the CV index to support a wrong model. The CV index based on robust covariance matrices is much less sensitive to influential cases and thus leads to a more valid conclusion about the practical value of a model structure.

Behavioral Sciences↗
PubMed2002

Relationship between brain structure and saccadic eye movements in healthy humans.

This study used structural magnetic resonance imaging (MRI) to investigate associations between brain structure and saccadic eye movements. Seventeen healthy subjects underwent structural MRI and infra-red oculographic assessment of a reflexive saccade task. Volumes of prefrontal, premotor, and occipitoparietal cortex, caudate, thalamus, and cerebellar vermis were used as predictors in multiple regression with prosaccade gain as a dependent variable, controlling for whole-brain volume. Using voxel-based morphometry (VBM), gain was entered into correlational analysis with grey matter density. Regression analysis indicated that vermis volumes predicted prosaccade gain. VBM replicated this finding: gain was correlated with grey matter in the left cerebellar hemisphere and vermis. These findings agree with previous studies on the role of the cerebellar vermis in saccadic gain and support the validity of structural neuroimaging methods in elucidating the neural correlates of saccadic eye movements.

Adult↗
PubMed2001

SGP-1: prediction and validation of homologous genes based on sequence alignments.

Conventional methods of gene prediction rely on the recognition of DNA-sequence signals, the coding potential or the comparison of a genomic sequence with a cDNA, EST, or protein database. Reasons for limited accuracy in many circumstances are species-specific training and the incompleteness of reference databases. Lately, comparative genome analysis has attracted increasing attention. Several analysis tools that are based on human/mouse comparisons are already available. Here, we present a program for the prediction of protein-coding genes, termed SGP-1 (Syntenic Gene Prediction), which is based on the similarity of homologous genomic sequences. In contrast to most existing tools, the accuracy of depends little on species-specific properties such as codon usage or the nucleotide distribution. may therefore be applied to nonstandard model organisms in vertebrates as well as in plants, without the need for extensive parameter training. In addition to predicting genes in large-scale genomic sequences, the program may be useful to validate gene structure annotations from databases. To this end, SGP-1 output also contains comparisons between predicted and annotated gene structures in HTML format. The program can be accessed via a Web server at http://soft.ice.mpg.de/sgp-1. The source code, written in ANSI C, is available on request from the authors.

Algorithms↗
PubMed2005

Assessing personality with a structured employment interview: construct-related validity and susceptibility to response inflation.

The authors evaluated the extent to which a personality-based structured interview was susceptible to response inflation. Interview questions were developed to measure facets of agreeableness, conscientiousness, and emotional stability. Interviewers administered mock interviews to participants instructed to respond honestly or like a job applicant. Interviewees completed scales of the same 3 facets from the NEO Personality Inventory, under the same honest and applicant-like instructions. Interviewers also evaluated interviewee personality with the NEO. Multitrait-multimethod analysis and confirmatory factor analysis provided some evidence for the construct-related validity of the personality interviews. As for response inflation, analyses revealed that the scores from the applicant-like condition were significantly more elevated (relative to honest condition scores) for self-report personality ratings than for interviewer personality ratings. In addition, instructions to respond like an applicant appeared to have a detrimental effect on the structure of the self-report and interview ratings, but not interviewer NEO ratings.

Adult↗
PubMed1997

The AIMS2-SF: a short form of the Arthritis Impact Measurement Scales 2. French Quality of Life in Rheumatology Group.

OBJECTIVE: To develop a short form of the Arthritis Impact Measurement Scales 2 (AIMS2) questionnaire, preserving content validity as the priority criterion. METHODS: A 2-step reduction procedure was used: 1) Delphi technique, with 1 panel of patients and 1 panel of experts each selecting 1 set of items independently; and 2) nominal group technique, where members of both panels reached consensus on the final selection of items, using information derived from item analysis. Psychometric properties of the AIMS2-Short Form (AIMS2-SF) and AIMS2 were compared using data from a cohort of 127 rheumatoid arthritis patients who completed the AIMS2 twice prior to the initiation of methotrexate (MTX) treatment and 3 months post-initiation of MTX treatment. RESULTS: The 2 panels reached consensus on a 26-item AIMS2-SF (54.4% reduction from the AIMS2). Factor analysis showed preservation of the 5-component structure. Convergent validity (Physical and Symptom components with clinical variables: r = 0.24-0.59), test-retest reproducibility (intraclass correlation coefficient >0.7), and sensitivity to change at 3 months (standardized response mean 0.36-0.8, except Social Interaction component [0.08]) were very close to the values for the original AIMS2. CONCLUSION: The AIMS2-SF is a shorter version of the AIMS2 (i.e., available in 2-page format) and has psychometric properties similar to those of the AIMS2.

Activities of Daily Living↗
PubMed2001

Oxidative decarboxylation of UDP-glucuronic acid in extracts of polymyxin-resistant Escherichia coli. Origin of lipid a species modified with 4-amino-4-deoxy-L-arabinose.

Addition of the 4-amino-4-deoxy-l-arabinose (l-Ara4N) moiety to the phosphate groups of lipid A is implicated in bacterial resistance to polymyxin and cationic antimicrobial peptides of the innate immune system. The sequences of the products of the Salmonella typhimurium pmrE and pmrF loci, both of which are required for polymyxin resistance, recently led us to propose a pathway for l-Ara4N biosynthesis from UDP-glucuronic acid (Zhou, Z., Lin, S., Cotter, R. J., and Raetz, C. R. H. (1999) J. Biol. Chem. 274, 18503-18514). We now report that extracts of a polymyxin-resistant mutant of Escherichia coli catalyze the C-4" oxidation and C-6" decarboxylation of [alpha-(32)P]UDP-glucuronic acid, followed by transamination to generate [alpha-(32)P]UDP-l-Ara4N, when NAD and glutamate are added as co-substrates. In addition, the [alpha-(32)P]UDP-l-Ara4N is formylated when N-10-formyltetrahydrofolate is included. These activities are consistent with the proposed functions of two of the gene products (PmrI and PmrH) of the pmrF operon. PmrI (renamed ArnA) was overexpressed using a T7 construct, and shown by itself to catalyze the unprecedented oxidative decarboxylation of UDP-glucuronic acid to form uridine 5'-(beta-l-threo-pentapyranosyl-4"-ulose diphosphate). A 6-mg sample of the latter was purified, and its structure was validated by NMR studies as the hydrate of the 4" ketone. ArnA resembles UDP-galactose epimerase, dTDP-glucose-4,6-dehydratase, and UDP-xylose synthase in oxidizing the C-4" position of its substrate, but differs in that it releases the NADH product.

Amino Sugars↗
PubMed2001

Use of structural equation modeling to test the construct validity of a case definition of Gulf War syndrome: invariance over developmental and validation samples, service branches and publicity.

To attempt to replicate the syndrome-like structure identified by exploratory factor analysis of symptom reports from 249 Gulf War veterans of a Naval reserve battalion (the developmental sample), we administered Haley's original symptom questionnaire to 335 Gulf War veterans who served primarily in active-duty US Army units living in North Texas (the validation sample). On the basis of recently validated goodness-of-fit criteria (SRMR or=0.95), a structural equation model (Model 1) with four symptom scales loading on each of three first-order latent syndrome factors fit both the developmental and validation samples well and was invariant across both samples. Additional models validated a higher-order latent factor (a single Gulf War syndrome) explaining the variances and covariances of the first-order factors, four additional symptom scales loading on the higher-order factor, and four possible secondary factor loadings that also fit the data well. All structural models were invariant across cohorts of the validation sample surveyed before and after intense publicity following publication of the case definition. These findings suggest that the apparent syndrome structure of a single Gulf War syndrome with three variants may be found widely and justify a confirmatory sample survey of Gulf War-era veterans.

Adult↗
PubMedDate not supplied

Statistically based reduced representation of amino acid side chains.

Preferred conformations of amino acid side chains have been well established through statistically obtained rotamer libraries. Typically, these provide bond torsion angles allowing a side chain to be traced atom by atom. In cases where it is desirable to reduce the complexity of a protein representation or prediction, fixing all side-chain atoms may prove unwieldy. Therefore, we introduce a general parametrization to allow positions of representative atoms (in the present study, these are terminal atoms) to be predicted directly given backbone atom coordinates. Using a large, culled data set of amino acid residues from high-resolution protein crystal structures, anywhere from 1 to 7 preferred conformations were observed for each terminal atom of the non-glycine residues. Side-chain length from the backbone C(alpha) is one of the parameters determined for each conformation, which should itself be useful. Prediction of terminal atoms was then carried out for a second, nonredundant set of protein structures to validate the data set. Using four simple probabilistic approaches, the Monte Carlo style prediction of terminal atom locations given only backbone coordinates produced an average root mean-square deviation (RMSD) of approximately 3 A from the experimentally determined terminal atom positions. With prediction using conditional probabilities based on the side-chain chi(1) rotamer, this average RMSD was improved to 1.74 A. The observed terminal atom conformations therefore provide reasonable and potentially highly accurate representations of side-chain conformation, offering a viable alternative to existing all-atom rotamers for any case where reduction in protein model complexity, or in the amount of data to be handled, is desired. One application of this representation with strong potential is the prediction of charge density in proteins. This would likely be especially valuable on protein surfaces, where side chains are much less likely to be fixed in single rotamers. Prediction of ensembles of structures provides a method to determine the probability density of charge and atom location; such a prediction is demonstrated graphically.

Amino Acids↗
PubMed2002

Use of the Sport Orientation Questionnaire with wheelchair athletes: examination of evidence for validity.

The factor structure of the Sport Orientation Questionnaire with three factors of competitiveness, win orientation, and goal orientation was examined in a sample of 243 wheelchair athletes from the USA. Based on sample-specific validity evidence theory, it was hypothesized that the exploratory and confirmatory factor analyses would yield evidence on validity for wheelchair athletes who were different from able-bodied athletes. Exploratory factor analysis confirmed the hypothesis with a clear fourth and a questionable fifth factor. A confirmatory factor analysis did not adequately explain the new five-factor model. The new emerging fourth and fifth factors separated the competitiveness element of the questionnaire in 'self-referenced' and 'other-referenced' elements of competitiveness. Results are discussed in terms of demographic characteristics of the sample of wheelchair athletes.

Adult↗
PubMed2005

Structural brain correlates of prepulse inhibition of the acoustic startle response in healthy humans.

Neural regions modulating prepulse inhibition (PPI) of the startle response, an operational measure of sensorimotor gating, are well established from animal studies using surgical and pharmacological procedures. The limbic and cortico-pallido-striato-thalamic circuitry is thought to be responsible for modulation of PPI in the rat. The involvement of this circuitry in human PPI is suggested by observations of deficient PPI in a number of neuropsychiatric disorders characterized by abnormalities at some level in this circuitry and recent functional neuroimaging studies in humans. The current study sought to investigate structural neural correlates of PPI in a sample of twenty-four right-handed, healthy subjects (10 men, 14 women). Subjects underwent magnetic resonance imaging (MRI) at 1.5 T and were assessed (off-line) on acoustic PPI using electromyographic recordings of the orbicularis oculi muscle beneath the right eye. Optimized volumetric voxel-based morphometry (VBM) implemented in SPM99 was used to investigate the relationship of PPI (prepulse onset-to-pulse onset interval 120 ms) to regional grey matter volumes, covarying for sex. Significant positive correlations were obtained between PPI and grey matter volume in the hippocampus extending to parahippocampal gyrus, basal ganglia including parts of putamen, globus pallidus, and nucleus accumbens, superior temporal gyrus, thalamus, and inferior frontal gyrus. These findings identify the relationship between PPI and grey matter availability on a highly spatially localized scale in brain regions shown to be activated in recent functional neuroimaging studies in association with PPI in healthy humans and demonstrate the validity of structural neuroimaging methods in delineating the neural mechanisms underlying human PPI.

Acoustic Stimulation↗
PubMed2006

Co-evolutionary analysis of domains in interacting proteins reveals insights into domain-domain interactions mediating protein-protein interactions.

Recent advances in functional genomics have helped generate large-scale high-throughput protein interaction data. Such networks, though extremely valuable towards molecular level understanding of cells, do not provide any direct information about the regions (domains) in the proteins that mediate the interaction. Here, we performed co-evolutionary analysis of domains in interacting proteins in order to understand the degree of co-evolution of interacting and non-interacting domains. Using a combination of sequence and structural analysis, we analyzed protein-protein interactions in F1-ATPase, Sec23p/Sec24p, DNA-directed RNA polymerase and nuclear pore complexes, and found that interacting domain pair(s) for a given interaction exhibits higher level of co-evolution than the non-interacting domain pairs. Motivated by this finding, we developed a computational method to test the generality of the observed trend, and to predict large-scale domain-domain interactions. Given a protein-protein interaction, the proposed method predicts the domain pair(s) that is most likely to mediate the protein interaction. We applied this method on the yeast interactome to predict domain-domain interactions, and used known domain-domain interactions found in PDB crystal structures to validate our predictions. Our results show that the prediction accuracy of the proposed method is statistically significant. Comparison of our prediction results with those from two other methods reveals that only a fraction of predictions are shared by all the three methods, indicating that the proposed method can detect known interactions missed by other methods. We believe that the proposed method can be used with other methods to help identify previously unrecognized domain-domain interactions on a genome scale, and could potentially help reduce the search space for identifying interaction sites.

Amino Acid Sequence↗
PubMed1998

Iditis: protein structure database.

The validation, enrichment and organization of the data stored in PDB files is essential for those data to be used accurately and efficiently for modelling, experimental design and the determination of molecular interactions. The Iditis protein structure database has been designed to allow the widest possible range of queries to be performed across all available protein structures. The Iditis database is the most comprehensive protein structure resource currently available, and contains over 500 fields of information describing all publicly deposited protein structures. A custom-written database engine and graphical user interface provide a natural and simple environment for the construction of searches for complex sequence- and structure-based motifs. Extensions and specialized interfaces allow the data generated by the database to used in conjunction with a wide range of applications.

Database Management Systems↗
PubMed1985

Epidemiology: reflections on testing the validity of psychiatric interviews.

Laboratory tests that validate psychiatric disorder are unavailable. Accordingly, the validity of structured diagnostic interviews such as the Diagnostic Interview Schedule have been assessed through a double-blind test-retest design. This approach compares the Diagnostic Interview Schedule to a clinician's assessment and evaluates its results by three statistics: sensitivity and specificity, for which the clinician's interview serves as the standard, and K, which measures concordance between the two interviews. This design is found wanting on several counts: the reinterview may be answered differently because of clinical change or because of its meaning to the respondent; the clinician's interview may be an erratic standard; and the statistics are affected by both prevalence and severity of disorder. Furthermore, the statistics may not predict the accuracy of prevalence estimates made by the interview or its ability to detect correlates of disorder. Some alternative approaches are suggested.

Clinical Trials as Topic↗
PubMed1978

Wechsler Memory Scale: a selective review of the literature.

Research on the Wechsler Memory Scale (WMS) is reviewed with respect to questions of its reliability, factor structure, construct validity, and utility. The relationship of Memory Quotient to Full Scale IQ is explored and the conditions under which disparity between the two scores may be clinically useful indicated. Despite its numerous limitations, the WMS has been a sensitive test of short-term verbal memory. As such, it may be helpful in identifying impairment of the dominant (left) temporal lobe and its medial hippocampal connections. The test is badly in need of re-standardization, however, and suggestions for improving the instrument are made.

Adult↗