831 research outputs found

    A paradigm for restenosis after angioplasty: clues for the development of new preventive therapies

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    Restenosis after intravascular intervention is one of the most important unsolved clinical and economic problems in the management of cardiovascular disease. Although neither its pathogenesis nor its prevention are yet defined, the early and late histologic appearance of the angioplasty state are known. Immediately after angioplasty, the atheroma has fissures, and the normal segment of the vessel circumference is stretched. There is substantial evidence of intimal injury. When restenosis develops at 1-4 months the histologic appearance of the restenotic lesion is intimal hyperplasia. Given this endpoint, we may theorize that the proximate cause of this response is denuding and stretching vascular injury. Since the healing response to tissue injury has been studied extensively, we can hypothesize the major milestones in the temporal sequence of restenosis are platelet aggregation, inflammatory cell infiltration, release of growth factors, medial smooth muscle cell modulation and proliferation, proteoglycan synthesis and extracellular matrix remodeling. At each of these steps, there are potential inhibitors. The resolution of the problem of restenosis may require both removal of atheroma mass and appropriate timing and effective delivery of inhibitors of intimal hyperplasia to the injury site in adequate concentration.Biomedical Reviews 1992; 1: 13-24

    Eigenvalue distributions for some correlated complex sample covariance matrices

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    The distributions of the smallest and largest eigenvalues for the matrix product ZZZ^\dagger Z, where ZZ is an n×mn \times m complex Gaussian matrix with correlations both along rows and down columns, are expressed as m×mm \times m determinants. In the case of correlation along rows, these expressions are computationally more efficient than those involving sums over partitions and Schur polynomials reported recently for the same distributions.Comment: 11 page

    Computer-assisted diagnosis in the noninvasive evaluation of patients with suspected coronary artery disease

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    A microcomputer program called CADENZA, which employs Bayes' theorem to analyze and report the results of various clinical descriptors and noninvasive tests relative to the diagnosis of coronary artery disease, was evaluated in 1,097 consecutive patients without previous myocardial infarction. With this program, each patient was characterized by a probability for coronary artery disease, based on Framingham risk factor analysis, symptom characterization, electrocardiographic stress testing, cardiokymography, cardiac fluoroscopy, thallium perfusion scintigraphy and technetium equilibrium-gated blood pool scintigraphy. A total of 11,808 probability estimates derived from various combinations of the available observations were analyzed: 2,180 in 170 patients undergoing coronary angiography and 9,628 in 969 patients who completed a 1 year follow-up for coronary events.The predicted probability of disease correlated linearly with observed angiographic prevalence in the 170 patients who subsequently had coronary angiography (prevalence = [0.001 ± 0.011] + [0.966 ± 0.019] x probability). The difference between probability and prevalence averaged 3.1%, and the magnitude of this correlation was not affected by the type or amount of data analyzed. The prevalence of multivessel disease in these patients increased as a monotonic function of disease probability. Below a probability of 25%, single vessel disease was slightly more common than multivessel disease. Above a probability of 75%, multivessel disease predominated. In the 969 patients followed up for 1 year from the date of testing, the incidence of cardiac death and nonfatal infarction increased as a cubic function of disease probability (from approximately 0 to 8% per year for each). Above a probability of 90%, however, the standard deviation for predicting these events was wide.These data indicate that Bayes' theorem in general— and CADENZA in particular—is an accurate, clinically applicable means for quantifying the prevalence of angiographic coronary artery disease, the risk of multivessel disease and the incidence of morbid coronary events in the year after testing

    967-21 Long Term Results of Balloon Expandable Slotted-Tube Nitinol Stents in Canine Coronary Arteries

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    This study evaluated delivery performance, quantitative angiographic parameters, intravascular ultrasound appearance. long term patency and vascular histology of radio-opaque, slotted-tube nickel titanium (nitinoll stents permanently implanted in canine coronary arteries. Dogs were treated with aspirin for 1 month. Follow-up angiography and histology were performed at 0.5, 1, 3, and 6 months (number of vessels = 2, 4, 6, and 26, respectively).ResultsThirty-eight of 39 (97%) stents were successfully implanted in the mid LAD and LCX of 20 dogs. One stent, which was undersized, was successfully removed by thermal recovery. Tandem stents were placed in 2 dogs without difficulty. Intravascular ultrasound of 6 stents showed symmetrical expansion with good wall contact. Acute angiographic parameters:nominal stent size (mm)ANOVA p3.03.54.0number42212–inflation pressure (atm)5.5±056.1±1.45.9±1.60.47minimal diameter (mm)2.93±0.073.24±0.143.48±0.160.0003balloon to artery ratio1.23±0.031.25±0.101.25±0.080.65stent to artery ratio1.09±0.031.14±0.091.13±0.070.30percent recoil11.0±1.88.4±1.89.9±1.80.05At follow-up, all vessels and 9 of 9 stented sidebranches were patent. The mean percent stenosis at 3 to 6 months was –1.6±5.2 and the late loss was 0.2±0.3 mm. All struts were covered with neointima at 2 weeks. At 6 months the maximal neointimal thickness was 260±50 μm and was located adjacent to the struts. No thrombi and only occasional areas of granulation tissue with rare inflammatory cells were seen.ConclusionsA slotted tube nitinol stent has delivery performance characteristics and recoil similar to stainless steel slotted-tube stents. Nitinol stents endothelialize rapidly and intimal proliferation is insufficient to create a stenosis in this animal model. These data suggest that a slotted-tube, balloon expandable nitinol stent is sufficiently reliable and biocompatible to warrant clinical trials

    Wishart and Anti-Wishart random matrices

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    We provide a compact exact representation for the distribution of the matrix elements of the Wishart-type random matrices AAA^\dagger A, for any finite number of rows and columns of AA, without any large N approximations. In particular we treat the case when the Wishart-type random matrix contains redundant, non-random information, which is a new result. This representation is of interest for a procedure of reconstructing the redundant information hidden in Wishart matrices, with potential applications to numerous models based on biological, social and artificial intelligence networks.Comment: 11 pages; v2: references updated + some clarifications added; v3: version to appear in J. Phys. A, Special Issue on Random Matrix Theor

    Social gaze in preterm infants may act as an early indicator of atypical lateralization

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    Rachael Davis - ORCID: 0000-0002-3887-6003 https://orcid.org/0000-0002-3887-6003VoR deposited and AM unrestricted on 2022-02-10.Visual field biases have been identified as markers of atypical lateralisation in children with developmental conditions, but this is the first investigation to consider early lateralised gaze behaviours for social stimuli in preterm infants. Eyetracking methods with 51 preterm (33 male, 92.1% White) and 61 term-born (31 male, 90.1% White) infants aged 8-10 months from Edinburgh, UK, captured the development of visual field biases, comparing gaze behaviour to social and non-social stimuli on the left versus right of the screen. Preterm infants showed a significantly reduced interest to social stimuli on the left versus right compared to term children (d =.58). Preterm children exhibit early differential orienting preferences that may be an early indicator of atypical lateralised function.This work is a secondary analysis of data collected from Theirworld Edinburgh Birth Cohort, which is supported by Theirworld (www.theirworld.org) and is carried out in the MRC Centre for Reproductive Health at the University of Edinburgh (MRC G1002033).https://doi.org/10.1111/cdev.13734aheadofprintaheadofprin

    Containment - exploring the concept of agency in children’s statutory encounters with social workers

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    This article examines children’s agency in their interactions with social workers during statutory encounters in a child protection context. It draws from a UK wide ethnographic study. It finds that much of social workers’ responses to children’s agency in this context are best understood as a form of ‘containment’. In doing so, it offers an original and significant contribution to the theoretical understanding of children’s agency, as well as its application in social work practice

    Distribution of metals exposure and associations with cardiometabolic risk factors in the “Modeling the Epidemiologic Transition Study”

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    Background: Metals are known endocrine disruptors and have been linked to cardiometabolic diseases via multiple potential mechanisms, yet few human studies have both the exposure variability and biologically-relevant phenotype data available. We sought to examine the distribution of metals exposure and potential associations with cardiometabolic risk factors in the “Modeling the Epidemiologic Transition Study” (METS), a prospective cohort study designed to assess energy balance and change in body weight, diabetes and cardiovascular disease risk in five countries at different stages of social and economic development. Methods: Young adults (25–45 years) of African descent were enrolled (N = 500 from each site) in: Ghana, South Africa, Seychelles, Jamaica and the U.S.A. We randomly selected 150 blood samples (N = 30 from each site) to determine concentrations of selected metals (arsenic, cadmium, lead, mercury) in a subset of participants at baseline and to examine associations with cardiometabolic risk factors. Results: Median (interquartile range) metal concentrations (μg/L) were: arsenic 8.5 (7.7); cadmium 0.01 (0.8); lead 16.6 (16.1); and mercury 1.5 (5.0). There were significant differences in metals concentrations by: site location, paid employment status, education, marital status, smoking, alcohol use, and fish intake. After adjusting for these covariates plus age and sex, arsenic (OR 4.1, 95% C.I. 1.2, 14.6) and lead (OR 4.0, 95% C.I. 1.6, 9.6) above the median values were significantly associated with elevated fasting glucose. These associations increased when models were further adjusted for percent body fat: arsenic (OR 5.6, 95% C.I. 1.5, 21.2) and lead (OR 5.0, 95% C.I. 2.0, 12.7). Cadmium and mercury were also related with increased odds of elevated fasting glucose, but the associations were not statistically significant. Arsenic was significantly associated with increased odds of low HDL cholesterol both with (OR 8.0, 95% C.I. 1.8, 35.0) and without (OR 5.9, 95% C.I. 1.5, 23.1) adjustment for percent body fat. Conclusions: While not consistent for all cardiometabolic disease markers, these results are suggestive of potentially important associations between metals exposure and cardiometabolic risk. Future studies will examine these associations in the larger cohort over time
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