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.

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

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

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.

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

Pericardiectomy as a diagnostic and therapeutic procedure.

PubMed

Konik, Ewa; Geske, Jeffrey; Edwards, William; Gersh, Bernard

2016-11-14

A 70-year-old man presented with recent onset, predominantly right-sided heart failure. Echocardiogram demonstrated features of hypertensive heart disease and was suggestive of, but non-diagnostic for, constrictive pericarditis (CP). CT demonstrated mild pericardial thickening. Right heart catheterisation showed elevation and equalisation of diastolic pressures in all cardiac chambers with early rapid filling, minimal ventricular interdependence, and no dissociation of intrathoracic and intracardiac pressures. While several features pointed towards CP, the minimal ventricular interdependence and no dissociation of intrathoracic and intracardiac pressures suggested other pathology. Diagnostic pericardiectomy was performed, after which the central venous pressure decreased from 22 to 12 mm Hg. Pathology revealed pericardial fibrosis. The patient experienced sustained resolution of his heart failure. A potential explanation for lack of CP criteria was the presence of hypertensive heart disease. CP needs to be considered when approaching patients with heart failure as diagnostic evaluation can be multifaceted and treatment curative. 2016 BMJ Publishing Group Ltd.

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

Mechanism of Cytokinetic Contractile Ring Constriction in Fission Yeast

PubMed Central

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

2014-01-01

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

Patterned Ferroelectric Films for Tunable Microwave Devices

NASA Technical Reports Server (NTRS)

Miranda, Felix A.; Mueller, Carl H.

2008-01-01

Tunable microwave devices based on metal terminals connected by thin ferroelectric films can be made to perform better by patterning the films to include suitably dimensioned, positioned, and oriented constrictions. The patterns can be formed during fabrication by means of selective etching processes. If the width of the ferroelectric film in such a device is reduced at one or more locations, then both the microwave field and any applied DC bias (tuning) electric field become concentrated at those locations. The magnitudes of both the permittivity and the dielectric loss of a ferroelectric material are reduced by application of a DC field. Because the concentration of the DC field in the constriction(s) magnifies the permittivity- and loss-reducing effects of the applied DC voltage, the permittivity and dielectric loss in the constriction(s) are smaller in the constriction(s) than they are in the wider parts of the ferroelectric film. Furthermore, inasmuch as displacement current must flow through either the constriction(s) or the low-loss dielectric substrate, the net effect of the constriction(s) is equivalent to that of incorporating one or more low-loss, low-permittivity region(s) in series with the high-loss, high-permittivity regions. In a series circuit, the properties of the low-capacitance series element (in this case, the constriction) dominate the overall performance. Concomitantly, the capacitance between the metal terminals is reduced. By making the capacitance between the metal terminals small but tunable, a constriction increases the upper limit of the frequency range amenable to ferroelectric tuning. The present patterning concept is expected to be most advantageous for devices and circuits that must operate at frequencies from about 4 to about 60 GHz. A constriction can be designed such that the magnitude of the microwave electric field and the effective width of the region occupied by the microwave electric field become functions of the applied DC electric field, so that tunability is enhanced. It should even be possible to design the constriction to obtain a specific tuning-versus-voltage profile.

Human immunodeficiency virus-associated heart failure in sub-Saharan Africa: evolution in the epidemiology, pathophysiology, and clinical manifestations in the antiretroviral era.

PubMed

Ntusi, Ntobeko A B; Ntsekhe, Mpiko

2016-09-01

The survival of patients with human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) who have access to highly active antiretroviral therapy (ART) has dramatically increased in recent times. This review focuses on HIV-associated heart failure in sub-Saharan Africa (SSA). In HIV infected persons, heart failure may be related to pathology of the pericardium, the myocardium, the valves, the conduction system, or the coronary and pulmonary vasculature. HIV-associated heart failure can be because of direct consequences of HIV infection, autoimmune reactions, pro-inflammatory cytokines, opportunistic infections (OIs) or neoplasms, use of ART or therapy for OIs and presence of traditional cardiovascular risk factors. Myocardial involvement includes diastolic dysfunction, asymptomatic left ventricular dysfunction, cardiomyopathy, myocarditis, fibrosis, and steatosis. Pericardial diseases include pericarditis, pericardial effusions (rarely causing tamponade), pericardial constriction, and effusive-constrictive syndromes. Coronary artery disease is commonly reported in industrial nations, although its prevalence is thought to be low in HIV-infected persons from SSA. © 2016 The Authors. ESC Heart Failure published by John Wiley & Sons Ltd on behalf of the European Society of Cardiology.

The right atrium: gateway to the heart--anatomic and pathologic imaging findings.

PubMed

Malik, Sachin B; Kwan, Damon; Shah, Amar B; Hsu, Joe Y

2015-01-01

Knowledge of right atrial anatomic and pathologic imaging findings and associated clinical symptoms is important to avoid false-positive diagnoses and missed findings. Complete evaluation of the heart often requires a multimodality approach that includes radiography, echocardiography, computed tomography (CT), magnetic resonance (MR) imaging, and invasive angiography. In general, CT provides the highest spatial resolution of these modalities at the cost of radiation exposure to the patient. Echocardiography and MR imaging offer complementary and detailed information for functional evaluation without added radiation exposure. The advantages and disadvantages of each modality for the evaluation of right atrial anatomic structure, size, and pathologic findings are discussed. Cardiac MR imaging is the reference standard for evaluation of right atrial size and volume but often is too time consuming and resource intensive to perform in routine clinical practice. Therefore, established reference ranges for two-dimensional transthoracic echocardiography are often used. Right atrial pathologic findings can be broadly categorized into (a) congenital anomalies (cor triatriatum dexter, Ebstein anomaly, and aneurysm), (b) disorders of volume (tricuspid regurgitation, pathologic mimics such as a pseudoaneurysm, and atrial septal defect), (c) disorders of pressure (tricuspid stenosis, restrictive cardiomyopathy, and constrictive pericarditis), and (d) masses (pseudomasses, thrombus, lipomatous hypertrophy of the interatrial septum, lipoma, myxoma, sarcoma, and metastatic disease). Familiarity with each pathologic entity and its treatment options is essential to ensure that appropriate imaging modalities are selected. Online supplemental material is available for this article. RSNA, 2015

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.

Biventricular structural and functional responses to aortic constriction in a rabbit model of chronic right ventricular pressure overload.

PubMed

Apitz, Christian; Honjo, Osami; Humpl, Tilman; Li, Jing; Assad, Renato S; Cho, Mi Y; Hong, James; Friedberg, Mark K; Redington, Andrew N

2012-12-01

Chronic right ventricular (RV) pressure overload results in pathologic RV hypertrophy and diminished RV function. Although aortic constriction has been shown to improve systolic function in acute RV failure, its effect on RV responses to chronic pressure overload is unknown. Adjustable vascular banding devices were placed on the main pulmonary artery and descending aorta. In 5 animals (sham group), neither band was inflated. In 9 animals (PAB group), only the pulmonary arterial band was inflated, with adjustments on a weekly basis to generate systemic or suprasystemic RV pressure at 28 days. In 9 animals, both pulmonary arterial and aortic devices were inflated (PAB + AO group), the pulmonary arterial band as for the PAB group and the aortic band adjusted to increase proximal systolic blood pressure by approximately 20 mm Hg. Effects on the functional performance were assessed 5 weeks after surgery by conductance catheters, followed by histologic and molecular assessment. Contractile performance was significantly improved in the PAB + AO group versus the PAB group for both ventricles. Relative to sham-operated animals, both banding groups showed significant differences in myocardial histologic and molecular responses. Relative to the PAB group, the PAB + AO group showed significantly decreased RV cardiomyocyte diameter, decreased RV collagen content, and reduced RV expression of endothelin receptor type B, matrix metalloproteinase 9, and transforming growth factor β genes. Aortic constriction in an experimental model of chronic RV pressure overload not only resulted in improved biventricular systolic function but also improved myocardial remodeling. These data suggest that chronically increased left ventricular afterload leads to a more physiologically hypertrophic response in the pressure-overloaded RV. Copyright © 2012 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

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.

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.

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. Specifically, no patient who was identified with constriction via cardiac magnetic resonance underwent inappropriate sternotomy. However, catheterization had substantial and unacceptable false-positive and false-negative rates with important clinical ramifications. Copyright © 2016 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

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.

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.

Discovery of novel small molecule inhibitors of cardiac hypertrophy using high throughput, high content imaging

PubMed Central

Reid, Brian G.; Stratton, Matthew S.; Bowers, Samantha; Cavasin, Maria A.; Demos-Davies, Kimberley M.; Susano, Isidro; McKinsey, Timothy A.

2016-01-01

Chronic cardiac hypertrophy is maladaptive and contributes to the pathogenesis of heart failure. The objective of this study was to identify small molecule inhibitors of pathological cardiomyocyte hypertrophy. High content screening was performed with primary neonatal rat ventricular myocytes (NRVMs) cultured on 96-well plates and treated with a library of 3241 distinct small molecules. Non-toxic hit compounds that blocked hypertrophy in response to phenylephrine (PE) and phorbol myristate acetate (PMA) were identified based on their ability to reduce cell size and inhibit expression of atrial natriuretic factor (ANF), which is a biomarker of pathological cardiac hypertrophy. Many of the hit compounds are existing drugs that have not previously been evaluated for benefit in the setting of cardiovascular disease. One such compound, the anti-malarial drug artesunate, blocked left ventricular hypertrophy (LVH) and improved cardiac function in adult mice subjected to transverse aortic constriction (TAC). These findings demonstrate that phenotypic screening with primary cardiomyocytes can be used to discover anti-hypertrophic lead compounds for heart failure drug discovery. Using annotated libraries of compounds with known selectivity profiles, this screening methodology also facilitates chemical biological dissection of signaling networks that control pathological growth of the heart. PMID:27130278

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

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.

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.

Modeling the Mechanics of Cell Division: Influence of Spontaneous Membrane Curvature, Surface Tension, and Osmotic Pressure

PubMed Central

Beltrán-Heredia, Elena; Almendro-Vedia, Víctor G.; Monroy, Francisco; Cao, Francisco J.

2017-01-01

Many cell division processes have been conserved throughout evolution and are being revealed by studies on model organisms such as bacteria, yeasts, and protozoa. Cellular membrane constriction is one of these processes, observed almost universally during cell division. It happens similarly in all organisms through a mechanical pathway synchronized with the sequence of cytokinetic events in the cell interior. Arguably, such a mechanical process is mastered by the coordinated action of a constriction machinery fueled by biochemical energy in conjunction with the passive mechanics of the cellular membrane. Independently of the details of the constriction engine, the membrane component responds against deformation by minimizing the elastic energy at every constriction state following a pathway still unknown. In this paper, we address a theoretical study of the mechanics of membrane constriction in a simplified model that describes a homogeneous membrane vesicle in the regime where mechanical work due to osmotic pressure, surface tension, and bending energy are comparable. We develop a general method to find approximate analytical expressions for the main descriptors of a symmetrically constricted vesicle. Analytical solutions are obtained by combining a perturbative expansion for small deformations with a variational approach that was previously demonstrated valid at the reference state of an initially spherical vesicle at isotonic conditions. The analytic approximate results are compared with the exact solution obtained from numerical computations, getting a good agreement for all the computed quantities (energy, area, volume, constriction force). We analyze the effects of the spontaneous curvature, the surface tension and the osmotic pressure in these quantities, focusing especially on the constriction force. The more favorable conditions for vesicle constriction are determined, obtaining that smaller constriction forces are required for positive spontaneous curvatures, low or negative membrane tension and hypertonic media. Conditions for spontaneous constriction at a given constriction force are also determined. The implications of these results for biological cell division are discussed. This work contributes to a better quantitative understanding of the mechanical pathway of cellular division, and could assist the design of artificial divisomes in vesicle-based self-actuated microsystems obtained from synthetic biology approaches. PMID:28579960

The Amniote Oculomotor Complex.

PubMed

Company, Verónica; Moreno-Bravo, Juan Antonio; Perez-Balaguer, Ariadna; Puelles, Eduardo

2018-04-16

The oculomotor (OM) complex is a combination of somatic and parasympatethic neurons. The correct development and wiring of this cranial pair is essential to perform basic functions: eyeball and eyelid movements, pupillary constriction, and lens accommodation. The improper formation or function of this nucleus leads pathologies such as strabismus. We describe the OM organization and function in different vertebrate brains, including chick, mouse, and human. The morphological localization is detailed, as well as the spatial relation with the trochlear nucleus in order to adjust some misleading anatomical topographic descriptions. We detailed the signaling processes needed for the specification of the OM neurons. The transcriptional programs driven the specification and differentiation of these neurons are partially determined. We summarized recent genetic studies that have led to the identification of guidance mechanisms involved in the migration, axon pathfinding, and targeting of the OM neurons. Finally, we overviewed the pathology associated to genetic malformations in the OM development and related clinical alterations. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc. © 2018 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-induced airway constriction. PMID:10188991

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.

Ameliorative potential of Vernonia cinerea on chronic constriction injury of sciatic nerve induced neuropathic pain in rats.

PubMed

Thiagarajan, Venkata R K; Shanmugam, Palanichamy; Krishnan, Uma M; Muthuraman, Arunachalam

2014-08-29

The aim of the present study is to investigate the ameliorative potential of ethanolic extract of whole plant of Vernonia cinerea in the chronic constriction injury (CCI) of sciatic nerve induced neuropathic pain in rats. Behavioral parameters such as a hot plate, acetone drop, paw pressure, Von Frey hair and tail immersion tests were performed to assess the degree of thermal, chemical and mechanical hyperalgesia and allodynia. Biochemical changes in sciatic nerve tissue were ruled out by estimating thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH) and total calcium levels. Ethanolic extract of Vernonia cinerea and pregabalin were administered for 14 consecutive days starting from the day of surgery. CCI of sciatic nerve has been shown to induce significant changes in behavioral, biochemical and histopathological assessments when compared to the sham control group. Vernonia cinerea attenuated in a dose dependent manner the above pathological changes induced by CCI of the sciatic nerve, which is similar to attenuation of the pregabalin pretreated group. The ameliorating effect of ethanolic extract of Vernonia cinerea against CCI of sciatic nerve induced neuropathic pain may be due to the presence of flavonoids and this effect is attributed to anti-oxidative, neuroprotective and calcium channel modulator actions of these compounds.

Ameliorative potential of Vernonia cinerea on chronic constriction injury of sciatic nerve induced neuropathic pain in rats.

PubMed

Thiagarajan, Venkata R K; Shanmugam, Palanichamy; Krishnan, Uma M; Muthuraman, Arunachalam

2014-09-01

The aim of the present study is to investigate the ameliorative potential of ethanolic extract of whole plant of Vernonia cinerea in the chronic constriction injury (CCI) of sciatic nerve induced neuropathic pain in rats. Behavioral parameters such as a hot plate, acetone drop, paw pressure, Von Frey hair and tail immersion tests were performed to assess the degree of thermal, chemical and mechanical hyperalgesia and allodynia. Biochemical changes in sciatic nerve tissue were ruled out by estimating thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH) and total calcium levels. Ethanolic extract of Vernonia cinerea and pregabalin were administered for 14 consecutive days starting from the day of surgery. CCI of sciatic nerve has been shown to induce significant changes in behavioral, biochemical and histopathological assessments when compared to the sham control group. Vernonia cinerea attenuated in a dose dependent manner the above pathological changes induced by CCI of the sciatic nerve, which is similar to attenuation of the pregabalin pretreated group. The ameliorating effect of ethanolic extract of Vernonia cinerea against CCI of sciatic nerve induced neuropathic pain may be due to the presence of flavonoids and this effect is attributed to anti-oxidative, neuroprotective and calcium channel modulator actions of these compounds.

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.

[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.

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.

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

The role of microtubules in contractile ring function.

PubMed

Conrad, A H; Paulsen, A Q; Conrad, G W

1992-05-01

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

The role of microtubules in contractile ring function

NASA Technical Reports Server (NTRS)

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

1992-01-01

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

Effect of hexylene glycol-altered microtubule distributions on cytokinesis and polar lobe formation in fertilized eggs of Ilyanassa obsoleta

NASA Technical Reports Server (NTRS)

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

1994-01-01

Some effects of gravity on early morphogenesis are correlated with microtubule locations within cells. During first cleavage in Ilyanassa obsoleta embryos, a transitory polar lobe constriction forms and then relaxes, allowing the polar lobe to merge with one daughter cell. If the polar lobe is equally divided or removed, morphogenesis is severely disrupted. To examine microtuble locations during early Ilyanassa development, eggs were fixed and stained for polymerized alpha-tubulin during first cleavage. The mitotic apparatus assembles at the animal pole. The cleavage furrow forms between the asters, constricting to a stabilized intercellular bridge encircling midbody-bound microtubules, whereas the polar lobe constriction forms below and parallel to the spindle, constricting to a transitory intercellular bridge encircling no detectable microtubules. At metaphase an alpha-tubulin epitope is distributed throughout the spindle, whereas a beta-tubulin epitope is present predominantly in the asters. Incubation in hexylene glycol, a drug that increases microtubule polymerization, during mitosis causes the polar lobe constriction to tighten around polymerized alpha-tubulin and remain stably constricted. If hexylene glycol is removed, alpha-tubulin staining disappears from the polar lobe constriction, which relaxes, whereas microtubules remain in the cleavage furrow, which remains constricted. These observations suggest that asymmetric distribution of microtubules affects early Ilyanassa cleavage patterns, and that continued presence of microtubules extending through an intercellular bridge is important for stabilization of the bridge constriction prior to completion of cytokinesis. These data provide the basis for further analysis of the role of microtubules in possible microgravity disruptions of Ilyanassa development.

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.

Nanowire structures and electrical devices

DOEpatents

Bezryadin, Alexey; Remeika, Mikas

2010-07-06

The present invention provides structures and devices comprising conductive segments and conductance constricting segments of a nanowire, such as metallic, superconducting or semiconducting nanowire. The present invention provides structures and devices comprising conductive nanowire segments and conductance constricting nanowire segments having accurately selected phases including crystalline and amorphous states, compositions, morphologies and physical dimensions, including selected cross sectional dimensions, shapes and lengths along the length of a nanowire. Further, the present invention provides methods of processing nanowires capable of patterning a nanowire to form a plurality of conductance constricting segments having selected positions along the length of a nanowire, including conductance constricting segments having reduced cross sectional dimensions and conductance constricting segments comprising one or more insulating materials such as metal oxides.

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.

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 indicates a strong agreement in effect profiles preclinical versus clinical, providing important translational validation for this widely used animal model. The present plasma brain natriuretic peptide biomarker findings support the measurement of plasma natriuretic peptides in the mouse transverse aortic constriction model to extend the translational utility of the model.

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 constriction model versus clinical use indicates a strong agreement in effect profiles preclinical versus clinical, providing important translational validation for this widely used animal model. The present plasma brain natriuretic peptide biomarker findings support the measurement of plasma natriuretic peptides in the mouse transverse aortic constriction model to extend the translational utility of the model. PMID:28491305

­Back-to-back mechanisms drive actomyosin ring closure during Drosophila embryo cleavage

PubMed Central

2016-01-01

Contraction of actomyosin rings during cytokinesis is typically attributed to actin filaments sliding toward each other via Myosin-2 motor activity. However, rings constrict in some cells in the absence of Myosin-2 activity. Thus, ring closure uses Myosin-2–dependent and –independent mechanisms. But what the Myosin-2–independent mechanisms are, and to what extent they are sufficient to drive closure, remains unclear. During cleavage in Drosophila melanogaster embryos, actomyosin rings constrict in two sequential and mechanistically distinct phases. We show that these phases differ in constriction speed and are genetically and pharmacologically separable. Further, Myosin-2 activity is required for slow constriction in “phase 1” but is largely dispensable for fast constriction in “phase 2,” and F-actin disassembly is only required for fast constriction in phase 2. Switching from phase 1 to phase 2 seemingly relies on the spatial organization of F-actin as controlled by Cofilin, Anillin, and Septin. Our work shows that fly embryos present a singular opportunity to compare separable ring constriction mechanisms, with varying Myosin-2 dependencies, in one cell type and in vivo. PMID:27799369

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.

Single-Stage Resection of Type II Constriction Rings in Limbs on the Basis of Histologic and Magnetic Resonance Imaging Observations: A Retrospective Study of 21 Consecutive Patients.

PubMed

Jiang, Yongkang; Mao, Hailei; Yang, Xi; Zhou, Shengbo; Ni, Feng; Xu, Qiming; Wang, Bin

2016-07-01

The purpose of this study was to determine the feasibility of single-stage resection for type II congenital constriction rings by means of histologic examination of resected specimens and imaging examination of affected extremities, and to evaluate the appearance and function of the extremities after single-stage surgery. The features of the skin on the constriction rings and the subcutaneous tissues were identified through continuous sectioning, hematoxylin and eosin staining, and immunohistologic staining of specimens of type II constriction rings obtained by means of surgery. The relationship between the constriction rings and the deep main blood vessels was evaluated using magnetic resonance imaging. Single-stage resection of the constriction band, reduction of the fascial flap, and triangular flap-plasty were performed for 21 patients. The appearance, lymphedema, and movement of the extremities were compared before and after the operation. Type II constriction rings in the extremities had normal full-layer skin structures. Collagen was found deposited densely at the base of the grooves, but the normal subcutaneous tissue space remained, and the vital nerves and blood vessels were unaffected. Complete resection of the constriction rings was achieved in all 21 patients, and lymphedema subsided 2 months after the operation. No episode of recurrence was found, and limb function was not affected at 26-month follow-up. Type II congenital constriction rings in limbs possess normal subcutaneous tissue spaces. A single-stage operation, which includes complete resection of the rings, fascial flap reduction, and triangular flap-plasty, could achieve a satisfactory appearance and good function. Therapeutic, III.

Safe emergency department removal of a hardened steel penile constriction ring.

PubMed

Peay, Jeremy; Smithson, James; Nelson, James; Witucki, Peter

2009-10-01

Penile constriction devices are used for the enhancement of sexual performance. These devices have the potential to become incarcerated, leading to necrosis and amputation if not removed promptly. This article presents a step-by-step approach for the safe removal of a hardened steel penile constriction device using somewhat unorthodox tools found in a hospital. We present a case of an incarcerated hardened steel penile constriction ring that was not able to be removed with conventional techniques. We describe a novel technique using an electric grinder and laryngoscope blade. The technique described in this article is a valuable and relatively safe technique for the Emergency Physician to facilitate the timely removal of a hardened steel constriction device.

Robust gap repair in the contractile ring ensures timely completion of cytokinesis

PubMed Central

Maiato, Helder; Pinto, Inês Mendes; Rubinstein, Boris

2016-01-01

Cytokinesis in animal cells requires the constriction of an actomyosin contractile ring, whose architecture and mechanism remain poorly understood. We use laser microsurgery to explore the biophysical properties of constricting rings in Caenorhabditis elegans embryos. Laser cutting causes rings to snap open. However, instead of disintegrating, ring topology recovers and constriction proceeds. In response to severing, a finite gap forms and is repaired by recruitment of new material in an actin polymerization–dependent manner. An open ring is able to constrict, and rings repair from successive cuts. After gap repair, an increase in constriction velocity allows cytokinesis to complete at the same time as controls. Our analysis demonstrates that tension in the ring increases while net cortical tension at the site of ingression decreases throughout constriction and suggests that cytokinesis is accomplished by contractile modules that assemble and contract autonomously, enabling local repair of the actomyosin network. Consequently, cytokinesis is a highly robust process impervious to discontinuities in contractile ring structure. PMID:27974482

Myosin concentration underlies cell size–dependent scalability of actomyosin ring constriction

PubMed Central

Wright, Graham D.; Leong, Fong Yew; Chiam, Keng-Hwee; Chen, Yinxiao; Jedd, Gregory; Balasubramanian, Mohan K.

2011-01-01

In eukaryotes, cytokinesis is accomplished by an actomyosin-based contractile ring. Although in Caenorhabditis elegans embryos larger cells divide at a faster rate than smaller cells, it remains unknown whether a similar mode of scalability operates in other cells. We investigated cytokinesis in the filamentous fungus Neurospora crassa, which exhibits a wide range of hyphal circumferences. We found that N. crassa cells divide using an actomyosin ring and larger rings constricted faster than smaller rings. However, unlike in C. elegans, the total amount of myosin remained constant throughout constriction, and there was a size-dependent increase in the starting concentration of myosin in the ring. We predict that the increased number of ring-associated myosin motors in larger rings leads to the increased constriction rate. Accordingly, reduction or inhibition of ring-associated myosin slows down the rate of constriction. Because the mechanical characteristics of contractile rings are conserved, we predict that these findings will be relevant to actomyosin ring constriction in other cell types. PMID:22123864

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.

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

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).

Nitric oxide as an initiator of brain lesions during the development of Alzheimer disease.

PubMed

Aliev, Gjumrakch; Palacios, Hector H; Lipsitt, Amanda E; Fischbach, Kathryn; Lamb, Bruce T; Obrenovich, Mark E; Morales, Ludis; Gasimov, Eldar; Bragin, Valentin

2009-10-01

Nitric oxide (NO) is an important regulatory molecule for the host defense that plays a fundamental role in the cardiovascular, immune, and nervous systems. NO is synthesized through the conversion of L-arginine to L-citrulline by the enzyme NO synthase (NOS), which is found in three isoforms classified as neuronal (nNOS), inducible (iNOS), and endothelial (eNOS). Recent evidence supports the theory that this bioactive molecule has an influential role in the disruption of normal brain and vascular homeostasis, a condition known to elucidate chronic hypoperfusion which ultimately causes the development of brain lesions and the pathology that typify Alzheimer disease (AD). In addition, vascular NO activity appears to be a major contributor to this pathology before any overexpression of NOS isoforms is observed in the neuron, glia, and microglia of the brain tree, where the overexpression the NOS isoforms causes the formation of a large amount of NO. We hypothesize that since an imbalance between the NOS isoforms and endothelin-1 (ET-1), a human gene that encodes for blood vessel constriction, can cause antioxidant system insufficiency; by using pharmacological intervention with NO donors and/or NO suppressors, the brain lesions and the downstream progression of brain pathology and dementia in AD should be delayed or minimized.

Platelet-activating factor dilates efferent arterioles through glomerulus-derived nitric oxide.

PubMed

Arima, S; Ren, Y; Juncos, L A; Ito, S

1996-01-01

Despite evidence that platelet-activating factor (PAF) is produced by the glomerulus, its direct action on the glomerular microcirculation is poorly understood. It was recently reported that at picomolar concentrations, PAF dilates isolated microperfused afferent arterioles (Af-Art) via nitric oxide (NO). The present study tested the hypothesis that PAF acts on the glomerulus to release NO, which in turn controls the resistance of the efferent arteriole (Ef-Art). Rabbit Ef-Art were perfused from the distal end (retrograde perfusion [RP]) to eliminate the influence of the glomerulus, or through the glomerulus from the end of the Af-Art (orthograde perfusion [OP]) to maintain the influence of the glomerulus. Ef-Art were preconstricted by approximately 40% with norepinephrine and increasing doses of PAF were added to both the arteriolar perfusate and bath. Only with OP did PAF at picomolar concentrations cause significant dilation: at 400 pmol, the diameter increased by 64 +/- 11% from the preconstricted level (N = 6, P < 0.01). This dilation was completely abolished by pretreatment with an NO-synthesis inhibitor. To study its possible constrictor action, PAF was added to nonpreconstricted Ef-Art. At nanomolar concentrations, PAF constricted Ef-Art similarly in both RP and OP: at 40 nM, the diameter decreased by 24 +/- 4% (N = 6, P < 0.01) and 20 +/- 2% (N = 6, P < 0.01), respectively. This constriction was attenuated by pretreatment with indomethacin (Indo) in both RP (14 +/- 2%, N = 7; P < 0.02 versus without Indo) and OP (10 +/- 2%, N = 6; P < 0.02 versus without Indo). (1) at picomolar concentrations, PAF stimulates the glomerulus to release NO, which in turn dilates the Ef-Art; and (2) at nanomolar concentrations, PAF constricts the Ef-Art partly through release of cyclooxygenase metabolites. Thus, PAF may play a role in glomerular hemodynamics under various physiological and pathological conditions.

A Microfluidic Technique to Probe Cell Deformability

PubMed Central

Hoelzle, David J.; Varghese, Bino A.; Chan, Clara K.; Rowat, Amy C.

2014-01-01

Here we detail the design, fabrication, and use of a microfluidic device to evaluate the deformability of a large number of individual cells in an efficient manner. Typically, data for ~102 cells can be acquired within a 1 hr experiment. An automated image analysis program enables efficient post-experiment analysis of image data, enabling processing to be complete within a few hours. Our device geometry is unique in that cells must deform through a series of micron-scale constrictions, thereby enabling the initial deformation and time-dependent relaxation of individual cells to be assayed. The applicability of this method to human promyelocytic leukemia (HL-60) cells is demonstrated. Driving cells to deform through micron-scale constrictions using pressure-driven flow, we observe that human promyelocytic (HL-60) cells momentarily occlude the first constriction for a median time of 9.3 msec before passaging more quickly through the subsequent constrictions with a median transit time of 4.0 msec per constriction. By contrast, all-trans retinoic acid-treated (neutrophil-type) HL-60 cells occlude the first constriction for only 4.3 msec before passaging through the subsequent constrictions with a median transit time of 3.3 msec. This method can provide insight into the viscoelastic nature of cells, and ultimately reveal the molecular origins of this behavior. PMID:25226269

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.

Rate and topography of peptidoglycan synthesis during cell division in Escherichia coli: Concept of a leading edge

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

Wientjes, F.B.; Nanninga, N.

1989-06-01

The rate at which the peptidoglycan of Escherichia coli is synthesized during the division cycle was studied with two methods. One method involved synchronization of E. coli MC4100 lysA cultures by centrifugal elutriation and subsequent pulse-labeling of the synchronously growing cultures with (meso-{sup 3}H)diaminopimelic acid (({sup 3}H)Dap). The second method was autoradiography of cells pulse-labeled with ({sup 3}H)Dap. It was found that the peptidoglycan is synthesized at a more or less exponentially increasing rate during the division cycle with a slight acceleration in this rate as the cells start to constrict. Apparently, polar cap formation requires synthesis of extra surfacemore » components, presumably to accommodate for a change in the surface-to-volume ratio. Furthermore, it was found that the pool size of Dap was constant during the division cycle. Close analysis of the topography of ({sup 3}H)Dap incorporation at the constriction site revealed that constriction proceeded by synthesis of peptidoglycan at the leading edge of the invaginating cell envelope. During constriction, no reallocation of incorporation occurred, i.e., the incorporation at the leading edge remained high throughout the process of constriction. Impairment of penicillin-binding protein 3 by mutation or by the specific {beta}-lactam antibiotic furazlocillin did not affect ({sup 3}H)Dap incorporation during initiation of constriction. However, the incorporation at the constriction site was inhibited in later stages of the constriction process. It is concluded that during division at least two peptidoglycan-synthesizing systems are operating sequentially.« less

MR findings of Minamata disease--organic mercury poisoning.

PubMed

Korogi, Y; Takahashi, M; Okajima, T; Eto, K

1998-01-01

We describe MR findings in patients with Minamata disease who have been followed for a long time. All patients examined were affected after daily eating of a large quantity of methylmercury-contaminated seafood, from 1955 to 1958, and showed typical neurological findings. On MR images, the visual cortex, the cerebellar vermis and hemispheres, and the postcentral cortex are significantly atrophic in Minamata disease. The visual cortex is slightly hypointense on T1-weighted images and hyperintense on T2-weighted images, probably representing the pathologic changes of status spongiosus. MRI can demonstrate the lesions located in the calcarine area, cerebellum, and postcentral gyri, which are probably related to three of the characteristic manifestations of this disease: the constriction of the visual fields, ataxia, and sensory disturbance, respectively.

Cytochrome c oxidase subunit 4 isoform 2-knockout mice show reduced enzyme activity, airway hyporeactivity, and lung pathology

PubMed Central

Hüttemann, Maik; Lee, Icksoo; Gao, Xiufeng; Pecina, Petr; Pecinova, Alena; Liu, Jenney; Aras, Siddhesh; Sommer, Natascha; Sanderson, Thomas H.; Tost, Monica; Neff, Frauke; Aguilar-Pimentel, Juan Antonio; Becker, Lore; Naton, Beatrix; Rathkolb, Birgit; Rozman, Jan; Favor, Jack; Hans, Wolfgang; Prehn, Cornelia; Puk, Oliver; Schrewe, Anja; Sun, Minxuan; Höfler, Heinz; Adamski, Jerzy; Bekeredjian, Raffi; Graw, Jochen; Adler, Thure; Busch, Dirk H.; Klingenspor, Martin; Klopstock, Thomas; Ollert, Markus; Wolf, Eckhard; Fuchs, Helmut; Gailus-Durner, Valérie; Hrabě de Angelis, Martin; Weissmann, Norbert; Doan, Jeffrey W.; Bassett, David J. P.; Grossman, Lawrence I.

2012-01-01

Cytochrome c oxidase (COX) is the terminal enzyme of the mitochondrial electron transport chain. The purpose of this study was to analyze the function of lung-specific cytochrome c oxidase subunit 4 isoform 2 (COX4i2) in vitro and in COX4i2-knockout mice in vivo. COX was isolated from cow lung and liver as control and functionally analyzed. COX4i2-knockout mice were generated and the effect of the gene knockout was determined, including COX activity, tissue energy levels, noninvasive and invasive lung function, and lung pathology. These studies were complemented by a comprehensive functional screen performed at the German Mouse Clinic (Neuherberg, Germany). We show that isolated cow lung COX containing COX4i2 is about twice as active (88 and 102% increased activity in the presence of allosteric activator ADP and inhibitor ATP, respectively) as liver COX, which lacks COX4i2. In COX4i2-knockout mice, lung COX activity and cellular ATP levels were significantly reduced (−50 and −29%, respectively). Knockout mice showed decreased airway responsiveness (60% reduced Penh and 58% reduced airway resistance upon challenge with 25 and 100 mg methacholine, respectively), and they developed a lung pathology deteriorating with age that included the appearance of Charcot-Leyden crystals. In addition, there was an interesting sex-specific phenotype, in which the knockout females showed reduced lean mass (−12%), reduced total oxygen consumption rate (−8%), improved glucose tolerance, and reduced grip force (−14%) compared to wild-type females. Our data suggest that high activity lung COX is a central determinant of airway function and is required for maximal airway responsiveness and healthy lung function. Since airway constriction requires energy, we propose a model in which reduced tissue ATP levels explain protection from airway hyperresponsiveness, i.e., absence of COX4i2 leads to reduced lung COX activity and ATP levels, which results in impaired airway constriction and thus reduced airway responsiveness; long-term lung pathology develops in the knockout mice due to impairment of energy-costly lung maintenance processes; and therefore, we propose mitochondrial oxidative phosphorylation as a novel target for the treatment of respiratory diseases, such as asthma.—Hüttemann, M., Lee, I., Gao, X., Pecina, P., Pecinova, A., Liu, J., Aras, S., Sommer, N., Sanderson, T. H., Tost, M., Neff, F., Aguilar-Pimentel, J. A., Becker, L., Naton, B., Rathkolb, B., Rozman, J., Favor, J., Hans, W., Prehn, C., Puk, O., Schrewe, A., Sun, M., Höfler, H., Adamski, J., Bekeredjian, R., Graw, J., Adler, T., Busch, D. H., Klingenspor, M., Klopstock, T., Ollert, M., Wolf, E., Fuchs, H., Gailus-Durner, V., Hrabě de Angelis, M., Weissmann, N., Doan, J. W., Bassett, D. J. P., Grossman, L. I. Cytochrome c oxidase subunit 4 isoform 2-knockout mice show reduced enzyme activity, airway hyporeactivity, and lung pathology. PMID:22730437

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.

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

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.

Retained placenta: will medical treatment ever be possible?

PubMed

Akol, Achier D; Weeks, Andrew D

2016-05-01

The standard treatment for retained placenta is manual removal whatever its subtype (adherens, trapped or partial accreta). Although medical treatment should reduce the risk of anesthetic and surgical complications, they have not been found to be effective. This may be due to the contrasting uterotonic needs of the different underlying pathologies. In placenta adherens, oxytocics have been used to contract the retro-placental myometrium. However, if injected locally through the umbilical vein, they bypass the myometrium and perfuse directly into the venous system. Intravenous injection is an alternative but exacerbates a trapped placenta. Conversely, for trapped placentas, a relaxant could help by resolving cervical constriction, but would worsen the situation for placenta adherens. This confusion over medical treatment will continue unless we can find a way to diagnose the underlying pathology. This will allow us to stop treating the retained placenta as a single entity and to deliver targeted treatments. © 2016 The Authors. Acta Obstetricia et Gynecologica Scandinavica published by John Wiley & Sons Ltd on behalf of Nordic Federation of Societies of Obstetrics and Gynecology (NFOG).

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. Furthermore, this experimental work will inform subsequent numerical modeling of flow and field-based measurements at Locke Island.

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.

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.

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

Crucial role of rho-kinase in pressure overload-induced right ventricular hypertrophy and dysfunction in mice.

PubMed

Ikeda, Shohei; Satoh, Kimio; Kikuchi, Nobuhiro; Miyata, Satoshi; Suzuki, Kota; Omura, Junichi; Shimizu, Toru; Kobayashi, Kenta; Kobayashi, Kazuto; Fukumoto, Yoshihiro; Sakata, Yasuhiko; Shimokawa, Hiroaki

2014-06-01

Right ventricular (RV) failure is the leading cause of death in various cardiopulmonary diseases, including pulmonary hypertension. It is generally considered that the RV is vulnerable to pressure overload as compared with the left ventricle (LV). However, as compared with LV failure, the molecular mechanisms of RV failure are poorly understood, and hence therapeutic targets of the disorder remain to be elucidated. Thus, we aimed to identify molecular therapeutic targets for RV failure in a mouse model of pressure overload. To induce pressure overload to respective ventricles, we performed pulmonary artery constriction or transverse aortic constriction in mice. We first performed microarray analysis and found that the molecules related to RhoA/Rho-kinase and integrin pathways were significantly upregulated in the RV with pulmonary artery constriction compared with the LV with transverse aortic constriction. Then, we examined the responses of both ventricles to chronic pressure overload in vivo. We demonstrated that compared with transverse aortic constriction, pulmonary artery constriction caused greater extents of mortality, Rho-kinase expression (especially ROCK2 isoform), and oxidative stress in pressure-overloaded RV, reflecting the weakness of the RV in response to pressure overload. Furthermore, mice with myocardial-specific overexpression of dominant-negative Rho-kinase showed resistance to pressure overload-induced hypertrophy and dysfunction associated with reduced oxidative stress. Finally, dominant-negative Rho-kinase mice showed a significantly improved long-term survival in both pulmonary artery constriction and transverse aortic constriction as compared with littermate controls. These results indicate that the Rho-kinase pathway plays a crucial role in RV hypertrophy and dysfunction, suggesting that the pathway is a novel therapeutic target of RV failure in humans. © 2014 American Heart Association, Inc.

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

Flow Energy Piezoelectric Bimorph Nozzle Harvester

NASA Technical Reports Server (NTRS)

Walkemeyer, Phillip E. (Inventor); Tosi, Phillipe (Inventor); Corbett, Thomas Gary (Inventor); Hall, Jeffrey L. (Inventor); Lee, Hyeong Jae (Inventor); Arrazola, Alvaro Jose (Inventor); Sherrit, Stewart (Inventor); Colonius, Tim (Inventor); Kim, Namhyo (Inventor); Sun, Kai (Inventor)

2016-01-01

A flow energy harvesting device having a harvester pipe includes a flow inlet that receives flow from a primary pipe, a flow outlet that returns the flow into the primary pipe, and a flow diverter within the harvester pipe having an inlet section coupled to the flow inlet, a flow constriction section coupled to the inlet section and positioned at a midpoint of the harvester pipe and having a spline shape with a substantially reduced flow opening size at a constriction point along the spline shape, and an outlet section coupled to the constriction section. The harvester pipe may further include a piezoelectric structure extending from the inlet section through the constriction section and point such that the fluid flow past the constriction point results in oscillatory pressure amplitude inducing vibrations in the piezoelectric structure sufficient to cause a direct piezoelectric effect and to generate electrical power for harvesting.

[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.

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 .

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.

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.

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.

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 cyclooxygenase-derived prostaglandins (indomethacin, 10 μM) affected myogenic constriction. Sensitivity of mesenteric arteries to angiotensin II (10 nM – 100 μM) was increased (P<0.05) in CHF (pD2 7.1±0.4) compared to SHAM (pD2 6.2±0.3), while the sensitivity to KCl and phenylephrine was not different. Our results demonstrate increased myogenic constriction in small mesenteric arteries of rats with CHF, potentially making it an important target for therapy in counteracting increased vascular resistance in CHF. Our results further suggest active and instantaneous participation of AT1-receptors in increased myogenic constriction in CHF, involving increased sensitivity of AT1-receptors rather than apparent ACE-mediated local angiotensin II production. PMID:12890711

Scour at bridge sites in Delaware, Maryland, and Virginia

USGS Publications Warehouse

Hayes, Donald C.

1996-01-01

Scour data were obtained from discharge measure- ments to develop and evaluate the reliability of constriction-scour and local-scour equations for rivers in Delaware, Maryland, and Virginia. No independent constriction-scour or local-scour equations were developed from the data because no significant relation was deter-mined between measured scour and streamflow, streambed, and bridge characteristics. Two existing equations were evaluated for prediction of constriction scour and 14 existing equations were evaluated for prediction of local scour. Constriction-scour data were obtained from historical stream discharge measurements, field surveys, and bridge plans at nine bridge sites in the three-State area. Constriction scour was computed by subtracting the average-streambed elevation in the constricted reach from an uncontracted-channel reference elevation. Hydraulic conditions were estimated for the measurements with the greatest discharges by use of the Water-Surface Profile computation model. Measured and calculated constriction-scour data were used to evaluate the reliability of Laursen's clear-water constriction-scour equation and Laursen's live-bed constriction-scour equation. Laursen's clear-water constriction-scour equation underestimated 21 of 23 scour measure- ments made at three sites. A sensitivity analysis showed that the equation is extremely sensitive to estimates of the channel-bottom width. Reduction in estimates of bottom width by one-third resulted in predictions of constriction scour slightly greater than measured values for all scour measurements. Laursen's live-bed constriction- scour equation underestimated 10 of 14 scour measurements made at one site. The error between measured and predicted constriction scour was less than 1.0 ft (feet) for 12 measure-ments and less than 0.5 ft for 8 measurements. Local-scour data were obtained from stream discharge measurements, field surveys, and bridge plans at 15 bridge sites in the three-State area. The reliability of 14 local-scour equations were evaluated. From visual inspection of the plotted data, the Colorado State University, Froehlich design, Laursen, and Mississippi pier-scour equations appeared to be the best predictors of local scour. The Colorado State University equation underestimated 11 scour depths in clear-water scour conditions by a maximum of 2.4 ft, and underestimated 3 scour depth in live-bed scour conditions by a maximum of 1.3 ft. The Froehlich design equation under- estimated two scour depth in clear-water scour conditions by a maximum of 1.2 ft, and under- estimated one scour depth in live-bed scour conditions by a maximum of 0.4 ft. Laursen's equation overestimated the maximum scour depth in clear-water scour conditions by approximately one-half pier width or approximately 1.5 ft, and overestimated the maximum scour depth in live-bed scour conditions by approximately one-pier width or approximately 3 ft. The Mississippi equation underestimated six scour depths in clear-water scour conditions by a maximum of 1.2 ft, and underestimated one scour depth in live-bed scour conditions by 1.6 ft. In both clear-water and live-bed scour conditions, the upper limit for the depth of scour to pier-width ratio for all local scour measurements was 2.1. An accurate pier- approach velocity is necessary to use many local pier-scour equations for bridge design. Velocity data from all the discharge measurements reviewed for this investigation were used to develop a design curve to estimate pier-approach velocity from mean cross-sectional velocity. A least- squares regression and offset were used to envelop the velocity data.

Ex Vivo Artifacts and Histopathologic Pitfalls in the Lung.

PubMed

Thunnissen, Erik; Blaauwgeers, Hans J L G; de Cuba, Erienne M V; Yick, Ching Yong; Flieder, Douglas B

2016-03-01

Surgical and pathologic handling of lung physically affects lung tissue. This leads to artifacts that alter the morphologic appearance of pulmonary parenchyma. To describe and illustrate mechanisms of ex vivo artifacts that may lead to diagnostic pitfalls. In this study 4 mechanisms of ex vivo artifacts and corresponding diagnostic pitfalls are described and illustrated. The 4 patterns of artifacts are: (1) surgical collapse, due to the removal of air and blood from pulmonary resections; (2) ex vivo contraction of bronchial and bronchiolar smooth muscle; (3) clamping edema of open lung biopsies; and (4) spreading of tissue fragments and individual cells through a knife surface. Morphologic pitfalls include diagnostic patterns of adenocarcinoma, asthma, constrictive bronchiolitis, and lymphedema. Four patterns of pulmonary ex vivo artifacts are important to recognize in order to avoid morphologic misinterpretations.

MR findings in seven patients with organic mercury poisoning (Minamata disease).

PubMed

Korogi, Y; Takahashi, M; Shinzato, J; Okajima, T

1994-09-01

To study the long-term MR findings in seven patients with Minamata disease. All patients examined were affected after eating daily considerable amounts of the methylmercury-contaminated seafoods from 1955 through 1958 and showed typical neurologic findings. T1- and T2-weighted images were obtained in axial, coronal, and sagittal sections. The visual cortex, the cerebellar vermis and hemispheres, and the postcentral cortex were significantly atrophic. The visual cortex was slightly hypointense on T1-weighted images and hyperintense on T2-weighted images, probably representing the pathologic changes of status spongiosus. MR demonstrated the lesions, located in the calcarine area, cerebellum, and postcentral gyri, which are probably related to three of the characteristic manifestations of this disease: the constriction of the visual fields, ataxia, and sensory disturbance, respectively.

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

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.

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

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.

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 ...

Flow cytometry analysis of inflammatory cells isolated from the sciatic nerve and DRG after chronic constriction injury in mice.

PubMed

Liu, Liping; Yin, Yan; Li, Fei; Malhotra, Charvi; Cheng, Jianguo

2017-06-01

Cellular responses to nerve injury play a central role in the pathogenesis of neuropathic pain. However, the analysis of site specific cellular responses to nerve injury and neuropathic pain is limited to immunohistochemistry staining with numerous limitations. We proposed to apply flow cytometry to overcome some of the limitations and developed two protocols for isolation of cells from small specimens of the sciatic nerve and dorsal root ganglion (DRG) in mice. RESULTS AND COMPARASION WITH EXISTING: methods We found that both the non-enzymatic and enzymatic approaches were highly effective in harvesting a sufficient number of cells for flow cytometry analysis in normal and pathological conditions. The total number of cells in the injury site of the sciatic and its DRGs increased significantly 14days after chronic constriction injury (CCI) of the sciatic nerve, compared to sham surgery control or the contralateral control. The enzymatic approach yielded a significantly higher total number of cells and CD45 negative cells, suggesting that this approach allows for harvest of more resident cells, compared to the non-enzymatic method. The percentage of CD45 + /CD11b + cells was significantly increased in the sciatic nerve but not in the DRG. These results were consistent with both protocols. We thus offer two simple and effective protocols that allow for application of flow cytometry to the investigation of cellular and molecular mechanisms of neuropathic pain. Copyright © 2017 Elsevier B.V. All rights reserved.

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

PubMed

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

2016-02-01

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

βIII Spectrin Is Necessary for Formation of the Constricted Neck of Dendritic Spines and Regulation of Synaptic Activity in Neurons.

PubMed

Efimova, Nadia; Korobova, Farida; Stankewich, Michael C; Moberly, Andrew H; Stolz, Donna B; Wang, Junling; Kashina, Anna; Ma, Minghong; Svitkina, Tatyana

2017-07-05

Dendritic spines are postsynaptic structures in neurons often having a mushroom-like shape. Physiological significance and cytoskeletal mechanisms that maintain this shape are poorly understood. The spectrin-based membrane skeleton maintains the biconcave shape of erythrocytes, but whether spectrins also determine the shape of nonerythroid cells is less clear. We show that βIII spectrin in hippocampal and cortical neurons from rodent embryos of both sexes is distributed throughout the somatodendritic compartment but is particularly enriched in the neck and base of dendritic spines and largely absent from spine heads. Electron microscopy revealed that βIII spectrin forms a detergent-resistant cytoskeletal network at these sites. Knockdown of βIII spectrin results in a significant decrease in the density of dendritic spines. Surprisingly, the density of presynaptic terminals is not affected by βIII spectrin knockdown. However, instead of making normal spiny synapses, the presynaptic structures in βIII spectrin-depleted neurons make shaft synapses that exhibit increased amplitudes of miniature EPSCs indicative of excessive postsynaptic excitation. Thus, βIII spectrin is necessary for formation of the constricted shape of the spine neck, which in turn controls communication between the synapse and the parent dendrite to prevent excessive excitation. Notably, mutations of SPTNB2 encoding βIII spectrin are associated with neurodegenerative syndromes, spinocerebellar ataxia Type 5, and spectrin-associated autosomal recessive cerebellar ataxia Type 1, but molecular mechanisms linking βIII spectrin functions to neuronal pathologies remain unresolved. Our data suggest that spinocerebellar ataxia Type 5 and spectrin-associated autosomal recessive cerebellar ataxia Type 1 pathology likely arises from poorly controlled synaptic activity that leads to excitotoxicity and neurodegeneration. SIGNIFICANCE STATEMENT Dendritic spines are small protrusions from neuronal dendrites that make synapses with axons of other neurons in the brain. Dendritic spines usually have a mushroom-like shape, which is essential for brain functions, because aberrant spine morphology is associated with many neuropsychiatric disorders. The bulbous head of a mushroom-shaped spine makes the synapse, whereas the narrow neck transmits the incoming signals to the dendrite and supposedly controls the signal propagation. We show that a cytoskeletal protein βIII spectrin plays a key role for the formation of narrow spine necks. In the absence of βIII spectrin, dendritic spines collapse onto dendrites. As a result, synaptic strength exceeds acceptable levels and damages neurons, explaining pathology of human syndromes caused by βIII spectrin mutations. Copyright © 2017 the authors 0270-6474/17/376443-18$15.00/0.

βIII Spectrin Is Necessary for Formation of the Constricted Neck of Dendritic Spines and Regulation of Synaptic Activity in Neurons

PubMed Central

Efimova, Nadia; Korobova, Farida; Moberly, Andrew H.; Stolz, Donna B.; Wang, Junling; Kashina, Anna; Ma, Minghong

2017-01-01

Dendritic spines are postsynaptic structures in neurons often having a mushroom-like shape. Physiological significance and cytoskeletal mechanisms that maintain this shape are poorly understood. The spectrin-based membrane skeleton maintains the biconcave shape of erythrocytes, but whether spectrins also determine the shape of nonerythroid cells is less clear. We show that βIII spectrin in hippocampal and cortical neurons from rodent embryos of both sexes is distributed throughout the somatodendritic compartment but is particularly enriched in the neck and base of dendritic spines and largely absent from spine heads. Electron microscopy revealed that βIII spectrin forms a detergent-resistant cytoskeletal network at these sites. Knockdown of βIII spectrin results in a significant decrease in the density of dendritic spines. Surprisingly, the density of presynaptic terminals is not affected by βIII spectrin knockdown. However, instead of making normal spiny synapses, the presynaptic structures in βIII spectrin-depleted neurons make shaft synapses that exhibit increased amplitudes of miniature EPSCs indicative of excessive postsynaptic excitation. Thus, βIII spectrin is necessary for formation of the constricted shape of the spine neck, which in turn controls communication between the synapse and the parent dendrite to prevent excessive excitation. Notably, mutations of SPTNB2 encoding βIII spectrin are associated with neurodegenerative syndromes, spinocerebellar ataxia Type 5, and spectrin-associated autosomal recessive cerebellar ataxia Type 1, but molecular mechanisms linking βIII spectrin functions to neuronal pathologies remain unresolved. Our data suggest that spinocerebellar ataxia Type 5 and spectrin-associated autosomal recessive cerebellar ataxia Type 1 pathology likely arises from poorly controlled synaptic activity that leads to excitotoxicity and neurodegeneration. SIGNIFICANCE STATEMENT Dendritic spines are small protrusions from neuronal dendrites that make synapses with axons of other neurons in the brain. Dendritic spines usually have a mushroom-like shape, which is essential for brain functions, because aberrant spine morphology is associated with many neuropsychiatric disorders. The bulbous head of a mushroom-shaped spine makes the synapse, whereas the narrow neck transmits the incoming signals to the dendrite and supposedly controls the signal propagation. We show that a cytoskeletal protein βIII spectrin plays a key role for the formation of narrow spine necks. In the absence of βIII spectrin, dendritic spines collapse onto dendrites. As a result, synaptic strength exceeds acceptable levels and damages neurons, explaining pathology of human syndromes caused by βIII spectrin mutations. PMID:28576936

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.

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

Can breathing-like pressure oscillations reverse or prevent narrowing of small intact airways?

PubMed

Harvey, Brian C; Parameswaran, Harikrishnan; Lutchen, Kenneth R

2015-07-01

Periodic length fluctuations of airway smooth muscle during breathing are thought to modulate airway responsiveness in vivo. Recent animal and human intact airway studies have shown that pressure fluctuations simulating breathing can only marginally reverse airway narrowing and are ineffective at protecting against future narrowing. However, these previous studies were performed on relatively large (>5 mm diameter) airways, which are inherently stiffer than smaller airways for which a preponderance of airway constriction in asthma likely occurs. The goal of this study was to determine the effectiveness of breathing-like transmural pressure oscillations to reverse induced narrowing and/or protect against future narrowing of smaller, more compliant intact airways. We constricted smaller (luminal diameter = 2.92 ± 0.29 mm) intact airway segments twice with ACh (10(-6) M), once while applying tidal-like pressure oscillations (5-15 cmH2O) before, during, and after inducing constriction (Pre + Post) and again while only imposing the tidal-like pressure oscillation after induced constriction (Post Only). Smaller airways were 128% more compliant than previously studied larger airways. This increased compliance translated into 196% more strain and 76% greater recovery (41 vs. 23%) because of tidal-like pressure oscillations. Larger pressure oscillations (5-25 cmH2O) caused more recovery (77.5 ± 16.5%). However, pressure oscillations applied before and during constriction resulted in the same steady-state diameter as when pressure oscillations were only applied after constriction. These data show that reduced straining of the airways before a challenge likely does not contribute to the emergence of airway hyperreactivity observed in asthma but may serve to sustain a given level of constriction. Copyright © 2015 the American Physiological Society.

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

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 Elsevier Inc. All rights reserved.

The crosstalk between autonomic nervous system and blood vessels

PubMed Central

Sheng, Yulan; Zhu, Li

2018-01-01

The autonomic nervous system (ANS), comprised of two primary branches, sympathetic and parasympathetic nervous system, plays an essential role in the regulation of vascular wall contractility and tension. The sympathetic and parasympathetic nerves work together to balance the functions of autonomic effector organs. The neurotransmitters released from the varicosities in the ANS can regulate the vascular tone. Norepinephrine (NE), adenosine triphosphate (ATP) and Neuropeptide Y (NPY) function as vasoconstrictors, whereas acetylcholine (Ach) and calcitonin gene-related peptide (CGRP) can mediate vasodilation. On the other hand, vascular factors, such as endothelium-derived relaxing factor nitric oxide (NO), and constriction factor endothelin, play an important role in the autonomic nervous system in physiologic conditions. Endothelial dysfunction and inflammation are associated with the sympathetic nerve activity in the pathological conditions, such as hypertension, heart failure, and diabetes mellitus. The dysfunction of the autonomic nervous system could be a risk factor for vascular diseases and the overactive sympathetic nerve is detrimental to the blood vessel. In this review, we summarize findings concerning the crosstalk between ANS and blood vessels in both physiological and pathological conditions and hope to provide insight into the development of therapeutic interventions of vascular diseases. PMID:29593847

BET Acetyl-Lysine Binding Proteins Control Pathological Cardiac Hypertrophy

PubMed Central

Spiltoir, Jessica I.; Stratton, Matthew S.; Cavasin, Maria A.; Demos-Davies, Kim; Reid, Brian G.; Qi, Jun; Bradner, James E.; McKinsey, Timothy A.

2014-01-01

Cardiac hypertrophy is an independent predictor of adverse outcomes in patients with heart failure, and thus represents an attractive target for novel therapeutic intervention. JQ1, a small molecule inhibitor of bromodomain and extraterminal (BET) acetyl-lysine reader proteins, was identified in a high throughput screen designed to discover novel small molecule regulators of cardiomyocyte hypertrophy. JQ1 dose-dependently blocked agonist-dependent hypertrophy of cultured neonatal rat ventricular myocytes (NRVMs) and reversed the prototypical gene program associated with pathological cardiac hypertrophy. JQ1 also blocked left ventricular hypertrophy (LVH) and improved cardiac function in adult mice subjected to transverse aortic constriction (TAC). The BET family consists of BRD2, BRD3, BRD4 and BRDT. BRD4 protein expression was increased during cardiac hypertrophy, and hypertrophic stimuli promoted recruitment of BRD4 to the transcriptional start site (TSS) of the gene encoding atrial natriuretic factor (ANF). Binding of BRD4 to the ANF TSS was associated with increased phosphorylation of local RNA polymerase II. These findings define a novel function for BET proteins as signal-responsive regulators of cardiac hypertrophy, and suggest that small molecule inhibitors of these epigenetic reader proteins have potential as therapeutics for heart failure. PMID:23939492

Cardiac-specific overexpression of aldehyde dehydrogenase 2 exacerbates cardiac remodeling in response to pressure overload.

PubMed

Dassanayaka, Sujith; Zheng, Yuting; Gibb, Andrew A; Cummins, Timothy D; McNally, Lindsey A; Brittian, Kenneth R; Jagatheesan, Ganapathy; Audam, Timothy N; Long, Bethany W; Brainard, Robert E; Jones, Steven P; Hill, Bradford G

2018-06-01

Pathological cardiac remodeling during heart failure is associated with higher levels of lipid peroxidation products and lower abundance of several aldehyde detoxification enzymes, including aldehyde dehydrogenase 2 (ALDH2). An emerging idea that could explain these findings concerns the role of electrophilic species in redox signaling, which may be important for adaptive responses to stress or injury. The purpose of this study was to determine whether genetically increasing ALDH2 activity affects pressure overload-induced cardiac dysfunction. Mice subjected to transverse aortic constriction (TAC) for 12 weeks developed myocardial hypertrophy and cardiac dysfunction, which were associated with diminished ALDH2 expression and activity. Cardiac-specific expression of the human ALDH2 gene in mice augmented myocardial ALDH2 activity but did not improve cardiac function in response to pressure overload. After 12 weeks of TAC, ALDH2 transgenic mice had larger hearts than their wild-type littermates and lower capillary density. These findings show that overexpression of ALDH2 augments the hypertrophic response to pressure overload and imply that downregulation of ALDH2 may be an adaptive response to certain forms of cardiac pathology. Copyright © 2018. Published by Elsevier B.V.

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.

Annual Research Progress Report Fiscal Year 1987. Volume 1,

DTIC Science & Technology

1987-10-01

Constrictive Pericarditis 86 in Patients. (0) C-20-85 Pressure Waveforms and Reflections in the Human Aorta: Compari- 87 son of a Cadaver Model with In...in Constrictive 125 Pericarditis . (0) C-60-86 The Natural History of HTLV-III Infection and Disease in a 126 United States Military Population. (0...Sheet Date: 18 Mar 87 Proj No: C-16-85 Status: Terminated Title: Significance of Post Radiotherapy Constrictive Pericarditis in Patients. Start Date 21

Timely Endocytosis of Cytokinetic Enzymes Prevents Premature Spindle Breakage during Mitotic Exit

PubMed Central

Onishi, Masayuki; Yeong, Foong May

2016-01-01

Cytokinesis requires the spatio-temporal coordination of membrane deposition and primary septum (PS) formation at the division site to drive acto-myosin ring (AMR) constriction. It has been demonstrated that AMR constriction invariably occurs only after the mitotic spindle disassembly. It has also been established that Chitin Synthase II (Chs2p) neck localization precedes mitotic spindle disassembly during mitotic exit. As AMR constriction depends upon PS formation, the question arises as to how chitin deposition is regulated so as to prevent premature AMR constriction and mitotic spindle breakage. In this study, we propose that cells regulate the coordination between spindle disassembly and AMR constriction via timely endocytosis of cytokinetic enzymes, Chs2p, Chs3p, and Fks1p. Inhibition of endocytosis leads to over accumulation of cytokinetic enzymes during mitotic exit, which accelerates the constriction of the AMR, and causes spindle breakage that eventually could contribute to monopolar spindle formation in the subsequent round of cell division. Intriguingly, the mitotic spindle breakage observed in endocytosis mutants can be rescued either by deleting or inhibiting the activities of, CHS2, CHS3 and FKS1, which are involved in septum formation. The findings from our study highlight the importance of timely endocytosis of cytokinetic enzymes at the division site in safeguarding mitotic spindle integrity during mitotic exit. PMID:27447488

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

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

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

Jung, Yong-Woon; Mascagni, Michael, E-mail: Mascagni@fsu.edu

2014-09-28

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

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.

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

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.

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

[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.

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

Constriction band syndrome occurring in the setting of in vitro fertilization and advanced maternal age

PubMed Central

Rinker, Brian; Vasconez, Henry C

2006-01-01

The debate as to the pathogenesis of constriction band syndrome began with Hippocrates and continues today. The exogenous theory attributes the condition to entanglement of the fetus in the amniotic remnants following premature rupture of the amnion, which is in contrast to the endogenous, or genetic, mechanism. A case of constriction band syndrome in the setting of in vitro fertilization, where the child was genetically unrelated to the birth mother, is presented. Constriction band syndrome has been reported following amniocentesis and chorionic villus sampling, but it has not heretofore been presented in the setting of in vitro fertilization. In addition, the present case presents an opportunity to separate maternal from genetic factors and, possibly, shed some light on the etiology of the condition. PMID:19554231

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.

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?

Functional vision loss: a diagnosis of exclusion.

PubMed

Villegas, Rex B; Ilsen, Pauline F

2007-10-01

Most cases of visual acuity or visual field loss can be attributed to ocular pathology or ocular manifestations of systemic pathology. They can also occasionally be attributed to nonpathologic processes or malingering. Functional vision loss is any decrease in vision the origin of which cannot be attributed to a pathologic or structural abnormality. Two cases of functional vision loss are described. In the first, a 58-year-old man presented for a baseline eye examination for enrollment in a vision rehabilitation program. He reported bilateral blindness since a motor vehicle accident with head trauma 4 years prior. Entering visual acuity was "no light perception" in each eye. Ocular health examination was normal and the patient made frequent eye contact with the examiners. He was referred for neuroimaging and electrophysiologic testing. The second case was a 49-year-old man who presented with a long history of intermittent monocular diplopia. His medical history was significant for psycho-medical evaluations and a diagnosis of factitious disorder. Entering uncorrected visual acuities were 20/20 in each eye, but visual field testing found constriction. No abnormalities were found that could account for the monocular diplopia or visual field deficit. A diagnosis of functional vision loss secondary to factitious disorder was made. Functional vision loss is a diagnosis of exclusion. In the event of reduced vision in the context of a normal ocular health examination, all other pathology must be ruled out before making the diagnosis of functional vision loss. Evaluation must include auxiliary ophthalmologic testing, neuroimaging of the visual pathway, review of the medical history and lifestyle, and psychiatric evaluation. Comanagement with a psychiatrist is essential for patients with functional vision loss.

[THE PHYSICAL CHEMICAL, BIOLOGICAL BASICS OF CELLS ABSORPTION OF UNESTERIFIED FATTY ACIDS; ALBUMIN, CAVEOLIN, CLATHRIN AND LIPID-BINDING PROTEINS OF CYTOPLASM (THE LECTURE)].

PubMed

Titov, V N; Shoibonov, B B

2016-03-01

From aposition of phylogenetic theory of general pathology, obesity and metabolic syndrome are pathology of fatty cells. However, the first is a pathology of phylogenetically early visceral fatty cells of omentum. They supply with substratum of energy realization of biologic function of trophology, homeostasis, endoecology and adaptation. The visceral fatty cells of omentum have no receptors to insulin and synthesize adaptively insulin and they are not characterized by biologic reaction of proliferation. The obesity is a pathology of late in phylogenesis subcutaneous adpocytes. They are insulin-dependent and supply with substratum of energy realization of one biologic function of locomotion--movement at the expense of constriction of cross-striated miocytes. The adipocytes in terms of adaptation synthesize humoral mediator adponectin and actively implement biologic function of proliferation. Under both aphysiologic conditions increases passive by gradient of concentration, absorption by cells albumin-unbound free fatty acids in unionized form in micellae's composition. The passive aphysiologic absorption of free fatty acids by cells which under intracellular compartmentalization don't oxidize mitochondria results in synthesis, accumulation of triglycerides in cytoplasm of cells which don't implement it physiologically. The aphysiologic absorption of free fatty acids by cells, their etherification in triglyceride, in particular, in phylogenetically late β-cells of islets and either late cardiomyocytes which fatty acids don't synthesize de novo results in development of aphysiologic processes and disorder of function. From position of biology, these cells in vivo are subjected to loss similar to apoptosis. The formation of corpuscles of apoptosis compromise biologic function of endoecology activating biologic reaction of inflammation.

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.

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.

Experimental and numerical investigation of the sound generation mechanisms of sibilant fricatives using a simplified vocal tract model

NASA Astrophysics Data System (ADS)

Yoshinaga, Tsukasa; Nozaki, Kazunori; Wada, Shigeo

2018-03-01

The sound generation mechanisms of sibilant fricatives were investigated with experimental measurements and large-eddy simulations using a simplified vocal tract model. The vocal tract geometry was simplified to a three-dimensional rectangular channel, and differences in the geometries while pronouncing fricatives /s/ and /∫/ were expressed by shifting the position of the tongue and its constricted flow channel. Experimental results showed that the characteristic peak frequency of the fricatives decreased when the distance between the tongue and teeth increased. Numerical simulations revealed that the jet flow generated from the constriction impinged on the upper teeth wall and caused the main sound source upstream and downstream from the gap between the teeth. While magnitudes of the sound source decreased with increments of the frequency, amplitudes of the pressure downstream from the constriction increased at the peak frequencies of the corresponding tongue position. These results indicate that the sound pressures at the peak frequencies increased by acoustic resonance in the channel downstream from the constriction, and the different frequency characteristics between /s/ and /∫/ were produced by changing the constriction and the acoustic node positions inside the vocal tract.

Frostbite in an adolescent football player: a case report.

PubMed

Rivlin, Michael; King, Marnie; Kruse, Richard; Ilyas, Asif M

2014-01-01

To present the case of vascular compromise of a finger from a confluent circumferential blister due to an inappropriately applied commercial cold pack in a high school athlete and to describe the mechanism of iatrogenic injury, acute surgical management, rehabilitation, and pathophysiology of frostbite and constriction injuries. A 17-year-old male football player presented with a frostbite and constriction injury to the index finger secondary to prolonged use of a cooling pack after a mild traumatic injury to the digit. He developed a prolonged sensory deficit from thermal injury, as well as acute vascular compromise requiring urgent operative intervention. Frostbite and constriction injury to the index finger. Emergency surgical decompression and occupational therapy. Frostbite injuries can occur iatrogenically because of inappropriate use of cooling devices or gel packs. Fingers are commonly injured extremities that are particularly susceptible to frostbite and compression injuries. To our knowledge, no case of vascular compromise from the blister constriction of digits has been reported. Patients and their caregivers must be educated about how to properly use cooling devices. Clinicians need to fully evaluate patients with iatrogenic frostbite injuries, giving particular attention to neurovascular status, and must recognize the need for surgical release of constriction syndrome to prevent substantial morbidity.

Modelling responses of the inert-gas washout and MRI to bronchoconstriction.

PubMed

Foy, Brody H; Kay, David; Bordas, Rafel

2017-01-01

Many lung diseases lead to an increase in ventilation heterogeneity (VH). Two clinical practices for the measurement of patient VH are in vivo imaging, and the inert gas multiple breath washout (MBW). In this study computational modelling was used to compare the responses of MBW indices LCI and s cond and MRI measured global and local ventilation indices, σ r and σ local , to constriction of airways in the conducting zone of the lungs. The simulations show that s cond , LCI and σ r behave quite similarly to each other, all being sensitive to increases in the severity of constriction, while exhibiting little sensitivity to the depth at which constriction occurs. In contrast, the local MRI index σ local shows strong sensitivity to depth of constriction, but lowered sensitivity to constriction severity. We finish with an analysis of the sensitivity of MRI indices to grid sizes, showing that results should be interpreted with reference to the image resolution. Overall we conclude that the application of both local and global VH measures may help to classify different types of bronchoconstriction. Copyright © 2016 Elsevier B.V. All rights reserved.

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.

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.

Chronic calcific constrictive pericarditis complicating Churg-Strauss syndrome: first reported case.

PubMed

Aboukhoudir, Falah; Pansieri, Michel; Rekik, Sofiene

2014-10-01

Churg-Strauss syndrome is a necrotizing systemic vasculitis characterized by extravascular granulomas and eosinophilic infiltrates of small vessels. Although cardiac complications are considered to be relatively common, no case of constrictive calcified pericarditis has ever been previously described in this setting. In this report, we present the case of a 46-year-old man with Churg-Strauss syndrome, in whom we were able to document the development of symptomatic calcific constrictive pericarditis during a 10-year period despite long-term corticosteroid therapy. Georg Thieme Verlag KG Stuttgart · New York.

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…

Vascular and parenchymal amyloid pathology in an Alzheimer disease knock-in mouse model: interplay with cerebral blood flow.

PubMed

Li, Hongmei; Guo, Qinxi; Inoue, Taeko; Polito, Vinicia A; Tabuchi, Katsuhiko; Hammer, Robert E; Pautler, Robia G; Taffet, George E; Zheng, Hui

2014-08-09

Accumulation and deposition of β-amyloid peptides (Aβ) in the brain is a central event in the pathogenesis of Alzheimer's disease (AD). Besides the parenchymal pathology, Aβ is known to undergo active transport across the blood-brain barrier and cerebral amyloid angiopathy (CAA) is a prominent feature in the majority of AD. Although impaired cerebral blood flow (CBF) has been implicated in faulty Aβ transport and clearance, and cerebral hypoperfusion can exist in the pre-clinical phase of Alzheimer's disease (AD), it is still unclear whether it is one of the causal factors for AD pathogenesis, or an early consequence of a multi-factor condition that would lead to AD at late stage. To study the potential interaction between faulty CBF and amyloid accumulation in clinical-relevant situation, we generated a new amyloid precursor protein (APP) knock-in allele that expresses humanized Aβ and a Dutch mutation in addition to Swedish/London mutations and compared this line with an equivalent knock-in line but in the absence of the Dutch mutation, both crossed onto the PS1M146V knock-in background. Introduction of the Dutch mutation results in robust CAA and parenchymal Aβ pathology, age-dependent reduction of spatial learning and memory deficits, and CBF reduction as detected by fMRI. Direct manipulation of CBF by transverse aortic constriction surgery on the left common carotid artery caused differential changes in CBF in the anterior and middle region of the cortex, where it is reduced on the left side and increased on the right side. However these perturbations in CBF resulted in the same effect: both significantly exacerbate CAA and amyloid pathology. Our study reveals a direct and positive link between vascular and parenchymal Aβ; both can be modulated by CBF. The new APP knock-in mouse model recapitulates many symptoms of AD including progressive vascular and parenchymal Aβ pathology and behavioral deficits in the absence of APP overexpression.

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 response to acute ductal constriction. PMID:20363848

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.

Enhanced magnetocaloric effect material

DOEpatents

Lewis, Laura J. H.

2006-07-18

A magnetocaloric effect heterostructure having a core layer of a magnetostructural material with a giant magnetocaloric effect having a magnetic transition temperature equal to or greater than 150 K, and a constricting material layer coated on at least one surface of the magnetocaloric material core layer. The constricting material layer may enhance the magnetocaloric effect by restriction of volume changes of the core layer during application of a magnetic field to the heterostructure. A magnetocaloric effect heterostructure powder comprising a plurality of core particles of a magnetostructural material with a giant magnetocaloric effect having a magnetic transition temperature equal to or greater than 150 K, wherein each of the core particles is encapsulated within a coating of a constricting material is also disclosed. A method for enhancing the magnetocaloric effect within a giant magnetocaloric material including the step of coating a surface of the magnetocaloric material with a constricting material is disclosed.

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)

Hyperenhancement of the Pericardium on Cardiac Magnetic Resonance Imaging: A Marker of Acute Inflammation and Neovascularization or a Chronic Fibrotic State.

PubMed

Mullen, Liam; Chew, Pei Gee; Frost, Frederick; Ahmed, Ayesha; Khand, Aleem

2016-01-01

In cardiac magnetic resonance imaging, hyperenhancement of the pericardium post gadolinium administration in acute chest pain often signifies pericarditis with an acute inflammatory response and neovascularization. In the context of constrictive pericarditis, case series have indicated that the intensity of hyperenhancement and the thickness of the pericardium imply reversibility of the physiology of the constrictive pericarditis. We present a case of intense hyperenhancement and marked thickening of the pericardium in a patient with constrictive pericarditis with antecedent chest pain. Surgical resection of the pericardium and microscopy revealed a chronic fibrotic state with no evidence of inflammation or neovascularization, thus clarifying the failure of initial medical/anti-inflammatory treatment. Our case highlights the fact that hyperenhancement of the pericardium post gadolinium is non-specific for histology and does not necessarily imply the reversibility of pericardial constriction. © 2016 S. Karger AG, Basel.

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.

Fabricated autologous epidermal cell sheets for the prevention of esophageal stricture after circumferential ESD in a porcine model.

PubMed

Kanai, Nobuo; Yamato, Masayuki; Ohki, Takeshi; Yamamoto, Masakazu; Okano, Teruo

2012-10-01

Endoscopic submucosal dissection (ESD) is an accepted treatment for early esophageal carcinoma. However, resection of a large mucosal area, as with circumferential ESD, induces severe stricture formation. To evaluate the efficacy of cultured autologous epidermal cell sheets to prevent severe esophageal constriction after circumferential ESD. Animal study. University institute. Eight pigs underwent circumferential esophageal ESD while under general anesthesia. In 4 pigs, fabricated autologous epidermal cell sheets were endoscopically transplanted to the central ESD sites immediately after the ESD. The other 4 pigs underwent circumferential ESD only. Necropsy and histological assessment were performed at 1 and 2 weeks post-ESD. Weight gain, degree of mucosal constriction, and histological assessments. All pigs in the control group showed severe esophageal constriction after 2 weeks. The control and transplanted groups had weight gains of -10.3% and 0.3% (P = .03), respectively, and the mean degrees of constriction were 88% and 56% (P < .01), respectively. Early re-epithelialization and mild fibrosis in the muscularis were observed in the transplanted group. Animal study, small sample size. Fabricated autologous skin epidermal cell sheets would be useful in preventing severe esophageal constriction after circumferential ESD. Copyright © 2012 American Society for Gastrointestinal Endoscopy. Published by Mosby, Inc. All rights reserved.

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.

Periodontitis and myocardial hypertrophy.

PubMed

Suzuki, Jun-Ichi; Sato, Hiroki; Kaneko, Makoto; Yoshida, Asuka; Aoyama, Norio; Akimoto, Shouta; Wakayama, Kouji; Kumagai, Hidetoshi; Ikeda, Yuichi; Akazawa, Hiroshi; Izumi, Yuichi; Isobe, Mitsuaki; Komuro, Issei

2017-04-01

There is a deep relationship between cardiovascular disease and periodontitis. It has been reported that myocardial hypertrophy may be affected by periodontitis in clinical settings. Although these clinical observations had some study limitations, they strongly suggest a direct association between severity of periodontitis and left ventricular hypertrophy. However, the detailed mechanisms between myocardial hypertrophy and periodontitis have not yet been elucidated. Recently, we demonstrated that periodontal bacteria infection is closely related to myocardial hypertrophy. In murine transverse aortic constriction models, a periodontal pathogen, Aggregatibacter actinomycetemcomitans markedly enhanced cardiac hypertrophy with matrix metalloproteinase-2 activation, while another pathogen Porphyromonas gingivalis (P.g.) did not accelerate these pathological changes. In the isoproterenol-induced myocardial hypertrophy model, P.g. induced myocardial hypertrophy through Toll-like receptor-2 signaling. From our results and other reports, regulation of chronic inflammation induced by periodontitis may have a key role in the treatment of myocardial hypertrophy. In this article, we review the pathophysiological mechanism between myocardial hypertrophy and periodontitis.

A rational model for maximizing the effects of therapeutic relationship regulation in personality disorders with poor metacognition and over-regulation of affects.

PubMed

Dimaggio, Giancarlo; Carcione, Antonino; Salvatore, Giampaolo; Semerari, Antonio; Nicolò, Giuseppe

2010-11-01

The therapeutic relationship plays a key role in personality disorder (PD) psychotherapy. Some aspects of therapeutic relationship regulation appear important for treatment of PD clients, including those with constricted relational schemas, poor metacognition, and over-regulation of affects described here. AIM.: To propose a rational model for how and when to work on the therapeutic relationship by treating the underlying personality pathology. Formalize a step-by-step procedure for performing operations such as validation of clients' experiences, creating a sense of sharedness, assessing the quality of the therapeutic relationship in order to prevent and repair ruptures in the alliance, self-disclosing by the therapist, and metacommunication on the basis of clients' responses to treatment. We discuss the implications of this model for further research into the PD therapy process. 2010 The British Psychological Society.

Vascular Effects of Endothelin Receptor Antagonists Depends on Their Selectivity for ETA Versus ETB Receptors and on the Functionality of Endothelial ETB Receptors.

PubMed

Iglarz, Marc; Steiner, Pauline; Wanner, Daniel; Rey, Markus; Hess, Patrick; Clozel, Martine

2015-10-01

The goal of this study was to characterize the role of Endothelin (ET) type B receptors (ETB) on vascular function in healthy and diseased conditions and demonstrate how it affects the pharmacological activity of ET receptor antagonists (ERAs). The contribution of the ETB receptor to vascular relaxation or constriction was characterized in isolated arteries from healthy and diseased rats with systemic (Dahl-S) or pulmonary hypertension (monocrotaline). Because the role of ETB receptors is different in pathological vis-à-vis normal conditions, we compared the efficacy of ETA-selective and dual ETA/ETB ERAs on blood pressure in hypertensive rats equipped with telemetry. In healthy vessels, ETB receptors stimulation with sarafotoxin S6c induced vasorelaxation and no vasoconstriction. In contrast, in arteries of rats with systemic or pulmonary hypertension, endothelial ETB-mediated relaxation was lost while vasoconstriction on stimulation by sarafotoxin S6c was observed. In hypertensive rats, administration of the dual ETA/ETB ERA macitentan on top of a maximal effective dose of the ETA-selective ERA ambrisentan further reduced blood pressure, indicating that ETB receptors blockade provides additional benefit. Taken together, these data suggest that in pathology, dual ETA/ETB receptor antagonism can provide superior vascular effects compared with ETA-selective receptor blockade.

Effects of a water extract of Lepidium meyenii root in different models of persistent pain in rats.

PubMed

Tenci, Barbara; Di Cesare Mannelli, Lorenzo; Maresca, Mario; Micheli, Laura; Pieraccini, Giuseppe; Mulinacci, Nadia; Ghelardini, Carla

2017-10-26

Lepidium meyenii (Walp.), commonly called maca, is an Andean crop belonging to the Brassicaceae family. Maca hypocotils are habitually consumed as customary food as well as traditional remedies for pathological conditions such as infertility. Moreover, the characterization of maca extracts revealed the presence of compounds that are able to modulate the nervous system. Aimed to evaluate the efficacy of L. meyenii in persistent pain, the present study analyzed the effects of a commercial root extract from maca in different animal models reproducing the most common causes of chronic painful pathologies. A qualitative characterization of this commercial extract by high performance liquid chromatography-mass spectrometry and tandem mass spectrometry analyses allowed us to confirm the presence of some macamides known as bioactive constituents of this root and the absence of the main aromatic glucosinolates. The acute oral administration of maca extract is able to reduce mechanical hypersensitivity and postural unbalance induced by the intra-articular injection of monoiodoacetate and the chronic-constriction injury of the sciatic nerve. Furthermore, L. meyenii extract reverts pain threshold alterations evoked by oxaliplatin and paclitaxel. A good safety profile in mice and rats was shown. In conclusion, the present maca extract could be considered as a therapeutic opportunity to relieve articular and neuropathic pain.

Caveolin 3-dependent loss of t-tubular ICa during hypertrophy and heart failure in mice.

PubMed

Bryant, Simon M; Kong, Cherrie H T; Watson, Judy J; Gadeberg, Hanne C; James, Andrew F; Cannell, Mark B; Orchard, Clive H

2018-05-01

What is the central question of this study? Heart failure is associated with redistribution of L-type Ca 2+ current (I Ca ) away from the t-tubule membrane to the surface membrane of cardiac ventricular myocytes. However, the underlying mechanism and its dependence on severity of pathology (hypertrophy versus failure) are unclear. What is the main finding and its importance? Increasing severity of response to transverse aortic constriction, from hypertrophy to failure, was accompanied by graded loss of t-tubular I Ca and loss of regulation of I Ca by caveolin 3. Thus, the pathological loss of t-tubular I Ca , which contributes to impaired excitation-contraction coupling and thereby cardiac function in vivo, appears to be attributable to loss of caveolin 3-dependent stimulation of t-tubular I Ca . Previous work has shown redistribution of L-type Ca 2+ current (I Ca ) from the t-tubules to the surface membrane of rat ventricular myocytes after myocardial infarction. However, whether this occurs in all species and in response to other insults, the relationship of this redistribution to the severity of the pathology, and the underlying mechanism, are unknown. We have therefore investigated the response of mouse hearts and myocytes to pressure overload induced by transverse aortic constriction (TAC). Male C57BL/6 mice underwent TAC or equivalent sham operation 8 weeks before use. I Ca and Ca 2+ transients were measured in isolated myocytes, and expression of caveolin 3 (Cav3), junctophilin 2 (Jph2) and bridging integrator 1 (Bin1) was determined. C3SD peptide was used to disrupt Cav3 binding to its protein partners. Some animals showed cardiac hypertrophy in response to TAC with little evidence of heart failure, whereas others showed greater hypertrophy and pulmonary congestion. These graded changes were accompanied by graded cellular hypertrophy, t-tubule disruption, decreased expression of Jph2 and Cav3, and decreased t-tubular I Ca density, with no change at the cell surface, and graded impairment of Ca 2+ release at t-tubules. C3SD decreased I Ca density in control but not in TAC myocytes. These data suggest that the graded changes in cardiac function and size that occur in response to TAC are paralleled by graded changes in cell structure and function, which will contribute to the impaired function observed in vivo. They also suggest that loss of t-tubular I Ca is attributable to loss of Cav3-dependent stimulation of I Ca . © 2018 The Authors. Experimental Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.

Superoxide differentially controls pulmonary and systemic vascular tone through multiple signalling pathways

PubMed Central

Snetkov, Vladimir A.; Smirnov, Sergey V.; Kua, Justin; Aaronson, Philip I.; Ward, Jeremy P.T.; Knock, Greg A.

2011-01-01

Aims The aim of this study was to determine the relative importance of Ca2+ sensitization, ion channels, and intracellular Ca2+ ([Ca2+]i) in the mixed constrictor/relaxation actions of superoxide anion on systemic and pulmonary arteries. Methods and results Pulmonary and mesenteric arteries were obtained from rat. Superoxide was generated in arteries and cells with 6-anilino-5,8-quinolinequinone (LY83583). Following pre-constriction with U46619, 10 μmol/L LY83583 caused constriction in pulmonary and relaxation in mesenteric arteries. Both constrictor and relaxant actions of LY83583 were inhibited by superoxide dismutase and catalase. LY83583 caused Rho-kinase-dependent constriction in α-toxin-permeabilized pulmonary but not mesenteric arteries. Phosphorylation of myosin phosphatase-targeting subunit-1 (MYPT-1; as determined by western blot), was enhanced by LY83583 in pulmonary artery only. However, in both artery types, changes in tension were closely correlated with changes in phosphorylation of the 20 kDa myosin light chain as well as changes in [Ca2+]i (as measured with Fura PE-3), with LY83583 causing increases in pulmonary and decreases in mesenteric arteries. When U46619 was replaced by 30 mmol/L K+, all changes in [Ca2+]i were abolished and LY83583 constricted both artery types. The KV channel inhibitor 4-aminopyridine abolished the LY83583-induced relaxation in mesenteric artery without affecting constriction in pulmonary artery. However, LY83583 caused a similar hyperpolarizing shift in the steady-state activation of KV current in isolated smooth muscle cells of both artery types. Conclusions Superoxide only causes Rho-kinase-dependent Ca2+ sensitization in pulmonary artery, resulting in constriction, and whilst it opens KV channels in both artery types, this only results in relaxation in mesenteric. PMID:20805095

Evaluation of hawthorn extract on immunomodulatory biomarkers in a pressure overload model of heart failure.

PubMed

Bleske, Barry E; Zineh, Issam; Hwang, Hyun Seok; Welder, Gregory J; Ghannam, Michael M J; Boluyt, Marvin O

2007-12-01

Hawthorn extract (Crataegeus sp.) a botanical complementary and alternative medicine is often used to treat heart failure. The mechanism(s) by which hawthorn extract may treat heart failure is unknown but may include, theoretically, immunological effects. Therefore, the purpose of this study is to determine the effect of hawthorn extract on the immunomodulatory response in a pressure overload model of heart failure. A total of 62 male Sprague-Dawley rats were randomized to either aortic constriction + vehicle (AC; n=15), aortic constriction + hawthorn 1.3 mg/kg (HL, n=17), aortic constriction + hawthorn 13 mg/kg (HM, n=15), or aortic constriction + hawthorn 130 mg/kg (HH, n=15). Six months after surgical procedure animals were sacrificed and plasma samples obtained for the measurement of the following immunomodulatory markers: interleukin (IL) IL-1ss, IL-2, IL-6, IL-10; and leptin. The mortality rate following 6 months of aortic constriction was 40% in the AC group compared to 41%, 60%, and 53% for the HL, HM, and HH groups respectively (P>0.05 compared to AC). Aortic constriction produced a similar increase in the left ventricle/body weight ratio for all groups. Hawthorn extract had no effect on the immunomodulatory markers measured in this study, although there appeared to be a trend suggesting suppression of IL-2 plasma concentrations. In this animal model of heart failure, hawthorn extract failed to significantly affect the immunomodulatory response characterized after 6 months of pressure overload at a time when approximately 50% mortality was exhibited. Mechanisms other than immunological may better define hawthorn's effect in treating heart failure.

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.

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.

Design and Development of Variable-Load Energy Absorbers

DTIC Science & Technology

1981-06-16

Three concepts were developed and/or tested: a wire - bending mechanism, a tube-constricting mechanism, and a hydraulic energy absorber. Preliminary full...scale working models of the wire - bending mechanism and the tube-constricting mechanisms were built and tested. The hydraulic energy absorber was

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.

Eddies in a bottleneck: an arbitrary Debye length theory for capillary electroosmosis.

PubMed

Park, Stella Y; Russo, Christopher J; Branton, Daniel; Stone, Howard A

2006-05-15

Using an applied electrical field to drive fluid flows becomes desirable as channels become smaller. Although most discussions of electroosmosis treat the case of thin Debye layers, here electroosmotic flow (EOF) through a constricted cylinder is presented for arbitrary Debye lengths (kappa(-1)) using a long wavelength perturbation of the cylinder radius. The analysis uses the approximation of small potentials. The varying diameter of the cylinder produces radially and axially varying effective electric fields, as well as an induced pressure gradient. We predict the existence of eddies for certain constricted geometries and propose the possibility of electrokinetic trapping in these regions. We also present a leading-order criterion which predicts central eddies in very narrow constrictions at the scale of the Debye length. Eddies can be found both in the center of the channel and along the perimeter, and the presence of the eddies is a consequence of the induced pressure gradient that accompanies electrically driven flow into a narrow constriction.

Eddies in a Bottleneck: An Arbitrary Debye Length Theory for Capillary Electroosmosis

PubMed Central

Park, Stella Y.; Russo, Christopher J.; Branton, Daniel; Stone, Howard A.

2011-01-01

Using an applied electrical field to drive fluid flows becomes desirable as channels become smaller. Although most discussions of electroosmosis treat the case of thin Debye layers, here electroosmotic flow (EOF) through a constricted cylinder is presented for arbitrary Debye lengths (κ−1) using a long wavelength perturbation of the cylinder radius. The analysis uses the approximation of small potentials. The varying diameter of the cylinder produces radially and axially varying effective electric fields, as well as an induced pressure gradient. We predict the existence of eddies for certain constricted geometries and propose the possibility of electrokinetic trapping in these regions. We also present a leading-order criterion which predicts central eddies in very narrow constrictions at the scale of the Debye length. Eddies can be found both in the center of the channel and along the perimeter, and the presence of the eddies is a consequence of the induced pressure gradient that accompanies electrically driven flow into a narrow constriction. PMID:16376361

The 1983 hydraulic jump in Crystal Rapid: implications for river- running and geomorphic evolution in the Grand Canyon.

USGS Publications Warehouse

Kieffer, S.W.

1985-01-01

At Crystal Creek, a debris fan was emplaced in 1966, constricting the channel of the Colorado River to about 0.25 of its upstream width between 1967 and 1983, forming a major rapid. The hydraulics of Crystal Creek rapid are described, and an analysis is presented to support the hypothesis that the major wave in the rapid was a normal wave (one type of hydraulic jump). Hydraulic jumps rarely occur in natural river channels with erodible beds, but one was present at Crystal Rapid because of the unusually severe constriction of the Colorado River by the 1966 debris fan. A quantitative model for river debris fan shapes is proposed and is used to estimate prehistoric flood levels from the observed constrictions: the 0.5 value of river constriction found at the more mature debris fans in the Grand Canyon suggests that peak flood discharges of approximately 11 320 m3/s have occurred. -from Author

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.

Microfluidic model experiments on the injectability of monoclonal antibody solutions

NASA Astrophysics Data System (ADS)

Duchene, Charles; Filipe, Vasco; Nakach, Mostafa; Huille, Sylvain; Lindner, Anke

2017-11-01

Autoinjection devices that allow patients to self-administer medicine are becoming used more frequently; however, this advance comes with an increased need for precision in the injection process. The rare occurrence of protein aggregates in solutions of monoclonal antibodies constitutes a threat to the reliability of such devices. Here we study the flow of protein solutions containing aggregates in microfluidic model systems, mimicking injection devices, to gain fundamental understanding of the catastrophic clogging of constrictions of given size. We form aggregates by mechanically shaking or heating antibody solutions and then inject these solutions into microfluidic channels with varying types of constrictions. Geometrical clogging occurs when aggregates reach the size of the constriction and can in some cases be undone by increasing the applied pressure. We perform systematic experiments varying the relative aggregate size and the flow rate or applied pressure. The mechanical deformation of aggregates during their passage through constrictions is investigated to gain a better understanding of the clogging and unclogging mechanisms.

[Impact of introduction of O2 on the welding arc of gas pool coupled activating TIG].

PubMed

Huang, Yong; Wang, Yan-Lei; Zhang, Zhi-Guo

2014-05-01

In the present paper, Boltzmann plot method was applied to analyze the temperature distributions of the are plasma when the gas pool coupled activating TIG welding was at different coupling degrees with the outer gas being O2. Based on this study of temperature distributions, the changing regularities of are voltage and are appearance were studied. The result shows that compared with traditional TIG welding, the introduction of O2 makes the welding arc constricted slightly, the temperature of the are center build up, and the are voltage increase. When argon being the inner gas, oxygen serving as the outer gas instead of argon makes the are constricted more obviously. When the coupling degree increases from 0 to 2, the temperature of the are center and the are voltage both increase slightly. In the gas pool coupled activating TIG welding the are is constricted not obviously, and the reason why the weld penetration is improved dramatically in the welding of stainless steel is not are constriction.

Physiological activation of Akt by PHLPP1 deletion protects against pathological hypertrophy.

PubMed

Moc, Courtney; Taylor, Amy E; Chesini, Gino P; Zambrano, Cristina M; Barlow, Melissa S; Zhang, Xiaoxue; Gustafsson, Åsa B; Purcell, Nicole H

2015-02-01

To examine the role of physiological Akt signalling in pathological hypertrophy through analysis of PHLPP1 (PH domain leucine-rich repeat protein phosphatase) knock-out (KO) mice. To investigate the in vivo requirement for 'physiological' control of Akt activation in cardiac growth, we examined the effect of deleting the Akt phosphatase, PHLPP, on the induction of cardiac hypertrophy. Basal Akt phosphorylation increased nearly two-fold in the cardiomyocytes from PHLPP1 KO mice and physiological hypertrophy induced by swimming exercise was accentuated as assessed by increased heart size and myocyte cell area. In contrast, the development of pathophysiological hypertrophy induced by pressure overload and assessed by increases in heart size, myocyte cell area, and hypertrophic gene expression was attenuated. This attenuation coincided with decreased fibrosis and cell death in the KO mice. Cast moulding revealed increased capillary density basally in the KO hearts, which was further elevated relative to wild-type mouse hearts in response to pressure overload. In vitro studies with isolated myocytes in co-culture also demonstrated that PHLPP1 deletion in cardiomyocytes can enhance endothelial tube formation. Expression of the pro-angiogenic factor VEGF was also elevated basally and accentuated in response to transverse aortic constriction in hearts from KO mice. Our data suggest that enhancing Akt activity by inhibiting its PHLPP1-mediated dephosphorylation promotes processes associated with physiological hypertrophy that may be beneficial in attenuating the development of pathological hypertrophy. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

Multidisciplinary emergent removal of a metal penoscrotal constriction device.

PubMed

Nason, G J; Abdelsadek, A H; Foran, A T; O'Malley, K J

2017-03-10

Strangulation of the genital organs is a rare presentation to the emergency department which requires urgent intervention to avoid long term complications. Penoscrotal constriction devices are either used for autoerotic stimulus or to increase sexual performance by maintaining an erection for a longer period. We report a case of a man who presented with penile strangulation following the application of a titanium penoscrotal constriction ring during sexual intercourse seven hours previously. The Fire Brigade department attended with an electric operated angle grinder to facilitate removal of the ring as standard medical equipment (orthopaedic saws, bolt and bone cutters) were insufficient. Fully functional recovery was achieved.

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.

Symmetry breaking in clogging for oppositely driven particles

NASA Astrophysics Data System (ADS)

Glanz, Tobias; Wittkowski, Raphael; Löwen, Hartmut

2016-11-01

The clogging behavior of a symmetric binary mixture of colloidal particles that are driven in opposite directions through constrictions is explored by Brownian dynamics simulations and theory. A dynamical state with a spontaneously broken symmetry occurs where one species is flowing and the other is blocked for a long time, which can be tailored by the size of the constrictions. Moreover, we find self-organized oscillations in clogging and unclogging of the two species. Apart from statistical physics, our results are of relevance for fields like biology, chemistry, and crowd management, where ions, microparticles, pedestrians, or other particles are driven in opposite directions through constrictions.

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 < 0.00001) in CO + FS vs 82 ± 61% in ME + FS (P < 0.007). CONCLUSIONS In a senescent non-human primate model for coronary artery bypass grafts, constrictive, external mesh support of saphenous veins with knitted nitinol prevented focal, irregular graft narrowing and suppressed neointimal tissue proliferation by a factor of 2.5. The lower degree of suppression of IH compared with previous infrainguinal grafts coincided with a lesser reduction of calibre mismatch in the coronary grafts. PMID:23295444

Emotional expression and heart rate in high-risk infants during the face-to-face/still-face.

PubMed

Mattson, Whitney I; Ekas, Naomi V; Lambert, Brittany; Tronick, Ed; Lester, Barry M; Messinger, Daniel S

2013-12-01

In infants, eye constriction-the Duchenne marker-and mouth opening appear to index the intensity of both positive and negative facial expressions. We combined eye constriction and mouth opening that co-occurred with smiles and cry-faces (respectively, the prototypic expressions of infant joy and distress) to measure emotional expression intensity. Expression intensity and heart rate were measured throughout the face-to-face/still-face (FFSF) in a sample of infants with prenatal cocaine exposure who were at risk for developmental difficulties. Smiles declined and cry-faces increased in the still-face episode, but the distribution of eye constriction and mouth opening in smiles and cry-faces did not differ across episodes of the FFSF. As time elapsed in the still face episode potential indices of intensity increased, cry-faces were more likely to be accompanied by eye constriction and mouth opening. During cry-faces there were also moderately stable individual differences in the quantity of eye constriction and mouth opening. Infant heart rate was higher during cry-faces and lower during smiles, but did not vary with intensity of expression or by episode. In sum, infants express more intense negative affect as the still-face progresses, but do not show clear differences in expressive intensity between episodes of the FFSF. Copyright © 2013 Elsevier Inc. All rights reserved.

Abnormal Transient Pupillary Light Reflex in Individuals with Autism Spectrum Disorders

ERIC Educational Resources Information Center

Fan, Xiaofei; Miles, Judith H.; Takahashi, Nicole; Yao, Gang

2009-01-01

Computerized binocular infrared pupillography was used to measure the transient pupillary light reflex (PLR) in both children with autism spectrum disorders (ASDs) and children with typical development. We found that participants with ASDs showed significantly longer PLR latency, smaller constriction amplitude and lower constriction velocity than…

Ryanodine receptor phosphorylation by calcium/calmodulin-dependent protein kinase II promotes life-threatening ventricular arrhythmias in mice with heart failure.

PubMed

van Oort, Ralph J; McCauley, Mark D; Dixit, Sayali S; Pereira, Laetitia; Yang, Yi; Respress, Jonathan L; Wang, Qiongling; De Almeida, Angela C; Skapura, Darlene G; Anderson, Mark E; Bers, Donald M; Wehrens, Xander H T

2010-12-21

approximately half of patients with heart failure die suddenly as a result of ventricular arrhythmias. Although abnormal Ca(2+) release from the sarcoplasmic reticulum through ryanodine receptors (RyR2) has been linked to arrhythmogenesis, the molecular mechanisms triggering release of arrhythmogenic Ca(2+) remain unknown. We tested the hypothesis that increased RyR2 phosphorylation by Ca(2+)/calmodulin-dependent protein kinase II is both necessary and sufficient to promote lethal ventricular arrhythmias. mice in which the S2814 Ca(2+)/calmodulin-dependent protein kinase II site on RyR2 is constitutively activated (S2814D) develop pathological sarcoplasmic reticulum Ca(2+) release events, resulting in reduced sarcoplasmic reticulum Ca(2+) load on confocal microscopy. These Ca(2+) release events are associated with increased RyR2 open probability in lipid bilayer preparations. At baseline, young S2814D mice have structurally and functionally normal hearts without arrhythmias; however, they develop sustained ventricular tachycardia and sudden cardiac death on catecholaminergic provocation by caffeine/epinephrine or programmed electric stimulation. Young S2814D mice have a significant predisposition to sudden arrhythmogenic death after transverse aortic constriction surgery. Finally, genetic ablation of the Ca(2+)/calmodulin-dependent protein kinase II site on RyR2 (S2814A) protects mutant mice from pacing-induced arrhythmias versus wild-type mice after transverse aortic constriction surgery. our results suggest that Ca(2+)/calmodulin-dependent protein kinase II phosphorylation of RyR2 Ca(2+) release channels at S2814 plays an important role in arrhythmogenesis and sudden cardiac death in mice with heart failure.

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

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.

Death Anxiety and Disengagement.

ERIC Educational Resources Information Center

Fried-Cassorla, Martha

This study hypothisized that when a person perceives his social network as constricted, and this constriction has been a "conscious" decision by that individual, then he or she should express little death anxiety. Subjects were 38 individuals who were at least age 60. Of these, 18 were members of the Gray Panthers (with expanding numbers of social…

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.

A case report of umbilical ring constriction with application of amnioinfusion.

PubMed

Tokunaka, Mayumi; Hasegawa, Junichi; Nakamura, Masamitsu; Hamada, Shoko; Matsuoka, Ryu; Ichizuka, Kiyotake; Sekizawa, Akihiko; Okai, Takashi

2013-07-01

This is a case report of a pregnant 38-year-old primigravida woman. Due to severe fetal growth restriction and oligohydramnios, she was referred to our tertiary perinatal center at 24 weeks' gestation. To rule out chromosomal abnormalities and facilitate ultrasound evaluation of fetal morphology, we performed amniocentesis and subsequent amnioinfusion. Thereafter, a precise ultrasound examination revealed no obvious fetal morphological abnormalities except for a hyper-coiled cord and marginal placenta previa. During expectant management, the amount of amniotic fluid was maintained at 20-26 mm for a few days; however, the pregnancy resulted in intrauterine fetal death after 26 weeks + 5 days of gestation. The stillborn infant weighed 530 g (-3.3 SD) and had no obvious external abnormalities apart from umbilical ring constriction. Although a postmortem autopsy was not performed, it is suspected that the fetal growth restriction and the intrauterine fetal death were associated with the hyper-coiled cord and the umbilical ring constriction. It is thought that umbilical ring constriction might therefore be an irreversible fatal condition in cases with a hyper-coiled cord.

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.

A mitochondria-anchored isoform of the actin-nucleating spire protein regulates mitochondrial division.

PubMed

Manor, Uri; Bartholomew, Sadie; Golani, Gonen; Christenson, Eric; Kozlov, Michael; Higgs, Henry; Spudich, James; Lippincott-Schwartz, Jennifer

2015-08-25

Mitochondrial division, essential for survival in mammals, is enhanced by an inter-organellar process involving ER tubules encircling and constricting mitochondria. The force for constriction is thought to involve actin polymerization by the ER-anchored isoform of the formin protein inverted formin 2 (INF2). Unknown is the mechanism triggering INF2-mediated actin polymerization at ER-mitochondria intersections. We show that a novel isoform of the formin-binding, actin-nucleating protein Spire, Spire1C, localizes to mitochondria and directly links mitochondria to the actin cytoskeleton and the ER. Spire1C binds INF2 and promotes actin assembly on mitochondrial surfaces. Disrupting either Spire1C actin- or formin-binding activities reduces mitochondrial constriction and division. We propose Spire1C cooperates with INF2 to regulate actin assembly at ER-mitochondrial contacts. Simulations support this model's feasibility and demonstrate polymerizing actin filaments can induce mitochondrial constriction. Thus, Spire1C is optimally positioned to serve as a molecular hub that links mitochondria to actin and the ER for regulation of mitochondrial division.

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.

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

Pupil-mimicry conditions trust in partners: moderation by oxytocin and group membership

PubMed Central

De Dreu, Carsten K. W.

2017-01-01

Across species, oxytocin, an evolutionarily ancient neuropeptide, facilitates social communication by attuning individuals to conspecifics' social signals, fostering trust and bonding. The eyes have an important signalling function; and humans use their salient and communicative eyes to intentionally and unintentionally send social signals to others, by contracting the muscles around their eyes and pupils. In our earlier research, we observed that interaction partners with dilating pupils are trusted more than partners with constricting pupils. But over and beyond this effect, we found that the pupil sizes of partners synchronize and that when pupils synchronously dilate, trust is further boosted. Critically, this linkage between mimicry and trust was bound to interactions between ingroup members. The current study investigates whether these findings are modulated by oxytocin and sex of participant and partner. Using incentivized trust games with partners from ingroup and outgroup whose pupils dilated, remained static or constricted, this study replicates our earlier findings. It further reveals that (i) male participants withhold trust from partners with constricting pupils and extend trust to partners with dilating pupils, especially when given oxytocin rather than placebo; (ii) female participants trust partners with dilating pupils most, but this effect is blunted under oxytocin; (iii) under oxytocin rather than placebo, pupil dilation mimicry is weaker and pupil constriction mimicry stronger; and (iv) the link between pupil constriction mimicry and distrust observed under placebo disappears under oxytocin. We suggest that pupil-contingent trust is parochial and evolved in social species in and because of group life. PMID:28250181

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

Redox Signaling via Oxidative Inactivation of PTEN Modulates Pressure-Dependent Myogenic Tone in Rat Middle Cerebral Arteries

PubMed Central

Gebremedhin, Debebe; Terashvili, Maia; Wickramasekera, Nadi; Zhang, David X.; Rau, Nicole; Miura, Hiroto; Harder, David R.

2013-01-01

The present study examined the level of generation of reactive oxygen species (ROS) and roles of inactivation of the phosphatase PTEN and the PI3K/Akt signaling pathway in response to an increase in intramural pressure-induced myogenic cerebral arterial constriction. Step increases in intraluminal pressure of cannulated cerebral arteries induced myogenic constriction and concomitant formation of superoxide (O2 .−) and its dismutation product hydrogen peroxide (H2O2) as determined by fluorescent HPLC analysis, microscopic analysis of intensity of dihydroethidium fluorescence and attenuation of pressure-induced myogenic constriction by pretreatment with the ROS scavenger 4,hydroxyl-2,2,6,6-tetramethylpiperidine1-oxyl (tempol) or Mito-tempol or MitoQ in the presence or absence of PEG-catalase. An increase in intraluminal pressure induced oxidation of PTEN and activation of Akt. Pharmacological inhibition of endogenous PTEN activity potentiated pressure-dependent myogenic constriction and caused a reduction in NPo of a 238 pS arterial KCa channel current and an increase in [Ca2+]i level in freshly isolated cerebral arterial muscle cells (CAMCs), responses that were attenuated by Inhibition of the PI3K/Akt pathway. These findings demonstrate an increase in intraluminal pressure induced increase in ROS production triggered redox-sensitive signaling mechanism emanating from the cross-talk between oxidative inactivation of PTEN and activation of the PI3K/Akt signaling pathway that involves in the regulation of pressure-dependent myogenic cerebral arterial constriction. PMID:23861911

Redox signaling via oxidative inactivation of PTEN modulates pressure-dependent myogenic tone in rat middle cerebral arteries.

PubMed

Gebremedhin, Debebe; Terashvili, Maia; Wickramasekera, Nadi; Zhang, David X; Rau, Nicole; Miura, Hiroto; Harder, David R

2013-01-01

The present study examined the level of generation of reactive oxygen species (ROS) and roles of inactivation of the phosphatase PTEN and the PI3K/Akt signaling pathway in response to an increase in intramural pressure-induced myogenic cerebral arterial constriction. Step increases in intraluminal pressure of cannulated cerebral arteries induced myogenic constriction and concomitant formation of superoxide (O2 (.-)) and its dismutation product hydrogen peroxide (H2O2) as determined by fluorescent HPLC analysis, microscopic analysis of intensity of dihydroethidium fluorescence and attenuation of pressure-induced myogenic constriction by pretreatment with the ROS scavenger 4,hydroxyl-2,2,6,6-tetramethylpiperidine1-oxyl (tempol) or Mito-tempol or MitoQ in the presence or absence of PEG-catalase. An increase in intraluminal pressure induced oxidation of PTEN and activation of Akt. Pharmacological inhibition of endogenous PTEN activity potentiated pressure-dependent myogenic constriction and caused a reduction in NPo of a 238 pS arterial KCa channel current and an increase in [Ca(2+)]i level in freshly isolated cerebral arterial muscle cells (CAMCs), responses that were attenuated by Inhibition of the PI3K/Akt pathway. These findings demonstrate an increase in intraluminal pressure induced increase in ROS production triggered redox-sensitive signaling mechanism emanating from the cross-talk between oxidative inactivation of PTEN and activation of the PI3K/Akt signaling pathway that involves in the regulation of pressure-dependent myogenic cerebral arterial constriction.

Distinct right ventricle remodeling in response to pressure overload in the rat.

PubMed

Mendes-Ferreira, P; Santos-Ribeiro, D; Adão, R; Maia-Rocha, C; Mendes-Ferreira, M; Sousa-Mendes, C; Leite-Moreira, A F; Brás-Silva, C

2016-07-01

Pulmonary arterial hypertension (PAH), the most serious chronic disorder of the pulmonary circulation, is characterized by pulmonary vasoconstriction and remodeling, resulting in increased afterload on the right ventricle (RV). In fact, RV function is the main determinant of prognosis in PAH. The most frequently used experimental models of PAH include monocrotaline- and chronic hypoxia-induced PAH, which primarily affect the pulmonary circulation. Alternatively, pulmonary artery banding (PAB) can be performed to achieve RV overload without affecting the pulmonary vasculature, allowing researchers to determine the RV-specific effects of their drugs/interventions. In this work, using two different degrees of pulmonary artery constriction, we characterize, in full detail, PAB-induced adaptive and maladaptive remodeling of the RV at 3 wk after PAB surgery. Our results show that application of a mild constriction resulted in adaptive hypertrophy of the RV, with preserved systolic and diastolic function, while application of a severe constriction resulted in maladaptive hypertrophy, with chamber dilation and systolic and diastolic dysfunction up to the isolated cardiomyocyte level. By applying two different degrees of constriction, we describe, for the first time, a reliable and short-duration PAB model in which RV adaptation can be distinguished at 3 wk after surgery. We characterize, in full detail, structural and functional changes of the RV in its response to moderate and severe constriction, allowing researchers to better study RV physiology and transition to dysfunction and failure, as well as to determine the effects of new therapies. Copyright © 2016 the American Physiological Society.

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

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 in practice.

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

Shear-stress sensitive lenticular vesicles for targeted drug delivery.

PubMed

Holme, Margaret N; Fedotenko, Illya A; Abegg, Daniel; Althaus, Jasmin; Babel, Lucille; Favarger, France; Reiter, Renate; Tanasescu, Radu; Zaffalon, Pierre-Léonard; Ziegler, André; Müller, Bert; Saxer, Till; Zumbuehl, Andreas

2012-08-01

Atherosclerosis results in the narrowing of arterial blood vessels and this causes significant changes in the endogenous shear stress between healthy and constricted arteries. Nanocontainers that can release drugs locally with such rheological changes can be very useful. Here, we show that vesicles made from an artificial 1,3-diaminophospholipid are stable under static conditions but release their contents at elevated shear stress. These vesicles have a lenticular morphology, which potentially leads to instabilities along their equator. Using a model cardiovascular system based on polymer tubes and an external pump to represent shear stress in healthy and constricted vessels of the heart, we show that drugs preferentially release from the vesicles in constricted vessels that have high shear stress.

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.

Role of distal reabsorption and peritubular environment in glomerulotubular balance.

NASA Technical Reports Server (NTRS)

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

1972-01-01

Total kidney glomerulotubular balance was examined during aortic constriction and release in saline-loaded dogs and in dogs undergoing water diuresis. Aortic constriction lowered the glomerular filtration rate by 45% in both groups, and glomerulotubular balance, as judged by changes in absolute sodium reabsorption, was also comparable. During water diuresis, a linear relationship was observed between free water clearance and urine flow during all maneuvers, suggesting that distal sodium reabsorption is related primarily to distal delivery. The results suggest that if alterations in the peritubular environment are responsible for the changes in tubular sodium reabsorption during aortic constriction in the saline- or water-loaded dog, then a change in renal plasma flow, and presumably delivery rate of oncotic force, may be the most likely mediator.

Shear-stress sensitive lenticular vesicles for targeted drug delivery

NASA Astrophysics Data System (ADS)

Holme, Margaret N.; Fedotenko, Illya A.; Abegg, Daniel; Althaus, Jasmin; Babel, Lucille; Favarger, France; Reiter, Renate; Tanasescu, Radu; Zaffalon, Pierre-Léonard; Ziegler, André; Müller, Bert; Saxer, Till; Zumbuehl, Andreas

2012-08-01

Atherosclerosis results in the narrowing of arterial blood vessels and this causes significant changes in the endogenous shear stress between healthy and constricted arteries. Nanocontainers that can release drugs locally with such rheological changes can be very useful. Here, we show that vesicles made from an artificial 1,3-diaminophospholipid are stable under static conditions but release their contents at elevated shear stress. These vesicles have a lenticular morphology, which potentially leads to instabilities along their equator. Using a model cardiovascular system based on polymer tubes and an external pump to represent shear stress in healthy and constricted vessels of the heart, we show that drugs preferentially release from the vesicles in constricted vessels that have high shear stress.

PDE1C deficiency antagonizes pathological cardiac remodeling and dysfunction

PubMed Central

Knight, Walter E.; Chen, Si; Zhang, Yishuai; Oikawa, Masayoshi; Wu, Meiping; Zhou, Qian; Miller, Clint L.; Cai, Yujun; Mickelsen, Deanne M.; Moravec, Christine; Small, Eric M.; Abe, Junichi; Yan, Chen

2016-01-01

Cyclic nucleotide phosphodiesterase 1C (PDE1C) represents a major phosphodiesterase activity in human myocardium, but its function in the heart remains unknown. Using genetic and pharmacological approaches, we studied the expression, regulation, function, and underlying mechanisms of PDE1C in the pathogenesis of cardiac remodeling and dysfunction. PDE1C expression is up-regulated in mouse and human failing hearts and is highly expressed in cardiac myocytes but not in fibroblasts. In adult mouse cardiac myocytes, PDE1C deficiency or inhibition attenuated myocyte death and apoptosis, which was largely dependent on cyclic AMP/PKA and PI3K/AKT signaling. PDE1C deficiency also attenuated cardiac myocyte hypertrophy in a PKA-dependent manner. Conditioned medium taken from PDE1C-deficient cardiac myocytes attenuated TGF-β–stimulated cardiac fibroblast activation through a mechanism involving the crosstalk between cardiac myocytes and fibroblasts. In vivo, cardiac remodeling and dysfunction induced by transverse aortic constriction, including myocardial hypertrophy, apoptosis, cardiac fibrosis, and loss of contractile function, were significantly attenuated in PDE1C-knockout mice relative to wild-type mice. These results indicate that PDE1C activation plays a causative role in pathological cardiac remodeling and dysfunction. Given the continued development of highly specific PDE1 inhibitors and the high expression level of PDE1C in the human heart, our findings could have considerable therapeutic significance. PMID:27791092

Deficiency of aldose reductase exacerbates early pressure overload-induced cardiac dysfunction and autophagy in mice.

PubMed

Baba, Shahid P; Zhang, Deqing; Singh, Mahavir; Dassanayaka, Sujith; Xie, Zhengzhi; Jagatheesan, Ganapathy; Zhao, Jingjing; Schmidtke, Virginia K; Brittian, Kenneth R; Merchant, Michael L; Conklin, Daniel J; Jones, Steven P; Bhatnagar, Aruni

2018-05-01

Pathological cardiac hypertrophy is associated with the accumulation of lipid peroxidation-derived aldehydes such as 4-hydroxy-trans-2-nonenal (HNE) and acrolein in the heart. These aldehydes are metabolized via several pathways, of which aldose reductase (AR) represents a broad-specificity route for their elimination. We tested the hypothesis that by preventing aldehyde removal, AR deficiency accentuates the pathological effects of transverse aortic constriction (TAC). We found that the levels of AR in the heart were increased in mice subjected to TAC for 2 weeks. In comparison with wild-type (WT), AR-null mice showed lower ejection fraction, which was exacerbated 2 weeks after TAC. Levels of atrial natriuretic peptide and myosin heavy chain were higher in AR-null than in WT TAC hearts. Deficiency of AR decreased urinary levels of the acrolein metabolite, 3-hydroxypropylmercapturic acid. Deletion of AR did not affect the levels of the other aldehyde-metabolizing enzyme - aldehyde dehydrogenase 2 in the heart, or its urinary product - (N-Acetyl-S-(2-carboxyethyl)-l-cystiene). AR-null hearts subjected to TAC showed increased accumulation of HNE- and acrolein-modified proteins, as well as increased AMPK phosphorylation and autophagy. Superfusion with HNE led to a greater increase in p62, LC3II formation, and GFP-LC3-II punctae formation in AR-null than WT cardiac myocytes. Pharmacological inactivation of JNK decreased HNE-induced autophagy in AR-null cardiac myocytes. Collectively, these results suggest that during hypertrophy the accumulation of lipid peroxidation derived aldehydes promotes pathological remodeling via excessive autophagy, and that metabolic detoxification of these aldehydes by AR may be essential for maintaining cardiac function during early stages of pressure overload. Published by Elsevier Ltd.

Sildenafil ameliorates right ventricular early molecular derangement during left ventricular pressure overload.

PubMed

Imai, Yousuke; Kariya, Taro; Iwakiri, Masaki; Yamada, Yoshitsugu; Takimoto, Eiki

2018-01-01

Right ventricular (RV) dysfunction following left ventricular (LV) failure is associated with poor prognosis. RV remodeling is thought initiated by the increase in the afterload of RV due to secondary pulmonary hypertension (PH) to impaired LV function; however, RV molecular changes might occur in earlier stages of the disease. cGMP (cyclic guanosine monophosphate)-phosphodiesterase 5 (PDE5) inhibitors, widely used to treat PH through their pulmonary vasorelaxation properties, have shown direct cardiac benefits, but their impacts on the RV in LV diseases are not fully determined. Here we show that RV molecular alterations occur early in the absence of RV hemodynamic changes during LV pressure-overload and are ameliorated by PDE5 inhibition. Two-day moderate LV pressure-overload (transverse aortic constriction) neither altered RV pressure/ function nor RV weight in mice, while it induced only mild LV hypertrophy. Importantly, pathological molecular features were already induced in the RV free wall myocardium, including up-regulation of gene markers for hypertrophy and inflammation, and activation of extracellular signal-regulated kinase (ERK) and calcineurin. Concomitant PDE5 inhibition (sildenafil) prevented induction of such pathological genes and activation of ERK and calcineurin in the RV as well as in the LV. Importantly, dexamethasone also prevented these RV molecular changes, similarly to sildenafil treatment. These results suggest the contributory role of inflammation to the early pathological interventricular interaction between RV and LV. The current study provides the first evidence for the novel early molecular cross-talk between RV and LV, preceding RV hemodynamic changes in LV disease, and supports the therapeutic strategy of enhancing cGMP signaling pathway to treat heart diseases.

Novel experimental model of pressure overload hypertrophy in rats.

PubMed

Molina, Ezequiel J; Gupta, Dipin; Palma, Jon; Torres, Denise; Gaughan, John P; Houser, Steven; Macha, Mahender

2009-05-15

We studied a novel animal model of pressure overload hypertrophy in transition to heart failure following ascending aortic constriction. We sought to assess chronologic changes in hemodynamic parameters, echocardiographic signs of left ventricular (LV) remodeling, exercise tolerance, and profiles of systemic and local inflammation. A cohort of Sprague Dawley rats underwent aortic constriction proximal to the innominate artery and were followed by echocardiography. A group of animals were euthanized 20 wk after aortic constriction, before any detectable decline in fractional shortening (normal fractional shortening (FS) or control group; n = 6). When additional animals reached an absolute 25% decline in fractional shortening, they were randomized to be euthanized on d 0 (25% downward arrow FS group; n = 5), or d 21 (>25% downward arrow FS group; n = 6). Hemodynamic and echocardiographic assessment, swim testing to exhaustion, and measurement of systemic and local inflammatory markers was performed at each time interval. An absolute decline of 25% in FS after aortic constriction was observed between 24 and 28 wk for most animals. The transition from compensated to decompensated hypertrophy was associated with markedly decreased dP/dt(max) and dP/dt(min), increased LV end-systolic diameter and LV end-diastolic diameter, stabilization of LV free wall diameter, decreased exercise performance and up-regulation in expression of interleukin-1, interleukin-6, tumor necrosis factor-alpha, and atrial natriuretic peptide. All animals developed heart failure. This study demonstrates that proximal aortic constriction in young rats represents an excellent experimental model of pressure overload hypertrophy that may be useful for testing the efficacy of novel therapies for the treatment of heart failure.

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.

The king of snakes: performance and morphology of intraguild predators (Lampropeltis) and their prey (Pantherophis).

PubMed

Penning, David A; Moon, Brad R

2017-03-15

Across ecosystems and trophic levels, predators are usually larger than their prey, and when trophic morphology converges, predators typically avoid predation on intraguild competitors unless the prey is notably smaller in size. However, a currently unexplained exception occurs in kingsnakes in the genus Lampropeltis Kingsnakes are able to capture, constrict and consume other snakes that are not only larger than themselves but that are also powerful constrictors (such as ratsnakes in the genus Pantherophis ). Their mechanisms of success as intraguild predators on other constrictors remain unknown. To begin addressing these mechanisms, we studied the scaling of muscle cross-sectional area, pulling force and constriction pressure across the ontogeny of six species of snakes ( Lampropeltis californiae , L. getula , L. holbrooki , Pantherophis alleghaniensis , P. guttatus and P. obsoletus ). Muscle cross-sectional area is an indicator of potential force production, pulling force is an indicator of escape performance, and constriction pressure is a measure of prey-handling performance. Muscle cross-sectional area scaled similarly for all snakes, and there was no significant difference in maximum pulling force among species. However, kingsnakes exerted significantly higher pressures on their prey than ratsnakes. The similar escape performance among species indicates that kingsnakes win in predatory encounters because of their superior constriction performance, not because ratsnakes have inferior escape performance. The superior constriction performance by kingsnakes results from their consistent and distinctive coil posture and perhaps from additional aspects of muscle structure and function that need to be tested in future research. © 2017. Published by The Company of Biologists Ltd.

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.

Pupil-mimicry conditions trust in partners: moderation by oxytocin and group membership.

PubMed

Kret, Mariska E; De Dreu, Carsten K W

2017-03-15

Across species, oxytocin, an evolutionarily ancient neuropeptide, facilitates social communication by attuning individuals to conspecifics' social signals, fostering trust and bonding. The eyes have an important signalling function; and humans use their salient and communicative eyes to intentionally and unintentionally send social signals to others, by contracting the muscles around their eyes and pupils. In our earlier research, we observed that interaction partners with dilating pupils are trusted more than partners with constricting pupils. But over and beyond this effect, we found that the pupil sizes of partners synchronize and that when pupils synchronously dilate, trust is further boosted. Critically, this linkage between mimicry and trust was bound to interactions between ingroup members. The current study investigates whether these findings are modulated by oxytocin and sex of participant and partner. Using incentivized trust games with partners from ingroup and outgroup whose pupils dilated, remained static or constricted, this study replicates our earlier findings. It further reveals that (i) male participants withhold trust from partners with constricting pupils and extend trust to partners with dilating pupils, especially when given oxytocin rather than placebo; (ii) female participants trust partners with dilating pupils most, but this effect is blunted under oxytocin; (iii) under oxytocin rather than placebo, pupil dilation mimicry is weaker and pupil constriction mimicry stronger; and (iv) the link between pupil constriction mimicry and distrust observed under placebo disappears under oxytocin. We suggest that pupil-contingent trust is parochial and evolved in social species in and because of group life. © 2017 The Authors.

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

The effect of deep brain stimulation on the speech motor system.

PubMed

Mücke, Doris; Becker, Johannes; Barbe, Michael T; Meister, Ingo; Liebhart, Lena; Roettger, Timo B; Dembek, Till; Timmermann, Lars; Grice, Martine

2014-08-01

Chronic deep brain stimulation of the nucleus ventralis intermedius is an effective treatment for individuals with medication-resistant essential tremor. However, these individuals report that stimulation has a deleterious effect on their speech. The present study investigates one important factor leading to these effects: the coordination of oral and glottal articulation. Sixteen native-speaking German adults with essential tremor, between 26 and 86 years old, with and without chronic deep brain stimulation of the nucleus ventralis intermedius and 12 healthy, age-matched subjects were recorded performing a fast syllable repetition task (/papapa/, /tatata/, /kakaka/). Syllable duration and voicing-to-syllable ratio as well as parameters related directly to consonant production, voicing during constriction, and frication during constriction were measured. Voicing during constriction was greater in subjects with essential tremor than in controls, indicating a perseveration of voicing into the voiceless consonant. Stimulation led to fewer voiceless intervals (voicing-to-syllable ratio), indicating a reduced degree of glottal abduction during the entire syllable cycle. Stimulation also induced incomplete oral closures (frication during constriction), indicating imprecise oral articulation. The detrimental effect of stimulation on the speech motor system can be quantified using acoustic measures at the subsyllabic level.

Adaptation of mesenteric lymphatic vessels to prolonged changes in transmural pressure.

PubMed

Dongaonkar, R M; Nguyen, T L; Quick, C M; Hardy, J; Laine, G A; Wilson, E; Stewart, R H

2013-07-15

In vitro studies have revealed that acute increases in transmural pressure increase lymphatic vessel contractile function. However, adaptive responses to prolonged changes in transmural pressure in vivo have not been reported. Therefore, we developed a novel bovine mesenteric lymphatic partial constriction model to test the hypothesis that lymphatic vessels exposed to higher transmural pressures adapt functionally to become stronger pumps than vessels exposed to lower transmural pressures. Postnodal mesenteric lymphatic vessels were partially constricted for 3 days. On postoperative day 3, constricted vessels were isolated, and divided into upstream (UP) and downstream (DN) segment groups, and instrumented in an isolated bath. Although there were no differences between the passive diameters of the two groups, both diastolic diameter and systolic diameter were significantly larger in the UP group than in the DN group. The pump index of the UP group was also higher than that in the DN group. In conclusion, this is the first work to report how lymphatic vessels adapt to prolonged changes in transmural pressure in vivo. Our results suggest that vessel segments upstream of the constriction adapt to become both better fluid conduits and lymphatic pumps than downstream segments.

A mitochondria-anchored isoform of the actin-nucleating spire protein regulates mitochondrial division

PubMed Central

Manor, Uri; Bartholomew, Sadie; Golani, Gonen; Christenson, Eric; Kozlov, Michael; Higgs, Henry; Spudich, James; Lippincott-Schwartz, Jennifer

2015-01-01

Mitochondrial division, essential for survival in mammals, is enhanced by an inter-organellar process involving ER tubules encircling and constricting mitochondria. The force for constriction is thought to involve actin polymerization by the ER-anchored isoform of the formin protein inverted formin 2 (INF2). Unknown is the mechanism triggering INF2-mediated actin polymerization at ER-mitochondria intersections. We show that a novel isoform of the formin-binding, actin-nucleating protein Spire, Spire1C, localizes to mitochondria and directly links mitochondria to the actin cytoskeleton and the ER. Spire1C binds INF2 and promotes actin assembly on mitochondrial surfaces. Disrupting either Spire1C actin- or formin-binding activities reduces mitochondrial constriction and division. We propose Spire1C cooperates with INF2 to regulate actin assembly at ER-mitochondrial contacts. Simulations support this model's feasibility and demonstrate polymerizing actin filaments can induce mitochondrial constriction. Thus, Spire1C is optimally positioned to serve as a molecular hub that links mitochondria to actin and the ER for regulation of mitochondrial division. DOI: http://dx.doi.org/10.7554/eLife.08828.001 PMID:26305500

Design and analysis of coiled fiber reinforced soft pneumatic actuator.

PubMed

Singh, Gaurav; Xiao, Chenzhang; Hsiao-Wecksler, Elizabeth T; Krishnan, Girish

2018-04-18

Fiber reinforced elastomeric enclosures (FREEs) are soft pneumatic actuators that can contract and generate forces upon pressurization. Typical engineering applications utilize FREEs in their straight cylindrical configuration and derive actuation displacement and forces from their ends. However, there are several instances in nature, such as an elephant trunk, snakes and grapevine tendrils, where a spiral configuration of muscle systems is used for gripping, thereby establishing a mechanical connection with uniform force distribution. Inspired by these examples, this paper investigates the constricting behavior of a contracting FREE actuator deployed in a spiral or coiled configuration around a cylindrical object. Force balance is used to model the blocked force of the FREE, which is then related to the constriction force using a string model. The modeling and experimental findings reveal an attenuation in the blocked force, and thus the constriction force caused by the coupling of peripheral contact forces acting in the spiral configuration. The usefulness of the coiled FREE configuration is demonstrated in a soft arm orthosis for crutch users that provides a constriction force around the forearm. This design minimizes injury risk by reducing wrist load and improving wrist posture.

Hemiplegic shoulder pain: implications for occupational therapy treatment.

PubMed

Gilmore, Paula E; Spaulding, Sandi J; Vandervoort, Anthony A

2004-02-01

Hemiplegic shoulder pain is common after stroke causing hemiplegia. It adversely affects the recovery of arm function and independence in activities of daily living. Subluxation, abnormal tone and limited range of motion or capsular constrictions have been reported as potential causes. Other factors such as rotator cuff tears, brachial plexus injury, shoulder-hand syndrome and other pre-existing pathological conditions may also be associated with hemiplegic shoulder pain. The etiology remains unclear, but hemiplegic shoulder pain may result from a combination of the above factors. This literature review examines the possible causes of hemiplegic shoulder pain and discusses the implications for occupational therapy treatment. Occupational therapy interventions include proper positioning, facilitation of movement through purposeful therapeutic activities, increasing passive range of motion, implementation of external supports and treatment of shoulder-hand syndrome. Understanding the processes involved will assist with effective assessment, treatment and prevention of hemiplegic shoulder pain. This will facilitate clients' participation in rehabilitation programs and move them towards attainment of optimal function.

H2O2 sensors of lungs and blood vessels and their role in the antioxidant defense of the body.

PubMed

Skulachev, V P

2001-10-01

This paper considers the composition and function of sensory systems monitoring H2O2 level by the lung neuroepithelial cells and carotid bodies. These systems are localized in the plasma membrane of the corresponding cells and are composed of (O2*-)-generating NADPH-oxidase and an H2O2-activated K+ channel. This complex structure of the H2O2 sensors is probably due to their function in antioxidant defense. By means of these sensors, an increase in the H2O2 level in lung or blood results in a decrease in lung ventilation and constriction of blood vessels. This action lowers the O2 flux to the tissues and, hence, intracellular [O2]. The [O2] decrease, in turn, inhibits intracellular generation of reactive oxygen species. The possible roles of such systems under normal conditions (e.g., the effect of O2*- in air) and in some pathologies (e.g., pneumonia) is discussed.

An electrostatic mechanism for Ca2+-mediated regulation of gap junction channels

PubMed Central

Bennett, Brad C.; Purdy, Michael D.; Baker, Kent A.; Acharya, Chayan; McIntire, William E.; Stevens, Raymond C.; Zhang, Qinghai; Harris, Andrew L.; Abagyan, Ruben; Yeager, Mark

2016-01-01

Gap junction channels mediate intercellular signalling that is crucial in tissue development, homeostasis and pathologic states such as cardiac arrhythmias, cancer and trauma. To explore the mechanism by which Ca2+ blocks intercellular communication during tissue injury, we determined the X-ray crystal structures of the human Cx26 gap junction channel with and without bound Ca2+. The two structures were nearly identical, ruling out both a large-scale structural change and a local steric constriction of the pore. Ca2+ coordination sites reside at the interfaces between adjacent subunits, near the entrance to the extracellular gap, where local, side chain conformational rearrangements enable Ca2+chelation. Computational analysis revealed that Ca2+-binding generates a positive electrostatic barrier that substantially inhibits permeation of cations such as K+ into the pore. Our results provide structural evidence for a unique mechanism of channel regulation: ionic conduction block via an electrostatic barrier rather than steric occlusion of the channel pore. PMID:26753910

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.

CoMIC, the hidden dynamics of mitochondrial inner compartments

PubMed Central

Cho, Bongki; Sun, Woong

2017-01-01

Mitochondria have evolutionarily, functionally and structurally distinct outer- (OMM) and inner-membranes (IMM). Thus, mitochondrial morphology is controlled by independent but coordinated activity of fission and fusion of the OMM and IMM. Constriction and division of the OMM are mediated by endocytosis-like machineries, which include dynamin-related protein 1 with additional cytosolic vesicle scissoring machineries such as actin filament and Dynamin 2. However, structural alteration of the IMM during mitochondrial division has been poorly understood. Recently, we found that the IMM and the inner compartments undergo transient and reversible constriction prior to the OMM division, which we termed CoMIC, Constriction of Mitochondrial Inner Compartment. In this short review, we further discuss the evolutionary perspective and the regulatory mechanism of CoMIC during mitochondrial division. PMID:28803609

CoMIC, the hidden dynamics of mitochondrial inner compartments.

PubMed

Cho, Bongki; Sun, Woong

2017-12-01

Mitochondria have evolutionarily, functionally and structurally distinct outer- (OMM) and inner-membranes (IMM). Thus, mitochondrial morphology is controlled by independent but coordinated activity of fission and fusion of the OMM and IMM. Constriction and division of the OMM are mediated by endocytosis-like machineries, which include dynamin-related protein 1 with additional cytosolic vesicle scissoring machineries such as actin filament and Dynamin 2. However, structural alteration of the IMM during mitochondrial division has been poorly understood. Recently, we found that the IMM and the inner compartments undergo transient and reversible constriction prior to the OMM division, which we termed CoMIC, Constriction of Mitochondrial Inner Compartment. In this short review, we further discuss the evolutionary perspective and the regulatory mechanism of CoMIC during mitochondrial division. [BMB Reports 2017; 50(12): 597-598].

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.

Electrothermal flow effects in insulating (electrodeless) dielectrophoresis systems.

PubMed

Hawkins, Benjamin G; Kirby, Brian J

2010-11-01

We simulate electrothermally induced flow in polymeric, insulator-based dielectrophoresis (iDEP) systems with DC-offset, AC electric fields at finite thermal Péclet number, and we identify key regimes where electrothermal (ET) effects enhance particle deflection and trapping. We study a single, two-dimensional constriction in channel depth with parametric variations in electric field, channel geometry, fluid conductivity, particle electrophoretic (EP) mobility, and channel electroosmotic (EO) mobility. We report the effects of increasing particle EP mobility, channel EO mobility, and AC and DC field magnitudes on the mean constriction temperature and particle behavior. Specifically, we quantify particle deflection and trapping, referring to the deviation of particles from their pathlines due to dielectrophoresis as they pass a constriction and the stagnation of particles due to negative dielectrophoresis near a constriction, respectively. This work includes the coupling between fluid, heat, and electromagnetic phenomena via temperature-dependent physical parameters. Results indicate that the temperature distribution depends strongly on the fluid conductivity and electric field magnitude, and particle deflection and trapping depend strongly on the channel geometry. Electrothermal (ET) effects perturb the EO flow field, creating vorticity near the channel constriction and enhancing the deflection and trapping effects. ET effects alter particle deflection and trapping responses in insulator-based dielectrophoresis devices, especially at intermediate device aspect ratios (2 ≤ r ≤ 7) in solutions of higher conductivity (σ m ≥ 1 × 10(-3)S/m). The impact of ET effects on particle deflection and trapping are diminished when particle EP mobility or channel EO mobility is high. In almost all cases, ET effects enhance negative dielectrophoretic particle deflection and trapping phenomena. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Experimental investigation on the vascular thermal response to near-infrared laser pulses.

PubMed

Li, Dong; Chen, Bin; Wu, Wenjuan; Ying, Zhaoxia

2017-12-01

Port wine stains (PWS) are congenital vascular malformations that progressively darken and thicken with age. To improve the effect of laser therapy in clinical practice, thermal response of blood vessel to a 1064 nm Nd:YAG laser with controlled energy doses and pulse durations was evaluated using the dorsal skin chamber model. A total of 137 vessels with 30-300 μm diameters were selected from the dorsal skin of the mouse to match those capillaries in port wine stains. Experimental results showed that the thermal response of blood vessels to 1064 nm laser irradiation can be classified as follows: vessel dilation, coagulation, constriction with decreased diameter, complete constriction, hemorrhage, and collagen damage with increasing laser radiant exposure. In most cases, that is, 83 of 137 blood vessels (60.6%), Nd:YAG laser irradiation was characterized by complete constriction (immediate blood vessel disappearance). To reveal the possible damage mechanisms and evaluate blood vessel photocoagulation patterns, theoretical investigation using bioheat transfer equation was conducted in mouse skin with a depth of 1000 μm. Complete constriction as the dominant thermal response as evidenced by uniform blood heating within the vessel lumen was noted in both experimental observation and theoretical investigation. To achieve the ideal clinical effect using the Nd:YAG laser treatment, the radiant exposure should not only be high enough to induce complete constriction of the blood vessels but also controlled carefully to avoid surrounding collagen damage. The short pulse duration of 1-3 ms is better than long pulse durations because hemorrhaging of small capillaries is occasionally observed postirradiation with pulse durations longer than 10 ms.

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

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 significantly disrupting endothelium-independent, alcohol-induced cerebral artery constriction itself. PMID:26555891

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

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.

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.

An Actin-Dependent Step in Mitochondrial Fission Mediated by the ER-Associated Formin INF2

PubMed Central

Korobova, Farida; Ramabhadran, Vinay; Higgs, Henry N.

2013-01-01

Mitochondrial fission is fundamentally important to cellular physiology. The dynamin-related protein Drp1 mediates fission, and interaction between mitochondrion and endoplasmic reticulum (ER) enhances fission. However, the mechanism for Drp1 recruitment to mitochondria is unclear, although previous results implicate actin involvement. Here, we found that actin polymerization through ER-localized inverted formin 2 (INF2) was required for efficient mitochondrial fission in mammalian cells. INF2 functioned upstream of Drp1. Actin filaments appeared to accumulate between mitochondria and INF2-enriched ER membranes at constriction sites. Thus, INF2-induced actin filaments may drive initial mitochondrial constriction, which allows Drp1-driven secondary constriction. Because INF2 mutations can lead to Charcot-Marie-Tooth disease, our results provide a potential cellular mechanism for this disease state. PMID:23349293

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.

Mucus clearance from the pulmonary system by mechanical means: a dual-excitation approach.

PubMed

Ignagni, Mario; O'Dea, Thomas

2013-01-01

A dual-excitation approach to mechanical clearance of mucus from the pulmonary system is described. The approach employs independently controlled vibratory and constrictive pressure stimulations to the thorax. Patient cooperative efforts are integrated into the therapy regimen as a means of enhancing the efficacy of the treatment. An engineering model that demonstrates the capability to generate vibratory and constrictive pressure variations at specified levels is described.

Novel roles for actin in mitochondrial fission

PubMed Central

Hatch, Anna L.; Gurel, Pinar S.; Higgs, Henry N.

2014-01-01

ABSTRACT Mitochondrial dynamics, including fusion, fission and translocation, are crucial to cellular homeostasis, with roles in cellular polarity, stress response and apoptosis. Mitochondrial fission has received particular attention, owing to links with several neurodegenerative diseases. A central player in fission is the cytoplasmic dynamin-related GTPase Drp1, which oligomerizes at the fission site and hydrolyzes GTP to drive membrane ingression. Drp1 recruitment to the outer mitochondrial membrane (OMM) is a key regulatory event, which appears to require a pre-constriction step in which the endoplasmic reticulum (ER) and mitochondrion interact extensively, a process termed ERMD (ER-associated mitochondrial division). It is unclear how ER–mitochondrial contact generates the force required for pre-constriction or why pre-constriction leads to Drp1 recruitment. Recent results, however, show that ERMD might be an actin-based process in mammals that requires the ER-associated formin INF2 upstream of Drp1, and that myosin II and other actin-binding proteins might be involved. In this Commentary, we present a mechanistic model for mitochondrial fission in which actin and myosin contribute in two ways; firstly, by supplying the force for pre-constriction and secondly, by serving as a coincidence detector for Drp1 binding. In addition, we discuss the possibility that multiple fission mechanisms exist in mammals. PMID:25217628

Changes of the eye optics after iris constriction☆

PubMed Central

Montés-Micó, Robert; Hernández, Patricio; Fernández-Sánchez, Vicente; Bonaque, Sergio; Lara, Francisco; López-Gil, Norberto

2011-01-01

Purpose To evaluate the possible change in the optics of the human eye after iris constriction. Methods Ocular aberrations were measured under natural viewing conditions in 26 eyes. The measured eyes fixated on a dim target while the contralateral eye was either occluded (so the measured eye had a large pupil) or highly illuminated (so the measured eye had a small pupil). The measured eyes fixated to a dim target placed 0.5 D beyond the subject’s far point. Zernike values obtained in both situations were compared within the same pupil diameter corresponding to the one obtained under the high illumination condition. Results Significant variation in some aberration coefficients were found between the two illumination conditions. Specially, spherical aberration (SA) increased significantly after pupil miosis (P = .0017). The mean increase of SA measured was 0.018 microns, for a 3-mm pupil. Mean values of other ocular aberrations also vary significantly after pupil miosis (changes were larger than the standard deviation of the repeated measurements). A mean paraxial hyperopic shift of one third of diopter was found after iris constriction. Conclusion Iris constriction slightly modifies the optics of the eye. The small hyperopic shift of the best image plane after iris constriction may be explained by a change in the lens shape and/or position.

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

Emotional Expression and Heart Rate in High-Risk Infants during the Face-To-Face/Still-Face

PubMed Central

Mattson, Whitney I.; Ekas, Naomi V.; Lambert, Brittany; Tronick, Ed; Lester, Barry M.; Messinger, Daniel S.

2013-01-01

In infants, eye constriction—the Duchenne marker—and mouth opening appear to index the intensity of both positive and negative facial expressions. We combined eye constriction and mouth opening that co-occurred with smiles and cry-faces (respectively, the prototypic expressions of infant joy and distress) to measure emotional expression intensity. Expression intensity and heart rate were measured throughout the Face-to-Face/Still Face (FFSF) in a sample of infants with prenatal cocaine exposure who were at risk for developmental difficulties. Smiles declined and cry-faces increased in the still-face episode, but the distribution of eye constriction and mouth opening in smiles and cry-faces did not differ across episodes of the FFSF. As time elapsed in the still face episode potential indices of intensity increased, cry-faces were more likely to be accompanied by eye constriction and mouth opening. During cry-faces there were also moderately stable individual differences in the quantity of eye constriction and mouth opening. Infant heart rate was higher during cry-faces and lower during smiles, but did not vary with intensity of expression or by episode. In sum, infants express more intense negative affect as the still-face progresses, but do not show clear differences in expressive intensity between episodes of the FFSF. PMID:24095807

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.

Cluster-guided imaging-based CFD analysis of airflow and particle deposition in asthmatic human lungs

NASA Astrophysics Data System (ADS)

Choi, Jiwoong; Leblanc, Lawrence; Choi, Sanghun; Haghighi, Babak; Hoffman, Eric; Lin, Ching-Long

2017-11-01

The goal of this study is to assess inter-subject variability in delivery of orally inhaled drug products to small airways in asthmatic lungs. A recent multiscale imaging-based cluster analysis (MICA) of computed tomography (CT) lung images in an asthmatic cohort identified four clusters with statistically distinct structural and functional phenotypes associating with unique clinical biomarkers. Thus, we aimed to address inter-subject variability via inter-cluster variability. We selected a representative subject from each of the 4 asthma clusters as well as 1 male and 1 female healthy controls, and performed computational fluid and particle simulations on CT-based airway models of these subjects. The results from one severe and one non-severe asthmatic cluster subjects characterized by segmental airway constriction had increased particle deposition efficiency, as compared with the other two cluster subjects (one non-severe and one severe asthmatics) without airway constriction. Constriction-induced jets impinging on distal bifurcations led to excessive particle deposition. The results emphasize the impact of airway constriction on regional particle deposition rather than disease severity, demonstrating the potential of using cluster membership to tailor drug delivery. NIH Grants U01HL114494 and S10-RR022421, and FDA Grant U01FD005837. XSEDE.

Effects of a Proteasome Inhibitor on Cardiomyocytes in a Pressure-Overload Hypertrophy Rat Model: An Animal Study.

PubMed

Kim, In-Sub; Jo, Won-Min

2017-06-01

The ubiquitin-proteasome system (UPS) is an important pathway of proteolysis in pathologic hypertrophic cardiomyocytes. We hypothesize that MG132, a proteasome inhibitor, might prevent hypertrophic cardiomyopathy (CMP) by blocking the UPS. Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and androgen receptor (AR) have been reported to be mediators of CMP and heart failure. This study drew upon pathophysiologic studies and the analysis of NF-κB and AR to assess the cardioprotective effects of MG132 in a left ventricular hypertrophy (LVH) rat model. We constructed a transverse aortic constriction (TAC)-induced LVH rat model with 3 groups: sham (TAC-sham, n=10), control (TAC-cont, n=10), and MG132 administration (TAC-MG132, n=10). MG-132 (0.1 mg/kg) was injected for 4 weeks in the TAC-MG132 group. Pathophysiologic evaluations were performed and the expression of AR and NF-κB was measured in the left ventricle. Fibrosis was prevalent in the pathologic examination of the TAC-cont model, and it was reduced in the TAC-MG132 group, although not significantly. Less expression of AR, but not NF-κB, was found in the TAC-MG132 group than in the TAC-cont group (p<0.05). MG-132 was found to suppress AR in the TAC-CMP model by blocking the UPS, which reduced fibrosis. However, NF-κB expression levels were not related to UPS function.

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.

Quantifying parenchymal tethering in a finite element simulation of a human lung slice under bronchoconstriction.

PubMed

Breen, Barbara J; Donovan, Graham M; Sneyd, James; Tawhai, Merryn H

2012-08-15

Airway hyper-responsiveness (AHR), a hallmark of asthma, is a highly complex phenomenon characterised by multiple processes manifesting over a large range of length and time scales. Multiscale computational models have been derived to embody the experimental understanding of AHR. While current models differ in their derivation, a common assumption is that the increase in parenchymal tethering pressure P(teth) during airway constriction can be described using the model proposed by Lai-Fook (1979), which is based on intact lung experimental data for elastic moduli over a range of inflation pressures. Here we reexamine this relationship for consistency with a nonlinear elastic material law that has been parameterised to the pressure-volume behaviour of the intact lung. We show that the nonlinear law and Lai-Fook's relationship are consistent for small constrictions, but diverge when the constriction becomes large. Copyright © 2012 Elsevier B.V. All rights reserved.

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.

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.

Effects of microRNA-223 on morphine analgesic tolerance by targeting NLRP3 in a rat model of neuropathic pain

PubMed Central

Xie, Xiao-Juan; Ma, Li-Gang; Xi, Kai; Fan, Dong-Mei; Li, Jian-Guo; Zhang, Quan; Zhang, Wei

2017-01-01

Objective To investigate the effects of microRNA-223 on morphine analgesic tolerance by targeting NLRP3 in a rat model of neuropathic pain. Methods Our study selected 100 clean grade healthy Sprague-Dawley adult male rats weighing 200 to 250 g. After establishment of a rat model of chronic constriction injury, these rats were divided into 10 groups (10 rats in each group): the normal control, sham operation, chronic constriction injury, normal saline, morphine, miR-223, NLRP3, miR-223 + morphine, NLRP3 + morphine, and miR-223 + NLRP3 + morphine groups. The real-time quantitative polymerase chain reaction assay, Western blotting, and enzyme-linked immunosorbent assay were used for detecting the mRNA and protein expressions of NLRP3, apoptosis-associated speck-like protein, Caspase-1, Interleukin (IL)-1β, and IL-18 in sections of lumbar spinal cord. Immunohistochemistry was applied for detecting the positive rates of NLRP3, apoptosis-associated speck-like protein, Caspase-1, IL-1β, and IL-18. Results The paw withdrawal threshold and percentage maximum possible effect (%MPE) were higher in chronic constriction injury group when compared with the normal control and sham operation groups. Behavioral tests showed that compared with the chronic constriction injury and normal saline groups, the morphine and miR-223 + morphine groups showed obvious analgesic effects. Expressions of miR-223 in the miR-223, miR-223 + morphine, and miR-223 + NLRP3 + morphine were significantly higher than those in the chronic constriction injury, normal saline, and morphine groups. Compared with chronic constriction injury, normal saline and morphine groups, the mRNA and protein expressions of NLRP3, apoptosis-associated speck-like protein, Caspase-1, IL-1β, and IL-18 were significantly decreased in the miR-223 and miR-223 + morphine groups, while mRNA and protein expressions of NLRP3, apoptosis-associated speck-like protein, Caspase-1, IL-1β, and IL-18 were significantly increased in the NLRP3 and NLRP3 + morphine group. Conclusion Our study provides strong evidence that miR-223 could suppress the activities of NLRP3 inflammasomes (NLRP3, apoptosis-associated speck-like protein, and Caspase-1) to relieve morphine analgesic tolerance in rats by down-regulating NLRP3. PMID:28580822

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.

Severe Craniofacial Involvement due to Amniotic Band Sequence.

PubMed

Becerra-Solano, Luis Eduardo; Castañeda-Cisneros, Gema; Corona-Rivera, Jorge Roman; Díaz-Rodríguez, Manuel; Figuera, Luis Eduardo; López-Muñoz, Eunice; Nastasi-Catanese, José Antonio; Toscano-Flores, José Jesús; Ramírez-Dueñas, María de Lourdes; García-Ortíz, José Elias

2018-02-01

Disruptive amniotic band sequence (DABS) is a sporadic, non-familial disorder with unclear etiology. Diagnosis is based on clinical features because there is currently no reliable laboratory diagnostic tests. We describe six cases of DABS with severe craniofacial deformations, three with and three without classical constrictive limb deformation. The craniofacial deformities were delimited by peripheral sharply demarcated scarring. When a sharply demarcated linear disruptive craniofacial lesion is observed, DABS should be considered despite the absence of constrictive limb scarring.

[Expression of A-type atrial natriuretic peptide receptor in the kidneys of renovascular hypertension rats and its implication].

PubMed

Liu, Rong-Tao; Xiao, Jing; Guo, Hui-Ling; Qiu, Dun-Guo; Yin, Hua-Hu; Wang, Zheng-Rong

2005-11-01

To investigate the expression of A-type atrial natriuretic peptide receptor (ANPR-A) in the kidneys of renovascular hypertension rats and evaluate the significance of the expression. The rat model of renovascular hypertension was produced by constricting one lateral renal artery. After the renal artery being constricted for 4 weeks and 8 weeks, the systolic BP of rats was measured with a manometer using the tail-cuff method. Then, the expression of ANPR-A was respectively detected by immunohistochemical technique in the kidneys of the two-kidney, one-clip (2K1C) rats, and the expression level of ANPR-A was semi-quantitatively measured by Mias-2000 computer image analyzer. At 4 weeks after the artery-constricted operation,the expression of ANPR-A increased significantly in 2K1C hypertensive rat glomeruli and decreased significantly in renal tubules, compared with control (P<0.01), but there was no marked change in medullar collecting tubules. At 8 weeks after the artery-constricted operation, the expression of ANPR-A decreased significantly in 2K1C hypertensive rat renal tubules and medullar collecting tubules, compared with control (P<0.01); however, there was weak expression in glomeruli, and no statistically significant difference was seen when compared with control (P>0.05). The expression of ANPR-A decreased significantly in kidney tissues of renovascular

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.

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.

Low-dose thromboxane A2 receptor stimulation promotes closure of the rat ductus arteriosus with minimal adverse effects.

PubMed

Yokota, Tomohiro; Aida, Takashi; Ichikawa, Yasuhiro; Fujita, Takayuki; Yokoyama, Utako; Minamisawa, Susumu

2012-08-01

Patent ductus arteriosus (PDA) is a common life-threatening complication among premature infants. Although cyclooxygenase inhibitors are frequently used to treat PDA, as they inhibit the synthesis of prostaglandin E(2), the most potent vasodilator in the ductus arteriosus (DA), their efficacy is often limited. As thromboxane A(2) (TXA(2)) induces vascular contraction via the TXA(2) receptor (TP), we hypothesized that TP stimulation would promote DA closure. To measure the inner diameter of the vessels, a rapid whole-body freezing method was used. Injection of the selective TP agonists U46619 and I-BOP constricted the fetal DA at embryonic day 19 (e19) and e21 in a dose-dependent manner. Of note, U46619 also exerted a vasoconstrictive effect on two different types of postnatal PDA models: premature PDA and hypoxia-induced PDA. We also found that U46619 constricted the ex vivo DA ring to a greater extent than it constricted the ex vivo aorta. Furthermore, we found that U46619 at lower concentrations (up to 0.05 mg/g of body weight) had a minimal vasoconstrictive effect on other vessels and did not induce microthrombosis in the pulmonary capillary arteries. Low-dose TP stimulation constricts the DA with minimal adverse effects at least in rat neonates and our results could point to an alternative potent vasoconstrictor for PDA.

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.

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 retina might be responsible for this phenomenon.

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 number UMIN000016853. PMID:26423851

Retinal vessel diameters and reactivity in diabetes mellitus and/or cardiovascular disease.

PubMed

Heitmar, R; Lip, G Y H; Ryder, R E; Blann, A D

2017-04-26

Retinal vessel calibre and vascular dilation/constriction in response to flicker light provocation may provide a measure distinguishing patients suffering from diabetes mellitus and/or cardiovascular disease. One hundred and sixteen age and sex matched patients with diabetes mellitus (DM), cardiovascular disease (CVD) and both DM and CVD (DM + CVD) underwent systemic and intraocular pressure measurements. Retinal vessel calibres were assessed using a validated computer-based program to compute central retinal artery and vein equivalents (CRVE) from monochromatic retinal images. Vessel dilation and constriction responses to flicker light provocation were assessed by continuous retinal vessel diameter recordings. Plasma endothelial markers von Willebrand factor (vWf) and soluble E selectin (sEsel) were measured by ELISA. Retinal vessel calibres were comparable across groups but CRVE correlated significantly with disease duration in DM patients (r = 0.57, p < 0.001). Patients suffering DM only exhibited reduced arterial vasomotion at rest and reduced arterial constriction following flicker light induced vessel dilation compared to patients with CVD and those suffering both CVD + DM (p = 0.030). Patients suffering from CVD + DM exhibited significant differences between each flicker cycle in regards to arterial maximum constriction (p = 0.006) and time needed to reach arterial maximum dilation (p = 0.004), whereas the other two groups did not show such inconsistencies between individual flicker cycles. vWf was raised in CVD + DM compared to the other two groups (p ≤ 0.02), whilst sEsel was raised in CVD + DM compared to DM alone (p = 0.044). Dynamic retinal vascular calibres as obtained by continuous diameter measurements using flicker light provocation can reveal subtle differences between groups suffering from CVD with and without DM. This difference in reaction pattern and lack of arterial constriction in DM may provide a suitable marker to monitor progression.

Blast Trauma. The Effect on Hearing.

DTIC Science & Technology

1983-07-01

Reissner’ s menbrane was also removed. £he re-arning cochlea was then rapidly dehydrated in a cold graded ETOH series (50, 70, 80, 95, 100%). The... plasma zpze aet,’,r the eIBCs and the vessel wall. This could be interpreted as the r ’Lt of vessel constriction, of corpuscular rather than laminar blood...most likely explanation for the de.crease in plasma spuc-e. Constrictions and irregularities of the vessel lumen appear to be due to an increased

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.

Pseudomyopia in a patient with blocked ventriculo-peritoneal shunt--a case report.

PubMed

Voon, L W; Goh, K Y; Lim, T H; Tan, K K; Yong, V S

1997-03-01

Accommodative spasm usually encompasses a classical triad of pseudomyopia, esodeviation and pupillary constriction. Accommodative spasm is most often psychogenic in nature; however, it may be associated with other organic diseases of which a rare cause is that of intracranial catheter complications. We report a case of dorsal midbrain syndrome with pseudomyopia in a patient with a blocked ventriculo-peritoneal shunt inserted for aqueductal stenosis. Clinical presentation was unusual in this patient as pseudomyopia occurred with exodeviation and without pupillary constriction.

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.

Radiologically occult medulloblastoma with hydrocephalus: case report.

PubMed

Honma, Hirokuni; Ogiwara, Hideki

2017-09-01

There have been no reports of occult medulloblastoma nor noncommunicating hydrocephalus due to radiologically occult brain tumors. Herein, we report radiologically occult medulloblastoma with noncommunicating hydrocephalus. A 3-year-old boy presented with macrocephaly, visual field constriction, and papilledema. Neuroimagings showed enlargement of the ventricles without any mass lesions. The CT cisternography did not show influx of the contrast into the ventricles, which suggested local cerebrospinal fluid (CSF) circulatory disturbance at the outlet of the fourth ventricle. Due to possible obstructive nature of hydrocephalus, endoscopic third ventriculostomy (ETV) was performed. Three months after the ETV, he presented with repeated vomiting. Neuroimagings showed a 3-cm fourth ventricular mass with progressive hydrocephalus. Surgical resection was performed, which revealed the pathology was medulloblastoma. We report the case of radiologically occult medulloblastoma which was demonstrated radiologically in the follow-up period of ETV for noncommunicating hydrocephalus of uncertain etiology. This is the first description of a radiologically occult medulloblastoma and also the first description of an occult brain tumor with noncommunicating hydrocephalus. The occult brain tumor may be included in the etiology of hydrocephalus.

Inter-dependent apical microtubule and actin dynamics orchestrate centrosome retention and neuronal delamination

PubMed Central

Kasioulis, Ioannis

2017-01-01

Detachment of newborn neurons from the neuroepithelium is required for correct neuronal architecture and functional circuitry. This process, also known as delamination, involves adherens-junction disassembly and acto-myosin-mediated abscission, during which the centrosome is retained while apical/ciliary membranes are shed. Cell-biological mechanisms mediating delamination are, however, poorly understood. Using live-tissue and super-resolution imaging, we uncover a centrosome-nucleated wheel-like microtubule configuration, aligned with the apical actin cable and adherens-junctions within chick and mouse neuroepithelial cells. These microtubules maintain adherens-junctions while actin maintains microtubules, adherens-junctions and apical end-foot dimensions. During neuronal delamination, acto-myosin constriction generates a tunnel-like actin-microtubule configuration through which the centrosome translocates. This movement requires inter-dependent actin and microtubule activity, and we identify drebrin as a potential coordinator of these cytoskeletal dynamics. Furthermore, centrosome compromise revealed that this organelle is required for delamination. These findings identify new cytoskeletal configurations and regulatory relationships that orchestrate neuronal delamination and may inform mechanisms underlying pathological epithelial cell detachment. PMID:29058679

Pathological Studies of “Sudden Death Syndrome” in Broiler Chickens

PubMed Central

Ononiwu, J.C.; Thomson, R.G.; Carlson, H.C.; Julian, R.J.

1979-01-01

Sudden death syndrome usually occurs in heavy, fast-growing and healthy-looking broilers. Most of the affected birds are males. The characteristic necropsy changes are seen in well-fleshed broilers with edema and generalized pulmonary congestion, recently ingested feed in the crop and gizzard, distended intestine with creamy content and empty gall bladder. The liver and kidneys are slightly enlarged and the latter have patchy areas of subcapsular hemorrhage. The heart contains clotted blood in the atria but the ventricles are often empty and the left ventricle in particular assumes a hypertrophied appearance. Microscopic examination of heart muscle reveals degeneration of fibers, separation of cardiac muscle fibers by edema and infiltration of heterophils. The lungs have severe vascular congestion, inflammatory cell infiltration in the mucosa of the secondary bronchi and edema fluid in the tertiary bronchi and interlobular connective tissue. The liver has moderate bile duct hyperplasia, periportal hepatitis and mononuclear cell infiltration adjacent to bile ducts which possibly leads to bile duct constriction. The kidneys have subcapsular and parenchymatous hemorrhage. ImagesFIGURE 1.FIGURE 2. PMID:436100

Protective effect of fenspiride on the bronchi in rats with chronic obstructive pulmonary disease.

PubMed

Kuzubova, N A; Lebedeva, E S; Fedin, A N; Dvorakovskaya, I V; Titova, O N

2013-06-01

We studied the effect of a non-steroidal anti-inflammatory drug fenspiride on contractive activity of bronchial smooth muscles on the model of chronic obstructive pulmonary disease of rats induced by 60-day exposure to nitrogen dioxide. The administration of fenspiride during the acute stage of the disease (day 15) abolished the constricting effect of the pollutant on the bronchial smooth muscles. Dilatation effect of fenspiride in a low dose (0.15 mg/kg) was mediated by its interaction with nerve endings of bronchial capsaicin-sensitive nerve C-fibers. The interaction of drug with receptors of C-fibers prevented neurogenic inflammation, which was confirmed by the absence of structural changes in the lungs typical of this pathology. The broncholytic effect of fenspiride in a high dose (15 mg/kg) was mediated by not only afferent pathways, but also its direct relaxing action on smooth muscle cells. The observed anti-inflammatory and bronchodilatation effect of fenspiride in very low doses can be used for prevention of chronic obstructive pulmonary disease in risk-group patients contacting with aggressive environmental factors.

Contrasting effects of pseudoephedrine and papaverine in dextran sodium sulfate-induced colitis.

PubMed

Harris, Norman R; Specian, Robert D; Carter, Patsy R; Morgan, Georgia A

2008-03-01

Dextran sodium sulfate (DSS) induces submucosal arteriolar constriction that reduces blood flow to the intestine, and the relevance of this decrease in flow needs further investigation. In the present study we examined the effects of a vasoconstrictor (pseudoephedrine) and a vasodilator (papaverine) on the outcome of DSS-induced colitis. Mice were given DSS in drinking water for 6 days, with enemas on days 0, 1, 3, and 5 containing pseudoephedrine, papaverine, or no drug. At the conclusion of the 6-day protocol a disease activity index comprising weight loss, stool consistency, and rectal bleeding was evaluated, along with intravital microscopy observations of submucosal venular leukocyte and platelet adherence in the proximal colon and terminal ileum. Pseudoephedrine and papaverine had several contrasting effects on the outcome of DSS ingestion: pseudoephedrine induced the highest levels of weight loss, loose stools, venular platelet adherence, and overall disease activity index, while papaverine induced the highest levels of venular leukocyte adherence, but the lowest levels of rectal bleeding, loose stools, and overall disease activity index. The results suggest that vasoconstriction worsens the pathological consequences of DSS in the mouse model of colitis.

Macrophage Migration Inhibitory Factor Deletion Exacerbates Pressure Overload-Induced Cardiac Hypertrophy through Mitigating Autophagy

PubMed Central

Xu, Xihui; Hua, Yinan; Nair, Sreejayan; Bucala, Richard; Ren, Jun

2014-01-01

The proinflammatory cytokine macrophage migration inhibitory factor (MIF) has been shown to be cardioprotective in various pathological conditions. However, the underlying mechanisms still remain elusive. In this study, we revealed that MIF deficiency overtly exacerbated abdominal aorta constriction (AAC)-induced cardiac hypertrophy and contractile anomalies. MIF deficiency interrupted myocardial autophagy in hypertrophied hearts. Rapamycin administration mitigated the exacerbated hypertrophic responses in MIF−/− mice. Using the phenylephrine-induced hypertrophy in vitro model in H9C2 myoblasts, we confirmed that MIF governed activation of AMPK-mTOR-autophagy cascade. Confocal microscopic examination demonstrated that MIF depletion prevented phenylephrine-induced mitophagy in H9C2 myoblasts. Myocardial Parkin, an E3 ubiquitin ligase and a marker for mitophagy, was significantly upregulated following sustained pressure overload, the effect of which was prevented by MIF knockout. Moreover, our data exhibited that levels of MIF, AMPK activation and autophagy were elevated concurrently in human failing hearts. These data indicate that endogenous MIF regulates the mTOR signaling to activate autophagy to preserve cardiac geometry and protect against hypertrophic responses. PMID:24366076

Gallic acid attenuates pulmonary fibrosis in a mouse model of transverse aortic contraction-induced heart failure.

PubMed

Jin, Li; Piao, Zhe Hao; Sun, Simei; Liu, Bin; Ryu, Yuhee; Choi, Sin Young; Kim, Gwi Ran; Kim, Hyung-Seok; Kee, Hae Jin; Jeong, Myung Ho

2017-12-01

Gallic acid, a trihydroxybenzoic acid found in tea and other plants, attenuates cardiac hypertrophy, fibrosis, and hypertension in animal models. However, the role of gallic acid in heart failure remains unknown. In this study, we show that gallic acid administration prevents heart failure-induced pulmonary fibrosis. Heart failure induced in mice, 8weeks after transverse aortic constriction (TAC) surgery, was confirmed by echocardiography. Treatment for 2weeks with gallic acid but not furosemide prevented cardiac dysfunction in mice. Gallic acid significantly inhibited TAC-induced pathological changes in the lungs, such as increased lung mass, pulmonary fibrosis, and damaged alveolar morphology. It also decreased the expression of fibrosis-related genes, including collagen types I and III, fibronectin, connective tissue growth factor (CTGF), and phosphorylated Smad3. Further, it inhibited the expression of epithelial-mesenchymal transition (EMT)-related genes, such as N-cadherin, vimentin, E-cadherin, SNAI1, and TWIST1. We suggest that gallic acid has therapeutic potential for the treatment of heart failure-induced pulmonary fibrosis. Copyright © 2017 Elsevier Inc. All rights reserved.

Electrode support for gas arc welding torch having coaxial vision

NASA Technical Reports Server (NTRS)

Richardson, Richard W. (Inventor)

1987-01-01

An improved electrode mounting structure for a gas tungsten arc welding torch having a coaxial imaging system. The electrode mounting structure includes a support having a central hub and a plurality of spokes which extend from the hub generally radially with respect to the axis of the torch into supporting engagement with the interior walls of the torch. The spaces between the spokes are optical passages for transmission of light to form the image. A tubular collet holder is threadedly engaged at its upper end to the hub and extends downwardly toward the open end of the torch. The collet holder has an inwardly tapering constriction near its lower end. An electrode-retaining, tubular collet is mounted within the collet holder and has a longitudinally split and tapered end seating against the tapered constriction. A spring seats against the upper end of the collet and forces the split end against the tapered constriction to wedge the split end radially inwardly to grip the electrode within the collet.

Loss of Gα12/13 exacerbates apical area dependence of actomyosin contractility

PubMed Central

Xie, Shicong; Mason, Frank M.; Martin, Adam C.

2016-01-01

During development, coordinated cell shape changes alter tissue shape. In the Drosophila ventral furrow and other epithelia, apical constriction of hundreds of epithelial cells folds the tissue. Genes in the Gα12/13 pathway coordinate collective apical constriction, but the mechanism of coordination is poorly understood. Coupling live-cell imaging with a computational approach to identify contractile events, we discovered that differences in constriction behavior are biased by initial cell shape. Disrupting Gα12/13 exacerbates this relationship. Larger apical area is associated with delayed initiation of contractile pulses, lower apical E-cadherin and F-actin levels, and aberrantly mobile Rho-kinase structures. Our results suggest that loss of Gα12/13 disrupts apical actin cortex organization and pulse initiation in a size-dependent manner. We propose that Gα12/13 robustly organizes the apical cortex despite variation in apical area to ensure the timely initiation of contractile pulses in a tissue with heterogeneity in starting cell shape. PMID:27489340

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.

Extrahepatic biliary duct obstruction as a result of involuntary transcavitary implantation of hair in a cat

PubMed Central

Linton, Michael; Buffa, Eugene; Simon, Adrian; Ashton, Julie; McGregor, Ross; Foster, Darren J

2015-01-01

Case summary A 4-year-old male neutered domestic shorthair cat was referred for investigation of jaundice. The cat had a recent history of a skin laceration repair following trauma. Sequential serum biochemistry demonstrated increasing plasma bilirubin concentrations; abdominal ultrasonography revealed ongoing pancreatitis and apparent extrahepatic obstruction of the common bile duct. Exploratory laparotomy identified constriction of the common bile duct with foreign material (cat hair). The constricting band of hair was removed surgically; cholecystoduodenostomy was performed. Postsurgical quality of life is excellent with chronic treatment of tylosin, omeprazole and ursodeoxycholic acid. Relevance and novel information To our knowledge, this is the first reported case of extrahepatic biliary duct obstruction resulting from the intra-abdominal migration of a foreign body, in this case, hair shafts. The mechanism by which this occurred was likely a combination of physical constriction by the hair shafts and subsequent foreign body reaction surrounding this. This should be included in the differential diagnosis of a cat with jaundice. PMID:28491390

Phase transition solutions in geometrically constrained magnetic domain wall models

NASA Astrophysics Data System (ADS)

Chen, Shouxin; Yang, Yisong

2010-02-01

Recent work on magnetic phase transition in nanoscale systems indicates that new physical phenomena, in particular, the Bloch wall width narrowing, arise as a consequence of geometrical confinement of magnetization and leads to the introduction of geometrically constrained domain wall models. In this paper, we present a systematic mathematical analysis on the existence of the solutions of the basic governing equations in such domain wall models. We show that, when the cross section of the geometric constriction is a simple step function, the solutions may be obtained by minimizing the domain wall energy over the constriction and solving the Bogomol'nyi equation outside the constriction. When the cross section and potential density are both even, we establish the existence of an odd domain wall solution realizing the phase transition process between two adjacent domain phases. When the cross section satisfies a certain integrability condition, we prove that a domain wall solution always exists which links two arbitrarily designated domain phases.

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

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.

Tunable transmission of quantum Hall edge channels with full degeneracy lifting in split-gated graphene devices.

PubMed

Zimmermann, Katrin; Jordan, Anna; Gay, Frédéric; Watanabe, Kenji; Taniguchi, Takashi; Han, Zheng; Bouchiat, Vincent; Sellier, Hermann; Sacépé, Benjamin

2017-04-13

Charge carriers in the quantum Hall regime propagate via one-dimensional conducting channels that form along the edges of a two-dimensional electron gas. Controlling their transmission through a gate-tunable constriction, also called quantum point contact, is fundamental for many coherent transport experiments. However, in graphene, tailoring a constriction with electrostatic gates remains challenging due to the formation of p-n junctions below gate electrodes along which electron and hole edge channels co-propagate and mix, short circuiting the constriction. Here we show that this electron-hole mixing is drastically reduced in high-mobility graphene van der Waals heterostructures thanks to the full degeneracy lifting of the Landau levels, enabling quantum point contact operation with full channel pinch-off. We demonstrate gate-tunable selective transmission of integer and fractional quantum Hall edge channels through the quantum point contact. This gate control of edge channels opens the door to quantum Hall interferometry and electron quantum optics experiments in the integer and fractional quantum Hall regimes of graphene.

Experimental observation of edge transport in graphene nanostructures

NASA Astrophysics Data System (ADS)

Kinikar, Amogh; Sai, T. Phanindra; Bhattacharyya, Semonti; Agarwala, Adhip; Biswas, Tathagata; Sarker, Sanjoy K.; Krishnamurthy, H. R.; Jain, Manish; Shenoy, Vijay B.; Ghosh, Arindam

The zizzag edges of graphene, whether single or few layers, host zero energy gapless states and are perfect 1D ballistic conductors. Conclusive observations of electrical conduction through edge states has been elusive. We report the observation of edge bound transport in atomic-scale constrictions of single and multilayer suspended graphene created stochastically by nanomechanical exfoliation of graphite. We observe that the conductance is quantized in near multiples of e2/h. Non-equilibrium transport shows a split zero bias anomaly and, the magneto-conductance is hysteretic; indicating that the electron transport is through spin polarized edge states in the presence of electron-electron interaction. Atomic force microscope scans on the graphite surface post exfoliation reveal that the final constriction is usually a single layer graphene with a constricting angle of 30o. Tearing along crystallographic angles suggests the tears occur along zigzag and armchair configurations with high fidelity of the edge morphology. We acknowledge the financial support from the DST, Government of India. SS acknowledges support from the NSF (DMR-1508680).

Fluid sampling system

DOEpatents

Houck, Edward D.

1994-01-01

An fluid sampling system allows sampling of radioactive liquid without spillage. A feed tank is connected to a liquid transfer jet powered by a pumping chamber pressurized by compressed air. The liquid is pumped upwardly into a sampling jet of a venturi design having a lumen with an inlet, an outlet, a constricted middle portion, and a port located above the constricted middle portion. The liquid is passed under pressure through the constricted portion causing its velocity to increase and its pressure to decreased, thereby preventing liquid from escaping. A septum sealing the port can be pierced by a two pointed hollow needle leading into a sample bottle also sealed by a pierceable septum affixed to one end. The bottle is evacuated by flow through the sample jet, cyclic variation in the sampler jet pressure periodically leaves the evacuated bottle with lower pressure than that of the port, thus causing solution to pass into the bottle. The remaining solution in the system is returned to the feed tank via a holding tank.

Fluid sampling system

DOEpatents

Houck, E.D.

1994-10-11

An fluid sampling system allows sampling of radioactive liquid without spillage. A feed tank is connected to a liquid transfer jet powered by a pumping chamber pressurized by compressed air. The liquid is pumped upwardly into a sampling jet of a venturi design having a lumen with an inlet, an outlet, a constricted middle portion, and a port located above the constricted middle portion. The liquid is passed under pressure through the constricted portion causing its velocity to increase and its pressure to be decreased, thereby preventing liquid from escaping. A septum sealing the port can be pierced by a two pointed hollow needle leading into a sample bottle also sealed by a pierceable septum affixed to one end. The bottle is evacuated by flow through the sample jet, cyclic variation in the sampler jet pressure periodically leaves the evacuated bottle with lower pressure than that of the port, thus causing solution to pass into the bottle. The remaining solution in the system is returned to the feed tank via a holding tank. 4 figs.

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

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.

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

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.

Characterizing deformability and surface friction of cancer cells

PubMed Central

Byun, Sangwon; Son, Sungmin; Amodei, Dario; Cermak, Nathan; Shaw, Josephine; Kang, Joon Ho; Hecht, Vivian C.; Winslow, Monte M.; Jacks, Tyler; Mallick, Parag; Manalis, Scott R.

2013-01-01

Metastasis requires the penetration of cancer cells through tight spaces, which is mediated by the physical properties of the cells as well as their interactions with the confined environment. Various microfluidic approaches have been devised to mimic traversal in vitro by measuring the time required for cells to pass through a constriction. Although a cell’s passage time is expected to depend on its deformability, measurements from existing approaches are confounded by a cell's size and its frictional properties with the channel wall. Here, we introduce a device that enables the precise measurement of (i) the size of a single cell, given by its buoyant mass, (ii) the velocity of the cell entering a constricted microchannel (entry velocity), and (iii) the velocity of the cell as it transits through the constriction (transit velocity). Changing the deformability of the cell by perturbing its cytoskeleton primarily alters the entry velocity, whereas changing the surface friction by immobilizing positive charges on the constriction's walls primarily alters the transit velocity, indicating that these parameters can give insight into the factors affecting the passage of each cell. When accounting for cell buoyant mass, we find that cells possessing higher metastatic potential exhibit faster entry velocities than cells with lower metastatic potential. We additionally find that some cell types with higher metastatic potential exhibit greater than expected changes in transit velocities, suggesting that not only the increased deformability but reduced friction may be a factor in enabling invasive cancer cells to efficiently squeeze through tight spaces. PMID:23610435

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.

Functional ET(A)-ET(B) Receptor Cross-talk in Basilar Artery In Situ From ET(B) Receptor Deficient Rats.

PubMed

Yoon, SeongHun; Gariepy, Cheryl E; Yanagisawa, Masashi; Zuccarello, Mario; Rapoport, Robert M

2016-03-01

The role of endothelin (ET)(A)-ET(B) receptor cross-talk in limiting the ET(A) receptor antagonist inhibition of ET-1 constriction is revealed by the partial or complete dependency of the ET(A) receptor antagonist inhibition on functional removal of the ET(B) receptor. Although functional removal of the ET(B) receptor is generally accomplished with ET(B) receptor antagonist, a novel approach using rats containing a naturally occurring deletion mutation in the ET(B) receptor [rescued "spotting lethal" (sl) rats; ET(B)(sl/sl)] demonstrated increased ET(A) receptor antagonist inhibition of ET-1 constriction in vena cava. We investigated whether this deletion mutation was also sufficient to remove the ET(B) receptor dependency of the ET(A) receptor antagonist inhibition of ET-1 constriction in the basilar artery. Consistent with previous reports, ET-1 plasma levels were elevated in ET(B)(sl/sl) as compared with ET(B)(+/+) rats. ET(B) receptor antagonist failed to relax the ET-1 constricted basilar artery from ET(B)(+/+) and ET(B)(sl/sl) rats. Relaxation to combined ET(A) and ET(B) receptor antagonist was greater than relaxation to ET(A) receptor antagonist in the basilar artery from ET(B)(+/+) and, unexpectedly, ET(B)(sl/sl) rats. These findings confirm the presence of ET(A)-ET(B) receptor cross-talk in the basilar artery. We speculate that mutant ET(B) receptor expression produced by alternative splicing may be sufficient to allow cross-talk.

Cold stress accentuates pressure overload-induced cardiac hypertrophy and contractile dysfunction: role of TRPV1/AMPK-mediated autophagy.

PubMed

Lu, Songhe; Xu, Dezhong

2013-12-06

Severe cold exposure and pressure overload are both known to prompt oxidative stress and pathological alterations in the heart although the interplay between the two remains elusive. Transient receptor potential vanilloid 1 (TRPV1) is a nonselective cation channel activated in response to a variety of exogenous and endogenous physical and chemical stimuli including heat and capsaicin. The aim of this study was to examine the impact of cold exposure on pressure overload-induced cardiac pathological changes and the mechanism involved. Adult male C57 mice were subjected to abdominal aortic constriction (AAC) prior to exposure to cold temperature (4 °C) for 4 weeks. Cardiac geometry and function, levels of TRPV1, mitochondrial, and autophagy-associated proteins including AMPK, mTOR, LC3B, and P62 were evaluated. Sustained cold stress triggered cardiac hypertrophy, compromised depressed myocardial contractile capacity including lessened fractional shortening, peak shortening, and maximal velocity of shortening/relengthening, enhanced ROS production, and mitochondrial injury, the effects of which were negated by the TRPV1 antagonist SB366791. Western blot analysis revealed upregulated TRPV1 level and AMPK phosphorylation, enhanced ratio of LC3II/LC3I, and downregulated P62 following cold exposure. Cold exposure significantly augmented AAC-induced changes in TRPV1, phosphorylation of AMPK, LC3 isoform switch, and p62, the effects of which were negated by SB366791. In summary, these data suggest that cold exposure accentuates pressure overload-induced cardiac hypertrophy and contractile defect possibly through a TRPV1 and autophagy-dependent mechanism. Copyright © 2013. Published by Elsevier 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 between patients with constrictive pericarditis and those with cardiomyopathy. The presence of diseased thickened pericardium does not by itself impart impairment of ventricular diastolic function. Thus, definitive diagnosis of constrictive pericarditis requires demonstration of both abnormal anatomy and physiology.

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 (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Three new and a known species of the genus Proleptonchus Lordello, 1955 (Nematoda: Leptonchidae) with a diagnostic compendium of the genus.

PubMed

Ahad, Sumaya; Ahmad, Wasim

2016-11-09

This paper deals with the description of three new and one known species of the genus Proleptonchus Lordello, 1955. Proleptonchus kazirangus n. sp. from Kaziranga National Park, India is characterized by having 1.08-1.45 mm long body; cap-like, offset, lip region; 7-8 µm long odontostyle and 10-12 µm long odontophore; short, pear-shaped pharyngeal bulb offset by a constriction, occupying about 18-21% of total neck length; female genital system mono-prodelphic; pars dilatata uteri with distinctly sclerotized central lumen containing refringent apophyses; posterior uterine sac 78-112 µm long, with sac-like structure representing a rudimentary oviduct; transverse vulva, short, rounded-conoid tail and males with 31-33 µm long spicules, lateral guiding pieces and seven, regularly spaced ventromedian supplements. P. prerectus n. sp. from Japan is characterized by having 1.18-1.43 mm long body; lip region cap-like, offset by a slight constriction; odontostyle 8 µm, odontophore 9-10 µm; short cylindroid basal bulb offset by a constriction, occupying about 16-20% of total neck length; female genital system mono-prodelphic; pars dilatata uteri with sclerotized refringent apophyses; posterior uterine sac small, 27-36 µm; transverse vulva; a prerectal chamber and short, rounded-hemispheroid tail. P. japonicus n. sp. also from Japan is characterized by having 0.91-1.04 mm long body; lip region cap-like, set off by a slight constriction; odontostyle 5 µm and odontophore 10-11 µm long; pharynx consists of a very slender, non-muscular anterior part, separated from pyriform basal bulb by a constriction, with thickened lumen in posterior region, occupying about 18-20% of total neck length; female genital system mono-prodelphic; posterior uterine sac small, 20-24 µm long; transverse vulva and short, rounded-conoid tail. P. shamimi Bajaj & Bhatti, 1980 is redescribed and its relationship with closely related species is discussed. A diagnostic compendium of all the valid species of Proleptonchus is also provided.

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.

A hydrophobic gate in an ion channel: the closed state of the nicotinic acetylcholine receptor

NASA Astrophysics Data System (ADS)

Beckstein, Oliver; Sansom, Mark S. P.

2006-06-01

The nicotinic acetylcholine receptor (nAChR) is the prototypic member of the 'Cys-loop' superfamily of ligand-gated ion channels which mediate synaptic neurotransmission, and whose other members include receptors for glycine, γ-aminobutyric acid and serotonin. Cryo-electron microscopy has yielded a three-dimensional structure of the nAChR in its closed state. However, the exact nature and location of the channel gate remains uncertain. Although the transmembrane pore is constricted close to its center, it is not completely occluded. Rather, the pore has a central hydrophobic zone of radius about 3 Å. Model calculations suggest that such a constriction may form a hydrophobic gate, preventing movement of ions through a channel. We present a detailed and quantitative simulation study of the hydrophobic gating model of the nicotinic receptor, in order to fully evaluate this hypothesis. We demonstrate that the hydrophobic constriction of the nAChR pore indeed forms a closed gate. Potential of mean force (PMF) calculations reveal that the constriction presents a barrier of height about 10 kT to the permeation of sodium ions, placing an upper bound on the closed channel conductance of 0.3 pS. Thus, a 3 Å radius hydrophobic pore can form a functional barrier to the permeation of a 1 Å radius Na+ ion. Using a united-atom force field for the protein instead of an all-atom one retains the qualitative features but results in differing conductances, showing that the PMF is sensitive to the detailed molecular interactions.

Distinct cytoskeleton populations and extensive crosstalk control Ciona notochord tubulogenesis.

PubMed

Dong, Bo; Deng, Wei; Jiang, Di

2011-04-01

Cell elongation is a fundamental process that allows cells and tissues to adopt new shapes and functions. During notochord tubulogenesis in the ascidian Ciona intestinalis, a dramatic elongation of individual cells takes place that lengthens the notochord and, consequently, the entire embryo. We find a novel dynamic actin- and non-muscle myosin II-containing constriction midway along the anteroposterior aspect of each notochord cell during this process. Both actin polymerization and myosin II activity are required for the constriction and cell elongation. Discontinuous localization of myosin II in the constriction indicates that the actomyosin network produces local contractions along the circumference. This reveals basal constriction by the actomyosin network as a novel mechanism for cell elongation. Following elongation, the notochord cells undergo a mesenchymal-epithelial transition and form two apical domains at opposite ends. Extracellular lumens then form at the apical surfaces. We show that cortical actin and Ciona ezrin/radixin/moesin (ERM) are essential for lumen formation and that a polarized network of microtubules, which contributes to lumen development, forms in an actin-dependent manner at the apical cortex. Later in notochord tubulogenesis, when notochord cells initiate a bi-directional crawling movement on the notochordal sheath, the microtubule network rotates 90° and becomes organized as parallel bundles extending towards the leading edges of tractive lamellipodia. This process is required for the correct organization of actin-based protrusions and subsequent lumen coalescence. In summary, we establish the contribution of the actomyosin and microtubule networks to notochord tubulogenesis and reveal extensive crosstalk and regulation between these two cytoskeleton components.

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.

Lattice-like collagen fiber meshwork in the iris stroma of the cat: a possible mechanism to generate the tension directed towards the iris root which is required for pupillary dilatation in the sympathectomized eye.

PubMed

Sakuraba, M; Yun, S; Ichinohe, N; Yonekura, H; Shoumura, K

1999-10-01

NaOH digestion technique for collagen fiber dissection and scanning electron microscopy demonstrated a lattice-like meshwork in the anterior surface of the iris stroma of the cat. The mesh threads were made of collagen fibril bundles. In the constricted pupil, the meshes were square to rhomboid with the diagonals in the direction of the radius or circumference of the iris. In the dilated pupil, however, the meshes were strongly flattened rhomboid or ellipse with a longer diagnoal or axis in the circumferential direction. At the mesh corners facing the pupillary margin or the iris root, the collagen fibril bundles were strongly bent in the iris of the constricted pupil, while they were almost straight or slightly wavy in the iris of the dilated pupil. Accumulation of elasticity tension generated by this small distortion of the iris-mesh threads in the constricted pupil was considered to generate a tension directed towards the iris root, which is required for pupillary dilatation in the sympathectomized eye. On the posterior surface of the iris stroma, numerous thin pleats tightly woven with collagen fibrils traversed straightway through the radial length of the ciliary zone of the iris in both constricted and dilated pupils. The structural changes of these pleats in miosis and mydriasis were very small compared with the meshwork of the anterior aspect of the iris. Therefore, they were considered to work mainly as an iris skeleton.

Ion-binding properties of a K+ channel selectivity filter in different conformations.

PubMed

Liu, Shian; Focke, Paul J; Matulef, Kimberly; Bian, Xuelin; Moënne-Loccoz, Pierre; Valiyaveetil, Francis I; Lockless, Steve W

2015-12-08

K(+) channels are membrane proteins that selectively conduct K(+) ions across lipid bilayers. Many voltage-gated K(+) (KV) channels contain two gates, one at the bundle crossing on the intracellular side of the membrane and another in the selectivity filter. The gate at the bundle crossing is responsible for channel opening in response to a voltage stimulus, whereas the gate at the selectivity filter is responsible for C-type inactivation. Together, these regions determine when the channel conducts ions. The K(+) channel from Streptomyces lividians (KcsA) undergoes an inactivation process that is functionally similar to KV channels, which has led to its use as a practical system to study inactivation. Crystal structures of KcsA channels with an open intracellular gate revealed a selectivity filter in a constricted conformation similar to the structure observed in closed KcsA containing only Na(+) or low [K(+)]. However, recent work using a semisynthetic channel that is unable to adopt a constricted filter but inactivates like WT channels challenges this idea. In this study, we measured the equilibrium ion-binding properties of channels with conductive, inactivated, and constricted filters using isothermal titration calorimetry (ITC). EPR spectroscopy was used to determine the state of the intracellular gate of the channel, which we found can depend on the presence or absence of a lipid bilayer. Overall, we discovered that K(+) ion binding to channels with an inactivated or conductive selectivity filter is different from K(+) ion binding to channels with a constricted filter, suggesting that the structures of these channels are different.

Visualization of Membrane Pore in Live Cells Reveals a Dynamic-Pore Theory Governing Fusion and Endocytosis.

PubMed

Shin, Wonchul; Ge, Lihao; Arpino, Gianvito; Villarreal, Seth A; Hamid, Edaeni; Liu, Huisheng; Zhao, Wei-Dong; Wen, Peter J; Chiang, Hsueh-Cheng; Wu, Ling-Gang

2018-05-03

Fusion is thought to open a pore to release vesicular cargoes vital for many biological processes, including exocytosis, intracellular trafficking, fertilization, and viral entry. However, fusion pores have not been observed and thus proved in live cells. Its regulatory mechanisms and functions remain poorly understood. With super-resolution STED microscopy, we observed dynamic fusion pore behaviors in live (neuroendocrine) cells, including opening, expansion, constriction, and closure, where pore size may vary between 0 and 490 nm within 26 milliseconds to seconds (vesicle size: 180-720 nm). These pore dynamics crucially determine the efficiency of vesicular cargo release and vesicle retrieval. They are generated by competition between pore expansion and constriction. Pharmacology and mutation experiments suggest that expansion and constriction are mediated by F-actin-dependent membrane tension and calcium/dynamin, respectively. These findings provide the missing live-cell evidence, proving the fusion-pore hypothesis, and establish a live-cell dynamic-pore theory accounting for fusion, fission, and their regulation. Published by Elsevier Inc.

A Coincidence Detection Mechanism Controls PX-BAR Domain-Mediated Endocytic Membrane Remodeling via an Allosteric Structural Switch.

PubMed

Lo, Wen-Ting; Vujičić Žagar, Andreja; Gerth, Fabian; Lehmann, Martin; Puchkov, Dymtro; Krylova, Oxana; Freund, Christian; Scapozza, Leonardo; Vadas, Oscar; Haucke, Volker

2017-11-20

Clathrin-mediated endocytosis occurs by bending and remodeling of the membrane underneath the coat. Bin-amphiphysin-rvs (BAR) domain proteins are crucial for endocytic membrane remodeling, but how their activity is spatiotemporally controlled is largely unknown. We demonstrate that the membrane remodeling activity of sorting nexin 9 (SNX9), a late-acting endocytic PX-BAR domain protein required for constriction of U-shaped endocytic intermediates, is controlled by an allosteric structural switch involving coincident detection of the clathrin adaptor AP2 and phosphatidylinositol-3,4-bisphosphate (PI(3,4)P 2 ) at endocytic sites. Structural, biochemical, and cell biological data show that SNX9 is autoinhibited in solution. Binding to PI(3,4)P 2 via its PX-BAR domain, and concomitant association with AP2 via sequences in the linker region, releases SNX9 autoinhibitory contacts to enable membrane constriction. Our results reveal a mechanism for restricting the latent membrane remodeling activity of BAR domain proteins to allow spatiotemporal coupling of membrane constriction to the progression of the endocytic pathway. Copyright © 2017 Elsevier Inc. All rights reserved.

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

[Cytocompatibility of Co-Cr ceramic alloys after recasting].

PubMed

Hu, Yu-Feng; Jin, Wen-Zhong

2017-06-01

To study the correlation between apical foramen area and accuracy of PropexII electronic apex locator under destroyed apical constriction. Forty extracted teeth with single straight root canal were ground down 1 mm in the root tip and placed in 2% liquid agar gel injected into Castro model. The length of root canal was measured by PropexII electronic apex locator. The difference (L) between the electronic length (LP) and actual length was calculated. Imaging of apical foramen was recorded under microscope and apical foramen area (S) was measured by image processing software Photoshop CS. SPSS 22.0 software package was used to analyze the linear correlation and regression. With ±0.5 mm as the allowable range, all value of L was positive. The precise rate of PropexII was 52.5% when apical constriction was destroyed. There was a linear relationship between S and L (S=0.04+0.11×L，R=0.903）. The accuracy decreases when apical constriction is destroyed. The accuracy is worse when the apical foramen area is larger.

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.

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.

Marked Increase in Flow Velocities During Deep Expiration: A Duplex Doppler Sign of Celiac Artery Compression Syndrome

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

Erden, Ayse; Yurdakul, Mehmet; Cumhur, Turhan

1999-07-15

Symptoms of chronic mesenteric ischemia develop when the celiac artery is constricted by the median arcuate ligament of the diaphragm. Lateral aortography is the primary modality for diagnosing ligamentous compression of the celiac artery. However, duplex Doppler sonography performed during deep expiration can cause a marked increase in flow velocities at the compressed region of the celiac artery and suggest the diagnosis of celiac arterial constriction due to the diaphragmatic ligament. RID='''' ID='''' Correspondence to: A. Erden, M.D., Hafta sokak. 23/6, Gaziosmanpasa, 06700 Ankara, Turkey.

Chemical potential fluctuations in topological insulator (Bi0.5Sb0.5)2Te3-films visualized by photocurrent spectroscopy

NASA Astrophysics Data System (ADS)

Kastl, Christoph; Seifert, Paul; He, Xiaoyue; Wu, Kehui; Li, Yongqing; Holleitner, Alexander

2015-06-01

We investigate the photocurrent properties of the topological insulator (Bi0.5Sb0.5)2Te3 on SrTiO3-substrates. We find reproducible, submicron photocurrent patterns generated by long-range chemical potential fluctuations, occurring predominantly at the topological insulator/substrate interface. We fabricate nano-plowed constrictions which comprise single potential fluctuations. Hereby, we can quantify the magnitude of the disorder potential to be in the meV range. The results further suggest a dominating photo-thermoelectric current generated in the surface states in such nanoscale constrictions.

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, constriction of the chest wall was found in only 3 of the 34 patients in the preoperative group. The severity of constriction (as graded by the spline model) also increased in the postoperative group. The growth of the chest wall was restricted after placement of the Nuss bar for PE correction. Long-term follow-up of chest wall growth is needed to clarify whether such constriction resolves with time. Georg Thieme Verlag KG Stuttgart · New York.

Neural Control of the Cardiovascular System in Space

NASA Technical Reports Server (NTRS)

Levine, Benjamin D.; Pawelczyk, James A.; Zuckerman, Julie; Zhang, Rong; Fu, Qi; Iwasaki, Kenichi; Ray, Chet; Blomqvist, C. Gunnar; Lane, Lynda D.; Giller, Cole A.

2003-01-01

During the acute transition from lying supine to standing upright, a large volume of blood suddenly moves from the chest into the legs. To prevent fainting, the blood pressure control system senses this change immediately, and rapidly adjusts flow (by increasing heart rate) and resistance to flow (by constricting the blood vessels) to restore blood pressure and maintain brain blood flow. If this system is inadequate, the brain has a backup plan. Blood vessels in the brain can adjust their diameter to keep blood flow constant. If blood pressure drops, the brain blood vessels dilate; if blood pressure increases, the brain blood vessels constrict. This process, which is called autoregulation, allows the brain to maintain a steady stream of oxygen, even when blood pressure changes. We examined what changes in the blood pressure control system or cerebral autoregulation contribute to the blood pressure control problems seen after spaceflight. We asked: (1) does the adaptation to spaceflight cause an adaptation in the blood pressure control system that impairs the ability of the system to constrict blood vessels on return to Earth?; (2) if such a defect exists, could we pinpoint the neural pathways involved?; and (3) does cerebral autoregulation become abnormal during spaceflight, impairing the body s ability to maintain constant brain blood flow when standing upright on Earth? We stressed the blood pressure control system using lower body negative pressure, upright tilt, handgrip exercise, and cold stimulation of the hand. Standard cardiovascular parameters were measured along with sympathetic nerve activity (the nerve activity causing blood vessels to constrict) and brain blood flow. We confirmed that the primary cardiovascular effect of spaceflight was a postflight reduction in upright stroke volume (the amount of blood the heart pumps per beat). Heart rate increased appropriately for the reduction in stroke volume, thereby showing that changes in heart rate regulation alone cannot be responsible for orthostatic hypotension after spaceflight. All of the astronauts in our study had an increase in sympathetic nerve activity during upright tilting on Earth postflight. This increase was well calibrated for the reduction in stroke volume induced by the upright posture. The results obtained from stimulating the sympathetic nervous system using handgrip exercise or cold stress were also entirely normal during and after spaceflight. No astronaut had reduced cerebral blood flow during upright tilt, and cerebral autoregulation was normal or even enhanced inflight. These experiments show that the cardiovascular adaptation to spaceflight does not lead to a defect in the regulation of blood vessel constriction via sympathetic nerve activity. In addition, cerebral autoregulation is well-maintained. It is possible that despite the increased sympathetic nerve activity, blood vessels did not respond with a greater degree of constriction than occurred preflight, possibly uncovering a limit of vasoconstrictor reserve.

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.

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 frequency dielectrophoresis provides practical uses for integrating the concentration module with a portable biosensing system.

Classification of Newborn Ear Malformations and their Treatment with the EarWell Infant Ear Correction System.

PubMed

Daniali, Lily N; Rezzadeh, Kameron; Shell, Cheryl; Trovato, Matthew; Ha, Richard; Byrd, H Steve

2017-03-01

A single practice's treatment protocol and outcomes following molding therapy on newborn ear deformations and malformations with the EarWell Infant Ear Correction System were reviewed. A classification system for grading the severity of constricted ear malformations was created on the basis of anatomical findings. A retrospective chart/photograph review of a consecutive series of infants treated with the EarWell System from 2011 to 2014 was undertaken. The infants were placed in either deformation or malformation groups. Three classes of malformation were identified. Data regarding treatment induction, duration of treatment, and quality of outcome were collected for all study patients. One hundred seventy-five infant ear malformations and 303 infant ear deformities were treated with the EarWell System. The average age at initiation of treatment was 12 days; the mean duration of treatment was 37 days. An average of six office visits was required. Treated malformations included constricted ears [172 ears (98 percent)] and cryptotia [three ears (2 percent)]. Cup ear (34 ears) was considered a constricted malformation, in contrast to the prominent ear deformity. Constricted ears were assigned to one of three classes, with each subsequent class indicating increasing severity: class I, 77 ears (45 percent); class II, 81 ears (47 percent); and class III, 14 ears (8 percent). Molding therapy with the EarWell System reduced the severity by an average of 1.2 points (p < 0.01). Complications included minor superficial excoriations and abrasions. The EarWell System was shown to be effective in eliminating or reducing the need for surgery in all but the most severe malformations. Therapeutic, IV.

Centromeres Off the Hook: Massive Changes in Centromere Size and Structure Following Duplication of CenH3 Gene in Fabeae Species

PubMed Central

Neumann, Pavel; Pavlíková, Zuzana; Koblížková, Andrea; Fuková, Iva; Jedličková, Veronika; Novák, Petr; Macas, Jiří

2015-01-01

In most eukaryotes, centromere is determined by the presence of the centromere-specific histone variant CenH3. Two types of chromosome morphology are generally recognized with respect to centromere organization. Monocentric chromosomes possess a single CenH3-containing domain in primary constriction, whereas holocentric chromosomes lack the primary constriction and display dispersed distribution of CenH3. Recently, metapolycentric chromosomes have been reported in Pisum sativum, representing an intermediate type of centromere organization characterized by multiple CenH3-containing domains distributed across large parts of chromosomes that still form a single constriction. In this work, we show that this type of centromere is also found in other Pisum and closely related Lathyrus species, whereas Vicia and Lens genera, which belong to the same legume tribe Fabeae, possess only monocentric chromosomes. We observed extensive variability in the size of primary constriction and the arrangement of CenH3 domains both between and within individual Pisum and Lathyrus species, with no obvious correlation to genome or chromosome size. Search for CenH3 gene sequences revealed two paralogous variants, CenH3-1 and CenH3-2, which originated from a duplication event in the common ancestor of Fabeae species. The CenH3-1 gene was subsequently lost or silenced in the lineage leading to Vicia and Lens, whereas both genes are retained in Pisum and Lathyrus. Both of these genes appear to have evolved under purifying selection and produce functional CenH3 proteins which are fully colocalized. The findings described here provide the first evidence for a highly dynamic centromere structure within a group of closely related species, challenging previous concepts of centromere evolution. PMID:25771197

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

Milrinone Relaxes Pulmonary Veins in Guinea Pigs and Humans

PubMed Central

Rieg, Annette D.; Suleiman, Said; Perez-Bouza, Alberto; Braunschweig, Till; Spillner, Jan W.; Schröder, Thomas; Verjans, Eva; Schälte, Gereon; Rossaint, Rolf; Uhlig, Stefan; Martin, Christian

2014-01-01

Introduction The phosphodiesterase-III inhibitor milrinone improves ventricular contractility, relaxes pulmonary arteries and reduces right ventricular afterload. Thus, it is used to treat heart failure and pulmonary hypertension (PH). However, its action on pulmonary veins (PVs) is not defined, although particularly PH due to left heart disease primarily affects the pulmonary venous bed. We examined milrinone-induced relaxation in PVs from guinea pigs (GPs) and humans. Material and Methods Precision-cut lung slices (PCLS) were prepared from GPs or from patients undergoing lobectomy. Milrinone-induced relaxation was studied by videomicroscopy in naïve PVs and in PVs pre-constricted with the ETA-receptor agonist BP0104. Baseline luminal area was defined as 100%. Intracellular cAMP was measured by ELISA and milrinone-induced changes of segmental vascular resistances were studied in the GP isolated perfused lung (IPL). Results In the IPL (GP), milrinone (10 µM) lowered the postcapillary resistance of pre-constricted vessels. In PCLS (GP), milrinone relaxed naïve and pre-constricted PVs (120%) and this relaxation was attenuated by inhibition of protein kinase G (KT 5823), adenyl cyclase (SQ 22536) and protein kinase A (KT 5720), but not by inhibition of NO-synthesis (L-NAME). In addition, milrinone-induced relaxation was dependent on the activation of KATP-, BKCa 2+- and Kv-channels. Human PVs also relaxed to milrinone (121%), however only if pre-constricted. Discussion Milrinone relaxes PVs from GPs and humans. In GPs, milrinone-induced relaxation is based on KATP-, BKCa 2+- and Kv-channel-activation and on cAMP/PKA/PKG. The relaxant properties of milrinone on PVs lead to reduced postcapillary resistance and hydrostatic pressures. Hence they alleviate pulmonary edema and suggest beneficial effects of milrinone in PH due to left heart disease. PMID:24498166

Milrinone relaxes pulmonary veins in guinea pigs and humans.

PubMed

Rieg, Annette D; Suleiman, Said; Perez-Bouza, Alberto; Braunschweig, Till; Spillner, Jan W; Schröder, Thomas; Verjans, Eva; Schälte, Gereon; Rossaint, Rolf; Uhlig, Stefan; Martin, Christian

2014-01-01

The phosphodiesterase-III inhibitor milrinone improves ventricular contractility, relaxes pulmonary arteries and reduces right ventricular afterload. Thus, it is used to treat heart failure and pulmonary hypertension (PH). However, its action on pulmonary veins (PVs) is not defined, although particularly PH due to left heart disease primarily affects the pulmonary venous bed. We examined milrinone-induced relaxation in PVs from guinea pigs (GPs) and humans. Precision-cut lung slices (PCLS) were prepared from GPs or from patients undergoing lobectomy. Milrinone-induced relaxation was studied by videomicroscopy in naïve PVs and in PVs pre-constricted with the ETA-receptor agonist BP0104. Baseline luminal area was defined as 100%. Intracellular cAMP was measured by ELISA and milrinone-induced changes of segmental vascular resistances were studied in the GP isolated perfused lung (IPL). In the IPL (GP), milrinone (10 µM) lowered the postcapillary resistance of pre-constricted vessels. In PCLS (GP), milrinone relaxed naïve and pre-constricted PVs (120%) and this relaxation was attenuated by inhibition of protein kinase G (KT 5823), adenyl cyclase (SQ 22536) and protein kinase A (KT 5720), but not by inhibition of NO-synthesis (L-NAME). In addition, milrinone-induced relaxation was dependent on the activation of K ATP-, BK Ca (2+)- and Kv-channels. Human PVs also relaxed to milrinone (121%), however only if pre-constricted. Milrinone relaxes PVs from GPs and humans. In GPs, milrinone-induced relaxation is based on K ATP-, BK Ca (2+)- and Kv-channel-activation and on cAMP/PKA/PKG. The relaxant properties of milrinone on PVs lead to reduced postcapillary resistance and hydrostatic pressures. Hence they alleviate pulmonary edema and suggest beneficial effects of milrinone in PH due to left heart disease.

IRAP inhibition using HFI419 prevents moderate to severe acetylcholine mediated vasoconstriction in a rabbit model.

PubMed

El-Hawli, Aisha; Qaradakhi, Tawar; Hayes, Alan; Rybalka, Emma; Smith, Renee; Caprnda, Martin; Opatrilova, Radka; Gazdikova, Katarina; Benckova, Maria; Kruzliak, Peter; Zulli, Anthony

2017-02-01

Coronary artery vasospasm (constriction) caused by reduced nitric oxide bioavailability leads to myocardial infarction. Reduced endothelial release of nitric oxide by the neurotransmitter acetylcholine, leads to paradoxical vasoconstriction as it binds to smooth muscle cell M3 receptors. Thus, inhibition of coronary artery vasospasm will improve clinical outcomes. Inhibition of insulin regulated aminopeptidase has been shown to improve vessel function, thus we tested the hypothesis that HFI419, an inhibitor of insulin regulated aminopeptidase, could reduce blood vessel constriction to acetylcholine. The abdominal aorta was excised from New Zealand white rabbits (n=15) and incubated with 3mM Hcy to induce vascular dysfunction in vitro for 1h. HFI419 was added 5min prior to assessment of vascular function by cumulative doses of acetylcholine. In some rings, vasoconstriction to acetylcholine was observed in aortic rings after pre-incubation with 3mM homocysteine. Incubation with HFI419 inhibited the vasoconstrictive response to acetylcholine, thus improving, but not normalizing, vascular function (11.5±8.9% relaxation vs 79.2±37% constriction, p<0.05). Similarly, in another group with mild vasoconstriction, HFI419 inhibited this effect (34.9±4.6% relaxation vs 11.1±5.2%, constriction, p<0.05). HFI419 had no effect on control aorta or aorta with mild aortic dysfunction. The present study shows that HFI419 prevents acetylcholine mediated vasoconstriction in dysfunctional blood vessels. HFI419 had no effect on normal vasodilation. Our results indicate a therapeutic potential of HFI419 in reducing coronary artery vasospasm. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

The progestin levonorgestrel induces endothelium-independent relaxation of rabbit jugular vein via inhibition of calcium entry and protein kinase C: role of cyclic AMP

PubMed Central

Herkert, Olaf; Kuhl, Herbert; Busse, Rudi; Schini-Kerth, Valérie B

2000-01-01

The progestin and oestrogen component of oral contraceptives have been involved in the development of venous thromboembolic events in women. In the present study we determined the vasoactive effects of sex steroids used in oral contraceptives in isolated preconstricted rabbit jugular veins in the presence of diclofenac and examined the underlying mechanisms.The natural hormone progesterone, the synthetic progestins levonorgestrel, 3-keto-desogestrel, gestodene and chlormadinone acetate, and the synthetic estrogen 17 α-ethinyloestradiol induced concentration-dependent relaxations of endothelium-intact veins constricted with U46619. Levonorgestrel also inhibited constrictions evoked by either a high potassium (K+) solution or phorbol myristate acetate (PMA) in the absence and presence of extracellular calcium (Ca2+). In addition, levonorgestrel depressed contractions evoked by Ca2+ and reduced 45Ca2+ influx in depolarized veins.Relaxations to levonorgestrel in U46619-constricted veins were neither affected by the presence of the endothelium nor by the inhibitor of soluble guanylyl cyclase, NS2028, but were significantly improved either by the selective cyclic AMP phosphodiesterase inhibitor rolipram or in the absence of diclofenac, and decreased by the protein kinase A inhibitor, Rp-8-CPT-cAMPS. Rolipram also potentiated relaxations to levonorgestrel in PMA-constricted veins in the presence, but not in the absence of extracellular Ca2+. Levonorgestrel increased levels of cyclic AMP and inhibited PMA-induced activation of protein kinase C in veins.These findings indicate that levonorgestrel caused endothelium-independent relaxations of jugular veins via inhibition of Ca2+ entry and of protein kinase C activation. In addition, the cyclic AMP effector pathway contributes to the levonorgestrel-induced relaxation possibly by depressing Ca2+ entry. PMID:10952682

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 American Heart Association, Inc.

Inhibitory effect of rhynchophylline on contraction of cerebral arterioles to endothelin 1: role of rho kinase.

PubMed

Hao, Hui-Feng; Liu, Li-Mei; Liu, Yu-Ying; Liu, Juan; Yan, Li; Pan, Chun-Shui; Wang, Ming-Xia; Wang, Chuan-She; Fan, Jing-Yu; Gao, Yuan-Sheng; Han, Jing-Yan

2014-08-08

Rhynchophylline (Rhy) is a major ingredient of Uncaria rhynchophylla (UR) used to reduce blood pressure and ameliorate brain ailments. This study was to examine the role of Rho kinase (ROCK) in the inhibition of Rhy on contraction of cerebral arterioles caused by endothelin 1 (ET-1). Cerebral arterioles of male Wistar rats were constricted with ET-1 for 10 min followed by perfusion of Rhy for 20 min. Changes in the diameters of the arterioles were recorded. The effects of Rhy on contraction of middle cerebral arteries (MCAs) were determined by a Multi-Myograph. Western blotting and immunofluorescent staining were used to examine the effects of Rhy on RhoA translocation and myosin phosphatase target subunit 1 (MYPT1) phosphorylation. In vivo, Rhy (30-300 µM) relaxed cerebral arterioles constricted with ET-1 dose-dependently. In vitro, Rhy at lower concentrations (1-100 µM) caused relaxation of rat MCAs constricted with KCl and Bay-K8644 (an agonist of L-type voltage-dependent calcium channels (L-VDCCs)). Rhy at higher concentrations (>100 µM) caused relaxation of rat MCAs constricted with ET-1, which was inhibited by Y27632, a ROCK׳s inhibitor. Western blotting of rat aortas showed that Rhy inhibited RhoA translocation and MYPT1 phosphorylation. Immunofluorescent staining of MCAs confirmed that phosphorylation of MYPT1 caused by ET-1 was inhibited by Rhy. These results demonstrate that Rhy is a potent inhibitor of contraction of cerebral arteries caused by ET-1 in vivo and in vitro. The effect of Rhy was in part mediated by inhibiting RhoA-ROCK signaling. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Red Blood Cell Deformation Under Shear Flow: The Effect of Changing Cell Properties

NASA Astrophysics Data System (ADS)

Forsyth, Alison M.; Wan, Jiandi; Ristenpart, William D.; Stone, Howard A.

2008-11-01

The deformability of red blood cells plays a major role in the pathology of several diseases, including malaria, sickle cell anemia and spherocytosis. Moreover, deformations are believed to trigger the release of adenosine triphosphate, which helps regulate vascular tone and is consequently an important factor in various vascular diseases. Here we investigate single-cell viscoelastic responses to increased shear stress in poly(dimethylsiloxane) channels with a single constriction 2-4 times larger than a typical erythrocyte. These channels mimic arteriole-sized vessels, and have the advantage that the cell membrane is not in contact with the channel walls which have vastly different mechanical and material properties than living tissue. High-speed video and image analysis were used to quantify the trajectories and deformations of cells exposed to varied doses of diamide, a chemical known to ``rigidify'' erythrocytes. Our results show that (i) deformation is proportional to shear rate and (ii) the deformability of diamide-treated cells is greater than that of untreated cells. The latter is an unforeseen result because micropipette aspiration experiments have shown the opposite. We expect that the experimental procedure described here will be useful for characterizing the effect of different therapeutic agents on cellular deformability.

Overexpression of SerpinE2/protease nexin-1 Contribute to Pathological Cardiac Fibrosis via increasing Collagen Deposition

PubMed Central

Li, Xuelian; Zhao, Dandan; Guo, Zhenfeng; Li, Tianshi; Qili, Muge; Xu, Bozhi; Qian, Ming; Liang, Haihai; E, Xiaoqiang; Chege Gitau, Samuel; Wang, Lu; Huangfu, Longtao; Wu, Qiuxia; Xu, Chaoqian; Shan, Hongli

2016-01-01

Although increases in cardiovascular load (pressure overload) are known to elicit ventricular remodeling including cardiomyocyte hypertrophy and interstitial fibrosis, the molecular mechanisms of pressure overload or AngII -induced cardiac interstitial fibrosis remain elusive. In this study, serpinE2/protease nexin-1 was over-expressed in a cardiac fibrosis model induced by pressure-overloaded via transverse aortic constriction (TAC) in mouse. Knockdown of serpinE2 attenuates cardiac fibrosis in a mouse model of TAC. At meantime, the results showed that serpinE2 significantly were increased with collagen accumulations induced by AngII or TGF-β stimulation in vitro. Intriguingly, extracellular collagen in myocardial fibroblast was reduced by knockdown of serpinE2 compared with the control in vitro. In stark contrast, the addition of exogenous PN-1 up-regulated the content of collagen in myocardial fibroblast. The MEK1/2- ERK1/2 signaling probably promoted the expression of serpinE2 via transcription factors Elk1 in myocardial fibroblast. In conclusion, stress-induced the ERK1/2 signaling pathway activation up-regulated serpinE2 expression, consequently led accumulation of collagen protein, and contributed to cardiac fibrosis. PMID:27876880

Developmental heterogeneity of cardiac fibroblasts does not predict pathological proliferation and activation.

PubMed

Ali, Shah R; Ranjbarvaziri, Sara; Talkhabi, Mahmood; Zhao, Peng; Subat, Ali; Hojjat, Armin; Kamran, Paniz; Müller, Antonia M S; Volz, Katharina S; Tang, Zhaoyi; Red-Horse, Kristy; Ardehali, Reza

2014-09-12

Fibrosis is mediated partly by extracellular matrix-depositing fibroblasts in the heart. Although these mesenchymal cells are reported to have multiple embryonic origins, the functional consequence of this heterogeneity is unknown. We sought to validate a panel of surface markers to prospectively identify cardiac fibroblasts. We elucidated the developmental origins of cardiac fibroblasts and characterized their corresponding phenotypes. We also determined proliferation rates of each developmental subset of fibroblasts after pressure overload injury. We showed that Thy1(+)CD45(-)CD31(-)CD11b(-)Ter119(-) cells constitute the majority of cardiac fibroblasts. We characterized these cells using flow cytometry, epifluorescence and confocal microscopy, and transcriptional profiling (using reverse transcription polymerase chain reaction and RNA-seq). We used lineage tracing, transplantation studies, and parabiosis to show that most adult cardiac fibroblasts derive from the epicardium, a minority arises from endothelial cells, and a small fraction from Pax3-expressing cells. We did not detect generation of cardiac fibroblasts by bone marrow or circulating cells. Interestingly, proliferation rates of fibroblast subsets on injury were identical, and the relative abundance of each lineage remained the same after injury. The anatomic distribution of fibroblast lineages also remained unchanged after pressure overload. Furthermore, RNA-seq analysis demonstrated that Tie2-derived and Tbx18-derived fibroblasts within each operation group exhibit similar gene expression profiles. The cellular expansion of cardiac fibroblasts after transaortic constriction surgery was not restricted to any single developmental subset. The parallel proliferation and activation of a heterogeneous population of fibroblasts on pressure overload could suggest that common signaling mechanisms stimulate their pathological response. © 2014 American Heart Association, Inc.

Hypertension induces brain β-amyloid accumulation, cognitive impairment, and memory deterioration through activation of receptor for advanced glycation end products in brain vasculature.

PubMed

Carnevale, Daniela; Mascio, Giada; D'Andrea, Ivana; Fardella, Valentina; Bell, Robert D; Branchi, Igor; Pallante, Fabio; Zlokovic, Berislav; Yan, Shirley Shidu; Lembo, Giuseppe

2012-07-01

Although epidemiological data associate hypertension with a strong predisposition to develop Alzheimer disease, no mechanistic explanation exists so far. We developed a model of hypertension, obtained by transverse aortic constriction, leading to alterations typical of Alzheimer disease, such as amyloid plaques, neuroinflammation, blood-brain barrier dysfunction, and cognitive impairment, shown here for the first time. The aim of this work was to investigate the mechanisms involved in Alzheimer disease of hypertensive mice. We focused on receptor for advanced glycation end products (RAGE) that critically regulates Aβ transport at the blood-brain barrier and could be influenced by vascular factors. The hypertensive challenge had an early and sustained effect on RAGE upregulation in brain vessels of the cortex and hippocampus. Interestingly, RAGE inhibition protected from hypertension-induced Alzheimer pathology, as showed by rescue from cognitive impairment and parenchymal Aβ deposition. The increased RAGE expression in transverse aortic coarctation mice was induced by increased circulating advanced glycation end products and sustained by their later deposition in brain vessels. Interestingly, a daily treatment with an advanced glycation end product inhibitor or antioxidant prevented the development of Alzheimer traits. So far, Alzheimer pathology in experimental animal models has been recognized using only transgenic mice overexpressing amyloid precursor. This is the first study demonstrating that a chronic vascular insult can activate brain vascular RAGE, favoring parenchymal Aβ deposition and the onset of cognitive deterioration. Overall we demonstrate that RAGE activation in brain vessels is a crucial pathogenetic event in hypertension-induced Alzheimer disease, suggesting that inhibiting this target can limit the onset of vascular-related Alzheimer disease.

Chronic activation of the low affinity site of β1-adrenoceptors stimulates haemodynamics but exacerbates pressure-overload cardiac remodelling

PubMed Central

Kiriazis, Helen; Tugiono, Niquita; Xu, Qi; Gao, Xiao-Ming; Jennings, Nicole L; Ming, Ziqui; Su, Yidan; Klenowski, Paul; Summers, Roger J; Kaumann, Alberto; Molenaar, Peter; Du, Xiao-Jun

2013-01-01

BACKGROUND AND PURPOSE The β1-adrenoceptor has at least two binding sites, high and low affinity sites (β1H and β1L, respectively), which mediate cardiostimulation. While β1H-adrenoceptor can be blocked by all clinically used β-blockers, β1L-adrenoceptor is relatively resistant to blockade. Thus, chronic β1L-adrenoceptor activation may mediate persistent cardiostimulation, despite the concurrent blockade of β1H-adrenoceptors. Hence, it is important to determine the potential significance of β1L-adrenoceptors in vivo, particularly in pathological situations. EXPERIMENTAL APPROACH C57Bl/6 male mice were used. Chronic (4 or 8 weeks) β1L-adrenoceptor activation was achieved by treatment, via osmotic mini pumps, with (-)-CGP12177 (10 mg·kg−1·day−1). Cardiac function was assessed by echocardiography and micromanometry. KEY RESULTS (-)-CGP12177 treatment of healthy mice increased heart rate and left ventricular (LV) contractility. (-)-CGP12177 treatment of mice subjected to transverse aorta constriction (TAC), during weeks 4–8 or 4–12 after TAC, led to a positive inotropic effect and exacerbated fibrogenic signalling while cardiac hypertrophy tended to be more severe. (-)-CGP12177 treatment of mice with TAC also exacerbated the myocardial expression of hypertrophic, fibrogenic and inflammatory genes compared to untreated TAC mice. Washout of (-)-CGP12177 revealed a more pronounced cardiac dysfunction after 12 weeks of TAC. CONCLUSIONS AND IMPLICATIONS β1L-adrenoceptor activation provides functional support to the heart, in both normal and pathological (pressure overload) situations. Sustained β1L-adrenoceptor activation in the diseased heart exacerbates LV remodelling and therefore may promote disease progression from compensatory hypertrophy to heart failure. PMID:23750586

G Protein-Coupled Receptor-G-Protein βγ-Subunit Signaling Mediates Renal Dysfunction and Fibrosis in Heart Failure.

PubMed

Kamal, Fadia A; Travers, Joshua G; Schafer, Allison E; Ma, Qing; Devarajan, Prasad; Blaxall, Burns C

2017-01-01

Development of CKD secondary to chronic heart failure (CHF), known as cardiorenal syndrome type 2 (CRS2), clinically associates with organ failure and reduced survival. Heart and kidney damage in CRS2 results predominantly from chronic stimulation of G protein-coupled receptors (GPCRs), including adrenergic and endothelin (ET) receptors, after elevated neurohormonal signaling of the sympathetic nervous system and the downstream ET system, respectively. Although we and others have shown that chronic GPCR stimulation and the consequent upregulated interaction between the G-protein βγ-subunit (Gβγ), GPCR-kinase 2, and β-arrestin are central to various cardiovascular diseases, the role of such alterations in kidney diseases remains largely unknown. We investigated the possible salutary effect of renal GPCR-Gβγ inhibition in CKD developed in a clinically relevant murine model of nonischemic hypertrophic CHF, transverse aortic constriction (TAC). By 12 weeks after TAC, mice developed CKD secondary to CHF associated with elevated renal GPCR-Gβγ signaling and ET system expression. Notably, systemic pharmacologic Gβγ inhibition by gallein, which we previously showed alleviates CHF in this model, attenuated these pathologic renal changes. To investigate a direct effect of gallein on the kidney, we used a bilateral ischemia-reperfusion AKI mouse model, in which gallein attenuated renal dysfunction, tissue damage, fibrosis, inflammation, and ET system activation. Furthermore, in vitro studies showed a key role for ET receptor-Gβγ signaling in pathologic fibroblast activation. Overall, our data support a direct role for GPCR-Gβγ in AKI and suggest GPCR-Gβγ inhibition as a novel therapeutic approach for treating CRS2 and AKI. Copyright © 2016 by the American Society of Nephrology.

Pharmacological kynurenine 3-monooxygenase enzyme inhibition significantly reduces neuropathic pain in a rat model.

PubMed

Rojewska, Ewelina; Piotrowska, Anna; Makuch, Wioletta; Przewlocka, Barbara; Mika, Joanna

2016-03-01

Recent studies have highlighted the involvement of the kynurenine pathway in the pathology of neurodegenerative diseases, but the role of this system in neuropathic pain requires further extensive research. Therefore, the aim of our study was to examine the role of kynurenine 3-monooxygenase (Kmo), an enzyme that is important in this pathway, in a rat model of neuropathy after chronic constriction injury (CCI) to the sciatic nerve. For the first time, we demonstrated that the injury-induced increase in the Kmo mRNA levels in the spinal cord and the dorsal root ganglia (DRG) was reduced by chronic administration of the microglial inhibitor minocycline and that this effect paralleled a decrease in the intensity of neuropathy. Further, minocycline administration alleviated the lipopolysaccharide (LPS)-induced upregulation of Kmo mRNA expression in microglial cell cultures. Moreover, we demonstrated that not only indirect inhibition of Kmo using minocycline but also direct inhibition using Kmo inhibitors (Ro61-6048 and JM6) decreased neuropathic pain intensity on the third and the seventh days after CCI. Chronic Ro61-6048 administration diminished the protein levels of IBA-1, IL-6, IL-1beta and NOS2 in the spinal cord and/or the DRG. Both Kmo inhibitors potentiated the analgesic properties of morphine. In summary, our data suggest that in neuropathic pain model, inhibiting Kmo function significantly reduces pain symptoms and enhances the effectiveness of morphine. The results of our studies show that the kynurenine pathway is an important mediator of neuropathic pain pathology and indicate that Kmo represents a novel pharmacological target for the treatment of neuropathy. Copyright © 2015 Elsevier Ltd. All rights reserved.

Peroxisome proliferator-activated receptor-α expression induces alterations in cardiac myofilaments in a pressure-overload model of hypertrophy

PubMed Central

Karam, Chehade N.; Warren, Chad M.; Henze, Marcus; Banke, Natasha H.; Lewandowski, E. Douglas

2017-01-01

Although alterations in fatty acid (FA) metabolism have been shown to have a negative impact on contractility of the hypertrophied heart, the targets of action remain elusive. In this study we compared the function of skinned fiber bundles from transgenic (Tg) mice that overexpress a relatively low level of the peroxisome proliferator-activated receptor α (PPARα), and nontransgenic (NTg) littermates. The mice (NTg-T and Tg-T) were stressed by transverse aortic constriction (TAC) and compared with shams (NTg-S and Tg-S). There was an approximate 4-fold increase in PPARα expression in Tg-S compared with NTg-S, but Tg-T hearts showed the same PPARα expression as NTg-T. Expression of PPARα did not alter the hypertrophic response to TAC but did reduce ejection fraction (EF) in Tg-T hearts compared with other groups. The rate of actomyosin ATP hydrolysis was significantly higher in Tg-S skinned fiber bundles compared with all other groups. Tg-T hearts showed an increase in phosphorylation of specific sites on cardiac myosin binding protein-C (cMyBP-C) and β-myosin heavy chain isoform. These results advance our understanding of potential signaling to the myofilaments induced by altered FA metabolism under normal and pathological states. We demonstrate that chronic and transient PPARα activation during pathological stress alters myofilament response to Ca2+ through a mechanism that is possibly mediated by MyBP-C phosphorylation and myosin heavy chain isoforms. NEW & NOTEWORTHY Data presented here demonstrate novel signaling to sarcomeric proteins by chronic alterations in fatty acid metabolism induced by PPARα. The mechanism involves modifications of key myofilament regulatory proteins modifying cross-bridge dynamics with differential effects in controls and hearts stressed by pressure overload. PMID:28130336

The impact of pressure overload on coronary vascular changes following myocardial infarction in rats.

PubMed

Chen, Jiqiu; Petrov, Artiom; Yaniz-Galende, Elisa; Liang, Lifan; de Haas, Hans J; Narula, Jagat; Hajjar, Roger J

2013-03-01

This study investigates the impact of pressure overload on vascular changes after myocardial infarction (MI) in rats. To evaluate the effect of pressure overload, MI was induced in three groups: 1) left coronary artery ligation for 1 mo (MI-1m), 2) ischemia 30 min/reperfusion for 1 mo (I/R-1m), and 3) ischemia-reperfusion (I/R) was performed after pressure overload induced by aortic banding for 2 mo; 1 mo post-I/R, aortic constriction was released (Ab+I/R+DeAb). Heart function was assessed by echocardiography and in vivo hemodynamics. Resin casting and three-dimensional imaging with microcomputed tomography were used to characterize changes in coronary vasculature. TTC (triphenyltetrazohum chloride) staining and Masson's Trichrome were conducted in parallel experiments. In normal rats, MI induced by I/R and permanent occlusion was transmural or subendocardial. Occluded arterial branches vanished in MI-1m rats. A short residual tail was retained, distal to the occluded site in the ischemic area in I/R-1m hearts. Vascular pathological changes in transmural MI mostly occurred in ischemic areas and remote vasculature remained normal. In pressure overloaded rats, I/R injury induced a sub-MI in which ischemia was transmural, but myocardium in the involved area had survived. The ischemic arterial branches were preserved even though the capillaries were significantly diminished and the pathological changes were extended to remote areas, characterized by fibrosis, atrial thrombus, and pulmonary edema in the Ab+I/R+DeAb group. Pressure overload could increase vascular tolerance to I/R injury, but also trigger severe global ventricular fibrosis and results in atrial thrombus and pulmonary edema.

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

Motion-sensitized SPRITE measurements of hydrodynamic cavitation in fast pipe flow.

PubMed

Adair, Alexander; Mastikhin, Igor V; Newling, Benedict

2018-06-01

The pressure variations experienced by a liquid flowing through a pipe constriction can, in some cases, result in the formation of a bubble cloud (i.e., hydrodynamic cavitation). Due to the nature of the bubble cloud, it is ideally measured through the use of non-optical and non-invasive techniques; therefore, it is well-suited for study by magnetic resonance imaging. This paper demonstrates the use of Conical SPRITE (a 3D, centric-scan, pure phase-encoding pulse sequence) to acquire time-averaged void fraction and velocity information about hydrodynamic cavitation for water flowing through a pipe constriction. Copyright © 2018 Elsevier Inc. All rights reserved.

Self-aligned periodic Ni nano dots embedded in nano-oxide layer

NASA Astrophysics Data System (ADS)

Doi, M.; Izumi, M.; Kawasaki, S.; Miyake, K.; Sahashi, M.

The Ni nano constriction dots embedded in the Ta-nano-oxide layer (NOL) was prepared by the ion beam sputtering (IBS) method. After the various conditions of the oxidations, the structural analyses of the NOL were performed by RHEED, AES and in situ STM/AFM observations. From the current image of the conductive AFM for NOL, the periodically aligned metallic dots with the size around 5-10 nm were successfully observed. The mechanism of the formation of the self-organized aligned Ni nano constriction dots is discussed from the standpoint of the grain size, the crystal orientation, the preferred oxidation of Ta at the diffused interface.

Portable wastewater flow meter

DOEpatents

Hunter, Robert M.

1999-02-02

A portable wastewater flow meter particularly adapted for temporary use at a single location in measuring the rate of liquid flow in a circular entrance conduit of a sewer manhole both under free flow and submerged, open channel conditions and under fill pipe, surcharged conditions, comprising an apparatus having a cylindrical external surface and an inner surface that constricts the flow through the apparatus in such a manner that a relationship exists between (1) the difference between the static pressure head of liquid flowing through the entrance of the apparatus and the static pressure head of liquid flowing through the constriction, and (2) the rate of liquid flow through the apparatus.

Portable wastewater flow meter

DOEpatents

Hunter, Robert M.

1990-01-01

A portable wastewater flow meter particularly adapted for temporary use at a single location in measuring the rate of liquid flow in a circular entrance conduit of a sewer manhole both under free flow and submerged, open channel conditions and under full pipe, surcharged conditions, comprising an apparatus having a cylindrical external surface and an inner surface that constricts the flow through the apparatus in such a manner that a relationship exists between (1) the difference between the static pressure head of liquid flowing through the entrance of the apparatus and the static pressure head of liquid flowing through the constriction, and (2) the rate of liquid flow through the apparatus.

Quasiparticle tunneling in the lowest Landau level

NASA Astrophysics Data System (ADS)

Hennel, Szymon; Scheidegger, Patrick; Kellermeier, Max; Hofmann, Andrea; Krähenmann, Tobias; Reichl, Christian; Wegscheider, Werner; Ihn, Thomas; Ensslin, Klaus

2018-06-01

We measure quasiparticle tunneling across a constriction in the first Landau level. In the limit of weak backscattering, the dependence of the tunneling conductance on temperature and dc-bias is in qualitative disagreement with existing theories. For stronger backscattering, data obtained in the ν =1 /3 state can be fitted to weak backscattering theory with the predicted effective fractional charge of e*=e /3 . The scaling parameter g is however not universal and depends strongly on the gate voltage applied to the constriction. At ν =4 /3 , a more complex picture emerges. We propose an interpretation in terms of selective tunneling between the multiple modes present at the edge.

Quasiparticle relaxation in superconducting nanostructures

NASA Astrophysics Data System (ADS)

Savich, Yahor; Glazman, Leonid; Kamenev, Alex

2017-09-01

We examine energy relaxation of nonequilibrium quasiparticles in "dirty" superconductors with the electron mean free path much shorter than the superconducting coherence length. Relaxation of low-energy nonequilibrium quasiparticles is dominated by phonon emission. We derive the corresponding collision integral and find the quasiparticle relaxation rate. The latter is sensitive to the breaking of time reversal symmetry (TRS) by a magnetic field (or magnetic impurities). As a concrete application of the developed theory, we address quasiparticle trapping by a vortex and a current-biased constriction. We show that trapping of hot quasiparticles may predominantly occur at distances from the vortex core, or the constriction, significantly exceeding the superconducting coherence length.

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.

Two new free-living marine nematode species of the genus Anoplostoma (Anoplostomatidae) from the mangrove habitats of Xiamen Bay, East China Sea

NASA Astrophysics Data System (ADS)

Li, Yongxiang; Guo, Yuqing

2016-02-01

Two new species of free-living marine nematode from mangrove habitats in Xiamen Bay are identified. Anoplostoma tumidum sp. nov. is characterized by relatively short outer labial setae (0.86-1.00 h. d.), long tail (c 7.2-8.9, c' 8.3-10.5), an instinct swollen distal portion of slender spicule (Sc 94-101 µm), and well developed copulatory bursae without bursal papillae. A. tumidum sp. nov. differs from all valid species of genus Anoplostoma in copulatory apparatus of males with a distinct swollen distal portion of spicule, and a relatively obvious constriction of head. A. paraviviparum sp. nov. is characterized by relatively long outer labial setae (1.11-1.22 h. d.), and tail (c 6.6-8.5, c' 8.6-10.2); elongated spicules with distinct knob-like proximal and pointed distal ends (Sc 46-69 µm); distinct strip-like gubernaculum (length with 11-15µm); well developed copulatory bursae with precloacal papillae and post-cloacal papillae; and a distinct constriction of head. A. paraviviparum sp. nov. is similar to A. viviparum Bastian, 1865, but differs in the reproductive mode of female and the constriction of head.

Motion of deformable drops through granular media and other confined geometries.

PubMed

Davis, Robert H; Zinchenko, Alexander Z

2009-06-15

This article features recent simulation studies of the flow of emulsions containing deformable drops through pores, constrictions, and granular media. The flow is assumed to be at low Reynolds number, so that viscous forces dominate, and boundary-integral methods are used to determine interfacial velocities and, hence, track the drop motion and shapes. A single drop in a flat channel migrates to the channel centerplane due to deformation-induced drift, which increases its steady-state velocity along the channel. A drop moving towards a smaller interparticle constriction squeezes through the constriction if the capillary number (ratio of viscous deforming forces and interfacial tension forces) is large enough, but it becomes trapped when the capillary number is below a critical value. These concepts then influence the flow of an emulsion through a granular medium, for which the drop phase moves faster than the suspending liquid at large capillary numbers but slower than the suspending liquid at smaller capillary numbers. The permeabilities of the granular medium to both phases increase with increasing capillary number, due to the reduced resistance to squeezing of easily deformed drops, though drop breakup must also be considered at large capillary numbers.

Surgical management of polyotia.

PubMed

Pan, Bo; Qie, Shuyan; Zhao, Yanyong; Tang, Xiaojun; Lin, Lin; Yang, Qinghua; Zhuang, Hongxing; Jiang, Haiyue

2010-08-01

Polyotia is an extremely rare type of congenital external ear malformation, which is defined as an accessory ear that is large enough to resemble an additional pinna. The terms 'mirror ear' or 'accessory ear' are sometime used. We present our methods in correcting this malformation and summarise the aetiology. The posterior part of the polyotia may presents with a normal ear, a constricted ear or a microtic ear. Free auricular composite tissue transplantation was used to correct the constricted ear. Ear reconstruction was applied in cases of microtia. The anterior auricle was mainly used to form the tragus. 7 cases polyotia were treated between 2004 and 2008. After free auricular composite tissue transplantation the size of the constricted ear and the contralateral ear was similar. In microtia cases the reconstructed ears were natural looking and had a satisfactory three-dimensional contour. The extra tissue of the anterior ear was excised and the tragus was reconstructed. Through operative intervention tailored to the individual case natural-looking and symmetric ears were acquired. The aetiology of polyotia probably relates to abnormal migration of neural crest cell. Copyright 2009 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Quantitative Measures of Swallowing Deficits in Patients With Parkinson's Disease.

PubMed

Ellerston, Julia K; Heller, Amanda C; Houtz, Daniel R; Kendall, Katherine A

2016-05-01

Dysphagia and associated aspiration pneumonia are commonly reported sequelae of Parkinson's disease (PD). Previous studies of swallowing in patients with PD have described prolonged pharyngeal transit time, delayed onset of pharyngeal transit, cricopharyngeal (CP) achalasia, reduced pharyngeal constriction, and slowed hyolaryngeal elevation. These studies were completed using inconsistent evaluation methodology, reliance on qualitative analysis, and a lack of a large control group, resulting in concerns regarding diagnostic precision. The purpose of this study was to investigate swallowing function in patients with PD using a norm-referenced, quantitative approach. This retrospective study includes 34 patients with a diagnosis of PD referred to a multidisciplinary voice and swallowing clinic. Modified barium swallow studies were performed using quantitative measures of pharyngeal transit time, hyoid displacement, CP sphincter opening, area of the pharynx at maximal constriction, and timing of laryngeal vestibule closure relative to bolus arrival at the CP sphincter. Reduced pharyngeal constriction was found in 30.4%, and a delay in airway closure relative to arrival of the bolus at the CP sphincter was the most common abnormality, present in 62% of patients. Previously reported findings of prolonged pharyngeal transit, poor hyoid elevation, and CP achalasia were not identified as prominent features. © The Author(s) 2015.

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.

Role of Copper and Homocysteine in Pressure Overload Heart Failure

PubMed Central

Hughes, William M.; Rodriguez, Walter E.; Rosenberger, Dorothea; Chen, Jing; Sen, Utpal; Tyagi, Neetu; Moshal, Karni S.; Vacek, Thomas; Kang, Y. James

2009-01-01

Elevated levels of homocysteine (Hcy) (known as hyperhomocysteinemia HHcy) are involved in dilated cardiomyopathy. Hcy chelates copper and impairs copper-dependent enzymes. Copper deficiency has been linked to cardiovascular disease. We tested the hypothesis that copper supplement regresses left ventricular hypertrophy (LVH), fibrosis and endothelial dysfunction in pressure overload DCM mice hearts. The mice were grouped as sham, sham + Cu, aortic constriction (AC), and AC + Cu. Aortic constriction was performed by transverse aortic constriction. The mice were treated with or without 20 mg/kg copper supplement in the diet for 12 weeks. The cardiac function was assessed by echocardiography and electrocardiography. The matrix remodeling was assessed by measuring matrix metalloproteinase (MMP), tissue inhibitor of metalloproteinases (TIMPs), and lysyl oxidase (LOX) by Western blot analyses. The results suggest that in AC mice, cardiac function was improved with copper supplement. TIMP-1 levels decreased in AC and were normalized in AC + Cu. Although MMP-9, TIMP-3, and LOX activity increased in AC and returned to baseline value in AC + Cu, copper supplement showed no significant effect on TIMP-4 activity after pressure overload. In conclusion, our data suggest that copper supplement helps improve cardiac function in a pressure overload dilated cardiomyopathic heart. PMID:18679830

Red Blood Cell Passage of Small Capillaries Is Associated with Transient Ca2+-mediated Adaptations.

PubMed

Danielczok, Jens G; Terriac, Emmanuel; Hertz, Laura; Petkova-Kirova, Polina; Lautenschläger, Franziska; Laschke, Matthias W; Kaestner, Lars

2017-01-01

When red blood cells (RBCs) pass constrictions or small capillaries they need to pass apertures falling well below their own cross section size. We used different means of mechanical stimulations (hypoosmotic swelling, local mechanical stimulation, passing through microfluidic constrictions) to observe cellular responses of human RBCs in terms of intracellular Ca 2+ -signaling by confocal microscopy of Fluo-4 loaded RBCs. We were able to confirm our in vitro results in a mouse dorsal skinfold chamber model showing a transiently increased intracellular Ca 2+ when RBCs were passing through small capillaries in vivo . Furthermore, we performed the above-mentioned in vitro experiments as well as measurements of RBCs filterability under various pharmacological manipulations (GsMTx-4, TRAM-34) to explore the molecular mechanism of the Ca 2+ -signaling. Based on these experiments we conclude that mechanical stimulation of RBCs activates mechano-sensitive channels most likely Piezo1. This channel activity allows Ca 2+ to enter the cell, leading to a transient activation of the Gardos-channel associated with K + , Cl - , and water loss, i.e., with a transient volume adaptation facilitating the passage of the RBCs through the constriction.

Red Blood Cell Passage of Small Capillaries Is Associated with Transient Ca2+-mediated Adaptations

PubMed Central

Danielczok, Jens G.; Terriac, Emmanuel; Hertz, Laura; Petkova-Kirova, Polina; Lautenschläger, Franziska; Laschke, Matthias W.; Kaestner, Lars

2017-01-01

When red blood cells (RBCs) pass constrictions or small capillaries they need to pass apertures falling well below their own cross section size. We used different means of mechanical stimulations (hypoosmotic swelling, local mechanical stimulation, passing through microfluidic constrictions) to observe cellular responses of human RBCs in terms of intracellular Ca2+-signaling by confocal microscopy of Fluo-4 loaded RBCs. We were able to confirm our in vitro results in a mouse dorsal skinfold chamber model showing a transiently increased intracellular Ca2+ when RBCs were passing through small capillaries in vivo. Furthermore, we performed the above-mentioned in vitro experiments as well as measurements of RBCs filterability under various pharmacological manipulations (GsMTx-4, TRAM-34) to explore the molecular mechanism of the Ca2+-signaling. Based on these experiments we conclude that mechanical stimulation of RBCs activates mechano-sensitive channels most likely Piezo1. This channel activity allows Ca2+ to enter the cell, leading to a transient activation of the Gardos-channel associated with K+, Cl−, and water loss, i.e., with a transient volume adaptation facilitating the passage of the RBCs through the constriction. PMID:29259557

Therapeutic ultrasound suppresses neuropathic pain and upregulation of substance P and neurokinin-1 receptor in rats after peripheral nerve injury.

PubMed

Chen, Yu-Wen; Tzeng, Jann-Inn; Huang, Po-Ching; Hung, Ching-Hsia; Shao, Dong-Zi; Wang, Jhi-Joung

2015-01-01

We studied the mechanisms and impact of therapeutic ultrasound (TU) for pain caused by nerve injury. TU began on post-operative day 5 (POD5) and then continued daily for the next 22 d. Sensitivity to thermal and mechanical stimuli and levels of neurokinin-1 receptor, substance P, tumor necrosis factor-α and interleukin-6 in the sciatic nerve were examined. On POD7, chronic constriction injury rats undergoing TU at an intensity of 1 W/cm(2), but not 0.25 or 0.5 W/cm(2), had increases in both the mechanical withdrawal threshold and the thermal withdrawal latency compared with the chronic constriction injury group. Moreover, chronic constriction injury rats exhibited upregulation of neurokinin-1 receptor, substance P, tumor necrosis factor-α and interleukin-6 in the sciatic nerve on PODs 14 and 28, whereas TU inhibited their increased expression. We suggest that the efficacy of TU is dependent on its ability to limit the upregulation of neurokinin-1 receptor, substance P, tumor necrosis factor-α and interleukin-6 around the injured sciatic nerve. Copyright © 2015 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

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

[The contribution of endogenous vasodilators to the control of glomerular hemodynamics].

PubMed

Arima, S; Ito, S; Abe, K

1994-06-01

Preglomerular afferent (Af-) and postglomerular efferent arterioles (Ef-Arts) are crucial vascular segments in the control of glomerular hemodynamics. However, their vascular reactivity is not fully understood. We examined: 1) their responses to angiotensin II (AII) or norepinephrine (NE), and 2) the possible modulatory roles of nitric oxide (NO) and prostaglandins (PGs) in these responses. Rabbit Af- or Ef-Arts were microperfused in vitro. Ef-Arts were perfused in either the orthograde direction from the distal end of Af-Arts through the glomerulus (OP) or the retrograde direction from its distal end to eliminate the influence of the glomerulus (RP). Although AII and NE constricted both arterioles in a dose-dependent manner, sensitivity to AII was higher in Ef-Arts. AII began to cause significant (P < 0.01) constriction from 10(-9) M (11 +/- 3%, n = 11) in Af-Arts, and from 10(-11) M in Ef-Arts (OP; 11 +/- 4%, n = 9. RP; 10 +/- 2%, n = 5). In addition, both AII and NE produced stronger constriction of Ef-Arts in RP than OP; AII at 10(-8) M or NE at 10(-6) M decreased the diameter by 35 +/- 4% or 25 +/- 4% in OP and 74 +/- 4% or 62 +/- 7% in RP. NO synthesis inhibitor nitro-L-arginine (L-NAME; 10(-4) M) increased the sensitivity of Af-Art to AII without affecting the reactivity of Ef-Art; in L-NAME-pretreated Af-Arts, AII began to cause significant constriction from 10(-10) M (14 +/- 4%, n = 9, P < 0.01). Thus, L-NAME-pretreatment significantly decreased the differences in sensitivity to AII between Af- and Ef-Arts without affecting different vascular responses between OP and RP. Indomethacin (5 x 10(-5) M) significantly augmented the AII- or NE-induced Ef-Art constriction only in OP; AII at 10(-8) M or NE at 10(-6) M decreased the diameter by 72 +/- 5% (n = 8) or 48 +/- 3% (n = 7). Thus, indomethacin-pretreatment markedly diminished the differences in responses between OP and RP. These results suggest that 1) NO modulates AII action only in the Af-Art, contributing to the difference in sensitivity to AII between Af- and Ef-Art, and 2) the glomerulus controls vascular reactivity of the downstream Ef-Art by releasing PGs.

Further observations on mesenteric vasoconstriction, survival and the clotting defect after endotoxin administration

PubMed Central

Cohen, M. M.; Greenway, C. V.; Innes, I. R.; Lister, G. E.; Murthy, V. S.; Scott, G. D.

1973-01-01

1. The initial response after endotoxin administration (3 mg/kg) in cats involved pulmonary vasoconstriction. This was not seen when endotoxin was given by slow infusion and it could be prevented after a bolus injection of endotoxin by pretreatment of the cats with aspirin (10 mg/kg). Intense mesenteric vasoconstriction occurred in all the cats. 2. The mesenteric vasoconstriction was a specific response of the mesenteric blood vessels. At the time the mesenteric bed constricted, the renal bed dilated, the hepatic arterial bed remained unchanged and the smooth muscle of the intestinal wall relaxed. 3. Arterial blood from cats with a fully developed mesenteric vasoconstriction after endotoxin administration was perfused through a normal intestine. No immediate vasoconstriction developed but the perfused intestine constricted slowly over 60 minutes. This suggests that mesenteric constriction was not due to circulating vasoconstrictor factors or the intestinal innervation, but involved a slow local mechanism within the intestine. It could not be prevented or reversed by a variety of pharmacological agents. 4. These observations suggest that endotoxin caused a unique type of mesenteric vasoconstriction in cats by a local mechanism which took up to 60 min to develop, was sufficiently potent to reduce mesenteric flow to <30% control, and was maintained until death of the cats. Blood from these animals did not clot when placed in a glass tube. 5. The mesenteric constriction and the clotting defect could be prevented by repeated administration of aminophylline and dextran solution before and after a bolus intravenous injection of endotoxin. Arterial pressure and mesenteric flow were maintained for at least 10 h in these experiments. Inadequate treatment intensified rather than reduced the intestinal mucosal damage. 6. Cats were treated with aspirin, endotoxin and the optimal regimen for prevention of the mesenteric constriction and allowed to recover from the anaesthetic agent. In this series, 63% survived indefinitely compared to 25% after aspirin and endotoxin treatment and 0% after endotoxin alone. 7. The possible mechanisms of action of aspirin and aminophylline-dextran solution are discussed. Our failure to obtain 100% survival is probably due to pulmonary damage which develops 10-24 h after endotoxin administration. This delayed pulmonary action of endotoxin is not prevented by aspirin treatment and it seems unlikely that aspirin will be of any value in the treatment of the pulmonary lesion in man. PMID:4788202

Experimental Assessment of the Laryngeal Jet Effect on the Fluid Flow Pattern within the Trachea

NASA Astrophysics Data System (ADS)

Salehi, Mehran

Drug aerosol inhalation is a modern way to combat lung diseases. It is also becoming the preferred route for insulin delivery, pain management, cancer therapy and nanotherapetutics. The specific airflow characteristics within the central human airways, however, have a major influence on aerosol delivery and particle deposition. In this study the association of human inspiratory laryngeal function on the unique transitional turbulence this creates in the central airways and its association to particle deposition were investigated. The true vocal cords expand with increasing inspiratory flow rates and independently, with enlarging lung volumes. This creates a specific constriction to the inspiratory airstream and subsequent vortex formation below each vocal cord. The study compares triangular vocal cord shapes (physiologic) to rectangular (symmetric) shapes over a range of inspiratory directed flows. Disturbances below the laryngeal obstruction were visualized and the turbulence intensities as a function of distance below the vocal cord constriction in scale models under similitude flow conditions for a human trachea was also measured using laser Doppler anemometry in both primary (axial) and secondary (tangential) directions in a simplified larynx-trachea model. The turbulence length scale and energy spectrum were also calculated using hot-wire anemometer data to determine the size distribution of eddies and the rate of energy decay along the trachea for different larynx geometries and Reynolds numbers. Both visualizations and measurements were made at Reynolds numbers between 1000 and 4000 which represent mild to severe breathing conditions. The larynx geometry is modeled by a constriction inside a straight tube. The group of constrictions consists of 2 rectangular and triangular shapes at apex angles of 45°, 60° and 75° degrees. The base circular tube was 5 cm in diameter (D) and 30 cm in length (L) (to keep the relative ratio of L/D=6). The inlet area created by the larynx constriction is approximately 10% and 50% of the tube area. Forty eight different combinations of aperture, area ratio, angle of the glottis and flow rates were visualized. Arrays of 72 measurements were made respectively at downstream planes of 1D and 3D from the larynx within the trachea. Results show that both the average and rms velocities change rapidly with respect to distance down the trachea. High levels of turbulence intensity at the anterior part indicate the potential region for particle deposition. The two vortices below the laryngeal constriction appear to interact, creating a transitional turbulence which propagates down the trachea, developing a structure to the turbulence which enhances the lateral flow energies and in turn enhances particle movements toward the tracheal walls (especially the posterior membranous tracheal wall) and subsequent particle capture. It appears that the locations of particle capture on the tracheal walls are at sites optimal for subsequent expectoration with cough.

MicroRNA-1 Downregulation Increases Connexin 43 Displacement and Induces Ventricular Tachyarrhythmias in Rodent Hypertrophic Hearts

PubMed Central

Curcio, Antonio; Torella, Daniele; Iaconetti, Claudio; Pasceri, Eugenia; Sabatino, Jolanda; Sorrentino, Sabato; Giampà, Salvatore; Micieli, Mariella; Polimeni, Alberto; Henning, Beverley J.; Leone, Angelo; Catalucci, Daniele; Ellison, Georgina M.; Condorelli, Gianluigi; Indolfi, Ciro

2013-01-01

Downregulation of the muscle-specific microRNA-1 (miR-1) mediates the induction of pathologic cardiac hypertrophy. Dysfunction of the gap junction protein connexin 43 (Cx43), an established miR-1 target, during cardiac hypertrophy leads to ventricular tachyarrhythmias (VT). However, it is still unknown whether miR-1 and Cx43 are interconnected in the pro-arrhythmic context of hypertrophy. Thus, in this study we investigated whether a reduction in the extent of cardiac hypertrophy could limit the pathological electrical remodeling of Cx43 and the onset of VT by modulating miR-1 levels. Wistar male rats underwent mechanical constriction of the ascending aorta to induce pathologic left ventricular hypertrophy (LVH) and afterwards were randomly assigned to receive 10mg/kg valsartan, VAL (LVH+VAL) delivered in the drinking water or placebo (LVH) for 12 weeks. Sham surgery was performed for control groups. Programmed ventricular stimulation reproducibly induced VT in LVH compared to LVH+VAL group. When compared to sham controls, rats from LVH group showed a significant decrease of miR-1 and an increase of Cx43 expression and its ERK1/2-dependent phosphorylation, which displaces Cx43 from the gap junction. Interestingly, VAL administration to rats with aortic banding significantly reduced cardiac hypertrophy and prevented miR-1 down-regulation and Cx43 up-regulation and phosphorylation. Gain- and loss-of-function experiments in neonatal cardiomyocytes (NCMs) in vitro confirmed that Cx43 is a direct target of miR-1. Accordingly, in vitro angiotensin II stimulation reduced miR-1 levels and increased Cx43 expression and phosphorylation compared to un-stimulated NCMs. Finally, in vivo miR-1 cardiac overexpression by an adenoviral vector intra-myocardial injection reduced Cx43 expression and phosphorylation in mice with isoproterenol-induced LVH. In conclusion, miR-1 regulates Cx43 expression and activity in hypertrophic cardiomyocytes in vitro and in vivo. Treatment of pressure overload-induced myocyte hypertrophy reduces the risk of life-threatening VT by normalizing miR-1 expression levels with the consequent stabilization of Cx43 expression and activity within the gap junction. PMID:23922949

HSF1 and NF-κB p65 participate in the process of exercise preconditioning attenuating pressure overload-induced pathological cardiac hypertrophy

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

Xu, Tongyi; Department of Cardiothoracic Surgery, Changhai Hospital, Second Military Medical University, Shanghai; Zhang, Ben

Pathological cardiac hypertrophy, often accompanied by hypertension, aortic stenosis and valvular defects, is typically associated with myocyte remodeling and cardiac dysfunction. Exercise preconditioning (EP) has been proven to enhance the tolerance of the myocardium to cardiac ischemia-reperfusion injury. However, the effects of EP in pathological cardiac hypertrophy are rarely reported. 10-wk-old male Sprague–Dawley rats (n = 80) were randomly divided into four groups: sham, TAC, EP + sham and EP + TAC. Two EP groups were subjected to 4 weeks of treadmill training, and the EP + TAC and TAC groups were followed by TAC operations. The sham and EP + sham groups underwent the same operation without aortic constriction.more » Eight weeks after the surgery, we evaluated the effects of EP by echocardiography, morphology, and histology and observed the expressions of the associated proteins. Compared with the respective control groups, hypertrophy-related indicators were significantly increased in the TAC and EP + TAC groups (p < 0.05). However, between the TAC and EP + TAC groups, all of these changes were effectively inhibited by EP treatment (p < 0.05). Furthermore, EP treatment upregulated the expression of HSF1 and HSP70, increased the HSF1 levels in the nuclear fraction, inhibited the expression of the NF-κB p65 subunit, decreased the NF-κB p65 subunit levels in the nuclear fraction, and reduced the IL2 levels in the myocardia of rats. EP could effectively reduce the cardiac hypertrophic responses induced by TAC and may play a protective role by upregulating the expressions of HSF1 and HSP70, activating HSF1 and then inhibiting the expression of NF-κB p65 and nuclear translocation. - Highlights: • EP could effectively reduce the cardiac hypertrophic responses induced by TAC. • EP may play a protective role by upregulating the expressions of HSF1 and HSP70 and then activating HSF1. • EP may play a protective role by inhibiting the expression of NF-κB p65 and nuclear translocation.« less

Virtual pathology of cervical radiculopathy based on 3D MR/CT fusion images: impingement, flattening or twisted condition of the compressed nerve root in three cases.

PubMed

Kamogawa, Junji; Kato, Osamu; Morizane, Tatsunori; Hato, Taizo

2015-01-01

There have been several imaging studies of cervical radiculopathy, but no three-dimensional (3D) images have shown the path, position, and pathological changes of the cervical nerve roots and spinal root ganglion relative to the cervical bony structure. The objective of this study was to introduce a technique that enables the virtual pathology of the nerve root to be assessed using 3D magnetic resonance (MR)/computed tomography (CT) fusion images that show the compression of the proximal portion of the cervical nerve root by both the herniated disc and the preforaminal or foraminal bony spur in patients with cervical radiculopathy. MR and CT images were obtained from three patients with cervical radiculopathy. 3D MR images were placed onto 3D CT images using a computer workstation. The entire nerve root could be visualized in 3D with or without the vertebrae. The most important characteristic evident on the images was flattening of the nerve root by a bony spur. The affected root was constricted at a pre-ganglion site. In cases of severe deformity, the flattened portion of the root seemed to change the angle of its path, resulting in twisted condition. The 3D MR/CT fusion imaging technique enhances visualization of pathoanatomy in cervical hidden area that is composed of the root and intervertebral foramen. This technique provides two distinct advantages for diagnosis of cervical radiculopathy. First, the isolation of individual vertebra clarifies the deformities of the whole root groove, including both the uncinate process and superior articular process in the cervical spine. Second, the tortuous or twisted condition of a compressed root can be visualized. The surgeon can identify the narrowest face of the root if they view the MR/CT fusion image from the posterolateral-inferior direction. Surgeons use MR/CT fusion images as a pre-operative map and for intraoperative navigation. The MR/CT fusion images can also be used as educational materials for all hospital staff and for patients and patients' families who provide informed consent for treatments.

Laser-Generated Ultrasonic Source for a Real-Time Dry-Contact Imaging System

NASA Astrophysics Data System (ADS)

Petculescu, G.; Zhou, Y.; Komsky, I.; Krishnaswamy, S.

2006-03-01

A laser-generated ultrasonic source, to be used with a real-time imaging device, was developed. The ultrasound is generated in the thermoelastic regime, in a composite layer composed of absorbing particles (carbon) and silicone rubber. The composite layer plays three roles: of absorption, constriction and dry-coupling. The central frequency of the generated pulse was controlled by varying the absorption depth of the generation layer. The maximum peak frequency obtained was 4MHz. When additional constriction was provided to the composite layer, the amplitude of the generated signal increased further, due to the large thermal expansion coefficient of the silicone. Images using the laser-generated ultrasonic source were taken.

Tuning temperature and size of hot spots and hot-spot arrays.

PubMed

Saïdi, Elika; Babinet, Nicolas; Lalouat, Loïc; Lesueur, Jérôme; Aigouy, Lionel; Volz, Sébastian; Labéguerie-Egéa, Jessica; Mortier, Michel

2011-01-17

By using scanning thermal microscopy, it is shown that nanoscale constrictions in metallic microwires deposited on an oxidized silicon substrate can be tuned in terms of temperature and confinement size. High-resolution temperature maps indeed show that submicrometer hot spots and hot-spot arrays are obtained when the SiO(2) layer thickness decreases below 100 nm. When the SiO(2) thickness becomes larger, heat is less confined in the vicinity of the constrictions and laterally spreads all along the microwire. These results are in good agreement with numerical simulations, which provide dependences between silica-layer thickness and nanodot shape and temperature. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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 interaction of pupil response with the vergence system.

PubMed

Feil, Moritz; Moser, Barbara; Abegg, Mathias

2017-11-01

A gaze shift from a target at distance to a target at near leads to pupillary constriction. The regulation of this pupillary near response is ill known. We investigated the impact of accommodation, convergence, and proximity on the pupillary diameter. We recorded pupil size and vergence eye movements with the use of an infrared eye tracker. We determined the pupillary response in four conditions: (1) after a gaze shift from far to near without accommodation, (2) after a gaze shift from far to near with neither accommodation nor convergence, (3) after accommodation alone, and (4) after accommodation with convergence without a gaze shift to near. These responses were compared to the pupil response of a full near response and to a gaze shift from one far target to another. We found a reliable pupillary near response. The removal of both accommodation and convergence in gaze shift from far to near abolished the pupillary near response. Accommodation alone did not induce pupillary constriction, while convergence and accommodation together induced a pupil response similar to the full near response. The main trigger for the pupillary response seems to be convergence. Neither accommodation nor proximity alone induce a significant pupillary constriction. This suggests that the miosis of the near triad is closely coupled to the vergence system rather than being independently regulated.

Measurement of bridge scour at the SR-32 crossing of the Sacramento River at Hamilton City, California, 1987-92

USGS Publications Warehouse

Blodgett, J.C.; Harris, Carroll D.; ,

1993-01-01

A study of the State Route 32 crossing of the Sacramento River near Hamilton City, California, is being made to determine those channel and bridge factors that contribute to scour at the site. Three types of scour data have been measured-channel bed (natural) scour, constriction (general) scour, and local (bridge-pier induced) scour. During the years 1979-93, a maximum of 3.4 ft of channel bed scour, with a mean of 1.4 ft, has been measured. Constriction scour, which may include channel bed scour, has been measured at the site nine times during the years 1987-92. The calculated amount of constriction scour ranged from 0.2 to 3.0 ft, assuming the reference is the mean bed elevation. Local scour was measured four times at the site in 1991 and 1992 and ranged from -2.1 (fill) to 11.6 ft , with the calculated amounts dependent on the bed reference elevation and method of computation used. Surveys of the channel bed near the bridge piers indicate the horizontal location of lowest bed elevation (maximum depth of scour) may vary at least 17 ft between different surveys at the same pier and most frequently is located downstream from the upstream face of the pier.

Pliocene oceanic seaways and global climate.

PubMed

Karas, Cyrus; Nürnberg, Dirk; Bahr, André; Groeneveld, Jeroen; Herrle, Jens O; Tiedemann, Ralf; deMenocal, Peter B

2017-01-05

Tectonically induced changes in oceanic seaways had profound effects on global and regional climate during the Late Neogene. The constriction of the Central American Seaway reached a critical threshold during the early Pliocene ~4.8-4 million years (Ma) ago. Model simulations indicate the strengthening of the Atlantic Meridional Overturning Circulation (AMOC) with a signature warming response in the Northern Hemisphere and cooling in the Southern Hemisphere. Subsequently, between ~4-3 Ma, the constriction of the Indonesian Seaway impacted regional climate and might have accelerated the Northern Hemisphere Glaciation. We here present Pliocene Atlantic interhemispheric sea surface temperature and salinity gradients (deduced from foraminiferal Mg/Ca and stable oxygen isotopes, δ 18 O) in combination with a recently published benthic stable carbon isotope (δ 13 C) record from the southernmost extent of North Atlantic Deep Water to reconstruct gateway-related changes in the AMOC mode. After an early reduction of the AMOC at ~5.3 Ma, we show in agreement with model simulations of the impacts of Central American Seaway closure a strengthened AMOC with a global climate signature. During ~3.8-3 Ma, we suggest a weakening of the AMOC in line with the global cooling trend, with possible contributions from the constriction of the Indonesian Seaway.

Joule heating effects on electroosmotic flow in insulator-based dielectrophoresis.

PubMed

Sridharan, Sriram; Zhu, Junjie; Hu, Guoqing; Xuan, Xiangchun

2011-09-01

Insulator-based dielectrophoresis (iDEP) is an emerging technology that has been successfully used to manipulate a variety of particles in microfluidic devices. However, due to the locally amplified electric field around the in-channel insulator, Joule heating often becomes an unavoidable issue that may disturb the electroosmotic flow and affect the particle motion. This work presents the first experimental study of Joule heating effects on electroosmotic flow in a typical iDEP device, e.g., a constriction microchannel, under DC-biased AC voltages. A numerical model is also developed to simulate the observed flow pattern by solving the coupled electric, energy, and fluid equations in a simplified two-dimensional geometry. It is observed that depending on the magnitude of the DC voltage, a pair of counter-rotating fluid circulations can occur at either the downstream end alone or each end of the channel constriction. Moreover, the pair at the downstream end appears larger in size than that at the upstream end due to DC electroosmotic flow. These fluid circulations, which are reasonably simulated by the numerical model, form as a result of the action of the electric field on Joule heating-induced fluid inhomogeneities in the constriction region. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Modeling the acoustics of American English /r/ using configurable articulatory synthesis (CASY)

NASA Astrophysics Data System (ADS)

Lehnert-Lehouillier, Heike; Iskarous, Khalil; Whalen, Douglas H.

2004-05-01

The claim that articulatory variation in /r/ production exhibits systematic tradeoffs to achieve a stable acoustic signal (Guenther et al., 1999) was tested using configurable articulatory synthesis (CASY) and ultrasound data. In particular, the hypothesis was tested that multiple constrictions during /r/ production are necessary to achieve a low enough F3. Ultrasound and Optotrak data from four speakers pronouncing /r/ in different vocalic contexts were used to determine where in the vocal tract the tongue gestures are placed. This data was then modeled using CASY parameters and was used to determine how the three gestures in /r/ (labial, palatal, and pharyngeal) contribute to the F3 value observed in the speech signal simultaneously recorded with the ultrasound. This was done by varying the degree and location of the lingual constrictions and the degree of the labial constriction and determining the effect on F3. It was determined that the three gestures in /r/ contribute in differing amounts to the overall F3 lowering. Furthermore, it does not seem that all three gestures are necessary for F3 lowering. This lends support to the hypothesis that the goal in /r/ production is the simultaneous achievement of three gestures. [Work supported by NIH Grant DC-02717.

Molecular mechanisms underlying the effects of acupuncture on neuropathic pain

PubMed Central

Ju, Ziyong; Cui, Huashun; Guo, Xiaohui; Yang, Huayuan; He, Jinsen; Wang, Ke

2013-01-01

Acupuncture has been used to treat neuropathic pain for a long time, but its mechanisms of action remain unknown. In this study, we observed the effects of electroacupuncture and manual acu-puncture on neuropathic pain and on ephrin-B/EphB signaling in rats models of chronic constriction injury-induced neuropathic pain. The results showed that manual acupuncture and elec-puncture significantly reduced mechanical hypersensitivity following chronic constriction injury, es-pecially electroacupuncture treatment. Real-time PCR results revealed that ephrin-B1/B3 and EphB1/B2 mRNA expression levels were significantly increased in the spinal dorsal horns of chronic constriction injury rats. Electroacupuncture and manual acupuncture suppressed the high sion of ephrin-B1 mRNA, and elevated EphB3/B4 mRNA expression. Electroacupuncture signifi-cantly enhanced the mRNA expression of ephrin-B3 and EphB3/B6 in the dorsal horns of neuro-pathic pain rats. Western blot results revealed that electroacupuncture in particular, and manual acupuncture, significantly up-regulated ephrin-B3 protein levels in rat spinal dorsal horns. The re-sults of this study suggest that acupuncture could activate ephrin-B/EphB signaling in neuropathic pain rats and improve neurological function. PMID:25206545

Modeling the interactions between compliant microcapsules and pillars in microchannels

NASA Astrophysics Data System (ADS)

Zhu, Guangdong; Alexeev, Alexander; Kumacheva, Eugenia; Balazs, Anna C.

2007-07-01

Using a computational model, we investigate the motion of microcapsules inside a microchannel that encompasses a narrow constriction. The microcapsules are composed of a compliant, elastic shell and an encapsulated fluid; these fluid-filled shells model synthetic polymeric microcapsules or biological cells (e.g., leukocytes). Driven by an imposed flow, the capsules are propelled along the microchannel and through the constricted region, which is formed by two pillars that lie in registry, extending from the top and bottom walls of the channels. The tops of these pillars (facing into the microchannel) are modified to exhibit either a neutral or an attractive interaction with the microcapsules. The pillars (and constriction) model topological features that can be introduced into microfluidic devices or the physical and chemical heterogeneities that are inherently present in biological vessels. To simulate the behavior of this complex system, we employ a hybrid method that integrates the lattice Boltzmann model (LBM) for fluid dynamics and the lattice spring model (LSM) for the micromechanics of elastic solids. Through this LBM/LSM technique, we probe how the capsule's stiffness and interaction with the pillars affect its passage through the chambers. The results yield guidelines for regulating the movement of microcarriers in microfluidic systems and provide insight into the flow properties of biological cells in capillaries.

Molecular mechanisms underlying the effects of acupuncture on neuropathic pain.

PubMed

Ju, Ziyong; Cui, Huashun; Guo, Xiaohui; Yang, Huayuan; He, Jinsen; Wang, Ke

2013-09-05

Acupuncture has been used to treat neuropathic pain for a long time, but its mechanisms of action remain unknown. In this study, we observed the effects of electroacupuncture and manual acu-puncture on neuropathic pain and on ephrin-B/EphB signaling in rats models of chronic constriction injury-induced neuropathic pain. The results showed that manual acupuncture and elec-puncture significantly reduced mechanical hypersensitivity following chronic constriction injury, es-pecially electroacupuncture treatment. Real-time PCR results revealed that ephrin-B1/B3 and EphB1/B2 mRNA expression levels were significantly increased in the spinal dorsal horns of chronic constriction injury rats. Electroacupuncture and manual acupuncture suppressed the high sion of ephrin-B1 mRNA, and elevated EphB3/B4 mRNA expression. Electroacupuncture signifi-cantly enhanced the mRNA expression of ephrin-B3 and EphB3/B6 in the dorsal horns of neuro-pathic pain rats. Western blot results revealed that electroacupuncture in particular, and manual acupuncture, significantly up-regulated ephrin-B3 protein levels in rat spinal dorsal horns. The re-sults of this study suggest that acupuncture could activate ephrin-B/EphB signaling in neuropathic pain rats and improve neurological function.

Efficacy of paracetamol on patent ductus arteriosus closure may be dose dependent: evidence from human and murine studies.

PubMed

El-Khuffash, Afif; Jain, Amish; Corcoran, David; Shah, Prakesh S; Hooper, Christopher W; Brown, Naoko; Poole, Stanley D; Shelton, Elaine L; Milne, Ginger L; Reese, Jeff; McNamara, Patrick J

2014-09-01

We evaluated the clinical effectiveness of variable courses of paracetamol on patent ductus arteriosus (PDA) closure and examined its effect on the in vitro term and preterm murine ductus arteriosus (DA). Neonates received one of the following three paracetamol regimens: short course of oral paracetamol (SCOP), long course of oral paracetamol (LCOP), and intravenous paracetamol (IVP) for 2-6 d. Pressure myography was used to examine changes in vasomotor tone of the preterm and term mouse DA in response to paracetamol or indomethacin. Their effect on prostaglandin synthesis by DA explants was measured by mass spectroscopy. Twenty-one preterm infants were included. No changes in PDA hemodynamics were seen in SCOP infants (n = 5). The PDA became less significant and eventually closed in six LCOP infants (n = 7). PDA closure was achieved in eight IVP infants (n = 9). On pressure myograph, paracetamol induced a concentration-dependent constriction of the term mouse DA, up to 30% of baseline (P < 0.01), but required >1 µmol/l. Indomethacin induced greater DA constriction and suppression of prostaglandin synthesis (P < 0.05). The clinical efficacy of paracetamol on PDA closure may depend on the duration of treatment and the mode of administration. Paracetamol is less potent than indomethacin for constriction of the mouse DA in vitro.

Effects of melatonin on rat pial arteriolar diameter in vivo

PubMed Central

Régrigny, Olivier; Delagrange, Philippe; Scalbert, Elizabeth; Lartaud-Idjouadiene, Isabelle; Atkinson, Jeffrey; Chillon, Jean-Marc

1999-01-01

Based on our finding that melatonin decreased the lower limit of cerebral blood flow autoregulation in rat, we previously suggested that melatonin constricts cerebral arterioles. The goal of this study was to demonstrate this vasoconstrictor action and investigate the mechanisms involved.The effects of cumulative doses of melatonin (10−10 to 10−6 M) were examined in cerebral arterioles (30–50 μM) of male Wistar rats using an open skull preparation. Cerebral arterioles were exposed to two doses of melatonin (3×10−9 and 3×10−8 M) in the absence and presence of the mt1 and/or MT2 receptor antagonist, luzindole (2×10−6 M) and the Ca2+-activated K+ (BKCa) channel blocker, tetraethylammonium (TEA+, 10−4 M). The effect of L-nitro arginine methyl ester (L-NAME, 10−8 M) was examined on arterioles after TEA+ superfusion. Cerebral arterioles were also exposed to the BKCa activator, NS1619 (10−5 M), and to sodium nitroprusside (SNP, 10−8 M) in the absence and presence of melatonin (3×10−8 M).Melatonin induced a dose-dependent constriction with an EC50 of 3.0±0.1 nM and a maximal constriction of −15±1%. Luzindole abolished melatonin-induced vasoconstriction. TEA+ induced significant vasoconstriction (−10±2%). No additional vasoconstriction was observed when melatonin was added to the aCSF in presence of TEA+, whereas L-NAME still induced vasoconstriction (−10±1%). NS1619 induced vasodilatation (+11±1%) which was 50% less in presence of melatonin. Vasodilatation induced by SNP (+12±2%) was not diminished by melatonin.Melatonin directly constricts small diameter cerebral arterioles in rats. This vasoconstrictor effect is mediated by inhibition of BKCa channels following activation of mt1 and/or MT2 receptors. PMID:10455324

Development of a microfluidic device for cell concentration and blood cell-plasma separation.

PubMed

Maria, M Sneha; Kumar, B S; Chandra, T S; Sen, A K

2015-12-01

This work presents design, fabrication and test of a microfluidic device which employs Fahraeus-Lindqvist and Zweifach-Fung effects for cell concentration and blood cell-plasma separation. The device design comprises a straight main channel with a series of branched channels placed symmetrically on both sides of the main channel. The design implements constrictions before each junction (branching point) in order to direct cells that would have migrated closer to the wall (naturally or after liquid extraction at a junction) towards the centre of the main channel. Theoretical and numerical analysis are performed for design of the microchannel network to ensure that a minimum flow rate ratio (of 2.5:1, main channel-to-side channels) is maintained at each junction and predict flow rate at the plasma outlet. The dimensions and location of the constrictions were determined using numerical simulations. The effect of presence of constrictions before the junctions was demonstrated by comparing the performances of the device with and without constrictions. To demonstrate the performance of the device, initial experiments were performed with polystyrene microbeads (10 and 15 μm size) and droplets. Finally, the device was used for concentration of HL60 cells and separation of plasma and cells in diluted blood samples. The cell concentration and blood-plasma purification efficiency was quantified using Haemocytometer and Fluorescence-Activated Cell Sorter (FACS). A seven-fold cell concentration was obtained with HL60 cells and a purification efficiency of 70 % and plasma recovery of 80 % was observed for diluted (1:20) blood sample. FACS was used to identify cell lysis and the cell viability was checked using Trypan Blue test which showed that more than 99 % cells are alive indicating the suitability of the device for practical use. The proposed device has potential to be used as a sample preparation module in lab on chip based diagnostic platforms.

Centromeres Off the Hook: Massive Changes in Centromere Size and Structure Following Duplication of CenH3 Gene in Fabeae Species.

PubMed

Neumann, Pavel; Pavlíková, Zuzana; Koblížková, Andrea; Fuková, Iva; Jedličková, Veronika; Novák, Petr; Macas, Jiří

2015-07-01

In most eukaryotes, centromere is determined by the presence of the centromere-specific histone variant CenH3. Two types of chromosome morphology are generally recognized with respect to centromere organization. Monocentric chromosomes possess a single CenH3-containing domain in primary constriction, whereas holocentric chromosomes lack the primary constriction and display dispersed distribution of CenH3. Recently, metapolycentric chromosomes have been reported in Pisum sativum, representing an intermediate type of centromere organization characterized by multiple CenH3-containing domains distributed across large parts of chromosomes that still form a single constriction. In this work, we show that this type of centromere is also found in other Pisum and closely related Lathyrus species, whereas Vicia and Lens genera, which belong to the same legume tribe Fabeae, possess only monocentric chromosomes. We observed extensive variability in the size of primary constriction and the arrangement of CenH3 domains both between and within individual Pisum and Lathyrus species, with no obvious correlation to genome or chromosome size. Search for CenH3 gene sequences revealed two paralogous variants, CenH3-1 and CenH3-2, which originated from a duplication event in the common ancestor of Fabeae species. The CenH3-1 gene was subsequently lost or silenced in the lineage leading to Vicia and Lens, whereas both genes are retained in Pisum and Lathyrus. Both of these genes appear to have evolved under purifying selection and produce functional CenH3 proteins which are fully colocalized. The findings described here provide the first evidence for a highly dynamic centromere structure within a group of closely related species, challenging previous concepts of centromere evolution. © The Author 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

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

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.

[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.

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. PMID:28298491

Toll‐Like Receptor‐2 Mediates Adaptive Cardiac Hypertrophy in Response to Pressure Overload Through Interleukin‐1β Upregulation via Nuclear Factor κB Activation

PubMed Central

Higashikuni, Yasutomi; Tanaka, Kimie; Kato, Megumi; Nureki, Osamu; Hirata, Yasunobu; Nagai, Ryozo; Komuro, Issei; Sata, Masataka

2013-01-01

Background Inflammation is induced in the heart during the development of cardiac hypertrophy. The initiating mechanisms and the role of inflammation in cardiac hypertrophy, however, remain unclear. Toll‐like receptor‐2 (TLR2) recognizes endogenous molecules that induce noninfectious inflammation. Here, we examined the role of TLR2‐mediated inflammation in cardiac hypertrophy. Methods and Results At 2 weeks after transverse aortic constriction, Tlr2−/− mice showed reduced cardiac hypertrophy and fibrosis with greater left ventricular dilatation and impaired systolic function compared with wild‐type mice, which indicated impaired cardiac adaptation in Tlr2−/− mice. Bone marrow transplantation experiment revealed that TLR2 expressed in the heart, but not in bone marrow–derived cells, is important for cardiac adaptive response to pressure overload. In vitro experiments demonstrated that TLR2 signaling can induce cardiomyocyte hypertrophy and fibroblast and vascular endothelial cell proliferation through nuclear factor–κB activation and interleukin‐1β upregulation. Systemic administration of a nuclear factor–κB inhibitor or anti–interleukin‐1β antibodies to wild‐type mice resulted in impaired adaptive cardiac hypertrophy after transverse aortic constriction. We also found that heat shock protein 70, which was increased in murine plasma after transverse aortic constriction, can activate TLR2 signaling in vitro and in vivo. Systemic administration of anti–heat shock protein 70 antibodies to wild‐type mice impaired adaptive cardiac hypertrophy after transverse aortic constriction. Conclusions Our results demonstrate that TLR2‐mediated inflammation induced by extracellularly released heat shock protein 70 is essential for adaptive cardiac hypertrophy in response to pressure overload. Thus, modulation of TLR2 signaling in the heart may provide a novel strategy for treating heart failure due to inadequate adaptation to hemodynamic stress. PMID:24249711

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 grafting and stable results.

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 interpreted as nonspecific. The relative loss of bronchioles and the relationship of the scars to contiguous arteries should signal the need for elastic stains to look for the residual elastica of the bronchioles amidst the foci of fibrosis. Increasingly, clinical grounds, including pulmonary functions studies and high-resolution computed tomography findings, are proving to be relatively sensitive methods of detecting CB. Finally, the progressive airway destruction in chronic transplantation rejection appears to be a T-cell-mediated process. The "active" form of constrictive bronchiolitis, with attendant lymphocytic inflammation of the airways, likely precedes the "inactive" or scarred form of constrictive bronchiolitis.

Calculation of exchange coupling constants in triply-bridged dinuclear Cu(II) compounds based on spin-flip constricted variational density functional theory.

PubMed

Seidu, Issaka; Zhekova, Hristina R; Seth, Michael; Ziegler, Tom

2012-03-08

The performance of the second-order spin-flip constricted variational density functional theory (SF-CV(2)-DFT) for the calculation of the exchange coupling constant (J) is assessed by application to a series of triply bridged Cu(II) dinuclear complexes. A comparison of the J values based on SF-CV(2)-DFT with those obtained by the broken symmetry (BS) DFT method and experiment is provided. It is demonstrated that our methodology constitutes a viable alternative to the BS-DFT method. The strong dependence of the calculated exchange coupling constants on the applied functionals is demonstrated. Both SF-CV(2)-DFT and BS-DFT affords the best agreement with experiment for hybrid functionals.

Severe Adult-onset Still Disease with Constrictive Pericarditis and Pleuritis That Was Successfully Treated with Tocilizumab in Addition to Corticosteroids and Cyclosporin A.

PubMed

Kawaguchi, Hoshimi; Tsuboi, Hiroto; Yagishita, Mizuki; Terasaki, Toshihiko; Terasaki, Mayu; Shimizu, Masaru; Honda, Fumika; Ohyama, Ayako; Takahashi, Hiroyuki; Miki, Haruka; Yokosawa, Masahiro; Asashima, Hiromitsu; Hagiwara, Shinya; Kondo, Yuya; Matsumoto, Isao; Sumida, Takayuki

2018-04-01

Adult-onset Still disease (AOSD) is a systemic inflammatory disease characterized by fever, arthritis and rash. Corticosteroids represent a promising therapeutic option for AOSD; however, some resistant cases require immunosuppressants and biologic agents. We herein report the case of a 29-year-old Japanese man with severe AOSD, accompanied by constrictive pericarditis (CP) and pleuritis. Although 2 courses of steroid pulse and subsequent high-dose of prednisolone and cyclosporine A improved the patient's CP and pleuritis, his fever and inflammatory responses persisted. Tocilizumab (TCZ) was added to his treatment, which resulted in a rapid remission. This case suggests the usefulness of TCZ in the treatment of severe AOSD with CP and pleuritis.

Cook stove assembly

DOEpatents

DeFoort, Morgan W; Willson, Bryan D; Lorenz, Nathan; Brady, Michael P; Marchese, Anthony; Miller-Lionberg, Daniel D

2014-12-02

A combustion chamber, having an upper part and a lower part, may include an annular constriction, in combination with the combustion chamber, to aid in directing partially combusted gases such as carbon monoxide away from the periphery of the combustion chamber back toward its center, and into the flame front. The annular constriction may also impede the flow of partially combusted gases located at the periphery, thus increasing the time these gases spend within the combustion chamber and increasing the likelihood that any products of incomplete combustion will undergo combustion. The combustion chamber may further comprise a dual burner cooktop for directing combustion gases and exhaust to multiple cooking vessels. In further embodiments, the combustion chamber may be made of, lined, or clad with a metal alloy comprising iron, chromium, and aluminum.

A laryngographic and laryngoscopic study of Northern Vietnamese tones.

PubMed

Brunelle, Marc; Nguyên, Duy Duong; Nguyên, Khac Hùng

2010-01-01

A laryngographic and laryngoscopic study of tone production in Northern Vietnamese, a language whose tones combine both fundamental frequency (f0) modulations and voice qualities (phonation types), was conducted with 5 male and 5 female speakers. Results show that the f0 contours of Northern Vietnamese tones are not only attributable to changes in vocal fold length and tension (partly through changes in larynx height), but that f0 drops are also largely caused by the glottal configurations responsible for the contrastive voice qualities associated with some of the tones. We also find that voice quality contrasts are mostly due to glottal constriction: they occasionally involve additional ventricular fold incursion and epiglottal constriction, but these articulations are usually absent. Copyright © 2010 S. Karger AG, Basel.

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.

[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.

Ainhum - A Rare Case Report.

PubMed

Prabhu, Ravi; Kannan, Narayanasamy Subbaraju; Vinoth, Sundaresan; Praveen, Chinnappan Balasubramanian

2016-04-01

The term 'AINHUM' is derived from the African word meaning 'to saw or cut'. True ainhum otherwise called dactylolysis spontanea is a condition involving soft tissue or digits with constricting rings commonly presenting in fifth toes, usually bilateral. It is to be differentiated from Pseudo-ainhum that occurs secondary to some hereditary and nonhereditary diseases that lead to annular constriction of digits. We report a rare case of true ainhum involving the left fourth toe only. It is a very rare case and a very few were reported worldwide. The highest incidence of ainhum has been reported in South Africa and South America. It is rarely reported in India. Ainhum when diagnosed and treated in early stages can be prevented from progressing to mutilating deformities.

The Prebiotic Inulin Aggravates Accelerated Atherosclerosis in Hypercholesterolemic APOE*3-Leiden Mice.

PubMed

Hoving, Lisa R; de Vries, Margreet R; de Jong, Rob C M; Katiraei, Saeed; Pronk, Amanda; Quax, Paul H A; van Harmelen, Vanessa; Willems van Dijk, Ko

2018-02-03

The prebiotic inulin has proven effective at lowering inflammation and plasma lipid levels. As atherosclerosis is provoked by both inflammation and hyperlipidemia, we aimed to determine the effect of inulin supplementation on atherosclerosis development in hypercholesterolemic APOE*3-Leiden ( E3L ) mice. Male E3L mice were fed a high-cholesterol (1%) diet, supplemented with or without 10% inulin for 5 weeks. At week 3, a non-constrictive cuff was placed around the right femoral artery to induce accelerated atherosclerosis. At week 5, vascular pathology was determined by lesion thickness, vascular remodeling, and lesion composition. Throughout the study, plasma lipids were measured and in week 5, blood monocyte subtypes were determined using flow cytometry analysis. In contrast to our hypothesis, inulin exacerbated atherosclerosis development, characterized by increased lesion formation and outward vascular remodeling. The lesions showed increased number of macrophages, smooth muscle cells, and collagen content. No effects on blood monocyte composition were found. Inulin significantly increased plasma total cholesterol levels and total cholesterol exposure. In conclusion, inulin aggravated accelerated atherosclerosis development in hypercholesterolemic E3L mice, accompanied by adverse lesion composition and outward remodeling. This process was not accompanied by differences in blood monocyte composition, suggesting that the aggravated atherosclerosis development was driven by increased plasma cholesterol.

The Prebiotic Inulin Aggravates Accelerated Atherosclerosis in Hypercholesterolemic APOE*3-Leiden Mice

PubMed Central

de Jong, Rob C. M.; Katiraei, Saeed; Pronk, Amanda; van Harmelen, Vanessa

2018-01-01

The prebiotic inulin has proven effective at lowering inflammation and plasma lipid levels. As atherosclerosis is provoked by both inflammation and hyperlipidemia, we aimed to determine the effect of inulin supplementation on atherosclerosis development in hypercholesterolemic APOE*3-Leiden (E3L) mice. Male E3L mice were fed a high-cholesterol (1%) diet, supplemented with or without 10% inulin for 5 weeks. At week 3, a non-constrictive cuff was placed around the right femoral artery to induce accelerated atherosclerosis. At week 5, vascular pathology was determined by lesion thickness, vascular remodeling, and lesion composition. Throughout the study, plasma lipids were measured and in week 5, blood monocyte subtypes were determined using flow cytometry analysis. In contrast to our hypothesis, inulin exacerbated atherosclerosis development, characterized by increased lesion formation and outward vascular remodeling. The lesions showed increased number of macrophages, smooth muscle cells, and collagen content. No effects on blood monocyte composition were found. Inulin significantly increased plasma total cholesterol levels and total cholesterol exposure. In conclusion, inulin aggravated accelerated atherosclerosis development in hypercholesterolemic E3L mice, accompanied by adverse lesion composition and outward remodeling. This process was not accompanied by differences in blood monocyte composition, suggesting that the aggravated atherosclerosis development was driven by increased plasma cholesterol. PMID:29401645

Hypoxia potentiates microRNA-mediated gene silencing through posttranslational modification of Argonaute2.

PubMed

Wu, Connie; So, Jessica; Davis-Dusenbery, Brandi N; Qi, Hank H; Bloch, Donald B; Shi, Yang; Lagna, Giorgio; Hata, Akiko

2011-12-01

Hypoxia contributes to the pathogenesis of various human diseases, including pulmonary artery hypertension (PAH), stroke, myocardial or cerebral infarction, and cancer. For example, acute hypoxia causes selective pulmonary artery (PA) constriction and elevation of pulmonary artery pressure. Chronic hypoxia induces structural and functional changes to the pulmonary vasculature, which resembles the phenotype of human PAH and is commonly used as an animal model of this disease. The mechanisms that lead to hypoxia-induced phenotypic changes have not been fully elucidated. Here, we show that hypoxia increases type I collagen prolyl-4-hydroxylase [C-P4H(I)], which leads to prolyl-hydroxylation and accumulation of Argonaute2 (Ago2), a critical component of the RNA-induced silencing complex (RISC). Hydroxylation of Ago2 is required for the association of Ago2 with heat shock protein 90 (Hsp90), which is necessary for the loading of microRNAs (miRNAs) into the RISC, and translocation to stress granules (SGs). We demonstrate that hydroxylation of Ago2 increases the level of miRNAs and increases the endonuclease activity of Ago2. In summary, this study identifies hypoxia as a mediator of the miRNA-dependent gene silencing pathway through posttranslational modification of Ago2, which might be responsible for cell survival or pathological responses under low oxygen stress.

Cardiac overexpression of Mammalian enabled (Mena) exacerbates heart failure in mice

PubMed Central

Belmonte, Stephen L.; Ram, Rashmi; Mickelsen, Deanne M.; Gertler, Frank B.

2013-01-01

Mammalian enabled (Mena) is a key regulator of cytoskeletal actin dynamics, which has been implicated in heart failure (HF). We have previously demonstrated that cardiac Mena deletion produced cardiac dysfunction with conduction abnormalities and hypertrophy. Moreover, elevated Mena expression correlates with HF in human and animal models, yet the precise role of Mena in cardiac pathophysiology is unclear. In these studies, we evaluated mice with cardiac myocyte-specific Mena overexpression (TTA/TgTetMena) comparable to that observed in cardiac pathology. We found that the hearts of TTA/TgTetMena mice were functionally and morphologically comparable to wild-type littermates, except for mildly increased heart mass in the transgenic mice. Interestingly, TTA/TgTetMena mice were particularly susceptible to cardiac injury, as these animals experienced pronounced decreases in ejection fraction and fractional shortening as well as heart dilatation and hypertrophy after transverse aortic constriction (TAC). By “turning off” Mena overexpression in TTA/TgTetMena mice either immediately prior to or immediately after TAC surgery, we discovered that normalizing Mena levels eliminated cardiac hypertrophy in TTA/TgTetMena animals but did not preclude post-TAC cardiac functional deterioration. These findings indicate that hearts with increased levels of Mena fare worse when subjected to cardiac injury and suggest that Mena contributes to HF pathophysiology. PMID:23832697

Cardiac overexpression of Mammalian enabled (Mena) exacerbates heart failure in mice.

PubMed

Belmonte, Stephen L; Ram, Rashmi; Mickelsen, Deanne M; Gertler, Frank B; Blaxall, Burns C

2013-09-15

Mammalian enabled (Mena) is a key regulator of cytoskeletal actin dynamics, which has been implicated in heart failure (HF). We have previously demonstrated that cardiac Mena deletion produced cardiac dysfunction with conduction abnormalities and hypertrophy. Moreover, elevated Mena expression correlates with HF in human and animal models, yet the precise role of Mena in cardiac pathophysiology is unclear. In these studies, we evaluated mice with cardiac myocyte-specific Mena overexpression (TTA/TgTetMena) comparable to that observed in cardiac pathology. We found that the hearts of TTA/TgTetMena mice were functionally and morphologically comparable to wild-type littermates, except for mildly increased heart mass in the transgenic mice. Interestingly, TTA/TgTetMena mice were particularly susceptible to cardiac injury, as these animals experienced pronounced decreases in ejection fraction and fractional shortening as well as heart dilatation and hypertrophy after transverse aortic constriction (TAC). By "turning off" Mena overexpression in TTA/TgTetMena mice either immediately prior to or immediately after TAC surgery, we discovered that normalizing Mena levels eliminated cardiac hypertrophy in TTA/TgTetMena animals but did not preclude post-TAC cardiac functional deterioration. These findings indicate that hearts with increased levels of Mena fare worse when subjected to cardiac injury and suggest that Mena contributes to HF pathophysiology.

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 PLSVC variant presents with persistent, unexplained hypoxia or cyanosis and embolisation causing recurrent transient ischemic attacks and/or cerebral abscesses. This PLSVC variant is more often associated with absence of the right SVC and congenital heart abnormalities.

Hemodynamic, pulmonary vascular, and myocardial abnormalities secondary to pharmacologic constriction of the fetal ductus arteriosus. A possible mechanism for persistent pulmonary hypertension and transient tricuspid insufficiency in the newborn infant.

PubMed

Levin, D L; Mills, L J; Weinberg, A G

1979-08-01

The prostaglandin synthetase inhibitor indomethacin was given orally or intravenously to pregnant ewes. This resulted in a significant rise in the fetal pulmonary-to-systemic arterial mean blood pressure difference across the ductus arteriosus, presumably secondary to constriction of the ductus arteriosus. In five experiments the pressure difference could be promptly but temporarily reversed by the administration of prostaglandin E1 (PGE1) into the fetal inferior vena cava. Fetal lungs from study and control animals were fixed by perfusion at measured pulmonary arterial mean blood pressure, and fifth-generation resistance vessels were studied. The medial width/external diameter ratio was significantly increased in the study vs the control lungs due to increased smooth muscle and decreased external diameter. In addition, study fetuses had acute degenerative myocardial changes in the tricuspid valve papillary muscles, the right ventricular free wall and the interventricular septum. Similar changes were not seen in control fetuses. Indomethacin administration during pregnancy causes constriction of the fetal ductus arteriosus, fetal pulmonary arterial hypertension, and right ventricular damage. If severe, this may cause rapid fetal death. If less severe, in the newborn infant, this mechanism may be one cause of persistent pulmonary hypertension due to vasoconstriction and increased pulmonary arterial smooth muscle and/or tricuspid insufficiency due to papillary muscle infarction.

Comparison of effectiveness and safety of operations on the pericardium

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

Palatianos, G.M.; Thurer, R.J.; Kaiser, G.A.

1985-07-01

A ten-year experience with operations on the pericardium in 71 consecutive patients was reviewed. The patients ranged in age from nine months to 75 years old. Fifty-three patients were operated upon for pericardial effusion and 14 for pericardial constriction. Sixty-seven patients had pericarditis: 21 of them underwent subxiphoid tube drainage; ten, limited pericardiectomy; and the remaining 36, extensive pericardiectomy. There were two trauma victims who underwent diagnostic pericardiotomy. Two patients underwent excision of pericardial cysts. There was one operative death during extensive pericardiectomy for constrictive tuberculous pericarditis. Thirty-day mortality was three of 21 patients after subxiphoid tube drainage, three ofmore » ten after limited pericardiectomy and five of 36 after extensive pericardiectomy. Postoperative complications consisted of pulmonary problems in four patients (two after pericardiectomy and two after extensive pericardiectomy), cardiac arrhythmia in one patient after tube drainage and postpericardiotomy syndrome in one patient after extensive pericardiectomy. Mean follow-up was 3.2 years. Recurrent pericardial effusion occurred in two patients; one had limited pericardiectomy but did not require reoperation and one had diagnostic pericardiotomy without drainage. Six patients with persistent postirradiation pericardial effusion were treated effectively with extensive pericardiotomy. Experience indicates that subxiphoid tube drainage is effective for the treatment of pericardial effusion and safer than limited pericardiectomy, while extensive pericardiectomy is the operation of choice for pericardial constriction and radiation-related pericardial effusion.« less

Glomerular prostaglandins modulate vascular reactivity of the downstream efferent arterioles.

PubMed

Arima, S; Ren, Y; Juncos, L A; Carretero, O A; Ito, S

1994-03-01

The balance of vascular resistance in afferent (Af-) and efferent arterioles (Ef-Arts) is a crucial factor that determines glomerular hemodynamics. We have recently reported that when Ef-Arts were perfused from the distal end of the Af-Art through the glomerulus (orthograde perfusion; OP), both angiotensin II (Ang II) and norepinephrine (NE) induced much weaker constriction than they did when Ef-Arts were perfused from the distal end (retrograde perfusion; RP). This difference was not affected by inhibiting synthesis of nitric oxide. In the present study, we tested the hypothesis that glomerular prostaglandins (PGs) may modulate vascular reactivity of the downstream Ef-Art. In addition, we examined the possible modulatory role of PGs in the Af-Art responses to Ang II or NE. Both Ang II and NE caused dose-dependent constriction of Ef-Arts with either OP or RP; however, the constriction was stronger in RP. At 10(-8) M, Ang II decreased Ef-Art diameter by 35 +/- 3.5% in OP (N = 9) compared to 73 +/- 3.9% in RP (N = 5), while 10(-6) M NE decreased the diameter by 25 +/- 3.6% in OP (N = 9) compared to 62 +/- 7.2% in RP (N = 5). Pretreatment with 5 x 10(-5) M indomethacin (Indo) did not alter basal diameter with either method of perfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

The Role of Microfilaments in Early Meiotic Maturation of Mouse Oocytes

NASA Astrophysics Data System (ADS)

Calarco, Patricia G.

2005-04-01

Mouse oocyte microfilaments (MF) were perturbed by depolymerization (cytochalasin B) or stabilization (jasplakinolide) and correlated meiotic defects examined by confocal microscopy. MF, microtubules, and mitochondria were vitally stained; centrosomes ([gamma]-tubulin), after fixation. MF depolymerization by cytochalasin in culture medium did not affect central migration of centrosomes, mitochondria, or nuclear breakdown (GVBD); some MF signal was localized around the germinal vesicle (GV). In maturation-blocking medium (containing IBMX), central movement was curtailed and cortical MF aggregations made the plasma membrane wavy. Occasional long MF suggested that not all MF were depolymerized. MF stabilization by jasplakinolide led to MF aggregations throughout the cytoplasm. GVBD occurred (unless IBMX was present) but no spindle formed. Over time, most oocytes constricted creating a dumbbell shape with MF concentrated under one-half of the oocyte cortex and on either side of the constriction. In IBMX medium, the MF-containing half of the dumbbell over time sequestered the GV, MF, mitochondria, and one to two large cortical centrosomes; the non-MF half appeared empty. Cumulus processes contacted the oocyte surface (detected by microtubule content) and mirrored MF distribution. Results demonstrated that MF play an essential role in meiosis, primarily through cortically mediated events, including centrosome localization, spindle (or GV) movement to the periphery, activation of (polar body) constriction, and establishment of oocyte polarity. The presence of a cortical “organizing pole” is hypothesized.

An Anatomical Assessment of Branch Abscission and Branch-base Hydraulic Architecture in the Endangered Wollemia nobilis

PubMed Central

Burrows, G. E.; Meagher, P. F.; Heady, R. D.

2007-01-01

Background and Aims The branch-base xylem structure of the endangered Wollemia nobilis was anatomically investigated. Wollemia nobilis is probably the only extant tree species that produces only first-order branches and where all branches are cleanly abscised. An investigation was carried out to see if these unusual features might influence branch-base xylem structure and water supply to the foliage. Methods The xylem was sectioned at various distances along the branch bases of 6-year-old saplings. Huber values and relative theoretical hydraulic conductivities were calculated for various regions of the branch base. Key Results The most proximal branch base featured a pronounced xylem constriction. The constriction had only 14–31 % (average 21 %) of the cross-sectional area and 20–42 % (average 28 %) of the theoretical hydraulic conductivity of the more distal branch xylem. Wollemia nobilis had extremely low Huber values for a conifer. Conclusions The branch-base xylem constriction would appear to facilitate branch abscission, while the associated Huber values show that W. nobilis supplies a relatively large leaf area through a relatively small diameter ‘pipe’. It is tempting to suggest that the pronounced decline of W. nobilis in the Tertiary is related to its unusual branch-base structure but physiological studies of whole plant conductance are still needed. PMID:17272303

Distribution and assessment of sediment toxicity in Tamaki Estuary, Auckland, New Zealand

NASA Astrophysics Data System (ADS)

Abrahim, G. M. S.; Parker, R. J.; Nichol, S. L.

2007-07-01

Heavy metal levels in surface sediments from Tamaki Estuary demonstrate significant up estuary increases in Cu, Pb, Zn, Cd and mud concentrations. Increased metal levels towards the head of the estuary are linked to local catchment sources reflecting the historical development, industrialisation and urbanisation of catchment areas surrounding the upper estuary. The relatively narrow constriction in the middle estuary (Panmure area), makes it susceptible to accumulation of upper estuary pollutants, since the constriction reduces circulation and extends the time required for fine waterborne sediments in the upper estuary to exchange with fresh coastal water. As a result fine fraction sediments trapped in the upper estuary facilitate capture and retention of pollutants at the head of the estuary. The increase in sandy mud poor sediments towards the mouth of the estuary is associated with generally low metal concentrations. The estuary’s geomorphic shape with a mid estuary constriction, sediment texture and mineralogy and catchment history are significant factors in understanding the overall spatial distribution of contaminants in the estuary. Bulk concentration values for Cu, Pb, Zn, and Cd in all the studied surface samples occur below ANZECC ISQG-H toxicity values. Cd and Cu concentrations are also below the ISQG-L toxicity levels for these elements. However, Pb and Zn concentrations do exceed the ISQG-L values in some of the surface bulk samples in the upper estuary proximal to long established sources of catchment pollution.

Contraction and stress-dependent growth shape the forebrain of the early chicken embryo.

PubMed

Garcia, Kara E; Okamoto, Ruth J; Bayly, Philip V; Taber, Larry A

2017-01-01

During early vertebrate development, local constrictions, or sulci, form to divide the forebrain into the diencephalon, telencephalon, and optic vesicles. These partitions are maintained and exaggerated as the brain tube inflates, grows, and bends. Combining quantitative experiments on chick embryos with computational modeling, we investigated the biophysical mechanisms that drive these changes in brain shape. Chemical perturbations of contractility indicated that actomyosin contraction plays a major role in the creation of initial constrictions (Hamburger-Hamilton stages HH11-12), and fluorescent staining revealed that F-actin is circumferentially aligned at all constrictions. A finite element model based on these findings shows that the observed shape changes are consistent with circumferential contraction in these regions. To explain why sulci continue to deepen as the forebrain expands (HH12-20), we speculate that growth depends on wall stress. This idea was examined by including stress-dependent growth in a model with cerebrospinal fluid pressure and bending (cephalic flexure). The results given by the model agree with observed morphological changes that occur in the brain tube under normal and reduced eCSF pressure, quantitative measurements of relative sulcal depth versus time, and previously published patterns of cell proliferation. Taken together, our results support a biphasic mechanism for forebrain morphogenesis consisting of differential contractility (early) and stress-dependent growth (late). Copyright © 2016 Elsevier Ltd. All rights reserved.

Efficacy of paracetamol on patent ductus arteriosus closure may be dose dependent: evidence from human and murine studies

PubMed Central

El-Khuffash, Afif; Jain, Amish; Corcoran, David; Shah, Prakesh S.; Hooper, Christopher W.; Brown, Naoko; Poole, Stanley D.; Shelton, Elaine L.; Milne, Ginger L.; Reese, Jeff

2015-01-01

BACKGROUND We evaluated the clinical effectiveness of variable courses of paracetamol on patent ductus arteriosus (PDA) closure and examined its effect on the in vitro term and preterm murine ductus arteriosus (DA). METHODS Neonates received one of the following three paracetamol regimens: short course of oral paracetamol (SCOP), long course of oral paracetamol (LCOP), and intravenous paracetamol (IVP) for 2–6 d. Pressure myography was used to examine changes in vasomotor tone of the preterm and term mouse DA in response to paracetamol or indomethacin. Their effect on prostaglandin synthesis by DA explants was measured by mass spectroscopy. RESULTS Twenty-one preterm infants were included. No changes in PDA hemodynamics were seen in SCOP infants (n = 5). The PDA became less significant and eventually closed in six LCOP infants (n = 7). PDA closure was achieved in eight IVP infants (n = 9). On pressure myograph, paracetamol induced a concentration-dependent constriction of the term mouse DA, up to 30% of baseline (P < 0.01), but required >1 μmol/l. Indomethacin induced greater DA constriction and suppression of prostaglandin synthesis (P < 0.05). CONCLUSION The clinical efficacy of paracetamol on PDA closure may depend on the duration of treatment and the mode of administration. Paracetamol is less potent than indomethacin for constriction of the mouse DA in vitro. PMID:24941212

Flexible particle flow-focusing in microchannel driven by droplet-directed induced-charge electroosmosis.

PubMed

Ren, Yukun; Liu, Xianyu; Liu, Weiyu; Tao, Ye; Jia, Yankai; Hou, Likai; Li, Wenying; Jiang, Hongyuan

2018-02-01

We report herein a novel microfluidic particle concentrator that utilizes constriction microchannels to enhance the flow-focusing performance of induced-charge electroosmosis (ICEO), where viscous hemi-spherical oil droplets are embedded within the mainchannel to form deformable converging-diverging constriction structures. The constriction region between symmetric oil droplets partially coated on the electrode strips can improve the focusing performance by inducing a granular wake flow area at the diverging channel, which makes almost all of the scattered sample particles trapped within a narrow stream on the floating electrode. Another asymmetric droplet pair arranged near the outlets can further direct the trajectory of focused particle stream to one specified outlet port depending on the symmetry breaking in the shape of opposing phase interfaces. By fully exploiting rectification properties of induced-charge electrokinetic phenomena at immiscible water/oil interfaces of tunable geometry, the expected function of continuous and switchable flow-focusing is demonstrated by preconcentrating both inorganic silica particles and biological yeast cells. Physical mechanisms responsible for particle focusing and locus deflection in the droplet-assisted concentrentor are analyzed in detail, and simulation results are in good accordance with experimental observations. Our work provides new routes to construct flexible electrokinetic framework for preprocessing on-chip biological samples before performing subsequent analysis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

PubMed Central

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

2013-01-01

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

Higher-Than-Ballistic Conduction in Viscous Electron Fluids

NASA Astrophysics Data System (ADS)

Levitov, Leonid

Strongly interacting electrons can move in a neatly coordinated way, reminiscent of the movement of viscous fluids. This talk will argue that in viscous flows interactions facilitate transport, allowing conductance to exceed the fundamental Sharvin-Landauer quantum-ballistic limit. The effect is particularly striking for the flow through a viscous point contact, a constriction exhibiting the quantum-mechanical ballistic transport at T = 0 but governed by electron hydrodynamics at elevated temperatures. Conductance grows as a square of the constriction width, i.e. faster than the linear width dependence for noninteracting fermions. The crossover between the ballistic and viscous regimes occurs when the mean free path for e-e collisions becomes comparable to the constriction width. Further, we will discuss the negative nonlocal response, a signature effect of viscous transport. This response exhibits an interesting nonmonotonic behavior vs. T at the viscous-to-balistic transition. The response is negative but small in the highly viscous regime at elevated temperatures. The value grows as the temperature is lowered and the system becomes less viscous, reaching the most negative values in the crossover region where the mean free path is comparable to the distance between contacts. Subsequently, it reverses sign at even lower temperatures, becoming positive as the system enters the ballistic regime. This peculiar behavior provides a clear signature of the ballistic-to-viscous transition and enables a direct measurement of the electron-electron collision mean free path.

DRhoGEF2 and Diaphanous Regulate Contractile Force during Segmental Groove Morphogenesis in the Drosophila Embryo

PubMed Central

Mulinari, Shai; Barmchi, Mojgan Padash

2008-01-01

Morphogenesis of the Drosophila embryo is associated with dynamic rearrangement of the actin cytoskeleton mediated by small GTPases of the Rho family. These GTPases act as molecular switches that are activated by guanine nucleotide exchange factors. One of these factors, DRhoGEF2, plays an important role in the constriction of actin filaments during pole cell formation, blastoderm cellularization, and invagination of the germ layers. Here, we show that DRhoGEF2 is equally important during morphogenesis of segmental grooves, which become apparent as tissue infoldings during mid-embryogenesis. Examination of DRhoGEF2-mutant embryos indicates a role for DRhoGEF2 in the control of cell shape changes during segmental groove morphogenesis. Overexpression of DRhoGEF2 in the ectoderm recruits myosin II to the cell cortex and induces cell contraction. At groove regression, DRhoGEF2 is enriched in cells posterior to the groove that undergo apical constriction, indicating that groove regression is an active process. We further show that the Formin Diaphanous is required for groove formation and strengthens cell junctions in the epidermis. Morphological analysis suggests that Dia regulates cell shape in a way distinct from DRhoGEF2. We propose that DRhoGEF2 acts through Rho1 to regulate acto-myosin constriction but not Diaphanous-mediated F-actin nucleation during segmental groove morphogenesis. PMID:18287521

Cocaine

MedlinePlus

... Short-term health effects of cocaine include: extreme happiness and energy mental alertness hypersensitivity to sight, sound, ... include: constricted blood vessels nausea faster heartbeat extreme happiness and energy irritability paranoia Long-term effects include: ...

Reconstitution of Contractile FtsZ Rings in Liposomes

PubMed Central

Osawa, Masaki; Anderson, David E.; Erickson, Harold P.

2009-01-01

FtsZ is a tubulin homolog and the major cytoskeletal protein in bacterial cell division. It assembles into the Z ring, which contains FtsZ and a dozen other division proteins, and constricts to divide the cell. We have constructed a membrane-targeted FtsZ (FtsZ-mts) by splicing an amphipathic helix to its C terminus. When mixed with lipid vesicles, FtsZ-mts was incorporated into the interior of some tubular vesicles. There it formed multiple Z rings that could move laterally in both directions along the length of the liposome and coalesce into brighter Z rings. Brighter Z rings produced visible constrictions in the liposome, suggesting that FtsZ itself can assemble the Z ring and generate a force. No other proteins were needed for assembly and force generation. PMID:18420899

Thermal conductivity engineering in width-modulated silicon nanowires and thermoelectric efficiency enhancement

NASA Astrophysics Data System (ADS)

Zianni, Xanthippi

2018-03-01

Width-modulated nanowires have been proposed as efficient thermoelectric materials. Here, the electron and phonon transport properties and the thermoelectric efficiency are discussed for dimensions above the quantum confinement regime. The thermal conductivity decreases dramatically in the presence of thin constrictions due to their ballistic thermal resistance. It shows a scaling behavior upon the width-modulation rate that allows for thermal conductivity engineering. The electron conductivity also decreases due to enhanced boundary scattering by the constrictions. The effect of boundary scattering is weaker for electrons than for phonons and the overall thermoelectric efficiency is enhanced. A ZT enhancement by a factor of 20-30 is predicted for width-modulated nanowires compared to bulk silicon. Our findings indicate that width-modulated nanostructures are promising for developing silicon nanostructures with high thermoelectric efficiency.

Optothermally actuated capillary burst valve

NASA Astrophysics Data System (ADS)

Eriksen, Johan; Bilenberg, Brian; Kristensen, Anders; Marie, Rodolphe

2017-04-01

We demonstrate the optothermal actuation of individual capillary burst valves in an all-polymer microfluidic device. The capillary burst valves are realised in a planar design by introducing a fluidic constriction in a microfluidic channel of constant depth. We show that a capillary burst valve can be burst by raising the temperature due to the temperature dependence of the fluid surface tension. We address individual valves by using a local heating platform based on a thin film of near infrared absorber dye embedded in the lid used to seal the microfluidic device [L. H. Thamdrup et al., Nano Lett. 10, 826-832 (2010)]. An individual valve is burst by focusing the laser in its vicinity. We demonstrate the capture of single polystyrene 7 μm beads in the constriction triggered by the bursting of the valve.

Paleopathological study of hallux valgus.

PubMed

Mays, S A

2005-02-01

Hallux valgus is the abnormal lateral deviation of the great toe. The principal cause is biomechanical, specifically the habitual use of footwear which constricts the toes. In this study, descriptions of the anatomical changes of hallux valgus from published cadaveric and clinical studies were used to generate criteria for identifying the condition in ancient skeletal remains. The value of systematic scoring of hallux valgus in paleopathology is illustrated using two British skeletal series, one dating from the earlier and one from the later Medieval period. It was found that hallux valgus was restricted to later Medieval burials. This appears consistent with archaeological and historical evidence for a rise in popularity, during the late Medieval period (at least among the richer social classes), of narrow, pointed shoes which would have constricted the toes. 2004 Wiley-Liss, Inc.

Severe Adult-onset Still Disease with Constrictive Pericarditis and Pleuritis That Was Successfully Treated with Tocilizumab in Addition to Corticosteroids and Cyclosporin A

PubMed Central

Kawaguchi, Hoshimi; Tsuboi, Hiroto; Yagishita, Mizuki; Terasaki, Toshihiko; Terasaki, Mayu; Shimizu, Masaru; Honda, Fumika; Ohyama, Ayako; Takahashi, Hiroyuki; Miki, Haruka; Yokosawa, Masahiro; Asashima, Hiromitsu; Hagiwara, Shinya; Kondo, Yuya; Matsumoto, Isao; Sumida, Takayuki

2017-01-01

Adult-onset Still disease (AOSD) is a systemic inflammatory disease characterized by fever, arthritis and rash. Corticosteroids represent a promising therapeutic option for AOSD; however, some resistant cases require immunosuppressants and biologic agents. We herein report the case of a 29-year-old Japanese man with severe AOSD, accompanied by constrictive pericarditis (CP) and pleuritis. Although 2 courses of steroid pulse and subsequent high-dose of prednisolone and cyclosporine A improved the patient's CP and pleuritis, his fever and inflammatory responses persisted. Tocilizumab (TCZ) was added to his treatment, which resulted in a rapid remission. This case suggests the usefulness of TCZ in the treatment of severe AOSD with CP and pleuritis. PMID:29269680

Tunable transport gap in narrow bilayer graphene nanoribbons

PubMed Central

Yu, Woo Jong; Duan, Xiangfeng

2013-01-01

The lack of a bandgap makes bulk graphene unsuitable for room temperature transistors with a sufficient on/off current ratio. Lateral constriction of charge carriers in graphene nanostructures or vertical inversion symmetry breaking in bilayer graphene are two potential strategies to mitigate this challenge, but each alone is insufficient to consistently achieve a large enough on/off ratio (e.g. > 1000) for typical logic applications. Herein we report the combination of lateral carrier constriction and vertical inversion symmetry breaking in bilayer graphene nanoribbons (GNRs) to tune their transport gaps and improve the on/off ratio. Our studies demonstrate that the on/off current ratio of bilayer GNRs can be systematically increased upon applying a vertical electric field, to achieve a largest on/off current ratio over 3000 at room temperature. PMID:23409239

Investigating the Slow Axonal Transport of Neurofilaments: A Precursor for Optimal Neuronal Signaling

NASA Astrophysics Data System (ADS)

Johnson, Christopher M.

Neurofilaments are the intermediate filaments of neurons and are the most abundant structure of the neuronal cytoskeleton. Once synthesized within the cell body they are then transported throughout the axon along microtubule tracks, driven by the molecular motors kinesin and dynein. This movement is characterized by long pauses with no movement interrupted by infrequent bouts of rapid movement, resulting in an aggregate dense cytoskeletal structure, which serves to regulate an axon's shape and size. Curiously, the modulated kinetics of these polymers produces a very regular, yet non-uniform, morphology in myelinated axons which are composed of discretely spaced myelin-ensheathed segments that are separated by short constricted regions called "nodes of Ranvier". This unique design optimizes the conduction velocity of myelinated axons at minimal fiber size. Hence, neurofilaments regulate the axon caliber to optimize neuron function. The goal of this dissertation is to investigate the motile mechanism of neurofilament transport as well as the resulting electrophysiological effects that follow. We start by examining highly time-resolved kymograph images generated from recorded neurofilament movement via epifluorescence microscopy. Using kymograph analysis, edge detection algorithms, and pixel smoothing tactics, neurofilament trajectories are extracted and used to obtain statistical distributions for the characteristics of how these filaments move within cells. The results suggest that the observed intermittent and bidirectional motions of these filaments might be explained by a model in which dynein and kinesin motors attach to a single neurofilament cargo and interact through mechanical forces only (i.e. a "tug-of-war" model). We test this hypothesis by developing two discrete-state stochastic models for the kinetic cycles of kinesin and dynein, which are then incorporated into a separate stochastic model that represents the posed tug-of-war scenario. We then systematically vary the number of motors in the model and attempt to identify those combinations of motors that show an agreement with the motility characteristic found from the above mentioned kymographs. By pruning the modeled data in accordance with the experimental results, our model can render an estimate of how many motors are attached to the cargo during transport. The model predicts that, on average, the total number of active motors on each neurofilament is relatively small and relatively independent of polymer length, which suggests that the motors may not be distributed uniformly along the filaments. Finally, we develop a model to explore the physiological function of axon morphology sculpted by neurofilament kinetics. Specifically, nodal constrictions are generated by slowing of neurofilaments in the internodal domain (Monsma et al., 2014), but the physiological function of these constrictions is unknown. To address this, we develop a computational model to investigate the effect of nodal constrictions on the axonal conduction velocity. For a fixed number of ion channels, we find that there is an optimal extent of nodal constriction which minimizes the internodal axon caliber that is required to achieve a given target conduction velocity, and we show that this is sensitive to the precise geometry of the axon and myelin sheath in the flanking paranodal regions. Thus axonal constrictions appear to be a biological adaptation that serves to minimize axonal volume, thereby maximizing the spatial and metabolic efficiency of these processes.

Leber Congenital Amaurosis

MedlinePlus

... Campaign to End Blindness Other Ways to Fight Blindness Corporate Support Volunteer Take Action You are here ... become narrow and constricted. A variety of pigmentary (color) changes can also occur in the retinal pigment ...

TRANSCRIPTIONAL UPREGULATION OF α2δ-1 ELEVATES ARTERIAL SMOOTH MUSCLE CELL CAV1.2 CHANNEL SURFACE EXPRESSION AND CEREBROVASCULAR CONSTRICTION IN GENETIC HYPERTENSION

PubMed Central

Bannister, John P.; Bulley, Simon; Narayanan, Damodaran; Thomas-Gatewood, Candice; Luzny, Patrik; Pachuau, Judith; Jaggar, Jonathan H.

2012-01-01

A hallmark of hypertension is an increase in arterial myocyte voltage-dependent Ca2+ (CaV1.2) currents that induces pathological vasoconstriction. CaV1.2 channels are heteromeric complexes comprising a pore forming CaV1.2α1 with auxiliary α2δ and β subunits. Molecular mechanisms that elevate CaV1.2 currents during hypertension and the potential contribution of CaV1.2 auxiliary subunits are unclear. Here, we investigated the pathological significance of α2δ subunits in vasoconstriction associated with hypertension. Age-dependent development of hypertension in spontaneously hypertensive rats (SHR) was associated with an unequal elevation in α2δ-1 and CaV1.2α1 mRNA and protein in cerebral artery myocytes, with α2δ-1 increasing more than CaV1.2α1. Other α2δ isoforms did not emerge in hypertension. Myocytes and arteries of hypertensive SHR displayed higher surface-localized α2δ-1 and CaV1.2α1 proteins, surface α2δ-1 to CaV1.2α1 ratio (α2δ-1:CaV1.2α1), CaV1.2 current-density and non-inactivating current, and pressure- and - depolarization-induced vasoconstriction than those of Wistar-Kyoto controls. Pregabalin, an α2δ-1 ligand, did not alter α2δ-1 or CaV1.2α1 total protein, but normalized α2δ-1 and CaV1.2α1 surface expression, surface α2δ-1:CaV1.2α1, CaV1.2 current-density and inactivation, and vasoconstriction in myocytes and arteries of hypertensive rats to control levels. Genetic hypertension is associated with an elevation in α2δ-1 expression that promotes surface trafficking of CaV1.2 channels in cerebral artery myocytes. This leads to an increase in CaV1.2 current-density and a reduction in current inactivation that induces vasoconstriction. Data also suggest that α2δ-1 targeting is a novel strategy that may be used to reverse pathological CaV1.2 channel trafficking to induce cerebrovascular dilation in hypertension. PMID:22949532

Transcriptional upregulation of α2δ-1 elevates arterial smooth muscle cell voltage-dependent Ca2+ channel surface expression and cerebrovascular constriction in genetic hypertension.

PubMed

Bannister, John P; Bulley, Simon; Narayanan, Damodaran; Thomas-Gatewood, Candice; Luzny, Patrik; Pachuau, Judith; Jaggar, Jonathan H

2012-10-01

A hallmark of hypertension is an increase in arterial myocyte voltage-dependent Ca2+ (CaV1.2) currents that induces pathological vasoconstriction. CaV1.2 channels are heteromeric complexes composed of a pore-forming CaV1.2α1 with auxiliary α2δ and β subunits. Molecular mechanisms that elevate CaV1.2 currents during hypertension and the potential contribution of CaV1.2 auxiliary subunits are unclear. Here, we investigated the pathological significance of α2δ subunits in vasoconstriction associated with hypertension. Age-dependent development of hypertension in spontaneously hypertensive rats was associated with an unequal elevation in α2δ-1 and CaV1.2α1 mRNA and protein in cerebral artery myocytes, with α2δ-1 increasing more than CaV1.2α1. Other α2δ isoforms did not emerge in hypertension. Myocytes and arteries of hypertensive spontaneously hypertensive rats displayed higher surface-localized α2δ-1 and CaV1.2α1 proteins, surface α2δ-1:CaV1.2α1 ratio, CaV1.2 current density and noninactivating current, and pressure- and depolarization-induced vasoconstriction than those of Wistar-Kyoto controls. Pregabalin, an α2δ-1 ligand, did not alter α2δ-1 or CaV1.2α1 total protein but normalized α2δ-1 and CaV1.2α1 surface expression, surface α2δ-1:CaV1.2α1, CaV1.2 current density and inactivation, and vasoconstriction in myocytes and arteries of hypertensive rats to control levels. Genetic hypertension is associated with an elevation in α2δ-1 expression that promotes surface trafficking of CaV1.2 channels in cerebral artery myocytes. This leads to an increase in CaV1.2 current-density and a reduction in current inactivation that induces vasoconstriction. Data also suggest that α2δ-1 targeting is a novel strategy that may be used to reverse pathological CaV1.2 channel trafficking to induce cerebrovascular dilation in hypertension.

7 CFR 51.1322 - Seriously misshapen.

Code of Federal Regulations, 2010 CFR

2010-01-01

... MARKETING ACT OF 1946 FRESH FRUITS, VEGETABLES AND OTHER PRODUCTS 1,2 (INSPECTION, CERTIFICATION, AND... misshapen means that the pear is excessively flattened or elongated for the variety, or is constricted or...

Modeling of the aorta artery aneurysms and renal artery stenosis using cardiovascular electronic system

PubMed Central

Hassani, Kamran; Navidbakhsh, Mahdi; Rostami, Mostafa

2007-01-01

Background The aortic aneurysm is a dilatation of the aortic wall which occurs in the saccular and fusiform types. The aortic aneurysms can rupture, if left untreated. The renal stenosis occurs when the flow of blood from the arteries leading to the kidneys is constricted by atherosclerotic plaque. This narrowing may lead to the renal failure. Previous works have shown that, modelling is a useful tool for understanding of cardiovascular system functioning and pathophysiology of the system. The present study is concerned with the modelling of aortic aneurysms and renal artery stenosis using the cardiovascular electronic system. Methods The geometrical models of the aortic aneurysms and renal artery stenosis, with different rates, were constructed based on the original anatomical data. The pressure drop of each section due to the aneurysms or stenosis was computed by means of computational fluid dynamics method. The compliance of each section with the aneurysms or stenosis is also calculated using the mathematical method. An electrical system representing the cardiovascular circulation was used to study the effects of these pressure drops and the compliance variations on this system. Results The results showed the decreasing of pressure along the aorta and renal arteries lengths, due to the aneurysms and stenosis, at the peak systole. The mathematical method demonstrated that compliances of the aorta sections and renal increased with the expansion rate of the aneurysms and stenosis. The results of the modelling, such as electrical pressure graphs, exhibited the features of the pathologies such as hypertension and were compared with the relevant experimental data. Conclusion We conclude from the study that the aortic aneurysms as well as renal artery stenosis may be the most important determinant of the arteries rupture and failure. Furthermore, these pathologies play important rules in increase of the cardiovascular pulse pressure which leads to the hypertension. PMID:17559685

Polarization-resolved SHG microscopy in cardiac hypertrophy study (Conference Presentation)

NASA Astrophysics Data System (ADS)

Wang, Zhonghai; Yuan, Cai; Shao, Yonghong; Bradshaw, Amy D.; Borg, Thomas K.; Gao, Bruce Z.

2017-02-01

Cardiac hypertrophy, a process initiated by mechanical alterations, is hypothesized to cause long-term molecular-level alteration in the sarcomere lattice, which is the main force-generating component in the heart muscle. This molecular-level alteration is beyond the resolving capacity of common light microscopy. Second harmonic generation (SHG) microscopy has unique capability for visualizing ordered molecular structures in biological tissues without labeling. Combined with polarization imaging technique, SHG microscopy is able to extract structural details of myosin at the molecular level so as to reveal molecular-level alterations that occur during hypertrophy. The myosin filaments are believed to possess C6 symmetry; thus, the nonlinear polarization response relationship between generated second harmonic light I^2ωand incident fundamental light I^ω is determined by nonlinear coefficients, χ_15, χ_31 and χ_33. χ_31/χ_15 is believed to be an indicator of the molecular symmetry of myosin filament, whileχ_33/χ_15represents the intramyosin orientation angle of the double helix. By changing the polarization of the incident light and evaluating the corresponding SHG signals, the molecular structure of the myosin, reflected by the χ coefficients, can be revealed. With this method, we studied the structural properties of heart tissues in different conditions, including those in normal, physiologically hypertrophic (heart tissue from postpartum female rats), and pathologically hypertrophic (heart tissue from transverse-aorta constricted rats) conditions. We found that ratios of χ_31/χ_15 showed no significant difference between heart tissues from different conditions; their values were all close to 1, which demonstrated that Kleinman symmetry held for all conditions. Ratios of χ_33/χ_15 from physiologically or pathologically hypertrophic heart tissues were raised and showed significant difference from those from normal heart tissues, which indicated that the intramyosin orientation angle of the double helix was altered when heart tissues hypertrophied. Polarization-resolved SHG microscopy permitted us to study heart tissues at the molecular level and may serve as a diagnostic tool for cardiac hypertrophy.

Stress-dependent dilated cardiomyopathy in mice with cardiomyocyte-restricted inactivation of cyclic GMP-dependent protein kinase I

PubMed Central

Frantz, Stefan; Klaiber, Michael; Baba, Hideo A.; Oberwinkler, Heike; Völker, Katharina; Gaβner, Birgit; Bayer, Barbara; Abeβer, Marco; Schuh, Kai; Feil, Robert; Hofmann, Franz; Kuhn, Michaela

2013-01-01

Aims Cardiac hypertrophy is a common and often lethal complication of arterial hypertension. Elevation of myocyte cyclic GMP levels by local actions of endogenous atrial natriuretic peptide (ANP) and C-type natriuretic peptide (CNP) or by pharmacological inhibition of phosphodiesterase-5 was shown to counter-regulate pathological hypertrophy. It was suggested that cGMP-dependent protein kinase I (cGKI) mediates this protective effect, although the role in vivo is under debate. Here, we investigated whether cGKI modulates myocyte growth and/or function in the intact organism. Methods and results To circumvent the systemic phenotype associated with germline ablation of cGKI, we inactivated the murine cGKI gene selectively in cardiomyocytes by Cre/loxP-mediated recombination. Mice with cardiomyocyte-restricted cGKI deletion exhibited unaltered cardiac morphology and function under resting conditions. Also, cardiac hypertrophic and contractile responses to β-adrenoreceptor stimulation by isoprenaline (at 40 mg/kg/day during 1 week) were unaltered. However, angiotensin II (Ang II, at 1000 ng/kg/min for 2 weeks) or transverse aortic constriction (for 3 weeks) provoked dilated cardiomyopathy with marked deterioration of cardiac function. This was accompanied by diminished expression of the [Ca2+]i-regulating proteins SERCA2a and phospholamban (PLB) and a reduction in PLB phosphorylation at Ser16, the specific target site for cGKI, resulting in altered myocyte Ca2+i homeostasis. In isolated adult myocytes, CNP, but not ANP, stimulated PLB phosphorylation, Ca2+i-handling, and contractility via cGKI. Conclusion These results indicate that the loss of cGKI in cardiac myocytes compromises the hypertrophic program to pathological stimulation, rendering the heart more susceptible to dysfunction. In particular, cGKI mediates stimulatory effects of CNP on myocyte Ca2+i handling and contractility. PMID:22199120

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 ...

Genetics Home Reference: Raynaud phenomenon

MedlinePlus

... the pads of the fingers or tissue death ( necrosis ) can occur. Primary Raynaud phenomenon often begins between ... are related to excessive narrowing (constriction) of small blood vessels in response to cold or stress. Variations in ...

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.

A groundwater convection model for Rio Grande rift geothermal resources

NASA Technical Reports Server (NTRS)

Morgan, P.; Harder, V.; Daggett, P. H.; Swanberg, C. A.

1981-01-01

It has been proposed that forced convection, driven by normal groundwater flow through the interconnected basins of the Rio Grande rift is the primary source mechanism for the numerous geothermal anomalies along the rift. A test of this concept using an analytical model indicates that significant forced convection must occur in the basins even if permeabilities are as low as 50-200 millidarcies at a depth of 2 km. Where groundwater flow is constricted at the discharge areas of the basins forced convection can locally increase the gradient to a level where free convection also occurs, generating surface heat flow anomalies 5-15 times background. A compilation of groundwater data for the rift basins shows a strong correlation between constrictions in groundwater flow and hot springs and geothermal anomalies, giving strong circumstantial support to the convection model.

Visual training improves underwater vision in children.

PubMed

Gislén, Anna; Warrant, Eric J; Dacke, Marie; Kröger, Ronald H H

2006-10-01

Children in a tribe of sea-gypsies from South-East Asia have been found to have superior underwater vision compared to European children. In this study, we show that the improved underwater vision of these Moken children is not due to better contrast sensitivity in general. We also show that European children can achieve the same underwater acuity as the Moken children. After 1 month of underwater training (11 sessions) followed by 4 months with no underwater activities, European children showed improved underwater vision and distinct bursts of pupil constriction. When tested 8 months after the last training session in an outdoor pool in bright sunlight-comparable to light environments in South-East Asia-the children had attained the same underwater acuity as the sea-gypsy children. The achieved performance can be explained by the combined effect of pupil constriction and strong accommodation.

Fabrication of hybrid molecular devices using multi-layer graphene break junctions.

PubMed

Island, J O; Holovchenko, A; Koole, M; Alkemade, P F A; Menelaou, M; Aliaga-Alcalde, N; Burzurí, E; van der Zant, H S J

2014-11-26

We report on the fabrication of hybrid molecular devices employing multi-layer graphene (MLG) flakes which are patterned with a constriction using a helium ion microscope or an oxygen plasma etch. The patterning step allows for the localization of a few-nanometer gap, created by electroburning, that can host single molecules or molecular ensembles. By controlling the width of the sculpted constriction, we regulate the critical power at which the electroburning process begins. We estimate the flake temperature given the critical power and find that at low powers it is possible to electroburn MLG with superconducting contacts in close proximity. Finally, we demonstrate the fabrication of hybrid devices with superconducting contacts and anthracene-functionalized copper curcuminoid molecules. This method is extendable to spintronic devices with ferromagnetic contacts and a first step towards molecular integrated circuits.

Fabrication of hybrid molecular devices using multi-layer graphene break junctions

NASA Astrophysics Data System (ADS)

Island, J. O.; Holovchenko, A.; Koole, M.; Alkemade, P. F. A.; Menelaou, M.; Aliaga-Alcalde, N.; Burzurí, E.; van der Zant, H. S. J.

2014-11-01

We report on the fabrication of hybrid molecular devices employing multi-layer graphene (MLG) flakes which are patterned with a constriction using a helium ion microscope or an oxygen plasma etch. The patterning step allows for the localization of a few-nanometer gap, created by electroburning, that can host single molecules or molecular ensembles. By controlling the width of the sculpted constriction, we regulate the critical power at which the electroburning process begins. We estimate the flake temperature given the critical power and find that at low powers it is possible to electroburn MLG with superconducting contacts in close proximity. Finally, we demonstrate the fabrication of hybrid devices with superconducting contacts and anthracene-functionalized copper curcuminoid molecules. This method is extendable to spintronic devices with ferromagnetic contacts and a first step towards molecular integrated circuits.

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.

Isolated cortical visual loss with subtle brain MRI abnormalities in a case of hypoxic-ischemic encephalopathy.

PubMed

Margolin, Edward; Gujar, Sachin K; Trobe, Jonathan D

2007-12-01

A 16-year-old boy who was briefly asystolic and hypotensive after a motor vehicle accident complained of abnormal vision after recovering consciousness. Visual acuity was normal, but visual fields were severely constricted without clear hemianopic features. The ophthalmic examination was otherwise normal. Brain MRI performed 11 days after the accident showed no pertinent abnormalities. At 6 months after the event, brain MRI demonstrated brain volume loss in the primary visual cortex and no other abnormalities. One year later, visual fields remained severely constricted; neurologic examination, including formal neuropsychometric testing, was normal. This case emphasizes the fact that hypoxic-ischemic encephalopathy (HIE) may cause enduring damage limited to primary visual cortex and that the MRI abnormalities may be subtle. These phenomena should be recognized in the management of patients with HIE.

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

Light-sensitive brain pathways and aging.

PubMed

Daneault, V; Dumont, M; Massé, É; Vandewalle, G; Carrier, J

2016-03-15

Notwithstanding its effects on the classical visual system allowing image formation, light acts upon several non-image-forming (NIF) functions including body temperature, hormonal secretions, sleep-wake cycle, alertness, and cognitive performance. Studies have shown that NIF functions are maximally sensitive to blue wavelengths (460-480 nm), in comparison to longer light wavelengths. Higher blue light sensitivity has been reported for melatonin suppression, pupillary constriction, vigilance, and performance improvement but also for modulation of cognitive brain functions. Studies investigating acute stimulating effects of light on brain activity during the execution of cognitive tasks have suggested that brain activations progress from subcortical regions involved in alertness, such as the thalamus, the hypothalamus, and the brainstem, before reaching cortical regions associated with the ongoing task. In the course of aging, lower blue light sensitivity of some NIF functions has been reported. Here, we first describe neural pathways underlying effects of light on NIF functions and we discuss eye and cerebral mechanisms associated with aging which may affect NIF light sensitivity. Thereafter, we report results of investigations on pupillary constriction and cognitive brain sensitivity to light in the course of aging. Whereas the impact of light on cognitive brain responses appears to decrease substantially, pupillary constriction seems to remain more intact over the lifespan. Altogether, these results demonstrate that aging research should take into account the diversity of the pathways underlying the effects of light on specific NIF functions which may explain their differences in light sensitivity.

Multimodal modeling and validation of simplified vocal tract acoustics for sibilant /s/

NASA Astrophysics Data System (ADS)

Yoshinaga, T.; Van Hirtum, A.; Wada, S.

2017-12-01

To investigate the acoustic characteristics of sibilant /s/, multimodal theory is applied to a simplified vocal tract geometry derived from a CT scan of a single speaker for whom the sound spectrum was gathered. The vocal tract was represented by a concatenation of waveguides with rectangular cross-sections and constant width, and a sound source was placed either at the inlet of the vocal tract or downstream from the constriction representing the sibilant groove. The modeled pressure amplitude was validated experimentally using an acoustic driver or airflow supply at the vocal tract inlet. Results showed that the spectrum predicted with the source at the inlet and including higher-order modes matched the spectrum measured with the acoustic driver at the inlet. Spectra modeled with the source downstream from the constriction captured the first characteristic peak observed for the speaker at 4 kHz. By positioning the source near the upper teeth wall, the higher frequency peak observed for the speaker at 8 kHz was predicted with the inclusion of higher-order modes. At the frequencies of the characteristic peaks, nodes and antinodes of the pressure amplitude were observed in the simplified vocal tract when the source was placed downstream from the constriction. These results indicate that the multimodal approach enables to capture the amplitude and frequency of the peaks in the spectrum as well as the nodes and antinodes of the pressure distribution due to /s/ inside the vocal tract.

UBF-binding site arrays form pseudo-NORs and sequester the RNA polymerase I transcription machinery

PubMed Central

Mais, Christine; Wright, Jane E.; Prieto, José-Luis; Raggett, Samantha L.; McStay, Brian

2005-01-01

Human ribosomal genes (rDNA) are located in nucleolar organizer regions (NORs) on the short arms of acrocentric chromosomes. Metaphase NORs that were transcriptionally active in the previous cell cycle appear as prominent chromosomal features termed secondary constrictions that are achromatic in chromosome banding and positive in silver staining. The architectural RNA polymerase I (pol I) transcription factor UBF binds extensively across rDNA throughout the cell cycle. To determine if UBF binding underpins NOR structure, we integrated large arrays of heterologous UBF-binding sequences at ectopic sites on human chromosomes. These arrays efficiently recruit UBF even to sites outside the nucleolus and, during metaphase, form novel silver stainable secondary constrictions, termed pseudo-NORs, morphologically similar to NORs. We demonstrate for the first time that in addition to UBF the other components of the pol I machinery are found associated with sequences across the entire human rDNA repeat. Remarkably, a significant fraction of these same pol I factors are sequestered by pseudo-NORs independent of both transcription and nucleoli. Because of the heterologous nature of the sequence employed, we infer that sequestration is mediated primarily by protein–protein interactions with UBF. These results suggest that extensive binding of UBF is responsible for formation and maintenance of the secondary constriction at active NORs. Furthermore, we propose that UBF mediates recruitment of the pol I machinery to nucleoli independently of promoter elements. PMID:15598984

Cyclooxygenase-2-dependent bronchoconstriction in perfused rat lungs exposed to endotoxin.

PubMed

Uhlig, S; Nüsing, R; von Bethmann, A; Featherstone, R L; Klein, T; Brasch, F; Müller, K M; Ullrich, V; Wendel, A

1996-05-01

Lipopolysaccharides (LPS), widely used to study the mechanisms of gram-negative sepsis, increase airway resistance by constriction of terminal bronchioles. The role of the cyclooxygenase (COX) isoenzymes and their prostanoid metabolites in this process was studied. Pulmonary resistance, the release of thromboxane (TX) and the expression of COX-2 mRNA were measured in isolated blood-free perfused rat lungs exposed to LPS. LPS induced the release of TX and caused increased airway resistance after about 30 min. Both TX formation and LPS-induced bronchoconstriction were prevented by treatment with the unspecific COX inhibitor acetyl salicylic acid, the specific COX-2 inhibitor CGP-28238, dexamethasone, actinomycin D, or cycloheximide. LPS-induced bronchoconstriction was also inhibited by the TX receptor antagonist BM-13177. The TX-mimetic compound, U-46619, increased airway resistance predominantly by constricting terminal bronchioles. COX-2-specific mRNA in lung tissue was elevated after LPS exposure, and this increase was attenuated by addition of dexamethasone or of actinomycin D. In contrast to LPS, platelet-activating factor (PAF) induced immediate TX release and bronchoconstriction that was prevented by acetyl salicylic acid, but not by CGP-28238. LPS elicits the following biochemical and functional changes in rat lungs: (i) induction of COX-2; (ii) formation of prostaglandins and TX; (iii) activation of the TX receptor on airway smooth muscle cells; (iv) constriction of terminal bronchioles; and (v) increased airway resistance. In contrast to LPS, the PAF-induced TX release is likely to depend on COX-1.

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.

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 endoplasmic reticulum (ER) and mitochondria associate at multiple contact sites to form specific domains known as mitochondria-ER associated membranes (MAMs) that play a role in the regulation of various cellular processes such as Ca2+ transfer, autophagy, and inflammation. Recently, it has been suggested that MAMs are also involved in mitochondrial dynamics, especially fission events. Cytological analysis showed that ER tubules were frequently located close to each other in mitochondrial fission sites that accumulate fission-related proteins. Three-dimensional (3D) imaging of ER-mitochondrial contacts in yeast mitochondria by using cryo-electron tomography also showed that ER tubules were attached near the constriction site, which is considered to be a fission site1). MAMs have been suggested to play a role in the initiation of mitochondrial fission, although the molecular relationships between MAMs and the mitochondrial fission process have not been established. Although an ER-mitochondrial membrane association has also been observed at the fission site in mammalian mitochondria, the detailed organization of MAMs around mammalian mitochondria remains to be established. To visualize the 3D distribution of the ER-mitochondrial contacts around the mitochondria, especially around the constriction site in mammalian cells, we attempted 3D structural analysis of the mammalian cytoplasm using high-resolution focused ion-beam scanning electron microscopy (FIB-SEM) tomography, and observed the distribution pattern of ER contacts around the mammalian mitochondrial constriction site.Rat hepatocytes and HeLa cells were used. Liver tissue was obtained from male rats (Wistar, 6W) fixed by transcardial perfusion of 2% paraformaldehyde and 2.5% glutaraldehyde in 0.1 M cacodylate buffer (pH 7.4) under deep anesthesia. HeLa cells were fixed with the same fixative. The specimens were then stained en bloc to enhance membrane contrast and embedded in epoxy resin2). The surface of 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 Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Neural systemic impairment from whole-body vibration.

PubMed

Yan, Ji-Geng; Zhang, Lin-ling; Agresti, Michael; LoGiudice, John; Sanger, James R; Matloub, Hani S; Havlik, Robert

2015-05-01

Insidious brain microinjury from motor vehicle-induced whole-body vibration (WBV) has not yet been investigated. For a long time we have believed that WBV would cause cumulative brain microinjury and impair cerebral function, which suggests an important risk factor for motor vehicle accidents and secondary cerebral vascular diseases. Fifty-six Sprague-Dawley rats were divided into seven groups (n = 8): 1) 2-week normal control group, 2) 2-week sham control group (restrained in the tube without vibration), 3) 2-week vibration group (exposed to whole-body vibration at 30 Hz and 0.5g acceleration for 4 hr/day, 5 days/week, for 2 weeks), 4) 4-week sham control group, 5) 4-week vibration group, 6) 8-week sham control group, and 7) 8-week vibration group. At the end point, all rats were evaluated in behavior, physiological, and brain histopathological studies. The cerebral injury from WBV is a cumulative process starting with vasospasm squeezing of the endothelial cells, followed by constriction of the cerebral arteries. After the 4-week vibration, brain neuron apoptosis started. After the 8-week vibration, vacuoles increased further in the brain arteries. Brain capillary walls thickened, mean neuron size was obviously reduced, neuron necrosis became prominent, and wide-ranging chronic cerebral edema was seen. These pathological findings are strongly correlated with neural functional impairments. © 2014 Wiley Periodicals, Inc.

Pathogenetic role of the deafness-related M34T mutation of Cx26

PubMed Central

Bicego, Massimiliano; Beltramello, Martina; Melchionda, Salvatore; Carella, Massimo; Piazza, Valeria; Zelante, Leopoldo; Bukauskas, Feliksas F.; Arslan, Edoardo; Cama, Elona; Pantano, Sergio; Bruzzone, Roberto; D’Andrea, Paola; Mammano, Fabio

2010-01-01

Mutations in the GJB2 gene, which encodes the gap junction protein connexin26 (Cx26), are the major cause of genetic non-syndromic hearing loss. The role of the allelic variant M34T in causing hereditary deafness remains controversial. By combining genetic, clinical, biochemical, electrophysiological and structural modeling studies, we have re-assessed the pathogenetic role of the M34T mutation. Genetic and audiological data indicate that the majority of heterozygous carriers and all five compound heterozygotes exhibited an impaired auditory function. Functional expression in transiently transfected HeLa cells showed that, although M34T was correctly synthesized and targeted to the plasma membrane, it inefficiently formed intercellular channels that displayed an abnormal electrical behavior and retained only 11% of the unitary conductance of the wild-type protein (HCx26wt). Moreover, M34T channels failed to support the intercellular diffusion of Lucifer Yellow and the spreading of mechanically induced intercellular Ca2+ waves. When co-expressed together with HCx26wt, M34T exerted dominant-negative effects on cell–cell coupling. Our findings are consistent with a structural model, predicting that the mutation leads to a constriction of the channel pore. These data support the view that M34T is a pathological variant of Cx26 associated with hearing impairment. PMID:16849369

Xanthine Oxidase Inhibition with Febuxostat Attenuates Systolic Overload-induced Left Ventricular Hypertrophy and Dysfunction in Mice

PubMed Central

Xu, Xin; Hu, Xinli; Lu, Zhongbing; Zhang, Ping; Zhao, Lin; Wessale, Jerry L.; Bache, Robert J.; Chen, Yingjie

2008-01-01

The purine analog xanthine oxidase (XO) inhibitors (XOIs), allopurinol and oxypurinol, have been reported to protect against heart failure secondary to myocardial infarction or rapid ventricular pacing. Since these agents might influence other aspects of purine metabolism that could influence their effect, this study examined the effect of the non-purine XOI, febuxostat, on pressure overload-induced left ventricular (LV) hypertrophy and dysfunction. Transverse aortic constriction (TAC) in mice caused LV hypertrophy and dysfunction as well as increased myocardial nitrotyrosine at 8 days. TAC also caused increased phosphorylated Akt (p-AktSer473), p42/44 extracellular signal-regulated kinase (p-ErkThr202/Tyr204) and mammalian target of rapamycin (mTOR) (p-mTORSer2488). XO inhibition with febuxostat (5mg/kg/day by gavage for 8 days) beginning ~60 minutes after TAC attenuated the TAC-induced LV hypertrophy and dysfunction. Febuxostat blunted the TAC-induced increases in nitrotyrosine (indicating reduced myocardial oxidative stress), p-ErkThr202/Tyr204 and p-mTORSer2488, with no effect on total Erk or total mTOR. Febuxostat had no effect on myocardial p-AktSer473 or total Akt. The results suggest that XO inhibition with febuxostat reduced oxidative stress in the pressure overloaded LV, thereby diminishing the activation of pathways that result in pathologic hypertrophy and contractile dysfunction. PMID:18995179

Erbin is a negative modulator of cardiac hypertrophy

PubMed Central

Rachmin, Inbal; Tshori, Sagi; Smith, Yoav; Oppenheim, Amit; Marchetto, Sylvie; Kay, Gillian; Foo, Roger S.-Y.; Dagan, Noa; Golomb, Eliahu; Gilon, Dan; Borg, Jean-Paul; Razin, Ehud

2014-01-01

ErbB2 interacting protein (Erbin) is a widely expressed protein and participates in inhibition of several intracellular signaling pathways. Its mRNA has been found to be present in relatively high levels in the heart. However, its physiological role in the heart has not been explored. In the present work, we elucidated the role of Erbin in cardiac hypertrophy. Cardiac hypertrophy was induced in mice either by isoproterenol administration or by aortic constriction. The level of Erbin was significantly decreased in both models. Erbin−/− mice rapidly develop decompensated cardiac hypertrophy, and following severe pressure overload all Erbin−/− mice died from heart failure. Down-regulation of Erbin expression was also observed in biopsies derived from human failing hearts. It is known that Erbin inhibits Ras-mediated activation of the extracellular signal-regulated kinase (ERK) by binding to Soc-2 suppressor of clear homolog (Shoc2). Our data clearly show that ERK phosphorylation is enhanced in the heart tissues of Erbin−/− mice. Furthermore, we clearly demonstrate here that Erbin associates with Shoc2 in both whole hearts and in cardiomyocytes, and that in the absence of Erbin, Raf is phosphorylated and binds Shoc2, resulting in ERK phosphorylation. In conclusion, Erbin is an inhibitor of pathological cardiac hypertrophy, and this inhibition is mediated, at least in part, by modulating ERK signaling. PMID:24711380

Hyperspectral imaging of endogenous fluorescent metabolic molecules to identify pain states in central nervous system tissue

NASA Astrophysics Data System (ADS)

Staikopoulos, Vasiliki; Gosnell, Martin E.; Anwer, Ayad G.; Mustafa, Sanam; Hutchinson, Mark R.; Goldys, Ewa M.

2016-12-01

Fluorescence-based bio-imaging methods have been extensively used to identify molecular changes occurring in biological samples in various pathological adaptations. Auto-fluorescence generated by endogenous fluorescent molecules within these samples can interfere with signal to background noise making positive antibody based fluorescent staining difficult to resolve. Hyperspectral imaging uses spectral and spatial imaging information for target detection and classification, and can be used to resolve changes in endogenous fluorescent molecules such as flavins, bound and free NADH and retinoids that are involved in cell metabolism. Hyperspectral auto-fluorescence imaging of spinal cord slices was used in this study to detect metabolic differences within pain processing regions of non-pain versus sciatic chronic constriction injury (CCI) animals, an established animal model of peripheral neuropathy. By using an endogenous source of contrast, subtle metabolic variations were detected between tissue samples, making it possible to distinguish between animals from non-injured and injured groups. Tissue maps of native fluorophores, flavins, bound and free NADH and retinoids unveiled subtle metabolic signatures and helped uncover significant tissue regions with compromised mitochondrial function. Taken together, our results demonstrate that hyperspectral imaging provides a new non-invasive method to investigate central changes of peripheral neuropathic injury and other neurodegenerative disease models, and paves the way for novel cellular characterisation in health, disease and during treatment, with proper account of intrinsic cellular heterogeneity.

Never in mitosis gene A related kinase-6 attenuates pressure overload-induced activation of the protein kinase B pathway and cardiac hypertrophy.

PubMed

Bian, Zhouyan; Liao, Haihan; Zhang, Yan; Wu, Qingqing; Zhou, Heng; Yang, Zheng; Fu, Jinrong; Wang, Teng; Yan, Ling; Shen, Difei; Li, Hongliang; Tang, Qizhu

2014-01-01

Cardiac hypertrophy appears to be a specialized form of cellular growth that involves the proliferation control and cell cycle regulation. NIMA (never in mitosis, gene A)-related kinase-6 (Nek6) is a cell cycle regulatory gene that could induce centriole duplication, and control cell proliferation and survival. However, the exact effect of Nek6 on cardiac hypertrophy has not yet been reported. In the present study, the loss- and gain-of-function experiments were performed in Nek6 gene-deficient (Nek6-/-) mice and Nek6 overexpressing H9c2 cells to clarify whether Nek6 which promotes the cell cycle also mediates cardiac hypertrophy. Cardiac hypertrophy was induced by transthoracic aorta constriction (TAC) and then evaluated by echocardiography, pathological and molecular analyses in vivo. We got novel findings that the absence of Nek6 promoted cardiac hypertrophy, fibrosis and cardiac dysfunction, which were accompanied by a significant activation of the protein kinase B (Akt) signaling in an experimental model of TAC. Consistent with this, the overexpression of Nek6 prevented hypertrophy in H9c2 cells induced by angiotonin II and inhibited Akt signaling in vitro. In conclusion, our results demonstrate that the cell cycle regulatory gene Nek6 is also a critical signaling molecule that helps prevent cardiac hypertrophy and inhibits the Akt signaling pathway.

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.

Shortening accommodated by extension-parallel folding of detachment faults during oblique rifting in the Gulf of California

NASA Astrophysics Data System (ADS)

Seiler, Christian; Fletcher, John

2013-04-01

Large-scale fault corrugations or megamullions are a common feature of detachment faults and form either as original fault grooves, displacement-gradient folds or constrictional folds parallel to the extension direction. In highly oblique extensional settings such as the Gulf of California, horizontal shortening perpendicular to the extension direction is an inherent part of the regional stress field and likely forms a key factor during the development of extension-parallel fault corrugations. However, the amount of horizontal shortening absorbed by megamullions is difficult to quantify, and constrictional folding is not normally thought to accommodate significant strike-slip deformation. The Las Cuevitas and Santa Rosa detachments are two low-angle normal fault systems exposed on the Gulf of California rifted margin in northeastern Baja California, Mexico. The two detachments accommodate between ~7-9km of SE-directed extension and represent the next significant set of faults in direction of transport from the rift breakaway fault. Fault kinematics are highly complex, but suggest integrated normal, oblique- and strike-slip faulting, with kinematics controlled by the orientation of faults with respect to the regional transtensional stress field. Both fault systems are strongly corrugated, with megamullion amplitudes of ~4-7km and half wavelenghts of between ~15 to 20km. Differential folding of the syntectonic basin-fill of the supradetachment basins strongly suggest that the observed megamullions formed largely, though not exclusively, due to constrictional folding associated with the transtensional stress regime of the plate boundary. This is consistent with basin-scale facies variations that record differential uplift and subsidence in antiformal and synformal megamullion domains, respectively. Compared to the two detachments, the San Pedro Martir fault - the master fault of the rift system at this latitude - shows more subtle fault corrugations with amplitudes of <3km. Unlike the Las Cuevitas and Santa Rosa detachments, though, there is no evidence for constrictional folding on the San Pedro Martir fault. Instead, the observed corrugations likely represent original grooves of the fault plane, formed as adjacent fault nuclei joined along-strike during fault growth. Comparison between the sinuosity of the San Pedro Martir fault (1.08), attributed entirely to original fault asperities, with the sinuosity of the two detachment systems (Las Cuevitas detachment: 1.17, Santa Rosa detachment: 1.22), suggests that about 10% of shortening occurred on each of the two detachments due to synextensional constrictional folding. This corresponds to a combined total of ~8km of N-S shortening, or ~10km of dextral shear resolved in direction of the relative plate motion, and occurs in addition to ~21km of right-lateral strain accommodated by clockwise vertical-axis block rotations. Thus, strain in this part of the rift system was partitioned between discrete extensional faulting on the two detachment systems, and significant right-lateral shear accommodated by distributed volume deformation.

Culvert roughness elements for native Utah fish passage : phase II.

DOT National Transportation Integrated Search

2012-04-01

Native fishes have become an increasingly important concern when designing fish passable culverts. Many operational culverts constrict waterways which increase velocities and prevent upstream passage of small fish species. The current method to ensur...

Wave-function description of conductance mapping for a quantum Hall electron interferometer

NASA Astrophysics Data System (ADS)

Kolasiński, K.; Szafran, B.

2014-04-01

Scanning gate microscopy of quantum point contacts (QPC) in the integer quantum Hall regime is considered in terms of the scattering wave functions with a finite-difference implementation of the quantum transmitting boundary approach. Conductance (G) maps for a clean QPC as well as for a system including an antidot within the QPC constriction are evaluated. The steplike locally flat G maps for clean QPCs turn into circular resonances that are reentrant in an external magnetic field when the antidot is introduced to the constriction. The current circulation around the antidot and the spacing of the resonances at the magnetic field scale react to the probe approaching the QPC. The calculated G maps with a rigid but soft antidot potential reproduce the features detected recently in the electron interferometer [F. Martins et al., Sci. Rep. 3, 1416 (2013), 10.1038/srep01416].

Doped ZrO2 for future lead free piezoelectric devices

NASA Astrophysics Data System (ADS)

Starschich, S.; Böttger, U.

2018-01-01

The ferroelectric and piezoelectric properties of doped ZrO2 prepared by chemical solution deposition (CSD) are investigated. Doping with different elements such as Mg, In, La, and Y leads to a stabilization of the constricted hysteresis. As shown in a previous work, for the constricted hysteresis of ZrO2, the piezoelectric response is significantly larger compared to ZrO2 with a normal hysteresis. The Mg doped ZrO2 shows a strong temperature and cycle stability. For the piezoelectric properties, a magnesium concentration of 7% shows the largest piezoelectric response with a piezoelectric coefficient of >10 pm/V, as well as the best cycle stability. Due to thicker films, which can be realized by the CSD technique, the shown doped ZrO2 films are a promising candidate for energy related applications such as piezoelectric energy harvesting as well as for microelectromechanical systems.

Long-term cardiovascular evaluation of patients with Hodgkin's disease treated by thoracic mantle radiation therapy

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

Applefeld, M.M.; Slawson, R.G.; Spicer, K.M.

1982-04-01

The long-term cardiac effects of anterior-weighted thoracic mantle field radiotherapy were assessed in 25 patients treated for Hodgkin's disease. These patients underwent an evaluation that included a careful history and physical examination, ECG, M-mode echocardiogram, exercise ECG-gated radionuclide ventriculography, and cardiac catheterization. In these 25 patients evaluated 37-144 months (median, 96) after completion of thoracic mantle radiotherapy, eight had constrictive pericarditis; eight had occult constrictive pericarditis; three had an abnormal response to fluid challenge; three had suspected or proven occlusive coronary artery disease; and one each had a cardiomyopathy and diminished functional capacity on exercise testing. Only one patient appearsmore » to be normal after evaluation. The clinical spectrum of delayed-appearing radiation-induced cardiac disease in patients treated by anterior-weighted thoracic mantle fields and our suggestions for its treatment are discussed.« less

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.

Notch-dependent epithelial fold determines boundary formation between developmental fields in the Drosophila antenna.

PubMed

Ku, Hui-Yu; Sun, Y Henry

2017-07-01

Compartment boundary formation plays an important role in development by separating adjacent developmental fields. Drosophila imaginal discs have proven valuable for studying the mechanisms of boundary formation. We studied the boundary separating the proximal A1 segment and the distal segments, defined respectively by Lim1 and Dll expression in the eye-antenna disc. Sharp segregation of the Lim1 and Dll expression domains precedes activation of Notch at the Dll/Lim1 interface. By repressing bantam miRNA and elevating the actin regulator Enable, Notch signaling then induces actomyosin-dependent apical constriction and epithelial fold. Disruption of Notch signaling or the actomyosin network reduces apical constriction and epithelial fold, so that Dll and Lim1 cells become intermingled. Our results demonstrate a new mechanism of boundary formation by actomyosin-dependent tissue folding, which provides a physical barrier to prevent mixing of cells from adjacent developmental fields.

Very low threshold-current temperature sensitivity in constricted double-heterojunction AlGaAs lasers

NASA Technical Reports Server (NTRS)

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

1981-01-01

The temperature dependence of threshold currents in constricted double-heterojunction diode lasers with strong lateral mode confinement is found to be significantly milder than for other types of lasers. The threshold-current relative variations with ambient temperature are typically two to three times less than for other devices of CW-operation capability. Over the interval 10-70 C the threshold currents fit the empirical exponential law exp/(T2-T1)/T0/ with T0 values in the 240-375 C range in pulsed operation, and in the 200-310 C range in CW operation. The external differential quantum efficiency and the mode far-field pattern near threshold are virtually invariant with temperature. The possible causes of high-T0 behavior are analyzed, and a new phenomenon - temperature-dependent current focusing - is presented to explain the results.

Using the Circumplex Model of Affect to Study Valence and Arousal Ratings of Emotional Faces by Children and Adults with Autism Spectrum Disorders

PubMed Central

Bansal, Ravi; Liu, Jun; Gerber, Andrew J.; Goh, Suzanne; Posner, Jonathan; Colibazzi, Tiziano; Algermissen, Molly; Chiang, I-Chin; Russell, James A.; Peterson, Bradley S.

2015-01-01

The Affective Circumplex Model holds that emotions can be described as linear combinations of two underlying, independent neurophysiological systems (arousal, valence). Given research suggesting individuals with autism spectrum disorders (ASD) have difficulty processing emotions, we used the circumplex model to compare how individuals with ASD and typically-developing (TD) individuals respond to facial emotions. Participants (51 ASD, 80 TD) rated facial expressions along arousal and valence dimensions; we fitted closed, smooth, 2-dimensional curves to their ratings to examine overall circumplex contours. We modeled individual and group influences on parameters describing curve contours to identify differences in dimensional effects across groups. Significant main effects of diagnosis indicated the ASD-group’ s ratings were constricted for the entire circumplex, suggesting range constriction across all emotions. Findings did not change when covarying for overall intelligence. PMID:24234677

Litomosoides silvai (Nematoda: Onchocercidae) parasitizing Akodon montensis (Rodentia: Cricetidae) in the southern region of Brazil.

PubMed

Gressler, Lucas Trevisan; Krawczak, Felipe da Silva; Knoff, Marcelo; Monteiro, Silvia Gonzalez; Labruna, Marcelo Bahia; Binder, Lina de Campos; Oliveira, Caroline Sobotyk de; Notarnicola, Juliana

2017-01-01

In the present study, Litomosoides silvai parasitizing Akodon montensis in the southern region of Brazil is reported for the first time. New morphological information is provided for some structures of this nematode species, such as a flattened cephalic extremity, presence of two dorsal cephalic papillae, female tail with a constriction at its tip, "s" shaped vagina, spicules characteristic of the carinii species group and microfilaria tail constricted at the tip. This nematode was found parasitizing the thoracic cavity with a prevalence of 10% (2/20), mean intensity of 4 (6/2), mean abundance of 0.4 (8/20) and range of infection of 2-6 specimens per host, in southern Brazil. This occurrence of L. silvai in A. montensis is a new geographical record for southern Brazil, in the Upper Paraná Atlantic Forest ecoregion of the northwestern region of Rio Grande do Sul, which is part of the Atlantic Forest biome.

Method and apparatus for the application of textile treatment compositions to textile materials

DOEpatents

Argyle, M.D.; Propp, W.A.

1998-01-20

A system is described for applying textile treatment compositions to textile materials. A conduit member is provided which includes a passageway having a first end, a second end, and a medial portion with a constricted (narrowed) region. The passageway may include at least one baffle having an opening there through. A yarn strand is then moved through the passageway. A textile treatment composition (a sizing agent or dye) dissolved in a carrier medium (a supercritical fluid or liquefied gas) is thereafter introduced into the constricted region, preferably at an acute angle relative to the passageway. The carrier medium expands inside the passageway which causes delivery of the treatment composition to the yarn. The treated yarn then passes through the baffle (if used) which facilitates drying of the yarn. During this process, a carrier gas can be introduced into the passageway to ensure the production of a smooth, dry product. 1 fig.

Ultrasonography in neuralgic amyotrophy: Sensitivity, spectrum of findings, and clinical correlations.

PubMed

ArÁnyi, Zsuzsanna; Csillik, Anita; DéVay, Katalin; Rosero, Maja; Barsi, PéTer; BÖhm, Josef; Schelle, Thomas

2017-12-01

The aim of this study was to assess the value of ultrasonography in neuralgic amyotrophy. Fifty-three patients with 70 affected nerves were examined with high-resolution ultrasound. The most commonly affected nerve was the anterior interosseous (23%). Ultrasonographic abnormalities in the affected nerves, rather than in the brachial plexus, were observed, with an overall sensitivity of 74%. Findings included the swelling of the nerve/fascicle with or without incomplete/complete constriction and rotational phenomena (nerve torsion and fascicular entwinement). A significant difference was found among the categories of ultrasonographic findings with respect to clinical outcome (P = 0.01). In nerves with complete constriction and rotational phenomena, reinnervation was absent or negligible, indicating surgery was warranted. Ultrasonography may be used as a diagnostic aid in neuralgic amyotrophy, which was hitherto a clinical and electrophysiological diagnosis, and may also help in identifying potential surgical candidates. Muscle Nerve 56: 1054-1062, 2017. © 2017 Wiley Periodicals, Inc.

Calculation of the exchange coupling constants of copper binuclear systems based on spin-flip constricted variational density functional theory.

PubMed

Zhekova, Hristina R; Seth, Michael; Ziegler, Tom

2011-11-14

We have recently developed a methodology for the calculation of exchange coupling constants J in weakly interacting polynuclear metal clusters. The method is based on unrestricted and restricted second order spin-flip constricted variational density functional theory (SF-CV(2)-DFT) and is here applied to eight binuclear copper systems. Comparison of the SF-CV(2)-DFT results with experiment and with results obtained from other DFT and wave function based methods has been made. Restricted SF-CV(2)-DFT with the BH&HLYP functional yields consistently J values in excellent agreement with experiment. The results acquired from this scheme are comparable in quality to those obtained by accurate multi-reference wave function methodologies such as difference dedicated configuration interaction and the complete active space with second-order perturbation theory. © 2011 American Institute of Physics

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.

[Expressions of neuropathic pain-related proteins in the spinal cord dorsal horn in rats with bilateral chronic constriction injury].

PubMed

Shen, Le; Li, Xu; Wang, Hai-tang; Yu, Xue-rong; Huang, Yu-guang

2013-12-01

To evaluate the pain-related behavioral changes in rats with bilateral chronic constriction injury(bCCI)and identify the expressions of neuropathic pain-related proteins. The bCCI models were established by ligating the sciatic nerves in female Sprague Dawley rats. Both mechanical hyperalgesia and cold hyperalgesia were evaluated through electronic von Frey and acetone method. Liquid chromatography-mass spectrometry/mass spectrometry was applied to characterize the differentially expressed proteins. Both mechanical withdrawal threshold and cold hyperalgesia threshold decreased significantly on the postoperative day 7 and 14, when compared with na ve or sham rats(P <0.05). Twenty five differentially expressed proteins associated with bilateral CCI were discovered, with eighteen of them were upregulated and seven of them downregulated. The bCCT rats have remarkably decreased mechanical and cold hyperalgesia thresholds. Twenty five neuropathic pain-related proteins are found in the spinal cord dorsal horn.

Automated Measurement of Facial Expression in Infant-Mother Interaction: A Pilot Study

PubMed Central

Messinger, Daniel S.; Mahoor, Mohammad H.; Chow, Sy-Miin; Cohn, Jeffrey F.

2009-01-01

Automated facial measurement using computer vision has the potential to objectively document continuous changes in behavior. To examine emotional expression and communication, we used automated measurements to quantify smile strength, eye constriction, and mouth opening in two six-month-old/mother dyads who each engaged in a face-to-face interaction. Automated measurements showed high associations with anatomically based manual coding (concurrent validity); measurements of smiling showed high associations with mean ratings of positive emotion made by naive observers (construct validity). For both infants and mothers, smile strength and eye constriction (the Duchenne marker) were correlated over time, creating a continuous index of smile intensity. Infant and mother smile activity exhibited changing (nonstationary) local patterns of association, suggesting the dyadic repair and dissolution of states of affective synchrony. The study provides insights into the potential and limitations of automated measurement of facial action. PMID:19885384

Method and apparatus for the application of textile treatment compositions to textile materials

DOEpatents

Argyle, Mark D.; Propp, William Alan

1998-01-01

A system for applying textile treatment compositions to textile materials. A conduit member is provided which includes a passageway having a first end, a second end, and a medial portion with a constricted (narrowed) region. The passageway may include at least one baffle having an opening therethrough. A yarn strand is then moved through the passageway. A textile treatment composition (a sizing agent or dye) dissolved in a carrier medium (a supercritical fluid or liquified gas) is thereafter introduced into the constricted region, preferably at an acute angle relative to the passageway. The carrier medium expands inside the passageway which causes delivery of the treatment composition to the yarn. The treated yarn then passes through the baffle (if used) which facilitates drying of the yarn. During this process, a carrier gas can be introduced into the passageway to ensure the production of a smooth, dry product.

Effects of gravitational stress, hypokinesia and hypodynamia on the structure of the vascular bed of the spleen

NASA Technical Reports Server (NTRS)

Nesterenko, N. T.

1980-01-01

The effects of two extreme factors, hypokinesia and hypodynamia, on spleen vascular beds were studied on 180 male and female albino rats. Vessels were studied by roentgenography, microroentgenography, clearing of sections and histology. Gravity stress yielded construction of all links of arterial bed and of order 5-7 veins. Large intraorganic vein diameters changed significantly but erratically. Hypokinesia in early phases produced pronounced spleen size reduction. Veins and arteries constricted along entire length. Later hypokinetic stages showed arteries still constricted; veins began to dilate from week 4 of hypokinesia. Sinuosity, uneven contours and varicose dilations of walls in large arteries and veins occurred. Abrupt changes in parenchyma, e.g., atrophy of folliculi, narrowing of lumen of central arteries from thickening of muscular wall. After exposure to hypokinesia followed by gravitational stress, pronounced lesions such as deformation of vascular wall, including rupture, in all vessels of the spleen vascular bed.

Scaling behavior of the thermal conductivity of width-modulated nanowires and nanofilms for heat transfer control at the nanoscale.

PubMed

Zianni, Xanthippi; Jean, Valentin; Termentzidis, Konstantinos; Lacroix, David

2014-11-21

We report on scaling behavior of the thermal conductivity of width-modulated nanowires and nanofilms that have been studied with the phonon Monte Carlo technique. It has been found that the reduction of the thermal conductivity scales with the nanostructure transmissivity, a property entirely determined by the modulation geometry, irrespectively of the material choice. Tuning of the thermal conductivity is possible by the nanostructure width-modulation without strict limitations for the modulation profile. In addition, a very significant constriction thermal resistance due to width-discontinuity has been identified, in analogy to the contact thermal resistance between two dissimilar materials. The constriction thermal resistance also scales with the modulated nanostructure transmissivity. Our conclusions are generic indicating that a wide range of materials can be used for the modulated nanostructures. Direct heat flow control can be provided by designing the nanostructure width-modulation.

Notch-dependent epithelial fold determines boundary formation between developmental fields in the Drosophila antenna

PubMed Central

2017-01-01

Compartment boundary formation plays an important role in development by separating adjacent developmental fields. Drosophila imaginal discs have proven valuable for studying the mechanisms of boundary formation. We studied the boundary separating the proximal A1 segment and the distal segments, defined respectively by Lim1 and Dll expression in the eye-antenna disc. Sharp segregation of the Lim1 and Dll expression domains precedes activation of Notch at the Dll/Lim1 interface. By repressing bantam miRNA and elevating the actin regulator Enable, Notch signaling then induces actomyosin-dependent apical constriction and epithelial fold. Disruption of Notch signaling or the actomyosin network reduces apical constriction and epithelial fold, so that Dll and Lim1 cells become intermingled. Our results demonstrate a new mechanism of boundary formation by actomyosin-dependent tissue folding, which provides a physical barrier to prevent mixing of cells from adjacent developmental fields. PMID:28708823

Experimental proof of faster-is-slower in systems of frictional particles flowing through constrictions.

PubMed

Pastor, José M; Garcimartín, Angel; Gago, Paula A; Peralta, Juan P; Martín-Gómez, César; Ferrer, Luis M; Maza, Diego; Parisi, Daniel R; Pugnaloni, Luis A; Zuriguel, Iker

2015-12-01

The "faster-is-slower" (FIS) effect was first predicted by computer simulations of the egress of pedestrians through a narrow exit [D. Helbing, I. J. Farkas, and T. Vicsek, Nature (London) 407, 487 (2000)]. FIS refers to the finding that, under certain conditions, an excess of the individuals' vigor in the attempt to exit causes a decrease in the flow rate. In general, this effect is identified by the appearance of a minimum when plotting the total evacuation time of a crowd as a function of the pedestrian desired velocity. Here, we experimentally show that the FIS effect indeed occurs in three different systems of discrete particles flowing through a constriction: (a) humans evacuating a room, (b) a herd of sheep entering a barn, and (c) grains flowing out a 2D hopper over a vibrated incline. This finding suggests that FIS is a universal phenomenon for active matter passing through a narrowing.

Transformation of the ordered internal structures during the acceleration of fast charged particles in a dense plasma focus

NASA Astrophysics Data System (ADS)

Kubes, P.; Paduch, M.; Cikhardt, J.; Cikhardtova, B.; Klir, D.; Kravarik, J.; Rezac, K.; Zielinska, E.; Sadowski, M. J.; Szymaszek, A.; Tomaszewski, K.; Zaloga, D.

2017-07-01

The paper concerns important differences in the evolution of plasma column structures during the production of fusion neutrons in the first and subsequent neutron pulses, as observed for plasma-focus discharges performed with the deuterium filling. The first neutron pulse, of a more isotropic distribution, is usually produced during the formation of the first big plasmoid. The next neutron pulses can be generated by the fast deuterons moving dominantly in the downstream direction, at the instants of a disruption of the pinch constriction, when other plasmoids are formed during the constriction evolution. In both cases, the fusion neutrons are produced by a beam-target mechanism, and the acceleration of fast electron- and deuteron-beams can be interpreted by transformation and decay of the magnetic field associated with a filamentary structure of the current flow in the plasmoid.

The history of barbed sutures.

PubMed

Ruff, Gregory L

2013-09-01

Ligatures have been used for millennia to close wounds. Sterilization and synthetic polymers that degrade in a commensurate fashion with wound healing have been the most significant improvements in these age-old devices. However, the constricting loop of a traditional suture and subsequent ischemia ("approximate, don't strangulate") still account for the most common cause of wound dehiscence-necrosis. Inspired by the quill of the North American porcupine, I envisioned a bidirectional array of barbs that could secure tissue without relying on constricting loops. One set of barbs could anchor the other. In this article, I document the development process of these barbed sutures from concept to patent to manufacture and US Food and Drug Administration approval. Knotless, strong, and easy to place, barbed sutures could foreseeably supplant conventional sutures, particularly as endoscopic procedures become more common. They also offer the intriguing potential to suspend ptotic tissues without surgical intervention.

New development of cardiac tamponade on underlying effusive–constrictive pericarditis: an uncommon initial presentation of scleroderma

PubMed Central

Subramanian, Stalin R; Akram, Rakhshanda; Velayati, Arash; Chadow, Hal

2013-01-01

A 40-year-old man with a medical history of hypertension was admitted for weight loss, generalised weakness, joint pains and mottling of fingertips. The initial laboratory data revealed microangiopathic haemolytic anaemia, thrombocytopenia and acute renal failure. Intravenous steroids were started for possible diagnosis of systemic lupus erythematosus based on admission assessment. Intravenous immunoglobulin and plasmapharesis were subsequently added to the treatment plan to cover thrombotic thrombocytopenic purpura while his autoimmune panel was pending. The echocardiogram study on day 2 revealed cardiac tamponade for which he underwent pericardiocentesis and right heart catheterisation. The atrial waveforms postpericardiocentesis demonstrated effusive–constrictive pericarditis. His clinical condition kept on deteriorating with reaccumulation of pericardial effusion and further complicated by hemoperitoneum and colonic obstruction. He had cardiorespiratory arrest on his fourth admission day and was not revived. Anti-Scl-70 antibody came back positive. Autopsy findings confirmed the presence of fibrinous pericarditis and hemoperitoneum. PMID:23853085

Recurrent Pericarditis.

PubMed

Imazio, Massimo; Gribaudo, Elena; Gaita, Fiorenzo

Recurrent pericarditis is the most common and troublesome complication of pericarditis affecting 20% to 50% of patients. Its pathogenesis is often presumed to be immune-mediated, but additional investigations are needed to clarify the pathogenesis in order to develop etiology-oriented therapies. Imaging with computed tomography and especially cardiac magnetic resonance holds promise to help in the identification of more difficult cases and improve their management. Refractory recurrent pericarditis with corticosteroid dependence and colchicine resistance remain still an unsolved issue in search of new therapies, although old drugs such as azathioprine, intravenous immunoglobulins, and biological agents seem promising, but new randomized clinical trials are needed to confirm their role. Despite compromising the quality of life, idiopathic recurrent pericarditis has an overall good long-term outcome without mortality and significant risk of constrictive pericarditis evolution. The risk of constriction, the most feared complication, is related to the etiology and not the number of recurrences. Copyright © 2016 Elsevier Inc. All rights reserved.

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.

Wave reflection effects in the central circulation of American alligators (Alligator mississippiensis): what the heart sees.

PubMed

Syme, Douglas A; Gamperl, A Kurt; Braun, Marvin H; Jones, David R

2006-10-01

A large central compliance is thought to dominate the hemodynamics of all vertebrates except birds and mammals. Yet large crocodilians may adumbrate the avian and mammalian condition and set the stage for significant wave transmission (reflection) effects, with potentially detrimental impacts on cardiac performance. To investigate whether crocodilians exhibit wave reflection effects, pressures and flows were recorded from the right aorta, carotid artery, and femoral artery of six adult, anesthetized American alligators (Alligator mississippiensis) during control conditions and after experimentally induced vasodilation and constriction. Hallmarks of wave reflection phenomena were observed, including marked differences between the measured profiles for flow and pressure, peaking of the femoral pressure pulse, and a diastolic wave in the right aortic pressure profile. Pulse wave velocity and peripheral input impedance increased with progressive constriction, and thus changes in both the timing and magnitude of reflections accounted for the altered reflection effects. Resolution of pressure and flow waves into incident and reflected components showed substantial reflection effects within the right aorta, with reflection coefficients at the first harmonic approaching 0.3 when constricted. Material properties measured from isolated segments of blood vessels revealed a major reflection site at the periphery and, surprisingly, at the junction of the truncus and right aorta. Thus, while our results clearly show that significant wave reflection phenomena are not restricted to birds and mammals, they also suggest that rather than cope with potential negative impacts of reflections, the crocodilian heart simply avoids them because of a large impedance mismatch at the truncus.

Clinical efficacy of electronic apex locators: systematic review.

PubMed

Martins, Jorge N R; Marques, Duarte; Mata, António; Caramês, João

2014-06-01

Apical constriction has been proposed as the most appropriate apical limit for the endodontic working length. Despite being the most used, some limitations are attributed to the radiographic method of working length determination. It lacks precision because it is based on the average position of the apical constriction. The electronic apex locators have been presented as an alternative to the odontometry performed by radiography. These devices detect the transition of the pulp to the periodontal tissue, which is anatomically very close to the apical constriction and may perform with improved accuracy. A systematic review was performed to compare the radiographic and electronic methods. Clinical studies that compared both methods were searched for on 7 electronic databases, a manual search was performed on the bibliography of articles collected on the electronic databases, and the authors were contacted to ask for references of more research not detected on the electronic and manual search. Twenty-one articles were selected. The majority were comparative or evaluation studies, and very few clinical studies comparing both methods are available. Several methodological limitations are present on the collected articles and debated in this review. Although the available scientific evidence base is short and at considerable risk of bias, it is still possible to conclude that the apical locator reduces the patient radiation exposure and also that the electronic method may perform better on the working length determination. At least one radiographic control should be performed to detect possible errors of the electronic devices. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Choline Diet and Its Gut Microbe-Derived Metabolite, Trimethylamine N-Oxide, Exacerbate Pressure Overload-Induced Heart Failure.

PubMed

Organ, Chelsea L; Otsuka, Hiroyuki; Bhushan, Shashi; Wang, Zeneng; Bradley, Jessica; Trivedi, Rishi; Polhemus, David J; Tang, W H Wilson; Wu, Yuping; Hazen, Stanley L; Lefer, David J

2016-01-01

Trimethylamine N-oxide (TMAO), a gut microbe-dependent metabolite of dietary choline and other trimethylamine-containing nutrients, is both elevated in the circulation of patients having heart failure and heralds worse overall prognosis. In animal studies, dietary choline or TMAO significantly accelerates atherosclerotic lesion development in ApoE-deficient mice, and reduction in TMAO levels inhibits atherosclerosis development in the low-density lipoprotein receptor knockout mouse. C57BL6/J mice were fed either a control diet, a diet containing choline (1.2%) or a diet containing TMAO (0.12%) starting 3 weeks before surgical transverse aortic constriction. Mice were studied for 12 weeks after transverse aortic constriction. Cardiac function and left ventricular structure were monitored at 3-week intervals using echocardiography. Twelve weeks post transverse aortic constriction, myocardial tissues were collected to evaluate cardiac and vascular fibrosis, and blood samples were evaluated for cardiac brain natriuretic peptide, choline, and TMAO levels. Pulmonary edema, cardiac enlargement, and left ventricular ejection fraction were significantly (P<0.05, each) worse in mice fed either TMAO- or choline-supplemented diets when compared with the control diet. In addition, myocardial fibrosis was also significantly greater (P<0.01, each) in the TMAO and choline groups relative to controls. Heart failure severity is significantly enhanced in mice fed diets supplemented with either choline or the gut microbe-dependent metabolite TMAO. The present results suggest that additional studies are warranted examining whether gut microbiota and the dietary choline → TMAO pathway contribute to increased heart failure susceptibility. © 2015 American Heart Association, Inc.

Subangstrom Measurements of Enzyme Function Using a Biological Nanopore, SPRNT.

PubMed

Laszlo, A H; Derrrington, I M; Gundlach, J H

2017-01-01

Nanopores are emerging as new single-molecule tools in the study of enzymes. Based on the progress in nanopore sequencing of DNA, a tool called Single-molecule Picometer Resolution Nanopore Tweezers (SPRNT) was developed to measure the movement of enzymes along DNA in real time. In this new method, an enzyme is loaded onto a DNA (or RNA) molecule. A single-stranded DNA end of this complex is drawn into a nanopore by an electrostatic potential that is applied across the pore. The single-stranded DNA passes through the pore's constriction until the enzyme comes into contact with the pore. Further progression of the DNA through the pore is then controlled by the enzyme. An ion current that flows through the pore's constriction is modulated by the DNA in the constriction. Analysis of ion current changes reveals the advance of the DNA with high spatiotemporal precision, thereby providing a real-time record of the enzyme's activity. Using an engineered version of the protein nanopore MspA, SPRNT has spatial resolution as small as 40pm at millisecond timescales, while simultaneously providing the DNA's sequence within the enzyme. In this chapter, SPRNT is introduced and its extraordinary potential is exemplified using the helicase Hel308. Two distinct substates are observed for each one-nucleotide advance; one of these about half-nucleotide long steps is ATP dependent and the other is ATP independent. The spatiotemporal resolution of this low-cost single-molecule technique lifts the study of enzymes to a new level of precision, enabling exploration of hitherto unobservable enzyme dynamics in real time. © 2017 Elsevier Inc. All rights reserved.

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.

Bacopa monnieri: An evaluation of antihyperglycemic and antinociceptive potential of methanolic extract of whole plants.

PubMed

Taznin, Inin; Mukti, Mohsina; Rahmatullah, Mohammed

2015-11-01

Antihyperglycemic and antinociceptive activity studies were carried out with methanolic extract of whole plants of Bacopa monnieri, respectively, through oral glucose tolerance test and gastric pain model induced by acetic acid in Swiss albino mice. In OGTT (oral glucose tolerance tests) conducted with glucose-challenged mice, the extract, administered at four doses of 50, 100, 200 and 400mg per kg body weight, dose-dependently and significantly inhibited the increase in serum glucose concentrations, respectively, by 33.3, 34.2, 42.1 and 44.2%. A standard antihyperglycemic drug, glibenclamide, when administered at a dose of 10mg per kg body weight, inhibited increase in serum glucose concentration by 50.7%. From the results, it can be concluded that the methanolic extract of the plant possess significant antihyperglycemic potential. In antinociceptive activity tests, administration of the extract at the aforementioned four doses also significantly and dose-dependently reduced the number of acetic acid-induced gastric constrictions in mice. The percent inhibitions in gastric constrictions were, respectively, 43.4, 46.6, 50.0, and 53.4 at the above four doses. A reference antinociceptive drug, aspirin, when administered at a dose of 200 mg per kg body weight, reduced the number of gastric constrictions by 40.0%. Thus the extract at even the lowest dose of 50 mg, demonstrated antinociceptive activity better than that of aspirin, and which activity was much more than aspirin at the other three higher doses tested. The results demonstrate that the plant can be an excellent candidate for further studies towards isolation of antihyperglycemic and pain-killing compounds.

Variation in motor output and motor performance in a centrally generated motor pattern

PubMed Central

Norris, Brian J.; Doloc-Mihu, Anca; Calabrese, Ronald L.

2014-01-01

Central pattern generators (CPGs) produce motor patterns that ultimately drive motor outputs. We studied how functional motor performance is achieved, specifically, whether the variation seen in motor patterns is reflected in motor performance and whether fictive motor patterns differ from those in vivo. We used the leech heartbeat system in which a bilaterally symmetrical CPG coordinates segmental heart motor neurons and two segmented heart tubes into two mutually exclusive coordination modes: rear-to-front peristaltic on one side and nearly synchronous on the other, with regular side-to-side switches. We assessed individual variability of the motor pattern and the beat pattern in vivo. To quantify the beat pattern we imaged intact adults. To quantify the phase relations between motor neurons and heart constrictions we recorded extracellularly from two heart motor neurons and movement from the corresponding heart segments in minimally dissected leeches. Variation in the motor pattern was reflected in motor performance only in the peristaltic mode, where larger intersegmental phase differences in the motor neurons resulted in larger phase differences between heart constrictions. Fictive motor patterns differed from those in vivo only in the synchronous mode, where intersegmental phase differences in vivo had a larger front-to-rear bias and were more constrained. Additionally, load-influenced constriction timing might explain the amplification of the phase differences between heart segments in the peristaltic mode and the higher variability in motor output due to body shape assumed in this soft-bodied animal. The motor pattern determines the beat pattern, peristaltic or synchronous, but heart mechanics influence the phase relations achieved. PMID:24717348

The effect of channel shape, bed morphology, and shipwrecks on flow velocities in the Upper St. Clair River

USGS Publications Warehouse

Czuba, Jonathan A.; Oberg, Kevin; Best, Jim; Parsons, Daniel R.

2009-01-01

In the Great Lakes of North America, the St. Clair River is the major outlet of Lake Huron and conveys water to Lake St. Clair which then flows to Lake Erie. One major topic of interest is morphological change in the St. Clair River and its impact on water levels in the Upper Great Lakes and connecting channel flows. A combined multibeam echosounder (MBES) bathymetric survey and acoustic Doppler current profiler (ADCP) flow survey of the outlet of Lake Huron and the Upper St. Clair River was conducted July 21 – 25, 2008. This paper presents how channel morphology and shipwrecks affect the flow in the Upper St. Clair River. The river is most constricted at the Blue Water Bridge near Port Huron, Michigan, with water velocities over 2 ms-1 for a flow of 5,200 m3s-1. Downstream of this constriction, the river flows around a bend and expands creating a large recirculation zone along the left bank due to flow separation. This recirculation zone reduces the effective channel width, and thus increases flow velocities to over 2 ms-1 in this region. The surveys reveal several shipwrecks on the bed of the St. Clair River, which possess distinct wakes in their flow velocity downstream of the wrecks. The constriction and expansion of the channel, combined with forcing of the flow by bed topography, initiates channel-scale secondary flow, creating streamwise vortices that maintain coherence downstream over a distance of several channel widths.

Variations in Alveolar Partial Pressure for Carbon Dioxide and Oxygen Have Additive Not Synergistic Acute Effects on Human Pulmonary Vasoconstriction

PubMed Central

Croft, Quentin P. P.; Formenti, Federico; Talbot, Nick P.; Lunn, Daniel; Robbins, Peter A.; Dorrington, Keith L.

2013-01-01

The human pulmonary vasculature constricts in response to hypercapnia and hypoxia, with important consequences for homeostasis and adaptation. One function of these responses is to direct blood flow away from poorly-ventilated regions of the lung. In humans it is not known whether the stimuli of hypercapnia and hypoxia constrict the pulmonary blood vessels independently of each other or whether they act synergistically, such that the combination of hypercapnia and hypoxia is more effective than the sum of the responses to each stimulus on its own. We independently controlled the alveolar partial pressures of carbon dioxide (Paco 2) and oxygen (Pao 2) to examine their possible interaction on human pulmonary vasoconstriction. Nine volunteers each experienced sixteen possible combinations of four levels of Paco 2 (+6, +1, −4 and −9 mmHg, relative to baseline) with four levels of Pao 2 (175, 100, 75 and 50 mmHg). During each of these sixteen protocols Doppler echocardiography was used to evaluate cardiac output and systolic tricuspid pressure gradient, an index of pulmonary vasoconstriction. The degree of constriction varied linearly with both Paco 2 and the calculated haemoglobin oxygen desaturation (1-So 2). Mixed effects modelling delivered coefficients defining the interdependence of cardiac output, systolic tricuspid pressure gradient, ventilation, Paco 2 and So 2. No interaction was observed in the effects on pulmonary vasoconstriction of carbon dioxide and oxygen (p>0.64). Direct effects of the alveolar gases on systolic tricuspid pressure gradient greatly exceeded indirect effects arising from concurrent changes in cardiac output. PMID:23935847

Variations in alveolar partial pressure for carbon dioxide and oxygen have additive not synergistic acute effects on human pulmonary vasoconstriction.

PubMed

Croft, Quentin P P; Formenti, Federico; Talbot, Nick P; Lunn, Daniel; Robbins, Peter A; Dorrington, Keith L

2013-01-01

The human pulmonary vasculature constricts in response to hypercapnia and hypoxia, with important consequences for homeostasis and adaptation. One function of these responses is to direct blood flow away from poorly-ventilated regions of the lung. In humans it is not known whether the stimuli of hypercapnia and hypoxia constrict the pulmonary blood vessels independently of each other or whether they act synergistically, such that the combination of hypercapnia and hypoxia is more effective than the sum of the responses to each stimulus on its own. We independently controlled the alveolar partial pressures of carbon dioxide (Paco 2) and oxygen (Pao 2) to examine their possible interaction on human pulmonary vasoconstriction. Nine volunteers each experienced sixteen possible combinations of four levels of Paco 2 (+6, +1, -4 and -9 mmHg, relative to baseline) with four levels of Pao 2 (175, 100, 75 and 50 mmHg). During each of these sixteen protocols Doppler echocardiography was used to evaluate cardiac output and systolic tricuspid pressure gradient, an index of pulmonary vasoconstriction. The degree of constriction varied linearly with both Paco 2 and the calculated haemoglobin oxygen desaturation (1-So2). Mixed effects modelling delivered coefficients defining the interdependence of cardiac output, systolic tricuspid pressure gradient, ventilation, Paco 2 and So2. No interaction was observed in the effects on pulmonary vasoconstriction of carbon dioxide and oxygen (p>0.64). Direct effects of the alveolar gases on systolic tricuspid pressure gradient greatly exceeded indirect effects arising from concurrent changes in cardiac output.

Simulation of 'stationary' SAP and SEP phenomena by 2-dimensional potential field modelling.

PubMed

Cunningham, K; Halliday, A M; Jones, S J

1986-11-01

In order to model the distribution of potentials in the hand due to antidromic SAP propagation and in the body due to afferent conduction of the median nerve volley, 2-dimensional matrices of the appropriate shape were constructed, each containing a 'generator' consisting of up to 3 'source' and 3 'sink' points. The value of the field potential at other sites was calculated using a finite difference method. It was shown that the potential gradient is virtually zero in matrix zones which are separated from the region containing the generator by a constriction in the boundary of the conductor. Points on the far side of the constriction remain virtually equipotential, at a level determined by the potential at the junction. This is naturally influenced by the proximity of the generator, so that as the generator approaches the constriction a potential difference will develop between points on the far side, irrespective of their distance from the junction, and other remote parts of the matrix. In the context of human SAPs and SEPs, such factors may be of paramount importance in the generation of so-called 'stationary' or 'far-field' potentials. With additional postulates concerning the manner in which the SAP is attenuated by the termination of axons as it propagates through the hand, and the course taken by the median nerve volley between the arm and neck, it was possible to model the majority of stationary SAP phenomena described by Kimura et al. (1984), and also the distribution and latency of the P9 SEP component following median nerve stimulation.

Sustained conduction of vasomotor responses in rat mesenteric arteries in a two-compartment in vitro setup.

PubMed

Palao, Teresa; van Weert, Angela; de Leeuw, Anne; de Vos, Judith; Bakker, Erik N T P; van Bavel, Ed

2018-05-21

Conduction of vasomotor responses may contribute to long-term regulation of resistance artery function and structure. Most previous studies have addressed conduction of vasoactivity only during very brief stimulations. We developed a novel setup that allows the local pharmacological stimulation of arteries in vitro for extended periods of time, and studied the conduction of vasomotor responses in rat mesenteric arteries under those conditions. The new in vitro set up was based on the pressure myograph. The superfusion chamber was divided halfway along the vessel into two compartments, allowing an independent superfusion of the arterial segment in each compartment. Local and remote cumulative concentration-response curves were obtained for a range of vasoactive agents. Additional experiments were performed with the gap junction inhibitor 18β-glycyrrhetinic acid and in absence of the endothelium. Phenylephrine-induced constriction and acetylcholine-induced dilation were conducted over a measured distance up to 2.84 mm, and this conduction was maintained for 5 minutes. Conduction of acetylcholine-induced dilation was inhibited by 18β-glycyrrhetinic acid and conduction of phenylephrine-induced constriction was abolished in absence of the endothelium. Constriction in response to high K + was not conducted. Absence of remote stimulation dampened the local response to phenylephrine. This study demonstrates maintained conduction of vasoactive responses to physiological agonists in rat mesenteric small arteries likely via gap junctions and endothelial cells, providing a possible mechanism for the sustained functional and structural control of arterial networks. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Blood flow patterns underlie developmental heart defects

PubMed Central

Midgett, Madeline; Thornburg, Kent

2017-01-01

Although cardiac malformations at birth are typically associated with genetic anomalies, blood flow dynamics also play a crucial role in heart formation. However, the relationship between blood flow patterns in the early embryo and later cardiovascular malformation has not been determined. We used the chicken embryo model to quantify the extent to which anomalous blood flow patterns predict cardiac defects that resemble those in humans and found that restricting either the inflow to the heart or the outflow led to reproducible abnormalities with a dose-response type relationship between blood flow stimuli and the expression of cardiac phenotypes. Constricting the outflow tract by 10–35% led predominantly to ventricular septal defects, whereas constricting by 35–60% most often led to double outlet right ventricle. Ligation of the vitelline vein caused mostly pharyngeal arch artery malformations. We show that both cardiac inflow reduction and graded outflow constriction strongly influence the development of specific and persistent abnormal cardiac structure and function. Moreover, the hemodynamic-associated cardiac defects recapitulate those caused by genetic disorders. Thus our data demonstrate the importance of investigating embryonic blood flow conditions to understand the root causes of congenital heart disease as a prerequisite to future prevention and treatment. NEW & NOTEWORTHY Congenital heart defects result from genetic anomalies, teratogen exposure, and altered blood flow during embryonic development. We show here a novel “dose-response” type relationship between the level of blood flow alteration and manifestation of specific cardiac phenotypes. We speculate that abnormal blood flow may frequently underlie congenital heart defects. PMID:28062416

Effects of depth and chest volume on cardiac function during breath-hold diving.

PubMed

Marabotti, Claudio; Scalzini, Alessandro; Cialoni, Danilo; Passera, Mirko; Ripoli, Andrea; L'Abbate, Antonio; Bedini, Remo

2009-07-01

Cardiac response to breath-hold diving in human beings is primarily characterized by the reduction of both heart rate and stroke volume. By underwater Doppler-echocardiography we observed a "restrictive/constrictive" left ventricular filling pattern compatible with the idea of chest squeeze and heart compression during diving. We hypothesized that underwater re-expansion of the chest would release heart constriction and normalize cardiac function. To this aim, 10 healthy male subjects (age 34.2 +/- 10.4) were evaluated by Doppler-echocardiography during breath-hold immersion at a depth of 10 m, before and after a single maximal inspiration from a SCUBA device. During the same session, all subjects were also studied at surface (full-body immersion) and at 5-m depth in order to better characterize the relationship of echo-Doppler pattern with depth. In comparison to surface immersion, 5-m deep diving was sufficient to reduce cardiac output (P = 0.042) and increase transmitral E-peak velocity (P < 0.001). These changes remained unaltered at a 10-m depth. Chest expansion at 10 m decreased left ventricular end-systolic volume (P = 0.024) and increased left ventricular stroke volume (P = 0.024). In addition, it decreased transmitral E-peak velocity (P = 0.012) and increased deceleration time of E-peak (P = 0.021). In conclusion the diving response, already evident during shallow diving (5 m) did not progress during deeper dives (10 m). The rapid improvement in systolic and diastolic function observed after lung volume expansion is congruous with the idea of a constrictive effect on the heart exerted by chest squeeze.

Pupillary Responses to Full-Field Chromatic Stimuli Are Reduced in Patients with Early-Stage Primary Open-Angle Glaucoma.

PubMed

Najjar, Raymond P; Sharma, Sourabh; Atalay, Eray; Rukmini, Annadata V; Sun, Christopher; Lock, Jing Zhan; Baskaran, Mani; Perera, Shamira A; Husain, Rahat; Lamoureux, Ecosse; Gooley, Joshua J; Aung, Tin; Milea, Dan

2018-03-21

To evaluate the ability of chromatic pupillometry to reveal abnormal pupillary responses to light in patients with early-stage primary open-angle glaucoma (POAG) and to test whether the degree of pupillometric impairment correlates with structural hallmarks of optic nerve damage in the disease. Cross-sectional study. Forty-six patients with early-stage POAG (63.4±8.3 years, 63% male, 87% ethnic-Chinese) and 90 age-matched healthy controls (61.4±8.6 years, 34% male, 89% ethnic-Chinese). Patients with POAG had a visual field mean deviation (VFMD) of -6 decibels or better on automated perimetry. Each participant underwent a monocular 2-minute exposure to blue light (462 nm) followed by another 2-minute exposure to red light (638 nm) using a modified Ganzfeld dome equipped with a light-emitting diode lighting system. The light stimuli intensity was increased logarithmically to evaluate the combined extrinsic and intrinsic response of intrinsically photosensitive retinal ganglion cells (ipRGCs). Light-induced changes in horizontal pupil diameter were assessed monocularly using infrared pupillography. Baseline-adjusted, light-induced pupillary constriction amplitudes were calculated, and individual irradiance-response curves were constructed for each stimulus. Pupillary constriction amplitudes were compared between groups and across light intensities using a linear mixed model analysis. The linear relationship between pupillometric parameters and different structural and functional features of glaucoma was assessed using Pearson's correlation analysis. Light-induced pupillary constriction was reduced in patients with early-stage POAG compared with controls at moderate to high irradiances (≥11 Log photons/cm 2 /s) of blue (P = 0.003) and red (P < 0.001) light. Maximal pupillary constriction amplitude was correlated with retinal nerve fiber layer thickness (RNFL) thickness (blue: r = 0.51, P < 0.001; red: r = 0.45, P = 0.002) in patients with POAG but not in controls. Conversely, pupillometric parameters were not correlated with visual field scores in patients with early-stage POAG. Patients with early-stage POAG exhibit reduced pupillary responses to moderate and high irradiances of blue and red lights. This wavelength-independent functional alteration correlates with structural thinning of the RNFL and could be the consequence of dysfunction or loss of melanopsin expressing ipRGCs in the early stages of the disease. Copyright © 2018 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Timing of Indonesian Gateway Restriction Between 4.0 and 2.8 Ma and its Impact on Indian Ocean Surface Waters Based on Calcareous Nannoplankton Assemblages

NASA Astrophysics Data System (ADS)

Auer, G.; De Vleeschouwer, D.; Groeneveld, J.; Bogus, K.; Henderiks, J.; Castañeda, I. S.; Expedition 356 Scientists, I.

2017-12-01

The Early Pliocene is characterized by a fundamental reorganization of Earth's climate. In particular, the ongoing constriction of the Indonesian Gateway (IG) around 4.0 - 3.0 Ma is commonly evoked cause for these climatic changes (Christensen et al., 2017; De Schepper et al., 2014; Karas et al., 2009; 2017). The constriction of the IG, caused by the northward movement of Australia and related uplift of Indonesia, had major effects on global climate and may have contributed to Northern Hemisphere cooling via complex atmospheric and oceanographic teleconnections. Untangling the exact timing of IG constriction is thus critical for resolving the mechanisms driving Earth's climatic evolution during the Pliocene. Here we present high-resolution reconstructions of surface water conditions and IG connectivity using calcareous nannoplankton (CNP) assemblages between 4.0 and 2.8 Ma at Site U1463 (18°59'S, 117°37'E; IODP Expedition 356). Located on the Northwest Shelf (NWS) of Australia, the site lies directly in the path of the upper branch of the Leeuwin-Holloway current, making it an ideal location to study Pliocene IG dynamics and their influence on the eastern Indian Ocean. Using modern analogue based interpretation of CNP assemblages, in combination with an independent orbitally tuned age model, shows a change in surface water conditions along the NWS 3.8 Ma recognizable by a decrease in tropical taxa like Umbilicosphaera sibogae and Sphenolithus spp. Subsequently, a shift from Gephyrocapsa sp. to Reticulofenestra sp. dominated CNP assemblages and the increase of mesotrophic CNP taxa (e.g. Umbilicosphaera jafari; Helicosphaera spp.), suggests that warm, stratified, oligotrophic (i.e. tropical) waters were replaced by cooler, more turbulent, and less saline waters by 3.8 - 3.6 Ma. We relate this switch in dominant water masses to changes in IG geometry delivering relatively cooler and fresher waters from northern Pacific sources to the NWS. The abundance of Calcidiscus leptoporus and overall decreasing CNP diversity, however, correlates with temperature records from the equatorial Indian Ocean. Combined with existing records, our data thus suggest that initial IG constriction occurred 3.8 - 3.75 Ma while also reflecting the response of the tropical Indian Ocean to cooling in the southern high latitudes.

Syn-Extensional Constrictional Folding of the Gwoira Rider Block, a Large Fault-Bounded Slice Atop the Mai'iu Low-Angle Normal Fault, Woodlark Rift.

NASA Astrophysics Data System (ADS)

Little, T. A.; Webber, S. M.; Norton, K. P.; Mizera, M.; Oesterle, J.; Ellis, S. M.

2016-12-01

The Mai'iu Fault is an active and corrugated low-angle normal fault (LANF) in Woodlark Rift, Eastern Papua New Guinea, which dips 21° NNE, accommodating rapid N-S extension. The Gwoira rider block is a large fault-bounded sedimentary slice comprising the Gwoira Conglomerate, located within a large synformal megamullion in the Mai'iu Fault surface. The Gwoira Conglomerate was originally deposited on the Mai'iu Fault hanging wall concurrent with extension, and has since been buried to a maximum depth of 1600-2100 m (evidenced by vitrinite reflectance data), back-tilted, and synformally folded. Both the Gwoira Conglomerate (former hanging wall) and mylonitic foliation (footwall) of the Mai'iu Fault have been shortened E-W, perpendicular to the extension direction. We show that E-W synformal folding of the Gwoira Conglomerate was concurrent with ongoing sedimentation and extension on the Mai'iu Fault. Structurally shallower Gwoira Conglomerate strata are folded less than deeper strata, indicating that folding was progressively accrued concurrent with N-S extension. We also show that abandonment of the inactive strand of the Mai'iu Fault in favor of the Gwoira Fault, which resulted in formation of the Gwoira rider block, occurred in response to progressive megamullion amplification and resultant misorientation of the inactive strand of the Mai'iu Fault. We attribute E-W folding to extension-perpendicular constriction. This is consistent with observations of outcrop-scale conjugate strike-slip faults that deform the footwall and hanging wall of the Mai'iu Fault, and accommodate E-W shortening. Constrictional folding remains active in the near-surface as evidenced by synformal tilting of inferred Late Quaternary fluvial terraces atop the Gwoira rider block. This sequence of progressive constrictional folding is dated using 26Al/10Be terrestrial cosmogenic nuclide burial dating of the Gwoira Conglomerate. Finally, because rider block formation records abandonment of the uppermost part of a LANF, Coulomb fault mechanical analysis (after Choi and Buck, 2012) can be applied to field observations to provide an upper limit on LANF frictional strength (µf). Modelling constrains the µf for the Mai'iu Fault to ≤0.25, which suggests that the Mai'iu Fault is frictionally very weak.

A Preliminary Videofluoroscopic Investigation of Swallowing Physiology and Function in Individuals with Oculopharyngeal Muscular Dystrophy (OPMD).

PubMed

Waito, Ashley A; Steele, Catriona M; Peladeau-Pigeon, Melanie; Genge, Angela; Argov, Zohar

2018-05-03

Dysphagia is one of the primary symptoms experienced by individuals with Oculopharyngeal Muscular Dystrophy (OPMD). However, we lack understanding of the discrete changes in swallowing physiology that are seen in OPMD, and the resulting relationship to impairments of swallowing safety and efficiency. This study sought to describe the pathophysiology of dysphagia in a small sample of patients with OPMD using a videofluoroscopy examination (VFSS) involving 3 × 5 mL boluses of thin liquid barium (22% w/v). The aim of this study is to extend what is known about the pathophysiology of dysphagia in OPMD, by quantifying changes in swallow timing, kinematics, safety, and efficiency, measured from VFSS. This study is a secondary analysis of baseline VFSS collected from 11 adults (4 male), aged 48-62 (mean 57) enrolled in an industry-sponsored phase 2 therapeutic drug trial. Blinded raters scored the VFSS recordings for safety [Penetration-Aspiration Scale (PAS)], efficiency [Normalized Residue Ratio Scale (NRRS)], timing [Pharyngeal Transit Time (PTT), Swallow Reaction Time (SRT), Laryngeal Vestibule Closure Reaction Time (LVCrt), Upper Esophageal Sphincter Opening Duration (UESD)], and kinematics (hyoid movement, pharyngeal constriction, UES opening width). Impairment thresholds from existing literature were defined to characterize swallowing physiology and function. Further, Fisher's Exact tests and Pearson's correlations were used to conduct a preliminary exploration of associations between swallowing physiology (e.g., kinematics, timing) and function (i.e., safety, efficiency). Compared to published norms, we identified significant differences in the degree of maximum pharyngeal constriction, hyoid movement distance and speed, as well as degree and timeliness of airway closure. Unsafe swallowing (PAS ≥ 3) was seen in only 3/11 patients. By contrast, clinically significant residue (i.e., NRRS scores ≥ 0.09 vallecular; ≥ 0.2 pyriform) was seen in 7/11 patients. Fisher's Exact tests revealed associations between prolonged SRT, PTT, and unsafe swallowing. Weak associations were also identified between post-swallow residue and poor pharyngeal constriction during the swallow. Detailed analysis of swallowing physiology in this series of adults with OPMD aligns with impaired muscular function (e.g., reduced pharyngeal constriction, incomplete laryngeal vestibule closure) associated with the disease, and primary functional challenges with swallow efficiency. Further work is needed to explore a greater range of food and liquid textures, and to identify additional physiological mechanisms underlying swallowing impairment in OPMD.

Nicotinamide Riboside Preserves Cardiac Function in a Mouse Model of Dilated Cardiomyopathy.

PubMed

Diguet, Nicolas; Trammell, Samuel A J; Tannous, Cynthia; Deloux, Robin; Piquereau, Jérôme; Mougenot, Nathalie; Gouge, Anne; Gressette, Mélanie; Manoury, Boris; Blanc, Jocelyne; Breton, Marie; Decaux, Jean-François; Lavery, Gareth G; Baczkó, István; Zoll, Joffrey; Garnier, Anne; Li, Zhenlin; Brenner, Charles; Mericskay, Mathias

2018-05-22

Myocardial metabolic impairment is a major feature in chronic heart failure. As the major coenzyme in fuel oxidation and oxidative phosphorylation and a substrate for enzymes signaling energy stress and oxidative stress response, nicotinamide adenine dinucleotide (NAD + ) is emerging as a metabolic target in a number of diseases including heart failure. Little is known on the mechanisms regulating homeostasis of NAD + in the failing heart. To explore possible alterations of NAD + homeostasis in the failing heart, we quantified the expression of NAD + biosynthetic enzymes in the human failing heart and in the heart of a mouse model of dilated cardiomyopathy (DCM) triggered by Serum Response Factor transcription factor depletion in the heart (SRF HKO ) or of cardiac hypertrophy triggered by transverse aorta constriction. We studied the impact of NAD + precursor supplementation on cardiac function in both mouse models. We observed a 30% loss in levels of NAD + in the murine failing heart of both DCM and transverse aorta constriction mice that was accompanied by a decrease in expression of the nicotinamide phosphoribosyltransferase enzyme that recycles the nicotinamide precursor, whereas the nicotinamide riboside kinase 2 (NMRK2) that phosphorylates the nicotinamide riboside precursor is increased, to a higher level in the DCM (40-fold) than in transverse aorta constriction (4-fold). This shift was also observed in human failing heart biopsies in comparison with nonfailing controls. We show that the Nmrk2 gene is an AMP-activated protein kinase and peroxisome proliferator-activated receptor α responsive gene that is activated by energy stress and NAD + depletion in isolated rat cardiomyocytes. Nicotinamide riboside efficiently rescues NAD + synthesis in response to FK866-mediated inhibition of nicotinamide phosphoribosyltransferase and stimulates glycolysis in cardiomyocytes. Accordingly, we show that nicotinamide riboside supplementation in food attenuates the development of heart failure in mice, more robustly in DCM, and partially after transverse aorta constriction, by stabilizing myocardial NAD + levels in the failing heart. Nicotinamide riboside treatment also robustly increases the myocardial levels of 3 metabolites, nicotinic acid adenine dinucleotide, methylnicotinamide, and N1-methyl-4-pyridone-5-carboxamide, that can be used as validation biomarkers for the treatment. The data show that nicotinamide riboside, the most energy-efficient among NAD precursors, could be useful for treatment of heart failure, notably in the context of DCM, a disease with few therapeutic options. © 2017 American Heart Association, Inc.

Augmented endothelial l-arginine transport ameliorates pressure-overload-induced cardiac hypertrophy.

PubMed

Rajapakse, Niwanthi W; Johnston, Tamara; Kiriazis, Helen; Chin-Dusting, Jaye P; Du, Xiao-Jun; Kaye, David M

2015-07-01

What is the central question of this study? What is the potential role of endothelial NO production via overexpression of the l-arginine transporter, CAT1, as a mitigator of cardiac hypertrophy? What is the main finding and its importance? Augmentation of endothelium-specific l-arginine transport via CAT1 can attenuate pressure-overload-dependent cardiac hypertrophy and fibrosis. Our findings support the conclusion that interventions that improve endothelial l-arginine transport may provide therapeutic utility in the setting of myocardial hypertrophy. Such modifications may be introduced by exercise training or locally delivered gene therapy, but further experimental and clinical studies are required. Endothelial dysfunction has been postulated to play a central role in the development of cardiac hypertrophy, probably as a result of reduced NO bioavailability. We tested the hypothesis that increased endothelial NO production, mediated by increased l-arginine transport, could attenuate pressure-overload-induced cardiac hypertrophy. Echocardiography and blood pressure measurements were performed 15 weeks after transverse aortic constriction (TAC) in wild-type (WT) mice (n = 12) and in mice with endothelium-specific overexpression of the l-arginine transporter, CAT1 (CAT+; n = 12). Transverse aortic constriction induced greater increases in heart weight to body weight ratio in WT (by 47%) than CAT+ mice (by 25%) compared with the respective controls (P ≤ 0.05). Likewise, the increase in left ventricular wall thickness induced by TAC was significantly attenuated in CAT+ mice (P = 0.05). Cardiac collagen type I mRNA expression was greater in WT mice with TAC (by 22%; P = 0.03), but not in CAT+ mice with TAC, compared with the respective controls. Transverse aortic constriction also induced lesser increases in β-myosin heavy chain mRNA expression in CAT+ mice compared with WT (P ≤ 0.05). Left ventricular systolic pressure after TAC was 36 and 39% greater in WT and CAT+ mice, respectively, compared with the respective controls (P ≤ 0.001). Transverse aortic constriction had little effect on left ventricular end-diastolic pressure in both genotypes. Taken together, these data indicate that augmenting endothelial function by overexpression of l-arginine transport can attenuate pressure-overload-induced cardiac hypertrophy. © 2015 The Authors. Experimental Physiology © 2015 The Physiological Society.

Influence of G-forces on the blood vessels in the nervous system of the rabbit

NASA Technical Reports Server (NTRS)

Zotova, N. I.; Muratikova, V. A.; Preobrazhenskaya, I. N.

1975-01-01

Arteries in the brain are constricted by g-forces applied in the head-pelvis direction. Transversely applied g-forces have less effect. Appropriate conditioning can reduce the severity of all g-force applications.

WHO ARE THE DISADVANTAGED.

ERIC Educational Resources Information Center

ORNSTEIN, ALLAN C.

THIS ARTICLE DISCUSSES SOME SPECIFIC ASPECTS OF THE INDIVIDUAL, SOCIAL, ENVIRONMENTAL, PARENTAL AND HYGIENIC DEPRIVATIONS OF DISADVANTAGED YOUTH. ALSO NOTED ARE DEPRIVATIONS THAT RESULT FROM RACE, CONSTRICTED EXPERIENCE, AND EDUCATIONAL HANDICAPS. EDUCATION IS CONSIDERED THE MOST IMPORTANT MEANS OF BREAKING THROUGH THE COMPLEX CYCLE OF POVERTY AND…

Reframing the Person-In-Environment Perspective.

ERIC Educational Resources Information Center

Weick, Ann

1981-01-01

An emphasis on psychological aspects of behavior has constricted social work's view of the social environment and narrowed its theoretical base for intervention. Broadening perceptions to include the physical and social environment is critical in establishing a synthesis between the individual and society. (Author/RC)

Mitigation of ergot vasoconstriction by clover isoflavones in goats (Capra hircus)

USDA-ARS?s Scientific Manuscript database

Ergot alkaloids produced by a fungal endophyte (Epichloë coenophiala; formerly Neotyphodium coenphialum) that infects tall fescue (Lolium arundinaceum) can induce persistent constriction of the vasculature in ruminants, hindering their capability to thermo-regulate core body temperature. There is e...

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

Ledee, Dolena R.; Smith, Lincoln; Kajimoto, Masaki

Pressure overload cardiac hypertrophy alters substrate metabolism. Prior work showed that myocardial inactivation of c-Myc (Myc) attenuated hypertrophy and decreased expression of glycolytic 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 FVB mice with cardiac specific, inducible Myc inactivation (MycKO-TAC) and non-transgenic littermates (Cont-TAC) to transverse aortic constriction (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, ketones and unlabeled glucose and insulin. Western blots were used to evaluate metabolic enzymes. 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 (presumably glucose) contribution. Myc inactivation (MycKO-TAC) inhibited these metabolic changes. Hypertrophy in general increased protein levels of PKM2; however this change was not linked to Myc status. Protein post-translation modification by O-GlcNAc was significantly greater in Cont-TAC versus both Sham and MycKO-TAC. In conclusion, Myc regulates substrate utilization during early pressure overload hypertrophy. Our results show that the metabolic switch during hypertrophy is not necessary to maintain cardiac function, but it may be important mechanism to promote cardiomyocyte growth. Myc also regulates protein O-GlcNAcylation during hypertrophy.« less

Design of microfluidic channels for magnetic separation of malaria-infected red blood cells

PubMed Central

Wu, Wei-Tao; Martin, Andrea Blue; Gandini, Alberto; Aubry, Nadine; Massoudi, Mehrdad; Antaki, James F.

2016-01-01

This study is motivated by the development of a blood cell filtration device for removal of malaria-infected, parasitized red blood cells (pRBCs). The blood was modeled as a multi-component fluid using the computational fluid dynamics discrete element method (CFD-DEM), wherein plasma was treated as a Newtonian fluid and the red blood cells (RBCs) were modeled as soft-sphere solid particles which move under the influence of drag, collisions with other RBCs, and a magnetic force. The CFD-DEM model was first validated by a comparison with experimental data from Han et al. 2006 (Han and Frazier 2006) involving a microfluidic magnetophoretic separator for paramagnetic deoxygenated blood cells. The computational model was then applied to a parametric study of a parallel-plate separator having hematocrit of 40% with a 10% of the RBCs as pRBCs. Specifically, we investigated the hypothesis of introducing an upstream constriction to the channel to divert the magnetic cells within the near-wall layer where the magnetic force is greatest. Simulations compared the efficacy of various geometries upon the stratification efficiency of the pRBCs. For a channel with nominal height of 100 µm, the addition of an upstream constriction of 80% improved the proportion of pRBCs retained adjacent to the magnetic wall (separation efficiency) by almost 2 fold, from 26% to 49%. Further addition of a downstream diffuser reduced remixing, hence improved separation efficiency to 72%. The constriction introduced a greater pressure drop (from 17 to 495 Pa), which should be considered when scaling-up this design for a clinical-sized system. Overall, the advantages of this design include its ability to accommodate physiological hematocrit and high throughput – which is critical for clinical implementation as a blood-filtration system. PMID:27761107

Lysine and the Na+/K+ Selectivity in Mammalian Voltage-Gated Sodium Channels.

PubMed

Li, Yang; Liu, Huihui; Xia, Mengdie; Gong, Haipeng

2016-01-01

Voltage-gated sodium (Nav) channels are critical in the generation and transmission of neuronal signals in mammals. The crystal structures of several prokaryotic Nav channels determined in recent years inspire the mechanistic studies on their selection upon the permeable cations (especially between Na+ and K+ ions), a property that is proposed to be mainly determined by residues in the selectivity filter. However, the mechanism of cation selection in mammalian Nav channels lacks direct explanation at atomic level due to the difference in amino acid sequences between mammalian and prokaryotic Nav homologues, especially at the constriction site where the DEKA motif has been identified to determine the Na+/K+ selectivity in mammalian Nav channels but is completely absent in the prokaryotic counterparts. Among the DEKA residues, Lys is of the most importance since its mutation to Arg abolishes the Na+/K+ selectivity. In this work, we modeled the pore domain of mammalian Nav channels by mutating the four residues at the constriction site of a prokaryotic Nav channel (NavRh) to DEKA, and then mechanistically investigated the contribution of Lys in cation selection using molecular dynamics simulations. The DERA mutant was generated as a comparison to understand the loss of ion selectivity caused by the K-to-R mutation. Simulations and free energy calculations on the mutants indicate that Lys facilitates Na+/K+ selection by electrostatically repelling the cation to a highly Na+-selective location sandwiched by the carboxylate groups of Asp and Glu at the constriction site. In contrast, the electrostatic repulsion is substantially weakened when Lys is mutated to Arg, because of two intrinsic properties of the Arg side chain: the planar geometric design and the sparse charge distribution of the guanidine group.

Effects of exposure to intermittent versus continuous red light on human circadian rhythms, melatonin suppression, and pupillary constriction.

PubMed

Ho Mien, Ivan; Chua, Eric Chern-Pin; Lau, Pauline; Tan, Luuan-Chin; Lee, Ivan Tian-Guang; Yeo, Sing-Chen; Tan, Sara Shuhui; Gooley, Joshua J

2014-01-01

Exposure to light is a major determinant of sleep timing and hormonal rhythms. The role of retinal cones in regulating circadian physiology remains unclear, however, as most studies have used light exposures that also activate the photopigment melanopsin. Here, we tested the hypothesis that exposure to alternating red light and darkness can enhance circadian resetting responses in humans by repeatedly activating cone photoreceptors. In a between-subjects study, healthy volunteers (n = 24, 21-28 yr) lived individually in a laboratory for 6 consecutive days. Circadian rhythms of melatonin, cortisol, body temperature, and heart rate were assessed before and after exposure to 6 h of continuous red light (631 nm, 13 log photons cm(-2) s(-1)), intermittent red light (1 min on/off), or bright white light (2,500 lux) near the onset of nocturnal melatonin secretion (n = 8 in each group). Melatonin suppression and pupillary constriction were also assessed during light exposure. We found that circadian resetting responses were similar for exposure to continuous versus intermittent red light (P = 0.69), with an average phase delay shift of almost an hour. Surprisingly, 2 subjects who were exposed to red light exhibited circadian responses similar in magnitude to those who were exposed to bright white light. Red light also elicited prolonged pupillary constriction, but did not suppress melatonin levels. These findings suggest that, for red light stimuli outside the range of sensitivity for melanopsin, cone photoreceptors can mediate circadian phase resetting of physiologic rhythms in some individuals. Our results also show that sensitivity thresholds differ across non-visual light responses, suggesting that cones may contribute differentially to circadian resetting, melatonin suppression, and the pupillary light reflex during exposure to continuous light.

Tidal stretches do not modulate responsiveness of intact airways in vitro

PubMed Central

Szabo, Thomas L.; Suki, Béla; Lutchen, Kenneth R.

2010-01-01

Studies on isolated tracheal airway smooth muscle (ASM) strips have shown that length/force fluctuations, similar to those likely occurring during breathing, will mitigate ASM contractility. These studies conjecture that, solely by reducing length oscillations on a healthy, intact airway, one can create airway hyperresponsiveness, but this has never been explicitly tested. The intact airway has additional complexities of geometry and structure that may impact its relevance to isolated ASM strips. We examined the role of transmural pressure (Ptm) fluctuations of physiological amplitudes on the responsiveness of an intact airway. We developed an integrated system utilizing ultrasound imaging to provide real-time measurements of luminal radius and wall thickness over the full length of an intact airway (generation 10 and below) during Ptm oscillations. First, airway constriction dynamics to cumulative acetylcholine (ACh) doses (10−7 to 10−3 M) were measured during static and dynamic Ptm protocols. Regardless of the breathing pattern, the Ptm oscillation protocols were ineffective in reducing the net level of constriction for any ACh dose, compared with the static control (P = 0.225–0.793). Next, Ptm oscillations of increasing peak-to-peak amplitude were applied subsequent to constricting intact airways under static conditions (5.0-cmH2O Ptm) with a moderate ACh dose (10−5 M). Peak-to-peak Ptm oscillations ≤5.0 cmH2O resulted in no statistically significant bronchodilatory response (P = 0.429 and 0.490). Larger oscillations (10 cmH2O, peak to peak) produced modest dilation of 4.3% (P = 0.009). The lack of modulation of airway responsiveness by Ptm oscillations in intact, healthy airways suggests that ASM level mechanisms alone may not be the sole determinant of airway responsiveness. PMID:20431023

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

PubMed Central

2014-01-01

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

Polycystin-1 Is a Cardiomyocyte Mechanosensor That Governs L-Type Ca2+ Channel Protein Stability.

PubMed

Pedrozo, Zully; Criollo, Alfredo; Battiprolu, Pavan K; Morales, Cyndi R; Contreras-Ferrat, Ariel; Fernández, Carolina; Jiang, Nan; Luo, Xiang; Caplan, Michael J; Somlo, Stefan; Rothermel, Beverly A; Gillette, Thomas G; Lavandero, Sergio; Hill, Joseph A

2015-06-16

L-type calcium channel activity is critical to afterload-induced hypertrophic growth of the heart. However, the mechanisms governing mechanical stress-induced activation of L-type calcium channel activity are obscure. Polycystin-1 (PC-1) is a G protein-coupled receptor-like protein that functions as a mechanosensor in a variety of cell types and is present in cardiomyocytes. We subjected neonatal rat ventricular myocytes to mechanical stretch by exposing them to hypo-osmotic medium or cyclic mechanical stretch, triggering cell growth in a manner dependent on L-type calcium channel activity. RNAi-dependent knockdown of PC-1 blocked this hypertrophy. Overexpression of a C-terminal fragment of PC-1 was sufficient to trigger neonatal rat ventricular myocyte hypertrophy. Exposing neonatal rat ventricular myocytes to hypo-osmotic medium resulted in an increase in α1C protein levels, a response that was prevented by PC-1 knockdown. MG132, a proteasomal inhibitor, rescued PC-1 knockdown-dependent declines in α1C protein. To test this in vivo, we engineered mice harboring conditional silencing of PC-1 selectively in cardiomyocytes (PC-1 knockout) and subjected them to mechanical stress in vivo (transverse aortic constriction). At baseline, PC-1 knockout mice manifested decreased cardiac function relative to littermate controls, and α1C L-type calcium channel protein levels were significantly lower in PC-1 knockout hearts. Whereas control mice manifested robust transverse aortic constriction-induced increases in cardiac mass, PC-1 knockout mice showed no significant growth. Likewise, transverse aortic constriction-elicited increases in hypertrophic markers and interstitial fibrosis were blunted in the knockout animals PC-1 is a cardiomyocyte mechanosensor that is required for cardiac hypertrophy through a mechanism that involves stabilization of α1C protein. © 2015 American Heart Association, Inc.

Evaluation of the Analgesic Activity of the Methanolic Stem Bark Extract of Dialium Guineense (Wild)

PubMed Central

Ezeja, MI; Omeh, YS; Ezeigbo, II; Ekechukwu, A

2011-01-01

Background: Dialium guineense is a medicinal plant used by some communities of Enugu-Ezike in Enugu State, Nigeria for treatment of fever, headache and other diverse ailments. Objectives: The present study evaluated the analgesic activity of the methanolic stem bark extract of the plant. Method: Acetic acid-induced abdominal constriction or writhing, tail immersion and hot plate analgesic models in albino Wistar mice were used for the study. Three test doses (250, 500, 1000 mg/kg body weight) of the extract were administered orally by gastric gavage. The activity was compared with a standard reference drug, acetylsalicylic acid (aspirin) (400 mg/kg) and negative control. The results were analysed by SPSS version 17 using ANOVA and Post Hoc Duncan. Result: In the acetic acid-induced writhing reflex model, D. guineense extract and the reference drug significantly (P =0.014 - 0.002) decreased the mean total number of abdominal constriction in the mice in a dose dependent fashion. The percentage inhibition of the abdominal constriction reflex was increased dose dependently from 0% in the negative control group to 71% at the highest dose of the extract (1000mg/kg). In the tail immersion model the extract at the dose of 1000 mg/kg significantly (P = 0. 048) increased the pain reaction time (PRT) while in hot plate model the extract and drug also significantly (P = 0.048 - 0.05) increased the mean PRT at the doses of 500 and 1000 mg/kg. The dose of 250 mg/kg showed no analgesic activity in tail immersion and hot plate models. Conclusion: Dialium guineense demonstrated significant analgesic activity that may be mediated through peripheral pain mechanism. PMID:23209955

Evaluation of the analgesic activity of the methanolic stem bark extract of dialium guineense (wild).

PubMed

Ezeja, Mi; Omeh, Ys; Ezeigbo, Ii; Ekechukwu, A

2011-01-01

Dialium guineense is a medicinal plant used by some communities of Enugu-Ezike in Enugu State, Nigeria for treatment of fever, headache and other diverse ailments. The present study evaluated the analgesic activity of the methanolic stem bark extract of the plant. Acetic acid-induced abdominal constriction or writhing, tail immersion and hot plate analgesic models in albino Wistar mice were used for the study. Three test doses (250, 500, 1000 mg/kg body weight) of the extract were administered orally by gastric gavage. The activity was compared with a standard reference drug, acetylsalicylic acid (aspirin) (400 mg/kg) and negative control. The results were analysed by SPSS version 17 using ANOVA and Post Hoc Duncan. In the acetic acid-induced writhing reflex model, D. guineense extract and the reference drug significantly (P =0.014 - 0.002) decreased the mean total number of abdominal constriction in the mice in a dose dependent fashion. The percentage inhibition of the abdominal constriction reflex was increased dose dependently from 0% in the negative control group to 71% at the highest dose of the extract (1000mg/kg). In the tail immersion model the extract at the dose of 1000 mg/kg significantly (P = 0. 048) increased the pain reaction time (PRT) while in hot plate model the extract and drug also significantly (P = 0.048 - 0.05) increased the mean PRT at the doses of 500 and 1000 mg/kg. The dose of 250 mg/kg showed no analgesic activity in tail immersion and hot plate models. Dialium guineense demonstrated significant analgesic activity that may be mediated through peripheral pain mechanism.

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.

Alterations to Swallowing Physiology as the Result of Effortful Swallowing in Healthy Seniors.

PubMed

Molfenter, Sonja M; Hsu, Chuan-Ya; Lu, Ying; Lazarus, Cathy L

2018-06-01

A significant proportion of healthy seniors report difficulty swallowing, thought to result from age-related decline in muscle bulk/function. Effortful Swallowing (ES) is used both as a compensatory maneuver to improve pharyngeal propulsion/clearance and has been proposed as an exercise to improve pharyngeal strength. This study sought to quantify the immediate kinematic, temporal, and functional changes during an ES maneuver to quantify its exercise potential to combat age-related changes in swallowing. Videofluoroscopy data were collected from 44 healthy seniors (21 male) over 65 years old (mean = 76.9, SD = 7.1). Each participant swallowed six 5 ml boluses of Varibar nectar-thick liquids: three with regular effort and three using ES. Individual swallows (n = 260) were measured on pharyngeal constriction, pharyngeal shortening, laryngeal closure duration, hyoid movement duration, UES opening duration, stage transition duration, pharyngeal transit time, pharyngeal response duration, Normalized Residue Ratio Scale (NRRS), and the Penetration-Aspiration Scale (PAS). Non-parametric Wilcoxon Rank Sum for repeated measures tested the effect of ES on each outcome. Exact p-values were calculated based on permutation methods, individual p values < 0.008 was deemed to be significant. The ES maneuver significantly prolonged all temporal variables. While we found no significant differences for pharyngeal constriction, significantly less (i.e., worse) pharyngeal shortening was observed in ES condition compared with regular effort swallows. Further, significantly worse pyriform sinus residue (NRRSv) was observed in the ES condition. No differences between ES and regular effort swallows were noted for pharyngeal constriction, NRRSv or PAS. We speculate that these negative manifestations of worse kinematics (less pharyngeal shortening) and function (increase in NRRSp) may be the result of forced volitional manipulation of swallowing in the ES condition in an otherwise normal elderly swallow.

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

Overexpression of SARAF Ameliorates Pressure Overload-Induced Cardiac Hypertrophy Through Suppressing STIM1-Orai1 in Mice.

PubMed

Dai, Fengdan; Zhang, Yan; Wang, Qiang; Li, De; Yang, Yongjian; Ma, Shuangtao; Yang, Dachun

2018-01-01

Activation of stromal interaction molecule 1 (STIM1) and Orai1 participates in the development of cardiac hypertrophy. Store-operated Ca2+ entry-associated regulatory factor (SARAF) is an intrinsic inhibitor of STIM1-Orai1 interaction. Thus, we hypothesized that SARAF could prevent cardiac hypertrophy. Male C57BL/6 mice, aged 8 weeks, were randomly divided into sham and abdominal aortic constriction surgery groups and were infected with lentiviruses expressing SARAF and GFP (Lenti-SARAF) or GFP alone (Lenti-GFP) via intramyocardial injection. At 4 weeks after aortic constriction, left ventricular structure and function were assessed by echocardiography and hemodynamic assays. The gene and protein expressions of SARAF, STIM1, and Orai1 were measured by quantitative PCR and Western blot, respectively. Gene and protein expressions of SARAF were significantly decreased, while STIM1 and Orai1 were increased in the heart tissue compared with sham group. Overexpression of SARAF in the heart prevented the upregulation of STIM1 and Orai1, and importantly, attenuated aortic constriction-induced decrease in maximal rate of left ventricular pressure decay and increases in thickness of interventricular septum and left ventricular posterior wall, heart weight/body weight ratio, and size of cardiomyocytes. Blood pressure detected through the carotid artery and left ventricular systolic function were not affected by SARAF overexpression. In addition, overexpression of SARAF also attenuated angiotensin II-induced upregulation of STIM1 and Orai1 and hypertrophy of cultured cardiomyocytes. Overexpression of SARAF in the heart prevents cardiac hypertrophy, probably through suppressing the upregulation of STIM1/Orai1. © 2018 The Author(s). Published by S. Karger AG, Basel.

The Sensitivity of Clinical Outcomes to Centration on the Light-Constricted Pupil for a Shape-Changing Corneal Inlay.

PubMed

Barragán-Garza, Enrique; Koch, Douglas D; Vargas, Luis G; Lang, Alan; Roy, Adam

2018-03-01

To assess the clinically acceptable range of inlay decentration with respect to the light-constricted pupil center and the coaxially sighted corneal light reflex (CSCLR) for an inlay (Raindrop Near Vision Inlay; ReVision Optics, Inc., Lake Forest, CA) that reshapes the anterior corneal surface. In this retrospective, observational cohort study of 115 patients with emmetropic or low hyperopic presbyopia who were implanted with a shape-changing corneal inlay, visual acuity, task performance (in good and dim light), reports of halos and glare, and satisfaction data were collected from the preoperative and 3-month postoperative examinations. Inlay centration with respect to the pupil center and CSCLR was determined from the center of the inlay effect derived from iTrace (Tracey Technologies, Houston, TX) wavefront measurements. Multivariate regression models assessed the influence of inlay position on visual outcomes. On average, monocular uncorrected near visual acuity (UNVA) improved 4.9 ± 1.7 lines in the treated eye, with no loss in binocular distance vision. Eighty-three percent of implants were centered radially within 0.5 mm of the pupil center. Multivariate analysis of decentration with respect to both the pupil center and CSCLR revealed no significant interaction with the above clinical outcomes, with the exception of UNVA in the treated eye (all P > .05, α = 0.05). For decentration of less than 0.75 mm, the change in UNVA was less than 1 line. Distance and near visual acuity, task performance, severity of halos and glare, and satisfaction were independent of radial decentration of the Raindrop Near Vision Inlay of less than 0.75 mm from the light-constricted pupil. [J Refract Surg. 2018;34(3):164-170.]. Copyright 2018, SLACK Incorporated.

Airway disease: anatomopathologic patterns and functional correlations.

PubMed

Mormile, F; Ciappi, G

1997-01-01

Airways represent a serial and parallel branched system, through which the alveoli are connected with the external air. They participate in the mechanical and immune defense against noxious agents, regional flow regulation to optimize the perfusion/ventilation ratio and provide lung mechanical support. Functional exploration of central airways is based on resistance measurement, flow-volume curve or spirometry, while peripheral airways influence parameters as the upstream resistance, the slope of phase III nitrogen washout and the residual volume. Bronchodynamic tests supply important information on airway reversibility and nonspecific reactivity. Anatomopathologic alterations of obstructive chronic bronchitis, pulmonary emphysema and bronchial asthma account for their specific functional and bronchodynamic alterations. There is a growing interest for bronchiolitis in the clinical, radiologic and functional field. This type of lesion, always present in COPD, asthma and interstitial disease, becomes relevant when isolated or predominant. The most useful anatomofunctional classification separates the "constrictive" forms, the cause of obstruction and hyperinflation, from "proliferative" forms where an intraluminal proliferation more or less extended to alveolar air spaces as in BOOP (bronchiolitis obliterans organizing pneumonia) results in restrictive dysfunction. Constrictive bronchiolitis obliterans represents a severe and frequent complication of lung and bone marrow transplantation. Idiopathic BOOP may occur with cough or flue-like symptoms. In other cases, constrictive and proliferative forms may have a toxic (gases or drugs), postinfective or immune etiology (rheumatoid arthritis, LES, etc). Respiratory bronchiolitis or smokers' bronchiolitis, an often asymptomatic lesion, rarely associated to an interstitial lung disease, should be considered separately. The relationships between respiratory bronchiolitis, COPD and initial centriacinar emphysema is still to be elucidated. The diagnostic combination of the more sensitive functional tests with HRCT will allow a better understanding of the natural history of the various forms of bronchiolitis.

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

Prenatal Effects of Maternal Consumption of Polyphenol-Rich Foods in Late Pregnancy upon Fetal Ductus Arteriosus

PubMed Central

Zielinsky, Paulo; Busato, Stefano

2013-01-01

Fetal circulation has characteristic features, being morphologically and functionally different from extrauterine circulation. The ductus arteriosus plays a fundamental role in directing the blood flow to fetal inferior body parts. Basically, the ductus arteriosus directs 80–85% of the right ventricular output arising from the superior vena cava, coronary sinus, and a small part from the inferior vena cava to descending aorta. Its histological structure is made up predominantly by a thick muscular layer, differently from the aorta and the pulmonary artery, which increases with gestational age. The fibers have a circumferential orientation, especially at the external layers, facilitating and making effective ductal constriction. These factors may generate lumen alterations which may cause fetal and neonatal complications, such as heart failure, hydrops, neonatal pulmonary hypertension, and even death. Classically, maternal administration of indomethacin and/or other antiinflammatory drugs interfere in prostaglandins metabolism, causing ductal constriction. However, many cases of fetal ductal constriction, as well as of persistent neonatal pulmonary artery hypertension, remain without an established etiology, being referred as “idiopathic.” In recent years, a growing body of evidence has shown that herbs, fruits, nuts, and a wide diversity of substances commonly used in daily diets have definitive effects upon the metabolic pathway of inflammation, with consequent inhibition of prostaglandins synthesis. This antiinflammatory action, especially of polyphenols, when ingested during the third trimester of pregnancy, may influence the dynamics of fetal ductus arteriosus flow. The goal of this review is to present these new observations and findings, which may influence dietary orientation during pregnancy. Birth Defects Research (Part C) 99:256–274, 2013. © 2013 Wiley Periodicals, Inc. PMID:24339037

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.

Characterization of biosynthesis and modes of action of prostaglandin E2 and prostacyclin in guinea pig mesenteric lymphatic vessels.

PubMed

Rehal, Sonia; Blanckaert, Pauline; Roizes, Simon; von der Weid, Pierre-Yves

2009-12-01

Rhythmical transient constrictions of the lymphatic vessels provide the means for efficient lymph drainage and interstitial tissue fluid balance. This activity is critical during inflammation, to avoid or limit oedema resulting from increased vascular permeability, mediated by the release of various inflammatory mediators. In this study, we investigated the mechanisms by which prostaglandin E(2) (PGE(2)) and prostacyclin modulate lymphatic contractility in isolated guinea pig mesenteric lymphatic vessels. Quantitative RT-PCR was used to assess the expression of mRNA for enzymes and receptors involved in the production and action of PGE(2) and prostacyclin in mesenteric collecting lymphatic vessels. Frequency and amplitude of lymphatic vessel constriction were measured in the presence of these prostaglandins and the role of their respective EP and IP receptors assessed. Prostaglandin E(2) and prostacyclin decreased concentration-dependently the frequency, without affecting the amplitude, of lymphatic constriction. Data obtained in the presence of the EP(4) receptor antagonists, GW627368x (1 microM) and AH23848B (30 microM) and the IP receptor antagonist CAY10441 (0.1 microM) suggest that PGE(2) predominantly activates EP(4), whereas prostacyclin mainly stimulates IP receptors. Inhibition of responses to either prostaglandin with H89 (10 microM) or glibenclamide (1 microM) suggested a role for the activation of protein kinase A and ATP-sensitive K(+) channels. Our findings characterized the inhibition of lymphatic pumping induced by PGE(2) or prostacyclin in guinea pig mesenteric lymphatics. This action is likely to impair oedema resolution and to contribute to the pro-inflammatory actions of these prostaglandins.

Micro-Computed Tomography Analysis of the Root Canal Morphology of Palatal Roots of Maxillary First Molars.

PubMed

Marceliano-Alves, Marília; Alves, Flávio Rodrigues Ferreira; Mendes, Daniel de Melo; Provenzano, José Claudio

2016-02-01

A thorough knowledge of root canal anatomy is critical for successful root canal treatments. This study evaluated the internal anatomy of the palatal roots of maxillary first molars with micro-computed tomography (microCT). The palatal roots of extracted maxillary first molars (n = 169) were scanned with microCT to determine several anatomic parameters, including main canal classification, lateral canal occurrence and location, degree of curvature, main foramen position, apical constriction presence, diameters 1 and 2 mm from the apex and 1 mm from the foramen, minor dentin thickness in those regions, canal volume, surface area, and convexity. All canals were classified as Vertucci type I. The cross sections were oval in 61% of the canals. Lateral canals were found in 25% of the samples. The main foramen did not coincide with the root apex in 95% of the cases. Only 8% of the canals were classified as straight. Apical constriction was identified in 38% of the roots. The minor and major canal diameters and minor dentin thickness were decreased near the apex. The minor dentin thickness 1 mm from the foramen was 0.82 mm. The palatal canals exhibited a volume of 6.91 mm(3) and surface area of 55.31 mm(2) and were rod-shaped. The root canals of the palatal roots were classified as type I. However, some factors need to be considered during the treatment of these roots, including the frequent ocurrence of moderate/severe curvatures, oval-shaped cross-sections, and lateral canals, noncoincidence of the apical foramen with the root apex, and absence of apical constriction in most cases. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.