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PubMed2005

Spermicide used alone for contraception.

BACKGROUND: Spermicides have been used as contraceptives for thousands of years. Despite this long use, only recently have studies examined the comparative efficacy and acceptability of these vaginal medications. Spermicides contain an active ingredient (most commonly nonoxynol-9) and a formulation used to disperse the product, such as foam or vaginal suppository. OBJECTIVES: This review examined all known randomized controlled trials of a spermicide used alone for contraception. SEARCH STRATEGY: We searched the following computerized databases from inception to July 2004 for randomized controlled trials of spermicides for contraception: Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, POPLINE, LILACS, and EMBASE. We examined the reference list of each trial found as well as that of review articles and textbook chapters. SELECTION CRITERIA: We included any trial of a commercial product used alone for contraception. Each included trial must have provided sufficient information to determine pregnancy rates. We located reports from 14 trials. DATA COLLECTION AND ANALYSIS: Two reviewers independently extracted information from the trials identified. We did not conduct a meta-analysis, since most trials had large losses to follow-up. We entered the data into tables and presented the results descriptively. MAIN RESULTS: In the largest trial to date, the gel (Advantage S) containing the lowest dose of nonoxynol-9 (52.5 mg) was significantly less effective in preventing pregnancy than were gels with higher doses of the same agent (100 mg and 150 mg). Probabilities of pregnancy by six months were 22% for the 52.5 mg gel, 16% for the 100 mg dose, and 14% for the 150 mg dose. In the same trial, the three different vehicles with 100 mg of nonoxynol-9 had similar efficacy. Interpretation of these figures is limited, since 39% of participants discontinued the method or were lost from the trial. Few important differences in efficacy emerged in other trials. AUTHORS' CONCLUSIONS: The probability of pregnancy varied widely in reported trials. A gel containing nonoxynol-9 52.5 mg was inferior to two other products tested in the largest trial. Aside from this finding, personal characteristics and behavior of users may be more important than characteristics of the spermicide products in determining the probability of pregnancy. Gel was liked more than the film or vaginal suppository in the largest trial. Spermicide trials have the dual challenges of difficult recruitment and high discontinuation rates; the latter threatens trial validity.

Contraception↗

PubMed2004

Revealing the roles of Hamiltonian coupling in bound-state quantum systems.

A Hamiltonian coupling identification (HCI) technique is introduced to reveal the independent and cooperative roles of Hamiltonian matrix elements in determining the bound-state energies of quantum systems. The HCI technique operates by encoding each Hamiltonian matrix element with a unique modulation signal, producing a nonlinear signature in the energy eigenvalues that may be decoded to reveal the contributing coupling structure in the Hamiltonian. The HCI technique is capable of exploring the roles of Hamiltonian coupling structure within and beyond the convergence limits of standard perturbation theory expansions. The flexibility residing in the encoding and decoding processes may be exploited to tailor the analysis to meet the desired degree of sought-after information about the Hamiltonian coupling structure. HCI, based on a Fourier encoding and decoding scheme, is illustrated by extracting information on the role of coupling interactions in the potential matrix elements of several simple model systems.

Journal Article↗

PubMed2005

Function of a fly motion-sensitive neuron matches eye movements during free flight.

Sensing is often implicitly assumed to be the passive acquisition of information. However, part of the sensory information is generated actively when animals move. For instance, humans shift their gaze actively in a sequence of saccades towards interesting locations in a scene. Likewise, many insects shift their gaze by saccadic turns of body and head, keeping their gaze fixed between saccades. Here we employ a novel panoramic virtual reality stimulator and show that motion computation in a blowfly visual interneuron is tuned to make efficient use of the characteristic dynamics of retinal image flow. The neuron is able to extract information about the spatial layout of the environment by utilizing intervals of stable vision resulting from the saccadic viewing strategy. The extraction is possible because the retinal image flow evoked by translation, containing information about object distances, is confined to low frequencies. This flow component can be derived from the total optic flow between saccades because the residual intersaccadic head rotations are small and encoded at higher frequencies. Information about the spatial layout of the environment can thus be extracted by the neuron in a computationally parsimonious way. These results on neuronal function based on naturalistic, behaviourally generated optic flow are in stark contrast to conclusions based on conventional visual stimuli that the neuron primarily represents a detector for yaw rotations of the animal.

Animals↗

PubMed1999

Midbrain combinatorial code for temporal and spectral information in concurrent acoustic signals.

All vocal species, including humans, often encounter simultaneous (concurrent) vocal signals from conspecifics. To segregate concurrent signals, the auditory system must extract information regarding the individual signals from their summed waveforms. During the breeding season, nesting male midshipman fish (Porichthys notatus) congregate in localized regions of the intertidal zone and produce long-duration (>1 min), multi-harmonic signals ("hums") during courtship of females. The hums of neighboring males often overlap, resulting in acoustic beats with amplitude and phase modulations at the difference frequencies (dFs) between their fundamental frequencies (F0s) and harmonic components. Behavioral studies also show that midshipman can localize a single hum-like tone when presented with a choice between two concurrent tones that originate from separate speakers. A previous study of the neural mechanisms underlying the segregation of concurrent signals demonstrated that midbrain neurons temporally encode a beat's dF through spike synchronization; however, spectral information about at least one of the beat's components is also required for signal segregation. Here we examine the encoding of spectral differences in beat signals by midbrain neurons. The results show that, although the spike rate responses of many neurons are sensitive to the spectral composition of a beat, virtually all midbrain units can encode information about differences in the spectral composition of beat stimuli via their interspike intervals (ISIs) with an equal distribution of ISI spectral sensitivity across the behaviorally relevant dFs. Together, temporal encoding in the midbrain of dF information through spike synchronization and of spectral information through ISI could permit the segregation of concurrent vocal signals.

Acoustic Stimulation↗

PubMed2004

Improving identification of differentially expressed genes in microarray studies using information from public databases.

We demonstrate that the process of identifying differentially expressed genes in microarray studies with small sample sizes can be substantially improved by extracting information from a large number of datasets accumulated in public databases. The improvement comes from more reliable estimates of gene-specific variances based on other datasets. For a two-group comparison with two arrays in each group, for example, the result of our method was comparable to that of a t-test analysis with five samples in each group or to that of a regularized t-test analysis with three samples in each group. Our results are further improved by weighting the results of our approach with the regularized t-test results in a hybrid method.

Databases, Genetic↗

PubMed2006

Effects of early treatment with statins on short-term clinical outcomes in acute coronary syndromes: a meta-analysis of randomized controlled trials.

CONTEXT: The short-term effects of early treatment with statins in patients after the onset of acute coronary syndromes (ACS) for the outcomes of death, myocardial infarction (MI), and stroke are unclear. OBJECTIVE: To evaluate relevant outcomes of patients from randomized controlled trials comparing early statin therapy with placebo or usual care at 1 and 4 months following ACS. DATA SOURCES AND STUDY SELECTION: Systematic search of electronic databases (MEDLINE, EMBASE, PASCAL, Cochrane Central Register) from their inception to August 2005, which was supplemented by contact with experts in the field. Two reviewers independently determined the eligibility of randomized controlled trials that compared treatment with statins with a control, were initiated within 14 days after onset of ACS, and had a minimal follow-up of 30 days. Trials with cerivastatin were only included in a sensitivity analysis. DATA EXTRACTION: Information on baseline characteristics of included trials and patients, reported methodological quality, lipid levels, and clinical outcome was independently extracted by 2 investigators. Investigators from each included trial contributed additional data if necessary. DATA SYNTHESIS: Twelve trials involving 13 024 patients with ACS were included in the meta-analysis. The risk ratios for the combined end point of death, MI, and stroke for patients treated with early statin therapy compared with control therapy were 0.93 (95% confidence interval [CI], 0.80-1.09; P = .39) at 1 month and 0.93 (95% CI, 0.81-1.07; P = .30) at 4 months following ACS. There were no statistically significant risk reductions from statins for total death, total MI, total stroke, cardiovascular death, fatal or nonfatal MI, or revascularization procedures (percutaneous coronary intervention or coronary artery bypass graft surgery). Sensitivity analyses with restriction to trials of high quality or with additional data from a large trial using cerivastatin indicated summary risk ratios even closer to 1. CONCLUSION: Based on available evidence, initiation of statin therapy within 14 days following onset of ACS does not reduce death, MI, or stroke up to 4 months.

Angina, Unstable↗

PubMed1989

Querying medical databases in an environment offering logical data independence.

Medical information systems are becoming popular. Furthermore, their use is expected to be expanded in future. In order to easily extract information from the underlying databases, easy to use man-machine interfaces are required. This paper concerns the doctor interface of the ARPIA medical information system based on a relational database management system. The whole system is currently used inside the Outpatient Pediatric Clinic of the Catholic University of Rome, Italy. The interface provides logical data independence towards the underlying relational database. The paper contains some background about this kind of interfaces, and also, it sketches the software architecture of the implemented prototype.

Database Management Systems↗

PubMed2005

Managing educational resource in medicine: system design and integration.

The objective of this paper is to describe our experience in developing a tool based on web technologies, for storing, managing and providing medical courses written by professors in the medical university of Rennes. The increasing number of documents sent by professors leaded us to build a specific resource management system. We created a relational database, containing all meta information about each available document. Professors provide their courses in various formats. We use natural language parsing techniques to extract information from the text, and provide a proper semantic indexation which will be used by a medical-specific search engine. Then the content of our database is dynamically displayed on a web interface. A user's directory identifies teachers and students, controls the access, tracks the students' navigation and allows an on-line discussion forum. This portal contains 524 courses and we had more than 3,000,000 connections on it last year. We are now integrating its content using the semantic web approach in a larger project: the French Virtual Medical University.

Computer Security↗

PubMed1999

Classification algorithms applied to narrative reports.

Narrative text reports represent a significant source of clinical data. However, the information stored in these reports is inaccessible to many automated decision support systems. Data mining techniques can assist in extracting information from narrative data. Multiple classification methods, such as rule generation, decision trees, Bayesian classifiers, and information retrieval were used to classify a set of 200 chest X-ray reports according to 6 clinical conditions indicated. A general-purpose natural language processor was used to convert the narrative text into a coded form that could be used by the classification algorithms. Significant differences in performance were found between algorithms. The best performing algorithm applied to the processor output was significantly better than information retrieval applied to raw text. Predictor variables from the coded processor output were limited to avoid overfitting. Methods that limited by domain knowledge performed significantly better than those that limited by conditional probabilities of the variables in the training set. Algorithms were also shown to be dependent on training set size.

Algorithms↗

PubMed1996

Interval-censored event history analysis.

"Event history analysis...has [over time] branched out in two directions: on the one hand, surveys collecting retrospective information on respondent's life course, family and occupational histories, residential mobility...; on the other, individual biographies compiled by extracting information from administrative sources (vital registration data, census schedules, notifications of residence...). Each method has constraints--the second, in particular, because of depending on the availability of administrative data: job changes are never registered and in France, neither are residential moves. That limits observation to the information collected when a census is held or a vital event registered. [The authors] test here the validity of these incomplete data by comparing them to information supplied by an ad hoc survey."

Data Collection↗

PubMed2005

Abciximab as adjunctive therapy to reperfusion in acute ST-segment elevation myocardial infarction: a meta-analysis of randomized trials.

CONTEXT: The benefits of abciximab in patients with ST-segment elevation myocardial infarction (STEMI) are still a matter of debate. OBJECTIVE: To combine data from all randomized trials conducted with abciximab in STEMI. DATA SOURCES: Formal searches of electronic databases (MEDLINE, PubMed) from from January 1990 to December 2004. STUDY SELECTION: We examined all completed, published, randomized trials of abciximab in STEMI. The following key words were used for study selection: randomized trial, myocardial infarction, reperfusion, primary angioplasty, facilitated angioplasty, stenting, fibrinolysis, IIb-IIIa inhibitors, and abciximab. DATA EXTRACTION: Information on study design, type and dosage of drugs, inclusion and exclusion criteria, number of patients, and clinical outcome was extracted by 2 investigators. Disagreements were resolved by consensus. DATA SYNTHESIS: Eleven trials were analyzed, involving 27115 patients (12,602 [46.5%] in the abciximab group, 14,513 [53.5%] in the control group). When compared with the control group, abciximab was associated with a significant reduction in short-term (30 days) mortality (2.4% vs 3.4%, P = .047) and long-term (6-12 months) mortality (4.4% vs 6.2%, P = .01) in patients undergoing primary angioplasty but not in those treated with fibrinolysis or in all trials combined. Abciximab was associated with a significant reduction in 30-day reinfarction, both in all trials combined (2.1% vs 3.3%, P<.001), in primary angioplasty (1.0% vs 1.9%, P = .03), and in fibrinolysis trials (2.3% vs 3.6%, P<.001). Abciximab did not result in an increased risk of intracranial bleeding (0.61% vs 0.62%, P = .62) but was associated with an increased risk of major bleeding complications when combined with fibrinolysis (5.2% vs 3.1%, P<.001) but not with primary angioplasty (4.7% vs 4.1%, P = .36). CONCLUSIONS: This meta-analysis shows that, when compared with the control group, adjunctive abciximab for STEMI is associated with a significant reduction in 30-day and long-term mortality in patients treated with primary angioplasty but not in those receiving fibrinolysis. The 30-day reinfarction rate is significantly reduced in patients treated with either fibrinolysis or primary angioplasty. A higher risk of major bleeding complications is observed with abciximab in association with fibrinolysis.

Abciximab↗

PubMed2005

A sentence sliding window approach to extract protein annotations from biomedical articles.

BACKGROUND: Within the emerging field of text mining and statistical natural language processing (NLP) applied to biomedical articles, a broad variety of techniques have been developed during the past years. Nevertheless, there is still a great ned of comparative assessment of the performance of the proposed methods and the development of common evaluation criteria. This issue was addressed by the Critical Assessment of Text Mining Methods in Molecular Biology (BioCreative) contest. The aim of this contest was to assess the performance of text mining systems applied to biomedical texts including tools which recognize named entities such as genes and proteins, and tools which automatically extract protein annotations. RESULTS: The "sentence sliding window" approach proposed here was found to efficiently extract text fragments from full text articles containing annotations on proteins, providing the highest number of correctly predicted annotations. Moreover, the number of correct extractions of individual entities (i.e. proteins and GO terms) involved in the relationships used for the annotations was significantly higher than the correct extractions of the complete annotations (protein-function relations). CONCLUSION: We explored the use of averaging sentence sliding windows for information extraction, especially in a context where conventional training data is unavailable. The combination of our approach with more refined statistical estimators and machine learning techniques might be a way to improve annotation extraction for future biomedical text mining applications.

Biomedical Research↗

PubMed2004

Post-reconstruction filtering of positron emission tomography whole-body emission images and attenuation maps using nonlinear diffusion filtering.

RATIONALE AND OBJECTIVES: Positron emission tomography has been playing an important role as a quantitative molecular imaging modality to measure and image biochemical processes in vivo. The quality of positron emission tomography images may impact the accuracy of the quantitative or semiquantitative information extracted from them. MATERIALS AND METHODS: In this study, the anisotropic diffusion filtering technique was used to de-noise emission images and attenuation maps of a whole body for improving the quantitative accuracy of emission images. The efficacy of the filtering technique was shown on a hot-lesion phantom as well as on whole-body emission images and attenuation maps. RESULTS: The filtering technique showed a superb performance on images reconstructed using the iterative and the filtered back-projection reconstruction techniques. CONCLUSION: Filtering may allow the reconstruction of images with optimal parameters with respect to lesion contrast and image resolution by removing the consequential noise. An improvement of as much as six-fold may be attained. It may also improve the accuracy of the quantitative information, such as standard uptake value extracted from emission images.

Anisotropy↗

PubMed1987

Adult age, information processing, and partial report performance.

Previous investigations using the partial report technique for examining adult age differences in iconic memory have suggested that older adults are less able to extract information stored in the icon than are young adults. The present study examined the hypothesis that poorer partial report performance on the part of older adults involves age-related differences in the speed of visual and auditory information processing. Elderly (M = 67 years) and young (M = 23.5 years) adults were contrasted on partial report, whole report, backward masking, and choice reaction time tasks. Results indicated that the older age group exhibited a smaller partial report advantage than did their younger counterparts. This age difference was found to be related in part to increases with age in the time required to encode and identify visual stimuli but was not related to the time required to translate auditory cues into recall instructions. In other words, the slowdown in visual information processing speed that accompanies increased age contributes to age differences in performance on tasks involving iconic memory.

Adult↗

PubMed2002

Complexity analysis of placental blood flow in normal and high-risk pregnancies.

Various strategems of complexity analysis of microvascular blood flow were carried out in several fields of medicine in the past, as such as angiology, ophthalmology and neurology. The introduction of colour-angio-mode, a special form of colour coded Doppler sonography, now makes possible to perform complexity analysis of the placental blood displacement even in the absence of information about hydrodynamic details such as directionality, velocity profile and number of displaced blood cells. Algorithms were developed which allows to extract information concerning the time averaged power of phonon-erythrocytes collision events (from the square of the frequencies of back scattered ultrasound recorded during 166 ms) in 20,000 to 40,000 regions of interest. The obtained values are being displayed as false coloured pixels on a video-screen, we succeeded to obtain quantitative data about displacement rates.In cross-sectional and longitudinal studies we generated typical diagrams displaying the "occurrence rate" of various powers of displacement over time. By this mode of display contour plots can be generated, showing a large amount of low intensity pixels and a small amount of high intensity pixels representing the parenchymatous blood flow inside the placenta. As was to be expected, interdependencies between the placental blood flow and the maternal and fetal heart rates as well as the maternal breathing can be found. While there was only limited influence of maternal and fetal heart rate on the placental blood flow, maternal breathing showed striking influence. Surprisingly, during expiration the power of placental blood movement was decreased, and there was a marked increase during inspiration. In cases of severe intrauterine growth retardation, colour pixel intensities were seen to transiently vanish during end-expiration. The power of placental blood displacement was marked increased subsequent to reducing maternal hematocrit during hemodilution therapy by infusion of artificial colloids. These interdependencies could be confirmed by ex vivo examinations perfusing and percolating the placenta after birth in a hemodynamic model. Additionally, we found interdependencies between fetal and maternal blood displacement inside the placenta. By modelling the decrease of fetal inotropic power in the ex vivo examinations, increase in the power of maternal blood displacement in the intervillous space. The two types of placental blood flow are known to be determined by many factors. While it is currently impossible to measure all these parameters determining an parenchymatous blood flow, it is possible to obtain useful informations about the physiologic and pathophysiologic changes of placental blood flow using colour-angio-mode as a tool of complexity analysis based on the distribution of local blood displacement. This new knowledge can help to understand clinically relevant changes in the individual patient as well their underlying causes.

Female↗

PubMed1997

[The effect of prior information on perception of ongoing behavior of others: information processing at the extraction stage].

This study investigated the effect of prior information on the extraction stage, particularly on the amount of behavior extraction, of information processing when perceiving ongoing behavior of others. In terms of prior information they received, 102 subjects were randomly assigned to three groups: familiarity, desirability, and neutral conditions. Twelve video clips, each about 30 seconds long, of a male stimulus actor in daily life were made. The theme of each clip was one of the three: familiarity, desirability, or activity. The subjects were instructed to form an impression of the male actor, and to press a button when they saw an impression-relevant action and release it when it was over. Results suggested that subjects extracted behavior that was relevant to prior information more frequently, and extraction rates were higher for relevant video clips. However, impression change was found after the observation-extraction task. Hence, it implies that prior information affects the extraction stage, but not the judgment stage, of perceiving ongoing behavior of others.

Adult↗

PubMed2002

BRENDA: a resource for enzyme data and metabolic information.

BRENDA (BRaunschweig ENzyme DAtabase), founded in 1987 by Dietmar Schomburg, is a comprehensive protein function database, containing enzymatic and metabolic information extracted from the primary literature. Presently, the database holds data on more than 40 000 enzymes and 4460 different organisms, and includes information about enzyme-ligand relationships with numerous chemical compounds. The collection of molecular and biochemical information in BRENDA provides a fundamental resource for research in biotechnology, pharmacology, medicinal diagnostics, enzyme mechanics, and metabolism. BRENDA is accessible free of charge to the academic community at http://www.brenda.uni-koeln.de/; commercial users need a license available from http://www.science-factory.com/

Animals↗

PubMed2002

Illusory causation: why it occurs.

Considerable evidence indicates that people overattribute causality to a given stimulus when it is salient or the focus of their attention--the so-called illusory-causation phenomenon. Although illusory causation has proved to be quite robust and generalizable, a compelling explanation for it has not been empirically documented. Four social-attribution studies were conducted to test the hypothesis that illusory causation occurs because salient information is initially registered, or perceptually organized, differently than nonsalient information. The results provide considerable support for the notion that people's literal point of view affects how they initially perceive, or extract, information from an observed interaction, which in turn affects their judgments regarding the causal influence exerted by each interactant.

Adult↗