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At least 1,657 records · Page 92Linked to original sources
PubMed2005

[Development of internet addiction measurement scales and Korean internet addiction index].

OBJECTIVES: To develop measurement scales of Internet addiction, and propose a Korean Internet Addiction Index (K-IAI) and classification criteria for Internet addiction from the threshold scores developed. METHODS: The identification of the concept of "Internet addiction" was based on the literature review. To select the scales, an exploratory factor analysis was applied. A construct validation was tested by a confirmatory factor analysis (CFA) with a structured equation model (SEM). In testing the validity of the classification criteria, ANOVA and non-recursive models with SEM were applied. RESULTS: Out of 1,080 questionnaires distributed, 1,037 were returned,; a response rate of 96%. The Cronbach-alpha of all items was over 0.75. Using an exploratory factor analysis in the condition of a 6 factor constrain as the study model proposed, 23 of the initial 28 items were identified. In testing the discriminant and convergent validity of the selected 23 scales using CFA with SEM, the Internet addiction model explained about 93% of all variances of the data collected, and all the latent variables significantly explained the designated scales. A K-IAI was proposed using the T-scores of the sum of all factor averages. In the classification of users, the basic concept was a two-standard deviation approach of the K-IAI as the criteria of MMPI. The addiction group had a score > or =70 in the K-IAI, the pre-addiction group between > or =50 and <70, and the average user group <50. The Internet use times of the classified groups were statistically different in the ANOVA and multiple comparisons. CONCLUSIONS: The K-IAI is a reliable and valid instrument for measuring Internet addiction. Moreover, the taxonomy of the groups was also verified using various methods.

Behavior, Addictive↗
PubMed2005

Validity of an instrument assessing oral health problems in people with Down syndrome.

AIM: The aim of this study was to validate a proxy measure of oral health designed to be completed by the English-speaking parents of people with Down syndrome (DS) aged four years or more. METHODOLOGY: Items were generated through literature review, interviews with parents of people with DS and professional experts and through frequency testing. Data were gathered from one population-based and two clinic-based samples for the separate aspects of validation. Validation consisted of evaluation of: i) internal reliability of the domain structure through Cronbach's alpha; ii) criterion validity against clinical indicators and a clinician's evaluation of some items; iii) construct validity involving an age-matched comparison of domain scores between people with DS and non-DS siblings, and within the DS group by health status indicators; and iv) test-retest reliability through the generation of intra-class correlation coefficients (ICC). RESULTS: A 20-item instrument with four domains (communication, eating, parafunction and symptoms) was developed. Cronbach's alpha by domain was 0.5-0.8. Indicators of criterion validity for domains against clinical indicators (Spearman's coefficient 0.1-0.4) and parent-rated items against clinician-rated items (weighted Kappa 0.1-0.8) were varied as anticipated. Indicators of construct validity (differences with non-DS siblings and correlations with medical status within the DS group) were excellent. Test-retest reliability was good (ICC range 0.64-0.84). CONCLUSION: These data suggest the test instrument is valid as a descriptive, discriminative, proxy English language measure of oral health problems in people with DS aged four years or more.

Adolescent↗
PubMed1996

Comprehensive comparison of structural characteristics in eukaryotic cytoplasmic large subunit (23 S-like) ribosomal RNA.

Comparative modeling of secondary structure is a proven approach to predicting higher order structural elements in homologous RNA molecules. Here we present the results of a comprehensive comparison of newly modeled or refined secondary structures for the cytoplasmic large subunit (23 S-like) rRNA of eukaryotes. This analysis, which covers a broad phylogenetic spectrum within the eukaryotic lineage, has defined regions that differ widely in their degree of structural conservation, ranging from a core of primary sequence and secondary structure that is virtually invariant, to highly variable regions. New comparative information allows us to propose structures for many of the variable regions that had not been modeled before, and rigorously to confirm or refine variable region structures previously proposed by us or others. The present analysis also serves to identify phylogenetically informative features of primary and secondary structure that characterize these models of eukaryotic cytoplasmic 23 S-like rRNA. Finally, the work summarized here provides a basis for experimental studies designed both to test further the validity of the proposed secondary structures and to explore structure-function relationships.

Base Sequence↗
PubMed2002

Cross-cultural validity of the physical self-description questionnaire: comparison of factor structures in Australia, Spain, and Turkey.

We evaluated the cross-cultural generalizability of the factor structure for the Physical Self-Description Questionnaire (PSDQ) using confirmatory factor analysis. The factor structure was reasonably invariant over large samples of responses by Australian, Spanish, and Turkish students. Consistent with a priori predictions, the factor structures based on Australian and Spanish high school students were somewhat more similar to each other than to those based on Turkish university students, but these differences were small. Psychometric, theoretical cross-cultural, and practical considerations support the PSDQ's usefulness in a variety of research and applied settings. The study also provides a model for comparing psychometric properties based on responses to original and translated versions of sport psychology measures.

Adolescent↗
PubMed2006

Bhageerath: an energy based web enabled computer software suite for limiting the search space of tertiary structures of small globular proteins.

We describe here an energy based computer software suite for narrowing down the search space of tertiary structures of small globular proteins. The protocol comprises eight different computational modules that form an automated pipeline. It combines physics based potentials with biophysical filters to arrive at 10 plausible candidate structures starting from sequence and secondary structure information. The methodology has been validated here on 50 small globular proteins consisting of 2-3 helices and strands with known tertiary structures. For each of these proteins, a structure within 3-6 A RMSD (root mean square deviation) of the native has been obtained in the 10 lowest energy structures. The protocol has been web enabled and is accessible at http://www.scfbio-iitd.res.in/bhageerath.

Computational Biology↗
PubMed1998

Factorial structure of the Positive and Negative Syndrome Scale (PANSS): a forced five-dimensional factor analysis.

We conducted a study on 205 schizophrenic patients in order to explore the factorial structure of the Positive and Negative Syndrome Scale (PANSS). We first documented the validity and reliability of the five-dimensional structure of the PANSS, initially derived from the work of Kay and Sevy and completed by Lindenmayer et al. Some items (stereotyped thinking, mannerisms and posturing, poor attention, lack of judgement, disturbance of volition, and preoccupation) appeared to contribute little to the constitution of the dimensions initially described by Kay and Sevy. Those items were not taken into account in the forced five-dimensional factor analysis. We therefore investigated further the psychometric properties of the PANSS using only the retained items. The validity and reliability of this new five-dimensional structure are discussed.

Adolescent↗
PubMed1995

Intervertebral variation in trabecular microarchitecture throughout the normal spine in relation to age.

The vertebral bodies of the complete spine (C-3-L-5) were removed in 26 autopsy cases without evidence for primary or secondary bone disease (13 males aged 19-79 years and 13 females aged 17-90 years). A sagittal segment through the center of all vertebral bodies was embedded undecalcified in hydroxyethylmethacrylate and processed to so-called surface stained block grindings. Histomorphometric analysis of the complete segment was performed using a computer-assisted image analysis system (IBAS 2000). The structural parameters investigated were bone volume (BV/TV) and trabecular interconnection quantificated by trabecular bone pattern factor (TBPf). A close correlation of BV/TV and TBPf was found in all vertebral bodies irrespective of vertebral region (r = 0.8, p < 0.001). This indicates that the age-related decrease of trabecular bone mass is primarily the consequence of the transformation from plates to rods and the loss of whole trabecular structures. This basic principle is valid throughout the complete spine. However, the systematic analysis of vertebral trabecular bone from C-3 to L-5 revealed a significant intervertebral variation of trabecular microarchitecture. The density of trabecular structure of cervical vertebrae is much higher than that of thoracic and lumbar vertebrae (p < 0.001). The extent of age-related loss of trabecular bone mass and structure showed a decrease within the spine from the caudal to the cranial region (p < 0.05). The loss of bone volume in individuals between the ages of 30 and 80 years in the lumbar spine was 53%, whereas in the thoracic spine the decrease was 41%, and in the cervical spine only 24%.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMedDate not supplied

(13)C NMR quantitative spectrometric data-activity relationship (QSDAR) models of steroids binding the aromatase enzyme.

Five quantitative spectroscopic data-activity relationships (QSDAR) models for 50 steroidal inhibitors binding to aromatase enzyme have been developed based on simulated (13)C nuclear magnetic resonance (NMR) data. Three of the models were based on comparative spectral analysis (CoSA), and the two other models were based on comparative structurally assigned spectral analysis (CoSASA). A CoSA QSDAR model based on five principal components had an explained variance (r(2)) of 0.78 and a leave-one-out (LOO) cross-validated variance (q(2)) of 0.71. A CoSASA model that used the assigned (13)C NMR chemical shifts from a steroidal backbone at five selected positions gave an r(2) of 0.75 and a q(2) of 0.66. The (13)C NMR chemical shifts from atoms in the steroid template position 9, 6, 3, and 7 each had correlations greater than 0.6 with the relative binding activity to the aromatase enzyme. All five QSDAR models had explained and cross-validated variances that were better than the explained and cross-validated variances from a five structural parameter quantitative structure-activity relationship (QSAR) model of the same compounds. QSAR modeling suffers from errors introduced by the assumptions and approximations used in partial charges, dielectric constants, and the molecular alignment process of one structural conformation. One postulated reason that the variances of QSDAR models are better than the QSAR models is that (13)C NMR spectral data, based on quantum mechanical principles, are more reflective of binding than the QSAR model's calculated electrostatic potentials and molecular alignment process. The QSDAR models provide a rapid, simple way to model the steroid inhibitor activity in relation to the aromatase enzyme.

Aromatase↗
PubMedDate not supplied

Automatic annotation of BIND molecular interactions from three-dimensional structures.

Software to automate the process of extracting molecular interactions from three-dimensional (3D) structures has been developed that records these as Biomolecular Interaction Network Database (BIND) pairwise interaction records. Full annotation of BIND records is provided through a database processing tool called MMDBind, including detailed atom-atom and residue-residue level interaction information. BIND three-dimensional interaction annotation is synthesized by combining information from the Molecular Modeling Database (MMDB), and the HET (heterogen) group dictionary of small molecules in the macromolecular Crystallographic Information Format (mmCIF). Interactions are validated using the Protein Quaternary Structure (PQS) system. A total of 18,166 interactions were removed as being redundant or biologically irrelevant after PQS validation. This first pass MMDBind annotation creates two new divisions of BIND, 3D Biopolymers (BIND-3DBP) comprising 16,737 initial interaction records, and 3D Small Molecules (BIND-3DSM) comprising 48,219 records. Visualization of interacting residues and nucleotides within a macromolecular structure is possible directly from the BIND database owing to added 3D feature annotation within the BIND records that can be conveniently seen using Cn3D ("see-in-3D") after query from the BIND Data Manager. These interaction records provide a further demonstration of the completeness of the BIND data specification and its capabilities as storage and exchange format for all kinds of molecular interactions, including RNA, DNA, protein, and small molecules. Data from the 3DBP and 3DSM sets are available for downloading in Abstract Syntax Notation.1 (ASN.1) or Extensible Markup Language (XML) formats at ftp://ftp.bind.ca/DB/MMDBBind. Data from the 3DBP set is available for interactive query from the BIND Data Manager at www.bind.ca.

Crystallography, X-Ray↗
PubMed2005

Short form of Sarason's Social Support Questionnaire: French adaptation and validation.

The original short form of Sarason's Social Support Questionnaire measures two dimensions of social support, availability and satisfaction. The factorial structure of the social support was assessed in a French sample along with the association between the dimensions of social support and personality traits such as Extraversion, Neuroticism, and Depression. A 6-item French version was administered to 648 subjects: 348 university freshmen (228 females, 120 males) and 304 unemployed men. A principal component analysis followed by oblique rotations was undertaken on each sample. This yielded two factors, Availability and Satisfaction. These results sustained the stability of the factorial structure from one culture to another. Validity and reliability were satisfactory. Moreover, these two dimensions were correlated with two personality scales (high extraversion, low depression). Such results agree with previous results establishing relations between social support and salutogenic dimensions of personality.

Adolescent↗
PubMed2004

Making sense of olfaction through predictions of the 3-D structure and function of olfactory receptors.

We used the MembStruk first principles computational technique to predict the three-dimensional (3-D) structure of six mouse olfactory receptors (S6, S18, S19, S25, S46 and S50) for which experimental odorant recognition profiles are available for a set of 24 odorants (4-9 carbons aliphatic alcohols, acids, bromo-acids and diacids). We used the HierDock method to scan each predicted OR structure for potential odorant binding site(s) and to calculate binding energies of each odorant in these binding sites. The calculated binding affinity profiles are in good agreement with experimental activation profiles, validating the predicted 3-D structures and the predicted binding sites. For each of the six ORs, the binding site is located between trans-membrane domains (TMs) 3-6, with contributions from extracellular loops 2 and 3. In particular, we find six residue positions in TM3 and TM6 to be consistently involved in the binding modes of the odorants. Indeed, the differences in the experimental recognition profiles can be explained on the basis of these critical residues alone. These predictions are also consistent with mutation data on ligand binding for catecholamine receptors and sequence hypervariability studies for ORs. Based on this analysis, we defined amino acid patterns associated with the recognition of short aliphatic alcohols and mono-acids. Using these two sequence fingerprints to probe the alignment of 869 OR sequences from the mouse genome, we identified 34 OR sequences matching the fingerprint for aliphatic mono-acids and 36 corresponding to the recognition pattern for aliphatic alcohols. We suggest that these two sets of ORs might function as basic arrays for uniquely recognizing aliphatic alcohols and acids. We screened a library of 89 additional molecules against the six ORs and found that this set of ORs is likely to respond to aldehydes and esters with longer carbon chains than their currently known agonists. We also find that compounds associated with the flavor in foods are often among the best calculated binding affinities. This suggests that physiologic ligands for these ORs may be found among aldehydes and esters associated with flavor.

Acids↗
PubMed2002

Factors affecting gas-phase deuterium scrambling in peptide ions and their implications for protein structure determination.

In this report, we evaluate the validity of using hydrogen/deuterium exchange in combination with collision-induced dissociation mass spectrometry (CID MS) for the detailed structural and conformational investigation of peptides and proteins. This methodology, in which partly deuterated peptide ions are subjected to collision-induced dissociation in the vacuum of a mass spectrometer, has emerged as a useful tool in structural biology. It may potentially provide quantitatively the extent of deuterium incorporation per individual amino acid in peptides and proteins, thus providing detailed structural information related to protein structure and folding. We report that this general methodology has limitations caused by the fact that the incorporated deuterium atoms migrate prior or during the CID MS analysis. Our data are focused on a variety of transmembrane peptides, incorporated in a lipid bilayer, in which the near-terminal amino acids that anchor at the lipid-water interface are systematically varied. Our findings suggest that, under the experimental conditions we use, the extent of intramolecular hydrogen scrambling is strongly influenced by experimental factors, such as the exact amino acid sequence of the peptide, the nature of the charge carrier, and therefore most likely by the gas-phase structure of the peptide ion. Moreover, the observed scrambling seems to be independent of the nature of the peptide fragment ions (i.e., protonated B and Y' ' ions, and sodiated A and Y' ions). Our results strongly suggest that scrambling may be reduced by using alkali metal cationization instead of protonation in the ionization process.

Amino Acid Sequence↗
PubMed1977

Lipophilicity and brain disposition of clonidine and structurally related imidazolidines.

The apparent partition coefficients (P') of clonidine and 27 of its structurally related imidazolidines were determined in the octanol/buffer (pH = 7.4) system as a measure of lipophilic behaviour. Lipophilicity of the imidazolidines is limited to the free bases and the principle of additivity is valid for this series of structurally similar compounds. Brain concentrations of clonidine and a number of its derivatives, achieved at the moment of maximal decrease in blood pressure, were determined following intravenous administration of anaesthetized rats. These brain concentrations represent the maximally attainable values. The ratio of log brain concentration/dose administered intravenously, log (Cbrain/Ci.v.), was employed as a measure of the penetration ability of the imidazolidines into the brain. The octanol/buffer (pH = 7.4) system proved a satisfactory reference model in order to describe the transport process of the present imidazolidines from the blood to the brain. The penetration ability of these compounds into the brain could be expressed mathematically by a highly significant, parabolic relationship in log P'. Ideal lipophilic character for optimal brain concentrations is connected with a log P' value of 2.16.

Animals↗
PubMed2003

Concerns and coping with HIV: comparisons across groups.

To develop scales measuring major concerns about being HIV-positive and how people would cope with diagnosis, items were selected from the Ways of Coping Scale (Folkman et al., 1986)and generated by county health department HIV counsellors. Psychometric scale development involved two diverse samples of HIV test clients. Study I (health department, N = 272) yielded five Concerns with HIV scales and nine Coping with HIV scales. Factor structures did not differ between gay/bisexual men, heterosexual women or heterosexual men. In Study II (private non-profit gay-identified community HIV clinic, N = 227), LISREL confirmatory factor analyses cross-validated the Study I factor structures with no notable differences found. Some mean differences between genders and by sexual orientation were explained by different numbers of HIV-positive people known. Concern and Coping with HIV Scales (CCHIVS) are discussed for HIV/AIDS research and clinical use.

Adaptation, Psychological↗
PubMed2004

Sequence-based prediction of protein domains.

Guessing the boundaries of structural domains has been an important and challenging problem in experimental and computational structural biology. Predictions were based on intuition, biochemical properties, statistics, sequence homology and other aspects of predicted protein structure. Here, we introduced CHOPnet, a de novo method that predicts structural domains in the absence of homology to known domains. Our method was based on neural networks and relied exclusively on information available for all proteins. Evaluating sustained performance through rigorous cross-validation on proteins of known structure, we correctly predicted the number of domains in 69% of all proteins. For 50% of the two-domain proteins the centre of the predicted boundary was closer than 20 residues to the boundary assigned from three-dimensional (3D) structures; this was about eight percentage points better than predictions by 'equal split'. Our results appeared to compare favourably with those from previously published methods. CHOPnet may be useful to restrict the experimental testing of different fragments for structure determination in the context of structural genomics.

Computational Biology↗
PubMed1995

Structure analysis of breast lesions using neighborhood graphs.

The College of American Pathologists divides proliferative lesions of the breast into three categories, but the diagnostic criteria for classification are not easy to apply. Therefore, many morphologic, immunohistochemical and morphometric features were studied in order to clarify this subdivision; however, the reported results are not very satisfactory. We also attempted to identify and differentiate the architectural features useful for the diagnosis of proliferative breast lesions. The morphologic characteristics of proliferative lesions of the breast were considered amenable to a graph theoretical approach. From a set of images of mammary ducts acquired from a hematoxylin-eosin-stained section, a hierarchy of graphs was built. The main graphs representing the structure are: (1) neighborhood graph, (2) planar graph, derived from (1) and (3) a dual graph. A simplified prototype of a system for structure analysis of the lesions was implemented and tested. Forty duct images classified by two expert pathologists were acquired and subjected to the system. The data obtained were analyzed, and some significant graph features validating our approach to the structure representation of the lesions were discovered. This approach can also be applied to other, similar classification problems and may help in understanding the biologic significance of proliferative lesions of the breast.

Breast Neoplasms↗
PubMed2006

Validation study of the Turkish version of the Yale - Brown obsessive compulsive scale for heavy drinking in a group of male patients.

Psychometric properties of Turkish version of the Yale Brown Obsessive Compulsive Scale for heavy drinking (YBOCS-hd) were examined in alcohol-dependent male patients. Factor structure, internal consistency and discriminant validity of the YBOCS-hd were analysed in a sample of 117 male patients diagnosed with alcohol dependence. To study its convergent validity, the YBOCS-hd was correlated with the Addiction Severity Index in 34 of the patients. A test - retest reliability study was performed on the data from 34 patients. Correlation between the YBOCS-hd total score and the ASI Alcohol Use score was moderate (r = 0.51). One factor explained 50.2% of the variance. The YBOCS-hd was able to discriminate the groups abstinent for less than 1 month and a second group with at least 1 month of abstinence. Test - retest correlation was high (r = 0.81, ICC = 0.81). The Turkish version of the YBOCS-hd proved to be a reliable and valid instrument measuring craving in alcohol-dependent male individuals.

Alcohol Drinking↗
PubMed2003

Detecting psychosocial problems among 5-6-year-old children in preventive Child Health Care: the validity of a short questionnaire used in an assessment procedure for detecting psychosocial problems among children.

BACKGROUND: An extended re-assessment of the psychometric properties of the LSPPK, an instrument aimed at identifying children with emotional and behavioural problems. METHODS: Data came from a national sample in The Netherlands of parents of 1248 children (aged 5-6 years) interviewed by child health professionals (CHP). Data were obtained regarding psychosocial problems, treatment status and scores on the LSPPK (Parent and CHP Index), and on the Child Behavior Checklist (CBCL). The scale structure, reliability, criterion and content validity and added value of the LSPPK were assessed using the CBCL and treatment status as criteria. RESULTS: The scale structure corresponded with that found originally; the LSPPK improved the prediction of problems according to the CBCL, compared to predictions using readily available risk indicators alone. Reliability varied between 0.55 and 0.69. For the LSPPK Parent Index, sensitivity varied between 0.42 and 0.50. For the CHP Index sensitivity varied between 0.60 and 0.96, but specificity varied between 0.76 and 0.79. Both indices were very sensitive for attention and social problems, but less so for other problems. CONCLUSION: The LSPPK Parent Index cannot distinguish sufficiently between children with or without serious problems. Either too many children with problems remain unnoticed or too many children without problems are labelled as a case. The LSPPK CHP Index, reflecting the CHP's interpretation of the Parent Index after interviewing the parents does not compensate adequately for the weaknesses of the Parent Index. Better assessment procedures and strategies need to be developed.

Child↗