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PubMed1995

Body image, body dysphoria, and dietary restraint: factor structure in nonclinical subjects.

The principal aim of this study was to examine the factor structure of several assessment methods used to measure dietary restraint, body dissatisfaction, and body image. Factor analysis was employed to identify and confirm the primary constructs measured by these assessment methods. A total of 206 undergraduate women were recruited as subjects. This sample was divided into two subsets of 100 and 106 subjects. On the first subset, principle components analysis identified three factors: body dysphoria, dietary restraint, and body image. With the second subset of subjects, confirmatory factor analysis cross-validated this factor structure. A two factor solution, body dysphoria and dietary restraint, was identified and confirmed when the body image measure was converted to a self-minus-ideal discrepancy score. These findings are discussed in relation to the definition of control groups to be used in studies of anorexia and bulimia nervosa. Guidelines for the selection of measures for each of the three factors also are presented.

Adult↗
PubMed1986

Concurrent and predictive validity of a self-reported measure of medication adherence.

Adherence to the medical regimen continues to rank as a major clinical problem in the management of patients with essential hypertension, as in other conditions treated with drugs and life-style modification. This article reviews the psychometric properties and tests the concurrent and predictive validity of a structured four-item self-reported adherence measure (alpha reliability = 0.61), which can be easily integrated into the medical visit. Items in the scale address barriers to medication-taking and permit the health care provider to reinforce positive adherence behaviors. Data on patient adherence to the medical regimen were collected at the end of a formalized 18-month educational program. Blood pressure measurements were recorded throughout a 3-year follow-up period. Results showed the scale to demonstrate both concurrent and predictive validity with regard to blood pressure control at 2 years and 5 years, respectively. Seventy-five percent of the patients who scored high on the four-item scale at year 2 had their blood pressure under adequate control at year 5, compared with 47% under control at year 5 for those patients scoring low (P less than 0.01).

Humans↗
PubMed1992

MD simulation of subtilisin BPN' in a crystal environment.

In this paper we present a molecular dynamics (MD) simulation of subtilisin BPN' in a crystalline environment containing four protein molecules and solvent. Conformational and dynamic properties of the molecules are compared with each other and with respect to the X-ray structure to test the validity of the force field. The agreement between simulated and experimental structure using the GROMOS force field is better than that obtained in the literature using other force fields for protein crystals. The overall shape of the molecule is well preserved, as is the conformation of alpha-helices and beta-strands. Structural differences are mainly found in loop regions. Solvent networks found in the X-ray structure were reproduced by the simulation, which was unbiased with respect to the crystalline hydration structure. These networks seem to play an important role in the stability of the protein; evidence of this is found in the structure of the active site. The weak ion binding site in the X-ray structure of subtilisin BPN' is occupied by a monovalent ion. When a calcium ion is placed in the initial structure, three peptide ligands are replaced by 5 water ligands, whereas a potassium ion retains (in part) its original ligands. Existing force fields yield a reliable method to probe local structure and short-time dynamics of proteins, providing an accuracy of about 0.1 nm.

Computer Simulation↗
PubMed1991

Three-dimensional structure of murine anti-p-azophenylarsonate Fab 36-71. 2. Structural basis of hapten binding and idiotypy.

Comparison between the structures and solvent-accessible surfaces of the antigen-binding fragments of two murine anti-p-azophenylarsonate monoclonal antibodies, one bearing a major cross-reactive idiotype of A/J strain mice (36-71) and one lacking the idiotype (R19.9; Lascombe et al., 1989), highlight the structural basis for the determination of hapten affinity and idiotypy. Since the sequence of R 19.9 is identical with the germline-encoded sequence at 16 positions in both heavy-chain and light-chain variable regions where somatic mutations and junctional differences have occurred to produce the 36-71 sequence, the structure of R 19.9 can be used to model the structure of the germline-encoded antibody (36-65) in the regions around these sites. These 16 sequence differences exclude the third heavy-chain complementarity-determining region because R 19.9 utilizes a D gene segment not associated with the predominant idiotype, which is 4 residues longer than the canonical D gene segment utilized in the sequences of 36-71 and 36-65. This difference between the structures of R 19.9 and 36-71 does not affect the validity of using the structure of R 19.9 to model the structure of 36-65 since the third heavy-chain complementarity-determining region is highly solvent-exposed in both 36-71 and R 19.9, and does not interact with any of these 16 sites. Comparing the structures of 36-71 and R 19.9 suggests that only three of the differences in the heavy-chain sequences, and three of the differences in the light-chain sequences of 36-71 and 36-65, increase the affinity for hapten.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1991

Predicting common foldings of homologous RNAs.

A new approach is proposed for determining common RNA secondary structures within a set of homologous RNAs. The approach is a combination of phylogenetic and thermodynamic methods which is based on the prediction of optimal and suboptimal secondary structures, topological similarity searches and phylogenetic comparative analysis. The optimal and suboptimal RNA secondary structures are predicted by energy minimization. Structural comparison of the predicted RNA secondary structures is used to find conserved structures that are topologically similar in all these homologous RNAs. The validity of the conserved structural elements found is then checked by phylogenetic comparison of the sequences. This procedure is used to predict common structures of ribonuclease P (RNAase P) RNAs.

Algorithms↗
PubMed1989

The reliability of mandibular radiographic superimposition.

Using tracings from thirty pairs of serial cephalometric radiographs, the reliability of three outlines, commonly used for mandibular superimposition, was investigated. There were sizeable errors associated with all three groups, but tracings involving Björk's mandibular structures were found to be the least reliable. Despite the greater validity of the Björk structures for assessment of growth changes, in certain cases the use of the mandibular outline may be of greater value for the superimposition of tracings, especially when the time interval between the radiographs is short, or the patient has passed maturity and the growth rate has declined to a negligible level.

Adolescent↗
PubMed1995

The politics of nursing: a case study--clinical grading.

This paper is a study of the clinical grading policy for nurses in the United Kingdom and the extent to which the participating groups in the policy development process realized their objectives. The study is based on the literature available at the time of the research and the results of structured interviews with a range of individuals involved in the policy process. The results expose the cleavages between the different representative groups on the staff side. They also shed light on the differing power bases of the groups involved. In particular, they expose the weakness of nursing as a professional pressure group and the strength of the state and its agents in determining the outcomes of policy in the public arena. It is suggested that this weakness vis-à-vis the state is responsible for the failure of nurses to achieve a reward system which recognizes the value of clinical nursing expertise, and that the 'clinical grading' system, in practice, is having the opposite effect. The policy is explored from its origins, its acceptance on to the political agenda, its negotiation and agreement, its contentious implementation, the final outcomes, and its failure to establish a valid 'clinical' pay structure.

Clinical Competence↗
PubMed1995

Reliability, validity and factorial dimensions of the Interactive Observation Scale for Psychiatric Inpatients.

The Interactive Observation Scale for Psychiatric Inpatients (IOSPI) is characterized by the necessity of interaction between the rater and the patient during the evaluation process. The reliability, validity and factor structure of the IOSPI were evaluated by using a total of 186 sets of ratings accomplished by 2 nursing aides on 34 adult psychiatric inpatients submitted to weekly evaluations during the 3 first weeks of hospitalization. The patients were observed by the 2 nursing aides simultaneously during the morning shift (5 h). In the afternoon of the same day, they were interviewed by two psychiatrists who filled in separately the Brief Psychiatric Rating Scale (BPRS). Factor analysis of the 16 IOSPI items revealed 5 distinct clusters of items, which represented higher-order constructs of social interest, psychomotor agitation, psychoticism, neatness and irritability. It was found that the IOSPI has significant interrater reliability, estimated by an intraclass correlation coefficient of total score and factor score. The total scores of the IOSPI showed a significant correlation with the total scores of the BPRS, meeting the criteria of concurrent validity. The criteria of predictive validity were also met, since the patients who could be discharged presented IOSPI scores significantly lower than the patients who could not be discharged. In conclusion, the IOSPI met the requirements of an evaluation scale and can stimulate therapeutic attitudes of the nursing staff by its characteristics of interactive observation.

Factor Analysis, Statistical↗
PubMed1991

Morphometrical analysis of structural abnormality of tubular tumors of the stomach with image processing.

Four indices, index of tubular density, index of dispersion of tubular size, degree of complexity of tubular shape and frequency of complex-shaped tubuli, were defined to quantify the structural abnormalities of gastric tumors in morphometrical analysis by image processing. The values of each index corresponded well with the degree of each structural abnormality found pathologically. These indices were considered to be valid for representing their respective structural factors. There were significant differences among the mean values of the scores calculated by a formula using all 4 indices of benign tubular adenoma, borderline lesion and well-differentiated type tubular adenocarcinoma (P less than 0.05). Therefore, the discriminant formula was considered to be valid for integrating these indices and for representing structural abnormality of gastric tubular tumors.

Adenocarcinoma↗
PubMed1984

Psychological Screening Inventory: a comprehensive review.

The Psychological Screening Inventory is a relatively brief, easy to administer and score screening instrument that was designed for use by a wide range of professional mental health workers. A comprehensive review of the empirical literature suggests moderate reliability, generally stable factor structure, and adequate validity, particularly for use with college undergraduates, with reformatory and prison inmates, and with psychiatric outpatients.

Humans↗
PubMed1984

Criteria for the tracer kinetic measurement of cerebral protein synthesis in humans with positron emission tomography.

The principles and initial results of the use of PET to measure the local cerebral metabolic rate for protein synthesis ( lCRPS ) in humans are described. The labeling of leucine, phenylalanine, and methionine in the carboxyl position provides a strategy (selective position labeling) for discriminating between the incorporation of these amino acids into proteins and metabolic oxidation. In metabolic oxidation the label is removed from tissue through decarboxylation. The resulting labeled carbon dioxide is diluted by the tissue carbon dioxide pool, cleared from cerebral tissue by blood flow, and subsequently ventilated by the lungs. This approach also provides a plasma input function that is free of other labeled amino acids produced through systemic reactions, such as those that occur for methionine labeled in the methyl group. The measured lCRPS is in good agreement with values determined by Smith and Sokoloff by autoradiographic and biochemical assay techniques, as are the measured kinetic rate constants of bidirectional transport, incorporation into proteins, and metabolism, as determined in monkeys and humans using L-leucine labeled with carbon-11 in position 1 (L-[1-11C]leucine) with PET. The tissue leucine precursor pool exhibits a rapid turnover rate (1.5 to 2 minutes), while the metabolic pathway has a half-time (about 18 minutes) that is close to the radioactive half-life of carbon-11. The dietary state was found to affect the branching ratio of lCRPS /metabolism, with a fasted value of 0.4 and carbohydrate feed values ranging up to 1.7. The principle of the method appears sound, and a first-order model provides good fits to data, but much more work is required to determine and validate the model structure and to optimize the study conditions and estimation criteria.

Amino Acids↗
PubMed1991

Comparative modeling of mammalian aspartate transcarbamylase.

Mammalian aspartate transcarbamylase (ATCase) is part of a 243 kDa multidomain polypeptide, called CAD, that catalyzes the first three steps in de novo pyrimidine biosynthesis. The structural organization of the mammalian enzyme is very different from E. coli ATCase, a dodecameric, monofunctional molecule comprised of six copies of separate catalytic and regulatory chains. Nevertheless, sequence similarities and other properties suggested that the mammalian ATCase domain and the E. coli ATCase catalytic chain have the same tertiary fold. A model of mammalian ATCase was built using the X-ray coordinates of the E. coli catalytic chain as a tertiary template. Five small insertions and deletions could be readily accommodated in the model structure. Following energy minimization the RMS difference in the alpha carbon positions of the mammalian and bacterial proteins was 0.93 A. A comparison of the hydrophobic energies, surface accessibility index, and the distribution of hydrophilic and hydrophobic residues of the CAD ATCase structure with correctly and incorrectly folded proteins and with several X-ray structures supported the validity of the model. The mammalian ATCase domain associates to form a compact globular trimer, a prerequisite for catalysis since the active site is comprised of residues from adjacent subunits. Interactions between the clearly defined aspartate and carbamyl phosphate subdomains of the monomer were largely preserved while there was appreciable remodeling of the trimeric interfaces. Several clusters of basic residues are located on the upper surface of the domain which account in part for the elevated isoelectric point (pI = 9.4) and may represent contact regions with other more acidic domains within the chimeric polypeptide. A long interdomain linker connects the monomer at its upper surface to the remainder of the polypeptide. The configuration of active site residues is virtually identical in the mammalian and bacterial enzymes. While the CAD ATCase domain can undergo the local conformational changes that accompany catalysis in the E. coli enzyme, the high activity, closed conformation is probably more stable in the mammalian enzyme.

Amino Acid Sequence↗
PubMed1987

The numerical approach to classification: a medical application to develop a typology for facial pain.

Applications of numerical taxonomy in medicine are relatively rare. We describe an application in which a new typology is developed for the classification of pain distribution in patients with temporomandibular pain dysfunction syndrome. The methodology of the numerical approach is presented and key issues are highlighted, especially relating to validation of taxonomic structure. From the dendrogram obtained by Ward's hierarchical method, five pain groups are distinguished which relate systematically to anatomy and are clinically meaningful. Cluster structure is subjected to a battery of reproducibility tests and is found to be broadly reproducible for different algorithms and sub-samples of subjects. Finally, the new typology is shown to have heuristic value in providing fresh insight into the nature of a complex syndrome.

Algorithms↗
PubMed1990

Estimating benefits of screening from observational cohort studies.

Analysis and interpretation of observational studies of screening effectiveness is difficult because several biases threaten validity, including the structural healthy screenee bias, length bias, and effects of lead time. Although methods for the analysis of observational studies of screening effectiveness have been proposed, most have limitations such as incomplete control of length bias, or a heavy reliance on distributional assumptions. In this report we present a method for the analysis of observational cohort studies of screening effectiveness. Although developed independently and formulated specifically for estimating benefits of screening, our approach is implied by a more general approach developed previously by Robins. Our approach, in contrast to other available methods, avoids the healthy screenee bias, and length and lead time bias, and allows an empirical approach to analysis that need not depend highly on distributional assumptions. We illustrate application of the approach with analysis of published data from a study of breast cancer screening.

Bias↗
PubMed1979

Classification of human placental villi. II. Morphometry.

Villi of placental tissue obtained from normal term placentae at Caesarean section were embedded in Epon. Semithin sections were subjected to morphometry. The villi were first grouped according to the modified classification proposed in the foregoing paper. The parameters examined include villous numbers, size, vascularity, volume of trophoblast and connective tissue. The measured values differ markedly from those obtained from paraffin sections. Statistically significant differences exist between the different types of villi in various parameters, providing further evidence supporting the validity of the structural classification suggested.

Cell Membrane↗
PubMed1980

Identification of a carbohydrate receptor recognized by uropathogenic Escherichia coli.

Earlier investigations have shown that pyelonephritic Escherichia coli specifically recognize and bind to carbohydrate structures correlated to the P blood group antigens. These findings are confirmed and extended in this study. Twenty-two of 23 nonselected E. coli strains from children with acute febrile pyelonephritis failed to agglutinate human erythrocytes lacking the antigens within the P blood group system. Only one of 32 faecal isolates exhibited this specific agglutinating property. The new informatin in this paper is that P2k erythrocytes, containing only the Pk antigen, were agglutinated to the same extent by pyelonephritic E. coli strains, giving further support to the proposal that the Pk glycosphingolipid is related to the receptor for pyelonephritic E. coli. In addition, the importance of the oligosaccharide moiety of the Pk glycosphingolipid for the binding of E. coli was further investigated. The synthesized disaccharide alpha-D-Galp-(1-4)-beta-D-Galp-1-O-0-NO2 inhibited the agglutination of human erythrocytes caused by two pyelonephritic E. coli strains at concentrations of less than 1 mM. Hence, the minimal receptor structure recognized by these E. coli strains appears to be the alpha-D-Galp-(1-4)-beta-D-Galp structure. How generally valid this observation may be needs further investigation. The findings may open new possibilities for diagnosis and treatment of urinary tract infection.

Animals↗
PubMed1984

Morphological changes in rat hepatocytes in primary culture induced by Misonidazole, desmethylmisonidazole and Ro 03-8799.

Isolated rat hepatocytes in early primary culture were incubated in the presence of three substituted nitroimidazoles currently of clinical interest as tumour radiosensitisers. The effects of 3h treatments with Misonidazole (MISO), Desmethylmisonidazole (DESMISO) and the basic compound Ro 03-8799 were monitored both directly from treatment and following a 24h 'recovery' period. Morphological changes were observed by SEM and TEM and included effects on the plasma membrane and the nucleus. The plasma membrane of DESMISO and 03-8799 treated cells was characterised by blebbed regions not present in control cultures, and considered indicative of an early toxic insult. Blebs were most evident in 03-8799 treated hepatocytes where they often contained coils of endoplasmic reticulum within the ground plasma. Blebbed areas were less evident 24h after the removal of the drugs from surviving cells. An increased aggregation of peripherally located heterochromatin within the nucleus was the other main morphological alteration induced by nitroimidazole treatment. This was again more prevalent in 03-8799 and DESMISO exposures; and particularly in cells demonstrating membrane damage. Parallel viability studies indicated an efficacy of the nitroimidazole towards rat liver parenchymal cells in primary culture of Ro 03-8799 greater than DESMISO greater than MISO. This fitted the order predicted from the morphological findings and from previously published clinical data. The validity of monitoring structural parameters as a means of initially indicating lesion sites following drug treatments in the hepatocyte cytotoxic screening model is considered.

Animals↗
PubMed1986

An empirical typology of problem drinkers from the Michigan Alcoholism Screening Test.

In a program of treatment for persons convicted of driving while intoxicated, data from 504 male participants were collected and analyzed to identify groups homogeneous with respect to symptoms and consequences of problem drinking as indicated on the Michigan Alcoholism Screening Test (MAST). Cluster analysis of MAST responses yielded 7 such groups, differing in level and pattern of alcohol-related problems. This classification was shown: (a) to be homogeneous and reliable; (b) to discriminate effectively within several sets of external criteria--specifically, scales and profiles from the Minnesota Multiphasic Personality Inventory (MMPI) and clinical ratings of reasons for drinking and of participation and outcome from treatment; and (c) to predict alcoholism criteria more powerfully than dimensional use of the MAST. Categorical representation of alcoholism from its psychosocial symptoms was shown to be a valid and valuable structural approach.

Adult↗