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PubMed1997

Novel 99mTc aminobisthiolato/monothiolato "3 + 1" mixed ligand complexes: structure-activity relationships and preliminary in vivo validation as brain blood flow imaging agents.

A series of neutral, lipophilic 99mTc mixed-ligand complexes of the general formula 99mTcOL1L2, where L1H2 is an N-substituted bis-(2-mercaptoethyl)amine, [X-CH2CH2N(CH2CH2SH)2], [SNS], and L2H is a monodentate thiol (RSH), [S], has been synthesized and evaluated in rodents for potential use in brain blood flow imaging. The complexes were prepared by ligand exchange reaction using 99mTc(V)O-glucoheptonate as precursor and equimolar quantities of the two ligands. In all cases the syn isomer was formed in a high yield, whereas the anti isomer was not always present. The formation of two isomeric complexes-syn and anti-was expected, since the N-substituent (X-CH2CH2N) can assume syn or anti configuration with respect to the 99mTcO3+ core during complexation. One anti and all syn isomers were isolated by HPLC. Their identity was confirmed by comparative HPLC studies with the analogous 99Tc complexes of established structure. In vivo distribution, in particular brain uptake and retention, greatly depended on the type of either tridentate (L1H2) or monodentate (L2H) ligand. All 99mTc complexes showed significant brain uptake in mice (0.78-4.35% injected dose per organ at 5 min postinjection). This initial uptake remained nearly constant for at least 30 min for most of the complexes. Structure-activity relationships of novel 99mTc(V)O SNS/S complexes in mice are reported and discussed. Selected complexes were further studied in rats. High brain uptake, comparable to that of 99mTc-d,l-HMPAO, and sufficient retention 60 min postinjection were provided with complex 18 [X = (C2H5)2N and R = p-CH3OC6H4CH2].

Animals↗
PubMed2001

Psychometric properties of the Temperament and Character Inventory (TCI) questionnaire in a Spanish psychiatric population.

OBJECTIVE: The psychometric properties of the Spanish version of Cloninger's Temperament and Character Inventory (TCI) were examined in a psychiatric population. METHOD: Internal consistency, factor structure and concurrent validity were studied in a sample of 416 psychiatric patients. RESULTS: A moderate to high internal consistency for all personality dimensions was found, except for Persistence. A confirmatory factor analysis of the TCI performed at the subscale level revealed an uncertain factor structure. However, when analysed separately, both the 11 temperament subscales (plus Persistence) and the 13 character subscales shaped four and three factors, respectively, in agreement with the biosocial model of personality. Finally, concurrent validity analyses were conducted using EPQ, SPSR and SSS questionnaires showing results consistent with theory. CONCLUSION: The Spanish version of the TCI is a reliable and valid instrument, although the Persistence dimension might require further revision.

Adult↗
PubMed1999

Protein secondary structure prediction based on position-specific scoring matrices.

A two-stage neural network has been used to predict protein secondary structure based on the position specific scoring matrices generated by PSI-BLAST. Despite the simplicity and convenience of the approach used, the results are found to be superior to those produced by other methods, including the popular PHD method according to our own benchmarking results and the results from the recent Critical Assessment of Techniques for Protein Structure Prediction experiment (CASP3), where the method was evaluated by stringent blind testing. Using a new testing set based on a set of 187 unique folds, and three-way cross-validation based on structural similarity criteria rather than sequence similarity criteria used previously (no similar folds were present in both the testing and training sets) the method presented here (PSIPRED) achieved an average Q3 score of between 76.5% to 78.3% depending on the precise definition of observed secondary structure used, which is the highest published score for any method to date. Given the success of the method in CASP3, it is reasonable to be confident that the evaluation presented here gives a fair indication of the performance of the method in general.

Algorithms↗
PubMed2006

The SCREEN I (Seniors in the Community: Risk Evaluation for Eating and Nutrition) index adequately represents nutritional risk.

OBJECTIVE: Nutrition risk is a difficult and complex construct to define and measure. Exploratory factor analysis has been completed on SCREEN I, a nutrition risk screening index for community-living seniors. This analysis was completed to confirm this structure and further validate the index as a plausible measure of nutritional risk. STUDY DESIGN AND SETTING: As part of the Bringing Nutrition Screening to Seniors demonstration project, 1,218 seniors completed SCREEN I. Using structural equation modeling (Amos version 5 software), the original and alternative two-, three-, and four-factor structures were modeled and compared. RESULTS: The best-fitting model was a four-factor structure based on the original exploratory model. Unlike the original model, however, several SCREEN I items cross-loaded on more than one factor, demonstrating the complexity of the construct 'nutritional risk.' CONCLUSION: SCREEN I appears to represent adequately the construct 'nutritional risk' with four factors: Food Intake, Physiologic, Adaptation, and Functional. Further work should be conducted to further elucidate the complex nature of 'nutritional risk' by identifying indirect and direct relationships among the screen items and this construct.

Aged↗
PubMed2002

Structural analysis of synthetic peptide fragments from EmrE, a multidrug resistance protein, in a membrane-mimetic environment.

EmrE, a multidrug resistance protein from Escherichia coli, renders the bacterium resistant to a variety of cytotoxic drugs by active translocation out of the cell. The 110-residue sequence of EmrE limits the number of structural possibilities that can be envisioned for this membrane protein. Four helix bundle models have been considered [Yerushalmi, H., Lebendiker, M., and Schuldiner, S. (1996) J. Biol. Chem. 271, 31044-31048]. The validity of EmrE structural models has been probed experimentally by investigations on overlapping peptides (ranging in length from 19 to 27 residues), derived from the sequence of EmrE. The choice of peptides was made to provide sequences of two complete, predicted transmembrane helices (peptides H1 and H3) and two helix-loop-helix motifs (peptides A and B). Peptide (B) also corresponds to a putative hairpin in a speculative beta-barrel model, with the "Pro-Thr-Gly" segment forming a turn. Structure determination in SDS micelles using NMR indicates peptide H1 to be predominantly helical, with helix boundaries in the micellar environment corroborating predicted helical limits. Peptide A adopts a helix-loop-helix structure in SDS micelles, and peptide B was also largely helical in micellar environments. An analogue peptide, C, in which the central "Pro-Thr-Gly" was replaced by "(D)Pro-Gly" displays local turn conformation at the (D)Pro-Gly segment, but neither a continuous helical stretch nor beta-hairpin formation was observed. This study implies that the constraints of membrane and micellar environments largely direct the structure of transmembrane peptides and proteins and study of judiciously selected peptide fragments can prove useful in the structural elucidation of membrane proteins.

Antiporters↗
PubMed1980

[Hematomorphological differential diagnosis of small cell lymphoma. What is the atypical chronic lymphadenosis?].

More importance is being attached to haematologic cell morphology, particularly in the field of small-cell non-Hodgkin lymphomas. This shifting of diagnostical validity from the structural substrate to the cellular one can clearly be illustrated by the transition of classification according to Rappoport to that according to Lennert (Kiel-classification). Here minute cytomorphological criteria acquire a new validity by their significance in the microscopic cut preparation and in the electron-microscope as well as by their correlation to cell-immunological parameters. Thus, it is possible to make a differential diagnostics of the extending small-cell lymphomas from the blood picture. It enables an ensured morphological differentiation to be made for typical B-lymphadenosis, prolymphocytic leukaemia, T-cell lymphadenosis, lymphoplasmocytoid immunocytoma, centrocytoma, and hairy cell leukaemia. The relevance of this differentiation can be further identified by a consequent immunologic cell characterization.

Cytodiagnosis↗
PubMed2005

Developmental delay at 12 months in children born extremely preterm.

AIM: To evaluate the feasibility and validity of a structured telephone interview to assess the development of children born extremely preterm. METHODS: The parents of 88 children born with a gestational age below 28 wk admitted to the neonatal intensive care unit (NICU) at Rigshospitalet, Copenhagen, were interviewed by telephone when their child was 1 y of age, corrected for preterm birth. A fully structured questionnaire on psychomotor function was used (Revised Prescreening Developmental Questionnaire (R-PDQ)). The parents of 30 children born at term without complications were interviewed for comparison. The interview was conducted by NICU staff. To validate the R-PDQ, parents of 22 children in the preterm group and parents of 19 children in the reference group conducted an Ages and Stages Questionnaire (ASQ) when their children had reached the age of 3-3(1/2) y. RESULTS: The R-PDQ was easy to use by staff and well accepted by parents. The mean score in the preterm group was 14.9+/-3.9 vs 17.7+/-2.7 in the term group (p<0.001). Three children had developmental scores below-2 SD. The R-PDQ score was associated with the ASQ score 2 y later. CONCLUSION: A structured questionnaire administrated by telephone is an alternative and usable tool for assessing neurodevelopmental deficit in children born extremely preterm. The mean developmental delay in the preterm group compared to the term group (about-1 SD) was close to expectations.

Child, Preschool↗
PubMed2000

Measuring quality of life of Chinese cancer patients: A validation of the Chinese version of the Functional Assessment of Cancer Therapy-General (FACT-G) scale.

BACKGROUND: Few cancer specific quality-of-life (QoL) measures from the West have been translated for use with Chinese-speaking patients, and no substantial validation of these translations with adequately large cohorts has been published previously, to the authors' knowledge. The Functional Assessment of Cancer Therapy-General (FACT-G) is a well-validated QoL instrument that is specific to cancer patients. The scale was translated into Chinese and the psychometric properties of this translated scale (FACT-G [Ch]) were tested with a Chinese sample in Hong Kong, China. METHODS: A total of 1262 Chinese cancer patients were selected in 3 samples from 5 Hong Kong regional hospitals. Quantitative and qualitative data were used to assess the cultural equivalence, factor structure, reliability, and validity of the FACT-G (Ch). RESULTS: Focus group discussions indicated that the FACT-G was seen as covering QoL domains identified as important and relevant to Chinese cancer patients, though in some respects it was seen as having limited scope in this sample. Psychometrically, the factor structure of the FACT-G deviated from that of the original work. The FACT-G (Ch) had acceptable reliability (Cronbach alpha 0.85). The convergent validity of the FACT-G (Ch) with a generic QoL measure (WHOQOL-BREF[HK]) was 0.72 (P < 0.001), and divergent validity showed low correlations of less than 0.15 (P < 0.05) with non-QoL measures. CONCLUSIONS: Focus group data indicated that the FACT-G translation into Chinese was seen as a conceptually relevant and moderately sufficient QoL measure. Psychometrically, the instrument had acceptable properties, but conceptual differences from the original version were suggested. Although more work is needed to increase its adequacy, the translated scale has reasonable utility for use with Chinese populations in clinical settings.

Adult↗
PubMed1994

Residues responsible for distinct biological functions are characterized by different statistical features of sequential and spatial neighborhoods: a thermolysin example.

An investigation of the functional topography of thermolysin was carried out using frequency analysis of its primary and tertiary structures. The statistical validity of this approach was estimated for the enzyme active site, the substrate-binding pocket, the inter-domain interface and calcium-binding sites' predictions. We showed that frequency analysis of primary structure could be employed to predict the localization of contiguous parts of the inter-domain interface. The same approach appears to be unsuitable to a search for conformation-dependent enzyme active sites and substrate-binding pockets. In contrast, frequency analysis of the spatial neighborhood is not effective for predicting the inter-domain interface as distinct from the active site, substrate-binding pocket and calcium-binding sites. These differences should be taken into account when investigating and understanding protein structure-function relationships.

Amino Acid Sequence↗
PubMed1998

An anatomic study of the rat larynx: establishing the rat model for neuromuscular function.

The gross and microscopic anatomy of the rat larynx was studied with particular attention to myology and neuromuscular structures to further validate it as a model to evaluate morphologic and functional changes induced by botulinum injection. A laryngeal alar cartilage (LAIC), alar cricoarytenoid (ACA) muscle, and a superior cricoarytenoid muscle (SCA) were identified as anatomic structures not previously described. Two portions (medial and lateral) of the thyroarytenoid muscle (TA) were distinguished. The function of the ACA was suggested to be similar to the aryepiglottis muscle in humans and the function of the SCA was suggested to be similar to the human interarytenoid muscle. The predominant pattern of motor endplate (MEP) distribution in rat laryngeal muscles (posterior cricoarytenoid, lateral cricoarytenoid, cricothyroid, and SCA) was to have MEPs concentrated mostly at the midbelly of muscle where they were distributed throughout the cross-sectional area of the midbelly. The TA and ACA differed from this pattern. The lateral TA had MEPs concentrated at the anterior third of its belly and those of the medial TA were located at the midbelly. Motor endplates in the ACA were located mostly at the posterior portion of muscle. Muscle fiber-typing showed subtle differences between the intrinsic laryngeal muscles. Fast fibers were predominant in the rat laryngeal muscles. This study supports the expanded use of rats in studies of laryngeal neuromuscular function and disease in humans.

Animals↗
PubMed2005

The French Aging Males' Symptoms (AMS) scale: methodological review.

BACKGROUND: The AMS is an internationally used health-related quality of life (HRQoL) scale. The aim of this paper is to provide evidence that the French AMS scale measures HRQoL are as valid as other language versions. We also intend to show whether the application of AMS is really limited to aging males only or not. More generally, we like to demonstrate that the AMS scale is a relevant, validated, sensitive instrument to measure HRQoL and change of symptoms in France. METHODS: We performed a representative survey in France to get data AMS scale data. The French data were compared with existing data from other European countries. Only community-based data were used for this comparison. RESULTS AND DISCUSSION: Reliability (here consistency, Cronbach' s alpha) was found to be good and almost identical with other countries. VALIDITY: the internal structure of the AMS (factorial analysis) was sufficiently comparable with the comparison group of other countries in Europe to conclude that the scale really measures the same phenomenon. The sub-scores and total score correlations (Pearson) were high (r = 0.8-0.9) but only somewhat lower among the sub-scales (r = 0.5-0.7). This suggests that the domains are correlated. The comparison of the French AMS with the generic quality-of-life scale SF-12 showed a good correlation (Pearson r = 0.48-0.51) as reported from other countries. We observed also a good correlation between the AMS scale and the depression scale HAD (Pearson r = 0.62). The analysis of the AMS structure across age groups showed sufficient similarity to suggest that the AMS is also useful for younger age groups. CONCLUSION: The French AMS scale is a standardized HRQoL scale with good psychometric characteristics (reliability, validity) as shown for other international versions. We suggest that the AMS scale could be also used in age groups under 40 years to measure and compare HRQoL in males. Since the application of the AMS in younger age was not investigated before, confirmation in future studies is needed.

Adolescent↗
PubMed2003

Validity and reliability of the general well-being schedule with northern plains American Indians diagnosed with type 2 diabetes mellitus.

The General Well-being Schedule is a brief indicator of subjective feelings of psychological well-being and distress. It is easy to administer, reliable, and valid, although its validity with American Indians has not been established. This study then assessed reliability, validity, and factor structure for a sample of 88 diabetic American Indians, who sought care for diabetes at an Indian Health Service hospital. Cronbach alpha was .89. A factor analysis indicated four dimensions. Adequate concurrent and divergent validity were noted in association with scores on the Beck Depression Inventory-Second Edition, the depression scale on the Symptom Checklist-90-Revised, and Family-Adaptation, Partnership, Growth, Affection, & Resolve. These results suggest that the General Well-being Schedule is a reliable and valid measure of general well-being for this population of American Indians.

Adult↗
PubMed1999

Evaluation of a novel molecular vibration-based descriptor (EVA) for QSAR studies: 2. Model validation using a benchmark steroid dataset.

The EVA molecular descriptor derived from calculated molecular vibrational frequencies is validated for use in QSAR studies. EVA provides a conformationally sensitive but, unlike 3D-QSAR methods such as CoMFA, superposition-free descriptor that has been shown to perform well with a wide range of datasets and biological endpoints. A detailed study is made using a benchmark steroid dataset with a training/test set division of structures. Intensive statistical validation tests are undertaken including various forms of crossvalidation and repeated random permutation testing. Latent variable score plots show that the distribution of structures in reduced dimensional space can be rationalized in terms of activity classes and that EVA is sensitive to structural inconsistencies. Together, the findings indicate that EVA is a statistically robust means of detecting structure-activity correlations with performance entirely comparable to that of analogous CoMFAs. The EVA descriptor is shown to be conformationally sensitive and as such can be considered to be a 3D descriptor but with the advantage over CoMFA that structural superposition is not required. EVA has the property that in certain situations the conformational sensitivity can be altered through the appropriate choice of the EVA sigma parameter.

Models, Molecular↗
PubMed1997

Homology modeling using simulated annealing of restrained molecular dynamics and conformational search calculations with CONGEN: application in predicting the three-dimensional structure of murine homeodomain Msx-1.

We have developed an automatic approach for homology modeling using restrained molecular dynamics and simulated annealing procedures, together with conformational search algorithms available in the molecular mechanics program CONGEN (Bruccoleri RE, Karplus M, 1987, Biopolymers 26:137-168). The accuracy of the method is validated by "predicting" structures of two homeodomain proteins with known three-dimensional structures, and then applied to predict the three-dimensional structure of the homeodomain of the murine Msx-1 transcription factor. Regions of the unknown protein structure that are highly homologous to the known template structure are constrained by "homology distance constraints," whereas the conformations of nonhomologous regions of the unknown protein are defined only by the potential energy function. A full energy function (excluding explicit solvent) is employed to ensure that the calculated structures have good conformational energies and are physically reasonable. As in NMR structure determinations, information on the consistency of the structure prediction is obtained by superposition of the resulting family of protein structures. In this paper, our homology modeling algorithm is described and compared with related homology modeling methods using spatial constraints derived from the structures of homologous proteins. The software is then used to predict the DNA-bound structures of three homeodomain proteins from the X-ray crystal structure of the engrailed homeodomain protein (Kissinger CR et al., 1990, Cell 63:579-590). The resulting backbone and side-chain conformations of the modeled yeast Mat alpha 2 and D. melanogaster Antennapedia homeodomains are excellent matches to the corresponding published X-ray crystal (Wolberger C et al., 1991, Cell 67:517-528) and NMR (Billeter M et al., 1993, J Mol Biol 234:1084-1097) structures, respectively. Examination of these structures of Msx-1 reveals a network of highly conserved surface salt bridges that are proposed to play a role in regulating protein-protein interactions of homeodomains in transcription complexes.

Algorithms↗
PubMed2000

Standardization of the Hare Psychopathy Checklist-Revised in a Spanish prison sample.

This investigation examined the reliability, validity, and factor structure of the Hare Psychopathy Checklist-Revised (PCL-R) in male adult Spanish prison populations (n = 117). The interrater reliability and internal consistency coefficients were high, and similar to those obtained in other countries. This data provides support for the homogeneity and unidimensionality of the psychopathy construct in Spanish male prison samples. The analysis of factor structure also replicated the two factor solution of previous studies. The two factors showed different patterns of intercorrelations with several self-report measures of personality, demographic, and criminal history variables, which confirmed the construct validity of PCL-R. The results confirm the psychometric properties of the PCL-R as a measure of psychopathy in Spanish male inmates, and suggest that psychopathy is a construct also observed in Southern European countries.

Adult↗
PubMed2000

Validation of selected donor-screening questions: structure, content, and comprehension.

BACKGROUND: Donor questioning is an integral component of blood safety, designed to identify and interdict donors considered to be at elevated risk of transfusion-transmissible infection. Questions are frequently added to this screening procedure, but they are rarely evaluated for comprehension. STUDY DESIGN AND METHODS: Seven American Red Cross blood donor history questions were selected for evaluation. Focus groups were conducted using individuals from high school/college, church, business, and other sources, who had never donated blood. Both sexes and various age and racial groups were represented. The donation process and regulatory requirements or guidelines were explained. Participants were asked to consider 1) content, 2) clarity 3) likelihood of asking for more information, 4) suggestions for improvement, and 5) how a need for clarifying information would best be met. RESULTS: Constructive, helpful, and consistent comments obtained might be utilized in revising questions. CONCLUSION: Focus group discussions can be useful in providing guidance for developing screening questions that can be easily understood.

Adult↗
PubMed2005

A flexible docking procedure for the exploration of peptide binding selectivity to known structures and homology models of PDZ domains.

PDZ domains are important scaffolding modules that typically bind to the C-termini of their interaction partners. Several structures of such complexes have been solved, revealing a conserved binding site in the PDZ domain and an extended conformation of the bound peptide. A compendium of information regarding PDZ complexes demonstrates that dissimilar C-terminal peptides bind to the same PDZ domain, and different PDZ domains can bind the same peptides. A detailed understanding of the PDZ-peptide recognition is needed to elucidate this complexity. To this end, we have designed a family of docking protocols for PDZ domains (termed PDZ-DocScheme) that is based on simulated annealing molecular dynamics and rotamer optimization, and is applicable to the docking of long peptides (20-40 rotatable bonds) to both known PDZ structures and to the more complicated problem of homology models of these domains. The resulting protocol reproduces the structures of PDZ complexes with peptides 4-8 amino acids long within 1-2 A from the experimental structure when the docking is performed to the original structure. If the structure of the target PDZ domain is an apo structure or a homology model, the docking protocol yields structures within 3 A in 9 out of 12 test cases. The automated docking procedure PDZ-DocScheme can serve in the generation of a structural context for validation of PDZ domain specificity from mutagenesis and ligand binding data.

Models, Molecular↗
PubMed2006

Distance measurements reveal a common topology of prokaryotic voltage-gated ion channels in the lipid bilayer.

Voltage-dependent ion channels are fundamental to the physiology of excitable cells because they underlie the generation and propagation of the action potential and excitation-contraction coupling. To understand how ion channels work, it is important to determine their structures in different conformations in a membrane environment. The validity of the crystal structure for the prokaryotic K(+) channel, K(V)AP, has been questioned based on discrepancies with biophysical data from functional eukaryotic channels, underlining the need for independent structural data under native conditions. We investigated the structural organization of two prokaryotic voltage-gated channels, NaChBac and K(V)AP, in liposomes by using luminescence resonance energy transfer. We describe here a transmembrane packing representation of the voltage sensor and pore domains of the prokaryotic Na channel, NaChBac. We find that NaChBac and K(V)AP share a common arrangement in which the structures of the Na and K selective pores and voltage-sensor domains are conserved. The packing arrangement of the voltage-sensing region as determined by luminescence resonance energy transfer differs significantly from that of the K(V)AP crystal structure, but resembles that of the eukaryotic K(V)1.2 crystal structure. However, the voltage-sensor domain in prokaryotic channels is closer to the pore domain than in the K(V)1.2 structure. Our results indicate that prokaryotic and eukaryotic channels that share similar functional properties have similar helix arrangements, with differences arising likely from the later introduction of additional structural elements.

Bacterial Proteins↗