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At least 973 records · Page 54Linked to original sources
PubMed2003

Does this patient have acute cholecystitis?

CONTEXT: Although few patients with acute abdominal pain will prove to have cholecystitis, ruling in or ruling out acute cholecystitis consumes substantial diagnostic resources. OBJECTIVE: To determine if aspects of the history and physical examination or basic laboratory testing clearly identify patients who require diagnostic imaging tests to rule in or rule out the diagnosis of acute cholecystitis. DATA SOURCES: Electronic search of the Science Citation Index, Cochrane Library, and English-language articles from January 1966 through November 2000 indexed in MEDLINE. We also hand-searched Index Medicus for 1950-1965, and scanned references in identified articles and bibliographies of prominent textbooks of physical examination, surgery, and gastroenterology. To identify relevant articles appearing since the comprehensive search, we repeated the MEDLINE search in July 2002. STUDY SELECTION: Included studies evaluated the role of the history, physical examination, and/or laboratory tests in adults with abdominal pain or suspected acute cholecystitis. Studies had to report data from a control group found not to have acute cholecystitis. Acceptable definitions of cholecystitis included surgery, pathologic examination, hepatic iminodiacetic acid scan or right upper quadrant ultrasound, or clinical course consistent with acute cholecystitis and no evidence for an alternate diagnosis. Studies of acalculous cholecystitis were included. Seventeen of 195 identified studies met the inclusion criteria. DATA EXTRACTION: Two authors independently abstracted data from the 17 included studies. Disagreements were resolved by discussion and consensus with a third author. DATA SYNTHESIS: No clinical or laboratory finding had a sufficiently high positive likelihood ratio (LR) or low negative LR to rule in or rule out the diagnosis of acute cholecystitis. Possible exceptions were the Murphy sign (positive LR, 2.8; 95% CI, 0.8-8.6) and right upper quadrant tenderness (negative LR, 0.4; 95% CI, 0.2-1.1), though the 95% CIs for both included 1.0. Available data on diagnostic confirmation rates at laparotomy and test characteristics of relevant radiological investigations suggest that the diagnostic impression of acute cholecystitis has a positive LR of 25 to 30. Unfortunately, the available literature does not identify the specific combinations of clinical and laboratory findings that presumably account for this diagnostic success. CONCLUSIONS: No single clinical finding or laboratory test carries sufficient weight to establish or exclude cholecystitis without further testing (eg, right upper quadrant ultrasound). Combinations of certain symptoms, signs, and laboratory results likely have more useful LRs, and presumably inform the diagnostic impressions of experienced clinicians. Pending further research characterizing the pretest probabilities associated with different clinical presentations, the evaluation of patients with abdominal pain suggestive of cholecystitis will continue to rely heavily on the clinical gestalt and diagnostic imaging.

Abdomen, Acute↗
PubMed2004

Parasite genome databases and web-based resources.

In the last decade, high-throughput genome sequencing and complementary techniques such as microarray and proteomics have generated, and will continue to generate, ever-increasing amounts of data. These technologies of gene discovery, expression, and functional analysis have been applied to a vast array of organisms, including parasites. In most instances, the data are freely available via the Internet, and researchers are becoming increasingly reliant on up-to-date, centralized data repositories to complement wet bench science. This chapter presents an overview of resources relevant to researchers with an interest in para-site genomics and biology. After briefly touching on some of the publicly available nucleotide and protein sequence as well as domain databases, the focus turns to parasite genome projects and associated Web-based resources. A list of parasite sequencing projects current at the time of writing, including relevant Web site addresses, is provided. The available resources range from network sites and project pages at sequencing institutes to databases that integrate and curate sequence data and associated annotation with diverse biological datasets. Particular attention is given to three databases, GeneDB (http://www.genedb.org/), PlasmoDB (http://plasmodb. org/), and tigr db, detailing the scope of each database and the tools available for data querying and retrieval.

Animals↗
PubMed1998

Endothelial dysfunction: implications for therapy of cardiovascular diseases.

OBJECTIVE: To review current literature regarding endothelial dysfunction in cardiovascular diseases and examine implications of these findings for the treatment of various cardiovascular disorders. DATA SOURCE: A MEDLINE search of basic science articles pertinent to understanding the role of the endothelium in the atherosclerotic process and of clinical trials examining the presence and treatment of impaired endothelium-dependent vascular relaxation was conducted. STUDY SELECTION: Selected basic science articles and reviews were included to explain the foundation for subsequent clinical trials. All clinical trials examining the treatment of impaired endothelium-dependent vascular relaxation were reviewed. DATA SYNTHESIS: Endothelial dysfunction characterized by impaired endothelium-dependent vascular relaxation is an early physiologic event in atherogenesis. Endothelial dysfunction in peripheral vasculature serves as a marker for impairment in coronary arteries. Techniques for measuring endothelium-dependent vascular relaxation are specific and have a high positive predictive value for coronary artery disease, but low sensitivity. Various pharmacologic agents have been used in an attempt to improve endothelial function, but only lipid-lowering agents and estrogen supplementation have been shown to improve endothelium-dependent vascular relaxation consistently. Treatments used in patients with heart failure or hypertension fail to demonstrate consistent improvement. CONCLUSIONS: Endothelial dysfunction serves as a marker for cardiovascular disease, but pharmacologic treatment does not consistently restore normal endothelial function. Nevertheless, some of these agents are known to have positive clinical outcomes. Future research using these techniques will provide greater insight into the effects of many commonly used therapies for cardiovascular disease on the pathobiology of endothelial dysfunction.

Animals↗
PubMed2005

Comparison of alternative estimation methods in confirmatory factor analyses of the General Health Questionnaire.

This paper examines the implications of violating assumptions concerning the continuity and distributional properties of data in establishing measurement models in social science research. The General Health Questionnaire-12 uses an ordinal response scale. Responses to the GHQ-12 from 201 Hong Kong immigrants on arrival in Australia showed that the data were not normally distributed. A series of confirmatory factor analyses using either a Pearson product-moment or a polychoric correlation input matrix and employing either maximum likelihood, weighted least squares or diagonally weighted least squares estimation methods were conducted on the data. The parameter estimates and goodness-of-fit statistics provided support for using polychoric correlations and diagonally weighted least squares estimation when analyzing ordinal, nonnormal data.

Adolescent↗
PubMed1999

A new method for spectral decomposition using a bilinear Bayesian approach.

A frequent problem in analysis is the need to find two matrices, closely related to the underlying measurement process, which when multiplied together reproduce the matrix of data points. Such problems arise throughout science, for example, in imaging where both the calibration of the sensor and the true scene may be unknown and in localized spectroscopy where multiple components may be present in varying amounts in any spectrum. Since both matrices are unknown, such a decomposition is a bilinear problem. We report here a solution to this problem for the case in which the decomposition results in matrices with elements drawn from positive additive distributions. We demonstrate the power of the methodology on chemical shift images (CSI). The new method, Bayesian spectral decomposition (BSD), reduces the CSI data to a small number of basis spectra together with their localized amplitudes. We apply this new algorithm to a 19F nonlocalized study of the catabolism of 5-fluorouracil in human liver, 31P CSI studies of a human head and calf muscle, and simulations which show its strengths and limitations. In all cases, the dataset, viewed as a matrix with rows containing the individual NMR spectra, results from the multiplication of a matrix of generally nonorthogonal basis spectra (the spectral matrix) by a matrix of the amplitudes of each basis spectrum in the the individual voxels (the amplitude matrix). The results show that BSD can simultaneously determine both the basis spectra and their distribution. In principle, BSD should solve this bilinear problem for any dataset which results from multiplication of matrices representing positive additive distributions if the data overdetermine the solutions.

Adenosine Triphosphate↗
PubMed2005

Questionnaire surveys: methodological and epistemological problems for field-based ethnopharmacologists.

The classical scientific approach is empirical. One of the favoured means of gathering quantitative data in the health and social sciences, including ethnopharmacology and medical ethnobotany, is by use of questionnaires. However, while there are numerous published articles discussing the importance of questionnaire content, the fact that questionnaires themselves may be inappropriate in a number of cultural contexts, even where literacy is not a factor, is usually ignored. In this paper, the authors will address the main issues posed by the use of questionnaire surveys, using case studies based on their own personal experiences as ethnopharmacologists 'in the field'. The pros and cons of qualitative and quantitative research and the use of alternative means to elicit quantitative data will be discussed.

Australia↗
PubMedDate not supplied

The BioImage Database Project: organizing multidimensional biological images in an object-relational database.

The BioImage Database Project collects and structures multidimensional data sets recorded by various microscopic techniques relevant to modern life sciences. It provides, as precisely as possible, the circumstances in which the sample was prepared and the data were recorded. It grants access to the actual data and maintains links between related data sets. In order to promote the interdisciplinary approach of modern science, it offers a large set of key words, which covers essentially all aspects of microscopy. Nonspecialists can, therefore, access and retrieve significant information recorded and submitted by specialists in other areas. A key issue of the undertaking is to exploit the available technology and to provide a well-defined yet flexible structure for dealing with data. Its pivotal element is, therefore, a modern object relational database that structures the metadata and ameliorates the provision of a complete service. The BioImage database can be accessed through the Internet.

Copyright↗
PubMed2004

Cardiovascular effects of raloxifene: the arterial and venous systems.

BACKGROUND: Cardiovascular disease caused by atherosclerosis is the largest single killer of women. Prior observational data had suggested that hormone therapy may have cardioprotective effects. METHODS: Data from clinical trials and basic science studies were evaluated to assess the cardiovascular effects of hormone therapy and selective estrogen replacement modulators. RESULTS: Hormone therapy does not appear to lower the risk of cardiovascular events in older postmenopausal women. Selective estrogen receptor modulators (SERMS) have been approved for human use; tamoxifen is used for treatment and prevention of breast cancer and raloxifene is used for the treatment and prevention of osteoporosis. Raloxifene is the only SERM being specifically studied for its effects on coronary heart disease events in a prospective, randomized, controlled trial. CONCLUSIONS: Although raloxifene does increase venous thromboembolic events, there is suggestive data that it may have favorable effects on the arterial systems in women. Only compelling positive data from the Raloxifene Use for The Heart (RUTH) trial will lead to greater use of SERMS to potentially lower the risk of atherosclerotic vascular disease.

Arteries↗
PubMed2003

Simplicity: a unifying principle in cognitive science?

Much of perception, learning and high-level cognition involves finding patterns in data. But there are always infinitely many patterns compatible with any finite amount of data. How does the cognitive system choose 'sensible' patterns? A long tradition in epistemology, philosophy of science, and mathematical and computational theories of learning argues that patterns 'should' be chosen according to how simply they explain the data. This article reviews research exploring the idea that simplicity drives a wide range of cognitive processes. We outline mathematical theory, computational results and empirical data that underpin this viewpoint.

Journal Article↗
PubMed2005

Statistical signals in bioinformatics.

The Arthur M. Sackler Colloquium of the National Academy of Sciences, "Frontiers in Bioinformatics: Unsolved Problems and Challenges," organized by David Eisenberg, Russ Altman, and myself, was held October 15-17, 2004, to provide a forum for discussing concepts and methods in bioinformatics serving the biological and medical sciences. The deluge of genomic and proteomic data in the last two decades has driven the creation of tools that search and analyze biomolecular sequences and structures. Bioinformatics is highly interdisciplinary, using knowledge from mathematics, statistics, computer science, biology, medicine, physics, chemistry, and engineering.

Animals↗
PubMed1993

Clinical and experimental results as a basis of surgical practice.

Since John Hunter first applied the scientific approach to surgery in the late 18th century, it has been raised from the humble level of a handicraft to a highly experimental science. Although surgical research is essential, the practice of surgery has always been much influenced by the basic sciences. The clinical significance of experimental data has often only been recognized years later: research to no pre-defined end is also of utmost importance. Today, in a time of cost explosion and overabundance of information, cooperative and statistically well-planned studies are essential to optimize financial and physical resources. Fields of increasing interest such as gene technology, immunology and preventive medicine will influence surgery in the near future. Minimal invasive and interventional techniques have already started to revolutionize surgical practice. So surgical research today combines traditional medicine and modern techniques to put into practice immediately. If surgeons consider their field to be a unity of "craftsmanship, art and science" [10] and at the same time adhere to the rules of ethics, they will comply with the principle of "saluti et solatio aegrorum".

Austria↗
PubMed1999

[On the problems of fitting linear regression models for hierarchically structured data in medical research].

There are a large number of the hierarchically structured data in the field of medical sciences, which have been analyzed usually by conventional linear regression models. The objective of this paper is to explore the problems and the relationship of parameter estimates of the three common linear regression models in fitting the hierarchically structured date, and the correction of the precision of parameter estimates. It is shown that the estimate of parameter and it's precision of linear regression models is related to the variation of independent variable between and within level 2 units, and the difference of residual estimates is associated with the difference of parameter estimates. The three common linear regression models are all inappropriate for the hierarchically structured data, but the standard error of the level 1 combined model can be corrected by variance inflation factor in conditions.

Analysis of Variance↗
PubMed1984

The Aachen clinical hemorheology test profile: a proposal for the documentation of hemorheological data in clinical medicine.

The recent development of specific methods to measure directly the microrheological determinants of blood fluidity allows to complement or even substitute global measurements of whole blood apparent viscosity or filtrability through sieves containing restricted pores. While such differentiation is mandatory for practical and theoretical reasons, there is the danger of loosing coherence of measurements essential for correlating hemorheology to other sciences. In an attempt to document hemorheological data in a simple yet comprehensive fashion, a test profile for the display of normalized data from subtests on hematocrit, plasma viscosity, red cell "rigidity" and tendency to red cell aggregation is proposed. Using procedures developed in the behavioural sciences, stringend criteria for evaluating the validity, reliability, standardization, economy and usefulness of individual subtests for the blood viscosity determinants and a compounded hemorheology test profile are proposed. There is good evidence that abnormal hemorheological behaviour of red cell plasma mixtures manifest themselves exclusively in situations associated with grossly reduced in vivo driving pressures and thence shear stresses. In these situations, in which a low flow state is caused by general hemodynamic changes, there is a danger that the blood looses its normal fluidity and undergoes a reversible viscidation: We propose the hypothesis that in these situation abnormally blood poses a risk of a flow limitation (and even interruption) by rheological abnormalities described above. The test profile presented has been developed to supply a more valid experimental method for subjecting the above hypothesis to experimental tests in the clinical situation.

Blood Physiological Phenomena↗
PubMed1996

Importance of cerebrovascular disease in studies of myocardial infarction.

BACKGROUND AND PURPOSE: Myocardial infarction and stroke are both predominantly manifestations of atherosclerosis, yet stroke is commonly ignored in prognostic studies and therapeutic trials of ischemic heart disease. Our objective was to assess, in a community setting, the relative importance of stroke among patients at high risk for myocardial infarction. METHODS: We analyzed 1985 survey data from the National Academy of Science Twin Registry of white male veterans. To minimize confounding by genetic and environmental factors, we restricted our analysis to the rates of stroke and myocardial infarction among monozygotic twins counted as individuals or as twin pairs. RESULTS: Among 2764 monozygotic twins aged 58 to 68 years, the overall rate of myocardial infarction was 10% and stroke 3.1%. Among 2632 individual monozygotic twins (95%) with complete responses, the rate of stroke among men with a history of myocardial infarction was 7.5% (17/228) compared with 2.4% (58/2404) among those without myocardial infarction (odds ratio = 3.3, chi square 2 = 19.1, P<.001). A strong association between stroke and myocardial infarction was also found when the data were analyzed for twin pairs (chi square 2 = 135, P<.0005). CONCLUSIONS: Our results suggest that stroke, in addition to myocardial infarction, should be considered as an outcome in clinical investigations of ischemic heart disease.

Aged↗
PubMed2006

Clustered data in sports research.

Clustered, or dependent, data, arise commonly in sports medicine and sports science research, particularly in studies of sports injury and biomechanics, particularly in sports injury trials that are randomised at team or club level, in cross-sectional surveys in which groups of individuals are studied and in studies with repeated measures designs. Clustering, or positive correlation among responses, arises because responses and outcomes from the same cluster will usually be more similar than from different clusters. Study designs with clustering will usually required an increased sample size when compared to those without clustering. Ignoring clustering in statistical analyses can also lead to misleading conclusions, including incorrect confidence intervals and p-values. Appropriate statistical analyses for clustered data must be adopted. This paper gives some examples of clustered data and discusses the implications of clustering on the design and analysis of studies in sports medicine and sports science research.

Cluster Analysis↗