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PubMed2004

A meta-analysis of controlled studies comparing major malformation rates in IVF and ICSI infants with naturally conceived children.

PURPOSE: To estimate the risk of major malformations in IVF and ICSI infants. METHODS: Forty-four studies published in English since 1990 where the major malformation rate for IVF or ICSI cases was compared to an appropriate control group were reviewed. Nineteen studies met all selection criteria. In addition, a quality score was developed to assess each study based on sample size, timing of diagnosis, appropriateness of control group and other factors. RESULTS: In 19 studies, the major malformation rates ranged from 0-9.5% for IVF; 1.1-9.7 for ICSI; and 0-6.9% in the control groups. When ICSI was compared to IVF, and multiple births compared to singleton, there were no statistically significant differences. When data from 16 studies involving 28,524 IVF infants and 2,520,988 spontaneously conceived controls and 7 studies involving 7234 ICSI infants and 978,078 controls were pooled, we found an overall odds ratio for the 19 studies of 1.29 (95% CI 1.01-1.67). CONCLUSIONS: The overall odds ratio of 1.29 was statistically significant at the 5% level. These results may be useful for counseling ART patients and properly designing the consent forms used for ART procedures. It is not clear whether this risk is due to the procedures used in ART. We found that some of these studies have design flaws. All of them lacked an appropriate control group, i.e. infertile patients conceiving spontaneously. These flaws may create biases that would in almost all instances increase the risk of major malformations in the study group. Further research with better designed studies will likely result in a better estimate of the risk of major malformations associated with IVF and ICSI.

Congenital Abnormalities↗
PubMed2006

Trends in gambling studies research: quantifying, categorizing, and describing citations.

As opportunities to gamble have increased during the 20th century, so has gambling research. This study used new strategies, methods, and technology to examine citation trends and the growth of knowledge in the field of gambling studies. The sample included 2,246 citations that were published between 1903 and 2003. By using multiple keywords to classify each citation into distinct topic areas, this study yielded a more comprehensive analysis than was previously available. The results reveal that gambling-related research has grown at an exponential rate. The most prevalent topics explored within gambling studies citations have been pathology, risk-taking, decision-making and addiction. Between 1999 and 2003, studies addressing epidemiology, drug abuse, comorbidity and neuroscience have become increasingly prevalent. Based on these trends and their implications, this paper provides several recommendations for both future areas of inquiry within the field of gambling studies and better classification techniques for citations within all fields of psychology.

Abstracting and Indexing↗
PubMed2006

Prediction of sickness absence in patients with chronic low back pain: a systematic review.

OBJECTIVES: To provide evidence of predictors for sickness absence in patients with non-specific chronic low back pain (CLBP), distinguishing predictors aimed at the decision to report sick (absence threshold) and decision to return to work (return to work threshold). METHODS: Medical and psychological databases were searched, as well as citations from relevant reviews. In- and exclusion criteria were applied. Two reviewers assessed the methodological quality of the papers independently. RESULTS: Many different predictors were studied, and few factors were studied more than once. Consistent evidence was found for own expectations of recovery only as predictor for the decision to return to work. Patients with higher expectations had less sickness absence at the moment of follow-up measurement. As expected, different predictors were found aiming at the absence threshold or the return to work threshold. Furthermore, predictors varied also with the measurement instruments used, timing of follow-up measurements, and definition of outcomes. Until now, too few studies are available to overcome several potential sources of heterogeneity. CONCLUSIONS: No core set of predictors exists for sickness absence in general. The characteristics of the study including the decision to report sick or to return to work determined the influence of several predictors on sickness absence in patients with CLBP. Further research and use of a core set of measurements and uniform definitions are needed to predict sickness absence and return to work in patients with CLBP.

Absenteeism↗
PubMed1990

The real number of road traffic accident casualties in The Netherlands: a year-long survey.

Between August 1986 and July 1987 more than 24,000 households, containing nearly 67,000 persons, were surveyed by telephone about traffic injuries during the past three months. Expressed on an annual basis, approximately 430,000 people, or about 1 in 34 of the Dutch population, had suffered some sort of injury in a road accident. The road traffic morbidity was, therefore, 2,942 per 100,000 inhabitants. Of these, about 135,000 had to be treated in hospital (20,000 as inpatients). More than 100,000 did not need treatment. Cyclists formed by far the largest category of road user, but mopedists had the highest injury rate per kilometer travelled. 210,000 of these casualties fell within the definition for recording by the police. The police recorded only 49,748 traffic casualties, or about 25%, during the same period. The police data were not representative; the completeness declined according to severity of the injuries: inpatients, about 70%; outpatients 26%; extramural about 11%. Cyclists (11%), children (9%), and single vehicle accidents (5%) were very much underrepresented. The largest category of road user is cyclists, not car occupants as indicated by the police data. A number of recommendations are made for supplementing the police data and the existing hospital inpatient data. These include extending the Home Accident Recording System of outpatients and the General Practitioner Panel to include road accident victims. Together a representative sample of 95% of all those receiving medical treatment would thus be obtained.

Accidents, Traffic↗
PubMed1991

Protein secondary structure from Fourier transform infrared spectroscopy: a data base analysis.

An infrared (ir) method to determine the secondary structure of proteins in solution using the amide I region of the spectrum has been devised. The method is based on the circular dichroism (CD) matrix method for secondary structure analysis given by Compton and Johnson (L. A. Compton and W. C. Johnson, 1986, Anal. Biochem. 155, 155-167). The infrared data matrix was constructed from the normalized Fourier transform infrared spectra from 1700 to 1600 cm-1 of 17 commercially available proteins. The secondary structure matrix was constructed from the X-ray data of the seventeen proteins with secondary structure elements of helix, beta-sheet, beta-turn, and other (random). The CD and ir methods were compared by analyzing the proteins of the CD and ir databases as unknowns. Both methods produce similar results compared to structures obtained by X-ray crystallographic means with the CD slightly better for helix conformation, and the ir slightly better for beta-sheet. The relatively good ir analysis for concanavalin A and alpha-chymotrypsin indicate that the ir method is less affected by the presence of aromatic groups. The concentration of the protein and the cell path length need not be known for the ir analysis since the spectra can be normalized to the total ir intensity in the amide I region. The ir spectra for helix, beta-sheet, beta-turn, and other, as extracted from the data-base, agree with the literature band assignments. The ir data matrix and the inverse matrix necessary to analyze unknown proteins are presented.

Circular Dichroism↗
PubMed1992

A 1H NMR database computer program for the analysis of the primary structure of complex carbohydrates.

A 1H NMR database computer program has been developed to determine the primary structure of complex carbohydrates. The database contains carbohydrate structures, their corresponding 1H NMR data, and literature references. From an input list of chemical shift values, the program generates an output list of partially or completely matching carbohydrate structures. In order to facilitate the recognition of the matching part of the selected carbohydrate structures, these structures are displayed with the matching structural elements highlighted. This new 1H NMR database, together with the search program described, now provides a fast access to the published 1H NMR data of complex carbohydrates and furnishes easy links to carbohydrate structures. The performance of the program is demonstrated by the analysis of five carbohydrate fractions prepared from a pool of horse serum glycoproteins.

Carbohydrate Conformation↗
PubMed1991

Semantic networks of English.

Principles of lexical semantics developed in the course of building an on-line lexical database are discussed. The approach is relational rather than componential. The fundamental semantic relation is synonymy, which is required in order to define the lexicalized concepts that words can be used to express. Other semantic relations between these concepts are then described. No single set of semantic relations or organizational structure is adequate for the entire lexicon: nouns, adjectives, and verbs each have their own semantic relations and their own organization determined by the role they must play in the construction of linguistic messages.

Attention↗
PubMed1991

An integrated information system for the intervention and prevention of AIDS.

The epidemic of acquired immune deficiency syndrome (AIDS) and its causative agent, the human immunodeficiency virus (HIV), are serious and spreading. In response to the epidemic, a variety of intervention and prevention programs have been instituted. In such AIDS intervention and prevention (AIP) activities, the role played by information systems becomes more and more important. The applications of information systems technology in AIP mostly seem to fall within a spectrum of databases, decision support systems and expert systems. This paper describes the implementation of an information system in a regional AIDS intervention and prevention program. In this integrative information system, the database is integrated with both decision support systems and expert systems, and decision support systems are integrated with expert systems. The implementation results of the system present evidence of the usefulness of the system in AIDS intervention and prevention.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Database algorithm for generating protein backbone and side-chain co-ordinates from a C alpha trace application to model building and detection of co-ordinate errors.

The problem of constructing all-atom model co-ordinates of a protein from an outline of the polypeptide chain is encountered in protein structure determination by crystallography or nuclear magnetic resonance spectroscopy, in model building by homology and in protein design. Here, we present an automatic procedure for generating full protein co-ordinates (backbone and, optionally, side-chains) given the C alpha trace and amino acid sequence. To construct backbones, a protein structure database is first scanned for fragments that locally fit the chain trace according to distance criteria. A best path algorithm then sifts through these segments and selects an optimal path with minimal mismatch at fragment joints. In blind tests, using fully known protein structures, backbones (C alpha, C, N, O) can be reconstructed with a reliability of 0.4 to 0.6 A root-mean-square position deviation and not more than 0 to 5% peptide flips. This accuracy is sufficient to identify possible errors in protein co-ordinate sets. To construct full co-ordinates, side-chains are added from a library of frequently occurring rotamers using a simple and fast Monte Carlo procedure with simulated annealing. In tests on X-ray structures determined at better than 2.5 A resolution, the positions of side-chain atoms in the protein core (less than 20% relative accessibility) have an accuracy of 1.6 A (r.m.s. deviation) and 70% of chi 1 angles are within 30 degrees of the X-ray structure. The computer program MaxSprout is available on request.

Algorithms↗
PubMed1992

Predicting protein secondary structure content. A tandem neural network approach.

A priori knowledge of secondary structure content can be of great use in theoretical and experimental determination of protein structure. We present a method that uses two computer-simulated neural networks placed in "tandem" to predict the secondary structure content of water-soluble, globular proteins. The first of the two networks, NET1, predicts a protein's helix and strand content given information about the protein's amino acid composition, molecular weight and heme presence. Because NET1 contained more adjustable parameters (network weights) than learning examples, this network experienced problems with memorization, which is the inability to generalize onto new, never-seen-before examples. To overcome this problem, we designed a second network, NET2, which learned to determine when NET1 was in a state of generalization. Together, these two networks produce prediction errors as low as 5.0% and 5.6% for helix and strand content, respectively, on a set of protein crystal structures bearing little homology to those used in network training. A comparison between three other methods including a multiple linear regression analysis, a non-hidden-node network analysis and a secondary structure assignment analysis reveals that our tandem neural network scheme is, indeed, the best method for predicting secondary structure content. The results of our analysis suggest that the knowledge of sequence information is not necessary for highly accurate predictions of protein secondary structure content.

Databases, Bibliographic↗
PubMed1993

Estimation of the steady-state characteristics of the Hodgkin-Huxley model from voltage-clamp data.

In a companion paper in this issue we show that all the parameters and functions of the Hodgkin-Huxley (HH) model can be calculated in a unique and optimal manner from voltage-clamp peak current data when the steady-state activation (x infinite) and inactivation (z infinite) characteristics are known. Assuming that x infinite and z infinite can be adequately expressed by a Boltzmann equation with two parameters, the present paper describes an optimization procedure to estimate these parameters from peak current data without any constraint on the time constants of activation and inactivation. The required voltage-clamp data are the peak ionic current value (Ip) and its time of occurrence (tp), as provided by two complementary voltage-clamp protocols involving, in each case, a single fixed value of clamp potential. The performance of the procedure was very good with simulated medium- or high-resolution data as it was then possible to determine with confidence the degrees of the gating variables. The performance was also very good with low-resolution data, provided that the degrees of the gating variables were chosen correctly. Good results were also obtained in the presence of Gaussian noise. On the other hand, estimates of x infinite and z infinite based on normalization of peak current measurements always give uncertain results that are likely to be incorrect in a number of circumstances. It is concluded that the HH model can be a useful tool for the interpretation of voltage-clamp peak current data when a reasonable database is available.

Animals↗
PubMed1992

Simultaneous evaluation of genotoxicity data from different sources: a multivariate statistical approach.

A great deal of information on short-term mutagenicity assays presently exists, having been generated through individual as well as large comparative programs. The comparative programs have often examined the same tests, but with different sets of chemicals; this then gives rise to the problem of how to identify the information which is common to the different data bases, i.e., the general properties of the assays. This paper continues previous analyses of this subject, and describes a general approach by which different and heterogeneous data bases can be compared to each other. The results relative to 4 assays (Salmonella typhimurium gene mutation, mouse lymphoma L5178Y cell gene mutation, chromosomal aberrations in CHO cells, and SCEs in CHO cells) in 4 different data bases were studied. Factor analysis was used to model the different pieces of information. The analysis demonstrated a concordance between the indications of the U.S. National Toxicology Program and the International Program for the Evaluation of Short-Term Tests for Carcinogens, whereas the results of Gene-Tox and the International Program for Chemical Safety turned out to be biased, to different degrees, by their specific aims and characteristics. Moreover, the general properties--independent of the specific data bases--of the 4 assays were highlighted, and the similarities between the performances of the assays were given a quantitative measure.

Animals↗
PubMed1993

Comparison of the spectra of genetic damage in N4-hydroxycytidine-induced ad-3 mutations between nucleotide excision repair-proficient and -deficient heterokaryons of Neurospora crassa.

A comparison has been made of the mutagenic effects of N4-hydroxycytidine (HC) in the adenine-3 (ad-3) region of two-component heterokaryons of Neurospora crassa: nucleotide excision repair-proficient (uvs-2+/uvs-2+) heterokaryon 12 (H-12) and nucleotide excision repair-deficient (uvs-2/uvs-2) heterokaryon 59 (H-59). HC was found to produce mutations predominantly, if not exclusively, by AT to GC base-pair transitions in Escherichia coli strain K12 by Janion and Glickman (1980, Mutation Res., 72, 43-47) and Sledziewska-Gojska et al. (1992, Mutagenesis, 7, 41-46). The ad-3 forward-mutation, specific-locus assay system permits the recovery of ad-3A and/or ad-3B mutants resulting from gene/point mutation, multiple-locus mutation, and multilocus deletion mutation. Uvs-2, which is homokaryotic in H-59, results in a recovery of HC-induced ad-3 forward mutations at a frequency in H-59 that is comparable to that found in H-12. Genetic analysis of ad-3 mutants recovered from experiments with HC treatment demonstrates that predominantly gene/point mutations were found in both strains: 99.3% (540/544) in H-12, and 97.4% (531/545) in H-59. Genetic analysis of allelic complementation among the ad-3BR mutations demonstrated that HC induced the highest percentage of complementing mutants ever found with base analogs both in H-12 (99.7% [328/329]) and H-59 (91.2% [290/318]). As a result of these findings, the majority of HC-induced ad-3 mutations are postulated to have resulted from missense mutations. Thus, we conclude that the results in Neurospora are consistent with the observations in E. coli strain K-12, where HC induces predominantly AT to GC base-pair transitions.

Adenine↗
PubMed1991

Development of a predictive model for biodegradability based on BIODEG, the evaluated biodegradation data base.

A file of evaluated biodegradation data was used to develop a model for predicting aerobic biodegradability from chemical structure alone. Chemicals were initially divided into three groups: (i) chemicals that degrade rapidly under most environmental conditions without requiring acclimation; (ii) chemicals that degrade slowly or not at all; and (iii) chemicals that are biodegradable, but only after an acclimation period. Chemicals in the first two groups were then used to develop a model for classifying chemicals as rapidly or not rapidly biodegradable. The model is based on linear regression against 34 preselected substructures, and correctly classifies 92% (211 or 229) of the chemicals in the final training set.

Aerobiosis↗
PubMed1991

ASTER: an integration of the AQUIRE data base and the QSAR system for use in ecological risk assessments.

Ecological risk assessments are used by the US Environmental Protection Agency (US EPA) and other governmental agencies to assist in determining the probability and magnitude of deleterious effects of hazardous chemicals on plants and animals. These assessments are important steps in formulating regulatory decisions. The completion of an ecological risk assessment requires the gathering of ecotoxicological hazard and environmental exposure information. This information is evaluated in the risk characterization section to assist in making the final risk assessment. ASTER (ASsessment Tools for the Evaluation of Risk) was designed by the US EPA Environmental Research Laboratory-Duluth (ERL-D) to assist regulators in producing assessments. ASTER is an integration of the ACQUIRE (AQUatic toxicity Information REtrieval system) and QSAR (Quantitative Structure Activity Relationships) systems. ACQUIRE is a data base of aquatic toxicity tests and QSAR is comprised of a data base of measured physicochemical properties, and various QSAR models that estimate physicochemical and ecotoxicological endpoints. ASTER will be available to international governmental agencies through the US EPA National Computing Center.

Animals↗
PubMed1992

The ICOH and IUPAC international programme for establishing reference values of metals.

In cooperation with the ICOH Scientific Committee on the Toxicology of metals and IUPAC Commission on Toxicology, we have developed evaluation criteria for derivation of reference values for metal concentrations in human tissues and fluids. In a first attempt to illustrate how these criteria may be used, tentative reference values for mercury in human blood were derived. For persons who do not eat fish, a mean value of 10 mumol/1 (2 micrograms/1) was suggested. It was pointed out, however, that this value was based on information that did not meet the desired quality requirements, which, unfortunately were not met by any of the published reports.

Animals↗