Search results for "annulus"
showing 10 items of 26 documents
Do otolith annular structures correspond to the first freshwater entry for yellow European eelsAnguilla anguillain the Baltic countries?
2010
To examine the relationship between freshwater entry and otolith annular structures, a total of 113 naturally recruited European eels Anguilla anguilla from Lithuania and Latvia that entered fresh water at least once were collected. In some individuals (8.3-11.3%), the first freshwater entry coincided with a dark check that was distinctly different from neighbouring annuli. In most individuals (81.7-84.9%), the first freshwater entry occurred on rings and increments indistinguishable from other annuli. For the remaining individuals (3.8-10%), the first freshwater entry did not correspond to any otolith ring, band or annulus. According to recent evidence, the observed high correspondence bet…
Androglobin, a chimeric mammalian globin, is required for male fertility
2022
AbstractSpermatogenesis is a highly specialised process, involving multiple dedicated pathways and regulatory check-points. Defects ultimately lead to male sub-fertility or sterility, and numerous aspects of mammalian sperm formation remain unknown. The predominant expression of the latest globin family member, androglobin (Adgb) in mammalian testis tissue prompted us to assess its physiological function in spermatogenesis. Adgb knockout mice display male infertility, reduced testis weight, impaired maturation of elongating spermatids, abnormal sperm shape and ultrastructural defects in microtubule and mitochondrial organisation. Epididymal sperm from Adgb knockout animals display multiple …
Immediate effect of the MitraClip procedure on mitral ring geometry in primary and secondary mitral regurgitation.
2013
Percutaneous treatment of mitral regurgitation (MR) has been shown to reduce MR severity and improve functional outcomes. Surgical treatment of MR usually includes mitral annulus reduction. The influence of the MitraClip w on annulus geometry is not clear. We wanted to investigate whether the procedure itself reduces annulus diameter and if there may be differences between secondary or functional (SMR) and primary (PMR) MR. Methods and results We retrospectively assessed 3D echocardiography (3D-TEE) data of 55 patients acquired during the procedure shortly before and after clip placement for changes in annulus diameter and area. Measurements were done with QLAB software. Patients were categ…
Pseudo-rotations of the closed annulus : variation on a theorem of J. Kwapisz
2003
Consider a homeomorphism h of the closed annulus S^1*[0,1], isotopic to the identity, such that the rotation set of h is reduced to a single irrational number alpha (we say that h is an irrational pseudo-rotation). For every positive integer n, we prove that there exists a simple arc gamma joining one of the boundary component of the annulus to the other one, such that gamma is disjoint from its n first iterates under h. As a corollary, we obtain that the rigid rotation of angle alpha can be approximated by homeomorphisms conjugate to h. The first result stated above is an analog of a theorem of J. Kwapisz dealing with diffeomorphisms of the two-torus; we give some new, purely two-dimension…
Spiral conical approximations to double reflection Wolter optics
2008
The design of a grazing incidence focusing optic obtained from a spiral approximation to multiple nested cones produces an annular image of a point source. The angular size of the annulus depends mainly on the pitch of the winding and the focal length. For a spiral conical approximation to Wolter optics, the effect is magnified by the double reflection. However, if the two conical spirals are wound one clock-wise and the other counter-clock-wise, then the aberration is partially compensated. We use a ray tracing code to evaluate advantages and disadvantages of this optical design for potential applications of a light weight optics technology based on plastic foils that we are currently inve…
New Technique for Aortic Valve Functional Annulus Reshaping Using a Handmade Prosthetic Ring
2011
Background Despite a wide development in aortic leaflets repair techniques, aortic valve annuloplastic procedures are still poorly investigated. We present our aortic valve annuloplastic system consisting of a handmade prosthetic ring with 2 components for reshaping the aortic annulus and sinotubular junction (STJ) and illustrates our surgical approach and clinical results. Methods Since February 2003, 45 patients with aortic valve regurgitation underwent aortic annuloplasty using the new ring. Mean patient age was 58 ± 16 years (range, 46 to 76 years). The ring has 2 components: a circular ring used to undersize the circumference of the aortoventricular junction and 3-crown-like shape ring…
Identification of abscess formation in native-valve infective endocarditis using transesophageal echocardiography: implications for surgical treatmen…
1991
The object of the study was to follow patients with endocarditis-associated abscesses in order to evaluate the clinical outcome with and without surgical intervention. Transesophageal echocardiography successfully displayed the location and extent of abscess cavities in 14 patients (group A) with aortic valve endocarditis. The infective process was limited to the perivalvular tissue in two, extended into the ascending aorta in six, and included the interventricular septum, the right ventricular outflow tract, interatrial septum, and/or mitral valve annulus in six patients. The complication rate was significantly higher in group A than in group B, which consisted of 27 patients with proven s…
Transapical beating-heart chordae implantation in mitral regurgitation: a new horizon for repairing mitral valve prolapse
2016
Mitral regurgitation (MR) is increasingly prevalent in western countries despite reduced incidence of rheumatic disease (1,2). MR results from several heterogeneous conditions, including disorders of the valve leaflets, mitral annulus, chordae tendineae, papillary muscles and left ventricle (LV). MR causes are roughly classified as primary (i.e. organic/structural) or secondary (i.e. functional/non-structural) (3).
The annular decay property and capacity estimates for thin annuli
2016
We obtain upper and lower bounds for the nonlinear variational capacity of thin annuli in weighted $\mathbf{R}^n$ and in metric spaces, primarily under the assumptions of an annular decay property and a Poincar\'e inequality. In particular, if the measure has the $1$-annular decay property at $x_0$ and the metric space supports a pointwise $1$-Poincar\'e inequality at $x_0$, then the upper and lower bounds are comparable and we get a two-sided estimate for thin annuli centred at $x_0$, which generalizes the known estimate for the usual variational capacity in unweighted $\mathbf{R}^n$. Most of our estimates are sharp, which we show by supplying several key counterexamples. We also character…
Reoperations After First Lumbar Disk Herniation Surgery with or without Implantation of Mechanical Annular Closure Device
2019
Lumbar diskectomy is a widely performed surgical procedure in patients affected by lumbar disk herniation (LDH). Such a surgical procedure is considered to be safe and able to provide a consistent symptomatic relief in most patients. However, perioperative complications have been reported, ranging from 13% to 15%, and pose a considerable financial burden among patients, hospitals, and national health care agencies. The most common perioperative complication following lumbar diskectomy for disk herniation is the recurrence. Although the recurrence rate of LDH has been reported to be 5%−15%, its exact incidence may be underestimated. Recurrent lumbar disk herniation (rLDH) is defined as disk …