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PubMed1998

Error structure for the HPLC analysis for atenolol, metoprolol and propranolol: a useful weighting method in parameter estimation.

Three reversed-phase high performance liquid chromatography (HPLC) methods with UV detection were developed and fully validated for the quantification of three beta-blockers: atenolol, metoprolol and propranolol. After validation, error structures for the HPLC analysis were established using a convenient and practical procedure. The mean percentage of relative standard deviation (RSD) of the experimental concentrations (C), were less than 4.29% for proportionality and less than 3.68% for precision for any of the drugs, which allowed the quantitation of beta-blockers assayed at concentrations in the range 25-0.78 micrograms.ml-1. The error structures for the HPLC analysis were: SD (micrograms.ml-1) = 5.02 x 10(-2) C for atenolol, SD (micrograms.ml-1) = 4.55 x 10(-2) + 0.63 x 10(-2) C - 7.58 x 10(-6) C3 for metoprolol and SD (micrograms.ml-1) = 2.73 x 10(-2) C - 3.49 x 10(-4) C2 for propranolol. The reciprocal of the square of the SD of the drug concentrations measured within the calibration curve could be used as weighting methods in parameter estimation by non-linear regression.

Adrenergic beta-Antagonists↗
PubMed1996

The development of a measure of enculturation for Native American youth.

Enculturation is the process by which individuals learn about and identify with their ethnic minority culture. It is distinguished from acculturation which refers to the process by which an ethnic minority individual is assimilated into the majority culture. Three studies with Native American youths are reported that describe the development of a measure of enculturation for Native American youths. Development of a measure of enculturation provides a foundation upon which to build a body of literature that focuses on strengths in a youth's life rather than on deficits. Results of the first study (n = 120), a confirmatory factor analysis, indicated that cultural affinity, native American identity, and family involvement in traditional activities adequately represent the construct of ecnulturation. The study also provides some convergent validity for this interpretation. The second study examines factor invariance for enculturation among youths with data from over 2 years (n = 69). The factor structure was similar across time. The third study replicates the factor structure and validity analyses with a new sample (n = 42). Usefulness of the measure for assessing protective factors and stressing ethnicity over simple assessment of race categories is discussed.

Adolescent↗
PubMed2005

The development, validity and reliability of a multimodality objective structured clinical examination in psychiatry.

OBJECTIVES: To evaluate the development, validity and reliability of a multimodality objective structured clinical examination (OSCE) in undergraduate psychiatry, integrating interactive face-to-face and telephone history taking and communication skills stations, videotape mental state examinations and problem-oriented written stations. METHODS: The development of the OSCE on a restricted budget is described. This study evaluates the validity and reliability of 4 15-18-station OSCEs for 128 students over 1 year. Face and content validity were assessed by a panel of clinicians and from feedback from OSCE participants. Correlations with consultant clinical 'firm grades' were performed. Interrater reliability and internal consistency (interstation reliability) were assessed using generalisability theory. RESULTS: The OSCE was feasible to conduct and had a high level of high perceived face and content validity. Consultant firm grades correlated moderately with scores on interactive stations and poorly with written and video stations. Overall reliability was moderate to good, with G-coefficients in the range 0.55-0.68 for the 4 OSCEs. CONCLUSIONS: Integrating a range of modalities into an OSCE in psychiatry appears to represent a feasible, generally valid and reliable method of examination on a restricted budget. Different types of stations appear to have different advantages and disadvantages, supporting the integration of both interactive and written components into the OSCE format.

Clinical Competence↗
PubMed2001

Practice parameter: diagnosis of dementia (an evidence-based review). Report of the Quality Standards Subcommittee of the American Academy of Neurology.

OBJECTIVE: To update the 1994 practice parameter for the diagnosis of dementia in the elderly. BACKGROUND: The AAN previously published a practice parameter on dementia in 1994. New research and clinical developments warrant an update of some aspects of diagnosis. METHODS: Studies published in English from 1985 through 1999 were identified that addressed four questions: 1) Are the current criteria for the diagnosis of dementia reliable? 2) Are the current diagnostic criteria able to establish a diagnosis for the prevalent dementias in the elderly? 3) Do laboratory tests improve the accuracy of the clinical diagnosis of dementing illness? 4) What comorbidities should be evaluated in elderly patients undergoing an initial assessment for dementia? RECOMMENDATIONS: Based on evidence in the literature, the following recommendations are made. 1) The DSM-III-R definition of dementia is reliable and should be used (Guideline). 2) The National Institute of Neurologic, Communicative Disorders and Stroke--AD and Related Disorders Association (NINCDS-ADRDA) or the Diagnostic and Statistical Manual, 3rd edition, revised (DSM-IIIR) diagnostic criteria for AD and clinical criteria for Creutzfeldt--Jakob disease (CJD) have sufficient reliability and validity and should be used (Guideline). Diagnostic criteria for vascular dementia, dementia with Lewy bodies, and frontotemporal dementia may be of use in clinical practice (Option) but have imperfect reliability and validity. 3) Structural neuroimaging with either a noncontrast CT or MR scan in the initial evaluation of patients with dementia is appropriate. Because of insufficient data on validity, no other imaging procedure is recommended (Guideline). There are currently no genetic markers recommended for routine diagnostic purposes (Guideline). The CSF 14-3-3 protein is useful for confirming or rejecting the diagnosis of CJD (Guideline). 4) Screening for depression, B(12) deficiency, and hypothyroidism should be performed (Guideline). Screening for syphilis in patients with dementia is not justified unless clinical suspicion for neurosyphilis is present (Guideline). CONCLUSIONS: Diagnostic criteria for dementia have improved since the 1994 practice parameter. Further research is needed to improve clinical definitions of dementia and its subtypes, as well as to determine the utility of various instruments of neuroimaging, biomarkers, and genetic testing in increasing diagnostic accuracy.

Dementia↗
PubMed1998

Extensible markup language (XML) in health care: integration of structured reporting and decision support.

The Extensible Markup Language (XML) is a newly adopted Internet protocol for data interchange designed to bring the key features of the Standard Generalized Markup Language (SGML; ISO 8879:1986)--extensibility, complex structures, and validation--to the World Wide Web. In this paper, we describe an architecture that uses XML to mediate between disparate client-server systems for structured reporting and decision support.

Bayes Theorem↗
PubMed2000

Assigning genomic sequences to CATH.

We report the latest release (version 1.6) of the CATH protein domains database (http://www.biochem.ucl. ac.uk/bsm/cath ). This is a hierarchical classification of 18 577 domains into evolutionary families and structural groupings. We have identified 1028 homo-logous superfamilies in which the proteins have both structural, and sequence or functional similarity. These can be further clustered into 672 fold groups and 35 distinct architectures. Recent developments of the database include the generation of 3D templates for recognising structural relatives in each fold group, which has led to significant improvements in the speed and accuracy of updating the database and also means that less manual validation is required. We also report the establishment of the CATH-PFDB (Protein Family Database), which associates 1D sequences with the 3D homologous superfamilies. Sequences showing identifiable homology to entries in CATH have been extracted from GenBank using PSI-BLAST. A CATH-PSIBLAST server has been established, which allows you to scan a new sequence against the database. The CATH Dictionary of Homologous Superfamilies (DHS), which contains validated multiple structural alignments annotated with consensus functional information for evolutionary protein superfamilies, has been updated to include annotations associated with sequence relatives identified in GenBank. The DHS is a powerful tool for considering the variation of functional properties within a given CATH superfamily and in deciding what functional properties may be reliably inherited by a newly identified relative.

Amino Acid Sequence↗
PubMed1997

New finite difference formulations for general inhomogeneous anisotropic bioelectric problems.

Due to its low computational complexity, finite difference modeling offers a viable tool for studying bioelectric problems, allowing the field behavior to be observed easily as different system parameters are varied. Previous finite difference formulations, however, have been limited mainly to systems in which the conductivity is orthotropic, i.e., a strictly diagonal conductivity tensor. This in turn has limited the effectiveness of the finite difference, technique in modeling complex anatomies with arbitrarily anisotropic conductivities, e.g., detailed fiber structures of muscles where the fiber can lie in any arbitrary direction. In this paper, we present both two-dimensional and three-dimensional finite difference formulations that are valid for structures with an inhomogeneous and nondiagonal conductivity tensor. A data parallel computer, the connection machine CM-5, is used in the finite difference implementation to provide the computational power and memory for solving large problems. The finite difference grid is mapped effectively to the CM-5 by associating a group of nodes with one processor. Details on the new approach and its data parallel implementation are presented together with validation and computational performance results. In addition, an application of the new formulation in providing the potential distribution inside a canine torso during electrical defibrillation is demonstrated.

Algorithms↗
PubMed2006

Three dimensional stereolithography models of cancellous bone structures from muCT data: testing and validation of finite element results.

Stereolithography (STL) models of complex cancellous bone structures have been produced from three-dimensional micro-computed tomography data sets of human cancellous bone histological samples from four skeletal sites. The STL models have been mechanically tested and the derived stiffness compared with that predicted by finite element analysis. The results show a strong correlation (R2 = 0.941) between the predicted and calculated stiffnesses of the structures and show promise for the use of STL as an additional technique to complement the use of finite element models, for the assessment of the mechanical properties of complex cancellous bone structures.

Biomimetics↗
PubMed1997

Probing the structure of the HIV-1 Rev trans-activator protein by functional analysis.

Human immunodeficiency virus type 1 (HIV-1) encodes a trans-acting regulatory protein, termed Rev, which is critically required for virus replication. Rev is a sequence-specific RNA binding protein which mediates the nuclear export of unspliced and incompletely spliced viral mRNAs encoding the viral structural proteins. While CD and fluorescence measurements have provided several possible structural models of Rev, all attempts employing X-ray crystallography and NMR techniques have so far failed to provide more accurate data. We present a new approach to validate alternative structural models of the N-terminal region of Rev which contains the nuclear localization/RNA binding domain. Points of contact between structural elements in a protein were determined by introduction of targeted amino acid substitutions and subsequent scoring of the biological activities. Our data resulted in the suggestion of a new and more refined model of HIV-1 Rev structure which to date has been impossible to obtain by other means.

Animals↗
PubMed1999

Development and preliminary validation of a semi-structured interview for the screening of law enforcement candidates.

A standard practice among most law enforcement agencies is to include psychological screening in the selection of job candidates. Although the use of personality tests in predicting job performance of law enforcement officers has received empirical support (e.g., the Minnesota Multiphasic Personality Inventory, the Inwald Personality Inventory), there is a conspicuous absence of data regarding the reliability and validity of interview procedures. The present study represents the first step in the development of a standardized, semi-structured interview for use in the screening of law enforcement personnel. This interview, the Law Enforcement Candidate Interview, was constructed using content areas drawn from measures used in the screening of law enforcement personnel (e.g., Inwald Personality Inventory) and assessment of personality functioning (Structured Clinical Interview for DSM-III-R Personality Disorders). This interview was then administered by two doctoral students to a group of law enforcement academy cadets (n=34). A modest degree of inter-rater reliability was achieved, although internal consistency was somewhat lacking. Interview scores were correlated with measures of academy performance (final grade-point average and peer and supervisor ranking of academy performance). Results of these analyses suggest the LECI is a modest predictor of academy performance. Potential uses of the LECI and future research indications are outlined.

Adult↗
PubMed2006

Virtual screening for environmental pollutants: structure-activity relationships applied to a database of industrial chemicals.

The current risk paradigm calls for individual consideration and evaluation of each separate environmental pollutant, but this does not reflect accurately the cumulative impact of anthropogenic chemicals. In the present study, previously validated structure-activity relationships were used to estimate simultaneously the baseline toxicity and atmospheric persistence of approximately 50,000 compounds. The results from this virtual screening indicate fairly stable statistical distributions among small anthropogenic compounds. The baseline toxicity was not changed much by halogen substitution, but a distinct increase seemed to occur in the environmental persistence with increased halogenation. The ratio of the atmospheric half-lives to the median lethal concentrations provides a continuous scale with which to rank and summarize the incremental environmental impacts in a mixture-exposure situation. Halogenated compounds as a group obtained a high ranking in this data set, with well-known pollutants at the very top: DDT metabolites and derivatives, polychlorinated biphenyls, diphenyl ethers and dibenzofurans, chlorinated paraffins, chlorinated benzenes and derivatives, hydrochlorofluorocarbons, and dichlorononylphenol. Environmentally friendly chemicals that obtained the lowest rank are nearly all hydroxylated and water-soluble. Virtual screening can assist with "green chemistry" in designing safe and degradable products and enable assessment of the efficiency in chemicals risk management.

Chemical Industry↗
PubMed2006

Validation study of the Multicultural Quality of Life Index (MQLI) in a Peruvian sample.

OBJECTIVE: The Multicultural Quality of Life Index is a concise instrument for comprehensive, culture-informed, and self-rated assessment of health-related quality of life. It is composed of 10 items (from physical well-being to global perception of quality of life). Each item is rated on a 10-point scale. The objective was to evaluate the reliability (test-retest), internal structure, discriminant validity, and feasibility of the Multicultural Quality of Life Index in Lima, Peru. METHOD: The reliability was studied in general medical patients (n = 30) hospitalized in a general medical ward. The Multicultural Quality of Life Index was administered in two occasions and the correlation coefficients ("r") between both interviews were calculated. Its discriminant validity was studied statistically comparing the average score in a group of patients with AIDS (with presumed lower quality of life, n = 50) and the average score in a group of dentistry students and professionals (with presumed higher quality of life, n = 50). Data on its applicability and internal structure were compiled from the 130 subjects. RESULTS: A high reliability correlation coefficient (r = 0.94) was found for the total score. The discriminant validity study found a significant difference between mean total score in the samples of presumed higher (7.66) and lower (5.32) quality of life. The average time to complete the Multicultural Quality of Life Index was less than 4 minutes and was reported by the majority of subjects as easily applicable. A high Cronbach's a (0.88) was also documented. CONCLUSIONS: The results reported that the Multicultural Quality of Life Index is reliable, has a high internal consistency, is capable of discriminating groups of presumed different quality of life levels, is quite efficient, and easy to use.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Regional cerebral blood flow in pigs estimated by microspheres.

Regional cerebral blood flow in anaesthetized pigs is determined with the microsphere method. Five regions of cortical grey matter and three white subcortical areas in each hemisphere are examined together with anatomically classic structures. The validity of the biopsies was confirmed by freeze drying of the tissue. Three flow measurements in a group of six animals showed large interindividual variations whereas regions with the same structure in the particular animal showed a high degree of uniformity. Symmetrical regions in the two hemispheres were similar with a coefficient of variation between sides of less than 5%. The coefficient of variation of the particular flow measurements were 15%. The different brain structures have four discernible flow levels. White subcortical matter has three different flow values and forms together with medulla oblongata and hippocampus the low flow area. Flow in grey cortical matter is of the same magnitude as in unanaesthetized animals and constitutes together with thalamus, mesencephalon, pons and cerebellar hemispheres the intermediate flow level. The high flow areas are nucleus caudatus and lentiformis together with the cerebellar vermis. The choroid plexus, pituitary gland and pineal gland all have very high flow values and seem, in contrast to the rest of the brain, insensitive to the CO2-tension in arterial blood and global cerebral metabolism. Microsphere estimation of regional blood flow seems to be an appropriate technique for evaluating regional cerebral blood with a high degree of spatial resolution in repeated flow measurements.

Animals↗
PubMed1979

A factor-analytic examination of the unitary OR concept.

Recent studies have generated a four-system structure proposed as a replacement for Sokolov's unitary OR concept. This conceptualisation developed from a logical consideration of stimulus--response relationships based upon mean response magnitudes over subjects, and paid no attention to individual response types. It is conceivable that no individual subject exhibited responses compatible with such a formulation. This paper addressed that problem by using factor analysis as a means of descriptively summarising the data of each subject, and examining its compatibility with both unitary and four-system structures. Of 72 subjects, none exhibited a factor structure compatible with Sokolov's unitary concept, while 70 exhibited structures compatible with the four-system structure. These results support the validity of the structure proposed to replace the unitary OR.

Arousal↗
PubMed2003

Validity of self-report screening scale for elder abuse: Women's Health Australia Study.

PURPOSE: Early identification of elder abuse requires a valid, easily administered screening instrument. This study examined the reliability and validity of the Vulnerability to Abuse Screening Scale (VASS), a 12-item self-report measure with four factors (Vulnerability, Dependence, Dejection, and Coercion). DESIGN AND METHODS: The sample consisted of 10,421 nationally representative Women's Health Australia study participants, aged 73-78, who completed the Time 2 postal survey in 1999. We tested validity of the VASS factor structure and whether baseline risk status independently predicted Time 2 attrition. RESULTS: Findings confirmed the VASS factor structure and construct validity. Four factors explained 51% of variance, and these factors were internally consistent. The Vulnerability and Coercion factors held the strongest face and construct validity for physical and psychological abuse. The Dependence and Dejection factors were valid and reliable and significantly predicted 3-year attrition after controlling for confounders. IMPLICATIONS: Further work is needed to determine sensitivity and specificity of VASS as a screening instrument for elder abuse. Qualitative research could examine specific experiences and contexts of vulnerable women.

Aged↗
PubMed2006

Coping with late-life challenges: Development and validation of the care-receiver efficacy scale.

PURPOSE: Measures are lacking that address the challenges that people think they face in their roles as elderly care receivers. However, the development of a sense of efficacy in this role by mentally competent care receivers is critical to successful partnerships between caregivers and care receivers. The purpose of this article is to report the development and psychometric analysis of the Care-Receiver Efficacy Scale (CRES). DESIGN AND METHODS: Content validity, internal consistency reliability, factor structure, and convergent validity were assessed through a pilot study, expert review, and field administration with 177 participants. RESULTS: Results suggest that the CRES comprises five subscales, with strong reliability evidenced for three subscales but marginal reliability for the remaining two. Strong support was found for content validity from expert review and moderate support from the relationship between empirical and expert judgment of item location. Support for validity also was found from correlation with the Geriatric Depression Scale-Short Form and the Philadelphia Geriatric Center Morale Scale. IMPLICATIONS: The CRES may be useful as an outcome measure for psycho-socio-behavioral interventions aimed at increasing the capacity of care receivers to direct and improve their own care. Future measure revision and validation are important to optimize its utility.

Adaptation, Psychological↗
PubMed1997

[Rosai-Dorfman lymphadenopathy, a rare reactive lymphoproliferative disease. How valid are ultrasound morphologic criteria in lymph node involvement?].

AIM: The established criteria for benignity or malignancy of lymph nodes when evaluated with B-mode ultrasound can be divided into quantitative measures (size, quantity, contour and density) and qualitative parameters (configuration and structure). The validity of these criteria is controversial. METHODS: Two cases of sinus histiocytosis with massive lymphadenopathy (SHML) are presented; this is a rare benign reactive disorder in which massive enlargement of cervical lymph nodes often occurs. These enlarged nodes offer a chance to demonstrate and discuss the validity of the sonomorphological criteria. RESULTS: The enlarged lymph nodes in SHML fulfill most of the criteria for malignancy. The same results are meet in other disorders with prominent but benign lymphadenopathy. CONCLUSION: The current ultrasonic criteria to determine benignity/malignancy in lymph nodes most likely simply indicate a large number of enlarged nodes. Pathologic diagnosis remains the gold standard.

Child↗