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Sample records for aortic ring constriction

  1. Mechanism of Cytokinetic Contractile Ring Constriction in Fission Yeast

    PubMed Central

    Stachowiak, Matthew R.; Laplante, Caroline; Chin, Harvey F.; Guirao, Boris; Karatekin, Erdem; Pollard, Thomas D.; O’Shaughnessy, Ben

    2014-01-01

    SUMMARY Cytokinesis involves constriction of a contractile actomyosin ring. The mechanisms generating ring tension and setting the constriction rate remain unknown, since the organization of the ring is poorly characterized, its tension was rarely measured, and constriction is coupled to other processes. To isolate ring mechanisms we studied fission yeast protoplasts, where constriction occurs without the cell wall. Exploiting the absence of cell wall and actin cortex, we measured ring tension and imaged ring organization, which was dynamic and disordered. Computer simulations based on the amounts and biochemical properties of the key proteins showed that they spontaneously self-organize into a tension-generating bundle. Together with rapid component turnover, the self-organization mechanism continuously reassembles and remodels the constricting ring. Ring constriction depended on cell shape, revealing that the ring operates close to conditions of isometric tension. Thus, the fission yeast ring sets its own tension, but other processes set the constriction rate. PMID:24914559

  2. Effect of aortic constriction on the functional border zone

    SciTech Connect

    Gallagher, K.P.; Ning, X.H.; Gerren, R.A.; Drake, D.H.; Dunham, W.R.

    1987-04-01

    To evaluate how aortic constriction affects nonischemic myocardium adjacent to the perfusion boundary (the functional border zone) the authors measured systolic wall thickening (dWT) with sonomicrometers in eight anesthetized, open-chest dogs. The locations of the wall thickening measurements relative to the perfusion boundary (PB) were determined with myocardial blood flow (radioactivity-labelled microspheres) maps constructed from multiple, small tissue samples. In nonischemic myocardium more than 10 mm from the PB produced by circumflex coronary occlusion, dWT increased significantly from 2.57 +/- 0.62 to 3.24 +/- 0.73 mm. Within 10 mm of the PB, however, dWT did not change significantly. When the aorta was mechanically constricted, peak systolic pressure increased approx.50%. Wall thickening decreased to the same relative degree in nonischemic muscle less than 10 mm and more than 10 mm from the perfusion boundary. By fitting sigmoid curves to the data, they estimated the extent of nonischemic dysfunction. It averaged 26 +/- 6/sup 0/ (6-8 mm of endocardial circumference) during coronary occlusion alone and it was not significantly different (29 +/- 11/sup 0/) after aortic constriction. Thus elevated afterload affects nonischemic myocardium uniformly and does not increase the size ore relative severity of the functional border zone.

  3. Still and rotating myosin clusters determine cytokinetic ring constriction.

    PubMed

    Wollrab, Viktoria; Thiagarajan, Raghavan; Wald, Anne; Kruse, Karsten; Riveline, Daniel

    2016-07-01

    The cytokinetic ring is essential for separating daughter cells during division. It consists of actin filaments and myosin motors that are generally assumed to organize as sarcomeres similar to skeletal muscles. However, direct evidence is lacking. Here we show that the internal organization and dynamics of rings are different from sarcomeres and distinct in different cell types. Using micro-cavities to orient rings in single focal planes, we find in mammalian cells a transition from a homogeneous distribution to a periodic pattern of myosin clusters at the onset of constriction. In contrast, in fission yeast, myosin clusters rotate prior to and during constriction. Theoretical analysis indicates that both patterns result from acto-myosin self-organization and reveals differences in the respective stresses. These findings suggest distinct functional roles for rings: contraction in mammalian cells and transport in fission yeast. Thus self-organization under different conditions may be a generic feature for regulating morphogenesis in vivo.

  4. Still and rotating myosin clusters determine cytokinetic ring constriction.

    PubMed

    Wollrab, Viktoria; Thiagarajan, Raghavan; Wald, Anne; Kruse, Karsten; Riveline, Daniel

    2016-01-01

    The cytokinetic ring is essential for separating daughter cells during division. It consists of actin filaments and myosin motors that are generally assumed to organize as sarcomeres similar to skeletal muscles. However, direct evidence is lacking. Here we show that the internal organization and dynamics of rings are different from sarcomeres and distinct in different cell types. Using micro-cavities to orient rings in single focal planes, we find in mammalian cells a transition from a homogeneous distribution to a periodic pattern of myosin clusters at the onset of constriction. In contrast, in fission yeast, myosin clusters rotate prior to and during constriction. Theoretical analysis indicates that both patterns result from acto-myosin self-organization and reveals differences in the respective stresses. These findings suggest distinct functional roles for rings: contraction in mammalian cells and transport in fission yeast. Thus self-organization under different conditions may be a generic feature for regulating morphogenesis in vivo. PMID:27363521

  5. Still and rotating myosin clusters determine cytokinetic ring constriction

    PubMed Central

    Wollrab, Viktoria; Thiagarajan, Raghavan; Wald, Anne; Kruse, Karsten; Riveline, Daniel

    2016-01-01

    The cytokinetic ring is essential for separating daughter cells during division. It consists of actin filaments and myosin motors that are generally assumed to organize as sarcomeres similar to skeletal muscles. However, direct evidence is lacking. Here we show that the internal organization and dynamics of rings are different from sarcomeres and distinct in different cell types. Using micro-cavities to orient rings in single focal planes, we find in mammalian cells a transition from a homogeneous distribution to a periodic pattern of myosin clusters at the onset of constriction. In contrast, in fission yeast, myosin clusters rotate prior to and during constriction. Theoretical analysis indicates that both patterns result from acto-myosin self-organization and reveals differences in the respective stresses. These findings suggest distinct functional roles for rings: contraction in mammalian cells and transport in fission yeast. Thus self-organization under different conditions may be a generic feature for regulating morphogenesis in vivo. PMID:27363521

  6. Ring cycle for dilating and constricting the nuclear pore

    PubMed Central

    Solmaz, Sozanne R.; Blobel, Günter; Melčák, Ivo

    2013-01-01

    We recently showed that the three “channel” nucleoporins, Nup54, Nup58, and Nup62, interact with each other through only four distinct sites and established the crystal structures of the two resulting “interactomes,” Nup54•Nup58 and Nup54•Nup62. We also reported instability of the Nup54•Nup58 interactome and previously determined the atomic structure of the relevant Nup58 segment by itself, demonstrating that it forms a twofold symmetric tetramer. Here, we report the crystal structure of the relevant free Nup54 segment and show that it forms a tetrameric, helical bundle that is structurally “conditioned” for instability by a central patch of polar hydrogen-bonded residues. Integrating these data with our previously reported results, we propose a “ring cycle” for dilating and constricting the nuclear pore. In essence, three homooligomeric rings, one consisting of eight modules of Nup58 tetramers, and two, each consisting of eight modules of Nup54 tetramers, are stacked in midplane and characterize a constricted pore of 10- to 20-nm diameter. In going to the dilated state, segments of one Nup58 and two Nup54 tetrameric modules reassort into a dodecameric module, eight of which form a single, heterooligomeric midplane ring, which is flexible in a diameter range of 40–50 nm. The ring cycle would be regulated by phenylalanine–glycine regions (“FG repeats”) of channel nups. Akin to ligand-gated channels, the dilated state of the midplane ring may be stabilized by binding of [cargo•transport-factor] complexes to FG repeats, thereby linking the ratio of constricted to dilated nuclear pores to cellular transport need. PMID:23479651

  7. Myeloid Mineralocorticoid Receptor Deficiency Inhibits Aortic Constriction-Induced Cardiac Hypertrophy in Mice

    PubMed Central

    Zheng, Xiao Jun; Zhang, Wu Chang; Sun, Xue Nan; Yang, Qing Zhen; Ma, Shu Min; Huang, Baozhuan; Berger, Stefan; Wang, Wang; Wu, Yong; Yu, Ying; Duan, Sheng Zhong; Mortensen, Richard M.

    2014-01-01

    Mineralocorticoid receptor (MR) blockade has been shown to suppress cardiac hypertrophy and remodeling in animal models of pressure overload (POL). This study aims to determine whether MR deficiency in myeloid cells modulates aortic constriction-induced cardiovascular injuries. Myeloid MR knockout (MMRKO) mice and littermate control mice were subjected to abdominal aortic constriction (AAC) or sham operation. We found that AAC-induced cardiac hypertrophy and fibrosis were significantly attenuated in MMRKO mice. Expression of genes important in generating reactive oxygen species was decreased in MMRKO mice, while that of manganese superoxide dismutase increased. Furthermore, expression of genes important in cardiac metabolism was increased in MMRKO hearts. Macrophage infiltration in the heart was inhibited and expression of inflammatory genes was decreased in MMRKO mice. In addition, aortic fibrosis and inflammation were attenuated in MMRKO mice. Taken together, our data indicated that MR deficiency in myeloid cells effectively attenuated aortic constriction-induced cardiac hypertrophy and fibrosis, as well as aortic fibrosis and inflammation. PMID:25354087

  8. Mycotic aortic arch aneurysm coexistent with constrictive pericarditis: is surgery a dangerous resort?

    PubMed Central

    Yu, Peter S. Y.; Yu, Simon C. H.; Chu, Cheuk-Man; Kwok, Micky W. T.; Lam, Yuk-Hoi; Underwood, Malcolm J.

    2016-01-01

    An elderly man presented with fever and evidence of Salmonella infection, and was diagnosed to have coexisting constrictive pericarditis and mycotic aneurysm of the aortic arch. Pericardiectomy was performed under cardiopulmonary bypass with good result. To avoid deep hypothermic circulatory arrest, an aorto-brachiocephalic bypass, instead of total arch replacement, was performed. This was followed by a staged carotid-carotid bypass, thoracic endovascular stent graft placement. He was subsequently treated with prolonged antibiotics, and inflammatory marker normalized afterwards. He was last seen well 2 years after the operation. Follow-up computer tomography (CT) scan at 18 months post-op showed no evidence of endoleak or fistulation. Our case demonstrated that a hybrid treatment of open pericardiectomy and aortic debranching followed by thoracic endovascular stent graft placement is feasible and associated with satisfactory mid-term outcome. PMID:27621905

  9. Mycotic aortic arch aneurysm coexistent with constrictive pericarditis: is surgery a dangerous resort?

    PubMed Central

    Yu, Peter S. Y.; Yu, Simon C. H.; Chu, Cheuk-Man; Kwok, Micky W. T.; Lam, Yuk-Hoi; Underwood, Malcolm J.

    2016-01-01

    An elderly man presented with fever and evidence of Salmonella infection, and was diagnosed to have coexisting constrictive pericarditis and mycotic aneurysm of the aortic arch. Pericardiectomy was performed under cardiopulmonary bypass with good result. To avoid deep hypothermic circulatory arrest, an aorto-brachiocephalic bypass, instead of total arch replacement, was performed. This was followed by a staged carotid-carotid bypass, thoracic endovascular stent graft placement. He was subsequently treated with prolonged antibiotics, and inflammatory marker normalized afterwards. He was last seen well 2 years after the operation. Follow-up computer tomography (CT) scan at 18 months post-op showed no evidence of endoleak or fistulation. Our case demonstrated that a hybrid treatment of open pericardiectomy and aortic debranching followed by thoracic endovascular stent graft placement is feasible and associated with satisfactory mid-term outcome.

  10. Mycotic aortic arch aneurysm coexistent with constrictive pericarditis: is surgery a dangerous resort?

    PubMed

    Yu, Peter S Y; Yu, Simon C H; Chu, Cheuk-Man; Kwok, Micky W T; Lam, Yuk-Hoi; Underwood, Malcolm J; Wong, Randolph H L

    2016-08-01

    An elderly man presented with fever and evidence of Salmonella infection, and was diagnosed to have coexisting constrictive pericarditis and mycotic aneurysm of the aortic arch. Pericardiectomy was performed under cardiopulmonary bypass with good result. To avoid deep hypothermic circulatory arrest, an aorto-brachiocephalic bypass, instead of total arch replacement, was performed. This was followed by a staged carotid-carotid bypass, thoracic endovascular stent graft placement. He was subsequently treated with prolonged antibiotics, and inflammatory marker normalized afterwards. He was last seen well 2 years after the operation. Follow-up computer tomography (CT) scan at 18 months post-op showed no evidence of endoleak or fistulation. Our case demonstrated that a hybrid treatment of open pericardiectomy and aortic debranching followed by thoracic endovascular stent graft placement is feasible and associated with satisfactory mid-term outcome. PMID:27621905

  11. Classification of the pattern of intrauterine amputations of the upper limb in constriction ring syndrome.

    PubMed

    Al-Qattan, M M

    2000-06-01

    Twenty patients with congenital upper limb amputations caused by constriction rings were reviewed to classify the pattern of these amputations. In the 20 patients studied, 31 upper limbs had congenital amputations. The pattern of amputation was classified into three types. Proximal upper limb amputation was considered type I and was only seen in one limb. The most common pattern of amputation was digital amputation associated with "coning" or "superimposition" of the digits (type II) and was seen in 20 hands. Type II amputations were subclassified according to the involvement of all, ulnar, radial, or central digits by the constriction ring. In type III amputations (N = 10 limbs), there was no associated coning or superimposition of the digits. This type of amputation was subclassified into type IIIA (multiple-digit amputations within the same hand) and type III B (single-digit amputation). Associated anomalies are reviewed and the pathogenesis of constriction rings is discussed.

  12. Vasorelaxant Effect of Osterici Radix Ethanol Extract on Rat Aortic Rings

    PubMed Central

    Lee, Kyungjin; Park, Geunyong; Ham, Inhye; Yang, Gabsik; Lee, Mihwa; Bu, Youngmin; Kim, Hocheol; Choi, Ho-Young

    2013-01-01

    The root of Ostericum koreanum Maximowicz has been used as a traditional medicine called “Kanghwal” in Korea (or “Qianghuo” in China). The purpose of this study was to investigate the vasorelaxant activity and mechanism of action of an ethanol extract of the O. koreanum root (EOK). We used isolated rat aortic rings to assess the effects of EOK on various vasorelaxant or vasoconstriction factors. EOK induced vasorelaxation in phenylephrine hydrochloride (PE) or KCl precontracted aortic rings in a concentration-dependent manner. However, the vasorelaxant effects of EOK on endothelium-intact aortic rings were reduced by pretreatment with L-NAME or methylene blue. In Ca2+-free Krebs-Henseleit solution, pretreatment with EOK (0.3 mg/mL) completely inhibited PE-induced constriction. In addition, EOK (0.3 mg/mL) also completely inhibited vasoconstriction induced by supplemental Ca2+ in aortic rings that were precontracted with PE or KCl. Furthermore, the EOK-induced vasorelaxation in PE-contracted aortic rings was inhibited by preincubation with nifedipine. These results indicate that the vasorelaxant effects of EOK are responsible for the induction of NO formation from L-Arg and NO-cGMP pathways, blockage of the extracellular Ca2+ entry via the receptor-operative Ca2+ channel and voltage-dependent calcium channel, and blockage of sarcoplasmic reticulum Ca2+ release via the inositol triphosphate pathway. PMID:24204390

  13. Adult presentation with vascular ring due to double aortic arch.

    PubMed

    Kafka, Henryk; Uebing, Anselm; Mohiaddin, Raad

    2006-11-01

    This is a case report on the use of cardiovascular magnetic resonance imaging to diagnose vascular ring due to double aortic arch in an adult presenting with an abnormal chest X-ray. The experience in this case and the literature review identify the benefits of using cardiovascular magnetic resonance imaging to clarify complex aortic arch anatomy.

  14. Constriction model of actomyosin ring for cytokinesis by fission yeast using a two-state sliding filament mechanism

    NASA Astrophysics Data System (ADS)

    Jung, Yong-Woon; Mascagni, Michael

    2014-09-01

    We developed a model describing the structure and contractile mechanism of the actomyosin ring in fission yeast, Schizosaccharomyces pombe. The proposed ring includes actin, myosin, and α-actinin, and is organized into a structure similar to that of muscle sarcomeres. This structure justifies the use of the sliding-filament mechanism developed by Huxley and Hill, but it is probably less organized relative to that of muscle sarcomeres. Ring contraction tension was generated via the same fundamental mechanism used to generate muscle tension, but some physicochemical parameters were adjusted to be consistent with the proposed ring structure. Simulations allowed an estimate of ring constriction tension that reproduced the observed ring constriction velocity using a physiologically possible, self-consistent set of parameters. Proposed molecular-level properties responsible for the thousand-fold slower constriction velocity of the ring relative to that of muscle sarcomeres include fewer myosin molecules involved, a less organized contractile configuration, a low α-actinin concentration, and a high resistance membrane tension. Ring constriction velocity is demonstrated as an exponential function of time despite a near linear appearance. We proposed a hypothesis to explain why excess myosin heads inhibit constriction velocity rather than enhance it. The model revealed how myosin concentration and elastic resistance tension are balanced during cytokinesis in S. pombe.

  15. Constriction model of actomyosin ring for cytokinesis by fission yeast using a two-state sliding filament mechanism

    SciTech Connect

    Jung, Yong-Woon; Mascagni, Michael

    2014-09-28

    We developed a model describing the structure and contractile mechanism of the actomyosin ring in fission yeast, Schizosaccharomyces pombe. The proposed ring includes actin, myosin, and α-actinin, and is organized into a structure similar to that of muscle sarcomeres. This structure justifies the use of the sliding-filament mechanism developed by Huxley and Hill, but it is probably less organized relative to that of muscle sarcomeres. Ring contraction tension was generated via the same fundamental mechanism used to generate muscle tension, but some physicochemical parameters were adjusted to be consistent with the proposed ring structure. Simulations allowed an estimate of ring constriction tension that reproduced the observed ring constriction velocity using a physiologically possible, self-consistent set of parameters. Proposed molecular-level properties responsible for the thousand-fold slower constriction velocity of the ring relative to that of muscle sarcomeres include fewer myosin molecules involved, a less organized contractile configuration, a low α-actinin concentration, and a high resistance membrane tension. Ring constriction velocity is demonstrated as an exponential function of time despite a near linear appearance. We proposed a hypothesis to explain why excess myosin heads inhibit constriction velocity rather than enhance it. The model revealed how myosin concentration and elastic resistance tension are balanced during cytokinesis in S. pombe.

  16. Congenital constriction ring of limbs in subjects with history of maternal substance use.

    PubMed

    Malik, Sajid; Lal, Karmoon; Fatima, Noreen Ghulam; Samo, Ayaz; Haque, Sayedul

    2015-05-01

    Congenital Constriction Ring (CCR) is a rare malformation which manifests itself in the form of ring-like constrictive bands. Due to its heterogeneous nature, its etiology remains unclear. Here, we present a series of seven independent individuals afflicted with CCR, which primarily involved the digits. The phenotypic manifestations included terminal phalangeal reduction, anonychia, digit hypoplasia, and acrosyndactyly. Mesoaxial digits in hands and preaxial digits in feet were most frequently affected. Camptodactyly and clubfoot were witnessed in four and one subject, respectively. Curiously, mothers of six of these subjects revealed that they consumed copious amounts of Multani mitti(Fuller's clay) and/or Naswar(nonsmoke-tobacco), during their respective pregnancies. Maternal substance use during pregnancy is not an unusual practice, however, its relationship with CCR as pregnancy outcome remains unexplored. Case-control studies are warranted to elucidate the relationship between the exposure to these substances and the etiology of CCR and/or other limb defects in the offspring. PMID:26008671

  17. Magnesium and diltiazem relaxes phenylephrine-precontracted rat aortic rings

    PubMed Central

    Dogan, Mustafa; Peker, Recep O.; Donmez, Soner; Gokalp, Osman

    2012-01-01

    Perioperative vasospasm during cardiovascular surgery is a challenging problem. Several vasodilator agents are frequently utilized for its prevention in surgical practice. Magnesium and diltiazem both have known potential vasorelaxant effects. We planned to compare the efficacy of diltiazem and magnesium in relieving phenylephrine-precontracted rat aortic rings. Ten young adult female Wistar albino rats weighing 230–260 g were used in this study. The aortic rings in the organ bath equilibrated and reached their baseline tension. Precontraction was induced by 0.001 mmol/l phenylephrine and cumulative concentration–relaxation curves were obtained by consecutively increasing the addition of either diltiazem (10−6-0.1 mmol/l) or magnesium (0.1–10 mmol/l). The mean maximal relaxation responses observed by diltiazem and magnesium on separate aortic rings were 90 ± 3 and 53 ± 2%, respectively. The calculated EC50 of diltiazem was 0.01035 mmol/l, whereas the EC50 of magnesium was 4.064 mmol/l (P < 0.05). Both magnesium and diltiazem produced vasorelaxation on phenylephrine-precontracted rat aortic rings in this study, but the potency of diltiazem regarding the EC50 value was significantly higher than that of magnesium. Magnesium could be a candidate together with diltiazem to inhibit vasospasm on arterial grafts during coronary bypass surgery. PMID:22523136

  18. A Multi-layered Protein Network Stabilizes the Escherichia coli FtsZ-ring and Modulates Constriction Dynamics

    PubMed Central

    Buss, Jackson; Coltharp, Carla; Shtengel, Gleb; Yang, Xinxing; Hess, Harald; Xiao, Jie

    2015-01-01

    The prokaryotic tubulin homolog, FtsZ, forms a ring-like structure (FtsZ-ring) at midcell. The FtsZ-ring establishes the division plane and enables the assembly of the macromolecular division machinery (divisome). Although many molecular components of the divisome have been identified and their interactions extensively characterized, the spatial organization of these proteins within the divisome is unclear. Consequently, the physical mechanisms that drive divisome assembly, maintenance, and constriction remain elusive. Here we applied single-molecule based superresolution imaging, combined with genetic and biophysical investigations, to reveal the spatial organization of cellular structures formed by four important divisome proteins in E. coli: FtsZ, ZapA, ZapB and MatP. We show that these interacting proteins are arranged into a multi-layered protein network extending from the cell membrane to the chromosome, each with unique structural and dynamic properties. Further, we find that this protein network stabilizes the FtsZ-ring, and unexpectedly, slows down cell constriction, suggesting a new, unrecognized role for this network in bacterial cell division. Our results provide new insight into the structure and function of the divisome, and highlight the importance of coordinated cell constriction and chromosome segregation. PMID:25848771

  19. DL0805-2, a novel indazole derivative, relaxes angiotensin II-induced contractions of rat aortic rings by inhibiting Rho kinase and calcium fluxes

    PubMed Central

    Yuan, Tian-yi; Chen, Yu-cai; Zhang, Hui-fang; Li, Li; Jiao, Xiao-zhen; Xie, Ping; Fang, Lian-hua; Du, Guan-hua

    2016-01-01

    Aim: DL0805-2 [N-(1H-indazol-5-yl)-1-(4-methylbenzyl) pyrrolidine-3-carboxamide] is a DL0805 derivative with more potent vasorelaxant activity and lower toxicity. This study was conducted to investigate the vasorelaxant mechanisms of DL0805-2 on angiotensin II (Ang II)-induced contractions of rat thoracic aortic rings in vitro. Methods: Rat thoracic aortic rings and rat aortic vascular smooth muscle cells (VSMCs) were pretreated with DL0805-2, and then stimulated with Ang II. The tension of the aortic rings was measured through an isometric force transducer. Ang II-induced protein phosphorylation, ROS production and F-actin formation were assessed with Western blotting and immunofluorescence assays. Intracellular free Ca2+ concentrations were detected with Fluo-3 AM. Results: Pretreatment with DL0805-2 (1–100 μmol/L) dose-dependently inhibited the constrictions of the aortic rings induced by a single dose of Ang II (10−7 mol/L) or accumulative addition of Ang II (10−10–10−7 mol/L). The vasodilatory effect of DL0805-2 was independent of endothelium. In the aortic rings, pretreatment with DL0805-2 (1, 3, and 10 μmol/L) suppressed Ang II-induced Ca2+ influx and intracellular Ca2+ mobilization, and Ang II-induced phosphorylation of two substrates of Rho kinase (MLC and MYPT1). In VSMCs, pretreatment with DL0805-2 (1, 3, and 10 μmol/L) also suppressed Ang II-induced Ca2+ fluxes and phosphorylation of MLC and MYPT1. In addition, pretreatment with DL0805-2 attenuated ROS production and F-actin formation in the cells. Conclusion: DL0805-2 exerts a vasodilatory action in rat aortic rings through inhibiting the Rho/ROCK pathway and calcium fluxes. PMID:27041459

  20. c-Myc alters substrate utilization and O-GlcNAc protein posttranslational modifications without altering cardiac function during early aortic constriction

    SciTech Connect

    Ledee, Dolena; Smith, Lincoln; Bruce, Margaret; Kajimoto, Masaki; Isern, Nancy; Portman, Michael A.; Olson, Aaron K.; Bertrand, Luc

    2015-08-12

    Pressure overload cardiac hypertrophy alters substrate metabolism. Prior work showed that myocardial inactivation of c-Myc (Myc) attenuated hypertrophy and decreased expression of metabolic genes after aortic constriction. Accordingly, we hypothesize that Myc regulates substrate preferences for the citric acid cycle during pressure overload hypertrophy from transverse aortic constriction (TAC) and that these metabolic changes impact cardiac function and growth. To test this hypothesis, we subjected mice with cardiac specific, inducible Myc inactivation (MycKO-TAC) and non-transgenic littermates (Cont-TAC) to transverse aortic constriction (TAC; n=7/group). A separate group underwent sham surgery (Sham, n=5). After two weeks, function was measured in isolated working hearts along with substrate fractional contributions to the citric acid cycle by using perfusate with 13C labeled mixed fatty acids, lactate, ketone bodies and unlabeled glucose and insulin. Cardiac function was similar between groups after TAC although +dP/dT and -dP/dT trended towards improvement in MycKO-TAC versus Cont-TAC. Compared to Sham, Cont-TAC had increased free fatty acid fractional contribution with a concurrent decrease in unlabeled (predominately glucose) contribution. The changes in free fatty acid and unlabeled fractional contributions were abrogated by Myc inactivation during TAC (MycKO-TAC). Additionally, protein posttranslational modification by O-GlcNAc was significantly greater in Cont-TAC versus both Sham and MycKO-TAC. Lastly, Myc alters substrate preferences for the citric acid cycle during early pressure overload hypertrophy without negatively affecting cardiac function. Myc also affects protein posttranslational modifications by O-GlcNAc during hypertrophy.

  1. c-Myc alters substrate utilization and O-GlcNAc protein posttranslational modifications without altering cardiac function during early aortic constriction

    DOE PAGES

    Ledee, Dolena; Smith, Lincoln; Bruce, Margaret; Kajimoto, Masaki; Isern, Nancy; Portman, Michael A.; Olson, Aaron K.; Bertrand, Luc

    2015-08-12

    Pressure overload cardiac hypertrophy alters substrate metabolism. Prior work showed that myocardial inactivation of c-Myc (Myc) attenuated hypertrophy and decreased expression of metabolic genes after aortic constriction. Accordingly, we hypothesize that Myc regulates substrate preferences for the citric acid cycle during pressure overload hypertrophy from transverse aortic constriction (TAC) and that these metabolic changes impact cardiac function and growth. To test this hypothesis, we subjected mice with cardiac specific, inducible Myc inactivation (MycKO-TAC) and non-transgenic littermates (Cont-TAC) to transverse aortic constriction (TAC; n=7/group). A separate group underwent sham surgery (Sham, n=5). After two weeks, function was measured in isolated workingmore » hearts along with substrate fractional contributions to the citric acid cycle by using perfusate with 13C labeled mixed fatty acids, lactate, ketone bodies and unlabeled glucose and insulin. Cardiac function was similar between groups after TAC although +dP/dT and -dP/dT trended towards improvement in MycKO-TAC versus Cont-TAC. Compared to Sham, Cont-TAC had increased free fatty acid fractional contribution with a concurrent decrease in unlabeled (predominately glucose) contribution. The changes in free fatty acid and unlabeled fractional contributions were abrogated by Myc inactivation during TAC (MycKO-TAC). Additionally, protein posttranslational modification by O-GlcNAc was significantly greater in Cont-TAC versus both Sham and MycKO-TAC. Lastly, Myc alters substrate preferences for the citric acid cycle during early pressure overload hypertrophy without negatively affecting cardiac function. Myc also affects protein posttranslational modifications by O-GlcNAc during hypertrophy.« less

  2. Demonstration of independent roles of proximal tubular reabsorption and intratubular load in the phenomenon of glomerulotubular balance during aortic constriction in the rat

    PubMed Central

    Buentig, Wolf E.; Earley, Laurence E.

    1971-01-01

    The mechanism of glomerulotubular balance was investigated by microperfusion of the rat proximal tubule at two different rates before and after contriction of the aorta sufficient to produce a 50% reduction in whole kidney filtration rate and plasma flow. At a perfusion rate of 28 nl/min the absolute rate of proximal tubular reabsorption averaged 4.80±0.28 nl/mm·min in the absence of aortic constriction. Reducing the perfusion rate by one-half resulted in only a 22% decrease in the absolute rate of reabsorption, and imbalance between load and reabsorption resulted as fractional reabsorption of the perfused volume increased from 0.56 to 0.83 at 3 mm length of perfused tubule. These observations support other studies indicating that changing the load presented to the individual proximal tubule does not change reabsorptive rate sufficiently to result in glomerulotubular balance. Aortic constriction decreased the absolute rate of proximal tubular reabsorption approximately 50%, resulting in imbalance between load and reabsorption at the higher perfusion rate (fractional reabsorption of the perfused volume fell to 0.23 at 3 mm). Thus, the decrease in proximal tubular reabsorption necessary for glomerulotubular balance will occur independent of a change in the load presented for reabsorption. Balance between load and reabsorption was produced artificially by combining aortic constriction and a reduction in perfusion rate proportional to the reduction in whole kidney filtration rate. Mathematical analysis of the data suggests that the absolute rate of reabsorption along the accessible length of the proximal tubule is constant and is not proportional to the volume of fluid reaching a given site. Thus, there appears to be no contribution to glomerulotubular balance of any intra- or extratubular mechanism directly coupling load and the rate of proximal tubular reabsorption. It is concluded that glomerulotubular balance during aortic constriction is a consequence of

  3. A mutation in the converter subdomain of Aspergillus nidulans MyoB blocks constriction of the actomyosin ring in cytokinesis.

    PubMed

    Hill, Terry W; Jackson-Hayes, Loretta; Wang, Xiao; Hoge, Brianna L

    2015-02-01

    We have identified a mutant allele of the Aspergillus nidulans homologue of myosin II (myoB; AN4706), which prevents normal septum formation. This is the first reported myosin II mutation in a filamentous fungus. Strains expressing the myoB(G843D) allele produce mainly aberrant septa at 30 °C and are completely aseptate at temperatures above 37 °C. Conidium formation is greatly reduced at 30 °C and progressively impaired with increasing temperature. Sequencing of the myoB(G843D) allele identified a point mutation predicted to result in a glycine-to-aspartate amino acid substitution at residue 843 in the myosin II converter domain. This residue is conserved in all fungal, plant, and animal myosin sequences that we have examined. The mutation does not prevent localization of the myoB(G843D) gene product to contractile rings, but it does block ring constriction. MyoB(G843D) rings at sites of abortive septation disassemble after an extended period and dissipate into the cytoplasm. During contractile ring formation, both wild type and mutant MyoB::GFP colocalize with actin--an association that begins at the pre-ring "string" stage. Down-regulation of wild-type myoB expression under control of the alcA promoter blocks septation but does not prevent actin from aggregating at putative septation sites--the actin rings, however, do not fully coalesce. Both septation and targeting of MyoB are blocked by disruption of filamentous actin using latrunculin B. We propose a model in which myosin assembly at septation sites depends upon the presence of F-actin, but assembly of the actin component of contractile rings depends upon normal levels of myosin only for the final stages of ring compaction.

  4. Administration of antioxidant peptide SS-31 attenuates transverse aortic constriction-induced pulmonary arterial hypertension in mice

    PubMed Central

    Lu, Hung-i; Huang, Tien-hung; Sung, Pei-hsun; Chen, Yung-lung; Chua, Sarah; Chai, Han-yan; Chung, Sheng-ying; Liu, Chu-feng; Sun, Cheuk-kwan; Chang, Hsueh-wen; Zhen, Yen-yi; Lee, Fan-yen; Yip, Hon-kan

    2016-01-01

    Aim: Antioxidant peptide SS-31 is a class of cell-permeable small peptides, which selectively resides on the inner mitochondrial membrane and possesses intrinsic mitochondrial protective capacities. In this study we investigated the therapeutic effects of antioxidant peptide SS-31 on transverse aortic constriction (TAC)-induced pulmonary arterial hypertension (PAH) in a murine model. Methods: Adult male mice were divided into 3 groups: sham-operated mice, TAC mice, and TAC+SS-31 mice that underwent TAC surgery and received SS-31 (2 mg/d, ip) for 60 d. The right ventricular systolic blood pressure (RVSBP) was measured on d 60 prior to sacrificing the mice; then their right heart and lung tissues were collected for histological and biochemical examinations. Lung injury scores were defined by the increased crowded area and decreased number of alveolar sacs. Results: TAC mice showed significantly higher RVSBP compared with sham-operated mice, the elevation was substantially suppressed in TAC+SS-31 mice. The same pattern of changes was found in pulmonary levels of oxidative stress proteins (NOX-1/NOX-2/oxidized proteins), cytosolic cytochrome c, biomarkers related to inflammation (MMP-9/TNF-α/iNOS), calcium overload index (TRPC1, 2, 4, 6), apoptosis (mitochondrial BAX, cleaved caspase 3/PARP), fibrosis (Smad3/TGF-β), hypoxic (HIF-1α), DNA damage (γ-H2AX) and endothelial function (eNOS/ET-1R), as well as in lung injury score, number of muscularized vessels in lungs, number of TRPC1+ and HIF-1α+ cells in pulmonary artery, and number of γ-H2AX+ and Ki-67+ cells in lung parenchyma. An opposite pattern of changes was observed in pulmonary anti-fibrotic markers (Smad1/5, BMP-2), number of small vessels, and number of alveolar sacs. In contrast, the levels of antioxidant proteins (HO-1/NQO-1/GR/GPx) in lung parenchyma were progressively and significantly increased from sham-operated mice, TAC mice to TAC+SS-31 mice. Conclusion: Antioxidant peptide SS-31 administration

  5. The aortic ring model of angiogenesis: a quarter century of search and discovery

    PubMed Central

    Nicosia, R F

    2009-01-01

    The aortic ring model has become one of the most widely used methods to study angiogenesis and its mechanisms. Many factors have contributed to its popularity including reproducibility, cost effectiveness, ease of use and good correlation with in vivo studies. In this system aortic rings embedded in biomatrix gels and cultured under chemically defined conditions generate arborizing vascular outgrowths which can be stimulated or inhibited with angiogenic regulators. Originally based on the rat aorta, the aortic ring model was later adapted to the mouse for the evaluation of specific molecular alterations in genetically modified animals. Viral transduction of the aortic rings has enabled investigators to overexpress genes of interest in the aortic cultures. Experiments on angiogenic mechanisms have demonstrated that formation of neovessels in aortic cultures is regulated by macrophages, pericytes and fibroblasts through a complex molecular cascade involving growth factors, inflammatory cytokines, axonal guidance cues, extracellular matrix (ECM) molecules and matrix-degrading proteolytic enzymes. These studies have shown that endothelial sprouting can be effectively blocked by depleting the aortic explants of macrophages or by interfering with the angiogenic cascade at multiple levels including growth factor signalling, cell adhesion and proteolytic degradation of the ECM. In this paper, we review the literature in this field and retrace the journey from our first morphological descriptions of the aortic outgrowths to the latest breakthroughs in the cellular and molecular regulation of aortic vessel growth and regression. PMID:19725916

  6. Procyanidin C1 Causes Vasorelaxation Through Activation of the Endothelial NO/cGMP Pathway in Thoracic Aortic Rings

    PubMed Central

    Byun, Eui-Baek; Sung, Nak-Yun; Yang, Mi-So; Song, Du-Sup; Byun, Eui-Hong; Kim, Jae-Kyung; Park, Jong-Heum; Song, Beom-Seok; Lee, Ju-Woon; Park, Sang-Hyun; Byun, Myung-Woo

    2014-01-01

    Abstract The aim of this study was to clarify the efficacy of procyanidin C1 (Pro C1) for modulating vascular tone. Pro C1 induced a potent vasorelaxant effect on phenylephrine-constricted endothelium-intact thoracic aortic rings, but had no effect on denuded thoracic aortic rings. Moreover, Pro C1 caused a significant increase in nitric oxide (NO) production in endothelial cells. Pro C1-induced vasorelaxation and Pro C1-induced NO production were significantly decreased in the presence of a nonspecific potassium channel blocker (tetraethylammonium chloride [TEA]), an endothelial NO synthase inhibitor (NG-monomethyl-L-arginine [L-NMMA]), and a store-operated calcium entry inhibitor (2-aminoethyl diphenylborinate [2-APB]). Pro C1-induced vasorelaxation was also completely abolished by an inhibitor of soluble guanyl cyclase, which suggests that the Pro C1 effects observed involved cyclic guanosine monophosphate (cGMP) production. Interestingly, Pro C1 significantly enhanced basal cGMP levels. Taken together, these results indicate that Pro C1-induced vasorelaxation is associated with the activation of the calcium-dependent NO/cGMP pathway, involving potassium channel activation. Thus, Pro C1 may represent a novel and potentially therapeutically relevant compound for the treatment of cardiovascular diseases. PMID:24971771

  7. c-Myc Alters Substrate Utilization and O-GlcNAc Protein Posttranslational Modifications without Altering Cardiac Function during Early Aortic Constriction

    PubMed Central

    Ledee, Dolena; Smith, Lincoln; Bruce, Margaret; Kajimoto, Masaki; Isern, Nancy; Portman, Michael A.; Olson, Aaron K.

    2015-01-01

    Hypertrophic stimuli cause transcription of the proto-oncogene c-Myc (Myc). Prior work showed that myocardial knockout of c-Myc (Myc) attenuated hypertrophy and decreased expression of metabolic genes after aortic constriction. Accordingly, we assessed the interplay between Myc, substrate oxidation and cardiac function during early pressure overload hypertrophy. Mice with cardiac specific, inducible Myc knockout (MycKO-TAC) and non-transgenic littermates (Cont-TAC) were subjected to transverse aortic constriction (TAC; n = 7/group). Additional groups underwent sham surgery (Cont-Sham and MycKO-Sham, n = 5 per group). After two weeks, function was measured in isolated working hearts along with substrate fractional contributions to the citric acid cycle by using perfusate with 13C labeled mixed fatty acids, lactate, ketone bodies and unlabeled glucose and insulin. Cardiac function was similar between groups after TAC although +dP/dT and -dP/dT trended towards improvement in MycKO-TAC versus Cont-TAC. In sham hearts, Myc knockout did not affect cardiac function or substrate preferences for the citric acid cycle. However, Myc knockout altered fractional contributions during TAC. The unlabeled fractional contribution increased in MycKO-TAC versus Cont-TAC, whereas ketone and free fatty acid fractional contributions decreased. Additionally, protein posttranslational modifications by O-GlcNAc were significantly greater in Cont-TAC versus both Cont-Sham and MycKO-TAC. In conclusion, Myc alters substrate preferences for the citric acid cycle during early pressure overload hypertrophy without negatively affecting cardiac function. Myc also affects protein posttranslational modifications by O-GlcNAc during hypertrophy, which may regulate Myc-induced metabolic changes. PMID:26266538

  8. MCP-1 promotes mural cell recruitment during angiogenesis in the aortic ring model.

    PubMed

    Aplin, Alfred C; Fogel, Eric; Nicosia, Roberto F

    2010-09-01

    Rings of rat or mouse aorta embedded in collagen gels produce angiogenic outgrowths in response to the injury of the dissection procedure. Aortic outgrowths are composed of branching endothelial tubes and surrounding mural cells. Mural cells emerge following endothelial sprouting and gradually increase during the maturation of the neovessels. Treatment of aortic cultures with angiopoietin-1 (Ang-1), an angiogenic factor implicated in vascular maturation and remodeling, stimulates the mural cell recruitment process. Ang-1 induces expression of many cytokines and chemokines including monocyte chemotactic protein-1 (MCP-1). Inhibition of p38 MAP kinase, a signaling molecule required for mural cell recruitment, blocks Ang1-induced MCP-1 expression. Recombinant MCP-1 dose-dependently increases mural cell number while an anti-MCP-1 blocking antibody reduces it. In addition, antibody mediated neutralization of MCP-1 abrogates the stimulatory effect of Ang-1 on mural cell recruitment. Aortic rings from genetically modified mice deficient in MCP-1 or its receptor CCR2 have fewer mural cells than controls. MCP-1 deficiency also impairs the mural cell recruitment activity of Ang-1. Our studies indicate that spontaneous and Ang1-induced mural cell recruitment in the aortic ring of model of angiogenesis are in part mediated by MCP-1. These results implicate MCP-1 as one of the mediators of mural cell recruitment in the aortic ring model, and suggest that chemokine pathways may contribute to the assembly of the vessel wall during the angiogenesis response to injury.

  9. Multidetector Computed Tomography for Congenital Anomalies of the Aortic Arch: Vascular Rings.

    PubMed

    García-Guereta, Luis; García-Cerro, Estefanía; Bret-Zurita, Montserrat

    2016-07-01

    The development of multidetector computed tomography has triggered a revolution in the study of the aorta and other large vessels and has replaced angiography in the diagnosis of congenital anomalies of the aortic arch, particularly vascular rings. The major advantage of multidetector computed tomography is that it permits clear 3-dimensional assessment of not only vascular structures, but also airway and esophageal compression. The current update aims to summarize the embryonic development of the aortic arch and the developmental anomalies leading to vascular ring formation and to discuss the current diagnostic and therapeutic role of multidetector computed tomography in this field.

  10. Mechanism of the relaxant effect of rosuvastatin lactone on rat aortic rings.

    PubMed

    Ana Cecilia, Polanco-Ponce; Victor Manuel, Perez-Alvarez; Isabel, Wens-Flores; Enrique, Castillo-Henkel; Pedro, Lopez-Sanchez; Jorge Skiold, Lopez-Canales; Maria del Carmen, Castillo-Hernandez; Carlos, Castillo-Henkel

    2012-01-01

    The relaxant effect of the lactone of rosuvastatin was evaluated on aortic rings from male Wistar rats (250-300 g) with and without endothelium, precontracted with 1.0 microM phenylephrine. The lactone presented a greater potency than rosuvastatin in relaxing aortic rings. Unlike rosuvastatin, the effect of its lactone was endothelium-independent. Pretreatment with either indomethacin (10 microM) or mevalonate (1 mM) did not inhibit the relaxant effect of the lactone. L-NAME (10 microM), 1400 W (10 microM), or tetraethylammonium (TEA, 10 mM) partially inhibited the relaxant effect of the lactone on endothelium-denuded aortic rings. However, cycloheximide (10 microM) or the combination of TEA plus L-NAME completely inhibited the relaxant effect. The NOS-2 was only present in endothelium-denuded aortic rings, as demonstrated by immunoblot with lactone treated rings. In conclusion, rosuvastatin was associated with a relaxant effect dependent on both endothelium and HMG-CoA reductase in rat aorta, whereas the lactone exhibited an endothelium and HMG-CoA reductase-independent relaxant effect. Both nitric oxide produced by NOS-2 and K+ channels are involved in the relaxant effect of the lactone.

  11. The F-actin bundler α-actinin Ain1 is tailored for ring assembly and constriction during cytokinesis in fission yeast

    PubMed Central

    Li, Yujie; Christensen, Jenna R.; Homa, Kaitlin E.; Hocky, Glen M.; Fok, Alice; Sees, Jennifer A.; Voth, Gregory A.; Kovar, David R.

    2016-01-01

    The actomyosin contractile ring is a network of cross-linked actin filaments that facilitates cytokinesis in dividing cells. Contractile ring formation has been well characterized in Schizosaccharomyces pombe, in which the cross-linking protein α-actinin SpAin1 bundles the actin filament network. However, the specific biochemical properties of SpAin1 and whether they are tailored for cytokinesis are not known. Therefore we purified SpAin1 and quantified its ability to dynamically bind and bundle actin filaments in vitro using a combination of bulk sedimentation assays and direct visualization by two-color total internal reflection fluorescence microscopy. We found that, while SpAin1 bundles actin filaments of mixed polarity like other α-actinins, SpAin1 has lower bundling activity and is more dynamic than human α-actinin HsACTN4. To determine whether dynamic bundling is important for cytokinesis in fission yeast, we created the less dynamic bundling mutant SpAin1(R216E). We found that dynamic bundling is critical for cytokinesis, as cells expressing SpAin1(R216E) display disorganized ring material and delays in both ring formation and constriction. Furthermore, computer simulations of initial actin filament elongation and alignment revealed that an intermediate level of cross-linking best facilitates filament alignment. Together our results demonstrate that dynamic bundling by SpAin1 is important for proper contractile ring formation and constriction. PMID:27075176

  12. Vasorelaxant Effect of a Baccharis trimera Infusion on Precontracted Rat Aortic Rings.

    PubMed

    Gómez, Maria A; Migues, Ignacio; Caggiania, Maria; Arias, Ximena; Laprovitera, Mariajose; Blanco, Fabiana; Cesio, Maria Veronica; Migliaro, Eduardo R; Heinzen, Horacio

    2016-03-01

    Baccharis trimera (Less.) DC is a South American plant that in folk medicine is considered to produce reduction in blood pressure. One aspect of this putative effect is the vasorelaxation. The aim of this work was to evaluate the ability of a B. trimera extract to relax rat aortic rings precontracted with noradrenaline. As the infusion is the usual way of intake of this plant, an infusion of B. trimera was prepared using 100 g of the plant (leaves) boiled in water, frozen and lyophilized. Working solutions were prepared using different concentrations of the dried extract diluted in Krebs Henseleit solution. It was proved that the infusion relaxed the aortic rings in a dose dependent manner 100 minutes after adding the exract to the bath. Considering as 100% the maximum contraction achieved with noradrenaline, a relaxation of 101.1 ± 2.3% was observed with the highest dose of the infusion used in these experiments (0.32 mg/mL). While in control rings relaxation was 12.9 ± 2.4%. In aortic rings denuded from endothelium the percentage of vasoralaxation did not show statistically significant differences when compared to intact rings. These data support the hypothesis of a vasorelaxant effect of this plant and constitutes the first approach to the scientific basis of a potential antihypertensive effect. PMID:27169175

  13. Exendin-4 therapy still offered an additional benefit on reducing transverse aortic constriction-induced cardiac hypertrophy-caused myocardial damage in DPP-4 deficient rats.

    PubMed

    Lu, Hung-I; Chung, Sheng-Ying; Chen, Yi-Ling; Huang, Tein-Hung; Zhen, Yen-Yi; Liu, Chu-Feng; Chang, Meng-Wei; Chen, Yung-Lung; Sheu, Jiunn-Jye; Chua, Sarah; Yip, Hon-Kan; Lee, Fan-Yen

    2016-01-01

    Inhibition of dipeptidyl peptidase-IV (DPP-4) enzyme activity has been revealed to protect myocardium from ischemia-reperfusion through enhancing the endogenous glucagon-like peptide-1 (GLP-1) level. However, whether exogenous supply of exendin-4, an analogue of GLP-1, would still offer benefit for protecting myocardial damage from trans-aortic constriction (TAC)-induced hypertrophic cardiomyopathy in preexistence of DPP-4 deficiency (DPP-4(D)) remained unclear. Male-adult (DPP-4(D)) rats (n = 32) were randomized into group 1 [sham control (SC)], group 2 (DPP-4(D) + TAC), group 3 [DPP-4(D) + TAC + exendin-4 10 µg/day], and group 4 [DPP-4(D) + TAC + exendin-4 10 µg + exendin-9-39 10 µg/day]. The rats were sacrificed by day 60 after last echocardiographic examination. By day 60 after TAC, left ventricular ejection fraction (LVEF) (%) was highest in group 1 and lowest in group 2, and significantly lower in group 4 than that in group 3 (all p < 0.001). The protein expressions of oxidative stress (oxidized protein, NOX-1, NOX-2), inflammatory (MMP-9, TNF-α, NF-κB), apoptotic (Bax, cleaved caspase 3 and PARP), fibrotic (TGF-β, Smad3), heart failure (BNP, β-MHC), DNA damaged (γ-H2AX) and ischemic stress (p-P38, p-Akt, p53, ATM) biomarkers showed an opposite pattern of LVEF among the four groups (all p < 0.03). Fibrotic area (by Masson's trichrome, Sirius red), and cellular expressions of DNA-damaged markers (Ki-67+, γ-H2AX+, CD90+/53BP1+) displayed an identical pattern, whereas cellular expressions of angiogenesis (CD31+, α-SMA+) and sarcomere length exhibited an opposite pattern compared to that of oxidative stress among the four groups (all p < 0.001). Take altogether, Exendin-4 effectively suppressed TAC-induced pathological cardiac hypertrophy in DPP-4(D) rat.

  14. A New Animal Model for Investigation of Mechanical Unloading in Hypertrophic and Failing Hearts: Combination of Transverse Aortic Constriction and Heterotopic Heart Transplantation

    PubMed Central

    Stenzig, Justus; Biermann, Daniel; Jelinek, Marisa; Reichenspurner, Hermann; Eschenhagen, Thomas; Ehmke, Heimo; Schwoerer, Alexander P.

    2016-01-01

    Objectives Previous small animal models for simulation of mechanical unloading are solely performed in healthy or infarcted hearts, not representing the pathophysiology of hypertrophic and dilated hearts emerging in heart failure patients. In this article, we present a new and economic small animal model to investigate mechanical unloading in hypertrophic and failing hearts: the combination of transverse aortic constriction (TAC) and heterotopic heart transplantation (hHTx) in rats. Methods To induce cardiac hypertrophy and failure in rat hearts, three-week old rats underwent TAC procedure. Three and six weeks after TAC, hHTx with hypertrophic and failing hearts in Lewis rats was performed to induce mechanical unloading. After 14 days of mechanical unloading animals were euthanatized and grafts were explanted for further investigations. Results 50 TAC procedures were performed with a survival of 92% (46/50). When compared to healthy rats left ventricular surface decreased to 5.8±1.0 mm² (vs. 9.6± 2.4 mm²) (p = 0.001) after three weeks with a fractional shortening (FS) of 23.7± 4.3% vs. 28.2± 1.5% (p = 0.01). Six weeks later, systolic function decreased to 17.1± 3.2% vs. 28.2± 1.5% (p = 0.0001) and left ventricular inner surface increased to 19.9±1.1 mm² (p = 0.0001). Intraoperative graft survival during hHTx was 80% with 46 performed procedures (37/46). All transplanted organs survived two weeks of mechanical unloading. Discussion Combination of TAC and hHTx in rats offers an economic and reproducible small animal model enabling serial examination of mechanical unloading in a truly hypertrophic and failing heart, representing the typical pressure overloaded and dilated LV, occurring in patients with moderate to severe heart failure. PMID:26841021

  15. Endophytic fungal metabolite fumigaclavine C causes relaxation of isolated rat aortic rings.

    PubMed

    Ma, Hsiao-Yen; Song, Yong-Chun; Mao, Ying-Ying; Jiang, Ji-Hong; Tan, Ren-Xiang; Luo, Lan

    2006-04-01

    Two indole alkaloids were isolated from the culture of Aspergillus fumigatus (strain No. CY018), an endophytic fungus harboring inside the elder leaf of Cynodon dactylon. These two chemicals were identified as fumigaclavine C and fumitremorgin C. In screening the bioactivity of these two indole alkaloids, their vasorelaxant effects on isolated rat thoracic aortic rings were observed. The results showed that fumigaclavine C exhibited potent concentration-dependent vasorelaxant actions in isolated rat aortic rings pre-contracted by high K+ or phenylephrine (with EC50 values of 5.62 micromol/L and 1.58 micromol/L, respectively) whereas fumitremorgin C displayed a weaker vasorelaxation. A detailed investigation was therefore performed with fumigaclavine C. The vasorelaxing action of fumigaclavine C is independent of the presence of endothelium, suggesting its effect of vasorelaxation was not related to endothelial mediators. Blockage of L-type voltage-dependent calcium channels, activation of ATP-sensitive potassium channels and inhibition of Ca2+ release from intracellular Ca2+ stores may be involved in fumigaclavine C induced relaxation of rat isolated aortic rings. These results demonstrate that fumigaclavine C from the endophytic fungus has a potential capacity in vascular protection and thus may have therapeutic use in protection against cardiovascular disease. PMID:16557450

  16. First Report of Eurycoma longifolia Jack Root Extract Causing Relaxation of Aortic Rings in Rats

    PubMed Central

    2016-01-01

    Although Eurycoma longifolia has been studied for erectile function, the blood pressure- (BP-) lowering effect has yet to be verified. Hence, this study aims at investigating the BP-lowering properties of the plant with a view to develop an antihypertensive agent that could also preserve erectile function. Ethanolic root extract was partitioned by hexane, dichloromethane (DCM), ethyl acetate, butanol, and water. The DCM fraction, found to be potent in relaxing phenylephrine- (PE-) precontracted rat aortic rings, was further purified by column chromatography. Subfraction DCM-II, being the most active in relaxing aortae, was studied for effects on the renin-angiotensin and kallikrein-kinin systems in aortic rings. The effect of DCM-II on angiotensin-converting enzyme (ACE) activity was also evaluated in vitro. Results showed that DCM-II reduced (p < 0.05) the contractions evoked by angiotensin I and angiotensin II (Ang II). In PE-precontracted rings treated with DCM-II, the Ang II-induced contraction was attenuated (p < 0.05) while bradykinin- (BK-) induced relaxation enhanced (p < 0.001). In vitro, DCM-II inhibited (p < 0.001) the activity of ACE. These data demonstrate that the vasodilatory effect of DCM-II appears to be mediated via inhibition of Ang II type 1 receptor and ACE as well as enhancement of Ang II type 2 receptor activation and BK activity. PMID:27800486

  17. Hydrogen sulfide decreases adenosine triphosphate levels in aortic rings and leads to vasorelaxation via metabolic inhibition

    PubMed Central

    Kiss, Levente; Deitch, Edwin A; Szabó, Csaba

    2014-01-01

    Aims Hydrogen sulfide (H2S) at low concentrations serves as a physiological endogenous vasodilator molecule, while at higher concentrations it can trigger cytotoxic effects. The aim of our study was to elucidate the potential mechanisms responsible for the effects of H2S on vascular tone. Main methods We measured the vascular tone in vitro in precontracted rat thoracic aortic rings and we have tested the effect of different oxygen levels and a variety of inhibitors affecting known vasodilatory pathways. We have also compared the vascular effect of high concentrations of H2S to those of pharmacological inhibitors of oxidative phosphorylation. Furthermore, we measured adenosine triphosphate (ATP)-levels in the same vascular tissues. Key findings We have found that in rat aortic rings: (1) H2S decreases ATP levels; (2) relaxations to H2S depend on the ambient oxygen concentration; (3) prostaglandins do not take part in the H2S induced relaxations; (4) the 3':5'-cyclic guanosine monophosphate (cGMP) – nitric oxide (NO) pathway does not have a role in the relaxations (5) the role of KATP channels is limited, while Cl−/HCO3− channels have a role in the relaxations. (6): We have observed that high concentrations of H2S relax the aortic rings in a fashion similar to sodium cyanide, and both agents reduce cellular ATP levels to a comparable degree. Significance H2S, a new gasotransmitter of emerging importance, leads to relaxation via Cl−/HCO3− channels and metabolic inhibition and the interactions of these two factors depend on the oxygen levels of the tissue. PMID:18790700

  18. Vascular Response of Ruthenium Tetraamines in Aortic Ring from Normotensive Rats

    PubMed Central

    Conceição-Vertamatti, Ana Gabriela; Ramos, Luiz Alberto Ferreira; Calandreli, Ivy; Chiba, Aline Nunes; Franco, Douglas Wagner; Tfouni, Elia; Grassi-Kassisse, Dora Maria

    2015-01-01

    Background Ruthenium (Ru) tetraamines are being increasingly used as nitric oxide (NO) carriers. In this context, pharmacological studies have become highly relevant to better understand the mechanism of action involved. Objective To evaluate the vascular response of the tetraamines trans-[RuII(NH3)4(Py)(NO)]3+, trans-[RuII(Cl)(NO) (cyclan)](PF6)2, and trans-[RuII(NH3)4(4-acPy)(NO)]3+. Methods Aortic rings were contracted with noradrenaline (10−6 M). After voltage stabilization, a single concentration (10−6 M) of the compounds was added to the assay medium. The responses were recorded during 120 min. Vascular integrity was assessed functionally using acetylcholine at 10−6 M and sodium nitroprusside at 10−6 M as well as by histological examination. Results Histological analysis confirmed the presence or absence of endothelial cells in those tissues. All tetraamine complexes altered the contractile response induced by norepinephrine, resulting in increased tone followed by relaxation. In rings with endothelium, the inhibition of endothelial NO caused a reduction of the contractile effect caused by pyridine NO. No significant responses were observed in rings with endothelium after treatment with cyclan NO. In contrast, in rings without endothelium, the inhibition of guanylate cyclase significantly reduced the contractile response caused by the pyridine NO and cyclan NO complexes, and both complexes caused a relaxing effect. Conclusion The results indicate that the vascular effect of the evaluated complexes involved a decrease in the vascular tone induced by norepinephrine (10−6 M) at the end of the incubation period in aortic rings with and without endothelium, indicating the slow release of NO from these complexes and suggesting that the ligands promoted chemical stability to the molecule. Moreover, we demonstrated that the association of Ru with NO is more stable when the ligands pyridine and cyclan are used in the formulation of the compound. PMID

  19. Erythropoietin has an antiapoptotic effect after myocardial infarction and stimulates in vitro aortic ring sprouting

    SciTech Connect

    Mansson Broberg, Agneta; Grinnemo, Karl-Henrik; Genead, Rami; Danielsson, Christian; Andersson, Agneta B.; Waerdell, Eva; Sylven, Christer

    2008-06-20

    Aims were to explore if darbepoietin-{alpha} in mouse can induce angiogenesis and if moderate doses after myocardial infarction stimulates periinfarct capillary and arteriolar densities, cell proliferation, and apoptosis. Myocardial infarction was induced by ligation of LAD. Mouse aortic rings (0.8 mm) were cultured in matrigel and the angiogenic sprouting was studied after addition of darbepoietin-{alpha} with and without VEGF-165. After 12 days the hemoglobin concentration was 25% higher in the darbepoietin-{alpha} treated mice than in the control group. No difference in capillary densities in the periinfarct or noninfarcted areas was seen with darbepoietin-{alpha}. Cell proliferation was about 10 times higher in the periinfarct area than in the noninfarcted wall. Darbepoietin-{alpha} treatment led to a decrease of cell proliferation (BrdU, (p < 0.02)) and apoptosis (TUNEL, p < 0.005) with about 30% in the periinfarct area. Darbepoietin-{alpha} and VEGF-165 both independently induced sprouting from aortic rings. The results suggest that darbepoietin-{alpha} can induce angiogenesis but that moderate doses after myocardial infarction are not angiogenic but antiapoptotic.

  20. BAY K 8644-induced enhancement of 45Ca uptake by rabbit aortic rings

    SciTech Connect

    Scriabine, A.; Anderson, C.L.; Janis, R.A.

    1986-07-01

    BAY K 8644, a Ca/sup 2 +/ channel activator, enhances uptake of /sup 45/Ca by rabbit aortic rings. This effect depends on the concentration of K/sup +/ in the medium: at 20 mM K/sup +/ the effect of BAY K 8644 was more pronounced than at 5 mM, whereas at 80 mM, no significant enhancement of /sup 45/Ca uptake by BAY K 8644 was found. In the medium containing 5 mM K/sup +/, BAY K 8644 was effective in experiments involving 10 or 30 (but not 3) min exposure of aortic rings to /sup 45/Ca. The dose-response curve for BAY K 8644 was established in 5 mM K/sup +/-containing medium and for 30 min exposure to /sup 45/Ca. BAY K 8644 was effective at 0.01 microM and higher concentrations. In the presence of norepinephrine (0.1 or 10 microM), BAY K 8644 had no greater effect on /sup 45/Ca uptake than in control 5 mM K/sup +/ medium. Our observation that the presence of norepinephrine in 5 mM K/sup +/ did not enhance BAY K 8644-induced /sup 45/Ca uptake suggests that activation of alpha-adrenergic receptor does not depolarize aortic membranes to the same extent as an increase in K+ concentration to 20 mM or that BAY K 8644 does not enhance Ca/sup 2 +/ entry through receptor-operated channels.

  1. Peroxynitrite-induced relaxation in isolated rat aortic rings and mechanisms of action

    SciTech Connect

    Li Jianfeng; Li Wenyan; Altura, Bella T.; Altura, Burton M. . E-mail: baltura@downstate.edu

    2005-12-15

    The present study was designed to evaluate the effects of peroxynitrite (ONOO{sup -}), the product of superoxide and nitric oxide, on isolated segments of rat aorta. In the absence of any vasoactive agent, ONOO{sup -} (from 10{sup -8} to 10{sup -4} M) failed to alter the basal tension. In phenylephrine (PE; 5 x 10{sup -7} M)-precontracted rat aortic rings (RAR), ONOO{sup -} elicited concentration-dependent relaxation at concentrations of from 10{sup -8} to 10{sup -4} M. The effective concentrations producing approximately 50% of maximal relaxation (ED{sub 5}) to ONOO{sup -} were 1.84 x 10{sup -5} M and 1.96 x 10{sup -5} M in intact and denuded RAR, respectively (P > 0.05). No significant differences in the relaxation responses were found between RAR with or without endothelium (P > 0.05). The presence of either 5 {mu}M methylene blue (MB) or 5 {mu}M 1H-[1,2,4]oxadiazolo-[4,3-{alpha}]quinoxalin-1-one (ODQ) significantly inhibited the relaxations induced by ONOO{sup -}. Sildenafil (10{sup -7} M), on the other hand, significantly potentiated the ONOO{sup -}-induced relaxations. Tetraethylammonium chloride (T-2265) significantly decreased the ONOO{sup -}-induced relaxations in a concentration-dependent manner. However, ONOO{sup -} had no effect on RAR precontracted by high KCL (40 mM, n = 6, P > 0.05). Addition of calyculin A also significantly decreased the ONOO{sup -}-induced relaxation in a dose-dependent manner. Furthermore, ONOO{sup -} significantly inhibited calcium-induced contractions of K{sup +}-depolarized aortic rings in a concentration-related manner. Lastly, a variety of other pharmacological agents and antagonists including L-NMMA, L-arginine, indomethacin, atropine, naloxone, diphenhydramine, cimetine, glibenclamide, haloperidol, superoxide dismutase (SOD), and catalase did not influence the relaxant effects of ONOO{sup -} on RAR. Our new results suggest that ONOO{sup -}-triggered relaxation on rat aortic rings is mediated by elevation of cGMP levels

  2. Mechanisms involved in the vasorelaxant effects produced by the acute application of amfepramone in vitro to rat aortic rings

    PubMed Central

    López-Canales, J.S.; Lozano-Cuenca, J.; Muãoz-Islas, E.; Aguilar-Carrasco, J.C.; López-Canales, O.A.; López-Mayorga, R.M.; Castillo-Henkel, E.F.; Valencia-Hernández, I.; Castillo-Henkel, C.

    2015-01-01

    Amfepramone (diethylpropion) is an appetite-suppressant drug used for the treatment of overweight and obesity. It has been suggested that the systemic and central activity of amfepramone produces cardiovascular effects such as transient ischemic attacks and primary pulmonary hypertension. However, it is not known whether amfepramone produces immediate vascular effects when applied in vitro to rat aortic rings and, if so, what mechanisms may be involved. We analyzed the effect of amfepramone on phenylephrine-precontracted rat aortic rings with or without endothelium and the influence of inhibitors or blockers on this effect. Amfepramone produced a concentration-dependent vasorelaxation in phenylephrine-precontracted rat aortic rings that was not affected by the vehicle, atropine, 4-AP, glibenclamide, indomethacin, clotrimazole, or cycloheximide. The vasorelaxant effect of amfepramone was significantly attenuated by NG-nitro-L-arginine methyl ester (L-NAME) and tetraethylammonium (TEA), and was blocked by removal of the vascular endothelium. These results suggest that amfepramone had a direct vasorelaxant effect on phenylephrine-precontracted rat aortic rings, and that inhibition of endothelial nitric oxide synthase and the opening of Ca2+-activated K+ channels were involved in this effect. PMID:25831200

  3. Proper Actin Ring Formation and Septum Constriction Requires Coordinated Regulation of SIN and MOR Pathways through the Germinal Centre Kinase MST-1

    PubMed Central

    Heilig, Yvonne; Dettmann, Anne; Mouriño-Pérez, Rosa R.; Schmitt, Kerstin; Valerius, Oliver; Seiler, Stephan

    2014-01-01

    Nuclear DBF2p-related (NDR) kinases constitute a functionally conserved protein family of eukaryotic regulators that control cell division and polarity. In fungi, they function as effector kinases of the morphogenesis (MOR) and septation initiation (SIN) networks and are activated by pathway-specific germinal centre (GC) kinases. We characterized a third GC kinase, MST-1, that connects both kinase cascades. Genetic and biochemical interactions with SIN components and life cell imaging identify MST-1 as SIN-associated kinase that functions in parallel with the GC kinase SID-1 to activate the SIN-effector kinase DBF-2. SID-1 and MST-1 are both regulated by the upstream SIN kinase CDC-7, yet in an opposite manner. Aberrant cortical actomyosin rings are formed in Δmst-1, which resulted in mis-positioned septa and irregular spirals, indicating that MST-1-dependent regulation of the SIN is required for proper formation and constriction of the septal actomyosin ring. However, MST-1 also interacts with several components of the MOR network and modulates MOR activity at multiple levels. MST-1 functions as promiscuous enzyme and also activates the MOR effector kinase COT-1 through hydrophobic motif phosphorylation. In addition, MST-1 physically interacts with the MOR kinase POD-6, and dimerization of both proteins inactivates the GC kinase hetero-complex. These data specify an antagonistic relationship between the SIN and MOR during septum formation in the filamentous ascomycete model Neurospora crassa that is, at least in part, coordinated through the GC kinase MST-1. The similarity of the SIN and MOR pathways to the animal Hippo and Ndr pathways, respectively, suggests that intensive cross-communication between distinct NDR kinase modules may also be relevant for the homologous NDR kinases of higher eukaryotes. PMID:24762679

  4. Brazilin isolated from the heartwood of Caesalpinia sappan L induces endothelium-dependent and -independent relaxation of rat aortic rings

    PubMed Central

    Yan, Yu; Chen, Yu-cai; Lin, Yi-huang; Guo, Jing; Niu, Zi-ran; Li, Li; Wang, Shou-bao; Fang, Lian-hua; Du, Guan-hua

    2015-01-01

    Aim: Brazilin is one of the major constituents of Caesalpinia sappan L with various biological activities. This study sought to investigate the vasorelaxant effect of brazilin on isolated rat thoracic aorta and explore the underlying mechanisms. Methods: Endothelium-intact and -denuded aortic rings were prepared from rats. The tension of the preparations was recorded isometrically with a force displacement transducer connected to a polygraph. The phosphorylation levels of ERK1/2 and myosin light chain (MLC) were analyzed using Western blotting assay. Results: Application of brazilin (10–100 μmol/L) dose-dependently relaxed the NE- or high K+-induced sustained contraction of endothelium-intact aortic rings (the EC50 was 83.51±5.6 and 79.79±4.57 μmol/L, respectively). The vasorelaxant effect of brazilin was significantly attenuated by endothelium removal or by pre-incubation with L-NAME, methylene blue or indomethacin. In addition, pre-incubation with brazilin dose-dependently attenuated the vasoconstriction induced by KCl, NE or Ang II. Pre-incubation with brazilin also markedly suppressed the high K+-induced extracellular Ca2+ influx and NE-induced intracellular Ca2+ release in endothelium-denuded aortic rings. Pre-incubation with brazilin dose-dependently inhibited the NE-stimulated phosphorylation of ERK1/2 and MLC in both endothelium-intact and -denuded aortic rings. Conclusion: Brazilin induces relaxation in rat aortic rings via both endothelium-dependent and -independent ways as well as inhibiting NE-stimulated phosphorylation of ERK1/2 and MLC. Brazilin also attenuates vasoconstriction via blocking voltage- and receptor-operated Ca2+ channels. PMID:26564314

  5. Video assisted thoracoscopic surgery cases with right-sided aortic arch aneurysm and complete vascular ring: Case report

    PubMed Central

    Nezafati, Mohammad Hassan; Nezafati, Pouya

    2014-01-01

    Introduction Right-sided aortic arch with aberrant left subclavian artery and ligamentum arteriosum, after double aortic arch, is the second most common complete vascular ring. It was traditionally treated by open surgical thoracotomy and recently video assisted thoracoscopic surgery (VATS) has been used in some cases. Presentation of case We describe the cases of two infants who presented with gastroesophageal reflux, dyspnea, dysphagia secondary to aneurysmal dilatation of the retroesophageal arch confirmed by imaging data. VATS procedure was performed through a left thoracoscopic approach. Ligamentum arteriosus compressed esophagus was clipped, sectioned and then released the esophagus in one case; also, In the second case, we clipped and sectioned aorta, distal to the origin of aberrant left subclavian artery. Discussion CT angiography and MRI are known to be the most effective available imaging methods for vascular ring detection. Also, there are several surgical approaches to vascular rings such as, thoracotomy and thoracoscopy. There is a large body of evidence confirming the safety, efficacy and convenience of VATS as a therapeutic option for congenital heart disease including right-sided aortic arch and aberrant left subclavian artery. Conclusion VATS is a less invasive and safe strategy for management of right-sided aortic arch with aberrant left subclavian artery and ligamentum arteriosum. PMID:25544489

  6. Role of insulin preincubation in the contractile reactivity of rat aortic rings.

    PubMed

    Rebolledo, A; Milesi, V; Alvis, A G; Rinaldi, G J; Grassi de Gende, A O

    1998-12-01

    Preincubation with physiological concentrations of insulin affects contractile reactivity of isolated smooth muscle cells. We studied the effects of insulin on intact aortic rings of Wistar rats preincubated 1-2 h with 240 pM (I1) and 960 pM (I2) insulin with and without NO synthesis inhibition by N(omega)-nitro-L-arginine methyl ester (L-NAME). Resting force was tripled by 0.1 mM L-NAME in control (C) and I1 groups, but not in I2 groups. I1 treatment decreased the tachyphylaxis to two successive 1 microM arginine vasopressin (AVP) stimulations. Single contractions elicited by 1 microM AVP, 1 microM angiotensin II (AngII), or 0.01 microM endothelin (ET1) were not affected by insulin preincubation in either maximal force (Fmax) or relaxation times. L-NAME enhanced Fmax of AngII contractions by about 75% in C, 120% in I1, and 74% in I2 groups; accordingly, it augmented the final steady-state force in C and I1 but not in I2. Similarly, L-NAME increased Fmax (30-40%) of AVP and ET1 contractions in C and I1 groups but failed to do so in contractions of I2 group. Results obtained with 10 microM indomethacin suggest that this is due to insulin stimulation of prostacyclin effects. PMID:10326827

  7. Single-walled carbon nanotubes (SWCNTs) induce vasodilation in isolated rat aortic rings.

    PubMed

    Gutiérrez-Hernández, J M; Ramirez-Lee, M A; Rosas-Hernandez, H; Salazar-García, S; Maldonado-Ortega, D A; González, F J; Gonzalez, C

    2015-06-01

    Single-walled carbon nanotubes (SWCNTs) are used in biological systems with impact in biomedicine in order to improve diagnostics and treatment of diseases. However, their effects upon the vascular system, are not fully understood. Endothelium and smooth muscle cells (SMC) communicate through release of vasoactive factors as nitric oxide (NO) to maintain vascular tone. The aim of this study was to evaluate the effect of SWCNTs on vascular tone using isolated rat aortic rings, which were exposed to SWCNTs (0.1, 1 and 10 μg/mL) in presence and absence of endothelium. SWCNTs induced vasodilation in both conditions, indicating that this effect was independent on endothelium; moreover that vasodilation was NO-independent, since its blockage with L-NAME did not modify the observed effect. Together, these results indicate that SWCNTs induce vasodilation in the macrovasculature, may be through a direct interaction with SMC rather than endothelium independent of NO production. Further investigation is required to fully understand the mechanisms of action and mediators involved in the signaling pathway induced by SWCNTs on the vascular system.

  8. Tetramethylpyrazine Protects against Hydrogen Peroxide-Provoked Endothelial Dysfunction in Isolated Rat Aortic Rings: Implications for Antioxidant Therapy of Vascular Diseases.

    PubMed

    Ni, Xiaojia; Wong, Siu Ling; Wong, Chi Ming; Lau, Chi Wai; Shi, Xiaogeng; Cai, Yefeng; Huang, Yu

    2014-01-01

    Background and Objectives. Oxidative stress can initiate endothelial dysfunction and atherosclerosis. This study evaluated whether tetramethylpyrazine (TMP), the predominant active ingredient in Rhizoma Ligustici Wallichii (chuanxiong), prevents endothelial dysfunction in a rat model of oxidative stress. Methods. Isolated rat aortic rings were pretreated with various drugs before the induction of endothelial dysfunction by hydrogen peroxide (H2O2). Changes in isometric tension were then measured in acetylcholine- (ACh-) relaxed rings. Endothelial nitric oxide synthase (eNOS) expression was evaluated in the rings by Western blotting, and superoxide anion (O2 (∙-)) content was assessed in primary rat aortic endothelial cells by dihydroethidium- (DHE-) mediated fluorescence microscopy. Results. ACh-induced endothelium-dependent relaxation (EDR) was disrupted by H2O2 in endothelium-intact aortic rings. H2O2-impaired relaxation was ameliorated by acute pretreatment with low concentrations of TMP, as well as by pretreatment with catalase and the NADPH oxidase inhibitors, apocynin and diphenyleneiodonium (DPI). TMP, apocynin, and DPI also reduced O2 (∙-) accumulation in endothelial cells,but TMP failed to alter eNOS expression in aortic rings incubated with H2O2. Conclusions. TMP safeguards against oxidative stress-induced endothelial dysfunction, suggesting that the agent might find therapeutic utility in the management of vascular diseases. However, TMP's role in inhibiting NADPH oxidase and its vascular-protective mechanism of action requires further investigation. PMID:25258643

  9. Pharmacological characterization of mechanisms involved in the vasorelaxation produced by rosuvastatin in aortic rings from rats with a cafeteria-style diet

    PubMed Central

    López-Canales, Jorge Skiold; Lozano-Cuenca, Jair; López-Canales, Oscar Alberto; Aguilar-Carrasco, José Carlos; Aranda-Zepeda, Lidia; López-Sánchez, Pedro; Castillo-Henkel, Enrique Fernando; López-Mayorga, Ruth Mery; Valencia-Hernández, Ignacio

    2015-01-01

    The present study aimed to investigate the possible influence of several inhibitors and blockers on the vascular effect produced by the acute in vitro application of rosuvastatin to phenylephrine-precontracted aortic rings from rats with a semi-solid, cafeteria-style (CAF) diet. It also aimed to examine the effects of rosuvastatin on the expression of endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase, constitutive cyclooxygenase, and inducible cyclooxygenase in aortic rings from rats with a CAF diet. From comparisons of the effect on phenylephrine-precontracted aortic rings extracted from rats with two different diets (a standard and a CAF diet), it was found that 10−9–10−5-mol/L rosuvastatin produced lower concentration-dependent vasorelaxation on rings from the CAF diet group. The vasorelaxant effect was unaffected by the vehicle, but it was significantly attenuated by 10−5-mol/L NG-nitro-l-arginine methyl ester, 10−2-mol/L tetraethylammonium, 10−3-mol/L 4-aminopyridine, 10−7-mol/L apamin plus 10−7-mol/L charybdotoxin, 10−5-mol/L indomethacin, or 10−5-mol/L cycloheximide. Moreover, in aortic rings from rats with a CAF diet, rosuvastatin enhanced the expression of eNOS, inducible nitric oxide synthase, constitutive cyclooxygenase, and inducible cyclooxygenase. The acute in vitro application of rosuvastatin to phenylephrine-precontracted aortic rings from rats with a CAF diet had a vasorelaxant effect. Overall, the present results suggest that the stimulation of eNOS, the opening of Ca2+-activated and voltage-activated K+ channels, the stimulation of prostaglandin synthesis and enhanced protein levels of eNOS, inducible nitric oxide synthase, constitutive cyclooxygenase, and inducible cyclooxygenase are involved in this relaxant effect. PMID:25881486

  10. Long-term effect of bilateral ovariectomy on endothelial function in aortic rings of spontaneously hypertensive rats: role of nitric oxide.

    PubMed

    Riveiro, A; Mosquera, A; Calvo, C; Alonso, M; Macía, M; Cores, M

    2001-04-01

    Endothelial dysfunction associated with both menopause and hypertension could be one of the possible explanations for increased cardiovascular morbidity and mortality in hypertensive postmenopausal women. The aim of the present study was to investigate the long-term effect of menopause (bilateral ovariectomy) on endothelial function in isolated aortic rings of spontaneously hypertensive rats (SHR). Aortic rings were suspended in organ chambers filled with physiological salt solution (95% O2, 5% CO2, 37 degrees C), and isometric tension was measured. In studies designed to assess the tone-related release of nitric oxide (NO) from phenylephrine-precontracted aortic rings, we found that vasoconstriction induced by L-NAME was greater in aortic rings from sham-ovariectomized SHR (SHAM SHR) than in those obtained from ovariectomized SHR (OVX SHR). Concentration-related relaxant responses to superoxide dismutase were significantly greater in the SHAM SHR than in the OVX SHR. In contrast, receptor-mediated release of NO was not altered by ovariectomy, as deduced from acetylcholine (ACh) concentration-responses curves. Responses to the exogenous NO donor sodium nitroprusside (SNP) were also identical in both ovariectomized and sham-ovariectomized groups, ruling out differences in smooth muscle reactivity to NO. These results show that NO release is impaired in OVX SHR, an animal model of simultaneous hypertension and menopause.

  11. Actin Rings of Power.

    PubMed

    Schwayer, Cornelia; Sikora, Mateusz; Slováková, Jana; Kardos, Roland; Heisenberg, Carl-Philipp

    2016-06-20

    Circular or ring-like actin structures play important roles in various developmental and physiological processes. Commonly, these rings are composed of actin filaments and myosin motors (actomyosin) that, upon activation, trigger ring constriction. Actomyosin ring constriction, in turn, has been implicated in key cellular processes ranging from cytokinesis to wound closure. Non-constricting actin ring-like structures also form at cell-cell contacts, where they exert a stabilizing function. Here, we review recent studies on the formation and function of actin ring-like structures in various morphogenetic processes, shedding light on how those different rings have been adapted to fulfill their specific roles. PMID:27326928

  12. Electrophysiology of Axonal Constrictions

    NASA Astrophysics Data System (ADS)

    Johnson, Christopher; Jung, Peter; Brown, Anthony

    2013-03-01

    Axons of myelinated neurons are constricted at the nodes of Ranvier, where they are directly exposed to the extracellular space and where the vast majority of the ion channels are located. These constrictions are generated by local regulation of the kinetics of neurofilaments the most important cytoskeletal elements of the axon. In this paper we discuss how this shape affects the electrophysiological function of the neuron. Specifically, although the nodes are short (about 1 μm) in comparison to the distance between nodes (hundreds of μm) they have a substantial influence on the conduction velocity of neurons. We show through computational modeling that nodal constrictions (all other features such as numbers of ion channels left constant) reduce the required fiber diameter for a given target conduction velocity by up to 50% in comparison to an unconstricted axon. We further show that the predicted optimal fiber morphologies closely match reported fiber morphologies. Supported by The National Science Foundation (IOS 1146789)

  13. Multi-Detector Row Computed Tomographic Evaluation of a Rare Type of Complete Vascular Ring: Double Aortic Arch with Atretic Left Arch Distal to the Origin of Left Subclavian Artery

    PubMed Central

    Hung, Ying-Ying; Fu, Yun-Ching; Wei, Hao-Ji; Chen, Clayton Chi-Chang

    2013-01-01

    Double aortic arch with an atretic left arch distal to the origin of left subclavian artery was diagnosed with multi-detector row computed tomography (MDCT) in two children with dysphagia. This rare type of complete vascular ring is clinically important because it may be confused with right aortic arch in mirror imaging. Anatomic details of this rare type of complete vascular ring demonstrated on MDCT facilitated appropriate surgical treatment. PMID:24043984

  14. Pharmacological study of the mechanisms involved in the vasodilator effect produced by the acute application of triiodothyronine to rat aortic rings

    PubMed Central

    Lozano-Cuenca, J.; López-Canales, O.A.; Aguilar-Carrasco, J.C.; Villagrana-Zesati, J.R.; López-Mayorga, R.M.; Castillo-Henkel, E.F.; López-Canales, J.S.

    2016-01-01

    A relationship between thyroid hormones and the cardiovascular system has been well established in the literature. The present in vitro study aimed to investigate the mechanisms involved in the vasodilator effect produced by the acute application of 10-8–10-4 M triiodothyronine (T3) to isolated rat aortic rings. Thoracic aortic rings from 80 adult male Wistar rats were isolated and mounted in tissue chambers filled with Krebs-Henseleit bicarbonate buffer in order to analyze the influence of endothelial tissue, inhibitors and blockers on the vascular effect produced by T3. T3 induced a vasorelaxant response in phenylephrine-precontracted rat aortic rings at higher concentrations (10-4.5–10-4.0 M). This outcome was unaffected by 3.1×10-7 M glibenclamide, 10-3 M 4-aminopyridine (4-AP), 10-5 M indomethacin, or 10-5 M cycloheximide. Contrarily, vasorelaxant responses to T3 were significantly (P<0.05) attenuated by endothelium removal or the application of 10-6 M atropine, 10-5 M L-NG-nitroarginine methyl ester (L-NAME), 10-7 M 1H-(1,2,4)oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), 10-6 M (9S,10R,12R)-2,3,9,10,11,12-Hexahydro-10-methoxy-2,9-dimethyl-1-oxo-9,12-epoxy-1H-diindolo[1,2,3-fg:3′,2′,1′-kl]pyrrolo[3,4-i](1,6)benzodiazocine-10-carboxylic acid, methyl ester KT 5823, 10-2 M tetraethylammonium (TEA), or 10-7 M apamin plus 10-7 M charybdotoxin. The results suggest the involvement of endothelial mechanisms in the vasodilator effect produced by the acute in vitro application of T3 to rat aortic rings. Possible mechanisms include the stimulation of muscarinic receptors, activation of the NO-cGMP-PKG pathway, and opening of Ca2+-activated K+ channels. PMID:27464023

  15. Pharmacological study of the mechanisms involved in the vasodilator effect produced by the acute application of triiodothyronine to rat aortic rings.

    PubMed

    Lozano-Cuenca, J; López-Canales, O A; Aguilar-Carrasco, J C; Villagrana-Zesati, J R; López-Mayorga, R M; Castillo-Henkel, E F; López-Canales, J S

    2016-07-25

    A relationship between thyroid hormones and the cardiovascular system has been well established in the literature. The present in vitro study aimed to investigate the mechanisms involved in the vasodilator effect produced by the acute application of 10-8-10-4 M triiodothyronine (T3) to isolated rat aortic rings. Thoracic aortic rings from 80 adult male Wistar rats were isolated and mounted in tissue chambers filled with Krebs-Henseleit bicarbonate buffer in order to analyze the influence of endothelial tissue, inhibitors and blockers on the vascular effect produced by T3. T3 induced a vasorelaxant response in phenylephrine-precontracted rat aortic rings at higher concentrations (10-4.5-10-4.0 M). This outcome was unaffected by 3.1×10-7 M glibenclamide, 10-3 M 4-aminopyridine (4-AP), 10-5 M indomethacin, or 10-5 M cycloheximide. Contrarily, vasorelaxant responses to T3 were significantly (P<0.05) attenuated by endothelium removal or the application of 10-6 M atropine, 10-5 M L-NG-nitroarginine methyl ester (L-NAME), 10-7 M 1H-(1,2,4)oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), 10-6 M (9S,10R,12R)-2,3,9,10,11,12-Hexahydro-10-methoxy-2,9-dimethyl-1-oxo-9,12-epoxy-1H-diindolo[1,2,3-fg:3',2',1'-kl]pyrrolo[3,4-i](1,6)benzodiazocine-10-carboxylic acid, methyl ester KT 5823, 10-2 M tetraethylammonium (TEA), or 10-7 M apamin plus 10-7 M charybdotoxin. The results suggest the involvement of endothelial mechanisms in the vasodilator effect produced by the acute in vitro application of T3 to rat aortic rings. Possible mechanisms include the stimulation of muscarinic receptors, activation of the NO-cGMP-PKG pathway, and opening of Ca2+-activated K+ channels. PMID:27464023

  16. Vasorelaxant Effect of a New Hydrogen Sulfide-Nitric Oxide Conjugated Donor in Isolated Rat Aortic Rings through cGMP Pathway

    PubMed Central

    Wu, Dan; Hu, Qingxun; Ma, Fenfen; Zhu, Yi Zhun

    2016-01-01

    Endothelium-dependent vasorelaxant injury leads to a lot of cardiovascular diseases. Both hydrogen sulfide (H2S) and nitric oxide (NO) are gasotransmitters, which play a critical role in regulating vascular tone. However, the interaction between H2S and NO in vasorelaxation is still unclear. ZYZ-803 was a novel H2S and NO conjugated donor developed by H2S-releasing moiety (S-propyl-L-cysteine (SPRC)) and NO-releasing moiety (furoxan). ZYZ-803 could time- and dose-dependently relax the sustained contraction induced by PE in rat aortic rings, with potencies of 1.5- to 100-fold greater than that of furoxan and SPRC. Inhibition of the generations of H2S and NO with respective inhibitors abolished the vasorelaxant effect of ZYZ-803. ZYZ-803 increased cGMP level and the activity of vasodilator stimulated phosphoprotein (VASP) in aortic rings, and those effects could be suppressed by the inhibitory generation of H2S and NO. Both the inhibitor of protein kinase G (KT5823) and the inhibitor of KATP channel (glibenclamide) suppressed the vasorelaxant effect of ZYZ-803. Our results demonstrated that H2S and NO generation from ZYZ-803 cooperatively regulated vascular tone through cGMP pathway, which indicated that ZYZ-803 had therapeutic potential in cardiovascular diseases. PMID:26635911

  17. Occupational causes of constrictive bronchiolitis

    PubMed Central

    Kreiss, Kathleen

    2015-01-01

    Purpose of review New literature from 2009 to 2012 regarding occupational constrictive bronchiolitis challenges textbook descriptions of this disease, formerly thought to be limited to fixed airflow limitation arising in the wake of accidental overexposure to noxious chemicals. Indolent evolution of dyspnea without a recognized hazardous exposure is a more common presentation. Recent findings Biopsy-confirmed case series of constrictive bronchiolitis from US soldiers, Iranian survivors of sulfur mustard gassing, hospital-based studies, and flavoring-related cases document that indolent constrictive bronchiolitis cases can have normal spirometry or either restrictive or obstructive abnormalities. High-resolution computerized tomography studies can be normal or reflect air-trapping and mosaic attenuation on expiratory films. Thus, in the absence of noninvasive abnormalities, the diagnosis in dyspneic patients may require thoracoscopic biopsy in settings in which exposure risk has not been recognized. Many workers with occupational constrictive bronchiolitis stabilize with cessation of exposures causing bronchiolar epithelial necrosis. Summary Clinicians need a high index of suspicion for constrictive bronchiolitis in young patients with rapidly progressing exertional dyspnea, regardless of spirometric and radiologic findings. Identification of novel causes and exposure-response relations for known causes are needed to provide guidance for protecting workers at risk for this largely irreversible lung disease. PMID:23407121

  18. Aetiology of chronic constrictive pericarditis.

    PubMed Central

    Blake, S; Bonar, S; O'Neill, H; Hanly, P; Drury, I; Flanagan, M; Garrett, J

    1983-01-01

    In a consecutive series of 32 cases of chronic constrictive pericarditis treated by pericardiectomy during the past 25 years, four were attributable to rheumatoid disease, two to trauma, one to sarcoidosis, and four, at a maximum, to tuberculosis. In the remaining 21 cases of undetermined aetiology there was no evidence of tuberculosis. It appears, therefore, that tuberculosis was not a common cause of chronic constrictive pericarditis during the period under review, which included the 1950s and early 1960s when tuberculosis was widespread. PMID:6615663

  19. Constricted glow discharge plasma source

    DOEpatents

    Anders, Andre; Anders, Simone; Dickinson, Michael; Rubin, Michael; Newman, Nathan

    2000-01-01

    A constricted glow discharge chamber and method are disclosed. The polarity and geometry of the constricted glow discharge plasma source is set so that the contamination and energy of the ions discharged from the source are minimized. The several sources can be mounted in parallel and in series to provide a sustained ultra low source of ions in a plasma with contamination below practical detection limits. The source is suitable for applying films of nitrides such as gallium nitride and oxides such as tungsten oxide and for enriching other substances in material surfaces such as oxygen and water vapor, which are difficult process as plasma in any known devices and methods. The source can also be used to assist the deposition of films such as metal films by providing low-energy ions such as argon ions.

  20. Study of the effect of thiols on the vasodilatory potency of S-nitrosothiols by using a modified aortic ring assay

    SciTech Connect

    Giustarini, Daniela; Tsikas, Dimitrios; Rossi, Ranieri

    2011-10-15

    Both low-molecular-mass thiols (LMM-SH) and protein thiols (P-SH) can modulate the biological activity of S-nitrosothiols (RSNO) via S-transnitrosation reactions. It has been difficult to evaluate the entity of this effect in blood circulation by in vitro assays with isolated aorta rings so far, because media rich in proteins cannot be used due to the foaming as a consequence of the needed gas bubbling. We have modified the original apparatus for organ bioassay in order to minimize foaming and to increase analytical performance. By using this modified bioassay we investigated the vasodilatory potency of various endogenous RSNOs in the presence of physiologically relevant concentrations of albumin and LMM-SH. Our results show that the sulfhydryl group of the cysteine moiety of albumin and LMM-SH has a dramatic effect on the vasodilatory potency of RSNO. Considering the equilibrium constants for S-transnitrosation reactions and the concentration of P-SH and LMM-SH we measured in healthy humans (aged 18-85 years), we infer that the age-dependency of hematic levels of LMM-SH may have a considerable impact in RSNO-mediated vasodilation. S-Nitrosoproteins such as S-nitrosoalbumin may constitute a relatively silent and constant amount of circulating RSNO. On the other hand, LMM-SH may mediate and control the biological actions of S-nitrosoproteins via S-transnitrosation reactions, by forming more potent nitric oxide-releasing LMM-S-nitrosothiols. Lifestyle habits, status of health and individual age are proven factors that, in turn, may influence the concentration of these compounds. These aspects should be taken into consideration when testing the vasodilatory effects of RSNO in pre-clinical studies. - Highlights: > A modification of the organ chamber apparatus for aortic ring bioassays is proposed. > The new apparatus can work in the presence of albumin at physiological concentrations. > Potency of RSNOs was studied in the presence of albumin and low molecular mass -SH

  1. MR imaging evaluation of pericardial constriction.

    PubMed

    Groves, Robert; Chan, Danielle; Zagurovskaya, Marianna; Teague, Shawn D

    2015-02-01

    Abnormal thickening or rigidity of the pericardium may compromise normal cardiac function. This condition is known as pericardial constriction, or constrictive pericarditis. Several imaging modalities are used to evaluate the pericardium, including MR, computed tomography, and echocardiography, which can all play a complementary role aiding diagnosis. This article focuses on MR imaging and its role in the detection and evaluation of pericardial constriction. MR imaging has many advantages compared with other modalities including precise delineation of the pericardial thickness, evaluation of ventricular function, detection of wall motion abnormalities, and provision of information about common (and potentially harmful) sequelae of pericardial constriction. PMID:25476676

  2. Constrictive Pericarditis Long after a Gunshot Wound

    PubMed Central

    Choi, Jung-Ho; Uhm, Jae-Sun; Lee, Sang-Eun; Chun, Kyung-Hyeon; Lee, Hye-Jeong; Lee, Seung Hyun; Hong, Geu-Ru

    2015-01-01

    Constrictive pericarditis is an uncommon post-inflammatory disorder characterized by a variably thickened, fibrotic, and frequently calcified, pericardium. Etiology of the constriction can occur for many reasons. Although foreign bodies are not the common cause of constrictive pericarditis, the long-term presence of foreign bodies, like bullets, is presumed to cause chronic constrictive pericarditis even after a very long asymptomatic period. A 69-year-old patient with atrial flutter was admitted to the hospital. A cardiac computed tomography showed a bullet located adjacent to the right atrium. The transthoracic echocardiography showed a thickened pericardium and septal bouncing motion, which were compatible with constrictive pericarditis. The history of the patient revealed an injury by gunshot during the Korean War in 1950. Radiofrequency ablation of the atrial flutter was performed, and after ablation, the bullet was removed surgically. The patient was discharged home after surgery without complications. PMID:26240588

  3. Gas arc constriction for plasma arc welding

    NASA Technical Reports Server (NTRS)

    McGee, William F. (Inventor); Rybicki, Daniel J. (Inventor)

    1994-01-01

    A welding torch for plasma arc welding apparatus has an inert gas applied circumferentially about the arc column externally of the constricting nozzle so as to apply a constricting force on the arc after it has exited the nozzle orifice and downstream of the auxiliary shielding gas. The constricting inert gas is supplied to a plenum chamber about the body of the torch and exits through a series of circumferentially disposed orifices in an annular wall forming a closure at the forward end of the constricting gas plenum chamber. The constricting force of the circumferential gas flow about the arc concentrates and focuses the arc column into a more narrow and dense column of energy after exiting the nozzle orifice so that the arc better retains its energy density prior to contacting the workpiece.

  4. Enhanced central and conduit pulmonary arterial reservoir function offsets reduced ductal systolic outflow during constriction of the fetal ductus arteriosus.

    PubMed

    Smolich, Joseph J; Penny, Daniel J; Mynard, Jonathan P

    2012-01-01

    Constriction of the fetal ductus arteriosus (DA) has disparate effects on mean and phasic hemodynamics, as mean DA blood flow is preserved until constriction is severe, but DA systolic and diastolic blood velocities change with only mild constriction. To determine the basis of this disparity and its physiological significance, seven anesthetized late-gestation fetal sheep were instrumented with pulmonary trunk (PT), DA, and left pulmonary artery (PA) micromanometer catheters and transit-time flow probes. Blood flow profile and wave intensity analyses were performed at baseline and during mild, moderate, and severe DA constriction (defined as pulmonary-aortic mean pressure differences of 4, 8, and 14 mmHg, respectively), produced with an adjustable snare. With DA constriction, mean DA flow was initially maintained but decreased with severe constriction (P < 0.05) in conjunction with a reduction (P < 0.05) in PT flow (i.e., right ventricular output). By contrast, DA systolic flow fell progressively during DA constriction (P < 0.001), due to decreased transmission of both early and midsystolic proximal flow-enhancing forward-running compression waves into the DA. However, DA constriction was also accompanied by greater systolic storage of blood in the PT and main PA (P < 0.025), and increased retrograde diastolic flow from compliant major branch PA (P < 0.001). Transductal discharge of these central and conduit PA blood reservoirs in diastole offset systolic DA flow reductions. These data suggest that, during DA constriction in the fetus, enhanced central and conduit PA reservoir function constitutes an important compensatory mechanism that contributes to preservation of mean DA flow via a systolic-to-diastolic redistribution of phasic DA flow.

  5. The cardiodepressant and vasodepressant effects of tumour necrosis factor in rat isolated atrial and aortic tissues.

    PubMed Central

    Foulkes, R.; Shaw, S.

    1992-01-01

    1. The ability of recombinant human tumour necrosis factor-alpha (rec huTNF) to elicit cardiodepressor and vasodepressor effects in rat isolated tissues was investigated. 2. rec huTNF (3 x 10(-11)-3 x 10(-8) M) administered directly to the organ bath, caused a concentration-dependent relaxation of the isoprenaline-induced inotropic response in electrically stimulated rat left atria. This occurred within 20 min of administration. In contrast, rec huTNF was without effect on the chronotropic response to isoprenaline in isolated spontaneously beating atria. 3. rec huTNF (1 microgram kg-1) was also given systemically to rats and the atria studied in vitro. Only 60 min of rec huTNF pretreatment was sufficient to cause a marked attenuation of the isoprenaline-induced inotropic response. This effect was not further augmented when rats were pretreated with rec huTNF for 24 h. 4. In isolated aortic rings taken from rats 60 min after rec huTNF (1 microgram kg-1, i.v.) administration, there was no effect seen on the constriction induced by phenylephrine in either endothelium-intact or denuded tissues. In addition, any responses to L-arginine or NG-nitro-L-arginine methyl ester (L-NAME) administration were unaffected by rec huTNF pretreatment. 5. In aortic rings taken from rats 24 h after rec huTNF administration, the phenylephrine-induced constriction was significantly attenuated in tissues with an intact endothelium. Furthermore, the relaxation to subsequent L-arginine administration was greater in these tissues than in those saline-treated rats.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1382789

  6. Pressure Change in an Arterial Constriction

    ERIC Educational Resources Information Center

    Mungan, Carl E.

    2015-01-01

    Consider the following ConcepTest. A platelet is drifting with the blood flowing through a horizontal artery. As the platelet enters a constriction, does the blood pressure increase, decrease, or stay the same?

  7. Pressure Change in an Arterial Constriction

    NASA Astrophysics Data System (ADS)

    Mungan, Carl E.

    2015-12-01

    Consider the following ConcepTest. A platelet is drifting with the blood flowing through a horizontal artery. As the platelet enters a constriction, does the blood pressure increase, decrease, or stay the same?

  8. Persistent right aortic arch in a yearling horse.

    PubMed Central

    Butt, T D; MacDonald, D G; Crawford, W H; Dechant, J E

    1998-01-01

    A 14-month-old filly with chronic pharyngitis was diagnosed with incomplete esophageal constriction and megaesophagus due to a persistent right aortic arch. This report is unusual because clinical signs of respiratory dysfunction secondary to chronic regurgitation occurred prior to the recognition of dysphagia. PMID:9818140

  9. Actin Depolymerization Drives Actomyosin Ring Contraction during Budding Yeast Cytokinesis

    PubMed Central

    Pinto, Inês Mendes; Rubinstein, Boris; Kucharavy, Andrei; Unruh, Jay R.; Li, Rong

    2012-01-01

    SUMMARY Actin filaments and myosin-II are evolutionarily conserved force generating components of the contractile ring during cytokinesis. Here we show that in budding yeast actin filament depolymerization plays a major role in actomyosin ring constriction. Cofilin mutation or chemically stabilizing actin filaments attenuates actomyosin ring constriction. Deletion of myosin-II motor domain or the myosin regulatory light chain reduced the contraction rate and also the rate of actin depolymerization in the ring. We constructed a quantitative microscopic model of actomyosin ring constriction via filament sliding driven by both actin depolymerization and myosin-II motor activity. Model simulations based on experimental measurements supports the notion that actin depolymerization is the predominant mechanism for ring constriction. The model predicts invariability of total contraction time irrespective of the initial ring size as originally reported for C elegans embryonic cells. This prediction was validated in yeast cells of different sizes due to having different ploidies. PMID:22698284

  10. Nanoscale constrictions in superconducting coplanar waveguide resonators

    SciTech Connect

    Jenkins, Mark David; Naether, Uta; Ciria, Miguel; Zueco, David; Luis, Fernando; Sesé, Javier; Atkinson, James; Barco, Enrique del; Sánchez-Azqueta, Carlos; Majer, Johannes

    2014-10-20

    We report on the design, fabrication, and characterization of superconducting coplanar waveguide resonators with nanoscopic constrictions. By reducing the size of the center line down to 50 nm, the radio frequency currents are concentrated and the magnetic field in its vicinity is increased. The device characteristics are only slightly modified by the constrictions, with changes in resonance frequency lower than 1% and internal quality factors of the same order of magnitude as the original ones. These devices could enable the achievement of higher couplings to small magnetic samples or even to single molecular spins and have applications in circuit quantum electrodynamics, quantum computing, and electron paramagnetic resonance.

  11. Mechanics of Constriction during Cell Division: A Variational Approach

    PubMed Central

    Almendro-Vedia, Victor G.; Monroy, Francisco; Cao, Francisco J.

    2013-01-01

    During symmetric division cells undergo large constriction deformations at a stable midcell site. Using a variational approach, we investigate the mechanical route for symmetric constriction by computing the bending energy of deformed vesicles with rotational symmetry. Forces required for constriction are explicitly computed at constant area and constant volume, and their values are found to be determined by cell size and bending modulus. For cell-sized vesicles, considering typical bending modulus of , we calculate constriction forces in the range . The instability of symmetrical constriction is shown and quantified with a characteristic coefficient of the order of , thus evidencing that cells need a robust mechanism to stabilize constriction at midcell. PMID:23990888

  12. Aortic Aneurysm Statistics

    MedlinePlus

    ... Blood Pressure Salt Cholesterol Million Hearts® WISEWOMAN Aortic Aneurysm Fact Sheet Recommend on Facebook Tweet Share Compartir ... cause of most deaths from aortic aneurysms. Aortic Aneurysm in the United States Aortic aneurysms were the ...

  13. Abdominal Aortic Aneurysm (AAA)

    MedlinePlus

    ... Resources Professions Site Index A-Z Abdominal Aortic Aneurysm (AAA) Abdominal aortic aneurysm (AAA) occurs when atherosclerosis ... aortic aneurysm treated? What is an abdominal aortic aneurysm? The aorta, the largest artery in the body, ...

  14. Double aortic arch

    MedlinePlus

    Aortic arch anomaly; Double arch; Congenital heart defect - double aortic arch; Birth defect heart - double aortic arch ... aorta is a single arch that leaves the heart and moves leftward. In double aortic arch, some ...

  15. Aortic Aneurysm

    MedlinePlus

    ... these occur in the part of the aorta running through the chest Abdominal aortic aneurysms (AAA) - these occur in the part of the aorta running through the abdomen Most aneurysms are found during ...

  16. Aortic dissection.

    PubMed

    Nienaber, Christoph A; Clough, Rachel E; Sakalihasan, Natzi; Suzuki, Toru; Gibbs, Richard; Mussa, Firas; Jenkins, Michael T; Thompson, Matt M; Evangelista, Arturo; Yeh, James S M; Cheshire, Nicholas; Rosendahl, Ulrich; Pepper, John

    2016-01-01

    Aortic dissection is a life-threatening condition caused by a tear in the intimal layer of the aorta or bleeding within the aortic wall, resulting in the separation (dissection) of the layers of the aortic wall. Aortic dissection is most common in those 65-75 years of age, with an incidence of 35 cases per 100,000 people per year in this population. Other risk factors include hypertension, dyslipidaemia and genetic disorders that involve the connective tissue, such as Marfan syndrome. Swift diagnostic confirmation and adequate treatment are crucial in managing affected patients. Contemporary management is multidisciplinary and includes serial non-invasive imaging, biomarker testing and genetic risk profiling for aortopathy. The choice of approach for repairing or replacing the damaged region of the aorta depends on the severity and the location of the dissection and the risks of complication from surgery. Open surgical repair is most commonly used for dissections involving the ascending aorta and the aortic arch, whereas minimally invasive endovascular intervention is appropriate for descending aorta dissections that are complicated by rupture, malperfusion, ongoing pain, hypotension or imaging features of high risk. Recent advances in the understanding of the underlying pathophysiology of aortic dissection have led to more patients being considered at substantial risk of complications and, therefore, in need of endovascular intervention rather than only medical or surgical intervention. PMID:27440162

  17. Aortic stenting.

    PubMed

    Droc, Ionel; Calinescu, Francisca Blanca; Droc, Gabriela; Blaj, Catalin; Dammrau, Rolf

    2015-01-01

    The approach to aortic pathology is nowadays more and more endovascular at both thoracic and abdominal levels. Thoracic stenting has gained worldwide acceptance as first intention to treat pathologies of the descending thoracic aorta. Indications have been extended to aortic arch aneurysms and also to diseases of the ascending aorta. The current devices in use for thoracic endovascular repair (TEVAR) are Medtronic Valiant, Gore TAG, Cook Tx2 and Jotec. The choice of the endograft depends on the thoracic aortic pathology and the anatomical suitability. The technological evolution of the abdominal aortic endografts was very rapid, arriving now at the fourth generation. We report the results of 55 elective cases of endovascular abdominal aortic repair (EVAR) performed in two vascular surgical centers in Romania and Germany. The prostheses used were 16 E-vita Abdominal XT, 12 Excluder, eight Talent, seven PowerLink, three Endurant and nine custom-made, fenestrated or branched from Jotec. The mean follow-up was 18 months with CT-scan, duplex ultrasound and contrast-enhanced ultrasound. The mortality was 2%. EVAR tends to become the gold standard for abdominal aortic aneurysm repair. Technological development of the devices with lowest profile introduction systems will permit to extend the anatomical indications to new frontiers. PMID:26200430

  18. FtsZ protofilaments use a hinge-opening mechanism for constrictive force generation.

    PubMed

    Li, Ying; Hsin, Jen; Zhao, Lingyun; Cheng, Yiwen; Shang, Weina; Huang, Kerwyn Casey; Wang, Hong-Wei; Ye, Sheng

    2013-07-26

    The essential bacterial protein FtsZ is a guanosine triphosphatase that self-assembles into a structure at the division site termed the "Z ring". During cytokinesis, the Z ring exerts a constrictive force on the membrane by using the chemical energy of guanosine triphosphate hydrolysis. However, the structural basis of this constriction remains unresolved. Here, we present the crystal structure of a guanosine diphosphate-bound Mycobacterium tuberculosis FtsZ protofilament, which exhibits a curved conformational state. The structure reveals a longitudinal interface that is important for function. The protofilament curvature highlights a hydrolysis-dependent conformational switch at the T3 loop that leads to longitudinal bending between subunits, which could generate sufficient force to drive cytokinesis.

  19. Vowel constrictions are recoverable from formants

    PubMed Central

    Iskarous, Khalil

    2010-01-01

    The area function of the vocal tract in all of its spatial detail is not directly computable from the speech signal. But is partial, yet phonetically distinctive, information about articulation recoverable from the acoustic signal that arrives at the listener’s ear? The answer to this question is important for phonetics, because various theories of speech perception predict different answers. Some theories assume that recovery of articulatory information must be possible, while others assume that it is impossible. However, neither type of theory provides firm evidence showing that distinctive articulatory information is or is not extractable from the acoustic signal. The present study focuses on vowel gestures and examines whether linguistically significant information, such as the constriction location, constriction degree, and rounding, is contained in the speech signal, and whether such information is recoverable from formant parameters. Perturbation theory and linear prediction were combined, in a manner similar to that in Mokhtari (1998) [Mokhtari, P. (1998). An acoustic-phonetic and articulatory study of speech-speaker dichotomy. Doctoral dissertation, University of New South Wales], to assess the accuracy of recovery of information about vowel constrictions. Distinctive constriction information estimated from the speech signal for ten American English vowels were compared to the constriction information derived from simultaneously collected X-ray microbeam articulatory data for 39 speakers [Westbury (1994). Xray microbeam speech production database user’s handbook. University of Wisconsin, Madison, WI]. The recovery of distinctive articulatory information relies on a novel technique that uses formant frequencies and amplitudes, and does not depend on a principal components analysis of the articulatory data, as do most other inversion techniques. These results provide evidence that distinctive articulatory information for vowels can be recovered from the

  20. [Chronic constrictive pericarditis: MR imaging features].

    PubMed

    Dacher, J-N; Caudron, J; Fares, J; Germain, P

    2010-05-01

    Chronic constrictive pericarditis is defined by an increase in the rigidity of the pericardium resulting in impairment of the ventricular filling conditions. Cardiac MR is both a morphological and functional study always complemented by multi-detector CT. Morphological analysis is based on axial, longitudinal long axis and short axis views on Turbo (fast) SE Dark Blood and CINE sequences. Functional analysis is based on real-time acquisitions in the short axis at the base of the ventricles by comparing spontaneous breathing and deep breathing. The excursion of the interventricular septum is a reliable sign of constriction. The study is supplemented by phase contrast acquisitions. In the setting of persistent inflammation or free pericardial fluid, delayed enhancement 3D and 2D sequences including Phase Sensitive Inversion Recovery (PSIR) are useful.

  1. [Aortic aneurysm].

    PubMed

    Villar, Fernando; Pedro-Botet, Juan; Vila, Ramón; Lahoz, Carlos

    2013-01-01

    Aortic aneurysm is one important cause of death in our country. The prevalence of abdominal aortic aneurism (AAA) is around 5% for men older than 50 years of age. Some factors are associated with increased risk for AAA: age, hypertension, hypercholesterolemia, cardiovascular disease and, in particular, smoking. The medical management of patients with an AAA includes cardiovascular risk treatment, particularly smoking cessation. Most of major societies guidelines recommend ultrasonography screening for AAA in men aged 65 to 75 years who have ever smoked because it leads to decreased AAA-specific mortality. PMID:24238836

  2. Constriction of subglacial arteries via supercooling

    NASA Astrophysics Data System (ADS)

    Creyts, T.; Clarke, G.

    2003-04-01

    Beneath many glaciers and ice sheets, hydrology modulates basal processes, including sliding and erosion. Recently, the role of glaciohydraulic supercooling was exposed as an important process in the overdeepening near the toe of Matanuska Glacier, Alaska. Further investigations have shown that supercooling beneath wet-based glaciers occurs in other basins. With discharges for these environments exceeding 0.1 m3 s-1 m-1, one would expect high bedload transport in the glaciohydraulic system. However, recent field studies have shown that bedload transport is supply-limited. This limitation is either caused by a lack of clasts at the glacier's sole, by constricted hydraulic arteries that cannot pass larger clasts, or a combination of these hypotheses. The constriction occurs as a result of either supercooled water condensing and plugging the subglacial arteries, ice overburden pressures enhancing the collapse of pathways, or through a blend of these processes. We investigate these constrictions and the corresponding ice condensation using a numerical model of transient water flow up an overdeepened subglacial water system.

  3. Distinct constrictive processes, separated in time and space, divide caulobacter inner and outer membranes.

    PubMed

    Judd, Ellen M; Comolli, Luis R; Chen, Joseph C; Downing, Kenneth H; Moerner, W E; McAdams, Harley H

    2005-10-01

    Cryoelectron microscope tomography (cryoEM) and a fluorescence loss in photobleaching (FLIP) assay were used to characterize progression of the terminal stages of Caulobacter crescentus cell division. Tomographic cryoEM images of the cell division site show separate constrictive processes closing first the inner membrane (IM) and then the outer membrane (OM) in a manner distinctly different from that of septum-forming bacteria. FLIP experiments had previously shown cytoplasmic compartmentalization (when cytoplasmic proteins can no longer diffuse between the two nascent progeny cell compartments) occurring 18 min before daughter cell separation in a 135-min cell cycle so the two constrictive processes are separated in both time and space. In the very latest stages of both IM and OM constriction, short membrane tether structures are observed. The smallest observed pre-fission tethers were 60 nm in diameter for both the inner and outer membranes. Here, we also used FLIP experiments to show that both membrane-bound and periplasmic fluorescent proteins diffuse freely through the FtsZ ring during most of the constriction procession.

  4. Acute Aortic Syndromes and Thoracic Aortic Aneurysm

    PubMed Central

    Ramanath, Vijay S.; Oh, Jae K.; Sundt, Thoralf M.; Eagle, Kim A.

    2009-01-01

    Acute and chronic aortic diseases have been diagnosed and studied by physicians for centuries. Both the diagnosis and treatment of aortic diseases have been steadily improving over time, largely because of increased physician awareness and improvements in diagnostic modalities. This comprehensive review discusses the pathophysiology and risk factors, classification schemes, epidemiology, clinical presentations, diagnostic modalities, management options, and outcomes of various aortic conditions, including acute aortic dissection (and its variants intramural hematoma and penetrating aortic ulcers) and thoracic aortic aneurysms. Literature searches of the PubMed database were conducted using the following keywords: aortic dissection, intramural hematoma, aortic ulcer, and thoracic aortic aneurysm. Retrospective and prospective studies performed within the past 20 years were included in the review; however, most data are from the past 15 years. PMID:19411444

  5. Constrictive Pericarditis as a Never Ending Story: What's New?

    PubMed Central

    2012-01-01

    Nowadays, we have a better understanding of the natural history of constrictive pericarditis such as transient constriction. In addition, we have acquired the correct understanding of hemodynamic features that are unique to constrictive pericarditis. This understanding has allowed us to diagnose constrictive pericarditis reliably with Doppler echocardiography and differentiation between constrictive pericarditis and restrictive cardiomyopathy is no longer a clinical challenge. The advent of imaging modalities such as CT or MR is another advance in the diagnosis of constrictive pericarditis. We can accurately measure pericardial thickness and additional information such as the status of coronary artery and the presence of myocardial fibrosis can be obtained. We no longer perform cardiac catheterization for the diagnosis of constrictive pericarditis. However, these advances are useless unless we suspect and undergo work-up for constrictive pericarditis. In constrictive pericarditis, the most important diagnostic tool is clinical suspicion. In a patient with signs and symptoms of increased systemic venous pressure i.e. right sided heart failure, that are disproportionate to pulmonary or left sided heart disease, possibility of constrictive pericarditis should always be included in the differential diagnosis. PMID:22493608

  6. Aortic Valve Disease

    MedlinePlus

    ... Disease Tricuspid Valve Disease Cardiac Rhythm Disturbances Thoracic Aortic Aneurysm Pediatric and Congenital Heart Disease Heart abnormalities that ... Disease Tricuspid Valve Disease Cardiac Rhythm Disturbances Thoracic Aortic Aneurysm Aortic Valve Disease Overview The human heart has ...

  7. Asymmetric constriction of dividing Escherichia coli cells induced by expression of a fusion between two min proteins.

    PubMed

    Rowlett, Veronica Wells; Margolin, William

    2014-06-01

    The Min system, consisting of MinC, MinD, and MinE, plays an important role in localizing the Escherichia coli cell division machinery to midcell by preventing FtsZ ring (Z ring) formation at cell poles. MinC has two domains, MinCn and MinCc, which both bind to FtsZ and act synergistically to inhibit FtsZ polymerization. Binary fission of E. coli usually proceeds symmetrically, with daughter cells at roughly 180° to each other. In contrast, we discovered that overproduction of an artificial MinCc-MinD fusion protein in the absence of other Min proteins induced frequent and dramatic jackknife-like bending of cells at division septa, with cell constriction predominantly on the outside of the bend. Mutations in the fusion known to disrupt MinCc-FtsZ, MinCc-MinD, or MinD-membrane interactions largely suppressed bending division. Imaging of FtsZ-green fluorescent protein (GFP) showed no obvious asymmetric localization of FtsZ during MinCc-MinD overproduction, suggesting that a downstream activity of the Z ring was inhibited asymmetrically. Consistent with this, MinCc-MinD fusions localized predominantly to segments of the Z ring at the inside of developing cell bends, while FtsA (but not ZipA) tended to localize to the outside. As FtsA is required for ring constriction, we propose that this asymmetric localization pattern blocks constriction of the inside of the septal ring while permitting continued constriction of the outside portion. PMID:24682325

  8. Asymmetric Constriction of Dividing Escherichia coli Cells Induced by Expression of a Fusion between Two Min Proteins

    PubMed Central

    Rowlett, Veronica Wells

    2014-01-01

    The Min system, consisting of MinC, MinD, and MinE, plays an important role in localizing the Escherichia coli cell division machinery to midcell by preventing FtsZ ring (Z ring) formation at cell poles. MinC has two domains, MinCn and MinCc, which both bind to FtsZ and act synergistically to inhibit FtsZ polymerization. Binary fission of E. coli usually proceeds symmetrically, with daughter cells at roughly 180° to each other. In contrast, we discovered that overproduction of an artificial MinCc-MinD fusion protein in the absence of other Min proteins induced frequent and dramatic jackknife-like bending of cells at division septa, with cell constriction predominantly on the outside of the bend. Mutations in the fusion known to disrupt MinCc-FtsZ, MinCc-MinD, or MinD-membrane interactions largely suppressed bending division. Imaging of FtsZ-green fluorescent protein (GFP) showed no obvious asymmetric localization of FtsZ during MinCc-MinD overproduction, suggesting that a downstream activity of the Z ring was inhibited asymmetrically. Consistent with this, MinCc-MinD fusions localized predominantly to segments of the Z ring at the inside of developing cell bends, while FtsA (but not ZipA) tended to localize to the outside. As FtsA is required for ring constriction, we propose that this asymmetric localization pattern blocks constriction of the inside of the septal ring while permitting continued constriction of the outside portion. PMID:24682325

  9. Constrictive pericarditis after lung transplantation: an under-recognized complication.

    PubMed

    Karolak, Wojtek; Cypel, Marcelo; Chen, Fengshi; Daniel, Lorretta; Chaparro, Cecilia; Keshavjee, Shaf

    2010-05-01

    Primary graft dysfunction, acute rejection, and infection account for most of the early morbidity after lung transplantation, with bronchiolitis obliterans syndrome accounting for most late morbidity. Mediastinal and pericardial complications, in the form of constriction, are not common. We present 4 patients with constrictive pericarditis after lung transplantation and recommend that constrictive pericarditis be considered in the differential diagnosis in lung transplant recipients who present with signs and symptoms of systemic and pulmonary venous congestion. PMID:20207169

  10. Theory of quantum conduction of supercurrent through a constriction

    SciTech Connect

    Furusaki, A.; Takayanagi, H.; Tsukada, M. Nippon Telegraph and Telephone Corporation Basic Research Laboratories, Musashino-shi, Tokyo 180, Japan)

    1991-07-01

    The dc Josephson current through a constriction in a two-dimensional superconductor-semiconductor-superconductor junction is calculated. It is shown that when the Fermi wavelength is comparable with the width of the constriction, the critical current shows a steplike variation as a function of the width of the constriction; this is reminiscent of the quantization of the normal-state conductance of point contacts in a two-dimensional electron gas.

  11. Control of closure/constriction duration in lingual consonants

    NASA Astrophysics Data System (ADS)

    Lofqvist, Anders

    2003-10-01

    This study examines tongue movements in the production of lingual consonants where the duration of the oral closure/constriction is varied for linguistic purposes. Earlier work has shown that the tongue continues to move during the closure/constriction. The magnitude of the movement path during the closure/constriction is influenced by the vowel environment. Since the tongue has to stay in contact with the hard palate to maintain the closure/constriction, one might expect that the movement during the closure will be about the same for short and long consonants. To maintain the contact, a speaker would thus have to make a slower movement for the long consonants. Tongue and jaw movements were recorded in native Japanese speakers using a magnetometer system. Preliminary results for three speakers show that the closure/constriction duration for the long consonants was usually more than twice as long as that for the short consonants. The results also show a slightly longer movement path during the closure/constriction for the long consonants. As expected, the average speed of the tongue movement during the closure/constriction was systematically slower for the long consonants. In addition there was a positive correlation between closure/constriction duration and the path during the closure/constriction. [Work supported by NIH.

  12. Snake modulates constriction in response to prey's heartbeat.

    PubMed

    Boback, Scott M; Hall, Allison E; McCann, Katelyn J; Hayes, Amanda W; Forrester, Jeffrey S; Zwemer, Charles F

    2012-06-23

    Many species of snakes use constriction-the act of applying pressure via loops of their trunk-to subdue and kill their prey. Constriction is costly and snakes must therefore constrict their prey just long enough to ensure death. However, it remains unknown how snakes determine when their prey is dead. Here, we demonstrate that boas (Boa constrictor) have the remarkable ability to detect a heartbeat in their prey and, based on this signal, modify the pressure and duration of constriction accordingly. We monitored pressure generated by snakes as they struck and constricted warm cadaveric rats instrumented with a simulated heart. Snakes responded to the beating heart by constricting longer and with greater total pressure than when constricting rats with no heartbeat. When the heart was stopped midway through the constriction, snakes abandoned constriction shortly after the heartbeat ceased. Furthermore, snakes naive to live prey also responded to the simulated heart, suggesting that this behaviour is at least partly innate. These results are an example of how snakes integrate physiological cues from their prey to modulate a complex and ancient behavioural pattern.

  13. Simulations of gravity-induced trapping of a deformable drop in a three-dimensional constriction.

    PubMed

    Ratcliffe, Thomas; Zinchenko, Alexander Z; Davis, Robert H

    2012-10-01

    An efficient algorithm is developed to determine the three-dimensional shape of a deformable drop trapped under gravity in a constriction, employing an artificial evolution to a steady state. During the simulation, the drop surface is advanced using a rationally-devised normal "velocity", based on local deviation from the Young-Laplace equation and the adjacent solid shape, to approach the trapped drop shape. The artificial "time-dependent" evolution of the drop to the static, trapped shape requires that the free portions of the drop interface eventually satisfy the Young-Laplace equation, and the drop-solid contact portions of the drop interface conform to the solid surface. The significant advantage of this solution method is that a simple, numerically-efficient "velocity" is used to construct the evolution to the steady state; the coated areas where the drop is in near contact with solid boundaries of the constriction do not have to be specified a priori, but are found in the course of the solution. Alternative methods (e.g., boundary integral) based on realistic time-marching would be much more costly for determining the trapped state. Trapping conditions and drop shapes are studied for gravity-induced settling of a deformable drop into a three-dimensional constriction. For conditions near critical, where the trapped-drop steady state ceases to exist, severe surface-mesh distortions are treated by a combination of 'passive mesh stabilization', mesh relaxation and topological mesh transformations through node reconnections. For Bond numbers above a critical value, the drop is deformable enough to pass through the hole of the constriction, with no trapping. Critical Bond numbers are determined by linearly fitting minima of the root-mean-squared (rms) surface velocities versus corresponding Bond numbers greater than critical, and then extrapolating the Bond number to where the minimum rms velocity is zero (i.e., the drop becomes trapped). For ring and hyperbolic

  14. Effects of silver ions (Ag+) on contractile ring function and microtubule dynamics during first cleavage in Ilyanassa obsoleta

    NASA Technical Reports Server (NTRS)

    Conrad, A. H.; Stephens, A. P.; Paulsen, A. Q.; Schwarting, S. S.; Conrad, G. W.; Spooner, B. S. (Principal Investigator)

    1994-01-01

    The terminal phase of cell division involves tight constriction of the cleavage furrow contractile ring, stabilization/elongation of the intercellular bridge, and final separation of the daughter cells. At first cleavage, the fertilized eggs of the mollusk, Ilyanassa obsoleta, form two contractile rings at right angles to each other in the same cytoplasm that constrict to tight necks and partition the egg into a trefoil shape. The cleavage furrow contractile ring (CF) normally constricts around many midbody microtubules (MTs) and results in cleavage; the polar lobe constriction contractile ring (PLC) normally constricts around very few MTs and subsequently relaxes without cleavage. In the presence of Ag+ ions, the PLC 1) begins MT-dependent rapid constriction sooner than controls, 2) encircles more MTs than control egg PLCs, 3) elongates much more than control PLCs, and 4) remains tightly constricted and effectively cleaves the polar lobe from the egg. If Ag(+)-incubated eggs are returned to normal seawater at trefoil, tubulin fluorescence disappears from the PLC neck and the neck relaxes. If nocodazole, a drug that depolymerizes MTs, is added to Ag(+)-incubated eggs during early PLC constriction, the PLC is not stabilized and eventually relaxes. However, if nocodazole is added to Ag(+)-incubated eggs at trefoil, tubulin fluorescence disappears from the PLC neck but the neck remains constricted. These results suggest that Ag+ accelerates and gradually stabilizes the PLC constriction by a mechanism that is initially MT-dependent, but that progressively becomes MT-independent.

  15. Study of the effect of thiols on the vasodilatory potency of S-nitrosothiols by using a modified aortic ring assay.

    PubMed

    Giustarini, Daniela; Tsikas, Dimitrios; Rossi, Ranieri

    2011-10-15

    Both low-molecular-mass thiols (LMM-SH) and protein thiols (P-SH) can modulate the biological activity of S-nitrosothiols (RSNO) via S-transnitrosation reactions. It has been difficult to evaluate the entity of this effect in blood circulation by in vitro assays with isolated aorta rings so far, because media rich in proteins cannot be used due to the foaming as a consequence of the needed gas bubbling. We have modified the original apparatus for organ bioassay in order to minimize foaming and to increase analytical performance. By using this modified bioassay we investigated the vasodilatory potency of various endogenous RSNOs in the presence of physiologically relevant concentrations of albumin and LMM-SH. Our results show that the sulfhydryl group of the cysteine moiety of albumin and LMM-SH has a dramatic effect on the vasodilatory potency of RSNO. Considering the equilibrium constants for S-transnitrosation reactions and the concentration of P-SH and LMM-SH we measured in healthy humans (aged 18-85 years), we infer that the age-dependency of hematic levels of LMM-SH may have a considerable impact in RSNO-mediated vasodilation. S-Nitrosoproteins such as S-nitrosoalbumin may constitute a relatively silent and constant amount of circulating RSNO. On the other hand, LMM-SH may mediate and control the biological actions of S-nitrosoproteins via S-transnitrosation reactions, by forming more potent nitric oxide-releasing LMM-S-nitrosothiols. Lifestyle habits, status of health and individual age are proven factors that, in turn, may influence the concentration of these compounds. These aspects should be taken into consideration when testing the vasodilatory effects of RSNO in pre-clinical studies.

  16. The role of microtubules in contractile ring function

    NASA Technical Reports Server (NTRS)

    Conrad, A. H.; Paulsen, A. Q.; Conrad, G. W.; Spooner, B. S. (Principal Investigator)

    1992-01-01

    During cytokinesis, a cortical contractile ring forms around a cell, constricts to a stable tight neck and terminates in separation of the daughter cells. At first cleavage, Ilyanassa obsoleta embryos form two contractile rings simultaneously. The cleavage furrow (CF), in the animal hemisphere between the spindle poles, constricts to a stable tight neck and separates the daughter cells. The third polar lobe constriction (PLC-3), in the vegetal hemisphere below the spindle, constricts to a transient tight neck, but then relaxes, allowing the polar lobe cytoplasm to merge with one daughter cell. Eggs exposed to taxol, a drug that stabilizes microtubules, before the CF or the PLC-3 develop, fail to form CFs, but form stabilized tight PLCs. Eggs exposed to taxol at the time of PLC-3 formation develop varied numbers of constriction rings in their animal hemispheres and one PLC in their vegetal hemisphere, none of which relax. Eggs exposed to taxol after PLC-3 initiation form stabilized tight CFs and PLCs. At maximum constriction, control embryos display immunolocalization of nonextractable alpha-tubulin in their CFs, but not in their PLCs, and reveal, via electron microscopy, many microtubules extending through their CFs, but not through their PLCs. Embryos which form stabilized tightly constricted CFs and PLCs in the presence of taxol display immunolocalization of nonextractable alpha-tubulin in both constrictions and show many polymerized microtubules extending through both CFs and PLCs. These results suggest that the extension of microtubules through a tight contractile ring may be important for stabilizing that constriction and facilitating subsequent cytokinesis.

  17. Cardiac-MRI demonstration of the ligamentum arteriosum in a case of right aortic arch with aberrant left subclavian artery.

    PubMed

    Paparo, Francesco; Bacigalupo, Lorenzo; Melani, Enrico; Rollandi, Gian Andrea; Caro, Giovanni De

    2012-05-28

    Right-sided aortic arch with aberrant left subclavian artery (RAA/ALSC) is the second most common mediastinal complete vascular ring. Adult presentation of dysphagia lusoria due to a RAA/ALSC is uncommon with fewer than 25 cases reported in the world literature. The left lateral portion of this vascular ring is not a vessel, but an atretic ductus arteriosus, the ligamentum arteriosum, which has been identified in different cases as the major cause of tracheo-esophageal impingement. Surgical division of the ligamentum arteriosum allows the vessels to assume a less constricting pattern decreasing dysphagic symptoms. Clear visualization of the ligamentum arteriosum by diagnostic imaging has not been obtained in previously reported cases. We demonstrated, using magnetic resonance imaging, the location and the complete course of a left-sided ligamentum arteriosum in a patient with adult-onset dysphagia due to a RAA/ALSC with a small Kommerell's diverticulum, providing, during the same session, a complete assessment of both mediastinal vascular abnormalities and esophageal impingement sites.

  18. Viscoelastic effects on electrokinetic particle focusing in a constricted microchannel

    PubMed Central

    Lu, Xinyu; DuBose, John; Joo, Sang Woo; Qian, Shizhi

    2015-01-01

    Focusing suspended particles in a fluid into a single file is often necessary prior to continuous-flow detection, analysis, and separation. Electrokinetic particle focusing has been demonstrated in constricted microchannels by the use of the constriction-induced dielectrophoresis. However, previous studies on this subject have been limited to Newtonian fluids only. We report in this paper an experimental investigation of the viscoelastic effects on electrokinetic particle focusing in non-Newtonian polyethylene oxide solutions through a constricted microchannel. The width of the focused particle stream is found NOT to decrease with the increase in DC electric field, which is different from that in Newtonian fluids. Moreover, particle aggregations are observed at relatively high electric fields to first form inside the constriction. They can then either move forward and exit the constriction in an explosive mode or roll back to the constriction entrance for further accumulations. These unexpected phenomena are distinct from the findings in our earlier paper [Lu et al., Biomicrofluidics 8, 021802 (2014)], where particles are observed to oscillate inside the constriction and not to pass through until a chain of sufficient length is formed. They are speculated to be a consequence of the fluid viscoelasticity effects. PMID:25713690

  19. Snake constriction rapidly induces circulatory arrest in rats.

    PubMed

    Boback, Scott M; McCann, Katelyn J; Wood, Kevin A; McNeal, Patrick M; Blankenship, Emmett L; Zwemer, Charles F

    2015-07-01

    As legless predators, snakes are unique in their ability to immobilize and kill their prey through the process of constriction, and yet how this pressure incapacitates and ultimately kills the prey remains unknown. In this study, we examined the cardiovascular function of anesthetized rats before, during and after being constricted by boas (Boa constrictor) to examine the effect of constriction on the prey's circulatory function. The results demonstrate that within 6 s of being constricted, peripheral arterial blood pressure (PBP) at the femoral artery dropped to 1/2 of baseline values while central venous pressure (CVP) increased 6-fold from baseline during the same time. Electrocardiographic recordings from the anesthetized rat's heart revealed profound bradycardia as heart rate (fH) dropped to nearly half of baseline within 60 s of being constricted, and QRS duration nearly doubled over the same time period. By the end of constriction (mean 6.5±1 min), rat PBP dropped 2.9-fold, fH dropped 3.9-fold, systemic perfusion pressure (SPP=PBP-CVP) dropped 5.7-fold, and 91% of rats (10 of 11) had evidence of cardiac electrical dysfunction. Blood drawn immediately after constriction revealed that, relative to baseline, rats were hyperkalemic (serum potassium levels nearly doubled) and acidotic (blood pH dropped from 7.4 to 7.0). These results are the first to document the physiological response of prey to constriction and support the hypothesis that snake constriction induces rapid prey death due to circulatory arrest.

  20. Cellular mechanisms mediating rat renal microvascular constriction by angiotensin II.

    PubMed Central

    Takenaka, T; Suzuki, H; Fujiwara, K; Kanno, Y; Ohno, Y; Hayashi, K; Nagahama, T; Saruta, T

    1997-01-01

    To assess cellular mechanisms mediating afferent (AA) and efferent arteriolar (EA) constriction by angiotensin II (AngII), experiments were performed using isolated perfused hydronephrotic kidneys. In the first series of studies, AngII (0.3 nM) constricted AAs and EAs by 29+/-3 (n = 8, P < 0.01) and 27+/-3% (n = 8, P < 0.01), respectively. Subsequent addition of nifedipine restored AA but not EA diameter. Manganese (8 mM) reversed EA constriction by 65+/-9% (P < 0.01). In the second group, the addition of N-ethylmaleimide (10 microM), a Gi/Go protein antagonist, abolished AngII- induced EA (n = 6) but not AA constriction (n = 6). In the third series of experiments, treatment with 2-nitro-4-carboxyphenyl-N, N-diphenyl-carbamate (200 microM), a phospholipase C inhibitor, blocked both AA and EA constriction by AngII (n = 6 for each). In the fourth group, thapsigargin (1 microM) prevented AngII-induced AA constriction (n = 8) and attenuated EA constriction (8+/-2% decrease in EA diameter at 0.3 nM AngII, n = 8, P < 0.05). Subsequent addition of manganese (8 mM) reversed EA constriction. Our data provide evidence that in AAs, AngII stimulates phospholipase C with subsequent calcium mobilization that is required to activate voltage-dependent calcium channels. Our results suggest that AngII constricts EAs by activating phospholipase C via the Gi protein family, thereby eliciting both calcium mobilization and calcium entry. PMID:9329977

  1. Furrow Constriction in Animal Cell Cytokinesis

    PubMed Central

    Turlier, Hervé; Audoly, Basile; Prost, Jacques; Joanny, Jean-François

    2014-01-01

    Cytokinesis is the process of physical cleavage at the end of cell division; it proceeds by ingression of an acto-myosin furrow at the equator of the cell. Its failure leads to multinucleated cells and is a possible cause of tumorigenesis. Here, we calculate the full dynamics of furrow ingression and predict cytokinesis completion above a well-defined threshold of equatorial contractility. The cortical acto-myosin is identified as the main source of mechanical dissipation and active forces. Thereupon, we propose a viscous active nonlinear membrane theory of the cortex that explicitly includes actin turnover and where the active RhoA signal leads to an equatorial band of myosin overactivity. The resulting cortex deformation is calculated numerically, and reproduces well the features of cytokinesis such as cell shape and cortical flows toward the equator. Our theory gives a physical explanation of the independence of cytokinesis duration on cell size in embryos. It also predicts a critical role of turnover on the rate and success of furrow constriction. Scaling arguments allow for a simple interpretation of the numerical results and unveil the key mechanism that generates the threshold for cytokinesis completion: cytoplasmic incompressibility results in a competition between the furrow line tension and the cell poles’ surface tension. PMID:24411243

  2. Understanding cell passage through constricted microfluidic channels

    NASA Astrophysics Data System (ADS)

    Cartas-Ayala, Marco A.; Karnik, Rohit

    2012-11-01

    Recently, several microfluidic platforms have been proposed to characterize cells based on their behaviour during cell passage through constricted channels. Variables like transit time have been analyzed in disease states like sickle cell anemia, malaria and sepsis. Nevertheless, it is hard to make direct comparisons between different platforms and cell types. We present experimental results of the relationship between solid deformable particle properties, i.e. stiffness and relative particle size, and flow properties, i.e. particle's velocity. We measured the hydrodynamic variables during the flow of HL-60 cells, a white myeloid cell type, in narrow microfluidic square channels using a microfluidic differential manometer. We measured the flow force required to move cells of different sizes through microchannels and quantified friction forces opposing cell passage. We determined the non-dimensional parameters that influence the flow of cells and we used them to obtain a non dimensional expression that can be used to predict the forces needed to drive cells through microchannels. We found that the friction force needed to flow HL-60 through a microfluidic channel is the sum of two parts. The first part is a static friction force that is proportional to the force needed to keep the force compressed. The second part is a factor that is proportional to the cell velocity, hence a dynamic term, and slightly sensitive to the compressive force. We thank CONACYT (Mexican Science and Technology Council) for supporting this project, grant 205899.

  3. Constrictive pericarditis associated with Marlex mesh. Two case reports.

    PubMed

    Chen, R F; Lai, C P

    2001-01-01

    Two patients were referred to our hospital with constrictive pericarditis approximately 1 year after undergoing mitral valve repair at another institution. Both repairs had included the use of a pericardial substitute, Marlex mesh, to prevent adhesion and to facilitate possible reoperations. Computed tomography and cardiac catheterization were used to establish the diagnosis of constrictive pericarditis. During surgery, dense, thickened fibrous tissue, the result of a Marlex mesh-related reaction, was found tightly adhered to the epicardium in each of the patients. It appeared that the Marlex mesh, which had been inserted to facilitate reoperation, had contributed to the development of constrictive pericarditis. PMID:11330746

  4. Constrictive Pericarditis Associated with Marlex Mesh: Two Case Reports

    PubMed Central

    Chen, Robert F.; Lai, Cha Po

    2001-01-01

    Two patients were referred to our hospital with constrictive pericarditis approximately 1 year after undergoing mitral valve repair at another institution. Both repairs had included the use of a pericardial substitute, Marlex mesh, to prevent adhesion and to facilitate possible reoperations. Computed tomography and cardiac catheterization were used to establish the diagnosis of constrictive pericarditis. During surgery, dense, thickened fibrous tissue, the result of a Marlex mesh-related reaction, was found tightly adhered to the epicardium in each of the patients. It appeared that the Marlex mesh, which had been inserted to facilitate reoperation, had contributed to the development of constrictive pericarditis. PMID:11330746

  5. Balloon aortic valvuloplasty.

    PubMed

    Wang, A; Harrison, J K; Bashore, T M

    1997-01-01

    Balloon aortic valvuloplasty is a percutaneous, therapeutic option for patients with severe aortic stenosis, yet the effectiveness of this procedure is dependent on the morphology of the stenotic aortic valve and the respective mechanism of dilation. In younger patients with congenital aortic stenosis, acute and intermediate-term results are good. However, in adult patients, in whom degenerative aortic stenosis is the most common cause, the acute clinical and hemodynamic benefits of balloon aortic valvuloplasty are not lasting, as restenosis occurs in most patients within 6 months. Sympatomatic relief for adults undergoing balloon aortic valvuloplasty is only apparent in patients with normal left ventricular function, who generally are also candidates for aortic valve replacement. Furthermore, the long-term survival for adults after balloon aortic valvuloplasty is similar to the natural history of untreated severe aortic stenosis. In this article, the mechanism of balloon aortic valvuloplasty, as well as its clinical and hemodynamic effects, are reviewed in the context of the different morphological types of aortic stenosis. In addition, two large registries of adult patients treated with balloon aortic valvuloplasty provide important information regarding the acute and long-term results of this procedure and are reviewed.

  6. Aortic Annular Enlargement during Aortic Valve Replacement

    PubMed Central

    Dumani, Selman; Likaj, Ermal; Dibra, Laureta; Llazo, Stavri; Refatllari, Ali

    2016-01-01

    In the surgery of aortic valve replacement is always attempted, as much as possible, to implant the larger prosthesis with the mains goals to enhance the potential benefits, to minimise transvalvular gradient, decrease left ventricular size and avoid the phenomenon of patient-prosthesis mismatch. Implantation of an ideal prosthesis often it is not possible, due to a small aortic annulus. A variety of aortic annulus enlargement techniques is reported to avoid patient-prosthesis mismatch. We present the case that has submitted four three times open heart surgery. We used Manouguian technique to enlarge aortic anulus with excellent results during the fourth time of surgery. PMID:27703574

  7. Fluid dynamics of aortic valve stenosis

    NASA Astrophysics Data System (ADS)

    Keshavarz-Motamed, Zahra; Maftoon, Nima

    2009-11-01

    Aortic valve stenosis, which causes considerable constriction of the flow passage, is one of the most frequent cardiovascular diseases and is the most common cause of the valvular replacements which take place for around 100,000 per year in North America. Furthermore, it is considered as the most frequent cardiac disease after arterial hypertension and coronary artery disease. The objective of this study is to develop an analytical model considering the coupling effect between fluid flow and elastic deformation with reasonable boundary conditions to describe the effect of AS on the left ventricle and the aorta. The pulsatile and Newtonian blood flow through aortic stenosis with vascular wall deformability is analyzed and its effects are discussed in terms of flow parameters such as velocity, resistance to flow, shear stress distribution and pressure loss. Meanwhile we developed analytical expressions to improve the comprehension of the transvalvular hemodynamics and the aortic stenosis hemodynamics which is of great interest because of one main reason. To medical scientists, an accurate knowledge of the mechanical properties of whole blood flow in the aorta can suggest a new diagnostic tool.

  8. Forced transport of deformable containers through narrow constrictions.

    PubMed

    Kusters, Remy; van der Heijden, Thijs; Kaoui, Badr; Harting, Jens; Storm, Cornelis

    2014-09-01

    We study, numerically and analytically, the forced transport of deformable containers through a narrow constriction. Our central aim is to quantify the competition between the constriction geometry and the active forcing, regulating whether and at which speed a container may pass through the constriction and under what conditions it gets stuck. We focus, in particular, on the interrelation between the force that propels the container and the radius of the channel, as these are the external variables that may be directly controlled in both artificial and physiological settings. We present lattice Boltzmann simulations that elucidate in detail the various phases of translocation and present simplified analytical models that treat two limiting types of these membrane containers: deformational energy dominated by the bending or stretching contribution. In either case we find excellent agreement with the full simulations, and our results reveal that not only the radius but also the length of the constriction determines whether or not the container will pass.

  9. Abdominal Aortic Aneurysms: Treatments

    MedlinePlus

    ... information Membership Directory (SIR login) Interventional Radiology Abdominal Aortic Aneurysms Interventional Radiologists Treat Abdominal Aneurysms Nonsurgically Interventional radiologists ...

  10. Wall shear stress estimates in coronary artery constrictions

    NASA Technical Reports Server (NTRS)

    Back, L. H.; Crawford, D. W.

    1992-01-01

    Wall shear stress estimates from laminar boundary layer theory were found to agree fairly well with the magnitude of shear stress levels along coronary artery constrictions obtained from solutions of the Navier Stokes equations for both steady and pulsatile flow. The relatively simple method can be used for in vivo estimates of wall shear stress in constrictions by using a vessel shape function determined from a coronary angiogram, along with a knowledge of the flow rate.

  11. ED 02-3 CLINICAL IMPLICATIONS OF CENTRAL HEMODYNAMICS ON AORTIC AND END-ORGAN DISEASES.

    PubMed

    Hashimoto, Junichiro

    2016-09-01

    The central aorta constitutes the main trunk of the systemic arterial tree. It dilates passively with cardiac ejection during systole and then constricts with its recoil function during diastole, thereby regulating blood pressure and blood flow. The central pulsatile hemodynamics affects local hemodynamics within as well as downstream of the aorta (e.g., end organs).The aorta progressively stiffens and dilates with advancing age, and such age-dependent change is accelerated by hypertension. According to the law of Laplace, wall stress depends on the diameter and pressure of the blood vessel. This has been confirmed by substantial studies which have associated baseline aortic diameter with subsequent development of aortic dissection and progressive dilatation of aortic lumen. This law can also imply potential importance of local pressure within the aorta (i.e., the central pressure) in predicting the development and progression of aortic aneurysms.Several previous studies have shown that hypertension (together with age and obesity) is related to dilatation of the proximal ascending aorta (rather than of the aortic root). In addition, aortic blood flow abnormality may also be importantly related to aortic dilatation because of strong positive association between the diastole flow reversal and lumen diameter in the proximal thoracic aorta. As for the abdominal (infrarenal) aorta, aneurysmal development and progression have been attributed to aortic segmental stiffening (of the bifurcational versus infrarenal segment) and aortic pressure elevation, respectively.Central pulsatile pressure not only represents aortic wall stress but also determines cardiac afterload and microvascular wall stress in the brain and kidney. Central pulsatile flow (in both directions) could also affect the flow distribution into the upper and lower parts of the body and control end-organ function. Aortic structural change (including segmental stiffening and aneurysmal formation) causes central

  12. ED 02-3 CLINICAL IMPLICATIONS OF CENTRAL HEMODYNAMICS ON AORTIC AND END-ORGAN DISEASES.

    PubMed

    Hashimoto, Junichiro

    2016-09-01

    The central aorta constitutes the main trunk of the systemic arterial tree. It dilates passively with cardiac ejection during systole and then constricts with its recoil function during diastole, thereby regulating blood pressure and blood flow. The central pulsatile hemodynamics affects local hemodynamics within as well as downstream of the aorta (e.g., end organs).The aorta progressively stiffens and dilates with advancing age, and such age-dependent change is accelerated by hypertension. According to the law of Laplace, wall stress depends on the diameter and pressure of the blood vessel. This has been confirmed by substantial studies which have associated baseline aortic diameter with subsequent development of aortic dissection and progressive dilatation of aortic lumen. This law can also imply potential importance of local pressure within the aorta (i.e., the central pressure) in predicting the development and progression of aortic aneurysms.Several previous studies have shown that hypertension (together with age and obesity) is related to dilatation of the proximal ascending aorta (rather than of the aortic root). In addition, aortic blood flow abnormality may also be importantly related to aortic dilatation because of strong positive association between the diastole flow reversal and lumen diameter in the proximal thoracic aorta. As for the abdominal (infrarenal) aorta, aneurysmal development and progression have been attributed to aortic segmental stiffening (of the bifurcational versus infrarenal segment) and aortic pressure elevation, respectively.Central pulsatile pressure not only represents aortic wall stress but also determines cardiac afterload and microvascular wall stress in the brain and kidney. Central pulsatile flow (in both directions) could also affect the flow distribution into the upper and lower parts of the body and control end-organ function. Aortic structural change (including segmental stiffening and aneurysmal formation) causes central

  13. Flow in an Aortic Coarctation

    NASA Astrophysics Data System (ADS)

    Loma, Luis; Miller, Paul; Hertzberg, Jean

    2009-11-01

    Coarctation of the aorta is a congenital cardiovascular defect that causes a constriction in the descending thoracic aorta. To gain a better understanding of the cause of post-surgical problems, a rigid glass and a compliant in vitro model of the aortic arch and descending aorta with a coarctation were constructed. Near-physiologic compliance was obtained using a silicone elastomer. Stereoscopic PIV was used to obtain 3D velocity maps. Results show a high speed turbulent jet formed at the exit of the coarctation. Flow in the rigid model was significantly different from in the compliant model. In the rigid model, the jet was symmetric, creating a toroidal recirculation area. In the compliant model, the jet was directed towards the medial wall, inducing flow reversal only at the lateral wall. Peak velocities and turbulence intensities were higher in the rigid model, however shear rate values in the compliant model were significantly above both the rigid model and normal in vivo values at the medial wall. In both models the reattachment region fluctuated, creating oscillatory shear.

  14. Isolation of microorganisms using sub-micrometer constrictions.

    PubMed

    Tandogan, Nil; Abadian, Pegah N; Epstein, Slava; Aoi, Yoshiteru; Goluch, Edgar D

    2014-01-01

    We present an automated method for isolating pure bacterial cultures from samples containing multiple species that exploits the cell's own physiology to perform the separation. Cells compete to reach a chamber containing nutrients via a constriction whose cross-sectional area only permits a single cell to enter, thereby blocking the opening and preventing other cells from entering. The winning cell divides across the constriction and its progeny populate the chamber. The devices are passive and require no user interaction to perform their function. Device fabrication begins with the creation of a master mold that contains the desired constriction and chamber features. Replica molding is used to create patterned polymer chips from the master, which are bonded to glass microscope cover slips to create the constrictions. We tested constriction geometries ranging from 500 nanometers to 5 micrometers in width, 600 to 950 nanometers in height, and 10 to 40 micrometers in length. The devices were used to successfully isolate a pure Pseudomonas aeruginosa culture from a mixture that also contained Escherichia coli. We demonstrated that individual strains of the same species can be separated out from mixtures using red and green fluorescently-labeled E. coli. We also used the devices to isolate individual environmental species. Roseobacter sp. was separated from another marine species, Psychroserpens sp.

  15. Asymmetrical quartz crystallographic fabrics formed during constrictional deformation

    NASA Astrophysics Data System (ADS)

    Sullivan, W. A.; Beane, R. J.

    2010-10-01

    Numerical simulations predict unique quartz crystallographic fabric patterns for plane strain, flattening, and constriction. Multiple studies support the predictions for plane strain and flattening. To test predictions for constriction, this paper analyzes five examples of quartz crystallographic fabrics from a 1-km-wide domain of L tectonites in the Pigeon Point high-strain zone, Klamath Mountains, California, U.S.A. These samples were deformed under greenschist- to amphibolite-facies conditions. Quartz c-axis fabrics are similar to the predicted double-girdle fabrics except that amphibolite-facies samples exhibit c-axis maxima and are distinctly asymmetrical about the elongation lineations. Activation of different slip systems combined with small deviations from pure constriction account for the c-axis maxima, and noncoaxial flow accounts for the fabric asymmetry. The simple-shear component is randomly oriented in geographic coordinates throughout the domain of L tectonites. These data confirm that numerical simulations predict the quartz c-axis fabric geometry developed during constriction for some deformation conditions, and they confirm the quartz a-axis patterns predicted for constriction for the first time. These data also demonstrate that the relationship between quartz crystallographic fabrics and strain geometry is not straightforward, and they indicate that a-axis fabrics may be more useful indicators of strain geometry variations.

  16. Granular flow over inclined channels with constrictions

    NASA Astrophysics Data System (ADS)

    Tunuguntla, Deepak; Weinhart, Thomas; Thornton, Anthony; Bokhove, Onno

    2013-04-01

    Study of granular flows down inclined channels is essential in understanding the dynamics of natural grain flows like landslides and snow avalanches. As a stepping stone, dry granular flow over an inclined channel with a localised constriction is investigated using both continuum methods and particle simulations. Initially, depth-averaged equations of motion (Savage & Hutter 1989) containing an unknown friction law are considered. The shallow-layer model for granular flows is closed with a friction law obtained from particle simulations of steady flows (Weinhart et al. 2012) undertaken in the open source package Mercury DPM (Mercury 2010). The closed two-dimensional (2D) shallow-layer model is then width-averaged to obtain a novel one-dimensional (1D) model which is an extension of the one for water flows through contraction (Akers & Bokhove 2008). Different flow states are predicted by this novel one-dimensional theory. Flow regimes with distinct flow states are determined as a function of upstream channel Froude number, F, and channel width ratio, Bc. The latter being the ratio of the channel exit width and upstream channel width. Existence of multiple steady states is predicted in a certain regime of F - Bc parameter plane which is in agreement with experiments previously undertaken by (Akers & Bokhove 2008) and for granular flows (Vreman et al. 2007). Furthermore, the 1D model is verified by solving the 2D shallow granular equations using an open source discontinuous Galerkin finite element package hpGEM (Pesch et al. 2007). For supercritical flows i.e. F > 1 the 1D asymptotics holds although the two-dimensional oblique granular jumps largely vary across the converging channel. This computationally efficient closed 1D model is validated by comparing it to the computationally more expensiveaa three-dimensional particle simulations. Finally, we aim to present a quasi-steady particle simulation of inclined flow through two rectangular blocks separated by a gap

  17. Acute aortic syndrome

    PubMed Central

    2016-01-01

    Acute aortic syndrome (AAS) is a term used to describe a constellation of life-threatening aortic diseases that have similar presentation, but appear to have distinct demographic, clinical, pathological and survival characteristics. Many believe that the three major entities that comprise AAS: aortic dissection (AD), intramural hematoma (IMH) and penetrating aortic ulcer (PAU), make up a spectrum of aortic disease in which one entity may evolve into or coexist with another. Much of the confusion in accurately classifying an AAS is that they present with similar symptoms: typically acute onset of severe chest or back pain, and may have similar radiographic features, since the disease entities all involve injury or disruption of the medial layer of the aortic wall. The accurate diagnosis of an AAS is often made at operation. This manuscript will attempt to clarify the similarities and differences between AD, IMH and PAU of the ascending aorta and describe the challenges in distinguishing them from one another. PMID:27386405

  18. Para-aortic lymphocyst.

    PubMed

    Helmkamp, B F; Krebs, H B; Isikoff, M B; Poliakoff, S R; Averette, H E

    1980-10-15

    Although numerous articles regarding the etiology, incidence, complications, and management of pelvic lymphocysts have been published in the American literature since 1958, there has been no mention of para-aortic lymphocyst as a complication of para-aortic node dissection. Two recent cases of symptomatic para-aortic lymphocyst have prompted a review of our para-aortic node dissection technique when this procedure is not combined with a more extensive pelvic lymphadenectomy. Our modification in technique is to use retroperitoneal para-aortic drainage by constant pressure-controlled suction following closure of the posterior parietal peritoneum, and the results in our first 15 patients are presented. There were no complications related to the drainage technique. Abdominal ultrasound and intravenous urography have proved to be excellent diagnostic tools in the initial evaluation and subsequent follow-up of para-aortic lymphocytes.

  19. Acute aortic syndrome.

    PubMed

    Corvera, Joel S

    2016-05-01

    Acute aortic syndrome (AAS) is a term used to describe a constellation of life-threatening aortic diseases that have similar presentation, but appear to have distinct demographic, clinical, pathological and survival characteristics. Many believe that the three major entities that comprise AAS: aortic dissection (AD), intramural hematoma (IMH) and penetrating aortic ulcer (PAU), make up a spectrum of aortic disease in which one entity may evolve into or coexist with another. Much of the confusion in accurately classifying an AAS is that they present with similar symptoms: typically acute onset of severe chest or back pain, and may have similar radiographic features, since the disease entities all involve injury or disruption of the medial layer of the aortic wall. The accurate diagnosis of an AAS is often made at operation. This manuscript will attempt to clarify the similarities and differences between AD, IMH and PAU of the ascending aorta and describe the challenges in distinguishing them from one another. PMID:27386405

  20. Size, but not experience, affects the ontogeny of constriction performance in ball pythons (Python regius).

    PubMed

    Penning, David A; Dartez, Schuyler F

    2016-03-01

    Constriction is a prey-immobilization technique used by many snakes and is hypothesized to have been important to the evolution and diversification of snakes. However, very few studies have examined the factors that affect constriction performance. We investigated constriction performance in ball pythons (Python regius) by evaluating how peak constriction pressure is affected by snake size, sex, and experience. In one experiment, we tested the ontogenetic scaling of constriction performance and found that snake diameter was the only significant factor determining peak constriction pressure. The number of loops applied in a coil and its interaction with snake diameter did not significantly affect constriction performance. Constriction performance in ball pythons scaled differently than in other snakes that have been studied, and medium to large ball pythons are capable of exerting significantly higher pressures than those shown to cause circulatory arrest in prey. In a second experiment, we tested the effects of experience on constriction performance in hatchling ball pythons over 10 feeding events. By allowing snakes in one test group to gain constriction experience, and manually feeding snakes under sedation in another test group, we showed that experience did not affect constriction performance. During their final (10th) feedings, all pythons constricted similarly and with sufficiently high pressures to kill prey rapidly. At the end of the 10 feeding trials, snakes that were allowed to constrict were significantly smaller than their non-constricting counterparts.

  1. Frequency domain analysis of spreading-constriction thermal impedance

    NASA Astrophysics Data System (ADS)

    Casalegno, Francesco; De Marchi, Andrea; Giaretto, Valter

    2013-02-01

    Spreading-constriction effects are analyzed in the frequency domain. The existence of a half-pole altering the steady state solution at high frequencies is pointed out. Application to the case of thermoelectric devices allows direct comparison with experimental data because thermal quantities can be measured as electrical signals at the very spot where spreading takes place. Good agreement with theory is shown here for a thermoelectric device in which the particular constriction geometry enhances its effect, making easily observable the difference between frequency domain and the steady state approaches.

  2. Frequency domain analysis of spreading-constriction thermal impedance.

    PubMed

    Casalegno, Francesco; De Marchi, Andrea; Giaretto, Valter

    2013-02-01

    Spreading-constriction effects are analyzed in the frequency domain. The existence of a half-pole altering the steady state solution at high frequencies is pointed out. Application to the case of thermoelectric devices allows direct comparison with experimental data because thermal quantities can be measured as electrical signals at the very spot where spreading takes place. Good agreement with theory is shown here for a thermoelectric device in which the particular constriction geometry enhances its effect, making easily observable the difference between frequency domain and the steady state approaches.

  3. Effects of aortic irregularities on blood flow.

    PubMed

    Prahl Wittberg, Lisa; van Wyk, Stevin; Fuchs, Laszlo; Gutmark, Ephraim; Backeljauw, Philippe; Gutmark-Little, Iris

    2016-04-01

    Anatomic aortic anomalies are seen in many medical conditions and are known to cause disturbances in blood flow. Turner syndrome (TS) is a genetic disorder occurring only in females where cardiovascular anomalies, particularly of the aorta, are frequently encountered. In this study, numerical simulations are applied to investigate the flow characteristics in four TS patient- related aortic arches (a normal geometry, dilatation, coarctation and elongation of the transverse aorta). The Quemada viscosity model was applied to account for the non-Newtonian behavior of blood. The blood is treated as a mixture consisting of water and red blood cells (RBC) where the RBCs are modeled as a convected scalar. The results show clear geometry effects where the flow structures and RBC distribution are significantly different between the aortas. Transitional flow is observed as a jet is formed due to a constriction in the descending aorta for the coarctation case. RBC dilution is found to vary between the aortas, influencing the WSS. Moreover, the local variations in RBC volume fraction may induce large viscosity variations, stressing the importance of accounting for the non-Newtonian effects. PMID:26104133

  4. Constrictive pericarditis following open-heart surgery in a child

    PubMed Central

    Deepti, Siddharthan; Gupta, Saurabh Kumar; Ramakrishnan, Sivasubramanian; Talwar, Sachin; Kothari, Shyam Sunder

    2016-01-01

    A 6-year- old child developed constrictive pericarditis 2 years after undergoing an open-heart surgery for a congenital cardiac disorder. No other cause of pericarditis was identified. The clinical condition improved after pericardiectomy. The case is reported for its rarity. PMID:27011697

  5. Shooting quasiparticles from Andreev bound states in a superconducting constriction

    SciTech Connect

    Riwar, R.-P.; Houzet, M.; Meyer, J. S.; Nazarov, Y. V.

    2014-12-15

    A few-channel superconducting constriction provides a set of discrete Andreev bound states that may be populated with quasiparticles. Motivated by recent experimental research, we study the processes in an a.c. driven constriction whereby a quasiparticle is promoted to the delocalized states outside the superconducting gap and flies away. We distinguish two processes of this kind. In the process of ionization, a quasiparticle present in the Andreev bound state is transferred to the delocalized states leaving the constriction. The refill process involves two quasiparticles: one flies away while another one appears in the Andreev bound state. We notice an interesting asymmetry of these processes. The electron-like quasiparticles are predominantly emitted to one side of the constriction while the hole-like ones are emitted to the other side. This produces a charge imbalance of accumulated quasiparticles, that is opposite on opposite sides of the junction. The imbalance may be detected with a tunnel contact to a normal metal lead.

  6. COGNITIVE CONSTRICTION IN AGING AND ATTITUDES TOWARD INTERNATIONAL ISSUES.

    ERIC Educational Resources Information Center

    BACK, KURT W.; GERGEN, KENNETH J.

    THE MAJOR FOCUS OF THIS STUDY WAS THE RELATIONSHIP BETWEEN CONSTRICTION OF TIME PERSPECTIVE AND PREFERENCES FOR CERTAIN TYPES OF SOLUTIONS TO PROBLEMS OF INTERNATIONAL, NATIONAL, AND LOCAL AFFAIRS. THREE GROUPS WERE FORMED ACCORDING TO AGE--UNDER 40, 40-59, AND 60 AND OVER. TABLES SHOW, IN PERCENTAGES, THE RESPONSES TO SUCH QUESTIONS AS WHAT THE…

  7. Theoretical study on the constricted flow phenomena in arteries

    NASA Astrophysics Data System (ADS)

    Sen, S.; Chakravarty, S.

    2012-12-01

    The present study is dealt with the constricted flow characteristics of blood in arteries by making use of an appropriate mathematical model. The constricted artery experiences the generated wall shear stress due to flow disturbances in the presence of constriction. The disturbed flow in the stenosed arterial segment causes malfunction of the cardiovascular system leading to serious health problems in the form of heart attack and stroke. The flowing blood contained in the stenosed artery is considered to be non-Newtonian while the flow is treated to be two-dimensional. The present pursuit also accounts for the motion of the arterial wall and its effect on local fluid mechanics. The flow analysis applies the time-dependent, two-dimensional incompressible nonlinear Navier-Stokes equations for non-Newtonian fluid representing blood. An extensive quantitative analysis presented at the end of the paper based on large scale numerical computations of the quantities of major physiological significance enables one to estimate the constricted flow characteristics in the arterial system under consideration which deviates significantly from that of normal physiological flow conditions.

  8. [Severe disseminated constrictive polyserositis in a patient with rheumatoid arthritis].

    PubMed

    Blagova, O V; Tsaregorodtsev, D A; Nedostup, A V; Maevskaia, I V; Petukhova, N V; Troitskaia, M P; Shadaniia, Ia R

    2010-01-01

    Constrictive polyserositis (pleuritis, pericarditis) is a syndrome within the underlying disease (tuberculosis, periodic disease, rheumatoid arthritis, systemic lupus erythematosus, asbestos, silicosis, uremia, some genetic diseases), a complication due to chest surgery or radiation or drug therapy, is occasionally idiopathic (fibrosing mediastinitis). There are frequently great difficulties in making its nosological diagnosis. The paper describes a patient in whom the onset of disease was exudative pleurisy with the signs of constriction, arthralgias; pleural punctures provided serous exudates with 80% lymphocytes. A year later there was ascitis and shin and foot edemas, which concurrent with hepatomegaly and cholestasis was regarded as cryptogenic liver cirrhosis. The signs of constrictive pericarditis were further revealed. The disease was complicated by the development of pulmonary artery thromboembolism (PATE) (which required the use of warfarin) and hemorrhagic vasculitis. Therapy with metipred in combination with isoniazid yielded a slight effect. The diagnoses of tuberculosis, liver cirrhosis, and autoimmune hepatitis, systemic vasculitis were consecutively rejected; the diagnosis of rheumatoid polyarthritis with systemic manifestations was made, by taking into account persistent arthalgias with the minimum signs of arthritis, noticeably increased C-reactive protein, rheumatoid factor, and cyclic citrullinated peptide antibodies (CCPA); plasmapheresis, therapy with metipred and methotrexate, and subtotal pericardectomy were performed. Constrictive polyserositis concurrent with PATE, hemorrhagic vasculitis (probably, drug-induced one), and hepatic lesion has been first described in a CCPA-positive patient with rheumatoid arthritis in the presence of moderate true arthritis (during steroid therapy).

  9. Apical constriction and epithelial invagination are regulated by BMP activity

    PubMed Central

    Jidigam, Vijay K.; Srinivasan, Raghuraman C.; Patthey, Cedric; Gunhaga, Lena

    2015-01-01

    ABSTRACT Epithelial invagination is a morphological process in which flat cell sheets transform into three-dimensional structures through bending of the tissue. It is accompanied by apical constriction, in which the apical cell surface is reduced in relation to the basal cell surface. Although much is known about the intra-cellular molecular machinery driving apical constriction and epithelial invagination, information of how extra-cellular signals affect these processes remains insufficient. In this study we have established several in vivo assays of placodal invagination to explore whether the external signal BMP regulates processes connected to epithelial invagination. By inhibiting BMP activity in prospective cranial placodes, we provide evidence that BMP signals are required for RhoA and F-actin rearrangements, apical constriction, cell elongation and epithelial invagination. The failure of placode invagination after BMP inhibition appears to be a direct consequence of disrupted apical accumulation of RhoA and F-actin, rather than changes in cell death or proliferation. In addition, our results show that epithelial invagination and acquisition of placode-specific identities are two distinct and separable developmental processes. In summary, our results provide evidence that BMP signals promote epithelial invagination by acting upstream of the intracellular molecular machinery that drives apical constriction and cell elongation. PMID:26621830

  10. Conservative Management of Chronic Aortic Dissection with Underlying Aortic Aneurysm

    PubMed Central

    Yusuf Beebeejaun, Mohammad; Malec, Aleksandra; Gupta, Ravi

    2013-01-01

    Aortic dissection is one of the most common aortic emergencies affecting around 2000 Americans each year. It usually presents in the acute state but in a small percentage of patients aortic dissections go unnoticed and these patients survive without any adequate therapy. With recent advances in medical care and diagnostic technologies, aortic dissection can be successfully managed through surgical or medical options, consequently increasing the related survival rate. However, little is known about the optimal long-term management of patients suffering from chronic aortic dissection. The purpose of the present report is to review aortic dissection, namely its pathology and the current diagnostic tools available, and to discuss the management options for chronic aortic dissection. We report a patient in which chronic aortic dissection presented with recurring episodes of vomiting and also discuss the management plan of our patient who had a chronic aortic dissection as well as an underlying aortic aneurysm. PMID:24179638

  11. Annular management during aortic valve repair: a systematic review.

    PubMed

    Kunihara, Takashi

    2016-02-01

    Annuloplasty is considered to play a key role to control aortic valve regurgitation (AR) and prevent recurrence of AR after aortic valve repair, because aortic root dilatation has emerged as a risk factor for recurrence of AR. Various modifications of annuloplasty have been advocated, however, none of them has become standardized. Thus in this review they are outlined and classified (internal/external, with/without ring, rigid/flexible ring), and their advantages and disadvantages are clarified. Their clinical outcomes seem currently acceptable in general, and external flexible annuloplasty has been performed more frequently with favorable outcomes. However, they are still performed for a minority of patients by special experienced teams with limited follow-up periods. Therefore, it seems too early to determine the superiority or inferiority of each approach. We must carefully conduct evaluation to clarify which approach will become reproducible, effective, and standardized.

  12. Sutureless aortic valve replacement

    PubMed Central

    Phan, Kevin

    2015-01-01

    The increasing incidence of aortic stenosis and greater co-morbidities and risk profiles of the contemporary patient population has driven the development of minimally invasive aortic valve surgery and percutaneous transcatheter aortic valve implantation (TAVI) techniques to reduce surgical trauma. Recent technological developments have led to an alternative minimally invasive option which avoids the placement and tying of sutures, known as “sutureless” or rapid deployment aortic valves. Potential advantages for sutureless aortic prostheses include reducing cross-clamp and cardiopulmonary bypass (CPB) duration, facilitating minimally invasive surgery and complex cardiac interventions, whilst maintaining satisfactory hemodynamic outcomes and low paravalvular leak rates. However, given its recent developments, the majority of evidence regarding sutureless aortic valve replacement (SU-AVR) is limited to observational studies and there is a paucity of adequately-powered randomized studies. Recently, the International Valvular Surgery Study Group (IVSSG) has formulated to conduct the Sutureless Projects, set to be the largest international collaborative group to investigate this technology. This keynote lecture will overview the use, the potential advantages, the caveats, and current evidence of sutureless and rapid deployment aortic valve replacement (AVR). PMID:25870807

  13. Abdominal aortic aneurysm.

    PubMed

    Keisler, Brian; Carter, Chuck

    2015-04-15

    Abdominal aortic aneurysm refers to abdominal aortic dilation of 3.0 cm or greater. The main risk factors are age older than 65 years, male sex, and smoking history. Other risk factors include a family history of abdominal aortic aneurysm, coronary artery disease, hypertension, peripheral artery disease, and previous myocardial infarction. Diagnosis may be made by physical examination, an incidental finding on imaging, or ultrasonography. The U.S. Preventive Services Task Force released updated recommendations for abdominal aortic aneurysm screening in 2014. Men 65 to 75 years of age with a history of smoking should undergo one-time screening with ultrasonography based on evidence that screening will improve abdominal aortic aneurysm-related mortality in this population. Men in this age group without a history of smoking may benefit if they have other risk factors (e.g., family history of abdominal aortic aneurysm, other vascular aneurysms, coronary artery disease). There is inconclusive evidence to recommend screening for abdominal aortic aneurysm in women 65 to 75 years of age with a smoking history. Women without a smoking history should not undergo screening because the harms likely outweigh the benefits. Persons who have a stable abdominal aortic aneurysm should undergo regular surveillance or operative intervention depending on aneurysm size. Surgical intervention by open or endovascular repair is the primary option and is typically reserved for aneurysms 5.5 cm in diameter or greater. There are limited options for medical treatment beyond risk factor modification. Ruptured abdominal aortic aneurysm is a medical emergency presenting with hypotension, shooting abdominal or back pain, and a pulsatile abdominal mass. It is associated with high prehospitalization mortality. Emergent surgical intervention is indicated for a rupture but has a high operative mortality rate. PMID:25884861

  14. Planetary rings

    SciTech Connect

    Greenberg, R.; Brahic, A.

    1984-01-01

    Among the topics discussed are the development history of planetary ring research, the view of planetary rings in astronomy and cosmology over the period 1600-1900, the characteristics of the ring systems of Saturn and Uranus, the ethereal rings of Jupiter and Saturn, dust-magnetosphere interactions, the effects of radiation forces on dust particles, the collisional interactions and physical nature of ring particles, transport effects due to particle erosion mechanisms, and collision-induced transport processes in planetary rings. Also discussed are planetary ring waves, ring particle dynamics in resonances, the dynamics of narrow rings, the origin and evolution of planetary rings, the solar nebula and planetary disk, future studies of the planetary rings by space probes, ground-based observatories and earth-orbiting satellites, and unsolved problems in planetary ring dynamics.

  15. Expansion of Severely Constricted Visual Field Using Google Glass.

    PubMed

    Trese, Matthew G J; Khan, Naheed W; Branham, Kari; Conroy, Erin Brown; Moroi, Sayoko E

    2016-05-01

    Google Glass (Google, Mountain View, CA) is a wearable technology with a computer and camera mounted on an eyeglass frame. The camera captures wide-angle video and projects it onto a prism located in the right superior temporal quadrant of the wearer's visual field. The authors present a case of an individual who used Google Glass' video projection feature to expand his severely constricted right visual field. This patient reported improved ambulatory navigation. Using Google Glass, the patient's peripheral vision, measured using Goldmann kinetic perimetry, expanded impressively. Based on these preliminary results, the authors propose further characterization on the potential utility of such head-mount display technology as a tool to improve the lives of patients with severely constricted visual fields. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:486-489.].

  16. [TUBERCULOUS CONSTRICTIVE PERICARDITIS DETECTED ON POSITRON EMISSION TOMOGRAPHY].

    PubMed

    Takakura, Hiroki; Sunada, Kouichi; Shimizu, Kunihiko

    2016-02-01

    A 72-year-old man presented with fever, dyspnea, and weight loss. He was referred to our hospital for further examination of the cause of the pleural effusions. Chest computed tomography showed pleural effusions, a pericardial effusion, and enlarged lymph nodes in the carina tracheae. We administered treatment for heart failure and conducted analyses for a malignant tumor. The pericardial effusion improved, but the pericardium was thickened. Positron emission tomography-computed tomography (PET-CT) showed fluorine-18 deoxyglucose accumulation at the superior fovea of the right clavicle, carina tracheae, superior mediastinum lymph nodes, and a thickened pericardium. Because these findings did not suggest malignancy, we assumed this was a tuberculous lesion. Echocardiography confirmed this finding as constrictive pericarditis; therefore, pericardiolysis was performed. Pathological examination showed features of caseous necrosis and granulomatous changes. Hence, the patient was diagnosed with tuberculous constrictive pericarditis. PET-CT serves as a useful tool for the diagnosis of tuberculous pericarditis. PMID:27263228

  17. Automated control of linear constricted plasma source array

    DOEpatents

    Anders, Andre; Maschwitz, Peter A.

    2000-01-01

    An apparatus and method for controlling an array of constricted glow discharge chambers are disclosed. More particularly a linear array of constricted glow plasma sources whose polarity and geometry are set so that the contamination and energy of the ions discharged from the sources are minimized. The several sources can be mounted in parallel and in series to provide a sustained ultra low source of ions in a plasma with contamination below practical detection limits. The quality of film along deposition "tracks" opposite the plasma sources can be measured and compared to desired absolute or relative values by optical and/or electrical sensors. Plasma quality can then be adjusted by adjusting the power current values, gas feed pressure/flow, gas mixtures or a combination of some or all of these to improve the match between the measured values and the desired values.

  18. Experimental folding and boudinage under pure constrictional conditions

    NASA Astrophysics Data System (ADS)

    Kobberger, Gustav

    1995-07-01

    Constrictional folds are characterized by true fold-axis parallel extension if the rock-volume does not vary during deformation. Studies of such folds in experiments, using plasticine layers of different apparent viscosity and power-law exponent, clearly indicate that fold-axis parallel stretch may be accompanied by plastic elongation as well as boudinage of the competent layer. Characteristic aspects of the experimentally folded competent layers are: (1) coeval development of folds and boudins; (2) layer thickness not changing during deformation; (3) layer-parallel shortening in sections perpendicular to the fold (stretching) axis; (4) enlargement of the initial thickness of the competent layer results in increasing fold wavelength and decreasing number of boudins. The ratio of dominant wavelength to layer thickness of the constrictional folds can be described mathematically approximately by the equation developed for plane strain folding of power-law materials

  19. Right Aortic Arch and Coarctation: A Rare Association

    PubMed Central

    Ismat, Fraz A.; Weinberg, Paul M.; Rychik, Jack; Karl, Tom R.; Fogel, Mark A.

    2006-01-01

    Objectives Understand anatomical and clinical correlatives to coarctation in right aortic arch. Background Coarctation of the aorta is rare in patients with a functional right aortic arch. We reviewed a single institutional experience, examining associated diagnoses, diagnostic methodology, and surgical approaches. Methods A retrospective study was performed of our echocardiographic, magnetic resonance imaging, catheterization, and surgical databases from 1988 to 2001. Results Of 240 patients with right aortic arch, 10 (4.1%) had coarctation, constituting 1.9% of all native coarctations (n = 524). Nine (90%) had long-segment hypoplasia. Six (60%) had an aberrant left subclavian artery or retroesophageal diverticulum, 3 (30%) had mirror image branching, and 1 (10%) had a double arch with an atretic left arch. Other congenital heart defects were seen in 6 (60%) comprising 3 with ventricular septal defects, and one each with double-outlet right ventricle, cor triatriatum, and pulmonary valve abnormality. No patients with long-segment hypoplasia had bicuspid aortic valve. Six (60%) had vascular rings, and 5 (50%) had other associated syndromes. Magnetic resonance imaging and/or echocardiography successfully diagnosed all of these patients. Although long-segment right aortic arch coarctation courses behind the trachea posteriorly, only 2 needed an extra-anatomic (jump) graft; the remainders were repaired with patch angioplasty. Conclusion Coarctation with right aortic arch is rare, constituting 4.1% of all patients with right aortic arch, compared with 5–8% of patients with left aortic arch and congenital heart disease. Nearly all had long-segment hypoplasia without bicuspid aortic valve, and half were part of other syndrome complexes. This association can be diagnosed noninvasively and can often be repaired by patch angioplasty. PMID:17330153

  20. Properties of a constricted-tube air-flow levitator

    NASA Technical Reports Server (NTRS)

    Rush, J. E.; Stephens, W. K.; Ethridge, E. C.

    1982-01-01

    The properties of a constricted-tube gas flow levitator first developed by Berge et al. (1981) have been investigated experimentally in order to predict its behavior in a gravity-free environment and at elevated temperatures. The levitator consists of a constricted (quartz) tube fed at one end by a source of heated air or gas. A spherical sample is positioned by the air stream on the downstream side of the constriction, where it can be melted and resolidified without touching the tube. It is shown experimentally that the kinematic viscosity is the important fluid parameter for operation in thermal equilibrium at high temperatures. If air is heated from room temperature to 1200 C, the kinematic viscosity increases by a factor of 14. To maintain a given value of the Reynolds number, the flow rate would have to be increased by the same factor for a specific geometry of tube and sample. Thus, to maintain stable equilibrium, the flow rate should be increased as the air or other gas is heated. The other stability problem discussed is associated with changes in the shape of a cylindrical sample as it melts.

  1. Size quantization of Dirac fermions in graphene constrictions

    PubMed Central

    Terrés, B.; Chizhova, L. A.; Libisch, F.; Peiro, J.; Jörger, D.; Engels, S.; Girschik, A.; Watanabe, K.; Taniguchi, T.; Rotkin, S. V.; Burgdörfer, J.; Stampfer, C.

    2016-01-01

    Quantum point contacts are cornerstones of mesoscopic physics and central building blocks for quantum electronics. Although the Fermi wavelength in high-quality bulk graphene can be tuned up to hundreds of nanometres, the observation of quantum confinement of Dirac electrons in nanostructured graphene has proven surprisingly challenging. Here we show ballistic transport and quantized conductance of size-confined Dirac fermions in lithographically defined graphene constrictions. At high carrier densities, the observed conductance agrees excellently with the Landauer theory of ballistic transport without any adjustable parameter. Experimental data and simulations for the evolution of the conductance with magnetic field unambiguously confirm the identification of size quantization in the constriction. Close to the charge neutrality point, bias voltage spectroscopy reveals a renormalized Fermi velocity of ∼1.5 × 106 m s−1 in our constrictions. Moreover, at low carrier density transport measurements allow probing the density of localized states at edges, thus offering a unique handle on edge physics in graphene devices. PMID:27198961

  2. Transient dynamics of an elastic capsule in a microfluidic constriction

    PubMed Central

    Park, Sun-Young; Dimitrakopoulos, P.

    2013-01-01

    In this paper we investigate computationally the transient dynamics of an elastic capsule flowing in a square microchannel with a rectangular constriction, and compare it with that of a droplet. The confinement and expansion dynamics of the fluid flow results in a rich deformation behavior for the capsule, from an elongated shape at the constriction entrance, to a flattened parachute shape at its exit. Larger capsules are shown to take more time to pass the constriction and cause higher additional pressure difference, owing to higher flow blocking. Our work highlights the effects of two different mechanisms for non-tank-treading transient capsule dynamics. The capsule deformation results from the combined effects of the surrounding and inner fluids’ normal stresses on the soft particle’s interface, and thus when the capsule viscosity increases, its transient deformation decreases, as for droplets. However, the capsule deformation is not able to create a strong enough inner circulation (owing to restrictions imposed by the material membrane), and thus the viscosity ratio does not affect much the capsule velocity and the additional pressure difference. In addition, the weak inner circulation results in a positive additional pressure difference ΔP+ even for low-viscosity capsules, in direct contrast to low-viscosity droplets which create a negative ΔP+. Our findings suggest that the high cytoplasmatic viscosity, owing to the protein hemoglobin required for oxygen transport, does not affect adversely the motion of non-tank-trading erythrocytes in vascular capillaries. PMID:24223621

  3. Role of calcium in the constriction of isolated cerebral arteries

    SciTech Connect

    Wendling, W.W.

    1987-01-01

    Calcium entry blockers (CEB) have been used in the experimental treatment or prevention of many cerebrovascular disorders including stroke, post-ischemic hypoperfusion after cardiac arrest, cerebral vasospasm after subarachnoid hemorrhage, and migraine headache. However, the mechanism of action of these drugs on the cerebral circulation is poorly understood. This study examined the effects of calcium antagonists, Ca/sup 2 +/-deficient solutions, and vasocostrictors on cerebrovascular tone and /sup 45/Ca fluxes, to determine the role of calcium in cerebral arterial constriction. A Scatchard plot of /sup 45/Ca binding to BMCA showed that Ca/sup 2 +/ was bound at either low or high affinity binding sties. The four vasoconstrictors (potassium, serotonin, PGF/sub 2 ..cap alpha../, or SQ-26,655) each increased low affinity /sup 45/Ca uptake into BMCA. The results demonstrate that: (1) Potassium and serotonin constrict BMCA mainly by promoting Ca/sup 2 +/ influx through CEB-sensitive channels; (2) PGF/sub 2 ..cap alpha../ and SQ-26,655 constrict BMCA in part by promoting Ca/sup 2 +/ influx through CEB-sensitive channels, and in part by releasing Ca/sup 2 +/ from depletable internal stores; (3) The major action of CEB on BMCA is to block vasoconstrictor-induced Ca/sup 2 +/ uptake through both potential-operated (K/sup +/-stimulated) and receptor-operated channels.

  4. Characterization of superconducting nanowire single-photon detector with artificial constrictions

    SciTech Connect

    Zhang, Ling; Liu, Dengkuan; Wu, Junjie; He, Yuhao; Lv, Chaolin; You, Lixing Zhang, Weijun; Zhang, Lu; Liu, Xiaoyu; Wang, Zhen Xie, Xiaoming

    2014-06-15

    Statistical studies on the performance of different superconducting nanowire single-photon detectors (SNSPDs) on one chip suggested that random constrictions existed in the nanowire that were barely registered by scanning electron microscopy. With the aid of advanced e-beam lithography, artificial geometric constrictions were fabricated on SNSPDs as well as single nanowires. In this way, we studied the influence of artificial constrictions on SNSPDs in a straight forward manner. By introducing artificial constrictions with different wire widths in single nanowires, we concluded that the dark counts of SNSPDs originate from a single constriction. Further introducing artificial constrictions in SNSPDs, we studied the relationship between detection efficiency and kinetic inductance and the bias current, confirming the hypothesis that constrictions exist in SNSPDs.

  5. Transcatheter aortic valve implantation.

    PubMed

    Kapadia, Samir R; Tuzcu, E Murat

    2009-12-01

    Aortic stenosis is the most important valvular heart disease affecting the elderly population. Surgical aortic valve replacement is the mainstay of treatment, although a substantial number of patients are considered high risk for surgery. Many of these patients do not undergo surgery and have poor outcomes from medically treated symptomatic, severe aortic stenosis. Transcatheter aortic valve implantation (TAVI) provides a promising treatment option for some of these patients. Several devices are under investigation. The Edwards Sapien valve (Edwards Lifesciences, Irvine, CA) and the CoreValve (Medtronic, Minneapolis, MN) have the largest human experience to date. Initial data suggest that these devices have an acceptable safety profile and provide excellent hemodynamic relief of aortic stenosis. The Edwards Sapien valve is currently under investigation in the United States in the PARTNER (Placement of Aortic Transcatheter Valve) trial in high-risk surgical or inoperable patients; TAVI is available for clinical use in both Canada and Europe. TAVI is not used in low- or intermediate-risk surgical patients; however, future studies may prove its applicability in these subsets. The major complications of TAVI include access site-related problems and device malpositioning/migration. There are several new-generation prosthetic valves and delivery systems designed to be low profile and repositionable. Technical advances and refinement of the implantation methods may make TAVI even safer and ultimately a better treatment option, not only for patients with high surgical risk but also for those with moderate or low risk.

  6. [Inflammatory abdominal aortic aneurysm].

    PubMed

    Ziaja, K; Sedlak, L; Urbanek, T; Kostyra, J; Ludyga, T

    2000-01-01

    The reported incidence of inflammatory abdominal aortic aneurysm (IAAA) is from 2% to 14% of patients with abdominal aortic aneurysm and the etiology of this disease is still discussed--according to the literature several pathogenic theories have been proposed. From 1992 to 1997 32 patients with IAAA were operated on. The patients were mostly symptomatic--abdominal pain was present in 68.75% cases, back pain in 31.25%, fever in 12.5% and weight loss in 6.25% of the operated patients. In all the patients ultrasound examination was performed, in 4 patients CT and in 3 cases urography. All the patients were operated on and characteristic signs of inflammatory abdominal aortic aneurysm like: thickened aortic wall, perianeurysmal infiltration or retroperitoneal fibrosis with involvement of retroperitoneal structures were found. In all cases surgery was performed using transperitoneal approach; in three cases intraoperatively contiguous abdominal organs were injured, which was connected with their involvement into periaortic inflammation. In 4 cases clamping of the aorta was done at the level of the diaphragmatic hiatus. 3 patients (9.37%) died (one patient with ruptured abdominal aortic aneurysm). Authors present diagnostic procedures and the differences in the surgical tactic, emphasizing the necessity of the surgical therapy in patients with inflammatory abdominal aortic aneurysm.

  7. Are Aortic Stent Grafts Safe in Pregnancy?

    PubMed Central

    Khandanpour, Nader; Mehta, Tapan A.; Adiseshiah, M.; Meyer, Felicity J.

    2015-01-01

    Aortic stent grafts are increasingly used to treat aortic aneurysms and also other aortic pathologies. The safety of aortic stent grafts in pregnancy has never been studied or reported. We report on two cases of aortic stent grafts in pregnant women and discuss the effect of pregnancy on these aortic stent grafts. PMID:26229702

  8. Reoperative transapical transcatheter aortic valve replacement for central aortic regurgitation.

    PubMed

    Zhu, Yuanjia; Kapadia, Samir; Krishnaswamy, Amar; Svensson, Lars G; Mick, Stephanie

    2016-09-01

    Paravalvular leak-related aortic regurgitation after transcatheter aortic valve replacement (TAVR) is a common complication and is associated with increased short- and long-term mortality. However, the impact of isolated central aortic regurgitation is unknown. We report a case of transapical (TA) TAVR with postprocedural central aortic regurgitation, who returned after two years with progression of regurgitation. A reoperative valve-in-valve TA-TAVR was performed. PMID:27405799

  9. Surgical Aortic Valvuloplasty Versus Balloon Aortic Valve Dilatation in Children.

    PubMed

    Donald, Julia S; Konstantinov, Igor E

    2016-09-01

    Balloon aortic valve dilatation (BAD : is assumed to provide the same outcomes as surgical aortic valvuloplasty (SAV). However, the development of precise modern surgical valvuloplasty techniques may result in better long-term durability of the aortic valve repair. This review of the recent literature suggests that current SAV provides a safe and durable repair. Furthermore, primary SAV appears to have greater freedom from reintervention and aortic valve replacement when compared to BAD. PMID:27587493

  10. Screening for Abdominal Aortic Aneurysm

    MedlinePlus

    Understanding Task Force Recommendations Screening for Abdominal Aortic Aneurysm The U.S. Preventive Services Task Force (Task Force) ... final recommendation statement on Screening for Abdominal Aortic Aneurysm. This final recommendation statement applies to adults ages ...

  11. Aneurysms: thoracic aortic aneurysms.

    PubMed

    Chun, Kevin C; Lee, Eugene S

    2015-04-01

    Thoracic aortic aneurysms (TAAs) have many possible etiologies, including congenital heart defects (eg, bicuspid aortic valves, coarctation of the aorta), inherited connective tissue disorders (eg, Marfan, Ehlers-Danlos, Loeys-Dietz syndromes), and degenerative conditions (eg, medial necrosis, atherosclerosis of the aortic wall). Symptoms of rupture include a severe tearing pain in the chest, back, or neck, sometimes associated with cardiovascular collapse. Before rupture, TAAs may exert pressure on other thoracic structures, leading to a variety of symptoms. However, most TAAs are asymptomatic and are found incidentally during imaging for other conditions. Diagnosis is confirmed with computed tomography scan or echocardiography. Asymptomatic TAAs should be monitored with imaging at specified intervals and patients referred for repair if the TAAs are enlarging rapidly (greater than 0.5 cm in diameter over 6 months for heritable etiologies; greater than 0.5 cm over 1 year for degenerative etiologies) or reach a critical aortic diameter threshold for elective surgery (5.5 cm for TAAs due to degenerative etiologies, 5.0 cm when associated with inherited syndromes). Open surgery is used most often to treat asymptomatic TAAs in the ascending aorta and aortic arch. Asymptomatic TAAs in the descending aorta often are treated medically with aggressive blood pressure control, though recent data suggest that endovascular procedures may result in better long-term survival rates. PMID:25860136

  12. [Thoracoabdominal aortic aneurysm].

    PubMed

    Kalder, J; Kotelis, D; Jacobs, M J

    2016-09-01

    Thoracoabdominal aortic aneurysms (TAAA) are rare events with an incidence of 5.9 cases per 100,000 persons per year. In Germany approximately 940 TAAA procedures are performed annually. The cause of TAAA is mostly degenerative but they can also occur on the basis of an aortic dissection or connective tissue disease (e. g. Marfan's syndrome). Patients often have severe comorbidities and suffer from hypertension, coronary heart disease or chronic obstructive pulmonary disease, mostly as a result of smoking. Operative treatment is indicated when the maximum aortic diameter has reached 6 cm (> 5 cm in patients with connective tissue disease) or the aortic diameter rapidly increases (> 5 mm/year). Treatment options are open surgical aortic repair with extracorporeal circulation, endovascular repair with branched/fenestrated endografts and parallel grafts (chimneys) or a combination of open and endovascular procedures (hybrid procedures). Mortality rates after both open and endovascular procedures are approximately 8 % depending on the extent of the repair. Furthermore, there are relevant risks of complications, such as paraplegia (up to 20 %) and the necessity for dialysis. In recent years several approaches to minimize these risks have been proposed. Besides cardiopulmonary risk evaluation, clinical assessment of patients by the physician with respect to the patient-specific anatomy influences the allocation of patients to one treatment option or another. Surgery of TAAA should ideally be performed in high-volume centers in order to achieve better results. PMID:27558261

  13. Quadricuspid aortic valves.

    PubMed

    Timperley, Jonathan; Milner, Robert; Marshall, Andrew J; Gilbert, Timothy J

    2002-12-01

    Quadricuspid aortic valves (QAV) are a rare but well recognized cause of significant aortic regurgitation. The first case was found reported in 1862. Since then there have been 110 reported cases of QAV and we report 4 more. Previously, these were diagnosed at the time of surgery or postmortem examination. With advances in echocardiography, including harmonic imaging, and also the advent of transesophageal echocardiography, more cases are being diagnosed prior to surgery. We describe four more cases, three diagnosed preoperatively and one at the time of surgery, and then review the previously reported cases. Of the 114 cases reported, 46 had the aortic valve replaced, most commonly in the 5th and 6th decade of life. Hurwitz and Roberts classified quadricuspid valves according to the size of the leaflets. It has previously been believed that QAVs with four equal sized leaflets were less likely to develop significant aortic regurgitation; however, on review of the available cases, this would not appear to be the case. The preoperative diagnosis of QAVs is important as they can be associated with abnormally placed coronary ostium. Of the 114 cases reported, there are 10 reports of abnormally placed ostia. There has been at least one reported case of death occurring because of obstruction of an abnormally placed right coronary ostium by a prosthetic aortic valve.

  14. Awake transapical aortic valve implantation.

    PubMed

    Petridis, Francesco Dimitri; Savini, Carlo; Castelli, Andrea; Di Bartolomeo, Roberto

    2012-05-01

    Transapical aortic valve implantation is being employed as a less invasive alternative to open heart surgery in high-risk patients with severe aortic stenosis. Here we report the case of an awake transapical aortic valve implantation in a patient with severe chronic obstructive pulmonary disease.

  15. Proximal aortic dissection (dissecting aortic aneurysm) in a mature ostrich.

    PubMed

    Ferreras, M C; González, J; Pérez, V; Reyes, L E; Gómez, N; Pérez, C; Corpa, J M; García-Marín, J F

    2001-01-01

    The gross and histopathologic lesions observed in a case of spontaneous proximal aortic dissection (dissecting aortic aneurysm) in a mature ostrich are reported. At necropsy, a dissecting intramural hematoma was seen in the proximal aorta, extended about 12 cm distally from the aortic valves. Histopathologic changes in aortic dissection included fragmentation and disruption of elastic laminae, presence of cystic extracellular spaces, and pooling of ground substance in the tunica media. Hepatic copper levels were measured, and the low concentration found suggested that a copper deficiency together with other risk factors such as the elevation of blood pressure may have been implicated in the development of the aortic dissection seen in this ostrich.

  16. Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Cuzzi, J. N.

    2014-12-01

    The rings are changing before our eyes; structure varies on all timescales and unexpected things have been discovered. Many questions have been answered, but some answers remain elusive (see Cuzzi et al 2010 for a review). Here we highlight the major ring science progress over the mission to date, and describe new observations planned for Cassini's final three years. Ring Composition and particle sizes: The rings are nearly all water ice with no other ices - so why are they reddish? The C Ring and Cassini Division are "dirtier" than the more massive B and A Rings, as shown by near-IR and, recently, microwave observations. Particle sizes, from stellar and radio occultations, vary from place to place. Ring structure, micro and macro: numerous spiral density waves and ubiquitous "self-gravity wakes" reveal processes which fostered planet formation in the solar system and elsewhere. However, big puzzles remain regarding the main ring divisions, the C Ring plateau structures, and the B Ring irregular structure. Moonlets, inside and out, seen and unseen: Two gaps contain sizeable moonlets, but more gaps seem to contain none; even smaller embedded "propeller" objects wander, systematically or randomly, through the A ring. Rubble pile ringmoons just outside the rings may escaped from the rings, and the recently discovered "Peggy" may be trying this as we watch. Impact bombardment of the rings: Comet fragments set the rings to rippling on century-timescales, and boulders crash through hourly; meanwhile, the constant hail of infalling Kuiper belt material has a lower mass flux than previously thought. Origin and Age of the Rings: The ring mass and bombardment play key roles. The ring mass is well known everywhere but in the B Ring (where most of it is). New models suggest how tidal breakup of evolving moons may have formed massive ancient rings, of which the current ring is just a shadow. During its last three years, the Cassini tour profile will allow entirely new

  17. Planetary rings

    NASA Technical Reports Server (NTRS)

    Cook, A. F.

    1980-01-01

    Observations of the Rings of Saturn from the Pioneer spacecraft, discovery of the Ring of Jupiter, ground based polarimetry of the Rings of Saturn and some theoretical studies may be combined to markedly advance our understanding of the Rings of Jupiter, Saturn and Uranus. In particular, narrow rings can be self-gravitatingly stable inside Roche's limit and outside another closer limit. They can be created from a satellite which evolves across its Roche limit either by inward tidal drift or by growth of the planet by accretion. These considerations suggest that Neptune may well be surrounded by one or more narrow rings like those of Uranus.

  18. Transition from positive to negative magnetoresistance induced by a constriction in semiconductor nanowire

    NASA Astrophysics Data System (ADS)

    Wołoszyn, M.; Spisak, B. J.; Wójcik, P.; Adamowski, J.

    2016-09-01

    We have studied the magnetotransport through an indium antimonide (InSb) nanowire grown in [111] direction, with a geometric constriction and in an external magnetic field applied along the nanowire axis. We have found that the magnetoresistance is negative for the narrow constriction, nearly zero for the constriction of some intermediate radius, and takes on positive values for the constriction with the radius approaching that of the nanowire. For all magnitudes of the magnetic field, the radius of constriction at which the change of the magnetoresistance sign takes place has been found to be almost the same as long as other geometric parameters of the nanowire are fixed. The sign reversing of the magnetoresistance is explained as a combined effect of two factors: the influence of the constriction on the transverse states and the spin Zeeman effect.

  19. Transcatheter Aortic Valve Implantation.

    PubMed

    Malaisrie, S Chris; Iddriss, Adam; Flaherty, James D; Churyla, Andrei

    2016-05-01

    Severe aortic stenosis (AS) is a life-threatening condition when left untreated. Aortic valve replacement (AVR) is the gold standard treatment for the majority of patients; however, transcatheter aortic valve implantation/replacement (TAVI/TAVR) has emerged as the preferred treatment for high-risk or inoperable patients. The concept of transcatheter heart valves originated in the 1960s and has evolved into the current Edwards Sapien and Medtronic CoreValve platforms available for clinical use. Complications following TAVI, including cerebrovascular events, perivalvular regurgitation, vascular injury, and heart block have decreased with experience and evolving technology, such that ongoing trials studying TAVI in lower risk patients have become tenable. The multidisciplinary team involving the cardiac surgeon and cardiologist plays an essential role in patient selection, procedural conduct, and perioperative care.

  20. Architecture of the ring formed by the tubulin homologue FtsZ in bacterial cell division

    PubMed Central

    Szwedziak, Piotr; Wang, Qing; Bharat, Tanmay A M; Tsim, Matthew; Löwe, Jan

    2014-01-01

    Membrane constriction is a prerequisite for cell division. The most common membrane constriction system in prokaryotes is based on the tubulin homologue FtsZ, whose filaments in E. coli are anchored to the membrane by FtsA and enable the formation of the Z-ring and divisome. The precise architecture of the FtsZ ring has remained enigmatic. In this study, we report three-dimensional arrangements of FtsZ and FtsA filaments in C. crescentus and E. coli cells and inside constricting liposomes by means of electron cryomicroscopy and cryotomography. In vivo and in vitro, the Z-ring is composed of a small, single-layered band of filaments parallel to the membrane, creating a continuous ring through lateral filament contacts. Visualisation of the in vitro reconstituted constrictions as well as a complete tracing of the helical paths of the filaments with a molecular model favour a mechanism of FtsZ-based membrane constriction that is likely to be accompanied by filament sliding. DOI: http://dx.doi.org/10.7554/eLife.04601.001 PMID:25490152

  1. Endovascular aortic aneurysm operations.

    PubMed

    Najibi, Sasan; Terramani, Thomas T; Weiss, Victor J; Smith, Robert B; Salam, Atef A; Dodson, Thomas F; Chaikof, Elliot L; Lumsden, Alan B

    2002-02-01

    Options for the treatment of abdominal and thoracic aortic aneurysms are in a state of evolutionary change. The development and continued refinement of the endoluminal approaches has decreased the need for open aortic aneurysm surgery. Endovascular stent graft technology is an area of active research in which both the delivery systems and the endografts are undergoing continued improvement so that patients with what was previously thought to be unfavorable anatomy may be treated by these means. The design and deployment techniques of the currently available endografts, as well as those in clinical trials, are presented. PMID:11822962

  2. Neptune's rings

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This 591-second exposure of the rings of Neptune were taken with the clear filter by the Voyager 2 wide-angle camera. The two main rings are clearly visible and appear complete over the region imaged. Also visible in this image is the inner faint ring and the faint band which extends smoothly from the ring roughly halfway between the two bright rings. Both of these newly discovered rings are broad and much fainter than the two narrow rings. The bright glare is due to over-exposure of the crescent on Neptune. Numerous bright stars are evident in the background. Both bright rings have material throughout their entire orbit, and are therefore continuous. The Voyager Mission is conducted by JPL for NASA's Office of Space Science and Applications.

  3. Vascular ring

    MedlinePlus

    ... with aberrant subclavian and left ligamentum ateriosus; Congenital heart defect - vascular ring; Birth defect heart - vascular ring ... accounts for less than 1% of all congenital heart problems. The condition occurs as often in males ...

  4. Mechanical response of red blood cells entering a constriction

    PubMed Central

    Zeng, Nancy F.; Ristenpart, William D.

    2014-01-01

    Most work on the dynamic response of red blood cells (RBCs) to hydrodynamic stress has focused on linear velocity profiles. Relatively little experimental work has examined how individual RBCs respond to pressure driven flow in more complex geometries, such as the flow at the entrance of a capillary. Here, we establish the mechanical behaviors of healthy RBCs undergoing a sudden increase in shear stress at the entrance of a narrow constriction. We pumped RBCs through a constriction in a microfluidic device and used high speed video to visualize and track the flow behavior of more than 4400 RBCs. We show that approximately 85% of RBCs undergo one of four distinct modes of motion: stretching, twisting, tumbling, or rolling. Intriguingly, a plurality of cells (∼30%) exhibited twisting (rotation around the major axis parallel to the flow direction), a mechanical behavior that is not typically observed in linear velocity profiles. We present detailed statistical analyses on the dynamics of each motion and demonstrate that the behavior is highly sensitive to the location of the RBC within the channel. We further demonstrate that the observed tumbling, twisting, and rolling rotations can be rationalized qualitatively in terms of rigid body mechanics. The detailed experimental statistics presented here should serve as a useful resource for modeling of RBC behavior under physiologically important flow conditions. PMID:25553197

  5. Tuberculous constrictive pericarditis complicated with tuberculous mediastinitis - case report.

    PubMed

    Man, Milena Adina; NiŢu, Mimi Floarea; Strâmbu, Lelia; Florescu, Cristina; Streba, Costin Teodor; Trofor, Antigona Carmen

    2016-01-01

    Constrictive pericarditis is a rare and severe disease. A 37-year-old patient was admitted in the hospital for dyspnea, precordial pain, right-sided cardiac failure. Chest X-ray showed cardiac enlargement and an opacity suggestive for pleural effusion. Echocardiography revealed an adhesive-effusive-constrictive pericarditis, a very thickened pericardium and bilateral pleural effusion. After a pericardiectomy done to restore cardiac compensation and to identify etiological factors, a tuberculous pericarditis (TBP) was diagnosed. After surgery and starting anti-TB treatment, the patient presented altered clinical status, dyspnea, dry cough, fever and delayed callus formation at sternum level. Thoracic scan revealed mediastinal air collections, pericarditis and pleurisy. Thus, the TBP diagnosis was extended to mediastinal TB and anti-TB therapy was continued. After four months of treatment, another thoracic scan showed disappearance of the mediastinal air-leakage bubbles, multiple new micronodules in both lungs and lymph nodes of up to 15 mm; also increasing pericardial and pleural effusions. This case was interpreted as a TB treatment failure situation. A retreatment regimen was started, resulting in a slow favorable outcome. Pericardial TB is a rare condition, usually with delayed diagnosis and poor treatment benefits. Whenever possible, earlier diagnostic can contribute to better management of these cases.

  6. Surgical correction of constricted ear combined with Stahl's ear.

    PubMed

    Bi, Ye; Lin, Lin; Yang, Qinhua; Pan, Bo; Zhao, Yanyong; He, Leren; Jiang, Haiyue

    2015-07-01

    Constricted ear combined with Stahl's ear is a rare ear deformity, which is a kind of complex congenital auricular deformity. From 1 January 2007 to 1 January 2014, 19 patients with constricted ear combined with Stahl's ear (Spock ear) were enrolled in this study, most of which were unilaterally deformed. To correct the deformity, a double Z-shaped skin incision was made on the posterior side of the auricle, with the entire layer of cartilage cut parallel to the helix traversing the third crus to form a fan-shaped cartilage flap. The superior crura of the antihelix were shaped by the folding cartilage rim. The cartilage of the abnormal third crus was made part of the new superior crura of antihelix, and the third crus was eliminated. The postoperative aesthetic assessment of the reshaped auricle was graded by both doctors and patients (or their parents). Out of the 19 patients, the number of satisfying cases of the symmetry, helix stretch, elimination of the third crus, the cranioauricular angle, and the substructure of the reshaped ears was 14 (nine excellent and five good), 16 (six excellent and 10 good), 17 (eight excellent and nine good), 15 (five excellent and 10 good), and 13 (two excellent and 11 good), respectively. With a maximum of a 90-month follow-up, no complication was observed. The results of the study suggested that this rare deformity could be corrected by appropriate surgical treatment, with a satisfied postoperative appearance.

  7. Tuberculous constrictive pericarditis complicated with tuberculous mediastinitis - case report.

    PubMed

    Man, Milena Adina; NiŢu, Mimi Floarea; Strâmbu, Lelia; Florescu, Cristina; Streba, Costin Teodor; Trofor, Antigona Carmen

    2016-01-01

    Constrictive pericarditis is a rare and severe disease. A 37-year-old patient was admitted in the hospital for dyspnea, precordial pain, right-sided cardiac failure. Chest X-ray showed cardiac enlargement and an opacity suggestive for pleural effusion. Echocardiography revealed an adhesive-effusive-constrictive pericarditis, a very thickened pericardium and bilateral pleural effusion. After a pericardiectomy done to restore cardiac compensation and to identify etiological factors, a tuberculous pericarditis (TBP) was diagnosed. After surgery and starting anti-TB treatment, the patient presented altered clinical status, dyspnea, dry cough, fever and delayed callus formation at sternum level. Thoracic scan revealed mediastinal air collections, pericarditis and pleurisy. Thus, the TBP diagnosis was extended to mediastinal TB and anti-TB therapy was continued. After four months of treatment, another thoracic scan showed disappearance of the mediastinal air-leakage bubbles, multiple new micronodules in both lungs and lymph nodes of up to 15 mm; also increasing pericardial and pleural effusions. This case was interpreted as a TB treatment failure situation. A retreatment regimen was started, resulting in a slow favorable outcome. Pericardial TB is a rare condition, usually with delayed diagnosis and poor treatment benefits. Whenever possible, earlier diagnostic can contribute to better management of these cases. PMID:27151714

  8. Twisting of Red Blood Cells Entering a Constriction

    NASA Astrophysics Data System (ADS)

    Zeng, Nancy; Ristenpart, William

    2014-11-01

    Most work on the dynamic response of red blood cells (RBCs) to hydrodynamic stress has focused on linear velocity profiles. Relatively little experimental work has examined how individual RBCs respond to pressure driven flow in more complex geometries, such as the flow at the entrance of a capillary. Here, we establish the mechanical behaviors of healthy RBCs undergoing a sudden increase in shear stress at the entrance of a narrow constriction. We pumped RBCs through a constriction in an ex vivo microfluidic device and used high speed video to visualize and track the flow behavior of more than 4,400 RBCs. We show that approximately 85% of RBCs undergo one of four distinct modes of motion: stretching, twisting, tumbling, or rolling. Intriguingly, a plurality of cells (~30%) exhibited twisting (rotation around the major axis parallel to the flow direction), a mechanical behavior that is not typically observed in linear velocity profiles. We examine the mechanical origin of twisting using, as a limiting case, the equations of motion for rigid ellipsoids, and we demonstrate that the observed rotation is qualitatively consistent with rigid body theory.

  9. Mechanical Response of Red Blood Cells Entering a Constriction

    NASA Astrophysics Data System (ADS)

    Zeng, Nancy; Ristenpart, William

    2013-11-01

    Most work on RBC dynamic response to hydrodynamic stress has focused on linear velocity gradients. Relatively little experimental work has examined how RBCs respond to pressure driven flow in more complex geometries, such as in an abrupt contraction. Here, we establish the mechanical behaviors of RBCs undergoing a sudden increase in shear stress at the entrance of a narrow constriction. We pumped RBCs through a constriction in an ex vivo microfluidic device and used high speed video to visualize and track the flow behavior of more than 4,000 RBCs. We show that approximately 90% of RBCs undergo one of four distinct modes of motion: stretching, twisting, tumbling, or rolling. Intriguingly, almost 40% of the cells exhibited twisting (rotation around the major axis parallel to the flow direction), a mechanical behavior that is not typically observed in linear velocity gradients. We present detailed statistical analyses on the dynamics of each motion and demonstrate that the behavior is highly sensitive to the location of the RBC within the channel. Finally, we show that the tumbling and rolling motions can be rationalized qualitatively in terms of rigid body rotation, whereas twisting motion cannot, suggesting that twisting is a consequence of the viscoelastic nature of the RBCs.

  10. Aortic wraps a modification to aortic grafting.

    PubMed

    Gordon, J A

    1989-09-01

    Aortic wrapping has been attempted on occasion when the standard replacement of a diseased lower third of the aorta by a trouser graft is not feasible. Cellophane has been the most common agent employed, but these wraps have met with minimal success and on occasion has even been passed rectally. Kartchner and Lovett have reviewed the techniques and results of the later procedures replacing the cellophane wraps. In most instances a Dacron sheet was utilized. Six cases are reviewed from a solo private practice in which a standard trouser graft replacement was varied by using an alternative form of wrapping.

  11. Dynamics of single inclusions in channels with constrictions in the acoustic field

    NASA Astrophysics Data System (ADS)

    Maksimov, A. Yu.; Gubaidullin, A. A.

    2016-10-01

    The process of mobilization of viscous droplets, trapped in the channel with a sinusoidal constriction under the influence of an external acoustic field have been studied. The dependence of the amplitude of acoustic impact from the frequency has been found. The problem of the free longitudinal oscillations of a droplet in the absence of viscous friction forces in the channels with the constrictions was considered. The influence of surface tension, droplet volume and shape of constrictions on the natural frequency of the longitudinal oscillations of a droplet pinned at the constriction of the capillary were studied.

  12. A case of balanced type double aortic arch diagnosed incidentally by transthoracic echocardiography in an asymptomatic adult patient.

    PubMed

    Seo, Han Seok; Park, Yong Hyun; Lee, Ju Hyoung; Hur, So Chong; Ko, Yu Jin; Park, So Yeon; Kim, Jun Hwan; Kim, Young Jung; Kim, So Yon; Kwon, Nak Hyun

    2011-09-01

    A 36-year-old male patient with no remarkable medical history was admitted to our hospital for a health check up. On chest radiography, bilateral aortic notches at the level of aortic arch were shown suggesting aortic arch anomaly without any clinical symptoms. Two aortic arches were almost same-in-size on suprasternal view of transthoracic echocardiography. In addition, multidetector computed tomography showed balanced type double aortic arch forming a complete vascular ring which encircled the trachea and esophagus. The trachea was slightly compressed by the vascular ring whereas the esophagus was intact. Nevertheless, the pulmonary function test was normal. The patient was discharged from hospital with instructions for periodic follow-up.

  13. Experimental measurement of dynamic fluid shear stress on the aortic surface of the aortic valve leaflet

    PubMed Central

    Yap, Choon Hwai; Saikrishnan, Neelakantan; Tamilselvan, Gowthami

    2011-01-01

    Aortic valve (AV) calcification is a highly prevalent disease with serious impact on mortality and morbidity. Although exact causes and mechanisms of AV calcification are unclear, previous studies suggest that mechanical forces play a role. Since calcium deposits occur almost exclusively on the aortic surfaces of AV leaflets, it has been hypothesized that adverse patterns of fluid shear stress on the aortic surface of AV leaflets promote calcification. The current study characterizes AV leaflet aortic surface fluid shear stresses using Laser Doppler velocimetry and an in vitro pulsatile flow loop. The valve model used was a native porcine valve mounted on a suturing ring and preserved using 0.15% glutaraldehyde solution. This valve model was inserted in a mounting chamber with sinus geometries, which is made of clear acrylic to provide optical access for measurements. To understand the effects of hemodynamics on fluid shear stress, shear stress was measured across a range of conditions: varying stroke volumes at the same heart rate and varying heart rates at the same stroke volume. Systolic shear stress magnitude was found to be much higher than diastolic shear stress magnitude due to the stronger flow in the sinuses during systole, reaching up to 20 dyn/cm2 at mid-systole. Upon increasing stroke volume, fluid shear stresses increased due to stronger sinus fluid motion. Upon increasing heart rate, fluid shear stresses decreased due to reduced systolic duration that restricted the formation of strong sinus flow. Significant changes in the shear stress waveform were observed at 90 beats/ min, most likely due to altered leaflet dynamics at this higher heart rate. Overall, this study represents the most well-resolved shear stress measurements to date across a range of conditions on the aortic side of the AV. The data presented can be used for further investigation to understand AV biological response to shear stresses. PMID:21416247

  14. Preeclampsia Is Associated with Increased Central Aortic Pressure, Elastic Arteries Stiffness and Wave Reflections, and Resting and Recruitable Endothelial Dysfunction

    PubMed Central

    Torrado, Juan; Farro, Ignacio; Zócalo, Yanina; Farro, Federico; Sosa, Claudio; Scasso, Santiago; Alonso, Justo; Bia, Daniel

    2015-01-01

    Introduction. An altered endothelial function (EF) could be associated with preeclampsia (PE). However, more specific and complementary analyses are required to confirm this topic. Flow-mediated dilation (FMD), low-flow-mediated constriction (L-FMC), and hyperemic-related changes in carotid-radial pulse wave velocity (PWVcr) offer complementary information about “recruitability” of EF. Objectives. To evaluate, in healthy and hypertensive pregnant women (with and without PE), central arterial parameters in conjunction with “basal and recruitable” EF. Methods. Nonhypertensive (HP) and hypertensive pregnant women (gestational hypertension, GH; preeclampsia, PE) were included. Aortic blood pressure (BP), wave reflection parameters (AIx@75), aortic pulse wave velocity (PWVcf) and PWVcr, and brachial and common carotid stiffness and intima-media thickness were measured. Brachial FMD and L-FMC and hyperemic-related change in PWVcr were measured. Results. Aortic BP and AIx@75 were elevated in PE. PE showed stiffer elastic but not muscular arteries. After cuff deflation, PWVcr decreased in HP, while GH showed a blunted PWVcr response and PE showed a tendency to increase. Maximal FMD and L-FMC were observed in HP followed by GH; PE did not reach significant arterial constriction. Conclusion. Aortic BP and wave reflections as well as elastic arteries stiffness are increased in PE. PE showed both “resting and recruitable” endothelial dysfunctions. PMID:26351578

  15. Preeclampsia Is Associated with Increased Central Aortic Pressure, Elastic Arteries Stiffness and Wave Reflections, and Resting and Recruitable Endothelial Dysfunction.

    PubMed

    Torrado, Juan; Farro, Ignacio; Zócalo, Yanina; Farro, Federico; Sosa, Claudio; Scasso, Santiago; Alonso, Justo; Bia, Daniel

    2015-01-01

    Introduction. An altered endothelial function (EF) could be associated with preeclampsia (PE). However, more specific and complementary analyses are required to confirm this topic. Flow-mediated dilation (FMD), low-flow-mediated constriction (L-FMC), and hyperemic-related changes in carotid-radial pulse wave velocity (PWVcr) offer complementary information about "recruitability" of EF. Objectives. To evaluate, in healthy and hypertensive pregnant women (with and without PE), central arterial parameters in conjunction with "basal and recruitable" EF. Methods. Nonhypertensive (HP) and hypertensive pregnant women (gestational hypertension, GH; preeclampsia, PE) were included. Aortic blood pressure (BP), wave reflection parameters (AIx@75), aortic pulse wave velocity (PWVcf) and PWVcr, and brachial and common carotid stiffness and intima-media thickness were measured. Brachial FMD and L-FMC and hyperemic-related change in PWVcr were measured. Results. Aortic BP and AIx@75 were elevated in PE. PE showed stiffer elastic but not muscular arteries. After cuff deflation, PWVcr decreased in HP, while GH showed a blunted PWVcr response and PE showed a tendency to increase. Maximal FMD and L-FMC were observed in HP followed by GH; PE did not reach significant arterial constriction. Conclusion. Aortic BP and wave reflections as well as elastic arteries stiffness are increased in PE. PE showed both "resting and recruitable" endothelial dysfunctions.

  16. Congenital Anomalies of the Aortic Arch: Evaluation with the Use of Multidetector Computed Tomography

    PubMed Central

    Büyükbayraktar, Fatma Gül; Ölçer, Tülay; Cumhur, Turhan

    2009-01-01

    Congenital anomalies of the aortic arch have clinical importance, as the anomalies may be associated with vascular rings or other congenital cardiovascular diseases. Multidetector computed tomography (MDCT) angiography enables one to display the detailed anatomy of vascular structures and the spatial relationships with adjacent organs; this ability is the greatest advantage of the use of MDCT angiography in comparison to other imaging modalities in the evaluation of the congenital anomalies of the aortic arch. In this review article, we illustrate 16-slice MDCT angiography appearances of congenital anomalies of the aortic arch. PMID:19270864

  17. Exercise training reverses aging-induced impairment of myogenic constriction in skeletal muscle arterioles.

    PubMed

    Ghosh, Payal; Mora Solis, Fredy R; Dominguez, James M; Spier, Scott A; Donato, Anthony J; Delp, Michael D; Muller-Delp, Judy M

    2015-04-01

    To investigate whether exercise training can reverse age-related impairment of myogenic vasoconstriction in skeletal muscle arterioles, young (4 mo) and old (22 mo) male Fischer 344 rats were randomly assigned to either sedentary or exercise-trained groups. The roles of the endothelium and Kv1 channels in age- and exercise training-induced adaptations of myogenic responses were assessed through evaluation of pressure-induced constriction in endothelium-intact and denuded soleus muscle arterioles in the presence and absence of the Kv1 channel blocker, correolide. Exercise training enhanced myogenic constriction in arterioles from both old and young rats. In arterioles from old rats, exercise training restored myogenic constriction to a level similar to that of arterioles from young sedentary rats. Removal of the endothelium did not alter myogenic constriction of arterioles from young sedentary rats, but reduced myogenic constriction in arterioles from young exercise-trained rats. In contrast, endothelial removal had no effect on myogenic constriction of arterioles from old exercise-trained rats, but increased myogenic vasoconstriction in old sedentary rats. The effect of Kv1 channel blockade was also dependent on age and training status. In arterioles from young sedentary rats, Kv1 blockade had little effect on myogenic constriction, whereas in old sedentary rats Kv1 blockade increased myogenic constriction. After exercise training, Kv1 channel blockade increased myogenic constriction in arterioles from both young and old rats. Thus exercise training restores myogenic constriction of arterioles from old rats and enhances myogenic constriction from young rats through adaptations of the endothelium and smooth muscle Kv1 channels. PMID:25634999

  18. Regulation of contractile ring formation and septation in Schizosaccharomyces pombe.

    PubMed

    Willet, Alaina H; McDonald, Nathan A; Gould, Kathleen L

    2015-12-01

    The fission yeast Schizosaccharomyces pombe has become a powerful model organism for cytokinesis studies, propelled by pioneering genetic screens in the 1980s and 1990s. S. pombe cells are rod-shaped and divide similarly to mammalian cells, utilizing a medially-placed actin-and myosin-based contractile ring. A cell wall division septum is deposited behind the constricting ring, forming the new ends of each daughter cell. Here we discuss recent advances in our understanding of the regulation of contractile ring formation through formin proteins and the role of the division septum in S. pombe cell division.

  19. Ascending-to-descending aortic bypass and aortic valve replacement for concomitant severe aortic coarctation and aortic stenosis.

    PubMed

    Chu, Michael W A; Adams, Corey; Torres, Pedro

    2011-04-01

    We present a 33-year-old male with severe, symptomatic aortic coarctation and aortic stenosis assessed on a humanitarian medical mission to a developing country. Contemplating limited time and available resources, we performed a simultaneous single-stage approach with ascending-to-descending aortic bypass with a reinforced gortex graft and concomitant aortic valve replacement through a median sternotomy. The patient had an uneventful postoperative convalescence and was discharged on postoperative day 5. At 1-year follow-up, he was asymptomatic and doing well with good blood pressure control and complete equalization of upper and lower limb blood pressure measurements. Computed tomography and transthoracic echocardiography demonstrated a widely patent ascending-to-descending aortic bypass graft and a normally functioning prosthetic aortic valve, respectively. In developing countries where health care resources are limited, a combined approach with an extra-anatomic, thoracic aortic bypass, and aortic valve replacement resulted in good early and 1-year outcomes. This procedure may represent the most effective surgical option for patients with concomitant aortic coarctation and aortic stenosis.

  20. Genetics, Pregnancy, and Aortic Degeneration.

    PubMed

    Crawford, Jeffrey D; Hsieh, Cindy M; Schenning, Ryan C; Slater, Matthew S; Landry, Gregory J; Moneta, Gregory L; Mitchell, Erica L

    2016-01-01

    We present a case of familial thoracic aortic aneurysm and dissection (FTAAD) in a pregnant female. FTAAD is an inherited, nonsyndromic aortopathy resulting from several genetic mutations critical to aortic wall integrity have been identified. One such mutation is the myosin heavy chain gene (MYH11) which is responsible for 1-2% of all FTAAD cases. This mutation results in aortic medial degeneration, loss of elastin, and reticulin fiber fragmentation predisposing to TAAD. Aortic disease is more aggressive during pregnancy as a result of increased wall stress from hyperdynamic cardiovascular changes and estrogen-induced aortic media degeneration. Our patient was a 29-year-old G2P1 woman at 26 weeks gestation presenting with abdominal and back pain. Work-up revealed a 6.4-cm ascending aortic aneurysm with a type A dissection extending into all arch vessels, aortic coarctation at the isthmus, and a separate focal type B aortic dissection with visceral involvement. Surgical management included concomitant cesarean section with delivery of a live premature infant, tubal ligation, ascending aortic replacement with reconstruction of the arch vessels, and aortic valve resuspension. The type B dissection was managed medically without complication. This is the first reported case of aortic dissection in a patient with FTAAD/MYH11 mutation and pregnancy. This case highlights that FTAAD and pregnancy cause aortic degeneration via distinct mechanisms and that hyperdynamics of pregnancy increase aortic wall stress. Management of pregnancy associated with aortopathy requires early transfer to a tertiary center, careful investigation to identify familial aortopathy, fetal monitoring, and a multidisciplinary team approach. PMID:26381327

  1. Surgical Management of the Constricted or Obliterated Vagina.

    PubMed

    Gebhart, John B; Schmitt, Jennifer J

    2016-08-01

    Management of the constricted or obliterated vagina demands an understanding and recognition of the potential etiologies leading to this presentation. A thorough and comprehensive medical and surgical review is required to arrive at an accurate diagnosis, which then will guide medical or surgical intervention. It is paramount to recognize when underlying medical conditions are contributing to these conditions and to begin medical therapy; failure to do so will often yield suboptimal results. When these conditions arise after surgical interventions, compensatory surgical techniques that correct upper and lower vaginal strictures or obliteration include incision through the stricture, vaginal advancement, Z-plasty, skin grafts, perineal flaps, and abdominal flaps and grafts. Postoperative surveillance and dilation are critical to optimize long-term success. PMID:27399991

  2. [Diagnostic difficulties in a case of constricted tubular visual field].

    PubMed

    Dogaru, Oana-Mihaela; Rusu, Monica; Hâncu, Dacia; Horvath, Kárin

    2013-01-01

    In the paper below we present the clinical case of a 48 year old female with various symptoms associated with functional visual disturbance -constricted tubular visual fields, wich lasts from 6 years; the extensive clinical and paraclinical ophthalmological investigations ruled out the presence of an organic disorder. In the present, we suspect a diagnosis of hysteria, still uncertain, wich represented over time a big challenge in psychology and ophthalmology. The mechanisms and reasons for hysteria are still not clear and it could represent a fascinating research theme. The tunnel, spiral or star-shaped visual fields are specific findings in hysteria for patients who present visual disturbance. The question of whether or not a patient with hysterical visual impairment can or cannot "see" is still unresolved.

  3. Equivalence ratio and constriction effects on RBCC thrust augmentation

    NASA Astrophysics Data System (ADS)

    Koupriyanov, M.; Etele, J.

    2011-06-01

    A theoretical analysis of a variable area rocket based combined cycle engine with and without simultaneous mixing and combustion is presented. The flowfield is solved using a steady, quasi-one-dimensional, inviscid control volume formulation with combustion effects included via a generalized equilibrium calculation. Compression augmentation is shown to be sensitive to the equivalence ratio within the primary rocket chamber, where ejector section performance is greatest at both low and high equivalence ratios but near a minimum at stoichiometric conditions. The thrust generated by the RBCC engine compared to that generated by the same rocket in isolation can be increased by as much as 12% at constriction ratios of between 45% and 50%. Thrust augmentation is also shown to vary with equivalence ratio, where for a fixed geometry the maximum thrust is generated at equivalence ratios slightly below unity.

  4. First direct aortic retrievable transcatheter aortic valve implantation in humans.

    PubMed

    Chandrasekhar, Jaya; Glover, Chris; Labinaz, Marino; Ruel, Marc

    2014-11-01

    We describe 2 cases in which transcatheter aortic valve implantation was performed with a Portico prosthesis (St Jude Medical, St Paul, MN) through a direct aortic approach. In 1 of the cases, prosthesis retrieval was needed during the procedure and was essential to the successful outcome. This is the first report, to our knowledge, of direct aortic Portico prosthesis implantation, and it highlights the significance of the retrievable nature of this device. PMID:25442452

  5. Current constriction of high-current vacuum arc in vacuum interrupters

    SciTech Connect

    Wang Lijun; Jia Shenli; Zhang Ling; Yang Dingge; Shi Zongqian; Gentils, Francois; Jusselin, Benoit

    2008-03-15

    Compared with previous paper [L. Wang et al., J. Appl. Phys. 100, 113304 (2006)], higher-current vacuum arc is simulated and analyzed based on magnetohydrodynamics model, and current constriction phenomenon in arc column is mainly paid attention to and analyzed in this paper. According to simulation results, it can be found that significant current constriction only appears near anode regions for lower-current vacuum arc. However, with the increase of arc current, current constriction also appears near the cathode side, and with the further increase of arc current, current constriction near the cathode side can become more significant than that near the anode side. The current constriction near the cathode side can be mainly caused by very high current level. The increase of axial magnetic field (AMF) strength will inhibit current constriction in the whole arc column. For influence of AMF distribution, saddle-shaped distributed AMF can more efficiently inhibit current constriction of arc column than bell-shaped AMF. The phenomenon of current constriction near the cathode side has also been found by many experiments, which also can verify the correctness of simulation results.

  6. Embryo as an active granular fluid: stress-coordinated cellular constriction chains

    NASA Astrophysics Data System (ADS)

    Gao, Guo-Jie Jason; Holcomb, Michael C.; Thomas, Jeffrey H.; Blawzdziewicz, Jerzy

    2016-10-01

    Mechanical stress plays an intricate role in gene expression in individual cells and sculpting of developing tissues. However, systematic methods of studying how mechanical stress and feedback help to harmonize cellular activities within a tissue have yet to be developed. Motivated by our observation of the cellular constriction chains (CCCs) during the initial phase of ventral furrow formation in the Drosophila melanogaster embryo, we propose an active granular fluid (AGF) model that provides valuable insights into cellular coordination in the apical constriction process. In our model, cells are treated as circular particles connected by a predefined force network, and they undergo a random constriction process in which the particle constriction probability P is a function of the stress exerted on the particle by its neighbors. We find that when P favors tensile stress, constricted particles tend to form chain-like structures. In contrast, constricted particles tend to form compact clusters when P favors compression. A remarkable similarity of constricted-particle chains and CCCs observed in vivo provides indirect evidence that tensile-stress feedback coordinates the apical constriction activity. Our particle-based AGF model will be useful in analyzing mechanical feedback effects in a wide variety of morphogenesis and organogenesis phenomena.

  7. Flow of a Casson fluid through a locally-constricted porous channel: a numerical study

    NASA Astrophysics Data System (ADS)

    Amlimohamadi, Haleh; Akram, Maryammosadat; Sadeghy, Kayvan

    2016-05-01

    Flow of a Casson fluid through a two-dimensional porous channel containing a local constriction is numerically investigated assuming that the resistance offered by the porous medium obeys the Darcy's law. Treating the constriction as another porous medium which obeys the Darcy-Forcheimer model, the equations governing fluid flow in the main channel and the constriction itself are numerically solved using the finite-volume method (FVM) based on the pseudo-transient SIMPLE algorithm. It is shown that an increase in the porosity of the channel decreases the shear stress exerted on the constriction. On the other hand, an increase in the fluid's yield stress is predicted to increase the maximum shear stress experienced by the constriction near its crest. The porosity of the constriction itself is predicted to have a negligible effect on the plaque's shear stress. But, the momentum of the weak flow passing through the constriction is argued to lower the bulk fluid from separating downstream of the constriction.

  8. Embryo as an active granular fluid: stress-coordinated cellular constriction chains.

    PubMed

    Jason Gao, Guo-Jie; Holcomb, Michael C; Thomas, Jeffrey H; Blawzdziewicz, Jerzy

    2016-10-19

    Mechanical stress plays an intricate role in gene expression in individual cells and sculpting of developing tissues. However, systematic methods of studying how mechanical stress and feedback help to harmonize cellular activities within a tissue have yet to be developed. Motivated by our observation of the cellular constriction chains (CCCs) during the initial phase of ventral furrow formation in the Drosophila melanogaster embryo, we propose an active granular fluid (AGF) model that provides valuable insights into cellular coordination in the apical constriction process. In our model, cells are treated as circular particles connected by a predefined force network, and they undergo a random constriction process in which the particle constriction probability P is a function of the stress exerted on the particle by its neighbors. We find that when P favors tensile stress, constricted particles tend to form chain-like structures. In contrast, constricted particles tend to form compact clusters when P favors compression. A remarkable similarity of constricted-particle chains and CCCs observed in vivo provides indirect evidence that tensile-stress feedback coordinates the apical constriction activity. Our particle-based AGF model will be useful in analyzing mechanical feedback effects in a wide variety of morphogenesis and organogenesis phenomena. PMID:27545101

  9. Structural Failure of a Starr-Edwards Aortic Track Valve

    PubMed Central

    Ringel, Richard E.; Moulton, Anthony L.; Burns, Janet E.; Brenner, Joel I.; Berman, Michael A.

    1983-01-01

    Structural failure of a Model 2400 Starr-Edwards aortic track valve occurred suddenly, 4 years after implantation. At operation, the valve cage was removed from the descending aorta. Examination of the excised prosthesis disclosed minimal cloth wear and no evidence of infective growth; however, three struts were fractured above their insertion into the valve ring. To our knowledge, this type of valve malfunction has not been previously noted. Images PMID:15227160

  10. Fully nonlinear Goertler vortices in constricted channel flows and their effect on the onset of separation

    NASA Technical Reports Server (NTRS)

    Denier, James P.; Hall, Philip

    1992-01-01

    The development of fully nonlinear Goertler vortices in high Reynolds number flow in a symmetrically constricted channel is investigated. Attention is restricted to the case of 'strongly' constricted channels considered by Smith and Daniels (1981) for which the scaled constriction height is asymptotically large. Such flows are known to develop a Goldstein singularity and subsequently become separated at some downstream station past the point of maximum channel constriction. It is shown that these flows can support fully nonlinear Goertler vortices, of the form elucidated by Hall and Lakin (1988), for constrictions which have an appreciable region of local concave curvature upstream of the position at which separation occurs. The effect on the onset of separation due to the nonlinear Goertler modes is discussed. A brief discussion of other possible nonlinear states which may also have a dramatic effect in delaying (or promoting) separation is given.

  11. Effect of Strain Rate on the Mechanical Behavior of Red Blood Cells Entering a Constriction

    NASA Astrophysics Data System (ADS)

    Mancuso, Jordan; Ristenpart, William

    2014-11-01

    Most work on the effect of hydrodynamic stress on red blood cells (RBCs) has focused on linear velocity profiles. Microfluidic devices have provided a means to examine the mechanical behavior of RBCs undergoing a sudden increase in shear stress at the entrance of a constriction, with previous work primarily focused on a fixed constriction taper angle and corresponding hydrodynamic strain rate. Here we investigate the effect of strain rate on the stretching dynamics exhibited by RBCs as they enter a microfluidic constriction. Systematic variations in the constriction taper angle allow the strain rate to be precisely tuned, and high speed video yields precise measurements of the corresponding RBC deformations. We demonstrate that maximal RBC stretching occurs at an intermediate constriction taper angle, despite the lower magnitude of the strain rate. We interpret the results in terms of the time integral of the elongational strain rate, and we discuss the implications for shear-induced mechanotransduction.

  12. Fully nonlinear Goertler vortices in constricted channel flows and their effect on the onset of separation

    NASA Astrophysics Data System (ADS)

    Denier, James P.; Hall, Philip

    1992-07-01

    The development of fully nonlinear Goertler vortices in high Reynolds number flow in a symmetrically constricted channel is investigated. Attention is restricted to the case of 'strongly' constricted channels considered by Smith and Daniels (1981) for which the scaled constriction height is asymptotically large. Such flows are known to develop a Goldstein singularity and subsequently become separated at some downstream station past the point of maximum channel constriction. It is shown that these flows can support fully nonlinear Goertler vortices, of the form elucidated by Hall and Lakin (1988), for constrictions which have an appreciable region of local concave curvature upstream of the position at which separation occurs. The effect on the onset of separation due to the nonlinear Goertler modes is discussed. A brief discussion of other possible nonlinear states which may also have a dramatic effect in delaying (or promoting) separation is given.

  13. [Stent Grafting for Aortic Dissection].

    PubMed

    Uchida, Naomichi

    2016-07-01

    The purpose of stent graft for aortic dissection is to terminate antegrade blood flow into the false lumen through primary entry. Early intervention for primary entry makes excellent aortic remodeling and emergent stent grafting for complicated acute type B aortic dissection is supported as a class I. On the other hand stent grafting for chronic aortic dissection is controversial. Early stent grafting is considered with in 6 months after on-set if the diameter of the descending aorta is more than 40 mm. Additional interventions for residual false lumen on the downstream aorta are still required. Stent graft for re-entry, candy-plug technique, and double stenting, other effective re-interventions were reported. Best treatment on the basis of each anatomical and physical characteristics should be selected in each institution. Frozen elephant trunk is alternative procedure for aortic dissection without the need to take account of proximal anatomical limitation and effective for acute type A aortic dissection. PMID:27440026

  14. Aortic dimensions in Turner syndrome.

    PubMed

    Quezada, Emilio; Lapidus, Jodi; Shaughnessy, Robin; Chen, Zunqiu; Silberbach, Michael

    2015-11-01

    In Turner syndrome, linear growth is less than the general population. Consequently, to assess stature in Turner syndrome, condition-specific comparators have been employed. Similar reference curves for cardiac structures in Turner syndrome are currently unavailable. Accurate assessment of the aorta is particularly critical in Turner syndrome because aortic dissection and rupture occur more frequently than in the general population. Furthermore, comparisons to references calculated from the taller general population with the shorter Turner syndrome population can lead to over-estimation of aortic size causing stigmatization, medicalization, and potentially over-treatment. We used echocardiography to measure aortic diameters at eight levels of the thoracic aorta in 481 healthy girls and women with Turner syndrome who ranged in age from two to seventy years. Univariate and multivariate linear regression analyses were performed to assess the influence of karyotype, age, body mass index, bicuspid aortic valve, blood pressure, history of renal disease, thyroid disease, or growth hormone therapy. Because only bicuspid aortic valve was found to independently affect aortic size, subjects with bicuspid aortic valve were excluded from the analysis. Regression equations for aortic diameters were calculated and Z-scores corresponding to 1, 2, and 3 standard deviations from the mean were plotted against body surface area. The information presented here will allow clinicians and other caregivers to calculate aortic Z-scores using a Turner-based reference population. © 2015 Wiley Periodicals, Inc.

  15. Aortic dimensions in Turner syndrome.

    PubMed

    Quezada, Emilio; Lapidus, Jodi; Shaughnessy, Robin; Chen, Zunqiu; Silberbach, Michael

    2015-11-01

    In Turner syndrome, linear growth is less than the general population. Consequently, to assess stature in Turner syndrome, condition-specific comparators have been employed. Similar reference curves for cardiac structures in Turner syndrome are currently unavailable. Accurate assessment of the aorta is particularly critical in Turner syndrome because aortic dissection and rupture occur more frequently than in the general population. Furthermore, comparisons to references calculated from the taller general population with the shorter Turner syndrome population can lead to over-estimation of aortic size causing stigmatization, medicalization, and potentially over-treatment. We used echocardiography to measure aortic diameters at eight levels of the thoracic aorta in 481 healthy girls and women with Turner syndrome who ranged in age from two to seventy years. Univariate and multivariate linear regression analyses were performed to assess the influence of karyotype, age, body mass index, bicuspid aortic valve, blood pressure, history of renal disease, thyroid disease, or growth hormone therapy. Because only bicuspid aortic valve was found to independently affect aortic size, subjects with bicuspid aortic valve were excluded from the analysis. Regression equations for aortic diameters were calculated and Z-scores corresponding to 1, 2, and 3 standard deviations from the mean were plotted against body surface area. The information presented here will allow clinicians and other caregivers to calculate aortic Z-scores using a Turner-based reference population. © 2015 Wiley Periodicals, Inc. PMID:26118429

  16. Almanac 2014: aortic valve disease.

    PubMed

    Otto, Catherine M

    2015-06-01

    The past few years have seen major advances in the diagnosis of aortic valve disease and in our understanding of the pathophysiology of disease. In addition, transcatheter aortic valve implantation has transformed our clinical management options. This article summarises new aortic valve disease research published in Heart in 2013 and 2014, within the context of other major studies published in general medical journals, including a discussion of the potential impact of these new research findings on the clinical approach to management of adults with aortic valve disease.

  17. Infrarenal Aortic Occlusion

    PubMed Central

    Traverso, L. W.; Baker, J. D.; Dainko, E. A.; Machleder, H. I.

    1978-01-01

    Twenty-eight patients with total occlusion of the infrarenal aorta have been seen at the UCLA Hospitals in the past 11 years. Claudication was the presenting complaint in all but one patient, with one-third having ischemic rest pain. The average age of these patients was 54 years, and their histories revealed a surprising absence of myocardial infarction, stroke, or diabetes, although 40% had essential hypertension. Heavy tobacco use, however, was characteristic of the entire group. Arteriography proved valuable in identifying and characterizing the vascular abnormalities, but posed problems in technique and interpretation. Significant distal arterial disease was detected radiographically in only 21% of these patients. Operative correction of the aortic occlusion was performed on 26 patients, 18 by aortic bypass grafts and eight by aorto-iliac endarterectomy, with one early postoperative death. Although the thrombus extended to the renal artery origins in 77% of the cases, a well-designed technical approach did not require renal artery occlusion. Using serial creatinine determinations, one case of renal insufficiency was detected which was associated with prolonged postoperative hypotension. Although the extent of distal disease was more severe in those who underwent bypass, symptoms of claudication returned earlier and were more prominent in the endarterectomy group. This recurrence of systems was not favorably altered by sympathectomy performed concomitantly with the initial procedure. Even though this condition seems to pose difficult technical obstacles and has a poor prognosis, infrarenal aortic occlusion can be successfully treated by aortic bypass, with favorable long-term results, if particular attention is paid to elements of the preoperative evaluation and the intraoperative technical requirements peculiar to this relatively uncommon disease entity. ImagesFig. 1.Fig. 2.Fig. 3. PMID:646479

  18. Neuroprotection during aortic surgery.

    PubMed

    Lindsay, Helen; Srinivas, Coimbatore; Djaiani, George

    2016-09-01

    Neurological injury is a major limitation of aortic surgery, whether it involves spinal cord injury following intervention to the thoracoabdominal aorta, or stroke following surgery on the arch and ascending aorta. Despite an extensive body of literature and various proposals, a completely effective strategy to prevent or treat neurological injury remains elusive. In this article, we summarise the evidence for established and emerging strategies, and review current concepts in pathophysiology and risk assessment as they relate to neurological injury. PMID:27650340

  19. Planetary Rings

    NASA Technical Reports Server (NTRS)

    Cuzzi, Jeffrey N.

    1994-01-01

    Just over two decades ago, Jim Pollack made a critical contribution to our understanding of planetary ring particle properties, and resolved a major apparent paradox between radar reflection and radio emission observations. At the time, particle properties were about all there were to study about planetary rings, and the fundamental questions were, why is Saturn the only planet with rings, how big are the particles, and what are they made of? Since then, we have received an avalanche of observations of planetary ring systems, both from spacecraft and from Earth. Meanwhile, we have seen steady progress in our understanding of the myriad ways in which gravity, fluid and statistical mechanics, and electromagnetism can combine to shape the distribution of the submicron-to-several-meter size particles which comprise ring systems into the complex webs of structure that we now know them to display. Insights gained from studies of these giant dynamical analogs have carried over into improved understanding of the formation of the planets themselves from particle disks, a subject very close to Jim's heart. The now-complete reconnaissance of the gas giant planets by spacecraft has revealed that ring systems are invariably found in association with families of regular satellites, and there is ark emerging perspective that they are not only physically but causally linked. There is also mounting evidence that many features or aspects of all planetary ring systems, if not the ring systems themselves, are considerably younger than the solar system

  20. Transcatheter aortic valve implantation.

    PubMed

    Nielsen, Hans Henrik Møller

    2012-12-01

    Transcatheter aortic valve implantation (TAVI) was introduced experimentally in 1989, based on a newly developed heart valve prosthesis - the stentvalve. The valve was invented by a Danish cardiologist named Henning Rud Andersen. The new valve was revolutionary. It was foldable and could be inserted via a catheter through an artery in the groin, without the need for heart lung machine. This allowed for a new valve implantation technique, much less invasive than conventional surgical aortic valve replacement (SAVR). Surgical aortic valve replacement is safe and improves symptoms along with survival. However, up to 1/3 of patients with aortic valve stenosis cannot complete the procedure due to frailty. The catheter technique was hoped to provide a new treatment option for these patients. The first human case was in 2002, but more widespread clinical use did not begin until 2006-2010. Today, in 2011, more than 40,000 valves have been implanted worldwide. Initially, because of the experimental character of the procedure, TAVI was reserved for patients who could not undergo SAVR due to high risk. The results in this group of patients were promising. The procedural safety was acceptable, and the patients experienced significant improvements in their symptoms. Three of the papers in this PhD-thesis are based on the outcome of TAVI at Skejby Hospital, in this high-risk population [I, II and IV]. Along with other international publications, they support TAVI as being superior to standard medical treatment, despite a high risk of prosthetic regurgitation. These results only apply to high-risk patients, who cannot undergo SAVR. The main purpose of this PhD study has been to investigate the quality of TAVI compared to SAVR, in order to define the indications for this new procedure. The article attached [V] describes a prospective clinical randomised controlled trial, between TAVI to SAVR in surgically amenable patients over 75 years of age with isolated aortic valve stenosis

  1. Lulu Regulates Shroom-Induced Apical Constriction during Neural Tube Closure

    PubMed Central

    Chu, Chih-Wen; Gerstenzang, Emma; Ossipova, Olga; Sokol, Sergei Y.

    2013-01-01

    Apical constriction is an essential cell behavior during neural tube closure, but its underlying mechanisms are not fully understood. Lulu, or EPB4.1l5, is a FERM domain protein that has been implicated in apical constriction and actomyosin contractility in mouse embryos and cultured cells. Interference with the function of Lulu in Xenopus embryos by a specific antisense morpholino oligonucleotide or a carboxy-terminal fragment of Lulu impaired apical constriction during neural plate hinge formation. This effect was likely due to lack of actomyosin contractility in superficial neuroectodermal cells. By contrast, overexpression of Lulu RNA in embryonic ectoderm cells triggered ectopic apico-basal elongation and apical constriction, accompanied by the apical recruitment of F-actin. Depletion of endogenous Lulu disrupted the localization and activity of Shroom3, a PDZ-containing actin-binding protein that has also been implicated in apical constriction. Furthermore, Lulu and Shroom3 RNAs cooperated in triggering ectopic apical constriction in embryonic ectoderm. Our findings reveal that Lulu is essential for Shroom3-dependent apical constriction during vertebrate neural tube closure. PMID:24282618

  2. Quadricuspid Aortic Valve: A Rare Congenital Cause of Aortic Insufficiency

    PubMed Central

    Vasudev, Rahul; Shah, Priyank; Bikkina, Mahesh; Shamoon, Fayez

    2016-01-01

    Quadricuspid aortic valve (QAV) is a rare congenital cardiac anomaly causing aortic regurgitation usually in the fifth to sixth decade of life. Earlier, the diagnosis was mostly during postmortem or intraoperative, but now with the advent of better imaging techniques such as transthoracic echocardiography, transesophageal echocardiography (TEE), and cardiac magnetic resonance imaging, more cases are being diagnosed in asymptomatic patients. We present a case of a 39-year-old male who was found to have QAV, with the help of TEE, while undergoing evaluation for a diastolic murmur. The patient was found to have Type B QAV with moderate aortic regurgitation. We also present a brief review of classification, pathophysiology, and embryological basis of this rare congenital anomaly. The importance of diagnosing QAV lies in the fact that majority of these patients will require surgery for aortic regurgitation and close follow-up so that aortic valve replacement/repair is done before the left ventricular decompensation occurs. PMID:27195176

  3. Management of Acute Aortic Syndrome and Chronic Aortic Dissection

    SciTech Connect

    Nordon, Ian M. Hinchliffe, Robert J.; Loftus, Ian M.; Morgan, Robert A.; Thompson, Matt M.

    2011-10-15

    Acute aortic syndrome (AAS) describes several life-threatening aortic pathologies. These include intramural hematoma, penetrating aortic ulcer, and acute aortic dissection (AAD). Advances in both imaging and endovascular treatment have led to an increase in diagnosis and improved management of these often catastrophic pathologies. Patients, who were previously consigned to medical management or high-risk open surgical repair, can now be offered minimally invasive solutions with reduced morbidity and mortality. Information from the International Registry of Acute Aortic Dissection (IRAD) database demonstrates how in selected patients with complicated AAD the 30-day mortality from open surgery is 17% and endovascular stenting is 6%. Despite these improvements in perioperative deaths, the risks of stroke and paraplegia remain with endovascular treatment (combined outcome risk 4%). The pathophysiology of each aspect of AAS is described. The best imaging techniques and the evolving role of endovascular techniques in the definitive management of AAS are discussed incorporating strategies to reduce perioperative morbidity.

  4. Theory of nonlinear ballistic transport in quasi-one-dimensional constrictions

    NASA Astrophysics Data System (ADS)

    Xu, Hongqi

    1993-06-01

    We report on quantum-mechanical calculations of the differential conductance G of a ballistic and uniform constriction in the nonlinear-response regime of transport. The constriction has been connected to two semi-infinite two-dimensional electron gases, which serve as emitter and collector when a source-drain voltage Vsd is applied. In accordance with the fact that there should not be any electron backscatterings in the idealized constriction, it is assumed, in the calculations, that the electrostatic potential is flat in the constriction along the transport direction and the voltage drops of the applied source-drain voltage occur only at the ends of the constriction. Our calculations show that in addition to the conductance plateaus, which are quantized at multiples of 2e2/h in the linear-response regime of transport, new plateau structure develops as the source-drain voltage is increased. We predict that the edges of the conductance plateaus are shifted linearly with the applied source-drain voltage. Based on this prediction we discuss a method proposed for measuring the energy spacings of the sublevels of the constriction. Under the assumption that the transmission of an electron depends only on the difference between the energy of the electron incident on the constriction and the bottom of the electrostatic confining potential, a simple analytical form is derived for the nonlinear differential conductance of the constriction. This form complements our exact calculational results and shows that at zero temperature the differential conductance at a given finite Vsd and a given Fermi energy EF is a weighted average of two zero-Vsd conductances at Fermi energies of EF+(1-α)eVsd and EF-αeVsd, where α describes the fraction of the source-drain voltage that drops on the connection between the constriction and the drain reservoir.

  5. Sodium Hydrosulfide Relieves Neuropathic Pain in Chronic Constriction Injured Rats

    PubMed Central

    Lin, Jian-qing; Luo, Hui-qin; Lin, Cai-zhu; Chen, Jin-zhuan; Lin, Xian-zhong

    2014-01-01

    Aberrant neuronal activity in injured peripheral nerves is believed to be an important factor in the development of neuropathic pain (NPP). Channel protein pCREB of that activity has been shown to mitigate the onset of associated molecular events in the nervous system, and sodium hydrosulfide (NaHS) could inhibit the expression of pCREB. However, whether NaHS could relieve the pain, it needs further experimental research. Furthermore, the clinical potential that NaHS was used to relieve pain was limited so it would be required. To address these issues, the rats of sciatic nerve chronic constriction injury (CCI) were given intraperitoneal injection of NaHS containing hydrogen sulfide (H2S). The experimental results showed that NaHS inhibited the reduction of paw withdrawal thermal latency (PWTL), mechanical withdrawal threshold (MWT), and the level of pCREB in CCI rats in a dose-dependent manner and they were greatly decreased in NaHSM group (P < 0.05). NaHS alleviates chronic neuropathic pain by inhibiting expression of pCREB in the spinal cord of Sprague-Dawley rats. PMID:25506383

  6. Snap-off in constricted capillary with elastic interface

    NASA Astrophysics Data System (ADS)

    Hoyer, P.; Alvarado, V.; Carvalho, M. S.

    2016-01-01

    Snap-off of bubbles and drops in constricted capillaries occurs in many different situations, from bio-fluid to multiphase flow in porous media. The breakup process has been extensively analyzed both by theory and experiments, but most work has been limited to pure interfaces, at which the surface stress is isotropic and fully defined by the interfacial tension and interface curvature. Complex interfaces may present viscous and elastic behavior leading to a complex stress state that may change the dynamics of the interface deformation and breakup. We extend the available asymptotic model based on lubrication approximation to include elastic interfacial stress. Drop breakup time is determined as a function of the capillary geometry and liquid properties, including the interfacial elastic modulus. Results show that the interfacial elasticity has a stabilizing effect by slowing down the growth of the liquid collar, leading to a larger break-up time. This stabilizing effect has been observed experimentally in different, but related flows [Alvarado et al., "Interfacial visco-elasticity of crude oil-brine: An alternative EOR mechanism in smart waterflooding," in SPE-169127 Improved Oil Recovery Symposium (Society of Petroleum Engineers, 2014)].

  7. Noninvasive detection of airway constriction in awake guinea pigs

    SciTech Connect

    Silbaugh, S.A.; Mauderly, J.L.

    1984-01-01

    Tidal volume measured by the barometric method is very sensitive to increases in compression and expansion of alveolar gas, such as would be expected to occur during airway narrowing or closure. By comparing a barometric method tidal volume signal (VT') with a reference tidal volume (VT) obtained with a head-out pressure plethysmograph, a simple index related to gas compressibility effects was calculated (VT/VT'). Changes in this index were compared with decreases in dynamic compliance (Cdyn) during histamine aerosol challenge of 15 Charles River Hartley guinea pigs. Decreases in VT/VT' occurred during all aerosol challenges and were correlated with decreases in Cdyn. Decreases in VT/VT' were most marked at Cdyn values of less than 50% of base line. At Cdyn of less than 15% of base line, VT' was 3.1-4.8 times the VT reference signal. No increase in total pulmonary resistance was noted, and Cdyn and VT/VT' returned to base line after histamine exposure was stopped. The authors conclude that gas compressibility effects become substantial during histamine-induced airway constriction in the guinea pig and that the VT/VT' ratio appears to provide a simple noninvasive method of detecting these changes.

  8. Sodium hydrosulfide relieves neuropathic pain in chronic constriction injured rats.

    PubMed

    Lin, Jian-Qing; Luo, Hui-Qin; Lin, Cai-Zhu; Chen, Jin-Zhuan; Lin, Xian-Zhong

    2014-01-01

    Aberrant neuronal activity in injured peripheral nerves is believed to be an important factor in the development of neuropathic pain (NPP). Channel protein pCREB of that activity has been shown to mitigate the onset of associated molecular events in the nervous system, and sodium hydrosulfide (NaHS) could inhibit the expression of pCREB. However, whether NaHS could relieve the pain, it needs further experimental research. Furthermore, the clinical potential that NaHS was used to relieve pain was limited so it would be required. To address these issues, the rats of sciatic nerve chronic constriction injury (CCI) were given intraperitoneal injection of NaHS containing hydrogen sulfide (H2S). The experimental results showed that NaHS inhibited the reduction of paw withdrawal thermal latency (PWTL), mechanical withdrawal threshold (MWT), and the level of pCREB in CCI rats in a dose-dependent manner and they were greatly decreased in NaHSM group (P < 0.05). NaHS alleviates chronic neuropathic pain by inhibiting expression of pCREB in the spinal cord of Sprague-Dawley rats.

  9. Balloon aortic valvuloplasty as a bridge to aortic valve surgery for severe aortic stenosis.

    PubMed

    Nwaejike, Nnamdi; Mills, Keith; Stables, Rod; Field, Mark

    2015-03-01

    A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was, in patients with severe aortic stenosis, can balloon valvuloplasty be used as a bridge to aortic valve replacement? Altogether 463 papers were found using the reported search, of which 11 papers represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. We conclude that balloon aortic valvuloplasty is recommended as a bridge to aortic valve replacement (AVR) or transcatheter aortic valve implantation (TAVI) in patients with severe symptomatic aortic stenosis. Institutional practices, local and logistic factors can affect patient selection and management approaches to severe aortic stenosis, but having the facility to offer balloon aortic valvuloplasty (especially in the TAVI era) provides another management option for patients who would otherwise have been considered unacceptably high risk for aortic valve surgery. The increased incidence of balloon aortic valvuloplasty mirrors the increase in the use of TAVI with a sharp increase in activity from 2006. Success rates for bridging from balloon aortic valvuloplasty to definite surgical intervention are in the range 26.3-74%, with AVR or TAVI occurring within 8 weeks to 7 months. Complications from balloon aortic valvuloplasty such as aortic regurgitation (AR) can be managed successfully. Up to 40% of patients selected by balloon aortic valvuloplasty to have TAVI or AVR do not have these procedures within 2 years. While most of these patients are excluded for objective clinical reasons such as terminal disease/malignancy or other persistent contraindication, some patients refuse definitive treatment and others die while on the waiting list. Outcomes in patients bridged to AVR/TAVI are better than in patients treated with balloon aortic valvuloplasty

  10. Thoracic aortic aneurysms and pregnancy.

    PubMed

    Coulon, Capucine

    2015-11-01

    Half of acute aortic dissection in women under the age of 40 occurs during pregnancy or peripartum period. Marfan syndrome is the most common syndromic presentation of ascending aortic aneurysm, but other syndromes such as vascular Ehlers-Danlos syndrome, Loeys-Dietz syndrome and Turner syndrome also have ascending aortic aneurysms and the associated cardiovascular risk of aortic dissection and rupture. Management of aortic root aneurysm has been established in recent recommendations, even if levels of evidence are weak. Pregnancy and postpartum period should be followed very closely and determined to be at high risk. Guidelines suggest that women with aortopathy should be counseled against the risk of pregnancy and about the heritable nature of the disease prior to pregnancy.

  11. New Insights Into Aortic Diseases

    PubMed Central

    Kuivaniemi, Helena; Sakalihasan, Natzi; Lederle, Frank A.; Jones, Gregory T.; Defraigne, Jean-Olivier; Labropoulos, Nicos; Legrand, Victor; Michel, Jean-Baptiste; Nienaber, Christoph; Radermecker, Marc A.; Elefteriades, John A.

    2013-01-01

    The current state of research and treatment on aortic diseases was discussed in the “3rd International Meeting on Aortic Diseases” (IMAD3) held on October 4–6, 2012, in Liège, Belgium. The 3-day meeting covered a wide range of topics related to thoracic aortic aneurysms and dissections, abdominal aortic aneurysms, and valvular diseases. It brought together clinicians and basic scientists and provided an excellent opportunity to discuss future collaborative research projects for genetic, genomics, and biomarker studies, as well as clinical trials. Although great progress has been made in the past few years, there are still a large number of unsolved questions about aortic diseases. Obtaining answers to the key questions will require innovative, interdisciplinary approaches that integrate information from epidemiological, genetic, molecular biology, and bioengineering studies on humans and animal models. It is more evident than ever that multicenter collaborations are needed to accomplish these goals. PMID:26798669

  12. Thoracic aortic aneurysms and pregnancy.

    PubMed

    Coulon, Capucine

    2015-11-01

    Half of acute aortic dissection in women under the age of 40 occurs during pregnancy or peripartum period. Marfan syndrome is the most common syndromic presentation of ascending aortic aneurysm, but other syndromes such as vascular Ehlers-Danlos syndrome, Loeys-Dietz syndrome and Turner syndrome also have ascending aortic aneurysms and the associated cardiovascular risk of aortic dissection and rupture. Management of aortic root aneurysm has been established in recent recommendations, even if levels of evidence are weak. Pregnancy and postpartum period should be followed very closely and determined to be at high risk. Guidelines suggest that women with aortopathy should be counseled against the risk of pregnancy and about the heritable nature of the disease prior to pregnancy. PMID:26454306

  13. Intraoperative aortic dissection

    PubMed Central

    Singh, Ajmer; Mehta, Yatin

    2015-01-01

    Intraoperative aortic dissection is a rare but fatal complication of open heart surgery. By recognizing the population at risk and by using a gentle operative technique in such patients, the surgeon can usually avoid iatrogenic injury to the aorta. Intraoperative transesophageal echocardiography and epiaortic scanning are invaluable for prompt diagnosis and determination of the extent of the injury. Prevention lies in the strict control of blood pressure during cannulation/decannulation, construction of proximal anastomosis, or in avoiding manipulation of the aorta in high-risk patients. Immediate repair using interposition graft or Dacron patch graft is warranted to reduce the high mortality associated with this complication. PMID:26440240

  14. Jupiter's ring

    NASA Technical Reports Server (NTRS)

    1979-01-01

    First evidence of a ring around the planet Jupiter is seen in this photograph taken by Voyager 1 on March 4, 1979. The multiple exposure of the extremely thin faint ring appears as a broad light band crossing the center of the picture. The edge of the ring is 1,212,000 km from the spacecraft and 57,000 km from the visible cloud deck of Jupiter. The background stars look like broken hair pins because of spacecraft motion during the 11 minute 12 second exposure. The wavy motion of the star trails is due to the ultra-slow natural oscillation of the spacecraft (with a period of 78 seconds). The black dots are geometric calibration points in the camera. The ring thickness is estimated to be 30 km or less. The photograph was part of a sequence planned to search for such rings in Jupiter's equatorial plane. The ring has been invisible from Earth because of its thinness and its transparency when viewed at any angle except straight on. JPL manages and controls the Voyager Project for NASA's Office of Space Science.

  15. The big squeeze: scaling of constriction pressure in two of the world's largest snakes, Python reticulatus and Python molurus bivittatus.

    PubMed

    Penning, David A; Dartez, Schuyler F; Moon, Brad R

    2015-11-01

    Snakes are important predators that have radiated throughout many ecosystems, and constriction was important in their radiation. Constrictors immobilize and kill prey by using body loops to exert pressure on their prey. Despite its importance, little is known about constriction performance or its full effects on prey. We studied the scaling of constriction performance in two species of giant pythons (Python reticulatus and Python molurus bivittatus) and propose a new mechanism of prey death by constriction. In both species, peak constriction pressure increased significantly with snake diameter. These and other constrictors can exert pressures dramatically higher than their prey's blood pressure, suggesting that constriction can stop circulatory function and perhaps kill prey rapidly by over-pressurizing the brain and disrupting neural function. We propose the latter 'red-out effect' as another possible mechanism of prey death from constriction. These effects may be important to recognize and treat properly in rare cases when constrictors injure humans.

  16. Thoracic endovascular aortic repair for blunt thoracic aortic injuries in complex aortic arch vessels anatomies.

    PubMed

    Piffaretti, Gabriele; Carrafiello, Gianpaolo; Ierardi, Anna Maria; Mariscalco, Giovanni; Macchi, Edoardo; Castelli, Patrizio; Tozzi, Matteo; Franchin, Marco

    2015-08-01

    The aim of this study is to report the use of thoracic endovascular aortic repair (TEVAR) in blunt thoracic aortic injuries (BTAIs) presenting with complex anatomies of the aortic arch vessels. Two patients were admitted to our hospital for the management of BTAI. Anomalies were as follow: aberrant right subclavian artery (n = 1) and right-sided aortic arch with 5 vessels anatomy variant (n = 1). TEVAR was accomplished using parallel graft with periscope configuration in the patient with the aberrant right subclavian artery. At 12-month follow-up, computed tomography angiographies confirmed the exclusion of the BTAI, the stability of the endograft, the resolution of the pseudoaneurysm, and the patency of the parallel endograft. Aortic arch vessels variants and anomalies are not rare, and should be recognized and studied precisely to plan the most appropriate operative treatment. TEVAR proved to be effective even in complex anatomies.

  17. Aortic biomechanics in hypertrophic cardiomyopathy

    PubMed Central

    Badran, Hala Mahfouz; Soltan, Ghada; Faheem, Nagla; Elnoamany, Mohamed Fahmy; Tawfik, Mohamed; Yacoub, Magdi

    2015-01-01

    Background: Ventricular-vascular coupling is an important phenomenon in many cardiovascular diseases. The association between aortic mechanical dysfunction and left ventricular (LV) dysfunction is well characterized in many disease entities, but no data are available on how these changes are related in hypertrophic cardiomyopathy (HCM). Aim of the work: This study examined whether HCM alone is associated with an impaired aortic mechanical function in patients without cardiovascular risk factors and the relation of these changes, if any, to LV deformation and cardiac phenotype. Methods: 141 patients with HCM were recruited and compared to 66 age- and sex-matched healthy subjects as control group. Pulse pressure, aortic strain, stiffness and distensibility were calculated from the aortic diameters measured by M-mode echocardiography and blood pressure obtained by sphygmomanometer. Aortic wall systolic and diastolic velocities were measured using pulsed wave Doppler tissue imaging (DTI). Cardiac assessment included geometric parameters and myocardial deformation (strain and strain rate) and mechanical dyssynchrony. Results: The pulsatile change in the aortic diameter, distensibility and aortic wall systolic velocity (AWS') were significantly decreased and aortic stiffness index was increased in HCM compared to control (P < .001) In HCM AWS' was inversely correlated to age(r = − .32, P < .0001), MWT (r = − .22, P < .008), LVMI (r = − .20, P < .02), E/Ea (r = − .16, P < .03) LVOT gradient (r = − 19, P < .02) and severity of mitral regurg (r = − .18, P < .03) but not to the concealed LV deformation abnormalities or mechanical dyssynchrony. On multivariate analysis, the key determinant of aortic stiffness was LV mass index and LVOT obstruction while the role LV dysfunction in aortic stiffness is not evident in this population. Conclusion: HCM is associated with abnormal aortic mechanical properties. The severity of cardiac

  18. Cytoplasmic constriction and vesiculation after axotomy in the squid giant axon.

    PubMed

    Gallant, P E; Hammar, K; Reese, T S

    1995-12-01

    The squid giant axon responded to a transection injury by producing a gradient of cytoplasmic and vesicular changes at the cut end. At the immediate opening of the cut axon the cytoplasm was fragmented and dispersed and the vesicles in this region were in rapid Brownian movement. Approximately 0.1 mm further in, at the site of maximal axonal constriction, the axoplasm was condensed into a compact, constricted mass containing many large vesicles. The axoplasm was normal a few millimetres beyond this constricted, vesiculated end. It appears that transection triggered the transformation of normal axoplasm into a tightly constricted, highly vesiculated structure. This modified axoplasm at the cut end may slow the spread of damage and degeneration by preventing the bulk outflow of axoplasm, by slowing down the loss of intracellular molecules and by slowing down the influx of destructive extracellular ions (like calcium and chloride).

  19. Apical constriction: themes and variations on a cellular mechanism driving morphogenesis

    PubMed Central

    Martin, Adam C.; Goldstein, Bob

    2014-01-01

    Apical constriction is a cell shape change that promotes tissue remodeling in a variety of homeostatic and developmental contexts, including gastrulation in many organisms and neural tube formation in vertebrates. In recent years, progress has been made towards understanding how the distinct cell biological processes that together drive apical constriction are coordinated. These processes include the contraction of actin-myosin networks, which generates force, and the attachment of actin networks to cell-cell junctions, which allows forces to be transmitted between cells. Different cell types regulate contractility and adhesion in unique ways, resulting in apical constriction with varying dynamics and subcellular organizations, as well as a variety of resulting tissue shape changes. Understanding both the common themes and the variations in apical constriction mechanisms promises to provide insight into the mechanics that underlie tissue morphogenesis. PMID:24803648

  20. Vessel constriction correlated with local singlet oxygen generation during vascular targeted photodynamic therapy

    NASA Astrophysics Data System (ADS)

    Lin, Lisheng; Li, Yirong; Zhang, Jinde; Tan, Zou; Chen, Defu; Xie, Shusen; Gu, Ying; Li, Buhong

    2014-11-01

    In this study, the vessel constriction was measured as a biological indicator of acute vascular response after vascular targeted photodynamic therapy (V-PDT). During V-PDT treatment, the near-infrared (NIR) singlet oxygen (1O2) luminescence at 1270 nm generated in blood vessels in a dorsal skinfold window chamber model in vivo was directly monitored using a custom built high-sensitive NIR imaging system. In order to compare the acute vascular response, various irradiances with the same light dose were utilized for treatments. The obtained results show that the complete arteriole constriction occurred frequently, while some of the larger veins were constricted partially. For the vessels that have significant constriction after V-PDT, our preliminary data suggest that the vasoconstriction in the selected ROIs are roughly correlated with the local cumulative 1O2 luminescence intensities. This study implies that the 1O2 luminescence dosimetry maybe also effective for evaluating V-PDT efficiency.

  1. Constricted tube system for presumptive identification and differentiation of group D streptococci.

    PubMed

    Takeguchi, M M; Simpson, L B

    1979-04-01

    A single, constricted tube containing two differential media to identify and differentiate group D streptococci was developed. Test results with a limited number of group D streptococcal isolates were in complete agreement with results of conventional procedures.

  2. Abdominal aortic grafting for spontaneous infrarenal abdominal aortic dissection.

    PubMed

    Iwasaki, Hiroto; Shibuya, Takashi; Shintani, Takashi; Uenaka, Hisazumi; Suehiro, Shigefumi; Satoh, Hisashi

    2010-02-01

    This case report concerns a 62-year-old woman with spontaneous infrarenal abdominal aortic dissection, which developed into claudication and rest pain in the lower extremity. Multi-row detector computed tomography showed the entry site of the abdominal aortic dissection at the second lumbar artery, while the reentry site was found intraoperatively at the median sacral artery, indicating that the false lumen had progressed and compressed the true lumen. A direct approach involving grafting appears to be an effective procedure for resolving mesenteric and lower extremity hypoperfusion due to aortic dissection with a dilated false channel, even during the acute period. PMID:19879731

  3. Transcatheter aortic valve implantation in bicuspid aortic valve stenosis.

    PubMed

    Perlman, Gidon Y; Blanke, Philipp; Webb, John G

    2016-09-18

    Bicuspid aortic stenosis (AS) is not rare in patients treated with transcatheter aortic valve implantation (TAVI). Bicuspid valves have unique anatomy which could affect the results of TAVI; however, multiple recent reports have shown that TAVI is safe and effective in this population. Paravalvular aortic regurgitation was initially found to be more frequent in bicuspid patients, but newer-generation devices have shown superior results in this respect. Higher rates of pacemaker implantation after TAVI in bicuspid AS do require further investigation. Current data suggest that bicuspid valves should not be a contraindication for TAVI, but future specific trials are needed to support this assertion. PMID:27640030

  4. Effect of acoustic flows on the structure of a constricted glow discharge in argon

    NASA Astrophysics Data System (ADS)

    Saifutdinov, A. I.; Fadeev, S. A.; Saifutdinova, A. A.; Kashapov, N. F.

    2015-11-01

    Numerical experiments on the effect of acoustic flows on the structure of a constricted glow discharge in argon have been performed in the hybrid approximation. The possibility of controlling the combustion regime of the glow discharge with an extended positive column at a high pressure by means of the formation of acoustic flows at the excitation of a standing acoustic wave has been demonstrated. In this case, the discharge transfers from the constricted combustion regime to the diffuse one and becomes stable.

  5. Minimally invasive aortic valve surgery

    PubMed Central

    Castrovinci, Sebastiano; Emmanuel, Sam; Moscarelli, Marco; Murana, Giacomo; Caccamo, Giuseppa; Bertolino, Emanuela Clara; Nasso, Giuseppe; Speziale, Giuseppe; Fattouch, Khalil

    2016-01-01

    Aortic valve disease is a prevalent disorder that affects approximately 2% of the general adult population. Surgical aortic valve replacement is the gold standard treatment for symptomatic patients. This treatment has demonstrably proven to be both safe and effective. Over the last few decades, in an attempt to reduce surgical trauma, different minimally invasive approaches for aortic valve replacement have been developed and are now being increasingly utilized. A narrative review of the literature was carried out to describe the surgical techniques for minimally invasive aortic valve surgery and report the results from different experienced centers. Minimally invasive aortic valve replacement is associated with low perioperative morbidity, mortality and a low conversion rate to full sternotomy. Long-term survival appears to be at least comparable to that reported for conventional full sternotomy. Minimally invasive aortic valve surgery, either with a partial upper sternotomy or a right anterior minithoracotomy provides early- and long-term benefits. Given these benefits, it may be considered the standard of care for isolated aortic valve disease. PMID:27582764

  6. Minimally invasive aortic valve surgery.

    PubMed

    Castrovinci, Sebastiano; Emmanuel, Sam; Moscarelli, Marco; Murana, Giacomo; Caccamo, Giuseppa; Bertolino, Emanuela Clara; Nasso, Giuseppe; Speziale, Giuseppe; Fattouch, Khalil

    2016-09-01

    Aortic valve disease is a prevalent disorder that affects approximately 2% of the general adult population. Surgical aortic valve replacement is the gold standard treatment for symptomatic patients. This treatment has demonstrably proven to be both safe and effective. Over the last few decades, in an attempt to reduce surgical trauma, different minimally invasive approaches for aortic valve replacement have been developed and are now being increasingly utilized. A narrative review of the literature was carried out to describe the surgical techniques for minimally invasive aortic valve surgery and report the results from different experienced centers. Minimally invasive aortic valve replacement is associated with low perioperative morbidity, mortality and a low conversion rate to full sternotomy. Long-term survival appears to be at least comparable to that reported for conventional full sternotomy. Minimally invasive aortic valve surgery, either with a partial upper sternotomy or a right anterior minithoracotomy provides early- and long-term benefits. Given these benefits, it may be considered the standard of care for isolated aortic valve disease. PMID:27582764

  7. Quantitative visualization of asymmetric gas flow in constricted microchannels by using pressure-sensitive paint

    NASA Astrophysics Data System (ADS)

    Huang, Chih-Yung; Chen, Ying-Hsuan; Wan, Shaw-An; Wang, Yu-Chuan

    2016-10-01

    Asymmetric flow in constricted microchannel devices was quantitatively investigated using a pressure-sensitive paint (PSP) technique. For microchannel devices with constriction ratios of 2 : 1 and 5 : 1, detailed pressure maps for the region around the constriction structure were obtained and enabled visualization of the flow field. Symmetric flow was observed in the microchannel device with a constriction ratio of 2 : 1 at the Reynolds number range 2-165. In the microchannel with a constriction ratio of 5 : 1, a deflected flow pattern was clearly identified from PSP measurements at Reynolds numbers exceeding 107. Furthermore, PSP measurements showed a pressure difference of up to 2.5 kPa between the two lateral locations corresponding to y  =  ±0.15 W (W is the microchannel width) downstream of the constriction at a Reynolds number of 279. The pressure difference resulted from asymmetric bifurcation of the flow.

  8. Apical constriction initiates new bud formation during monopodial branching of the embryonic chicken lung.

    PubMed

    Kim, Hye Young; Varner, Victor D; Nelson, Celeste M

    2013-08-01

    Branching morphogenesis sculpts the airway epithelium of the lung into a tree-like structure to conduct air and promote gas exchange after birth. In the avian lung, a series of buds emerges from the dorsal surface of the primary bronchus via monopodial branching to form the conducting airways; anatomically, these buds are similar to those formed by domain branching in the mammalian lung. Here, we show that monopodial branching is initiated by apical constriction of the airway epithelium, and not by differential cell proliferation, using computational modeling and quantitative imaging of embryonic chicken lung explants. Both filamentous actin and phosphorylated myosin light chain were enriched at the apical surface of the airway epithelium during monopodial branching. Consistently, inhibiting actomyosin contractility prevented apical constriction and blocked branch initiation. Although cell proliferation was enhanced along the dorsal and ventral aspects of the primary bronchus, especially before branch formation, inhibiting proliferation had no effect on the initiation of branches. To test whether the physical forces from apical constriction alone are sufficient to drive the formation of new buds, we constructed a nonlinear, three-dimensional finite element model of the airway epithelium and used it to simulate apical constriction and proliferation in the primary bronchus. Our results suggest that, consistent with the experimental results, apical constriction is sufficient to drive the early stages of monopodial branching whereas cell proliferation is dispensable. We propose that initial folding of the airway epithelium is driven primarily by apical constriction during monopodial branching of the avian lung.

  9. Exploring the potential of telmisartan in chronic constriction injury-induced neuropathic pain in rats.

    PubMed

    Jaggi, Amteshwar Singh; Singh, Nirmal

    2011-09-30

    The present study was designed to investigate the potential of telmisartan, an angiotensin AT(1) receptor, in chronic constriction injury-induced neuropathic pain in rats. Four loose ligatures were placed around the sciatic nerve to induce chronic constriction injury and neuropathic pain. Acetone drop, pin-prick, hot plate and paint brush tests were performed to assess cold allodynia; mechanical and heat hyperalgesia; and dynamic mechanical allodynia, respectively along with assessment of spontaneous pain and postural index in terms of foot deformity. The levels of TNF-α were measured in the sciatic nerve as an index of inflammation. Chronic constriction injury was associated with development of cold allodynia; mechanical and heat hyperalgesia; dynamic mechanical allodynia; and spontaneous pain and foot deformity along with rise in the levels of TNF-α. Telmisartan (1, 2, 5 mg/kg, p.o.) was administered for 14 days in chronic constriction injury subjected rats. Administration of telmisartan (2, 5 mg/kg) significantly attenuated chronic constriction injury-induced pain related behavior, foot deformity and rise in TNF-α level. It may be concluded that telmisartan has a potential in attenuating neuropathic pain behavior in chronic constriction injury model which may possibly be attributed to its anti-inflammatory properties. PMID:21741378

  10. Apical constriction initiates new bud formation during monopodial branching of the embryonic chicken lung

    PubMed Central

    Kim, Hye Young; Varner, Victor D.; Nelson, Celeste M.

    2013-01-01

    Branching morphogenesis sculpts the airway epithelium of the lung into a tree-like structure to conduct air and promote gas exchange after birth. In the avian lung, a series of buds emerges from the dorsal surface of the primary bronchus via monopodial branching to form the conducting airways; anatomically, these buds are similar to those formed by domain branching in the mammalian lung. Here, we show that monopodial branching is initiated by apical constriction of the airway epithelium, and not by differential cell proliferation, using computational modeling and quantitative imaging of embryonic chicken lung explants. Both filamentous actin and phosphorylated myosin light chain were enriched at the apical surface of the airway epithelium during monopodial branching. Consistently, inhibiting actomyosin contractility prevented apical constriction and blocked branch initiation. Although cell proliferation was enhanced along the dorsal and ventral aspects of the primary bronchus, especially before branch formation, inhibiting proliferation had no effect on the initiation of branches. To test whether the physical forces from apical constriction alone are sufficient to drive the formation of new buds, we constructed a nonlinear, three-dimensional finite element model of the airway epithelium and used it to simulate apical constriction and proliferation in the primary bronchus. Our results suggest that, consistent with the experimental results, apical constriction is sufficient to drive the early stages of monopodial branching whereas cell proliferation is dispensable. We propose that initial folding of the airway epithelium is driven primarily by apical constriction during monopodial branching of the avian lung. PMID:23824575

  11. Reoperative Aortic Root Replacement in Patients with Previous Aortic Root or Aortic Valve Procedures

    PubMed Central

    Chong, Byung Kwon; Jung, Sung-Ho; Choo, Suk Jung; Chung, Cheol Hyun; Lee, Jae Won; Kim, Joon Bum

    2016-01-01

    Background Generalization of standardized surgical techniques to treat aortic valve (AV) and aortic root diseases has benefited large numbers of patients. As a consequence of the proliferation of patients receiving aortic root surgeries, surgeons are more frequently challenged by reoperative aortic root procedures. The aim of this study was to evaluate the outcomes of redo-aortic root replacement (ARR). Methods We retrospectively reviewed 66 patients (36 male; mean age, 44.5±9.5 years) who underwent redo-ARR following AV or aortic root procedures between April 1995 and June 2015. Results Emergency surgeries comprised 43.9% (n=29). Indications for the redo-ARR were aneurysm (n=12), pseudoaneurysm (n=1), or dissection (n=6) of the residual native aortic sinus in 19 patients (28.8%), native AV dysfunction in 8 patients (12.1%), structural dysfunction of an implanted bioprosthetic AV in 19 patients (28.8%), and infection of previously replaced AV or proximal aortic grafts in 30 patients (45.5%). There were 3 early deaths (4.5%). During follow-up (median, 54.65 months; quartile 1–3, 17.93 to 95.71 months), there were 14 late deaths (21.2%), and 9 valve-related complications including reoperation of the aortic root in 1 patient, infective endocarditis in 3 patients, and hemorrhagic events in 5 patients. Overall survival and event-free survival rates at 5 years were 81.5%±5.1% and 76.4%±5.4%, respectively. Conclusion Despite technical challenges and a high rate of emergency conditions in patients requiring redo-ARR, early and late outcomes were acceptable in these patients. PMID:27525233

  12. Ghostly Ring

    NASA Technical Reports Server (NTRS)

    2008-01-01

    [figure removed for brevity, see original site] Click on image for poster version

    This image shows a ghostly ring extending seven light-years across around the corpse of a massive star. The collapsed star, called a magnetar, is located at the exact center of this image. NASA's Spitzer Space Telescope imaged the mysterious ring around magnetar SGR 1900+14 in infrared light. The magnetar itself is not visible in this image, as it has not been detected at infrared wavelengths (it has been seen in X-ray light).

    Magnetars are formed when a massive giant star ends its life in a supernova explosion, leaving behind a super dense neutron star with an incredibly strong magnetic field. The ring seen by Spitzer could not have formed during the original explosion, as any material as close to the star as the ring would have been disrupted by the supernova shock wave. Scientists suspect that the ring my actually be the edges of a bubble that was hollowed out by an explosive burst from the magnetar in 1998. The very bright region near the center of the image is a cluster of young stars, which may be illuminating the inner edge of the bubble, making it look like a ring in projection.

    This composite image was taken using all three of Spitzer's science instruments. The blue color represents 8-micron infrared light taken by the infrared array camera, green is 16-micron light from the infrared spectograph, and red is 24-micron radiation from the multiband imaging photometer.

  13. Gerbode Defect as a Result of Fungal Aortic Valve Endocarditis.

    PubMed

    Pasrija, Chetan; Mohammed, Isa; Shats, Inna; Hong-Zohlman, Susie; Reoma, Junewai; Mazzeffi, Michael A; Rajagopal, Keshava

    2015-05-01

    A 63-year-old male patient with HIV disease presented with dyspnea and complete heart block, and was found to have aortic valve (AV) endocarditis secondary to Candida parapsilosis infection. Echocardiography demonstrated AV endocarditis and possible aortic root versus subannular abscess with moderate AV regurgitation (AR), a ventricular septal defect (VSD) and possible left ventricular to right atrial shunt (Gerbode defect). Large AV vegetations, subannular abscess with an acquired membranous VSD, Gerbode defect, and tricuspid annular abscess at the insertion of septal leaflet were noted intraoperatively. The patient underwent AV replacement with a stented bioprosthesis, two-sided VSD patch closure, and tricuspid valve (TV) repair with an annuloplasty ring. The left-sided patch closed the VSD and facilitated AV replacement, while the right-sided patch facilitated the TV repair.

  14. Activation of AMP kinase α1 subunit induces aortic vasorelaxation in mice

    PubMed Central

    Goirand, Françoise; Solar, Myriam; Athea, Yoni; Viollet, Benoit; Mateo, Philippe; Fortin, Dominique; Leclerc, Jocelyne; Hoerter, Jacqueline; Ventura-Clapier, Renée; Garnier, Anne

    2007-01-01

    Vasodilatation is a vital mechanism of systemic blood flow regulation that occurs during periods of increased energy demand. The AMP-dependent protein kinase (AMPK) is a serine/threonine kinase that is activated by conditions that increase the AMP-to-ATP ratio, such as exercise and metabolic stress. We hypothesized that AMPK could trigger vasodilatation and participate in blood flow regulation. Rings of thoracic aorta were isolated from C57Bl6 mice and mice deficient in the AMPK catalytic α1 (AMPKα1−/−) or α2 (AMPKα2−/−) subunit and their littermate controls, and mounted in an organ bath. Aortas were preconstricted with phenylephrine (1 μm) and activation of AMPK was induced by addition of increasing concentrations of 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR). AICAR (0.1–3 mm) dose-dependently induced relaxation of precontracted C57BL6, AMPKα1+/+ and α2+/+ aorta (P < 0.001, n = 5–7 per group). This AICAR induced vasorelaxation was not inhibited by the addition of adenosine receptor antagonists. Moreover, when aortic rings were freed of endothelium by gentle rubbing, AICAR still induced aortic ring relaxation, suggesting a direct effect of AICAR on smooth muscle cells. When aortic rings were pretreated with l-NMMA (30 μm) to inhibit nitric oxide synthase activity, AICAR still induced relaxation. Western blot analysis of C57Bl6 mice denuded aorta showed that AMPK was phosphorylated after incubation with AICAR and that AMPKα1 was the main catalytic subunit expressed. Finally, AICAR-induced relaxation of aortic rings was completely abolished in AMPKα1−/− but not AMPKα2−/− mice. Taken together, the results show that activation of AMPKα1 but not AMPKα2 is able to induce aortic relaxation in mice, in an endothelium- and eNOS-independent manner. PMID:17446219

  15. [ENDOVASCULAR ABDOMINAL AORTIC ANEURISM REPAIR].

    PubMed

    Maĭstrenko, D N; Generalov, M I; Tarazov, P G; Zherebtsov, F K; Osovskikh, V V; Ivanov, A S; Oleshchuk, A N; Granov, D A

    2015-01-01

    The authors analyzed the single-center experience of treatment of 72 patients with abdominal aortic aneurisms and severe accompanied pathology. The aneurisms were repaired by stent-grafts. All the patients had abdominal aortic aneurisms with the diameters from 41 to 84 mm against the background of severe somatic pathology. It was a contraindication to planned open surgery. An installation of stent-graft was successful in all 72 follow-ups. It wasn't necessary to use a conversion to open surgery. The follow-up period consisted of 44,6?2,1 months. Control ultrasound and computer tomography studies hadn't revealed an increase of aneurism sack sizes or "eakages". A reduction of abdominal aortic aneurism sizes was noted in 37 patients on 4-5% during first year after operation. The stent-graft implantation extends the possibilities of abdominal aortic aneurism treatment for patients from a high surgical risk group. PMID:26234059

  16. Aortic dissection--an update.

    PubMed

    Mukherjee, Debabrata; Eagle, Kim A

    2005-06-01

    Acute aortic dissection is a medical emergency with high morbidity and mortality requiring emergent diagnosis and therapy. Rapid advances in noninvasive imaging technology have facilitated the early diagnosis of this condition and should be considered in the differential diagnosis of any patient with chest, back, or abdominal pain. Emergent surgery is the treatment for patients with type A dissection while optimal medical therapy is appropriate in patients with uncomplicated type B dissection. Adequate beta-blockade is the cornerstone of medical therapy. Patients who survive acute aortic dissection need long-term medical therapy with beta-blockers and statins and appropriate serial imaging follow-up. Future advances in this field include biomarkers in the early diagnosis of acute aortic dissection and presymptomatic diagnosis with genetic screening. Overall patients with aortic dissection are at high risk for an adverse outcome and need to be managed aggressively in hospital and long term with frequent follow-up. PMID:15973249

  17. Mast cell mediators in citric acid-induced airway constriction of guinea pigs

    SciTech Connect

    Lin, C.-H.; Lai, Y.-L. . E-mail: tiger@ha.mc.ntu.edu.tw

    2005-08-15

    We demonstrated previously that mast cells play an important role in citric acid (CA)-induced airway constriction. In this study, we further investigated the underlying mediator(s) for this type of airway constriction. At first, to examine effects caused by blocking agents, 67 young Hartley guinea pigs were divided into 7 groups: saline + CA; methysergide (serotonin receptor antagonist) + CA; MK-886 (leukotriene synthesis inhibitor) + CA; mepyramine (histamine H{sub 1} receptor antagonist) + CA; indomethacin (cyclooxygenase inhibitor) + CA; cromolyn sodium (mast cell stabilizer) + CA; and compound 48/80 (mast cell degranulating agent) + CA. Then, we tested whether leukotriene C{sub 4} (LTC{sub 4}) or histamine enhances CA-induced airway constriction in compound 48/80-pretreated guinea pigs. We measured dynamic respiratory compliance (Crs) and forced expiratory volume in 0.1 s (FEV{sub 0.1}) during either baseline or recovery period. In addition, we detected histamine level, an index of pulmonary mast cell degranulation, in bronchoalveolar lavage (BAL) samples. Citric acid aerosol inhalation caused decreases in Crs and FEV{sub 0.1}, indicating airway constriction in the control group. This airway constriction was significantly attenuated by MK-886, mepyramine, cromolyn sodium, and compound 48/80, but not by either methysergide or indomethacin. Both LTC{sub 4} and histamine infusion significantly increased the magnitude of CA-induced airway constriction in compound 48/80-pretreated guinea pigs. Citric acid inhalation caused significant increase in histamine level in the BAL sample, which was significantly suppressed by compound 48/80. These results suggest that leukotrienes and histamine originating from mast cells play an important role in CA inhalation-induced noncholinergic airway constriction.

  18. [New aspects in aortic valve disease].

    PubMed

    Tornos, P

    2001-01-01

    Renewed interest for aortic valve disease has evolved in recent years. Aortic valve replacement has become the second most frequent cause of cardiac surgery, following coronary bypass surgery. In addition, the etiologic and physiopathologic knowledge of this disorder has improved. In the present paper we analyze three aspects of the disease which are, at present, the subject of study and controversy: first, we discuss the possible relationship between degenerative aortic stenosis and atherosclerosis; second, the involvement of the aortic root in cases of bicuspid aortic valve; and third, the surgical indications in asymptomatic patients with either aortic stenosis or regurgitation.

  19. Selective serotonin reuptake inhibitor exposure constricts the mouse ductus arteriosus in utero.

    PubMed

    Hooper, Christopher W; Delaney, Cassidy; Streeter, Taylor; Yarboro, Michael T; Poole, Stanley; Brown, Naoko; Slaughter, James C; Cotton, Robert B; Reese, Jeff; Shelton, Elaine L

    2016-09-01

    Use of selective serotonin reuptake inhibitors (SSRIs) is common during pregnancy. Fetal exposure to SSRIs is associated with persistent pulmonary hypertension of the newborn (PPHN); however, a direct link between the two has yet to be established. Conversely, it is well known that PPHN can be caused by premature constriction of the ductus arteriosus (DA), a fetal vessel connecting the pulmonary and systemic circulations. We hypothesized that SSRIs could induce in utero DA constriction. Using isolated vessels and whole-animal models, we sought to determine the effects of two commonly prescribed SSRIs, fluoxetine and sertraline, on the fetal mouse DA. Cannulated vessel myography studies demonstrated that SSRIs caused concentration-dependent DA constriction and made vessels less sensitive to prostaglandin-induced dilation. Moreover, in vivo studies showed that SSRI-exposed mice had inappropriate DA constriction in utero. Taken together, these findings establish that SSRIs promote fetal DA constriction and provide a potential mechanism by which SSRIs could contribute to PPHN. PMID:27371685

  20. Sub-cellular modeling of platelet transport in blood flow through microchannels with constriction.

    PubMed

    Yazdani, Alireza; Karniadakis, George Em

    2016-05-11

    Platelet transport through arterial constrictions is one of the controlling processes influencing their adhesive functions and the formation of thrombi. We perform high-fidelity mesoscopic simulations of blood flow in microchannels with constriction, resembling arterial stenoses. The wall shear rates inside the constrictions reach levels as high as ≈8000 s(-1), similar to those encountered in moderate atherosclerotic plaques. Both red blood cells and platelets are resolved at sub-cellular resolution using the Dissipative Particle Dynamics (DPD) method. We perform a systematic study on the red blood cell and platelet transport by considering different levels of constriction, blood hematocrit and flow rates. We find that higher levels of constriction and wall shear rates lead to significantly enhanced margination of platelets, which may explain the experimental observations of enhanced post-stenosis platelet aggregation. We also observe similar margination effects for stiff particles of spherical shapes such as leukocytes. To our knowledge, such numerical simulations of dense blood through complex geometries have not been performed before, and our quantitative findings could shed new light on the associated physiological processes such as ATP release, plasma skimming, and thrombus formation. PMID:27087267

  1. Vangl2 cooperates with Rab11 and Myosin V to regulate apical constriction during vertebrate gastrulation

    PubMed Central

    Ossipova, Olga; Chuykin, Ilya; Chu, Chih-Wen; Sokol, Sergei Y.

    2015-01-01

    Core planar cell polarity (PCP) proteins are well known to regulate polarity in Drosophila and vertebrate epithelia; however, their functions in vertebrate morphogenesis remain poorly understood. In this study, we describe a role for PCP signaling in the process of apical constriction during Xenopus gastrulation. The core PCP protein Vangl2 is detected at the apical surfaces of cells at the blastopore lip, and it functions during blastopore formation and closure. Further experiments show that Vangl2, as well as Daam1 and Rho-associated kinase (Rock), regulate apical constriction of bottle cells at the blastopore and ectopic constriction of ectoderm cells triggered by the actin-binding protein Shroom3. At the blastopore lip, Vangl2 is required for the apical accumulation of the recycling endosome marker Rab11. We also show that Rab11 and the associated motor protein Myosin V play essential roles in both endogenous and ectopic apical constriction, and might be involved in Vangl2 trafficking to the cell surface. Overexpression of Rab11 RNA was sufficient to partly restore normal blastopore formation in Vangl2-deficient embryos. These observations suggest that Vangl2 affects Rab11 to regulate apical constriction during blastopore formation. PMID:25480917

  2. Essential role for smooth muscle BK channels in alcohol-induced cerebrovascular constriction

    NASA Astrophysics Data System (ADS)

    Liu, Pengchong; Xi, Qi; Ahmed, Abu; Jaggar, Jonathan H.; Dopico, Alejandro M.

    2004-12-01

    Binge drinking is associated with increased risk for cerebrovascular spasm and stroke. Acute exposure to ethanol at concentrations obtained during binge drinking constricts cerebral arteries in several species, including humans, but the mechanisms underlying this action are largely unknown. In a rodent model, we used fluorescence microscopy, patch-clamp electrophysiology, and pharmacological studies in intact cerebral arteries to pinpoint the molecular effectors of ethanol cerebrovascular constriction. Clinically relevant concentrations of ethanol elevated wall intracellular Ca2+ concentration and caused a reversible constriction of cerebral arteries (EC50 = 27 mM; Emax = 100 mM) that depended on voltage-gated Ca2+ entry into myocytes. However, ethanol did not directly increase voltage-dependent Ca2+ currents in isolated myocytes. Constriction occurred because of an ethanol reduction in the frequency (-53%) and amplitude (-32%) of transient Ca2+-activated K+ (BK) currents. Ethanol inhibition of BK transients was caused by a reduction in Ca2+ spark frequency (-49%), a subsarcolemmal Ca2+ signal that evokes the BK transients, and a direct inhibition of BK channel steady-state activity (-44%). In contrast, ethanol failed to modify Ca2+ waves, a major vasoconstrictor mechanism. Selective block of BK channels largely prevented ethanol constriction in pressurized arteries. This study pinpoints the Ca2+ spark/BK channel negative-feedback mechanism as the primary effector of ethanol vasoconstriction.

  3. Video-Assisted Thoracoscopic Division of Vascular Rings

    PubMed Central

    Lee, Jung Hee; Yang, Ji-Hyuk; Jun, Tae-Gook

    2015-01-01

    This study reports our early experience with thoracoscopic division of vascular rings. Three patients were reviewed; their ages at surgery were 25 months, 4 years, and 57 years. All patients were suffering from complete vascular rings involving combinations of the right aortic arch, left ligamentum arteriosum, Kommerell’s diverticulum, and retroesophageal left subclavian artery. The median surgical time was 180.5 minutes, and the patients showed immediate recovery. Three complications, namely chylothorax, transient supraventricular tachycardia, and left vocal cord palsy, were observed. Our early experience indicates that thoracoscopic division of a vascular ring may provide early recovery and could be a promising operative choice. PMID:25705605

  4. Vascular ring diagnosis following respiratory arrest

    PubMed Central

    Robson, Evie Alexandra; Scott, Alison; Chetcuti, Philip; Crabbe, David

    2014-01-01

    Vascular rings can present with non-specific respiratory and/or oesophageal symptoms. Early diagnosis requires a high index of suspicion. This case report describes an uncommon acute presentation of a vascular ring. We report a thriving 14-month-old child with a long history of recurrent wheeze and ‘noisy breathing’. He presented acutely with food bolus impaction in the oesophagus which led to a respiratory arrest. Oesophagoscopy and bronchoscopy suggested vascular ring anomaly. A contrast-enhanced CT scan demonstrated a right-sided aortic arch with left ligamentum arteriosum encircling the oesophagus and airway. The ligament was ligated and divided. At follow-up 6 months later, the infant had mild persistent stridor but was otherwise well. PMID:24895385

  5. Data on the mechanisms underlying succinate-induced aortic contraction.

    PubMed

    Gonzaga, Natália A; Simplicio, Janaina A; Leite, Letícia N; Vale, Gabriel T; Carballido, José M; Alves-Filho, José C; Tirapelli, Carlos R

    2016-12-01

    We describe the mechanisms underlying the vascular contraction induced by succinate. The data presented here are related to the article entitled "Pharmacological characterization of the mechanisms underlying the vascular effects of succinate" (L.N. Leite, N.A. Gonzaga, J.A. Simplicio, G.T. Vale, J.M. Carballido, J.C. Alves-Filho, C.R. Tirapelli, 2016) [1]. Succinate acts as a signaling molecule by binding to a G-protein-coupled receptor termed GPR91, "Citric acid cycle intermediates as ligands for orphan G-protein-coupled receptors" (W. He, F.J. Miao, D.C. Lin, R.T. Schwandner, Z. Wang, J. Gao, J.L. Chen, H. Tian, L. Ling, 2004) [2]. Here we include data on the contractile effect of succinate in the aorta. Succinate contracted both endothelium-intact and endothelium-denuded aortic rings isolated from male Wistar rats or C57BL/6 mice. Succinate was less effective at inducing contraction in arteries isolated from GPR91-deficient mice, when compared to its vascular effect in aortas from wild type mice. SB203508 (p38MAK inhibitor), SP600125 (JNK inhibitor) and Y27632 (Rho-kinase inhibitor) reduced succinate-induced contraction in both endothelium-intact and endothelium-denuded rat aortic rings, while PD98059 (ERK1/2 inhibitor) did not affect succinate-induced contraction. The contractile response induced by succinate on endothelium-intact and endothelium-denuded rat aortic rings was reduced by indomethacin (non-selective cyclooxygenase inhibitor), H7 (protein kinase C inhibitor), verapamil (Ca(2+) channel blocker) and tiron (superoxide anion scavenger). PMID:27656674

  6. Data on the mechanisms underlying succinate-induced aortic contraction.

    PubMed

    Gonzaga, Natália A; Simplicio, Janaina A; Leite, Letícia N; Vale, Gabriel T; Carballido, José M; Alves-Filho, José C; Tirapelli, Carlos R

    2016-12-01

    We describe the mechanisms underlying the vascular contraction induced by succinate. The data presented here are related to the article entitled "Pharmacological characterization of the mechanisms underlying the vascular effects of succinate" (L.N. Leite, N.A. Gonzaga, J.A. Simplicio, G.T. Vale, J.M. Carballido, J.C. Alves-Filho, C.R. Tirapelli, 2016) [1]. Succinate acts as a signaling molecule by binding to a G-protein-coupled receptor termed GPR91, "Citric acid cycle intermediates as ligands for orphan G-protein-coupled receptors" (W. He, F.J. Miao, D.C. Lin, R.T. Schwandner, Z. Wang, J. Gao, J.L. Chen, H. Tian, L. Ling, 2004) [2]. Here we include data on the contractile effect of succinate in the aorta. Succinate contracted both endothelium-intact and endothelium-denuded aortic rings isolated from male Wistar rats or C57BL/6 mice. Succinate was less effective at inducing contraction in arteries isolated from GPR91-deficient mice, when compared to its vascular effect in aortas from wild type mice. SB203508 (p38MAK inhibitor), SP600125 (JNK inhibitor) and Y27632 (Rho-kinase inhibitor) reduced succinate-induced contraction in both endothelium-intact and endothelium-denuded rat aortic rings, while PD98059 (ERK1/2 inhibitor) did not affect succinate-induced contraction. The contractile response induced by succinate on endothelium-intact and endothelium-denuded rat aortic rings was reduced by indomethacin (non-selective cyclooxygenase inhibitor), H7 (protein kinase C inhibitor), verapamil (Ca(2+) channel blocker) and tiron (superoxide anion scavenger).

  7. Aortic or Mitral Valve Replacement With the Biocor and Biocor Supra

    ClinicalTrials.gov

    2016-03-09

    Aortic Valve Insufficiency; Aortic Valve Regurgitation; Aortic Valve Stenosis; Aortic Valve Incompetence; Mitral Valve Insufficiency; Mitral Valve Regurgitation; Mitral Valve Stenosis; Mitral Valve Incompetence

  8. Value of reference tracings in diagnosis and assessment of constrictive epi- and pericarditis

    PubMed Central

    Kesteloot, H.; Denef, B.

    1970-01-01

    Reference tracings are of great value in the diagnosis and assessment of constrictive pericarditis. The Q-h interval in the jugular venous pulse tracing is strongly correlated with the mean right atrial pressure (r=0·91). The left ventricular ejection time, the Q-A2 interval, and the Q-h interval are independent during atrial fibrillation from the preceding diastolic filling interval. This differentiates constrictive pericarditis from valvular heart disease. Cases with haemodynamically significant constrictive epicarditis are characterized by a rapid evolution, absence of pericardial calcification and absence of an early diastolic filling sound, a dominant a wave in the jugular venous pulse tracing, and a high early diastolic ventricular pressure. The haemodynamic behaviour is similar to that found in cases with myocardial fibrosis. Images PMID:5470050

  9. Apical domain polarization localizes actin-myosin activity to drive ratchet-like apical constriction.

    PubMed

    Mason, Frank M; Tworoger, Michael; Martin, Adam C

    2013-08-01

    Apical constriction promotes epithelia folding, which changes tissue architecture. During Drosophila gastrulation, mesoderm cells exhibit repeated contractile pulses that are stabilized such that cells apically constrict like a ratchet. The transcription factor Twist is required to stabilize cell shape. However, it is unknown how Twist spatially coordinates downstream signals to prevent cell relaxation. We find that during constriction, Rho-associated kinase (Rok) is polarized to the middle of the apical domain (medioapical cortex), separate from adherens junctions. Rok recruits or stabilizes medioapical myosin II (Myo-II), which contracts dynamic medioapical actin cables. The formin Diaphanous mediates apical actin assembly to suppress medioapical E-cadherin localization and form stable connections between the medioapical contractile network and adherens junctions. Twist is not required for apical Rok recruitment, but instead polarizes Rok medioapically. Therefore, Twist establishes radial cell polarity of Rok/Myo-II and E-cadherin and promotes medioapical actin assembly in mesoderm cells to stabilize cell shape fluctuations.

  10. Integrins regulate apical constriction via microtubule stabilization in the Drosophila eye disc epithelium.

    PubMed

    Fernandes, Vilaiwan M; McCormack, Kasandra; Lewellyn, Lindsay; Verheyen, Esther M

    2014-12-24

    During morphogenesis, extracellular signals trigger actomyosin contractility in subpopulations of cells to coordinate changes in cell shape. To illuminate the link between signaling-mediated tissue patterning and cytoskeletal remodeling, we study the progression of the morphogenetic furrow (MF), the wave of apical constriction that traverses the Drosophila eye imaginal disc preceding photoreceptor neurogenesis. Apical constriction depends on actomyosin contractility downstream of the Hedgehog (Hh) and bone morphogenetic protein (BMP) pathways. We identify a role for integrin adhesion receptors in MF progression. We show that Hh and BMP regulate integrin expression, the loss of which disrupts apical constriction and slows furrow progression; conversely, elevated integrins accelerate furrow progression. We present evidence that integrins regulate MF progression by promoting microtubule stabilization, since reducing microtubule stability rescues integrin-mediated furrow acceleration. Thus, integrins act as a genetic link between tissue-level signaling events and morphological change at the cellular level, leading to morphogenesis and neurogenesis in the eye.

  11. Effusive-constrictive pericarditis as the manifestation of an unexpected diagnosis.

    PubMed

    Marta, Liliana; Alves, Miguel; Peres, Marisa; Ferreira, Ricardo; Ferreira, Hugo; Leal, Margarida; Nobre, Ângelo

    2015-01-01

    Constrictive pericarditis is a clinical condition characterized by the appearance of signs and symptoms of right heart failure due to loss of pericardial compliance. Cardiac surgery is now one of the most frequent causes in developed countries, while tuberculosis remains the most prevalent cause in developing countries. Malignancy is a rare cause but usually has a poor prognosis. The diagnosis of constrictive pericarditis remains a clinical challenge and requires a combination of noninvasive diagnostic methods (echocardiography, cardiac magnetic resonance and computed tomography); in some cases, cardiac catheterization is needed to confirm the diagnosis. The authors present the case of a 51-year-old man, hospitalized due to cardiac tamponade. Diagnostic investigation was suggestive of tuberculous etiology. Despite directed medical therapy, the patient developed effusive-constrictive physiology. He underwent pericardiectomy and anatomopathologic study suggested a neoplastic etiology. The patient died in the postoperative period from biventricular failure.

  12. Effects of calcium antagonists on isolated bovine cerebral arteries: inhibition of constriction and calcium-45 uptake induced by potassium or serotonin

    SciTech Connect

    Wendling, W.W.; Harakal, C.

    1987-05-01

    The purpose of this study was to determine the mechanisms by which organic calcium channel blockers inhibit cerebral vasoconstriction. Isolated bovine middle cerebral arteries were cut into rings to measure contractility or into strips to measure radioactive calcium (/sup 45/Ca) influx and efflux. Calcium channel blockers (10(-5) M verapamil or 3.3 X 10(-7) M nifedipine) and calcium-deficient solutions all produced near-maximal inhibition of both potassium- and serotonin-induced constriction. In calcium-deficient solutions containing potassium or serotonin, verapamil and nifedipine each blocked subsequent calcium-induced constriction in a competitive manner. Potassium and serotonin significantly increased /sup 45/Ca uptake into cerebral artery strips during 5 minutes of /sup 45/Ca loading; for potassium /sup 45/Ca uptake increased from 62 to 188 nmol/g, and for serotonin from 65 to 102 nmol/g. Verapamil or nifedipine had no effect on basal /sup 45/Ca uptake but significantly blocked the increase in /sup 45/Ca uptake induced by potassium or serotonin. Potassium, and to a lesser extent serotonin, each induced a brief increase in the rate of /sup 45/Ca efflux into calcium-deficient solutions. Verapamil or nifedipine had no effect on basal or potassium-stimulated /sup 45/Ca efflux. The results demonstrate that verapamil and nifedipine block /sup 45/Ca uptake through both potential-operated (potassium) and receptor-operated (serotonin) channels in bovine middle cerebral arteries.

  13. Ascending Aortic Slide for Interrupted Aortic Arch Repair.

    PubMed

    Urencio, Miguel; Dodge-Khatami, Ali; Greenleaf, Chris E; Aru, Giorgio; Salazar, Jorge D

    2016-09-01

    For repair of interrupted aortic arch, unfavorable anatomy challenges a tension-free anastomosis. We describe a useful alternative surgical technique used in five neonates/infants, involving splitting the ascending aorta from the sinotubular junction to the arch origin, leftward and posterior "sliding" of the flap with anastomosis to the distal arch creating a native tissue bridge, and reconstruction with a patch. With wide interruption gaps between proximal and distal aortic portions, the ascending aortic slide is a safe and reproducible technique, providing a tension-free native tissue bridge with potential for growth, and a scaffold for patch augmentation in biventricular hearts, or for Norwood stage I in univentricular palliation. PMID:27587504

  14. Surgical Repair of Retrograde Type A Aortic Dissection after Thoracic Endovascular Aortic Repair

    PubMed Central

    Kim, Chang-Young; Kim, Yeon Soo; Ryoo, Ji Yoon

    2014-01-01

    It is expected that the stent graft will become an alternative method for treating aortic diseases or reducing the extent of surgery; therefore, thoracic endovascular aortic repair has widened its indications. However, it can have rare but serious complications such as paraplegia and retrograde type A aortic dissection. Here, we report a surgical repair of retrograde type A aortic dissection that was performed after thoracic endovascular aortic repair. PMID:24570865

  15. Abdominal aortic feminism.

    PubMed

    Mortimer, Alice Emily

    2014-11-14

    A 79-year-old woman presented to a private medical practice 2 years previously for an elective ultrasound screening scan. This imaging provided the evidence for a diagnosis of an abdominal aortic aneurysm (AAA) to be made. Despite having a number of recognised risk factors for an AAA, her general practitioner at the time did not follow the guidance set out by the private medical professional, that is, to refer the patient to a vascular specialist to be entered into a surveillance programme and surgically evaluated. The patient became symptomatic with her AAA, was admitted to hospital and found to have a tender, symptomatic, 6 cm leaking AAA. She consented for an emergency open AAA repair within a few hours of being admitted to hospital, despite the 50% perioperative mortality risk. The patient spent 4 days in intensive care where she recovered well. She was discharged after a 12 day hospital stay but unfortunately passed away shortly after her discharge from a previously undiagnosed gastric cancer.

  16. Nitric oxide alterations following acute ductal constriction in the fetal lamb: a role for superoxide.

    PubMed

    Hsu, Jong-Hau; Oishi, Peter; Wiseman, Dean A; Hou, Yali; Chikovani, Omar; Datar, Sanjeev; Sajti, Eniko; Johengen, Michael J; Harmon, Cynthia; Black, Stephen M; Fineman, Jeffrey R

    2010-06-01

    Acute partial compression of the fetal ductus arteriosus (DA) results in an initial abrupt increase in pulmonary blood flow (PBF), which is followed by a significant reduction in PBF to baseline values over the ensuing 2-4 h. We have previously demonstrated that this potent vasoconstricting response is due, in part, to an endothelin-1 (ET-1)-mediated decrease in nitric oxide synthase (NOS) activity. In addition, in vitro data demonstrate that ET-1 increases superoxide levels in pulmonary arterial smooth muscle cells and that oxidative stress alters NOS activity. Therefore, the objectives of this study were to determine the potential role of superoxide in the alterations of hemodynamics and NOS activity following acute ductal constriction in the late-gestation fetal lamb. Eighteen anesthetized near-term fetal lambs were instrumented, and a lung biopsy was performed. After a 48-h recovery, acute constriction of the DA was performed by inflating a vascular occluder. Polyethylene glycol-superoxide dismutase (PEG-SOD; 1,000-1,500 units/kg, n = 7) or PEG-alone (vehicle control group, n = 5) was injected into the pulmonary artery before ductal constriction. Six animals had a sham operation. In PEG-alone-treated lambs, acute ductal constriction rapidly decreased pulmonary vascular resistance (PVR) by 88%. However, by 4 h, PVR returned to preconstriction baseline. This vasoconstriction was associated with an increase in lung superoxide levels (82%), a decrease in total NOS activity (50%), and an increase in P-eNOS-Thr495 (52%) (P < 0.05). PEG-SOD prevented the increase of superoxide after ductal constriction, attenuated the vasoconstriction, preserved NOS activity, and increased P-eNOS Ser1177 (307%, P < 0.05). Sham procedure induced no changes. These data suggest that an acute decrease in NOS activity that is mediated, in part, by increased superoxide levels, and alterations in the phosphorylation status of the endothelial NOS isoform, underlie the pulmonary vascular

  17. Pressure-induced constriction is inhibited in a mouse model of reduced betaENaC.

    PubMed

    VanLandingham, Lauren G; Gannon, Kimberly P; Drummond, Heather A

    2009-09-01

    Recent studies suggest certain epithelial Na(+) channel (ENaC) proteins may be components of mechanosensitive ion channel complexes in vascular smooth muscle cells that contribute to pressure-induced constriction in middle cerebral arteries (MCA). However, the role of a specific ENaC protein, betaENaC, in pressure-induced constriction of MCAs has not been determined. The goal of this study was to determine whether pressure-induced constriction in the MCA is altered in a mouse model with reduced levels of betaENaC. Using quantitative immunofluorescence, we found whole cell betaENaC labeling in cerebral vascular smooth muscle cells (VSMCs) was suppressed 46% in betaENaC homozygous mutant (m/m) mice compared with wild-type littermates (+/+). MCAs from betaENaC +/+ and m/m mice were isolated and placed in a vessel chamber for myographic analysis. Arteries from betaENaC+/+ mice constricted to stepwise increases in perfusion pressure and developed maximal tone of 10 +/- 2% at 90 mmHg (n = 5). In contrast, MCAs from betaENaC m/m mice developed significantly less tone (4 +/- 1% at 90 mmHg, n = 5). Vasoconstrictor responses to KCl (4-80 mM) were identical between genotypes and responses to phenylephrine (10(-7)-10(-4) M) were marginally altered, suggesting that reduced levels of VSMC betaENaC specifically inhibit pressure-induced constriction. Our findings indicate betaENaC is required for normal pressure-induced constriction in the MCA and provide further support for the hypothesis that betaENaC proteins are components of a mechanosensor in VSMCs. PMID:19553501

  18. Mechanotransduction in mechanically coupled pulsating cells: transition to collective constriction and mesoderm invagination simulation

    NASA Astrophysics Data System (ADS)

    Driquez, Benjamin; Bouclet, Adrien; Farge, Emmanuel

    2011-12-01

    Embryonic differentiation and morphogenesis require the coordination of the cascades of gene product expression with the morphogenetic sequence of development. The influence of mechanical deformations driven by morphogenetic movements on biochemical activities was recently revealed by the existence of mechanotransduction processes in development, involving both gene transcription and protein behaviour. In the early Drosophila embryo, apical stabilization of Myosin-II leading to mesoderm invagination at the onset of gastrulation was proposed to be triggered in response to the activation of the Fog mechanotransduction pathway by the Snail-dependent active mechanical oscillations of cell apex sizes. Here we simulate the mesoderm as mechanically coupled cells, with pulsatile forces of constriction at the cell level mimicking Snail-dependent active fluctuations of apexes. We define a critical apex diameter triggering active constriction that mimics the activation of the Fog mechanotransduction pathway leading to cell constriction. We find that collective movements trigger the dynamical transition to constriction predicting the experimental dynamics of mesoderm cell apex size decrease with a modulus of contractility four times higher than the passive modulus of elastic deformation of the cells. The contraction wave is activated in a pulsation frequency-dependent process, and propagates at multicellular scales through local cell-cell mechanical interactions. By reproducing the pattern of Snail and Fog gene product protein expression in a simulation of ventral cells, the model phenocopies the pattern of Myo-II apical stabilization, and the dynamic pattern of constriction that initiates along a central sub-domain of the mesoderm. We propose that multicellular mechanical collective effects couple with mechanotransduction biochemical mechanisms to trigger the transition of collective coordinated constriction, through a mechano-genetic process ensuring efficient and regular

  19. Mechanotransduction in mechanically coupled pulsating cells: transition to collective constriction and mesoderm invagination simulation.

    PubMed

    Driquez, Benjamin; Bouclet, Adrien; Farge, Emmanuel

    2011-12-01

    Embryonic differentiation and morphogenesis require the coordination of the cascades of gene product expression with the morphogenetic sequence of development. The influence of mechanical deformations driven by morphogenetic movements on biochemical activities was recently revealed by the existence of mechanotransduction processes in development, involving both gene transcription and protein behaviour. In the early Drosophila embryo, apical stabilization of Myosin-II leading to mesoderm invagination at the onset of gastrulation was proposed to be triggered in response to the activation of the Fog mechanotransduction pathway by the Snail-dependent active mechanical oscillations of cell apex sizes. Here we simulate the mesoderm as mechanically coupled cells, with pulsatile forces of constriction at the cell level mimicking Snail-dependent active fluctuations of apexes. We define a critical apex diameter triggering active constriction that mimics the activation of the Fog mechanotransduction pathway leading to cell constriction. We find that collective movements trigger the dynamical transition to constriction predicting the experimental dynamics of mesoderm cell apex size decrease with a modulus of contractility four times higher than the passive modulus of elastic deformation of the cells. The contraction wave is activated in a pulsation frequency-dependent process, and propagates at multicellular scales through local cell-cell mechanical interactions. By reproducing the pattern of Snail and Fog gene product protein expression in a simulation of ventral cells, the model phenocopies the pattern of Myo-II apical stabilization, and the dynamic pattern of constriction that initiates along a central sub-domain of the mesoderm. We propose that multicellular mechanical collective effects couple with mechanotransduction biochemical mechanisms to trigger the transition of collective coordinated constriction, through a mechano-genetic process ensuring efficient and regular

  20. Open aortic surgery after thoracic endovascular aortic repair.

    PubMed

    Coselli, Joseph S; Spiliotopoulos, Konstantinos; Preventza, Ourania; de la Cruz, Kim I; Amarasekara, Hiruni; Green, Susan Y

    2016-08-01

    In the last decade, thoracic endovascular aortic aneurysm repair (TEVAR) has emerged as an appealing alternative to the traditional open aortic aneurysm repair. This is largely due to generally improved early outcomes associated with TEVAR, including lower perioperative mortality and morbidity. However, it is relatively common for patients who undergo TEVAR to need a secondary intervention. In select circumstances, these secondary interventions are performed as an open procedure. Although it is difficult to assess the rate of open repairs after TEVAR, the rates in large series of TEVAR cases (>300) have ranged from 0.4 to 7.9 %. Major complications of TEVAR that typically necessitates open distal aortic repair (i.e., repair of the descending thoracic or thoracoabdominal aorta) include endoleak (especially type I), aortic fistula, endograft infection, device collapse or migration, and continued expansion of the aneurysm sac. Conversion to open repair of the distal aorta may be either elective (as for many endoleaks) or emergent (as for rupture, retrograde complicated dissection, malperfusion, and endograft infection). In addition, in select patients (e.g., those with a chronic aortic dissection), unrepaired sections of the aorta may progressively dilate, resulting in the need for multiple distal aortic repairs. Open repairs after TEVAR can be broadly classified as full extraction, partial extraction, or full salvage of the stent-graft. Although full and partial stent-graft extraction imply failure of TEVAR, such failure is generally absent in cases where the stent-graft can be fully salvaged. We review the literature regarding open repair after TEVAR and highlight operative strategies.

  1. Peptide-induced prostaglandin biosynthesis in the renal-vein-constricted kidney

    PubMed Central

    Myers, Stuart I.; Zipser, Robert; Needleman, Philip

    1981-01-01

    The ipsilateral kidney was removed from a rabbit 48h after unilateral partial renal-vein-constriction and was perfused with Krebs–Henseleit media at 37°C. Hourly administration of a fixed dose of bradykinin to the renal-vein-constricted kidney demonstrated a marked time-dependent increase in the release of bioassayable prostaglandin E2 and thromboxane A2 into the venous effluent as compared with the response of the contralateral control kidney. The renal-vein-constricted kidney produced up to 60 times more prostaglandin E2 in response to bradykinin after 6h of perfusion as compared with the contralateral kidney; thromboxane A2 was not demonstratable in the contralateral kidney. Inhibition of protein synthesis de novo in the perfused renal-vein-constricted kidney with cycloheximide lessened the hormone-stimulated increase in prostaglandin E2 by 94% and in thromboxane A2 by 90% at 6h of perfusion. Covalent acetylation of the renal cyclo-oxygenase by prior oral administration of aspirin to the rabbit inhibited initial bradykinin-stimulated prostaglandin E2 biosynthesis 71% at 1h of perfusion. However, there was total recovery from aspirin in the renal-vein-constricted kidney by 2h of perfusion after bradykinin stimulation. Total cyclo-oxygenase activity as measured by [14C]arachidonate metabolism to labelled prostaglandins by renal cortical and renal medullary microsomal fractions prepared from 6h-perfused kidneys demonstrated that renal-vein-constricted kidney-cortical cyclo-oxygenase activity was significantly greater than the contralateral-kidney-cortical conversion, whereas medullary arachidonate metabolism was comparable in both the renal-vein-constricted kidney and contralateral kidney. These data suggest that perfusion of a renal-vein-constricted kidney initiates a time-dependent induction of synthesis of prostaglandin-producing enzymes, which appear to be primarily localized in the renal cortex. The presence of the synthetic capacity to generate very potent

  2. Gas-dynamic disturbances created by surface dielectric barrier discharge in the constricted mode

    NASA Astrophysics Data System (ADS)

    Moralev, I.; Boytsov, S.; Kazansky, P.; Bityurin, V.

    2014-05-01

    Three-dimensional structure of the gas-dynamic disturbances, created by surface dielectric barrier discharge in a constricted (saturated) mode, was analyzed simultaneously with the discharge morphology. Discharge was created in the still air under normal conditions. Flow visualization was performed by shadowgraphy and stereo-PIV technique. The wall-normal jets with the origins located in between the positions of the constricted filaments are found. Velocity magnitude in the wall-normal direction is comparable with the tangential component. Flow structure is similar to the one created by the serpentine actuator.

  3. Actomyosin Ring Formation and Tension Generation in Eukaryotic Cytokinesis.

    PubMed

    Cheffings, Thomas H; Burroughs, Nigel J; Balasubramanian, Mohan K

    2016-08-01

    Cell division facilitated by a contractile ring is an almost universal feature across all branches of cellular life, with the notable exception of higher plants. In all organisms that use a contractile ring for cell division, the process of cytokinesis can be divided into four distinct stages. Firstly, the cell needs to specify a location at which to place the cell division ring to ensure proper separation of the cell contents into two daughter cells. Secondly, the cell needs to be able to transport all the necessary components to this region, and construct the cell division ring reliably and efficiently. Thirdly, the cell division ring needs to generate contractile stress in a regulated manner, to physically cleave the mother cell into two daughter cells. Finally, the ring must be disassembled to allow for the final abscission and separation of the daughter cells. In this review, we will discuss some of the proposed mechanisms by which eukaryotic cells are able to complete the first three of these stages. While there is a good understanding of the mechanisms of division site specification in most organisms, and the mechanisms of actomyosin ring formation are well studied in fission and budding yeast, there is relatively poor understanding of how actomyosin interactions are able to generate contractile stresses during ring constriction, although a number of models have been proposed. We also discuss a number of myosin motor-independent mechanisms that have been proposed to generate contractile stress in various organisms. PMID:27505246

  4. Aortic regurgitation caused by rupture of the abnormal fibrous band between the aortic valve and aortic wall.

    PubMed

    Minami, Hiroya; Asada, Tatsuro; Gan, Kunio; Yamada, Akitoshi; Sato, Masanobu

    2011-07-01

    This report documents the sudden onset of aortic regurgitation (AR) by an exceptional cause. A 68-year-old woman suddenly experienced general fatigue, and AR was diagnosed. One year later, we performed aortic valve replacement. At surgery, three aortic cusps with a larger noncoronary cusp had prolapsed along with a free-floating fibrous band that had previously anchored the cusp to the aortic wall. Its rupture had induced the sudden onset of AR. There was no sign of infectious endocarditis. We performed successful aortic valve replacement. PMID:21751110

  5. [MINIMALLY INVASIVE AORTIC VALVE REPLACEMENT].

    PubMed

    Tabata, Minoru

    2016-03-01

    Minimally invasive aortic valve replacement (MIAVR) is defined as aortic valve replacement avoiding full sternotomy. Common approaches include a partial sternotomy right thoracotomy, and a parasternal approach. MIAVR has been shown to have advantages over conventional AVR such as shorter length of stay and smaller amount of blood transfusion and better cosmesis. However, it is also known to have disadvantages such as longer cardiopulmonary bypass and aortic cross-clamp times and potential complications related to peripheral cannulation. Appropriate patient selection is very important. Since the procedure is more complex than conventional AVR, more intensive teamwork in the operating room is essential. Additionally, a team approach during postoperative management is critical to maximize the benefits of MIAVR.

  6. Pseudoaneurysm of the aortic arch

    PubMed Central

    Lu, Yuan-Qiang; Yao, Feng; Shang, An-Dong; Pan, Jian

    2016-01-01

    Abstract Background: Pseudoaneurysm of the aortic arch is uncommonly associated with cancer, and is extremely rare in pulmonary cancer. Here, we report an unusual and successfully treated case of aortic arch pseudoaneurysm in a male patient with lung squamous cell carcinoma. Methods: A 64-year-old male patient was admitted to the Emergency Department, presenting with massive hemoptysis (>500 mL blood during the 12 hours prior to treatment). The diagnosis of aortic arch pseudoaneurysm was confirmed after inspection of computed tomographic angiography and three-dimensional reconstruction. We processed the immediate endovascular stent-grafting for this patient. Results: This patient recovered with no filling or enlargement of the pseudoaneurysm, no episodes of hemoptysis, and no neurological complications during the 4-week follow-up period. Conclusion: Herein, we compare our case with other cancer-related pseudoaneurysms in the medical literature and summarize the clinical features and treatment of this unusual case. PMID:27495079

  7. Ringing wormholes

    SciTech Connect

    Konoplya, R.A.; Molina, C.

    2005-06-15

    We investigate the response of traversable wormholes to external perturbations through finding their characteristic frequencies and time-domain profiles. The considered solution describes traversable wormholes between the branes in the two brane Randall-Sundrum model and was previously found within Einstein gravity with a conformally coupled scalar field. The evolution of perturbations of a wormhole is similar to that of a black hole and represents damped oscillations (ringing) at intermediately late times, which are suppressed by power-law tails (proportional to t{sup -2} for monopole perturbations) at asymptotically late times.

  8. Mosaic ring chromosome 6 in an infant with significant patent ductus arteriosus and multiple congenital anomalies.

    PubMed

    Lee, Seung Jae; Han, Dong Kyun; Cho, Hwa Jin; Cho, Young Kuk; Ma, Jae Sook

    2012-08-01

    The clinical features of ring chromosome 6 include central nervous system anomalies, growth retardation, facial dysmorphism and other congenital anomalies. Ring chromosome 6 occurs rarely and manifests as various phenotypes. We report the case of mosaic ring chromosome 6 by conventional karyotyping in a 7-day-old male infant diagnosed with a large patent ductus arteriosus (PDA) with hypoplasia of aortic valve and aortic arch. These have not been previously reported with ring chromosome 6. He recovered from heart failure symptoms after ligation of the PDA. He showed infantile failure to thrive and delayed milestone in a follow-up evaluation. To the best of our knowledge, this is the first report of a Korean individual with ring chromosome 6 and hemodynamically significant PDA.

  9. Abdominal aortic aneurysms: case report

    PubMed Central

    Hadida, Camille; Rajwani, Moez

    1998-01-01

    A 71-year-old male presented to a chiropractic clinic with subacute low back pain. While the pain appeared to be mechanical in nature, radiographic evaluation revealed an abdominal aortic aneurysm, which required the patient to have vascular surgery. This case report illustrates the importance of the history and physical examination in addition to a thorough knowledge of the features of abdominal aortic aneurysms. The application of spinal manipulative therapy in patients with (AAA) is also discussed. ImagesFigure 1Figure 2Figure 3

  10. Aortic and other arterial injuries.

    PubMed Central

    Hardy, J D; Raju, S; Neely, W A; Berry, D W

    1975-01-01

    Three hundred sixty arterial injuries in 353 patients are reviewed. They covered a wide spectrum of injuries and included 36 aortic injuries and 19 cases of carotid truama. The mortality rate of 12% was in large part due to aortic injuries. Shock was the predominant cause of death. Infection was the most frequent non-fatal complication. Pulmonary complications were surprisingly uncommon. With methods and techniques discussed in the paper, 90% satisfactory end results were achieved. The amputation rate was 6% where extremity injuries were involved. Images Fig. 11. Fig. 13. PMID:1130881

  11. Septins promote F-actin ring formation by crosslinking actin filaments into curved bundles.

    PubMed

    Mavrakis, Manos; Azou-Gros, Yannick; Tsai, Feng-Ching; Alvarado, José; Bertin, Aurélie; Iv, Francois; Kress, Alla; Brasselet, Sophie; Koenderink, Gijsje H; Lecuit, Thomas

    2014-04-01

    Animal cell cytokinesis requires a contractile ring of crosslinked actin filaments and myosin motors. How contractile rings form and are stabilized in dividing cells remains unclear. We address this problem by focusing on septins, highly conserved proteins in eukaryotes whose precise contribution to cytokinesis remains elusive. We use the cleavage of the Drosophila melanogaster embryo as a model system, where contractile actin rings drive constriction of invaginating membranes to produce an epithelium in a manner akin to cell division. In vivo functional studies show that septins are required for generating curved and tightly packed actin filament networks. In vitro reconstitution assays show that septins alone bundle actin filaments into rings, accounting for the defects in actin ring formation in septin mutants. The bundling and bending activities are conserved for human septins, and highlight unique functions of septins in the organization of contractile actomyosin rings.

  12. Vascular rings: a radiological review of anatomical variations

    PubMed Central

    Ganie, Iqbal Siddi; Amod, Khatija; Reddy, Darshan

    2016-01-01

    Summary Background The imaging modalities used to diagnose vascular rings have evolved over time, from basic radiographic studies to advanced cross-sectional imaging. The goal of preoperative imaging is to provide the surgeon with an accurate representation of the ring configuration so that the surgical approach may be planned. Methods We conducted a review of all patients with vascular rings who underwent surgery at Inkosi Albert Luthuli Central Hospital, Durban, South Africa from 1 July 2008 to 1 July 2013. Results Eight patients were diagnosed with vascular rings. Seven patients had an abnormal plain chest radiograph (right aortic arch, tracheal narrowing, or abnormal mediastinal silhouette), while in six patients the contrast oesophagogram demonstrated a fixed extrinsic oesophageal indentation. Computed tomography angiography confirmed the pathology in all cases, with six double aortic arches and two right aortic arches with aberrant left subclavian artery and left ligamentum arteriosum. Conclusions We advocate a diagnostic imaging algorithm consisting of plain chest radiography, contrast oesophagogram and computed tomography angiography prior to surgery. Magnetic resonance imaging may provide an alternative axial imaging modality depending on institutional preference. PMID:26523459

  13. [Quadricuspid Aortic Valve: Report of a Case].

    PubMed

    Ryugo, Masahiro; Takasaki, Taiichi

    2016-02-01

    A 69-year-old woman with general fatigue was admitted to our hospital for further examination of mediastinal lymph node swelling. Mediastinal lymph node sampling was planned. Preoperative transthoracic echocardiography revealed severe aortic regurgitation, and aortic valve replacement combined with mediastinal lymph node sampling was performed. Following lymph node sampling, the ascending aorta was opened, and the aortic valve was found to be quadricuspid. An accessory cusp was existed between the left coronary cusp and the non coronary cusp. Aortic valve replacement was successfully performed. A quadricuspid aortic valve is a very rare anomaly. PMID:27075156

  14. [Remote results of reimplantation of the aortic valve in patients with ascending aortic aneurysm accompanied by aortic insufficiency].

    PubMed

    Cherniavskiĭ, A M; Al'sov, S A; Sirota, D A; Khvan, D S; Liashenko, M M; Ponomarev, D N; Kadyrbaev, D Zh

    2015-01-01

    Valve-sparing operations on the aorta has recently been gaining ever increasing popularity due to more detailed study of physiology of the aortic root, as well as promising mid- and long-term results. The world practice uses various techniques making it possible to remove both ascending aortic aneurysm and aortic valve insufficiency. The authors herein describe and analyse their experience in performing reimplantation of the aortic valve in patients with ascending aortic aneurysm and concomitant aortic insufficiency. Specialists of the clinic of the Novosibirsk Scientific Research Institute for Circulatory Pathology during the period from 2003 to 2013 performed a total of 77 operations of reimplantation of the aortic valve in patients with ascending aortic aneurysm and pronounced aortic valve insufficiency. The majority of patients were men (57 males and 20 females), mean age 53.1±12.2 years (range 21-72). 80% of cases had NYHA functional class II-III circulatory insufficiency (degree 2.3±0.7). Preoperative examination revealed in the majority of patients (97.4%) moderate-to-severe aortic valve insufficiency and ascending aortic aneurysm. All patients underwent reimplantation of the aortic valve. The duration of artificial circulation amounted to 202.4±33 minutes, with the average time of aortic occlusion being 164±28 min. Accompanying procedures (annuloplasty of the mitral valve and/or coronary aortic bypass grafting) were performed in 12 (15.6%) cases. Additional plasty of valvular cusps was carried out in 9 (11.7%) patients, with rethoracotomy required in 5 (6.4%) cases due to haemorrhage. The average period of follow up amounted to 53.3±8.5 (3-115) months. During this time total survival amounted to 91%, with freedom from aortic valve prosthetic repair equalling 93%. The obtained findings suggest that aortic valve reimplantation into the prosthesis is a safe intervention and associated with a comparatively low level of operative lethality. Moderate aortic

  15. Factors involved in the antinatriuretic effects of acute constriction of the thoracic and abdominal inferior vena cava.

    NASA Technical Reports Server (NTRS)

    Schrier, R. W.; Humphreys, M. H.

    1971-01-01

    Study of the antinatriuretic effect of acute thoracic inferior vena cava (TIVC) constriction in the absence of alterations in renal perfusion pressure. A comparison is made of the effects of equivalent degrees of TIVC and abdominal inferior vena cava constriction on arterial pressure, renal hemodynamics, and electrolyte excretion.

  16. Imaging a boa constrictor--the incomplete double aortic arch syndrome.

    PubMed

    Narayan, Rajeev L; Kanwar, Anubhav; Jacobi, Adam; Sanz, Javier

    2012-11-01

    Incomplete double aortic arch is a rare anomaly resulting from atresia rather than complete involution in the distal left arch resulting in a non-patent fibrous cord between the left arch and descending thoracic aorta. This anatomic anomaly may cause symptomatic vascular rings, leading to stridor, wheezing, or dysphagia, requiring surgical transection of the fibrous cord. Herein, we describe an asymptomatic 59 year-old man presenting for contrast-enhanced CT angiography to assess cardiac anatomy prior to radiofrequency ablation, who was incidentally found to have an incomplete double aortic arch with hypoplasia of the left arch segment and an aortic diverticulum. Recognition of this abnormality by imaging is important to inform both corrective surgery in symptomatic patients, as well as assist in the planning of percutaneous coronary and vascular interventions.

  17. Comparative study of calcified changes in aortic valvular diseases.

    PubMed

    Togashi, Mayuko; Tamura, Koichi; Masuda, Yukinari; Fukuda, Yuh

    2008-06-01

    Calcification of the aortic valve leads to stenosis or regurgitation or both. To clarify the mechanism of heart valve calcification, comparative studies using histological and ultrastructural examinations were performed of calcified aortic valves. These valves were obtained at valve replacement surgery from 11 patients with rheumatic aortic valvular disease (RAVD), 10 patients with degenerative aortic valve disease (DAVD), and 10 patients with congenitally bicuspid aortic valves (CBAV). For electron microscopic study, 5 cases were selected from each group. In RAVD, histological examination revealed calcification in a degenerated amorphous area at the center of fibrous thickened regions and in laminar fibrous thickened areas near the valve surface. In DAVD, calcification was observed mainly in the fibrosa near the valve ring. In CBAV, basic pathological changes were similar to those in DAVD; however, additional severe calcification of the raphe was observed, if the raphe was present. Ultrastructural examinations showed deposition of electron-dense materials in two patterns in all three groups; one pattern was observed in the interfibrillar spaces of collagen fibrils, and the other pattern was widespread macular deposition unrelated to the preexisting structure. In RAVD, microfibril-like fibrillar structures were found in the areas of deposition of electron-dense materials. These findings suggest that newly formed connective tissue degraded and became necrotic because of nutritional deprivation, especially in the thickened central area, causing calcium deposition. In DAVD and CBAV, numerous lipid vacuoles were found in the electron-dense deposition areas similar to lipid deposition in aortic atherosclerosis. Localized calcium deposition in the fibrosa suggests that the stress of valvular motion and pressure load induces sclerotic changes with the degeneration of collagen fibers, providing a core for calcification. In CBAV, the raphe was the main location of

  18. A stone miner with both silicosis and constrictive pericarditis: case report and review of the literature

    PubMed Central

    2013-01-01

    Background The working environment of stone miners has been believed to cause their susceptibility to respiratory diseases. Silicosis is an occupational disease caused by exposure to crystalline silica dust which is marked by inflammation and scarring in the lung. The immune system boosted after the silica invasion led to self-damage and lay the foundation of silicosis pathogenesis. Silicosis coexisting with other diseases in one patient has been reported, however, was not reported to coexist with constrictive pericarditis. We, for the first time, reported a patient with silicosis and constrictive pericarditis and thought the immune response was probably the link between the two. Case presentation A 59-year-old Chinese stone miner complained of chest distress was found to have lung nodules which were found to be silica deposits by biopsy. This patient was also found to have constrictive pericarditis at the same time. Later surgical decortication cured his symptoms. Conclusion We provided the first case having constrictive pericarditis concomitant with silicosis. A probable link between the two diseases was the immune response boosted by the silica deposits. PMID:24314106

  19. Effects of renal lymphatic occlusion and venous constriction on renal function.

    PubMed Central

    Stolarczyk, J.; Carone, F. A.

    1975-01-01

    The effects of renal lymphatic occlusion or increased lymph flow due to renal vein constriction on renal function were investigated in rats. In each experiment, the renal lymphatics or vein of the left kidney were occluded or constricted and the right kidney served as a control. Occlusion of renal lymphatics caused renal enlargement, no change in glomerular filtration rate, a marked increase in urine flow and solute excretion without any change in urine osmolality, and enhanced urinary loss of urea, potassium, sodium and ammonium. Urea concentrations in medullary and papillary tissues were significantly elevated. Renal vein constriction caused renal enlargement and a marked drop in glomerular filtration rate, urine volume, urine osmolality and solute excretion. tissue concentrations of urea and potassium were decreased in the medulla and papilla and total tissue solute was significantly decreased in the papilla. The data indicate that in the rat, renal lymphatic occlusion traps urea in the medulla and induces a urea diuresis resulting in a large flow of normally concentrated urine. On the other hand, increased lymph flow secondary to renal vein constriction decreases medullary urea and potassium concentrations and papillary osmolality. These changes and the reduced glomerular filtration rate result in a small flow if dilute urine. Thus both renal lymphatic occlusion and enhanced lymph flow have a significant effect on renal function. Images Fig 1 PMID:1122006

  20. Ameliorative potential of Ocimum sanctum in chronic constriction injury-induced neuropathic pain in rats.

    PubMed

    Kaur, Gurpreet; Bali, Anjana; Singh, Nirmal; Jaggi, Amteshwar S

    2015-03-01

    The present study was designed to investigate the ameliorative potential of Ocimum sanctum and its saponin rich fraction in chronic constriction injury-induced neuropathic pain in rats. The chronic constriction injury was induced by placing four loose ligatures around the sciatic nerve, proximal to its trifurcation. The mechanical hyperalgesia, cold allodynia, paw heat hyperalgesia and cold tail hyperalgesia were assessed by performing the pinprick, acetone, hot plate and cold tail immersion tests, respectively. Biochemically, the tissue thio-barbituric acid reactive species, super-oxide anion content (markers of oxidative stress) and total calcium levels were measured. Chronic constriction injury was associated with the development of mechanical hyperalgesia, cold allodynia, heat and cold hyperalgesia along with an increase in oxidative stress and calcium levels. However, administration of Ocimum sanctum (100 and 200 mg/kg p.o.) and its saponin rich fraction (100 and 200 mg/kg p.o.) for 14 days significantly attenuated chronic constriction injury-induced neuropathic pain as well as decrease the oxidative stress and calcium levels. It may be concluded that saponin rich fraction of Ocimum sanctum has ameliorative potential in attenuating painful neuropathic state, which may be attributed to a decrease in oxidative stress and calcium levels. PMID:25673470

  1. Localization of endothelin ETA and ETB receptor-mediated constriction in the renal microcirculation of rats.

    PubMed Central

    Endlich, K; Hoffend, J; Steinhausen, M

    1996-01-01

    1. The aim of the study was to visualize endothelin-1 (ET-1)-mediated constriction in renal vessels of cortical and juxtamedullary glomeruli in the split hydronephrotic rat kidney in vivo and to functionally characterize the ET receptor subtypes involved. 2. ET-1 (10(-9) M) constricted preglomerular vessels (by 6-18%) and efferent arterioles (by 11-13%), and decreased glomerular blood flow (GBF, by 55%) of cortical and juxtamedullary glomeruli. 3. The ETA antagonist BQ-123 (10(-6) M), as well as the ETB antagonist BQ-788 (2 x 10(-7) M) and IRL 1038 (10(-6) M), shifted the concentration-response curve of GBF for ET-1 to the right by one order of magnitude. While BQ-123 antagonized ET-1 constriction only in preglomerular vessels, BQ-788 and IRL 1038 were effective both in preglomerular vessels and efferent arterioles. 4. The ETB agonist IRL 1620 (10(-8) M) reduced GBF by 50% and constricted efferent arterioles (by 20-33%) about two times more than preglomerular vessels (by 6-14%). 5. Our results suggest that in renal cortical and juxtamedullary vessels of rats, ET-1-induced preglomerular vasoconstriction is mediated by ETA and ETB receptors, while efferent vasoconstriction is predominantly mediated by ETB receptors, which might have important consequences for the regulation of glomerular filtration pressure by ET. PMID:8951723

  2. Visual field constriction as a cause of blindness or visual impairment.

    PubMed Central

    Murdoch, I. E.; Jones, B. R.; Cousens, S.; Liman, I.; Babalola, O. E.; Dauda, J.; Abiose, A.

    1997-01-01

    Reported are the results of a study of onchocerciasis in communities mesoendemic for savanna onchocerciasis in Kaduna State, northern Nigeria. The study involved 6831 individuals aged > or = 5 years who underwent an extensive screening examination for visual function including Friedmann field analysis. A total of 185 (2.7%) were bilaterally blind by acuity and an additional 28 (0.4%) were blind by visual field constriction. Also 118 (1.7%) individuals were visually impaired by acuity criteria. No criteria for visual impairment by field constriction have been established, and we therefore investigated three potential criteria. As a result, a further 60 (0.9%) individuals were identified with significant visual impairment due to field loss by the various definitions. Small islands of remaining peripheral field occurred in 50 individuals, while 40 individuals had marked reduction of binocular visual field below the horizontal meridian. Concentric visual field constriction to < 20 degrees was found in seven individuals. The WHO definition of blindness currently includes visual field damage criteria for blindness but not for visual impairment. Visual field loss is recognized as a major disability. We hope that these findings stimulate international discussion leading to the development of satisfactory definitions for visual impairment by visual field constriction. PMID:9185366

  3. Tenascin-C induces prolonged constriction of cerebral arteries in rats.

    PubMed

    Fujimoto, Masashi; Suzuki, Hidenori; Shiba, Masato; Shimojo, Naoshi; Imanaka-Yoshida, Kyoko; Yoshida, Toshimichi; Kanamaru, Kenji; Matsushima, Satoshi; Taki, Waro

    2013-07-01

    Tenascin-C (TNC), a matricellular protein, is induced in association with cerebral vasospasm after subarachnoid hemorrhage. The aim of this study was to assess the vasoconstrictive effects of TNC and its mechanisms of action on cerebral arteries in vivo. Two dosages (1 and 10μg) of TNC were administered intracisternally to healthy rats, and the effects were evaluated by neurobehavioral tests and India-ink angiography at 24, 48, and 72h after the administration. Western blotting and immunohistochemistry were performed to explore the underlying mechanisms on constricted cerebral arteries after 24h. The effects of toll-like receptor 4 (TLR4) antagonists (LPS-RS), c-Jun N-terminal kinase (JNK), and p38 inhibitors (SP600125 and SB203580) on TNC-induced vasoconstriction were evaluated at 24h. Higher dosages of TNC induced more severe cerebral arterial constriction, which continued for more than 72h. TNC administration also upregulated TLR4, and activated JNK and p38 in the smooth muscle cell layer of the constricted cerebral artery. LPS-RS blocked TNC-induced TLR4 upregulation, JNK and p38 activation, and vasoconstrictive effects. SP600125 and SB203580 abolished TNC-induced TLR4 upregulation and vasoconstrictive effects. TNC may cause prolonged cerebral arterial constriction via TLR4 and activation of JNK and p38, which may upregulate TLR4. These findings suggest that TNC causes cerebral vasospasm and provides a novel therapeutic approach against it.

  4. Coordination of peptidoglycan synthesis and outer membrane constriction during Escherichia coli cell division

    PubMed Central

    Gray, Andrew N; Egan, Alexander JF; van't Veer, Inge L; Verheul, Jolanda; Colavin, Alexandre; Koumoutsi, Alexandra; Biboy, Jacob; Altelaar, A F Maarten; Damen, Mirjam J; Huang, Kerwyn Casey; Simorre, Jean-Pierre; Breukink, Eefjan; den Blaauwen, Tanneke; Typas, Athanasios; Gross, Carol A; Vollmer, Waldemar

    2015-01-01

    To maintain cellular structure and integrity during division, Gram-negative bacteria must carefully coordinate constriction of a tripartite cell envelope of inner membrane, peptidoglycan (PG), and outer membrane (OM). It has remained enigmatic how this is accomplished. Here, we show that envelope machines facilitating septal PG synthesis (PBP1B-LpoB complex) and OM constriction (Tol system) are physically and functionally coordinated via YbgF, renamed CpoB (Coordinator of PG synthesis and OM constriction, associated with PBP1B). CpoB localizes to the septum concurrent with PBP1B-LpoB and Tol at the onset of constriction, interacts with both complexes, and regulates PBP1B activity in response to Tol energy state. This coordination links PG synthesis with OM invagination and imparts a unique mode of bifunctional PG synthase regulation by selectively modulating PBP1B cross-linking activity. Coordination of the PBP1B and Tol machines by CpoB contributes to effective PBP1B function in vivo and maintenance of cell envelope integrity during division. DOI: http://dx.doi.org/10.7554/eLife.07118.001 PMID:25951518

  5. Aortic Wall Injury Related to Endovascular Therapy for Aortic Coarctation.

    PubMed

    Tretter, Justin T; Jones, Thomas K; McElhinney, Doff B

    2015-09-01

    Aortic wall complications can occur in unrepaired aortic coarctation (CoA) and after surgical repair or endovascular treatment. This review summarizes the available literature and current understanding of aortic wall injury (AWI) surrounding the management of CoA, focusing specifically on acute and follow-up AWI after endovascular treatment. There have been 23 reported cases of aortic rupture after endovascular treatment for CoA, including angioplasty alone, bare metal stenting, and primary covered stent therapy. Even if these published cases represent only a minority of ruptures that have actually occurred, the incidence is substantially <1%. The incidence of acute aneurysm formation was 0% to 13% after angioplasty, 0% to 5% after bare metal stent placement, and <1% after covered stent placement. The reported incidence and natural history of both acute and new AWI during follow-up after endovascular therapy for CoA varies considerably, likely secondary to ascertainment and reporting biases and inconsistent definitions. Although important AWI after endovascular treatment of CoA seems to be declining in frequency with increasing experience and improving technology, it remains one of the most important potential adverse outcomes. Long-term surveillance for new AWI and monitoring of existing AWI is mandatory, with institution of appropriate treatment when necessary. A central research focus in this population should be determination of the appropriate treatment for both native and recurrent CoA across various ages with regard to limiting recurrent CoA and preventing associated aortic wall complications, in addition to determining the appropriate treatment of various AWI. Consistent definitions and reporting are necessary to truly understand the incidence of, risk factors for, and measures protective against AWI after angioplasty or stent implantation for CoA.

  6. Spectrum of Aortic Valve Abnormalities Associated with Aortic Dilation Across Age Groups in Turner Syndrome

    PubMed Central

    Olivieri, Laura J.; Baba, Ridhwan Y.; Arai, Andrew E.; Bandettini, W. Patricia; Rosing, Douglas R.; Bakalov, Vladimir; Sachdev, Vandana; Bondy, Carolyn A.

    2014-01-01

    Background Congenital aortic valve fusion is associated with aortic dilation, aneurysm and rupture in girls and women with Turner syndrome (TS). Our objective was to characterize aortic valve structure in subjects with TS, and determine the prevalence of aortic dilation and valve dysfunction associated with different types of aortic valves. Methods and Results The aortic valve and thoracic aorta were characterized by cardiovascular magnetic resonance imaging in 208 subjects with TS in an IRB-approved natural history study. Echocardiography was used to measure peak velocities across the aortic valve, and the degree of aortic regurgitation. Four distinct valve morphologies were identified: tricuspid aortic valve (TAV) 64%(n=133), partially fused aortic valve (PF) 12%(n=25), bicuspid aortic valve (BAV) 23%(n=47), and unicuspid aortic valve (UAV) 1%(n=3). Age and body surface area (BSA) were similar in the 4 valve morphology groups. There was a significant trend, independent of age, towards larger BSA-indexed ascending aortic diameters (AADi) with increasing valve fusion. AADi were (mean +/− SD) 16.9 +/− 3.3 mm/m2, 18.3 +/− 3.3 mm/m2, and 19.8 +/− 3.9 mm/m2 (p<0.0001) for TAV, PF and BAV+UAV respectively. PF, BAV, and UAV were significantly associated with mild aortic regurgitation and elevated peak velocities across the aortic valve. Conclusions Aortic valve abnormalities in TS occur with a spectrum of severity, and are associated with aortic root dilation across age groups. Partial fusion of the aortic valve, traditionally regarded as an acquired valve problem, had an equal age distribution and was associated with an increased AADi. PMID:24084490

  7. [Factors facilitating development of degenerative aortic valvular stenosis].

    PubMed

    Andropova, O V; Polubentseva, E I; Anokhin, V N

    2005-01-01

    The aim of the study was to determine factors of risk and progress of aortal valvular calcinosis (AVC) and aortic ostium stenosis (AOS). The subjects were 85 patients with AVC (42--with aortic valvular stenosis (AVS), and 43--without AOS). The study, which included analysis of the lipid and mineral metabolism, and immunological tests, shows that potential factors of AVC are: age (p < 0. 001), osteoporosis (p < 0.03), mitral ring calcification (p = 0.047), dislipidemia (high serum level of total cholesterol, cholesterol of low density lipoproteins, and apoB, atherogenic shift of apoB/apoA-1 ratio, low level of cholesterol of high density lipoproteins (CHDLP)), disbalance between intecellular matrix synthesis and destruction (high concentration of alkaline phosphatase and its bone fraction, and accelerated deoxypyridinoline excretion), inflammation (high concentration of C-reactive protein (CRP), fibrinogen, and interleukin-6 (IL-6)). The factors of AOS were: age (p < 0.001), smoking (p < 0.001), osteoporosis (p = 0.004), AVC (p < 0.001), mitral ring calcinosis (p = 0.033), dislipidemia (high levels of cholesterol of low density and very low density lipoproteins, low concentrations of CHDLP, and apoA-1), degradation of extracellular matrix, and inflammation (high concentrations of CRP, fibrinogen, IL-6, and IL-8). Thus, atherogenic dislipidemia and mineral dysmetabolism disorder facilitate AVC. The revealed immune status changes imply the role of inflammation in the development and progress of AVS.

  8. Vascular airway compression management in a case of aortic arch and descending thoracic aortic aneurysm

    PubMed Central

    Kumar, Alok; Dutta, Vikas; Negi, Sunder; Puri, G. D.

    2016-01-01

    Airway compression due to distal aortic arch and descending aortic aneurysm repair has been documented. This case of tracheal and left main stem bronchus compression due to aortic aneurysm occurred in a 42-year-old man. The airway compression poses a challenge for the anesthesiologist in airway management during aortic aneurysm repair surgery. The fiber-optic bronchoscope is very helpful in decision-making both preoperatively and postoperatively in such cases. We report a case of airway compression in a 42-year-old patient who underwent elective distal aortic arch and descending aortic aneurysm repair. PMID:27397474

  9. Surgical repair for aortic dissection accompanying a right-sided aortic arch.

    PubMed

    Obitsu, Yukio; Koizumi, Nobusato; Iwahashi, Toru; Saiki, Naozumi; Shigematsu, Hiroshi

    2010-01-01

    Aortic anomaly in which a right-sided aortic arch associated with Kommerell's diverticulum and aberrant left subclavian artery is rare. The present report describes a patient with type-B aortic dissection accompanying aortic anomalies consisting of right-sided aortic arch and the left common carotid and left subclavian artery arising from Kommerell's diverticulum. As dissecting aortic aneurysm diameter increased rapidly, Single-stage surgical repair of extensive thoracic aorta was performed through median sternotomy and right posterolateral fifth intercostal thoracotomy, yielding favorable results. Our surgical procedures are discussed.

  10. Surgical repair for aortic dissection accompanying a right-sided aortic arch

    PubMed Central

    2010-01-01

    Aortic anomaly in which a right-sided aortic arch associated with Kommerell's diverticulum and aberrant left subclavian artery is rare. The present report describes a patient with type-B aortic dissection accompanying aortic anomalies consisting of right-sided aortic arch and the left common carotid and left subclavian artery arising from Kommerell's diverticulum. As dissecting aortic aneurysm diameter increased rapidly, Single-stage surgical repair of extensive thoracic aorta was performed through median sternotomy and right posterolateral fifth intercostal thoracotomy, yielding favorable results. Our surgical procedures are discussed. PMID:20459743

  11. Traumatic aortic regurgitation combined with descending aortic pseudoaneurysm secondary to blunt chest trauma.

    PubMed

    Kim, Siho; Park, Joon Suk; Yoo, Seung Min; Kim, Kyung Ho; Yang, Woo-In; Sung, Jung-Hoon; Kim, In Jai; Lim, Sang-Wook; Cha, Dong-Hun; Moon, Jae-Youn

    2014-09-23

    Rupture of the aorta is a relatively rare complication of blunt chest trauma, and traumatic rupture of the aortic valve is even rarer. Even though both result from blunt chest trauma, the causative mechanisms of aortic valve injury differ from those of descending aortic rupture. There are no previous reports in the literature of simultaneous injuries to both the descending aorta and the aortic valve. We report a case of a 70-year-old man who presented with traumatic aortic regurgitation combined with traumatic pseudoaneurysm of the aortic isthmus following blunt chest trauma, and its successful repair with a hybrid surgical strategy.

  12. Vascular ENaC proteins are required for renal myogenic constriction.

    PubMed

    Jernigan, Nikki L; Drummond, Heather A

    2005-10-01

    The myogenic response is an essential component of renal blood flow autoregulation and is the inherent ability of vascular smooth muscle cells (VSMCs) to contract in response to increases in intraluminal pressure. Although mechanosensitive ion channels are thought to initiate VSMC stretch-induced contraction, their molecular identity is unknown. Recent reports suggest degenerin/epithelial Na(+) channels (DEG/ENaC) may form mechanotransducers in sensory neurons and VSMCs; however, the role of DEG/ENaC proteins in myogenic constriction of mouse renal arteries has not been established. To test the hypothesis that DEG/ENaC proteins are required for myogenic constriction in renal vessels, we first determined expression of ENaC transcripts and proteins in mouse renal VSMCs. Then, we determined pressure- and agonist-induced constriction and changes in vascular smooth muscle cytosolic Ca(2+) and Na(+) in isolated mouse renal interlobar arteries following DEG/ENaC inhibition with amiloride and benzamil. We detect alpha-, beta-, and gammaENaC transcript and protein expression in cultured mouse renal VSMC. In contrast, we detect only beta- and gamma- but not alphaENaC protein in freshly dispersed mrVMSC. Selective DEG/ENaC inhibition, with low doses of amiloride and benzamil, abolishes pressure-induced constriction and increases in cytosolic Ca(2+) and Na(+) without diminishing agonist-induced responses in isolated mouse interlobar arteries. Our findings indicate that DEG/ENaC proteins are required for myogenic constriction in mouse interlobar arteries and are consistent with our hypothesis that DEG/ENaC proteins may be components of mechanosensitive ion channel complexes required for myogenic vasoconstriction. PMID:15914781

  13. Differential effect of spironolactone in chronic constriction injury and vincristine-induced neuropathic pain in rats.

    PubMed

    Jaggi, Amteshwar Singh; Singh, Nirmal

    2010-12-01

    The present study was designed to investigate the ameliorative potential of spironolactone in chronic constriction injury and vincristine-induced neuropathic pain in rats. The chronic constriction injury was induced by placing four loose ligatures around the sciatic nerve, while vincristine (50 μg/kg) was administered for 10 days to induce chemotherapy-induced neuropathic pain. Acetone drop, pin-prick, hot plate and paint brush tests were performed to assess cold allodynia; mechanical and heat hyperalgesia; dynamic mechanical allodynia, respectively. The spontaneous pain and postural index in terms of foot deformity was also assessed. The levels of TNF-α were measured in the sciatic nerve as an index of inflammation. Chronic constriction injury led to significant development of cold allodynia; mechanical and heat hyperalgesia; dynamic mechanical allodynia; spontaneous pain and foot deformity along with rise in the levels of TNF-α. Administration of vincristine was associated with the development of allodynia and hyperalgesia without spontaneous pain, foot deformity and elevation in the levels of TNF-α. Administration of spironolactone (10 and 20 mg/kg) significantly attenuated chronic constriction injury-induced pain related behaviour and foot deformity along with attenuation of TNF-α levels, without modulating vincristine-induced neuropathic pain. The attenuating effect of spironolactone in chronic constriction injury may be due to its anti-inflammatory properties and ability to decrease pro-inflammatory cytokines, while involvement of non-inflammatory mechanisms in the pathogenesis of vincristine-induced pain may probably explain its lack of beneficial effect in chemotherapy associated pain. PMID:20846523

  14. Chronic Type A Aortic Dissection

    PubMed Central

    Hynes, Conor F.; Greenberg, Michael D.; Sarin, Shawn; Trachiotis, Gregory D.

    2016-01-01

    Stanford Type A aortic dissection is a rapidly progressing disease process that is often fatal without emergent surgical repair. A small proportion of Type A dissections go undiagnosed in the acute phase and are found upon delayed presentation of symptoms or incidentally. These chronic lesions may have a distinct natural history that may have a better prognosis and could potentially be managed differently then those presenting acutely. The method of repair depends on location and extent of the false lumen, as well as involvement of critical structures and branch arteries. Surgical repair techniques similar to those employed for acute dissection management are currently first-line therapy for chronic cases that involve the aortic valve, sinuses of Valsalva, coronary arteries, and supra-aortic branch arteries. In patients with high-risk for surgery, endovascular repairs have been successful, and active development of delivery systems and grafts will continue to enhance outcomes. We present two cases of chronic Type A aortic dissection and review the current literature.

  15. Reoperation after vascular ring repair.

    PubMed

    Backer, Carl L; Mongé, Michael C; Russell, Hyde M; Popescu, Andrada R; Rastatter, Jeffrey C; Costello, John M

    2014-01-01

    The majority of patients having surgical intervention for a vascular ring have resolution of their symptoms. However, 5% to 10% of these patients develop recurrent symptoms related either to airway or esophageal compression and may require reoperation. In our series of 300 patients with vascular rings, we performed a reoperation on 26 patients, not all of whom were originally operated on at our institution. The four primary indications for reoperation were Kommerell diverticulum (n = 18), circumflex aorta (n = 2), residual scarring (n = 2), and tracheobronchomalacia requiring aortopexy (n = 4). All patients undergoing reoperation have had preoperative evaluation with bronchoscopy and computed tomographic scanning (CT) with 3-dimensional reconstruction. Patients with dysphagia have had a barium esophagram and esophagoscopy. Patients with a Kommerell diverticulum have undergone resection of the diverticulum and transfer of the left subclavian artery to the left carotid artery. The aortic uncrossing procedure has been used in patients with a circumflex aorta. Aortopexy has been used to treat anterior compression of the trachea by the aorta. Results of these reinterventions have been successful in nearly all cases. Lessons learned from these reoperations can be applied to prevent the need for reoperation by properly selecting the correct initial operation. A dedicated team caring for these children consisting of medical imaging, otolaryngology, cardiovascular-thoracic surgery, and critical care is imperative.

  16. Surgical correction of aortic disease using intraluminal, crimped bovine pericardial graft.

    PubMed

    Bernardes, R de C; Reis Filho, F A; Marino, R L; Marino, M A; de Castro, A C; Rabelo, W; Rabelo, R C

    1995-08-01

    We propose the use of a crimped bovine pericardial graft joined to a rigid and grooved ring for the treatment of aortic dissections and aneurysms. This device was developed to support common tubular vascular prostheses of any material, length, diameter, or form, transforming them into intraluminal ones during the surgical procedure. During March 1989 to May 1994, 74 patients underwent an operation on the aorta in which this intraluminal ring, prepared from a tubular prosthesis of bovine pericardium, was used. Twenty-seven patients had an acute type A aortic dissection, 6 had an acute type B aortic dissection, 10 had annuloaortic ectasia, 6 had a descending aortic aneurysm, 3 had a thoracoabdominal aneurysm, and 22 had an abdominal aneurysm. The global mortality rate of 10.8% in the immediate postoperative period cannot be related to the surgical technique or the type of prosthesis used. We conclude from our findings that this modification of the sutureless intraluminal graft, which allows it to be used to replace diseased segments of the aorta, affords the quickest and simplest means of repair and is attended by the least likelihood of anastomotic complications.

  17. Decreased expression of fibulin-4 in aortic wall of aortic dissection.

    PubMed

    Huawei, P; Qian, C; Chuan, T; Lei, L; Laing, W; Wenlong, X; Wenzhi, L

    2014-02-01

    In this research, we will examine the expression of Fibulin-4 in aortic wall to find out its role in aortic dissection development. The samples of aortic wall were obtained from 10 patients operated for acute ascending aortic dissection and five patients for chronic ascending aortic dissection. Another 15 pieces of samples from patients who had coronary artery bypass were as controls. The aortic samples were stained with aldehyde magenta dyeing to evaluate the arrangement of elastic fibers. The Fibulin-4 protein and mRNA expression were both determined by Western blot and realtime quantitative polymerase chain reaction. Compared with the control group, both in acute and chronic ascending aortic dissection, elastic fiber fragments increased and the expression of fibulin-4 protein significantly decreased (P= 0.045 < 0.05). The level of fibulin-4 mRNA decreased in acute ascending aortic dissection (P= 0.034 < 0.05), while it increased in chronic ascending aortic dissection (P=0.004 < 0.05). The increased amounts of elastic fiber fragments were negatively correlated with the expression of fibulin-4 mRNA in acute ascending aortic dissection. In conclusion, in aortic wall of ascending aortic dissection, the expression of fibulin-4 protein decreased and the expression of fibulin-4 mRNA was abnormal. Fibulin-4 may play an important role in the pathogenesis of aortic dissection.

  18. Decellularized aortic homografts for aortic valve and aorta ascendens replacement†

    PubMed Central

    Tudorache, Igor; Horke, Alexander; Cebotari, Serghei; Sarikouch, Samir; Boethig, Dietmar; Breymann, Thomas; Beerbaum, Philipp; Bertram, Harald; Westhoff-Bleck, Mechthild; Theodoridis, Karolina; Bobylev, Dmitry; Cheptanaru, Eduard; Ciubotaru, Anatol; Haverich, Axel

    2016-01-01

    OBJECTIVES The choice of valve prosthesis for aortic valve replacement (AVR) in young patients is challenging. Decellularized pulmonary homografts (DPHs) have shown excellent results in pulmonary position. Here, we report our early clinical results using decellularized aortic valve homografts (DAHs) for AVR in children and mainly young adults. METHODS This prospective observational study included all 69 patients (44 males) operated from February 2008 to September 2015, with a mean age of 19.7 ± 14.6 years (range 0.2–65.3 years). In 18 patients, a long DAH was used for simultaneous replacement of a dilated ascending aorta as an extended aortic root replacement (EARR). Four patients received simultaneous pulmonary valve replacement with DPH. RESULTS Thirty-nine patients (57%) had a total of 62 previous operations. The mean aortic cross-clamp time in isolated cases was 129 ± 41 min. There was 1 conduit-unrelated death. The mean DAH diameter was 22.4 ± 3.7 mm (range, 10–29 mm), the average peak gradient was 14 ± 15 mmHg and the mean aortic regurgitation grade (0.5 = trace, 1 = mild) was 0.6 ± 0.5. The mean effective orifice area (EOA) of 25 mm diameter DAH was 3.07 ± 0.7 cm2. DAH annulus z-values were 1.1 ± 1.1 at implantation and 0.7 ± 1.3 at the last follow-up. The last mean left ventricle ejection fraction and left ventricle end diastolic volume index was 63 ± 7% and 78 ± 16 ml/m2 body surface area, respectively. To date, no dilatation has been observed at any level of the graft during follow-up; however, the observational time is short (140.4 years in total, mean 2.0 ± 1.8 years, maximum 7.6 years). One small DAH (10 mm at implantation) had to be explanted due to subvalvular stenosis and developing regurgitation after 4.5 years and was replaced with a 17 mm DAH without complication. No calcification of the explanted graft was noticed intraoperatively and after histological analysis, which revealed extensive recellularization without inflammation

  19. MDCT evaluation of acute aortic syndrome (AAS).

    PubMed

    Valente, Tullio; Rossi, Giovanni; Lassandro, Francesco; Rea, Gaetano; Marino, Maurizio; Muto, Maurizio; Molino, Antonio; Scaglione, Mariano

    2016-01-01

    Non-traumatic acute thoracic aortic syndromes (AAS) describe a spectrum of life-threatening aortic pathologies with significant implications on diagnosis, therapy and management. There is a common pathway for the various manifestations of AAS that eventually leads to a breakdown of the aortic intima and media. Improvements in biology and health policy and diffusion of technology into the community resulted in an associated decrease in mortality and morbidity related to aortic therapeutic interventions. Hybrid procedures, branched and fenestrated endografts, and percutaneous aortic valves have emerged as potent and viable alternatives to traditional surgeries. In this context, current state-of-the art multidetector CT (MDCT) is actually the gold standard in the emergency setting because of its intrinsic diagnostic value. Management of acute aortic disease has changed with the increasing realization that endovascular therapies may offer distinct advantages in these situations. This article provides a summary of AAS, focusing especially on the MDCT technique, typical and atypical findings and common pitfalls of AAS, as well as recent concepts regarding the subtypes of AAS, consisting of aortic dissection, intramural haematoma, penetrating atherosclerotic ulcer and unstable aortic aneurysm or contained aortic rupture. MDCT findings will be related to pathophysiology, timing and management options to achieve a definite and timely diagnostic and therapeutic definition. In the present article, we review the aetiology, pathophysiology, clinical presentation, outcomes and therapeutic approaches to acute aortic syndromes. PMID:27033344

  20. Subtle-discrete aortic dissection without bulging of the aortic wall. A rare but lethal lesion.

    PubMed

    Kalogerakos, Paris Dimitrios; Kampitakis, Emmanouil; Pavlopoulos, Dionisios; Chalkiadakis, George; Lazopoulos, George

    2016-08-01

    We report a subtle-discrete aortic dissection, without bulging of the aortic wall or aneurysm or valve pathology or periaortic effusion, which resulted in a lethal cardiac tamponade to a 35-year-old male. PMID:27357491

  1. Spring retractor: a new adjunct for aortic valve surgery.

    PubMed

    Izzat, Mohammad Bashar

    2011-07-01

    We describe a new aortic retractor that is effective in maintaining aortic root geometry and providing for adequate intraoperative visual valve assessment, and therefore enables the surgeon to perform precise aortic valve repair or replacement procedures.

  2. Double incomplete aortic arch and Kommerell's Diverticulum as a cause of chronic cough.

    PubMed

    Sierra-Galan, Lilia M; Shveid-Gerson, Daniela; Gomez-Garza, Gilberto; Rey-Rodriguez, Alejandro

    2015-01-01

    Vascular rings which can cause symptoms related the trachea and esophagus compression occur in less than 1% of all cardiovascular malformations. Double incomplete aortic arch with right-sided aorta and aberrant left subclavian artery is the rarest one, and its present in 0.04-0.1% of autopsy series. A case of this malformation with a Kommerell's Diverticulum is presented. This diverticulum has risk of severe complications such as dissection and/or rupture.

  3. Thoracoscopic correction of a congenital persistent right aortic arch in a young cat

    PubMed Central

    Plesman, Rhea; Johnson, Matthew; Rurak, Sarah; Ambrose, Barbara; Shmon, Cindy

    2011-01-01

    A 9-week-old kitten was diagnosed with a congenital vascular ring anomaly by means of an esophageal contrast study. At 6 mo of age, a non-selective vascular study was used to diagnose a persistent right aortic arch (PRAA). Left-sided thoracoscopic surgery was performed, using a Liga-Sure vessel sealant device to seal and transect the ligamentum arteriosum. PMID:22467970

  4. Type B Aortic Dissection Repair Using a Thoraflex Hybrid Prosthesis in a Complex Aortic Arch Anatomy

    PubMed Central

    Ghanem, Moussa Abi; Gomez-Sanchez, Mario; Chaufour, Xavier; Marcheix, Bertrand

    2016-01-01

    Thoracic endovascular aortic repair (TEVAR) is recognized as an attractive option to treat complicated Type B aortic dissection. Nevertheless, TEVAR is not always technically possible. We report the case of a 53-year-old male with complicated Type B aortic dissection, in the setting of a complex anomalous aortic arch anatomy with an aneurysmal aberrant right subclavian artery. He was successfully treated by the frozen elephant trunk technique using the Thoraflex hybrid graft.

  5. Severe Aortic Stenosis Associated with Unicommissural Unicuspid Aortic Valve in a Middle Aged Male

    PubMed Central

    Kwon, Hee-Jin; Kim, Song Soo; Sun, Byung Joo; Jin, Sun Ah; Kim, Jun-Hyung; Lee, Jae-Hwan; Choi, Siwan; Jeong, Jin-Ok; Seong, In-Whan

    2016-01-01

    Unicuspid aortic valve (UAV) is an extremely rare form of congenital aortic valvular abnormality. Although UAV shows similar clinical characteristics to bicuspid aortic valve, the clinical symptoms develop at earlier age and progress at a faster pace in UAV. In this report, we are presenting a 42-year-old male with severe aortic stenosis associated with unicommissural UAV. The patients underwent a successful Bentall operation. PMID:27721957

  6. Asymmetric dipolar ring

    DOEpatents

    Prosandeev, Sergey A.; Ponomareva, Inna V.; Kornev, Igor A.; Bellaiche, Laurent M.

    2010-11-16

    A device having a dipolar ring surrounding an interior region that is disposed asymmetrically on the ring. The dipolar ring generates a toroidal moment switchable between at least two stable states by a homogeneous field applied to the dipolar ring in the plane of the ring. The ring may be made of ferroelectric or magnetic material. In the former case, the homogeneous field is an electric field and in the latter case, the homogeneous field is a magnetic field.

  7. Transcatheter aortic valve implantation in Jehovah's Witness patients with symptomatic severe aortic valve stenosis

    PubMed Central

    Buz, Semih; Pasic, Miralem; Unbehaun, Axel; Hetzer, Roland

    2012-01-01

    Transcatheter aortic valve implantation (TAVI) is currently reserved for high or prohibitive surgical-risk patients with aortic valve stenosis. We report on successful TAVI in two Jehovah's witness patients. It offers a simple and effective treatment of severe aortic valve stenosis in high-risk patients who refuse the use of allogeneic blood and blood products. PMID:22753437

  8. Contemporary management of aortic stenosis: surgical aortic valve replacement remains the gold standard.

    PubMed

    Walther, Thomas; Blumenstein, Johannes; van Linden, Arnaud; Kempfert, Jörg

    2012-11-01

    Aortic valve disease is the most frequent acquired heart valve lesion in humans. In western communities, approximately 90% of patients present with aortic stenosis (AS), predominantly of a calcific degenerative aetiology. The remaining approximately 10% of patients predominantly present with aortic valve incompetence.

  9. Cervical aortic arch and a new type of double aortic arch. Report of a case.

    PubMed Central

    Cornali, M; Reginato, E; Azzolina, G

    1976-01-01

    A case of cervical aortic arch is reported. To the best of our knowledge, it is the first to be associated with a serious intracardiac anomaly. In addition, it is part of a new type of double aortic arch, caused by failure of reabsorption of both dorsal aortic roots and persistence of the fourth right and second (or third) left branchial arches. PMID:971387

  10. Aortic Valve Surgery: Minimally Invasive Options

    PubMed Central

    Ramlawi, Basel; Bedeir, Kareem; Lamelas, Joseph

    2016-01-01

    Minimally invasive aortic valve surgery has not been adopted by a significant proportion of cardiac surgeons despite proven benefits. This may be related to a high learning curve and technical issues requiring retraining. In this review, we discuss the data for minimally invasive aortic valve surgery and describe our operative technique for both ministernotomy and anterior thoracotomy approaches. We also discuss the advent of novel sutureless valves and how these techniques compare to available transcatheter aortic valve procedures. PMID:27127559

  11. Spontaneous Sealing of a Type Ia Endoleak after Ovation Stent Graft Implantation in a Patient with On-Label Aortic Neck Anatomy.

    PubMed

    Pranteda, Chiara; Sirignano, Pasqualino; Capoccia, Laura; Mansour, Wassim; Montelione, Nunzio; Speziale, Francesco

    2016-07-01

    We report a case of an early type Ia endoleak after endovascular aneurysm repair (EVAR) of an abdominal aortic aneurysm by Ovation Stent Graft implantation and spontaneously resolved without further reintervention. The patient presents a conical aortic neck, but EVAR was performed within the instruction for use proposed by manufactory. At completion angiography, a low-flow type Ia endoleak was present and left untreated. Computed tomographic angiography performed on the third postoperative day showed infolding of the 2 sealing rings. The patient was dismissed without further treatment. At 3-month follow-up, the leak appeared spontaneously sealed with partial expansion of the 2 rings.

  12. Aortic root dilatation in young men with normally functioning bicuspid aortic valves

    PubMed Central

    Nistri, S; Sorbo, M; Marin, M; Palisi, M; Scognamiglio, R; Thiene, G

    1999-01-01

    OBJECTIVE—To evaluate the dimensions of the aortic root in a selected population of young males with isolated normally functioning bicuspid aortic valve.
DESIGN AND SETTING—Echocardiographic and Doppler evaluation of conscripts with bicuspid aortic valve at the time of military pre-enrolment screening in two military hospitals.
SUBJECTS AND METHODS—66 consecutive young men with a normally functioning bicuspid aortic valve were studied to assess aortic size at four aortic levels: annulus, sinuses of Valsalva, supra-aortic ridge, and proximal ascending aorta; 70 consecutive normal young subjects, matched for age and body surface area, were used as controls.
RESULTS—In men with a bicuspid aortic valve, the diameter of the aortic root was significantly larger than in controls at the sinuses (3.16 (0.37) v 2.87 (0.31) cm, p < 0.001), at the supra-aortic ridge (2.64 (0.46) v 2.47 (0.28) cm, p = 0.01), and at the level of the proximal ascending aorta (3.12 (0.48) v 2.69 (0.28) cm, p < 0.001). The prevalence of aortic root dilatation was 7.5% at the annulus (5/66), 19.6% at the sinuses (13/66), 15% at the supra-aortic ridge (10/66), and 43.9% at the ascending aorta (29/66); 32 subjects (48%) had aortic root dimensions comparable with controls, while 34 (52%) had definitely abnormal aortic root dimensions.
CONCLUSIONS—Aortic root enlargement in people with a bicuspid aortic valve occurs independently of haemodynamic abnormalities, age, and body size. However, there appear to be different subgroups of young adults with bicuspid aortic valves, one of which is characterised by aortic dilatation, possibly caused by a congenital abnormality of the aortic wall.


Keywords: bicuspid aortic valve; aortic root dilatation PMID:10377302

  13. [Restrictive cardiomyopathy versus constrictive pericarditis in patients with diastolic dysfunction: MR imaging features].

    PubMed

    Croisille, P

    2010-05-01

    Restrictive cardiomyopathies are characterized by diastolic dysfunction while systolic function is usually preserved. MRI is helpful by its ability to characterize tissues, especially the demonstration of interstitial or nodular fibrosis based on the underlying etiology. In the presence of constrictive pericarditis from pericardial inflammation, fibrosis or calcifications, diastolic expansion is impaired resulting in poor diastolic ventricular filling, resulting in a characteristic type of diastolic impairment, adiastole. MRI can demonstrate the underlying anatomical lesion: pericardial thickening, though the presence of a pericardium or normal thickness does not entirely exclude the possibility of constriction. As such, the presence of additional imaging features such as abnormal right ventricular shape, vena cava dilatation, and paradoxical movement of the intraventricular septum, during operator-guided deep respiration. PMID:20657369

  14. Experimental study of sound production for constricted channels: application to simplified vocal tract geometries

    NASA Astrophysics Data System (ADS)

    Estienne, O.; van Hirtum, A.; Bailliet, H.; Pelorson, X.

    Previous experiments on vocal tract mechanical models for fricatives consonants production -like /s/, /f/,/ch/ for unvoiced ones -has shown the importance of the geometrical configuration on the complex aeroacoustical noise signal produced [3]: the shape of the constriction, the shape and area function of the vocal tract downstream of the constriction, the presence of obstacles like teeth and upstream flow conditions are key points of the frication. From these results, and other observations made on human subjects by Narayanan et al. [2] by means of Magnetic Resonance Imaging (MRI), Howe and McGowan [1] established an aeroacoustical model for the pronunciation of the sibilant /s/ based on the assumption of a jet passing in the gap formed between lower and upper teeth. Predicted spectrum and SPL agreed reasonably well with measurements made previously by different authors, but Howe and McGowan noted that further experimental work is necessary to validate their assumption on turbulent jet interaction with teeth.

  15. An optofluidic constriction chip for monitoring metastatic potential and drug response of cancer cells.

    PubMed

    Martinez Vazquez, R; Nava, G; Veglione, M; Yang, T; Bragheri, F; Minzioni, P; Bianchi, E; Di Tano, M; Chiodi, I; Osellame, R; Mondello, C; Cristiani, I

    2015-04-01

    Cellular mechanical properties constitute good markers to characterize tumor cells, to study cell population heterogeneity and to highlight the effect of drug treatments. In this work, we describe the fabrication and validation of an integrated optofluidic chip capable of analyzing cellular deformability on the basis of the pressure gradient needed to push a cell through a narrow constriction. We demonstrate the ability of the chip to discriminate between tumorigenic and metastatic breast cancer cells (MCF7 and MDA-MB231) and between human melanoma cells with different metastatic potential (A375P and A375MC2). Moreover, we show that this chip allows highlighting the effect of drugs interfering with microtubule organization (paclitaxel, combretastatin A-4 and nocodazole) on cancer cells, which leads to changes in the pressure-gradient required to push cells through the constriction. Our single-cell microfluidic device for mechanical evaluation is compact and easy to use, allowing for an extensive use in different laboratory environments.

  16. The effect of gradually constricted channel on the I-V characteristics of graphene sheets

    NASA Astrophysics Data System (ADS)

    Zanella, Fernando; Nobrega, K. Z.; Dartora, C. A.

    2016-10-01

    Ideal graphene is a gapless semiconductor consisting of a single layer of carbon atoms regularly arranged in a honeycomb lattice having infinite spatial extent in the (x,y)-plane, in which electrons behave as Dirac massless fermions. Even neglecting interactions with the anchoring substrate, a graphene sheet in real world has finite extent, leading to distinctive features in the conductivity of a given sample. In this letter we study the effect of a gradual channel constriction in graphene nanoribbons on their I-V characteristics, using non-equilibrium Green's function formalism. The constriction width and the border cutting angle are the main parameters to be varied. We found that transmission through the channel is considerably affected by these parameters, presenting sharp peaks at specific energies, which can be attributed to a resonance due to the tuning of energy eigenvalues.

  17. Hybrid treatment of penetrating aortic ulcer.

    PubMed

    Lara, Juan Antonio Herrero; Martins-Romêo, Daniela de Araújo; Escudero, Carlos Caparrós; Vázquez, Rosa María Lepe; Falcón, María Del Carmen Prieto; Batista, Vinicius Bianchi

    2015-01-01

    Penetrating atherosclerotic aortic ulcer is a rare entity with poor prognosis in the setting of acute aortic syndrome. In the literature, cases like the present one, located in the aortic arch, starting with chest pain and evolving with dysphonia, are even rarer. The present report emphasizes the role played by computed tomography in the diagnosis of penetrating atherosclerotic ulcer as well as in the differentiation of this condition from other acute aortic syndromes. Additionally, the authors describe a new therapeutic approach represented by a hybrid endovascular surgical procedure for treatment of the disease.

  18. Low-gradient aortic stenosis.

    PubMed

    Clavel, Marie-Annick; Magne, Julien; Pibarot, Philippe

    2016-09-01

    An important proportion of patients with aortic stenosis (AS) have a 'low-gradient' AS, i.e. a small aortic valve area (AVA <1.0 cm(2)) consistent with severe AS but a low mean transvalvular gradient (<40 mmHg) consistent with non-severe AS. The management of this subset of patients is particularly challenging because the AVA-gradient discrepancy raises uncertainty about the actual stenosis severity and thus about the indication for aortic valve replacement (AVR) if the patient has symptoms and/or left ventricular (LV) systolic dysfunction. The most frequent cause of low-gradient (LG) AS is the presence of a low LV outflow state, which may occur with reduced left ventricular ejection fraction (LVEF), i.e. classical low-flow, low-gradient (LF-LG), or preserved LVEF, i.e. paradoxical LF-LG. Furthermore, a substantial proportion of patients with AS may have a normal-flow, low-gradient (NF-LG) AS: i.e. a small AVA-low-gradient combination but with a normal flow. One of the most important clinical challenges in these three categories of patients with LG AS (classical LF-LG, paradoxical LF-LG, and NF-LG) is to differentiate a true-severe AS that generally benefits from AVR vs. a pseudo-severe AS that should be managed conservatively. A low-dose dobutamine stress echocardiography may be used for this purpose in patients with classical LF-LG AS, whereas aortic valve calcium scoring by multi-detector computed tomography is the preferred modality in those with paradoxical LF-LG or NF-LG AS. Although patients with LF-LG severe AS have worse outcomes than those with high-gradient AS following AVR, they nonetheless display an important survival benefit with this intervention. Some studies suggest that transcatheter AVR may be superior to surgical AVR in patients with LF-LG AS.

  19. Endothelial Nitric Oxide Mediates Caffeine Antagonism of Alcohol-Induced Cerebral Artery Constriction.

    PubMed

    Chang, Jennifer; Fedinec, Alexander L; Kuntamallappanavar, Guruprasad; Leffler, Charles W; Bukiya, Anna N; Dopico, Alex M

    2016-01-01

    Despite preventive education, the combined consumption of alcohol and caffeine (particularly from "energy drinks") continues to rise. Physiologic perturbations by separate intake of ethanol and caffeine have been widely documented. However, the biologic actions of the alcohol-caffeine combination and their underlying subcellular mechanisms have been scarcely studied. Using intravital microscopy on a closed-cranial window and isolated, pressurized vessels, we investigated the in vivo and in vitro action of ethanol-caffeine mixtures on cerebral arteries from rats and mice, widely recognized models to address cerebrovascular pathophysiology and pharmacology. Caffeine at concentrations found in human circulation after ingestion of one to two cups of coffee (10 µM) antagonized the endothelium-independent constriction of cerebral arteries evoked by ethanol concentrations found in blood during moderate-heavy alcohol intoxication (40-70 mM). Caffeine antagonism against alcohol was similar whether evaluated in vivo or in vitro, suggesting independence of systemic factors and drug metabolism, but required a functional endothelium. Moreover, caffeine protection against alcohol increased nitric oxide (NO•) levels over those found in the presence of ethanol alone, disappeared upon blocking NO• synthase, and could not be detected in pressurized cerebral arteries from endothelial nitric-oxide synthase knockout (eNOS(-/-)) mice. Finally, incubation of de-endothelialized cerebral arteries with the NO• donor sodium nitroprusside (10 µM) fully restored the protective effect of caffeine. This study demonstrates for the first time that caffeine antagonizes ethanol-induced cerebral artery constriction and identifies endothelial NO• as the critical caffeine effector on smooth muscle targets. Conceivably, situations that perturb endothelial function and/or NO• availability will critically alter caffeine antagonism of alcohol-induced cerebrovascular constriction without

  20. Endothelial Nitric Oxide Mediates Caffeine Antagonism of Alcohol-Induced Cerebral Artery Constriction.

    PubMed

    Chang, Jennifer; Fedinec, Alexander L; Kuntamallappanavar, Guruprasad; Leffler, Charles W; Bukiya, Anna N; Dopico, Alex M

    2016-01-01

    Despite preventive education, the combined consumption of alcohol and caffeine (particularly from "energy drinks") continues to rise. Physiologic perturbations by separate intake of ethanol and caffeine have been widely documented. However, the biologic actions of the alcohol-caffeine combination and their underlying subcellular mechanisms have been scarcely studied. Using intravital microscopy on a closed-cranial window and isolated, pressurized vessels, we investigated the in vivo and in vitro action of ethanol-caffeine mixtures on cerebral arteries from rats and mice, widely recognized models to address cerebrovascular pathophysiology and pharmacology. Caffeine at concentrations found in human circulation after ingestion of one to two cups of coffee (10 µM) antagonized the endothelium-independent constriction of cerebral arteries evoked by ethanol concentrations found in blood during moderate-heavy alcohol intoxication (40-70 mM). Caffeine antagonism against alcohol was similar whether evaluated in vivo or in vitro, suggesting independence of systemic factors and drug metabolism, but required a functional endothelium. Moreover, caffeine protection against alcohol increased nitric oxide (NO•) levels over those found in the presence of ethanol alone, disappeared upon blocking NO• synthase, and could not be detected in pressurized cerebral arteries from endothelial nitric-oxide synthase knockout (eNOS(-/-)) mice. Finally, incubation of de-endothelialized cerebral arteries with the NO• donor sodium nitroprusside (10 µM) fully restored the protective effect of caffeine. This study demonstrates for the first time that caffeine antagonizes ethanol-induced cerebral artery constriction and identifies endothelial NO• as the critical caffeine effector on smooth muscle targets. Conceivably, situations that perturb endothelial function and/or NO• availability will critically alter caffeine antagonism of alcohol-induced cerebrovascular constriction without

  1. Distinct constrictive processes, separated in time and space,divide Caulobacter inner and outer membranes

    SciTech Connect

    Judd, Ellen M.; Comolli, Luis R.; Chen, Joseph C.; Downing,Kenneth H.; Moerner, W.E.; McAdams, Harley H.

    2005-05-01

    Cryo-electron microscope tomography (cryoEM) and a fluorescence loss in photobleaching (FLIP) assay were used to characterize progression of the terminal stages of Caulobacter crescentus cell division. Tomographic cryoEM images of the cell division site show separate constrictive processes closing first the inner, and then the outer, membrane in a manner distinctly different from septum-forming bacteria. The smallest observed pre-fission constrictions were 60 nm for both the inner and outer membrane. FLIP experiments had previously shown cytoplasmic compartmentalization, when cytoplasmic proteins can no longer diffuse between the two nascent progeny cell compartments, occurring 18 min before daughter cell separation in a 135 min cell cycle. Here, we used FLIP experiments with membrane-bound and periplasmic fluorescent proteins to show that (1) periplasmic compartmentalization occurs after cytoplasmic compartmentalization, consistent with the cryoEM observations, and (2) inner membrane and periplasmic proteins can diffuse past the FtsZ constriction site, indicating that the cell division machinery does not block membrane diffusion.

  2. FtsZ does not initiate membrane constriction at the onset of division

    PubMed Central

    Daley, Daniel O.; Skoglund, Ulf; Söderström, Bill

    2016-01-01

    The source of constriction required for division of a bacterial cell remains enigmatic. FtsZ is widely believed to be a key player, because in vitro experiments indicate that it can deform liposomes when membrane tethered. However in vivo evidence for such a role has remained elusive as it has been challenging to distinguish the contribution of FtsZ from that of peptidoglycan-ingrowth. To differentiate between these two possibilities we studied the early stages of division in Escherichia coli, when FtsZ is present at the division site but peptidoglycan synthesizing enzymes such as FtsI and FtsN are not. Our approach was to use correlative cryo-fluorescence and cryo-electron microscopy (cryo-CLEM) to monitor the localization of fluorescently labeled FtsZ, FtsI or FtsN correlated with the septal ultra-structural geometry in the same cell. We noted that the presence of FtsZ at the division septum is not sufficient to deform membranes. This observation suggests that, although FtsZ can provide a constrictive force, the force is not substantial at the onset of division. Conversely, the presence of FtsN always correlated with membrane invagination, indicating that allosteric activation of peptidoglycan ingrowth is the trigger for constriction of the cell envelope during cell division in E. coli. PMID:27609565

  3. Combination of Mandibular Constriction and Intraoral Vertical Ramus Osteotomies for a Transverse Jaw Discrepancy

    PubMed Central

    Mitsugi, Masaharu; Hirose, Hisamitsu; Tatemoto, Yukihiro

    2015-01-01

    Background: The aim of the present study was to evaluate the treatment of patients developing a transverse jaw width discrepancy who exhibited class III malocclusion and/or facial asymmetry by a combination of mandibular constriction (MC) and intraoral vertical ramus osteotomies (IVROs). Subjects and methods: In a retrospective study, functional results, postoperative complications, and skeletal stability were analyzed for all the patients who had undergone MC and IVRO, with more than 2 years of follow-up. A mandibular midline osteotomy for constriction with lag screw technique and IVROs was used for MC and setback. Results: Sixteen patients were included in the present study. The average degree of MC was 6.34 mm. Both the occlusal relationship and facial appearance in all patients were significantly improved by the surgical orthodontic treatment, with no harmful clinical symptoms. In addition, our original MC using lag screw technique provided the most reliable results in terms of skeletal stability. Conclusions: This study showed that MC using lag screw technique gives a very stable mandibular width constriction, and the combination of MC and IVROs offers a promising treatment alternative for patients with mandibular prognathism developing a transverse jaw width discrepancy. PMID:26495234

  4. Constriction structures related to viscous collision, southern Prince Charles Mountains, Antarctica

    NASA Astrophysics Data System (ADS)

    Corvino, Adrian F.; Boger, Steven D.; Fay, Clement

    2016-09-01

    Macroscopic structures are investigated in a zone of highly contorted migmatites from the southern Prince Charles Mountains, Antarctica. Here, L-tectonite fabrics, rods, mullions, boudin pods, elongate enclaves, and fold hinges, are persistent linear features all plunging gently to the northeast. In contrast, amoeboid folds, ptygmatic folds and folded boudins with different orientations are the characteristic structures in transverse sections (perpendicular to the lineation). No consistent shear sense is recognised in any dimension. Together with strain and shape analysis, these observations strongly suggest that the deformation pattern is one of folding and stretching by constriction. Previous timing constraints indicate that this deformation overlapped with the waning stages of anatexis during decompression at approximately 510 Ma, up to 30 million years after initial orogeny at 540 Ma. The zone affected by constriction is several kilometres wide and has a contorted flower-like shape confined between two broad domal antiforms. In this context, the constricted zone is interpreted as a relatively late tectonic feature that could have formed via deep-seated viscous collision in response to orogenic collapse and doming.

  5. FtsZ does not initiate membrane constriction at the onset of division.

    PubMed

    Daley, Daniel O; Skoglund, Ulf; Söderström, Bill

    2016-01-01

    The source of constriction required for division of a bacterial cell remains enigmatic. FtsZ is widely believed to be a key player, because in vitro experiments indicate that it can deform liposomes when membrane tethered. However in vivo evidence for such a role has remained elusive as it has been challenging to distinguish the contribution of FtsZ from that of peptidoglycan-ingrowth. To differentiate between these two possibilities we studied the early stages of division in Escherichia coli, when FtsZ is present at the division site but peptidoglycan synthesizing enzymes such as FtsI and FtsN are not. Our approach was to use correlative cryo-fluorescence and cryo-electron microscopy (cryo-CLEM) to monitor the localization of fluorescently labeled FtsZ, FtsI or FtsN correlated with the septal ultra-structural geometry in the same cell. We noted that the presence of FtsZ at the division septum is not sufficient to deform membranes. This observation suggests that, although FtsZ can provide a constrictive force, the force is not substantial at the onset of division. Conversely, the presence of FtsN always correlated with membrane invagination, indicating that allosteric activation of peptidoglycan ingrowth is the trigger for constriction of the cell envelope during cell division in E. coli. PMID:27609565

  6. FtsZ does not initiate membrane constriction at the onset of division.

    PubMed

    Daley, Daniel O; Skoglund, Ulf; Söderström, Bill

    2016-09-09

    The source of constriction required for division of a bacterial cell remains enigmatic. FtsZ is widely believed to be a key player, because in vitro experiments indicate that it can deform liposomes when membrane tethered. However in vivo evidence for such a role has remained elusive as it has been challenging to distinguish the contribution of FtsZ from that of peptidoglycan-ingrowth. To differentiate between these two possibilities we studied the early stages of division in Escherichia coli, when FtsZ is present at the division site but peptidoglycan synthesizing enzymes such as FtsI and FtsN are not. Our approach was to use correlative cryo-fluorescence and cryo-electron microscopy (cryo-CLEM) to monitor the localization of fluorescently labeled FtsZ, FtsI or FtsN correlated with the septal ultra-structural geometry in the same cell. We noted that the presence of FtsZ at the division septum is not sufficient to deform membranes. This observation suggests that, although FtsZ can provide a constrictive force, the force is not substantial at the onset of division. Conversely, the presence of FtsN always correlated with membrane invagination, indicating that allosteric activation of peptidoglycan ingrowth is the trigger for constriction of the cell envelope during cell division in E. coli.

  7. Biventricular Failure due to Stress Cardiomyopathy after Pericardiectomy for Constrictive Pericarditis

    PubMed Central

    Groves, Elliott M.

    2013-01-01

    Importance. Constrictive pericarditis is a rare clinical entity that frequently necessitates surgical intervention. Here we present a case of biventricular failure due to stress cardiomyopathy after pericardiectomy. This is an extremely rare complication that is not well described and does not have a definitive mechanism. Observations. A 40-year-old Ecuadorian woman who was found to have constrictive pericarditis due to Mycobacterium tuberculosis infection was referred to our institution. The presence of constrictive pericarditis was confirmed by echocardiography, computed tomography, magnetic resonance imaging, and cardiac catheterization. Following pericardiectomy, the patient developed biventricular failure consistent with stress cardiomyopathy (Takotsubo cardiomyopathy), based on the echocardiographic assessment of the ventricles, which demonstrated an akinetic apex and hyperactive base in both ventricles, the absence of significant epicardial coronary atherosclerosis, and prompt normalization of the cardiac function after intensive medical therapy. Conclusions and Relevance. Biventricular failure in the form of stress cardiomyopathy after pericardiectomy in the manner presented here has not been previously described in the literature. While postulations as to the cause of single ventricle dysfunction have been described, the exact mechanism is unclear and current theories do not explain the clinical features in this case of stress cardiomyopathy after pericardiectomy. PMID:24369470

  8. Concomitant axial cineangiography and barium esophagography in the evaluation of vascular rings.

    PubMed

    Tonkin, I L; Elliott, L P; Bargeron, L M

    1980-04-01

    Six vascular rings were evaluated using axial biplane cineangiography and concomitant barium esophagography. Three patients had a double aortic arch, two had a right aortic arch and aberrant left subclavian artery with a foreshortened left ligamentum arteriosum, and one had a pulmonary vascular sling. Barium was administered in the esophagus of the anesthetized patient followed by cineangiography. Five patients were evaluated using both the standard and four-chamber projection, while the sixth patient with the pulmonary sling was evaluated in the standard and sitting projection. With the four-chamber view, vascular rings were exposed and atypical features such as a small right aortic arch component and branch stenoses of the brachiocephalic arteries were revealed. Axial views with an esophagogram allow easier morphologic analysis and more precise definition of the vascular abnormality than conventional views. PMID:7360983

  9. Prenatal Diagnosis of a Fetus with Congenital Heart Defect and Ring Chromosome 14

    PubMed Central

    Sánchez, Javier; García-Díaz, Lutgardo; Chinchón, David; Antiñolo, Guillermo

    2012-01-01

    Monosomy of chromosome 14 has been reported in only a few prenatal cases. Generally, this monosomy is associated with a mosaicism of ring chromosome 14. Ring chromosome 14 is a rare cytogenetic entity with clinical characteristics that include growth retardation, facial dysmorphia, hypotonia, seizures, and retinitis pigmentosa. Given that the majority of symptoms appear postnatally, few cases have been reported of prenatal diagnosis of mosaicism monosomy/ring chromosome 14. We describe the prenatal diagnosis of a case of chromosomal mosaicism, a cell line with ring chromosome 14, r(14), and a second cell line with monosomy 14, in a fetus with aortic coarctation and chamber asymmetry. This is the first case of a prenatal diagnosis associating mosaicism with ring chromosome 14, monosomy 14, and fetal cardiopathy. We identified the exact breakpoint in ring chromosome 14 in IGH locus, which may provide further insight into the mode of ring formation as well as prenatal findings. PMID:23198189

  10. Aortic root disease in athletes: aortic root dilation, anomalous coronary artery, bicuspid aortic valve, and Marfan's syndrome.

    PubMed

    Yim, Eugene Sun

    2013-08-01

    Two professional athletes in the U.S. National Basketball Association required surgery for aortic root dilation in 2012. These cases have attracted attention in sports medicine to the importance of aortic root disease in athletes. In addition to aortic root dilation, other forms of aortic disease include anomalous coronary artery, bicuspid aortic valve, and Marfan's syndrome. In this review, electronic database literature searches were performed using the terms "aortic root" and "athletes." The literature search produced 122 manuscripts. Of these, 22 were on aortic root dilation, 21 on anomalous coronary arteries, 12 on bicuspid aortic valves, and 8 on Marfan's syndrome. Aortic root dilation is a condition involving pathologic dilation of the aortic root, which can lead to life-threatening sequelae. Prevalence of the condition among athletes and higher risk athletes in particular sports needs to be better delineated. Normative parameters for aortic root diameter in the general population are proportionate to anthropomorphic variables, but this has not been validated for athletes at the extremes of anthropomorphic indices. Although echocardiography is the favored screening modality, computed tomography (CT) and cardiac magnetic resonance imaging (MRI) are also used for diagnosis and surgical planning. Medical management has utilized beta-blockers, with more recent use of angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers (ARBs), and statins. Indications for surgery are based on comorbidities, degree of dilation, and rate of progression. Management decisions for aortic root dilation in athletes are nuanced and will benefit from the development of evidence-based guidelines. Anomalous coronary artery is another form of aortic disease with relevance in athletes. Diagnosis has traditionally been through cardiac catheterization, but more recently has included evaluation with echocardiography, multislice CT, and MRI. Athletes with this

  11. WUnicuspid Aortic Valve- An Uncommon Anomaly With a Common Presentation.

    PubMed

    Sitwala, Puja; Abusara, Ashraf; Ladia, Vatsal; Ladia, Vatsal; Panchal, Hemang B; Raudat, Charles; Paul, Timir K

    2016-01-01

    Unicuspid aortic valve (UAV), which is a rare congenital anomaly, usually presents as aortic stenosis and/or aortic regurgitation. Here we present a case of UAV co-existent with an ascending aortic aneurysm. A 26-year-old male with no significant past medical history presented to the hospital after two episodes of syncope. Transthoracic echocardiogram showed an ejection fraction of 62%, severely stenotic aortic valve, and moderate aortic regurgitation. Computed tomography revealed calcification of the aortic valve, compatible with aortic stenosis and aneurysm of the ascending aorta measuring 4.3 cm in diameter. He underwent successful aortic valve replacement and repair of ascending aortic aneurysm. He recovered well without any complications. This case suggests that any young patient who presents with syncope, aortic stenosis would be a differential and further workup by any available non-invasive modality needs to be performed.

  12. The role of transesophageal echocardiography in aortic surgery.

    PubMed

    Nowak-Machen, Martina

    2016-09-01

    Aortic disease, when left untreated, is still associated with major morbidity and mortality. Aortic dissection and aortic aneurysm are the main reasons for performing aortic surgery procedures in the adult. Imaging techniques such as computed tomography and magnetic resonance imaging play a key role in the preoperative evaluation. Transesophageal echocardiography (TEE) has become a safe and invaluable perioperative imaging tool for aortic disease over the past decade with high sensitivity and specificity. TEE can increase patient safety and improve overall patient outcome in aortic surgery. Especially during endovascular aortic repair, TEE is more sensitive than other imaging modalities in diagnosing complications such as graft endoleaks. Newer echocardiographic techniques such as three-dimensional (3D) TEE and contrast-enhanced TEE are emerging and seem to have a valuable role especially in aortic dissection repair and endovascular aortic stent procedures. In the absence of contraindications, TEE should generally be performed during aortic surgery and endovascular aortic procedures. PMID:27650342

  13. [Surgical aspects of acute aortic dissection].

    PubMed

    Laas, J; Heinemann, M; Jurmann, M; Borst, H G

    1992-12-01

    This paper highlights some of the surgical aspects of acute aortic dissections such as: emergency diagnosis, indications for surgery, reconstructive operative techniques, malperfusion phenomena and necessity for follow-up. Aortic dissection is caused by an intimal tear, called the "entry", and subsequent splitting of the media by the stream of blood. Two lumina are thus created, which may communicate through "re-entries". As this creates severe weakness of the aortic wall, rupture and/or dilatation are the imminent dangers of acute aortic dissection. Acute aortic dissection type A, by definition involving the ascending aorta (Figures 1 and 2), is an absolute indication for emergency surgical treatment, because its natural history shows an extremely poor outcome (Figure 3). Due to impending (intrapericardial) aortic rupture, it may be necessary to limit diagnostic procedures to a minimum. Transesophageal echocardiography is the method of choice for establishing a quick, precise and reliable diagnosis (Figure 4). In stable patients, computed tomography gives additional information about aortic diameters or sites of extrapericardial perforation. Digital subtraction angiography (DSA) shows perfusion of the lumina and dependent organs. The surgical strategy in acute aortic dissection type A aims at replacement of the ascending aorta. Reconstructive techniques have to be considered, especially in aortic valve regurgitation without annuloectasia (Figures 5 and 6). In recent times, the use of GRF tissue glue has reduced the need for teflon felt. Involvement of the aortic arch should be treated aggressively up to the point of total arch replacement in deep hypothermic circulatory arrest as part of the primary procedure (Figure 7). Malperfusion phenomena of aortic branches remain risk-factors.(ABSTRACT TRUNCATED AT 250 WORDS)

  14. Aortic Stiffness, Cerebrovascular Dysfunction, and Memory

    PubMed Central

    Cooper, Leroy L.; Mitchell, Gary F.

    2016-01-01

    Background Aortic stiffness is associated with cardiovascular and cerebrovascular events and cognitive decline. This mini-review focuses on relations of aortic stiffness with microvascular dysfunction and discusses the contribution of abnormal pulsatile hemodynamics to cerebrovascular damage and cognitive decline. We also provide a rationale for considering aortic stiffness as a putative and important contributor to memory impairment in older individuals. Summary Aging is associated with stiffening of the aorta but not the muscular arteries, which reduces wave reflection and increases the transmission of pulsatility into the periphery. Aortic stiffening thereby impairs a protective mechanism that shields the peripheral microcirculation from excessive pulsatility within downstream target organs. Beyond midlife, aortic stiffness increases rapidly and exposes the cerebral microcirculation to abnormal pulsatile mechanical forces that are associated with microvascular damage and remodeling in the brain. Aortic stiffening and high-flow pulsatility are associated with alterations in the microvasculature of the brain; however, a mechanistic link between aortic stiffness and memory has not been established. We showed that in a community-based sample of older individuals, cerebrovascular resistance and white matter hyperintensities - markers of cerebrovascular remodeling and damage - mediated the relation between higher aortic stiffness and lower performance on memory function tests. These data suggest that microvascular and white matter damage associated with excessive aortic stiffness contribute to impaired memory function with advancing age. Key Messages Increasing evidence suggests that vascular etiologies - including aortic stiffness and microvascular damage - contribute to memory impairment and the pathogenesis of dementia, including Alzheimer's disease. Interventions that reduce aortic stiffness may delay memory decline among older individuals. PMID:27752478

  15. Stirling engine piston ring

    DOEpatents

    Howarth, Roy B.

    1983-01-01

    A piston ring design for a Stirling engine wherein the contact pressure between the piston and the cylinder is maintained at a uniform level, independent of engine conditions through a balancing of the pressure exerted upon the ring's surface and thereby allowing the contact pressure on the ring to be predetermined through the use of a preloaded expander ring.

  16. Congenital quadricuspid aortic valve associated with aortic insufficiency and mitral regurgitation

    PubMed Central

    2013-01-01

    Congenital quadricuspid aortic valve is a rare cardiac anomaly. More than half of the patients with this abnormality will develop aortic insufficiency in adulthood. It is vital that patients with quadricuspid aortic valve who present with progressive aortic regurgitation undergo valve replacement or repair at appropriate time. Here, we present two cases of quadricuspid aortic valve. We first describe a 58-year-old man who had mitral regurgitation and ascending aorta dilatation with quadricuspid aortic valve. He underwent aortic valve replacement and mitral valve plasty and recovered well. The second patient is a 20-year-old asymptomatic boy who has been closely followed up and has not received any surgical treatment. PMID:23587156

  17. Congenital quadricuspid aortic valve associated with aortic insufficiency and mitral regurgitation.

    PubMed

    Zhu, Jiaquan; Zhang, Junwen; Wu, Shubin; Zhang, Yunjiao; Ding, Fangbao; Mei, Ju

    2013-01-01

    Congenital quadricuspid aortic valve is a rare cardiac anomaly. More than half of the patients with this abnormality will develop aortic insufficiency in adulthood. It is vital that patients with quadricuspid aortic valve who present with progressive aortic regurgitation undergo valve replacement or repair at appropriate time. Here, we present two cases of quadricuspid aortic valve. We first describe a 58-year-old man who had mitral regurgitation and ascending aorta dilatation with quadricuspid aortic valve. He underwent aortic valve replacement and mitral valve plasty and recovered well. The second patient is a 20-year-old asymptomatic boy who has been closely followed up and has not received any surgical treatment. PMID:23587156

  18. ZapE Is a Novel Cell Division Protein Interacting with FtsZ and Modulating the Z-Ring Dynamics

    PubMed Central

    Marteyn, Benoit S.; Karimova, Gouzel; Fenton, Andrew K.; Gazi, Anastasia D.; West, Nicholas; Touqui, Lhousseine; Prevost, Marie-Christine; Betton, Jean-Michel; Poyraz, Oemer; Ladant, Daniel; Gerdes, Kenn; Sansonetti, Philippe J.; Tang, Christoph M.

    2014-01-01

    ABSTRACT Bacterial cell division requires the formation of a mature divisome complex positioned at the midcell. The localization of the divisome complex is determined by the correct positioning, assembly, and constriction of the FtsZ ring (Z-ring). Z-ring constriction control remains poorly understood and (to some extent) controversial, probably due to the fact that this phenomenon is transient and controlled by numerous factors. Here, we characterize ZapE, a novel ATPase found in Gram-negative bacteria, which is required for growth under conditions of low oxygen, while loss of zapE results in temperature-dependent elongation of cell shape. We found that ZapE is recruited to the Z-ring during late stages of the cell division process and correlates with constriction of the Z-ring. Overexpression or inactivation of zapE leads to elongation of Escherichia coli and affects the dynamics of the Z-ring during division. In vitro, ZapE destabilizes FtsZ polymers in an ATP-dependent manner. PMID:24595368

  19. The rings of Saturn

    NASA Technical Reports Server (NTRS)

    Pollack, J. B.

    1978-01-01

    Consideration is given to the development of theories concerning the rings of Saturn. Particular attention is given to ring structure, noting its thinness, the separations between rings, and observed variations in brightness. Data gathered via infrared, radio and radar techniques are described in terms of ring particle composition and size. Hypotheses about ring origin and evolution are outlined, including the tidal disruption model, calculations of Saturn's gravitational contraction history, grazing, and meteoroid bombardment. Prospects for future observations of Saturn's rings are reviewed, such as the variation in their radar reflectivity as a function of the tilt of the ring plane.

  20. New Dust Belts of Uranus: One Ring, Two Ring, Red Ring, Blue Ring

    SciTech Connect

    de Pater, I; Hammel, H B; Gibbard, S G; Showalter, M R

    2006-02-02

    We compare near-infrared observations of the recently discovered outer rings of Uranus with HST results. We find that the inner ring, R/2003 U 2, is red, whereas the outer ring, R/2003 U 1, is very blue. Blue is an unusual color for rings; Saturn's enigmatic E ring is the only other known example. By analogy to the E ring, R/2003 U 1 is probably produced via impacts into the embedded moon Mab, which apparently orbits at a location where non-gravitational perturbations favor the survival and spreading of sub-micron sized dust. R/2003 U 2 more closely resembles Saturn's G ring.

  1. High-resolution ultrasonographic evaluation of "hourglass-like fascicular constriction" in peripheral nerves: a preliminary report.

    PubMed

    Nakashima, Yuko; Sunagawa, Toru; Shinomiya, Rikuo; Ochi, Mitsu

    2014-07-01

    An hourglass-like constriction is a focal fascicular lesion observed in one or a few places in one or a few fascicles of a peripheral nerve trunk, and usually affects the anterior interosseous (AIN) or posterior interosseous (PIN) nerve. Constrictions have previously been discovered only by surgical exploration, and have been unable to be recognized on pre-operative imaging. We encountered some cases in which the lesion was able to be diagnosed pre-operatively by high-resolution ultrasonography; these findings were then confirmed intra-operatively. Five consecutive cases were included in this study. In three cases with constrictions revealed on pre-operative ultrasound, the findings were confirmed intra-operatively. In the remaining two cases in which no constrictions were detected pre-operatively, no constriction was revealed intra-operatively. High-resolution ultrasonography may play a significant role in the diagnosis of hourglass-like constrictions, and may thus lead to significant changes in treatment strategies for AIN and PIN palsy.

  2. Recent advances in aortic valve replacement for aortic stenosis

    PubMed Central

    Al-Adhami, Ahmed; Al-Attar, Nawwar

    2016-01-01

    Aortic valve replacement is no longer an operation that is approached solely through a median sternotomy. Recent advances in the fields of transcatheter valves have expanded the proportion of patients eligible for intervention. Comparisons between transcatheter valves and conventional surgery have shown non-inferiority of transcatheter valve implants in patients with a high or intermediate pre-operative predictive risk. With advances in our understanding of sutureless valves and their applicability to minimally invasive surgery, the invasiveness and trauma of surgery can be reduced with potential improvements in outcome. The strategy of care has radically changed over the last decade. PMID:27803800

  3. Intraoperative tracking of aortic valve plane

    PubMed Central

    Nguyen, Duc Long Hung; Garreau, Mireille; Auffret, Vincent; Le Breton, Hervé; Verhoye, Jean-Philippe; Haigron, Pascal

    2013-01-01

    The main objective of this work is to track the aortic valve plane in intra-operative fluoroscopic images in order to optimize and secure Transcatheter Aortic Valve Implantation (TAVI) procedure. This paper is focused on the issue of aortic valve calcifications tracking in fluoroscopic images. We propose a new method based on the Tracking-Learning-Detection approach, applied to the aortic valve calcifications in order to determine the position of the aortic valve plane in intra-operative TAVI images. This main contribution concerns the improvement of object detection by updating the recursive tracker in which all features are tracked jointly. The approach has been evaluated on four patient databases, providing an absolute mean displacement error less than 10 pixels ≈ 2mm). Its suitability for the TAVI procedure has been analyzed. PMID:24110703

  4. Organ protection during aortic cross-clamping.

    PubMed

    Yeung, Kak Khee; Groeneveld, Menno; Lu, Joyce Ja-Ning; van Diemen, Pepijn; Jongkind, Vincent; Wisselink, Willem

    2016-09-01

    Open surgical repair of an aortic aneurysm requires aortic cross-clamping, resulting in temporary ischemia of all organs and tissues supplied by the aorta distal to the clamp. Major complications of open aneurysm repair due to aortic cross-clamping include renal ischemia-reperfusion injury and postoperative colonic ischemia in case of supra- and infrarenal aortic aneurysm repair. Ischemia-reperfusion injury results in excessive production of reactive oxygen species and in oxidative stress, which can lead to multiple organ failure. Several perioperative protective strategies have been suggested to preserve renal function during aortic cross-clamping, such as pharmacotherapy and therapeutic hypothermia of the kidneys. In this chapter, we will briefly discuss the pathophysiology of ischemia-reperfusion injury and the preventative measures that can be taken to avoid abdominal organ injury. Finally, techniques to minimize the risk of complications during and after open aneurysm repair will be presented. PMID:27650341

  5. Plasma Levels of Transforming Growth Factor-β1 Reflect Left Ventricular Remodeling in Aortic Stenosis

    PubMed Central

    Villar, Ana V.; Cobo, Manuel; Llano, Miguel; Montalvo, Cecilia; González-Vílchez, Francisco; Martín-Durán, Rafael; Hurlé, María A.; Nistal, J. Francisco

    2009-01-01

    Background TGF-β1 is involved in cardiac remodeling through an auto/paracrine mechanism. The contribution of TGF-β1 from plasmatic source to pressure overload myocardial remodeling has not been analyzed. We investigated, in patients with valvular aortic stenosis (AS), and in mice subjected to transverse aortic arch constriction (TAC), whether plasma TGF-β1 relates with myocardial remodeling, reflected by LV transcriptional adaptations of genes linked to myocardial hypertrophy and fibrosis, and by heart morphology and function. Methodology/Principal Findings The subjects of the study were: 39 patients operated of AS; 27 healthy volunteers; 12 mice subjected to TAC; and 6 mice sham-operated. Myocardial samples were subjected to quantitative PCR. Plasma TGF-β1 was determined by ELISA. Under pressure overload, TGF-β1 plasma levels were significantly increased both in AS patients and TAC mice. In AS patients, plasma TGF-β1 correlated directly with aortic transvalvular gradients and LV mass surrogate variables, both preoperatively and 1 year after surgery. Plasma TGF-β1 correlated positively with the myocardial expression of genes encoding extracellular matrix (collagens I and III, fibronectin) and sarcomeric (myosin light chain-2, β-myosin heavy chain) remodelling targets of TGF-β1, in TAC mice and in AS patients. Conclusions/Significance A circulating TGF-β1-mediated mechanism is involved, in both mice and humans, in the excessive deposition of ECM elements and hypertrophic growth of cardiomyocytes under pressure overload. The possible value of plasma TGF-β1 as a marker reflecting preoperative myocardial remodeling status in AS patients deserves further analysis in larger patient cohorts. PMID:20041033

  6. Pericarditis - constrictive

    MedlinePlus

    ... slowly and gets worse Fatigue Long-term swelling ( edema ) of the legs and ankles Swollen abdomen Weakness ... Damage to the coronary arteries Heart failure Pulmonary edema Scarring of the heart muscle When to Contact ...

  7. Successful management of para-aortic lymphocyst with laparoscopic fenestration.

    PubMed

    Sarli, L; Cortellini, P; Pavlidis, C; Simonazzi, M; Sebastio, N

    2000-04-01

    Para-aortic lymphocyst occasionally follows retroperitoneal para-aortic node dissection for neoplastic diseases. We present a case in which the leakage of chylous fluid and then a para-aortic lymphocyst followed right nephrectomy and para-aortic node dissection for kidney cancer. Our method of treatment utilized conservative management of chylous ascites and laparoscopic internal drainage of the retroperitoneal lymphocyst.

  8. Endovascular abdominal aortic aneurysm repair

    PubMed Central

    Norwood, M G A; Lloyd, G M; Bown, M J; Fishwick, G; London, N J; Sayers, R D

    2007-01-01

    The operative mortality following conventional abdominal aortic aneurysm (AAA) repair has not fallen significantly over the past two decades. Since its inception in 1991, endovascular aneurysm repair (EVAR) has provided an alternative to open AAA repair and perhaps an opportunity to improve operative mortality. Two recent large randomised trials have demonstrated the short and medium term benefit of EVAR over open AAA repair, although data on the long term efficacy of the technique are still lacking. This review aimed at providing an overview of EVAR and a discussion of the potential benefits and current limitations of the technique. PMID:17267674

  9. Leaking mycotic abdominal aortic aneurysm.

    PubMed

    Sing, T M; Young, N; O'Rourke, I C; Tomlinson, P

    1994-11-01

    A case of leaking mycotic abdominal aortic aneurysm is reported, with a brief review of the literature. A 58 year old female presented with shoulder and abdominal pain associated with diarrhoea, vomiting and fever with leucocytosis. Computed tomography of the abdomen showed pooling of contrast in the retroperitoneum anterior to a non-dilated abdominal aorta. There was considerable retroperitoneal blood accumulating in a mass-like lesion in the right lower abdomen and pelvis obstructing the right renal collecting system. Laparotomy revealed a 4 cm diameter saccular aneurysm of the abdominal aorta, with a 1 cm diameter neck. Culture of the thrombus grew Streptococcus pyogenes. PMID:7993259

  10. Aortic valve and ascending aortic root modeling from 3D and 3D+t CT

    NASA Astrophysics Data System (ADS)

    Grbic, Saša; Ionasec, Razvan I.; Zäuner, Dominik; Zheng, Yefeng; Georgescu, Bogdan; Comaniciu, Dorin

    2010-02-01

    Aortic valve disorders are the most frequent form of valvular heart disorders (VHD) affecting nearly 3% of the global population. A large fraction among them are aortic root diseases, such as aortic root aneurysm, often requiring surgical procedures (valve-sparing) as a treatment. Visual non-invasive assessment techniques could assist during pre-selection of adequate patients, planning procedures and afterward evaluation of the same. However state of the art approaches try to model a rather short part of the aortic root, insufficient to assist the physician during intervention planning. In this paper we propose a novel approach for morphological and functional quantification of both the aortic valve and the ascending aortic root. A novel physiological shape model is introduced, consisting of the aortic valve root, leaflets and the ascending aortic root. The model parameters are hierarchically estimated using robust and fast learning-based methods. Experiments performed on 63 CT sequences (630 Volumes) and 20 single phase CT volumes demonstrated an accuracy of 1.45mm and an performance of 30 seconds (3D+t) for this approach. To the best of our knowledge this is the first time a complete model of the aortic valve (including leaflets) and the ascending aortic root, estimated from CT, has been proposed.

  11. From Unicuspid to Quadricuspid: Influence of Aortic Valve Morphology on Aortic 3D Hemodynamics

    PubMed Central

    Entezari, Pegah; Schnell, Susanne; Mahadevia, Riti; Malaisrie, Chris; McCarthy, Patrick; Mendelson, Marla; Collins, Jeremy; Carr, James C.; Markl, Michael; Barker, Alex J.

    2016-01-01

    Purpose To assess the impact of aortic valve morphology on aortic hemodynamicsbetweennormal tricuspid and congenitally anomalous aortic valvesranging from unicuspid to quadricuspid morphology. Materials and Methods Aortic 3D blood flow was evaluated by 4D flow MRI in 14 healthy volunteers with normal trileaflet valves and 14 patients withunicuspid(n=3), bicuspid (n=9, 3 ‘true’ bicuspid, 3 right-left (RL), 3 right-non (RN) coronary leaflet fusion, and quadricuspid aortic valves (n=2). Data analysis included the co-registered visualization of aortic valve morphology with systolic 3D blood flow. The influence of valve morphology on aortic hemodynamics was quantified by valve flow angle. Results All RL-BAV were associated with flow jets directed towards the right anterior aortic wallwhile RN-fusion and unicuspid valves resulted in flow jet patterns towards the right-posterior or posterior wall. Flow angles were clearly influenced by valve morphology(47°±10, 28°±2, 29°±18, 18°±12, 15°±2 for unicuspid, trueBAV, RN-BAV, RL-BAV, quadricuspid valves) and increased compared to controls (7.2°±1.1, p=0.001). Conclusions Altered 3D aortic hemodynamics are impacted by the morphology of congenitally malformed aortic valves. PMID:24265266

  12. Aortic root size and prevalence of aortic regurgitation in elite strength trained athletes.

    PubMed

    Babaee Bigi, Mohammad Ali; Aslani, Amir

    2007-08-01

    Athletes involved in mainly static or isometric exercise (e.g., weight lifting, power lifting, and bodybuilding) develop pressure overloads due to the high systemic arterial pressure found in this type of exercise. It is hypothesized that chronically elevated aortic wall tension in strength-trained athletes is associated with aortic dilatation and regurgitation. The aim of this study was to evaluate aortic root size and the prevalence of aortic regurgitation in elite strength-trained athletes. The cohort included 100 male athletes (mean age 22.1 +/- 3.6 years; all were finalists or medalists in the country) and 128 healthy age- and height-matched subjects (the control group). Aortic root diameters at end-diastole were measured at 4 locations: (1) the aortic annulus, (2) the sinuses of Valsalva, (3) the sinotubular junction, and (4) the maximal diameter of the proximal ascending aorta. Aortic root diameters at all levels were significantly greater in the strength-trained athletes (p <0.05 for all comparisons). When the strength-trained athletes were divided into quartiles of duration of high-intensity strength training (first quartile: <18 months; second quartile: >18 and <36 months; third quartile: >36 and <54 months; fourth quartile: >54 months), progressive enlargement was found at all aortic diameters. In conclusion, aortic root diameters in all segments of the aortic root were significantly greater in elite strength-trained athletes compared with an age- and height-matched population.

  13. Nontraumatic avulsion of aortic valve commissure as a cause of acute aortic valve regurgitation

    PubMed Central

    Chang, Rei-Yeuh; Chen, Chien-Chang; Hsu, Wei-Pang; Hsiao, Pei-Ching; Tsai, Han-Lin; Hsiao, Ping-Gune; Wu, Jiann-Der; Guo, How-Ran

    2016-01-01

    Abstract Background: Avulsion of the aortic valve commissure as a cause of acute aortic valve regurgitation is mostly due to trauma, infective endocarditis, or ascending aortic dissection. Nontraumatic avulsion of the aortic valve commissure is very rare. We reviewed the literature and analyzed potential risk factors of nontraumatic avulsion. Case presentation: An 80-year-old male with hypertension was seen in the emergency department with acute onset dyspnea. Echocardiogram revealed left ventricular hypertrophy with adequate systolic function, prolapse of the noncoronary cusp, and incomplete coaptation of the right coronary and noncoronary cusps with severe aortic valve regurgitation. Surgery revealed an avulsion between the left coronary and noncoronary cusps. Histopathology examination of the aortic valve showed myxoid degeneration, fibrosis, and calcification. Examination of the ascending aorta revealed myxoid degeneration and fragmentation of elastic fibers. Aortic valve replacement was performed, and the patient was alive and well 4 years after surgery. A review of the literature showed that more than three-fourths of the similar cases occurred in males, and about half in patients with hypertension and those 60 years of age or older. Conclusions: In the case of acute aortic regurgitation without a history of trauma, infection, or valvotomy, when 2 prolapsed aortic cusps are observed by echocardiography in the absence of an intimal tear of the ascending aorta, an avulsion of the aortic commissure should be suspected, especially in males with hypertension who are 60 years of age or older. PMID:27749570

  14. Optimizing Thomson's jumping ring

    NASA Astrophysics Data System (ADS)

    Tjossem, Paul J. H.; Brost, Elizabeth C.

    2011-04-01

    The height to which rings will jump in a Thomson jumping ring apparatus is the central question posed by this popular lecture demonstration. We develop a simple time-averaged inductive-phase-lag model for the dependence of the jump height on the ring material, its mass, and temperature and apply it to measurements of the jump height for a set of rings made by slicing copper and aluminum alloy pipe into varying lengths. The data confirm a peak jump height that grows, narrows, and shifts to smaller optimal mass when the rings are cooled to 77 K. The model explains the ratio of the cooled/warm jump heights for a given ring, the reduction in optimal mass as the ring is cooled, and the shape of the mass resonance. The ring that jumps the highest is found to have a characteristic resistance equal to the inductive reactance of the set of rings.

  15. Giant Thoracic Aneurysm Following Valve Replacement for Bicuspid Aortic Valve.

    PubMed

    Tran, Cao; Ul Haq, Ehtesham; Nguyen, Ngoc; Omar, Bassam

    2015-01-01

    Bicuspid aortic valve is a common congenital anomaly associated with aortopathy, which can cause aortic root dilatation, necessitating regular screening if the aortic root is > 4.0 cm. Despite the low absolute incidence of aortic complications associated with bicuspid aortic valve in the general population, the consequences of such complications for an individual patient can be devastating. Herein we propose a balanced algorithm that incorporates recommendations from the three major guidelines for follow-up imaging of the aortic root and ascending thoracic aorta in patients with a bicuspid aortic valve, maintaining the current recommendations with regard to surgical thresholds. PMID:26827748

  16. Comparison of magnetic resonance imaging of aortic valve stenosis and aortic root to multimodality imaging for selection of transcatheter aortic valve implantation candidates.

    PubMed

    Paelinck, Bernard P; Van Herck, Paul L; Rodrigus, Inez; Claeys, Marc J; Laborde, Jean-Claude; Parizel, Paul M; Vrints, Christiaan J; Bosmans, Johan M

    2011-07-01

    The purpose of the present study was to compare the aortic valve area, aortic valve annulus, and aortic root dimensions measured using magnetic resonance imaging (MRI) with catheterization, transthoracic echocardiography (TTE), and transesophageal echocardiography (TEE). An optimal prosthesis--aortic root match is an essential goal when evaluating patients for transcatheter aortic valve implantation. Comparisons between MRI and the other imaging techniques are rare and need validation. In 24 consecutive, high-risk, symptomatic patients with severe aortic stenosis, aortic valve area was prospectively determined using MRI and direct planimetry using three-dimensional TTE and calculated by catheterization using the Gorlin equation and by Doppler echocardiography using the continuity equation. Aortic valve annulus and the aortic root dimensions were prospectively measured using MRI, 2-dimensional TTE, and invasive aortography. In addition, aortic valve annulus was measured using TEE. No differences in aortic valve area were found among MRI, Doppler echocardiography, and 3-dimensional TTE compared with catheterization (p = NS). Invasive angiography underestimated aortic valve annulus compared with MRI (p <0.001), TEE (p <0.001), and 2-dimensional TTE (p <0.001). Two-dimensional TTE tended to underestimate the aortic valve annulus diameters compared to TEE and MRI. In contrast to 2-dimensional TTE, 3 patients had aortic valve annulus beyond the transcatheter aortic valve implantation range using TEE and MRI. In conclusion, MRI planimetry, Doppler, and 3-dimensional TTE provided an accurate estimate of the aortic valve area compared to catheterization. MRI and TEE provided similar and essential assessment of the aortic valve annulus dimensions, especially at the limits of the transcatheter aortic valve implantation range.

  17. Use of Circular Foldable Nitinol Blades for Resecting Calcified Aortic Heart Valves

    NASA Astrophysics Data System (ADS)

    Hauck, Florian; Wendt, Daniel; Stühle, Sebastian; Kawa, Emilia; Wendt, Hermann; Müller, Wiebke; Thielmann, Matthias; Kipfmüller, Brigitte; Vogel, Bernd; Jakob, Heinz

    2009-08-01

    The use of percutaneous aortic valve implantation is limited, as the native calcified valve is left in situ. A new device has been developed for resecting calcified aortic valves, using collapsible nickel-titanium blades: laser-cut T-structures of Nitinol sheet-material (Ni51Ti49 at.%) have been grinded on a high-speed milling cutter to produce cutting edges which have been given the shape of half-circles afterwards. These have been connected to each other and to struts by using rivets which also serve as articulating axes for the cutting ring. The blades are folded around these axes and retreated into a tube to be inserted in the heart through the calcified valve leaflets. Once released, the cutting edges regain their ring-shape. By combining rotation of the ring with a translating movement against a second ring of slightly greater diameter on the instrument, a punching process is created which cuts the calcified valve leaflets and leaves a circular annulus, where a prosthesis can be fixed. In vitro cutting of artificially calcified valves ( n = 6) resulted in a resection time of t = 22 ± 6.29 s with a maximum turning moment of M = 2.4 ± 1.27 Nm, proving the function and the feasibility of the concept.

  18. Decreased aortic glutathione levels may contribute to impaired nitric oxide-induced relaxation in hypercholesterolaemia

    PubMed Central

    Adachi, Takeshi; Cohen, Richard A

    2000-01-01

    The aim of this study was to determine if the decrease in aortic total glutathione (GSH) levels in hypercholesterolaemia is related to the impairment of relaxation to acetylcholine (ACh) and exogenous nitric oxide (NO). Isometric tension and vascular GSH levels were measured in thoracic aortic rings from rabbits fed for 12 weeks with 0.5% cholesterol diet. Hypercholesterolaemia decreased aortic GSH levels and impaired relaxation to ACh and NO. To determine if GSH depletion impaired the response to NO, normal rabbit thoracic aorta was incubated with 1,3-bis [2-chloroethyl]-1-nitrosourea (BCNU; 0.2 mmol L−1), a GSH reductase inhibitor, or diazine-dicarboxylic acid bis [N, N dimethylamide] (diamide; 1 mmol L−1), a thiol oxidizing agent. BCNU or diamide decreased aortic GSH levels and impaired ACh and NO-induced relaxation. The effects of diamide on GSH levels and relaxation were partially prevented by co-incubation with GSH ester (GSE; 2 mmol L−1). Increasing GSH with GSE significantly enhanced NO-induced relaxation in aorta from both hypercholesterolaemic and normal rabbits, however relaxation of hypercholesterolaemic rabbit aorta was not restored to normal. These data suggest that other factors, perhaps related to the long-term decrease in GSH levels, are responsible for reduced NO bioactivity in hypercholesterolaemia. PMID:10696103

  19. In vivo constriction of the fetal and neonatal ductus arteriosus by a prostanoid EP4-receptor antagonist in rats.

    PubMed

    Momma, Kazuo; Toyoshima, Katsuaki; Takeuchi, Daiji; Imamura, Shinichiro; Nakanishi, Toshio

    2005-11-01

    Indomethacin is used to constrict the patent ductus arteriosus in premature infants. To clarify possible prostanoid receptor antagonists that can constrict the ductus, we studied in vivo constriction of the fetal and neonatal ductus arteriosus by AE3-208, a prostanoid EP4-receptor antagonist, in rats. Following quick cesarean section of near-term pregnant rats (21 d), neonates were incubated in room air at 33 degrees C. The inner diameter of the ductus was measured with a microscope and a micrometer following rapid whole-body freezing of the fetus and neonate, and sectioning of the thorax in the frontal plane on a freezing microtome. In the control, the ductus arteriosus constricted quickly after birth, and the inner diameter was 0.80 mm in the fetus and 0.06 mm at 90 min after birth. AE3-208, administered orogastrically to the dam, constricted the fetal ductus dose dependently. Maximal ductal constriction was observed 4 h after administration, and the ductal diameters were 0.06 mm and 0.26 mm after administration of 10 mg/kg and 10 ng/kg of AE3-208, respectively. In neonatal rats, AE3-208 injected subcutaneously at 30 min after birth, inhibited dilatation of the ductus by PGE1 dose dependently. PGE1 (10 microg/kg) was injected subcutaneously to the 1-h-old neonatal rat, and the ductal diameters were 0.53 mm and 0.19 mm without and with pretreatment of AE3-208 (10 microg/kg), respectively. These results indicate the major role of EP4 in the fetal and neonatal ductus and show that an EP4 antagonist can be used to constrict the patent ductus of premature infants.

  20. Sources of activator calcium for potassium- and serotonin-induced constriction of isolated bovine cerebral arteries

    SciTech Connect

    Not Available

    1986-03-01

    Previous in vitro studies with the calcium channel blockers (CCB) indirectly suggest that K/sup +/ and serotonin (5HT) constrict bovine middle cerebral arteries (BMCA) by promoting the influx of extracellular calcium (Ca) through CCB-sensitive channels. In this study, the authors directly determined the sources of activator Ca for K/sup +/- and 5HT-induced constriction of BMCA, using radiolabelled /sup 4/)2%Ca and /sup 3/H-sorbitol. EGTA-resistant Ca uptake, an estimate of Ca influx into vascular smooth muscle, was determined by exposure to Ca-deficient 2 mM EGTA solutions at 1/sup 0/C. The total Ca content of BMCA was 4.4 nmole/mg (wet wt.) after equilibration at 37/sup 0/C. The total exchangeable Ca content was 1.64 nmole/mg after 1 hr of /sup 45/Ca loading; the Ca content of the extracellular water was 0.30 nmole/mg, as estimated from the /sup 3/H-sorbitol space (0.25 ul/mg). The EGTA-resistant Ca uptake at 1 hr was 134 pmole/mg. K/sup +/ and 5HT significantly increased EGTA-resistant Ca uptake during 5 min of /sup 45/Ca loading; for K/sup +/, Ca uptake increased from 71 to 202 pmole/mg, and for 5HT, from 65 to 102 pmole/mg. Verapamil (10/sup -5/ M) or nifedipine (3.3 x 10/sup -7/ M) significantly blocked the increase in EGTA-resistant Ca uptake induced by K/sup +/ or 5HT. These results provide direct evidence that K/sup +/ or 5HT may constrict BMCA by promoting the influx of extracellular Ca through CCB-sensitive channels.

  1. Piezoelectric control of the static behaviour of flextensional actuators with constricted hinges

    NASA Astrophysics Data System (ADS)

    Przybylski, Jacek

    2014-06-01

    The objective of this paper is to present the mathematical modelling and computational testing of the static operational performance and effectiveness of flextensional actuators comprised of two rectilinear or initially deflected beams placed equidistantly from a centrally located piezoceramic stack in the form of a rod. The beams are mounted by stiff links with an offset to a piezoelectric transformer. A monolithic hinge lever mechanism is applied by cutting constricted hinges at the links to generate and magnify the in-plane displacement created by the application of a voltage to the piezorod. Structures of such a type have been commonly used as passive or active actuators since the manufacturing of the mechanism’s prototypes in the form of Moonie or cymbal actuators. An analytical model of the actuator is developed on the basis of stationary values of the total potential energy principle with the use of the von Kármán non-linear strains theory. During the numerical computations, the deflection and internal axial force generated by both the externally distributed load and the the application of an electric field are determined by changing the actuator properties such as the distance between the beams and the rod, the amplitude of the beam’s initial displacement as well as the stiffness of the constricted hinges. Additionally, the application of structure prestressing is considered to avoid an undesired stretching of the piezo stack. It has been shown that for the flextensional actuator with a very high flexibility of constricted hinges, the generated transverse displacement is limited by the maximum electric field as the characteristic property for each piezoceramic material. A vast number of numerical results exhibit the mechanical responses of the transducer of different geometrical and physical properties to piezoelectric stimulation; this has potential applications in the design process of such actuators.

  2. Anomalous origin of the left innominate (brachiocephalic) artery in the right aortic arch: How can it be anomalous when the left innominate artery is absent?

    PubMed Central

    Raimondi, Francesca; Bonnet, Damien; Geva, Tal; Sanders, Stephen P

    2016-01-01

    An unusual case of a rare vascular ring, which has been called right aortic arch with aberrant left innominate artery, is presented. The appearance of this case led to the realization that there is really no innominate artery present in this anomaly but only the left dorsal aorta. We present a clarification of the nature and likely development of the vessels present. PMID:27212855

  3. The Effects of Positioning of Transcatheter Aortic Valve on Fluid Dynamics of the Aortic Root

    PubMed Central

    Su, Jimmy L; Kheradvar, Arash

    2015-01-01

    Transcatheter aortic valve implantation is a novel treatment for severe aortic valve stenosis. Due to the recent use of this technology and the procedural variability, there is very little data that quantifies the hemodynamic consequences of variations in valve placement. Changes in aortic wall stresses and fluid retention in the sinuses of Valsalva can have a significant effect on the clinical response a patient has to the procedure. By comprehensively characterizing complex flow in the sinuses of Valsalva using Digital Particle Image Velocimetry and an advanced heart flow simulator, various positions of a deployed transcatheter valve with respect to a bioprosthetic aortic valve (valve-in-valve) were tested in vitro. Displacements of the transcatheter valve were axial and directed below the simulated native valve annulus. It was determined that for both blood residence time and aortic Reynolds stresses, it is optimal to have the annulus of the transcatheter valve deployed as close to the aortic valve annulus as possible. PMID:25010918

  4. Pathology specific secondary aortic interventions after thoracic endovascular aortic repair

    PubMed Central

    Scali, Salvatore T.; Beck, Adam W.; Butler, Khayree; Feezor, Robert J.; Martin, Tomas D.; Hess, Philip J.; Huber, Thomas S.; Chang, Catherine K.

    2014-01-01

    Objective: Despite improved short-term outcomes, concerns remain regarding durability of thoracic endovascular aortic repair(TEVAR). The purpose of this analysis was to evaluate the pathology-specific incidence of secondary aortic interventions(SAI) after TEVAR and their impact on survival. Methods: Retrospective review was performed of all TEVAR procedures and SAI at one institution from 2004-2011. Kaplan-Meier analysis was used to estimate survival. Results: Of 585 patients, 72(12%) required SAI at a median of 5.6 months(interquartile range(IQR):1.4-14.2) with 22(3.7%) requiring multiple SAI. SAI incidence differed significantly by pathology(P=.002): acute dissection(21.3%), post-surgical(20.0%), chronic dissection(16.7%), degenerative aneurysm(10.8%), traumatic transection(8.1%), penetrating ulcer(1.5%), and other etiologies(14.8%). Most common indications after dissection were persistent false lumen flow and proximal/distal extension of disease. For degenerative aneurysms, SAI was performed primarily to treat type I/III endoleaks. SAI patients had a greater mean number of comorbidities(P<.0005), stents placed(P=.0002), and postoperative complications after the index TEVAR(P<.0005) compared to those without SAI. Freedom from SAI at 1 and 5 years(95% CI) was estimated to be 86%(82-90%) and 68%(57-76%), respectively. There were no differences in survival(95% CI) between patients requiring SAI and those who did not: SAI 1-year: 88%(77-93%), 5-year: 51%(37-63%) and no SAI 1-year: 82%(79-85%), 5-year: 67%(62-71%)(Log-rank P=0.2). Conclusion: SAI after TEVAR is not uncommon, particularly in patients with dissection, but does not affect long-term survival. Aortic pathology is the most important variable impacting survival and dictated need, timing and mode of SAI. The varying incidence of SAI by indication underscores the need for diligent surveillance protocols that should be pathology-specific. PMID:24571937

  5. Vascular ring (image)

    MedlinePlus

    Vascular ring is a term used to describe a number of abnormal formations of the aorta, the large artery ... the pulmonary artery. The abnormal vessel(s) forms a ring, which encircles and may press down on the ...

  6. New dust belts of Uranus: one ring, two ring, red ring, blue ring.

    PubMed

    de Pater, Imke; Hammel, Heidi B; Gibbard, Seran G; Showalter, Mark R

    2006-04-01

    We compared near-infrared observations of the recently discovered outer rings of Uranus with Hubble Space Telescope results. We find that the inner ring, R/2003 U 2, is red, whereas the outer ring, R/2003 U 1, is very blue. Blue is an unusual color for rings; Saturn's enigmatic E ring is the only other known example. By analogy to the E ring, R/2003 U 1 is probably produced by impacts into the embedded moon Mab, which apparently orbits at a location where nongravitational perturbations favor the survival and spreading of submicron-sized dust. R/2003 U 2 more closely resembles Saturn's G ring, which is red, a typical color for dusty rings. PMID:16601188

  7. New dust belts of Uranus: one ring, two ring, red ring, blue ring.

    PubMed

    de Pater, Imke; Hammel, Heidi B; Gibbard, Seran G; Showalter, Mark R

    2006-04-01

    We compared near-infrared observations of the recently discovered outer rings of Uranus with Hubble Space Telescope results. We find that the inner ring, R/2003 U 2, is red, whereas the outer ring, R/2003 U 1, is very blue. Blue is an unusual color for rings; Saturn's enigmatic E ring is the only other known example. By analogy to the E ring, R/2003 U 1 is probably produced by impacts into the embedded moon Mab, which apparently orbits at a location where nongravitational perturbations favor the survival and spreading of submicron-sized dust. R/2003 U 2 more closely resembles Saturn's G ring, which is red, a typical color for dusty rings.

  8. Transcatheter aortic valve implantation: anesthetic considerations.

    PubMed

    Billings, Frederic T; Kodali, Susheel K; Shanewise, Jack S

    2009-05-01

    Aortic valvular stenosis remains the most common debilitating valvular heart lesion. Despite the benefit of aortic valve (AV) replacement, many high-risk patients cannot tolerate surgery. AV implantation treats aortic stenosis without subjecting patients to sternotomy, cardiopulmonary bypass (CPB), and aorta cross-clamping. This transcatheter procedure is performed via puncture of the left ventricular (LV) apex or percutaneously, via the femoral artery or vein. Patients undergo general anesthesia, intense hemodynamic manipulation, and transesophageal echocardiography (TEE). To elucidate the role of the anesthesiologist in the management of transcatheter AV implantation, we review the literature and provide our experience, focusing on anesthetic care, intraoperative events, TEE, and perioperative complications. Two approaches to the aortic annulus are performed today: transfemoral retrograde and transapical antegrade. Iliac artery size and tortuosity, aortic arch atheroma, and pathology in the area of the (LV) apex help determine the preferred approach in each patient. A general anesthetic is tailored to achieve extubation after procedure completion, whereas IV access and pharmacological support allow for emergent sternotomy and initiation of CPB. Rapid ventricular pacing and cessation of mechanical ventilation interrupts cardiac ejection and minimizes heart translocation during valvuloplasty and prosthesis implantation. Although these maneuvers facilitate exact prosthesis positioning within the native annulus, they promote hypotension and arrhythmia. Vasopressor administration before pacing and cardioversion may restore adequate hemodynamics. TEE determines annulus size, aortic pathology, ventricular function, and mitral regurgitation. TEE and fluoroscopy are used for positioning the introducer catheter within the aortic annulus. The prosthesis, crimped on a valvuloplasty balloon catheter, is implanted by inflation. TEE immediately measures aortic regurgitation and

  9. Endovascular Repair of Thoracic Aortic Aneurysms

    PubMed Central

    Findeiss, Laura K.; Cody, Michael E.

    2011-01-01

    Degenerative aneurysms of the thoracic aorta are increasing in prevalence; open repair of descending thoracic aortic aneurysms is associated with high rates of morbidity and mortality. Repair of isolated descending thoracic aortic aneurysms using stent grafts was introduced in 1995, and in an anatomically suitable subgroup of patients with thoracic aortic aneurysm, repair with endovascular stent graft provides favorable outcomes, with decreased perioperative morbidity and mortality relative to open repair. The cornerstones of successful thoracic endovascular aneurysm repair are appropriate patient selection, thorough preprocedural planning, and cautious procedural execution, the elements of which are discussed here. PMID:22379281

  10. Giant aortic arch aneurysm complicating Kawasaki's disease

    PubMed Central

    Hakim, Kaouthar; Boussada, Rafik; Chaker, Lilia; Ouarda, Fatma

    2014-01-01

    Kawasaki disease (KD) is a common acute vasculitis in pediatric population that usually involves small- and middle-sized arteries, commonly coronary arteries. Although the incidence and natural course of coronary aneurysms after KD are well documented in studies, related reports on peripheral arterial and aortic aneurysms are scarce. We report the occurrence of a giant aortic aneurysm involving the horizontal part of aortic arch in a 28-month-old boy diagnosed with KD. This complication was managed by steroids therapy in the beginning. Because of mechanical complication and potential risk of rupture, surgery was undertaken. PMID:25298695

  11. Bacillus cereus endocarditis in native aortic valve.

    PubMed

    Ngow, H A; Wan Khairina, W M N

    2013-02-01

    Bacillus cereus endocarditis is rare. It has been implicated in immunocompromised individuals, especially in intravenous drug users as well as in those with a cardiac prosthesis. The patient was a 31-year-old ex-intravenous drug addict with a past history of staphylococcal pulmonary valve endocarditis, who presented with symptoms of decompensated cardiac failure. Echocardiography showed severe aortic regurgitation with an oscillating vegetation seen on the right coronary cusp of the aortic valve. The blood cultures grew Bacillus cereus. We report this as a rare case of Bacillus cereus endocarditis affecting a native aortic valve.

  12. Saturn's F-Ring

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This narrow-angle camera image of Saturn's F Ring was taken through the Clear filter while at a distance of 6.9 million km from Saturn on 8 November 1980. The brightness variations of this tightly-constrained ring shown here indicate that the ring is less uniform in makeup than the larger rings. JPL managed the Voyager Project for NASA's Office of Space Science

  13. MRCK-1 Drives Apical Constriction in C. elegans by Linking Developmental Patterning to Force Generation.

    PubMed

    Marston, Daniel J; Higgins, Christopher D; Peters, Kimberly A; Cupp, Timothy D; Dickinson, Daniel J; Pani, Ariel M; Moore, Regan P; Cox, Amanda H; Kiehart, Daniel P; Goldstein, Bob

    2016-08-22

    Apical constriction is a change in cell shape that drives key morphogenetic events including gastrulation and neural tube formation. Apical force-producing actomyosin networks drive apical constriction by contracting while connected to cell-cell junctions. The mechanisms by which developmental patterning regulates these actomyosin networks and associated junctions with spatial precision are not fully understood. Here we identify a myosin light-chain kinase MRCK-1 as a key regulator of C. elegans gastrulation that integrates spatial and developmental patterning information. We show that MRCK-1 is required for activation of contractile actomyosin dynamics and elevated cortical tension in the apical cell cortex of endoderm precursor cells. MRCK-1 is apically localized by active Cdc42 at the external, cell-cell contact-free surfaces of apically constricting cells, downstream of cell fate determination mechanisms. We establish that the junctional components α-catenin, β-catenin, and cadherin become highly enriched at the apical junctions of apically constricting cells and that MRCK-1 and myosin activity are required in vivo for this enrichment. Taken together, our results define mechanisms that position a myosin activator to a specific cell surface where it both locally increases cortical tension and locally enriches junctional components to facilitate apical constriction. These results reveal crucial links that can tie spatial information to local force generation to drive morphogenesis. PMID:27451898

  14. The physical nature of the phenomenon of positive column plasma constriction in low-pressure noble gas direct current discharges

    SciTech Connect

    Kurbatov, P. F.

    2014-02-15

    The essence of the positive-column plasma constriction for static (the diffusion mode) and dynamic ionization equilibrium (the stratificated and constricted modes) is analyzed. Two physical parameters, namely, the effective ionization rate of gas atoms and the ambipolar diffusion coefficient of electrons and ions, determine the transverse distribution of discharge species and affect the current states of plasma. Transverse constriction of the positive column takes place as the gas ionization level (discharge current) and pressure increase. The stratified mode (including the constricted one) is observed between the two adjacent types of self-sustained discharge phases when they coexist together at the same time or in the same place as a coherent binary mixture. In the case, a occurrence of the discharge phase with more high electron density presently involve a great decrease in the cross-section of the current channel for d.c. discharges. Additional physical factors, such as cataphoresis and electrophoresis phenomena and spatial gas density inhomogeneity correlated with a circulatory flow in d.c. discharges, are mainly responsible for the current hysteresis and partially constricted discharge.

  15. Management of Traumatic Aortic and Splenic Rupture in a Patient With Ascending Aortic Aneurysm.

    PubMed

    Topcu, Ahmet Can; Ciloglu, Ufuk; Bolukcu, Ahmet; Dagsali, Sabri

    2016-08-01

    Traumatic aortic rupture is rupture of all or part of the aortic wall, mostly resulting from blunt trauma to the chest. The most common site of rupture is the aortic isthmus. Traumatic rupture of the ascending aorta is rare. A 62-year-old man with a family history of ascending aortic aneurysm was referred to our hospital after a motor vehicle accident. He had symptoms of cardiogenic shock. A contrast-enhanced computed tomographic scan revealed rupture of the proximal ascending aorta and an ascending aortic aneurysm with a diameter of 55 mm at the level of the sinuses of Valsalva. Transthoracic echocardiography at the bedside revealed severe aortic valvular insufficiency. We performed a successful Bentall procedure. During postoperative recovery, the patient experienced a cerebrovascular accident. Transesophageal echocardiography did not reveal thrombosis of the mechanical prosthesis. The patient's symptoms resolved in time, and he was discharged from the hospital on postoperative day 47 without any sequelae. He has been symptom free during a 6-month follow-up period. We suggest that individuals who have experienced blunt trauma to the chest and have symptoms of traumatic aortic rupture and a known medical history of ascending aortic aneurysm should be evaluated for a rupture at the ascending aorta and the aortic isthmus. PMID:27449463

  16. Descending aortic dissection injured by tip of the sheath during transcatheter aortic valve implantation.

    PubMed

    Nagasawa, Atsushi; Shirai, Shinichi; Hanyu, Michiya; Arai, Yoshio; Kamioka, Norihiko; Hayashi, Masaomi

    2016-04-01

    An 86-year-old woman was referred for transcatheter aortic valve implantation (TAVI) because of recurrent severe aortic stenosis after balloon aortic valvuloplasty in May 2014. We planned to implant a 23-mm Sapien XT valve by transfemoral approach. During procedure, aortic dissection was detected by transesophageal echocardiography (TEE). The dissection limited to the descending aorta and did not include the ascending aorta. Therefore, our team decided to implant the 23-mm Sapien valve as planned. After the procedure, the dissection was treated conservatively without surgical repair. Three weeks later, she was discharged without any complications.

  17. Flaxseed oil increases aortic reactivity to phenylephrine through reactive oxygen species and the cyclooxygenase-2 pathway in rats

    PubMed Central

    2014-01-01

    Background Flaxseed oil has the highest concentration of omega-3 α-linolenic acid, which has been associated with cardiovascular benefit. However, the mechanism underlying the vascular effects induced through flaxseed oil is not well known. Thus, in the present study, we investigated the effects of flaxseed oil on vascular function in isolated rat aortic rings. Methods Wistar rats were treated daily with flaxseed oil or a control (mineral oil) intramuscular (i.m.) for fifteen days. Isolated aortic segments were used to evaluate cyclooxygenase-2 (COX-2) protein expression, superoxide anion levels and vascular reactivity experiments. Results Flaxseed oil treatment increased the vasoconstrictor response of aortic rings to phenylephrine. Endothelium removal increased the response to phenylephrine in aortic segments isolated from both groups, but the effect was smaller in the treated group. L-NAME incubation similarly increased the phenylephrine response in segments from both groups. The TXA2 synthase inhibitor furegrelate, the selective COX-2 inhibitor NS 398, the TP receptor antagonist SQ 29.548, the reactive oxygen species (ROS) scavenger apocynin, the superoxide anion scavengers tiron and the phospholipase A2 inhibitor dexamethasone partially reversed the flaxseed oil-induced increase in reactivity to phenylephrine. Conclusions These findings suggest that flaxseed oil treatment increased vascular reactivity to phenylephrine through an increase in ROS production and COX-2-derived TXA2 production. The results obtained in the present study provide new insight into the effects of flaxseed oil treatment (i.m.) on vascular function. PMID:24993607

  18. The Jumping Ring Experiment

    ERIC Educational Resources Information Center

    Baylie, M.; Ford, P. J.; Mathlin, G. P.; Palmer, C.

    2009-01-01

    The jumping ring experiment has become central to liquid nitrogen shows given as part of the outreach and open day activities carried out within the University of Bath. The basic principles of the experiment are described as well as the effect of changing the geometry of the rings and their metallurgical state. In general, aluminium rings are…

  19. Rings Around Uranus

    ERIC Educational Resources Information Center

    Maran, Stephen P.

    1977-01-01

    Events leading up to the discovery of the rings of Uranus are described. The methods used and the logic behind the methods are explained. Data collected to prove the existence of the rings are outlined and theories concerning the presence of planetary rings are presented. (AJ)

  20. Antinociceptive activity of astragaloside IV in the animal model of chronic constriction injury.

    PubMed

    Shi, Guo-Bing; Fan, Rong; Zhang, Wei; Yang, Chen; Wang, Qi; Song, Juan; Gao, Yue; Hou, Ming-Xiao; Chen, Yu-Feng; Wang, Tong-Chao; Cai, Guo-Jun

    2015-08-01

    To investigate the applicability of astragaloside IV (AG) for the treatment of refractory neuropathic pain, we systemically evaluated the antinociceptive activity of AG in the animal model of chronic constriction injury. We studied behaviors, electrophysiology, and biochemistry from day 2 to day 23 after the surgery. We found that when administered intraperitoneally at the dose of 60 mg/kg, AG caused significant inhibition of allodynia and hyperalgesia induced by mechanic and thermal stimuli as well as downregulation of the expressions of a series of proteins involved in mediating neuropathic pain in the dorsal root ganglia, such as P2X purinoceptor 3, glial cell-derived neurotrophic factor, glial cell-derived neurotrophic factor family receptor α1, and transient receptor potential cation channel subtypes A1 and V1. Further investigation showed that AG restored the nerve conduction velocity and the histological structure of the damaged sciatic nerve on day 23 after the surgery. Moreover, results from immunoelectron microscope showed that glial cell-derived neurotrophic factor family receptor α1 induced by AG could form a circular band in the myelin debris between the injured axons and Schwann cells, contributing toward restoration of the damaged nerve. In conclusion, in our animal model, AG effectively inhibited the neuropathic pain induced by chronic constriction injury.

  1. Apical constriction drives tissue-scale hydrodynamic flow to mediate cell elongation

    PubMed Central

    He, Bing; Doubrovinski, Konstantin; Polyakov, Oleg; Wieschaus, Eric

    2014-01-01

    Epithelial folding mediated by apical constriction converts flat epithelial sheets into multilayered, complex tissue structures and is employed throughout the development in most animals1. Little is known, however, how forces produced near the apical surface of the tissue are transmitted within individual cells to generate the global changes in cell shape that characterize tissue deformation. Here we apply particle tracking velocimetry in gastrulating Drosophila embryos to measure the movement of cytoplasm and plasma membrane during ventral furrow (VF) formation2, 3. We find that cytoplasmic redistribution during the lengthening phase of VF formation can be precisely described by viscous flows that quantitatively match the predictions of hydrodynamics. Cell membranes move with the ambient cytoplasm, with little resistance to or driving force on the flow. Strikingly, apical constriction produces similar flow patterns in mutant embryos that fail to form cells prior to gastrulation (“acellular” embryos), such that the global redistribution of cytoplasm mirrors the summed redistribution occurring in individual cells of wild type embryos. Our results suggest that during the lengthening phase of VF formation, hydrodynamic behavior of the cytoplasm provides the predominant mechanism transmitting apically generated forces deep into the tissue and that cell individualization is dispensable. PMID:24590071

  2. Effusive-constrictive calcific pericarditis associated with Streptococcus salivarius. Case report and review of the literature.

    PubMed

    Rafailidis, Petros I; Prapas, Sotirios N; Kasiakou, Sofia K; Costeas, Xenofon F; Falagas, Matthew E

    2005-01-01

    We report the case of a 40-year-old patient presenting with a 6-month history of dyspnea and edema, with significant worsening of his clinical manifestations for the 2 weeks before admission to our department. During this 14-day preadmission period, continuous positive airway pressure (CPAP) was prescribed elsewhere for management of a working diagnosis of obstructive sleep apnea. The patient presented to us hemodynamically compromised. Management of the patient included emergency cardiac surgery for tamponade caused by effusive-constrictive, calcific pericarditis in addition to antimicrobial treatment as a result of the growth of Streptococcus salivarius from the pericardial fluid. This is the first report in the literature of association of this microorganism with pericarditis. The use of CPAP made the patient's symptoms worse as a result of an increase of the intrathoracic pressure, which was a pathophysiological mechanism, added to the interference of the localized pericardial effusion and the effect of the pericardial constriction. In an era of rapidly increasing use of CPAP systems, clinicians should be aware of their possible detrimental effects on patients with some types of cardiopulmonary diseases. PMID:15831142

  3. Probing weak localization in chemical vapor deposition graphene wide constriction using scanning gate microscopy

    NASA Astrophysics Data System (ADS)

    Chuang, C.; Matsunaga, M.; Liu, F.-H.; Woo, T.-P.; Aoki, N.; Lin, L.-H.; Wu, B.-Y.; Ochiai, Y.; Liang, C.-T.

    2016-02-01

    Low-temperature scanning gate microscopy (LT-SGM) studies of graphene allow one to obtain important spatial information regarding coherent transport such as weak localization (WL) and universal conductance fluctuations. Although fascinating LT-SGM results on pristine graphene prepared by mechanical exfoliation have been reported in the literature, there appears to be a dearth of LT-SGM results on chemical vapor deposition (CVD)-grown graphene whose large scale and flexible substrate transferability make it an ideal candidate for coherent electronic applications. To this end, we have performed LT-SGM studies on CVD-grown graphene wide constriction (0.8 μm), which can be readily prepared by cost-effective optical lithography fully compatible with those in wafer foundry, in the WL regime. We find that the movable local gate can sensitively modulate the total conductance of the CVD graphene constriction possibly due to the intrinsic grain boundaries and merged domains, a great advantage for applications in coherent electronics. Moreover, such a conductance modulation by LT-SGM provides an additional, approximately magnetic-field-independent probe for studying coherent transport such as WL in graphene and spatial conductance variation.

  4. Gabapentin attenuates neuropathic pain and improves nerve myelination after chronic sciatic constriction in rats.

    PubMed

    Câmara, Carlos C; Araújo, Celina V; de Sousa, Kalina Kelma Oliveira; Brito, Gerly A C; Vale, Mariana L; Raposo, Ramon da Silva; Mendonça, Fabiana Evaristo; Mietto, Bruno S; Martinez, Ana Maria B; Oriá, Reinaldo B

    2015-10-21

    Gabapentin (GBP) is an anti-convulsive drug often used as analgesic to control neuropathic pain. This study aimed at evaluating oral GBP treatment (30, 60, 120 mg/kg, 60 min prior to chronic constriction of the sciatic nerve (CCSN) along 15-day treatment post-injury, 12 h/12 h) by monitoring spontaneous and induced-pain behaviors in Wistar rats on 5th and 15th days post-injury during early neuropathic events. CCSN animals receiving saline were used as controls. Another aim of this study was to evaluate GBP effects on myelin basic protein (MBP) on the 5th and 15th days post-injury and nerve morphology by transmission electron microscopy to address nerve regeneration. On the 5th and 15th days, GBP (60 mg/kg) reduced neuropathic pain behaviors (scratching and biting) in the ipsilateral paw and alleviated mechanical allodynia in comparison with the neuropathic saline group. GBP significantly increased climbing and rearing behaviors in CCSN and CCSN-free animals suggesting increased motor activity rather than sedation. We found three-fold significant increase in MBP expression by western blots on the 15th day when compared to controls. In addition, GPB (60 mg/kg) improved nerve axonal, fiber and myelin area 15 days post-surgery. In conclusion, GBP alleviated mechanical and thermal allodynia and spontaneous pain-related behaviors and improved later nerve morphology. Our findings suggest that GBP improve nerve remyelination after chronic constriction of the sciatic nerve.

  5. Stretch-induced changes in constricted lung parenchymal strips: role of extracellular matrix.

    PubMed

    Salerno, F G; Fust, A; Ludwig, M S

    2004-02-01

    Large amplitude oscillations of contracted airway smooth muscle cause relative relaxation of the preparation. However, little is known about the effect of mechanical stretch on distal lung behaviour. Rat parenchymal strips were suspended in an organ bath and attached at one end to a force transducer and at the other end to a servo-controlled lever arm that effected length changes. Mechanical impedance of the strip was measured by applying a complex signal consisting of pseudorandom length oscillations of varying frequencies (0.5-19.75 Hz). A constant phase model was fit to changes in length and tension to calculate tissue damping (G) and elastance (H). Hysteresivity was calculated as G/H. Impedance was measured before and after sinusoidal length oscillation at different amplitudes (1, 3, 10 and 25% of resting length) at a frequency of 1 Hz under baseline conditions and after acetylcholine-induced constriction. Oscillations of 10 and 25% amplitudes significantly decreased the G and H of the lung strip. The effect of length oscillations was no different in control versus constricted strips. These data suggest that in the distal lung, large stretches affect the structural components of the extracellular matrix rather than the contractile elements. PMID:14979490

  6. Intraneural dexamethasone applied simultaneously to rat sciatic nerve constriction delays the development of hyperalgesia and allodynia.

    PubMed

    Bastos, Leandro F S; Medeiros, Daniel C; Vieira, Rafael P; Watkins, Linda R; Coelho, Márcio M; Moraes, Márcio F D

    2012-02-21

    Although neuroimmune interactions associated with the development of pain sensitization in models of neuropathic pain have been widely studied, there are some aspects that require further investigation. Thus, we aimed to evaluate whether the local intraneural or perineural injections of dexamethasone, an efficacious anti-inflammatory and immunosuppressant drug, delays the development of both thermal hyperalgesia and mechanical allodynia in an experimental model of neuropathic pain in rats. Hargreaves and electronic von Frey tests were applied. The chronic constriction injury (CCI) of right sciatic nerve was performed. Single intraneural dexamethasone administration at the moment of constriction delayed the development of sensitization for thermal hyperalgesia and mechanical allodynia. However, perineural administration of dexamethasone, at the highest dose, did not delay experimental pain development. These results show that inflammation/immune response at the site of nerve lesion is an essential trigger for the pathological changes that lead to both hyperalgesia and allodynia. In conclusion, this approach opens new opportunities to study cellular and molecular neuroimmune interactions associated with the development of pain derived from peripheral neuropathies. PMID:22240103

  7. Effects of vascular constriction on occlusive thrombus formation of rat mesenteric artery.

    PubMed

    Araki, H; Nishi, K

    1986-10-01

    Effects of vascular constriction on thrombotic occlusion was evaluated using rat mesenteric arteries and video-recording system attached to the microscope. Topical application of norepinephrine of 1, 10 and 100 micrograms/ml reduced the arterial diameter dose dependently from 297 +/- 41 mu to 166 +/- 50, 87 +/- 18 and 84 +/- 11 mu (mean +/- SD, n = 7), respectively. The diameter reduction by the higher 2 doses persisted for more than 30 minutes until the wash out of the agent. But, no thrombus formation was observed. A reproducible thrombus formation was induced by inserting a glass micropipette into the vascular lumen. The maximal percent occlusion by the thrombus was 80 +/- 11% (range; 67 to 95%, n = 7). The topical application of 10 micrograms/ml norepinephrine induced vasoconstriction and increased the percent occlusion significantly to 97 +/- 8% (p less than 0.05). Complete occlusion of the lumen developed in 6 of 7 rats after the agent and in 2 rats it was not released until the wash out of the agent for more than 30 minutes. Thrombus formation itself did not change the arterial diameter at the site of thrombus formation as well as at sites of 300 and 600 mu down stream. It is suggested that the vascular constriction alone does not necessarily cause thrombus formation but may aggravate the arterial flow reduction induced by thrombosis.

  8. Immune reactions in tuberculous and chronic constrictive pericarditis. Clinical data and diagnostic significance of antimyocardial antibodies.

    PubMed

    Maisch, B; Maisch, S; Kochsiek, K

    1982-11-01

    Humoral immune reactions were analyzed in 12 patients with exudative tuberculous pericarditis, 10 patients with constrictive pericarditis due to former tuberculosis, 10 patients with viral pericarditis, 20 patients with pulmonary tuberculosis, and 98 healthy donors. Pericarditis occurred in 12.5% of the patients with tuberculosis, whereas the incidence of tuberculosis in the 149 patients with pericarditis was 8%. Repeated pericardial puncture and pericardial effusions of greater than 500 ml with impending cardiac tamponade had to be performed in 4 patients. Clinical data indicated probable myocardial involvement in 4 of 12 patients. Antimyolemmal antibodies, which are a muscle-specific subtype of antisarcolemmal antibodies, were found in all patients with exudative tuberculous pericarditis and viral perimyocarditis, in only 1 of 12 patients with constrictive pericarditis, and in no patients with pulmonary tuberculosis. Antifibrillary antibodies--primarily of the antimyosin type--were missed in patients with viral heart disease but were demonstrated in 75% of patients with tuberculous pericarditis. Only sera with complement-fixing antimyolemmal antibodies of the IgG type in titers greater than 1:40 induced cytolysis of vital adult heterologous cardiocytes isolated and enriched by silica sol gradient centrifugation. These findings suggest not only that antimyolemmal antibodies are diagnostic indicators of perimyocardial involvement in tuberculous pericarditis, but also that they may play a significant role in its pathogenesis. PMID:6753555

  9. Arm-ankle systolic blood pressure difference at rest and after exercise in the assessment of aortic coarctation.

    PubMed Central

    Engvall, J.; Sonnhag, C.; Nylander, E.; Stenport, G.; Karlsson, E.; Wranne, B.

    1995-01-01

    OBJECTIVE--To evaluate the difference in systolic blood pressure at the arm and ankle at rest and after various exercise tests for the assessment of aortic coarctation. METHODS--22 patients (mean age 33 years, range 17-66) were investigated on the suspicion of having haemodynamically significant aortic coarctation. Eight had undergone previous coarctation surgery, of whom five had received vascular grafts and three end to end anastomoses. The patients exercised submaximally while supine, seated on a bicycle, and walking on a treadmill, as well as exercising maximally on a treadmill. Arm and ankle blood pressure were measured with a cuff at rest and 1-10 minutes after exercise. Invasive pressures and cardiac output by thermodilution were recorded during catheterisation while patients were at rest and during and after supine bicycle exercise. The degree of constriction was assessed by angiography. Twelve healthy volunteers (mean age 32 years, range 17-56) provided reference values for cuff pressures after exercise. RESULTS--All patients with a difference in cuff pressure at rest of 35 mm Hg or more had a difference in invasive pressure of 35 mm Hg or more. Increasing severity of constriction on angiography correlated with larger pressure gradients at rest and during exercise (P < 0.0001). When cuff measurements after exercise were considered singly or combined to form a predictor they did not improve the prediction of the invasive pressure gradients at rest or after maximal exercise. A pressure gradient between arm and ankle also developed in normal subjects after maximal but not after submaximal exercise. CONCLUSION--In most patients with suspected haemodynamically significant coarctation the difference in cuff pressure between arm and ankle at rest is sufficient to select patients in need of further evaluation. If exercise is performed submaximal exercise is preferable. PMID:7727189

  10. SUBCOMMISSURAL IMPLANTATION OF AORTIC PROSTHESES WITH THE USE OF THE NONCORONARY SINUS AND THE FIBROUS TRIGONES

    PubMed Central

    Liotta, Domingo; Haller, Jordan D.; Pisanu, Amadeo; Bracco, Daniel; Bertolozzi, Enrique

    1979-01-01

    The technique described here permits insertion of a large prosthesis into a small aortic annulus and avoids the necessity of additional procedures for enlarging the aortic ring. Inspection of the fibrous skeleton of the heart reveals that the large intervalvular trigone and the noncoronary sinus of Valsalva are remarkably elastic. Full advantage of this natural elasticity is achieved by suturing the prosthesis to the base of these structures from outside the aorta. Sutures are placed in the sinuses of the right and left cusps in the usual manner. Judicious application of this procedure allows the implantation of a No. 23 or No. 24 prosthesis in cases that would require a No. 19 or No. 21 with the use of conventional methods. Images PMID:15216322

  11. The fission yeast cytokinetic contractile ring regulates septum shape and closure

    PubMed Central

    Thiyagarajan, Sathish; Munteanu, Emilia Laura; Arasada, Rajesh; Pollard, Thomas D.; O'Shaughnessy, Ben

    2015-01-01

    ABSTRACT During cytokinesis, fission yeast and other fungi and bacteria grow a septum that divides the cell in two. In fission yeast closure of the circular septum hole by the β-glucan synthases (Bgs) and other glucan synthases in the plasma membrane is tightly coupled to constriction of an actomyosin contractile ring attached to the membrane. It is unknown how septum growth is coordinated over scales of several microns to maintain septum circularity. Here, we documented the shapes of ingrowing septum edges by measuring the roughness of the edges, a measure of the deviation from circularity. The roughness was small, with spatial correlations indicative of spatially coordinated growth. We hypothesized that Bgs-mediated septum growth is mechanosensitive and coupled to contractile ring tension. A mathematical model showed that ring tension then generates almost circular septum edges by adjusting growth rates in a curvature-dependent fashion. The model reproduced experimental roughness statistics and showed that septum synthesis sets the mean closure rate. Our results suggest that the fission yeast cytokinetic ring tension does not set the constriction rate but regulates septum closure by suppressing roughness produced by inherently stochastic molecular growth processes. PMID:26240178

  12. The antimetastatic drug NAMI-A potentiates the phenylephrine-induced contraction of aortic smooth muscle cells and induces a transient increase in systolic blood pressure.

    PubMed

    Vadori, M; Florio, C; Groppo, B; Cocchietto, M; Pacor, S; Zorzet, S; Candussio, L; Sava, G

    2015-07-01

    The ruthenium-based drug imidazolium trans-imidazoledimethylsulphoxidetetrachlorido ruthenate (NAMI-A) is a novel antitumour drug under clinical evaluation. In this study, NAMI-A is tested on aortic rings in vitro and on the systolic blood pressure in vivo with the aim of evaluating its effects on smooth muscle cells and, more in general, on the vascular system. Pre-incubation of aortic rings with 10 µM NAMI-A for 10 min potentiates the contraction induced by phenylephrine (PE). The reduction of the B max value of [(3)H]-prazosin bound to NAMI-A-treated aortic rings and the ability of NAMI-A to displace [(3)H]-prazosin and [(3)H]-IP3 binding by 25 and 42%, respectively, suggest the involvement of α1-adrenoceptor in mediating the effects on smooth muscle cells. NAMI-A also decreases the number of maximal sites of [(3)H]-prazosin bound to kidney membrane preparation from 34 to 24 fmol/mg proteins. A single i.p. dose (105 mg/kg) or a repeated treatment for 6 consecutive days (17 mg/kg/day) in Wistar rats increases the systolic blood pressure, respectively, 1 h and 3 days after treatment, and the responsiveness of rat aortic rings to PE. Atomic absorption spectroscopy confirms the presence of ruthenium in the aortic rings excised from the treated rats. These findings suggest monitoring the cardiovascular parameters when the drug is used in humans for treating cancer patients, particularly if the drug is associated with chemicals that are potentially active at the cardiovascular level.

  13. Dahl SS rats demonstrate enhanced aortic perivascular adipose tissue-mediated buffering of vasoconstriction through activation of NOS in the endothelium.

    PubMed

    Spradley, Frank T; Ho, Dao H; Pollock, Jennifer S

    2016-02-01

    Perivascular adipose tissue (PVAT) mediates buffering of vasoconstriction through activation of endothelium-derived factors. We hypothesized that the PVAT of Dahl salt-sensitive (Dahl SS) rats has reduced ability to buffer vasoconstriction. Vascular reactivity experiments were performed on aortic rings with PVAT intact (+PVAT) or removed (-PVAT), and endothelium intact (+ENDO) or removed (-ENDO) from Dahl SS rats and control SS.13(BN) rats (Dahl SS rats that have had chromosome 13 completely replaced with that of the Brown Norway rat, rendering this strain insensitive to high-salt or high-fat diet-induced hypertension). Endothelial dysfunction, assessed by ACh-mediated vasorelaxation, was confirmed in aortic rings of Dahl SS rats. The +PVAT+ENDO aortic rings had indistinguishable phenylephrine-induced vasoconstriction between genotypes. In both strains, removal of PVAT significantly enhanced vasoconstriction. Dahl SS rat -PVAT+ENDO aortic rings displayed exaggerated vasoconstriction to phenylephrine vs. SS.13(BN) rats, indicating that PVAT-mediated buffering of vasoconstriction was greater in Dahl SS rats. Removal of both the ENDO and PVAT restored vasoconstriction in both strains. The nitric oxide synthase (NOS) inhibitor, N(ω)-nitro-L-arginine methyl ester (L-NAME), produced a similar effect as that seen with -ENDO. These data indicate that the function of the PVAT to activate endothelium-derived NOS is enhanced in Dahl SS compared with SS.13(BN) rats and, most likely, occurs through a pathway that is distinct from ACh-mediated activation of NOS. PVAT weight and total PVAT leptin levels were greater in Dahl SS rats. Leptin induced a significantly decreased vasoconstriction in -PVAT+ENDO aortic rings from Dahl SS rats, but not SS.13(BN) rats. In contrast to our initial hypothesis, PVAT in Dahl SS rats buffers vasoconstriction by activating endothelial NOS via mechanisms that may include the involvement of leptin. Thus, the PVAT serves a vasoprotective role in

  14. Dahl SS rats demonstrate enhanced aortic perivascular adipose tissue-mediated buffering of vasoconstriction through activation of NOS in the endothelium.

    PubMed

    Spradley, Frank T; Ho, Dao H; Pollock, Jennifer S

    2016-02-01

    Perivascular adipose tissue (PVAT) mediates buffering of vasoconstriction through activation of endothelium-derived factors. We hypothesized that the PVAT of Dahl salt-sensitive (Dahl SS) rats has reduced ability to buffer vasoconstriction. Vascular reactivity experiments were performed on aortic rings with PVAT intact (+PVAT) or removed (-PVAT), and endothelium intact (+ENDO) or removed (-ENDO) from Dahl SS rats and control SS.13(BN) rats (Dahl SS rats that have had chromosome 13 completely replaced with that of the Brown Norway rat, rendering this strain insensitive to high-salt or high-fat diet-induced hypertension). Endothelial dysfunction, assessed by ACh-mediated vasorelaxation, was confirmed in aortic rings of Dahl SS rats. The +PVAT+ENDO aortic rings had indistinguishable phenylephrine-induced vasoconstriction between genotypes. In both strains, removal of PVAT significantly enhanced vasoconstriction. Dahl SS rat -PVAT+ENDO aortic rings displayed exaggerated vasoconstriction to phenylephrine vs. SS.13(BN) rats, indicating that PVAT-mediated buffering of vasoconstriction was greater in Dahl SS rats. Removal of both the ENDO and PVAT restored vasoconstriction in both strains. The nitric oxide synthase (NOS) inhibitor, N(ω)-nitro-L-arginine methyl ester (L-NAME), produced a similar effect as that seen with -ENDO. These data indicate that the function of the PVAT to activate endothelium-derived NOS is enhanced in Dahl SS compared with SS.13(BN) rats and, most likely, occurs through a pathway that is distinct from ACh-mediated activation of NOS. PVAT weight and total PVAT leptin levels were greater in Dahl SS rats. Leptin induced a significantly decreased vasoconstriction in -PVAT+ENDO aortic rings from Dahl SS rats, but not SS.13(BN) rats. In contrast to our initial hypothesis, PVAT in Dahl SS rats buffers vasoconstriction by activating endothelial NOS via mechanisms that may include the involvement of leptin. Thus, the PVAT serves a vasoprotective role in

  15. Valve selection in aortic valve endocarditis

    PubMed Central

    Zubrytska, Yana

    2016-01-01

    Aortic prosthetic valve endocarditis (PVE) is a potentially life-threatening disease. Mortality and incidence of infective endocarditis have been reduced in the past 30 years. Medical treatment of aortic PVE may be successful in patients who have a prompt response after antibiotic treatment and who do not have prosthetic dysfunction. In advanced stages, antibiotic therapy alone is insufficient to control the disease, and surgical intervention is necessary. Surgical treatment may be lifesaving, but it is still associated with considerable morbidity and mortality. The aim of surgery is to perform a radical excision of all infected and necrotic tissue, reconstruction of the left ventricle outflow tract, and replacement of the aortic valve. There is no unanimous consensus on which is the optimal prosthesis to implant in this context, and several surgical techniques have been suggested. We aim to analyze the efficacy of the surgical treatment and discuss the issue of valve selection in patients with aortic valve endocarditis. PMID:27785132

  16. A rare cause of recurrent aortic dissection.

    PubMed

    Agrawal, Yashwant; Gupta, Vishal

    2016-07-01

    We report the case of a 19-year-old man with a history of Loeys-Dietz syndrome (LDS), which was diagnosed when he had a Stanford type A aortic dissection. He also had multiple aneurysms including ones in the innominate, right common carotid, and right internal mammary arteries. He had had multiple procedures including Bentall's procedure, repeat sternotomy with complete arch and valve replacement, and coil embolization of internal mammary artery aneurysm in the past. His LDS was characterized by gene mutation for transforming growth factor-β receptor 1. He presented to our facility with sudden onset of back pain, radiating to the right shoulder and chest. He was diagnosed with Stanford type B aortic dissection and underwent thoracic aorta endovascular repair for his aortic dissection. This case represents the broad spectrum of pathology associated with LDS where even with regular surveillance and aggressive medical management the patient developed Stanford B aortic dissection. PMID:27358537

  17. The diagnosis and management of aortic dissection.

    PubMed

    Karthikesalingam, A; Holt, P J E; Hinchliffe, R J; Thompson, M M; Loftus, I M

    2010-04-01

    Aortic dissection represents the most common aortic emergency, affecting 3 to 4 per 100,000 people per year and is still associated with a high mortality. Twenty percent of the patients with aortic dissection die before reaching hospital and 30% die during hospital admission. Aortic dissections may be classified in 3 ways: according to their anatomical extent (the Stanford or DeBakey systems), according to the time from onset (acute or chronic), and according to the underlying pathology (the European Society of Cardiologists' system). Advances in endovascular technology have provided new treatment options. Hybrid endovascular and conventional open surgical repair represent the mainstay of treatment for acute type A dissection. Medical management remains the gold standard for acute and uncomplicated chronic type B dissection, though endovascular surgery offers exciting potential in the management of complicated type B dissection through sealing of the intimal entry tear.

  18. Nanobacteria-associated calcific aortic valve stenosis.

    PubMed

    Jelic, Tomislav M; Chang, Ho-Huang; Roque, Rod; Malas, Amer M; Warren, Stafford G; Sommer, Andrei P

    2007-01-01

    Calcific aortic valve stenosis is the most common valvular disease in developed countries, and the major reason for operative valve replacement. In the US, the current annual cost of this surgery is approximately 1 billion dollars. Despite increasing morbidity and mortality, little is known of the cellular basis of the calcifications, which occur in high-perfusion zones of the heart. The case is presented of a patient with calcific aortic valve stenosis and colonies of progressively mineralized nanobacteria in the fibrocalcific nodules of the aortic cusps, as revealed by transmission electron microscopy. Consistent with their outstanding bioadhesivity, nanobacteria might serve as causative agents in the development of calcific aortic valve stenosis. PMID:17315391

  19. Saturn's largest ring.

    PubMed

    Verbiscer, Anne J; Skrutskie, Michael F; Hamilton, Douglas P

    2009-10-22

    Most planetary rings in the Solar System lie within a few radii of their host body, because at these distances gravitational accelerations inhibit satellite formation. The best known exceptions are Jupiter's gossamer rings and Saturn's E ring, broad sheets of dust that extend outward until they fade from view at five to ten planetary radii. Source satellites continuously supply the dust, which is subsequently lost in collisions or by radial transport. Here we report that Saturn has an enormous ring associated with its outer moon Phoebe, extending from at least 128R(S) to 207R(S) (Saturn's radius R(S) is 60,330 km). The ring's vertical thickness of 40R(S) matches the range of vertical motion of Phoebe along its orbit. Dynamical considerations argue that these ring particles span the Saturnian system from the main rings to the edges of interplanetary space. The ring's normal optical depth of approximately 2 x 10(-8) is comparable to that of Jupiter's faintest gossamer ring, although its particle number density is several hundred times smaller. Repeated impacts on Phoebe, from both interplanetary and circumplanetary particle populations, probably keep the ring populated with material. Ring particles smaller than centimetres in size slowly migrate inward and many of them ultimately strike the dark leading face of Iapetus.

  20. Transfemoral aortic valve implantation in severe aortic stenosis patients with prior mitral valve prosthesis

    PubMed Central

    Sarı, Cenk; Baştuğ, Serdal; Kasapkara, Hacı Ahmet; Durmaz, Tahir; Keleş, Telat; Akçay, Murat; Aslan, Abdullah Nabi; Bayram, Nihal Akar; Bozkurt, Engin

    2015-01-01

    Introduction Transcatheter aortic valve implantation for severe symptomatic aortic stenosis in patients with a previous mitral valve prosthesis is technically challenging, and pre-procedural comprehensive assessment of these patients before transcatheter aortic valve implantation is vital for an uncomplicated and successful procedure. Aim We want to share our experience with transcatheter aortic valve implantation in patients with a preexisting functional mitral valve prosthesis and describe a series of important technical and pre-procedural details. Material and methods At our center, 135 patients with symptomatic severe aortic stenosis were treated with transcatheter aortic valve implantation. Six of them with a preexisting mitral valve prosthesis received an Edwards SAPIEN XT valve through the transfemoral route. Results Transcatheter aortic valve implantation was performed successfully in all 6 patients without any deformation of the cobalt-chromium/steel stents of the aortic valve bioprosthesis. Also no distortion or malfunction in the mitral valve prosthesis was observed after the procedure. There were no complications during the hospitalization period. Post-procedural echocardiography revealed no or mild aortic paravalvular regurgitation and normal valve function in all the patients. In addition, serial echocardiographic examination demonstrated that both the stability and function of the aortic and mitral prosthetic valves were normal without any deterioration in the gradients and the degree of the regurgitation at long-term follow-ups. Conclusions Our experience confirms that transcatheter aortic valve implantation is technically feasible in patients with previous mitral valve replacement but comprehensive evaluation of patients by multimodal imaging techniques such as transesophageal echocardiography and multislice computed tomography is mandatory for a successful and safe procedure. PMID:26677380

  1. Peripartum presentation of an acute aortic dissection.

    PubMed

    Lewis, S; Ryder, I; Lovell, A T

    2005-04-01

    We report the case of an acute type A aortic dissection occurring in a 35-year-old parturient. The initial diagnosis was missed; a subsequent emergency Caesarean section 3 weeks after presentation was followed by the development of left ventricular failure and pulmonary oedema in the early postoperative period. Echocardiography confirmed the diagnosis of aortic dissection and the patient underwent a successful surgical repair.

  2. Abdominal Aortic Aneurysmectomy in Renal Transplant Patients

    PubMed Central

    Jebara, Victor A.; Fabiani, Jean-Noël; Moulonguet-Deloris, L.; Acar, Christophe; Debauchez, Mathieu; Chachques, J.C.; Glotz, Denis; Duboust, Alain; Langanay, Thierry; Carpentier, Alain

    1990-01-01

    Because renal transplantation is allowing an increased number of patients to survive for prolonged periods, abdominal aortic aneurysms can be expected to occur with growing frequency in these patients. Surgical management of such cases involves the provision of allograft protection. To date, the literature contains 15 reports of abdominal aortic aneurysms in renal allograft recipients. We describe a 16th case and discuss the management of these patients. (Texas Heart Institute Journal 1990;17:240-4) Images PMID:15227179

  3. Peripartum presentation of an acute aortic dissection.

    PubMed

    Lewis, S; Ryder, I; Lovell, A T

    2005-04-01

    We report the case of an acute type A aortic dissection occurring in a 35-year-old parturient. The initial diagnosis was missed; a subsequent emergency Caesarean section 3 weeks after presentation was followed by the development of left ventricular failure and pulmonary oedema in the early postoperative period. Echocardiography confirmed the diagnosis of aortic dissection and the patient underwent a successful surgical repair. PMID:15640303

  4. Juxtarenal aortic aneurysm: endoluminal transfemoral repair?

    PubMed

    Ferko, A; Krajina, A; Jon, B; Lesko, M; Voboril, Z; Zizka, J; Eliás, P

    1997-01-01

    Endoluminal transfemoral repair of an abdominal aortic aneurysm by a stent graft placement requires a segment of the nondilated infrarenal aorta of at least 15 mm long for safe stent graft attachment. The possibility of endoluminal treatment of a juxtarenal abdominal aortic aneurysm with partially covered spiral Z stent was assessed in experiment and in three clinical cases. In the experiment, the noncovered spiral Z stent was placed into the abdominal aorta, across the origins of renal arteries and mesenteric arteries, in six dogs. In the clinical cases, a partially covered stent graft was attached in 3 patients with the juxtarenal abdominal aortic aneurysm (of the group of 12 patients with abdominal aortic aneurysm). The stent grafts were attached with proximal uncovered parts across the origins of the renal arteries. In experiment, the renal artery occlusions or stenoses were not observed 36 months after stent placement, and in clinic, 3 patients with the juxtarenal aortic aneurysm were successfully treated by stent graft placement. There were no signs of flow impairment into the renal arteries 14 months after stent graft implantation. This approach can possibly expand the indications for endoluminal grafting in the treatment of juxtarenal aortic aneurysms in patients who are at high risk for surgery.

  5. Quantification of abdominal aortic deformation after EVAR

    NASA Astrophysics Data System (ADS)

    Demirci, Stefanie; Manstad-Hulaas, Frode; Navab, Nassir

    2009-02-01

    Quantification of abdominal aortic deformation is an important requirement for the evaluation of endovascular stenting procedures and the further refinement of stent graft design. During endovascular aortic repair (EVAR) treatment, the aortic shape is subject to severe deformation that is imposed by medical instruments such as guide wires, catheters, and, the stent graft. This deformation can affect the flow characteristics and morphology of the aorta which have been shown to be elicitors for stent graft failures and be reason for reappearance of aneurysms. We present a method for quantifying the deformation of an aneurysmatic aorta imposed by an inserted stent graft device. The outline of the procedure includes initial rigid alignment of the two abdominal scans, segmentation of abdominal vessel trees, and automatic reduction of their centerline structures to one specified region of interest around the aorta. This is accomplished by preprocessing and remodeling of the pre- and postoperative aortic shapes before performing a non-rigid registration. We further narrow the resulting displacement fields to only include local non-rigid deformation and therefore, eliminate all remaining global rigid transformations. Finally, deformations for specified locations can be calculated from the resulting displacement fields. In order to evaluate our method, experiments for the extraction of aortic deformation fields are conducted on 15 patient datasets from endovascular aortic repair (EVAR) treatment. A visual assessment of the registration results and evaluation of the usage of deformation quantification were performed by two vascular surgeons and one interventional radiologist who are all experts in EVAR procedures.

  6. Chloroplast Division Protein ARC3 Regulates Chloroplast FtsZ-Ring Assembly and Positioning in Arabidopsis through Interaction with FtsZ2[C][W

    PubMed Central

    Zhang, Min; Schmitz, Aaron J.; Kadirjan-Kalbach, Deena K.; TerBush, Allan D.; Osteryoung, Katherine W.

    2013-01-01

    Chloroplast division is initiated by assembly of a mid-chloroplast FtsZ (Z) ring comprising two cytoskeletal proteins, FtsZ1 and FtsZ2. The division-site regulators ACCUMULATION AND REPLICATION OF CHLOROPLASTS3 (ARC3), MinD1, and MinE1 restrict division to the mid-plastid, but their roles are poorly understood. Using genetic analyses in Arabidopsis thaliana, we show that ARC3 mediates division-site placement by inhibiting Z-ring assembly, and MinD1 and MinE1 function through ARC3. ftsZ1 null mutants exhibited some mid-plastid FtsZ2 rings and constrictions, whereas neither constrictions nor FtsZ1 rings were observed in mutants lacking FtsZ2, suggesting FtsZ2 is the primary determinant of Z-ring assembly in vivo. arc3 ftsZ1 double mutants exhibited multiple parallel but no mid-plastid FtsZ2 rings, resembling the Z-ring phenotype in arc3 single mutants and showing that ARC3 affects positioning of FtsZ2 rings as well as Z rings. ARC3 overexpression in the wild type and ftsZ1 inhibited Z-ring and FtsZ2-ring assembly, respectively. Consistent with its effects in vivo, ARC3 interacted with FtsZ2 in two-hybrid assays and inhibited FtsZ2 assembly in a heterologous system. Our studies are consistent with a model wherein ARC3 directly inhibits Z-ring assembly in vivo primarily through interaction with FtsZ2 in heteropolymers and suggest that ARC3 activity is spatially regulated by MinD1 and MinE1 to permit Z-ring assembly at the mid-plastid. PMID:23715471

  7. Direct aortic transcatheter valve implantation in a porcelain aorta.

    PubMed

    Bruschi, Giuseppe; Botta, Luca; De Marco, Federico; Colombo, Paola; Klugmann, Silvio; Martinelli, Luigi

    2014-10-01

    Transcatheter aortic valve implantation has been designed to treat elderly patients with severe aortic stenosis at high risk for surgery, and is generally performed retrogradely with vascular access. However, in certain patients, this access is either not possible or deemed to carry a high risk of vascular injury. We report our experience of a direct aortic approach in a 78-year old man with severe aortic stenosis, excluded from standard aortic valve replacement due to a porcelain aorta, and affected by severe aortic, iliac-femoral, and subclavian arteriopathy, rendering the transfemoral or subclavian approach unemployable.

  8. Chest radiography in acute aortic syndrome: pearls and pitfalls.

    PubMed

    Chawla, Ashish; Rajendran, Surendran; Yung, Wai Heng; Babu, Suresh Balasubramanian; Peh, Wilfred C

    2016-08-01

    Acute aortic syndrome is a group of life-threatening diseases of the thoracic aorta that usually present to the emergency department. It includes aortic dissection, aortic intramural hematoma, and penetrating aortic ulcer. Rare aortic pathologies of aorto-esophageal fistula and mycotic aneurysm may also be included in this list. All these conditions require urgent treatment with complex clinical care and management. Most patients who present with chest pain are evaluated with a chest radiograph in the emergency department. It is important that maximum diagnostic information is extracted from the chest radiograph as certain signs on the chest radiograph are extremely useful in pointing towards the diagnosis of acute aortic syndrome.

  9. Valve sparing: aortic root replacement with the reimplantation technique.

    PubMed

    Mastrobuoni, Stefano; Tamer, Sadallah; de Kerchove, Laurent; El Khoury, Gebrine

    2015-01-01

    Aortic valve-sparing procedures are alternative options to aortic valve replacement in patients with aortic root aneurysm and/or severe aortic regurgitation reducing the risk of prosthesis-related complications, such as thromboembolism, and have no need for long-term oral anticoagulation. However, these techniques are technically demanding and long-term results are highly dependent on perfect intraoperative restoration of valve function. We describe a systematic approach to aortic valve-sparing aortic root replacement with the reimplantation technique the way it is currently performed in our institution. PMID:26137865

  10. Aortic root dissection. Another cause of early systolic closure of the aortic valve.

    PubMed Central

    Candell-Riera, J; del Castillo, H G; Rius, J

    1980-01-01

    An early systolic closure of the aortic valve was recorded in the echocardiogram in two patients with aortic root dissection. This sign, initially described in discrete subaortic stenosis and occasionally observed in mitral regurgitation and interventricular septal defect, has not so far been described in dissecting aneurysm of the aorta. Images PMID:7378219

  11. Dust and Planetary Rings

    NASA Astrophysics Data System (ADS)

    Siddiqui, Muddassir

    ABSTRACT Space is not empty it has comic radiations (CMBR), dust etc. Cosmic dust is that type of dust which is composed of particles in space which vary from few molecules to 0.1micro metres in size. This type of dust is made up of heavier atoms born in the heart of stars and supernova. Mainly it contains dust grains and when these dust grains starts compacting then it turns to dense clouds, planetary ring dust and circumstellar dust. Dust grains are mainly silicate particles. Dust plays a major role in our solar system, for example in zodiacal light, Saturn's B ring spokes, planetary rings at Jovian planets and comets. Observations and measurements of cosmic dust in different regions of universe provide an important insight into the Universe's recycling processes. Astronomers consider dust in its most recycled state. Cosmic dust have radiative properties by which they can be detected. Cosmic dusts are classified as intergalactic dusts, interstellar dusts and planetary rings. A planetary ring is a ring of cosmic dust and other small particles orbiting around a planet in flat disc shape. All of the Jovian planets in our solar system have rings. But the most notable one is the Saturn's ring which is the brightest one. In March 2008 a report suggested that the Saturn's moon Rhea may have its own tenuous ring system. The ring swirling around Saturn consists of chunks of ice and dust. Most rings were thought to be unstable and to dissipate over course of tens or hundreds of millions of years but it now appears that Saturn's rings might be older than that. The dust particles in the ring collide with each other and are subjected to forces other than gravity of its own planet. Such collisions and extra forces tend to spread out the rings. Pluto is not known to have any ring system but some Astronomers believe that New Horizons probe might find a ring system when it visits in 2015.It is also predicted that Phobos, a moon of Mars will break up and form into a planetary ring

  12. [Surgical Outcomes of Aortic Root Repair in Type A Acute Aortic Dissection].

    PubMed

    Okamoto, Yuki; Yamamoto, Kazuo; Asami, Fuyuki; Kimura, Mitsuhiro; Mizumoto, Masahiro; Okubo, Yuka; Takesue, Yuki; Yoshii, Sinpei

    2016-04-01

    We carried out a retrospective evaluation of the early and long-term outcomes of aortic root reconstruction for type A acute aortic dissection. Between January 2001 and March 2015, a total of 21 patients underwent aortic root reconstruction. Bentall operation was performed in 9 patients( B group) and Patch plasty of sinus of Valsalva patients was performed in 12 patients (V group). There were 3 in-hospital deaths due in the B group and 1 death due in the V group. Overall survival in the V group was 72.9% and was not significantly different from survival in the B group(66.7%). In conclusion, our study demonstrated good early and long-term outcomes for patch plasty of sinus of Valsalva for type A acute aortic dissection. There was no postoperative patch-related complication in the V group. Thus, a patch plasty of sinus of Valsalva for type A acute aortic issection may be acceptable. PMID:27210253

  13. Combined surgical and catheter-based treatment of extensive thoracic aortic aneurysm and aortic valve stenosis.

    PubMed

    De Backer, Ole; Lönn, Lars; Søndergaard, Lars

    2015-02-15

    An extensive thoracic aortic aneurysm (TAA) is a potentially life-threatening condition and remains a technical challenge to surgeons. Over the past decade, repair of aortic arch aneurysms has been accomplished using both hybrid (open and endovascular) and totally endovascular techniques. Thoracic endovascular aneurysm repair (TEVAR) has changed and extended management options in thoracic aorta disease, including in those patients deemed unfit or unsuitable for open surgery. Accordingly, transcatheter aortic valve replacement (TAVR) is increasingly used to treat patients with symptomatic severe aortic valve stenosis (AS) who are considered at high risk for surgical aortic valve replacement. In this report, we describe the combined surgical and catheter-based treatment of an extensive TAA and AS. To our knowledge, this is the first report of hybrid TAA repair combined with TAVR.

  14. Calmodulin Promotes N-BAR Domain-Mediated Membrane Constriction and Endocytosis.

    PubMed

    Myers, Margaret D; Ryazantsev, Sergey; Hicke, Linda; Payne, Gregory S

    2016-04-18

    Membrane remodeling by BAR (Bin, Amphiphysin, RVS) domain-containing proteins, such as endophilins and amphiphysins, is integral to the process of endocytosis. However, little is known about the regulation of endocytic BAR domain activity. We have identified an interaction between the yeast Rvs167 N-BAR domain and calmodulin. Calmodulin-binding mutants of Rvs167 exhibited defects in endocytic vesicle release. In vitro, calmodulin enhanced membrane tubulation and constriction by wild-type Rvs167 but not calmodulin-binding-defective mutants. A subset of mammalian N-BAR domains bound calmodulin, and co-expression of calmodulin with endophilin A2 potentiated tubulation in vivo. These studies reveal a conserved role for calmodulin in regulating the intrinsic membrane-sculpting activity of endocytic N-BAR domains.

  15. Experimental proof of faster-is-slower in systems of frictional particles flowing through constrictions.

    PubMed

    Pastor, José M; Garcimartín, Angel; Gago, Paula A; Peralta, Juan P; Martín-Gómez, César; Ferrer, Luis M; Maza, Diego; Parisi, Daniel R; Pugnaloni, Luis A; Zuriguel, Iker

    2015-12-01

    The "faster-is-slower" (FIS) effect was first predicted by computer simulations of the egress of pedestrians through a narrow exit [D. Helbing, I. J. Farkas, and T. Vicsek, Nature (London) 407, 487 (2000)]. FIS refers to the finding that, under certain conditions, an excess of the individuals' vigor in the attempt to exit causes a decrease in the flow rate. In general, this effect is identified by the appearance of a minimum when plotting the total evacuation time of a crowd as a function of the pedestrian desired velocity. Here, we experimentally show that the FIS effect indeed occurs in three different systems of discrete particles flowing through a constriction: (a) humans evacuating a room, (b) a herd of sheep entering a barn, and (c) grains flowing out a 2D hopper over a vibrated incline. This finding suggests that FIS is a universal phenomenon for active matter passing through a narrowing.

  16. Experimental proof of faster-is-slower in systems of frictional particles flowing through constrictions

    NASA Astrophysics Data System (ADS)

    Pastor, José M.; Garcimartín, Angel; Gago, Paula A.; Peralta, Juan P.; Martín-Gómez, César; Ferrer, Luis M.; Maza, Diego; Parisi, Daniel R.; Pugnaloni, Luis A.; Zuriguel, Iker

    2015-12-01

    The "faster-is-slower" (FIS) effect was first predicted by computer simulations of the egress of pedestrians through a narrow exit [D. Helbing, I. J. Farkas, and T. Vicsek, Nature (London) 407, 487 (2000), 10.1038/35035023]. FIS refers to the finding that, under certain conditions, an excess of the individuals' vigor in the attempt to exit causes a decrease in the flow rate. In general, this effect is identified by the appearance of a minimum when plotting the total evacuation time of a crowd as a function of the pedestrian desired velocity. Here, we experimentally show that the FIS effect indeed occurs in three different systems of discrete particles flowing through a constriction: (a) humans evacuating a room, (b) a herd of sheep entering a barn, and (c) grains flowing out a 2D hopper over a vibrated incline. This finding suggests that FIS is a universal phenomenon for active matter passing through a narrowing.

  17. Berberine Ameliorates Allodynia Induced by Chronic Constriction Injury of the Sciatic Nerve in Rats.

    PubMed

    Kim, Hyun Jee

    2015-08-01

    The objective of this study was to investigate whether berberine could ameliorate allodynia induced by chronic constriction injury (CCI) of the sciatic nerve in rats. After inducement of CCI, significant increases in the number of paw lifts from a cold plate test (cold allodynia) and decreased paw withdrawal threshold in the von Frey hair stimulation test (mechanical allodynia) were observed. However, these cold and mechanical allodynia were markedly alleviated by berberine administration in a dose-dependent manner. Sciatic nerve myeloperoxidase and malondialdehyde activities were also attenuated by berberine administration. Continuous injection for 7 days induced no development of tolerance. The antiallodynic effect of 20 mg/kg berberine was comparable to that of amitriptyline 10 mg/kg. This study demonstrated that berberine could mitigate allodynia induced by CCI, a neuropathic pain model, and it suggested that the anti-inflammatory and antioxidative properties of berberine contributed to the antiallodynic effect in the CCI model.

  18. Experimental proof of faster-is-slower in systems of frictional particles flowing through constrictions.

    PubMed

    Pastor, José M; Garcimartín, Angel; Gago, Paula A; Peralta, Juan P; Martín-Gómez, César; Ferrer, Luis M; Maza, Diego; Parisi, Daniel R; Pugnaloni, Luis A; Zuriguel, Iker

    2015-12-01

    The "faster-is-slower" (FIS) effect was first predicted by computer simulations of the egress of pedestrians through a narrow exit [D. Helbing, I. J. Farkas, and T. Vicsek, Nature (London) 407, 487 (2000)]. FIS refers to the finding that, under certain conditions, an excess of the individuals' vigor in the attempt to exit causes a decrease in the flow rate. In general, this effect is identified by the appearance of a minimum when plotting the total evacuation time of a crowd as a function of the pedestrian desired velocity. Here, we experimentally show that the FIS effect indeed occurs in three different systems of discrete particles flowing through a constriction: (a) humans evacuating a room, (b) a herd of sheep entering a barn, and (c) grains flowing out a 2D hopper over a vibrated incline. This finding suggests that FIS is a universal phenomenon for active matter passing through a narrowing. PMID:26764754

  19. [General anesthesia with remifentanil for a patient having sinoatrial block and constrictive pulmonary disorder].

    PubMed

    Nishio, Yumiko; Hara, Koji; Obara, Goh; Sata, Takeyoshi

    2008-08-01

    There is little report describing the effect of remifentanil on cardiac conduction system. We present a successful anesthetic management with remifentanil in a patient with sick sinus syndrome. A 66-year-old woman (31-kg, 121-cm) having sinoatrial (SA) block was diagnosed as having hepatic cell carcinoma, and radiofrequency ablation (RFA) was scheduled. She was also suffering from kyphosis due to the past history of tuberculous spondylitis. Preoperative examination of her respiratory function indicated a severe constrictive pulmonary disorder. Anesthesia was induced with propofol (30 mg), and maintained with sevoflurane (1-2%) and oxygen/air in combination with remifentanil (0.5 microg x kg(-1) x min(-1)). Temporary pacemaker was prepared during anesthesia. Neither remifentanil nor sevoflurane deteriorated SA block and her heart rate was well controlled. Respiratory dysfunction was not seen in the postoperative course. Our case suggests that remifentanil may be a suitable analgesic for patients with cardiac conduction abnormalities.

  20. Berberine Ameliorates Allodynia Induced by Chronic Constriction Injury of the Sciatic Nerve in Rats.

    PubMed

    Kim, Hyun Jee

    2015-08-01

    The objective of this study was to investigate whether berberine could ameliorate allodynia induced by chronic constriction injury (CCI) of the sciatic nerve in rats. After inducement of CCI, significant increases in the number of paw lifts from a cold plate test (cold allodynia) and decreased paw withdrawal threshold in the von Frey hair stimulation test (mechanical allodynia) were observed. However, these cold and mechanical allodynia were markedly alleviated by berberine administration in a dose-dependent manner. Sciatic nerve myeloperoxidase and malondialdehyde activities were also attenuated by berberine administration. Continuous injection for 7 days induced no development of tolerance. The antiallodynic effect of 20 mg/kg berberine was comparable to that of amitriptyline 10 mg/kg. This study demonstrated that berberine could mitigate allodynia induced by CCI, a neuropathic pain model, and it suggested that the anti-inflammatory and antioxidative properties of berberine contributed to the antiallodynic effect in the CCI model. PMID:25674823

  1. On multiple Einstein rings

    NASA Astrophysics Data System (ADS)

    Werner, M. C.; An, J.; Evans, N. W.

    2008-12-01

    A number of recent surveys for gravitational lenses have found examples of double Einstein rings. Here, we analytically investigate the occurrence of multiple Einstein rings. We prove, under very general assumptions, that at the most one Einstein ring can arise from a mass distribution in a single plane lensing a single background source. Two or more Einstein rings can therefore only occur in multiplane lensing. Surprisingly, we show that it is possible for a single source to produce more than one Einstein ring. If two point masses, or two isothermal spheres, in different planes are aligned with observer and source on the optical axis, we show that there are up to three Einstein rings. We also discuss the image morphologies for these two models if axisymmetry is broken, and give the first instances of magnification invariants in the case of two-lens planes.

  2. Evaluating Effects of Floodplain Constriction Along a High Energy Gravel-Bed River: Snake River, WY

    NASA Astrophysics Data System (ADS)

    Leonard, Christina M.

    This study examined approximately 66 km of the Snake River, WY, USA, spanning a natural reach within Grand Teton National Park and a reach immediately downstream that is confined by artificial levees. We linked the channel adjustments observed within these two reaches between 2007 and 2012 to sediment transport processes by developing a morphological sediment budget. A pair of digital elevation models (DEMs) was generated by fusing LiDAR topography with depth estimates derived from optical image data within wetted channels. Errors for both components of the DEMs (LiDAR and optical bathymetry) were propagated through the DEM of difference and sediment budget calculations. Our results indicated that even with the best available methods for acquiring high resolution topographic data over large areas, the uncertainty associated with bed elevation estimates implied that net volumetric changes were not statistically significant. In addition to the terrain analysis, we performed a tracer study to assess the mobility of different grain size classes in different morphological units. Grain sizes, hydraulic conditions, and flow resistance characteristics along cross-sections were used to calculate critical discharges for entrainment, but this bulk characterization of fluid driving forces failed to predict bed mobility. Our results indicated that over seasonal timescales specific grain classes were not preferentially entrained. Surface and subsurface grain size data were used to calculate armoring and dimensionless sediment transport ratios for both reaches; sediment supply exceeded transport capacity in the natural reach and vice versa in the confined reach. We used a conceptual model to describe channel adjustments to lateral constriction by levees. Initially we suggest levees focused flow energy and incised the bed, resulting in bed armoring. Bed armoring promoted channel widening, but levees prevented this and instead the channel migrated more rapidly within the

  3. Dendritic atrophy constricts functional maps in resonance and impedance properties of hippocampal model neurons

    PubMed Central

    Dhupia, Neha; Rathour, Rahul K.; Narayanan, Rishikesh

    2015-01-01

    A gradient in the density of hyperpolarization-activated cyclic-nucleotide gated (HCN) channels is necessary for the emergence of several functional maps within hippocampal pyramidal neurons. Here, we systematically analyzed the impact of dendritic atrophy on nine such functional maps, related to input resistance and local/transfer impedance properties, using conductance-based models of hippocampal pyramidal neurons. We introduced progressive dendritic atrophy in a CA1 pyramidal neuron reconstruction through a pruning algorithm, measured all functional maps in each pruned reconstruction, and arrived at functional forms for the dependence of underlying measurements on dendritic length. We found that, across frequencies, atrophied neurons responded with higher efficiency to incoming inputs, and the transfer of signals across the dendritic tree was more effective in an atrophied reconstruction. Importantly, despite the presence of identical HCN-channel density gradients, spatial gradients in input resistance, local/transfer resonance frequencies and impedance profiles were significantly constricted in reconstructions with dendritic atrophy, where these physiological measurements across dendritic locations converged to similar values. These results revealed that, in atrophied dendritic structures, the presence of an ion channel density gradient alone was insufficient to sustain homologous functional maps along the same neuronal topograph. We assessed the biophysical basis for these conclusions and found that this atrophy-induced constriction of functional maps was mediated by an enhanced spatial spread of the influence of an HCN-channel cluster in atrophied trees. These results demonstrated that the influence fields of ion channel conductances need to be localized for channel gradients to express themselves as homologous functional maps, suggesting that ion channel gradients are necessary but not sufficient for the emergence of functional maps within single neurons

  4. Dietary niche constriction when invaders meet natives: evidence from freshwater decapods.

    PubMed

    Jackson, Michelle C; Grey, Jonathan; Miller, Katie; Britton, J Robert; Donohue, Ian

    2016-07-01

    Invasive species are a key driver of global environmental change, with frequently strong negative consequences for native biodiversity and ecosystem processes. Understanding competitive interactions between invaders and functionally similar native species provides an important benchmark for predicting the consequences of invasion. However, even though having a broad dietary niche is widely considered a key factor determining invasion success, little is known about the effects of competition with functionally similar native competitors on the dietary niche breadths of invasive species. We used a combination of field experiments and field surveys to examine the impacts of competition with a functionally similar native crab species on the population densities, growth rates and diet of the globally widespread invasive red swamp crayfish in an African river ecosystem. The presence of native crabs triggered significant dietary niche constriction within the invasive crayfish population. Further, growth rates of both species were reduced significantly, and by a similar extent, in the presence of one another. In spite of this, crayfish maintained positive growth rates in the presence of crabs, whereas crabs lost mass in the presence of crayfish. Consequently, over the 3-year duration of the study, crab abundance declined at those sites invaded by the crayfish, becoming locally extinct at one. The invasive crayfish had a dramatic effect on ecosystem structure and functioning, halving benthic invertebrate densities and increasing decomposition rates fourfold compared to the crabs. This indicates that replacement of native crabs by invasive crayfish likely alters the structure and functioning of African river ecosystems significantly. This study provides a novel example of the constriction of the dietary niche of a successful invasive population in the presence of competition from a functionally similar native species. This finding highlights the importance of considering both

  5. Gas-bubble snap-off under pressure driven flow in constricted noncircular capillaries

    SciTech Connect

    Kovscek, A.R.; Radke, C.J.

    1996-04-01

    A model for snap-off of a gas thread in a constricted cornered pore is developed. The time for wetting liquid to accumulate at a pore throat into an unstable collar is examined, as for the resulting pore-spanning lens to be displaced from the pore so that snap-off is the time may repeat. A comer-flow hydrodynamic analysis for the accumulation rate of wetting liquid due to both gradients in interfacial curvature and in applied liquid-phase pressure reveals that wetting-phase pressure gradients significantly increase the frequency of liquid accumulation for snap-off as compared to liquid rearrangement driven only by differences in pore-wall curvature. For moderate and large pressure gradients, the frequency of accumulation increases linearly with pressure gradient because of the increased rate of wetting liquid flow along pore comers. Pore topology is important to the theory, for pores with relatively small throats connected to large bodies demonstrate excellent ability to snapoff gas threads even when the initial capillary pressure is high or equivalently when the liquid saturation is low. A macroscopic momentum balance across the lens resulting from snap-off reveals that lens displacement rates are not linear with the imposed pressure drop. Instead, the frequency of lens displacement scales with powers between 0.5 and 0.6 for pores with dimensionless constriction radii between 0.15 and 0.40. Statistical percolation arguments are employed to form a generation rate expression and connect pore-level foam generation events to macroscopic pressure gradients in porous media. The rate of foam generation by capillary snap-off increases linearly with the liquid-phase pressure gradient and according to a power-law relationship with respect to the imposed gas-phase pressure gradient.

  6. Prefission Constriction of Golgi Tubular Carriers Driven by Local Lipid Metabolism: A Theoretical Model

    PubMed Central

    Shemesh, Tom; Luini, Alberto; Malhotra, Vivek; Burger, Koert N. J.; Kozlov, Michael M.

    2003-01-01

    Membrane transport within mammalian cells is mediated by small vesicular as well as large pleiomorphic transport carriers (TCs). A major step in the formation of TCs is the creation and subsequent narrowing of a membrane neck connecting the emerging carrier with the initial membrane. In the case of small vesicular TCs, neck formation may be directly induced by the coat proteins that cover the emerging vesicle. However, the mechanism underlying the creation and narrowing of a membrane neck in the generation of large TCs remains unknown. We present a theoretical model for neck formation based on the elastic model of membranes. Our calculations suggest a lipid-driven mechanism with a central role for diacylglycerol (DAG). The model is applied to a well-characterized in vitro system that reconstitutes TC formation from the Golgi complex, namely the pearling and fission of Golgi tubules induced by CtBP/BARS, a protein that catalyzes the conversion of lysophosphatidic acid into phosphatidic acid. In view of the importance of a PA-DAG cycle in the formation of Golgi TCs, we assume that the newly formed phosphatidic acid undergoes rapid dephosphorylation into DAG. DAG possesses a unique molecular shape characterized by an extremely large negative spontaneous curvature, and it redistributes rapidly between the membrane monolayers and along the membrane surface. Coupling between local membrane curvature and local lipid composition results, by mutual enhancement, in constrictions of the tubule into membrane necks, and a related inhomogeneous lateral partitioning of DAG. Our theoretical model predicts the exact dimensions of the constrictions observed in the pearling Golgi tubules. Moreover, the model is able to explain membrane neck formation by physiologically relevant mole fractions of DAG. PMID:14645071

  7. Role of cardiac output and the autonomic nervous system in the antinatriuretic response to acute constriction of the thoracic superior vena cava.

    NASA Technical Reports Server (NTRS)

    Schrier, R. W.; Humphreys, M. H.; Ufferman, R. C.

    1971-01-01

    Study of the differential characteristics of hepatic congestion and decreased cardiac output in terms of potential afferent stimuli in the antinatriuretic effect of acute thoracic inferior vena cava (TIVC) constriction. An attempt is made to see if the autonomic nervous system is involved in the antinatriuretic effect of acute TIVC or thoracic superior vena cava constriction.

  8. Radioactive gold ring dermatitis

    SciTech Connect

    Miller, R.A.; Aldrich, J.E. )

    1990-08-01

    A superficial squamous cell carcinoma developed in a woman who wore a radioactive gold ring for more than 30 years. Only part of the ring was radioactive. Radiation dose measurements indicated that the dose to basal skin layer was 2.4 Gy (240 rad) per week. If it is assumed that the woman continually wore her wedding ring for 37 years since purchase, she would have received a maximum dose of approximately 4600 Gy.

  9. Talk to Your Doctor about Abdominal Aortic Aneurysm

    MedlinePlus

    ... español Talk to Your Doctor about Abdominal Aortic Aneurysm Browse Sections The Basics Overview What is AAA? ... doctor about getting screened (tested) for abdominal aortic aneurysm (AAA). If AAA isn't found and treated ...

  10. Genetics Home Reference: familial thoracic aortic aneurysm and dissection

    MedlinePlus

    ... Home Health Conditions familial TAAD familial thoracic aortic aneurysm and dissection Enable Javascript to view the expand/ ... Open All Close All Description Familial thoracic aortic aneurysm and dissection ( familial TAAD ) involves problems with the ...

  11. Ventricular tachycardia following trans-apical aortic valve replacement.

    PubMed

    Beinart, Roy; Danik, Stephan; Palacios, Igor; Barrett, Conor; Inglessis, Ignacio; Agnihotri, Arvind; Passeri, Jonathan

    2012-03-01

    Transcatheter aortic valve replacement (TAVR) is a relatively new procedure for high-risk patients with severe aortic stenosis. We report a case of a new left ventricular outflow tract ventricular tachycardia following TAVR. PMID:22016303

  12. Neonatal magnetic resonance imaging in double aortic arch diagnosed prenatally by ultrasound.

    PubMed

    Trobo Marina, Duna; Bravo, Coral; Lancharro, Ángel; Gámez Alderete, Francisco; Marín, Carlos; de León-Luis, Juan

    2016-05-01

    Congenital double aortic arch (DAA) is an uncommon vascular anomaly; however, its prenatal detection is associated with congenital heart defects and chromosomal abnormalities, including 22q11 deletion. We present a case of DAA diagnosed prenatally. DAA can be diagnosed by prenatal ultrasound in the transverse three vessel-trachea view, which shows a trident image formed by a complete vascular ring and the ductus arteriosus. Postnatal magnetic resonance images in this view correlate well with prenatal ultrasound images and help in confirmation of diagnosis, evaluation of the risk of airway or esophageal compression, and planning of surgery. PMID:26979672

  13. Repair of right aortic arch with aberrant left subclavian artery and left ligamentum arteriosum.

    PubMed

    Chen, C L

    1990-07-01

    A case of right aortic arch with an aberrant left subclavian artery arising from a Kommerell's diverticulum of the descending thoracic aorta with a left ligamentum arteriosum completing a vascular ring about the trachea and esophagus is presented. A posterolateral left thoracotomy alone is sufficient to provide an excellent exposure for the division of the ligamentum arteriosum and the resection of the Kommerell's diverticulum. Furthermore, the development of a subclavian steal syndrome is prevented by the reimplantation of the divided left subclavian artery into the left common carotid artery through this same incision.

  14. Temperatures of Saturn's rings.

    NASA Technical Reports Server (NTRS)

    Murphy, R. E.

    1973-01-01

    The 20-micron brightness temperatures of the rings were determined using the 224-cm telescope of the Mauna Kea Observatory, and the standard University of Hawaii radiometer with a 17- to 25-micron filter. The observations were made on the nights of Aug. 20 and 21, and Sept. 26 and 27, 1972. The brightness temperatures of the A, B, and C rings are, respectively, 89 plus or minus 3 K, 94 plus or minus 2 K, and 89 plus or minus 4 K. A possible explanation of the relatively high temperature of the C ring is that Saturn has radiation belts and the inner ring is heated by particle bombardment.

  15. Real-time observation of aortic vessel dilation through delivery of sodium nitroprusside via slow release mesoporous nanoparticles.

    PubMed

    Farooq, Asima; Tosheva, Lubomira; Azzawi, May; Whitehead, Debra

    2016-09-15

    Spherical mesoporous nanoparticles (MNPs) with a diameter of ∼100nm were synthesised via a sol-gel method in the presences of organic template (with and without fluorescein dye encapsulation). The template molecules were removed by acidic extraction to form a regular pore lattice structure. The nanoparticle size and morphology were analysed using transmission electron microscopy and dynamic light scattering analysis. The MNPs were further characterised by zeta potential, nitrogen adsorption measurements and infra-red spectroscopy. The interior pores had an average diameter of ∼3nm and were loaded with an endothelial-independent vasodilator, sodium nitroprusside (SNP). The optimal drug loading and drug release was determined in high potassium physiological salt solution using dialysis and atomic absorption spectroscopy. We demonstrate that the initial instantaneous release is due to the surface desorption of the drug followed by diffusion from the pores. Furthermore, these drug loaded MNPs (with and without fluorescein dye encapsulation) were added to viable aortic vessels and release in real-time was observed, ex vivo. MNPs and loaded with and without SNP were incubated with the vessel (at 1.96×10(12)NPmL(-1)) over a 3h time period. The real-time exposure to unloaded MNPs resulted in a small attenuation in constriction that occurred after approximately 1h. In contrast, MNPs loaded with SNP led to a rapid relaxation of aortic vessels that was sustained over the 3h period (p<0.001). PMID:27288578

  16. Relationship between Shyness in Children and Constricted Cognitive Control as Measured by the Stroop Color-Word Test.

    ERIC Educational Resources Information Center

    Ludwig, Robert P.; Lazarus, Philip J.

    1983-01-01

    Investigated the relationship of shyness in children (N=103) to the constricted flexible dimension of cognitive control. Findings showed a significant difference in performance of the shy and nonshy group on the Stroop Color-Word Test. The shy group was less effective in maintaining performance in the presence of interfering stimuli. (JAC)

  17. Reconstruction of Moderately Constricted Ears by Combining V-Y Advancement of Helical Root, Conchal Cartilage Graft, and Mastoid Hitch

    PubMed Central

    Lashin, Riham

    2016-01-01

    Objective: Despite the multitude of corrective procedures described in the literature, adequate surgical correction of the congenital constricted ear remains a challenge. The maintenance of the shape and size of the reconstructed upper neohelix poses a particular problem. Methods: In the present study, a total of 12 cases of reconstruction were undertaken. All of them were moderate (type IIA Tanzer classification) deformities. A combined procedure was adopted using a V-Y advancement of the helical root, cartilage scoring, and cartilage grafting from the contralateral concha to reconstruct the upper helix. A mastoid hitch was used as an adjunct to these procedures to maintain helical elevation and prevent recurrence. Mean follow-up period was 6 months. Results: Results were excellent (n = 7), good (n = 4), and fair (n = 1). Paired t test showed a significant increase in the height of the constricted ear postoperatively (P < .001) and a nonsignificant difference between the height of the constricted and contralateral ears postoperatively (P > .05). Apart from dislodgment of the mastoid hitch suture in 1 patient, no complications were recorded. Conclusion: This combined technique is useful in correcting moderately constricted ear deformities. PMID:27468330

  18. Thoracic Endovascular Stent Graft Repair of Middle Aortic Syndrome.

    PubMed

    Kim, Joung Taek; Lee, Mina; Kim, Young Sam; Yoon, Yong Han; Baek, Wan Ki

    2016-09-01

    Middle aortic syndrome is a rare disease defined as a segmental narrowing of the distal descending thoracic or abdominal aorta. A thoracoabdominal bypass or endovascular treatment is the choice of treatment. Endovascular therapy consists of a balloon dilatation and stent implantation. Recently, thoracic endovascular aortic repair has been widely used in a variety of aortic diseases. We report a case of middle aortic syndrome treated with a thoracic endovascular stent graft. PMID:27549552

  19. Real-time transesophageal echocardiography facilitates antegrade balloon aortic valvuloplasty

    PubMed Central

    Ito, Kazato; Yano, Kentaro; Tanaka, Chiharu; Nakashoji, Tomohiro; Tonomura, Daisuke; Takehara, Kosuke; Kino, Naoto; Yoshida, Masataka; Kurotobi, Toshiya; Tsuchida, Takao; Fukumoto, Hitoshi

    2016-01-01

    We report two cases of severe aortic stenosis (AS) where antegrade balloon aortic valvuloplasty (BAV) was performed under real-time transesophageal echocardiography (TEE) guidance. Real-time TEE can provide useful information for evaluating the aortic valve response to valvuloplasty during the procedure. It was led with the intentional wire-bias technique in order to compress the severely calcified leaflet, and consequently allowed the balloon to reach the largest possible size and achieve full expansion of the aortic annulus. PMID:27054107

  20. Rapid prototyping in aortic surgery.

    PubMed

    Bangeas, Petros; Voulalas, Grigorios; Ktenidis, Kiriakos

    2016-04-01

    3D printing provides the sequential addition of material layers and, thus, the opportunity to print parts and components made of different materials with variable mechanical and physical properties. It helps us create 3D anatomical models for the better planning of surgical procedures when needed, since it can reveal any complex anatomical feature. Images of abdominal aortic aneurysms received by computed tomographic angiography were converted into 3D images using a Google SketchUp free software and saved in stereolithography format. Using a 3D printer (Makerbot), a model made of polylactic acid material (thermoplastic filament) was printed. A 3D model of an abdominal aorta aneurysm was created in 138 min, while the model was a precise copy of the aorta visualized in the computed tomographic images. The total cost (including the initial cost of the printer) reached 1303.00 euros. 3D imaging and modelling using different materials can be very useful in cases when anatomical difficulties are recognized through the computed tomographic images and a tactile approach is demanded preoperatively. In this way, major complications during abdominal aorta aneurysm management can be predicted and prevented. Furthermore, the model can be used as a mould; the development of new, more biocompatible, less antigenic and individualized can become a challenge in the future. PMID:26803324

  1. Endovascular repair of abdominal aortic aneurysms.

    PubMed

    Arnaoutakis, Dean J; Zammert, Martin; Karthikesalingam, Alan; Belkin, Michael

    2016-09-01

    Endovascular repair of abdominal aortic aneurysms is an important technique in the vascular surgeon's armamentarium, which has created a seismic shift in the management of aortic pathology over the past two decades. In comparison to traditional open repair, the endovascular approach is associated with significantly improved perioperative morbidity and mortality. The early survival benefit of endovascular abdominal aortic aneurysm repair is sustained up to 3 years postoperatively, but longer-term life expectancy remains poor regardless of operative modality. Nonetheless, most abdominal aortic aneurysms are now repaired using endovascular stent grafts. The technology is not perfect as several postoperative complications, namely endoleak, stent-graft migration, and graft limb thrombosis, can develop and therefore lifelong imaging surveillance is required. In addition, a postoperative inflammatory response has been documented after endovascular repair of aortic aneurysms; the clinical significance of this finding has yet to be determined. Subsequently, the safety and applicability of endovascular stent grafts are likely to improve and expand with the introduction of newer-generation devices and with the simplification of fenestrated systems. PMID:27650343

  2. Primary Stenting in Infrarenal Aortic Occlusive Disease

    SciTech Connect

    Nyman, Ulf; Uher, Petr; Lindh, Mats; Lindblad, Bengt; Ivancev, Krasnodar

    2000-03-15

    Purpose: To evaluate the results of primary stenting in aortic occlusive disease.Methods: Thirty patients underwent primary stenting of focal concentric (n = 2) and complex aortic stenoses (n = 19), and aortic or aorto-iliac occlusions (n = 9). Sixteen patients underwent endovascular outflow procedures, three of whom also had distal open surgical reconstructions. Median follow-up was 16 months (range 1-60 months).Results: Guidewire crossing of two aorto-biiliac occlusions failed, resulting in a 93% (28/30) technical success. Major complications included one access hematoma, one myocardial infarction, one death (recurrent thromboembolism) in a patient with widespread malignancy, and one fatal hemorrhage during thrombolysis of distal emboli from a recanalized occluded iliac artery. One patient did not improve his symptoms, resulting in a 1-month clinical success of 83% (25/30). Following restenting the 26 stented survivors changed their clinical limb status to +3 (n = 17) and +2 (n = 9). During follow-up one symptomatic aortic restenosis occurred and was successfully restented.Conclusions: Primary stenting of complex aortic stenoses and short occlusions is an attractive alternative to conventional surgery. Larger studies with longer follow-up and stratification of lesion morphology are warranted to define its role relative to balloon angioplasty. Stenting of aorto-biiliac occlusions is feasible but its role relative to bypass grafting remains to be defined.

  3. Echocardiographic assessment of severity of aortic regurgitation.

    PubMed Central

    Gray, K E; Barritt, D W

    1975-01-01

    An echocardiographic study of left ventricular diameter was made in 27 patients with aortic regurgitation. Comparison was made with a group of 21 normal subjects and a group of 6 patients with large left ventricles without valvar regurgitation. Total stroke volume, total left ventricular output, and ejection fraction were derived by the method of cubing the left ventricular diameter to give approximate left ventricular volumes at and-diastole and end-systole. The patients were assessed independently and placed into three grades of severity. The eechocardiographic dimensions of patients with mild aortic regurgitation were not significantly different from those of the normal subjects. With increasing severity of aortic regurgitation, there were increases in group values for left ventricular diameter, total stroke volume, and total left ventricular output. The ejection fraction was depressed below the normal range in only one patient with aortic regurgitation. It is concluded that echocardiographic measurement of left ventribular dimensions is of value in assessing the severity of aortic regurgitation. Images PMID:1156476

  4. Advances in Transcatheter Aortic Valve Replacement

    PubMed Central

    Kleiman, Neal S.; Reardon, Michael J.

    2016-01-01

    Transcatheter aortic valve replacement (TAVR) is becoming widely used for the treatment of symptomatic severe aortic stenosis in patients with high surgical risk. Data from The PARTNER Trial (Placement of AoRtic TraNscathetER Valves) and the Medtronic CoreValve® U.S. Pivotal Investigational Device Exemption trial indicate that survival for extreme-risk patients is superior to best medical therapy and equivalent or superior to surgical aortic valve replacement (SAVR), although long-term durability remains unknown. Paravalvular leak remains higher in TAVR than SAVR, as does permanent pacemaker implantation in self-expanding valves. New-generation valves are addressing these issues, especially for paravalvular leak. There is strong evidence that TAVR is appropriate for both extreme-risk and high-risk patients with symptomatic severe aortic stenosis, and the continued development of new valves are making implantation more reliable. This review discusses the studies supporting the use of TAVR and explores current advances in the field. PMID:27127560

  5. Gene Expression in Experimental Aortic Coarctation and Repair: Candidate Genes for Therapeutic Intervention?

    PubMed Central

    LaDisa, John F.; Bozdag, Serdar; Olson, Jessica; Ramchandran, Ramani; Kersten, Judy R.; Eddinger, Thomas J.

    2015-01-01

    Coarctation of the aorta (CoA) is a constriction of the proximal descending thoracic aorta and is one of the most common congenital cardiovascular defects. Treatments for CoA improve life expectancy, but morbidity persists, particularly due to the development of chronic hypertension (HTN). Identifying the mechanisms of morbidity is difficult in humans due to confounding variables such as age at repair, follow-up duration, coarctation severity and concurrent anomalies. We previously developed an experimental model that replicates aortic pathology in humans with CoA without these confounding variables, and mimics correction at various times using dissolvable suture. Here we present the most comprehensive description of differentially expressed genes (DEGs) to date from the pathology of CoA, which were obtained using this model. Aortic samples (n=4/group) from the ascending aorta that experiences elevated blood pressure (BP) from induction of CoA, and restoration of normal BP after its correction, were analyzed by gene expression microarray, and enriched genes were converted to human orthologues. 51 DEGs with >6 fold-change (FC) were used to determine enriched Gene Ontology terms, altered pathways, and association with National Library of Medicine Medical Subject Headers (MeSH) IDs for HTN, cardiovascular disease (CVD) and CoA. The results generated 18 pathways, 4 of which (cell cycle, immune system, hemostasis and metabolism) were shared with MeSH ID’s for HTN and CVD, and individual genes were associated with the CoA MeSH ID. A thorough literature search further uncovered association with contractile, cytoskeletal and regulatory proteins related to excitation-contraction coupling and metabolism that may explain the structural and functional changes observed in our experimental model, and ultimately help to unravel the mechanisms responsible for persistent morbidity after treatment for CoA. PMID:26207811

  6. Ring Around a Galaxy

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Space Telescope Science Institute astronomers are giving the public chances to decide where to aim NASA's Hubble Space Telescope. Guided by 8,000 Internet voters, Hubble has already been used to take a close-up, multi-color picture of the most popular object from a list of candidates, the extraordinary 'polar-ring' galaxy NGC 4650A. Located about 130 million light-years away, NGC 4650A is one of only 100 known polar-ring galaxies. Their unusual disk-ring structure is not yet understood fully. One possibility is that polar rings are the remnants of colossal collisions between two galaxies sometime in the distant past, probably at least 1 billion years ago. What is left of one galaxy has become the rotating inner disk of old red stars in the center. Meanwhile, another smaller galaxy which ventured too close was probably severely damaged or destroyed. The bright bluish clumps, which are especially prominent in the outer parts of the ring, are regions containing luminous young stars, examples of stellar rebirth from the remnants of an ancient galactic disaster. The polar ring appears to be highly distorted. No regular spiral pattern stands out in the main part of the ring, and the presence of young stars below the main ring on one side and above on the other shows that the ring is warped and does not lie in one plane. Determining the typical ages of the stars in the polar ring is an initial goal of our Polar Ring Science Team that can provide a clue to the evolution of this unusual galaxy. The HST exposures were acquired by the Hubble Heritage Team, consisting of Keith Noll, Howard Bond, Carol Christian, Jayanne English, Lisa Frattare, Forrest Hamilton, Anne Kinney and Zolt Levay, and guest collaborators Jay Gallagher (University of Wisconsin-Madison), Lynn Matthews (National Radio Astronomy Observatory-Charlottesville), and Linda Sparke (University of Wisconsin-Madison).

  7. Endovascular repair of a type B aortic dissection with a right-sided aortic arch: case report

    PubMed Central

    2013-01-01

    Right-sided aortic arch is a rare anomaly, and aortic dissection involving a right-sided aortic arch is extremely rare. We report the case of a 65-year-old man with a right-sided aortic arch and a right descending aortic dissection and a stent-graft was accurately deployed without perioperative complications. There were no any complaints and complications after 18 months follow-up. The CTA demonstrated that the false lumen was largely thrombosed only with a mild type II endoleak and a mild descending aortic expansion. We feel that endovascular repair is feasible to patient of type B aortic dissection with a right-sided aortic arch. However, long-term clinical efficacy and safety have yet to be confirmed. PMID:23343010

  8. Late degeneration of transcatheter aortic valves: pathogenesis and management.

    PubMed

    Barbanti, Marco; Tamburino, Corrado

    2016-09-18

    There is a growing body of evidence demonstrating the durability of current transcatheter aortic valve implantation (TAVI) devices up to 5 years. However, it is well known that transcatheter aortic valves can degenerate in a manner similar to surgical bioprostheses. In this review we briefly discuss the modes of failure of trans-catheter aortic valves and their potential management. PMID:27640028

  9. Caveolin-1 prevents sustained angiotensin II-induced resistance artery constriction and obesity-induced high blood pressure

    PubMed Central

    Czikora, Istvan; Feher, Attila; Lucas, Rudolf; Fulton, David J. R.

    2014-01-01

    The type 1 angiotensin II (ANG II) receptor (AT1R) undergoes internalization following stimulation by ANG II. Internalization reduces cell surface AT1Rs, and it is required for AT1R resensitization. In this process AT1R may interact with caveolin-1 (Cav1), the main scaffolding protein of caveolae. We hypothesized that the interaction between Cav1 and AT1R delays AT1R resensitization and thereby prevents sustained ANG II-induced resistance artery (RA) constriction under normal conditions and in experimental obesity. In rat and mouse skeletal muscle RA (diameter: ∼90–120 μm) ANG II-induced constrictions were reduced upon repeated (30-min apart) administrations. Upon disruption of caveolae with methyl-β-cyclodextrin or in RA of Cav1 knockout mice, repeated ANG II applications resulted in essentially maintained constrictions. In vascular smooth muscle cells, AT1R interacted with Cav1, and the degree of cell surface interactions was reduced by long-term (15-min), but not short-term (2-min), exposure to ANG II. When Cav1 was silenced, the amount of membrane-associated AT1R was significantly reduced by a short-term ANG II exposure. Moreover, Cav1 knockout mice fed a high-fat diet exhibited augmented and sustained RA constriction to ANG II and had elevated systemic blood pressure, when compared with normal or high-fat fed wild-type mice. Thus, Cav1, through a direct interaction, delays internalization and subsequent resensitization of AT1R. We suggest that this mechanism prevents sustained ANG II-induced RA constriction and elevated systemic blood pressure in diet-induced obesity. PMID:25527780

  10. Single cell rheometry with a microfluidic constriction: Quantitative control of friction and fluid leaks between cell and channel walls.

    PubMed

    Preira, Pascal; Valignat, Marie-Pierre; Bico, José; Théodoly, Olivier

    2013-01-01

    We report how cell rheology measurements can be performed by monitoring the deformation of a cell in a microfluidic constriction, provided that friction and fluid leaks effects between the cell and the walls of the microchannels are correctly taken into account. Indeed, the mismatch between the rounded shapes of cells and the angular cross-section of standard microfluidic channels hampers efficient obstruction of the channel by an incoming cell. Moreover, friction forces between a cell and channels walls have never been characterized. Both effects impede a quantitative determination of forces experienced by cells in a constriction. Our study is based on a new microfluidic device composed of two successive constrictions, combined with optical interference microscopy measurements to characterize the contact zone between the cell and the walls of the channel. A cell squeezed in a first constriction obstructs most of the channel cross-section, which strongly limits leaks around cells. The rheological properties of the cell are subsequently probed during its entry in a second narrower constriction. The pressure force is determined from the pressure drop across the device, the cell velocity, and the width of the gutters formed between the cell and the corners of the channel. The additional friction force, which has never been analyzed for moving and constrained cells before, is found to involve both hydrodynamic lubrication and surface forces. This friction results in the existence of a threshold for moving the cells and leads to a non-linear behavior at low velocity. The friction force can nevertheless be assessed in the linear regime. Finally, an apparent viscosity of single cells can be estimated from a numerical prediction of the viscous dissipation induced by a small step in the channel. A preliminary application of our method yields an apparent loss modulus on the order of 100 Pa s for leukocytes THP-1 cells, in agreement with the literature data.

  11. The Cerrillos Uplift, the La Bajada Constriction, and Hydrogeologic Framework of the Santo Domingo Basin, Rio Grande Rift, New Mexico

    USGS Publications Warehouse

    Minor, Scott A.

    2006-01-01

    The geologic, geophysical, and hydrogeologic properties of the La Bajada constriction and Santo Domingo Basin, northern New Mexico, result from tectonic and volcanic processes of the late Tertiary and Quaternary Rio Grande rift. An integrated geologic and geophysical assessment in the La Bajada constriction allows development of a geologic framework that can provide input for regional ground-water flow models. These models then can provide better estimates of future water supplies in a region that largely subsists on aquifers in Rio Grande rift basins. The combination of surface geologic investigations (stratigraphic and structural studies; chapters A, B, C, and E), airborne geophysics (aeromagnetic and time-domain electromagnetic surveys; chapters D and F), ground geophysical measurements (gravity and magnetotelluric surveys; chapters D and F), and data from the few wells in the area (chapter G) provides new constraints on the hydrogeologic framework of this area. Summary results of our investigations are synthesized in chapter G. Through-going aquifers consisting of ancestral Rio Grande axial-river sand and gravel and of coarse western-piedmont gravel form the predominant ground-water pathways through the partly buried structural trough defining the La Bajada constriction between Espa?ola and Santo Domingo Basins. Thick, clay-rich Cretaceous marine shales of low hydraulic conductivity form a pervasive regional confining unit within the Cerrillos uplift on the southeast flank of the constriction. Numerous, dominantly north-northwest-striking, intrabasin faults that project part way across the La Bajada constriction create a matrix of laterally and vertically variable hydrogeologic compartments that locally partition and deflect ground-water flow parallel to faults.

  12. Single cell rheometry with a microfluidic constriction: Quantitative control of friction and fluid leaks between cell and channel walls

    PubMed Central

    Preira, Pascal; Valignat, Marie-Pierre; Bico, José; Théodoly, Olivier

    2013-01-01

    We report how cell rheology measurements can be performed by monitoring the deformation of a cell in a microfluidic constriction, provided that friction and fluid leaks effects between the cell and the walls of the microchannels are correctly taken into account. Indeed, the mismatch between the rounded shapes of cells and the angular cross-section of standard microfluidic channels hampers efficient obstruction of the channel by an incoming cell. Moreover, friction forces between a cell and channels walls have never been characterized. Both effects impede a quantitative determination of forces experienced by cells in a constriction. Our study is based on a new microfluidic device composed of two successive constrictions, combined with optical interference microscopy measurements to characterize the contact zone between the cell and the walls of the channel. A cell squeezed in a first constriction obstructs most of the channel cross-section, which strongly limits leaks around cells. The rheological properties of the cell are subsequently probed during its entry in a second narrower constriction. The pressure force is determined from the pressure drop across the device, the cell velocity, and the width of the gutters formed between the cell and the corners of the channel. The additional friction force, which has never been analyzed for moving and constrained cells before, is found to involve both hydrodynamic lubrication and surface forces. This friction results in the existence of a threshold for moving the cells and leads to a non-linear behavior at low velocity. The friction force can nevertheless be assessed in the linear regime. Finally, an apparent viscosity of single cells can be estimated from a numerical prediction of the viscous dissipation induced by a small step in the channel. A preliminary application of our method yields an apparent loss modulus on the order of 100 Pa s for leukocytes THP-1 cells, in agreement with the literature data. PMID:24404016

  13. Physical exercise, aortic blood pressure, and aortic wall elasticity and composition in rats.

    PubMed

    Niederhoffer, N; Kieffer, P; Desplanches, D; Lartaud-Idjouadiene, I; Sornay, M H; Atkinson, J

    2000-04-01

    With a training schedule (8 weeks' treadmill running at 30 m/min up a 10% incline 5 d/wk for 90 min/day), we investigated whether exercise modifies aortic wall dimensions, composition (calcium and elastin content), or stiffness in normotensive 6-month-old male Wistar WAG/Rij rats. Maximal oxygen uptake was measured in half of the rats (n=10 per group). Wall stiffness was evaluated in the other half (9 trained and 10 untrained) on the basis of changes in thoracoabdominal pressure pulse wave velocity and differences in amplitude between the peripheral and central aortic pressure signals. Experiments were performed in nonanesthetized, unrestrained rats and then after pithing. The impact of exercise on the oxidative capacity of the plantaris muscles was evaluated with the measurement of citrate synthase activity. Training increased maximal oxygen uptake by 34% and citrate synthase activity by 40%. Mean peripheral aortic pressure increased by 6% and 19% in trained rats, under awake and pithed conditions, whereas mean central aortic pressure increased by 16%, after pithing only. All indexes of aortic stiffness were similar in trained and control rats, as were aortic wall dimensions, composition, cardiac mass, and heart rate. In conclusion, physical exercise in young rats appears to have no effect on aortic stiffness. PMID:10775562

  14. Diagnosis and management of acute aortic syndromes: dissection, intramural hematoma, and penetrating aortic ulcer.

    PubMed

    Bonaca, Marc P; O'Gara, Patrick T

    2014-01-01

    Acute aortic syndromes constitute a spectrum of conditions characterized by disruptions in the integrity of the aortic wall that may lead to potentially catastrophic outcomes. They include classic aortic dissection, intramural hematoma, and penetrating aortic ulcer. Although imaging studies are sensitive and specific, timely diagnosis can be delayed because of variability in presenting symptoms and the relatively low frequency with which acute aortic syndromes are seen in the emergency setting. Traditional classification systems, such as the Stanford system, facilitate early treatment decision-making through recognition of the high risk of death and major complications associated with involvement of the ascending aorta (type A). These patients are treated surgically unless intractable and severe co-morbidities are present. Outcomes with dissections that do not involve the ascending aorta (type B) depend on the presence of acute complications (e.g., malperfusion, early aneurysm formation, leakage), the patency and size of the false lumen, and patient co-morbidities. Patients with uncomplicated type B dissections are initially treated medically. Endovascular techniques have emerged as an alternative to surgery for the management of complicated type B dissections when intervention is necessary. Patients with acute aortic syndromes require aggressive medical care, risk stratification for additional complications and targeted genetic assessment as well as careful long-term monitoring to assess for evolving complications. The optimal care of patients with acute aortic syndrome requires the cooperation of members of an experienced multidisciplinary team both in the acute and chronic setting.

  15. Modulation of Pb(II) caused aortal constriction by eugenol and carvacrol.

    PubMed

    Shabir, Hiba; Kundu, Swati; Basir, Seemi Farhat; Khan, Luqman A

    2014-10-01

    Exposure to lead is known to cause vasoconstriction, exact mechanism of which remains to be elucidated. In this study, we investigate contractile responses of rat aortal rings equilibrated with Pb(II) in organ bath system, explore pathways responsible for hypercontraction and examine two ameliorators of lead-induced hypercontraction. At 1 μmol L(-1) Pb(II), aortal rings showed an average increase of 50% in isometric contraction. Incubation of rings, unexposed to Pb(II), with 1 μmol L(-1) sodium nitroprusside (nitric oxide (NO) donor), 100 μmol L(-1) apocynin (reactive oxygen species (ROS) inhibitor), and 100 μmol L(-1) indomethacin (cyclooxygenase inhibitor) lead to decrease in phenylephrine-induced contraction by 31, 27, and 29%, respectively. This decrease of contraction for Pb(II)-exposed rings was 48, 53, and 38%, respectively, indicating that ROS- and NO-dependent components of contractions are significantly elevated in Pb(II)-induced hypercontraction. Cyclooxygenase-dependent contractile component did not show significant elevation. Eugenol and carvacrol are plant-derived phenols known to possess antioxidant activity and hence could act as possible ameliorators of hypercontraction. At saturating concentrations of 100 μmol L(-1), eugenol and carvacrol caused a decrease in contraction by 38 and 42% in unexposed rings and 46 and 50% in Pb(II)-exposed rings. Co-incubation of rings with eugenol/carvacrol and various inhibitors suggests that both these active principles exert their relaxant effect via quenching of ROS and stimulation of NO synthesis. To conclude, Pb(II) is shown to induce hypercontraction of aortal rings through elevation of ROS and depletion of NO. This hypercontraction is effectively mitigated by eugenol and carvacrol.

  16. Vasoactivity of the ventral aorta of the American eel (Anguilla rostrata), Atlantic hagfish ( Myxine glutinosa), and sea lamprey (Petromyzon marinus).

    PubMed

    Evans, D H; Harrie, A C

    2001-04-15

    To determine if vascular smooth muscle from teleost and agnathan fishes expresses receptors for signaling agents that are important in vascular tension in other vertebrates, we exposed rings of aortic vascular smooth muscle from the eel (Anguilla rostrata), the hagfish (Myxine glutinosa), and the lamprey (Petromyzon marinus) to a suite of putative agonists, including: acetylcholine, endothelin, nitric oxide, natriuretic peptides, and prostanoids. Acetylcholine constricted aortic rings from the eel, but had no effect on the rings from lamprey. On the other hand, endothelin constricted rings from all three species. Use of receptor-specific ET agonists demonstrated that only ET(A) receptors are expressed in the eel and lamprey aorta. The nitric oxide donor sodium nitroprusside or nitric oxide itself dilated rings from the eel, but both agonists constricted rings from the hagfish and NO produced a biphasic response (constriction followed by dilation) in the lamprey. Two natriuretic peptides, eel ANP and porcine CNP, produced marginally significant dilation in the eel aorta, human ANP dilated the hagfish rings, and pCNP and eANP dilated the lamprey rings. The prostanoids PGE(1) and PGE(2) both dilated the eel aortic rings, and PGE(1) and carbaprostacyclin (stable PGI(2) agonist) dilated the hagfish and lamprey rings. Our results suggest that receptors for a variety of vasoactive signaling agents are expressed in the aortic smooth muscle of the earliest vertebrates (lamprey and hagfish), as well as the more advanced teleosts (eel).

  17. Smoke Ring Physics

    ERIC Educational Resources Information Center

    Huggins, Elisha

    2011-01-01

    The behavior of smoke rings, tornados, and quantized vortex rings in superfluid helium has many features in common. These features can be described by the same mathematics we use when introducing Ampere's law in an introductory physics course. We discuss these common features. (Contains 7 figures.)

  18. Lower esophageal ring (Schatzki)

    MedlinePlus

    ... narrowed area to stretch the ring. Sometimes, a balloon is placed in the area and inflated, to help widen the ring. Outlook (Prognosis) Swallowing problems may return. You may need repeat treatment. When to Contact a Medical Professional Call your health care provider if you ...

  19. EBT ring physics

    SciTech Connect

    Uckan, N.A.

    1980-04-01

    This workshop attempted to evaluate the status of the current experimental and theoretical understanding of hot electron ring properties. The dominant physical processes that influence ring formation, scaling, and their optimal behavior are also studied. Separate abstracts were prepared for each of the 27 included papers. (MOW)

  20. Contactless Magnetic Slip Ring

    NASA Technical Reports Server (NTRS)

    Kumagai, Hiroyuki (Inventor); Deardon, Joe D. (Inventor)

    1997-01-01

    A contactless magnetic slip ring is disclosed having a primary coil and a secondary coil. The primary and secondary coils are preferably magnetically coupled together, in a highly reliable efficient manner, by a magnetic layered core. One of the secondary and primary coils is rotatable and the contactless magnetic slip ring provides a substantially constant output.

  1. Smoke Ring Physics

    NASA Astrophysics Data System (ADS)

    Huggins, Elisha

    2011-11-01

    The behavior of smoke rings, tornados, and quantized vortex rings in superfluid helium has many features in common. These features can be described by the same mathematics we use when introducing Ampère's law in an introductory physics course. We discuss these common features.

  2. Jupiter's Gossamer Rings Explained.

    NASA Astrophysics Data System (ADS)

    Hamilton, D. P.

    2003-05-01

    Over the past several years, Galileo measurements and groundbased imaging have drastically improved our knowledge of Jupiter's faint ring system. We now recognize that the ring consists of four components: a main ring 7000km wide, whose inner edge blossoms into a vertically-extended halo, and a pair of more tenuous Gossamer rings, one associated with each of the small moons Thebe and Amalthea. When viewed edge on, the Gossamer rings appear as diaphanous disks whose thicknesses agree with the vertical excursions of the inclined satellites from the equatorial plane. In addition, the brightness of each Gossamer ring drops off sharply outside the satellite orbits. These correlations allowed Burns etal (1999, Science, 284, 1146) to argue convincingly that the satellites act as sources of the dusty ring material. In addition, since most material is seen inside the orbits of the source satellites, an inwardly-acting dissipative force such as Poynting-Robertson drag is implicated. The most serious problem with this simple and elegant picture is that it is unable to explain the existence of a faint swath of material that extends half a jovian radius outward from Thebe. A key constraint is that this material has the same thickness as the rest of the Thebe ring. In this work, we identify the mechanism responsible for the outward extension: it is a shadow resonance, first investigated by Horanyi and Burns (1991, JGR, 96, 19283). When a dust grain enters Jupiter's shadow, photoelectric processes shut down and the grain's electric charge becomes more negative. The electromagnetic forces associated with the varying charge cause periodic oscillations in the orbital eccentricity and semimajor axis as the orbital pericenter precesses. This results in a ring which spreads both inward and outward of its source satellite while preserving its vertical thickness - just as is observed for the Thebe ring. Predictions of the model are: i) gaps of micron-sized material interior to Thebe and

  3. A review of vascular rings 1980-1992.

    PubMed

    Ledwith, M V; Duff, D F

    1994-01-01

    Over a period of 13 years 21 patients between the ages of three weeks and 13 years presenting to this centre had a vascular ring. A double aortic arch was present in 11 cases, a right aortic arch with a retroesophageal left subclavian artery in five cases, a right aortic arch with a normal left innominate artery, a Kommerell's diverticulum and a left ligamentum arteriosum encircling the trachea and oesophagus occurred in two cases and an aberrant left pulmonary artery arising from the right pulmonary artery occurred in three cases. The majority (19/21) presented with a history of chronic stridor, although other significant associated symptoms included: recurrent respiratory infection, wheeze, cyanotic episodes and difficulty or pain on swallowing. The barium swallow was the most useful method of investigation and was diagnostic in all of the 95% of cases in which it was performed. Nineteen patients underwent surgery uneventfully although stridor often remained a problem for some time following repair. Six patients (28%) had associated congenital heart disease. Three (14%) patients who did not have surgery died.

  4. Jupiter's Rings: Sharpest View

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The New Horizons spacecraft took the best images of Jupiter's charcoal-black rings as it approached and then looked back at Jupiter. The top image was taken on approach, showing three well-defined lanes of gravel- to boulder-sized material composing the bulk of the rings, as well as lesser amounts of material between the rings. New Horizons snapped the lower image after it had passed Jupiter on February 28, 2007, and looked back in a direction toward the sun. The image is sharply focused, though it appears fuzzy due to the cloud of dust-sized particles enveloping the rings. The dust is brightly illuminated in the same way the dust on a dirty windshield lights up when you drive toward a 'low' sun. The narrow rings are confined in their orbits by small 'shepherding' moons.

  5. Abdominal aortic aneurysmectomy in renal transplant patients.

    PubMed Central

    Lacombe, M

    1986-01-01

    Five patients who had undergone renal transplantation 3 months to 23 years ago were operated on successfully for an abdominal aortic aneurysm. In the first case, dating from 1973, the kidney was protected by general hypothermia. In the remaining patients, no measure was used to protect the kidney. Only one patient showed a moderate increase of blood creatinine in the postoperative period; renal function returned to normal in 15 days. All five patients have normal renal function 6 months to 11 years after aortic repair. Results obtained in this series show that protection of the transplant during aortic surgery is not necessary, provided adequate surgical technique is used. Such a technique is described in detail. Its use simplifies surgical treatment of such lesions and avoids the complex procedures employed in the seven previously published cases. Images FIGS. 1A and B. FIGS. 2A and B. FIGS. 3A and B. FIGS. 4A and B. FIGS. 5A and B. PMID:3510592

  6. Diagnosis and Management of Valvular Aortic Stenosis

    PubMed Central

    Czarny, Matthew J; Resar, Jon R

    2014-01-01

    Valvular aortic stenosis (AS) is a progressive disease that affects 2% of the population aged 65 years or older. The major cause of valvular AS in adults is calcification and fibrosis of a previously normal tricuspid valve or a congenital bicuspid valve, with rheumatic AS being rare in the United States. Once established, the rate of progression of valvular AS is quite variable and impossible to predict for any particular patient. Symptoms of AS are generally insidious at onset, though development of any of the three cardinal symptoms of angina, syncope, or heart failure portends a poor prognosis. Management of symptomatic AS remains primarily surgical, though transcatheter aortic valve replacement (TAVR) is becoming an accepted alternative to surgical aortic valve replacement (SAVR) for patients at high or prohibitive operative risk. PMID:25368539

  7. Aortic stiffness and distensibility among hypertensives.

    PubMed

    Meenakshisundaram, R; Kamaraj, K; Murugan, S; Thirumalaikolundusubramanian, P

    2009-09-01

    Hypertension is one among many factors that contribute to aortic stiffness, which has repercussions mainly on the heart. To assess aortic stiffness among essential hypertensives of South India and its relationship with gender. An analytical study was designed to assess aortic stiffness among 60 nonobese, nonalcoholic, nonsmoking, and non-caffeine consuming essential hypertensives without any overt illness or infection, and compared with 30 healthy age- and sex-matched nonhypertensives. They were assessed clinically and also by laboratory means. Their left ventricular mass (LV) and left ventricular ejection fraction (LVEF) were measured using Transthoracic echocardiogram. Aortic systolic and diastolic diameters were measured by using M-mode echocardiography during consecutive beats and averaged for each case. Finally, aortic stiffness was calculated. The data were analyzed statistically. Hypertensives were divided into Group I, consisting of patients with hypertension at least for 5 years, who were not adherent to medication, and Group II, consisting of patients with hypertension of duration between 6 months and 1 year. There were 20 males and 10 females in each group. There was no significant difference between the hypertensive groups and a control, normotensive, group with regard to BMI or total cholesterol. The means of LV mass (in grams), systolic BP (in mmHg), diastolic BP (in mmHg), aortic systolic diameter (in mm), aortic diastolic diameter (in mm), aortic distensibility (in mm), and aortic stiffness found in Group I, Group II, and controls were 105.8 +/- 23.8, 101.5 +/- 21, and 84 +/- 9.8; 138 +/- 14.2, 153 +/- 17.1, and 120 +/- 8.3; 90.5 +/- 11.6, 101.7 +/- 17.1, and 76.5 +/- 5; 30.85 +/- 2.6, 28.7 +/- 2.6, and 27.7 +/- 2.4; 28.7 +/- 2.2, 25.8 +/- 2.5, and 24.2 +/- 2.5; 2.14 +/- 0.3, 2.84 +/- 0.5, and 3.5 +/- 0.6; and 1.31 +/- 0.09, 1.14 +/- 0.1, and 1.04 +/- 0.08, respectively. The differences between the hypertensive groups and the control group were

  8. ED 02-1 ACUTE AORTIC SYNDROME.

    PubMed

    Song, Jae-Kwan

    2016-09-01

    The successful clinical introduction of various non-invasive imaging modalities has contributed to the establishment of 'acute aortic syndrome', a relatively new clinical syndrome incorporating several disease entities with similar clinical features (at the time of clinical presentation). Aortic dissection (AD) with intimal flap and two aortic channels (true and false lumens) is the most important disease entity in acute aortic syndrome. Clinical characteristics of AD have been established, with standardized treatment strategies depending on the affected site of the aorta. For the past several decades, variant forms of classic AD, including aortic intramural hematoma (IMH) and incomplete dissection, have been increasingly diagnosed in routine clinical practice worldwide, and imaging findings characteristic of these variant forms have been established for their differential diagnosis. As imaging findings, rather than clinical features, are critical for the differential diagnosis of acute aortic syndrome, careful interpretation of imaging results is necessary for accurate diagnosis and better clinical decision-making, thus improving patient outcomes. IMH is probably the most important variant form of classic AD and has been the source of intense controversy regarding its pathogenesis and optimal treatment options. Clinical reports regarding outcomes of patients with IMH from different centers have shown conflicting results and risk stratification based on imaging findings remains a challenging clinical issue.Intimal tears can have a very wide spectrum. For example, a stellate or linear intimal tear can involve the exposure of the underlying aortic media or adventitial layers but without the progression and separation of the medial layers, resulting in extensive undermining of the intimal layers. This incomplete dissection, characterized by an intimal tear without an intimal flap or hematoma, was reported to be present in 9 of 181 (5%) consecutive patients with

  9. Mechanical versus biological aortic valve replacement strategies.

    PubMed

    Reineke, D; Gisler, F; Englberger, L; Carrel, T

    2016-01-01

    Aortic valve replacement (AVR) is the most frequently performed procedure in valve surgery. The controversy about the optimal choice of the prosthetic valve is as old as the technique itself. Currently there is no perfect valve substitute available. The main challenge is to choose between mechanical and biological prosthetic valves. Biological valves include pericardial (bovine, porcine or equine) and native porcine bioprostheses designed in stented, stentless and sutureless versions. Homografts and pulmonary autografts are reserved for special indications and will not be discussed in detail in this review. We will focus on the decision making between artificial biological and mechanical prostheses, respectively. The first part of this article reviews guideline recommendations concerning the choice of aortic prostheses in different clinical situations while the second part is focused on novel strategies in the treatment of patients with aortic valve pathology. PMID:26678683

  10. Temporary extracorporeal bypass modalities during aortic surgery.

    PubMed

    Bassin, Levi; Bell, David

    2016-09-01

    The key to aortic surgery is protection of the brain, heart, spinal cord, and viscera. For operations involving the aortic arch, the focus is on cerebral protection, while for pathology involving the descending thoracic aorta, the focus is on spinal protection. Optimal cerebral and spinal protection requires an extensive knowledge of the operative steps and an understanding of the cardiopulmonary bypass modalities that are possible. A bloodless field is required when operating on the aorta. As a result, periods of ischemia to the central nervous system and end-organ viscera are often unavoidable. The main techniques to mitigate ischemia include hypothermia and selective perfusion of the ischemic organ in question. This chapter will first briefly review bypass modalities and then describe how they can be used for various aortic scenarios. PMID:27650344

  11. Endovascular repair of thoracic aortic aneurysm

    PubMed Central

    Akin, Ibrahim; Kische, Stephan; Rehders, Tim C.; Nienaber, Christoph A.; Rauchhaus, Mathias

    2010-01-01

    A thoracic aortic aneurysm (TAA) is a potentially life-threatening condition with structural weakness of the aortic wall, which can progress to arterial dilatation and rupture. Today, both an increasing awareness of vascular disease and the access to tomographic imaging facilitate the diagnosis of TAA even in an asymptomatic stage. The risk of rupture for untreated aneurysms beyond a diameter of 5.6 cm ranges from 46% to 74% and the two-year mortality rate is greater than 70%, with most deaths resulting from rupture. Treatment options include surgical and non-surgical repair to prevent aneurysm enlargement and rupture. While most cases of ascending aortic involvement are subject to surgical repair (partially with valve-preserving techniques), aneurysm of the distal arch and descending thoracic aorta are amenable to emerging endovascular techniques as an alternative to classic open repair or to a hybrid approach (combining debranching surgery with stent grafting) in an attempt to improve outcomes. PMID:22419919

  12. STEEL TRUSS TENSION RING SUPPORTING DOME ROOF. TENSION RING COVERED ...

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

    STEEL TRUSS TENSION RING SUPPORTING DOME ROOF. TENSION RING COVERED BY ARCHITECTURAL FINISH. TENSION RING ROLLER SUPPORT AT COLUMN OBSCURED BY COLUMN COVERINGS. - Houston Astrodome, 8400 Kirby Drive, Houston, Harris County, TX

  13. Tunable strength saddle-point contacts impact on quantum rings transmission

    NASA Astrophysics Data System (ADS)

    González, J. J.; Diago-Cisneros, L.

    2016-09-01

    A particular subject of investigation is the role of several sadle-point contact (QPC) parameters on the scattering properties of an Aharonov-Bohm-Aharonov-Casher quantum ring (QR) under Rashba-type spin orbit interaction. We discuss the interplay of the conductance with the confinement strengths and height of the QPC, which yields new and tunable harmonic and non-harmonics patterns, while one manipulates these constriction parameters. This phenomenology may be of utility to implement a novel way to modulate spin interference effects in semiconducting QRs, providing an appealing test-platform for spintronics applications.

  14. Aortic Input Impedance during Nitroprusside Infusion

    PubMed Central

    Pepine, Carl J.; Nichols, W. W.; Curry, R. C.; Conti, C. Richard

    1979-01-01

    Beneficial effects of nitroprusside infusion in heart failure are purportedly a result of decreased afterload through “impedance” reduction. To study the effect of nitroprusside on vascular factors that determine the total load opposing left ventricular ejection, the total aortic input impedance spectrum was examined in 12 patients with heart failure (cardiac index <2.0 liters/min per m2 and left ventricular end diastolic pressure >20 mm Hg). This input impedance spectrum expresses both mean flow (resistance) and pulsatile flow (compliance and wave reflections) components of vascular load. Aortic root blood flow velocity and pressure were recorded continuously with a catheter-tip electromagnetic velocity probe in addition to left ventricular pressure. Small doses of nitroprusside (9-19 μg/min) altered the total aortic input impedance spectrum as significant (P < 0.05) reductions in both mean and pulsatile components were observed within 60-90 s. With these acute changes in vascular load, left ventricular end diastolic pressure declined (44%) and stroke volume increased (20%, both P < 0.05). Larger nitroprusside doses (20-38 μg/min) caused additional alteration in the aortic input impedance spectrum with further reduction in left ventricular end diastolic pressure and increase in stroke volume but no additional changes in the impedance spectrum or stroke volume occurred with 39-77 μg/min. Improved ventricular function persisted when aortic pressure was restored to control values with simultaneous phenylephrine infusion in three patients. These data indicate that nitroprusside acutely alters both the mean and pulsatile components of vascular load to effect improvement in ventricular function in patients with heart failure. The evidence presented suggests that it may be possible to reduce vascular load and improve ventricular function independent of aortic pressure reduction. PMID:457874

  15. Esophageal atresia associated with a rare vascular ring and esophageal duplication diverticulum: a case report and review of the literature.

    PubMed

    Escobar, Mauricio A; Welke, Karl F; Holland, Randall M; Caty, Michael G

    2012-10-01

    Esophageal atresia with tracheoesophageal fistula (EA-TEF) associated with a right aortic arch poses a dilemma to the pediatric surgeon, often necessitating an operative approach via a left thoracotomy. A right aortic arch may be associated with a vascular ring, and EA-TEF, too, has been reported in association with a vascular ring. Rarely, esophageal atresia is associated with a second esophageal anomaly, such as a so-called "esophageal lung." To our knowledge, there is no report of all three in one patient. We report the first case of a patient with associated EA-TEF, vascular ring (diverticulum of Kommerell), and esophageal lung. The literature is reviewed for these rare entities.

  16. Spinal ischemia following abdominal aortic surgery.

    PubMed

    Ferguson, L R; Bergan, J J; Conn, J; Yao, J S

    1975-03-01

    Serious spinal cord ischemia may follow infrarenal abdominal aortic surgery. Five cases are summarized and added to the 23 previously published cases in order to identify this syndrome, emphasize its importance, and draw attention to the possibility of spontaneous recovery which may occur. The multifactorial complex which comprises each patient's clinical picture clouds a precise and specific cause for paraplegia in these cases. However, neither hypotension, steal phenomena nor emboli are necessary for completion of the syndrome. The relevant spinal cord arterial anatomy indicates that the common anomalies which occur favor development of spinal cord ischemia in the arteriosclerotic population which requires aortic surgery. No means of prevention is possible at this time.

  17. Idiopathic thoracic aortic aneurysm at pediatric age.

    PubMed

    Marín-Manzano, E; González-de-Olano, D; Haurie-Girelli, J; Herráiz-Sarachaga, J I; Bermúdez-Cañete, R; Tamariz-Martel, A; Cuesta-Gimeno, C; Pérez-de-León, J

    2009-03-01

    A 6-year-old-boy presented with epigastric pain and vomiting over 1 year. Chest X-ray and esophagogastric transit showed a mediastinal mass. A chest computerized tomography angiogram demonstrated a descending thoracic aortic aneurysm. Analytical determinations carried out were all negative. The aneurysm was surgically repaired using a Dacron patch. The anatomopathological study described atherosclerotic lesions with calcifications, compatible with an atherosclerotic aneurysm wall. Aneurysms are uncommon in the pediatric population. Usually, no pathogenesis can be determined, and thus, such cases are grouped as idiopathic. Direct repair with or without patch is a therapeutic alternative in pediatric aneurysms and can allow the growth of the aortic circumference.

  18. Contemporary management of blunt aortic trauma.

    PubMed

    Dubose, J J; Azizzadeh, A; Estrera, A L; Safi, H J

    2015-10-01

    Blunt thoracic aortic injury (BTAI) remains a common cause of death following blunt mechanisms of trauma. Among patients who survive to reach hospital care, significant advances in diagnosis and treatment afford previously unattainable survival. The Society for Vascular Surgery (SVS) guidelines provide current best-evidence suggestions for treatment of BTAI. However, several key areas of controversy regarding optimal BTAI care remain. These include the refinement of selection criteria, timing for treatment and the need for long-term follow-up data. In addition, the advent of the Aortic Trauma Foundation (ATF) represents an important development in collaborative research in this field.

  19. [Vascular rings: airway obstruction in children. Case series].

    PubMed

    Zanetta, Adrián; Cuestas, Giselle; Rodríguez, Hugo; Tiscornia, Carlos

    2012-12-01

    In children, extrinsic compression of the trachea is usually due to vascular origin, and less frequently caused by tumors, heart diseases, cysts and abscesses. Vascular rings are congenital anomalies of the aortic arch and its branches that compress the trachea and/or esophagus to varying degrees. Although these congenital anomalies are not frequent, they constitute a major cause of respiratory distress in children. Thus, these anomalies should be included in the differential diagnosis of obstruction of the upper airway. Symptoms include stridor, respiratory distress and dysphagia of different intensity. The high degree of clinical suspicion is the most important factor for diagnosis, fail to do so can cause a significant delay between symptom onset and correct diagnosis. We present four patients with different types of vascular rings in order to describe clinical manifestations, diagnosis and treatment.

  20. [Vascular rings: airway obstruction in children. Case series].

    PubMed

    Zanetta, Adrián; Cuestas, Giselle; Rodríguez, Hugo; Tiscornia, Carlos

    2012-12-01

    In children, extrinsic compression of the trachea is usually due to vascular origin, and less frequently caused by tumors, heart diseases, cysts and abscesses. Vascular rings are congenital anomalies of the aortic arch and its branches that compress the trachea and/or esophagus to varying degrees. Although these congenital anomalies are not frequent, they constitute a major cause of respiratory distress in children. Thus, these anomalies should be included in the differential diagnosis of obstruction of the upper airway. Symptoms include stridor, respiratory distress and dysphagia of different intensity. The high degree of clinical suspicion is the most important factor for diagnosis, fail to do so can cause a significant delay between symptom onset and correct diagnosis. We present four patients with different types of vascular rings in order to describe clinical manifestations, diagnosis and treatment. PMID:23224313

  1. Genes and Abdominal Aortic Aneurysm

    PubMed Central

    Hinterseher, Irene; Tromp, Gerard; Kuivaniemi, Helena

    2010-01-01

    Abdominal aortic aneurysm (AAA) is a multifactorial disease with a strong genetic component. Since first candidate gene studies were published 20 years ago, nearly 100 genetic association studies using single nucleotide polymorphisms (SNPs) in biologically relevant genes have been reported on AAA. The studies investigated SNPs in genes of the extracellular matrix, the cardiovascular system, the immune system, and signaling pathways. Very few studies were large enough to draw firm conclusions and very few results could be replicated in another sample set. The more recent unbiased approaches are family-based DNA linkage studies and genome-wide genetic association studies, which have the potential of identifying the genetic basis for AAA, if appropriately powered and well-characterized large AAA cohorts are used. SNPs associated with AAA have already been identified in these large multicenter studies. One significant association was of a variant in a gene called CNTN3 which is located on chromosome 3p12.3. Two follow-up studies, however, could not replicate the association. Two other SNPs, which are located on chromosome 9p21 and 9q33 were replicated in other samples. The two genes with the strongest supporting evidence of contribution to the genetic risk for AAA are the CDKN2BAS gene, also known as ANRIL, which encodes an antisense RNA that regulates expression of the cyclin-dependent kinase inhibitors CDKN2A and CDKN2B, and DAB2IP, which encodes an inhibitor of cell growth and survival. Functional studies are now needed to establish the mechanisms by which these genes contribute to AAA pathogenesis. PMID:21146954

  2. Aortic injuries in newer vehicles.

    PubMed

    Ryb, Gabriel E; Dischinger, Patricia C; Kleinberger, Michael; McGwin, Gerald; Griffin, Russell L

    2013-10-01

    The occurrence of AI was studied in relation to vehicle model year (MY) among front seat vehicular occupants, age≥16 in vehicles MY≥1994, entered in the National Automotive Sampling System Crashworthiness Data System between 1997 and 2010 to determine whether newer vehicles, due to their crashworthiness improvements, are linked to a lower risk of aortic injuries (AI). MY was categorized as 1994-1997, 1998-2004, or 2005-2010 reflecting the introduction of newer occupant protection technology. Logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals for the association between AI and MY independent of possible confounders. Analysis was repeated, stratified by frontal and near lateral impacts. AI occurred in 19,187 (0.06%) of the 31,221,007 (weighted) cases, and contributed to 11% of all deaths. AIs were associated with advanced age, male gender, high BMI, near-side impact, rollover, ejection, collision against a fixed object, high ΔV, vehicle mismatch, unrestrained status, and forward track position. Among frontal crashes, MY 98-04 and MY 05-10 showed increased adjusted odds of AI when compared to MY 94-97 [OR 1.84 (1.02-3.32) and 1.99 (0.93-4.26), respectively]. In contrast, among near-side impact crashes, MY 98-04 and MY 05-10 showed decreased adjusted odds of AI [OR 0.50 (0.25-0.99) and 0.27 (0.06-1.31), respectively]. While occupants of newer vehicles experience lower odds of AI in near side impact crashes, a higher AI risk is present in frontal crashes. PMID:23831451

  3. EXPERIMENTAL MODELLING OF AORTIC ANEURYSMS

    PubMed Central

    Doyle, Barry J; Corbett, Timothy J; Cloonan, Aidan J; O’Donnell, Michael R; Walsh, Michael T; Vorp, David A; McGloughlin, Timothy M

    2009-01-01

    A range of silicone rubbers were created based on existing commercially available materials. These silicones were designed to be visually different from one another and have distinct material properties, in particular, ultimate tensile strengths and tear strengths. In total, eleven silicone rubbers were manufactured, with the materials designed to have a range of increasing tensile strengths from approximately 2-4MPa, and increasing tear strengths from approximately 0.45-0.7N/mm. The variations in silicones were detected using a standard colour analysis technique. Calibration curves were then created relating colour intensity to individual material properties. All eleven materials were characterised and a 1st order Ogden strain energy function applied. Material coefficients were determined and examined for effectiveness. Six idealised abdominal aortic aneurysm models were also created using the two base materials of the study, with a further model created using a new mixing technique to create a rubber model with randomly assigned material properties. These models were then examined using videoextensometry and compared to numerical results. Colour analysis revealed a statistically significant linear relationship (p<0.0009) with both tensile strength and tear strength, allowing material strength to be determined using a non-destructive experimental technique. The effectiveness of this technique was assessed by comparing predicted material properties to experimentally measured methods, with good agreement in the results. Videoextensometry and numerical modelling revealed minor percentage differences, with all results achieving significance (p<0.0009). This study has successfully designed and developed a range of silicone rubbers that have unique colour intensities and material strengths. Strengths can be readily determined using a non-destructive analysis technique with proven effectiveness. These silicones may further aid towards an improved understanding of the

  4. Pleural Empyema and Aortic Aneurysm

    PubMed Central

    Wu, Ching-Yang; Su, Ta-Wei; Huang, Kuo-Yang; Ko, Po-Jen; Yu, Sheng-Yueh; Kao, Tsung-Chi; Shen, Te-Chun; Chou, Tzu-Yi; Lin, Cheng-Li; Kao, Chia-Hung

    2015-01-01

    Abstract Pleural empyema (PE) may evolve into necrosis, fistula in the thorax, and sepsis; thus, it is also associated with high mortality. We investigated and analyzed the risk of aortic aneurysm (AA) in a cohort study of patients with PE. A total of 34,250 patients diagnosed with PE were identified as the PE cohort, and 137,000 patients without PE were selected randomly as the control group and matched by sex, age, and index year of PE diagnosis. Patients ages 20 years and younger with a history of AA were excluded. The risk of AA was analyzed using a Cox proportional hazards regression model. Excess risk of AA development was 1.69-fold higher in PE patients (adjusted hazard ratio [aHR] = 1.69; 95% confidence interval [CI] = 1.39–2.05) compared with non-PE patients. The patients with PE exhibited a greater adjusted risk of AA (aHR = 2.01; CI = 1.44–2.81) even if they did not have any of the 9 comorbidities included in our analysis (diabetes, hypertension, hyperlipidemia, chronic obstructive pulmonary disease, heart failure, cardiac artery disease, stroke, bacterial endocarditis, and rheumatic endocarditis). Compared with the patients without any of the 9 comorbidities or PE, the patients with only PE had a greater risk of developing AA (aHR = 2.00; CI = 1.43–2.79). The PE cohort had a significantly higher cumulative incidence of AA than the non-PE cohort did during 12 years of follow-up. In a large-scale cohort, patients with PE are linked with an increased risk of AA. PMID:26632741

  5. The Enceladus Ring

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] The Enceladus Ring (labeled)

    This excellent view of the faint E ring -- a ring feature now known to be created by Enceladus -- also shows two of Saturn's small moons that orbit within the ring, among a field of stars in the background.

    The E ring extends from three to eight Saturn radii -- about 180,000 kilometers (118,000 miles) to 482,000 kilometers (300,000 miles). Its full extent is not visible in this view.

    Calypso (22 kilometers, or 14 miles across) and Helene (32 kilometers, or 20 miles across) orbit within the E ring's expanse. Helene skirts the outer parts of the E ring, but here it is projected in front of a region deeper within the ring.

    Calypso and Helene are trojan satellites, or moons that orbit 60 degrees in front or behind a larger moon. Calypso is a Tethys trojan and Helene is a trojan of Dione.

    An interesting feature of note in this image is the double-banded appearance of the E-ring, which is created because the ring is somewhat fainter in the ringplane than it is 500-1,000 kilometers (300-600 miles) above and below the ringplane. This appearance implies that the particles in this part of the ring have nonzero inclinations (a similar affect is seen in Jupiter's gossamer ring). An object with a nonzero inclination does not orbit exactly at Saturn's ringplane. Instead, its orbit takes it above and below the ringplane. Scientists are not entirely sure why the particles should have such inclinations, but they are fairly certain that the reason involves Enceladus.

    One possible explanation is that all the E ring particles come from the plume of icy material that is shooting due south out of the moon's pole. This means all of the particles are created with a certain velocity out of the ringplane, and then they orbit above and below that plane.

    Another possible explanation is that Enceladus produces particles with a range of speeds, but the moon gravitationally

  6. Infected abdominal aortic aneurysm due to Morganella morganii: CT findings.

    PubMed

    Kwon, Oh Young; Lee, Jong Seok; Choi, Han Sung; Hong, Hoon Pyo; Ko, Young Gwan

    2011-02-01

    An infected aortic aneurysm, or mycotic aneurysm, is a rare arterial dilatation due to destruction of the infected vessel wall. Common pathogens resulting in an infected aortic aneurysm are Salmonella and Clostridium species, as well as Staphylococcus aureus; Morganella morganii, on the other hand, is very rare. An infected abdominal aortic aneurysm has tendencies to grow rapidly and to rupture. The mortality rate is high in patients undergoing emergent surgical intervention. We report the case of a 65-year-old man who presented with an infected abdominal aortic aneurysm caused by M. morganii. A high index of suspicion and imaging tests are necessary in order to diagnose an infected aortic aneurysm.

  7. Earth: A Ringed Planet?

    NASA Astrophysics Data System (ADS)

    Hancock, L. O.; Povenmire, H.

    2010-12-01

    Among the most beautiful findings of the Space Age have been the discoveries of planetary rings. Not only Saturn but also Jupiter, Uranus and Neptune have rings; Saturn’s ring system has structures newly discovered; even Saturn's moon Rhea itself has a ring. All these are apparently supplied by material from the planetary moons (Rhea's ring by Rhea itself). The question naturally arises, why should the Earth not have a ring, and on the other hand, if it does, why has it not been observed? No rings have yet been observed in the inner solar system, but after all, rings in the inner solar system might simply tend to be fainter and more transient than those of the outer solar system: the inner solar system is more affected by the solar wind, and the Sun’s perturbing gravitational influence is greater. J.A. O’Keefe first suggested (1980) that Earth might have a ring system of its own. An Earth ring could account for some climate events. O’Keefe remarked that formation or thickening of a ring system in Earth’s equatorial plane could drive glaciation by deepening the chill of the winter hemisphere. (It is very well established that volcanic dust is an effective agent for the extinction of sunlight; this factor can be overwhelmingly apparent in eclipse observations.) O’Keefe died in 2000 and the speculation was not pursued, but the idea of an Earth ring has a prima facie reasonableness that calls for its renewed consideration. The program of this note is to hypothesize that, as O’Keefe proposed: (a) an Earth ring system exists; (b) it affects Earth's weather and climate; (c) the tektite strewn fields comprise filaments of the ring fallen to Earth's surface on various occasions of disturbance by comets or asteroids. On this basis, and drawing on the world's weather records, together with the Twentieth Century Reanalysis by NCEP/CIRES covering the period 1870-2010 and the geology of the tektite strewn fields, we herein propose the hypothesized Earth ring

  8. Hot piston ring tests

    NASA Astrophysics Data System (ADS)

    Allen, David J.; Tomazic, William A.

    1987-12-01

    As part of the DOE/NASA Automotive Stirling Engine Project, tests were made at NASA Lewis Research Center to determine whether appendix gap losses could be reduced and Stirling engine performance increased by installing an additional piston ring near the top of each piston dome. An MTI-designed upgraded Mod I Automotive Stirling Engine was used. Unlike the conventional rings at the bottom of the piston, these hot rings operated in a high temperature environment (700 C). They were made of a high temperature alloy (Stellite 6B) and a high temperature solid lubricant coating (NASA Lewis-developed PS-200) was applied to the cylinder walls. Engine tests were run at 5, 10, and 15 MPa operating pressure over a range of operating speeds. Tests were run both with hot rings and without to provide a baseline for comparison. Minimum data to assess the potential of both the hot rings and high temperature low friction coating was obtained. Results indicated a slight increase in power and efficiency, an increase over and above the friction loss introduced by the hot rings. Seal leakage measurements showed a significant reduction. Wear on both rings and coating was low.

  9. Dynamics of narrow rings

    NASA Technical Reports Server (NTRS)

    Dermott, S. F.

    1984-01-01

    The ring models described here were developed to account for the dynamical problems posed by the narrow rings of Uranus. Some of these rings are now known to be eccentric, inclined, nonuniform in width, optically thick, and narrow, with very sharp edges. The eccentric rings have common pericenters and large, positive eccentricity gradients. The theory of shepherding satellites successfully accounts for most of these features and can also account for some features of the narrow Saturnian rings, in particular, waves, kinks, and periodic variations in brightness. Outstanding problems include the putative relation between eccentricity and inclination displayed by eight of the nine Uranian rings, and the magnitudes of the tidal torques acting on the shepherding satellites. The horseshoe-orbit model, although viable, probably has more application to the narrow rings from which the Saturnian coorbital satellites formed. The angular momentum flow rate due to particle collisions is a minimum at the Lagrangian equilibrium points L(4) and L(5), and one can expect accretion to be rapid at these points.

  10. Hot piston ring tests

    NASA Technical Reports Server (NTRS)

    Allen, David J.; Tomazic, William A.

    1987-01-01

    As part of the DOE/NASA Automotive Stirling Engine Project, tests were made at NASA Lewis Research Center to determine whether appendix gap losses could be reduced and Stirling engine performance increased by installing an additional piston ring near the top of each piston dome. An MTI-designed upgraded Mod I Automotive Stirling Engine was used. Unlike the conventional rings at the bottom of the piston, these hot rings operated in a high temperature environment (700 C). They were made of a high temperature alloy (Stellite 6B) and a high temperature solid lubricant coating (NASA Lewis-developed PS-200) was applied to the cylinder walls. Engine tests were run at 5, 10, and 15 MPa operating pressure over a range of operating speeds. Tests were run both with hot rings and without to provide a baseline for comparison. Minimum data to assess the potential of both the hot rings and high temperature low friction coating was obtained. Results indicated a slight increase in power and efficiency, an increase over and above the friction loss introduced by the hot rings. Seal leakage measurements showed a significant reduction. Wear on both rings and coating was low.

  11. Quantitative Assessment of Turbulence and Flow Eccentricity in an Aortic Coarctation: Impact of Virtual Interventions.

    PubMed

    Andersson, Magnus; Lantz, Jonas; Ebbers, Tino; Karlsson, Matts

    2015-09-01

    Turbulence and flow eccentricity can be measured by magnetic resonance imaging (MRI) and may play an important role in the pathogenesis of numerous cardiovascular diseases. In the present study, we propose quantitative techniques to assess turbulent kinetic energy (TKE) and flow eccentricity that could assist in the evaluation and treatment of stenotic severities. These hemodynamic parameters were studied in a pre-treated aortic coarctation (CoA) and after several virtual interventions using computational fluid dynamics (CFD), to demonstrate the effect of different dilatation options on the flow field. Patient-specific geometry and flow conditions were derived from MRI data. The unsteady pulsatile flow was resolved by large eddy simulation including non-Newtonian blood rheology. Results showed an inverse asymptotic relationship between the total amount of TKE and degree of dilatation of the stenosis, where turbulent flow proximal the constriction limits the possible improvement by treating the CoA alone. Spatiotemporal maps of TKE and flow eccentricity could be linked to the characteristics of the jet, where improved flow conditions were favored by an eccentric dilatation of the CoA. By including these flow markers into a combined MRI-CFD intervention framework, CoA therapy has not only the possibility to produce predictions via simulation, but can also be validated pre- and immediate post treatment, as well as during follow-up studies. PMID:26577361

  12. Persistent right aortic arch and aberrant left subclavian artery in a white Bengal tiger (Panthera tigris).

    PubMed

    Ketz, C J; Radlinsky, M; Armbrust, L; Carpenter, J W; Isaza, R

    2001-06-01

    A 3-mo-old male white Bengal tiger (Panthera tigris) presented with the chief complaint of regurgitation of solid food since weaning at 2 mo of age. Compared with its littermates, the tiger was in poor body condition and weighed only 10.3 kg when its littermates were estimated at 20-25 kg. Thoracic radiographs showed a megaesophagus cranial to the heart base. A contrast esophagram more clearly outlined the megaesophagus, and fluoroscopy demonstrated normal motility of the caudal esophagus. Endoscopic examination revealed a structure coursing dorsally from right to left over the esophagus and a constrictive band on the left of the esophagus at the heart base. Nonselective angiography confirmed the presence of a persistent right aortic arch, as well as an aberrant left subclavian artery. A left fourth intercostal thoracotomy was performed, and the ligamentum arteriosum was double ligated and divided. The left subclavian artery did not cause significant compromise of the esophagus and was not manipulated at surgery. The tiger recovered well from anesthesia and surgery. Solid food was slowly introduced over a 2-mo period without any regurgitation. The cub gained weight rapidly after surgery.

  13. Persistent right aortic arch and aberrant left subclavian artery in a white Bengal tiger (Panthera tigris).

    PubMed

    Ketz, C J; Radlinsky, M; Armbrust, L; Carpenter, J W; Isaza, R

    2001-06-01

    A 3-mo-old male white Bengal tiger (Panthera tigris) presented with the chief complaint of regurgitation of solid food since weaning at 2 mo of age. Compared with its littermates, the tiger was in poor body condition and weighed only 10.3 kg when its littermates were estimated at 20-25 kg. Thoracic radiographs showed a megaesophagus cranial to the heart base. A contrast esophagram more clearly outlined the megaesophagus, and fluoroscopy demonstrated normal motility of the caudal esophagus. Endoscopic examination revealed a structure coursing dorsally from right to left over the esophagus and a constrictive band on the left of the esophagus at the heart base. Nonselective angiography confirmed the presence of a persistent right aortic arch, as well as an aberrant left subclavian artery. A left fourth intercostal thoracotomy was performed, and the ligamentum arteriosum was double ligated and divided. The left subclavian artery did not cause significant compromise of the esophagus and was not manipulated at surgery. The tiger recovered well from anesthesia and surgery. Solid food was slowly introduced over a 2-mo period without any regurgitation. The cub gained weight rapidly after surgery. PMID:12790433

  14. The role of balloon aortic valvuloplasty in the era of transcatheter aortic valve implantation.

    PubMed

    Wacławski, Jacek; Wilczek, Krzysztof; Pres, Damian; Krajewski, Adam; Poloński, Lech; Zembala, Marian; Gąsior, Mariusz

    2015-03-01

    Balloon aortic valvuloplasty is recommended in patients not suitable for transcatheter aortic valve implantation/aortic valve replacement (TAVI/AVR) or when such interventions are temporarily contraindicated. The number of performed balloon aortic valvuloplasty (BAV) procedures has been increasing in recent years. Valvuloplasty enables the selection of individuals with severe left ventricular dysfunction or with symptoms of uncertain origin resulting from concomitant disorders (including chronic obstructive pulmonary disease [COPD]) who can benefit from destination therapy (AVR/TAVI). Thanks to improved equipment, the number of adverse effects is now lower than it was in the first years after the advent of BAV. Valvuloplasty can be safely performed even in unstable patients, but long-term results remain poor. In view of the limited availability of TAVI in Poland, it is reasonable to qualify patients for BAV more often, as it is a relatively safe procedure improving the clinical condition of patients awaiting AVR/TAVI. PMID:26336471

  15. Endovascular Management of Chronic Type B Dissecting Aortic Aneurysm Utilizing Aortic and Renal Stents

    SciTech Connect

    Taylor, J. D. Dunckley, M.; Thompson, M.; Morgan, R. A.

    2008-07-15

    Over the last 10 years endovascular stent-graft placement has been increasingly used to treat complicated acute Type B thoracic aortic dissections. While studies have demonstrated the use of additional aortic stent-grafts to treat continued false lumen perfusion and case reports have detailed the use of renal artery stents to treat renal ischemia related to aortic dissection, to our knowledge the adjuvant use of renal artery stents to reduce false lumen perfusion has not been reported. We present the case of a 72-year-old male who had previously undergone endovascular repair of a complicated Type B thoracic aortic dissection and presented with an expanding false lumen in the peridiaphragmatic aorta despite coverage of the entire thoracic aorta. This was treated by closure of a right renal fenestration using a renal stent.

  16. The Triplex BioValsalva Prostheses To Reconstruct the Aortic Valve and the Aortic Root.

    PubMed

    Fu, Yijun; Li, Bin; Bourget, Jean-Michel; Bondarenko, Olexandr; Lin, Jing; Guzman, Randolph; Paynter, Royston; Desaulniers, Denis; Qin, Boyin; Wang, Lu; Germain, Lucie; Zhang, Ze; Guidoin, Robert

    2016-01-01

    The Bentall procedure introduced in 1968 represents an undisputed cure to treat multiple pathologies involving the aortic valve and the ascending thoracic aorta. Over the years, multiple modifications have been introduced as well as a standardized approach to the operation with the goal to prevent long-term adverse events. The BioValsalva prosthesis provides a novel manner to more efficiently reconstruct the aortic valve together with the anatomy of the aortic root with the implantation of a valved conduit. This prosthesis comprises three sections: the collar supporting the valve; the skirt mimicking the Valsalva, which is suitable for the anastomoses with the coronary arteries; and the main body of the graft, which is designed to replace the ascending aorta. The BioValsalva prosthesis allows the Bentall operation to be used in patients whose aortic valve cannot be spared. PMID:27649763

  17. Aortic dilatation and aortopathy in congenital heart diseases.

    PubMed

    Zanjani, Keyhan Sayadpour; Niwa, Koichiro

    2013-01-01

    Longer survival after corrective surgery for congenital heart diseases has rendered late complications more important. One of these complications is aortic dilatation which may occur in patients with repaired or unrepaired disease and can progress to aneurysm, dissection, and rupture. This aortic dilatation in various congenital heart diseases does not simply mean anatomical dilatation of the aortic root, but it closely relates to the aortic pathophysiological abnormality, aortic regurgitation, and aortic and ventricular dysfunction; therefore, we can recognize this complex lesion as a new concept: "aortopathy". The pathophysiology of this disease is complex and only partially understood. In this review, we first discuss history, pathophysiology, and clinical features of aortic dilatation and aortopathy of congenital heart disease. Then we provide a review of the evaluation and management of this disease.

  18. Dynamics of the Uranian Rings

    NASA Technical Reports Server (NTRS)

    Dermott, S. F.

    1984-01-01

    Some of the problems of the shepherding satellite model of Goldreich ant tremaine are discussed. The following topics are studied: (1) optical depths of the all the observed narrow rings; (2) satellite and ring separation timescales; (3) ring edge sharpness; (4) shock formation in narrow rings; (5) the existence of small satellites near the Uranian rings; and (6) the apse and node alignments of the eccentric and inclined rings.

  19. Theodolite Ring Lights

    NASA Technical Reports Server (NTRS)

    Clark, David

    2006-01-01

    Theodolite ring lights have been invented to ease a difficulty encountered in the well-established optical-metrology practice of using highly reflective spherical tooling balls as position references. A theodolite ring light produces a more easily visible reflection and eliminates the need for an autocollimating device. A theodolite ring light is a very bright light source that is well centered on the optical axis of the instrument. It can be fabricated, easily and inexpensively, for use on a theodolite or telescope of any diameter.

  20. Alternative parallel ring protocols

    NASA Technical Reports Server (NTRS)

    Mukkamala, R.; Foudriat, E. C.; Maly, Kurt J.; Kale, V.

    1990-01-01

    Communication protocols are know to influence the utilization and performance of communication network. The effect of two token ring protocols on a gigabit network with multiple ring structure is investigated. In the first protocol, a mode sends at most one message on receiving a token. In the second protocol, a mode sends all the waiting messages when a token is received. The behavior of these protocols is shown to be highly dependent on the number of rings as well as the load in the network.