189 research outputs found

    742-4 Radial Artery Graft: Angiographic Follow-up

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    Interest in the use of the radial artery (RA) as a coronary bypass graft has increased. Attention to harvesting and use of perioperative calcium channel inhibitors have ameliorated problems with spasm noted in earlier studies. Since 1993, 72 patients (pts) underwent grafting using a free RA from the non-dominant forearm. Re-angiography was performed in 24 pts to date and is the subject of this study. Pts ranged from 39–79 years (mean 55.5); all had 2 or 3 vessel disease and an average of 3 grafts/pt were constructed (range 2–4). Left internal thoracic artery (L1TA) was used in all cases except 1. The RA was a single graft in 19 including 2 to the LAD system, 12 to the circumflex system and 5 to the RCA. The RA-was sequential in 5 cases. Of the 24 pts catheterized an average of 9 weeks post-op 24/24 RA's were patent: 1 (sequential) RA had a mid-graft stenosis. There was no spasm seen in any RA. RA distal diameters (2.6mm) were well matched to the recipient vessel (RV) (2.2mm). The ratio RV/graft diameter was 0.83 for the radial artery similar to the ratio for the L1TA (0.90).ConclusionThe RA is a viable coronary conduit, easily harvested and has excellent early patency rates

    A general theorem on angular-momentum changes due to potential vorticity mixing and on potential-energy changes due to buoyancy mixing

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    An initial zonally symmetric quasigeostrophic potential-vorticity (PV) distribution q_i(y) is subjected to complete or partial mixing within some finite zone |y| < L, where y is latitude. The change in M, the total absolute angular momentum, between the initial and any later time is considered. For standard quasigeostrophic shallow-water beta-channel dynamics it is proved that, for any q_i(y) such that dq_i/dy > 0 throughout |y| < L, the change in M is always negative. This theorem holds even when "mixing" is understood in the most general possible sense. Arbitrary stirring or advective rearrangement is included, combined to an arbitrary extent with spatially inhomogeneous diffusion. The theorem holds whether or not the PV distribution is zonally symmetric at the later time. The same theorem governs Boussinesq potential-energy changes due to buoyancy mixing in the vertical. For the standard quasigeostrophic beta-channel dynamics to be valid the Rossby deformation length L_D >> \epsilon L where \epsilon is the Rossby number; when L_D = \infty the theorem applies not only to the beta-channel, but also to a single barotropic layer on the full sphere, as considered in the recent work of Dunkerton and Scott on "PV staircases". It follows that the M-conserving PV reconfigurations studied by those authors must involve processes describable as PV unmixing, or anti-diffusion, in the sense of time-reversed diffusion. Ordinary jet self-sharpening and jet-core acceleration do not, by contrast, require unmixing, as is shown here by detailed analysis. Mixing in the jet flanks suffices. The theorem extends to multiple layers and continuous stratification. A corollary is a new nonlinear stability theorem for shear flows.Comment: 14 pages, 4 figures; Final version, accepted by J. Atmos. Sci, in pres

    Linear dynamics of weakly viscous accretion disks: A disk analog of Tollmien-Schlichting waves

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    This paper discusses new perspectives and approaches to the problem of disk dynamics where, in this study, we focus on the effects of viscous instabilities influenced by boundary effects. The Boussinesq approximation of the viscous large shearing box equations is analyzed in which the azimuthal length scale of the disturbance is much larger than the radial and vertical scales. We examine the stability of a non-axisymmetric potential vorticity mode, i.e. a PV-anomaly. in a configuration in which buoyant convection and the strato-rotational instability do not to operate. We consider a series of boundary conditions which show the PV-anomaly to be unstable both on a finite and semi-infinite radial domains. We find these conditions leading to an instability which is the disk analog of Tollmien-Schlichting waves. When the viscosity is weak, evidence of the instability is most pronounced by the emergence of a vortex sheet at the critical layer located away from the boundary where the instability is generated. For some boundary conditions a necessary criterion for the onset of instability for vertical wavelengths that are a sizable fraction of the layer's thickness and when the viscosity is small is that the appropriate Froude number of the flow be greater than one. This instability persists if more realistic boundary conditions are applied, although the criterion on the Froude number is more complicated. The unstable waves studied here share qualitative features to the instability seen in rotating Blasius boundary layers. The implications of these results are discussed. An overall new strategy for exploring and interpreting disk instability mechanisms is also suggested.Comment: Accepted for publication in Astronomy and Astrophysics. 18 pages. This version 3 with corrected style fil

    Randomized trials fit for the 21st century. A joint opinion from the European Society of Cardiology, American Heart Association, American College of Cardiology, and the World Heart Federation

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    © The Author(s) 2022. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (https://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. The articles are identical except for minor stylistic and spelling differences in keeping with each journal's style. When citing this article, a citation from any of the journals listed is appropriate. For commercial re-use, please contact [email protected] controlled trials are the cornerstone for reliably evaluating therapeutic strategies. However, during the past 25 years, the rules and regulations governing randomized trials and their interpretation have become increasingly burdensome, and the cost and complexity of trials has become prohibitive. The present model is unsustainable, and the development of potentially effective treatments is often stopped prematurely on financial grounds, while existing drug treatments or non-drug interventions (such as screening strategies or management tools) may not be assessed reliably. The current ‘best regulatory practice’ environment, and a lack of consensus on what that requires, too often makes it unduly difficult to undertake efficient randomized trials able to provide reliable evidence about the safety and efficacy of potentially valuable interventions. Inclusion of underrepresented population groups and lack of diversity also remain among the challenges.info:eu-repo/semantics/publishedVersio

    The impact of childhood abuse and recent stress on serum brain-derived neurotrophic factor and the moderating role of BDNF Val66Met

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    Contains fulltext : 98431.pdf (publisher's version ) (Open Access)RATIONALE: Recent findings show lowered brain-derived neurotrophic factor (BDNF) levels in major depressive disorder (MDD). Exposure to stressful life events may (partly) underlie these BDNF reductions, but little is known about the effects of early or recent life stress on BDNF levels. Moreover, the effects of stressful events on BDNF levels may in part be conditional upon a common variant on the BDNF gene (Val(66)Met; RS6265), with the Met allele being associated with a decrease in activity-dependent secretion of BDNF compared to the Val allele. METHODS: We investigated cross-sectionally in 1,435 individuals with lifetime MDD the impact of childhood abuse (CA) and recent life events on serum BDNF levels and assessed whether the impact of these events was moderated by the BDNF Val(66)Met polymorphism. RESULTS: Overall, BDNF Met carriers had reduced serum BDNF levels when exposed to CA in a dose-dependent way. Moreover, exposure to recent life events was also associated with decreases in BDNF levels, but this was independent of BDNF Val(66)Met. Moreover, when not exposed to CA, Met carriers had higher BDNF levels than the Val/Val individuals, who did not show decreases in BDNF associated with CA. Finally, these findings were only apparent in the MDD group without comorbid anxiety. CONCLUSIONS: These gene-environment interactions on serum BDNF levels suggest that Met carriers are particularly sensitive to (early) stressful life events, which extends previous findings on the moderating role of the BDNF Val(66)Met polymorphism in the face of stressful life events

    Cyclic Vomiting Syndrome in 41 adults: the illness, the patients, and problems of management

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    BACKGROUND: Cyclic Vomiting Syndrome (CVS) is a disorder characterized by recurrent, stereotypic episodes of incapacitating nausea, vomiting and other symptoms, separated by intervals of comparative wellness. This report describes the clinical features, co-morbidities and problems encountered in management of 41 adult patients who met the diagnostic criteria for CVS. METHODS: This is a retrospective study of adults with CVS seen between 1994 and 2003. Follow-up data were obtained by mailed questionnaires. RESULTS: Age of onset ranged from 2 to 49 years. The duration of CVS at the time of consultation ranged from less than 1 year to 49 years. CVS episodes were stereotypic in respect of their hours of onset, symptomatology and length. Ninety-three percent of patients had recognizable prodromes. Half of the patients experienced a constellation of symptoms consisting of CVS episodes, migraine diathesis, inter-episodic dyspeptic nausea and a history of panic attacks. Deterioration in the course of CVS is indicated by coalescence of episodes in time. The prognosis of CVS is favorable in the majority of patients. CONCLUSION: CVS is a disabling disorder affecting adults as well as children. Because its occurrence in adults is little known, patients experience delayed or mis-diagnosis and ineffectual, sometimes inappropriately invasive management

    Primary prevention of secondary disorders: A proposal and agenda

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    This paper calls for consideration of a new class of preventive interventions designed explicitly to prevent comorbidity of psychiatric disorders. Epidemiologic data show that successful interventions of this type could be extremely valuable, as up to half of lifetime psychiatric disorders and an even larger percent of chronic and seriously impairing disorders occur to people with a prior history of some other disorder. Furthermore, a review of etiologic hypotheses concerning the causes of comorbidity suggests that interventions aimed at primary prevention of secondary disorders might be feasible. However, more basic risk factor research is needed on the causes of comorbidity before we can make a clear assessment of feasibility and discover promising intervention targets. A number of methodological problems arise in carrying out this type of formative research. These problems are reviewed and suggestions are offered for solutions involving innovations in measurement, design, and data analysis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44044/1/10464_2004_Article_BF00942174.pd
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