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Sample records for circumferential endocardial extent

  1. Assessment of circumferential endocardial extent of myocardial edema and infarction in patients with reperfused acute myocardial infarction: a cardiovascular magnetic resonance study.

    PubMed

    Ota, Shingo; Tanimoto, Takashi; Hirata, Kumiko; Orii, Makoto; Shiono, Yasutsugu; Shimamura, Kunihiro; Ishibashi, Kohei; Yamano, Takashi; Ino, Yasushi; Kitabata, Hironori; Yamaguchi, Tomoyuki; Kubo, Takashi; Imanishi, Toshio; Akasaka, Takashi

    2014-01-01

    T2 weighted (T2W) images on cardiovascular magnetic resonance (CMR) visualizes myocardial edema, which reflects the myocardial area at risk (AAR) in reperfused acute myocardial infarction (AMI). Late gadolinium enhancement (LGE) demonstrates myocardial infarction. LGE images cover the whole left ventricle, but T2W images are obtained from a few slices of the left ventricle due to the long sequence time, so the quantification of AAR of the entire left ventricle is difficult. We hypothesize that we can quantify AAR with only LGE images if there is a strong correlation between the circumferential endocardial extent of myocardial edema and infarction. Thirty patients with first AMI were enrolled. All patients underwent successfully reperfusion therapy and CMR was performed within the first week after the event. We measured the circumferential extent of edema and infarction on short-axis views (T2 angle and LGE angle), respectively. A total of 82 short-axis slices showed transmural edema on T2W images. Corresponding LGE images were analyzed for the circumferential extent of infarction. The median [interquartile range] of T2 angle and DE angle were 147° [116°-219°] and 134° [104°-200°] in patients with LAD culprit lesion, 91° [87°-101°] and 85° [80°-90°] in LCX, and 110° [94°-123°] and 104° [89°-118°] in RCA, respectively. T2 angle was well correlated with LGE angle (r = 0.99, P < 0.01). There is a strong correlation between the circumferential extent of edema and infarction in reperfused AMI. Thus, T2 weighted imaging can be skipped to quantify the amount of AAR.

  2. Cardiovascular magnetic resonance of the myocardium at risk in acute reperfused myocardial infarction: comparison of T2-weighted imaging versus the circumferential endocardial extent of late gadolinium enhancement with transmural projection.

    PubMed

    Ubachs, Joey F A; Engblom, Henrik; Erlinge, David; Jovinge, Stefan; Hedström, Erik; Carlsson, Marcus; Arheden, Håkan

    2010-03-29

    In the situation of acute coronary occlusion, the myocardium supplied by the occluded vessel is subject to ischemia and is referred to as the myocardium at risk (MaR). Single photon emission computed tomography has previously been used for quantitative assessment of the MaR. It is, however, associated with considerable logistic challenges for employment in clinical routine. Recently, T2-weighted cardiovascular magnetic resonance (CMR) has been introduced as a new method for assessing MaR several days after the acute event. Furthermore, it has been suggested that the endocardial extent of infarction as assessed by late gadolinium enhanced (LGE) CMR can also be used to quantify the MaR. Hence, we sought to assess the ability of endocardial extent of infarction by LGE CMR to predict MaR as compared to T2-weighted imaging. Thirty-seven patients with early reperfused first-time ST-segment elevation myocardial infarction underwent CMR imaging within the first week after percutaneous coronary intervention. The ability of endocardial extent of infarction by LGE CMR to assess MaR was evaluated using T2-weighted imaging as the reference method. MaR determined with T2-weighted imaging (34 +/- 10%) was significantly higher (p < 0.001) compared to the MaR determined with endocardial extent of infarction (23 +/- 12%). There was a weak correlation between the two methods (r2 = 0.17, p = 0.002) with a bias of -11 +/- 12%. Myocardial salvage determined with T2-weighted imaging (58 +/- 22%) was significantly higher (p < 0.001) compared to myocardial salvage determined with endocardial extent of infarction (45 +/- 23%). No MaR could be determined by endocardial extent of infarction in two patients with aborted myocardial infarction. This study demonstrated that the endocardial extent of infarction as assessed by LGE CMR underestimates MaR in comparison to T2-weighted imaging, especially in patients with early reperfusion and aborted myocardial infarction.

  3. Cardiovascular magnetic resonance of the myocardium at risk in acute reperfused myocardial infarction: comparison of T2-weighted imaging versus the circumferential endocardial extent of late gadolinium enhancement with transmural projection

    PubMed Central

    2010-01-01

    Background In the situation of acute coronary occlusion, the myocardium supplied by the occluded vessel is subject to ischemia and is referred to as the myocardium at risk (MaR). Single photon emission computed tomography has previously been used for quantitative assessment of the MaR. It is, however, associated with considerable logistic challenges for employment in clinical routine. Recently, T2-weighted cardiovascular magnetic resonance (CMR) has been introduced as a new method for assessing MaR several days after the acute event. Furthermore, it has been suggested that the endocardial extent of infarction as assessed by late gadolinium enhanced (LGE) CMR can also be used to quantify the MaR. Hence, we sought to assess the ability of endocardial extent of infarction by LGE CMR to predict MaR as compared to T2-weighted imaging. Methods Thirty-seven patients with early reperfused first-time ST-segment elevation myocardial infarction underwent CMR imaging within the first week after percutaneous coronary intervention. The ability of endocardial extent of infarction by LGE CMR to assess MaR was evaluated using T2-weighted imaging as the reference method. Results MaR determined with T2-weighted imaging (34 ± 10%) was significantly higher (p < 0.001) compared to the MaR determined with endocardial extent of infarction (23 ± 12%). There was a weak correlation between the two methods (r2 = 0.17, p = 0.002) with a bias of -11 ± 12%. Myocardial salvage determined with T2-weighted imaging (58 ± 22%) was significantly higher (p < 0.001) compared to myocardial salvage determined with endocardial extent of infarction (45 ± 23%). No MaR could be determined by endocardial extent of infarction in two patients with aborted myocardial infarction. Conclusions This study demonstrated that the endocardial extent of infarction as assessed by LGE CMR underestimates MaR in comparison to T2-weighted imaging, especially in patients with early reperfusion and aborted myocardial

  4. Atrioventricular canal (endocardial cushion defect) (image)

    MedlinePlus

    Endocardial cushion defect is an abnormal heart condition which occurs during the development of the baby. In this condition ... mix causing the heart to work harder. Endocardial cushion defect is strongly associated with several genetic abnormalities.

  5. Circumferential pressure probe

    NASA Technical Reports Server (NTRS)

    Holmes, Harlan K. (Inventor); Moore, Thomas C. (Inventor); Fantl, Andrew J. (Inventor)

    1989-01-01

    A probe for measuring circumferential pressure inside a body cavity is disclosed. In the preferred embodiment, a urodynamic pressure measurement probe for evaluating human urinary sphincter function is disclosed. Along the length of the probe are disposed a multiplicity of deformable wall sensors which typically comprise support tube sections with flexible side wall areas. These are arranged along the length of the probe in two areas, one just proximal to the tip for the sensing of fluid pressure inside the bladder, and five in the sensing section which is positioned within the urethra at the point at which the urinary sphincter constricts to control the flow of urine. The remainder of the length of the probe comprises multiple rigid support tube sections interspersed with flexible support tube sections in the form of bellows to provide flexibility.

  6. BMP2 expression in the endocardial lineage is required for AV endocardial cushion maturation and remodeling.

    PubMed

    Saxon, Jacob G; Baer, Daniel R; Barton, Julie A; Hawkins, Travis; Wu, Bingruo; Trusk, Thomas C; Harris, Stephen E; Zhou, Bin; Mishina, Yuji; Sugi, Yukiko

    2017-10-01

    Distal outgrowth, maturation and remodeling of the endocardial cushion mesenchyme in the atrioventricular (AV) canal are the essential morphogenetic events during four-chambered heart formation. Mesenchymalized AV endocardial cushions give rise to the AV valves and the membranous ventricular septum (VS). Failure of these processes results in several human congenital heart defects. Despite this clinical relevance, the mechanisms governing how mesenchymalized AV endocardial cushions mature and remodel into the membranous VS and AV valves have only begun to be elucidated. The role of BMP signaling in the myocardial and secondary heart forming lineage has been well studied; however, little is known about the role of BMP2 expression in the endocardial lineage. To fill this knowledge gap, we generated Bmp2 endocardial lineage-specific conditional knockouts (referred to as Bmp2 cKO(Endo)) by crossing conditionally-targeted Bmp2(flox/flox) mice with a Cre-driver line, Nfatc1(Cre), wherein Cre-mediated recombination was restricted to the endocardial cells and their mesenchymal progeny. Bmp2 cKO(Endo) mouse embryos did not exhibit failure or delay in the initial AV endocardial cushion formation at embryonic day (ED) 9.5-11.5; however, significant reductions in AV cushion size were detected in Bmp2 cKO(Endo) mouse embryos when compared to control embryos at ED13.5 and ED16.5. Moreover, deletion of Bmp2 from the endocardial lineage consistently resulted in membranous ventricular septal defects (VSDs), and mitral valve deficiencies, as evidenced by the absence of stratification of mitral valves at birth. Muscular VSDs were not found in Bmp2 cKO(Endo) mouse hearts. To understand the underlying morphogenetic mechanisms leading to a decrease in cushion size, cell proliferation and cell death were examined for AV endocardial cushions. Phospho-histone H3 analyses for cell proliferation and TUNEL assays for apoptotic cell death did not reveal significant differences between control

  7. Myocardium and BMP signaling are required for endocardial differentiation.

    PubMed

    Palencia-Desai, Sharina; Rost, Megan S; Schumacher, Jennifer A; Ton, Quynh V; Craig, Michael P; Baltrunaite, Kristina; Koenig, Andrew L; Wang, Jinhu; Poss, Kenneth D; Chi, Neil C; Stainier, Didier Y R; Sumanas, Saulius

    2015-07-01

    Endocardial and myocardial progenitors originate in distinct regions of the anterior lateral plate mesoderm and migrate to the midline where they coalesce to form the cardiac tube. Endocardial progenitors acquire a molecular identity distinct from other vascular endothelial cells and initiate expression of specific genes such as nfatc1. Yet the molecular pathways and tissue interactions involved in establishing endocardial identity are poorly understood. The endocardium develops in tight association with cardiomyocytes. To test for a potential role of the myocardium in endocardial morphogenesis, we used two different zebrafish models deficient in cardiomyocytes: the hand2 mutant and a myocardial-specific genetic ablation method. We show that in hand2 mutants endocardial progenitors migrate to the midline but fail to assemble into a cardiac cone and do not express markers of differentiated endocardium. Endocardial differentiation defects were rescued by myocardial but not endocardial-specific expression of hand2. In metronidazole-treated myl7:nitroreductase embryos, myocardial cells were targeted for apoptosis, which resulted in the loss of endocardial nfatc1 expression. However, endocardial cells were present and retained expression of general vascular endothelial markers. We further identified bone morphogenetic protein (BMP) as a candidate myocardium-derived signal required for endocardial differentiation. Chemical and genetic inhibition of BMP signaling at the tailbud stage resulted in severe inhibition of endocardial differentiation while there was little effect on myocardial development. Heat-shock-induced bmp2b expression rescued endocardial nfatc1 expression in hand2 mutants and in myocardium-depleted embryos. Our results indicate that the myocardium is crucial for endocardial morphogenesis and differentiation, and identify BMP as a signal involved in endocardial differentiation.

  8. Fetal echocardiographic signs of congenital endocardial fibroelastosis.

    PubMed

    Veille, J C; Sivakoff, M

    1988-08-01

    Endocardial fibroelastosis is characterized by a porcelain-like thickening of the endocardium, resulting in a marked increase in echodensity of the endocardium, as well as ventricular dilatation and aortic atresia. With improvement in prenatal ultrasound, this condition can be suspected in utero on the basis of ventricular enlargement, poor ventricular contractility, and marked echodensity of the endocardial surface. We present two cases in which such conditions were found on prenatal M-mode echocardiography and two-dimensional directed pulsed Doppler. Ventriculomegaly and hypocontractility of the ventricle are, however, nonspecific for such conditions; the diagnosis can be made accurately only by pathology. When such findings appear on ultrasound, all efforts should be made to deliver the patient in a perinatal center for optimal neonatal surgery to improve the survival of the newborn.

  9. Placental immaturity, endocardial fibroelastosis and fetal hypoxia.

    PubMed

    Perez, Marie-Hélène; Boulos, Tatiana; Stucki, Pascal; Cotting, Jacques; Osterheld, Maria-Chiara; Di Bernardo, Stefano

    2009-01-01

    We describe a term newborn who, after a normal gestational course, presented at birth with absent cardiac activity and no spontaneous breathing. Death occurred within 30 h. Autopsy revealed placental villous immaturity, multiple acute hypoxic lesions, but also chronic hypoxic lesions like endocardial fibroelastosis. This striking association of endocardial fibroelastosis and placental villous immaturity is reviewed and correlated with 2 other cases of placental villous immaturity that led to in utero death at 39 and 41 weeks of gestation. Placental villous immaturity must be suspected and looked for by both pediatricians and obstetricians in every case of stillbirth or perinatal asphyxia of unclear origin. In order to minimize the risk of recurrence in further pregnancies, elective cesarean section may be considered.

  10. A Mouse Model of Endocardial Fibroelastosis

    PubMed Central

    Clark, Elizabeth S.; Pepper, Victoria K.; Best, Cameron; Onwuka, Ekene; Yi, Tai; Tara, Shuhei; Cianciolo, Rachel; Baker, Peter; Shinoka, Toshiharu; Breuer, Christopher K.

    2015-01-01

    Background Endocardial Fibroelastosis (EFE) is a pathologic condition of abnormal deposition of collagen and elastin within the endocardium of the heart. It is seen in conjunction with a variety of diseases including hypoplastic left heart syndrome and viral endocarditis. While an experimental model using heterotopic heart transplant in rats has been described, we sought to fully describe a mouse model that can be used to further elucidate the potential mechanisms of and treatments for EFE. Materials and Methods The hearts of 2-day-old C57BL/6 mice were transplanted into the abdomen of 7-week-old C57BL/6 mice. At 2 weeks, the hearts were harvested and histologic analysis performed using hematoxylin and eosin, Masson’s Trichrome, Russell-Movat’s Pentachrome, Picrosirius Red, Hart’s, Verhoeff-Van Gieson, and Weigert’s Resorcin-Fuschin stains. Additionally, one heart was analysed using transmission electron microscopy (TEM). Results Specimens demonstrated abnormal accumulation of both collagen and elastin within the endocardium with occasional expansion in to the myocardium. Heterogeneity in extracellular matrix deposition was noted in the histologic specimens. In addition, TEM demonstrated the presence of excess collagen within the endocardium. Conclusions The heterotopic transplantation of an immature heart into a mouse results in changes consistent with EFE. This model is appropriate to investigate the etiology and treatment of endocardial fibroelastosis. PMID:26363814

  11. Complete endocardial cushion defects in pregnancy: a case report.

    PubMed

    Chen, Xiangjuan; Xiao, Biru; Yang, Weiyu; Chen, Yunqin; Zhang, Wenmiao; Zhu, Haiyan

    2014-03-10

    Complete endocardial cushion defect is a congenital heart disease characterized by a variable deficiency of the atrioventricular area in the developing heart. The mortality rate for an unrepaired endocardial cushion defect in pregnancy and the postpartum period is high. We present a rare case of a pregnant woman with complete endocardial cushion defect. A 20-year-old Chinese woman with unrepaired complete endocardial cushion defect delivered a premature male baby at 33 weeks and six days of pregnancy in our hospital. The baby had a normal human karyotype and a birth defect of hypospadias deformity. Our patient died from heart failure 10 minutes after delivery. She had severe pulmonary hypertension and suspected trisomy 21. Our experience further emphasizes the necessity of prenatal screening for congenital heart defects and of prompt surgical correction for endocardial cushion defects during infancy. Mortality for endocardial cushion defect during pregnancy and the postpartum period is high and women with complete endocardial cushion defect should avoid pregnancy, especially those women who cannot intellectually judge their risks.

  12. Effects of endocardial microwave energy ablation

    PubMed Central

    Climent, Vicente; Hurlé, Aquilino; Ho, Siew Yen; Sánchez-Quintana, Damián

    2005-01-01

    Until recently the treatment of atrial fibrillation (AF) consisted primarily of palliation, mostly in the form of pharmacological intervention. However because of recent advances in nonpharmacologic therapies, the current expectation of patients and referring physicians is that AF will be cured, rather than palliated. In recent years there has been a rapid expansion in the availability and variety of energy sources and devices for ablation. One of these energies, microwave, has been applied clinically only in the last few years, and may be a promising technique that is potentially capable of treating a wide range of ventricular and supraventricular arrhythmias. The purpose of this study was to review microwave energy ablation in surgical treatment of AF with special interest in histology and ultrastructure of lesions produced by this endocardial ablation procedure. PMID:16943871

  13. Effects of endocardial microwave energy ablation.

    PubMed

    Climent, Vicente; Hurlé, Aquilino; Ho, Siew Yen; Sánchez-Quintana, Damián

    2005-07-01

    Until recently the treatment of atrial fibrillation (AF) consisted primarily of palliation, mostly in the form of pharmacological intervention. However because of recent advances in nonpharmacologic therapies, the current expectation of patients and referring physicians is that AF will be cured, rather than palliated. In recent years there has been a rapid expansion in the availability and variety of energy sources and devices for ablation. One of these energies, microwave, has been applied clinically only in the last few years, and may be a promising technique that is potentially capable of treating a wide range of ventricular and supraventricular arrhythmias. The purpose of this study was to review microwave energy ablation in surgical treatment of AF with special interest in histology and ultrastructure of lesions produced by this endocardial ablation procedure.

  14. Localization of endocardial ectopic activity by means of noninvasive endocardial surface current density reconstruction

    NASA Astrophysics Data System (ADS)

    Lai, Dakun; Liu, Chenguang; Eggen, Michael D.; Iaizzo, Paul A.; He, Bin

    2011-07-01

    Localization of the source of cardiac ectopic activity has direct clinical benefits for determining the location of the corresponding ectopic focus. In this study, a recently developed current-density (CD)-based localization approach was experimentally evaluated in noninvasively localizing the origin of the cardiac ectopic activity from body-surface potential maps (BSPMs) in a well-controlled experimental setting. The cardiac ectopic activities were induced in four well-controlled intact pigs by single-site pacing at various sites within the left ventricle (LV). In each pacing study, the origin of the induced ectopic activity was localized by reconstructing the CD distribution on the endocardial surface of the LV from the measured BSPMs and compared with the estimated single moving dipole (SMD) solution and precise pacing site (PS). Over the 60 analyzed beats corresponding to ten pacing sites (six for each), the mean and standard deviation of the distance between the locations of maximum CD value and the corresponding PSs were 16.9 mm and 4.6 mm, respectively. In comparison, the averaged distance between the SMD locations and the corresponding PSs was slightly larger (18.4 ± 3.4 mm). The obtained CD distribution of activated sources extending from the stimulus site also showed high consistency with the endocardial potential maps estimated by a minimally invasive endocardial mapping system. The present experimental results suggest that the CD method is able to locate the approximate site of the origin of a cardiac ectopic activity, and that the distribution of the CD can portray the propagation of early activation of an ectopic beat.

  15. Endocardial electrogram characteristics of epicardial ventricular arrhythmias.

    PubMed

    Tzou, Wendy S; Nguyen, Duy T; Aleong, Ryan G; Varosy, Paul D; Katz, David F; Heath, Russell R; Schuller, Joseph L; Lowery, Christopher M; Lewkowiez, Laurent; Sauer, William H

    2013-06-01

    While most ventricular arrhythmias (VA) can be ablated successfully using an endocardial (endo) approach, epicardial (epi) mapping and ablation is sometimes required. There may be suggestive clues on the surface electrocardiogram; however, identification of an epi origin of VA with certainty remains problematic. All patients referred for ablation of ventricular tachycardia or frequent ventricular ectopy from June 2007 to July 2011 were evaluated. Patients with completed endo and epi electroanatomical activation maps of an epi VA were included (n = 10). Bipolar electrograms (EGMs) in the area of earliest endo activation were analyzed and compared to the area of early epi activation. An EGM component was characterized as far field if it was monophasic and there was inability to capture. We identified 3 characteristics from endo mapping that consistently indicated need for epi ablation: (1) Diffusely early activation (>2 cm(2) region of sites with equally earliest activation within 10 milliseconds). (2) Sequence of a far-field EGM followed by a near-field EGM in the region of earliest endo activation. (3) Inability to capture the far-field component of the earliest EGM (stim-QRS < egm-QRS time) or reproduce morphological features of the VA complex with stimulation at the earliest endo site of activation. The presence of a diffusely early area of activation and inability to capture a far-field endo EGM indicates that epi ablation may be needed to eliminate a VA. © 2013 Wiley Periodicals, Inc.

  16. Morphology of endocardial T-waves of fusion beats.

    PubMed

    Boute, W; Cals, G L; Den Heijer, P; Wittkampf, F H

    1988-11-01

    Recently developed stimulation techniques are capable of eliminating polarization afterpotentials caused by the emitted stimulus. A well-controlled study method was developed to initiate various degrees of fusion and to monitor changes in the morphology of the endocardial signal. The study was performed on two dogs. The zone during which fusion could be provoked was less than 30 ms in both dogs. In addition, the results show a significant decrease in the endocardial T-wave amplitude as soon as fusion was noticed, while the QT interval then slightly lengthened. Furthermore, the evoked R-wave duration shortened during fusion, while the stimulus to R-wave interval lengthened. These results have consequences for pacemakers that use evoked endocardial signal characteristics for driving a pacemaker function.

  17. Fibrillin-2b regulates endocardial morphogenesis in zebrafish.

    PubMed

    Mellman, Katharine; Huisken, Jan; Dinsmore, Colin; Hoppe, Cornelia; Stainier, Didier Y

    2012-12-01

    scotch tape (sco) is a zebrafish cardiac mutant initially proposed to exhibit a reduced amount of cardiac jelly, the extracellular matrix between the myocardial and endocardial layers. We analyzed sco(te382) mutant hearts in detail using both selective plane illumination microscopy (SPIM) and transmission electron microscopy (TEM), and observed a fascinating endocardial defect. Time-lapse SPIM imaging of wild-type and mutant embryos revealed significant and dynamic gaps between endocardial cells during development. Although these gaps close in wild-type animals, they fail to close in the mutants, ultimately leading to a near complete absence of endocardial cells in the atrial chamber by the heart looping stage. TEM analyses confirm the presence of gaps between endocardial cells in sco mutants, allowing the apparent leakage of cardiac jelly into the lumen. High-resolution mapping places the sco(te382) mutation within the fbn2b locus, which encodes the extracellular matrix protein Fibrillin 2b (OMIM ID: 121050). Complementation and further phenotypic analyses confirm that sco is allelic to puff daddy(gw1) (pfd(gw1)), a null mutant in fbn2b, and that sco(te382) is a hypomorphic allele of fbn2b. fbn2b belongs to a family of genes responsible for the assembly of microfibrils throughout development, and is essential for microfibril structural integrity. In sco(te382) mutants, Fbn2b is disabled by a missense mutation in a highly conserved cbEGF domain, which likely interferes with protein folding. Integrating data obtained from microscopy and molecular biology, we posit that this mutation impacts the rigidity of Fbn2b, imparting a structural defect that weakens endocardial adhesion thereby resulting in perforated endocardium.

  18. Epicardial/endocardial sinus node ablation after failed endocardial ablation for the treatment of inappropriate sinus tachycardia.

    PubMed

    Jacobson, Jason T; Kraus, Alexandria; Lee, Richard; Goldberger, Jeffrey J

    2014-03-01

    Success of endocardial sinus node (SN) ablation for refractory inappropriate sinus tachycardia (IST) is limited by the epicardial location of the SN and potential damage to the phrenic nerve (PN). An epicardial approach may overcome these limitations. IST patients who failed endocardial ablation underwent an epicardial approach. Percutaneous pericardial access was obtained with a double wire technique for PN protection (i.e., with a balloon catheter), if needed. Earliest sinus activation was mapped and ablated with remapping for changes in P-wave morphology or sinus rate. The endpoint was total SN ablation (patients with atrial pacing [AP]); otherwise the target was a >25% decrease in sinus rate and inversion of P-wave axis. Five patients (all female, age 36 ± 4 years) underwent ablation. Two had prior AP, and 1 elected to have SN ablation and pacemaker during the same procedure. Three had prior endocardial ablation limited by PN proximity. Baseline sinus rate was 119 ± 20 bpm. After 35.2 ± 21.3 lesions (22.4 ± 21.7 epicardial, 12.8 ± 21.3 endocardial), 4 were in junctional rhythm, 1 in atrial rhythm at 90 bpm. This latter patient had symptom recurrence and underwent combined minimally invasive surgical/catheter SN cryoablation. Atrial tachycardia subsequently occurred and was successfully ablated. The only significant complication was pericarditis (3 patients). At last follow-up (30.4 ± 18.4 months), all had symptom resolution. Two were AP >99%, 1 was AP 54%. Two remain in ectopic atrial rhythm with controlled rates. Combined epicardial/endocardial SN ablation is a viable approach for patients with severely symptomatic IST after a failed endocardial attempt. © 2013 Wiley Periodicals, Inc.

  19. Transvenous extraction of an abandoned endocardial pacemaker lead in a dog.

    PubMed

    LeBlanc, Nicole; Scollan, Katherine; Sisson, David

    2014-03-01

    A 6-year-old male castrated labrador retriever presented with endocardial pacemaker infection following migration and subsequent repositioning of the pulse generator. An epicardial lead and pulse generator were surgically implanted and the endocardial lead could not be removed with manual traction. The endocardial lead was severed, anchored, and abandoned at the thoracic inlet. The patient presented 4 months later with endocardial lead migration, bacteremia, and suspected glomerulonephritis. The endocardial pacemaker lead was transvenously extracted using a mechanical dilator sheath and locking stylet. This report of transvenous pacemaker lead extraction in a dog addresses the challenges and describes recent advances in extraction devices.

  20. Endocardial Endothelial Dysfunction Progressively Disrupts Initially Anti then Pro-Thrombotic Pathways in Heart Failure Mice

    PubMed Central

    Schoner, Amanda; Tyrrell, Christina; Wu, Melinda; Gelow, Jill M.; Hayes, Alicia A.; Lindner, Jonathan R.; Thornburg, Kent L.; Hasan, Wohaib

    2015-01-01

    Objective An experimental model of endocardial thrombosis has not been developed and endocardial endothelial dysfunction in heart failure (HF) is understudied. We sought to determine whether disruption of the endothelial anti-coagulant activated protein C (APC) pathway in CREBA133 HF mice promotes endocardial thrombosis in the acute decompensated phase of the disease, and whether alterations in von Willebrand factor (vWF) secretion from HF endocardium reduces thrombus formation as HF stabilizes. Approach and results Echocardiography was used to follow HF development and to detect endocardial thrombi in CREBA133 mice. Endocardial thrombi incidence was confirmed with immunohistochemistry and histology. In early and acute decompensated phases of HF, CREBA133 mice had the highest incidence of endocardial thrombi and these mice also had a shorter tail-bleeding index consistent with a pro-thrombotic milieu. Both APC generation, and expression of receptors that promote APC function (thrombomodulin, endothelial protein C receptor, protein S), were suppressed in the endocardium of acute decompensated HF mice. However, in stable compensated HF mice, an attenuation occurred for vWF protein content and secretion from endocardial endothelial cells, vWF-dependent platelet agglutination (by ristocetin), and thrombin generation on the endocardial surface. Conclusions CREBA133 mice develop HF and endocardial endothelial dysfunction. Attenuation of the anti-coagulant APC pathway promotes endocardial thrombosis in early and acute decompensated phases of HF. However, in stable compensated HF mice, disruptions in endothelial vWF expression and extrusion may actually reduce the incidence of endocardial thrombosis. PMID:26565707

  1. Endocardial left ventricular pacing after accidental aortic wall perforation.

    PubMed

    Şoşdean, Raluca; Enache, Bogdan; Macarie, Răzvan Ioan; Pescariu, Sorin

    2016-03-01

    Inadvertent endocardial placement of a pacing lead in the left ventricle through the aortic valve is a rare complication with an unknown incidence because of inadequate reporting. Reported cases are usually the result of lead insertion via the subclavian artery. A possible but very unusual situation is endocardial lead insertion in the left ventricle after aortic arch perforation. We report the case of a 72-year-old woman in whom a screw-in pacing lead accidentally perforated the aortic arch and continued its way through the ascending aorta, aortic valve and left ventricle, after insertion through the left subclavian vein. We describe how this complication was diagnosed, the predisposing factors, the risks it carries and the ways in which devastating consequences have so far been avoided, as the patient refused any surgical intervention including lead removal. Copyright © 2016. Published by Elsevier España.

  2. Nfatc1 directs the endocardial progenitor cells to make heart valve primordium.

    PubMed

    Wu, Bingruo; Baldwin, H Scott; Zhou, Bin

    2013-11-01

    Heart valves arise from the cardiac endocardial cushions located at the atrioventricular canal (AVC) and cardiac outflow tract (OFT) during development. A subpopulation of cushion endocardial cells undergoes endocardial to mesenchymal transformation (EMT) and generates the cushion mesenchyme, which is then remodeled into the interstitial tissue of the mature valves. The cushion endocardial cells that do not undertake EMT proliferate to elongate valve leaflets. During EMT and the post-EMT valve remodeling, endocardial cells at the cushions highly express nuclear factor in activated T cell, cytoplasmic 1 (Nfatc1), a transcription factor required for valve formation in mice. In this review, we present the current knowledge of Nfatc1 roles in the ontogeny of heart valves with a focus on the fate decision of the endocardial cells in the processes of EMT and valve remodeling. © 2013 Elsevier Inc. All rights reserved.

  3. Circumferential distortion modeling of the TF30-P-3 compression system

    NASA Technical Reports Server (NTRS)

    Mazzawy, R. S.; Banks, G. A.

    1977-01-01

    Circumferential inlet pressure and temperature distortion testing of the TF30 P-3 turbofan engine was conducted. The compressor system at the test conditions run was modelled according to a multiple segment parallel compressor model. Aspects of engine operation and distortion configuration modelled include the effects of compressor bleeds, relative pressure-temperature distortion alignment and circumferential distortion extent. Model predictions for limiting distortion amplitudes and flow distributions within the compression system were compared with test results in order to evaluate predicted trends. Relatively good agreement was obtained. The model also identified the low pressure compressor as the stall-initiating component, which was in agreement with the data.

  4. Spatial Transcriptional Profile of the Chick and Mouse Endocardial Cushions Identify Novel Regulators of Endocardial EMT in vitro

    PubMed Central

    DeLaughter, Daniel M.; Christodoulou, Danos C.; Robinson, Jamille Y.; Seidman, Christine E.; Baldwin, H. Scott; Seidman, J. G.; Barnett, Joey V.

    2013-01-01

    Valvular Interstitial Cells (VICs) are a common substrate for congenital and adult heart disease yet the signaling mechanisms governing their formation during early valvulogenesis are incompletely understood. We developed an unbiased strategy to identify genes important in endocardial epithelial-to-mesenchymal transformation (EMT) using a spatial transcriptional profile. Endocardial cells overlaying the cushions of the atrioventricular canal (AVC) and outflow tract (OFT) undergo an EMT to yield VICs. RNA sequencing (RNA-seq) analysis of gene expression between AVC, OFT, and ventricles (VEN) isolated from chick and mouse embryos at comparable stages of development (chick HH18; mouse E11.0) was performed. EMT occurs in the AVC and OFT cushions, but not VEN at this time. 198 genes in the chick (n=1) and 105 genes in the mouse (n=2) were enriched 2-fold in the cushions. Gene regulatory networks (GRN) generated from cushion-enriched gene lists confirmed TGFβ as a nodal point and identified NF-κB as a potential node. To reveal previously unrecognized regulators of EMT four candidate genes, Hapln1, Id1, Foxp2, and Meis2, and a candidate pathway, NF-κB, were selected. In vivo spatial expression of each gene was confirmed by in situ hybridization and a functional role for each in endocardial EMT was determined by siRNA knockdown in a collagen gel assay. Our spatial-transcriptional profiling strategy yielded gene lists which reflected the known biology of the system. Further analysis accurately identified and validated previously unrecognized novel candidate genes and the NF-κB pathway as regulators of endocardial cell EMT in vitro. PMID:23557753

  5. Correlation between longitudinal, circumferential, and radial moduli in cortical bone: effect of mineral content.

    PubMed

    Macione, J; Depaula, C A; Guzelsu, N; Kotha, S P

    2010-07-01

    Previous studies indicate that changes in the longitudinal elastic properties of bone due to changes in mineral content are related to the longitudinal strength of bone tissue. Changes in mineral content are expected to affect bone tissue mechanical properties along all directions, albeit to different extents. However, changes in tissue mechanical properties along the different directions are expected to be correlated to one another. In this study, we investigate if radial, circumferential, and longitudinal moduli are related in bone tissue with varying mineral content. Plexiform bovine femoral bone samples were treated in fluoride ion solutions for a period of 3 and 12 days to obtain bones with 20% and 32% lower effective mineral contents. Transmission ultrasound velocities were obtained in the radial, circumferential, and longitudinal axes of bone and combined with measured densities to obtain corresponding tensorial moduli. Results indicate that moduli decreased with fluoride ion treatments and were significantly correlated to one another (r(2) radial vs. longitudinal = 0.80, r(2) circumferential vs. longitudinal = 0.90, r(2) radial vs. circumferential = 0.85). Densities calculated from using ultrasound parameters, acoustic impedance and transmission velocities, were moderately correlated to those measured by the Archimedes principle (r(2)=0.54, p<0.01). These results suggest that radial and circumferential ultrasound measurements could be used to determine the longitudinal properties of bone and that ultrasound may not be able to predict in vitro densities of bones containing unbonded mineral. Published by Elsevier Ltd.

  6. Effects of halothane on action potential configuration in sub-endocardial and sub-epicardial myocytes from normotensive and hypertensive rat left ventricle.

    PubMed

    Rithalia, A; Hopkins, P M; Harrison, S M

    2003-04-01

    Halothane shortens ventricular action potential duration (APD), as a consequence of its inhibitory effects on a variety of membrane currents, an effect that is greater in sub-endocardial than sub-epicardial myocytes. In hypertrophied ventricle, APD is prolonged as a consequence of electrical remodelling. In this study, we compared the effects of halothane on transmural APD in myocytes from normal and hypertrophied ventricle. Myocytes were isolated from the sub-endocardium and sub-epicardium of the left ventricle of spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats. Action potentials were recorded before, during, and after a 1-min exposure to 0.6 mM halothane and APD measured from the peak of the action potential to repolarization at -50 mV (APD(-50 mV)). Data are presented as mean (SEM). In WKY myocytes, halothane reduced APD(-50 mV) from 21 (2) to 18 (2) ms (P<0.001, n=15) in sub-epicardial myocytes but abbreviated APD(-50 mV) to a greater extent in sub-endocardial myocytes (37 (4) to 28 (3) ms; P<0.001, n=14). In SHR myocytes, APD(-50 mV) values were prolonged compared with WKY and APD(-50 mV) was reduced by halothane from 36 (6) to 27 (4) ms (P<0.016) and from 77 (10) to 38 (4) ms (P<0.001) in sub-epicardial and sub-endocardial myocytes, respectively. In the SHR, hypertrophic remodelling was not homogeneous; APD(-50 mV) was prolonged to a greater extent in sub-endocardial than sub-epicardial cells. Halothane reduced APD to a greater extent in sub-endocardium than sub-epicardium in both WKY and SHR but this effect was larger proportionately in SHR myocytes. The transmural gradient of repolarization was reduced in WKY and effectively abolished in SHR by halothane, which might disturb normal ventricular repolarization.

  7. Circumferential cracking of steam generator tubes

    SciTech Connect

    Karwoski, K.J.

    1997-04-01

    On April 28, 1995, the U.S. Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 95-03, {open_quote}Circumferential Cracking of Steam Generator Tubes.{close_quote} GL 95-03 was issued to obtain information needed to verify licensee compliance with existing regulatory requirements regarding the integrity of steam generator tubes in domestic pressurized-water reactors (PWRs). This report briefly describes the design and function of domestic steam generators and summarizes the staff`s assessment of the responses to GL 95-03. The report concludes with several observations related to steam generator operating experience. This report is intended to be representative of significant operating experience pertaining to circumferential cracking of steam generator tubes from April 1995 through December 1996. Operating experience prior to April 1995 is discussed throughout the report, as necessary, for completeness.

  8. Guided Circumferential Waves in Layered Poroelastic Cylinders

    NASA Astrophysics Data System (ADS)

    Shah, S. A.; Apsar, G.

    2016-12-01

    The present paper investigates the propagation of time harmonic circumferential waves in a two-dimensional hollow poroelastic cylinder with an inner shaft (shaft-bearing assembly). The hollow poroelastic cylinder and inner shaft are assumed to be infinite in axial direction. The outer surface of the cylinder is stress free and at the interface, between the inner shaft and the outer cylinder, it is assumed to be free sliding and the interfacial shear stresses are zero, also the normal stress and radial displacements are continuous. The frequency equation of guided circumferential waves for a permeable and an impermeable surface is obtained. When the angular wave number vanish the frequency equation of guided circumferential waves for a permeable and an impermeable surface degenerates and the dilatational and shear waves are uncoupled. Shear waves are independent of the nature of surface. The frequency equation of a permeable and an impermeable surface for bore-piston assembly is obtained as a particular case of the model under consideration when the outer radius of the hollow poroelastic cylinder tends to infinity. Results of previous studies are obtained as a particular case of the present study. Nondimensional frequency as a function of wave number is presented graphically for two types of models and discussed. Numerical results show that, in general, the first modes are linear for permeable and impermeable surfaces and the frequency of a permeable surface is more than that of an impermeable surface.

  9. Endocardial fibrosarcoma in a reticulated python (Python reticularis).

    PubMed

    Gumber, Sanjeev; Nevarez, Javier G; Cho, Doo-Youn

    2010-11-01

    A female, reticulated python (Python reticularis) of unknown age was presented with a history of lethargy, weakness, and distended coelom. Physical examination revealed severe dystocia and stomatitis. The reticulated python was euthanized due to a poor clinical prognosis. Postmortem examination revealed marked distention of the reproductive tract with 26 eggs (10-12 cm in diameter), pericardial effusion, and a slightly firm, pale tan mass (3-4 cm in diameter) adhered to the endocardium at the base of aorta. Based on histopathologic and transmission electron microscopic findings, the diagnosis of endocardial fibrosarcoma was made.

  10. In vivo measurement of swine endocardial convective heat transfer coefficient.

    PubMed

    Tangwongsan, Chanchana; Will, James A; Webster, John G; Meredith, Kenneth L; Mahvi, David M

    2004-08-01

    We measured the endocardial convective heat transfer coefficient h at 22 locations in the cardiac chambers of 15 pigs in vivo. A thin-film Pt catheter tip sensor in a Wheatstone-bridge circuit, similar to a hot wire/film anemometer, measured h. Using fluoroscopy, we could precisely locate the steerable catheter sensor tip and sensor orientation in pigs' cardiac chambers. With flows, h varies from 2500 to 9500 W/m2 x K. With zero flow, h is approximately 2400 W/m2 x K. These values of h can be used for the finite element method modeling of radiofrequency cardiac catheter ablation.

  11. Twist1 function in endocardial cushion cell proliferation, migration, and differentiation during heart valve development.

    PubMed

    Shelton, Elaine L; Yutzey, Katherine E

    2008-05-01

    Twist1 is a bHLH transcription factor that regulates cell proliferation, migration, and differentiation in embryonic progenitor cell populations and transformed tumor cells. While much is known about Twist1's function in a variety of mesenchymal cell types, the role of Twist1 in endocardial cushion cells is unknown. Twist1 gain and loss of function experiments were performed in primary chicken endocardial cushion cells in order to elucidate its role in endocardial cushion development. These studies indicate that Twist1 can induce endocardial cushion cell proliferation as well as promote endocardial cushion cell migration. Furthermore, Twist1 is subject to BMP regulation and can induce expression of cell migration marker genes including Periostin, Cadherin 11, and Mmp2 while repressing markers of valve cell differentiation including Aggrecan. Previously, Tbx20 has been implicated in endocardial cushion cell proliferation and differentiation, and in the current study, Tbx20 also promotes cushion cell migration. Twist1 can induce Tbx20 expression, while Tbx20 does not affect Twist1 expression. Taken together, these data indicate a role for Twist1 upstream of Tbx20 in promoting cell proliferation and migration and repressing differentiation in endocardial cushion cells during embryonic development.

  12. Mechanisms of circumferential gyral convolution in primate brains.

    PubMed

    Zhang, Tuo; Razavi, Mir Jalil; Chen, Hanbo; Li, Yujie; Li, Xiao; Li, Longchuan; Guo, Lei; Hu, Xiaoping; Liu, Tianming; Wang, Xianqiao

    2017-06-01

    Mammalian cerebral cortices are characterized by elaborate convolutions. Radial convolutions exhibit homology across primate species and generally are easily identified in individuals of the same species. In contrast, circumferential convolutions vary across species as well as individuals of the same species. However, systematic study of circumferential convolution patterns is lacking. To address this issue, we utilized structural MRI (sMRI) and diffusion MRI (dMRI) data from primate brains. We quantified cortical thickness and circumferential convolutions on gyral banks in relation to axonal pathways and density along the gray matter/white matter boundaries. Based on these observations, we performed a series of computational simulations. Results demonstrated that the interplay of heterogeneous cortex growth and mechanical forces along axons plays a vital role in the regulation of circumferential convolutions. In contrast, gyral geometry controls the complexity of circumferential convolutions. These findings offer insight into the mystery of circumferential convolutions in primate brains.

  13. View of exterior circumferential path at northeast side of building ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of exterior circumferential path at northeast side of building beneath trellis, looking southeast - National Zoological Park, Bird House, 3001 Connecticut Avenue NW, Washington, District of Columbia, DC

  14. 49 CFR 178.345-7 - Circumferential reinforcements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... tank heads. (1) Circumferential reinforcement must be located so that the thickness and tensile strength of the shell material in combination with the frame and reinforcement produces structural...

  15. 49 CFR 178.345-7 - Circumferential reinforcements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... tank heads. (1) Circumferential reinforcement must be located so that the thickness and tensile strength of the shell material in combination with the frame and reinforcement produces structural...

  16. 49 CFR 178.345-7 - Circumferential reinforcements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... tank heads. (1) Circumferential reinforcement must be located so that the thickness and tensile strength of the shell material in combination with the frame and reinforcement produces structural...

  17. 49 CFR 178.345-7 - Circumferential reinforcements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... tank heads. (1) Circumferential reinforcement must be located so that the thickness and tensile strength of the shell material in combination with the frame and reinforcement produces structural...

  18. Multiple endocardial neurofibromas in a rosy-billed pochard (Netta peposaca)

    PubMed Central

    Miller, Andrew D.; Baitchman, Eric J.; Masek-Hammerman, Katherine

    2013-01-01

    Endocardial neoplasms are uncommon in veterinary species with most cases restricted to endocardial schwannomas in aged rats. A 15-year-old, male rosy-billed pochard (Netta peposaca) was diagnosed following necropsy with numerous, proliferative endocardial masses. Histologically, these masses were composed of interlacing streams and bundles of neoplastic spindle cells supported by a fine fibrovascular stroma. Rare areas of cellular and nuclear palisading were present in the nodules. Approximately 60% of the neoplastic cells were strongly positive for S-100, whereas none of the neoplastic cells was positive for desmin, synaptophysin, neurofilament, and glial fibrillary acidic protein. The histologic features coupled with the S-100 immunoreactivity led to a diagnosis of endocardial neurofibroma. PMID:22362538

  19. Axial-Loading Circumferential Dovetail Turbine-Blade Mount

    NASA Technical Reports Server (NTRS)

    Pierce, Martin J.; Ward, Steven D.; Eskridge, Ronald R.

    1992-01-01

    In new configuration, retaining ring holds base of blades in circumferential dovetail slot. Blades inserted axially via loading slots into circumferential dovetail slot. Ring placed over loading slots and fastened with split ring held by arm of disk. Blades less likely to be shaken loose during operation.

  20. Probing chromatin landscape reveals roles of endocardial TBX20 in septation

    PubMed Central

    Boogerd, Cornelis J.; Aneas, Ivy; Sakabe, Noboru; Dirschinger, Ralph J.; Cheng, Quen J.; Chen, Ju; Nobrega, Marcelo A.; Evans, Sylvia M.

    2016-01-01

    Mutations in the T-box transcription factor TBX20 are associated with multiple forms of congenital heart defects, including cardiac septal abnormalities, but our understanding of the contributions of endocardial TBX20 to heart development remains incomplete. Here, we investigated how TBX20 interacts with endocardial gene networks to drive the mesenchymal and myocardial movements that are essential for outflow tract and atrioventricular septation. Selective ablation of Tbx20 in murine endocardial lineages reduced the expression of extracellular matrix and cell migration genes that are critical for septation. Using the assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq), we identified accessible chromatin within endocardial lineages and intersected these data with TBX20 ChIP-seq and chromatin loop maps to determine that TBX20 binds a conserved long-range enhancer to regulate versican (Vcan) expression. We also observed reduced Vcan expression in Tbx20-deficient mice, supporting a direct role for TBX20 in Vcan regulation. Further, we show that the Vcan enhancer drove reporter gene expression in endocardial lineages in a TBX20–binding site–dependent manner. This work illuminates gene networks that interact with TBX20 to orchestrate cardiac septation and provides insight into the chromatin landscape of endocardial lineages during septation. PMID:27348591

  1. The effect of circumferential distortion on fan performance at two levels of blade loading

    NASA Technical Reports Server (NTRS)

    Hartmann, M. J.; Sanger, N. L.

    1975-01-01

    Single stage fans designed for two levels of pressure ratio or blade loading were subjected to screen-induced circumferential distortions of 90-degree extent. Both fan rotors were designed for a blade tip speed of 425 m/sec, blade solidity of 1.3 and a hub-to-tip radius ratio of 0.5. Circumferential measurements of total pressure, temperature, static pressure, and flow angle were obtained at the hub, mean and tip radii at five axial stations. Rotor loading level did not appear to have a significant influence on rotor response to distorted flow. Losses in overall pressure ratio due to distortion were most severe in the stator hub region of the more highly loaded stage. At the near stall operating condition tip and hub regions of (either) rotor demonstrated different response characteristics to the distorted flow. No effect of loading was apparent on interactions between rotor and upstream distorted flow fields.

  2. Genetic interaction between pku300 and fbn2b controls endocardial cell proliferation and valve development in zebrafish.

    PubMed

    Wang, Xu; Yu, Qingming; Wu, Qing; Bu, Ye; Chang, Nan-Nan; Yan, Shouyu; Zhou, Xiao-Hai; Zhu, Xiaojun; Xiong, Jing-Wei

    2013-03-15

    Abnormal cardiac valve morphogenesis is a common cause of human congenital heart disease. The molecular mechanisms regulating endocardial cell proliferation and differentiation into cardiac valves remain largely unknown, although great progress has been made on the endocardial contribution to the atrioventricular cushion and valve formation. We found that scotch tape(te382) (sco(te382)) encodes a novel transmembrane protein that is crucial for endocardial cell proliferation and heart valve development. The zebrafish sco(te382) mutant showed diminished endocardial cell proliferation, lack of heart valve leaflets and abnormal common cardinal and caudal veins. Positional cloning revealed a C946T nonsense mutation of a novel gene pku300 in the sco(te382) locus, which encoded a 540-amino-acid protein on cell membranes with one putative transmembrane domain and three IgG domains. A known G3935T missense mutation of fbn2b was also found ∼570 kb away from pku300 in sco(te382) mutants. The genetic mutant sco(pku300), derived from sco(te382), only had the C946T mutation of pku300 and showed reduced numbers of atrial endocardial cells and an abnormal common cardinal vein. Morpholino knockdown of fbn2b led to fewer atrial endocardial cells and an abnormal caudal vein. Knockdown of both pku300 and fbn2b phenocopied these phenotypes in sco(te382) genetic mutants. pku300 transgenic expression in endocardial and endothelial cells, but not myocardial cells, partially rescued the atrial endocardial defects in sco(te382) mutants. Mechanistically, pku300 and fbn2b were required for endocardial cell proliferation, endocardial Notch signaling and the proper formation of endocardial cell adhesion and tight junctions, all of which are crucial for cardiac valve development. We conclude that pku300 and fbn2b represent the few genes capable of regulating endocardial cell proliferation and signaling in zebrafish cardiac valve development.

  3. Metal Ir coatings on endocardial electrode tips, obtained by MOCVD

    NASA Astrophysics Data System (ADS)

    Vikulova, Evgeniia S.; Kal'nyi, Danila B.; Shubin, Yury V.; Kokovkin, Vasily V.; Morozova, Natalya B.; Hassan, Aseel; Basova, Tamara V.

    2017-12-01

    The present work demonstrates the application of the Metal-Organic Chemical Vapor Deposition technique to fabricate metal iridium coatings onto the pole tips of endocardial electrodes. Using iridium (III) acetylacetonate as a volatile precursor, the target coatings were successfully applied to the working surface of cathodes and anodes of pacemaker electrodes in the flow type reactor in hydrogen atmosphere at deposition temperature of 550 °C. The coating samples were characterized by means of XRD, SEM, Raman- and XPS-spectroscopies. The formation of non-textured coatings with fractal-like morphology and 7-24 nm crystallite size has been realized. The electrochemical properties of the coatings were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The charge storage capacity values of the electrochemically activated samples were 17.0-115 mC cm-2 and 14.4-76.5 mC cm-2 for measurements carried out in 0.1 M sulfuric acid and in phosphate buffer saline solutions, respectively. A comparison of some characteristics of the samples obtained with commercially available cathode of pacemaker electrodes is also presented.

  4. CIRCUMFERENTIAL MFL IN-LINE INSPECTION FOR CRACKS IN PIPELINES

    SciTech Connect

    J.B. Nestleroth

    2003-06-01

    Circumferential MFL is a new implementation of a widely used technology that has potential to provide improved detection and quantification of axially oriented defects such as cracks, seam weld defects, mechanical damage, and groove corrosion. This implementation works by orienting the magnetic field around the pipe rather that along the axis. By orienting the magnetic field around the pipe (the circumferential direction), the axial defects that were magnetically transparent can disrupt more of the magnetic field and can be more easily detected. Initial implementations of circumferential MFL have found that flux leakage from cracks at the interior of the pipe is small, and the signals from cracks are difficult to detect. The objective of this project is to improve detection of cracks by changing the implementation along with using data from overlapping and complementary inspection techniques. Two technology enhancements were investigated: Combining high- and low-magnetization technology for stress detection; and Combining axial and circumferential MFL methods. Although a method combining high- and low-magnetization technology showed promise for characterizing gouges cause by third party excavation equipment, its commercial development was not successful for two reasons. First, the stress diminishes the crack signal, while the opening of the crack increases the signal. The stress-induced changes in flux leakage around cracks were small and any critical information on the severity of cracks and crack-like defects is difficult to distinguish from changes caused by the crack opening and other inspection variables. Second, it is difficult to magnetize pipe material in the circumferential direction. A relatively low, non-uniform magnetization level produced by the circumferential magnetizer makes detection of changes due to stress extremely difficult. This project also examined combining axial and circumferential MFL to improve crack detection and distinguish cracks for

  5. Simultaneous Epicardial and Noncontact Endocardial Mapping of the Canine Right Atrium: Simulation and Experiment

    PubMed Central

    Sabouri, Sepideh; Matene, Elhacene; Vinet, Alain; Richer, Louis-Philippe; Cardinal, René; Armour, J. Andrew; Pagé, Pierre; Kus, Teresa; Jacquemet, Vincent

    2014-01-01

    Epicardial high-density electrical mapping is a well-established experimental instrument to monitor in vivo the activity of the atria in response to modulations of the autonomic nervous system in sinus rhythm. In regions that are not accessible by epicardial mapping, noncontact endocardial mapping performed through a balloon catheter may provide a more comprehensive description of atrial activity. We developed a computer model of the canine right atrium to compare epicardial and noncontact endocardial mapping. The model was derived from an experiment in which electroanatomical reconstruction, epicardial mapping (103 electrodes), noncontact endocardial mapping (2048 virtual electrodes computed from a 64-channel balloon catheter), and direct-contact endocardial catheter recordings were simultaneously performed in a dog. The recording system was simulated in the computer model. For simulations and experiments (after atrio-ventricular node suppression), activation maps were computed during sinus rhythm. Repolarization was assessed by measuring the area under the atrial T wave (ATa), a marker of repolarization gradients. Results showed an epicardial-endocardial correlation coefficients of 0.80 and 0.63 (two dog experiments) and 0.96 (simulation) between activation times, and a correlation coefficients of 0.57 and 0.46 (two dog experiments) and 0.92 (simulation) between ATa values. Despite distance (balloon-atrial wall) and dimension reduction (64 electrodes), some information about atrial repolarization remained present in noncontact signals. PMID:24598778

  6. Endocardial Brg1 disruption illustrates the developmental origins of semilunar valve disease.

    PubMed

    Akerberg, Brynn N; Sarangam, Maithri L; Stankunas, Kryn

    2015-11-01

    The formation of intricately organized aortic and pulmonic valves from primitive endocardial cushions of the outflow tract is a remarkable accomplishment of embryonic development. While not always initially pathologic, developmental semilunar valve (SLV) defects, including bicuspid aortic valve, frequently progress to a disease state in adults requiring valve replacement surgery. Disrupted embryonic growth, differentiation, and patterning events that "trigger" SLV disease are coordinated by gene expression changes in endocardial, myocardial, and cushion mesenchymal cells. We explored roles of chromatin regulation in valve gene regulatory networks by conditional inactivation of the Brg1-associated factor (BAF) chromatin remodeling complex in the endocardial lineage. Endocardial Brg1-deficient mouse embryos develop thickened and disorganized SLV cusps that frequently become bicuspid and myxomatous, including in surviving adults. These SLV disease-like phenotypes originate from deficient endocardial-to-mesenchymal transformation (EMT) in the proximal outflow tract (pOFT) cushions. The missing cells are replaced by compensating neural crest or other non-EMT-derived mesenchyme. However, these cells are incompetent to fully pattern the valve interstitium into distinct regions with specialized extracellular matrices. Transcriptomics reveal genes that may promote growth and patterning of SLVs and/or serve as disease-state biomarkers. Mechanistic studies of SLV disease genes should distinguish between disease origins and progression; the latter may reflect secondary responses to a disrupted developmental system.

  7. Common pathways regulate Type III TGFβ receptor-dependent cell invasion in epicardial and endocardial cells.

    PubMed

    Clark, Cynthia R; Robinson, Jamille Y; Sanchez, Nora S; Townsend, Todd A; Arrieta, Julian A; Merryman, W David; Trykall, David Z; Olivey, Harold E; Hong, Charles C; Barnett, Joey V

    2016-06-01

    Epithelial-Mesenchymal Transformation (EMT) and the subsequent invasion of epicardial and endocardial cells during cardiac development is critical to the development of the coronary vessels and heart valves. The transformed cells give rise to cardiac fibroblasts and vascular smooth muscle cells or valvular interstitial cells, respectively. The Type III Transforming Growth Factor β (TGFβR3) receptor regulates EMT and cell invasion in both cell types, but the signaling mechanisms downstream of TGFβR3 are not well understood. Here we use epicardial and endocardial cells in in vitro cell invasion assays to identify common mechanisms downstream of TGFβR3 that regulate cell invasion. Inhibition of NF-κB activity blocked cell invasion in epicardial and endocardial cells. NF-κB signaling was found to be dysregulated in Tgfbr3(-/-) epicardial cells which also show impaired cell invasion in response to ligand. TGFβR3-dependent cell invasion is also dependent upon Activin Receptor-Like Kinase (ALK) 2, ALK3, and ALK5 activity. A TGFβR3 mutant that contains a threonine to alanine substitution at residue 841 (TGFβR3-T841A) induces ligand-independent cell invasion in both epicardial and endocardial cells in vitro. These findings reveal a role for NF-κB signaling in the regulation of epicardial and endocardial cell invasion and identify a mutation in TGFβR3 which stimulates ligand-independent signaling.

  8. Hybrid approach to atrial fibrillation ablation using bipolar radiofrequency devices epicardially and cryoballoon endocardially.

    PubMed

    Kumar, Narendra; Pison, Laurent; La Meir, Mark; Maessen, Jos; Crijns, Harry J

    2014-10-01

    Bipolar radiofrequency (RF) devices are used epicardially by cardiac surgeons and cryoballoon endocardially by cardiac electrophysiologists for atrial fibrillation (AF) ablation, but in separate entities. The study's objective was to evaluate the feasibility and safety of combining an endocardial cryoballoon with epicardial bipolar RF ablation for the treatment of AF. A cohort of 7 patients with AF underwent a hybrid thoracoscopic surgical and endocardial ablation. To prevent bilateral sequential lung deflation in these patients with severe chronic obstructive pulmonary disease, the right pulmonary veins (PVs) were isolated using an epicardial bipolar RF clamp and the contralateral veins with an endocardial cryoballoon. A box lesion set was made epicardially using a bipolar RF pen. Acutely, pacing manoeuvres proved a bidirectional block in all PVs in all patients. No complications were seen. A box lesion was made in 5 patients. During follow-up, 2 of them had AF recurrence: 1 was treated successfully with sotalol and another underwent redo RF catheter ablation with reisolation of the right inferior PV. At present, 6 of 7 patients are in sinus rhythm without any anti-arrythmic drugs during a follow-up of more than 40 ± 3 months. A hybrid approach to AF ablation using a cryoballoon endocardially and a bipolar RF device epicardially is feasible and safe. © The Author 2014. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

  9. Simultaneous epicardial and noncontact endocardial mapping of the canine right atrium: simulation and experiment.

    PubMed

    Sabouri, Sepideh; Matene, Elhacene; Vinet, Alain; Richer, Louis-Philippe; Cardinal, René; Armour, J Andrew; Pagé, Pierre; Kus, Teresa; Jacquemet, Vincent

    2014-01-01

    Epicardial high-density electrical mapping is a well-established experimental instrument to monitor in vivo the activity of the atria in response to modulations of the autonomic nervous system in sinus rhythm. In regions that are not accessible by epicardial mapping, noncontact endocardial mapping performed through a balloon catheter may provide a more comprehensive description of atrial activity. We developed a computer model of the canine right atrium to compare epicardial and noncontact endocardial mapping. The model was derived from an experiment in which electroanatomical reconstruction, epicardial mapping (103 electrodes), noncontact endocardial mapping (2048 virtual electrodes computed from a 64-channel balloon catheter), and direct-contact endocardial catheter recordings were simultaneously performed in a dog. The recording system was simulated in the computer model. For simulations and experiments (after atrio-ventricular node suppression), activation maps were computed during sinus rhythm. Repolarization was assessed by measuring the area under the atrial T wave (ATa), a marker of repolarization gradients. Results showed an epicardial-endocardial correlation coefficients of 0.80 and 0.63 (two dog experiments) and 0.96 (simulation) between activation times, and a correlation coefficients of 0.57 and 0.46 (two dog experiments) and 0.92 (simulation) between ATa values. Despite distance (balloon-atrial wall) and dimension reduction (64 electrodes), some information about atrial repolarization remained present in noncontact signals.

  10. View of exterior circumferential path at northwest side of building, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of exterior circumferential path at northwest side of building, looking east toward building entrance - National Zoological Park, Bird House, 3001 Connecticut Avenue NW, Washington, District of Columbia, DC

  11. 49 CFR 178.345-7 - Circumferential reinforcements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...) Except for doubler plates and knuckle pads, no reinforcement may cover any circumferential joint. (c... from the applicable formula: I/C = 0.00027WL, for MS, HSLA and SS; or I/C = 0.000467WL, for...

  12. Noninvasive epicardial and endocardial mapping of premature ventricular contractions

    PubMed Central

    Revishvili, Amiran; Metzner, Andreas; Tsyganov, Alexey; Kalinin, Vitaly; Lemes, Christine; Saguner, Ardan M.; Maurer, Tilman; Deiss, Sebastian; Sopov, Oleg; Labarkava, Eugene; Chmelevsky, Mikhail; Kuck, Karl-Heinz

    2017-01-01

    Aims The aim of the present study was to estimate the accuracy of a novel non-invasive epicardial and endocardial electrophysiology system (NEEES) for mapping ectopic ventricular depolarizations. Methods and results The study enrolled 20 patients with monomorphic premature ventricular contractions (PVCs) or ventricular tachycardia (VT). All patients underwent pre-procedural computed tomography or magnetic resonance imaging of the heart and torso. Radiographic data were semi-automatically processed by the NEEES to reconstruct a realistic 3D model of the heart and torso. In the electrophysiology laboratory, body-surface electrodes were connected to the NEEES followed by unipolar EKG recordings during episodes of PVC/VT. The body-surface EKG data were processed by the NEEES using its inverse-problem solution software in combination with anatomical data from the heart and torso. The earliest site of activation as denoted on the NEEES 3D heart model was compared with the PVC/VT origin using a 3D electroanatomical mapping system. The site of successful catheter ablation served as final confirmation. A total of 21 PVC/VT morphologies were analysed and ablated. The chamber of interest was correctly diagnosed non-invasively in 20 of 21 (95%) PVC/VT cases. In 18 of the 21 (86%) cases, the correct ventricular segment was diagnosed. Catheter ablation resulted in acute success in 19 of the 20 (95%) patients, whereas 1 patient underwent successful surgical ablation. During 6 months of follow-up, 19 of the 20 (95%) patients were free from recurrence off antiarrhythmic drugs. Conclusion The NEEES accurately identified the site of PVC/VT origin. Knowledge of the potential site of the PVC/VT origin may aid the physician in planning a successful ablation strategy. PMID:27207812

  13. Regulatory Activities Related to Circumferential Cracking of Reactor Pressure Vessel Head Penetration Nozzles

    SciTech Connect

    Hiser, Allen L. Jr.

    2002-07-01

    The recent discoveries of cracked and leaking Alloy 600 vessel head penetration (VHP) nozzles, including control rod drive mechanism (CRDM) and thermocouple nozzles, at four pressurized water reactors (PWRs) have raised concerns about the structural integrity of VHP nozzles throughout the PWR industry. Nozzle cracking at Oconee Nuclear Station Unit 1 in November 2000 and Arkansas Nuclear One Unit 1 in February 2001 was limited to axial cracking, an occurrence deemed to be of limited safety concern in the NRC staff's generic safety evaluation on the cracking of VHP nozzles dated November 19, 1993. However, the discovery of circumferential cracking at Oconee Nuclear Station Unit 3 in February 2001 and Oconee Nuclear Station Unit 2 in April 2001 particularly the large circumferential cracking identified in two CRDM nozzles at ONS3 has raised concerns about the potential safety implications and prevalence of cracking in VHP nozzles in PWRs. In response to the circumferential cracking identified at the Oconee units, the NRC issued Bulletin 2001-01, 'Circumferential Cracking of Reactor Pressure Vessel Head Penetration Nozzles', on August 3, 2001. This bulletin requests information from licensees related to the structural integrity of the reactor pressure VHP nozzles for their facilities, including the extent of VHP nozzle leakage and cracking that has been found to date, the inspections and repairs that have been undertaken to satisfy applicable regulatory requirements, future plans to inspect VHP nozzles, and a description of how future inspection plans will ensure compliance with applicable regulatory requirements. This paper summarizes the staff's review and assessment of licensee responses to NRC Bulletin 2001-01. (author)

  14. Acquired tricuspid valve stenosis associated with two ventricular endocardial pacing leads in a dog.

    PubMed

    Tompkins, Emily; Dulake, Michelle I; Ghaffari, Shadie; Nakamura, Reid K

    2015-01-01

    Acquired tricuspid valve stenosis (TVS) is a rare complication of endocardial pacing lead implantation in humans that has only been described once previously in the veterinary literature in a dog with excessive lead redundancy. A 12 yr old terrier presented with right-sided congestive heart failure 6 mo after implantation of a second ventricular endocardial pacing lead. The second lead was placed due to malfunction of the first lead, which demonstrated abnormally low impedance. Transthoracic echocardiography identified hyperechoic tissue associated with the pacing leads as they crossed the tricuspid valve annulus as well as a stenotic tricuspid inflow pattern via spectral Doppler interrogation. Medical management was ultimately unsuccessful and the dog was euthanized 6 wk after TVS was diagnosed. The authors report the first canine case of acquired TVS associated with two ventricular endocardial pacing leads.

  15. Cell Autonomous Requirement of Endocardial Smad4 During Atrioventricular Cushion Development in Mouse Embryos

    PubMed Central

    Song, Langying; Zhao, Mei; Wu, Bingruo; Zhou, Bin; Wang, Qin; Jiao, Kai

    2011-01-01

    Atrioventricular (AV) cushions are the precursors of AV septum and valves. In this study, we examined roles of Smad4 during AV cushion development using a conditional gene inactivation approach. We found that endothelial/endocardial inactivation of Smad4 led to the hypocellular AV cushion defect and that both reduced cell proliferation and increased apoptosis contributed to the defect. Expression of multiple genes critical for cushion development was down-regulated in mutant embryos. In collagen gel assays, the number of mesenchymal cells formed is significantly reduced in mutant AV explants compared to that in control explants, suggesting that the reduction of cushion mesenchyme formation in mutants is unlikely secondary to their gross vasculature abnormalities. Using a previously developed immortal endocardial cell line, we showed that Smad4 is required for BMP signaling- stimulated upregulation of Tbx20 and Gata4. Therefore, our data collectively support the cell-autonomous requirement of endocardial Smad4 in regulating AV cushion development. PMID:21089072

  16. Tbx20 acts upstream of Wnt signaling to regulate endocardial cushion formation and valve remodeling during mouse cardiogenesis

    PubMed Central

    Cai, Xiaoqiang; Zhang, Weijia; Hu, Jun; Zhang, Lu; Sultana, Nishat; Wu, Bingruo; Cai, Weibin; Zhou, Bin; Cai, Chen-Leng

    2013-01-01

    Cardiac valves are essential to direct forward blood flow through the cardiac chambers efficiently. Congenital valvular defects are prevalent among newborns and can cause an immediate threat to survival as well as long-term morbidity. Valve leaflet formation is a rigorously programmed process consisting of endocardial epithelial-mesenchymal transformation (EMT), mesenchymal cell proliferation, valve elongation and remodeling. Currently, little is known about the coordination of the diverse signals that regulate endocardial cushion development and valve elongation. Here, we report that the T-box transcription factor Tbx20 is expressed in the developing endocardial cushions and valves throughout heart development. Ablation of Tbx20 in endocardial cells causes severe valve elongation defects and impaired cardiac function in mice. Our study reveals that endocardial Tbx20 is crucial for valve endocardial cell proliferation and extracellular matrix development, but is not required for initiation of EMT. Elimination of Tbx20 also causes aberrant Wnt/β-catenin signaling in the endocardial cushions. In addition, Tbx20 regulates Lef1, a key transcriptional mediator for Wnt/β-catenin signaling, in this developmental process. Our study suggests a model in which Tbx20 regulates the Wnt pathway to direct endocardial cushion maturation and valve elongation, and provides new insights into the etiology of valve defects in humans. PMID:23824573

  17. Long-term performance of epimyocardial pacing leads in adults: comparison with endocardial leads.

    PubMed

    Helguera, M E; Maloney, J D; Woscoboinik, J R; Trohman, R G; McCarthy, P M; Morant, V A; Wilkoff, B L; Castle, L W; Pinski, S L

    1993-03-01

    The long-term performance of epimyocardial pacing leads in children is well established, but few studies have analyzed the performance in adults. This issue has clinical relevance in view of the increased use of epimyocardial leads with implantable cardioverter defibrillator and antitachycardia pacing systems. We analyzed 93 epimyocardial pacing "systems" (121 leads: 65 unipolar, 28 bipolar) in adult patients (age 57 +/- 16 years), implanted since January 1980. Two different models were studied: Medtronic 4951 "Stab-on" (n = 35) and Medtronic 6917/6917A "Screw-in" (n = 58). A control group was created by randomly matching each epimyocardial system with two endocardial leads, according to age and year of implant. Epimyocardial and endocardial leads were followed-up for 44 +/- 35 and 43 +/- 35 months, respectively (P = NS). Freedom from failure for epimyocardial leads was 0.91 (95% Confidence Interval [95% CI] = 0.82 to 0.96) at 5 years, and 0.91 (95% CI = 0.69 to 0.98) at 10 years. No difference was found between the two analyzed models. Freedom from failure for endocardial leads was 0.97 (95% CI = 0.93 to 0.99) and 0.90 (95% CI = 0.61 to 0.97) at 5 and 10 years, respectively. Epimyocardial leads had a significantly poorer short-term survival than endocardial leads, secondarily to earlier "technique related" failures (P = 0.03; relative risk 3.0; Wilcoxon test). However, overall long-term performance was similar to endocardial leads. Epimyocardial pacing leads, meticulously implanted and tested, have a long-term performance similar to endocardial pacing leads.

  18. S1pr2/Gα13 signaling regulates the migration of endocardial precursors by controlling endoderm convergence.

    PubMed

    Xie, Huaping; Ye, Ding; Sepich, Diane; Lin, Fang

    2016-06-15

    Formation of the heart tube requires synchronized migration of endocardial and myocardial precursors. Our previous studies indicated that in S1pr2/Gα13-deficient embryos, impaired endoderm convergence disrupted the medial migration of myocardial precursors, resulting in the formation of two myocardial populations. Here we show that endoderm convergence also regulates endocardial migration. In embryos defective for S1pr2/Gα13 signaling, endocardial precursors failed to migrate towards the midline, and the presumptive endocardium surrounded the bilaterally-located myocardial cells rather than being encompassed by them. In vivo imaging of control embryos revealed that, like their myocardial counterparts, endocardial precursors migrated with the converging endoderm, though from a more anterior point, then moved from the dorsal to the ventral side of the endoderm (subduction), and finally migrated posteriorly towards myocardial precursors, ultimately forming the inner layer of the heart tube. In embryos defective for endoderm convergence due to an S1pr2/Gα13 deficiency, both the medial migration and the subduction of endocardial precursors were impaired, and their posterior migration towards the myocardial precursors was premature. This placed them medial to the myocardial populations, physically blocking the medial migration of the myocardial precursors. Furthermore, contact between the endocardial and myocardial precursor populations disrupted the epithelial architecture of the myocardial precursors, and thus their medial migration; in embryos depleted of endocardial cells, the myocardial migration defect was partially rescued. Our data indicate that endoderm convergence regulates the medial migration of endocardial precursors, and that premature association of the endocardial and myocardial populations contributes to myocardial migration defects observed in S1pr2/Gα13-deficient embryos. The demonstration that endoderm convergence regulates the synchronized

  19. Modified circumferential torsoplasty for the massive-weight-loss patient.

    PubMed

    Davison, Steven P; Clemens, Mark W; Chang, Suzie

    2007-10-01

    Obesity is an increasing national public health issue that has reached epidemic proportions over the past several decades. With new surgical advances in bariatric surgery, the massive-weight-loss patient population is on the rise. The generalized redundancy of skin following massive weight-loss, including lateral flank rolls, abdominal excesses, and buttock ptosis, is a problem amenable only by surgical excision. The circumferential torsoplasty has enabled the plastic surgeon to dramatically help this patient population. However, a problem exists in a size mismatch of the abdomen between the upper and lower circumferential flaps, leading to contour deformities. This study reports on 3 cases of circumferential torsoplasty, with modified lateral skin wedge resection treated by a single surgeon. The preoperative markings, technical aspects of the surgery, postoperative care, and outcomes are reviewed. Patients in all 3 cases achieved improved body contour. To date, there have been no postoperative complications of the study participants. We propose a new modification to the circumferential torsoplasty that simultaneously eliminates the lateral dog-ears and prevents recurrence of saddlebag deformities commonly encountered in the traditional circumferential torsoplasty. A wedge excision of lateral thigh skin to deep investing fascia is primarily closed and simultaneously equalizes flap length and tightens the thigh area. The scars are well accepted by patients.

  20. Increased number of cerebral emboli during percutaneous endocardial pulmonary vein isolation versus a thoracoscopic epicardial approach.

    PubMed

    Sauren, Loes D; la Meir, Mark; de Roy, Luc; Pison, Laurent; van der Veen, Frederik H; Mess, Werner H; Crijns, Harry J; Maessen, Jos G

    2009-11-01

    Pulmonary vein isolation (PVI) using ablation energy appears an effective treatment for atrial fibrillation (AF) with a success rate of approximately 80%. However, post-procedural neurological complications still occur in 0.5-10% of all patients undergoing PVI, presumably due to embolism. Therefore, we investigated the occurrence of cerebral micro-embolic signals (MES) as a surrogate marker for the risk of neurological impairment of two different PVI methods: (1) percutaneous endocardial radio-frequency (RF) ablation and (2) thoracoscopic epicardial ablation using RF energy. Ten patients (eight persistent AF and two paroxysmal AF) underwent a minimally invasive thoracoscopic epicardial (EPI) RF ablation and 10 patients (one persistent AF and nine paroxysmal AF) underwent a percutaneous endocardial (ENDO) isolation. Transcranial Doppler (TCD) was used to detect an MES in the middle cerebral arteries. An average of 5 (+/-6) MES were detected during epicardial PVI procedure versus 3908 (+/-2816) MES during percutaneous endocardial PVI procedure. During the ablation application period, respectively, 1 (+/-1) and 2566 (+/-2296) cerebral MES were detected. Cerebral micro-emboli during epicardial ablation are almost absent when compared to the thousands of emboli measured during percutaneous endocardial ablation.

  1. Endocardial and epicardial epithelial to mesenchymal transitions in heart development and disease

    PubMed Central

    von Gise, Alexander; Pu, William T.

    2012-01-01

    Epithelial to mesenchymal transition (EMT) converts epithelial cells to mobile and developmentally plastic mesenchymal cells. All cells in the heart arise from one or more EMTs. Within the developing heart, endocardial and epicardial EMTs produce most of the non-cardiomyocyte lineages of the mature heart. Endocardial EMT generates valve progenitor cells and is necessary for formation of the cardiac valves and for complete cardiac septation. Epicardial EMT is required for myocardial growth and coronary vessel formation, and generates cardiac fibroblasts, vascular smooth muscle cells, a subset of coronary endothelial cells, and possibly a subset of cardiomyocytes. Emerging studies suggest that these developmental mechanisms are redeployed in adult heart valve disease, in cardiac fibrosis, and in myocardial responses to ischemic injury. Redirection and amplification of disease-related EMTs offer potential new therapeutic strategies and approaches for treatment of heart disease. Here we review the role and molecular regulation of endocardial and epicardial EMT in fetal heart development, and we summarize key literature implicating reactivation of endocardial and epicardial EMT in adult heart disease. PMID:22679138

  2. Endocardial to Myocardial Notch-Wnt-Bmp Axis Regulates Early Heart Valve Development

    PubMed Central

    Wang, Yidong; Wu, Bingruo; Chamberlain, Alyssa A.; Lui, Wendy; Koirala, Pratistha; Susztak, Katalin; Klein, Diana; Taylor, Verdon; Zhou, Bin

    2013-01-01

    Endocardial to mesenchymal transformation (EMT) is a fundamental cellular process required for heart valve formation. Notch, Wnt and Bmp pathways are known to regulate this process. To further address how these pathways coordinate in the process, we specifically disrupted Notch1 or Jagged1 in the endocardium of mouse embryonic hearts and showed that Jagged1-Notch1 signaling in the endocardium is essential for EMT and early valvular cushion formation. qPCR and RNA in situ hybridization assays reveal that endocardial Jagged1-Notch1 signaling regulates Wnt4 expression in the atrioventricular canal (AVC) endocardium and Bmp2 in the AVC myocardium. Whole embryo cultures treated with Wnt4 or Wnt inhibitory factor 1 (Wif1) show that Bmp2 expression in the AVC myocardium is dependent on Wnt activity; Wnt4 also reinstates Bmp2 expression in the AVC myocardium of endocardial Notch1 null embryos. Furthermore, while both Wnt4 and Bmp2 rescue the defective EMT resulting from Notch inhibition, Wnt4 requires Bmp for its action. These results demonstrate that Jagged1-Notch1 signaling in endocardial cells induces the expression of Wnt4, which subsequently acts as a paracrine factor to upregulate Bmp2 expression in the adjacent AVC myocardium to signal EMT. PMID:23560082

  3. Structural and leakage integrity of tubes affected by circumferential cracking

    SciTech Connect

    Hernalsteen, P.

    1997-02-01

    In this paper the author deals with the notion that circumferential cracks are generally considered unacceptable. He argues for the need to differentiate two facets of such cracks: the issue of the size and growth rate of a crack; and the issue of the structural strength and leakage potential of the tube in the presence of the crack. In this paper the author tries to show that the second point is not a major concern for such cracks. The paper presents data on the structural strength or burst pressure characteristics of steam generator tubes derived from models and data bases of experimental work. He also presents a leak rate model, and compares the performance of circumferential and axial cracks as far as burst strength and leak rate. The final conclusion is that subject to improvement in NDE capabilities (sizing, detection, growth), that Steam Generator Defect Specific Management can be used to allow circumferentially degraded tubes to remain in service.

  4. Increased regurgitant flow causes endocardial cushion defects in an avian embryonic model of congenital heart disease.

    PubMed

    Ford, Stephanie M; McPheeters, Matthew T; Wang, Yves T; Ma, Pei; Gu, Shi; Strainic, James; Snyder, Christopher; Rollins, Andrew M; Watanabe, Michiko; Jenkins, Michael W

    2017-05-01

    The relationship between changes in endocardial cushion and resultant congenital heart diseases (CHD) has yet to be established. It has been shown that increased regurgitant flow early in embryonic heart development leads to endocardial cushion defects, but it remains unclear how abnormal endocardial cushions during the looping stages might affect the fully septated heart. The goal of this study was to reproducibly alter blood flow in vivo and then quantify the resultant effects on morphology of endocardial cushions in the looping heart and on CHDs in the septated heart. Optical pacing was applied to create regurgitant flow in embryonic hearts, and optical coherence tomography (OCT) was utilized to quantify regurgitation and morphology. Embryonic quail hearts were optically paced at 3 Hz (180 bpm, well above intrinsic rate 60-110 bpm) at stage 13 of development (3-4 weeks human) for 5 min. Pacing fatigued the heart and led to at least 1 h of increased regurgitant flow. Resultant morphological changes were quantified with OCT imaging at stage 19 (cardiac looping-4-5 weeks human) or stage 35 (4 chambered heart-8 weeks human). All paced embryos imaged at stage 19 displayed structural changes in cardiac cushions. The amount of regurgitant flow immediately after pacing was inversely correlated with cardiac cushion size 24-h post pacing (P value < .01). The embryos with the most regurgitant flow and smallest cushions after pacing had a decreased survival rate at 8 days (P < .05), indicating that those most severe endocardial cushion defects were lethal. Of the embryos that survived to stage 35, 17/18 exhibited CHDs including valve defects, ventricular septal defects, hypoplastic ventricles, and common AV canal. The data illustrate a strong inverse relationship in which regurgitant flow precedes abnormal and smaller cardiac cushions, resulting in the development of CHDs. © 2016 Wiley Periodicals, Inc.

  5. Soft Tissue Reconstruction of Complete Circumferential Defects of the Upper Extremity

    PubMed Central

    Ng, Zhi Yang; Tan, Shaun Shi Yan; Lellouch, Alexandre Gaston; Chim, Harvey Wei Ming

    2017-01-01

    Background Upper extremity soft tissue defects with complete circumferential involvement are not common. Coupled with the unique anatomy of the upper extremity, the underlying etiology of such circumferential soft tissue defects represent additional reconstructive challenges that require treatment to be tailored to both the patient and the wound. The aim of this study is to review the various options for soft tissue reconstruction of complete circumferential defects in the upper extremity. Methods A literature review of PubMed and MEDLINE up to December 2016 was performed. The current study focuses on forearm and arm defects from the level at or proximal to the wrist and were assessed based on Tajima's classification (J Trauma 1974). Data reviewed for analysis included patient demographics, causality, defect size, reconstructive technique(s) employed, and postoperative follow-up and functional outcomes (when available). Results In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, 14 unique articles were identified for a total of 50 patients (mean=28.1 years). Underlying etiologies varied from extensive thermal or electrical burns to high impact trauma leading to degloving or avulsion, crush injuries, or even occur iatrogenically after tumor extirpation or extensive debridement. Treatment options ranged from the application of negative pressure wound dressings to the opposite end of the spectrum in hand transplantation. Conclusions With the evolution of reconstructive techniques over time, the extent of functional and aesthetic rehabilitation of these complex upper extremity injuries has also improved. The proposed management algorithm comprehensively addresses the inherent challenges associated with these complex cases. PMID:28352600

  6. Magnetic resonance imaging characterization of circumferential and longitudinal strain under various coronary interventions in swine

    PubMed Central

    Suhail, Mohammed SA; Wilson, Mark W; Hetts, Steven W; Saeed, Maythem

    2013-01-01

    AIM: To compare the acute changes in circumferential and longitudinal strain after exposing a coronary artery to various interventions in swine. METHODS: Percutaneous balloon angioplasty catheter was guided to location aid device (LAD) under X-ray fluoroscopy to create different patterns of ischemic insults. Pigs (n = 32) were equally divided into 4 groups: controls, 90 min LAD occlusion/reperfusion, LAD microembolization, and combined LAD occlusion/microembolization/reperfusion. Three days after interventions, cine, tagged and viability magnetic resonance imaging (MRI) were acquired to measure and compare left and right circumferential strain, longitudinal strain and myocardial viability, respectively. Measurements were obtained using HARP and semi-automated threshold method and statistically analyzed using unpaired t-test. Myocardial and vascular damage was characterized microscopically. RESULTS: Coronary microemboli caused greater impairment in l left ventricular (LV) circumferential strain and dyssynchrony than LAD occlusion/reperfusion despite the significant difference in the extent of myocardial damage. Microemboli also caused significant decrease in peak systolic strain rate of remote myocardium and LV dyssynchrony. Cine MRI demonstrated the interaction between LV and right ventricular (RV) at 3 d after interventions. Compensatory increase in RV free wall longitudinal strain was seen in response to all interventions. Viability MRI, histochemical staining and microscopy revealed different patterns of myocardial damage and microvascular obstruction. CONCLUSION: Cine MRI revealed subtle changes in LV strain caused by various ischemic insults. It also demonstrated the interaction between the right and left ventricles after coronary interventions. Coronary microemboli with and without acute myocardial infarction (AMI) cause complex myocardial injury and ventricular dysfunction that is not replicated in solely AMI. PMID:24379934

  7. Quantification of biventricular myocardial function using cardiac magnetic resonance feature tracking, endocardial border delineation and echocardiographic speckle tracking in patients with repaired tetralogy of Fallot and healthy controls.

    PubMed

    Kempny, Aleksander; Fernández-Jiménez, Rodrigo; Orwat, Stefan; Schuler, Pia; Bunck, Alexander C; Maintz, David; Baumgartner, Helmut; Diller, Gerhard-Paul

    2012-05-31

    Parameters of myocardial deformation have been suggested to be superior to conventional measures of ventricular function in patients with tetralogy of Fallot (ToF), but have required non-routine, tagged cardiovascular magnetic resonance (CMR) techniques. We assessed biventricular myocardial function using CMR cine-based feature tracking (FT) and compared it to speckle tracking echocardiography (STE) and to simple endocardial border delineation (EBD). In addition, the relation between parameters of myocardial deformation and clinical parameters was assessed. Overall, 28 consecutive adult patients with repaired ToF (age 40.4 ± 13.3 years) underwent standard steady-state-free precession sequence CMR, echocardiography, and cardiopulmonary exercise testing. In addition, 25 healthy subjects served as controls. Myocardial deformation was assessed by CMR based FT (TomTec Diogenes software), CMR based EBD (using custom written software) and STE (TomTec Cardiac Performance Analysis software). Feature tracking was feasible in all subjects. A close agreement was found between measures of global left (LV) and right ventricular (RV) global strain. Interobserver agreement for FT and STE was similar for longitudinal LV global strain, but FT showed better inter-observer reproducibility than STE for circumferential or radial LV and longitudinal RV global strain. Reproducibility of regional strain on FT was, however, poor. The relative systolic length change of the endocardial border measured by EBD yielded similar results to FT global strain. Clinically, biventricular longitudinal strain on FT was reduced compared to controls (P < 0.0001) and was related to the number of previous cardiac operations. In addition, FT derived RV strain was related to exercise capacity and VE/VCO2-slope. Although neither the inter-study reproducibility nor accuracy of FT software were investigated, and its inter-observer reproducibility for regional strain calculation was poor, its

  8. Quantification of biventricular myocardial function using cardiac magnetic resonance feature tracking, endocardial border delineation and echocardiographic speckle tracking in patients with repaired tetralogy of fallot and healthy controls

    PubMed Central

    2012-01-01

    Background Parameters of myocardial deformation have been suggested to be superior to conventional measures of ventricular function in patients with tetralogy of Fallot (ToF), but have required non-routine, tagged cardiovascular magnetic resonance (CMR) techniques. We assessed biventricular myocardial function using CMR cine-based feature tracking (FT) and compared it to speckle tracking echocardiography (STE) and to simple endocardial border delineation (EBD). In addition, the relation between parameters of myocardial deformation and clinical parameters was assessed. Methods Overall, 28 consecutive adult patients with repaired ToF (age 40.4 ± 13.3 years) underwent standard steady-state-free precession sequence CMR, echocardiography, and cardiopulmonary exercise testing. In addition, 25 healthy subjects served as controls. Myocardial deformation was assessed by CMR based FT (TomTec Diogenes software), CMR based EBD (using custom written software) and STE (TomTec Cardiac Performance Analysis software). Results Feature tracking was feasible in all subjects. A close agreement was found between measures of global left (LV) and right ventricular (RV) global strain. Interobserver agreement for FT and STE was similar for longitudinal LV global strain, but FT showed better inter-observer reproducibility than STE for circumferential or radial LV and longitudinal RV global strain. Reproducibility of regional strain on FT was, however, poor. The relative systolic length change of the endocardial border measured by EBD yielded similar results to FT global strain. Clinically, biventricular longitudinal strain on FT was reduced compared to controls (P < 0.0001) and was related to the number of previous cardiac operations. In addition, FT derived RV strain was related to exercise capacity and VE/VCO2-slope. Conclusions Although neither the inter-study reproducibility nor accuracy of FT software were investigated, and its inter-observer reproducibility for regional

  9. Rotating stall control in a high-speed stage with inlet distortion. Part 2: Circumferential distortion

    SciTech Connect

    Spakovszky, Z.S.; Weigl, H.J.; Paduano, J.D.; Schalkwyk, C.M. van; Suder, K.L.; Bright, M.M.

    1999-07-01

    This paper presents the first attempt to stabilize rotating stall in a single-stage transonic axial flow compressor with inlet distortion using active feedback control. The experiments were conducted at the NASA Lewis Research Center on a single-stage transonic core compressor inlet stage. An array of 12 jet injectors located upstream of the compressor was used for forced response testing and feedback stabilization. Results for a circumferential total pressure distortion of about one dynamic head and a 120 deg extent (DC(60){equals}0.61) are reported in this paper. Part 1 (Spaskovszky et al., 1999) reports results for radial distortion. Control laws were designed using empirical transfer function estimates determined from forced response results. Distortion introduces coupling between the harmonics of circumferential pressure perturbations, requiring multivariable identification and control design techniques. The compressor response displayed a strong first spatial harmonic, dominated by the well-known incompressible Moore-Greitzer mode. Steady axisymmetric injection of 4 percent of the compressor mass flow resulted in a 6.2 percent reduction of stalling mass flow. Constant gain feedback, using unsteady asymmetric injection, yielded a further range extension of 9 percent. A more sophisticated robust H{sub {infinity}} controller allowed a reduction in stalling mass flow of 10.2 percent relative to steady injection, yielding a total reduction in stalling mass flow of 16.4 percent.

  10. Status of the steam generator tube circumferential ODSCC degradation experienced at the Doel 4 plant

    SciTech Connect

    Roussel, G.

    1997-02-01

    Since the 1991 outage, the Doel Unit 4 nuclear power plant is known to be affected by circumferential outside diameter intergranular stress corrosion cracking at the hot leg tube expansion transition. Extensive non destructive examination inspections have shown the number of tubes affected by this problem as well as the size of the cracks to have been increasing for the three cycles up to 1993. As a result of the high percentage of tubes found non acceptable for continued service after the 1993 in-service inspection, about 1,700 mechanical sleeves were installed in the steam generators. During the 1994 outage, all the tubes sleeved during the 1993 outage were considered as potentially cracked to some extent at the upper hydraulic transition and were therefore not acceptable for continued service. They were subsequently repaired by laser welding. Furthermore all the tubes not sleeved during the 1993 outage were considered as not acceptable for continued service and were repaired by installing laser welded sleeves. During the 1995 outage, some unexpected degradation phenomena were evidenced in the sleeved tubes. This paper summarizes the status of the circumferential ODSCC experienced in the SG tubes of the Doel 4 plant as well as the other connected degradation phenomena.

  11. Reciprocal myocardial-endocardial interactions pattern the delay in atrioventricular junction conduction

    PubMed Central

    Bressan, Michael; Yang, PoAn Brian; Louie, Jonathan D.; Navetta, Alicia M.; Garriock, Robert J.; Mikawa, Takashi

    2014-01-01

    Efficient blood flow depends on two developmental processes that occur within the atrioventricular junction (AVJ) of the heart: conduction delay, which entrains sequential chamber contraction; and valve formation, which prevents retrograde fluid movement. Defects in either result in severe congenital heart disease; however, little is known about the interplay between these two crucial developmental processes. Here, we show that AVJ conduction delay is locally assigned by the morphogenetic events that initiate valve formation. Our data demonstrate that physical separation from endocardial-derived factors prevents AVJ myocardium from becoming fast conducting. Mechanistically, this physical separation is induced by myocardial-derived factors that support cardiac jelly deposition at the onset of valve formation. These data offer a novel paradigm for conduction patterning, whereby reciprocal myocardial-endocardial interactions coordinate the processes of valve formation with establishment of conduction delay. This, in turn, synchronizes the electrophysiological and structural events necessary for the optimization of blood flow through the developing heart. PMID:25273084

  12. Circumferential body contouring in bariatric and non-bariatric patient.

    PubMed

    Vico, Pierre G; De Vooght, Axel; Nokerman, Béatrice

    2010-05-01

    Obesity is a serious global health-care concern, with rates in Europe and North America estimated at about 20-30% of the adult population. Bariatric surgery forms the basis of modified surgical approaches to body-contouring procedures, especially those involving circumferential abdominoplasty. This procedure produces tremendous aesthetic results with very high patient satisfaction. We applied this technique, as an alternative to classic abdominoplasty, on moderately to severely obese patients and on patients with no excess-weight problem but some degree of skin laxity and with no history of bariatric surgery. The first author performed 80 consecutive circumferential abdominoplasties during a 4-year period. The patients consisted of two groups: post-bariatric patients (n=23) and those with no history of bariatric surgery (n=57). Factors such as age, gender, duration of the procedure and hospitalisation, among other relevant ones, are studied and the data are compared between the two groups, with a third group of patients who underwent, during the same period, a classical abdominoplasty (n=38), and with data from the literature. Circumferential abdominoplasty produces excellent aesthetical results with a high degree of satisfaction for patients with no bariatric history. The patients in this group are younger, their preoperative weight loss is lower, operative time shorter and per-operative blood loss lower. There is no statistical difference between the groups in terms either of the body mass index (BMI) at the time of circumferential abdominoplasty or of the resected tissue weight. Morbidity and rate of complications between these groups are not significant statistically, as with the case of data available in the literature. Compared with patients undergoing a classical abdominoplasty, we observe more complications related to delay in wound healing, less haematoma and less combined procedures in cases of circumferential abdominoplasty. Circumferential

  13. Endocardial cell epithelial-mesenchymal transformation requires Type III TGFβ receptor interaction with GIPC.

    PubMed

    Townsend, Todd A; Robinson, Jamille Y; How, Tam; DeLaughter, Daniel M; Blobe, Gerard C; Barnett, Joey V

    2012-01-01

    An early event in heart valve formation is the epithelial-mesenchymal transformation (EMT) of a subpopulation of endothelial cells in specific regions of the heart tube, the endocardial cushions. The Type III TGFβ receptor (TGFβR3) is required for TGFβ2- or BMP-2-stimulated EMT in atrioventricular endocardial cushion (AVC) explants in vitro but the mediators downstream of TGFβR3 are not well described. Using AVC and ventricular explants as an in vitro assay, we found an absolute requirement for specific TGFβR3 cytoplasmic residues, GAIP-interacting protein, C terminus (GIPC), and specific Activin Receptor-Like Kinases (ALK)s for TGFβR3-mediated EMT when stimulated by TGFβ2 or BMP-2. The introduction of TGFβR3 into nontransforming ventricular endocardial cells, followed by the addition of either TGFβ2 or BMP-2, results in EMT. TGFβR3 lacking the entire cytoplasmic domain, or only the 3C-terminal amino acids that are required to bind GIPC, fails to support EMT in response to TGFβ2 or BMP-2. Overexpression of GIPC in AVC endocardial cells enhanced EMT while siRNA-mediated silencing of GIPC in ventricular cells overexpressing TGFβR3 significantly inhibited EMT. Targeting of specific ALKs by siRNA revealed that TGFβR3-mediated EMT requires ALK2 and ALK3, in addition to ALK5, but not ALK4 or ALK6. Taken together, these data identify GIPC, ALK2, ALK3, and ALK5 as signaling components required for TGFβR3-mediated endothelial cell EMT. Copyright © 2011. Published by Elsevier Inc.

  14. ENDOCARDIAL CELL EPITHELIAL-MESENCHYMAL TRANSFORMATION REQUIRES TYPE III TGFβ RECEPTOR INTERACTION WITH GIPC

    PubMed Central

    Townsend, Todd A.; Robinson, Jamille Y.; How, Tam; DeLaughter, Daniel M.; Blobe, Gerard C.; Barnett, Joey V.

    2011-01-01

    An early event in heart valve formation is the epithelial-mesenchymal transformation (EMT) of a subpopulation of endothelial cells in specific regions of the heart tube, the endocardial cushions. The Type III TGFβ receptor (TGFβR3) is required for TGFβ2- or BMP-2-stimulated EMT in atrioventricular endocardial cushion (AVC) explants in vitro but the mediators downstream of TGFβR3 are not well described. Using AVC and ventricular explants as an in vitro assay, we found an absolute requirement for specific TGFβR3 cytoplasmic residues, GAIP-interacting protein, C terminus (GIPC), and specific Activin Receptor-Like Kinases (ALK)s for TGFβR3-mediated EMT when stimulated by TGFβ2 or BMP-2. The introduction of TGFβR3 into nontransforming ventricular endocardial cells, followed by the addition of either TGFβ2 or BMP-2, results in EMT. TGFβR3 lacking the entire cytoplasmic domain, or only the 3 C-terminal amino acids that are required to bind GIPC, fails to support EMT in response to TGFβ2 or BMP-2. Overexpression of GIPC in AVC endocardial cells enhanced EMT while siRNA-mediated silencing of GIPC in ventricular cells overexpressing TGFβR3 significantly inhibited EMT. Targeting of specific ALK’s by siRNA revealed that TGFβR3-mediated EMT requires ALK2 and ALK3, in addition to ALK5, but not ALK4 or ALK6. Taken together, these data identify GIPC, ALK2, ALK3, and ALK5 as signaling components required for TGFβR3-mediated endothelial cell EMT. PMID:21945156

  15. Tip surface changes in endocardial stimulation electrode, visualised by scanning electron microscopy.

    PubMed

    Hladky, M; Horn, V; Kamaryt, P; Cabanova, J; Zeman, K

    1975-01-01

    The authors have been probably the first investigators who applied scanning electron microscopy to studies of the changes occurring in the surface of the metalic tip of an endocardial stimulating electrode. They found a lowered conductivity for secondary electron emission, and describe the surface changes in a platiniridium-tipped electrode which had been used for almost four years, in comparison with an unused electrode.

  16. 46 CFR 52.05-45 - Circumferential joints in pipes, tubes and headers (modifies PW-41).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Circumferential joints in pipes, tubes and headers... Circumferential joints in pipes, tubes and headers (modifies PW-41). (a) Circumferential welded joints of pipes, tubes and headers shall be as required by PW-41 of section I of the ASME Boiler and Pressure Vessel...

  17. 46 CFR 52.05-45 - Circumferential joints in pipes, tubes and headers (modifies PW-41).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Circumferential joints in pipes, tubes and headers... Circumferential joints in pipes, tubes and headers (modifies PW-41). (a) Circumferential welded joints of pipes, tubes and headers shall be as required by PW-41 of section I of the ASME Boiler and Pressure Vessel...

  18. 46 CFR 52.05-45 - Circumferential joints in pipes, tubes and headers (modifies PW-41).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Circumferential joints in pipes, tubes and headers... Circumferential joints in pipes, tubes and headers (modifies PW-41). (a) Circumferential welded joints of pipes, tubes and headers shall be as required by PW-41 of section I of the ASME Boiler and Pressure Vessel...

  19. 46 CFR 52.05-45 - Circumferential joints in pipes, tubes and headers (modifies PW-41).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Circumferential joints in pipes, tubes and headers... Circumferential joints in pipes, tubes and headers (modifies PW-41). (a) Circumferential welded joints of pipes, tubes and headers shall be as required by PW-41 of section I of the ASME Boiler and Pressure Vessel...

  20. 46 CFR 52.05-45 - Circumferential joints in pipes, tubes and headers (modifies PW-41).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Circumferential joints in pipes, tubes and headers... Circumferential joints in pipes, tubes and headers (modifies PW-41). (a) Circumferential welded joints of pipes, tubes and headers shall be as required by PW-41 of section I of the ASME Boiler and Pressure Vessel...

  1. Cell autonomous requirement of endocardial Smad4 during atrioventricular cushion development in mouse embryos.

    PubMed

    Song, Langying; Zhao, Mei; Wu, Bingruo; Zhou, Bin; Wang, Qin; Jiao, Kai

    2011-01-01

    Atrioventricular (AV) cushions are the precursors of AV septum and valves. In this study, we examined roles of Smad4 during AV cushion development using a conditional gene inactivation approach. We found that endothelial/endocardial inactivation of Smad4 led to the hypocellular AV cushion defect and that both reduced cell proliferation and increased apoptosis contributed to the defect. Expression of multiple genes critical for cushion development was down-regulated in mutant embryos. In collagen gel assays, the number of mesenchymal cells formed is significantly reduced in mutant AV explants compared to that in control explants, suggesting that the reduction of cushion mesenchyme formation in mutants is unlikely secondary to their gross vasculature abnormalities. Using a previously developed immortal endocardial cell line, we showed that Smad4 is required for BMP signaling- stimulated upregulation of Tbx20 and Gata4. Therefore, our data collectively support the cell-autonomous requirement of endocardial Smad4 in regulating AV cushion development. © 2010 Wiley-Liss, Inc.

  2. Conjunction of Endocardial and Coronary Venous System Mapping to Ablate Ventricular Arrhythmias

    PubMed Central

    Wo, Hung-Ta; Yeh, Jih-Kai; Chang, Po-Cheng; Wen, Ming-Shien; Wang, Chun-Chieh; Chou, Chung-Chuan; Yeh, San-Jou

    2016-01-01

    Background Ablation of idiopathic ventricular arrhythmias (VAs) with epicardial or intramural origins is technically challenging. Herein, we have described the successful ablation of left VAs via the coronary venous system (CVS) in conjunction with endocardial map guided by three-dimensional electroanatomical map in six patients. Methods Out of a total consecutive 84 patients with symptomatic idiopathic VAs, radiofrequency ablation via the CVS was performed on six patients (7%). Furthermore, we reviewed patient records and electrophysiologic studies with respect to clinical characteristics. Results Activation map was conducted in 5 patients, and the earliest activation sites were identified within the CVS. The preceding times to the onset of QRS complex were longer than those at the earliest endocardial sites (36.2 ± 5.6 ms vs. 14.2 ± 6.4 ms, p = 0.02, n = 5). Spiky fractionated long-duration potentials were recorded at the successful ablation sites in all 5 patients. The other patient received pacemapping only because of few spontaneous VAs during the procedure, and the best pacemap spot was found within the CVS. Irrigated catheters were required in 4 out of 6 patients because VAs were temporarily suppressed with regular ones. Conclusions Idiopathic VAs can be ablated via the CVS in conjunction with endocardial mapping. Additionally, spiky fractionated long-duration potential can function as a clue to identify the good ablation site. PMID:27274177

  3. Combined use of non-thoracotomy cardioverter defibrillators and endocardial pacemakers.

    PubMed Central

    Noguera, H. H.; Peralta, A. O.; John, R. M.; Venditti, F. J.; Martin, D. T.

    1997-01-01

    OBJECTIVE: To study the potential interactions in patients with endocardial permanent pacemakers and non-thoracotomy implantable cardioverter defibrillator (ICD) systems. DESIGN: Case series and cohort study. SETTING: Tertiary referral centre. PATIENTS: Fifteen consecutive patients with both endocardial pacemakers (12 dual chamber and three single chamber) and non-thoracotomy ICD systems. MAIN OUTCOME MEASURES: Detection inhibition of induced ventricular fibrillation; double counting; and pacemaker function after shocks. In the evaluation of detection inhibition, 124 VF inductions were analysed for detection duration compared with induced VF episodes in controls with an ICD but without a pacemaker. RESULTS: Two patients (13%) showed detection inhibition of VF and required pacemaker system change at the time of the ICD implant. With the final lead position, despite frequent pacemaker undersensing of VF, ICD detection of VF was not inhibited during any induction, and neither initial detection nor redetection times for VF were different from controls. Double/triple counting of pacemaker artefact and evoked electrogram was noted in three patients (20%). In two, this was remedied during the implantation procedure, and in the other it was abolished when amiodarone treatment was discontinued. Pacemaker function was affected by ICD discharges in two patients, one who showed postshock atrial undersensing and loss of capture, and another whose pacemaker reverted to VVI mode. CONCLUSIONS: When careful testing is performed at implantation to detect and remedy device interactions, non-thoracotomy ICD treatment and endocardial pacemakers can be used safely in combination. Images PMID:9290402

  4. Magnetic resonance imaging receiver coil decoupling using circumferential shielding structures.

    PubMed

    Yeh, Jhy-Neng Tasso; Fa-Hsuan Lin

    2016-08-01

    We propose a flexible phased-array design using circular coils with circumferential shielding structure to achieve robust decoupling between coil elements when the array is either bended or on a flat plane. Two types of circumferential shielding were tested through numerical simulation and imaging experiment. The results demonstrated that our arrays have good decoupling between coils when they are on a curved surface with S21 <; -16.72 dB. Both types perform higher SNR images than a commercially available 32-channel adult head coil array. Future work will empirically construct a multi-channel array with the number of channel matched to commercial phased array in order to validate the performance in vivo.

  5. Circumferential pressure distributions in a model labyrinth seal

    NASA Technical Reports Server (NTRS)

    Leong, Y. M. M. S.; Brown, R. D.

    1982-01-01

    A research program to isolate and study leakage flow through labyrinth glands was initiated. Circumferential pressure distributions were measured in the labyrinth glands with geometry appropriate to the high pressure labyrinths in large steam turbines. Knowledge of this pressure distribution is essential as it is this unequal pressure field that results in the destabilizing force. Parameters that are likely to affect the pressure distributions are incorporated into the test rig. Some preliminary pressure profiles are presented.

  6. Circumferential gap propagation in an anisotropic elastic bacterial sacculus

    NASA Astrophysics Data System (ADS)

    Taneja, Swadhin; Levitan, Benjamin A.; Rutenberg, Andrew D.

    2014-01-01

    We have modeled stress concentration around small gaps in anisotropic elastic sheets, corresponding to the peptidoglycan sacculus of bacterial cells, under loading corresponding to the effects of turgor pressure in rod-shaped bacteria. We find that under normal conditions the stress concentration is insufficient to mechanically rupture bacteria, even for gaps up to a micron in length. We then explored the effects of stress-dependent smart autolysins, as hypothesized by A. L. Koch [Adv. Microb. Physiol. 24, 301 (1983), 10.1016/S0065-2911(08)60388-4; Res. Microbiol. 141, 529 (1990), 10.1016/0923-2508(90)90017-K]. We show that the measured anisotropic elasticity of the peptidoglycan (PG) sacculus can lead to stable circumferential propagation of small gaps in the sacculus. This is consistent with the recent observation of circumferential propagation of PG-associated MreB patches in rod-shaped bacteria. We also find a bistable regime of both circumferential and axial gap propagation, which agrees with behavior reported in cytoskeletal mutants of B. subtilis. We conclude that the elastic anisotropies of a bacterial sacculus, as characterized experimentally, may be relevant for maintaining rod-shaped bacterial growth.

  7. Circumferential nonlocal effect on the buckling and vibration of nanotubes

    NASA Astrophysics Data System (ADS)

    Wang, Cheng Yuan; Li, Xiao Hu; Luo, Ying

    2016-04-01

    The nonlocal beam theories are widely used to study the mechanics of cylindrical nanotubes (NTs). The one-dimensional models however are unable to account for the nonlocal effect in the circumferential direction, which may substantially affect the applicability of the nonlocal beam models. To address the issue this letter examines the circumferential nonlocal effect (CNE) on the buckling and vibration of the NTs. Here the CNE is characterized by the difference between the nonlocal beam model considering the axial nonlocal effect only and the nonlocal shell model with both axial and circumferential nonlocal effects. The aspect ratio and radius-dependence of the CNE are calculated for the singlewall carbon NTs selected as a typical example. The results show that the CNE is substantial for the buckling and vibration of the NTs with small radius (e.g., <1 nm) and aspect ratio (e.g., <15). It however decreases with the rising radius and the aspect ratio, and turns out to be small for relatively wide and long NTs. The nonlocal beam theories thus may overestimate the buckling load and vibration frequency for the thin and short NTs.

  8. Comparison of NOGA Endocardial Mapping and Cardiac Magnetic Resonance Imaging for Determining Infarct Size and Infarct Transmurality for Intramyocardial Injection Therapy Using Experimental Data

    PubMed Central

    Pavo, Noemi; Jakab, Andras; Emmert, Maximilian Y.; Strebinger, Georg; Wolint, Petra; Zimmermann, Matthias; Ankersmit, Hendrik Jan; Hoerstrup, Simon P.; Maurer, Gerald; Gyöngyösi, Mariann

    2014-01-01

    Objectives We compared the accuracy of NOGA endocardial mapping for delineating transmural and non-transmural infarction to the results of cardiac magnetic resonance imaging (cMRI) with late gadolinium enhancement (LE) for guiding intramyocardial reparative substance delivery using data from experimental myocardial infarction studies. Methods Sixty domestic pigs underwent diagnostic NOGA endocardial mapping and cMRI-LE 60 days after induction of closed-chest reperfused myocardial infarction. The infarct size was determined by LE of cMRI and by delineation of the infarct core on the unipolar voltage polar map. The sizes of the transmural and non-transmural infarctions were calculated from the cMRI transmurality map using signal intensity (SI) cut-offs of>75% and>25% and from NOGA bipolar maps using bipolar voltage cut-off values of <0.8 mV and <1.9 mV. Linear regression analysis and Bland-Altman plots were used to determine correlations and systematic differences between the two images. The overlapping ratios of the transmural and non-transmural infarcted areas were calculated. Results Infarct size as determined by 2D NOGA unipolar voltage polar mapping correlated with the 3D cMRI-LE findings (r = 0.504, p<0.001) with a mean difference of 2.82% in the left ventricular (LV) surface between the two images. Polar maps of transmural cMRI and bipolar maps of NOGA showed significant association for determining of the extent of transmural infarction (r = 0.727, p<0.001, overlap ratio of 81.6±11.1%) and non-transmural infarction (r = 0.555, p<0.001, overlap ratio of 70.6±18.5%). NOGA overestimated the transmural scar size (6.81% of the LV surface) but slightly underestimated the size of the non-transmural infarction (−3.04% of the LV surface). Conclusions By combining unipolar and bipolar voltage maps, NOGA endocardial mapping is useful for accurate delineation of the targeted zone for intramyocardial therapy and is comparable to cMRI-LE. This may be useful

  9. Comparison of NOGA endocardial mapping and cardiac magnetic resonance imaging for determining infarct size and infarct transmurality for intramyocardial injection therapy using experimental data.

    PubMed

    Pavo, Noemi; Jakab, Andras; Emmert, Maximilian Y; Strebinger, Georg; Wolint, Petra; Zimmermann, Matthias; Ankersmit, Hendrik Jan; Hoerstrup, Simon P; Maurer, Gerald; Gyöngyösi, Mariann

    2014-01-01

    We compared the accuracy of NOGA endocardial mapping for delineating transmural and non-transmural infarction to the results of cardiac magnetic resonance imaging (cMRI) with late gadolinium enhancement (LE) for guiding intramyocardial reparative substance delivery using data from experimental myocardial infarction studies. Sixty domestic pigs underwent diagnostic NOGA endocardial mapping and cMRI-LE 60 days after induction of closed-chest reperfused myocardial infarction. The infarct size was determined by LE of cMRI and by delineation of the infarct core on the unipolar voltage polar map. The sizes of the transmural and non-transmural infarctions were calculated from the cMRI transmurality map using signal intensity (SI) cut-offs of>75% and>25% and from NOGA bipolar maps using bipolar voltage cut-off values of <0.8 mV and <1.9 mV. Linear regression analysis and Bland-Altman plots were used to determine correlations and systematic differences between the two images. The overlapping ratios of the transmural and non-transmural infarcted areas were calculated. Infarct size as determined by 2D NOGA unipolar voltage polar mapping correlated with the 3D cMRI-LE findings (r = 0.504, p<0.001) with a mean difference of 2.82% in the left ventricular (LV) surface between the two images. Polar maps of transmural cMRI and bipolar maps of NOGA showed significant association for determining of the extent of transmural infarction (r = 0.727, p<0.001, overlap ratio of 81.6±11.1%) and non-transmural infarction (r = 0.555, p<0.001, overlap ratio of 70.6±18.5%). NOGA overestimated the transmural scar size (6.81% of the LV surface) but slightly underestimated the size of the non-transmural infarction (-3.04% of the LV surface). By combining unipolar and bipolar voltage maps, NOGA endocardial mapping is useful for accurate delineation of the targeted zone for intramyocardial therapy and is comparable to cMRI-LE. This may be useful in patients with contraindications for c

  10. Circumferential graben and the structural evolution of Alba Mons, Mars

    NASA Astrophysics Data System (ADS)

    Öhman, Teemu; McGovern, Patrick J.

    2014-05-01

    Alba Mons is a unique, very extensive but shallow volcanotectonic construct in northern Tharsis, Mars. Numerous models have been presented to explain the formation of Alba Mons and its most characteristic feature, a wristwatch-like pattern of radial and circumferential graben. We used a wide selection of topographic datasets to characterize the fault throw variation on nine topographic transects across the circumferential graben in order to provide observational constraints for the different formation models, and to gain further insight into the evolution of Alba Mons. In most of the transects, summed throws from outwards-facing (away from the center of the volcano) faults are larger than from the inwards-facing (towards the center) ones. Only the very gently sloping western transects show the opposite, emphasizing the east-west-asymmetry of Alba Mons. 10-40% of the observed topographic relief of Alba Mons along the nine transects can be accounted for by this throw difference between the inwards- and outwards-facing faults. These results are consistent with predictions of models suggesting an uplift mechanism to explain the formation of the circumferential graben, but not with models invoking central subsidence. Horizontal extensional strain along the transects varies between 0.5% and 2%, consistent with strain predictions of the late-stage sill complex inflation model of McGovern et al. (McGovern, P.J., Solomon, S.C., Head J.W. III, Smith, D.E., Zuber M.T., Neumann, G.A. [2001]. J. Geophys. Res. 106(E10), 23769-23809).

  11. Improved circumferential shaft seal for aircraft gear transmissions

    NASA Technical Reports Server (NTRS)

    Ludwig, L. P.; Strom, T. N.

    1973-01-01

    Operation under simulated aircraft transmission conditions of speeds to 2850 m/min (9350 ft/min), lubricant temperatures to 394 K (250 F), shaft radial runouts to 0.254 mm (0.010 in.) F.I.R. (full indicator reading), and pressure differentials to 1.03 N/cm2 (1.5 psi) revealed that conventional circumferential seals leaked excessively. Modifying the conventional seal by adding helical grooves to the seal bore reduced leakage rates to within the acceptable level of 10 cm3/hr. The leakage rate of this modified seal was not significantly affected by lubricant flooding or by shaft radial runout.

  12. Esophageal Rings and Stricture Related to a Circumferential Inlet Patch

    PubMed Central

    Scott, Larry

    2016-01-01

    Inlet patches are sometimes seen during upper endoscopy, usually in the proximal esophagus. Complications of inlet patches can cause a wide array of symptoms and complications. A man presented with dysphagia and was found to have 2 rings in the upper esophagus, just above and below a circumferential inlet patch. The more distal ring caused a stenosis, which produced the symptoms. Savary dilation and treatment with a proton pump inhibitor led to symptom resolution. Pathology was missed on the patient's first endoscopy, highlighting the importance of looking for pathology throughout the entire esophagus, not just in the distal esophagus. PMID:27807576

  13. On estimating intraventricular hemodynamic forces from endocardial dynamics: A comparative study with 4D flow MRI.

    PubMed

    Pedrizzetti, Gianni; Arvidsson, Per M; Töger, Johannes; Borgquist, Rasmus; Domenichini, Federico; Arheden, Håkan; Heiberg, Einar

    2017-07-26

    Intraventricular pressure gradients or hemodynamic forces, which are their global measure integrated over the left ventricular volume, have a fundamental importance in ventricular function. They may help revealing a sub-optimal cardiac function that is not evident in terms of tissue motion, which is naturally heterogeneous and variable, and can influence cardiac adaptation. However, hemodynamic forces are not utilized in clinical cardiology due to the unavailability of simple non-invasive measurement tools. Hemodynamic forces depend on the intraventricular flow; nevertheless, most of them are imputable to the dynamics of the endocardial flow boundary and to the exchange of momentum across the mitral and aortic orifices. In this study, we introduce a simplified model based on first principles of fluid dynamics that allows estimating hemodynamic forces without knowing the velocity field inside the LV. The model is validated with 3D phase-contrast MRI (known as 4D flow MRI) in 15 subjects, (5 healthy and 10 patients) using the endocardial surface reconstructed from the three standard long-axis projections. Results demonstrate that the model provides consistent estimates for the base-apex component (mean correlation coefficient r=0.77 for instantaneous values and r=0.88 for root mean square) and good estimates of the inferolateral-anteroseptal component (r=0.50 and 0.84, respectively). The present method represents a potential integration to the existing ones quantifying endocardial deformation in MRI and echocardiography to add a physics-based estimation of the corresponding hemodynamic forces. These could help the clinician to early detect sub-clinical diseases and differentiate between different cardiac dysfunctional states. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Sex differences in venous stenosis and occlusion in patients with endocardial leads.

    PubMed

    Boczar, Krzysztof; Dębski, Maciej; Ząbek, Andrzej; Haberka, Kazimierz; Sławuta, Agnieszka; Lelakowski, Jacek; Małecka, Barbara

    2017-05-23

    Venous stenosis and occlusion (VSO) in the presence of endocardial leads constitute one of the complications of permanent cardiac pacing. At present there are no scientific reports on the influence of sex on the incidence of VSO. The aim of the study was to examine the influence of sex on the incidence of VSO in patients with earlier implanted endocardial leads in a single-center retrospective analysis. The material consists of 284 records of consecutive patients admitted to hospital to undergo electrotherapy procedures. In all patients a contrast venography for ipsilateral venous confluence was performed before the procedure. Patients were divided into two groups according to sex criterion. Groups were compared concerning following parameters: demographic characteristics, cardiac implantable electronic device (CIED) characteristics, comorbidities, CHA2DS2-VASc score, selected risk factors for VSO. Group I consist of 101 females, whereas group II consist of 183 males. Both groups did not differ significantly for age, number of implanted endocardial leads and lead dwell time. In the cohort males were with significantly greater burden of morbidity, reflected by the mean result of CHA2DS2-VASc (P=0.0098). In males there was significantly more often chronic heart failure (P<0.0001), chronic obstructive pulmonary disease (P=0.0450) and tobacco use (P=0.0159). Males had more ICD implanted than females (P=0.0270). In the examine cohort 88 patients (31%) had VSO. There was no statistically significant difference in terms of presence of VSO between females and males (P=0.4685). The detailed analysis of the patients with VSO divided according to sex revealed higher morbidity in males. The equality of VSO incidence in groups of males and females along with the predominance of factors protecting against VSO in group of males support the assumption that female gender is a protective factor against the development of VSO, equally as known protective factors in males.

  15. Retinoic Acid Signaling Is Essential for Valvulogenesis by Affecting Endocardial Cushions Formation in Zebrafish Embryos.

    PubMed

    Li, Junbo; Yue, Yunyun; Zhao, Qingshun

    2016-02-01

    Retinoic acid (RA) plays important roles in many stages of heart morphogenesis. Zebrafish embryos treated with exogenous RA display defective atrio-ventricular canal (AVC) specification. However, whether endogenous RA signaling takes part in cardiac valve formation remains unknown. Herein, we investigated the role of RA signaling in cardiac valve development by knocking down aldh1a2, the gene encoding an enzyme that is mainly responsible for RA synthesis during early development, in zebrafish embryos. The results showed that partially knocking down aldh1a2 caused defective formation of primitive cardiac valve leaflets at 108 hpf (hour post-fertilization). Inhibiting endogenous RA signaling by 4-diethylaminobenzal-dehyde revealed that 16-26 hpf was a key time window when RA signaling affects the valvulogenesis. The aldh1a2 morphants had defective formation of endocardial cushion (EC) at 76 hpf though they had almost normal hemodynamics and cardiac chamber specification at early development. Examining the expression patterns of AVC marker genes including bmp4, bmp2b, nppa, notch1b, and has2, we found the morphants displayed abnormal development of endocardial AVC but almost normal development of myocardial AVC at 50 hpf. Being consistent with the reduced expression of notch1b in endocardial AVC, the VE-cadherin gene cdh5, the downstream gene of Notch signaling, was ectopically expressed in AVC of aldh1a2 morphants at 50 hpf, and overexpression of cdh5 greatly affected the formation of EC in the embryos at 76 hpf. Taken together, our results suggest that RA signaling plays essential roles in zebrafish cardiac valvulogenesis.

  16. Orthogonal electrode catheter array for mapping of endocardial focal site of ventricular activation

    SciTech Connect

    Desai, J.M.; Nyo, H.; Vera, Z.; Seibert, J.A.; Vogelsang, P.J. )

    1991-04-01

    Precise location of the endocardial site of origin of ventricular tachycardia may facilitate surgical and catheter ablation of this arrhythmia. The endocardial catheter mapping technique can locate the site of ventricular tachycardia within 4-8 cm2 of the earliest site recorded by the catheter. This report describes an orthogonal electrode catheter array (OECA) for mapping and radiofrequency ablation (RFA) of endocardial focal site of origin of a plunge electrode paced model of ventricular activation in dogs. The OECA is an 8 F five pole catheter with four peripheral electrodes and one central electrode (total surface area 0.8 cm{sup 2}). In eight mongrel dogs, mapping was performed by arbitrarily dividing the left ventricle (LV) into four segments. Each segment was mapped with OECA to find the earliest segment. Bipolar and unipolar electrograms were obtained. The plunge electrode (not visible on fluoroscopy) site was identified by the earliest wave front arrival times of -30 msec or earlier at two or more electrodes (unipolar electrograms) with reference to the earliest recorded surface ECG (I, AVF, and V1). Validation of the proximity of the five electrodes of the OECA to the plunge electrode was performed by digital radiography and RFA. Pathological examination was performed to document the proximity of the OECA to the plunge electrode and also for the width, depth, and microscopic changes of the ablation. To find the segment with the earliest LV activation a total of 10 {plus minus} 3 (mean {plus minus} SD) positions were mapped. Mean arrival times at the two earlier electrodes were -39 {plus minus} 4 msec and -35 {plus minus} 3 msec. Digital radiography showed the plunge electrode to be within the area covered by all five electrodes in all eight dogs. The plunge electrode was within 1 cm2 area of the region of RFA in all eight dogs.

  17. Endocardial substrate mapping for monomorphic ventricular tachycardia ablation in ischemic and non-ischemic cardiomyopathy.

    PubMed

    Fukuzawa, Koji; Yoshida, Akihiro; Kubo, Shinya; Takano, Takatsugu; Kiuchi, Kunihiko; Kanda, Gaku; Takami, Kaoru; Kumagai, Hiroyuki; Torii, Satoko; Takami, Mitsuru; Yokoyama, Mitsuhiro; Hirata, Ken-ichi

    2008-07-18

    We investigated the differences in the endocardial substrates between ischemic cardiomyopathy (ICM) and non-ICM (NICM) by using electro-anatomical mapping and pace-mapping. We studied 18 patients (ICM and NICM, 9 each) with monomorphic ventricular tachycardia (VT) documented by 12-leads ECG. Low voltage area was defined by signal amplitude <1.5 mV. A pace-map QRS morphology that matched VT in >10 of the 12-leads ECG was regarded as a pace-map match. And conduction delay during pace-mapping was defined as the stimulus to QRS interval >or=40 ms. Low voltage area was 53.8 +/- 21.5 and 20.8 +/- 16.7 cm2 in ICM and NICM patients, respectively (P = 0.002). Pace-mapping was assessed in 6 ICM and 9 NICM. Pace-map match with conduction delay were obtained in all the 6 ICM patients. But in NICM patients, pace-map match with conduction delay was obtained in 3 patients. Pace-map match sites where conduction delay was not observed were obtained in 5 patients. Pace-map match could not be obtained in 1 patient. We attempted ablation in 6 ICM and 7 NICM patients. Subsequently, VT recurrence was not observed in ICM but it was observed in 6 of 7 NICM patients (log-rank P = 0.0016). In NICM patients, the arrhythmogenic substrate that represented the abnormal electrogram and conduction delay was observed less within the endocardial surface when compared with that observed in ICM. VT recurrence rate subsequent to endocardial ablation was higher in NICM than in ICM patients.

  18. Endocardial Cushion Morphogenesis and Coronary Vessel Development Require Chicken Ovalbumin Upstream Promoter-Transcription Factor II

    PubMed Central

    Lin, Fu-Jung; You, Li-Ru; Yu, Cheng-Tai; Hsu, Wen-Hsin; Tsai, Ming-Jer; Tsai, Sophia Y.

    2013-01-01

    Objective Septal defects and coronary vessel anomalies are common congenital heart defects, yet their ontogeny and the underlying genetic mechanisms are not well understood. Here, we investigated the role of chicken ovalbumin upstream promoter-transcription factor II (COUP-TFII, NR2F2) in cardiac organogenesis. Methods and Results We analyzed embryos deficient in COUP-TFII and observed a spectrum of cardiac defects, including atrioventricular septal defect, thin-walled myocardium, and abnormal coronary morphogenesis. We show by expression analysis that COUP-TFII is expressed in the endocardium and the epicardium but not in the myocardium of the ventricle. Using endothelial-specific COUP-TFII mutants and molecular approaches, we show that COUP-TFII deficiency resulted in endocardial cushion hypoplasia. This was attributed to the reduced growth and survival of atrioventricular cushion mesenchymal cells and defective epithelial-mesenchymal transformation (EMT) in the underlying endocardium. In addition, the endocardial EMT defect was accompanied by downregulation of Snai1, one of the master regulators of EMT, and upregulation of vascular endothelial-cadherin. Furthermore, we show that although COUP-TFII does not play a major role in the formation of epicardial cell cysts, it is critically important for the formation of epicardium. Ablation of COUP-TFII impairs epicardial EMT and coronary plexus formation. Conclusion Our results reveal that COUP-TFII plays cell-autonomous roles in the endocardium and the epicardium for endocardial and epicardial EMT, which are required for proper valve and coronary vessel formation during heart development. PMID:22962329

  19. Single-Beat Noninvasive Imaging of Ventricular Endocardial and Epicardial Activation in Patients Undergoing CRT

    PubMed Central

    Berger, Thomas; Pfeifer, Bernhard; Hanser, Friedrich F.; Hintringer, Florian; Fischer, Gerald; Netzer, Michael; Trieb, Thomas; Stuehlinger, Markus; Dichtl, Wolfgang; Baumgartner, Christian; Pachinger, Otmar; Seger, Michael

    2011-01-01

    Background Little is known about the effect of cardiac resynchronization therapy (CRT) on endo- and epicardial ventricular activation. Noninvasive imaging of cardiac electrophysiology (NICE) is a novel imaging tool for visualization of both epi- and endocardial ventricular electrical activation. Methodology/Principal Findings NICE was performed in ten patients with congestive heart failure (CHF) undergoing CRT and in ten patients without structural heart disease (control group). NICE is a fusion of data from high-resolution ECG mapping with a model of the patient's individual cardiothoracic anatomy created from magnetic resonance imaging. Beat-to-beat endocardial and epicardial ventricular activation sequences were computed during native rhythm as well as during ventricular pacing using a bidomain theory-based heart model to solve the related inverse problem. During right ventricular (RV) pacing control patients showed a deterioration of the ventricular activation sequence similar to the intrinsic activation pattern of CHF patients. Left ventricular propagation velocities were significantly decreased in CHF patients as compared to the control group (1.6±0.4 versus 2.1±0.5 m/sec; p<0.05). CHF patients showed right-to-left septal activation with the latest activation epicardially in the lateral wall of the left ventricle. Biventricular pacing resulted in a resynchronization of the ventricular activation sequence and in a marked decrease of total LV activation duration as compared to intrinsic conduction and RV pacing (129±16 versus 157±28 and 173±25 ms; both p<0.05). Conclusions/Significance Endocardial and epicardial ventricular activation can be visualized noninvasively by NICE. Identification of individual ventricular activation properties may help identify responders to CRT and to further improve response to CRT by facilitating a patient-specific lead placement and device programming. PMID:21298045

  20. Association between High Endocardial Unipolar Voltage and Improved Left Ventricular Function in Patients with Ischemic Cardiomyopathy

    PubMed Central

    Park, Ki; Lai, Dejian; Handberg, Eileen M.; Perin, Emerson C.; Pepine, Carl J.; Anderson, R. David

    2016-01-01

    We know that endocardial mapping reports left ventricular electrical activity (voltage) and that these data can predict outcomes in patients undergoing traditional revascularization. Because the mapping data from experimental models have also been linked with myocardial viability, we hypothesized an association between increased unipolar voltage in patients undergoing intramyocardial injections and their subsequent improvement in left ventricular performance. For this exploratory analysis, we evaluated 86 patients with left ventricular dysfunction, heart-failure symptoms, possible angina, and no revascularization options, who were undergoing endocardial mapping. Fifty-seven patients received bone marrow mononuclear cell (BMC) injections and 29 patients received cell-free injections of a placebo. The average mapping site voltage was 9.7 ± 2 mV, and sites with voltage of ≥6.9 mV were engaged by needle and injected (with BMC or placebo). For all patients, at 6 months, left ventricular ejection fraction (LVEF) improved, and after covariate adjustment this improvement was best predicted by injection-site voltage. For every 2-mV increase in baseline voltage, we detected a 1.3 increase in absolute LVEF units for all patients (P=0.038). Multiple linear regression analyses confirmed that voltage and the CD34+ count present in bone marrow (but not treatment assignment) were associated with improved LVEF (P=0.03 and P=0.014, respectively). In an exploratory analysis, higher endocardial voltage and bone marrow CD34+ levels were associated with improved left ventricular function among ischemic cardiomyopathy patients. Intramyocardial needle injections, possibly through stimulation of angiogenesis, might serve as a future therapy in patients with reduced left ventricular function and warrants investigation. PMID:27547135

  1. Improvement of Right Ventricular Hemodynamics with Left Ventricular Endocardial Pacing during Cardiac Resynchronization Therapy

    PubMed Central

    HYDE, EOIN R.; BEHAR, JONATHAN M.; CROZIER, ANDREW; CLARIDGE, SIMON; JACKSON, TOM; SOHAL, MANAV; GILL, JASWINDER S.; O'NEILL, MARK D.; RAZAVI, REZA; RINALDI, CHRISTOPHER A.

    2016-01-01

    Background Cardiac resynchronization therapy (CRT) with biventricular epicardial (BV‐CS) or endocardial left ventricular (LV) stimulation (BV‐EN) improves LV hemodynamics. The effect of CRT on right ventricular function is less clear, particularly for BV‐EN. Our objective was to compare the simultaneous acute hemodynamic response (AHR) of the right and left ventricles (RV and LV) with BV‐CS and BV‐EN in order to determine the optimal mode of CRT delivery. Methods Nine patients with previously implanted CRT devices successfully underwent a temporary pacing study. Pressure wires measured the simultaneous AHR in both ventricles during different pacing protocols. Conventional epicardial CRT was delivered in LV‐only (LV‐CS) and BV‐CS configurations and compared with BV‐EN pacing in multiple locations using a roving decapolar catheter. Results Best BV‐EN (optimal AHR of all LV endocardial pacing sites) produced a significantly greater RV AHR compared with LV‐CS and BV‐CS pacing (P < 0.05). RV AHR had a significantly increased standard deviation compared to LV AHR (P < 0.05) with a weak correlation between RV and LV AHR (Spearman rs = −0.06). Compromised biventricular optimization, whereby RV AHR was increased at the expense of a smaller decrease in LV AHR, was achieved in 56% of cases, all with BV‐EN pacing. Conclusions BV‐EN pacing produces significant increases in both LV and RV AHR, above that achievable with conventional epicardial pacing. RV AHR cannot be used as a surrogate for optimizing LV AHR; however, compromised biventricular optimization is possible. The beneficial effect of endocardial LV pacing on RV function may have important clinical benefits beyond conventional CRT. PMID:27001004

  2. Endocardial fibroelastosis in L-transposition of the great arteries with Ebstein's anomaly: revisited.

    PubMed

    Dahdah, N S; van Doesburg, N H; Russo, P

    1998-01-01

    Ebstein's anomaly is a congenital deformity of the tricuspid valve consisting mainly of leaflet malinsertion. Clinical presentation varies from asymptomatic patients to those with congestive heart failure secondary to significant valvular regurgitation and low right ventricular output. We report here the case of an infant with a diagnosis of corrected transposition of the great arteries and Ebstein's deformity of the left-sided tricuspid valve who developed pulmonary hypertension and endocardial fibroelastosis, two unusual associations with this lesion. We also discuss the pathophysiology of this association and related literature.

  3. Relationship-Based Care for Newborns With Down Syndrome and Endocardial Cushion Defect.

    PubMed

    Phillips, Cathi; Boyd, Margaret

    2015-01-01

    Down syndrome with endocardial cushion defect is a challenging diagnosis for parents as well as members of the health care team. Utilizing a framework of relationship-based care, nurses are in a position to positively affect parents' experience by providing education, advocacy, and support from initial diagnosis through discharge. The plan of care is multidisciplinary and focuses on critical developmental needs, such as bonding and feeding. Because Down syndrome is associated with multiple anomalies, anticipatory guidance is needed to assist parents with establishing a health maintenance plan for their child after discharge. © 2015 AWHONN.

  4. Left Ventricular Myocardial Segmentation in 3-D Ultrasound Recordings: Effect of Different Endocardial and Epicardial Coupling Strategies.

    PubMed

    Pedrosa, Joao; Barbosa, Daniel; Heyde, Brecht; Schnell, Frederic; Rosner, Assami; Claus, Piet; D'hooge, Jan

    2017-03-01

    Cardiac volume/function assessment remains a critical step in daily cardiology, and 3-D ultrasound plays an increasingly important role. Though development of automatic endocardial segmentation methods has received much attention, the same cannot be said about epicardial segmentation, in spite of the importance of full myocardial segmentation. In this paper, different ways of coupling the endocardial and epicardial segmentations are contrasted and compared with uncoupled segmentation. For this purpose, the B-spline explicit active surfaces framework was used; 27 3-D echocardiographic images were used to validate the different coupling strategies, which were compared with manual contouring of the endocardial and epicardial borders performed by an expert. It is shown that an independent segmentation of the endocardium followed by an epicardial segmentation coupled to the endocardium is the most advantageous. In this way, a framework for fully automatic 3-D myocardial segmentation is proposed using a novel coupling strategy.

  5. Loss of muscleblind-like 1 promotes invasive mesenchyme formation in endocardial cushions by stimulating autocrine TGFβ3

    PubMed Central

    2012-01-01

    Background Valvulogenesis and septation in the developing heart depend on the formation and remodeling of endocardial cushions in the atrioventricular canal (AVC) and outflow tract (OFT). These cushions are invaded by a subpopulation of endocardial cells that undergo an epithelial-mesenchymal transition in response to paracrine and autocrine transforming growth factor β (TGFβ) signals. We previously demonstrated that the RNA binding protein muscleblind-like 1 (MBNL1) is expressed specifically in the cushion endocardium, and knockdown of MBNL1 in stage 14 embryonic chicken AVC explants enhances TGFβ-dependent endocardial cell invasion. Results In this study, we demonstrate that the effect of MBNL1 knockdown on invasion remains dependent on TGFβ3 after it is no longer required to induce basal levels of invasion. TGFβ3, but not TGFβ2, levels are elevated in medium conditioned by MBNL1-depleted AVC explants. TGFβ3 is elevated even when the myocardium is removed, indicating that MBNL1 modulates autocrine TGFβ3 production in the endocardium. More TGFβ3-positive cells are observed in the endocardial monolayer following MBNL1 knockdown. Addition of exogenous TGFβ3 to AVC explants recapitulates the effects of MBNL1 knockdown. Time course experiments demonstrate that knockdown of MBNL1 induces precocious TGFβ3 secretion, and early exposure to excess TGFβ3 induces precocious invasion. MBNL1 expression precedes TGFβ3 in the AVC endocardium, consistent with a role in preventing precocious autocrine TGFβ3 signaling. The stimulatory effects of MBNL1 knockdown on invasion are lost in stage 16 AVC explants. Knockdown of MBNL1 in OFT explants similarly enhances cell invasion, but not activation. TGFβ is necessary and sufficient to mediate this effect. Conclusions Taken together, these data support a model in which MBNL1 negatively regulates cell invasion in the endocardial cushions by restricting the magnitude and timing of endocardial-derived TGFβ3 production. PMID

  6. J-integral of circumferential crack in large diameter pipes

    SciTech Connect

    Ji, Wei; Chao, Yuh J.; Sutton, M.A. . Dept. of Mechanical Engineering); Lam, P.S.; Mertz, G.E. )

    1992-01-01

    Large diameter thin-walled pipes are encountered in low pressure nuclear power piping system. Fracture parameters such as K and J, associated with postulated cracks are needed to assess the safety of the structure, for example, prediction of the onset of tile crack growth and the stability of the crack. The Electric Power Research Institute (EPRI) has completed a comprehensive study of cracks in pipes and handbook-type data is available. However, for some large diameter, thin-walled pipes the needed information is not included in the handbook. This paper reports our study of circumferential cracks in large diameter, thin-walled pipes (R/t=30 to 40) under remote bending or tension loads. Elastic-Plastic analyses using finite element method were performed to determine the elastic and fully plastic J values for various pipe/crack geometries. A non-linear Ramberg-Osgood material model is used, with strain hardening exponents(n) ranging from 3 to 10. A number of circumferential, through thickness cracks were studied with half crack angles ranging from 0.063[pi] to 0.5[pi]. Results are tabulated for use with the EPRI estimation scheme.

  7. J-integral of circumferential crack in large diameter pipes

    SciTech Connect

    Ji, Wei; Chao, Yuh J.; Sutton, M.A.; Lam, P.S.; Mertz, G.E.

    1992-12-01

    Large diameter thin-walled pipes are encountered in low pressure nuclear power piping system. Fracture parameters such as K and J, associated with postulated cracks are needed to assess the safety of the structure, for example, prediction of the onset of tile crack growth and the stability of the crack. The Electric Power Research Institute (EPRI) has completed a comprehensive study of cracks in pipes and handbook-type data is available. However, for some large diameter, thin-walled pipes the needed information is not included in the handbook. This paper reports our study of circumferential cracks in large diameter, thin-walled pipes (R/t=30 to 40) under remote bending or tension loads. Elastic-Plastic analyses using finite element method were performed to determine the elastic and fully plastic J values for various pipe/crack geometries. A non-linear Ramberg-Osgood material model is used, with strain hardening exponents(n) ranging from 3 to 10. A number of circumferential, through thickness cracks were studied with half crack angles ranging from 0.063{pi} to 0.5{pi}. Results are tabulated for use with the EPRI estimation scheme.

  8. Complete 360° circumferential SSOCT gonioscopy of the iridocorneal angle

    NASA Astrophysics Data System (ADS)

    McNabb, Ryan P.; Kuo, Anthony N.; Izatt, Joseph A.

    2014-02-01

    The ocular iridocorneal angle is generally an optically inaccessible area when viewed directly through the cornea due to the high angle of incidence required and the large index of refraction difference between air and cornea (nair = 1.000 and ncornea = 1.376) resulting in total internal reflection. Gonioscopy allows for viewing of the angle by removing the aircornea interface through the use of a special contact lens on the eye. Gonioscopy is used clinically to visualize the angle directly but only en face. Optical coherence tomography (OCT) has been used to image the angle and deeper structures via an external approach. Typically, this imaging technique is performed by utilizing a conventional anterior segment OCT scanning system. However, instead of imaging the apex of the cornea, either the scanner or the subject is tilted such that the corneoscleral limbus is orthogonal to the optical axis of the scanner requiring multiple volumes to obtain complete circumferential coverage of the ocular angle. We developed a novel gonioscopic OCT (GOCT) system that images the entire ocular angle within a single volume via an "internal" approach through the use of a custom radially symmetric gonioscopic contact lens. We present, to our knowledge, the first complete 360° circumferential volumes of the iridocorneal angle from a direct, internal approach.

  9. J-integral of circumferential crack in large diameter pipes

    NASA Astrophysics Data System (ADS)

    Ji, Wei; Chao, Yuh J.; Sutton, M. A.; Lam, P. S.; Mertz, G. E.

    Large diameter thin-walled pipes are encountered in a low pressure nuclear power piping system. Fracture parameters such as K and J, associated with postulated cracks, are needed to assess the safety of the structure, for example, prediction of the onset of tile crack growth and the stability of the crack. The Electric Power Research Institute (EPRI) has completed a comprehensive study of cracks in pipes and handbook-type data is available. However, for some large diameter, thin-walled pipes the needed information is not included in the handbook. This paper reports our study of circumferential cracks in large diameter, thin-walled pipes (R/t=30 to 40) under remote bending or tension loads. Elastic-Plastic analyses using the finite element method were performed to determine the elastic and fully plastic J values for various pipe/crack geometries. A non-linear Ramberg-Osgood material model is used with strain hardening exponents (n) that range from 3 to 10. A number of circumferential, through thickness cracks were studied with half crack angles ranging from 0.063(pi) to 0.5(pi). Results are tabulated for use with the EPRI estimation scheme.

  10. Circumferential intradural meningioma of the thoracic spinal cord.

    PubMed

    Foster, Mitchell; Soh, Calvin; DuPlessis, Daniel; Karabatsou, Konstantina

    2016-07-01

    There are very few reported cases of a meningioma circumferentially surrounding the spinal cord. To date, this entity has only been described at the conus medullaris and in the cervical cord. Herewith, the authors describe a case of an intradural extramedullary meningioma that completely encircled the thoracic spinal cord. A 40-year-old woman with progressive numbness of the lower limbs and spasticity of gait following a fall presented to our hospital. Magnetic resonance imaging of the spine demonstrated an abnormality at T6-T7 completely encircling the spinal cord. The patient underwent a T6-T8 laminectomy and subtotal resection of the intradural partially calcified lesion. Resection of the anterolateral portion was not feasible. Histology revealed psammomatous meningioma (WHO Grade 1). The patient recovered well and was discharged with improved gait but some residual numbness of her feet and right hemithorax. This is the first reported case of an intradural extramedullary meningioma completely encircling the thoracic spinal cord. Achieving complete resection of this circumferential meningioma was not possible via a posterior approach. The optimum management of this condition is unknown; clearly, achieving symptomatic relief with adequate cord decompression is paramount; however, the long-term outcome and risk of recurrence in these cases, given their rarity and the difficulties in achieving complete resection, is unknown. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Usefulness of atrial deformation analysis to predict left atrial fibrosis and endocardial thickness in patients undergoing mitral valve operations for severe mitral regurgitation secondary to mitral valve prolapse.

    PubMed

    Cameli, Matteo; Lisi, Matteo; Righini, Francesca Maria; Massoni, Alberto; Natali, Benedetta Maria; Focardi, Marta; Tacchini, Damiana; Geyer, Alessia; Curci, Valeria; Di Tommaso, Cristina; Lisi, Gianfranco; Maccherini, Massimo; Chiavarelli, Mario; Massetti, Massimo; Tanganelli, Piero; Mondillo, Sergio

    2013-02-15

    In patients with severe mitral regurgitation (MR) referred for cardiac surgery, left atrial (LA) remodeling and enlargement are accompanied by mechanical stress, mediated cellular hypertrophy, and interstitial fibrosis that finally lead to LA failure. Speckle tracking echocardiography is a novel non-Doppler-based method that allows an objective quantification of LA myocardial deformation, becoming useful for LA functional analysis. We conducted a study to evaluate the relation between the traditional and novel atrial indexes and the extent of ultrastructural alterations, obtained from patients with severe MR who were undergoing surgical correction of the valvular disease. The study population included 46 patients with severe MR, referred to our echocardiographic laboratory for a diagnostic examination before cardiac surgery. The global peak atrial longitudinal strain (PALS) was measured in all subjects by averaging all atrial segments. LA tissue samples were obtained from all patients. Masson's trichrome staining was performed to assess the extent of the fibrosis. The LA endocardial thickness was measured. A close negative correlation between the global PALS and grade of LA myocardial fibrosis was found (r = -0.82, p <0.0001), with poorer correlations for the LA indexed volume (r = 0.51, p = 0.01), LA ejection fraction (r = 0.61, p = 0.005), and E/E' ratio (0.14, p = NS). Of these indexes, global PALS showed the best diagnostic accuracy to detect LA fibrosis (area under the curve 0.89), and it appears to be a strong and independent predictor of LA fibrosis. Furthermore, we also demonstrated an inverse correlation between the global PALS and LA endocardial thickness (r = -0.66, p = 0.0001). In conclusion, in patients with severe MR referred for cardiac surgery, impairment of LA longitudinal deformation, as assessed by the global PALS, correlated strongly with the extent of LA fibrosis and remodeling. Copyright © 2013 Elsevier Inc. All rights reserved.

  12. Characterization of mechanical and geometrical properties of a tube with axial and circumferential guided waves.

    PubMed

    Yeh, Cheng-Hung; Yang, Che-Hua

    2011-05-01

    Guided waves propagating in cylindrical tubes are frequently applied for the characterization of material or geometrical properties of tubes. In a tube, guided waves can propagate in the axial direction and called axial guided waves, or in the circumferential direction called circumferential guided waves. Dispersion spectra for the axial and circumferential guided waves share some common behaviors and however exhibit some particular behaviors of their own. This study provides an investigation with theoretical modeling, experimental measurements, and a simplex-based inversion procedure to explore the similarity and difference between the axial guided waves and circumferential guided waves, aiming at providing useful information while axial and circumferential guided waves are applied in the area of material characterization. The sensitivity to the radius curvature for the circumferential guided waves dispersion spectra is a major point that makes circumferential guided waves different from axial guided waves. For the purpose of material characterization, both axial and circumferential guided waves are able to extract an elastic moduli and wall-thickness information from the dispersion spectra, however, radius information can only be extracted from the circumferential guided waves spectra. Copyright © 2010 Elsevier B.V. All rights reserved.

  13. Stresses and deformations in composite tubes due to a circumferential temperature gradient

    NASA Technical Reports Server (NTRS)

    Hyer, M. W.; Cooper, D. E.

    1986-01-01

    A linear elasticity solution for determining the response of composite tubes subjected to a circumferential temperature gradient is presented. Numerical examples are used to show that, in a single layer tube, fiber orientation strongly influences response. When the fibers are aligned axially, all stress components in the tube are small. When the fibers are aligned circumferentially, the hoop stress becomes large. This difference in behavior is due to the large difference between the radial and circumferential coefficients of thermal expansion when the fibers are oriented circumferentially. In multilayer tubes, stresses are quite high and just two constants characterize the overall bending and axial deformations of the tubes.

  14. Packaging of implantable accelerometers to monitor epicardial and endocardial wall motion.

    PubMed

    Brancato, Luigi; Weydts, Tristan; Oosterlinck, Wouter; Herijgers, Paul; Puers, Robert

    2017-09-01

    Acceleration signals, collected from the inner and the outer heart wall, offer a mean of assessing cardiac function during surgery. Accelerometric measurements can also provide detailed insights into myocardial motion during exploratory investigations. Two different implantable accelerometers to respectively record endocardial and epicardial vibrations, have been developed by packaging a commercially available capacitive transducer. The same coating materials have been deposited on the two devices to ensure biocompatibility of the implants: Parylene-C, medical epoxy and Polydimethylsiloxane (PDMS). The different position-specific requirements resulted in two very dissimilar sensor assemblies. The endocardial accelerometer, that measures accelerations from the inner surface of the heart during acute animal tests, is a 2 mm-radius hemisphere fixed on a polymethyl methacrylate (PMMA) rod to be inserted through the heart wall. The epicardial accelerometer, that monitors the motion of the outer surface of the heart, is a three-legged structure with a stretchable polytetrafluoroethylene (PTFE) reinforcement. This device can follow the continuous motion of the myocardium (the muscular tissue of the heart) during the cardiac cycle, without hindering its natural movement. Leakage currents lower than 1 μA have been measured during two weeks of continuous operation in saline. Both transducers have been used, during animal tests, to simultaneously record and compare acceleration signals from corresponding locations on the inner and the outer heart wall of a female sheep.

  15. Disruption of pdgfra alters endocardial and myocardial fusion during zebrafish cardiac assembly

    PubMed Central

    El-Rass, Suzan; Eisa-Beygi, Shahram; Khong, Edbert; Brand-Arzamendi, Koroboshka; Mauro, Antonio; Zhang, Haibo; Clark, Karl J.; Ekker, Stephen C.

    2017-01-01

    ABSTRACT Cardiac development in vertebrates is a finely tuned process regulated by a set of conserved signaling pathways. Perturbations of these processes are often associated with congenital cardiac malformations. Platelet-derived growth factor receptor α (PDGFRα) is a highly conserved tyrosine kinase receptor, which is essential for development and organogenesis. Disruption of Pdgfrα function in murine models is embryonic lethal due to severe cardiovascular defects, suggesting a role in cardiac development, thus necessitating the use of alternative models to explore its precise function. In this study, we generated a zebrafish pdgfra mutant line by gene trapping, in which the Pdgfra protein is truncated and fused with mRFP (Pdgfra-mRFP). Our results demonstrate that pdgfra mutants have defects in cardiac morphology as a result of abnormal fusion of myocardial precursors. Expression analysis of the developing heart at later stages suggested that Pdgfra-mRFP is expressed in the endocardium. Further examination of the endocardium in pdgfra mutants revealed defective endocardial migration to the midline, where cardiac fusion eventually occurs. Together, our data suggests that pdgfra is required for proper medial migration of both endocardial and myocardial precursors, an essential step required for cardiac assembly and development. PMID:28167492

  16. Disruption of pdgfra alters endocardial and myocardial fusion during zebrafish cardiac assembly.

    PubMed

    El-Rass, Suzan; Eisa-Beygi, Shahram; Khong, Edbert; Brand-Arzamendi, Koroboshka; Mauro, Antonio; Zhang, Haibo; Clark, Karl J; Ekker, Stephen C; Wen, Xiao-Yan

    2017-03-15

    Cardiac development in vertebrates is a finely tuned process regulated by a set of conserved signaling pathways. Perturbations of these processes are often associated with congenital cardiac malformations. Platelet-derived growth factor receptor α (PDGFRα) is a highly conserved tyrosine kinase receptor, which is essential for development and organogenesis. Disruption of Pdgfrα function in murine models is embryonic lethal due to severe cardiovascular defects, suggesting a role in cardiac development, thus necessitating the use of alternative models to explore its precise function. In this study, we generated a zebrafish pdgfra mutant line by gene trapping, in which the Pdgfra protein is truncated and fused with mRFP (Pdgfra-mRFP). Our results demonstrate that pdgfra mutants have defects in cardiac morphology as a result of abnormal fusion of myocardial precursors. Expression analysis of the developing heart at later stages suggested that Pdgfra-mRFP is expressed in the endocardium. Further examination of the endocardium in pdgfra mutants revealed defective endocardial migration to the midline, where cardiac fusion eventually occurs. Together, our data suggests that pdgfra is required for proper medial migration of both endocardial and myocardial precursors, an essential step required for cardiac assembly and development.

  17. Endocardial Lead Extraction in the Polish Registry – clinical practice versus current Heart Rhythm Society consensus

    PubMed Central

    Kutarski, Andrzej; Mitkowski, Przemysław; Przybylski, Andrzej; Lewek, Joanna; Małecka, Barbara; Smukowski, Tomasz; Maciąg, Aleksander; Śmigielski, Janusz

    2013-01-01

    Introduction Over the last 10 years, there has been an increasing number of patients with pacemaker (PM) and cardioverter-defibrillator (ICD). This study is a retrospective analysis of indications for endocardial pacemaker and ICD lead extractions between 2003 and 2009 based on the experience of three Polish Referral Lead Extraction Centers. Material and methods Since 2003, the authors have consecutively retrospectively collected all cases and entered the information in the database. All patients which had indication for lead extraction according to Heart Rhythm Society Guidelines were included to final analyze. Between 2003 and 2005, the data were analyzed together. Since 2006, data have been collected and analyzed annually. Results In each year, a significant increase in lead extraction was observed. The main indications for LE were infections in 52.4% of patients. Nonfunctioning lead extraction constituted the second group of indications for LE in 29.7% of patients. During the registry period, the percentage of class I indications decreased from 80% in 2006 to only 47% in 2009. On the other hand, increasingly more leads were removed because of class 2, especially class 2b. In 2009, 40% of leads were extracted due to class 2b. Conclusions Polish Registry of Endocardial Lead Extraction 2003-2009, shows an increasing frequency of lead extraction. The main indication for LE is infection: systemic and pocket. An increase in class 2, especially 2b, LE indication in every center during the study period was found. PMID:24904658

  18. Hurricane Matthew overwash extents

    USGS Publications Warehouse

    Doran, Kara; Long, Joseph W.; Birchler, Justin; Range, Ginger

    2017-01-01

    The National Assessment of Coastal Change Hazards project exists to understand and predict storm impacts to our nation's coastlines. This data defines the alongshore extent of overwash deposits attributed to coastal processes during Hurricane Matthew.

  19. Transient thermal stress problem for a circumferentially cracked hollow cylinder

    NASA Technical Reports Server (NTRS)

    Nied, H. F.; Erdogan, F.

    1983-01-01

    The paper is concerned with the transient thermal stress problem for a long hollow circular cylinder containing an internal axisymmetric circumferential edge crack that is suddenly cooled from inside. It is assumed that the transient thermal stress problem is quasi-static, i.e., the inertial effects are negligible. Also, all thermoelastic coupling effects and the possible temperature dependence of the thermoelastic constants are neglected. The problem is considered in two parts. The first part is the evaluation of transient thermal stresses in an uncracked cylinder; the second part is the isothermal perturbation problem for the cracked cylinder in which the crack surface tractions, equal and opposite to the thermal stresses obtained from the first problem, are the only external loads. The superposition of the two solutions gives results for the cracked cylinder.

  20. Transient thermal stress problem for a circumferentially cracked hollow cylinder

    NASA Technical Reports Server (NTRS)

    Nied, H. F.; Erdogan, F.

    1982-01-01

    The transient thermal stress problem for a hollow elasticity cylinder containing an internal circumferential edge crack is considered. It is assumed that the problem is axisymmetric with regard to the crack geometry and the loading, and that the inertia effects are negligible. The problem is solved for a cylinder which is suddenly cooled from inside. First the transient temperature and stress distributions in an uncracked cylinder are calculated. By using the equal and opposite of this thermal stress as the crack surface traction in the isothermal cylinder the crack problem is then solved and the stress intensity factor is calculated. The numerical results are obtained as a function of the Fourier number tD/b(2) representing the time for various inner-to-outer radius ratios and relative crack depths, where D and b are respectively the coefficient of diffusivity and the outer radius of the cylinder.

  1. Transverse shear effect in a circumferentially cracked cylindrical shell

    NASA Technical Reports Server (NTRS)

    Delale, F.; Erdogan, F.

    1979-01-01

    The objectives of the paper are to solve the problem of a circumferentially-cracked cylindrical shell by taking into account the effect of transverse shear, and to obtain the stress intensity factors for the bending moment as well as the membrane force as the external load. The formulation of the problem is given for a specially orthotropic material within the framework of a linearized shallow shell theory. The particular theory used permits the consideration of all five boundary conditions as to moment and stress resultants on the crack surface. The effect of Poisson's ratio on the stress intensity factors and the nature of the out-of-plane displacement along the edges of the crack, i.e., bulging, are also studied.

  2. Extended posterior circumferential approach to thoracic and thoracolumbar spine.

    PubMed

    Sundararaj, Gabriel D; Venkatesh, Krishnan; Babu, Parasa Narendra; Amritanand, Rohit

    2009-09-01

    Posterior spinal surgical approach to achieve a retropleural/ retroperitoneal corpectomy with circumferential spinal cord decompression following subtotal vertebrectomy, posterior instrumentation and interbody spacer placement under compression as well as kyphosis correction with spinal column shortening. Infective, traumatic or neoplastic lesions of the vertebral body that lead to vertebral body destruction, instability and neurologic deficit. Need for immediate postoperative loading stability to permit ambulation and rehabilitation. Multiple contiguous vertebral disease. Instances where the graft bed preparation and stable interbody spacer placement may be suboptimal due to the limited access offered by this approach. Posterior midline exposure two to three levels above and below lesion, dissection at level of lesion extended bilaterally exposing transverse processes, costotransverse articulations and medial 5-8 cm of ribs. Placement of pedicle screws at proximal and distal levels; in case of osteoporotic bone augment screws with cement. Bilateral costotransversectomy at one or more levels to drain prevertebral abscess and expose diseased vertebral bodies. After temporary stabilization, laminectomy and corpectomy are carried out from both sides to permit circumferential decompression. A temporary rod is placed on the contralateral side in the position of deformity to prevent any inadvertent translatory movements during the subsequent surgical step. After completion of the procedure an appropriately contoured rod is placed. The interbody spacer is positioned. Kyphosis correction by spinal column shortening and compression along the posterior implant is performed. By day 3 ambulation and rehabilitation are initiated. 22 patients were operated in the last 8 years with tuberculosis (18 patients - twelve paraplegics), osteoporotic fractures (two patients), congenital kyphosis and Ewing's sarcoma (one patient each). All patients were followed up at 3, 6, 9, and 12

  3. [Effects of prolonged endocardial stimulation on left ventricular mechanical synchrony. A pilot study applying gated-SPECT phase analysis. Endocardial stimulation and dyssynchrony].

    PubMed

    Ferrando-Castagnetto, Federico; Ricca-Mallada, Roberto; Vidal, Alejandro; Ferrando, Rodolfo

    2017-01-25

    To evaluate left ventricular mechanical dyssynchrony (LVMD) associated to prolonged right ventricular pacing through an innovative imaging technique, as a pilot study in Uruguay. We performed 99mTc-MIBI gated-SPECT and phase analysis in 12 patients with pacemakers implanted at least one year before scintigraphy due to advanced atrioventricular block. Clinical data, QRS duration, rate, mode and site of pacing in right ventricle, chamber diameters, presence and extension of myocardial scar and ischemia and rest LVEF were recorded. Using V-Sync of Emory Cardiac Toolbox we obtained standard deviation (PSD) and bandwidth (PBW) from rest phase histogram and then we compared these indexes with controls in the subgroups of patients with LVEF≥and<50%. Patients with prolonged RV endocardial pacing exhibited marked LVMD. More severe dyssynchrony was found in patients with impaired LVEF than in patients with preserved LVEF (PSD: 46.67(o) vs. 26.81(o), P<.05; PBW: 144.33(o) vs. 77.41(o), P<.05). Higher left ventricle diameters, extensive infarct or significant ischemia were found in patients with impaired LVEF. Chronic right ventricular pacing was invariably associated with LVMD, even when systolic function was preserved. Phase analysis could be a potentially useful technique to evaluate LMVD associated with myocardial scar in patients with pacemanker and to decide promptly the upgrading to biventricular pacing. Copyright © 2016 Instituto Nacional de Cardiología Ignacio Chávez. Publicado por Masson Doyma México S.A. All rights reserved.

  4. Transseptal Leftventricular Endocardial Pacing is an Alternative Technique in Cardiac Resynchronization Therapy. One Year Experience in a High Volume Center.

    PubMed

    Neuhoff, I; Szilágyi, S; Molnár, L; Osztheimer, I; Zima, E; Dan, G A; Merkely, B; Gellér, L

    2016-01-01

    In patients receiving cardiac resynchronization therapy (CRT), failure rate to implant the left ventricular (LV) lead by the traditional trans-venous approach is 4-8%. Surgical epicardial implantation is considered as an alternative, but this technique is not without morbidity. Evidence from case documentation and from small trial batches demonstrated the viability of endocardial LV lead implantation where surgical epicardial lead placement is not applicable. Four patients were implanted with endocardial LV lead using the transseptal atrial approach after unsuccessful transvenous implantation. Implantation of an endocardial active fixation LV leads was successful in all patients with stable electrical parameters immediately after implantation and over the follow-up period. All patients received anticoagulation therapy in order to target the international normalized ratio of 2.5-3.5 and have not experienced any thromboembolic, hemorrhagic events, or infection. Follow-up echocardiography indicated significant improvement of LV systolic function (24 + 4.9 to 32 + 5.1 %, P = 0.023) with a notable improvement of the functional status. Endocardial left ventricular lead implantation can be a valuable and safe alternative technique to enable LV stimulation in high surgical risk patients where standard coronary sinus implant is unsuccessful.

  5. A Hybrid Method for Endocardial Contour Extraction of Right Ventricle in 4-Slices from 3D Echocardiography Dataset.

    PubMed

    Dawood, Faten A; Rahmat, Rahmita W; Kadiman, Suhaini B; Abdullah, Lili N; Zamrin, Mohd D

    2014-01-01

    This paper presents a hybrid method to extract endocardial contour of the right ventricular (RV) in 4-slices from 3D echocardiography dataset. The overall framework comprises four processing phases. In Phase I, the region of interest (ROI) is identified by estimating the cavity boundary. Speckle noise reduction and contrast enhancement were implemented in Phase II as preprocessing tasks. In Phase III, the RV cavity region was segmented by generating intensity threshold which was used for once for all frames. Finally, Phase IV is proposed to extract the RV endocardial contour in a complete cardiac cycle using a combination of shape-based contour detection and improved radial search algorithm. The proposed method was applied to 16 datasets of 3D echocardiography encompassing the RV in long-axis view. The accuracy of experimental results obtained by the proposed method was evaluated qualitatively and quantitatively. It has been done by comparing the segmentation results of RV cavity based on endocardial contour extraction with the ground truth. The comparative analysis results show that the proposed method performs efficiently in all datasets with overall performance of 95% and the root mean square distances (RMSD) measure in terms of mean ± SD was found to be 2.21 ± 0.35 mm for RV endocardial contours.

  6. Electrical storm originating from a left ventricular epicardial scar in a patient with completely normal endocardial voltage.

    PubMed

    Sternick, Eduardo Back; Piorkowski, Christopher; Hindricks, Gerhard; Dagres, Nikolaos; Sommer, Philipp

    2011-11-01

    We report a patient with non-ischemic dilated cardiomyopathy presenting with an electrical storm because of a poorly tolerated monomorphic ventricular tachycardia. Electroanatomical mapping revealed a scar restricted to the epicardium, whereas the endocardial voltage map was completely normal. Epicardial catheter ablation based on substrate mapping and limited pace and entrainment mapping eliminated the tachycardia.

  7. Early morphologic changes following microwave endocardial ablation for treatment of chronic atrial fibrillation during mitral valve surgery.

    PubMed

    Climent, Vicente; Hurlé, Aquilino; Ho, Siew Yen; Sáenz-Santamaría, Javier; Nogales, Agustín G; Sánchez-Quintana, Damián

    2004-11-01

    The aim of this study was to investigate the early qualitative and quantitative structural changes in the left atrial wall after endocardial microwave ablation in patients with chronic atrial fibrillation (AF) undergoing mitral surgery. Seven patients with chronic AF of for at least 6 months underwent surgical microwave energy ablation. Linear isolation of pulmonary veins was performed in all patients by microwave energy applications to the endocardial surface delivered by catheter at 65-W constant power for 45 seconds. Biopsies were obtained from a selected site (below the right lower pulmonary vein) of the left atrial posterior wall before and after the ablation procedure in all patients. Control tissues from the same sites were obtained at autopsy from patients with noncardiac causes of death. Light and electron microscopy was used to examine qualitative and quantitative changes in tissue morphology. Tissues after endocardial ablation procedure showed significantly increased loss of contractile material. Electron microscopy of atrial tissue demonstrated loss of profile of perinuclear and plasma membranes of myocytes, disruption of the endothelial cells of capillary vessels, and presence of macrophages. Lesions created by endocardial microwave energy ablation revealed a transmural effect on the left atrial wall without a significant reduction in thickness but a significant increase in the myolytic areas involving the entire cytosol and occlusion of the small intramyocardial vessels within the ablative lesion.

  8. The circumferential thigh lift and vertical extension circumferential thigh lift: maximizing aesthetics and safety in lower extremity contouring.

    PubMed

    Kolker, Adam R; Xipoleas, George D

    2011-05-01

    Excess skin and soft tissue of the thighs after massive weight loss (MWL) can present with varying degrees of severity. The classic medial thigh lift has considerable limitations in the postbariatric population, inspiring the quest for safer and more effective technical solutions. In this study, the circumferential thigh lift (CTL), and CTL with vertical extension, predicated on a theoretical and technical approach that improves safety and aesthetics in thighplasty after MWL, is described and evaluated. Nine patients were treated; all patients experienced MWL and all had previously undergone first-stage contouring with circumferential abdominal dermolipectomy. Patients were treated with a prone-to-supine approach with concomitant suction-assisted lipectomy (SAL). Lumbar and lateral thigh and infragluteal skin and fat were excised to the midaxillary lines and medial thigh meridians. Direct excision of anterolateral thigh skin was carried in a superficial plane into the medial thigh to confluence with the posterior excision. No direct undermining of any skin margin was performed. When soft-tissue excess is limited to the proximal third of the thigh, a horizontal excision pattern is used; with middle and lower one-third thigh excess, a vertical extension is employed. The medial superficial fascial system is anchored to the superficial perineal fascia. Data were reviewed retrospectively. In the 9 procedures performed, 3 achieved MWL by nonsurgical means, and 6 underwent bariatric surgery (bypass or band). Three patients were treated with CTL, and 6 with CTL with vertical extension. There were 3 seromas (33%) treated with percutaneous aspiration. There was 1 case of cellulitis (11%) treated successfully with in-office incision and drainage, and oral antibiotics. There were no hematomas, skin loss, wound dehiscences, lymphedema, or vulvar distortions. The circumferential excision of thigh excess without direct undermining allows for the maintenance of a rich blood supply

  9. Noninvasive epicardial and endocardial electrocardiographic imaging of scar-related ventricular tachycardia.

    PubMed

    Wang, Linwei; Gharbia, Omar A; Horáček, B Milan; Sapp, John L

    The majority of life-threatening ventricular tachycardias (VTs) are sustained by heterogeneous scar substrates with narrow strands of surviving tissue. An effective treatment for scar-related VT is to modify the underlying scar substrate by catheter ablation. If activation sequence and entrainment mapping can be performed during sustained VT, the exit and isthmus of the circuit can often be identified. However, with invasive catheter mapping, only monomorphic VT that is hemodynamically stable can be mapped in this manner. For the majority of patients with poorly tolerated VTs or multiple VTs, a close inspection of the re-entry circuit is not possible. A noninvasive approach to fast mapping of unstable VTs can potentially allow an improved identification of critical ablation sites. For patients who underwent catheter ablation of scar-related VT, CT scan was obtained prior to the ablation procedure and 120-lead body-surface electrocardiograms (ECGs) were acquired during induced VTs. These data were used for noninvasive ECG imaging to computationally reconstruct electrical potentials on the epicardium and on the endocardium of both ventricles. Activation time and phase maps of the VT circuit were extracted from the reconstructed electrograms. They were analyzed with respect to scar substrate obtained from catheter mapping, as well as VT exits confirmed through ablation sites that successfully terminated the VT. The reconstructed re-entry circuits correctly revealed both epicardial and endocardial origins of activation, consistent with locations of exit sites confirmed from the ablation procedure. The temporal dynamics of the re-entry circuits, particularly the slowing of conduction as indicated by the crowding and zig-zag conducting of the activation isochrones, collocated well with scar substrate obtained by catheter voltage maps. Furthermore, the results indicated that some re-entry circuits involve both the epicardial and endocardial layers, and can only be

  10. Cardiac Resynchronization Therapy With Wireless Left Ventricular Endocardial Pacing: The SELECT-LV Study.

    PubMed

    Reddy, Vivek Y; Miller, Marc A; Neuzil, Petr; Søgaard, Peter; Butter, Christian; Seifert, Martin; Delnoy, Peter Paul; van Erven, Lieselot; Schalji, Martin; Boersma, Lucas V A; Riahi, Sam

    2017-05-02

    A total of 30% to 40% of patients with congestive heart failure eligible for cardiac resynchronization therapy (CRT) either do not respond to conventional CRT or remain untreated due to an inability or impediment to coronary sinus (CS) lead implantation. The WiSE-CRT system (EBR Systems, Sunnyvale, California) was developed to address this at-risk patient population by performing biventricular pacing via a wireless left ventricular (LV) endocardial pacing electrode. The SELECT-LV (Safety and Performance of Electrodes implanted in the Left Ventricle) study is a prospective multicenter non-randomized trial assessing the safety and performance of the WiSE-CRT system. A total of 35 patients indicated for CRT who had "failed" conventional CRT underwent implantation of an LV endocardial pacing electrode and a subcutaneous pulse generator. System performance, clinical efficacy, and safety events were assessed out to 6 months post-implant. The procedure was successful in 97.1% (n = 34) of attempted implants. The most common indications for endocardial LV pacing were difficult CS anatomy (n =12), failure to respond to conventional CRT (n = 10), and a high CS pacing threshold or phrenic nerve capture (n = 5). The primary performance endpoint, biventricular pacing on the 12-lead electrocardiogram at 1 month, was achieved in 33 of 34 patients. A total of 28 patients (84.8%) had improvement in the clinical composite score at 6 months, and 21 (66%) demonstrated a positive echocardiographic CRT response (≥5% absolute increase in LV ejection fraction). There were no pericardial effusions, but serious procedure/device-related events occurred in 3 patients (8.6%) within 24 h, and 8 patients (22.9%) between 24 h and 1 month. The SELECT-LV study demonstrates the clinical feasibility for the WiSE-CRT system, and provided clinical benefits to a majority of patients within an otherwise "failed" CRT population. (Safety and Performance of Electrodes Implanted in the Left Ventricle

  11. The neuropeptide galanin promotes an anti-thrombotic phenotype on endocardial endothelial cells from heart failure patients.

    PubMed

    Tyrrell, Christina; Toyooka, Amanda; Khan, Faiza; Thornburg, Kent L; Mudd, James O; Hasan, Wohaib

    2017-09-01

    Thromboembolic complications are a significant cause of mortality and re-hospitalization in heart failure (HF) patients. One source of thrombi is the ventricular endocardial surface that becomes increasingly pro-thrombotic as HF progresses. Anticoagulation comes with bleeding risks so identifying therapeutic agents for improving cardiac endothelial health are of critical clinical importance. Endocardial endothelial cells are closely apposed to cardiac sympathetic nerves. In HF, cardiac sympathetic nerves are dysregulated and promote disease progression. Whether endocardial endothelial health and function is impacted by sympathetic dysregulation in HF is unknown. Also unexplored is the impact of neuropeptides, such as galanin and neuropeptide Y (NPY), co-released from sympathetic nerve terminals, on endothelial health. In this study we examined the effect of sympathetic nerve-released neurotransmitters and neuropeptides on the procoagulant phenotype of cultured human endocardial endothelial cells from HF patients. As a functional readout of procoagulant state we examined thrombin-mediated von Willebrand factor (vWF) extrusion and multimer expression. We demonstrate that vWF extrusion and multimer expression is promoted by thrombin, that isoproterenol (a beta-adrenergic receptor agonist) augments this effect, whereas co-treatment with the beta-blockers propranolol and carvedilol blocks this effect. We also show that vWF extrusion and multimer expression is attenuated by treatment with the neuropeptide galanin, but not with NPY. Our results are consistent with a protective role of beta-blockers and galanin on endocardial endothelial health in heart failure. Improving endothelial health through galanin therapy is a future clinical application of this study. Copyright © 2017. Published by Elsevier B.V.

  12. Congenital endocardial cushion defect detected during uncomplicated pregnancy: a case report.

    PubMed

    Frank, Jennifer; Beck, David

    2012-01-01

    The first symptoms of previously undiagnosed congenital heart disease may become apparent during pregnancy. It is important to recognize structural heart lesions since they require additional monitoring during the prenatal, peripartum, and postpartum periods and are associated with increased maternal and fetal morbidity and mortality. We report a case of a new diagnosis of an endocardial cushion defect in an otherwise healthy woman in her third trimester whose presenting complaint was dyspnea in the left lateral decubitus position. We located only one other case report of a congenital heart lesion first diagnosed during pregnancy. While rare, since the signs and symptoms of congenital heart disease may also occur in normal pregnant women, it is important for the clinician to be aware that structural heart lesions are part of the differential diagnosis.

  13. Automatic generation of endocardial surface meshes with 1-to-1 correspondence from cine-MR images

    NASA Astrophysics Data System (ADS)

    Su, Yi; Teo, S.-K.; Lim, C. W.; Zhong, L.; Tan, R. S.

    2015-03-01

    In this work, we develop an automatic method to generate a set of 4D 1-to-1 corresponding surface meshes of the left ventricle (LV) endocardial surface which are motion registered over the whole cardiac cycle. These 4D meshes have 1- to-1 point correspondence over the entire set, and is suitable for advanced computational processing, such as shape analysis, motion analysis and finite element modelling. The inputs to the method are the set of 3D LV endocardial surface meshes of the different frames/phases of the cardiac cycle. Each of these meshes is reconstructed independently from border-delineated MR images and they have no correspondence in terms of number of vertices/points and mesh connectivity. To generate point correspondence, the first frame of the LV mesh model is used as a template to be matched to the shape of the meshes in the subsequent phases. There are two stages in the mesh correspondence process: (1) a coarse matching phase, and (2) a fine matching phase. In the coarse matching phase, an initial rough matching between the template and the target is achieved using a radial basis function (RBF) morphing process. The feature points on the template and target meshes are automatically identified using a 16-segment nomenclature of the LV. In the fine matching phase, a progressive mesh projection process is used to conform the rough estimate to fit the exact shape of the target. In addition, an optimization-based smoothing process is used to achieve superior mesh quality and continuous point motion.

  14. Increased Hemodynamic Load in Early Embryonic Stages Alters Endocardial to Mesenchymal Transition

    PubMed Central

    Midgett, Madeline; López, Claudia S.; David, Larry; Maloyan, Alina; Rugonyi, Sandra

    2017-01-01

    Normal blood flow is essential for proper heart formation during embryonic development, as abnormal hemodynamic load (blood pressure and shear stress) results in cardiac defects seen in congenital heart disease. However, the progressive detrimental remodeling processes that relate altered blood flow to cardiac defects remain unclear. Endothelial–mesenchymal cell transition is one of the many complex developmental events involved in transforming the early embryonic outflow tract into the aorta, pulmonary trunk, interventricular septum, and semilunar valves. This study elucidated the effects of increased hemodynamic load on endothelial–mesenchymal transition remodeling of the outflow tract cushions in vivo. Outflow tract banding was used to increase hemodynamic load in the chicken embryo heart between Hamburger and Hamilton stages 18 and 24. Increased hemodynamic load induced increased cell density in outflow tract cushions, fewer cells along the endocardial lining, endocardium junction disruption, and altered periostin expression as measured by confocal microscopy analysis. In addition, 3D focused ion beam scanning electron microscopy analysis determined that a portion of endocardial cells adopted a migratory shape after outflow tract banding that is more irregular, elongated, and with extensive cellular projections compared to normal cells. Proteomic mass-spectrometry analysis quantified altered protein composition after banding that is consistent with a more active stage of endothelial–mesenchymal transition. Outflow tract banding enhances the endothelial–mesenchymal transition phenotype during formation of the outflow tract cushions, suggesting that endothelial–mesenchymal transition is a critical developmental process that when disturbed by altered blood flow gives rise to cardiac malformation and defects. PMID:28228731

  15. Endocardial left ventricle feature tracking and reconstruction from tri-plane trans-esophageal echocardiography data

    NASA Astrophysics Data System (ADS)

    Dangi, Shusil; Ben-Zikri, Yehuda K.; Cahill, Nathan; Schwarz, Karl Q.; Linte, Cristian A.

    2015-03-01

    Two-dimensional (2D) ultrasound (US) has been the clinical standard for over two decades for monitoring and assessing cardiac function and providing support via intra-operative visualization and guidance for minimally invasive cardiac interventions. Developments in three-dimensional (3D) image acquisition and transducer design and technology have revolutionized echocardiography imaging enabling both real-time 3D trans-esophageal and intra-cardiac image acquisition. However, in most cases the clinicians do not access the entire 3D image volume when analyzing the data, rather they focus on several key views that render the cardiac anatomy of interest during the US imaging exam. This approach enables image acquisition at a much higher spatial and temporal resolution. Two such common approaches are the bi-plane and tri-plane data acquisition protocols; as their name states, the former comprises two orthogonal image views, while the latter depicts the cardiac anatomy based on three co-axially intersecting views spaced at 600 to one another. Since cardiac anatomy is continuously changing, the intra-operative anatomy depicted using real-time US imaging also needs to be updated by tracking the key features of interest and endocardial left ventricle (LV) boundaries. Therefore, rapid automatic feature tracking in US images is critical for three reasons: 1) to perform cardiac function assessment; 2) to identify location of surgical targets for accurate tool to target navigation and on-target instrument positioning; and 3) to enable pre- to intra-op image registration as a means to fuse pre-op CT or MR images used during planning with intra-operative images for enhanced guidance. In this paper we utilize monogenic filtering, graph-cut based segmentation and robust spline smoothing in a combined work flow to process the acquired tri-plane TEE time series US images and demonstrate robust and accurate tracking of the LV endocardial features. We reconstruct the endocardial LV

  16. Downscaling of inundation extents

    NASA Astrophysics Data System (ADS)

    Aires, Filipe; Prigent, Catherine; Papa, Fabrice

    2014-05-01

    The Global Inundation Extent from Multi-Satellite (GIEMS) provides multi-year monthly variations of the global surface water extent at about 25 kmx25 km resolution, from 1993 to 2007. It is derived from multiple satellite observations. Its spatial resolution is usually compatible with climate model outputs and with global land surface model grids but is clearly not adequate for local applications that require the characterization of small individual water bodies. There is today a strong demand for high-resolution inundation extent datasets, for a large variety of applications such as water management, regional hydrological modeling, or for the analysis of mosquitos-related diseases. This paper present three approaches to do downscale GIEMS: The first one is based on a image-processing technique using neighborhood constraints. The third approach uses a PCA representation to perform an algebraic inversion. The PCA-representation is also very convenient to perform temporal and spatial interpolation of complexe inundation fields. The third downscaling method uses topography information from Hydroshed Digital Elevation Model (DEM). Information such as the elevation, distance to river and flow accumulation are used to define a ``flood ability index'' that is used by the downscaling. Three basins will be considered for illustrative purposes: Amazon, Niger and Mekong. Aires, F., F. Papa, C. Prigent, J.-F. Cretaux and M. Berge-Nguyen, Characterization and downscaling of the inundation extent over the Inner Niger delta using a multi-wavelength retrievals and Modis data, J. of Hydrometeorology, in press, 2014. Aires, F., F. Papa and C. Prigent, A long-term, high-resolution wetland dataset over the Amazon basin, downscaled from a multi-wavelength retrieval using SAR, J. of Hydrometeorology, 14, 594-6007, 2013. Prigent, C., F. Papa, F. Aires, C. Jimenez, W.B. Rossow, and E. Matthews. Changes in land surface water dynamics since the 1990s and relation to population pressure

  17. Fracture behavior of short circumferentially surface-cracked pipe

    SciTech Connect

    Krishnaswamy, P.; Scott, P.; Mohan, R.

    1995-11-01

    This topical report summarizes the work performed for the Nuclear Regulatory Comniission`s (NRC) research program entitled ``Short Cracks in Piping and Piping Welds`` that specifically focuses on pipes with short, circumferential surface cracks. The following details are provided in this report: (i) material property deteminations, (ii) pipe fracture experiments, (iii) development, modification and validation of fracture analysis methods, and (iv) impact of this work on the ASME Section XI Flaw Evaluation Procedures. The material properties developed and used in the analysis of the experiments are included in this report and have been implemented into the NRC`s PIFRAC database. Six full-scale pipe experiments were conducted during this program. The analyses methods reported here fall into three categories (i) limit-load approaches, (ii) design criteria, and (iii) elastic-plastic fracture methods. These methods were evaluated by comparing the analytical predictions with experimental data. The results, using 44 pipe experiments from this and other programs, showed that the SC.TNP1 and DPZP analyses were the most accurate in predicting maximum load. New Z-factors were developed using these methods. These are being considered for updating the ASME Section XI criteria.

  18. Circumferential wires as a supplement to intramedullary nailing in unstable trochanteric hip fractures

    PubMed Central

    2012-01-01

    Background and purpose Fixation of unstable trochanteric fractures is challenging. Application of a circumferential wire may facilitate bone contact and avoid postoperative fracture displacement. However, the use of circumferential wires remains controversial due to possible disturbance of the blood supply to the underlying bone. We evaluated the results of applied circumferential wires, concentrating mainly on complications and reoperations. Patients and methods 60 patients with unstable trochanteric fractures and use of circumferential wires (1 or more) and an intramedullary nail were included from 2 centers. We retrospectively assessed complications and reoperation rates within the first postoperative year. Results In 37 of the 60 patients, 2 or more circumferential wires were used. Anatomic reduction was achieved in 24 of the patients and a total cortical displacement of ≤ 10 mm was achieved in 26 other patients. 6 of the 43 patients with radiographic audit after 12 weeks sustained a subsequent fracture displacement of more than 5 mm. 4 patients underwent reoperation: 1 due to deep infection, 1 due to technical failure during osteosynthesis, 1 had a screw cut out, and 1 sustained a new fracture following a new fall. Interpretation Application of circumferential wires as a supplement to intramedullary nails in unstable trochanteric fractures is an option as it provides good primary reduction which, in most patients, is maintained over time—with no apparent increase in reoperation rate. Based on our results and on other reports, the use of circumferential wires does not appear to be harmful as sometimes claimed. PMID:22329672

  19. Nonlinear giant magnetoimpedance and the asymmetric circumferential magnetization process in soft magnetic wires

    NASA Astrophysics Data System (ADS)

    Gómez-Polo, C.; Duque, J. G. S.; Knobel, M.

    2004-07-01

    The magnetoimpedance effect and its nonlinear terms are analysed for a (Co0.94Fe0.06)72.5Si12.5B15 amorphous wire. In order to enhance the nonlinear contribution the sample was previously subjected to current annealing (Joule heating) to induce a circumferential anisotropy. The effect of the application of a torsional strain on the nonlinear magnetoimpedance is analysed in terms of the torsional dependence of the magnetic permeability, evaluated through experimental circumferential hysteresis loops. The results obtained clearly confirm the direct correlation between the asymmetric circumferential magnetization process and the occurrence of nonlinear second-harmonic terms in the magnetoimpedance voltage.

  20. Design of optical cloaks and illusion devices along a circumferential direction in curvilinear coordinates

    NASA Astrophysics Data System (ADS)

    Chen, Tungyang; Yu, Shang-Ru

    2010-11-01

    We propose a cloaking and illusion device of circumferential topology based on the concept of transformation optics. The device is capable to cloak an object and/or simultaneously generate illusion images along a circumferential direction in curvilinear orthogonal coordinates. This feature allows us to construct multiple illusions in different ways, irrespective of the profile and direction of incident wave. Particularly when the device is served as a building brick of a larger device, one can generate a circumferential array of illusions in a periodic or any preferred pattern. We demonstrate the effectiveness of the proposed illusion devices by carrying out full wave simulations based on finite element calculations.

  1. Circumferential cracking in steam generator tubes repaired by mechanical sleeving

    SciTech Connect

    Stubbe, J.; Pierson, E.; Laire, C.; Nedden, L. zur; Somville, P.; Royen, P. Van

    1995-12-31

    After one service cycle, leaks were detected in Doel 4 steam generator (SG) tubes repaired by mechanical sleeving (hydraulically + roll expanded). Two tubes were pulled and examined, one of them showing a big leak and the second being, pulled randomly. They both revealed through wall circumferential primary water stress corrosion cracking (PWSCC) at the upper hydraulic transition so that it was concluded that the problem was generic. A thorough assessment of the root causes of failure was undertaken, including stress and strain direct measurement by X-ray diffraction and photoelasticity, local stresses and temperature evaluation by calculation and stress corrosion cracking tests. Stress corrosion tests were carried out in 10 % NAOH environment, on mock-ups manufactured from reserve tubing of the plant simulating not only the upper joint but also the complete assembly (two joints). An estimate of the expected life was performed by comparison with reference mock-ups representative of the roll transitions (including the kiss roll). The findings are that the hydraulic expansion may generate high residual stresses, in spite of the very low residual deformations. Concerning, the temperature however, there are some indications that it could be substantially lower at the level of the cracking than at the tube to tubesheet roll transitions, which makes the quantified evaluation somewhat inaccurate. It is concluded that repair by mechanical sleeving is influenced by many parameters, including details of the installation procedure. Lifetime may be very limited when applied to PWSCC sensitive tubes and must be evaluated by appropriate testing. In particular, corrosion mock-ups should represent the entire sleeve, with both joints.

  2. An evaluation of epidural analgesia following circumferential belt lipectomy.

    PubMed

    Michaud, André-Paul; Rosenquist, Richard W; Cram, Albert E; Aly, Al S

    2007-08-01

    Belt lipectomy combines traditional abdominoplasty with a circumferential excision of skin and fat, with resultant buttock and lateral thigh lifts. Because of the extensive nature of the procedure, postoperative pain management can be difficult. Epidural analgesia has been shown to be efficacious in treating postoperative pain. This study compares the postoperative use of epidural analgesia with more traditional pain management regimens in a large series of belt lipectomy patients. Charts of 62 belt lipectomy patients were examined retrospectively. Postoperative pain control regimen, pain scores, total amount of opioids administered, and side effects encountered were recorded. Twenty-seven patients had traditional pain control regimens, opioids on demand, and pain control pumps. Thirty-five patients received epidural analgesia as their primary mode of postoperative pain control. Pain scores and total nonepidural opioids used were lower in the epidural analgesia group on postoperative days 0 and 1 compared with the nonepidural group. The two groups converged on postoperative days 2 through 5, sharing similar pain scores and opioid use after discontinuation of epidural analgesia. The incidence of side effects was similar in the two groups, with the exception of pruritus, which was much more prominent in the epidural group. Eight of the 35 epidural patients (23 percent) experienced transient and minor complications associated with epidural therapy; several resolved spontaneously, whereas the balance resolved with cessation or modification of the epidural infusion. Epidural analgesia is more effective than traditional pain control methods in reducing immediate postoperative pain in belt lipectomy patients. On the basis of these findings, epidural analgesia should also be considered for postoperative pain management in other truncal procedures.

  3. Vagal tone augmentation to the atrioventricular node in humans: efficacy and safety of burst endocardial stimulation.

    PubMed

    Rossi, Pietro; Bianchi, Stefano; Monari, Giancarlo; Della Scala, Alberto; Porcelli, Daniele; Valsecchi, Sergio; Canonaco, Sergio; Kornet, Lilian; Azzolini, Paolo

    2010-05-01

    Control of atrioventricular (AV) nodal conduction by endocardial stimulation of efferent AV nodal vagal fibers [atrioventricular nodal vagal stimulation (AVNS)] is a promising approach for long-term device-based modulation of ventricular rate during atrial fibrillation (AF). However, few data on the efficacy of AVNS delivered as high-frequency stimulus packages (burst AVNS) in humans are available. The purpose of this study was to determine whether burst AVNS can to modulate AV nodal conduction during AF and whether burst AVNS delivered during sinus rhythm (SR) in the effective atrial refractory period allows safe implantation of a permanent lead in a position suitable for AVNS. Twenty patients (10 in SR and 10 in AF) who were candidates for dual-chamber pacemaker implantation for sick sinus syndrome were enrolled in the study. The posteroseptal right atrium was mapped to identify a location at which burst AVNS would achieve AV nodal conduction modulation (lengthening of PR interval in SR and reduction of ventricular rate in AF). Subsequently, a lead was screwed in at that site and burst stimulation (pulse rate 50 Hz, burst duration 180 ms) was delivered at different burst rates, pulse durations, and amplitudes. In all SR patients, PR-interval prolongation was evoked at 90 and 120 bursts/minute with pulse durations < or =1 ms. Specifically, the mean voltages required to obtain PR-interval prolongation and advanced AV block were 4.3 +/- 2.2 V and 5.4 +/- 1.8 V (at 90 bursts/minute and 1 ms), respectively. Similarly, ventricular rate reduction was obtained in all AF patients, starting from 90 bursts/minute and 0.5-ms pulse duration (at 5.4 +/- 1.8 V). Ventricular arrhythmias were never induced during AVNS. Endocardial right atrial burst AVNS reduces ventricular rate during AF. Burst AVNS delivered during SR in the effective atrial refractory period allows optimization of lead positioning for AVNS. Copyright 2010 Heart Rhythm Society. Published by Elsevier Inc. All

  4. A circumferential non-uniform effect model for multistage axial-flow compressor throughflow

    NASA Astrophysics Data System (ADS)

    Li, Shiming; Chen, Maozhang

    1992-04-01

    The effects of momentum and energy transportation caused by circumferential nonuniformities of the flow in a multistage axial compressor are studied. A model has been developed to represent the circumferential nonuniform stresses and heat flux. A preliminary comparison between experimental results and the model demonstrates that this model is feasible. The momentum transport effects of circumferential nonuniformities are not distinct, but the energy transport effects of the nonuniformities are quite strong and have the same order of magnitude as the turbulent diffusion. The relative importances of the turbulent diffusion and the nonuniformities depend on compressor configuration, loadings, and spanwise positions in the compressor. Compared with the effects of their mean stream counterparts, the circumferential nonuniform stresses can be sometimes neglected, according to the compressor loadings, configuration, and the calculation tolerances.

  5. Qualitative and quantitative effects of harmonic echocardiographic imaging on endocardial edge definition and side-lobe artifacts

    NASA Technical Reports Server (NTRS)

    Rubin, D. N.; Yazbek, N.; Garcia, M. J.; Stewart, W. J.; Thomas, J. D.

    2000-01-01

    Harmonic imaging is a new ultrasonographic technique that is designed to improve image quality by exploiting the spontaneous generation of higher frequencies as ultrasound propagates through tissue. We studied 51 difficult-to-image patients with blinded side-by-side cineloop evaluation of endocardial border definition by harmonic versus fundamental imaging. In addition, quantitative intensities from cavity versus wall were compared for harmonic versus fundamental imaging. Harmonic imaging improved left ventricular endocardial border delineation over fundamental imaging (superior: harmonic = 71.1%, fundamental = 18.7%; similar: 10.2%; P <.001). Quantitative analysis of 100 wall/cavity combinations demonstrated brighter wall segments and more strikingly darker cavities during harmonic imaging (cavity intensity on a 0 to 255 scale: fundamental = 15.6 +/- 8.6; harmonic = 6.0 +/- 5.3; P <.0001), which led to enhanced contrast between the wall and cavity (1.89 versus 1.19, P <.0001). Harmonic imaging reduces side-lobe artifacts, resulting in a darker cavity and brighter walls, thereby improving image contrast and endocardial delineation.

  6. Usefulness of ventricular endocardial electric reconstruction from body surface potential maps to noninvasively localize ventricular ectopic activity in patients.

    PubMed

    Lai, Dakun; Sun, Jian; Li, Yigang; He, Bin

    2013-06-07

    As radio frequency (RF) catheter ablation becomes increasingly prevalent in the management of ventricular arrhythmia in patients, an accurate and rapid determination of the arrhythmogenic site is of important clinical interest. The aim of this study was to test the hypothesis that the inversely reconstructed ventricular endocardial current density distribution from body surface potential maps (BSPMs) can localize the regions critical for maintenance of a ventricular ectopic activity. Patients with isolated and monomorphic premature ventricular contractions (PVCs) were investigated by noninvasive BSPMs and subsequent invasive catheter mapping and ablation. Equivalent current density (CD) reconstruction (CDR) during symptomatic PVCs was obtained on the endocardial ventricular surface in six patients (four men, two women, years 23-77), and the origin of the spontaneous ectopic activity was localized at the location of the maximum CD value. Compared with the last (successful) ablation site (LAS), the mean and standard deviation of localization error of the CDR approach were 13.8 and 1.3 mm, respectively. In comparison, the distance between the LASs and the estimated locations of an equivalent single moving dipole in the heart was 25.5 ± 5.5 mm. The obtained CD distribution of activated sources extending from the catheter ablation site also showed a high consistency with the invasively recorded electroanatomical maps. The noninvasively reconstructed endocardial CD distribution is suitable to predict a region of interest containing or close to arrhythmia source, which may have the potential to guide RF catheter ablation.

  7. Peak endocardial acceleration-based clinical testing of the "BEST" DDDR pacemaker. European PEA Clinical Investigation Group.

    PubMed

    Langenfeld, H; Krein, A; Kirstein, M; Binner, L

    1998-11-01

    The peak endocardial acceleration (PEA, unit g) shows a near correlation with myocardial contractility during the isometric systolic contraction of the heart (dP/dtmax), with sympathetic activity and, thus, with physiological heart rate modulation. The (Biomechanical Endocardial Sorin Transducer (BEST) sensor is incorporated in the tip of a pacing lead and measures PEA directly near the myocardium. In an international study, the lead was implanted with the dual chamber pacemaker Living-1 (Sorin) in 105 patients. The behavior of the PEA signal was tested under conditions of physical and mental stress and during daily life activities by 24-hour recordings of PEA (PEA Holter) at 1 to 2 months and approximately 1 year after implantation. Implantation of the BEST lead was performed without complications in all patients. The sensor functioned properly in the short- and long-term in 98% of patients. Although PEA values differed from patient to patient, the values closely reflected the variations in sympathetic activity due to physical and mental stress in each patient. During exercise and during daily life activities a close correlation between PEA and heart rate was observed among patients with normal sinus rhythm. Peak endocardial acceleration allows a nearly physiological control of the pacing rate.

  8. Direct left ventricular endocardial pacing: an alternative when traditional resynchronization via coronary sinus is not feasible or effective.

    PubMed

    Moriña-Vázquez, Pablo; Roa-Garrido, Jessica; Fernández-Gómez, Juan M; Venegas-Gamero, José; Pichardo, Rafael B; Carranza, Manuel H

    2013-06-01

    Biventricular pacing through the coronary sinus (CS) is effective for the treatment of patients with heart failure and left bundle-branch block. However, this approach is not always feasible. Although surgical epicardial lead implantation is an alternative, the technique may be deleterious in some patients. Thus, direct left ventricular (LV) endocardial pacing under local anesthesia may be an option. We describe our technique and analyze the results of direct LV endocardial pacing. Fourteen patients with failed resynchronization via CS (April 2006-September 2011) were selected. Using a femoral approach, we performed transseptal puncture and LV mapping, then fixed the active lead where the longest electrical delay was observed; the generator was placed in the anterior thigh. For resynchronization, eight patients with a device previously implanted through the upper veins received a single-chamber generator that was set to the VVT mode to sense the subclavian pacing spike. Six patients received a complete femoral resynchronization system with either a defibrillator or pacemaker. Patients were followed for 6-54 months. The LV lead was successfully implanted in all cases. Two patients experienced excessive bleeding and two died during follow-up. All except one improved at least one New York Heart Association class and experienced improved left ventricle ejection fraction. One patient with recurrent episodes of ventricular fibrillation was asymptomatic. Direct LV endocardial pacing is safe and may be a less risky, more efficient alternative than surgical epicardial lead implantation for resynchronization via CS. ©2013, The Authors. Journal compilation ©2013 Wiley Periodicals, Inc.

  9. Deletion of Fstl1 (Follistatin-Like 1) From the Endocardial/Endothelial Lineage Causes Mitral Valve Disease.

    PubMed

    Prakash, Stuti; Borreguero, Luis J J; Sylva, Marc; Flores Ruiz, Lorena; Rezai, Fereshte; Gunst, Quinn D; de la Pompa, José-Luis; Ruijter, Jan M; van den Hoff, Maurice J B

    2017-09-01

    Fstl1 (Follistatin-like 1) is a secreted protein that is expressed in the atrioventricular valves throughout embryonic development, postnatal maturation, and adulthood. In this study, we investigated the loss of Fstl1 in the endocardium/endothelium and their derived cells. We conditionally ablated Fstl1 from the endocardial lineage using a transgenic Tie2-Cre mouse model. These mice showed a sustained Bmp and Tgfβ signaling after birth. This resulted in ongoing proliferation and endocardial-to-mesenchymal transition and ultimately in deformed nonfunctional mitral valves and a hypertrophic dilated heart. Echocardiographic and electrocardiographic analyses revealed that loss of Fstl1 leads to mitral regurgitation and left ventricular diastolic dysfunction. Cardiac function gradually deteriorated resulting in heart failure with preserved ejection fraction and death of the mice between 2 and 4 weeks after birth. We report on a mouse model in which deletion of Fstl1 from the endocardial/endothelial lineage results in deformed mitral valves, which cause regurgitation, heart failure, and early cardiac death. The findings provide a potential molecular target for the clinical research into myxomatous mitral valve disease. © 2017 American Heart Association, Inc.

  10. Automated classification of wall motion abnormalities by principal component analysis of endocardial shape motion patterns in echocardiograms

    NASA Astrophysics Data System (ADS)

    Bosch, Johan G.; Nijland, Francisca; Mitchell, Steven C.; Lelieveldt, Boudewijn P. F.; Kamp, Otto; Sonka, Milan; Reiber, Johan H. C.

    2003-05-01

    Principal Component Analysis of sets of temporal shape sequences renders eigenvariations of shape/motion, including typical normal and pathological endocardial contraction patterns. A previously developed Active Appearance Model for time sequences (AAMM) was employed to derive AAMM shape coefficients (ASCs) and we hypothesized these would allow classification of wall motion abnormalities (WMA). A set of stress echocardiograms (single-beat 4-chamber and 2-chamber sequences with expert-verified endocardial contours) of 129 infarct patients was split randomly into training (n=65) and testing (n=64) sets. AAMMs were generated from the training set and for all sequences ASCs were extracted and statistically related to regional/global Visual Wall Motion Scoring (VWMS) and clinical infarct severity and volumetric parameters. Linear regression showed clear correlations between ASCs and VWMS. Infarct severity measures correlated poorly to both ASCs and VWMS. Discriminant analysis showed good prediction from low #ASCs of both segmental (85% correctness) and global WMA (90% correctness). Volumetric parameters correlated poorly to regional VWMS. Conclusions: 1)ASCs show promising accuracy for automated WMA classification. 2)VWMS and endocardial border motion are closely related; with accurate automated border detection, automated WMA classification should be feasible. 3)ASC shape analysis allows contour set evaluation by direct comparison to clinical parameters.

  11. Qualitative and quantitative effects of harmonic echocardiographic imaging on endocardial edge definition and side-lobe artifacts

    NASA Technical Reports Server (NTRS)

    Rubin, D. N.; Yazbek, N.; Garcia, M. J.; Stewart, W. J.; Thomas, J. D.

    2000-01-01

    Harmonic imaging is a new ultrasonographic technique that is designed to improve image quality by exploiting the spontaneous generation of higher frequencies as ultrasound propagates through tissue. We studied 51 difficult-to-image patients with blinded side-by-side cineloop evaluation of endocardial border definition by harmonic versus fundamental imaging. In addition, quantitative intensities from cavity versus wall were compared for harmonic versus fundamental imaging. Harmonic imaging improved left ventricular endocardial border delineation over fundamental imaging (superior: harmonic = 71.1%, fundamental = 18.7%; similar: 10.2%; P <.001). Quantitative analysis of 100 wall/cavity combinations demonstrated brighter wall segments and more strikingly darker cavities during harmonic imaging (cavity intensity on a 0 to 255 scale: fundamental = 15.6 +/- 8.6; harmonic = 6.0 +/- 5.3; P <.0001), which led to enhanced contrast between the wall and cavity (1.89 versus 1.19, P <.0001). Harmonic imaging reduces side-lobe artifacts, resulting in a darker cavity and brighter walls, thereby improving image contrast and endocardial delineation.

  12. Usefulness of ventricular endocardial electric reconstruction from body surface potential maps to noninvasively localize ventricular ectopic activity in patients

    NASA Astrophysics Data System (ADS)

    Lai, Dakun; Sun, Jian; Li, Yigang; He, Bin

    2013-06-01

    As radio frequency (RF) catheter ablation becomes increasingly prevalent in the management of ventricular arrhythmia in patients, an accurate and rapid determination of the arrhythmogenic site is of important clinical interest. The aim of this study was to test the hypothesis that the inversely reconstructed ventricular endocardial current density distribution from body surface potential maps (BSPMs) can localize the regions critical for maintenance of a ventricular ectopic activity. Patients with isolated and monomorphic premature ventricular contractions (PVCs) were investigated by noninvasive BSPMs and subsequent invasive catheter mapping and ablation. Equivalent current density (CD) reconstruction (CDR) during symptomatic PVCs was obtained on the endocardial ventricular surface in six patients (four men, two women, years 23-77), and the origin of the spontaneous ectopic activity was localized at the location of the maximum CD value. Compared with the last (successful) ablation site (LAS), the mean and standard deviation of localization error of the CDR approach were 13.8 and 1.3 mm, respectively. In comparison, the distance between the LASs and the estimated locations of an equivalent single moving dipole in the heart was 25.5 ± 5.5 mm. The obtained CD distribution of activated sources extending from the catheter ablation site also showed a high consistency with the invasively recorded electroanatomical maps. The noninvasively reconstructed endocardial CD distribution is suitable to predict a region of interest containing or close to arrhythmia source, which may have the potential to guide RF catheter ablation.

  13. Understanding the link between circumferential dikes and eruptive fissures around calderas based on numerical and analog models

    NASA Astrophysics Data System (ADS)

    Corbi, Fabio; Rivalta, Eleonora; Pinel, Virginie; Maccaferri, Francesco; Acocella, Valerio

    2016-06-01

    Active calderas are seldom associated with circumferential eruptive fissures, but eroded magmatic complexes reveal widespread circumferential dikes. This suggests that, while the conditions to emplace circumferential dikes are easily met, mechanisms must prevent them from reaching the surface. We explain this discrepancy with experiments of air injection into gelatin shaped as a volcano with caldera. Analog dikes show variable deflection, depending on the competition between overpressure, Pe, and topographic unloading, Pl; when Pl/Pe = 4.8-5.3, the dikes propagate orthogonal to the least compressive stress. Due to the unloading, they become circumferential and stall below the caldera rim; buoyancy is fundamental for the further rise and circumferential fissure development. Numerical models quantitatively constrain the stress orientation within the gelatin, explaining the observed circumferential dikes. Our results explain how dikes propagate below the rim of felsic and mafic calderas, but only in the latter they are prone to feed circumferential fissures.

  14. Steady and Unsteady Flow Effects of Circumferential Grooves Casing Treatment in a Transonic Compressor Rotor

    NASA Technical Reports Server (NTRS)

    Hah, Chunill

    2011-01-01

    The current paper reports on an investigation of steady and unsteady flow effects of circumferential grooves casing treatment in a transonic compressor rotor. Circumferential grooves casing treatment is used mainly to increase stall margin in axial compressors with a relatively small decrease in aerodynamic efficiency. It is widely believed that flow mechanisms of circumferential grooves casing treatment near stall conditions are not yet well understood even though this treatment has been used widely in real engines. Numerical analysis based on steady Reynolds-averaged Navier-Stokes (RANS) has been the primary tool used to understand flow mechanism for circumferential grooves casing treatment. Although steady RANS explains some flow effects of circumferential grooves casing treatment, it does not calculate all the measured changes in the compressor characteristics. Therefore, design optimization of circumferential grooves with steady RANS has not been very successful. As a compressor operates toward the stall condition, the flow field becomes transient. Major sources of self-generated flow unsteadiness are shock oscillation and interaction between the passage shock and the tip leakage vortex. In the present paper, an unsteady Reynolds-averaged Navier-Stokes (URANS) approach is applied to study the effects of circumferential grooves in a transonic compressor. The results from URANS are compared with the results from RANS and measured data. The current investigation shows that there are significant unsteady flow effects on the performance of the circumferential grooves casing treatment. For the currently investigated rotor, the unsteady effects are of the same magnitude as the steady effects in terms of extending the compressor stall margin.

  15. Circumferential decompression of the foramen magnum for the treatment of syringomyelia associated with basilar invagination.

    PubMed

    Collignon, Frederic P; Cohen-Gadol, Aaron A; Krauss, William E

    2004-07-01

    Posterior fossa decompression utilizing suboccipital craniectomy and duraplasty remains the standard surgical treatment for Chiari-associated syringomyelia. In the presence of basilar invagination, anterior decompression, typically transoral odontoidectomy, or posterior decompression may be performed. We report two cases in which anterior and posterior (circumferential) decompression of the foramen magnum was used to treat cervical syringomyelia successfully. These cases demonstrate that circumferential decompression of the foramen magnum may be necessary in some cases of cervical syringomyelia associated with basilar invagination and Chiari malformation.

  16. Toward Optimum Configuration of Circumferential Groove Casing Treatment in Transonic Compressor Rotors

    NASA Technical Reports Server (NTRS)

    Hah, Chunill

    2011-01-01

    The current paper first reviews experimental and numerical investigations to understand flow physics and to develop optimum configurations of circumferential grooves in compressor rotors. Circumferential grooves are used mainly to increase stall margin in axial compressors with small decrease in aerodynamic efficiency. Although circumferential groove casing treatment has been used widely, flow mechanisms of the circumferential grooves at near stall conditions are not well understood yet. Detailed time-dependent flow measurement inside tip gap in a high speed compressor is still a big challenge even though significant advance has been made in non-intrusive flow measurement technique. Therefore numerical approaches have been used to study relevant flow physics. However, optimum design of circumferential grooves to a given compressor with the computational tools is not practical yet. In the present paper, various investigations to study flow physics of circumferential groove casing treatment in axial compressor are reviewed first. Possible missing flow physics are identified and future research efforts for the optimum design are discussed.

  17. Circumferentially aligned fibers guided functional neoartery regeneration in vivo.

    PubMed

    Zhu, Meifeng; Wang, Zhihong; Zhang, Jiamin; Wang, Lina; Yang, Xiaohu; Chen, Jingrui; Fan, Guanwei; Ji, Shenglu; Xing, Cheng; Wang, Kai; Zhao, Qiang; Zhu, Yan; Kong, Deling; Wang, Lianyong

    2015-08-01

    An ideal vascular graft should have the ability to guide the regeneration of neovessels with structure and function similar to those of the native blood vessels. Regeneration of vascular smooth muscle cells (VSMCs) with circumferential orientation within the grafts is crucial for functional vascular reconstruction in vivo. To date, designing and fabricating a vascular graft with well-defined geometric cues to facilitate simultaneously VSMCs infiltration and their circumferential alignment remains a great challenge and scarcely reported in vivo. Thus, we have designed a bi-layered vascular graft, of which the internal layer is composed of circumferentially aligned microfibers prepared by wet-spinning and an external layer composed of random nanofibers prepared by electrospinning. While the internal circumferentially aligned microfibers provide topographic guidance for in vivo regeneration of circumferentially aligned VSMCs, the external random nanofibers can offer enhanced mechanical property and prevent bleeding during and after graft implantation. VSMCs infiltration and alignment within the scaffold was then evaluated in vitro and in vivo. Our results demonstrated that the circumferentially oriented VSMCs and longitudinally aligned ECs were successfully regenerated in vivo after the bi-layered vascular grafts were implanted in rat abdominal aorta. No formation of thrombosis or intimal hyperplasia was observed up to 3 month post implantation. Further, the regenerated neoartery exhibited contraction and relaxation property in response to vasoactive agents. This new strategy may bring cell-free small diameter vascular grafts closer to clinical application.

  18. The link between circumferential dikes and eruptive fissures around calderas: insights from numerical and analog models

    NASA Astrophysics Data System (ADS)

    Corbi, Fabio; Rivalta, Eleonora; Pinel, Virginie; Maccaferri, Francesco; Acocella, Valerio

    2016-04-01

    Active calderas are seldom associated with circumferential eruptive fissures along their rim, but eroded portions of extinct magmatic complexes reveal widespread evidence of circumferential dikes. This discrepancy suggests that, while the conditions to emplace circumferential dikes below volcanoes are easily met, mechanisms must exist to arrest the dikes before they reach the surface. Here we explain this discrepancy with laboratory experiments of air injection into a gelatin medium shaped to mimic a volcanic edifice with caldera. Our models show that the ascending dikes experience a variable degree of deflection, depending on the competition between dike overpressure, Pe, and the forcing induced by the topographic load, Pl. When Pl/Pe = 4.3 - 4.5 the analog dikes proceed almost insensitive to the stress rotation and erupt within the caldera. When Pl/Pe = 4.8 - 5.3 the analog dikes closely propagate orthogonal to the least compressive stress σ3 and stall below the caldera rim in a circumferential arrangement. Progressive buoyancy increase through repeated supply of fluid is fundamental for the occurrence of circumferential fissures. Complementary numerical models explain the observed circumferential arrangement and validate the experiments. These results contribute defining the shallow magma transfer and related hazard assessment within calderas.

  19. Segmental Analysis of Cardiac Short-Axis Views Using Lagrangian Radial and Circumferential Strain.

    PubMed

    Ma, Chi; Wang, Xiao; Varghese, Tomy

    2016-11-01

    Accurate description of myocardial deformation in the left ventricle is a three-dimensional problem, requiring three normal strain components along its natural axis, that is, longitudinal, radial, and circumferential strains. Although longitudinal strains are best estimated from long-axis views, radial and circumferential strains are best depicted in short-axis views. An algorithm that utilizes a polar grid for short-axis views previously developed in our laboratory for a Lagrangian description of tissue deformation is utilized for radial and circumferential displacement and strain estimation. Deformation of the myocardial wall, utilizing numerical simulations with ANSYS, and a finite-element analysis-based canine heart model were adapted as the input to a frequency-domain ultrasound simulation program to generate radiofrequency echo signals. Clinical in vivo data were also acquired from a healthy volunteer. Local displacements estimated along and perpendicular to the ultrasound beam propagation direction are then transformed into radial and circumferential displacements and strains using the polar grid based on a pre-determined centroid location. Lagrangian strain variations demonstrate good agreement with the ideal strain when compared with Eulerian results. Lagrangian radial and circumferential strain estimation results are also demonstrated for experimental data on a healthy volunteer. Lagrangian radial and circumferential strain tracking provide accurate results with the assistance of the polar grid, as demonstrated using both numerical simulations and in vivo study.

  20. Epicardial-endocardial breakthrough during stable atrial macroreentry: Evidence from ultra-high-resolution 3-dimensional mapping.

    PubMed

    Pathik, Bhupesh; Lee, Geoffrey; Sacher, Frédéric; Haïssaguerre, Michel; Jaïs, Pierre; Massoullié, Grégoire; Derval, Nicolas; Sanders, Prashanthan; Kistler, Peter; Kalman, Jonathan M

    2017-08-01

    Evidence for epicardial-endocardial breakthrough (EEB) is derived from mapping inferences in patients with atrial fibrillation who may also have focal activations. The purpose of this study was to investigate whether EEB could be discerned during stable right atrial (RA) macroreentry using high-density high-spatial resolution 3-dimensional mapping. Macroreentry was diagnosed using 3-dimensional mapping and entrainment. Bipolar maps were reviewed for EEB defined as (1) presence of focal endocardial activation with radial spread unaccounted for by an endocardial wavefront and (2) present with the same timing on every tachycardia cycle. The EEB site was always in proximity to a line of endocardial conduction slowing or block. Distance and conduction velocity from the line of block to the EEB site was calculated. Electrograms at EEB sites were individually analyzed for morphology and to confirm direction of activation. Entrainment was performed at EEB sites. Twenty-six patients were studied. Fourteen examples of EEB were seen: 11 at the posterior RA (4 at the superior portion of the posterior wall and 7 at the inferior section) and 1 each at the cavotricuspid isthmus postablation, RA septum, and inferolateral RA. The mean area of the EEB site was 0.6 ± 0.2 cm(2). A mean of 79.5% ± 18.6% of unipolar electrograms at the EEB site demonstrated an rS morphology. The mean distance and conduction velocity from the line of endocardial block to the EEB site at the posterior RA was 13.6 ± 2.3 mm and 59.3 ± 12.3 cm/s, respectively. In 4 patients, entrainment demonstrated that EEB sites were within the circuit and in 1 of these patients critical to arrhythmia maintenance. Activation maps during tachycardia and coronary sinus pacing demonstrated EEB at the same anatomic site. EEB sites were demonstrated in stable atrial macroreentry supported by systematic entrainment confirmation and demonstration of the same phenomenon during pacing. Copyright © 2017 Heart Rhythm Society

  1. Molecular analysis of the nondisjoined chromosome in trisomy 21 with and without endocardial cushion defects

    SciTech Connect

    Zittergruen, M.M.; Murray, J.C.; Lauer, R.M.

    1994-09-01

    Congenital heart disease is found in approximately 40% of patients with Down syndrome (DS), with endocardial cushion defects (ECDs) comprising one-third of the defects. Sixteen highly polymorphic microsatellite markers were typed in two groups (Group 1: DS with ECD, n=43, and Group 2: DS without ECD, n=52) to determine: (1) the parental origin of the extra chromosome, (2) the presence or absence of disomic homozygosity (reduced) or heterozygosity (nonreduced) of the markers along 21q, and (3) the presence or absence of recombination in the nondisjoined chromosome. The association of these three factors with the presence of ECD in DS was then determined. The origin of the nondisjoined chromosome was maternal in 86.3% of the total cases with no significant differences between groups 1 and 2. The most centromeric marker was nonreduced in 77% of the maternally-derived trisomies (indicative of a meiosis II nondisjunction) with no significant differences between groups 1 and 2. The most telomeric markers showed no differences in the number of reduced or nonreduced markers between maternally and paternally derived chromosomes or between groups 1 and 2. Recombination was significantly decreased in group 1 (28%) compared to group 2 (56%) (chi-square 7.45, p < 0.01) with similar values for both paternally and maternally-derived trisomies. Overall, recombination was present in 43.2% of the nondisjoined chromosomes which is similar to the 42.3% recombination reported in nondisjoined chromosomes in trisomy 21.

  2. Myopotential interference with DDD pacemakers: endocardial electrographic telemetry in the diagnosis of pacemaker-related arrhythmias.

    PubMed

    Halperin, J L; Camuñas, J L; Stern, E H; Rothlauf, E B; Kupersmith, J; Estioko, M R; Mace, R C; Steinmetz, M Y; Teichholz, L E

    1984-07-01

    Skeletal myopotentials may inhibit the output of unipolar demand ventricular pacemakers, resulting in protracted episodes of asystole in susceptible patients. The new DDD-mode pacemakers have, in addition to a unipolar ventricular lead, a unipolar atrial lead to enable atrioventricular sequential or atrial synchronous function. During clinical investigation of a new dual-unipolar cardiac pacing system programmed to operate in the DDD mode (Pacesetter AFP models 281 and 283), 6 patients were noted (5 men and 1 woman, aged 22 to 68 years) who manifested paroxysmal acceleration of ventricular pacing rate approaching the maximal tracking rate. Two patients also had abrupt slowing or cessation of ventricular output. With the use of atrial electrographic recordings (obtained with telemetry), the following mechanisms of rate change were found: myopotential tracking, myopotential inhibition, interference-mode asynchronous operation, sudden increases in sinus rate, and pacemaker-mediated reentrant tachycardia. In all patients, reprogramming of the implanted devices, based on telemetered atrial electrography, resulted in disappearance of the arrhythmias and loss of symptoms while maintaining the DDD pacing mode. Thus, several mechanisms of rhythm disturbances are peculiar to dual-chamber cardiac pacing systems that use unipolar electrodes. Endocardial telemetry combined with extensive programming capability offers the best opportunity for proper diagnosis and management of these problems.

  3. Correlation of scintigraphic phase maps with intraoperative epicardial/endocardial maps in patients with activation disturbances

    SciTech Connect

    Dae, M.W.; Botvinick, E.H.; Scheinmann, M.H.; Morady, F.J.; Davis, J.A.; Schechtmann, N.; Frais, M.; Faulkner, D.; O'Connell, W.

    1984-01-01

    To assess the true accuracy of scintigraphic findings, 8 patients (PTS), 6 with pre-excitation (PEX) syndrome and 2 with intractable ventricular tachycardia (VT), were studied by phase analysis, prior to corrective surgery. Sites of earliest phase angle were determined in multiple projections during the conduction disturbance, compared to sites of early ventricular activation determined by epicardial mapping during PEX and, when performed, by endocardial mapping during VT, and to maps previously generated at conventional electrophysiologic study (EPS). Among PEX PTS, Rt and Lt lateral, Lt anterolateral, Rt and Lt posterolateral and posteroseptal bypass pathways mapped at surgery correlated with phase localization. While localization from EPS also correlated well with surgical maps in 4 PTS, 1 PT could not be mapped by EPS and another presented ambiguities. Scintigraphic localization also correlated well with surgical mapping in a PT with a RV VT focus while EPS was suggestive but uncertain. A second PT with VT mapped scintigraphically to originate in a Lt lateral focus, demonstrated a similar localization on EPS, and during surgical mapping, an incision made through the scintigraphic focus terminated VT. Incision in regions of earliest activity in the first VT PT and in PTS with PEX resolved the arrhythmia or interrupted the bypass tract. Phase mapping correlated closely with surface mapping at surgery while providing an accurate, independent method for noninvasive assessment of conduction disturbances and a complementary tool to standard EPS.

  4. Beneficial Effect on Cardiac Resynchronization From Left Ventricular Endocardial Pacing Is Mediated by Early Access to High Conduction Velocity Tissue: Electrophysiological Simulation Study.

    PubMed

    Hyde, Eoin R; Behar, Jonathan M; Claridge, Simon; Jackson, Tom; Lee, Angela W C; Remme, Espen W; Sohal, Manav; Plank, Gernot; Razavi, Reza; Rinaldi, Christopher A; Niederer, Steven A

    2015-10-01

    Cardiac resynchronization therapy (CRT) delivered via left ventricular (LV) endocardial pacing (ENDO-CRT) is associated with improved acute hemodynamic response compared with LV epicardial pacing (EPI-CRT). The role of cardiac anatomy and physiology in this improved response remains controversial. We used computational electrophysiological models to quantify the role of cardiac geometry, tissue anisotropy, and the presence of fast endocardial conduction on myocardial activation during ENDO-CRT and EPI-CRT. Cardiac activation was simulated using the monodomain tissue excitation model in 2-dimensional (2D) canine and human and 3D canine biventricular models. The latest activation times (LATs) for LV endocardial and biventricular epicardial tissue were calculated (LVLAT and TLAT), as well the percentage decrease in LATs for endocardial (en) versus epicardial (ep) LV pacing (defined as %dLV=100×(LVLATep-LVLATen)/LVLATep and %dT=100×(TLATep-TLATen)/TLATep, respectively). Normal canine cardiac anatomy is responsible for %dLV and %dT values of 7.4% and 5.5%, respectively. Concentric and eccentric remodeled anatomies resulted in %dT values of 15.6% and 1.3%, respectively. The 3D biventricular-paced canine model resulted in %dLV and %dT values of -7.1% and 1.5%, in contrast to the experimental observations of 16% and 11%, respectively. Adding fast endocardial conduction to this model altered %dLV and %dT to 13.1% and 10.1%, respectively. Our results provide a physiological explanation for improved response to ENDO-CRT. We predict that patients with viable fast-conducting endocardial tissue or distal Purkinje network or both, as well as concentric remodeling, are more likely to benefit from reduced ATs and increased synchrony arising from endocardial pacing. © 2015 American Heart Association, Inc.

  5. High Rate of Positive Circumferential Resection Margins Following Rectal Cancer Surgery: A Call to Action

    PubMed Central

    Rickles, Aaron S.; Dietz, David W.; Chang, George J.; Wexner, Steven D.; Berho, Mariana E.; Remzi, Feza H.; Greene, Frederick L.; Fleshman, James W.; Abbas, Maher A.; Peters, Walter; Noyes, Katia; Monson, John R.T.; Fleming, Fergal J.

    2017-01-01

    Objective To identify predictors of positive circumferential resection margin following rectal cancer resection in the United States. Background Positive circumferential resection margin is associated with a high rate of local recurrence and poor morbidity and mortality for rectal cancer patients. Prior study has shown poor compliance with national rectal cancer guidelines, but whether this finding is reflected in patient outcomes has yet to be shown. Methods Patients who underwent resection for stage I-III rectal cancer were identified from the 2010-2011 National Cancer Database. The primary outcome was a positive circumferential resection margin. The relationship between patient, hospital, tumor, and treatment-related characteristics was analyzed using bivariate and multivariate analysis. Findings A positive circumferential resection margin was noted in 2,859 (17.2%) of the 16,619 patients included. Facility location, clinical T and N stage, histologic type, tumor size, tumor grade, lymphovascular invasion, perineural invasion, type of operation, and operative approach were significant predictors of positive circumferential resection margin on multivariable analysis. Total proctectomy had nearly a 30% increased risk of positive margin compared to partial proctectomy (OR 1.293, 95%CI 1.185-1.411) and a laparoscopic approach had nearly 22% less risk of a positive circumferential resection margin compared to an open approach (OR 0.882, 95%CI 0.790-0.985). Interpretation Despite advances in surgical technique and multimodality therapy, rates of positive circumferential resection margin remain high in the United States. Several tumor and treatment characteristics were identified as independent risk factors, and advances in rectal cancer care are necessary to approach the outcomes seen in other countries. PMID:26473651

  6. Task IV: Development of Circumferential Inlet Distortion through a Representative Eleven Stage High-speed Axial Compressor

    NASA Technical Reports Server (NTRS)

    Tan, Choon-Sooi; Suder, Kenneth (Technical Monitor)

    2003-01-01

    The concepts and the procedure developed in Task I and Task III were used to determine the response of an eleven-stage high-speed compressor to an inlet distortion of 180 deg. circumferential extent for contrasting against its performance under uniform inlet flow. Using the computed results at the inlet to and outlet of the compressor, the computed total pressure ratio and efficiency for the clean condition are determined to be 14.22 and 76.9 percent respectively. As for the distorted case, these are determined to be 10.35 and 71.8 percent respectively, showing deterioration 76.9 percent vs 71.8 percent). The physical consistency of the computed flow field was assessed as a means of demonstrating the applicability and utility of the body force representation for inlet distortion computations. Specifically the computed evolution of the distorted pattern in static pressure and total pressure from compressor inlet to exit is examined. For the eleven-stage compressor examined here, the deterioration in performance has been found to be particularly severe in the last 2 stages. This suggests that the last two stages could be redesigned to alleviate the observed deterioration thus making the compressor performance insensitive to circumferential inlet distortion. This can potentially be accomplished by first determining what should the body force distribution of the last two stages should be to achieve minimal or no deterioration in performance in the last two stages. One can then in principle proceed to determine the blade design to yield such a body force distribution.

  7. Comparison of three different pelvic circumferential compression devices: a biomechanical cadaver study.

    PubMed

    Knops, S P; Schep, N W L; Spoor, C W; van Riel, M P J M; Spanjersberg, W R; Kleinrensink, G J; van Lieshout, E M M; Patka, P; Schipper, I B

    2011-02-02

    Pelvic circumferential compression devices are designed to stabilize the pelvic ring and reduce the volume of the pelvis following trauma. It is uncertain whether pelvic circumferential compression devices can be safely applied for all types of pelvic fractures because the effects of the devices on the reduction of fracture fragments are unknown. The aim of this study was to compare the effects of circumferential compression devices on the dynamic realignment and final reduction of the pelvic fractures as a measure of the quality of reduction. Three circumferential compression devices were evaluated: the Pelvic Binder, the SAM Sling, and the T-POD. In sixteen cadavers, four fracture types were generated according to the Tile classification system. Infrared retroreflective markers were fixed in the different fracture fragments of each pelvis. The circumferential compression device was applied sequentially in a randomized order with gradually increasing forces applied. Fracture fragment movement was studied with use of a three-dimensional infrared video system. Dynamic realignment and final reduction of the fracture fragments during closure of the circumferential compression devices were determined. A factorial repeated-measures analysis of variance with pairwise post hoc comparisons was performed to analyze the differences in pulling force between the circumferential compression devices. In the partially stable and unstable (Tile type-B and C) pelvic fractures, all circumferential compression devices accomplished closure of the pelvic ring and consequently reduced the pelvic volume. No adverse fracture displacement (>5 mm) was observed in these fracture types. The required pulling force to attain complete reduction at the symphysis pubis varied substantially among the three different circumferential compression devices, with a mean (and standard error of the mean) of 43 ± 7 N for the T-POD, 60 ± 9 N for the Pelvic Binder, and 112 ± 10 N for the SAM Sling. The

  8. Clinical evaluation of peak endocardial acceleration as a sensor for rate responsive pacing.

    PubMed

    Greco, Enrico Maria; Ferrario, Marco; Romano, Salvatore

    2003-04-01

    An innovative control parameter for rate responsive (RR) pacing that uses a sensor to measure mechanical vibrations generated by the myocardium during the isovolumetric contraction phase (peak endocardial acceleration [PEA]), has been devised by SORIN Biomedica (BEST Living System). To assess the physiological sensitivity of the pacemaker sensor along with reliability of the algorithm to supply appropriate pacing rates three different relationships were examined (linear regression analysis): (1) recorded deltaPEA exercise steps against the calculated energy cost of exercise (MET), (2) exercise pacing rates against predicted values, and (3) deltaPEA against exercise pacing rates. Fifteen patients (mean age 68 +/- 12 years) in NYHA Class I-II, implanted with the BEST Living System (Living 1 DDDR pacemaker) for advanced AVB and/or SSS, underwent one of the following maximal exercise stress protocols: bicycle (25 W, 2-minute steps) or Bruce or Chronotropic Assessment Exercise Protocol (CAEP). Pacing rates for each step were matched against those predicted by a reliable and tested custom software called Pacing Rate Profile Software (PRPS). The PRPS is based on the oxygen pulse reserve (OPR) method (OPR = VO2 reserve divided by heart rate reserve), American College of Sports Medicine (ACSM) formulas for calculating workload/metabolic requirements, and data derived from the Weber functional classes. On the basis of certain patient, data the PRPS then supplies appropriate metabolic pacing rate profiles. In all 15 patients linear regression analysis of deltaPEA against MET, as evaluated during the exercise protocol steps, showed a high correlation (r = 0.97). Likewise, a high correlation was also obtained between PRPS predicted heart rates and exercise pacing rates (r = 0.96) and PEA against exercise pacing rates (r = 0.96). The results of this study show that, through PEA dynamic monitoring, the SORIN Best Living System produces physiological pacing rates that are

  9. A review on the safety of one-stage circumferential ring constriction release.

    PubMed

    Prasetyono, Theddeus O H; Sitorus, Ade S N

    2015-02-01

    The study was undertaken to investigate the use of one-stage circumferential ring-constriction release with Z-plasties regarding the safety, aesthetic appearance, and limb function. A thorough review was conducted on all English publications in PubMed during the period of 2001 through 2011. Titles and abstracts were identified using online search engine from National Library of Medicine's PubMed database under the keywords "limb constriction ring," "limb constriction band," "amniotic band," "annular constriction," and "circumferential constriction." We used Boolean operator and field of title. Evaluation was done to search indications, timing of the first surgical intervention, time interval between surgeries, patients' gender, anatomic location of the ring, wound healing problems, and scar quality. Fourteen publications met the criteria. There were 17 patients with 25 ring constrictions in total. Sixteen ring constrictions (64%) were circumferential; nine (36%) were semi-circumferential. Mean age of 14 patients treated with one-stage release was 4.8 years. Six articles mentioned about normal development of postoperative limb function. Mean age of three patients treated with staged release was 10.5 months. Two articles mentioned regained distal muscle function postoperatively. It is confirmed that surgeons may continue the practice to release circumferential CRS in one stage.

  10. Repeat left atrial catheter ablation: cardiac magnetic resonance prediction of endocardial voltage and gaps in ablation lesion sets.

    PubMed

    Harrison, James L; Sohns, Christian; Linton, Nick W; Karim, Rashed; Williams, Steven E; Rhode, Kawal S; Gill, Jaswinder; Cooklin, Michael; Rinaldi, C Aldo; Wright, Matthew; Schaeffter, Tobias; Razavi, Reza S; O'Neill, Mark D

    2015-04-01

    Studies have reported an inverse relationship between late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) signal intensity and left atrial (LA) endocardial voltage after LA ablation. However, there is controversy regarding the reproducibility of atrial LGE CMR and its ability to identify gaps in ablation lesions. Using systematic and objective techniques, this study examines the correlation between atrial CMR and endocardial voltage. Twenty patients who had previous ablation for atrial fibrillation and represented with paroxysmal atrial fibrillation or atrial tachycardia underwent preablation LGE CMR. During the ablation procedure, high-density point-by-point Carto voltage maps were acquired. Three-dimensional CMR reconstructions were registered with the Carto anatomies to allow comparison of voltage and LGE signal intensity. Signal intensities around the left and right pulmonary vein antra and along the LA roof and mitral lines on the CMR-segmented LA shells were extracted to examine differences between electrically isolated and reconnected lesions. There were a total of 6767 data points across the 20 patients. Only 119 (1.8%) of the points were ≤ 0.05 mV. There was only a weak inverse correlation between either unipolar (r = -0.18) or bipolar (r = -0.17) voltage and LGE CMR signal intensities with low voltage occurring across a large range of signal intensities. Signal intensities were not statistically different for electrically isolated and reconnected lesions. This study demonstrates that there is only a weak point-by-point relationship between LGE CMR and endocardial voltage in patients undergoing repeat LA ablation. Using an objective method of assessing gaps in ablation lesions, LGE CMR is unable to reliably predict sites of electrical conduction. © 2015 American Heart Association, Inc.

  11. Hybrid epicardial and endocardial ablation of persistent or permanent atrial fibrillation: a new approach for difficult cases.

    PubMed

    Pak, Hui-Nam; Hwang, Chun; Lim, Hong Euy; Kim, Jin Seok; Kim, Young-Hoon

    2007-09-01

    Although percutaneous epicardial catheter ablation (PECA) has been used for the management of epicardial ventricular tachycardia, the use of PECA for atrial fibrillation (AF) has not yet been reported. To evaluate the efficacy and feasibility of a hybrid PECA and endocardial ablation for AF. We performed PECA for AF in five patients (48.6 +/- 8.1 years old, all male, four redo ablation procedures of persistent AF with a risk of pulmonary vein (PV) stenosis, one de novo ablation of permanent [AF]) after an endocardial AF ablation guided by PV potentials and 3D mapping (NavX). Utilizing an open irrigation tip catheter, a left atrial (LA) linear ablation from the roof to the perimitral isthmus or localized ablation at the junction between the LA appendage and left-sided PVs or ligament of Marshall (LOM) was performed. PECA of AF was successful in all patients with an ablation time of <15 minutes. The left-sided PV potentials were eliminated by PECA in all patients. Bidirectional block of the perimitral line was achieved in two of two patients and a left inferior PV tachycardia with conduction block to the LA was observed during the ablation in the area of the LOM in one patient. A hemopericardium developed in one patient, but was controlled successfully. During 8.0 +/- 6.3 months of follow-up, all patients have remained in sinus rhythm (four patients without antiarrhythmic drugs). A hybrid PECA of AF is feasible and effective in patients with redo-AF ablation procedures and at risk for left-sided PV stenosis or who are resistant to endocardial linear ablation.

  12. Distribution of excitation frequencies on the epicardial and endocardial surfaces of fibrillating ventricular wall of the sheep heart.

    PubMed

    Zaitsev, A V; Berenfeld, O; Mironov, S F; Jalife, J; Pertsov, A M

    2000-03-03

    Tissue heterogeneities may play an important role in the mechanism of ventricular tachycardia (VT) and fibrillation (VF) and can lead to a complex spatial distribution of excitation frequencies. Here we used optical mapping and Fourier analysis to determine the distribution of excitation frequencies in >20 000 sites of fibrillating ventricular tissue. Our objective was to use such a distribution as a tool to quantify the degree of organization during VF. Fourteen episodes of VT/VF were induced via rapid pacing in 9 isolated, coronary perfused, and superfused sheep ventricular slabs (3x3 cm(2)). A dual-camera video-imaging system was used for simultaneous optical recordings from the entire epi- and endocardial surfaces. The local frequencies of excitation were determined at each pixel and displayed as dominant frequency (DF) maps. A typical DF map consisted of several (8.2+/-3.6) discrete areas (domains) with a uniform DF within each domain. The DFs in adjacent domains were often in 1:2, 3:4, or 4:5 ratios, which was shown to be a result of an intermittent Wenckebach-like conduction block at the domain boundaries. The domain patterns were relatively stable and could persist from several seconds to several minutes. The complexity in the organization of the domains, the number of domains, and the dispersion of frequencies increased with the rate of the arrhythmia. Domain patterns on the epicardial and endocardial surfaces were not correlated. Sustained epicardial or endocardial reentry was observed in only 3 episodes. Observed frequency patterns during VT/VF suggest that the underlying mechanism may be a sustained intramural reentrant source interacting with tissue heterogeneities.

  13. Quantification of the Transmural Dynamics of Atrial Fibrillation by Simultaneous Endocardial and Epicardial Optical Mapping in an Acute Sheep Model

    PubMed Central

    Gutbrod, Sarah R.; Walton, Richard; Gilbert, Stephen; Meillet, Valentin; Jaïs, Pierre; Hocini, Mélèze; Haïssaguerre, Michel; Dubois, Rémi; Bernus, Olivier; Efimov, Igor

    2015-01-01

    Background Therapy strategies for atrial fibrillation based on electrical characterization are becoming viable personalized medicine approaches to treat a notoriously difficult disease. In light of these approaches that rely on high-density surface mapping, this study aims to evaluate the presence of three-dimensional electrical substrate variations within the transmural wall during acute episodes of atrial fibrillation Methods and Results Optical signals were simultaneously acquired from the epicardial and endocardial tissue during acute fibrillation in ovine isolated left atria. Dominant frequency, regularity index, propagation angles and phase dynamics were assessed and correlated across imaging planes to gauge the synchrony of the activation patterns compared to paced rhythms. Static frequency parameters were well correlated spatially between the endocardium and the epicardium (dominant frequency, 0.79±0.06 and regularity index, 0.93±0.009). However, dynamic tracking of propagation vectors and phase singularity trajectories revealed discordant activity across the transmural wall. The absolute value of the difference in the number, spatial stability, and temporal stability of phase singularities between the epicardial and endocardial planes was significantly greater than 0 with a median difference of 1.0, 9.27%, and 19.75%, respectively. The number of wavefronts with respect to time was significantly less correlated and the difference in propagation angle was significantly larger in fibrillation compared to paced rhythms. Conclusion Atrial fibrillation substrates are dynamic three-dimensional structures with a range of discordance between the epicardial and endocardial tissue. The results of this study suggest that transmural propagation may play a role in AF maintenance mechanisms. PMID:25713215

  14. Circumferential periosteal sleeve resection for limb length inequality complicated by growth plate tether.

    PubMed

    Al Hussainy, H A J; Jones, S; Ali, F; Davies, A G

    2004-09-01

    Correction of limb length inequality can be achieved by stimulation of growth of the short limb. Circumferential periosteal sleeve resection has been reported as a safe and reliable method of stimulating longitudinal bone growth. We report the complication of growth tethers to the distal tibial physes in two patients following circumferential periosteal sleeve resection to the distal femur, tibia and fibula. This was done under direct vision. This complication may have arisen due to damage to the perichondrial ring as a result of raising the periosteum too close to the distal tibial physes. A limited response may be seen in young patients following this procedure as a result of this complication. Circumferential periosteal sleeve resection for limb length inequality is a treatment option that is not without complication.

  15. Evidence for hydrated spermidine-calf thymus DNA toruses organized by circumferential DNA wrapping.

    PubMed Central

    Marx, K A; Ruben, G C

    1983-01-01

    In spermidine-condensed calf thymus DNA preparations, torus-shaped condensates were shown by transmission electron microscopy to exist under the hydrated conditions of the freeze fracture experiment. Using extremely low Pt metal deposition levels (9 A Pt/C) high-contrast replicas of the spermidine-DNA toruses were obtained that showed circumferential wrapping of single DNA double helix-size surface fibres. Stereoscopic analysis of high magnification stereomicrographs established some details of the three-dimensional organization of two DNA double helix sections winding circumferentially on the inner surface of one such torus. These measurements demonstrate the usefulness of stereoscopic analysis of these high macromolecular organization magnification. Measurements on a number of torus-shaped complexes (n = 16) yielded these average dimensions: inner circumference (1840 +/- 204 A) outer circumference (2800 +/- 222 A), torus ring thickness (143 +/- 18 A). These data support a continuous circumferential DNA-winding model of torus organization proposed by Marx & Reynolds. Images PMID:6835840

  16. Application of induced circumferential current for cracks inspection on pipe string

    NASA Astrophysics Data System (ADS)

    Yuan, Xin'an; Li, Wei; Yin, Xiaokang; Chen, Guoming; Ge, Jiuhao

    2016-02-01

    Pipe strings (such as drill pipe, tube, pipeline, riser) are critical facilities in oil & gas industry, which are highly susceptible to cracks caused by stress corrosion and fatigue damage. The most common defects are longitudinal and transverse surface cracks on pipe strings in oil & gas industry. Conventional nondestructive testing (NDT) methods are inadequate for these surface cracks on pipe strings. In this paper, a full 360° circumferential current induced by a coaxial excitation coil is present for inspection of longitudinal and transverse surface cracks on pipe strings. The finite element method (FEM) is employed to obtain characteristics signals by analyzing the distorted electromagnetic field above the cracks. The induced circumferential current test system is set up and crack inspection experiments are carried out. The results show that both longitudinal and transverse surface cracks can be detected effectively at one pass scanning on pipe string using the induced circumferential current.

  17. Self-Reacting Friction Stir Welding for Aluminum Alloy Circumferential Weld Applications

    NASA Technical Reports Server (NTRS)

    Bjorkman, Gerry; Cantrell, Mark; Carter, Robert

    2003-01-01

    Friction stir welding is an innovative weld process that continues to grow in use, in the commercial, defense, and space sectors. It produces high quality and high strength welds in aluminum alloys. The process consists of a rotating weld pin tool that plasticizes material through friction. The plasticized material is welded by applying a high weld forge force through the weld pin tool against the material during pin tool rotation. The high weld forge force is reacted against an anvil and a stout tool structure. A variation of friction stir welding currently being evaluated is self-reacting friction stir welding. Self-reacting friction stir welding incorporates two opposing shoulders on the crown and root sides of the weld joint. In self-reacting friction stir welding, the weld forge force is reacted against the crown shoulder portion of the weld pin tool by the root shoulder. This eliminates the need for a stout tooling structure to react the high weld forge force required in the typical friction stir weld process. Therefore, the self-reacting feature reduces tooling requirements and, therefore, process implementation costs. This makes the process attractive for aluminum alloy circumferential weld applications. To evaluate the application of self-reacting friction stir welding for aluminum alloy circumferential welding, a feasibility study was performed. The study consisted of performing a fourteen-foot diameter aluminum alloy circumferential demonstration weld using typical fusion weld tooling. To accomplish the demonstration weld, weld and tack weld development were performed and fourteen-foot diameter rings were fabricated. Weld development consisted of weld pin tool selection and the generation of a process map and envelope. Tack weld development evaluated gas tungsten arc welding and friction stir welding for tack welding rings together for circumferential welding. As a result of the study, a successful circumferential demonstration weld was produced leading

  18. Aerodynamic Inner Workings of Circumferential Grooves in a Transonic Axial Compressor

    NASA Technical Reports Server (NTRS)

    Hah, Chunill; Mueller, Martin; Schiffer, Heinz-Peter

    2007-01-01

    The current paper reports on investigations of the fundamental flow mechanisms of circumferential grooves applied to a transonic axial compressor. Experimental results show that the compressor stall margin is significantly improved with the current set of circumferential grooves. The primary focus of the current investigation is to advance understanding of basic flow mechanics behind the observed improvement of stall margin. Experimental data and numerical simulations of a circumferential groove were analyzed in detail to unlock the inner workings of the circumferential grooves in the current transonic compressor rotor. A short length scale stall inception occurs when a large flow blockage is built on the pressure side of the blade near the leading edge and incoming flow spills over to the adjacent blade passage due to this blockage. The current study reveals that a large portion of this blockage is created by the tip clearance flow originating from 20% to 50% chord of the blade from the leading edge. Tip clearance flows originating from the leading edge up to 20% chord form a tip clearance core vortex and this tip clearance core vortex travels radially inward. The tip clearance flows originating from 20% to 50% chord travels over this tip clearance core vortex and reaches to the pressure side. This part of tip clearance flow is of low momentum as it is coming from the casing boundary layer and the blade suction surface boundary layer. The circumferential grooves disturb this part of the tip clearance flow close to the casing. Consequently the buildup of the induced vortex and the blockage near the pressure side of the passage is reduced. This is the main mechanism of the circumferential grooves that delays the formation of blockage near the pressure side of the passage and delays the onset of short length scale stall inception. The primary effect of the circumferential grooves is preventing local blockage near the pressure side of the blade leading edge that

  19. Compact MEMS-driven pyramidal polygon reflector for circumferential scanned endoscopic imaging probe.

    PubMed

    Mu, Xiaojing; Zhou, Guangya; Yu, Hongbin; Du, Yu; Feng, Hanhua; Tsai, Julius Ming Lin; Chau, Fook Siong

    2012-03-12

    A novel prototype of an electrothermal chevron-beam actuator based microelectromechanical systems (MEMS) platform has been successfully developed for circumferential scan. Microassembly technology is utilized to construct this platform, which consists of a MEMS chevron-beam type microactuator and a micro-reflector. The proposed electrothermal microactuators with a two-stage electrothermal cascaded chevron-beam driving mechanism provide displacement amplification, thus enabling a highly reflective micro-pyramidal polygon reflector to rotate a large angle for light beam scanning. This MEMS platform is ultra-compact, supports circumferential imaging capability and is suitable for endoscopic optical coherence tomography (EOCT) applications, for example, for intravascular cancer detection.

  20. Feasibility study of negative lift circumferential type seal for helicopter transmissions

    NASA Technical Reports Server (NTRS)

    Goldring, E. N.

    1977-01-01

    A new seal concept, the negative lift circumferential type seal, was evaluated under simulated helicopter transmission conditions. The bore of the circumferential seal contains step type geometry which produces a negative lift that urges the sealing segments towards the shaft surface. The seal size was a 2.5 inch bore and the test speeds were 7000 and 14,250 rpm. During the 300 hour test at typical transmission seal pressure (to 2 psig) the leakage was within acceptable limits and generally less than 0.1 cc/hour during the last 150 hours of testing. The wear to the carbon segments during the 300 hours was negligible.

  1. Complete 360° circumferential gonioscopic optical coherence tomography imaging of the iridocorneal angle

    PubMed Central

    McNabb, Ryan P.; Challa, Pratap; Kuo, Anthony N.; Izatt, Joseph A.

    2015-01-01

    Clinically, gonioscopy is used to provide en face views of the ocular angle. The angle has been imaged with optical coherence tomography (OCT) through the corneoscleral limbus but is currently unable to image the angle from within the ocular anterior chamber. We developed a novel gonioscopic OCT system that images the angle circumferentially from inside the eye through a custom, radially symmetric, gonioscopic contact lens. We present, to our knowledge, the first 360° circumferential volumes (two normal subjects, two subjects with pathology) of peripheral iris and iridocorneal angle structures obtained via an internal approach not typically available in the clinic. PMID:25909021

  2. A second patient with MCA/MR syndrome with multiple circumferential skin creases.

    PubMed

    Leonard, N J

    2002-09-15

    Symmetrical congenital circumferential skin creases are a rare feature described in only a few conditions. We report a case of a 29-month-old boy with symmetrical circumferential skin creases on arms, legs, and digits, and other features reminiscent of the single case reported by Cohen et al. [1993: Clin Dysmorphol 2:39-46] and reviewed by Elliott et al. [1996: Am J Med Genet 62:23-25]. The key features also include epicanthic folds, microphthalmia, microcornea, microcephaly, small, low-set posteriorly angulated ears with thick overfolded helices, cleft palate, and moderate-severe psychomotor developmental delay.

  3. Characterization of circumferential guided waves in a cylindrical cortical bone-mimicking phantom.

    PubMed

    Nauleau, Pierre; Cochard, Etienne; Minonzio, Jean-Gabriel; Grimal, Quentin; Laugier, Pascal; Prada, Claire

    2012-04-01

    The femoral neck cortical shell was recently demonstrated to act like a waveguide for circumferential waves. Femoral neck assessment with ultrasound could be enhanced by guided waves measurement. In this study, the decomposition of the time reversal operator (DORT) method is used to measure the phase velocities of circumferential guided modes in a circular tube with dimensions characteristic of femoral neck. The tube is made of a bone-mimicking material. Five guided modes are obtained and compared to theoretical predictions. The work substantiates the feasibility of measuring guided waves in a relatively thick tube of attenuating material with the DORT method.

  4. Code System for Fracture Mechanics Analysis of Circumferential Surface Cracks in Pipes.

    SciTech Connect

    BRUST, F.

    1999-07-28

    Version 00 The NRCPIPES software is designed to perform elastic and elastic-plastic fracture mechanics analysis for a circumferential surface cracked pipe, i.e., to establish the fracture-failure condition in terms of sustainable load (or stress) or displacement. The NRCPIPES software also includes several evaluation procedures and acceptance criteria for circumferential surface flaws based on the ASME Boiler and Pressure Vessel Code, Section XI criteria, the British R6 Revision 3 Option 1 criteria, and the original Net-Section-Collapse (limit-load) analysis.

  5. Apoptosis in the left ventricle of chronic volume overload causes endocardial endothelial dysfunction in rats.

    PubMed

    Cox, Michael J; Sood, Harpreet S; Hunt, Matthew J; Chandler, Derrick; Henegar, Jeffrey R; Aru, Giorgio M; Tyagi, Suresh C

    2002-04-01

    the oxidative stress and generation of nitrotyrosine are, in part, responsible for the activation of metalloproteinase and decreased endocardial endothelial function in chronic LV volume overload.

  6. Fetal echocardiographic assessment of endocardial fibroelastosis in maternal anti-SSA antibody-associated complete heart block.

    PubMed

    Aoki, Hisaaki; Inamura, Noboru; Kawazu, Yukiko; Nakayama, Masahiro; Kayatani, Futoshi

    2011-01-01

    There are few reports describing the features of maternal anti-SSA antibody-associated congenital complete heart block (CCHB) patients developing endocardial fibroelastosis (EFE). The aim of this study was to describe the clinical features and the outcome of patients with CCHB, with or without EFE. Over a 20-year period, 12 consecutive patients diagnosed with maternal anti-SSA antibody-associated CCHB were identified. The maternal anti-SSA antibody levels were measured and fetal echocardiographic findings were reviewed. The ratios of the thickness of the endocardium to that of the whole wall of the left ventricle (LE/W) and right ventricle (RE/W) were measured to investigate the degree of endocardial thickening. A total of 7 patients survived (living group) and were not diagnosed as having EFE. The remaining 5 patients died and were diagnosed with EFE during autopsy (dead group). Fetal echocardiography of the patients showed differences in the thickening and hyperintensity of the endocardium. The RE/W value was significantly higher in the dead group than in the living group. The titers of both maternal anti-52-kDa and anti-60-kDa SSA antibodies were high, but showed no significant differences between the 2 patient groups. EFE was the major negative prognostic factor for CCHB. Myocardial damage, predominantly in the right ventricle, was related to the outcome of CCHB associated with EFE.

  7. Arteries respond to independent control of circumferential and shear stress in organ culture.

    PubMed

    Wayman, Brian H; Taylor, W Robert; Rachev, Alexander; Vito, Raymond P

    2008-05-01

    Arteries respond to changes in global mechanical parameters (pressure, flow rate, and longitudinal stretching) by remodeling to restore local parameters (circumferential stress, shear stress, and axial strain) to baseline levels. Because a change in a single global parameter results in changes of multiple local parameters, the effects of individual local parameters on remodeling remain unknown. This study uses a novel approach to study remodeling in organ culture based on independent control of local mechanical parameters. The approach is illustrated by studying the short term effects of circumferential and shear stress on remodeling-related biological markers. Porcine carotid arteries were cultured for 3 days at a circumferential stress of 50 or 150 kPa or, in separate experiments, a shear stress of 0.75 or 2.25 Pa. At high circumferential stress, matrix synthesis, smooth muscle cell proliferation, and cell death are significantly greater, but matrix metalloproteinase-2 (MMP-2) and pro-MMP-2 activity are significantly less. In contrast, biological markers measured were unaffected by shear stress. Applications of the proposed approach for improved understanding of remodeling, optimizing mechanical conditioning of tissue engineered arteries, and selection of experimentally motivated growth laws are discussed.

  8. MEMS-based non-rotatory circumferential scanning optical probe for endoscopic optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Xu, Yingshun; Singh, Janak; Siang, Teo Hui; Ramakrishna, Kotlanka; Premchandran, C. S.; Sheng, Chen Wei; Kuan, Chuah Tong; Chen, Nanguang; Olivo, Malini C.; Sheppard, Colin J. R.

    2007-07-01

    In this paper, we present a non-rotatory circumferential scanning optical probe integrated with a MEMS scanner for in vivo endoscopic optical coherence tomography (OCT). OCT is an emerging optical imaging technique that allows high resolution cross-sectional imaging of tissue microstructure. To extend its usage to endoscopic applications, a miniaturized optical probe based on Microelectromechanical Systems (MEMS) fabrication techniques is currently desired. A 3D electrothermally actuated micromirror realized using micromachining single crystal silicon (SCS) process highlights its very large angular deflection, about 45 degree, with low driving voltage for safety consideration. The micromirror is integrated with a GRIN lens into a waterproof package which is compatible with requirements for minimally invasive endoscopic procedures. To implement circumferential scanning substantially for diagnosis on certain pathological conditions, such as Barret's esophagus, the micromirror is mounted on 90 degree to optical axis of GRIN lens. 4 Bimorph actuators that are connected to the mirror on one end via supporting beams and springs are selected in this micromirror design. When actuators of the micromirror are driven by 4 channels of sinusoidal waveforms with 90 degree phase differences, beam focused by a GRIN is redirected out of the endoscope by 45 degree tilting mirror plate and achieve circumferential scanning pattern. This novel driving method making full use of very large angular deflection capability of our micromirror is totally different from previously developed or developing micromotor-like rotatory MEMS device for circumferential scanning.

  9. Variations of mechanical property of out circumferential lamellae in cortical bone along the radial by nanoindentation

    NASA Astrophysics Data System (ADS)

    Sun, Xingdong; Zhao, Hongwei; Yu, Yang; Zhang, Shizhong; Ma, Zhichao; Li, Ning; Yu, Miao; Hou, Pengliang

    2016-11-01

    Because the out circumferential lamellae have a special protective effect on the cortical bone, it is very important to understand the variations of the mechanical property of the out circumferential lamellae in cortical bone. For the purpose, the elasticity modulus and hardness of out circumferential lamellae in cortical bone were investigated in two orthogonal planes by nanoindentation, and the comparisons were made for both elasticity modulus and hardness between the two orthogonal planes. From the experiments, the decreasing trend was discovered for elasticity modulus from inside to outside in the transverse plane and ruleless variations tendency was presented in the longitudinal plane. The hardness presented the same variations in two orthogonal planes with elasticity modulus in respective plane. In the same layer, the elasticity modulus in the transverse plane was higher than that in the longitudinal plane, and the difference values between them turned to be smaller. In contrast, the hardness in the longitudinal plane was higher than that in the transverse plane in all the layers. From the heterogeneity and the microstructure of the material, the influence factors were discussed. A soft to hard structure model was put forward, and the coordinating protection mechanism of buffer and support was described. Investigation of variations of mechanical properties of out circumferential lamellae in cortical bone can provide some new understanding in researches of fracture of bone, interface load effect and design of bone graft.

  10. Circumferential optical coherence tomography angiography imaging of the swine esophagus using a micromotor balloon catheter

    PubMed Central

    Lee, Hsiang-Chieh; Ahsen, Osman Oguz; Liang, Kaicheng; Wang, Zhao; Cleveland, Cody; Booth, Lucas; Potsaid, Benjamin; Jayaraman, Vijaysekhar; Cable, Alex E.; Mashimo, Hiroshi; Langer, Robert; Traverso, Giovanni; Fujimoto, James G.

    2016-01-01

    We demonstrate a micromotor balloon imaging catheter for ultrahigh speed endoscopic optical coherence tomography (OCT) which provides wide area, circumferential structural and angiographic imaging of the esophagus without contrast agents. Using a 1310 nm MEMS tunable wavelength swept VCSEL light source, the system has a 1.2 MHz A-scan rate and ~8.5 µm axial resolution in tissue. The micromotor balloon catheter enables circumferential imaging of the esophagus at 240 frames per second (fps) with a ~30 µm (FWHM) spot size. Volumetric imaging is achieved by proximal pullback of the micromotor assembly within the balloon at 1.5 mm/sec. Volumetric data consisting of 4200 circumferential images of 5,000 A-scans each over a 2.6 cm length, covering a ~13 cm2 area is acquired in <18 seconds. A non-rigid image registration algorithm is used to suppress motion artifacts from non-uniform rotational distortion (NURD), cardiac motion or respiration. En face OCT images at various depths can be generated. OCT angiography (OCTA) is computed using intensity decorrelation between sequential pairs of circumferential scans and enables three-dimensional visualization of vasculature. Wide area volumetric OCT and OCTA imaging of the swine esophagus in vivo is demonstrated. PMID:27570688

  11. Circumferential burns to the fingers associated with gold and platinum rings.

    PubMed

    Regan, M W; Moss, A L

    1986-06-01

    Two patients sustained circumferential burns to the fingers associated with metal rings. The first case was caused by molten zinc and was treated by early burn excision and split skin grafting, while the second case was an electrical burn caused by a car battery and was treated conservatively.

  12. Expanded plug method for developing circumferential mechanical properties of tubular materials

    DOEpatents

    Hendrich, William Ray; McAfee, Wallace Jefferson; Luttrell, Claire Roberta

    2006-11-28

    A method for determining the circumferential properties of a tubular product, especially nuclear fuel cladding, utilizes compression of a polymeric plug within the tubular product to determine strain stress, yield stress and other properties. The process is especially useful in the determination of aging properties such as fuel rod embrittlement after long burn-down.

  13. Optimization of the axial compressor flow passage to reduce the circumferential distortion

    NASA Astrophysics Data System (ADS)

    Popov, G.; Kolmakova, D.; Shklovets, A.; Ermakov, A.

    2015-08-01

    This work is motivated by the necessity to reduce the effects of the flow circumferential distortion in the flow passage of the aircraft gas turbine engine (GTE). In previous research, the authors have proposed the approaches to decrease of the flow circumferential distortion arising from the mid-support racks of GTE compressor and having a negative impact on the blade rows, located upstream. In particular, the idea of introducing the circumferentially non-uniform blade pitch and profile stagger angle of guide vanes located in front of the support was contributed in order to redistribute the flow and decrease the dynamic stresses in the rotor wheel of the same stage. During the research presented in this paper, another principal of reduction of the flow circumferential distortion was chosen. Firstly, the variants of upgrading the existing support racks were found. Secondly, the new design of support was offered. Both the first and the second version of the support design variation took into account the availability of technological and structural limitations associated with the location of oil pipes, springs and others elements in the support racks. Investigations of modified design showed that the support with altered racks provides a reduction of dynamic stresses by 20% at resonance with the most dangerous harmonic, and the new design of support can give the decrease of 30%.

  14. Saturn S-11 Production Operations Techniques, Production Welding. Volume 3: Circumferential Welding

    NASA Technical Reports Server (NTRS)

    Abel, D. G.

    1970-01-01

    Special processes and techniques are described for the circumferential welding of Saturn 2 cylinder and bulkhead assemblies to complete the LO2 and LH2 tankage and to maximize efficiency and personnel performance during S-2 follow-on or restart activities. The processes are only applicable to aluminum alloys within the 2000 series.

  15. Molecular Modeling of the Axial and Circumferential Elastic Moduli of Tubulin

    PubMed Central

    Zeiger, A. S.; Layton, B. E.

    2008-01-01

    Microtubules play a number of important mechanical roles in almost all cell types in nearly all major phylogenetic trees. We have used a molecular mechanics approach to perform tensile tests on individual tubulin monomers and determined values for the axial and circumferential moduli for all currently known complete sequences. The axial elastic moduli, in vacuo, were found to be 1.25 GPa and 1.34 GPa for α- and β-bovine tubulin monomers. In the circumferential direction, these moduli were 378 MPa for α- and 460 MPa for β-structures. Using bovine tubulin as a template, 269 homologous tubulin structures were also subjected to simulated tensile loads yielding an average axial elastic modulus of 1.10 ± 0.14 GPa for α-tubulin structures and 1.39 ± 0.68 GPa for β-tubulin. Circumferentially the α- and β-moduli were 936 ± 216 MPa and 658 ± 134 MPa, respectively. Our primary finding is that that the axial elastic modulus of tubulin diminishes as the length of the monomer increases. However, in the circumferential direction, no correlation exists. These predicted anisotropies and scale dependencies may assist in interpreting the macroscale behavior of microtubules during mitosis or cell growth. Additionally, an intergenomic approach to investigating the mechanical properties of proteins may provide a way to elucidate the evolutionary mechanical constraints imposed by nature upon individual subcellular components. PMID:18621829

  16. A method for measuring mean circumferential fiber shortening rate from gated blood pool scans.

    PubMed

    Bhargava, V; Costello, D; Slutsky, R; Verba, J

    1982-01-01

    Ejection fraction and ejection rate are easily obtained from gated cardiac images, but no method is available for calculating mean circumferential fiber shortening rate. We assumed that the cube root of left ventricular end-diastolic volume or counts is proportional to the minor axis of the left ventricle at end-diastole or end-systole. Mean circumferential fiber shortening rate is then equal to the [cube root of the end-diastolic volume (count) minus cube root of end-systolic volume (count)] divided by [cube root of end-diastolic volume (count) multiplied by the ejection time]. In 250 contrast ventriculograms, the standard mean circumferential fiber shortening rate (MCFSR) and that derived by the cube root method correlated well (r = 0.94). The mean value of MCFSR (0.85 +/- 0.35) was greater than the cube root value (0.75 +/- 0.35) (P less than 0.001). The regression equation was y = 0.86x + 0.02. Similar correlations were obtained from gated radionuclide images using a semiautomated program (r = 0.93) in 24 subjects or completely automated program (r = 0.85) in 28 patients. The regression equation between MCFSR and that derived from the cube root of counts for the semiautomated program was y = 0.82x + 0.04 and for the automated program was y = 0.84x + 0.004. Similar correlations, slopes, and intercepts were seen using circumferential fractional shortening for angiographic data when correlated with both the semiautomated and automated gated blood pool scan programs. These data indicate that MCFSR and circumferential fractional shortening may be obtained from gated blood pool images using cube root estimates of end-diastolic and end-systolic radii with a high degree of correlation with the standard contrast ventriculographic technique.

  17. Can magnetic resonance imaging predict circumferential margins and TNM stage in rectal cancer?

    PubMed

    Branagan, Graham; Chave, Helen; Fuller, Clare; McGee, Shaun; Finnis, Derek

    2004-08-01

    This study was designed to assess whether preoperative magnetic resonance imaging scans were able to predict 1) pathologic tumor and node stage, and 2) those patients with a pathologically clear circumferential resection margin. Patients with histologically proven carcinoma of the rectum were staged preoperatively using magnetic resonance imaging. Histologic specimens from patients undergoing mesorectal excision were reported according to the Royal College of Pathologists minimum dataset. Agreement between radiologic staging of tumor, local lymph nodes and circumferential resection margin involvement, and pathologic reporting was assessed by means of the Kappa statistic. After exclusions (10 radiotherapy, 3 failed scans, 10 no surgery, 9 local surgery), 40 patients remained. Magnetic resonance imaging correctly staged the tumor in 20 patients, understaged in 12, and overstaged in 8. Statistically, there was poor correlation between pathologic and radiologic tumor staging (Kappa, 0.18; 95 percent confidence interval, -0.13 to 0.42). Magnetic resonance imaging correctly staged node status in 27 patients, overstaged in 9, and understaged in 4. Statistically, there was poor correlation between pathologic and radiologic node staging (Kappa, 0.38; 95 percent confidence interval, 0.08-0.64). Magnetic resonance imaging correctly reported the status of the circumferential resection margin in 39 patients and understaged 1. Statistically, there was good correlation between pathologic and radiologic reporting of circumferential resection margin involvement (Kappa, 0.66; 95 percent confidence interval, 0.03-1). Preoperative magnetic resonance imaging scans provide poor predictive data as to subsequent pathologic tumor and node stage. Preoperative magnetic resonance imaging does produce reliable prediction of clear circumferential resection margins and provides valuable information in assessing whether patients can proceed to surgery without the need for preoperative

  18. Mucosal breaks show same circumferential distribution in majority of patients with recurrent reflux esophagitis

    PubMed Central

    Fukuda, Naoki; Ishimura, Norihisa; Okada, Mayumi; Izumi, Daisuke; Mikami, Hironobu; Okimoto, Eiko; Aimi, Masahito; Mishiro, Tsuyoshi; Oshima, Naoki; Ishihara, Shunji; Kinoshita, Yoshikazu

    2017-01-01

    Background and study aims Esophageal mucosal breaks in patients with reflux esophagitis (RE) have a unique circumferential distribution. However, the specific location of mucosal breaks during recurrence of RE remains unclear. We investigated the circumferential distribution of mucosal breaks in patients with recurrent RE and compared their location to that noted at the initial diagnosis. Patients and methods We retrospectively enrolled patients with recurrent RE with Los Angeles (LA) grade A-C who were treated at our University Hospital between July 1996 and June 2014. The circumferential distribution of esophageal mucosal breaks was evaluated at the time of the initial diagnosis and again at the time of recurrence. Information regarding clinical parameters, including proton pump inhibitor administration, presence of hiatal hernia, and mucosal atrophy, was also reviewed. Results A total of 114 patients with recurrent RE were examined during the study period, with a mean duration to recurrence after initial diagnosis of 39.4 months. The majority (72.8 %) had the same LA grade at recurrence. In addition, recurrent mucosal breaks in 96 (84.2 %) patients were observed to have occurred in the same circumferential location as at the initial diagnosis, while those in 18 (15.8 %) were observed in a different location. When recurrent lesions had a different location, the LA grade also tended to be different (P = 0.02). Conclusions We found that most patients with recurrent RE developed lesions in the same circumferential location as noted for the initial lesions. Those in different locations at recurrence were associated with a change in LA grade. PMID:28317018

  19. Zebrafish Crip2 plays a critical role in atrioventricular valve development by downregulating the expression of ECM genes in the endocardial cushion.

    PubMed

    Kim, Jun-Dae; Kim, Hey-Jin; Koun, Soonil; Ham, Hyung-Jin; Kim, Myoung-Jin; Rhee, Myungchull; Huh, Tae-Lin

    2014-05-01

    The initial step of atrioventricular (AV) valve development involves the deposition of extracellular matrix (ECM) components of the endocardial cushion and the endocardial-mesenchymal transition. While the appropriately regulated expression of the major ECM components, Versican and Hyaluronan, that form the endocardial cushion is important for heart valve development, the underlying mechanism that regulates ECM gene expression remains unclear. We found that zebrafish crip2 expression is restricted to a subset of cells in the AV canal (AVC) endocardium at 55 hours post-fertilization (hpf). Knockdown of crip2 induced a heart-looping defect in zebrafish embryos, although the development of cardiac chambers appeared to be normal. In the AVC of Crip2-deficient embryos, the expression of both versican a and hyaluronan synthase 2 (has2) was highly upregulated, but the expression of bone morphogenetic protein 4 (bmp4) and T-box 2b (tbx2b) in the myocardium and of notch1b in the endocardium in the AVC did not change. Taken together, these results indicate that crip2 plays an important role in AV valve development by downregulating the expression of ECM components in the endocardial cushion.

  20. Elbow Reconstruction With Compression Plate Arthrodesis and Circumferential Muscle-Sparing Latissimus Dorsi Flap After Tumor Resection

    PubMed Central

    Ng, Zhi Yang; Ramachandran, Savitha; Tan, Bien-Keem; Foo, Leon; Ng, Siew-Weng

    2016-01-01

    Background: The goals of limb-sparing surgery in the setting of extremity malignancies are 2-fold: oncological clearance and the rehabilitation of function and aesthetics. Treatment success should be defined by the extent of restoration of the patient’s premorbid function for reintegration into society. Methods: We would like to report an unusual case of a patient with a chronically ankylosed elbow with joint invasion by basal cell carcinoma which resulted from malignant transformation of an overlying, long-standing wound due to inadequately treated septic arthritis from his childhood years. Results: Following R0 resection, upper limb shortening and compression plate elbow arthrodesis were performed with the aim of restoring the degree of upper limb function that the patient had been accustomed to preoperatively. The resultant circumferential defect was then closed with a contralateral, free muscle-sparing latissimus dorsi flap. Conclusions: Functional preservation may therefore be more important than the mere restoration of anatomical defects in these especially challenging situations. PMID:27418897

  1. Endo-epicardial versus only-endocardial ablation as a first line strategy for the treatment of ventricular tachycardia in patients with ischemic heart disease.

    PubMed

    Izquierdo, Maite; Sánchez-Gómez, Juan Miguel; Ferrero de Loma-Osorio, Angel; Martínez, Angel; Bellver, Alejandro; Peláez, Antonio; Núñez, Julio; Núñez, Carlos; Chorro, Javier; Ruiz-Granell, Ricardo

    2015-08-01

    Epicardial ablation has shown improvement in clinical outcomes of patients with ischemic heart disease (IHD) after ventricular tachycardia (VT) ablation. However, usually epicardial access is only performed when endocardial ablation has failed. Our aim was to compare the efficacy of endocardial+epicardial ablation versus only endocardial ablation in the first procedure in patients with IHD. Fifty-three patients with IHD, referred for a first VT ablation to our institution, from 2012 to 2014, were included. They were divided in 2 groups according to enrollment time: from May 2013, we started to systematically perform endo-epicardial access (Epi-Group) as first-line approach in consecutive patients with IHD (n=15). Patients who underwent only an endocardial VT ablation in their first procedure (Endo-Group) included patients with previous cardiac surgery and the historical (before May 2013; n=35). All late-potentials in the scar zone were eliminated, and if VT was tolerated, critical isthmuses were also approached. The end point was the noninducibility of any VT. During a median follow-up of 15±10 months, the combined end point (hospital or emergency admission because of a ventricular tachycardia or reablation) occurred in 14 patients of the Endo-group and in one patient in the Epi-group (event-free survival curves by Grey-test, P=0.03). Ventricular arrhythmia recurrences occurred in 16 and in 3 patients in the Endo and Epi-Group, respectively (Grey-test, P=0.2). A combined endocardial-epicardial ablation approach for initial VT ablation was associated with fewer readmissions for VT and repeat ablations. Further studies are warranted. © 2015 American Heart Association, Inc.

  2. Circumferential myocardial strain in cardiomyopathy with and without left bundle branch block

    PubMed Central

    2010-01-01

    Background Cardiac resynchronization therapy (CRT) has been shown to decrease mortality in 60-70% of advanced heart failure patients with left bundle branch block (LBBB) and QRS duration > 120 ms. There have been intense efforts to find reproducible non-invasive parameters to predict CRT response. We hypothesized that different left ventricular contraction patterns may exist in LBBB patients with depressed systolic function and applied tagged cardiovascular magnetic resonance (CMR) to assess circumferential strain in this population. Methods We determined myocardial circumferential strain at the basal, mid, and apical ventricular level in 35 subjects (10 with ischemic cardiomyopathy, 15 with non-ischemic cardiomyopathy, and 10 healthy controls). Patterns of circumferential strain were analyzed. Time to peak systolic circumferential strain in each of the 6 segments in all three ventricular slices and the standard deviation of time to peak strain in the basal and mid ventricular slices were determined. Results Dyskinesis of the anterior septum and the inferior septum in at least two ventricular levels was seen in 50% (5 out of 10) of LBBB patients while 30% had isolated dyskinesis of the anteroseptum, and 20% had no dyskinesis in any segments, similar to all of the non-LBBB patients and healthy controls. Peak circumferential strain shortening was significantly reduced in all cardiomyopathy patients at the mid-ventricular level (LBBB 9 ± 6%, non-LBBB 10 ± 4% vs. healthy 19 ± 4%; both p < 0.0001 compared to healthy), but was similar among the LBBB and non-LBBB groups (p = 0.20). The LBBB group had significantly greater dyssynchrony compared to the non-LBBB group and healthy controls assessed by opposing wall delays and 12-segment standard deviation (LBBB 164 ± 30 ms vs. non-LBBB 70 ± 17 ms (p < 0.0001), non-LBBB vs. healthy 65 ± 17 ms (p = 0.47)). Conclusions Septal dyskinesis exists in some patients with LBBB. Myocardial circumferential strain analysis enables

  3. Circumferential myocardial strain in cardiomyopathy with and without left bundle branch block.

    PubMed

    Han, Yuchi; Chan, Jonathan; Haber, Idith; Peters, Dana C; Zimetbaum, Peter J; Manning, Warren J; Yeon, Susan B

    2010-01-05

    Cardiac resynchronization therapy (CRT) has been shown to decrease mortality in 60-70% of advanced heart failure patients with left bundle branch block (LBBB) and QRS duration > 120 ms. There have been intense efforts to find reproducible non-invasive parameters to predict CRT response. We hypothesized that different left ventricular contraction patterns may exist in LBBB patients with depressed systolic function and applied tagged cardiovascular magnetic resonance (CMR) to assess circumferential strain in this population. We determined myocardial circumferential strain at the basal, mid, and apical ventricular level in 35 subjects (10 with ischemic cardiomyopathy, 15 with non-ischemic cardiomyopathy, and 10 healthy controls). Patterns of circumferential strain were analyzed. Time to peak systolic circumferential strain in each of the 6 segments in all three ventricular slices and the standard deviation of time to peak strain in the basal and mid ventricular slices were determined. Dyskinesis of the anterior septum and the inferior septum in at least two ventricular levels was seen in 50% (5 out of 10) of LBBB patients while 30% had isolated dyskinesis of the anteroseptum, and 20% had no dyskinesis in any segments, similar to all of the non-LBBB patients and healthy controls. Peak circumferential strain shortening was significantly reduced in all cardiomyopathy patients at the mid-ventricular level (LBBB 9 +/- 6%, non-LBBB 10 +/- 4% vs. healthy 19 +/- 4%; both p < 0.0001 compared to healthy), but was similar among the LBBB and non-LBBB groups (p = 0.20). The LBBB group had significantly greater dyssynchrony compared to the non-LBBB group and healthy controls assessed by opposing wall delays and 12-segment standard deviation (LBBB 164 +/- 30 ms vs. non-LBBB 70 +/- 17 ms (p < 0.0001), non-LBBB vs. healthy 65 +/- 17 ms (p = 0.47)). Septal dyskinesis exists in some patients with LBBB. Myocardial circumferential strain analysis enables detailed characterization of

  4. Segmentation of the endocardial wall of the left atrium using local region-based active contours and statistical shape learning

    NASA Astrophysics Data System (ADS)

    Gao, Yi; Gholami, Behnood; MacLeod, Robert S.; Blauer, Joshua; Haddad, Wassim M.; Tannenbaum, Allen R.

    2010-03-01

    Atrial fibrillation, a cardiac arrhythmia characterized by unsynchronized electrical activity in the atrial chambers of the heart, is a rapidly growing problem in modern societies. One treatment, referred to as catheter ablation, targets specific parts of the left atrium for radio frequency ablation using an intracardiac catheter. Magnetic resonance imaging has been used for both pre- and and post-ablation assessment of the atrial wall. Magnetic resonance imaging can aid in selecting the right candidate for the ablation procedure and assessing post-ablation scar formations. Image processing techniques can be used for automatic segmentation of the atrial wall, which facilitates an accurate statistical assessment of the region. As a first step towards the general solution to the computer-assisted segmentation of the left atrial wall, in this paper we use shape learning and shape-based image segmentation to identify the endocardial wall of the left atrium in the delayed-enhancement magnetic resonance images.

  5. Endocardial or epicardial ventricular tachycardia in nonischemic cardiomyopathy? The role of 12-lead ECG criteria in clinical practice.

    PubMed

    Piers, Sebastiaan R D; Silva, Marta de Riva; Kapel, Gijsbert F L; Trines, Serge A; Schalij, Martin J; Zeppenfeld, Katja

    2014-06-01

    Specific 12-lead ECG criteria have been reported to predict an epicardial site of origin (SoO) of induced ventricular tachycardias (VTs) in left ventricular nonischemic cardiomyopathy. The purpose of this study was to (1) determine the value of ECG criteria to predict an epicardial SoO of clinically documented VTs, (2) analyze the effect of VT cycle length (CL) and antiarrhythmic drugs on the accuracy of ECG criteria, and (3) assess interobserver variability. In 36 consecutive patients with nonischemic left ventricular cardiomyopathy (age 58 ± 16 years, 75% male) who underwent combined endocardial/epicardial VT ablation, all clinically documented and induced right bundle branch block VTs were analyzed for previously reported ECG criteria to determine the SoO, as defined by ≥11/12 pace-map, concealed entrainment, and/or VT termination during ablation. In 21 patients with clinically documented (25 mm/s) right bundle branch block VT, none of the ECG criteria differentiated between patients with and those without an epicardial SoO. In induced VTs (100 mm/s), 2 of 4 interval criteria differentiated between an endocardial and epicardial SoO for slow VTs (CL >350 ms) and 2 of 4 criteria in patients on amiodarone, but none for fast VTs (CL ≤350 ms) or patients off amiodarone. The Q wave in lead I was the most accurate criterion for an epicardial SoO (sensitivity 88%, specificity 80%). In both clinically documented and induced VTs, interobserver agreement was poor for pseudodelta wave and moderate for other criteria. When applied to clinically documented VTs, no ECG criterion could differentiate between patients with and those without an epicardial SoO. Published interval-based ECG criteria do not apply to fast VTs and patients off amiodarone. Copyright © 2014 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  6. Measurement of dispersion curves of circumferential guided waves radiating from curved shells: Theory and numerical validation.

    PubMed

    Chekroun, Mathieu; Minonzio, Jean-Gabriel; Prada, Claire; Laugier, Pascal; Grimal, Quentin

    2016-02-01

    A method is proposed to evaluate in a non-contact way the phase velocity dispersion curves of circumferential waves around a shell of arbitrary shape immersed in a fluid. No assumptions are made about the thickness or the material of the shell. A geometrical model is derived to describe the shape of the radiated wavefronts in the surrounding fluid, and predict the positions of its centers of curvature. Then the time-reversal principle is applied to recover these positions and to calculate the phase velocity of the circumferential waves. Numerical finite-difference simulations are performed to evaluate the method on a circular and on an elliptic thin shell. Different dispersion curves can be recovered with an error of less than 10%.

  7. Skin resurfacing in a circumferential full thickness burn to the penis: lessons learnt

    PubMed Central

    Jabir, Shehab; Frew, Quentin; Thompson, Richard; Dziewulski, Peter

    2013-01-01

    A circumferential full-thickness burn to the penis is a rarely encountered injury. However, when it does occur, it proves a management challenge to the plastic and burns surgeon in terms of reconstruction. This is due to the need of not only regaining adequate function of the organ, but also because of the need for a pleasing aesthetic outcome. Split-skin grafts have been utilised successfully to resurface full thickness burns of the penis and have given good results. Yet the success of split-skin grafts, especially those applied to an anatomically challenging region of the body such as the penis, depends on a number of carefully thought-out steps. We discuss the case of a circumferential full-thickness burn to the penis which was treated with split-skin grafting and highlight important pitfalls that the plastic and burns surgeon need to be aware of to ensure a successful outcome. PMID:23946511

  8. Head and neck swelling due to a circumferential cicatricial scar in a dog.

    PubMed

    Westermeyer, Hans D; Tobias, Karen M; Reel, Danielle R

    2009-01-01

    A 4-year-old, castrated male, mixed-breed dog was evaluated because of progressive head swelling, exercise intolerance, and increasing respiratory effort of 1 month's duration. Physical examination and radiographs revealed severe edema of the head and face that was cranial to a circumferential, midcervical constriction caused by scarring related to previous removal of a foreign body. Surgical en bloc resection of the cicatricial tissue was performed, and clinical signs resolved completely after 2 months. Histopathology showed ongoing inflammation and hairs within a fibrous band. This case emphasizes that incomplete wound debridement may lead to excessive fibrous tissue proliferation and that thorough wound examination and debridement should be performed after removing circumferential cervical foreign bodies to ensure complete healing.

  9. Assessment of accumulated damage in circular tubes using nonlinear circumferential guided wave approach: A feasibility study.

    PubMed

    Deng, Mingxi; Gao, Guangjian; Xiang, Yanxun; Li, Mingliang

    2017-03-01

    The feasibility of using the nonlinear effect of primary Circumferential Guided Wave (CGW) propagation for assessing accumulated damage in circular tubes has been investigated. For a given circular tube, an appropriate mode pair of fundamental and double frequency CGWs is chosen to enable that the second harmonic of the primary wave mode can accumulate along the circumferential direction. After the given circular tube is subjected to compression-compression repeated loading for different numbers of loading cycles, the corresponding ultrasonic measurements are conducted. It is found that there is a direct correlation between the acoustic nonlinearity parameter measured with CGWs propagating through one full circumference and the level of accumulated damage in the circular tube. The experimental result obtained validates the feasibility for quantitative assessment of the accumulated damage in circular tubes using the effect of second-harmonic generation by CGW propagation.

  10. Evaluation of circumferential airflow uniformity entering combustors from compressors. Volume 1: Discussion of data and results

    NASA Technical Reports Server (NTRS)

    Shadowen, J. H.; Egan, W. J., Jr.

    1972-01-01

    The compressor discharge airflow uniformity of two compressors from advanced engines, the J58 and F100/F401, was studied. Compressor discharge pressures and temperatures at up to 33 circumferential rake locations allowed the airflow distribution to be ascertained and computer plotted. Several flight conditions and compressor variables, i.e., inlet distortion, modified seals, etc., were analyzed. An unexpectedly high nonuniform airflow was found for both compressors. Circumferential airflow deviation differences of up to 52% from maximum to minimum were found for the J58, and up to 40% for the F100/F401. The effects of aerodynamic and thermal distortion were found to be additive. The data were analyzed for influence of exit guide vane wakes and found free of any effect. Data system errors were small in relation to the measured pressure and temperature variations.

  11. Skin resurfacing in a circumferential full thickness burn to the penis: lessons learnt.

    PubMed

    Jabir, Shehab; Frew, Quentin; Thompson, Richard; Dziewulski, Peter

    2013-08-13

    A circumferential full-thickness burn to the penis is a rarely encountered injury. However, when it does occur, it proves a management challenge to the plastic and burns surgeon in terms of reconstruction. This is due to the need of not only regaining adequate function of the organ, but also because of the need for a pleasing aesthetic outcome. Split-skin grafts have been utilised successfully to resurface full thickness burns of the penis and have given good results. Yet the success of split-skin grafts, especially those applied to an anatomically challenging region of the body such as the penis, depends on a number of carefully thought-out steps. We discuss the case of a circumferential full-thickness burn to the penis which was treated with split-skin grafting and highlight important pitfalls that the plastic and burns surgeon need to be aware of to ensure a successful outcome.

  12. A "watch window" technique for monitoring buried free jejunum flaps during circumferential pharyngolaryngectomy reconstruction.

    PubMed

    Li, Quan; Zhang, Xin-Rui; Liu, Xue-Kui; Zhang, Zhi-Gang; Liu, Wei-Wei; Li, Hao; Guo, Zhu-Ming

    2012-07-01

    The free jejunum flap approach is the optimal option for circumferential pharyngolaryngectomy reconstruction. In this study, we designed a "watch window" for monitoring buried free jejunum flaps, thereby allowing us to assess graft viability. From 2007 to 2011, 14 patients with hypopharyngeal cancer underwent circumferential pharyngolaryngectomy that was reconstructed using a free jejunum flap at the Sun Yat-sen University Cancer Centre. During the closing of the neck incision, a "watch window" was designed for postoperative monitoring. Two patients experienced thrombosis of the pedicle. One was detected early and successfully rescued by removal of the thrombosis, the other one managed with a second free jejunum flap. The success rate of the buried flaps was 92.9%. No pharyngocutaneous fistulas or strictures occurred. All patients eventually resumed oral feeding and swallowing. The "watch window" technique for monitoring buried free jejunum flaps is simple, reliable and useful for finding vascular problems. Level of evidence Case series.

  13. Guided waves based diagnostic imaging of circumferential cracks in small-diameter pipe.

    PubMed

    Liu, Kehai; Wu, Zhanjun; Jiang, Youqiang; Wang, Yishou; Zhou, Kai; Chen, Yingpu

    2016-02-01

    To improve the safety and reliability of pipeline structures, much work has been done using ultrasonic guided waves methods for pipe inspection. Though good for evaluating the defects in the pipes, most of the methods lack the capability to precisely identify the defects in the pipe features like welds or supports. Therefore, a novel guided wave based cross-sectional diagnostic imaging algorithm was developed to improve the ability of circumferential cracks identification in the pipe features. To ensure the accuracy of the imaging, an angular profile-based frequency selection method is presented. As validation, the approach was employed to identify the presence and location of a small circumferential crack with 1.13% cross sectional area (CSA) in the welding zone of a 48 mm diameter type 304 stainless steel pipe. Accurate identification results have demonstrated the effectiveness of the developed approach. Copyright © 2015. Published by Elsevier B.V.

  14. Symptoms in severe aortic stenosis are associated with decreased compensatory circumferential myocardial mechanics.

    PubMed

    Carasso, Shemy; Mutlak, Diab; Lessick, Jonathan; Reisner, Shimon A; Rakowski, Harry; Agmon, Yoram

    2015-02-01

    Symptomatic patients with severe aortic stenosis (AS) demonstrate abnormal left ventricular (LV) mechanics. The aim of this study was to compare mechanics in asymptomatic and symptomatic patients with severe AS using two-dimensional myocardial strain imaging. One hundred fifty-four patients with severe AS (aortic valve area ≤ 1.0 cm(2)) referred to a heart valve clinic from 2004 to 2011 were studied. Thirty patients were asymptomatic, with normal LV ejection fractions (≥ 55%), without other significant valvular disease or wall motion abnormalities. Thirty-two symptomatic patients who underwent early aortic valve replacement, with similar age, gender, LV ejection fraction, and aortic valve area, were selected for comparison. Both groups were also compared with 32 healthy subjects with similar age and gender distributions and normal echocardiographic results who served as controls. LV longitudinal and circumferential strain and rotation were measured using speckle-tracking software applied to archived echocardiographic studies. Conventional echocardiographic and myocardial mechanical parameters were compared among the study subgroups. Patients with asymptomatic severe AS demonstrated smaller reductions in longitudinal strain, higher (supernormal) apical circumferential strain (-38 ± 6% vs -35 ± 4%, P < .05), and extreme (supernormal) apical rotation (12.2 ± 4.9° vs 2.9 ± 1.7°, P < .0005) compared with symptomatic patients. Apical rotation < 6° was the single significant predictor of symptoms in logistic regression analysis of clinical, echocardiographic, and mechanical parameters. Twelve asymptomatic patients underwent eventual aortic valve replacement and showed decreases in strain and apical rotation compared with baseline values. Longitudinal strain was uniformly low in patients with severe AS and lower in those with symptoms. Compensatory circumferential myocardial mechanics (increased apical circumferential strain and rotation) were absent in

  15. The elasticity problem for a thick-walled cylinder containing a circumferential crack

    NASA Technical Reports Server (NTRS)

    Nied, H. F.; Erdogan, F.

    1982-01-01

    The elasticity problem for a long hollow circular cylinder containing an axisymmetric circumferential crack subjected to general nonaxisymmetric external loads is considered. The problem is formulated in terms of a system of singular integral equations with the Fourier coefficients of the derivative of the crack surface displacement as density functions. The stress intensity factors and the crack opening displacement are calculated for a cylinder under uniform tension, bending by end couples, and self-equilibrating residual stresses.

  16. Role of circumferential flow in the stability of fluid-handling machine rotors

    NASA Technical Reports Server (NTRS)

    Bently, D. E.; Muszynska, A.

    1989-01-01

    The recent studies of the dynamic stiffness properties of fluid lubricated bearing and seals by the authors have yielded most of the generalized characteristics discussed and used in this paper. They include bearing and seal nonlinear fluid film properties associated with stiffness, damping, and fluid average circumferential velocity ratio. Analytical relationships yield the rotor system's dynamic stiffness characteristics. This paper shows the combination of these data to provide the fluid-induced rotor stability equations.

  17. Ligation-assisted endoscopic submucosal resection with circumferential mucosal incision for duodenal carcinoid tumor.

    PubMed

    Harada, Hideaki; Suehiro, Satoshi; Shimizu, Takanori; Katsuyama, Yasushi; Hayasaka, Kenji; Ito, Hideto

    2015-09-14

    Here we present the case of a 64-year-old female with a duodenal carcinoid tumor treated by ligation-assisted endoscopic submucosal resection (ESMR-L) with circumferential mucosal incision (CMI). Band ligation was effective in resecting the duodenal carcinoid tumor after CMI, with an uneventful post-procedural course. Histopathological examination showed clear tumor margins at deeper tissue levels. Thus, in the present case, ESMR-L with CMI was useful for the treatment of duodenal carcinoid tumor.

  18. Use of circumferential stapler in reconstruction following resections for carcinoma of the cardia.

    PubMed

    Molina, J E; Lawton, B R; Avance, D

    1981-04-01

    The use of the End-to-End Anastomosis (EEA) circumferential stapler for reconstruction following resection of the esophagus and stomach for carcinoma of the cardia is reported here in 9 consecutive patients with fifteen anastomoses performed with this unit. The technical aspects of the EEA stapler are emphasized. Two frequent problems associated with this type of operation namely, stenosis or leak at the suture line, are completely avoided by the use of this stapler unit. Its use is recommended.

  19. Autologous gluteal augmentation with circumferential body lift in the massive weight loss and aesthetic patient.

    PubMed

    Centeno, Robert F

    2006-07-01

    Massive weight loss (MWL) patients have unique and severe gluteal deformities that demand alternative body contouring solutions because they are rarely candidates for gluteal implants. Techniques for autologous gluteal augmentation (AGA) with circumferential body lift (CBL) are offered as a solution to this problem. Experience with these techniques will allow surgeons to extend AGA to other aesthetic patients presenting with flattened buttocks. Flap indications, surgical planning, techniques,results, complications, and postoperative management are discussed.

  20. Ligation-assisted endoscopic submucosal resection with circumferential mucosal incision for duodenal carcinoid tumor

    PubMed Central

    Harada, Hideaki; Suehiro, Satoshi; Shimizu, Takanori; Katsuyama, Yasushi; Hayasaka, Kenji; Ito, Hideto

    2015-01-01

    Here we present the case of a 64-year-old female with a duodenal carcinoid tumor treated by ligation-assisted endoscopic submucosal resection (ESMR-L) with circumferential mucosal incision (CMI). Band ligation was effective in resecting the duodenal carcinoid tumor after CMI, with an uneventful post-procedural course. Histopathological examination showed clear tumor margins at deeper tissue levels. Thus, in the present case, ESMR-L with CMI was useful for the treatment of duodenal carcinoid tumor. PMID:26379409

  1. Influence of the heart rate on mean circumferential shortening velocity: echocardiographic study of 183 normal subjects.

    PubMed

    Mangiarotti, R; Martinotti, R; Monzani, V; Sardella, F; Pierini, A; Pastori, M; Randazzo, A

    1986-01-01

    Echocardiography was used to explore the influence of independent variables (age, body surface area and heart rate) on the mean circumferential shortening velocity (MVCF) in 183 healthy subjects. Multiple stepwise regression analysis shows that heart rate is the only variable of the three just mentioned that influences MVCF. A regression equation is evolved and proposed as an index of MVCF correction for varying heart rates.

  2. Different contribution of extent of myocardial injury to left ventricular systolic and diastolic function in early reperfused acute myocardial infarction

    PubMed Central

    2014-01-01

    Background We sought to investigate the influence of the extent of myocardial injury on left ventricular (LV) systolic and diastolic function in patients after reperfused acute myocardial infarction (AMI). Methods Thirty-eight reperfused AMI patients underwent cardiac magnetic resonance (CMR) imaging after percutaneous coronary revascularization. The extent of myocardial edema and scarring were assessed by T2 weighted imaging and late gadolinium enhancement (LGE) imaging, respectively. Within a day of CMR, echocardiography was done. Using 2D speckle tracking analysis, LV longitudinal, circumferential strain, and twist were measured. Results Extent of LGE were significantly correlated with LV systolic functional indices such as ejection fraction (r = -0.57, p < 0.001), regional wall motion score index (r = 0.52, p = 0.001), and global longitudinal strain (r = 0.56, p < 0.001). The diastolic functional indices significantly correlated with age (r = -0.64, p < 0.001), LV twist (r = -0.39, p = 0.02), average non-infarcted myocardial circumferential strain (r = -0.52, p = 0.001), and LV end-diastolic wall stress index (r = -0.47, p = 0.003 with e’) but not or weakly with extent of LGE. In multivariate analysis, age and non-infarcted myocardial circumferential strain independently correlated with diastolic functional indices rather than extent of injury. Conclusions In patients with timely reperfused AMI, not only extent of myocardial injury but also age and non-infarcted myocardial function were more significantly related to LV chamber diastolic function. PMID:24512272

  3. Circumferential alignment of vascular smooth muscle cells in a circular microfluidic channel.

    PubMed

    Choi, Jong Seob; Piao, Yunxian; Seo, Tae Seok

    2014-01-01

    The circumferential alignment of human aortic smooth muscle cells (HASMCs) in an orthogonally micropatterned circular microfluidic channel is reported to form an in vivo-like smooth muscle cell layer. To construct a biomimetic smooth muscle cell layer which is aligned perpendicular to the axis of blood vessel, a half-circular polydimethylsiloxane (PDMS) microchannel is first fabricated by soft lithography using a convex PDMS mold. Then, the orthogonally microwrinkle patterns are generated inside the half-circular microchannel by a strain responsive wrinkling method. During the UV treatment on a PDMS substrate with uniaxial 40% stretch and a subsequent strain releasing step, the microwrinkle patterns perpendicular to the axial direction of the circular microchannel are generated, which can guide the circumferential alignment of HASMCs during cultivation. The analysis of orientation angle, shape index, and contractile protein marker expression indicates that the cultured HASMCs reveal the in vivo-like cell phenotype. Finally, a fully circular microchannel is produced by bonding two half-circular microchannels, and the HASMCs are cultured circumferentially inside the channels with high alignment and viability for 5 days. These results demonstrated the creation of an in vivo-like 3D smooth muscle cell layer in the circular microfluidic channel which can provide a bioassay platforms for in-depth study of HASMC biology and vascular function.

  4. Circumferential phased array of shear-horizontal wave magnetostrictive patch transducers for pipe inspection.

    PubMed

    Kim, Hoe Woong; Lee, Joo Kyung; Kim, Yoon Young

    2013-02-01

    Several investigations report effective uses of magnetostrictive patch transducers to generate and measure longitudinal and torsional guided waves in a pipe. They can be used to form a phased array for the circumferential inspection of pipes. Although there are circumferential phased arrays employing piezoelectric transducers or EMAT's, no magnetostrictive patch transducer based array system has been attempted. In this investigation, we aim to develop a circumferential phased magnetostrictive patch transducer (PMPT) array that can focus shear-horizontal waves at any target point on a cylindrical surface of a pipe. For the development, a specific configuration of a PMPT array employing six magnetostrictive patch transducers is proposed. A wave simulation model is also developed to determine time delays and amplitudes of signals generated by the transducers of the array. This model should be able to predict accurately the angular profiles of shear-horizontal waves generated by the transducers. For wave focusing, the time reversal idea will be utilized. The wave focusing ability of the developed PMPT array is tested with multiple-crack detection experiments. Imaging of localized surface inspection regions is also attempted by using wave signals measured by the developed PMPT array system.

  5. Wide local excision for Buschke-Löwenstein tumor or circumferential carcinoma in situ.

    PubMed

    Abbas, Maher A

    2011-09-01

    This study aimed to evaluate the outcome of patients with Buschke-Löwenstein tumor or circumferential anal carcinoma in situ who underwent wide local excision with flap or skin graft coverage of the wound. A retrospective review was conducted of all patients operated at Kaiser Permanente Los Angeles Medical Center during a 6-year period. Outcome measures included postoperative complications, functional results, recurrence rate, and re-intervention rate. Of 152 patients operated for dysplastic anal lesions or tumors, 10 (7%) underwent wide local excision for Buschke-Löwenstein tumor or circumferential anal carcinoma in situ [men 70%, mean age 36 years]. Median duration of symptoms was 5 years. Eighty percent of patients had prior operations and 50% were positive for the human immunodeficiency virus. Mean size of the lesion was 41 cm(2). Microscopic margin positivity was noted in 60%. Wound was closed with house advancement flap in majority of patients. Only one patient had fecal diversion. Median length of stay was 2 days. Postoperative complications were noted in 50% of patients. Rate of transient postoperative incontinence was 30%. Recurrent disease was noted in 3 patients with the human immunodeficiency virus [median follow-up: 18 months]. All recurrences were treated with local fulguration or medication. Wide local excision with flap or skin graft coverage is an option for patients with Buschke-Löwenstein tumor or circumferential anal carcinoma in situ. Close postoperative surveillance is advised due to the risk of recurrent disease, especially in patients with the human immunodeficiency virus.

  6. Nonlinear Bulging Factors for Longitudinal and Circumferential Cracks in Cylindrical Shells Subjected to Combined Loads

    NASA Technical Reports Server (NTRS)

    Young, Richard D.; Rose, Cheryl A.; Starnes, James H., Jr.

    2000-01-01

    Results of a geometrically nonlinear finite element parametric study to determine curvature correction factors or bulging factors that account for increased crack-tip stresses due to curvature for longitudinal and circumferential cracks in unstiffened cylindrical shells subjected to combined loads are presented. Nondimensional parameters varied in the study include the shell curvature parameter, l , which is a function of the shell radius, the shell wall thickness, and the crack length; a pressure loading parameter, h , which is a function of the shell geometry, material properties and the applied internal pressure; and a biaxial loading parameter, c , which is the ratio of the farfield axial stress to the farfield circumferential stress. The major results are presented in the form of contour plots of the bulging factor as a function of these three nondimensional parameters. These plots identify the ranges of the shell curvature and loading parameters for which the effects of geometric nonlinearity are significant, and show the effect of the biaxial loads on the value of the bulging factor. Simple empirical expressions for the bulging factor are then derived from the numerical results and are shown to predict accurately the nonlinear response of shells with longitudinal and circumferential cracks.

  7. A novel in vitro model for microvasculature reveals regulation of circumferential ECM organization by curvature.

    PubMed

    Barreto-Ortiz, Sebastian F; Zhang, Shuming; Davenport, Matthew; Fradkin, Jamie; Ginn, Brian; Mao, Hai-Quan; Gerecht, Sharon

    2013-01-01

    In microvascular vessels, endothelial cells are aligned longitudinally whereas several components of the extracellular matrix (ECM) are organized circumferentially. While current three-dimensional (3D) in vitro models for microvasculature have allowed the study of ECM-regulated tubulogenesis, they have limited control over topographical cues presented by the ECM and impart a barrier for the high-resolution and dynamic study of multicellular and extracellular organization. Here we exploit a 3D fibrin microfiber scaffold to develop a novel in vitro model of the microvasculature that recapitulates endothelial alignment and ECM deposition in a setting that also allows the sequential co-culture of mural cells. We show that the microfibers' nanotopography induces longitudinal adhesion and alignment of endothelial colony-forming cells (ECFCs), and that these deposit circumferentially organized ECM. We found that ECM wrapping on the microfibers is independent of ECFCs' actin and microtubule organization, but it is dependent on the curvature of the microfiber. Microfibers with smaller diameters (100-400 µm) guided circumferential ECM deposition, whereas microfibers with larger diameters (450 µm) failed to support wrapping ECM. Finally, we demonstrate that vascular smooth muscle cells attached on ECFC-seeded microfibers, depositing collagen I and elastin. Collectively, we establish a novel in vitro model for the sequential control and study of microvasculature development and reveal the unprecedented role of the endothelium in organized ECM deposition regulated by the microfiber curvature.

  8. Lumbar extracavitary corpectomy with a single stage circumferential arthrodesis: surgical technique and clinical series.

    PubMed

    Singh, Kern; Park, Daniel K

    2012-07-01

    Circumferential arthrodesis and reconstruction is necessary after a lumbar corpectomy in the setting of malignancy and infection. The advent of expandable cage technology now allows for safe anterior column reconstruction via a posterior approach with no transection and minimal retraction of the lumbar spinal nerve roots. Fifteen patients underwent a single-stage, circumferential corpectomy and anterior spinal reconstruction with an expandable cage via a midline, posterior, lateral lumbar extracavitary approach. Posterior segmental pedicle screw fixation and iliac crest bone graft was used in all cases. Fifteen lumbar extracavitary corpectomy nerve root-sparing procedures have been performed to date, with at least 1-year follow-up (12 tumors/3 infections). No patient suffered any neurological complications. One patient suffered from a postoperative myocardial infarction 10 days after the procedure. Two patients had medical complications that were treated without sequelae. We present a technical description and case series of patients undergoing a single-stage, circumferential corpectomy and anterior spinal reconstruction with an expandable cage via a midline, posterior, lateral lumbar extracavitary approach with at least 1-year follow-up. The technique is safe, technically feasible, and obviates an anterior approach in this oftentimes critically ill patient population.

  9. Nonlinear vibrations and energy exchange of single-walled carbon nanotubes. Circumferential flexural modes

    NASA Astrophysics Data System (ADS)

    Strozzi, Matteo; Smirnov, Valeri V.; Manevitch, Leonid I.; Milani, Massimo; Pellicano, Francesco

    2016-10-01

    In this paper, the nonlinear vibrations and energy exchange of single-walled carbon nanotubes (SWNTs) are studied. The Sanders-Koiter theory is applied to model the nonlinear dynamics of the system in the case of finite amplitude of vibration. The SWNT deformation is described in terms of longitudinal, circumferential and radial displacement fields. Simply supported, clamped and free boundary conditions are considered. The circumferential flexural modes (CFMs) are investigated. Two different approaches based on numerical and analytical models are compared. In the numerical model, an energy method based on the Lagrange equations is used to reduce the nonlinear partial differential equations of motion to a set of nonlinear ordinary differential equations, which is solved by using the implicit Runge-Kutta numerical method. In the analytical model, a reduced form of the Sanders-Koiter theory assuming small circumferential and tangential shear deformations is used to get the nonlinear ordinary differential equations of motion, which are solved by using the multiple scales analytical method. The transition from energy beating to energy localization in the nonlinear field is studied. The effect of the aspect ratio on the analytical and numerical values of the nonlinear energy localization threshold for different boundary conditions is investigated. Time evolution of the total energy distribution along the axis of a simply supported SWNT

  10. Laminar mixed convection in horizontal concentric annuli with non-uniform circumferential heating

    NASA Astrophysics Data System (ADS)

    Habib, M. A.; Negm, A. A. A.

    Steady, laminar, mixed convection in the fully developed region of horizontal concentric annuli has been investigated numerically for the case of non-uniform circumferential heating. Two heating conditions were studied, one in which a 180∘ arc encompassing the top half of inner surface of the inner cylinder is uniformly heated while the bottom half is kept insulated, and the other in which the heated and the insulated surfaces were reversed. The fluid flow and heat transfer characteristics were found to be affected by the heating conditions. For the investigated range of the governing buoyancy parameter, the modified Grashof number (Gr*), it was found that bottom heating arrangement gives rise to a vigorous secondary flow, with the result that the average Nusselt numbers are much higher than those for pure forced convection. On the other hand, the local Nusselt numbers are nearly circumferentially uniform. In the case of top heating arrangement, a less vigorous secondary flow is induced because of temperature stratification, with average Nusselt numbers that are substantially lower than those for bottom heating and with large circumferential variation of the local Nusselt number.

  11. Prediction of axis shift distortion during circumferential welding of thin pipes using the finite element method

    SciTech Connect

    Ravichandran, G.; Raghupathy, V.P.; Ganesan, N.; Krishnakumar, R.

    1997-01-01

    Axis shift distortion is one type of distortion encountered during the circumferential welding of large, thin pipes. the result of this is the loss of coaxiality of the pipes. This type of distortion is caused by the time lag in the solidification of various segments of weld metal around the circumference. The development of shrinkage forces in the weld metal especially in the axial direction is nonuniform due to the time lag, and this causes axis shift for the pipes. the development of a mathematical model using the finite element method for prediction of axis shift distortion in thin pipes is described in this work. Thermal analysis and subsequent elastic-plastic stress analysis for the pipe are performed using four-noded, bilinear degenerated shell elements. In addition to axis shift distortion, axial and circumferential stress distributions in the pipe are also determined by the model. The model is validated by conducting partial welding on the circumference of a thin pipe and measuring the transient thermal history and root opening at the bottom. Details of thermal and elastic-plastic analyses, welding trials, thermal and displacement results and axial and circumferential stress results are presented in this paper.

  12. Circumferential silicone sponge scleral buckling induced axial length changes: case series and comparison to literature.

    PubMed

    Ophir, Shira Sheen; Friehmann, Asaf; Rubowitz, Alexander

    2017-01-01

    This study compared axial length changes induced by circumferential scleral buckling using a silicone sponge with literature reports for solid silicone rubber. Records of patients treated with scleral buckling in 2009-2013 using a silicone sponge, with preoperative axial length biometry measurements were reviewed. Additional information included age, type of surgery, additional surgeries, phakic status and anatomical success of reattachment. Patients underwent repeat biometry. The medical literature was reviewed for articles describing axial length changes induced by circumferential buckling using solid silicone rubber. Twenty-eight patients (mean age 49.7 years, range 16-72) met the inclusion criteria. Mean axial length was 25.38 mm preoperatively and 26.12 mm at least 6 months postoperatively (SD 0.50 ± 0.09, p < 0.001); a mean increase of 0.74 mm. Half the patients subsequently underwent cataract surgery. Post-operative changes were not significant compared to pre-surgical refraction and corneal astigmatism. Axial length change was not significant between sexes (9 women and 19 men). Axial length changes induced by circumferential scleral buckling using silicone sponge exclusively are similar to those reported in the literature for solid silicone rubber buckles. Scleral buckling using a silicone sponge, which may offer several surgical advantages, induces an acceptable axial length change similar to that seen with widely-used solid silicone rubber buckles.

  13. How Infants Encode Spatial Extent

    ERIC Educational Resources Information Center

    Duffy, Sean; Huttenlocher, Janellen; Levine, Susan; Duffy, Renee

    2005-01-01

    This study explores how infants encode an object's spatial extent. We habituated 6.5-month-old infants to a dowel inside a container and then tested whether they dishabituate to a change in absolute size when the relation between dowel and container is held constant (by altering the size of both container and dowel) and when the relation changes…

  14. On guided circumferential waves in soft electroactive tubes under radially inhomogeneous biasing fields

    NASA Astrophysics Data System (ADS)

    Wu, Bin; Su, Yipin; Chen, Weiqiu; Zhang, Chuanzeng

    2017-02-01

    Soft electroactive (EA) tube actuators and many other cylindrical devices have been proposed recently in literature, which show great advantages over those made from conventional hard solid materials. However, their practical applications may be limited because these soft EA devices are prone to various failure modes. In this paper, we present an analysis of the guided circumferential elastic waves in soft EA tube actuators, which has potential applications in the in-situ nondestructive evaluation (NDE) or online structural health monitoring (SHM) to detect structural defects or fatigue cracks in soft EA tube actuators and in the self-sensing of soft EA tube actuators based on the concept of guided circumferential elastic waves. Both circumferential SH and Lamb-type waves in an incompressible soft EA cylindrical tube under inhomogeneous biasing fields are considered. The biasing fields, induced by the application of an electric voltage difference to the electrodes on the inner and outer cylindrical surfaces of the EA tube in addition to an axial pre-stretch, are inhomogeneous in the radial direction. Dorfmann and Ogden's theory of nonlinear electroelasticity and the associated linear theory for small incremental motion constitute the basis of our analysis. By means of the state-space formalism for the incremental wave motion along with the approximate laminate technique, dispersion relations are derived in a particularly efficient way. For a neo-Hookean ideal dielectric model, the proposed approach is first validated numerically. Numerical examples are then given to show that the guided circumferential wave propagation characteristics are significantly affected by the inhomogeneous biasing fields and the geometrical parameters. Some particular phenomena such as the frequency veering and the nonlinear dependence of the phase velocity on the radial electric voltage are discussed. Our numerical findings demonstrate that it is feasible to use guided circumferential

  15. Influence of the circumferential speed of a resin bond grinding wheel on the properties of a ground aspheric surface

    NASA Astrophysics Data System (ADS)

    Matousek, Ondrej; Tomka, David; Prochaska, Frantisek; Polak, Jaroslav

    2015-01-01

    In recent times, resin bond grinding wheels have often been used for the precise grinding of aspheric surfaces. In this paper, the influence of changes in the circumferential speed of the resin bond grinding wheel on the microroughness of the produced surface and also on the volume of the structures and the scratches is presented. The article also discusses how the cutting wear of the tool affects the surface quality and shows the correlation between the circumferential speed and the rate of degradation of the resin bond grinding wheel. A circumferential speed interval from 12 m/s to 24 m/s was investigated and the effect of tool degradation was observed at 1.9-hour intervals. The results of the experiment show that the optimal circumferential speed of the tool lies around 20 m/s. At this speed, the tool produces a perfectly polishable surface and tool degradation is minimized.

  16. Scalp ulceration from a circumferential head dressing after craniotomy: Case report of an uncommon complication due to human error.

    PubMed

    Singhal, Ashutosh; Bray, Peter W; Bernstein, Mark

    2004-01-01

    The present paper describes a previously unpublished complication of the application of a circumferential head dressing after cranial neuro-surgery. A 34-year-old woman developed a large area of skin necrosis on her forehead from a circumferential head dressing applied after the surgical removal of a colloid cyst. Neurological recovery was excellent but plastic surgical repair of her iatrogenic cosmetic injury was required.

  17. Analytical approach to calculate bending, longitudinal and torsional local stiffness of an asymmetric circumferential crack with contact condition

    NASA Astrophysics Data System (ADS)

    Sharafi, Mojtaba Meidan; Nikravesh, Majid Yadavar; Safarpour, Pedram

    2017-09-01

    In this paper, bending, longitudinal and torsional stiffness of an eccentric circumferential crack is investigated with taking into account contact condition on the crack surfaces based on fracture mechanics. Although several researches have analyzed stress intensity factors of symmetric circumferential crack, the stiffness of an asymmetric circumferential crack in different directions (along and perpendicular to eccentricity) regarding contact condition has not been studied by an analytical method until now. In this paper we aim to describe behavior of eccentric circumferential crack under axial loading and establish a relation between axial force and the resulting displacement vector. The twisting angle of asymmetric circumferential crack due to torsional loading is also calculated and compared to twisting angle of a symmetric crack. In order to simulate the local bending stiffness in the contact condition, nonlinear governing equations of bending stiffness associated to cracked beam section is developed by dividing it to strip elements and utilizing stiffness equations related to noncontact condition. It is validated by 3D finite element (FE) nonlinear model. Results show a significant compatibility between presented analytical and 3D FE methods. Moreover results of simulations show that without taking into account contact condition, axial, torsional and bending stiffness of symmetric and asymmetric circumferential crack are equal and radius of un-cracked area is the only influential factor.

  18. Endocardial endothelium in the avascular frog heart: role for diffusion of NO in control of cardiac O2 consumption.

    PubMed

    Adler, Alexandra; Huang, Harer; Wang, Zipping; Conetta, Joseph; Levee, Ellen; Zhang, Xiaoping; Hintze, Thomas H

    2004-07-01

    We investigated the role of nitric oxide (NO) in the control of myocardial O(2) consumption in the hearts of female Xenopus frogs, which lack a coronary vascular endothelium and in which the endocardial endothelium is the only source of NO to regulate cardiac myocyte function. Hence, frogs are an ideal model in which to explore the role of diffusion of NO from the endocardial endothelium (EE) without vascular endothelial or cardiac cell NO production. In Xenopus hearts we examined the regulation of cardiac O(2) consumption in vitro at 25 degrees C and 37 degrees C. The NO-mediated control of O(2) consumption by bradykinin or carbachol was significantly (P < 0.05) lower at 25 degrees C (79 +/- 13 or 73 +/- 11 nmol/min) than at 37 degrees C (159 +/- 26 or 201 +/- 13 nmol/min). The response to the NO donor S-nitroso-N-acetyl penicillamine was also markedly lower at 25 degrees C (90 +/- 8 nmol/min) compared with 37 degrees C (218 +/- 15 nmol/min). When Triton X-100 was perfused into hearts, the inhibition of myocardial O(2) consumption by bradykinin (18 +/- 2 nmol/min) or carbachol (29 +/- 4 nmol/min) was abolished. Hematoxylin and eosin slides of Triton X-100-perfused heart tissue confirmed the absence of the EE. Although endothelial NO synthase protein levels were decreased to a variable degree in the Triton X-100-perfused heart, NO(2) production (indicating eNOS activity) decreased by >80%. It appears that the EE of the frog heart is the sole source of NO to regulate myocyte O(2) consumption. When these cells are removed, the ability of NO to regulate O(2) consumption is severely limited. Thus our results suggest that the EE produces enough NO, which diffuses from the EE to cardiac myocytes, to regulate myocardial O(2) consumption. Because of the close proximity of the EE to underlying myocytes, NO can diffuse over a distance and act as a messenger between the EE and the rest of the heart to control mitochondrial function and O(2) consumption.

  19. High-resolution endocardial and epicardial optical mapping in a sheep model of stretch-induced atrial fibrillation.

    PubMed

    Filgueiras-Rama, David; Martins, Raphael Pedro; Ennis, Steven R; Mironov, Sergey; Jiang, Jiang; Yamazaki, Masatoshi; Kalifa, Jérôme; Jalife, Josè; Berenfeld, Omer

    2011-07-29

    Atrial fibrillation (AF) is a complex cardiac arrhythmia with high morbidity and mortality.(1,2) It is the most common sustained cardiac rhythm disturbance seen in clinical practice and its prevalence is expected to increase in the coming years.(3) Increased intra-atrial pressure and dilatation have been long recognized to lead to AF,(1,4) which highlights the relevance of using animal models and stretch to study AF dynamics. Understanding the mechanisms underlying AF requires visualization of the cardiac electrical waves with high spatial and temporal resolution. While high-temporal resolution can be achieved by conventional electrical mapping traditionally used in human electrophysiological studies, the small number of intra-atrial electrodes that can be used simultaneously limits the spatial resolution and precludes any detailed tracking of the electrical waves during the arrhythmia. The introduction of optical mapping in the early 90's enabled wide-field characterization of fibrillatory activity together with sub-millimeter spatial resolution in animal models(5,6) and led to the identification of rapidly spinning electrical wave patterns (rotors) as the sources of the fibrillatory activity that may occur in the ventricles or the atria.(7-9) Using combined time- and frequency-domain analyses of optical mapping it is possible to demonstrate discrete sites of high frequency periodic activity during AF, along with frequency gradients between left and right atrium. The region with fastest rotors activates at the highest frequency and drives the overall arrhythmia.(10,11) The waves emanating from such rotor interact with either functional or anatomic obstacles in their path, resulting in the phenomenon of fibrillatory conduction.(12) Mapping the endocardial surface of the posterior left atrium (PLA) allows the tracking of AF wave dynamics in the region with the highest rotor frequency. Importantly, the PLA is the region where intracavitary catheter-based ablative

  20. Prophylactic catheter ablation of ventricular tachycardia before cardioverter-defibrillator implantation in patients with non-ischemic cardiomyopathy: Clinical outcomes after a single endocardial ablation.

    PubMed

    Suzuki, Atsushi; Yoshida, Akihiro; Takei, Asumi; Fukuzawa, Koji; Kiuchi, Kunihiko; Takami, Kaoru; Itoh, Mitsuaki; Imamura, Kimitake; Fujiwara, Ryudo; Nakanishi, Tomoyuki; Yamashita, Soichiro; Matsumoto, Akinori; Shimane, Akira; Okajima, Katsunori; Hirata, Ken-Ichi

    2015-06-01

    Outcomes related to prophylactic catheter ablation (PCA) for ventricular tachycardia (VT) before implantable cardioverter-defibrillator (ICD) implantation in non-ischemic cardiomyopathy (NICM) are not well characterized. We assessed the efficacy of single endocardial PCA in NICM patients. We retrospectively analyzed 101 consecutive NICM patients with sustained VT. We compared clinical outcomes of patients who underwent PCA (ABL group) with those who did not (No ABL group). Successful PCA was defined as no inducible clinical VT. We also compared the clinical outcomes of patients with successful PCA (PCA success group) with those of the No ABL group. Endpoints were appropriate ICD therapy (shock and anti-tachycardia pacing) and the occurrence of electrical storm (ES). PCA was performed in 42 patients, and it succeeded in 20. The time to ES occurrence was significantly longer in the ABL group than in the No ABL group (p=0.04). The time to first appropriate ICD therapy and ES occurrence were significantly longer in the PCA success group than in the No ABL group (p=0.02 and p<0.01, respectively). Single endocardial PCA can decrease ES occurrence in NICM patients. However, high rates of VT recurrence and low success rates are issues to be resolved; therefore, the efficacy of single endocardial PCA is currently limited.

  1. Prophylactic catheter ablation of ventricular tachycardia before cardioverter-defibrillator implantation in patients with non-ischemic cardiomyopathy: Clinical outcomes after a single endocardial ablation

    PubMed Central

    Suzuki, Atsushi; Yoshida, Akihiro; Takei, Asumi; Fukuzawa, Koji; Kiuchi, Kunihiko; Takami, Kaoru; Itoh, Mitsuaki; Imamura, Kimitake; Fujiwara, Ryudo; Nakanishi, Tomoyuki; Yamashita, Soichiro; Matsumoto, Akinori; Shimane, Akira; Okajima, Katsunori; Hirata, Ken-ichi

    2015-01-01

    Background Outcomes related to prophylactic catheter ablation (PCA) for ventricular tachycardia (VT) before implantable cardioverter-defibrillator (ICD) implantation in non-ischemic cardiomyopathy (NICM) are not well characterized. We assessed the efficacy of single endocardial PCA in NICM patients. Methods We retrospectively analyzed 101 consecutive NICM patients with sustained VT. We compared clinical outcomes of patients who underwent PCA (ABL group) with those who did not (No ABL group). Successful PCA was defined as no inducible clinical VT. We also compared the clinical outcomes of patients with successful PCA (PCA success group) with those of the No ABL group. Endpoints were appropriate ICD therapy (shock and anti-tachycardia pacing) and the occurrence of electrical storm (ES). Results PCA was performed in 42 patients, and it succeeded in 20. The time to ES occurrence was significantly longer in the ABL group than in the No ABL group (p=0.04). The time to first appropriate ICD therapy and ES occurrence were significantly longer in the PCA success group than in the No ABL group (p=0.02 and p<0.01, respectively). Conclusion Single endocardial PCA can decrease ES occurrence in NICM patients. However, high rates of VT recurrence and low success rates are issues to be resolved; therefore, the efficacy of single endocardial PCA is currently limited. PMID:26336545

  2. Posterior-Only Circumferential Decompression and Reconstruction in the Surgical Management of Lumbar Vertebral Osteomyelitis.

    PubMed

    Skovrlj, Branko; Guzman, Javier Z; Caridi, John; Cho, Samuel K

    2016-02-01

    Study Design Case report. Objective The purpose of this report is to discuss the surgical management of lumbar vertebral osteomyelitis with a spinal epidural abscess (SEA) and present a single-stage, posterior-only circumferential decompression and reconstruction with instrumentation using an expandable titanium cage and without segmental nerve root sacrifice as an option in the treatment of this disease process. Methods We report a 42-year-old man who presented with 3 days of low back pain and chills who rapidly decompensated with severe sepsis following admission. Magnetic resonance imaging of his lumbosacral spine revealed intramuscular abscesses of the left paraspinal musculature and iliopsoas with SEA and L4 vertebral body involvement. The patient failed maximal medical treatment, which necessitated surgical treatment as a last resort for infectious source control. He underwent a previously undescribed procedure in the setting of SEA: a single-stage, posterior-only approach for circumferential decompression and reconstruction of the L4 vertebral body with posterior segmental instrumented fixation. Results After the surgery, the patient's condition gradually improved; however, he suffered a wound dehiscence necessitating a surgical exploration and deep wound debridement. Six months after the surgery, the patient underwent a revision surgery for adjacent-level pseudarthrosis. At 1-year follow-up, the patient was pain-free and off narcotic pain medication and had returned to full activity. Conclusion This patient is the first reported case of lumbar osteomyelitis with SEA treated surgically with a single-stage, posterior-only circumferential decompression and reconstruction with posterior instrumentation. Although this approach is more technically challenging, it presents another viable option for the treatment of lumbar vertebral osteomyelitis that may reduce the morbidity associated with an anterior approach.

  3. Posterior-Only Circumferential Decompression and Reconstruction in the Surgical Management of Lumbar Vertebral Osteomyelitis

    PubMed Central

    Skovrlj, Branko; Guzman, Javier Z.; Caridi, John; Cho, Samuel K.

    2015-01-01

    Study Design Case report. Objective The purpose of this report is to discuss the surgical management of lumbar vertebral osteomyelitis with a spinal epidural abscess (SEA) and present a single-stage, posterior-only circumferential decompression and reconstruction with instrumentation using an expandable titanium cage and without segmental nerve root sacrifice as an option in the treatment of this disease process. Methods We report a 42-year-old man who presented with 3 days of low back pain and chills who rapidly decompensated with severe sepsis following admission. Magnetic resonance imaging of his lumbosacral spine revealed intramuscular abscesses of the left paraspinal musculature and iliopsoas with SEA and L4 vertebral body involvement. The patient failed maximal medical treatment, which necessitated surgical treatment as a last resort for infectious source control. He underwent a previously undescribed procedure in the setting of SEA: a single-stage, posterior-only approach for circumferential decompression and reconstruction of the L4 vertebral body with posterior segmental instrumented fixation. Results After the surgery, the patient's condition gradually improved; however, he suffered a wound dehiscence necessitating a surgical exploration and deep wound debridement. Six months after the surgery, the patient underwent a revision surgery for adjacent-level pseudarthrosis. At 1-year follow-up, the patient was pain-free and off narcotic pain medication and had returned to full activity. Conclusion This patient is the first reported case of lumbar osteomyelitis with SEA treated surgically with a single-stage, posterior-only circumferential decompression and reconstruction with posterior instrumentation. Although this approach is more technically challenging, it presents another viable option for the treatment of lumbar vertebral osteomyelitis that may reduce the morbidity associated with an anterior approach. PMID:26835214

  4. Generalized thermoelastic wave propagation in circumferential direction of transversely isotropic cylindrical curved plates

    NASA Astrophysics Data System (ADS)

    Sharma, J. N.; Pathania, Vijayata

    2005-03-01

    The propagation of thermoelastic waves along circumferential direction in homogeneous, transversely isotropic, cylindrical curved plates has been investigated in the context of theories of thermoelasticity. This type of study is important for ultrasonic non-destructive inspection of large-diameter pipes, which helps in the health monitoring of ailing infrastructure. Longitudinal stress-corrosion cracks are usually temperature dependent and can be detected more efficiently by inducing circumferential waves; hence the study of generalized thermoelastic wave propagation in the circumferential direction in a pipe wall is essential. Mathematical modeling of the problem of obtaining dispersion curves for curved transversely isotropic thermally conducting elastic plates leads to coupled differential equations. The model has been simplified by using the Helmholtz decomposition technique and the resulting equations have been solved by using separation of variable method to obtain the secular equations in isolated mathematical conditions for the plates with stress-free or rigidly fixed, thermally insulated and isothermal boundary surfaces. The closed form solutions are also obtained under different situations and conditions. The longitudinal shear motion and axially symmetric shear vibration modes get decoupled from the rest of the motion and are not affected by thermal variations, whereas for the non-axially symmetric case of plane strain vibrations, these modes remain coupled and are affected by temperature changes. Moreover, these vibration modes are found to be dispersive and dissipative in character. In order to illustrate theoretical development, numerical solutions are obtained and presented graphically for a zinc plate. The obtained results are also compared with those available in the literature in case of waves in cylindrical shell/circular annulus in the absence of thermomechanical coupling and thermal relaxation times.

  5. Electrostatic MEMS resonating micro-polygonal scanner for circumferential endoscopic bio-imaging

    NASA Astrophysics Data System (ADS)

    Mu, Xiaojing; Zhou, Guangya; Yu, Hongbin; Tsai, Julius Ming-Lin; Neo, Wee Keong; Kumar, A. Senthil; Chau, Fook Siong

    2013-03-01

    An electrostatically-driven microelectromechanical systems (MEMS) based pyramidal-polygonal micro-scanner is developed for circumferential-scanning endoscopic probes. In this paper, an endoscopic optical coherence tomography (OCT) probe is proposed, which utilizes multiple parallel incident light beams to drastically reduce the required mechanical rotation angle to achieve near 360-degree circumferential scanning. Manual assembly is employed to construct this micro scanner, which combines a silicon micromachined MEMS actuator with four sets of electrostatic comb-drives and a polymer-based pyramidal-polygonal micro-reflector. The pyramidal-polygonal micro-reflector is developed using a combination of high-precision diamond turning and soft lithography molding technologies. The measured average surface roughness and root-mean-square roughness of the diamond turned mold are 7.02 nm and 9.02 nm respectively, and those of the PDMS casted polygon micro-reflector with an Au coating are 48.95 nm and 61.90 nm respectively. Since near-infrared light sources with wavelengths ranging from 930 nm to 1550 nm are typically utilized for OCT applications, the surface roughness of the polygon reflector is better than λ/10 of the operating wavelength indicating that its quality meets the requirement of the OCT bio-imaging applications. An overall optical scan angle of near-360 degrees is demonstrated experimentally at a resonant frequency of 180 Hz with 80 Vpp ac driving voltage. The proposed MEMS scanner offers an alternative solution for circumferential scanning in endoscopic OCT probes owing to its advantages of compact design, fast scanning speed and low operational power consumption.

  6. Single stage circumferential lingual mucosal graft urethroplasty in near obliterative bulbar urethra stricture: A novel technique

    PubMed Central

    Sharma, Umesh; Yadav, Sher Singh; Tomar, Vinay; Garg, Amit

    2016-01-01

    Aims: This is a prospective study of the use and efficacy of a novel technique of circumferential tubularised lingual mucosal graft (LMG) in obliterative and near obliterative bulbar urethral stricture of >2 cm where excisional and augmented anastomotic urethroplasty are not feasible. Materials and Methods: The stenotic urethral segment was opened dorsally in midline and fibrosed urethra was excised taking care to preserve the healthy spongiosum tissue. LMG (av. Length 3 cm) was placed from one end of corporal body towards spongy tissue in a circumferential manner. Another LMG was placed in similar manner to deal with longer stricture. The urethra was tubularised over 14 Fr silicone catheter. Results: A total of 12 men, of mean age 47 years underwent this procedure. The mean follow up period was 11 months starting from July 2014 till manuscript submission. Follow up included voiding cystourethrogram at 3 weeks, cystoscopy at 3 months (one patient didn’t turned up) and subsequent follow up. Mean stricture length was 4.66 cm (range, 3–8.5 cm) and mean operative time was 195 min. (range, 160 to 200 min.). The technique was successful (normal voiding with no need for any post-operative procedure) in 11(91.6%) patients. One patient developed early recurrence at 4 month of surgery and had anastomotic stricture which was successfully managed by direct visual internal urethrotomy. Conclusion: Single stage circumferential tubularised graft urethroplasty is an excellent technique for strictures that include segments of obliterative and near obliterative diseased urethra. It provide a wider neourethra than patch graft urethroplasty. PMID:27141182

  7. Experimental study of flow distribution and pressure loss with circumferential inlet and outlet manifolds

    NASA Technical Reports Server (NTRS)

    Dittrich, R. T.

    1972-01-01

    Water flow tests with circumferential inlet and outlet manifolds were conducted to determine factors affecting fluid distribution and pressure losses. Various orifice sizes and manifold geometries were tested over a range of flow velocities. With inlet manifolds, flow distribution was related directly to orifice discharge coefficients. A correlation indicated that nonuniform distribution resulted when the velocity head ratio at the orifice was not in the range of constant discharge coefficient. With outlet manifolds, nonuniform flow was related to static pressure variations along the manifold. Outlet manifolds had appreciably greater pressure losses than comparable inlet manifolds.

  8. Aspects of circumferential waves in determining buckling capacity of cylindrical shells

    SciTech Connect

    Xu, J.; Bandyopadhyay, K.K.

    1996-12-01

    In an effort to quantify the failure behavior of a cylindrical shell when geometric imperfections are present and is subjected to a combination of axial load and internal pressure, the authors have carried out a series of analyses to investigate the effects of various load combinations and material behavior on the shell`s buckling capacity. To complete the characterization of buckling behavior of cylindrical shells, an evaluation was performed to examine the deformation modes in terms of circumferential waves in relation to the shell`s buckling capacity. This paper presents the results of the investigation.

  9. Limit pressure of a circumferentially reinforced SiC/Ti ring

    NASA Technical Reports Server (NTRS)

    Robinson, D. N.; Pastor, M. S.

    1991-01-01

    Limit loads under plane stress and plane strain are found for a circumferentially reinforced elastoplastic ring subjected to interior pressure. These are used as bounds on an estimate of the failure pressure of a SiC/Ti test rig that is being fabricated and tested. The ring is to serve as a benchmark against which deformation and failure analysis methods can be assessed. An anisotropic perfect plasticity idealization of the SiC/Ti ring material is made and used in the limit load calculations. An estimate of the failure pressure of the NASA/PW benchmark test ring is given.

  10. Investigations on an axial flow fan stage subjected to circumferential inlet flow distortion and swirl

    NASA Astrophysics Data System (ADS)

    Govardhan, M.; Viswanath, K.

    1997-12-01

    The combined effects of swirl and circumferential inlet flow distortion on the flow field of an axial flow fan stage are reported in this paper. The study involves measurements at the inlet of the rotor and exit of the rotor and stator at design and off design flow conditions. The study indicated that at the design flow condition, swirl had caused deterioration of the performance in addition to that caused by distortion. Pressure rise imparted in the distortion zone is higher than in the free zone. The attenuation of distortion is high in the presence of swirl.

  11. Growth behavior of surface cracks in the circumferential plane of solid and hollow cylinders

    NASA Technical Reports Server (NTRS)

    Forman, R. G.; Shivakumar, V.

    1986-01-01

    Experiments were conducted to study the growth behavior of surface fatigue cracks in the circumferential plane of solid and hollow cylinders. In the solid cylinders, the fatigue cracks were found to have a circular arc crack front with specific upper and lower limits to the arc radius. In the hollow cylinders, the fatigue cracks were found to agree accurately with the shape of a transformed semiellipse. A modification to the usual nondimensionalization expression used for surface flaws in flat plates was found to give correct trends for the hollow cylinder problem.

  12. Effect of rotor meridional velocity ratio on response to inlet radial and circumferential distortion

    NASA Technical Reports Server (NTRS)

    Sanger, N. L.

    1979-01-01

    Three single transonic fan stages, each having a different meridional velocity ratio across its rotor, were tested with two magnitudes of tip radial distortion and with a 90 deg circumferential distortion imposed on the inlet flow. The rotor with the lowest meridional velocity ratio (less than 0.9 at the tip) demonstrated the least degradation of performance due to these distortions. Loss and deviation angle data (as needed for performance prediction with radial distortion) calculated along actual streamlines for radially distorted flow and correlated against diffusion factor, showed consistent agreement with data calculated along design streamlines for undistorted flow.

  13. Improvement of charpy toughness of weld metal in circumferential SMAW of pipe

    SciTech Connect

    Abe, T.; Hara, N.; Sugino, T.; Naruse, S.; Kasai, N.

    1994-12-31

    Charpy toughness of weld metal made by low hydrogen and high cellulose electrodes for circumferential welding of API 5LX-60-X-70 grade of pipe is investigated. Improvements of charpy toughness was achieved by obtaining a fine microstructure through the adjustment of the quantity of alloying elements such as Mn and Ni and/or by the addition of an optimum range of micro-alloying elements like Ti and B for low hydrogen electrodes. It is reported that for high cellulose electrodes reducing the oxygen content in weld metal is also effective.

  14. Demonstration of TGF-β and XIIIα in Endocardial Biopsies of Carcinoid Heart Disease Patients: an Immunofluorescence Study

    PubMed Central

    Diepholz, Dorgrit; Wilke, Andreas; Maisch, Bernhard; Steverding, Dietmar

    2011-01-01

    Background Serotonin and other vasoactive substances play a critical role in the development of carcinoid heart disease, but the exact etiology of the illness is still unknown. Methods By using immunofluorescence microscopy, we investigated the expression of transforming growth factor-β (TGF-β) and the presence of fibrin-stabilizing factor (XIIIα) in endomyocardial biopsy specimens of patients with carcinoid heart disease. In addition, the tissue integrity of the specimens was studied by staining for laminin. Results Both TGF-β and XIIIα co-localized in the endocardium beneath carcinoid plaques: while TGF-β was found within myocytes, XIIIα was detected on the surface of cells in fibrotic lesions stretching out into the tissue. Laminin staining revealed that the integrity of the endocardium was dissolved and that the tissue consisted of hypertrophic and hypotrophic myocytes. Conclusions The results suggest that the presence of TGF-β and XIIIα in carcinoid heart lesions indicates that endocardial damage induced by serotonin and other vasoactive substances gives rise to an overshooting wound healing process.

  15. Early human experience with use of a deflectable fiberoptic endocardial visualization catheter to facilitate coronary sinus cannulation.

    PubMed

    Anh, D J; Chen, Henry A; Eversull, Christian S; Mourlas, Nicholas J; Mead, R Hardwin; Liem, L Bing; Hsia, Henry H; Wang, Paul J; Al-Ahmad, Amin

    2006-08-01

    Despite improvements in cardiac resynchronization therapy (CRT) implantation techniques, a significant minority of CRT attempts are unsuccessful. Inability to cannulate the coronary sinus (CS) because of difficult anatomy is a major reason for unsuccessful CRT implantation. Direct visualization of intracardiac structures during the implant may facilitate access into the CS. The present study describes CRT implantation with the aid of an endocardial visualization catheter (EVC). Fifty-eight consecutive patients (mean age 72 +/- 12 years; ejection fraction 26.2% +/- 7.0%; New York Heart Association [NYHA] class 2.9) underwent CRT implantation using a steerable fiberoptic EVC (Acumen Medical, Inc., Sunnyvale, CA). The EVC was able to visualize the CS ostium in all cases. The CS was successfully cannulated in 57 (98.3%) of 58 patients. The time from vascular access to CS visualization was 6 +/- 5 minutes, and the total time to CS access was 8 +/- 6 minutes. Successful left ventricle (LV) lead implantation was accomplished in 55 (94.8%) of 58 patients. Three patients who had a previous history of failed LV lead implantation were successfully implanted using the EVC. Fiberoptic imaging of intracardiac structures during CRT implantation may be performed rapidly in a wide range of patients with an EVC. The ability to visualize right atrial anatomy may aid CS access and LV lead implantation.

  16. Id4 functions downstream of Bmp signaling to restrict TCF function in endocardial cells during atrioventricular valve development.

    PubMed

    Ahuja, Suchit; Dogra, Deepika; Stainier, Didier Y R; Reischauer, Sven

    2016-04-01

    The atrioventricular canal (AVC) connects the atrial and ventricular chambers of the heart and its formation is critical for the development of the cardiac valves, chamber septation and formation of the cardiac conduction system. Consequently, problems in AVC formation can lead to congenital defects ranging from cardiac arrhythmia to incomplete cardiac septation. While our knowledge about early heart tube formation is relatively comprehensive, much remains to be investigated about the genes that regulate AVC formation. Here we identify a new role for the basic helix-loop-helix factor Id4 in zebrafish AVC valve development and function. id4 is first expressed in the AVC endocardium and later becomes more highly expressed in the atrial chamber. TALEN induced inactivation of id4 causes retrograde blood flow at the AV canal under heat induced stress conditions, indicating defects in AV valve function. At the molecular level, we found that id4 inactivation causes misexpression of several genes important for AVC and AV valve formation including bmp4 and spp1. We further show that id4 appears to control the number of endocardial cells that contribute to the AV valves by regulating Wnt signaling in the developing AVC endocardium. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Endocardial Remodeling in Heart Failure Patients with Impaired and Preserved Left Ventricular Systolic Function--A Magnetic Resonance Image Study.

    PubMed

    Lin, Lian-Yu; Su, Mao-Yuan M; Pham, Van-Truong; Tran, Thi-Thao; Wang, Yung-Hung; Tseng, Wen-Yih I; Lo, Men-Tzung; Lin, Jiunn-Lee

    2016-02-15

    Left ventricular (LV) trabeculation has been studied in certain forms of cardiomyopathy. However, the changes of LV endocardial trabeculation during the remodeling process leading to heart failure (HF) are unclear. Seventy-four patients with systolic heart failure (SHF), 65 with heart failure with preserved ejection fraction (HFpEF) and 61 without HF were prospectively enrolled. All subjects received magnetic resonance imaging (MRI) study including cine, T1 and late gadolinium enhancement (LGE) images. Trabecular-papillary muscle (TPM) mass, fractal dimension (FD) and extracellular volume (ECV) were derived. The results showed that TPM mass index was higher in patients with SHF than that in patients with HFpEF and non-HF. The TPM mass-LV mass ratio (TPMm/LVM) was higher in SHF group than that in HFpEF and non-HF. FD was not different among groups. The presence of LGE was inversely associated with TPM mass index and TPMm/LVM while the ECV were positively associated with TPMm/LVM. The FD was positively associated with LV chamber size. In conclusion, TPM increases in patients with SHF and are probably related to myocardial cell hypertrophy and fibrotic repair during remodeling. The FD increases with the dilatation of LV chamber but remain unchanged with the deterioration of LV function.

  18. Length-tension relationships of sub-epicardial and sub-endocardial single ventricular myocytes from rat and ferret hearts.

    PubMed

    Cazorla, O; Le Guennec, J Y; White, E

    2000-05-01

    In vivo the sub-epicardial myocardium (EPI) and sub-endocardial myocardium (ENDO) operate over different ranges of sarcomere length (SL). However, it has not been previously shown whether EPI and ENDO work upon different ranges of the same or differing length-tension curves. We have compared the SL-tension relationship of intact, single ventricular EPI and ENDO myocytes from rat and ferret hearts. Cells were attached to carbon fibres of known compliance in order to stretch them and to record force at rest (passive tension) and during contractions (active tension). In both species, ENDO cells were significantly stiffer (i.e. had steeper SL-passive tension relationships) than EPI cells. Ferret ENDO cells had significantly steeper SL-active tension relationships than EPI cells; rat cells tended to behave similarly but no significant regional differences in active properties were observed. There were no inter-species differences in the active and passive properties of EPI cells, but ferret ENDO cells displayed significantly steeper passive and active SL-tension relationships than rat ENDO. We conclude that in vivo, ferret EPI and ENDO myocytes will function over different ranges of different SL-tension curves. There is a close relationship between SL and active tension (the Frank-Starling law of the heart), and our observations suggest that regional differences in the response to ventricular dilation will depend on both the change in SL and differing regional slopes of the SL-active tension curves.

  19. Nuclear Membranes ETB Receptors Mediate ET-1-induced Increase of Nuclear Calcium in Human Left Ventricular Endocardial Endothelial Cells.

    PubMed

    Jules, Farah; Avedanian, Levon; Al-Khoury, Johny; Keita, Ramatoulaye; Normand, Alexandre; Bkaily, Ghassan; Jacques, Danielle

    2015-07-01

    In fetal human left ventricular endocardial endothelial cells (EECLs), both plasma membrane (PM) ET(A)R and ET(B)R were reported to mediate ET-1-induced increase of intracellular calcium [Ca](i); however, this effect was mediated by ET(A)R in right EECs (EECRs). In this study, we verified whether, as for the PM, nuclear membranes (NMs) ET-1 receptors activation in EECLs and EECRs induce an increase of nuclear calcium ([Ca](n)) and if this effect is mediated through the same receptor type as in PM. Using a plasmalemma-perforated technique and 3D confocal microscopy, our results showed that, as in PM intact cells, superfusion of nuclei of both cell types with cytosolic ET-1 induced a concentration-dependent sustained increase of [Ca](n). In EECRs, the ET(A)R antagonist prevented the effect of ET-1 on [Ca](n) without affecting EECLs. However, in both cell types, the effect of cytosolic ET-1 on [Ca](n) was prevented by the ETBR antagonist. In conclusion, both NMs' ET(A)R and ET(B)R mediated the effect of cytosolic ET-1 on [Ca](n) in EECRs. In contrast, only NMs' ET(B)R activation mediated the effect of cytosolic ET-1 in EECLs. Hence, the type of NMs' receptors mediating the effect of ET-1 on [Ca](n) are different from those of PM mediating the increase in [Ca](i).

  20. Circumferential guided wave measurements of a cylindrical fluid-filled bone-mimicking phantom.

    PubMed

    Nauleau, Pierre; Grimal, Quentin; Minonzio, Jean-Gabriel; Laugier, Pascal; Prada, Claire

    2014-02-01

    In the context of hip fracture risk prediction, measurement of guided waves could improve the assessment of cortical femoral neck properties. The decomposition of the time reversal operator (DORT) method was previously shown to be efficient to measure circumferential guided modes in an empty cortical bone-mimicking tube of circular cross section. In this study, an adaptation of the DORT method is proposed to probe the same bone-mimicking tube but filled with a marrow-mimicking fluid. The contributions to the backscattered field of waves multiply reflected in the cavity of the tube interfere with those of circumferential guided waves. The former contributions are eliminated in the backpropagation image using ad hoc criterion determined with simulation. Eight portions of different guided modes were observed from experimental and simulated data. They were identified by comparison with theoretical predictions. This work confirms the feasibility of measuring guided waves in a fluid-filled tube of bone-mimicking material with the DORT method.

  1. Smooth muscle-like tissue constructs with circumferentially oriented cells formed by the cell fiber technology.

    PubMed

    Hsiao, Amy Y; Okitsu, Teru; Onoe, Hiroaki; Kiyosawa, Mahiro; Teramae, Hiroki; Iwanaga, Shintaroh; Kazama, Tomohiko; Matsumoto, Taro; Takeuchi, Shoji

    2015-01-01

    The proper functioning of many organs and tissues containing smooth muscles greatly depends on the intricate organization of the smooth muscle cells oriented in appropriate directions. Consequently controlling the cellular orientation in three-dimensional (3D) cellular constructs is an important issue in engineering tissues of smooth muscles. However, the ability to precisely control the cellular orientation at the microscale cannot be achieved by various commonly used 3D tissue engineering building blocks such as spheroids. This paper presents the formation of coiled spring-shaped 3D cellular constructs containing circumferentially oriented smooth muscle-like cells differentiated from dedifferentiated fat (DFAT) cells. By using the cell fiber technology, DFAT cells suspended in a mixture of extracellular proteins possessing an optimized stiffness were encapsulated in the core region of alginate shell microfibers and uniformly aligned to the longitudinal direction. Upon differentiation induction to the smooth muscle lineage, DFAT cell fibers self-assembled to coiled spring structures where the cells became circumferentially oriented. By changing the initial core-shell microfiber diameter, we demonstrated that the spring pitch and diameter could be controlled. 21 days after differentiation induction, the cell fibers contained high percentages of ASMA-positive and calponin-positive cells. Our technology to create these smooth muscle-like spring constructs enabled precise control of cellular alignment and orientation in 3D. These constructs can further serve as tissue engineering building blocks for larger organs and cellular implants used in clinical treatments.

  2. Smooth Muscle-Like Tissue Constructs with Circumferentially Oriented Cells Formed by the Cell Fiber Technology

    PubMed Central

    Hsiao, Amy Y.; Okitsu, Teru; Onoe, Hiroaki; Kiyosawa, Mahiro; Teramae, Hiroki; Iwanaga, Shintaroh; Kazama, Tomohiko; Matsumoto, Taro; Takeuchi, Shoji

    2015-01-01

    The proper functioning of many organs and tissues containing smooth muscles greatly depends on the intricate organization of the smooth muscle cells oriented in appropriate directions. Consequently controlling the cellular orientation in three-dimensional (3D) cellular constructs is an important issue in engineering tissues of smooth muscles. However, the ability to precisely control the cellular orientation at the microscale cannot be achieved by various commonly used 3D tissue engineering building blocks such as spheroids. This paper presents the formation of coiled spring-shaped 3D cellular constructs containing circumferentially oriented smooth muscle-like cells differentiated from dedifferentiated fat (DFAT) cells. By using the cell fiber technology, DFAT cells suspended in a mixture of extracellular proteins possessing an optimized stiffness were encapsulated in the core region of alginate shell microfibers and uniformly aligned to the longitudinal direction. Upon differentiation induction to the smooth muscle lineage, DFAT cell fibers self-assembled to coiled spring structures where the cells became circumferentially oriented. By changing the initial core-shell microfiber diameter, we demonstrated that the spring pitch and diameter could be controlled. 21 days after differentiation induction, the cell fibers contained high percentages of ASMA-positive and calponin-positive cells. Our technology to create these smooth muscle-like spring constructs enabled precise control of cellular alignment and orientation in 3D. These constructs can further serve as tissue engineering building blocks for larger organs and cellular implants used in clinical treatments. PMID:25734774

  3. Efficacy of circumferential pulmonary vein ablation of atrial fibrillation in endurance athletes

    PubMed Central

    Calvo, Naiara; Mont, Lluís; Tamborero, David; Berruezo, Antonio; Viola, Graziana; Guasch, Eduard; Nadal, Mercè; Andreu, David; Vidal, Barbara; Sitges, Marta; Brugada, Josep

    2010-01-01

    Aims Long-term endurance sport practice has been increasingly recognized as a risk factor for lone atrial fibrillation (AF). However, data on the outcome of circumferential pulmonary vein ablation (CPVA) in endurance athletes are scarce. The aim of the study was to evaluate the efficacy of CPVA in AF secondary to endurance sport practice. Methods and results Patients submitted to CPVA answered a questionnaire about lifetime history of endurance sport practice. Endurance athletes were defined as those who engaged in >3 h per week of high-intensity exercise for at least the 10 years immediately preceding their AF diagnosis. A series of 182 consecutive patients was included (51 ± 11 years, 65% with paroxysmal AF, 81% men, 42 ± 6 mm mean left atrial diameter); 107 (59%) patients had lone AF, and 42 of them (23% of the study population) were classified as endurance athletes (lone AF sport group). Freedom from arrhythmia after a single CPVA was similar in the lone AF sport group compared with the remaining patients (P = 0.446). Left atrial size and long-standing AF were the only independent predictors for arrhythmia recurrence after ablation. Conclusion Circumferential pulmonary vein ablation was as effective in AF secondary to endurance sport practice as in other aetiologies of AF. PMID:19923171

  4. Circumferential wall tension due to hypertension plays a pivotal role in aorta remodelling.

    PubMed

    Prado, Cibele M; Rossi, Marcos A

    2006-12-01

    The present study was carried out to investigate the role of hypertension in the genesis and localization of intimal lesions and medial remodelling found in the prestenotic segment in relation to a severe stenosis of the abdominal aorta just below the diaphragm. Male young rats were divided randomly into operated group, animals submitted to surgical abdominal aorta stenosis, and sham-operated group, a control group of animals submitted to sham operation to simulate abdominal aorta stenosis. Aortas in the hypertensive prestenotic segment with increased circumferential wall tension associated with normal tensile stress, laminar flow/normal wall shear stress were characterized by enlarged heterogeneous endothelial cells elongated in the direction of the blood flow, diffusely distributed conspicuous neointimal plaques and medial thickening. The immunohistochemical analysis revealed an increased expression of eNOS, iNOS, nitrotyrosine and transforming growth factor-beta (TGF-beta) in endothelial cells and/or smooth muscle cells in this segment. Our findings suggest that increased circumferential wall tension due to hypertension plays a pivotal role in the remodelling of the prestenotic segment through biomechanical effects on oxidative stress and increased TGF-beta expression. Further studies are needed to clarify the intrinsic pathogenetic mechanism of focal distribution of the neointimal plaques in the hypertensive segment.

  5. Recent evaluations of crack-opening-area in circumferentially cracked pipes

    SciTech Connect

    Rahman, S.; Brust, F.; Ghadiali, N.; Wilkowski, G.; Miura, N.

    1997-04-01

    Leak-before-break (LBB) analyses for circumferentially cracked pipes are currently being conducted in the nuclear industry to justify elimination of pipe whip restraints and jet shields which are present because of the expected dynamic effects from pipe rupture. The application of the LBB methodology frequently requires calculation of leak rates. The leak rates depend on the crack-opening area of the through-wall crack in the pipe. In addition to LBB analyses which assume a hypothetical flaw size, there is also interest in the integrity of actual leaking cracks corresponding to current leakage detection requirements in NRC Regulatory Guide 1.45, or for assessing temporary repair of Class 2 and 3 pipes that have leaks as are being evaluated in ASME Section XI. The objectives of this study were to review, evaluate, and refine current predictive models for performing crack-opening-area analyses of circumferentially cracked pipes. The results from twenty-five full-scale pipe fracture experiments, conducted in the Degraded Piping Program, the International Piping Integrity Research Group Program, and the Short Cracks in Piping and Piping Welds Program, were used to verify the analytical models. Standard statistical analyses were performed to assess used to verify the analytical models. Standard statistical analyses were performed to assess quantitatively the accuracy of the predictive models. The evaluation also involved finite element analyses for determining the crack-opening profile often needed to perform leak-rate calculations.

  6. Reconstructive options after total laryngectomy with subtotal or circumferential hypopharyngectomy and cervical esophagectomy.

    PubMed

    Piazza, Cesare; Taglietti, Valentina; Nicolai, Piero

    2012-04-01

    The present review is focused on the main reconstructive options currently used after partial or circumferential resection of the hypopharynx and cervical esophagus. The advantages and disadvantages of pectoralis major myocutaneous (PMMC) pedicled flap, fasciocutaneous free flaps as radial forearm and anterolateral thigh (ALT), and visceral free grafts like jejunum and gastro-omental are overviewed. For partial hypopharyngeal defects with limited extension to the cervical esophagus, no specific pedicled or free flap is deemed superior over others: the patient's body habitus and surgeon's preference remain the most important factors affecting the reconstructive choice. In contrast, after circumferential hypopharyngectomy, pharyngocutaneous fistula (PCF) and stricture rates of PMMC are higher than those obtained by free flaps. In the most recent series applying ALT and jejunum, PCF and stricture occurrence is comparable, whereas reduced mortality, overall complication rate, and donor-site morbidity of ALT and its better swallowing and speech outcomes have contributed to make this option progressively more popular. On the other hand, gastro-omental seems to offer an unparalleled amount of highly vascularized tissue to manage the difficult situation of salvage surgery after chemoradiation, even though complication rates remain not negligible and this technique has not been widely adopted. The reconstructive armamentarium of head and neck surgeons involved in hypopharyngeal and cervical esophagus reconstruction should encompass every option described herein in order to appropriately deal with specific clinical needs and patient requirements. However, fasciocutaneous free flaps (especially ALT) seem to play an ever greater role in restoration of pharyngoesophageal continuity.

  7. Parameter measurement of the cylindrically curved thin layer using low-frequency circumferential Lamb waves.

    PubMed

    Chen, Xiao; Wan, Mingxi

    2005-03-01

    The characteristic parameters of a cylindrically curved thin layer include its elastic constants, thickness and curved radius. A layer is considered thin if the echoes from the front and back surfaces of the layer cannot be separated in the time domain, and/or that the wave arrivals corresponding to longitudinal and shear wave part cannot be identified in the time or space domain. This paper describes a low-frequency circumferential Lamb wave method to characterize those parameters of a cylindrically curved thin layer. The technique is based on the measurement of circumferential Lamb wave phase velocity and the unknown parameter is estimated through minimizing the mean square error obtained by comparing theoretical and experimental phase velocities. The sensitivity and accuracy of the proposed technique to different parameters are analyzed. Using the present technique, a cylindrically curved thin layer with thickness down to ten percent of the longitudinal wavelength can be successfully measured with an average relative error less than two-percent in our experiment.

  8. Nonlinear Local Bending Response and Bulging Factors for Longitudinal and Circumferential Cracks in Pressurized Cylindrical Shells

    NASA Technical Reports Server (NTRS)

    Young, Richard D.; Rose, Cheryl A.; Starnes, James H., Jr.

    2000-01-01

    Results of a geometrically nonlinear finite element parametric study to determine curvature correction factors or bulging factors that account for increased stresses due to curvature for longitudinal and circumferential cracks in unstiffened pressurized cylindrical shells are presented. Geometric parameters varied in the study include the shell radius, the shell wall thickness, and the crack length. The major results are presented in the form of contour plots of the bulging factor as a function of two nondimensional parameters: the shell curvature parameter, lambda, which is a function of the shell geometry, Poisson's ratio, and the crack length; and a loading parameter, eta, which is a function of the shell geometry, material properties, and the applied internal pressure. These plots identify the ranges of the shell curvature and loading parameters for which the effects of geometric nonlinearity are significant. Simple empirical expressions for the bulging factor are then derived from the numerical results and shown to predict accurately the nonlinear response of shells with longitudinal and circumferential cracks. The numerical results are also compared with analytical solutions based on linear shallow shell theory for thin shells, and with some other semi-empirical solutions from the literature, and limitations on the use of these other expressions are suggested.

  9. Bone Regenerative Potential of Enamel Matrix Protein in the Circumferential Defect Around a Dental Implant.

    PubMed

    Lim, Hyun-Chang; Lee, Jung-Seok; Jung, Ui-Won; Choi, Seong-Ho

    2016-04-01

    The aim of this study was to determine the bone regenerative potential of enamel matrix derivative (EMD) in a defect around a dental implant. Five mongrel dogs were used. A circumferential defect was created around osteotomies that had been fabricated to receive titanium implants. The defects were treated with EMD, biphasic calcium phosphate (BCP), a mixture of EMD and BCP (EBCP), or blood coagulum (control). In general, the amount of new bone formation, the most-coronal level of bone-implant contact, defect fill, and bone-implant contact ratio were greater in the EMD group than in the control group, but the differences did not reach statistical significance. The EBCP group yielded no beneficial effect in new bone formation. Histologically, there was no notable difference in healing pattern between the EMD group and the control, and the EBCP and the BCP group. Few of the specimens in the EMD and EBCP groups exhibited remarkable bone regeneration. Neither EMD alone nor a mixture of BCP and EMD enhanced bone healing in a circumferential gap defect around a dental implant.

  10. Mutations in Either TUBB or MAPRE2 Cause Circumferential Skin Creases Kunze Type

    PubMed Central

    Isrie, Mala; Breuss, Martin; Tian, Guoling; Hansen, Andi Harley; Cristofoli, Francesca; Morandell, Jasmin; Kupchinsky, Zachari A.; Sifrim, Alejandro; Rodriguez-Rodriguez, Celia Maria; Dapena, Elena Porta; Doonanco, Kurston; Leonard, Norma; Tinsa, Faten; Moortgat, Stéphanie; Ulucan, Hakan; Koparir, Erkan; Karaca, Ender; Katsanis, Nicholas; Marton, Valeria; Vermeesch, Joris Robert; Davis, Erica E.; Cowan, Nicholas J.; Keays, David Anthony; Van Esch, Hilde

    2015-01-01

    Circumferential skin creases Kunze type (CSC-KT) is a specific congenital entity with an unknown genetic cause. The disease phenotype comprises characteristic circumferential skin creases accompanied by intellectual disability, a cleft palate, short stature, and dysmorphic features. Here, we report that mutations in either MAPRE2 or TUBB underlie the genetic origin of this syndrome. MAPRE2 encodes a member of the microtubule end-binding family of proteins that bind to the guanosine triphosphate cap at growing microtubule plus ends, and TUBB encodes a β-tubulin isotype that is expressed abundantly in the developing brain. Functional analyses of the TUBB mutants show multiple defects in the chaperone-dependent tubulin heterodimer folding and assembly pathway that leads to a compromised yield of native heterodimers. The TUBB mutations also have an impact on microtubule dynamics. For MAPRE2, we show that the mutations result in enhanced MAPRE2 binding to microtubules, implying an increased dwell time at microtubule plus ends. Further, in vivo analysis of MAPRE2 mutations in a zebrafish model of craniofacial development shows that the variants most likely perturb the patterning of branchial arches, either through excessive activity (under a recessive paradigm) or through haploinsufficiency (dominant de novo paradigm). Taken together, our data add CSC-KT to the growing list of tubulinopathies and highlight how multiple inheritance paradigms can affect dosage-sensitive biological systems so as to result in the same clinical defect. PMID:26637975

  11. Fracture behavior of circumferentially surface-cracked elbows. Technical report, October 1993--March 1996

    SciTech Connect

    Kilinski, T.; Mohan, R.; Rudland, D.; Fleming, M.

    1996-12-01

    This report presents the results from Task 2 of the Second International Piping Integrity Research Group (IPIRG-2) program. The focus of the Task 2 work was directed towards furthering the understanding of the fracture behavior of long-radius elbows. This was accomplished through a combined analytical and experimental program. J-estimation schemes were developed for both axial and circumferential surface cracks in elbows. Large-scale, quasi-static and dynamic, pipe-system, elbow fracture experiments under combined pressure and bending loads were performed on elbows containing an internal surface crack at the extrados. In conjunction with the elbow experiments, material property data were developed for the A106-90 carbon steel and WP304L stainless steel elbow materials investigated. A comparison of the experimental data with the maximum stress predictions using existing straight pipe fracture prediction analysis methods, and elbow fracture prediction methods developed in this program was performed. This analysis was directed at addressing the concerns regarding the validity of using analysis predictions developed for straight pipe to predict the fracture stresses of cracked elbows. Finally, a simplified fitting flaw acceptance criteria incorporating ASME B2 stress indices and straight pipe, circumferential-crack analysis was developed.

  12. Circumferential flow of particles in the suprachoroidal space is impeded by the posterior ciliary arteries

    PubMed Central

    Chiang, Bryce; Kim, Yoo Chun; Edelhauser, Henry F.; Prausnitz, Mark R.

    2016-01-01

    Microneedle injection into the suprachoroidal space (SCS) enables targeted drug delivery for treatment of posterior segment diseases (e.g., posterior uveitis). This study sought to identify and characterize anatomical barriers to circumferential spread of particles in the SCS of rabbit and human cadaver eyes. These barriers could make targeting specific regions within the SCS challenging. A hollow microneedle (33-gauge, 750 μm long) was used to inject fluorescent particles into albino New Zealand White rabbit eyes ex vivo at six different positions around the limbus and a limited number of conditions in vivo. SCS injections were also performed in human cadaver eyes 8 mm and 2 mm from the optic nerve (ON). Eyes were dissected and particle distribution was quantified. In rabbit eyes, injections made in the superior or inferior hemispheres (even when injected temporally immediately adjacent to the long posterior ciliary artery (LPCA)) did not significantly cross into the other hemisphere, apparently due to a barrier formed by the LPCA. The vortex veins had a minor effect on particle deposition, limited to only around the vortex vein root. In human eyes, the short posterior ciliary arteries (SPCAs) prevented circumferential spread towards the macula and ON. In conclusion, the rabbit LPCA and the human SPCA were anatomical barriers to particle spread within the SCS. Therefore, design of drug delivery protocols targeting the SCS need to account for barriers formed by anatomical structures in order for injected drug to reach target tissues. PMID:26976663

  13. Determination of the axial and circumferential mechanical properties of the skin tissue using experimental testing and constitutive modeling.

    PubMed

    Karimi, Alireza; Navidbakhsh, Mahdi; Haghighatnama, Maedeh; Haghi, Afsaneh Motevalli

    2015-01-01

    The skin, being a multi-layered material, is responsible for protecting the human body from the mechanical, bacterial, and viral insults. The skin tissue may display different mechanical properties according to the anatomical locations of a body. However, these mechanical properties in different anatomical regions and at different loading directions (axial and circumferential) of the mice body to date have not been determined. In this study, the axial and circumferential loads were imposed on the mice skin samples. The elastic modulus and maximum stress of the skin tissues were measured before the failure occurred. The nonlinear mechanical behavior of the skin tissues was also computationally investigated through a suitable constitutive equation. Hyperelastic material model was calibrated using the experimental data. Regardless of the anatomic locations of the mice body, the results revealed significantly different mechanical properties in the axial and circumferential directions and, consequently, the mice skin tissue behaves like a pure anisotropic material. The highest elastic modulus was observed in the back skin under the circumferential direction (6.67 MPa), while the lowest one was seen in the abdomen skin under circumferential loading (0.80 MPa). The Ogden material model was narrowly captured the nonlinear mechanical response of the skin at different loading directions. The results help to understand the isotropic/anisotropic mechanical behavior of the skin tissue at different anatomical locations. They also have implications for a diversity of disciplines, i.e., dermatology, cosmetics industry, clinical decision making, and clinical intervention.

  14. Sea Ice Concentration and Extent

    NASA Technical Reports Server (NTRS)

    Comiso, Josefino C.

    2014-01-01

    Among the most seasonal and most dynamic parameters on the surface of the Earth is sea ice which at any one time covers about 3-6% of the planet. In the Northern Hemisphere, sea ice grows in extent from about 6 x 10(exp 6) sq km to 16 x 10(exp 6) sq km, while in the Southern Hemisphere, it grows from about 3 x 10(exp 6) sq km to about 19 x 10(exp 6) sq km (Comiso, 2010; Gloersen et al., 1992). Sea ice is up to about 2-3 m thick in the Northern Hemisphere and about 1 m thick in the Southern Hemisphere (Wadhams, 2002), and compared to the average ocean depth of about 3 km, it is a relatively thin, fragile sheet that can break due to waves and winds or melt due to upwelling of warm water. Being constantly advected by winds, waves, and currents, sea ice is very dynamic and usually follows the directions of the many gyres in the polar regions. Despite its vast expanse, the sea ice cover was previously left largely unstudied and it was only in recent years that we have understood its true impact and significance as related to the Earths climate, the oceans, and marine life.

  15. Sea Ice Concentration and Extent

    NASA Technical Reports Server (NTRS)

    Comiso, Josefino C.

    2014-01-01

    Among the most seasonal and most dynamic parameters on the surface of the Earth is sea ice which at any one time covers about 3-6% of the planet. In the Northern Hemisphere, sea ice grows in extent from about 6 x 10(exp 6) sq km to 16 x 10(exp 6) sq km, while in the Southern Hemisphere, it grows from about 3 x 10(exp 6) sq km to about 19 x 10(exp 6) sq km (Comiso, 2010; Gloersen et al., 1992). Sea ice is up to about 2-3 m thick in the Northern Hemisphere and about 1 m thick in the Southern Hemisphere (Wadhams, 2002), and compared to the average ocean depth of about 3 km, it is a relatively thin, fragile sheet that can break due to waves and winds or melt due to upwelling of warm water. Being constantly advected by winds, waves, and currents, sea ice is very dynamic and usually follows the directions of the many gyres in the polar regions. Despite its vast expanse, the sea ice cover was previously left largely unstudied and it was only in recent years that we have understood its true impact and significance as related to the Earths climate, the oceans, and marine life.

  16. The pattern of circumferential and radial eruptive fissures on the volcanoes of Fernandina and Isabela islands, Galapagos

    USGS Publications Warehouse

    Chadwick, W.W.; Howard, K.A.

    1991-01-01

    Maps of the eruptive vents on the active shield volcanoes of Fernandina and Isabela islands, Galapagos, made from aerial photographs, display a distinctive pattern that consists of circumferential eruptive fissures around the summit calderas and radial fissures lower on the flanks. On some volcano flanks either circumferential or radial eruptions have been dominant in recent time. The location of circumferential vents outside the calderas is independent of caldera-related normal faults. The eruptive fissures are the surface expression of dike emplacement, and the dike orientations are interpreted to be controlled by the state of stress in the volcano. Very few subaerial volcanoes display a pattern of fissures similar to that of the Galapagos volcanoes. Some seamounts and shield volcanoes on Mars morphologically resemble the Galapagos volcanoes, but more specific evidence is needed to determine if they also share common structure and eruptive style. ?? 1991 Springer-Verlag.

  17. Ultrasound-guided perineural injection for nerve blockade: Does a single-sided injection produce circumferential nerve coverage?

    PubMed

    Nwawka, O Kenechi; Miller, Theodore T; Jawetz, Shari T; Saboeiro, Gregory R

    2016-10-01

    Our current clinical technique for sonographic-guided perineural injection consists of two-sided perineural needle placement to obtain circumferential distribution of the injectate. This study aimed to determine if a single-side needle position will produce circumferential nerve coverage. Fresh-frozen cadaveric specimens were used for this study. In six upper extremities, a needle was positioned along the deep surface of median, radial, and ulnar nerves in the carpal tunnel, radial tunnel, and cubital tunnel, respectively, and 2 ml of contrast was injected for each nerve. In three pelvic specimens, a needle was positioned deep to the sciatic nerves bilaterally, and 5 ml of contrast was injected. An additional four median nerve injections were performed using superficial surface needle position. The specimens then underwent CT scanning to assess the distribution of the perineural contrast medium. One hundred percent of the radial, ulnar, and sciatic nerves demonstrated circumferential distribution on CT. Only 50% of the median nerve injections with the needle placed deep to the nerve produced circumferential coverage, whereas 100% of median nerves injected with the needle between the nerve and retinaculum demonstrated circumferential coverage. The average length of spread of perineural injectate was 11.6 cm in the upper extremity and 10.3 cm for the sciatic nerves. Using clinical volumes of fluid, needle positioning at the deep surface of upper extremity and sciatic nerves was sufficient to produce circumferential coating of the nerve, except in the carpal tunnel, where placement of the needle between the nerve and flexor retinaculum is recommended. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 44:465-469, 2016. © 2016 Wiley Periodicals, Inc.

  18. Halo traction, single-segment circumferential fixation treating cervical tubercular spondylitis with kyphosis.

    PubMed

    Zeng, Hao; Liang, Yingfang; Wang, Xiyang; Shen, Xiongjie; Luo, Chengke; Xu, Zhengquan; Liu, Zheng; Zhang, Yupeng

    2015-11-01

    To evaluate the clinical efficacy and feasibility of twenty patients with cervical tubercular spondylitis with kyphosis (CTSK) treated by halo traction, single-segment circumferential instrumented fusion combined anterior debridement, decompression and bone grafting. Retrospective review of data on twenty patients who suffered from CTSK admitted to our hospital between January 2007 and December 2012. All of them were performed by halo traction, single-segment circumferential instrumented fusion (anterior titanium plate and posterior pedicle or lateral mass fixation) combined anterior debridement, decompression and titanium mesh cage (TMC) filled with allograft bone particles. X-ray and computed tomographic (CT) images were used to determined sagittal balance and bone fusion. The clinical efficacy was evaluated using statistical analysis about the visual analogue scale (VAS) scores of pain, neurological status according to the Frankel classification and erythrocyte sedimentation rate (ESR), which were collected at certain time. The average follow-up period was 34.1 ± 7.0 months (24-48 months). In the 20 cases, no obvious postoperative complications related to instrumentation and bone grafting and neurologic function was improved in various degrees. The average pretreatment ESR was 46.4 ± 21.7 mm/h, which got normal within 3 months in all patients. The average VAS on admission was 6.7 ± 1.7, which decreased to 1.6 ± 1.1 postoperatively. All patients got bony fusion within 3.4-5.5 months after surgery. The Cobb angle of 30.8 ± 10.5° on admission reduced to 2.9 ± 3.9° performed by preoperative halo traction, became to -5.1 ± 4.0° after operation and remained at -4.3 ± 3.8°, with 0.9 ± 0.7° of correction loss. Halo traction, single-segment circumferential instrumented fusion combined anterior debridement, decompression and TMC can be an effective and safe treatment method for the treatment of cervical tubercular spondylitis with kyphosis and the

  19. Global Bi-ventricular endocardial distribution of activation rate during long duration ventricular fibrillation in normal and heart failure canines.

    PubMed

    Luo, Qingzhi; Jin, Qi; Zhang, Ning; Han, Yanxin; Wang, Yilong; Huang, Shangwei; Lin, Changjian; Ling, Tianyou; Chen, Kang; Pan, Wenqi; Wu, Liqun

    2017-04-13

    The objective of this study was to detect differences in the distribution of the left and right ventricle (LV & RV) activation rate (AR) during short-duration ventricular fibrillation (SDVF, <1 min) and long-duration ventricular fibrillation VF (LDVF, >1 min) in normal and heart failure (HF) canine hearts. Ventricular fibrillation (VF) was electrically induced in six healthy dogs (control group) and six dogs with right ventricular pacing-induced congestive HF (HF group). Two 64-electrode basket catheters deployed in the LV and RV were used for global endocardium electrical mapping. The AR of VF was estimated by fast Fourier transform analysis from each electrode. In the control group, the LV was activated faster than the RV in the first 20 s, after which there was no detectable difference in the AR between them. When analyzing the distribution of the AR within the bi-ventricles at 3 min of LDVF, the posterior LV was activated fastest, while the anterior was slowest. In the HF group, a detectable AR gradient existed between the two ventricles within 3 min of VF, with the LV activating more quickly than the RV. When analyzing the distribution of the AR within the bi-ventricles at 3 min of LDVF, the septum of the LV was activated fastest, while the anterior was activated slowest. A global bi-ventricular endocardial AR gradient existed within the first 20 s of VF but disappeared in the LDVF in healthy hearts. However, the AR gradient was always observed in both SDVF and LDVF in HF hearts. The findings of this study suggest that LDVF in HF hearts can be maintained differently from normal hearts, which accordingly should lead to the development of different management strategies for LDVF resuscitation.

  20. PITX2 Loss-of-Function Mutation Contributes to Congenital Endocardial Cushion Defect and Axenfeld-Rieger Syndrome

    PubMed Central

    Zhao, Cui-Mei; Peng, Lu-Ying; Li, Li; Liu, Xing-Yuan; Wang, Juan; Zhang, Xian-Ling; Yuan, Fang; Li, Ruo-Gu; Qiu, Xing-Biao; Yang, Yi-Qing

    2015-01-01

    Congenital heart disease (CHD), the most common type of birth defect, is still the leading non-infectious cause of infant morbidity and mortality in humans. Aggregating evidence demonstrates that genetic defects are involved in the pathogenesis of CHD. However, CHD is genetically heterogeneous and the genetic components underpinning CHD in an overwhelming majority of patients remain unclear. In the present study, the coding exons and flanking introns of the PITX2 gene, which encodes a paired-like homeodomain transcription factor 2essential for cardiovascular morphogenesis as well as maxillary facial development, was sequenced in 196 unrelated patients with CHD and subsequently in the mutation carrier’s family members available. As a result, a novel heterozygous PITX2 mutation, p.Q102X for PITX2a, or p.Q148X for PITX2b, or p.Q155X for PITX2c, was identified in a family with endocardial cushion defect (ECD) and Axenfeld-Rieger syndrome (ARS). Genetic analysis of the pedigree showed that the nonsense mutation co-segregated with ECD and ARS transmitted in an autosomal dominant pattern with complete penetrance. The mutation was absent in 800 control chromosomes from an ethnically matched population. Functional analysis by using a dual-luciferase reporter assay system revealed that the mutant PITX2 had no transcriptional activity and that the mutation eliminated synergistic transcriptional activation between PITX2 and NKX2.5, another transcription factor pivotal for cardiogenesis. To our knowledge, this is the first report on the association of PITX2 loss-of-function mutation with increased susceptibility to ECD and ARS. The findings provide novel insight into the molecular mechanisms underpinning ECD and ARS, suggesting the potential implications for the antenatal prophylaxis and personalized treatment of CHD and ARS. PMID:25893250

  1. Myocardial Tbx20 regulates early atrioventricular canal formation and endocardial epithelial-mesenchymal transition via Bmp2.

    PubMed

    Cai, Xiaoqiang; Nomura-Kitabayashi, Aya; Cai, Weibin; Yan, Jianyun; Christoffels, Vincent M; Cai, Chen-Leng

    2011-12-15

    During early embryogenesis, the formation of the cardiac atrioventricular canal (AVC) facilitates the transition of the heart from a linear tube into a chambered organ. However, the genetic pathways underlying this developmental process are poorly understood. The T-box transcription factor Tbx20 is expressed predominantly in the AVC of early heart tube. It was shown that Tbx20 activates Nmyc1 and suppresses Tbx2 expression to promote proliferation and specification of the atrial and ventricular chambers, yet it is not known if Tbx20 is involved in early AVC development. Here, we report that mice lacking Tbx20 in the AVC myocardium fail to form the AVC constriction, and the endocardial epithelial-mesenchymal transition (EMT) is severely perturbed. Tbx20 maintains expression of a variety of genes, including Bmp2, Tbx3 and Hand1 in the AVC myocardium. Intriguingly, we found Bmp2 downstream genes involved in the EMT initiation are also downregulated. In addition, re-expression of Bmp2 in the AVC myocardium substantially rescues the EMT defects resulting from the lack of Tbx20, suggesting Bmp2 is one of the key downstream targets of Tbx20 in AVC development. Our data support a complex signaling network with Tbx20 suppressing Tbx2 in the AVC myocardium but also indirectly promoting Tbx2 expression through Bmp2. The spatiotemporal expression of Tbx2 in the AVC appears to be balanced between these two opposing signals. Overall, our study provides genetic evidence that Tbx20 has essential roles in regulating AVC development that coordinate early cardiac chamber formation.

  2. PITX2 Loss-of-Function Mutation Contributes to Congenital Endocardial Cushion Defect and Axenfeld-Rieger Syndrome.

    PubMed

    Zhao, Cui-Mei; Peng, Lu-Ying; Li, Li; Liu, Xing-Yuan; Wang, Juan; Zhang, Xian-Ling; Yuan, Fang; Li, Ruo-Gu; Qiu, Xing-Biao; Yang, Yi-Qing

    2015-01-01

    Congenital heart disease (CHD), the most common type of birth defect, is still the leading non-infectious cause of infant morbidity and mortality in humans. Aggregating evidence demonstrates that genetic defects are involved in the pathogenesis of CHD. However, CHD is genetically heterogeneous and the genetic components underpinning CHD in an overwhelming majority of patients remain unclear. In the present study, the coding exons and flanking introns of the PITX2 gene, which encodes a paired-like homeodomain transcription factor 2essential for cardiovascular morphogenesis as well as maxillary facial development, was sequenced in 196 unrelated patients with CHD and subsequently in the mutation carrier's family members available. As a result, a novel heterozygous PITX2 mutation, p.Q102X for PITX2a, or p.Q148X for PITX2b, or p.Q155X for PITX2c, was identified in a family with endocardial cushion defect (ECD) and Axenfeld-Rieger syndrome (ARS). Genetic analysis of the pedigree showed that the nonsense mutation co-segregated with ECD and ARS transmitted in an autosomal dominant pattern with complete penetrance. The mutation was absent in 800 control chromosomes from an ethnically matched population. Functional analysis by using a dual-luciferase reporter assay system revealed that the mutant PITX2 had no transcriptional activity and that the mutation eliminated synergistic transcriptional activation between PITX2 and NKX2.5, another transcription factor pivotal for cardiogenesis. To our knowledge, this is the first report on the association of PITX2 loss-of-function mutation with increased susceptibility to ECD and ARS. The findings provide novel insight into the molecular mechanisms underpinning ECD and ARS, suggesting the potential implications for the antenatal prophylaxis and personalized treatment of CHD and ARS.

  3. Myocardial Tbx20 regulates early atrioventricular canal formation and endocardial epithelial-mesenchymal transition via Bmp2

    PubMed Central

    Cai, Xiaoqiang; Nomura-Kitabayashi, Aya; Cai, Weibin; Yan, Jianyun; Christoffels, Vincent M.; Cai, Chen-Leng

    2011-01-01

    During early embryogenesis, the formation of the cardiac atrioventricular canal (AVC) facilitates the transition of the heart from a linear tube into a chambered organ. However, the genetic pathways underlying this developmental process are poorly understood. The T-box transcription factor Tbx20 is expressed predominantly in the AVC of early heart tube. It was shown that Tbx20 activates Nmyc1 and suppresses Tbx2 expression to promote proliferation and specification of the atrial and ventricular chambers, yet it is not known if Tbx20 is involved in early AVC development. Here, we report that mice lacking Tbx20 in the AVC myocardium fail to form the AVC constriction, and the endocardial epithelial-mesenchymal transition (EMT) is severely perturbed. Tbx20 maintains expression of a variety of genes, including Bmp2, Tbx3 and Hand1 in the AVC myocardium. Intriguingly, we found Bmp2 downstream genes involved in the EMT initiation are also downregulated. In addition, re-expression of Bmp2 in the AVC myocardium substantially rescues the EMT defects resulting from the lack of Tbx20, suggesting Bmp2 is one of the key downstream targets of Tbx20 in AVC development. Our data support a complex signaling network with Tbx20 suppressing Tbx2 in the AVC myocardium but also indirectly promoting Tbx2 expression through Bmp2. The spatiotemporal expression of Tbx2 in the AVC appears to be balanced between these two opposing signals. Overall, our study provides genetic evidence that Tbx20 has essential roles in regulating AVC development that coordinate early cardiac chamber formation. PMID:21983003

  4. The role of infarct transmural extent in infarct extension: A computational study.

    PubMed

    Leong, Chin-Neng; Lim, Einly; Andriyana, Andri; Al Abed, Amr; Lovell, Nigel Hamilton; Hayward, Christopher; Hamilton-Craig, Christian; Dokos, Socrates

    2017-02-01

    Infarct extension, a process involving progressive extension of the infarct zone (IZ) into the normally perfused border zone (BZ), leads to continuous degradation of the myocardial function and adverse remodelling. Despite carrying a high risk of mortality, detailed understanding of the mechanisms leading to BZ hypoxia and infarct extension remains unexplored. In the present study, we developed a 3D truncated ellipsoidal left ventricular model incorporating realistic electromechanical properties and fibre orientation to examine the mechanical interaction among the remote, infarct and BZs in the presence of varying infarct transmural extent (TME). Localized highly abnormal systolic fibre stress was observed at the BZ, owing to the simultaneous presence of moderately increased stiffness and fibre strain at this region, caused by the mechanical tethering effect imposed by the overstretched IZ. Our simulations also demonstrated the greatest tethering effect and stress in BZ regions with fibre direction tangential to the BZ-remote zone boundary. This can be explained by the lower stiffness in the cross-fibre direction, which gave rise to a greater stretching of the IZ in this direction. The average fibre strain of the IZ, as well as the maximum stress in the sub-endocardial layer, increased steeply from 10% to 50% infarct TME, and slower thereafter. Based on our stress-strain loop analysis, we found impairment in the myocardial energy efficiency and elevated energy expenditure with increasing infarct TME, which we believe to place the BZ at further risk of hypoxia. Copyright © 2016 John Wiley & Sons, Ltd.

  5. Development of circumferential seal for helicopter transmissions: Results of bench and flight tests

    NASA Technical Reports Server (NTRS)

    Strom, T. N.; Ludwig, L. P.

    1975-01-01

    A modified circumferential segmented ring seal was designed for direct replacement of a helicopter transmission elastomeric lip seal operating on a shaft diameter of 13.91 centimeters (5.481 in.) at sliding velocities to 52.48 m/sec (10 330 ft/min). The modifications involved the garter spring tension, shaft roundness, seal housing flatness, and pumping grooves to inhibit leakage. Operation of the seals in bench tests under simulated helicopter transmission conditions revealed that the seal leakage rate was within acceptable limits and that the wear rate was negligible. The low leakage and wear rates were confirmed in flight tests of 600 and 175 hours (sliding speed, 48.11 m/sec (9470 ft/min)). An additional 200 hours of air worthiness qualification testing (aircraft tie down) demonstrated that the seal can operate at the advanced sliding conditions of 52.48 m/sec (10 330 ft/min).

  6. Crack shape developments and leak rates for circumferential complex-cracked pipes

    SciTech Connect

    Brickstad, B.; Bergman, M.

    1997-04-01

    A computerized procedure has been developed that predicts the growth of an initial circumferential surface crack through a pipe and further on to failure. The crack growth mechanism can either be fatigue or stress corrosion. Consideration is taken to complex crack shapes and for the through-wall cracks, crack opening areas and leak rates are also calculated. The procedure is based on a large number of three-dimensional finite element calculations of cracked pipes. The results from these calculations are stored in a database from which the PC-program, denoted LBBPIPE, reads all necessary information. In this paper, a sensitivity analysis is presented for cracked pipes subjected to both stress corrosion and vibration fatigue.

  7. New circumferential seal design concept using self-acting lift geometries

    NASA Technical Reports Server (NTRS)

    Hady, W. F.; Ludwig, L. P.

    1972-01-01

    Seal operating temperatures, leakage (pressurizing gas flow), torque, and wear of a conventional circumferential shaft seal were measured and compared to those of a conventional seal modified to have self-acting lift geometries. Both seal types had a 2.625-in diameter bore and were operated at a sliding velocity of 150 ft/sec with differential pressures ranging from 0 to 100 psi. Results of this investigation show that the self-acting seal operated at lower bulk carbon temperatures with half the torque and approximately one-tenth the wear of the conventional seal. Seal leakage of the self-acting seal was of order of 0.04 scfm for pressures above 60 psi which is well within the accepted range for gas turbine engine applications.

  8. Stress intensity magnification factors for fully circumferential cracks in valve bodies (thick cylinders)

    SciTech Connect

    Toor, P.M.

    1998-11-01

    The stress intensity solutions presented herein were obtained using an energy method in conjunction with a two-dimensional finite element program in order to explicitly account for curvature effect for fully circumferential cracks. The magnification factors for a specific crack depth were calculated by successively loading the crack surface by a uniform, linear, quadratic, and a cubic loading distribution. The magnification factors can be used to calculate the stress intensity factors by superposition method. The functions for each load condition in terms of radius to thickness ratio (R/t) and a fractional distance in terms of crack depth to thickness ratio (a/t) were developed. The validity of these functions is R/t = 1.5 to 10.0 and for 0.0125 {le} a/t {le} 0.8125. The functions agree to within 1% of the finite elements solutions for most magnification factors.

  9. Soil sampling device with latch assembly having a variable circumferential shape

    DOEpatents

    Meyer, R.D.

    1996-12-24

    The invention relates to an improved sampler which can be operated in any orientation. The design features a positive gripping of the operating rod in a manner to reduce point loads so as to reduce any possibility of jamming of the rod on a retraction stroke until such time as it is positively retained in the fully withdrawn position. In the preferred embodiment, a pair of mating cylindrical latch pieces, held together by a circumferential spring, are used for positive actuation. The inner rod has an angular cut-out which provides the base for the latch when aligned with the latch. A release fixture can be used to free the latch from the cone rod after actuation. The latches are formed in such a manner as they may support themselves within the housing of the sampler until they engage the operating rod. 11 figs.

  10. Soil sampling device with latch assembly having a variable circumferential shape

    DOEpatents

    Meyer, Robert D.

    1996-01-01

    The invention relates to an improved sampler which can be operated in any orientation. The design features a positive gripping of the operating rod in a manner to reduce point loads so as to reduce any possibility of jamming of the rod on a retraction stroke until such time as it is positively retained in the fully withdrawn position. In the preferred embodiment, a pair of mating cylindrical latch pieces, held together by a circumferential spring, are used for positive actuation. The inner rod has an angular cut-out which provides the base for the latch when aligned with the latch. A release fixture can be used to free the latch from the cone rod after actuation. The latches are formed in such a manner as they may support themselves within the housing of the sampler until they engage the operating rod.

  11. Development of a used fuel cladding damage model incorporating circumferential and radial hydride responses

    NASA Astrophysics Data System (ADS)

    Chen, Qiushi; Ostien, Jakob T.; Hansen, Glen

    2014-04-01

    At the completion of the fuel drying process, used fuel Zry4 cladding typically exhibits a significant population of δ-hydride inclusions. These inclusions are in the form of small platelets that are generally oriented both circumferentially and radially within the cladding material. There is concern that radially-oriented hydride inclusions may weaken the cladding material and lead to issues during used fuel storage and transportation processes. A high fidelity model of the mechanical behavior of hydrides has utility in both designing fuel cladding to be more resistant to this hydride-induced weakening and also in suggesting modifications to drying, storage, and transport operations to reduce the impact of hydride formation and/or the avoidance of loading scenarios that could overly stress the radial inclusions. We develop a mechanical model for the Zry4-hydride system that, given a particular morphology of hydride inclusions, allows the calculation of the response of the hydrided cladding under various loading scenarios. The model treats the Zry4 matrix material as J2 elastoplastic, and treats the hydrides as platelets oriented in predefined directions (e.g., circumferentially and radially). The model is hosted by the Albany analysis framework, where a finite element approximation of the weak form of the cladding boundary value problem is solved using a preconditioned Newton-Krylov approach. Instead of forming the required system Jacobian operator directly or approximating its action with a differencing operation, Albany leverages the Trilinos Sacado package to form the Jacobian via automatic differentiation. We present results that describe the performance of the model in comparison with as-fabricated Zry4 as well as HB Robinson fuel cladding. Further, we also present performance results that demonstrate the efficacy of the overall solution method employed to host the model.

  12. Amniotic Membrane Grafts for the Prevention of Esophageal Stricture after Circumferential Endoscopic Submucosal Dissection

    PubMed Central

    Barret, Maximilien; Pratico, Carlos Alberto; Camus, Marine; Beuvon, Frédéric; Jarraya, Mohamed; Nicco, Carole; Mangialavori, Luigi; Chaussade, Stanislas; Batteux, Frédéric; Prat, Frédéric

    2014-01-01

    Background and Aims The prevention of esophageal strictures following circumferential mucosal resection remains a major clinical challenge. Human amniotic membrane (AM) is an easily available material, which is widely used in ophthalmology due to its wound healing, anti-inflammatory and anti-fibrotic properties. We studied the effect of AM grafts in the prevention of esophageal stricture after endoscopic submucosal dissection (ESD) in a swine model. Animals and Methods In this prospective, randomized controlled trial, 20 swine underwent a 5 cm-long circumferential ESD of the lower esophagus. In the AM Group (n = 10), amniotic membrane grafts were placed on esophageal stents; a subgroup of 5 swine (AM 1 group) was sacrificed on day 14, whereas the other 5 animals (AM 2 group) were kept alive. The esophageal stent (ES) group (n = 5) had ES placement alone after ESD. Another 5 animals served as a control group with only ESD. Results The prevalence of symptomatic strictures at day 14 was significantly reduced in the AM group and ES groups vs. the control group (33%, 40% and 100%, respectively, p = 0.03); mean esophageal diameter was 5.8±3.6 mm, 6.8±3.3 mm, and 2.6±1.7 mm for AM, ES, and control groups, respectively. Median (range) esophageal fibrosis thickness was 0.87 mm (0.78–1.72), 1.19 mm (0.28–1.95), and 1.65 mm (0.7–1.79) for AM 1, ES, and control groups, respectively. All animals had developed esophageal strictures by day 35. Conclusions The anti-fibrotic effect of AM on esophageal wound healing after ESD delayed the development of esophageal stricture in our model. However, this benefit was of limited duration in the conditions of our study. PMID:24992335

  13. Circumferential Three-Dimensional-Printed Tracheal Grafts: Research Model Feasibility and Early Results.

    PubMed

    Bhora, Faiz Y; Lewis, Erik E; Rehmani, Sadiq S; Ayub, Adil; Raad, Wissam; Al-Ayoubi, Adnan M; Lebovics, Robert S

    2017-09-01

    Methods for tracheal graft research have presented persistent challenges to investigators, and three-dimensional (3D)-printed biosynthetic grafts offer one potential development platform. We aimed to develop an efficient research platform for customizable circumferential 3D-printed tracheal grafts and evaluate feasibility and early structural integrity with a large-animal model. Virtual 3D models of porcine subject tracheas were generated using preoperative computed tomography scans. Two designs were used to test graft customizability and the limits of the construction process. Designs I and II used 270-degree and 360-degree external polycaprolactone scaffolds, respectively, both encompassing a circumferential extracellular matrix collagen layer. The polycaprolactone scaffolds were made in a fused-deposition modeling 3D printer and customized to the recipient's anatomy. Design I was implanted in 3 pigs and design II in 2 pigs, replacing 4-ring tracheal segments. Data collected included details of graft construction, clinical outcomes, bronchoscopy, and gross and histologic examination. The 3D-printed biosynthetic grafts were produced with high fidelity to the native organ. The fabrication process took 36 hours. Grafts were implanted without immediate complication. Bronchoscopy immediately postoperatively and at 1 week demonstrated patent grafts and appropriate healing. All animals lived beyond a predetermined 1-week survival period. Bronchoscopy at 2 weeks showed significant paraanastomotic granulation tissue, which, along with partial paraanastomotic epithelialization, was confirmed on pathology. Overall survival was 17 to 34 days. We propose a rapid, reproducible, resource efficient method to develop various anatomically precise grafts. Further graft refinement and strategies for granulation tissue management are needed to improve outcomes. Copyright © 2017 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  14. The Extended Posterior Circumferential Decompression Technique in the Management of Tubercular Spondylitis with and without Paraplegia

    PubMed Central

    Rathinavelu, Barani; Krishnan, Venkatesh; Amritanand, Rohit; Sundararaj, Gabriel David

    2014-01-01

    Study Design Retrospective clinical series. Purpose To study the clinical, functional and radiological results of patients with tuberculous spondylitis with and without paraplegia, treated surgically using the "Extended Posterior Circumferential Decompression (EPCD)" technique. Overview of Literature With the increasing possibility of addressing all three columns by a single approach, posterior and posterolateral approaches are gaining acceptance. A single exposure for cases with neurological deficit and kyphotic deformity requiring circumferential decompression, anterior column reconstruction and posterior instrumentation is helpful. Methods Forty-one patients with dorsal/dorsolumbar/lumbar tubercular spondylitis who were operated using the EPCD approach between 2006 to 2009 were included. Postoperatively, patients were started on nine-month anti-tuberculous treatment. They were serially followed up to thirty-six months and both clinical measures (including pain, neurological status and ambulatory status) and radiological measures (including kyphotic angle correction, loss of correction and healing status) were used for assessment. Results Disease-healing with bony fusion (interbody fusion) was seen in 97.5% of cases. Average deformity (kyphosis) correction was 54.6% in dorsal spine and 207.3% in lumbar spine. Corresponding loss of correction was 3.6 degrees in dorsal spine and 1.9 degrees in the lumbar spine. Neurological recovery in Frankel B and C paraplegia was 85.7% and 62.5%, respectively. Conclusions The EPCD approach permits all the advantages of a single or dual session anterior and posterior surgery, with significant benefits in terms of decreased operative time, reduced hospital stay and better kyphotic angle correction. PMID:25558312

  15. Application of Circumferential Compression Device (Binder) in Pelvic Injuries: Room for Improvement

    PubMed Central

    Vaidya, Rahul; Roth, Matthew; Zarling, Bradley; Zhang, Sarah; Walsh, Christopher; Macsuga, Jessica; Swartz, John

    2016-01-01

    Introduction The use of a noninvasive pelvic circumferential compression device (PCCD) to achieve pelvic stabilization by both decreasing pelvic volume and limiting inter-fragmentary motion has become commonplace, and is a well-established component of Advanced Trauma Life Support (ATLS) protocol in the treatment of pelvic ring injuries. The purpose of this study was to evaluate the following: 1) how consistently a PCCD was placed on patients who arrived at our hospital with unstable pelvic ring injuries; 2) if they were placed in a timely manner; and 3) if hemodynamic instability influenced their use. Methods We performed an institutional review board-approved retrospective study on 112 consecutive unstable pelvic ring injuries, managed over a two-year period at our Level I trauma center. Our hospital electronic medical records were used to review EMT, physician, nurses’, operative notes and radiographic images, to obtain information on the injury and PCCD application. The injuries were classified by an orthopaedic trauma surgeon and a senior orthopaedic resident. Proper application of a pelvic binder using a sheet is demonstrated. Results Only 47% of unstable pelvic fractures received PCCD placement, despite being the standard of care according to ATLS. Lateral compression mechanism pelvic injuries received PCCDs in 33% of cases, while anterior posterior compression (APC) and vertical shear (VS) injuries had applications in 63% of cases. Most of these PCCD devices were applied after imaging (72%). Hemodynamic instability did not influence PCCD application. Conclusion PCCD placement was missed in many (37%) of APC and VS mechanism injuries, where their application could have been critical to providing stability. Furthermore, to provide rapid stability, pelvic circumferential compression devices should be applied after secondary examination, rather than after receiving imaging results. Better education on timing and technique of PCCD placement at our institution

  16. Successful treatment of cervical myelopathy with minimal morbidity by circumferential decompression and fusion

    PubMed Central

    Sanchez-Mejia, Rene O.; Ben-Haim, Sharona; Ames, Christopher P.

    2007-01-01

    Circumferential cervical decompression and fusion (CCDF) is an important technique for treating patients with severe cervical myelopathy. While circumferential cervical decompression and fusion may provide improved spinal cord decompression and stability compared to unilateral techniques, it is commonly associated with increased morbidity and mortality. We performed a retrospective analysis of patients undergoing CCDF at the University of California, San Francisco (UCSF) between January 2003 and December 2004. We identified 53 patients and reviewed their medical records to determine the effectiveness of CCDF for improving myelopathy, pain, and neurological function. Degree of fusion, functional anatomic alignment, and stability were also assessed. Operative morbidity and mortality were measured. The most common causes of cervical myelopathy, instability, or deformity were degenerative disease (57%) and traumatic injury (34%). Approximately one-fifth of patients had a prior fusion performed elsewhere and presented with fusion failure or adjacent-level degeneration. Postoperatively, all patients had stable (22.6%) or improved (77.4%) Nurick grades. The average preoperative and postoperative Nurick grades were 2.1 ± 1.9 and 0.4 ± 0.9, respectively. Pain improved in 85% of patients. All patients had radiographic evidence of fusion at last follow-up. The most common complication was transient dysphagia. Our average clinical follow-up was 27.5 ± 9.5 months. We present an extensive series of patients and demonstrate that cervical myelopathy can successfully be treated with CCDF with minimal operative morbidity. CCDF may provide more extensive decompression of the spinal cord and may be more structurally stable. Concerns regarding operation-associated morbidity should not strongly influence whether CCDF is performed. PMID:17216528

  17. Quantitation of extent, depth, and severity of planar thallium defects in patients undergoing exercise thallium-201 scintigraphy

    SciTech Connect

    Reisman, S.; Maddahi, J.; Van Train, K.; Garcia, E.; Berman, D.

    1986-08-01

    Previous quantitation of exercise-redistribution planar /sup 201/TI scintigraphy has shown high sensitivity and specificity in the detection of coronary artery disease and improved detection of individual coronary stenoses over visual analysis. By using similar methodology based on the circumferential profile method, we studied 133 patients to quantitatively assess the extent, depth, and severity of thallium defects compared with consensus visual analysis. These quantitative measurements are objective, requiring only three operator interactions. In comparing quantitative and visual results, a close correlation was found for measurement of extent of thallium defect (r = 0.73) and severity of defect (r = 0.79). In detecting patients with the high-risk scintigraphic pattern of a severe stress thallium defect, a quantitative depth score of greater than or equal to 36 had an 81% sensitivity and an 82% specificity. Thus, this nearly automatic, computerized quantitative method allows objective determination of extent, severity, and depth of planar /sup 201/TI defects.

  18. Loss of endothelial KATP channel-dependent, NO-mediated dilation of endocardial resistance coronary arteries in pigs with left ventricular hypertrophy.

    PubMed

    Gendron, Marie-Eve; Thorin, Eric; Perrault, Louis P

    2004-09-01

    The influence of left ventricular hypertrophy (LVH) on the endothelial function of resistance endocardial arteries is not well established. The aim of this study was to characterise the mechanisms responsible for UK-14,304 (alpha(2)-adrenoreceptor agonist)-induced endothelium-dependent dilation in pig endocardial arteries isolated from hearts with or without LVH. LVH was induced by aortic banding 2 months before determining endothelial function. Following euthanasia, hearts were harvested and endocardial resistance arteries were isolated and pressurised to 100 mmHg in no-flow conditions. Vessels were preconstricted with acetylcholine (ACh) or high external K(+) (40 mmol l(-1) KCl). Results are expressed as mean+/-s.e.m. UK-14,304 induced a maximal dilation representing 79+/-6% (n=8) of the maximal diameter. NO synthase (l-NNA, 10 micromol l(-1), n=7) or guanylate cyclase (ODQ, 10 micromol l(-1), n=4) inhibition reduced (P<0.05) UK-14,304-dependent dilation to 35+/-6 and 18+/-7%, respectively. Apamin and charybdotoxin reduced (P<0.05) to 39+/-8% (n=4) the dilation induced by UK-14,304. In depolarised conditions, however, this dilation was prevented (P<0.05). UK-14,304-induced dilation was reduced (P<0.05) by glibenclamide (Glib, 1 micromol l(-1)), a K(ATP) channel blocker, either alone (35+/-10%, n=5) or in combination with l-NNA (34+/-9%, n=4). In LVH, UK-14,304-induced maximal dilation was markedly reduced (25+/-4%, P<0.05) compared to control; it was insensitive to l-NNA (21+/-5%) but prevented either by the combination of l-NNA, apamin and charybdotoxin, or by 40 mmol l(-1) KCl. Activation of endothelial alpha(2)-adrenoreceptor induces an endothelium-dependent dilation of pig endocardial resistance arteries. This dilation is in part dependent on NO, the release of which appears to be dependent on the activation of endothelial K(ATP) channels. This mechanism is blunted in LVH, leading to a profound reduction in UK-14,304-dependent dilation.

  19. Role of collateral blood flow in the apparent disparity between the extent of abnormal wall thickening and perfusion defect size during acute myocardial infarction and demand ischemia.

    PubMed

    Leong-Poi, Howard; Coggins, Matthew P; Sklenar, Jiri; Jayaweera, Ananda R; Wang, Xin-Qun; Kaul, Sanjiv

    2005-02-15

    The aim of this study was to test the hypothesis that the apparent disparity between the circumferential extent of abnormal wall thickening (WT) and that of infarct size (IS) at rest or size of ischemic zone (IZ) during demand ischemia (DI) is principally due to the effects of collateral blood flow (CollBF). A disparity has been reported between the circumferential extent of abnormal WT and that of IS at rest or IZ size during DI. Wall thickening and CollBF were measured in 18 dogs: at 6 h after coronary occlusion (Group 1, n = 6), and during 40 microg x kg x min(-1) of dobutamine in the presence of either one-vessel (Group 2, n = 6) or two-vessel stenosis (Group 3, n = 6). The apparent overestimation of the IS by the circumferential extent of abnormal WT was due to intermediate levels of CollBF in border zones within the risk area that had escaped necrosis. Although reduced, WT in these regions was commensurate with the level of flow. Similarly, during DI, regions within the IZ exhibiting the worst WT in Group 2 and 3 dogs were those not supplied by CollBF. The regions supplied by CollBF had intermediate WT, which was also commensurate with the level of flow. Only in two Group 3 dogs was tethering seen in small, normally perfused regions that were interspersed between two large IZ. Excluding these few tethered regions, data from different myocardial regions (infarcted, ischemic, CollBF dependent, and normal) were described by a single relation: y = 57(1 - e([-0.72(x - 0.06)])) (r = 0.80, p < 0.001). Myocardial regions at the margins of ischemic territories contribute to the apparent disparity between the circumferential extent of abnormal WT and IS or IZ during DI. In most circumstances, these regions are supplied by collaterals and their WT is commensurate with the degree of myocardial blood flow. The apparent disparity between the circumferential extent of WT and ischemia is rarely due to myocardial tethering, which is seen only in some instances of multi

  20. Self-acting lift-pad geometry for circumferential seals: A noncontacting concept. [performance tests on hydrodynamic seals

    NASA Technical Reports Server (NTRS)

    Allen, G. P.

    1980-01-01

    A segmented circumferential seal with lift pads for hydrodynamic action was analyzed over ranges of speed and sealed pressure. Performance predictions, which predicted noncontact operation for speeds as high as 600 revolutions per second at sealed pressures to 86 N/sq cm, are discussed. Performance tests were performed on the seals and compared with the performance predictions.

  1. Circumferential electrocautery of the patella in primary total knee replacement without patellar replacement: a meta-analysis and systematic review

    NASA Astrophysics Data System (ADS)

    Fan, Lihong; Ge, Zhaogang; Zhang, Chen; Li, Jia; Yu, Zefeng; Dang, Xiaoqian; Wang, Kunzheng

    2015-03-01

    The purpose of this meta-analysis and systematic review was to identify and assess whether circumferential electrocautery is useful for improving outcomes after primary total knee replacement(TKR). We searched MEDLINE, EMBASE, PubMed, SpringerLink, Web of Knowledge, OVID CINAHL, OVID EBM and Google Scholar and included articles published through January 2014. A total of 6 articles met the inclusion criteria. Of the 776 cases included in the analysis, 388 cases involved patellar denervation, and 388 cases were designated as the control group. The meta-analysis revealed no significant difference in the incidence of anterior knee pain (AKP, p = 0.18) or in the visual analogue scale score (VAS, p = 0.23) between the two groups. In addition, AKSS Function Score indicated no significant difference between the two groups (p = 0.28). However, the OKS (p = 0.02), patellar score (p = 0.01), AKSS-Knee Score (p = 0.004), range of motion (ROM, p < 0.0001) and WOMAC Score (p = 0.0003) indicated that circumpatellarelectrocautery improved clinical outcomes compared with non-electrocautery. The results indicate that circumferential electrocautery of the patella does not significantly improve AKP compared with non-electrocautery techniques but that circumferential electrocautery significantly improves patients' knee function after surgery. Therefore, we believe that circumferential electrocautery is beneficial to the outcome of primary TKR surgery without patellar replacement.

  2. Circumferentially segmented duct lines optimized for axisymmetric and standing wave sources. [reducing noise from turbofan engines galerkin method acoustic attenuation

    NASA Technical Reports Server (NTRS)

    Watson, W. R.

    1982-01-01

    Optimum and off-optimum properties of circumferentially segmented duct liners are compared with those of uniform liners to identify any potential benefits of circumferentially segmented liners. High- and low-order spinning-mode sources are considered in the study. The solution for the segmented liner is obtained by a multimodal expansion of the segmented-liner eigenmodes in terms of a series of hardwall duct models. The coefficients in the hard-wall series are obtained by using Galerkin's method. Results show that for some frequencies and duct lengths, circumferentially segmented liners scatter energy equally between a higher and lower order circumferential wave number. Studies for higher order spinning-mode sources show that an optimized segmented liner with a hard-wall/soft-wal admittance variation representing an optimum configuration gives better performance than an optimized uniform liner. Overall, the greatest benefit of the segmented liner over the uniform liner occurs under off-optimum conditions. The optimized segmented liner gives more effective broadband performance than the optimized uniform liner.

  3. High speed OH-PLIF measurement of self-excited circumferential instabilities in an annular combustion chamber

    NASA Astrophysics Data System (ADS)

    Worth, Nicholas; Dawson, James

    2012-11-01

    Self-excited thermo-acoustic instabilities are a significant issue in the development of lean burn gas turbine combustors. Such instabilities arise through coupling of the unsteady heat release and acoustic waves, which can propagate both longitudinally and circumferentially in annular combustor geometries. Although a large number of studies have investigated longitudinal fluctuations in single axisymmetric flames, it is currently uncertain whether these results can be used to emulate circumferential oscillations in annular geometry. Therefore, the aim of the current project is to investigate the flame dynamics in an annular model gas turbine combustor during self-excited circumferential oscillations. Pressure measurements are used to characterise the circumferential oscillations, with high-speed OH chemiluminescence and OH-PLIF used to capture the flame dynamics. The flame structure and dynamics are significantly affected by both the proximity of neighbouring flames and the excitation mode; with different responses observed for small and large separation distances, and standing and spinning modes. These observations indicate that results from single flame investigations may only be representative of self-excited flames in annular geometry under in a limited set of conditions.

  4. Numerical analysis of flow in a centrifugal compressor with circumferential grooves: influence of groove location and number on flow instability

    NASA Astrophysics Data System (ADS)

    Chen, X.; Qin, G.; Ai, Z.; Ji, Y.

    2017-08-01

    As an effective and economic method for flow range enhancement, circumferential groove casing treatment (CGCT) is widely used to increase the stall margin of compressors. Different from traditional grooved casing treatments, in which the grooves are always located over the rotor in both axial and radial compressors, one or several circumferential grooves are located along the shroud side of the diffuser passage in this paper. Numerical investigations were conducted to predict the performance of a low flow rate centrifugal compressor with CGCT in diffuser. Computational fluid dynamics (CFD) analysis is performed under stage environment in order to find the optimum location of the circumferential casing groove in consideration of stall margin enhancement and efficiency gain at design point, and the impact of groove number to the effect of this grooved casing treatment configuration in enhancing the stall margin of the compressor stage is studied. The results indicate that the centrifugal compressor with circumferential groove in vaned diffuser can obtain obvious improvement in the stall margin with sacrificing design efficiency a little. Efforts were made to study blade level flow mechanisms to determine how the CGCT impacts the compressor’s stall margin (SM) and performance. The flow structures in the passage, the tip gap, and the grooves as well as their mutual interactions were plotted and analysed.

  5. Circumferential electrocautery of the patella in primary total knee replacement without patellar replacement: a meta-analysis and systematic review.

    PubMed

    Fan, Lihong; Ge, Zhaogang; Zhang, Chen; Li, Jia; Yu, Zefeng; Dang, Xiaoqian; Wang, Kunzheng

    2015-03-24

    The purpose of this meta-analysis and systematic review was to identify and assess whether circumferential electrocautery is useful for improving outcomes after primary total knee replacement(TKR). We searched MEDLINE, EMBASE, PubMed, SpringerLink, Web of Knowledge, OVID CINAHL, OVID EBM and Google Scholar and included articles published through January 2014. A total of 6 articles met the inclusion criteria. Of the 776 cases included in the analysis, 388 cases involved patellar denervation, and 388 cases were designated as the control group. The meta-analysis revealed no significant difference in the incidence of anterior knee pain (AKP, p = 0.18) or in the visual analogue scale score (VAS, p = 0.23) between the two groups. In addition, AKSS Function Score indicated no significant difference between the two groups (p = 0.28). However, the OKS (p = 0.02), patellar score (p = 0.01), AKSS-Knee Score (p = 0.004), range of motion (ROM, p < 0.0001) and WOMAC Score (p = 0.0003) indicated that circumpatellarelectrocautery improved clinical outcomes compared with non-electrocautery. The results indicate that circumferential electrocautery of the patella does not significantly improve AKP compared with non-electrocautery techniques but that circumferential electrocautery significantly improves patients' knee function after surgery. Therefore, we believe that circumferential electrocautery is beneficial to the outcome of primary TKR surgery without patellar replacement.

  6. Circumferential electrocautery of the patella in primary total knee replacement without patellar replacement: a meta-analysis and systematic review

    PubMed Central

    Fan, Lihong; Ge, Zhaogang; Zhang, Chen; Li, Jia; Yu, Zefeng; Dang, Xiaoqian; Wang, Kunzheng

    2015-01-01

    The purpose of this meta-analysis and systematic review was to identify and assess whether circumferential electrocautery is useful for improving outcomes after primary total knee replacement(TKR). We searched MEDLINE, EMBASE, PubMed, SpringerLink, Web of Knowledge, OVID CINAHL, OVID EBM and Google Scholar and included articles published through January 2014. A total of 6 articles met the inclusion criteria. Of the 776 cases included in the analysis, 388 cases involved patellar denervation, and 388 cases were designated as the control group. The meta-analysis revealed no significant difference in the incidence of anterior knee pain (AKP, p = 0.18) or in the visual analogue scale score (VAS, p = 0.23) between the two groups. In addition, AKSS Function Score indicated no significant difference between the two groups (p = 0.28). However, the OKS (p = 0.02), patellar score (p = 0.01), AKSS-Knee Score (p = 0.004), range of motion (ROM, p < 0.0001) and WOMAC Score (p = 0.0003) indicated that circumpatellarelectrocautery improved clinical outcomes compared with non-electrocautery. The results indicate that circumferential electrocautery of the patella does not significantly improve AKP compared with non-electrocautery techniques but that circumferential electrocautery significantly improves patients' knee function after surgery. Therefore, we believe that circumferential electrocautery is beneficial to the outcome of primary TKR surgery without patellar replacement. PMID:25801456

  7. Puppy line, metaphyseal sclerosis, and caudolateral curvilinear and circumferential femoral head osteophytes in early detection of canine hip dysplasia.

    PubMed

    Risler, Amanda; Klauer, Julia M; Keuler, Nicholas S; Adams, William M

    2009-01-01

    Ventrodorsal extended hip radiographs were analyzed from Foxhounds, Irish setters, Greyhounds, and Labrador retrievers radiographed four to seven times between 8 and 110 weeks of age. Occurrence in these 91 dogs of a puppy line, an ill-defined zone of proximal femoral metaphyseal sclerosis, a femoral neck linear sclerosis, or circumferential linear femoral head osteophytosis at 15-17 weeks of age were compared with hip joint laxity, as measured by distraction index, and to later findings of caudal curvilinear femoral neck osteophytes, circumferential femoral head osteophytes, hip incongruity consistent with hip dysplasia and degenerative joint disease by 52 weeks of age. A puppy line and/or femoral metaphyseal sclerosis was common at 15-17 weeks of age for dogs at mimimal risk (Greyhounds) and high risk (Foxhounds) of developing early degenerative joint disease associated with canine hip dysplasia. Though 44% of Greyhound hips had puppy lines and 28% had femoral metaphyseal sclerosis at 15-17 weeks of age, no Greyhound had a caudolateral curvilinear osteophyte or circumferential femoral head osteophyte at 24-27 or 52 weeks of age. No significant relationship was found between occurrence of a puppy line, a circumferential femoral head osteophyte or femoral metaphyseal sclerosis at 15-17 weeks and canine hip dysplasia or degenerative joint disease incidence at 42-52 weeks. Presence of a caudolateral curvilinear osteophyte in at least one hip at 24-27 weeks was significantly related to the diagnosis of canine hip dysplasia by 42-52 weeks. When both a caudolateral curvilinear osteophyte and a circumferential femoral head osteophyte were present in a hip at 24-27 weeks, degenerative joint disease was evident in all such hips by 42-52 weeks of age.

  8. Non-invasive vascular radial/circumferential strain imaging and wall shear rate estimation using video images of diagnostic ultrasound.

    PubMed

    Wan, Jinjin; He, Fangli; Zhao, Yongfeng; Zhang, Hongmei; Zhou, Xiaodong; Wan, Mingxi

    2014-03-01

    The aim of this work was to develop a convenient method for radial/circumferential strain imaging and shear rate estimation that could be used as a supplement to the current routine screening for carotid atherosclerosis using video images of diagnostic ultrasound. A reflection model-based correction for gray-scale non-uniform distribution was applied to B-mode video images before strain estimation to improve the accuracy of radial/circumferential strain imaging when applied to vessel transverse cross sections. The incremental and cumulative radial/circumferential strain images can then be calculated based on the displacement field between consecutive B-mode images. Finally, the transverse Doppler spectra acquired at different depths along the vessel diameter were used to construct the spatially matched instantaneous wall shear values in a cardiac cycle. Vessel phantom simulation results revealed that the signal-to-noise ratio and contrast-to-noise ratio of the radial and circumferential strain images were increased by 2.8 and 5.9 dB and by 2.3 and 4.4 dB, respectively, after non-uniform correction. Preliminary results for 17 patients indicated that the accuracy of radial/circumferential strain images was improved in the lateral direction after non-uniform correction. The peak-to-peak value of incremental strain and the maximum cumulative strain for calcified plaques are evidently lower than those for other plaque types, and the echolucent plaques had higher values, on average, than the mixed plaques. Moreover, low oscillating wall shear rate values, found near the plaque and stenosis regions, are closely related to plaque formation. In conclusion, the method described can provide additional valuable results as a supplement to the current routine ultrasound examination for carotid atherosclerosis and, therefore, has significant potential as a feasible screening method for atherosclerosis diagnosis in the future. Copyright © 2014 World Federation for Ultrasound in

  9. Endocardial silicone lead wear: description of tribological phenomena on the basis of microscopic examination of removed leads. Preliminary report.

    PubMed

    Małecka, Barbara; Ząbek, Andrzej; Ciaś, Andrzej; Stępiński, Janusz; Kutarski, Andrzej; Rońda, Jacek; Lelakowski, Jacek; Małecki, Janusz

    2014-01-01

    The passage of a lead in tissues and in the cardiovascular system depends on the implantation technique. The structure of the leads, which is a combination of two or more materials, triggers their wear. Breakage of the external pacemaker (PM) lead insulation causes unsealing of the lead and exposure of its internal spaces, which can be the anchor of lead-dependent infective endocarditis (LDIE). In the case of implantable cardioverter-defibrillator (ICD) leads, damage to external insulation isthe cause of externalisation of the cable. To describe endocardial lead abrasion as a tribological phenomenon resulting from rubbing the leads against each other in the mechanism of polymer on polymer friction, and other mechanisms associated with lead structure i.e. polymer on metal friction. Twenty-two leads were extracted from ten patients (three women) aged 66.5 ± 13.4 years. In all cases, the reason for lead removal was infection — in 80% LDIE. The PM (one ICD) two- and three-lead systems, all with silicone insulation, were aged 3–25, mean 8.3 years. The destroyed polymer insulation was examined by optical and scanning electron microscopy. The site of damage was defined as the length of the lead from its distal end. This lead segment motion was analysed on chest scopy performed prior to the removal procedure. In this way, three sites of lead damage were distinguished: intracardiac, intravenous, and intrapocket. Tribological wear was observed on the polymer-metal interface and between the leads. The following characteristics were recorded: the type of PM or ICD system in which the extracted leads worked, the lead dwell time,and the lead model. Scanning electron examinations showed that in all cases lead insulation had undergone tribological failure. In all samples, the image of fatigue wear was recorded. In all examined places, we found evidence that adhesive wear was present with the transfer of material to the edges of friction zones and/or to friction partners. In

  10. Tumor-induced eosinophilia and endocardial fibrosis: evidence for ectopic eosinophilopoietin production and toxic O2 metabolite-mediated endothelial damage.

    PubMed

    Slungaard, A; Vercellotti, G; Zanjani, E; Ascensao, J; Jacob, H S

    1982-01-01

    We have described a patient with the clinical triad of anaplastic pulmonary carcinoma, extreme eosinophilia, and endocardial damage, with resulting fibrosis and mural "thrombosis." Since the "thrombi" consisted mainly of masses of aggregated eosinophils in close approximation to areas of fibrotic cardiac endothelium, it was hypothesized that eosinophils might provoke endothelial damage. Indeed, eosinophils generated large amounts of toxic oxygen species and were highly toxic to cultured endothelial cells in vitro; moreover, high concentrations of corticosteroids inhibited in tandem these phenomena. In addition, from the patient's tumor a 45,000-dalton "eosinophilopoietin" was extracted which stimulated eosinophil colonies without help from T-lymphocytes. We believe our results help explain both the hypereosinophilia which accompanies certain anaplastic carcinomas and the endocardial damage with thrombosis and embolization which may occur in any patient with excessive eosinophils. In this latter regard, our studies suggest that very high doses of corticosteroids--since they decrease generation of toxic oxygen products by, and the numbers of, eosinophils--may be rational therapy in hypereosinophilic syndromes.

  11. Comparison of treadmill exercise stress cardiac MRI to stress echocardiography in healthy volunteers for adequacy of left ventricular endocardial wall visualization: A pilot study.

    PubMed

    Thavendiranathan, Paaladinesh; Dickerson, Jennifer A; Scandling, Debbie; Balasubramanian, Vijay; Pennell, Michael L; Hinton, Alice; Raman, Subha V; Simonetti, Orlando P

    2014-05-01

    To compare exercise stress cardiac magnetic resonance (cardiac MR) to echocardiography in healthy volunteers with respect to adequacy of endocardial visualization and confidence of stress study interpretation. Twenty-eight healthy volunteers (age 28 ± 11 years, 15 males) underwent exercise stress echo and cardiac MR one week apart assigned randomly to one test first. Stress cardiac MR was performed using an MRI-compatible treadmill; stress echo was performed as per routine protocol. Cardiac MR and echo images were independently reviewed and scored for adequacy of endocardial visualization and confidence in interpretation of the stress study. Heart rate at the time of imaging was similar between the studies. Average time from cessation of exercise to start of imaging (21 vs. 31 s, P < 0.001) and time to acquire stress images (20 vs. 51 s, P < 0.001) was shorter for cardiac MR. The number of myocardial segments adequately visualized was significantly higher by cardiac MR at rest (99.8% vs. 96.4%, P = 0.002) and stress (99.8% vs. 94.1%, P = 0.001). The proportion of subjects in whom there was high confidence in the interpretation was higher for cardiac MR than echo (96% vs. 60%, P = 0.005). Exercise stress cardiac MR to assess peak exercise wall motion is feasible and can be performed at least as rapidly as stress echo. Copyright © 2013 Wiley Periodicals, Inc.

  12. Combined Right Ventricular Outflow Tract Epicardial and Endocardial Late Potential Ablation for Treatment of Brugada Storm: A Case Report and Review of the Literature.

    PubMed

    Saha, Sandeep A; Krishnan, Kousik; Madias, Christopher; Trohman, Richard G

    2016-12-01

    A 34-year-old man with Brugada syndrome (BrS) presented with electrical storm, manifested as multiple appropriate shocks from his implantable cardioverter-defibrillator over a period of 7 hours. He had not tolerated prior treatment with quinidine, and had self-discontinued cilostazol citing persistent palpitations. After stabilization with intravenous isoproterenol, an electrophysiology study was performed but no spontaneous or induced ventricular ectopic beats were identified. A three-dimensional (3D) endocardial electro-anatomic map of the right ventricular outflow tract (RVOT), pulmonic valve, and pulmonary artery, as well as a 3D epicardial map of the RVOT, were created. Low voltage, complex, fractionated electrograms and late potentials were targeted for irrigated radiofrequency ablation both endocardially and epicardially. Post-procedure, he was maintained on cilostazol (referring clinician preference), and has had no further ventricular tachyarrhythmia episodes over the past forty-one months. We propose that this novel ablation strategy may be useful for acute management of selected patients with BrS.

  13. Reduced residual conduction gaps and favourable outcome in contact force-guided circumferential pulmonary vein isolation.

    PubMed

    Itoh, Taihei; Kimura, Masaomi; Tomita, Hirofumi; Sasaki, Shingo; Owada, Shingen; Horiuchi, Daisuke; Sasaki, Kenichi; Ishida, Yuji; Kinjo, Takahiko; Okumura, Ken

    2016-04-01

    Although contact force (CF)-guided circumferential pulmonary vein isolation (CPVI) for paroxysmal atrial fibrillation (PAF) is useful, AF recurrence at long-term follow-up still remains to be resolved. The purpose of this study was to assess safety and efficacy of CF-guided CPVI and to compare residual conduction gaps during CPVI and long-term outcome between the conventional (non-CF-guided) and the CF-guided CPVI. We studied the 50 consecutive PAF patients undergoing CPVI by a ThermoCool EZ Steer catheter (conventional group, mean age 61 ± 10 years) and the other 50 consecutive PAF patients by a ThermoCool SmartTouch catheter (CF group, 65 ± 11 years). The procedure parameters and residual conduction gaps during CPVI, and long-term outcome for 12 months were compared between the two groups. Circumferential pulmonary vein isolation was successfully accomplished without any major complications in both groups. Total procedure and total fluoroscopy times were both significantly shorter in the CF group than in the conventional group (160 ± 30 vs. 245 ± 61 min, P < 0.001, and 17 ± 8 vs. 54 ± 27 min, P < 0.001, respectively). Total number of residual conduction gaps was significantly less in the CF group than in the conventional group (2.7 ± 1.7 vs. 6.3 ± 2.7, P < 0.05). The AF recurrence-free rates after CPVI during 12-month follow-up were 96% (48/50) in the CF group and 82% (41/50) in the conventional group (P = 0.02 by log rank test). Multivariate Cox regression analysis further supported this finding. Contact force-guided CPVI is safe and more effective in reducing not only the procedure time but also the AF recurrence than the conventional CPVI, possibly due to reduced residual conduction gaps during CPVI procedure. © The Author 2015. Published by Oxford University Press on behalf of the European Society of Cardiology.

  14. Endocardial cushion defect

    MedlinePlus

    ... Cyanosis . As the blood pressure increases in the lungs, blood starts to flow from the right side of ... include: Congestive heart failure Death Eisenmenger syndrome High blood pressure in the lungs Irreversible damage to the lungs Certain complications of ...

  15. Leak before break behaviour of austenitic and ferritic pipes containing circumferential defects

    SciTech Connect

    Stadtmueller, W.; Sturm, D.

    1997-04-01

    Several research projects carried out at MPA Stuttgart to investigate the Leak-before-Break (LBB) behavior of safety relevant pressure bearing components are summarized. Results presented relate to pipes containing circumferential defects subjected to internal pressure and external bending loading. An overview of the experimentally determined results for ferritic components is presented. For components containing postulated or actual defects, the dependence of the critical loading limit on the defect size is shown in the form of LBB curves. These are determined experimentally and/or by calculation for through-wall slits, and represent the boundary curve between leakage and massive fracture. For surface defects and a given bending moment and internal pressure, no fracture will occur if the length at leakage remains smaller than the critical defect length given by the LBB curve for through-wall defects. The predictive capability of engineering calculational methods are presented by way of example. The investigation programs currently underway, testing techniques, and initial results are outlined.

  16. Dispersion of circumferential waves in cylindrically anisotropic layered pipes in plane strain.

    PubMed

    Vasudeva, R Y; Sudheer, G; Vema, Anu Radha

    2008-06-01

    Dispersion spectra of circumferential waves along the periphery of circular pipes made of layered anisotropic materials do not seem to be available in literature. This note attempts to partially fill this gap by providing the dispersion spectra in two and three layered cylindrically anisotropic pipes in plane strain motion. The spectra for pipes executing time harmonic vibrations in plane strain condition are obtained as roots of a numerical characteristic equation derived extending a weighted residual method of solution of the governing equations for a single layer pipe [Towfighi et al., J. Appl. Mech. 69, 283-291 (2002)] to a general N layered pipe. The anisotropic elastic coefficients are considered to be independent of position coordinates and the bond condition at interfaces of the layers is assumed to be perfect. Numerical illustrations are presented for two and three layered pipes with anisotropy directions differing in adjacent layers. Increase in curvature of the pipe and inclination of the fiber orientation in the outermost layers to propagation direction are factors that seem to influence the mode number and pattern within the limited examples worked out.

  17. Vascular Repair by Circumferential Cell Therapy Using Magnetic Nanoparticles and Tailored Magnets.

    PubMed

    Vosen, Sarah; Rieck, Sarah; Heidsieck, Alexandra; Mykhaylyk, Olga; Zimmermann, Katrin; Bloch, Wilhelm; Eberbeck, Dietmar; Plank, Christian; Gleich, Bernhard; Pfeifer, Alexander; Fleischmann, Bernd K; Wenzel, Daniela

    2016-01-26

    Cardiovascular disease is often caused by endothelial cell (EC) dysfunction and atherosclerotic plaque formation at predilection sites. Also surgical procedures of plaque removal cause irreversible damage to the EC layer, inducing impairment of vascular function and restenosis. In the current study we have examined a potentially curative approach by radially symmetric re-endothelialization of vessels after their mechanical denudation. For this purpose a combination of nanotechnology with gene and cell therapy was applied to site-specifically re-endothelialize and restore vascular function. We have used complexes of lentiviral vectors and magnetic nanoparticles (MNPs) to overexpress the vasoprotective gene endothelial nitric oxide synthase (eNOS) in ECs. The MNP-loaded and eNOS-overexpressing cells were magnetic, and by magnetic fields they could be positioned at the vascular wall in a radially symmetric fashion even under flow conditions. We demonstrate that the treated vessels displayed enhanced eNOS expression and activity. Moreover, isometric force measurements revealed that EC replacement with eNOS-overexpressing cells restored endothelial function after vascular injury in eNOS(-/-) mice ex and in vivo. Thus, the combination of MNP-based gene and cell therapy with custom-made magnetic fields enables circumferential re-endothelialization of vessels and improvement of vascular function.

  18. Technical refinement in the management of circumferentially avulsed skin of the leg.

    PubMed

    Jeng, S F; Wei, F C

    1997-11-01

    Between 1989 and 1994, 42 patients with circumferential skin avulsion of lower extremities were treated with full-thickness skin graft from defatted avulsed flap. Among them, 39 patients were run over by rubber tires during car accidents; the remaining 3 patients were victims of industrial accidents by roller machines. The full-thickness skin grafts were prepared from the avulsed skin flap in attachment to avoid junctional hypertrophic scarring. They were then secured with multiple skin staples to their anatomical position to improve skin graft take. Initial take of graft averaged 91 percent (ranged from 75 percent to 100 percent). Twelve patients underwent secondary overgrafting after tangential excision of non-viable skin graft. Follow-up averaging 2.6 years revealed stable wounds in most of the patients. Ten patients experienced occasional breakdown of skin graft in the patella and popliteal fossa, which was treated conservatively. Except for five who had deformed contours of the leg due to muscle transfers, the patients were satisfied with the cosmetic appearance of their legs. Compared with conventional methods, this approach provided better appearance and less contracture.

  19. Numerical prediction of flow and heat transfer in a tube with circumferential fins and circular disks

    SciTech Connect

    Jeon, K.; Seo, T.; Lee, C.; Kim, C.

    1999-07-01

    The characteristics of fluid flow and heat transfer were numerically analyzed for hydrodynamically and thermally developing laminar flow in a tube with circumferential fins and circular disks. Computations were carried out for a variety of flow conditions and geometric arrangements for the fins and disks, and the effects of these on heat transfer enhancement and pressure drop were studied. In order to quantify the heat transfer enhancement effects of the fins and disks in a tube, the Nusselt numbers for various configurations were compared to those for a corresponding smooth tube. In addition, the flow pattern and the local Nusselt number of developing flow as well as the overall Nusselt numbers for both developing and fully developed flows were presented with associated increase in pressure drop. It was found that the flow was fully developed after passing two consecutive fins from the entrance, and that not only heat transfer enhancement but also pressure drop increase were significant with the fins and disks. And, it was known that heat transfer enhancement and pressure drop increase are strongly dependent on Reynolds number and the fin height rather than the size of the disk.

  20. A circular inclusion with circumferentially inhomogeneous imperfect interface in harmonic materials

    NASA Astrophysics Data System (ADS)

    McArthur, D. R.; Sudak, L. J.

    2016-03-01

    In the following analysis, we present a rigorous solution for the problem of a circular elastic inclusion surrounded by an infinite elastic matrix in finite plane elastostatics. The inclusion and matrix are separated by a circumferentially inhomogeneous imperfect interface characterized by the linear spring-type imperfect interface model where the interface is such that the same degree of imperfection is realized in both the normal and tangential directions. Through the use of analytic continuation, a set of first-order coupled ordinary differential equations with variable coefficients are developed for two analytic potential functions. The unknown coefficients of the potential functions are determined from their analyticity requirements and some additional problem-specific constraints. An example is then presented for a specific class of interface where the inclusion mean stress is contrasted between the homogeneous interface and inhomogeneous interface models. It is shown that, for circumstances where a homogeneously imperfect interface may not be warranted, the inhomogeneous model has a pronounced effect on the mean stress within the inclusion.

  1. Magnetic resonance imaging cannot predict histological tumour involvement of a circumferential surgical margin in rectal cancer.

    PubMed

    Dent, O F; Chapuis, P H; Haboubi, N; Bokey, L

    2011-09-01

    Several recent studies have attempted to evaluate the accuracy of preoperative magnetic resonance imaging (MRI) in predicting the likelihood of tumour involvement of the postoperative circumferential resection margin (CRM) in rectal cancer with the intention of selecting patients who might benefit from neoadjuvant therapy and as a guide to surgery. The aim of this study was to assess whether such studies can provide a valid answer as to whether preoperative MRI can accurately predict CRM involvement by tumour. The study design and methodology of studies on this topic were critically examined. Features identified as affecting the efficacy of these studies were: representativeness of patients, definition of the margin assessed by MRI and by histology, lack of blinding of surgeons and pathologists to MRI results, effect of neoadjuvant treatment, and number of patients studied. Because of methodological inadequacies in studies completed to date, there is insufficient evidence of the ability of a positive MRI result to predict an involved CRM. Although MRI may be able to identify a tumour that has extended to the mesorectal fascia and/or intersphincteric plane, logically, it cannot indicate where the surgical boundary of the resection will ultimately lie, and therefore cannot validly predict an involved CRM and should not be relied upon for this purpose. © 2011 The Authors. Colorectal Disease © 2011 The Association of Coloproctology of Great Britain and Ireland.

  2. Comparison of Endoscopic Mucosal Resection With Circumferential Incision and Endoscopic Submucosal Dissection for Rectal Carcinoid Tumor.

    PubMed

    Chen, Ru; Liu, Xiang; Sun, Siyu; Wang, Sheng; Ge, Nan; Wang, Guoxin; Guo, Jintao

    2016-06-01

    Endoscopic submucosal dissection (ESD) has been a valuable treatment of choice for rectal carcinoid tumors that are endoscopically treatable because of its satisfactory resection rate and low recurrence rate. For treatment of small rectal carcinoids, endoscopic mucosal resection (EMR) is more often chosen by endoscopists because of its safety and time efficiency. We applied circumferential incision and endoscopic mucosal resection (CI-EMR), which is a modification of EMR, to treat rectal carcinoid tumors and compared their efficacy and safety. Between January 2008 and December 2013, we enrolled 66 patients (30 in the ESD group and 36 in the CI-EMR group) at Shengjing Hospital who were pathologically diagnosed with rectal carcinoid tumors <15 mm in diameter. We retrospectively analyzed en bloc resection rates, pathologic complete resection rates, incidences of complications, follow-up outcomes, and procedure times. The en bloc resection rate and the histologic complete resection rate were similar, but the procedure time was longer in the ESD group than in the CI-EMR group. In cases that were incompletely resected, neither local recurrence nor distant metastasis was detected during follow-up. Similarly minor bleeding occurred in both groups, and no perforation occurred after either procedure. CI-EMR showed comparable en bloc resection and histologically complete resection rates and is technically simpler and minimally invasive compared with ESD. Because of its easier performance and shorter procedure time, CI-EMR may be preferable to ESD for resection of rectal carcinoid tumors <15 mm in diameter without invasion or distant metastases.

  3. Modeling and numerical investigation of the inlet circumferential fluctuations of swept and bowed blades

    NASA Astrophysics Data System (ADS)

    Tang, Mingzhi; Jin, Donghai; Gui, Xingmin

    2017-02-01

    The circumferential fluctuation (CF) source terms induced by the inviscid blade force can affect the inlet distribution of flow parameters and radial equilibrium of swept and bowed blades. However, these phenomena cannot be adequately described by throughflow methods based on the axisymmetric assumption. A transport model for the CF stresses is proposed and correlated to the distribution of circulation to reflect the effect of the inviscid blade force. To investigate the effect of the inlet CFs on swept and bowed blades, the model is integrated into a throughflow model and applied to a series of cascades with different sweep and bow angles. For swept cascades, the CF source terms change the distributions of incidence angles, as well as the radial equilibrium at the inlet of the blade passage. And the influence is enhanced as the absolute value of the sweep angle increases. For bowed cascades, the distributions of incidence angles are also altered. For both cases, the model can offer a good prediction of the inlet CF source terms, and prove to exert a better prediction of blade design key parameters such as flow angles.

  4. Feasibility of radial and circumferential strain analysis using 2D speckle tracking echocardiography in cats

    PubMed Central

    TAKANO, Hiroshi; ISOGAI, Tomomi; AOKI, Takuma; WAKAO, Yoshito; FUJII, Yoko

    2014-01-01

    The purpose of the present study is to investigate the feasibility of strain analysis using speckle tracking echocardiography (STE) in cats and to evaluate STE variables in cats with hypertrophic cardiomyopathy (HCM). Sixteen clinically healthy cats and 17 cats with HCM were used. Radial and circumferential strain and strain rate variables in healthy cats were measured using STE to assess the feasibility. Comparisons of global strain and strain variables between healthy cats and cats with HCM were performed. Segmental assessments of left ventricle (LV) wall for strain and strain rate variables in cats with HCM were also performed. As a result, technically adequate images were obtained in 97.6% of the segments for STE analysis. Sedation using buprenorphine and acepromazine did not affect any global strain nor strain rate variable. In LV segments of cats with HCM, reduced segmental radial strain and strain rate variables had significantly related with segmental LV hypertrophy. It is concluded that STE analysis using short axis images of LV appeared to be clinically feasible in cats, having the possibility to be useful for detecting myocardial dysfunctions in cats with diseased heart. PMID:25373881

  5. Feasibility of radial and circumferential strain analysis using 2D speckle tracking echocardiography in cats.

    PubMed

    Takano, Hiroshi; Isogai, Tomomi; Aoki, Takuma; Wakao, Yoshito; Fujii, Yoko

    2015-02-01

    The purpose of the present study is to investigate the feasibility of strain analysis using speckle tracking echocardiography (STE) in cats and to evaluate STE variables in cats with hypertrophic cardiomyopathy (HCM). Sixteen clinically healthy cats and 17 cats with HCM were used. Radial and circumferential strain and strain rate variables in healthy cats were measured using STE to assess the feasibility. Comparisons of global strain and strain variables between healthy cats and cats with HCM were performed. Segmental assessments of left ventricle (LV) wall for strain and strain rate variables in cats with HCM were also performed. As a result, technically adequate images were obtained in 97.6% of the segments for STE analysis. Sedation using buprenorphine and acepromazine did not affect any global strain nor strain rate variable. In LV segments of cats with HCM, reduced segmental radial strain and strain rate variables had significantly related with segmental LV hypertrophy. It is concluded that STE analysis using short axis images of LV appeared to be clinically feasible in cats, having the possibility to be useful for detecting myocardial dysfunctions in cats with diseased heart.

  6. Probabilistic elastic-plastic fracture analysis of circumferentially cracked pipes with finite-length surface flaws

    SciTech Connect

    Rahman, S.

    1996-12-01

    A new probabilistic model was developed for predicting elastic-plastic fracture response of circumferentially cracked pipes with finite-length, constant-depth, internal surface flaws subject to remote bending loads. It involves engineering estimation of energy release rate, J-tearing theory for characterizing ductile fracture, and standard methods of structural reliability theory. The underlying J-estimation model is based on deformation theory of plasticity, constitutive law characterized by power law model for stress-strain curve, and an equivalence criterion incorporating reduced thickness analogy for simulating system compliance due to the presence of a crack. New equations were developed to predict J-integral and were evaluated by comparing with available finite-element results from the current literature. Both analytical and simulation methods were formulated to determine the probabilistic characteristics of J. The same methods were used later to predict the probability of crack initiation and net-section collapse as a function of the applied load. Numerical examples are provided to illustrate the proposed methodology.

  7. Circumferential resection margin positivity after preoperative chemoradiotherapy based on magnetic resonance imaging for locally advanced rectal cancer: implication of boost radiotherapy to the involved mesorectal fascia

    PubMed Central

    Kim, Kyung Hwan; Park, Min Jung; Lim, Joon Seok; Kim, Nam Kyu; Min, Byung Soh; Ahn, Joong Bae; Kim, Tae Il; Kim, Ho Geun; Koom, Woong Sub

    2016-01-01

    Objective To identify patients who are at a higher risk of pathologic circumferential resection margin involvement using preoperative magnetic resonance imaging. Methods Between October 2008 and November 2012, 165 patients with locally advanced rectal cancer (cT4 or cT3 with <2 mm distance from tumour to mesorectal fascia) who received preoperative chemoradiotherapy were analysed. The morphologic patterns on post-chemoradiotherapy magnetic resonance imaging were categorized into five patterns from Pattern A (most-likely negative pathologic circumferential resection margin) to Pattern E (most-likely positive pathologic circumferential resection margin). In addition, the location of mesorectal fascia involvement was classified as lateral, posterior and anterior. The diagnostic accuracy of the morphologic criteria was calculated using receiver operating characteristic curve analysis. Results Pathologic circumferential resection margin involvement was identified in 17 patients (10.3%). The diagnostic accuracy of predicting pathologic circumferential resection margin involvement was 0.73 using the five-scale magnetic resonance imaging pattern. The sensitivity, specificity, positive predictive value and negative predictive value for predicting pathologic circumferential resection margin involvement were 76.5, 65.5, 20.3 and 96.0%, respectively, when cut-off was set between Patterns C and D. On multivariate logistic regression, the magnetic resonance imaging patterns D and E (P= 0.005) and posterior or lateral mesorectal fascia involvement (P= 0.017) were independently associated with increased probability of pathologic circumferential resection margin involvement. The rate of pathologic circumferential resection margin involvement was 30.0% when the patient had Pattern D or E with posterior or lateral mesorectal fascia involvement. Conclusions Patients who are at a higher risk of pathologic circumferential resection margin involvement can be identified using preoperative

  8. Circumferential resection margin positivity after preoperative chemoradiotherapy based on magnetic resonance imaging for locally advanced rectal cancer: implication of boost radiotherapy to the involved mesorectal fascia.

    PubMed

    Kim, Kyung Hwan; Park, Min Jung; Lim, Joon Seok; Kim, Nam Kyu; Min, Byung Soh; Ahn, Joong Bae; Kim, Tae Il; Kim, Ho Geun; Koom, Woong Sub

    2016-04-01

    To identify patients who are at a higher risk of pathologic circumferential resection margin involvement using preoperative magnetic resonance imaging. Between October 2008 and November 2012, 165 patients with locally advanced rectal cancer (cT4 or cT3 with <2 mm distance from tumour to mesorectal fascia) who received preoperative chemoradiotherapy were analysed. The morphologic patterns on post-chemoradiotherapy magnetic resonance imaging were categorized into five patterns from Pattern A (most-likely negative pathologic circumferential resection margin) to Pattern E (most-likely positive pathologic circumferential resection margin). In addition, the location of mesorectal fascia involvement was classified as lateral, posterior and anterior. The diagnostic accuracy of the morphologic criteria was calculated using receiver operating characteristic curve analysis. Pathologic circumferential resection margin involvement was identified in 17 patients (10.3%). The diagnostic accuracy of predicting pathologic circumferential resection margin involvement was 0.73 using the five-scale magnetic resonance imaging pattern. The sensitivity, specificity, positive predictive value and negative predictive value for predicting pathologic circumferential resection margin involvement were 76.5, 65.5, 20.3 and 96.0%, respectively, when cut-off was set between Patterns C and D. On multivariate logistic regression, the magnetic resonance imaging patterns D and E (P= 0.005) and posterior or lateral mesorectal fascia involvement (P= 0.017) were independently associated with increased probability of pathologic circumferential resection margin involvement. The rate of pathologic circumferential resection margin involvement was 30.0% when the patient had Pattern D or E with posterior or lateral mesorectal fascia involvement. Patients who are at a higher risk of pathologic circumferential resection margin involvement can be identified using preoperative magnetic resonance imaging although

  9. 3D modeling of circumferential SH guided waves in pipeline for axial cracking detection in ILI tools.

    PubMed

    Wang, Shen; Huang, Songling; Zhao, Wei; Wei, Zheng

    2015-02-01

    In this paper, SH (shear horizontal) guided waves propagating in the circumferential direction of pipeline are modeled in 3 dimensions, with the aim for axial cracking detection implementation in ILI (in-line inspection) tools in mind. A theoretical formulation is given first, followed by an explanation about the 3D numerical modeling work. Displacement wave structures from the simulation and dispersion equation are compared to verify the effectiveness of the FEM package. Transverse slots along the axial direction are modeled to simulate axial cracking. Reflection and transmission coefficients curves are obtained to provide insight in using circumferential SH guided waves for quantitative testing of axial pipeline cracking. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Circumferential negative-pressure dressing (VAC) to bolster skin grafts in the reconstruction of the penile shaft and scrotum.

    PubMed

    Weinfeld, Adam Bryce; Kelley, Patrick; Yuksel, Eser; Tiwari, Pankaj; Hsu, Patrick; Choo, Joshua; Hollier, Larry H

    2005-02-01

    This paper presents 4 consecutive cases using negative-pressure dressings (VAC) to bolster skin grafts in male genital reconstruction. In this series reconstruction followed 1 case of tumor ablation and 3 cases of debridement of abscesses or Fornier's gangrene. The VAC was applied circumferentially to the penis to secure skin grafts either directly to the penile shaft or to facilitate skin grafting to the scrotum. Graft areas ranged from 75 to 250 cm. All cases resulted in successful genital wound coverage; minor complications are described. Three practical points are brought forth. First, the VAC facilitates skin grafting to the complex contour of male genitalia. Second, the VAC can be applied circumferentially to the penis without the need for perfusion monitoring or fears of avascular necrosis. Third, with the use of the VAC, bolster use can likely be discontinued as early as 72 hours with good graft adherence and survival.

  11. Measurement of circumferential Lamb waves using a line-focus poly(vinylidene fluoride) transducer and cross correlation waveform analysis.

    PubMed

    Lin, Chun-I; Lu, Yan; He, Cunfu; Song, Guorong; Lee, Yung-Chun

    2015-11-01

    This paper presents a method for measuring circumferential Lamb waves propagating on a cylindrically curved thin plate. The measurement is carried out using a wideband and line-focused poly(vinylidene fluoride) transducer along with a defocusing waveform measurement method. After synthesizing the acquired waveforms, interference patterns can be obtained and a cross correlation method is developed to accurately extract the wave velocity as a function of wave frequency. Using three stainless steel thin plates of different thicknesses (100, 150, and 300 μm) and a radius of curvature of 10 mm, dispersion curves for several fundamental and higher order modes of circumferential Lamb waves are simultaneously determined. Theoretical dispersion curves are also calculated and compared with their experimental counterparts. Very good agreements are observed, which concludes the measurement accuracy of this measurement method.

  12. Snare coupling of the pre-pectoral pacing lead delivery catheter to the femoral transseptal apparatus for endocardial cardiac resynchronization therapy : mid-term results.

    PubMed

    Patel, Mehul B; Worley, Seth J

    2013-04-01

    Limitations imposed by the coronary sinus venous anatomy triggered the transseptal approach for endocardial LV lead placement. The alignment of the interatrial septum (IAS) and its neighborhood anatomy does not favor transseptal puncture from the pre-pectoral area. Locating and advancing a pre-pectoral LV lead delivery catheter (PDC) through an opening created in the IAS via femoral transseptal puncture (FTP) is time consuming and technically difficult. We describe a method where the PDC is snare coupled to the femoral transseptal apparatus (FTA). When the FTA is advanced into the left atrium (LA) the coupled PDC follows. The catheter of a 25-mm loop snare kit is replaced with the PDC (SelectSite®). The snare loop is positioned in the right common iliac vein from the pre-pectoral access. The PDC is coupled to the FTA by advancing the transseptal apparatus through the open snare loop. After conventional FTP, the FTA is withdrawn back into the right atrium (RA) over an extra support wire positioned in the LA. The PDC with open snare loop is pulled over the FTA up to the RA. The PDC is advanced to close the snare loop on the extra support wire immediately distal to the tip of the dilator close to the puncture site. The PDC is deflected to align with the FTA. The snare coupled catheters are gently advanced across the IAS into the LA. The PDC is released from the FTA by advancing the snare and opening the loop; the snare is then removed from the PDC. The PDC is deflected and advanced into the left ventricle (LV). After positioning the 4.1 Fr lumen less LV lead, the PDC is sliced and removed. The PDC snare coupled to the FTA was advanced into the LA in all five patients, however, access was lost during catheter manipulation in the one right-sided case. Endocardial LV lead was successfully positioned in all five patients. Snare coupling the pre-pectoral SelectSite® catheter to the FTA is technically simple, reliable and a safe method for transseptal endocardial LV lead

  13. Traumatic elbow luxation in a free-ranging hedgehog (Erinaceus europaeus): surgical management using circumferential suture prostheses.

    PubMed

    Vallefuoco, Rosario; Pignon, Charly; Furst, Anna; Personne, Lauriane; Courreau, Jean-Francois; Moissonnier, Pierre

    2013-06-01

    A free-ranging adult female hedgehog (Erinaceus europaeus) was presented injured, presumably from vehicular trauma. Clinical and radiographic examination under general anesthesia revealed a lateral elbow luxation. Closed reduction was unsuccessful, so a surgical approach with circumferential suture prostheses was used to stabilize the elbow. Neither perioperative nor postoperative complications were recorded. The hedgehog regained good range of motion of the elbow and was fully able to run and to roll into a ball.

  14. Internal porosity of cast titanium removable partial dentures: influence of sprue direction and diameter on porosity in simplified circumferential clasps.

    PubMed

    Baltag, Ioana; Watanabe, Kouichi; Miyakawa, Osamu

    2005-06-01

    The behavior of molten titanium in molds of complicated shape is still insufficiently understood; consequently, definite spruing criteria are not yet available for titanium RPD frameworks. This study investigated the influence of sprue design on porosity in pressure-cast titanium circumferential clasps. The patterns of 90 circumferential clasps were sprued with three directions (0, 30 and 60 degrees , as measured between the sprue and the symmetry plane of the clasp assembly) and three sprue diameters (1.5, 2.0 and 2.5mm). CPTi was cast in a one-chamber pressure casting machine. Pore number and size were assessed on radiographs of the castings. Statistical analysis was done by two-way analysis of variance (ANOVA), followed by Fisher's PLSD post hoc test. The porosity in lingual arms increased significantly with increase of sprue diameter and sprue angle, while the porosity in minor connectors had an inversely proportional distribution. Very low porosity, uninfluenced by sprue design, was found in buccal arms. In conclusion, internal porosity in titanium circumferential clasp arms can be minimized through sprue design: the 0 degrees sprue direction produced the least porosity, while for the 30 and 60 degrees directions, 1.5mm diameter sprues produced lower porosity than 2.0 and 2.5mm diameter sprues. In this study, the lowest porosity in titanium circumferential clasp arms was obtained with sprues attached perpendicularly to the minor connectors, regardless of sprue diameter. Conventional sprue directions produced significantly higher porosity in clasp lingual arms, the amount of porosity increasing with sprue diameter.

  15. 27 CFR 16.2 - Territorial extent.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Territorial extent. 16.2 Section 16.2 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL ALCOHOLIC BEVERAGE HEALTH WARNING STATEMENT Scope § 16.2 Territorial extent...

  16. 27 CFR 16.2 - Territorial extent.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Territorial extent. 16.2 Section 16.2 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS ALCOHOLIC BEVERAGE HEALTH WARNING STATEMENT Scope § 16.2 Territorial extent...

  17. 27 CFR 16.2 - Territorial extent.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Territorial extent. 16.2 Section 16.2 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL ALCOHOLIC BEVERAGE HEALTH WARNING STATEMENT Scope § 16.2 Territorial extent...

  18. 27 CFR 16.2 - Territorial extent.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Territorial extent. 16.2 Section 16.2 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS ALCOHOLIC BEVERAGE HEALTH WARNING STATEMENT Scope § 16.2 Territorial extent...

  19. 27 CFR 16.2 - Territorial extent.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Territorial extent. 16.2 Section 16.2 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS ALCOHOLIC BEVERAGE HEALTH WARNING STATEMENT Scope § 16.2 Territorial extent...

  20. 27 CFR 8.2 - Territorial extent.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Territorial extent. 8.2 Section 8.2 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS EXCLUSIVE OUTLETS Scope of Regulations § 8.2 Territorial extent. This part...

  1. 30 CFR 721.11 - Extent.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Extent. 721.11 Section 721.11 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR INITIAL PROGRAM REGULATIONS FEDERAL INSPECTIONS § 721.11 Extent. The authorized representative of the Secretary shall conduct inspections of surface coal mining...

  2. 27 CFR 25.2 - Territorial extent.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Territorial extent. 25.2 Section 25.2 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS BEER Scope of Regulations § 25.2 Territorial extent. This part applies to...

  3. 27 CFR 4.2 - Territorial extent.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Territorial extent. 4.2 Section 4.2 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS LABELING AND ADVERTISING OF WINE Scope § 4.2 Territorial extent. This part...

  4. 27 CFR 25.2 - Territorial extent.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Territorial extent. 25.2 Section 25.2 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL BEER Scope of Regulations § 25.2 Territorial extent. This part applies to...

  5. 27 CFR 25.2 - Territorial extent.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Territorial extent. 25.2 Section 25.2 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS BEER Scope of Regulations § 25.2 Territorial extent. This part applies to...

  6. 27 CFR 25.2 - Territorial extent.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Territorial extent. 25.2 Section 25.2 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL BEER Scope of Regulations § 25.2 Territorial extent. This part applies to...

  7. 27 CFR 25.2 - Territorial extent.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Territorial extent. 25.2 Section 25.2 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS BEER Scope of Regulations § 25.2 Territorial extent. This part applies to...

  8. 27 CFR 4.2 - Territorial extent.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Territorial extent. 4.2 Section 4.2 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL LABELING AND ADVERTISING OF WINE Scope § 4.2 Territorial extent. This...

  9. 27 CFR 4.2 - Territorial extent.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Territorial extent. 4.2 Section 4.2 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS LABELING AND ADVERTISING OF WINE Scope § 4.2 Territorial extent. This...

  10. 27 CFR 4.2 - Territorial extent.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Territorial extent. 4.2 Section 4.2 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL LABELING AND ADVERTISING OF WINE Scope § 4.2 Territorial extent. This...

  11. 27 CFR 4.2 - Territorial extent.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Territorial extent. 4.2 Section 4.2 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS LABELING AND ADVERTISING OF WINE Scope § 4.2 Territorial extent. This...

  12. Comparison of treatment for 153 cases of circumferential facial paralysis by low-power laser and galvan acupuncture

    NASA Astrophysics Data System (ADS)

    Li, Hai-Ling; Zhuo, Qing-shan

    1993-03-01

    Seventy-six patients were treated by low power He-Ne laser irradiation on Yangbai, Sibai, and other related acupoints. The other 77 cases were treated by Galvan-acupuncture with infrared radiation on the same acupoints. There was little difference between the therapeutic effects of these two groups (P > 0.05). However, the laser group had a much shorter treatment time than the other group. According to the theory of traditional Chinese medicine, circumferential facial paralysis is caused by exposure to cold which blocks the channel of vital energy resulting in the damage of bodily function. Acupuncture and moxibustion on certain acupoints can warm up the channels and remove the stasis allowing vital energy to pass through their passages to regulate bodily functions. Laser can do the same effectively with much less time. The laser therapy also features painlessness, safeness, and is free of bacteria. Circumferential facial paralysis is a common disease, which is clinically treated by acupuncture with reliable results. However, acupuncture is not fit for children who are not cooperative and those patients who are afraid of the pain accompanied with acupuncture. So we applied low power laser irradiation in the treatment of circumferential facial paralysis starting in 1985. The results were favorable. And the treatment time was shortened. The treatment procedures are reported.

  13. Circumferential resection margin (CRM) positivity after MRI assessment and adjuvant treatment in 189 patients undergoing rectal cancer resection.

    PubMed

    Simpson, G S; Eardley, N; McNicol, F; Healey, P; Hughes, M; Rooney, P S

    2014-05-01

    The management of rectal cancer relies on accurate MRI staging. Multi-modal treatments can downstage rectal cancer prior to surgery and may have an effect on MRI accuracy. We aim to correlate the findings of MRI staging of rectal cancer with histological analysis, the effect of neoadjuvant therapy on this and the implications of circumferential resection margin (CRM) positivity following neoadjuvant therapy. An analysis of histological data and radiological staging of all cases of rectal cancer in a single centre between 2006 and 2011 were conducted. Two hundred forty-one patients had histologically proved rectal cancer during the study period. One hundred eighty-two patients underwent resection. Median age was 66.6 years, and male to female ratio was 13:5. R1 resection rate was 11.1%. MRI assessments of the circumferential resection margin in patients without neoadjuvant radiotherapy were 93.6 and 88.1% in patients who underwent neoadjuvant radiotherapy. Eighteen patients had predicted positive margins following chemoradiotherapy, of which 38.9% had an involved CRM on histological analysis. MRI assessment of the circumferential resection margin in rectal cancer is associated with high accuracy. Neoadjuvant chemoradiotherapy has a detrimental effect on this accuracy, although accuracy remains high. In the presence of persistently predicted positive margins, complete resection remains achievable but may necessitate a more radical approach to resection.

  14. A one-session circumferential reconstruction in thoracic and lumbar spine fractures using a small expandable cage.

    PubMed

    Mouchaty, H; Conti, R; Conti, P; Desogus, N; Maleci, A; Di Lorenzo, N

    2008-12-01

    Circumferential reconstruction of thoracic and lumbar vertebrae is most frequently performed in two sessions. The authors assessed feasibility, safety and results of a surgical technique in which the use of a small cage allows a less invasive strategy. In addition, since the authors perform urgent decompression in specific cases of spinal cord injury, feasibility of this technique in emergency was verified. In two Neurosurgical Departments, between May 2001 and May 2006, 62 patients with thoracic or lumbar fractures were operated on using this technique. X-rays were performed postoperatively and around 45 days from surgery. Three-dimension-computed tomography (3D-CT) scans were performed at 3, 6 and 12 months. Neurological evaluations were repeated at every outpatient visit. After screw insertion at the adjacent levels and traditional transpedicular circumferential decompression, further bone is removed to excavate a niche in the vertebral body and the contiguous discs are removed. The expandable cage, filled with bone fragments, is inserted horizontal or oblique laterally to the sac and applied vertical inside that niche and then expanded. The circumferential stabilization is completed with bone grafting and posterior instrumentation. 3D-CT scans showed sound fusion and no manifest correction loss. Nineteen patients improved at least one grade in the ASIA scale and 11 gained neuromeric levels. This technique, fairly undemanding and feasible also in emergency, proved to be safe and resistant. Two-year follow-up demonstrated thriving fusion and steady alignment. It is a valuable surgical therapy to selected cases of burst fracture.

  15. Automated circumferential construction of first-order aqueous humor outflow pathways using spectral-domain optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Huang, Alex S.; Belghith, Akram; Dastiridou, Anna; Chopra, Vikas; Zangwill, Linda M.; Weinreb, Robert N.

    2017-06-01

    The purpose was to create a three-dimensional (3-D) model of circumferential aqueous humor outflow (AHO) in a living human eye with an automated detection algorithm for Schlemm's canal (SC) and first-order collector channels (CC) applied to spectral-domain optical coherence tomography (SD-OCT). Anterior segment SD-OCT scans from a subject were acquired circumferentially around the limbus. A Bayesian Ridge method was used to approximate the location of the SC on infrared confocal laser scanning ophthalmoscopic images with a cross multiplication tool developed to initiate SC/CC detection automated through a fuzzy hidden Markov Chain approach. Automatic segmentation of SC and initial CC's was manually confirmed by two masked graders. Outflow pathways detected by the segmentation algorithm were reconstructed into a 3-D representation of AHO. Overall, only <1% of images (5114 total B-scans) were ungradable. Automatic segmentation algorithm performed well with SC detection 98.3% of the time and <0.1% false positive detection compared to expert grader consensus. CC was detected 84.2% of the time with 1.4% false positive detection. 3-D representation of AHO pathways demonstrated variably thicker and thinner SC with some clear CC roots. Circumferential (360 deg), automated, and validated AHO detection of angle structures in the living human eye with reconstruction was possible.

  16. Distinguishable circumferential inclined direction tilt sensor based on fiber Bragg grating with wide measuring range and high accuracy

    NASA Astrophysics Data System (ADS)

    Jiang, Shanchao; Wang, Jing; Sui, Qingmei

    2015-11-01

    One novel distinguishable circumferential inclined direction tilt sensor is demonstrated by incorporating two strain sensitivity fiber Bragg gratings (FBGs) with two orthogonal triangular cantilever beam and using one fiber Bragg grating (FBG) as temperature compensation element. According to spatial vector and space geometry, theory calculation model of the proposed FBG tilt sensor which can be used to obtain the azimuth and tile angle of the inclined direction is established. To obtain its measuring characteristics, calibration experiment on one prototype of the proposed FBG tilt sensor is carried out. After temperature sensitivity experiment data analysis, the proposed FBG tilt sensor exhibits excellent temperature compensation characteristics. In 2-D tilt angle experiment, tilt measurement sensitivities of these two strain sensitivity FBGs are 140.85°/nm and 101.01°/nm over a wide range of 60º. Further, azimuth and tile angle of the inclined direction can be obtained by the proposed FBG tilt sensor which is verified in circumferential angle experiment. Experiment data show that relative errors of azimuth are 0.55% (positive direction) and 1.14% (negative direction), respectively, and relative errors of tilt angle are all less than 3%. Experiment results confirm that the proposed distinguishable circumferential inclined direction tilt sensor based on FBG can achieve azimuth and tile angle measurement with wide measuring range and high accuracy.

  17. Defining a positive circumferential resection margin in oesophageal cancer and its implications for adjuvant treatment.

    PubMed

    O'Neill, J R; Stephens, N A; Save, V; Kamel, H M; Phillips, H A; Driscoll, P J; Paterson-Brown, S

    2013-07-01

    A positive circumferential resection margin (CRM) has been associated with a poorer prognosis in oesophageal and oesophagogastric junctional (OGJ) cancer. The College of American Pathologists defines the CRM as positive if tumour cells are present at the margin, whereas the Royal College of Pathologists also include tumour cells within 1 mm of this margin. The relevance of these differences is not clear and no study has investigated the impact of adjuvant therapy. The aim was to identify the optimal definition of an involved CRM in patients undergoing resection for oesophageal or OGJ cancer, and to determine whether adjuvant radiotherapy improved survival in patients with an involved CRM. This was a single-centre retrospective study of patients who had undergone attempted curative resection for a pathological T3 oesophageal or OGJ cancer. Clinicopathological variables and distance from the tumour to the CRM, measured to ± 0.1 mm, were correlated with survival. A total of 226 patients were included. Sex (P = 0·018), tumour differentiation (P = 0·019), lymph node status (P < 0·001), number of positive nodes (P < 0·001), and CRM distance (P = 0·042) were independently predictive of prognosis. No significant survival difference was observed between positive CRM 0-mm and 0·1-0·9-mm groups after controlling for other prognostic variables. Both groups had poorer survival than matched patients with a CRM at least 1 mm clear of tumour cells. Among patients with a positive CRM of less than 1 mm, those undergoing observation alone had a median survival of 18·6 months, whereas survival was a median of 10 months longer in patients undergoing adjuvant radiotherapy, but otherwise matched for prognostic variables (P = 0·009). A positive CRM of 1 mm or less should be regarded as involved. Adjuvant radiotherapy confers a significant survival benefit in selected patients with an involved CRM. © 2013 British Journal of Surgery Society Ltd. Published by John Wiley & Sons Ltd.

  18. The Interaction between Fluid Wall Shear Stress and Solid Circumferential Strain Affects Endothelial Gene Expression.

    PubMed

    Amaya, Ronny; Pierides, Alexis; Tarbell, John M

    2015-01-01

    Endothelial cells lining the walls of blood vessels are exposed simultaneously to wall shear stress (WSS) and circumferential stress (CS) that can be characterized by the temporal phase angle between WSS and CS (stress phase angle - SPA). Regions of the circulation with highly asynchronous hemodynamics (SPA close to -180°) such as coronary arteries are associated with the development of pathological conditions such as atherosclerosis and intimal hyperplasia whereas more synchronous regions (SPA closer to 0°) are spared of disease. The present study evaluates endothelial cell gene expression of 42 atherosclerosis-related genes under asynchronous hemodynamics (SPA=-180 °) and synchronous hemodynamics (SPA=0 °). This study used a novel bioreactor to investigate the cellular response of bovine aortic endothelial cells (BAECS) exposed to a combination of pulsatile WSS and CS at SPA=0 or SPA=-180. Using a PCR array of 42 genes, we determined that BAECS exposed to non-reversing sinusoidal WSS (10±10 dyne/cm2) and CS (4 ± 4%) over a 7 hour testing period displayed 17 genes that were up regulated by SPA = -180 °, most of them pro-atherogenic, including NFκB and other NFκB target genes. The up regulation of NFκB p50/p105 and p65 by SPA =-180° was confirmed by Western blots and immunofluorescence staining demonstrating the nuclear translocation of NFκB p50/p105 and p65. These data suggest that asynchronous hemodynamics (SPA=-180 °) can elicit proatherogenic responses in endothelial cells compared to synchronous hemodynamics without shear stress reversal, indicating that SPA may be an important parameter characterizing arterial susceptibility to disease.

  19. En bloc esophageal mucosectomy for concentric circumferential mucosal resection (with video).

    PubMed

    Willingham, Field F; Gee, Denise W; Sylla, Patricia; Lauwers, Gregory Y; Rattner, David W; Brugge, William R

    2009-01-01

    With conventional EMR, specimens are fragmented, metaplasia may be left behind, and invasive lesions could be missed because of incomplete sampling. Concentric subtotal esophageal mucosectomy would address these limitations. To examine en bloc esophageal mucosectomy (EEM). A prospective case series. An academic hospital. Nine swine. Conventional EMR was performed in the proximal esophagus. The submucosal space was entered, and the distal two thirds of the esophageal mucosa was freed with blunt dissection. A snare was threaded over the column of mucosa to the gastroesophageal junction. The column was resected, and the mucosa was retrieved. Clinical examination, follow-up endoscopy, necropsy, and gross and histopathologic examination. EEM permitted subtotal esophageal mucosectomy in 9 of 9 swine (tissue specimens removed ranged 9-15 cm in length). The mean procedure duration was 110 minutes. In the survival series, 4 of 4 swine thrived after surgery, for 9 to 13 days. At 9 days, there was no evidence of a perforation, stricture, or leak. At 13 days, 2 swine had a mild proximal stricture, which was easily traversed with a 9.8-mm gastroscope. On necropsy, the mediastinal and thoracic cavities were unremarkable in 3 of 4 swine. One swine was found to have a contained abscess containing cellulose, presumably secondary to ingestion of wood-chip bedding material postoperatively. Reepithelialization was present on histologic examination. An animal study. EEM is feasible and enabled concentric subtotal esophageal mucosal resection. The technique could completely and circumferentially excise intramucosal lesions. Longer follow-up and larger studies are needed to evaluate infection, stricture, and safety.

  20. Comparative analysis of glucagonergic cells, glia and the circumferential marginal zone in the reptilian retina

    PubMed Central

    Todd, Levi; Suarez, Lilianna; Squires, Natalie; Zelinka, Christopher Paul; Gribbins, Kevin; Fischer, Andy J.

    2015-01-01

    Retinal progenitors in the circumferential margin zone (CMZ) and Müller glia-derived progenitors have been well-described in the eyes of fish, amphibians and birds. However, there is no information regarding a CMZ and the nature of retinal glia in species phylogenetically bridging amphibians and birds. Thus, the purpose of this study was to examine the retinal glia and investigate whether a CMZ is present in the eyes of reptilian species. We used immuno-histochemical analyses to study retinal glia, neurons that could influence CMZ-progenitors, the retinal margin, and non-pigmented epithelium (NPE) of ciliary body of garter snakes, queen snakes, anole lizards, snapping turtles, and painted turtles. We compare our observations in reptile eyes to the CMZ and glia of fish, amphibians and birds. In all species, Sox9, Pax6 and the glucocorticoid receptor are expressed by Müller glia and cells at the retinal margin. However, proliferating cells were found only in the CMZ of turtles, but not in the eyes of anoles and snakes. Similar to eyes of chickens, the retinal margin in turtles contains accumulations of GLP1/glucagonergic neurites. We find that filamentous proteins, vimentin and GFAP, are expressed by Müller glia, but have different patterns of sub-cellular localization in the different species of reptiles. We provide evidence that the reptile retina may contain Non-astrocytic Inner Retinal Glial (NIRG) cells, similar to those described in the avian retina. We conclude that the retinal glia, glucagonergic neurons and CMZ of turtles appears to be the most similar to that of fish, amphibians and birds. PMID:26053997

  1. Measurement of the circumferential mechanical properties of the umbilical vein: experimental and numerical analyses.

    PubMed

    Karimi, Alireza; Navidbakhsh, Mahdi; Rezaee, Taraneh; Hassani, Kamran

    2015-01-01

    Coronary artery disease is responsible for almost 30% of all deaths worldwide. The saphenous vein and umbilical vein (UV) are the most common veins using for treatment as a coronary artery bypass graft (CABG). The mechanical properties of UV belonging to its long-term patency for CABG are very important. However, there is a lack of knowledge on the linear elastic and nonlinear hyperelastic mechanical properties of the UV. In this study, three stress definitions (second Piola-Kichhoff stress, engineering stress and true stress) and four strain definitions (Almansi-Hamel strain, Green-St Venant strain, engineering strain and true strain) are used to determine the elastic modulus, maximum stress and strain of eight human UVs under circumferential loading. The nonlinear mechanical behaviour of the UV is computationally investigated using Mooney-Rivlin hyperelastic model. A numerical finite element analysis is also carried out to simulate the constitutive modelling versus its numerical results. The results show that the Almansi-Hamel strain definition overestimates the elastic modulus while Green-St Venant strain definition underestimates the elastic modulus at different stress definitions. The true stress-true strain definition, which gives more accurate measurements of the tissue's response using the instantaneous values, reveals the Young's modulus and maximum stress of 2.18 and 6.01 MPa, respectively. The Mooney-Rivlin material model is well represented by the nonlinear mechanical behaviour of the UV. The findings of this study could have implications not only for understanding the extension and rupture mechanism of UV but also for interventions and surgeries, including balloon angioplasty, bypass and stenting.

  2. Measurement of the axial and circumferential mechanical properties of rat skin tissue at different anatomical locations.

    PubMed

    Karimi, Alireza; Haghighatnama, Maedeh; Navidbakhsh, Mahdi; Haghi, Afsaneh Motevalli

    2015-04-01

    Skin tissue is not only responsible for thermoregulation but also for protecting the human body from mechanical, bacterial, and viral insults. The mechanical properties of skin tissue may vary according to the anatomical locations in the body. However, the linear elastic and nonlinear hyperelastic mechanical properties of the skin in different anatomical regions and at different loading directions (axial and circumferential) so far have not been determined. In this study, the mechanical properties during tension of the rat abdomen and back were calculated at different loading directions using linear elastic and nonlinear hyperelastic material models. The skin samples were subjected to a series of tensile tests. The elastic modulus and maximum stress of the skin tissues were measured before the incidence of failure. The nonlinear mechanical behavior of the skin tissues was also computationally investigated through a constitutive equation. Hyperelastic strain energy density function was calibrated using the experimental data. The results revealed the anisotropic mechanical behavior of the abdomen and the isotropic mechanical response of the back skin. The highest elastic modulus was observed in the abdomen skin under the axial direction (10 MPa), while the lowest one was seen in the back skin under axial loading (5 MPa). The Mooney-Rivlin material model closely addressed the nonlinear mechanical behavior of the skin at different loading directions, which can be implemented in the future biomechanical models of skin tissue. The results might have implications not only for understanding of the isotropic and anisotropic mechanical behavior of skin tissue at different anatomical locations but also for providing more information for a diversity of disciplines, including dermatology, cosmetics industry, clinical decision making, and clinical intervention.

  3. Comparative analysis of glucagonergic cells, glia, and the circumferential marginal zone in the reptilian retina.

    PubMed

    Todd, Levi; Suarez, Lilianna; Squires, Natalie; Zelinka, Christopher Paul; Gribbins, Kevin; Fischer, Andy J

    2016-01-01

    Retinal progenitors in the circumferential marginal zone (CMZ) and Müller glia-derived progenitors have been well described for the eyes of fish, amphibians, and birds. However, there is no information regarding a CMZ and the nature of retinal glia in species phylogenetically bridging amphibians and birds. The purpose of this study was to examine the retinal glia and investigate whether a CMZ is present in the eyes of reptilian species. We used immunohistochemical analyses to study retinal glia, neurons that could influence CMZ progenitors, the retinal margin, and the nonpigmented epithelium of ciliary body of garter snakes, queen snakes, anole lizards, snapping turtles, and painted turtles. We compare our observations on reptile eyes to the CMZ and glia of fish, amphibians, and birds. In all species, Sox9, Pax6, and the glucocorticoid receptor are expressed by Müller glia and cells at the retinal margin. However, proliferating cells were found only in the CMZ of turtles and not in the eyes of anoles and snakes. Similar to eyes of chickens, the retinal margin in turtles contains accumulations of GLP1/glucagonergic neurites. We find that filamentous proteins, vimentin and GFAP, are expressed by Müller glia, but have different patterns of subcellular localization in the different species of reptiles. We provide evidence that the reptile retina may contain nonastrocytic inner retinal glial cells, similar to those described in the avian retina. We conclude that the retinal glia, glucagonergic neurons, and CMZ of turtles appear to be most similar to those of fish, amphibians, and birds.

  4. Computed tomography imaging to quantify the area of the endocardial subvalvular apparatus in hypertrophic cardiomyopathy - Relationship to outflow tract obstruction and symptoms.

    PubMed

    Tajima, Miyu; Iguchi, Nobuo; Utanohara, Yuko; Hiroi, Yukio; Mahara, Keitaro; Niwa, Tatsunori; Takayama, Morimasa; Sumiyoshi, Tetsuya; Tomoike, Hitonobu

    2016-01-01

    Abnormalities of the endocardial subvalvular apparatus (SVA), which includes the papillary muscles directly attached to the mitral leaflet and left ventricular apical-basal muscle bundles, are occasionally identified in hypertrophic cardiomyopathy (HCM). Their associations with left ventricular outflow tract (LVOT) obstruction are unknown. We retrospectively reviewed cardiac computed tomography image data sets of 107 consecutive patients with HCM [56 obstructive (HOCM) and 51 non-obstructive (HNOCM)] as well as 53 controls. We evaluated anomalies of the SVA, measured the cross-sectional area of the SVA at the level of the LVOT, and subsequently assessed its correlation with the LVOT pressure gradient with and without medication. The area of the SVA was greater in HOCM than in HNOCM patients and in the control group (2.5 ± 1.3 cm(2), 1.4 ± 0.8 cm(2), and 0.9 ± 0.6 cm(2), respectively; p < 0.0001). Anomalies in the SVA were more often observed in the HOCM group than in the HNOCM patients and controls (abnormal papillary muscles, 14%, 8%, and 0%, respectively; P = 0.010; LV apical-basal muscle bundles, 73%, 65%, and 45%, respectively; P = 0.0094). Among HOCM patients, logistic regression analysis demonstrated that an SVA area of 2.2 cm(2) was an independent risk factor of residual severe LVOT obstruction (≥50 mmHg) after medication (odds ratio, 10.1; 95% confidence interval, 2.05-49.80). An increased area of the endocardial subvalvular apparatus could be an independent risk factor for clinically relevant LVOT obstruction refractory to medication. Copyright © 2016 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.

  5. Biophysical parameters during radiofrequency catheter ablation of scar-mediated ventricular tachycardia: epicardial and endocardial applications via manual and magnetic navigation.

    PubMed

    Bourke, Tara; Buch, Eric; Mathuria, Nilesh; Michowitz, Yoav; Yu, Ricky; Mandapati, Ravi; Shivkumar, Kalyanam; Tung, Roderick

    2014-11-01

    There is a paucity of data on biophysical parameters during radiofrequency ablation of scar-mediated ventricular tachycardia (VT). Data were collected from consecutive patients undergoing VT ablation with open-irrigation. Complete data were available for 372 lesions in 21 patients. The frequency of biophysical parameter changes were: >10Ω reduction (80%), bipolar EGM reduction (69%), while loss of capture was uncommon (32%). Unipolar injury current was seen in 72% of radiofrequency applications. Both EGM reduction and impedance drop were seen in 57% and a change in all 3 parameters was seen in only 20% of lesions. Late potentials were eliminated in 33%, reduced/modified in 56%, and remained after ablation in 11%. Epicardial lesions exhibited an impedance drop (90% vs. 76%, P = 0.002) and loss of capture (46% vs. 27%, P < 0.001) more frequently than endocardial lesions. Lesions delivered manually exhibited a >10Ω impedance drop (83% vs. 71%, P = 0.02) and an EGM reduction (71% vs. 40%, P < 0.001) more frequently than lesions applied using magnetic navigation, although loss of capture, elimination of LPs, and a change in all 3 parameters were similarly observed. VT ablation is inefficient as the majority of radiofrequency lesions do not achieve more than one targeted biophysical parameter. Only one-third of RF applications targeted at LPs result in complete elimination. Epicardial ablation within scar may be more effective than endocardial lesions, and lesions applied manually may be more effective than lesions applied using magnetic navigation. New technologies directed at identifying and optimizing ablation effectiveness in scar are clinically warranted. © 2014 Wiley Periodicals, Inc.

  6. BIOPHYSICAL PARAMETERS DURING RADIOFREQUENCY CATHETER ABLATION OF SCAR-MEDIATED VENTRICULAR TACHYCARDIA: EPICARDIAL AND ENDOCARDIAL APPLICATIONS VIA MANUAL AND MAGNETIC NAVIGATION

    PubMed Central

    Bourke, Tara; Buch, Eric; Mathuria, Nilesh; Michowitz, Yoav; Yu, Ricky; Mandapati, Ravi; Shivkumar, Kalyanam; Tung, Roderick

    2014-01-01

    Background There is a paucity of data on biophysical parameters during radiofrequency ablation of scar-mediated ventricular tachycardia (VT). Methods and Results Data was collected from consecutive patients undergoing VT ablation with open-irrigation. Complete data was available for 372 lesions in 21 patients. The frequency of biophysical parameter changes were: >10Ω reduction (80%), bipolar EGM reduction (69%), while loss of capture was uncommon (32%). Unipolar injury current was seen in 72% of radiofrequency applications. Both EGM reduction and impedance drop were seen in 57% and a change in all 3 parameters was seen in only 20% of lesions. Late potentials were eliminated in 33%, reduced/modified in 56%, and remained after ablation in 11%. Epicardial lesions exhibited an impedance drop (90% vs 76%, p=0.002) and loss of capture (46% vs 27%, p<0.001) more frequently than endocardial lesions. Lesions delivered manually exhibited a >10Ω impedance drop (83% vs 71%, p=0.02) and an EGM reduction (71% vs 40%, p< 0.001) more frequently than lesions applied using magnetic navigation, although loss of capture, elimination of LPs, and a change in all 3 parameters were similarly observed. Conclusions VT ablation is inefficient as the majority of radiofrequency lesions do not achieve more than one targeted biophysical parameter. Only one-third of RF applications targeted at LPs result in complete elimination. Epicardial ablation within scar may be more effective than endocardial lesions and lesions applied manually may be more effective than lesions applied using magnetic navigation. New technologies directed at identifying and optimizing ablation effectiveness in scar are clinically warranted. PMID:24946895

  7. Validation of the Predicted Circumferential and Radial Mode Sound Power Levels in the Inlet and Exhaust Ducts of a Fan Ingesting Distorted Inflow

    NASA Technical Reports Server (NTRS)

    Koch, L. Danielle

    2012-01-01

    Fan inflow distortion tone noise has been studied computationally and experimentally. Data from two experiments in the NASA Glenn Advanced Noise Control Fan rig have been used to validate acoustic predictions. The inflow to the fan was distorted by cylindrical rods inserted radially into the inlet duct one rotor chord length upstream of the fan. The rods were arranged in both symmetric and asymmetric circumferential patterns. In-duct and farfield sound pressure level measurements were recorded. It was discovered that for positive circumferential modes, measured circumferential mode sound power levels in the exhaust duct were greater than those in the inlet duct and for negative circumferential modes, measured total circumferential mode sound power levels in the exhaust were less than those in the inlet. Predicted trends in overall sound power level were proven to be useful in identifying circumferentially asymmetric distortion patterns that reduce overall inlet distortion tone noise, as compared to symmetric arrangements of rods. Detailed comparisons between the measured and predicted radial mode sound power in the inlet and exhaust duct indicate limitations of the theory.

  8. 27 CFR 6.2 - Territorial extent.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Territorial extent. 6.2 Section 6.2 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS âTIED-HOUSEâ Scope of Regulations § 6.2 Territorial extent. This part applies to the several States of the United...

  9. Trend analysis of Arctic sea ice extent

    NASA Astrophysics Data System (ADS)

    Silva, M. E.; Barbosa, S. M.; Antunes, Luís; Rocha, Conceição

    2009-04-01

    The extent of Arctic sea ice is a fundamental parameter of Arctic climate variability. In the context of climate change, the area covered by ice in the Arctic is a particularly useful indicator of recent changes in the Arctic environment. Climate models are in near universal agreement that Arctic sea ice extent will decline through the 21st century as a consequence of global warming and many studies predict a ice free Arctic as soon as 2012. Time series of satellite passive microwave observations allow to assess the temporal changes in the extent of Arctic sea ice. Much of the analysis of the ice extent time series, as in most climate studies from observational data, have been focussed on the computation of deterministic linear trends by ordinary least squares. However, many different processes, including deterministic, unit root and long-range dependent processes can engender trend like features in a time series. Several parametric tests have been developed, mainly in econometrics, to discriminate between stationarity (no trend), deterministic trend and stochastic trends. Here, these tests are applied in the trend analysis of the sea ice extent time series available at National Snow and Ice Data Center. The parametric stationary tests, Augmented Dickey-Fuller (ADF), Phillips-Perron (PP) and the KPSS, do not support an overall deterministic trend in the time series of Arctic sea ice extent. Therefore, alternative parametrizations such as long-range dependence should be considered for characterising long-term Arctic sea ice variability.

  10. Milligan-Morgan hemorrhoidectomy with anal cushion suspension and partial internal sphincter resection for circumferential mixed hemorrhoids.

    PubMed

    Lu, Ming; Shi, Guang-Ying; Wang, Guo-Qiang; Wu, Yan; Liu, Yang; Wen, Hao

    2013-08-14

    To identify a more effective treatment protocol for circumferential mixed hemorrhoids. A total of 192 patients with circumferential mixed hemorrhoids were randomized into the treatment group, where they underwent Milligan-Morgan hemorrhoidectomy with anal cushion suspension and partial internal sphincter resection, or the control group, where traditional external dissection and internal ligation were performed. Postoperative recovery and complications were monitored. The time to wound healing was 12.96 ± 2.25 d in the treatment group shorter than 19.58 ± 2.71 d in the control group. Slight pain rate was 58.3% in the treatment group higher than 22.9% in the control group; moderate pain rate was 33.3% in the treatment group lower than 56.3% in the control group severe pain rate was 8.4% in the treatment group lower than 20.8% in the control group. No edema rate was 70.8% in the treatment group higher than 43.8% in the control group; mild local edema rate was 26% in the treatment group lower than 39.6% in the control group obvious local edema was 3.03% in the treatment group lower than 16.7% in the control group. No stenosis rate was 85.4% in the treatment group higher than 63.5% in the control group; moderate stenosis rate was 14.6% in the treatment group Lower than 27.1% in the control group severe anal stenosis rate was 0% in the treatment group lower than 9.4% in the control group. Milligan-Morgan hemorrhoidectomy with anal cushion suspension and partial internal sphincter resection is the optimal treatment for circumferential mixed hemorrhoids and can be widely applied in clinical settings.

  11. Milligan-Morgan hemorrhoidectomy with anal cushion suspension and partial internal sphincter resection for circumferential mixed hemorrhoids

    PubMed Central

    Lu, Ming; Shi, Guang-Ying; Wang, Guo-Qiang; Wu, Yan; Liu, Yang; Wen, Hao

    2013-01-01

    AIM: To identify a more effective treatment protocol for circumferential mixed hemorrhoids. METHODS: A total of 192 patients with circumferential mixed hemorrhoids were randomized into the treatment group, where they underwent Milligan-Morgan hemorrhoidectomy with anal cushion suspension and partial internal sphincter resection, or the control group, where traditional external dissection and internal ligation were performed. Postoperative recovery and complications were monitored. RESULTS: The time to wound healing was 12.96 ± 2.25 d in the treatment group shorter than 19.58 ± 2.71 d in the control group. Slight pain rate was 58.3% in the treatment group higher than 22.9% in the control group; moderate pain rate was 33.3% in the treatment group lower than 56.3% in the control group severe pain rate was 8.4% in the treatment group lower than 20.8% in the control group. No edema rate was 70.8% in the treatment group higher than 43.8% in the control group; mild local edema rate was 26% in the treatment group lower than 39.6% in the control group obvious local edema was 3.03% in the treatment group lower than 16.7% in the control group. No stenosis rate was 85.4% in the treatment group higher than 63.5% in the control group; moderate stenosis rate was 14.6% in the treatment group Lower than 27.1% in the control group severe anal stenosis rate was 0% in the treatment group lower than 9.4% in the control group. CONCLUSION: Milligan-Morgan hemorrhoidectomy with anal cushion suspension and partial internal sphincter resection is the optimal treatment for circumferential mixed hemorrhoids and can be widely applied in clinical settings. PMID:23946609

  12. CFD Study of the J2-X LOX Two-Bladed Inducer in the Presence of a Circumferential Groove

    NASA Technical Reports Server (NTRS)

    Coker, Robert; West, Jeff

    2011-01-01

    Results are presented of a computational fluid dynamics (CFD) study done in support of water flow experiments of the J-2X Oxidizer Turbopump (OTP) 2-bladed inducer with a circumferential groove that were conducted at Marshall Space Flight Center (MSFC). Sub-scale water flow testing results indicate that the circumferential groove greatly reduces synchronous cavitation and subsequent bearing loads at a minimal performance cost, but the energy reappears as high order cavitation (HOC) that spans a relatively large frequency range. Thus, HOC may have implications for the full-scale OTP inducer in terms of reduced structural margin at higher mode frequencies. Simulations using the LOCI-Stream CFD program were conducted in order to explore the root physical cause of the HOC. It was found that the axial recirculation pattern in the circumferential groove causes high-swirl fluid to interact with the nearly-axial incoming fluid just above the inducer blades. The high-shear interface between the fluids is Kelvin-Helmholtz unstable, resulting in trains of low pressure regions or 'pearls' forming near the upstream edge of the groove. When the pressure in these regions becomes low enough and they get cut by the blade leading edge, HOC is thought to occur. Although further work is required, the numerical models indicate that the root cause of HOC is hydrodynamic. That is, the pearls are always present, even when cavitation is not. Comparisons to ongoing water flow experiments will be discussed, as well as predictions for the full-scale OTP inducer.

  13. Noninvasive Measures of Ventricular-Arterial Coupling and Circumferential Strain Predict Cancer Therapeutics-Related Cardiac Dysfunction.

    PubMed

    Narayan, Hari K; French, Benjamin; Khan, Abigail M; Plappert, Theodore; Hyman, David; Bajulaiye, Akinyemi; Domchek, Susan; DeMichele, Angela; Clark, Amy; Matro, Jennifer; Bradbury, Angela; Fox, Kevin; Carver, Joseph R; Ky, Bonnie

    2016-10-01

    This study sought to determine the relationships between echocardiography-derived measures of myocardial mechanics and cancer therapeutics-related cardiac dysfunction (CTRCD). Doxorubicin and trastuzumab are highly effective breast cancer therapies, but have a substantial risk of CTRCD. There is a critical need for the early detection of patients at increased risk of toxicity. We performed a prospective, longitudinal cohort study of breast cancer participants undergoing doxorubicin and/or trastuzumab therapy. Echocardiography was performed prior to therapy initiation (baseline) and at standardized follow-up intervals during and after completion of therapy. Ejection fraction (EF), strain, strain rate, and ventricular-arterial coupling (effective arterial elastance [Ea]/end-systolic elastance [Eessb]) were quantitated. CTRCD was defined as a ≥10% reduction in EF from baseline to <50%. Multivariable logistic regression models were used to determine the associations between baseline levels and changes from baseline in echocardiographic measures and CTRCD. Receiver-operating characteristic curves were used to evaluate the predictive ability of these measures. In total, 135 participants contributed 517 echocardiograms to the analysis. Over a median follow-up time of 1.9 years (interquartile range: 0.9 to 2.4 years), 21 participants (15%) developed CTRCD. In adjusted models, baseline levels and changes in Ea/Eessb, circumferential strain, and circumferential strain rate were associated with 21% to 38% increased odds of CTRCD (p < 0.001). Changes in longitudinal strain (p = 0.037), radial strain (p = 0.015), and radial strain rate (p = 0.006) were also associated with CTRCD. Ea/Eessb (area under the curve: 0.703; 95% confidence interval: 0.583 to 0.807) and circumferential strain (area under the curve: 0.655; 95% confidence interval: 0.517 to 0.767) demonstrated the greatest predictive utility. Sensitivity analyses using an alternative CTRCD definition did not

  14. Influence of operating conditions and atomizer design on circumferential liquid distribution from small pressure-swirl atomizer

    NASA Astrophysics Data System (ADS)

    Malý, Milan; Janáčková, Lada; Jedelský, Jan; Jícha, Miroslav

    The spray symmetry is an important aspect in most practical applications. However, it is often an overlooked parameter. A measurement of circumferential distribution was carried out by a circular-sectored vessel on several pressure-swirl atomizers with spill-line over a wide range of injection pressure. The obtained results show that the spray uniformity improves markedly with the injection pressure. The increase in a number of tangential entry ports has only a minor effect on the spray uniformity. Even a small mechanical corruption of the atomizer internal parts negatively affects the spray patternation.

  15. Is circumferential minimally invasive surgery effective in the treatment of moderate adult idiopathic scoliosis?

    PubMed

    Anand, Neel; Baron, Eli M; Khandehroo, Babak

    2014-06-01

    Outcomes for minimally invasive scoliosis correction surgery have been reported for mild adult scoliosis. Larger curves historically have been treated with open surgical procedures including facet resections or posterior column osteotomies, which have been associated with high-volume blood loss. Further, minimally invasive techniques have been largely reported in the setting of degenerative scoliosis. We describe the effects of circumferential minimally invasive surgery (cMIS) for moderate to severe scoliosis in terms of (1) operative time and blood loss, (2) overall health and disease-specific patient-reported outcomes, (3) deformity correction and fusion rate, and (4) frequency and types of complications. Between January 2007 and January 2012, we performed 50 cMIS adult idiopathic scoliosis corrections in patients with a Cobb angle of greater than 30° but less than 75° who did not have prior thoracolumbar fusion surgery; this series represented all patients we treated surgically during that time meeting those indications. Our general indications for this approach during that period were increasing back pain unresponsive to nonoperative therapy with cosmetic and radiographic worsening of curves. Surgical times and estimated blood loss were recorded. Functional clinical outcomes including VAS pain score, Oswestry Disability Index (ODI), and SF-36 were recorded preoperatively and postoperatively. Patients' deformity correction was assessed on pre- and postoperative 36-inch (91-cm) standing films and fusion was assessed on CT scan. Minimum followup was 24 months (mean, 48 months; range, 24-77 months). Mean blood loss was 613 mL for one-stage surgery and 763 mL for two-stage surgery. Mean operative time was 351 minutes for one-stage surgery and 482 minutes for two-stage surgery. At last followup, mean VAS and ODI scores decreased from 5.7 and 44 preoperatively to 2.9 and 22 (p < 0.001 and 0.03, respectively) and mean SF-36 score increased from 48 preoperatively to

  16. Estimating the Extent of School Restructuring.

    ERIC Educational Resources Information Center

    Brief to Policymakers, 1992

    1992-01-01

    Findings of three studies that investigated the extent of school restructuring in American schools are presented in this paper. The data are combined from three different sources: (1) a national survey of 268 schools nominated for their successful restructuring programs; (2) a survey of 100 restructuring proposals submitted to a funding…

  17. 27 CFR 20.2 - Territorial extent.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Territorial extent. 20.2 Section 20.2 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS DISTRIBUTION AND USE OF DENATURED ALCOHOL AND RUM Scope § 20.2...

  18. 30 CFR 721.11 - Extent.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Extent. 721.11 Section 721.11 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR INITIAL PROGRAM... expected to cause significant, imminent environmental harm to land, air, or water resources; and (c) On a...

  19. The Aerodynamic Performance of an Over-The-Rotor Liner with Circumferential Grooves on a High Bypass Ratio Turbofan Rotor

    NASA Technical Reports Server (NTRS)

    Bozak, Rick; Hughes, Christopher; Buckley, James

    2013-01-01

    While liners have been utilized throughout turbofan ducts to attenuate fan noise, additional attenuation is obtainable by placing an acoustic liner over-the-rotor. Previous experiments have shown significant fan performance losses when acoustic liners are installed over-the-rotor. The fan blades induce an oscillating flow in the acoustic liners which results in a performance loss near the blade tip. An over-the-rotor liner was designed with circumferential grooves between the fan blade tips and the acoustic liner to reduce the oscillating flow in the acoustic liner. An experiment was conducted in the W-8 Single-Stage Axial Compressor Facility at NASA Glenn Research Center on a 1.5 pressure ratio fan to evaluate the impact of this over-the-rotor treatment design on fan aerodynamic performance. The addition of a circumferentially grooved over-the-rotor design between the fan blades and the acoustic liner reduced the performance loss, in terms of fan adiabatic efficiency, to less than 1% which is within the repeatability of this experiment.

  20. Circumferential fit assessment of CAD/CAM single crowns--a pilot investigation on a new virtual analytical protocol.

    PubMed

    Matta, Ragai E; Schmitt, Johannes; Wichmann, Manfred; Holst, Stefan

    2012-10-01

    Techniques currently applied to determine the marginal accuracy of dental crown restorations yield inadequate information. This investigation aimed to test a new virtual approach for determining the precision of fit of single-crown copings. Zirconia single crown copings were manufactured on 10 gypsum, single-tooth master casts with two different established computer-aided design/computer-assisted manufacture (CAD/CAM) systems (groups A and B). After cementation, the circumferential fit was assessed with an industrial noncontact scanner and virtual 3D analysis, following a triple-scan protocol. Marginal fit was determined by virtual sectioning; each abutment-coping complex was digitally sliced in 360 vertical sections (1 degree per section). Standardized measurement distances for analyzing the marginal fit (z, xy, xyz) were selected, and a crosshair alignment was utilized to determine whether crowns were horizontally and/or vertically too large or small. The Mann-Whitney test was applied to test for differences between groups. Significant differences in the xy direction (P = .008) were measured between groups. Group A showed a greater number of horizontally overextended margins and a higher frequency of xy distances greater than 150 Μm, in addition to a tendency for excessive z distances (P = .095). The mean marginal gap values were clinically acceptable in the present investigation; however, a full circumferential analysis revealed significant differences in marginal coping quality.

  1. Refinement and evaluation of crack-opening-area analyses for circumferential through-wall cracks in pipes

    SciTech Connect

    Rahman, S.; Brust, F.; Ghadiali, N.; Krishnaswamy, P.; Wilkowski, G.; Choi, Y.H. |; Moberg, F.; Brickstad, B. |

    1995-04-01

    Leak-before-break (LBB) analyses for circumferentially cracked pipes are currently being conducted in the nuclear industry to justify elimination of pipe whip restraints and jet impingement shields which are present because of the expected dynamic effects from pipe rupture. The application of the LBB methodology frequently requires calculation of leak rates. These leak rates depend on the crack-opening area of a through-wall crack in the pipe. In addition to LBB analyses, which assume a hypothetical flaw size, there is also interest in the integrity of actual leaking cracks corresponding to current leakage detection requirements in NRC Regulatory Guide 1.45, or for assessing temporary repair of Class 2 and 3 pipes that have leaks as are being evaluated in ASME Section 11. This study was requested by the NRC to review, evaluate, and refine current analytical models for crack-opening-area analyses of pipes with circumferential through-wall cracks. Twenty-five pipe experiments were analyzed to determine the accuracy of the predictive models. Several practical aspects of crack-opening such as; crack-face pressure, off-center cracks, restraint of pressure-induced bending, cracks in thickness transition regions, weld residual stresses, crack-morphology models, and thermal-hydraulic analysis, were also investigated. 140 refs., 105 figs., 41 tabs.

  2. Variations in pelvic dimensions do not predict the risk of circumferential resection margin (CRM) involvement in rectal cancer.

    PubMed

    Salerno, G; Daniels, I R; Brown, G; Norman, A R; Moran, B J; Heald, R J

    2007-06-01

    The objective of this study was to assess the value of preoperative pelvimetry, using magnetic resonance imaging (MRI), in predicting the risk of an involved circumferential resection margin (CRM) in a group of patients with operable rectal cancer. A cohort of 186 patients from the MERCURY study was selected. These patients' histological CRM status was compared against 14 pelvimetry parameters measured from the preoperative MRI. These measurements were taken by one of the investigators (G.S.), who was blinded to the final CRM status. There was no correlation between the pelvimetry and the CRM status. However, there was a difference in the height of the rectal cancer and the positive CRM rate (p = 0.011). Of 61 patients with low rectal cancer, 10 had positive CRM at histology (16.4% with CI 8.2%-22.1%) compared with 5 of 110 patients with mid/upper rectal cancers (4.5% with CI 0.7%-8.4%). Magnetic resonance imaging can predict clear margins in most cases of rectal cancer. Circumferential resection margin positivity cannot be predicted from pelvimetry in patients with rectal cancer selected for curative surgery. The only predictive factor for a positive CRM in the patients studied was tumor height.

  3. Statistical and Graphical Assessment of Circumferential and Radial Hardness Variation of AISI 4140, AISI 1020 and AA 6082 Aluminum Alloy

    PubMed Central

    Al-Khalid, Hamad; Alaskari, Ayman; Oraby, Samy

    2011-01-01

    Hardness homogeneity of the commonly used structural ferrous and nonferrous engineering materials is of vital importance in the design stage, therefore, reliable information regarding material properties homogeneity should be validated and any deviation should be addressed. In the current study the hardness variation, over wide spectrum radial locations of some ferrous and nonferrous structural engineering materials, was investigated. Measurements were performed over both faces (cross-section) of each stock bar according to a pre-specified stratified design, ensuring the coverage of the entire area both in radial and circumferential directions. Additionally the credibility of the apparatus and measuring procedures were examined through a statistically based calibration process of the hardness reference block. Statistical and response surface graphical analysis are used to examine the nature, adequacy and significance of the measured hardness values. Calibration of the apparatus reference block proved the reliability of the measuring system, where no strong evidence was found against the stochastic nature of hardness measures over the various stratified locations. Also, outlier elimination procedures were proved to be beneficial only at fewer measured points. Hardness measurements showed a dispersion domain that is within the acceptable confidence interval. For AISI 4140 and AISI 1020 steels, hardness is found to have a slight decrease trend as the diameter is reduced, while an opposite behavior is observed for AA 6082 aluminum alloy. However, no definite significant behavior was noticed regarding the effect of the sector sequence (circumferential direction). PMID:28817030

  4. Application of the line-spring model to a cylindrical shell containing a circumferential or axial part-through crack

    NASA Technical Reports Server (NTRS)

    Delale, F.; Erdogan, F.

    1981-01-01

    An approximate solution was obtained for a cylindrical shell containing a part-through surface crack. It was assumed that the shell contains a circumferential or axial semi-elliptic internal or external surface crack and was subjected to a uniform membrane loading or a uniform bending moment away from the crack region. A Reissner type theory was used to account for the effects of the transverse shear deformations. The stress intensity factor at the deepest penetration point of the crack was tabulated for bending and membrane loading by varying three dimensionless length parameters of the problem formed from the shell radius, the shell thickness, the crack length, and the crack depth. The upper bounds of the stress intensity factors are provided by the results of the elasticity solution obtained from the axisymmetric crack problem for the circumferential crack, and that found from the plane strain problem for a circular ring having a radial crack for the axial crack. The line-spring model gives the expected results in comparison with the elasticity solutions. Results also compare well with the existing finite element solution of the pressurized cylinder containing an internal semi-elliptic surface crack.

  5. Effects of extensive circumferential periosteal stripping on the microstructure and mechanical properties of the murine femoral cortex.

    PubMed

    Mercurio, Andrew D; Motta, Tatiana; Green, Eric; Noble, Garrett; Hart, Richard T; Allen, Matthew J

    2012-04-01

    Extensive periosteal stripping (PS) is a risk factor for post-radiation pathologic fracture following surgery for extremity soft tissue tumors. The purpose of this study was to determine the effects of PS on bone structure and mechanical properties. Thirty-one skeletally mature mice underwent PS, with circumferential removal of periosteum from an 8-mm segment of the mid-diaphysis of the left femur. Thirty-one control mice underwent sham surgery in which the femur was isolated without manipulation of the periosteum. At 2, 6, 12, or 26 weeks following surgery, the left femora were examined by micro-CT to quantify cortical thickness (CtTh), cross-sectional area (CSA), bone volume (BV), and polar moment of inertia (PMI). Three-point mechanical bend testing was performed and peak load, stiffness, and energy to failure were determined. PS resulted in significantly decreased CtTh, CSA, BV, and PMI at all time points. Peak load, stiffness, and energy to failure were significantly reduced at 2, 6, and 12 weeks. There were no significant differences in mechanical properties at 26 weeks. In this mouse model, extensive circumferential PS resulted in sustained changes in bone structure that were still evident after 6 months, accompanied by reductions in bone strength that persisted for at least 3 months.

  6. Circumferential watertight dural repair using nitinol U-clips in expanded endonasal and sublabial approaches to the cranial base.

    PubMed

    Acerbi, Francesco; Genden, Eric; Bederson, Joshua

    2010-12-01

    In recent years, significant advances have been made in the field of expanded endonasal approaches that permit treatment of different cranial base intradural lesions. To report our technique of cranial base dural repair by the application of nitinol U-Clips in endoscope-assisted extended endonasal or sublabial approaches. Closure techniques and postoperative cerebrospinal (CSF) leaks are reported. We reviewed 11 patients with different kinds of cranial base tumors or vascular diseases (2 tuberculum sellae meningiomas, 1 planum sphenoidale meningioma, 4 craniopharyngiomas, 1 recurrent clival chordoma, 1 esthesioneuroblastoma, 1 ethmoidal melanoma metastasis, 1 basilar trunk aneurysm) who underwent an endoscope-assisted extended endonasal or sublabial approach. Dural repair was performed using nitinol U-Clips to circumferentially suture AlloDerm or fascia lata directly to the existing dural borders. Lumbar drainage was not used in 9 patients and was used in 2 patients for 5 days. Patients were evaluated for the appearance of CSF leaks. Postoperative CSF leak was observed in 1 patient (9%). This required a second transnasal repair. Circumferential dural closure with U-Clips is a useful adjunct to prevent CSF leaks after expanded endonasal or sublabial approaches to the cranial base for treatment of intracranial pathology.

  7. Measurement of the longitudinal and circumferential muscular activity associated with peristalsis using a single fibre grating array

    NASA Astrophysics Data System (ADS)

    Arkwright, J. W.; Blenman, N. G.; Underhill, I. D.; Maunder, S. A.; Spencer, N. J.; Costa, M.; Brooks, S. J.; Szczesniak, M. M.; Dinning, P. G.

    2010-09-01

    Diagnostic catheters based on fibre Bragg gratings (FBG's) are proving to be highly effective for measurement of the muscular activity associated with peristalsis in the human gut. The primary muscular contractions that generate peristalsis are circumferential in nature; however, it has long been known that there is also a component of longitudinal contractility present, acting in harmony with the circumferential component to improve the overall efficiency of material movement. To date, there have been relatively few reports on the measurement or inference of longitudinal contractions in humans and all have been limited to detection at a single location only. This is due to the lack of a viable recording technique suitable for real-time in-vivo measurement of this type of activity over extended lengths of the gut. We report the detection of longitudinal motion in lengths of excised mammalian colon using an FBG technique that should be viable for similar detection in humans. The longitudinal sensors have been combined with our previously reported FBG pressure sensing elements to form a composite catheter that allows the relative phase between the two components to be detected. The catheter output has been validated using digital video mapping in an ex-vivo animal preparation using lengths of rabbit ileum.

  8. The Aerodynamic Performance of an Over-the-Rotor Liner With Circumferential Grooves on a High Bypass Ratio Turbofan Rotor

    NASA Technical Reports Server (NTRS)

    Bozak, Richard F.; Hughes, Christopher E.; Buckley, James

    2013-01-01

    While liners have been utilized throughout turbofan ducts to attenuate fan noise, additional attenuation is obtainable by placing an acoustic liner over-the-rotor. Previous experiments have shown significant fan performance losses when acoustic liners are installed over-the-rotor. The fan blades induce an oscillating flow in the acoustic liners which results in a performance loss near the blade tip. An over-the-rotor liner was designed with circumferential grooves between the fan blade tips and the acoustic liner to reduce the oscillating flow in the acoustic liner. An experiment was conducted in the W-8 Single-Stage Axial Compressor Facility at NASA Glenn Research Center on a 1.5 pressure ratio fan to evaluate the impact of this over-the-rotor treatment design on fan aerodynamic performance. The addition of a circumferentially grooved over-the-rotor design between the fan blades and the acoustic liner reduced the performance loss, in terms of fan adiabatic efficiency, to less than 1 percent which is within the repeatability of this experiment.

  9. The Aerodynamic Performance of an Over-The-Rotor Liner with Circumferential Grooves on a High Bypass Ratio Turbofan Rotor

    NASA Technical Reports Server (NTRS)

    Bozak, Rick; Hughes, Christopher; Buckley, James

    2013-01-01

    While liners have been utilized throughout turbofan ducts to attenuate fan noise, additional attenuation is obtainable by placing an acoustic liner over-the-rotor. Previous experiments have shown significant fan performance losses when acoustic liners are installed over-the-rotor. The fan blades induce an oscillating flow in the acoustic liners which results in a performance loss near the blade tip. An over-the-rotor liner was designed with circumferential grooves between the fan blade tips and the acoustic liner to reduce the oscillating flow in the acoustic liner. An experiment was conducted in the W-8 Single-Stage Axial Compressor Facility at NASA Glenn Research Center on a 1.5 pressure ratio fan to evaluate the impact of this over-the-rotor treatment design on fan aerodynamic performance. The addition of a circumferentially grooved over-the-rotor design between the fan blades and the acoustic liner reduced the performance loss, in terms of fan adiabatic efficiency, to less than 1% which is within the repeatability of this experiment.

  10. Recurrence of atrial fibrillation correlates with the extent of post-procedural late gadolinium enhancement: a pilot study.

    PubMed

    Peters, Dana C; Wylie, John V; Hauser, Thomas H; Nezafat, Reza; Han, Yuchi; Woo, Jeong Joo; Taclas, Jason; Kissinger, Kraig V; Goddu, Beth; Josephson, Mark E; Manning, Warren J

    2009-03-01

    We sought to evaluate radiofrequency (RF) ablation lesions in atrial fibrillation (AF) patients using cardiac magnetic resonance (CMR), and to correlate the ablation patterns with treatment success. RF ablation procedures for treatment of AF result in localized scar that is detected by late gadolinium enhancement (LGE) CMR. We hypothesized that the extent of scar in the left atrium and pulmonary veins (PV) would correlate with moderate-term procedural success. Thirty-five patients with AF, undergoing their first RF ablation procedure, were studied. The RF ablation procedure was performed to achieve bidirectional conduction block around each PV ostium. AF recurrence was documented using a 7-day event monitor at multiple intervals during the first year. High spatial resolution 3-dimensional LGE CMR was performed 46 +/- 28 days after RF ablation. The extent of scarring around the ostia of each PV was quantitatively (volume of scar) and qualitatively (1: minimal, 3: extensive and circumferential) assessed. Thirteen (37%) patients had recurrent AF during the 6.7 +/- 3.6-month observation period. Paroxysmal AF was a strong predictor of nonrecurrent AF (15% with recurrence vs. 68% without, p = 0.002). Qualitatively, patients without recurrence had more completely circumferentially scarred veins (55% vs. 35% of veins, p = NS). Patients without recurrence more frequently had scar in the inferior portion of the right inferior pulmonary vein (RIPV) (82% vs. 31%, p = 0.025, Bonferroni corrected). The volume of scar in the RIPV was quantitatively greater in patients without AF recurrence (p < or = 0.05) and was a univariate predictor of recurrence using Cox regression (p = 0.049, Bonferroni corrected). Among patients undergoing PV isolation, AF recurrence during the first year is associated with a lesser degree of PV and left atrial scarring on 3-dimensional LGE CMR. This finding was significant for RIPV scar and may have implications for the procedural technique used in PV

  11. The extent of burning in African savanna

    NASA Technical Reports Server (NTRS)

    Cahoon, D. R. JR.; Levine, J. S.; Cofer, W. R. Iii; Stocks, B. J.

    1994-01-01

    The temporal and spatial distribution of African savanna grassland fires has been examined, and the areal extent of these fires has been estimated for the subequatorial African continent. African savanna fires have been investigated using remote sensing techniques and imagery collected by low-light sensors on Defense Meteorological Satellite Program (DMSP) satellites and by the Advanced Very High Resolution Radiometer (AVHRR) which is aboard polar orbiting National Oceanic and Atmospheric Administration (NOAA) satellites. DMSP imagery has been used to map the evolution of savanna burning over all of the African continent and the analysis of AVHRR imagery has been used to estimate the areal extent of the burning in the southern hemispheric African savannas. The work presented primarily reflects the analysiscompleted for the year 1987. However, comparisons have been made with other years and the representativeness of the 1987 analysis is discussed.

  12. The extent of forest in dryland biomes

    Treesearch

    Jean-Francois Bastin; Nora Berrahmouni; Alan Grainger; Danae Maniatis; Danilo Mollicone; Rebecca Moore; Chiara Patriarca; Nicolas Picard; Ben Sparrow; Elena Maria Abraham; Kamel Aloui; Ayhan Atesoglu; Fabio Attore; Caglar Bassullu; Adia Bey; Monica Garzuglia; Luis G. GarcÌa-Montero; Nikee Groot; Greg Guerin; Lars Laestadius; Andrew J. Lowe; Bako Mamane; Giulio Marchi; Paul Patterson; Marcelo Rezende; Stefano Ricci; Ignacio Salcedo; Alfonso Sanchez-Paus Diaz; Fred Stolle; Venera Surappaeva; Rene Castro

    2017-01-01

    Dryland biomes cover two-fifths of Earth’s land surface, but their forest area is poorly known. Here, we report an estimate of global forest extent in dryland biomes, based on analyzing more than 210,000 0.5-hectare sample plots through a photo-interpretation approach using large databases of satellite imagery at (i) very high spatial resolution and (ii) very high...

  13. Identifying the extent of a Superfund site

    SciTech Connect

    Gowland, P.A.; Chantry, W.; Wisniewski, R.

    1995-12-31

    There has been considerable misunderstanding regarding the extent of private and Federal facility sites listed under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) or Superfund program. This problem, which occurs primarily at the time of proposal or finalization of a site to the National Priorities List (NPL), seems to be due both to semantics and errors in perception. The term ``site`` has been used differently in performing CERCLA removal and remediation activities, in the installation restoration programs of various Federal agencies, and by the public when preparing comments on proposed NPL sites. It has been confused with the terms source, solid waste management unit, and facility. The most common interpretation by the public of the term ``site`` and its extent is that the site encompasses the property owned by the facility named in the NPL designation or at which a removal has occurred. However, based on the related definitions in CERCLA, a site is best defined as the location of a release (or releases) of hazardous substances and wherever the hazardous substances have come to be located. The extent of a site neither is limited by property boundaries, nor does it include clean areas within a facility`s boundaries. This paper will identify the basis for the Environmental Protection Agency`s (EPA`s) definition of site for Superfund purposes, including aggregated sites, relevant court decisions and statements of EPA policy, and provide case histories of how this definition has been applied at both private and Federal facilities.

  14. Compromises between Circumpolar Vortex and Cryospheric Extent

    NASA Astrophysics Data System (ADS)

    Choi, G.; Robinson, D. A.; Kim, J.

    2014-12-01

    Potential linkages between the circumpolar vortex (CV) and snow/ice cover in both hemispheres are examined for better seasonal and longer-term climate predictions. Long-term (1951~present) maps and statistics of daily/monthly CV size, perimeter and circularity ratio (CR) are produced from the NCEP/NCAR reanalysis 500hPa pressure data sets using Geographic Information System (GIS). Temporal lead/lag correlations of CV variables with circumpolar cryospheric variables including Rutgers University's Global Snow Lab. Northern Hemisphere snow extent (1967~present) and National Snow & Ice Data Center (NSIDC)'s Arctic/Antarctic Ice Extent (1979~present) data are investigated. Analyses of daily/monthly data show that intra-annual variability of and long-term changes in the CV spatial pattern are associated with those of circumpolar cryospheric covers in both hemispheres. Thermal contrast amplified along their boundaries due to cryospheric albedo feedback may account for these potential linkages. Consistency and dissimilarities at regional scales between circumpolar cryospheric extent and atmospheric circulation will also be discussed in detail. Key words: circumpolar vortex, cryospheric feedbacks, climate variability and change.

  15. Clinical implications of the P wave duration and dispersion: relationship between atrial conduction defects and abnormally prolonged and fractionated atrial endocardial electrograms.

    PubMed

    Centurión, Osmar Antonio

    2009-05-01

    Atrial conduction disease provides a suitable substrate for reentry and appears to be a major predisposing factor for the development of atrial fibrillation. It was demonstrated that when depressed conduction was observed in recordings from human atrial muscle, the ultra-structure was usually abnormal. Areas of poorly coupled fibers in diseased atrial tissue with progressive fibro-degenerative changes may lead to abnormal electrophysiological characteristics. Structural inhomogeneity or local differences in electrophysiological or ultra-structural properties are considered to play a major role in the initiation of reentrant circuits due to the increased likelihood of unidirectional block of the premature impulse. The P wave of the electrocardiogram may show alterations that can be associated with atrial arrhythmias. It was shown that there is a statistical association between the low resting membrane potential and a prolonged P wave duration. Also a prolonged inter-atrial conduction time was significantly related to abnormal P wave morphology. In the evaluation of patients with altered P waves in the electrocardiogram, it is very important to keep in mind that, patients who have a great susceptibility to develop AF possess abnormally prolonged and fractionated atrial endocardial electrograms in sinus rhythm within the right atrium, a significantly longer P wave duration, a significantly longer intra-atrial and inter-atrial conduction time of sinus impulses; and a significantly greater sinus node dysfunction and higher incidence of induction of sustained atrial fibrillation. Awareness of this strong association may lead to a better therapeutic management in individual patients.

  16. Mesenchymal stem cell delivery into rat infarcted myocardium using a porous polysaccharide-based scaffold: a quantitative comparison with endocardial injection

    PubMed Central

    Le Visage, Catherine; Gournay, Olivier; Benguirat, Najah; Hamidi, Sofiane; Chaussumier, Laetitia; Mougenot, Nathalie; Flanders, James A.; Isnard, Richard; Michel, Jean-Baptiste; Hatem, Stéphane N.; Letourneur, Didier; Norol, Francoise

    2012-01-01

    The use of mesenchymal stem cells (MSCs) for tissue regeneration is often hampered by modest engraftment in host tissue. This study was designed to quantitatively compare MSCs engraftment rates after delivery using a polysaccharide-based porous scaffold or endocardial (EC) injection in a rat myocardial infarction model. Cellular engraftment was measured by quantitative RT-PCR using MSCs previously transduced with a lentiviral vector that expresses GFP. The use of a scaffold promoted local cellular engraftment and survival. The number of residual GFP+ cells was greater with the scaffold than after EC injection (9.7% vs 5.1% at 1 month and 16.3% vs 6.1% at 2 months, respectively (n=5)). This concurred with a slight increase in mRNA VEGF level in the scaffold group (p<0.05). Clusters of GFP+ cells were detected in the peri-infarct area, mainly phenotypically consistent with immature MSCs. Functional assessment by echocardiography at 2 months post infarct also showed a trend towards a lower left ventricular dilatation and a reduced fibrosis in the scaffold group in comparison to direct injection group (n=10). These findings demonstrate that using a porous biodegradable scaffold is a promising method to improve cell delivery and engraftment into damaged myocardium. PMID:21770864

  17. Biodegradable esophageal stent placement does not prevent high-grade stricture formation after circumferential mucosal resection in a porcine model

    PubMed Central

    Schomisch, Steve J.; Furlan, Joseph P.; Marks, Andrea S.; Chak, Amitabh; Lash, Richard H.; Ponsky, Jeffrey L.; Marks, Jeffrey M.

    2015-01-01

    Background Advanced esophageal dysplasia and early cancers have been treated traditionally with esophagectomy. Endoscopic esophageal mucosectomy (EEM) offers less-invasive therapy, but high-degree stricture formation limits its applicability. We hypothesized that placement of a biodegradable stent (BD-stent) immediately after circumferential EEM would prevent stricturing. Methods Ten pigs (five unstented controls, five BD-stent) were utilized. Under anesthesia, a flexible endoscope with a band ligator and snare was used to incise the mucosa approximately 20 cm proximal to the lower esophageal sphincter. A 10-cm, circumferential, mucosal segment was dissected and excised by using snare electrocautery. In the stented group, an 18-×120-mm, self-expanding, woven polydioxanone stent (ELLA-CS, Hradec-Kralove) was deployed. Weekly esophagograms evaluated for percent reduction in esophageal diameter, stricture length, and proximal esophageal dilation. Animals were euthanized when the stricture exceeded 80 % and were unable to gain weight (despite high-calorie liquid diet) or at 14 weeks. Results The control group rapidly developed esophageal strictures; no animal survived beyond the third week of evaluation. At 2 weeks post-EEM, the BD-stent group had a significant reduction in esophageal diameter (77.7 vs. 26.6 %, p < 0.001) and degree of proximal dilation (175 vs. 131 %, p = 0.04) compared with controls. Survival in the BD-stent group was significantly longer than in the control group (9.2 vs. 2.4 weeks, p = 0.01). However, all BD-stent animals ultimately developed clinically significant strictures (range, 4–14 weeks). Comparison between the maximum reduction in esophageal diameter and stricture length (immediately before euthanasia) demonstrated no differences between the groups. Conclusions Circumferential EEM results in severe stricture formation and clinical deterioration within 3 weeks. BD-stent placement significantly delays the time of clinical deterioration

  18. Effects of radial and circumferential inlet velocity profile distortions on performance of a short-length double-annular ram induction combustor

    NASA Technical Reports Server (NTRS)

    Schultz, D. F.; Perkins, P. J.

    1972-01-01

    Inlet air velocity profile tests were conducted on a full-scale short-length 102-centimeter-diameter annual combustor designed for advanced gas turbine engine applications. The inlet profiles studied include radial distortions that were center peaked, and tip peaked, as well as a circumferential distortion which was center peaked for one-third of the circumference and flat for the other two-thirds. An increase in combustor pressure loss was the most significant effect of the radial air velocity distortions. With the circumferential distortion, exit temperature pattern factor doubled when compared to a flat velocity profile.

  19. Dorsal median lipectomy (the arrow technique): A new approach for the treatment of the circumferential truncal skin and fatty tissue excess.

    PubMed

    Almousawi, H S; Assaf, N; Herlin, C; Alharbi, M; Michel, G; Sinna, R; Dast, S

    2017-08-01

    The increase in the number of patients who undergo massive weight loss surgery has led to an increasing number of patients who complain of circumferential abdominal skin and soft tissue excess. Currently, the only surgical option to treat soft tissue excess is vertical median abdominal lipectomy (fleur-de-lys technique). However, many patients are reluctant to undergo this surgery because of the position of the scar. We presented a new surgical approach to manage circumferential excess - dorsal median lipectomy (arrow technique) - in which the dorsal scar is well-tolerated by patients. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  20. Ground Tests of a Radial Air-Cooled Engine to Correct a Poor Circumferential Pressure-Recovery Distribution

    NASA Technical Reports Server (NTRS)

    Gallagher, James J.

    1948-01-01

    This report presents the results of the tests of a power-plant installation to improve the circumferential pressure-recovery distribution at the face of the engine. An underslung "C" cowling was tested with two propellers with full cuffs and with a modification to one set of cuffs. Little improvement was obtained because the base sections of the cuffs were stalled. A set of guide vanes boosted the over-all pressures and helped the pressure recoveries for a few of the cylinders. Making the underslung cowling into a symmetrical "C" cowling evened the pressure distribution; however, no increases in front pressures were obtained. The pressures at the top cylinders remained low and the high pressures at the bottom cylinders were reduced. At higher powers and engine speeds, the symmetrical cowling appeared best from the standpoint of over-all cooling characteristics.

  1. The stability of a circumferential crack in a pipe I. The influence of the boundary conditions imposed at the ends

    NASA Astrophysics Data System (ADS)

    Smith, E.

    THE PAPER examines the case where a pipe of length L is built-in at one end and the other end is subject to an imposed displacement or rotation. The criterion for instability of growth of a circumferential through-wall crack is shown to depend on the pipe-end boundary conditions as well as the pipe geometry, crack size and crack location. The worst possible case is that where there is only a force, but no moment, at the pipe-end. However, this is probably an artificial situation which is unlikely to arise in practice. A pipe is more likely to be built-in at both ends, and for this situation, it is concluded that the instability criterion is the same irrespective of whether a displacement or rotation is imposed at a built-in end.

  2. Transverse shear effects on the stress-intensity factor for a circumferentially cracked, specially orthotropic cylindrical shell

    NASA Technical Reports Server (NTRS)

    Delale, F.; Erdogan, F.

    1977-01-01

    The problem of a cylindrical shell containing a circumferential through crack is considered by taking into account the effect of transverse shear deformations. The formulation is given for a specially orthotropic material within the confines of a linearized shallow shell theory. The particular theory used permits the consideration of all five boundary conditions regarding moment and stress resultants on the crack surface. Consequently, aside from multiplicative constants representing the stress intensity factors, the membrane and bending components of the asymptotic stress fields near the crack tip are found to be identical. The stress intensity factors are calculated separately for a cylinder under a uniform membrane load, and that under a uniform bending moment. Sample results showing the nature of the out-of-plane crack surface displacement and the effect of the Poisson's ratio are presented.

  3. Numerical Simulation and Experimental Investigation of Residual Stresses in the Circumferential Butt GTAW of Incoloy 800H Pipes

    NASA Astrophysics Data System (ADS)

    Purmohamad, H.; Kermanpur, A.; Shamanian, M.

    2010-02-01

    The residual stresses developed during the circumferential butt gas tungsten arc welding (GTAW) process of Incoloy 800H pipes were simulated using the finite element method. A decoupled thermostructural model was developed in three dimensions. The element birth and death technique was used for the addition of filler material in the weld pool. The Goldak double ellipsoidal model was used to simulate the distribution of arc heat during welding. The plastic behavior of the material was described by Von Mises yield function and the bilinear kinematics hardening was assumed. To validate the thermostructural model, both temperature and residual stress distributions within the pipes were measured using thermocouples and strain gages, respectively. Good agreements were found between the experimental and simulation results. The model was then used to predict distribution of residual stresses during the GTAW of Incoloy 800H pipes and to study effects of process parameters on the residual stresses.

  4. Comparative charge analysis of one- and two-level lumbar total disc arthroplasty versus circumferential lumbar fusion.

    PubMed

    Levin, David A; Bendo, John A; Quirno, Martin; Errico, Thomas; Goldstein, Jeffrey; Spivak, Jeffrey

    2007-12-01

    This is a retrospective, independent study comparing 2 groups of patients treated surgically for discogenic low back pain associated with degenerative disc disease (DDD) in the lumbosacral spine. To compare the surgical and hospitalization charges associated with 1- and 2-level lumbar total disc replacement and circumferential lumbar fusion. Reported series of lumbar total disc replacement have been favorable. However, economic aspects of lumbar total disc replacement (TDR) have not been published or studied. This information is important considering the recent widespread utilization of new technologies. Recent studies have demonstrated comparable short-term clinical results between TDR and lumbar fusion recipients. Relative charges may be another important indicator of the most appropriate procedure. We report a hospital charge-analysis comparing ProDisc lumbar disc replacement with circumferential fusion for discogenic low back pain. In a cohort of 53 prospectively selected patients with severe, disabling back pain and lumbar disc degeneration, 36 received Synthes ProDisc TDR and 17 underwent circumferential fusion for 1- and 2-level degenerative disc disease between L3 and S1. Randomization was performed using a 2-to-1 ratio of ProDisc recipients to control spinal fusion recipients. Charge comparisons, including operating room charges, inpatient hospital charges, and implant charges, were made from hospital records using inflation-corrected 2006 U.S. dollars. Operating room times, estimated blood loss, and length of stay were obtained from hospital records as well. Surgeon and anesthesiologist fees were, for the purposes of comparison, based on Medicare reimbursement rates. Statistical analysis was performed using a 2-tailed Student t test. For patients with 1-level disease, significant differences were noted between the TDR and fusion control group. The mean total charge for the TDR group was $35,592 versus $46,280 for the fusion group (P = 0.0018). Operating

  5. High-Density Electron-Beam Recording of Circumferentially Aligned Dots by Using Substrates with Low Atomic Numbers

    NASA Astrophysics Data System (ADS)

    Okada, Takeru; Aida, Makoto; Fujimori, Jiro; Katsumura, Masahiro; Iida, Tetsuya

    2012-01-01

    Reducing proximity effects is a key factor for achieving a higher resolution in electron-beam lithography and realizing the mastering of patterned media. The effect of substrate materials on backscattering electrons was investigated by simulation and experiment, and resolution enhancement was demonstrated. In Monte Carlo simulations with 100 keV incident electrons, the intensity of backscattering electrons decreased with decreasing atomic number of substrates. On the other hand, both the density of substrates and the existence of 10 nm thin films had negligible effects on the intensity of backscattering electrons. The measured exposure distributions from line-scanned electron beams supported the results of simulations. The intensity of backscattering electrons was reduced by using a carbon substrate, and circumferentially aligned high-density patterns of 878 Gbit/in.2 were resolved.

  6. Sarcoidosis Extent Relates to Molecular Variability.

    PubMed

    Monast, Calixte S; Li, Katherine; Judson, Marc A; Baughman, Robert P; Wadman, Eric; Watt, Rosemary; Silkoff, Philip E; Barnathan, Elliot S; Brodmerkel, Carrie

    2017-02-16

    The molecular basis of sarcoidosis phenotype heterogeneity and its relationship to effective treatment of sarcoidosis have not been elucidated. Peripheral samples from sarcoidosis subjects who participated in a phase 2 study of golimumab (anti-TNFα) and ustekinumab (anti-IL12p40) were used to measure the whole blood transcriptome and levels of serum proteins. Differential gene and protein expression analyses were used to explore the molecular differences between sarcoidosis phenotypes as defined by extent of organ involvement. The same data were also used in conjunction with an enrichment algorithm to identify gene expression changes associated with treatment with study drugs compared to placebo. Our analyses revealed marked heterogeneity among the three sarcoidosis phenotypes included in the study cohort, including striking differences in enrichment of the Interferon Pathway. Conversely, enrichments of multiple pathways, including T Cell Receptor Signaling, were similar among phenotypes. We also identify differences between treatment with golimumab and ustekinumab that may explain the differences in trends for clinical efficacy observed in the trial. We find that molecular heterogeneity is associated with sarcoidosis in a manner that may be related to the extent of organ involvement. These findings may help explain the difficulty in identifying clinically efficacious sarcoidosis treatments and suggest hypotheses for improved therapeutic strategies. This article is protected by copyright. All rights reserved.

  7. Circumferential targeted renal sympathetic nerve denervation with preservation of the renal arterial wall using intra-luminal ultrasound

    NASA Astrophysics Data System (ADS)

    Roth, Austin; Coleman, Leslie; Sakakura, Kenichi; Ladich, Elena; Virmani, Renu

    2015-03-01

    An intra-luminal ultrasound catheter system (ReCor Medical's Paradise System) has been developed to provide circumferential denervation of the renal sympathetic nerves, while preserving the renal arterial intimal and medial layers, in order to treat hypertension. The Paradise System features a cylindrical non-focused ultrasound transducer centered within a balloon that circulates cooling fluid and that outputs a uniform circumferential energy pattern designed to ablate tissues located 1-6 mm from the arterial wall and protect tissues within 1 mm. RF power and cooling flow rate are controlled by the Paradise Generator which can energize transducers in the 8.5-9.5 MHz frequency range. Computer simulations and tissue-mimicking phantom models were used to develop the proper power, cooling flow rate and sonication duration settings to provide consistent tissue ablation for renal arteries ranging from 5-8 mm in diameter. The modulation of these three parameters allows for control over the near-field (border of lesion closest to arterial wall) and far-field (border of lesion farthest from arterial wall, consisting of the adventitial and peri-adventitial spaces) depths of the tissue lesion formed by the absorption of ultrasonic energy and conduction of heat. Porcine studies have confirmed the safety (protected intimal and medial layers) and effectiveness (ablation of 1-6 mm region) of the system and provided near-field and far-field depth data to correlate with bench and computer simulation models. The safety and effectiveness of the Paradise System, developed through computer model, bench and in vivo studies, has been demonstrated in human clinical studies.

  8. CFD Study of the Hydrocarbon Boost Low-Pressure Inducer and Kicker in the Presence of a Circumferential Groove

    NASA Technical Reports Server (NTRS)

    Coker, Robert

    2011-01-01

    Results are presented of a computational fluid dynamics (CFD) study done in support of Marshall Space Flight Center's (MSFC) sub-scale water flow experiments of the Hydrocarbon Boost (HCB) Oxidizer Turbopump (OTP) being developed by the Air Force Research Laboratory (AFRL) and Aerojet. A circumferential groove may be added to the pump to reduce synchronous cavitation and subsequent bearing loads at a minimal performance cost. However, the energy may reappear as high order cavitation (HOC) that spans a relatively large frequency range. Thus, HOC may have implications for the full-scale OTP inducer in terms of reduced structural margin at higher mode frequencies. Simulations using the LOCI/Stream CFD program were conducted in order to explore the fluid dynamical impact of the groove on the low-pressure inducer and kicker. It was found that the circumferential groove has minimal head performance impact, but causes back-flowing high-swirl fluid to interact with the nearly-axial incoming fluid just above the inducer blades. The high-shear interface between the fluids is Kelvin-Helmholtz unstable, resulting in trains of low pressure regions or 'pearls' forming near the upstream edge of the groove. When the static pressure in these regions becomes low enough and they get cut by the blade leading edge, HOC is thought to occur. Although further work is required, the numerical models indicate that HOC will occur in the runbox of the AFRL/Aerojet HCB OTP. Comparisons to the ongoing water flow experiments will be discussed, as well as possible designs that may mitigate HOC while continuing to reduce synchronous cavitation. December 2011 MSS/LPS/SPS Joint Subcommittee Meeting ABSTRACT SUBMITTAL FORM

  9. Circumferential esophageal replacement using a tube-shaped tissue-engineered substitute: An experimental study in minipigs.

    PubMed

    Poghosyan, Tigran; Sfeir, Rony; Michaud, Laurent; Bruneval, Patrick; Domet, Thomas; Vanneaux, Valerie; Luong-Nguyen, Minh; Gaujoux, Sebastien; Gottrand, Frederic; Larghero, Jerome; Cattan, Pierre

    2015-07-01

    Esophageal replacement by the colon or the stomach for malignant and nonmalignant esophageal diseases exposes to significant morbidity and mortality. In this setting, tissue engineering seems to be a seductive alternative. In a porcine model, we performed a 5-cm-long circumferential replacement of the cervical esophagus by a tubulized acellular matrix (small intestinal submucosa) cellularized with autologous skeletal myoblasts and covered by a human amniotic membrane seeded with autologous oral epithelial cells. The substitute was grown for 2 weeks in the great omentum before esophageal replacement. Eighteen minipigs (divided into 3 groups: group A [substitute with esophageal endoprothesis; n = 6], group B [substitute alone; n = 6], and group C [endoprothesis alone; n = 6]) were included. The esophageal endoprothesis was removed at 6 months. Animals were killed sequentially over a 12 month-period. Clinical, endoscopic, radiologic and histologic outcomes were analyzed. All animals except 1 of in groups B and C died during the first 2 months owing to refractory esophageal stenosis or endoprothesis extrusion. Nutritional autonomy without endoprothesis was observed in all animals of group A with a follow-up of >6 months (n = 3). A phenotype similar to that of native esophagus, consisting of a mature epithelium, submucosal glands, and a circular muscular layer, was observed after 9 months. In this model, the circumferential replacement of the cervical esophagus by a tube-shaped tissue-engineered substitute under the temporary cover of an esophageal endoprothesis allowed nutritional autonomy and tissue remodeling toward an esophageal phenotype. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Adjacent segment degeneration and revision surgery after circumferential lumbar fusion: outcomes throughout 15 years of follow-up.

    PubMed

    Maruenda, José I; Barrios, Carlos; Garibo, Felipe; Maruenda, Borja

    2016-05-01

    This retrospective study analyzes long-term outcomes (15 years) of circumferential lumbar fusion (CF) for degenerative spine disease using instrumented PLIF. The occurrence of adjacent segment degeneration (ASD) and the reintervention rate was specially focused. A series of 73 patients who underwent CF (1-3 levels) was reviewed. Patients were evaluated preoperatively, at 2, 5, 10 and 15 years after surgery with static and dynamic radiographic studies, CT scan and MRI. Patients completed also the Oswestry-Disability index (ODI), the VAS score, and the patient self-satisfaction questionnaire. At 2-year follow-up, there was a decrease in the average ODI score (from 72.3 ± 16.4 preop to 30.5 ± 6.2). At 10- and 15-year follow-up, ODI scores return to preoperative scores in patients without revision surgery. The 82.8 % of patients referred an excellentgood self-satisfaction rate at this time. At 5-year follow-up, seven patients (9.6 %) required reoperation because of symptomatic ASD. At 10-year follow-up, reoperated patients increased to 24.6 % (18 cases). Excellent and good self-satisfaction rate decreased to 41.1 % at this time. Radiological ASD was then detected in 37 cases (50.7 %). At 15-year follow-up, nine patients were lost and a total of 24 (37.5 %) required a new surgical treatment because of ASD. The occurrence of revision surgery because of symptomatic ASD was highly dependent of the age of patients at the first surgery and the number of fused levels. Circumferential lumbar fusion provides good clinical results at short-term follow-up. From 2- to 15-year follow-up, outcome worsened significantly. The high rate of ASD occurrence and reintervention questions the reliability of this technique for lumbar fusion.

  11. The Influence of Hospital Volume on Circumferential Resection Margin Involvement: Results of the Dutch Surgical Colorectal Audit.

    PubMed

    Gietelink, Lieke; Henneman, Daniel; van Leersum, Nicoline J; de Noo, Mirre; Manusama, Eric; Tanis, Pieter J; Tollenaar, Rob A E M; Wouters, Michel W J M

    2016-04-01

    This population-based study evaluates the association between hospital volume and CRM (circumferential resection margin) involvement, adjusted for other confounders, in rectal cancer surgery. A low hospital volume (<20 cases/year) was independently associated with a higher risk of CRM involvement (odds ratio=1.54; 95% CI: 1.12-2.11). To evaluate the association between hospital volume and CRM (circumferential resection margin) involvement in rectal cancer surgery. To guarantee the quality of surgical treatment of rectal cancer, the Association of Surgeons of the Netherlands has stated a minimal annual volume standard of 20 procedures per hospital. The influence of hospital volume has been examined for different outcome variables in rectal cancer surgery. Its influence on the pathological outcome (CRM) however remains unclear. As long-term outcomes are best predicted by the CRM status, this parameter is of essential importance in the debate on the justification of minimal volume standards in rectal cancer surgery. Data from the Dutch Surgical Colorectal Audit (2011-2012) were used. Hospital volume was divided into 3 groups, and baseline characteristics were described. The influence of hospital volume on CRM involvement was analyzed, in a multivariate model, between low- and high-volume hospitals, according to the minimal volume standards. This study included 5161 patients. CRM was recorded in 86% of patients. CRM involvement was 11% in low-volume group versus 7.7% and 7.9% in the medium- and high-volume group (P≤0.001). After adjustment for relevant confounders, the influence of hospital volume on CRM involvement was still significant odds ratio (OR) = 1.54; 95% CI: 1.12-2.11). The outcomes of this pooled analysis support minimal volume standards in rectal cancer surgery. Low hospital volume was independently associated with a higher risk of CRM involvement (OR = 1.54; 95% CI: 1.12-2.11).

  12. 46 CFR 172.135 - Extent of damage.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    .... Vertical extent From the baseline upward without limit. Grounding Penetration At the Forward End But.... Transverse extent B/6 or 32.81 feet (10m) whichever is shorter. Vertical extent from the baseline upward B/15... Longitudinal extent L/10 or 16.41 feet (5m) whichever is shorter. Transverse extent 16.41 feet (5m). Vertical...

  13. Noninvasive quantification of the extent of jeopardized myocardium in patients with single-vessel coronary disease by stress thallium-201 single-photon emission computerized rotational tomography

    SciTech Connect

    Prigent, F.; Maddahi, J.; Garcia, E.; Van Train, K.; Friedman, J.; Berman, D.

    1986-03-01

    In 22 patients with single-vessel coronary artery disease and no history of infarction, stress Tl-201 rotational tomography was used to quantify the extent of jeopardized myocardium. The vertical long- and short-axis tomograms were quantified by means of maximum-count circumferential profile analysis. The scintigraphic extent of jeopardized myocardium was expressed as the percentage of profile points falling 2.5 standard deviations below a previously established mean normal profile and was correlated to a quantitatively expressed angiographic extent of jeopardized myocardium. The extent of jeopardized myocardium varied from 1% to 55% by tomography and 8% to 50% by angiography and correlated with an r = 0.79 and a 10% standard error of the estimate. Defect intensity, reflecting the mean depth by which the abnormal points fell below the normal value of greater than or equal to 10%, was 100% specific for a coronary stenosis of greater than or equal to 70%. In conclusion, this study demonstrates that: patients with single-vessel disease have highly variable extents of hypoperfused myocardium defined by Tl-201 tomography and coronary arteriography, there is a fair relationship between angiographic jeopardy score and perfusion defects by Tl-201 tomography during exercise, and Tl-201 tomography may be used to noninvasively determine the extent of hypoperfused myocardium in coronary artery disease.

  14. The extent of forest in dryland biomes.

    PubMed

    Bastin, Jean-François; Berrahmouni, Nora; Grainger, Alan; Maniatis, Danae; Mollicone, Danilo; Moore, Rebecca; Patriarca, Chiara; Picard, Nicolas; Sparrow, Ben; Abraham, Elena Maria; Aloui, Kamel; Atesoglu, Ayhan; Attore, Fabio; Bassüllü, Çağlar; Bey, Adia; Garzuglia, Monica; García-Montero, Luis G; Groot, Nikée; Guerin, Greg; Laestadius, Lars; Lowe, Andrew J; Mamane, Bako; Marchi, Giulio; Patterson, Paul; Rezende, Marcelo; Ricci, Stefano; Salcedo, Ignacio; Diaz, Alfonso Sanchez-Paus; Stolle, Fred; Surappaeva, Venera; Castro, Rene

    2017-05-12

    Dryland biomes cover two-fifths of Earth's land surface, but their forest area is poorly known. Here, we report an estimate of global forest extent in dryland biomes, based on analyzing more than 210,000 0.5-hectare sample plots through a photo-interpretation approach using large databases of satellite imagery at (i) very high spatial resolution and (ii) very high temporal resolution, which are available through the Google Earth platform. We show that in 2015, 1327 million hectares of drylands had more than 10% tree-cover, and 1079 million hectares comprised forest. Our estimate is 40 to 47% higher than previous estimates, corresponding to 467 million hectares of forest that have never been reported before. This increases current estimates of global forest cover by at least 9%. Copyright © 2017, American Association for the Advancement of Science.

  15. Downstream extent of the N Reactor plume

    SciTech Connect

    Dauble, D.D.; Ecker, R.M.; Vail, L.W.; Neitzel, D.A.

    1987-09-01

    The downstream extent of the N Reactor thermal plume was studied to assess the potential for fisheries impacts downstream of N Reactor. The N Reactor plume, as defined by the 0.5/sup 0/F isotherm, will extend less than 10 miles downstream at river flows greater than or equal to annual average flows (120,000 cfs). Incremental temperature increases at the Oregon-Washington border are expected to be less than 0.5/sup 0/F during all Columbia River flows greater than the minimum regulated flows (36,000 cfs). The major physical factor affecting Columbia River temperatures in the Hanford Reach is solar radiation. Because the estimated temperature increase resulting from N Reactor operations is less than 0.3/sup 0/F under all flow scenarios, it is unlikely that Columbia River fish populations will be adversely impacted.

  16. Rate and extent of Helicobacter pylori phagocytosis.

    PubMed

    Allen, Lee-Ann H

    2008-01-01

    Helicobacter pylori is a Gram-negative bacterium that colonizes the gastric epithelium and plays a causative role in the development of peptic ulcers and gastric cancer. Phagocytosis is an element of innate defense used by macrophages and neutrophils to engulf microorganisms. We and others have shown that strains of H. pylori that contain the cag pathogenicity island actively retard their entry into phagocytes. Consequently, there is a lag of several minutes between bacterial binding and the onset of engulfment, and relative to other particles and microbes, the rate of internalization is slow. Herein, we describe in detail the use of synchronized phagocytosis and indirect immunofluorescence microscopy to quantify the rate and extent of H. pylori phagocytosis. This method is appropriate for primary phagocytes as well as transformed cell lines. More importantly, the effects of opsonins, virulence factors, and other agents on infection can be measured independent of bacterial viability or intracellular locale.

  17. The effect of non-uniform bending deformation on the stability of circumferential growth of through-wall cracks in brass tubes

    NASA Astrophysics Data System (ADS)

    Smith, E.; Wilding, M. J.

    EXPERIMENTAL results on the stability of circumferential growth of through-wall cracks in brass tubes, show that non-uniform bending can adversely affect the crack stability criterion. The results are relevant to the important technological problem of crack stability in 304 stainless steel pipes used in Boiling Water Reactors.

  18. Relation of midwall circumferential systolic stress to equatorial midwall fibre shortening in chronic aortic regurgitation. Value as a predictor of postoperative outcome.

    PubMed Central

    Almeida, P; Córdoba, M; Goicolea, J; Hernández Antolín, R; Rico, L A; Rey, M; Rábago, P; Rábago, G

    1984-01-01

    Nineteen patients with chronic aortic regurgitation and a large increase in heart size were studied before aortic valve replacement. By relating midwall circumferential systolic stress to midwall circumferential fibre shortening (Cs/Cd) before operation the patients could be divided into two well defined groups. Twelve patients (group 1) had a pronounced decrease in heart size as measured by the cardiothoracic ratio and an excellent clinical outcome six months after operation. Seven patients (group 2) had no significant decrease in heart size and a less good clinical outcome. The ratio of midwall circumferential systolic stress to end systolic volume index was significantly higher in group 1 than in group 2. Group 2 had more severe left ventricular hypertrophy determined by the ratio of the wall thickness to the minor internal radius of the left ventricle (h:r ratio), total left ventricular mass, and left ventricular mass to end diastolic volume ratio. There were no significant differences in any other haemodynamic or angiographic indices between the two groups. Thus the relation of midwall circumferential systolic stress to fibre shortening is useful in determining the prognosis in individual patients with chronic aortic regurgitation undergoing aortic valve replacement. PMID:6235830

  19. An Experimental Study on the Ultimate Strength of the Adventitia and Media of Human Atherosclerotic Carotid Arteries in Circumferential and Axial Directions

    PubMed Central

    Teng, Zhongzhao; Tang, Dalin; Zheng, Jie; Woodard, Pamela K.; Hoffman, Allen H.

    2009-01-01

    Atherosclerotic plaque may rupture without warning causing heart attack or stroke. Knowledge of the ultimate strength of human atherosclerotic tissues is essential for understanding the rupture mechanism and predicting cardiovascular events. Despite its great importance, experimental data on ultimate strength of human atherosclerotic carotid artery remains very sparse. This study determined the uniaxial tensile strength of human carotid artery sections containing type II and III lesions (AHA classifications). Axial and circumferential oriented adventitia, media and intact specimens (total=73) were prepared from 6 arteries. The ultimate strength in uniaxial tension was taken as the peak stress recorded when the specimen showed the first evidence of failure and the extensibility was taken as the stretch ratio at failure. The mean adventitia strength values calculated using the 1st Piola-Kirchoff stress were 1996±867kPa and 1802±703kPa in the axial and circumferential directions respectively, while the corresponding values for the media sections were 519±270kPa and 1230±533kPa. The intact specimens showed ultimate strengths similar to media in circumferential direction but were twice as strong as the media in the axial direction. Results also indicated that adventitia, media and intact specimens exhibited similar extensibility at failure, in both the axial and circumferential directions (stretch ratio 1.50 +/−0.22). These measurements of the material strength limits for human atherosclerotic carotid arteries could be useful in improving computational models that assess plaque vulnerability. PMID:19665126

  20. Improvement in pump function with endocardial biventricular pacing increases with activation time at the left ventricular pacing site in failing canine hearts.

    PubMed

    Howard, Elliot J; Covell, James W; Mulligan, Lawrence J; McCulloch, Andrew D; Omens, Jeffrey H; Kerckhoffs, Roy C P

    2011-10-01

    Recently, attention has been focused on comparing left ventricular (LV) endocardial (ENDO) with epicardial (EPI) pacing for cardiac resynchronization therapy. However, the effects of ENDO and EPI lead placement at multiple sites have not been studied in failing hearts. We hypothesized that differences in the improvement of ventricular function due to ENDO vs. EPI pacing in dyssynchronous (DYSS) heart failure may depend on the position of the LV lead in relation to the original activation pattern. In six nonfailing and six failing dogs, electrical DYSS was created by atrioventricular sequential pacing of the right ventricular apex. ENDO was compared with EPI biventricular pacing at five LV sites. In failing hearts, increases in the maximum rate of LV pressure change (dP/dt; r = 0.64), ejection fraction (r = 0.49), and minimum dP/dt (r = 0.51), relative to DYSS, were positively correlated (P < 0.01) with activation time at the LV pacing site during ENDO but not EPI pacing. ENDO pacing at sites with longer activation delays led to greater improvements in hemodynamic parameters and was associated with an overall reduction in electrical DYSS compared with EPI pacing (P < 0.05). These findings were qualitatively similar for nonfailing hearts. Improvement in hemodynamic function increased with activation time at the LV pacing site during ENDO but not EPI pacing. At the anterolateral wall, end-systolic transmural function was greater with local ENDO compared with EPI pacing. ENDO pacing and intrinsic activation delay may have important implications for management of DYSS heart failure.

  1. Diagnostic Accuracy of Endocardial-to-Epicardial Myocardial Blood Flow Ratio for the Detection of Significant Coronary Artery Disease With Dynamic Myocardial Perfusion Dual-Source Computed Tomography.

    PubMed

    Goto, Yoshitaka; Kitagawa, Kakuya; Uno, Mio; Nakamori, Shiro; Ito, Tatsuro; Nagasawa, Naoki; Dohi, Kaoru; Sakuma, Hajime

    2017-04-25

    Previous dynamic stress computed tomography perfusion (CTP) studies used absolute myocardial blood flow (MBF in mL/100 g/min) as a threshold to discriminate flow-limiting coronary artery disease (CAD), but absolute MBF can be vary because of multiple factors. The aim of this study was to compare the diagnostic performance of absolute MBF and the transmural perfusion ratio (TPR) for the detection of flow-limiting CAD, and to clarify the influence of CT delayed enhancement (CTDE) on the diagnostic performance of CTP.Methods and Results:We retrospectively enrolled 51 patients who underwent dual-source CTP and invasive coronary angiography (ICA). TPR was defined as the endocardial MBF of a specific segment divided by the mean of the epicardial MBF of all segments. Flow-limiting CAD was defined as luminal diameter stenosis >90% on ICA or a lesion with fractional flow reserve ≤0.8. Segmental presence and absence of myocardial scar was determined by CTDE. The area under the receiver-operating characteristics curve (AUC) of TPR was significantly greater than that of MBF for the detection of flow-limiting CAD (0.833 vs. 0.711, P=0.0273). Myocardial DE was present in 27 of the 51 patients and in 34 of 143 territories. When only territories containing DE were considered, the AUC of TPR decreased to 0.733. TPR calculated from absolute MBF demonstrated higher diagnostic performance for the discrimination of flow-limiting CAD when compared with absolute MBF itself.

  2. The May 2005 eruption of Fernandina volcano, Galápagos: The first circumferential dike intrusion observed by GPS and InSAR

    USGS Publications Warehouse

    Chadwick, W.W.; Jonsson, Sigurjon; Geist, Dennis J.; Poland, M.; Johnson, Daniel J.; Batt, S.; Harpp, Karen S.; Ruiz, A.

    2011-01-01

    The May 2005 eruption of Fernandina volcano, Galápagos, occurred along circumferential fissures parallel to the caldera rim and fed lava flows down the steep southwestern slope of the volcano for several weeks. This was the first circumferential dike intrusion ever observed by both InSAR and GPS measurements and thus provides an opportunity to determine the subsurface geometry of these enigmatic structures that are common on Galápagos volcanoes but are rare elsewhere. Pre- and post- eruption ground deformation between 2002 and 2006 can be modeled by the inflation of two separate magma reservoirs beneath the caldera: a shallow sill at ~1 km depth and a deeper point-source at ~5 km depth, and we infer that this system also existed at the time of the 2005 eruption. The co-eruption deformation is dominated by uplift near the 2005 eruptive fissures, superimposed on a broad subsidence centered on the caldera. Modeling of the co-eruption deformation was performed by including various combinations of planar dislocations to simulate the 2005 circumferential dike intrusion. We found that a single planar dike could not match both the InSAR and GPS data. Our best-fit model includes three planar dikes connected along hinge lines to simulate a curved concave shell that is steeply dipping (~45–60°) toward the caldera at the surface and more gently dipping (~12–14°) at depth where it connects to the horizontal sub-caldera sill. The shallow sill is underlain by the deep point source. The geometry of this modeled magmatic system is consistent with the petrology of Fernandina lavas, which suggest that circumferential eruptions tap the shallowest parts of the system, whereas radial eruptions are fed from deeper levels. The recent history of eruptions at Fernandina is also consistent with the idea that circumferential and radial intrusions are sometimes in a stress-feedback relationship and alternate in time with one another.

  3. Significance of mechanical alterations in single ventricle patients on twisting and circumferential strain as determined by analysis of strain from gradient cine magnetic resonance imaging sequences.

    PubMed

    Truong, Uyen T; Li, Xiaokui; Broberg, Craig S; Houle, Helene; Schaal, Michael; Ashraf, Muhammad; Kilner, Philip; Sheehan, Florence H; Sable, Craig A; Ge, Shuping; Sahn, David J

    2010-05-15

    Preliminary speckle-tracking echocardiographic studies show that patients with single ventricles (SVs) have significantly decreased twisting and dyssynchrony of twisting. This could be related to abnormal cardiac looping, which leads to hearts that lack helical fiber patterns. The aim of this study was to analyze gradient cine magnetic resonance imaging (MRI) using Velocity Vector Imaging to assess cardiac mechanics. Subjects were 38 patients (aged 8 to 37 years) with SVs of left ventricular (n = 30) and indeterminate (n = 8) type who underwent cardiac MRI. Controls were 14 normal children and adults. Gradient cine MRI sequences close to the apex were subjected to a Velocity Vector Imaging analysis program adapted for MRI. In the control group, mean circumferential strain was -18.02 +/- 7.31%, mean dispersion of peak circumferential strain was 44.23 +/- 37.14 ms, and average rotation was -7.7 +/- 1.38 degrees . The rotation values were negative, or counterclockwise. In patients with SVs, mean circumferential strain was -8.87 +/- 7.30%, mean dispersion of peak circumferential strain was 181.55 +/- 76.07 ms, and average rotation was -2.6 +/- 1.24 degrees (p <0.001). Mean dispersion of the peak of rotation in the control group was 39.6 +/- 22.8 ms, compared to 166.5 +/- 72.4 ms in patients with SVs. In conclusion, this study showed a dramatic decrease in apical rotation and circumferential strain in the SV group compared to the control group. Strain and rotation mechanics at the apex in patients with SVs showed marked dyssynchrony. Copyright 2010 Elsevier Inc. All rights reserved.

  4. The extent of the local hi halo

    NASA Technical Reports Server (NTRS)

    Lockman, F. J.; Hobbs, L. M.; Shull, J. M.

    1985-01-01

    Forty-five high-latitude, OB stars have been observed in the Ly alpha and 21 cm lines of HI in an effort to map out the vertical distribution and extent of the local HI halo. The 25 stars for which a reliable HI colum density can be obtained from Ly alpha lie between 60 and 3100 pc from the plane. The principal result is that the total column density of HI at z 1 kpc is, on the average, 5 + or - 3 x 10 the 19th power/sq cm, or 15% of the total sub HI. At relatively low z the data toward some stars suggest a low effective scale height and fairly high average foreground density, while toward others the effective scale height is large and the average density is low. This can be understood as the result of irregularities in the interstellar medium. A model with half of the HI mass in clouds having radii of a few pc and a Gaussian vertical distribution with sigma sub 2 = 135 pc, and half of the mass in an exponential component with a scale height of 500 pc, gives a satisfactory fit to the data. The technique of comparing Ly alpha and 21 cm column densities is also used to discuss the problem of estimating the distance to several possibly subluminous stars.

  5. What is the extent of prokaryotic diversity?

    PubMed

    Curtis, Thomas P; Head, Ian M; Lunn, Mary; Woodcock, Stephen; Schloss, Patrick D; Sloan, William T

    2006-11-29

    The extent of microbial diversity is an intrinsically fascinating subject of profound practical importance. The term 'diversity' may allude to the number of taxa or species richness as well as their relative abundance. There is uncertainty about both, primarily because sample sizes are too small. Non-parametric diversity estimators make gross underestimates if used with small sample sizes on unevenly distributed communities. One can make richness estimates over many scales using small samples by assuming a species/taxa-abundance distribution. However, no one knows what the underlying taxa-abundance distributions are for bacterial communities. Latterly, diversity has been estimated by fitting data from gene clone libraries and extrapolating from this to taxa-abundance curves to estimate richness. However, since sample sizes are small, we cannot be sure that such samples are representative of the community from which they were drawn. It is however possible to formulate, and calibrate, models that predict the diversity of local communities and of samples drawn from that local community. The calibration of such models suggests that migration rates are small and decrease as the community gets larger. The preliminary predictions of the model are qualitatively consistent with the patterns seen in clone libraries in 'real life'. The validation of this model is also confounded by small sample sizes. However, if such models were properly validated, they could form invaluable tools for the prediction of microbial diversity and a basis for the systematic exploration of microbial diversity on the planet.

  6. Combined Circumferential and Longitudinal Left Ventricular Systolic Dysfunction in Patients with Rheumatoid Arthritis without Overt Cardiac Disease.

    PubMed

    Cioffi, Giovanni; Viapiana, Ombretta; Ognibeni, Federica; Dalbeni, Andrea; Gatti, Davide; Mazzone, Carmine; Faganello, Giorgio; Di Lenarda, Andrea; Adami, Silvano; Rossini, Maurizio

    2016-07-01

    Patients with rheumatoid arthritis have an increased risk for cardiovascular disease. Because of accelerated atherosclerosis and changes in left ventricular (LV) geometry, circumferential and longitudinal (C&L) LV systolic dysfunction (LVSD) may be impaired in these patients despite preserved LV ejection fraction. The aim of this study was to determine the prevalence of and factors associated with combined C&L LVSD in patients with rheumatoid arthritis. One hundred ninety-eight outpatients with rheumatoid arthritis without overt cardiac disease were prospectively analyzed from January through June 2014 and compared with 198 matched control subjects. C&L systolic function was evaluated by stress-corrected midwall shortening (sc-MS) and tissue Doppler mitral annular peak systolic velocity (S'). Combined C&L LVSD was defined if sc-MS was <86.5% and S' was <9.0 cm/sec (the 10th percentiles of sc-MS and S' derived in 132 healthy subjects). Combined C&L LVSD was detected in 56 patients (28%) and was associated with LV mass (odds ratio, 1.03; 95% CI, 1.01-1.06; P = .04) and concentric LV geometry (odds ratio, 2.76; 95% CI, 1.07-7.15; P = .03). By multiple logistic regression analysis, rheumatoid arthritis emerged as an independent predictor of combined C&L LVSD (odds ratio, 2.57; 95% CI, 1.06-6.25). The relationship between sc-MS and S' was statistically significant in the subgroup of 142 patients without combined C&L LVSD (r = 0.40, F < 0.001), having the best fitting by a linear function (sc-MS = 58.1 + 3.34 × peak S'; r(2) = 0.19, P < .0001), absent in patients with combined C&L LVSD. Combined C&L LVSD is detectable in about one fourth of patients with asymptomatic rheumatoid arthritis and is associated with LV concentric remodeling and hypertrophy. Rheumatoid arthritis predicts this worrisome condition, which may explain the increased risk for cardiovascular events in these patients. The aim of this "notice of clarification" is to analyze in brief

  7. Circumferential Reconstruction of Subaxial Cervical and Cervicothoracic Spine by Simultaneously Combined Anterior-posterior Approaches in the Sitting Position.

    PubMed

    Han, Yue; Ma, Xin-Long; Hu, Yong-Cheng; Miao, Jun; Zhang, Ji-Dong; Bai, Jian-Qiang; Xia, Qun

    2017-08-01

    To introduce and analyze the feasibility of a new surgical strategy for circumferential reconstruction of subaxial cervical and cervicothoracic spine by simultaneously combined anterior-posterior approach in the sitting position. A retrospective review was performed for seven patients who underwent the above surgical procedure between July 2011 and January 2015. Among the seven patients, there were six men and one woman, with an average age of 52 years (range, 36-79 years). Six patients were confirmed to have a lower subaxial cervical fracture and dislocation with a locked facet joint, and the other patient had an invasive tumor involving both anterior and posterior parts of vertebrae and lamina, detected by radiological examination. The levels involved for all patients were from C4 to T2 . According to American Spinal Injury Association (ASIA) classification, one case was class A, four were class B, and two were class D. The patients were restricted in the sitting position with traction and a halo in extension to immobilize the head during the operation. The simultaneously combined anterior-posterior operation for reduction, decompression or tumor resection and circumferential reconstruction was carried out. Both anterior and posterior procedures were successfully completed simultaneously in the sitting position in all cases. There were no perioperative complications. The average operative time was 175 ± 32 min (range, 120-240 min), and the mean blood loss was 430 ± 85 mL (range, 200-1100 mL). The patients were followed up for 35.8 months (range, 18-60 months). The symptom of neck pain improved distinctly and no evidence of implant failure was noted in any patients. Neurological status improvement was confirmed in six patients, who had suffered incomplete paralysis. The ASIA grade improved in five patients, and two cases had no change in grade. The "sitting position" simultaneously combined anterior-posterior approach is safe and is

  8. The distribution and extent of lunar swirls

    NASA Astrophysics Data System (ADS)

    Denevi, Brett W.; Robinson, Mark S.; Boyd, Aaron K.; Blewett, David T.; Klima, Rachel L.

    2016-07-01

    The mysterious high-reflectance loops and ribbons known as swirls are not uncommon on the Moon, but are apparently unique to this body. We mapped their distribution and extent using ultraviolet-visible images from the Lunar Reconnaissance Orbiter Camera. We find two main geographic groupings of swirls (South Pole-Aitken Basin and Marginis-King) and a host of smaller features including swirls near craters Abel, Crozier, Dewar, and Dufay X. All mapped swirls are associated with magnetic anomalies and swirls have magnetic field strengths shifted to higher values than their background, though there is not a 1:1 correspondence between the locations of swirls and magnetic anomalies. Swirls are also found in regions with iron abundances shifted to higher-than-background values, which could indicate that their formation is inhibited by low iron content. The most distinguishing characteristic of swirls is a low 321/415 nm ratio coupled with moderate to high reflectance, and swirls generally have high optical maturity (OMAT) parameter values, stronger 1-μm bands, and shallower normalized continuum slopes than their surroundings, consistent with a surface that has experienced less space weathering. However, some swirls cannot be discerned in OMAT or band-depth images. Areas with low 321/415 nm ratios but non-distinct visible-near-infrared properties could be related to the presence of fresh silicates or a glassy component that does not have a substantial abundance of embedded large submicroscopic iron grains (i.e., a difference in the agglutinate fraction of the soil). Swirl color properties vary with distance from Copernican and some Eratosthenian craters; their association with Eratostheninan craters suggests fresh material may be preserved longer in swirls than in non-swirl regions.

  9. Circumferential suction-assisted lipectomy in the treatment of primary and secondary end-stage lymphoedema of the leg.

    PubMed

    Lamprou, D-A A; Voesten, H G J; Damstra, R J; Wikkeling, O R M

    2017-01-01

    The treatment of end-stage lymphoedema of the leg is challenging, especially when conservative treatment fails and there is a large volume difference between the affected and unaffected legs. Circumferential suction-assisted lipectomy (CSAL) has been described as a treatment option for end-stage lymphoedema of the leg. Here, the long-term results of CSAL in end-stage primary and secondary lymphoedema of the leg were analysed. This was a descriptive study of patients treated with CSAL for unilateral chronic irreversible lymphoedema of the leg. Compression therapy was resumed after surgery. Leg volumes were measured before surgery, and at 1, 6, 12 and 24 months after the procedure. A total of 47 patients with primary lymphoedema had a median preoperative volume difference between affected and unaffected legs of 3686 (i.q.r. 2851-5121) ml. Two years after surgery, this volume difference was reduced to 761 ml, a 79 per cent reduction. In the 41 patients treated for secondary lymphoedema, the median preoperative volume difference was 3320 (i.q.r. 2533-4783) ml, decreasing after 2 years to -38 ml (101 per cent reduction). The preoperative volume difference and the sex of the patient significantly influenced the final outcome after 2 years. The outcome was not related to BMI or other patient characteristics. CSAL is an effective method for treating both primary and secondary lymphoedema of the leg. © 2016 BJS Society Ltd Published by John Wiley & Sons Ltd.

  10. [Radiofrequency ablation in the treatment of focal atrial fibrillation using circumferential mapping and segmentary disconnection of pulmonary veins].

    PubMed

    Silva, Rose M F L; Mont, Lluís; Berruezo, Antonio; Fosch, Xavier; Wayar, Luis; Alvarenga, Nelson; Chueca, Enrique; Brugada, Josep

    2003-04-01

    The treatment of paroxysmal atrial fibrillation in patients without structural heart disease using radiofrequency ablation of pulmonary veins is a recently developed procedure with a good clinical success rate, although there have only been a few published series. We analyzed our results with this technique. The procedure was performed in 33 highly symptomatic patients with focal atrial fibrillation that had probably originated in the pulmonary veins. The electrophysiological study was carried out with a decapolar catheter inserted by transeptal catheterization. Ablation was performed using a 4-mm catheter and directed to the segments of the ostium of pulmonary veins where venous potentials with greatest precocity were recorded. Subsequent radiofrecuency applications were performed until pulmonary vein disconnection was achieved. Venous electrical activity was recorded in 59 of 115 pulmonary veins that were mapped (58 were disconnected). During a median follow-up of 180 days, 8 patients recurred and only 2 of these continue with repeat episodes. The success rate at short term was 74.2% and at mid-term was 93.5%. Nineteen patients continue to receive antiarrhythmic treatment innefective before the procedure. Two patients showed complications related to catheter manipulation during tansseptal catheterization, probably due to air embolism, that was resolved spontaneously without consequences. No patient showed pulmonary stenosis. Teatment of focal atrial fibrillation using circumferential mapping and radiofrecuency application in segments of the ostium of pulmonary veins is a highly effective procedure in selected patients and has potentially severe although infrequent complications.

  11. Circumferential suction lipectomy of the trunk with anterior rectus fascia plication through a periumbilical incision: an alternative to conventional abdominoplasty.

    PubMed

    Dabb, Richard W; Hall, Wesley W; Baroody, Michael; Saba, Amer A

    2004-02-01

    During the past decade, many combinations of operative techniques for abdominoplasty have evolved to suit the individual requirements of the patient. The purpose of this study was to present a safe alternative to conventional abdominoplasty for appropriate patients, namely, those with minimal skin laxity, moderate fatty tissue distribution, musculofascial diastases, and no concern for abdominal stretch marks. The procedure consists of circumferential ultrasound-assisted liposuction and direct abdominal wall plication through a periumbilical incision. Thirty-two patients were evaluated on overall patient satisfaction and complication rates, including seroma (five, 15.6 percent), major sensory loss (none), skin slough (none), skin burns (none), end hits (i.e., a small, partial-thickness, subdermal burn; one, 3 percent), and limited results (two, 6 percent). The patients expressed that avoidance of the abdominal scar and diminished recuperative time outweighed the benefit of tighter skin associated with conventional abdominoplasty. This technique may provide another avenue for appropriate contouring of the abdomen in properly selected patients.

  12. Management of complicated chronic anal fissures with high-dose circumferential chemodenervation (HDCC) of the internal anal sphincter.

    PubMed

    Whatley, James Z; Tang, Shou-Jiang; Glover, Porter H; Davis, Eric D; Jex, Kellen T; Wu, Ruonan; Lahr, Christopher J

    2015-12-01

    Botulinum toxin injection into the internal anal sphincter (IAS) is gaining popularity as a second line therapy for chronic anal fissures after patients fail medical therapy. The dosage of Botulinum toxin reported in the literature ranged from 20 to 50 IU. Complicated chronic anal fissure is defined as persistent fissure concurrent with other perianal pathology. We report a new approach involving high-dose circumferential chemodenervation (HDCC) of 100 IU in treating these complicated chronic anal fissures. The aim of this study was to evaluate the fissure healing, complication, and recurrence rates with HDCC. Complicated anal fissure was defined as fissure with other perianal pathologies including skin tag, hypertrophied papilla, fistula, symptomatic hemorrhoids, anal condylomata, and abscess. Between 2008 and 2012, 62 consecutive patients (28 Blacks, 33 Whites, 1 Hispanic) with complete follow-up data were included in this single arm study. These patients underwent HDCC-IAS with addition interventions by a single colorectal surgeon. Follow up data were obtained by chart review and office follow up. Of the 62 patients, the overall success rate was greater than 70% at 3 months follow-up. A few patients developed transient flatus or fecal incontinence, but shortly resolved. There was no major complication following HDCC-IAS. Combination therapy involving HDCC-IAS and local anorectal surgery for associated condition is both safe and effective for fissure healing. Copyright © 2015 IJS Publishing Group Limited. Published by Elsevier Ltd. All rights reserved.

  13. Wall thickness measurement using resonant phenomena of circumferential Lamb waves generated by plural transducer elements located evenly on girth

    NASA Astrophysics Data System (ADS)

    Nishino, Hideo; Iwata, Kodai; Ishikawa, Masashi

    2016-07-01

    We present a novel method of measuring the pipe wall thickness using the resonance of the circumferential (C-) Lamb wave generated by a piezoelectric ring-shaped sensor (PS). The PS is a special device for an axially propagating torsional wave; however, the C-Lamb waves are generated simultaneously as spurious signals owing to the structure of the PS. Particularly under resonant conditions, the C-Lamb waves are dominantly generated, distorting the axially propagating wave. In this method, these troublesome spurious signals are used effectively for the measurement of the wall thickness under the PS location that is a dead zone of the PS itself. The method can compensate for its drawback, namely, the dead zone problem, without using additional instruments. In this study, the mechanisms of the generation and resonance of the C-Lamb waves were first explained. Secondly, the principle of the wall thickness estimation utilizing the resonance of the C-Lamb waves was proposed. Finally, experimental verifications were carried out. The estimated wall thicknesses agreed very well (maximum 1.5% error) with those measured by a micrometer caliper under suitable resonant conditions.

  14. Contribution to the leak before break behavior of piping made of high tough material and containing circumferential flaws

    SciTech Connect

    Stadtmueller, W.; Sturm, D.

    1996-12-31

    Since 1993 MPA Stuttgart is engaged in two new research projects in the field of Leak-Before-Break (LBB) behavior of austenitic piping. The pipes are fabricated in the dimensions O.D. {times} t = 219 x 14 mm resp. 331 x 32 mm and prepared with fatigue precracked, circumferential flaws of various depth and up to a crack length equivalent to 2{alpha} = 270 deg. The flaw location is in the base material or in site-made girth welds. The pipes are loaded with internal pressure and external bending moment at room temperature. In this paper the results of the tested pipes with 219 mm diameter containing through-wall flaws are represented as a comparison with the results of applied analytical methods. On these pipes the crack initiation clearly occurred before maximum bending moment, which was attained under full yielding conditions even in case of the 180 deg through-wall flaw. With the applied analytical methods crack initiation as well as maximum load could be assessed in a realistic manner.

  15. Evaluation of the novel combination of daptomycin plus ceftriaxone against vancomycin-resistant enterococci in an in vitro pharmacokinetic/pharmacodynamic simulated endocardial vegetation model.

    PubMed

    Hall Snyder, Ashley; Werth, Brian J; Barber, Katie E; Sakoulas, George; Rybak, Michael J

    2014-08-01

    Daptomycin has demonstrated synergy with β-lactams against Enterococcus faecium and this combination has been used successfully to treat infections refractory to daptomycin. We investigated daptomycin alone and combined with ceftriaxone against vancomycin-resistant enterococci (VRE) in an in vitro pharmacokinetic/pharmacodynamic simulated endocardial vegetation (SEV) model. Daptomycin (6 and 12 mg/kg/day) with and without 2 g of ceftriaxone every 24 h were evaluated against two clinical E. faecium strains (8019 and 5938) and one Enterococcus faecalis (6981) in a 96 h in vitro pharmacokinetic/pharmacodynamic SEV model. FITC-labelled poly-l-lysine was used to assess β-lactam-induced changes in cell surface charge. For 8019 and 6981, daptomycin 6 mg/kg with ceftriaxone and daptomycin 12 mg/kg alone and in combination with ceftriaxone displayed significantly more activity than daptomycin 6 mg/kg alone from 48 to 96 h (P ≤ 0.005). The addition of ceftriaxone significantly enhanced activity of daptomycin 6 mg/kg against both strains at 96 h (8019, reductions -0.55 versus 3.64 log10 cfu/g; 6981, reductions 1.11 versus 5.67 log10 cfu/g; P < 0.001) and improved daptomycin 12 mg/kg against 8019 at 96 h. Daptomycin 12 mg/kg plus ceftriaxone displayed no appreciable activity against 5938 (daptomycin MIC 32 mg/L). Daptomycin non-susceptibility developed in 8019 and 6981 versus daptomycin 6 mg/kg by 96 h. Ampicillin or ceftriaxone exposure reduced daptomycin surface charge in 8019, resulting in significantly increased FITC-poly-l-lysine binding. The combination of daptomycin and ceftriaxone may be promising for eradicating high-inoculum, deep-seated enterococcal infections. Further research is warranted to examine the enhancement of daptomycin and innate immunity killing of VRE by ceftriaxone and other β-lactams. © The Author 2014. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For

  16. Zero-fluoroscopy cryothermal ablation of atrioventricular nodal reentry tachycardia guided by endovascular and endocardial catheter visualization using intracardiac echocardiography (Ice&ICE Trial).

    PubMed

    Luani, Blerim; Zrenner, Bernhard; Basho, Maksim; Genz, Conrad; Rauwolf, Thomas; Tanev, Ivan; Schmeisser, Alexander; Braun-Dullaeus, Rüdiger C

    2017-09-27

    Stochastic damage of the ionizing radiation to both patients and medical staff is a drawback of fluoroscopic guidance during catheter ablation of cardiac arrhythmias. Therefore, emerging zero-fluoroscopy catheter-guidance techniques are of great interest. We investigated in a prospective pilot study the feasibility and safety of the cryothermal (CA) slow-pathway ablation in patients with symptomatic atrioventricular-nodal-reentry-tachycardia (AVNRT) using solely intracardiac echocardiography (ICE) for endovascular and endocardial catheter visualization. Twenty-five consecutive patients (mean age 55.6±12.0 years, 17 female) with ECG-documentation or symptoms suggesting AVNRT underwent an electrophysiology study (EPS) in our laboratory utilizing ICE for catheter navigation. Supraventricular tachycardia was inducible in 23 (92%) patients; AVNRT was confirmed by appropriate stimulation maneuvers in 20 (80%) patients. All EPS in the AVNRT subgroup could be accomplished without need for fluoroscopy, relying solely on ICE-guidance. CA guided by anatomical location and slow-pathway potentials was successful in all patients, median cryo-mappings = 6 (IQR:3-10), median cryo-ablations = 2 (IQR:1-3). Fluoroscopy was used to facilitate the transseptal puncture and localization of the ablation substrate in the remaining 3 patients (one focal atrial tachycardia and 2 atrioventricular-reentry-tachycardias). Mean EPS duration in the AVNRT subgroup was 99.8±39.6 min, ICE guided catheter placement 11.9±5.8 min, time needed for diagnostic evaluation 27.1±10.8 min and cryo-application duration 26.3±30.8 min. ICE-guided zero-fluoroscopy CA in AVNRT patients is feasible and safe. Real-time visualization of the true endovascular borders and cardiac structures allow for safe catheter navigation during the ICE-guided EPS and might be an alternative to visualization technologies using geometry reconstructions. This article is protected by copyright. All rights reserved. This

  17. Influence of circumferential notch and fatigue crack on the mechanical integrity of biodegradable magnesium-based alloy in simulated body fluid.

    PubMed

    Bobby Kannan, M; Singh Raman, R K; Witte, F; Blawert, C; Dietzel, W

    2011-02-01

    Applications of magnesium alloys as biodegradable orthopaedic implants are critically dependent on the mechanical integrity of the implant during service. In this study, the mechanical integrity of an AZ91 magnesium alloy was studied using a constant extension rate tensile (CERT) method. The samples in two different geometries that is, circumferentially notched (CN), and circumferentially notched and fatigue cracked (CNFC), were tested in air and in simulated body fluid (SBF). The test results show that the mechanical integrity of the AZ91 magnesium alloy decreased substantially (∼50%) in both the CN and CNFC samples exposed to SBF. Fracture surface analysis revealed secondary cracks suggesting stress corrosion cracking susceptibility of the alloy in SBF.

  18. Propagation and radiation of sound from flanged circular ducts with circumferentially varying wall admittances. I Semi-infinite ducts. II - Finite ducts with sources

    NASA Technical Reports Server (NTRS)

    Fuller, C. R.

    1984-01-01

    Sound propagation in infinite, semiinfinite, and finite circular ducts with circumferentially varying wall admittances is investigated analytically. The infinite case is considered, and an example demonstrates the effects of wall-admittance distribution on dispersion characteristics and mode shapes. An exact solution is obtained for the semiinfinite case, a circular duct with a flanged opening: sidelobe suppression and circumferential-mode energy scattering leading to radiated-field asymmetry are found. A finite duct system with specified hard-walled pressure sources is examined in detail, evaluating reflection coefficients, transmission losses, and radiated-field directivity. Graphs and diagrams are provided, and the implications of the results obtained for the design of aircraft-turbofan inlet liners are discussed.

  19. Method and Apparatus for Determining Changes in Intracranial Pressure Utilizing Measurement of the Circumferential Expansion or Contraction of a Patient's Skull

    NASA Technical Reports Server (NTRS)

    Yos, William T. (Inventor); Cantrell, John H., Jr. (Inventor)

    2004-01-01

    A method and apparatus for measuring changes in intracranial pressure (ICP) utilizing the variation of the surface wave propagation parameters of the patient's skull to determine the change in ICP. In one embodiment, the method comprises the steps of transmitting an ultrasonic bulk compressional wave onto the surface of the skull at a predetermined angle with respect to the skull so as to produce a surface wave, receiving the surface wave at an angle with respect tn the skull which is substantially the same as the predetermined angle and at a location that is a predetermined distance from where the ultrasonic bulk compressional wave was transmitted upon the skull, determining the retardation or advancement in phase of the received surface wave with respect to a reference phase, and processing the determined retardation or advancement in phase to determine circumferential expansion or contraction of the skull and utilizing the determined circumferential change to determine the change in intracranial pressure.

  20. Propagation and radiation of sound from flanged circular ducts with circumferentially varying wall admittances. I Semi-infinite ducts. II - Finite ducts with sources

    NASA Technical Reports Server (NTRS)

    Fuller, C. R.

    1984-01-01

    Sound propagation in infinite, semiinfinite, and finite circular ducts with circumferentially varying wall admittances is investigated analytically. The infinite case is considered, and an example demonstrates the effects of wall-admittance distribution on dispersion characteristics and mode shapes. An exact solution is obtained for the semiinfinite case, a circular duct with a flanged opening: sidelobe suppression and circumferential-mode energy scattering leading to radiated-field asymmetry are found. A finite duct system with specified hard-walled pressure sources is examined in detail, evaluating reflection coefficients, transmission losses, and radiated-field directivity. Graphs and diagrams are provided, and the implications of the results obtained for the design of aircraft-turbofan inlet liners are discussed.

  1. Blade row dynamic digital compression program. Volume 2: J85 circumferential distortion redistribution model, effect of Stator characteristics, and stage characteristics sensitivity study

    NASA Technical Reports Server (NTRS)

    Tesch, W. A.; Steenken, W. G.

    1978-01-01

    The results of dynamic digital blade row compressor model studies of a J85-13 engine are reported. The initial portion of the study was concerned with the calculation of the circumferential redistribution effects in the blade-free volumes forward and aft of the compression component. Although blade-free redistribution effects were estimated, no significant improvement over the parallel-compressor type solution in the prediction of total-pressure inlet distortion stability limit was obtained for the J85-13 engine. Further analysis was directed to identifying the rotor dynamic response to spatial circumferential distortions. Inclusion of the rotor dynamic response led to a considerable gain in the ability of the model to match the test data. The impact of variable stator loss on the prediction of the stability limit was evaluated. An assessment of measurement error on the derivation of the stage characteristics and predicted stability limit of the compressor was also performed.

  2. Flaw Inspection of Aluminum Pipes by Non-Contact Visualization of Circumferential Guided Waves using Laser Ultrasound Generation and an Air-Coupled Sensor

    NASA Astrophysics Data System (ADS)

    Urabe, K.; Takatsubo, J.; Toyama, N.; Yamamoto, T.; Tsuda, H.

    2014-06-01

    Our group had previously proposed a generation laser scanning system for visualizing ultrasound propagation on an object as an animate image, which provided visible and quick flaw inspection. Recently, we improved this system to make it completely non-contact by employing an air-coupled ultrasound transducer as a receiver instead of a contact transducer, and demonstrated the successful visualization of Lamb waves propagating on aluminum and carbon fiber reinforced plastic plates, as well as the detection of flaws. In this research, we applied this system to the non-contact visualization of circumferential guided waves on aluminum pipes. It was shown that circumferential guided waves propagating in opposite directions could be visualized separately, and that a flaw such as a slit or thinning on the inside surface of the pipe could be successfully detected even when it existed outside the scanning area.

  3. Ultrasound speckle tracking for radial, longitudinal and circumferential strain estimation of the carotid artery--an in vitro validation via sonomicrometry using clinical and high-frequency ultrasound.

    PubMed

    Larsson, Matilda; Heyde, Brecht; Kremer, Florence; Brodin, Lars-Åke; D'hooge, Jan

    2015-02-01

    Ultrasound speckle tracking for carotid strain assessment has in the past decade gained interest in studies of arterial stiffness and cardiovascular diseases. The aim of this study was to validate and directly contrast carotid strain assessment by speckle tracking applied on clinical and high-frequency ultrasound images in vitro. Four polyvinyl alcohol phantoms mimicking the carotid artery were constructed with different mechanical properties and connected to a pump generating carotid flow profiles. Gray-scale ultrasound long- and short-axis images of the phantoms were obtained using a standard clinical ultrasound system, Vivid 7 (GE Healthcare, Horten, Norway) and a high-frequency ultrasound system, Vevo 2100 (FUJIFILM, VisualSonics, Toronto, Canada) with linear-array transducers (12L/MS250). Radial, longitudinal and circumferential strains were estimated using an in-house speckle tracking algorithm and compared with reference strain acquired by sonomicrometry. Overall, the estimated strain corresponded well with the reference strain. The correlation between estimated peak strain in clinical ultrasound images and reference strain was 0.91 (p<0.001) for radial strain, 0.73 (p<0.001) for longitudinal strain and 0.90 (p<0.001) for circumferential strain and for high-frequency ultrasound images 0.95 (p<0.001) for radial strain, 0.93 (p<0.001) for longitudinal strain and 0.90 (p<0.001) for circumferential strain. A significant larger bias and root mean square error was found for circumferential strain estimation on clinical ultrasound images compared to high frequency ultrasound images, but no significant difference in bias and root mean square error was found for radial and longitudinal strain when comparing estimation on clinical and high-frequency ultrasound images. The agreement between sonomicrometry and speckle tracking demonstrates that carotid strain assessment by ultrasound speckle tracking is feasible.

  4. Effects of Residual Stress, Axial Stretch, and Circumferential Shrinkage on Coronary Plaque Stress and Strain Calculations: A Modeling Study Using IVUS-Based Near-Idealized Geometries.

    PubMed

    Wang, Liang; Zhu, Jian; Samady, Habib; Monoly, David; Zheng, Jie; Guo, Xiaoya; Maehara, Akiko; Yang, Chun; Ma, Genshan; Mintz, Gary S; Tang, Dalin

    2017-01-01

    Accurate stress and strain calculations are important for plaque progression and vulnerability assessment. Models based on in vivo data often need to form geometries with zero-stress/strain conditions. The goal of this paper is to use IVUS-based near-idealized geometries and introduce a three-step model construction process to include residual stress, axial shrinkage, and circumferential shrinkage and investigate their impacts on stress and strain calculations. In Vivo intravascular ultrasound (IVUS) data of human coronary were acquired for model construction. In Vivo IVUS movie data were acquired and used to determine patient-specific material parameter values. A three-step modeling procedure was used to make our model: (a) wrap the zero-stress vessel sector to obtain the residual stress; (b) stretch the vessel axially to its length in vivo; and (c) pressurize the vessel to recover its in vivo geometry. Eight models were constructed for our investigation. Wrapping led to reduced lumen and cap stress and increased out boundary stress. The model with axial stretch, circumferential shrink, but no wrapping overestimated lumen and cap stress by 182% and 448%, respectively. The model with wrapping, circumferential shrink, but no axial stretch predicted average lumen stress and cap stress as 0.76 kPa and -15 kPa. The same model with 10% axial stretch had 42.53 kPa lumen stress and 29.0 kPa cap stress, respectively. Skipping circumferential shrinkage leads to overexpansion of the vessel and incorrect stress/strain calculations. Vessel stiffness increase (100%) leads to 75% lumen stress increase and 102% cap stress increase.

  5. High-dose circumferential chemodenervation of the internal anal sphincter: A new treatment modality for uncomplicated chronic anal fissure: A retrospective cohort study (with video).

    PubMed

    Glover, Porter H; Tang, Shou-jiang; Whatley, James Z; Davis, Eric D; Jex, Kellen T; Wu, Ruonan; Lahr, Christopher J

    2015-11-01

    Botulinum toxin injection into the internal anal sphincter is gaining popularity as a second line therapy for chronic anal fissures if medical therapy fails. The dosage of botulinum toxin reported ranged from 20 to 50 IU with no more than 3 injection sites and results in a healing rate of 41%-88% at 3 months. We propose a new injection method of high-dose circumferential chemodenervation of 100 IU in treating chronic anal fissure. This was a retrospective review at a single academic center. 75 patients (50 women and 25 men) with uncomplicated chronic anal fissures underwent high-dose circumferential chemodenervation-internal anal sphincter (100 IU). We measured fissure healing, complication, and recurrence rates at 3 and 6 months post injection. Of the 75 patients, healing rate was 90.7% at 3 months follow up with the first injection and 81.3% with the second injection. The recurrence rates were 20.6% and 12.5% at 6 months after the 1st and 2nd injections respectively. Excluding 5 patients who lost follow up, the total healing rate of the study cohort was 100%. At 2 weeks and 3 months, there were no major complications including hematoma, infection, flatus, fecal, and urinary incontinence. High-dose circumferential chemodenervation-internal anal sphincter (100 IU) is a safe and effective method for uncomplicated chronic anal fissure. Copyright © 2015 IJS Publishing Group Limited. Published by Elsevier Ltd. All rights reserved.

  6. 46 CFR 172.235 - Extent of damage.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... is less. Transverse extent 4 feet 2 inches (1.25 m).1 Vertical extent From the baseline upward...), whichever is less, but not less than 16.4 feet (5 m).1 Vertical extent 0.75 m from the baseline. Grounding.... Transverse 4 feet 2 inches (1.25 m). Vertical extent 2 feet 6 inches (0.75 m) from the baseline. 1 Damage...

  7. Sparing Sphincters and Laparoscopic Resection Improve Survival by Optimizing the Circumferential Resection Margin in Rectal Cancer Patients

    PubMed Central

    Keskin, Metin; Bayraktar, Adem; Sivirikoz, Emre; Yegen, Gülcin; Karip, Bora; Saglam, Esra; Bulut, Mehmet Türker; Balik, Emre

    2016-01-01

    Abstract The goal of rectal cancer treatment is to minimize the local recurrence rate and extend the disease-free survival period and survival. For this aim, obtainment of negative circumferential radial margin (CRM) plays an important role. This study evaluated predictive factors for positive CRM status and its effect on patient survival in mid- and distal rectal tumors. Patients who underwent curative resection for rectal cancer were included. The main factors were demographic data, tumor location, surgical technique, neoadjuvant therapy, tumor diameter, tumor depth, lymph node metastasis, mesorectal integrity, CRM, the rate of local recurrence, distant metastasis, and overall and disease-free survival. Statistical analyses were performed by using the Chi-squared test, Fisher exact test, Student t test, Mann–Whitney U test and the Mantel–Cox log-rank sum test. A total of 420 patients were included, 232 (55%) of whom were male. We observed no significant differences in patient characteristics or surgical treatment between the patients who had positive CRM and who had negative CRM, but a higher positive CRM rate was observed in patients undergone abdominoperineal resection (APR) (P < 0.001). Advanced T-stage (P < 0.001), lymph node invasion (P = 0.001) and incomplete mesorectum (P = 0.007) were encountered significantly more often in patients with positive CRM status. Logistic regression analysis revealed that APR (P < 0.001) and open resection (P = 0.046) were independent predictors of positive CRM status. Moreover, positive CRM was associated with decreased 5-year overall and disease-free survival (P = 0.002 and P = 0.004, respectively). This large single-institution series demonstrated that APR and open resection were independent predictive factors for positive CRM status in rectal cancer. Positive CRM independently decreased the 5-year overall and disease-free survival rates. PMID:26844498

  8. Reliability and limits of agreement of circumferential, water displacement, and optoelectronic volumetry in the measurement of upper limb lymphedema.

    PubMed

    Deltombe, T; Jamart, J; Recloux, S; Legrand, C; Vandenbroeck, N; Theys, S; Hanson, P

    2007-03-01

    We conducted a reliability comparison study to determine the intrarater and inter-rater reliability and the limits of agreement of the volume estimated by circumferential measurements using the frustum sign method and the disk model method, by water displacement volumetry, and by infrared optoelectronic volumetry in the assessment of upper limb lymphedema. Thirty women with lymphedema following axillary lymph node dissection surgery for breast cancer surgery were enrolled. In each patient, the volumes of the upper limbs were estimated by three physical therapists using circumference measurements, water displacement and optoelectronic volumetry. One of the physical therapists performed each measure twice. Intraclass correlation coefficients (ICCs), relative differences, and limits of agreement were determined. Intrarater and interrater reliability ICCs ranged from 0.94 to 1. Intrarater relative differences were 1.9% for the disk model method, 3.2% for the frustum sign model method, 2.9% for water displacement volumetry, and 1.5% for optoelectronic volumetry. Intrarater reliability was always better than interrater, except for the optoelectronic method. Intrarater and interrater limits of agreement were calculated for each technique. The disk model method and optoelectronic volumetry had better reliability than the frustum sign method and water displacement volumetry, which is usually considered to be the gold standard. In terms of low-cost, simplicity, and reliability, we recommend the disk model method as the method of choice in clinical practice. Since intrarater reliability was always better than interrater reliability (except for optoelectronic volumetry), patients should therefore, ideally, always be evaluated by the same therapist. Additionally, the limits of agreement must be taken into account when determining the response of a patient to treatment.

  9. Surgical Removal of Circumferentially Leaked Polymethyl Methacrylate in the Epidural Space of the Thoracic Spine after Percutaneous Vertebroplasty

    PubMed Central

    Kita, Kenichiro; Takata, Yoichiro; Higashino, Kosaku; Yamashita, Kazuta; Tezuka, Fumitake; Sakai, Toshinori; Nagamachi, Akihiro; Sairyo, Koichi

    2017-01-01

    Background  The major complication of percutaneous vertebroplasty (PVP) using polymethyl methacrylate (PMMA) is epidural leakage of PMMA that damages the spinal cord. Methods  This is a case report. Result  A 77-year-old man presented to our institution with a 6-month history of muscle weakness and an intolerable burning sensation of both lower limbs after PVP with PMMA for thoracic compression fracture at T7 at another hospital. His past medical history was significant for hypertension. He had no history of smoking and alcohol. Computed tomography revealed massive leakage of PMMA into the T6 and T7 spinal canal circumferentially surrounding the spinal cord that caused marked encroachment of the thecal sac. Magnetic resonance images revealed cord compression and intramedullary signal change from T6 to T7 level. After we verified that the leaked PMMA could be easily detached from the dura mater in the cadaveric lumbar spine, surgical decompression and removal of epidural PMMA was performed. The leaked PMMA was carefully thinned down with a high-speed diamond burr. Eight pieces of PMMA were detached from the dura mater easily without causing a dural tear. No neurologic deterioration was observed in the postoperative period. The burning sensation resolved, but the muscle weakness remained unchanged. One and a half years postoperatively, the muscle weakness has improved to ⅘ on the manual muscle strength test, but he could not walk without an aid because of spasticity. Conclusion  This report demonstrates the catastrophic epidural extrusion of PMMA following PVP. Extravasated PMMA can be removed through a working space created by means of laminectomy and subtraction of the affected pedicle. Spine surgeons should recognize the possible neurologic complications of PVP and be prepared to treat them using suitable approaches. PMID:28825011

  10. Lateral Extracavitary Approach Versus Posterior Extensive Circumferential Decompression in the Treatment of Complicated Thoracic and Lumbar Tuberculous Spondylitis.

    PubMed

    Omran, Khaled; Abdel-Fattah, Ahmed S; Othman, Ahmed M A; Youssef, Ahmed O; Solimen, Amr; ElRefai, Mohamed A; Saleh, Ahmed N; Ali, Mohammed

    2016-12-21

    The aim of this study was to retrospectively evaluate 45 patients operated upon either by posterior extensive circumferential decompression (PECD) or by the lateral extracavitary (LEC) technique and compare the clinical, radiologic, laboratory, and functional outcomes. The debate continues on the best decompression-fusion technique for treating complicated spinal tuberculosis. In recent times, the advantages of combined surgery have been successfully achieved using the 1-stage salvage technique, with enough accessibility to all 3 spinal columns. From January 2011 to December 2013, 51 patients with complicated spinal tuberculous were surgically treated at our department. After gaining the approval of the local ethics committee, 45 patients and their records were available for evaluation. The patients were divided into 2 groups. Group I included 23 patients treated with PECD and group II included 22 patients treated with LEC. Two authors and an independent observer performed the final clinical assessment by means of clinical examination and by using the Visual Analog Scale and Oswestery Disability Index for determining pain, disability, and quality of life. The radiographs were reviewed independently by 3 authors and a radiologist for fusion, kyphotic angle, and angle loss rate. Neurological assessment using the American Spinal Injury Association motor index was performed by 2 authors and a neurologist independently. The mean follow-up period was 36±5.5 months. In all patients, local symptoms were relieved significantly postoperatively. There were no major complications in this series. Three patients contracted superficial wound infection and 2 developed intercostal neuralgia. Both complications resolved uneventfully and did not influence the outcome. Solid interbody fusion was diagnosed in 43 cases (95.6%). Deformity correction and neurological recovery were significantly improved in both groups (P<0.001). PECD showed better results than LEC. Both procedures

  11. 46 CFR 172.180 - Extent of damage.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    .... Vertical extent From the baseline upward without limit. Grounding Penetration at the Forward End But...) whichever is shorter. Vertical extent from the molded line of the shell at the centerline B/15 or 6.6 feet... is shorter. Vertical extent from the molded line of the shell at the centerline B/15 or 6.6 feet (2m...

  12. Characteristics of the delayed rectifier current (IKr and IKs) in canine ventricular epicardial, midmyocardial, and endocardial myocytes. A weaker IKs contributes to the longer action potential of the M cell.

    PubMed

    Liu, D W; Antzelevitch, C

    1995-03-01

    Recent studies have described regional differences in the electrophysiology and pharmacology of ventricular myocardium in canine, feline, rat, guinea pig, and human hearts. In this study, we use standard microelectrode and whole-cell patch-clamp techniques to examine the characteristics of the action potential and the delayed rectifier K+ current (IK) in epicardial, M region (deep subepicardial to midmyocardial), and endocardial cells isolated from the canine left ventricle. Cells from the M region displayed much longer action potential durations (APDs) at slow rates. At a basic cycle length of 4 s, APD measured at 90% repolarization was 358 +/- 16 (mean +/- SEM), 262 +/- 12, and 287 +/- 11 ms in cells from the M region, epicardium, and endocardium, respectively. Steady state APD-rate relations were steeper in cells from the M region. In complete Tyrode's solution, IK was smaller in myocytes from the M region when compared with those isolated from the epicardium or endocardium. Further characterization of IK was conducted in a Na(+)-, K(+)-, and Ca(2+)-free bath solution to isolate the slowly activating component of the delayed rectifier (IKs) from the rapidly activating component (IKr). IKs was significantly smaller in M cells than in epicardial and endocardial cells. With repolarization to -20 mV, IKs tail current density was 1.99 +/- 0.30 pA/pF (mean +/- SEM) in epicardial cells, 1.83 +/- 0.18 pA/pF in endocardial cells, and 0.92 +/- 0.14 pA/pF in M cells. Voltage dependence and time course of activation and deactivation of IKs were similar in the three cell types. The relative contribution of IKr and IKs among the three cell types was examined by using 6 mmol/L [K+]o Tyrode's solution with and without E-4031, a highly selective blocker of IKr. An E-4031-sensitive current was observed in the presence but not in the absence of extracellular K+. This rapidly activating component showed characteristics similar to those of IKr as described in rabbit and cat

  13. The Combined Incremental Prognostic Value of LVEF, Late Gadolinium Enhancement, and Global Circumferential Strain Assessed by CMR.

    PubMed

    Mordi, Ify; Bezerra, Hiram; Carrick, David; Tzemos, Nikolaos

    2015-05-01

    This study aimed to assess the incremental prognostic value of global circumferential strain (GCS), as measured using cardiac magnetic resonance (CMR) tagging, in addition to baseline clinical characteristics, left ventricular ejection fraction (LVEF), and late gadolinium enhancement (LGE), in the prediction of major adverse cardiovascular events (MACE) in an unselected cohort of patients. LVEF is a powerful predictor of mortality and is used for guiding treatment decisions. It is, however, subject to limitations. The value of GCS measured by CMR tagging in patients with suspected cardiac disease has not been fully explored despite its being considered as the gold standard noninvasive method of assessment of LV deformation. We prospectively evaluated data from 539 consecutive patients referred for CMR who underwent a CMR protocol that included cine imaging, tagging, and LGE. The primary endpoint was the prevalence of MACE, defined as a composite of all-cause mortality, heart failure-related hospitalization, and aborted sudden cardiac death. MACE occurred in 62 of 539 patients (11.5%) over a mean follow-up period of 2.2 years. History of ischemic heart disease (IHD) and beta-blocker use were both significant clinical predictors of adverse outcomes. All 3 CMR parameters were significant multivariate predictors of the primary outcome when added to significant clinical predictors (LVEF, hazard ratio [HR]: 0.96 [95% confidence interval [CI]: 0.94 to 0.99; p = 0.005]; presence of LGE, HR: 2.07 [95% CI: 1.03 to 4.14; p = 0.04]; GCS, HR: 1.11 [95% CI: 1.02 to 1.21; p = 0.041]). Global chi-square increased significantly with the addition of both LGE and GCS. Both the presence of LGE and reduced GCS had independent prognostic value in the overall cohort. Patients with LVEF ≥35% but LGE present and reduced GCS had a poor outcome similar to that in those with LVEF <35%. We found, in a large-scale cohort of patients, that GCS, in addition to clinical variables, LVEF, and LGE

  14. Efficacy and safety of novel epicardial circumferential left atrial ablation with pulmonary vein isolation in sustained atrial fibrillation.

    PubMed

    Jiang, Zhaolei; Yin, Hang; He, Yi; Ma, Nan; Tang, Min; Liu, Hao; Ding, Fangbao; Mei, Ju

    2015-09-01

    The aim of this study was to examine the efficacy and safety of this novel epicardial circumferential left atrial ablation (CLAA) with pulmonary vein isolation (PVI) in sustained atrial fibrillation (AF). Thirty domestic pigs were divided equally into 3 groups: AF without ablation (AF group), AF with PVI (PVI group), and AF with CLAA and PVI (CLAA + PVI group). AF was induced by rapid atrial pacing. After AF was induced, CLAA and PVI were performed for pigs in CLAA + PVI group, and PVI was performed for pigs in PVI group. AF vulnerability, AF duration, and histology were performed in all groups. All pigs developed sustained AF after 6.27 ± 0.69 weeks of rapid atrial pacing. All pigs successfully underwent isolated PVI or CLAA with PVI on the beating heart in PVI group or CLAA + PVI group. Isolated PVI terminated AF in 3 of 20 pigs (15 %), and CLAA with PVI terminated AF in 5 of 8 pigs (62.5 %, P = 0.022). Compared with AF group (10/10), the incidence of sustained AF by burst pacing was significantly decreased in PVI group (3/10, P = 0.003) or CLAA + PVI group (0/10, P < 0.001). There was no significant difference between PVI group and CLAA + PVI group (P = 0.211). AF duration was significantly decreased in CLAA + PVI group (734.70 ± 177.81 s, 95 % CI 607.51-861.89) compared with PVI group (1217.90 ± 444.10 s, 95 % CI 900.21-1535.59, P = 0.008). Also, AF duration was significantly decreased in PVI group (P = 0.003) or CLAA + PVI group (P < 0.001) in comparison with AF duration in AF group (average 1800 s). Epicardial CLAA could ablate the left atrial roof and posterior wall together safely and reliably. Compared with PVI alone, CLAA with PVI may be able to improve the rate of acute termination of persistent AF. It may be useful in selecting the best ablation approaches for patients with persistent AF.

  15. Severe Left Atrioventricular Valve Regurgitation Due to Discontinuity between the Leaflets of the Aortic and Left Atrioventricular Valves in a Patient with Endocardial Cushion Defect: A Rare Case Report.

    PubMed

    Nabati, Maryam; Habibi, Valiolla; Soleimani, Aria; Shokri, Mojtaba

    2015-06-01

    Discontinuities between the leaflets of the aortic and left atrioventricular valves are uncommon congenital malformations. The anomaly may be discovered during surgery without preoperative diagnosis. It represents a spectrum of anomalies that result from interruption of the normal development of the endocardial cushions during the fetal life. We describe a rare case of Down syndrome with transient complete atrioventricular block and discontinuity between the leaflets of the aortic and left atrioventricular valves without intervening fibrous band, leading to separation and detachment between them. It caused severe eccentric jet of regurgitation originated from left ventricular outflow tract and base of anterior leaflet of left atrioventricular valve into the left atrium. He underwent cardiopulmonary bypass, and the defect between left atrioventricular valve and aortic annuli was sewn. Permanent epicardial pacing was inserted during cardiac surgery. To the best of our knowledge, such a case has not been previously reported in the literature. © 2014, Wiley Periodicals, Inc.

  16. 46 CFR 42.20-11 - Extent of damage.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Extent of damage. 42.20-11 Section 42.20-11 Shipping... Freeboards § 42.20-11 Extent of damage. When doing the calculations required by §§ 42.20-6(a), 42.20-7(a) and 42.20-8(a), the following must be assumed: (a) The vertical extent of damage in all cases must be...

  17. 48 CFR 828.7102 - Extent of indemnification.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... GENERAL CONTRACTING REQUIREMENTS BONDS AND INSURANCE Indemnification of Contractors, Medical Research or Development Contracts 828.7102 Extent of indemnification. (a) A contract for medical research or...

  18. 48 CFR 828.7102 - Extent of indemnification.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... GENERAL CONTRACTING REQUIREMENTS BONDS AND INSURANCE Indemnification of Contractors, Medical Research or Development Contracts 828.7102 Extent of indemnification. (a) A contract for medical research or...

  19. 48 CFR 828.7102 - Extent of indemnification.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... GENERAL CONTRACTING REQUIREMENTS BONDS AND INSURANCE Indemnification of Contractors, Medical Research or Development Contracts 828.7102 Extent of indemnification. (a) A contract for medical research or...

  20. 48 CFR 828.7102 - Extent of indemnification.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... GENERAL CONTRACTING REQUIREMENTS BONDS AND INSURANCE Indemnification of Contractors, Medical Research or Development Contracts 828.7102 Extent of indemnification. (a) A contract for medical research or...

  1. 48 CFR 828.7102 - Extent of indemnification.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... GENERAL CONTRACTING REQUIREMENTS BONDS AND INSURANCE Indemnification of Contractors, Medical Research or Development Contracts 828.7102 Extent of indemnification. (a) A contract for medical research or...

  2. Automated assessments of circumferential strain from cine CMR correlate with LVEF declines in cancer patients early after receipt of cardio-toxic chemotherapy.

    PubMed

    Jolly, Marie-Pierre; Jordan, Jennifer H; Meléndez, Giselle C; McNeal, Gary R; D'Agostino, Ralph B; Hundley, W Gregory

    2017-08-02

    In patients with cancer receiving potentially cardio-toxic chemotherapy, measurements of left ventricular (LV) circumferential or longitudinal strain are often used clinically to identify myocardial dysfunction. Using a new software algorithm, we sought to determine in individuals receiving treatment for cancer the association between automated assessments of LV mean mid-wall circumferential strain and conventional measures of LV ejection fraction (EF) both obtained from cardiovascular magnetic resonance (CMR) cine balanced steady-state free-precession (bSSFP) white-blood acquisitions. Before and 3 months after initiating treatment with potentially cardio-toxic chemotherapy, 72 individuals (aged 54 ± 14 years with breast cancer [39%], lymphoma [49%], or sarcoma [12%]) underwent serial CMR cine bSSFP assessments of LV volumes and EF, and mean mid-wall circumferential strain determined from these same cine images as well as from additional tagged CMR images. On the cine images, assessments of strain were obtained using the newly developed deformation-based segmentation algorithm. Assessments of LV volumes/EF from the cine images and strain from tagged CMR were accomplished using commercially available software. All measures were analyzed in a blinded fashion independent of one another. Acceptable measures for the automated assessments of mean mid-wall circumferential strain from the cine images were obtained in 142 of 144 visits (98.6%) with an overall analysis time averaging 6:47 ± 1:06 min. The results from these automated measures averaged -18.8 ± 2.9 at baseline and -17.6 ± 3.1 at 3 months (p = 0.001). Left ventricular EF declined slightly from 65 ± 7% at baseline to 62 ± 7% at 3 months (p = 0.0002). The correlation between strain from cine imaging and LVEF was r = -0.61 (p < 0.0001). In addition, the 3-month changes in LV strain and LVEF were correlated (r = -0.49; p < 0.0001). The correlation between cine and tagged derived

  3. Results of Single-Staged Posterior Decompression and Circumferential Fusion Using a Transpedicular Approach to Correct a Kyphotic Deformity due to Thoracolumbar Spinal Tuberculosis

    PubMed Central

    Modi, Jayprakash; Soman, Shardul; Patel, Harshil; Dhanani, Shrikant

    2016-01-01

    Study Design This is a prospective study. Purpose The aim of this study was to investigate the results of single-staged posterior decompression and circumferential fusion using a transpedicular approach to correct a kyphotic deformity due to thoracolumbar spinal tuberculosis. Overview of Literature Surgical management is frequently an imperative choice to achieve spinal decompression and deformity correction due to tuberculosis to relieve pain, improve neurology, and reconstruct the spine stability. Since the time anterior radical debridement and noninstrumented fusion was described, it has become apparent that even anterior debridement and bone grafting was often unsatisfactory in correcting or preventing the progression of kyphosis deformity. With the advent of modern segmental spinal instrumentation systems, isolated posterior instrumentation; combined anterior and posterior fusion; and single-staged posterior decompression and circumferential fusion have been described by many authors for correcting angular deformity and stabilizing the spine; however, there is a lack of consensus regarding the most effective means of correcting the deformity due to thoracolumbar spinal tuberculosis. Methods This is a prospective study of 20 patients with thoracolumbar spinal tuberculosis who underwent surgery at our institute. Results Twenty patients who were started on antituberculosis treatment underwent surgery using a single-staged posterior approach involving fixation, decompression, and kyphosis correction. Preoperatively, all patients had varying degrees of neurological deficit and a 27.45° average kyphotic angle, which improved. At the 1-year follow-up, correction was maintained at 6.9°, and 55% of patients showed neurological improvement. None of the patients experienced neurological deterioration. Two patients with lumbar spine tuberculosis underwent revision surgery because of nonunion. Conclusions The procedure of posterior decompression, fixation, and

  4. The combination of extracorporeal shock wave therapy and noncontact apoptosis-inducing radiofrequency achieved significant waist circumferential reduction: a pilot study.

    PubMed

    Kim, Hyeyeon

    2017-06-30

    A paradigm shift towards noninvasive body contouring has occurred over the past few years. Radiofrequency (RF) is one popular treatment method. Noncontact-type RF systems with frequencies in the tens of megahertz represent a novel approach. The current pilot study investigated the efficacy of an interesting combination of extracorporeal shock wave therapy (ESWT) and an apoptosis-inducing RF (AiRF) system for circumferential reduction. Twenty-seven females, ages ranging from 13-69 years, (mean age 37.96 years) participated in the study. They were assigned to two treatment-based groups: Group A (n=19) and Group B (n=8). A voluntary daily dietary restriction plan of 500 kcal was put in place for all subjects. A combination of two different devices was used; an extracorporeal shock wave therapy (ESWT) system and a 27.12 MHz AiRF system. Either 4 (n=28) or 6 sessions (n=19) were given, one week apart. In Group A, the ESWT was applied before the RF with the reverse order of application in Group B. Weight and waist circumference were noted at baseline, then one week after the 4(th) and the 6(th) treatment sessions at which points clinical photography was also obtained. All patients showed statistically significant waist circumferential loss in both the 4- and 6-week treated groups: Group A, 6.3 cm and 8.8 cm; Group B, 5.9 cm and 6.4 cm, respectively. Greater circumference loss tended to be seen in Group A in both groups, but without statistical significance. No patient complained of pain during or after the treatment sessions, and there were no adverse events. This pilot study showed that the combination of ESWT and AiRF was safe and effective for significant waist circumferential reduction. The results tended to be better when ESWT was applied before AiRF, although the difference was not significant.

  5. Semi-Circumferential Decompression: Microsurgical Total en-bloc Ligamentum Flavectomy to Treat Lumbar Spinal Stenosis with Grade I Degenerative Spondylolisthesis

    PubMed Central

    Choi, Jun Cheol; Oh, Sang Hun; Park, Sub Ri; Park, Sang Jun; Cho, Nam Ik

    2015-01-01

    Background To describe and assess clinical outcomes of the semi-circumferential decompression technique for microsurgical en-bloc total ligamentum flavectomy with preservation of the facet joint to treat the patients who have a lumbar spinal stenosis with degenerative spondylolisthesis. Methods We retrospectively analyzed the clinical and radiologic outcomes of 19 patients who have a spinal stenosis with Meyerding grade I degenerative spondylolisthesis. They were treated using the "semi-circumferential decompression" method. We evaluated improvements in back and radiating pain using a visual analogue scale (VAS) and the Oswestry Disability Index (ODI). We also evaluated occurrence of spinal instability on radiological exam using percentage slip and slip angle. Results The mean VAS score for back pain decreased significantly from 6.3 to 4.3, although some patients had residual back pain. The mean VAS for radiating pain decreased significantly from 8.3 to 2.5. The ODI score improved significantly from 25.3 preoperatively to 10.8 postoperatively. No significant change in percentage slip was observed (10% preoperatively vs. 12.2% at the last follow-up). The dynamic percentage slip (gap in percentage slip between flexion and extension X-ray exams) did not change significantly (5.2% vs. 5.8%). Slip angle and dynamic slip angle did not change (3.2° and 8.2° vs. 3.6° and 9.2°, respectively). Conclusions The results suggested that semi-circumferential decompression is a clinically recommendable procedure that can improve pain. This procedure does not cause spinal instability when treating patients who have a spinal stenosis with degenerative spondylolisthesis. PMID:26640630

  6. 2D versus 3D cross-correlation-based radial and circumferential strain estimation using multiplane 2D ultrafast ultrasound in a 3D atherosclerotic carotid artery model.

    PubMed

    Fekkes, Stein; Swillens, Abigail E S; Hansen, Hendrik H G; Saris, Anne E C M; Nillesen, Maartje M; Iannaccone, Francesco; Segers, Patrick; de Korte, Chris L

    2016-08-25

    Three-dimensional strain estimation might improve the detection and localization of high strain regions in the carotid artery for identification of vulnerable plaques. This study compares 2D vs. 3D displacement estimation in terms of radial and circumferential strain using simulated ultrasound images of a patient specific 3D atherosclerotic carotid artery model at the bifurcation embedded in surrounding tissue generated with ABAQUS software. Global longitudinal motion was superimposed to the model based on literature data. A Philips L11-3 linear array transducer was simulated which transmitted plane waves at 3 alternating angles at a pulse repetition rate of 10 kHz. Inter-frame radiofrequency ultrasound data were simulated in Field II for 191 equally spaced longitudinal positions of the internal carotid artery. Accumulated radial and circumferential displacements were estimated using tracking of the inter-frame displacements estimated by a two-step normalized cross-correlation method and displacement compounding. Least squares strain estimation was performed to determine accumulated radial and circumferential strain. The performance of the 2D and 3D method was compared by calculating the root-mean-squared error of the estimated strains with respect to the reference strains obtained from the model. More accurate strain images were obtained using the 3D displacement estimation for the entire cardiac cycle. The 3D technique clearly outperformed the 2D technique in phases with high inter-frame longitudinal motion. In fact the large inter-frame longitudinal motion rendered it impossible to accurately track the tissue and cumulate strains over the entire cardiac cycle with the 2D technique.

  7. 2-D Versus 3-D Cross-Correlation-Based Radial and Circumferential Strain Estimation Using Multiplane 2-D Ultrafast Ultrasound in a 3-D Atherosclerotic Carotid Artery Model.

    PubMed

    Fekkes, Stein; Swillens, Abigail E S; Hansen, Hendrik H G; Saris, Anne E C M; Nillesen, Maartje M; Iannaccone, Francesco; Segers, Patrick; de Korte, Chris L

    2016-10-01

    Three-dimensional (3-D) strain estimation might improve the detection and localization of high strain regions in the carotid artery (CA) for identification of vulnerable plaques. This paper compares 2-D versus 3-D displacement estimation in terms of radial and circumferential strain using simulated ultrasound (US) images of a patient-specific 3-D atherosclerotic CA model at the bifurcation embedded in surrounding tissue generated with ABAQUS software. Global longitudinal motion was superimposed to the model based on the literature data. A Philips L11-3 linear array transducer was simulated, which transmitted plane waves at three alternating angles at a pulse repetition rate of 10 kHz. Interframe (IF) radio-frequency US data were simulated in Field II for 191 equally spaced longitudinal positions of the internal CA. Accumulated radial and circumferential displacements were estimated using tracking of the IF displacements estimated by a two-step normalized cross-correlation method and displacement compounding. Least-squares strain estimation was performed to determine accumulated radial and circumferential strain. The performance of the 2-D and 3-D methods was compared by calculating the root-mean-squared error of the estimated strains with respect to the reference strains obtained from the model. More accurate strain images were obtained using the 3-D displacement estimation for the entire cardiac cycle. The 3-D technique clearly outperformed the 2-D technique in phases with high IF longitudinal motion. In fact, the large IF longitudinal motion rendered it impossible to accurately track the tissue and cumulate strains over the entire cardiac cycle with the 2-D technique.

  8. Dimensions and circumferential stress-strain relation in the porcine esophagus in vitro determined by combined impedance planimetry and high-frequency ultrasound.

    PubMed

    Zhao, Jingbo; Jørgensen, Claus S; Liao, Donghua; Gregersen, Hans

    2007-05-01

    The mechanical properties of the esophagus are important for its function because the esophagus is subjected to changes in wall stress and strains caused by the passage of boli and the action of peristalsis. Electrodes for impedance planimetry and an ultrasound transducer were placed on the probe inside a fluid-filled bag and used to study the circumferential stress and strain relation of the porcine esophagus in vitro. Impedance planimetry was used to determine the luminal cross-sectional area (CSA) and high-frequency ultrasound was used to determine the esophageal wall thickness during bag distension. Circumferential stress and strain were computed from steady-state values of pressure, CSA, and wall thickness. The incremental elastic modulus was obtained from the slope of the stress-strain curve and was plotted as a function of strain. The steady state pressure-CSA relation was nonlinear. At the lowest and highest luminal pressure load of 1 and 5 kPa, the steady state CSA was 159+/-20 and 338+/-25 mm(2), respectively. In the same pressure range, the wall thickness decreased from 1.93+/-0.08 to 1.44+/-0.08 mm. The slope of the stress-strain curve was 2.58+/-0.35 kPa. The circumferential stress and the incremental elastic modulus as function of the strain were exponential, that is, the tissue was soft at physiologic pressures and stiffer in the supraphysiologic pressure range. These biomechanical properties of the esophageal wall seem to prevent overstretch of the esophageal wall when luminal loading becomes supraphysiologic.

  9. A new multichannel time reversal focusing method for circumferential Lamb waves and its applications for defect detection in thick-walled pipe with large-diameter.

    PubMed

    Liu, Zenghua; Xu, Qinglong; Gong, Yu; He, Cunfu; Wu, Bin

    2014-09-01

    This paper proposes a new multichannel time reversal focusing (MTRF) method for circumferential Lamb waves which is based on modified time reversal algorithm and applies this method for detecting different kinds of defects in thick-walled pipe with large-diameter. The principle of time reversal of circumferential Lamb waves in pipe is presented along with the influence from multiple guided wave modes and propagation paths. Experimental study is carried out in a thick-walled and large-diameter pipe with three artificial defects, namely two axial notches on its inner and outer surface respectively, and a corrosion-like defect on its outer surface. By using the proposed MTRF method, the multichannel signals focus at the defects, leading to the amplitude improvement of the defect scattered signal. Besides, another energy focus arises in the direct signal due to the partial compensation of dispersion and multimode of circumferential Lamb waves, alongside the multichannel focusing, during MTRF process. By taking the direct focus as a time base, accurate defect localization is implemented. Secondly, a new phenomenon is exhibited in this paper that defect scattered wave packet appears just before the right boundary of truncation window after time reversal, and to which two feasible explanations are given. Moreover, this phenomenon can be used as the theoretical basis in the determination of defect scattered waves in time reversal response signal. At last, in order to detect defects without prior knowing their exact position, a large-range truncation window is used in the proposed method. As a result, the experimental operation of MTRF method is simplified and defect detection and localization are well accomplished. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. [Rectal cancer within 10 cm. Comparison of the radicality of laparoscopic and open surgical techniques with regard to the circumferential resection margin and the completeness of mesorectal excision].

    PubMed

    Dušek, T; Ferko, A; Orhalmi, J; Chobola, M; Nikolov, D H; Hovorková, E; Cermáková, E

    2013-06-01

    The issue of achieving radical circumferential margin in laparoscopic rectal surgery has not yet been satisfactorily clarified. In this paper we have focused on circumferential margin assessment and the quality of the mesorectal excision, comparing laparoscopic and open resection for cancer of the middle and lower rectum. The results of surgical procedures for middle and low rectal cancer were analysed. All the interventions were performed at the Department of Surgery, Teaching Hospital in Hradec Kralove, during the period from January 2011 to December 2012. The data were prospectively collected and entered in the Rectal Cancer Registry. Age, gender, BMI, tumour localisation and topography, the clinical stage, preoperative chemoradiotherapy and response to it, the type of surgery, distal and circumferential margin characteristics, mesorectal excision quality, pT and pN were compared for laparoscopic and open surgery. A total of 161 patients were operated on for rectal cancer during the abovementioned period. 94 patients were included in the trial following selection. Laparoscopy was used in 40 patients and open surgery in 54 patients. Laparoscopic approach was performed in 33 (82.5%) low anterior resections (including four intersphincteric resections), 6 (15%) abdominoperineal amputations and 1 (2.5%) Hartmanns procedure. Open surgery was used for 26 (48.1%) low anterior resections, 21 (38.9%) APR and 7 (13%) Hartmanns procedures. Complete mesorectal excision was achieved in 45% of the laparoscopic resections vs. 46.3% of open resections. Nearly complete excision was performed in 22.5% and 11.1%, respectively. Finally, incomplete excision was described in 30% vs. 38.9%. No available data for TME was detected in three patients. The differences in TME were not statistically significant. Positive circumferential margin was found in 5 (12.5%) patients in the laparoscopy group; on the contrary, in the group undergoing open surgery, pCRO+ was found in 15 (27.8%) patients

  11. 26 CFR 2.1-24 - Extent of tax liability.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 26 Internal Revenue 14 2014-04-01 2013-04-01 true Extent of tax liability. 2.1-24 Section 2.1-24 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) INCOME TAX (CONTINUED) MARITIME CONSTRUCTION RESERVE FUND § 2.1-24 Extent of tax liability. (a) Declared value excess-profits...

  12. 46 CFR 287.24 - Extent of tax liability.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 8 2011-10-01 2011-10-01 false Extent of tax liability. 287.24 Section 287.24 Shipping... OPERATORS ESTABLISHMENT OF CONSTRUCTION RESERVE FUNDS § 287.24 Extent of tax liability. (a) Declared value excess-profits tax. Gain which is includible in gross income under § 287.23 shall be included in gross...

  13. 14 CFR 252.8 - Extent of smoking restrictions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false Extent of smoking restrictions. 252.8... PROCEEDINGS) ECONOMIC REGULATIONS SMOKING ABOARD AIRCRAFT § 252.8 Extent of smoking restrictions. The restrictions on smoking described in §§ 252.3 through 252.7 shall apply to all locations within the aircraft....

  14. 14 CFR 252.8 - Extent of smoking restrictions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false Extent of smoking restrictions. 252.8... PROCEEDINGS) ECONOMIC REGULATIONS SMOKING ABOARD AIRCRAFT § 252.8 Extent of smoking restrictions. The restrictions on smoking described in §§ 252.3 through 252.7 shall apply to all locations within the aircraft....

  15. 14 CFR 252.8 - Extent of smoking restrictions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false Extent of smoking restrictions. 252.8... PROCEEDINGS) ECONOMIC REGULATIONS SMOKING ABOARD AIRCRAFT § 252.8 Extent of smoking restrictions. The restrictions on smoking described in §§ 252.3 through 252.7 shall apply to all locations within the aircraft....

  16. 14 CFR 252.8 - Extent of smoking restrictions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Extent of smoking restrictions. 252.8... PROCEEDINGS) ECONOMIC REGULATIONS SMOKING ABOARD AIRCRAFT § 252.8 Extent of smoking restrictions. The restrictions on smoking described in §§ 252.3 through 252.7 shall apply to all locations within the aircraft....

  17. 14 CFR 252.8 - Extent of smoking restrictions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Extent of smoking restrictions. 252.8... PROCEEDINGS) ECONOMIC REGULATIONS SMOKING ABOARD AIRCRAFT § 252.8 Extent of smoking restrictions. The restrictions on smoking described in §§ 252.3 through 252.7 shall apply to all locations within the aircraft....

  18. 32 CFR 536.56 - Negotiations-purpose and extent.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 3 2011-07-01 2009-07-01 true Negotiations-purpose and extent. 536.56 Section... CLAIMS AGAINST THE UNITED STATES Investigation and Processing of Claims § 536.56 Negotiations—purpose and extent. It is DA policy to settle meritorious claims promptly and fairly through direct negotiation at...

  19. 32 CFR 536.56 - Negotiations-purpose and extent.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 3 2013-07-01 2013-07-01 false Negotiations-purpose and extent. 536.56 Section... CLAIMS AGAINST THE UNITED STATES Investigation and Processing of Claims § 536.56 Negotiations—purpose and extent. It is DA policy to settle meritorious claims promptly and fairly through direct negotiation at...

  20. 32 CFR 536.56 - Negotiations-purpose and extent.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 3 2010-07-01 2010-07-01 true Negotiations-purpose and extent. 536.56 Section... CLAIMS AGAINST THE UNITED STATES Investigation and Processing of Claims § 536.56 Negotiations—purpose and extent. It is DA policy to settle meritorious claims promptly and fairly through direct negotiation at...

  1. Cyberbullying in Schools: Nature and Extent of Canadian Adolescents' Experience

    ERIC Educational Resources Information Center

    Li, Qing

    2005-01-01

    This study is an exploration of the cyberbullying issue. The primary focus is on the examination of the nature and extent of adolescents' cyberbullying experiences. Particularly, the following research questions guide this exploration: (1) To what extent do adolescents experience cyberbullying? (2) What are the characteristics of cyberbullying?…

  2. 5 CFR 1.4 - Extent of the excepted service.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Extent of the excepted service. 1.4 Section 1.4 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE RULES COVERAGE AND DEFINITIONS (RULE I) § 1.4 Extent of the excepted service. (a) The excepted service shall include all civilian...

  3. 10 CFR 52.25 - Extent of activities permitted.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 2 2010-01-01 2010-01-01 false Extent of activities permitted. 52.25 Section 52.25 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) LICENSES, CERTIFICATIONS, AND APPROVALS FOR NUCLEAR POWER PLANTS Early Site Permits § 52.25 Extent of activities permitted. If the activities authorized by § 52.24(c...

  4. 5 CFR 1.2 - Extent of the competitive service.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Extent of the competitive service. 1.2 Section 1.2 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE RULES COVERAGE AND DEFINITIONS (RULE I) § 1.2 Extent of the competitive service. The competitive service shall include: (a) All...

  5. It Is All Relative: How Young Children Encode Extent

    ERIC Educational Resources Information Center

    Duffy, Sean; Huttenlocher, Janellen; Levine, Susan

    2005-01-01

    Two experiments tested the ability of 4- and 8-year-old children to encode the extent of a target dowel and later discriminate between the target and a foil having a novel extent. By manipulating the heights of containers in which we presented the stimuli we tested whether children used the relation between the dowels and containers for encoding…

  6. 5 CFR 1.4 - Extent of the excepted service.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 5 Administrative Personnel 1 2014-01-01 2014-01-01 false Extent of the excepted service. 1.4 Section 1.4 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT CIVIL SERVICE RULES COVERAGE AND DEFINITIONS (RULE I) § 1.4 Extent of the excepted service. (a) The excepted service shall include all civilian...

  7. 38 CFR 21.3303 - Extent of training.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... determines that the eligible person's physical or mental condition permits training for that amount of time... 38 Pensions, Bonuses, and Veterans' Relief 2 2010-07-01 2010-07-01 false Extent of training. 21.... Chapter 35 Special Restorative Training § 21.3303 Extent of training. (a) Length of special...

  8. 10 CFR 52.25 - Extent of activities permitted.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 2 2014-01-01 2014-01-01 false Extent of activities permitted. 52.25 Section 52.25 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) LICENSES, CERTIFICATIONS, AND APPROVALS FOR NUCLEAR POWER PLANTS Early Site Permits § 52.25 Extent of activities permitted. If the activities authorized by § 52.24(c...

  9. 10 CFR 52.25 - Extent of activities permitted.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 2 2012-01-01 2012-01-01 false Extent of activities permitted. 52.25 Section 52.25 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) LICENSES, CERTIFICATIONS, AND APPROVALS FOR NUCLEAR POWER PLANTS Early Site Permits § 52.25 Extent of activities permitted. If the activities authorized by § 52.24(c...

  10. 10 CFR 52.25 - Extent of activities permitted.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 2 2011-01-01 2011-01-01 false Extent of activities permitted. 52.25 Section 52.25 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) LICENSES, CERTIFICATIONS, AND APPROVALS FOR NUCLEAR POWER PLANTS Early Site Permits § 52.25 Extent of activities permitted. If the activities authorized by § 52.24(c...

  11. Practical constraints on estimation of source extent with MEG beamformers.

    PubMed

    Hillebrand, Arjan; Barnes, Gareth R

    2011-02-14

    We aimed to determine practical constraints on the estimation of the spatial extent of neuronal activation using MEG beamformers. Correct estimation of spatial extent is a pre-requisite for accurate models of electrical activity, allows one to estimate current density, and enables non-invasive monitoring of functional recovery following stroke. The output of an MEG beamformer is maximum when the correct source model is used, so that the spatial extent of a source can in principal be determined through evaluation of different source models with the beamformer. Here, we simulated 275-channel MEG data using sources of varying spatial extents that followed the cortical geometry. These data were subsequently used to estimate the spatial extent of generic disc elements without knowledge of the underlying surface, and we compared these results to estimates based on cortical surface geometry (with and without error in surface location). We found that disc-shaped source models are too simplistic, particularly for areas with high curvature. For areas with low curvature spatial extent was underestimated, although on average there was a linear relationship between the true and estimated extent. In contrast, cortical surface models gave accurate predictions of spatial extent. However, adding small errors (>2 mm) to the estimated location of the cortical surface abolished this relationship between true and estimated extent, implying that accurate co-registration is needed with such models. Our results show that models exploiting surface information are necessary in order to model spatial extent and in turn current density, but in order to render such models applicable in practical situations, the accuracy of the cortical surface model itself needs to improve.