Confounding by indication: an example of variation in the use of epidemiologic terminology.
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Confounding by indication is a term used when a variable is a risk factor for a disease among nonexposed persons and is associated with the exposure of interest in the population from which the cases derive, without being an intermediate step in the causal pathway between the exposure and the disease. However, in the literature, the term confounding by indication is not always used consistently. The authors found three different situations in which the term has been applied or might have been used but was not: confounding by indication as protopathic bias, as confounding by severity, or as a form of selection bias. It might be helpful to limit use of the term confounding by indication to the situation in which the disease that forms the indication acts as a confounder irrespective of its severity and to apply the term confounding by severity if the severity of this disease acts as a confounder. Protopathic bias and selection bias should not be confused with these terms. The use of appropriate terms ultimately will improve communication among researchers and contribute to the clarity of their papers. (+info)
The classification of smile patterns.
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Although "smile therapy" is still in its infancy, society has already placed a great demand on dentists to evaluate and treat smiles. The smile classification scheme and vocabulary presented in this article will aid in discussions between patient and dentist regarding esthetic treatment. (+info)
Characterization and proposed nomenclature of epidemic strains of methicillin-resistant Staphylococcus aureus in Canada.
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We hope that standardized nomenclature for identifying epidemic MRSA strains prevalent in Canadian hospitals will be helpful to physicians and infection control practitioners attempting to understand and control the spread of the organism in health-care facilities. It is anticipated that as MRSA continues to evolve in Canadian health-care facilities other strains may be recognized as "epidemic"; as these strains become better characterized they may be added to those designated above. Laboratory physicians and infection control personnel are invited to submit strains that may warrant characterization and designation as a Canadian epidemic strain to the Laboratory Centre for Disease Control, Health Canada, Winnipeg, Manitoba. (+info)
A high-density integrated genetic linkage and radiation hybrid map of the laboratory rat.
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The laboratory rat (Rattus norvegicus) is a key animal model for biomedical research. However, the genetic infrastructure required for connecting phenotype and genotype in the rat is currently incomplete. Here, we report the construction and integration of two genomic maps: a dense genetic linkage map of the rat and the first radiation hybrid (RH) map of the rat. The genetic map was constructed in two F2 intercrosses (SHRSP x BN and FHH x ACI), containing a total of 4736 simple sequence length polymorphism (SSLP) markers. Allele sizes for 4328 of the genetic markers were characterized in 48 of the most commonly used inbred strains. The RH map is a lod >/= 3 framework map, including 983 SSLPs, thereby allowing integration with markers on various genetic maps and with markers mapped on the RH panel. Together, the maps provide an integrated reference to >3000 genes and ESTs and >8500 genetic markers (5211 of our SSLPs and >3500 SSLPs developed by other groups). [Bihoreau et al. (1997); James and Tanigami, RHdb (http:www.ebi.ac.uk/RHdb/index.html); Wilder (http://www.nih.gov/niams/scientific/ratgbase); Serikawa et al. (1992); RATMAP server (http://ratmap.gen.gu.se)] RH maps (v. 2.0) have been posted on our web sites at http://goliath.ifrc.mcw.edu/LGR/index.html or http://curatools.curagen.com/ratmap. Both web sites provide an RH mapping server where investigators can localize their own RH vectors relative to this map. The raw data have been deposited in the RHdb database. Taken together, these maps provide the basic tools for rat genomics. The RH map provides the means to rapidly localize genetic markers, genes, and ESTs within the rat genome. These maps provide the basic tools for rat genomics. They will facilitate studies of multifactorial disease and functional genomics, allow construction of physical maps, and provide a scaffold for both directed and large-scale sequencing efforts and comparative genomics in this important experimental organism. (+info)
Myofibroblasts. I. Paracrine cells important in health and disease.
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Myofibroblasts are a unique group of smooth-muscle-like fibroblasts that have a similar appearance and function regardless of their tissue of residence. Through the secretion of inflammatory and anti-inflammatory cytokines, chemokines, growth factors, both lipid and gaseous inflammatory mediators, as well as extracellular matrix proteins and proteases, they play an important role in organogenesis and oncogenesis, inflammation, repair, and fibrosis in most organs and tissues. Platelet-derived growth factor (PDGF) and stem cell factor are two secreted proteins responsible for differentiating myofibroblasts from embryological stem cells. These and other growth factors cause proliferation of myofibroblasts, and myofibroblast secretion of extracellular matrix (ECM) molecules and various cytokines and growth factors causes mobility, proliferation, and differentiation of epithelial or parenchymal cells. Repeated cycles of injury and repair lead to organ or tissue fibrosis through secretion of ECM by the myofibroblasts. Transforming growth factor-beta and the PDGF family of growth factors are the key factors in the fibrotic response. Because of their ubiquitous presence in all tissues, myofibroblasts play important roles in various organ diseases and perhaps in multisystem diseases as well. (+info)
Living anatomy of the atrioventricular junctions. A guide to electrophysiological mapping. A Consensus Statement from the Cardiac Nomenclature Study Group, Working Group of Arrythmias, European Society of Cardiology, and the Task Force on Cardiac Nomenclature from NASPE. North American Society of Pacing and Electrophysiology.
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Current nomenclature for atrioventricular junctions derives from a surgically distorted view, placing the valvar rings and the triangle of Koch in a single plane with antero-posterior and right-left lateral coordinates. Within this convention, the aorta is considered to occupy an anterior position, while the mouth of the coronary sinus is shown as being posterior. While this nomenclature has served its purpose for the description and treatment of arrhythmias dependent on accessory pathways and atrioventricular nodal re-entry, it is less than satisfactory for the description of atrial and ventricular mapping. To correct these deficiencies, a consensus document has been prepared by experts from the Working Group of Arrhythmias of the European Society of Cardiology, and the North American Society of Pacing and Electrophysiology. It proposes a new, anatomically sound, nomenclature that will be applicable to all chambers of the heart. In this report, we discuss its value as regards the description of the atrioventricular junctions, establishing the principles of this new nomenclature. (+info)
The heritability of malocclusion: Part 1--Genetics, principles and terminology.
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The relative contribution of genes and the environment to the aetiology of malocclusion has been a matter of controversy throughout the twentieth century. Genetic mechanisms are clearly predominant during embryonic craniofacial morphogenesis, but environment is also thought to influence dentofacial morphology postnatally, particularly during facial growth. Orthodontic and orthopaedic techniques are used in the treatment of malocclusion and other dentofacial deformities, but with limited effectiveness. The key to the determination of the aetiology of malocclusion, and its treatability lies in the ability to differentiate the effect of genes and environment on the craniofacial skeleton in a particular individual. Our ability to do this is limited by our lack of knowledge on the genetic mechanisms that control facial growth and lack of scientific evidence for the influence of environmental factors on human craniofacial morphogenesis. (+info)
Para-articular chondroma and osteochondroma of the infrapatellar fat pad: a report of three cases.
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We report three cases of para-articular chondroma and osteochondroma in the region of infrapatellar fat pad. All three lesions were resected and examined histologically. Two of them were primarily cartilaginous with a lobular pattern internally, and one uniformly osseous with peripheral cartilage. We conclude that these lesions are not the same. The former should be designated para-articular chondroma after Jaffe and the latter, osteochondroma. (+info)