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PubMed2004

Determination of thermodynamic parameters for HIV DIS type loop-loop kissing complexes.

The HIV-1 type dimerization initiation signal (DIS) loop was used as a starting point for the analysis of the stability of Watson-Crick (WC) base pairs in a tertiary structure context. We used ultraviolet melting to determine thermodynamic parameters for loop-loop tertiary interactions and compared them with regular secondary structure RNA helices of the same sequences. In 1 M Na+ the loop-loop interaction of a HIV-1 DIS type pairing is 4 kcal/mol more stable than its sequence in an equivalent regular and isolated RNA helix. This difference is constant and sequence independent, suggesting that the rules governing the stability of WC base pairs in the secondary structure context are also valid for WC base pairs in the tertiary structure context. Moreover, the effect of ion concentration on the stability of loop-loop tertiary interactions differs considerably from that of regular RNA helices. The stabilization by Na+ and Mg2+ is significantly greater if the base pairing occurs within the context of a loop-loop interaction. The dependence of the structural stability on salt concentration was defined via the slope of a T(m)/log [ion] plot. The short base-paired helices are stabilized by 8 degrees C/log [Mg2+] or 11 degrees C/log [Na+], whereas base-paired helices forming tertiary loop-loop interactions are stabilized by 16 degrees C/log [Mg2+] and 26 degrees C/log [Na+]. The different dependence on ionic strength that is observed might reflect the contribution of specific divalent ion binding to the preformation of the hairpin loops poised for the tertiary kissing loop-loop contacts.

Base Pairing↗
PubMed2006

The development of children's ideal and ought self-guides: parenting, temperament, and individual differences in guide strength.

Regulatory focus theory (RFT; Higgins, 1997) predicts that individual differences in the strength of promotion (ideal) and prevention (ought) orientations emerge from patterns of parent/child interactions that emphasize making good things happen versus keeping bad things from happening. This article examines the development of individual differences in the strength of children's promotion and prevention goals and presents selected findings from three studies exploring the origins of regulatory focus. We found a three-factor structure for parenting behaviors that differentiated between the presence/absence of positive outcomes versus the presence/absence of negative outcomes in two different data sets and validated that factor structure by examining its associations with maternal temperament. In turn, the parenting factors predicted individual differences in children's orientations to ideal and ought guides, and those associations were moderated by individual differences in child temperament.

Child↗
PubMed1995

The Pain Beliefs and Perceptions Inventory: a British replication.

The factorial structure, reliability, and validity of the Pain Beliefs and Perceptions Inventory (PBPI) was investigated in a sample of 84 pain patients drawn from a pain clinic in the United Kingdom. The recovered factorial structure replicated that of a previous study. The 4 derived subscales, Mysteriousness, Self-Blame, Pain Constancy and Pain Permanence, had excellent reliability (internal consistency); Chronbach's alpha was greater than 0.80. However, the construct validity of the PBPI, assessed by examining the association between the subscales and the Coping Strategies Questionnaire (CSQ), was not supported. The results are discussed with particular reference to the interpretative issues concerning 2 of the subscales and their relation to the concept of the 'time line' component of illness representation.

Adaptation, Psychological↗
PubMed2005

Drinking refusal self-efficacy questionnaire-revised (DRSEQ-R): a new factor structure with confirmatory factor analysis.

The drinking refusal self-efficacy questionnaire (DRSEQ) assesses a person's belief in their ability to resist alcohol. The DRSEQ is a sound psychometric instrument based on exploratory factor analyses, but has not been subjected to confirmatory factor analysis. In total 2773 participants were used to confirm the factor structure of the DRSEQ. Initial analyses revealed that the original structure was not confirmed in the current study. Subsequent analyses resulted in a revised factor structure (DRSEQ-R) being confirmed in community, student and clinical samples. The DRSEQ-R was also found to have good construct and concurrent validity. The factor structure of the DRSEQ-R is more stable than the original structure of the DRSEQ and the revised scale has considerable potential in future alcohol-related research.

Adult↗
PubMed2003

Mutational analysis defines the roles of conserved amino acid residues in the predicted catalytic pocket of the rRNA:m6A methyltransferase ErmC'.

Methyltransferases (MTases) from the Erm family catalyze S-adenosyl-L-methionine-dependent modification of a specific adenine residue in bacterial 23S rRNA, thereby conferring resistance to clinically important macrolide, lincosamide and streptogramin B antibiotics. Despite the available structural data and functional analyses on the level of the RNA substrate, still very little is known about the mechanism of rRNA:adenine-N(6) methylation. Only predictions regarding various aspects of this reaction have been made based on the analysis of the crystal structures of methyltransferase ErmC' (without the RNA) and their comparison with the crystallographic and biochemical data for better studied DNA:m(6)A MTases. To validate the structure-based predictions of presumably essential residues in the catalytic pocket of ErmC', we carried out the site-directed mutagenesis and studied the function of the mutants in vitro and in vivo. Our results indicate that the active site of rRNA:m(6)A MTases is much more tolerant to amino acid substitutions than the active site of DNA:m(6)A MTases. Only the Y104 residue implicated in stabilization of the target base was found to be indispensable. Remarkably, the N101 residue from the "catalytic" motif IV and two conserved residues that form the floor (F163) and one of the walls (N11) of the base-binding site are not essential for catalysis in ErmC'. This somewhat surprising result is discussed in the light of the available structural data and in the phylogenetic context of the Erm family.

Adhesins, Bacterial↗
PubMedDate not supplied

Reliability and validity of dyspnea sensory quality descriptors in heart failure patients treated in an emergency department.

BACKGROUND: Sensory qualities of dyspnea are known to differ by diagnosis. Less is known about whether sensory qualities vary with changes in health status in a given diagnosis. PURPOSE: The goal of this study was to evaluate the reliability, validity, and factor structure of dyspnea sensory quality descriptors in patients with heart failure (HF) treated in an emergency department (ED) and to investigate whether change in sensory quality influences HF patients to seek care in an ED. METHODS: HF patients (N = 57) treated in an ED were interviewed retrospectively. Open-ended characterizations of dyspnea at the time of the ED visit were analyzed qualitatively. A subset of subjects (n = 34) rated the intensity of 13 dyspnea descriptors (0 = not endorsed; 1= very mild; 10 = very severe) as the descriptors applied to the time at which they decided to come to the ED (Decision) and a week before the visit (Week Before). Descriptor ratings were analyzed for congruence with open-ended characterizations, endorsement frequency, internal consistency, factor structure, and correlations (by descriptor and within subjects) between the 2 time frames. RESULTS: Open-ended characterizations of dyspnea provided support for the content validity of most descriptors. Internal consistency of numerical ratings was high (alpha >0.90) in both recalled time frames. Factor analysis of descriptor ratings was unifactorial for Week Before, but suggested multiple sensory quality factors at Decision (suffocation, air hunger, effort/impedance, and, possibly, rate). Within-subject concordance and descriptor-by-descriptor correlations across time frames were mostly low, suggesting change in sensory quality from Week Before to Decision. Correlations in descriptor ratings were lowest among subjects who reported duration of dyspnea (as severe as at Decision) of 3 days or less. Subjects who recalled a duration of 6 days or more gave highly concordant ratings across both time frames. CONCLUSION: Sensory quality descriptor-based ratings were internally consistent and content valid. Low correlations in ratings of sensory quality for most subjects across recalled time frames suggest that change in sensory quality may be an aspect of perceived increases in dyspnea severity before an ED visit. Results require replication and extension with larger samples and other diagnoses.

Dyspnea↗
PubMed2000

Investigation of active structural intensity control in finite beams: theory and experiment

An investigation of structural intensity control is presented in this paper. As opposed to previous work, the instantaneous intensity is completely taken into account in the control algorithm, i.e., all the terms are considered in the real-time control process and, in particular, the evanescent waves are considered in this approach. A finite difference approach using five accelerometers is used as the sensing scheme. A feedforward filtered-X least mean square algorithm is adapted to this energy-based control problem, involving a nonpositive definite quadratic form in general. In this respect, the approach is limited to cases where the geometry is such that the intensity component will have the same sign for the control source and the primary disturbance. Results from numerical simulations are first presented to illustrate the benefit of using a cost function based on structural intensity. Experimental validation of the approach is conducted on a free-free beam covered with viscoelastic material. A comparison is made between classical acceleration control and structural intensity control and the performance of both approaches is presented. These results confirm that using intensity control allows the error sensors to be placed closer to the control source and the primary disturbance, while preserving a good control performance.

Journal Article↗
PubMed2007

Validity and reliability of patient satisfaction questionnaires in a dental school in Japan.

PURPOSE: The purpose of this study was to construct questionnaires for the dental school setting from freely given patient answers with the aid of text mining, and to confirm the structure, reliability and validity of the questionnaires. METHODS: Using these questionnaires, we carried out a survey of the satisfaction of patients treated at the Dental Hospital of the Tsurumi University School of Dental Medicine. A total of 3394 patients participated in the study. To confirm the reliability of inter-item correlations and construct validity, factor analysis was carried out, and items belonging to each factor and Cronbach's alpha coefficients were calculated. RESULTS: Four factors were extracted and 64.0% of the variance was explained by these four factors. All correlation coefficients were >0.85. These four factors were: 'Treatment', 'Communication', 'Facilities' and 'Appearances'. From structural equation modelling, we determined that overall satisfaction was >0.75 and was statistically significant. CONCLUSION: The questionnaires used in this study are useful for measuring patient satisfaction in the dental school hospital setting.

Adolescent↗
PubMed1998

The structure of serine hydroxymethyltransferase as modeled by homology and validated by site-directed mutagenesis.

We describe a model for the three-dimensional structure of E. coli serine hydroxymethyltransferase based on its sequence homology with other PLP enzymes of the alpha-family and whose tertiary structures are known. The model suggests that certain amino acid residues at the putative active site of the enzyme can adopt specific roles in the catalytic mechanism. These proposals were supported by analysis of the properties of a number of site-directed mutants. New active site features are also proposed for further experimental testing.

Amino Acid Sequence↗
PubMed1986

On drawing inferences about the structure of normal cognitive systems from the analysis of patterns of impaired performance: the case for single-patient studies.

An analysis of the logic of valid inferences about the structure of normal cognitive processes from the study of impaired cognitive performance in brain-damaged patients is presented. The logic of inferences from group studies and single-case studies is compared. It is shown that given certain assumptions, only the single-case method allows valid inferences about the structure of cognitive systems from the analysis of impaired performance. It is also argued that although the single-case approach is not entirely problem-free, the difficulties encountered are relatively minor.

Brain Damage, Chronic↗
PubMed2006

Evaluation of sequence alignments and oligonucleotide probes with respect to three-dimensional structure of ribosomal RNA using ARB software package.

BACKGROUND: Availability of high-resolution RNA crystal structures for the 30S and 50S ribosomal subunits and the subsequent validation of comparative secondary structure models have prompted the biologists to use three-dimensional structure of ribosomal RNA (rRNA) for evaluating sequence alignments of rRNA genes. Furthermore, the secondary and tertiary structural features of rRNA are highly useful and successfully employed in designing rRNA targeted oligonucleotide probes intended for in situ hybridization experiments. RNA3D, a program to combine sequence alignment information with three-dimensional structure of rRNA was developed. Integration into ARB software package, which is used extensively by the scientific community for phylogenetic analysis and molecular probe designing, has substantially extended the functionality of ARB software suite with 3D environment. RESULTS: Three-dimensional structure of rRNA is visualized in OpenGL 3D environment with the abilities to change the display and overlay information onto the molecule, dynamically. Phylogenetic information derived from the multiple sequence alignments can be overlaid onto the molecule structure in a real time. Superimposition of both statistical and non-statistical sequence associated information onto the rRNA 3D structure can be done using customizable color scheme, which is also applied to a textual sequence alignment for reference. Oligonucleotide probes designed by ARB probe design tools can be mapped onto the 3D structure along with the probe accessibility models for evaluation with respect to secondary and tertiary structural conformations of rRNA. CONCLUSION: Visualization of three-dimensional structure of rRNA in an intuitive display provides the biologists with the greater possibilities to carry out structure based phylogenetic analysis. Coupled with secondary structure models of rRNA, RNA3D program aids in validating the sequence alignments of rRNA genes and evaluating probe target sites. Superimposition of the information derived from the multiple sequence alignment onto the molecule dynamically allows the researchers to observe any sequence inherited characteristics (phylogenetic information) in real-time environment. The extended ARB software package is made freely available for the scientific community via http://www.arb-home.de.

Algorithms↗
PubMed2006

Towards patient-centered health services in India--a scale to measure patient perceptions of quality.

OBJECTIVE: . (i) To develop a reliable and valid scale to measure in-patient and outpatient perceptions of quality in India and (ii) to identify aspects of perceived quality which have large effects on patient satisfaction. DESIGN: Cross-sectional survey of health facilities and patients at clinics. SETTING: Primary health centers, community health centers, district hospitals, and female district hospitals in the state of Uttar Pradesh in north India. MAIN OUTCOME MEASURES: Internal consistency, validity, and factor structure of the scale are evaluated. The association between patient satisfaction and perceived quality dimensions is examined. RESULTS: A 16-item scale having good reliability and validity is developed. Five dimensions of perceived quality are identified-medicine availability, medical information, staff behavior, doctor behavior, and hospital infrastructure. Patient perceptions of quality at public health facilities are slightly better than neutral. Multivariate regression analysis results indicate that for outpatients, doctor behavior has the largest effect on general patient satisfaction followed by medicine availability, hospital infrastructure, staff behavior, and medical information. For in-patients, staff behavior has the largest effect followed by doctor behavior, medicine availability, medical information, and hospital infrastructure. CONCLUSIONS: The scale developed can be used to measure perceived quality at a range of facility types for outpatients and in-patients. Perceived quality at public facilities is only marginally favorable, leaving much scope for improvement. Better staff and physician interpersonal skills, facility infrastructure, and availability of drugs have the largest effect in improving patient satisfaction at public health facilities.

Adult↗
PubMed2006

Living with primary ciliary dyskinesia: a prospective qualitative study of knowledge sharing, symptom concealment, embarrassment, mistrust, and stigma.

BACKGROUND: Primary ciliary dyskinesia (PCD) is a chronic respiratory disease for which there is little psycho-social research and no qualitative studies of individuals living with the condition. A questionnaire-based survey in 2003 found evidence of stigmatisation in some individuals with PCD. Although the questionnaire had face and construct validity, stigmatisation was not cross-validated against interviews. The present study had the twin aims of carrying out a qualitative study of the adult patients living with PCD, and using a structured design to validate the questionnaire measure of stigma. METHODS: Interviews were carried out with six pairs of individuals with PCD, matched for sex, situs, and age, one with a high stigma score in 2003 and the other with a low stigma score. Depth-qualitative interviews were conducted by one author to explore themes surrounding the psycho-social impact of PCD using a grounded theory analysis. The interviewer was blind to the stigma scores of participants, and after the qualitative analysis was completed, the interviewer made an assessment of which member of each pair seemed the more stigmatised, after which the code was broken. RESULTS: Interviews revealed a number of themes, including other people's knowledge of PCD, the sharing of knowledge about PCD, the concealment of symptoms of PCD, embarrassment at symptoms, changes of behaviour in response to PCD, mistrust of medical care, in particular in relation to problems in diagnosis, a mistrust of general practitioners who were seen as poorly informed, and the importance of expert care at tertiary referral centres. Although stigmatisation as such was rarely mentioned directly by respondents, when the interviewer's judgement on level of stigmatisation was correlated with stigma scores from 2003, it was found that the more stigmatised member had been correctly identified in all six pairs (p = .016). CONCLUSION: Our results suggest that some people with PCD feel isolated through mistrust in medicine, and lack of knowledge surrounding PCD. Many responses to PCD can be explained in terms of stigmatisation, and in particular felt stigma. The correlation between questionnaire used several years previously, and the interviewer's judgements of stigmatisation suggest that the stigma questionnaire had both predictive validity and long-term stability. As in other chronic conditions, stigmatisation occurs only in some individuals with PCD, and the present study explores the basis of stigmatisation, and validate the questionnaire as a measure of difference in stigma.

Adult↗
PubMed1993

[Surgical technical principles of trans-scleral suture of posterior chamber lenses].

BACKGROUND: Most reports on transscleral suture fixation of posterior chamber lenses (PCL) do not mention the principal difficulty that the surgeon has no valid information which structures were perforated by the needle and where he happened to fix the PCL loops. To know this exactly is a "conditio sine qua non". Without it, no valid evaluation of longterm results of this method will ever be possible. MATERIALS AND METHODS: Thirtythree PCL were fixated by transscleral suturing. The results of the decisive surgical steps were controlled by intraoperative endoscopy. The experiences and insights gained thereby were used to develop step by step optimal surgical procedures for different conditions. The results of the endoscopically controlled group were compared with the results of 128 eyes with transscleral suture fixation of a PCL without endoscopic control between 6/88 and 4/91. RESULTS: On the basis of systematically performed endoscopic controls during surgery we have identified several faults and pitfalls which should be avoided. In consequence we have developed rules and items that should be fulfilled in order to arrive at an anatomically correct position of the PCL: 1. The transscleral suture should only penetrate the sulcus and no adjacent structures of the iris or the ciliary processes. 2. The PCL loops must be primarily directed into the sulcus, 3. PCL design must be adapted to the anatomical needs of the procedure and must provide a safe distance between iris and PCL to avoid iris-shafting. Detailed suggestions are given to fulfil these requirements. The most important point is the two-step implantation of the PCL out of the anterior chamber into the posterior chamber to avoid a steep and disadvantageous implantation angle. Up to date, no cases with chronic intraocular inflammation have occurred in the endoscopically controlled group in contrast to the earlier non-controlled group. CONCLUSIONS: Our results allow--even without endoscopic control--an exact positioning of the PCL hepatics in the sulcus, which is the most important step in the whole procedure. However, for a scientific evaluation of longterm results after transscleral suturing of PCL endoscopic control will further be needed to demonstrate or to rule out any potentially harmful compression of the ciliary body or iris structures and to see whether or not such irregularities will be associated with reduced longterm tolerance.

Endoscopes↗
PubMed1999

Validation of the coping with health, injuries, and problems scale in a chronic pain sample.

OBJECTIVE: The Coping with Health, Injuries, and Problems (CHIP) Scale is a self-report instrument that is designed for diverse patient populations to provide measures of emotion-focused (e.g., emotional preoccupation) and task-oriented (e.g., palliative, instrumental, distraction) responses to injury. The present investigation assessed the factor structure, reliability, and validity of the measure in patients (n = 203) with chronic musculoskeletal pain. METHOD: Patients were administered questionnaires, including the CHIP Scale, and measures of pain coping strategies, adjustment, and personality. RESULTS: The factor structure, with one exception, was replicable, and the subscale reliabilities were acceptable. The subscales related in predictable ways to other similar questionnaires, to pain adjustment, and to personality. CONCLUSION: Overall, the CHIP Scale is both reliable and valid in assessing responses to chronic pain. Researchers and clinicians who want to use a psychometrically sound measure of response to illness that is applicable across diverse patient populations are encouraged to consider this measure.

Adaptation, Psychological↗
PubMed2002

Quantitative structure-mobility relationship modelling of electrokinetic chromatography of metal complexes: approaches and limitations.

A charged surfactant or an ionic polymer added to the capillary electrolyte introduces micellar solubilization and ion-exchange interactions, respectively, as a supplementary separation principle for metal complexes among a great many other analytes. Acting as a pseudostationary phase, such electrolyte additives make the separation mechanism fairly different from that based only on differences in electrophoretic mobility. A range of quantitative structure-mobility relationships were developed to explain the migration behavior of metal complexes in micellar and ion-exchange electrokinetic chromatographic systems as a function of their primary structural parameters. The validity of migration models tested using a comprehensive selection of experimental data available in the literature was shown to depend significantly on the judicious choosing of the analyte structural descriptors and on the dominance of either of the electrophoretic mobility of the analyte, partitioning into the micelle, and the ion-exchange interaction with the polymer. In the systems where the separation mechanism is dominated by neither chromatography nor electrophoresis, their relative contributions were accounted for by the degree of correlation between experimental and calculated mobilities and by variations in the absolute value and sign of regression coefficients at the most influencing parameters.

Chromatography, Ion Exchange↗
PubMed1984

Convergent validity of type A behavior pattern scales and their ability to predict physiological responsiveness in a sample of female public employees.

The purpose of this study was to assess the construct validity of the structured interview (SI), Jenkins Activity Survey (JAS), Thurstone Activity Scale, and Bortner Type A Scale in a sample of female employees from a government service agency. Criteria for validity assessment were physiological reactance to a mental stressor, psychological strains experienced at work, physical symptoms associated with work, and urinary catecholamine production at work. A continuous Type A SI scale demonstrated better convergent and construct validity than did the SI category scores. All of the SI Type A scales were reliable. Among the questionnaire measures only the Thurstone Activity Scale was reliable and showed the strongest construct validity. The SI measures of Type A tended to correlate with physiological responsiveness (changes in heart rate, skin temperature, and skin conductance), while the questionnaire measures correlated with self-reports of job strains (satisfaction, irritation, depression, physical symptoms), thus indicating the operation of measurement artifacts in validity assessment. No significant correlations were obtained between Type A and catecholamines. Comparison of correlation analysis with subgroup analysis revealed the former to be a more powerful test of the relationships that may exist between Type A behavior pattern and relevant criteria.

Adult↗
PubMed2002

Pharmacophore mapping of a series of 2,4-diamino-5-deazapteridine inhibitors of Mycobacterium avium complex dihydrofolate reductase.

Pharmacophore hypotheses were developed for a series of 2,4-diamino-5-deazapteridine inhibitors of Mycobacterium avium complex (MAC) and human dihydrofolate reductase (hDHFR). Training sets consisting of 20 inhibitors were selected in each case on the basis of the information content of the structures and activity data as required by the HypoGen program in the Catalyst software. In the case of MAC DHFR inhibitors, the best pharmacophore in terms of statistics and predictive value consisted of four features: two hydrogen bond acceptors (HA), one hydrophobic (HY) feature, and one ring aromatic (RA) feature. The selected pharmacophore hypothesis yielded an rms deviation of 0.730 and a correlation coefficient of 0.967 with a cost difference (null cost minus total cost) of approximately 52. The pharmacophore was validated on a large set of test inhibitors. For the test series, a classification scheme was used to distinguish highly active from moderately active and inactive compounds on the basis of activity ranges. This classification scheme is more practical than actual estimated values because these values have no meaning for compounds yet to be tested except that they indicate whether the compounds will be active or inactive in a biological assay. For the training set, the success rate for predicting active and inactive compounds was 100%. For the test set, the success rate in predicting active compounds was greater than 92% while about 7% of the inactive compounds were predicted to be active. This successful prediction was further validated on three structurally diverse compounds active against MAC DHFR. Two compounds mapped well onto three of the four features of the pharmacophore. The third compound was mapped to all four features of the pharmacophore. This validation study provided confidence for the usefulness of the selected pharmacophore model to identify compounds with diverse structures from a database search. Comparison of pharmacophores for inhibitors of human and MAC DHFR is expected to reveal fundamental differences between these two pharmacophores that may be effectively exploited to identify and design compounds with high selectivity for MAC DHFR.

Folic Acid Antagonists↗