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Sample records for constriction ring syndrome

  1. Novel techniques for the surgical management of abdominopelvic constriction rings in amniotic band syndrome.

    PubMed

    Capone, Avery C; Balasundaram, Naveen; Caouette-Laberge, Louise; Papay, Frank A; Lucas, Armand R; Seifarth, Federico G; Doumit, Gaby D

    2015-02-01

    Constriction rings are associated with amniotic band syndrome and most often present in the extremities. Constriction bands of the trunk are rare, and a standard of surgical care remains elusive. Traditional methods of constriction ring excision rely on soft-tissue rearrangement with multiple Z-plasties, but renewed interest in linear closure and limited Z-plasty has emerged. The authors review contemporary literature and report two cases of abdominopelvic constriction ring reconstruction with long-term follow-up. Novel techniques including anterior sheath Y-V plasty, pteruges release of the Scarpa fascia, and limited Z-plasty closure may minimize the need for serrated scar patterns. PMID:25626800

  2. Acquired constriction ring syndrome as a cause of inconsolable cry in a child: a case report

    PubMed Central

    Singh, Vinay; Singh, Pankaj; Sharma, Amit; Sarkar, Jay

    2008-01-01

    Acute constriction ring syndrome (ACRS) is a rare clinical condition characterized by formation of a circumferential constriction ring around an appendage or genitalia. Cases are mostly reported in infants and young children. Early recognition and a definitive treatment are of paramount importance in order to avoid irreversible ischemia and possible auto-amputation. We describe a case of a 14-month-old child presented to casualty with a history of refusal to feed and inconsolable cry. Parents noticed a recent swelling of left third toe. On careful examination the child was found to have an acquired constriction ring secondary to a tightly wrapped hair around left third toe. An urgent surgical decompression was done by the orthopaedic team with complete resolution of symptoms. We summarized the pathophysiology of ACRS underlining the need of awareness in treating physicians. The possible medico legal implications should be kept in mind bearing a suggested link with non-accidental injury. PMID:18702819

  3. 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

  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. Protein Phosphatase 1ß Limits Ring Canal Constriction during Drosophila Germline Cyst Formation

    PubMed Central

    Yamamoto, Shinya; Bayat, Vafa; Bellen, Hugo J.; Tan, Change

    2013-01-01

    Germline cyst formation is essential for the propagation of many organisms including humans and flies. The cytoplasm of germline cyst cells communicate with each other directly via large intercellular bridges called ring canals. Ring canals are often derived from arrested contractile rings during incomplete cytokinesis. However how ring canal formation, maintenance and growth are regulated remains unclear. To better understand this process, we carried out an unbiased genetic screen in Drosophila melanogaster germ cells and identified multiple alleles of flapwing (flw), a conserved serine/threonine-specific protein phosphatase. Flw had previously been reported to be unnecessary for early D. melanogaster oogenesis using a hypomorphic allele. We found that loss of Flw leads to over-constricted nascent ring canals and subsequently tiny mature ring canals, through which cytoplasmic transfer from nurse cells to the oocyte is impaired, resulting in small, non-functional eggs. Flw is expressed in germ cells undergoing incomplete cytokinesis, completely colocalized with the Drosophila myosin binding subunit of myosin phosphatase (DMYPT). This colocalization, together with genetic interaction studies, suggests that Flw functions together with DMYPT to negatively regulate myosin activity during ring canal formation. The identification of two subunits of the tripartite myosin phosphatase as the first two main players required for ring canal constriction indicates that tight regulation of myosin activity is essential for germline cyst formation and reproduction in D. melanogaster and probably other species as well. PMID:23936219

  6. 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.

  7. 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.

  8. Plant cytokinesis-No ring, no constriction but centrifugal construction of the partitioning membrane.

    PubMed

    Müller, Sabine; Jürgens, Gerd

    2016-05-01

    Plants have evolved a unique way of partitioning the cytoplasm of dividing cells: Instead of forming a contractile ring that constricts the plasma membrane, plant cells target membrane vesicles to the plane of division where the vesicles fuse with one another to form the partitioning membrane. Plant cytokinesis starts in the centre and progresses towards the periphery, culminating in the fusion of the partitioning membrane with the parental plasma membrane. This membrane dynamics is orchestrated by a specific cytoskeletal array named phragmoplast that originates from interzone spindle remnants. Here we review the properties of the process as well as molecules that play specific roles in that process. PMID:26529278

  9. An acto-myosin II constricting ring initiates the fission of activity-dependent bulk endosomes in neurosecretory cells.

    PubMed

    Gormal, Rachel S; Nguyen, Tam H; Martin, Sally; Papadopulos, Andreas; Meunier, Frederic A

    2015-01-28

    Activity-dependent bulk endocytosis allows neurons to internalize large portions of the plasma membrane in response to stimulation. However, whether this critical type of compensatory endocytosis is unique to neurons or also occurs in other excitable cells is currently unknown. Here we used fluorescent 70 kDa dextran to demonstrate that secretagogue-induced bulk endocytosis also occurs in bovine chromaffin cells. The relatively large size of the bulk endosomes found in this model allowed us to investigate how the neck of the budding endosomes constricts to allow efficient recruitment of the fission machinery. Using time-lapse imaging of Lifeact-GFP-transfected chromaffin cells in combination with fluorescent 70 kDa dextran, we detected acto-myosin II rings surrounding dextran-positive budding endosomes. Importantly, these rings were transient and contracted before disappearing, suggesting that they might be involved in restricting the size of the budding endosome neck. Based on the complete recovery of dextran fluorescence after photobleaching, we demonstrated that the actin ring-associated budding endosomes were still connected with the extracellular fluid. In contrast, no such recovery was observed following the constriction and disappearance of the actin rings, suggesting that these structures were pinched-off endosomes. Finally, we showed that the rings were initiated by a circular array of phosphatidylinositol(4,5)bisphosphate microdomains, and that their constriction was sensitive to both myosin II and dynamin inhibition. The acto-myosin II rings therefore play a key role in constricting the neck of budding bulk endosomes before dynamin-dependent fission from the plasma membrane of neurosecretory cells. PMID:25632116

  10. 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

  11. Using a Distant Abdominal Skin Flap to Treat Digital Constriction Bands: A Case Report for Vohwinkel Syndrome.

    PubMed

    Zhang, Mingzi; Song, Kexin; Ding, Ning; Shu, Chang; Wang, Youbin

    2016-02-01

    In this study, a Vohwinkel syndrome case is presented where in 5th digit constriction bands in the right hand were reconstructed using a distant abdominal skin flap. Vohwinkel syndrome, or keratoderma hereditarium mutilans, is a rare, autosomal dominant genetic skin condition that causes palmoplantar hyperkeratosis and constricts finger and/or toe bands. In a typical manifestation, the finger and toe constriction bands lead to progressive strangulation and autoamputation, which requires immediate clinical treatment. Topical keratolytics and systemic retinoids have been used to treat hyperkeratosis but without consistent results. Only 1 effective approach for autoamputation has been accepted, reconstructive surgery.Applying a distant abdominal skin flap produced satisfying postoperative effects at the 18-month follow-up. PMID:26871826

  12. Flail extremity resulting from constriction band syndrome: Neurovascular implications and surgical management

    PubMed Central

    Rapp, Scott J.; Pan, Brian S.; Yakuboff, Kevin P.

    2014-01-01

    Abstract Purpose: Constriction band syndrome afflicting in utero development can lead to devastating and possibly fatal outcomes. A lack of consensus regarding noninvasive testing and surgical modalities is likely secondary to the continued poorly understood pathology. Methods: We provide a case report of a 6-month-old boy who presented with a functional, nonsensate upper limb after surgical release of midhumeral banding at 3 months of age. Results: Exploration revealed intact, albeit atrophic, peripheral nerves with brachial artery disruption above the elbow. Sural nerve grafting was performed and 2-year follow-up demonstrated return of protective sensation in the median nerve distribution with minimal motor return. Conclusion: This case demonstrates that nerves present distal to the original soft tissue insult oppose the idea of failure of nerve formation. Early nerve grafting at the time of initial Z-plasty release may serve to improve long-term functional outcomes.

  13. Phase-field modelling of the dynamics of Z-ring formation in liposomes: Onset of constriction and coarsening.

    PubMed

    Picallo, C B; Barrio, R A; Varea, C; Alarcón, T; Hernandez-Machado, A

    2015-06-01

    We propose a model for the dynamics of the formation of rings of FtsZ on tubular liposomes which produce constriction on the corresponding membrane. Our phase-field model is based on a simple bending energy that captures the dynamics of the interplay between the protein and the membrane. The short-time regime is analyzed by a linear dispersion relation, with which we are able to predict the number of rings per unit length on a tubular liposome. We study numerically the long-time dynamics of the system in the non-linear regime where we observe coarsening of Z-rings on tubular liposomes. In particular, our numerical results show that, during the coarsening process, the number of Z-rings decreases as the radius of tubular liposome increases. This is consistent with the experimental observation that the separation between rings is proportional to the radius of the liposome. Our model predicts that the mechanism for the increased rate of coarsening in liposomes of larger radius is a consequence of the increased interface energy. PMID:26105960

  14. Genetics Home Reference: ring chromosome 14 syndrome

    MedlinePlus

    ... characterized by seizures and intellectual disability. Recurrent seizures (epilepsy) develop in infancy or early childhood. In many ... to the signs and symptoms of this disorder. Epilepsy is a common feature of ring chromosome syndromes, ...

  15. Drechslerella stenobrocha genome illustrates the mechanism of constricting rings and the origin of nematode predation in fungi

    PubMed Central

    2014-01-01

    Background Nematode-trapping fungi are a unique group of organisms that can capture nematodes using sophisticated trapping structures. The genome of Drechslerella stenobrocha, a constricting-ring-forming fungus, has been sequenced and reported, and provided new insights into the evolutionary origins of nematode predation in fungi, the trapping mechanisms, and the dual lifestyles of saprophagy and predation. Results The genome of the fungus Drechslerella stenobrocha, which mechanically traps nematodes using a constricting ring, was sequenced. The genome was 29.02 Mb in size and was found rare instances of transposons and repeat induced point mutations, than that of Arthrobotrys oligospora. The functional proteins involved in nematode-infection, such as chitinases, subtilisins, and adhesive proteins, underwent a significant expansion in the A. oligospora genome, while there were fewer lectin genes that mediate fungus-nematode recognition in the D. stenobrocha genome. The carbohydrate-degrading enzyme catalogs in both species were similar to those of efficient cellulolytic fungi, suggesting a saprophytic origin of nematode-trapping fungi. In D. stenobrocha, the down-regulation of saprophytic enzyme genes and the up-regulation of infection-related genes during the capture of nematodes indicated a transition between dual life strategies of saprophagy and predation. The transcriptional profiles also indicated that trap formation was related to the protein kinase C (PKC) signal pathway and regulated by Zn(2)–C6 type transcription factors. Conclusions The genome of D. stenobrocha provides support for the hypothesis that nematode trapping fungi evolved from saprophytic fungi in a high carbon and low nitrogen environment. It reveals the transition between saprophagy and predation of these fungi and also proves new insights into the mechanisms of mechanical trapping. PMID:24507587

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

    PubMed

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

    2016-06-01

    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

  17. 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

  18. Ring 17 syndrome: first clinical report without intellectual disability.

    PubMed

    de Palma, Luca; De Carlo, Debora; Lenzini, Elisabetta; Boniver, Clementina; Tarantino, Vincenza; Bacci, Barbara; Vecchi, Marilena

    2015-03-01

    Ring chromosomes are rare abnormalities caused by the fusion of the telomeric regions. Three-ring chromosome syndromes (Cr 20, Cr 17 and Cr 14) cause epilepsy with variable phenotypes. In ring 17 patients with mild phenotype, some authors have shown an epilepsy syndrome similar to that of ring 20. We report the first case of a girl with ring chromosome 17 and a normal neurological and general cognitive profile. She had had, from 9 years old, focal pharmacoresistant epilepsy associated with episodes of non-convulsive status epilepticus with mainly autonomic features. Cytogenetic analysis revealed an abnormal karyotype characterised by the presence of de novo ring chromosome 17 in 19% of metaphases. The array CGH (100 KB) did not show any genetic deletion. The clinical and epilepsy phenotype was, to a certain degree, similar to that of ring 20 syndrome. PMID:25635406

  19. [Posterior reversible encephalopathy syndrome and cerebrovascular constriction syndrome in the differential diagnosis of post-partum headaches].

    PubMed

    Ruiz López, N; Cano Hernández, B; Balbás Álvarez, S

    2016-02-01

    Postpartum headache can be due to many causes. In a patient with previous epidural analgesia, the headache can be attributed to post-dural puncture headache, even if the symptoms are not typical of this clinical entity. We report a case of a post-partum with accidental dural tap during the insertion of an epidural catheter for labour analgesia, and who referred to headaches in the third post-partum day. Initially, a post-dural puncture headache was suspected, but the subsequent onset of seizures and visual impairment meant that the diagnosis had to be reconsidered. In this case report, the clinical and pathophysiological features of posterior reversible encephalopathy syndrome and reversible cerebral vasoconstriction syndrome, as well as the differential diagnosis of post-partum headaches are described. PMID:26056067

  20. 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

  1. 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)

  2. Median Facial Cleft in Amniotic Band Syndrome

    PubMed Central

    Das, Debabrata; Das, Gobinda; Gayen, Sibnath; Konar, Arpita

    2011-01-01

    Amniotic band syndrome manifests at birth with a variety of malformations ranging from constriction ring to defects incompatible to life, in various parts of the body. Although some theories have been proposed for the development of this syndrome, the exact cause remains unknown. The median facial cleft is an extremely rare manifestation of amniotic band syndrome with a relative paucity of reports available in the literature. Here, we report one such case. PMID:21731335

  3. Telomere shortening and telomere position effect in mild ring 17 syndrome

    PubMed Central

    2014-01-01

    Background Ring chromosome 17 syndrome is a rare disease that arises from the breakage and reunion of the short and long arms of chromosome 17. Usually this abnormality results in deletion of genetic material, which explains the clinical features of the syndrome. Moreover, similar phenotypic features have been observed in cases with complete or partial loss of the telomeric repeats and conservation of the euchromatic regions. We studied two different cases of ring 17 syndrome, firstly, to clarify, by analyzing gene expression analysis using real-time qPCR, the role of the telomere absence in relationship with the clinical symptoms, and secondly, to look for a new model of the mechanism of ring chromosome transmission in a rare case of familial mosaicism, through cytomolecular and quantitative fluorescence in-situ hybridization (Q-FISH) investigations. Results The results for the first case showed that the expression levels of genes selected, which were located close to the p and q ends of chromosome 17, were significantly downregulated in comparison with controls. Moreover, for the second case, we demonstrated that the telomeres were conserved, but were significantly shorter than those of age-matched controls; data from segregation analysis showed that the ring chromosome was transmitted only to the affected subjects of the family. Conclusions Subtelomeric gene regulation is responsible for the phenotypic aspects of ring 17 syndrome; telomere shortening influences the phenotypic spectrum of this disease and strongly contributes to the familial transmission of the mosaic ring. Together, these results provide new insights into the genotype-phenotype relationships in mild ring 17 syndrome. PMID:24393457

  4. [A report of 2 cases of Turner's syndrome with a ring X chromosome].

    PubMed

    Migliori, M V; Bartolotta, E; Maurizi, M; Bonazzi, P; Cardinale, G; Manunza, V

    1991-09-01

    The authors report two cases of Turner syndrome with clinical evidence of only primitive hypogonadism and short stature. Karyotype analysis showed X ring mosaicism which is present only in 5% of cases of Turner syndrome. The authors agree with the hypothesis suggesting no relationship between break points on the X chromosome and phenotypical aspect. An earlier diagnosis is auspicious so that, using correct therapy, final height should be improved. PMID:1758399

  5. Frontal motor seizure following non-convulsive status epilepticus in ring chromosome 20 syndrome.

    PubMed

    Kamoun, Fatma F; Ellouz, Emna J; Hsairi, Ines G; Triki, Chahnez C

    2012-01-01

    The ring chromosome 20 syndrome is a rare syndrome characterized by intractable epilepsy with particular electro clinical features including episodes of prolonged confusional state and nocturnal frontal lobe seizures. We report a 17-year-old girl who had intractable epilepsy with frontal seizure and prolonged confusional state secondary to non-convulsive status epilepticus. The diagnosis of ring chromosome 20 was suspected and confirmed by karyotype. The cytogenetic study of CHRNA4 and KCNQ2 genes did not detect deletion in the ring chromosome 20. During video-EEG recording, this girl presented a non-convulsive status epilepticus that lasted more than 20 minutes followed by typical frontal lobe seizure. This association was not previously described, and was probably caused by chromosomal instability. PMID:22246017

  6. Invasive hemodynamics of constrictive pericarditis

    PubMed Central

    Doshi, Shrenik; Ramakrishnan, Sivasubramanian; Gupta, Saurabh Kumar

    2015-01-01

    Cardiac catheterization and hemodynamic study is the gold standard for the diagnosis of pericardial constriction. Careful interpretation of the hemodynamic data is essential to differentiate it from other diseases with restrictive physiology. In this hemodynamic review we shall briefly discuss the physiologic basis of various hemodynamic changes seen in a patient with constrictive pericarditis. PMID:26071303

  7. Developmental regression in ring chromosome 20 syndrome: A prion disease?

    SciTech Connect

    Aughton, D.J.

    1994-09-01

    Since 1972, the occurrence of r(20) has been described in at least 22 patients. In contrast to the relatively early-onset and nonprogressive developmental delay typical of chromosomal syndromes generally, the development of patients with r(20) is often normal for many months or even years, and developmental regression has been observed in at least 3 cases. Herein I present a further instance of developmental regression associated with r(20), and suggest that such regression may owe to disruption of function of the prion protein gene [PRNP], which has been mapped to 20pter-p12. The proposita was born at 33 weeks of gestation but had a relatively uncomplicated neonatal course; her early development was normal. By age 8-2/12 years, she appeared to have some cognitive deficits; by age 9-7/12 years, she was considered to have educable mental retardation, with a behavior disorder. On physical examination at age 9-8/12 years, her weight was between p10 and p25, and her head circumference was ca. p50. She had very mild coarseness and hirsutism, but was not dysmorphic. Extensive investigation was largely unremarkable; however, fragile X chromosome analysis at age 11-6/12 years showed a 46,XX,r(20) karyotype [fra(X) negative] in each of 50 cells examined. The maternal karyotype was mos46,XX/46,XX,r(20). Molecular analysis of PRNP is in progress. Rivers et al. reported a progressive neurological disorder associated with a telomeric fusion 15p;20p, and suggested that the disorder might be secondary to the presence of a pathogenic isoform of the prion protein. I suggest that a similar mechanism may be responsible for the neurodegeneration sometimes associated with r(20) syndrome. Molecular analysis of PRNP in patients with r(20) syndrome and, when possible, pathologic examination of central nervous system tissue of these patients will be helpful in further assessing this hypothesis.

  8. Distinct 15q genotypes in Russell-Silver and ring 15 syndromes

    SciTech Connect

    Rogan, P.K.; Seip, J.R.; Driscoll, D.J.

    1996-03-01

    Individuals with a ring 15 chromosome [r(15)] and those with Russell-Silver syndrome have short stature, developmental delay, triangular face, and clinodactyly. To assess whether the apparent phenotypic overlap of these conditions reflects a common genetic cause, the extent of deletions in chromosome 15q was determined in 5 patients with r(15), 1 patient with del 15q26.1-qter, and 5 patients with Russell-Silver syndrome. All patient with Russell-Silver syndrome were diploid for genetic markers in distal 15q, indicating that Russell-Silver syndrome in these individuals was unlikely to be related to the expression of single alleles at these or linked genetic loci. At least 3 distinct sites of chromosome breakage close to the telomere were found in the r(15) and del 15q25.1-qter patients, with 1 r(15) patient having both a terminal and an interstitial deletion. Although the patient with del 15q25.1-qter exhibited the largest deletion and the most profound growth retardation, the degree of growth impairment among the r(15) patients was not correlated with the size of the deleted interval. Rather, the parental origin of the ring chromosome in several patients was associated with phenotypes that are also seen in patients with either Prader-Willi (PWS) or Angelman (AS) syndromes, conditions that result from uniparental expression of genes on chromosome 15. The PWS-like or AS-like phenotypes could be explained by postzygotic loss of the ring chromosome, leading to uniparental inheritance of the intact chromosome in some tissues of r(15) patients. 33 refs., 2 figs., 3 tabs.

  9. Emerging neuroimaging contribution to the diagnosis and management of the ring chromosome 20 syndrome.

    PubMed

    Vaudano, Anna Elisabetta; Ruggieri, Andrea; Vignoli, Aglaia; Canevini, Maria Paola; Meletti, Stefano

    2015-04-01

    Ring chromosome 20 [r(20)] syndrome is an underdiagnosed chromosomal anomaly characterized by severe epilepsy, behavioral problems, and mild-to-moderate cognitive deficits. Since the cognitive and behavioral decline follows seizure onset, this syndrome has been proposed as an epileptic encephalopathy (EE). The recent overwhelming development of advanced neuroimaging techniques has opened a new era in the investigation of the brain networks subserving the EEs. In particular, functional neuroimaging tools are well suited to show alterations related to epileptiform discharges at the network level and to build hypotheses about the mechanisms underlying the cognitive disruption observed in these conditions. This paper reviews the brain circuits and their disruption as revealed by functional neuroimaging studies in patients with [r(20)] syndrome. It discusses the clinical consequences of the neuroimaging findings on the management of patients with [r(20)] syndrome, including their impact to an earlier diagnosis of this disorder. Based on the available lines of evidences, [r(20)] syndrome is characterized by interictal and ictal dysfunctions within basal ganglia-prefrontal lobe networks and by long-lasting effects of the peculiar theta-delta rhythm, which represents an EEG marker of the syndrome on integrated brain networks that subserve cognitive functions. PMID:25843339

  10. Refractory and severe status epilepticus in a patient with ring chromosome 20 syndrome.

    PubMed

    Hirano, Yoshiko; Oguni, Hirokazu; Nagata, Satoru

    2016-09-01

    Ring chromosome 20 [r(20)] syndrome is a rare chromosomal disorder that is characterized by the development of refractory epilepsy during childhood with gradual declines in cognitive performance and behavior. Although the prognoses of seizures and intellectual disability associated with this condition are poor, life-threatening complications have rarely been described. We herein presented a case of a 17-year-old female with [r(20)] syndrome who developed recurrent status epilepticus (SE) at 14years of age that evolved into unremitting SE in spite of vigorous antiepileptic treatments. She was administered thiopental anesthesia for 1year, and was subsequently left in severe neurological sequelae. It is important to note that patients with this syndrome not only have severe epileptic encephalopathy persisting into adulthood, but are also at risk of fatal SE. PMID:26980640

  11. 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

  12. Mild ring 17 syndrome shares common phenotypic features irrespective of the chromosomal breakpoints location.

    PubMed

    Surace, C; Piazzolla, S; Sirleto, P; Digilio, M C; Roberti, M C; Lombardo, A; D'Elia, G; Tomaiuolo, A C; Petrocchi, S; Capolino, R; El Hachem, M; Claps Sepulveda, D; Sgura, A; Angioni, A

    2009-09-01

    Ring 17 syndrome is a rare disorder with clinical features influenced by the presence or deletion of the Miller-Dieker critical region (MDCR). Presence of the MDCR is associated with a mild phenotype, including growth delay (GD), mental retardation (MR), seizures, cafè au lait skin (CALS) spots and minor facial dysmorphisms. Previous studies have been mainly focused on this locus providing poor information about the role of other genes located on the p- and q-arms. Here, we used bacterial artificial chromosome (BAC)/P1 artificial chromosome (PAC) and fosmid clones as fluorescence in situ hybridization (FISH) probes to perform a cyto-molecular analysis of a ring 17 case and found that the breakpoints were close to the telomeric ends. METRNL is the sole gene located on the q-arm terminal end, whereas two open reading frames and the RPH3AL gene are located on the terminal p-arm. To detect possibly unrevealed small deletions involving the transcription units, we used subcloned FISH probes obtained by long-range polymerase chain reaction (PCR), which showed that the investigated regions were preserved. Comparing our findings with other reports, it emerges that different breakpoints, involving (or not) large genomic deletions, present overlapping clinical aspects. In conclusion, our data suggest that a mechanism based on gene expression control besides haploinsufficiency should be considered to explain the common phenotypic features found in the mild ring 17 syndrome. PMID:19793054

  13. 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

  14. SF3B1 mutation identifies a distinct subset of myelodysplastic syndrome with ring sideroblasts

    PubMed Central

    Karimi, Mohsen; Papaemmanuil, Elli; Ambaglio, Ilaria; Jädersten, Martin; Jansson, Monika; Elena, Chiara; Gallì, Anna; Walldin, Gunilla; Della Porta, Matteo G.; Raaschou-Jensen, Klas; Travaglino, Erica; Kallenbach, Klaus; Pietra, Daniela; Ljungström, Viktor; Conte, Simona; Boveri, Emanuela; Invernizzi, Rosangela; Rosenquist, Richard; Campbell, Peter J.; Cazzola, Mario; Hellström Lindberg, Eva

    2015-01-01

    Refractory anemia with ring sideroblasts (RARS) is a myelodysplastic syndrome (MDS) characterized by isolated erythroid dysplasia and 15% or more bone marrow ring sideroblasts. Ring sideroblasts are found also in other MDS subtypes, such as refractory cytopenia with multilineage dysplasia and ring sideroblasts (RCMD-RS). A high prevalence of somatic mutations of SF3B1 was reported in these conditions. To identify mutation patterns that affect disease phenotype and clinical outcome, we performed a comprehensive mutation analysis in 293 patients with myeloid neoplasm and 1% or more ring sideroblasts. SF3B1 mutations were detected in 129 of 159 cases (81%) of RARS or RCMD-RS. Among other patients with ring sideroblasts, lower prevalence of SF3B1 mutations and higher prevalence of mutations in other splicing factor genes were observed (P < .001). In multivariable analyses, patients with SF3B1 mutations showed significantly better overall survival (hazard ratio [HR], .37; P = .003) and lower cumulative incidence of disease progression (HR = 0.31; P = .018) compared with SF3B1-unmutated cases. The independent prognostic value of SF3B1 mutation was retained in MDS without excess blasts, as well as in sideroblastic categories (RARS and RCMD-RS). Among SF3B1-mutated patients, coexisting mutations in DNA methylation genes were associated with multilineage dysplasia (P = .015) but had no effect on clinical outcome. TP53 mutations were frequently detected in patients without SF3B1 mutation, and were associated with poor outcome. Thus, SF3B1 mutation identifies a distinct MDS subtype that is unlikely to develop detrimental subclonal mutations and is characterized by indolent clinical course and favorable outcome. PMID:25957392

  15. Rings

    SciTech Connect

    Davis, R.L.

    1989-01-01

    The essence of vortex physics is that at certain low-energy scales elementary excitations of a point particle theory can behave like strings rather than particles. Vortices are the resulting string-like solutions; their thickness sets the distance scale beyond which physics is string-like rather than particle-like. String degrees of freedom are massless in the sense that excitations on a string can have an arbitrarily low frequency. Non-string degrees of freedom correspond to massive particles and are absent from the low energy spectrum. This article considers only field theories with vortices at low energies. The possible existence of a class of solitons in these vortex theories will be discussed. They are vortex rings: they are localized and finite in energy, and able to carry the quantum numbers of point particles. Rings are thus particle-like solutions of a vortex theory, which is itself a limit of a point particle field theory.

  16. Gelastic seizures in ring chromosome 20 syndrome: a case report with video illustration.

    PubMed

    Dimova, Petia; Boneva, Iliyana; Todorova, Albena; Minotti, Lorella; Kahane, Philippe

    2012-06-01

    Although increasingly recognised, ring chromosome 20 (r[20]) syndrome is still diagnosed with delay, sometimes leading to inappropriate presurgical evaluation. The focal, presumed frontal, character of the seizures manifesting with fear and hypermotor behaviour and episodes of non-convulsive status epilepticus (NCSE) are most typical, as well as cognitive impairment with behavioural problems and, sometimes, dysmorphic signs. We present a girl diagnosed at the age of 13 years who suffered from an atypical clinical presentation, with minimal cognitive problems, absence of dysmorphic symptoms, and hypermotor/gelastic seizures. [Published with video sequences]. PMID:22591830

  17. Potential flow through channel constriction.

    USGS Publications Warehouse

    Lee, J.K.

    1984-01-01

    Potential flow through an eccentric, normal constriction of zero thickness in an infinitely long, straight channel of constant width and unit depth is studied by use of a Schwarz-Christoffel transformation. The transformation is integrated by a direct approach. Parametric equations for streamlines are obtained and used to compute an average streamline length for a potential-flow field. -from ASCE Publications Information

  18. Long-term EEG in patients with the ring chromosome 20 epilepsy syndrome.

    PubMed

    Freire de Moura, Maria; Flores-Guevara, Roberto; Gueguen, Bernard; Biraben, Arnaud; Renault, Francis

    2016-05-01

    The recognizable electroencephalography (EEG) pattern of ring chromosome 20 epilepsy syndrome can be missing in patients with r(20) chromosomal anomaly, and may be found in patients with frontal lobe epilepsy of other origin. This study aims to search for more specific EEG signs by using long-term recordings and measuring the duration of paroxysmal anomalies. The series included 12 adult patients with r(20) anomaly, and 12 controls without any chromosomal aberration. We measured the duration of every paroxysmal burst and calculated the sum of their durations for each long-term EEG recording. We compared patients to controls using the Mann-Whitney U-test. Every patient showed long-lasting paroxysmal EEG bursts, up to 60 min; controls did not show any bursts longer than 60 s (p < 0.0001). The total duration of paroxysmal anomalies was significantly longer in patients (31-692 min) compared to controls (0-48 min) (p < 0.0001). Thus, long-term recordings enhance the contribution of EEG methods for characterizing the ring 20 chromosome epilepsy syndrome. PMID:27009934

  19. Minute supernumerary ring chromosome 22 associated with cat eye syndrome: Further delineation of the critical region

    SciTech Connect

    Mears, A.J.; McDermid, H.E.; El-Shanti, H.

    1995-09-01

    Cat eye syndrome (CES) is typically associated with a supernumerary bisatellited marker chromosome (inv dup 22pter-22q11.2) resulting in four copies of this region. We describe an individual showing the inheritance of a minute supernumerary double ring chromosome 22, which resulted in expression of all cardinal features of CES. The size of the ring was determined by DNA dosage analysis and FISH analysis for five loci mapping to 22q11.2. The probes to the loci D22S9, D22S43, and ATP6E were present in four copies, whereas D22S57 and D22S181 were present in two copies. This finding further delineates the distal boundary of the critical region of CES, with ATP6E being the most distal duplicated locus identified. The phenotypically normal father and grandfather of the patient each had a small supernumerary ring chromosome and demonstrated three copies for the loci D22S9, D22S43, and ATP6E. Although three copies of this region have been reported in other cases with CES features, it is possible that the presence of four copies leads to greater susceptibility. 35 refs., 4 figs., 2 tabs.

  20. 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.

  1. Theoretical analysis of ARC constriction

    SciTech Connect

    Stoenescu, M.L.; Brooks, A.W.; Smith, T.M.

    1980-12-01

    The physics of the thermionic converter is governed by strong electrode-plasma interactions (emissions surface scattering, charge exchange) and weak interactions (diffusion, radiation) at the maximum interelectrode plasma radius. The physical processes are thus mostly convective in thin sheaths in front of the electrodes and mostly diffusive and radiative in the plasma bulk. The physical boundaries are open boundaries to particle transfer (electrons emitted or absorbed by the electrodes, all particles diffusing through some maximum plasma radius) and to convective, conductive and radiative heat transfer. In a first approximation the thermionic converter may be described by a one-dimensional classical transport theory. The two-dimensional effects may be significant as a result of the sheath sensitivity to radial plasma variations and of the strong sheath-plasma coupling. The current-voltage characteristic of the converter is thus the result of an integrated current density over the collector area for which the boundary conditions at each r determine the regime (ignited/unignited) of the local current density. A current redistribution strongly weighted at small radii (arc constriction) limits the converter performance and opens questions on constriction reduction possibilities. The questions addressed are the followng: (1) what are the main contributors to the loss of current at high voltage in the thermionic converter; and (2) is arc constriction observable theoretically and what are the conditions of its occurrence. The resulting theoretical problem is formulated and results are given. The converter electrical current is estimated directly from the electron and ion particle fluxes based on the spatial distribution of the electron/ion density n, temperatures T/sub e/, T/sub i/, electrical voltage V and on the knowledge of the transport coefficients. (WHK)

  2. [A case of constrictive bronchiolitis].

    PubMed

    Kikuchi, Misato; Koyama, Shinichiro; Toyoda, Akira; Kawabata, Yoshinori

    2004-11-01

    A 31-year-old woman was admitted to our hospital because of a dry cough and progressive exertional dyspnea after her second delivery. She had almost normal laboratory data except for an elevated value for antibody for nucleic acid, and her chest radiograph was normal. However, pulmonary function tests revealed a mixed pattern of dysfunction, and chest CT revealed a mosaic perfusion pattern. The VATS lung biopsy demonstrated complete occlusion of the membranous bronchiole. These results led to a diagnosis of constrictive bronchiolitis (CB). The patient and her family rejected the option of lung transplantation, and selected immunosuppressive therapy (steroid pulse therapy and cyclophosphamide pulse therapy). Her condition improved temporarily, but her respiratory condition worsened progressively, and finally she died one and a half years after the appearance of the symptoms. Although steroid pulse therapy and cyclophosphamide pulse therapy failed to cure the CB, they did retard its progression. PMID:15651275

  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. Constrictive Pericarditis Long after a Gunshot Wound.

    PubMed

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

    2015-07-01

    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

  5. Using a Distant Abdominal Skin Flap to Treat Digital Constriction Bands

    PubMed Central

    Zhang, Mingzi; Song, Kexin; Ding, Ning; Shu, Chang; Wang, Youbin

    2016-01-01

    Abstract In this study, a Vohwinkel syndrome case is presented where in 5th digit constriction bands in the right hand were reconstructed using a distant abdominal skin flap. Vohwinkel syndrome, or keratoderma hereditarium mutilans, is a rare, autosomal dominant genetic skin condition that causes palmoplantar hyperkeratosis and constricts finger and/or toe bands. In a typical manifestation, the finger and toe constriction bands lead to progressive strangulation and autoamputation, which requires immediate clinical treatment. Topical keratolytics and systemic retinoids have been used to treat hyperkeratosis but without consistent results. Only 1 effective approach for autoamputation has been accepted, reconstructive surgery. Applying a distant abdominal skin flap produced satisfying postoperative effects at the 18-month follow-up. PMID:26871826

  6. Intrasaccadic perception triggers pupillary constriction.

    PubMed

    Mathôt, Sebastiaan; Melmi, Jean-Baptiste; Castet, Eric

    2015-01-01

    It is commonly believed that vision is impaired during saccadic eye movements. However, here we report that some visual stimuli are clearly visible during saccades, and trigger a constriction of the eye's pupil. Participants viewed sinusoid gratings that changed polarity 150 times per second (every 6.67 ms). At this rate of flicker, the gratings were perceived as homogeneous surfaces while participants fixated. However, the flickering gratings contained ambiguous motion: rightward and leftward motion for vertical gratings; upward and downward motion for horizontal gratings. When participants made a saccade perpendicular to the gratings' orientation (e.g., a leftward saccade for a vertical grating), the eye's peak velocity matched the gratings' motion. As a result, the retinal image was approximately stable for a brief moment during the saccade, and this gave rise to an intrasaccadic percept: A normally invisible stimulus became visible when eye velocity was maximal. Our results confirm and extend previous studies by demonstrating intrasaccadic perception using a reflexive measure (pupillometry) that does not rely on subjective report. Our results further show that intrasaccadic perception affects all stages of visual processing, from the pupillary response to visual awareness. PMID:26339536

  7. SF3B1 haploinsufficiency leads to formation of ring sideroblasts in myelodysplastic syndromes

    PubMed Central

    Visconte, Valeria; Rogers, Heesun J.; Singh, Jarnail; Barnard, John; Bupathi, Manoj; Traina, Fabiola; McMahon, James; Makishima, Hideki; Szpurka, Hadrian; Jankowska, Anna; Jerez, Andres; Sekeres, Mikkael A.; Saunthararajah, Yogen; Advani, Anjali S.; Copelan, Edward; Koseki, Haruhiko; Isono, Kyoichi; Padgett, Richard A.; Osman, Sami; Koide, Kazunori; O'Keefe, Christine; Maciejewski, Jaroslaw P.

    2012-01-01

    Whole exome/genome sequencing has been fundamental in the identification of somatic mutations in the spliceosome machinery in myelodysplastic syndromes (MDSs) and other hematologic disorders. SF3B1, splicing factor 3b subunit 1 is mutated in 60%-80% of refractory anemia with ring sideroblasts (RARS) and RARS associated with thrombocytosis (RARS-T), 2 distinct subtypes of MDS and MDS/myeloproliferative neoplasms (MDSs/MPNs). An idiosyncratic feature of RARS/RARS-T is the presence of abnormal sideroblasts characterized by iron overload in the mitochondria, called RS. Based on the high frequency of mutations of SF3B1 in RARS/RARS-T, we investigated the consequences of SF3B1 alterations. Ultrastructurally, SF3B1 mutants showed altered iron distribution characterized by coarse iron deposits compared with wild-type RARS patients by transmission electron microscopy. SF3B1 knockdown experiments in K562 cells resulted in down-regulation of U2-type intron-splicing by RT-PCR. RNA-sequencing analysis of SF3B1 mutants showed differentially used genes relevant in MDS pathogenesis, such as ASXL1, CBL, EZH, and RUNX families. A SF3B pharmacologic inhibitor, meayamycin, induced the formation of RS in healthy BM cells. Further, BM aspirates of Sf3b1 heterozygous knockout mice showed RS by Prussian blue. In conclusion, we report the first experimental evidence of the association between SF3B1 and RS phenotype. Our data suggest that SF3B1 haploinsufficiency leads to RS formation. PMID:22826563

  8. 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?

  9. 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?

  10. Ascending Aortic Constriction in Rats for Creation of Pressure Overload Cardiac Hypertrophy Model

    PubMed Central

    S, Santhosh Kumar; G, Sanjay; Kartha, Chandrasekharan Cheranellore

    2014-01-01

    Ascending aortic constriction is the most common and successful surgical model for creating pressure overload induced cardiac hypertrophy and heart failure. Here, we describe a detailed surgical procedure for creating pressure overload and cardiac hypertrophy in rats by constriction of the ascending aorta using a small metallic clip. After anesthesia, the trachea is intubated by inserting a cannula through a half way incision made between two cartilage rings of trachea. Then a skin incision is made at the level of the second intercostal space on the left chest wall and muscle layers are cleared to locate the ascending portion of aorta. The ascending aorta is constricted to 50–60% of its original diameter by application of a small sized titanium clip. Following aortic constriction, the second and third ribs are approximated with prolene sutures. The tracheal cannula is removed once spontaneous breathing was re-established. The animal is allowed to recover on the heating pad by gradually lowering anesthesia. The intensity of pressure overload created by constriction of the ascending aorta is determined by recording the pressure gradient using trans-thoracic two dimensional Doppler-echocardiography. Overall this protocol is useful to study the remodeling events and contractile properties of the heart during the gradual onset and progression from compensated cardiac hypertrophy to heart failure stage. PMID:24998889

  11. 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.

  12. Plasma proteome changes associated with refractory anemia and refractory anemia with ringed sideroblasts in patients with myelodysplastic syndrome

    PubMed Central

    2013-01-01

    Background Refractory anemia and refractory anemia with ringed sideroblasts are two myelodysplastic syndrome (MDS) subgroups linked with anemia. MDS is a group of heterogeneous oncohematological bone marrow disorders characterized by ineffective hematopoiesis, blood cytopenias, and progression of the disease toward acute myeloid leukemia. The aim of this study was to search for plasma proteome changes in MDS patients with refractory anemia and refractory anemia with ringed sideroblasts. Results A total of 26 patient and healthy donor plasma samples were depleted of fourteen high-abundant plasma proteins, separated with 2D electrophoresis, and statistically processed with Progenesis SameSpots software. 55 significantly differing spots were observed and corresponded to 39 different proteins identified by nanoLC-MS/MS. Changes in the fragments of the inter-alpha-trypsin inhibitor heavy chain H4 protein were observed. Using mass spectrometry-based relative label-free quantification of tryptic peptides, there were differences in alpha-2-HS-glycoprotein peptides, while no differences were observed between the control and patient sample groups for retinol-binding protein 4 peptides. Conclusions This study describes plasma proteome changes associated with MDS patients with refractory anemia and refractory anemia with ringed sideroblasts. Changes observed in the inter-alpha-trypsin inhibitor heavy chain H4 fragments were in agreement with our previous studies of other MDS subgroups: refractory cytopenia with multilineage dysplasia and refractory anemia with excess blasts subtype 1. Mass spectrometry-based relative quantification of retinol-binding protein 4 peptides has shown that there are differences in the modification of this protein between refractory anemia with excess blasts subtype 1 patients and MDS patients with refractory anemia and refractory anemia with ringed sideroblasts. Alpha-2-HS-glycoprotein seems to be a new potential MDS biomarker candidate. PMID

  13. High-frequency constricted mesa lasers

    SciTech Connect

    Bowers, J.E.; Hemenway, B.R.; Gnauck, A.H.; Bridges, T.J.; Burkhardt, E.G.; Wilt, D.P.; Maynard, S.

    1985-07-15

    InGaAsP cw constricted mesa lasers at 1.3 ..mu..m are described which have a small-signal 3-dB bandwidth of 20 GHz at -70 /sup 0/C. Large-signal pseudorandom modulation at 8 Gb/s resulted in 100% optical modulation. The lasers were gain switched at 12 GHz with 100% optical modulation.

  14. [Cardiac tumor, constrictive pericarditis and pulmonary thromboembolism].

    PubMed

    Takano, Tamaki; Amano, Jun

    2011-07-01

    Cardiac tumors are rare, and 3-quarters of these tumors are benign and nearly half of the benign tumors are myxomas. Metastases to the heart are more common than primary cardiac tumors. Cardiac tumors present obstructive, constitutional and embolic signs and symptoms. Echocardiograms, chest computed tomography (CT) and magnetic resonance imaging (MRI) scan are very useful for diagnosis. Surgery is indicated in patients with benign tumor, and chemo/radio-therapy in patients with malignant tumors. Prognosis after surgery is good, instead poor prognosis for patients with malignancy. Constrictive pericarditis is mainly result of idiopathic, previous cardiac surgery and radiation in recent years. Diagnosis is made by echo cardiography and cardiac catheterization along with clinical presentation. Thickened pericardium is directly diagnosed by currently advanced transesophageal echocardiography, CT and MRI although normal thickness of the pericardium with constrictive pericarditis is observed in some patients. Pericardiectomy is the only treatment for permanent constriction. The incidence of pulmonary thromboembolism is currently increasing in Japan. Guidelines for the diagnosis, treatment and prevention of pulmonary thromboembolism and deep vein thrombosis (JCS 2009) is helpful for diagnosis and treatment decision. Anticoagulant is initial treatment for acute pulmonary thromboembolism, and intravenous thrombolysis is performed in hemodynamically unstable cases. Chronic thromboembolic pulmonary hypertention is treated by pulmonary endarterectomy whereas anticoagulant and vasodilator are used for peripheral type and mild cases. PMID:21916175

  15. Effects of nanosized constriction on thermal transport properties of graphene

    PubMed Central

    2014-01-01

    Thermal transport properties of graphene with nanosized constrictions are investigated using nonequilibrium molecular dynamics simulations. The results show that the nanosized constrictions have a significant influence on the thermal transport properties of graphene. The thermal resistance of the nanosized constrictions is on the order of 107 to 109 K/W at 150 K, which reduces the thermal conductivity by 7.7% to 90.4%. It is also found that the constriction resistance is inversely proportional to the width of the constriction and independent of the heat current. Moreover, we developed an analytical model for the ballistic thermal resistance of the nanosized constrictions in two-dimensional nanosystems. The theoretical prediction agrees well with the simulation results in this paper, which suggests that the thermal transport across the nanosized constrictions in two-dimensional nanosystems is ballistic in nature. PACS 65.80.CK; 61.48.Gh; 63.20.kp; 31.15.xv PMID:25232292

  16. Myelodysplastic syndrome without ring sideroblasts and with Janus kinase 2 gene mutation: An unusual case report

    PubMed Central

    Ornellas, Maria Helena; De França Silva, Monique; Solza, Cristiana; De Lucena Gonçalves, Stella Beatriz Sampaio; Silva De Almeida, Liliane; De Paula Ayres-Silva, Jackline; Seixas, Taís Leite; Bastos, Elenice Ferreira; Liehr, Thomas; Alves, Gilda

    2016-01-01

    Myelodysplastic syndrome (MDS) cases comprise a heterogeneous group of hematological disorders that are characterized by impaired hematopoiesis, with cytopenias of different grades and risk of developing acute myeloid leukemia. MDS may rarely be associated with thrombocytosis. In such cases, myelodysplasia and myeloproliferative disorders may overlap, making correct diagnosis difficult. We herein describe a case of MDS with thrombocytosis, Janus kinase 2 gene mutation-positive and Perls' staining-negative, which was initially classified as essential thrombocythemia (ET). This case highlights that MDS may be misdiagnosed as ET and inappropriate treatment may be initiated. Therefore, it is crucial to carefully combine all available data on morphology and immunophenotyping, and to perform the necessary molecular, cytogenetic and molecular cytogenetic analyses, in order to correctly diagnose this disease.

  17. 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

  18. Diagnosis and classification of myelodysplastic syndrome: International Working Group on Morphology of myelodysplastic syndrome (IWGM-MDS) consensus proposals for the definition and enumeration of myeloblasts and ring sideroblasts.

    PubMed

    Mufti, Ghulam J; Bennett, John M; Goasguen, Jean; Bain, Barbara J; Baumann, Irith; Brunning, Richard; Cazzola, Mario; Fenaux, Pierre; Germing, Ulrich; Hellström-Lindberg, Eva; Jinnai, Itsuro; Manabe, Atsushi; Matsuda, Akira; Niemeyer, Charlotte M; Sanz, Guillermo; Tomonaga, Masao; Vallespi, Teresa; Yoshimi, Ayami

    2008-11-01

    The classification of myelodysplastic syndromes is based on the morphological criteria proposed by the French-American-British (FAB) and World Health Organization (WHO) groups. Accurate enumeration of blast cells, although essential for diagnosis of myelodysplastic syndrome and for assignment to prognostic groups, is often difficult, due to imprecise criteria for the morphological definition of blasts and promyelocytes. An International Working Group on Morphology of Myelodysplastic Syndrome (IWGM-MDS) of hematopathologists and hematologists expert in the field of myelodysplastic syndrome reviewed the morphological features of bone marrows from all subtypes of myelodysplastic syndrome and agreed on a set of recommendations, including recommendations for the definition and enumeration of blast cells and ring sideroblasts. It is recommended that (1) agranular or granular blast cells be defined (replacing the previous type I, II and III blasts), (2) dysplastic promyelocytes be distinguished from cytologically normal promyelocytes and from granular blast cells, (3) sufficient cells be counted to give a precise blast percentage, particularly at thresholds that are important for diagnosis or prognosis and (4) ring sideroblasts be defined as erythroblasts in which there are a minimum of 5 siderotic granules covering at least a third of the nuclear circumference. Clear definitions and a differential count of a sufficient number of cells is likely to improve precision in the diagnosis and classification of myelodysplastic syndrome. Recommendations should be applied in the context of the WHO classification. PMID:18838480

  19. Numerical computation of pulsatile flow through a locally constricted channel

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, S.; Layek, G. C.

    2011-01-01

    This paper deals with the numerical solution of a pulsatile laminar flow through a locally constricted channel. A finite difference technique has been employed to solve the governing equations. The effects of the flow parameters such as Reynolds number, flow pulsation in terms of Strouhal number, constriction height and length on the flow behaviour have been studied. It is found that the peak value of the wall shear stress has significantly changed with the variation of Reynolds numbers and constriction heights. It is also noted that the Strouhal number and constriction length have little effect on the peak value of the wall shear stress. The flow computation reveals that the peak value of the wall shear stress at maximum flow rate time in pulsatile flow situation is much larger than that due to steady flow. The constriction and the flow pulsation produce flow disturbances at the vicinity of the constriction of the channel in the downstream direction.

  20. Controlling hysteresis in superconducting constrictions with a resistive shunt

    NASA Astrophysics Data System (ADS)

    Kumar, Nikhil; Winkelmann, C. B.; Biswas, Sourav; Courtois, H.; Gupta, Anjan K.

    2015-07-01

    We demonstrate control of the thermal hysteresis in superconducting constrictions by adding a resistive shunt. In order to prevent thermal relaxation oscillations, the shunt resistor is placed in close proximity to the constriction, making the inductive current-switching time smaller than the thermal equilibration time. We investigate the current-voltage characteristics of the same constriction with and without the shunt-resistor. The widening of the hysteresis-free temperature range is explained on the basis of a simple model.

  1. 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. PMID:22258447

  2. Exercise-induced airways constriction 1

    PubMed Central

    Simonsson, Bo G.; Skoogh, B-E.; Ekström-Jodal, B.

    1972-01-01

    Airway conductance was measured in a body plethysmograph at different lung volumes before and after graded exercise. In 14 out of 19 patients, mostly asthmatics, airway conductance fell significantly after exercise. These subjects also showed other signs of an increased bronchial reactivity to different stimuli, including forced breathing, hyperventilation, and cold air, but they had no exogenous allergy. The exercise-induced bronchoconstriction could be blocked by atropine in six of the nine patients tested. Exercise-induced bronchoconstriction in patients with clinical and physiological evidence of increased airway reactivity thus seems to be primarily mediated via a vagal reflex, probably from hyperresponsive airway mechanoreceptors reacting to increased ventilatory flow or lung distension. No relation was found between PaCO2 or pH and the severity of airways constriction. Cromoglycic acid failed to block the exercise reaction in five of the six hyperreactive patients tested. In addition to or following the vagal reflex a disturbed relation between beta and alpha receptors in bronchial muscles or a release of humoral spasmogens may contribute to the progression of post-exercise airways constriction. PMID:4624586

  3. 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

  4. 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.

  5. Vascular rings.

    PubMed

    Backer, Carl L; Mongé, Michael C; Popescu, Andrada R; Eltayeb, Osama M; Rastatter, Jeffrey C; Rigsby, Cynthia K

    2016-06-01

    The term vascular ring refers to congenital vascular anomalies of the aortic arch system that compress the esophagus and trachea, causing symptoms related to those two structures. The most common vascular rings are double aortic arch and right aortic arch with left ligamentum. Pulmonary artery sling is rare and these patients need to be carefully evaluated for frequently associated tracheal stenosis. Another cause of tracheal compression occurring only in infants is the innominate artery compression syndrome. In the current era, the diagnosis of a vascular ring is best established by CT imaging that can accurately delineate the anatomy of the vascular ring and associated tracheal pathology. For patients with a right aortic arch there recently has been an increased recognition of a structure called a Kommerell diverticulum which may require resection and transfer of the left subclavian artery to the left carotid artery. A very rare vascular ring is the circumflex aorta that is now treated with the aortic uncrossing operation. Patients with vascular rings should all have an echocardiogram because of the incidence of associated congenital heart disease. We also recommend bronchoscopy to assess for additional tracheal pathology and provide an assessment of the degree of tracheomalacia and bronchomalacia. The outcomes of surgical intervention are excellent and most patients have complete resolution of symptoms over a period of time. PMID:27301603

  6. Difficulties in diagnosing chronic constrictive pericarditis

    PubMed Central

    Vasile, I.; Negulescu, M.; Florescu, G.; Ionescu, R.; Berbecaru, S.

    2004-01-01

    This presentation calls attention to the many problems involved in the positive, aetiological and differential diagnosis of chronic constrictive pericarditis. We mention the difficulties in aetiological diagnosis in the absence of an episode of acute pericarditis in the past medical history and the clinical findings similar to vascular decompensated cirrhosis or idiopathic restrictive cardiomyopathy. ECG and two-dimensional echocardiography do not have an important role in diagnosis, and in the absence of computed tomography and magnetic resonance imaging, chest radiography, especially a lateral view, could establish the diagnosis. A delay in diagnosis creates difficulties in the surgical treatment, but this treatment improves the patient's condition in the long term more than the short term. ImagesFigure 1Figure 2 PMID:25696284

  7. 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.

  8. 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

  9. Analytical results for cell constriction dominated by bending energy.

    PubMed

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

    2015-01-01

    Analytical expressions are obtained for the main magnitudes of a symmetrically constricted vesicle. These equations provide an easy and compact way to predict minimal requirements for successful constriction and its main magnitudes. Thus, they can be useful for the design of synthetic divisomes and give good predictions for magnitudes including constriction energy, length of the constriction zone, volume and area of the vesicle, and the stability coefficient for symmetric constriction. The analytical expressions are derived combining a perturbative expansion in the Lagrangian for small deformations with a cosine ansatz in the constriction region. Already the simple fourth-order (or sixth-order) approximation provides a good approximation to the values of the main physical magnitudes during constriction, as we show through comparison with numerical results. Results are for vesicles with negligible effects from spontaneous curvature, surface tension, and pressure differences. This is the case when membrane components generating spontaneous curvature are scarce, membrane trafficking is present with low energetic cost, and the external medium is isotonic. PMID:25679648

  10. 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. PMID:26202779

  11. Constricted Canals: A New Strategy to Overcome This Challenge

    PubMed Central

    Silva, Emmanuel João Nogueira Leal; Vansan, Luiz Pascoal

    2014-01-01

    Negotiation of constricted canals can be a challenge during endodontic treatment. Over the years, several strategies have been presented in order to overcome the difficulties imposed by this anatomical feature. This paper presents three cases using a different protocol from that recommended by the manufacturer of the Protaper System in order to facilitate the negotiation of constricted canals. These cases suggest that the modified protocol shown is able to perform the shaping process with less resistance, reducing the risk of instrument separation and performing an effective process to reach the apical thirds in constricted canals. PMID:24900926

  12. 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.

  13. 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.

  14. Planetary Rings

    NASA Astrophysics Data System (ADS)

    Esposito, Larry

    2014-03-01

    Preface: a personal view of planetary rings; 1. Introduction: the allure of the ringed planets; 2. Studies of planetary rings 1610-2013; 3. Diversity of planetary rings; 4. Individual ring particles and their collisions; 5. Large-scale ring evolution; 6. Moons confine and sculpt rings; 7. Explaining ring phenomena; 8. N-body simulations; 9. Stochastic models; 10. Age and evolution of rings; 11. Saturn's mysterious F ring; 12. Uranus' rings and moons; 13. Neptune's partial rings; 14. Jupiter's ring-moon system after Galileo and New Horizons; 15. Ring photometry; 16. Dusty rings; 17. Concluding remarks; Afterword; Glossary; References; Index.

  15. Hair tourniquet syndrome: revisited

    PubMed Central

    HUSSIN, P.; MAWARDI, M.; MASRAN, M.S.; GANAISAN, P.

    2015-01-01

    Hair tourniquet syndrome is a rare condition. It is an important emergency condition where urgent attention is needed. In this condition, body appendages are strangulated by hair that acts like a tourniquet. A strand or strands of hair act like a circumferential constriction band and subsequently strangulate the body appendages. Commonly affected sites include fingers, toes or even genitals. Failure to identify and release the acute constriction may result in amputation of affected body part. We report two cases of hair tourniquet syndrome of the thumb and toe that were successfully released without complications. PMID:26712259

  16. Planetary Rings

    NASA Astrophysics Data System (ADS)

    Esposito, Larry W.

    2011-07-01

    Preface; 1. Introduction: the allure of ringed planets; 2. Studies of planetary rings 1610-2004; 3. Diversity of planetary rings; 4. Individual ring particles and their collisions; 5. Large-scale ring evolution; 6. Moons confine and sculpt rings; 7. Explaining ring phenomena; 8. N-Body simulations; 9. Stochastic models; 10. Age and evolution of rings; 11. Saturn's mysterious F ring; 12. Neptune's partial rings; 13. Jupiter's ring-moon system after Galileo; 14. Ring photometry; 15. Dusty rings; 16. Cassini observations; 17. Summary: the big questions; Glossary; References; Index.

  17. Cocaine and benzoylecgonine constrict cerebral arteries by different mechanisms.

    PubMed

    Madden, J A; Konkol, R J; Keller, P A; Alvarez, T A

    1995-01-01

    This study was designed to determine possible mechanisms underlying the vasoconstrictor activity of cocaine and its principal metabolite, benzoylecgonine (BE) in cat isolated cerebral arteries. The arteries constricted significantly in response to single doses of cocaine, BE and norepinephrine (NE; (P < 0.05). After 6-OHDA treatment to remove adrenergic nerve endings, NE-induced constrictions were essentially unchanged from those before treatment. Denervated arteries exposed to cocaine dilated significantly (P < 0.05) but those exposed to BE constricted as much as before denervation. Following exposure to prazosin and yohimbine, arterial constrictions to NE and cocaine were significantly reduced from control (P < 0.05) but the BE-induced constriction was unchanged. Ryanodine eliminated the cocaine-induced contraction (P < 0.05) whereas verapamil eliminated the BE response (P < 0.05). These data suggest that while cocaine's vasoconstrictor action may be significantly mediated through adrenergic transmission, BE may act through a mechanism involving calcium (Ca2+) channels. Cocaine levels peak and decline in the body more rapidly than BE levels which can remain detectable for days. This study suggests there may also be different pharmacological mechanisms as well as temporal differences underlying the vasoreactivity of these two substances. Our findings may have implications for pharmacological management of cocaine-induced toxic vascular events. PMID:7869849

  18. Size quantization of Dirac fermions in graphene constrictions

    NASA Astrophysics Data System (ADS)

    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.

    2016-05-01

    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.

  19. Micromagnetic simulations of magnetic nanowires with constrictions by FIB

    NASA Astrophysics Data System (ADS)

    Long, H. H.; Ong, E. T.; Liu, T.; Li, H. L.; Liu, Z. J.; Li, E. P.; Wu, H. Y.; Adeyeye, A. O.

    2006-08-01

    Magnetic structures and magnetization processes of individual Ni nanowires with constrictions are investigated by means of micromagnetic modeling. The physical problem is modeled with the Landau-Lifshitz-Gilbert (LLG) equation, and the fast Fourier transform on multipoles (FFTM) method is employed to speed up the calculation of the demagnetization field. It is demonstrated that the FFTM algorithm is efficient and accurate for studying magnetization transition configuration in nanowire. The new approach is then used to study the switching phenomenon of the nanowire. And the simulation results show that the switching field increases a little with presence of constriction. The investigation of the magnetization processes illustrates the edge domain forms near constriction region for nanowire with diameter=30 nm and vortex domain for 200 nm case.

  20. Fractional charge and spin states in topological insulator constrictions

    NASA Astrophysics Data System (ADS)

    Klinovaja, Jelena; Loss, Daniel

    2015-09-01

    We theoretically investigate the properties of two-dimensional topological insulator constrictions both in the integer and fractional regimes. In the presence of a perpendicular magnetic field, the constriction functions as a spin filter with near-perfect efficiency and can be switched by electric fields only. Domain walls between different topological phases can be created in the constriction as an interface between tunneling, magnetic fields, charge density wave, or electron-electron interaction dominated regions. These domain walls host non-Abelian bound states with fractional charge and spin and result in degenerate ground states with parafermions. If a proximity gap is induced bound states give rise to an exotic Josephson current with 8 π periodicity.

  1. 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. J. Exp. Zool. 9999A:XX-XX, 2016. © 2016 Wiley Periodicals, Inc. PMID:26847931

  2. The brain finger protein gene (ZNF179), a member of the RING finger family, maps within the Smith-Magenis syndrome region at 17p11.2

    SciTech Connect

    Kimura, Toshiyuki; Arakawa, Yoshiki; Inazawa, Johji

    1997-03-31

    Smith-Magenis syndrome (SAIS) is caused by a microdeletion of 17p11.2 and comprises developmental and growth delay, facial abnormalities, unusual behavior and sleep problems. This phenotype may be due to haploinsufficiency of several contiguous genes. The human brain finger protein gene (ZNF179), a member of the RING finger protein family, has been isolated and mapped to l7p11.2. FISH analyses of metaphase or interphase chromosomes of 6 patients with SMS show that ZNF179 was deleted in one of the 2 homologs (17p11.2), indicating a possible association of the defect of this gene with the pathogenesis of SMS. Furthermore, using a prophase FISH ordering system, we sublocalized ZNF179 proximally to LLGL which lies on the critical region for SMS. 27 refs., 2 figs.

  3. A rare combination of amniotic constriction band with osteogenesis imperfecta.

    PubMed

    Shah, Krupa Hitesh; Shah, Hitesh

    2015-01-01

    Amniotic constriction bands and osteogenesis imperfecta are disorders arising from a collagen defect. We report a rare association of amniotic bands with osteogenesis imperfecta in a child. The child was born with multiple amniotic bands involving the right leg, both hands and both feet. Multiple fractures of long bones of lower limbs occurred in childhood due to trivial trauma. Deformities of the femur and tibia due to malunion with osteopenia and blue sclerae were present. The patient was treated with z plasty of constriction band of the right tibia and bisphosphonate for osteogenesis imperfecta. This rare association of both collagen diseases may provide further insight for the pathogenesis of these diseases. PMID:26561227

  4. Constrictive Pericarditis Versus Restrictive Cardiomyopathy?

    PubMed

    Garcia, Mario J

    2016-05-01

    About one-half of the patients with congestive heart failure have preserved left ventricular ejection fraction (HFpEF). Although the etiology of HFpEF is most commonly related to long-standing hypertension and atherosclerosis, a significant number of suspected HFpEF patients have a restrictive cardiomyopathy or chronic pericardial disease. Recognizing these syndromes is important because early diagnosis may lead to instituting specific therapy that may prolong survival, improve quality of life, and/or recognize and treat an underlying systemic disorder. Advances in diagnostic imaging, biomarkers, and genetic testing today allow identification of the specific etiology in most cases. Novel pharmacological, immunologic, and surgical therapies are leading to improved quality of life and survival. PMID:27126534

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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. 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.

  7. 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

  8. [Relaxing and constricting factors derived from vascular endothelium].

    PubMed

    Manso, C

    1991-06-01

    The Author summarizes the factors produced in vascular endothelium in response to different stimuli. The relaxing factor is identified as nitric oxide, a radical, whereas the constricting factor, endothelin, is a peptide. Their actions are related to several situations, both normal and pathologic, still poorly understood. PMID:1931113

  9. 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.

  10. 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…

  11. Poor outcome in radiation-induced constrictive pericarditis

    SciTech Connect

    Karram, T.; Rinkevitch, D.; Markiewicz, W. )

    1993-01-15

    The purpose was to compare the outcome of patients with radiation-induced constrictive pericarditis versus patients with constiction due to another etiology. Twenty patients with constrictive pericarditis were seen during 1975-1986 at a single medical center. Six had radiation-induced constrictive pericarditis (Group A). The etiology was idiopathic in ten subjects and secondary to carcinomatous encasement, chronic renal failure, purulent infection and tuberculosis in one patient each (Group B, N = 14). Meang age was 53.4 [+-] 15.5 years. Extensive pericardiectomy was performed in 3/6 Group A and 13/14 Group B patients. All Group A patients died, 4 weeks - 11 years post-diagnosis (median = 10 months). Two Group A patients died suddenly, one died post-operatively of respiratory failure, another of pneumonia and two of recurrent carcinoma. Thirteen Group B patients are alive (median follow-up = 72 months). The only death in this group was due to metastatic cancer. The poor outcome with radiation-induced constriction is probably multi-factorial. Poor surgical outcome is to be expected in patients with evidence of recurrent tumor, high-dose irradiation, pulmonary fibrosis or associated radiation-induced myocardinal, valvular or coronary damage.

  12. Systemic lupus erythematosus presenting as effuso-constrictive pericarditis.

    PubMed Central

    McMechan, S. R.; McClements, B. M.; McKeown, P. P.; Webb, S. W.; Adgey, A. A.

    1995-01-01

    We describe a 62-year-old woman in whom systemic lupus erythematosus presented as life-threatening effuso-constrictive pericarditis. Surgical drainage of the pericardium was required and the patient made a satisfactory recovery. At six-months follow-up, while taking hydroxychloroquine and a non-steroidal anti-inflammatory agent, she remains well. PMID:8545294

  13. Protective constriction of coronary vein grafts with knitted nitinol

    PubMed Central

    Moodley, Loven; Franz, Thomas; Human, Paul; Wolf, Michael F.; Bezuidenhout, Deon; Scherman, Jacques; Zilla, Peter

    2013-01-01

    OBJECTIVES Different flow patterns and shear forces were shown to cause significantly more luminal narrowing and neointimal tissue proliferation in coronary than in infrainguinal vein grafts. As constrictive external mesh support of vein grafts led to the complete suppression of intimal hyperplasia (IH) in infrainguinal grafts, we investigated whether mesh constriction is equally effective in the coronary position. METHODS Eighteen senescent Chacma baboons (28.8 ± 3.6 kg) received aorto-coronary bypass grafts to the left anterior descending artery (LAD). Three groups of saphenous vein grafts were compared: untreated controls (CO); fibrin sealant-sprayed controls (CO + FS) and nitinol mesh-constricted grafts (ME + FS). Meshes consisted of pulse-compliant, knitted nitinol (eight needles; 50 μm wire thickness; 3.4 mm resting inner diameter, ID) spray attached to the vein grafts with FS. After 180 days of implantation, luminal dimensions and IH were analysed using post-explant angiography and macroscopic and histological image analysis. RESULTS At implantation, the calibre mismatch between control grafts and the LAD expressed as cross-sectional quotient (Qc) was pronounced [Qc = 0.21 ± 0.07 (CO) and 0.18 ± 0.05 (CO + FS)]. Mesh constriction resulted in a 29 ± 7% reduction of the outer diameter of the vein grafts from 5.23 ± 0.51 to 3.68 ± 0 mm, significantly reducing the calibre discrepancy to a Qc of 0.41 ± 0.17 (P < 0.02). After 6 months of implantation, explant angiography showed distinct luminal irregularities in control grafts (ID difference between widest and narrowest segment 74 ± 45%), while diameter variations were mild in mesh-constricted grafts. In all control grafts, thick neointimal tissue was present [600 ± 63 μm (CO); 627 ± 204 μm (CO + FS)] as opposed to thin, eccentric layers of 249 ± 83 μm in mesh-constricted grafts (ME + FS; P < 0.002). The total wall thickness had increased by 363 ± 39% (P < 0.00001) in CO and 312 ± 61% (P < 0

  14. Nanoplough-constrictions on thin YBCO films made with atomic force microscopy.

    PubMed

    Elkaseh, A A O; Büttner, U; Meincken, M; Hardie, G L; Srinivasu, V V; Perold, W J

    2007-09-01

    Utilizing atomic force microscope (AFM) with a diamond tip, we were able to successfully plough nano-constrictions on epitaxially grown YBa2Cu3O(7-x) thin films deposited on MgO substrates. The thickness, width, and length of the obtained constrictions were in the range of a few 100 nm. Furthermore, we managed to produce a new S-type constriction, of which the dimensions are easier to control than for conventional constrictions. PMID:18019174

  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.]. PMID:27183556

  16. 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.

  17. [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

  18. 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.

  19. Constrictive Bronchiolitis in Soldiers Returning from Iraq and Afghanistan

    PubMed Central

    King, Matthew S.; Eisenberg, Rosana; Newman, John H.; Tolle, James J.; Harrell, Frank E.; Nian, Hui; Ninan, Mathew; Lambright, Eric S.; Sheller, James R.; Johnson, Joyce E.; Miller, Robert F.

    2012-01-01

    Background In this descriptive case series, 80 soldiers from Fort Campbell, Kentucky, with inhalational exposures during service in Iraq and Afghanistan were evaluated for dyspnea on exertion that prevented them from meeting the U.S. Army's standards for physical fitness. Methods The soldiers underwent extensive evaluation of their medical and exposure history, physical examination, pulmonary-function testing, and high-resolution computed tomography (CT). A total of 49 soldiers underwent thoracoscopic lung biopsy after noninvasive evaluation did not provide an explanation for their symptoms. Data on cardiopulmonary-exercise and pulmonary-function testing were compared with data obtained from historical military control subjects. Results Among the soldiers who were referred for evaluation, a history of inhalational exposure to a 2003 sulfur-mine fire in Iraq was common but not universal. Of the 49 soldiers who underwent lung biopsy, all biopsy samples were abnormal, with 38 soldiers having changes that were diagnostic of constrictive bronchiolitis. In the remaining 11 soldiers, diagnoses other than constrictive bronchiolitis that could explain the presenting dyspnea were established. All soldiers with constrictive bronchiolitis had normal results on chest radiography, but about one quarter were found to have mosaic air trapping or centrilobular nodules on chest CT. The results of pulmonary-function and cardiopulmonary-exercise testing were generally within normal population limits but were inferior to those of the military control subjects. Conclusions In 49 previously healthy soldiers with unexplained exertional dyspnea and diminished exercise tolerance after deployment, an analysis of biopsy samples showed diffuse constrictive bronchiolitis, which was possibly associated with inhalational exposure, in 38 soldiers. PMID:21774710

  20. Splenic constriction during isometric handgrip exercise in humans.

    PubMed

    Frances, Maria F; Dujic, Zeljko; Shoemaker, J Kevin

    2008-10-01

    During the first minute of a moderate-intensity isometric handgrip (HG) exercise, there is an increase in stroke volume and cardiac output that occurs without any change in systemic vascular conductance. Although the mechanism of increased venous return is not yet known, current focus has been placed on the constriction of visceral organs. The human spleen represents a compliant organ with high perfusion that constricts during the rather severe stresses of maximal exercise, a diving reflex, or prolonged apnea. This study tested the hypothesis that spleen constriction occurs during isometric HG exercise. Eight participants performed a 1 min isometric HG test at 40% maximum voluntary contraction. Splenic length and width were measured (with ultrasound imaging) after 1 min of exercise, and volume was calculated. To investigate the reflex specificity of this response, spleen dimensions were also measured during 4 min of lower-body negative pressure (LBNP; -20 mm Hg). To test the additional impact of altered breathing and intra-abdominal pressures during the HG, measures were also taken during Valsalva's manoeuvre (VM) at 30 mm Hg. Compared with baseline, both length and width of the spleen were reduced by 0.20 to 0.55 cm (or 4.44%-6.09%; p < 0.05) during each test. This resulted in relative reductions in splenic volume of 13 +/- 1% (HG), 9% +/- 7% (LBNP) and 18% +/- 7% (VM) (p < 0.05; all mean +/- SD). It was concluded that the spleen can constrict during the first minute of isometric HG exercise. PMID:18923575

  1. 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.

  2. 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

  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. 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.

  5. Size quantization of Dirac fermions in graphene constrictions.

    PubMed

    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 × 10(6) 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

  6. 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.

  7. Saturn's rings

    NASA Technical Reports Server (NTRS)

    2000-01-01

    When seen from the unlit side, the rings of Saturn present a much different appearance from that familiar to telescopic observers. Relatively opaque areas like the B Ring turn black, while lightly populated zones, such as the C Ring and the Cassini Division, prove to excellent diffuse transmitters of sunlight. The A Ring, with intermediate opacity, is at an intermediate level of brightness.

  8. Purely electrical detection of a skyrmion in constricted geometry

    NASA Astrophysics Data System (ADS)

    Hamamoto, Keita; Ezawa, Motohiko; Nagaosa, Naoto

    2016-03-01

    How to detect the skyrmion position is a crucial problem in future skyrmionics since it corresponds to the reading process of information. We propose a method to detect the skyrmion position purely electrically by measuring the Hall conductance in a constricted geometry. The Hall conductance becomes maximum when a skyrmion is at the lead position. It is possible to detect the skyrmion position even at room temperature. We find an optimized width of the sample determined by the skyrmion radius. We also investigate the effects of elastic and inelastic scatterings, and finite temperature. Our results will be a basis of future skyrmion electronics.

  9. 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.

  10. 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

  11. 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

  12. Mechanical response of red blood cells entering a constriction.

    PubMed

    Zeng, Nancy F; Ristenpart, William D

    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 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

  13. 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.

  14. 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.

  15. 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 ...

  16. 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.

  17. Actomyosin ring driven cytokinesis in budding yeast.

    PubMed

    Meitinger, Franz; Palani, Saravanan

    2016-05-01

    Cytokinesis is the final process in the cell cycle that physically divides one cell into two. In budding yeast, cytokinesis is driven by a contractile actomyosin ring (AMR) and the simultaneous formation of a primary septum, which serves as template for cell wall deposition. AMR assembly, constriction, primary septum formation and cell wall deposition are successive processes and tightly coupled to cell cycle progression to ensure the correct distribution of genetic material and cell organelles among the two rising cells prior to cell division. The role of the AMR in cytokinesis and the molecular mechanisms that drive AMR constriction and septation are the focus of current research. This review summarizes the recent progresses in our understanding of how budding yeast cells orchestrate the multitude of molecular mechanisms that control AMR driven cytokinesis in a spatio-temporal manner to achieve an error free cell division. PMID:26845196

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

    PubMed Central

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

    2015-01-01

    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

  19. Dietary cholesterol protects against alcohol-induced cerebral artery constriction

    PubMed Central

    Bukiya, Anna; Dopico, Alex; Leffler, Charles; Fedinec, Alexander

    2014-01-01

    Background Binge drinking represents the major form of excessive alcohol (EtOH) consumption in the US. Episodic (such as binge) drinking results in blood alcohol levels (BAL) of 18–80 mM, and leads to alcohol-induced cerebral artery constriction (AICAC). AICAC was shown to arise from EtOH-induced inhibition of large-conductance, calcium/voltage-gated potassium (BK) channels in the vascular smooth muscle. Factors that modulate BK channel-mediated AICAC remain largely unknown. Methods Male Sprague-Dawley rats were placed on high-cholesterol (2% of cholesterol) diet for 18–23 weeks. Their littermates were placed on control iso-caloric diet. AICAC was evaluated both in vivo and in vitro, by means of pial arteriole diameter monitoring through a closed cranial window and diameter measurements of isolated, pressurized cerebral arteries. Cholesterol level in the cerebral artery tissue was manipulated by methyl-β-cyclodextrin to reverse dietary-induced accumulation of cholesterol. BK channel surface presence on the plasma membrane of cerebral artery myocytes was evaluated by immunofluorescence staining. BK channel function in pressurized cerebral artery was assessed using selective BK channel blocker paxilline. Results Within 5 minutes of 50 mM EtOH injection into carotid artery in vivo, arteriole diameter decreased by 20% in control group. Pial arteriole constriction was significantly reduced in rats on high-cholesterol diet, resulting in only 10% reduction of diameter. BAL in both groups, however, remained the same. Significant reduction of AICAC in group on high-cholesterol diet compared to control was also observed after middle cerebral artery dissection and in vitro pressurization at 60 mmHg, this reduction remaining after endothelium removal. Cholesterol level in de-endothelialized cerebral arteries was significantly increased in rats on high-cholesterol diet. Removal of excessive cholesterol content restored AICAC to the level, observed in cerebral arteries of

  20. Amniotic band syndrom at Bobo Dioulasso university teaching hospital (Burkina-Faso): about two cases

    PubMed Central

    Zaré, Cyprien; Traoré, Ibrahim Alain; Dakouré, Patrick Wendpuoiré Hamed; Gandéma, Salif; Sano, Bakary Gustave; Bénao, Lazard Bouma; Belemlilga, Hermann; Yabré, Nassirou

    2015-01-01

    Amniotic band syndrome is a rare congenital disorder. The authors report the first cases documented at Souro Sanou University Hospital in Bobo-Dioulasso (CHUSS) in 2 male new borns. The malformations found at birth, were worn only on limbs and were in the form of skin furrow necking with a major lymphedema downstream. In both cases, the constriction furrow at member pelvic was associated with a club foot and a pseudosyndactyly in one case. Surgical treatment consisted of a section of the constrictor ring and a Z-plasty. The functional outcome was satisfactory with the acquisition of a plantar support for both children. Through these two observations, epidemiological, diagnostic, and particularities of the management of this condition are discussed in the Burkina-Faso. PMID:26918082

  1. Modelling apical constriction in epithelia using elastic shell theory.

    PubMed

    Jones, Gareth Wyn; Chapman, S Jonathan

    2010-06-01

    Apical constriction is one of the fundamental mechanisms by which embryonic tissue is deformed, giving rise to the shape and form of the fully-developed organism. The mechanism involves a contraction of fibres embedded in the apical side of epithelial tissues, leading to an invagination or folding of the cell sheet. In this article the phenomenon is modelled mechanically by describing the epithelial sheet as an elastic shell, which contains a surface representing the continuous mesh formed from the embedded fibres. Allowing this mesh to contract, an enhanced shell theory is developed in which the stiffness and bending tensors of the shell are modified to include the fibres' stiffness, and in which the active effects of the contraction appear as body forces in the shell equilibrium equations. Numerical examples are presented at the end, including the bending of a plate and a cylindrical shell (modelling neurulation) and the invagination of a spherical shell (modelling simple gastrulation). PMID:19859751

  2. 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

  3. [Surgical treatment of 2 cases of irradiation induced constrictive pericarditis].

    PubMed

    Osawa, H; Takahashi, W; Yoshii, S; Hosaka, S; Kaga, S; Fukuda, N; Samuel, A; Nagasaka, S; Miyauchi, Y; Tada, Y

    1999-11-01

    A 72-years-old man underwent radiation therapy (62 Gy) for esophageal carcinoma. Twelve months later, symptoms of heart failure such as syncope, cough and hepatomegaly manifested. On catheter study, a dip and plateau pattern of right ventricular pressure curve was evident. Pericardiectomy without extracorporeal circulation was performed. Operative findings and pathological results were compatible with radiation-induced constrictive pericarditis. He recovered from the heart failure, and has been doing well 3 months after the surgery. A 54-years-old man underwent thymectomy for malignant thymoma. He underwent a radiation therapy (52 Gy) postoperatively. After 12 months from the irradiation, syncope and dyspnea manifested. On catheter study, a dip and plateau pattern of right ventricular pressure curve was observed. Pericardiectomy with extracorporeal circulation was performed. He recovered from the heart failure after pericardiectomy, however he died of radiation-induced pneumonitis 6 months later. PMID:10554496

  4. [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. PMID:24701812

  5. 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

  6. 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.

  7. Transit Characteristics of a Neutrophil Passing through Two Moderate Constrictions in a Cylindrical Capillary Vessel

    NASA Astrophysics Data System (ADS)

    Shirai, Atsushi; Fujita, Ryo; Hayase, Toshiyuki

    Neutrophils must flow through the pulmonary capillary network in a deformed shape because pulmonary capillaries are closely interconnected, and deformed neutrophils take about 15 s to 1 min to return to their resting spherical shape. In this paper, flow of a neutrophil through two moderate constrictions in a pipeline is numerically investigated, focusing on the effect of cell deformation on the cell's transit time through the constrictions. Changing sizes and positions of the constrictions, we found that the maximum cell radius at the entrance of the constriction and the throat radius of the constriction are the dominant factors in predicting the cell's transit time through the constriction. When the difference between these two radii is relatively large, steeper constriction (smaller radius of curvature) increases the transit time, but this tendency is reversed when the difference is small. Cells traverse the constriction without delay when the maximum cell radius and throat radius are comparable. Finally, we present a simple mathematical model for the transit time.

  8. Stenosis map for volume visualization of constricted tubular structures: Application to coronary artery stenosis.

    PubMed

    Yun, Jihye; Kim, Yeo Koon; Chun, Eun Ju; Shin, Yeong-Gil; Lee, Jeongjin; Kim, Bohyoung

    2016-02-01

    Although direct volume rendering (DVR) has become a commodity, effective rendering of interesting features is still a challenge. In one of active DVR application fields, the medicine, radiologists have used DVR for the diagnosis of lesions or diseases that should be visualized distinguishably from other surrounding anatomical structures. One of most frequent and important radiologic tasks is the detection of lesions, usually constrictions, in complex tubular structures. In this paper, we propose a 3D spatial field for the effective visualization of constricted tubular structures, called as a stenosis map which stores the degree of constriction at each voxel. Constrictions within tubular structures are quantified by using newly proposed measures (i.e. line similarity measure and constriction measure) based on the localized structure analysis, and classified with a proposed transfer function mapping the degree of constriction to color and opacity. We show the application results of our method to the visualization of coronary artery stenoses. We present performance evaluations using twenty eight clinical datasets, demonstrating high accuracy and efficacy of our proposed method. The ability of our method to saliently visualize the constrictions within tubular structures and interactively adjust the visual appearance of the constrictions proves to deliver a substantial aid in radiologic practice. PMID:26608866

  9. Planetary Rings

    NASA Astrophysics Data System (ADS)

    Gordon, M. K.; Araki, S.; Black, G. J.; Bosh, A. S.; Brahic, A.; Brooks, S. M.; Charnoz, S.; Colwell, J. E.; Cuzzi, J. N.; Dones, L.; Durisen, R. H.; Esposito, L. W.; Ferrari, C.; Festou, M.; French, R. G.; Giuliatti-Winter, S. M.; Graps, A. L.; Hamilton, D. P.; Horanyi, M.; Karjalainen, R. M.; Krivov, A. V.; Krueger, H.; Larson, S. M.; Levison, H. F.; Lewis, M. C.; Lissauer, J. J.; Murray, C. D.; Namouni, F.; Nicholson, P. D.; Olkin, C. B.; Poulet, F.; Rappaport, N. J.; Salo, H. J.; Schmidt, J.; Showalter, M. R.; Spahn, F.; Spilker, L. J.; Srama, R.; Stewart, G. R.; Yanamandra-Fisher, P.

    2002-08-01

    The past two decades have witnessed dramatic changes in our view and understanding of planetary rings. We now know that each of the giant planets in the Solar System possesses a complex and unique ring system. Recent studies have identified complex gravitational interactions between the rings and their retinues of attendant satellites. Among the four known ring systems, we see elegant examples of Lindblad and corotation resonances (first invoked in the context of galactic disks), electromagnetic resonances, spiral density waves and bending waves, narrow ringlets which exhibit internal modes due to collective instabilities, sharp-edged gaps maintained via tidal torques from embedded moonlets, and tenuous dust belts created by meteoroid impact onto, or collisions between, parent bodies. Yet, as far as we have come, our understanding is far from complete. The fundamental questions confronting ring scientists at the beginning of the twenty-first century are those regarding the origin, age and evolution of the various ring systems, in the broadest context. Understanding the origin and age requires us to know the current ring properties, and to understand the dominant evolutionary processes and how they influence ring properties. Here we discuss a prioritized list of the key questions, the answers to which would provide the greatest improvement in our understanding of planetary rings. We then outline the initiatives, missions, and other supporting activities needed to address those questions, and recommend priorities for the coming decade in planetary ring science.

  10. Thalidomide in Treating Patients With Myelodysplastic Syndrome

    ClinicalTrials.gov

    2013-01-23

    Chronic Myelomonocytic Leukemia; de Novo Myelodysplastic Syndromes; Previously Treated Myelodysplastic Syndromes; Refractory Anemia; Refractory Anemia With Excess Blasts; Refractory Anemia With Excess Blasts in Transformation; Refractory Anemia With Ringed Sideroblasts; Secondary Myelodysplastic Syndromes

  11. 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.

  12. 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

  13. Re-examining Archie's law: Conductance description by tortuosity and constriction.

    PubMed

    Berg, Carl Fredrik

    2012-10-01

    In this article we investigate the electrical conductance of an insulating porous medium (e.g., a sedimentary rock) filled with an electrolyte (e.g., brine), usually described using the Archie cementation exponent. We show how the electrical conductance depends on changes in the drift velocity and the length of the electric field lines, in addition to the porosity and the conductance of the electrolyte. We characterize the length of the electric field lines by a tortuosity and the changes in drift velocity by a constriction factor. Both the tortuosity and the constriction factor are descriptors of the pore microstructure. We define a conductance reduction factor to measure the local contributions of the pore microstructure to the global conductance. It is shown that the global conductance reduction factor is the product of the tortuosity squared divided by the constriction factor, thereby proving that the combined effect of tortuosity and constriction, in addition to the porosity and conductance of the electrolyte, fully describes the effective electrical conductance of a porous medium. We show that our tortuosity, constriction factor, and conductance reduction factor reproduce the electrical conductance for idealized porous media. They are also applied to Bentheimer sandstone, where we describe a microstructure-related correlation between porosity and conductivity using both the global conductance reduction factor and the distinct contributions from tortuosity and constriction. Overall, this work shows how the empirical Archie cementation exponent can be substituted by more descriptive, physical parameters, either by the global conductance reduction factor or by tortuosity and constriction. PMID:23214684

  14. 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

  15. Differentiation Therapy With Decitabine in Treating Patients With Myelodysplastic Syndrome

    ClinicalTrials.gov

    2013-02-25

    Chronic Myelomonocytic Leukemia; de Novo Myelodysplastic Syndromes; Myelodysplastic Syndromes; Refractory Anemia; Refractory Anemia With Excess Blasts; Refractory Anemia With Ringed Sideroblasts; Refractory Cytopenia With Multilineage Dysplasia; Thrombocytopenia

  16. Removal of a Penile Constriction Device with a Large Orthopedic Pin Cutter

    PubMed Central

    Wenzler, David; Fischer, Melissa

    2014-01-01

    Penile strangulation is an infrequent clinical condition that has widely been reported. It usually results following placement of a constriction device to enhance sexual stimulation. Early treatment is essential to avoid potential complications, including ischemic necrosis and autoamputation. We describe the use of a Large Orthopedic Pin Cutter to remove a metal penile constriction device in the Emergency Department (ED). This case report describes the relatively safe technique of using an instrument available in many hospitals that can be added to the physician's arsenal in the removal of metal constriction devices. PMID:24707434

  17. 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)].

  18. 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.

  19. 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

  20. Current-induced skyrmion dynamics in constricted geometries.

    PubMed

    Iwasaki, Junichi; Mochizuki, Masahito; Nagaosa, Naoto

    2013-10-01

    Magnetic skyrmions--vortex-like swirling spin structures with a quantized topological number that are observed in chiral magnets--are appealing for potential applications in spintronics because it is possible to control their motion with ultralow current density. To realize skyrmion-based spintronic devices, it is essential to understand skyrmion motions in confined geometries. Here we show by micromagnetic simulations that the current-induced motion of skyrmions in the presence of geometrical boundaries is very different from that in an infinite plane. In a channel of finite width, transverse confinement results in steady-state characteristics of the skyrmion velocity as a function of current that are similar to those of domain walls in ferromagnets, whereas the transient behaviour depends on the initial distance of the skyrmion from the boundary. Furthermore, we show that a single skyrmion can be created by an electric current in a simple constricted geometry comprising a plate-shaped specimen of suitable size and geometry. These findings could guide the design of skyrmion-based devices in which skyrmions are used as information carriers. PMID:24013132

  1. Prenatal diagnosis of amniotic band syndrome

    PubMed Central

    Padmanabhan, Laxmi Devi; Hamza, Zareena V; Thampi, Madhavan Venugopalan; Nampoothiri, Sheela

    2016-01-01

    Amniotic band can cause a broad spectrum of anomalies ranging from simple band constrictions to major craniofacial and visceral defects. It can cause significant neonatal morbidity. Accurate diagnosis will help in the management of the present pregnancy and in counseling with regard to future pregnancies. Here we report three cases of amniotic band syndrome detected in the prenatal period. PMID:27081225

  2. Ring Chromosome 9 and Chromosome 9p Deletion Syndrome in a Patient Associated with Developmental Delay: A Case Report and Review of the Literature.

    PubMed

    Sivasankaran, Aswini; Kanakavalli, Murthy K; Anuradha, Deenadayalu; Samuel, Chandra R; Kandukuri, Lakshmi R

    2016-01-01

    Ring chromosomes have been described for all human chromosomes and are typically associated with physical and/or mental abnormalities resulting from a deletion of the terminal ends of both chromosome arms. This report describes the presence of a ring chromosome 9 in a 2-year-old male child associated with developmental delay. The proband manifested a severe phenotype comprising facial dysmorphism, congenital heart defects, and seizures. The child also exhibited multiple cell lines with mosaic patterns of double rings, a dicentric ring and loss of the ring associated with mitotic instability and dynamic tissue-specific mosaicism. His karyotype was 46,XY,r(9)(p22q34)[89]/46,XY,dic r(9; 9)(p22q34;p22q34)[6]/45, XY,-9[4]/47,XY,r(9),+r(9)[1]. However, the karyotypes of his parents and elder brother were normal. FISH using mBAND probe and subtelomeric probes specific for p and q arms for chromosome 9 showed no deletion in any of the regions. Chromosomal microarray analysis led to the identification of a heterozygous deletion of 15.7 Mb from 9p22.3 to 9p24.3. The probable role of the deleted genes in the manifestation of the phenotype of the proband is discussed. PMID:27222354

  3. The thermal constriction resistance of a strip contact spot on a thin film

    NASA Astrophysics Data System (ADS)

    Yang, Fuqian; Prasad, Vish; Kao, Imin

    1999-04-01

    The thermal constriction resistance of a strip contact spot on a layer of material is analysed for the heat-flux specified boundary condition on the contact zone. Using Green's function, the solution of heat-conduction problems is reduced to a new type of hypersingular integral equations with a hyperbolic function kernel. The hypersingular integral equations are solved analytically, which provides closed-form solutions for the thermal constriction resistance. For a thin film and isoflux conditions over the contact zone, the thermal constriction resistance is proportional to the ratio of the film thickness to the contact width when the other side of the film is considered isothermal, whereas it is inversely proportional to this ratio for an adiabatic back. Such a large variation and reversal in trend reveals the possibility of using this method for the measurement of film thicknesses by measuring the thermal constriction resistance.

  4. Congenital Erythropoietic Porphyria With Calcific Constrictive Pericarditis: A Case Report and Brief Review of Literature.

    PubMed

    Chowdhury, Ujjwal K; Patel, Kartik; Seth, Sandeep; Ray, Ruma; Jagia, Priya; Sahu, Manoj

    2015-10-01

    An 18-year-old boy with congenital erythropoietic porphyria and calcific constrictive pericarditis underwent total pericardiectomy. The cause of pericardial calcification could be deposition of porphyrins in the pericardium. Surgical importance of this rare condition is highlighted. PMID:26467880

  5. 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.

  6. 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

  7. [An operative case of chronic constrictive pericarditis with silicosis and lumbar caries].

    PubMed

    Ohnishi, Y; Katada, H; Kasuga, H; Sawaki, M; Narita, N; Kushibe, K; Kawachi, K; Kitamura, S; Masuhara, K

    1990-03-01

    We reported a case of chronic constrictive pericarditis complicated with silicosis and lumbar caries, who was improved by the operation. The patient was a 65 year old man whose past occupation was a mason. He was admitted to our hospital with chronic heart failure on March, 1986. Atypical silicosis was diagnosed from the occupational history and the histopathological silicotic changes in mediastinal lymph nodes and fibrosis of alveolar wall. The diagnosis of chronic constrictive pericarditis was made from chest roentgenogram and intracardiac catheterization. The symptoms of chronic constrictive pericarditis was improved by the pericardial resection. The exact pathogenesis of the chronic constrictive pericarditis could not be identified from the histology of pericardial tissue, but tuberculosis was suspected because of the past history of tuberculous pleurisy and the recurrence of lumbar caries. PMID:2352410

  8. Differentiation of constrictive pericarditis from restrictive cardiomyopathy: The case for high-resolution dynamic tomographic imaging

    SciTech Connect

    Weiss, R.M.; Otoadese, T.; Oren, R.M.

    1995-12-31

    The syndrome of constrictive pericarditis (CP) presents a diagnostic challenge to the clinician. This study was undertaken to determine whether cine computed tomography (CT), a cardiac imaging technique with excellent temporal and spatial resolution, can reliably demonstrate the unique abnormalities of pericardial anatomy and ventricular physiology present in patients with this condition. A second goal of this study was to determine whether the presence of diseased thickened pericardium, but itself, imparts cardiac impairment due to abnormalities of ventricular diastolic function. Twelve patients with CP suspected clinically, in whom invasive hemodynamic study was consistent with the diagnosis of CP, underwent cine CT. They were subdivided into Group 1 (CP, N = 5) and Group 2 (No CP, N = 7) based on histopathologic evaluation of tissue obtained at the time of surgery or autopsy. A third group consisted of asymptomatic patients with incidentally discovered thickened pericardium at the time of cine CT scanning: Group 3 (ThP, N = 7). Group 4 (Nl, N = 7) consisted of healthy volunteer subjects. Pericardial thickness measurements with cine CT clearly distinguished Group 1 (mean = 10 {+-} 2 mm) from Group 2 (mean = 2 {+-} 1 mm), with diagnostic accuracy of 100% compared to histopathological findings. In addition, patients in Group 1 had significantly more brisk early diastolic filling of both left and right ventricles than those in Group 2, which clearly distinguished all patients with and from all patients without CP. Patients in Group 3 had pericardial thicknesses similar to those in Group 1 (mean = 9 {+-} 1 mm, p = NS), but had patterns of diastolic ventricular filling that were nearly identical to Group 4 (NI).

  9. 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. PMID:23824575

  10. Storage Rings

    SciTech Connect

    Fischer, W.

    2011-01-01

    Storage rings are circular machines that store particle beams at a constant energy. Beams are stored in rings without acceleration for a number of reasons (Tab. 1). Storage rings are used in high-energy, nuclear, atomic, and molecular physics, as well as for experiments in chemistry, material and life sciences. Parameters for storage rings such as particle species, energy, beam intensity, beam size, and store time vary widely depending on the application. The beam must be injected into a storage ring but may not be extracted (Fig. 1). Accelerator rings such as synchrotrons are used as storage rings before and after acceleration. Particles stored in rings include electrons and positrons; muons; protons and anti-protons; neutrons; light and heavy, positive and negative, atomic ions of various charge states; molecular and cluster ions, and neutral polar molecules. Spin polarized beams of electrons, positrons, and protons were stored. The kinetic energy of the stored particles ranges from 10{sup -6} eV to 3.5 x 10{sup 12} eV (LHC, 7 x 10{sup 12} eV planned), the number of stored particles from one (ESR) to 1015 (ISR). To store beam in rings requires bending (dipoles) and transverse focusing (quadrupoles). Higher order multipoles are used to correct chromatic aberrations, to suppress instabilities, and to compensate for nonlinear field errors of dipoles and quadrupoles. Magnetic multipole functions can be combined in magnets. Beams are stored bunched with radio frequency systems, and unbunched. The magnetic lattice and radio frequency system are designed to ensure the stability of transverse and longitudinal motion. New technologies allow for better storage rings. With strong focusing the beam pipe dimensions became much smaller than previously possible. For a given circumference superconducting magnets make higher energies possible, and superconducting radio frequency systems allow for efficient replenishment of synchrotron radiation losses of large current electron or

  11. The role of mast cells in citric acid-induced airway constriction and cough.

    PubMed

    Lai, Yih-Loong; Wu, Li-Ling; Lin, Tai-Yin; Lin, Chien-He

    2009-11-30

    Inhalation of citric acid (CA) causes airway constriction and coughing. To investigate the role of mast cells in CA-induced airway constriction and cough, three experiments using guinea pigs were carried out. In the first experiment, we used compound 48/80 to deplete mast cells, cromolyn sodium to stabilize mast cells, MK-886 to inhibit synthesis of leukotrienes, pyrilamine to antagonize histamine H1 receptor, methysergide to antagonize serotonin receptor, and indomethacin to inhibit cyclooxygenase. In the second experiment, compound 48/80-pretreated animals were divided into 2 parts; the first one was used to test the role of exogenous leukotriene (LT) C4, while the second one to test the role of exogenous histamine. Decreases in respiratory compliance (Crs) and forced expiratory volume in 0.1 sec (FEV0.1) were used as indicators for airway constriction in anesthetized guinea pigs. CA-induced cough was recorded for 12 min using a barometric body plethysmograph in conscious animals. In the third experiment, the activation of mast cells upon CA inhalation was investigated by determining lung tissue or arterial plasma histamine concentration in animals. Exposure to CA induced marked airway constriction and increase in cough number. Compound 48/80, cromolyn sodium, MK-886 and pyrilamine, but not indomethacin or methysergide, significantly attenuated CA-induced airway constriction and cough. Injection of LTC4 or histamine caused a significant increase in CA-induced airway constriction and cough in compound 48/80-pretreated animals. In addition, CA inhalation caused significant increase in lung tissue and plasma histamine concentrations, which were blocked by compound 48/80 pretreatment. These results suggest that mast cells play an important role in CA aerosol inhalation-induced airway constriction and cough via perhaps mediators including LTs and histamine. PMID:20359123

  12. 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.

  13. Ring Galaxies

    NASA Astrophysics Data System (ADS)

    Dennefeld, M.; Materne, J.

    1980-09-01

    Among the 338 exotic, intriguing and/or fascinating objects contained in Arp's catalogue of peculiar galaxies, two, Arp 146 and 147, are calling special attention as a presumably separate class of objects displaying closed rings with almost empty interior. It is difficult to find out when, historically speaking, attention was called first to this type of object as a peculiar class, but certainly ga1axies with rings were widely found and recognized in the early sixties, ul}der others by Vorontsov-Velyaminov (1960), Sandage (1961) in the Hubble Atlas or de Vaucouleurs (1964) in the first reference catalogue of ga1axies. The most recent estimates by Arp and Madore (1977) from a search on about 200 Schmidt plates covering 7,000 square degrees give 3.6 per cent of ring galaxies among 2,784 peculiar galaxies found. However, despite the mythological perfection associated with a circle, some ordering is necessary before trying to understand the nature of such objects. This is particularly true because a large fraction of those galaxies with rings are probably normal spiral galaxies of type RS or S(r) as defined by de Vaucouleurs, where the spiral arms are simply "closing the circle". A good example of such "ordinary" galaxy is NGC 3081 in the Hubble Atlas .

  14. Lenalidomide in Treating Young Patients With Relapsed or Refractory Solid Tumors or Myelodysplastic Syndromes

    ClinicalTrials.gov

    2014-06-10

    Childhood Myelodysplastic Syndromes; de Novo Myelodysplastic Syndromes; Previously Treated Myelodysplastic Syndromes; Refractory Anemia; Refractory Anemia With Excess Blasts; Refractory Anemia With Ringed Sideroblasts; Refractory Cytopenia With Multilineage Dysplasia; Secondary Myelodysplastic Syndromes; Unspecified Childhood Solid Tumor, Protocol Specific

  15. 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.

  16. 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

  17. Baclofen reversed thermal place preference in rats with chronic constriction injury.

    PubMed

    Salte, K; Lea, G; Franek, M; Vaculin, S

    2016-06-20

    Chronic constriction injury to the sciatic nerve was used as an animal model of neuropathic pain. Instead of frequently used reflex-based tests we used an operant thermal place preference test to evaluate signs of neuropathic pain and the effect of baclofen administration in rats with neuropathy. Chronic constriction injury was induced by four loose ligations of the sciatic nerve. Thermal place preference (45 °C vs. 22 °C and 45 °C vs. 11 °C) was measured after the ligation and after the administration of baclofen in sham and experimental rats. Rats with the chronic constriction injury spent significantly less time on the colder plate compared to sham operated animals at the combination 45 °C vs. 11 °C. After administration of baclofen (10 mg/kg s.c.), the aversion to the colder plate in rats with chronic constriction injury disappeared. At the combination 45 °C vs. 22 °C, no difference in time spent on colder and/or warmer plate was found between sham and experimental animals. These findings show the importance of cold allodynia evaluation in rats with chronic constriction injury and the effectiveness of baclofen in this neuropathic pain model. PMID:26447518

  18. 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

  19. Mechanical modelling of confined cell migration across constricted-curved micro-channels.

    PubMed

    Allena, R

    2014-09-01

    Confined migration is a crucial phenomenon during embryogenesis, immune response and cancer. Here, a two-dimensional finite element model of a HeLa cell migrating across constricted-curved micro-channels is proposed. The cell is modelled as a continuum with embedded cytoplasm and nucleus, which are described by standard Maxwell viscoelastic models. The decomposition of the deformation gradient is employed to define the cyclic active strains of protrusion and contraction, which are synchronized with the adhesion forces between the cell and the substrate. The micro-channels are represented by two rigid walls and exert an additional viscous force on the cell boundaries. Five configurations have been tested: 1) top constriction, 2) top-bottom constriction, 3) shifted top-bottom constriction, 4) embedded obstacle and 5) bending micro-channel. Additionally, for the first four micro-channels both sub-cellular and sub-nuclear constrictions have been obtained, while for the fifth micro-channel three types of bending have been investigated ('curved', 'sharp' and 'sharper'). For each configuration, several parameters such as the cell behaviour, the covered distance, the migration velocity, the ratio between the cell and the nucleus area as well as the cell-substrate and cell-channel surfaces forces have been evaluated. The results show once more the fundamental role played by mechanics of both the cell and the environment. PMID:25831860

  20. 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

  1. Metric Analysis of the Hard Palate in Children with Down Syndrome--A Comparative Study

    ERIC Educational Resources Information Center

    Bhagyalakshmi, Gopalan; Renukarya, Annappa Jai; Rajangam, Sayee

    2007-01-01

    The hard palate is viewed as playing an important role in the passive articulation of speech. Its probable role in the defective articulation of speech in individuals with Down syndrome has been examined in the present study. In individuals with Down syndrome, the hard palate is highly arched, constricted, and narrow and stair type with malformed…

  2. Effect of Strain Rate on the Deformation of Red Blood Cells Entering a Constriction

    NASA Astrophysics Data System (ADS)

    Mancuso, Jordan; Ristenpart, William

    2015-11-01

    Although much work has investigated the stretching behavior of RBCs in shear flows, relatively little work has examined the deformation that occurs in the physiologically important extensional flow at the entrance to a constriction. In particular, there is currently no analytical model to predict the extent of deformation as a function of the strain rate in the constriction entrance. Here we experimentally elucidate the relationship between strain rate and the dynamic stretching behavior of RBCs as they enter a microfluidic constriction. We systematically varied the flow rate and the microchannel geometry to vary the strain rate, and we measured the resulting RBC deformations with high speed video. We demonstrate that the Kelvin Voigt model captures the stretching dynamics, and that the RBC membrane elastic shear modulus increases approximately linearly with increasing strain rate.

  3. 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. PMID:25533344

  4. Transit Characteristics of a Neutrophil Passing Through a Circular Constriction in a Cylindrical Capillary Vessel

    NASA Astrophysics Data System (ADS)

    Shirai, Atsushi; Fujita, Ryo; Hayase, Toshiyuki

    The former analysis of neutrophil's transit through pulmonary capillary network used the result of a micropipette aspiration experiment to model the transit in single capillary segment despite blunt tip geometry of the pipette is largely different from the real capillary segment. In the previous work, we have numerically investigated the transit of passive and fMLP-stimulated neutrophils through an arc-shaped constriction, establishing the analytical expression for the transit time. This paper intends to give a simplified model for the transit of a neutrophil through a capillary segment based on the numerical analysis and the stress-strain relationship of a Maxwell material. It is shown that the transit time is in proportion to the viscosity of the cell and in inverse proportion to the square root of the curvature radius of the constriction. The definition of the driving pressure of the cell into a micropipette is also applicable to that into the constriction.

  5. 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. PMID:25528974

  6. Electronic triple-dot transport through a bilayer graphene island with ultrasmall constrictions

    NASA Astrophysics Data System (ADS)

    Bischoff, D.; Varlet, A.; Simonet, P.; Ihn, T.; Ensslin, K.

    2013-08-01

    A quantum dot has been etched in bilayer graphene connected by two small constrictions to the leads. We show that this structure does not behave like a single quantum dot but consists of at least three sites of localized charge in series. The high symmetry and electrical stability of the device allowed us to triangulate the positions of the different sites of localized charge and find that one site is located in the island and one in each of the constrictions. Nevertheless we measure many consecutive non-overlapping Coulomb-diamonds in series. In order to describe these findings, we treat the system as a strongly coupled serial triple quantum dot. We find that the non-overlapping Coulomb diamonds arise due to higher order cotunneling through the outer dots located in the constrictions. We extract all relevant capacitances, simulate the measured data with a capacitance model and discuss its implications on electrical transport.

  7. 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.

  8. Numerical Simulation of Passage of a Neutrophil through a Rectangular Channel with a Moderate Constriction

    PubMed Central

    Shirai, Atsushi; Masuda, Sunao

    2013-01-01

    The authors have previously presented a mathematical model to predict transit time of a neutrophil through an alveolar capillary segment which was modeled as an axisymmetric arc-shaped constriction settled in a cylindrical straight pipe to investigate the influence of entrance curvature of a capillary on passage of the cell. The axially asymmetric cross section of a capillary also influences the transit time because it requires three-dimensional deformation of a cell when it passes through the capillary and could lead to plasma leakage between the cell surface and the capillary wall. In this study, a rectangular channel was introduced, the side walls of which were moderately constricted, as a representative of axially asymmetric capillaries. Dependence of transit time of a neutrophil passing through the constriction on the constriction geometry, i.e., channel height, throat width and curvature radius of the constriction, was numerically investigated, the transit time being compared with that through the axisymmetric model. It was found that the transit time is dominated by the throat hydraulic diameter and curvature radius of the constriction and that the throat aspect ratio little affects the transit time with a certain limitation, indicating that if an appropriate curvature radius is chosen, such a rectangular channel model can be substituted for an axisymmetric capillary model having the same throat hydraulic diameter in terms of the transit time by choosing an appropriate curvature radius. Thus, microchannels fabricated by the photolithography technique, whose cross section is generally rectangular, are expected to be applicable to in vitro model experiments of neutrophil retention and passage in the alveolar capillaries. PMID:23527190

  9. Diffuse and constricted modes of a dc discharge in neon: Simulation of the hysteresis transition

    SciTech Connect

    Shkurenkov, I. A.; Mankelevich, Yu. A.; Rakhimova, T. V.

    2008-09-15

    Results are presented from theoretical studies of high-pressure ({approx}100 Torr) dc discharges in neon. The diffuse and constricted discharge modes are studied using a model including the equation of balance for charged and excited particles, heat conduction equations for the neutral gas and plasma electrons, and Poisson's equation for the radial electric field at a fixed total discharge current. A specific feature of the constricted mode in the investigated range of low fields and high degrees of ionization is that the excitation and ionization rates in the center of the discharge tube and at the periphery differ by several orders of magnitude. This implies that, in the constricted mode, the region where the electron energy distribution function is Maxwellian due to electron-electron collisions may adjoin the region (beyond the constriction zone) where the high-energy part of the distribution function is depleted. The hysteresis transition between the diffuse and constricted modes is analyzed. A transition from the constricted to the diffuse mode can be regarded as a manifestation of the nonlocal character of the formation of the electron distribution function, specifically, the diffusion of high-energy electrons capable of producing gas ionization from the central (constricted) region toward the periphery. The nonlocal formation of the distribution function is described by a nonlocal kinetic equation accounting for electron-electron collisions and electron transport along the radius of the discharge tube. Since only high-energy electrons produce gas ionization, the effect of the nonlocal formation of the electron distribution function is taken into account by introducing the effective temperature of the high-energy part of the distribution function and solving the equation for the radial profile of the high-energy part of the distribution function. This approach allows one to approximately take into account the nonlocal character of the electron distribution

  10. 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

  11. 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.

  12. Red Blood Cells from Individuals with Abdominal Obesity or Metabolic Abnormalities Exhibit Less Deformability upon Entering a Constriction

    PubMed Central

    Zeng, Nancy F.; Mancuso, Jordan E.; Zivkovic, Angela M.; Smilowitz, Jennifer T.; Ristenpart, William D.

    2016-01-01

    Abdominal obesity and metabolic syndrome (MS) are multifactorial conditions associated with increased risk of cardiovascular disease and type II diabetes mellitus. Previous work has demonstrated that the hemorheological profile is altered in patients with abdominal obesity and MS, as evidenced for example by increased whole blood viscosity. To date, however, no studies have examined red blood cell (RBC) deformability of blood from individuals with obesity or metabolic abnormalities under typical physiological flow conditions. In this study, we pumped RBCs through a constriction in a microfluidic device and used high speed video to visualize and track the mechanical behavior of ~8,000 RBCs obtained from either healthy individuals (n = 5) or obese participants with metabolic abnormalities (OMA) (n = 4). We demonstrate that the OMA+ cells stretched on average about 25% less than the healthy controls. Furthermore, we examined the effects of ingesting a high-fat meal on RBC mechanical dynamics, and found that the postprandial period has only a weak effect on the stretching dynamics exhibited by OMA+ cells. The results suggest that chronic rigidification of RBCs plays a key role in the increased blood pressure and increased whole blood viscosity observed in OMA individuals and was independent of an acute response triggered by consumption of a high-fat meal. Trial Registration ClinicalTrials.gov NCT01803633 PMID:27258098

  13. 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.

  14. 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

  15. Nanopatterning and Hot Spot Modeling of YBCO Ultrathin Film Constrictions for THz Mixers

    NASA Astrophysics Data System (ADS)

    Ladret, Romain G.; Degardin, Annick F.; Kreisler, Alain J.

    2013-06-01

    High-TC hot electron bolometers (HEB) are promising THz mixers due to their expected wide bandwidth, large mixing gain, and low intrinsic noise. To achieve this goal, 0.6-μm-size constrictions were patterned on YBaCuO-based, 10-40-nm-thick films grown on (100) MgO substrates, which as previously reported, exhibited good DC superconducting properties. In this paper, we have simulated the DC and mixer characteristics of YBaCuO HEBs with a hot spot model usually dedicated to low-TC devices. For a 100 nm × 100 nm × 10 nm constriction, the expected double sideband noise temperature TN is 2000 K for 5 μW local oscillator (LO) power (G = -13.5 dB conversion gain). For a larger (but more realistic according to YBaCuO aging effects) 600 nm × 1000 nm × 35 nm constriction, TN = 1300 K at 200 μW LO power (G = -12 dB). This approach is expected to allow optimizing the operation of the HEB constriction coupled to a THz planar antenna.

  16. Transpalatal distraction for the management of maxillary constriction in pediatric patients

    PubMed Central

    Adolphs, Nicolai; Ernst, Nicole; Hoffmeister, Bodo; Raguse, Jan-Dirk

    2015-01-01

    Context: The management of severe maxillary constriction can be challenging. For that purpose surgically assisted maxillary expansion by transpalatal distraction (TPD) can typically be recommended after skeletal maturity. However in selected cases bone borne transpalatal distraction devices can contribute to improve maxillary constriction considerably earlier already during mixed dentition. Aims: To assess the possibility of bone borne transpalatal distraction in pediatric patients. Settings and Design: Clinical paper. Materials and Methods: Since 2010 TPD has been applied to six pediatric patients during mixed dentition when severe maxillary constriction was present and conventional orthodontic widening has already failed. Individually selected devices (Surgitec, Belgium) were inserted in general anaesthesia and distraction was performed according to well known parameters. Results: Maxillary constriction could be improved in all six patients without any drawbacks by bone borne devices during mixed dentition. Skeletal conditions were obviously improved for subsequent orthodontic or orthognathic therapy without functional impairment. Follow-up is up to 36 months after device removal. Conclusions: Transpalatal Distraction is recommendable in selected pediatric patients if massive growth disturbance is present or has to be expected. TPD allows for individually adapted maxillary expansion by selection and positioning of appropriate devices in combination with intraoperative testing of maxillary movements and controlled bone removal. PMID:26389033

  17. 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

  18. Changes in bovine vascular contraction and constriction relative to time off endophyte-infected tall fescue

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Beef cattle grazing endophyte-infected (E+; Neotyphodium coenophialum) tall fescue (TF; Lolium arundinaceum) are exposed to ergot alkaloids when consuming forage. Ergot alkaloids induce constriction in vascular tissue of extremities of animals grazing TF leading to inability to regulate body tempera...

  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. Minimizing the caliber of myelinated axons by means of nodal constrictions.

    PubMed

    Johnson, Christopher; Holmes, William R; Brown, Anthony; Jung, Peter

    2015-09-01

    In myelinated axons, most of the voltage-gated ion channels are concentrated at the nodes of Ranvier, which are short gaps in the myelin sheath. This arrangement leads to saltatory conduction and a larger conduction velocity than in nonmyelinated axons. Intriguingly, axons in the peripheral nervous system that exceed about 2 μm in diameter exhibit a characteristic narrowing of the axon at nodes that results in a local reduction of the axonal cross-sectional area. The extent of constriction increases with increasing internodal axonal caliber, reaching a threefold reduction in diameter for the largest axons. In this paper, we use computational modeling to investigate the effect of nodal constrictions on axonal conduction velocity. For a fixed number of ion channels, we find that there is an optimal extent of nodal constriction which minimizes the internodal axon caliber that is required to achieve a given target conduction velocity, and we show that this is sensitive to the precise geometry of the axon and myelin sheath in the flanking paranodal regions. Thus axonal constrictions at nodes of Ranvier appear to be a biological adaptation to minimize axonal volume, thereby maximizing the spatial and metabolic efficiency of these processes, which can be a significant evolutionary constraint. We show that the optimal nodal morphologies are relatively insensitive to changes in the number of nodal sodium channels. PMID:26224772

  1. 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

  2. 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

  3. Case report: pericardial effusion with constrictive physiology in a patient with wet beriberi.

    PubMed

    Yamamura, Minako; Murai, Hisayoshi; Kaneko, Shuichi; Usui, Soichiro; Furusho, Hiroshi; Takamura, Masayuki

    2016-01-01

    Wet beriberi-induced pericardial effusion has rarely been previously described. Little is known about the effect of beriberi-induced pericardial effusion on hemodynamics. Here we present a case of wet beriberi with pericardial effusion that exhibited constrictive physiology, which was dramatically improved after treatment. A 61-year-old male patient was admitted to our hospital for progressive leg edema, dyspnea on exertion, and lower-extremity muscle weakness. Echocardiography showed a hyperkinetic left ventricle and a moderate amount of pericardial effusion. Hemodynamic measurements, including simultaneous measurement of left and right ventricular pressures, revealed high output heart failure and constrictive physiology. Blood test showed lactic acidosis, and low level of serum thiamine levels; consistent with a diagnosis of wet beriberi. After thiamine replacement therapy, the patient's hemodynamic state rapidly improved. Additionally, pericardial effusion decreased and constrictive physiology was successfully resolved. No other possible causes of pericardial effusion could be identified, with the exception of thiamine deficiency. This case illustrates the importance of considering wet beriberi as a possible cause of pericardial effusion with constrictive physiology. PMID:27059308

  4. Ameliorative role of gemfibrozil against partial abdominal aortic constriction-induced cardiac hypertrophy in rats.

    PubMed

    Singh, Amrit Pal; Singh, Randhir; Krishan, Pawan

    2015-04-01

    Fibrates are peroxisome proliferator-activated receptor-α agonists and are clinically used for treatment of dyslipidemia and hypertriglyceridemia. Fenofibrate is reported as a cardioprotective agent in various models of cardiac dysfunction; however, limited literature is available regarding the role of gemfibrozil as a possible cardioprotective agent, especially in a non-obese model of cardiac remodelling. The present study investigated the role of gemfibrozil against partial abdominal aortic constriction-induced cardiac hypertrophy in rats. Cardiac hypertrophy was induced by partial abdominal aortic constriction in rats and they survived for 4 weeks. The cardiac hypertrophy was assessed by measuring left ventricular weight to body weight ratio, left ventricular wall thickness, and protein and collagen content. The oxidative stress in the cardiac tissues was assessed by measuring thiobarbituric acid-reactive substances, superoxide anion generation, and reduced glutathione level. The haematoxylin-eosin and picrosirius red staining was used to observe cardiomyocyte diameter and collagen deposition, respectively. Moreover, serum levels of cholesterol, high-density lipoproteins, triglycerides, and glucose were also measured. Gemfibrozil (30 mg/kg, p.o.) was administered since the first day of partial abdominal aortic constriction and continued for 4 weeks. The partial abdominal aortic constriction-induced cardiac oxidative stress and hypertrophy are indicated by significant change in various parameters used in the present study that were ameliorated with gemfibrozil treatment in rats. No significant change in serum parameters was observed between various groups used in the present study. It is concluded that gemfibrozil ameliorates partial abdominal aortic constriction-induced cardiac oxidative stress and hypertrophy and in rats. PMID:24905340

  5. 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.

  6. 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.

  7. Interplay of induced charge electroosmosis, electrothermal flow, and dielectrophoresis at insulating constrictions

    NASA Astrophysics Data System (ADS)

    Dingari, Naga Neehar; Wang, Qianru; Buie, Cullen

    2014-11-01

    We present a theoretical and experimental study on the combined influence of induced charge electroosmotic flow (ICEO) and electrothermal flow on particle motion in an insulator based dielectrophoretic (iDEP) device. Strong electric fields used for particle trapping induce charges on the channel wall of low, but finite permittivity, and also induce strong temperature gradients because of Joule heating. Consequently, the background fluid flow near the constriction is a superposition of these two effects. Our analysis presents a hitherto unexplored interplay between these two effects and how they influence particles which also experience dielectrophoresis. From our analysis, we find that for channels of low surface permittivity and conductivity, electrothermal effects are stronger near the constriction compared to ICEO effects, while the opposite is true when the surface permittivity or conductivity (or both) are comparable to that of bulk fluid. The analysis also includes the pH and electrolyte concentration dependent contributions of the dynamic Stern layer on ICEO flow.

  8. Approximate analytical calculation of the mach configuration of steady shock waves in a plane constricting channel

    NASA Astrophysics Data System (ADS)

    Medvedev, A. E.; Fomin, V. M.

    1998-05-01

    An approximate analytical model for calculation of the parameters of a steady gas flow inside a plane constricting channel formed by two symmetrically positioned wedges is suggested. A Mach configuration of shock waves (triple point) is formed in the channel when the wedge angles are larger than some critical value. The flow calculation in a constricting channel reduces to the solution of the iterative problem for a system of nonlinear algebraic equations. The configurations of shock waves, the slipstream, and the sonic line are described by the proposed model of a gas flow. A comparison of the results obtained using this model allows a fairly accurate calculation of the Mach stem and the length of the subsonic-flow region.

  9. Constrictive pericarditis following surgical repair of a peritoneopericardial diaphragmatic hernia in a cat.

    PubMed

    Murphy, Lisa A; Russell, Nicholas J; Dulake, Michelle I; Nakamura, Reid K

    2014-08-01

    A 4-year-old female spayed domestic longhair cat was referred for dyspnea. Further diagnostics revealed severe pleural effusion and a peritoneopericardial diaphragmatic hernia (PPDH). Following surgical correction of the PPDH the pleural effusion persisted. Re-check echocardiogram 4 weeks after initial evaluation revealed leftward deviation of the interventricular septum and interatrial septum occurring with inspiration. There were also exaggerated phasic changes in trans-tricuspid flow velocities suggestive of constrictive pericardial disease. Cardiac catheterization was performed and revealed elevated pressures in the right atrium and right ventricle. Constrictive pericarditis (CP) and epicarditis was confirmed at surgery, where subtotal pericardiectomy was performed with epicardial decortication. The cat continued to develop recurrent pleural effusion after surgery, although the volume and frequency of recurrence slowed over time. This is the first reported case of CP following PPDH repair in a cat. PMID:24789591

  10. 15-oxo-ETE-induced internal carotid artery constriction in hypoxic rats is mediated by potassium channels.

    PubMed

    Wang, D; Liu, Y; Lu, P; Zhu, D; Zhu, Y

    2016-07-18

    Our own study as well as others have previously reported that hypoxia activates 15-lipoxygenase (15-LO) in the brain, causing a series of chain reactions, which exacerbates ischemic stroke. 15-hydroxyeicosatetraenoic acid (15-HETE) and 15-oxo-eicosatetraenoic acid (15-oxo-ETE/15-KETE) are 15-LO-specific metabolites of arachidonic acid (AA). 15-HETE was found to be rapidly converted into 15-oxo-ETE by 15-hydroxyprostaglandin dehydrogenase (15-PGDH) in some circumstances. We have demonstrated that 15-HETE promotes cerebral vasoconstriction during hypoxia. However, the effect of 15-oxo-ETE upon the contraction of cerebral vasculature remains unclear. To investigate this effect and to clarify the underlying mechanism, we performed immunohistochemistry and Western blot to test the expression of 15-PGDH in rat cerebral tissue, examined internal carotid artery (ICA) tension in isolated rat ICA rings. Western blot and reverse transcription polymerase chain reaction (RT-PCR) were used to analyze the expression of voltage-gated potassium (Kv) channels (Kv2.1, Kv1.5, and Kv1.1) in cultured cerebral arterial smooth muscle cells (CASMCs). The results showed that the levels of 15-PGDH expression were drastically elevated in the cerebral of rats with hypoxia, and 15-oxo-ETE enhanced ICA contraction in a dose-dependent manner. This effect was more significant in the hypoxic rats than in the normoxic rats. We also found that 15-oxo-ETE significantly attenuated the expression of Kv2.1 and Kv1.5, but not Kv1.1. In conclusion, these results suggest that 15-oxo-ETE leads to the contraction of the ICA, especially under hypoxic conditions and that specific Kv channels may play an important role in 15-oxo-ETE-induced ICA constriction. PMID:26447508

  11. 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

  12. Hydrogen Peroxide Elicits Constriction of Skeletal Muscle Arterioles by Activating the Arachidonic Acid Pathway

    PubMed Central

    Csató, Viktória; Pető, Attila; Koller, Ákos; Édes, István

    2014-01-01

    Aims The molecular mechanisms of the vasoconstrictor responses evoked by hydrogen peroxide (H2O2) have not been clearly elucidated in skeletal muscle arterioles. Methods and Results Changes in diameter of isolated, cannulated and pressurized gracilis muscle arterioles (GAs) of Wistar-Kyoto rats were determined under various test conditions. H2O2 (10–100 µM) evoked concentration-dependent constrictions in the GAs, which were inhibited by endothelium removal, or by antagonists of phospholipase A (PLA; 100 µM 7,7-dimethyl-(5Z,8Z)-eicosadienoic acid), protein kinase C (PKC; 10 µM chelerythrine), phospholipase C (PLC; 10 µM U-73122), or Src family tyrosine kinase (Src kinase; 1 µM Src Inhibitor-1). Antagonists of thromboxane A2 (TXA2; 1 µM SQ-29548) or the non-specific cyclooxygenase (COX) inhibitor indomethacin (10 µM) converted constrictions to dilations. The COX-1 inhibitor (SC-560, 1 µM) demonstrated a greater reduction in constriction and conversion to dilation than that of COX-2 (celecoxib, 3 µM). H2O2 did not elicit significant changes in arteriolar Ca2+ levels measured with Fura-2. Conclusions These data suggest that H2O2 activates the endothelial Src kinase/PLC/PKC/PLA pathway, ultimately leading to the synthesis and release of TXA2 by COX-1, thereby increasing the Ca2+ sensitivity of the vascular smooth muscle cells and eliciting constriction in rat skeletal muscle arterioles. PMID:25093847

  13. Thyroid bud morphogenesis requires CDC42- and SHROOM3-dependent apical constriction

    PubMed Central

    Loebel, David A. F.; Plageman, Timothy F.; Tang, Theresa L.; Jones, Vanessa J.; Muccioli, Maria; Tam, Patrick P. L.

    2016-01-01

    ABSTRACT Early development of the gut endoderm and its subsequent remodeling for the formation of organ buds are accompanied by changes to epithelial cell shape and polarity. Members of the Rho-related family of small GTPases and their interacting proteins play multiple roles in regulating epithelial morphogenesis. In this study we examined the role of Cdc42 in foregut development and organ bud formation. Ablation of Cdc42 in post-gastrulation mouse embryos resulted in a loss of apical-basal cell polarity and columnar epithelial morphology in the ventral pharyngeal endoderm, in conjunction with a loss of apical localization of the known CDC42 effector protein PARD6B. Cell viability but not proliferation in the foregut endoderm was impaired. Outgrowth of the liver, lung and thyroid buds was severely curtailed in Cdc42-deficient embryos. In particular, the thyroid bud epithelium did not display the apical constriction that normally occurs concurrently with the outgrowth of the bud into the underlying mesenchyme. SHROOM3, a protein that interacts with Rho GTPases and promotes apical constriction, was strongly expressed in the thyroid bud and its sub-cellular localization was disrupted in Cdc42-deficient embryos. In Shroom3 gene trap mutant embryos, the thyroid bud epithelium showed no apical constriction, while the bud continued to grow and protruded into the foregut lumen. Our findings indicate that Cdc42 is required for epithelial polarity and organization in the endoderm and for apical constriction in the thyroid bud. It is possible that the function of CDC42 is partly mediated by SHROOM3. PMID:26772200

  14. 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

  15. 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

  16. Possible oriented transition of multiple-emulsion globules with asymmetric internal structures in a microfluidic constriction

    NASA Astrophysics Data System (ADS)

    Wang, Jingtao; Li, Xiaoduan; Wang, Xiaoyong; Guan, Jing

    2014-05-01

    When a globule with a complete symmetry (such as simple spherical droplets and concentric double emulsions) is transiting in a constriction tube, there is only one pattern of the transition. However, for a multiple-emulsion globule with asymmetric internal structures, there are many possible patterns with different pressure drops Δp due to various initial orientations of the inner droplets. In this paper, a boundary integral method developed recently is employed to investigate numerically the possible oriented transition of a globule with two unequal inner droplets in an axisymmetric microfluidic constriction. The transition is driven by an axisymmetric Poiseuille flow with a fixed volume flow rate, and the rheological behaviors of the globule are observed carefully. When the big inner droplet is initially located in the front of the globule, the maximum pressure drop during the transition is always lower than that when it is initially placed in the rear. Thus, a tropism—whereby a globule more easily gets through the constriction when its bigger inner droplet locates in its front initially—might exist, in which the orientating stimulus is the required pressure drops. The physical explanation of this phenomenon has also been analyzed in this paper.

  17. 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

  18. A PLCγ1-Dependent, Force-Sensitive Signaling Network in the Myogenic Constriction of Cerebral Arteries

    PubMed Central

    Gonzales, Albert L.; Yang, Ying; Sullivan, Michelle N.; Sanders, Lindsey; Dabertrand, Fabrice; Hill-Eubanks, David C.; Nelson, Mark T.; Earley, Scott

    2014-01-01

    Maintaining constant blood flow in the face of fluctuations in blood pressure is a critical autoregulatory feature of cerebral arteries. An increase in pressure within the artery lumen causes the vessel to constrict through depolarization and contraction of the encircling smooth muscle cells. This pressure-sensing mechanism involves activation of two types of transient receptor potential (TRP) channels: TRPC6 and TRPM4. We provide evidence that the activation of the γ1 isoform of phospholipase C (PLCγ1) is critical for pressure sensing in cerebral arteries. Inositol 1,4,5-trisphosphate (IP3), generated by PLCγ1 in response to pressure, sensitized IP3 receptors (IP3Rs) to Ca2+ influx mediated by the mechanosensitive TRPC6 channel, synergistically increasing IP3R-mediated Ca2+ release to activate TRPM4 currents, leading to smooth muscle depolarization and constriction of isolated cerebral arteries. Proximity ligation assays demonstrated colocalization of PLCγ1 and TRPC6 with TRPM4, suggesting the presence of a force-sensitive, local signaling network comprising PLCγ1, TRPC6, TRPM4, and IP3Rs. Src tyrosine kinase activity was necessary for stretch-induced TRPM4 activation and myogenic constriction, consistent with the ability of Src to activate PLCγ isoforms. We conclude that contraction of cerebral artery smooth muscle cells requires the integration of pressure-sensing signaling pathways and their convergence on IP3Rs, which mediate localized Ca2+-dependent depolarization through the activation of TRPM4. PMID:24866019

  19. Iodixanol, Constriction of Medullary Descending Vasa Recta, and Risk for Contrast Medium–induced Nephropathy

    PubMed Central

    Sendeski, Mauricio; Patzak, Andreas; Pallone, Thomas L.; Cao, Chunhua; Persson, A. Erik; Persson, Pontus B.

    2009-01-01

    Purpose: To determine whether a type of contrast medium (CM), iodixanol, modifies outer medullary descending vasa recta (DVR) vasoreactivity and nitric oxide (NO) production in isolated microperfused DVR. Materials and Methods: Animal handling conformed to the Animal Care Committee Guidelines of all participating institutions. Single specimens of DVR were isolated from rats and perfused with a buffered solution containing iodixanol. A concentration of 23 mg of iodine per milliliter was chosen to mimic that expected to be used in usual examinations in humans. Luminal diameter was determined by using video microscopy, and NO was measured by using fluorescent techniques. Results: Iodixanol led to 52% reduction of DVR luminal diameter, a narrowing that might interfere with passage of erythrocytes in vivo. Vasoconstriction induced by angiotensin II was enhanced by iodixanol. Moreover, iodixanol decreased NO bioavailability by more than 82%. Use of 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl (a superoxide dismutase mimetic) prevented both vasoconstriction with iodixanol alone and increased constriction with angiotensin II caused by CM. Conclusion: Iodixanol in doses typically used for coronary interventions constricts DVR, intensifies angiotensin II–induced constriction, and reduces bioavailability of NO. CM-induced nephropathy may be related to these events and scavenging of reactive oxygen species might exert a therapeutic benefit by preventing the adverse effects that a CM has on medullary perfusion. © RSNA, 2009 PMID:19366904

  20. 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

  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. Saturn's Spectacular Ring System

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    Saturn's beautiful rings have fascinated astronomers since they were first observed by Galileo in 1610. The main rings consist of solid particles mostly in the 1 cm - 10 m range, composed primarily of water ice. The ring disk is exceptionally thin - the typical local thickness of the bright rings is tens of meters, whereas the diameter of the main rings is 250,000 km! The main rings exhibit substantial radial variations "ringlets", many of which are actively maintained via gravitational perturbations from Saturn's moons. Exterior to the main rings lie tenuous dust rings, which have little mass but occupy a very large volume of space. This seminar will emphasize the physics of ring-moon interactions, recent advances in our understanding of various aspects of the rings obtained from observations taken during 1995 when the rings appeared edge-on to the Earth and then to the Sun, and observations in subsequent years from HST.

  3. 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

  4. Does pupil constriction under blue and green monochromatic light exposure change with age?

    PubMed

    Daneault, Véronique; Vandewalle, Gilles; Hébert, Marc; Teikari, Petteri; Mure, Ludovic S; Doyon, Julien; Gronfier, Claude; Cooper, Howard M; Dumont, Marie; Carrier, Julie

    2012-06-01

    Many nonvisual functions are regulated by light through a photoreceptive system involving melanopsin-expressing retinal ganglion cells that are maximally sensitive to blue light. Several studies have suggested that the ability of light to modulate circadian entrainment and to induce acute effects on melatonin secretion, subjective alertness, and gene expression decreases during aging, particularly for blue light. This could contribute to the documented changes in sleep and circadian regulatory processes with aging. However, age-related modification in the impact of light on steady-state pupil constriction, which regulates the amount of light reaching the retina, is not demonstrated. We measured pupil size in 16 young (22.8±4 years) and 14 older (61±4.4 years) healthy subjects during 45-second exposures to blue (480 nm) and green (550 nm) monochromatic lights at low (7×10(12) photons/cm2/s), medium (3×10(13) photons/cm2/s), and high (10(14) photons/cm2/s) irradiance levels. Results showed that young subjects had consistently larger pupils than older subjects for dark adaptation and during all light exposures. Steady-state pupil constriction was greater under blue than green light exposure in both age groups and increased with increasing irradiance. Surprisingly, when expressed in relation to baseline pupil size, no significant age-related differences were observed in pupil constriction. The observed reduction in pupil size in older individuals, both in darkness and during light exposure, may reduce retinal illumination and consequently affect nonvisual responses to light. The absence of a significant difference between age groups for relative steady-state pupil constriction suggests that other factors such as tonic, sympathetic control of pupil dilation, rather than light sensitivity per se, account for the observed age difference in pupil size regulation. Compared to other nonvisual functions, the light sensitivity of steady-state pupil constriction appears to

  5. 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.

  6. 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.

  7. 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

  8. 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 ...

  9. A patient with constitutional ring 1 chromosome characterized by SNP array CGH.

    PubMed

    Saliganan, Sheila; Lee, Joanna; Wei, Sainan

    2016-04-01

    We present a male patient with constitutional ring 1 chromosome and subsequent 6 Mb deletion at 1q43q44. The patient displays overlapping clinical features with reported patients with ring 1 chromosome and 1q43q44 microdeletion syndrome. To our knowledge, this is the first patient with ring 1 chromosome characterized by comparative genomic hybridization. PMID:27099748

  10. 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.

  11. The Bi-Digital O-Ring Test used in the successful diagnosis & treatment (with antibiotic, anti-viral agents & oriental herbal medicine) of a patient suffering from pain & weakness of an upper extremity & Barré-Liéou syndrome appearing after whiplash injury. A case report.

    PubMed

    Ayuzawa, S; Yano, H; Enomoto, T; Kobayashi, H; Nose, T

    1997-01-01

    A patient with a whiplash injury suffering from prolonged symptoms, including pain and weakness of the right upper extremity and the symptoms of Barré-Liéou syndrome, was diagnosed and treated with the Bi-Digital O-Ring Test as a supplement to standard medical examinations. Radiological findings showed spondylotic canal stenosis with osteophytes and disc protrusions. The Bi-Digital O-Ring Test indicated a strong abnormal response around the right side of his neck and right shoulder, including the area of the vertebral artery and at acupuncture point GB 21, where positive resonant responses to Cytomegalovirus and Streptococcus faecalis were detected. Antibiotic and anti-viral agents, as well as Ku-Oketsu-Zai, a type of Oriental herbal medicine for overcoming blood stagnation or stasis, were administered according to the drug compatibility test using the Bi-Digital O-ring Test and the following clinical results were obtained. Infection at the site of the vertebral artery and the peri-arterial sympathetic nerve plexus was considered as a cause of the prolongation of the symptoms including Barré-Liéou syndrome, in this case. In addition we especially noted, in this clinical case, that the patient's impaired grasping force dramatically improved from 8 kg to 52 kg in a very short periods of time when the patient held suitable medicine selected with the Bi-Digital O-Ring Test drug compatibility test. We assume that the drug action was transferred electromagnetically, by which the pathological electromagnetic oscillations caused by trauma and following infections were scavenged. This effect might lead to an improvement in the coordination of the neuromuscular system. PMID:9494625

  12. Genetics Home Reference: ring chromosome 20 syndrome

    MedlinePlus

    ... common feature of this condition is recurrent seizures (epilepsy) in childhood. The seizures may occur during the ... appear either before or after the onset of epilepsy, they tend to worsen after seizures develop. Additional ...

  13. Eph-Ephrin signaling and focal adhesion kinase regulate actomyosin-dependent apical constriction of ciliary band cells.

    PubMed

    Krupke, Oliver A; Burke, Robert D

    2014-03-01

    Apical constriction typically accompanies inward folding of an epithelial sheet. In recent years there has been progress in understanding mechanisms of apical constriction and their contribution to morphogenetic processes. Sea urchin embryos form a specialized region of ectoderm, the ciliary band, which is a strip of epithelium, three to five cells wide, encircling the oral ectoderm and functioning in larval swimming and feeding. Ciliary band cells exhibit distinctive apical-basal elongation, have narrow apices bearing a cilium, and are planar polarized, so that cilia beat away from the mouth. Here, we show that filamentous actin and phosphorylated myosin light chain are uniquely distributed in ciliary band cells. Inhibition of myosin phosphorylation or actin polymerization perturbs this distribution and blocks apical constriction. During ciliary band formation, Sp-Ephrin and Sp-Eph expression overlap in the presumptive ciliary band. Knockdown of Sp-Eph or Sp-Ephrin, or treatment with an Eph kinase inhibitor interferes with actomyosin networks, accumulation of phosphorylated FAK (pY(397)FAK), and apical constriction. The cytoplasmic domain of Sp-Eph, fused to GST and containing a single amino acid substitution reported as kinase dead, will pull down pY(397)FAK from embryo lysates. As well, pY(397)FAK colocalizes with Sp-Eph in a JNK-dependent, planar polarized manner on latitudinal apical junctions of the ciliary band and this polarization is dissociable from apical constriction. We propose that Sp-Eph and pY(397)FAK function together in an apical complex that is necessary for remodeling actomyosin to produce centripetal forces causing apical constriction. Morphogenesis of ciliary band cells is a unique example of apical constriction in which receptor-mediated cell shape change produces a strip of specialized tissue without an accompanying folding of epithelium. PMID:24550115

  14. Jupiter's Main Ring/Ring Halo

    NASA Technical Reports Server (NTRS)

    1997-01-01

    A mosaic of four images taken through the clear filter (610 nanometers) of the solid state imaging (CCD) system aboard NASA's Galileo spacecraft on November 8, 1996, at a resolution of approximately 46 kilometers (28.5 miles) per picture element (pixel) along Jupiter's rings. Because the spacecraft was only about 0.5 degrees above the ring plane, the image is highly foreshortened in the vertical direction. The images were obtained when Galileo was in Jupiter's shadow, peering back toward the Sun; the ring was approximately 2.3 million kilometers (1.4 million miles) away. The arc on the far right of the image is produced when sunlight is scattered by small particles comprising Jupiter's upper atmospheric haze. The ring also efficiently scatters light, indicating that much of its brightness is due to particles that are microns or less in diameter. Such small particles are believed to have human-scale lifetimes, i.e., very brief compared to the solar system's age.

    Jupiter's ring system is composed of three parts - - a flat main ring, a lenticular halo interior to the main ring, and the gossamer ring, outside the main ring. The near and far arms of Jupiter's main ring extend horizontally across the mosaic, joining together at the ring's ansa, on the figure's far left side. The near arm of the ring appears to be abruptly truncated close to the planet, at the point where it passes into Jupiter's shadow. Some radial structure is barely visible across the ring's ansa (top image). A faint mist of particles can be seen above and below the main rings. This vertically extended 'halo' is unusual in planetary rings, and is probably caused by electromagnetic forces pushing the smallest grains out of the ring plane. Because of shadowing, the halo is not visible close to Jupiter in the lower right part of the mosaic. To accentuate faint features in the bottom image of the ring halo, different brightnesses are shown through color. Brightest features are white or yellow and the

  15. On semi ring bornologies

    NASA Astrophysics Data System (ADS)

    Imran, A. N.; Rakhimov, I. S.; Husain, Sh. K. Said

    2016-06-01

    Our main focus in this work is to introduce new structure bornological semi rings. This generalizes the theory of algebraic semi rings from the algebraic setting to the framework of bornological sets. We give basic properties for this new structure. As well as, We study the fundamental construction of bornological semi ring as product, inductive limits and projective limits and their extensions on bornological semi ring. Additionally, we introduce the category of bornological semi rings and study product and pullback (fiber product) in the category of bornological semi rings.

  16. Prenatal constriction of the ductus arteriosus following maternal diclofenac medication in the third trimester.

    PubMed

    Aker, Karoline; Brantberg, Anne; Nyrnes, Siri Ann

    2015-01-01

    We describe a case of a 21-year-old primigravida at 36 weeks' gestation who was admitted to a local hospital because of abdominal pain. She was prescribed a total of six doses of diclofenac 50 mg over 2 days. One day later, there was difficulty registering the fetal heartbeats on cardiotocography. Ultrasound examination revealed a fetus with ascites and pathological flow over the tricuspid valve. The patient was referred to a tertiary centre for fetal medicine. Fetal echocardiography revealed, in addition to ascites and tricuspid regurgitation, a constricted ductus arteriosus, dilated right ventricle and reduced flow in the pulmonary artery. Immediate caesarean section resulted in an excellent neonatal outcome. PMID:26427495

  17. Influence of celecoxib on the vasodilating properties of human mesenteric arteries constricted with endothelin-1

    PubMed Central

    GRZEŚK, GRZEGORZ; SZADUJKIS-SZADURSKA, KATARZYNA; MATUSIAK, GRZEGORZ; MALINOWSKI, BARTOSZ; GAJDUS, MARTA; WICIŃSKI, MICHAŁ; SZADUJKIS-SZADURSKI, LESZEK

    2014-01-01

    The mitogenic and vasoconstrictive properties of the vascular system are attributed to endothelin-1 (ET-1). ET-1 serum concentration increases in a number of pathological conditions, particularly in those associated with blood vessel constriction. ET-1 is also associated with the underlying pathomechanisms of primary pulmonary hypertension, arterial hypertension and eclampsia. The aim of this study was to compare the vasodilating properties of selected phosphodiesterase (PDE) inhibitors and celecoxib in human mesenteric arteries constricted with ET-1, and investigate the role of the endothelium in relaxation. Perfused human mesenteric arteries were collected and stored under the same conditions as organs for transplantation. The mesenteric arteries (with and without the endothelium) were constricted by the addition of ET-1 and treated with one of the following: sildenafil (PDE5 inhibitor), zaprinast (PDE5 and 6 inhibitor), rolipram (PDE4 inhibitor) and celecoxib [cyclooxygenase-2 (COX-2) inhibitor]. Based on the observed changes of the perfusion pressure, concentration response curves (CRCs) were prepared for the respective inhibitors and the EC50 (concentration causing an effect equal to half of the maximum effect), pD2 (negative common logarithm of EC50) and relative potency (RP) were calculated. The results suggested that all the inhibitors triggered a concentration-dependent decrease in the perfusion pressure in isolated human superior mesenteric arteries with endothelium constricted by the addition of ET-1. In the arteries without endothelium, CRCs for celecoxib and rolipram were shifted to the right without a significant decrease in the maximum dilating effect. Moreover, CRCs for sildenafil and zaprinast were shifted to the right with a simultaneous significant decrease in the maximum dilating effect and with an increased inclination angle in reference to the concentration axis. In the presence of the endothelium, all of the evaluated PDE inhibitors, as well

  18. Influence of celecoxib on the vasodilating properties of human mesenteric arteries constricted with endothelin-1.

    PubMed

    Grześk, Grzegorz; Szadujkis-Szadurska, Katarzyna; Matusiak, Grzegorz; Malinowski, Bartosz; Gajdus, Marta; Wiciński, Michał; Szadujkis-Szadurski, Leszek

    2014-05-01

    The mitogenic and vasoconstrictive properties of the vascular system are attributed to endothelin-1 (ET-1). ET-1 serum concentration increases in a number of pathological conditions, particularly in those associated with blood vessel constriction. ET-1 is also associated with the underlying pathomechanisms of primary pulmonary hypertension, arterial hypertension and eclampsia. The aim of this study was to compare the vasodilating properties of selected phosphodiesterase (PDE) inhibitors and celecoxib in human mesenteric arteries constricted with ET-1, and investigate the role of the endothelium in relaxation. Perfused human mesenteric arteries were collected and stored under the same conditions as organs for transplantation. The mesenteric arteries (with and without the endothelium) were constricted by the addition of ET-1 and treated with one of the following: sildenafil (PDE5 inhibitor), zaprinast (PDE5 and 6 inhibitor), rolipram (PDE4 inhibitor) and celecoxib [cyclooxygenase-2 (COX-2) inhibitor]. Based on the observed changes of the perfusion pressure, concentration response curves (CRCs) were prepared for the respective inhibitors and the EC50 (concentration causing an effect equal to half of the maximum effect), pD2 (negative common logarithm of EC50) and relative potency (RP) were calculated. The results suggested that all the inhibitors triggered a concentration-dependent decrease in the perfusion pressure in isolated human superior mesenteric arteries with endothelium constricted by the addition of ET-1. In the arteries without endothelium, CRCs for celecoxib and rolipram were shifted to the right without a significant decrease in the maximum dilating effect. Moreover, CRCs for sildenafil and zaprinast were shifted to the right with a simultaneous significant decrease in the maximum dilating effect and with an increased inclination angle in reference to the concentration axis. In the presence of the endothelium, all of the evaluated PDE inhibitors, as well

  19. Epidemiology and risk factors of amniotic band syndrome, or ADAM sequence

    PubMed Central

    Cignini, Pietro; Giorlandino, Claudio; Padula, Francesco; Dugo, Nella; Cafà, Ester Valentina; Spata, Anna

    2012-01-01

    Summary Amniotic band sequence (ABS) is the term applied to a wide range of congenital anomalies, most typically limb and digital amputations and constriction rings, that occur in association with fibrous bands (1). These alterations may be associated or not with cutaneous and visceral abnormalities. This work, which is a literature review, examines several studies that relate to cases of amniotic band syndrome (SBA). In particular, our attention was focused on the causes and pathogenesis of the SBA. These for the most part are still unknown, but from what we observe in different jobs, are due to a mechanism of vascular damage. Therefore in this paper we examine chemical risk factors, like smoking, drug use, maternal hyperglycemia, mechanical risk factors such as the puncture of the amniotic sac after amniocentesis. We also speak of the altitude as a risk factor related to blood pressure, of the increased incidence of disease in primigravid, in women with a low level of education, in which the pregnancy was not planned, and then we talk of a higher incidence in young fathers and of the role of familiarity. PMID:23272276

  20. 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

  1. 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.

  2. 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

  3. 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

  4. Neptune - full ring system

    NASA Technical Reports Server (NTRS)

    1989-01-01

    This pair of Voyager 2 images (FDS 11446.21 and 11448.10), two 591-s exposures obtained through the clear filter of the wide angle camera, show the full ring system with the highest sensitivity. Visible in this figure are the bright, narrow N53 and N63 rings, the diffuse N42 ring, and (faintly) the plateau outside of the N53 ring (with its slight brightening near 57,500 km).

  5. 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

  6. 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

  7. Local cerebral hyperthermia induces spontaneous thrombosis and arteriolar constriction in the pia mater of the mouse

    NASA Astrophysics Data System (ADS)

    El-Sabban, Farouk; Fahim, Mohamed A.

    1995-06-01

    The effect of local cerebral hyperthermia on responses of pial microvessels of the mouse was investigated. A set protocol was followed, involving the performance of a craniotomy on anaesthetized animals and using intravital microscope-television closed circuitry. Controlled hyperthermic exposure was applied regionally by heating the brain surface with irrigating artificial cerebrospinal fluid. Microvascular responses such as changes in diameter, thrombosis and embolism were monitored and video-taped observations were further viewed and analysed. When both brain surface and core body temperatures were kept at 37° C, no changes in pial microvessels were noted. With core body temperature kept at 37° C and at a brain surface temperature of 43.1° C, passing emboli and arteriolar constriction were observed. A few minutes later, visible thrombosis was prevalent. Further spontaneous thrombo-embolic activity continued and at the end of a 50-min hyperthermic exposure, arterioles attained a constriction of 37%. Thrombus formation was sometimes massive enough to occlude fully the microvessel. The protocol followed in this study can be adopted to other small animal species and for a variety of experimental procedures involving hyperthermia and the pial microcirculation.

  8. 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. PMID:25974189

  9. Apical constriction drives tissue-scale hydrodynamic flow to mediate cell elongation.

    PubMed

    He, Bing; Doubrovinski, Konstantin; Polyakov, Oleg; Wieschaus, Eric

    2014-04-17

    Epithelial folding mediated by apical constriction converts flat epithelial sheets into multilayered, complex tissue structures and is used throughout development in most animals. Little is known, however, about 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 formation. We find that cytoplasmic redistribution during the lengthening phase of ventral furrow 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 before gastrulation ('acellular' embryos), such that the global redistribution of cytoplasm mirrors the summed redistribution occurring in individual cells of wild-type embryos. Our results indicate that during the lengthening phase of ventral furrow formation, hydrodynamic behaviour of the cytoplasm provides the predominant mechanism transmitting apically generated forces deep into the tissue and that cell individualization is dispensable. PMID:24590071

  10. Clinical characteristics of constrictive pericarditis diagnosed by echo-Doppler technique in Korea.

    PubMed Central

    Yang, H. S.; Song, J. K.; Song, J. M.; Kang, D. H.; Lee, C. W.; Nam, G. B.; Choi, K. J.; Kim, Y. H.; Hong, M. K.; Kim, J. J.; Park, S. W.; Park, S. J.; Song, H.; Lee, J. W.; Song, M. G.

    2001-01-01

    A retrospective analysis of clinical data of 71 patients with constrictive pericarditis (CP) diagnosed by echo-Doppler technique (mean age, 49+/-17) was done. In 27 patients (38%), the etiology was unknown, and the three most frequent identifiable causes were tuberculosis (23/71, 32%), cardiac surgery (8/71, 11%), and mediastinal irradiation (6/71, 9%). Pericardiectomy was performed in 35 patients (49%) with a surgical mortality of 6% (2/35), and 11 patients (15%, 11/ 71) showed complete resolution of constrictive physiology with medical treatment. Patients with transient CP were characterized by absence of pericardial calcification, shorter symptom duration, and higher incidence of fever, weight loss, and tuberculosis. The 5-yr survival rates of patients with transient CP and those undergoing pericardiectomy were 100% and 85+/-6%, respectively, which were significantly higher than that of patients without undergoing pericardiectomy (33+/-17%, p=0.0083). Mediastinal irradiation, higher functional class, low voltage in ECG, low serum albumin, and old age were the independent variables associated with a higher mortality. Tuberculosis is still the most important etiology of CP in Korea, and not infrequently, it may cause transient CP. Early diagnosis and decision-making using follow-up echocardiography are crucial to improve the prognosis of patients with CP. PMID:11641523

  11. Wall shear stress distributions in a model of normal and constricted small airways.

    PubMed

    Evans, David J; Green, Anthony S; Thomas, Nicholas K

    2014-04-01

    Previous studies have highlighted flow shear stress as a possible damage mechanism for small airways, in particular those liable to constriction through disease or injury due to mechanical ventilation. Flow experiments in vitro have implicated shear stress as a relevant factor for mechanotransduction pathways with respect to airway epithelial cell function. Using computational fluid dynamics analysis, this study reports velocity profiles and calculations for wall shear stress distributions in a three-generation, asymmetric section of the small airways subjected to a steady, inspiratory flow. The results show distal variation of wall shear stress distributions due to velocity gradients on the carina side of each daughter airway branch. The maximum wall shear stresses in both normal and constricted small airways are shown to exceed those calculated using data from previous simpler one-dimensional experimental analyses. These findings have implications for lung cell flow experiments involving shear stress in the consideration of both normal airway function and pathology due to mechanotransduction mechanisms. PMID:24618983

  12. Probing weak localization in chemical vapor deposition graphene wide constriction using scanning gate microscopy.

    PubMed

    Chuang, C; Matsunaga, M; Liu, F-H; Woo, T-P; Aoki, N; Lin, L-H; Wu, B-Y; Ochiai, Y; Liang, C-T

    2016-02-19

    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. PMID:26762929

  13. 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.

  14. 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…

  15. 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 0.75 million km from Saturn on 12 November 1980. The kinks and braids of this tightly-constrained ring are visible along with the outer edge of the A Ring. JPL managed the Voyager Project for NASA's Office of Space Science.

  16. 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)

  17. Isoflurane does not vasodilate rat thoracic aortic rings by endothelium-derived relaxing factor or other cyclic GMP-mediated mechanisms.

    PubMed

    Brendel, J K; Johns, R A

    1992-07-01

    Endothelium-derived relaxing factor (EDRF) is a potent endogenous vasodilator that has been indirectly suggested to play a role in isoflurane-mediated vasodilation. To examine directly the possible role of EDRF in isoflurane-mediated vasodilation, isolated rat thoracic aortic rings were suspended for isometric tension measurements, equilibrated to a resting tension of 2 g, and constricted with a 50% maximal concentration (EC50) dose of phenylephrine or KCl. Three groups of rings were studied: endothelium-intact, endothelium-denuded, and endothelium-intact rings treated with nitro-L-arginine methyl ester (L-NAME), a specific inhibitor of EDRF synthase. Isoflurane was then added at 1, 2, and 3% in a cumulative manner, allowing 10 min for each concentration to equilibrate. Indomethacin was present in all experiments to prevent the formation of vasoactive prostanoid metabolites. Since EDRF causes vascular relaxation by stimulating soluble guanylyl cyclase and increasing cyclic GMP, the effect of isoflurane on vascular ring cyclic GMP content was determined as an additional indicator of EDRF-mediated dilation. Rings with intact and denuded endothelium were isolated as described above, constricted with phenylephrine, and challenged with methacholine (positive control) or 1, 2, or 3% isoflurane. After 8 min exposure, the rings were flash-frozen in dry-ice-cooled acetone and homogenized in 1 N HCl for subsequent analysis of cyclic GMP content by radioimmunoassay. Isoflurane caused dose-dependent vasodilation of both KCl- and phenylephrine-constricted rings. In the phenylephrine group, at 2% and 3% isoflurane, endothelium-denuded and L-NAME-treated rings relaxed to a greater extent than endothelium-intact rings (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1319121

  18. Jovian Ring System Mosaic

    NASA Technical Reports Server (NTRS)

    2000-01-01

    NASA's Galileo spacecraft acquired this mosaic of Jupiter's ring system (top) when the spacecraft was in Jupiter's shadow looking back toward the Sun. Jupiter's ring system (inset diagram) is composed of three parts: an outermost gossamer ring, a flat main ring, and an innermost donut-shaped halo. These rings are made up of dust-sized particles that are blasted off of the nearby inner satellites by small impacts. This image was taken on November 9, 1996 at a distance of 2.3 million kilometers (1.4 million miles).

  19. Constriction rate variation produced by partial ligation of the portal vein at pre-hepatic portal hypertension induced in rats

    PubMed Central

    RODRIGUES, Daren Athiê Boy; da SILVA, Aline Riquena; SERIGIOLLE, Leonardo Carvalho; FIDALGO, Ramiro de Sousa; FAVERO, Sergio San Gregorio; LEME, Pedro Luiz Squilacci

    2014-01-01

    Background Partial portal vein ligation causes an increase in portal pressure that remains stable even after the appearance of collateral circulation, with functional adaptation to prolonged decrease in portal blood flow. Aim To assess whether different constriction rates produced by partial ligation of the vein interfere with the results of this experimental model in rats. Methods Three groups of five rats each were used; in group 1 (sham-operated), dissection and measurement of portal vein diameters were performed. Portal hypertension was induced by partial portal vein ligation, reducing its size to 0.9 mm in the remaining 10 animals, regardless of the initial diameter of the veins. Five animals with portal hypertension (group 2) underwent reoperation after 15 days and the rats in group 3 after 30 days. The calculation of the constriction rate was performed using a specific mathematical formula (1 - π r 2 / π R2) x 100% and the statistical analysis with the Student t test. Results The initial diameter of the animal's portal vein was 2.06 mm, with an average constriction rate of the 55.88%; although the diameter of the veins and the constriction rate in group 2 were lower than in group 3 (2.06 mm - 55,25% and 2.08 mm - 56.51%, respectively), portal hypertension was induced in all rats and no significant macroscopic differences were found between the animals that were reoperated after 15 days and after 30 days respectively, being the shorter period considered enough for the evaluation. Comparing the initial diameter of the vein and the rate of constriction performed in groups 2 and 3, no statistic significance was found (p>0.05). Conclusion Pre-hepatic portal hypertension in rat can be induced by the reduction of the portal vein diameter to 0.9 mm, regardless the initial diameter of the vein and the vessel constriction rate. PMID:25626939

  20. Pupil constriction evoked in vitro by stimulation of the oculomotor nerve in the turtle (Trachemys scripta elegans).

    PubMed

    Dearworth, James R; Brenner, J E; Blaum, J F; Littlefield, T E; Fink, D A; Romano, J M; Jones, M S

    2009-01-01

    The pond turtle (Trachemys scripta elegans) exhibits a notably sluggish pupillary light reflex (PLR), with pupil constriction developing over several minutes following light onset. In the present study, we examined the dynamics of the efferent branch of the reflex in vitro using preparations consisting of either the isolated head or the enucleated eye. Stimulation of the oculomotor nerve (nIII) using 100-Hz current trains resulted in a maximal pupil constriction of 17.4% compared to 27.1% observed in the intact animal in response to light. When current amplitude was systematically increased from 1 to 400 microA, mean response latency decreased from 64 to 45 ms, but this change was not statistically significant. Hill equations fitted to these responses indicated a current threshold of 3.8 microA. Stimulation using single pulses evoked a smaller constriction (3.8%) with response latencies and threshold similar to that obtained using train stimulation. The response evoked by postganglionic stimulation of the ciliary nerve using 100-Hz trains was largely indistinguishable from that of train stimulation of nIII. However, application of single-pulse stimulation postganglionically resulted in smaller pupil constriction at all current levels relative to that of nIII stimulation, suggesting that there is amplification of efferent drive at the ganglion. Time constants for constrictions ranged from 88 to 154 ms with relaxations occurring more slowly at 174-361 ms. These values for timing from in vitro are much faster than the time constant 1.66 min obtained for the light response in the intact animal. The rapid dynamics of pupil constriction observed here suggest that the slow PLR of the turtle observed in vivo is not due to limitations of the efferent pathway. Rather, the sluggish response probably results from photoreceptive mechanisms or central processing. PMID:19523265

  1. 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. PMID:19812546

  2. Three-dimensional organization of the endoplasmic reticulum membrane around the mitochondrial constriction site in mammalian cells revealed by using focused-ion beam tomography.

    PubMed

    Ohta, Keisuke; Okayama, Satoko; Togo, Akinobu; Nakamura, Kei-Ichiro

    2014-11-01

    the specimens was freshly exposed using an ultramicrotome and examined by FIB/SEM (Quanta 3D FEG, FEI, USA). Ion-beam milling and image acquisition cycles were performed under the following conditions. The milling was performed with a gallium ion beam at 30 kV with a current of 100 pA, with a milling pitch of 10 nm/step. Material contrast images using backscattered electrons (BSE) were acquired at a landing energy of 2 keV with a bias voltage of 1.5-2.5 kV using a vCD detector. The remaining acquisition parameters were as follows: beam current = 11 pA, dwell time = 6-30 µs/pixel, image size = 1024 × 883 pixel (5.9 × 5.1 µm), pixel size = 5.8 nm/pixel. The resultant image stack was processed using Avizo 6.3 and Amira 5.4(FEI, USA).Reconstructed volume showed the existence of several constriction sites on mitochondria in both chemically fixed normal hepatocytes and HeLa cells. Each material contrast image of specimen surfaces showed two types of membrane associations between the ER and mitochondria. The first was an osmiophilic bridge-like structure; these bridges were approximately 50 nm in length, and they connected the ER membrane and the mitochondrial outer membrane (OMM). The second was a close apposition (< 20 nm) of the ER membrane and the OMM. Membrane segmentation revealed the 3D distribution of the membrane contacts; 10 to 20% of the mitochondrial surface was occupied by ER contacts. No fundamental difference was observed between hepatocytes and HeLa cells in the distribution pattern of the contacts. Although ER-contacts and bridge-like structures were occasionally found to accumulate around the mitochondrial constriction area, we did not observe any ring-like ER tubules around the mammalian mitochondrial constriction site, as in yeast. These results suggest that the role of ER-membrane associations in the mitochondrial fission process may differ between mammals and yeast. PMID:25359839

  3. 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

  4. Traceable Ring Signature

    NASA Astrophysics Data System (ADS)

    Fujisaki, Eiichiro; Suzuki, Koutarou

    The ring signature allows a signer to leak secrets anonymously, without the risk of identity escrow. At the same time, the ring signature provides great flexibility: No group manager, no special setup, and the dynamics of group choice. The ring signature is, however, vulnerable to malicious or irresponsible signers in some applications, because of its anonymity. In this paper, we propose a traceable ring signature scheme. A traceable ring scheme is a ring signature except that it can restrict “excessive” anonymity. The traceable ring signature has a tag that consists of a list of ring members and an issue that refers to, for instance, a social affair or an election. A ring member can make any signed but anonymous opinion regarding the issue, but only once (per tag). If the member submits another signed opinion, possibly pretending to be another person who supports the first opinion, the identity of the member is immediately revealed. If the member submits the same opinion, for instance, voting “yes” regarding the same issue twice, everyone can see that these two are linked. The traceable ring signature can suit to many applications, such as an anonymous voting on a BBS. We formalize the security definitions for this primitive and show an efficient and simple construction in the random oracle model.

  5. Sunset on Saturn's Rings

    NASA Technical Reports Server (NTRS)

    1996-01-01

    This is a rare view of Saturn's rings seen just after the Sun has set below the ring plane, taken with the Hubble Space Telescope on Nov. 21, 1995.

    This perspective is unusual because the Earth is slightly above (2.7 degrees latitude) Saturn's rings and the Sun is below them. Normally we see the rings fully illuminated by the Sun.

    The photograph shows three bright ring features: the F Ring, the Cassini Division, and the C Ring (moving from the outer rings to the inner). The low concentration of material in these rings allows light from the Sun to shine through them. The A and B rings are much denser, which limits the amount of light that penetrates through them. Instead, they are faintly visible because they reflect light from Saturn's disk.

    Scientists believe that the F Ring is slightly warped because it disappears part way around on the right (West) side. Hubble's high resolution shows the that A Ring's shadow obscures part of the F ring (right).

    The image was assembled from 20 exposures taken with Wide Field Planetary Camera-2 over 8 hours.

    The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science.

    This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/pubinfo/

  6. 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

  7. Portable, Constriction-Expansion Blood Plasma Separation and Polymerization-Based Malaria Detection.

    PubMed

    Shatova, Tatyana A; Lathwal, Shefali; Engle, Marissa R; Sikes, Hadley D; Jensen, Klavs F

    2016-08-01

    A portable, microfluidic blood plasma separation device is presented featuring a constriction-expansion design, which produces 100.0% purity for undiluted blood at 9% yield. This level of purity represents an improvement of at least 1 order of magnitude with increased yield compared to that achieved previously using passive separation. The system features high flow rates, 5-30 μL/min plasma collection, with minimal clogging and biofouling. The simple, portable blood plasma separation design is hand-driven and can easily be incorporated with microfluidic or laboratory scale diagnostic assays. The separation system was applied to a paper-based diagnostic test for malaria that produced an amplified color change in the presence of Plasmodium falciparum histidine-rich protein 2 at a concentration well below clinical relevancy for undiluted whole blood. PMID:27366819

  8. 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. PMID:27093085

  9. 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.

  10. 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