Genetics Home Reference: ring chromosome 14 syndrome

MedlinePlus

... Support Group) Chromosome Disorder Outreach Citizens United for Research ... Giustina E, Zollino M, Neri G, Gobbi G. Epilepsy in ring 14 syndrome: a clinical and EEG study of 22 patients. Epilepsia. 2013 Dec;54(12): ...

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

Lipoinjection and Multiple Internal Cuts for Congenital Constriction Bands: A New Treatment Approach.

PubMed

Castro-Govea, Yanko; Vela-Martinez, Amin; Treviño-Garcia, Luis Alberto

2017-04-01

Traditional treatment for a congenital constriction band of the limb involves multiple Z-plasties and W-plasties. We propose an alternative surgical procedure for the treatment of congenital constriction bands that obviates the need for Z-plasties and eliminates the constriction band. We present the case of a 36-year-old woman with a congenital constriction band of the leg. Using a minimally invasive approach, the skin segment that included the band was dissected from the deep tissues. Afterwards, multiple slices were performed on the internal surface of the fibrous ring. This and lipoinjection were used to reverse the depression that characterizes the "hourglass sign" and homogenize the skin surface. Results have remained stable in a follow-up period of 18 months. This surgical alternative can be considered as an option for the treatment of congenital constriction bands. It is a safe, reproducible procedure that does not cause additional scars and has good functional and aesthetic results. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Prevalent hallucinations during medical internships: phantom vibration and ringing syndromes.

PubMed

Lin, Yu-Hsuan; Lin, Sheng-Hsuan; Li, Peng; Huang, Wei-Lieh; Chen, Ching-Yen

2013-01-01

Phantom vibration syndrome is a type of hallucination reported among mobile phone users in the general population. Another similar perception, phantom ringing syndrome, has not been previously described in the medical literature. A prospective longitudinal study of 74 medical interns (46 males, 28 females; mean age, 24.8±1.2 years) was conducted using repeated investigations of the prevalence and associated factors of phantom vibration and ringing. The accompanying symptoms of anxiety and depression were evaluated with the Beck Anxiety and Depression Inventories before the internship began, and again at the third, sixth, and twelfth internship months, and two weeks after the internship ended. The baseline prevalence of phantom vibration was 78.1%, which increased to 95.9% and 93.2% in the third and sixth internship months. The prevalence returned to 80.8% at the twelfth month and decreased to 50.0% 2 weeks after the internship ended. The baseline prevalence of phantom ringing was 27.4%, which increased to 84.9%, 87.7%, and 86.3% in the third, sixth, and twelfth internship months, respectively. This returned to 54.2% two weeks after the internship ended. The anxiety and depression scores also increased during the internship, and returned to baseline two weeks after the internship. There was no significant correlation between phantom vibration/ringing and symptoms of anxiety or depression. The incidence of both phantom vibration and ringing syndromes significantly increased during the internship, and subsequent recovery. This study suggests that phantom vibration and ringing might be entities that are independent of anxiety or depression during evaluation of stress-associated experiences during medical internships.

Prevalent Hallucinations during Medical Internships: Phantom Vibration and Ringing Syndromes

PubMed Central

Lin, Yu-Hsuan; Lin, Sheng-Hsuan; Li, Peng; Huang, Wei-Lieh; Chen, Ching-Yen

2013-01-01

Background Phantom vibration syndrome is a type of hallucination reported among mobile phone users in the general population. Another similar perception, phantom ringing syndrome, has not been previously described in the medical literature. Methods A prospective longitudinal study of 74 medical interns (46 males, 28 females; mean age, 24.8±1.2 years) was conducted using repeated investigations of the prevalence and associated factors of phantom vibration and ringing. The accompanying symptoms of anxiety and depression were evaluated with the Beck Anxiety and Depression Inventories before the internship began, and again at the third, sixth, and twelfth internship months, and two weeks after the internship ended. Results The baseline prevalence of phantom vibration was 78.1%, which increased to 95.9% and 93.2% in the third and sixth internship months. The prevalence returned to 80.8% at the twelfth month and decreased to 50.0% 2 weeks after the internship ended. The baseline prevalence of phantom ringing was 27.4%, which increased to 84.9%, 87.7%, and 86.3% in the third, sixth, and twelfth internship months, respectively. This returned to 54.2% two weeks after the internship ended. The anxiety and depression scores also increased during the internship, and returned to baseline two weeks after the internship. There was no significant correlation between phantom vibration/ringing and symptoms of anxiety or depression. The incidence of both phantom vibration and ringing syndromes significantly increased during the internship, and subsequent recovery. Conclusion This study suggests that phantom vibration and ringing might be entities that are independent of anxiety or depression during evaluation of stress-associated experiences during medical internships. PMID:23762302

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

PubMed

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

2005-10-01

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

Management of the Amniotic Band Syndrome with Cleft Palate: Literature Review and Report of a Case

PubMed Central

Cortez-Ortega, Carolina; Flores-Velázquez, Joselín; Ruiz-Rodríguez, Socorro; Noyola-Frías, Miguel Ángel; Santos-Díaz, Miguel Ángel

2017-01-01

Amniotic Band Syndrome (ABS) is a group of congenital malformations that includes the majority of typical constriction rings and limb and digital amputations, together with major craniofacial, thoracic, and abdominal malformations. The syndrome is caused by early rupture of the amniotic sac. Some of the main oral manifestations include micrognathia, hyperdontia, and cleft lip with or without cleft palate, which is present in 14.6% of patients with this syndrome. The purpose of this report was to describe the clinical characteristics and the oral treatment provided to a 6-month-old male patient affected with ABS with cleft lip and palate. PMID:28246561

Distinct 15q Genotypes in Russell-Silver and Ring 15 Syndromes

PubMed Central

Rogan, Peter K.; Seip, James R.; Driscoll, Daniel J.; Papenhausen, Peter R.; Johnson, Virginia P.; Raskin, Salmo; Woodward, Amy L.; Butler, Merlin G.

2018-01-01

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 patients 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. In fact, unequal representation of chromosome 15 alleles in 1 patient with r(15) suggests the possibility that a mosaic karyotype composed of the constitutional cell line and cell line(s) possibly deficient in the ring chromosome might be present. 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. PMID:8779316

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

A node organization in the actomyosin contractile ring generates tension and aids stability

PubMed Central

Thiyagarajan, Sathish; Wang, Shuyuan; O’Shaughnessy, Ben

2017-01-01

During cytokinesis, a contractile actomyosin ring constricts and divides the cell in two. How the ring marshals actomyosin forces to generate tension is not settled. Recently, a superresolution microscopy study of the fission yeast ring revealed that myosins and formins that nucleate actin filaments colocalize in plasma membrane-anchored complexes called nodes in the constricting ring. The nodes move bidirectionally around the ring. Here we construct and analyze a coarse-grained mathematical model of the fission yeast ring to explore essential consequences of the recently discovered ring ultrastructure. The model reproduces experimentally measured values of ring tension, explains why nodes move bidirectionally, and shows that tension is generated by myosin pulling on barbed-end-anchored actin filaments in a stochastic sliding-filament mechanism. This mechanism is not based on an ordered sarcomeric organization. We show that the ring is vulnerable to intrinsic contractile instabilities, and protection from these instabilities and organizational homeostasis require both component turnover and anchoring of components to the plasma membrane. PMID:28954859

Cathode-constriction and column-constriction in high current vacuum arcs subjected to an axial magnetic field

NASA Astrophysics Data System (ADS)

Zhang, Zaiqin; Ma, Hui; Liu, Zhiyuan; Geng, Yingsan; Wang, Jianhua

2018-04-01

The influence of the applied axial magnetic field on the current density distribution in the arc column and electrodes is intensively studied. However, the previous results only provide a qualitative explanation, which cannot quantitatively explain a recent experimental data on anode current density. The objective of this paper is to quantitatively determine the current constriction subjected to an axial magnetic field in high-current vacuum arcs according to the recent experimental data. A magnetohydrodynamic model is adopted to describe the high current vacuum arcs. The vacuum arc is in a diffuse arc mode with an arc current ranged from 6 kArms to 14 kArms and an axial magnetic field ranged from 20 mT to 110 mT. By a comparison of the recent experimental work of current density distribution on the anode, the modelling results show that there are two types of current constriction. On one hand, the current on the cathode shows a constriction, and this constriction is termed as the cathode-constriction. On the other hand, the current constricts in the arc column region, and this constriction is termed as the column-constriction. The cathode boundary is of vital importance in a quantitative model. An improved cathode constriction boundary is proposed. Under the improved boundary, the simulation results are in good agreement with the recent experimental data on the anode current density distribution. It is demonstrated that the current density distribution at the anode is sensitive to that at the cathode, so that measurements of the anode current density can be used, in combination with the vacuum arc model, to infer the cathode current density distribution.

Pericardial constriction after cardiac transplantation.

PubMed

Bansal, Ramesh; Perez, Leandro; Razzouk, Anees; Wang, Nan; Bailey, Leonard

2010-03-01

In this study we present a series of 5 cases that developed constrictive pericarditis after orthotopic heart transplantation. All 5 patients had pericardial effusion of non-infectious etiology in the early post-transplant period. They subsequently presented with heart failure unresponsive to standard medical management. The diagnosis was made by comprehensive echo-Doppler studies. Findings were confirmed at surgical inspection and complete pericardiectomy led to improvement in hemodynamics in 4 patients. One patient had relief from constriction but died of non-cardiac complications. One patient with constriction has been re-listed for transplantation due to intermittent heart block and associated cardiac allograft vasculopathy. Early diagnosis of pericardial constriction after orthotopic heart transplantation requires a high index of clinical suspicion and optimal use of Doppler echocardiography. Early diagnosis and timely surgical pericardiectomy may correct this condition entirely and result in satisfactory long-term results.

Pericarditis - constrictive

MedlinePlus

Constrictive pericarditis is long-term (chronic) inflammation of the sac-like covering of the heart (the pericardium) with thickening and scarring. Related conditions include: Bacterial pericarditis Pericarditis Pericarditis ...

A corkscrew model for dynamin constriction

PubMed Central

Mears, Jason A.; Ray, Pampa; Hinshaw, Jenny E.

2007-01-01

SUMMARY Numerous vesiculation processes throughout the eukaryotic cell are dependant on the protein dynamin, a large GTPase that constricts lipid bilayers. We have combined x-ray crystallography and cryo-electron microscopy (cryo-EM) data to generate a coherent model of dynamin-mediated membrane constriction. X-ray structures of mammalian GTPase and pleckstrin homology (PH) domains of dynamin were fit to cryo-EM structures of human ΔPRD dynamin helices bound to lipid in non-constricted and constricted states. Proteolysis and immunogold labeling experiments confirm the topology of dynamin domains predicted from the helical arrays. Based on the fitting, an observed twisting motion of the GTPase, middle and GTPase-effector domains coincides with conformational changes determined by cryo-EM. We propose a corkscrew model for dynamin constriction based on these motions and predict regions of sequence important for dynamin function as potential targets for future mutagenic and structural studies. PMID:17937909

Uncoupling apical constriction from tissue invagination

PubMed Central

Chung, SeYeon; Kim, Sangjoon; Andrew, Deborah J

2017-01-01

Apical constriction is a widely utilized cell shape change linked to folding, bending and invagination of polarized epithelia. It remains unclear how apical constriction is regulated spatiotemporally during tissue invagination and how this cellular process contributes to tube formation in different developmental contexts. Using Drosophila salivary gland (SG) invagination as a model, we show that regulation of folded gastrulation expression by the Fork head transcription factor is required for apicomedial accumulation of Rho kinase and non-muscle myosin II, which coordinate apical constriction. We demonstrate that neither loss of spatially coordinated apical constriction nor its complete blockage prevent internalization and tube formation, although such manipulations affect the geometry of invagination. When apical constriction is disrupted, compressing force generated by a tissue-level myosin cable contributes to SG invagination. We demonstrate that fully elongated polarized SGs can form outside the embryo, suggesting that tube formation and elongation are intrinsic properties of the SG. DOI: http://dx.doi.org/10.7554/eLife.22235.001 PMID:28263180

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.

A node organization in the actomyosin contractile ring generates tension and aids stability.

PubMed

Thiyagarajan, Sathish; Wang, Shuyuan; O'Shaughnessy, Ben

2017-11-07

During cytokinesis, a contractile actomyosin ring constricts and divides the cell in two. How the ring marshals actomyosin forces to generate tension is not settled. Recently, a superresolution microscopy study of the fission yeast ring revealed that myosins and formins that nucleate actin filaments colocalize in plasma membrane-anchored complexes called nodes in the constricting ring. The nodes move bidirectionally around the ring. Here we construct and analyze a coarse-grained mathematical model of the fission yeast ring to explore essential consequences of the recently discovered ring ultrastructure. The model reproduces experimentally measured values of ring tension, explains why nodes move bidirectionally, and shows that tension is generated by myosin pulling on barbed-end-anchored actin filaments in a stochastic sliding-filament mechanism. This mechanism is not based on an ordered sarcomeric organization. We show that the ring is vulnerable to intrinsic contractile instabilities, and protection from these instabilities and organizational homeostasis require both component turnover and anchoring of components to the plasma membrane. © 2017 Thiyagarajan, Wang, and O’Shaughnessy. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

A corkscrew model for dynamin constriction.

PubMed

Mears, Jason A; Ray, Pampa; Hinshaw, Jenny E

2007-10-01

Numerous vesiculation processes throughout the eukaryotic cell are dependent on the protein dynamin, a large GTPase that constricts lipid bilayers. We have combined X-ray crystallography and cryo-electron microscopy (cryo-EM) data to generate a coherent model of dynamin-mediated membrane constriction. GTPase and pleckstrin homology domains of dynamin were fit to cryo-EM structures of human dynamin helices bound to lipid in nonconstricted and constricted states. Proteolysis and immunogold labeling experiments confirm the topology of dynamin domains predicted from the helical arrays. Based on the fitting, an observed twisting motion of the GTPase, middle, and GTPase effector domains coincides with conformational changes determined by cryo-EM. We propose a corkscrew model for dynamin constriction based on these motions and predict regions of sequence important for dynamin function as potential targets for future mutagenic and structural studies.

Mechanics of Constriction during Cell Division: A Variational Approach

PubMed Central

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

2013-01-01

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

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)

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. © 2015. Published by The Company of Biologists Ltd.

Echocardiography: pericardial thickening and constrictive pericarditis.

PubMed

Schnittger, I; Bowden, R E; Abrams, J; Popp, R L

1978-09-01

A total of 167 patients with pericardial thickening noted on M node echocardiography were studied retrospectively. After the echocardiogram, 72 patients underwent cardiac surgery, cardiac catheterization or autopsy for various heart diseases; 96 patients had none of these procedures. In 49 patients the pericardium was directly visualized at surgery or autopsy; 76 percent of these had pericardial thickening or adhesions. In another 8 percent, pericardial adhesions were absent, but no comment had been made about the appearance of the pericardium itself. In the remaining 16 percent, no comment had been made about the pericardium or percardial space. Cardiac catheterization in 64 patients revealed 24 with hemodynamic findings of constrictive pericarditis or effusive constrictive disease. Seven echocardiographic patterns consistent with pericardial adhesions or pericardial thickening are described and related when possible to the subsequent findings at heart surgery or autopsy. The clinical diagnoses of 167 patients with pericardial thickening are presented. The hemodynamic diagnosis of constrictive pericardial disease was associated with the echocardiographic finding of pericardial thickening, but there were no consistent echocardiographic patterns of pericardial thickening diagnostic of constriction. However, certain other echocardiographic abnormalities of left ventricular posterior wall motion and interventricular septal motion and a high E-Fo slope were suggestive of constriction.

The fission yeast cytokinetic contractile ring regulates septum shape and closure

PubMed Central

Thiyagarajan, Sathish; Munteanu, Emilia Laura; Arasada, Rajesh; Pollard, Thomas D.; O'Shaughnessy, Ben

2015-01-01

ABSTRACT During cytokinesis, fission yeast and other fungi and bacteria grow a septum that divides the cell in two. In fission yeast closure of the circular septum hole by the β-glucan synthases (Bgs) and other glucan synthases in the plasma membrane is tightly coupled to constriction of an actomyosin contractile ring attached to the membrane. It is unknown how septum growth is coordinated over scales of several microns to maintain septum circularity. Here, we documented the shapes of ingrowing septum edges by measuring the roughness of the edges, a measure of the deviation from circularity. The roughness was small, with spatial correlations indicative of spatially coordinated growth. We hypothesized that Bgs-mediated septum growth is mechanosensitive and coupled to contractile ring tension. A mathematical model showed that ring tension then generates almost circular septum edges by adjusting growth rates in a curvature-dependent fashion. The model reproduced experimental roughness statistics and showed that septum synthesis sets the mean closure rate. Our results suggest that the fission yeast cytokinetic ring tension does not set the constriction rate but regulates septum closure by suppressing roughness produced by inherently stochastic molecular growth processes. PMID:26240178

The fission yeast cytokinetic contractile ring regulates septum shape and closure.

PubMed

Thiyagarajan, Sathish; Munteanu, Emilia Laura; Arasada, Rajesh; Pollard, Thomas D; O'Shaughnessy, Ben

2015-10-01

During cytokinesis, fission yeast and other fungi and bacteria grow a septum that divides the cell in two. In fission yeast closure of the circular septum hole by the β-glucan synthases (Bgs) and other glucan synthases in the plasma membrane is tightly coupled to constriction of an actomyosin contractile ring attached to the membrane. It is unknown how septum growth is coordinated over scales of several microns to maintain septum circularity. Here, we documented the shapes of ingrowing septum edges by measuring the roughness of the edges, a measure of the deviation from circularity. The roughness was small, with spatial correlations indicative of spatially coordinated growth. We hypothesized that Bgs-mediated septum growth is mechanosensitive and coupled to contractile ring tension. A mathematical model showed that ring tension then generates almost circular septum edges by adjusting growth rates in a curvature-dependent fashion. The model reproduced experimental roughness statistics and showed that septum synthesis sets the mean closure rate. Our results suggest that the fission yeast cytokinetic ring tension does not set the constriction rate but regulates septum closure by suppressing roughness produced by inherently stochastic molecular growth processes. © 2015. Published by The Company of Biologists Ltd.

Toward Defining "Vocal Constriction": Practitioner Perspectives.

PubMed

Lemon-McMahon, Belinda; Hughes, Diane

2018-01-01

This research investigated the terminology used in relation to constriction of the singing voice from a range of practitioner perspectives. It focused on the locality, causes, consequences, management, trends, identification, and vocabulary of constriction. The research aimed to develop a holistic understanding of the term "vocal constriction" from participant experiences and perceptions (N = 10). Data collection occurred through in-depth, semi-structured interviews with a range of voice care professionals. Participants included three professional groups: (1) Ear, Nose, and Throat medical specialists or laryngologists, (2) speech pathologists or speech therapists, and (3) singing teachers. Purposive sampling was used to ensure that the participants from groups 1 and 2 had extensive experience with singers in their practice. The singing teachers were experienced in either classical or contemporary styles, or both. Participant responses highlighted a discrepancy in preferred terminology, with "constriction" being less favored overall. Several anatomical locations were identified including postural, supraglottic (anteroposterior and false fold), articulatory, and in the intrinsic and extrinsic laryngeal musculature; psychological issues were also identified. Primary causes, secondary causes, and influencing factors were identified. Inefficient technique and poor posture or alignment were considered primary causes; similarly, emotion and anxiety or stress were identified as influencing factors by the majority of participants. There was less uniformity in responses regarding other causes. The major findings of this research are the respective participant group distinctions, an uncertainty regarding anteroposterior constriction, and that the location and effects of constriction are individual to the singer and must be considered contextually. A definition is offered, and areas for further research are identified. Copyright © 2018 The Voice Foundation. Published by

Characterization of superconducting nanowire single-photon detector with artificial constrictions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Ling; Liu, Dengkuan; Wu, Junjie

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 themore » relationship between detection efficiency and kinetic inductance and the bias current, confirming the hypothesis that constrictions exist in SNSPDs.« less

A small and active ring X chromosome in a female with features of Kabuki syndrome.

PubMed

Rodríguez, L; Diego-Alvarez, D; Lorda-Sanchez, I; Gallardo, F L; Martínez-Fernández, M L; Arroyo-Muñoz, M E; Martínez-Frías, M L

2008-11-01

A ring X chromosome is found in about 6% of patients with Turner syndrome (TS), often with mosaicism for a 45,X cell line. Patients with this karyotype are reported to have a higher incidence of a more severe phenotype including mental retardation. In fact, some studies have shown a correlation between this severity and the presence or absence of an intact and functional X inactivation center (XIST). However, the phenotype of the individuals with r(X) cannot be entirely defined in terms of their X-inactivation patterns. Nevertheless, a small group of these patients have been described to manifest clinical features reminiscent of the Kabuki syndrome. Here we present a female patient with clinical features resembling Kabuki syndrome and a mos 45,X/46,X,r(X) karyotype. Methylation analyses of polymorphic alleles of the androgen receptor gene showed that both alleles were unmethylated suggesting an active ring chromosome. A specific X chromosome array CGH was performed estimating the size of the ring to be 17 Mb, lacking the XIST gene, and including some genes with possible implications in the phenotype of the patient. Copyright 2008 Wiley-Liss, Inc.

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

NASA Astrophysics Data System (ADS)

Weiss, Robert M.; Otoadese, Eramosele A.; Oren, Ron M.

1995-05-01

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, by itself, imparts cardiac impairment due to abnormalities of ventricular diastolic function. Methods: 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 equals 5) and Group 2 (No CP, N equals 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 equals 7). Group 4 (Nl, N equals 7) consisted of healthy volunteer subjects. Results: Pericardial thickness measurements with cine CT clearly distinguished Group 1 (mean equals 10 +/- 2 mm) from Group 2 (mean equals 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, from all patients without CP. Patients in Group 3 had pericardial thicknesses similar to those in Group 1 (mean equals 9 +/- 1 mm, p equals NS), but had patterns of diastolic ventricular filling that were nearly identical to Group 4 (Nl). Conclusions: The abnormalities of anatomy and ventricular function present in the syndrome of constrictive pericarditis are clearly and decisively identified by cine CT. This allows a reliable distinction

Genetic investigations on 8 patients affected by ring 20 chromosome syndrome

PubMed Central

2010-01-01

Background Mosaic Chromosome 20 ring [r(20)] is a chromosomal disorder associated with a rare syndrome characterized by a typical seizure phenotype, a particular electroclinical pattern, cognitive impairment, behavioural problems and absence of a consistent pattern of dysmorphology. The pathogenic mechanism underlying seizures disorders in r(20) syndrome is still unknown. We performed a detailed clinical and genetic study on 8 patients with r(20) chromosome, aimed at detecting the genetic mechanism underlying r(20) syndrome. Methods We submitted 8 subjects with a previous diagnosis of ring 20 chromosome mosaicism to a clinical re-evaluation, followed by cytogenetic, FISH, array-CGH and molecular analyses. The genetic study was also extended to their available parents. Results FISH and array-CGH experiments indicate that cryptic deletions on chromosome 20 are not the cause of the r(20) chromosome associated disease. Moreover, no evidence of chromosome 20 uniparental disomy was found. Analysis of FISH signals given by variant in size alphoid tandem repeats probes on the normal chromosome 20 and the r(20) chromosome in the mosaic carriers suggests that the r(20) chromosome is the same chromosome not circularized in the "normal" cell line. Conclusions Higher percentages of r(20) chromosome cells were observed to be related with precocious age at seizure onset and with resistance to antiepileptic drug treatment. Behavioural problems also seem to be associated with higher percentages of r(20) chromosome cells. Our results suggest that an epigenetic mechanism perturbing the expression of genes close to the telomeric regions, rather than deletion of genes located at the distal 20p and/or 20q regions, may underlie the manifestation of r(20) syndrome. PMID:20939888

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

Guideline recommendations for diagnosis and clinical management of Ring14 syndrome-first report of an ad hoc task force.

PubMed

Rinaldi, Berardo; Vaisfeld, Alessandro; Amarri, Sergio; Baldo, Chiara; Gobbi, Giuseppe; Magini, Pamela; Melli, Erto; Neri, Giovanni; Novara, Francesca; Pippucci, Tommaso; Rizzi, Romana; Soresina, Annarosa; Zampini, Laura; Zuffardi, Orsetta; Crimi, Marco

2017-04-11

Ring chromosome 14 syndrome is a rare chromosomal disorder characterized by early onset refractory epilepsy, intellectual disability, autism spectrum disorder and a number of diverse health issues. The aim of this work is to provide recommendations for the diagnosis and management of persons affected by ring chromosome 14 syndrome based on evidence from literature and experience of health professionals from different medical backgrounds who have followed for several years subjects affected by ring chromosome 14 syndrome. The literature search was performed in 2016. Original papers, meta-analyses, reviews, books and guidelines were reviewed and final recommendations were reached by consensus. Conventional cytogenetics is the primary tool to identify a ring chromosome. Children with a terminal deletion of chromosome 14q ascertained by molecular karyotyping (CGH/SNP array) should be tested secondarily by conventional cytogenetics for the presence of a ring chromosome. Early diagnosis should be pursued in order to provide medical and social assistance by a multidisciplinary team. Clinical investigations, including neurophysiology for epilepsy, should be performed at the diagnosis and within the follow-up. Following the diagnosis, patients and relatives/caregivers should receive regular care for health and social issues. Epilepsy should be treated from the onset with anticonvulsive therapy. Likewise, feeding difficulties should be treated according to need. Nutritional assessment is recommended for all patients and nutritional support for malnourishment can include gastrostomy feeding in selected cases. Presence of autistic traits should be carefully evaluated. Many patients with ring chromosome 14 syndrome are nonverbal and thus maintaining their ability to communicate is always essential; every effort should be made to preserve their autonomy.

[Constricted ear therapy with free auricular composite grafts].

PubMed

Liu, Tun; Zhang, Lian-sheng; Zhuang, Hong-xing; Zhang, Ke-yuan

2004-03-01

A simple and effective therapy for single side constricted ear. Transplanting normal side free composite auricular grafts to constricted ear (15 patients and 15 sides), then lengthening the helix, exposing the scapha, correcting deformity. The 15 patients composite grafts all survived. The helix has been lengthened, the scapha exposed, the normal ear reduced, the constricted ear augmented and two sides ear have become symmetry. This method is simple and results are satisfied.

Serial imaging and structure-function correlates of high-density rings of fundus autofluorescence in retinitis pigmentosa.

PubMed

Robson, Anthony G; Tufail, Adnan; Fitzke, Fred; Bird, Alan C; Moore, Anthony T; Holder, Graham E; Webster, Andrew R

2011-09-01

To document the evolution and functional and structural significance of parafoveal rings of high-density fundus autofluorescence (AF) in patients with retinitis pigmentosa and preserved visual acuity. Fifty-two patients with nonsyndromic retinitis pigmentosa or Usher syndrome, who had a parafoveal ring of high-density AF and a visual acuity of 20/30 or better, were ascertained. All had international standard full-field electroretinography and pattern electroretinography. Autofluorescence imaging was repeated in 30 patients after periods of up to 9.3 years. Of the 52 patients, 35 underwent optical coherence tomography. Progressive constriction of the ring was detected in 17 patients. Ring radius reduced by up to 40% at a mean rate of between 0.8% and 15.8% per year. In 1 patient, a small ring was replaced by irregular AF; visual acuity deteriorated over the same period. There was a high correspondence between the lateral extent of the preserved optical coherence tomography inner segment/outer segment band and the diameter of the ring along the same optical coherence tomographic scan plane (slope, 0.9; r = 0.97; P < 0.005; n = 35) and between preserved inner segment/outer segment lamina and the pattern electroretinography P50 measure of macular function (R = 0.72; P < 0.005; n = 34). Rings of increased AF surround areas of preserved outer retina and preserved photopic function. Serial fundus AF may provide prognostic indicators for preservation of central acuity and potentially assist in the identification and evaluation of patients suitable for treatment aimed at preservation of remaining function.

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

NASA Astrophysics Data System (ADS)

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

2016-11-01

Mechanical stress plays an intricate role in gene expression in individual cells and sculpting of developing tissues. 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.

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. Wiley Periodicals, Inc. © 2016 International League Against Epilepsy.

Minimally Invasive Transverse Aortic Constriction in Mice.

PubMed

Zaw, Aung Moe; Williams, Connor M; Law, Helen K W; Chow, Billy Kwok Chong

2017-03-14

Minimally invasive transverse aortic constriction (MTAC) is a more desirable method for the constriction of the transverse aorta in mice than standard open-chest transverse aortic constriction (TAC). Although transverse aortic constriction is a highly functional method for the induction of high pressure in the left ventricle, it is a more difficult and lengthy procedure due to its use of artificial ventilation with tracheal intubation. TAC is oftentimes also less survivable, as the newer method, MTAC, neither requires the cutting of the ribs and intercostal muscles nor tracheal intubation with a ventilation setup. In MTAC, as opposed to a thoracotomy to access to the chest cavity, the aortic arch is reached through a midline incision in the anterior neck. The thyroid is pulled back to reveal the sternal notch. The sternum is subsequently cut down to the second rib level, and the aortic arch is reached simply by separating the connective tissues and thymus. From there, a suture can be wrapped around the arch and tied with a spacer, and then the sternal cut and skin can be closed. MTAC is a much faster and less invasive way to induce left ventricular hypertension and enables the possibility for high-throughput studies. The success of the constriction can be verified using high-frequency trans-thoracic echocardiography, particularly color Doppler and pulsed-wave Doppler, to determine the flow velocities of the aortic arch and left and right carotid arteries, the dimension of the blood vessels, and the left ventricular function and morphology. A successful constriction will also trigger significant histopathological changes, such as cardiac muscle cell hypertrophy with interstitial and perivascular fibrosis. Here, the procedure of MTAC is described, demonstrating how the resulting flow changes in the carotid arteries can be examined with echocardiography, gross morphology, and histopathological changes in the heart.

A pressure-gradient mechanism for vortex shedding in constricted channels

PubMed Central

Boghosian, M. E.; Cassel, K. W.

2013-01-01

Numerical simulations of the unsteady, two-dimensional, incompressible Navier–Stokes equations are performed for a Newtonian fluid in a channel having a symmetric constriction modeled by a two-parameter Gaussian distribution on both channel walls. The Reynolds number based on inlet half-channel height and mean inlet velocity ranges from 1 to 3000. Constriction ratios based on the half-channel height of 0.25, 0.5, and 0.75 are considered. The results show that both the Reynolds number and constriction geometry have a significant effect on the behavior of the post-constriction flow field. The Navier–Stokes solutions are observed to experience a number of bifurcations: steady attached flow, steady separated flow (symmetric and asymmetric), and unsteady vortex shedding downstream of the constriction depending on the Reynolds number and constriction ratio. A sequence of events is described showing how a sustained spatially growing flow instability, reminiscent of a convective instability, leads to the vortex shedding phenomenon via a proposed streamwise pressure-gradient mechanism. PMID:24399860

[Permanent constrictions of the jaws (author's transl)].

PubMed

Dupuis, A; Michaud, J

1981-01-01

Permanent constrictions of the jaws are of various types depending on the site of the lesion: temporomaxillary ankylosis, extra-articular constrictions of bone, skin, muscle, or mucosal origin, and those arising from tumors. The commonest cause is injury, those due to infection being currently less frequently observed, which cannot be said for those of tumoral origin. The consequences are difficulty in taking foud and poor buccodental hygiene, while temporomaxillary ankylosis in children provokes mandibular growth disturbances. Surgical treatment is aimed at removing the constriction. Total resection of the ankylosed block is essential to avoid recurrences, while reeducation of buccal opening must be started early and continued for long periods in all cases.

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

NASA Astrophysics Data System (ADS)

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

2016-10-01

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

[Measurement of cognitive constriction in suicide notes].

PubMed

Heinrich, Monika; Berzlanovich, Andrea; Willinger, Ulrike; Eisenwort, Brigitte

2008-01-01

The target of this paper was to quantify the amount of cognitive constriction in German-language suicide notes by studying quantitative psycholinguistic parameters of texts. This should give a better understanding of presuicidal events and encourage improvement in the field of suicide prevention and crisis intervention. The study is based on letters of the "Vienna Corpus of Suicide Notes". To prove various hypotheses a factor analysis, a number of regression analyses, and the General Linear Model were applied, apart from descriptive methods. The 16 parameters could be reduced to five factors of cognitive constriction, such as the writing style, the usage of words, the dichotomy, the length and the grammatical correctness of the suicide notes. Regarding the writing style the highest values of cognitive constriction were found among women (p=0.005), young persons (p< or =0.000), in short letters (p=0.027) and if psychological problems were the motive for suicide (p=0.020). The discovery site of the letters (p=0.002) was important as well. The construct of cognitive constriction is a multidimensional and complex phenomenon. Therefore the quantification must contain variables of the persons and the texts.

Unconventional transport in ultraclean graphene constriction devices

NASA Astrophysics Data System (ADS)

Pita Vidal, Marta; Ma, Qiong; Watanabe, Kenji; Taniguchi, Takashi; Jarillo-Herrero, Pablo

Under mesoscopic conditions, strong electron-electron interactions and weak electron-phonon coupling in graphene lead to hydrodynamic behavior of electrons, resulting in unusual and unexpected transport phenomena. Specifically, this hydrodynamical collective cooperation of electrons is predicted to enhance the flow of electrical current, leading to a striking higher-than-ballistic conductance through a narrow geometrical constriction. To access the hydrodynamic regime, we fabricated high-quality, low-disorder graphene nano-constriction devices encapsulated by hexagonal boron nitride, where electron-electron scattering dominates impurity scattering. We will report on our systematic four-probe conductance measurements on devices with different constriction widths as a function of number density and temperature. The observation of quantum transport phenomena that are inconsistent with the non-interacting ballistic free-fermion model would suggest a macroscopic transport signature of electron viscosity.

A dimensional approach to the phantom vibration and ringing syndrome during medical internship.

PubMed

Lin, Yu-Hsuan; Chen, Ching-Yen; Li, Peng; Lin, Sheng-Hsuan

2013-09-01

Phantom vibrations and ringing of mobile phones are prevalent hallucinations in the general population. They might be considered as a "normal" brain mechanism. The aim of this study was to determine if a dimensional approach to identify individuals suffering from these hallucinations was more important than a categorical approach. A prospective longitudinal study of 74 medical interns (male: 46, mean age: 24.8 ± 1.2) was carried out using repeated investigations of the severity of phantom vibrations and ringing, as well as accompanying symptoms of anxiety and depression as measured by Beck Anxiety Inventory (BAI) and the Beck Depression Inventory (BDI) before, at the 3rd, 6th, and 12th month during internship, and 2 weeks after internship. We utilized the cognitive and somatic subscales of the BDI, as well as the subjective, somatic and panic subscales of the BAI. The correlation between phantom vibration and ringing was lowest before the internship but became moderate during the internship and high 2 weeks after it. Compared to interns with subclinical phantom ringing and vibrations, interns with severe phantom vibrations and ringing had higher subjective and somatic anxiety and somatic depressive scores at any time point throughout the internship. Only interns with severe phantom ringing had more cognitive/affective depression. A dimensional approach to the phantom vibration and ringing syndrome is a powerful way to identify their correlation, as well as their association with anxiety and depression. Copyright © 2013 Elsevier Ltd. All rights reserved.

Superconducting nanoribbon with a constriction: A quantum-confined Josephson junction

NASA Astrophysics Data System (ADS)

Flammia, L.; Zhang, L.-F.; Covaci, L.; Perali, A.; Milošević, M. V.

2018-04-01

Extended defects are known to strongly affect nanoscale superconductors. Here, we report the properties of superconducting nanoribbons with a constriction formed between two adjacent step edges by solving the Bogoliubov-de Gennes equations self-consistently in the regime where quantum confinement is important. Since the quantum resonances of the superconducting gap in the constricted area are different from the rest of the nanoribbon, such constriction forms a quantum-confined S-S'-S Josephson junction, with a broadly tunable performance depending on the length and width of the constriction with respect to the nanoribbon, and possible gating. These findings provide an intriguing approach to further tailor superconducting quantum devices where Josephson effect is of use.

Gender and Racial Disparities in Life-Space Constriction Among Older Adults.

PubMed

Choi, Moon; O'Connor, Melissa L; Mingo, Chivon A; Mezuk, Briana

2016-12-01

"Life-space" is the spatial area through which a person experiences and interacts with the world. Life-space constriction, the shrinking of the spatial area that a person traverses, is associated with negative health outcomes in later life. Racial and gender disparities in mobility as indicated by life-space constriction are thought to contribute to broader disparities in health and functioning among older adults. Data come from the 5-year follow-up of the Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE) Study (N = 2,765; mean age = 73.6; 75.8% women; 73.7% White). Life-space constriction was defined as "not traveling beyond one's town." A series of logistic regression and Cox proportional hazard models were used to estimate risk for incident life-space constriction by race and gender. Blacks and women had greater likelihood of life-space constriction at baseline. Women were more likely to experience incident life-space constriction at follow-up relative to men (Hazard ratio [HR]: 1.89, 95% Confidence interval [CI]: 1.26-2.83). Blacks were associated with lower risk of life-space constriction over time (HR: 0.67, 95% CI: 0.45-0.99) relative to Whites. Disparities in life-space constriction by gender and race exist in later life. Understanding the processes underlying these mobility restrictions is important to developing intervention programs to enhance health and functioning for older adults. © The Author 2015. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

FtsZ ring: the eubacterial division apparatus conserved in archaebacteria.

PubMed

Wang, X; Lutkenhaus, J

1996-07-01

FtsZ is a tubulin-like protein that is essential for cell division in eubacteria. It functions by forming a ring at the division site that directs septation. The archaebacteria constitute a kingdom of life separate from eubacteria and eukaryotes. Like eubacteria, archaebacteria are prokaryotes, although they are phylogenetically closer to eukaryotes. Here it is shown that archaebacteria also possess FtsZ and that it is biochemically similar to eubacterial FtsZs. Significantly, FtsZ from the archaebacterium Haloferax volcanii is a GTPase that is localized to a ring that coincides with the division constriction. These results indicate that the FtsZ ring was part of the division apparatus of a common prokaryotic ancestor that was retained by both eubacteria and archaebacteria.

Constrictive (obliterative) bronchiolitis.

PubMed

Schlesinger, C; Veeraraghavan, S; Koss, M N

1998-09-01

Constrictive bronchiolitis (CB), also termed in lung transplant patients obliterative bronchiolitis, is inflammation and fibrosis occurring predominantly in the walls and contiguous tissues of membranous and respiratory bronchioles with resultant narrowing of their lumens. CB is found in a variety of settings, most often as a complication of lung and heart-lung transplantation (affecting 34% to 39% of patients, usually in the first 2 years after transplantation) and bone marrow transplantation, but also in rheumatoid arthritis, after inhalation of toxic agents such as nitrogen dioxide, after ingestion of certain drugs such as penicillamine and ingestion of the East Asian vegetable Sauropus androgynous, and as a rare complication of adenovirus, influenza type A, measles, and Mycoplasma pneumoniae infections in children. In lung transplants, CB is the single most important factor leading to death thereafter. In one study, the overall mortality rate was 25%. However, at the same time, 87% of patients who were asymptomatic and diagnosed solely by transbronchial biopsy had resolution or stabilization of disease. Decreases in FEV1 from baseline can be used to clinically support CB in transplant patients; the term bronchiolitis obliterans syndrome is used to denote this clinical dysfunction, and a grading system has been established for it that is now widely used in the literature. Significant risk factors for the development of CB in lung transplants include alloantigen-dependent and -independent mechanisms. In the former group are late acute rejection and HLA mismatches at the A loci; in the latter are ischemia/reperfusion injuries to airways that result from the transplantation surgery and cytomegalovirus infection.

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. © 2016 Wiley Periodicals, Inc.

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

PubMed Central

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

1981-01-01

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

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.

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. Copyright © 2016 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

Molecular organization of cytokinesis nodes and contractile rings by super-resolution fluorescence microscopy of live fission yeast

PubMed Central

Laplante, Caroline; Huang, Fang; Tebbs, Irene R.; Bewersdorf, Joerg; Pollard, Thomas D.

2016-01-01

Cytokinesis in animals, fungi, and amoebas depends on the constriction of a contractile ring built from a common set of conserved proteins. Many fundamental questions remain about how these proteins organize to generate the necessary tension for cytokinesis. Using quantitative high-speed fluorescence photoactivation localization microscopy (FPALM), we probed this question in live fission yeast cells at unprecedented resolution. We show that nodes, protein assembly precursors to the contractile ring, are discrete structural units with stoichiometric ratios and distinct distributions of constituent proteins. Anillin Mid1p, Fes/CIP4 homology-Bin/amphiphysin/Rvs (F-BAR) Cdc15p, IQ motif containing GTPase-activating protein (IQGAP) Rng2p, and formin Cdc12p form the base of the node that anchors the ends of myosin II tails to the plasma membrane, with myosin II heads extending into the cytoplasm. This general node organization persists in the contractile ring where nodes move bidirectionally during constriction. We observed the dynamics of the actin network during cytokinesis, starting with the extension of short actin strands from nodes, which sometimes connected neighboring nodes. Later in cytokinesis, a broad network of thick bundles coalesced into a tight ring around the equator of the cell. The actin ring was ∼125 nm wide and ∼125 nm thick. These observations establish the organization of the proteins in the functional units of a cytokinetic contractile ring. PMID:27647921

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.

Active elastohydrodynamics of vesicles in narrow blind constrictions

NASA Astrophysics Data System (ADS)

Fai, T. G.; Kusters, R.; Harting, J.; Rycroft, C. H.; Mahadevan, L.

2017-11-01

Fluid-resistance limited transport of vesicles through narrow constrictions is a recurring theme in many biological and engineering applications. Inspired by the motor-driven movement of soft membrane-bound vesicles into closed neuronal dendritic spines, here we study this problem using a combination of passive three-dimensional simulations and a simplified semianalytical theory for the active transport of vesicles forced through constrictions by molecular motors. We show that the motion of these objects is characterized by two dimensionless quantities related to the geometry and to the strength of forcing relative to the vesicle elasticity. We use numerical simulations to characterize the transit time for a vesicle forced by fluid pressure through a constriction in a channel and find that relative to an open channel, transport into a blind end leads to the formation of a smaller forward-flowing lubrication layer that strongly impedes motion. When the fluid pressure forcing is complemented by forces due to molecular motors that are responsible for vesicle trafficking into dendritic spines, we find that the competition between motor forcing and fluid drag results in multistable dynamics reminiscent of the real system. Our study highlights the role of nonlocal hydrodynamic effects in determining the kinetics of vesicular transport in constricted geometries.

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.

Nonmedially assembled F-actin cables incorporate into the actomyosin ring in fission yeast

PubMed Central

Huang, Junqi; Huang, Yinyi; Yu, Haochen; Subramanian, Dhivya; Padmanabhan, Anup; Thadani, Rahul; Tao, Yaqiong; Tang, Xie; Wedlich-Soldner, Roland

2012-01-01

In many eukaryotes, cytokinesis requires the assembly and constriction of an actomyosin-based contractile ring. Despite the central role of this ring in cytokinesis, the mechanism of F-actin assembly and accumulation in the ring is not fully understood. In this paper, we investigate the mechanism of F-actin assembly during cytokinesis in Schizosaccharomyces pombe using lifeact as a probe to monitor actin dynamics. Previous work has shown that F-actin in the actomyosin ring is assembled de novo at the division site. Surprisingly, we find that a significant fraction of F-actin in the ring was recruited from formin-Cdc12p nucleated long actin cables that were generated at multiple nonmedial locations and incorporated into the ring by a combination of myosin II and myosin V activities. Our results, together with findings in animal cells, suggest that de novo F-actin assembly at the division site and directed transport of F-actin cables assembled elsewhere can contribute to ring assembly. PMID:23185032

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.

Subacute constrictive pericarditis from Serratia marcescens bacteremia.

PubMed

Khan, M Y

1983-12-01

A case report of subacute constrictive pericarditis associated with disseminated Serratia marcescens infection and bacteremia in a patient with chronic tubulointerstitial nephritis and uremia is described. Although not substantiated by clinical history, the renal pathologic features were similar to those of ethylene glycol-induced tubulointerstitial nephritis. The patient did not have a history of heroin addiction. The importance of predisposing factors such as uremia, invasive vascular procedures, tracheal intubation, peritoneal dialysis, and pericardiocentesis in Serratia infection in susceptible persons is discussed, as are possible roles of uremia, pericardiocentesis, and pericardiotomy in the pathogenesis of constrictive pericarditis in the present case.

Shooting quasiparticles from Andreev bound states in a superconducting constriction

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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 asymmetrymore » 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.« less

Correction of aortic insufficiency with an external adjustable prosthetic aortic ring.

PubMed

Gogbashian, Andrew; Ghanta, Ravi K; Umakanthan, Ramanan; Rangaraj, Aravind T; Laurence, Rita G; Fox, John A; Cohn, Lawrence H; Chen, Frederick Y

2007-09-01

Less invasive, valve-sparing options are needed for patients with aortic insufficiency (AI). We sought to evaluate the feasibility of reducing AI with an external adjustable aortic ring in an ovine model. To create AI, five sheep underwent patch plasty enlargement of the aortic annulus and root by placement of a 10 x 15 mm pericardial patch between the right and noncoronary cusps. An adjustable external ring composed of a nylon band was fabricated and placed around the aortic root. Aortic flow, aortic pressure, and left ventricular pressures were measured with the ring loose (off) and tightened (on). Mean regurgitant orifice area decreased by 86%, from 0.07 +/- 0.03 cm2 (ring loose, off) to 0.01 +/- 0.00 cm2 (ring tightened, on) [p < 0.01]. The regurgitant fraction decreased from 18 +/- 4% to 2 +/- 1% [p < 0.01]. The ring did not significantly affect stroke volume and aortic pressure. An ovine model of aortic root dilatation resulting in acute AI has been developed. In this model, application of an external, adjustable constricting aortic ring eliminated AI. An aortic ring may be a useful adjunct in reducing AI secondary to annular dilatation.

Contractile-Ring Assembly in Fission Yeast Cytokinesis: Recent Advances and New Perspectives

PubMed Central

Lee, I-Ju; Coffman, Valerie C.; Wu, Jian-Qiu

2017-01-01

The fission yeast Schizosaccharomyces pombe is an excellent model organism to study cytokinesis. Here, we review recent advances on contractile-ring assembly in fission yeast. First, we summarize the assembly of cytokinesis nodes, the precursors of a normal contractile ring. IQGAP Rng2 and myosin essential light chain Cdc4 are recruited by the anillin-like protein Mid1, followed by the addition of other cytokinesis node proteins. Mid1 localization on the plasma membrane is stabilized by interphase node proteins. Second, we discuss proteins and processes that contribute to the search, capture, pull, and release mechanism of contractile-ring assembly. Actin filaments nucleated by formin Cdc12, the motor activity of myosin-II, the stiffness of the actin network, and severing of actin filaments by cofilin all play essential roles in contractile-ring assembly. Finally, we discuss the Mid1-independent pathway for ring assembly, and the possible mechanisms underlying the ring maturation and constriction. Collectively, we provide an overview of the current understanding of contractile-ring assembly and uncover future directions in studying cytokinesis in fission yeast. PMID:22887981

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?

Clogging in constricted suspension flows

NASA Astrophysics Data System (ADS)

Marin, Alvaro; Lhuissier, Henri; Rossi, Massimiliano; Kähler, Christian J.

2018-02-01

The flow of a charged-stabilized suspension through a single constricted channel is studied experimentally by tracking the particles individually. Surprisingly, the behavior is found to be qualitatively similar to that of inertial dry granular systems: For small values of the neck-to-particle size ratio (D /d <3 ), clogs form randomly as arches of the particle span the constriction. The statistics of the clogging events are Poissonian as reported for granular systems and agree for moderate particle volume fraction (ϕ ≈20 % ) with a simple stochastic model for the number of particles at the neck. For larger neck sizes (D /d >3 ), even at the largest ϕ (≈60 %) achievable in the experiments, an uninterrupted particle flow is observed, which resembles that of an hourglass. This particularly small value of D /d (≃3 ) at the transition to a practically uninterrupted flow is attributed to the low effective friction between the particles, achieved by the particle's functionalization and lubrication.

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.

Minoxidil accelerates heart failure development in rats with ascending aortic constriction.

PubMed

Turcani, M; Jacob, R

1998-06-01

To test the ability of the heart to express characteristic geometric features of concentric and eccentric hypertrophy concurrently, constriction of the ascending aorta was performed in 4-week-old rats. Simultaneously, these rats were treated with an arteriolar dilator minoxidil. An examination 6 weeks after induction of the hemodynamic overload revealed no signs of congestion in systemic or pulmonary circulation in rats with aortic constriction or minoxidil-treated sham-operated rats. The magnitude of hemodynamic overload caused by aortic constriction or minoxidil treatment could be considered as equivalent, because the same enlargement of left ventricular pressure-volume area was necessary to compensate for either pressure or volume overload. Myocardial contractility decreased in rats with aortic constriction, and the compensation was achieved wholly by the marked concentric hypertrophy. Volume overload in minoxidil-treated rats was compensated partially by the eccentric hypertrophy and partially by the increased myocardial contractility. In contrast, increased lung weight and pleural effusion were found in all minoxidil-treated rats with aortic constriction. Unfavorable changes in left ventricular mass and geometry, relatively high chamber stiffness, and depressed ventricular and myocardial function were responsible for the massive pulmonary congestion.

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

Constrictive (obliterative) bronchiolitis: diagnosis, etiology, and a critical review of the literature.

PubMed

Schlesinger, C; Meyer, C A; Veeraraghavan, S; Koss, M N

1998-10-01

Constrictive bronchiolitis (CB) (or obliterative bronchiolitis) designates inflammation and fibrosis occurring predominantly in the walls and contiguous tissues of membranous and respiratory bronchioles, with resultant narrowing of their lumens. It differs from bronchiolitis obliterans-organizing pneumonia in its histopathology and clinical course. Most cases of CB occur in the setting of organ transplants, particularly lung and heart-lung transplants, but also in bone marrow transplants. Other bona fide cases are rare: infection, particularly viral infection, appears to be a well-documented precursor to CB in children, but not in immunocompetent adults. Constrictive bronchiolitis also has been reported in the course of rheumatoid arthritis, in certain other autoimmune diseases such as pemphigus vulgaris, after inhalation of toxic gases such as nitrogen oxide, after ingestion of certain drugs or medicinal agents such as Sauropus androgynous, and as a cryptogenic illness. Recent reports suggest that CB, as defined by clinical criteria (that is, bronchiolitis obliterans syndrome), is very common in lung allograft recipients who survive more than 5 years and, although it is associated with significant mortality, it also can be clinically stable. Furthermore, with the current practice of close monitoring of these patients, it appears that CB may now be diagnosed at an earlier stage, at which resolution, or at least stabilization of progression, is possible. A histopathologic diagnosis of CB in lung transplant and other patients may be difficult to make due to the patchy distribution of lesions, the technical difficulty in obtaining tissue in late lesions with extensive fibrosis, and the failure to recognize lesions. With regard to the last of these, in early stages of disease, CB may be subtle and easily missed in routine hematoxylin-eosin-stained specimens, while in advanced stages the disease may be equally difficult to diagnose if the patchy scarring in the lung is

The constricted ear.

PubMed

Paredes, Alfredo A; Williams, J Kerwin; Elsahy, Nabil I

2002-04-01

The constricted ear may be described best as a pursestring closure of the ear. The deformity may include lidding of the upper pole with downward folding, protrusion of the concha, decreased vertical height, and low ear position relative to the face. The goals of surgical correction should include obtaining symmetry and correcting the intra-auricular anatomy. The degree of intervention is based on the severity of the deformity and may range from simple repositioning, soft tissue rearrangement, or manipulation of the cartilage. Multiple surgical techniques are described.

Changes in compressed neurons from dogs with acute and severe cauda equina constrictions following intrathecal injection of brain-derived neurotrophic factor-conjugated polymer nanoparticles☆

PubMed Central

Tan, Junming; Shi, Jiangang; Shi, Guodong; Liu, Yanling; Liu, Xiaohong; Wang, Chaoyang; Chen, Dechun; Xing, Shunming; Shen, Lianbing; Jia, Lianshun; Ye, Xiaojian; He, Hailong; Li, Jiashun

2013-01-01

This study established a dog model of acute multiple cauda equina constriction by experimental constriction injury (48 hours) of the lumbosacral central processes in dorsal root ganglia neurons. The repair effect of intrathecal injection of brain-derived neurotrophic factor with 15 mg encapsulated biodegradable poly(lactide-co-glycolide) nanoparticles on this injury was then analyzed. Dorsal root ganglion cells (L7) of all experimental dogs were analyzed using hematoxylin-eosin staining and immunohistochemistry at 1, 2 and 4 weeks following model induction. Intrathecal injection of brain-derived neurotrophic factor can relieve degeneration and inflammation, and elevate the expression of brain-derived neurotrophic factor in sensory neurons of compressed dorsal root ganglion. Simultaneously, intrathecal injection of brain-derived neurotrophic factor obviously improved neurological function in the dog model of acute multiple cauda equina constriction. Results verified that sustained intraspinal delivery of brain-derived neurotrophic factor encapsulated in biodegradable nanoparticles promoted the repair of histomorphology and function of neurons within the dorsal root ganglia in dogs with acute and severe cauda equina syndrome. PMID:25206593

Seronegative rheumatoid arthritis: a rare cause of effusive-constrictive pericarditis requiring pericardiectomy.

PubMed

Soo, Alan; Graham, Alastair

2012-04-01

Effusive-constrictive pericarditis is a rare condition. In this report, we describe a case of effusive-constrictive pericarditis caused by seronegative rheumatoid arthritis which was successfully treated with surgical pericardiectomy.

Droplet squeezing through a narrow constriction: Minimum impulse and critical velocity

NASA Astrophysics Data System (ADS)

Zhang, Zhifeng; Drapaca, Corina; Chen, Xiaolin; Xu, Jie

2017-07-01

Models of a droplet passing through narrow constrictions have wide applications in science and engineering. In this paper, we report our findings on the minimum impulse (momentum change) of pushing a droplet through a narrow circular constriction. The existence of this minimum impulse is mathematically derived and numerically verified. The minimum impulse happens at a critical velocity when the time-averaged Young-Laplace pressure balances the total minor pressure loss in the constriction. Finally, numerical simulations are conducted to verify these concepts. These results could be relevant to problems of energy optimization and studies of chemical and biomedical systems.

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, C.-H.; Lai, Y.-L.

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{submore » 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.« less

Stochastic phase of ventral furrow formation in the Drosophila embryo: cellular constriction chains, mechanical feedback, and robustness

NASA Astrophysics Data System (ADS)

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

The key process giving rise to ventral furrow formation (VFF) in Drosophila embryo is apical constriction of cells in the ventral region. The constriction produces negative spontaneous curvature of the cell layer. During the initial slower phase of VFF approximately 40% of cells constrict in a seemingly random order. We show that this initial phase of VFF does not depend on random uncorrelated events. Instead, constricted cell apices form well-defined correlated structures, i.e., cellular constriction chains (CCCs), indicative of strong spatial and directional correlations between the constriction events. We argue that this chain formation is a signature of mechanical signaling that coordinates apical constrictions through tensile stress. To gain insights into the mechanisms involved in this correlated constriction process, we propose an active granular fluid (AGF) model which considers a tissue as a collection of mechanically active, stress-responsive objects. Our AGF molecular dynamics simulations show that cell constriction sensitivity to tensile stress results in formation of CCCs whereas compressive-stress sensitivity leads to compact constricted cell clusters; the CCCs, which can penetrate less-active regions, increase the robustness of the VFF process.

Contractile-ring assembly in fission yeast cytokinesis: Recent advances and new perspectives.

PubMed

Lee, I-Ju; Coffman, Valerie C; Wu, Jian-Qiu

2012-10-01

The fission yeast Schizosaccharomyces pombe is an excellent model organism to study cytokinesis. Here, we review recent advances on contractile-ring assembly in fission yeast. First, we summarize the assembly of cytokinesis nodes, the precursors of a normal contractile ring. IQGAP Rng2 and myosin essential light chain Cdc4 are recruited by the anillin-like protein Mid1, followed by the addition of other cytokinesis node proteins. Mid1 localization on the plasma membrane is stabilized by interphase node proteins. Second, we discuss proteins and processes that contribute to the search, capture, pull, and release mechanism of contractile-ring assembly. Actin filaments nucleated by formin Cdc12, the motor activity of myosin-II, the stiffness of the actin network, and severing of actin filaments by cofilin all play essential roles in contractile-ring assembly. Finally, we discuss the Mid1-independent pathway for ring assembly, and the possible mechanisms underlying the ring maturation and constriction. Collectively, we provide an overview of the current understanding of contractile-ring assembly and uncover future directions in studying cytokinesis in fission yeast. Copyright © 2012 Wiley Periodicals, Inc.

[Hair-thread tourniquet syndrome].

PubMed

Claudet, I; Pasian, N; Maréchal, C; Salanne, S; Debuisson, C; Grouteau, E

2010-05-01

Describe the epidemiology of tourniquet syndromes and a cohort of such children admitted to the pediatric emergency department (PED), analyze the family's social situation to detect neglect behaviors, and analyze subsequent hospital admissions. From 1st January 2003 to 31st May 2009 in the PED, all patients admitted for tourniquet syndrome were included in the study. The data collected were day and time of admission, age, sex, length of stay, medical coverage, type and location of the constrictive agent, therapeutic management, progression, and complications. PED social workers in relation with child protective services (CPS) recovered information on the family's social situation. During the study period, 57 children were registered. The mean number of admissions per year was 8 (range: 2-15). The mean age was 5.5+/-4 months. The toe was the most frequent location (95%). The penis was injured in 2 cases and labia majora in 1 case. The constrictive agent was often a hair (95%). One case of abuse was detected. The analysis of family social situations showed that 53% had no or incomplete medical coverage, 67% were already followed by CPS with extreme poverty or lived in dilapidated housing. Insufficient hygiene or neglect was found in 67% of the families with incomplete or no social coverage. The analysis of 2003-2007 period for later admissions identified that 15 accidents in the home occurred in 12 children. Among these families, 58% were already known by CPS for neglect behavior. Although most tourniquet syndromes seem accidental, this entity is often associated with a lack of hygiene. Several and distant locations (e.g., toes and genitals), multiple and/or separated knots, constrictive agents inconsistent with a safe environment for the child, and penile location in an infant require meticulous investigation because of a higher incidence of child neglect. Copyright 2010 Elsevier Masson SAS. All rights reserved.

Cardiac magnetic resonance radiofrequency tissue tagging for diagnosis of constrictive pericarditis: A proof of concept study.

PubMed

Power, John A; Thompson, Diane V; Rayarao, Geetha; Doyle, Mark; Biederman, Robert W W

2016-05-01

Invasive cardiac catheterization is the venerable "gold standard" for diagnosing constrictive pericarditis. However, its sensitivity and specificity vary dramatically from center to center. Given the ability to unequivocally define segments of the pericardium with the heart via radiofrequency tissue tagging, we hypothesize that cardiac magnetic resonance has the capability to be the new gold standard. All patients who were referred for cardiac magnetic resonance evaluation of constrictive pericarditis underwent cardiac magnetic resonance radiofrequency tissue tagging to define visceral-parietal pericardial adherence to determine constriction. This was then compared with intraoperative surgical findings. Likewise, all preoperative cardiac catheterization testing was reviewed in a blinded manner. A total of 120 patients were referred for clinical suspicion of constrictive pericarditis. Thirty-nine patients were defined as constrictive pericarditis positive solely via radiofrequency tissue-tagging cardiac magnetic resonance, of whom 21 were positive, 4 were negative, and 1 was equivocal for constrictive pericarditis, as defined by cardiac catheterization. Of these patients, 16 underwent pericardiectomy and were surgically confirmed. There was 100% agreement between cardiac magnetic resonance-defined constrictive pericarditis positivity and postsurgical findings. No patients were misclassified by cardiac magnetic resonance. In regard to the remaining constrictive pericarditis-positive patients defined by cardiac magnetic resonance, 10 were treated medically, declined, were ineligible for surgery, or were lost to follow-up. Long-term follow-up of those who were constrictive pericarditis negative by cardiac magnetic resonance showed no early or late crossover to the surgery arm. Cardiac magnetic resonance via radiofrequency tissue tagging offers a unique, efficient, and effective manner of defining clinically and surgically relevant constrictive pericarditis

Ultrasonographic identification of nerve pathology in neuralgic amyotrophy: Enlargement, constriction, fascicular entwinement, and torsion.

PubMed

Arányi, Zsuzsanna; Csillik, Anita; Dévay, Katalin; Rosero, Maja; Barsi, Péter; Böhm, Josef; Schelle, Thomas

2015-10-01

The aim of this study was to characterize the ultrasonographic findings on nerves in neuralgic amyotrophy. Fourteen patients with neuralgic amyotrophy were examined using high-resolution ultrasound. Four types of abnormalities were found: (1) focal or diffuse nerve/fascicle enlargement (57%); (2) incomplete nerve constriction (36%); (3) complete nerve constriction with torsion (50%; hourglass-like appearance); and (4) fascicular entwinement (28%). Torsions were confirmed intraoperatively and were seen on the radial nerve in 85% of patients. A significant correlation was found between no spontaneous recovery of nerve function and constriction/torsion/fascicular entwinement (P = 0.007). Ultrasonographic nerve pathology in neuralgic amyotrophy varies in order of severity from nerve enlargement to constriction to nerve torsion, with treatment ranging from conservative to surgical. We postulate that the constriction caused by inflammation is the precursor of torsion and that development of nerve torsion is facilitated by the rotational movements of limbs. © 2015 Wiley Periodicals, Inc.

Roles of oxygen radicals and elastase in citric acid-induced airway constriction of guinea-pigs

PubMed Central

Lai, Y -L; Chiou, W -Y; Lu, F J; Chiang, L Y

1999-01-01

Antioxidants attenuate noncholinergic airway constriction. To further investigate the relationship between tachykinin-mediated airway constriction and oxygen radicals, we explored citric acid-induced bronchial constriction in 48 young Hartley strain guinea-pigs, divided into six groups: control; citric acid; hexa(sulphobutyl)fullerenes+citric acid; hexa(sulphobutyl)fullerenes+phosphoramidon+citric acid; dimethylthiourea (DMTU)+citric acid; and DMTU+phosphoramidon+citric acid. Hexa(sulphobutyl)fullerenes and DMTU are scavengers of oxygen radicals while phosphoramidon is an inhibitor of the major degradation enzyme for tachykinins. Animals were anaesthetized, paralyzed, and artificially ventilated. Each animal was given 50 breaths of 4 ml saline or citric acid aerosol. We measured dynamic respiratory compliance (Crs), forced expiratory volume in 0.1 (FEV0.1), and maximal expiratory flow at 30% total lung capacity (V[dot above]max30) to evaluate the degree of airway constriction. Citric acid, but not saline, aerosol inhalation caused marked decreases in Crs, FEV0.1 and V[dot above]max30, indicating marked airway constriction. This constriction was significantly attenuated by either hexa(sulphobutyl)fullerenes or by DMTU. In addition, phosphoramidon significantly reversed the attenuating action of hexa(sulphobutyl)fullerenes, but not that of DMTU. Citric acid aerosol inhalation caused increases in both lucigenin- and t-butyl hydroperoxide-initiated chemiluminescence counts, indicating citric acid-induced increase in oxygen radicals and decrease in antioxidants in bronchoalveolar lavage fluid. These alterations were significantly suppressed by either hexa(sulphobutyl)fullerenes or DMTU. An elastase inhibitor eglin-c also significantly attenuated citric acid-induced airway constriction, indicating the contributing role of elastase in this type of constriction. We conclude that both oxygen radicals and elastase play an important role in tachykinin-mediated, citric acid

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

PubMed

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

2015-01-01

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. To assess the possibility of bone borne transpalatal distraction in pediatric patients. Clinical paper. 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. 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. 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.

Modulation of apical constriction by Wnt signaling is required for lung epithelial shape transition.

PubMed

Fumoto, Katsumi; Takigawa-Imamura, Hisako; Sumiyama, Kenta; Kaneiwa, Tomoyuki; Kikuchi, Akira

2017-01-01

In lung development, the apically constricted columnar epithelium forms numerous buds during the pseudoglandular stage. Subsequently, these epithelial cells change shape into the flat or cuboidal pneumocytes that form the air sacs during the canalicular and saccular (canalicular-saccular) stages, yet the impact of cell shape on tissue morphogenesis remains unclear. Here, we show that the expression of Wnt components is decreased in the canalicular-saccular stages, and that genetically constitutive activation of Wnt signaling impairs air sac formation by inducing apical constriction in the epithelium as seen in the pseudoglandular stage. Organ culture models also demonstrate that Wnt signaling induces apical constriction through apical actomyosin cytoskeletal organization. Mathematical modeling reveals that apical constriction induces bud formation and that loss of apical constriction is required for the formation of an air sac-like structure. We identify MAP/microtubule affinity-regulating kinase 1 (Mark1) as a downstream molecule of Wnt signaling and show that it is required for apical cytoskeletal organization and bud formation. These results suggest that Wnt signaling is required for bud formation by inducing apical constriction during the pseudoglandular stage, whereas loss of Wnt signaling is necessary for air sac formation in the canalicular-saccular stages. © 2017. Published by The Company of Biologists Ltd.

Constrictive Pericarditis 5 Months after Radiation Therapy in a 62-Year-Old Woman with Esophageal Cancer.

PubMed

Yeneneh, Beeletsega T; Allen, Sorcha; Panse, Prasad; Mookadam, Farouk; Rule, William

2017-12-01

Most pericardial changes appear within a few weeks in patients who have undergone radiation therapy for thoracic neoplasms. Chronic pericardial constriction typically occurs decades later, consequent to fibrosis. Early constrictive pericarditis after chest irradiation is quite rare. We report the case of a 62-year-old woman who underwent radiation therapy for esophageal cancer and presented with constrictive pericarditis 5 months later. We searched the English-language medical literature from January 1986 through December 2015 for reports of early constrictive pericarditis after irradiation for thoracic malignancies. We defined "early" as a diagnosis within one year after radiation therapy. Five cases fit our criteria, and we summarize the findings here. To our knowledge, ours is the first definitive report of a patient with esophageal cancer to present with early radiation-induced constrictive pericarditis. We conclude that constrictive pericarditis can occur early after radiation for thoracic malignancies, albeit rarely. When planning care for cancer patients, awareness of this sequela is helpful.

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. Copyright © 2014 Sociedade Portuguesa de Cardiologia. Published by Elsevier España. All rights reserved.

Tunable strength saddle-point contacts impact on quantum rings transmission

NASA Astrophysics Data System (ADS)

González, J. J.; Diago-Cisneros, L.

2016-09-01

A particular subject of investigation is the role of several sadle-point contact (QPC) parameters on the scattering properties of an Aharonov-Bohm-Aharonov-Casher quantum ring (QR) under Rashba-type spin orbit interaction. We discuss the interplay of the conductance with the confinement strengths and height of the QPC, which yields new and tunable harmonic and non-harmonics patterns, while one manipulates these constriction parameters. This phenomenology may be of utility to implement a novel way to modulate spin interference effects in semiconducting QRs, providing an appealing test-platform for spintronics applications.

Role of sensory C fibers in hypoxia/ reoxygenation-impaired myogenic constriction of cerebral arteries

PubMed Central

Xie, Hui; Ray, Patricio E.; Short, Billie Lou

2009-01-01

Objective Hypoxia/reoxygenation (H/R) associated with extracorporeal membrane oxygenation disrupts cerebral autoregulation. However, the underlying mechanisms remain poorly understood. The present study was designed to investigate the role of sensory C-fibers in myogenic responsiveness of cerebral arteries. Methods Arterial diameter and intraluminal pressure were simultaneously measured in vitro on rat posterior cerebral arteries. Results Cerebral arteries constricted in response to graded increase in intraluminal pressure (20–100 mmHg, in 20 mmHg increments). In vitro C-fiber desensitization with capsaicin (1 μmol/l, 20 minutes) significantly suppressed myogenic constriction by over 50%, but did not affect 5-hydroxytryptamine (0.01–10 μmol/l) and KCl (120 mmol/l)-induced constriction. Capsazepine (5 μmol/l, 30 minutes), a selective blocker of neuronal vanilloid receptor TRPV1, had similar inhibitory effect on cerebral myogenic constriction to elevated pressure. Cerebral myogenic constriction was significantly attenuated by H/R; the impairment by H/R was further enhanced after C-fiber desensitization (except at a pressure level of 100 mmHg). Discussion These findings indicate that C-fiber activity contributes to myogenic constriction of cerebral arteries under normal and H/R conditions. H/R-impaired myogenic responsiveness is exaggerated by C-fiber dysfunction. These results raise the possibility that therapeutic strategies directed toward preserving C-fiber nerve endings or supplying its constituent neuropeptides could be developed. PMID:19570322

A new method for correcting type I and type II constricted (cup and lop) ears.

PubMed

Xiaogeng, Hu; Hongxing, Zhuang; Qinghua, Yang; Haiyue, Jiang; Yanyong, Zhao

2006-01-01

Tanzer suggested the term "constricted ear," denoting a spectrum of deformities limited to the superior third of the ear. Tanzer classified the constricted ear into three types. Type I ears have involvement of the helix, which usually is flattened. Type II ears show involvement of both the helix and the scapha. With type III ears, the auricle is rolled into a nearly tubular form that some authors regard as a form of microtia. The authors' new method for correcting the constricted ear varies in accordance with the diverse degree of deformity. The new method was used to correct constricted ears through a one-stage operation in eight type I cases. For the remaining six type 2 cases, the methods were combined with composite grafting. Most of the patients were satisfied with the final results. Therefore, the authors conclude that their approach is suitable for the treatment of type I and type II constricted ears.

Enhancement of allergic skin wheal responses in patients with atopic eczema/dermatitis syndrome by playing video games or by a frequently ringing mobile phone.

PubMed

Kimata, H

2003-06-01

Playing video games causes physical and psychological stress, including increased heart rate and blood pressure and aggression-related feelings. Use of mobile phones is very popular in Japan, and frequent ringing is a common and intrusive part of Japanese life. Atopic eczema/dermatitis syndrome is often exacerbated by stress. Stress increases serum IgE levels, skews cytokine pattern towards Th2 type, enhances allergen-induced skin wheal responses, and triggers mast cell degranulation via substance P, vasoactive intestinal peptide and nerve growth factor. (1). In the video game study, normal subjects (n = 25), patients with allergic rhinitis (n = 25) or atopic eczema/dermatitis syndrome (n = 25) played a video game (STREET FIGHTER II) for 2 h. Before and after the study, allergen-induced wheal responses, plasma levels of substance P, vasoactive intestinal peptide and nerve growth factor, and in vitro production of total IgE, antihouse dust mite IgE and cytokines were measured. (2). In the mobile phone study, normal subjects (n = 27), patients with allergic rhinitis (n = 27) or atopic eczema/dermatitis syndrome (n = 27) were exposed to 30 incidences of ringing mobile phones during 30 min. Before and after the study, allergen-induced wheal responses, plasma levels of substance P, vasoactive intestinal peptide and nerve growth factor were measured. Playing video games had no effect on the normal subjects or the patients with allergic rhinitis. In contrast, playing video games significantly enhanced allergen-induced skin wheal responses and increased plasma levels of substance P, vasoactive intestinal peptide and nerve growth factors in the patients with atopic eczema/dermatitis syndrome. Moreover, playing video games enhanced in vitro production of total IgE and anti-house dust mite IgE with concomitant increased production of IL-4, IL-10 and IL-13 and decreased production of IFN-gamma and IL-12 in the patients with atopic eczema/dermatitis syndrome. However, exposure

A Study on Water Surface Profiles of Rivers with Constriction

NASA Astrophysics Data System (ADS)

Qian, Chaochao; Yamada, Tadashi

2013-04-01

Water surface profile of rivers with constrictions is precious in both classic hydraulics and river management practice. This study was conducted to clarify the essences of the water surface profiles. 3 cases of experiments and 1D numerical calculations with different discharges were made in the study and analysis solutions of the non-linear basic equation of surface profile in varied flow without considering friction were derived. The manning's number was kept in the same in each case by using crosspiece roughness. We found a new type of water surface profile of varied flow from the results of 1D numerical calculation and that of experiments and named it as Mc curve because of its mild condition with constriction segment. This kind of curves appears as a nature phenomenon ubiquitously. The process of water surface forming is dynamic and bore occurs at the upper side of constriction during increasing discharge before the surface profile formed. As a theoretical work, 3 analysis solutions were derived included 2 physical-meaning solutions in the study by using Man-Machine system. One of the derived physical-meaning solutions was confirmed that it is validity by comparing to the results of 1D numerical calculation and that of experiments. The solution represents a flow profile from under critical condition at the upper side to super critical condition at the down side of constriction segment. The other derived physical-meaning solution represents a flow profile from super critical condition at the upper side to under critical condition at the down side of constriction segment. These two kinds of flow profiles exist in the nature but no theoretical solution can express the phenomenon. We find the depth distribution only concerned with unit width discharge distribution and critical depth under a constant discharge from the derived solutions. Therefor, the profile can be gained simply and precisely by using the theoretical solutions instead of numerical calculation even

A de novo atypical ring sSMC(22) characterized by array CGH in a boy with cat-eye syndrome.

PubMed

Haltrich, Irén; Pikó, Henriett; Kiss, Eszter; Tóth, Zsuzsa; Karcagi, Veronika; Fekete, György

2014-01-01

Microduplications 22q11 have been characterized as a genomic duplication syndrome mediated by nonallelic homologous recombination between region-specific low-copy repeats. Here we report on a 19 years old boy with intellectual disability having an unexpected structurally complex ring small supernumerary marker chromosome (sSMC) originated from a larger trisomy and a smaller tetrasomy of proximal 22q11 harboring additional copies of cat eye syndrome critical regions genes. PRINCIPAL CLINICAL FEATURES WERE: anorectal and urogenital malformations, total anomalous pulmonary venous return with secundum ASD, hearing defect, preauricular pits, seizure and eczema. The proband also presented some rare or so far not reported clinical findings such as hyperinsulinaemia, severe immunodeficiency and grave cognitive deficits. Chromosome analysis revealed a mosaic karyotype with the presence of a small ring-like marker in 60% of cells. Array CGH detected approximately an 1,2 Mb single and a 0,2 Mb double copy gain of the proximal long arm of chromosome 22. The 1,3 Mb intervening region of chromosome 22 from centromere to the breakpoints showed no copy alteration. The karyotype of the patient was defined as 47,XY,+mar[60]/46,XY[40].ish idic r(22)(q11.1.q11.21) × 4.arr 22q11(17,435, 645-18,656,678) × 3,(17,598,642-17,799,783) × 4 dn. The present report is the first one with a detailed description of clinical presentation in a patient carrying an atypical size ring sSMC (22) analyzed by array CGH. The specialty of the finding is emphasized by the fact that although the patient had a mosaic sSMC and the amplified region was smaller than in typical cat eye syndrome cases, the clinical presentation was severe.

Sentinel case of group A beta-hemolytic streptococcus causing constrictive pericarditis presenting as hypogammaglobulinemia.

PubMed

Ahmadian, Homayoun R; Tankersley, Michael; Otto, Hans

2011-05-01

This is a unique case of a previously healthy 7-year-old boy, which highlights the importance of considering immunodeficiency when a rare infection occurs. In the following case report, the patient develops constrictive pericarditis secondary to group A beta-hemolytic streptococcal infection. As a result of this infection, we speculate that he develops hypogammaglobulinemia secondary to the documented association between constrictive pericarditis and intestinal lymphangiectasia because an extensive work-up for a primary immunodeficiency was negative. This is the first case ever to present constrictive pericarditis because of group A beta-hemolytic streptococcal infection.

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.

Numerical Simulations of the Motion and Deformation of Three RBCs during Poiseuille Flow through a Constricted Vessel Using IB-LBM.

PubMed

Wang, Rongyang; Wei, Yikun; Wu, Chuanyu; Sun, Liang; Zheng, Wenguang

2018-01-01

The immersed boundary-lattice Boltzmann method (IB-LBM) was used to examine the motion and deformation of three elastic red blood cells (RBCs) during Poiseuille flow through constricted microchannels. The objective was to determine the effects of the degree of constriction and the Reynolds (Re) number of the flow on the physical characteristics of the RBCs. It was found that, with decreasing constriction ratio, the RBCs experienced greater forced deformation as they squeezed through the constriction area compared to at other parts of the microchannel. It was also observed that a longer time was required for the RBCs to squeeze through a narrower constriction. The RBCs subsequently regained a stable shape and gradually migrated toward the centerline of the flow beyond the constriction area. However, a sick RBC was observed to be incapable of passing through a constricted vessel with a constriction ratio ≤1/3 for Re numbers below 0.40.

Numerical Simulations of the Motion and Deformation of Three RBCs during Poiseuille Flow through a Constricted Vessel Using IB-LBM

PubMed Central

Sun, Liang; Zheng, Wenguang

2018-01-01

The immersed boundary-lattice Boltzmann method (IB-LBM) was used to examine the motion and deformation of three elastic red blood cells (RBCs) during Poiseuille flow through constricted microchannels. The objective was to determine the effects of the degree of constriction and the Reynolds (Re) number of the flow on the physical characteristics of the RBCs. It was found that, with decreasing constriction ratio, the RBCs experienced greater forced deformation as they squeezed through the constriction area compared to at other parts of the microchannel. It was also observed that a longer time was required for the RBCs to squeeze through a narrower constriction. The RBCs subsequently regained a stable shape and gradually migrated toward the centerline of the flow beyond the constriction area. However, a sick RBC was observed to be incapable of passing through a constricted vessel with a constriction ratio ≤1/3 for Re numbers below 0.40. PMID:29681999

Constriction of isolated collecting lymphatic vessels in response to acute increases in downstream pressure

PubMed Central

Scallan, Joshua P; Wolpers, John H; Davis, Michael J

2013-01-01

Collecting lymphatic vessels generate pressure to transport lymph downstream to the subclavian vein against a significant pressure head. To investigate their response to elevated downstream pressure, collecting lymphatic vessels containing one valve (incomplete lymphangion) or two valves (complete lymphangion) were isolated from the rat mesentery and tied to glass cannulae capable of independent pressure control. Downstream pressure was selectively raised to various levels, either stepwise or ramp-wise, while keeping upstream pressure constant. Diameter and valve positions were tracked under video microscopy, while intralymphangion pressure was measured concurrently with a servo-null micropipette. Surprisingly, a potent lymphatic constriction occurred in response to the downstream pressure gradient due to (1) a pressure-dependent myogenic constriction and (2) a frequency-dependent decrease in diastolic diameter. The myogenic index of the lymphatic constriction (−3.3 ± 0.6, in mmHg) was greater than that of arterioles or collecting lymphatic vessels exposed to uniform increases in pressure (i.e. upstream and downstream pressures raised together). Additionally, the constriction was transmitted to the upstream lymphatic vessel segment even though it was protected from changes in pressure by a closed intraluminal valve; the conducted constriction was blocked by loading only the pressurized half of the vessel with either ML-7 (0.5 mm) to block contraction, or cromakalim (3 μm) to hyperpolarize the downstream muscle layer. Finally, we provide evidence that the lymphatic constriction is important to maintain normal intraluminal valve closure during each contraction cycle in the face of an adverse pressure gradient, which probably protects the lymphatic capillaries from lymph backflow. PMID:23045335

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.

Effects of channel constriction on upstream steering of flow around Locke Island, Columbia River, Washington

NASA Astrophysics Data System (ADS)

Loy, G. E.; Furbish, D. J.; Covey, A.

2010-12-01

Landsliding of the White Bluffs along the Columbia River in Washington State has constricted the width of the river on one side of Locke Island, a two-kilometer long island positioned in the middle of the channel. Associated changes in flow are thought to be causing relatively rapid erosion of Locke Island on the constricted side. This island is of cultural significance to Native American tribes of south-central Washington, so there are social as well as scientific reasons to understand how the alteration of stream channel processes resulting from the landsliding might be influencing observed erosion rates. Simple hydrodynamic calculations suggest that the constriction on one side of the island creates an upstream backwater effect. As a consequence a cross-stream pressure gradient upstream of the island results in steering of flow around the island into the unobstructed thread. This diversion of water decreases the discharge through the constriction. Therefore, flow velocities within the constriction are not necessarily expected to be higher than those in the unobstructed thread, contrary to initial reports suggesting that higher velocities within the constriction are the main cause of erosion. We set up streamtable experiments with lapse rate imaging to illustrate the backwater effects of the channel constriction and the associated cross-stream steering of flow around a model island. Our experiments are scaled by channel roughness and slope rather than geometrically, as the main focus is to understand the mechanical behavior of flow in this type of island-landslide system. In addition, we studied the stream velocities and flow steering as well as the magnitude of the backwater effect in both the constricted and unobstructed channels using tracer particles in the time-lapse images. These experimental data are compared with calculated upstream backwater distances determined from the known water-surface slope, flow depth, total discharge, and bed roughness

Effects of hawthorn on the progression of heart failure in a rat model of aortic constriction.

PubMed

Hwang, Hyun Seok; Boluyt, Marvin O; Converso, Kimber; Russell, Mark W; Bleske, Barry E

2009-06-01

To determine the effects of hawthorn (Crataegus oxycantha) on left ventricular remodeling and function in pressure overload-induced heart failure in an animal model. Randomized, parallel, dose-ranging animal study. University research facility. Seventy-four male Sprague-Dawley rats; 44 were included in the final analysis. Rats underwent a sham operation or aortic constriction. Rats subjected to the sham operation were treated with vehicle (10% agar-agar), and those subjected to aortic constriction were treated with vehicle or hawthorn (C. oxycantha special extract WS 1442) 1.3, 13, or 130 mg/kg for 5 months. Rats and their hearts were weighed, and echocardiographic measurements were performed at baseline and at 2, 3, 4, and 5 months after aortic constriction. Protein expression for markers of fibrosis and for atrial natriuretic factor was also measured. Aortic constriction increased the left ventricular:body weight ratio by 53% in vehicle-treated rats; Hawthorn treatment did not significantly affect the aortic constriction-induced increase in this ratio. Left ventricular volumes and dimensions at systole and diastole significantly increased 5 months after aortic constriction compared with baseline in rats given vehicle (> 20% increase, p<0.05) but not in those given hawthorn 130 mg/kg (< 10% increase). After aortic constriction, the velocity of circumferential shortening significantly decreased in the vehicle group but not in the medium- or high-dose groups. In the aortic constriction-vehicle group, the induced increases in messenger RNA expression for atrial natriuretic factor (approximately 1000%) and fibronectin (approximately 80%) were significantly attenuated by high-dose hawthorn treatment by approximately 80% and 50%, respectively. Hawthorn treatment exhibited modest beneficial effects on cardiac remodeling and function during long-term, pressure overload-induced heart failure in rats.

Penoscrotal Strangulation Caused by a Steel Ring: A Case Report.

PubMed

Zhang, Jiqing; Wang, Xueming; Li, Zhulin; Zhang, Junhui; Zhang, Xiaodong; Xing, Nianzeng

2017-06-01

Strangulation of the penis and scrotum by a constricting object has been rarely reported. To describe a man with penoscrotal strangulation caused by a steel ring and its successful removal. A 28-year-old man presented to the emergency department with a 7-hour history of a steel ring lodged at the base of his penis and scrotum. Removal was accomplished with the assistance of fire brigade personnel who used their hydraulic cable cutter to shear the ring. During the removal, there were no complications. The hydraulic cable cutter avoided thermal injury and shortened removal time compared with procedures described in the literature. The patient's recovery was uneventful, with erectile function restored after 1 week. Genital incarceration is an urgent clinical situation requiring prompt treatment. However, suitable tools for removing the foreign object are not readily available in emergency and urology departments. Cooperation with other disciplines, even non-medical disciplines, can result in creative and timely measures for removal of the object. Zhang J, Wang X, Zhang J, et al. Penoscrotal Strangulation Caused by a Steel Ring: A Case Report. Sex Med 2017;5:e131-e133. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Sick sinus syndrome as a complication of mediastinal radiation therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pohjola-Sintonen, S.; Toetterman, K.J.K.; Kupari, M.

1990-06-01

A 33-year-old man who had received mediastinal radiation therapy for Hodgkin's disease 12 years earlier developed a symptomatic sick sinus syndrome requiring the implantation of a permanent pacemaker. The sick sinus syndrome and a finding of an occult constrictive pericarditis were considered to be due to the previous mediastinal irradiation. A ventricular pacemaker was chosen because mediastinal radiotherapy also increases the risk of developing atrioventricular conduction defects.

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…

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

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

PubMed

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

2015-11-01

Snakes are important predators that have radiated throughout many ecosystems, and constriction was important in their radiation. Constrictors immobilize and kill prey by using body loops to exert pressure on their prey. Despite its importance, little is known about constriction performance or its full effects on prey. We studied the scaling of constriction performance in two species of giant pythons (Python reticulatus and Python molurus bivittatus) and propose a new mechanism of prey death by constriction. In both species, peak constriction pressure increased significantly with snake diameter. These and other constrictors can exert pressures dramatically higher than their prey's blood pressure, suggesting that constriction can stop circulatory function and perhaps kill prey rapidly by over-pressurizing the brain and disrupting neural function. We propose the latter 'red-out effect' as another possible mechanism of prey death from constriction. These effects may be important to recognize and treat properly in rare cases when constrictors injure humans. © 2015. Published by The Company of Biologists Ltd.

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

NASA Astrophysics Data System (ADS)

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

2016-09-01

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

Pharmacological constriction of the lower oesophageal sphincter: a simple method of arresting variceal haemorrhage.

PubMed Central

Hosking, S W; Doss, W; el-Zeiny, H; Robinson, P; Barsoum, M S; Johnson, A G

1988-01-01

The effect of pharmacological constriction of the lower oesophageal sphincter (LOS) on oesophageal varices was investigated in an experimental study followed by a controlled clinical trial. In the experimental study intravariceal pressure was measured just above the LOS in 11 patients before and after constricting the LOS by intravenous pentagastrin. Intravariceal pressure fell from a mean of 23 (range 12-36) mmHg to 4 (range 0-7) mmHg (p less than 0.001). This marked pressure drop indicated the considerable compression of varices that occurred within the LOS. A prospective controlled clinical trial examined whether LOS constriction (effected by the longer acting metoclopramide) would compress varices sufficiently to arrest active variceal bleeding originating from the lowest 2 cm oesophagus--the area encircled by the LOS. Of 11 patients who received metoclopramide, 10 stopped bleeding compared with four of the 11 who received placebo (p less than 0.01). Pharmacological constriction of the LOS appears to offer a new and effective approach for arresting active bleeding from oesophageal varices. PMID:3044932

A rare combination of amniotic constriction band with osteogenesis imperfecta.

PubMed

Shah, Krupa Hitesh; Shah, Hitesh

2015-11-11

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. 2015 BMJ Publishing Group Ltd.

Myeloid mineralocorticoid receptor deficiency inhibits aortic constriction-induced cardiac hypertrophy in mice.

PubMed

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

2014-01-01

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

Nebulized perflubron and carbon dioxide rapidly dilate constricted airways in an ovine model of allergic asthma.

PubMed

El Mays, Tamer Y; Choudhury, Parichita; Leigh, Richard; Koumoundouros, Emmanuel; Van der Velden, Joanne; Shrestha, Grishma; Pieron, Cora A; Dennis, John H; Green, Francis Hy; Snibson, Ken J

2014-09-16

The low toxicity of perfluorocarbons (PFCs), their high affinity for respiratory gases and their compatibility with lung surfactant have made them useful candidates for treating respiratory diseases such as adult respiratory distress syndrome. We report results for treating acute allergic and non-allergic bronchoconstriction in sheep using S-1226 (a gas mixture containing carbon dioxide and small volumes of nebulized perflubron). The carbon dioxide, which is highly soluble in perflubron, was used to relax airway smooth muscle. Sheep previously sensitized to house dust mite (HDM) were challenged with HDM aerosols to induce early asthmatic responses. At the maximal responses (characterised by an increase in lung resistance), the sheep were either not treated or treated with one of the following; nebulized S-1226 (perflubron + 12% CO2), nebulized perflubron + medical air, 12% CO2, salbutamol or medical air. Lung resistance was monitored for up to 20 minutes after cessation of treatment. Treatment with S-1226 for 2 minutes following HDM challenge resulted in a more rapid, more profound and more prolonged decline in lung resistance compared with the other treatment interventions. Video bronchoscopy showed an immediate and complete (within 5 seconds) re-opening of MCh-constricted airways following treatment with S-1226. S-1226 is a potent and rapid formulation for re-opening constricted airways. Its mechanism(s) of action are unknown. The formulation has potential as a rescue treatment for acute severe asthma.

Mild mitral and tricuspid regurgitation secondary to pericardial constriction.

PubMed

Mittal, S R

2014-06-01

A 26 years female presented with pericardial effusion. On follow up she developed pericardial constriction with new appearance of mild mitral and tricuspid regurgitation without any other pathology. Fibrosis along posterior atrioventricular groove could be responsible for regurgitation.

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

Superoxide constricts rat pulmonary arteries via Rho-kinase-mediated Ca2+ sensitization

PubMed Central

Shaifta, Yasin; Connolly, Michelle; Drndarski, Svetlana; Noah, Anthony; Pourmahram, Ghazaleh E.; Becker, Silke; Aaronson, Philip I.; Ward, Jeremy P.T.

2018-01-01

Reactive oxygen species play a key role in vascular disease, pulmonary hypertension, and hypoxic pulmonary vasoconstriction. We investigated contractile responses, intracellular Ca2+ ([Ca2+]i), Rho-kinase translocation, and phosphorylation of the regulatory subunit of myosin phosphatase (MYPT-1) and of myosin light chain (MLC20) in response to LY83583, a generator of superoxide anion, in small intrapulmonary arteries (IPA) of rat. LY83583 caused concentration-dependent constrictions in IPA and greatly enhanced submaximal PGF2α-mediated preconstriction. In small femoral or mesenteric arteries of rat, LY83583 alone was without effect, but it relaxed a PGF2α-mediated preconstriction. Constrictions in IPA were inhibited by superoxide dismutase and tempol, but not catalase, and were endothelium and guanylate cyclase independent. Constrictions were also inhibited by the Rho-kinase inhibitor Y27632 and the Src-family kinase inhibitor SU6656. LY83583 did not raise [Ca2+]i, but caused a Y27632-sensitive constriction in α-toxin-permeabilized IPA. LY83583 triggered translocation of Rho-kinase from the nucleus to the cytosol in pulmonary artery smooth muscle cells and enhanced phosphorylation of MYPT-1 at Thr-855 and of MLC20 at Ser-19 in IPA. This enhancement was inhibited by superoxide dismutase and abolished by Y27632. Hydrogen peroxide did not activate Rho-kinase. We conclude that in rat small pulmonary artery, superoxide triggers Rho-kinase-mediated Ca2+ sensitization and vasoconstriction independent of hydrogen peroxide. PMID:19103285

MRCK-1 drives apical constriction in C. elegans by linking developmental patterning to force generation

PubMed Central

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

2016-01-01

Summary 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 endodermal 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

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.

Division of constricted and urethane-treated sand dollar eggs: a test of the polar stimulation hypothesis.

PubMed

Rappaport, R; Rappaport, B N

1984-07-01

In spherical cells with a central mitotic apparatus, the centers of the asters are closer to the poles than to the equator. This circumstance is basic to several hypothetical explanations of the way in which the mitotic apparatus establishes the division mechanism. This investigation was designed to determine whether that geometrical relationship is necessary for division. Fertilized, mechanically denuded sand dollar eggs were inserted into glass loops, which reduced the diameter in the constriction plane from the normal 142 to 78-80 microns and partly constricted the cell into equal parts. The mitotic apparatus straddled the constriction, and its length was not significantly changed. The manipulation increased the distance from the astral centers to the poles and decreased the distance from the astral centers to the equator to a degree that reversed the normal distance relations. These cells divided normally. Ethyl urethane (0.06 M) reduces the size of the mitotic apparatus and blocks cleavage in spherical cells. When treated cells are confined in 80-microns i.d. capillaries, they divide. Treated cells also divide when they are constricted by an 80-microns i.d. glass loop if the mitotic apparatus straddles the constriction. An equal degree of constriction in the subfurrow and subpolar areas did not reverse the effect of urethane. The results demonstrate that cleavage does not depend on the normal distance relation between the mitotic apparatus and the poles, and that the urethane effect can be remedied only by reducing the distance between the mitotic apparatus and the equatorial surface. Both findings are inconsistent with the polar stimulation hypothesis.

Clogging Transition of Vibration-Driven Vehicles Passing through Constrictions.

PubMed

Patterson, G A; Fierens, P I; Sangiuliano Jimka, F; König, P G; Garcimartín, A; Zuriguel, I; Pugnaloni, L A; Parisi, D R

2017-12-15

We report experimental results on the competitive passage of elongated self-propelled vehicles rushing through a constriction. For the chosen experimental conditions, we observe the emergence of intermittencies similar to those reported previously for active matter passing through narrow doors. Noteworthy, we find that, when the number of individuals crowding in front of the bottleneck increases, there is a transition from an unclogged to a clogged state characterized by a lack of convergence of the mean clog duration as the measuring time increases. It is demonstrated that this transition-which was reported previously only for externally vibrated systems such as colloids or granulars-appears also for self-propelled agents. This suggests that the transition should also occur for the flow through constrictions of living agents (e.g., humans and sheep), an issue that has been elusive so far in experiments due to safety risks.

Clogging Transition of Vibration-Driven Vehicles Passing through Constrictions

NASA Astrophysics Data System (ADS)

Patterson, G. A.; Fierens, P. I.; Sangiuliano Jimka, F.; König, P. G.; Garcimartín, A.; Zuriguel, I.; Pugnaloni, L. A.; Parisi, D. R.

2017-12-01

We report experimental results on the competitive passage of elongated self-propelled vehicles rushing through a constriction. For the chosen experimental conditions, we observe the emergence of intermittencies similar to those reported previously for active matter passing through narrow doors. Noteworthy, we find that, when the number of individuals crowding in front of the bottleneck increases, there is a transition from an unclogged to a clogged state characterized by a lack of convergence of the mean clog duration as the measuring time increases. It is demonstrated that this transition—which was reported previously only for externally vibrated systems such as colloids or granulars—appears also for self-propelled agents. This suggests that the transition should also occur for the flow through constrictions of living agents (e.g., humans and sheep), an issue that has been elusive so far in experiments due to safety risks.

Role of calcium in the constriction of isolated cerebral arteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 affinitymore » 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.« less

Quantum transport through MoS2 constrictions defined by photodoping.

PubMed

Epping, Alexander; Banszerus, Luca; Güttinger, Johannes; Krückeberg, Luisa; Watanabe, Kenji; Taniguchi, Takashi; Hassler, Fabian; Beschoten, Bernd; Stampfer, Christoph

2018-05-23

We present a device scheme to explore mesoscopic transport through molybdenum disulfide (MoS 2 ) constrictions using photodoping. The devices are based on van-der-Waals heterostructures where few-layer MoS 2 flakes are partially encapsulated by hexagonal boron nitride (hBN) and covered by a few-layer graphene flake to fabricate electrical contacts. Since the as-fabricated devices are insulating at low temperatures, we use photo-induced remote doping in the hBN substrate to create free charge carriers in the MoS 2 layer. On top of the device, we place additional metal structures, which define the shape of the constriction and act as shadow masks during photodoping of the underlying MoS 2 /hBN heterostructure. Low temperature two- and four-terminal transport measurements show evidence of quantum confinement effects.

Quantum transport through MoS2 constrictions defined by photodoping

NASA Astrophysics Data System (ADS)

Epping, Alexander; Banszerus, Luca; Güttinger, Johannes; Krückeberg, Luisa; Watanabe, Kenji; Taniguchi, Takashi; Hassler, Fabian; Beschoten, Bernd; Stampfer, Christoph

2018-05-01

We present a device scheme to explore mesoscopic transport through molybdenum disulfide (MoS2) constrictions using photodoping. The devices are based on van-der-Waals heterostructures where few-layer MoS2 flakes are partially encapsulated by hexagonal boron nitride (hBN) and covered by a few-layer graphene flake to fabricate electrical contacts. Since the as-fabricated devices are insulating at low temperatures, we use photo-induced remote doping in the hBN substrate to create free charge carriers in the MoS2 layer. On top of the device, we place additional metal structures, which define the shape of the constriction and act as shadow masks during photodoping of the underlying MoS2/hBN heterostructure. Low temperature two- and four-terminal transport measurements show evidence of quantum confinement effects.

The role of Rho-kinase and calcium ions in constriction triggered by ET-1.

PubMed

Wiciński, Michał; Szadujkis-Szadurska, Katarzyna; Węclewicz, Mateusz M; Malinowski, Bartosz; Matusiak, Grzegorz; Walczak, Maciej; Wódkiewicz, Eryk; Grześk, Grzegorz; Pawlak-Osińska, Katarzyna

2018-05-05

Endothelin-1 (ET-1) is one of the key factors regulating tension of smooth muscles in blood vessels. It is believed that ET-1 plays an important role in pathogenesis of hypertension, and cardiovascular diseases; therefore, research in order to limit ET-1-mediated action is still in progress. The main objective of this paper was to evaluate the role of Rho-kinase in the ET-1-induced constriction of arteries. The analysis also included significance of intra- and extracellular pool of calcium ions in constriction triggered by ET-1. The studies were performed on perfused Wistar rat tail arteries. Concentration response curve (CRC) was determined for ET-1 in the presence of increased concentrations of Rho-kinase inhibitor (Y-27632) and IP3-receptor antagonist (2APB), both in reference to constriction triggered by solely ET-1. Afterwards, the influence of calcium ions present in the perfusion fluid was evaluated in terms of the effect triggered by 2APB and occurring in arteries constricted by ET-1. ET-1, in concentration dependent manner, leads to increase in perfusion pressure. Y-27632 and 2APB lead to shift of the concentration response curve for ET-1 to the right with simultaneously lowered maximum effect. There was no difference in reaction of the artery constricted by ET-1 and treated with 2APB in solution containing calcium and in calcium-free solution. Vasoconstrictive action of endothelin is not significantly dependent on the inflow of extracellular calcium, but it is proportional to inflow of Ca 2+ related to activation of IP3 receptors and to Rho-kinase activity. Copyright © 2018. Published by Elsevier Inc.

Strategic obstacle placement reduces drop breakup probability in concentrated emulsion flowing into a constriction

NASA Astrophysics Data System (ADS)

Khor, Jian Wei; Hua, Yu; Bick, Alison; Tang, Sindy

2017-11-01

In this study, we investigate the effect of an obstacle on the breakup probability of droplets within a concentrated emulsion flowing into a constriction. We introduce a concentrated emulsion as a 2D monolayer through a tapered channel into a narrow constriction. This geometry is commonly used for the serial interrogation of droplet content in droplet microfluidics applications. We found that certain drop-drop interactions near the constriction entrance lead to the breakup of these drops at a high flow rates. Such breakup sets the upper limit for the droplet interrogation throughput. Incidentally, previous findings have shown that strategic placement of a circular post near a narrow exit can reduce the conflict from the interactions among living organisms (humans, ants, and sheep) or a cluster of particles when entering a narrow exit. Inspired by these results, we modify the tapered channel by placing a circular post in a strategic location near the constriction entrance in order to reduce catastrophic drop-drop interactions and to avoid breakup. Preliminary work shows that the circular posts can reduce the breakup fraction of drops by up to 17%. The optimization of the location and size of the obstacle is expected to further reduce the breakup fraction.

Lymphatic pump treatment increases thoracic duct lymph flow in conscious dogs with edema due to constriction of the inferior vena cava.

PubMed

Prajapati, Parna; Shah, Pankhil; King, Hollis H; Williams, Arthur G; Desai, Pratikkumar; Downey, H Fred

2010-09-01

Osteopathic lymphatic pump treatments (LPT) are used to treat edema, but their direct effects on lymph flow have not been studied. In the current study, we examined the effects of LPT on lymph flow in the thoracic duct of instrumented conscious dogs in the presence of edema produced by constriction of the inferior vena cava (IVC). Six dogs were surgically instrumented with an ultrasonic flow transducer on the thoracic lymph duct and catheters in the descending thoracic aorta and in IVC. After postoperative recovery, lymph flow and hemodynamic variables were measured 1) pre-LPT, 2) during 4 min LPT, 3) post-LPT, in the absence and presence of edema produced by IVC constriction. This constriction increased abdominal girth from 60 +/-2.6 to 75 +/- 2.9 cm. Before IVC constriction, LPT increased lymph flow (P < 0.05) from 1.9 +/- 0.2 ml/min to a maximum of 4.7 +/-1.2 ml/min, whereas after IVC constriction, LPT increased lymph flow (P < 0.05) from 7.9 +/-2.2 to a maximum of 11.7 +/-2.2 ml/min. The incremental lymph flow mobilized by 4 min of LPT (ie, the flow that exceeded 4 min of baseline flow), was 10.6 ml after IVC constriction. This incremental flow was not significantly greater than that measured before IVC constriction. Edema caused by IVC constriction markedly increased lymph flow in the thoracic duct. LPT increased thoracic duct lymph flow before and after IVC constriction. The lymph flow mobilized by 4 min of LPT in presence of edema was not significantly greater than that mobilized prior to edema.

Use of Cardiac Magnetic Resonance Imaging Based Measurements of Inferior Vena Cava Cross-Sectional Area in the Diagnosis of Pericardial Constriction.

PubMed

Hanneman, Kate; Thavendiranathan, Paaladinesh; Nguyen, Elsie T; Moshonov, Hadas; Wald, Rachel; Connelly, Kim A; Paul, Narinder S; Wintersperger, Bernd J; Crean, Andrew M

2015-08-01

To evaluate the value of cardiac magnetic resonance imaging (MRI)-based measurements of inferior vena cava (IVC) cross-sectional area in the diagnosis of pericardial constriction. Patients who had undergone cardiac MRI for evaluation of clinically suspected pericardial constriction were identified retrospectively. The diagnosis of pericardial constriction was established by clinical history, echocardiography, cardiac catheterization, intraoperative findings, and/or histopathology. Cross-sectional areas of the suprahepatic IVC and descending aorta were measured on a single axial steady-state free-precession (SSFP) image at the level of the esophageal hiatus in end-systole. Logistic regression and receiver-operating curve (ROC) analyses were performed. Thirty-six patients were included; 50% (n = 18) had pericardial constriction. Mean age was 53.9 ± 15.3 years, and 72% (n = 26) were male. IVC area, ratio of IVC to aortic area, pericardial thickness, and presence of respirophasic septal shift were all significantly different between patients with constriction and those without (P < .001 for all). IVC to aortic area ratio had the highest odds ratio for the prediction of constriction (1070, 95% confidence interval [8.0-143051], P = .005). ROC analysis illustrated that IVC to aortic area ratio discriminated between those with and without constriction with an area under the curve of 0.96 (95% confidence interval [0.91-1.00]). In patients referred for cardiac MRI assessment of suspected pericardial constriction, measurement of suprahepatic IVC cross-sectional area may be useful in confirming the diagnosis of constriction when used in combination with other imaging findings, including pericardial thickness and respirophasic septal shift. Copyright © 2015 Canadian Association of Radiologists. Published by Elsevier Inc. All rights reserved.

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

PubMed Central

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

2010-01-01

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

Effects of carvedilol on structural and functional outcomes and plasma biomarkers in the mouse transverse aortic constriction heart failure model

PubMed Central

Hampton, Caryn; Rosa, Raymond; Szeto, Daphne; Forrest, Gail; Campbell, Barry; Kennan, Richard; Wang, Shubing; Huang, Chin-Hu; Gichuru, Loise; Ping, Xiaoli; Shen, Xiaolan; Small, Kersten; Madwed, Jeffrey; Lynch, Joseph J

2017-01-01

Introduction: Despite the widespread use of the mouse transverse aortic constriction heart failure model, there are no reports on the characterization of the standard-of-care agent carvedilol in this model. Methods: Left ventricular pressure overload was produced in mice by transverse aortic constriction between the innominate and left common carotid arteries. Carvedilol was administered at multiple dose levels (3, 10 and 30 mg/kg/day per os; yielding end-study mean plasma concentrations of 0.002, 0.015 and 0.044 µM, respectively) in a therapeutic design protocol with treatment initiated after the manifestation of left ventricular remodeling at 3 weeks post transverse aortic constriction and continued for 10 weeks. Results: Carvedilol treatment in transverse aortic constriction mice significantly decreased heart rate and left ventricular dP/dt (max) at all dose levels consistent with β-adrenoceptor blockade. The middle dose of carvedilol significantly decreased left ventricular weight, whereas the higher dose decreased total heart, left and right ventricular weight and wet lung weight compared to untreated transverse aortic constriction mice. The higher dose of carvedilol significantly increased cardiac performance as measured by ejection fraction and fractional shortening and decreased left ventricular end systolic volume consistent with the beneficial effect on cardiac function. End-study plasma sST-2 and Gal-3 levels did not differ among sham, transverse aortic constriction control and transverse aortic constriction carvedilol groups. Plasma brain natriuretic peptide concentrations were elevated significantly in transverse aortic constriction control animals (~150%) compared to shams in association with changes in ejection fraction and heart weight and tended to decrease (~30%, p = 0.10–0.12) with the mid- and high-dose carvedilol treatment. Conclusion: A comparison of carvedilol hemodynamic and structural effects in the mouse transverse aortic

Effects of carvedilol on structural and functional outcomes and plasma biomarkers in the mouse transverse aortic constriction heart failure model.

PubMed

Hampton, Caryn; Rosa, Raymond; Szeto, Daphne; Forrest, Gail; Campbell, Barry; Kennan, Richard; Wang, Shubing; Huang, Chin-Hu; Gichuru, Loise; Ping, Xiaoli; Shen, Xiaolan; Small, Kersten; Madwed, Jeffrey; Lynch, Joseph J

2017-01-01

Despite the widespread use of the mouse transverse aortic constriction heart failure model, there are no reports on the characterization of the standard-of-care agent carvedilol in this model. Left ventricular pressure overload was produced in mice by transverse aortic constriction between the innominate and left common carotid arteries. Carvedilol was administered at multiple dose levels (3, 10 and 30 mg/kg/day per os ; yielding end-study mean plasma concentrations of 0.002, 0.015 and 0.044 µM, respectively) in a therapeutic design protocol with treatment initiated after the manifestation of left ventricular remodeling at 3 weeks post transverse aortic constriction and continued for 10 weeks. Carvedilol treatment in transverse aortic constriction mice significantly decreased heart rate and left ventricular dP/dt (max) at all dose levels consistent with β-adrenoceptor blockade. The middle dose of carvedilol significantly decreased left ventricular weight, whereas the higher dose decreased total heart, left and right ventricular weight and wet lung weight compared to untreated transverse aortic constriction mice. The higher dose of carvedilol significantly increased cardiac performance as measured by ejection fraction and fractional shortening and decreased left ventricular end systolic volume consistent with the beneficial effect on cardiac function. End-study plasma sST-2 and Gal-3 levels did not differ among sham, transverse aortic constriction control and transverse aortic constriction carvedilol groups. Plasma b rain natriuretic peptide concentrations were elevated significantly in transverse aortic constriction control animals (~150%) compared to shams in association with changes in ejection fraction and heart weight and tended to decrease (~30%, p = 0.10-0.12) with the mid- and high-dose carvedilol treatment. A comparison of carvedilol hemodynamic and structural effects in the mouse transverse aortic constriction model versus clinical use

A simplified method for correcting Tanzer's group II constricted ears: Construction of the superior crus as a strut with cartilage expansion grafting.

PubMed

Kim, Young Soo; Chung, Seum

2016-04-01

A constricted ear, also known as a cup ear or lop ear, is a deformity characterized by curling of the upper portion of the ear, including the helix, scapha, and antihelix. In Tanzer's classification, group II constricted ears have deformities involving the helix and the scapha. Although partial or total absence of the superior crus of the antihelix has been noted in group II constricted ears, most plastic surgeons have corrected group II constricted ears using the expansion technique and skin flaps, without formation of the superior crus. However, the expansion technique does not always yield satisfactory results in group II constricted ears. Between May 2011 and April 2014, the authors operated on 21 patients with group II constricted ears using the technique described in this study. The follow-up period ranged from 2 months to 2 years. In our procedure for correcting group II constricted ears, we focused on restoring the superior crus of the antihelix. As a strong superior crus acts as a strut in the upper third of the ear, it supports the helical rim and creates the scapha. Eventually, the newly formed superior crus enables the helical rim to expand in the upper third of the constricted ear. In this article, we present our method of correcting group II constricted ears, in which the superior crus is constructed as a strut and cartilage expansion grafts are used. Copyright © 2016 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 duringmore » 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.« less

[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. Copyright © 2014 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.

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

PubMed Central

Chang, Jennifer; Fedinec, Alexander L.; Kuntamallappanavar, Guruprasad; Leffler, Charles W.; Bukiya, Anna N.

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

Two-dimensional speckle tracking cardiac mechanics and constrictive pericarditis: systematic review.

PubMed

Madeira, Marta; Teixeira, Rogério; Costa, Marco; Gonçalves, Lino; Klein, Allan L

2016-10-01

Transthoracic echocardiography has a pivotal role in the diagnosis of constrictive pericarditis (CP). In addition to the classic M-mode, two-dimensional and Doppler indices, newer methodologies designed to evaluate myocardial mechanics, such as two-dimensional speckle tracking echocardiography (2DSTE), provide additional diagnostic and clinical information in the context of CP. Research has demonstrated that cardiac mechanics can improve echocardiographic diagnostic accuracy of CP and aid in differentiating between constrictive and restrictive ventricular physiology. 2DSTE can also be used to assess the success of pericardiectomy and its impact on atrial and ventricular mechanics. In the course of this review, we describe cardiac mechanics in patients with CP and summarize the influence of pericardiectomy on atrial and ventricular mechanics assessed using 2DSTE. © 2016, Wiley Periodicals, Inc.

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.

The cardiofaciocutaneous syndrome

PubMed Central

Roberts, A; Allanson, J; Jadico, S K; Kavamura, M I; Noonan, J; Opitz, J M; Young, T; Neri, G

2006-01-01

The cardiofaciocutaneous (CFC) syndrome is a condition of sporadic occurrence, with patients showing multiple congenital anomalies and mental retardation. It is characterised by failure to thrive, relative macrocephaly, a distinctive face with prominent forehead, bitemporal constriction, absence of eyebrows, hypertelorism, downward‐slanting palpebral fissures often with epicanthic folds, depressed nasal root and a bulbous tip of the nose. The cutaneous involvement consists of dry, hyperkeratotic, scaly skin, sparse and curly hair, and cavernous haemangiomata. Most patients have a congenital heart defect, most commonly pulmonic stenosis and hypertrophic cardiomyopathy. The developmental delay usually is moderate to severe. The syndrome is caused by gain‐of‐function mutations in four different genes BRAF, KRAS, mitogen‐activated protein/extracellular signal‐regulated kinase MEK1 and MEK2, all belonging to the same RAS–extracellular signal‐regulated kinase (ERK) pathway that regulates cell differentiation, proliferation and apoptosis. The CFC syndrome is a member of a family of syndromes that includes the Noonan and Costello syndromes, presenting with phenotypic similarities. Noonan syndrome is caused by mutations in the protein tyrosine phosphatase SHP‐2 gene (PTPN11), with a few people having a mutation in KRAS. Costello syndrome is caused by mutations in HRAS. The protein products of these genes also belong to the RAS–ERK pathway. Thus, the clinical overlap of these three conditions, which often poses a problem of differential diagnosis, is explained by their pathogenetic relatedness. PMID:16825433

Effects of the tripeptide substance P antagonist, FR113680, on airway constriction and airway edema induced by neurokinins in guinea-pigs.

PubMed

Murai, M; Morimoto, H; Maeda, Y; Fujii, T

1992-06-24

FR113680 is a newly developed tripeptide substance P (SP) receptor antagonist. The effects of FR113680 on airway constriction and airway edema induced by neurokinins were investigated in guinea-pigs. In in vitro experiments, FR113680 inhibited the contraction of isolated guinea-pig trachea induced by SP and neurokinin A (NKA) in a dose-dependent manner with IC50 values of 2.3 x 10(-6) and 1.5 x 10(-5) M, respectively. The tracheal contraction induced by histamine and acetylcholine was not affected by FR113680. FR113680 (5 x 10(-5) M) also significantly inhibited the atropine-resistant contraction of isolated guinea-pig bronchi induced by electrical field stimulation. In in vivo experiments, FR113680 given i.v. inhibited SP-induced airway constriction in guinea-pigs at doses of 1 and 10 mg kg-1. However, FR113680 only inhibited NKA- and capsaicin-induced airway constriction by 40-50% even at a dose of 10 mg kg-1. FR113680 also inhibited SP-induced airway edema in guinea-pigs with the same potency as it inhibited SP-induced airway constriction. Histamine-induced airway constriction and airway edema were not affected at a dose of 10 mg kg-1. These results suggest that FR113680 preferentially inhibits responses induced by NK1 receptor activation (SP-induced airway constriction and airway edema), but is less effective on a NK2 receptor-induced response (airway constriction by NKA and neurogenic stimulation).

The hypermorph FtsA* protein has an in vivo role in relieving the Escherichia coli proto-ring block caused by excess ZapC+

PubMed Central

Ortiz, Cristina; Casanova, Mercedes; Palacios, Pilar

2017-01-01

Assembly of the proto-ring, formed by the essential FtsZ, FtsA and ZipA proteins, and its progression into a divisome, are essential events for Escherichia coli division. ZapC is a cytoplasmic protein that belongs to a group of non-essential components that assist FtsZ during proto-ring assembly. Any overproduction of these proteins leads to faulty FtsZ-rings, resulting in a cell division block. We show that ZapC overproduction can be counteracted by an excess of the ZipA-independent hypermorph FtsA* mutant, but not by similar amounts of wild type FtsA+. An excess of FtsA+ allowed regular spacing of the ZapC-blocked FtsZ-rings, but failed to promote recruitment of the late-assembling proteins FtsQ, FtsK and FtsN and therefore, to activate constriction. In contrast, overproduction of FtsA*, besides allowing correct FtsZ-ring localization at midcell, restored the ability of FtsQ, FtsK and FtsN to be incorporated into active divisomes. PMID:28877250

Comparison of adenosine, isoflurane, and desflurane on myocardial tissue oxygen pressure during coronary artery constriction in dogs.

PubMed

Hoffman, William E; Albrecht, Ronald F; Jonjev, Zivojin S

2003-08-01

To compare adenosine-, isoflurane-, or desflurane-induced hypotension with and without left anterior descending (LAD) coronary artery constriction for the effects on myocardial tissue oxygen pressure (PmO(2)) in dogs. Prospective, randomized, nonblinded. University teaching hospital. Male nonpurpose-bred dogs (n = 18). Dogs were anesthetized with 1.5% isoflurane (n = 12) or 8% desflurane (n = 6). A flow probe and balloon occluder were placed on the LAD artery. A probe that measured myocardial oxygen pressure was inserted into the middle myocardium in the LAD region. Myocardial oxygen consumption (MVO(2)) was calculated as LAD flow x arterial minus coronary sinus oxygen content. Measures were made during hypotension produced by adenosine infusion, 2.8% isoflurane, or 14% desflurane with and without LAD constriction to decrease blood flow 30%. Without LAD artery constriction, adenosine infusion increased LAD flow 90% and MVO(2) 70%, 2.8% isoflurane produced no change in MVO(2), and 14% desflurane decreased MVO(2) 25%, but no treatment changed PmO(2). LAD artery constriction decreased PmO(2) 50% by itself. Adenosine infusion during LAD constriction decreased tissue oxygen pressure an additional 60%, 2.8% isoflurane produced no change, and 14% desflurane increased PmO(2) 100%. There was an inverse relationship between the effect of adenosine, 2.8% isoflurane, and 14% desflurane on MVO(2) and PmO(2) during ischemia. This is consistent with reports that increasing oxygen demand worsens myocardial ischemia.

Apical constriction is driven by a pulsatile apical myosin network in delaminating Drosophila neuroblasts.

PubMed

An, Yanru; Xue, Guosheng; Shaobo, Yang; Mingxi, Deng; Zhou, Xiaowei; Yu, Weichuan; Ishibashi, Toyotaka; Zhang, Lei; Yan, Yan

2017-06-15

Cell delamination is a conserved morphogenetic process important for the generation of cell diversity and maintenance of tissue homeostasis. Here, we used Drosophila embryonic neuroblasts as a model to study the apical constriction process during cell delamination. We observe dynamic myosin signals both around the cell adherens junctions and underneath the cell apical surface in the neuroectoderm. On the cell apical cortex, the nonjunctional myosin forms flows and pulses, which are termed medial myosin pulses. Quantitative differences in medial myosin pulse intensity and frequency are crucial to distinguish delaminating neuroblasts from their neighbors. Inhibition of medial myosin pulses blocks delamination. The fate of a neuroblast is set apart from that of its neighbors by Notch signaling-mediated lateral inhibition. When we inhibit Notch signaling activity in the embryo, we observe that small clusters of cells undergo apical constriction and display an abnormal apical myosin pattern. Together, these results demonstrate that a contractile actomyosin network across the apical cell surface is organized to drive apical constriction in delaminating neuroblasts. © 2017. Published by The Company of Biologists Ltd.

Comparison of fundus autofluorescence with photopic and scotopic fine matrix mapping in patients with retinitis pigmentosa: 4- to 8-year follow-up.

PubMed

Robson, Anthony G; Lenassi, Eva; Saihan, Zubin; Luong, Vy A; Fitzke, Fred W; Holder, Graham E; Webster, Andrew R

2012-09-14

To assess the significance and evolution of parafoveal rings of high-density fundus autofluorescence (AF) in 12 patients with retinitis pigmentosa (RP). Twelve patients with autosomal recessive RP or Usher syndrome type 2 were ascertained who had a parafoveal ring of high-density AF and a visual acuity of 20/30 or better at baseline. Photopic and scotopic fine matrix mapping (FMM) were performed to test sensitivity across the macula. AF imaging and FMM were repeated after 4 to 8 years and optical coherence tomography (OCT) performed. The size of the AF ring reduced over time and disappeared in one subject. Photopic thresholds were normal over the fovea; thresholds were elevated by 0.6 log units over the ring and by 1.2 log units external to the ring at baseline and differed by less than 0.1 log unit at follow-up. Mild photopic losses close to the internal edge of the ring were detected at baseline or follow-up in all. Mean scotopic thresholds over parafoveal areas within the ring were markedly elevated in 8 of 10 at baseline and were severely elevated in 9 of 11 at follow-up. The eccentricity of the inner edge of the AF ring corresponded closely with the lateral extent of the inner segment ellipsoid band in the OCT image. Ring constriction was largely coincident with progressive centripetal photopic threshold elevation led by worsening of rod photoreceptor function. The rate of constriction differed across patients, and a ring may reach a critical minimum before disappearing, at which stage central visual loss occurs. The structural and functional changes associated with rings of increased autofluorescence confirm that they provide an objective index of macular involvement and may aid the management of RP patients and the monitoring of future treatment efficacy.

Use of a Novel Two Color PALM Method to Examine Structural Properties of Drp1 Helical Rings during Mammalian Mitochondrial Fission In Situ

NASA Astrophysics Data System (ADS)

Rosenbloom, Alyssa Blair

membranes with large populations of membrane bound rsKame and PAmCherry1 in HeLa and EpH4 cells. We were able to observe and clearly differentiate the two mitochondrial membrane structures and their various morphologies in situ. With the functional two-color PALM method, we returned to our original investigation of the Drp1 fission ring in situ. In fixed HeLa cells, we continued to label the outer membrane with PAmCherry1 and fused rsKame to the N-terminus of Drp1, separated by a linker. The resultant PALM images allowed for the observation of two previously observed and one hitherto unseen distinct Drp1 morphologies: Constrict, Terminal, and Split. The Constrict morphology was defined as the Drp1 structures that clearly encircle the mitochondrial tubule at various stages of membrane constriction. The Terminal morphology was defined as the Drp1 structures found at the termini of mitochondria, presumably post membrane scission. The Split morphology is a novel morphology and was defined as two Drp1 foci flanking the mitochondrial tubule but not completely encircling it. Quantification of the diameter and length of the Drp1 helical ring structures showed that the mean length of the Drp1 helical rings was consistent between all three morphologies, though a slight decrease was observed for the Terminal morphology, likely due to degradation. We observed a decrease of approximately 40 nm between the Constrict and Terminal mean diameters, consistent with a dynamic change in the Drp1 ring size due to membrane constriction towards membrane scission during mitochondrial fission. The Split morphology had a wide distribution of diameters and warrants further study. (Abstract shortened by UMI.)

Cylindrical cellular geometry ensures fidelity of division site placement in fission yeast.

PubMed

Mishra, Mithilesh; Huang, Yinyi; Srivastava, Pragya; Srinivasan, Ramanujam; Sevugan, Mayalagu; Shlomovitz, Roie; Gov, Nir; Rao, Madan; Balasubramanian, Mohan

2012-08-15

Successful cytokinesis requires proper assembly of the contractile actomyosin ring, its stable positioning on the cell surface and proper constriction. Over the years, many of the key molecular components and regulators of the assembly and positioning of the actomyosin ring have been elucidated. Here we show that cell geometry and mechanics play a crucial role in the stable positioning and uniform constriction of the contractile ring. Contractile rings that assemble in locally spherical regions of cells are unstable and slip towards the poles. By contrast, actomyosin rings that assemble on locally cylindrical portions of the cell under the same conditions do not slip, but uniformly constrict the cell surface. The stability of the rings and the dynamics of ring slippage can be described by a simple mechanical model. Using fluorescence imaging, we verify some of the quantitative predictions of the model. Our study reveals an intimate interplay between geometry and actomyosin dynamics, which are likely to apply in a variety of cellular contexts.

Bone-borne palatal distraction to correct the constricted cleft maxilla.

PubMed

Vyas, Raj M; Jarrahy, Reza; Sisodia, Manisha; Jourabchi, Natanel; Wasson, Kristy L; Bradley, James P

2009-05-01

Transverse maxillary hypoplasia, with or without cleft deformity, is typically treated with orthodontic expansion. However, the management of those patients who present later in life with severe uncorrected deformities or who have failed prior orthodontic care remains controversial. Tooth-borne palatal expanders have limitations in this subset of patients with scarred, constricted cleft palate. In this study, we assess the efficacy and safety of using a bone-borne palatal distraction device as an alternative treatment for this difficult subset of patients. Older children with a constricted maxilla who previously had unilateral or bilateral cleft lip and palate repairs and failed orthodontic expansion were included in the study (n = 15). Patients underwent Le Fort I corticotomy with placement of the bone-borne distraction device, expansion at a rate of 0.5 mm/d, and subsequent alveolar bone grafting. Preoperative and follow-up maxillary impressions were compared with assessed improvements in intermolar distance, intercanine distance, alveolar cleft width, and total palatal area. In addition, a small group of noncleft patients with constricted maxillas was treated with bone-borne palatal distraction without a corticotomy (n = 4). The mean amount of distraction in all patients was 14.1 mm, with a follow-up period of 19 months (range, 8-30 months). The average increase in intermolar distance was 8.4 mm, intercanine distance increased by an average of 9.5 mm, and palate surface areas were increased by a mean of 28.9 mm2. Relapse was between 4% and 7%, and all patients underwent subsequent alveolar bone grafting. In addition, the noncleft patients successfully underwent bone-borne palatal distraction without a corticotomy, with a 4% to 5% relapse. Rapid palatal expansion using a bone-borne distraction device in cleft patients with transverse maxillary hypoplasia who have failed nonsurgical orthodontic expansion provides adequate expansion necessary for alveolar bone

Cell division requires a direct link between microtubule-bound RacGAP and Anillin in the contractile ring.

PubMed

Gregory, Stephen L; Ebrahimi, Saman; Milverton, Joanne; Jones, Whitney M; Bejsovec, Amy; Saint, Robert

2008-01-08

The mitotic microtubule array plays two primary roles in cell division. It acts as a scaffold for the congression and separation of chromosomes, and it specifies and maintains the contractile-ring position. The current model for initiation of Drosophila and mammalian cytokinesis [1-5] postulates that equatorial localization of a RhoGEF (Pbl/Ect2) by a microtubule-associated motor protein complex creates a band of activated RhoA [6], which subsequently recruits contractile-ring components such as actin, myosin, and Anillin [1-3]. Equatorial microtubules are essential for continued constriction, but how they interact with the contractile apparatus is unknown. Here, we report the first direct molecular link between the microtubule spindle and the actomyosin contractile ring. We find that the spindle-associated component, RacGAP50C, which specifies the site of cleavage [1-5], interacts directly with Anillin, an actin and myosin binding protein found in the contractile ring [7-10]. Both proteins depend on this interaction for their localization. In the absence of Anillin, the spindle-associated RacGAP loses its association with the equatorial cortex, and cytokinesis fails. These results account for the long-observed dependence of cytokinesis on the continual presence of microtubules at the cortex.

Enamel Pit Defects and Taurodontism in a Patient with Ring Chromosome 14 and 47,XXX.

PubMed

Townsend, Janice A; Lacour, Letitia; Scheuerle, Angela E

2017-01-15

The purpose of this paper is to describe the clinical findings and management of a case involving a patient with co-occurring ring chromosome 14 syndrome and 47,XXX presenting with enamel pit defects and taurodontism. Ring chromosome 14 syndrome is an unusual condition with uncontrolled seizure disorder as its most significant finding; 47,XXX (trisomy X; triple X) is a more common condition and has characteristic physical and behavioral findings. Neither condition has been associated with enamel pit defects.

Chemical substitutions in the selectivity filter of potassium channels do not rule out constricted-like conformations for C-type inactivation

PubMed Central

Li, Jing; Boulanger, Eliot; Rui, Huan; Perozo, Eduardo; Roux, Benoît

2017-01-01

In many K+ channels, prolonged activating stimuli lead to a time-dependent reduction in ion conduction, a phenomenon known as C-type inactivation. X-ray structures of the KcsA channel suggest that this inactivated state corresponds to a “constricted” conformation of the selectivity filter. However, the functional significance of the constricted conformation has become a matter of debate. Functional and structural studies based on chemically modified semisynthetic KcsA channels along the selectivity filter led to the conclusion that the constricted conformation does not correspond to the C-type inactivated state. The main results supporting this view include the observation that C-type inactivation is not suppressed by a substitution of D-alanine at Gly77, even though this modification is believed to lock the selectivity filter into its conductive conformation, whereas it is suppressed following amide-to-ester backbone substitutions at Gly77 and Tyr78, even though these structure-conserving modifications are not believed to prevent the selectivity filter from adopting the constricted conformation. However, several untested assumptions about the structural and functional impact of these chemical modifications underlie these arguments. To make progress, molecular dynamics simulations based on atomic models of the KcsA channel were performed. The computational results support the notion that the constricted conformation of the selectivity filter corresponds to the functional C-type inactivated state of the KcsA. Importantly, MD simulations reveal that the semisynthetic KcsAD-ala77 channel can adopt an asymmetrical constricted-like nonconductive conformation and that the amide-to-ester backbone substitutions at Gly77 and Tyr78 perturb the hydrogen bonding involving the buried water molecules stabilizing the constricted conformation. PMID:28973956

Myogenic constriction is increased in mesenteric resistance arteries from rats with chronic heart failure: instantaneous counteraction by acute AT1 receptor blockade

PubMed Central

Gschwend, S; Henning, R H; Pinto, Y M; de Zeeuw, D; van Gilst, W H; Buikema, H

2003-01-01

Increased vascular resistance in chronic heart failure (CHF) has been attributed to stimulated neurohumoral systems. However, local mechanisms may also importantly contribute to set arterial tone. Our aim, therefore, was to test whether pressure-induced myogenic constriction of resistance arteries in vitro – devoid of acute effects of circulating factors – is increased in CHF and to explore underlying mechanisms. At 12 weeks after coronary ligation-induced myocardial infarction or SHAM-operations in rats, we studied isolated mesenteric arteries for myogenic constriction, determined as the active constriction (% of passive diameter) in response to stepwise increase in intraluminal pressure (20 – 160 mmHg), in the absence and presence of inhibitors of potentially involved modulators of myogenic constriction. We found that myogenic constriction in mesenteric arteries from CHF rats was markedly increased compared to SHAM over the whole pressure range, the difference being most pronounced at 60 mmHg (24±2 versus 4±3%, respectively, P<0.001). Both removal of the endothelium as well as inhibition of NO production (L-NG-monomethylarginine, 100 μM) significantly increased myogenic constriction (+16 and +25%, respectively), the increase being similar in CHF- and SHAM-arteries (P=NS). Neither endothelin type A (ETA)-receptor blockade (BQ123, 1 μM) nor inhibition of perivascular (sympathetic) nerve conduction (tetrodotoxin, 100 nM) affected the myogenic response in either group. Interestingly, increased myogenic constriction in CHF was fully reversed after angiotensin II type I (AT1)-receptor blockade (candesartan, 100 nM; losartan, 10 μM), which was without effect in SHAM. In contrast, neither angiotensin-converting enzyme (ACE) inhibition (lisinopril, 1 μM; captopril, 10 μM) or AT2-receptor blockade (PD123319, 1 μM), nor inhibition of superoxide production (superoxide dismutase, 50 U ml−1), TXA2-receptor blockade (SQ29,548, 1 μM) or inhibition of

Evaluation of constricted affect in chronic pain: an attempt using the Toronto Alexythymia Scale.

PubMed

Millard, R W; Kinsler, B L

1992-09-01

The Toronto Alexythymia Scale (TAS) was applied as a potential measure of constricted affect among a sample of patients with chronic, non-malignant pain (n = 195). As previously demonstrated with non-clinical samples, the scale was found to possess moderate reliability with two principal internal factors. These factors seemed to reflect social introversion and a lack of proneness to fantasy. There was a moderate, negative association between them. The domain sampled by the TAS was apparently heterogeneous, with total scores showing no relationship to reported disability or pain intensity and a low relationship to reported distress. These results suggest potential limitations of the TAS and the alexythymia construct as means for evaluating constricted affect that accompanies chronic pain.

A Marfan syndrome-like phenotype caused by a neocentromeric supernumerary ring chromosome 15.

PubMed

Quinonez, Shane C; Gelehrter, Thomas D; Uhlmann, Wendy R

2017-01-01

Small supernumerary marker chromosomes (sSMC) are abnormal chromosomes that cannot be characterized by standard banding cytogenetic techniques. A minority of sSMC contain a neocentromere, which is an ectopic centromere lacking the characteristic alpha-satellite DNA. The phenotypic manifestations of sSMC and neocentromeric sSMC are variable and range from severe intellectual disability and multiple congenital anomalies to a normal phenotype. Here we report a patient with a diagnosis of Marfan syndrome and infertility found to have an abnormal karyotype consisting of a chromosome 15 deletion and a ring-type sSMC likely stabilized by a neocentromere derived via a mechanism initially described by Barbara McClintock in 1938. Analysis of the sSMC identified that it contained the deleted chromosome 15 material and also one copy of FBN1, the gene responsible for Marfan syndrome. We propose that the patient's diagnosis arose from disruption of the FBN1 allele on the sSMC. To date, a total of 29 patients have been reported with an sSMC derived from a chromosomal deletion. We review these cases with a specific focus on the resultant phenotypes and note significant difference between this class of sSMC and other types of sSMC. Through this review we also identified a patient with a clinical diagnosis of neurofibromatosis type 1 who lacked a family history of the condition but was found to have a chromosome 17-derived sSMC that likely contained NF1 and caused the patient's disorder. We also review the genetic counseling implications and recommendations for a patient or family harboring an sSMC. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

A microperfusion study of sucrose movement across the rat proximal tubule during renal vein constriction

PubMed Central

Bank, Norman; Yarger, William E.; Aynedjian, Hagop S.

1971-01-01

Constriction of the renal vein has been shown to inhibit net sodium and water reabsorption by the rat proximal tubule. The mechanism is unknown but might be the result of inhibition of the active sodium pump induced by changes in the interstitial fluid compartment of the kidney, or to enhanced passive backflux of sodium and water into the cell or directly into the tubular lumen. Since passive movement of solutes across epithelial membranes is determined in part by the permeability characteristics of the epithelium, an increase in the permeability of the proximal tubule during venous constriction would suggest that enhanced passive flux is involved in the inhibition of reabsorption. In the present experiments, isolated segments of rat proximal convoluted tubules were microperfused in vivo with saline while the animals were receiving 14C-labeled sucrose intravenously. In normal control animals, no sucrose was detected in the majority of the collected tubular perfusates. In rats with renal vein constriction (RVC), however, sucrose consistently appeared in the tubular perfusates. The rate of inflow of sucrose correlated with the length of the perfused segment, estimated by fractional water reabsorption. In another group of animals with renal vein constriction, inulin-14C was given intravenously and the proximal tubules similarly microperfused. Inulin did not appear in the majority of collected perfusates in these animals. These observations indicate that a physiological alteration in the permeability of the proximal tubule occurs during RVC. Such an increase in permeability is consistent with the view that enhanced passive extracellular back-flux plays a role in the reduction of net sodium and water reabsorption in this experimental condition. PMID:5540167

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.

Allergic inflammation induces a persistent mechanistic switch in thromboxane-mediated airway constriction in the mouse

PubMed Central

Cyphert, Jaime M.; Allen, Irving C.; Church, Rachel J.; Latour, Anne M.; Snouwaert, John N.; Coffman, Thomas M.

2012-01-01

Actions of thromboxane (TXA2) to alter airway resistance were first identified over 25 years ago. However, the mechanism underlying this physiological response has remained largely undefined. Here we address this question using a novel panel of mice in which expression of the thromboxane receptor (TP) has been genetically manipulated. We show that the response of the airways to TXA2 is complex: it depends on expression of other G protein-coupled receptors but also on the physiological context of the signal. In the healthy airway, TXA2-mediated airway constriction depends on expression of TP receptors by smooth muscle cells. In contrast, in the inflamed lung, the direct actions of TXA2 on smooth muscle cell TP receptors no longer contribute to bronchoconstriction. Instead, in allergic lung disease, TXA2-mediated airway constriction depends on neuronal TP receptors. Furthermore, this mechanistic switch persists long after resolution of pulmonary inflammation. Our findings demonstrate the powerful ability of lung inflammation to modify pathways leading to airway constriction, resulting in persistent changes in mechanisms of airway reactivity to key bronchoconstrictors. Such alterations are likely to shape the pathogenesis of asthmatic lung disease. PMID:21984570

DC biased low-frequency insulating constriction dielectrophoresis for protein biomolecules concentration.

PubMed

Zhang, Peng; Liu, Yuxin

2017-09-01

Sample enrichment or molecules concentration is considered an essential step in sample processing of miniaturized devices aimed at biosensing and bioanalysis. Among all the means involved to achieve this aim, dielectrophoresis (DEP) is increasingly employed in molecules manipulation and concentration because it is non-destructive and high efficiency. This paper presents a methodology to achieve protein concentration utilizing the combination effects of electrokinetics and low frequency insulating dielectrophoresis (iDEP) generated within a microfluidic device, in which a submicron constricted channel was fabricated using DNA molecular combing and replica molding. This fabrication technique avoids using e-beam lithography or other complicated nanochannel fabrication methods, and provides an easy and low cost approach with the flexibility of controlling channel dimensions to create highly constricted channels embedded in a microfluidic device. With theoretical analysis and experiments, we demonstrated that fluorescein isothiocyanate conjugated bovine serum albumin (FITC-BSA) protein molecules can be significantly concentrated to form an arc-shaped band near the constricted channel under the effects of a negative dielectrophoretic force and DC electrokinetic forces within a short period of time. It was also observed that the amplitudes of the applied DC and AC electric fields, the AC frequencies as well as the suspending medium conductivities had strong effects on the concentration responses of the FITC-BSA molecules, including the concentrated area and position, intensities of the focused molecules, and concentration speed. Our method provides a simple and flexible approach for quickly concentrating protein molecules by controlling the applied electric field parameters. The iDEP device reported in this paper can be used as a stand-alone sensor or worked as a pre-concentration module integrated with biosensors for protein biomarker detection. Furthermore, low

Reconstruction of Moderately Constricted Ears by Combining V-Y Advancement of Helical Root, Conchal Cartilage Graft, and Mastoid Hitch.

PubMed

Elshahat, Ahmed; Lashin, Riham

2016-01-01

Despite the multitude of corrective procedures described in the literature, adequate surgical correction of the congenital constricted ear remains a challenge. The maintenance of the shape and size of the reconstructed upper neohelix poses a particular problem. In the present study, a total of 12 cases of reconstruction were undertaken. All of them were moderate (type IIA Tanzer classification) deformities. A combined procedure was adopted using a V-Y advancement of the helical root, cartilage scoring, and cartilage grafting from the contralateral concha to reconstruct the upper helix. A mastoid hitch was used as an adjunct to these procedures to maintain helical elevation and prevent recurrence. Mean follow-up period was 6 months. RESULTS were excellent (n = 7), good (n = 4), and fair (n = 1). Paired t test showed a significant increase in the height of the constricted ear postoperatively (P < .001) and a nonsignificant difference between the height of the constricted and contralateral ears postoperatively (P > .05). Apart from dislodgment of the mastoid hitch suture in 1 patient, no complications were recorded. This combined technique is useful in correcting moderately constricted ear deformities.

Local small airway epithelial injury induces global smooth muscle contraction and airway constriction.

PubMed

Zhou, Jian; Alvarez-Elizondo, Martha B; Botvinick, Elliot; George, Steven C

2012-02-01

Small airway epithelial cells form a continuous sheet lining the conducting airways, which serves many functions including a physical barrier to protect the underlying tissue. In asthma, injury to epithelial cells can occur during bronchoconstriction, which may exacerbate airway hyperreactivity. To investigate the role of epithelial cell rupture in airway constriction, laser ablation was used to precisely rupture individual airway epithelial cells of small airways (<300-μm diameter) in rat lung slices (∼250-μm thick). Laser ablation of single epithelial cells using a femtosecond laser reproducibly induced airway contraction to ∼70% of the original cross-sectional area within several seconds, and the contraction lasted for up to 40 s. The airway constriction could be mimicked by mechanical rupture of a single epithelial cell using a sharp glass micropipette but not with a blunt glass pipette. These results suggest that soluble mediators released from the wounded epithelial cell induce global airway contraction. To confirm this hypothesis, the lysate of primary human small airway epithelial cells stimulated a similar airway contraction. Laser ablation of single epithelial cells triggered a single instantaneous Ca(2+) wave in the epithelium, and multiple Ca(2+) waves in smooth muscle cells, which were delayed by several seconds. Removal of extracellular Ca(2+) or decreasing intracellular Ca(2+) both blocked laser-induced airway contraction. We conclude that local epithelial cell rupture induces rapid and global airway constriction through release of soluble mediators and subsequent Ca(2+)-dependent smooth muscle shortening.

Mechanical roles of apical constriction, cell elongation, and cell migration during neural tube formation in Xenopus.

PubMed

Inoue, Yasuhiro; Suzuki, Makoto; Watanabe, Tadashi; Yasue, Naoko; Tateo, Itsuki; Adachi, Taiji; Ueno, Naoto

2016-12-01

Neural tube closure is an important and necessary process during the development of the central nervous system. The formation of the neural tube structure from a flat sheet of neural epithelium requires several cell morphogenetic events and tissue dynamics to account for the mechanics of tissue deformation. Cell elongation changes cuboidal cells into columnar cells, and apical constriction then causes them to adopt apically narrow, wedge-like shapes. In addition, the neural plate in Xenopus is stratified, and the non-neural cells in the deep layer (deep cells) pull the overlying superficial cells, eventually bringing the two layers of cells to the midline. Thus, neural tube closure appears to be a complex event in which these three physical events are considered to play key mechanical roles. To test whether these three physical events are mechanically sufficient to drive neural tube formation, we employed a three-dimensional vertex model and used it to simulate the process of neural tube closure. The results suggest that apical constriction cued the bending of the neural plate by pursing the circumference of the apical surface of the neural cells. Neural cell elongation in concert with apical constriction further narrowed the apical surface of the cells and drove the rapid folding of the neural plate, but was insufficient for complete neural tube closure. Migration of the deep cells provided the additional tissue deformation necessary for closure. To validate the model, apical constriction and cell elongation were inhibited in Xenopus laevis embryos. The resulting cell and tissue shapes resembled the corresponding simulation results.

Chromothripsis and ring chromosome 22: a paradigm of genomic complexity in the Phelan-McDermid syndrome (22q13 deletion syndrome)

PubMed Central

Kurtas, Nehir; Arrigoni, Filippo; Errichiello, Edoardo; Zucca, Claudio; Maghini, Cristina; D’Angelo, Maria Grazia; Beri, Silvana; Giorda, Roberto; Bertuzzo, Sara; Delledonne, Massimo; Xumerle, Luciano; Rossato, Marzia; Zuffardi, Orsetta; Bonaglia, Maria Clara

2018-01-01

Introduction Phelan-McDermid syndrome (PMS) is caused by SHANK3 haploinsufficiency. Its wide phenotypic variation is attributed partly to the type and size of 22q13 genomic lesion (deletion, unbalanced translocation, ring chromosome), partly to additional undefined factors. We investigated a child with severe global neurodevelopmental delay (NDD) compatible with her distal 22q13 deletion, complicated by bilateral perisylvian polymicrogyria (BPP) and urticarial rashes, unreported in PMS. Methods Following the cytogenetic and array-comparative genomic hybridization (CGH) detection of a r(22) with SHANK3 deletion and two upstream duplications, whole-genome sequencing (WGS) in blood and whole-exome sequencing (WES) in blood and saliva were performed to highlight potential chromothripsis/chromoanagenesis events and any possible BPP-associated variants, even in low-level mosaicism. Results WGS confirmed the deletion and highlighted inversion and displaced order of eight fragments, three of them duplicated. The microhomology-mediated insertion of partial Alu-elements at one breakpoint junction disrupted the topological associating domain joining NFAM1 to the transcriptional coregulator TCF20. WES failed to detect BPP-associated variants. Conclusions Although we were unable to highlight the molecular basis of BPP, our data suggest that SHANK3 haploinsufficiency and TCF20 misregulation, both associated with intellectual disability, contributed to the patient’s NDD, while NFAM1 interruption likely caused her skin rashes, as previously reported. We provide the first example of chromoanasynthesis in a constitutional ring chromosome and reinforce the growing evidence that chromosomal rearrangements may be more complex than estimated by conventional diagnostic approaches and affect the phenotype by global alteration of the topological chromatin organisation rather than simply by deletion or duplication of dosage-sensitive genes. PMID:29378768

The prevalence of phantom vibration/ringing syndromes and their related factors in Iranian' students of medical sciences.

PubMed

Mohammadbeigi, Abolfazl; Mohammadsalehi, Narges; Moshiri, Esmail; Anbari, Zohreh; Ahmadi, Ali; Ansari, Hossein

2017-06-01

Mobile phone abuse can cause pathologic stress that may lead to addictive behavior such as Phantom Vibration Syndrome (PVS) and Phantom Ringing Syndrome (PRS). The current study aimed to determine the PVS and PRS due to mobile phone use in students of Qom University of medical Sciences in Iran. Cross-sectional study. The participants were 380 students selected by proportional stratified random sampling method in each stratum. Data were collected by a self-administered questionnaire and analyzed by descriptive and analytic statistical methods including t-test, chi square and analysis of variance. The prevalence of PVS and PRS due to mobile phones in students of medical sciences was estimated to be 54.3% and 49.3%, respectively. PVS was higher in female students than in males while the PRS was higher in male students. There was a significant relationship between PVS and using social networks such as Viber, WhatsApp, and Line. In addition, a significant association was observed between PVS and friend-finding, chatting and entertainment. Studies should be done in the future to assess the long-term complication of overusing mobile phones. In the current study, the prevalence of PVS and PRS in half of students is considerable. Copyright © 2017 Elsevier B.V. All rights reserved.

Double second toe transfer in congenital hand anomalies.

PubMed

Van Holder, C; Giele, H; Gilbert, A

1999-08-01

A series of 14 patients with congenital hand anomalies who received staged double second toe transfers to the same hand for restoration of function or form were reviewed retrospectively. There were three children with constriction ring syndrome, two with symbrachydactyly and nine with transverse absence (failure of formation). There were different indications, technical difficulties and results with the various anomalies. All transferred toes were mobile and sensate, and were reported to be of benefit in both function and appearance. However, secondary surgical procedures were required in all patients.

Anomalous right coronary artery arising from the pulmonary artery and constrictive pericarditis: an unusual association

PubMed Central

Silvestre, Odilson Marcos; Adam, Eduardo Leal; de Melo, Dirceu Thiago Pessoa; Dias, Ricardo Ribeiro; Ramires, Felix J. A.; Mady, Charles

2013-01-01

ABSTRACT The association of anomalous right coronary artery originating from the pulmonary artery and constrictive pericarditis has never been showed in the literature. We present the first case of this unusual association in a patient with right heart failure. After diagnosis, the patient was referred to surgery and underwent phrenic-to-phrenic pericardiectomy; graft implant of right internal thoracic artery to right coronary artery; and ligation of the anomalous origin of the right coronary artery from the pulmonary artery. Such procedures solved the potential risk of sudden death related to anomalous right coronary artery originating from the pulmonary artery and alleviated the symptoms of heart failure caused by constrictive pericarditis. PMID:24136766

Foam flows through a local constriction

NASA Astrophysics Data System (ADS)

Chevalier, T.; Koivisto, J.; Shmakova, N.; Alava, M. J.; Puisto, A.; Raufaste, C.; Santucci, S.

2017-11-01

We present an experimental study of the flow of a liquid foam, composed of a monolayer of millimetric bubbles, forced to invade an inhomogeneous medium at a constant flow rate. To model the simplest heterogeneous fracture medium, we use a Hele-Shaw cell consisting of two glass plates separated by a millimetric gap, with a local constriction. This single defect localized in the middle of the cell reduces locally its gap thickness, and thus its local permeability. We investigate here the influence of the geometrical property of the defect, specifically its height, on the average steady-state flow of the foam. In the frame of the flowing foam, we can observe a clear recirculation around the obstacle, characterized by a quadrupolar velocity field with a negative wake downstream the obstacle, which intensity evolves systematically with the obstacle height.

[Origin and morphological features of small supernumerary marker chromosomes in Turner syndrome].

PubMed

Liu, Nan; Tong, Tong; Chen, Yue; Chen, Yanling; Cai, Chunquan

2018-02-10

OBJECTIVE To explore the origin and morphological features of small supernumerary marker chromosomes (sSMCs) in Turner syndrome. METHODS For 5 cases of Turner syndrome with a sSMC identified by conventional G-banding, dual-color fluorescence in situ hybridization (FISH) was applied to explore their origin and morphological features. RESULTS Among the 5 cases, 3 have derived from the X chromosome, which included 2 ring chromosomes and 1 centric minute. For the 2 sSMCs derived from the Y chromosome, 1 was ring or isodicentric chromosome, while the other was an isodicentric chromosome. CONCLUSION The sSMCs found in Turner syndrome have almost all derived from sex chromosomes. The majority of sSMCs derived from the X chromosome will form ring chromosomes, while a minority will form centric minute. While most sSMC derived from Y chromosome may exist as isodicentric chromosomes, and a small number may exist as rings. For Turner syndrome patients with sSMCs, dual-color FISH may be used to delineate their origins to facilitate genetic counseling and selection of clinical regime.

Hemizygosity at the IGF1R locus correlates with growth delay in the ring chromosome 15 syndrome

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peoples, R.; Francke, U.

1994-09-01

The ring 15 syndrome is characterized by intrauterine growth retardation, mental retardation, postnatal growth failure, triangular facies, 5th finger clinodactyly, leg-length discrepancy, cafe-au-lait spots and cryptorchidism. The degree of short stature varies from mild to severe and is associated with normal growth hormone and IGF-1 levels, but a wide range of bone age delay. These children retain de novo rings with breakpoints in the short arm at 15p12-11 and in the long arm at 15q26, the region to which the insulin-like growth factor type 1 receptor (IGFIR) has been mapped. We investigated if the degree of growth failure correlates withmore » disruption loss of the IGF1R gene. Ring breakpoints for all patients were determined by typing of RFLP and microsatellite markers from distal 15q for patients and their parents. The order of the loci studied is cen-IVD-FES-D15S130-E15S107-D15S87-D15S86-D15S3. All breakpoints mapped distal to D15S100. Presence or absence of the IGF1R gene on the ring chromsomes of five patients was ascertained by in situ hybridization and gene dosage blots using probes for the more proximally located genes IVD and c-Fes as controls. Heterozygosity for one patient was also confirmed by typing of a polymorphism in the 3{prime} UTR of IGF1R. Two patients who retained the IGF1R were hemizygous at D15S87 while two lacking the IGF1R retained D15S107 indicating that the IGF1R maps between these two markers. Three of the patients with severe growth failure (more than 4 SDs below the mean) were hemizygous at the IGF1R locus while the patient with borderline short stature had two copies of the IGF1R; she was subsequently found to be growth hormone deficient and has demonstrated a response to therapy. Our finding of severe short stature correlating with loss of one copy of the IGF1R suggests a potential role for heterozygous IGF1R mutations in other cases of unexplained growth failure.« less

Local small airway epithelial injury induces global smooth muscle contraction and airway constriction

PubMed Central

Zhou, Jian; Alvarez-Elizondo, Martha B.; Botvinick, Elliot

2012-01-01

Small airway epithelial cells form a continuous sheet lining the conducting airways, which serves many functions including a physical barrier to protect the underlying tissue. In asthma, injury to epithelial cells can occur during bronchoconstriction, which may exacerbate airway hyperreactivity. To investigate the role of epithelial cell rupture in airway constriction, laser ablation was used to precisely rupture individual airway epithelial cells of small airways (<300-μm diameter) in rat lung slices (∼250-μm thick). Laser ablation of single epithelial cells using a femtosecond laser reproducibly induced airway contraction to ∼70% of the original cross-sectional area within several seconds, and the contraction lasted for up to 40 s. The airway constriction could be mimicked by mechanical rupture of a single epithelial cell using a sharp glass micropipette but not with a blunt glass pipette. These results suggest that soluble mediators released from the wounded epithelial cell induce global airway contraction. To confirm this hypothesis, the lysate of primary human small airway epithelial cells stimulated a similar airway contraction. Laser ablation of single epithelial cells triggered a single instantaneous Ca2+ wave in the epithelium, and multiple Ca2+ waves in smooth muscle cells, which were delayed by several seconds. Removal of extracellular Ca2+ or decreasing intracellular Ca2+ both blocked laser-induced airway contraction. We conclude that local epithelial cell rupture induces rapid and global airway constriction through release of soluble mediators and subsequent Ca2+-dependent smooth muscle shortening. PMID:22114176

Polycystic ovary syndrome and cardiovascular risk in young patients treated with drospirenone-ethinylestradiol or contraceptive vaginal ring. A prospective, randomized, pilot study.

PubMed

Battaglia, Cesare; Mancini, Fulvia; Fabbri, Raffaella; Persico, Nicola; Busacchi, Paolo; Facchinetti, Fabio; Venturoli, Stefano

2010-09-01

To compare the effects of a pill containing drospirenone with those of a combined contraceptive vaginal ring on the lipid and carbohydrate metabolism and on the surrogate markers of arterial function. Bologna University School of Medicine. Thirty-seven women with polycystic ovary syndrome (PCOS) were randomly submitted to drospirenone+ethinylestradiol (group I; n=19) or combined contraceptive vaginal ring (group II; n=18) therapy. The duration of the study was 6 months. The effect of treatments was assessed after 6 months of therapy. Utero-ovarian ultrasound analysis and color Doppler evaluation of uterine and stromal ovarian arteries. In addition, analysis of brachial artery flow-mediated vasodilatation and 24-hour ambulatory blood pressure monitoring were performed. Fasting blood samples were drawn for testing biochemical and hormonal parameters and nitrites/nitrates. Both treatments improved hirsutism, hyperandrogenemia, and ultrasound and color Doppler ovarian parameters. Both drospirenone+ethinylestradiol or contraceptive vaginal ring induced a slight but significant increase of diurnal and 24-hour blood pressure. Although both therapies worsened the lipid profile, the oral pill administration was associated with a more evident increase of circulating triglycerides. The 6-month treatment with the vaginal ring significantly improved the area under the curve for glucose, insulin, and C-peptide, whereas the drospirenone+ethinylestradiol pill induced an increase in the insulinogenic index and homeostatic model assessment estimate for insulin resistance values. Vaginal hormonal contraception appears to be preferable to oral ethinylestradiol + drospirenone administration in hyperinsulinemic patients with PCOS. Copyright (c) 2010 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

The Cerrillos Uplift, the La Bajada Constriction, and Hydrogeologic Framework of the Santo Domingo Basin, Rio Grande Rift, New Mexico

USGS Publications Warehouse

Minor, Scott A.

2006-01-01

The geologic, geophysical, and hydrogeologic properties of the La Bajada constriction and Santo Domingo Basin, northern New Mexico, result from tectonic and volcanic processes of the late Tertiary and Quaternary Rio Grande rift. An integrated geologic and geophysical assessment in the La Bajada constriction allows development of a geologic framework that can provide input for regional ground-water flow models. These models then can provide better estimates of future water supplies in a region that largely subsists on aquifers in Rio Grande rift basins. The combination of surface geologic investigations (stratigraphic and structural studies; chapters A, B, C, and E), airborne geophysics (aeromagnetic and time-domain electromagnetic surveys; chapters D and F), ground geophysical measurements (gravity and magnetotelluric surveys; chapters D and F), and data from the few wells in the area (chapter G) provides new constraints on the hydrogeologic framework of this area. Summary results of our investigations are synthesized in chapter G. Through-going aquifers consisting of ancestral Rio Grande axial-river sand and gravel and of coarse western-piedmont gravel form the predominant ground-water pathways through the partly buried structural trough defining the La Bajada constriction between Espa?ola and Santo Domingo Basins. Thick, clay-rich Cretaceous marine shales of low hydraulic conductivity form a pervasive regional confining unit within the Cerrillos uplift on the southeast flank of the constriction. Numerous, dominantly north-northwest-striking, intrabasin faults that project part way across the La Bajada constriction create a matrix of laterally and vertically variable hydrogeologic compartments that locally partition and deflect ground-water flow parallel to faults.

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

Diagnostic Challenges in Chronic Constrictive Pericarditis.

PubMed

Braga, Ana; Oliveira, Afonso; Domingues, Kevin; Andrade, Maria João; Abecacis, Miguel; Neves, José Pedro

2017-01-01

Chronic constrictive pericarditis (CCP) is a disease that has multiple possible causes and is associated with variable clinical findings, depending on its severity. It develops insidiously, and in many cases, particularly in developed countries, no antecedent diagnosis can be found. These cases are termed idiopathic. Tuberculosis is the leading cause of constrictive pericarditis in developing nations but represents only a small minority in developed countries. Here the authors describe two different case reports where tuberculosis was the probable cause of CCP. A 21-year-old man born in Cape Verde living in Europe for 4 years and a 24-year-old man born in Guiné Bissau were both admitted due to intense precordial pain and syncope after exertion. Interestingly both had fatigability, dyspnea, chest discomfort and palpitations on exertion, as well as progressive involuntary weight loss and decubitus cough. On physical examination they had tachycardia, jaundice, cachexia, elevated jugular venous pressure, hepatomegaly and ascites. Both electrocardiograms showed prominent P waves and chest X-ray showed bilateral pulmonary interstitial infiltrates and enlargement of the right cavities. Analytically, elevated bilirubin, leukopenia and thrombocytopenia was also found in both. Echocardiography revealed findings, in both cases, compatible with CCP including less common signs as annulus reversus and annulus paradoxus. Thoraco-abdomino-pelvic CT from both patients revealed chronic liver disease with congestion, pleural effusion, pericardial calcifications, ascites and massive mediastinal and abdominal adenopathies. Blood cultures and IGRA test were negative. However, given the presumptive diagnosis of tuberculosis (TB), anti-TB therapy was started. Despite the diagnosis of "end-stage" CCP with very high operative risk multidisciplinary team decided after informed consent, to perform total anterior pericardiectomy, that occurred without complications. Pericardial and

Non-vascularized free toe phalanx transplantation in the treatment of symbrachydactyly and constriction ring syndrome.

PubMed

Gohla, T; Metz, Ch; Lanz, U

2005-10-01

Forty-eight patients underwent a total number of 113 non-vascularized free toe phalanx transplantations for congenital short digits between 1975 and 2003, a mean number of 2.3 transplanted phalanges per patient. The mean age at the time of initial surgery was 3.6 years (range 6 months to 21 years). The follow-up time ranged from 4 months to 14 years with a mean of 6 years. Sixty-four phalanges showed radiographically measured growth, 22 phalanges showed signs of resorption, while 27 phalanges showed neither growth nor resorption. Resorption increased with patient age. Three patients developed donor site problems. The optimum timing for initial surgery is as early as possible because of the safer and greater growth potential and less resorption of the transplanted phalanges. Non-vascularized free toe phalanx transplantations offer a simple and safe method of lengthening with a significant improvement of hand function.

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. © The Author 2014. Published by Oxford University Press on behalf of The Japanese

Reliability of constricted double-heterojunction AlGaAs diode lasers

NASA Technical Reports Server (NTRS)

Botez, D.; Connolly, J. C.; Ettenberg, M.; Gilbert, D. B.; Hughes, J. J.

1983-01-01

Constricted double-heterojunction diode lasers have been life tested at 70 C heatsink temperature and 3-4 mW/facet in CW operation. A median life of 7800 h is obtained at 70 C, which extrapolates to 400,000 h median life at room temperature. The extrapolated mean time to failure at room temperature is in excess of 1,000,000 h. Single-longitudinal-mode CW operation is maintained after 10,000 h of accelerated aging at 70 C.

Constriction of the mitochondrial inner compartment is a priming event for mitochondrial division

PubMed Central

Cho, Bongki; Cho, Hyo Min; Jo, Youhwa; Kim, Hee Dae; Song, Myungjae; Moon, Cheil; Kim, Hyongbum; Kim, Kyungjin; Sesaki, Hiromi; Rhyu, Im Joo; Kim, Hyun; Sun, Woong

2017-01-01

Mitochondrial division is critical for the maintenance and regulation of mitochondrial function, quality and distribution. This process is controlled by cytosolic actin-based constriction machinery and dynamin-related protein 1 (Drp1) on mitochondrial outer membrane (OMM). Although mitochondrial physiology, including oxidative phosphorylation, is also important for efficient mitochondrial division, morphological alterations of the mitochondrial inner-membrane (IMM) have not been clearly elucidated. Here we report spontaneous and repetitive constriction of mitochondrial inner compartment (CoMIC) associated with subsequent division in neurons. Although CoMIC is potentiated by inhibition of Drp1 and occurs at the potential division spots contacting the endoplasmic reticulum, it appears on IMM independently of OMM. Intra-mitochondrial influx of Ca2+ induces and potentiates CoMIC, and leads to K+-mediated mitochondrial bulging and depolarization. Synergistically, optic atrophy 1 (Opa1) also regulates CoMIC via controlling Mic60-mediated OMM–IMM tethering. Therefore, we propose that CoMIC is a priming event for efficient mitochondrial division. PMID:28598422

Theory of vibratory mobilization and break-up of non-wetting fluids entrapped in pore constrictions

NASA Astrophysics Data System (ADS)

Beresnev, I.; Li, W.; Vigil, D.

2006-12-01

Quantitative dynamics of a non-wetting (e. g., NAPL) ganglion entrapped in a pore constriction and subjected to vibrations can be approximated by the equation of motion of an oscillator moving under the effect of the external pressure gradient, inertial oscillatory force, and restoring capillary force. The solution of the equation provides the conditions under which the droplet experiences forced oscillations without being mobilized or is liberated upon the acceleration of the wall exceeding an "unplugging" threshold. This solution provides a quantitative tool for the estimation of the parameters of vibratory fields needed to liberate entrapped non-wetting fluids. For typical pore sizes encountered in reservoirs and aquifers, wall accelerations must exceed at least several m/sec2 and even higher levels to mobilize the droplets of NAPL; however, in the populations of ganglia entrapped in natural porous environments, many may reside very near their mobilization thresholds and may be mobilized by extremely low accelerations as well. For given acceleration, lower seismic frequencies are more efficient. The ganglia may also break up into smaller pieces when passing through pore constrictions. The snap-off is governed by the geometry only; for constrictions with sinusoidal profile (spatial wavelength of L and maximum and minimum radii of rmax and rmin, the break-up occurs if L > 2π(rmin rmax)1/2. Computational fluid dynamics shows the details of the break-up process.

The Characterization of AT1 Expression in the Dorsal Root Ganglia After Chronic Constriction Injury.

PubMed

Oroszova, Zuzana; Hricova, Ludmila; Stropkovska, Andrea; Lukacova, Nadezda; Pavel, Jaroslav

2017-04-01

To clarify the role of Angiotensin II in the regulation of sensory signaling, we characterized the AT 1 expression in neuronal subpopulation of lower lumbar dorsal root ganglia under normal conditions and its alteration in neuropathic pain model. The characterization of AT 1 expression was done under control and after the chronic constriction injury induced by four loose ligatures of the sciatic nerve representing the model of posttraumatic painful peripheral neuropathy. Major Angiotensin II receptor type was expressed in approximately 43 % of small-sized and 62 % of large-sized neurons in control. The AT 1 overexpression after sciatic nerve ligation lasting 7 days was detected predominantly in small-sized AT 1 immunoreactive neurons (about 38 % increase). Chronic constriction injury caused a statistically marked increase in number of the small-sized peptidergic (CGRP immunoreactive) neuronal subpopulation expressing AT 1 (about 64 %). The subpopulations of AT 1 -immunoreactive and nonpeptide-containing primary sensory neurons revealed by IB4 binding, tyrosine hydroxylase- and parvalbumin-immunoreactive neurons were not markedly changed. Our results indicate that: (1) the AT 1 overexpression after the chronic constriction injury is an important factor in Angiotensin II-potentiated pain perception; (2) Angiotensin II is involved in pathological mechanisms of neuropathic pain and this effect can be mediated perhaps in combination with other neuropeptides synthesized in the primary sensory neurons.

The Putative Exchange Factor Gef3p Interacts with Rho3p GTPase and the Septin Ring during Cytokinesis in Fission Yeast*

PubMed Central

Muñoz, Sofía; Manjón, Elvira; Sánchez, Yolanda

2014-01-01

The small GTP-binding proteins of the Rho family and its regulatory proteins play a central role in cytokinetic actomyosin ring assembly and cytokinesis. Here we show that the fission yeast guanine nucleotide exchange factor Gef3p interacts with Rho3p at the division site. Gef3p contains a putative DH homology domain and a BAR/IMD-like domain. The protein localized to the division site late in mitosis, where it formed a ring that did not constrict with actomyosin ring (cytokinetic actomyosin ring) invagination; instead, it split into a double ring that resembled the septin ring. Gef3p co-localized with septins and Mid2p and required septins and Mid2p for its localization. Gef3p interacts physically with the GTP-bound form of Rho3p. Although Gef3p is not essential for cell separation, the simultaneous disruption of gef3+ and Rho3p-interacting proteins, such as Sec8p, an exocyst component, Apm1p, a subunit of the clathrin adaptor complex or For3p, an actin-polymerizing protein, yielded cells with strong defects in septation and polarity respectively. Our results suggest that interactions between septins and Rho-GEFs provide a new targeting mechanism for GTPases in cytokinesis, in this case probably contributing to Rho3p function in vesicle tethering and vesicle trafficking in the later steps of cell separation. PMID:24947517

A New Membrane Protein Sbg1 Links the Contractile Ring Apparatus and Septum Synthesis Machinery in Fission Yeast

PubMed Central

Sethi, Kriti; Palani, Saravanan; Cortés, Juan C. G.; Sato, Mamiko; Sevugan, Mayalagu; Ramos, Mariona; Vijaykumar, Shruthi; Osumi, Masako; Naqvi, Naweed I.; Ribas, Juan Carlos; Balasubramanian, Mohan

2016-01-01

Cytokinesis in many organisms requires a plasma membrane anchored actomyosin ring, whose contraction facilitates cell division. In yeast and fungi, actomyosin ring constriction is also coordinated with division septum assembly. How the actomyosin ring interacts with the plasma membrane and the plasma membrane-localized septum synthesizing machinery remains poorly understood. In Schizosaccharomyces pombe, an attractive model organism to study cytokinesis, the β-1,3-glucan synthase Cps1p / Bgs1p, an integral membrane protein, localizes to the plasma membrane overlying the actomyosin ring and is required for primary septum synthesis. Through a high-dosage suppressor screen we identified an essential gene, sbg1+ (suppressor of beta glucan synthase 1), which suppressed the colony formation defect of Bgs1-defective cps1-191 mutant at higher temperatures. Sbg1p, an integral membrane protein, localizes to the cell ends and to the division site. Sbg1p and Bgs1p physically interact and are dependent on each other to localize to the division site. Loss of Sbg1p results in an unstable actomyosin ring that unravels and slides, leading to an inability to deposit a single contiguous division septum and an important reduction of the β-1,3-glucan proportion in the cell wall, coincident with that observed in the cps1-191 mutant. Sbg1p shows genetic and / or physical interaction with Rga7p, Imp2p, Cdc15p, and Pxl1p, proteins known to be required for actomyosin ring integrity and efficient septum synthesis. This study establishes Sbg1p as a key member of a group of proteins that link the plasma membrane, the actomyosin ring, and the division septum assembly machinery in fission yeast. PMID:27749909

A New Membrane Protein Sbg1 Links the Contractile Ring Apparatus and Septum Synthesis Machinery in Fission Yeast.

PubMed

Sethi, Kriti; Palani, Saravanan; Cortés, Juan C G; Sato, Mamiko; Sevugan, Mayalagu; Ramos, Mariona; Vijaykumar, Shruthi; Osumi, Masako; Naqvi, Naweed I; Ribas, Juan Carlos; Balasubramanian, Mohan

2016-10-01

Cytokinesis in many organisms requires a plasma membrane anchored actomyosin ring, whose contraction facilitates cell division. In yeast and fungi, actomyosin ring constriction is also coordinated with division septum assembly. How the actomyosin ring interacts with the plasma membrane and the plasma membrane-localized septum synthesizing machinery remains poorly understood. In Schizosaccharomyces pombe, an attractive model organism to study cytokinesis, the β-1,3-glucan synthase Cps1p / Bgs1p, an integral membrane protein, localizes to the plasma membrane overlying the actomyosin ring and is required for primary septum synthesis. Through a high-dosage suppressor screen we identified an essential gene, sbg1+ (suppressor of beta glucan synthase 1), which suppressed the colony formation defect of Bgs1-defective cps1-191 mutant at higher temperatures. Sbg1p, an integral membrane protein, localizes to the cell ends and to the division site. Sbg1p and Bgs1p physically interact and are dependent on each other to localize to the division site. Loss of Sbg1p results in an unstable actomyosin ring that unravels and slides, leading to an inability to deposit a single contiguous division septum and an important reduction of the β-1,3-glucan proportion in the cell wall, coincident with that observed in the cps1-191 mutant. Sbg1p shows genetic and / or physical interaction with Rga7p, Imp2p, Cdc15p, and Pxl1p, proteins known to be required for actomyosin ring integrity and efficient septum synthesis. This study establishes Sbg1p as a key member of a group of proteins that link the plasma membrane, the actomyosin ring, and the division septum assembly machinery in fission yeast.

Measurements and simulation of liquid films during drainage displacements and snap-off in constricted capillary tubes.

PubMed

Roman, Sophie; Abu-Al-Saud, Moataz O; Tokunaga, Tetsu; Wan, Jiamin; Kovscek, Anthony R; Tchelepi, Hamdi A

2017-12-01

When a wetting liquid is displaced by air in a capillary tube, a wetting film develops between the tube wall and the air that is responsible for the snap-off mechanism of the gas phase. By dissolving a dye in the wetting phase it is possible to relate a measure of the absorbance in the capillary to the thickness of liquid films. These data could be used to compare with cutting edge numerical simulations of the dynamics of snap-off for which experimental and numerical data are lacking. Drainage experiments in constricted capillary tubes were performed where a dyed wetting liquid is displaced by air for varying flow rates. We developed an optical method to measure liquid film thicknesses that range from 3 to 1000μm. The optical measures are validated by comparison with both theory and direct numerical simulations. In a constricted capillary tube we observed, both experimentally and numerically, a phenomenon of snap-off coalescence events in the vicinity of the constriction that bring new insights into our understanding and modeling of two-phase flows. In addition, the good agreement between experiments and numerical simulations gives confidence to use the numerical method for more complex geometries in the future. Copyright © 2017 Elsevier Inc. All rights reserved.

Role of cardiac output and the autonomic nervous system in the antinatriuretic response to acute constriction of the thoracic superior vena cava.

NASA Technical Reports Server (NTRS)

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

1971-01-01

Study of the differential characteristics of hepatic congestion and decreased cardiac output in terms of potential afferent stimuli in the antinatriuretic effect of acute thoracic inferior vena cava (TIVC) constriction. An attempt is made to see if the autonomic nervous system is involved in the antinatriuretic effect of acute TIVC or thoracic superior vena cava constriction.

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

PubMed

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

2015-07-01

Constricted ear combined with Stahl's ear is a rare ear deformity, which is a kind of complex congenital auricular deformity. From 1 January 2007 to 1 January 2014, 19 patients with constricted ear combined with Stahl's ear (Spock ear) were enrolled in this study, most of which were unilaterally deformed. To correct the deformity, a double Z-shaped skin incision was made on the posterior side of the auricle, with the entire layer of cartilage cut parallel to the helix traversing the third crus to form a fan-shaped cartilage flap. The superior crura of the antihelix were shaped by the folding cartilage rim. The cartilage of the abnormal third crus was made part of the new superior crura of antihelix, and the third crus was eliminated. The postoperative aesthetic assessment of the reshaped auricle was graded by both doctors and patients (or their parents). Out of the 19 patients, the number of satisfying cases of the symmetry, helix stretch, elimination of the third crus, the cranioauricular angle, and the substructure of the reshaped ears was 14 (nine excellent and five good), 16 (six excellent and 10 good), 17 (eight excellent and nine good), 15 (five excellent and 10 good), and 13 (two excellent and 11 good), respectively. With a maximum of a 90-month follow-up, no complication was observed. The results of the study suggested that this rare deformity could be corrected by appropriate surgical treatment, with a satisfied postoperative appearance. Copyright © 2015 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Tumbling cartilage flap and free auricular composite tissue transplantation for correcting mild and moderate forms of constricted ear.

PubMed

Pan, Bo; Zhao, Yanyong; Zhuang, Hongxing; Lin, Lin; Liu, Lei; Jiang, Haiyue

2010-01-01

To report a new surgical approach that results in a natural size and contour of the external malformed constricted ear. A total of 62 consecutive patients with constricted ear underwent surgery between July 1, 2005, and December 31, 2007. Depending on the features and severity of the deformity, the methods of tumbling cartilage flap (CF), free auricular composite graft, or a combination of these 2 techniques were applied. A total of 45 patients were treated with the method of tumbling CF. Twelve were treated with an auricular composite graft from the contralateral ear, and in 5 patients a combination of the 2 methods was used. In all cases, there was an improvement in the size, shape, and symmetry of the ears, and most patients were satisfied with the outcome. Complications were rare, and there was no donor site deformity. The technique of tumbling CF and free auricular composite graft provides a simple and promising treatment for constricted ears. Furthermore, this technique is easy to apply with a predictable good outcome.

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

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

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

Single cell rheometry with a microfluidic constriction: Quantitative control of friction and fluid leaks between cell and channel walls

PubMed Central

Preira, Pascal; Valignat, Marie-Pierre; Bico, José; Théodoly, Olivier

2013-01-01

We report how cell rheology measurements can be performed by monitoring the deformation of a cell in a microfluidic constriction, provided that friction and fluid leaks effects between the cell and the walls of the microchannels are correctly taken into account. Indeed, the mismatch between the rounded shapes of cells and the angular cross-section of standard microfluidic channels hampers efficient obstruction of the channel by an incoming cell. Moreover, friction forces between a cell and channels walls have never been characterized. Both effects impede a quantitative determination of forces experienced by cells in a constriction. Our study is based on a new microfluidic device composed of two successive constrictions, combined with optical interference microscopy measurements to characterize the contact zone between the cell and the walls of the channel. A cell squeezed in a first constriction obstructs most of the channel cross-section, which strongly limits leaks around cells. The rheological properties of the cell are subsequently probed during its entry in a second narrower constriction. The pressure force is determined from the pressure drop across the device, the cell velocity, and the width of the gutters formed between the cell and the corners of the channel. The additional friction force, which has never been analyzed for moving and constrained cells before, is found to involve both hydrodynamic lubrication and surface forces. This friction results in the existence of a threshold for moving the cells and leads to a non-linear behavior at low velocity. The friction force can nevertheless be assessed in the linear regime. Finally, an apparent viscosity of single cells can be estimated from a numerical prediction of the viscous dissipation induced by a small step in the channel. A preliminary application of our method yields an apparent loss modulus on the order of 100 Pa s for leukocytes THP-1 cells, in agreement with the literature data. PMID:24404016

Pediatric constrictive asphyxia a rare form of child abuse: A report of two cases.

PubMed

Vester, M E M; Bilo, R A C; Nijs, H G T; van Rijn, R R

2018-04-01

We present two cases of infants who died under suspicious circumstances. After clinical and legal investigations, non-accidental constrictive asphyxia inflicted by one of the parents was established. The first case presents a to date not yet reported, unique mechanism of trauma. In order to stop his daughter from crying, the father admitted that he sometimes sat on his baby while she was lying on the bed. Occasionally increasing his force by pulling with his hands on the bottom of the bed. In the second case tight swaddling and encircling chest compression was the causative mechanism. In both cases the father was sentenced to imprisonment with mandate psychiatric care. Only two previous reports of this uncommon and relatively unknown cause of child abuse, called constrictive asphyxia, are known. In all reported cases static loading of the chest resulted in rib fractures and demise of the child. This rare abusive mechanism should be known to pediatric radiologists and pathologists. Copyright © 2018 Elsevier B.V. All rights reserved.

Homozygous deficiency of ubiquitin-ligase ring-finger protein RNF168 mimics the radiosensitivity syndrome of ataxia-telangiectasia

PubMed Central

Devgan, S S; Sanal, O; Doil, C; Nakamura, K; Nahas, S A; Pettijohn, K; Bartek, J; Lukas, C; Lukas, J; Gatti, R A

2011-01-01

Maintaining genomic integrity is critical to avoid life-threatening disorders, such as premature aging, neurodegeneration and cancer. A multiprotein cascade operates at sites of DNA double-strand breaks (DSBs) to recognize, signal and repair damage. RNF168 (ring-finger nuclear factor) contributes to this emerging pathway of several E3 ubiquitin ligases that perform sequential ubiquitylations on damaged chromosomes, chromatin modifications essential for aggregation of repair complexes at the DSB sites. Here, we report the clinical and cellular phenotypes associated with a newly identified homozygous nonsense mutation in the RNF168 gene of a patient with a syndrome mimicking ataxia-telangiectasia. The mutation eliminated both of RNF168's ubiquitin-binding motifs, thus blocking progression of the ubiquitylation cascade and retention of repair proteins including tumor suppressors 53BP1 and BRCA1 at DSB sites, consistent with the observed defective DNA damage checkpoints/repair and pronounced radiosensitivity. Rapid screening for RNF168 pathway deficiency was achieved by scoring patients' lymphoblastoid cells for irradiation-induced nuclear foci containing 53BP1, a robust assay we propose for future diagnostic applications. The formation of radiation-induced DSB repair foci was rescued by ectopic expression of wild-type RNF168 in patient's cells, further causally linking the RNF168 mutation with the pathology. Clinically, this novel syndrome featured ataxia, telangiectasia, elevated alphafetoprotein, immunodeficiency, microcephaly and pulmonary failure and has implications for the differential diagnosis of autosomal recessive ataxias. PMID:21394101

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.

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.

Saturn's Rings and Associated Ring Plasma Cavity: Evidence for Slow Ring Erosion

NASA Technical Reports Server (NTRS)

Farrell, W. M.; Kurth, W. S.; Gurnett, D. A.; Persoon, A. M.; MacDowall, R. J.

2017-01-01

We re-examine the radio and plasma wave observations obtained during the Cassini Saturn orbit insertion period, as the spacecraft flew over the northern ring surface into a radial distance of 1.3 Rs (over the C-ring). Voyager era studies suggest the rings are a source of micro-meteoroid generated plasma and dust, with theorized peak impact-created plasma outflows over the densest portion of the rings (central B-ring). In sharp contrast, the Cassini Radio and Plasma Wave System (RPWS) observations identify the presence of a ring-plasma cavity located in the central portion of the B-ring, with little evidence of impact-related plasma. While previous Voyager era studies have predicted unstable ion orbits over the C- ring, leading to field-aligned plasma transport to Saturns ionosphere, the Cassini RPWS observations do not reveal evidence for such instability-created plasma fountains. Given the passive ring loss processes observed by Cassini, we find that the ring lifetimes should extend >10(exp 9) years, and that there is limited evidence for prompt destruction (loss in <100 Myrs).

Saturn's rings and associated ring plasma cavity: Evidence for slow ring erosion

NASA Astrophysics Data System (ADS)

Farrell, W. M.; Kurth, W. S.; Gurnett, D. A.; Persoon, A. M.; MacDowall, R. J.

2017-08-01

We re-examine the radio and plasma wave observations obtained during the Cassini Saturn orbit insertion period, as the spacecraft flew over the northern ring surface into a radial distance of 1.3 Rs (over the C-ring). Voyager era studies suggest the rings are a source of micro-meteoroid generated plasma and dust, with theorized peak impact-created plasma outflows over the densest portion of the rings (central B-ring). In sharp contrast, the Cassini Radio and Plasma Wave System (RPWS) observations identify the presence of a ring-plasma cavity located in the central portion of the B-ring, with little evidence of impact-related plasma. While previous Voyager era studies have predicted unstable ion orbits over the C-ring, leading to field-aligned plasma transport to Saturn's ionosphere, the Cassini RPWS observations do not reveal evidence for such instability-created plasma 'fountains'. Given the passive ring loss processes observed by Cassini, we find that the ring lifetimes should extend >109 years, and that there is limited evidence for prompt destruction (loss in <100 Myrs).

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.

Amniotic Band Syndrome: A Review of 2 Cases.

PubMed

Madan, Siddharth; Chaudhuri, Zia

2018-04-03

Amniotic band syndrome is a rare congenital disorder caused by entrapment of fetal parts (usually a limb or digits) in fibrous amniotic bands while in utero that presents with complex multisystem anomalies. The authors report 2 children with amniotic band syndrome who presented to the ophthalmic unit of the authors' pediatric hospital. One of them presented with telecanthus, syndactyly, amputated toes, and unilateral epiphora diagnosed as congenital nasolacrimal duct obstruction. She was managed conservatively with lacrimal sac massage and provided with refractive correction while she simultaneously underwent multiple surgeries for correction of clubfoot and craniosynostosis. The second patient presented with cleft lip, cleft palate, multiple constriction bands in upper limbs and fingers with unilateral microphthalmos, microcornea, typical iris coloboma, and retinochoroidal coloboma, very similar to a case reported in literature. These 2 cases provide an overview of the clinical spectrum of ophthalmic manifestations along with their staged optimum rehabilitation.

Placento-Cranial Adhesions in Amniotic Band Syndrome and the Role of Surgery in Their Management: An Unusual Case Presentation and Systematic Literature Review.

PubMed

Menekse, Guner; Mert, Mustafa Kurthan; Olmaz, Burak; Celik, Tamer; Celik, Umit Sizmaz; Okten, Ali Ihsan

2015-01-01

Amniotic band syndrome is a group of sporadic congenital anomalies that involve the limbs, craniofacial regions and trunk, ranging from simple digital band constriction to complex craniofacial and central nervous system abnormalities. Placento-cranial adhesions in amniotic band syndrome are extremely rare, and severe conditions are associated with high morbidity and mortality rates. In this study, we pooled placento-cranial adhesion case reports that were published in the medical literature and added an unpublished case from our institution. The purpose of this article was to review and discuss the clinical features and outcomes of placento-cranial adhesions in amniotic band syndrome. © 2015 S. Karger AG, Basel.

Anillin acts as a bifunctional linker coordinating midbody ring biogenesis during cytokinesis

PubMed Central

Kechad, Amel; Jananji, Silvana; Ruella, Yvonne; Hickson, Gilles R. X.

2013-01-01

Summary Animal cell cytokinesis proceeds via constriction of an actomyosin-based contractile ring (CR) [1, 2]. Upon reaching a diameter of ~1 μm [3], a midbody ring (MR) forms to stabilize the intercellular bridge until abscission [4-6]. How MR formation is coupled to CR closure and how plasma membrane anchoring is maintained at this key transition is unknown. Time-lapse microscopy of Drosophila S2 cells depleted of the scaffold protein, Anillin [7-9], revealed that Anillin is required for complete closure of the CR and formation of the MR. Truncation analysis revealed that Anillin N-termini connected with the actomyosin CR and supported formation of stable MR-like structures, but these could not maintain anchoring of the plasma membrane. Conversely, Anillin C-termini failed to connect with the CR or MR but recruited the septin, Peanut, to ectopic structures at the equatorial cortex. Peanut depletion mimicked truncation of the Anillin C-terminus, resulting in MR-like structures that failed to anchor the membrane. These data demonstrate that Anillin coordinates the transition from CR to MR, and that it does so by linking two distinct cortical cytoskeletal elements. One apparently acts as the core structural template for MR assembly, while the other ensures stable anchoring of the plasma membrane beyond the CR stage. PMID:22226749

Artificially lengthened and constricted vocal tract in vocal training methods.

PubMed

Bele, Irene Velsvik

2005-01-01

It is common practice in vocal training to make use of vocal exercise techniques that involve partial occlusion of the vocal tract. Various techniques are used; some of them form an occlusion within the front part of the oral cavity or at the lips. Another vocal exercise technique involves lengthening the vocal tract; for example, the method of phonation into small tubes. This essay presents some studies made on the effects of various vocal training methods that involve an artificially lengthened and constricted vocal tract. The influence of sufficient acoustic impedance on vocal fold vibration and economical voice production is presented.

Test of the movement expansion model: Anticipatory vowel lip protrusion and constriction in French and English speakers

PubMed Central

Noiray, Aude; Cathiard, Marie-Agnès; Ménard, Lucie; Abry, Christian

2011-01-01

The modeling of anticipatory coarticulation has been the subject of longstanding debates for more than 40 yr. Empirical investigations in the articulatory domain have converged toward two extreme modeling approaches: a maximal anticipation behavior (Look-ahead model) or a fixed pattern (Time-locked model). However, empirical support for any of these models has been hardly conclusive, both within and across languages. The present study tested the temporal organization of vocalic anticipatory coarticulation of the rounding feature from [i] to [u] transitions for adult speakers of American English and Canadian French. Articulatory data were synchronously recorded using an Optotrak for lip protrusion and a dedicated Lip-Shape-Tracking-System for lip constriction. Results show that (i) protrusion is an inconsistent parameter for tracking anticipatory rounding gestures across individuals, more specifically in English; (ii) labial constriction (between-lip area) is a more reliable correlate, allowing for the description of vocalic rounding in both languages; (iii) when tested on the constriction component, speakers show a lawful anticipatory behavior expanding linearly as the intervocalic consonant interval increases from 0 to 5 consonants. The Movement Expansion Model from Abry and Lallouache [(1995a) Bul. de la Comm. Parlée 3, 85–99; (1995b) Proceedings of ICPHS4, 152–155.] predicted such a regular behavior, i.e., a lawful variabilitywith a speaker-specific expansion rate, which is not language-specific. PMID:21303015

Test of the movement expansion model: anticipatory vowel lip protrusion and constriction in French and English speakers.

PubMed

Noiray, Aude; Cathiard, Marie-Agnès; Ménard, Lucie; Abry, Christian

2011-01-01

The modeling of anticipatory coarticulation has been the subject of longstanding debates for more than 40 yr. Empirical investigations in the articulatory domain have converged toward two extreme modeling approaches: a maximal anticipation behavior (Look-ahead model) or a fixed pattern (Time-locked model). However, empirical support for any of these models has been hardly conclusive, both within and across languages. The present study tested the temporal organization of vocalic anticipatory coarticulation of the rounding feature from [i] to [u] transitions for adult speakers of American English and Canadian French. Articulatory data were synchronously recorded using an Optotrak for lip protrusion and a dedicated Lip-Shape-Tracking-System for lip constriction. Results show that (i) protrusion is an inconsistent parameter for tracking anticipatory rounding gestures across individuals, more specifically in English; (ii) labial constriction (between-lip area) is a more reliable correlate, allowing for the description of vocalic rounding in both languages; (iii) when tested on the constriction component, speakers show a lawful anticipatory behavior expanding linearly as the intervocalic consonant interval increases from 0 to 5 consonants. The Movement Expansion Model from Abry and Lallouache [(1995a) Bul. de la Comm. Parlée 3, 85-99; (1995b) Proceedings of ICPHS 4, 152-155.] predicted such a regular behavior, i.e., a lawful variability with a speaker-specific expansion rate, which is not language-specific.

Scaling down constriction-based (electrodeless) dielectrophoresis devices for trapping nanoscale bioparticles in physiological media of high-conductivity.

PubMed

Chaurey, Vasudha; Rohani, Ali; Su, Yi-Hsuan; Liao, Kuo-Tang; Chou, Chia-Fu; Swami, Nathan S

2013-04-01

Selective trapping of nanoscale bioparticles (size <100 nm) is significant for the separation and high-sensitivity detection of biomarkers. Dielectrophoresis is capable of highly selective trapping of bioparticles based on their characteristic frequency response. However, the trapping forces fall steeply with particle size, especially within physiological media of high-conductivity where the trapping can be dissipated by electrothermal (ET) flow due to localized Joule heating. Herein, we investigate the influence of device scaling within the electrodeless insulator dielectrophoresis geometry through the application of highly constricted channels of successively smaller channel depth, on the net balance of dielectrophoretic trapping force versus ET drag force on bioparticles. While higher degrees of constriction enable dielectrophoretic trapping of successively smaller bioparticles within a short time, the ETflow due to enhanced Joule heating within media of high conductivity can cause a significant dissipation of bioparticle trapping. This dissipative drag force can be reduced through lowering the depth of the highly constricted channels to submicron sizes, which substantially reduces the degree of Joule heating, thereby enhancing the range of voltages and media conductivities that can be applied toward rapid dielectrophoretic concentration enrichment of silica nanoparticles (∼50 nm) and streptavidin protein biomolecules (∼5 nm). We envision the application of these methodologies toward nanofabrication, optofluidics, biomarker discovery, and early disease diagnostics. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DPD simulation on the dynamics of a healthy and infected red blood cell in flow through a constricted channel

NASA Astrophysics Data System (ADS)

Hoque, Sazid Zamal; Anand, D. Vijay; Patnaik, B. S. V.

2017-11-01

The state of the red blood cell (either healthy or infected RBC) will influence its deformation dynamics. Since the pathological condition related to RBC, primarily originates from a single cell infection, therefore, it is important to relate the deformation dynamics to the mechanical properties (such as, bending rigidity and membrane elasticity). In the present study, numerical simulation of a healthy and malaria infected RBC in a constricted channel is analyzed. The flow simulations are carried out using finite sized dissipative particle dynamics (FDPD) method in conjunction with a discrete model that represents the membrane of the RBC. The numerical equivalent of optical tweezers test is validated against the experimental studies. Two different types of constrictions, viz., a converging-diverging type tapered channel and a stenosed microchannel are considered for the simulation. The effect of degree of constriction and the flow rate effect on the RBC is investigated. It was observed that, as the flow rate decreases, the infected RBC completely blocks the micro vessel. The transit time for infected cell drastically increases compared to healthy RBC. Our simulations indicate that, there is a critical flow rate below which infected RBC cannot pass through the micro capillary.

The stapled hemorrhoidopexy syndrome: a new clinical entity?

PubMed

Efthimiadis, Chr; Kosmidis, Chr; Grigoriou, M; Anthimidis, G; Vasiliadou, K; Baka, S; Gerasimidou, D; Basdanis, G

2011-10-01

Haemorrhoidal disease is a rather common disease of unknown cause. A new technique for treating prolapsing haemorrhoids known as the stapled hemorrhoidopexy (SH) or the "Longo procedure" is widely used. Serious adverse events were reported in 2000 and some discussion over the syndrome but nothing since. Two hundred and five patients underwent SH by our surgical team at the Interbalkan European Medical Center. Modified SH was performed. Despite the low incidence of postoperative complications (11/205), 36.58% of patients developed syndrome comprised of urgency to defecate, sensation of anal foreign body and incomplete defecation and mild cramp like anal discomfort, immediately after surgery or in the following 48 h. There is not statistically significant relationship between the presence of the syndrome and the gender, the presence of muscle fibres in the resected "ring" the degree of haemorrhoidal disease, age and ring length. Observations led us to conclude that the stapled hemorrhoidopexy syndrome (SHS) is probably caused by the irritating presence of the titanium staples in the rectal mucosa and by the resection itself.

A spinal thecal sac constriction model supports the theory that induced pressure gradients in the cord cause edema and cyst formation.

PubMed

Josephson, A; Greitz, D; Klason, T; Olson, L; Spenger, C

2001-03-01

Spinal cord cysts are a devastating condition that occur secondary to obstructions of the spinal canal, which may be caused by congenital malformations, trauma, spinal canal stenosis, tumors, meningitis, or arachnoiditis. A hypothesis that could explain how spinal cord cysts form in these situations has been presented recently. Therefore, a novel spinal thecal sac constriction model was implemented to test various aspects of this hypothesis. Thecal sac constriction was achieved by subjecting rats to an extradural silk ligature at the T8 spinal cord level. Rats with complete spinal cord transection served as a second model for comparison. The animals underwent high-resolution magnetic resonance imaging and histological analysis. Thecal sac constriction caused edema cranial and caudal to the ligation within 3 weeks, and cysts developed after 8 to 13 weeks. In contrast, cysts in rats with spinal cord transection were located predominantly in the cranial spinal cord. Histological sections of spinal cords confirmed the magnetic resonance imaging results. Magnetic resonance imaging provided the specific advantage of enabling characterization of events as they occurred repeatedly over time in the spinal cords of individual living animals. The spinal thecal sac constriction model proved useful for investigation of features of the cerebrospinal fluid pulse pressure theory. Edema and cyst distributions were in accordance with this theory. We conclude that induced intramedullary pressure gradients originating from the cerebrospinal fluid pulse pressure may underlie cyst formation in the vicinity of spinal canal obstructions and that cysts are preceded by edema.

Report of the eRHIC Ring-Ring Working Group

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aschenauer, E. C.; Berg, S.; Blaskiewicz, M.

2015-10-13

This report evaluates the ring-ring option for eRHIC as a lower risk alternative to the linac-ring option. The reduced risk goes along with a reduced initial luminosity performance. However, a luminosity upgrade path is kept open. This upgrade path consists of two branches, with the ultimate upgrade being either a ring-ring or a linac-ring scheme. The linac-ring upgrade could be almost identical to the proposed linac-ring scheme, which is based on an ERL in the RHIC tunnel. This linac-ring version has been studied in great detail over the past ten years, and its significant risks are known. On the othermore » hand, no detailed work on an ultimate performance ring-ring scenario has been performed yet, other than the development of a consistent parameter set. Pursuing the ring-ring upgrade path introduces high risks and requires significant design work that is beyond the scope of this report.« less

Airway constriction in asthma during sustained emotional stimulation with films.

PubMed

Ritz, Thomas; Rosenfield, David; Wilhelm, Frank H; Roth, Walton T

2012-09-01

Individuals with asthma have been shown to respond to unpleasant stimuli with bronchoconstriction, but little is known about the time course of responding during sustained emotional stimulation and whether it varies with patients' experience. To examine the time course of oscillatory resistance (R(os)) during emotionally evocative films in 15 asthma patients and 14 healthy controls. Participants viewed unpleasant, surgery, and neutral films, each ranging 3-5min in duration. R(os) and the respiratory pattern (respiration rate, tidal volume, minute ventilation) were monitored continuously. Following each film, participants rated their affective response and symptoms. The time course of R(os) during films was explored using multilevel modeling. Compared to neutral film sequences, unpleasant films (including those with surgery scenes) elicited a uniform pattern of initial increases in R(os) with peaks within the first 1-2min, followed by a gradual decline. Increases were more pronounced in asthma and during surgery films. Including additional respiratory parameters as time-varying covariates did not affect the temporal course of R(os) change. The rate of decline in R(os) (after the initial increase) was less in participants who experienced greater arousal and in patients who reported more shortness of breath. Patients more susceptible to psychological triggers in daily life showed slower rates of decline in R(os). The temporal course of bronchoconstriction to unpleasant stimulation is highly uniform in asthma, with strong constriction in early stages of stimulation. More sustained constriction in emotion-induced asthma could be a risk factor for developing asthma exacerbation in daily life. Copyright © 2012 Elsevier B.V. All rights reserved.

Constrictive Bronchiolitis in Cystic Fibrosis Adolescents with Refractory Pulmonary Decline.

PubMed

Harris, William T; Boyd, J Todd; McPhail, Gary L; Brody, Alan S; Szczesniak, Rhonda D; Korbee, Leslie L; Baker, Michael L; Clancy, John P

2016-12-01

Refractory lung function decline in association with recurrent pulmonary exacerbations is a common, yet poorly explained finding in cystic fibrosis (CF). To investigate the histopathologic mechanisms of pulmonary deterioration during adolescence and early adulthood, we reviewed clinically-indicated lung biopsy specimens obtained during a period of persistent decline. To determine if peribronchiolar remodeling is prominent in lung biopsy specimens obtained in adolescents with CF refractory to conventional therapy. Six adolescents with CF (mean age, 16.2 y; mean FEV 1 , 52% predicted at biopsy) with significant pulmonary deterioration over 12-24 months (mean FEV 1 decline of 14% predicted/year) despite aggressive intervention underwent computed tomography imaging and ultimately lung biopsy to aid clinical management. In addition to routine clinical evaluation, histopathologic investigation included staining for transforming growth factor-β (TGF-β, a genetic modifier of CF lung disease), collagen deposition (a marker of fibrosis), elastin (to evaluate for bronchiectasis), and α-smooth muscle actin (to identify myofibroblasts). All computed tomography scans demonstrated a mix of bronchiectasis and hyperinflation that was variable across lung regions and within patients. Lung biopsy revealed significant peribronchiolar remodeling, particularly in patients with more advanced disease, with near complete obliteration of the peribronchiolar lumen (constrictive bronchiolitis). Myofibroblast differentiation (a TGF-β-dependent process) was prominent in specimens with significant airway remodeling. Constrictive bronchiolitis is widely present in the lung tissue of adolescents with CF with advanced disease and may contribute to impaired lung function that is refractory to conventional therapy (antibiotics, antiinflammatories, and mucolytics). TGF-β-dependent myofibroblast differentiation is prominent in areas of active fibrogenesis and may foster small airway remodeling in

Differentiation of Constriction and Restriction: Complex Cardiovascular Hemodynamics.

PubMed

Geske, Jeffrey B; Anavekar, Nandan S; Nishimura, Rick A; Oh, Jae K; Gersh, Bernard J

2016-11-29

Differentiation of constrictive pericarditis (CP) from restrictive cardiomyopathy (RCM) is a complex and often challenging process. Because CP is a potentially curable cause of heart failure and therapeutic options for RCM are limited, distinction of these 2 conditions is critical. Although different in regard to etiology, prognosis, and treatment, CP and RCM share a common clinical presentation of predominantly right-sided heart failure, in the absence of significant left ventricular systolic dysfunction or valve disease, due to impaired ventricular diastolic filling. Fundamental to the diagnosis of either condition is a clear understanding of the underlying hemodynamic principles and pathophysiology. We present a contemporary review of the pathophysiology, hemodynamics, diagnostic assessment, and therapeutic approach to patients presenting with CP and RCM. Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

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

Low-threshold high-T/0/ constricted double heterojunction AlGaAs diode lasers

NASA Technical Reports Server (NTRS)

Botez, D.; Connolly, J. C.

1980-01-01

Constricted double heterojunction diode lasers of relatively low CW thresholds (28-40 mA) are obtained by growing structures that maximize the amount of current flow into the lasing spot. These values are obtained while still using standard 10 microns wide oxide-defined stripe contacts. Over the 20-70 C temperature interval, threshold current temperature coefficients as high as 320 C and a virtually constant external differential quantum efficiency, are found.

The contribution of bends and constrictions of a superconducting film to the photon detection by a single-photon superconducting detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zotova, A. N., E-mail: zotova@imp.sci-nnov.ru

2016-05-15

The contribution of bends and constrictions by a superconducting film to the detection by a single photon superconducting detector is investigated. It has been shown that, for currents smaller than the minimal detection current of a straight film, the detection efficiency of a film with a constriction attains saturation upon an increase in the current, which coincides qualitatively with the behavior of this dependence observed in the experiment. It has also been found that the effect of bends in the film and the external magnetic field on the detection efficiency for low-energy photons is essential, while for high-energy photons nomore » such influence is observed.« less

Planetary Rings

NASA Astrophysics Data System (ADS)

Tiscareno, Matthew S.

Planetary rings are the only nearby astrophysical disks and the only disks that have been investigated by spacecraft (especially the Cassini spacecraft orbiting Saturn). Although there are significant differences between rings and other disks, chiefly the large planet/ring mass ratio that greatly enhances the flatness of rings (aspect ratios as small as 10- 7), understanding of disks in general can be enhanced by understanding the dynamical processes observed at close range and in real time in planetary rings.We review the known ring systems of the four giant planets, as well as the prospects for ring systems yet to be discovered. We then review planetary rings by type. The A, B, and C rings of Saturn, plus the Cassini Division, comprise our solar system's only dense broad disk and host many phenomena of general application to disks including spiral waves, gap formation, self-gravity wakes, viscous overstability and normal modes, impact clouds, and orbital evolution of embedded moons. Dense narrow rings are found both at Uranus (where they comprise the main rings entirely) and at Saturn (where they are embedded in the broad disk) and are the primary natural laboratory for understanding shepherding and self-stability. Narrow dusty rings, likely generated by embedded source bodies, are surprisingly found to sport azimuthally confined arcs at Neptune, Saturn, and Jupiter. Finally, every known ring system includes a substantial component of diffuse dusty rings.Planetary rings have shown themselves to be useful as detectors of planetary processes around them, including the planetary magnetic field and interplanetary impactors as well as the gravity of nearby perturbing moons. Experimental rings science has made great progress in recent decades, especially numerical simulations of self-gravity wakes and other processes but also laboratory investigations of coefficient of restitution and spectroscopic ground truth. The age of self-sustained ring systems is a matter of

Subadditive responses to extremely short blue and green pulsed light on visual evoked potentials, pupillary constriction and electroretinograms.

PubMed

Lee, Soomin; Uchiyama, Yuria; Shimomura, Yoshihiro; Katsuura, Tetsuo

2017-11-17

The simultaneous exposure to blue and green light was reported to result in less melatonin suppression than monochromatic exposure to blue or green light. Here, we conducted an experiment using extremely short blue- and green-pulsed light to examine their visual and nonvisual effects on visual evoked potentials (VEPs), pupillary constriction, electroretinograms (ERGs), and subjective evaluations. Twelve adult male subjects were exposed to three light conditions: blue-pulsed light (2.5-ms pulse width), green-pulsed light (2.5-ms pulse width), and simultaneous blue- and green-pulsed light with white background light. We measured the subject's pupil diameter three times in each condition. Then, after 10 min of rest, the subject was exposed to the same three light conditions. We measured the averaged ERG and VEP during 210 pulsed-light exposures in each condition. We also determined subjective evaluations using a visual analog scale (VAS) method. The pupillary constriction during the simultaneous exposure to blue- and green-pulsed light was significantly lower than that during the blue-pulsed light exposure despite the double irradiance intensity of the combination. We also found that the b/|a| wave of the ERGs during the simultaneous exposure to blue- and green-pulsed light was lower than that during the blue-pulsed light exposure. We confirmed the subadditive response to pulsed light on pupillary constriction and ERG. However, the P100 of the VEPs during the blue-pulsed light were smaller than those during the simultaneous blue- and green-pulsed light and green-pulsed light, indicating that the P100 amplitude might depend on the luminance of light. Our findings demonstrated the effect of the subadditive response to extremely short pulsed light on pupillary constriction and ERG responses. The effects on ipRGCs by the blue-pulsed light exposure are apparently reduced by the simultaneous irradiation of green light. The blue versus yellow (b/y) bipolar cells in the

Visual Outcomes in Japanese Patients with Retinitis Pigmentosa and Usher Syndrome Caused by USH2A Mutations.

PubMed

Nagase, Yasunori; Kurata, Kentaro; Hosono, Katsuhiro; Suto, Kimiko; Hikoya, Akiko; Nakanishi, Hiroshi; Mizuta, Kunihiro; Mineta, Hiroyuki; Minoshima, Shinsei; Hotta, Yoshihiro

2017-07-05

EYS and USH2A are the most common causative genes for retinitis pigmentosa (RP) in Japan. We determined the clinical outcomes for USH2A-related non-syndromic RP or Usher syndrome type II (USH2). Two non-syndromic RP and 11 USH2 patients with previously identified USH2A mutations were included. Their complete history and medical records were collected using standard procedures. Visual fields and acuity were compared with those of patients with EYS mutations. Clinical analyses were based on ophthalmic and otolaryngologic examinations. In all patients, the fundus displayed changes typical of RP. Most patients showed relatively well-preserved visual acuity in their thirties or forties, with rapid deterioration in their fifties. Concentric constriction started in the twenties or thirties, and no effective residual visual field was observed after the fifties. The visual outcome for non-syndromic RP or USH2 patients with USH2A mutations is consistent with that for RP patients with EYS mutations.

Impending gangrene of fingers by constriction bands of mother's hair mistaken as pernio by parents: A case series of 10 infants.

PubMed

Bhat, Towseef Ahmad; Ali, Zameer; Moten, Tarseem Lal; Sofi, Aabid Hussain; Mir, Furqaan; Gulzar, Amara

2017-01-01

Long harsh winter in Kashmir Valley increase the incidence of pernio in children so much that common people consider every hand swelling as pernio. 10 Infants over two years were brought to our hospital as cases of pernio involving fingers. All the infants came out to be cases of impending gangrene due to mother's hair as constriction bands around fingers. Impending gangrene of fingers in infants due to mother hair as constriction band is very rare. However its symptoms overlap with symptoms of peripheral cold injuries and can be easily mistaken for each other by people.

Division and dynamic morphology of plastids.

PubMed

Osteryoung, Katherine W; Pyke, Kevin A

2014-01-01

Plastid division is fundamental to the biology of plant cells. Division by binary fission entails the coordinated assembly and constriction of four concentric rings, two internal and two external to the organelle. The internal FtsZ ring and external dynamin-like ARC5/DRP5B ring are connected across the two envelopes by the membrane proteins ARC6, PARC6, PDV1, and PDV2. Assembly-stimulated GTPase activity drives constriction of the FtsZ and ARC5/DRP5B rings, which together with the plastid-dividing rings pull and squeeze the envelope membranes until the two daughter plastids are formed, with the final separation requiring additional proteins. The positioning of the division machinery is controlled by the chloroplast Min system, which confines FtsZ-ring formation to the plastid midpoint. The dynamic morphology of plastids, especially nongreen plastids, is also considered here, particularly in relation to the production of stromules and plastid-derived vesicles and their possible roles in cellular communication and plastid functionality.

Integrally Closed Rings

NASA Astrophysics Data System (ADS)

Tuganbaev, A. A.

1982-04-01

This paper studies integrally closed rings. It is shown that a semiprime integrally closed Goldie ring is the direct product of a semisimple artinian ring and a finite number of integrally closed invariant domains that are classically integrally closed in their (division) rings of fractions. It is shown also that an integrally closed ring has a classical ring of fractions and is classically integrally closed in it.Next, integrally closed noetherian rings are considered. It is shown that an integrally closed noetherian ring all of whose nonzero prime ideals are maximal is either a quasi-Frobenius ring or a hereditary invariant domain.Finally, those noetherian rings all of whose factor rings are invariant are described, and the connection between integrally closed rings and distributive rings is examined.Bibliography: 13 titles.

Mapping Ring Particle Cooling across Saturn's Rings with Cassini CIRS

NASA Astrophysics Data System (ADS)

Brooks, Shawn M.; Spilker, L. J.; Edgington, S. G.; Pilorz, S. H.; Deau, E.

2010-10-01

Previous studies have shown that the rings' thermal inertia, a measure of their response to changes in the thermal environment, varies from ring to ring. Thermal inertia can provide insight into the physical structure of Saturn's ring particles and their regoliths. Low thermal inertia and quick temperature responses are suggestive of ring particles that have more porous or fluffy regoliths or that are riddled with cracks. Solid, coherent particles can be expected to have higher thermal inertias (Ferrari et al. 2005). Cassini's Composite Infrared Spectrometer has recorded millions of spectra of Saturn's rings since its arrival at Saturn in 2004 (personal communication, M. Segura). CIRS records far infrared radiation between 10 and 600 cm-1 (16.7 and 1000 µm) at focal plane 1 (FP1), which has a field of view of 3.9 mrad. Thermal emission from Saturn's rings peaks in this wavelength range. FP1 spectra can be used to infer ring temperatures. By tracking how ring temperatures vary, we can determine the thermal inertia of the rings. In this work we focus on CIRS observations of the shadowed portion of Saturn's rings. The thermal budget of the rings is dominated by the solar radiation absorbed by its constituent particles. When ring particles enter Saturn's shadow this source of energy is abruptly cut off. As a result, ring particles cool as they traverse Saturn's shadow. From these shadow observations we can create cooling curves at specific locations across the rings. We will show that the rings' cooling curves and thus their thermal inertia vary not only from ring to ring, but by location within the individual rings. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2010 California Institute of Technology. Government sponsorship acknowledged.

Ring dynamics

NASA Technical Reports Server (NTRS)

Borderies, Nicole

1989-01-01

Theoretical models of planetary-ring dynamics are discussed in a detailed analytical review and illustrated with graphs and diagrams. The streamline concept is introduced, and the phenomena associated with the transport of angular momentum are described. Particular attention is then given to (1) broad rings like those of Saturn (shepherding, density-wave excitation, gaps, bending-wave excitation, multiringlet structures, inner-edge shepherding, and the possibility of polar rings around Neptune), (2) narrow rings like those of Uranus (shepherding, ring shapes, and a self-gravity model of rigid precession), and (3) ring arcs like those seen in stellar-occultation observations of Neptune.

Cardiomyocyte binucleation is associated with aberrant mitotic microtubule distribution, mislocalization of RhoA and IQGAP3, as well as defective actomyosin ring anchorage and cleavage furrow ingression.

PubMed

Leone, Marina; Musa, Gentian; Engel, Felix Benedikt

2018-03-07

After birth mammalian cardiomyocytes initiate a last cell cycle which results in binucleation due to cytokinesis failure. Despite its importance for cardiac regenerative therapies, this process is poorly understood. Here, we aimed at a better understanding of the difference between cardiomyocyte proliferation and binucleation, and providing a new tool to distinguish these two processes. Monitoring of cell division by time-lapse imaging revealed that rat cardiomyocyte binucleation stems from a failure to properly ingress the cleavage furrow. Astral microtubule required for actomyosin ring anchorage and thus furrow ingression were not symmetrically distributed at the periphery of the equatorial region during anaphase in binucleating cardiomyocytes. Consequently, RhoA, the master regulator of actomyosin ring formation and constriction, non-muscle myosin IIB, a central component of the actomyosin ring, as well as IQGAP3 were abnormally localized during cytokinesis. In agreement with improper furrow ingression, binucleation in vitro as well as in vivo was associated with a failure of RhoA as well as IQGAP3 to localize to the stembody of the midbody. Taken together, these results indicate that naturally occurring cytokinesis failure in primary cardiomyocytes is due to an aberrant mitotic microtubule apparatus resulting in inefficient anchorage of the actomyosin ring to the plasma cell membrane. Thus, cardiomyocyte binucleation and division can be discriminated by the analysis of RhoA as well as IQGAP3 localization.

The 22q13.3 Deletion Syndrome (Phelan-McDermid Syndrome)

PubMed Central

Phelan, K.; McDermid, H.E.

2012-01-01

The 22q13.3 deletion syndrome, also known as Phelan-McDermid syndrome, is a contiguous gene disorder resulting from deletion of the distal long arm of chromosome 22. In addition to normal growth and a constellation of minor dysmorphic features, this syndrome is characterized by neurological deficits which include global developmental delay, moderate to severe intellectual impairment, absent or severely delayed speech, and neonatal hypotonia. In addition, more than 50% of patients show autism or autistic-like behavior, and therefore it can be classified as a syndromic form of autism spectrum disorders (ASD). The differential diagnosis includes Angelman syndrome, velocardiofacial syndrome, fragile X syndrome, and FG syndrome. Over 600 cases of 22q13.3 deletion syndrome have been documented. Most are terminal deletions of ∼100 kb to >9 Mb, resulting from simple deletions, ring chromosomes, and unbalanced translocations. Almost all of these deletions include the gene SHANK3 which encodes a scaffold protein in the postsynaptic densities of excitatory synapses, connecting membrane-bound receptors to the actin cytoskeleton. Two mouse knockout models and cell culture experiments show that SHANK3 is involved in the structure and function of synapses and support the hypothesis that the majority of 22q13.3 deletion syndrome neurological defects are due to haploinsufficiency of SHANK3, although other genes in the region may also play a role in the syndrome. The molecular connection to ASD suggests that potential future treatments may involve modulation of metabotropic glutamate receptors. PMID:22670140

Myosin VI and branched actin filaments mediate membrane constriction and fission of melanosomal tubule carriers.

PubMed

Ripoll, Léa; Heiligenstein, Xavier; Hurbain, Ilse; Domingues, Lia; Figon, Florent; Petersen, Karl J; Dennis, Megan K; Houdusse, Anne; Marks, Michael S; Raposo, Graça; Delevoye, Cédric

2018-06-06

Vesicular and tubular transport intermediates regulate organellar cargo dynamics. Transport carrier release involves local and profound membrane remodeling before fission. Pinching the neck of a budding tubule or vesicle requires mechanical forces, likely exerted by the action of molecular motors on the cytoskeleton. Here, we show that myosin VI, together with branched actin filaments, constricts the membrane of tubular carriers that are then released from melanosomes, the pigment containing lysosome-related organelles of melanocytes. By combining superresolution fluorescence microscopy, correlative light and electron microscopy, and biochemical analyses, we find that myosin VI motor activity mediates severing by constricting the neck of the tubule at specific melanosomal subdomains. Pinching of the tubules involves the cooperation of the myosin adaptor optineurin and the activity of actin nucleation machineries, including the WASH and Arp2/3 complexes. The fission and release of these tubules allows for the export of components from melanosomes, such as the SNARE VAMP7, and promotes melanosome maturation and transfer to keratinocytes. Our data reveal a new myosin VI- and actin-dependent membrane fission mechanism required for organelle function. © 2018 Ripoll et al.

Occult constrictive pericardial disease emerging 40 years after chest radiation therapy: a case report.

PubMed

Goten, Chiaki; Murai, Hisayoshi; Takashima, Shin-Ichiro; Kato, Takeshi; Usui, Soichiro; Furusho, Hiroshi; Saeki, Takahiro; Sakagami, Satoru; Takemura, Hirofumi; Kaneko, Shuichi; Takamura, Masayuki

2018-05-31

The main etiology of constrictive pericarditis (CP) has changed from tuberculosis to therapeutic mediastinal radiation and cardiac surgery. Occult constrictive pericardial disease (OCPD) is a covert disease in which CP is manifested in a condition of volume overload. A 60-year-old patient with a history of thoracic radiation therapy for non-Hodgkin's lymphoma (40 years earlier) was transferred to our hospital for treatment of repeated congestive heart failure. For a preoperative hemodynamic study, pre-hydration with intravenous normal saline (50 mL/hour) was used to manifest the pericardial disease and prevent contrast-induced nephropathy. The hemodynamic study showed a right ventricular dip-plateau pattern and discordance of right and left ventricular systolic pressures during inspiration, which was not seen in the volume-controlled state. These responses were concordant with OCPD. A pericardiectomy, aortic valve replacement, and mitral and tricuspid valve repair were performed. Postoperatively, the heart failure was controlled with standard medication. This case revealed a volume-induced change in hemodynamics in OCPD with severe combined valvular heart disease, which suggests the importance of considering OCPD in patients who had undergone radiation therapy 40 years before.

[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.

Cognitive Machine-Learning Algorithm for Cardiac Imaging: A Pilot Study for Differentiating Constrictive Pericarditis From Restrictive Cardiomyopathy.

PubMed

Sengupta, Partho P; Huang, Yen-Min; Bansal, Manish; Ashrafi, Ali; Fisher, Matt; Shameer, Khader; Gall, Walt; Dudley, Joel T

2016-06-01

Associating a patient's profile with the memories of prototypical patients built through previous repeat clinical experience is a key process in clinical judgment. We hypothesized that a similar process using a cognitive computing tool would be well suited for learning and recalling multidimensional attributes of speckle tracking echocardiography data sets derived from patients with known constrictive pericarditis and restrictive cardiomyopathy. Clinical and echocardiographic data of 50 patients with constrictive pericarditis and 44 with restrictive cardiomyopathy were used for developing an associative memory classifier-based machine-learning algorithm. The speckle tracking echocardiography data were normalized in reference to 47 controls with no structural heart disease, and the diagnostic area under the receiver operating characteristic curve of the associative memory classifier was evaluated for differentiating constrictive pericarditis from restrictive cardiomyopathy. Using only speckle tracking echocardiography variables, associative memory classifier achieved a diagnostic area under the curve of 89.2%, which improved to 96.2% with addition of 4 echocardiographic variables. In comparison, the area under the curve of early diastolic mitral annular velocity and left ventricular longitudinal strain were 82.1% and 63.7%, respectively. Furthermore, the associative memory classifier demonstrated greater accuracy and shorter learning curves than other machine-learning approaches, with accuracy asymptotically approaching 90% after a training fraction of 0.3 and remaining flat at higher training fractions. This study demonstrates feasibility of a cognitive machine-learning approach for learning and recalling patterns observed during echocardiographic evaluations. Incorporation of machine-learning algorithms in cardiac imaging may aid standardized assessments and support the quality of interpretations, particularly for novice readers with limited experience. © 2016

Planetary rings as relics of plasma pre-rings

NASA Astrophysics Data System (ADS)

Rabinovich, B. I.

2007-02-01

A possibility is discussed that the rings of large planets observed in the modern epoch are relics of some pre-rings consisting of magnetized plasma (according to a hypothesis by H. Alfven). The solution to a model problem published in [36, 37] is used. Its main result is a mechanism of stratification of an evolutionally mature plasma pre-ring into a large number of narrow elite rings separated by anti-rings (gaps). Another result is the theoretical substantiation of the presence in the near-planetary space of a region of existence and stability (in what follows it is referred to as ES-region) of plasma rings. The data obtained in the course of the Voyager, Galileo, and Cassini missions are used below for verification of the model on which the solutions presented in [36, 37] are based.

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.

Mechanisms of leukotriene D4-induced constriction in human small bronchioles

PubMed Central

Snetkov, V A; Hapgood, K J; McVicker, C G; Lee, T H; Ward, J P T

2001-01-01

We examined the mechanisms underlying leukotriene D4- (LTD4) induced constriction of human small (300 – 500 μm i.d.) bronchioles, and the effect of LTD4 on ion currents and Ca2+ transients in smooth muscle cells (SMC) isolated from these bronchioles. LTD4 caused a concentration-dependent bronchoconstriction with an EC50=0.58±0.05 nM (n=7) which was not easily reversible upon washout. This bronchoconstriction was entirely dependent on extracellular Ca2+. Blockade of L-type Ca2+ channels with nifedipine (10 μM) reduced LTD4 response by 39±2% (n=8), whilst La3+, Gd3+ and SK&F 96,365 abolished LTD4-induced bronchoconstriction completely and reversibly, suggesting the majority of Ca2+ entry was via non-selective cation channels. Antagonists of PI-PLC (U73,122 and ET-18-OCH3), PLD (propranolol) and PKC (cheleretrine and Ro31-8220) were without any effect on LTD4-induced bronchoconstriction, whilst the PC-PLC inhibitor D609 caused complete relaxation. Inhibition of protein tyrosine kinase with tyrphostin A23 (100 μM) caused about 50% relaxation, although the inactive analogue tyrphostin A1 was without effect. In freshly isolated SMC from human small bronchioles LTD4 caused a slow increase of intracellular Ca2+ concentration, with a consequent rise of the activity of large conductance Ca2+-dependent K+ channels and the amplitude of depolarization-induced outward whole-cell current. Again, no effect of LTD4 could be observed in the absence of extracellular Ca2+. We conclude that LTD4 causes constriction of these small bronchioles primarily by activating Ca2+ entry via non-voltage gated channels, possibly by a PC-PLC mediated pathway. PMID:11350860

[A case of mosaic ring chromosome 4 with subtelomeric 4p deletion].

PubMed

Kim, Jeong Hyun; Oh, Phil Soo; Na, Hye Yeon; Kim, Sun-Hee; Cho, Hyoun Chan

2009-02-01

Ring chromosome is a structural abnormality that is thought to be the result of fusion and breakage in the short and long arms of chromosome. Wolf-Hirschhorn syndrome (WHS) is a well-known congenital anomaly in the ring chromosome 4 with a partial deletion of the distal short arm. Here we report a 10-month-old male of mosaic ring chromosome 4 with the chief complaint of severe short stature. He showed the height of -4 standard deviation, subtle hypothyroidism and mild atrial septal defect/ventricular septal defect, and also a mild language developmental delay was suspected. Brain magnetic resonance imaging showed multifocal leukomalacia. Chromosomal analysis of the peripheral blood showed the mosaic karyotype with [46,XY,r(4)(p16q35)[84]/45,XY,-4[9]/91,XXYY, dic r(4;4)(p16q35;p16q35)[5]/46,XY,dic r(4;4)(p16q35;p16q35)[2

Saturn's Rings, the Yarkovsky Effects, and the Ring of Fire

NASA Technical Reports Server (NTRS)

Rubincam, David

2004-01-01

Saturn's icy ring particles, with their low thermal conductivity, are almost ideal for the operation of the Yarkovsky effects. The dimensions of Saturn's A and B rings may be determined by a near balancing of the seasonal Yarkovsky effect with the Yarkovsky- Schach effect. The two effects, which are photon thrust due to temperature gradients, may confine the A and B rings to within their observed dimensions. The C ring may be sparsely populated with icy particles because Yarkovsky drag has pulled them into Saturn, leaving the more slowly orbitally decaying rocky particles. Icy ring particles ejected from the B ring and passing through the C ring, as well as some of the slower rocky particles, should fall on Saturn's equator, where they may create a luminous "Ring of Fire" around Saturn's equator. This predicted Ring of Fire may be visible to Cassini's camera. Curiously, the speed of outwards Yarkovsky orbital evolution appears to peak near the Cassini Division. The connection between the two is not clear. D. Nesvorny has speculated that the resonance at the outer edge of the B ring may impede particles from evolving via Yarkovsky across the Division. If supply from the B ring is largely cut off, then Yarkovsky may push icy particles outward, away from the inner edge of the A ring, leaving only the rocky ones in the Division. The above scenarios depend delicately on the properties of the icy particles.

Variations in Ring Particle Cooling across Saturn's Rings with Cassini CIRS

NASA Astrophysics Data System (ADS)

Brooks, S. M.; Spilker, L. J.; Pilorz, S.; Edgington, S. G.; Déau, E.; Altobelli, N.

2010-12-01

Cassini's Composite Infrared Spectrometer has recorded over two million of spectra of Saturn's rings in the far infrared since arriving at Saturn in 2004. CIRS records far infrared radiation between 10 and 600 cm-1 ( 16.7 and 1000 μ {m} ) at focal plane 1 (FP1), which has a field of view of 3.9 mrad. Thermal emission from Saturn’s rings peaks in this wavelength range. Ring temperatures can be inferred from FP1 data. By tracking how ring temperatures vary, we can determine the thermal inertia of the rings. Previous studies have shown that the rings' thermal inertia, a measure of their response to changes in the thermal environment, varies from ring to ring. Thermal inertia can provide insight into the physical structure of Saturn's ring particles and their regoliths. Low thermal inertia and rapidly changing temperatures are suggestive of ring particles that have more porous or fluffy regoliths or that are riddled with cracks. Solid particles can be expected to have higher thermal inertias. Ferrari et al. (2005) fit thermal inertia values of 5218 {Jm)-2 {K}-1 {s}-1/2 to their B ring data and 6412 {Jm)-2 {K}-1 {s}-1/2 to their C ring data. In this work we focus on CIRS observations of the shadowed portion of Saturn's rings. The rings’ thermal budget is dominated by its absorption of solar radiation. As a result, ring particles abruptly cool as they traverse Saturn's shadow. From these shadow observations we can create cooling curves at specific locations across the rings. We will show that the rings' cooling curves and thus their thermal inertia vary not only from ring to ring, but by location within the individual rings. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2010 California Institute of Technology. Government sponsorship acknowledged.

Vortex rings

NASA Technical Reports Server (NTRS)

Shariff, Karim; Leonard, Anthony

1992-01-01

The vortex-ring problem in fluid mechanics is examined generally in terms of formation, the steady state, the duration of the rings, and vortex interactions. The formation is studied by examining the generation of laminar and turbulent vortex rings and their resulting structures with attention given to the three stages of laminar ring development. Inviscid dynamics is addressed to show how core dynamics affects overall ring motion, and laminar vortex structures are described in two dimensions. Viscous and inviscid structures are related in terms of 'leapfrogging', head-on collisions, and collisions with a no-slip wall. Linear instability theory is shown to successfully describe observational data, although late stages in the breakdown are not completely understood. This study of vortex rings has important implications for key aerodynamic issues including sound generation, transport and mixing, and vortex interactions.

A novel bronchial ring bioassay for the evaluation of small airway smooth muscle function in mice.

PubMed

Liu, John Q; Yang, Dennis; Folz, Rodney J

2006-08-01

Advances in our understanding of murine airway physiology have been hindered by the lack of suitable, ex vivo, small airway bioassay systems. In this study, we introduce a novel small murine airway bioassay system that permits the physiological and pharmacological study of intrapulmonary bronchial smooth muscle via a bronchial ring (BR) preparation utilizing BR segments as small as 200 microm in diameter. Using this ex vivo BR bioassay, we characterized small airway smooth muscle contraction and relaxation in the presence and absence of bronchial epithelium. In control BRs, the application of mechanical stretch is followed by spontaneous bronchial smooth muscle relaxation. BRs pretreated with methacholine (MCh) partially attenuate this stretch-induced relaxation by as much as 42% compared with control. MCh elicited a dose-dependent bronchial constriction with a maximal tension (E(max)) of 8.7 +/- 0.2 mN at an EC(50) of 0.33 +/- 0.02 microM. In the presence of nifedipine, ryanodine, 2-aminoethoxydiphenyl borate, and SKF-96365, E(max) to MCh was significantly reduced. In epithelium-denuded BRs, MCh-induced contraction was significantly enhanced to 11.4 +/- 1.0 mN with an EC(50) of 0.16 +/- 0.04 microM (P < 0.01). Substance P relaxed MCh-precontracted BR by 62.1%; however, this bronchial relaxation effect was completely lost in epithelium-denuded BRs. Papaverine virtually abolished MCh-induced constriction in both epithelium-intact and epithelium-denuded bronchial smooth muscle. In conclusion, this study introduces a novel murine small airway BR bioassay that allows for the physiological study of smooth muscle airway contractile responses that may aid in our understanding of the pathophysiology of asthma.

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.

Concentric ring flywheel with hooked ring carbon fiber separator/torque coupler

DOEpatents

Kuklo, Thomas C.

1999-01-01

A concentric ring flywheel with expandable separators, which function as torque couplers, between the rings to take up the gap formed between adjacent rings due to differential expansion between different radius rings during rotation of the flywheel. The expandable separators or torque couplers include a hook-like section at an upper end which is positioned over an inner ring and a shelf-like or flange section at a lower end onto which the next adjacent outer ring is positioned. As the concentric rings are rotated the gap formed by the differential expansion there between is partially taken up by the expandable separators or torque couplers to maintain torque and centering attachment of the concentric rings.

Concentric ring flywheel with hooked ring carbon fiber separator/torque coupler

DOEpatents

Kuklo, T.C.

1999-07-20

A concentric ring flywheel with expandable separators, which function as torque couplers, between the rings to take up the gap formed between adjacent rings due to differential expansion between different radius rings during rotation of the flywheel. The expandable separators or torque couplers include a hook-like section at an upper end which is positioned over an inner ring and a shelf-like or flange section at a lower end onto which the next adjacent outer ring is positioned. As the concentric rings are rotated the gap formed by the differential expansion there between is partially taken up by the expandable separators or torque couplers to maintain torque and centering attachment of the concentric rings. 2 figs.

[Metastatic signet ring cell carcinoma to the breast from stomach].

PubMed

Krichen Makni, S; Abbes, K; Khanfir, A; Frikha, M; Sellami Boudawara, T

2007-09-01

Metastatic tumors in the breast are quite rare and constitute 0.5 to 6% of all breast malignancies. They often occur in a polymetastatic context. The most frequent primitive tumors are lymphoma, leukaemia and malignant melanoma. The gastric origin is seldom reported. We report here the observation of a 40-years woman operated in urgency for an acute abdominal syndrome. A gastric tumor was discovered intraoperatively with ovarian metastasis and peritoneal carcinosis. The pathological examination revealed a gastric signet ring cell carcinoma with an infiltration of the right ovary. Four months later, the patient presented with a lump of the right breast. The histologic examination corresponded to a mammary metastasis by a signet ring cell carcinoma from stomach. The objective of our work is to discuss through this observation the anatomoclinical and evolutionary characteristics of breast metastasis.

THE STATE OF THE VESSELS OF THE MESENTERY IN SHOCK PRODUCED BY CONSTRICTING THE LIMBS AND THE BEHAVIOR OF THE VESSELS FOLLOWING HEMORRHAGE

PubMed Central

Page, Irvine H.; Abell, Richard G.

1943-01-01

1. Direct observations of the arteries, arterioles, capillaries, veins, and lymphatics in the mesentery of anesthetized cats put into shock by incomplete occlusion of the circulation of the limbs showed that: (a) Marked constriction of the arteries and arterioles, produced by muscular contraction, occurred usually within an hour after incomplete occlusion of the limbs, lasted several hours, and finally gave way in most instances to relaxation an hour or more before death. The constriction reduced the blood supply to the mesentery and intestine and the venous return from them. It did not, however, interrupt the blood flow. No pooling or stagnation of blood was seen even as a terminal phenomenon. (b) The veins of the mesentery also became constricted but showed less tendency to dilate as death approached. The lymphatics likewise became somewhat narrowed. Even during the terminal stage the leukocytes moved along without change in shape or sticking to the walls of the capillaries or venules. (c) Hematocrit determinations showed progressive hemoconcentration of moderate degree. (d) Autopsy usually showed the presence of small hemorrhages in many parts of the body, especially the heart, liver, spleen, and lungs. (e) Bilateral nephrectomy, suprarenalectomy, and pancreatectomy did not significantly alter the morphological picture elicited by shock induced by restriction of the circulation to the limbs. 2. Removal of large amounts of blood was always followed within a short time by constriction of arteries, arterioles, veins, and lymphatics of the mesentery. 3. Fall in arterial pressure produced by pithing was not accompanied by change in diameter of the arteries, arterioles, veins, or lymphatics, or by blanching of the mesentery or gut. PMID:19871278

Ag+ alters cell growth, neurite extension, cardiomyocyte beating, and fertilized egg constriction.

PubMed

Conrad, A H; Tramp, C R; Long, C J; Wells, D C; Paulsen, A Q; Conrad, G W

1999-11-01

The Russian Space Agency uses electrochemically generated silver ions (Ag+) to purify drinking water for their space station, Mir, and their portion of the International Space Station. U.S. EPA guidelines allow 10.6 micromol x L(-1) Ag+ in human drinking water for up to 10 d. Studies correlate Ag+ exposure with tissue dysfunction in humans, rats, and mice, and with altered ion transport, skeletal muscle contraction, and embryonic cell constriction in other animal cells. Ag+ effects on cell shape change-related functions have not been assessed. Immortalized embryonic human intestinal epithelial cells, freshly explanted embryonic avian nerve cells and cardiomyocytes, and marine fertilized eggs were grown in vitro in medium containing AgNO3. Intestinal cells detach from the substratum and viable cell number decreases by 5-6 d at 5 micromol x L(-1) AgNO3, and faster at higher concentrations. Microtubules appear unaltered in adherent cells. Detached cells are nonviable. Neurite outgrowth and glial cell migration from dorsal root ganglia are inhibited by 3 d at 15 micromol x L(-1) AgNO3 or greater. Contractions stop temporarily in most cardiomyocytes by 5 min at 5 micromol x L(-1) AgNO3 or more, but some cardiomyocytes beat 3 times faster than normal at 7.5-20 micromol x L(-1) AgNO3. Picomolar Ag+ increases marine egg polar lobe constriction within an hour, even in the absence of microtubules. Ag+ alters animal cell growth and shape changes by a MT-independent mechanism. This is the first report of Ag+ effects on vertebrate neurite outgrowth, glial cell migration, or cardiomyocyte beat rate.

Saturn's Rings, the Yarkovsky Effects, and the Ring of Fire

NASA Technical Reports Server (NTRS)

Rubincam, David Parry

2004-01-01

The dimensions of Saturn's A and B rings may be determined by the seasonal Yarkovsky effect and the Yarkovsky-Schach effect; the two effects confine the rings between approximately 1.68 and approximately 2.23 Saturn radii, in reasonable agreement with the observed values of 1.525 and 2.267. The C ring may be sparsely populated because its particles are transients on their way to Saturn; the infall may create a luminous Ring of Fire around Saturn's equator. The ring system may be young: in the past heat flow from Saturn's interior much above its present value would not permit rings to exist.

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.

Slowing down of ring polymer diffusion caused by inter-ring threading.

PubMed

Lee, Eunsang; Kim, Soree; Jung, YounJoon

2015-06-01

Diffusion of long ring polymers in a melt is much slower than the reorganization of their internal structures. While direct evidence for entanglements has not been observed in the long ring polymers unlike linear polymer melts, threading between the rings is suspected to be the main reason for slowing down of ring polymer diffusion. It is, however, difficult to define the threading configuration between two rings because the rings have no chain end. In this work, evidence for threading dynamics of ring polymers is presented by using molecular dynamics simulation and applying a novel analysis method. The simulation results are analyzed in terms of the statistics of persistence and exchange times that have proved useful in studying heterogeneous dynamics of glassy systems. It is found that the threading time of ring polymer melts increases more rapidly with the degree of polymerization than that of linear polymer melts. This indicates that threaded ring polymers cannot diffuse until an unthreading event occurs, which results in the slowing down of ring polymer diffusion. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Median nerve constrictive operation combined with tendon transfer to treat brain paralysis convulsive deformity of hand].

PubMed

Ma, Shanjun; Zhou, Tianjian

2014-05-01

To evaluate the effectiveness of the median nerve constrictive operation combined with tendon transfer to treat the brain paralysis convulsive deformity of the hand. The clinical data from 21 cases with brain paralysis convulsive deformity of the hand were analyzed retrospectively between August 2009 and April 2012. Of them, there were 13 males and 8 females with an average age of 15 years (range, 10-29 years). The causes of the convulsive cerebral palsy included preterm deliveries in 11 cases, hypoxia asphyxia in 7, traumatic brain injury in 2, and encephalitis sequela in 1. The disease duration was 2-26 years (mean, 10.6 years). All the 21 patients had cock waists, crooking fingers, and contracture of adductors pollicis, 12 had the forearm pronation deformity. According to Ashworth criteria, there were 2 cases at level I, 5 cases at level II, 8 cases at level III, 4 cases at level IV, and 2 cases at level V. All patients had no intelligence disturbances. The forearm X-ray film showed no bone architectural changes before operation. The contraction of muscle and innervation was analyzed before operation. The median nerve constrictive operation combined with tendon transfer was performed. The functional activities and deformity improvement were evaluated during follow-up. After operation, all the patients' incision healed by first intension, without muscle atrophy and ischemic spasm. All the 21 cases were followed up 1.5-4.5 years (mean, 2.3 years). No superficial sensory loss occurred. The effectiveness was excellent in 13 cases, good in 6 cases, and poor in 2 cases, with an excellent and good rate of 90.4% at last follow-up. The median nerve constrictive operation combined with tendon transfer to treat brain paralysis convulsive deformity of the hand can remove and prevent the recurrence of spasm, achieve the orthopedic goals, to assure the restoration of motor function and the improvement of the life quality.

Uranus Tenth Ring

NASA Image and Video Library

1996-01-29

On Jan. 23, 1986, NASA Voyager 2 discovered a tenth ring orbiting Uranus. The tenth ring is about midway between the bright, outermost epsilon ring and the next ring down, called delta. http://photojournal.jpl.nasa.gov/catalog/PIA00035

Jupiter Ring Halo

NASA Image and Video Library

1998-03-26

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 (km) per picture element (pixel) along the rings; however, 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 2,300,000 kilometers (km) away. The arc on the far right of the image is produced by sunlight 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, which lies exterior to 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 far left side of the figure. 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. A faint mist of particles can be seen above and below the main rings; this vertically extended, toroidal "halo" is unusual in planetary rings, and is probably caused by electromagnetic forces which can push small grains out of the ring plane. Halo material is present across this entire image, implying that it reaches more than 27,000 km above the ring plane. Because of shadowing, the halo is not visible close to Jupiter in the lower right part of the mosaic. In order to accentuate faint features in the image, different brightnesses are shown through color, with the brightest being

Birth Control Ring

MedlinePlus

... Safe Videos for Educators Search English Español Birth Control Ring KidsHealth / For Teens / Birth Control Ring What's in this article? What Is It? ... Anillo vaginal anticonceptivo What Is It? The birth control ring is a soft, flexible, doughnut-shaped ring ...

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

Chest Wall Constriction after the Nuss Procedure Identified from Chest Radiograph and Multislice Computed Tomography Shortly after Removal of the Bar.

PubMed

Chang, Pei-Yeh; Zeng, Qi; Wong, Kin-Sun; Wang, Chao-Jan; Chang, Chee-Jen

2016-01-01

This study radiographically examined the changes in the chest walls of patients with pectus excavatum (PE) after Nuss bar removal, to define the deformation caused by the bar and stabilizer. In the first part of the study, we compared the changes in chest radiographs of patients with PE to a preoperation PE control group. In the second part, we used multislice computed tomography (CT) scans to provide three-dimensional reconstructions with which to evaluate the changes to the thoracic wall. Part 1 From June 2006 to August 2011, 1,125 patients with PE who had posteroanterior chest radiographs taken before undergoing the Nuss procedure at four hospitals were enrolled as a preoperative control group. At the same time, 203 patients who had the bar removed were enrolled as the study group. The maximum dimensions of the outer boundary of the first to ninth rib pairs (R1-R9, rib pair width), chest height, and chest width were measured. Part 2 Thirty-one consecutive patients with PE (20 males and 11 females) who underwent Nuss bar removal were evaluated 7 to 30 days after operation. During this period, a further 34 patients with PE who had undergone CT imaging before bar insertion were evaluated and compared with the postoperative group. Part 1 The width of the lower ribs (R4-R9) after bar removal was significantly less than in the age-matched controls. The ribs adjacent to the bar (R5-R7) showed the greatest restriction. The width of the upper ribs (R1-R3) 2 to 3 years after bar placement did not differ significantly from the controls. Patients who were operated on after 10 years of age had less of a restrictive effect. Three years of bar placement resulted in more restriction than a 2-year period, particularly in patients younger than 10 years old. Part 2: A significant constriction of the chest wall was observed in 13 patients after removal of the Nuss bar. Constriction at ribs 5 to 8 was found to be present adjacent to the site of bar insertion. However

The Saturn Ring Observer: In situ studies of planetary rings

NASA Astrophysics Data System (ADS)

Nicholson, P. D.; Tiscareno, M. S.; Spilker, L. J.

2010-12-01

As part of the Planetary Science Decadal Survey recently undertaken by the NRC's Space Studies Board for the National Academy of Sciences, studies were commissioned for a number of potential missions to outer planet targets. One of these studies examined the technological feasibility of a mission to carry out in situ studies of Saturn's rings, from a spacecraft placed in a circular orbit above the ring plane: the Saturn Ring Observer. The technical findings and background are discussed in a companion poster by T. R. Spilker et al. Here we outline the science goals of such a mission. Most of the fundamental interactions in planetary rings occur on spatial scales that are unresolved by flyby or orbiter spacecraft. Typical particle sizes in the rings of Saturn are in the 1 cm - 10 m range, and average interparticle spacings are a few meters. Indirect evidence indicates that the vertical thickness of the rings is as little as 5 - 10 m, which implies a velocity dispersion of only a few mm/sec. Theories of ring structure and evolution depend on the unknown characteristics of interparticle collisions and on the size distribution of the ring particles. The SRO could provide direct measurements of both the coefficient of restitution -- by monitoring individual collisions -- and the particles’ velocity dispersion. High-resolution observations of individual ring particles should also permit estimates of their spin states. Numerical simulations of Saturn’s rings incorporating both collisions and self-gravity predict that the ring particles are not uniformly distributed, but are instead clustered into elongated structures referred to as “self-gravity wakes”, which are continually created and destroyed on an orbital timescale. Theory indicates that the average separation between wakes in the A ring is of order 30-100 m. Direct imaging of self-gravity wakes, including their formation and subsequent dissolution, would provide critical validation of these models. Other

Jupiter's Main Ring

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 (km) per picture element (pixel) along the rings; however, 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 2,300,000 kilometers (km) away. The arc on the far right of the image is produced by sunlight 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, which lies exterior to 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 far left side of the figure. 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. 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.

Jupiter's main ring is a thin strand of material encircling the planet. The diffuse innermost boundary begins at approximately 123,000 km. The main ring's outer radius is found to be

Analytical and Design Study for a High-Pressure, High-Enthalpy Constricted Arc Heater

DTIC Science & Technology

1975-07-01

Stabilized Constricted Arc," NASA Technical Memorandum X-2700, February 1973. Nikuradse, J., "Gesetzm~ssigkeit der turbulenten Str ~ mung in glatten...REFERENCES FOR APPENDIX C Nikuradse, J., "Gesetzm~ssigkeit der turbulenten Str ~ mung in glatten Rohren, °’ Forschungsheft 356 (1932). Watson, V. R. and...qlI) NiT|U/pus| H& STR ~Uol] •G#S ~el~ • *SRbO0(-O• -hOR?RX~*ll -.R IO||•E*O • *) , •?•?l [*SO |.bRS8A[-aS -?~Oq~T•F~aa |5••A~?F*It - ] .~O~t [ -R2

New insights into FtsZ rearrangements during the cell division of Escherichia coli from single-molecule localization microscopy of fixed cells.

PubMed

Vedyaykin, Alexey D; Vishnyakov, Innokentii E; Polinovskaya, Vasilisa S; Khodorkovskii, Mikhail A; Sabantsev, Anton V

2016-06-01

FtsZ - a prokaryotic tubulin homolog - is one of the central components of bacterial division machinery. At the early stage of cytokinesis FtsZ forms the so-called Z-ring at mid-cell that guides septum formation. Many approaches were used to resolve the structure of the Z-ring, however, researchers are still far from consensus on this question. We utilized single-molecule localization microscopy (SMLM) in combination with immunofluorescence staining to visualize FtsZ in Esherichia coli fixed cells that were grown under slow and fast growth conditions. This approach allowed us to obtain images of FtsZ structures at different stages of cell division and accurately measure Z-ring dimensions. Analysis of these images demonstrated that Z-ring thickness increases during constriction, starting at about 70 nm at the beginning of division and increasing by approximately 25% half-way through constriction. © 2016 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Jupiter's ring

NASA Technical Reports Server (NTRS)

1979-01-01

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

The vertical structure of the F ring of Saturn from ring-plane crossings

NASA Astrophysics Data System (ADS)

Scharringhausen, Britt R.; Nicholson, Philip D.

2013-11-01

We present a photometric model of the rings of Saturn which includes the main rings and an F ring, inclined to the main rings, with a Gaussian vertical profile of optical depth. This model reproduces the asymmetry in brightness between the east and west ansae of the rings of Saturn that was observed by the Hubble Space Telescope (HST) within a few hours after the Earth ring-plane crossing (RPX) of 10 August 1995. The model shows that during this observation the inclined F ring unevenly blocked the east and west ansae of the main rings. The brightness asymmetry produced by the model is highly sensitive to the vertical thickness and radial optical depth of the F ring. The F-ring model that best matches the observations has a vertical full width at half maximum of 13 ± 7 km and an equivalent depth of 10 ± 4 km. The model also reproduces the shape of the HST profiles of ring brightness vs. distance from Saturn, both before and after the time of ring-plane crossing. Smaller asymmetries observed before the RPX, when the Earth was on the dark side of the rings, cannot be explained by blocking of the main rings by the F ring or vice versa and are probably instead due to the intrinsic longitudinal variation exhibited by the F ring.

Etude des sequences de type consonne constrictive plus voyelle en francais, a l'aide de la radiocinematographie et de l'oscillographie (A Study of the Constrictive Consonant Plus Vowel Sequences in French, Using X-Ray Filming and Oscillography). Publication B-148.

ERIC Educational Resources Information Center

Rochette, Claude; Simard, Claude

A study of the phonetic combination of a constrictive consonant (specifically, [f], [v], and [r]) and a vowel in French using x-ray and oscillograph technology focused on the speed and process of articulation between the consonant and the vowel. The study considered aperture size, nasality, labiality, and accent. Articulation of a total of 407…

Cardiac remodeling in the mouse model of Marfan syndrome develops into two distinctive phenotypes

PubMed Central

Tae, Hyun-Jin; Marshall, Shannon; Krawczyk, Melissa; Talan, Mark

2015-01-01

Marfan syndrome (MFS) is a systemic disorder of connective tissue caused by mutations in fibrillin-1. Cardiac dysfunction in MFS has not been characterized halting the development of therapies of cardiac complication in MFS. We aimed to study the age-dependent cardiac remodeling in the mouse model of MFS FbnC1039G+/− mouse [Marfan heterozygous (HT) mouse] and its association with valvular regurgitation. Marfan HT mice of 2–4 mo demonstrated a mild hypertrophic cardiac remodeling with predominant decline of diastolic function and increased transforming growth factor-β canonical (p-SMAD2/3) and noncanonical (p-ERK1/2 and p-p38 MAPK) signaling and upregulation of hypertrophic markers natriuretic peptides atrium natriuretic peptide and brain natriuretic peptide. Among older HT mice (6–14 mo), cardiac remodeling was associated with two distinct phenotypes, manifesting either dilated or constricted left ventricular chamber. Dilatation of left ventricular chamber was accompanied by biochemical evidence of greater mechanical stress, including elevated ERK1/2 and p38 MAPK phosphorylation and higher brain natriuretic peptide expression. The aortic valve regurgitation was registered in 20% of the constricted group and 60% of the dilated group, whereas mitral insufficiency was observed in 40% of the constricted group and 100% of the dilated group. Cardiac dysfunction was not associated with the increase of interstitial fibrosis and nonmyocyte proliferation. In the mouse model fibrillin-1, haploinsufficiency results in the early onset of nonfibrotic hypertrophic cardiac remodeling and dysfunction, independently from valvular abnormalities. MFS heart is vulnerable to stress-induced cardiac dilatation in the face of valvular regurgitation, and stress-activated MAPK signals represent a potential target for cardiac management in MFS. PMID:26566724

Cardiac remodeling in the mouse model of Marfan syndrome develops into two distinctive phenotypes.

PubMed

Tae, Hyun-Jin; Petrashevskaya, Natalia; Marshall, Shannon; Krawczyk, Melissa; Talan, Mark

2016-01-15

Marfan syndrome (MFS) is a systemic disorder of connective tissue caused by mutations in fibrillin-1. Cardiac dysfunction in MFS has not been characterized halting the development of therapies of cardiac complication in MFS. We aimed to study the age-dependent cardiac remodeling in the mouse model of MFS FbnC1039G+/- mouse [Marfan heterozygous (HT) mouse] and its association with valvular regurgitation. Marfan HT mice of 2-4 mo demonstrated a mild hypertrophic cardiac remodeling with predominant decline of diastolic function and increased transforming growth factor-β canonical (p-SMAD2/3) and noncanonical (p-ERK1/2 and p-p38 MAPK) signaling and upregulation of hypertrophic markers natriuretic peptides atrium natriuretic peptide and brain natriuretic peptide. Among older HT mice (6-14 mo), cardiac remodeling was associated with two distinct phenotypes, manifesting either dilated or constricted left ventricular chamber. Dilatation of left ventricular chamber was accompanied by biochemical evidence of greater mechanical stress, including elevated ERK1/2 and p38 MAPK phosphorylation and higher brain natriuretic peptide expression. The aortic valve regurgitation was registered in 20% of the constricted group and 60% of the dilated group, whereas mitral insufficiency was observed in 40% of the constricted group and 100% of the dilated group. Cardiac dysfunction was not associated with the increase of interstitial fibrosis and nonmyocyte proliferation. In the mouse model fibrillin-1, haploinsufficiency results in the early onset of nonfibrotic hypertrophic cardiac remodeling and dysfunction, independently from valvular abnormalities. MFS heart is vulnerable to stress-induced cardiac dilatation in the face of valvular regurgitation, and stress-activated MAPK signals represent a potential target for cardiac management in MFS.

Ring-diameter Ratios for Multi-ring Basins Average 2.0(0.5)D

NASA Technical Reports Server (NTRS)

Pike, R. J.; Spudis, P. D.

1985-01-01

The spacing of the concentric rings of planetary impact basins was studied. It is shown that a radial increment of x (sup 0.5) D, where x is about 2.0 and D = ring diameter, separates both (1) adjacent least-squares groups of rings and arcs of multi-ring basins on Mars, Mercury, and the Moon; and (2) adjacent rings of individual basins on the three planets. Statistics for ratios of ring diameters are presented, the first and most-applied parameter of ring spacing. It is found that ratios excluding rings flanking the main ring also have a mean spacing increment of about 2.0. Ratios including such rings, as for the least-squares groups, and (1) above, have a larger increment, averaging 2.1. The F-test indicates, that these spacings of basin ring locations, and mode of ring formation are controlled by the mechanics of the impact event itself, rather than by crustal properties.

Clinical features and teratogenic mechanisms of congenital absence of digits.

PubMed

Ogino, Toshihiko

2007-08-01

To have a better understanding of classification of congenital hand anomalies, clinical features and teratogenic mechanisms of congenital absence of digits including ulnar and radial deficiencies, cleft hand, symbrachydactyly and constriction band were reviewed. There seemed to be four different teratogenic mechanisms of congenital absence of digits. Ulnar and radial deficiencies have the same clinical features and the cause of these deficiencies is closely related to a deficit of mesenchymal cells in the limb-bud due to impairment before the formation of the limb-bud. Cleft hand, central polydactyly and osseous syndactyly were induced by the same treatment at the same developmental stage in rats. Roentgenograms of the clinical cases and skeletal changes of the anomalies in rats appear to demonstrate that cleft hand formation proceeds from osseous syndactylies and central polydactylies. The teratogenic mechanism of a cleft hand seemed to be failure of induction of digital rays in the hand plate. The sequence of anomalies from brachysyndactyly, or the atypical cleft hand, to the congenital amputation, can be regarded as equivalent to the category of transverse deficiency that is bony dysplasia of the hand. Congenital constriction ring syndrome appears after the formation of the digital rays.

Jupiter's 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 (km) per picture element (pixel) along the rings; however, 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 2,300,000 kilometers (km) away. The arc on the far right of the image is produced by sunlight 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, which lies exterior to 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 far left side of the figure. 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.

A faint mist of particles can be seen above and below the main rings; this vertically extended, toroidal 'halo' is unusual in planetary rings, and is probably caused by electromagnetic forces which can push small grains out of the ring plane. Halo material is present across this entire image, implying that it reaches more than 27,000 km above the ring plane. Because of shadowing, the halo is not visible close to Jupiter in the lower right part of the mosaic. In order to accentuate faint features in the image, different brightnesses are shown through color, with the brightest

Ex vivo investigation on the postoperative integrity of the apical constriction after the sole use of electronic working length determination.

PubMed

Wolgin, Michael; Grundmann, Markus J; Tchorz, Jörg P; Frank, Wilhelm; Kielbassa, Andrej M

2017-09-01

The present study investigated the accuracy of root canal preparation with regard to the integrity of the apical constriction (AC) using two different working length determination approaches: (1) the electronic method of working length determination (EWLD), and (2) the radiologic "gold standard" method (GS). Simulation models were constructed by arranging extracted human teeth by means of silicon bolstered gingiva masks, along with a conductive medium (alginate). Electronic working length determination (group 1; EWLD) and radiologic plus initial electronic working length determination for posterior comparability (group 2; GS) preceded manual root canal preparation of teeth in both groups. Master cones were inserted according to working lengths obtained from the group specific method. Subsequently, root apices (n=36) were longitudinally sectioned using a diamond-coated bur. The distance between the achieved apical endpoint of the endodontic preparation and the apical constriction (AC) was measured using digital photography. Then, distances between radiologically identified apical endpoints and AC (GS-AC) were compared with the corresponding distances EWLD-AC. Moreover, the postoperative status of the AC was examined with regard to both preparation approaches. Differences between distances GS-AC and EWLD-AC were not statistically significant (p >0.401) (Mann-Whitney-U). Among EWLD samples, 83% of the master cones exhibiting tugback at final insertion terminated close to the apical constriction (±0.5 mm), and no impairment of the minor diameter's integrity was observed. The sole use of EWLD allowed for a high accuracy of measurements and granted precise preparation of the apical regions. Copyright © 2017 Elsevier Ltd. All rights reserved.

The effect of the degree of left renal vein constriction on the development of adolescent varicocele in Sprague-Dawley rats.

PubMed

Yao, Bing; Zhou, Wen-Liang; Han, Da-Yu; Ouyang, Bin; Chen, Xu; Chen, Sheng-Fu; Deng, Chun-Hua; Sun, Xiang-Zhou

2016-01-01

Experimental models have allowed inquiry into the pathophysiology of varicocele (VC) beyond that possible with human patients. A randomized controlled study in rats was designed to clarify the influence of the degree of left renal vein constriction on the development of adolescent VC. Fifty adolescent male Sprague-Dawley rats (Rattus norvegicus) were randomly assigned to five groups of 10: the experimental groups (I-IV) underwent partial ligation of left renal veins with 0.5-, 0.6-, 0.7-, and 0.8-mm diameter needles, respectively. The control group (V) underwent a sham operation. The diameter of the left spermatic vein (LSV) was measured at baseline and 30 days postoperatively. In addition, the lesion of the left kidney was examined with the naked eye and assessed by Masson's trichrome staining. VC was successfully induced in 2 (20%), 4 (40%), 7 (70%), and 10 (100%) rats in groups I-IV, respectively. The other rats failed to develop VCs primarily due to left renal atrophy. No VC was observed in group V. The postsurgical LSV diameters in VC rats in groups III and IV were 1.54 ± 0.16 and 1.49 ± 0.13 mm, respectively (P > 0.05), and their increments were 1.36 ± 0.10 and 1.31 ± 0.10 mm, respectively (P > 0.05). These results suggest that suitable constriction of the left renal vein is critical for adolescent VC development. In addition, the 0.8-mm diameter needle may be more suitable for inducing left renal vein constriction in adolescent rat models.

Possible association between phantom vibration syndrome and occupational burnout.

PubMed

Chen, Chao-Pen; Wu, Chi-Cheng; Chang, Li-Ren; Lin, Yu-Hsuan

2014-01-01

Phantom vibration syndrome (PVS) and phantom ringing syndrome (PRS) occur in many cell phone users. Previous studies have indicated an association between PVS/PRS and job stress. The aim of this study was to determine if PVS/PRS were also associated with occupational burnout. This was a cross-sectional study of 384 employees of a high-tech company in northern Taiwan. They all completed a phantom vibration and ringing questionnaire, the Hospital Anxiety and Depression Scale, and the Chinese version of the Occupational Burnout Inventory. Significantly more women and people with at least a college education were in the population with PRS and PVS, respectively. Anxiety and depression had no associations with PVS/PRS. Higher scores for personal fatigue, job fatigue, and service target fatigue had an independent impact on the presence of PVS, but only a higher score for service target fatigue had an independent impact on the presence of PRS. The independent association between work-related burnout and PVS/PRS suggests that PVS/PRS may be a harbinger of mental stress or a component of the clinical burnout syndrome, and may even be a more convenient and accurate predictor of occupational burnout.

Saturn Ring

NASA Image and Video Library

2007-12-12

Like Earth, Saturn has an invisible ring of energetic ions trapped in its magnetic field. This feature is known as a "ring current." This ring current has been imaged with a special camera on Cassini sensitive to energetic neutral atoms. This is a false color map of the intensity of the energetic neutral atoms emitted from the ring current through a processed called charged exchange. In this process a trapped energetic ion steals and electron from cold gas atoms and becomes neutral and escapes the magnetic field. The Cassini Magnetospheric Imaging Instrument's ion and neutral camera records the intensity of the escaping particles, which provides a map of the ring current. In this image, the colors represent the intensity of the neutral emission, which is a reflection of the trapped ions. This "ring" is much farther from Saturn (roughly five times farther) than Saturn's famous icy rings. Red in the image represents the higher intensity of the particles, while blue is less intense. Saturn's ring current had not been mapped before on a global scale, only "snippets" or areas were mapped previously but not in this detail. This instrument allows scientists to produce movies (see PIA10083) that show how this ring changes over time. These movies reveal a dynamic system, which is usually not as uniform as depicted in this image. The ring current is doughnut shaped but in some instances it appears as if someone took a bite out of it. This image was obtained on March 19, 2007, at a latitude of about 54.5 degrees and radial distance 1.5 million kilometres (920,000 miles). Saturn is at the center, and the dotted circles represent the orbits of the moon's Rhea and Titan. The Z axis points parallel to Saturn's spin axis, the X axis points roughly sunward in the sun-spin axis plane, and the Y axis completes the system, pointing roughly toward dusk. The ion and neutral camera's field of view is marked by the white line and accounts for the cut-off of the image on the left. The

Jupiter Ring

NASA Image and Video Library

2000-03-23

First evidence of a ring around the planet Jupiter is seen in this photograph taken by Voyager 1 on March 4, 1979. The multiple exposure of the extremely thin faint ring appears as a broad light band crossing the center of the picture. The edge of the ring is 1,212,000 km from the spacecraft and 57,000 km from the visible cloud deck of Jupiter. The background stars look like broken hair pins because of spacecraft motion during the 11 minute 12 second exposure. The wavy motion of the star trails is due to the ultra-slow natural oscillation of the spacecraft (with a period of 78 seconds). The black dots are geometric calibration points in the camera. The ring thickness is estimated to be 30 km or less. The photograph was part of a sequence planned to search for such rings in Jupiter's equatorial plane. The ring has been invisible from Earth because of its thinness and its transparency when viewed at any angle except straight on. JPL manages and controls the Voyager Project for NASA's Office of Space Science. http://photojournal.jpl.nasa.gov/catalog/PIA02251

[Analysis of genetics mechanism for the phenotypic diversity in a patient carrying a rare ring chromosome 9].

PubMed

Qin, Shengfang; Wang, Xueyan; Li, Yunxing; Wei, Ping; Chen, Chun; Zeng, Lan

2016-02-01

To explore the genetics mechanism for the phenotypic variability in a patient carrying a rare ring chromosome 9. The karyotype of the patient was analyzed with cytogenetics method. Presence of sex chromosome was confirmed with fluorescence in situ hybridization. The SRY gene was subjected to PCR amplification and direct sequencing. Potential deletion and duplication were detected with array-based comparative genomic hybridization (array-CGH). The karyotype of the patient has comprised 6 types of cell lines containing a ring chromosome 9. The SRY gene sequence was normal. By array-CGH, the patient has carried a hemizygous deletion at 9p24.3-p23 (174 201-9 721 761) encompassing 30 genes from Online Mendelian Inheritance in Man. The phenotypic variability of the 9p deletion syndrome in conjunct with ring chromosome 9 may be attributable to multiple factors including loss of chromosomal material, insufficient dosage of genes, instability of ring chromosome, and pattern of inheritance.

Uveitis-Glaucoma-Hyphaema Syndrome. General review.

PubMed

Zemba, Mihail; Camburu, Georgiana

2017-01-01

Uveitis-Glaucoma-Hyphaema Syndrome (UGH syndrome, or "Ellingson" Syndrome) is a rare condition caused by the mechanical trauma of an intraocular lens malpositioned over adjacent structures (iris, ciliary body, iridocorneal angle), leading to a spectrum of iris transillumination defects, microhyphaemas and pigmentary dispersion, concomitant with elevated intraocular pressure (IOP). UGH Syndrome can also be characterized by chronic inflammation, secondary iris neovascularization, cystoid macular edema (CME). The fundamental step in the pathogenesis of UGH syndrome appears to arise from repetitive mechanical iris trauma by a malpositioned or subluxed IOL. These patients have uncomplicated cataract implants and return for episodes of blurry vision weeks to months after surgery. This may be accompanied by pain, photophobia, erythropsia, anterior uveitis, hyphaema along with raised intraocular pressure. A careful history and examination, as well as appropriate investigations can confirm the diagnostic. Treatment options are IOL Explantation exchange, topical and systemic medication, and cyclophotocoagulation, the placement of a Capsular Tension Ring to redistribute zonular tension and Anti-vascular endothelial growth factor (anti-VEGF) Therapy.

Topological ring currents in the "empty" ring of benzo-annelated perylenes.

PubMed

Dickens, Timothy K; Mallion, Roger B

2011-01-27

Cyclic conjugation in benzo-annelated perylenes is examined by means of the topological π-electron ring currents calculated for each of their constituent rings, in a study that is an exact analogy of a recent investigation by Gutman et al. based on energy-effect values for the corresponding rings in each of these structures. "Classical" approaches, such as Kekulé structures, Clar "sextet" formulas, and circuits of conjugation, predict that the central ring in perylene is "empty" and thus contributes negligibly to cyclic conjugation. However, conclusions from the present calculations of topological ring currents agree remarkably with those arising from the earlier study involving energy-effect values in that, contrary to what would be predicted from the classical approaches, rings annelated in an angular fashion relative to the central ring of these perylene structures materially increase the extent of that ring's involvement in cyclic conjugation. It is suggested that such close quantitative agreement between the predictions of these two superficially very different indices (energy effect and topological ring current) might be due to the fact that, ultimately, both depend, albeit in ostensibly quite different ways, only on an adjacency matrix that contains information about the carbon-carbon connectivity of the conjugated system in question.

Nitrile O-ring Cracking: A Case of Vacuum Flange O-ring Failures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dees, Craig

2016-07-01

A review of recent nitrile O-ring failures in ISO-KF vacuum flange connections in glovebox applications is presented. An investigation of a single “isolated” o-ring failure leads to the discovery of cracked nitrile o-rings in a glovebox atmospheric control unit. The initial cause of the o-ring failure is attributed to ozone degradation. However, additional investigation reveals nitrile o-ring cracking on multiple gloveboxes and general purpose piping, roughly 85% of the nitrile o-rings removed for inspection show evidence of visible cracking after being in service for 18 months or less. The results of material testing and ambient air testing is presented, elevatedmore » ozone levels are not found. The contributing factors of o-ring failure, including nitrile air sensitivity, inadequate storage practices, and poor installation techniques, are discussed. A discussion of nitrile o-ring material properties, the benefits and limitations, and alternate materials are discussed. Considerations for o-ring material selection, purchasing, storage, and installation are presented in the context of lessons learned from the nitrile o-ring cracking investigation. This paper can be presented in 20 minutes and does not require special accommodations or special audio visual devices.« less

DC-Powered Jumping Ring

NASA Astrophysics Data System (ADS)

Jeffery, Rondo N.; Amiri, Farhang

2016-02-01

The classroom jumping ring demonstration is nearly always performed using alternating current (AC), in which the ring jumps or flies off the extended iron core when the switch is closed. The ring jumps higher when cooled with liquid nitrogen (LN2). We have performed experiments using DC to power the solenoid and find similarities and significant differences from the AC case. In particular, the ring does not fly off the core but rises a short distance and then falls back. If the ring jumps high enough, the rising and the falling motion of the ring does not follow simple vertical motion of a projectile. This indicates that there are additional forces on the ring in each part of its motion. Four possible stages of the motion of the ring with DC are identified, which result from the ring current changing directions during the jump in response to a changing magnetic flux through the moving ring.

Oxygen Abundances in the Rings of Polar-Ring Galaxies

NASA Astrophysics Data System (ADS)

Radtke, I. R.; Eskridge, P. B.; Pogge, R. W.

2003-05-01

Polar ring galaxies (PRGs) are typically early-type (S0 or E) galaxies surrounded by rings of gas, dust, and stars orbiting nearly perpendicular to the principle plane of the host galaxy (Whitmore et al. 1990 AJ 100 1489). Given that PRGs have two separate, perpendicular axes of rotation, it is clear on dynamical grounds that PRGs are the products of merger events between two galaxies, but are observed in a state where two distinct kinematic and morphological structures are still apparent. As such, they present a unique opportunity to study merger events in systems where the debris is not confused with material from the host. Our understanding of the relative importance of polar ring systems in the overall process of galaxy evolution is confounded by our lack of knowledge regarding the typical lifetimes and evolutionary histories of polar rings. A crucial factor for understanding the formation and evolution of PRGs is information regarding the elemental abundances of the ring material. Polar rings are typically rich in {\\protectH 2} regions. Optical spectroscopy of these {\\protectH 2} regions can tell us their density, temperature, and oxygen abundance. Our earlier work (Eskridge & Pogge 1997 ApJ 486 259) revealed roughly Solar oxygen abundances for {\\protectH 2} regions in the polar ring of NGC 2685. We have extended this project, and now have spectra for six PRGs. Analysis of the data for II Zw 73 and UGC 7576 reveal the polar rings of these galaxies to have {\\protectH 2} region oxygen abundances in the range 0.3 to 0.6 Solar, substantially less than found for NGC 2685. Abundances in this range are much easier to explain with conventional models of chemical enrichment and polar ring formation. We shall present results for our full sample. Taken as a whole, this sample will provide a clear foundation for the typical chemical enrichment patterns in polar rings, and thus provide a clearer understanding of the formation and evolution of these curious objects. We

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

Planetary Rings

NASA Astrophysics Data System (ADS)

Nicholson, P. D.

2001-11-01

A revolution in the studies in planetary rings studies occurred in the period 1977--1981, with the serendipitous discovery of the narrow, dark rings of Uranus, the first Voyager images of the tenuous jovian ring system, and the many spectacular images returned during the twin Voyager flybys of Saturn. In subsequent years, ground-based stellar occultations, HST observations, and the Voyager flybys of Uranus (1986) and Neptune (1989), as well as a handful of Galileo images, provided much additional information. Along with the completely unsuspected wealth of detail these observations revealed came an unwelcome problem: are the rings ancient or are we privileged to live at a special time in history? The answer to this still-vexing question may lie in the complex gravitational interactions recent studies have revealed 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 parent bodies. Perhaps most puzzling is Saturn's multi-stranded, clumpy F ring, which continues to defy a simple explanation 20 years after it was first glimpsed in grainy images taken by Pioneer 11. Voyager and HST images reveal a complex, probably chaotic, dynamical interaction between unseen parent bodies within this ring and its two shepherd satellites, Pandora and Prometheus. The work described here reflects contributions by Joe Burns, Jeff Cuzzi, Luke Dones, Dick French, Peter Goldreich, Colleen McGhee, Carolyn Porco, Mark Showalter, and Bruno Sicardy, as well as those of the author. This research has been supported by NASA's Planetary Geology and Geophysics program and the

Suspended particle transport through constriction channel with Brownian motion

NASA Astrophysics Data System (ADS)

Hanasaki, Itsuo; Walther, Jens H.

2017-08-01

It is well known that translocation events of a polymer or rod through pores or narrower parts of micro- and nanochannels have a stochastic nature due to the Brownian motion. However, it is not clear whether the objects of interest need to have a larger size than the entrance to exhibit the deviation from the dynamics of the surrounding fluid. We show by numerical analysis that the particle injection into the narrower part of the channel is affected by thermal fluctuation, where the particles have spherical symmetry and are smaller than the height of the constriction. The Péclet number (Pe) is the order parameter that governs the phenomena, which clarifies the spatio-temporal significance of Brownian motion compared to hydrodynamics. Furthermore, we find that there exists an optimal condition of Pe to attain the highest flow rate of particles relative to the dispersant fluid flow. Our finding is important in science and technology from nanopore DNA sequencers and lab-on-a-chip devices to filtration by porous materials and chromatography.

Suspended particle transport through constriction channel with Brownian motion.

PubMed

Hanasaki, Itsuo; Walther, Jens H

2017-08-01

It is well known that translocation events of a polymer or rod through pores or narrower parts of micro- and nanochannels have a stochastic nature due to the Brownian motion. However, it is not clear whether the objects of interest need to have a larger size than the entrance to exhibit the deviation from the dynamics of the surrounding fluid. We show by numerical analysis that the particle injection into the narrower part of the channel is affected by thermal fluctuation, where the particles have spherical symmetry and are smaller than the height of the constriction. The Péclet number (Pe) is the order parameter that governs the phenomena, which clarifies the spatio-temporal significance of Brownian motion compared to hydrodynamics. Furthermore, we find that there exists an optimal condition of Pe to attain the highest flow rate of particles relative to the dispersant fluid flow. Our finding is important in science and technology from nanopore DNA sequencers and lab-on-a-chip devices to filtration by porous materials and chromatography.

CYK-4 regulates Rac, but not Rho, during cytokinesis

PubMed Central

Zhuravlev, Yelena; Hirsch, Sophia M.; Jordan, Shawn N.; Dumont, Julien; Shirasu-Hiza, Mimi; Canman, Julie C.

2017-01-01

Cytokinesis is driven by constriction of an actomyosin contractile ring that is controlled by Rho-family small GTPases. Rho, activated by the guanine-nucleotide exchange factor ECT-2, is upstream of both myosin-II activation and diaphanous formin-mediated filamentous actin (f-actin) assembly, which drive ring constriction. The role for Rac and its regulators is more controversial, but, based on the finding that Rac inactivation can rescue cytokinesis failure when the GTPase-activating protein (GAP) CYK-4 is disrupted, Rac activity was proposed to be inhibitory to contractile ring constriction and thus specifically inactivated by CYK-4 at the division plane. An alternative model proposes that Rac inactivation generally rescues cytokinesis failure by reducing cortical tension, thus making it easier for the cell to divide when ring constriction is compromised. In this alternative model, CYK-4 was instead proposed to activate Rho by binding ECT-2. Using a combination of time-lapse in vivo single-cell analysis and Caenorhabditis elegans genetics, our evidence does not support this alternative model. First, we found that Rac disruption does not generally rescue cytokinesis failure: inhibition of Rac specifically rescues cytokinesis failure due to disruption of CYK-4 or ECT-2 but does not rescue cytokinesis failure due to disruption of two other contractile ring components, the Rho effectors diaphanous formin and myosin-II. Second, if CYK-4 regulates cytokinesis through Rho rather than Rac, then CYK-4 inhibition should decrease levels of downstream targets of Rho. Inconsistent with this, we found no change in the levels of f-actin or myosin-II at the division plane when CYK-4 GAP activity was reduced, suggesting that CYK-4 is not upstream of ECT-2/Rho activation. Instead, we found that the rescue of cytokinesis in CYK-4 mutants by Rac inactivation was Cdc42 dependent. Together our data suggest that CYK-4 GAP activity opposes Rac (and perhaps Cdc42) during cytokinesis

The Ring Sculptor

NASA Image and Video Library

2006-09-08

Prometheus zooms across the Cassini spacecraft field of view, attended by faint streamers and deep gores in the F ring. This movie sequence of five images shows the F ring shepherd moon shaping the ring inner edge

Mechanisms of ring chromosome formation, ring instability and clinical consequences.

PubMed

Guilherme, Roberta S; Meloni, Vera F Ayres; Kim, Chong A; Pellegrino, Renata; Takeno, Sylvia S; Spinner, Nancy B; Conlin, Laura K; Christofolini, Denise M; Kulikowski, Leslie D; Melaragno, Maria I

2011-12-21

The breakpoints and mechanisms of ring chromosome formation were studied and mapped in 14 patients. Several techniques were performed such as genome-wide array, MLPA (Multiplex Ligation-Dependent Probe Amplification) and FISH (Fluorescent in situ Hybridization). The ring chromosomes of patients I to XIV were determined to be, respectively: r(3)(p26.1q29), r(4)(p16.3q35.2), r(10)(p15.3q26.2), r(10)(p15.3q26.13), r(13)(p13q31.1), r(13)(p13q34), r(14)(p13q32.33), r(15)(p13q26.2), r(18)(p11.32q22.2), r(18)(p11.32q21.33), r(18)(p11.21q23), r(22)(p13q13.33), r(22)(p13q13.2), and r(22)(p13q13.2). These rings were found to have been formed by different mechanisms, such as: breaks in both chromosome arms followed by end-to-end reunion (patients IV, VIII, IX, XI, XIII and XIV); a break in one chromosome arm followed by fusion with the subtelomeric region of the other (patients I and II); a break in one chromosome arm followed by fusion with the opposite telomeric region (patients III and X); fusion of two subtelomeric regions (patient VII); and telomere-telomere fusion (patient XII). Thus, the r(14) and one r(22) can be considered complete rings, since there was no loss of relevant genetic material. Two patients (V and VI) with r(13) showed duplication along with terminal deletion of 13q, one of them proved to be inverted, a mechanism known as inv-dup-del. Ring instability was detected by ring loss and secondary aberrations in all but three patients, who presented stable ring chromosomes (II, XIII and XIV). We concluded that the clinical phenotype of patients with ring chromosomes may be related with different factors, including gene haploinsufficiency, gene duplications and ring instability. Epigenetic factors due to the circular architecture of ring chromosomes must also be considered, since even complete ring chromosomes can result in phenotypic alterations, as observed in our patients with complete r(14) and r(22).

Beauty parlor stroke syndrome due to a bone fragment from an osteophyte of the atlas: case report.

PubMed

Kameda, Takuya; Otani, Koji; Tamura, Takamitsu; Konno, Shinichi

2018-04-01

Beauty parlor stroke syndrome (BPSS) is a rare condition characterized by mechanical impingement of a vertebral artery (VA) during neck rotation and/or hyperextension followed by vertebrobasilar insufficiency. However, there have been no reports of BPSS in which the cause of mechanical impingement was identified and no cases for which surgical treatment was reported. The authors report the case of a 56-year-old Japanese man who presented with presyncope that occurred during cervical extension. Given the possibility of vertebrobasilar insufficiency, digital subtraction angiography and CT angiography were performed. These studies revealed that the right VA was hypoplastic and the left VA was dominant. Moreover, in the position of cervical extension, the dominant left VA showed constriction caused by a bone fragment of an osteophyte of the atlas. Removal of the bone fragment was performed. Postoperative left vertebral angiography showed improvement of blood flow in the extended position, and the presyncope completely disappeared. The pathomechanism of this case was a bone fragment compressing the left VA in the C-1 groove during neck extension. In BPSS patients with recurrent transient symptoms, the possibility of this mechanism of VA constriction by a free bone fragment should be considered.

The effect of concentric constriction of the visual field to 10 and 15 degrees on simulated motor vehicle accidents

PubMed Central

Udagawa, Sachiko; Iwase, Aiko; Susuki, Yuto; Kunimatsu-Sanuki, Shiho; Fukuchi, Takeo; Matsumoto, Chota; Ohno, Yuko; Ono, Hiroshi; Sugiyama, Kazuhisa; Araie, Makoto

2018-01-01

Purpose Traffic accidents are associated with the visual function of drivers, as well as many other factors. Driving simulator systems have the advantage of controlling for traffic- and automobile-related conditions, and using pinhole glasses can control the degree of concentric concentration of the visual field. We evaluated the effect of concentric constriction of the visual field on automobile driving, using driving simulator tests. Methods Subjects meeting criteria for normal eyesight were included in the study. Pinhole glasses with variable aperture sizes were adjusted to mimic the conditions of concentric visual field constrictions of 10° and 15°, using a CLOCK CHART®. The test contained 8 scenarios (2 oncoming right-turning cars and 6 jump-out events from the side). Results Eighty-eight subjects were included in the study; 37 (mean age = 52.9±15.8 years) subjects were assigned to the 15° group, and 51 (mean = 48.6±15.5 years) were assigned to the 10° group. For all 8 scenarios, the number of accidents was significantly higher among pinhole wearing subjects. The average number of all types of accidents per person was significantly higher in the pinhole 10° group (4.59±1.81) than the pinhole 15° group (3.68±1.49) (P = 0.032). The number of accidents associated with jump-out scenarios, in which a vehicle approaches from the side on a straight road with a good view, was significantly higher in the pinhole 10° group than in the pinhole 15° group. Conclusions Concentric constriction of the visual field was associated with increased number of traffic accidents. The simulation findings indicated that a visual field of 10° to 15° may be important for avoiding collisions in places where there is a straight road with a good view. PMID:29538425

Saddle-shaped mitral valve annuloplasty rings experience lower forces compared with flat rings.

PubMed

Jensen, Morten O; Jensen, Henrik; Smerup, Morten; Levine, Robert A; Yoganathan, Ajit P; Nygaard, Hans; Hasenkam, J Michael; Nielsen, Sten L

2008-09-30

New insight into the 3D dynamic behavior of the mitral valve has prompted a reevaluation of annuloplasty ring designs. Force balance analysis indicates correlation between annulus forces and stresses in leaflets and chords. Improving this stress distribution can intuitively enhance the durability of mitral valve repair. We tested the hypothesis that saddle-shaped annuloplasty rings have superior uniform systolic force distribution compared with a nonuniform force distribution in flat annuloplasty rings. Sixteen 80-kg pigs had a flat (n=8) or saddle-shaped (n=8) mitral annuloplasty ring implanted. Mitral annulus 3D dynamic geometry was obtained with sonomicrometry before ring insertion. Strain gauges mounted on dedicated D-shaped rigid flat and saddle-shaped annuloplasty rings provided the intraoperative force distribution perpendicular to the annular plane. Average systolic annular height to commissural width ratio before ring implantation was 14.0%+/-1.6%. After flat and saddle shaped ring implantation, the annulus was fixed in the diastolic (9.0%+/-1.0%) and systolic (14.3%+/-1.3%) configuration, respectively (P<0.01). Force accumulation was seen from the anterior (0.72N+/-0.14N) and commissural annular segments (average 1.38N+/-0.27N) of the flat rings. In these segments, the difference between the 2 types of rings was statistically significant (P<0.05). The saddle-shaped annuloplasty rings did not experience forces statistically significantly larger than zero in any annular segments. Saddle-shaped annuloplasty rings provide superior uniform annular force distribution compared to flat rings and appear to represent a configuration that minimizes out-of-plane forces that could potentially be transmitted to leaflets and chords. This may have important implications for annuloplasty ring selections.

So Long, C Ring

NASA Image and Video Library

2017-11-13

Saturn's C ring is home to a surprisingly rich array of structures and textures. Much of the structure seen in the outer portions of Saturn's rings is the result of gravitational perturbations on ring particles by moons of Saturn. Such interactions are called resonances. However, scientists are not clear as to the origin of the structures seen in this image which has captured an inner ring region sparsely populated with particles, making interactions between ring particles rare, and with few satellite resonances. In this image, a bright and narrow ringlet located toward the outer edge of the C ring is flanked by two broader features called plateaus, each about 100 miles (160 kilometers) wide. Plateaus are unique to the C ring. Cassini data indicates that the plateaus do not necessarily contain more ring material than the C ring at large, but the ring particles in the plateaus may be smaller, enhancing their brightness. This view looks toward the sunlit side of the rings from about 53 degrees above the ring plane. The image was taken in green light with the Cassini spacecraft narrow-angle camera on Aug. 14, 2017. The view was acquired at a distance of approximately 117,000 miles (189,000 kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 74 degrees. Image scale is 3,000 feet (1 kilometer) per pixel. The Cassini spacecraft ended its mission on Sept. 15, 2017. https://photojournal.jpl.nasa.gov/catalog/PIA21356

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ledee, Dolena; Smith, Lincoln; Bruce, Margaret

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

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

DOE PAGES

Ledee, Dolena; Smith, Lincoln; Bruce, Margaret; ...

2015-08-12

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

Ring faults and ring dikes around the Orientale basin on the Moon.

PubMed

Andrews-Hanna, Jeffrey C; Head, James W; Johnson, Brandon; Keane, James T; Kiefer, Walter S; McGovern, Patrick J; Neumann, Gregory A; Wieczorek, Mark A; Zuber, Maria T

2018-08-01

The Orientale basin is the youngest and best-preserved multiring impact basin on the Moon, having experienced only modest modification by subsequent impacts and volcanism. Orientale is often treated as the type example of a multiring basin, with three prominent rings outside of the inner depression: the Inner Rook Montes, the Outer Rook Montes, and the Cordillera. Here we use gravity data from NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission to reveal the subsurface structure of Orientale and its ring system. Gradients of the gravity data reveal a continuous ring dike intruded into the Outer Rook along the plane of the fault associated with the ring scarp. The volume of this ring dike is ~18 times greater than the volume of all extrusive mare deposits associated with the basin. The gravity gradient signature of the Cordillera ring indicates an offset along the fault across a shallow density interface, interpreted to be the base of the low-density ejecta blanket. Both gravity gradients and crustal thickness models indicate that the edge of the central cavity is shifted inward relative to the equivalent Inner Rook ring at the surface. Models of the deep basin structure show inflections along the crust-mantle interface at both the Outer Rook and Cordillera rings, indicating that the basin ring faults extend from the surface to at least the base of the crust. Fault dips range from 13-22° for the Cordillera fault in the northeastern quadrant, to 90° for the Outer Rook in the northwestern quadrant. The fault dips for both outer rings are lowest in the northeast, possibly due to the effects of either the direction of projectile motion or regional gradients in pre-impact crustal thickness. Similar ring dikes and ring faults are observed around the majority of lunar basins.

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 ...

Stable forming conditions and geometrical expansion of L-shape rings in ring rolling process

NASA Astrophysics Data System (ADS)

Quagliato, Luca; Berti, Guido A.; Kim, Dongwook; Kim, Naksoo

2018-05-01

Based on previous research results concerning the radial-axial ring rolling process of flat rings, this paper details an innovative approach for the determination of the stable forming conditions to successfully simulate the radial ring rolling process of L-shape profiled rings. In addition to that, an analytical model for the estimation of the geometrical expansion of L-shape rings from its initial flat ring preform is proposed and validated by comparing its results with those of numerical simulations. By utilizing the proposed approach, steady forming conditions could be achieved, granting a uniform expansion of the ring throughout the process for all of the six tested cases of rings having the final outer diameter of the flange ranging from 545mm and 1440mm. The validation of the proposed approach allowed concluding that the geometrical expansion of the ring, as estimated by the proposed analytical model, is in good agreement with the results of the numerical simulation, with a maximum error of 2.18%, in the estimation of the ring wall diameter, 1.42% of the ring flange diameter and 1.87% for the estimation of the inner diameter of the ring, respectively.

Saturn’s Ring Rain: Initial Estimates of Ring Mass Loss Rates

NASA Astrophysics Data System (ADS)

Moore, Luke; O'Donoghue, J.; Mueller-Wodarg, I.; Mendillo, M.

2013-10-01

We estimate rates of mass loss from Saturn’s rings based on ionospheric model reproductions of derived H3+ column densities. On 17 April 2011 over two hours of near-infrared spectral data were obtained of Saturn using the Near InfraRed Spectrograph (NIRSPEC) instrument on the 10-m Keck II telescope. The intensity of two bright H3+ rotational-vibrational emission lines was visible from nearly pole to pole, allowing low-latitude ionospheric emissions to be studied for the first time, and revealing significant latitudinal structure, with local extrema in one hemisphere being mirrored at magnetically conjugate latitudes in the opposite hemisphere. Even more striking, those minima and maxima mapped to latitudes of increased or increased density in Saturn’s rings, implying a direct ring-atmosphere connection in which charged water group particles from the rings are guided by magnetic field lines as they “rain” down upon the atmosphere. Water products act to quench the local ionosphere, and therefore modify the observed H3+ densities. Using the Saturn Thermosphere Ionosphere Model (STIM), a 3-D model of Saturn’s upper atmosphere, we derive the rates of water influx required from the rings in order to reproduce the observed H3+ column densities. As a unique pair of conjugate latitudes map to a specific radial distance in the ring plane, the derived water influxes can equivalently be described as rates of ring mass erosion as a function of radial distance in the ring plane, and therefore also allow for an improved estimate of the lifetime of Saturn’s rings.

Ring chromosome 10: report on two patients and review of the literature.

PubMed

Guilherme, Roberta Santos; Kim, Chong Ae; Alonso, Luis Garcia; Honjo, Rachel S; Meloni, Vera Ayres; Christofolini, Denise Maria; Kulikowski, Leslie Domenici; Melaragno, Maria Isabel

2013-02-01

Ring chromosome 10--r(10)--is a rare disorder, with 14 cases reported in the literature, but only two with breakpoint determination by high-resolution techniques. We report here on two patients presenting a ring chromosome 10, studied by G-banding, fluorescent in situ hybridization (FISH), multiplex ligation-dependent probe amplification (MLPA) and SNP-array techniques, in order to investigate ring instability and determine breakpoints. Patient 1 showed a r(10)(p15.3q26.2) with a 7.9 Mb deletion in 10q26.2-q26.2, while patient 2 showed a r(10)(p15.3q26.13) with a 1.0 Mb deletion in 10p15.3 and a 8.8 Mb deletion in 10q26.13-q26.3, both unstable. While patient 1 presented with clinical features usually found in patients with r(10) and terminal 10q deletion, patient 2 presented characteristics so far not described in other patients with r(10), such as Dandy-Walker variant, osteopenia, semi-flexed legs, and dermal pigmentation regions. Our data and the data from literature show that there are no specific clinical findings to define a r(10) syndrome.

The Enceladus Ring

NASA Technical Reports Server (NTRS)

2006-01-01

[figure removed for brevity, see original site] The Enceladus Ring (labeled)

This excellent view of the faint E ring -- a ring feature now known to be created by Enceladus -- also shows two of Saturn's small moons that orbit within the ring, among a field of stars in the background.

The E ring extends from three to eight Saturn radii -- about 180,000 kilometers (118,000 miles) to 482,000 kilometers (300,000 miles). Its full extent is not visible in this view.

Calypso (22 kilometers, or 14 miles across) and Helene (32 kilometers, or 20 miles across) orbit within the E ring's expanse. Helene skirts the outer parts of the E ring, but here it is projected in front of a region deeper within the ring.

Calypso and Helene are trojan satellites, or moons that orbit 60 degrees in front or behind a larger moon. Calypso is a Tethys trojan and Helene is a trojan of Dione.

An interesting feature of note in this image is the double-banded appearance of the E-ring, which is created because the ring is somewhat fainter in the ringplane than it is 500-1,000 kilometers (300-600 miles) above and below the ringplane. This appearance implies that the particles in this part of the ring have nonzero inclinations (a similar affect is seen in Jupiter's gossamer ring). An object with a nonzero inclination does not orbit exactly at Saturn's ringplane. Instead, its orbit takes it above and below the ringplane. Scientists are not entirely sure why the particles should have such inclinations, but they are fairly certain that the reason involves Enceladus.

One possible explanation is that all the E ring particles come from the plume of icy material that is shooting due south out of the moon's pole. This means all of the particles are created with a certain velocity out of the ringplane, and then they orbit above and below that plane.

Another possible explanation is that Enceladus produces particles with a range of speeds, but the moon gravitationally

PREFACE: Special section on vortex rings Special section on vortex rings

NASA Astrophysics Data System (ADS)

Fukumoto, Yasuhide

2009-10-01

This special section of Fluid Dynamics Research includes five articles on vortex rings in both classical and quantum fluids. The leading scientists of the field describe the trends in and the state-of-the-art development of experiments, theories and numerical simulations of vortex rings. The year 2008 was the 150th anniversary of 'vortex motion' since Hermann von Helmholtz opened up this field. In 1858, Helmholtz published a paper in Crelle's Journal which put forward the concept of 'vorticity' and made the first analysis of vortex motion. Fluid mechanics before that was limited to irrotational motion. In the absence of vorticity, the motion of an incompressible homogeneous fluid is virtually equivalent to a rigid-body motion in the sense that the fluid motion is determined once the boundary configuration is specified. Helmholtz proved, among other things, that, without viscosity, a vortex line is frozen into the fluid. This Helmholtz's law immediately implies the preservation of knots and links of vortex lines and its implication is enormous. One of the major trends of fluid mechanics since the latter half of the 20th century is to clarify the topological meaning of Helmholtz's law and to exploit it to develop theoretical and numerical methods to find the solutions of the Euler equations and to develop experimental techniques to gain an insight into fluid motion. Vortex rings are prominent coherent structures in a variety of fluid motions from the microscopic scale, through human and mesoscale to astrophysical scales, and have attracted people's interest. The late professor Philip G Saffman (1981) emphasized the significance of studies on vortex rings. One particular motion exemplifies the whole range of problems of vortex motion and is also a commonly known phenomenon, namely the vortex ring or smoke ring. Vortex rings are easily produced by dropping drops of one liquid into another, or by puffing fluid out of a hole, or by exhaling smoke if one has the skill

Surface roughness of Saturn's rings and ring particles inferred from thermal phase curves

NASA Astrophysics Data System (ADS)

Morishima, Ryuji; Turner, Neal J.; Spilker, Linda

2017-10-01

We analyze thermal phase curves of all the main rings of Saturn (the A, B, C rings, and the Cassini division) measured by both the far-IR and mid-IR detectors of the Cassini Composite InfraRed Spectrometer (CIRS). All the rings show temperature increases toward zero phase angle, known as an opposition effect or thermal beaming. For the C ring and Cassini division, which have low optical depths, intra-particle shadowing is considered the dominant mechanism causing the effect. On the other hand, the phase curves of the optically thick B and A rings steepen significantly with decreasing absolute solar elevation angle from 21° to 14°, suggesting inter-particle shadowing plays an important role in these rings. We employ an analytic roughness model to estimate the degrees of surface roughness of the rings or ring particles. For optically thin rings, an isolated particle covered by spherical segment craters is employed while for the thick rings we approximate a packed particle layer as a slab covered by craters. The particles in the thin rings are found to have generally rough surfaces, except in the middle C ring. Across the C ring, the optical depth correlates with the degree of surface roughness. This may indicate that surface roughness comes mainly from particle clumping, while individual particles have rather smooth surfaces. For the optically thick rings, the surface roughness of the particle layer is found to be moderate. The modeled phase curves of optically thick rings are shallow if the phase angle change is primarily due to change of observer azimuthal angle. On the other hand, the phase curves are steep if the phase angle change is due to change of observer elevation angle, as inter-particle shadows become visible at higher observer elevation. In addition, the area of shadowed facets increases with decreasing solar elevation angle. These combined effects explain the large seasonal change of the phase curve steepness observed for the thick rings. The degrees

Surface roughness of Saturn's rings and ring particles inferred from thermal phase curves

NASA Astrophysics Data System (ADS)

Morishima, Ryuji; Turner, Neal; Spilker, Linda

2017-10-01

We analyze thermal phase curves of all the main rings of Saturn (the A, B, C rings, and the Cassini division) measured by both the far-IR and mid-IR detectors of the Cassini Composite InfraRed Spectrometer (CIRS). All the rings show temperature increases toward zero phase angle, known as an opposition effect or thermal beaming. For the C ring and Cassini division, which have low optical depths, intra-particle shadowing is considered the dominant mechanism causing the effect. On the other hand, the phase curves of the optically thick B and A rings steepen significantly with decreasing absolute solar elevation angle from 21° to 14°, suggesting inter-particle shadowing plays an important role in these rings. We employ an analytic roughness model to estimate the degrees of surface roughness of the rings or ring particles. For optically thin rings, an isolated particle covered by spherical segment craters is employed while for the thick rings we approximate a packed particle layer as a slab covered by craters. The particles in the thin rings are found to have generally rough surfaces, except in the middle C ring. Across the C ring, the optical depth correlates with the degree of surface roughness. This may indicate that surface roughness comes mainly from particle clumping, while individual particles have rather smooth surfaces. For the optically thick rings, the surface roughness of the particle layer is found to be moderate. The modeled phase curves of optically thick rings are shallow if the phase angle change is primarily due to change of observer azimuthal angle. On the other hand, the phase curves are steep if the phase angle change is due to change of observer elevation angle, as inter-particle shadows become visible at higher observer elevation. In addition, the area of shadowed facets increases with decreasing solar elevation angle. These combined effects explain the large seasonal change of the phase curve steepness observed for the thick rings. The degrees

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.

Dusty D Ring

NASA Image and Video Library

2014-02-24

Saturn D ring is easy to overlook since it trapped between the brighter C ring and the planet itself. In this view from NASA Cassini spacecraft, all that can be seen of the D ring is the faint and narrow arc as it stretches from top right of the ima

Ring World

NASA Image and Video Library

2007-03-01

Our robotic emissary, flying high above Saturn, captured this view of an alien copper-colored ring world. The overexposed planet has deliberately been removed to show the unlit rings alone, seen from an elevation of 60 degrees

Possible association between phantom vibration syndrome and occupational burnout

PubMed Central

Chen, Chao-Pen; Wu, Chi-Cheng; Chang, Li-Ren; Lin, Yu-Hsuan

2014-01-01

Background Phantom vibration syndrome (PVS) and phantom ringing syndrome (PRS) occur in many cell phone users. Previous studies have indicated an association between PVS/PRS and job stress. The aim of this study was to determine if PVS/PRS were also associated with occupational burnout. Methods This was a cross-sectional study of 384 employees of a high-tech company in northern Taiwan. They all completed a phantom vibration and ringing questionnaire, the Hospital Anxiety and Depression Scale, and the Chinese version of the Occupational Burnout Inventory. Results Significantly more women and people with at least a college education were in the population with PRS and PVS, respectively. Anxiety and depression had no associations with PVS/PRS. Higher scores for personal fatigue, job fatigue, and service target fatigue had an independent impact on the presence of PVS, but only a higher score for service target fatigue had an independent impact on the presence of PRS. Conclusion The independent association between work-related burnout and PVS/PRS suggests that PVS/PRS may be a harbinger of mental stress or a component of the clinical burnout syndrome, and may even be a more convenient and accurate predictor of occupational burnout. PMID:25750984

Usher's syndrome--case report.

PubMed

Kwiecień, Sława; Sulak, Robert; Szaflik, Jerzy

2008-01-01

The aim of this study is to present a case of coincidence of sensorineural hearing loss with chronic recurrent bilateral cystoid macular oedema in a 32-year-old woman, who was admitted to the clinic for deterioration of visual acuity of four months' duration. The patient gave a history of hearing loss for 29 years. Visual field examination disclosed peripheral ring scotoma. Electrophysiological examination was performed: pattern visual evoked response was within normal limits and electroretinogram displayed diminished both photopic and scotopic response. As ophthalmoscopy demonstrated no pigment in the fundus of the eye, the findings were consisted with diagnosis of retinitis pigmentosis sine pigmento. The presence of loss of hearing indicated the necessity of performing the genetic examination for Usher's syndrome. In order to establish a final diagnosis of Usher's syndrome genetic examination must be performed, but family history is relevant. Early investigation for Usher's syndrome in children with sensorineural hearing impairment is of a great significance. The patient may develop symptoms of retinitis pigmentosa in second or even third decade of his life. The necessity of thorough investigation for detecting other systemic abnormalities should be emphasized. There is no effective treatment of this syndrome. A child with Usher's syndrome requires a comprehensive care of different medical specialties. Psychological, educational and sociological attitude is also of a great importance in the child development.

Planetary rings: Structure and history

NASA Astrophysics Data System (ADS)

Esposito, L.

The composition and structure of planetary rings provide the key evidence to understand their origin and evolution. Before the first space observations, we were able to maintain an idealized view of the rings around Saturn, the only known ring system at that time. Rings were then discovered around Jupiter, Uranus and Neptune. Saturn's F ring was discovered by Pioneer 11. Our ideal view of circular, planar, symmetric and unchanging rings was shattered by observations of inclined, eccentric rings, waves and wavy edges, and numerous processes acting at rates that give timescales much younger than the solar system. Moons within and near the rings sculpt them and are the likely progenitors of future rings. The moonlet lifetimes are much less than Saturn's age. The old idea of ancient rings gave rise to youthful rings, that are recently created by erosion and destruction of small nearby moons. Although this explanation may work well for most rings, Saturn's massive ring system provides a problem. It is extremely improbable that Saturn's rings were recently created by the destruction of a moon as large as Mimas, or even by the breakup of a large comet that passed too close to Saturn. The history of Saturn's rings has been a difficult problem, now made even more challenging by the close-up Cassini measurements. Cassini observations show unexpected ring variability in time and space. Time variations are seen in ring edges, in the thinner D and F rings, and in the neutral oxygen cloud, which outweighs the E ring in the same region around Saturn. The rings are inhomogeneous, with structures on all scales, sharp gradients and edges. Compositional gradients are sharper than expected, but nonetheless cross structural boundaries. This is evidence for ballistic transport that has not gone to completion. The autocovariance maximizes in the middle of the A ring, with smaller structure near the main rings' outer edge. Density wave locations have a fresher ice composition. The

Large thoracic tumor without superior vena cava syndrome.

PubMed

Garmpis, Nikolaos; Damaskos, Christos; Patelis, Nikolaos; Dimitroulis, Dimitrios; Spartalis, Eleftherios; Tomos, Ioannis; Garmpi, Anna; Spartalis, Michael; Antoniou, Efstathios A; Kontzoglou, Konstantinos; Tomos, Periklis

2017-04-10

A 62 year-old male with long-standing smoking history presented with hemoptysis. Plain chest x-ray showed abnormal findings proximate to the right pulmonary hilum. Bronchoscopy revealed a fragile exophytic tumor of the right wall of the lower third of the trachea, infiltrating the right main bronchus (75% stenosis) and the right upper lobar bronchus (near total occlusion). Contrast-enhanced chest CT demonstrated a 7.2x4.9 cm tumor contiguous to the above-mentioned structures, mediastinal lymph node pathology, and a vessel coursing inferiorly to the left of the aortic arch and anterior to the left hilum. Despite the tumor constricting the right superior vena cava, no signs of superior vena cava syndrome were present. In this case, the patient does not present with Superior Vena Cava (SVC) syndrome, as expected due to the constriction of the (right) SVC caused by the tumor, since head and neck veins drain through the Persistent Left Superior Vena Cava (PLSVC). PLSVC is the most common thoracic venous anomaly with an incidence of 0.3% to 0.5% of the general population and it is a congenital anomaly caused by the failure of the left anterior cardinal vein to regress and to consequently form the ligament of Marshall during fetal development. It is associated with absence of the left brachiocephalic vein and in 10 to 20% of cases the right SVC is absent. Two potential draining points of the PLSVC have been previously reported. In the majority of cases PLSVC drains directly into the coronary sinus, but less frequently it drains into the left atrium or the left superior pulmonary vein. In cases where the PLSVC drains into the coronary sinus, congenital heart defects are rare. The patient usually remains asymptomatic and PLSVC is an incidental finding during radiographic imaging or medical procedures. When the PLSVC drains into the left atrium or the left superior pulmonary vein, a right-to-left shunt is formed; a condition usually asymptomatic. In some reported cases this

Ring King

NASA Image and Video Library

2014-08-18

Saturn reigns supreme, encircled by its retinue of rings. Although all four giant planets have ring systems, Saturn's is by far the most massive and impressive. Scientists are trying to understand why by studying how the rings have formed and how they have evolved over time. Also seen in this image is Saturn's famous north polar vortex and hexagon. This view looks toward the sunlit side of the rings from about 37 degrees above the ringplane. The image was taken with the Cassini spacecraft wide-angle camera on May 4, 2014 using a spectral filter which preferentially admits wavelengths of near-infrared light centered at 752 nanometers. The view was acquired at a distance of approximately 2 million miles (3 million kilometers) from Saturn. Image scale is 110 miles (180 kilometers) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA18278

Evaluating GPS biologging technology for studying spatial ecology of large constricting snakes

USGS Publications Warehouse

Smith, Brian; Hart, Kristen M.; Mazzotti, Frank J.; Basille, Mathieu; Romagosa, Christina M.

2018-01-01

Background: GPS telemetry has revolutionized the study of animal spatial ecology in the last two decades. Until recently, it has mainly been deployed on large mammals and birds, but the technology is rapidly becoming miniaturized, and applications in diverse taxa are becoming possible. Large constricting snakes are top predators in their ecosystems, and accordingly they are often a management priority, whether their populations are threatened or invasive. Fine-scale GPS tracking datasets could greatly improve our ability to understand and manage these snakes, but the ability of this new technology to deliver high-quality data in this system is unproven. In order to evaluate GPS technology in large constrictors, we GPS-tagged 13 Burmese pythons (Python bivittatus) in Everglades National Park and deployed an additional 7 GPS tags on stationary platforms to evaluate habitat-driven biases in GPS locations. Both python and test platform GPS tags were programmed to attempt a GPS fix every 90 min.Results: While overall fix rates for the tagged pythons were low (18.1%), we were still able to obtain an average of 14.5 locations/animal/week, a large improvement over once-weekly VHF tracking. We found overall accuracy and precision to be very good (mean accuracy = 7.3 m, mean precision = 12.9 m), but a very few imprecise locations were still recorded (0.2% of locations with precision > 1.0 km). We found that dense vegetation did decrease fix rate, but we concluded that the low observed fix rate was also due to python microhabitat selection underground or underwater. Half of our recovered pythons were either missing their tag or the tag had malfunctioned, resulting in no data being recovered.Conclusions: GPS biologging technology is a promising tool for obtaining frequent, accurate, and precise locations of large constricting snakes. We recommend future studies couple GPS telemetry with frequent VHF locations in order to reduce bias and limit the impact of catastrophic

A Pauson-Khand and ring-expansion approach to the aquariane ring system.

PubMed

Thornton, Paul D; Burnell, D Jean

2006-07-20

[Structure: see text] The carbocyclic ring system of the aquariolide diterpenes has been synthesized by two routes involving a diastereoselective Pauson-Khand reaction and subsequent ring expansion. In one route, a tetracyclic enone was elaborated to generate the nine-membered ring by Grob fragmentation. In the second approach, a spirocyclic tricycle underwent a facile anionic oxy-Cope rearrangement to complete the synthesis of the desired ring system.

Update on the efficacy of extracorporeal shockwave treatment for myofascial pain syndrome and fibromyalgia.

PubMed

Ramon, Silvia; Gleitz, Markus; Hernandez, Leonor; Romero, Luis David

2015-12-01

Chronic muscle pain syndrome is one of the main causes of musculoskeletal pathologies requiring treatment. Many terms have been used in the past to describe painful muscular syndromes in the absence of evident local nociception such as myogelosis, muscle hardening, myalgia, muscular rheumatism, fibrositis or myofascial trigger point with or without referred pain. If it persists over six months or more, it often becomes therapy resistant and frequently results in chronic generalized pain, characterized by a high degree of subjective suffering. Myofascial pain syndrome (MPS) is defined as a series of sensory, motor, and autonomic symptoms caused by a stiffness of the muscle, caused by hyperirritable nodules in musculoskeletal fibers, known as myofascial trigger points (MTP), and fascial constrictions. Fibromyalgia (FM) is a chronic condition that involves both central and peripheral sensitization and for which no curative treatment is available at the present time. Fibromyalgia shares some of the features of MPS, such as hyperirritability. Many treatments options have been described for muscle pain syndrome, with differing evidence of efficacy. Extracorporeal Shockwave Treatment (ESWT) offers a new and promising treatment for muscular disorders. We will review the existing bibliography on the evidence of the efficacy of ESWT for MPS, paying particular attention to MTP (Myofascial Trigger Point) and Fibromyalgia (FM). Copyright © 2015 IJS Publishing Group Limited. Published by Elsevier Ltd. All rights reserved.

O-Ring-Testing Fixture

NASA Technical Reports Server (NTRS)

Turner, James E.; Mccluney, D. Scott

1991-01-01

Fixture tests O-rings for sealing ability under dynamic conditions after extended periods of compression. Hydraulic cylinder moves plug in housing. Taper of 15 degrees on plug and cavity of housing ensures that gap created between O-ring under test and wall of cavity. Secondary O-rings above and below test ring maintain pressure applied to test ring. Evaluates effects of variety of parameters, including temperature, pressure, rate of pressurization, rate and magnitude of radial gap movement, and pretest compression time.

Nardo Ring, Italy

NASA Technical Reports Server (NTRS)

2008-01-01

The Nardo Ring is a striking visual feature from space, and astronauts have photographed it several times. The Ring is a race car test track; it is 12.5 kilometers long and steeply banked to reduce the amount of active steering needed by drivers. The Nardo Ring lies in a remote area on the heel of Italy's 'boot,' 50 kilometers east of the naval port of Taranto. The Ring encompasses a number of active (green) and fallow (brown to dark brown) agricultural fields. In this zone of intensive agriculture, farmers gain access to their fields through the Ring via a series of underpasses. Winding features within the southern section of the Ring appear to be smaller, unused race tracks.

The image covers an area of 18.8 x 16.4 km, was acquired on August 17. 2007, and is located at 49.3 degrees north latitude, 17.8 degrees east longitude.

The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

Prefission Constriction of Golgi Tubular Carriers Driven by Local Lipid Metabolism: A Theoretical Model

PubMed Central

Shemesh, Tom; Luini, Alberto; Malhotra, Vivek; Burger, Koert N. J.; Kozlov, Michael M.

2003-01-01

Membrane transport within mammalian cells is mediated by small vesicular as well as large pleiomorphic transport carriers (TCs). A major step in the formation of TCs is the creation and subsequent narrowing of a membrane neck connecting the emerging carrier with the initial membrane. In the case of small vesicular TCs, neck formation may be directly induced by the coat proteins that cover the emerging vesicle. However, the mechanism underlying the creation and narrowing of a membrane neck in the generation of large TCs remains unknown. We present a theoretical model for neck formation based on the elastic model of membranes. Our calculations suggest a lipid-driven mechanism with a central role for diacylglycerol (DAG). The model is applied to a well-characterized in vitro system that reconstitutes TC formation from the Golgi complex, namely the pearling and fission of Golgi tubules induced by CtBP/BARS, a protein that catalyzes the conversion of lysophosphatidic acid into phosphatidic acid. In view of the importance of a PA-DAG cycle in the formation of Golgi TCs, we assume that the newly formed phosphatidic acid undergoes rapid dephosphorylation into DAG. DAG possesses a unique molecular shape characterized by an extremely large negative spontaneous curvature, and it redistributes rapidly between the membrane monolayers and along the membrane surface. Coupling between local membrane curvature and local lipid composition results, by mutual enhancement, in constrictions of the tubule into membrane necks, and a related inhomogeneous lateral partitioning of DAG. Our theoretical model predicts the exact dimensions of the constrictions observed in the pearling Golgi tubules. Moreover, the model is able to explain membrane neck formation by physiologically relevant mole fractions of DAG. PMID:14645071

[Laser Induced Fluorescence Spectroscopic Analysis of Aromatics from One Ring to Four Rings].

PubMed

Zhang, Peng; Liu, Hai-feng; Yue, Zong-yu; Chen, Bei-ling; Yao, Ming-fa

2015-06-01

In order to distinguish small aromatics preferably, a Nd : YAG Laser was used to supply an excitation laser, which was adjusted to 0.085 J x cm(-2) at 266 nm. Benzene, toluene, naphthalene, phenanthrene, anthracene, pyrene and chrysene were used as the representative of different rings aromatics. The fluorescence emission spectra were researched for each aromatic hydrocarbon and mixtures by Laser induced fluorescence (LIF). Results showed that the rings number determined the fluorescence emission spectra, and the structure with same rings number did not affect the emission fluorescence spectrum ranges. This was due to the fact that the absorption efficiency difference at 266 nm resulted in that the fluorescence intensities of each aromatic hydrocarbon with same rings number were different and the fluorescence intensities difference were more apparently with aromatic ring number increasing. When the absorption efficiency was similar at 266 nm and the concentrations of each aromatic hydrocarbon were same, the fluorescence intensities were increased with aromatic ring number increasing. With aromatic ring number increasing, the fluorescence spectrum and emission peak wavelength were all red-shifted from ultraviolet to visible and the fluorescence spectrum range was also wider as the absorption efficiency was similar. The fluorescence emission spectra from one to four rings could be discriminated in the following wavelengths, 275 to 320 nm, 320 to 375 nm, 375 to 425 nm, 425 to 556 nm, respectively. It can be used for distinguish the type of the polycyclic aromatic hydrocarbons (PAHs) as it exists in single type. As PAHs are usually exist in a variety of different rings number at the same time, the results for each aromatic hydrocarbon may not apply to the aromatic hydrocarbon mixtures. For the aromatic hydrocarbon mixtures, results showed that the one- or two-ring PAHs in mixtures could not be detected by fluorescence as three- or four-ring PAHs existed in mixture

Electrostatic forces in planetary rings

NASA Technical Reports Server (NTRS)

Goertz, C. K.; Shan, Linhua; Havnes, O.

1988-01-01

The average charge on a particle in a particle-plasma cloud, the plasma potential inside the cloud, and the Coulomb force acting on the particle are calculated. The net repulsive electrostatic force on a particle depends on the plasma density, temperature, density of particles, particle size, and the gradient of the particle density. In a uniformly dense ring the electrostatic repulsion is zero. It is also shown that the electrostatic force acts like a pressure force, that even a collisionless ring can be stable against gravitational collapse, and that a finite ring thickness does not necessarily imply a finite velocity dispersion. A simple criterion for the importance of electrostatic forces in planetary rings is derived which involves the calculation of the vertical ring thickness which would result if only electrostatic repulsion were responsible for the finite ring thickness. Electrostatic forces are entirely negligible in the main rings of Saturn and the E and G rings. They may also be negligible in the F ring. However, the Uranian rings and Jupiter's ring seem to be very much influenced by electrostatic repulsion. In fact, electrostatic forces could support a Jovian ring which is an order of magnitude more dense than observed.

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 FISHmore » ordering system, we sublocalized ZNF179 proximally to LLGL which lies on the critical region for SMS. 27 refs., 2 figs.« less

How does the blue-ringed octopus (Hapalochlaena lunulata) flash its blue rings?

PubMed

Mäthger, Lydia M; Bell, George R R; Kuzirian, Alan M; Allen, Justine J; Hanlon, Roger T

2012-11-01

The blue-ringed octopus (Hapalochlaena lunulata), one of the world's most venomous animals, has long captivated and endangered a large audience: children playing at the beach, divers turning over rocks, and biologists researching neurotoxins. These small animals spend much of their time in hiding, showing effective camouflage patterns. When disturbed, the octopus will flash around 60 iridescent blue rings and, when strongly harassed, bite and deliver a neurotoxin that can kill a human. Here, we describe the flashing mechanism and optical properties of these rings. The rings contain physiologically inert multilayer reflectors, arranged to reflect blue-green light in a broad viewing direction. Dark pigmented chromatophores are found beneath and around each ring to enhance contrast. No chromatophores are above the ring; this is unusual for cephalopods, which typically use chromatophores to cover or spectrally modify iridescence. The fast flashes are achieved using muscles under direct neural control. The ring is hidden by contraction of muscles above the iridophores; relaxation of these muscles and contraction of muscles outside the ring expose the iridescence. This mechanism of producing iridescent signals has not previously been reported in cephalopods and we suggest that it is an exceptionally effective way to create a fast and conspicuous warning display.

Efficacy of advice from healthcare professionals to pregnant women on avoiding constrictive clothing around the trunk: a study protocol for a randomised controlled trial.

PubMed

Takehara, Kenji; Kato, Sachiko; Sasaki, Aiko; Jwa, Seung Chik; Kakee, Naoko; Sago, Haruhiko; Noguchi, Yuko; Aoki, Tomoko; Inoue, Eisuke; Nitta, Chieko; Ishii, Yumiko

2015-09-30

As a component of midwife care, eliminating clothing that constricts the trunk has been shown to markedly elevate the uterine fundus, soften the uterus and abdomen, and reduce the abdominal wall tension in women admitted to hospital due to the risk of miscarriage or premature delivery. However, no prospective study has conclusively verified the efficacy of avoiding constrictive clothes around the trunk in pregnant women. We aim to verify the efficacy of instructing pregnant women to wear loose clothing that does not constrict the trunk to reduce the risk of premature birth and improve quality of life (QoL) during pregnancy. We will conduct a randomised controlled trial of pregnant women scheduled to deliver at the National Center for Child Health and Development in Tokyo, Japan. A total of 616 pregnant women, from whom written informed consent will be obtained, will be allocated randomly to an intervention group or a control group. Women in the control group will be provided with anaemia prevention leaflets at 20 weeks' gestation and skin-care leaflets at 30 weeks' gestation. Women in the intervention group will be provided with the same leaflets and will also receive health advice from health professionals to avoid constrictive clothing around the trunk. The primary outcome will be a difference between these groups in the frequency of any one of the following category variables: (1) cervical length <30 mm up to 28 weeks' gestation, (2) hospital admission for threatened premature delivery, or (3) premature delivery. Secondary outcomes will include QoL during pregnancy, maternal state of health, and status of fetal development. The Institutional Review Board and Ethics Committee at the National Center for Child Health and Development, Japan, has approved this study. Our findings will be widely disseminated through conference presentations and peer-reviewed publications. UMIN000016853. Published by the BMJ Publishing Group Limited. For permission to use

Efficacy of advice from healthcare professionals to pregnant women on avoiding constrictive clothing around the trunk: a study protocol for a randomised controlled trial

PubMed Central

Takehara, Kenji; Kato, Sachiko; Sasaki, Aiko; Jwa, Seung Chik; Kakee, Naoko; Sago, Haruhiko; Noguchi, Yuko; Aoki, Tomoko; Inoue, Eisuke; Nitta, Chieko; Ishii, Yumiko

2015-01-01

Introduction As a component of midwife care, eliminating clothing that constricts the trunk has been shown to markedly elevate the uterine fundus, soften the uterus and abdomen, and reduce the abdominal wall tension in women admitted to hospital due to the risk of miscarriage or premature delivery. However, no prospective study has conclusively verified the efficacy of avoiding constrictive clothes around the trunk in pregnant women. We aim to verify the efficacy of instructing pregnant women to wear loose clothing that does not constrict the trunk to reduce the risk of premature birth and improve quality of life (QoL) during pregnancy. Methods and analysis We will conduct a randomised controlled trial of pregnant women scheduled to deliver at the National Center for Child Health and Development in Tokyo, Japan. A total of 616 pregnant women, from whom written informed consent will be obtained, will be allocated randomly to an intervention group or a control group. Women in the control group will be provided with anaemia prevention leaflets at 20 weeks’ gestation and skin-care leaflets at 30 weeks’ gestation. Women in the intervention group will be provided with the same leaflets and will also receive health advice from health professionals to avoid constrictive clothing around the trunk. The primary outcome will be a difference between these groups in the frequency of any one of the following category variables: (1) cervical length <30 mm up to 28 weeks’ gestation, (2) hospital admission for threatened premature delivery, or (3) premature delivery. Secondary outcomes will include QoL during pregnancy, maternal state of health, and status of fetal development. Ethics and dissemination The Institutional Review Board and Ethics Committee at the National Center for Child Health and Development, Japan, has approved this study. Our findings will be widely disseminated through conference presentations and peer-reviewed publications. Trial registration

Chronic Constriction Injury of the Infraorbital Nerve in the Rat using modified syringe needle

PubMed Central

Kernisant, Melanie; Gear, Robert; Jasmin, Luc; Vit, Jean-Philippe; Ohara, Peter T.

2008-01-01

Here we report a method for performing a chronic constriction injury (CCI) of the infraorbital nerve (ION) in the rat as a component of a chronic pain model. The surgical approach to the ION is described together with the use of a modified dental syringe needle that simplifies placing two chromic gut ligatures around the ION. This method makes the surgical procedure easier, the nerve injury more consistent across animals and reduces secondary damage to the ION and surrounding tissue. Pain behavior testing together with immunostaining for markers of nerve injury in the spinal trigeminal nucleus show the suitability of this procedure as a model of orofacial pain. PMID:18501433

The Crossings of Saturn Ring Plane by the Earth in 1995: Ring Thickness

NASA Astrophysics Data System (ADS)

Poulet, François; Sicardy, Bruno; Dumas, Christophe; Jorda, Laurent; Tiphène, Didier

2000-05-01

The crossings of Saturn's ring plane by Earth were observed in the near infrared on May 22 and August 10, 1995, from the 2.2-m telescope of the University of Hawaii, the 2-m telescope at Pic du Midi, France, and with the Adonis adaptive optics camera at the 3.6-m telescope of the European Southern Observatory in Chile. Images from the Hubble Space Telescope, obtained in August 1995, are also reanalyzed. The radial brightness profiles of the rings indicate that the outer and usually faint F ring dominates the edge-on brightness of the system, thus hiding the vertical structure of the main rings within a few hours around the ring plane crossing. The photometric behaviors of the A, B, and C rings and of the Cassini Division are analyzed, using a radiative transfer code which includes the illuminations by the Sun and by the planet. The F ring is modeled as a physically thick ribbon of height H, composed of large particles embedded in dust of fractional optical depth f. The observed profiles, combined with previous results, can be explained if the F ring is both optically thick ( radial optical depth ˜0.20) and physically thick ( H=21±4 km). We suggest that this vertical distribution results from the interactions between ring particles and shepherding satellites and/or from gravitational stirring by large bodies. The dust particles dominate the F ring's photometric behavior even in backscattered light ( f>0.80). Constraints on the particle properties of the other rings are also derived.

Luminescent Rings

NASA Technical Reports Server (NTRS)

2005-01-01

This view shows the unlit face of Saturn's rings, visible via scattered and transmitted light. In these views, dark regions represent gaps and areas of higher particle densities, while brighter regions are filled with less dense concentrations of ring particles.

The dim right side of the image contains nearly the entire C ring. The brighter region in the middle is the inner B ring, while the darkest part represents the dense outer B Ring. The Cassini Division and the innermost part of the A ring are at the upper-left.

Saturn's shadow carves a dark triangle out of the lower right corner of this image.

The image was taken in visible light with the Cassini spacecraft wide-angle camera on June 8, 2005, at a distance of approximately 433,000 kilometers (269,000 miles) from Saturn. The image scale is 22 kilometers (14 miles) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

A Photo-Favorskii Ring Contraction Reaction: The Effect of Ring Size

PubMed Central

Kammath, Viju Balachandran; Šolomek, Tomáš; Ngoy, Bokolombe Pitchou; Heger, Dominik; Klán, Petr; Rubina, Marina; Givens, Richard S.

2012-01-01

The effect of ring size on the photo-Favorskii induced ring-contraction reaction of the hydroxybenzocycloalkanonyl acetate and mesylate esters (7a–d, 8a–c) has provided new insight into the mechanism of the rearrangement. By monotonically decreasing the ring size in these cyclic derivatives, the increasing ring strain imposed on the formation of the elusive bicyclic spirocyclopropanone 20 results in a divergence away from rearrangement and toward solvolysis. Cycloalkanones of seven or eight carbons undergo a highly efficient photo-Favorskii rearrangement with ring contraction paralleling the photochemistry of p-hydroxyphenacyl esters. In contrast, the five-carbon ring does not rearrange but is diverted to the photosolvolysis channel avoiding the increased strain energy that would accompany the formation of the spirobicyclic ketone, the “Favorskii intermediate 20”. The six-carbon analogue demonstrates the bifurcation in reaction channels, yielding a solvent-sensitive mixture of both. Employing a combination of time-resolved absorption measurements, quantum yield determinations, isotopic labeling, and solvent variation studies coupled with theoretical treatment, a more comprehensive mechanistic description of the rearrangement has emerged. PMID:22686289

Iodine I 131 Monoclonal Antibody BC8, Fludarabine Phosphate, Cyclophosphamide, Total-Body Irradiation and Donor Bone Marrow Transplant in Treating Patients With Advanced Acute Myeloid Leukemia, Acute Lymphoblastic Leukemia, or High-Risk Myelodysplastic Syndrome

ClinicalTrials.gov

2018-05-14

Acute Myeloid Leukemia Arising From Previous Myelodysplastic Syndrome; Adult Acute Lymphoblastic Leukemia in Remission; Adult Acute Myeloid Leukemia in Remission; CD45-Positive Neoplastic Cells Present; Chronic Myelomonocytic Leukemia; Previously Treated Myelodysplastic Syndrome; Refractory Anemia With Excess Blasts; Refractory Anemia With Ring Sideroblasts; Refractory Cytopenia With Multilineage Dysplasia; Refractory Cytopenia With Multilineage Dysplasia and Ring Sideroblasts

Earth: A Ringed Planet?

NASA Astrophysics Data System (ADS)

Hancock, L. O.; Povenmire, H.

2010-12-01

Among the most beautiful findings of the Space Age have been the discoveries of planetary rings. Not only Saturn but also Jupiter, Uranus and Neptune have rings; Saturn’s ring system has structures newly discovered; even Saturn's moon Rhea itself has a ring. All these are apparently supplied by material from the planetary moons (Rhea's ring by Rhea itself). The question naturally arises, why should the Earth not have a ring, and on the other hand, if it does, why has it not been observed? No rings have yet been observed in the inner solar system, but after all, rings in the inner solar system might simply tend to be fainter and more transient than those of the outer solar system: the inner solar system is more affected by the solar wind, and the Sun’s perturbing gravitational influence is greater. J.A. O’Keefe first suggested (1980) that Earth might have a ring system of its own. An Earth ring could account for some climate events. O’Keefe remarked that formation or thickening of a ring system in Earth’s equatorial plane could drive glaciation by deepening the chill of the winter hemisphere. (It is very well established that volcanic dust is an effective agent for the extinction of sunlight; this factor can be overwhelmingly apparent in eclipse observations.) O’Keefe died in 2000 and the speculation was not pursued, but the idea of an Earth ring has a prima facie reasonableness that calls for its renewed consideration. The program of this note is to hypothesize that, as O’Keefe proposed: (a) an Earth ring system exists; (b) it affects Earth's weather and climate; (c) the tektite strewn fields comprise filaments of the ring fallen to Earth's surface on various occasions of disturbance by comets or asteroids. On this basis, and drawing on the world's weather records, together with the Twentieth Century Reanalysis by NCEP/CIRES covering the period 1870-2010 and the geology of the tektite strewn fields, we herein propose the hypothesized Earth ring

Dynamics of the Uranian Rings

NASA Technical Reports Server (NTRS)

Dermott, S. F.

1984-01-01

Some of the problems of the shepherding satellite model of Goldreich ant tremaine are discussed. The following topics are studied: (1) optical depths of the all the observed narrow rings; (2) satellite and ring separation timescales; (3) ring edge sharpness; (4) shock formation in narrow rings; (5) the existence of small satellites near the Uranian rings; and (6) the apse and node alignments of the eccentric and inclined rings.

Uranus rings and two moons

NASA Technical Reports Server (NTRS)

1986-01-01

Voyager 2 has discovered two 'shepherd' satellites associated with the rings of Uranus. The two moons -- designated 1986U7 and 1986U8 -- are seen here on either side of the bright epsilon ring; all nine of the known Uranian rings are visible. The image was taken Jan. 21, 1986, at a distance of 4.1 million kilometers (2.5 million miles) and resolution of about 36 km (22 mi). The image was processed to enhance narrow features. The epsilon ring appears surrounded by a dark halo as a result of this processing; occasional blips seen on the ring are also artifacts. Lying inward from the epsilon ring are the delta, gamma and eta rings; then the beta and alpha rings; and finally the barely visible 4, 5 and 6 rings. The rings have been studied since their discovery in 1977, through observations of how they diminish the light of stars they pass in front of. This image is the first direct observation of all nine rings in reflected sunlight. They range in width from about 100 km (60 mi) at the widest part of the epsilon ring to only a few kilometers for most of the others. The discovery of the two ring moons 1986U7 and 1986U8 is a major advance in our understanding of the structure of the Uranian rings and is in good agreement with theoretical predictions of how these narrow rings are kept from spreading out. Based on likely surface brightness properties, the moons are of roughly 2O- and 3O-km diameter, respectively. The Voyager project is managed for NASA by the Jet Propulsion Laboratory.

Tiny Mimas, Huge Rings

NASA Image and Video Library

2016-11-28

Saturn's icy moon Mimas is dwarfed by the planet's enormous rings. Because Mimas (near lower left) appears tiny by comparison, it might seem that the rings would be far more massive, but this is not the case. Scientists think the rings are no more than a few times as massive as Mimas, or perhaps just a fraction of Mimas' mass. Cassini is expected to determine the mass of Saturn's rings to within just a few hundredths of Mimas' mass as the mission winds down by tracking radio signals from the spacecraft as it flies close to the rings. The rings, which are made of small, icy particles spread over a vast area, are extremely thin -- generally no thicker than the height of a house. Thus, despite their giant proportions, the rings contain a surprisingly small amount of material. Mimas is 246 miles (396 kilometers) wide. This view looks toward the sunlit side of the rings from about 6 degrees above the ring plane. The image was taken in red light with the Cassini spacecraft wide-angle camera on July 21, 2016. The view was obtained at a distance of approximately 564,000 miles (907,000 kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 31 degrees. Image scale is 34 miles (54 kilometers) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA20509

Ossicular fusion and cholesteatoma in auriculo-condylar syndrome: in vivo evidence of arrest of embryogenesis.

PubMed

Propst, Evan J; Ngan, Bo Y; Mount, Richard J; Martin-Munoz, Daniel; Blaser, Susan; Harrison, Robert V; Cushing, Sharon L; Papsin, Blake C

2013-02-01

Auriculo-condylar syndrome (ACS) is a rare condition affecting first branchial arch structures. The types of hearing loss and temporal bone findings in ACS have not been reported. We describe a 14-year-old male with constricted pinnae, mandibular dysostosis, glossoptosis, a high-arched palate, hearing loss, and cholesteatoma. Computed tomography imaging demonstrated malleoincudal joint ankylosis. The fused malleoincudal complex was removed during mastoidectomy for cholesteatoma. Electron microscopy and histopathology of the joint suggested the fusion was congenital. This is the first report of ossicular fusion and cholesteatoma in ACS and the most detailed in vivo evidence of disruption of embryogenesis during malleoincudal joint formation. Copyright © 2012 The American Laryngological, Rhinological, and Otological Society, Inc.

High-temperature CW and pulsed operation in constricted double-heterojunction AlGaAs diode lasers

NASA Technical Reports Server (NTRS)

Botez, D.; Connolly, J. C.; Gilbert, D. B.

1981-01-01

The behavior of constricted double-heterojunction (CDH) diode lasers has been investigated up to 170 C CW and 270 C pulsed. It is found that the temperature-dependent current concentration effect responsible for low threshold-current sensitivity and temperature-invariant external differential quantum efficiency in CDH lasers saturates at about 100 C. It is also found that over a wide temperature interval (180-280 C) the threshold current density has a To value of 40-50 C and that the spontaneous emission becomes increasingly sublinear above 220 C. Both effects are believed to reflect Auger recombination.

On a suspected ring external to the visible rings of Saturn

NASA Technical Reports Server (NTRS)

Feibelman, W. A.; Beebe, R. F.; Smith, B. A.; Cook, A. F., II

1974-01-01

The reexamination of a photograph of Saturn taken on 15 November 1966 when the earth was nearly in the ring plane is investigated which indicates that ring material does exist outside the visible rings, extending to more than 6 Saturnian radii. The observed brightness in blue light was estimated per linear arc second, implying a normal optical thickness, for ice-covered particles.

Inhibitor of prostacyclin production in sporadic haemolytic uraemic syndrome.

PubMed Central

Levin, M; Elkon, K B; Nokes, T J; Buckle, A M; Dillon, M J; Hardisty, R M; Barratt, T M

1983-01-01

Prostacyclin (PGI2) production was diminished when rat aortic rings were incubated with plasma from 5 of 6 patients with the sporadic form of haemolytic uraemic syndrome but was normal in the presence of plasma from 7 patients with the epidemic form of haemolytic uraemic syndrome or from patients with other renal diseases. The reduced PGI2 production was caused by an unstable inhibitor, extractable into polar lipid solvents, in sporadic haemolytic uraemic plasma. These results suggest that there may be at least 2 different pathogenetic mechanisms in epidemic and sporadic haemolytic uraemic syndrome and that the reduced PGI2 production observed in the sporadic type is due to an inhibitor of PGI2 production rather than a deficiency of stimulating factors. PMID:6354101

Deployable Fresnel Rings

NASA Technical Reports Server (NTRS)

Kennedy, Timothy F.; Fink, Patrick W.; Chu, Andrew W.; Lin, Gregory Y.

2014-01-01

Deployable Fresnel rings (DFRs) significantly enhance the realizable gain of an antenna. This innovation is intended to be used in combination with another antenna element, as the DFR itself acts as a focusing or microwave lens element for a primary antenna. This method is completely passive, and is also completely wireless in that it requires neither a cable, nor a connector from the antenna port of the primary antenna to the DFR. The technology improves upon the previous NASA technology called a Tri-Sector Deployable Array Antenna in at least three critical aspects. In contrast to the previous technology, this innovation requires no connector, cable, or other physical interface to the primary communication radio or sensor device. The achievable improvement in terms of antenna gain is significantly higher than has been achieved with the previous technology. Also, where previous embodiments of the Tri-Sector antenna have been constructed with combinations of conventional (e.g., printed circuit board) and conductive fabric materials, this innovation is realized using only conductive and non-conductive fabric (i.e., "e-textile") materials, with the possible exception of a spring-like deployment ring. Conceptually, a DFR operates by canceling the out-of-phase radiation at a plane by insertion of a conducting ring or rings of a specific size and distance from the source antenna, defined by Fresnel zones. Design of DFRs follow similar procedures to those outlined for conventional Fresnel zone rings. Gain enhancement using a single ring is verified experimentally and through computational simulation. The experimental test setup involves a microstrip patch antenna that is directly behind a single-ring DFR and is radiating towards a second microstrip patch antenna. The first patch antenna and DFR are shown. At 2.42 GHz, the DFR improves the transmit antenna gain by 8.6 dB, as shown in Figure 2, relative to the wireless link without the DFR. A figure illustrates the

Mechanical improvement of metal reinforcement rings for a finite ring-shaped superconducting bulk

NASA Astrophysics Data System (ADS)

Huang, Chen-Guang; Zhou, You-He

2018-03-01

As a key technique, reinforcement of type-II superconducting bulks with metal rings can efficiently improve their mechanical properties to enhance the maximum trapped field. In this paper, we study the magnetostrictive and fracture behaviors of a finite superconducting ring bulk reinforced by three typical reinforcing structures composed of metal rings during the magnetizing process by means of the minimization of magnetic energy and the finite element method. After a field-dependent critical current density is adopted, the magnetostriction, pinning-induced stress, and crack tip stress intensity factor are calculated considering the demagnetization effects. The results show that the mechanical properties of the ring bulk are strongly dependent on the reinforcing structure and the material and geometrical parameters of the metal rings. Introducing the metal ring can significantly reduce the hoop stress, and the reduction effect by internal reinforcement is much improved relative to external reinforcement. By comparison, bilateral reinforcement seems to be the best candidate structure. Only when the metal rings have particular Young's modulus and radial thickness will they contribute to improve the mechanical properties the most. In addition, if an edge crack is pre-existing in the ring bulk, the presence of metal rings can effectively avoid crack propagation since it reduces the crack tip stress intensity factor by nearly one order of magnitude.

Ring rotational speed trend analysis by FEM approach in a Ring Rolling process

NASA Astrophysics Data System (ADS)

Allegri, G.; Giorleo, L.; Ceretti, E.

2018-05-01

Ring Rolling is an advanced local incremental forming technology to fabricate directly precise seamless ring-shape parts with various dimensions and materials. In this process two different deformations occur in order to reduce the width and the height of a preform hollow ring; as results a diameter expansion is obtained. In order to guarantee a uniform deformation, the preform is forced toward the Driver Roll whose aim is to transmit the rotation to the ring. The ring rotational speed selection is fundamental because the higher is the speed the higher will be the axial symmetry of the deformation process. However, it is important to underline that the rotational speed will affect not only the final ring geometry but also the loads and energy needed to produce it. Despite this importance in industrial environment, usually, a constant value for the Driver Roll angular velocity is set so to result in a decreasing trend law for the ring rotational speed. The main risk due to this approach is not fulfilling the axial symmetric constrain (due to the diameter expansion) and to generate a high localized ring section deformation. In order to improve the knowledge about this topic in the present paper three different ring rotational speed trends (constant, linearly increasing and linearly decreasing) were investigated by FEM approach. Results were compared in terms of geometrical and dimensional analysis, loads and energies required.

Ring correlations in random networks.

PubMed

Sadjadi, Mahdi; Thorpe, M F

2016-12-01

We examine the correlations between rings in random network glasses in two dimensions as a function of their separation. Initially, we use the topological separation (measured by the number of intervening rings), but this leads to pseudo-long-range correlations due to a lack of topological charge neutrality in the shells surrounding a central ring. This effect is associated with the noncircular nature of the shells. It is, therefore, necessary to use the geometrical distance between ring centers. Hence we find a generalization of the Aboav-Weaire law out to larger distances, with the correlations between rings decaying away when two rings are more than about three rings apart.

Constricted double-heterojunction AlGaAs diode lasers - Structures and electrooptical characteristics

NASA Technical Reports Server (NTRS)

Botez, D.

1981-01-01

Constricted double-heterojunction (CDH) diode lasers are presented as a class of nonplanar-substrate devices for which the lasing cavity is on the least resistive electrical path between the contact and the substrate. Various CDH structures are discussed while treating such topics as liquid-phase epitaxy over channeled substrates, lateral mode control, and current control in nonplanar-substrate devices. Ridge-guide CDH lasers with positive-index lateral mode confinement provides single-mode CW operation to 7 mW/facet at room temperature and to 3 mW/facet at 150 C, while exhibiting light-current characteristics with second-harmonic distortions as low as -57 dB below the fundamental level. Semileaky guide CDH lasers with an asymmetric leaky cavity provide single-mode operation to 15-20 mW/facet CW, and to 50 mW/facet at 50% duty cycle.

Seal ring installation tool

NASA Technical Reports Server (NTRS)

Haselmaier, L. Haynes (Inventor)

2004-01-01

A seal ring tool that allows an installer to position a primary seal ring between hub ends of pipe flanges that are being assembled together. The tool includes a pivoting handle member and extension arms attached to the pivoting handle member. The ends of the arms have side indentation type longitudinal grooves angled toward one another for holding the primary seal ring in place between the hubs of respective pipes that are to be attached together. The arms of the tool can also have flat sides that can be used to abut against an optional second larger seal that is supported within a groove in one of the hub ends so that the second hub end can then be moved against the other side of the primary seal ring. Once the seal ring is positioned between the pipe hubs, the pipe hubs can be moved about the seal ring due to the flat sides of the arms of the tool. The tool eliminates the chances of damaging and contaminating seal rings being installed within pipe hubs that are being attached to one another.

Vertical Skin Paddle Orientation for the Latissimus Dorsi Flap in Breast Reconstruction: A Modification to Simultaneously Correct Inferior Pole Constriction and Improve Projection.

PubMed

Fracol, Megan; Grim, Michelle; Lanier, Steven T; Fine, Neil A

2018-03-01

The latissimus dorsi myocutaneous flap is a reliable and frequently used option to bring vascularized skin and soft tissue to improve the stability and aesthetic result in breast reconstruction. Standard techniques with skin paddle inset in a horizontal or oblique fashion preferentially improve anterior projection (when inset at the mastectomy scar) or lower pole and inframammary fold constriction (when inset into the inframammary fold). Here, the authors describe a modification for inset of the latissimus dorsi myocutaneous flap that improves both anterior projection and lower pole/inframammary fold constriction, and also allows the latissimus muscle to fan out and provide complete implant coverage. The vertical inset modification brings new skin and soft tissue into both the inferior pole and the central mastectomy scar, allowing simultaneous improvement in both areas and full use of the latissimus muscle to cover the implant or expander. Therapeutic, IV.

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).

Barely Bisected Rings

NASA Image and Video Library

2016-09-12

Saturn's shadow stretched beyond the edge of its rings for many years after Cassini first arrived at Saturn, casting an ever-lengthening shadow that reached its maximum extent at the planet's 2009 equinox. This image captured the moment in 2015 when the shrinking shadow just barely reached across the entire main ring system. The shadow will continue to shrink until the planet's northern summer solstice, at which point it will once again start lengthening across the rings, reaching across them in 2019. Like Earth, Saturn is tilted on its axis. And, just as on Earth, as the sun climbs higher in the sky, shadows get shorter. The projection of the planet's shadow onto the rings shrinks and grows over the course of its 29-year-long orbit, as the angle of the sun changes with respect to Saturn's equator. This view looks toward the sunlit side of the rings from about 11 degrees above the ring plane. The image was taken in visible light with the Cassini spacecraft wide-angle camera on Jan. 16, 2015. The view was obtained at a distance of approximately 1.6 million miles (2.5 million kilometers) from Saturn. Image scale is about 90 miles (150 kilometers) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA20498

Particle sizes in Saturn's rings from UVIS stellar occultations 1. Variations with ring region

NASA Astrophysics Data System (ADS)

Colwell, J. E.; Esposito, L. W.; Cooney, J. H.

2018-01-01

The Cassini spacecraft's Ultraviolet Imaging Spectrograph (UVIS) includes a high speed photometer (HSP) that has observed stellar occultations by Saturn's rings with a radial resolution of ∼10 m. In the absence of intervening ring material, the time series of measurements by the HSP is described by Poisson statistics in which the variance equals the mean. The finite sizes of the ring particles occulting the star lead to a variance that is larger than the mean due to correlations in the blocking of photons due to finite particle size and due to random variations in the number of individual particles in each measurement area. This effect was first exploited by Showalter and Nicholson (1990) with the stellar occultation observed by Voyager 2. At a given optical depth, a larger excess variance corresponds to larger particles or clumps that results in greater variation of the signal from measurement to measurement. Here we present analysis of the excess variance in occultations observed by Cassini UVIS. We observe differences in the best-fitting particle size in different ring regions. The C ring plateaus show a distinctly smaller effective particle size, R, than the background C ring, while the background C ring itself shows a positive correlation between R and optical depth. The innermost 700 km of the B ring has a distribution of excess variance with optical depth that is consistent with the C ring ramp and C ring but not with the remainder of the B1 region. The Cassini Division, while similar to the C ring in spectral and structural properties, has different trends in effective particle size with optical depth. There are discrete jumps in R on either side of the Cassini Division ramp, while the C ring ramp shows a smooth transition in R from the C ring to the B ring. The A ring is dominated by self-gravity wakes whose shadow size depends on the occultation geometry. The spectral ;halo; regions around the strongest density waves in the A ring correspond to

The 1995 Saturn Ring-Plane Crossings: Ring Thickness and Small Inner Satellites

NASA Astrophysics Data System (ADS)

Poulet, F.; Sicardy, B.

1996-09-01

The May 22() th and August 10() th, 1995, Saturn ring-plane crossings by the Earth were observed from the 2-m and 1-m telescopes at Pic du Midi, the 2.2-m telescope of the University of Hawaii, and with the Adonis adaptive optics camera at the 3.6-m telescope of the European Southern Observatory (ESO). Observations were made with either a 0.9 mu m or 2.2 mu m (short K) methane band filter. The radial brightness profiles of the rings indicate that the outer F ring dominates the apparent edge-on thickness of the system, with a vertically integrated equivalent width of 0.8-1.0 km near a radius of 130,000 km. The photometric behaviors of the A, B, and C rings and of the Cassini Division have been analyzed using a classical radiative transfer code which includes illumination by the Sun and by the planet. The F ring is modelled as a physically thick ribbon (thickness h) composed of large particles embedded in dust. The observed profiles can be explained if the F ring is both optically thick (tau ~ 0.15-0.25), and physically thick (h at least ~ 1.5 km). The large particles dominate the F ring's photometric behavior in backscattered light. Constraints on the particle properties in the other rings have been derived. The dimming of the rings around August 10, 1995 provided ideal conditions to study the small inner satellites. Besides Janus, Epimetheus and Pandora, two unresolved objects were detected in the ESO frames. They have been identified with the objects 1995S5 and 1995S6, detected several hours later by the Hubble Space Telescope (Nicholson et al. 1996, Science 272, 509--515). Combining the ESO and HST data, we derive orbital and photometric parameters for these objects. In particular, we improve the orbital parameters of 1995S5, whose orbital radius is now close to that of the F ring.

Post-hypoxic constriction of retinal arterioles is impaired during nitric oxide and cyclo-oxygenase inhibition and in diabetic patients without retinopathy.

PubMed

Petersen, Line; Bek, Toke

2017-10-01

Occlusion of retinal vessels leads to retinal ischaemia and hypoxia, which induces vasodilatation in adjacent retinal areas in order to normalize retinal oxygenation. Previous studies have shown that NO and COX products are involved in hypoxia-induced dilatation of retinal arterioles in vitro and in vivo, and that this response is disturbed in patients with diabetes mellitus. However, it is unknown to what extent post-hypoxic recovery of the diameter of retinal arterioles depends on NO and COX products in normal persons and in diabetic patients. The Dynamic Vessel Analyzer (DVA) was used to study the post-hypoxic diameter changes of larger retinal vessels in 20 normal persons, 20 diabetic patients without diabetic retinopathy, and in 18 patients with diabetic maculopathy before and after inhibition of the synthesis of nitric oxide and COX products. In normal persons, the arterioles had re-constricted (p > 0.99) 2 minutes after termination of hypoxia in the absence of antagonists, but not after treatment with L-NMMA and diclofenac (p < 0.01 for all comparisons). In diabetic patients without retinopathy, the arterioles showed no diameter changes after termination of hypoxia during any of the interventions. In patients with diabetic maculopathy hypoxia had not dilated retinal arterioles (p > 0.1 for all comparisons) to allow the study of re-constriction. In all groups, the dilatation of venules remained significantly increased during the post-hypoxic observation period, both in the absence and in the presence of L-NMMA and diclofenac.Post-hypoxic constriction of retinal arterioles depends on NO and COX products, and is impaired in diabetic patients before the development of retinopathy. This disturbance may contribute to the development of diabetic retinopathy, and should be the target of future interventional studies aimed at preventing and treating the disease.ClinicalTrials.gov identifier: NCT01689090.

Saturn's dynamic D ring

USGS Publications Warehouse

Hedman, M.M.; Burns, J.A.; Showalter, M.R.; Porco, C.C.; Nicholson, P.D.; Bosh, A.S.; Tiscareno, M.S.; Brown, R.H.; Buratti, B.J.; Baines, K.H.; Clark, R.

2007-01-01

The Cassini spacecraft has provided the first clear images of the D ring since the Voyager missions. These observations show that the structure of the D ring has undergone significant changes over the last 25 years. The brightest of the three ringlets seen in the Voyager images (named D72), has transformed from a narrow, <40-km wide ringlet to a much broader and more diffuse 250-km wide feature. In addition, its center of light has shifted inwards by over 200 km relative to other features in the D ring. Cassini also finds that the locations of other narrow features in the D ring and the structure of the diffuse material in the D ring differ from those measured by Voyager. Furthermore, Cassini has detected additional ringlets and structures in the D ring that were not observed by Voyager. These include a sheet of material just interior to the inner edge of the C ring that is only observable at phase angles below about 60??. New photometric and spectroscopic data from the ISS (Imaging Science Subsystem) and VIMS (Visual and Infrared Mapping Spectrometer) instruments onboard Cassini show the D ring contains a variety of different particle populations with typical particle sizes ranging from 1 to 100 microns. High-resolution images reveal fine-scale structures in the D ring that appear to be variable in time and/or longitude. Particularly interesting is a remarkably regular, periodic structure with a wavelength of ??? 30 ?? km extending between orbital radii of 73,200 and 74,000 km. A similar structure was previously observed in 1995 during the occultation of the star GSC5249-01240, at which time it had a wavelength of ??? 60 ?? km. We interpret this structure as a periodic vertical corrugation in the D ring produced by differential nodal regression of an initially inclined ring. We speculate that this structure may have formed in response to an impact with a comet or meteoroid in early 1984. ?? 2006 Elsevier Inc. All rights reserved.

Formation of lunar basin rings

USGS Publications Warehouse

Hodges, C.A.; Wilhelms, D.E.

1978-01-01

The origin of the multiple concentric rings that characterize lunar impact basins, and the probable depth and diameter of the transient crater have been widely debated. As an alternative to prevailing "megaterrace" hypotheses, we propose that the outer scarps or mountain rings that delineate the topographic rims of basins-the Cordilleran at Orientale, the Apennine at Imbrium, and the Altai at Nectaris-define the transient cavities, enlarged relatively little by slumping, and thus are analogous to the rim crests of craters like Copernicus; inner rings are uplifted rims of craters nested within the transient cavity. The magnitude of slumping that occurs on all scarps is insufficient to produce major inner rings from the outer. These conclusions are based largely on the observed gradational sequence in lunar central uplifts:. from simple peaks through somewhat annular clusters of peaks, peak and ring combinations and double ring basins, culminating in multiring structures that may also include peaks. In contrast, belts of slump terraces are not gradational with inner rings. Terrestrial analogs suggest two possible mechanisms for producing rings. In some cases, peaks may expand into rings as material is ejected from their cores, as apparently occurred at Gosses Bluff, Australia. A second process, differential excavation of lithologically diverse layers, has produced nested experimental craters and is, we suspect, instrumental in the formation of terrestrial ringed impact craters. Peak expansion could produce double-ring structures in homogeneous materials, but differential excavation is probably required to produce multiring and peak-in-ring configurations in large lunar impact structures. Our interpretation of the representative lunar multiring basin Orientale is consistent with formation of three rings in three layers detected seismically in part of the Moon-the Cordillera (basin-bounding) ring in the upper crust, the composite Montes Rook ring in the underlying

Nine unanswered questions about cytokinesis

PubMed Central

2017-01-01

Experiments on model systems have revealed that cytokinesis in cells with contractile rings (amoebas, fungi, and animals) depends on shared molecular mechanisms in spite of some differences that emerged during a billion years of divergent evolution. Understanding these fundamental mechanisms depends on identifying the participating proteins and characterizing the mechanisms that position the furrow, assemble the contractile ring, anchor the ring to the plasma membrane, trigger ring constriction, produce force to form a furrow, disassemble the ring, expand the plasma membrane in the furrow, and separate the daughter cell membranes. This review reveals that fascinating questions remain about each step. PMID:28807993

Nine unanswered questions about cytokinesis.

PubMed

Pollard, Thomas D

2017-10-02

Experiments on model systems have revealed that cytokinesis in cells with contractile rings (amoebas, fungi, and animals) depends on shared molecular mechanisms in spite of some differences that emerged during a billion years of divergent evolution. Understanding these fundamental mechanisms depends on identifying the participating proteins and characterizing the mechanisms that position the furrow, assemble the contractile ring, anchor the ring to the plasma membrane, trigger ring constriction, produce force to form a furrow, disassemble the ring, expand the plasma membrane in the furrow, and separate the daughter cell membranes. This review reveals that fascinating questions remain about each step. © 2017 Pollard.

Eyeing the E Ring

NASA Image and Video Library

2009-12-24

NASA Cassini spacecraft takes a look at Saturn diffuse E ring which is formed from icy material spewing out of the south pole of the moon Enceladus. The E ring is seen nearly edge-on from slightly above the northern side of Saturn ring plane.

Hot piston ring tests

NASA Technical Reports Server (NTRS)

Allen, David J.; Tomazic, William A.

1987-01-01

As part of the DOE/NASA Automotive Stirling Engine Project, tests were made at NASA Lewis Research Center to determine whether appendix gap losses could be reduced and Stirling engine performance increased by installing an additional piston ring near the top of each piston dome. An MTI-designed upgraded Mod I Automotive Stirling Engine was used. Unlike the conventional rings at the bottom of the piston, these hot rings operated in a high temperature environment (700 C). They were made of a high temperature alloy (Stellite 6B) and a high temperature solid lubricant coating (NASA Lewis-developed PS-200) was applied to the cylinder walls. Engine tests were run at 5, 10, and 15 MPa operating pressure over a range of operating speeds. Tests were run both with hot rings and without to provide a baseline for comparison. Minimum data to assess the potential of both the hot rings and high temperature low friction coating was obtained. Results indicated a slight increase in power and efficiency, an increase over and above the friction loss introduced by the hot rings. Seal leakage measurements showed a significant reduction. Wear on both rings and coating was low.

Tree Rings: Timekeepers of the Past.

ERIC Educational Resources Information Center

Phipps, R. L.; McGowan, J.

One of a series of general interest publications on science issues, this booklet describes the uses of tree rings in historical and biological recordkeeping. Separate sections cover the following topics: dating of tree rings, dating with tree rings, tree ring formation, tree ring identification, sample collections, tree ring cross dating, tree…

Cavity-locked ring down spectroscopy

DOEpatents

Zare, Richard N.; Paldus, Barbara A.; Harb, Charles C.; Spence, Thomas

2000-01-01

Distinct locking and sampling light beams are used in a cavity ring-down spectroscopy (CRDS) system to perform multiple ring-down measurements while the laser and ring-down cavity are continuously locked. The sampling and locking light beams have different frequencies, to ensure that the sampling and locking light are decoupled within the cavity. Preferably, the ring-down cavity is ring-shaped, the sampling light is s-polarized, and the locking light is p-polarized. Transmitted sampling light is used for ring-down measurements, while reflected locking light is used for locking in a Pound-Drever scheme.

Accidental ingestion of BiTine ring and a note on inefficient ring separation forceps.

PubMed

Baghele, Om Nemichand; Baghele, Mangala Om

2011-01-01

Accidental ingestion of medium-to-large instruments is relatively uncommon during dental treatment but can be potentially dangerous. A case of BiTine ring ingestion is presented with a note on inefficient ring separation forceps. A 28-year-old male patient accidentally ingested the BiTine ring (2 cm diameter, 0.5 cm outward projections) while it was being applied to a distoproximal cavity in tooth # 19. The ring placement forceps were excessively flexible; bending of the beaks towards the ring combined with a poor no-slippage mechanism led to sudden disengagement of the ring and accelerated movement towards the pharynx. We followed the patient with bulk forming agents and radiographs. Fortunately the ring passed out without any complications. Checking equipment and methods is as important as taking precautions against any preventable medical emergency. It is the responsibility of the clinician to check, verify and then use any instrument/equipment.

Photometry of Polar-Ring Galaxies

NASA Astrophysics Data System (ADS)

Godínez-Martínez, A.; Watson, A. M.; Matthews, L. D.; Sparke, L. S.

2007-10-01

We have obtained photometry in B and R for seven confirmed or probable polar-ring galaxies from the Polar-Ring Catalog of Whitmore et al. (1990). The rings show a range of colors from B - R ≈ 0.6 to B - R ≈ 1.7. The bluest rings have bright H II regions, which are direct evidence for recent star formation. The minimum age of the reddest ring, that in PRC B-20, is somewhat uncertain because of a lack of knowledge of the internal reddening and metallicity, but appears to be at least 1.2 Gyr. As such, this ring is likely to be stable for at least several rotation periods. This ring is an excellent candidate for future studies that might better determine if it is truly old.

A critical velocity of squeezing a droplet through a circular constriction: implications on ischemic stroke

NASA Astrophysics Data System (ADS)

Zhang, Zhifeng; Drapaca, Corina

2016-11-01

Ischemic stroke accounts for about 87 percent of all stroke cases. In these cases, models of squeezing a droplet through a smaller constriction channel can help better understand the pathology and capillary restoring after a Stroke. In the present research, we analytical expressed the minimum impulse of squeezing a droplet through a circular channel as well as its critical velocity. By comparison with a previously defined critical velocity, we find the difference between these two. Applications of this research in the understanding of ischemic stroke are also discussed. Zhifeng Zhang thanks the support of Robert A. Sebrosky Graduate Fellowship in Engineering Science and Mechanics, the Pennsylvania State University.

Bud detachment in hydra requires activation of fibroblast growth factor receptor and a Rho–ROCK–myosin II signaling pathway to ensure formation of a basal constriction

PubMed Central

Holz, Oliver; Apel, David; Steinmetz, Patrick; Lange, Ellen; Hopfenmüller, Simon; Ohler, Kerstin; Sudhop, Stefanie

2017-01-01

Background: Hydra propagates asexually by exporting tissue into a bud, which detaches 4 days later as a fully differentiated young polyp. Prerequisite for detachment is activation of fibroblast growth factor receptor (FGFR) signaling. The mechanism which enables constriction and tissue separation within the monolayered ecto‐ and endodermal epithelia is unknown. Results: Histological sections and staining of F‐actin by phalloidin revealed conspicuous cell shape changes at the bud detachment site indicating a localized generation of mechanical forces and the potential enhancement of secretory functions in ectodermal cells. By gene expression analysis and pharmacological inhibition, we identified a candidate signaling pathway through Rho, ROCK, and myosin II, which controls bud base constriction and rearrangement of the actin cytoskeleton. Specific regional myosin phosphorylation suggests a crucial role of ectodermal cells at the detachment site. Inhibition of FGFR, Rho, ROCK, or myosin II kinase activity is permissive for budding, but represses myosin phosphorylation, rearrangement of F‐actin and constriction. The young polyp remains permanently connected to the parent by a broad tissue bridge. Conclusions: Our data suggest an essential role of FGFR and a Rho‐ROCK‐myosin II pathway in the control of cell shape changes required for bud detachment. Developmental Dynamics 246:502–516, 2017. © 2017 The Authors Developmental Dynamics published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists PMID:28411398

Improving the Accuracy of Laplacian Estimation with Novel Variable Inter-Ring Distances Concentric Ring Electrodes

PubMed Central

Makeyev, Oleksandr; Besio, Walter G.

2016-01-01

Noninvasive concentric ring electrodes are a promising alternative to conventional disc electrodes. Currently, the superiority of tripolar concentric ring electrodes over disc electrodes, in particular, in accuracy of Laplacian estimation, has been demonstrated in a range of applications. In our recent work, we have shown that accuracy of Laplacian estimation can be improved with multipolar concentric ring electrodes using a general approach to estimation of the Laplacian for an (n + 1)-polar electrode with n rings using the (4n + 1)-point method for n ≥ 2. This paper takes the next step toward further improving the Laplacian estimate by proposing novel variable inter-ring distances concentric ring electrodes. Derived using a modified (4n + 1)-point method, linearly increasing and decreasing inter-ring distances tripolar (n = 2) and quadripolar (n = 3) electrode configurations are compared to their constant inter-ring distances counterparts. Finite element method modeling and analytic results are consistent and suggest that increasing inter-ring distances electrode configurations may decrease the truncation error resulting in more accurate Laplacian estimates compared to respective constant inter-ring distances configurations. For currently used tripolar electrode configuration, the truncation error may be decreased more than two-fold, while for the quadripolar configuration more than a six-fold decrease is expected. PMID:27294933

Improving the Accuracy of Laplacian Estimation with Novel Variable Inter-Ring Distances Concentric Ring Electrodes.

PubMed

Makeyev, Oleksandr; Besio, Walter G

2016-06-10

Noninvasive concentric ring electrodes are a promising alternative to conventional disc electrodes. Currently, the superiority of tripolar concentric ring electrodes over disc electrodes, in particular, in accuracy of Laplacian estimation, has been demonstrated in a range of applications. In our recent work, we have shown that accuracy of Laplacian estimation can be improved with multipolar concentric ring electrodes using a general approach to estimation of the Laplacian for an (n + 1)-polar electrode with n rings using the (4n + 1)-point method for n ≥ 2. This paper takes the next step toward further improving the Laplacian estimate by proposing novel variable inter-ring distances concentric ring electrodes. Derived using a modified (4n + 1)-point method, linearly increasing and decreasing inter-ring distances tripolar (n = 2) and quadripolar (n = 3) electrode configurations are compared to their constant inter-ring distances counterparts. Finite element method modeling and analytic results are consistent and suggest that increasing inter-ring distances electrode configurations may decrease the truncation error resulting in more accurate Laplacian estimates compared to respective constant inter-ring distances configurations. For currently used tripolar electrode configuration, the truncation error may be decreased more than two-fold, while for the quadripolar configuration more than a six-fold decrease is expected.

Embryonic ring closure: Actomyosin rings do the two-step

PubMed Central

2016-01-01

Actomyosin rings drive numerous closure processes, but the mechanisms by which they contract are still poorly understood. In this issue, Xue and Sokac (2016. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201608025) show that actomyosin ring closure during Drosophila melanogaster cellularization uses two steps, only one of which involves Myosin-2. PMID:27799371

Scintillating C Ring

NASA Image and Video Library

2007-01-16

Both luminous and translucent, the C ring sweeps out of the darkness of Saturn's shadow and obscures the planet at lower left. The ring is characterized by broad, isolated bright areas, or "plateaus," surrounded by fainter material. This view looks toward the unlit side of the rings from about 19 degrees above the ringplane. North on Saturn is up. The dark, inner B ring is seen at lower right. The image was taken in visible light with the Cassini spacecraft wide-angle camera on Dec. 15, 2006 at a distance of approximately 632,000 kilometers (393,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 56 degrees. Image scale is 34 kilometers (21 miles) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA08855

Radar imaging of Saturn's rings

NASA Astrophysics Data System (ADS)

Nicholson, Philip D.; French, Richard G.; Campbell, Donald B.; Margot, Jean-Luc; Nolan, Michael C.; Black, Gregory J.; Salo, Heikki J.

2005-09-01

We present delay-Doppler images of Saturn's rings based on radar observations made at Arecibo Observatory between 1999 and 2003, at a wavelength of 12.6 cm and at ring opening angles of 20.1°⩽|B|⩽26.7°. The average radar cross-section of the A ring is ˜77% relative to that of the B ring, while a stringent upper limit of 3% is placed on the cross-section of the C ring and 9% on that of the Cassini Division. These results are consistent with those obtained by Ostro et al. [1982, Icarus 49, 367-381] from radar observations at |B|=21.4°, but provide higher resolution maps of the rings' reflectivity profile. The average cross-section of the A and B rings, normalized by their projected unblocked area, is found to have decreased from 1.25±0.31 to 0.74±0.19 as the rings have opened up, while the circular polarization ratio has increased from 0.64±0.06 to 0.77±0.06. The steep decrease in cross-section is at variance with previous radar measurements [Ostro et al., 1980, Icarus 41, 381-388], and neither this nor the polarization variations are easily understood within the framework of either classical, many-particle-thick or monolayer ring models. One possible explanation involves vertical size segregation in the rings, whereby observations at larger elevation angles which see deeper into the rings preferentially see the larger particles concentrated near the rings' mid-plane. These larger particles may be less reflective and/or rougher and thus more depolarizing than the smaller ones. Images from all four years show a strong m=2 azimuthal asymmetry in the reflectivity of the A ring, with an amplitude of ±20% and minima at longitudes of 67±4° and 247±4° from the sub-Earth point. We attribute the asymmetry to the presence of gravitational wakes in the A ring as invoked by Colombo et al. [1976, Nature 264, 344-345] to explain the similar asymmetry long seen at optical wavelengths. A simple radiative transfer model suggests that the enhancement of the azimuthal

Uranus Rings in False Color

NASA Technical Reports Server (NTRS)

1986-01-01

This false-color view of the rings of Uranus was made from images taken by Voyager 2 on Jan. 21, 1986, from a distance of 4.17 million kilometers (2.59 million miles). All nine known rings are visible here; the somewhat fainter, pastel lines seen between them are contributed by the computer enhancement. Six 15-second narrow-angle images were used to extract color information from the extremely dark and faint rings. Two images each in the green, clear and violet filters were added together and averaged to find the proper color differences between the rings. The final image was made from these three color averages and represents an enhanced, false-color view. The image shows that the brightest, or epsilon, ring at top is neutral in color, with the fainter eight other rings showing color differences between them. Moving down, toward Uranus, we see the delta, gamma and eta rings in shades of blue and green; the beta and alpha rings in somewhat lighter tones; and then a final set of three, known simply as the 4, 5 and 6 rings, in faint off-white tones. Scientists will use this color information to try to understand the nature and origin of the ring material. The resolution of this image is approximately 40 km (25 mi). The Voyager project is managed for NASA by the Jet Propulsion Laboratory.

From coffee ring to spherulites ring of poly(ethylene oxide) film from drying droplet

NASA Astrophysics Data System (ADS)

Hu, Yinchun; Zhang, Xuerong; Qiu, Maibo; Wei, Yan; Zhou, Qiong; Huang, Di

2018-03-01

We discuss how the "spherulites ring" morphology and "coffee ring" profile of PEO film formed by the drying droplet at glass substrate with different heating rate. Upon increasing the heating rate of substrate, it is found that deposited PEO film from drying droplet shows the unusually observed "coffee ring" profile and "spherulites ring" morphology. The main mechanism for this phenomenon is proposed to be an enhanced Marangoni convection which is induced by the increased solute concentration gradient and reduced viscous force above 70 °C. A simple formation mechanism of the unusually observed "coffee ring" profile and "spherulites ring" morphology is proposed. These findings can be exploited to trace the center of Marangoni convection, with potential applications in designing the spherulite patterns of crystalline polymer films in ink-jet printing and self-assembly fields.

Isobaric Tags for Relative and Absolute Quantitation-Based Proteomic Analysis of Patent and Constricted Ductus Arteriosus Tissues Confirms the Systemic Regulation of Ductus Arteriosus Closure.

PubMed

Hong, Haifa; Ye, Lincai; Chen, Huiwen; Xia, Yu; Liu, Yue; Liu, Jinfen; Lu, Yanan; Zhang, Haibo

2015-08-01

We aimed to evaluate global changes in protein expression associated with patency by undertaking proteomic analysis of human constricted and patent ductus arteriosus (DA). Ten constricted and 10 patent human DAs were excised from infants with ductal-dependent heart disease during surgery. Using isobaric tags for relative and absolute quantitation-based quantitative proteomics, 132 differentially expressed proteins were identified. Of 132 proteins, voltage-gated sodium channel 1.3 (SCN3A), myosin 1d (Myo1d), Rho GTPase activating protein 26 (ARHGAP26), and retinitis pigmentosa 1 (RP1) were selected for validation by Western blot and quantitative real-time polymerase chain reaction analyses. Significant upregulation of SCN3A, Myo1d, and RP1 messenger RNA, and protein levels was observed in the patent DA group (all P ≤ 0.048). ARHGAP26 messenger RNA and protein levels were decreased in patent DA tissue (both P ≤ 0.018). Immunohistochemistry analysis revealed that Myo1d, ARHGAP26, and RP1 were specifically expressed in the subendothelial region of constricted DAs; however, diffuse expression of these proteins was noted in the patent group. Proteomic analysis revealed global changes in the expression of proteins that regulate oxygen sensing, ion channels, smooth muscle cell migration, nervous system, immune system, and metabolism, suggesting a basis for the systemic regulation of DA patency by diverse signaling pathways, which will be confirmed in further studies.

Systematic Search for Rings around Kepler Planet Candidates: Constraints on Ring Size and Occurrence Rate

NASA Astrophysics Data System (ADS)

Aizawa, Masataka; Masuda, Kento; Kawahara, Hajime; Suto, Yasushi

2018-05-01

We perform a systematic search for rings around 168 Kepler planet candidates with sufficient signal-to-noise ratios that are selected from all of the short-cadence data. We fit ringed and ringless models to their light curves and compare the fitting results to search for the signatures of planetary rings. First, we identify 29 tentative systems, for which the ringed models exhibit statistically significant improvement over the ringless models. The light curves of those systems are individually examined, but we are not able to identify any candidate that indicates evidence for rings. In turn, we find several mechanisms of false positives that would produce ringlike signals, and the null detection enables us to place upper limits on the size of the rings. Furthermore, assuming the tidal alignment between axes of the planetary rings and orbits, we conclude that the occurrence rate of rings larger than twice the planetary radius is less than 15%. Even though the majority of our targets are short-period planets, our null detection provides statistical and quantitative constraints on largely uncertain theoretical models of the origin, formation, and evolution of planetary rings.

Rings Through Atmosphere

NASA Image and Video Library

2010-05-26

NASA Cassini spacecraft looks toward the limb of Saturn and, on the right of this image, views part of the rings through the planet atmosphere. Saturn atmosphere can distort the view of the rings from some angles.

Ring-through-ring molecular shuttling in a saturated [3]rotaxane

NASA Astrophysics Data System (ADS)

Zhu, Kelong; Baggi, Giorgio; Loeb, Stephen J.

2018-06-01

Mechanically interlocked molecules such as rotaxanes and catenanes comprise two or more components whose motion relative to each other can be controlled. A [2]rotaxane molecular shuttle, for example, consists of an axle bearing two recognition sites and a single macrocyclic wheel that can undergo a to-and-fro motion along the axle—shuttling between the recognition sites. The ability of mechanically interlocked molecules to undergo this type of large-amplitude change is the core mechanism behind almost every interlocked molecular switch or machine, including sophisticated mechanical systems such as a molecular elevator and a peptide synthesizer. Here, as a way to expand the scope of dynamics possible at the molecular level, we have developed a molecular shuttling mechanism involving the exchange of rings between two recognition sites in a saturated [3]rotaxane (one with no empty recognition sites). This was accomplished by passing a smaller ring through a larger one, thus achieving ring-through-ring molecular shuttling.

Constraints on Particle Sizes in Saturn's G Ring from Ring Plane Crossing Observations

NASA Astrophysics Data System (ADS)

Throop, H. B.; Esposito, L. W.

1996-09-01

The ring plane crossings in 1995--96 allowed earth-based observations of Saturn's diffuse rings (Nicholson et al., Nature 272, 1996; De Pater et al. Icarus 121, 1996) at a phase angle of alpha ~ 5 deg . We calculate the G ring reflectance for steady state distributions of dust to km-sized bodies from a range of physical models which track the evolution of the G ring from its initial formation following the disruption of a progenitor satellite (Canup & Esposito 1996, \\ Icarus,\\ in press). We model scattering from the ring's small particles using an exact T-matrix method for nonspherical, absorptive particles (Mishchenko et al. 1996, \\ JGR Atmo., in press), large particles using the phase function and spectrum of Europa, and intermediate particles using a linear combination of the small and large limits. Two distinct particle size distributions from the CE96 model fit the observed spectrum. The first is that of a dusty ring, with the majority of ring reflectance in dust particles of relatedly shallow power law size distribution exponent q ~ 2.5. The second has equal reflectances from a) dust in the range q ~ 3.5 -- 6.5 and b) macroscopic bodies > 1 mm. In this second case, the respective slightly blue and red components combine to form the observed relatively flat spectrum. Although light scattering in backscatter is not sufficient to completely constrain the G ring size distribution, the distributions predicted by the CE96 model can explain the earth-based observations.

Premaxillay retraction in bilateral complete cleft lip and palate with custom made orthopaedic plate having anterior acrylic ring.

PubMed

Raffat, Arsalah; Ijaz, Abida

2009-06-01

To determine retraction and alignment of protruded and rotated premaxillary segment and to measure increase in columellar length by using modified orthopaedic plate with anterior acrylic ring in newborn babies with non syndromic bilateral cleft lip and palate. Pre surgical infant orthopaedic treatment of ten non syndromic bilateral cleft lip and palate new born babies was done. Modified orthopaedic plate with anterior acrylic ring was used. This was adjusted every week by adding increments of 1 mm acrylic along the inner surface contacting labial surface of pre maxillary segment and trimming the same amount along the anterior margin of the plate. Pre and post treatment dental cast and a 1:1 photocopy of dental cast was obtained to analyze the retraction, angulations and arch form. Data was compiled and analyzed in SPSS 10. A significant pre maxillary retraction, correction of rotation as well as increase of columellar length was achieved. The appliance proved most successful being used immediately after birth, making use of plasticity of the neonate cartilage due to maternal estrogen levels. Moreover the appliance maintained arch form facilitated function and rendered initial lip repair easy and tension free.

High-resolution imaging of Saturn's main rings during the Cassini Ring-Grazing Orbits and Grand Finale

NASA Astrophysics Data System (ADS)

Tiscareno, M. S.

2017-12-01

Cassini is ending its spectacular 13-year mission at Saturn with a two-part farewell, during which it has obtained the sharpest and highest-fidelity images ever taken of Saturn's rings. From December 2016 to April 2017, the spacecraft executed 20 near-polar orbits that passed just outside the outer edge of the main rings; these "Ring-Grazing Orbits" provided the mission's best viewing of the A and F rings and the outer B ring. From April to September 2017, the spacecraft is executing 22 near-polar orbits that pass between the innermost D ring and the planet's clouds; this "Grand Finale" provides the mission's best viewing of the C and D rings and the inner B ring. 1) Clumpy BeltsClumpy structure called "straw" was previously observed in parts of the main rings [Porco et al. 2005, Science]. New images show this structure with greater clarity. More surprisingly, new images reveal strong radial variations in the degree and character of clumpiness, which are probably an index for particle properties and interactions. Belts with different clumpiness characteristics are often adjacent to each other and not easily correlated with other ring characteristics. 2) PropellersA "propeller" is a local disturbance in the ring created by an embedded moon [Tiscareno et al. 2006, Nature; 2010, ApJL]. Cassini has observed two classes of propellers: small propellers that swarm in the "Propeller Belts" of the mid-A ring, and "Giant Propellers" whose individual orbits can be tracked in the outer A ring. Both are shown in unprecedented detail in new images. Targeted flybys of Giant Propellers were executed on both the lit and unlit sides of the ring (see figure), yielding enhanced ability to convert brightness to optical depth and surface density. 3) Impact Ejecta CloudsBeing a large and delicate system, Saturn's rings function as a detector of their planetary environment. Cassini images of impact ejecta clouds in the rings previously constrained the population of decimeter

Satiety and eating patterns in two species of constricting snakes.

PubMed

Nielsen, Torben P; Jacobsen, Magnus W; Wang, Tobias

2011-01-10

Satiety has been studied extensively in mammals, birds and fish but very little information exists on reptiles. Here we investigate time-dependent satiation in two species of constricting snakes, ball pythons (Python regius) and yellow anacondas (Eunectes notaeus). Satiation was shown to depend on both fasting time and prey size. In the ball pythons fed with mice of a relative prey mass RPM (mass of the prey/mass of the snake×100) of 15%, we observed a satiety response that developed between 6 and 12h after feeding, but after 24h pythons regained their appetite. With an RPM of 10% the pythons kept eating throughout the experiment. The anacondas showed a non-significant tendency for satiety to develop between 6 and 12h after ingesting a prey of 20% RPM. Unlike pythons, anacondas remained satiated after 24h. Handling time (from strike until prey swallowed) increased with RPM. We also found a significant decrease in handling time between the first and the second prey and a positive correlation between handling time and the mass of the snake. 2010 Elsevier Inc. All rights reserved.

Is alternate rapid maxillary expansion and constriction an effective protocol in the treatment of Class III malocclusion? A systematic review

PubMed Central

Pithon, Matheus Melo; Santos, Nathalia de Lima; dos Santos, Camila Rangel Barreto; Baião, Felipe Carvalho Souza; Pinheiro, Murilo Costa Rangel; Matos, Manoel; Souza, Ianderlei Andrade; de Paula, Rafael Pereira

2016-01-01

ABSTRACT Introduction: the treatment of Class III malocclusion in early age is one of the greatest challenges for orthodontists, and the establishment of more effective treatment method is a constant concern for these professionals. Thus, the objective of this systematic review is to verify the effectiveness of the therapy protocol for alternate rapid maxillary expansion and constriction (Alt-RAMEC) in the early treatment of Class III malocclusion. Methods: searches were performed in the following electronic databases: Cochrane Library, Medline (EBSCO and PubMed), SciELO, LILACS and Scopus. The following inclusion criteria were used: in vivo studies conducted with early intervention (patient in craniofacial development phase) with the use of the Alt-RAMEC protocol. Reviews, case reports, editorials, and studies with syndromic patients or under use of systemic drug were excluded. Duplicates were also excluded. The studies were assessed for methodological quality using the Cochrane tool for assessment of risk of bias, and classified as high or low risk of bias. Results: 53 articles were found. Duplicates exclusion was thus performed and 35 articles remained. After inclusion analysis, only 5 matched the criteria. Two articles were classified as low risk of bias and three as high risk of bias. It was observed that the Alt-RAMEC enable protraction in less time and with better results, promoting greater effectiveness in the protraction treatment of Class III malocclusion. Conclusions: Although there is positive evidence of the effectiveness of early treatment with the Alt-RAMEC protocol in patients with Class III malocclusion, further studies are needed to confirm its effectiveness using long-term methodology. PMID:28125138

Unfocused F Ring

NASA Image and Video Library

2007-04-02

The F ring dissolves into a fuzzy stream of particles -- rather different from its usual appearance of a narrow, bright core flanked by dimmer ringlets. Also notable here is the bright clump of material that flanks the ring core

Annular pancreas (image)

MedlinePlus

Annular pancreas is an abnormal ring or collar of pancreatic tissue that encircles the duodenum (the part of the ... intestine that connects to stomach). This portion of pancreas can constrict the duodenum and block or impair ...

An Instability in Narrow Planetary Rings

NASA Astrophysics Data System (ADS)

Weiss, J. W.; Stewart, G. R.

2003-08-01

We will present our work investigating the behavior of narrow planetary rings with low dispersion velocities. Such narrow a ring will be initially unstable to self-gravitational collapse. After the collapse, the ring is collisionally very dense. At this stage, it is subject to a new instability. Waves appear on the inner and outer edges of the ring within half of an orbital period. The ring then breaks apart radially, taking approximately a quarter of an orbital period of do so. As clumps of ring particles expand radially away from the dense ring, Kepler shear causes these clumps to stretch out azimuthally, and eventually collapse into a new set of dense rings. Small-scale repetitions of the original instability in these new rings eventually leads to a stabilized broad ring with higher dispersion velocities than the initial ring. Preliminary results indicate that this instability may be operating on small scales in broad rings in the wake-like features seen by Salo and others. Some intriguing properties have been observed during this instability. The most significant is a coherence in the epicyclic phases of the particles. Both self-gravity and collisions in the ring operated to create and enforce this coherence. The coherence might also be responsible for the instability to radial expansion. We also observe that guiding centers of the particles do not migrate to the center of the ring during the collapse phase of the ring. In fact, guiding centers move radially away from the core of the ring during this phase, consistent with global conservation of angular momentum. We will show the results of our simulations to date, including movies of the evolution of various parameters. (Audiences members wanting popcorn are advised to bring their own.) This work is supported by a NASA Graduate Student Research Program grant and by the Cassini mission.

Quartz c-axis fabrics in constrictionally strained orthogneisses: implications for the evolution of the Orlica-Śnieżnik Dome, the Sudetes, Poland

NASA Astrophysics Data System (ADS)

Żelaźniewicz, Andrzej; Kromuszczyńska, Olga; Biegała, Natalia

2013-12-01

Żelaźniewicz, A., Kromuszczyńska, O. and Biegała, N. 2013. Quartz c-axis fabrics in constrictionally strained orthogneisses: implications for the evolution of the Orlica-Śnieżnik Dome, the Sudetes, Poland. Acta Geologica Polonica, 63(4), 697-722, Warszawa. The Orlica-Śnieżnik Dome (OSD), NE Bohemian Massif, contains in its core several gneiss variants with protoliths dated at ~500 Ma. In the western limb of the OSD, rodding augen gneisses (Spalona gneiss unit) are mainly L>S tectonites with a prominent stretching lineation. The few quartz LPO studies have produced somewhat discrepant results. Reexamination of these rocks revealed that texture formation was a protracted, multistage process that involved strain partitioning with changing strain rate and kinematics in a general shear regime at temperatures of the amphibolite facies (450-600°C). Quartz c-axis microfabrics show complex yet reproducible patterns that developed under the joint control of strain geometry and temperature; thus the LPOs are mixed features represented by pseudogirdle patterns. Domainal differences in quartz microfabrics (ribbons, tails, quartzo-feldspathic aggregate) are common in the Spalona orthogneisses but uncommon in the sheared migmatitic gneisses. In the latter rocks, the constrictional strain was imposed on the originally planar fabric defined by high-temperature migmatitic layering. The constrictional fabric of the Spalona gneisses may have developed in the hinge zones of kilometer-scale folds, where the elongation occurred parallel to the fold axes. Other occurrences of rodding gneisses throughout the Orlica-Śnieżnik Dome are thought to occupy similar structural positions, which would point to the significance of large-scale folds in the tectonic structure of the dome.

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…

DC-Powered Jumping Ring

ERIC Educational Resources Information Center

Jeffery, Rondo N.; Farhang, Amiri

2016-01-01

The classroom jumping ring demonstration is nearly always performed using alternating current (AC), in which the ring jumps or flies off the extended iron core when the switch is closed. The ring jumps higher when cooled with liquid nitrogen (LN2). We have performed experiments using DC to power the solenoid and find similarities and significant…

Wavelength-tunable optical ring resonators

DOEpatents

Watts, Michael R [Albuquerque, NM; Trotter, Douglas C [Albuquerque, NM; Young, Ralph W [Albuquerque, NM; Nielson, Gregory N [Albuquerque, NM

2009-11-10

Optical ring resonator devices are disclosed that can be used for optical filtering, modulation or switching, or for use as photodetectors or sensors. These devices can be formed as microdisk ring resonators, or as open-ring resonators with an optical waveguide having a width that varies adiabatically. Electrical and mechanical connections to the open-ring resonators are made near a maximum width of the optical waveguide to minimize losses and thereby provide a high resonator Q. The ring resonators can be tuned using an integral electrical heater, or an integral semiconductor junction.

Wavelength-tunable optical ring resonators

DOEpatents

Watts, Michael R [Albuquerque, NM; Trotter, Douglas C [Albuquerque, NM; Young, Ralph W [Albuquerque, NM; Nielson, Gregory N [Albuquerque, NM

2011-07-19

Optical ring resonator devices are disclosed that can be used for optical filtering, modulation or switching, or for use as photodetectors or sensors. These devices can be formed as microdisk ring resonators, or as open-ring resonators with an optical waveguide having a width that varies adiabatically. Electrical and mechanical connections to the open-ring resonators are made near a maximum width of the optical waveguide to minimize losses and thereby provide a high resonator Q. The ring resonators can be tuned using an integral electrical heater, or an integral semiconductor junction.

Helmet latching and attaching ring

NASA Technical Reports Server (NTRS)

Chase, E. W.; Viikinsalo, S. J. (Inventor)

1970-01-01

A neck ring releasably secured to a pressurized garment carries an open-ended ring normally in the engagement position fitted into an annular groove and adapted to fit into a complementary annular groove formed in a helmet. Camming means formed on the inner surface at the end of the helmet engages the open-ended ring to retract the same and allow for one motion donning even when the garment is pressurized. A projection on the end of the split ring is engageable to physically retract the split ring.

A-ring Propeller

NASA Image and Video Library

2010-08-26

A propeller-shaped structure, created by an unseen moon, can be seen in Saturn A ring and looks like a small, dark line interrupting the bright surrounding ring material in the upper left of this image taken by NASA Cassini spacecraft.

Splinters of Rings

NASA Image and Video Library

2009-12-28

Saturn shadow interrupts the planet rings, leaving just thin slivers of the rings visible in this image, which shows a pair of the planet small moons. Helene is in the center top of the image, Epimetheus is in the lower right.

Residual hormone levels in used contraceptive rings as a measurement of adherence to vaginal ring use.

PubMed

Haaland, Richard E; Holder, Angela; Evans-Strickfaden, Tammy; Nyagol, Beatrice; Makanga, Mumbi; Oyaro, Boaz; Humwa, Felix; Williams, Tiffany; McLellan-Lemal, Eleanor; Desai, Mitesh; Huey, Michael J

2017-06-01

This study sought to measure residual contraceptive hormone levels in vaginal rings as an adherence marker for monitoring product use in clinical trials. Residual etonogestrel and ethinyl estradiol levels from used NuvaRings® of 26 self-reported adherent women enrolled in a clinical trial of vaginal ring acceptability were compared to those from 16 women who used NuvaRing® as their contraceptive choice. Twenty-one (81%) clinical trial rings had contraceptive hormone levels within the range of those used as a contraceptive choice. Five returned rings had unused or discordant levels of residual contraceptive hormones. Residual vaginal ring drug levels could help assess adherence in clinical trials. Published by Elsevier Inc.

Saturn Ring-Plane Crossing, may 1995

NASA Astrophysics Data System (ADS)

Bosh, Amanda

1995-07-01

In 1995-1996, the Earth and the Sun will pass through Saturn's ring plane. The Earth will pass through 3 times (22 May 1995, 10 August 1995, 11 Feb 1996), and the Sun will pass through once (19 November 1995). All but the 11 Feb 1996 event will be visible from HST. During the crossings of the Earth through Saturn's ring plane, the rings will become very thin and dark. By monitoring the brightness of the rings as they become very thin, we will be able to determine the time of ring-plane crossing and the residual brightness of the rings at this time. The time of the ring- plane crossing will place additional constraints on the precession rate of Saturn's pole. The recent occultations by Saturn's rings have produced a measurement of this value, but it is not known very well (French et al., 1993; Bosh, 1994; Elliot et al., 1993). A measure of the brightness of the rings in their edge-on configuration, combined with photometric properties of the rings derived from early calibration observations will allow us to determine the thickness of the rings.

The contraceptive vaginal ring, NuvaRing(®), a decade after its introduction.

PubMed

Roumen, Frans J M E; Mishell, Daniel R

2012-12-01

To review the clinical experience with the contraceptive vaginal ring (CVR, NuvaRing(®)) since its introduction over ten years ago. The literature was searched on efficacy, cycle control, safety, user preference and satisfaction of the CVR in comparison with combined oral contraceptives (COCs) and the patch, with special attention to recent developments. The ring has the same working mechanism and contraindications as COCs. Serum levels of steroids are steadier, whereas oestrogenic exposure is lower. Contraceptive efficacy is similar, as are metabolic changes. Cycle control is better, and compliance and continuation rates are equal or higher. Oestrogen-related adverse symptoms appear to be fewer, but reports on the incidence of venous thrombosis are conflicting. Expulsion of the ring is reported by 4% to 20% of women. Local adverse events are the main reason for discontinuation. Acceptability is as high as with COCs and, after structured counselling, the ring is preferred by many women to the pill or the patch. Efficacy of the CVR, and the metabolic changes and adverse events it elicits, are generally comparable to those of COCs, yet oestrogenic exposure is lower and cycle control superior. After counselling, the ring is preferred to the pill by many women.

Concentric ring flywheel without expansion separators

DOEpatents

Kuklo, Thomas C.

1999-01-01

A concentric ring flywheel wherein the adjacent rings are configured to eliminate the need for differential expansion separators between the adjacent rings. This is accomplished by forming a circumferential step on an outer surface of an inner concentric ring and forming a matching circumferential step on the inner surface of an adjacent outer concentric ring. During operation the circumferential steps allow the rings to differentially expand due to the difference in the radius of the rings without the formation of gaps therebetween, thereby eliminating the need for expansion separators to take up the gaps formed by differential expansion.

Galactic rings revisited - I. CVRHS classifications of 3962 ringed galaxies from the Galaxy Zoo 2 Database

NASA Astrophysics Data System (ADS)

Buta, Ronald J.

2017-11-01

Rings are important and characteristic features of disc-shaped galaxies. This paper is the first in a series that re-visits galactic rings with the goals of further understanding the nature of the features and for examining their role in the secular evolution of galaxy structure. The series begins with a new sample of 3962 galaxies drawn from the Galaxy Zoo 2 citizen science data base, selected because zoo volunteers recognized a ring-shaped pattern in the morphology as seen in Sloan Digital Sky Survey colour images. The galaxies are classified within the framework of the Comprehensive de Vaucouleurs revised Hubble-Sandage system. It is found that zoo volunteers cued on the same kinds of ring-like features that were recognized in the 1995 Catalogue of Southern Ringed Galaxies. This paper presents the full catalogue of morphological classifications, comparisons with other sources of classifications and some histograms designed mainly to highlight the content of the catalogue. The advantages of the sample are its large size and the generally good quality of the images; the main disadvantage is the low physical resolution that limits the detectability of linearly small rings such as nuclear rings. The catalogue includes mainly inner and outer disc rings and lenses. Cataclysmic (`encounter-driven') rings (such as ring and polar ring galaxies) are recognized in less than 1 per cent of the sample.

Cerebrovascular regulation in the postural orthostatic tachycardia syndrome (POTS)

NASA Technical Reports Server (NTRS)

Low, P. A.; Novak, V.; Spies, J. M.; Novak, P.; Petty, G. W.

1999-01-01

Patients with the postural orthostatic tachycardia syndrome (POTS) have symptoms of orthostatic intolerance despite having a normal orthostatic blood pressure (BP), which suggests some impairment of cerebrovascular regulation. Cerebrovascular autoregulation refers to the maintenance of normal cerebral blood flow in spite of changing BP. Mechanisms of autoregulation include myogenic, metabolic and neurogenic vasoregulation. Beat-to-beat recording of blood-flow velocity (BFV) is possible using transcranial Doppler imaging. It is possible to evaluate autoregulation by regressing deltaBFV to deltaBP during head-up tilt. A number of dynamic methods, relating deltaBFV to deltaBP during sudden induced changes in BP by occluding then releasing peripheral arterial flow or by the Valsalva maneuver. The deltaBFV to deltaBP provides an index of autoregulation. In orthostatic hypotension, the autoregulated range is typically expanded. In contrast, paradoxical vasoconstriction occurs in POTS because of an increased depth of respiration, resulting in hypocapnic cerebrovascular constriction, and impaired autoregulation.

Evaluating Effects of Floodplain Constriction Along a High Energy Gravel-Bed River: Snake River, WY

NASA Astrophysics Data System (ADS)

Leonard, Christina M.

This study examined approximately 66 km of the Snake River, WY, USA, spanning a natural reach within Grand Teton National Park and a reach immediately downstream that is confined by artificial levees. We linked the channel adjustments observed within these two reaches between 2007 and 2012 to sediment transport processes by developing a morphological sediment budget. A pair of digital elevation models (DEMs) was generated by fusing LiDAR topography with depth estimates derived from optical image data within wetted channels. Errors for both components of the DEMs (LiDAR and optical bathymetry) were propagated through the DEM of difference and sediment budget calculations. Our results indicated that even with the best available methods for acquiring high resolution topographic data over large areas, the uncertainty associated with bed elevation estimates implied that net volumetric changes were not statistically significant. In addition to the terrain analysis, we performed a tracer study to assess the mobility of different grain size classes in different morphological units. Grain sizes, hydraulic conditions, and flow resistance characteristics along cross-sections were used to calculate critical discharges for entrainment, but this bulk characterization of fluid driving forces failed to predict bed mobility. Our results indicated that over seasonal timescales specific grain classes were not preferentially entrained. Surface and subsurface grain size data were used to calculate armoring and dimensionless sediment transport ratios for both reaches; sediment supply exceeded transport capacity in the natural reach and vice versa in the confined reach. We used a conceptual model to describe channel adjustments to lateral constriction by levees. Initially we suggest levees focused flow energy and incised the bed, resulting in bed armoring. Bed armoring promoted channel widening, but levees prevented this and instead the channel migrated more rapidly within the

Rheology modification with ring polymers

NASA Astrophysics Data System (ADS)

Vlassopoulos, Dimitris

It is now established that experimental unconcatenated ring polymers can be purified effectively by means of fractionation at the critical condition. For molecular weights well above the entanglement threshold, purified rings relax stress via power-law (with an exponent of about -0.4), sharply departing from their linear counterparts. Experimental results are in harmony with modeling predictions and simulations. Here, we present results from recent interdisciplinary efforts and discuss two challenges: (i) the nonlinear shear rheology of purified ring melts is also very different from that of unlinked chains. Whereas the latter exhibit features that can be explained, to a first approach, in the framework in the tube model, the former behave akin to unentangled chains with finite extensibility and exhibit much small deformation at steady state. (ii) blends of rings and linear polymers exhibit unique features in different regimes: The addition of minute amounts of linear chains drastically affects ring dynamics. This relates to ring purity and the ability of unlinked linear chains to thread rings. With the help of simulations, it is possible to rationalize the observed surprisingly slow viscoelastic relaxation, which is attributed to ring-linear and ring-ring penetrations. On the other hand, adding small amounts of rings to linear polymers of different molecular weights influences their linear and nonlinear rheology in an unprecedented way. The blend viscosity exceeds that of the slower component (linear) in this non-interacting mixture, and its dependencies on composition and molecular weight ratio are examined, whereas the role of molecular architecture is also addressed. Consequently, closing the ends of a linear chain can serve as a powerful means for molecular manipulation of its rheology. This presentation reflects collaborative efforts with S. Costanzo, Z-C. Yan, R. Pasquino, M. Kaliva, S. Kamble, Y. Jeong, P. Lutz, J. Allgaier, T. Chang, D. Talikis, V

One ring or two? Determination of ring number in carotenoids by lycopene epsilon-cyclases.

PubMed

Cunningham, F X; Gantt, E

2001-02-27

Carotenoids in the photosynthetic membranes of plants typically contain two beta-rings (e.g., beta-carotene and zeaxanthin) or one epsilon- and one beta-ring (e.g., lutein). Carotenoids with two epsilon-rings are uncommon. We reported earlier that the Arabidopsis thaliana lycopene epsilon-cyclase (LCYe) adds one epsilon-ring to the symmetrical linear substrate lycopene, whereas the structurally related lycopene beta-cyclase (LCYb) adds two beta-rings. Here we describe a cDNA encoding LCYe in romaine lettuce (Lactuca sativa var. romaine), one of the few plant species known to accumulate substantial quantities of a carotenoid with two epsilon-rings: lactucaxanthin. The product of the lettuce cDNA, similar in sequence to the Arabidopsis LCYe (77% amino acid identity), efficiently converted lycopene into the bicyclic epsilon-carotene in a heterologous Escherichia coli system. Regions of the lettuce and Arabidopsis epsilon-cyclases involved in the determination of ring number were mapped by analysis of chimeric epsilon-cyclases constructed by using an inverse PCR approach. A single amino acid was found to act as a molecular switch: lettuce LCYe mutant H457L added only one epsilon-ring to lycopene, whereas the complementary Arabidopsis LCYe mutant, L448H, added two epsilon-rings. An R residue in this position also yields a bi-epsilon-cyclase for both the lettuce and Arabidopsis enzymes. Construction and analysis of chimera of related enzymes with differing catalytic activities provide an informative approach that may be of particular utility for studying membrane-associated enzymes that cannot easily be crystallized or modeled to existing crystal structures.

One ring or two? Determination of ring number in carotenoids by lycopene ɛ-cyclases

PubMed Central

Cunningham, Francis X.; Gantt, Elisabeth

2001-01-01

Carotenoids in the photosynthetic membranes of plants typically contain two β-rings (e.g., β-carotene and zeaxanthin) or one ɛ- and one β-ring (e.g., lutein). Carotenoids with two ɛ-rings are uncommon. We reported earlier that the Arabidopsis thaliana lycopene ɛ-cyclase (LCYe) adds one ɛ-ring to the symmetrical linear substrate lycopene, whereas the structurally related lycopene β-cyclase (LCYb) adds two β-rings. Here we describe a cDNA encoding LCYe in romaine lettuce (Lactuca sativa var. romaine), one of the few plant species known to accumulate substantial quantities of a carotenoid with two ɛ-rings: lactucaxanthin. The product of the lettuce cDNA, similar in sequence to the Arabidopsis LCYe (77% amino acid identity), efficiently converted lycopene into the bicyclic ɛ-carotene in a heterologous Escherichia coli system. Regions of the lettuce and Arabidopsis ɛ-cyclases involved in the determination of ring number were mapped by analysis of chimeric ɛ-cyclases constructed by using an inverse PCR approach. A single amino acid was found to act as a molecular switch: lettuce LCYe mutant H457L added only one ɛ-ring to lycopene, whereas the complementary Arabidopsis LCYe mutant, L448H, added two ɛ-rings. An R residue in this position also yields a bi-ɛ-cyclase for both the lettuce and Arabidopsis enzymes. Construction and analysis of chimera of related enzymes with differing catalytic activities provide an informative approach that may be of particular utility for studying membrane-associated enzymes that cannot easily be crystallized or modeled to existing crystal structures. PMID:11226339

The structure of Jupiter’s main ring from New Horizons: A comparison with other ring-moon systems

NASA Astrophysics Data System (ADS)

Chancia, Robert; Hedman, Matthew

2018-04-01

During New Horizon’s Jupiter flyby in 2007, the Long-Range Reconnaissance Imager (LORRI) took several images of the planet’s main ring. The data set contains two extended image-movies of the main ring, along with several brief observations at varying ring azimuths, and a small set of high phase angle images. Thus far, the only published work on the New Horizons Jupiter rings data set found seven bright clumps with sub-km equivalent radii embedded in the main ring (Showalter et al. 2007 Science). In this work, we searched the inner region of the main ring for any structures that might be perturbed at the 3:2 resonances with the rotation of Jupiter’s magnetic field or massive storms. We also examined the structure of the outer main ring in order to assess how it is shaped by the small moons Metis and Adrastea. Some of the features seen in Jupiter’s main ring are similar to those found in other dusty rings around Saturn, Uranus, and Neptune. By comparing these different rings, we can gain a better understanding of how small moons sculpt tenuous rings.

Proton velocity ring-driven instabilities and their dependence on the ring speed: Linear theory

NASA Astrophysics Data System (ADS)

Min, Kyungguk; Liu, Kaijun; Gary, S. Peter

2017-08-01

Linear dispersion theory is used to study the Alfvén-cyclotron, mirror and ion Bernstein instabilities driven by a tenuous (1%) warm proton ring velocity distribution with a ring speed, vr, varying between 2vA and 10vA, where vA is the Alfvén speed. Relatively cool background protons and electrons are assumed. The modeled ring velocity distributions are unstable to both the Alfvén-cyclotron and ion Bernstein instabilities whose maximum growth rates are roughly a linear function of the ring speed. The mirror mode, which has real frequency ωr=0, becomes the fastest growing mode for sufficiently large vr/vA. The mirror and Bernstein instabilities have maximum growth at propagation oblique to the background magnetic field and become more field-aligned with an increasing ring speed. Considering its largest growth rate, the mirror mode, in addition to the Alfvén-cyclotron mode, can cause pitch angle diffusion of the ring protons when the ring speed becomes sufficiently large. Moreover, because the parallel phase speed, v∥ph, becomes sufficiently small relative to vr, the low-frequency Bernstein waves can also aid the pitch angle scattering of the ring protons for large vr. Potential implications of including these two instabilities at oblique propagation on heliospheric pickup ion dynamics are discussed.

Edge-on View of Saturn's Rings

NASA Technical Reports Server (NTRS)

1996-01-01

TOP - This is a NASA Hubble Space Telescope snapshot of Saturn with its rings barely visible. Normally, astronomers see Saturn with its rings tilted. Earth was almost in the plane of Saturn's rings, thus the rings appear edge-on.

In this view, Saturn's largest moon, Titan, is casting a shadow on Saturn. Titan's atmosphere is a dark brown haze. The other moons appear white because of their bright, icy surfaces. Four moons - from left to right, Mimas, Tethys, Janus, and Enceladus - are clustered around the edge of Saturn's rings on the right. Two other moons appear in front of the ring plane. Prometheus is on the right edge; Pandora, on the left. The rings also are casting a shadow on Saturn because the Sun was above the ring plane.

BOTTOM - This photograph shows Saturn with its rings slightly tilted. The moon called Dione, on the lower right, is casting a long, thin shadow across the whole ring system due to the setting Sun on the ring plane. The moon on the upper left of Saturn is Tethys.

Astronomers also are studying the unusual appearance of Saturn's rings. The bottom image displays a faint, narrow ring, the F-ring just outside the main ring, which normally is invisible from Earth. Close to the edge of Saturn's disk, the front section of rings seem brighter and more yellow than the back due to the additional lumination by yellowish Saturn.

The color images were assembled from separate exposures taken August 6 (top) and November 17 (bottom), 1995 with the Wide Field Planetary Camera-2.

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/

Apse-Alignment of the Uranian Rings

NASA Technical Reports Server (NTRS)

Mosqueira, I.; Estrada, P. R.

2000-01-01

An explanation of the dynamical mechanism for apse-alignment of the eccentric Uranian rings is necessary before observations can be used to determine properties such as ring masses, particle sizes, and elasticities. The leading model relies on the ring self-gravity to accomplish this task, yet it yields equilibrium masses which are not in accord with Voyager radio measurements. We explore possible solutions such that the self-gravity and the collisional terms are both involved in the process of apse-alignment. We consider limits that correspond to a hot and a cold ring, and show that pressure terms may play a significant role in the equilibrium conditions for the narrow Uranian rings. In the cold ring case, where the scale height of the ring near periapse is comparable to the ring particle size, we introduce a new pressure correction pertaining to a region of the ring where the particles are locked in their relative positions and jammed against their neighbors, and the velocity dispersion is so low that the collisions are nearly elastic. In this case, we find a solution such that the ring self-gravity maintains apse-alignment against both differential precession (m = 1 mode) and the fluid pressure. We apply this model to the Uranian alpha ring, and show that, compared to the previous self-gravity model, the mass estimate for this ring increases by an order of magnitude. In the case of a hot ring, where the scale height can reach a value as much as fifty times larger than a particle size, we find velocity dispersion profiles that result in pressure forces which act in such a way as to alter the ring equilibrium conditions, again leading to a ring mass increase of an order of magnitude; however, such a velocity dispersion profile would require a different mechanism than is currently envisioned for establishing heating/cooling balance in a finite-sized, inelastic particle ring. Finally, we introduce an important correction to the model of Chiang and Goldreich.

Simulating the Smallest Ring World of Chariklo

NASA Astrophysics Data System (ADS)

Michikoshi, Shugo; Kokubo, Eiichiro

2017-03-01

A ring system consisting of two dense narrow rings has been discovered around Centaur Chariklo. The existence of these rings around a small object poses various questions about their origin, stability, and lifetime. In order to understand the nature of Chariklo’s rings, we perform global N-body simulations of the self-gravitating collisional particle rings for the first time. We find that Chariklo should be denser than the ring material in order to avoid the rapid diffusion of the rings. If Chariklo is denser than the ring material, fine spiral structures called self-gravity wakes occur in the inner ring. These wakes accelerate the viscous spreading of the ring significantly and typically occur on timescales of about 100 {years} for m-sized ring particles, which is considerably shorter than the timescales suggested in previous studies. The existence of these narrow rings implies smaller ring particles or the existence of shepherding satellites.

Recent Simulation Results on Ring Current Dynamics Using the Comprehensive Ring Current Model

NASA Technical Reports Server (NTRS)

Zheng, Yihua; Zaharia, Sorin G.; Lui, Anthony T. Y.; Fok, Mei-Ching

2010-01-01

Plasma sheet conditions and electromagnetic field configurations are both crucial in determining ring current evolution and connection to the ionosphere. In this presentation, we investigate how different conditions of plasma sheet distribution affect ring current properties. Results include comparative studies in 1) varying the radial distance of the plasma sheet boundary; 2) varying local time distribution of the source population; 3) varying the source spectra. Our results show that a source located farther away leads to a stronger ring current than a source that is closer to the Earth. Local time distribution of the source plays an important role in determining both the radial and azimuthal (local time) location of the ring current peak pressure. We found that post-midnight source locations generally lead to a stronger ring current. This finding is in agreement with Lavraud et al.. However, our results do not exhibit any simple dependence of the local time distribution of the peak ring current (within the lower energy range) on the local time distribution of the source, as suggested by Lavraud et al. [2008]. In addition, we will show how different specifications of the magnetic field in the simulation domain affect ring current dynamics in reference to the 20 November 2007 storm, which include initial results on coupling the CRCM with a three-dimensional (3-D) plasma force balance code to achieve self-consistency in the magnetic field.

PROTEIN METABOLISM AND EXCHANGE AS INFLUENCED BY CONSTRICTION OF THE VENA CAVA

PubMed Central

McKee, Frank W.; Schloerb, Paul R.; Schilling, John A.; Tishkoff, Garson H.; Whipple, George H.

1948-01-01

Constriction of inferior vena cava above the diaphragm is used to produce experimental ascites in the dog. This type of experimental ascites drains the body protein reserves, reduces the level of circulating plasma proteins, and in effect is an internal plasmapheresis. As the ascitic fluid is withdrawn and the proteins measured, we observe a production of ascitic protein (80–90 gm. per week) comparable to that removed by plasmapheresis (bleeding and replacement of red cells in saline). High protein diet tends to decrease the ascites but the protein content of the ascitic fluid may increase. Sodium chloride increases notably the volume of the ascites which accumulates and the total ascitic protein output increases. Sodium-free salt mixtures have a negative influence. High protein diet low in sodium salts gives minimal ascitic accumulation under these conditions. The question of circulation of the ascitic fluid is raised—how rapid is the absorption and the related accumulation? PMID:18858638

Compressible Vortex Ring

NASA Astrophysics Data System (ADS)

Elavarasan, Ramasamy; Arakeri, Jayawant; Krothapalli, Anjaneyulu

1999-11-01

The interaction of a high-speed vortex ring with a shock wave is one of the fundamental issues as it is a source of sound in supersonic jets. The complex flow field induced by the vortex alters the propagation of the shock wave greatly. In order to understand the process, a compressible vortex ring is studied in detail using Particle Image Velocimetry (PIV) and shadowgraphic techniques. The high-speed vortex ring is generated from a shock tube and the shock wave, which precedes the vortex, is reflected back by a plate and made to interact with the vortex. The shadowgraph images indicate that the reflected shock front is influenced by the non-uniform flow induced by the vortex and is decelerated while passing through the vortex. It appears that after the interaction the shock is "split" into two. The PIV measurements provided clear picture about the evolution of the vortex at different time interval. The centerline velocity traces show the maximum velocity to be around 350 m/s. The velocity field, unlike in incompressible rings, contains contributions from both the shock and the vortex ring. The velocity distribution across the vortex core, core diameter and circulation are also calculated from the PIV data.

Symmetrical collision of multiple vortex rings

NASA Astrophysics Data System (ADS)

Hernández, R. H.; Reyes, T.

2017-10-01

In this work, we investigate the motion, interaction, and simultaneous collision between many initially stable vortex rings arranged symmetrically in two initial configurations, three and six rings making an angle of 60 and 120° between their straight path lines, respectively. We report results for laminar vortex rings in air obtained through numerical simulations of the ring velocity, pressure, and vorticity fields, both in free flight and during the entire collision. Each collision was studied for small Reynolds numbers R e <1 03 based on both the self-induced velocity and diameter of the ring. The case of three rings produces secondary vortical structures formed by laterally expanding dipolar arms with top and bottom secondary vortex rings. The case of six colliding rings produces, as secondary structures, two big rings moving in opposite directions, a process that reminds us of the head-on collision of two rings [T. T. Lim and T. B. Nickels, "Instability and reconnection in the head-on collision of two vortex rings," Nature 357, 225-227 (1992)] under a hypothetical time reversal transformation. Both collisions display a characteristic kinetic energy evolution where mean collision stages can be identified within the range of Reynolds numbers investigated here.

Bud detachment in hydra requires activation of fibroblast growth factor receptor and a Rho-ROCK-myosin II signaling pathway to ensure formation of a basal constriction.

PubMed

Holz, Oliver; Apel, David; Steinmetz, Patrick; Lange, Ellen; Hopfenmüller, Simon; Ohler, Kerstin; Sudhop, Stefanie; Hassel, Monika

2017-07-01

Hydra propagates asexually by exporting tissue into a bud, which detaches 4 days later as a fully differentiated young polyp. Prerequisite for detachment is activation of fibroblast growth factor receptor (FGFR) signaling. The mechanism which enables constriction and tissue separation within the monolayered ecto- and endodermal epithelia is unknown. Histological sections and staining of F-actin by phalloidin revealed conspicuous cell shape changes at the bud detachment site indicating a localized generation of mechanical forces and the potential enhancement of secretory functions in ectodermal cells. By gene expression analysis and pharmacological inhibition, we identified a candidate signaling pathway through Rho, ROCK, and myosin II, which controls bud base constriction and rearrangement of the actin cytoskeleton. Specific regional myosin phosphorylation suggests a crucial role of ectodermal cells at the detachment site. Inhibition of FGFR, Rho, ROCK, or myosin II kinase activity is permissive for budding, but represses myosin phosphorylation, rearrangement of F-actin and constriction. The young polyp remains permanently connected to the parent by a broad tissue bridge. Our data suggest an essential role of FGFR and a Rho-ROCK-myosin II pathway in the control of cell shape changes required for bud detachment. Developmental Dynamics 246:502-516, 2017. © 2017 The Authors Developmental Dynamics published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists. © 2017 The Authors Developmental Dynamics published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists.

Smoke Ring Physics

ERIC Educational Resources Information Center

Huggins, Elisha

2011-01-01

The behavior of smoke rings, tornados, and quantized vortex rings in superfluid helium has many features in common. These features can be described by the same mathematics we use when introducing Ampere's law in an introductory physics course. We discuss these common features. (Contains 7 figures.)

Inheritance of a Ring Chromosome 21 in a Couple Undergoing In Vitro Fertilization (IVF): A Case Report

PubMed Central

Mazzaschi, Roberto L. P.; Love, Donald R.; Hayes, Ian; George, Alice

2011-01-01

An amniotic fluid sample from an in vitro fertilized pregnancy was referred for cytogenetic analysis based on a Down syndrome screening risk of 1 : 21. Routine cytogenetic analysis showed a nonmosaic karyotype of 46,XX,r(21)(p11.2q22.3), with partial monosomy for chromosome 21 due to a ring chromosome replacing one of the normal homologues. Detailed ultrasound scanning for the remainder of the pregnancy did not reveal any unusual findings. Parental bloods showed that the mother was mosaic for the ring 21 with a karyotype of 46,XX,r(21)(p11.2q22.3)/46,XX and the father had an unrelated Robertsonian translocation, with a karyotype of 45,XY,rob(13;14)(q10;q10). Microarray analysis of cultured amniocytes determined the extent of the deletion of chromosome 21 material in the ring. The parents were given genetic counselling, and a phenotypically normal female baby was delivered at term. This case highlights the importance of karyotyping as an initial step in the management of couples referred for in vitro fertilization. PMID:23074672

Planetary rings - Theory

NASA Technical Reports Server (NTRS)

Borderies, Nicole

1989-01-01

Theoretical models of planetary-ring dynamics are examined in a brief analytical review. The mathematical description of streamlines and streamline interactions is outlined; the redistribution of angular momentum due to collisions between particles is explained; and problems in the modeling of broad, narrow, and arc rings are discussed.

The Dynamics of Dense Planetary Rings.

NASA Astrophysics Data System (ADS)

Mosqueira, Ignacio

1995-01-01

We study the dynamics of a two-mode narrow ring in the case that one of the modes dominates the overall ring perturbation. We use a simple two-streamline self -gravity model, including viscosity, and shepherd satellites. As might be expected, we find that n m = 1 mode appears to be a natural end state for the rings, inasmuch as the presence of a dominant eccentric mode inhibits the growth of other modes, but the reverse is not true. Why some rings exhibit other m values only remains unexplained. Using a modified N-body code to include periodic boundary conditions in a perturbed shear flow, we investigate the role of viscosity on the dynamics of perturbed rings with optical depth tau ~ 1. In particular, we are concerned with rings such that qe = a{de over da} ne 0, where a is the semi-major axis and e is the eccentricity. We confirm the possibility that, for a sufficiently perturbed ring, the angular momentum luminosity may reverse direction with respect to the unperturbed ring (Borderies et al. 1983a). We use observationally constrained parameters for the delta and epsilon Uranian rings, as well as the outer portion of Saturn's B ring. We find that understanding the effects of viscosity for the Uranian rings requires that both local and non-local transport terms be considered if the coefficient of restitution experimentally obtained by Bridges et al. (1984) is appropriate for ring particles. We also find evidence that the criterion for viscous overstability is satisfied in the case of high optical depth rings, as originally proposed by Borderies et al. (1985), making viscous overstability a leading candidate mechanism to explain the non-axisymmetric structure present in the outer portion of Saturn's B ring. To better understand our path-code results we extend a non-local and incompressible fluid model used by Borderies et al. (1985) for dense rings. We incorporate local and non-local transport terms as well as compressibility, while retaining the same number of

Planetary rings as relics of plasma proto-rings rotating in the magnetic field of a central body

NASA Astrophysics Data System (ADS)

Rabinovich, B.

2007-08-01

A possibility is discussed in accordance to hypothesis by H. Alfven, that the rings of large planets are relics of some plasma proto-rings rotating in the magnetic fields of central bodies. A finite-dimensional mathematical model of the system is synthesized using the solution of the boundary-value problem by the Boubnov - Galerkin method. The dipole magnetic field of the central body is assumed to have a small eccentricity, and the dipole axis - to be inclined at a small angle to the central body's axis of rotation which coincides with the ring's rotation axis. The proto-ring is supposed to be thin and narrow and having the same rotating axis as the central body. A medium forming the ring is cold rarefied plasma with high electron density, so that electric conductivity of the medium tends to infinity, as well as the magnetic Reynolds number. The original mathematical model is reduced to a system of finite-difference equations whose asymptotic analytical solution is obtained. Emphasis is placed on the problems of stability of the ring's steady state rotation and quantization of the eigenvalues of nondimensional sector velocity of the ring with respect to the central body. The solutions corresponding to magneto-gravitational and to magneto-gyroscopic waves are considered It is demonstrated that some rings characterized by integral quantum numbers are stable and long-living, while the rings which are associated with half-integer quantum numbers (rings>) are unstable and short-living. As a result, an evolutionally rife rotating plasma ring turns out to be stratified into a large number of narrow elite rings separated by gaps whose position correspond to anti-rings. The regions of possible existence of elite rings in near-central body space are determined. The main result of eigenvalue spectrum's analysis is as follows. Quantum numbers determining elite eigenvalues of the sector velocity of a ring (normalized in a certain manner) coincide with the quantum

Amniotic Constriction Bands: Secondary Deformities and Their Treatments.

PubMed

Drury, Benjamin T; Rayan, Ghazi M

2018-01-01

The purpose of this study was to report the surgical treatment experience of patients with amniotic constriction bands (ACB) over a 35-year interval and detail consequential limb deformities with emphasis on hands and upper extremities, along with the nature and frequency of their surgical treatment methods. Fifty-one patients were identified; 26 were males and 25 females. The total number of deformities was listed. The total number of operations, individual procedures, and operations plus procedures that were done for each patient and their frequency were recorded. The total number of operations was 117, and total number of procedures was 341. More procedures were performed on the upper extremity (85%) than the lower extremity (15%). Including the primary deformity ACB, 16 different hand deformities secondary to ACB were encountered. Sixteen different surgical methods for the upper extremity were utilized; a primary procedure for ACB and secondary reconstructions for all secondary deformities. Average age at the time of the first procedure was 9.3 months. The most common procedures performed, in order of frequency, were excision of ACB plus Z-plasty, release of partial syndactyly, release of fenestrated syndactyly, full-thickness skin grafts, resection of digital bony overgrowth from amputation stumps, and deepening of first and other digital web spaces. Many hand and upper extremity deformities secondary to ACB are encountered. Children with ACB may require more than one operation including multiple procedures. Numerous surgical methods of reconstruction for these children's secondary deformities are necessary in addition to the customary primary procedure of excision of ACB and Z-plasty.

The Search for Ringed Exoplanets

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2017-04-01

Are planetary rings as common in our galaxy as they are in our solar system? A new study demonstrates how we might search for ringed exoplanets and then possibly finds one!Saturns Elsewhere?Artists illustration of the super ring system around exoplanet J1407b. This is the only exoplanet weve found with rings, but its not at all like Saturn. [Ron Miller]Our solar system is filled with moons and planetary rings, so it stands to reason that exoplanetary systems should exhibit the same features. But though weve been in the planet-hunting game for decades, weve only found one exoplanet thats surrounded by a ring system. Whats more, that system J1407b has enormous rings that are vastly different from the modest, Saturn-like rings that we might expect to be more commonplace.Have we not discovered ringed exoplanets just because theyre hard to identify? Or is it because theyre not out there? A team of scientists led by Masataka Aizawa (University of Tokyo) has set out to answer this question by conducting a systematic search for rings around long-period planet candidates.The transit light curve of KIC 10403228, shown with three models: the best-fitting planet-only model (blue) and the two best-fitting planet+ring models (green and red). [Aizawa et al. 2017]The Hunt BeginsWhy long-period planets? Rings are expected to be unstable as the planet gets closer to the central star. Whats more, the planet needs to be far enough away from the stars warmth for the icy rings to exist. The authors therefore select from the collection of candidate transiting planets 89 long-period candidates that might be able to host rings.Aizawa and collaborators then fit single-planet models (with no rings) to the light curves of these planets and search for anomalies curves that arent fit well by these standard models. Particularly suspicious characteristics include a long ingress/egress as the planet moves across the face of the star, and asymmetry of the transit shape.After applying a series of

Fan in the F Ring

NASA Image and Video Library

2010-07-20

This mosaic of images from NASA Cassini spacecraft depicts fan-like structures in Saturn tenuous F ring. Bright features are also visible near the core of the ring. Such features suggest the existence of additional objects in the F ring.

F Ring Bright Core Clumps

NASA Image and Video Library

2010-07-20

Bright clumps of ring material and a fan-like structure appear near the core of Saturn tenuous F ring in this mosaic of images from NASA Cassini spacecraft. Such features suggest the existence of additional objects in the F ring.

Caveolin-1: Functional Insights into Its Role in Muscarine- and Serotonin-Induced Smooth Muscle Constriction in Murine Airways

PubMed Central

Keshavarz, Maryam; Schwarz, Heike; Hartmann, Petra; Wiegand, Silke; Skill, Melanie; Althaus, Mike; Kummer, Wolfgang; Krasteva-Christ, Gabriela

2017-01-01

An increased bronchoconstrictor response is a hallmark in the progression of obstructive airway diseases. Acetylcholine and 5-hydroxytryptamine (5-HT, serotonin) are the major bronchoconstrictors. There is evidence that both cholinergic and serotonergic signaling in airway smooth muscle (ASM) involve caveolae. We hypothesized that caveolin-1 (cav-1), a structural protein of caveolae, plays an important regulatory role in ASM contraction. We analyzed airway contraction in different tracheal segments and extra- and intrapulmonary bronchi in cav-1 deficient (cav-1−/−) and wild-type mice using organ bath recordings and videomorphometry of methyl-beta-cyclodextrin (MCD) treated and non-treated precision-cut lung slices (PCLS). The presence of caveolae was investigated by electron microscopy. Receptor subtypes driving 5-HT-responses were studied by RT-PCR and videomorphometry after pharmacological inhibition with ketanserin. Cav-1 was present in tracheal epithelium and ASM. Muscarine induced a dose dependent contraction in all airway segments. A significantly higher Emax was observed in the caudal trachea. Although, caveolae abundancy was largely reduced in cav-1−/− mice, muscarine-induced airway contraction was maintained, albeit at diminished potency in the middle trachea, in the caudal trachea and in the bronchus without changes in the maximum efficacy. MCD-treatment of PLCS from cav-1−/− mice reduced cholinergic constriction by about 50%, indicating that cholesterol-rich plasma domains account for a substantial portion of the muscarine-induced bronchoconstriction. Notably, cav-1-deficiency fully abrogated 5-HT-induced contraction of extrapulmonary airways. In contrast, 5-HT-induced bronchoconstriction was fully maintained in cav-1-deficient intrapulmonary bronchi, but desensitization upon repetitive stimulation was enhanced. RT-PCR analysis revealed 5-HT1B, 5-HT2A, 5-HT6, and 5-HT7 receptors as the most prevalent subtypes in the airways. The 5-HT-induced-constriction

Fludarabine Phosphate and Total Body Irradiation Followed by a Donor Peripheral Stem Cell Transplant in Treating Patients With Myelodysplastic Syndromes or Myeloproliferative Disorders

ClinicalTrials.gov

2018-03-28

Atypical Chronic Myeloid Leukemia, BCR-ABL1 Negative; Chronic Myelomonocytic Leukemia; de Novo Myelodysplastic Syndrome; Essential Thrombocythemia; Myeloproliferative Neoplasm; Paroxysmal Nocturnal Hemoglobinuria; Polycythemia Vera; Polycythemia Vera, Post-Polycythemic Myelofibrosis Phase; Primary Myelofibrosis; Refractory Anemia; Refractory Anemia With Excess Blasts; Refractory Anemia With Ring Sideroblasts; Refractory Cytopenia With Multilineage Dysplasia; Refractory Cytopenia With Multilineage Dysplasia and Ring Sideroblasts

Researches on the Piston Ring

NASA Technical Reports Server (NTRS)

Ehihara, Keikiti

1944-01-01

In internal combustion engines, steam engines, air compressors, and so forth, the piston ring plays an important role. Especially, the recent development of Diesel engines which require a high compression pressure for their working, makes, nowadays, the packing action of the piston ring far more important than ever. Though a number of papers have been published in regard to researches on the problem of the piston ring, none has yet dealt with an exact measurement of pressure exerted on the cylinder wall at any given point of the ring. The only paper that can be traced on this subject so far is Mr. Nakagawa's report on the determination of the relative distribution of pressure on the cylinder wall, but the measuring method adopted therein appears to need further consideration. No exact idea has yet been obtained as to how the obturation of gas between the piston and cylinder, the frictional resistance of the piston, and the wear of the cylinder wall are affected by the intensity and the distribution of the radial pressure of the piston ring. Consequently, the author has endeavored, by employing an apparatus of his own invention, to get an exact determination of the pressure distribution of the piston ring. By means of a newly devised ring tester, to which piezoelectricity of quartz was applied, the distribution of the radial pressure of many sample rings on the market was accurately determined. Since many famous piston rings show very irregular pressure distribution, the author investigated and achieved a manufacturing process of the piston ring which will exert uniform pressure on the cylinder wall. Temperature effects on the configuration and on the mean spring power have also been studied. Further, the tests were performed to ascertain how the gas tightness of the piston ring may be affected by the number or spring power. The researches as to the frictional resistance between the piston ring and the cylinder wall were carried out, too. The procedure of study, and

Uranus Ring System

NASA Image and Video Library

1996-01-29

This image captured by NASA's Voyager 2 in 1986 revealed a continuous distribution of small particles throughout the Uranus ring system. This unique geometry, the highest phase angle at which Voyager imaged the rings, allowed us to see lanes of fine dust. http://photojournal.jpl.nasa.gov/catalog/PIA00142

Moonlets wandering on a leash-ring

NASA Astrophysics Data System (ADS)

Winter, O. C.; Mourão, D. C.; Giuliatti Winter, S. M.; Spahn, F.; da Cruz, C.

2007-09-01

Since the Voyager flybys, embedded moonlets have been proposed to explain some of the surprising structures observed in Saturn's narrow F ring. Experiments conducted with the Cassini spacecraft support this suggestion. Images of the F ring show bright compact spots, and seven occultations of stars by the F ring, monitored by ultraviolet and infrared experiments, revealed nine events of high optical depth. These results point to a large number of such objects, but it is not clear whether they are solid moonlets or rather loose particle aggregates. Subsequent images suggested an irregular motion of these objects so that a determination of their orbits consistent with the F ring failed. Some of these features seem to cross the whole ring. Here we show that these observations are explained by chaos in the F ring driven mainly by the `shepherd' moons Prometheus and Pandora. It is characterized by a rather short Lyapunov time of about a few hundred orbital periods. Despite this chaotic diffusion, more than 93 per cent of the F-ring bodies remain confined within the F ring because of the shepherding, but also because of a weak radial mobility contrasted by an effective longitudinal diffusion. This chaotic stirring of all bodies involved prevents the formation of `propellers' typical of moonlets, but their frequent ring crossings explain the multiple radial `streaks' seen in the F ring. The related `thermal' motion causes more frequent collisions between all bodies which steadily replenish F-ring dust and allow for ongoing fragmentation and re-accretion processes (ring recycling).

Saturn's E Ring in Ultraviolet Light

NASA Technical Reports Server (NTRS)

2002-01-01

Visible from Earth only at times of ring plane crossing, Saturn's tenuous E Ring was discovered during the 1966 crossings and imaged again in 1980. From these observations, its color is known to be distinctively blue. The E Ring was captured in ultraviolet light for the first time in this image taken with HST's Wide Field and Planetary Camera on 9 August 1995. Five individual images taken with a broadband 3000 A filter were combined, amounting to a total exposure time of 2200 sec. Shorter exposure images were also obtained with blue, red and infrared filters in order to characterize the ring's color. The peak brightness of the E Ring occurs at 3.9 Saturn radii (235,000 km), coinciding with the orbit of Enceladus. In the HST images it can be traced out to a maximum distance of approximately 8 Rs (480,000 km). The vertical thickness of the ring, on the other hand, is smallest at Enceladus' orbit, with the ring puffing up noticeably at larger distances to 15,000 km or more thick. Also visible in this image, between the E Ring and the overexposed outermost part of the main rings near the lower edge of the frame, is the tenuous, thin, 6000 km-wide G Ring at 2.8 Rs (170,000 km). This is among the first earth-based observations of the G Ring, which was discovered by the Pioneer 11 spacecraft in 1979. Noticeably thinner than the E Ring and more neutral in color, the G Ring is thought to be composed of larger, macroscopic particles, and to pose a significant hazard to spacecraft. The faint diagonal band in the lower right part of the image is due to diffracted light from the heavily-overexposed planet. Credit: Phil Nicholson (Cornell University), Mark Showalter (NASA-Ames/Stanford) and NASA

Uranus Rings and Two Moons

NASA Image and Video Library

1999-06-19

Voyager 2 has discovered two hepherd satellites associated with the rings of Uranus. The two moons, designated 1986U7 and 1986U8, are seen here on either side of the bright epsilon ring; all nine of the known Uranian rings are visible.

Nuclear Rings in Galaxies - A Kinematic Perspective

NASA Technical Reports Server (NTRS)

Mazzuca, Lisa M.; Swaters, Robert A.; Knapen, Johan H.; Veilleux, Sylvain

2011-01-01

We combine DensePak integral field unit and TAURUS Fabry-Perot observations of 13 nuclear rings to show an interconnection between the kinematic properties of the rings and their resonant origin. The nuclear rings have regular and symmetric kinematics, and lack strong non-circular motions. This symmetry, coupled with a direct relationship between the position angles and ellipticities of the rings and those of their host galaxies, indicate the rings are in the same plane as the disc and are circular. From the rotation curves derived, we have estimated the compactness (v(sup 2)/r) up to the turnover radius, which is where the nuclear rings reside. We find that there is evidence of a correlation between compactness and ring width and size. Radially wide rings are less compact, and thus have lower mass concentration. The compactness increases as the ring width decreases. We also find that the nuclear ring size is dependent on the bar strength, with weaker bars allowing rings of any size to form.

Adolescent Experiences with the Vaginal Ring

PubMed Central

Epstein, Laura B.; Sokal-Gutierrez, Karen; Ivey, Susan L.; Raine, Tina; Auerswald, Colette

2011-01-01

Purpose To understand racial/ethnic minority adolescent females’ experiences with the vaginal ring. Methods We conducted in-depth interviews with a clinic-based sample of 32 young women aged 15–24 years who had used the vaginal ring. Results Qualitative analysis using grounded theory revealed that adolescents undergo a multi-stage process when trying the ring and adopting ring use. These stages include hearing about the ring, initial reactions, first experiences with insertion and removal, and first sexual experiences. Adolescents subsequently enter an assessment and adjustment stage in which they decide whether to adopt or discontinue ring use. Ultimately they share their experiences with friends. Conclusions The model developed provides a context within which providers may advise adolescents as they begin use of the ring. Some specific recommendations are offered. PMID:18565439

Amnioserosa cell constriction but not epidermal actin cable tension autonomously drives dorsal closure.

PubMed

Pasakarnis, Laurynas; Frei, Erich; Caussinus, Emmanuel; Affolter, Markus; Brunner, Damian

2016-11-01

Tissue morphogenesis requires coordination of multiple force-producing components. During dorsal closure in fly embryogenesis, an epidermis opening closes. A tensioned epidermal actin/MyosinII cable, which surrounds the opening, produces a force that is thought to combine with another MyosinII force mediating apical constriction of the amnioserosa cells that fill the opening. A model proposing that each force could autonomously drive dorsal closure was recently challenged by a model in which the two forces combine in a ratchet mechanism. Acute force elimination via selective MyosinII depletion in one or the other tissue shows that the amnioserosa tissue autonomously drives dorsal closure while the actin/MyosinII cable cannot. These findings exclude both previous models, although a contribution of the ratchet mechanism at dorsal closure onset remains likely. This shifts the current view of dorsal closure being a combinatorial force-component system to a single tissue-driven closure event.

Biotransformation of two β-secretase inhibitors including ring opening and contraction of a pyrimidine ring.

PubMed

Lindgren, Anders; Eklund, Göran; Turek, Dominika; Malmquist, Jonas; Swahn, Britt-Marie; Holenz, Jörg; von Berg, Stefan; Karlström, Sofia; Bueters, Tjerk

2013-05-01

Recently, the discovery of the aminoisoindoles as potent and selective inhibitors of β-secretase was reported, including the close structural analogs compound (S)-1-pyridin-4-yl-4-fluoro-1-(3-(pyrimidin-5-yl)phenyl)-1H-isoindol-3-amine [(S)-25] and (S)-1-(2-(difluoromethyl)pyridin-4-yl)-4-fluoro-1-(3-(pyrimidin-5-yl)phenyl)-1H-isoindol-3-amine hemifumarate (AZD3839), the latter being recently progressed to the clinic. The biotransformation of (S)-25 was investigated in vitro and in vivo in rat, rabbit, and human and compared with AZD3839 to further understand the metabolic fate of these compounds. In vitro, CYP3A4 was the major responsible enzyme and metabolized both compounds to a large extent in the commonly shared pyridine and pyrimidine rings. The main proposed metabolic pathways in various in vitro systems were N-oxidation of the pyridine and/or pyrimidine ring and conversion to 4-pyrimidone and pyrimidine-2,4-dione. Both compounds were extensively metabolized, and more than 90% was excreted in feces after intravenous administration of radiolabeled compound to the rat. Here, the main pathways were N-oxidation of the pyridine and/or pyrimidine ring and a ring contraction of the pyrimidine ring into an imidazole ring. Ring-contracted metabolites accounted for 25% of the total metabolism in the rat for (S)-25, whereas the contribution was much smaller for AZD3839. This metabolic pathway was not foreseen on the basis of the obtained in vitro data. In conclusion, we discovered an unusual metabolic pathway of aryl-pyrimidine-containing compounds by a ring-opening reaction followed by elimination of a carbon atom and a ring closure to form an imidazole ring.

The Rings of Saturn

NASA Astrophysics Data System (ADS)

Cuzzi, J. N.; Filacchione, G.; Marouf, E. A.

2018-03-01

One could become an expert on Saturn's iconic rings pretty easily in the early 1970s, as very little was known about them beyond the distinction between the A, B, and C rings, and the Cassini Division or "gap" between rings A and B (Alexander, 1962; Bobrov, 1970). Water ice was discovered spectroscopically on the ring particle surfaces, and radar and microwave emission observations proved that the particles must be centimeters to meters in size, consisting primarily, not just superficially, of water ice (Pollack, 1975). While a 2:1 orbital resonance with Mimas had long been suspected of having something to do with the Cassini Division, computers of the time were unable to model the subtle dynamical effects that we now know to dominate ring structure. This innocent state of affairs was exploded by the Voyager 1 and 2 encounters in 1980 and 1981. Spectacular images revealed filigree structure and odd regional color variations, and exquisitely detailed radial profiles of fluctuating particle abundance were obtained from the first stellar and radio occultations, having resolution almost at the scale of single particles. Voyager-era understanding was reviewed by Cuzzi et al. (1984) and Esposito et al. (1984). While the Voyager data kept ring scientists busy for decades, planning which led to the monumentally successful NASA-ESA-ASI Cassini mission, which arrived in 2004, had been under way even before Voyager got to Saturn. A review of pre-Cassini knowledge of Saturn's Rings can be found in Orton et al. (2009). This chapter will build on recent topical and process-specific reviews that treat the gamut of ring phenomena and its underlying physics in considerable detail (Colwell et al., 2009; Cuzzi et al., 2009; Horányi et al., 2009; Schmidt et al., 2009; Esposito, 2010; Tiscareno, 2013b; Esposito, 2014). We will follow and extend the general organization of Cuzzi et al. (2010), the most recent general discussion of Saturn's rings. For brevity and the benefit of the

What confines the rings of Saturn?

NASA Astrophysics Data System (ADS)

Tajeddine, Radwan; Nicholson, Philip D.; El Moutamid, Maryame; Longaretti, Pierre-Yves; Burns, Joseph A.

2017-10-01

The viscous spreading of planetary rings is believed to be counteracted by satellite torques, either through an individual resonance or through overlapping resonances (when the satellite is close to the ring edge). For the A ring of Saturn, it has been commonly believed that the satellite Janus alone can prevent the ring from spreading via its 7:6 Lindblad resonance. We discuss this common misconception and show that, in reality, the A ring is confined by the contributions from the group of satellites Pan, Atlas, Prometheus, Pandora, Janus, Epimetheus, and Mimas, whose resonances gradually decrease the angular momentum flux transported outward through the ring via density and bending waves. We further argue that this decrease in angular momentum flux occurs through the mechanism of ‘flux reversal’.We find that the Janus 7:6 torque is relatively feeble, as is the comparable torque of the nearby small satellite Atlas, each amounting to less than one-tenth of the angular momentum transport carried by the A ring. But the cumulative torques of the many other satellite resonances in the A ring sufficiently reduce the angular momentum flux through the rings so that the torques due to Janus and Atlas are effective in confining the outer edge of the ring.Furthermore, we use the magnitude of the satellites’ resonance torques to estimate the effective viscosity profile across the A ring, showing that it decreases from ~50 cm2 s-1 at the inner edge to less than ~11 cm2 s-1 at the outer edge. The gradual estimated decrease of the angular momentum flux and effective viscosity are roughly consistent with results obtained by balancing the shepherding torques from Pan and Daphnis with the viscous torque at the edges of the Encke and Keeler gaps, as well as the edge of the A ring.On the other hand, the Mimas 2:1 Lindblad resonance alone seems to be capable of confining the edge of the B ring, and contrary to the situation in the A ring, we show that the effective viscosity

Slide-Ring Materials Using Cyclodextrin.

PubMed

Ito, Kohzo

2017-01-01

We have recently synthesized slide-ring materials using cyclodextrin by cross-linking polyrotaxanes, a typical supramolecule. The slide-ring materials have polymer chains with bulky end groups topologically interlocked by figure-of-eight shaped junctions. This indicates that the cross-links can pass through the polymer chains similar to pulleys to relax the tension of the backbone polymer chains. The slide-ring materials also differ from conventional polymers in that the entropy of rings affects the elasticity. As a result, the slide-ring materials show quite small Young's modulus not proportional to the cross-linking density. This concept can be applied to a wide variety of polymeric materials as well as gels. In particular, the slide-ring materials show remarkable scratch-proof properties for coating materials for automobiles, cell phones, mobile computers, and so on. Further current applications include vibration-proof insulation materials for sound speakers, highly abrasive polishing media, dielectric actuators, and so on.

Finite element method modeling to assess Laplacian estimates via novel variable inter-ring distances concentric ring electrodes.

PubMed

Makeyev, Oleksandr; Besio, Walter G

2016-08-01

Noninvasive concentric ring electrodes are a promising alternative to conventional disc electrodes. Currently, superiority of tripolar concentric ring electrodes over disc electrodes, in particular, in accuracy of Laplacian estimation has been demonstrated in a range of applications. In our recent work we have shown that accuracy of Laplacian estimation can be improved with multipolar concentric ring electrodes using a general approach to estimation of the Laplacian for an (n + 1)-polar electrode with n rings using the (4n + 1)-point method for n ≥ 2. This paper takes the next step toward further improving the Laplacian estimate by proposing novel variable inter-ring distances concentric ring electrodes. Derived using a modified (4n + 1)-point method, linearly increasing and decreasing inter-ring distances tripolar (n = 2) and quadripolar (n = 3) electrode configurations are compared to their constant inter-ring distances counterparts using finite element method modeling. Obtained results suggest that increasing inter-ring distances electrode configurations may decrease the estimation error resulting in more accurate Laplacian estimates compared to respective constant inter-ring distances configurations. For currently used tripolar electrode configuration the estimation error may be decreased more than two-fold while for the quadripolar configuration more than six-fold decrease is expected.

Combination Chemotherapy With or Without Bone Marrow Transplantation in Treating Children With Acute Myelogenous Leukemia or Myelodysplastic Syndrome

ClinicalTrials.gov

2013-01-15

Childhood Acute Erythroleukemia (M6); Childhood Acute Megakaryocytic Leukemia (M7); Childhood Acute Monoblastic Leukemia (M5a); Childhood Acute Monocytic Leukemia (M5b); Childhood Acute Myeloblastic Leukemia With Maturation (M2); Childhood Acute Myeloblastic Leukemia Without Maturation (M1); Childhood Acute Myelomonocytic Leukemia (M4); Childhood Myelodysplastic Syndromes; Chronic Myelomonocytic Leukemia; de Novo Myelodysplastic Syndromes; Refractory Anemia; Refractory Anemia With Excess Blasts; Refractory Anemia With Excess Blasts in Transformation; Refractory Anemia With Ringed Sideroblasts; Secondary Myelodysplastic Syndromes; Untreated Childhood Acute Myeloid Leukemia and Other Myeloid Malignancies