Transformation of dilative and contractive landslide debris into debris flows-An example from marin County, California

USGS Publications Warehouse

Fleming, R.W.; Ellen, S.D.; Algus, M.A.

1989-01-01

The severe rainstorm of January 3, 4 and 5, 1982, in the San Francisco Bay area, California, produced numerous landslides, many of which transformed into damaging debris flows. The process of transformation was studied in detail at one site where only part of a landslide mobilized into several episodes of debris flow. The focus of our investigation was to learn whether the landslide debris dilated or contracted during the transformation from slide to flow. The landslide debris consisted of sandy colluvium that was separable into three soil horizons that occupied the axis of a small topographic swale. Failure involved the entire thickness of colluvium; however, over parts of the landslide, the soil A-horizon failed separately from the remainder of the colluvium. Undisturbed samples were taken for density measurements from outside the landslide, from the failure zone and overlying material from the part of the landslide that did not mobilize into debris flows, and from the debris-flow deposits. The soil A-horizon was contractive and mobilized to flows in a process analogous to liquefaction of loose, granular soils during earthquakes. The soil B- and C-horizons were dilative and underwent 2 to 5% volumetric expansion during landslide movement that permitted mobilization of debris-flow episodes. Several criteria can be used in the field to differentiate between contractive and dilative behavior including lag time between landsliding and mobilization of flow, episodic mobilization of flows, and partial or complete transformation of the landslide. ?? 1989.

Using multiple bed load measurements: Toward the identification of bed dilation and contraction in gravel-bed rivers

NASA Astrophysics Data System (ADS)

Marquis, G. A.; Roy, A. G.

2012-02-01

This study examines bed load transport processes in a small gravel-bed river (Béard Creek, Québec) using three complementary methods: bed elevation changes between successive floods, bed activity surveys using tags inserted into the bed, and bed load transport rates from bed load traps. The analysis of 20 flood events capable of mobilizing bed material led to the identification of divergent results among the methods. In particular, bed elevation changes were not consistent with the bed activity surveys. In many cases, bed elevation changes were significant (1 to 2 times the D50) even if the bed surface had not been activated during the flood, leading to the identification of processes of bed dilation and contraction that occurred over 10% to 40% of the bed surface. These dynamics of the river bed prevent accurate derivation of bed load transport rates from topographic changes, especially for low magnitude floods. This paper discusses the mechanisms that could explain the dilation and contraction of particles within the bed and their implications in fluvial dynamics. Bed contraction seems to be the result of the winnowing of the fine sediments under very low gravel transport. Bed dilation seems to occur on patches of the bed at the threshold of motion where various processes such as fine sediment infiltration lead to the maintenance of a larger sediment framework volume. Both processes are also influenced by flood history and the initial local bed state and in turn may have a significant impact on sediment transport and morphological changes in gravel-bed rivers.

Vaginal dilator therapy for women receiving pelvic radiotherapy.

PubMed

Miles, Tracie; Johnson, Nick

2014-09-08

Vaginal dilation therapy is advocated after pelvic radiotherapy to prevent stenosis (abnormal narrowing of the vagina), but can be uncomfortable and psychologically distressing. To assess the benefits and harms of different types of vaginal dilation methods offered to women treated by pelvic radiotherapy for cancer. Searches included the Cochrane Central Register of Controlled Trials (CENTRAL 2013, Issue 5), MEDLINE (1950 to June week 2, 2013), EMBASE (1980 to 2013 week 24) and CINAHL (1982 to 2013). Comparative data of any type, which evaluated dilation or penetration of the vagina after pelvic radiotherapy treatment for cancer. Two review authors independently assessed whether potentially relevant studies met the inclusion criteria. We found no trials and therefore analysed no data. We identified no studies for inclusion in the original review or for this update. However, we felt that some studies that were excluded warranted discussion. These included one randomised trial (RCT), which showed no improvement in sexual scores associated with encouraging women to practise dilation therapy; a recent small RCT that did not show any advantage to dilation over vibration therapy during radiotherapy; two non-randomised comparative studies; and five correlation studies. One of these showed that objective measurements of vaginal elasticity and length were not linked to dilation during radiotherapy, but the study lacked power. One study showed that women who dilated tolerated a larger dilator, but the risk of objectivity and bias with historical controls was high. Another study showed that the vaginal measurements increased in length by a mean of 3 cm after dilation was introduced 6 to 10 weeks after radiotherapy, but there was no control group; another case series showed the opposite. Three recent studies showed less stenosis associated with prophylactic dilation after radiotherapy. One small case series suggested that dilation years after radiotherapy might restore the vagina to a functional length. There is no reliable evidence to show that routine, regular vaginal dilation during radiotherapy treatment prevents stenosis or improves quality of life. Several observational studies have examined the effect of dilation therapy after radiotherapy. They suggest that frequent dilation practice is associated with lower rates of self reported stenosis. This could be because dilation is effective or because women with a healthy vagina are more likely to comply with dilation therapy instructions compared to women with strictures. We would normally suggest that a RCT is needed to distinguish between a casual and causative link, but pilot studies highlight many reasons why RCT methodology is challenging in this area.

Observers' measurements in premetric electrodynamics: Time and radar length

NASA Astrophysics Data System (ADS)

Gürlebeck, Norman; Pfeifer, Christian

2018-04-01

The description of an observer's measurement in general relativity and the standard model of particle physics is closely related to the spacetime metric. In order to understand and interpret measurements, which test the metric structure of the spacetime, like the classical Michelson-Morley, Ives-Stilwell, Kennedy-Thorndike experiments or frequency comparison experiments in general, it is necessary to describe them in theories, which go beyond the Lorentzian metric structure. However, this requires a description of an observer's measurement without relying on a metric. We provide such a description of an observer's measurement of the fundamental quantities time and length derived from a premetric perturbation of Maxwell's electrodynamics and a discussion on how these measurements influence classical relativistic observables like time dilation and length contraction. Most importantly, we find that the modification of electrodynamics influences the measurements at two instances: the propagation of light is altered as well as the observer's proper time normalization. When interpreting the results of a specific experiment, both effects cannot be disentangled, in general, and have to be taken into account.

Differences in stone size and ureteral dilation between obstructing proximal and distal ureteral calculi.

PubMed

Eisner, Brian H; Pedro, Renato; Namasivayam, Saravanan; Kambadakone, Avinash; Sahani, Dushyant V; Dretler, Stephen P; Monga, Manoj

2008-09-01

To examine the differences in ureteral dilation and calculus size between obstructing proximal and distal ureteral stones. A retrospective review of computed tomography (CT) scans from 176 consecutive patients with obstructing ureteral calculi was performed. For the calculi, the axial diameter was defined as the largest stone diameter on the axial CT images, and the coronal length was defined as the cephalocaudal length of the stone measured on the coronal CT images. Univariate and multivariate statistical analyses were performed. A total of 65 proximal and 111 distal ureteral calculi were analyzed. On univariate analysis, the proximal calculi were associated with a greater degree of ureteral dilation (mean 6.1 mm vs 5.3 mm, P = .01) and had a greater coronal length (mean 9.9 mm vs 8.3 mm, P = .005) than distal calculi. This association was also true on the multivariate analysis, which controlled for age and sex (P = .0004). No statistically significant difference was found in the axial calculus diameter for the proximal and distal stones (mean 5.3 mm vs 5.0 mm, P = .29). In a subset of 50 patients whose contralateral ureters (without stones) were measured for control comparison, the ureteral dilation in the ureters with stones was significantly greater than in the control ureters (proximal ureter 6.2 mm vs 4.3 mm, P = .001; distal ureter 4.7 mm vs 3.8 mm, P = .004). For proximal calculi, 72.3% were associated with ureteral dilation of less than 7 mm, 23.1% with 7-10 mm, and 4.6% with greater than 10 mm. For the distal calculi, 90.1% were associated with ureteral dilation of less than 7 mm, 6.3% with 7-10 mm, and 3.6% with greater than 10 mm. The coronal length was the largest measured diameter in 94% of the calculi, and the mean calculus coronal length was significantly greater than the mean axial diameter (8.9 mm vs 5.1 mm, respectively, P < .001). The results of our study have shown that proximal ureteral calculi are associated with a significantly greater degree of ureteral dilation and larger coronal length than are distal calculi. These findings should guide the endoscopist in planning intracorporeal ureteroscopic lithotripsy. We suggest obtaining CT coronal images to more accurately characterize obstructing ureteral stones.

Bitter tasting compounds dilate airways by inhibiting airway smooth muscle calcium oscillations and calcium sensitivity

PubMed Central

Tan, Xiahui; Sanderson, Michael J

2014-01-01

Background and Purpose While selective, bitter tasting, TAS2R agonists can relax agonist-contracted airway smooth muscle (ASM), their mechanism of action is unclear. However, ASM contraction is regulated by Ca2+ signalling and Ca2+ sensitivity. We have therefore investigated how the TAS2R10 agonists chloroquine, quinine and denotonium regulate contractile agonist-induced Ca2+ signalling and sensitivity. Experimental Approach Airways in mouse lung slices were contracted with either methacholine (MCh) or 5HT and bronchodilation assessed using phase-contrast microscopy. Ca2+ signalling was measured with 2-photon fluorescence microscopy of ASM cells loaded with Oregon Green, a Ca2+-sensitive indicator (with or without caged-IP3). Effects on Ca2+ sensitivity were assessed on lung slices treated with caffeine and ryanodine to permeabilize ASM cells to Ca2+. Key Results The TAS2R10 agonists dilated airways constricted by either MCh or 5HT, accompanied by inhibition of agonist-induced Ca2+ oscillations. However, in non-contracted airways, TAS2R10 agonists, at concentrations that maximally dilated constricted airways, did not evoke Ca2+ signals in ASM cells. Ca2+ increases mediated by the photolysis of caged-IP3 were also attenuated by chloroquine, quinine and denotonium. In Ca2+-permeabilized ASM cells, the TAS2R10 agonists dilated MCh- and 5HT-constricted airways. Conclusions and Implications TAS2R10 agonists reversed bronchoconstriction by inhibiting agonist-induced Ca2+ oscillations while simultaneously reducing the Ca2+ sensitivity of ASM cells. Reduction of Ca2+ oscillations may be due to inhibition of Ca2+ release through IP3 receptors. Further characterization of bronchodilatory TAS2R agonists may lead to the development of novel therapies for the treatment of bronchoconstrictive conditions. PMID:24117140

Mates to E = mc/sup 2/ and to the Heisenberg uncertainty relations

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

Bell, A.B.; Bell, D.M.

1976-02-01

E = mc/sup 2/ is found to be a special case of E = sigma/sup +-1/c/sup n/, where sigma is any one of four susceptibilities, namely electric, magnetic, gravitational, and elastic. Let l be length, t time, ..delta..t time dilation, and ..delta..l a measure of Fitzgerald--Lorentz contraction. A particle is stated to be the manifestation of a collection of susceptibilities which arise when (..delta..l)/l = (..delta..t)/t. Then (..delta..E)/E = 5(..delta..t)/2t = +- (..delta.. sigma)/sigma. Corresponding to susceptibility, special energy particles are postulated which exhibit SU(3) symmetry. Related to the susceptibilities are five new Heisenberg uncertainty relations. Three new conservation lawsmore » for particles are proposed.« less

Novel Roles for Kv7 Channels in Shaping Histamine-Induced Contractions and Bradykinin-Dependent Relaxations in Pig Coronary Arteries

PubMed Central

Chen, Xingjuan; Li, Wennan; Hiett, S. Christopher; Obukhov, Alexander G.

2016-01-01

Voltage-gated Kv7 channels are inhibited by agonists of Gq-protein-coupled receptors, such as histamine. Recent works have provided evidence that inhibition of vascular Kv7 channels may trigger vessel contractions. In this study, we investigated how Kv7 activity modulates the histamine-induced contractions in “healthy” and metabolic syndrome (MetS) pig right coronary arteries (CAs). We performed isometric tension and immunohistochemical studies with domestic, lean Ossabaw, and MetS Ossabaw pig CAs. We found that neither the Kv7.2/Kv7.4/Kv7.5 activator ML213 nor the general Kv7 inhibitor XE991 altered the tension of CA rings under preload, indicating that vascular Kv7 channels are likely inactive in the preloaded rings. Conversely, ML213 potently dilated histamine-pre-contracted CAs, suggesting that Kv7 channels are activated during histamine applications and yet partially inhibited by histamine. Immunohistochemistry analysis revealed strong Kv7.4 immunostaining in the medial and intimal layers of the CA wall, whereas Kv7.5 immunostaining intensity was strong in the intimal but weak in the medial layers. The medial Kv7 immunostaining was significantly weaker in MetS Ossabaw CAs as compared to lean Ossabaw or domestic CAs. Consistently, histamine-pre-contracted MetS Ossabaw CAs exhibited attenuated ML213-dependent dilations. In domestic pig CAs, where medial Kv7 immunostaining intensity was stronger, histamine-induced contractions spontaneously decayed to ~31% of the peak amplitude within 4 minutes. Oppositely, in Ossabaw CAs, where Kv7 immunostaining intensity was weaker, the histamine-induced contractions were more sustained. XE991 pretreatment significantly slowed the decay rate of histamine-induced contractions in domestic CAs, supporting the hypothesis that increased Kv7 activity correlates with a faster rate of histamine-induced contraction decay. Alternatively, XE991 significantly decreased the amplitude of bradykinin-dependent dilations in pre-contracted CAs. We propose that in CAs, a decreased expression or a loss of function of Kv7 channels may lead to sustained histamine-induced contractions and reduced endothelium-dependent relaxation, both risk factors for coronary spasm. PMID:26844882

Stress and Dilatancy Relation of Methane Hydrate Bearing Sand with Various Fines Content

NASA Astrophysics Data System (ADS)

Hyodo, M.

2016-12-01

This study presents an experimental and numerical study on the shear behaviour of methane hydrate bearing sand with variable confining pressures and methane hydrate saturations. A representative grading curve of Nankai Trough is selected as the grain size distribution of host sand to artificially produce the methane hydrate bearing sand. A shear strength estimation equation for methane hydrate bearing sand from test results is established. A simple constitutive model has been proposed to predict the stress-strain response of methane hydrate bearing sand based on a few well-known relationships. Experimental results indicate that the inclination of stress-dilatancy curve becomes steeper with a rise in methane hydrate saturation. A revised stress-dilatancy equation has been integrated with this simple model to consider the variance in the inclination of stress-dilatancy curve. The mean stress Pcr at critical state when the peak stress ratio reduces to the residual stress ratio increases with the level of methane hydrate saturation. The dilatancy parameter a tends to increase with the methane hydrate saturation. The shear deformability parameter A exhibits a decreasing tendency with the rise in methane hydrate saturation at each confining pressure. This model is capable of reasonably predicting the strength and stiffness enhancement and the dilation behaviour as methane hydrate saturation increases. The volumetric variation from contraction to expansion of MH bearing sand at a lower confining pressure and only pure volumetric contraction a higher confining pressure can be represented by this simple model.

Influence of cerebral blood vessel movements on the position of perivascular synapses.

PubMed

Urrecha, Miguel; Romero, Ignacio; DeFelipe, Javier; Merchán-Pérez, Angel

2017-01-01

Synaptic activity is regulated and limited by blood flow, which is controlled by blood vessel dilation and contraction. Traditionally, the study of neurovascular coupling has mainly focused on energy consumption and oxygen delivery. However, the mechanical changes that blood vessel movements induce in the surrounding tissue have not been considered. We have modeled the mechanical changes that movements of blood vessels cause in neighboring synapses. Our simulations indicate that synaptic densities increase or decrease during vascular dilation and contraction, respectively, near the blood vessel walls. This phenomenon may alter the concentration of neurotransmitters and vasoactive substances in the immediate vicinity of the vessel wall and thus may have an influence on local blood flow.

Length adaptation of airway smooth muscle.

PubMed

Bossé, Ynuk; Sobieszek, Apolinary; Paré, Peter D; Seow, Chun Y

2008-01-01

Many types of smooth muscle, including airway smooth muscle (ASM), are capable of generating maximal force over a large length range due to length adaptation, which is a relatively rapid process in which smooth muscle regains contractility after experiencing a force decrease induced by length fluctuation. Although the underlying mechanism is unclear, it is believed that structural malleability of smooth muscle cells is essential for the adaptation to occur. The process is triggered by strain on the cell cytoskeleton that results in a series of yet undefined biochemical and biophysical events leading to restructuring of the cytoskeleton and contractile apparatus and consequently optimization of the overlap between the myosin and actin filaments. Although length adaptability is an intrinsic property of smooth muscle, maladaptation of ASM could result in excessive constriction of the airways and the inability of deep inspirations to dilate them. In this article, we describe the phenomenon of length adaptation in ASM and some possible underlying mechanisms that involve the myosin filament assembly and disassembly. We discuss a possible role of maladaptation of ASM in the pathogenesis of asthma. We believe that length adaptation in ASM is mediated by specific proteins and their posttranslational regulations involving covalent modifications, such as phosphorylation. The discovery of these molecules and the processes that regulate their activity will greatly enhance our understanding of the basic mechanisms of ASM contraction and will suggest molecular targets to alleviate asthma exacerbation related to excessive constriction of the airways.

Morphological Alterations Within the Peripheral Fixation of the Iris Dilator Muscle in Eyes With Pigmentary Glaucoma

PubMed Central

Flügel-Koch, Cassandra M.; Tektas, Ozan Y.; Kaufman, Paul L.; Paulsen, Friedrich P.; Lütjen-Drecoll, Elke

2014-01-01

Purpose. To analyze the peripheral fixation of the iris dilator muscle in normal eyes and in eyes with pigmentary glaucoma (PG). Methods. Using 63 control eyes (age 18 months–99 years), the peripheral iris dilator was investigated by light microscopy, immunohistochemistry, and electron microscopy. Development was studied using 18 differently aged fetal eyes stained immunohistochemically against α-smooth muscle (SM) actin. The peripheral iris dilator muscle in PG was analyzed using semithin and ultrathin sections of six glutaraldehyde-fixed eyes from three donors aged 38, 62, and 74 years. Results. In normal eyes, the peripheral end of the iris dilator muscle is arranged in a sphincter-like manner. Arcade-shaped tendinous connections associated with myofibroblasts (iridial strands) anchor the iris dilator within the elastic–fibromuscular ciliary meshwork that also serves as fixation area for the elastic tendons of the inner ciliary muscle portions. The iridial strands are innervated and can adapt their length during accommodation. The PG eyes show incomplete circular bundles and iridial strands that are mainly anchored to the iris stroma and the flexible uveal parts of the trabecular meshwork. Conclusions. The normal anchorage of the peripheral iris dilator and its presumably neuronally regulated length adaptation stabilize the peripheral iris during accommodation. Insufficient fixation in PG could promote posterior bowing of the iris with rubbing against the zonular fibers and pigment liberation from the iris pigmented epithelium. PMID:24938519

Smooth muscle in human bronchi is disposed to resist airway distension.

PubMed

Gazzola, Morgan; Henry, Cyndi; Couture, Christian; Marsolais, David; King, Gregory G; Fredberg, Jeffrey J; Bossé, Ynuk

2016-07-15

Studying airway smooth muscle (ASM) in conditions that emulate the in vivo environment within which the bronchi normally operate may provide important clues regarding its elusive physiological function. The present study examines the effect of lengthening and shortening of ASM on tension development in human bronchial segments. ASM from each bronchial segment was set at a length approximating in situ length (Linsitu). Bronchial tension was then measured during a slow cyclical strain (0.004Hz, from 0.7Linsitu to 1.3Linsitu) in the relaxed state and at graded levels of activation by methacholine. In all cases, tension was greater at longer ASM lengths, and greater during lengthening than shortening. The threshold of methacholine concentration that was required for ASM to account for bronchial tension across the entire range of ASM lengths tested was on average smaller by 2.8 logs during lengthening than during shortening. The length-dependency of ASM tension, together with this lower threshold of methacholine concentration during lengthening versus shortening, suggest that ASM has a greater ability to resist airway dilation during lung inflation than to narrow the airways during lung deflation. More than serving to narrow the airway, as has long been thought, these data suggest that the main function of ASM contraction is to limit airway wall distension during lung inflation. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparison of the Eder-Puestow and Celestin techniques for dilating benign oesophageal strictures.

PubMed

Hine, K R; Hawkey, C J; Atkinson, M; Holmes, G K

1984-10-01

The Celestin and Eder-Puestow methods of dilating benign oesophageal strictures have been compared prospectively in a randomised trial. One hundred and thirty three dilatations were performed on 72 patients. There was no significant difference between the two techniques with regard to the long term relief of symptoms. Celestin dilatation was quicker, less likely to cause pharyngeal trauma, and less damaging to guide wires. It could not be used, however, in those patients in whom only a short length of guide wire could be passed through the stricture.

Comparison of the Eder-Puestow and Celestin techniques for dilating benign oesophageal strictures.

PubMed Central

Hine, K R; Hawkey, C J; Atkinson, M; Holmes, G K

1984-01-01

The Celestin and Eder-Puestow methods of dilating benign oesophageal strictures have been compared prospectively in a randomised trial. One hundred and thirty three dilatations were performed on 72 patients. There was no significant difference between the two techniques with regard to the long term relief of symptoms. Celestin dilatation was quicker, less likely to cause pharyngeal trauma, and less damaging to guide wires. It could not be used, however, in those patients in whom only a short length of guide wire could be passed through the stricture. PMID:6479685

Influence of cerebral blood vessel movements on the position of perivascular synapses

PubMed Central

DeFelipe, Javier

2017-01-01

Synaptic activity is regulated and limited by blood flow, which is controlled by blood vessel dilation and contraction. Traditionally, the study of neurovascular coupling has mainly focused on energy consumption and oxygen delivery. However, the mechanical changes that blood vessel movements induce in the surrounding tissue have not been considered. We have modeled the mechanical changes that movements of blood vessels cause in neighboring synapses. Our simulations indicate that synaptic densities increase or decrease during vascular dilation and contraction, respectively, near the blood vessel walls. This phenomenon may alter the concentration of neurotransmitters and vasoactive substances in the immediate vicinity of the vessel wall and thus may have an influence on local blood flow. PMID:28199396

Cardiomyopathy mutations in the tail of β-cardiac myosin modify the coiled-coil structure and affect integration into thick filaments in muscle sarcomeres in adult cardiomyocytes.

PubMed

Wolny, Marcin; Colegrave, Melanie; Colman, Lucy; White, Ed; Knight, Peter J; Peckham, Michelle

2013-11-01

It is unclear why mutations in the filament-forming tail of myosin heavy chain (MHC) cause hypertrophic or dilated cardiomyopathy as these mutations should not directly affect contraction. To investigate this, we first investigated the impact of five hypertrophic cardiomyopathy-causing (N1327K, E1356K, R1382W, E1555K, and R1768K) and one dilated cardiomyopathy-causing (R1500W) tail mutations on their ability to incorporate into muscle sarcomeres in vivo. We used adenoviral delivery to express full-length wild type or mutant enhanced GFP-MHC in isolated adult cardiomyocytes. Three mutations (N1327K, E1356K, and E1555K) reduced enhanced GFP-MHC incorporation into muscle sarcomeres, whereas the remainder had no effect. No mutations significantly affected contraction. Fluorescence recovery after photobleaching showed that fluorescence recovery for the mutation that incorporated least well (N1327K) was significantly faster than that of WT with half-times of 25.1 ± 1.8 and 32.2 ± 2.5 min (mean ± S.E.), respectively. Next, we determined the effects of each mutation on the helical properties of wild type and seven mutant peptides (7, 11, or 15 heptads long) from the myosin tail by circular dichroism. R1382W and E1768K slightly increased the α-helical nature of peptides. The remaining mutations reduced α-helical content, with N1327K showing the greatest reduction. Only peptides containing residues 1301-1329 were highly α-helical suggesting that this region helps in initiation of coiled coil. These results suggest that small effects of mutations on helicity translate into a reduced ability to incorporate into sarcomeres, which may elicit compensatory hypertrophy.

Morphological alterations within the peripheral fixation of the iris dilator muscle in eyes with pigmentary glaucoma.

PubMed

Flügel-Koch, Cassandra M; Tektas, Ozan Y; Kaufman, Paul L; Paulsen, Friedrich P; Lütjen-Drecoll, Elke

2014-06-17

To analyze the peripheral fixation of the iris dilator muscle in normal eyes and in eyes with pigmentary glaucoma (PG). Using 63 control eyes (age 18 months-99 years), the peripheral iris dilator was investigated by light microscopy, immunohistochemistry, and electron microscopy. Development was studied using 18 differently aged fetal eyes stained immunohistochemically against α-smooth muscle (SM) actin. The peripheral iris dilator muscle in PG was analyzed using semithin and ultrathin sections of six glutaraldehyde-fixed eyes from three donors aged 38, 62, and 74 years. In normal eyes, the peripheral end of the iris dilator muscle is arranged in a sphincter-like manner. Arcade-shaped tendinous connections associated with myofibroblasts (iridial strands) anchor the iris dilator within the elastic-fibromuscular ciliary meshwork that also serves as fixation area for the elastic tendons of the inner ciliary muscle portions. The iridial strands are innervated and can adapt their length during accommodation. The PG eyes show incomplete circular bundles and iridial strands that are mainly anchored to the iris stroma and the flexible uveal parts of the trabecular meshwork. The normal anchorage of the peripheral iris dilator and its presumably neuronally regulated length adaptation stabilize the peripheral iris during accommodation. Insufficient fixation in PG could promote posterior bowing of the iris with rubbing against the zonular fibers and pigment liberation from the iris pigmented epithelium. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Ultrasonography to visualize the upper urinary tract in children with meningomyelocele.

PubMed

Abrahamsson, Kate; Jodal, Ulf; Stokland, Eira; Nordvall, Anders; Sillén, Ulla

2006-10-01

To evaluate the frequency of difficulties when using ultrasonography (US, commonly used to visualize the upper urinary tract) to evaluate renal length and dilatation in children and adolescents with meningomyelocele (MMC), who have excessive obesity or a distorted spine. The records of all children with MMC investigated during 1996-2002 were assessed retrospectively and the last investigation used for analysis. In addition to the US results, the body mass index (BMI) and angulation of the spine were recorded. Of the 160 children investigated, US was not evaluable in 46 (29%), i.e. in 35 (22%) for renal length, in one (1%) for dilatation and in 10 (6%) for both. In 99 patients with a straight spine and mild to moderate angulation, renal length was not measurable in 14 (14%), while dilatation was not evaluable in two (2%). In 61 patients with a severely angled spine, the corresponding values were 31 (51%) and nine (15%), respectively. In eight patients with a BMI of >or= 27 kg/m2 and a straight spine, four of the investigations were not completely evaluable, while six were not in the eight patients with both a BMI of >or= 27 kg/m2 and severe angulation. Both severe spinal angulation and a BMI of >or= 27 kg/m2 significantly reduced the possibility of evaluating the urinary tract by US. However, in an unselected group of children with MMC, dilatation could be evaluated in >90% and renal length in approximately 70%.

Relativistic Velocity Addition Law from Machine Gun Analogy

NASA Astrophysics Data System (ADS)

Rothenstein, Bernhard; Popescu, Stefan

2009-01-01

Many derivations of the relativistic addition law of parallel velocities without use of the Lorentz transformations (LT) are known.1-5 Some of them are based on thought experiments that require knowledge of the time dilation and the length contraction effects.1,4,5 Other derivations involve the Doppler effect in the optic domain considered from three inertial reference frames in relative motion.6 A few derivations simply involve only the principle of constancy of the light velocity.2 Such derivations are interesting for the teaching of special relativity theory since the relativistic addition of velocities leads directly to the LT.7 The derivation we propose is based on a machine gun-target analogy8 of the acoustic Doppler effect, considered from the rest frame of the machine gun and from the rest frame of the target.

Pupil diameter as predictor of cognitive load: A novel tool for geoscience education research

NASA Astrophysics Data System (ADS)

Mitra, R.; McNeal, K.

2015-12-01

Pupils can truly serve as windows to the mind. Since the early part of the last decade, pupillometry, the study of pupils in response to cognitive tasks, have gained traction in psychophysiological studies. Muscles of the iris work in tandem with the autonomic nervous system in response to light condition to either dilate or contract the pupil, usually between 2 to 7 mm. Along with this response to light conditions, the pupils also contract or dilate in response to emotional or mental response. Therefore, for a cognitive task, if the ambient brightness is controlled, pupil dilation reflects the cognitive load associated with the task. Simple tasks such as counting, memorizing, multiplying and visual searching have been found to have pupillometry profiles reflective of the cognitive load involved with such tasks. In this study, we investigate whether pupil diameter can be used for education research where tasks can be more complex. In particular, we look at two specific types of tasks common in geoscience and several other STEM fields: graph reading and spatial problem solving.

Relationship between intrapartum transperineal ultrasound measurement of angle of progression and head-perineum distance with correlation to conventional clinical parameters of labor progress and time to delivery.

PubMed

Chan, Ying Tze Viola; Ng, Vivian Kwun Sin; Yung, Wai Kuen; Lo, Tsz Kin; Leung, Wing Cheong; Lau, Wai Lam

2015-08-01

To assess whether angle of progression (AOP) and head-perineum distance (HPD) measured by intrapartum transperineal ultrasound (ITU) correlate with clinical fetal head station (station); and whether AOP versus HPD varies during uterine contraction and relaxation. In a subset of primiparous women, whether these ITU parameters correlate with time to normal spontaneous delivery (TD). We evaluated prospectively 100 primiparous and multiparous women at term in active labor. Transabdominal and transperineal ultrasound (sagittal and transverse plane) were used to measure fetal head position and ITU parameters, respectively. Digitally palpated station and cervical dilatation were also noted. The results were compared using regression and correlation coefficients. Station was moderately correlated with AOP (r = 0.579) and HPD (r = -0.497). AOP was highly correlated with HPD during uterine contraction (r = -0.703) and relaxation (r = -0.647). In the subgroup of primiparous women, natural log of TD has the highest correlation with HPD and AOP during uterine contraction (r = 0.742), making prediction of TD similar to that of using cervical dilatation. ITU parameters were moderately correlated with station. There was constant high correlation between AOP and HPD. Prediction of TD in primiparous women using ITU parameters was similar to that of using cervical dilatation.

History-dependence of muscle slack length following contraction and stretch in the human vastus lateralis.

PubMed

Stubbs, Peter W; Walsh, Lee D; D'Souza, Arkiev; Héroux, Martin E; Bolsterlee, Bart; Gandevia, Simon C; Herbert, Robert D

2018-06-01

In reduced muscle preparations, the slack length and passive stiffness of muscle fibres have been shown to be influenced by previous muscle contraction or stretch. In human muscles, such behaviours have been inferred from measures of muscle force, joint stiffness and reflex magnitudes and latencies. Using ultrasound imaging, we directly observed that isometric contraction of the vastus lateralis muscle at short lengths reduces the slack lengths of the muscle-tendon unit and muscle fascicles. The effect is apparent 60 s after the contraction. These observations imply that muscle contraction at short lengths causes the formation of bonds which reduce the effective length of structures that generate passive tension in muscles. In reduced muscle preparations, stretch and muscle contraction change the properties of relaxed muscle fibres. In humans, effects of stretch and contraction on properties of relaxed muscles have been inferred from measurements of time taken to develop force, joint stiffness and reflex latencies. The current study used ultrasound imaging to directly observe the effects of stretch and contraction on muscle-tendon slack length and fascicle slack length of the human vastus lateralis muscle in vivo. The muscle was conditioned by (a) strong isometric contractions at long muscle-tendon lengths, (b) strong isometric contractions at short muscle-tendon lengths, (c) weak isometric contractions at long muscle-tendon lengths and (d) slow stretches. One minute after conditioning, ultrasound images were acquired from the relaxed muscle as it was slowly lengthened through its physiological range. The ultrasound image sequences were used to identify muscle-tendon slack angles and fascicle slack lengths. Contraction at short muscle-tendon lengths caused a mean 13.5 degree (95% CI 11.8-15.0 degree) shift in the muscle-tendon slack angle towards shorter muscle-tendon lengths, and a mean 5 mm (95% CI 2-8 mm) reduction in fascicle slack length, compared to the other conditions. A supplementary experiment showed the effect could be demonstrated if the muscle was conditioned by contraction at short lengths but not if the relaxed muscle was held at short lengths, confirming the role of muscle contraction. These observations imply that muscle contraction at short lengths causes the formation of bonds which reduce the effective length of structures that generate passive tension in muscles. © 2018 The Authors. The Journal of Physiology © 2018 The Physiological Society.

Relationship between dilatancy, stresses and plastic dissipation in a granular material with rigid grains

NASA Astrophysics Data System (ADS)

Evesque, Pierre; Stefani, Christian

1991-11-01

By considering a drained cohesionless granular sample made up of rigid grains and submitted to a triaxial test, we derive an equation relating the dilatancy K, the deviatoric stress q and the confining pressure p to the energy losses D_plastic due to plastic yielding. We demonstrate that the system is contracting (K le 0) at q = 0, when q is increasing and that spontaneous uncontrolled yielding begins occurring when dilatancy K is maximum. We also demonstrate the existence of the characteristic state introduced by Luong and Habib and the existence of the critical state of Schofield and Wroth. Finally, we give a method to determine the plastic losses during a triaxial cell test using the experimental data. En utilisant un postulat de reproductibilité des essais triaxiaux et une relation liant l'énergie dissipée, la dilatance K et les contraintes imposées à un échantillon, on démontre qu'un matériau granulaire ne peut que se contracter après avoir subi une contrainte de confinement isotrope (i.e. q = 0), que la rupture spontanée a lieu après un maximum de dilatance, qu'il existe un état caractéristique (au sens de Luong et Habib) et qu'il existe un état “ critique ” (au sens de Schofield et Wroth). Nous donnons de plus une méthode pour estimer la dissipation-plastique durant un essai triaxial à partir des résultats expérimentaux.

Electromyographic activity of the hyoepiglotticus muscle and control of epiglottis position in horses.

PubMed

Holcombe, Susan J; Cornelisse, Cornelis J; Berney, Cathy; Robinson, N Edward

2002-12-01

To determine whether the hyoepiglotticus muscle has respiratory-related electromyographic activity and whether electrical stimulation of this muscle changes the position and conformation of the epiglottis, thereby altering dimensions of the aditus laryngis. 6 Standardbred horses. Horses were anesthetized, and a bipolar fine-wire electrode was placed in the hyoepiglotticus muscle of each horse. Endoscopic images of the nasopharynx and larynx were recorded during electrical stimulation of the hyoepiglotticus muscle in standing, unsedated horses. Dorsoventral length and area of the aditus laryngis were measured on images obtained before and during electrical stimulation. Electromyographic activity of the hyoepiglotticus muscle and nasopharyngeal pressures were measured while horses exercised on a treadmill at 50, 75, 90, and 100% of the speed that produced maximum heart rate. Electrical stimulation of the hyoepiglotticus muscle changed the shape of the epiglottis, displaced it ventrally, and significantly increased the dorsoventral length and area of the aditus laryngis. The hyoepiglotticus muscle had inspiratory activity that increased significantly with treadmill speed as a result of an increase in phasic and tonic activity. Expiratory activity of the hyoepiglotticus muscle did not change with treadmill speed in 4 of 6 horses. Findings reported here suggest that contraction of the hyoepiglotticus muscle increases dimensions of the airway in horses by depressing the epiglottis ventrally during intense breathing efforts. The hyoepiglotticus muscle may be an important muscle for dilating the airway in horses, and contraction of the hyoepiglotticus muscle may induce conformational changes in the epiglottis.

Regulation of landslide motion by dilatancy and pore pressure feedback

USGS Publications Warehouse

Iverson, R.M.

2005-01-01

A new mathematical model clarifies how diverse styles and rates of landslide motion can result from regulation of Coulomb friction by dilation or contraction of water-saturated basal shear zones. Normalization of the model equations shows that feedback due to coupling between landslide motion, shear zone volume change, and pore pressure change depends on a single dimensionless parameter ??, which, in turn, depends on the dilatancy angle ?? and the intrinsic timescales for pore pressure generation and dissipation. If shear zone soil contracts during slope failure, then ?? 0, and negative feedback permits slow, steady landslide motion to occur while positive pore pressure is supplied by rain infiltration. Steady state slip velocities v0 obey v0 = -(K/??) p*e, where K is the hydraulic conductivity and p*e is the normalized (dimensionless) negative pore pressure generated by dilation. If rain infiltration and attendant pore pressure growth continue unabated, however, their influence ultimately overwhelms the stabilizing influence of negative p*e. Then, unbounded landslide acceleration occurs, accentuated by an instability that develops if ?? diminishes as landslide motion proceeds. Nonetheless, numerical solutions of the model equations show that slow, nearly steady motion of a clay-rich landslide may persist for many months as a result of negative pore pressure feedback that regulates basal Coulomb friction. Similarly stabilized motion is less likely to occur in sand-rich landslides that are characterized by weaker negative feedback.

Special Relativity in Week One: 3) Introducing the Lorentz Contraction

ERIC Educational Resources Information Center

Huggins, Elisha

2011-01-01

This is the third of four articles on teaching special relativity in the first week of an introductory physics course. With Einstein's second postulate that the speed of light is the same to all observers, we could use the light pulse clock to introduce time dilation. But we had difficulty introducing the Lorentz contraction until we saw the movie…

Factors associated with complications or failure of endoscopic balloon dilation of anastomotic stricture secondary to Roux-en-Y gastric bypass surgery.

PubMed

de Moura, Eduardo G H; Orso, Ivan R B; Aurélio, Eduardo F; de Moura, Eduardo T H; de Moura, Diogo T H; Santo, Marco A

2016-01-01

Roux-en-Y gastric bypass is a commonly used technique of bariatric surgery. One of the most important complications is gastrojejunal anastomotic stricture. Endoscopic balloon dilation appears to be well tolerated and effective, but well-designed randomized, controlled trials have not yet been conducted. Identify factors associated with complications or failure of endoscopic balloon dilation of anastomotic stricture secondary to Roux-en-Y gastric bypass surgery. Gastrointestinal endoscopy service, university hospital, Brazil. The records of 64 patients with anastomotic stricture submitted to endoscopic dilation with hydrostatic balloon dilation were reviewed. Information was collected on gastric pouch length, anastomosis diameter before dilation, number of dilation sessions, balloon diameter at each session, anastomosis diameter after the last dilation session, presence of postsurgical complications, endoscopic complications, and outcome of dilation. Comparisons were made among postsurgical and endoscopic complications; number of dilations, balloon diameter; anastomosis diameter before dilation; and dilation outcome. Success of dilation treatment was 95%. Perforation was positively and significantly associated with the number of dilation sessions (P = .03). Highly significant associations were found between ischemic segment and perforation (P<.001) and between ischemic segment and bleeding (P = .047). Ischemic segment (P = .02) and fistula (P = .032) were also associated with dilation failure. Ischemic segment and fistula were found to be important risk factors for balloon dilation failure. The greater the number of dilation sessions, the greater the number of endoscopic complications. Copyright © 2016 American Society for Metabolic and Bariatric Surgery. Published by Elsevier Inc. All rights reserved.

Topical Mitomycin C application in the treatment of refractory benign esophageal strictures in adults and comprehensive literature review.

PubMed

Bartel, Michael J; Seeger, Kristina; Jeffers, Kayin; Clayton, Donnesha; Wallace, Michael B; Raimondo, Massimo; Woodward, Timothy A

2016-09-01

Recurrent complex esophageal strictures remain difficult to manage. To determine the efficacy of topical Mitomycin C application for recurrent benign esophageal strictures. All patients who underwent balloon dilation followed by topical Mitomycin C application for recurrent benign esophageal strictures were included. Primary outcome was number of dilations and change of dysphagia score. Nine patients with anastomotic (3), radiation-induced (3), caustic (2), and combined anastomotic and radiation-induced (1) strictures were included. Strictures had a mean length of 13.75mm, diameter of 8.0mm, and were dilated 10.7 times over a median of 8 months (1.5 dilations per month). Following Mitomycin C application, the need for further dilation decreased to 0.39 dilations per month over a median of 10 months; however, dysphagia scores improved not significantly from 3.2 to 2.6 (mean). In this pilot study, topical Mitomycin C in conjunction with dilation decreased the frequency of esophageal dilations for recurrent benign esophageal strictures. Copyright © 2016 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

The length of pre-existing fissures effects on the mechanical properties of cracked red sandstone and strength design in engineering.

PubMed

Wu, Jiangyu; Feng, Meimei; Yu, Bangyong; Han, Guansheng

2018-01-01

It is important to study the mechanical properties of cracked rock to understand the engineering behavior of cracked rock mass. Consequently, the influence of the length of pre-existing fissures on the strength, deformation, acoustic emission (AE) and failure characteristics of cracked rock specimen was analyzed, and the optimal selection of strength parameter in engineering design was discussed. The results show that the strength parameters (stress of dilatancy onset and uniaxial compressive strength) and deformation parameters (axial strain and circumferential strain at dilatancy onset and peak point) of cracked rock specimen decrease with the increase of the number of pre-existing fissures, and the relations which can use the negative exponential function to fit. Compared with the intact rock specimens, the different degrees of stress drop phenomena were produced in the process of cracked rock specimens when the stress exceeds the dilatancy onset. At this moment, the cracked rock specimens with the existence of stress drop are not instantaneous failure, but the circumferential strain, volumetric strain and AE signals increase burstingly. And the yield platform was presented in the cracked rock specimen with the length of pre-existing fissure more than 23mm, the yield failure was gradually conducted around the inner tip of pre-existing fissure, the development of original fissures and new cracks was evolved fully in rock. However, the time of dilatancy onset is always ahead of the the time of that point with the existence of stress drop. It indicates that the stress of dilatancy onset can be as the parameter of strength design in rock engineering, which can effectively prevent the large deformation of rock. Copyright © 2017 Elsevier B.V. All rights reserved.

[Technical feasibility of the implantation of a monorail stent system into the renal arteries without pre-dilatation].

PubMed

Neumann, C; Gschwendtner, M; Karnel, F; Mair, J; Dorffner, G; Dorffner, R

2005-01-01

To evaluate the technical feasibility of the implantation of the monorail RX Herculink system into the renal arteries without pre-dilatation. Forty-two patients (mean age 71 years) from four centers with a total of 44 renal artery stenoses underwent implantation of the RX Herculink stent. The mean grade of the stenosis was 83.8 %, the mean length 7.5 mm. The stenoses were ostial in 38 cases and in immediate proximity to the ostium in 6 cases. The mean follow-up-period was 57 weeks (24 - 176 weeks). In 42 cases, the implantation was successful without pre-dilatation. In 2 cases, pre-dilatation was carried out. In none of the cases, detachment of the stent from the balloon was observed. In one stenosis with a length of 17 mm, implantation of two stents was performed. In 9 cases, post-dilatation with a larger balloon or higher balloon pressure was necessary. Residual stenoses exceeding 30 % were not observed. Two patients developed local bleeding at the puncture site. During the follow-up, restenoses were observed in 5 stents after 26 to 126 weeks, which necessitated a second intervention in 3 cases (PTA in 2 cases, re-stenting in 1 case). The primary patency rate after 6 and 12 months was 0.92 +/- 0.056 according to Kaplan-Meier, the secondary patency rate after 6 and 12 months was 1.0 +/- 0.0. Implantation of the RX Herculink stent system into the renal arteries without pre-dilatation is technically feasible and safe. Even without pre-dilatation, the stent-system can be advanced through the stenosis without detachment. The complication rate is low. Our clinical results are comparable to previous studies.

30 CFR 206.110 - How do I determine a transportation allowance under an arm's-length transportation contract?

Code of Federal Regulations, 2010 CFR

2010-07-01

... under an arm's-length transportation contract? 206.110 Section 206.110 Mineral Resources MINERALS... § 206.110 How do I determine a transportation allowance under an arm's-length transportation contract? (a) If you or your affiliate incur transportation costs under an arm's-length transportation contract...

30 CFR 206.103 - How do I value oil that is not sold under an arm's-length contract?

Code of Federal Regulations, 2010 CFR

2010-07-01

... arm's-length contract? 206.103 Section 206.103 Mineral Resources MINERALS MANAGEMENT SERVICE... oil that is not sold under an arm's-length contract? This section explains how to value oil that you... average of the gross proceeds accruing to the seller under your or your affiliates' arm's-length contracts...

Actin protofilament orientation in deformation of the erythrocyte membrane skeleton.

PubMed Central

Picart, C; Dalhaimer, P; Discher, D E

2000-01-01

The red cell's spectrin-actin network is known to sustain local states of shear, dilation, and condensation, and yet the short actin filaments are found to maintain membrane-tangent and near-random azimuthal orientations. When calibrated with polarization results for single actin filaments, imaging of micropipette-deformed red cell ghosts has allowed an assessment of actin orientations and possible reorientations in the network. At the hemispherical cap of the aspirated projection, where the network can be dilated severalfold, filaments have the same membrane-tangent orientation as on a relatively unstrained portion of membrane. Likewise, over the length of the network projection pulled into the micropipette, where the network is strongly sheared in axial extension and circumferential contraction, actin maintains its tangent orientation and is only very weakly aligned with network extension. Similar results are found for the integral membrane protein Band 3. Allowing for thermal fluctuations, we deduce a bound for the effective coupling constant, alpha, between network shear and azimuthal orientation of the protofilament. The finding that alpha must be about an order of magnitude or more below its tight-coupling value illustrates how nanostructural kinematics can decouple from more macroscopic responses. Monte Carlo simulations of spectrin-actin networks at approximately 10-nm resolution further support this conclusion and substantiate an image of protofilaments as elements of a high-temperature spin glass. PMID:11106606

Evidence against vasoactive intestinal polypeptide (VIP) as a dilator and in favour of substance P as a constrictor in airway neurogenic responses.

PubMed

Karlsson, J A; Persson, C G

1983-07-01

Propranolol-resistant neurogenic relaxation persisted in (carbachol-contracted) guinea-pig tracheae already relaxed by supramaximal concentrations of vasoactive intestinal polypeptide (VIP). Also, VIP relaxed preparations that were under neurogenic inhibition. In hilus bronchi, about 60% of a neurogenic contraction was atropine-resistant. (Arg5, D-Trp7.9) SP 5-11 specifically antagonized this contraction and those produced by exogenous substance P. Substance P, but not VIP, seems to be involved in nerve-mediated effects on guinea-pig airway tone.

30 CFR 1206.103 - How do I value oil that is not sold under an arm's-length contract?

Code of Federal Regulations, 2011 CFR

2011-07-01

... arm's-length contract? 1206.103 Section 1206.103 Mineral Resources OFFICE OF SURFACE MINING... Oil § 1206.103 How do I value oil that is not sold under an arm's-length contract? This section... affiliates' arm's-length contracts for the purchase or sale of production from the field or area during the...

Contribution of Different Anatomical and Physiologic Factors to Iris Contour and Anterior Chamber Angle Changes During Pupil Dilation: Theoretical Analysis

PubMed Central

Jouzdani, Sara; Amini, Rouzbeh; Barocas, Victor H.

2013-01-01

Purpose. To investigate the contribution of three anatomical and physiologic factors (dilator thickness, dynamic pupillary block, and iris compressibility) to changes in iris configuration and anterior chamber angle during pupil dilation. Methods. A mathematical model of the anterior segment based on the average values of ocular dimensions was developed to simulate pupil dilation. To change the pupil diameter from 3.0 to 5.4 mm in 10 seconds, active dilator contraction was applied by imposing stress in the dilator region. Three sets of parameters were varied in the simulations: (1) a thin (4 μm, 1% of full thickness) versus a thick dilator (covering the full thickness iris) to quantify the effects of dilator anatomy, (2) in the presence (+PB) versus absence of pupillary block (−PB) to quantify the effect of dynamic motion of aqueous humor from the posterior to the anterior chamber, and (3) a compressible versus an incompressible iris to quantify the effects of iris volume change. Changes in the apparent iris–lens contact and angle open distance (AOD500) were calculated for each case. Results. The thin case predicted a significant increase (average 700%) in iris curvature compared with the thick case (average 70%), showing that the anatomy of dilator plays an important role in iris deformation during dilation. In the presence of pupillary block (+PB), AOD500 decreased 25% and 36% for the compressible and incompressible iris, respectively. Conclusions. Iris bowing during dilation was driven primarily by posterior location of the dilator muscle and by dynamic pupillary block, but the effect of pupillary block was not as large as that of the dilator anatomy according to the quantified values of AOD500. Incompressibility of the iris, in contrast, had a relatively small effect on iris curvature but a large effect on AOD500; thus, we conclude that all three effects are important. PMID:23482467

Infertility associated with persistent hymen in an alpaca and a llama

PubMed Central

Tan, Rachel H.H.; Dascanio, John J.

2008-01-01

Perforation and dilation of the persistent hymen in an alpaca and a llama, detected by vaginal examination and endoscopy, was achieved by use of a sigmoidoscope and incremental dilation using cylindrical instruments to a maximum diameter of 38 mm. Outcome and subsequent fertility are dependent on length of time the obstruction has been present and secondary uterine disease. PMID:19183735

30 CFR 1206.111 - How do I determine a transportation allowance if I do not have an arm's-length transportation...

Code of Federal Regulations, 2014 CFR

2014-07-01

... if I do not have an arm's-length transportation contract or arm's-length tariff? 1206.111 Section... I do not have an arm's-length transportation contract or arm's-length tariff? (a) This section applies if you or your affiliate do not have an arm's-length transportation contract, including situations...

30 CFR 1206.111 - How do I determine a transportation allowance if I do not have an arm's-length transportation...

Code of Federal Regulations, 2012 CFR

2012-07-01

... if I do not have an arm's-length transportation contract or arm's-length tariff? 1206.111 Section... I do not have an arm's-length transportation contract or arm's-length tariff? (a) This section applies if you or your affiliate do not have an arm's-length transportation contract, including situations...

30 CFR 1206.111 - How do I determine a transportation allowance if I do not have an arm's-length transportation...

Code of Federal Regulations, 2013 CFR

2013-07-01

... if I do not have an arm's-length transportation contract or arm's-length tariff? 1206.111 Section... I do not have an arm's-length transportation contract or arm's-length tariff? (a) This section applies if you or your affiliate do not have an arm's-length transportation contract, including situations...

30 CFR 1206.111 - How do I determine a transportation allowance if I do not have an arm's-length transportation...

Code of Federal Regulations, 2011 CFR

2011-07-01

... if I do not have an arm's-length transportation contract or arm's-length tariff? 1206.111 Section... transportation allowance if I do not have an arm's-length transportation contract or arm's-length tariff? (a) This section applies if you or your affiliate do not have an arm's-length transportation contract...

Length Contraction Should not be Independent of Time

NASA Astrophysics Data System (ADS)

Smarandache, Florentin

2013-10-01

In Special Theory of Relativity it looks that the length contraction along the direction of the motion is independent of time, i.e. if a rocket flies one second, or the rocket flies one year the rocket's along-the-motion length contraction is the same, since the contraction factor C (v) =√{ 1 -v2/c2 } depends on the rocket's relativistic speed (v) and on the light speed in vacuum (c) only. We find this as unrealistic, incomplete. It is logical that flying more and more it should increase the length contraction. What about the cosmic bodies that continuously travel, do they contract only once or are they continuously contracting?

Comparative study of labour induced by oral prostaglandin E2 and intravenous syntocinon.

PubMed

Murray, C P; Clinch, J

1975-03-22

The use of prostaglandin E2 for the induction of labor with intact membranes is described and its effectiveness is compared to intravenous syntocinon. 40 primigravida and 60 multigravid patients with previous medical and obstetrical histories were studied. The patients were numbered as they entered the trial, with the odd numbers in each group being given oral prostaglandin and the even numbers intravenous syntocinon. In no case was the pregnancy less than 38 weeks maturity. No patient was in labor prior to being given either drug. Prostaglandin E2 (PGE2) was supplied in ampoules containing 5 milligrams in 0.5 milliliter of ethanol. This was added to 49.5 milliliters of sterile water to produce a concentration of the drug of 0.1 milligrams per ml. The syntocinon infusion was prepared by putting 20 units of syntocinon into 1 liter of 5% dextrose in water to produce a solution concentration of 20 mu/ml. The accepted criteria for diagnosing established labor for both groups of patients was the presence of uterine contractions occurring once every 3 minutes, associated with progressive dilatation of the cervix. For both groups of patients it was decided that cervical dilatation should be at least 6 cm within 18 hours of the infusion starting. Using this criterion there was only 1 failure, occurring in the 1st primigravid patient given PGE2, the labor in this instance being completed with intravenous syntocinon. A further 8 patients failed to complete the trial as they had to be delivered by cesarian section. Syntocin was considerably more efficient than PGE2 in inducing labor in the remaining 91 patients particularly in primigravida. This was the case whether judged by the length of labor or by the induction delivery interval. Toco-dynamometric studies showed that the contractions produced by prostaglandin more closely resembled those of normal labor and were less painful.

Endoscopic management of esophageal stenosis in children: New and traditional treatments.

PubMed

Dall'Oglio, Luigi; Caldaro, Tamara; Foschia, Francesca; Faraci, Simona; Federici di Abriola, Giovanni; Rea, Francesca; Romeo, Erminia; Torroni, Filippo; Angelino, Giulia; De Angelis, Paola

2016-02-25

Post-esophageal atresia anastomotic strictures and post-corrosive esophagitis are the most frequent types of cicatricial esophageal stricture. Congenital esophageal stenosis has been reported to be a rare but typical disease in children; other pediatric conditions are peptic, eosinophilic esophagitis and dystrophic recessive epidermolysis bullosa strictures. The conservative treatment of esophageal stenosis and strictures (ES) rather than surgery is a well-known strategy for children. Before planning esophageal dilation, the esophageal morphology should be assessed in detail for its length, aspect, number and level, and different conservative strategies should be chosen accordingly. Endoscopic dilators and techniques that involve different adjuvant treatment strategies have been reported and depend on the stricture's etiology, the availability of different tools and the operator's experience and preferences. Balloon and semirigid dilators are the most frequently used tools. No high-quality studies have reported on the differences in the efficacies and rates of complications associated with these two types of dilators. There is no consensus in the literature regarding the frequency of dilations or the diameter that should be achieved. The use of adjuvant treatments has been reported in cases of recalcitrant stenosis or strictures with evidence of dysphagic symptoms. Corticosteroids (either systemically or locally injected), the local application of mitomycin C, diathermy and laser ES sectioning have been reported. Some authors have suggested that stenting can reduce both the number of dilations and the treatment length. In many cases, this strategy is effective when either metallic or plastic stents are utilized. Treatment complications, such esophageal perforations, can be conservatively managed, considering surgery only in cases with severe pleural cavity involvement. In cases of stricture relapse, even if such relapses occur following the execution of well-conducted conservative strategies, surgical stricture resection and anastomosis or esophageal substitution are the only remaining options.

30 CFR 1206.110 - How do I determine a transportation allowance under an arm's-length transportation contract?

Code of Federal Regulations, 2013 CFR

2013-07-01

... under an arm's-length transportation contract? 1206.110 Section 1206.110 Mineral Resources OFFICE OF... Oil § 1206.110 How do I determine a transportation allowance under an arm's-length transportation contract? (a) If you or your affiliate incur transportation costs under an arm's-length transportation...

30 CFR 1206.110 - How do I determine a transportation allowance under an arm's-length transportation contract?

Code of Federal Regulations, 2014 CFR

2014-07-01

... under an arm's-length transportation contract? 1206.110 Section 1206.110 Mineral Resources OFFICE OF... Oil § 1206.110 How do I determine a transportation allowance under an arm's-length transportation contract? (a) If you or your affiliate incur transportation costs under an arm's-length transportation...

30 CFR 1206.110 - How do I determine a transportation allowance under an arm's-length transportation contract?

Code of Federal Regulations, 2012 CFR

2012-07-01

... under an arm's-length transportation contract? 1206.110 Section 1206.110 Mineral Resources OFFICE OF... Oil § 1206.110 How do I determine a transportation allowance under an arm's-length transportation contract? (a) If you or your affiliate incur transportation costs under an arm's-length transportation...

Evidence against vasoactive intestinal polypeptide (VIP) as a dilator and in favour of substance P as a constrictor in airway neurogenic responses.

PubMed Central

Karlsson, J. A.; Persson, C. G.

1983-01-01

Propranolol-resistant neurogenic relaxation persisted in (carbachol-contracted) guinea-pig tracheae already relaxed by supramaximal concentrations of vasoactive intestinal polypeptide (VIP). Also, VIP relaxed preparations that were under neurogenic inhibition. In hilus bronchi, about 60% of a neurogenic contraction was atropine-resistant. (Arg5, D-Trp7.9) SP 5-11 specifically antagonized this contraction and those produced by exogenous substance P. Substance P, but not VIP, seems to be involved in nerve-mediated effects on guinea-pig airway tone. PMID:6197124

H1- and H2-receptor characterization in the tracheal circulation of sheep.

PubMed Central

Webber, S. E.; Salonen, R. O.; Widdicombe, J. G.

1988-01-01

1. The effects of histamine, the specific H1-agonist SKF 71481-A2 and the H2-agonist dimaprit were examined on tracheal vascular resistance in sheep anaesthetized with pentobarbitone. Tracheal vascular resistance was determined by perfusing the cranial tracheal arteries at constant flows and measuring inflow pressures. Changes in tracheal smooth muscle tone were also measured. 2. Histamine and SKF 71481-A2 contracted the tracheal smooth muscle and this effect was blocked by the H1-antagonist mepyramine. Stimulation of H2-receptors with dimaprit had no effect on tracheal smooth muscle tone. 3. Histamine had a complex action on the tracheal vasculature producing either a triphasic change (early dilatation then constriction followed by late dilatation) or just a constriction. SKF 71481-A2 always produced a biphasic change in vascular resistance (dilatation followed by constriction). Dimaprit dilated the tracheal vasculature. 4. The late dilatation produced by histamine in some sheep was blocked by bilateral cervical vagotomy but the mechanism for this effect is not known. No other responses to histamine, SKF 71481-A2 or dimaprit were affected by vagotomy. 5. The vasoconstriction produced by histamine and SKF 71481-A2 was antagonized by mepyramine indicating a H1-receptor-mediated effect. Cimetidine had no effect on the vasoconstriction to histamine suggesting a lack of involvement of H2-receptors. 6. The vasodilatation produced by histamine and SKF 71481-A2 was also antagonized by mepyramine, again suggesting a H1-receptor-mediated action. Cimetidine had no effect on the vasodilator response to histamine indicating no involvement of H2-receptors in this response. 7. The dilator effect of dimaprit was antagonized by cimetidine suggesting this effect was mediated by H2-receptors. 8. We conclude that H1-receptors in the various parts of the sheep tracheal vasculature can cause increases and decreases in total tracheal vascular resistance; that H2-receptors decrease resistance; and that the tracheal smooth muscle contracts on activation of H1-receptors but has no response to H2-agonists. PMID:2906559

Stalk-length-dependence of the contractility of Vorticella convallaria

NASA Astrophysics Data System (ADS)

Gul Chung, Eun; Ryu, Sangjin

2017-12-01

Vorticella convallaria is a sessile protozoan of which the spasmoneme contracts on a millisecond timescale. Because this contraction is induced and powered by the binding of calcium ions (Ca2+), the spasmoneme showcases Ca2+-powered cellular motility. Because the isometric tension of V. convallaria increases linearly with its stalk length, it is hypothesized that the contractility of V. convallaria during unhindered contraction depends on the stalk length. In this study, the contractile force and energetics of V. convallaria cells of different stalk lengths were evaluated using a fluid dynamic drag model which accounts for the unsteadiness and finite Reynolds number of the water flow caused by contracting V. convallaria and the wall effect of the no-slip substrate. It was found that the contraction displacement, peak contraction speed, peak contractile force, total mechanical work, and peak power depended on the stalk length. The observed stalk-length-dependencies were simulated using a damped spring model, and the model estimated that the average spring constant of the contracting stalk was 1.34 nN µm-1. These observed length-dependencies of Vorticella’s key contractility parameters reflect the biophysical mechanism of the spasmonemal contraction, and thus they should be considered in developing a theoretical model of the Vorticella spasmoneme.

Pharmacologic and Nonpharmacologic Approaches to the Treatment of Hypertension with Implications for the Clinical Nurse Specialist

DTIC Science & Technology

1988-01-01

Hypertension 6 14 that assist in regulation of smooth muscle contraction . This results in a lowered peripheral vascular resistance and 6 thus, a lowering of...the effect of epinephrine and also allows the sustained vascular smooth - muscle contraction caused by the catecholamines; this too, contributing to an...hypertension. These agents cause arteriolar dilatation by acting directly on vascular smooth muscle . They do this by interfering with the calcium gates

30 CFR 1206.110 - How do I determine a transportation allowance under an arm's-length transportation contract?

Code of Federal Regulations, 2011 CFR

2011-07-01

... under an arm's-length transportation contract? 1206.110 Section 1206.110 Mineral Resources OFFICE OF... VALUATION Federal Oil § 1206.110 How do I determine a transportation allowance under an arm's-length transportation contract? (a) If you or your affiliate incur transportation costs under an arm's-length...

Mechanisms underlying capsaicin effects in canine coronary artery: implications for coronary spasm

PubMed Central

Hiett, S. Christopher; Owen, Meredith K.; Li, Wennan; Chen, Xingjuan; Riley, Ashley; Noblet, Jillian; Flores, Sarah; Sturek, Michael; Tune, Johnathan D.; Obukhov, Alexander G.

2014-01-01

Aims The TRPV1, transient receptor potential vanilloid type 1, agonist capsaicin is considered to be beneficial for cardiovascular health because it dilates coronary arteries through an endothelial-dependent mechanism and may slow atheroma progression. However, recent reports indicate that high doses of capsaicin may constrict coronary arterioles and even provoke myocardial infarction. Thus far, the mechanisms by which TRPV1 activation modulates coronary vascular tone remain poorly understood. This investigation examined whether there is a synergistic interplay between locally acting vasoconstrictive pro-inflammatory hormones (autacoids) and capsaicin effects in the coronary circulation. Methods and results Experiments were performed in canine conduit coronary artery rings and isolated smooth muscle cells (CASMCs). Isometric tension measurements revealed that 1–10 μM capsaicin alone did not affect resting tension of coronary artery rings. In contrast, in endothelium-intact rings pre-contracted with a Gq/11-coupled FP/TP (prostaglandin F/thromboxane) receptor agonist, prostaglandin F2α (PGF2α; 10 μM), capsaicin first induced transient dilation that was followed by sustained contraction. In endothelium-denuded rings pre-contracted with PGF2α or thromboxane analogue U46619 (1 μM, a TP receptor agonist), capsaicin induced only sustained contraction. Blockers of the TP receptor or TRPV1 significantly inhibited capsaicin effects, but these were still observed in the presence of 50 μM nifedipine and 70 mM KCl. Capsaicin also potentiated 20 mM KCl-induced contractions. Fluorescence imaging experiments in CASMCs revealed that the Gq/11-phospholipase C (PLC)-protein kinase C (PKC) and Ca2+-PLC-PKC pathways are likely involved in sensitizing CASMC TRPV1 channels. Conclusion Capsaicin alone does not cause contractions in conduit canine coronary artery; however, pre-treatment with pro-inflammatory prostaglandin–thromboxane agonists may unmask capsaicin's vasoconstrictive potential. PMID:24935430

30 CFR 1206.103 - How do I value oil that is not sold under an arm's-length contract?

Code of Federal Regulations, 2012 CFR

2012-07-01

... arm's-length contract? 1206.103 Section 1206.103 Mineral Resources OFFICE OF NATURAL RESOURCES REVENUE... oil that is not sold under an arm's-length contract? This section explains how to value oil that you...-weighted average of the gross proceeds accruing to the seller under your or your affiliates' arm's-length...

30 CFR 1206.103 - How do I value oil that is not sold under an arm's-length contract?

Code of Federal Regulations, 2013 CFR

2013-07-01

... arm's-length contract? 1206.103 Section 1206.103 Mineral Resources OFFICE OF NATURAL RESOURCES REVENUE... oil that is not sold under an arm's-length contract? This section explains how to value oil that you...-weighted average of the gross proceeds accruing to the seller under your or your affiliates' arm's-length...

30 CFR 1206.103 - How do I value oil that is not sold under an arm's-length contract?

Code of Federal Regulations, 2014 CFR

2014-07-01

... arm's-length contract? 1206.103 Section 1206.103 Mineral Resources OFFICE OF NATURAL RESOURCES REVENUE... oil that is not sold under an arm's-length contract? This section explains how to value oil that you...-weighted average of the gross proceeds accruing to the seller under your or your affiliates' arm's-length...

Toward a Rethinking of the Relativity Revolution

NASA Astrophysics Data System (ADS)

Siegel, Daniel

2014-03-01

This journey in the history of physics is offered in celebration of David Cassidy's Pais Prize. The journey, undertaken in part with the community of historians of physics and in part not, starts from a conventional characterization of the relativity revolution as an abrupt transition, in 1905, from pre-Einsteinian darkness to Einsteinian light, and ends with an alternative perspective on the relativity revolution, seeing it as a process extending over 50 years, in two phases: first, the protorelativity phase, lasting from the early 1880s to 1905, and involving initial treatments of the length contraction, the mass increase, and invariance properties; second, the Einsteinian phase, beginning with his recasting of the basic theoretical framework--with the inclusion now of the time dilation and the E = mc2 relationship--and continuing with the ensuing competition between the protorelativistic and Einsteinian approaches, issuing in the final triumph of the Einsteinian approach only in the early 1930s. A proper appreciation of the character and importance of the protorelativity phase of the relativity revolution is relevant to a variety of contexts: for the teaching of relativity theory, it makes available a more concrete and pictorial approach to the relativistic effects--retaining greater (length contraction) or somewhat lesser (mass increase) validity to the present day; for the ongoing discourse on the nature of scientific revolutions, it provides a perspective on the intricacies and complexities of those occurrences, and on the elements of continuity and gradualism in even the most radical changes; and for our general understanding of historical process in the history of the sciences, it shows the importance of the broader scientific research community for even the most individual accomplishments.

Effect of feeding graded doses of Citrinin on clinical and teratology in female Wistar rats.

PubMed

Singh, N D; Sharma, A K; Patil, R D; Rahman, S; Leishangthem, G D; Kumar, M

2014-02-01

Citrinin is the one of the well-known mycotoxins, which is possibly spread all over the world. The graded doses of citrinin (1, 3 and 5 ppm CIT in feed) in female Wistar rats 10 weeks prior to mating, during mating and during organogenesis resulted in resorptions and post implantation losses, decreased fetal body weights and crown-rump lengths in fetuses of all groups. Various developmental anomalies recorded in fetuses of treated rats included gross (wrist drop, curled tail, stretched forelimb, subcutaneous haematoma), skeletal (incomplete ossification of skull bones, incomplete fusion of vertebral bodies, complete and partial agenesis of sternaebrae, metacarpals, metatarsals and phalanges, fused ribs and swing out ribs) and visceral (internal and external hydrocephalus, cerebellar hypoplasia, microphthalmia, roundening of heart, contracted kidneys, dilated renal pelvis and cryptorchid testes). The results suggest that CIT has adverse effects on fetal development which may be due to the longer bioavailability of citrinin in the animals.

30 CFR 1206.102 - How do I calculate royalty value for oil that I or my affiliate sell(s) under an arm's-length...

Code of Federal Regulations, 2012 CFR

2012-07-01

... or my affiliate sell(s) under an arm's-length contract? 1206.102 Section 1206.102 Mineral Resources...) under an arm's-length contract? (a) The value of oil under this section is the gross proceeds accruing to the seller under the arm's-length contract, less applicable allowances determined under § 1206.110...

30 CFR 1206.102 - How do I calculate royalty value for oil that I or my affiliate sell(s) under an arm's-length...

Code of Federal Regulations, 2013 CFR

2013-07-01

... or my affiliate sell(s) under an arm's-length contract? 1206.102 Section 1206.102 Mineral Resources...) under an arm's-length contract? (a) The value of oil under this section is the gross proceeds accruing to the seller under the arm's-length contract, less applicable allowances determined under § 1206.110...

30 CFR 1206.102 - How do I calculate royalty value for oil that I or my affiliate sell(s) under an arm's-length...

Code of Federal Regulations, 2014 CFR

2014-07-01

... or my affiliate sell(s) under an arm's-length contract? 1206.102 Section 1206.102 Mineral Resources...) under an arm's-length contract? (a) The value of oil under this section is the gross proceeds accruing to the seller under the arm's-length contract, less applicable allowances determined under § 1206.110...

30 CFR 1206.102 - How do I calculate royalty value for oil that I or my affiliate sell(s) under an arm's-length...

Code of Federal Regulations, 2011 CFR

2011-07-01

... or my affiliate sell(s) under an arm's-length contract? 1206.102 Section 1206.102 Mineral Resources... affiliate sell(s) under an arm's-length contract? (a) The value of oil under this section is the gross proceeds accruing to the seller under the arm's-length contract, less applicable allowances determined...

Quantifying wall turbulence via a symmetry approach: A Lie group theory

NASA Astrophysics Data System (ADS)

She, Zhen-Su; Chen, Xi; Hussain, Fazle

2017-11-01

We present a symmetry-based approach which yields analytic expressions for the mean velocity and kinetic energy profiles from a Lie-group analysis. After verifying the dilation-group invariance of the Reynolds averaged Navier-Stokes equation in the presence of a wall, we select a stress and energy length function as similarity variables which are assumed to have a simple dilation-invariant form. Three kinds of (local) invariant forms of the length functions are postulated, a combination of which yields a multi-layer formula giving its distribution in the entire flow region normal to the wall. The mean velocity profile is then predicted using the mean momentum equation, which yields, in particular, analytic expressions for the (universal) wall function and separate wake functions for pipe and channel - which are validated by data from direct numerical simulations (DNS). Future applications to a variety of wall flows such as flows around flat plate or airfoil, in a Rayleigh-Benard cell or Taylor-Couette system, etc., are discussed, for which the dilation group invariance is valid in the wall-normal direction.

Complex myograph allows the examination of complex muscle contractions for the assessment of muscle force, shortening, velocity, and work in vivo

PubMed Central

Rahe-Meyer, Niels; Pawlak, Matthias; Weilbach, Christian; Osthaus, Wilhelm Alexander; Ruhschulte, Hainer; Solomon, Cristina; Piepenbrock, Siegfried; Winterhalter, Michael

2008-01-01

Background The devices used for in vivo examination of muscle contractions assess only pure force contractions and the so-called isokinetic contractions. In isokinetic experiments, the extremity and its muscle are artificially moved with constant velocity by the measuring device, while a tetanic contraction is induced in the muscle, either by electrical stimulation or by maximal voluntary activation. With these systems, experiments cannot be performed at pre-defined, constant muscle length, single contractions cannot be evaluated individually and the separate examination of the isometric and the isotonic components of single contractions is not possible. Methods The myograph presented in our study has two newly developed technical units, i.e. a). a counterforce unit which can load the muscle with an adjustable, but constant force and b). a length-adjusting unit which allows for both the stretching and the contraction length to be infinitely adjustable independently of one another. The two units support the examination of complex types of contraction and store the counterforce and length-adjusting settings, so that these conditions may be accurately reapplied in later sessions. Results The measurement examples presented show that the muscle can be brought to every possible pre-stretching length and that single isotonic or complex isometric-isotonic contractions may be performed at every length. The applied forces act during different phases of contraction, resulting into different pre- and after-loads that can be kept constant – uninfluenced by the contraction. Maximal values for force, shortening, velocity and work may be obtained for individual muscles. This offers the possibility to obtain information on the muscle status and to monitor its changes under non-invasive measurement conditions. Conclusion With the Complex Myograph, the whole spectrum of a muscle's mechanical characteristics may be assessed. PMID:18616815

New and emerging biomarkers in left ventricular systolic dysfunction--insight into dilated cardiomyopathy.

PubMed

Gopal, Deepa M; Sam, Flora

2013-08-01

Dilated cardiomyopathy (DCM) is characterized by deteriorating cardiac performance, impaired contraction and dilation of the left ventricle (or both ventricles). Blood markers--known as "biomarkers"--allow insight into underlying pathophysiologic mechanisms and biologic pathways while predicting outcomes and guiding heart failure management and/or therapies. In this review, we provide an alternative approach to conceptualize heart failure biomarkers: the cardiomyocyte, its surrounding microenvironment, and the macroenvironment, integrating these entities which may impact cellular processes involved in the pathogenesis and/or propagation of DCM. Newer biomarkers of left ventricular systolic dysfunction can be categorized under: (a) myocyte stress and stretch, (b) myocyte apoptosis, (c) cardiac interstitium, (d) inflammation, (e) oxidative stress, (f) cardiac energetics, (g) neurohormones, and (h) renal biomarkers. Biomarkers provide insight into the pathogenesis of DCM while predicting and potentially providing prognostic information in these patients with heart failure.

New and Emerging Biomarkers in Left Ventricular Systolic Dysfunction - Insight into Dilated Cardiomyopathy

PubMed Central

Gopal, Deepa M.; Sam, Flora

2013-01-01

Background Dilated cardiomyopathy (DCM) is characterized by deteriorating cardiac performance and impaired contraction and dilation of the left (or both) ventricles. Blood markers – known as “biomarkers” allow insight into underlying pathophysiologic mechanisms and biologic pathways, while predicting outcomes and guiding heart failure management and/or therapies. Content In this review, we provide an alternative approach to conceptualize heart failure biomarkers: the cardiomyocyte, its surrounding microenvironment, and the macroenvironment with clear interaction between these entities which may impact cellular processes involved in the pathogenesis and/or propagation of DCM. Newer biomarkers of left ventricular systolic dysfunction can be categorized under: (a) myocyte stress and stretch, (b) myocyte apoptosis, (c) cardiac interstitium, (d) inflammation, (e) oxidative stress, (f) cardiac energetics, (g) neurohormones and (h) renal biomarkers. Summary Biomarkers provide insight into the pathogenesis of DCM while predicting and potentially providing prognostic information in these patients with heart failure. PMID:23609585

Ultrasonography and renography to visualize upper urinary tract in children with meningomyelocele - a prospective study.

PubMed

Abrahamsson, Kate; Stokland, Eira; Sixt, Rune; Jodal, Ulf

2012-04-01

Ultrasonography (US) is commonly used to visualize the upper urinary tract in children and adolescents with meningomyelocele (MMC). The aim of this investigation was to prospectively evaluate US in those with spinal angulation or obesity and compare it to the corresponding results obtained by mercaptoacetyltriglycine renography. Twenty-five children and adolescents with MMC and pronounced angulation of the spine or obesity, were prospectively investigated with both US and renography during the period 2006 to 2008. In 13 (52%) patients the kidneys could not be fully evaluated; in 4 (16%) neither renal size nor pelvic dilation, in 12 (48%) renal length and in 5 (20%) dilation was not accessible. In 23 individuals where dilatation could be evaluated uni- or bilaterally, US was compared to OEE% (%outflow excretion efficiency) at renography. In 1 of these individuals there was normal OEE% while slight dilatation on US was noticed. In 2/15 individuals, split function at renography did not correlate with renal length on US. Severe spinal angulation and obesity in individuals with MMC reduced the possibility to evaluate the urinary tract by US. However, it seems that renography could be a reliable alternative to evaluate renal condition in those patients where US is insufficient. Copyright © 2011 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.

High prevalence of myocardial monoclonal antimyosin antibody uptake in patients with chronic idiopathic dilated cardiomyopathy

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

Obrador, D.; Ballester, M.; Carrio, I.

1989-05-01

Monoclonal antimyosin antibody studies were undertaken to assess the presence of myocardial uptake in patients with chronic idiopathic dilated cardiomyopathy. Three groups were studied: 17 patients with chronic (greater than 12 months) idiopathic dilated cardiomyopathy, 12 patients with a large, poorly contracting left ventricle not due to dilated cardiomyopathy (control patients) and 8 normal individuals. The patients in the cardiomyopathy and control groups showed a similar degree of clinical and functional impairment. Imaging was undertaken 48 h after antimyosin injection. The heart/lung ratio of antimyosin uptake was used to assess the results. The mean ratio in the cardiomyopathy group wasmore » 1.83 +/- 0.36 (range 1.40 to 2.80), a value significantly higher than that obtained in the control patients without cardiomyopathy (mean 1.46 +/- 0.04, range 1.38 to 1.50) or normal subjects (mean 1.46 +/- 0.13, range 1.31 to 1.6) (p less than 0.01). No difference in the ratio was noted between the normal subjects and control patients. Abnormal antimyosin uptake was seen in 12 (70%) of the 17 patients with cardiomyopathy and in only 1 (8%) of the 12 control patients. Positive monoclonal antimyosin antibody studies are highly prevalent in chronic idiopathic dilated cardiomyopathy.« less

The effect of pulmonary hypertension on ovine tricuspid annular dynamics.

PubMed

Malinowski, Marcin; Wilton, Penny; Khaghani, Asghar; Langholz, David; Hooker, Victoria; Eberhart, Lenora; Hooker, Robert L; Timek, Tomasz A

2016-01-01

Pulmonary hypertension (PHT) is associated with tricuspid annular dilatation, but the effect of acute increase of pulmonary pressure on three-dimensional (3D) tricuspid annular dynamics and shape is unknown. Better understanding of tricuspid annular dynamics may lead to improved and more durable surgical reparative techniques. In nine open-chest anaesthetized sheep nine sonomicrometry crystals were implanted on the right ventricle while on cardiopulmonary bypass. Additional nine crystals were implanted around the tricuspid annulus (TA) with one crystal at each commissure defining three separate annular regions: anterior, posterior and septal. Two additional equidistant crystals were implanted between each commissure, creating three segments for every region. Pressure transducers were placed in the left ventricular (LV), right ventricular (RV) and right atrium. PHT was induced by acute pulmonary artery constriction with a pneumatic occluder. Sonomicrometry and echocardiographic data were collected before and after induction of PHT. TA area, regional and total perimeter, and 3D annular geometry were calculated from 3D crystal coordinates. Regional annular contraction was defined as the percentage difference between maximal and minimal region length during the cardiac cycle. PHT increased RV pressure from 31 ± 9 mmHg to 46 ± 13 mmHg (P = 0.001) and decreased left ventricular (LV) pressure from 111 ± 24 mmHg to 78 ± 36 mmHg (P = 0.018). There was no significant tricuspid regurgitation observed with PHT. During PHT, the TA area increased by 12 ± 13% from 641 ± 139 mm(2) to 721 ± 177 mm(2) (P = 0.037). The total perimeter increased from 103 ± 11 mm to 109 ± 13 mm (P = 0.02). All annular regions dilated significantly with PHT with 8 ± 10, 5 ± 5 and 5 ± 5% increase in anterior, posterior and septal annular length, respectively (P < 0.05). PHT reduced regional annular contraction in the anterior region only (17 ± 7 vs 14 ± 8%; P = 0.02). The TA had a complex 3D saddle geometry and the shape of the annulus was altered during PHT only in the antero-posterior region. The changes in tricuspid annular conformation, contractility and its 3D geometry observed during acute ovine PHT may help in the design of new pathology-specific tricuspid annular rings. © The Author 2015. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Two-Phase Solid/Fluid Simulation of Dense Granular Flows With Dilatancy Effects

NASA Astrophysics Data System (ADS)

Mangeney, Anne; Bouchut, Francois; Fernandez-Nieto, Enrique; Narbona-Reina, Gladys; Kone, El Hadj

2017-04-01

Describing grain/fluid interaction in debris flows models is still an open and challenging issue with key impact on hazard assessment [1]. We present here a two-phase two-thin-layer model for fluidized debris flows that takes into account dilatancy effects. It describes the velocity of both the solid and the fluid phases, the compression/ dilatation of the granular media and its interaction with the pore fluid pressure [2]. The model is derived from a 3D two-phase model proposed by Jackson [3] and the mixture equations are closed by a weak compressibility relation. This relation implies that the occurrence of dilation or contraction of the granular material in the model depends on whether the solid volume fraction is respectively higher or lower than a critical value. When dilation occurs, the fluid is sucked into the granular material, the pore pressure decreases and the friction force on the granular phase increases. On the contrary, in the case of contraction, the fluid is expelled from the mixture, the pore pressure increases and the friction force diminishes. To account for this transfer of fluid into and out of the mixture, a two-layer model is proposed with a fluid or a solid layer on top of the two-phase mixture layer. Mass and momentum conservation are satisfied for the two phases, and mass and momentum are transferred between the two layers. A thin-layer approximation is used to derive average equations. Special attention is paid to the drag friction terms that are responsible for the transfer of momentum between the two phases and for the appearance of an excess pore pressure with respect to the hydrostatic pressure. Interestingly, when removing the role of water, our model reduces to a dry granular flow model including dilatancy. We first compare experimental and numerical results of dilatant dry granular flows. Then, by quantitatively comparing the results of simulation and laboratory experiments on submerged granular flows, we show that our model contains the basic ingredients making it possible to reproduce the interaction between the granular and fluid phases through the change in pore fluid pressure. In particular, we analyse the different time scales in the model and their role in granular/fluid flow dynamics. References [1] R. Delannay, A. Valance, A. Mangeney, O. Roche, P. Richard, J. Phys. D: Appl. Phys., in press (2016). [2] F. Bouchut, E. D. Fernández-Nieto, A. Mangeney, G. Narbona-Reina, J. Fluid Mech., 801, 166-221 (2016). [3] R. Jackson, Cambridges Monographs on Mechanics (2000).

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

Connecting macroscopic dynamics with microscopic properties in active microtubule network contraction

NASA Astrophysics Data System (ADS)

Foster, Peter J.; Yan, Wen; Fürthauer, Sebastian; Shelley, Michael J.; Needleman, Daniel J.

2017-12-01

The cellular cytoskeleton is an active material, driven out of equilibrium by molecular motor proteins. It is not understood how the collective behaviors of cytoskeletal networks emerge from the properties of the network’s constituent motor proteins and filaments. Here we present experimental results on networks of stabilized microtubules in Xenopus oocyte extracts, which undergo spontaneous bulk contraction driven by the motor protein dynein, and investigate the effects of varying the initial microtubule density and length distribution. We find that networks contract to a similar final density, irrespective of the length of microtubules or their initial density, but that the contraction timescale varies with the average microtubule length. To gain insight into why this microscopic property influences the macroscopic network contraction time, we developed simulations where microtubules and motors are explicitly represented. The simulations qualitatively recapitulate the variation of contraction timescale with microtubule length, and allowed stress contributions from different sources to be estimated and decoupled.

Comparison of the efficiency of rat papillary muscles during afterloaded isotonic contractions and contractions with sinusoidal length changes.

PubMed

Mellors, L J; Gibbs, C L; Barclay, C J

2001-05-01

The results of previous studies suggest that the maximum mechanical efficiency of rat papillary muscles is lower during a contraction protocol involving sinusoidal length changes than during one involving afterloaded isotonic contractions. The aim of this study was to compare directly the efficiency of isolated rat papillary muscle preparations in isotonic and sinusoidal contraction protocols. Experiments were performed in vitro (27 degrees C) using left ventricular papillary muscles from adult rats. Each preparation performed three contraction protocols: (i) low-frequency afterloaded isotonic contractions (10 twitches at 0.2 Hz), (ii) sinusoidal length change contractions with phasic stimulation (40 twitches at 2 Hz) and (iii) high-frequency afterloaded isotonic contractions (40 twitches at 2 Hz). The first two protocols resembled those used in previous studies and the third combined the characteristics of the first two. The parameters for each protocol were adjusted to those that gave maximum efficiency. For the afterloaded isotonic protocols, the afterload was set to 0.3 of the maximum developed force. The sinusoidal length change protocol incorporated a cycle amplitude of +/-5% resting length and a stimulus phase of -10 degrees. Measurements of force output, muscle length change and muscle temperature change were used to calculate the work and heat produced during and after each protocol. Net mechanical efficiency was defined as the proportion of the energy (enthalpy) liberated by the muscle that appeared as work. The efficiency in the low-frequency, isotonic contraction protocol was 21.1+/-1.4% (mean +/- s.e.m., N=6) and that in the sinusoidal protocol was 13.2+/-0.7%, consistent with previous results. This difference was not due to the higher frequency or greater number of twitches because efficiency in the high-frequency, isotonic protocol was 21.5+/-1.0%. Although these results apparently confirm that efficiency is protocol-dependent, additional experiments designed to measure work output unambiguously indicated that the method used to calculate work output in isotonic contractions overestimated actual work output. When net work output, which excludes work done by parallel elastic elements, rather than total work output was used to determine efficiency in afterloaded isotonic contractions, efficiency was similar to that for sinusoidal contractions. The maximum net mechanical efficiency of rat papillary muscles performing afterloaded isotonic or sinusoidal length change contractions was between 10 and 15%.

Vasoactivity of rucaparib, a PARP-1 inhibitor, is a complex process that involves myosin light chain kinase, P2 receptors, and PARP itself.

PubMed

McCrudden, Cian M; O'Rourke, Martin G; Cherry, Kim E; Yuen, Hiu-Fung; O'Rourke, Declan; Babur, Muhammad; Telfer, Brian A; Thomas, Huw D; Keane, Patrick; Nambirajan, Thiagarajan; Hagan, Chris; O'Sullivan, Joe M; Shaw, Chris; Williams, Kaye J; Curtin, Nicola J; Hirst, David G; Robson, Tracy

2015-01-01

Therapeutic inhibition of poly(ADP-ribose) polymerase (PARP), as monotherapy or to supplement the potencies of other agents, is a promising strategy in cancer treatment. We previously reported that the first PARP inhibitor to enter clinical trial, rucaparib (AG014699), induced vasodilation in vivo in xenografts, potentiating response to temozolomide. We now report that rucaparib inhibits the activity of the muscle contraction mediator myosin light chain kinase (MLCK) 10-fold more potently than its commercially available inhibitor ML-9. Moreover, rucaparib produces additive relaxation above the maximal degree achievable with ML-9, suggesting that MLCK inhibition is not solely responsible for dilation. Inhibition of nitric oxide synthesis using L-NMMA also failed to impact rucaparib's activity. Rucaparib contains the nicotinamide pharmacophore, suggesting it may inhibit other NAD+-dependent processes. NAD+ exerts P2 purinergic receptor-dependent inhibition of smooth muscle contraction. Indiscriminate blockade of the P2 purinergic receptors with suramin abrogated rucaparib-induced vasodilation in rat arterial tissue without affecting ML-9-evoked dilation, although the specific receptor subtypes responsible have not been unequivocally identified. Furthermore, dorsal window chamber and real time tumor vessel perfusion analyses in PARP-1-/- mice indicate a potential role for PARP in dilation of tumor-recruited vessels. Finally, rucaparib provoked relaxation in 70% of patient-derived tumor-associated vessels. These data provide tantalising evidence of the complexity of the mechanism underlying rucaparib-mediated vasodilation.

Treatment of severe peptic esophageal stricture with Roux-en-Y partial gastrectomy, vagotomy, and endoscopic dilation. A follow-up study.

PubMed

Salo, J A; Ala-Kulju, K V; Heikkinen, L O; Kivilaakso, E O

1991-04-01

Eleven patients with dysphagia caused by severe esophageal stricture (length 2 to 10 cm) resulting from reflux esophagitis were treated with fibroendoscopic dilation (Eder-Puestow) and Roux-en-Y partial gastrectomy with vagotomy during 10 years (1979 to 1988). There was no operative mortality, but complications developed in three patients: One patient had a mediastinal abscess demanding thoracotomy as a result of esophageal perforation after dilatation; one had postoperative pneumonia; and one patient had ileus. After a mean follow-up of 4 years (range 1 to 10 years) esophagitis healed in all cases, as judged by endoscopy. Eight patients were asymptomatic, but three had slight transient dysphagia. Postoperatively one to eight dilations (average three to four) were needed to relieve dysphagia in the first postoperative year, but later the stricture healed in every case. Postoperative pH measurement was performed in six latest patients and showed complete absence of reflux in all cases. It is concluded that Roux-en-Y partial gastrectomy with vagotomy and endoscopic dilation is an effective, simple, and safe procedure in the management of severe peptic esophageal (acid or alkaline esophagitis) stricture. However, occasional postoperative dilations at the outpatient clinic are often needed in severe cases in the first postoperative year.

Role of cooperative structural distortions in the metal--insulator transitions of perovskite ferrates

NASA Astrophysics Data System (ADS)

Cammarata, Antonio; Rondinelli, James

2012-02-01

Transition-metal oxides within the perovskite crystal family exhibit strong electron--electron correlation effects that coexist with complex structural distortions, leading to metal-insulator (MI) transitions. Using first-principles density functional calculations, we investigate the effects of cooperative octahedral rotations and dilations/contractions on the charge-ordering MI-transition in CaFeO3. By calculating the evolution in the lattice phonons, which describe the different octahedral distortions present in the low-symmetry monoclinic phase of CaFeO3 with increasing electron correlation, we show that the MI-transition results from a complex interplay between these modes and correlation effects. We combine this study with group theoretical tools to disentangle the electron--lattice interactions by computing the evolution in the low-energy electronic band structure with the lattice phonons, demonstrating the MI-transition in CaFeO3 proceeds through a symmetry-lowering transition driven by a cooperative three-dimensional octahedral dilation/contraction pattern. Finally, we suggest a possible route by which to control the charge ordering by fine-tuning the electron--lattice coupling.

Bond length variation in Zn substituted NiO studied from extended X-ray absorption fine structure

NASA Astrophysics Data System (ADS)

Singh, S. D.; Poswal, A. K.; Kamal, C.; Rajput, Parasmani; Chakrabarti, Aparna; Jha, S. N.; Ganguli, Tapas

2017-06-01

Bond length behavior for Zn substituted NiO is determined through extended x-ray absorption fine structure (EXAFS) measurements performed at ambient conditions. We report bond length value of 2.11±0.01 Å for Zn-O of rock salt (RS) symmetry, when Zn is doped in RS NiO. Bond length for Zn substituted NiO RS ternary solid solutions shows relaxed behavior for Zn-O bond, while it shows un-relaxed behavior for Ni-O bond. These observations are further supported by first-principles calculations. It is also inferred that Zn sublattice remains nearly unchanged with increase in lattice parameter. On the other hand, Ni sublattice dilates for Zn compositions up to 20% to accommodate increase in the lattice parameter. However, for Zn compositions more than 20%, it does not further dilate. It has been attributed to the large disorder that is incorporated in the system at and beyond 20% of Zn incorporation in the cubic RS lattice of ternary solid solutions. For these large percentages of Zn incorporation, the Ni and the Zn atoms re-arrange themselves microscopically about the same nominal bond length rather than systematically increase in magnitude to minimize the energy of the system. This results in an increase in the Debye-Waller factor with increase in the Zn concentration rather than a systematic increase in the bond lengths.

A review of techniques of induced abortion.

PubMed

Hepburn, S

1981-04-01

Various techniques are available for inducing abortion. Evacuation of the uterus through the vagina is generally the preferred method in first trimester pregnancies. Dilation of the cervical canal by inserting rod dilators or laminaria tents allows the withdrawal of the fetus. Suction procedures (vacuum aspiration, uterine aspiration, or suction curettage) are possible since the decidua are separable from the basal layer of endometrium. This removal by force does not damage other maternal tissue. A cannula is introduced into the uterine cavity through the dilated cervix and its operator is then connected to a pump by way of a flexible tube which delivers negative pressure of about 600 mm of mercury. When the fetus is withdrawn, the uterus is felt to contract onto the cannula. The average time for this procedure is 5 minutes. Surgical curettage or dilatation and evacuation first dilates the cervical canal and then removes fetal parts and tissue from ovum forceps; a sharp curette does the rest. Anesthesia for these procedures may be general, local, or spinal. The techniques of menstrual regulation is used before pregnancy can be confirmed. However with the advent of the RIA test for the beta subunit of HCG this procedure is rarely indicated. Induction of premature labor is used in the later 1/2 of the second trimester and utilizes prostaglandins. Intraamniobor usually begins within 24 hours. Hysterotomy and hysterectomy are surgical procedures used in abortions.

Urinary Retention

MedlinePlus

... urinary retention with • bladder drainage • urethral dilation • urethral stents • prostate medications • surgery The type and length of ... patient will receive sedation and regional anesthesia. Urethral Stents Another treatment for urethral stricture involves inserting an ...

30 CFR 1206.52 - How do I calculate royalty value for oil that I or my affiliate sell(s) or exchange(s) under an...

Code of Federal Regulations, 2011 CFR

2011-07-01

... or my affiliate sell(s) or exchange(s) under an arm's-length contract? 1206.52 Section 1206.52... my affiliate sell(s) or exchange(s) under an arm's-length contract? (a) The value of oil under this section is the gross proceeds accruing to the seller under the arm's-length contract, less applicable...

30 CFR 1206.52 - How do I calculate royalty value for oil that I or my affiliate sell(s) or exchange(s) under an...

Code of Federal Regulations, 2014 CFR

2014-07-01

... or my affiliate sell(s) or exchange(s) under an arm's-length contract? 1206.52 Section 1206.52... affiliate sell(s) or exchange(s) under an arm's-length contract? (a) The value of oil under this section is the gross proceeds accruing to the seller under the arm's-length contract, less applicable allowances...

30 CFR 1206.52 - How do I calculate royalty value for oil that I or my affiliate sell(s) or exchange(s) under an...

Code of Federal Regulations, 2013 CFR

2013-07-01

... or my affiliate sell(s) or exchange(s) under an arm's-length contract? 1206.52 Section 1206.52... affiliate sell(s) or exchange(s) under an arm's-length contract? (a) The value of oil under this section is the gross proceeds accruing to the seller under the arm's-length contract, less applicable allowances...

30 CFR 1206.52 - How do I calculate royalty value for oil that I or my affiliate sell(s) or exchange(s) under an...

Code of Federal Regulations, 2012 CFR

2012-07-01

... or my affiliate sell(s) or exchange(s) under an arm's-length contract? 1206.52 Section 1206.52... affiliate sell(s) or exchange(s) under an arm's-length contract? (a) The value of oil under this section is the gross proceeds accruing to the seller under the arm's-length contract, less applicable allowances...

Serelaxin Elicits Bronchodilation and Enhances β-Adrenoceptor-Mediated Airway Relaxation

PubMed Central

Lam, Maggie; Royce, Simon G.; Donovan, Chantal; Jelinic, Maria; Parry, Laura J.; Samuel, Chrishan S.; Bourke, Jane E.

2016-01-01

Treatment with β-adrenoceptor agonists does not fully overcome the symptoms associated with severe asthma. Serelaxin elicits potent uterine and vascular relaxation via its cognate receptor, RXFP1, and nitric oxide (NO) signaling, and is being clinically evaluated for the treatment of acute heart failure. However, its direct bronchodilator efficacy has yet to be explored. Tracheal rings were prepared from male Sprague-Dawley rats (250–350 g) and tricolor guinea pigs, and precision cut lung slices (PCLSs) containing intrapulmonary airways were prepared from rats only. Recombinant human serelaxin (rhRLX) alone and in combination with rosiglitazone (PPARγ agonist; recently described as a novel dilator) or β-adrenoceptor agonists (isoprenaline, salbutamol) were added either to pre-contracted airways, or before contraction with methacholine or endothelin-1. Regulation of rhRLX responses by epithelial removal, indomethacin (cyclooxygenase inhibitor), L-NAME (nitric oxide synthase inhibitor), SQ22536 (adenylate cyclase inhibitor) and ODQ (guanylate cyclase inhibitor) were also evaluated. Immunohistochemistry was used to localize RXFP1 to airway epithelium and smooth muscle. rhRLX elicited relaxation in rat trachea and PCLS, more slowly than rosiglitazone or isoprenaline, but potentiated relaxation to both these dilators. It markedly increased β-adrenoceptor agonist potency in guinea pig trachea. rhRLX, rosiglitazone, and isoprenaline pretreatment also inhibited the development of rat tracheal contraction. Bronchoprotection by rhRLX increased with longer pre-incubation time, and was partially reduced by epithelial removal, indomethacin and/or L-NAME. SQ22536 and ODQ also partially inhibited rhRLX-mediated relaxation in both intact and epithelial-denuded trachea. RXFP1 expression in the airways was at higher levels in epithelium than smooth muscle. In summary, rhRLX elicits large and small airway relaxation via epithelial-dependent and -independent mechanisms, likely via RXFP1 activation and generation of NO, prostaglandins and cAMP/cGMP. rhRLX also enhanced responsiveness to other dilators, suggesting its potential as an alternative or add-on therapy for severe asthma. PMID:27833558

Importance of early diagnosis of pancreaticobiliary maljunction without biliary dilatation

PubMed Central

Takuma, Kensuke; Kamisawa, Terumi; Tabata, Taku; Hara, Seiichi; Kuruma, Sawako; Inaba, Yoshihiko; Kurata, Masanao; Honda, Goro; Tsuruta, Koji; Horiguchi, Shin-ichiro; Igarashi, Yoshinori

2012-01-01

AIM: To clarify the strategy for early diagnosis of pancreaticobiliary maljunction (PBM) without biliary dilatation and to pathologically examine gallbladder before cancer develops. METHODS: The anatomy of the union of the pancreatic and bile ducts was assessed by using endoscopic retrograde cholangiopancreatography (ERCP). Patients with a long common channel in which communication between the pancreatic and bile ducts was maintained even during sphincter contraction were diagnosed as having PBM. Of these, patients in which the maximal diameter of the bile duct was less than 10 mm were diagnosed with PBM without biliary dilatation. The process of diagnosing 54 patients with PBM without biliary dilatation was retrospectively investigated. Histopathological analysis of resected gallbladder specimens from 8 patients with PBM without biliary dilatation or cancer was conducted. RESULTS: Thirty-six PBM patients without biliary dilatation were diagnosed with gallbladder cancer after showing clinical symptoms such as abdominal or back pain (n = 16) or jaundice (n = 12). Radical surgery for gallbladder cancer was only possible in 11 patients (31%) and only 4 patients (11%) survived for 5 years. Eight patients were suspected as having PBM without biliary dilatation from the finding of gallbladder wall thickening on ultrasound and the diagnosis was confirmed by ERCP and/or magnetic resonance cholangiopancreatography (MRCP). The median age of these 8 patients was younger by a decade than PBM patients with gallbladder cancer. All 8 patients underwent prophylactic cholecystectomy and bile duct cancer has not occurred. Wall thickness and mucosal height of the 8 resected gallbladders were significantly greater than controls, and hyperplastic changes, hypertrophic muscular layer, subserosal fibrosis, and adenomyomatosis were detected in 7 (88%), 5 (63%), 7 (88%) and 5 (63%) patients, respectively. Ki-67 labeling index was high and K-ras mutation was detected in 3 of 6 patients. CONCLUSION: To detect PBM without biliary dilatation before onset of gallbladder cancer, we should perform MRCP for individuals showing increased gallbladder wall thickness on ultrasound. PMID:22807610

Measurement of the Surface Dilatational Viscosity of an Insoluble Surfactant Monolayer at the Air/Water Interface Using a Pendant Drop Apparatus

NASA Technical Reports Server (NTRS)

Lorenzo, Jose; Couzis, Alex; Maldarelli, Charles; Singh, Bhim S. (Technical Monitor)

2000-01-01

When a fluid interface with surfactants is at rest, the interfacial stress is isotropic (as given by the equilibrium interfacial tension), and is described by the equation of state which relates the surface tension to the surfactant surface concentration. When surfactants are subjected to shear and dilatational flows, flow induced interaction of the surfactants; can create interfacial stresses apart from the equilibrium surface tension. The simplest relationship between surface strain rate and surface stress is the Boussinesq-Scriven constitutive equation completely characterized by three coefficients: equilibrium interfacial tension, surface shear viscosity, and surface dilatational viscosity Equilibrium interfacial tension and surface shear viscosity measurements are very well established. On the other hand, surface dilatational viscosity measurements are difficult because a flow which change the surface area also changes the surfactant surface concentration creating changes in the equilibrium interfacial tension that must be also taken into account. Surface dilatational viscosity measurements of existing techniques differ by five orders of magnitude and use spatially damped surface waves and rapidly expanding bubbles. In this presentation we introduce a new technique for measuring the surface dilatational viscosity by contracting an aqueous pendant drop attached to a needle tip and having and insoluble surfactant monolayer at the air-water interface. The isotropic total tension on the surface consists of the equilibrium surface tension and the tension due to the dilation. Compression rates are undertaken slow enough so that bulk hydrodynamic stresses are small compared to the surface tension force. Under these conditions we show that the total tension is uniform along the surface and that the Young-Laplace equation governs the drop shape with the equilibrium surface tension replaced by the constant surface isotropic stress. We illustrate this technique using DPPC as the insoluble surfacant monolayer and measured for it a surface dilatational viscosity in the LE phase that is 20 surface poise.

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.

Exploring full cervical dilatation caesarean sections-A retrospective cohort study.

PubMed

Corry, Edward M A; Ramphul, Meenakshi; Rowan, Ann M; Segurado, Ricardo; Mahony, Rhona M; Keane, Declan P

2018-05-01

The rate of caesarean sections at full cervical dilatation with their high risk of morbidity continues to rise mirroring the overall increase in caesarean section rates internationally. The objectives of this study were to determine the rate of full dilatation caesarean section in a tertiary referral unit and evaluate key labour, maternal and fetal factors potentially linked to those deliveries. We also assessed maternal and fetal morbidity at full dilatation sections. Where possible, these were compared with successful operative vaginal deliveries carried out in theatre to determine key differences. Retrospective cohort study. We reviewed the rate of full dilatation caesarean section over a 10-year period. We analysed deliveries (caesarean sections or operative vaginal deliveries) in single cephalic pregnancies ≥34 weeks with contemporaneously collected data from our unit's electronic database for 2015. The rate of full dilatation caesarean section increased by over a third in the ten-year period (56/6947 (0.80%) vs 92/7378 (1.24%), p = 0.01). Of 84 full dilatation caesarean sections who met the inclusion criteria, 63 (75%) were nulliparous and the mean maternal age was 33 (±5) years. Oxytocin was used in the second stage in less than half of second stage caesarean sections (22 out of a recorded 57, 38.6%). There were more fetal head malposition (occipito-posterior, or occipito-transverse) at full dilatation caesarean section compared to successful operative vaginal deliveries (41/46 (89.1%) vs 2/21 (9.5), p < 0.001). The rate of significant postpartum haemorrhage (defined as estimated blood loss ≥1000 ml) was similar in both full dilatation caesarean section and operative vaginal deliveries. There was no difference in the mean birthweight at full dilatation caesarean sections compared to operative vaginal delivery (3.88 kg (2.80-5.33 kg) vs 3.48 kg (1.53-4.40 kg)). There was no difference in neonatal morbidity. Fetal head malposition is associated with a higher risk of full dilatation caesarean section. Interestingly, maternal and fetal morbidity were similar between full dilatation caesarean sections and anticipated difficult operative vaginal deliveries carried out in theatre. The management of labour in terms of the decision to use oxytocin judiciously in hope of correcting inefficient uterine contractions and continuous labour ward training, particularly the diagnosis of malposition and its correction may be beneficial in reducing the rate of full dilation caesarean sections. Copyright © 2018 Elsevier B.V. All rights reserved.

Evolving understanding and treatment of labour dystocia.

PubMed

Karaçam, Zekiye; Walsh, Denis; Bugg, George John

2014-11-01

The objective of the review is to critically review the diagnosis and management of dystocia in the first stage of labour. We conducted a narrative review of research since 1998. Eight studies were identified, four about the onset and duration of active phase of the first stage of labour, one on the diagnosis of dystocia, and three focused on the treatment of dystocia. The review demonstrates that current understandings of dystocia rest on outdated definitions of active first stage of labour, its progress and on treatments with an equivocal evidence base. These include the cervical dilatation threshold for active first stage, uncertainty over whether a reduced rate of dilatation and reduced strength of uterine contractions always represent pathology and the effectiveness of amniotomy/oxytocin for treating dystocia. Prospective studies should evaluate the impact of defining the active phase of the first stage of labour as commencing at 6 cm dilated and should test this definition in combination with Zhang's revised partogram. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Shallow fluid pressure transients caused by seismogenic normal faults

NASA Astrophysics Data System (ADS)

Fleischmann, Karl Henry

1993-10-01

Clastic dikes, induced by paleo-seismic slip along the Jonesboro Fault, can be used to estimate the magnitude of shallow fluid pressure transients. Fractures show evidence of two phases of seismically induced dilation by escaping fluids. Initial dilation and propagation through brittle rocks was caused by expulsion of trapped reducing fluids from beneath a clay cap. Second phase fluids were thixotropic clays which flowed vertically from clay beds upwards into the main fracture. Using the differential dilation and fracture trace lengths, the fluid pressure pulse is estimated to have ranged from 0.312-0.49 MPa, which is approximately equal to the vertical load during deformation. Field observations in adjacent rocks record evidence of large-magnitude seismic events, which are consistent with the large nature of the fluid pressure fluctuation.

Teaching Special Relativity Without Calculus

NASA Astrophysics Data System (ADS)

Ruby, Lawrence

2009-04-01

I 2007 many AAPT members received a booklet that is the first chapter of a physics textbook available on a CD. This book espouses the new educational philosophy of teaching special relativity as the first item in the topic of mechanics. Traditionally, special relativity is part of one or more modern physics chapters at the end of the text,2 and very often this material is never utilized due to time constraints. From a logical standpoint, special relativity is important in satellite communications and in cosmology, as well as in modern physics applications such as atomic theory and high-energy physics. The purpose of this paper is to show that the new philosophy can be carried out in a noncalculus physics course, by demonstrating that all of the principal results of special relativity theory can be obtained by simple algebra. To accomplish this, we shall propose alternate derivations for two results that are usually obtained with calculus. Textbooks2 typically obtain the equations for time dilation and for length contraction from simple considerations based on Einstein's second postulate.3 We shall start from this point.

Carbachol-induced volume adaptation in mouse bladder and length adaptation via rhythmic contraction in rabbit detrusor.

PubMed

Speich, John E; Wilson, Cameron W; Almasri, Atheer M; Southern, Jordan B; Klausner, Adam P; Ratz, Paul H

2012-10-01

The length-tension (L-T) relationships in rabbit detrusor smooth muscle (DSM) are similar to those in vascular and airway smooth muscles and exhibit short-term length adaptation characterized by L-T curves that shift along the length axis as a function of activation and strain history. In contrast to skeletal muscle, the length-active tension (L-T(a)) curve for rabbit DSM strips does not have a unique peak tension value with a single ascending and descending limb. Instead, DSM can exhibit multiple ascending and descending limbs, and repeated KCl-induced contractions at a particular muscle length on an ascending or descending limb display increasingly greater tension. In the present study, mouse bladder strips with and without urothelium exhibited KCl-induced and carbachol-induced length adaptation, and the pressure-volume relationship in mouse whole bladder displayed short-term volume adaptation. Finally, prostaglandin-E(2)-induced low-level rhythmic contraction produced length adaptation in rabbit DSM strips. A likely role of length adaptation during bladder filling is to prepare DSM cells to contract efficiently over a broad range of volumes. Mammalian bladders exhibit spontaneous rhythmic contraction (SRC) during the filling phase and SRC is elevated in humans with overactive bladder (OAB). The present data identify a potential physiological role for SRC in bladder adaptation and motivate the investigation of a potential link between short-term volume adaptation and OAB with impaired contractility.

[Imprints of coronary plaque particles in the PTCA balloon surface during the dilatation processing].

PubMed

Werner, D; Behrend, D; Schmitz, K P; Urbaszek, W

1995-05-01

Seventy-six PTCA-balloons after coronary angioplasty were studied for superficial changes using scanning electron microscopy (SEM) after fixing in glutardialdehyde. Coronary plaque particles were identified on the balloon surface in 52 cases (68%). Twelve new and unused balloons were subjected to the same chemical treatment and SEM showed no imprints. The average length of the longest imprinted plaques was 128 +/- 201 microns and the average number of plaque particles per balloon was 4.9 +/- 2.7. The maximal dilatation pressure and the number of dilatations showed no influence on the impregnation of plaque particles. However, longer plaque imprints tended to occur under low dilatation pressure. Imprints of plaque particles were significantly higher in patients with low cholesterol (p = 0.0001) and low triglycerides (p = 0.0016). No correlation was seen between imprint length and lipid levels. Similarly, the different balloon materials (polyethylene, polyolefincopolymer) showed no significant differences with regard to plaque occurrence. The PTCA-balloons, plaque particles and six coronary plaques obtained after endatherectomy were subjected to energy dispersive x-ray analysis (EDX) under SEM as EDX reveals qualitative and quantitative information about the structural elements. Highly significant differences in calcium, sodium, phosphorus and silicon contents (p = 0.0000) between plaque particles and balloon surface were observed, owing to the absence of these in balloon material. Thus EDX offers additional advantages over SEM in that it clearly differentiates deformed balloon surface, plaque particle, and retained contrast medium. Plaque particles can be recovered from balloon surfaces after PTCA. Depending upon their size, they could lead to coronary spasm or microembolic phenomenon.

Laparoscopic Heller myotomy provides durable relief from achalasia and salvages failures after botox or dilation.

PubMed

Rosemurgy, Alexander; Villadolid, Desiree; Thometz, Donald; Kalipersad, Candice; Rakita, Steven; Albrink, Michael; Johnson, Milton; Boyce, Worth

2005-05-01

To report outcome after laparoscopic Heller myotomy in a large number of patients. Laparoscopic Heller myotomy has been undertaken for over a decade, but most studies involve small numbers of patients with limited follow-up. Since 1992, 262 patients have undergone laparoscopic Heller myotomy and been prospectively followed. Concomitant fundoplication was undertaken for a patulous hiatus or large hiatal hernia or to buttress the repair of an esophagotomy until recently when it became routinely applied. With mean follow-up at 32 months, symptoms were scored by patients on a Likert scale (frequency: 0 = Never to 10 = Every time I eat/always; severity: 0 = Not bothersome to 10 = Very bothersome). Before myotomy, 79% received Botox or bag dilation: 52% had Botox, 59% underwent dilation, and 36% had both. Inadvertent esophagotomy occurred in 5%. Concomitant diverticulectomy was undertaken in 4%, and fundoplication was undertaken in 30%. Complications were infrequent. Median length of stay was 1 day. After myotomy, the frequency and severity of symptoms of achalasia and reflux significantly decreased. Eighty-eight percent of patients felt their symptoms were greatly improved or resolved, and 90% felt their outcome was satisfying or better. Ninety-three percent felt they would undergo myotomy again, if necessary. Laparoscopic Heller myotomy can safely and durably relieve symptoms of dysphagia while also reducing symptoms of reflux. Length of stay is short and patient satisfaction is very high with extended follow-up. Laparoscopic Heller myotomy is strongly encouraged for patients with symptomatic achalasia and is efficacious even after failures of dilation and/or Botox therapy.

Determination of Prognostic Factors for Vaginal Mucosal Toxicity Associated With Intravaginal High-Dose Rate Brachytherapy in Patients With Endometrial Cancer

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

Bahng, Agnes Y.; Dagan, Avner; Bruner, Deborah W.

2012-02-01

Purpose: The objective of this study was to determine the patient- and treatment-related prognostic factors associated with vaginal toxicity in patients who received intravaginal high dose rate (HDR) brachytherapy alone as adjuvant treatment for endometrial cancer. Secondary goals of this study included a quantitative assessment of optimal dilator use frequency and a crude assessment of clinical predictors for compliant dilator use. Methods and Materials: We retrospectively reviewed the charts of 100 patients with histologically confirmed endometrial cancer who underwent total hysterectomy and bilateral salpingo-oophorectomy with or without lymph node dissection and adjuvant intravaginal brachytherapy between 1995 and 2009 at themore » Hospital of University of Pennsylvania. The most common treatment regimen used was 21 Gy in three fractions (71 patients). Symptoms of vaginal mucosal toxicity were taken from the history and physical exams noted in the patients' charts and were graded according to the Common Toxicity Criteria for Adverse Events v. 4.02. Results: The incidence of Grade 1 or asymptomatic vaginal toxicity was 33% and Grade 2-3 or symptomatic vaginal toxicity was 14%. Multivariate analysis of age, active length, and dilator use two to three times a week revealed odds ratios of 0.93 (p = 0.013), 3.96 (p = 0.008), and 0.17 (p = 0.032) respectively. Conclusion: Increasing age, vaginal dilator use of at least two to three times a week, and shorter active length were found to be significantly associated with a decreased risk of vaginal stenosis. Future prospective studies are necessary to validate our findings.« less

Effects of Step Length, Age, and Fall History on Hip and Knee Kinetics and Knee Co-contraction during the Maximum Step Length Test

PubMed Central

Schulz, Brian W.; Jongprasithporn, Manutchanok; Hart-Hughes, Stephanie J.; Bulat, Tatjana

2017-01-01

Background Maximum step length is a brief clinical test involving stepping out and back as far as possible with the arms folded across the chest. This test has been shown to predict fall risk, but the biomechanics of this test are not fully understood. Knee and hip kinetics (moments and powers) are greater for longer steps and for younger subjects, but younger subjects also step farther. Methods To separate effects of step length, age, and fall history on joint kinetics; 14 healthy younger, 14 older non-fallers, and 11 older fallers (27(5), 72(5), 75(6) years respectively) all stepped to the same relative target distances of 20-80% of their height. Knee and hip kinetics and knee co-contraction were calculated. Findings Hip and knee kinetics and knee co-contraction all increased with step length, but older non-fallers and fallers utilized greater stepping hip and less stepping knee extensor kinetics. Fallers had greater stepping knee co-contraction than non-fallers. Stance knee co-contraction of non-fallers was similar to young for shorter steps and similar to fallers for longer steps. Interpretation Age had minimal effects and fall history had no effects on joint kinetics of steps to similar distances. Effects of age and fall history on knee co-contraction may contribute to age-related kinetic differences and shorter maximal step lengths of older non-fallers and fallers, but step length correlated with every variable tested. Thus, declines in maximum step length could indicate declines in hip and knee extensor kinetics and impaired performance on similar tasks like recovering from a trip. PMID:23978310

Diverse effects of a 445 nm diode laser on isometric contraction of the rat aorta

PubMed Central

Park, Sang Woong; Shin, Kyung Chul; Park, Hyun Ji; Lee, In Wha; Kim, Hyung-Sik; Chung, Soon-Cheol; Kim, Ji-Sun; Jun, Jae-Hoon; Kim, Bokyung; Bae, Young Min

2015-01-01

The usefulness of visible lasers in treating vascular diseases is controversial. It is probable that multiple effects of visible lasers on blood vessels and their unclear mechanisms have hampered the usefulness of this therapy. Therefore, elucidating the precise actions and mechanisms of the effects of lasers on blood vessels would provide insight into potential biomedical applications. Here, using organ chamber isometric contraction measurements, western blotting, patch-clamp, and en face immunohistochemistry, we showed that a 445 nm diode laser contracted rat aortic rings, both by activating endothelial nitric oxide synthase and by increasing oxidative stress. In addition to the effects on the endothelium, the laser also directly relaxed and contracted vascular smooth muscle by inhibiting L-type Ca2+ channels and by activating protein tyrosine kinases, respectively. Thus, we conclude that exposure to 445 nm laser might contract and dilate blood vessels in the endothelium and smooth muscle via distinct mechanisms. PMID:26417517

In vitro smooth muscle contractility before and after relief of experimental obstruction in the rat: application to the surgical management of ileal dilatation.

PubMed

Haraux, Elodie; Canarelli, Jean-Pierre; Khorsi, Hafida; Delanaud, Stéphane; Bach, Véronique; Gay-Quéheillard, Jérome

2014-03-01

Bowel dilatation occurs proximal to an obstruction and predisposes to intestinal dysmotility. The present study sought to determine whether or not changes in smooth muscle contractility and the thickness of the proximal, dilated bowel wall can be reversed following relief of the obstruction. Three groups of seven male Wistar rats were studied. In 8-week-old animals in a control group and a sham-operated group, a small segment of bowel (designated as R1 for controls and R2 for shams) was resected 5.0 cm from the cecum. In the third (operated) group, a narrow, isoperistaltic intestinal loop was created proximal to an end-to-end anastomosis of the ileum in 4-week-old animals. When these animals were 6 weeks old, the loop was re-anastomosed to the distal small bowel (after resection of the loop's distal portion, referred to as R3). Two weeks later, a small segment of bowel was resected proximal to the anastomosis (R4). We evaluated the thickness of the smooth muscle layers and the in vitro contractile responses of circular smooth muscle ileal strips (R1-R4) to electrical stimulation and pharmacological stimulation (with KCl, acetylcholine (ACh), substance P, N(G)-nitro-l-arginine methyl ester (L-NAME) and histamine). The amplitudes of contraction in response to electrical and Ach-mediated stimulation were higher for R3 than for R4 (P<0.001), R1 and R2 (both P<0.05). Compared with R1 and R2, the smooth muscle layer was three times as thick in R3 (P<0.001) and 2.5 times as thick in R4 (P<0.01). Our study provides evidence of the possible recovery of intestinal motility (in response to neurotransmitters involved in gut function) after the relief of an obstruction. If ileal motility can conceivably return to normal values, conservative surgical procedures in pediatric patients should be preferred (in order to leave a sufficient length of bowel and avoid short bowel syndrome). © 2013 Elsevier Inc. All rights reserved.

A New Alternative for Difficult Ureter in Adult Patients: No Need to Dilate Ureter via a Balloon or a Stent with the Aid of 4.5F Semirigid Ureteroscope.

PubMed

Söylemez, Haluk; Yıldırım, Kadir; Utangac, Mehmet Mazhar; Aydoğan, Tahsin Batuhan; Ezer, Mehmet; Atar, Murat

2016-06-01

To investigate the effectivity of 4.5F ultrathin ureteroscope (UT-URS) without any need for active or passive dilation in the treatment of adult patient population in whom ureteral orifices cannot be engaged using conventional URS. Among a total of 512 adult patients who had undergone URS between April 2012 and November 2015 in our department for diagnostic or therapeutic purposes, 43 (8.4%) patients required ureteral dilation because we could not engage ureteral orifice. In adult patients in whom we could not engage ureteral orifice with 7.5F and 8F semirigid URS, we tried to complete the operation using 4.5F UT-URS without resorting to dilation. Age and gender of the patients, indication for operation, stone size, location, operative times, laterality of stone(s), stone-free rates, length of hospital stay, and complications were recorded. Mean age of the patients was 34.5 ± 11.2 (21-66) years. The patients had undergone operations for ureteral stone (n = 39), unexplained hydronephrosis (n = 2), and ureteral stenosis (n = 2). Mean stone size was 8.2 ± 2.3 (4-18) mm. Mean operative time was 64.2 ± 13.5 minutes. In 37 of 39 patients, a complete stone-free rate (94.8%) was achieved. Mean length of hospital stay was 8.9 ± 5.8 hours. It has been demonstrated that in an adult patient population in whom ureteral orifices cannot be engaged using conventional URS, ureteral access could be achieved with 4.5F UT-URS without any need for dilation. At the same time, use of 4.5F UT-URS resulted in an acceptable treatment success and lower complication rates in most of these patients without the need for a second session.

Dependence of displacement-length scaling relations for fractures and deformation bands on the volumetric changes across them

USGS Publications Warehouse

Schultz, R.A.; Soliva, R.; Fossen, H.; Okubo, C.H.; Reeves, D.M.

2008-01-01

Displacement-length data from faults, joints, veins, igneous dikes, shear deformation bands, and compaction bands define two groups. The first group, having a power-law scaling relation with a slope of n = 1 and therefore a linear dependence of maximum displacement and discontinuity length (Dmax = ??L), comprises faults and shear (non-compactional or non-dilational) deformation bands. These shearing-mode structures, having shearing strains that predominate over volumetric strains across them, grow under conditions of constant driving stress, with the magnitude of near-tip stress on the same order as the rock's yield strength in shear. The second group, having a power-law scaling relation with a slope of n = 0.5 and therefore a dependence of maximum displacement on the square root of discontinuity length (Dmax = ??L0.5), comprises joints, veins, igneous dikes, cataclastic deformation bands, and compaction bands. These opening- and closing-mode structures grow under conditions of constant fracture toughness, implying significant amplification of near-tip stress within a zone of small-scale yielding at the discontinuity tip. Volumetric changes accommodated by grain fragmentation, and thus control of propagation by the rock's fracture toughness, are associated with scaling of predominantly dilational and compactional structures with an exponent of n = 0.5. ?? 2008 Elsevier Ltd.

Two-Phase Solid/Fluid Simulation of Dense Granular Flows With Dilatancy Effects

NASA Astrophysics Data System (ADS)

Mangeney, A.; Bouchut, F.; Fernández-Nieto, E. D.; Kone, E. H.; Narbona-Reina, G.

2016-12-01

Describing grain/fluid interaction in debris flows models is still an open and challenging issue with key impact on hazard assessment [1]. We present here a two-phase two-thin-layer model for fluidized debris flows that takes into account dilatancy effects. It describes the velocity of both the solid and the fluid phases, the compression/ dilatation of the granular media and its interaction with the pore fluid pressure [2]. The model is derived from a 3D two-phase model proposed by Jackson [3] and the mixture equations are closed by a weak compressibility relation. This relation implies that the occurrence of dilation or contraction of the granular material in the model depends on whether the solid volume fraction is respectively higher or lower than a critical value. When dilation occurs, the fluid is sucked into the granular material, the pore pressure decreases and the friction force on the granular phase increases. On the contrary, in the case of contraction, the fluid is expelled from the mixture, the pore pressure increases and the friction force diminishes. To account for this transfer of fluid into and out of the mixture, a two-layer model is proposed with a fluid or a solid layer on top of the two-phase mixture layer. Mass and momentum conservation are satisfied for the two phases, and mass and momentum are transferred between the two layers. A thin-layer approximation is used to derive average equations. Special attention is paid to the drag friction terms that are responsible for the transfer of momentum between the two phases and for the appearance of an excess pore pressure with respect to the hydrostatic pressure. By comparing quantitatively the results of simulation and laboratory experiments on submerged granular flows, we show that our model contains the basic ingredients making it possible to reproduce the interaction between the granular and fluid phases through the change in pore fluid pressure. In particular, we analyse the different time scales in the model and their role in granular/fluid flow dynamics. References[1] R. Delannay, A. Valance, A. Mangeney, O. Roche, P. Richard, J. Phys. D: Appl. Phys., in press (2016). [2] F. Bouchut, E. D. Fernández-Nieto, A. Mangeney, G. Narbona-Reina, J. Fluid Mech., 801, 166-221 (2016). [3] R. Jackson, Cambridges Monographs on Mechanics (2000).

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2013-11-08

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30 CFR 1206.114 - What are my reporting requirements under an arm's-length transportation contract?

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 3 2011-07-01 2011-07-01 false What are my reporting requirements under an arm... VALUATION Federal Oil § 1206.114 What are my reporting requirements under an arm's-length transportation... submit arm's-length transportation contracts, production agreements, operating agreements, and related...

Recruitment of single human low-threshold motor units with increasing loads at different muscle lengths.

PubMed

McNulty, P A; Cresswell, A G

2004-06-01

We investigated the recruitment behaviour of low threshold motor units in flexor digitorum superficialis by altering two biomechanical constraints: the load against which the muscle worked and the initial muscle length. The load was increased using isotonic (low load), loaded dynamic (intermediate load) and isometric (high load) contractions in two studies. The initial muscle position reflected resting muscle length in series A, and a longer length with digit III fully extended in series B. Intramuscular EMG was recorded from 48 single motor units in 10 experiments on five healthy subjects, 21 units in series A and 27 in series B, while subjects performed ramp up, hold and ramp down contractions. Increasing the load on the muscle decreased the force, displacement and firing rate of single motor units at recruitment at shorter muscle lengths (P<0.001, dependent t-test). At longer muscle lengths this recruitment pattern was observed between loaded dynamic and isotonic contractions, but not between isometric and loaded dynamic contractions. Thus, the recruitment properties of single motor units in human flexor digitorum superficialis are sensitive to changes in both imposed external loads and the initial length of the muscle.

'X-ray'-free balloon dilation for totally ultrasound-guided percutaneous nephrolithotomy.

PubMed

Zhou, Tie; Chen, Guanghua; Gao, Xiaofeng; Zhang, Wei; Xu, Chuanliang; Li, Lei; Sun, Yinghao

2015-04-01

The objective of the study was to evaluate the feasibility and safety of balloon dilation for 'X-ray'-free ultrasound-guided percutaneous nephrolithotomy (PCNL). From January 2012 to December 2012, patients underwent 'X-ray'-free ultrasound-guided PCNL with Amplatz dilator (Group A). From January 2013 to April 2014, patients underwent 'X-ray'-free ultrasound-guided PCNL with balloon dilator (Group B). For balloon dilation, a 10 F fascial dilator was used to dilate the tract. Subsequently, the 6 F nephrostomy balloon (8 mm in diameter) was indwelled along the guidewire with a marked length equal to the dilation depth. Under the monitoring of ultrasound, the location of balloon was secured and disappearance of balloon waist was confirmed when the balloon was inflated at a pressure of 20 atm. A total of 163 patients were involved in this study. Of 81 procedures in Group A, 45 procedures were performed by a senior urologist while 36 procedures by a resident. Of 82 patients in Group B, 47 procedures were performed by the same senior urologist while 35 procedures by another resident. For the senior urologist, there was no statistically significant difference between two groups in calyx of entry, stone-free rate, decline of hemoglobin and hematocrit, operation time and hospitalization. But for the residents, there was less decline of hemoglobin and hematocrit, tract development time and hospitalization in Group B compared to Group A (0.6 vs. 1.7 g/dl, p = 0.001; 2.3% vs. 5.5%, p = 0.003; 10.1 vs. 11.0 min, p = 0.027; 7.8 vs. 13.9 days, p < 0.001). Balloon dilation method introduced in this study is compensable for tract development when 'X-ray'-free ultrasound-guided PCNL is performed. Modified techniques make totally ultrasound guidance for PCNL feasible, easy and safe. In addition, such a procedure is preferable for initial operators because of less hemorrhage complication.

Optimal design of vertebrate and insect sarcomeres.

PubMed

Otten, E

1987-01-01

This paper offers a model for the normalized length-tension relation of a muscle fiber based upon sarcomere design. Comparison with measurements published by Gordon et al. ('66) shows an accurate fit as long as the inhomogeneity of sarcomere length in a single muscle fiber is taken into account. Sequential change of filament length and the length of the cross-bridge-free zone leads the model to suggest that most vertebrate sarcomeres tested match the condition of optimal construction for the output of mechanical energy over a full sarcomere contraction movement. Joint optimization of all three morphometric parameters suggests that a slightly better (0.3%) design is theoretically possible. However, this theoretical sarcomere, optimally designed for the conversion of energy, has a low normalized contraction velocity; it provides a poorer match to the combined functional demands of high energy output and high contraction velocity than the real sarcomeres of vertebrates. The sarcomeres in fish myotomes appear to be built suboptimally for isometric contraction, but built optimally for that shortening velocity generating maximum power. During swimming, these muscles do indeed contract concentrically only. The sarcomeres of insect asynchronous flight muscles contract only slightly. They are not built optimally for maximum output of energy across the full range of contraction encountered in vertebrate sarcomeres, but are built almost optimally for the contraction range that they do in fact employ.

Tendon Contraction After Cyclic Elongation Is an Age-Dependent Phenomenon: In Vitro and In Vivo Comparisons.

PubMed

Lavagnino, Michael; Bedi, Asheesh; Walsh, Christopher P; Sibilsky Enselman, Elizabeth R; Sheibani-Rad, Shahin; Arnoczky, Steven P

2014-06-01

Tendons are viscoelastic tissues that deform (elongate) in response to cyclic loading. However, the ability of a tendon to recover this elongation is unknown. Tendon length significantly increases after in vivo or in vitro cyclic loading, and the ability to return to its original length through a cell-mediated contraction mechanism is an age-dependent phenomenon. Controlled laboratory study. In vitro, rat tail tendon fascicles (RTTfs) from Sprague-Dawley rats of 3 age groups (1, 3, and 12 months) underwent 2% cyclic strain at 0.17 Hz for 2 hours, and the percentages of elongation were determined. After loading, the RTTfs were suspended for 3 days under tissue culture conditions and photographed daily to determine the amount of length contraction. In vivo, healthy male participants (n = 29; age, 19-49 years) had lateral, single-legged weightbearing radiographs taken of the knee at 60° of flexion immediately before, immediately after, and 24 hours after completing eccentric quadriceps loading exercises on the dominant leg to fatigue. Measurements of patellar tendon length were taken from the radiographs, and the percentages of tendon elongation and subsequent contraction were calculated. In vitro, cyclic loading increased the length of all RTTfs, with specimens from younger (1 and 3 months) rats demonstrating significantly greater elongation than those from older (12 months) rats (P = .009). The RTTfs contracted to their original length significantly faster (P < .001) and in an age-dependent fashion, with younger animals contracting faster. In vivo, repetitive eccentric loading exercises significantly increased patellar tendon length (P < .001). Patellar tendon length decreased 24 hours after exercises (P < .001) but did not recover completely (P < .001). There was a weak but significant (R (2) = 0.203, P = .014) linear correlation between the amount of tendon contraction and age, with younger participants (<30 years) demonstrating significantly more contraction (P = .014) at 24 hours than older participants (>30 years). Cyclic tendon loading results in a significant increase in tendon elongation under both in vitro and in vivo conditions. Tendons in both conditions demonstrated an incomplete return to their original length after 24 hours, and the extent of this return was age dependent. The age- and time-dependent contraction of tendons, elongated after repetitive loading, could result in transient alterations in the mechanobiological environment of tendon cells. This, in turn, could induce the onset of catabolic changes associated with the pathogenesis of tendinopathy. These results suggest the importance of allowing time for contraction between bouts of repetitive exercise and may explain why age is a predisposing factor in tendinopathy. © 2014 The Author(s).

Calculation of contraction stresses in dental composites by analysis of crack propagation in the matrix surrounding a cavity.

PubMed

Yamamoto, Takatsugu; Ferracane, Jack L; Sakaguchi, Ronald L; Swain, Michael V

2009-04-01

Polymerization contraction of dental composite produces a stress field in the bonded surrounding substrate that may be capable of propagating cracks from pre-existing flaws. The objectives of this study were to assess the extent of crack propagation from flaws in the surrounding ceramic substrate caused by composite contraction stresses, and to propose a method to calculate the contraction stress in the ceramic using indentation fracture. Initial cracks were introduced with a Vickers indenter near a cylindrical hole drilled into a glass-ceramic simulating enamel. Lengths of the radial indentation cracks were measured. Three composites having different contraction stresses were cured within the hole using one- or two-step light-activation methods and the crack lengths were measured. The contraction stress in the ceramic was calculated from the crack length and the fracture toughness of the glass-ceramic. Interfacial gaps between the composite and the ceramic were expressed as the ratio of the gap length to the hole perimeter, as well as the maximum gap width. All groups revealed crack propagation and the formation of contraction gaps. The calculated contraction stresses ranged from 4.2 MPa to 7.0 MPa. There was no correlation between the stress values and the contraction gaps. This method for calculating the stresses produced by composites is a relatively simple technique requiring a conventional hardness tester. The method can investigate two clinical phenomena that may occur during the placement of composite restorations, i.e. simulated enamel cracking near the margins and the formation of contraction gaps.

A pseudo-sound constitutive relationship for the dilatational covariances in compressible turbulence: An analytical theory

NASA Technical Reports Server (NTRS)

Ristorcelli, J. R.

1995-01-01

The mathematical consequences of a few simple scaling assumptions about the effects of compressibility are explored using a simple singular perturbation idea and the methods of statistical fluid mechanics. Representations for the pressure-dilation and dilatational dissipation covariances appearing in single-point moment closures for compressible turbulence are obtained. While the results are expressed in the context of a second-order statistical closure they provide some interesting and very clear physical metaphors for the effects of compressibility that have not been seen using more traditional linear stability methods. In the limit of homogeneous turbulence with quasi-normal large-scales the expressions derived are - in the low turbulent Mach number limit - asymptotically exact. The expressions obtained are functions of the rate of change of the turbulence energy, its correlation length scale, and the relative time scale of the cascade rate. The expressions for the dilatational covariances contain constants which have a precise and definite physical significance; they are related to various integrals of the longitudinal velocity correlation. The pressure-dilation covariance is found to be a nonequilibrium phenomena related to the time rate of change of the internal energy and the kinetic energy of the turbulence. Also of interest is the fact that the representation for the dilatational dissipation in turbulence, with or without shear, features a dependence on the Reynolds number. This article is a documentation of an analytical investigation of the implications of a pseudo-sound theory for the effects of compressibility.

30 CFR 1206.114 - What are my reporting requirements under an arm's-length transportation contract?

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 3 2014-07-01 2014-07-01 false What are my reporting requirements under an arm....114 What are my reporting requirements under an arm's-length transportation contract? You or your... costs you or your affiliate incur. ONRR may require you or your affiliate to submit arm's-length...

30 CFR 1206.114 - What are my reporting requirements under an arm's-length transportation contract?

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 3 2013-07-01 2013-07-01 false What are my reporting requirements under an arm....114 What are my reporting requirements under an arm's-length transportation contract? You or your... costs you or your affiliate incur. ONRR may require you or your affiliate to submit arm's-length...

30 CFR 206.114 - What are my reporting requirements under an arm's-length transportation contract?

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 2 2010-07-01 2010-07-01 false What are my reporting requirements under an arm... What are my reporting requirements under an arm's-length transportation contract? You or your affiliate... you or your affiliate incur. MMS may require you or your affiliate to submit arm's-length...

30 CFR 1206.114 - What are my reporting requirements under an arm's-length transportation contract?

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 3 2012-07-01 2012-07-01 false What are my reporting requirements under an arm....114 What are my reporting requirements under an arm's-length transportation contract? You or your... costs you or your affiliate incur. ONRR may require you or your affiliate to submit arm's-length...

Relativistic Length Agony Continued

NASA Astrophysics Data System (ADS)

Redzic, D. V.

2014-06-01

We made an attempt to remedy recent confusing treatments of some basic relativistic concepts and results. Following the argument presented in an earlier paper (Redzic 2008b), we discussed the misconceptions that are recurrent points in the literature devoted to teaching relativity such as: there is no change in the object in Special Relativity, illusory character of relativistic length contraction, stresses and strains induced by Lorentz contraction, and related issues. We gave several examples of the traps of everyday language that lurk in Special Relativity. To remove a possible conceptual and terminological muddle, we made a distinction between the relativistic length reduction and relativistic FitzGerald-Lorentz contraction, corresponding to a passive and an active aspect of length contraction, respectively; we pointed out that both aspects have fundamental dynamical contents. As an illustration of our considerations, we discussed briefly the Dewan-Beran-Bell spaceship paradox and the 'pole in a barn' paradox.

Predictors of short term treatment outcome in patients with achalasia following endoscopic or surgical therapy.

PubMed

Gheorghe, Cristian; Bancila, Ion; Tutuian, Radu; Iacob, Razvan; Tomulescu, Victor

2012-01-01

Pneumatic balloon dilation and surgical myotomy are the most effective treatments for achalasia. While there is controversy which method is best, the aim of the current study was to identify predictors of symptom recurrence after endoscopic or surgical therapy. Patients undergoing pneumatic balloon dilatation (30mm) or laparoscopic Heller myotomy with Dor fundoplication were included in the study. Analyzed parameters include total symptom score (sum of 0-5 point intensity for dysphagia, regurgitation and chest pain), width and height of esophageal column at 2 and 5 minutes after oral barium ingestion, lower esophageal sphincter (LES) length, resting (LESP) and residual pressure (LESRP) before and 3 months after intervention. Patients with symptoms score <3 at the 3-month follow-up visit were considered asymptomatic. Twenty-one patients underwent pneumatic dilation (14) or laparoscopic myotomy (7). Total symptom score improved (p<0.01) from pre- (7.2±2.7) to post-intervention (1.7±2.6). Eleven (85.8%) patients in the endoscopic group vs. 7 (100%) patients in the surgical group were symptom-free 3 months after intervention. Therapies improved LESP (24.4±8.2mmHg pre- vs. 15.4±10.3mmHg post-therapy; p=0.003) and mean LESRP (7.9±4.3mmHg pre- vs. 5.3±6.7mmHg post-therapy; p=0.03). Univariate linear regression analysis identified barium contrast column width >5cm at 2 minutes (p=0.04), LES length <2cm (p=0.003) and LESRP >10mmHg (p=0.02) as predictors for persistent symptoms. While >85% of achalasia patients responded well to 30mm pneumatic balloon dilation, patients with elevated LES pressure, short LES and wide esophagus should be considered as primary surgical candidates.

Laparoscopic Heller Myotomy Provides Durable Relief From Achalasia and Salvages Failures After Botox or Dilation

PubMed Central

Rosemurgy, Alexander; Villadolid, Desiree; Thometz, Donald; Kalipersad, Candice; Rakita, Steven; Albrink, Michael; Johnson, Milton; Boyce, Worth

2005-01-01

Objective: To report outcome after laparoscopic Heller myotomy in a large number of patients. Summary Background Data: Laparoscopic Heller myotomy has been undertaken for over a decade, but most studies involve small numbers of patients with limited follow-up. Methods: Since 1992, 262 patients have undergone laparoscopic Heller myotomy and been prospectively followed. Concomitant fundoplication was undertaken for a patulous hiatus or large hiatal hernia or to buttress the repair of an esophagotomy until recently when it became routinely applied. With mean follow-up at 32months, symptoms were scored by patients on a Likert scale (frequency: 0 = Never to 10 = Every time I eat/always; severity: 0 = Not bothersome to 10 = Very bothersome). Results: Before myotomy, 79% received Botox or bag dilation: 52% had Botox, 59% underwent dilation, and 36% had both. Inadvertent esophagotomy occurred in 5%. Concomitant diverticulectomy was undertaken in 4%, and fundoplication was undertaken in 30%. Complications were infrequent. Median length of stay was 1 day. After myotomy, the frequency and severity of symptoms of achalasia and reflux significantly decreased. Eighty-eight percent of patients felt their symptoms were greatly improved or resolved, and 90% felt their outcome was satisfying or better. Ninety-three percent felt they would undergo myotomy again, if necessary. Conclusions: Laparoscopic Heller myotomy can safely and durably relieve symptoms of dysphagia while also reducing symptoms of reflux. Length of stay is short and patient satisfaction is very high with extended follow-up. Laparoscopic Heller myotomy is strongly encouraged for patients with symptomatic achalasia and is efficacious even after failures of dilation and/or Botox therapy. PMID:15849508

Quantitative mRNA analysis of muscarinic acetylcholine receptors in the intestine of dairy cows with spontaneous caecal dilatation-dislocation.

PubMed

Ontsouka, E C; Steiner, A; Bruckmaier, R M; Blum, J W; Meylan, M

2009-05-01

Muscarinic receptors mediate acetylcholine-induced muscular contractions. In this study, mRNA levels of muscarinic receptor subtypes 2 and 3 (M(2) and M(3)) in the ileum, caecum, proximal loop of the ascending colon (PLAC) and external loop of the spiral colon (ELSC) were determined by quantitative polymerase chain reaction in seven cows with caecal dilatation-dislocation (CDD) and seven healthy control cows. Levels of M(2) were significantly lower in the caecum, PLAC and ELSC and levels of M(3) were significantly lower in the ileum, caecum, PLAC and ELSC of cows with CDD compared to healthy cows (P<0.05). Down-regulation of M(3) may play a role in the pathogenesis of CDD.

Adaptation of the length-active tension relationship in rabbit detrusor

PubMed Central

Almasri, Atheer M.; Bhatia, Hersch; Klausner, Adam P.; Ratz, Paul H.

2009-01-01

Studies have shown that the length-tension (L-T) relationships in airway and vascular smooth muscles are dynamic and can adapt to length changes over a period of time. Our prior studies have shown that the passive L-T relationship in rabbit detrusor smooth muscle (DSM) is also dynamic and that DSM exhibits adjustable passive stiffness (APS) characterized by a passive L-T curve that can shift along the length axis as a function of strain history and activation history. The present study demonstrates that the active L-T curve for DSM is also dynamic and that the peak active tension produced at a particular muscle length is a function of both strain and activation history. More specifically, this study reveals that the active L-T relationship, or curve, does not have a unique peak tension value with a single ascending and descending limb, but instead reveals that multiple ascending and descending limbs can be exhibited in the same DSM strip. This study also demonstrates that for DSM strips not stretched far enough to reveal a descending limb, the peak active tension produced by a maximal KCl-induced contraction at a short, passively slack muscle length of 3 mm was reduced by 58.6 ± 4.1% (n = 15) following stretches to and contractions at threefold the original muscle length, 9 mm. Moreover, five subsequent contractions at the short muscle length displayed increasingly greater tension; active tension produced by the sixth contraction was 91.5 ± 9.1% of that produced by the prestretch contraction at that length. Together, these findings indicate for the first time that DSM exhibits length adaptation, similar to vascular and airway smooth muscles. In addition, our findings demonstrate that preconditioning, APS and adaptation of the active L-T curve can each impact the maximum total tension observed at a particular DSM length. PMID:19675182

In vivo fascicle length measurements via B-mode ultrasound imaging with single vs dual transducer arrangements.

PubMed

Brennan, Scott F; Cresswell, Andrew G; Farris, Dominic J; Lichtwark, Glen A

2017-11-07

Ultrasonography is a useful technique to study muscle contractions in vivo, however larger muscles like vastus lateralis may be difficult to visualise with smaller, commonly used transducers. Fascicle length is often estimated using linear trigonometry to extrapolate fascicle length to regions where the fascicle is not visible. However, this approach has not been compared to measurements made with a larger field of view for dynamic muscle contractions. Here we compared two different single-transducer extrapolation methods to measure VL muscle fascicle length to a direct measurement made using two synchronised, in-series transducers. The first method used pennation angle and muscle thickness to extrapolate fascicle length outside the image (extrapolate method). The second method determined fascicle length based on the extrapolated intercept between a fascicle and the aponeurosis (intercept method). Nine participants performed maximal effort, isometric, knee extension contractions on a dynamometer at 10° increments from 50 to 100° of knee flexion. Fascicle length and torque were simultaneously recorded for offline analysis. The dual transducer method showed similar patterns of fascicle length change (overall mean coefficient of multiple correlation was 0.76 and 0.71 compared to extrapolate and intercept methods respectively), but reached different absolute lengths during the contractions. This had the effect of producing force-length curves of the same shape, but each curve was shifted in terms of absolute length. We concluded that dual transducers are beneficial for studies that examine absolute fascicle lengths, whereas either of the single transducer methods may produce similar results for normalised length changes, and repeated measures experimental designs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Does the Length of Elbow Flexors and Visual Feedback Have Effect on Accuracy of Isometric Muscle Contraction in Men after Stroke?

PubMed Central

Juodzbaliene, Vilma; Darbutas, Tomas; Skurvydas, Albertas

2016-01-01

The aim of the study was to determine the effect of different muscle length and visual feedback information (VFI) on accuracy of isometric contraction of elbow flexors in men after an ischemic stroke (IS). Materials and Methods. Maximum voluntary muscle contraction force (MVMCF) and accurate determinate muscle force (20% of MVMCF) developed during an isometric contraction of elbow flexors in 90° and 60° of elbow flexion were measured by an isokinetic dynamometer in healthy subjects (MH, n = 20) and subjects after an IS during their postrehabilitation period (MS, n = 20). Results. In order to evaluate the accuracy of the isometric contraction of the elbow flexors absolute errors were calculated. The absolute errors provided information about the difference between determinate and achieved muscle force. Conclusions. There is a tendency that greater absolute errors generating determinate force are made by MH and MS subjects in case of a greater elbow flexors length despite presence of VFI. Absolute errors also increase in both groups in case of a greater elbow flexors length without VFI. MS subjects make greater absolute errors generating determinate force without VFI in comparison with MH in shorter elbow flexors length. PMID:27042670

Dilated cardiomyopathy secondary to rickets-related hypocalcaemia: eight case reports and a review of the literature.

PubMed

Yilmaz, Osman; Olgun, Hasim; Ciftel, Murat; Kilic, Omer; Kartal, Ibrahim; Iskenderoglu, Nebahat Y; Laloglu, Fuat; Ceviz, Naci

2015-02-01

Dilated cardiomyopathy is usually idiopathic and may arise secondary to infections or metabolic or genetic causes. Another rare cause is hypocalcaemia. Owing to the fact that calcium plays an essential role in excitation and contraction of myocardial muscle, myocardial contractility may decline in patients with hypocalcaemia. Patients with symptoms of congestive heart failure and rickets-related hypocalcaemia were assessed clinically and by echocardiography in a paediatric cardiology clinic. Echocardiography was performed for all patients. Rickets was diagnosed according to the clinical, laboratory, and radiologic findings. Maternal lifestyle and living conditions were investigated, and the maternal 25-OH vitamin D3 blood level was measured. We evaluated eight patients who developed heart failure as a result of severe hypocalcaemia associated with rickets between August, 1999 and June, 2012. The age distribution of the patients was 3-12 months. Laboratory results were consistent with advanced-stage rickets. Severe hypocalcaemia was detected in all patients. The maternal 25-OH vitamin D3 levels were low. Echocardiography revealed increased pre-treatment left ventricle end-systolic and end-diastolic diameters for age and reduced ejection fraction and fractional shortening. After clinical improvement, the patients were discharged. Severe hypocalcaemia associated with rickets must always be kept in mind among the causes of dilated cardiomyopathy and impaired cardiac function in infants. If diagnosed and treated in time, dilated cardiomyopathy and severe heart failure related to rickets respond well.

Cardiomyocyte-Specific Ablation of Med1 Subunit of the Mediator Complex Causes Lethal Dilated Cardiomyopathy in Mice.

PubMed

Jia, Yuzhi; Chang, Hsiang-Chun; Schipma, Matthew J; Liu, Jing; Shete, Varsha; Liu, Ning; Sato, Tatsuya; Thorp, Edward B; Barger, Philip M; Zhu, Yi-Jun; Viswakarma, Navin; Kanwar, Yashpal S; Ardehali, Hossein; Thimmapaya, Bayar; Reddy, Janardan K

2016-01-01

Mediator, an evolutionarily conserved multi-protein complex consisting of about 30 subunits, is a key component of the polymerase II mediated gene transcription. Germline deletion of the Mediator subunit 1 (Med1) of the Mediator in mice results in mid-gestational embryonic lethality with developmental impairment of multiple organs including heart. Here we show that cardiomyocyte-specific deletion of Med1 in mice (csMed1-/-) during late gestational and early postnatal development by intercrossing Med1fl/fl mice to α-MyHC-Cre transgenic mice results in lethality within 10 days after weaning due to dilated cardiomyopathy-related ventricular dilation and heart failure. The csMed1-/- mouse heart manifests mitochondrial damage, increased apoptosis and interstitial fibrosis. Global gene expression analysis revealed that loss of Med1 in heart down-regulates more than 200 genes including Acadm, Cacna1s, Atp2a2, Ryr2, Pde1c, Pln, PGC1α, and PGC1β that are critical for calcium signaling, cardiac muscle contraction, arrhythmogenic right ventricular cardiomyopathy, dilated cardiomyopathy and peroxisome proliferator-activated receptor regulated energy metabolism. Many genes essential for oxidative phosphorylation and proper mitochondrial function such as genes coding for the succinate dehydrogenase subunits of the mitochondrial complex II are also down-regulated in csMed1-/- heart contributing to myocardial injury. Data also showed up-regulation of about 180 genes including Tgfb2, Ace, Atf3, Ctgf, Angpt14, Col9a2, Wisp2, Nppa, Nppb, and Actn1 that are linked to cardiac muscle contraction, cardiac hypertrophy, cardiac fibrosis and myocardial injury. Furthermore, we demonstrate that cardiac specific deletion of Med1 in adult mice using tamoxifen-inducible Cre approach (TmcsMed1-/-), results in rapid development of cardiomyopathy and death within 4 weeks. We found that the key findings of the csMed1-/- studies described above are highly reproducible in TmcsMed1-/- mouse heart. Collectively, these observations suggest that Med1 plays a critical role in the maintenance of heart function impacting on multiple metabolic, compensatory and reparative pathways with a likely therapeutic potential in the management of heart failure.

Characterization of the myometrial transcriptome in women with an arrest of dilatation during labor

PubMed Central

Chaemsaithong, Piya; Madan, Ichchha; Romero, Roberto; Than, Nandor G; Tarca, Adi L; Draghici, Sorin; Bhatti, Gaurav; Mazor, Moshe; Kim, Chong Jai; Hassan, Sonia S; Chaiworapongsa, Tinnakorn

2014-01-01

Objective The molecular basis of failure to progress in labor is poorly understood. This study was undertaken to characterize the myometrial transcriptome of patients with an arrest of dilatation (AODIL). Study design Human myometrium was prospectively collected from women in the following groups: 1) spontaneous term labor (TL; n=29); and 2) arrest of dilatation (AODIL; n=14). Gene expression was characterized using Illumina® HumanHT-12 microarrays. A moderated student t-test and false discovery rate adjustment were used for analysis. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) of selected genes was performed in an independent sample set. Pathway analysis was performed on the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway database using Pathway Analysis with Down-weighting of Overlapping Genes (PADOG). The Metacore knowledge base was also mined for pathway analysis. Results 1) 42 genes differentially expressed were identified in women with an AODIL; 2) gene ontology analysis indicated enrichment of biological processes, which included: regulation of angiogenesis, response to hypoxia, inflammatory response, and chemokine-mediated signaling pathway. Enriched molecular functions included: transcription repressor activity, Heat shock protein (Hsp) 90 binding, and nitric oxide synthase (NOS) activity; 3) Metacore analysis identified immune response chemokine (C-C motif) ligand 2 (CCL2) signaling, muscle contraction regulation of eNOS activity in endothelial cells, and Triiodothyronine and Thyroxine signaling as significantly over-represented (FDR<0.05); 4) qRT-PCR confirmed overexpression of Nitric oxide synthase 3 NOS3; hypoxic ischemic factor (HIF1A), Chemokine (C-C motif) ligand 2 (CCL2); angiopoietin-like 4 (ANGPTL4), ADAM metallopeptidase with thrombospondin type 1, motif 9 (ADAMTS9), G protein-coupled receptor 4 (GPR4), metallothionein 1A (MT1A), MT2A, selectin E (SELE) in an AODIL. Conclusion The myometrium of women with arrest of dilatation have a stereotypic transcriptome profile. This disorder was associated with a pattern of gene expression involved in muscle contraction, an inflammatory response, and hypoxia. This is the first comprehensive and unbiased examination of the molecular basis of an AODIL. PMID:23893668

Optical clocks and relativity.

PubMed

Chou, C W; Hume, D B; Rosenband, T; Wineland, D J

2010-09-24

Observers in relative motion or at different gravitational potentials measure disparate clock rates. These predictions of relativity have previously been observed with atomic clocks at high velocities and with large changes in elevation. We observed time dilation from relative speeds of less than 10 meters per second by comparing two optical atomic clocks connected by a 75-meter length of optical fiber. We can now also detect time dilation due to a change in height near Earth's surface of less than 1 meter. This technique may be extended to the field of geodesy, with applications in geophysics and hydrology as well as in space-based tests of fundamental physics.

Discrete linear canonical transforms based on dilated Hermite functions.

PubMed

Pei, Soo-Chang; Lai, Yun-Chiu

2011-08-01

Linear canonical transform (LCT) is very useful and powerful in signal processing and optics. In this paper, discrete LCT (DLCT) is proposed to approximate LCT by utilizing the discrete dilated Hermite functions. The Wigner distribution function is also used to investigate DLCT performances in the time-frequency domain. Compared with the existing digital computation of LCT, our proposed DLCT possess additivity and reversibility properties with no oversampling involved. In addition, the length of input/output signals will not be changed before and after the DLCT transformations, which is consistent with the time-frequency area-preserving nature of LCT; meanwhile, the proposed DLCT has very good approximation of continuous LCT.

30 CFR 1206.57 - Determination of transportation allowances.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Determination of transportation allowances... transportation allowances. (a) Arm's-length transportation contracts. (1)(i) For transportation costs incurred by a lessee under an arm's-length contract, the transportation allowance shall be the reasonable...

Dyssynchronous ventricular contraction in Wolff-Parkinson-White syndrome: a risk factor for the development of dilated cardiomyopathy.

PubMed

Dai, Chen-Cheng; Guo, Bao-Jing; Li, Wen-Xiu; Xiao, Yan-Yan; Jin, Mei; Han, Lin; Sun, Jing-Ping; Yu, Cheuk-Man; Dong, Jian-Zeng

2013-11-01

Emerging evidence suggests that significant left ventricular dysfunction may arise in right-sided septal or paraseptal accessory pathways (APs) with Wolff-Parkinson-White syndrome, even in the absence of recurrent or incessant tachycardia. During 1 year and 9 months, we identified four consecutive female children with median age of 8 years diagnosed as having dilated cardiomyopathy (DCM) combined with overt right-sided APs several years ago. Incessant or recurrent tachycardia as the cause of DCM could be excluded. Anti-heart failure chemotherapy did not produce satisfactory effects. The patients underwent radiofrequency ablations (RFCAs). This report describes the clinical and echocardiographic characteristics of the cases before and after the ablation. Dyssynchronous ventricular contraction was observed in all patients. The locations of the APs were the right-sided anteroseptum and the free wall (n = 2 each). All patients received successful RFCAs. Their physical activities and growth improved greatly, and the echocardiographic data demonstrated that their left ventricular (LV) contraction recovered to synchrony shortly after the ablation and that their LV function recovered to normal gradually during the follow-up. A causal relationship between overt ventricular preexcitation and the development of DCM is supported by the complete recovery of LV function and reversed LV remodeling after the loss of ventricular preexcitation. Preexcitation-related dyssynchrony was probably the crucial mechanism. Not only right-sided septal or paraseptal but also free wall overt APs may induce LV dysfunction and even DCM. AP-induced DCM is an indication for ablation with a good prognosis.

[Combination of the ureteral dilation catheter and balloon catheter under the ureteroscope in the treatment of male urethral stricture].

PubMed

Zhou, Yi; Li, Gong-hui; Yan, Jia-jun; Shen, Cong; Tang, Gui-hang; Xu, Gang

2016-01-01

To investigate the clinical application of the ureteral dilation catheter combined with the balloon catheter under the ureteroscope in the treatment of urethral stricture in men. Under the ureteroscope, 45 male patients with urethral stricture received placement of a zebra guide wire through the strictured urethra into the bladder and then a ureteral dilation catheter along the guide wire, followed by dilation of the urethra from F8 initially to F14 and F16. Again, the ureteroscope was used to determine the length of the strictured urethra, its distance to the external urethral orifice, and whether it was normally located. An F24 balloon catheter and then a metal urethral calibrator was used for the dilation of the strictured urethra. After removal of the F18-F22 urethral catheter at 8 weeks, the urinary flow rate was measured immediately and again at 3 months. All the operations were successfully performed without serious complications. The maximum urinary flow rate was (13.3-29.9) ml/s (mean [17.7 ± 3.2] ml/s) at the removal of the catheter and (15.2-30.8) ml/s (mean [19.8 ± 3.9] ml/s) at 3 months after it. Smooth urination was found in all the patients during the 6-24 months follow-up. The application of the ureteral dilation catheter combined with, the balloon catheter under the ureteroscope is a good option for the treatment of male urethral stricture for its advantages of uncomplicatedness, safety, effectiveness, few complications, less pain, high success rate, and repeatable operation.

The outcome of laparoscopic Heller myotomy for achalasia is not influenced by the degree of esophageal dilatation.

PubMed

Sweet, Matthew P; Nipomnick, Ian; Gasper, Warren J; Bagatelos, Karen; Ostroff, James W; Fisichella, Piero M; Way, Lawrence W; Patti, Marco G

2008-01-01

In the past, a Heller myotomy was considered to be ineffective in patients with achalasia and a markedly dilated or sigmoid-shaped esophagus. Esophagectomy was the standard treatment. The aims of this study were (a) to evaluate the results of laparoscopic Heller myotomy and Dor fundoplication in patients with achalasia and various degrees of esophageal dilatation; and (b) to assess the role of endoscopic dilatation in patients with postoperative dysphagia. One hundred and thirteen patients with esophageal achalasia were separated into four groups based on the maximal diameter of the esophageal lumen and the shape of the esophagus: group A, diameter<4.0 cm, 46 patients; group B, esophageal diameter 4.0-6.0 cm, 32 patients; group C, diameter>6.0 cm and straight axis, 23 patients; and group D, diameter>6.0 cm and sigmoid-shaped esophagus, 12 patients. All had a laparoscopic Heller myotomy and Dor fundoplication. The median length of follow-up was 45 months (range 7 months to 12.5 years). The postoperative recovery was similar among the four groups. Twenty-three patients (20%) had postoperative dilatations for dysphagia, and five patients (4%) required a second myotomy. Excellent or good results were obtained in 89% of group A and 91% of groups B, C, and D. None required an esophagectomy to maintain clinically adequate swallowing. These data show that (a) a laparoscopic Heller myotomy relieved dysphagia in most patients with achalasia, even when the esophagus was dilated; (b) about 20% of patients required additional treatment; (c) in the end, swallowing was good in 90%.

Quantitative analysis of iris changes after physiologic and pharmacologic mydriasis in a rural Chinese population.

PubMed

Zhang, Ye; Li, Si Zhen; Li, Lei; He, Ming Guang; Thomas, Ravi; Wang, Ning Li

2014-04-24

To estimate and compare the change in iris cross-sectional area (IA) and iris volume (IV) following physiologic and pharmacologic pupil dilation in primary angle closure suspects (PACS) and normal subjects. Anterior segment-optical coherence tomography (AS-OCT) measurements in light, dark, and following pharmacologic dilation were obtained on 186 PACS and 224 normal subjects examined during the 5-year follow-up of the Handan Eye Study. Iris cross-sectional area, IV, and other biometric parameters calculated using the Zhongshan angle assessment program in the right eyes of all subjects were analyzed. The mean IA and IV decreased in dark compared with light and after pharmacologic dilation in both PACS and normal eyes. This change was statistically significant in normal eyes: light versus pharmacologic dilation for IA (P = 0.038) and for IV, both light versus dark (P = 0.031) and light versus pharmacologic dilation (P = 0.012). A longer axial length (P = 0.028) and a greater change in pupil diameter (PD) (P < 0.001) were associated with a larger decrease of IA for the light to dark comparison. A diagnosis of normal eyes (P = 0.011), larger PD in dark (P = 0.001), and a larger change in PD (P = 0.001) were associated with a larger decrease of IV from light to dark. The differences in iris behavior between PACS and normal rural Chinese subjects following physiologic or pharmacologic pupillary dilation may help provide insights into the pathogenesis of angle closure. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Percutaneous dilatational versus conventional surgical tracheostomy in intensive care patients

PubMed Central

Youssef, Tarek F.; Ahmed, Mohamed Rifaat; Saber, Aly

2011-01-01

Background: Tracheostomy is usually performed in patients with difficult weaning from mechanical ventilation or some catastrophic neurologic insult. Conventional tracheostomy involves dissection of the pretracheal tissues and insertion of the tracheostomy tube into the trachea under direct vision. Percutaneous dilatational tracheostomy is increasingly popular and has gained widespread acceptance in many intensive care unit and trauma centers. Aim: Aim of the study was to compare percutaneous dilatational tracheostomy versus conventional tracheostomy in intensive care patients. Patients and Methods: 64 critically ill patients admitted to intensive care unit subjected to tracheostomy and randomly divided into two groups; percutaneous dilatational tracheostomy and conventional tracheostomy. Results: Mean duration of the procedure was similar between the two procedures while the mean size of tracheostomy tube was smaller in percutaneous technique. In addition, the Lowest SpO2 during procedure, PaCO2 after operation and intra-operative bleeding for both groups were nearly similar without any statistically difference. Postoperative infection after 7 days seen to be statistically lowered and the length of scar tend to be smaller among PDT patients. Conclusion: PDT technique is effective and safe as CST with low incidence of post operative complication. PMID:22361497

30 CFR 1206.262 - Determination of transportation allowances.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 3 2013-07-01 2013-07-01 false Determination of transportation allowances... transportation allowances. (a) Arm's-length contracts. (1) For transportation costs incurred by a lessee pursuant to an arm's-length contract, the transportation allowance shall be the reasonable, actual costs...

30 CFR 1206.262 - Determination of transportation allowances.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Determination of transportation allowances... of transportation allowances. (a) Arm's-length contracts. (1) For transportation costs incurred by a lessee pursuant to an arm's-length contract, the transportation allowance shall be the reasonable, actual...

30 CFR 1206.262 - Determination of transportation allowances.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 3 2014-07-01 2014-07-01 false Determination of transportation allowances... transportation allowances. (a) Arm's-length contracts. (1) For transportation costs incurred by a lessee pursuant to an arm's-length contract, the transportation allowance shall be the reasonable, actual costs...

30 CFR 1206.461 - Determination of transportation allowances.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Determination of transportation allowances... of transportation allowances. (a) Arm's-length contracts. (1) For transportation costs incurred by a lessee pursuant to an arm's-length contract, the transportation allowance shall be the reasonable, actual...

30 CFR 1206.262 - Determination of transportation allowances.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 3 2012-07-01 2012-07-01 false Determination of transportation allowances... transportation allowances. (a) Arm's-length contracts. (1) For transportation costs incurred by a lessee pursuant to an arm's-length contract, the transportation allowance shall be the reasonable, actual costs...

Effects of axisymmetric contractions on turbulence of various scales

NASA Technical Reports Server (NTRS)

Tan-Atichat, J.; Nagib, H. M.; Drubka, R. E.

1980-01-01

Digitally acquired and processed results from an experimental investigation of grid generated turbulence of various scales through and downstream of nine matched cubic contour contractions ranging in area ratio from 2 to 36, and in length to inlet diameter ratio from 0.25 to 1.50 are reported. An additional contraction with a fifth order contour was also utilized for studying the shape effect. Thirteen homogeneous and nearly isotropic test flow conditions with a range of turbulence intensities, length scales and Reynolds numbers were generated and used to examine the sensitivity of the contractions to upstream turbulence. The extent to which the turbulence is altered by the contraction depends on the incoming turbulence scales, the total strain experienced by the fluid, as well as the contraction ratio and the strain rate. Varying the turbulence integral scale influences the transverse turbulence components more than the streamwise component. In general, the larger the turbulence scale, the lesser the reduction in the turbulence intensity of the transverse components. Best agreement with rapid distortion theory was obtained for large scale turbulence, where viscous decay over the contraction length was negligible, or when a first order correction for viscous decay was applied to the results.

Impact of Preoperative Patient Characteristics on Posturethroplasty Recurrence: The Significance of Stricture Length and Prior Treatments

PubMed Central

Bello, Jibril Oyekunle

2016-01-01

Introduction: Urethral strictures are common in urologic practice of Sub-Saharan Africa including Nigeria. We determine the rate of stricture recurrence following urethroplasty for anterior urethral strictures and evaluate preoperative variables that predict of stricture recurrence in our practice. Subjects and Methods: Thirty-six men who had urethroplasty for proven anterior urethral stricture disease between February 2012 and January 2015 were retrospectively analyzed. Preoperative factors including age, socioeconomic factors, comorbidities, etiology of strictures, stricture location, stricture length, periurethral spongiofibrosis, and prior stricture treatments were assessed for independent predictors of stricture recurrence. Results: The median age was 49.5 years (range 21-90), median stricture length was 4 cm (range 1-18 cm) and the overall recurrence rate was 27.8%. Postinfectious strictures, pan urethral strictures or multiple strictures involving the penile and bulbar urethra were more common. Most patients had penile circular fasciocutaneous flap urethroplasty. Following univariate analysis of potential preoperative predictors of stricture recurrence, stricture length, and prior treatments with dilations or urethrotomies were found to be significantly associated with stricture recurrence. On multivariate analysis, they both remained statistically significant. Patients who had prior treatments had greater odds of having a recurrent stricture (odds ratio 18, 95% confidence interval [CI] 1.4–224.3). Stricture length was dichotomized based on receiver operating characteristic (ROC) analysis, and strictures of length ≥5 cm had significantly greater recurrence (area under ROC curve of 0.825, 95% CI 0.690–0.960, P = 0.032). Conclusion: Patients who had prior dilatations or urethrotomies and those with long strictures particularly strictures ≥5 cm have significantly greater odds of developing a recurrence following urethroplasty in Nigerian urology practice. PMID:27843271

The giant protein titin regulates the length of the striated muscle thick filament.

PubMed

Tonino, Paola; Kiss, Balazs; Strom, Josh; Methawasin, Mei; Smith, John E; Kolb, Justin; Labeit, Siegfried; Granzier, Henk

2017-10-19

The contractile machinery of heart and skeletal muscles has as an essential component the thick filament, comprised of the molecular motor myosin. The thick filament is of a precisely controlled length, defining thereby the force level that muscles generate and how this force varies with muscle length. It has been speculated that the mechanism by which thick filament length is controlled involves the giant protein titin, but no conclusive support for this hypothesis exists. Here we show that in a mouse model in which we deleted two of titin's C-zone super-repeats, thick filament length is reduced in cardiac and skeletal muscles. In addition, functional studies reveal reduced force generation and a dilated cardiomyopathy (DCM) phenotype. Thus, regulation of thick filament length depends on titin and is critical for maintaining muscle health.

A case report of achalasia

NASA Astrophysics Data System (ADS)

Sarumpaet, F.; Dairi, L.

2018-03-01

Achalasia is characterized by esophageal nonperistaltic contraction and incomplete relaxation of the lower esophageal sphincter. The most common symptom are dysphagia, regurgitation, and heartburn. A 48 years old male was admitted into HAM General Hospital Medan with achief complaint of dysphagia since adulthood. The patient had to drink a lot of water to help swallow solid or soft food. Complaint worsened in the last three months followed by odynophagia, nausea, and vomiting undigested, retained food. The patient also complained about heartburn and was previously diagnosed with a variant of angina pectoris but his symptoms didn’t improve with medication. The patient had a history of weight loss but no anorexia, no prior history of corrosive ingestion. The patient was an active smoker. Physical examination revealed no abnormality. Oesophagogram showed dilated distal esophagus with rat tail appearance. Gastroscopy revealed dilatation on the lower third of the esophagus. Computed Tomography revealed dilatation of distal esophagus. Based on the results of the exams, we concluded the diagnosis as achalasia. The patient was treated with calcium channel blocker and proton pump inhibitor. The patient showed clinical improvement after treated and was discharged. The patient was planned for once a month follow up in the outpatient clinic.

Characterization of adrenergic receptors of the cat iris and nictitating membrane.

PubMed

Koss, M C; Hey, J A; Gherezghiher, T

1990-01-01

Graded pupillary dilations and nictitating membrane (NM) contractions were elicited in anesthetized cats by electrical stimulation of the preganglionic sympathetic nerve or by i.a. administration of norepinephrine (NE) or phenylephrine into the carotid artery. Pupil and NM responses were measured simultaneously from the same side. Alpha-adrenoceptor antagonists were administered intravenously. All of the alpha 1-adrenoceptor blockers tested produced a dose-related reduction of NM responses to both neural and agonist activation; the potency rank order was prazosin greater than WB-4101 greater than phentolamine greater than phenoxybenzamine (PBZ). In contrast, responses of the iris dilator were antagonized only by WB-4101 and PBZ. The iris was almost totally refractory to doses of prazosin and phentolamine that blocked NM responses by more than 75% of control. Neither alpha 2- nor beta-adrenoceptor antagonism produced significant inhibition of neural or agonist activation of either organ (with the exception of high doses of yohimbine on the NM). These results suggest that the postjunctional adrenoceptors of the NM are exclusively of the alpha 1-adrenoceptor subtype. In contrast, those of the iris dilator muscle cannot be easily classified pharmacologically as either alpha 1 or alpha 2-adrenoceptors.

48 CFR 12.207 - Contract type.

Code of Federal Regulations, 2011 CFR

2011-10-01

... contracts or fixed-price contracts with economic price adjustment for the acquisition of commercial items... fixed-price with economic price adjustment contracts (e.g., by limiting the value or length of the time... maximize the use of firm-fixed-price or fixed-price with economic price adjustment contracts on future...

30 CFR 206.102 - How do I calculate royalty value for oil that I or my affiliate sell(s) under an arm's-length...

Code of Federal Regulations, 2010 CFR

2010-07-01

... or my affiliate sell(s) under an arm's-length contract? 206.102 Section 206.102 Mineral Resources... Federal Oil § 206.102 How do I calculate royalty value for oil that I or my affiliate sell(s) under an arm... seller under the arm's-length contract, less applicable allowances determined under §§ 206.110 or 206.111...

A Proposal for Qualification Standards as a Contracting Officer in the Naval Facilities Engineering Command.

DTIC Science & Technology

1985-06-01

4. Government Contract Law , DMET PPM 302 (JT); two weeks in length...ccitent: reviews basic legal principles and sources of contract law , modifications, termina- tions, remedies, interpretation of contract language...Governmepnt Contract Law PPM 302 (JT) ____ _____ Recomripnded Optional Courses 1. Advanced Contract Administration PPM 304 (IT) _ ___ _____ 2. Management of

Isolated effect of geometry on mitral valve function for in silico model development.

PubMed

Siefert, Andrew William; Rabbah, Jean-Pierre Michel; Saikrishnan, Neelakantan; Kunzelman, Karyn Susanne; Yoganathan, Ajit Prithivaraj

2015-01-01

Computational models for the heart's mitral valve (MV) exhibit several uncertainties that may be reduced by further developing these models using ground-truth data-sets. This study generated a ground-truth data-set by quantifying the effects of isolated mitral annular flattening, symmetric annular dilatation, symmetric papillary muscle (PM) displacement and asymmetric PM displacement on leaflet coaptation, mitral regurgitation (MR) and anterior leaflet strain. MVs were mounted in an in vitro left heart simulator and tested under pulsatile haemodynamics. Mitral leaflet coaptation length, coaptation depth, tenting area, MR volume, MR jet direction and anterior leaflet strain in the radial and circumferential directions were successfully quantified at increasing levels of geometric distortion. From these data, increase in the levels of isolated PM displacement resulted in the greatest mean change in coaptation depth (70% increase), tenting area (150% increase) and radial leaflet strain (37% increase) while annular dilatation resulted in the largest mean change in coaptation length (50% decrease) and regurgitation volume (134% increase). Regurgitant jets were centrally located for symmetric annular dilatation and symmetric PM displacement. Asymmetric PM displacement resulted in asymmetrically directed jets. Peak changes in anterior leaflet strain in the circumferential direction were smaller and exhibited non-significant differences across the tested conditions. When used together, this ground-truth data-set may be used to parametrically evaluate and develop modelling assumptions for both the MV leaflets and subvalvular apparatus. This novel data may improve MV computational models and provide a platform for the development of future surgical planning tools.

Quantification of annular dilatation and papillary muscle separation in functional mitral regurgitation: role of anterior mitral leaflet length as reference.

PubMed

Jorapur, Vinod; Voudouris, Apostolos; Lucariello, Richard J

2005-07-01

We hypothesized that anterior mitral leaflet length (ALL) does not differ significantly between normal subjects and patients with functional mitral regurgitation (FMR) and hence may be used as a reference measurement to quantify annular dilatation and papillary muscle separation. We prospectively studied 50 controls, 15 patients with systolic left ventricular dysfunction (LVD) with significant FMR, and 15 patients with LVD without significant FMR. Significant MR was defined as an effective regurgitant orifice area > or = 0.2 cm2 as measured by the flow convergence method. Annular diameter, interpapillary distance, and ALL were measured, and the following ratios were derived: annular diameter indexed to ALL (ADI) and interpapillary distance indexed to ALL (IPDI). There was no significant difference in ALL among the three groups. The mean ADI was 1.26 times controls in patients with LVD without significant FMR compared to 1.33 times controls in patients with LVD with significant FMR (P = 0.06, no significant difference between groups). The mean IPDI was 1.42 times controls in patients with LVD without significant FMR compared to 2.1 times controls in patients with LVD with significant FMR (P < 0.0001, significant difference between groups). There was no significant difference in ALL between controls and patients with LVD. ALL can be used as a reference measurement to quantify annular dilatation and papillary muscle separation in patients with FMR. Interpapillary distance but not annular diameter indexed to ALL correlates with severity of FMR.

Pancreaticobiliary maljunction and biliary cancer.

PubMed

Kamisawa, Terumi; Kuruma, Sawako; Tabata, Taku; Chiba, Kazuro; Iwasaki, Susumu; Koizumi, Satomi; Kurata, Masanao; Honda, Goro; Itoi, Takao

2015-03-01

Pancreaticobiliary maljunction (PBM) is a congenital malformation in which the pancreatic and bile ducts join anatomically outside the duodenal wall. Japanese clinical practice guidelines on how to deal with PBM were made in 2012, representing a world first. According to the 2013 revision to the diagnostic criteria for PBM, in addition to direct cholangiography, diagnosis can be made by magnetic resonance cholangiopancreatography (MRCP), 3-dimensional drip infusion cholangiography computed tomography, endoscopic ultrasonography (US), or multiplanar reconstruction images by multidetector row computed tomography. In PBM, the common channel is so long that sphincter action does not affect the pancreaticobiliary junction, and pancreatic juice frequently refluxes into the biliary tract. Persistence of refluxed pancreatic juice injures epithelium of the biliary tract and promotes cancer development, resulting in higher rates of carcinogenesis in the biliary tract. In a nationwide survey, biliary cancer was detected in 21.6% of adult patients with congenital biliary dilatation (bile duct cancer, 32.1% vs. gallbladder cancer, 62.3%) and in 42.4% of PBM patients without biliary dilatation (bile duct cancer, 7.3% vs. gallbladder cancer, 88.1%). Pathophysiological conditions due to pancreatobiliary reflux occur in patients with high confluence of pancreaticobiliary ducts, a common channel ≥6 mm long, and occlusion of communication during contraction of the sphincter. Once the diagnosis of PBM is established, immediate prophylactic surgery is recommended. However, the surgical strategy for PBM without biliary dilatation remains controversial. To detect PBM without biliary dilatation early, MRCP is recommended for patients showing gallbladder wall thickening on screening US under suspicion of PBM.

Activated Braf induces esophageal dilation and gastric epithelial hyperplasia in mice.

PubMed

Inoue, Shin-Ichi; Takahara, Shingo; Yoshikawa, Takeo; Niihori, Tetsuya; Yanai, Kazuhiko; Matsubara, Yoichi; Aoki, Yoko

2017-12-01

Germline mutations in BRAF are a major cause of cardio-facio-cutaneous (CFC) syndrome, which is characterized by heart defects, characteristic craniofacial dysmorphology and dermatologic abnormalities. Patients with CFC syndrome also commonly show gastrointestinal dysfunction, including feeding and swallowing difficulties and gastroesophageal reflux. We have previously found that knock-in mice expressing a Braf Q241R mutation exhibit CFC syndrome-related phenotypes, such as growth retardation, craniofacial dysmorphisms, congenital heart defects and learning deficits. However, it remains unclear whether BrafQ241R/+ mice exhibit gastrointestinal dysfunction. Here, we report that BrafQ241R/+ mice have neonatal feeding difficulties and esophageal dilation. The esophagus tissues from BrafQ241R/+ mice displayed incomplete replacement of smooth muscle with skeletal muscle and decreased contraction. Furthermore, the BrafQ241R/+ mice showed hyperkeratosis and a thickened muscle layer in the forestomach. Treatment with MEK inhibitors ameliorated the growth retardation, esophageal dilation, hyperkeratosis and thickened muscle layer in the forestomach in BrafQ241R/+ mice. The esophageal dilation with aberrant skeletal-smooth muscle boundary in BrafQ241R/+ mice were recovered after treatment with the histone H3K27 demethylase inhibitor GSK-J4. Our results provide clues to elucidate the pathogenesis and possible treatment of gastrointestinal dysfunction and failure to thrive in patients with CFC syndrome. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Alterations in atrial electrophysiology and tissue structure in a canine model of chronic atrial dilatation due to mitral regurgitation.

PubMed

Verheule, Sander; Wilson, Emily; Everett, Thomas; Shanbhag, Sujata; Golden, Catherine; Olgin, Jeffrey

2003-05-27

Clinically, chronic atrial dilatation is associated with an increased incidence of atrial fibrillation (AF), but the underlying mechanism is not clear. We have investigated atrial electrophysiology and tissue structure in a canine model of chronic atrial dilatation due to mitral regurgitation (MR). Thirteen control and 19 MR dogs (1 month after partial mitral valve avulsion) were studied. Dogs in the MR group were monitored using echocardiography and Holter recording. In open-chest follow-up experiments, electrode arrays were placed on the atria to investigate conduction patterns, effective refractory periods, and inducibility of AF. Alterations in tissue structure and ultrastructure were assessed in atrial tissue samples. At follow-up, left atrial length in MR dogs was 4.09+/-0.45 cm, compared with 3.25+/-0.28 at baseline (P<0.01), corresponding to a volume of 205+/-61% of baseline. At follow-up, no differences in atrial conduction pattern and conduction velocities were noted between control and MR dogs. Effective refractory periods were increased homogeneously throughout the left and right atrium. Sustained AF (>1 hour) was inducible in 10 of 19 MR dogs and none of 13 control dogs (P<0.01). In the dilated MR left atrium, areas of increased interstitial fibrosis and chronic inflammation were accompanied by increased glycogen ultrastructurally. Chronic atrial dilatation in the absence of overt heart failure leads to an increased vulnerability to AF that is not based on a decrease in wavelength.

75 FR 70279 - Agency Information Collection Activities: Submitted for Office of Management and Budget Review...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-11-17

...-length AUDIT PROCESS transmission contracts, See Note. production and operating agreements and related... production method. 1206.458(c)(1)(iv) and (c)(2)(vi).. Submit arm's-length washing AUDIT PROCESS contracts...). The Secretary is required by various laws to manage mineral resource production from Federal and...

Co-seismic Static Stress Drops for Earthquake Ruptures Nucleated on Faults After Progressive Strain Localization

NASA Astrophysics Data System (ADS)

Griffith, W. A.; Nielsen, S.; di Toro, G.; Pollard, D. D.; Pennacchioni, G.

2007-12-01

We estimate the coseismic static stress drop on small exhumed strike-slip faults in the Mt. Abbot quadrangle of the central Sierra Nevada (California). The sub-vertical strike-slip faults cut ~85 Ma granodiorite, were exhumed from 7-10 km depth, and were chosen because they are exposed along their entire lengths, ranging from 8 to 13 m. Net slip is estimated using offset aplite dikes and shallowly plunging slickenlines on the fault surfaces. The faults show a record of progressive strain localization: slip initially nucleated on joints and accumulated from ductile shearing (quartz-bearing mylonites) to brittle slipping (epidote-bearing cataclasites). Thin (< 1 mm) pseudotachylytes associated with the cataclasites have been identified along some faults, suggesting that brittle slip may have been seismic. The brittle contribution to slip may be distinguished from the ductile shearing because epidote-filled, rhombohedral dilational jogs opened at bends and step-overs during brittle slip, are distributed periodically along the length of the faults. We argue that brittle slip occurred along the measured fault lengths in single slip events based on several pieces of evidence. 1) Epidote crystals are randomly oriented and undeformed within dilational jogs, indicating they did not grow during aseismic slip and were not broken after initial opening and precipitation. 2) Opening-mode splay cracks are concentrated near fault tips rather than the fault center, suggesting that the reactivated faults ruptured all at once rather than in smaller slip patches. 3) The fact that the opening lengths of the dilational jogs vary systematically along the fault traces suggests that brittle reactivation occurred in a single slip event along the entire fault rather than in multiple slip events. This unique combination of factors distinguishes this study from previous attempts to estimate stress drop from exhumed faults because we can constrain the coseismic rupture length and slip. The static stress drop is calculated for a circular fault using the length of the mapped faults and their slip distributions as well as the shear modulus of the host granodiorite measured in the laboratory. Calculations yield stress drops on the order of 100-200 MPa, one to two orders of magnitude larger than typical seismological estimates. The studied seismic ruptures occurred along small, deep-seated faults (10 km depth), and, given the fault mineral filling (quartz-bearing mylonites) these were "strong" faults. Our estimates are consistent with static stress drops estimated by Nadeau and Johnson (1998) for small repeated earthquakes.

Multi-Physics MRI-Based Two-Layer Fluid-Structure Interaction Anisotropic Models of Human Right and Left Ventricles with Different Patch Materials: Cardiac Function Assessment and Mechanical Stress Analysis

PubMed Central

Tang, Dalin; Yang, Chun; Geva, Tal; Gaudette, Glenn; del Nido, Pedro J.

2011-01-01

Multi-physics right and left ventricle (RV/LV) fluid-structure interaction (FSI) models were introduced to perform mechanical stress analysis and evaluate the effect of patch materials on RV function. The FSI models included three different patch materials (Dacron scaffold, treated pericardium, and contracting myocardium), two-layer construction, fiber orientation, and active anisotropic material properties. The models were constructed based on cardiac magnetic resonance (CMR) images acquired from a patient with severe RV dilatation and solved by ADINA. Our results indicate that the patch model with contracting myocardium leads to decreased stress level in the patch area, improved RV function and patch area contractility. PMID:21765559

Randomized trial of oral misoprostol treatment for cervical ripening before tandem application in cervix cancer.

PubMed

Cepni, Kimia; Gul, Sule; Cepni, Ismail; Güralp, Onur; Sal, Veysel; Mayadagli, Alpaslan

2011-11-01

To investigate the efficacy of oral misoprostol administered to facilitate tandem application to the cervix as a part of brachytherapy in patients with cervical cancer. Eighty patients with cervical cancer who had been planned to undergo brachytherapy at Dr. Lütfi Kırdar Kartal Training and Research Hospital were evaluated in a double-blind, prospective, randomized trial. Patients were divided randomly into two groups of 40 patients. The first and second groups received 400 μg of misoprostol orally and placebo, respectively, 3 h before tandem application. The two groups were compared in terms of age, diameter of tumor, parity, age at first intercourse, amount of bleeding and pain at first tandem application, length of endometrial cavity measured by hysterometer, and size of Hegar dilators used for cervical dilatation. Of all cases, 63.6%, 16.3%, 10%, 6.3%, 2.5%, and 1.3% were Stage IIB, IIIB, IIIA, IVA, IIA and IIC, respectively. Mean (±SD) age (range) was 49.3 ± 13.1 (25-83) years and 56.6 ± 13.2 (30-78) years in the study and control groups, respectively (p = 0.015). Age at first intercourse, diameter of tumor, parity, amount of bleeding at first tandem application, and length of endometrial cavity measured by hysterometer were not significantly different between the two groups. Pain score was significantly higher in the control group (p < 0.001). Application was significantly easier in the study group compared with controls (p < 0.001). Average size of initial Hegar dilators used for cervical dilatation was significantly higher in the study group compared with controls (p = 0.017). Administration of misoprostol 400 μg orally for cervical ripening before tandem application facilitates the procedure, increases patient tolerability and comfort, and may decrease complication rates. Copyright © 2011 Elsevier Inc. All rights reserved.

Delayed versus immediate pushing in second stage of labor.

PubMed

Kelly, Mary; Johnson, Eileen; Lee, Vickie; Massey, Liz; Purser, Debbie; Ring, Karen; Sanderson, Stephanye; Styles, Juanita; Wood, Deb

2010-01-01

Comparison of two different methods for management of second stage of labor: immediate pushing at complete cervical dilation of 10 cm and delayed pushing 90 minutes after complete cervical dilation. This study was a randomized clinical trial in a labor and delivery unit of a not-for-profit community hospital. A sample of 44 nulliparous mothers with continuous epidural anesthesia were studied after random assignment to treatment groups. Subjects were managed with either immediate or delayed pushing during the second stage of labor at the time cervical dilation was complete. The primary outcome measure was the length of pushing during second stage of labor. Secondary outcomes included length of second stage of labor, maternal fatigue and perineal injuries, and fetal heart rate decelerations. Two-tailed, unpaired Student's t-tests and Chi-square analysis were used for data analysis. Level of significance was set at p < .01 following a Bonferroni correction for multiple t-tests. A total of 44 subjects received the study intervention (N = 28 immediate pushing; N = 16 delayed pushing). The delayed pushing group had significantly shorter amount of time spent in pushing compared with the immediate pushing group (38.9 +/- 6.9 vs. 78.7 +/- 7.9 minutes, respectively, p = .002). Maternal fatigue scores, perineal injuries, and fetal heart rate decelerations were similar for both groups. Delaying pushing for up to 90 minutes after complete cervical dilation resulted in a significant decrease in the time mothers spent pushing without a significant increase in total time in second stage of labor.In clinical practice, healthcare providers sometimes resist delaying the onset of pushing after second stage of labor has begun because of a belief it will increase labor time. This study's finding of a 51% reduction in pushing time when mothers delay pushing for up to 90 minutes, with no significant increase in overall time for second stage of labor, disputes that concern.

Chemical laser exhaust pipe design research

NASA Astrophysics Data System (ADS)

Sun, Yunqiang; Huang, Zhilong; Chen, Zhiqiang; Ren, Zebin; Guo, Longde

2016-10-01

In order to weaken the chemical laser exhaust gas influence of the optical transmission, a vent pipe is advised to emissions gas to the outside of the optical transmission area. Based on a variety of exhaust pipe design, a flow field characteristic of the pipe is carried out by numerical simulation and analysis in detail. The research results show that for uniform deflating exhaust pipe, although the pipeline structure is cyclical and convenient for engineering implementation, but there is a phenomenon of air reflows at the pipeline entrance slit which can be deduced from the numerical simulation results. So, this type of pipeline structure does not guarantee seal. For the design scheme of putting the pipeline contract part at the end of the exhaust pipe, or using the method of local area or tail contraction, numerical simulation results show that backflow phenomenon still exists at the pipeline entrance slit. Preliminary analysis indicates that the contraction of pipe would result in higher static pressure near the wall for the low speed flow field, so as to produce counter pressure gradient at the entrance slit. In order to eliminate backflow phenomenon at the pipe entrance slit, concerned with the pipeline type of radial size increase gradually along the flow, flow field property in the pipe is analyzed in detail by numerical simulation methods. Numerical simulation results indicate that there is not reflow phenomenon at entrance slit of the dilated duct. However the cold air inhaled in the slit which makes the temperature of the channel wall is lower than the center temperature. Therefore, this kind of pipeline structure can not only prevent the leak of the gas, but also reduce the wall temperature. In addition, compared with the straight pipe connection way, dilated pipe structure also has periodic structure, which can facilitate system integration installation.

Electrophysiological effects of acute atrial stretch on persistent atrial fibrillation in patients undergoing open heart surgery.

PubMed

Elvan, Arif; Adiyaman, Ahmet; Beukema, Rypko J; Sie, Hauw T; Allessie, Maurits A

2013-03-01

The electrophysiologic effects of acute atrial dilatation and dedilatation in humans with chronic atrial fibrillation remains to be elucidated. To study the electrophysiological effects of acute atrial dedilatation and subsequent dilatation in patients with long-standing persistent atrial fibrillation (AF) with structural heart disease undergoing elective cardiac surgery. Nine patients were studied. Mean age was 71 ± 10 years, and left ventricular ejection was 46% ± 6%. Patients had at least moderate mitral valve regurgitation and dilated atria. After sternotomy and during extracorporal circulation, mapping was performed on the beating heart with 2 multielectrode arrays (60 electrodes each, interelectrode distance 1.5 mm) positioned on the lateral wall of the right atrium (RA) and left atrium (LA). Atrial pressure and size were altered by modifying extracorporal circulation. AF electrograms were recorded at baseline after dedilation and after dilatation of the atria afterward. At baseline, the median AF cycle length (mAFCL) was 184 ± 27 ms in the RA and 180 ± 17 ms in the LA. After dedilatation, the mAFCL shortened significantly to 168 ± 13 ms in the RA and to 168 ± 20 ms in the LA. Dilatation lengthened mAFCL significantly to 189 ± 17 ms in the RA and to 185 ± 23 ms in the LA. Conduction block (CB) at baseline was 14.3% ± 3.6% in the RA and 17.3% ± 5.5% in the LA. CB decreased significantly with dedilatation to 7.4% ± 2.9% in the RA and to 7.9% ± 6.3% in the LA. CB increased significantly with dilatation afterward to 15.0% ± 8.3% in the RA and to 18.5% ± 16.0% in the LA. Acute dedilatation of the atria in patients with long-standing persistent AF causes a decrease in the mAFCL in both atria. Subsequent dilatation increased the mAFCL. The amount of CB decreased with dedilatation and increased with dilatation afterward in both atria. Copyright © 2013 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Regulation of increased blood flow (hyperemia) to muscles during exercise: a hierarchy of competing physiological needs.

PubMed

Joyner, Michael J; Casey, Darren P

2015-04-01

This review focuses on how blood flow to contracting skeletal muscles is regulated during exercise in humans. The idea is that blood flow to the contracting muscles links oxygen in the atmosphere with the contracting muscles where it is consumed. In this context, we take a top down approach and review the basics of oxygen consumption at rest and during exercise in humans, how these values change with training, and the systemic hemodynamic adaptations that support them. We highlight the very high muscle blood flow responses to exercise discovered in the 1980s. We also discuss the vasodilating factors in the contracting muscles responsible for these very high flows. Finally, the competition between demand for blood flow by contracting muscles and maximum systemic cardiac output is discussed as a potential challenge to blood pressure regulation during heavy large muscle mass or whole body exercise in humans. At this time, no one dominant dilator mechanism accounts for exercise hyperemia. Additionally, complex interactions between the sympathetic nervous system and the microcirculation facilitate high levels of systemic oxygen extraction and permit just enough sympathetic control of blood flow to contracting muscles to regulate blood pressure during large muscle mass exercise in humans. Copyright © 2015 the American Physiological Society.

Regulation of Increased Blood Flow (Hyperemia) to Muscles During Exercise: A Hierarchy of Competing Physiological Needs

PubMed Central

Joyner, Michael J.; Casey, Darren P.

2015-01-01

This review focuses on how blood flow to contracting skeletal muscles is regulated during exercise in humans. The idea is that blood flow to the contracting muscles links oxygen in the atmosphere with the contracting muscles where it is consumed. In this context, we take a top down approach and review the basics of oxygen consumption at rest and during exercise in humans, how these values change with training, and the systemic hemodynamic adaptations that support them. We highlight the very high muscle blood flow responses to exercise discovered in the 1980s. We also discuss the vasodilating factors in the contracting muscles responsible for these very high flows. Finally, the competition between demand for blood flow by contracting muscles and maximum systemic cardiac output is discussed as a potential challenge to blood pressure regulation during heavy large muscle mass or whole body exercise in humans. At this time, no one dominant dilator mechanism accounts for exercise hyperemia. Additionally, complex interactions between the sympathetic nervous system and the microcirculation facilitate high levels of systemic oxygen extraction and permit just enough sympathetic control of blood flow to contracting muscles to regulate blood pressure during large muscle mass exercise in humans. PMID:25834232

Caffeine and length dependence of staircase potentiation in skeletal muscle.

PubMed

Rassier, D E; Tubman, L A; MacIntosh, B R

1998-01-01

Skeletal muscle sensitivity to Ca2+ is greater at long lengths, and this results in an optimal length for twitch contractions that is longer than optimal length for tetanic contractions. Caffeine abolishes this length dependence of Ca2+ sensitivity. Muscle length (ML) also affects the degree of staircase potentiation. Since staircase potentiation is apparently caused by an increased Ca2+ sensitivity of the myofilaments, we tested the hypothesis that caffeine depresses the length dependence of staircase potentiation. In situ isometric twitch contractions of rat gastrocnemius muscle before and after 10 s of 10-Hz stimulation were analyzed at seven different lengths to evaluate the length dependence of staircase potentiation. In the absence of caffeine, length dependence of Ca2+ sensitivity was observed, and the degree of potentiation after 10-Hz stimulation showed a linear decrease with increased length (DT = 1.47 - 0.05 ML, r2 = 0.95, where DT is developed tension). Length dependence of Ca2+ sensitivity was decreased by caffeine when caffeine was administered in amounts estimated to result in 0.5 and 0.75 mM concentrations. Furthermore, the negative slope of the relationship between staircase potentiation and muscle length was diminished at the lower caffeine dose, and the slope was not different from zero after the higher dose (DT = 1.53 - 0.009 ML, r2 = 0.43). Our study shows that length dependence of Ca2+ sensitivity in intact skeletal muscle is diminished by caffeine. Caffeine also suppressed the length dependence of staircase potentiation, suggesting that the mechanism of this length dependence may be closely related to the mechanism for length dependence of Ca2+ sensitivity.

Summary Report: Visitor Safety and Security at Corps of Engineers Projects.

DTIC Science & Technology

1982-10-01

23 Incident Reporting System. ..... .............. 23 Contract Law Enforcement ...... .............. 25 Project Management...average length of stay being 3.3 days. Contract Law Enforcement Conclusions , The Corps’ contract law enforcement program is extremely fragile in terms...to prohibit the public display alcoholic beverages and consumption of alcoholic beverages. Use contract law initiate law enforcement contracts

Predictors of urethral stricture recurrence after endoscopic urethrotomy.

PubMed

Redón-Gálvez, L; Molina-Escudero, R; Álvarez-Ardura, M; Otaola-Arca, H; Alarcón Parra, R O; Páez-Borda, Á

2016-10-01

The aim of the study was to analyse the clinical-demographic variables of the series and the predictors of urethral stricture recurrence after endoscopic urethrotomy. We retrospectively analysed 67 patients who underwent Sachse endoscopic urethrotomy between June 2006 and September 2014. Those patients who had previously undergone endoscopic urethrotomy or urethroplasty were excluded. The other patients who presented urethral stricture were included. We analysed age, weight, smoking habit, and cardiovascular risk factors, as well as the number, location, length and aetiology of the strictures, previous urethrotomies, vesical catheter duration and postsurgical dilatations. A univariate and multivariate analysis was conducted using the chi-squared test or Fisher's test and logistic regression to identify the variables related to recurrence. Thirty-seven percent of the patients had a relapse. The majority of the patients were older than 60 years (56.7%), obese (74.6%), nonsmokers (88%) and had no cardiovascular factors (56.7%). The majority of the strictures were single (94%), <1cm (82%), bulbar urethral (64.2%), iatrogenic (67.2%) and with no prior urethrotomy (89.6%). The majority of the patients carried a vesical catheter for <15 days (85.1%) and did not undergo postsurgical dilatation (65.7%). Only the length of the stricture was an independent risk factor for recurrence (P=.025; relative risk, 5.7; 95% CI 1.21-26.41). In the treatment of urethral strictures through endoscopic urethrotomy, a stricture length >1cm is the only factor that predicts an increase in the risk of recurrence. We found no clinical or demographic factors that caused an increase in the incidence of recurrence. Similarly, technical factors such as increasing the bladder catheterisation time and urethral dilatations did not change the course of the disease. Their routine use is therefore unnecessary. Copyright © 2016 AEU. Publicado por Elsevier España, S.L.U. All rights reserved.

High-Resolution Manometry Evaluation of the Pharynx and Upper Esophageal Sphincter Motility in Patients with Achalasia.

PubMed

Menezes, Mariano A; Herbella, Fernando A M; Patti, Marco G

2015-10-01

The motility of the pharynx and upper esophageal sphincter (UES) is still poorly understood. It is also unclear if the motility of this area may be compromised in patients with achalasia. This study aims to evaluate the motility of the pharynx, UES, and proximal esophagus in patients with esophageal achalasia. Sixty patients with achalasia underwent high-resolution manometry (HRM) (52 % females, mean age 54 years). Esophageal dilatation was classified according to the radiologic diameter in Type I (<4 cm): 6 %; Type II (4-7 cm): 36 %; Type III (7-10 cm): 34 %; and Type IV (>10 cm): 24 %. HRM classified 43 % of the patients as Chicago Type I and 57 % as Type II. Manometric parameters were compared to normal values obtained from a previous study in volunteers. The motility of the velopharynx showed short, premature, and hypertonic contraction. The epiglottis also showed hypertonic contraction. The UES had increased residual pressure. Chicago classification Type II patients had higher UES residual pressure (p = 0.03). The degree of esophageal dilatation did not correlate with manometric parameters. Achalasia may affect the motility of the pharyngo-upper esophageal area. The changes observed may represent functional alterations to prevent aspiration, especially in patients with Chicago classification Type II achalasia.

Movement of Landslide Triggered by Bedrock Exfiltration with Nonuniform Pore Pressure Distribution

NASA Astrophysics Data System (ADS)

Jan, C. D.; Jian, Z. K.

2014-12-01

Landslides are common phenomena of sediment movement in mountain areas and usually pose severe risks to people and infrastructure around those areas. The occurrence of landslides is influenced by groundwater dynamics and bedrock characteristics as well as by rainfall and soil-mass properties. The bedrock may drain or contribute to groundwater in the overlying soil mass, depending on the hydraulic conductivity, degree of fracturing, saturation, and hydraulic head. Our study here is based on the model proposed by Iverson (2005). The model describes the relation between landslide displacement and the shear-zone dilation/contraction of pore water pressure. To study landslide initiation and movement, a block soil mass sliding down an inclined beck-rock plane is governed by Newton's equation of motion, while both the bedrock exfiltration and excess pore pressure induced by dilatation or contraction of basal shear zone are described by diffusion equations. The Chebyshev collocation method was used to transform the governing equations to a system of first-order ordinary differential equations, without the need of iteration. Then a fourth-order Runge-Kutta scheme was used to solve these ordinary differential equations. The effects of nonuniform bedrock exfiltration pressure distributions, such as the delayed peak, central peak, and advanced peak distributions, on the time of landslide initiation and the speed of landslide movement were compared and discussed.

Dynamic Features for Iris Recognition.

PubMed

da Costa, R M; Gonzaga, A

2012-08-01

The human eye is sensitive to visible light. Increasing illumination on the eye causes the pupil of the eye to contract, while decreasing illumination causes the pupil to dilate. Visible light causes specular reflections inside the iris ring. On the other hand, the human retina is less sensitive to near infra-red (NIR) radiation in the wavelength range from 800 nm to 1400 nm, but iris detail can still be imaged with NIR illumination. In order to measure the dynamic movement of the human pupil and iris while keeping the light-induced reflexes from affecting the quality of the digitalized image, this paper describes a device based on the consensual reflex. This biological phenomenon contracts and dilates the two pupils synchronously when illuminating one of the eyes by visible light. In this paper, we propose to capture images of the pupil of one eye using NIR illumination while illuminating the other eye using a visible-light pulse. This new approach extracts iris features called "dynamic features (DFs)." This innovative methodology proposes the extraction of information about the way the human eye reacts to light, and to use such information for biometric recognition purposes. The results demonstrate that these features are discriminating features, and, even using the Euclidean distance measure, an average accuracy of recognition of 99.1% was obtained. The proposed methodology has the potential to be "fraud-proof," because these DFs can only be extracted from living irises.

Granular mechanics of normally consolidated fine soils

NASA Astrophysics Data System (ADS)

Yanqui, Calixtro

2017-06-01

In this paper, duality is demonstrated to be one of the inherent properties of granular packings, by mapping the stress-strain curve into the diagram that relates the pore ratio and the localization of the contact point. In this way, it is demonstrated that critical state is not related to the maximum void ratio, but to a unique value related to two different angles of packing, one limiting the domain of the dense state, and other limiting the domain of the loose state. As a consequence, packings can be dilative or contractive, as mutually exclusive states, except by the critical state point, where equations for both granular packings are equally valid. Further analysis shows that stresses, in a dilative packing, are transmitted by chains of contact forces, and, in a contractive packing, by shear forces. So that, stresses, for the first case, depend on the initial void ratio, and, for the second case, are independent. As it is known, normally consolidated and lightly overconsolidated fine soils are in loose state, and, hence, their strength is constant, because it does not depend on their initial void ratio; except at the critical state, for which, the consolidated-drained angle of friction is related to the plasticity index or the liquid limit. In this fashion, experimental results reported by several authors around the world are confronted with the theory, showing a good agreement.

Effects of aromatherapy with Rosa damascena on nulliparous women's pain and anxiety of labor during first stage of labor.

PubMed

Hamdamian, Sepideh; Nazarpour, Soheila; Simbar, Masoumeh; Hajian, Sepideh; Mojab, Faraz; Talebi, Atefeh

2018-03-01

Reducing labor pain and anxiety is one of the most important goals of maternity care. This study aimed to assess the effects of aromatherapy with Rosa damascena on pain and anxiety in the first stage of labor among nulliparous women. This was a randomized clinical trial of 110 nulliparous women. The eligible participants were randomly assigned to two groups of aromatherapy and control in an Iranian maternity hospital. The participants received 0.08 mL of Rosa damascena essence in the aromatherapy group and 0.08 mL of normal saline in the control group, every 30 min. Pain was measured 3 times, once each at three stages of cervical dilation (4-5, 6-7, and 8-10 cm). Anxiety was measured twice, once each at two stages of cervical dilation (4-7 and 8-10 cm). The tools for data collection were the Spielberger anxiety questionnaire, numerical pain rating scale, demographic and obstetric questionnaire, and an observational checklist. Data analyses included the t-test, Mann-Whitney U test and Chi-square test. Severity of labor pain and severity of anxiety were used as primary outcome measures. Labor and delivery characteristics (including number of contractions, duration of contractions in second stage, Bishop score, augmentation by oxytocin, Apgar score, and mode of delivery), demographic characteristics, and fertility information were used as secondary outcome measures. Pain severity in the group receiving aromatherapy with R. damascena was significantly lower than in the control group after treatment at each pain assessment (cervical dilation of 4-5, 6-7, and 8-10 cm; P < 0.05). Anxiety levels were also significantly lower in the treatment group than in the control group after treatment at each time of measurement (cervical dilation of 4-7 and 8-10 cm; P < 0.05). Aromatherapy with R. damascena reduced the severity of pain and anxiety in the first stage of labor. Aromatherapy with R. damascena is a convenient and effective method for pain and anxiety reduction during the first stage of labor. Iranian Registry of Clinical Trial: IRCT201306258801N3. Copyright © 2018 Shanghai Changhai Hospital. Published by Elsevier B.V. All rights reserved.

Abnormalities in intracellular calcium regulation and contractile function in myocardium from dogs with pacing-induced heart failure

NASA Technical Reports Server (NTRS)

Perreault, C. L.; Shannon, R. P.; Komamura, K.; Vatner, S. F.; Morgan, J. P.

1992-01-01

24 d of rapid ventricular pacing induced dilated cardiomyopathy with both systolic and diastolic dysfunction in conscious, chronically instrumented dogs. We studied mechanical properties and intracellular calcium (Ca2+i) transients of trabeculae carneae isolated from 15 control dogs (n = 32) and 11 dogs with pacing-induced cardiac failure (n = 26). Muscles were stretched to maximum length at 30 degrees C and stimulated at 0.33 Hz; a subset (n = 17 control, n = 17 myopathic) was loaded with the [Ca2+]i indicator aequorin. Peak tension was depressed in the myopathic muscles, even in the presence of maximally effective (i.e., 16 mM) [Ca2+] in the perfusate. However, peak [Ca2+]i was similar (0.80 +/- 0.13 vs. 0.71 +/- 0.05 microM; [Ca2+]o = 2.5 mM), suggesting that a decrease in Cai2+ availability was not responsible for the decreased contractility. The time for decline from the peak of the Cai2+ transient was prolonged in the myopathic group, which correlated with prolongation of isometric contraction and relaxation. However, similar end-diastolic [Ca2+]i was achieved in both groups (0.29 +/- 0.05 vs. 0.31 +/- 0.02 microM), indicating that Cai2+ homeostasis can be maintained in myopathic hearts. The inotropic response of the myopathic muscles to milrinone was depressed compared with the controls. However, when cAMP production was stimulated by pretreatment with forskolin, the response of the myopathic muscles to milrinone was improved. Our findings provide direct evidence that abnormal [Ca2+]i handling is an important cause of contractile dysfunction in dogs with pacing-induced heart failure and suggest that deficient production of cAMP may be an important cause of these changes in excitation-contraction coupling.

Differences in force normalising procedures during submaximal anisometric contractions.

PubMed

Škarabot, Jakob; Ansdell, Paul; Brownstein, Callum; Howatson, Glyn; Goodall, Stuart; Durbaba, Rade

2018-05-26

Eccentric contractions are thought to require a unique neural activation strategy. However, due to greater intrinsic force generating capacity of muscle fibres during eccentric contraction, the understanding of neural modulation of different contraction types during submaximal contractions may be impeded by the force normalisation procedure employed. In the present experiment, subjects performed maximal isometric dorsiflexion at shorter (80°), intermediate (90°) and longer (100°) muscle lengths, and maximal concentric and eccentric contractions. Thereafter, submaximal concentric and eccentric contractions were performed normalised to either isometric maximum at 90° (ISO), contraction type specific maximum (CTS) or muscle length specific maximum (MLS). When using ISO or MLS for normalisation, mean submaximal eccentric torque levels were significantly lower when compared to CTS normalisation (11 and 7% lower compared to CTS; p = 0.003 and p = 0.018 for ISO and MLS, respectively). These experimentally observed differences closely matched those expected from the predictive model. During submaximal concentric contraction, mean torque levels were similar between ISO and CTS normalisation with similar discrepancies noted in EMG activity. These findings suggest that normalising to ISO and MLS might not be accurate for assessment and prescription of submaximal eccentric contractions. Copyright © 2018 Elsevier Ltd. All rights reserved.

Dilatant effect enhancers for silica dispersions in poly(propylene glycols).

PubMed

Orawiec, Marcin; Kaczorowski, Marcin; Rokicki, Gabriel

2018-05-29

Shear thickening fluids have found many applications in energy damping materials such as sports guards and liquid body armors. Therefore, an additive which could tailor the dilatant properties of such fluids without significantly affecting other properties, especially zero shear viscosity, could significantly increase the versatility of protective materials based on shear thickening fluids. In this paper, poly(propylene glycols) (PPGs) diacetates are investigated as dilatant effect enhancers for nano-silica dispersions in poly(propylene glycols). The influence of the modifiers on rheological properties of the dispersion is studied and discussed. Additionally, FTIR and rheological properties measurements are conducted in order to determine relative interactions strength between hydroxyl groups of PPGs and silica and carbonyl groups of PPG diacetates. Our findings suggest that the relative attractive interaction strength in studied systems can be arranged in the following order: COCO < COOH < OHOH. Therefore, the addition of PPG diacetate hinders the attractive interactions between liquid and solid. We report that the addition of diacetates can lead both to enhancement and deterioration of dilatant effect depending on the concentration of the modifier and its chain length. Based on conducted measurements and literature data, mechanism explaining that phenomenon is suggested. As a result, we propose an easy to make and cheap dilatant effect enhancer for widely used shear thickening fluids which, when used in small amounts (1-2.5%), raises the viscosity jump drastically. Additionally, the presence of the modifier does not significantly affect the zero shear viscosity of the shear thickening fluid. Copyright © 2018 Elsevier Inc. All rights reserved.

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.

Contraction dynamics and function of the muscle-tendon complex depend on the muscle fibre-tendon length ratio: a simulation study.

PubMed

Mörl, Falk; Siebert, Tobias; Häufle, Daniel

2016-02-01

Experimental studies show different muscle-tendon complex (MTC) functions (e.g. motor or spring) depending on the muscle fibre-tendon length ratio. Comparing different MTC of different animals examined experimentally, the extracted MTC functions are biased by, for example, MTC-specific pennation angle and fibre-type distribution or divergent experimental protocols (e.g. influence of temperature or stimulation on MTC force). Thus, a thorough understanding of variation of these inner muscle fibre-tendon length ratios on MTC function is difficult. In this study, we used a hill-type muscle model to simulate MTC. The model consists of a contractile element (CE) simulating muscle fibres, a serial element (SE) as a model for tendon, and a parallel elastic element (PEE) modelling tissue in parallel to the muscle fibres. The simulation examines the impact of length variations of these components on contraction dynamics and MTC function. Ensuring a constant overall length of the MTC by L(MTC) = L(SE) + L(CE), the SE rest length was varied over a broad physiological range from 0.1 to 0.9 MTC length. Five different MTC functions were investigated by simulating typical physiological experiments: the stabilising function with isometric contractions, the motor function with contractions against a weight, the capability of acceleration with contractions against a small inertial mass, the braking function by decelerating a mass, and the spring function with stretch-shortening cycles. The ratio of SE and CE mainly determines the MTC function. MTC with comparably short tendon generates high force and maximal shortening velocity and is able to produce maximal work and power. MTC with long tendon is suitable to store and release a maximum amount of energy. Variation of muscle fibre-tendon ratio yielded two peaks for MTC's force response for short and long SE lengths. Further, maximum work storage capacity of the SE is at long relL(SE,0). Impact of fibre-tendon length ratio on MTC functions will be discussed. Considering a constant set of MTC parameters, quantitative changes in MTC performance (work, stiffness, force, energy storage, dissipation) depending on varying muscle fibre-tendon length ratio were provided, which enables classification and grading of different MTC designs.

Isolated Effect of Geometry on Mitral Valve Function for In-Silico Model Development

PubMed Central

Siefert, Andrew William; Rabbah, Jean-Pierre Michel; Saikrishnan, Neelakantan; Kunzelman, Karyn Susanne; Yoganathan, Ajit Prithivaraj

2013-01-01

Computational models for the heart’s mitral valve (MV) exhibit several uncertainties which may be reduced by further developing these models using ground-truth data sets. The present study generated a ground-truth data set by quantifying the effects of isolated mitral annular flattening, symmetric annular dilatation, symmetric papillary muscle displacement, and asymmetric papillary muscle displacement on leaflet coaptation, mitral regurgitation (MR), and anterior leaflet strain. MVs were mounted in an in vitro left heart simulator and tested under pulsatile hemodynamics. Mitral leaflet coaptation length, coaptation depth, tenting area, MR volume, MR jet direction, and anterior leaflet strain in the radial and circumferential directions were successfully quantified for increasing levels of geometric distortion. From these data, increasing levels of isolated papillary muscle displacement resulted in the greatest mean change in coaptation depth (70% increase), tenting area (150% increase), and radial leaflet strain (37% increase) while annular dilatation resulted in the largest mean change in coaptation length (50% decrease) and regurgitation volume (134% increase). Regurgitant jets were centrally located for symmetric annular dilatation and symmetric papillary muscle displacement. Asymmetric papillary muscle displacement resulted in asymmetrically directed jets. Peak changes in anterior leaflet strain in the circumferential direction were smaller and exhibited non-significant differences across the tested conditions. When used together, this ground-truth data may be used to parametrically evaluate and develop modeling assumptions for both the MV leaflets and subvalvular apparatus. This novel data may improve MV computational models and provide a platform for the development of future surgical planning tools. PMID:24059354

Dilation of epicardial coronary arteries by the G protein-coupled estrogen receptor agonists G-1 and ICI 182,780.

PubMed

Meyer, Matthias R; Baretella, Oliver; Prossnitz, Eric R; Barton, Matthias

2010-01-01

Endogenous estrogens protect from coronary artery disease in premenopausal women, but the mechanisms involved are only partly understood. This study investigated whether activation of the novel G protein-coupled estrogen receptor (GPER, formerly known as GPR30) affects coronary artery tone, and whether this is affected by concomitant blockade of estrogen receptors (ER) alpha and beta. Rings of epicardial porcine coronary arteries suspended in organ chambers were precontracted with prostaglandin F(2)alpha, and direct effects of G-1 (GPER agonist) and ICI 182,780 (GPER agonist and ERalpha/ERbeta antagonist) were determined. In addition, indirect effects on contractility to endothelin-1 and serotonin (a vasoconstrictor released from aggregating platelets during acute myocardial infarction) were assessed. ICI 182,780 and G-1 caused acute dilation of coronary arteries to a comparable degree (p < 0.05 vs. solvent control). Both GPER agonists attenuated contractions to endothelin-1 (p < 0.05 vs. ethanol), but not to serotonin (n.s.). In summary, these findings provide evidence for direct and indirect coronary artery dilator effects of GPER independent of ERalpha and ERbeta, and are the first demonstration of arterial vasodilation in response to ICI 182,780. Copyright 2010 S. Karger AG, Basel.

Characterization of the canine desmin (DES) gene and evaluation as a candidate gene for dilated cardiomyopathy in the Dobermann.

PubMed

Stabej, Polona; Imholz, Sandra; Versteeg, Serge A; Zijlstra, Carla; Stokhof, Arnold A; Domanjko-Petric, Aleksandra; Leegwater, Peter A J; van Oost, Bernard A

2004-10-13

Canine-dilated cardiomyopathy (DCM) in dogs is a disease of the myocardium associated with dilatation and impaired contraction of the ventricles and is suspected to have a genetic cause. A missense mutation in the desmin gene (DES) causes DCM in a human family. Human DCM closely resembles the canine disease. In the present study, we evaluated whether DES gene mutations are responsible for DCM in Dobermann dogs. We have isolated bacterial artificial chromosome clones (BACs) containing the canine DES gene and determined the chromosomal location by fluorescence in situ hybridization (FISH). Using data deposited in the NCBI trace archive and GenBank, the canine DES gene DNA sequence was assembled and seven single nucleotide polymorphisms (SNPs) were identified. From the canine DES gene BAC clones, a polymorphic microsatellite marker was isolated. The microsatellite marker and four informative desmin SNPs were typed in a Dobermann family with frequent DCM occurrence, but the disease phenotype did not associate with a desmin haplotype. We concluded that mutations in the DES gene do not play a role in Dobermann DCM. Availability of the microsatellite marker, SNPs and DNA sequence reported in this study enable fast evaluation of the DES gene as a DCM candidate gene in other dog breeds with DCM occurrence.

Patient-Specific Induced Pluripotent Stem Cell as a Model for Familial Dilated Cardiomyopathy

PubMed Central

Sun, Ning; Yazawa, Masayuki; Liu, Jianwei; Han, Leng; Sanchez-Freire, Veronica; Abilez, Oscar J.; Navarrete, Enrique G.; Hu, Shijun; Wang, Li; Lee, Andrew; Pavlovic, Aleksandra; Lin, Shin; Chen, Rui; Hajjar, Roger J.; Snyder, Michael P.; Dolmetsch, Ricardo E.; Butte, Manish J.; Ashley, Euan A.; Longaker, Michael T.; Robbins, Robert C.; Wu, Joseph C.

2013-01-01

Dilated cardiomyopathy (DCM) is the most common cardiomyopathy, characterized by ventricular dilatation, systolic dysfunction, and progressive heart failure. DCM is the most common diagnosis leading to heart transplantation and places a significant burden on healthcare worldwide. The advent of induced pluripotent stem cells (iPSCs) offers an exceptional opportunity for creating disease-specific models, investigating underlying mechanisms, and optimizing therapy. Here we generated cardiomyocytes (CMs) from iPSCs derived from patients of a DCM family carrying a point mutation (R173W) in the gene encoding sarcomeric protein cardiac troponin T. Compared to the control healthy individuals in the same family cohort, DCM iPSC-CMs exhibited altered Ca2+ handling, decreased contractility, and abnormal sarcomeric α-actinin distribution. When stimulated with β-adrenergic agonist, DCM iPSC-CMs showed characteristics of failure such as reduced beating rates, compromised contraction, and significantly more cells with abnormal sarcomeric α-actinin distribution. β-adrenergic blocker treatment and over-expression of sarcoplasmic reticulum Ca2+ ATPase (Serca2a) improved DCM iPSC-CMs function. Our study demonstrated that human DCM iPSC-CMs recapitulated to some extent the disease phenotypes morphologically and functionally, and thus can serve as a useful platform for exploring molecular and cellular mechanisms and optimizing treatment of this particular disease. PMID:22517884

A two-phase debris-flow model that includes coupled evolution of volume fractions, granular dilatancy, and pore-fluid pressure

USGS Publications Warehouse

George, David L.; Iverson, Richard M.

2011-01-01

Pore-fluid pressure plays a crucial role in debris flows because it counteracts normal stresses at grain contacts and thereby reduces intergranular friction. Pore-pressure feedback accompanying debris deformation is particularly important during the onset of debrisflow motion, when it can dramatically influence the balance of forces governing downslope acceleration. We consider further effects of this feedback by formulating a new, depth-averaged mathematical model that simulates coupled evolution of granular dilatancy, solid and fluid volume fractions, pore-fluid pressure, and flow depth and velocity during all stages of debris-flow motion. To illustrate implications of the model, we use a finite-volume method to compute one-dimensional motion of a debris flow descending a rigid, uniformly inclined slope, and we compare model predictions with data obtained in large-scale experiments at the USGS debris-flow flume. Predictions for the first 1 s of motion show that increasing pore pressures (due to debris contraction) cause liquefaction that enhances flow acceleration. As acceleration continues, however, debris dilation causes dissipation of pore pressures, and this dissipation helps stabilize debris-flow motion. Our numerical predictions of this process match experimental data reasonably well, but predictions might be improved by accounting for the effects of grain-size segregation.

Feed artery role in blood flow control to rat hindlimb skeletal muscles.

PubMed Central

Williams, D A; Segal, S S

1993-01-01

1. Vasomotor tone and reactivity were investigated in feed arteries of the extensor digitorum longus and soleus muscles. Feed arteries are located external to the muscle and give rise to the microcirculation within each muscle. Resting diameter was smaller in feed arteries of the soleus muscle. 2. Feed arteries of both muscles dilated to similar peak values with sodium nitroprusside. 3. Micropressure measurements demonstrated resistance to blood flow in the feed arteries supplying both muscles. Feed arteries supplying soleus muscle demonstrated greater resistance to blood flow compared to feed arteries of extensor digitorum longus muscle. 4. Greater resting tone and larger pressure drop for feed arteries of soleus muscle suggest greater range of flow control compared to feed arteries of extensor digitorum longus muscle. 5. In both muscles, feed artery diameter increased with muscle contraction (functional dilatation) and in response to transient ischaemia (reactive dilatation). The magnitude of these responses varied between muscles. 6. Feed arteries are active sites of blood flow control in extensor digitorum longus and soleus muscles of the rat. These muscles differ in fibre type and recruitment properties. Differences in feed artery reactivity may contribute to differences in blood flow between these muscles observed at rest and during exercise. Images Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:8246199

Agenesis of the gallbladder with hypoplastic cystic duct diagnosed at laparoscopy.

PubMed

Kwon, A-Hon; Yanagimoto, Hiroaki; Matsui, Yoichi; Imamura, Atsushi

2006-08-01

An 86-year-old man was admitted to our department with complaints of intermittent upper abdominal pain. Ultrasonography of the abdomen showed dilated extrahepatic bile ducts containing stones; however, the gallbladder was not clearly identified. Magnetic resonance cholangiopancreatography showed dilated extrahepatic ducts and choledocholithiasis without gallbladder visualization. The stone extraction was performed with endoscopic sphincterotomy. Three-dimensional images using spiral-computed tomography after intravenous-infusion cholangiography clearly demonstrated an obstruction of the cystic duct. The patient was scheduled for laparoscopic cholecystectomy. At laparoscopy, the gallbladder fossa was not identified on the undersurface of the liver. Despite a thorough examination of the intrahepatic (left-sided within the lesser omentum), retroperitoneal, retrohepatic (within the falciform ligament), retroduodenal, and retropancreatic areas using laparoscopic ultrasonography, the gallbladder was not found. After careful dissection of the hepatoduodenal ligament, the dilated extrahepatic bile duct and a 1-cm length of hypoplastic cystic duct were found. Gallbladder agenesis is usually accompanied by the lack of the cystic duct. The present case is the third report of gallbladder agenesis with a patent or hypoplastic cystic duct.

High-Resolution Strain Analysis of the Human Heart with Fast-DENSE

NASA Astrophysics Data System (ADS)

Aletras, Anthony H.; Balaban, Robert S.; Wen, Han

1999-09-01

Single breath-hold displacement data from the human heart were acquired with fast-DENSE (fast displacement encoding with stimulated echoes) during systolic contraction at 2.5 × 2.5 mm in-plane resolution. Encoding strengths of 0.86-1.60 mm/π were utilized in order to extend the dynamic range of the phase measurements and minimize effects of physiologic and instrument noise. The noise level in strain measurements for both contraction and dilation corresponded to a strain value of 2.8%. In the human heart, strain analysis has sufficient resolution to reveal transmural variation across the left ventricular wall. Data processing required minimal user intervention and provided a rapid quantitative feedback. The intrinsic temporal integration of fast-DENSE achieves high accuracy at the expense of temporal resolution.

Energy cost of isometric force production after active shortening in skinned muscle fibres.

PubMed

Joumaa, Venus; Fitzowich, Alex; Herzog, Walter

2017-04-15

The steady-state isometric force after active shortening of a skeletal muscle is lower than the purely isometric force at the corresponding length. This property of skeletal muscle is known as force depression. The purpose of this study was to investigate whether the energy cost of force production at the steady state after active shortening was reduced compared with the energy cost of force production for a purely isometric contraction performed at the corresponding length (same length, same activation). Experiments were performed in skinned fibres isolated from rabbit psoas muscle. Skinned fibres were actively shortened from an average sarcomere length of 3.0 µm to an average sarcomere length of 2.4 µm. Purely isometric reference contractions were performed at an average sarcomere length of 2.4 µm. Simultaneously with the force measurements, the ATP cost was measured during the last 30 s of isometric contractions using an enzyme-coupled assay. Stiffness was calculated during a quick stretch-release cycle of 0.2% fibre length performed once the steady state had been reached after active shortening and during the purely isometric reference contractions. Force and stiffness following active shortening were decreased by 10.0±1.8% and 11.0±2.2%, respectively, compared with the isometric reference contractions. Similarly, ATPase activity per second (not normalized to the force) showed a decrease of 15.6±3.0% in the force-depressed state compared with the purely isometric reference state. However, ATPase activity per second per unit of force was similar for the isometric contractions following active shortening (28.7±2.4 mmol l -1  mN -1  s mm 3 ) and the corresponding purely isometric reference contraction (30.9±2.8 mmol l -1  mN -1  s mm 3 ). Furthermore, the reduction in absolute ATPase activity per second was significantly correlated with force depression and stiffness depression. These results are in accordance with the idea that force depression following active shortening is primarily caused by a decrease in the proportion of attached cross-bridges. Furthermore, these findings, along with previously reported results showing a decrease in ATP consumption per unit of force after active muscle stretching, suggest that the mechanisms involved in the steady-state force after active muscle shortening and active muscle lengthening are of distinctly different origin. © 2017. Published by The Company of Biologists Ltd.

A thixotropic effect in contracting rabbit psoas muscle: prior movement reduces the initial tension response to stretch

PubMed Central

Campbell, Kenneth S; Moss, Richard L

2000-01-01

Paired ramp stretches and releases (‘triangular length changes’, typically 0.04 ± 0.09L0 s−1; mean ±s.e.m.) were imposed on permeabilised rabbit psoas fibre segments under sarcomere length control. In actively contracting fibres, the tension response to stretch was biphasic; tension rose more rapidly during the first 0.005L0 of the imposed stretch than thereafter. Tension also dropped in a biphasic manner during shortening, and at the end of the length change was reduced below the steady state. If a second triangular length change was imposed shortly after the first, tension rose less sharply during the initial phase of lengthening, i.e. the stiffness of the muscle during the initial phase of the response was reduced in the second stretch. This is a thixotropic effect. If a third triangular length change was imposed on the muscle, the response was the same as that to the second. The time required to recover the original tension response was measured by varying the interval between triangular length changes. Recovery to steady state occurred at a rate of ∼1 s−1. The stiffness of the muscle during the initial phase of the response scaled with the developed tension in pCa (=−log10[Ca2+]) solutions ranging from 6.3 (minimal activation) to 4.5 (saturating effect). The relative thixotropic reduction in stiffness measured using paired length changes was independent of the pCa of the activating solution. The thixotropic behaviour of contracting skeletal muscle can be explained by a cross-bridge model of muscle contraction in which the number of attached cross-bridges is temporarily reduced following an imposed movement. PMID:10835052

Vardenafil inhibiting parasympathetic function of tracheal smooth muscle.

PubMed

Lee, Fei-Peng; Chao, Pin-Zhir; Wang, Hsing-Won

2018-07-01

Levitra, a phosphodiesterase-5 (PDE5) inhibitor, is the trade name of vardenafil. Nowadays, it is applied to treatment of erectile dysfunction. PDE5 inhibitors are employed to induce dilatation of the vascular smooth muscle. The effect of Levitra on impotency is well known; however, its effect on the tracheal smooth muscle has rarely been explored. When administered for sexual symptoms via oral intake or inhalation, Levitra might affect the trachea. This study assessed the effects of Levitra on isolated rat tracheal smooth muscle by examining its effect on resting tension of tracheal smooth muscle, contraction caused by 10 -6  M methacholine as a parasympathetic mimetic, and electrically induced tracheal smooth muscle contractions. The results showed that adding methacholine to the incubation medium caused the trachea to contract in a dose-dependent manner. Addition of Levitra at doses of 10 -5  M or above elicited a significant relaxation response to 10 -6  M methacholine-induced contraction. Levitra could inhibit electrical field stimulation-induced spike contraction. It alone had minimal effect on the basal tension of the trachea as the concentration increased. High concentrations of Levitra could inhibit parasympathetic function of the trachea. Levitra when administered via oral intake might reduce asthma attacks in impotent patients because it might inhibit parasympathetic function and reduce methacholine-induced contraction of the tracheal smooth muscle. Copyright © 2018. Published by Elsevier Taiwan LLC.

48 CFR 215.404-71-3 - Contract type risk and working capital adjustment.

Code of Federal Regulations, 2014 CFR

2014-10-01

... varying contract types. The working capital adjustment is an adjustment added to the profit objective for... Base (item 20) Profit objective 24. CONTRACT type risk (1) (2) (3) Cost financed Length factor Interest... money. (3) Multiply (1) by (2). (4) Only complete this block when the prospective contract is a fixed...

48 CFR 215.404-71-3 - Contract type risk and working capital adjustment.

Code of Federal Regulations, 2013 CFR

2013-10-01

... varying contract types. The working capital adjustment is an adjustment added to the profit objective for... Base (item 20) Profit objective 24. CONTRACT type risk (1) (2) (3) Cost financed Length factor Interest... money. (3) Multiply (1) by (2). (4) Only complete this block when the prospective contract is a fixed...

48 CFR 215.404-71-3 - Contract type risk and working capital adjustment.

Code of Federal Regulations, 2012 CFR

2012-10-01

... varying contract types. The working capital adjustment is an adjustment added to the profit objective for... Base (item 20) Profit objective 24. CONTRACT type risk (1) (2) (3) Cost financed Length factor Interest... money. (3) Multiply (1) by (2). (4) Only complete this block when the prospective contract is a fixed...

Percutaneous Dilational Tracheotomy in Solid-Organ Transplant Recipients.

PubMed

Ozdemirkan, Aycan; Ersoy, Zeynep; Zeyneloglu, Pinar; Gedik, Ender; Pirat, Arash; Haberal, Mehmet

2015-11-01

Solid-organ transplant recipients may require percutaneous dilational tracheotomy because of prolonged mechanical ventilation or airway issues, but data regarding its safety and effectiveness in solid-organ transplant recipients are scarce. Here, we evaluated the safety, effectiveness, and benefits in terms of lung mechanics, complications, and patient comfort of percutaneous dilational tracheotomy in solid-organ transplant recipients. Medical records from 31 solid-organ transplant recipients (median age of 41.0 years [interquartile range, 18.0-53.0 y]) who underwent percutaneous dilational tracheotomy at our hospital between January 2010 and March 2015 were analyzed, including primary diagnosis, comorbidities, duration of orotracheal intubation and mechanical ventilation, length of intensive care unit and hospital stays, the time interval between transplant to percutaneous dilational tracheotomy, Acute Physiology and Chronic Health Evaluation II score, tracheotomy-related complications, and pulmonary compliance and ratio of partial pressure of arterial oxygen to fraction of inspired oxygen. The median Acute Physiology and Chronic Health Evaluation II score on admission was 24.0 (interquartile range, 18.0-29.0). The median interval from transplant to percutaneous dilational tracheotomy was 105.5 days (interquartile range, 13.0-2165.0 d). The only major complication noted was left-sided pneumothorax in 1 patient. There were no significant differences in ratio of partial pressure of arterial oxygen to fraction of inspired oxygen before and after procedure (170.0 [interquartile range, 102.2-302.0] vs 210.0 [interquartile range, 178.5-345.5]; P = .052). However, pulmonary compliance results preprocedure and postprocedure were significantly different (0.020 L/cm H2O [interquartile range, 0.015-0.030 L/cm H2O] vs 0.030 L/cm H2O [interquartile range, 0.020-0.041 L/cm H2O); P = .001]). Need for sedation significantly decreased after tracheotomy (from 17 patients [54.8%] to 8 patients [25.8%]; P = .004]). Percutaneous dilational tracheotomy with bronchoscopic guidance is an efficacious and safe technique for maintaining airways in solidorgan transplant recipients who require prolonged mechanical ventilation, resulting in possible improvements in ventilatory mechanics and patient comfort.

Labial flap vaginoplasty with sacrospinous fixation.

PubMed

Murthy, Chandrashekar; Ashok, Kiran; Kalal, Susheel Kumar

2010-01-01

We present a case of congenital absence of Vagina which was treated by reconstruction of the vagina using vascular labial flaps. Furthermore, we anchored the neo-vagina to the Sacro-spinous ligament on either side. The aim of the attachment to the sacro-spinous ligament is to provide a durable apical support and to give an immediate, good vaginal length. Various techniques have been described for the construction of Neo-vagina. Except for sigmoid vaginoplasty, most other procedures are associated with a significant risk of post-operative restenosis, for which prolonged dilatation is necessary. Attaching to the sacro-spinous ligament gives the vagina good depth and, to some extent, decreases the risk of re-stenosis. This technique is simpler, does not require sophisticated instruments or prolonged post operative dilatation and is particularly suitable for under-developed countries.

48 CFR 16.104 - Factors in selecting contract types.

Code of Federal Regulations, 2010 CFR

2010-10-01

... provide the bases for negotiating contract pricing arrangements. It is essential that the uncertainties... performance or length of production run. In times of economic uncertainty, contracts extending over a relatively long period may require economic price adjustment terms. (g) Contractor's technical capability and...

The shape of uterine contractions and labor progress in the spontaneous active labor.

PubMed

Ebrahimzadeh Zagami, Samira; Golmakani, Nahid; Saadatjoo, Seyyed Ali-Reza; Ghomian, Nayyereh; Baghbani, Behjat

2015-03-01

Dystocia is the most common indication of primary cesarean section. The most common cause of dystocia is uterine dysfunction. In prolonged labor, more attention is usually paid to the fetus and pelvis rather than to the role of uterine contractions in a delivery. Therefore, we decided to determine the relationship between the labor progress and uterine contractions shapes. In this cross-sectional study, 200 primiparous women participated having a single pregnancy and cephalic presentation. Uterus contractions were recorded using electronic fetal monitoring at the beginning of the active phase of labor (dilatation 3-5 cm) for 30 min. Fall to rise (F:R) ratio was calculated by determining the duration of returning from a contraction peak to its baseline (fall) and the duration of the rise time from baseline to peak (rise) in two groups. The data were analyzed using t-test and Chi-square test. In this study, 162 women had a normal delivery and 38 women had a cesarean (CS) delivery due to the lack of labor progress. The average F:R ratio was 1.13±0.193 seconds in the vaginal delivery group and 1.64±0.301 seconds in the CS group. This difference was statistically significant (P<0.001). The frequency of contractions in the vaginal delivery group was more than the CS group (P=0.008). Our findings demonstrated that uterine contractions shapes change; and F:R ratio was higher in the group that lacked labor progress. Therefore, contraction shapes can be used to predict the labor progress.

Isolated Main Pancreatic Duct Dilatation: CT Differentiation Between Benign and Malignant Causes.

PubMed

Kim, Se Woo; Kim, Se Hyung; Lee, Dong Ho; Lee, Sang Min; Kim, Yeon Soo; Jang, Jin Young; Han, Joon Koo

2017-11-01

The purpose of this study is to retrospectively evaluate the differential CT features of isolated benign and malignant main pancreatic duct (MPD) dilatation and to investigate whether the diagnostic performance of radiologists can be improved with knowledge of these differential CT features. Forty-one patients who had isolated MPD dilatation without any visible mass on CT from January 2000 to October 2016 were retrospectively enrolled in the study. Two radiologists reviewed CT images in consensus for the location, shape (smooth vs abrupt), length of transition, dilated pancreatic duct (PD) diameter, presence of duct penetrating sign, parenchymal atrophy, attenuation difference, associated pancreatitis, calcification, PD or common bile duct (CBD) enhancement, and perilesional cyst. The chi-square test, Fisher exact test, and t test were used to find the differential CT features of benign and malignant MPD dilatation. Two successive review sessions for differentiation between the two disease entities were then independently performed by three other reviewers with differing expertise, with the use of a 5-point confidence scale. The first session provided no information for differentiation; however, reviewers were aware of the results of univariate analyses in the second session. The diagnostic performance of the radiologists was evaluated using a pairwise comparison of ROC curves. A total of 19 benign and 22 malignant MPD dilatations were identified. In patients with benign MPD dilatation, transition areas were frequently located in the head (57.9% [11/19] vs 13.6% [3/22], p = 0.003) and showed significantly shorter (< 6.1 mm) (78.9% [15/19] vs 9.1% [2/22], p < 0.0001) and smooth transition (89.5% [17/19] vs 9.1% [2/22], p < 0.0001). Duct penetrating sign was exclusively observed in patients with benign MPD dilatation (73.7% [14/19] vs 0% [0/22], p < 0.0001). In contrast, malignant MPD dilatation frequently was accompanied by attenuation difference (63.6% [14/22] vs 10.5% [2/19], p = 0.001) and associated PD or CBD enhancement (36.4% [8/22] vs 0% [0/19], p = 0.003). The AUC values of three reviewers significantly increased from 0.653, 0.587, and 0.884 to 0.864, 0.964, and 0.908, respectively, with knowledge of significant CT features (p = 0.013, p < 0.0001, and p = 0.701, respectively). Distal, long (≥ 6.1 mm), and abrupt transition, the absence of duct penetrating sign, and the presence of attenuation difference and PD or CBD enhancement were highly suggestive CT findings for differentiation of malignant from benign MPD dilatation. The diagnostic performance of radiologists with regard to differentiation was significantly improved with knowledge of these highly suggestive CT criteria.

Modeling Treatment Response for Lamin A/C Related Dilated Cardiomyopathy in Human Induced Pluripotent Stem Cells.

PubMed

Lee, Yee-Ki; Lau, Yee-Man; Cai, Zhu-Jun; Lai, Wing-Hon; Wong, Lai-Yung; Tse, Hung-Fat; Ng, Kwong-Man; Siu, Chung-Wah

2017-07-28

Precision medicine is an emerging approach to disease treatment and prevention that takes into account individual variability in the environment, lifestyle, and genetic makeup of patients. Patient-specific human induced pluripotent stem cells hold promise to transform precision medicine into real-life clinical practice. Lamin A/C (LMNA)-related cardiomyopathy is the most common inherited cardiomyopathy in which a substantial proportion of mutations in the LMNA gene are of nonsense mutation. PTC124 induces translational read-through over the premature stop codon and restores production of the full-length proteins from the affected genes. In this study we generated human induced pluripotent stem cells-derived cardiomyocytes from patients who harbored different LMNA mutations (nonsense and frameshift) to evaluate the potential therapeutic effects of PTC124 in LMNA -related cardiomyopathy. We generated human induced pluripotent stem cells lines from 3 patients who carried distinctive mutations (R225X, Q354X, and T518fs) in the LMNA gene. The cardiomyocytes derived from these human induced pluripotent stem cells lines reproduced the pathophysiological hallmarks of LMNA -related cardiomyopathy. Interestingly, PTC124 treatment increased the production of full-length LMNA proteins in only the R225X mutant, not in other mutations. Functional evaluation experiments on the R225X mutant further demonstrated that PTC124 treatment not only reduced nuclear blebbing and electrical stress-induced apoptosis but also improved the excitation-contraction coupling of the affected cardiomyocytes. Using cardiomyocytes derived from human induced pluripotent stem cells carrying different LMNA mutations, we demonstrated that the effect of PTC124 is codon selective. A premature stop codon UGA appeared to be most responsive to PTC124 treatment. © 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Structural basis for gating and activation of RyR1

PubMed Central

des Georges, Amédée; Clarke, Oliver B.; Zalk, Ran; Yuan, Qi; Condon, Kendall J.; Grassucci, Robert A.; Hendrickson, Wayne A.; Marks, Andrew R.; Frank, Joachim

2016-01-01

Summary The type-1 ryanodine receptor (RyR1) is an intracellular calcium (Ca2+) release channel required for skeletal muscle contraction. Here we present cryo-EM reconstructions of RyR1 in multiple functional states revealing the structural basis of channel gating and ligand-dependent activation. Binding sites for the channel activators Ca2+, ATP and caffeine were identified at interdomain interfaces of the C-terminal domain. Either ATP or Ca2+ alone induce conformational changes in the cytoplasmic assembly (‘priming’), without pore dilation. In contrast, in the presence of all three activating ligands, high-resolution reconstructions of open and closed states of RyR1 were obtained from the same sample, enabling analyses of conformational changes associated with gating. Gating involves global conformational changes in the cytosolic assembly accompanied by local changes in the transmembrane domain, which include bending of the S6 transmembrane segment and consequent pore dilation, displacement and deformation of the S4-S5 linker, and conformational changes in the pseudo-voltage-sensor domain. PMID:27662087

Loss of atrial contractility is primary cause of atrial dilatation during first days of atrial fibrillation.

PubMed

Schotten, Ulrich; de Haan, Sunniva; Neuberger, Hans-Ruprecht; Eijsbouts, Sabine; Blaauw, Yuri; Tieleman, Robert; Allessie, Maurits

2004-11-01

Atrial fibrillation (AF) induces a progressive dilatation of the atria which in turn might promote the arrhythmia. The mechanism of atrial dilatation during AF is not known. To test the hypothesis that loss of atrial contractile function is a primary cause of atrial dilatation during the first days of AF, eight goats were chronically instrumented with epicardial electrodes, a pressure transducer in the right atrium, and piezoelectric crystals to measure right atrial diameter. AF was induced with the use of repetitive burst pacing. Atrial contractility was assessed during sinus rhythm, atrial pacing (160-, 300-, and 400-ms cycle length), and electrically induced AF. The compliance of the fibrillating right atrium was measured during unloading the atria with diuretics and loading with 1 liter of saline. All measurements were repeated after 6, 12, and 24 h of AF and then once a day during the first 5 days of AF. Recovery of the observed changes after spontaneous cardioversion was also studied. After 5 days of AF, atrial contractility during sinus rhythm or slow atrial pacing was greatly reduced. During rapid pacing (160 ms) or AF, the amplitude of the atrial pressure waves had declined to 20% of control. The compliance of the fibrillating atria increased twofold, whereas the right atrial pressure was unchanged. As a result, the mean right atrial diameter increased by approximately 12%. All changes were reversible within 3 days of sinus rhythm. We conclude that atrial dilatation during the first days of AF is due to an increase in atrial compliance caused by loss of atrial contractility during AF. Atrial compliance and size are restored when atrial contractility recovers after cardioversion of AF.

Direct measurement of Vorticella contraction force by micropipette deflection.

PubMed

France, Danielle; Tejada, Jonathan; Matsudaira, Paul

2017-02-01

The ciliated protozoan Vorticella convallaria is noted for its exceptionally fast adenosine triphosphate-independent cellular contraction, but direct measurements of contractile force have proven difficult given the length scale, speed, and forces involved. We used high-speed video microscopy to image live Vorticella stalled in midcontraction by deflection of an attached micropipette. Stall forces correlate with both distance contracted and the resting stalk length. Estimated isometric forces range from 95 to 177 nanonewtons (nN), or 1.12 nN·μm -1 of the stalk. Maximum velocity and work are also proportional to distance contracted. These parameters constrain proposed biochemical/physical models of the contractile mechanism. © Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

Structural Changes in Isometrically Contracting Insect Flight Muscle Trapped following a Mechanical Perturbation

PubMed Central

Wu, Shenping; Liu, Jun; Perz-Edwards, Robert J.; Tregear, Richard T.; Winkler, Hanspeter; Franzini-Armstrong, Clara; Sasaki, Hiroyuki; Goldman, Yale E.; Reedy, Michael K.; Taylor, Kenneth A.

2012-01-01

The application of rapidly applied length steps to actively contracting muscle is a classic method for synchronizing the response of myosin cross-bridges so that the average response of the ensemble can be measured. Alternatively, electron tomography (ET) is a technique that can report the structure of the individual members of the ensemble. We probed the structure of active myosin motors (cross-bridges) by applying 0.5% changes in length (either a stretch or a release) within 2 ms to isometrically contracting insect flight muscle (IFM) fibers followed after 5–6 ms by rapid freezing against a liquid helium cooled copper mirror. ET of freeze-substituted fibers, embedded and thin-sectioned, provides 3-D cross-bridge images, sorted by multivariate data analysis into ∼40 classes, distinct in average structure, population size and lattice distribution. Individual actin subunits are resolved facilitating quasi-atomic modeling of each class average to determine its binding strength (weak or strong) to actin. ∼98% of strong-binding acto-myosin attachments present after a length perturbation are confined to “target zones” of only two actin subunits located exactly midway between successive troponin complexes along each long-pitch helical repeat of actin. Significant changes in the types, distribution and structure of actin-myosin attachments occurred in a manner consistent with the mechanical transients. Most dramatic is near disappearance, after either length perturbation, of a class of weak-binding cross-bridges, attached within the target zone, that are highly likely to be precursors of strong-binding cross-bridges. These weak-binding cross-bridges were originally observed in isometrically contracting IFM. Their disappearance following a quick stretch or release can be explained by a recent kinetic model for muscle contraction, as behaviour consistent with their identification as precursors of strong-binding cross-bridges. The results provide a detailed model for contraction in IFM that may be applicable to contraction in other types of muscle. PMID:22761792

Whole exome sequencing identified 1 base pair novel deletion in BCL2-associated athanogene 3 (BAG3) gene associated with severe dilated cardiomyopathy (DCM) requiring heart transplant in multiple family members.

PubMed

Rafiq, Muhammad Arshad; Chaudhry, Ayeshah; Care, Melanie; Spears, Danna A; Morel, Chantal F; Hamilton, Robert M

2017-03-01

Dilated cardiomyopathy (DCM) is characterized by dilation and impaired contraction of the left ventricle or both ventricles. Among hereditary DCM, the genetic causes are heterogeneous, and include mutations encoding cytoskeletal, nucleoskeletal, mitochondrial, and calcium-handling proteins. We report three severely affected males, in a four-generation pedigree, with DCM phenotype who underwent cardiac transplant. Cardiomegaly with marked biventricular dilation and fibrosis were noticeable histopathological findings. The affected males had tested negative on a 46-gene pancardiomyopathy panel. Whole Exome Sequencing (WES) was performed to reveal mutation in the gene responsible in generation of DCM phenotypes. The 1-bp (Chr10:121435979delC; c.913delC) novel heterozygous deletion in exon 4 of BAG3, was identified in three affected males, resulted in frame-shift and a premature termination codon (p.Met306-Stop) producing a truncated BAG3 protein lacking functionally important PXXP and BAG domains. WES data were further utilized to map 10 SNP markers around the discovered mutation to generate shared disease haplotype in all affected individuals encompassing 11 Mb on 10q25.3-26.2 harboring BAG3. Finally genotypes were inferred for the unavailable/deceased individuals in the pedigrees. Here we propose that Chr10:121435979delC in BAG3 is a causal mutation in these subjects. Our and earlier studies indicate that BAG3 mutations are associated with DCM phenotypes. BAG3 should be added to cardiomyopathy gene panels for screening of DCM patients, and patients previously considered gene elusive should undergo sequencing of the BAG3 gene. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

The Amount and Preferred Orientation of Simple-shear in a Deformation Tensor: Implications for Detecting Shear Zones and Faults with GPS

NASA Astrophysics Data System (ADS)

Johnson, A. M.; Griffiths, J. H.

2007-05-01

At the 2005 Fall Meeting of the American Geophysical Union, Griffiths and Johnson [2005] introduced a method of extracting from the deformation-gradient (and velocity-gradient) tensor the amount and preferred orientation of simple-shear associated with 2-D shear zones and faults. Noting the 2-D is important because the shear zones and faults in Griffiths and Johnson [2005] were assumed non-dilatant and infinitely long, ignoring the scissors- like action along strike associated with shear zones and faults of finite length. Because shear zones and faults can dilate (and contract) normal to their walls and can have a scissors-like action associated with twisting about an axis normal to their walls, the more general method of detecting simple-shear is introduced and called MODES "method of detecting simple-shear." MODES can thus extract from the deformation-gradient (and velocity- gradient) tensor the amount and preferred orientation of simple-shear associated with 3-D shear zones and faults near or far from the Earth's surface, providing improvements and extensions to existing analytical methods used in active tectonics studies, especially strain analysis and dislocation theory. The derivation of MODES is based on one definition and two assumptions: by definition, simple-shear deformation becomes localized in some way; by assumption, the twirl within the deformation-gradient (or the spin within the velocity-gradient) is due to a combination of simple-shear and twist, and coupled with the simple- shear and twist is a dilatation of the walls of shear zones and faults. The preferred orientation is thus the orientation of the plane containing the simple-shear and satisfying the mechanical and kinematical boundary conditions. Results from a MODES analysis are illustrated by means of a three-dimensional diagram, the cricket- ball, which is reminiscent of the seismologist's "beach ball." In this poster, we present the underlying theory of MODES and illustrate how it works by analyzing the three- dimensional displacements measured with the Global Positioning System across the 1999 Chi-Chi earthquake ground rupture in Taiwan. In contrast to the deformation zone in the upper several meters of the ground below the surface detected by Yu et al. [2001], MODES determines the orientation and direction of shift of a shear zone representing the earthquake fault within the upper several hundred or thousand meters of ground below the surface. Thus, one value of the MODES analysis in this case is to provide boundary conditions for dislocation solutions for the subsurface shape of the main rupture during the earthquake.

Aortic Elongation and Stanford B Dissection: The Tübingen Aortic Pathoanatomy (TAIPAN) Project.

PubMed

Lescan, M; Veseli, K; Oikonomou, A; Walker, T; Lausberg, H; Blumenstock, G; Bamberg, F; Schlensak, C; Krüger, T

2017-08-01

Aortic elongation has not yet been considered as a potential risk factor for Stanford type B dissection (TBD). The role of both aortic elongation and dilatation in patients with TBD was evaluated. The aortic morphology of a healthy control group (n = 236) and patients with TBD (n = 96) was retrospectively examined using three dimensional computed tomography imaging. Curved multiplanar reformats were used to examine aortic diameters at defined landmarks and aortic segment lengths. Diameters at all landmarks were significantly larger in the TBD group. The greatest diameter difference (56%) was measured in dissected descending aortas (p < .001). The segment with the most considerable difference between the study groups with regard to elongation was the non-dissected aortic arch of patients with TBD (36%; p < .001). Elongation in the aortic arch was accompanied by a diameter increase of 21% (p < .001). In receiver-operating curve analysis, the area under the curve was .85 for the diameter and .86 for the length of the aortic arch. In addition to dilatation, aortic arch elongation is associated with the development of TBD. The diameter and length of the non-dissected aortic arch may be predictive for TBD and may possibly be used for risk assessment in the future. This study provides the basis for further prospective evaluation of these parameters. Copyright © 2017 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

Materials fatigue initiates eccentric contraction-induced injury in rat soleus muscle.

PubMed Central

Warren, G L; Hayes, D A; Lowe, D A; Prior, B M; Armstrong, R B

1993-01-01

1. The initiation of exercise-induced muscle injury is thought to be the result of high tensile stresses produced in the muscle during eccentric contractions. Materials science theory suggests that high tensile stresses could initiate the injury during the first eccentric contraction (normal stress theory) or after multiple eccentric contractions (materials fatigue). It was the objective of this study to investigate the two possibilities. 2. Rat soleus muscles (n = 66; 11 protocols with 6 muscles per protocol) were isolated, placed in an oxygenated Krebs-Ringer buffer at 37 degrees C, and baseline measurements were made. The muscle then performed an injury protocol which consisted of between zero and ten eccentric contractions (muscle starting length = 0.90 soleus muscle length, L0; length change = 0.25 L0; velocity = 1.5 L0/s; peak force = 180% maximal isometric tetanic tension (P0); time between contractions = 4 min; total duration of the injury protocol = 40 min). At the end of the injury protocol, the muscle was incubated in buffer for 1 h; every 15 min, an isometric twitch and tetanus were performed and lactate dehydrogenase (LDH) release was measured. Total muscle [Ca2+] was measured at the end of the incubation. 3. Change-point regression analysis indicates that at 0 min into the incubation, declines in P0, maximal rate of tension development (+dP/dt), maximal rate of relaxation (-dP/dt), and muscle stiffness (dP/dx) became significantly greater after eight eccentric contractions (p < or = 0.05). No relation was found between the number of eccentric contractions performed and the LDH activity at 0 min into the incubation, although after 60 min of incubation, LDH activity in the buffer was linearly related to eccentric contraction number (p = 0.01). There was no relationship between total muscle [Ca2+] and eccentric contraction number. These findings support the materials fatigue hypothesis of exercise-induced muscle injury. PMID:8229814

X-ray measurements of the strain and shape of dielectric/metallic wrap-gated InAs nanowires

NASA Astrophysics Data System (ADS)

Eymery, J.; Favre-Nicolin, V.; Fröberg, L.; Samuelson, L.

2009-03-01

Wrap-gate (111) InAs nanowires (NWs) were studied after HfO2 dielectric coating and Cr metallic deposition by a combination of grazing incidence x-ray techniques. In-plane and out-of-plane x-ray diffraction (crystal truncation rod analysis) allow determining the strain tensor. The longitudinal contraction, increasing with HfO2 and Cr deposition, is significantly larger than the radial dilatation. For the Cr coating, the contraction along the growth axis is quite large (-0.95%), and the longitudinal/radial deformation ratio is >10, which may play a role on the NW transport properties. Small angle x-ray scattering shows a smoothening of the initial hexagonal bare InAs NW shape and gives the respective core/shell thicknesses, which are compared to flat surface values.

Mechanisms of Microgravity Effect on Vascular Function

NASA Technical Reports Server (NTRS)

Purdy, Ralph E.

1995-01-01

The overall goal of the project is to characterize the effects of simulated microgravity on vascular function. Microgravity is simulated using the hindlimb unweighted (HU) rat, and the following vessels are removed from HU and paired control rats for in vitro analysis: abdominal aorta, carotid and femoral arteries, jugular and femoral veins. These vessels are cut into 3 mm long rings and mounted in tissue baths for the measurement of either isometric contraction, or relaxation of pre- contracted vessels. The isolated mesenteric vascular bed is perfused for the measurement of changes in perfusion pressure as an index of arteriolar constriction or dilation. This report presents, in addition to the statement of the overall goal of the project, a summary list of the specific hypotheses to be tested. These are followed by sections on results, conclusions, significance and plans for the next year.

Mechanisms behind intrauterine device-induced luteal persistence in mares.

PubMed

Rivera Del Alamo, M M; Reilas, T; Kindahl, H; Katila, T

2008-08-01

Intrauterine glass balls are used to prevent oestrous signs in sports mares, but the mechanism of action is unknown. It has been suggested that the glass ball can mimic an embryo or act via an induced chronic uterine inflammation and absent or continuous low-grade prostaglandin (PG) release. The purpose of this study was to induce prolonged luteal function in mares using a small intrauterine device (IUD) and to study the mechanisms behind prolonged IUD-induced luteal function. A uterine swab and a biopsy specimen were obtained in early oestrus. A water-filled plastic ball, diameter 20mm and weight 3.6g, was inserted into the uterus 2-4 days after ovulation; the control mares underwent similar cervical manipulation without ball insertion. The mares were examined three times per week until day 23 and twice weekly thereafter until they returned to oestrus (transrectal palpation, ultrasonography and progesterone determination). The location of the IUD was recorded and ultrasound scans were video-recorded to assess the frequency of uterine contractions. When the mare returned to oestrus, a uterine swab and biopsy specimen were obtained and the bacteriological, cytological and histological (inflammation and glandular dilation) results compared with the samples obtained before the IUD insertion. The PG F(2alpha) metabolite levels were measured in the plasma of four control mares and eight IUD mares on days 11-16. The IUD induced a prolonged luteal phase in 75% of the mares (9/12; IUD-P); the mean dioestrous length was 57.0 days. The three mares that did not respond to the IUD (IUD-N) showed a mean dioestrous length of 15.7 days and the 12 control mares 16.1 days. The inflammation and glandular dilation scores were not significantly different in pre- and post-manipulation biopsy specimens. Although locational changes of the IUD were observed, they occurred over very small distances and were mostly limited within the body-bifurcation area. The IUD-N and control mares showed increased uterine contractility 11-16 days post-ovulation, whereas the IUD-P mares did not. The control mares (n=4) and IUD-N mares (n=2) showed increased PG levels from day 14 post-ovulation, while the IUD-P mares (n=6) showed basal levels only. We concluded that the IUD did not cause continuous PG release and suggest that close contact of the IUD with the endometrium may prevent the endometrial cells from releasing PGF(2alpha).

The influence of muscle length on the fatigue-related reduction in joint range of motion of the human dorsiflexors.

PubMed

Cheng, Arthur J; Davidson, Andrew W; Rice, Charles L

2010-06-01

The fatigue-related reduction in joint range of motion (ROM) during dynamic contraction tasks may be related to muscle length-dependent alterations in torque and contractile kinetics, but this has not been systematically explored previously. Twelve young men performed a repetitive voluntary muscle shortening contraction task of the dorsiflexors at a contraction load of 30% of maximum voluntary isometric contraction (MVC) torque, until total 40 degrees ROM had decreased by 50% at task failure (POST) to 20 degrees ROM. At both a short (5 degrees dorsiflexion) and long muscle length (35 degrees plantar flexion joint angle relative to a 0 degrees neutral ankle joint position), voluntary activation, MVC torque, and evoked tibialis anterior contractile properties of a 52.8 Hz high-frequency isometric tetanus [peak evoked torque, maximum rate of torque development (MRTD), maximum rate of relaxation (MRR)] were evaluated at baseline (PRE), at POST, and up to 10 min of recovery. At POST, we measured similar fatigue-related reductions in torque (voluntary and evoked) and slowing of contractile kinetics (MRTD and MRR) at both the short and long muscle lengths. Thus, the fatigue-related reduction in ROM could not be explained by length-dependent fatigue. Although torque (voluntary and evoked) at both muscle lengths was depressed and remained blunted throughout the recovery period, this was not related to the rapid recovery of ROM at 0.5 min after task failure. The reduction in ROM, however, was strongly related to the reduction in joint angular velocity (R(2) = 0.80) during the fatiguing task, although additional factors cannot yet be overlooked.

Effect of a Flared Renal Stent on the Performance of Fenestrated Stent-Grafts at Rest and Exercise Conditions.

PubMed

Kandail, Harkamaljot; Hamady, Mohamad; Xu, Xiao Yun

2016-10-01

To quantify the hemodynamic impact of a flared renal stent on the performance of fenestrated stent-grafts (FSGs) by analyzing flow patterns and wall shear stress-derived parameters in flared and nonflared FSGs in different physiologic scenarios. Hypothetical models of FSGs were created with and without flaring of the proximal portion of the renal stent. Flared FSGs with different dilation angles and protrusion lengths were examined, as well as a nonplanar flared FSG to account for lumbar curvature. Laminar and pulsatile blood flow was simulated by numerically solving Navier-Stokes equations. A physiologically realistic flow rate waveform was prescribed at the inlet, while downstream vasculature was modeled using a lumped parameter 3-element windkessel model. No slip boundary conditions were imposed at the FSG walls, which were assumed to be rigid. While resting simulations were performed on all the FSGs, exercise simulations were also performed on a flared FSG to quantify the effect of flaring in different physiologic scenarios. For cycle-averaged inflow of 2.94 L/min (rest) and 4.63 L/min (exercise), 27% of blood flow was channeled into each renal branch at rest and 21% under exercise for all the flared FSGs examined. Although the renal flow waveform was not affected by flaring, flow within the flared FSGs was disturbed. This flow disturbance led to high endothelial cell activation potential (ECAP) values at the renal ostia for all the flared geometries. Reducing the dilation angle or protrusion length and exercise lowered the ECAP values for flared FSGs. Flaring of renal stents has a negligible effect on the time dependence of renal flow rate waveforms and can maintain sufficient renal perfusion at rest and exercise. Local flow patterns are, however, strongly dependent on renal flaring, which creates a local flow disturbance and may increase the thrombogenicity at the renal ostia. Smaller dilation angles, shorter protrusion lengths, and moderate lower limb exercise are likely to reduce the risk of thrombosis in flared geometries. © The Author(s) 2016.

Changes in passive tension of muscle in humans and animals after eccentric exercise

PubMed Central

Whitehead, N P; Weerakkody, N S; Gregory, J E; Morgan, D L; Proske, U

2001-01-01

This is a report of experiments on ankle extensor muscles of human subjects and a parallel series on the medial gastrocnemius of the anaesthetised cat, investigating the origin of the rise in passive tension after a period of eccentric exercise. Subjects exercised their triceps surae of one leg eccentrically by walking backwards on an inclined, forward-moving treadmill. Concentric exercise required walking forwards on a backwards-moving treadmill. For all subjects the other leg acted as a control. Immediately after both eccentric and concentric exercise there was a significant drop in peak active torque, but only after eccentric exercise was this accompanied by a shift in optimum angle for torque generation and a rise in passive torque. In the eccentrically exercised group some swelling and soreness developed but not until 24 h post-exercise. In the animal experiments the contracting muscle was stretched by 6 mm at 50 mm s−1 over a length range symmetrical about the optimum length for tension generation. Measurements of passive tension were made before and after the eccentric contractions, using small stretches to a range of muscle lengths, or with large stretches covering the full physiological range. After 150 eccentric contractions, passive tension was significantly elevated over most of the range of lengths. Measurements of work absorption during stretch-release cycles showed significant increases after the contractions. It is suggested that the rise in passive tension in both human and animal muscles after eccentric contractions is the result of development of injury contractures in damaged muscle fibres. PMID:11389215

Labial flap vaginoplasty with sacrospinous fixation

PubMed Central

Murthy, Chandrashekar; Ashok, Kiran; Kalal, Susheel Kumar

2010-01-01

We present a case of congenital absence of Vagina which was treated by reconstruction of the vagina using vascular labial flaps. Furthermore, we anchored the neo-vagina to the Sacro-spinous ligament on either side. The aim of the attachment to the sacro-spinous ligament is to provide a durable apical support and to give an immediate, good vaginal length. Various techniques have been described for the construction of Neo-vagina. Except for sigmoid vaginoplasty, most other procedures are associated with a significant risk of post-operative restenosis, for which prolonged dilatation is necessary. Attaching to the sacro-spinous ligament gives the vagina good depth and, to some extent, decreases the risk of re-stenosis. This technique is simpler, does not require sophisticated instruments or prolonged post operative dilatation and is particularly suitable for under-developed countries. PMID:24591942

Portable two-channel PPG cardiovascular sensor device

NASA Astrophysics Data System (ADS)

Spigulis, Janis; Erts, Renars; Ozols, Maris

2003-10-01

A portable sensor device for simultaneous detection and processing of skin-remitted optical signals from any two sites of the body has been developed and tested. The photoplethysmography (PPG) principle was applied to follow the dilatation and contraction of skin blood vessels during the cardiac cycle. The newly developed two-channel approach allows to estimate the vascular blood flow resistance by analysis of time shifts between the PPG pulses detected at different body sites. Potential of the sensor device for express-assessment of human cardio-vascular condition and for body fitness tests has been demonstrated.

Electrical Lumped Model Examination for Load Variation of Circulation System

NASA Astrophysics Data System (ADS)

Koya, Yoshiharu; Ito, Mitsuyo; Mizoshiri, Isao

Modeling and analysis of the circulation system enables the characteristic decision of circulation system in the body to be made. So, many models of circulation system have been proposed. But, they are complicated because the models include a lot of elements. Therefore, we proposed a complete circulation model as a lumped electrical circuit, which is comparatively simple. In this paper, we examine the effectiveness of the complete circulation model as a lumped electrical circuit. We use normal, angina pectoris, dilated cardiomyopathy and myocardial infarction for evaluation of the ventricular contraction function.

Measuring Contract Agency Performance with Administrative Data.

ERIC Educational Resources Information Center

Wulczyn, Fred; Orlebeke, Britany; Melamid, Elan

2000-01-01

Analyzed the relative performance of contract agencies providing out-of-home care by examining administrative data on the length of time it took children placed in out-of-home care to return to their families. Found that contract agency performance differs and that "agency effects" leave an independent imprint on a child's out-of-home…

Evaluating Seasonal Deformation in the Vicinity of Active Fault Structures in Central California Using GPS Data

NASA Astrophysics Data System (ADS)

Kraner, Meredith L.

Central California is a tectonically active region in the Western United States, which encompasses segments of both the San Andreas and Calaveras Faults and centers around the town of Parkfield, California. Recently, statistical studies of microseismicity suggest that earthquake rates in this region can vary seasonally. Also, studies using data from modern GPS networks have revealed that crustal deformation can be influenced by seasonal and nontectonic factors, such as hydrological, temperature, and atmospheric loads. Here we analyze eight-years (2008 - 2016) of GPS data and build on this idea by developing a robust seasonal model of dilatational and shear strain in Central California. Using an inversion, we model each GPS time series in our study region to derive seasonal horizontal displacements for each month of the year. These positions are detrended using robust MIDAS velocities, destepped using a Heavyside function, and demeaned to center the time series around zero. The stations we use are carefully chosen using a selection method which allows us to exclude stations located on unstable, heavily subsiding ground and include stations on sturdy bedrock. In building our seasonal strain model, we first filter these monthly seasonal horizontal displacements using a median-spatial filter technique called GPS Imaging to remove outliers and enhance the signal common to multiple stations. We then grid these seasonal horizontal filtered displacements and use them to model our dilatational and shear strain field for each month of the year. We setup our model such that a large portion of the strain in the region is accommodated on or near the San Andreas and Calaveras Faults. We test this setup using two sets of synthetic data and explore how varying the a priori faulting constraints of the on and off-fault standard deviations in the strain tensor affects the output of the model. We additionally extract strain time series for key regions along/near the San Andreas and Calaveras Faults. We find that the most prevalent seasonal strain signal exists in the main creeping section along the San Andreas Fault in Central California. This region, which runs from Parkfield to Bitterwater Valley, shows peaks in contraction (negative dilatation) during the wet period (February/March) and peaks in extension (positive dilatation) during the dry period (August/September). The north transitional creeping section along the San Andreas Fault and the Calaveras Fault displays general similarities with the main creeping section trend. In sharp contrast, seasonality is virtually undetected in the locked section of the San Andreas Fault south of the town of Cholame. Additionally, the southern transitional creeping section shows two distinct patterns. For the most part this region, between Parkfield and Cholame, shows peaks in contraction during the wet period (February/March) and peaks in extension during the dry period (August/September), similar to the main creeping section. However, the segment of the southern transitional creeping section surrounding the town of Cholame opposes this trend with peaks in extension during the wet period and peaks in contraction during the dry period. We postulate several causes for this seasonal signal, which we plan to explore further in future work.

A Study of Strong Stability of Distributed Systems. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Cataltepe, Tayfun

1989-01-01

The strong stability of distributed systems is studied and the problem of characterizing strongly stable semigroups of operators associated with distributed systems is addressed. Main emphasis is on contractive systems. Three different approaches to characterization of strongly stable contractive semigroups are developed. The first one is an operator theoretical approach. Using the theory of dilations, it is shown that every strongly stable contractive semigroup is related to the left shift semigroup on an L(exp 2) space. Then, a decomposition for the state space which identifies strongly stable and unstable states is introduced. Based on this decomposition, conditions for a contractive semigroup to be strongly stable are obtained. Finally, extensions of Lyapunov's equation for distributed parameter systems are investigated. Sufficient conditions for weak and strong stabilities of uniformly bounded semigroups are obtained by relaxing the equivalent norm condition on the right hand side of the Lyanupov equation. These characterizations are then applied to the problem of feedback stabilization. First, it is shown via the state space decomposition that under certain conditions a contractive system (A,B) can be strongly stabilized by the feedback -B(*). Then, application of the extensions of the Lyapunov equation results in sufficient conditions for weak, strong, and exponential stabilizations of contractive systems by the feedback -B(*). Finally, it is shown that for a contractive system, the first derivative of x with respect to time = Ax + Bu (where B is any linear bounded operator), there is a related linear quadratic regulator problem and a corresponding steady state Riccati equation which always has a bounded nonnegative solution.

Creating a Full-thickness Choroidal Incision: An Ex Vivo Analysis of Human and Porcine Tissue Contraction Dynamics

PubMed Central

LoBue, Stephen A.; Yamada, Norihiro; Choi, Moon Jeong; Olsen, Timothy W.

2017-01-01

Purpose We hypothesized that the elastic nature of the choroid leads to tissue contraction following a full-thickness, sharp incision. Furthermore, we sought to quantify, measure, and compare tissue contraction in ex vivo porcine globes and human globes of various ages using predetermined variables. Method A full-thickness, ex vivo choroidal incision was performed in either pig (n = 97) or human (n = 30) specimens. Variables included trephine diameter (1.5, 2.0, or 2.5 mm) versus a straight surgical blade, and temperature (1.7 °–4.4° vs. 36.6°F). Central centripetal and surround centrifugal tissue contractions were measured. Mean percentage tissue contraction was assessed as a ratio of trephine diameter to final tissue contraction measured immediately following each incision using a standardized device. Results For trephination in pig specimens, centripetal contraction ranged from 38% to 50% with a mean of 44%. Centrifugal contraction was approximately 15%. Human choroidal contraction was 39% and 15%, respectively, with a statistically significant inverse relationship to age (R2 = 0.35, P ≤ 0.01). Asymmetric contraction was noted when incisions were closer to choroidal attachment sites to the sclera, such as near vortex ampullae. Linear incisions resulted in contraction that correlated with incision length (R2 = 0.35, P ≤ 0.001). Conclusions A full-thickness choroidal incision results in significant tissue contraction. For circular incisions, the centripetal contraction approaches 50% of the original incision size. For linear incisions, the contraction corresponds directly with incision length. In human specimens, there is less contraction with advancing age. Translational Relevance Our findings have clinical relevance for choroidal biopsy, traumatic injury, and choroidal translocation surgery. PMID:29134136

The biophysics of asthmatic airway smooth muscle.

PubMed

Stephens, Newman L; Li, Weilong; Jiang, He; Unruh, H; Ma, Xuefei

2003-09-16

It is clear that significant advances have been made in the understanding of the physiology, biochemistry and molecular biology of airway smooth muscle (ASM) contraction and how the knowledge obtained from these approaches may be used to elucidate the pathogenesis of asthma. Not to belittle other theories of smooth muscle contraction extant in the field, perhaps the most outstanding development has been the formulation of plasticity theory. This may radically alter our understanding of smooth muscle contraction. Its message is that while shortening velocity and capacity are linear functions of length, active force is length independent. These changes are explained by the ability of thick filament protein to depolymerize at short lengths and to increase numbers of contractile units in series at lengths greater than optimal length or L(ref). Other advances are represented by the report that the major part of ASM shortening is complete within the initial first 20% of contraction time, that the nature and history of loading determine the extent of shortening and that these findings can be explained by the finding that the crossbridges are cycling four times faster than in the remaining time. Another unexpected finding is that late in the course of isotonic relaxation the muscle undergoes spontaneous activation which delays relaxation and smoothes it out; speculatively this could minimize turbulence of airflow. On the applied front evidence now shows the shortening ability of bronchial smooth muscle of human subjects of asthma is significantly increased. Measurements also indicate that increased smooth muscle myosin light chain kinase content, via increased actomyosin ATPase activity could be responsible for the changes in contractility.

Probing cooperative force generation in collective cancer invasion

NASA Astrophysics Data System (ADS)

Alobaidi, Amani A.; Xu, Yaopengxiao; Chen, Shaohua; Jiao, Yang; Sun, Bo

2017-08-01

Collective cellular dynamics in the three-dimensional extracellular matrix (ECM) plays a crucial role in many physiological processes such as cancer invasion. Both chemical and mechanical signaling support cell-cell communications on a variety of length scales, leading to collective migratory behaviors. Here we conduct experiments using 3D in vitro tumor models and develop a phenomenological model in order to probe the cooperativity of force generation in the collective invasion of breast cancer cells. In our model, cell-cell communication is characterized by a single parameter that quantifies the correlation length of cellular migration cycles. We devise a stochastic reconstruction method to generate realizations of cell colonies with specific contraction phase correlation functions and correlation length a. We find that as a increases, the characteristic size of regions containing cells with similar contraction phases grows. For small a values, the large fluctuations in individual cell contraction phases smooth out the temporal fluctuations in the time-dependent deformation field in the ECM. For large a values, the periodicity of an individual cell contraction cycle is clearly manifested in the temporal variation of the overall deformation field in the ECM. Through quantitative comparisons of the simulated and experimentally measured deformation fields, we find that the correlation length for collective force generation in the breast cancer diskoid in geometrically micropatterned ECM (DIGME) system is a≈ 25~μ \\text{m} , which is roughly twice the linear size of a single cell. One possible mechanism for this intermediate cell correlation length is the fiber-mediated stress propagation in the 3D ECM network in the DIGME system.

Experimental investigation of inlet-combustor isolators for a dual-mode scramjet at a Mach number of 4

NASA Technical Reports Server (NTRS)

Emami, Saied; Trexler, Carl A.; Auslender, Aaron H.; Weidner, John P.

1995-01-01

This report details experimentally derived operational characteristics of numerous two-dimensional planar inlet-combustor isolator configurations at a Mach number of 4. Variations in geometry included (1) inlet cowl length; (2) inlet cowl rotation angle; (3) isolator length; and (4) utilization of a rearward-facing isolator step. To obtain inlet-isolator maximum pressure-rise data relevant to ramjet-engine combustion operation, configurations were mechanically back pressured. Results demonstrated that the combined inlet-isolator maximum back-pressure capability increases as a function of isolator length and contraction ratio, and that the initiation of unstart is nearly independent of inlet cowl length, inlet cowl contraction ratio, and mass capture. Additionally, data are presented quantifying the initiation of inlet unstarts and the corresponding unstart pressure levels.

Muscle architecture and fibre characteristics of rat gastrocnemius and semimembranosus muscles during isometric contractions.

PubMed

Huijing, P A; van Lookeren Campagne, A A; Koper, J F

1989-01-01

Rat gastrocnemius medialis (GM) and semimembranosus (SM) muscles have a very different morphology. GM is a very pennate muscle, combining relatively short muscle fibre length with sizable fibre angles and long muscle and aponeurosis lengths. SM is a more parallel-fibred muscle, combining a relatively long fibre length with a small fibre angle and short aponeurosis length. The mechanisms of fibre shortening as well as angle increase are operational in GM as well as SM. However, as a consequence of isometric contraction, changes of fibre length and angle are greater for GM than for SM at any relative muscle length. These differences are particularly notable at short muscle lengths: at 80% of optimum muscle length, fibre length changes of approximately 30% are coupled to fibre angle changes of 15 degrees in GM, while for SM these changes are 4% and 0.6 degrees, respectively. A considerable difference was found for normalized active slack muscle length (GM approximately 80 and SM approximately 45%). This is explained by differences of degree of pennation as well as factors related to differences found for estimated fibre length-force characteristics. Estimated normalized active fibre slack length was considerably smaller for SM than for GM (approximately 40 and 60%, respectively). The most likely explanation of these findings are differences of distribution of optimum fibre lengths, possibly in combination with differences of myofilament lengths and/or fibre length distributions.

A two-phase solid/fluid model for dense granular flows including dilatancy effects

NASA Astrophysics Data System (ADS)

Mangeney, Anne; Bouchut, Francois; Fernandez-Nieto, Enrique; Koné, El-Hadj; Narbona-Reina, Gladys

2016-04-01

Describing grain/fluid interaction in debris flows models is still an open and challenging issue with key impact on hazard assessment [{Iverson et al.}, 2010]. We present here a two-phase two-thin-layer model for fluidized debris flows that takes into account dilatancy effects. It describes the velocity of both the solid and the fluid phases, the compression/dilatation of the granular media and its interaction with the pore fluid pressure [{Bouchut et al.}, 2016]. The model is derived from a 3D two-phase model proposed by {Jackson} [2000] based on the 4 equations of mass and momentum conservation within the two phases. This system has 5 unknowns: the solid and fluid velocities, the solid and fluid pressures and the solid volume fraction. As a result, an additional equation inside the mixture is necessary to close the system. Surprisingly, this issue is inadequately accounted for in the models that have been developed on the basis of Jackson's work [{Bouchut et al.}, 2015]. In particular, {Pitman and Le} [2005] replaced this closure simply by imposing an extra boundary condition at the surface of the flow. When making a shallow expansion, this condition can be considered as a closure condition. However, the corresponding model cannot account for a dissipative energy balance. We propose here an approach to correctly deal with the thermodynamics of Jackson's model by closing the mixture equations by a weak compressibility relation following {Roux and Radjai} [1998]. This relation implies that the occurrence of dilation or contraction of the granular material in the model depends on whether the solid volume fraction is respectively higher or lower than a critical value. When dilation occurs, the fluid is sucked into the granular material, the pore pressure decreases and the friction force on the granular phase increases. On the contrary, in the case of contraction, the fluid is expelled from the mixture, the pore pressure increases and the friction force diminishes. To account for this transfer of fluid into and out of the mixture, a two-layer model is proposed with a fluid layer on top of the two-phase mixture layer. Mass and momentum conservation are satisfied for the two phases, and mass and momentum are transferred between the two layers. A thin-layer approximation is used to derive average equations. Special attention is paid to the drag friction terms that are responsible for the transfer of momentum between the two phases and for the appearance of an excess pore pressure with respect to the hydrostatic pressure. We present several numerical tests of two-phase granular flows over sloping topography that are compared to the results of the model proposed by {Pitman and Le} [2005]. In particular, we quantify the role of the fluid and compression/dilatation processes on granular flow velocity field and runout distance. F. Bouchut, E.D. Fernandez-Nieto, A. Mangeney, G. Narbona-Reina, A two-phase shallow debris flow model with energy balance, {ESAIM: Math. Modelling Num. Anal.}, 49, 101-140 (2015). F. Bouchut, E. D. Fernandez-Nieto, A. Mangeney, G. Narbona-Reina, A two-phase two-layer model for fluidized granular flows with dilatancy effects, {J. Fluid Mech.}, submitted (2016). R.M. Iverson, M. Logan, R.G. LaHusen, M. Berti, The perfect debris flow? Aggregated results from 28 large-scale experiments, {J. Geophys. Res.}, 115, F03005 (2010). R. Jackson, The Dynamics of Fluidized Particles, {Cambridges Monographs on Mechanics} (2000). E.B. Pitman, L. Le, A two-fluid model for avalanche and debris flows, {Phil.Trans. R. Soc. A}, 363, 1573-1601 (2005). S. Roux, F. Radjai, Texture-dependent rigid plastic behaviour, {Proceedings: Physics of Dry Granular Media}, September 1997. (eds. H. J. Herrmann et al.). Kluwer. Cargèse, France, 305-311 (1998).

Importance of contraction history on muscle force of porcine urinary bladder smooth muscle.

PubMed

Menzel, Robin; Böl, Markus; Siebert, Tobias

2017-02-01

The purpose of this study was to provide a comprehensive dataset of porcine urinary bladder smooth muscle properties. Particularly, the history dependence of force production, namely force depression (FD) following shortening and force enhancement (FE) following stretch, was analysed. During active micturition, the circumference of the urinary bladder changes enormously. Thus, FD might be an important phenomenon during smooth muscle contraction. Electrically stimulated, intact urinary bladder strips from pigs (n = 10) were suspended in an aerated-filled organ bath, and different isometric, isotonic, and isokinetic contraction protocols were performed to determine the force-length and the force-velocity relation. FD and FE were assessed in concentric and eccentric contractions with different ramp lengths and ramp velocities. Bladder smooth muscles exhibit considerable amounts of FD and FE. The amount of FD increased significantly with ramp length, while FE did not change. However, FE and FD were independent of ramp velocity. The results imply that smooth muscle bladder strips exhibit similar muscle properties and history-dependent behaviour compared to striated muscles. The provided dataset of muscle properties is important for bladder modelling as well as for the analyses and interpretation of dynamic bladder filling and voiding.

Comparison of different digital elevation models and satellite imagery for lineament analysis: Implications for identification and spatial arrangement of fault zones in crystalline basement rocks of the southern Black Forest (Germany)

NASA Astrophysics Data System (ADS)

Meixner, J.; Grimmer, J. C.; Becker, A.; Schill, E.; Kohl, T.

2018-03-01

GIS-based remote sensing techniques and lineament mapping provide additional information on the spatial arrangement of faults and fractures in large areas with variable outcrop conditions. Due to inherent censoring and truncation bias mapping of lineaments is still a challenging task. In this study we show how statistical evaluations help to improve the reliability of lineament mappings by comparing two digital elevation models (ASTER, LIDAR) and satellite imagery data sets in the seismically active southern Black Forest. A statistical assessment of the orientation, average length, and the total length of mapped lineaments reveals an impact of the different resolutions of the data sets that allow to define maximum (censoring bias) and minimum (truncation bias) observable lineament length for each data set. The increase of the spatial resolution of the digital elevation model from 30 m × 30 m to 5 m × 5 m results in a decrease of total lineament length by about 40% whereby the average lineament lengths decrease by about 60%. Lineament length distributions of both data sets follow a power law distribution as documented elsewhere for fault and fracture systems. Predominant NE-, N-, NNW-, and NW-directions of the lineaments are observed in all data sets and correlate with well-known, mappable large-scale structures in the southern Black Forest. Therefore, mapped lineaments can be correlated with faults and hence display geological significance. Lineament density in the granite-dominated areas is apparently higher than in the gneiss-dominated areas. Application of a slip- and dilation tendency analysis on the fault pattern reveals largest reactivation potentials for WNW-ESE and N-S striking faults as strike-slip faults whereas normal faulting may occur along NW-striking faults within the ambient stress field. Remote sensing techniques in combination with highly resolved digital elevation models and a slip- and dilation tendency analysis thus can be used to quickly get first order results of the spatial arrangement of critically stressed faults in crystalline basement rocks.

48 CFR 215.404-71-3 - Contract type risk and working capital adjustment.

Code of Federal Regulations, 2011 CFR

2011-10-01

...) Description. The contract type risk factor focuses on the degree of cost risk accepted by the contractor under... extract from the DD 1547 is annotated to explain the process. Item Contractor risk factors Assigned value Base (item 20) Profit objective 24. CONTRACT type risk (1) (2) (3) Cost financed Length factor Interest...

Two new endemic species of Ameiva (Squamata: Teiidae) from the dry forest of northwestern Peru and additional information on Ameiva concolor Ruthven, 1924.

PubMed

Koch, Claudia; Venegas, Pablo J; Rödder, Dennis; Flecks, Morris; Böhme, Wolfgang

2013-12-04

We describe two new species of Ameiva Meyer, 1795 from the dry forest of the Northern Peruvian Andes. The new species Ameiva nodam sp. nov. and Ameiva aggerecusans sp. nov. share a divided frontal plate and are differentiated from each other and from their congeners based on genetic (12S and 16S rRNA genes) and morphological characteristics. A. nodam sp. nov. has dilated postbrachials, a maximum known snout-vent length of 101 mm, 10 longitudinal rows of ventral plates, 86-113 midbody granules, 25-35 lamellae under the fourth toe, and a color pattern with 5 longitudinal yellow stripes on the dorsum. Ameiva aggerecusans sp. nov. has not or only hardly dilated postbrachials, a maximum known snout-vent length of 99.3 mm, 10-12 longitudinal rows of ventral plates, 73-92 midbody granules, 31-39 lamellae under the fourth toe, and the females and juveniles of the species normally exhibit a cream-colored vertebral stripe on a dark dorsum ground color. We provide information on the intraspecific variation and distribution of A. concolor. Furthermore, we provide information on the environmental niches of the taxa and test for niche conservatism. 

Histologic definition of gastro-esophageal reflux disease.

PubMed

Chandrasoma, Parakrama T

2013-07-01

To review recent data supporting the development of new histology-based definitions of gastro-esophageal reflux disease (GERD). Three precisely definable columnar epithelial types--cardiac, oxyntocardiac and intestinal--may be interposed between esophageal squamous epithelium and gastric oxyntic (acid secreting) mucosa. This enables definition of a new histologic concept: the squamo-oxyntic gap. The squamo-oxyntic gap is zero or very small in autopsies performed on patients without evidence of GERD. The gap progressively increases in length with the severity of GERD, indicating that the squamo-oxyntic gap is a marker for chronic GERD. The distal part of the gap lines gastric-type rugal folds and, therefore, is distal to the present endoscopic definition of the gastro-esophageal junction. I contend that this distal gap segment (which has esophageal submucosal glands) is actually the dilated distal esophagus; this is the pathologic correlate of destruction of the abdominal segment of the lower esophageal sphincter. The dilated distal esophagus is mistaken for 'gastric cardia' by present endoscopic definitions. I believe that these data support the adoption of novel histologic definitions of GERD as follows: the presence of any squamo-oxyntic gap defines GERD; the length of the gap is a measure of severity of chronic GERD; and the presence of intestinal metaplasia in the gap defines Barrett esophagus and cancer risk.

SarcOptiM for ImageJ: high-frequency online sarcomere length computing on stimulated cardiomyocytes.

PubMed

Pasqualin, Côme; Gannier, François; Yu, Angèle; Malécot, Claire O; Bredeloux, Pierre; Maupoil, Véronique

2016-08-01

Accurate measurement of cardiomyocyte contraction is a critical issue for scientists working on cardiac physiology and physiopathology of diseases implying contraction impairment. Cardiomyocytes contraction can be quantified by measuring sarcomere length, but few tools are available for this, and none is freely distributed. We developed a plug-in (SarcOptiM) for the ImageJ/Fiji image analysis platform developed by the National Institutes of Health. SarcOptiM computes sarcomere length via fast Fourier transform analysis of video frames captured or displayed in ImageJ and thus is not tied to a dedicated video camera. It can work in real time or offline, the latter overcoming rotating motion or displacement-related artifacts. SarcOptiM includes a simulator and video generator of cardiomyocyte contraction. Acquisition parameters, such as pixel size and camera frame rate, were tested with both experimental recordings of rat ventricular cardiomyocytes and synthetic videos. It is freely distributed, and its source code is available. It works under Windows, Mac, or Linux operating systems. The camera speed is the limiting factor, since the algorithm can compute online sarcomere shortening at frame rates >10 kHz. In conclusion, SarcOptiM is a free and validated user-friendly tool for studying cardiomyocyte contraction in all species, including human. Copyright © 2016 the American Physiological Society.

Physiology of male sexual function.

PubMed

deGroat, W C; Booth, A M

1980-02-01

The male sexual response cycle consists of excitement, plateau, orgasm, and resolution. The initial event, penile erection, is produced by arteriolar dilatation and increased blood flow to the erectile tissue of the penis. Erection is a reflex response initiated by visual, olfactory, or imaginative stimuli impinging upon supraspinal centers or by genital stimulation that in turn activates spinal reflex mechanisms. Sacral parasympathetic and thoracolumbar sympathetic nerves provide the efferent vasodilator input to the penis. Parasympathetic nerves also stimulate secretion from the seminal vesicles and prostate and Cowper's glands during the plateau phase. The orgasmic phase is characterized by seminal emission and ejaculation and the accompanying sensations. Emission of semen into the urethra depends on sympathetic nerves that elicit contractions of smooth muscles in the vas deferens, seminal vesicles, and prostate. Rhythmic contractions of striated muscle (bulbocavernosus and ischiocavernosus) generated by efferent pathways in the pudendal nerve eject semen from the urethra.

Human muscle fascicle behavior in agonist and antagonist isometric contractions.

PubMed

Simoneau, Emilie M; Longo, Stefano; Seynnes, Olivier R; Narici, Marco V

2012-01-01

The aim of this study was to compare, at a given level of electromyographic (EMG) activity, the behavior of dorsiflexor and plantarflexor muscles as assessed via their architecture (pennation angle and fiber length) during agonist or antagonist isometric contractions. Real-time ultrasonography and EMG activity of gastrocnemius medialis (GM) and tibialis anterior (TA) muscles were obtained while young males performed ramp isometric contractions in dorsi- and plantarflexion. For both muscles, at a similar level of EMG activity, fiber length was longer, and pennation angle was smaller, during antagonist than during agonist contractions. These results indicate that, at similar levels of EMG activity, GM and TA muscles elicit a higher mechanical output while acting as an antagonist. These findings have important implications for muscle function testing. They show that estimation of antagonistic force using the common method based on the EMG/net torque relationship yields underestimated values. Copyright © 2011 Wiley Periodicals, Inc.

The origins of length contraction: I. The FitzGerald-Lorentz deformation hypothesis

NASA Astrophysics Data System (ADS)

Brown, Harvey R.

2001-10-01

"Can there be some point in the theory of Mr. Michelson's experiment which has yet been overlooked?" H. A. Lorentz, letter to Lord Rayleigh, August 1892. One of the widespread confusions concerning the history of the 1887 Michelson-Morley experiment has to do with the initial explanation of this celebrated null result due independently to FitzGerald and Lorentz. In neither case was a strict, longitudinal length contraction hypothesis invoked, as is commonly supposed. Lorentz postulated, particularly in 1895, any one of a certain family of possible deformation effects for rigid bodies in motion, including purely transverse alteration, and expansion as well as contraction; FitzGerald may well have had the same family in mind. A careful analysis of the Michelson-Morley experiment (which reveals a number of serious inadequacies in many textbook treatments) indeed shows that strict contraction is not required.

New endoscopic indicator of esophageal achalasia: "pinstripe pattern".

PubMed

Minami, Hitomi; Isomoto, Hajime; Miuma, Satoshi; Kobayashi, Yasutoshi; Yamaguchi, Naoyuki; Urabe, Shigetoshi; Matsushima, Kayoko; Akazawa, Yuko; Ohnita, Ken; Takeshima, Fuminao; Inoue, Haruhiro; Nakao, Kazuhiko

2015-01-01

Endoscopic diagnosis of esophageal achalasia lacking typical endoscopic features can be extremely difficult. The aim of this study was to identify simple and reliable early indicator of esophageal achalasia. This single-center retrospective study included 56 cases of esophageal achalasia without previous treatment. As a control, 60 non-achalasia subjects including reflux esophagitis and superficial esophageal cancer were also included in this study. Endoscopic findings were evaluated according to Descriptive Rules for Achalasia of the Esophagus as follows: (1) esophageal dilatation, (2) abnormal retention of liquid and/or food, (3) whitish change of the mucosal surface, (4) functional stenosis of the esophago-gastric junction, and (5) abnormal contraction. Additionally, the presence of the longitudinal superficial wrinkles of esophageal mucosa, "pinstripe pattern (PSP)" was evaluated endoscopically. Then, inter-observer diagnostic agreement was assessed for each finding. The prevalence rates of the above-mentioned findings (1-5) were 41.1%, 41.1%, 16.1%, 94.6%, and 43.9%, respectively. PSP was observed in 60.7% of achalasia, while none of the control showed positivity for PSP. PSP was observed in 26 (62.5%) of 35 cases with shorter history < 10 years, which usually lacks typical findings such as severe esophageal dilation and tortuosity. Inter-observer agreement level was substantial for food/liquid remnant (k = 0.6861) and PSP (k = 0.6098), and was fair for abnormal contraction and white change. The accuracy, sensitivity, and specificity for achalasia were 83.8%, 64.7%, and 100%, respectively. "Pinstripe pattern" could be a reliable indicator for early discrimination of primary esophageal achalasia.

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.

Effects of gap junction inhibition on contraction waves in the murine small intestine in relation to coupled oscillator theory.

PubMed

Parsons, Sean P; Huizinga, Jan D

2015-02-15

Waves of contraction in the small intestine correlate with slow waves generated by the myenteric network of interstitial cells of Cajal. Coupled oscillator theory has been used to explain steplike gradients in the frequency (frequency plateaux) of contraction waves along the length of the small intestine. Inhibition of gap junction coupling between oscillators should lead to predictable effects on these plateaux and the wave dislocation (wave drop) phenomena associated with their boundaries. It is these predictions that we wished to test. We used a novel multicamera diameter-mapping system to measure contraction along 25- to 30-cm lengths of murine small intestine. There were typically two to three plateaux per length of intestine. Dislocations could be limited to the wavefronts immediately about the terminated wave, giving the appearance of a three-pronged fork, i.e., a fork dislocation; additionally, localized decreases in velocity developed across a number of wavefronts, ending with the terminated wave, which could appear as a fork, i.e., slip dislocations. The gap junction inhibitor carbenoxolone increased the number of plateaux and dislocations and decreased contraction wave velocity. In some cases, the usual frequency gradient was reversed, with a plateau at a higher frequency than its proximal neighbor; thus fork dislocations were inverted, and the direction of propagation was reversed. Heptanol had no effect on the frequency or velocity of contractions but did reduce their amplitude. To understand intestinal motor patterns, the pacemaker network of the interstitial cells of Cajal is best evaluated as a system of coupled oscillators. Copyright © 2015 the American Physiological Society.

Identifying DNA methylation in a nanochannel

NASA Astrophysics Data System (ADS)

Sun, Xiaoyin; Yasui, Takao; Yanagida, Takeshi; Kaji, Noritada; Rahong, Sakon; Kanai, Masaki; Nagashima, Kazuki; Kawai, Tomoji; Baba, Yoshinobu

2016-01-01

DNA methylation is a stable epigenetic modification, which is well known to be involved in gene expression regulation. In general, however, analyzing DNA methylation requires rather time consuming processes (24-96 h) via DNA replication and protein modification. Here we demonstrate a methodology to analyze DNA methylation at a single DNA molecule level without any protein modifications by measuring the contracted length and relaxation time of DNA within a nanochannel. Our methodology is based on the fact that methylation makes DNA molecules stiffer, resulting in a longer contracted length and a longer relaxation time (a slower contraction rate). The present methodology offers a promising way to identify DNA methylation without any protein modification at a single DNA molecule level within 2 h.

Pricing structures in US coal supply contracts

NASA Astrophysics Data System (ADS)

Kacker, Kanishka

The subject of my dissertation is the study of coal procurement by electric utilities in the US over 2 decades, from 1979 to 2000. Energy markets are typically characterized by severe contracting problems. Buyers and sellers therefore employ various instruments, such as contract length or complex pricing arrangements, to restrict these problems. Relationship specific investment, wherein buyers make investments specific to their suppliers, has been advanced as a prominent explanation for contractual length. Investment decisions are however endogenous in length or pricing, making causal identification of the role of investment specificity difficult. In my first chapter, I attempt a resolution. I use the 1990 Clean Air Act Amendment as an exogenous shifter of the extent of relationship specific investment. A key feature of the Amendment's design helps me define a difference-in-difference model arguably free of the endogeneity issues discussed above. I find that the plants forced into switching - Phase I plants located in the US Midwest - are more likely to choose fixed price contracts than those that were not. Further they also write contracts of shorter terms, with the reduction being approximately 30%. Considerably little is known about the performance implications of contractual choices. These form the basis for Chapter 2. Here I find prices to be lower, by between 5% to 20% of the total transaction price, but the probability of renegotiation higher, under fixed price contracts than under escalator or cost-plus contracts. Contract choices appear consistent with a trade-off between establishing incentives ex-ante and lowering negotiation costs ex-post, with relationship specific investments in particular making such a trade-off compelling. Chapter 3 considers the regulatory environment these utilities were subject to. Both incentive based regulation as well as the restructuring of electricity generation are smaller in comparison to relationship specific investment in terms of their effects on contractual decisions. Consequently, when evaluating the effect of these reforms, ignoring the contractual structure of fuel procurement - and therefore investment specificity - leads to large and significant biases in their impacts.

Vascular reactivity in arterioles from normal and alloxan-diabetic mice: studies on single perfused islets.

PubMed

Lai, En Yin; Jansson, Leif; Patzak, Andreas; Persson, A Erik G

2007-01-01

Pancreatic islets possess an autonomous mechanism of blood flow regulation, independent of that of the exocrine pancreas. To study islet vascular regulation without confounding effects of the exocrine blood vessels, we have developed a technique enabling us to isolate single pancreatic islets and then to perfuse them using their endogenous vasculature for distribution of the medium. This made it possible to directly study the vascular reactivity of islet arterioles to different substances. We confirmed that control of islet blood flow is mainly located at the precapillary level. As expected, administration of angiotensin II and l-nitro-arginine methyl ester contracted islet arterioles, whereas nitric oxide and adenosine dilated them. d-glucose, the main insulin secretagogue, had a selective dilating effect on smooth muscle in islet arterioles but not in glomerular afferent arterioles. The response to glucose was amplified in islet arterioles from diabetic animals, indicating enhanced islet blood perfusion in diabetes. This newly developed technique for perfusing isolated pancreatic islets will provide new insights into islet perfusion control and its possible contributions to the pathogenesis of type 2 diabetes.

Effects of myosin variants on interacting-heads motif explain distinct hypertrophic and dilated cardiomyopathy phenotypes

PubMed Central

Alamo, Lorenzo; Ware, James S; Pinto, Antonio; Gillilan, Richard E; Seidman, Jonathan G; Seidman, Christine E; Padrón, Raúl

2017-01-01

Cardiac β-myosin variants cause hypertrophic (HCM) or dilated (DCM) cardiomyopathy by disrupting sarcomere contraction and relaxation. The locations of variants on isolated myosin head structures predict contractility effects but not the prominent relaxation and energetic deficits that characterize HCM. During relaxation, pairs of myosins form interacting-heads motif (IHM) structures that with other sarcomere proteins establish an energy-saving, super-relaxed (SRX) state. Using a human β-cardiac myosin IHM quasi-atomic model, we defined interactions sites between adjacent myosin heads and associated protein partners, and then analyzed rare variants from 6112 HCM and 1315 DCM patients and 33,370 ExAC controls. HCM variants, 72% that changed electrostatic charges, disproportionately altered IHM interaction residues (expected 23%; HCM 54%, p=2.6×10−19; DCM 26%, p=0.66; controls 20%, p=0.23). HCM variant locations predict impaired IHM formation and stability, and attenuation of the SRX state - accounting for altered contractility, reduced diastolic relaxation, and increased energy consumption, that fully characterizes HCM pathogenesis. DOI: http://dx.doi.org/10.7554/eLife.24634.001 PMID:28606303

An exploratory investigation of echocardiographic parameters and the effects of posture on cardiac structure and function in the Livingstone's fruit bat (Pteropus livingstonii).

PubMed

Drane, Aimee L; Shave, Robert; Routh, Andrew; Barbon, Alberto

2018-01-01

There is growing evidence that dilated cardiomyopathy may be a major cause of death in captive Livingstone's fruit bats (Pteropus livingstonii). Therefore, the primary aim of this prospective, exploratory study was to examine whether a systematic cardiac ultrasound protocol is feasible in this critically endangered species and to report basic measures of cardiac structure and function from a cohort of apparently healthy bats. A secondary aim was to test the effect posture (dorsal recumbency vs. roosting) has upon cardiac function in this species. Transthoracic echocardiograms, including 2D, Doppler, and tissue Doppler measures of cardiac structure and function were completed as part of routine health examinations for bats at a single center (n = 19). Bats were then grouped by age and disease status and the mean and range data reported for each group. In healthy adult bats, with the exception of a reduction in heart rate (P ≤ 0.05), right atrial systolic area (P ≤ 0.05), and right ventricular velocity during atrial contraction, there were no significant changes in cardiac structure or function in response to the roosting position. However, in the bats presenting with dilated cardiomyopathy the current data suggest that left ventricular ejection fraction is improved while roosting. Further work is required to confirm our initial findings, generate diagnostic reference intervals, and explore the causes of dilated cardiomyopathy in this species. © 2017 American College of Veterinary Radiology.

High-resolution manometry classifications for idiopathic achalasia in patients with Chagas' disease esophagopathy.

PubMed

Vicentine, Fernando P P; Herbella, Fernando A M; Allaix, Marco E; Silva, Luciana C; Patti, Marco G

2014-02-01

Idiopathic achalasia (IA) and Chagas' disease esophagopathy (CDE) share several similarities. The comparison between IA and CDE is important to evaluate whether treatment options and their results can be accepted universally. High-resolution manometry (HRM) has proved a better diagnostic tool compared to conventional manometry. This study aims to evaluate HRM classifications for idiopathic achalasia in patients with CDE. We studied 98 patients: 52 patients with CDE (52 % females, mean age, 57 ± 14 years) and 46 patients with IA (54 % females; mean age 48 ± 19 years). All patients underwent a HRM and barium esophagogram. The Chicago classification was distributed in IA as Chicago I, 35 %; Chicago II, 63 %; and Chicago III, 2 %, and in CDE as Chicago I, 52 %; Chicago II, 48 %; and Chicago III, 0 % (p = 0.1, 0.1, and 0.5, respectively). All patients had the classic Rochester type. CDE patients had more pronounced degrees of esophageal dilatation (p < 0.002). The degree of esophageal dilatation did not correlate with Chicago classification (p = 0.08). In nine (9 %) patients, the HRM pattern changed during the test from Chicago I to II. Our results show that (a) HRM classifications for IA can be applied in patients with CDE and (b) HRM classifications did not correlate with the degree of esophageal dilatation. HRM classifications may reflect esophageal repletion and pressurization instead of muscular contraction. The correlation between manometric findings and treatment outcomes for CDE needs to be answered in the near future.

Rigor mortis at the myocardium investigated by post-mortem magnetic resonance imaging.

PubMed

Bonzon, Jérôme; Schön, Corinna A; Schwendener, Nicole; Zech, Wolf-Dieter; Kara, Levent; Persson, Anders; Jackowski, Christian

2015-12-01

Post-mortem cardiac MR exams present with different contraction appearances of the left ventricle in cardiac short axis images. It was hypothesized that the grade of post-mortem contraction may be related to the post-mortem interval (PMI) or cause of death and a phenomenon caused by internal rigor mortis that may give further insights in the circumstances of death. The cardiac contraction grade was investigated in 71 post-mortem cardiac MR exams (mean age at death 52 y, range 12-89 y; 48 males, 23 females). In cardiac short axis images the left ventricular lumen volume as well as the left ventricular myocardial volume were assessed by manual segmentation. The quotient of both (LVQ) represents the grade of myocardial contraction. LVQ was correlated to the PMI, sex, age, cardiac weight, body mass and height, cause of death and pericardial tamponade when present. In cardiac causes of death a separate correlation was investigated for acute myocardial infarction cases and arrhythmic deaths. LVQ values ranged from 1.99 (maximum dilatation) to 42.91 (maximum contraction) with a mean of 15.13. LVQ decreased slightly with increasing PMI, however without significant correlation. Pericardial tamponade positively correlated with higher LVQ values. Variables such as sex, age, body mass and height, cardiac weight and cause of death did not correlate with LVQ values. There was no difference in LVQ values for myocardial infarction without tamponade and arrhythmic deaths. Based on the observation in our investigated cases, the phenomenon of post-mortem myocardial contraction cannot be explained by the influence of the investigated variables, except for pericardial tamponade cases. Further research addressing post-mortem myocardial contraction has to focus on other, less obvious factors, which may influence the early post-mortem phase too. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Advancing age produces sex differences in vasomotor kinetics during and after skeletal muscle contraction.

PubMed

Bearden, Shawn E

2007-09-01

Little is known of the vasomotor responses of skeletal muscle arterioles during and following muscle contraction. We hypothesized that aging leads to impaired arteriolar responses to muscle contraction and recovery. Nitric oxide (NO) availability, which is age dependent, has been implicated in components of these kinetics. Therefore, we also hypothesized that changes in the kinetics of vascular responses are associated with the NO pathway. Groups were young (3 mo), old (24 mo), endothelial NO synthase knockout (eNOS-/-), and N(G)-nitro-L-arginine (L-NA)-treated male and female C57BL/6 mice. The kinetics of vasodilation during and following 1 min of contractions of the gluteus maximus muscle were recorded in second-order (regional distribution) and third-order (local control) arterioles. Baseline, peak (during contraction), and maximal diameters (pharmacological) were not affected by age or sex. The kinetics of dilation and recovery were not different between males and females at the young age. There was a significant slowing of vasodilation at the onset of contractions (approximately 2-fold; P < 0.05) and a significant speeding of recovery ( approximately 5-fold; P < 0.05) in old males vs. old females and vs. young eNOS-/-, and L-NA did not affect the kinetics at the onset of muscle contraction. eNOS-/- mimicked the rapid recovery of old males in second-order arterioles; acute NO production (L-NA) explained approximately 50% of this effect. These data demonstrate fundamental age-related differences between the sexes in the dynamic function of skeletal muscle arterioles. Understanding how youthful function persists in females but not males may provide therapeutic insight into clinical interventions to maintain dynamic microvascular control of nutrient supply with age.

Change in muscle fascicle length influences the recruitment and discharge rate of motor units during isometric contractions.

PubMed

Pasquet, Benjamin; Carpentier, Alain; Duchateau, Jacques

2005-11-01

This study examines the effect of fascicle length change on motor-unit recruitment and discharge rate in the human tibialis anterior (TA) during isometric contractions of various intensities. The torque produced during dorsiflexion and the surface and intramuscular electromyograms (EMGs) from the TA were recorded in eight subjects. The behavior of the same motor unit (n = 59) was compared at two ankle joint angles (+10 and -10 degrees around the ankle neutral position). Muscle fascicle length of the TA was measured noninvasively using ultrasonography recordings. When the ankle angle was moved from 10 degrees plantarflexion to 10 degrees dorsiflexion, the torque produced during maximal voluntary contraction (MVC) was significantly reduced [35.2 +/- 3.3 vs. 44.3 +/- 4.2 (SD) Nm; P < 0.001] and the average surface EMG increased (0.47 +/- 0.08 vs. 0.43 +/- 0.06 mV; P < 0.05). At reduced ankle joint angle, muscle fascicle length declined by 12.7% (P < 0.01) at rest and by 18.9% (P < 0.001) during MVC. Motor units were activated at a lower recruitment threshold for short compared with long muscle fascicle length, either when expressed in absolute values (2.1 +/- 2.5 vs. 3.6 +/- 3.7 Nm; P < 0.001) or relative to their respective MVC (5.2 +/- 6.1 vs. 8.8 +/- 9.0%). Higher discharge rate and additional motor-unit recruitment were observed at a given absolute or relative torque when muscle fascicles were shortened. However, the data indicate that increased rate coding was mainly present at low torque level (<10% MVC), when the muscle-tendon complex was compliant, whereas recruitment of additional motor units played a dominant role at higher torque level and decreased compliance (10-35% MVC). Taken together, the results suggest that the central command is modulated by the afferent proprioceptive information during submaximal contractions performed at different muscle fascicle lengths.

A new methodological approach to assess cardiac work by pressure-volume and stress-length relations in patients with aortic valve stenosis and dilated cardiomyopathy.

PubMed

Alter, P; Rupp, H; Rominger, M B; Klose, K J; Maisch, B

2008-01-01

In experimental animals, cardiac work is derived from pressure-volume area and analyzed further using stress-length relations. Lack of methods for determining accurately myocardial mass has until now prevented the use of stress-length relations in patients. We hypothesized, therefore, that not only pressure-volume loops but also stress-length diagrams can be derived from cardiac volume and cardiac mass as assessed by cardiac magnetic resonance imaging (CMR) and invasively measured pressure. Left ventricular (LV) volume and myocardial mass were assessed in seven patients with aortic valve stenosis (AS), eight with dilated cardiomyopathy (DCM), and eight controls using electrocardiogram (ECG)-gated CMR. LV pressure was measured invasively. Pressure-volume curves were calculated based on ECG triggering. Stroke work was assessed as area within the pressure-volume loop. LV wall stress was calculated using a thick-wall sphere model. Similarly, stress-length loops were calculated to quantify stress-length-based work. Taking the LV geometry into account, the normalization with regard to ventricular circumference resulted in "myocardial work." Patients with AS (valve area 0.73+/-0.18 cm(2)) exhibited an increased LV myocardial mass when compared with controls (P<0.05). LV wall stress was increased in DCM but not in AS. Stroke work of AS was unchanged when compared with controls (0.539+/-0.272 vs 0.621+/-0.138 Nm, not significant), whereas DCM exhibited a significant depression (0.367+/-0.157 Nm, P<0.05). Myocardial work was significantly reduced in both AS and DCM when compared with controls (129.8+/-69.6, 200.6+/-80.1, 332.2+/-89.6 Nm/m(2), P<0.05), also after normalization (7.40+/-5.07, 6.27+/-3.20, 14.6+/-4.07 Nm/m(2), P<0.001). It is feasible to obtain LV pressure-volume and stress-length diagrams in patients based on the present novel methodological approach of using CMR and invasive pressure measurement. Myocardial work was reduced in patients with DCM and noteworthy also in AS, while stroke work was reduced in DCM only. Most likely, deterioration of myocardial work is crucial for the prognosis. It is suggested to include these basic physiological procedures in the clinical assessment of the pump function of the heart.

Non-peristaltic patterns of motor activity in the guinea-pig proximal colon.

PubMed

Hennig, G W; Gregory, S; Brookes, S J H; Costa, M

2010-06-01

The guinea-pig proximal colon contains semi-solid feces which are propelled by intermittent neural peristaltic waves to the distal colon, where solid pellets are formed. Between propulsive periods, complex motor patterns underlie fluid re-absorption and mixing of contents. Spatio-temporal analysis of video recordings were used to investigate neural and myogenic patterns of non-peristaltic motor activity. At low distension (6 cmH(2)O), two major motor patterns were seen. Narrow rings of constriction (abrupt contractions) occurred at 19 cpm. These previously undescribed contractions occurred, almost simultaneously, at many points along the preparation, with a calculated propagation velocity of 110 mm s(-1). They were abolished by hexamethonium and by tetrodotoxin, indicating they were neurally mediated. Inhibition of nitric oxide synthase resulted in increased frequency of 'abrupt contractions' suggesting ongoing inhibitory modulation by endogenous nitric oxide. After tetrodotoxin, another distinct motor pattern was revealed; 'ripples'(1) consisted of shallow rings of contraction, occurring at 18 cpm and propagating at 2.7-2.9 mm s(-1) orally or aborally from multiple initiation sites. The frequency of 'ripples' increased as intraluminal pressure was raised, becoming very irregular at high distensions. L-type calcium channel blockers and openers affected the amplitude of 'ripples'. No frequency gradient of 'ripples' along the proximal colon was detected. This absence explains the multiple initiation sites which often shifted over time, and the oral and aboral propagation of 'ripples'. The interaction of myogenic 'ripples' with neurogenic 'abrupt contractions' generates localized alternating rings of contractions and dilatation, well suited to effective mixing of contents.

Stenting for curved lesions using a novel curved balloon: Preliminary experimental study.

PubMed

Tomita, Hideshi; Higaki, Takashi; Kobayashi, Toshiki; Fujii, Takanari; Fujimoto, Kazuto

2015-08-01

Stenting may be a compelling approach to dilating curved lesions in congenital heart diseases. However, balloon-expandable stents, which are commonly used for congenital heart diseases, are usually deployed in a straight orientation. In this study, we evaluated the effect of stenting with a novel curved balloon considered to provide better conformability to the curved-angled lesion. In vitro experiments: A Palmaz Genesis(®) stent (Johnson & Johnson, Cordis Co, Bridgewater, NJ, USA) mounted on the Goku(®) curve (Tokai Medical Co. Nagoya, Japan) was dilated in vitro to observe directly the behavior of the stent and balloon assembly during expansion. Animal experiment: A short Express(®) Vascular SD (Boston Scientific Co, Marlborough, MA, USA) stent and a long Express(®) Vascular LD stent (Boston Scientific) mounted on the curved balloon were deployed in the curved vessel of a pig to observe the effect of stenting in vivo. In vitro experiments: Although the stent was dilated in a curved fashion, stent and balloon assembly also rotated conjointly during expansion of its curved portion. In the primary stenting of the short stent, the stent was dilated with rotation of the curved portion. The excised stent conformed to the curved vessel. As the long stent could not be negotiated across the mid-portion with the balloon in expansion when it started curving, the mid-portion of the stent failed to expand fully. Furthermore, the balloon, which became entangled with the stent strut, could not be retrieved even after complete deflation. This novel curved balloon catheter might be used for implantation of the short stent in a curved lesion; however, it should not be used for primary stenting of the long stent. Post-dilation to conform the stent to the angled vessel would be safer than primary stenting irrespective of stent length. Copyright © 2014 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

Sigmoid colon vaginoplasty in children.

PubMed

Ekinci, S; Karnak, I; Ciftci, A O; Senocak, M E; Tanyel, F C; Büyükpamukçu, N

2006-06-01

Vaginal construction is necessary for the patients with aplasia of Mullerian ducts, testicular feminisation and androgen insensitivity syndromes. Many methods of vaginal construction have been described. We report here the outcomes of six adolescent patients who underwent sigmoid colon vaginoplasty with special emphasis on the surgical technique and outcomes. Between 1990 and 2003, six patients underwent sigmoid vaginoplasty after a diagnosis of 5alpha-reductase deficiency (n = 3), testicular feminisation (n = 2) or vaginal atresia (n = 1). The mean age was 16 years (13 to 18). Wide spectrum antibiotics and whole-gut preparation were used in all cases. A 15-20 cm segment of sigmoid colon was pulled through the retrovesical tunnel. The proximal end was closed in two layers in patients with 5alpha-reductase deficiency and with testicular feminisation. A distal anastomosis was carried out to the opening made on the vaginal plate (5alpha-reductase deficiency) or on the tip of the shallow rudimentary vagina (testicular feminisation). The sigmoid segment was interposed between the blind end of the atretic vagina and the perineum in the patient with vaginal atresia. Patients were instructed to perform daily vaginal irrigation. The neovagina was examined and calibrated under anaesthesia. No routine vaginal dilatation was recommended. All but one patient had an uneventful postoperative period and were discharged within 7-8 days. All patients had an excellent cosmetic result with an appropriate vaginal length. One of the patients experienced late stenosis of the introitus which responded to dilatations. Mucus discharge was not a significant problem. The patient with vaginal atresia (Bardet-Biedl syndrome) experienced deep vein thrombosis, renal failure and sepsis, resulting in death. Sigmoid colon vaginoplasty is a special procedure which appears appropriate for the construction of a new vagina in children. A sigmoid colon neovagina meets all necessary criteria after a vaginoplasty. It provides an adequate diameter and length, and produces less scar tissue in the perineum. It is self-moistening, easily adaptable to the uterus, cervix and rudimentary atretic vaginal segments and does not require routine dilatation. Mild stenosis of the introitus can be treated by dilatations and revision can be easily performed in severely stenotic cases. On the other hand, the patient may face morbidity after laparotomy and other serious complications may occur due to accompanying diseases.

Electronic doping of transition metal oxide perovskites

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

Cammarata, Antonio, E-mail: cammaant@fel.cvut.cz; Rondinelli, James M.

2016-05-23

CaFeO{sub 3} is a prototypical negative charge transfer oxide that undergoes electronic metal-insulator transition concomitant with a dilation and contraction of nearly rigid octahedra. Altering the charge neutrality of the bulk system destroys the electronic transition, while the structure is significantly modified at high charge content. Using density functional theory simulations, we predict an alternative avenue to modulate the structure and the electronic transition in CaFeO{sub 3}. Charge distribution can be modulated using strain-rotation coupling and thin film engineering strategies, proposing themselves as a promising avenue for fine tuning electronic features in transition metal-oxide perovskites.

Realizing the Translational Potential of Telomere Length Variation as a Tissue-Based Prognostic Marker for Prostate Cancer

DTIC Science & Technology

2014-10-01

Telomere Length Variation as a Tissue- Based Prognostic Marker for Prostate Cancer PRINCIPAL INVESTIGATOR: Elizabeth A. Platz CONTRACTING...Translational Potential of Telomere Length Variation as a Tissue- Based Prognostic Marker for Prostate Cancer 5b. GRANT NUMBER W81XWH-12-1-0545 5c...combination of telomere length variability in prostate cancer cells and short telomere length in cancer-associated stromal cells is an independent

Reconcile Planck-scale discreteness and the Lorentz-Fitzgerald contraction

NASA Astrophysics Data System (ADS)

Rovelli, Carlo; Speziale, Simone

2003-03-01

A Planck-scale minimal observable length appears in many approaches to quantum gravity. It is sometimes argued that this minimal length might conflict with Lorentz invariance, because a boosted observer can see the minimal length further Lorentz contracted. We show that this is not the case within loop quantum gravity. In loop quantum gravity the minimal length (more precisely, minimal area) does not appear as a fixed property of geometry, but rather as the minimal (nonzero) eigenvalue of a quantum observable. The boosted observer can see the same observable spectrum, with the same minimal area. What changes continuously in the boost transformation is not the value of the minimal length: it is the probability distribution of seeing one or the other of the discrete eigenvalues of the area. We discuss several difficulties associated with boosts and area measurement in quantum gravity. We compute the transformation of the area operator under a local boost, propose an explicit expression for the generator of local boosts, and give the conditions under which its action is unitary.

Epidural analgesia in early labour blocks the stress response but uterine contractions remain unchanged.

PubMed

Scull, T J; Hemmings, G T; Carli, F; Weeks, S K; Mazza, L; Zingg, H H

1998-07-01

To determine the effect of epidural analgesia on biochemical markers of stress, plasma oxytocin concentrations and frequency of uterine contractions during the first stage of labour. Nine nulliparous women, in spontaneous labour, with a singleton fetus and cervical dilatation < or = 5 cm were enrolled. Epidural bupivacaine 0.25% (range 10-14 ml) was administered and bilateral sensory blockade to ice (T8-L4) achieved. Blood samples were collected before the epidermal block and every 10 min for one hour after the block was achieved for the measurement of plasma beta-endorphin, cortical, glucose, lactate and oxytocin concentrations. No exogenous oxytocin was given. Intensity of pain was assessed at the time of the blood sampling using a 10 cm visual analogue scale (VAS). The frequency of uterine contractions was recorded for 60 min before and after the epidural block. There was a decrease in plasma beta-endorphin and cortisol concentrations after epidural block (P < 0.01). There were no changes in plasma glucose and lactate concentrations. The mean VAS for pain decreased 10 min after epidural block was achieved and remained < 2 throughout the study period (P < 0.001). Mean plasma oxytocin concentrations did not change. The frequency of uterine contractions before and after the epidural block was similar. The metabolic stress response to the pain of labour was attenuated by epidural analgesia. In contrast, plasma oxytocin concentration and frequency of uterine contractions were unaffected by the attenuation of metabolic stress response.

Multiscale Models and Measurements of Muscle Forces

DTIC Science & Technology

2015-03-08

U.S. Army Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 muscle contraction , molecular motors, x-ray diffraction REPORT...thick filament stretching during muscle contraction .  We have completed construction of a new apparatus for measuring simultaneous force, length and

Endoscopic Cold Incision, Balloon Dilation, Mitomycin C Application, and Steroid Injection for Adult Laryngotracheal Stenosis

PubMed Central

Parker, Noah P.; Bandyopadhyay, Dipankar; Misono, Stephanie; Goding, George S.

2017-01-01

Objectives/Hypothesis To describe the presentation, stenosis characteristics, etiological differences, and outcomes of adult laryngotracheal stenosis treated with endoscopic cold incision, balloon dilation, topical mitomycin C application, and steroid injection. Study Design Retrospective chart review. Methods Demographic and clinical data were extracted for patients treated between March 2000 and December 2010. Prolonged intubation and idiopathic patient data were utilized for comparative analysis. Results Eighty patients (65 females; 15 males; 220 procedures; 2.9 years mean follow-up) presented with dyspnea (81%) and/or exercise intolerance (40%). Most commonly, etiologies were idiopathic (53 of 80; 66%) or prolonged intubation (14 of 80; 18%). Mean procedures per patient and interval between procedures were 2.8 procedures and 405 days, respectively. Mean stenosis length and distance from the caudal phonating edge of the true vocal folds were 9 mm and 19 mm. Complication, tracheotomy, and open-procedure rates were 1.8%, 1.4%, and 10.0%, respectively. Patients with more than two procedures demonstrated a mean 4-mm reduction in stenosis length and a 2-mm cephalad progression of stenosis over time. More caudal stenoses required more frequent procedures. Procedures were less frequent as more procedures were performed. Stenosis characteristics, interval between procedures, and total procedures were similar between idiopathic patients with or without intubation histories, but different between idiopathic and prolonged intubation patients. Conclusions This procedure was shown to be a viable option in adult laryngotracheal stenosis. Repeat dilation was likely, but was performed without adversely affecting stenosis characteristics. Stenoses farther from the vocal folds required procedures more frequently. Idiopathic patients with a history of brief, elective intubation had stenosis characteristics and responses to therapy similar to idiopathic patients without an intubation history. Both idiopathic groups together demonstrated stenosis characteristics and responses to therapy dissimilar to patients with a history of prolonged intubation. PMID:23086662

30 CFR 1206.151 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... interests regarding that contract. To be considered arm's length for any production month, a contract must.... Gathering means the movement of lease production to a central accumulation and/or treatment point on the... the lessee's production and to market that production. Minimum royalty means that minimum amount of...

30 CFR 1206.151 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... interests regarding that contract. To be considered arm's length for any production month, a contract must.... Gathering means the movement of lease production to a central accumulation and/or treatment point on the... the lessee's production and to market that production. Minimum royalty means that minimum amount of...

30 CFR 206.151 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... interests regarding that contract. To be considered arm's length for any production month, a contract must.... Gathering means the movement of lease production to a central accumulation and/or treatment point on the... the lessee's production and to market that production. Minimum royalty means that minimum amount of...

48 CFR 22.1021 - Requests for hearing.

Code of Federal Regulations, 2010 CFR

2010-10-01

... SOCIOECONOMIC PROGRAMS APPLICATION OF LABOR LAWS TO GOVERNMENT ACQUISITIONS Service Contract Act of 1965, as... services to be performed under the contract; (4) The status of the procurement and any estimated... length negotiations; (2) A statement regarding the status of the procurement and any estimated...

Slack length reduces the contractile phenotype of the Swine carotid artery.

PubMed

Rembold, Christopher M; Garvey, Sean M; Tejani, Ankit D

2013-01-01

Contraction is the primary function of adult arterial smooth muscle. However, in response to vessel injury or inflammation, arterial smooth muscle is able to phenotypically modulate from the contractile state to several 'synthetic' states characterized by proliferation, migration and/or increased cytokine secretion. We examined the effect of tissue length (L) on the phenotype of intact, isometrically held, initially contractile swine carotid artery tissues. Tissues were studied (1) without prolonged incubation at the optimal length for force generation (1.0 Lo, control), (2) with prolonged incubation for 17 h at 1.0 Lo, or (3) with prolonged incubation at slack length (0.6 Lo) for 16 h and then restoration to 1.0 Lo for 1 h. Prolonged incubation at 1.0 Lo minimally reduced the contractile force without substantially altering the mediators of contraction (crossbridge phosphorylation, shortening velocity or stimulated actin polymerization). Prolonged incubation of tissues at slack length (0.6 Lo), despite return of length to 1.0 Lo, substantially reduced contractile force, reduced crossbridge phosphorylation, nearly abolished crossbridge cycling (shortening velocity) and abolished stimulated actin polymerization. These data suggest that (1) slack length treatment significantly alters the contractile phenotype of arterial tissue, and (2) slack length treatment is a model to study acute phenotypic modulation of intact arterial smooth muscle. Copyright © 2013 S. Karger AG, Basel.

Pyloric localisation in 57 dogs of breeds susceptible to gastric dilatation-volvulus in the UK using computed tomography.

PubMed

Tomlinson, A W; Lillis, S M; German, A J; Burrow, R D

2016-12-17

Describe the location of the pylorus using CT in dog breeds susceptible to gastric dilatation-volvulus in the UK. Descriptive anatomical study. Abdominal CT scans of 57 client-owned dogs were reviewed to assess pyloric position relative to the 9th, 10th, 11th and 13th ribs and 2 and 3 cm caudal to the 13th rib at the 8, 9 and 10 o'clock positions. The angle of the pylorus from the centre of the abdominal cavity relative to the sagittal plane was also determined. In 88 per cent of cases, the pylorus was located in the right cranioventral abdomen with 63 per cent positioned at the 9-10 o'clock position. The overall distance between the pylorus and right abdominal wall (RAW) at the 13th rib 10 o'clock position was equivalent to 29 per cent of ventral abdominal length, significantly greater than the median overall distance of ∼14 per cent of ventral abdominal length between the pylorus and RAW at the 9th or 10th rib 10 o'clock position (P<0.0001). Common gastropexy locations may result in considerable displacement of the pylorus relative to its natural anatomic location. Further case-control studies are required to assess the clinical significance of this finding. British Veterinary Association.

Evaluation of an endoscopically assisted gastropexy technique in dogs.

PubMed

Dujowich, Mauricio; Reimer, S Brent

2008-04-01

To evaluate the use of endoscopy in conjunction with a gastropexy technique in dogs as a potential means to aid prevention of gastric dilatation-volvulus. 12 healthy adult medium- and large-breed dogs. 12 adult research dogs that had no abnormal physical examination findings each underwent an endoscopically assisted gastropexy procedure. On completion of the procedure, the dogs were euthanized and exploratory laparotomies were performed to evaluate the surgical site. Data recorded included anatomic location of the gastropexy, gastropexy length, and duration of procedure as well as any complications. Mean+/-SD gastropexy length was 3.3+/-0.25 cm, and mean duration of surgery was 18+/-7 minutes. In each dog, the stomach was located in its normal anatomic position and all gastropexies were sutured to the abdominal wall at the level of the pyloric antrum. The only complications during the procedure were needle bending and breakage at the time of stay suture placement. On the basis of these findings, it appears that endoscopically assisted gastropexy is a simple, fast, safe, and reliable method of performing a prophylactic gastropexy in dogs when undertaken by a person who is skilled in endoscopy. Such a procedure maximizes the benefits of decreased morbidity and shorter duration of anesthesia associated with minimally invasive surgery. Further clinical studies are warranted to evaluate the long-term efficacy of this procedure in dogs at risk for development of gastric dilatation-volvulus.

Contraction-free, fume-fixed longitudinal sections of fresh frozen muscle

NASA Technical Reports Server (NTRS)

Riley, Danny A.; Slocum, Glenn R.

1988-01-01

Contraction damage occurring when longitudinal frozen sections of fresh unfixed muscles are thawed on microscope slides has limited histological examination of this tissue mainly to cross sections. Longitudinally oriented sections are advantageous for investigating properties that vary along the length of the muscle fibers. A fume fixation technique has been developed for preventing contraction of thick longitudinal frozen sections. The technique is compatible with histochemical staining of enzymes.

Mechanisms of right ventricular electromechanical dyssynchrony and mechanical inefficiency in children after repair of tetralogy of fallot.

PubMed

Hui, Wei; Slorach, Cameron; Dragulescu, Andreea; Mertens, Luc; Bijnens, Bart; Friedberg, Mark K

2014-07-01

Right bundle branch block and right ventricular (RV) dysfunction are common after tetralogy of Fallot repair (rTOF). We hypothesized that right bundle branch block is associated with specific RV mechanical dyssynchrony and inefficient contraction. We studied rTOF children and age-matched controls. QRS duration and morphology were assessed. RV mechanical dyssynchrony, indicated by early septal activation (right-sided septal flash), RV lateral wall prestretch/late contraction, postsystolic shortening, and intraventricular delay were analyzed using 2-dimensional strain echocardiography. Peak oxygen consumption reflected exercise capacity. Pulmonary regurgitation and RV volumes were assessed by MRI. Forty-six rTOF patients and 46 controls were studied. Ninety-three percent of rTOF patients demonstrated a right-sided septal flash with simultaneous RV basal lateral wall prestretch/late activation. The RV basal segment was the most delayed in onset (115 [0-194] versus 35 [0-96] ms) and termination (462 [369-706] versus 412 [325-529] ms) of longitudinal shortening, with postsystolic shortening. QRS duration correlated with RV basal time to onset and peak shortening (P<0.05). Intra-RV delay was higher in rTOF (P<0.05) in association with RV dilatation (r=0.33; P=0.04). In rTOF, RV mechanics were inefficient, with prestretch and postsystolic shortening comprising 15±11% and 16±9% of total shortening, respectively. A composite parameter of electric and mechanical dyssynchrony correlated with RV end-diastolic volume (r=0.39; P=0.03). Typical electromechanical dyssynchrony associated with mechanical inefficiency, regional dysfunction, and RV dilatation is common in rTOF children, possibly contributing to progressive RV dysfunction. The potential of cardiac resynchronization in appropriate patients requires further study. © 2014 American Heart Association, Inc.

Upper airway muscles awake and asleep.

PubMed

Sériès, Frédéric

2002-06-01

Upper airway (UA) structures are involved in different respiratory and non-respiratory tasks. The coordination of agonist and antagonist UA dilators is responsible for their mechanical function and their ability to maintain UA patency throughout the respiratory cycle. The activity of these muscles is linked with central respiratory activity but also depends on UA pressure changes and is greatly influenced by sleep. UA muscles are involved in determining UA resistance and stability (i.e. closing pressure), and the effect of sleep on these variables may be accounted for by its effect on tonic and phasic skeletal muscle activities. The mechanical effects of UA dilator contraction also depend on their physiological properties (capacity to generate tension in vitro, activity of the anaerobic enzymatic pathway, histo-chemical characteristics that may differ between subjects who may or may not have sleep-related obstructive breathing disorders). These characteristics may represent an adaptive process to an increased resistive loading of these muscles. The apparent discrepancy between the occurrence of UA closure and an increased capacity to generate tension in sleep apnea patients may be due to a reduction in the effectiveness of UA muscle contraction in these patients; such an increase in tissue stiffness could be accounted for by peri-muscular tissue characteristics. Therefore, understanding of UA muscle physiological characteristics should take into account its capacity for force production and its mechanical coupling with other UA tissues. Important research goals for the future will be to integrate these issues with other physiological features of the disease, such as UA size and dimension, histological characteristics of UA tissues and the effect of sleep on muscle function. Such integration will better inform understanding of the role of pharyngeal UA muscles in the pathophysiology of the sleep apnea/hypopnea syndrome.

New Endoscopic Indicator of Esophageal Achalasia: “Pinstripe Pattern”

PubMed Central

Minami, Hitomi; Isomoto, Hajime; Miuma, Satoshi; Kobayashi, Yasutoshi; Yamaguchi, Naoyuki; Urabe, Shigetoshi; Matsushima, Kayoko; Akazawa, Yuko; Ohnita, Ken; Takeshima, Fuminao; Inoue, Haruhiro; Nakao, Kazuhiko

2015-01-01

Background and Study Aims Endoscopic diagnosis of esophageal achalasia lacking typical endoscopic features can be extremely difficult. The aim of this study was to identify simple and reliable early indicator of esophageal achalasia. Patients and Methods This single-center retrospective study included 56 cases of esophageal achalasia without previous treatment. As a control, 60 non-achalasia subjects including reflux esophagitis and superficial esophageal cancer were also included in this study. Endoscopic findings were evaluated according to Descriptive Rules for Achalasia of the Esophagus as follows: (1) esophageal dilatation, (2) abnormal retention of liquid and/or food, (3) whitish change of the mucosal surface, (4) functional stenosis of the esophago-gastric junction, and (5) abnormal contraction. Additionally, the presence of the longitudinal superficial wrinkles of esophageal mucosa, “pinstripe pattern (PSP)” was evaluated endoscopically. Then, inter-observer diagnostic agreement was assessed for each finding. Results The prevalence rates of the above-mentioned findings (1–5) were 41.1%, 41.1%, 16.1%, 94.6%, and 43.9%, respectively. PSP was observed in 60.7% of achalasia, while none of the control showed positivity for PSP. PSP was observed in 26 (62.5%) of 35 cases with shorter history < 10 years, which usually lacks typical findings such as severe esophageal dilation and tortuosity. Inter-observer agreement level was substantial for food/liquid remnant (k = 0.6861) and PSP (k = 0.6098), and was fair for abnormal contraction and white change. The accuracy, sensitivity, and specificity for achalasia were 83.8%, 64.7%, and 100%, respectively. Conclusion “Pinstripe pattern” could be a reliable indicator for early discrimination of primary esophageal achalasia. PMID:25664812

Étalement d'une goutte stratifiée incompressible

NASA Astrophysics Data System (ADS)

de Gennes, Pierre-Gilles; Cazabat, Anne-Marie

L'étalement de films ultraminces de liquides simples sur une surface lisse horizontale conduit souvent à des gouttes à gradins d'une épaisseur moléculaire ([1]-[3]). Nous construisons ici un modèle pour la dynamique de l'étalement, en supposant que : (a) chaque gradin est un liquide bidimensionnel incompressible; (b) les molécules de la n-ième couche sont soumises à un potentiel (Wn) qui exprime leurs interactions à longue portée avec le solide; (c) on a un écoulement parallèle de cisaillement, et un écoulement normal de perméation. La perméation intervient seulement dans un certain « ruban » de largeur ξ sur le bord de chaque gradin. Dans le cas usuel, où le rayon du n-ième gradin Rn est trs supérieur à ξ, la dissipation est dominée par le cisaillement, et on arrive à des lois simples pour la vitesse de dilatation (ou de contraction) dotR_n. Very thin films of simple liquids often spread with well defined steps of molecular thickness ([1]-[3]). We construct a model for the dynamics of spreading assuming that: (a) each layer is an incompressible, 2 dimensional fluid; (b) the molecules in the (nth) layer experience a long range potential (e.g. Van der Waals) from the solid; (c) two types of flow occur: shear between layers and permeation normal to the layers. We find that permeation is important only in an annulus of small size ξ near each step. Between steps, the viscous effects in simple shear dominate, and this leads to simple laws for the dilation (or contraction) of the various layers.

Labor progress indices and dynamics of the individual uterine contraction during the active stage of labor.

PubMed

Ophir, Ella; Bornstein, Jacob; Odeh, Marwan; Kaminsky, Svetlana; Shnaider, Oleg; Megel, Yuri; Barnea, Ofer

2014-03-01

To obtain and study new data on the dynamics of the labor process and to develop a contraction-based index of labor progress. This study was carried out at the Delivery Room, Department of Obstetrics and Gynecology, Western Galilee Hospital, Nahariya, Israel, using a new device (Birth Track). We continuously monitored cervical dilatation (CD) and head descent (HD) in 30 nulliparaous women during active labor with (augmented group) and without (study group) oxytocin augmentation. This led to the development and validation of progress indices based on features extracted from continuous monitoring. There were no significant differences between the average of each parameter in the study and augmented groups, except for HD velocity. Average HD velocity was faster in the study group. Linear regression analyses demonstrated that head station (HS) amplitude and Toco amplitude were the best parameters for predicting HD velocity in both groups. In the study group, average HD velocity was also significantly related to Toco rate and contraction efficiency. In the augmented group, only a weak correlation with Toco rate was seen, and no correlation with contraction efficiency. With the assistance of the Birth Track device, we can obtain continuous data on the labor process and indices to estimate the labor progress process without the use of vaginal (manual) examination. © 2013 The Authors. Journal of Obstetrics and Gynaecology Research © 2013 Japan Society of Obstetrics and Gynecology.

30 CFR 1206.151 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... interests regarding that contract. To be considered arm's length for any production month, a contract must.... Gathering means the movement of lease production to a central accumulation and/or treatment point on the... is to acquire only the lessee's production and to market that production. Minimum royalty means that...

The series-elastic shock absorber: tendons attenuate muscle power during eccentric actions.

PubMed

Roberts, Thomas J; Azizi, Emanuel

2010-08-01

Elastic tendons can act as muscle power amplifiers or energy-conserving springs during locomotion. We used an in situ muscle-tendon preparation to examine the mechanical function of tendons during lengthening contractions, when muscles absorb energy. Force, length, and power were measured in the lateral gastrocnemius muscle of wild turkeys. Sonomicrometry was used to measure muscle fascicle length independently from muscle-tendon unit (MTU) length, as measured by a muscle lever system (servomotor). A series of ramp stretches of varying velocities was applied to the MTU in fully activated muscles. Fascicle length changes were decoupled from length changes imposed on the MTU by the servomotor. Under most conditions, muscle fascicles shortened on average, while the MTU lengthened. Energy input to the MTU during the fastest lengthenings was -54.4 J/kg, while estimated work input to the muscle fascicles during this period was only -11.24 J/kg. This discrepancy indicates that energy was first absorbed by elastic elements, then released to do work on muscle fascicles after the lengthening phase of the contraction. The temporary storage of energy by elastic elements also resulted in a significant attenuation of power input to the muscle fascicles. At the fastest lengthening rates, peak instantaneous power input to the MTU reached -2,143.9 W/kg, while peak power input to the fascicles was only -557.6 W/kg. These results demonstrate that tendons may act as mechanical buffers by limiting peak muscle forces, lengthening rates, and power inputs during energy-absorbing contractions.

Scalar dissipation, diffusion and dilatation in turbulent H2-air premixed flames with complex chemistry

NASA Astrophysics Data System (ADS)

Swaminathan, N.; Bilger, R. W.

2001-09-01

Characteristics of the scalar dissipation rate, N, of a progress variable, c, based on temperature in turbulent H2-air premixed flames are studied via direct numerical simulation with complex chemical kinetics for a range of flow/flame conditions (Baum et al 1994 J. Fluid Mech. 281 1). The flames are in the usually designated wrinkled-flamelet and well-stirred reactor regimes. The normalized conditional average, Nζ+, is observed to be higher than the corresponding planar laminar value because of strain thinning and the augmentation of laminar transport by turbulence within the flame front. Also, Nζ+ varies strongly across the flame-brush when u'/Sl is high. N has a log-normal distribution when u'/Sl is small and has a long negative tail for cases where u'/Sl is large. In the flame with φ = 0.5, \\widetilde{N_{\\zeta}^ + }/\\widetilde{N_^ + }" shows some sensitivity to Pζ and the sensitivity seems to be weak in a φ = 0.35 flame. The effect of turbulence on <ζ> is observed to be marginal. The conditional diffusion and the conditional dilatation, <∇ · u|ζ>, peak on the unburnt side of the flame-front and are higher than the corresponding laminar flame values in all cases. The inter-relationship among the conditional dissipation, diffusion, dilatation and velocity is discussed. A model for uζ obtained from the conditional dilatation is found not to perform as well as a linear model. The above results are limited, however, because, the flow field is two dimensional, hydrogen is used as the fuel, the range of dynamic length scales is small and the sample size is small.

Heart failure: when form fails to follow function.

PubMed

Katz, Arnold M; Rolett, Ellis L

2016-02-01

Cardiac performance is normally determined by architectural, cellular, and molecular structures that determine the heart's form, and by physiological and biochemical mechanisms that regulate the function of these structures. Impaired adaptation of form to function in failing hearts contributes to two syndromes initially called systolic heart failure (SHF) and diastolic heart failure (DHF). In SHF, characterized by high end-diastolic volume (EDV), the left ventricle (LV) cannot eject a normal stroke volume (SV); in DHF, with normal or low EDV, the LV cannot accept a normal venous return. These syndromes are now generally defined in terms of ejection fraction (EF): SHF became 'heart failure with reduced ejection fraction' (HFrEF) while DHF became 'heart failure with normal or preserved ejection fraction' (HFnEF or HFpEF). However, EF is a chimeric index because it is the ratio between SV--which measures function, and EDV--which measures form. In SHF the LV dilates when sarcomere addition in series increases cardiac myocyte length, whereas sarcomere addition in parallel can cause concentric hypertrophy in DHF by increasing myocyte thickness. Although dilatation in SHF allows the LV to accept a greater venous return, it increases the energy cost of ejection and initiates a vicious cycle that contributes to progressive dilatation. In contrast, concentric hypertrophy in DHF facilitates ejection but impairs filling and can cause heart muscle to deteriorate. Differences in the molecular signals that initiate dilatation and concentric hypertrophy can explain why many drugs that improve prognosis in SHF have little if any benefit in DHF. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

[Endoscopic treatment of oesophageal sténosis using Celestin prosthesis (author's transl)].

PubMed

Célestin, L R; Etienne, J; Raimbert, P; Fallouh, H; Sultan, R

The Celestin pulsion tube introduced by endoscopy seems to constitute a satisfactory method of dealing with oesophageal strictures, both malignant and benign. The site and histology of the tumour, as well as the diameter of the remaining lumen are determined by an initial endoscopic examination. The Eder-Puestow guide wire, essential to safe dilatation and intubation, may be introduced in various ways depending upon the size, length and nature of the stenosis: it may be threaded through the lumen with a fiberoscope under radiological control, or after drilling with laser. Subsequent dilatation may be carried out with olive-shaped metal dialtors, stepped plastic dilators of laminaria, depending upon the degree of fibrosis and the risks of fissuration. A final diameter of 17 mm is advisable. The pulsion tube, with its soft anti-migration skirt, is positioned using an introducer mounted on a semi-rigid mandrin or sliding over a fiberoscope. Its position must be checked at three-monthly intervals. The authors have used this method in 115 patients, 24 of whom had benign lesions and 91 malignant lesions. Among the latter, 23 had been irradiated, 7 were post-anatomotic and 61 had never been treated. There were 5 cases of mediatinitis and one of haemorrhage. Eleven tight strictures, wich had resisted dilatation with metal olive yieled laminaria. The longest follow-ups are of 19 months for malignant stenose and 40 months for benign stenoses. The main indications are malignant stenoses, irrespective of whether they have been irradiated or not, and peptic stenoses in inopereable patients. The procedure restores normal oral feeding, thereby avoiding the need for gastrostomy or jejunostomy.

Realizing the Translational Potential of Telomere Length Variation as a Tissue Based Prognostic Marker for Prostate Cancer

DTIC Science & Technology

2016-10-01

Award Number: W81XWH-12-1-0545 TITLE: Realizing the Translational Potential of Telomere Length Variation as a Tissue- Based Prognostic Marker for...30 Sep 2015 - 29 Sep 2016 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Realizing the Translational Potential of Telomere Length Variation as a Tissue...HPFS), whether the combination of telomere length variability in prostate cancer cells and short telomere length in cancer-associated stromal cells is

Influences of Fascicle Length During Isometric Training on Improvement of Muscle Strength.

PubMed

Tanaka, Hiroki; Ikezoe, Tome; Umehara, Jun; Nakamura, Masatoshi; Umegaki, Hiroki; Kobayashi, Takuya; Nishishita, Satoru; Fujita, Kosuke; Araki, Kojiro; Ichihashi, Noriaki

2016-11-01

Tanaka, H, Ikezoe, T, Umehara, J, Nakamura, M, Umegaki, H, Kobayashi, T, Nishishita, S, Fujita, K, Araki, K, and Ichihashi, N. Influences of fascicle length during isometric training on improvement of muscle strength. J Strength Cond Res 30(11): 3249-3255, 2016-This study investigated whether low-intensity isometric training would elicit a greater improvement in maximum voluntary contraction (MVC) at the same fascicle length, rather than the joint angle, adopted during training. Sixteen healthy women (21.8 ± 1.5 years) were randomly divided into an intervention group and a control group. Before (Pre) and after (Post) training, isometric plantarflexion MVCs were measured every 10° through the range of ankle joint position from 20° dorsiflexion to 30° plantarflexion (i.e., 6 ankle angles). Medial gastrocnemius fascicle length was also measured at each position, using B-mode ultrasound under 3 conditions of muscle activation: at rest, 30%MVC at respective angles, and MVC. Plantarflexion resistance training at an angle of 20° plantarflexion was performed 3 days a week for 4 weeks at 30%MVC using 3 sets of twenty 3-second isometric contractions. Maximum voluntary contraction in the intervention group increased at 0 and 10° plantarflexion (0°; Pre: 81.2 ± 26.5 N·m, Post: 105.0 ± 21.6 N·m, 10°; Pre: 63.0 ± 23.6 N·m, Post: 81.3 ± 20.3 N·m), which was not the angle used in training (20°). However, the fascicle length adopted in training at 20° plantarflexion and 30%MVC was similar to the value at 0 or 10° plantarflexion at MVC. Low-intensity isometric training at a shortened muscle length may be effective for improving MVC at a lengthened muscle length because of specificity of the fascicle length than the joint angle.

Sarcomere length-dependence of activity-dependent twitch potentiation in mouse skeletal muscle

PubMed Central

Rassier, Dilson E; MacIntosh, Brian R

2002-01-01

Background It has been reported that potentiation of a skeletal muscle twitch response is proportional to muscle length with a negative slope during staircase, and a positive slope during posttetanic potentiation. This study was done to directly compare staircase and posttetanic responses with measurement of sarcomere length to compare their length-dependence. Methods Mouse extensor digitorum longus (EDL) muscles were dissected to small bundles of fibers, which permit measurement of sarcomere length (SL), by laser diffraction. In vitro fixed-end contractions of EDL fiber bundles were elicited at 22°C and 35°C at sarcomere lengths ranging from 2.35 μm to 3.85 μm. Twitch contractions were assessed before and after 1.5 s of 75 Hz stimulation at 22°C or during 10 s of 10 Hz stimulation at 22°C or 35°C. Results Staircase potentiation was greater at 35°C than 22°C, and the relative magnitude of the twitch contraction (Pt*/Pt) was proportional to sarcomere length with a negative slope, over the range 2.3 μm – 3.7 μm. Linear regression yielded the following: Pt*/Pt = -0.59·SL+3.27 (r2 = 0.74); Pt*/Pt = -0.39·SL+2.34 (r2 = 0.48); and Pt*/Pt = -0.50·SL+2.45 (r2 = 0.80) for staircase at 35°C, and 22°C and posttetanic response respectively. Posttetanic depression rather than potentiation was present at long SL. This indicates that there may be two processes operating in these muscles to modulate the force: one that enhances and a second that depresses the force. Either or both of these processes may have a length-dependence of its mechanism. Conclusion There is no evidence that posttetanic potentiation is fundamentally different from staircase in these muscles. PMID:12475395

The assessment of labor: a brief history.

PubMed

Cohen, Wayne R; Friedman, Emanuel A

2018-01-26

In the 1930s, investigators in the US, Germany and Switzerland made the first attempts to quantify the course of labor in a clinically meaningful way. They emphasized the rupture of membranes as a pivotal event governing labor progress. Attention was also placed on the total number of contractions as a guide to normality. Beginning in the 1950s, Friedman determined that changes in cervical dilatation and fetal station over time were the most useful parameters for the assessment of labor progress. He showed all normal labors had similar patterns of dilatation and descent, differing only in the durations and slopes of their component parts. These observations led to the formulation of criteria that elevated the assessment of labor from a rather arbitrary exercise to one guided by scientific objectivity. Researchers worldwide confirmed the basic nature of labor curves and validated their functionality. This system allows us to quantify the effects of parity, analgesia, maternal obesity, prior cesarean, maternal age, and fetal presentation and position on labor. It permits analysis of outcomes associated with labor aberrations, quantifies the effectiveness of treatments and assesses the need for cesarean delivery. Also, dysfunctional labor patterns serve as indicators of short- and long-term risks to offspring. We still lack the necessary translational research to link the physiologic manifestations of uterine contractility with changes in dilatation and descent. Recent efforts to interpret electrohysterographic patterns hold promise in this regard, as does preliminary exploration into the molecular basis of dysfunctional labor. For now, the clinician is best served by a system of labor assessment proposed more than 60 years ago and embellished upon in considerable detail since.

Contraction of gut smooth muscle cells assessed by fluorescence imaging.

PubMed

Tokita, Yohei; Akiho, Hirotada; Nakamura, Kazuhiko; Ihara, Eikichi; Yamamoto, Masahiro

2015-03-01

Here we discuss the development of a novel cell imaging system for the evaluation of smooth muscle cell (SMC) contraction. SMCs were isolated from the circular and longitudinal muscular layers of mouse small intestine by enzymatic digestion. SMCs were stimulated by test agents, thereafter fixed in acrolein. Actin in fixed SMCs was stained with phalloidin and cell length was determined by measuring diameter at the large end of phalloidin-stained strings within the cells. The contractile response was taken as the decrease in the average length of a population of stimulated-SMCs. Various mediators and chemically identified compounds of daikenchuto (DKT), pharmaceutical-grade traditional Japanese prokinetics, were examined. Verification of the integrity of SMC morphology by phalloidin and DAPI staining and semi-automatic measurement of cell length using an imaging analyzer was a reliable method by which to quantify the contractile response. Serotonin, substance P, prostaglandin E2 and histamine induced SMC contraction in concentration-dependent manner. Two components of DKT, hydroxy-α-sanshool and hydroxy-β-sanshool, induced contraction of SMCs. We established a novel cell imaging technique to evaluate SMC contractility. This method may facilitate investigation into SMC activity and its role in gastrointestinal motility, and may assist in the discovery of new prokinetic agents. Copyright © 2015 Japanese Pharmacological Society. Production and hosting by Elsevier B.V. All rights reserved.

41 CFR 102-74.485 - Is there any limitation on the length of time of a permit?

Code of Federal Regulations, 2010 CFR

2010-07-01

... on the length of time of a permit? 102-74.485 Section 102-74.485 Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION REAL... limitation on the length of time of a permit? Yes, a permit may not be issued for a period of time in excess...

41 CFR 102-74.485 - Is there any limitation on the length of time of a permit?

Code of Federal Regulations, 2011 CFR

2011-01-01

... on the length of time of a permit? 102-74.485 Section 102-74.485 Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION REAL... limitation on the length of time of a permit? Yes, a permit may not be issued for a period of time in excess...

The use of an "unnatural" prostaglandin in the termination of pregnancy.

PubMed

Gillespie, A; Beazley, J M; van Dorp, D A

1971-04-01

An unnatural prostaglandin (PG) (prepared by biosynthesis using the method described by Vonkerman et al.) was used to terminate midtrimester pregnancy in 3 primiparous patients aged 21-24. The PG was administered intravenously using a Palmer slow infusion pump. The patients were monitored continuously with particular attention given to pulse, respiration, blood pressure, uterine contractions and cervical dilatation. All 3 cases successfully aborted. Effective infusion rate was similar to that of PGE1 and PGE2 (5-6 mcg/minute) and side effects were trivial (minimal skin flushing, vomiting, mild urticarial reaction). 2 of the patients aborted 8 and 22 hours after infusion stopped without being conscious of continuing uterine activity; the 3rd patient necessitated infusion on the 2nd day and exhibited increased response to the infusion; however, the PG supply was exhausted and syntocinon infusion facilitated the complete abortion. This study shows that this synthetic prostaglandin containing an uneven number of carbon atoms is pharmacologically active and can induce contractions in the intact human pregnant uterus.

hnRNP U protein is required for normal pre-mRNA splicing and postnatal heart development and function.

PubMed

Ye, Junqiang; Beetz, Nadine; O'Keeffe, Sean; Tapia, Juan Carlos; Macpherson, Lindsey; Chen, Weisheng V; Bassel-Duby, Rhonda; Olson, Eric N; Maniatis, Tom

2015-06-09

We report that mice lacking the heterogeneous nuclear ribonucleoprotein U (hnRNP U) in the heart develop lethal dilated cardiomyopathy and display numerous defects in cardiac pre-mRNA splicing. Mutant hearts have disorganized cardiomyocytes, impaired contractility, and abnormal excitation-contraction coupling activities. RNA-seq analyses of Hnrnpu mutant hearts revealed extensive defects in alternative splicing of pre-mRNAs encoding proteins known to be critical for normal heart development and function, including Titin and calcium/calmodulin-dependent protein kinase II delta (Camk2d). Loss of hnRNP U expression in cardiomyocytes also leads to aberrant splicing of the pre-mRNA encoding the excitation-contraction coupling component Junctin. We found that the protein product of an alternatively spliced Junctin isoform is N-glycosylated at a specific asparagine site that is required for interactions with specific protein partners. Our findings provide conclusive evidence for the essential role of hnRNP U in heart development and function and in the regulation of alternative splicing.

Patching C2n Time Series Data Holes using Principal Component Analysis

DTIC Science & Technology

2007-01-01

characteristic local scale exponent , regardless of dilation of the length examined. THE HURST PARAMETER There are a slew of methods13 available to...fractal dimension D0, which characterises the roughness of the data, and the Hurst parameter, H , which is a measure of the long range dependence (LRD...estimate H . For simplicity, we have opted to use the well known Hurst –Mandelbrot R/S technique, which is also the most elementary. The fitting curve

Fluid dynamics alter Caenorhabditis elegans body length via TGF-β/DBL-1 neuromuscular signaling

PubMed Central

Harada, Shunsuke; Hashizume, Toko; Nemoto, Kanako; Shao, Zhenhua; Higashitani, Nahoko; Etheridge, Timothy; Szewczyk, Nathaniel J; Fukui, Keiji; Higashibata, Akira; Higashitani, Atsushi

2016-01-01

Skeletal muscle wasting is a major obstacle for long-term space exploration. Similar to astronauts, the nematode Caenorhabditis elegans displays negative muscular and physical effects when in microgravity in space. It remains unclear what signaling molecules and behavior(s) cause these negative alterations. Here we studied key signaling molecules involved in alterations of C. elegans physique in response to fluid dynamics in ground-based experiments. Placing worms in space on a 1G accelerator increased a myosin heavy chain, myo-3, and a transforming growth factor-β (TGF-β), dbl-1, gene expression. These changes also occurred when the fluid dynamic parameters viscosity/drag resistance or depth of liquid culture were increased on the ground. In addition, body length increased in wild type and body wall cuticle collagen mutants, rol-6 and dpy-5, grown in liquid culture. In contrast, body length did not increase in TGF-β, dbl-1, or downstream signaling pathway, sma-4/Smad, mutants. Similarly, a D1-like dopamine receptor, DOP-4, and a mechanosensory channel, UNC-8, were required for increased dbl-1 expression and altered physique in liquid culture. As C. elegans contraction rates are much higher when swimming in liquid than when crawling on an agar surface, we also examined the relationship between body length enhancement and rate of contraction. Mutants with significantly reduced contraction rates were typically smaller. However, in dop-4, dbl-1, and sma-4 mutants, contraction rates still increased in liquid. These results suggest that neuromuscular signaling via TGF-β/DBL-1 acts to alter body physique in response to environmental conditions including fluid dynamics. PMID:28725724

In vitro models of tail contraction and cytoplasmic streaming in amoeboid cells.

PubMed

Janson, L W; Taylor, D L

1993-10-01

We have developed a reconstituted gel-sol and contractile model system that mimics the structure and dynamics found at the ectoplasm/endoplasm interface in the tails of many amoeboid cells. We tested the role of gel-sol transformations of the actin-based cytoskeleton in the regulation of contraction and in the generation of endoplasm from ectoplasm. In a model system with fully phosphorylated myosin II, we demonstrated that either decreasing the actin filament length distribution or decreasing the extent of actin filament cross-linking initiated both a weakening of the gel strength and contraction. However, streaming of the solated gel components occurred only under conditions where the length distribution of actin was decreased, causing a self-destruct process of continued solation and contraction of the gel. These results offer significant support that gel strength plays an important role in the regulation of actin/myosin II-based contractions of the tail cortex in many amoeboid cells as defined by the solation-contraction coupling hypothesis (Taylor, D. L., and M. Fechheimer. 1982. Phil. Trans. Soc. Lond. B. 299:185-197). The competing processes of solation and contraction of the gel would appear to be mutually exclusive. However, it is the temporal-spatial balance of the rate and extent of two stages of solation, coupled to contraction, that can explain the conversion of gelled ectoplasm in the tail to a solated endoplasm within the same small volume, generation of a force for the retraction of tails, maintenance of cell polarity, and creation of a positive hydrostatic pressure to push against the newly formed endoplasm. The mechanism of solation-contraction of cortical cytoplasm may be a general component of the normal movement of a variety of amoeboid cells and may also be a component of other contractile events such as cytokinesis.

Size, History-Dependent, Activation and Three-Dimensional Effects on the Work and Power Produced During Cyclic Muscle Contractions.

PubMed

Ross, Stephanie A; Ryan, David S; Dominguez, Sebastian; Nigam, Nilima; Wakeling, James M

2018-05-03

Muscles undergo cycles of length change and force development during locomotion, and these contribute to their work and power production to drive body motion. Muscle fibres are typically considered to be linear actuators whose stress depends on their length, velocity, and activation state, and whose properties can be scaled up to explain the function of whole muscles. However, experimental and modelling studies have shown that a muscle's stress additionally depends on inactive and passive tissues within the muscle, the muscle's size, and its previous contraction history. These effects have not been tested under common sets of contraction conditions, especially the cyclic contractions that are typical of locomotion. Here we evaluate the relative effects of size, history-dependent, activation and three-dimensional effects on the work and power produced during cyclic contractions of muscle models. Simulations of muscle contraction were optimized to generate high power outputs: this resulted in the muscle models being largely active during shortening, and inactive during lengthening. As such, the history-dependent effects were dominated by force depression during simulated active shortening rather than force enhancement during active stretch. Internal work must be done to deform the muscle tissue, and to accelerate the internal muscle mass, resulting in reduced power and work that can be done on an external load. The effect of the muscle mass affects the scaling of muscle properties, with the inertial costs of contraction being relatively greater at larger sizes and lower activation levels.

[Cadmium citotoxicity in mice hepatocytes and implications on tropical environments].

PubMed

Marcano, Letty; Faría, Clarisa de R; Carruyo, Ingrid; Montiel, Xiomara

2006-06-01

We analyzed phenotypic, structural and ultrastructural alterations induced by Cd+2 in hepatocytes extracted from Swiss Albino mice. Cadmium was given orally in watery solution of CdCl2 during 100 days at concentrations of 50 ppm, 100 ppm and 150 ppm. In controls, distilled water alone was used. The samples were processed with the paraffin inclusion and hematoxilin-eosin coloration techniques for light microscopy. For transmission electron microscopy we used the conventional technique. We found phenotypic (size and weight differences) and physiologic changes (muscular weakness, unrest); at the structural level we noticed loss of trabecular disposition and of lobulillar architecture, lymphocyte agglomeration, vacuolization, dilatation of sinusoid and central vein, among others. The ultrastructural study evidenced alterations coincident with those seen with light microscopy, which were accentuated with the increase of metal concentration: nucleolus with a high number of fibrillar centers (50 ppm); voluminous lipidic drops in the cytoplasm, loose endoplasmic rough reticulum, citoplasmatic vacuolization, altered lisosomes and peroxisomes (100 ppm); contracted nuclei with condensed cromatine, dilatation of intracellular space and mitochondria, and loss of fibrillar areas (150 ppm). Cadmium produces a toxic effect in the hepatic cells; the effect is more severe at higher concentration, leading to cellular necrosis.

Evidence for subduction in the ice shell of Europa

NASA Astrophysics Data System (ADS)

Kattenhorn, Simon A.; Prockter, Louise M.

2014-10-01

Jupiter’s icy moon Europa has one of the youngest planetary surfaces in the Solar System, implying rapid recycling by some mechanism. Despite ubiquitous extension and creation of new surface area at dilational bands that resemble terrestrial mid-ocean spreading zones, there is little evidence of large-scale contraction to balance the observed extension or to recycle ageing terrains. We address this enigma by presenting several lines of evidence that subduction may be recycling surface material into the interior of Europa’s ice shell. Using Galileo spacecraft images, we produce a tectonic reconstruction of geologic features across a 134,000 km2 region of Europa and find, in addition to dilational band spreading, evidence for transform motions along prominent strike-slip faults, as well as the removal of approximately 20,000 km2 of the surface along a discrete tabular zone. We interpret this zone as a subduction-like convergent boundary that abruptly truncates older geological features and is flanked by potential cryolavas on the overriding ice. We propose that Europa’s ice shell has a brittle, mobile, plate-like system above convecting warmer ice. Hence, Europa may be the only Solar System body other than Earth to exhibit a system of plate tectonics.

Effects of hypertrophic and dilated cardiomyopathy mutations on power output by human β-cardiac myosin.

PubMed

Spudich, James A; Aksel, Tural; Bartholomew, Sadie R; Nag, Suman; Kawana, Masataka; Yu, Elizabeth Choe; Sarkar, Saswata S; Sung, Jongmin; Sommese, Ruth F; Sutton, Shirley; Cho, Carol; Adhikari, Arjun S; Taylor, Rebecca; Liu, Chao; Trivedi, Darshan; Ruppel, Kathleen M

2016-01-01

Hypertrophic cardiomyopathy is the most frequently occurring inherited cardiovascular disease, with a prevalence of more than one in 500 individuals worldwide. Genetically acquired dilated cardiomyopathy is a related disease that is less prevalent. Both are caused by mutations in the genes encoding the fundamental force-generating protein machinery of the cardiac muscle sarcomere, including human β-cardiac myosin, the motor protein that powers ventricular contraction. Despite numerous studies, most performed with non-human or non-cardiac myosin, there is no clear consensus about the mechanism of action of these mutations on the function of human β-cardiac myosin. We are using a recombinantly expressed human β-cardiac myosin motor domain along with conventional and new methodologies to characterize the forces and velocities of the mutant myosins compared with wild type. Our studies are extending beyond myosin interactions with pure actin filaments to include the interaction of myosin with regulated actin filaments containing tropomyosin and troponin, the roles of regulatory light chain phosphorylation on the functions of the system, and the possible roles of myosin binding protein-C and titin, important regulatory components of both cardiac and skeletal muscles. © 2016. Published by The Company of Biologists Ltd.

Experimental Pressure Distributions on Axisymmetric Cowls at Mach Numbers From 0.60 to 0.92

NASA Technical Reports Server (NTRS)

Re, Richard J.

2006-01-01

Pressure distributions on four nacelle cowl models of the same length and highlight area but different geometries external to the highlight are compared. The diameter ratio (ratio of highlight diameter to maximum diameter) of the four cowls was 0.854 and the length ratio (ratio of cowl length to maximum diameter) was 0.439. The cowls had the same internal geometry from the highlight to the throat with a contraction ratio (ratio of highlight area to throat area) of 1.250. Data for two other cowls which had a diameter ratio of 0.880, a length ratio of 0.400 and a contraction ratio 1.250 are also included. All the cowls had rows of static pressure orifices on the top and bottom surfaces. Mass-flow ratio was varied between 0.27 and 0.93. Some data were obtained between angles of attack from -2.1deg and 4.1deg. The test was conducted in the Langley 16-Foot Transonic Tunnel.

30 CFR 1206.458 - Determination of washing allowances.

Code of Federal Regulations, 2011 CFR

2011-07-01

... contract. However, before any deduction may be taken, the lessee must submit a completed page one of Form...-arm's-length or no contract situations. However, before any estimated or actual deduction may be taken... allowances specified in paragraphs (c)(1)(v) and (c)(1)(vi) of this section, the lessee shall submit page one...

14 CFR 380.32 - Specific requirements for operator-participant contracts.

Code of Federal Regulations, 2011 CFR

2011-01-01

...) The tour itinerary, if any, including the name and location of the hotels, length of stay at each, and...-departure notification of a major change, the participant may reject the substituted hotel or the changed... the contract, a refund of the portion of his payment allocable to the hotel accommodations or air...

14 CFR 380.32 - Specific requirements for operator-participant contracts.

Code of Federal Regulations, 2010 CFR

2010-01-01

...) The tour itinerary, if any, including the name and location of the hotels, length of stay at each, and...-departure notification of a major change, the participant may reject the substituted hotel or the changed... the contract, a refund of the portion of his payment allocable to the hotel accommodations or air...

The series-elastic shock absorber: tendons attenuate muscle power during eccentric actions

PubMed Central

Azizi, Emanuel

2010-01-01

Elastic tendons can act as muscle power amplifiers or energy-conserving springs during locomotion. We used an in situ muscle-tendon preparation to examine the mechanical function of tendons during lengthening contractions, when muscles absorb energy. Force, length, and power were measured in the lateral gastrocnemius muscle of wild turkeys. Sonomicrometry was used to measure muscle fascicle length independently from muscle-tendon unit (MTU) length, as measured by a muscle lever system (servomotor). A series of ramp stretches of varying velocities was applied to the MTU in fully activated muscles. Fascicle length changes were decoupled from length changes imposed on the MTU by the servomotor. Under most conditions, muscle fascicles shortened on average, while the MTU lengthened. Energy input to the MTU during the fastest lengthenings was −54.4 J/kg, while estimated work input to the muscle fascicles during this period was only −11.24 J/kg. This discrepancy indicates that energy was first absorbed by elastic elements, then released to do work on muscle fascicles after the lengthening phase of the contraction. The temporary storage of energy by elastic elements also resulted in a significant attenuation of power input to the muscle fascicles. At the fastest lengthening rates, peak instantaneous power input to the MTU reached −2,143.9 W/kg, while peak power input to the fascicles was only −557.6 W/kg. These results demonstrate that tendons may act as mechanical buffers by limiting peak muscle forces, lengthening rates, and power inputs during energy-absorbing contractions. PMID:20507964

Right ventricular dilatation on bedside echocardiography performed by emergency physicians aids in the diagnosis of pulmonary embolism.

PubMed

Dresden, Scott; Mitchell, Patricia; Rahimi, Layla; Leo, Megan; Rubin-Smith, Julia; Bibi, Salma; White, Laura; Langlois, Breanne; Sullivan, Alison; Carmody, Kristin

2014-01-01

The objective of this study was to determine the diagnostic performance of right ventricular dilatation identified by emergency physicians on bedside echocardiography in patients with a suspected or confirmed pulmonary embolism. The secondary objective included an exploratory analysis of the predictive value of a subgroup of findings associated with advanced right ventricular dysfunction (right ventricular hypokinesis, paradoxical septal motion, McConnell's sign). This was a prospective observational study using a convenience sample of patients with suspected (moderate to high pretest probability) or confirmed pulmonary embolism. Participants had bedside echocardiography evaluating for right ventricular dilatation (defined as right ventricular to left ventricular ratio greater than 1:1) and right ventricular dysfunction (right ventricular hypokinesis, paradoxical septal motion, or McConnell's sign). The patient's medical records were reviewed for the final reading on all imaging, disposition, hospital length of stay, 30-day inhospital mortality, and discharge diagnosis. Thirty of 146 patients had a pulmonary embolism. Right ventricular dilatation on echocardiography had a sensitivity of 50% (95% confidence interval [CI] 32% to 68%), a specificity of 98% (95% CI 95% to 100%), a positive predictive value of 88% (95% CI 66% to 100%), and a negative predictive value of 88% (95% CI 83% to 94%). Positive and negative likelihood ratios were determined to be 29 (95% CI 6.1% to 64%) and 0.51 (95% CI 0.4% to 0.7%), respectively. Ten of 11 patients with right ventricular hypokinesis had a pulmonary embolism. All 6 patients with McConnell's sign and all 8 patients with paradoxical septal motion had a diagnosis of pulmonary embolism. There was a 96% observed agreement between coinvestigators and principal investigator interpretation of images obtained and recorded. Right ventricular dilatation and right ventricular dysfunction identified on emergency physician performed echocardiography were found to be highly specific for pulmonary embolism but had poor sensitivity. Bedside echocardiography is a useful tool that can be incorporated into the algorithm of patients with a moderate to high pretest probability of pulmonary embolism. Copyright © 2013 American College of Emergency Physicians. Published by Mosby, Inc. All rights reserved.

Method and apparatus for preloading a joint by remotely operable means

NASA Technical Reports Server (NTRS)

Kahn, Jon B. (Inventor)

1993-01-01

The invention is a method and apparatus for joining structures, an active structure and a passive structure, and imposing a tensile pre-load on the joint by a remotely operable mechanism comprising a heat contractible joining element. The method and apparatus include mounting on the structure, a probe shaft of material which is transformable from an expanded length to a contracted length when heated to a specific temperature range. The shaft is provided with a probe head which is receivable in a receptacle opening formed in the passive structure, when the active structure is moved into engagement therewith by an appropriate manipulator mechanism. A latching system mounted on the structure adjacent to the receptacle opening captures the probe head, when the probe head is inserted a predetermined amount. A heating coil on the shaft is energizable by remote control for heating the shaft to a temperature range which transforms the shaft to its contracted length, whereby a latching shoulder thereof engages latching elements of the latching system and imposes a tensile preload on the structural joint. Provision is also made for manually adjusting the probe head on the shaft to allow for manual detachment of the structures or manual preloading of the structural joint.

Method and apparatus for preloading a joint by remotely operable means

NASA Technical Reports Server (NTRS)

Shelton, Robert O. (Inventor)

1992-01-01

The invention is a method and apparatus for joining structures, an active structure and a passive structure, and imposing a tensile pre-load on the joint by a remotely operable mechanism comprising a heat contractible joining element. The method and apparatus include mounting on the structure, a probe shaft of material which is transformable from an expanded length to a contracted length when heated to a specific temperature range. The shaft is provided with a probe head which is receivable in a receptacle opening formed in the passive structure, when the active structure is moved into engagement therewith by an appropriate manipulator mechanism. A latching system mounted on the structure adjacent to the receptacle opening captures the probe head, when the probe head is inserted a predetermined amount. A heating coil on the shaft is energizable by remote control for heating the shaft to a temperature range which transforms the shaft to its contracted length, whereby a latching shoulder thereof engages latching elements of the latching system and imposes a tensile preload on the structural joint. Provision is also made for manually adjusting the probe head on the shaft to allow for manual detachment of the structures or manual preloading of the structural joint.

Investigations on the hierarchy of reference frames in geodesy and geodynamics

NASA Technical Reports Server (NTRS)

Grafarend, E. W.; Mueller, I. I.; Papo, H. B.; Richter, B.

1979-01-01

Problems related to reference directions were investigated. Space and time variant angular parameters are illustrated in hierarchic structures or towers. Using least squares techniques, model towers of triads are presented which allow the formation of linear observation equations. Translational and rotational degrees of freedom (origin and orientation) are discussed along with and the notion of length and scale degrees of freedom. According to the notion of scale parallelism, scale factors with respect to a unit length are given. Three-dimensional geodesy was constructed from the set of three base vectors (gravity, earth-rotation and the ecliptic normal vector). Space and time variations are given with respect to a polar and singular value decomposition or in terms of changes in translation, rotation, deformation (shear, dilatation or angular and scale distortions).

Foam flow and liquid films motion: role of the surfactants properties

NASA Astrophysics Data System (ADS)

Cantat, Isabelle

2011-11-01

Liquid foams absorb energy in a much more efficient way than each of its constituents, taken separately. However, the local process at the origin of the energy dissipation is not entirely elucidated yet, and several models may apply, thus making worth local studies on simpler systems. We investigate the motion through a wet tube of transverse soap films, or lamellae, combining local thickness and velocity measurements in the wetting film. For foaming solution with a high dilatational surface modulus, we reveal a zone of several centimeters in length, the dynamic wetting film, which is significantly influenced by a moving lamella. The dependence of this influence length on lamella velocity and wetting film thickness provides an accurate discrimination among several possible surfactants models. In collaboration with B. Dollet.

Realizing the Translational Potential of Telomere Length Variation as a Tissue-Based Prognostic Marker for Prostate Cancer

DTIC Science & Technology

2015-10-01

Award Number: W81XWH-12-1-0545 TITLE: Realizing the Translational Potential of Telomere Length Variation as a Tissue- Based Prognostic Marker for...COVERED 30Sep2014 - 29Sep2015 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER W81XWH-12-1-0545 Realizing the Translational Potential of Telomere Length...14. ABSTRACT We are testing, in prospective studies from Hopkins (Brady) and Harvard (PHS, HPFS), whether the combination of telomere length

Agarose Gel Electrophoresis Reveals Structural Fluidity of a Phage T3 DNA Packaging Intermediate

PubMed Central

Serwer, Philip; Wright, Elena T.

2012-01-01

We find a new aspect of DNA packaging-associated structural fluidity for phage T3 capsids. The procedure is (1) glutaraldehyde cross-linking of in vivo DNA packaging intermediates for stabilization of structure and then (2) determining of effective radius by two-dimensional agarose gel electrophoresis (2d-AGE). The intermediates are capsids with incompletely packaged DNA (ipDNA) and without an external DNA segment; these intermediates are called ipDNA-capsids. We initially increase production of ipDNA-capsids by raising NaCl concentration during in vivo DNA packaging. By 2d-AGE, we find a new state of contracted shell for some particles of one previously identified ipDNA-capsid. The contracted shell-state is found when ipDNA length/mature DNA length (F) is above 0.17, but not at lower F. Some contracted-shell ipDNA-capsids have the phage tail; others do not. The contracted-shell ipDNA-capsids are explained by premature DNA maturation cleavage that makes accessible a contracted-shell intermediate of a cycle of the T3 DNA packaging motor. The analysis of ipDNA-capsids, rather than intermediates with uncleaved DNA, provides a simplifying strategy for a complete biochemical analysis of in vivo DNA packaging. PMID:22222979

Differential phenotype profile between main right ventricular chamber and outflow tract in chronic pulmonary hypertension: echocardiographic observation.

PubMed

López-Candales, Angel

2014-07-01

Right ventricular (RV) dilatation and systolic dysfunction are known remodeling changes occurring in chronic pulmonary hypertension and are likely the result of increases in pulmonary vascular resistance (PVR). It remains unclear whether PVR affects primarily the main RV chamber (mRVc) or the RV outflow tract (RVOT). Standard echocardiography data were collected from a heterogeneous population of 85 consecutive patients (mean age of 54 ± 12 years and mean pulmonary artery systolic pressure of 56 ± 28 mm Hg) to determine how PVR affected size and function of both RV chambers. Regarding size, PVR correlated more with mRVc end systolic area (r = 0.77; P < 0.0001) than either mRVc end diastolic area (r = 0.58; P < 0.0001) or RVOT systolic length (r = 0.54; P < 0.0001), although it did not correlate with RVOT end diastolic length. In terms of fractional area change, a stronger negative correlation was seen between PVR and mRVc (r = -0.77; P < 0.0001) than with PVR and RVOT (r = -0.69; P < 0.0001). Systolic velocity of the tricuspid annulus was the best parameter in identifying elevated PVR. Based on the echocardiography results, increasing PVR values appear to result in differential RV remodeling with significant mRVc dilation and systolic dysfunction when compared with RVOT. It is important to determine whether the different RV remodeling processes occur in all patients with chronic pulmonary hypertension, regardless of etiology; alter therapeutic response; or determine clinical outcomes.

A review of mixing and propulsion of chyme in the small intestine: fresh insights from new methods.

PubMed

Lentle, R G; de Loubens, C

2015-05-01

The small intestine is a convoluted flexible tube of inconstant form and capacity through which chyme is propelled and mixed by varying patterns of contraction. These inconstancies have prevented quantitative comparisons of the manner in which contractile activity engenders mixing of contained chyme. Recent quantitative work based on spatiotemporal mapping of intestinal contractions, macro- and micro-rheology, particle image velocimetry and real-time modelling has provided new insights into this process. Evidence indicates that the speeds and patterns of the various types of small intestinal contraction are insufficient to secure optimal mixing and enzymatic digestion over a minimal length of intestine. Hence particulate substrates and soluble nutrients become dispersed along the length of the lumen. Mixing within the lumen is not turbulent but results from localised folding and kneading of the contents by contractions but is augmented by the inconstant spatial disposition of the contractions and their component contractile processes. The latter include inconstancies in the sites of commencement and the directions of propagation of contraction in component groups of smooth muscle cells and in the coordination of the radial and circular components of smooth muscle contraction. Evidence suggests there is ongoing augmentation of mixing at the periphery of the lumen, during both the post-prandial and inter-meal periods, to promote flow around and between adjacent villi. This results largely from folding of the relatively inelastic mucosa during repeated radial and longitudinal muscular contraction, causing chyme to be displaced by periodic crowding and separation of the tips of the relatively rigid villi. Further, micro-rheological studies indicate that such peripheral mixing may extend to the apices of enterocytes owing to discontinuities in the mobile mucus layer that covers the ileal mucosa.

Mechanical influences on skeletal muscle vascular tone in humans: insight into contraction-induced rapid vasodilatation

PubMed Central

Kirby, Brett S; Carlson, Rick E; Markwald, Rachel R; Voyles, Wyatt F; Dinenno, Frank A

2007-01-01

We tested the hypothesis that mechanical deformation of forearm blood vessels via acute increases in extravascular pressure elicits rapid vasodilatation in humans. In healthy adults, we measured forearm blood flow (Doppler ultrasound) and calculated forearm vascular conductance (FVC) responses to whole forearm compressions and isometric muscle contractions with the arm above heart level. We used several experimental protocols to gain insight into how mechanical factors contribute to contraction-induced rapid vasodilatation. The findings from the present study clearly indicate that acute increases in extravascular pressure (200 mmHg for 2 s) elicit a significant rapid vasodilatation in the human forearm (peak ΔFVC∼155%). Brief, 6 s sustained compressions evoked the greatest vasodilatation (ΔFVC∼260%), whereas the responses to single (2 s) and repeated compressions (five repeated 2 s compressions) were not significantly different (ΔFVC∼155%versus∼115%, respectively). This mechanically induced vasodilatation peaks within 1–2 cardiac cycles, and thus is dissociated from the temporal pattern normally observed in response to brief muscle contractions (∼4–7 cardiac cycles). A non-linear relation was found between graded increases in extravascular pressure and both the immediate and peak rapid vasodilatory response, such that the responses increased sharply from 25 to 100 mmHg, with no significant further dilatation until 300 mmHg (maximal ΔFVC∼185%). This was in contrast to the linear intensity-dependent relation observed with muscle contractions. Our collective findings indicate that mechanical influences contribute largely to the immediate vasodilatation (first cardiac cycle) observed in response to a brief, single contraction. However, it is clear that there are additional mechanisms related to muscle activation that continue to cause and sustain vasodilatation for several more cardiac cycles after contraction. Additionally, the potential contribution of mechanical influences to the total contraction-induced hyperaemia appears greatest for low to moderate intensity single muscle contractions, and this contribution becomes less significant for sustained and repeated contractions. Nevertheless, this mechanically induced vasodilatation could serve as a feedforward mechanism to increase muscle blood flow at the onset of exercise, as well as in response to changes in contraction intensity, prior to alterations in local vasodilating substances that influence vascular tone. PMID:17495044

Studies of interactions of a propagating shock wave with decaying grid turbulence: velocity and vorticity fields

NASA Astrophysics Data System (ADS)

Agui, Juan H.; Briassulis, George; Andreopoulos, Yiannis

2005-02-01

The unsteady interaction of a moving shock wave with nearly homogeneous and isotropic decaying compressible turbulence has been studied experimentally in a large-scale shock tube facility. Rectangular grids of various mesh sizes were used to generate turbulence with Reynolds numbers based on Taylor's microscale ranging from 260 to 1300. The interaction has been investigated by measuring the three-dimensional velocity and vorticity vectors, the full velocity gradient and rate-of-strain tensors with instrumentation of high temporal and spatial resolution. This allowed estimates of dilatation, compressible dissipation and dilatational stretching to be obtained. The time-dependent signals of enstrophy, vortex stretching/tilting vector and dilatational stretching vector were found to exhibit a rather strong intermittent behaviour which is characterized by high-amplitude bursts with values up to 8 times their r.m.s. within periods of less violent and longer lived events. Several of these bursts are evident in all the signals, suggesting the existence of a dynamical flow phenomenon as a common cause. Fluctuations of all velocity gradients in the longitudinal direction are amplified significantly downstream of the interaction. Fluctuations of the velocity gradients in the lateral directions show no change or a minor reduction through the interaction. Root mean square values of the lateral vorticity components indicate a 25% amplification on average, which appears to be very weakly dependent on the shock strength. The transmission of the longitudinal vorticity fluctuations through the shock appears to be less affected by the interaction than the fluctuations of the lateral components. Non-dissipative vortex tubes and irrotational dissipative motions are more intense in the region downstream of the shock. There is also a significant increase in the number of events with intense rotational and dissipative motions. Integral length scales and Taylor's microscales were reduced after the interaction with the shock in all investigated flow cases. The integral length scales in the lateral direction increase at low Mach numbers and decrease during strong interactions. It appears that in the weakest of the present interactions, turbulent eddies are compressed drastically in the longitudinal direction while their extent in the normal direction remains relatively the same. As the shock strength increases the lateral integral length scales increase while the longitudinal ones decrease. At the strongest interaction of the present flow cases turbulent eddies are compressed in both directions. However, even at the highest Mach number the issue is more complicated since amplification of the lateral scales has been observed in flows with fine grids. Thus the outcome of the interaction strongly depends on the initial conditions.

Wind tunnel investigation of three axisymmetric cowls of different lengths at Mach numbers from 0.60 to 0.92

NASA Technical Reports Server (NTRS)

Re, Richard J.; Abeyounis, William K.

1993-01-01

Pressure distributions on three inlets having different cowl lengths were obtained in the Langley 16-Foot Transonic Tunnel. The cowl diameter ratio (highlight diameter to maximum diameter) was 0.85 and the cowl length ratios (cowl length to maximum diameter) were 0.337, 0.439, and 0.547. The cowls had identical nondimensionalized (with respect to cowl length) external geometry and identical internal geometry. The internal contraction ratio (highlight area to throat area) was 1.250. The inlets had longitudinal rows of static pressure orifices on the top and bottom (external) surfaces and on the contraction (internal) and diffuser surfaces. The afterbody was cylindrical in shape, and its diameter was equal to the maximum diameter of the cowl. Depending on the cowl configuration and free-stream Mach number, the mass-flow ratio varied between 0.27 and 0.87 during the tests. Angle of attack varied from 0 to 4.1 deg at selected Mach numbers and mass-flow ratios, and the Reynolds number varied with the Mach number from 3.2x10(exp 6) to 4.2x10(exp 6) per foot.

Arteriolar insulin resistance in a rat model of polycystic ovary syndrome.

PubMed

Sara, Levente; Antal, Peter; Masszi, Gabriella; Buday, Anna; Horvath, Eszter M; Hamar, Peter; Monos, Emil; Nadasy, Gyorgy L; Varbiro, Szabolcs

2012-02-01

To investigate the vascular dysfunction caused by insulin resistance in polycystic ovary syndrome (PCOS) and the effectiveness of vitamin D in an animal model. Controlled experimental animal study. Animal laboratory at a university research institute. Thirty female Wistar rats. Rats were divided into groups at age 21-28 weeks. Twenty of them were subjected to dihydrotestosterone (DHT) treatment (83 μg/d); ten of them also received parallel vitamin D treatment (120 ng/100 g/wk). Oral glucose tolerance tests with insulin level measurements were performed. Gracilis arterioles were tested for their contractility as well as their nitric oxide (NO)-dependent and insulin-induced dilation using pressure arteriography. Several physiologic parameters, glucose metabolism, and pressure arteriography. DHT treatment increased the passive diameter of resistance arterioles, lowered norepinephrine-induced contraction (30.1 ± 4.7% vs. 8.7 ± 3.6%) and reduced acetylcholine-induced (122.0 ± 2.9% vs. 48.0 ± 1.4%) and insulin-induced (at 30 mU/mL: 21.7 ± 5.3 vs. 9.8 ± 5.6%) dilation. Vitamin D treatment restored insulin relaxation and norepinephrine-induced contractility; in contrast, it failed to alter NO-dependent relaxation. In DHT-treated rats, in addition to metabolically proven insulin resistance, decreased insulin-induced vasorelaxation was observed and was improved by vitamin D treatment without affecting NO-dependent relaxation. The reduction in insulin-induced dilation of arterioles is an important as yet undescribed pathway of vascular damage in PCOS and might explain the clinical effectiveness of vitamin D treatment. Copyright © 2012 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Intraventricular vortex properties in nonischemic dilated cardiomyopathy

PubMed Central

Benito, Yolanda; Alhama, Marta; Yotti, Raquel; Martínez-Legazpi, Pablo; del Villar, Candelas Pérez; Pérez-David, Esther; González-Mansilla, Ana; Santa-Marta, Cristina; Barrio, Alicia; Fernández-Avilés, Francisco; del Álamo, Juan C.

2014-01-01

Vortices may have a role in optimizing the mechanical efficiency and blood mixing of the left ventricle (LV). We aimed to characterize the size, position, circulation, and kinetic energy (KE) of LV main vortex cores in patients with nonischemic dilated cardiomyopathy (NIDCM) and analyze their physiological correlates. We used digital processing of color-Doppler images to study flow evolution in 61 patients with NIDCM and 61 age-matched control subjects. Vortex features showed a characteristic biphasic temporal course during diastole. Because late filling contributed significantly to flow entrainment, vortex KE reached its maximum at the time of the peak A wave, storing 26 ± 20% of total KE delivered by inflow (range: 1–74%). Patients with NIDCM showed larger and stronger vortices than control subjects (circulation: 0.008 ± 0.007 vs. 0.006 ± 0.005 m2/s, respectively, P = 0.02; KE: 7 ± 8 vs. 5 ± 5 mJ/m, P = 0.04), even when corrected for LV size. This helped confining the filling jet in the dilated ventricle. The vortex Reynolds number was also higher in the NIDCM group. By multivariate analysis, vortex KE was related to the KE generated by inflow and to chamber short-axis diameter. In 21 patients studied head to head, Doppler measurements of circulation and KE closely correlated with phase-contract magnetic resonance values (intraclass correlation coefficient = 0.82 and 0.76, respectively). Thus, the biphasic nature of filling determines normal vortex physiology. Vortex formation is exaggerated in patients with NIDCM due to chamber remodeling, and enlarged vortices are helpful for ameliorating convective pressure losses and facilitating transport. These findings can be accurately studied using ultrasound. PMID:24414062

Matrix Metalloproteinases as Regulators of Vein Structure and Function: Implications in Chronic Venous Disease.

PubMed

MacColl, Elisabeth; Khalil, Raouf A

2015-12-01

Lower-extremity veins have efficient wall structure and function and competent valves that permit upward movement of deoxygenated blood toward the heart against hydrostatic venous pressure. Matrix metalloproteinases (MMPs) play an important role in maintaining vein wall structure and function. MMPs are zinc-binding endopeptidases secreted as inactive pro-MMPs by fibroblasts, vascular smooth muscle (VSM), and leukocytes. Pro-MMPs are activated by various activators including other MMPs and proteinases. MMPs cause degradation of extracellular matrix (ECM) proteins such as collagen and elastin, and could have additional effects on the endothelium, as well as VSM cell migration, proliferation, Ca(2+) signaling, and contraction. Increased lower-extremity hydrostatic venous pressure is thought to induce hypoxia-inducible factors and other MMP inducers/activators such as extracellular matrix metalloproteinase inducer, prostanoids, chymase, and hormones, leading to increased MMP expression/activity, ECM degradation, VSM relaxation, and venous dilation. Leukocyte infiltration and inflammation of the vein wall cause further increases in MMPs, vein wall dilation, valve degradation, and different clinical stages of chronic venous disease (CVD), including varicose veins (VVs). VVs are characterized by ECM imbalance, incompetent valves, venous reflux, wall dilation, and tortuosity. VVs often show increased MMP levels, but may show no change or decreased levels, depending on the VV region (atrophic regions with little ECM versus hypertrophic regions with abundant ECM) and MMP form (inactive pro-MMP versus active MMP). Management of VVs includes compression stockings, venotonics, and surgical obliteration or removal. Because these approaches do not treat the causes of VVs, alternative methods are being developed. In addition to endogenous tissue inhibitors of MMPs, synthetic MMP inhibitors have been developed, and their effects in the treatment of VVs need to be examined. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

A predictive model for canine dilated cardiomyopathy-a meta-analysis of Doberman Pinscher data.

PubMed

Simpson, Siobhan; Edwards, Jennifer; Emes, Richard D; Cobb, Malcolm A; Mongan, Nigel P; Rutland, Catrin S

2015-01-01

Dilated cardiomyopathy is a prevalent and often fatal disease in humans and dogs. Indeed dilated cardiomyopathy is the third most common form of cardiac disease in humans, reported to affect approximately 36 individuals per 100,000 individuals. In dogs, dilated cardiomyopathy is the second most common cardiac disease and is most prevalent in the Irish Wolfhound, Doberman Pinscher and Newfoundland breeds. Dilated cardiomyopathy is characterised by ventricular chamber enlargement and systolic dysfunction which often leads to congestive heart failure. Although multiple human loci have been implicated in the pathogenesis of dilated cardiomyopathy, the identified variants are typically associated with rare monogenic forms of dilated cardiomyopathy. The potential for multigenic interactions contributing to human dilated cardiomyopathy remains poorly understood. Consistent with this, several known human dilated cardiomyopathy loci have been excluded as common causes of canine dilated cardiomyopathy, although canine dilated cardiomyopathy resembles the human disease functionally. This suggests additional genetic factors contribute to the dilated cardiomyopathy phenotype.This study represents a meta-analysis of available canine dilated cardiomyopathy genetic datasets with the goal of determining potential multigenic interactions relating the sex chromosome genotype (XX vs. XY) with known dilated cardiomyopathy associated loci on chromosome 5 and the PDK4 gene in the incidence and progression of dilated cardiomyopathy. The results show an interaction between known canine dilated cardiomyopathy loci and an unknown X-linked locus. Our study is the first to test a multigenic contribution to dilated cardiomyopathy and suggest a genetic basis for the known sex-disparity in dilated cardiomyopathy outcomes.

Biodegradable esophageal stent placement does not prevent high-grade stricture formation after circumferential mucosal resection in a porcine model.

PubMed

Pauli, Eric M; Schomisch, Steve J; Furlan, Joseph P; Marks, Andrea S; Chak, Amitabh; Lash, Richard H; Ponsky, Jeffrey L; Marks, Jeffrey M

2012-12-01

Advanced esophageal dysplasia and early cancers have been treated traditionally with esophagectomy. Endoscopic esophageal mucosectomy (EEM) offers less-invasive therapy, but high-degree stricture formation limits its applicability. We hypothesized that placement of a biodegradable stent (BD-stent) immediately after circumferential EEM would prevent stricturing. Ten pigs (five unstented controls, five BD-stent) were utilized. Under anesthesia, a flexible endoscope with a band ligator and snare was used to incise the mucosa approximately 20 cm proximal to the lower esophageal sphincter. A 10-cm, circumferential, mucosal segment was dissected and excised by using snare electrocautery. In the stented group, an 18-×120-mm, self-expanding, woven polydioxanone stent (ELLA-CS, Hradec-Kralove) was deployed. Weekly esophagograms evaluated for percent reduction in esophageal diameter, stricture length, and proximal esophageal dilation. Animals were euthanized when the stricture exceeded 80% and were unable to gain weight (despite high-calorie liquid diet) or at 14 weeks. The control group rapidly developed esophageal strictures; no animal survived beyond the third week of evaluation. At 2 weeks post-EEM, the BD-stent group had a significant reduction in esophageal diameter (77.7 vs. 26.6%, p < 0.001) and degree of proximal dilation (175 vs. 131%, p = 0.04) compared with controls. Survival in the BD-stent group was significantly longer than in the control group (9.2 vs. 2.4 weeks, p = 0.01). However, all BD-stent animals ultimately developed clinically significant strictures (range, 4-14 weeks). Comparison between the maximum reduction in esophageal diameter and stricture length (immediately before euthanasia) demonstrated no differences between the groups. Circumferential EEM results in severe stricture formation and clinical deterioration within 3 weeks. BD-stent placement significantly delays the time of clinical deterioration from 2.4 to 9.2 weeks, but does not affect the maximum reduction in esophageal diameter or proximal esophageal dilatation. The timing of stricture formation in the BD-stent group correlated with the loss radial force and stent disintegration.

The Turning Point for Morphomechanical Remodeling During Complete Intestinal Obstruction in Rats Occurs After 12-24 h.

PubMed

Sun, Daming; Zhao, Jingbo; Liao, Donghua; Huang, Zhiyong; Gregersen, Hans

2018-05-01

Intestinal obstruction prompts luminal dilation and wall remodeling proximal to the site of obstruction. Studies on temporal and spatial morphomechanical remodeling are needed for comprehending the pathophysiology of acute intestinal obstruction. The aim was to estimate the no-load and zero-stress morphomechanical properties in circumferential and longitudinal direction at 0, 6, 12, 24, 36, and 48 h after complete intestinal obstruction. Obstruction of the distal ileum was created surgically by placement of a polyethylene ring for up to 48 h in 30 rats. Sham and normal groups were also studied (n = 12). Five 6 cm-long intestinal segments proximal to the obstruction site were used for histological, morphometric and mechanical analysis at the designated times. Morphomechanical changes were huge but only subtle changes were observed between the 5 segments during the obstruction period. Due to dilation, the serosal length and mucosal length increased continuously from 6 to 48 h (p < 0.001). The wall area increased at 24 h and beyond (p < 0.001), demonstrating tissue growth. The opening and bending angle decreased to minimum values at 24 h where after the opening angle increased and the bending angle returned to pre-obstruction levels. For the residual stretch ratios and the position of the neutral axis the turning point was found after 24 h. Histologically, the thickness and area of most wall layers were quite stable for the first 12 h but with an increase at the 24 h time point that continued to the 48 h time point. The most pronounced change was found for the circumferential muscle layer (p < 0.05). Analysis of picrosirius red stained slides showed that submucosal type 3 collagen fraction increased significantly (p < 0.001), whereas the fraction of type 1 collagen decreased (p < 0.001). In conclusion, pronounced time-dependent morphomechanical remodeling was found. The obstructed intestine went from dilation remodeling to growth remodeling during the interval 12-24 h after creating the obstruction.

Effects of plyometric and isometric training on muscle and tendon stiffness in vivo.

PubMed

Kubo, Keitaro; Ishigaki, Tomonobu; Ikebukuro, Toshihiro

2017-08-01

The purpose of this study was to compare the effects of plyometric and isometric training on tendon properties during ramp and ballistic contractions and muscle stiffness under passive and active conditions. Eleven subjects completed 12 weeks (3 days/week) of a unilateral training program for the plantar flexors. They performed plyometric training on one side (PLY) and isometric training on the other side (ISO). Active muscle stiffness in the medial gastrocnemius muscle was calculated according to changes in estimated muscle force and fascicle length during fast stretching after submaximal isometric contractions. Passive muscle stiffness was also calculated from estimated passive muscle force and fascicle length during slow passive stretching. Stiffness and hysteresis of tendon structures were measured using ultrasonography during ramp and ballistic contractions. Passive muscle stiffness and tendon hysteresis did not change for PLY or ISO Active muscle stiffness significantly increased for PLY, but not for ISO Tendon stiffness during ramp and ballistic contractions increased significantly for ISO, but not for PLY In addition, tendon elongation values at force production levels beyond 100 N during ballistic contractions increased for PLY These results suggest that plyometric training (but not isometric training) enhances the extensibility of tendon structures during ballistic contractions and active muscle stiffness during fast stretching, and these changes may be related to improved performances during stretch-shortening cycle exercises. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

Effect of number and position of intraocular lens haptics on anterior capsule contraction: a randomized, prospective trial.

PubMed

Choi, Mihyun; Lazo, Marjorie Z; Kang, Minji; Lee, Jeehye; Joo, Choun-Ki

2018-03-20

The present study aimed to evaluate the degree of anterior capsule contraction (capsulorhexis contraction) with three different single-piece, hydrophilic acrylic intraocular lenses (IOLs). Patients were prospectively randomized to be implanted with one of three types of IOLs during cataract surgery: the Ophtec Precizon (IOL A), the Lucid Korea Microflex (IOL B), and the Carl Zeiss Asphina (IOL C). One week, 2 weeks, and 6 months after surgery, the area of the anterior capsule opening was measured using digital retro-illumination images after dilation of the pupil. The data were then evaluated using POCOman software. The study included 236 eyes of 202 patients. The area of the anterior capsule opening reduced by 3.53 ± 3.31 mm (17.06% ± 15.99%) between 1 week and 2 months post-operatively in the IOL A group, by 0.62 ± 1.32 mm (2.87% ± 6.03%) in the IOL B group, and by 1.09 ± 1.53 mm (4.72% ± 6.10%) in the IOL C group. The IOL B group showed minimal anterior capsule contraction 2 months after surgery (p < 0.001). IOLs with a four-plate haptic design (IOL B) showed more anterior capsular stability than those with a two-loop plate haptic (IOL A) or two-plate haptic (IOL C) design. The number and position of haptics in a capsular bag may affect anterior capsule contraction. We assume that supporting the zonules evenly may play a role in anterior capsular stability. Current Controlled Trials ISRCTN76566080 , Retrospectively registered (Date of registration: 14 Feb 2018).

Axial Movements and Length Changes of the Human Lower Esophageal Sphincter During Respiration and Distension-induced Secondary Peristalsis Using Functional Luminal Imaging Probe

PubMed Central

Liao, Donghua; Lottrup, Christian; Fynne, Lotte; McMahon, Barry P; Krogh, Klaus; Drewes, Asbjørn M; Zhao, Jingbo; Gregersen, Hans

2018-01-01

Background/Aims Efficient transport through the esophago-gastric junction (EGJ) requires synchronized circular and longitudinal muscle contraction of the esophagus including relaxation of the lower esophageal sphincter (LES). However, there is a scarcity of technology for measuring esophagus movements in the longitudinal (axial) direction. The aim of this study is to develop new analytical tools for dynamic evaluation of the length change and axial movement of the human LES based on the functional luminal imaging probe (FLIP) technology and to present normal signatures for the selected parameters. Methods Six healthy volunteers without hiatal hernia were included. Data were analyzed from stepwise LES distensions at 20, 30, and 40 mL bag volumes. The bag pressure and the diameter change were used for motion analysis in the LES. The cyclic bag pressure frequency was used to distinguish dynamic changes of the LES induced by respiration and secondary peristalsis. Results Cyclic fluctuations of the LES were evoked by respiration and isovolumetric distension, with phasic changes of bag pressure, diameter, length, and axial movement of the LES narrow zone. Compared to the respiration-induced LES fluctuations, peristaltic contractions increased the contraction pressure amplitude (P < 0.001), shortening (P < 0.001), axial movement (P < 0.001), and diameter change (P < 0.01) of the narrow zone. The length of the narrow zone shortened as function of the pressure increase. Conclusions FLIP can be used for evaluation of dynamic length changes and axial movement of the human LES. The method may shed light on abnormal longitudinal muscle activity in esophageal disorders. PMID:29605981

Cyanotic congenital heart disease the coronary arterial circulation.

PubMed

Perloff, Joseph K

2012-02-01

The coronary circulation in cyanotic congenital heart disease (CCHD) includes the extramural coronary arteries, basal coronary blood flow, flow reserve, the coronary microcirculation, and coronary atherogenesis. Coronary arteriograms were analyzed in 59 adults with CCHD. Dilated extramural coronaries were examined histologically in six patients. Basal coronary blood flow was determined with N-13 positron emission tomography in 14 patients and in 10 controls. Hyperemic flow was induced by intravenous dipyridamole pharmacologic stress. Immunostaining against SM alpha-actin permitted microcirculatory morphometric analysis. Non-fasting total cholesterols were retrieved in 279 patients divided into four groups: Group A---143 cyanotic unoperated, Group B---47 rendered acyanotic by reparative surgery, Group C---41 acyanotic unoperated, Group D---48 acyanotic before and after operation. Extramural coronary arteries were mildly or moderately dilated to ectatic in 49/59 angiograms. Histologic examination disclosed loss of medial smooth muscle, increased medial collagen, and duplication of internal elastic lamina. Basal coronary flow was appreciably increased. Hyperemic flow was comparable to controls. Remodeling of the microcirculation was based upon coronary arteriolar length, volume and surface densities. Coronary atherosclerosis was absent in both the arteriograms and the necropsy specimens. Extramural coronary arteries in CCHD dilate in response to endothelial vasodilator substances supplemented by mural attenuation caused by medial abnormalities. Basal coronary flow was appreciably increased, but hyperemic flow was normal. Remodeling of the microcirculation was responsible for preservation of flow reserve. The coronaries were atheroma-free because of the salutory effects of hypocholesterolemia, hypoxemia, upregulated nitric oxide, low platelet counts, and hyperbilirubinrmia.

Urethral Strictures and Stenoses Caused by Prostate Therapy

PubMed Central

Chen, Mang L.; Correa, Andres F.; Santucci, Richard A.

2016-01-01

The number of patients with prostate cancer and benign prostatic hyperplasia is on the rise. As a result, the volume of prostate treatment and treatment-related complications is also increasing. Urethral strictures and stenoses are relatively common complications that require individualized management based on the length and location of the obstruction, and the patient’s overall health, and goals of care. In general, less invasive options such as dilation and urethrotomy are preferred as first-line therapy, followed by more invasive substitution, flap, and anastomotic urethroplasty. PMID:27601967

Influence of particle shape on the microstructure evolution and the mechanical properties of granular materials

NASA Astrophysics Data System (ADS)

Tian, Jianqiu; Liu, Enlong; Jiang, Lian; Jiang, Xiaoqiong; Sun, Yi; Xu, Ran

2018-06-01

In order to study the influence of particle shape on the microstructure evolution and the mechanical properties of granular materials, a two-dimensional DEM analysis of samples with three particle shapes, including circular particles, triangular particles, and elongated particles, is proposed here to simulate the direct shear tests of coarse-grained soils. For the numerical test results, analyses are conducted in terms of particle rotations, fabric evolution, and average path length evolution. A modified Rowe's stress-dilatancy equation is also proposed and successfully fitted onto simulation data.

Muscle structure, sarcomere length and influences on meat quality: A review.

PubMed

Ertbjerg, Per; Puolanne, Eero

2017-10-01

The basic contractile unit of muscle, the sarcomere, will contract as the muscle goes into rigor post-mortem. Depending on the conditions, such as the rate of pH decline, the cooling rate and the mechanical restraints on the muscles, this longitudinal shortening will result in various post-mortem sarcomere lengths as well as lateral differences in the distances between the myosin and actin filaments. This shortening is underlying the phenomena described as rigor contraction, thaw rigor, cold shortening and heat shortening. The shortening in combination with the molecular architecture of the sarcomere as defined by the myosin filaments and their S-1 and S-2 units, the interaction with the actin filaments, and the boundaries formed by the Z-disks will subsequently influence basic meat quality traits including tenderness and water-holding capacity. Biochemical reactions from proteolysis and glycogen metabolism interrelate with the sarcomere length in a complex manner. The sarcomere length is also influencing the eating quality of cooked meat and the water-holding in meat products. Copyright © 2017 Elsevier Ltd. All rights reserved.

Modeling and testing of a knitted-sleeve fluidic artificial muscle

NASA Astrophysics Data System (ADS)

Ball, Erick J.; Meller, Michael A.; Chipka, Jordan B.; Garcia, Ephrahim

2016-11-01

The knitted-sleeve fluidic muscle is similar in design to a traditional McKibben muscle, with a separate bladder and sleeve. However, in place of a braided sleeve, it uses a tubular-knit sleeve made from a thin strand of flexible but inextensible yarn. When the bladder is pressurized, the sleeve expands by letting the loops of fiber slide past each other, changing the dimensions of the rectangular cells in the stitch pattern. Ideally, the internal volume of the sleeve would reach a maximum when its length has contracted by 2/3 from its maximum length, and although this is not reachable in practice, preliminary tests show that free contraction greater than 50% is achievable. The motion relies on using a fiber with a low coefficient of friction in order to reduce hysteresis to an acceptable level. In addition to increased stroke length, potential advantages of this technique include slower force drop-off during the stroke, more useable energy in certain applications, and greater similarity to the force-length relationship of skeletal muscle. Its main limitation is its potentially greater effect from friction compared to other fluidic muscle designs.

Effect of flow and peristaltic mixing on bacterial growth in a gut-like channel

PubMed Central

Cremer, Jonas; Segota, Igor; Yang, Chih-yu; Arnoldini, Markus; Sauls, John T.; Zhang, Zhongge; Gutierrez, Edgar; Groisman, Alex; Hwa, Terence

2016-01-01

The ecology of microbes in the gut has been shown to play important roles in the health of the host. To better understand microbial growth and population dynamics in the proximal colon, the primary region of bacterial growth in the gut, we built and applied a fluidic channel that we call the “minigut.” This is a channel with an array of membrane valves along its length, which allows mimicking active contractions of the colonic wall. Repeated contraction is shown to be crucial in maintaining a steady-state bacterial population in the device despite strong flow along the channel that would otherwise cause bacterial washout. Depending on the flow rate and the frequency of contractions, the bacterial density profile exhibits varying spatial dependencies. For a synthetic cross-feeding community, the species abundance ratio is also strongly affected by mixing and flow along the length of the device. Complex mixing dynamics due to contractions is described well by an effective diffusion term. Bacterial dynamics is captured by a simple reaction–diffusion model without adjustable parameters. Our results suggest that flow and mixing play a major role in shaping the microbiota of the colon. PMID:27681630

Results of Eder-Puestow dilatation in the management of esophageal peptic strictures.

PubMed

Rago, E; Boesby, S; Spencer, J

1983-01-01

Eder-Puestow dilatation of esophageal strictures is a safe procedure. The treatment is followed by symptomatic improvement, but the effect of dilatation on the patients' nutritional state has so far not been reported. We have reviewed 33 patients with benign esophageal stricture with special regard to the effect of dilatation on body weight. A total of 152 dilatations was carried out. All patients had dysphagia, 32 patients had heartburn and 20 had regurgitation. Hiatus hernia was present in 29 patients. Thirteen patients had antireflux surgery; 10 operations were performed before, and four during the dilatation period. One patient required no further dilatations after operation. Dilators greater than 35 FG were passed in 85% of the dilatations. No serious complications occurred. Patients were followed for up to 5 yr (mean follow-up: 27 months). The mean interval between dilatations was 7 months. Body weight was recorded before and one month after dilatation on 78 occasions. There was a significant overall weight increase of 0.78 kg 1 month after dilatation. The mean weight increase was greater after the first dilatation (1.06 kg) than after subsequent ones (0.6 kg). We found that Eder-Puestow dilatation in patients with benign esophageal stricture led to symptomatic improvement and was followed by an increase in body weight.

Balloon dilatation of benign and malignant esophageal strictures. Blind retrograde balloon dilatation.

PubMed

Graham, D Y; Smith, J L

1985-06-01

Balloon esophageal dilatation offers many theoretical advantages (safety, speed, and patient comfort) over dilatation with mercury-filled bougies or with the Eder-Puestow system. The authors used balloon dilators in 22 patients with dysphagia secondary to benign or malignant strictures. Dilatation was performed with fluoroscopic guidance, blindly, or by a combination of these techniques. For "blind" stricture dilatation, an Eder-Puestow spring-tipped guide wire is placed into the stomach using a fiberoptic endoscope. The distance from the incisor teeth to the stricture is measured, and the balloon shaft is marked to indicate when the middle of the balloon is within the stricture. Dilatation is then performed using the antegrade or, the preferred, retrograde technique. Finally, the dilated stricture is calibrated by pulling an inflated balloon through the previously strictured area without difficulty. An attempt was made to achieve an esophageal diameter of 15 mm at the initial dilatation episode, and patient discomfort was used as a guide as to the final diameter. The balloon dilatation technique was highly successful, and a stricture diameter of 15 mm (45-47 French) was achieved at the initial dilatation in most instances. Malignant strictures were easily dilated. Balloon dilatation is convenient, effective, quick, and potentially safer than the previous Eder-Puestow or mercury-filled bougie techniques.

Dilation and Curettage (D&C)

MedlinePlus

... For Patients About ACOG Dilation and Curettage (D&C) Home For Patients Search FAQs Dilation and Curettage ( ... February 2016 PDF Format Dilation and Curettage (D&C) Special Procedures What is dilation and curettage (D& ...

Diagnostic accuracy of maternal anthropometric measurements as predictors for dystocia in nulliparous women

PubMed Central

Alijahan, Rahele; Kordi, Masoumeh; Poorjavad, Munira; Ebrahimzadeh, Saeed

2014-01-01

Background: Dystocia is one of the important causes of maternal morbidity and mortality in low-income countries. This study was aimed to determine the diagnostic accuracy of maternal anthropometric measurements as predictors for dystocia in nulliparous women. Materials and Methods: This prospective cohort study was conducted on 447 nulliparous women who referred to Omolbanin hospital. Several maternal anthropometric measurements such as height, transverse and vertical diameters of Michaelis sacral rhomboid area, foot length, head circumference, vertebral and lower limb length, symphysio-fundal height, and abdominal girth were taken in cervical dilatation ≤ 5 cm. Labor progression was controlled by a researcher blind to these measurements. After delivery, the accuracy of individual and combined measurements in prediction of dystocia was analyzed. Dystocia was defined as cesarean section and vacuum or forceps delivery for abnormal progress of labor (cervical dilatation less than 1 cm/h in the active phase for 2 h, and during the second stage, beyond 2 h or fetal head descend less than 1 cm/h). Results: Among the different anthropometric measurements, transverse diameter of the Michaelis sacral rhomboid area ≤9.6 cm, maternal height ≤ 155 cm, height to symphysio-fundal height ratio ≤4.7, lower limb length ≤78 cm, and head circumference to height ratio ≥ 35.05 with accuracy of 81.2%, 68.2%, 65.5%, 63.3%, and 61.5%, respectively, were better predictors. The best predictor was obtained by combination of maternal height ≤155 cm or the transverse diameter of the Michaelis sacral rhomboid area ≤9.6 cm and Johnson's formula estimated fetal weight ≥3255 g, with an accuracy of 90.5%, sensitivity of 70%, and specificity of 93.7%. Conclusions: Combination of other anthropometric measurements and estimated fetal weight with maternal height in comparison to maternal height alone leads to a better predictor for dystocia. PMID:24554954

Diagnostic accuracy of maternal anthropometric measurements as predictors for dystocia in nulliparous women.

PubMed

Alijahan, Rahele; Kordi, Masoumeh; Poorjavad, Munira; Ebrahimzadeh, Saeed

2014-01-01

Dystocia is one of the important causes of maternal morbidity and mortality in low-income countries. This study was aimed to determine the diagnostic accuracy of maternal anthropometric measurements as predictors for dystocia in nulliparous women. This prospective cohort study was conducted on 447 nulliparous women who referred to Omolbanin hospital. Several maternal anthropometric measurements such as height, transverse and vertical diameters of Michaelis sacral rhomboid area, foot length, head circumference, vertebral and lower limb length, symphysio-fundal height, and abdominal girth were taken in cervical dilatation ≤ 5 cm. Labor progression was controlled by a researcher blind to these measurements. After delivery, the accuracy of individual and combined measurements in prediction of dystocia was analyzed. Dystocia was defined as cesarean section and vacuum or forceps delivery for abnormal progress of labor (cervical dilatation less than 1 cm/h in the active phase for 2 h, and during the second stage, beyond 2 h or fetal head descend less than 1 cm/h). Among the different anthropometric measurements, transverse diameter of the Michaelis sacral rhomboid area ≤9.6 cm, maternal height ≤ 155 cm, height to symphysio-fundal height ratio ≤4.7, lower limb length ≤78 cm, and head circumference to height ratio ≥ 35.05 with accuracy of 81.2%, 68.2%, 65.5%, 63.3%, and 61.5%, respectively, were better predictors. The best predictor was obtained by combination of maternal height ≤155 cm or the transverse diameter of the Michaelis sacral rhomboid area ≤9.6 cm and Johnson's formula estimated fetal weight ≥3255 g, with an accuracy of 90.5%, sensitivity of 70%, and specificity of 93.7%. Combination of other anthropometric measurements and estimated fetal weight with maternal height in comparison to maternal height alone leads to a better predictor for dystocia.

Behavior of human gastrocnemius muscle fascicles during ramped submaximal isometric contractions.

PubMed

Héroux, Martin E; Stubbs, Peter W; Herbert, Robert D

2016-09-01

Precise estimates of muscle architecture are necessary to understand and model muscle mechanics. The primary aim of this study was to estimate continuous changes in fascicle length and pennation angle in human gastrocnemius muscles during ramped plantar flexor contractions at two ankle angles. The secondary aim was to determine whether these changes differ between proximal and distal fascicles. Fifteen healthy subjects performed ramped contractions (0-25% MVC) as ultrasound images were recorded from the medial (MG, eight sites) and lateral (LG, six sites) gastrocnemius muscle with the ankle at 90° and 120° (larger angles correspond to shorter muscle lengths). In all subjects, fascicles progressively shortened with increasing torque. MG fascicles shortened 5.8 mm (11.1%) at 90° and 4.5 mm (12.1%) at 120°, whereas LG muscle fascicles shortened 5.1 mm (8.8%) at both ankle angles. MG pennation angle increased 1.4° at 90° and 4.9° at 120°, and LG pennation angle decreased 0.3° at 90° and increased 2.6° at 120°. Muscle architecture changes were similar in proximal and distal fascicles at both ankle angles. This is the first study to describe continuous changes in fascicle length and pennation angle in the human gastrocnemius muscle during ramped isometric contractions. Very similar changes occurred in proximal and distal muscle regions. These findings are relevant to studies modeling active muscle mechanics. © 2016 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

Effects of fetal hypothyroidism on uterine smooth muscle contraction and structure of offspring rats.

PubMed

Bagheripuor, Fatemeh; Ghanbari, Mahboubeh; Piryaei, Abbas; Ghasemi, Asghar

2018-05-01

What is the central question of this study? Does fetal hypothyroidism in rats alter uterine contractions and structure in the adult offspring? What is the main finding and its importance? Our study indicated that maternal hypothyroidism during pregnancy increased gestational length and decreased litter size. In addition, maternal hypothyroidism caused delayed puberty onset, irregular uterine contractions and histological changes in the uterus in the female offspring. This model might contribute to a better understanding of the cellular and molecular mechanisms involved in uterine contractions in fetal hypothyroidism, studies which are not possible in humans, and might help to establish therapeutic methods for these disorders observed in uterine contractions. Thyroid hormones play an essential role in fetal growth. Hypothyroidism impairs reproductive function in both humans and animals. The aim of this study was to assess the effects of fetal hypothyroidism on uterine smooth muscle contraction and structure in the adult offspring. The control group of female Wistar rats consumed tap water, whereas the hypothyroid group received water containing 0.025% of 6-propyl-2-thiouracial throughout gestation from mating until delivery. Isometric contractility and histological changes in uterine tissue were evaluated in the adult female offspring. We tested the effects of carbachol (10 -10 -10 -3  m) and oxytocin (10 -13 -10 -8  m) on uterine smooth muscle contraction in the fetal hypothyroid (FH) and control groups. Compared with control uteri, carbachol induced contractions with lower amplitude in the FH group (area under the curve: 1820.0 ± 250.0 versus 1370.0 ± 125.0 a.u., control versus FH group, respectively, P < 0.001) and frequency (86.4 ± 7.3 versus 37.0 ± 6.1 a.u., P < 0.001). Likewise, after exposure to oxytocin the amplitude (6614.0 ± 492.2 versus 4793.0 ± 735.2 a.u., P < 0.001) and frequency (367.4 ± 32.0 versus 167.0 ± 39.0 a.u., P < 0.001) of uterine contractions in the FH group were significantly lower than in the control group. In addition, the thickness of the endometrium and smooth muscle layer and the cross-sectional area of the uterus were also significantly lower in the FH group. Gestational length was longer and litter size smaller in FH rats compared with control animals; FH offspring also had delayed puberty. In conclusion, thyroid hormone deficiency during pregnancy increased gestational length and decreased litter size; in the offspring, it delayed puberty onset, reduced uterine rhythmic contractions and resulted in uterine structural changes. © 2018 The Authors. Experimental Physiology © 2018 The Physiological Society.

Cardiomyopathy and response to enzyme replacement therapy in a male mouse model for Fabry disease.

PubMed

Nguyen Dinh Cat, Aurelie; Escoubet, Brigitte; Agrapart, Vincent; Griol-Charhbili, Violaine; Schoeb, Trenton; Feng, Wenguang; Jaimes, Edgar; Warnock, David G; Jaisser, Frederic

2012-01-01

Fabry disease is an X-linked disorder of glycosphingolipid metabolism that results in progressive accumulation of neutral glycosphingolipids, (predominately globotriaosylceramide; GL-3) in lysosomes, as well as other cellular compartments and the extracellular space. Our aim was to characterize the cardiac phenotype of male knock-out mice that are deficient in alpha-galactosidase A activity, as a model for Fabry disease and test the efficacy of Enzyme Replacement Therapy with agalsidase-beta. Male mice (3-4 months of age) were characterized with awake blood pressure and heart rate measurements, cardiac echocardiography and electrocardiography measurements under light anesthesia, histological studies and molecular studies with real-time polymerase chain reaction. The Fabry knock-out mouse has bradycardia and lower blood pressure than control wild type (CB7BL/6J) mice. In Fabry knock-out mice, the cardiomyopathy associated mild hypertrophy at echography with normal systolic LV function and mild diastolic dysfunction. Premature atrial contractions were more frequent in without conduction defect. Heart weight normalized to tibial length was increased in Fabry knock-out mice. Ascending aorta dilatation was observed. Molecular studies were consistent with early stages of cardiac remodeling. A single dose of agalsidase-beta (3 mg/kg) did not affect the LV hypertrophy, function or heart rate, but did improve the mRNA signals of early cardiac remodeling. In conclusion, the alpha-galactosidase A deficient mice at 3 to 4 months of age have cardiac and vascular alterations similar to that described in early clinical stage of Fabry disease in children and adolescents. Enzyme replacement therapy affects cardiac molecular remodeling after a single dose.

Secondary Students' Understanding of Basic Ideas of Special Relativity

NASA Astrophysics Data System (ADS)

Dimitriadi, Kyriaki; Halkia, Krystallia

2012-11-01

A major topic that has marked 'modern physics' is the theory of special relativity (TSR). The present work focuses on the possibility of teaching the basic ideas of the TSR to students at the upper secondary level in such a way that they are able to understand and learn the ideas. Its aim is to investigate students' learning processes towards the two axioms of the theory (the principle of relativity and the invariance of the speed of light) and their consequences (the relativity of simultaneity, time dilation and length contraction). Based on an analysis of physics college textbooks, on a review of the relevant bibliography and on a pilot study, a teaching and learning sequence consisting of five sessions was developed. To collect the data, experimental interviews (the so-called teaching experiment) were used. The teaching experiment may be viewed as a Piagetian clinical interview that is deliberately employed as a teaching and learning situation. The sample consisted of 40 10th grade students (aged 15-16). The data were collected by taping and transcribing the 'interviews', as well as from two open-ended questionnaires filled out by each student, one before and the other after the sessions. Methods of qualitative content analysis were applied. The results show that upper secondary education students are able to cope with the basic ideas of the TSR, but there are some difficulties caused by the following student conceptions: (a) there is an absolute frame of reference, (b) objects have fixed properties and (c) the way events happen is independent of what the observers perceive.

Retroactive Event Determination and Its Relativistic Roots

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

Nelson, Sky E.

Quantum theory limits what we are allowed to say about the 'true' state of a quantum system if that system is unobserved. But special relativity relies fundamentally on a universal assumption about what a light particle is doing at ALL times, regardless of being observed (namely, traveling at speed c relative to any inertial observer). This constitutes a fundamental conceptual gap between the theories. In resolving this impasse we show that the state of a light particle (and hence space and time) is not objective or continuous. Time dilation and length contraction become infinite for a photon, so light hasmore » no 'experience' of event separation in space or time ({Delta}t' = 0, {Delta}x' = 0). The principle of simultaneity is applied between an inertial observer and a light particle, such that the relative speed of the two systems is c, and gamma = infinite/undefined. Although light experiences no separation between events, the Lorentz transform {Delta}t' = {gamma} ({Delta}t-{Delta}Lv/c{sup 2}) implies that the inertial observer experiences a separation between those same events of exactly {Delta}t = {Delta}L/c, a light-like separation. In other words, although light does not 'register' time or space itself, light will always be measured by an inertial observer at a position and time exactly as if it had travelled at speed c continuously through the intervening medium. This fits nicely within the limitations set by quantum mechanics. This result is connected with previous work on retroactive event determination, suggesting the ubiquitous existence of ''synchronicity''.« less

Fundamental Principles of Proper Space Kinematics

NASA Astrophysics Data System (ADS)

Wade, Sean

It is desirable to understand the movement of both matter and energy in the universe based upon fundamental principles of space and time. Time dilation and length contraction are features of Special Relativity derived from the observed constancy of the speed of light. Quantum Mechanics asserts that motion in the universe is probabilistic and not deterministic. While the practicality of these dissimilar theories is well established through widespread application inconsistencies in their marriage persist, marring their utility, and preventing their full expression. After identifying an error in perspective the current theories are tested by modifying logical assumptions to eliminate paradoxical contradictions. Analysis of simultaneous frames of reference leads to a new formulation of space and time that predicts the motion of both kinds of particles. Proper Space is a real, three-dimensional space clocked by proper time that is undergoing a densification at the rate of c. Coordinate transformations to a familiar object space and a mathematical stationary space clarify the counterintuitive aspects of Special Relativity. These symmetries demonstrate that within the local universe stationary observers are a forbidden frame of reference; all is in motion. In lieu of Quantum Mechanics and Uncertainty the use of the imaginary number i is restricted for application to the labeling of mass as either material or immaterial. This material phase difference accounts for both the perceived constant velocity of light and its apparent statistical nature. The application of Proper Space Kinematics will advance more accurate representations of microscopic, oscopic, and cosmological processes and serve as a foundation for further study and reflection thereafter leading to greater insight.

Endoscopic balloon catheter dilatation via retrograde or static technique is safe and effective for cricopharyngeal dysfunction

PubMed Central

Chandrasekhara, Vinay; Koh, Joyce; Lattimer, Lakshmi; Dunbar, Kerry B; Ravich, William J; Clarke, John O

2017-01-01

AIM To evaluate the safety and efficacy of upper esophageal sphincter (UES) dilatation for cricopharyngeal (CP) dysfunction. To determine if: (1) indication for dilatation; or (2) technique of dilatation correlated with symptom improvement. METHODS All balloon dilatations performed at our institution from over a 3-year period were retrospectively analyzed for demographics, indication and dilatation site. All dilatations involving the UES underwent further review to determine efficacy, complications, and factors that predict success. Dilatation technique was separated into static (stationary balloon distention) and retrograde (brusque pull-back of a fully distended balloon across the UES). RESULTS Four hundred and eighty-eight dilatations were reviewed. Thirty-one patients were identified who underwent UES dilatation. Median age was 63 years (range 27-81) and 55% of patients were male. Indications included dysphagia (28 patients), globus sensation with evidence of UES dysfunction (2 patients) and obstruction to echocardiography probe with cricopharyngeal (CP) bar (1 patient). There was evidence of concurrent oropharyngeal dysfunction in 16 patients (52%) and a small Zenker’s diverticula (≤ 2 cm) in 7 patients (23%). Dilator size ranged from 15 mm to 20 mm. Of the 31 patients, 11 had dilatation of other esophageal segments concurrently with UES dilatation and 20 had UES dilatation alone. Follow-up was available for 24 patients for a median of 2.5 mo (interquartile range 1-10 mo), of whom 19 reported symptomatic improvement (79%). For patients undergoing UES dilatation alone, follow-up was available for 15 patients, 12 of whom reported improvement (80%). Nineteen patients underwent retrograde dilatation (84% response) while 5 patients had static dilatation (60% response); however, there was no significant difference in symptom improvement between the techniques (P = 0.5). Successful symptom resolution was also not significantly affected by dilator size, oropharyngeal dysfunction, Zenker’s diverticulum, age or gender (P > 0.05). The only complication noted was uvular edema and a shallow ulcer after static dilatation in one patient, which resolved spontaneously and did not require hospital admission. CONCLUSION UES dilatation with a through-the-scope balloon by either static or retrograde technique is safe and effective for the treatment of dysphagia due to CP dysfunction. To our knowledge, this is the first study evaluating retrograde balloon dilatation of the UES. PMID:28465785

The length-force behavior and operating length range of squid muscle vary as a function of position in the mantle wall.

PubMed

Thompson, Joseph T; Shelton, Ryan M; Kier, William M

2014-06-15

Hollow cylindrical muscular organs are widespread in animals and are effective in providing support for locomotion and movement, yet are subject to significant non-uniformities in circumferential muscle strain. During contraction of the mantle of squid, the circular muscle fibers along the inner (lumen) surface of the mantle experience circumferential strains 1.3 to 1.6 times greater than fibers along the outer surface of the mantle. This transmural gradient of strain may require the circular muscle fibers near the inner and outer surfaces of the mantle to operate in different regions of the length-tension curve during a given mantle contraction cycle. We tested the hypothesis that circular muscle contractile properties vary transmurally in the mantle of the Atlantic longfin squid, Doryteuthis pealeii. We found that both the length-twitch force and length-tetanic force relationships of the obliquely striated, central mitochondria-poor (CMP) circular muscle fibers varied with radial position in the mantle wall. CMP circular fibers near the inner surface of the mantle produced higher force relative to maximum isometric tetanic force, P0, at all points along the ascending limb of the length-tension curve than CMP circular fibers near the outer surface of the mantle. The mean ± s.d. maximum isometric tetanic stresses at L₀ (the preparation length that produced the maximum isometric tetanic force) of 212 ± 105 and 290 ± 166 kN m(-2) for the fibers from the outer and inner surfaces of the mantle, respectively, did not differ significantly (P=0.29). The mean twitch:tetanus ratios for the outer and inner preparations, 0.60 ± 0.085 and 0.58 ± 0.10, respectively, did not differ significantly (P=0.67). The circular fibers did not exhibit length-dependent changes in contraction kinetics when given a twitch stimulus. As the stimulation frequency increased, L₀ was approximately 1.06 times longer than LTW, the mean preparation length that yielded maximum isometric twitch force. Sonomicrometry experiments revealed that the CMP circular muscle fibers operated in vivo primarily along the ascending limb of the length-tension curve. The CMP fibers functioned routinely over muscle lengths at which force output ranged from only 85% to 40% of P₀, and during escape jets from 100% to 30% of P₀. Our work shows that the functional diversity of obliquely striated muscles is much greater than previously recognized. © 2014. Published by The Company of Biologists Ltd.

Comparative proteomic analysis reveals heart toxicity induced by chronic arsenic exposure in rats.

PubMed

Huang, Qingyu; Xi, Guochen; Alamdar, Ambreen; Zhang, Jie; Shen, Heqing

2017-10-01

Arsenic is a widespread metalloid in the environment, which poses a broad spectrum of adverse effects on human health. However, a global view of arsenic-induced heart toxicity is still lacking, and the underlying molecular mechanisms remain unclear. By performing a comparative quantitative proteomic analysis, the present study aims to investigate the alterations of proteome profile in rat heart after long-term exposure to arsenic. As a result, we found that the abundance of 81 proteins were significantly altered by arsenic treatment (35 up-regulated and 46 down-regulated). Among these, 33 proteins were specifically associated with cardiovascular system development and function, including heart development, heart morphology, cardiac contraction and dilation, and other cardiovascular functions. It is further proposed that the aberrant regulation of 14 proteins induced by arsenic would disturb cardiac contraction and relaxation, impair heart morphogenesis and development, and induce thrombosis in rats, which is mediated by the Akt/p38 MAPK signaling pathway. Overall, these findings will augment our knowledge of the involved mechanisms and develop useful biomarkers for cardiotoxicity induced by environmental arsenic exposure. Copyright © 2017 Elsevier Ltd. All rights reserved.

Antarctic Analog for Dilational Bands on Europa

NASA Technical Reports Server (NTRS)

Hurford, T. A.; Brunt, K. M.

2014-01-01

Europa's surface shows signs of extension, which is revealed as lithospheric dilation expressed along ridges, dilational bands and ridged bands. Ridges, the most common tectonic feature on Europa, comprise a central crack flanked by two raised banks a few hundred meters high on each side. Together these three classes may represent a continuum of formation. In Tufts' Dilational Model ridge formation is dominated by daily tidal cycling of a crack, which can be superimposed with regional secular dilation. The two sources of dilation can combine to form the various band morphologies observed. New GPS data along a rift on the Ross Ice Shelf, Antarctica is a suitable Earth analog to test the framework of Tufts' Dilational Model. As predicted by Tufts' Dilational Model, tensile failures in the Ross Ice Shelf exhibit secular dilation, upon which a tidal signal can be seen. From this analog we conclude that Tufts' Dilational Model for Europan ridges and bands may be credible and that the secular dilation is most likely from a regional source and not tidally driven.

Centrin-like filaments in the cytopharyngeal apparatus of the ciliates Nassula and Furgasonia: evidence for a relationship with microtubular structures.

PubMed

Vigues, B; Blanchard, M P; Bouchard, P

1999-01-01

The cytopharyngeal apparatus in the Nassulinid ciliates Nassula and Furgasonia is a highly specialized microtubular/filamentous organelle designed for ingestion of organisms such as filamentous bacteria. From studies on living cells, it was previously shown that this organelle, also called "feeding basket," guides the filamentous bacteria and manipulates them to some extent during the early steps of ingestion. This results in a complex sequence of movements where the basket is successively dilated and constricted in its upper part. Whereas some of these movements (dilation) seem to be intrinsic to the microtubular components of the basket, others (constriction) are believed to be mediated by contractile filamentous structures [Tucker, 1968: J. Cell Sci. 3:493-514]. In this study, we have used antibodies raised against ciliate centrins to demonstrate these proteins by Western blot and immunocytochemical methods in Nassula and Furgasonia. In both ciliates, a 20-kDa centrin immunoanalog was localized in the upper (contractile) part of the cytopharyngeal apparatus. Immunoelectron microscopy revealed that cytopharyngeal centrin is engaged in filamentous material, forming a sphincter-like structure possibly involved in the movements of contraction. Interestingly, physical links were noted between filaments labeled for centrin and cytopharyngeal microtubules. The mechanistic implications of these findings are discussed.

New surgical concepts: nasal tip function.

PubMed

Galli, J J; Zavalla, C A; Vivas, D G; Prado, C; Zanetta, G C

1997-01-01

Since the birth of plastic surgery, rhinoplasty has been an outstanding chapter. Facial balance has been endeavoured with two parameters: size and shape. Now, however, the criterion for harmony has involved two more parameters; position and function. Position is related to other facial elements, such as, upper maxilla, upper lip, forehead, and frontonasal sulcus. Function is important because nasal superficial musculoaponeurotic system (SMAS) muscles are important for Nasal tip movement. To understand this better, we must analyze the nasal SMAS, which consists of primary or intrinsic and secondary or extrinsic muscles. When the extrinsics contract, they allow function of the intrinsics. They are the ala nasalis dilator, the ala nasalis elevator, the tranversus, and the tip depressor. Obvious hypertrophies of the dilator and the elevator has been observed in young athletes. Our method combines conventional, new, and modern aspects. It is conventional because the alar cartilages have been completely freed by intercartilaginous and marginal approaches, and the upper or lower border trimmed according to the case. It is more important to measure how much cartilage is left, than how much is removed. The new aspect is consideration of nasal SMAS to treat short noses that display a tendency to descend with laughter, and the modern aspect is the evaluation of dynamic surgical results, apart from the static.

Maternal inflammatory markers and term labor performance.

PubMed

Cierny, Jill T; Unal, E Ramsey; Flood, Pamela; Rhee, Ka Young; Praktish, Allison; Olson, Tara Hudak; Goetzl, Laura

2014-05-01

We sought to examine the relationship between maternal markers of inflammation and labor performance. A nested cohort study was performed utilizing an established cohort of term nulliparous patients. Maternal blood was collected at the onset of regular, painful contractions in patients undergoing labor induction or at admission in patients with spontaneous labor. Levels of cytokines including interleukin (IL)-1, IL-6, and tumor necrosis factor-α were determined using standard multiplex methodology. Maternal demographic data were collected prospectively. Detailed retrospective chart review was performed to extract data on cervical dilation, effacement, and station during labor. Subjects were excluded if they failed to achieve complete dilation. Mixed effects modeling was used to examine the association between serum cytokine quartiles and labor progress in the latent and active phases. In all, 334 women were included in our analysis. The lowest quartile of IL-6 was associated with slower latent labor (P = .001). In contrast, the highest quartiles of IL-1 and tumor necrosis factor-α were associated with slower active labor (P = .03 and .0002, respectively). Proinflammatory activation is important in labor initiation. However, once active labor is established, excess inflammation can be detrimental to efficient labor progress. These data may explain, in part, the known associations among clinical chorioamnionitis, cesarean delivery, and postpartum hemorrhage. Copyright © 2014 Mosby, Inc. All rights reserved.

Horizontal Contraction of Oceanic Lithosphere Tested Using Azimuths of Transform Faults

NASA Astrophysics Data System (ADS)

Gordon, R. G.; Mishra, J. K.

2012-12-01

A central hypothesis or approximation of plate tectonics is that the plates are rigid, which implies that oceanic lithosphere does not contract horizontally as it cools (hereinafter "no contraction"). An alternative hypothesis is that vertically averaged tensional thermal stress in the competent lithosphere is fully relieved by horizontal thermal contraction (hereinafter "full contraction"). These two hypotheses predict different azimuths for transform faults. We build on prior predictions of horizontal thermal contraction of oceanic lithosphere as a function of age to predict the bias induced in transform-fault azimuths by full contraction for 140 azimuths of transform faults that are globally distributed between 15 plate pairs. Predicted bias increases with the length of adjacent segments of mid-ocean ridges and depends on whether the adjacent ridges are stepped, crenellated, or a combination of the two. All else being equal, the bias decreases with the length of a transform fault and modestly decreases with increasing spreading rate. The value of the bias varies along a transform fault. To correct the observed transform-fault azimuths for the biases, we average the predicted values over the insonified portions of each transform fault. We find the bias to be as large as 2.5°, but more typically is ≤ 1.0°. We test whether correcting for the predicted biases improves the fit to plate motion data. To do so, we determine the sum-squared normalized misfit for various values of γ, which we define to be the fractional multiple of bias predicted for full contraction. γ = 1 corresponds to the full contraction, while γ = 0 corresponds to no contraction. We find that the minimum in sum-squared normalized misfit is obtained for γ = 0.9 ±0.4 (95% confidence limits), which excludes the hypothesis of no contraction, but is consistent with the hypothesis of full contraction. Application of the correction reduces but does not eliminate the longstanding misfit between the azimuth of the Kane transform fault with respect to those of the other North America-Nubia transform faults. We conclude that significant ridge-parallel horizontal thermal contraction occurs in young oceanic lithosphere and that it is accommodated by widening of transform-fault valleys, which causes biases in transform-fault azimuths up to 2.5°.

Anchorage Behaviors of Frictional Tieback Anchors in Silty Sand

NASA Astrophysics Data System (ADS)

Hsu, Shih-Tsung; Hsiao, Wen-Ta; Chen, Ke-Ting; Hu, Wen-Chi; Wu, Ssu-Yi

2017-06-01

Soil anchors are extensively used in geotechnical applications, most commonly serve as tieback walls in deep excavations. To investigate the anchorage mechanisms of this tieback anchor, a constitutive model that considers both strain hardening and softening and volume dilatancy entitled SHASOVOD model, and FLAC3D software are used to perform 3-D numerical analyses. The results from field anchor tests are compared with those calculated by numerical analyses to enhance the applicability of the numerical method. After the calibration, this research carried out the parameter studies by numerical analyses. The numerical results reveal that whether the yield of soil around an anchor develops to ground surface and/or touches the diaphragm wall depending on the overburden depth H and the embedded depth Z of an anchor, this study suggests the minimum overburden and embedded depths to avoid the yield of soils develop to ground surface and/or touch the diaphragm wall. When the embedded depth, overburden depth or fixed length of an anchor increases, the anchorage capacity also increases. Increasing fixed length should be the optimum method to increase the anchorage capacity for fixed length less than 20m. However, when the fixed length of an anchor exceeds 30 m, the increasing rate of anchorage capacity per fixed length decreases, and progressive yield occurs obviously between the fixed length and surrounding soil.

Comprehensive swallowing exercises to treat complicated dysphagia caused by esophageal replacement with colon: A case report.

PubMed

Jiang, Li; Wang, Yujue; Li, Na; Qiu, Weihong; Wu, Huixiang; Huo, Jianshan; Dai, Meng; Yu, Yong; Wan, Guifang; Dou, Zulin; Guo, Weiping

2017-02-01

Surgical procedures for colonic replacement of the esophagus are most commonly associated with anastomotic stricture which cause dysphagia. In this report, we describe a rare case of a patient who demonstrated dysphagia resulting from an anastomotic stricture following esophageal replacement with the colon. All the treatments to dilate the anastomotic stricture were ineffective. To investigate the new treatment strategy for a case with complicated dysphagia, clinical dysphagia evaluations, functional oral intake scale (FOIS), videofluoroscopic swallowing study as well as high-resolution manometry were used to evaluate the swallowing function of the patient before and after treatments. Comprehensive swallowing exercises included the protective airway maneuver, tongue pressure resistance feedback exercise, Masako Maneuver swallowing exercise, and the effortful swallowing exercise. Comprehensive swallowing exercises showed good effect in the patient. The FOIS score increased from level 1 to level 7. The videofluoroscopy digital analysis showed that the pharynx constriction rate was 23% and 50%, before and after treatment, respectively. The data from the high-resolution manometry displayed that: the value of the velopharyngeal pressure peak was 82.8 mmHg before treatment and 156.9 mmHg after treatment; the velopharyngeal contraction duration time was 310 milliseconds before treatment and 525 milliseconds after treatment; the value of the hypopharynx pressure peak was 53.7 mmHg before treatment and 103.2 mmHg after treatment; and the hypopharynx contraction duration time was 390 milliseconds before treatment and 1030 milliseconds after treatment. The swallowing visualization illustrated that a bolus could normally pass through the anastomotic stoma, and the bolus leakage was no longer present. The patient was able to eat various consistencies of food independently, and we were able to remove the jejunum nutrient catheter before discharging the patient. For patients with dysphagia caused by anastomotic stricture following esophageal replacement with colon, the swallowing function can be improved by enhancing the pharyngeal impetus when treatment using esophageal dilation is ineffective.

Diagnostic and Prognostic Value of Long-Axis Strain and Myocardial Contraction Fraction Using Standard Cardiovascular MR Imaging in Patients with Nonischemic Dilated Cardiomyopathies.

PubMed

Arenja, Nisha; Riffel, Johannes H; Fritz, Thomas; André, Florian; Aus dem Siepen, Fabian; Mueller-Hennessen, Matthias; Giannitsis, Evangelos; Katus, Hugo A; Friedrich, Matthias G; Buss, Sebastian J

2017-06-01

Purpose To assess the utility of established functional markers versus two additional functional markers derived from standard cardiovascular magnetic resonance (MR) images for their incremental diagnostic and prognostic information in patients with nonischemic dilated cardiomyopathy (NIDCM). Materials and Methods Approval was obtained from the local ethics committee. MR images from 453 patients with NIDCM and 150 healthy control subjects were included between 2005 and 2013 and were analyzed retrospectively. Myocardial contraction fraction (MCF) was calculated by dividing left ventricular (LV) stroke volume by LV myocardial volume, and long-axis strain (LAS) was calculated from the distances between the epicardial border of the LV apex and the midpoint of a line connecting the origins of the mitral valve leaflets at end systole and end diastole. Receiver operating characteristic curve, Kaplan-Meier method, Cox regression, and classification and regression tree (CART) analyses were performed for diagnostic and prognostic performances. Results LAS (area under the receiver operating characteristic curve [AUC] = 0.93, P < .001) and MCF (AUC = 0.92, P < .001) can be used to discriminate patients with NIDCM from age- and sex-matched control subjects. A total of 97 patients reached the combined end point during a median follow-up of 4.8 years. In multivariate Cox regression analysis, only LV ejection fraction (EF) and LAS independently indicated the combined end point (hazard ratio = 2.8 and 1.9, respectively; P < .001 for both). In a risk stratification approach with classification and regression tree analysis, combined LV EF and LAS cutoff values were used to stratify patients into three risk groups (log-rank test, P < .001). Conclusion Cardiovascular MR-derived MCF and LAS serve as reliable diagnostic and prognostic markers in patients with NIDCM. LAS, as a marker for longitudinal contractile function, is an independent parameter for outcome and offers incremental information beyond LV EF and the presence of myocardial fibrosis. © RSNA, 2017 Online supplemental material is available for this article.

Comprehensive swallowing exercises to treat complicated dysphagia caused by esophageal replacement with colon

PubMed Central

Jiang, Li; Wang, Yujue; Li, Na; Qiu, Weihong; Wu, Huixiang; Huo, Jianshan; Dai, Meng; Yu, Yong; Wan, Guifang; Dou, Zulin; Guo, Weiping

2017-01-01

Abstract Introduction: Surgical procedures for colonic replacement of the esophagus are most commonly associated with anastomotic stricture which cause dysphagia. In this report, we describe a rare case of a patient who demonstrated dysphagia resulting from an anastomotic stricture following esophageal replacement with the colon. All the treatments to dilate the anastomotic stricture were ineffective. To investigate the new treatment strategy for a case with complicated dysphagia, clinical dysphagia evaluations, functional oral intake scale (FOIS), videofluoroscopic swallowing study as well as high-resolution manometry were used to evaluate the swallowing function of the patient before and after treatments. Interventions: Comprehensive swallowing exercises included the protective airway maneuver, tongue pressure resistance feedback exercise, Masako Maneuver swallowing exercise, and the effortful swallowing exercise. Outcomes: Comprehensive swallowing exercises showed good effect in the patient. The FOIS score increased from level 1 to level 7. The videofluoroscopy digital analysis showed that the pharynx constriction rate was 23% and 50%, before and after treatment, respectively. The data from the high-resolution manometry displayed that: the value of the velopharyngeal pressure peak was 82.8 mmHg before treatment and 156.9 mmHg after treatment; the velopharyngeal contraction duration time was 310 milliseconds before treatment and 525 milliseconds after treatment; the value of the hypopharynx pressure peak was 53.7 mmHg before treatment and 103.2 mmHg after treatment; and the hypopharynx contraction duration time was 390 milliseconds before treatment and 1030 milliseconds after treatment. The swallowing visualization illustrated that a bolus could normally pass through the anastomotic stoma, and the bolus leakage was no longer present. The patient was able to eat various consistencies of food independently, and we were able to remove the jejunum nutrient catheter before discharging the patient. Conclusion: For patients with dysphagia caused by anastomotic stricture following esophageal replacement with colon, the swallowing function can be improved by enhancing the pharyngeal impetus when treatment using esophageal dilation is ineffective. PMID:28178125

Does the intercept of the heat-stress relation provide an accurate estimate of cardiac activation heat?

PubMed

Pham, Toan; Tran, Kenneth; Mellor, Kimberley M; Hickey, Anthony; Power, Amelia; Ward, Marie-Louise; Taberner, Andrew; Han, June-Chiew; Loiselle, Denis

2017-07-15

The heat of activation of cardiac muscle reflects the metabolic cost of restoring ionic homeostasis following a contraction. The accuracy of its measurement depends critically on the abolition of crossbridge cycling. We abolished crossbridge activity in isolated rat ventricular trabeculae by use of blebbistatin, an agent that selectively inhibits myosin II ATPase. We found cardiac activation heat to be muscle length independent and to account for 15-20% of total heat production at body temperature. We conclude that it can be accurately estimated at minimal muscle length. Activation heat arises from two sources during the contraction of striated muscle. It reflects the metabolic expenditure associated with Ca 2+ pumping by the sarcoplasmic reticular Ca 2+ -ATPase and Ca 2+ translocation by the Na + /Ca 2+ exchanger coupled to the Na + ,K + -ATPase. In cardiac preparations, investigators are constrained in estimating its magnitude by reducing muscle length to the point where macroscopic twitch force vanishes. But this experimental protocol has been criticised since, at zero force, the observed heat may be contaminated by residual crossbridge cycling activity. To eliminate this concern, the putative thermal contribution from crossbridge cycling activity must be abolished, at least at minimal muscle length. We achieved this using blebbistatin, a selective inhibitor of myosin II ATPase. Using a microcalorimeter, we measured the force production and heat output, as functions of muscle length, of isolated rat trabeculae from both ventricles contracting isometrically at 5 Hz and at 37°C. In the presence of blebbistatin (15 μmol l -1 ), active force was zero but heat output remained constant, at all muscle lengths. Activation heat measured in the presence of blebbistatin was not different from that estimated from the intercept of the heat-stress relation in its absence. We thus reached two conclusions. First, activation heat is independent of muscle length. Second, residual crossbridge heat is negligible at zero active force; hence, the intercept of the cardiac heat-force relation provides an estimate of activation heat uncontaminated by crossbridge cycling. Both results resolve long-standing disputes in the literature. © 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.

Increased Titin Compliance Reduced Length-Dependent Contraction and Slowed Cross-Bridge Kinetics in Skinned Myocardial Strips from Rbm (20ΔRRM) Mice.

PubMed

Pulcastro, Hannah C; Awinda, Peter O; Methawasin, Mei; Granzier, Henk; Dong, Wenji; Tanner, Bertrand C W

2016-01-01

Titin is a giant protein spanning from the Z-disk to the M-band of the cardiac sarcomere. In the I-band titin acts as a molecular spring, contributing to passive mechanical characteristics of the myocardium throughout a heartbeat. RNA Binding Motif Protein 20 (RBM20) is required for normal titin splicing, and its absence or altered function leads to greater expression of a very large, more compliant N2BA titin isoform in Rbm20 homozygous mice (Rbm20 (ΔRRM) ) compared to wild-type mice (WT) that almost exclusively express the stiffer N2B titin isoform. Prior studies using Rbm20 (ΔRRM) animals have shown that increased titin compliance compromises muscle ultrastructure and attenuates the Frank-Starling relationship. Although previous computational simulations of muscle contraction suggested that increasing compliance of the sarcomere slows the rate of tension development and prolongs cross-bridge attachment, none of the reported effects of Rbm20 (ΔRRM) on myocardial function have been attributed to changes in cross-bridge cycling kinetics. To test the relationship between increased sarcomere compliance and cross-bridge kinetics, we used stochastic length-perturbation analysis in Ca(2+)-activated, skinned papillary muscle strips from Rbm20 (ΔRRM) and WT mice. We found increasing titin compliance depressed maximal tension, decreased Ca(2+)-sensitivity of the tension-pCa relationship, and slowed myosin detachment rate in myocardium from Rbm20 (ΔRRM) vs. WT mice. As sarcomere length increased from 1.9 to 2.2 μm, length-dependent activation of contraction was eliminated in the Rbm20 (ΔRRM) myocardium, even though myosin MgADP release rate decreased ~20% to prolong strong cross-bridge binding at longer sarcomere length. These data suggest that increasing N2BA expression may alter cardiac performance in a length-dependent manner, showing greater deficits in tension production and slower cross-bridge kinetics at longer sarcomere length. This study also supports the idea that passive mechanical characteristics of the myocardium influence ensemble cross-bridge behavior and maintenance of tension generation throughout the sarcomere.

Esophageal dilation with metal olives under fiberoptic endoscopic control: a new technic.

PubMed

Mangla, J C; Kothari, T

1980-03-01

Three patients with marked strictures (less than 20 Fr.) of the esophagus are described. It was very difficult to institute any simple program of dilation because mercury-filled Maloney bougies will buckle and rigid endoscopy with dilation carries a great risk of perforation. Using the conventional methods such as Eder-Puestow dilation results in significant waste of time, money and fluoroscopic help. A new technic is described whereby a successful dilation was carried out under direct visual control by endoscopic dilation of the esophagus with Eder-Puestow dilators. Since all these patients require esophagoscopy, the dilation procedure can be done in the same sitting.

How to Obtain the Lorentz Space Contraction Formula for a Moving Rod from Knowledge of the Positions of its Ends at Different Times

ERIC Educational Resources Information Center

Guasti, M. Fernandez; Zagoya, C.

2009-01-01

The Lorentz length contraction for a rod in uniform motion is derived performing two measurements at arbitrary times. Provided that the velocity of the rod is known, this derivation does not require the simultaneous measurement of two events. It thus avoids uncomfortable superluminal relationships. Furthermore, since the observer's simultaneous…

Fully covered self-expanding metallic stent placement for benign refractory esophageal strictures.

PubMed

Kahalekar, Vinit; Gupta, Deepak Trilokinath; Bhatt, Pratin; Shukla, Akash; Bhatia, Shobna

2017-05-01

Treatment options for benign refractory esophageal stricture are limited. We retrospectively analyzed data of 11 patients who underwent fully covered self-expanding metallic stent (FC-SEMS) placement for refractory benign esophageal stricture at our institute. Refractory benign esophageal stricture was defined as inability to dilate a stricture to a diameter of 14 mm after a minimum of five sessions at 2-week intervals or inability to maintain diameter of 14 mm for at least 4 weeks. Eleven patients with refractory benign esophageal stricture (corrosive-6, peptic-3, and post-sclerotherapy-2) underwent FC-SEMS placement. The stent was removed after 4-6 weeks as per manufacturer's recommendation. Patients were followed up for 1 year. Three patients with peptic strictures [length of stricture 2, 3, and 3 cm] and two patients with post-sclerotherapy stricture [length 2 and 1.5 cm] had complete response. Two of 6 patients with corrosive stricture (10 cm, 12 cm) developed recurrence of symptoms within 1 month of stent removal, and two after 2 months (8 cm, 3 cm). One patient with corrosive stricture (6 cm) had recurrence after 6 months, and responded to single session of dilatation. One patient with corrosive stricture was asymptomatic for last 12 months. Four stents were migrated. Four patients developed severe retrosternal pain following stent placement, which was managed with analgesics. There were no serious adverse events after placement of stent and removal of stent. Fully covered SEMS is safe and effective for refractory benign non-corrosive esophageal strictures.

Performance-limiting factors for x-ray free electron laser oscillator as a highly coherent, high spectral purity x-ray source

NASA Astrophysics Data System (ADS)

Park, Gunn Tae

X-ray Free Electron Laser (XFEL) is a light source for coherent X-ray using the radiation from relativistic electrons and interaction between the two. In particular, XFEL oscillator(XFELO) uses optical cavity to repeatedly bring back the radiation to electron beam for the interaction. Its optimal performance, maximum single pass gain and minimum round trip loss, critically depends on cavity optics. In ideal case, the optimal performance would be achieved by the periodic radiation mode maximally overlapping with electron beam while the radiation mode is impinging on curved mirror that gives the radiation the focusing, below critical angle and angular divergence being kept small enough at each crystal for Bragg scattering, which is used for near-normal reflection. In reality, there exist various performance degrading factors in the cavity such as heat load on the crystal surface, misalignments of crystals and mirrors and mirror surface errors. In this thesis, we study via both analytic computation and numerical simulation the optimal design and performance of XFELO cavity in the presence of these factors. In optimal design, we implement asymmetric crystals into cavity to enhance the performance. In general, it has undesirable effect of pulse dilation. We present the configuration that avoids pulse length dilation. Then the effects of misalignments, focal length errors and mirror surface errors are to be evaluated and their tolerances are estimated. In particular, the simulation demonstrates that the effect of mirror surface errors on gain and round trip loss is well-within desired performance of XFELO.

Sarcomere mechanics in striated muscles: from molecules to sarcomeres to cells.

PubMed

Rassier, Dilson E

2017-08-01

Muscle contraction is commonly associated with the cross-bridge and sliding filament theories, which have received strong support from experiments conducted over the years in different laboratories. However, there are studies that cannot be readily explained by the theories, showing 1 ) a plateau of the force-length relation extended beyond optimal filament overlap, and forces produced at long sarcomere lengths that are higher than those predicted by the sliding filament theory; 2 ) passive forces at long sarcomere lengths that can be modulated by activation and Ca 2+ , which changes the force-length relation; and 3 ) an unexplained high force produced during and after stretch of activated muscle fibers. Some of these studies even propose "new theories of contraction." While some of these observations deserve evaluation, many of these studies present data that lack a rigorous control and experiments that cannot be repeated in other laboratories. This article reviews these issues, looking into studies that have used intact and permeabilized fibers, myofibrils, isolated sarcomeres, and half-sarcomeres. A common mechanism associated with sarcomere and half-sarcomere length nonuniformities and a Ca 2+ -induced increase in the stiffness of titin is proposed to explain observations that derive from these studies. Copyright © 2017 the American Physiological Society.

Liquid Engine Design: Effect of Chamber Dimensions on Specific Impulse

NASA Technical Reports Server (NTRS)

Hoggard, Lindsay; Leahy, Joe

2009-01-01

Which assumption of combustion chemistry - frozen or equilibrium - should be used in the prediction of liquid rocket engine performance calculations? Can a correlation be developed for this? A literature search using the LaSSe tool, an online repository of old rocket data and reports, was completed. Test results of NTO/Aerozine-50 and Lox/LH2 subscale and full-scale injector and combustion chamber test results were found and studied for this task. NASA code, Chemical Equilibrium with Applications (CEA) was used to predict engine performance using both chemistry assumptions, defined here. Frozen- composition remains frozen during expansion through the nozzle. Equilibrium- instantaneous chemical equilibrium during nozzle expansion. Chamber parameters were varied to understand what dimensions drive chamber C* and Isp. Contraction Ratio is the ratio of the nozzle throat area to the area of the chamber. L is the length of the chamber. Characteristic chamber length, L*, is the length that the chamber would be if it were a straight tube and had no converging nozzle. Goal: Develop a qualitative and quantitative correlation for performance parameters - Specific Impulse (Isp) and Characteristic Velocity (C*) - as a function of one or more chamber dimensions - Contraction Ratio (CR), Chamber Length (L ) and/or Characteristic Chamber Length (L*). Determine if chamber dimensions can be correlated to frozen or equilibrium chemistry.

Mechanism of thrombin-induced vasodilation in human coronary arterioles.

PubMed

Bosnjak, John J; Terata, Ken; Miura, Hiroto; Sato, Atsushi; Nicolosi, Alfred C; McDonald, Monica; Manthei, Sara A; Saito, Takashi; Hatoum, Ossama A; Gutterman, David D

2003-04-01

Thrombin (Thromb), activated as part of the clotting cascade, dilates conduit arteries through an endothelial pertussis toxin (PTX)-sensitive G-protein receptor and releases nitric oxide (NO). Thromb also acts on downstream microvessels. Therefore, we examined whether Thromb dilates human coronary arterioles (HCA). HCA from right atrial appendages were constricted by 30-50% with endothelin-1. Dilation to Thromb (10(-4)-1 U/ml) was assessed before and after inhibitors with videomicroscopy. There was no tachyphylaxis to Thromb dilation (maximum dilation = 87.0%, ED(50) = 1.49 x 10(-2)). Dilation to Thromb was abolished with either hirudin or denudation but was not affected by PTX. Neither N(omega)-nitro-l-arginine methyl ester (n = 7), indomethacin (n = 9), (1)H-[1,2,4] oxadiazolo-[4,3-a]quinoxalin-1-one (n = 6), tetraethylammonium chloride (n = 5), nor iberiotoxin (n = 4) reduced dilation to Thromb. However, KCl (maximum dilation = 89 +/- 5 vs. 20 +/- 10%; P < 0.05; n = 7), tetrabutylammonium chloride (maximum dilation = 79 +/- 7 vs. 21 +/- 4%; P < 0.05; n = 5), and charybdotoxin (maximum dilation = 89 +/- 4 vs. 10 +/- 2%; P < 0.05; n = 4) attenuated dilation to Thromb. In contrast to animal models, Thromb-induced dilation in human arterioles is independent of G(i)-protein activation and NO release. However, Thromb dilation is endothelium dependent, is maintained on consecutive applications, and involves activation of K(+) channels. We speculate that an endothelium-derived hyperpolarizing factor contributes to Thromb-induced dilation in HCA.

Dynamic equilibration of airway smooth muscle contraction during physiological loading.

PubMed

Latourelle, Jeanne; Fabry, Ben; Fredberg, Jeffrey J

2002-02-01

Airway smooth muscle contraction is the central event in acute airway narrowing in asthma. Most studies of isolated muscle have focused on statically equilibrated contractile states that arise from isometric or isotonic contractions. It has recently been established, however, that muscle length is determined by a dynamically equilibrated state of the muscle in which small tidal stretches associated with the ongoing action of breathing act to perturb the binding of myosin to actin. To further investigate this phenomenon, we describe in this report an experimental method for subjecting isolated muscle to a dynamic microenvironment designed to closely approximate that experienced in vivo. Unlike previous methods that used either time-varying length control, force control, or time-invariant auxotonic loads, this method uses transpulmonary pressure as the controlled variable, with both muscle force and muscle length free to adjust as they would in vivo. The method was implemented by using a servo-controlled lever arm to load activated airway smooth muscle strips with transpulmonary pressure fluctuations of increasing amplitude, simulating the action of breathing. The results are not consistent with classical ideas of airway narrowing, which rest on the assumption of a statically equilibrated contractile state; they are consistent, however, with the theory of perturbed equilibria of myosin binding. This experimental method will allow for quantitative experimental evaluation of factors that were previously outside of experimental control, including sensitivity of muscle length to changes of tidal volume, changes of lung volume, shape of the load characteristic, loss of parenchymal support and inflammatory thickening of airway wall compartments.

Real-time determination of sarcomere length of a single cardiomyocyte during contraction

PubMed Central

Kalda, Mari; Vendelin, Marko

2013-01-01

Sarcomere length of a cardiomyocyte is an important control parameter for physiology studies on a single cell level; for instance, its accurate determination in real time is essential for performing single cardiomyocyte contraction experiments. The aim of this work is to develop an efficient and accurate method for estimating a mean sarcomere length of a contracting cardiomyocyte using microscopy images as an input. The novelty in developed method lies in 1) using unbiased measure of similarities to eliminate systematic errors from conventional autocorrelation function (ACF)-based methods when applied to region of interest of an image, 2) using a semianalytical, seminumerical approach for evaluating the similarity measure to take into account spatial dependence of neighboring image pixels, and 3) using a detrend algorithm to extract the sarcomere striation pattern content from the microscopy images. The developed sarcomere length estimation procedure has superior computational efficiency and estimation accuracy compared with the conventional ACF and spectral analysis-based methods using fast Fourier transform. As shown by analyzing synthetic images with the known periodicity, the estimates obtained by the developed method are more accurate at the subpixel level than ones obtained using ACF analysis. When applied in practice on rat cardiomyocytes, our method was found to be robust to the choice of the region of interest that may 1) include projections of carbon fibers and nucleus, 2) have uneven background, and 3) be slightly disoriented with respect to average direction of sarcomere striation pattern. The developed method is implemented in open-source software. PMID:23255581

Mechanisms of flow and ACh-induced dilation in rat soleus arterioles are altered by hindlimb unweighting

NASA Technical Reports Server (NTRS)

Schrage, William G.; Woodman, Christopher R.; Laughlin, M. Harold

2002-01-01

The purpose of this study was to test the hypothesis that endothelium-dependent dilation (flow-induced dilation and ACh-induced dilation) in rat soleus muscle arterioles is impaired by hindlimb unweighting (HLU). Male Sprague-Dawley rats (approximately 300 g) were exposed to HLU or weight-bearing control (Con) conditions for 14 days. Soleus first-order (1A) and second-order (2A) arterioles were isolated, cannulated, and exposed to step increases in luminal flow at constant pressure. Flow-induced dilation was not impaired by HLU in 1A or 2A arterioles. The cyclooxygenase inhibitor indomethacin (Indo; 50 microM) did not alter flow-induced dilation in 1As or 2As. Inhibition of nitric oxide synthase (NOS) with N(omega)-nitro-L-arginine (L-NNA; 300 microM) reduced flow-induced dilation by 65-70% in Con and HLU 1As. In contrast, L-NNA abolished flow-induced dilation in 2As from Con rats but had no effect in HLU 2As. Combined treatment with L-NNA + Indo reduced tone in 1As and 2As from Con rats, but flow-induced dilation in the presence of L-NNA + Indo was not different from responses without inhibitors in either Con or HLU 1As or 2As. HLU also did not impair ACh-induced dilation (10(-9)-10(-4) M) in soleus 2As. L-NNA reduced ACh-induced dilation by approximately 40% in Con 2As but abolished dilation in HLU 2As. Indo did not alter ACh-induced dilation in Con or HLU 2As, whereas combined treatment with L-NNA + Indo abolished ACh-induced dilation in 2As from both groups. We conclude that flow-induced dilation (1As and 2As) was preserved after 2 wk HLU, but HLU decreased the contribution of NOS in mediating flow-induced dilation and increased the contribution of a NOS- and cyclooxygenase-independent mechanism (possibly endothelium-derived hyperpolarizing factor). In soleus 2As, ACh-induced dilation was preserved after 2-wk HLU but the contribution of NOS in mediating ACh-induced dilation was increased.

Some pharmacological properties of uridine nucleotides

PubMed Central

Smith, M. W.

1964-01-01

Uridine di-, tri- and monophosphates (UDP, UTP and UMP) contracted the goldfish intestine preparation in that order of decreasing potency. Adenosine triphosphate (ATP) sensitized the gut to UTP and UDP but not to UMP. The fluoro-derivatives of UMP and UTP behaved like the unsubstituted nucleotides on the goldfish intestine but the main effect of 6-azaUDP and large amounts of uracil and uridine was to cause a relaxation. Structure-action relationships are discussed on the basis of these findings. UDPglucose and UDPacetylglucosamine each contracted the goldfish intestine but they were 500-times less active than UDP. Other smooth muscle preparations (tortoise jejunum, rat uterus, guinea-pig ileum and the fowl rectal caecum) contracted to UTP and UDP, but large amounts were needed. The cardiovascular effects in rats of UMP, UDP and UTP were complex and mediated mainly through an action on the peripheral blood vessels. In rats treated with phenoxybenzamine, UMP raised the blood pressure while UDP and UTP first lowered then raised the blood pressure. The fall in blood pressure was not abolished by pronethalol or atropine. The uridine phosphates affected the rat isolated heart only under hypoxic conditions. UTP and UDP dilated the blood vessels of the rabbit ear and UTP was six-times more effective than ATP. UTP and UDP were equiactive in increasing the force of beat of the frog isolated heart. UMP also had an effect if large amounts were given. PMID:14190461

Esophageal hypomotility and spastic motor disorders: current diagnosis and treatment.

PubMed

Valdovinos, Miguel A; Zavala-Solares, Monica R; Coss-Adame, Enrique

2014-11-01

Esophageal hypomotility (EH) is characterized by abnormal esophageal peristalsis, either from a reduction or absence of contractions, whereas spastic motor disorders (SMD) are characterized by an increase in the vigor and/or propagation velocity of esophageal body contractions. Their pathophysiology is not clearly known. The reduced excitation of the smooth muscle contraction mediated by cholinergic neurons and the impairment of inhibitory ganglion neuronal function mediated by nitric oxide are likely mechanisms of the peristaltic abnormalities seen in EH and SMD, respectively. Dysphagia and chest pain are the most frequent clinical manifestations for both of these dysfunctions, and gastroesophageal reflux disease (GERD) is commonly associated with these motor disorders. The introduction of high-resolution manometry (HRM) and esophageal pressure topography (EPT) has significantly enhanced the ability to diagnose EH and SMD. Novel EPT metrics in particular the development of the Chicago Classification of esophageal motor disorders has enabled improved characterization of these abnormalities. The first step in the management of EH and SMD is to treat GERD, especially when esophageal testing shows pathologic reflux. Smooth muscle relaxants (nitrates, calcium channel blockers, 5-phosphodiesterase inhibitors) and pain modulators may be useful in the management of dysphagia or pain in SMD. Endoscopic Botox injection and pneumatic dilation are the second-line therapies. Extended myotomy of the esophageal body or peroral endoscopic myotomy (POEM) may be considered in highly selected cases but lack evidence.

Comparison of contraction times of a muscle and its motor units

NASA Technical Reports Server (NTRS)

Eldred, E.; Smith, L.; Edgerton, V. R.

1992-01-01

The twitch contraction time (CT) for each of 13 soleus (SOL) and 13 medial gastrocnemius (MG) muscles was compared with the mean CT from a sample of its motor units (MUs; 356 total) to see if the CT of a whole muscle when tested at its optimal length (Lo) differed systematically from that of its MUs tested at their individual Lo's. The CTs of the whole muscle were significantly longer in the ratio of 1.13. This is consistent with a hypothesis that electrical-field effects result in a more protracted contraction of the individual muscle fiber.

Pupillary efficient lighting system

DOEpatents

Berman, Samuel M.; Jewett, Don L.

1991-01-01

A lighting system having at least two independent lighting subsystems each with a different ratio of scotopic illumination to photopic illumination. The radiant energy in the visible region of the spectrum of the lighting subsystems can be adjusted relative to each other so that the total scotopic illumination of the combined system and the total photopic illumination of the combined system can be varied independently. The dilation or contraction of the pupil of an eye is controlled by the level of scotopic illumination and because the scotopic and photopic illumination can be separately controlled, the system allows the pupil size to be varied independently of the level of photopic illumination. Hence, the vision process can be improved for a given level of photopic illumination.

Structural Turnbuckle Bears Compressive or Tensile Loads

NASA Technical Reports Server (NTRS)

Bateman, W. A.; Lang, C. H.

1985-01-01

Column length adjuster based on turnbuckle principle. Device consists of internally and externally threaded bushing, threaded housing and threaded rod. Housing attached to one part and threaded rod attached to other part of structure. Turning double threaded bushing contracts or extends rod in relation to housing. Once adjusted, bushing secured with jamnuts. Device used for axially loaded members requiring length adjustment during installation.

Cyanotic Congenital Heart Disease The Coronary Arterial Circulation

PubMed Central

Perloff, Joseph K

2012-01-01

Background: The coronary circulation in cyanotic congenital heart disease (CCHD) includes the extramural coronary arteries, basal coronary blood flow, flow reserve, the coronary microcirculation, and coronary atherogenesis. Methods: Coronary arteriograms were analyzed in 59 adults with CCHD. Dilated extramural coronaries were examined histologically in six patients. Basal coronary blood flow was determined with N-13 positron emission tomography in 14 patients and in 10 controls. Hyperemic flow was induced by intravenous dipyridamole pharmacologic stress. Immunostaining against SM alpha-actin permitted microcirculatory morphometric analysis. Non-fasting total cholesterols were retrieved in 279 patients divided into four groups: Group A---143 cyanotic unoperated, Group B---47 rendered acyanotic by reparative surgery, Group C---41 acyanotic unoperated, Group D---48 acyanotic before and after operation. Results: Extramural coronary arteries were mildly or moderately dilated to ectatic in 49/59 angiograms. Histologic examination disclosed loss of medial smooth muscle, increased medial collagen, and duplication of internal elastic lamina. Basal coronary flow was appreciably increased. Hyperemic flow was comparable to controls. Remodeling of the microcirculation was based upon coronary arteriolar length, volume and surface densities. Coronary atherosclerosis was absent in both the arteriograms and the necropsy specimens. Conclusions: Extramural coronary arteries in CCHD dilate in response to endothelial vasodilator substances supplemented by mural attenuation caused by medial abnormalities. Basal coronary flow was appreciably increased, but hyperemic flow was normal. Remodeling of the microcirculation was responsible for preservation of flow reserve. The coronaries were atheroma-free because of the salutory effects of hypocholesterolemia, hypoxemia, upregulated nitric oxide, low platelet counts, and hyperbilirubinrmia. PMID:22845810

Dual-Targeting of AR and Akt Pathways by Berberine in Castration-Resistant Prostate Cancer

DTIC Science & Technology

2013-08-01

Berberine in Castration-Resistant Prostate Cancer PRINCIPAL INVESTIGATOR: Haitao Zhang CONTRACTING ORGANIZATION: Tulane University...COVERED 19 2012-18 2013 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER W81XWH-12-1-0275 Dual-Targeting of AR and Akt Pathways by Berberine in Castration...NOTES 14. ABSTRACT We have previously shown berberine , a natural compound, downregulates full-length androgen receptor (AR) and AR splice

A Comparison of Intrathecal and Epidural Analgesia and Its Effect on Length of Labor

DTIC Science & Technology

1997-09-10

time of delivery (Chestnut, Vandewalker, Owen, Bates, & Choi, 1987 ). Epidural or intiathecal injection of opioids has the potential to provide selective...exists pertaining to this issue (Miller, DeVore, & Eisler , 1993). Selective opioid analgesia whether epidural or intrathecal has also resulted in...of contraction of the utems and the pressure generated by these contractions (Miller, DeVore, & Eisler , 1993). Progress of labor: Increasing

Muscle force loss and soreness subsequent to maximal eccentric contractions depend on the amount of fascicle strain in vivo.

PubMed

Guilhem, G; Doguet, V; Hauraix, H; Lacourpaille, L; Jubeau, M; Nordez, A; Dorel, S

2016-06-01

Defining the origins of muscle injury has important rehabilitation and exercise applications. However, current knowledge of muscle damage mechanics in human remains unclear in vivo. This study aimed to determine the relationships between muscle-tendon unit mechanics during maximal eccentric contractions and the extent of subsequent functional impairments induced by muscle damage. The length of the muscle-tendon unit, fascicles and tendinous tissues was continuously measured on the gastrocnemius medialis using ultrasonography, in time with torque, during 10 sets of 30 maximal eccentric contractions of plantar flexors at 45°s(-1) , in seventeen participants. Muscle-tendon unit, fascicles and tendinous tissues were stretched up to 4.44 ± 0.33 cm, 2.31 ± 0.64 cm and 1.92 ± 0.61 cm respectively. Fascicle stretch length, lengthening amplitude and negative fascicle work beyond slack length were significantly correlated with the force decrease 48 h post-exercise (r = 0.51, 0.47 and 0.68, respectively; P < 0.05). This study demonstrates that the strain applied to human muscle fibres during eccentric contractions strongly influences the magnitude of muscle damage in vivo. Achilles tendon compliance decreases the amount of strain, while architectural gear ratio may moderately contribute to attenuating muscle fascicle lengthening and hence muscle damage. Further studies are necessary to explore the impact of various types of task to fully understand the contribution of muscle-tendon interactions during active lengthening to muscle damage. © 2016 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

Sensory-motor responses to mechanical stimulation of the esophagus after sensitization with acid.

PubMed

Drewes, Asbjørn-Mohr; Reddy, Hariprasad; Staahl, Camilla; Pedersen, Jan; Funch-Jensen, Peter; Arendt-Nielsen, Lars; Gregersen, Hans

2005-07-28

Sensitization most likely plays an important role in chronic pain disorders, and such sensitization can be mimicked by experimental acid perfusion of the esophagus. The current study systematically investigated the sensory and motor responses of the esophagus to controlled mechanical stimuli before and after sensitization. Thirty healthy subjects were included. Distension of the distal esophagus with a balloon was performed before and after perfusion with 0.1 mol/L hydrochloric acid for 30 min. An impedance planimetry system was used to measure cross-sectional area, volume, pressure, and tension during the distensions. A new model allowed evaluation of the phasic contractions by the tension during contractions as a function of the initial muscle length before the contraction (comparable to the Frank-Starling law for the heart). Length-tension diagrams were used to evaluate the muscle tone before and after relaxation of the smooth muscle with butylscopolamine. The sensitization resulted in allodynia and hyperalgesia to the distension volumes, and the degree of sensitization was related to the infused volume of acid. Furthermore, a nearly 50% increase in the evoked referred pain was seen after sensitization. The mechanical analysis demonstrated hyper-reactivity of the esophagus following acid perfusion, with an increased number and force of the phasic contractions, but the muscle tone did not change. Acid perfusion of the esophagus sensitizes the sensory pathways and facilitates secondary contractions. The new model can be used to study abnormal sensory-motor mechanisms in visceral organs.

Sensory-motor responses to mechanical stimulation of the esophagus after sensitization with acid

PubMed Central

Drewes, Asbjorn Mohr; Reddy, Hariprasad; Staahl, Camilla; Pedersen, Jan; Funch-Jensen, Peter; Arendt-Nielsen, Lars; Gregersen, Hans

2005-01-01

AIM: Sensitization most likely plays an important role in chronic pain disorders, and such sensitization can be mimicked by experimental acid perfusion of the esophagus. The current study systematically investigated the sensory and motor responses of the esophagus to controlled mechanical stimuli before and after sensitization. METHODS: Thirty healthy subjects were included. Distension of the distal esophagus with a balloon was performed before and after perfusion with 0.1 mol/L hydrochloric acid for 30 min. An impedance planimetry system was used to measure cross-sectional area, volume, pressure, and tension during the distensions. A new model allowed evaluation of the phasic contractions by the tension during contractions as a function of the initial muscle length before the contraction (comparable to the Frank-Starling law for the heart). Length-tension diagrams were used to evaluate the muscle tone before and after relaxation of the smooth muscle with butylscopolamine. RESULTS: The sensitization resulted in allodynia and hyperalgesia to the distension volumes, and the degree of sensitization was related to the infused volume of acid. Furthermore, a nearly 50% increase in the evoked referred pain was seen after sensitization. The mechanical analysis demonstrated hyper-reactivity of the esophagus following acid perfusion, with an increased number and force of the phasic contractions, but the muscle tone did not change. CONCLUSION: Acid perfusion of the esophagus sensitizes the sensory pathways and facilitates secondary contractions. The new model can be used to study abnormal sensory-motor mechanisms in visceral organs. PMID:16038036

Acoustic Experiment to Measure the Bulk Viscosity of Near-Critical Xenon in Microgravity

NASA Technical Reports Server (NTRS)

Gillis, K. A.; Shinder, I.; Moldover, M. R.; Zimmerli, G. A.

2002-01-01

We plan a rigorous test of the theory of dynamic scaling by accurately measuring the bulk viscosity of xenon in microgravity 50 times closer to the critical temperature T(sub c) than previous experiments. The bulk viscosity zeta (or "second viscosity" or "dilational viscosity") will be determined by measuring the attenuation length of sound alpha lambda and also measuring the frequency-dependence of the speed of sound. For these measurements, we developed a unique Helmholtz resonator and specialized electro-acoustic transducers. We describe the resonator, the transducers, their performance on Earth, and their expected performance in microgravity.

Dilations of anastomotic strictures over time after repair of esophageal atresia.

PubMed

Stenström, Pernilla; Anderberg, Magnus; Börjesson, Anna; Arnbjörnsson, Einar

2017-02-01

Anastomotic strictures commonly occur in patients undergoing surgery for esophageal atresia (EA). The primary aim of this study was to determine the age distribution of dilation procedures for anastomotic strictures over the patient's childhood after reconstruction of EA. The secondary aim was to evaluate the effect of postoperative proton pump inhibitors (PPIs) on the frequency of dilations. This observational study was conducted at a single tertiary center of pediatric surgery. The times that dilations of strictures were performed were assessed during three study periods: 1983-1995, 2001-2009, and 2010-2014. PPIs were not used during the first period, and then, respectively, for 3 and 12 months postoperatively. The indications for dilation were signs of obstruction and/or radiological signs of stricture. A total of 131 children underwent esophageal reconstruction, and of those, 60 (46%) required at least 1 dilation procedure for strictures. There were no differences in the frequencies of dilation procedures between the three study periods (28/66, 18/32 and 14/33, respectively; P = 0.42). The overall median number of dilations per patient was 3 (range 1-21) with no differences between the study periods. The differences between ages at which the first dilation was performed during each study period were significant, as follows: 7, 2, and 8 months, respectively (P = 0.03). Fiftyone percent of all dilation procedures were performed during the first year of life, 16% during the second year, and 33% during years 2-15. Four children (2%) underwent >12 dilations. The first year of life was the time of greatest need for dilation of AS after reconstruction of EA; however, dilations were also performed several years later. PPIs did not affect the frequency of dilations during the first year of life.

Eccentric Torque-Producing Capacity is Influenced by Muscle Length in Older Healthy Adults.

PubMed

Melo, Ruth C; Takahashi, Anielle C M; Quitério, Robison J; Salvini, Tânia F; Catai, Aparecida M

2016-01-01

Considering the importance of muscle strength to functional capacity in the elderly, the study investigated the effects of age on isokinetic performance and torque production as a function of muscle length. Eleven younger (24.2 ± 2.9 years) and 16 older men (62.7 ± 2.5 years) were subjected to concentric and eccentric isokinetic knee extension/flexion at 60 and 120° · s(-1) through a functional range of motion. The older group presented lower peak torque (in newton-meters) than the young group for both isokinetic contraction types (age effect, p < 0.001). Peak torque deficits in the older group were near 30 and 29% for concentric and eccentric contraction, respectively. Concentric peak torque was lower at 120° · s(-1) than at 60° · s(-1) for both groups (angular velocity effect, p < 0.001). Eccentric knee extension torque was the only exercise tested that showed an interaction effect between age and muscle length (p < 0.001), which suggested different torque responses to the muscle length between groups. Compared with the young group, the eccentric knee extension torque was 22-56% lower in the older group, with the deficits being lower in the shortened muscle length (22-27%) and higher (33-56%) in the stretched muscle length. In older men, the production of eccentric knee strength seems to be dependent on the muscle length. At more stretched positions, older subjects lose the capacity to generate eccentric knee extension torque. More studies are needed to assess the mechanisms involved in eccentric strength preservation with aging and its relationship with muscle length.

Ventricular flow dynamics with varying LVAD inflow cannula lengths: In-silico evaluation in a multiscale model.

PubMed

Liao, Sam; Neidlin, Michael; Li, Zhiyong; Simpson, Benjamin; Gregory, Shaun D

2018-04-27

Left ventricular assist devices are associated with thromboembolic events, which are potentially caused by altered intraventricular flow. Due to patient variability, differences in apical wall thickness affects cannula insertion lengths, potentially promoting unfavourable intraventricular flow patterns which are thought to be correlated to the risk of thrombosis. This study aimed to present a 3D multiscale computational fluid dynamic model of the left ventricle (LV) developed using a commercial software, Ansys, and evaluate the risk of thrombosis with varying inflow cannula insertion lengths in a severely dilated LV. Based on a HeartWare HVAD inflow cannula, insertion lengths of 5, 19, 24 and 50 mm represented cases of apical hypertrophy, typical ranges of apical thicknesses and an experimental length, respectively. The risk of thrombosis was evaluated based on blood washout, residence time, instantaneous blood stagnation and a pulsatility index. By introducing fresh blood to displace pre-existing blood in the LV, after 5 cardiac cycles, 46.7%, 45.7%, 45.1% and 41.8% of pre-existing blood remained for insertion lengths of 5, 19, 24 and 50 mm, respectively. Compared to the 50 mm insertion, blood residence time was at least 9%, 7% and 6% higher with the 5, 19 and 24 mm insertion lengths, respectively. No instantaneous stagnation at the apex was observed directly after the E-wave. Pulsatility indices adjacent to the cannula increased with shorter insertion lengths. For the specific scenario studied, a longer insertion length, relative to LV size, may be advantageous to minimise thrombosis by increasing LV washout and reducing blood residence time. Copyright © 2018 Elsevier Ltd. All rights reserved.

The Enright phenomenon. Stereoscopic distortion of perceived driving speed induced by monocular pupil dilation.

PubMed

Carkeet, Andrew; Wood, Joanne M; McNeill, Kylie M; McNeill, Hamish J; James, Joanna A; Holder, Leigh S

The Enright phenomenon describes the distortion in speed perception experienced by an observer looking sideways from a moving vehicle when viewing with interocular differences in retinal image brightness, usually induced by neutral density filters. We investigated whether the Enright phenomenon could be induced with monocular pupil dilation using tropicamide. We tested 17 visually normal young adults on a closed road driving circuit. Participants were asked to travel at Goal Speeds of 40km/h and 60km/h while looking sideways from the vehicle with: (i) both eyes with undilated pupils; (ii) both eyes with dilated pupils; (iii) with the leading eye only dilated; and (iv) the trailing eye only dilated. For each condition we recorded actual driving speed. With the pupil of the leading eye dilated participants drove significantly faster (by an average of 3.8km/h) than with both eyes dilated (p=0.02); with the trailing eye dilated participants drove significantly slower (by an average of 3.2km/h) than with both eyes dilated (p<0.001). The speed, with the leading eye dilated, was faster by an average of 7km/h than with the trailing eye dilated (p<0.001). There was no significant difference between driving speeds when viewing with both eyes either dilated or undilated (p=0.322). Our results are the first to show a measurable change in driving behaviour following monocular pupil dilation and support predictions based on the Enright phenomenon. Copyright © 2016 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.

Intermittent dysphagia for solids associated with a multiringed esophagus: clinical features and response to dilatation.

PubMed

Lee, Greta Shao-Chu; Craig, Philip Ian; Freiman, John Saul; de Carle, David; Cook, Ian James

2007-01-01

The entity of the multiringed esophagus, generally presenting in adults as intermittent dysphagia for solids, is relatively uncommon and its pathogenesis is unknown. The goal of this study was to describe the demographic, clinical, and endoscopic features of patients presenting with this condition, their response to esophageal dilatation, and the relationship of multiple esophageal rings to eosinophilic esophagitis. Between 1989 and June 2004, 32 patients at this adult hospital fulfilled the following inclusion criteria: (1) intermittent dysphagia for solids, (2) multiple esophageal rings at endoscopy, and (3) esophageal dilatation(s) performed. Response to esophageal dilatation was measured by need for subsequent dilatations. Seventy-five percent of the patients were male. Median age at onset of dysphagia was 21 years and at presentation 36.5 years. All had multiple rings in the proximal or midesophagus on endoscopy and had undergone a total of 73 esophageal dilatations with no esophageal perforations. Median maximal dilator size was 15 mm; however, 16% developed significant esophageal mucosal tears even with 11-mm dilators. Sixty-six percent required repeat dilatation, with the median time interval before recurrence being 8 months. Eosinophilic esophagitis (mucosal eosinophil count > 20/HPF) was present in 50% of this cohort. From this study we conclude that a multiringed esophagus causing intermittent dysphagia occurs predominantly in young males, responds well to dilatation, but repeated dilatations are often necessary. Dilatation can lead to extensive mucosal tears and should be performed with caution. Eosinophilic esophagitis is commonly but not invariably associated with this entity. Frequent relapse of dysphagia highlights the need for effective pharmacotherapy.

Endoscopic electrocautery dilation of benign anastomotic colonic strictures: a single-center experience.

PubMed

Bravi, Ivana; Ravizza, Davide; Fiori, Giancarla; Tamayo, Darina; Trovato, Cristina; De Roberto, Giuseppe; Genco, Chiara; Crosta, Cristiano

2016-01-01

Benign anastomotic colonic stenosis sometimes occur after surgery and usually require surgical or endoscopic dilation. Endoscopic dilation of anastomotic colonic strictures by using balloon or bougie-type dilators has been demonstrated to be safe and effective in multiple uncontrolled series. However, few data are available on safety and efficacy of endoscopic electrocautery dilation. The aim of our study was to retrospectively investigate safety and efficacy of endoscopic electrocautery dilation of postsurgical benign anastomotic colonic strictures. Sixty patients (37 women; median age 63.6 years, range 22.6-81.7) with benign anastomotic colonic or rectal strictures treated with endoscopic electrocautery dilation between June 2001 and February 2013 were included in the study. Anastomotic stricture was defined as a narrowed anastomosis through which a standard colonoscope could not be passed. Only annular anastomotic strictures were considered suitable for electrocautery dilation which consisted of radial incisions performed with a precut sphincterotome. Treatment was considered successful if the colonic anastomosis could be passed by a standard colonoscope immediately after dilation. Recurrence was defined as anastomotic stricture reappearance during follow-up. The time interval between colorectal surgery and the first endoscopic evaluation or symptoms development was 7.3 months (1.3-60.7). Electrocautery dilation was successful in all the patients. There were no procedure-related complications. Median follow-up was 35.5 months (2.0-144.0). Anastomotic stricture recurrence was observed in three patients who were successfully treated with electrocautery dilation and Savary dilation. Endoscopic electrocautery dilation is a safe and effective treatment for annular benign anastomotic postsurgical colonic strictures.

Development of shape memory metal as the actuator of a fail safe mechanism

NASA Technical Reports Server (NTRS)

Ford, V. G.; Johnson, M. R.; Orlosky, S. D.

1990-01-01

A small, compact, lightweight device was developed using shape memory alloy (SMA) in wire form to actuate a pin-puller that decouples the flanges of two shafts. When the SMA is heated it contracts producing a useful force and stroke. As it cools, it can be reset (elongated in this case) by applying a relatively small force. Resistive heating is accomplished by running a current through the SMA wire for a controlled length of time. The electronics to drive the device are not elaborate or complicated, consisting of a timed current source. The total available contraction is 3 percent of the length of the wire. This device, the engineering properties of the SMA, and the tests performed to verify the design concept are described.

Altered calcium handling and increased contraction force in human embryonic stem cell derived cardiomyocytes following short term dexamethasone exposure

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

Kosmidis, Georgios; Bellin, Milena; Ribeiro, Marcelo C.

One limitation in using human pluripotent stem cell derived cardiomyocytes (hPSC-CMs) for disease modeling and cardiac safety pharmacology is their immature functional phenotype compared with adult cardiomyocytes. Here, we report that treatment of human embryonic stem cell derived cardiomyocytes (hESC-CMs) with dexamethasone, a synthetic glucocorticoid, activated glucocorticoid signaling which in turn improved their calcium handling properties and contractility. L-type calcium current and action potential properties were not affected by dexamethasone but significantly faster calcium decay, increased forces of contraction and sarcomeric lengths, were observed in hESC-CMs after dexamethasone exposure. Activating the glucocorticoid pathway can thus contribute to mediating hPSC-CMs maturation.more » - Highlights: • Dexamethasone accelerates Ca{sup 2+} transient decay in hESC-CMs. • Dexamethasone enhances SERCA and NCX function in hESC-CMs. • Dexamethasone increases force of contraction and sarcomere length in hESC-CMs. • Dexamethasone does not alter I{sub Ca,L} and action potential characteristics in hESC-CMs.« less

Distinct contractile and molecular differences between two goat models of atrial dysfunction: AV block-induced atrial dilatation and atrial fibrillation.

PubMed

Greiser, Maura; Neuberger, Hans-Ruprecht; Harks, Erik; El-Armouche, Ali; Boknik, Peter; de Haan, Sunniva; Verheyen, Fons; Verheule, Sander; Schmitz, Wilhelm; Ravens, Ursula; Nattel, Stanley; Allessie, Maurits A; Dobrev, Dobromir; Schotten, Ulrich

2009-03-01

Atrial dilatation is an independent risk factor for thromboembolism in patients with and without atrial fibrillation (AF). In many patients, atrial dilatation goes along with depressed contractile function of the dilated atria. While some mechanisms causing atrial contractile dysfunction in fibrillating atria have been addressed previously, the cellular and molecular mechanisms of atrial contractile remodeling in dilated atria are unknown. This study characterized in vivo atrial contractile function in a goat model of atrial dilatation and compared it to a goat model of AF. Differences in the underlying mechanisms were elucidated by studying contractile function, electrophysiology and sarcoplasmic reticulum (SR) Ca2+ load in atrial muscle bundles and by analyzing expression and phosphorylation levels of key Ca2+-handling proteins, myofilaments and the expression and activity of their upstream regulators. In 7 chronically instrumented, awake goats atrial contractile dysfunction was monitored during 3 weeks of progressive atrial dilatation after AV-node ablation (AV block goats (AVB)). In open chest experiments atrial work index (AWI) and refractoriness were measured (10 goats with AVB, 5 goats with ten days of AF induced by repetitive atrial burst pacing (AF), 10 controls). Isometric force of contraction (FC), transmembrane action potentials (APs) and rapid cooling contractures (RCC, a measure of SR Ca2+ load) were studied in right atrial muscle bundles. Total and phosphorylated Ca2+-handling and myofilament protein levels were quantified by Western blot. In AVB goats, atrial size increased by 18% (from 26.6+/-4.4 to 31.6+/-5.5 mm, n=7 p<0.01) while atrial fractional shortening (AFS) decreased (from 18.4+/-1.7 to 12.8+/-4.0% at 400 ms, n=7, p<0.01). In open chest experiments, AWI was reduced in AVB and in AF goats compared to controls (at 400 ms: 8.4+/-0.9, n=7, and 3.2+/-1.8, n=5, vs 18.9+/-5.3 mmxmmHg, n=7, respectively, p<0.05 vs control). FC of isolated right atrial muscle bundles was reduced in AVB (n=8) and in AF (n=5) goats compared to controls (n=9) (at 2 Hz: 2.3+/-0.5 and 0.7+/-0.2 vs 5.5+/-1.0 mN/mm2, respectively, p<0.05). APs were shorter in AF, but unchanged in AVB goats. RCCs were reduced in AVB and AF versus control (AVB, 3.4+/-0.5 and AF, 4.1+/-1.4 vs 12.2+/-3.2 mN/mm2, p<0.05). Protein levels of protein kinase A (PKA) phosphorylated phospholamban (PLB) were reduced in AVB (n=8) and AF (n=8) vs control (n=7) by 37.9+/-12.4% and 29.7+/-10.1%, respectively (p<0.01), whereas calmodulin-dependent protein kinase II (CaMKII) phosphorylated ryanodine channels (RyR2) were increased by 166+/-55% in AVB (n=8) and by 146+/-56% in AF (n=8) goats (p<0.01). PKA-phosphorylated myosin-binding protein-C and troponin-I were reduced exclusively in AVB goat atria (by 75+/-10% and 55+/-15%, respectively, n=8, p<0.05). Atrial dilatation developing during slow ventricular rhythm after complete AV block as well as AF-induced remodeling are associated with atrial contractile dysfunction. Both AVB and AF goat atria show decreased SR Ca2+ load, likely caused by PLB dephosphorylation and RYR2 hyperphosphorylation. While shorter APs further compromise contractility in AF goat atria, reduced myofilament phosphorylation may impair contractility in AVB goat atria. Thus, atrial hypocontractility appears to have distinct molecular contributors in different types of atrial remodeling.

Genetics Home Reference: X-linked dilated cardiomyopathy

MedlinePlus

... Twitter Home Health Conditions X-linked dilated cardiomyopathy X-linked dilated cardiomyopathy Printable PDF Open All Close ... Javascript to view the expand/collapse boxes. Description X-linked dilated cardiomyopathy is a form of heart ...

Segmental dilatation of the ileum covered almost entirely by gastric mucosa: report of a case.

PubMed

Kobayashi, Tsutomu; Uchida, Nobuyuki; Shiojima, Masayuki; Sasamoto, Hajime; Shimura, Tatsuo; Takahasi, Atsusi; Kuwano, Hiroyuki

2007-01-01

A 13-year-old boy was referred to our hospital for investigation of intermittent abdominal colic pain and vomiting. He underwent an emergency laparotomy, which revealed a volvulus and segmental dilatation of the ileum. The dilated intestine was not associated with poor intestinal circulation. Because the dilated ileum did not seem to be the cause of the volvulus, we simply released the volvulus. However, after surgery, the patient still suffered from persistent abdominal pain, further episodes of volvulus, and invagination of the dilated ileum. Thus, we performed a second operation to resect the segmental dilatation of the ileum. Pathological examination revealed that most of the mucosa of the dilated ileum was composed of ectopic gastric mucosa. We postulate that the ectopic gastric mucosa led to the formation of segmental dilatation of the ileum.

The Effect of Commonly Performed Exercises on the Levator Hiatus Area and the Length and Strength of Pelvic Floor Muscles in Postpartum Women.

PubMed

Siff, Lauren N; Hill, Audra J; Walters, Samantha J; Walters, Ginny; Walters, Mark D

2018-05-02

The aim oft his study was to compare the effects of 10 common exercises to traditional pelvic floor muscle (PFM) contractions (Kegel) on levator hiatus (LH) area and PFM length and strength. This is a cross-sectional study of 15 healthy postpartum women. Ten exercises were studied. These were common variations of leg, core, and back exercises used in yoga, Pilates, strength training, and physical therapy. Each participant performed all 10 exercises at a single visit in 2 examination settings: transperineal ultrasound and perineometry. Ultrasound measured the LH area and PFM length, and perineometry measured the muscle strength (peak squeeze pressure). Kegel generates an increase in squeeze pressure (24.3 cm H2O), shortens the muscles (-0.46 cm) and narrows the LH (-0.13 cm). The bird-dog and plank exercises were not different from Kegel in any measurement. While the leg-lift ultrasound dimensions are similar to Kegel, leg lifts generated peak squeeze pressures stronger than any other exercise (including Kegel). Whereas ultrasound dimensions were similar to Kegel, tucked and untucked squats and thigh adductions generated weaker contractions than Kegel. While crunch generated a squeeze pressure similar to Kegel, the ultrasound dimensions showed a significantly wider LH and longer muscle than Kegel. Bridge, clam, and plié exercises affected the PFMs differently than Kegel in all measures. Bird-dog, plank, and leg-lift exercises should be evaluated as alternative exercises to Kegel as they affect PFM strength and length and LH area similarly to Kegel, and leg lifts generate a stronger contraction than Kegel.

Preliminary Design Guide for Arctic Equipment

DTIC Science & Technology

1989-05-01

areas that need to be addressed. The components of the various assemblies that Metals , plastics and elastomers make up the subject piece of equipment...polyester elastomer . Allow sufficient length for contraction (- 10- in./in, per IF). Do not allow long, unsup- ported lengths of hose . Lubricants Viscosity...this compressed air cools upon several manufacturers offer teflon hoses with expansion and contact with a cold surface, the braided stainless steel

Striation Patterns of Ox Muscle in Rigor Mortis

PubMed Central

Locker, Ronald H.

1959-01-01

Ox muscle in rigor mortis offers a selection of myofibrils fixed at varying degrees of contraction from sarcomere lengths of 3.7 to 0.7 µ. A study of this material by phase contrast and electron microscopy has revealed four distinct successive patterns of contraction, including besides the familiar relaxed and contracture patterns, two intermediate types (2.4 to 1.9 µ, 1.8 to 1.5 µ) not previously well described. PMID:14417790

The influence of confounding factors on the relationship between muscle contraction level and MF and MPF values of EMG signal: a review.

PubMed

Roman-Liu, Danuta

2016-01-01

The purpose of this article is to gather results of studies on the relationship between median frequency (MF) and mean power frequency (MPF) and the level of muscle contraction, and to use those results to discuss the differences in the trends according to factors related to measurement technique and subject. Twenty-one studies with 63 cases for upper limb muscles and nine studies with 31 cases for lower limb muscles were analysed. Most results showed an increase in parameters with an increased level of muscle contraction, only some studies showed a decrease. The influence on parameters of the level of muscle contraction and factors such as subjects, type of contraction, muscle length and electrodes was analysed for each muscle. It was concluded that when analysing the influence of different factors on MF and MPF, because those factors interact they should be considered together, not separately.

Contractility of glycerinated Amoeba proteus and Chaos-chaos.

PubMed

Rinaldi, R; Opas, M; Hrebenda, B

1975-05-01

Immediate contact with large volumes of cold 50% (v/v) buffered glycerol preserved typical ameboid shape of Chaos chaos and Amoeba proteus with no visible distortions. These technics allowed determination of the contraction sites in these glycerinated models upon applications of ATP-Ca-Mg-solutions. The ectoplasmic tube was the main site of contraction. Preliminary EM investigations revealed thick and thin filaments, associated with the ectoplasmic tube near the plasma-lemma, which appeared to be the basis for the contractility of the ectoplasmic tube. There was no predominant contraction of the pseudopodial tips or the endoplasm in these models. The changes of volume were as much as 50%, and in some cases were not accompanied by any change in the length of the ameba; however, lengthwise contractions of the ectoplasmic tube in some amebae occurred to as much as 25%. The data substantiate a basic requirement of the ectoplasmic tube contraction theory of ameboid locomotion.

Serum lactate dehydrogenase profile as a retrospective indicator of uterine preparedness for labor: a prospective, observational study

PubMed Central

2013-01-01

Background Lactate dehydrogenase (LDH) isoenzymes are required for adenosine triphosphate production, with each of five different isoenzymes having varying proficiencies in anaerobic versus aerobic environments. With advancing pregnancy, the isoenzyme profile in uterine muscle shifts toward a more anaerobic profile, speculatively to facilitate uterine efficiency during periods of low oxygen that accompany labor contractions. Profile shifting may even occur throughout labor. Maternal serum LDH levels between 24–48 hours following delivery predominantly originate from uterine muscle, reflecting the enzymatic state of the myometrium during labor. Our purpose was to describe serum LDH isoenzymes 24–30 hours post-delivery to determine if cervical dilation rates following labor admission were associated with a particular LDH profile. We also compared differences in post-delivery LDH isoenzyme profiles between women admitted in pre-active versus established active labor. Methods Low-risk, nulliparous women with spontaneous labor onset were sampled (n = 91). Maternal serum LDH was measured at labor admission and 24–30 hours post-vaginal delivery. Rates of cervical dilation during the first four hours after admission were also measured. Spearman’s rho coefficients were used for association testing and t tests evaluated for group and paired-sample differences. Results More efficient dilation following admission was associated with decreased LDH1 (p = 0.029) and increased LDH3 and LDH4 (p = 0.017 and p = 0.017, respectively) in the post-delivery period. Women admitted in established active labor had higher relative serum levels of LDH3 (t = 2.373; p = 0.023) and LDH4 (t = 2.268; p = 0.029) and lower levels of LDH1 (t = 2.073; p = 0.045) and LDH5 (t = 2.041; p = 0.048) when compared to women admitted in pre-active labor. Despite having similar dilatations at admission (3.4 ± 0.5 and 3.7 ± 0.6 cm, respectively), women admitted in pre-active labor had longer in-hospital labor durations (12.1 ± 4.3 vs. 5.3 ± 1.4 hours; p < 0.001) and were more likely to receive oxytocin augmentation (95.5% vs. 34.8%; p < 0.001). Conclusions More efficient cervical dilation following labor admission is associated with a more anaerobic maternal serum LDH profile in the post-delivery period. Since LDH profile shifting may occur throughout labor, watchful patience rather than intervention in earlier labor may allow LDH shifting within the uterus to more fully manifest. This may improve uterine efficiency during labor and decrease rates of oxytocin augmentation, thereby improving birth safety. PMID:23759027

Treatment for long bulbar urethral strictures with membranous involvement using urethroplasty with oral mucosa graft.

PubMed

Gimbernat, H; Arance, I; Redondo, C; Meilán, E; Andrés, G; Angulo, J C

2014-10-01

Urethroplasty with oral mucosa grafting is the most popular technique for treating nontraumatic bulbar urethral strictures; however, cases involving the membranous portion are usually treated using progressive perineal anastomotic urethroplasty. We assessed the feasibility of performing dorsal (or ventral) graft urethroplasty on bulbar urethral strictures with mainly membranous involvement using a modified Barbagli technique. This was a prospective study of 14 patients with bulbomembranous urethral strictures who underwent dilation urethroplasty with oral mucosa graft between 2005 and 2013, performed using a modified technique Barbagli, with proximal anchoring of the graft and securing of the graft to the tunica cavernosa in 12 cases (85.7%) and ventrally in 2 (14.3%). The minimum follow-up time was 1 year. We evaluated the subjective (patient satisfaction) and objective (maximum flow [Qmax] and postvoid residual volume [PVRV], preoperative and postoperative) results and complications. Failure was defined as the need for any postoperative instrumentation. A total of 14 patients (median age, 64+13 years) underwent surgery. The main antecedent of note was transurethral resection of the prostate in 9 cases (64.3%). The median length of the stenosis was 45+26.5mm. Prior to surgery, 50% of the patients had been subjected to dilatations and 4% to endoscopic urethrotomy. The mean surgical time and hospital stay were was 177+76min and 1.5+1 day, respectively. The preoperative Qmax and PVRV values were 4.5+4.45mL/sec and 212.5+130 cc, respectively. The postoperative values were 15.15+7.2mL/sec and 6+21.5cc, respectively (P<.01 for both comparisons). Surgery was successful in 13 cases (92.9%). None of the patients had major complications. There were minor complications in 1 (7.1%) patient, but reintervention was no required. The repair of long bulbar urethral strictures with membranous involvement using urethroplasty with free oral mucosa grafts represents a viable alternative for patients with nontraumatic etiology and little fibrosis. The dilation of the urethral lumen achieves good results with minimum failure rates and little probability of complications. For many of these patients, the length of the stricture is too long to perform the tension-free anastomosis technique. Copyright © 2014 AEU. Published by Elsevier Espana. All rights reserved.

Esophageal dilatation using the Eder Puestow dilators.

PubMed

Royston, C M; Dowling, B L; Gear, M W

1976-06-01

We have performed fifty-one dilatations in twenty-six patients using an end-viewing fiberoptic endoscope and Eder Puestow dilators. All (except two) were performed using intravenous diazepam, the majority on an outpatient basis. The only complication has been a single case of aspiration pneumonia. We have found this method of esophageal dilatation particularly useful in the preoperative dilatation of benign strictures, and in those elderly frail patients who are unsuitable for surgery. Transthoracic resection of the stricture is avoided and thus transabdominal repair of the hiatus hernia may be undertaken.

Comparative study of balloon and metal olive dilators for endoscopic management of benign anastomotic rectal strictures: clinical and cost-effectiveness outcomes.

PubMed

Xinopoulos, Dimitrios; Kypreos, Dimitrios; Bassioukas, Stefanos P; Korkolis, Dimitrios; Mavridis, Konstantinos; Scorilas, Andreas; Dimitroulopoulos, Dimitrios; Loukou, Argyro; Paraskevas, Emmanouel

2011-03-01

Postoperative anastomotic strictures frequently complicate colorectal resection. Currently, various endoscopic techniques are being employed in their management, but the establishment of an optimal therapeutic strategy is still pending. The purpose of our study is to compare through-the-scope (TTS) balloon dilators versus Eder-Puestow metal olive dilators in the treatment of postoperative benign rectal strictures, considering the clinical outcome and cost-effectiveness of each method. A total of 39 patients with benign anastomotic rectal stenosis were retrospectively studied. In group A, 15 patients underwent dilation with Eder-Puestow metal olives, while in group B 19 patients were treated by means of TTS balloon dilators. The technical and clinical success of dilation, complications, number of repeated sessions required, disease-free time intervals, and the overall cost of each procedure were evaluated. Dilations were technically successful in all patients. No major complications occurred in either group. The number of dilations needed, rate of stricture recurrence, and duration of stenosis-free time intervals were not statistically significantly different between the two groups. Both methods proved more effective in older patients, given the greater number of dilations required in younger patients of both groups and higher frequency of stricture relapse in younger balloon-dilated patients (median 64.00 years) compared with older ones (median 75.00 years) (p = 0.001). An indisputable advantage of the Eder-Puestow technique, compared with TTS balloon dilators, is the low cost of equipment (median 22.30 compared with 680 , respectively; p < 0.001). Endoscopic dilation of postoperative benign rectal strictures is equally effective and safe, especially in older patients, when performed by Eder-Puestow bougies or TTS balloon dilators. However, metal olivary tips seem to surpass balloon dilators when considering the obvious economical benefits of the first method.

Importance of anatomical dominance in the evaluation of coronary dilatation in Kawasaki disease.

PubMed

Dionne, Audrey; Hanna, Baher; Trinh Tan, Frédérick; Desjardins, Laurent; Lapierre, Chantale; Déry, Julie; Fournier, Anne; Dahdah, Nagib

2017-07-01

Introduction In Kawasaki disease, although coronary dilatation is attributed to vasculitis, the effect of myocardial inflammation is underestimated. Coronary dilatations are determined by Z-scores, which do not take into account dominance. The aim of the present study was to describe the impact of coronary dominance on dilatation in Kawasaki disease. We performed a retrospective analysis of coronary dilatations according to angiography categorisation of dominance. Of 28 patients (2.6 [0.2-10.1] years), right dominance was present in 15 patients and left in 13. Early dilatation was present in all patients, of whom 11 were ipsilateral to the dominant segment and 17 contralateral. Ipsilateral dilatations were present at diagnosis (9/11 versus 6/17, p=0.02) compared with contralateral dilatations, which developed 2 weeks after diagnosis (9/11 versus 16/17, p=0.29). Coronary artery Z-scores of patients with contralateral dilatation increased at 2 weeks, before returning to baseline values (2.0±2.2 at diagnosis, 4.1±1.8 at 2 weeks, 1.8±1.2 at 3-6 months, p=0.001), compared with patients with ipsilateral dilatation in whom Z-scores were maximal at diagnosis and remained stable (3.0±0.9, 2.7±1.1 and 2.6±1.5, respectively, p=0.13). Dominant coronary artery Z-scores were higher compared with non-dominant segments at diagnosis (3.0±0.9 versus 1.0±0.8, p<0.001) and at late follow-up (2.6±1.5 versus 0.4±1.4, p=0.002) in patients with ipsilateral dilatation. Progression of coronary dilatation after diagnosis may be a sign of dilatation secondary to vasculitis, as opposed to regression of Z-scores in ipsilateral dilatations, probably related to physiological vasodilatation in response to carditis. This needs to be validated in larger studies against vasculitic and myocardial inflammatory markers.

Modeling the pressure-dilatation correlation

NASA Technical Reports Server (NTRS)

Sarkar, S.

1991-01-01

It is generally accepted that pressure dilatation, which is an additional compressibility term in turbulence transport equations, may be important for high speed flows. Recent direct simulations of homogeneous shear turbulence have given concrete evidence that the pressure dilatation is important insofar that it contributes to the reduced growth of turbulent kinetic energy due to compressibility effects. The problem of modeling pressure dilatation is addressed. A component of the pressure dilatation is isolated which exhibits temporal oscillations and, using direct numerical simulations of homogeneous shear turbulence and isotropic turbulence, show that it has a negligible contribution to the evolution of turbulent kinetic energy. Then, an analysis for the case of homogeneous turbulence is performed to obtain a model for the nonoscillatory pressure dilatation. This model algebraically relates the pressure dilatation to quantities traditionally obtained in incompressible turbulence closures. The model is validated by direct comparison with the pressure dilatation data obtained from the simulations.

Histological Analysis of a New Route after Subintimal Crural Angioplasty.

PubMed

Akamatsu, Daijirou; Fujishima, Fumiyoshi; Goto, Hitoshi; Hashimoto, Munetaka; Tsuchida, Ken; Kawamura, Keiichirou; Tajima, Yuta; Umetsu, Michihisa; Suzuki, Syunya; Kamei, Takashi

2017-11-01

Subintimal angioplasty is an alternative approach in treating critical limb ischemia with crural artery disease. However, route or location of the newly created channel is not understood. A 68-year-old man was referred to our hospital with ischemic gangrene of the right big toe. We performed endovascular treatment because he was a poor candidate for bypass surgery. The posterior tibial artery was treated using subintimal angioplasty, although it resulted in early occlusion. We decided that he was not able to receive any further limb salvage treatment and performed amputation below the knee 7 days after treatment. The specimen from the origin of posterior tibial artery to plantar artery bifurcation was resected and the formalin-fixed vessel was cut into 39 segments. Histological analysis showed that the newly formed lumen was comparatively well dilated and created in the media by tearing internal elastic lamina in almost the whole of its length. The severely poor runoff vessels below the ankle were thought to be a main cause of early occlusion. The newly formed lumen by subintimal crural angioplasty could be well dilated and created in the media. Copyright © 2017 Elsevier Inc. All rights reserved.

Endoscopic management of Crohn’s strictures

PubMed Central

Bessissow, Talat; Reinglas, Jason; Aruljothy, Achuthan; Lakatos, Peter L; Van Assche, Gert

2018-01-01

Symptomatic intestinal strictures develop in more than one third of patients with Crohn’s disease (CD) within 10 years of disease onset. Strictures can be inflammatory, fibrotic or mixed and result in a significant decline in quality of life, frequently requiring surgery for palliation of symptoms. Patients under the age of 40 with perianal disease are more likely to suffer from disabling ileocolonic disease thus may have a greater risk for fibrostenotic strictures. Treatment options for fibrostenotic strictures are limited to endoscopic and surgical therapy. Endoscopic balloon dilatation (EBD) appears to be a safe, less invasive and effective alternative modality to replace or defer surgery. Serious complications are rare and occur in less than 3% of procedures. For non-complex strictures without adjacent fistulizaation or perforation that are less than 5 cm in length, EBD should be considered as first-line therapy. The aim of this review is to present the current literature on the endoscopic management of small bowel and colonic strictures in CD, which includes balloon dilatation, adjuvant techniques of intralesional injection of steroids and anti-tumor necrosis factor, and metal stent insertion. Short and long-term outcomes, complications and safety of EBD will be discussed. PMID:29740201

Minimally invasive myotomy for the treatment of esophageal achalasia: evolution of the surgical procedure and the therapeutic algorithm.

PubMed

Bresadola, Vittorio; Feo, Carlo V

2012-04-01

Achalasia is a rare disease of the esophagus, characterized by the absence of peristalsis in the esophageal body and incomplete relaxation of the lower esophageal sphincter, which may be hypertensive. The cause of this disease is unknown; therefore, the aim of the therapy is to improve esophageal emptying by eliminating the outflow resistance caused by the lower esophageal sphincter. This goal can be accomplished either by pneumatic dilatation or surgical myotomy, which are the only long-term effective therapies for achalasia. Historically, pneumatic dilatation was preferred over surgical myotomy because of the morbidity associated with a thoracotomy or a laparotomy. However, with the development of minimally invasive techniques, the surgical approach has gained widespread acceptance among patients and gastroenterologists and, consequently, the role of surgery has changed. The aim of this study was to review the changes occurred in the surgical treatment of achalasia over the last 2 decades; specifically, the development of minimally invasive techniques with the evolution from a thoracoscopic approach without an antireflux procedure to a laparoscopic myotomy with a partial fundoplication, the changes in the length of the myotomy, and the modification of the therapeutic algorithm.

Effects of overlapping electric double layer on mass transport of a macro-solute across porous wall of a micro/nanochannel for power law fluid.

PubMed

Bhattacharjee, Saikat; Mondal, Mrinmoy; De, Sirshendu

2017-05-01

Effects of overlapping electric double layer and high wall potential on transport of a macrosolute for flow of a power law fluid through a microchannel with porous walls are studied in this work. The electric potential distribution is obtained by coupling the Poisson's equation without considering the Debye-Huckel approximation. The numerical solution shows that the center line potential can be 16% of wall potential at pH 8.5, at wall potential -73 mV and scaled Debye length 0.5. Transport phenomena involving mass transport of a neutral macrosolute is formulated by species advective equation. An analytical solution of Sherwood number is obtained for power law fluid. Effects of fluid rheology are studied in detail. Average Sherwood number is more for a pseudoplastic fluid compared to dilatant upto the ratio of Poiseuille to electroosmotic velocity of 5. Beyond that, the Sherwood number is independent of fluid rheology. Effects of fluid rheology and solute size on permeation flux and concentration of neutral solute are also quantified. More solute permeation occurs as the fluid changes from pseudoplastic to dilatant. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mitral leaflet geometry perturbations with papillary muscle displacement and annular dilatation: an in-vitro study of ischemic mitral regurgitation.

PubMed

He, Shengqiu; Jimenez, Jorge; He, Zhaoming; Yoganathan, Ajit P

2003-05-01

Perturbations of leaflet geometry are the final end point through which left ventricular (LV) ischemia causes incomplete mitral leaflet closure and resultant mitral regurgitation (MR). Geometric inconsistencies observed with valvular or subvalvular structural alterations raise several questions. A new in-vitro LV flexible bag model was developed in order to visualize and analyze leaflet geometric changes under simulated pathological ischemic MR conditions. Papillary muscle (PM) displacement and annular dilatation decreased leaflet coaptation length, leading to significant MR. Symmetrical PM displacement shifted the coaptation line towards the leaflet edges and created central gaps along this line. Asymmetric PM displacement generated diametrically uneven coaptation with a tent-shaped leaflet at the tethered PM side, while the leaflet bulged at the opposite side towards the left atrium. Leaflet geometry during systole is affected by subvalvular structures. Asymmetric PM displacement, which may occur in regional or acute myocardial infarction, induces irregular deformation of the leaflet's coaptation line and, as a result, MR at the tethered side. Direct visualization of leaflet perturbation under these simulated pathological conditions may promote understanding of mechanisms present in ischemic MR.

In-vivo measurement of muscle tension: dynamic properties of the MC sensor during isometric muscle contraction.

PubMed

Đorđević, Srđan; Tomažič, Sašo; Narici, Marco; Pišot, Rado; Meglič, Andrej

2014-09-25

Skeletal muscle is the largest tissue structure in our body and plays an essential role for producing motion through integrated action with bones, tendons, ligaments and joints, for stabilizing body position, for generation of heat through cell respiration and for blood glucose disposal. A key function of skeletal muscle is force generation. Non-invasive and selective measurement of muscle contraction force in the field and in clinical settings has always been challenging. The aim of our work has been to develop a sensor that can overcome these difficulties and therefore enable measurement of muscle force during different contraction conditions. In this study, we tested the mechanical properties of a "Muscle Contraction" (MC) sensor during isometric muscle contraction in different length/tension conditions. The MC sensor is attached so that it indents the skin overlying a muscle group and detects varying degrees of tension during muscular contraction. We compared MC sensor readings over the biceps brachii (BB) muscle to dynamometric measurements of force of elbow flexion, together with recordings of surface EMG signal of BB during isometric contractions at 15° and 90° of elbow flexion. Statistical correlation between MC signal and force was very high at 15° (r = 0.976) and 90° (r = 0.966) across the complete time domain. Normalized SD or σN = σ/max(FMC) was used as a measure of linearity of MC signal and elbow flexion force in dynamic conditions. The average was 8.24% for an elbow angle of 90° and 10.01% for an elbow of angle 15°, which indicates high linearity and good dynamic properties of MC sensor signal when compared to elbow flexion force. The next step of testing MC sensor potential will be to measure tension of muscle-tendon complex in conditions when length and tension change simultaneously during human motion.

Etiology and Pathogenesis of Idiopathic Achalasia.

PubMed

Pressman, Amanda; Behar, Jose

2017-03-01

This review examines the etiology and pathogenesis of idiopathic achalasia. This disease is clinically characterized by dysphagia of solids and liquids due to the presence of simultaneous or absent esophageal contractions and impaired or absent relaxation of the lower esophageal sphincter. It includes a review of (a) etiology and pathogenesis of this inflammatory process that damage the ganglion cells of the Auerbach plexus that is limited to the esophagus; (b) genetic abnormalities and polymorphisms associated with this disease that may help explain its heterogeneity expressed by the different motility abnormalities of its phenotypes as well as differences in its clinical progression. These different genetic abnormalities may be responsible for the slow progression of types I or II phenotypes; (c) indirect evidence of viruses present in these patients that may initiate its development; (d) the abnormalities of the muscle layer that may be responsible for the dilation of the body of the esophagus that ultimately causes the sigmoid-like esophagus in the very last phase of this disease. This progression to the end-stage phase tends to occur in about 5% of patients. And, (e) the chronic inflammatory abnormalities in the squamous mucosa that may be the cause of the dysplastic and neoplastic changes that may lead to squamous cell carcinoma whose incidence in this disease is increased. These mucosal abnormalities are usually present in patients with markedly dilated body of the esophagus and severe food stasis.

Characterization of the mechanical behavior of sea ice as a frictional material

NASA Astrophysics Data System (ADS)

Lade, Poul V.

2002-12-01

The mechanical properties of sea ice are determined by the formation process, and the consequent material behavior at the element scale exhibits viscoelastic behavior at the early loading stages, followed by brittle fracture or ductile, irrecoverable deformation that may be captured by hardening/softening plasticity models with nonassociated flow. Failure of sea ice under different loading conditions follows a pattern that demonstrates its highly cross-anisotropic nature as well as its behavior as a frictional material. The interactions between the floes in the pack ice resemble those observed in granular materials. These materials are frictional in nature, they exhibit both contractive and dilative volume changes, the plastic flow is nonassociated, and their stiffnesses and strengths increase with confining pressure, but they do not have any strength when unconfined. The overall behavior of the pack ice may be close to isotropic. Constitutive modeling of this behavior may be achieved by models used in geotechnical engineering. Formation of leads and subsequent freezing of the water results in cementation between the ice floes, and the pack ice becomes stronger. The behavior of the pack ice may now be compared with that observed in cemented soils or concrete. For these materials, increasing amounts of cementation result in increasing rates of dilation when sheared, and this accounts for the largest contribution to the increase in shear strength.

Regulatory T cells are recruited in the infarcted mouse myocardium and may modulate fibroblast phenotype and function

PubMed Central

Saxena, Amit; Dobaczewski, Marcin; Rai, Vikrant; Haque, Zaffar; Chen, Wei; Li, Na

2014-01-01

Regulatory T cells (Tregs) play a pivotal role in suppressing immune responses regulating behavior and gene expression in effector T cells, macrophages, and dendritic cells. Tregs infiltrate the infarcted myocardium; however, their role the inflammatory and reparative response after myocardial infarction remains poorly understood. We used FoxP3EGFP reporter mice to study Treg trafficking in the infarcted heart and examined the effects of Treg depletion on postinfarction remodeling using an anti-CD25 antibody. Moreover, we investigated the in vitro effects of Tregs on cardiac fibroblast phenotype and function. Low numbers of Tregs infiltrated the infarcted myocardium after 24–72 h of reperfusion. Treg depletion had no significant effects on cardiac dysfunction and scar size after reperfused myocardial infarction but accelerated ventricular dilation and accentuated apical remodeling. Enhanced myocardial dilation in Treg-depleted animals was associated with increased expression of chemokine (C-C motif) ligand 2 and accentuated macrophage infiltration. In vitro, Tregs modulated the cardiac fibroblast phenotype, reducing expression of α-smooth muscle actin, decreasing expression of matrix metalloproteinase-3, and attenuating contraction of fibroblast-populated collagen pads. Our findings suggest that endogenous Tregs have modest effects on the inflammatory and reparative response after myocardial infarction. However, the anti-inflammatory and matrix-preserving properties of Tregs may suggest a role for Treg-based cell therapy in the attenuation of adverse postinfarction remodeling. PMID:25128167

Decreased Left Ventricular Torsion and Untwisting in Children with Dilated Cardiomyopathy

PubMed Central

Jin, Seon Mi; Bae, Eun Jung; Choi, Jung Yun; Yun, Yong Soo

2007-01-01

The purpose of this study was to analyze left ventricular (LV) torsion and untwisting, and to evaluate the correlation between torsion and other components of LV contraction in children with dilated cardiomyopathy (DCM). Segmental and global rotation, rotational rate (Vrot) were measured at three levels of LV using the two-dimensional (2D) speckle tracking imaging (STI) method in 10 DCM patients (range 0.6-15 yr, median 6.5 yr, 3 females) and 17 age- and sex-matched normal controls. Global torsion was decreased in DCM (peak global torsion; 10.9±4.6° vs. 0.3±2.1°, p<0.001). Loss of LV torsion occurred mainly by the diminution of counterclockwise apical rotation and was augmented by somewhat less reduction in clockwise basal rotation. In DCM, the normal counterclockwise apical rotation was not observed, and the apical rotation about the central axis was clockwise or slightly counterclockwise (peak apical rotation; 5.9±4.1° vs. -0.9±3.1°, p<0.001). Systolic counterclockwise Vrot and early diastolic clockwise Vrot at the apical level were decreased or abolished. In DCM, decreased systolic torsion and loss of early diastolic recoil contribute to LV systolic and diastolic dysfunction. The STI method may facilitate the serial evaluation of the LV torsional behavior in clinical settings and give new biomechanical concepts for better management of patients with DCM. PMID:17728501

Gα12 facilitates shortening in human airway smooth muscle by modulating phosphoinositide 3-kinase-mediated activation in a RhoA-dependent manner.

PubMed

Yoo, Edwin J; Cao, Gaoyuan; Koziol-White, Cynthia J; Ojiaku, Christie A; Sunder, Krishna; Jude, Joseph A; Michael, James V; Lam, Hong; Pushkarsky, Ivan; Damoiseaux, Robert; Di Carlo, Dino; Ahn, Kwangmi; An, Steven S; Penn, Raymond B; Panettieri, Reynold A

2017-12-01

PI3K-dependent activation of Rho kinase (ROCK) is necessary for agonist-induced human airway smooth muscle cell (HASMC) contraction, and inhibition of PI3K promotes bronchodilation of human small airways. The mechanisms driving agonist-mediated PI3K/ROCK axis activation, however, remain unclear. Given that G 12 family proteins activate ROCK pathways in other cell types, their role in M 3 muscarinic acetylcholine receptor-stimulated PI3K/ROCK activation and contraction was examined. Gα 12 coupling was evaluated using co-immunoprecipitation and serum response element (SRE)-luciferase reporter assays. siRNA and pharmacological approaches, as well as overexpression of a regulator of G-protein signaling (RGS) proteins were applied in HASMCs. Phosphorylation levels of Akt, myosin phosphatase targeting subunit-1 (MYPT1), and myosin light chain-20 (MLC) were measured. Contraction and shortening were evaluated using magnetic twisting cytometry (MTC) and micro-pattern deformation, respectively. Human precision-cut lung slices (hPCLS) were utilized to evaluate bronchoconstriction. Knockdown of M 3 receptors or Gα 12 attenuated activation of Akt, MYPT1, and MLC phosphorylation. Gα 12 coimmunoprecipitated with M 3 receptors, and p115RhoGEF-RGS overexpression inhibited carbachol-mediated induction of SRE-luciferase reporter. p115RhoGEF-RGS overexpression inhibited carbachol-induced activation of Akt, HASMC contraction, and shortening. Moreover, inhibition of RhoA blunted activation of PI3K. Lastly, RhoA inhibitors induced dilation of hPCLS. Gα 12 plays a crucial role in HASMC contraction via RhoA-dependent activation of the PI3K/ROCK axis. Inhibition of RhoA activation induces bronchodilation in hPCLS, and targeting Gα 12 signaling may elucidate novel therapeutic targets in asthma. These findings provide alternative approaches to the clinical management of airway obstruction in asthma. © 2017 The British Pharmacological Society.

Penile Inversion Vaginoplasty with or without Additional Full-Thickness Skin Graft: To Graft or Not to Graft?

PubMed

Buncamper, Marlon E; van der Sluis, Wouter B; de Vries, Max; Witte, Birgit I; Bouman, Mark-Bram; Mullender, Margriet G

2017-03-01

Penile inversion vaginoplasty is considered to be the gold standard for gender reassignment surgery in transgender women. The use of additional full-thickness skin graft as neovaginal lining is controversial. Some believe that having extra penile skin for the vulva gives better aesthetic results. Others believe that it gives inferior functional results because of insensitivity and skin graft contraction. Transgender women undergoing penile inversion vaginoplasty were studied prospectively. The option to add full-thickness skin graft is offered in patients where the penile skin length lies between 7 and 12 cm. Neovaginal depth was measured at surgery and during follow-up (3, 13, 26, and 52 weeks postoperatively). Satisfaction with the aesthetic result, neovaginal depth, and dilation regimen during follow-up were recorded. Satisfaction, sexual function, and genital self-image were assessed using questionnaires. A total of 100 patients were included (32 with and 68 without additional full-thickness skin graft). Patient-reported aesthetic outcome, overall satisfaction with the neovagina, sexual function, and genital self-image were not significantly associated with surgical technique. The mean intraoperative neovaginal depth was 13.8 ± 1.4 cm. After 1 year, this was 11.5 ± 2.5 cm. The largest decline (-15 percent) in depth is observed in the first 3 postoperative weeks (p < 0.01). The authors can confirm neither of the suggested arguments, for or against full-thickness skin graft use, in penile inversion vaginoplasty. The additional use of full-thickness skin graft does not influence neovaginal shrinkage, nor does it affect the patient- and physician-reported aesthetic or functional outcome. Therapeutic, IV.

Cardiomyopathy and Response to Enzyme Replacement Therapy in a Male Mouse Model for Fabry Disease

PubMed Central

Nguyen Dinh Cat, Aurelie; Escoubet, Brigitte; Agrapart, Vincent; Griol-Charhbili, Violaine; Schoeb, Trenton; Feng, Wenguang; Jaimes, Edgar; Warnock, David G.; Jaisser, Frederic

2012-01-01

Fabry disease is an X-linked disorder of glycosphingolipid metabolism that results in progressive accumulation of neutral glycosphingolipids, (predominately globotriaosylceramide; GL-3) in lysosomes, as well as other cellular compartments and the extracellular space. Our aim was to characterize the cardiac phenotype of male knock-out mice that are deficient in alpha-galactosidase A activity, as a model for Fabry disease and test the efficacy of Enzyme Replacement Therapy with agalsidase-beta. Male mice (3–4 months of age) were characterized with awake blood pressure and heart rate measurements, cardiac echocardiography and electrocardiography measurements under light anesthesia, histological studies and molecular studies with real-time polymerase chain reaction. The Fabry knock-out mouse has bradycardia and lower blood pressure than control wild type (CB7BL/6J) mice. In Fabry knock-out mice, the cardiomyopathy associated mild hypertrophy at echography with normal systolic LV function and mild diastolic dysfunction. Premature atrial contractions were more frequent in without conduction defect. Heart weight normalized to tibial length was increased in Fabry knock-out mice. Ascending aorta dilatation was observed. Molecular studies were consistent with early stages of cardiac remodeling. A single dose of agalsidase-beta (3 mg/kg) did not affect the LV hypertrophy, function or heart rate, but did improve the mRNA signals of early cardiac remodeling. In conclusion, the alpha-galactosidase A deficient mice at 3 to 4 months of age have cardiac and vascular alterations similar to that described in early clinical stage of Fabry disease in children and adolescents. Enzyme replacement therapy affects cardiac molecular remodeling after a single dose. PMID:22574107

Scaling and design of landslide and debris-flow experiments

USGS Publications Warehouse

Iverson, Richard M.

2015-01-01

Scaling plays a crucial role in designing experiments aimed at understanding the behavior of landslides, debris flows, and other geomorphic phenomena involving grain-fluid mixtures. Scaling can be addressed by using dimensional analysis or – more rigorously – by normalizing differential equations that describe the evolving dynamics of the system. Both of these approaches show that, relative to full-scale natural events, miniaturized landslides and debris flows exhibit disproportionately large effects of viscous shear resistance and cohesion as well as disproportionately small effects of excess pore-fluid pressure that is generated by debris dilation or contraction. This behavioral divergence grows in proportion to H3, where H is the thickness of a moving mass. Therefore, to maximize geomorphological relevance, experiments with wet landslides and debris flows must be conducted at the largest feasible scales. Another important consideration is that, unlike stream flows, landslides and debris flows accelerate from statically balanced initial states. Thus, no characteristic macroscopic velocity exists to guide experiment scaling and design. On the other hand, macroscopic gravity-driven motion of landslides and debris flows evolves over a characteristic time scale (L/g)1/2, where g is the magnitude of gravitational acceleration and L is the characteristic length of the moving mass. Grain-scale stress generation within the mass occurs on a shorter time scale, H/(gL)1/2, which is inversely proportional to the depth-averaged material shear rate. A separation of these two time scales exists if the criterion H/L < < 1 is satisfied, as is commonly the case. This time scale separation indicates that steady-state experiments can be used to study some details of landslide and debris-flow behavior but cannot be used to study macroscopic landslide or debris-flow dynamics.

Resveratrol and polydatin as modulators of Ca2+ mobilization in the cardiovascular system.

PubMed

Liu, Wenjuan; Chen, Peiya; Deng, Jianxin; Lv, Jingzhang; Liu, Jie

2017-09-01

In the cardiovascular system, Ca 2+ controls cardiac excitation-contraction coupling and vascular contraction and dilation. Disturbances in intracellular Ca 2+ homeostasis induce malfunctions of the cardiovascular system, including cardiac pump dysfunction, arrhythmia, remodeling, and apoptosis, as well as hypertension and impairment of vascular reactivity. Therefore, developing drugs and strategies manipulating Ca 2+ handling are highly valued in the treatment of cardiovascular disease. Resveratrol (Res) and polydatin (PD), a Res glucoside, have been well established to have beneficial effects on improving cardiovascular function. Studies from our laboratory and others have demonstrated that they exhibit inotropic effects on normal heart and therapeutic effects on hypertension, cardiac ischemia/reperfusion injury, hypertrophy, and heart failure by manipulating Ca 2+ mobilization. The actions of Res and PD on Ca 2+ signals delicately manipulated by multiple Ca 2+ -handling proteins are pleiotropic and somewhat controversial, depending on cellular species and intracellular oxidative status. Here, we focus on the effects of Res and PD on controlling Ca 2+ homeostasis in the heart and vasculature under normal and diseased conditions and highlight the key direct and indirect molecules mediating these effects. © 2017 New York Academy of Sciences.

Bitter taste receptors on airway smooth muscle bronchodilate by localized calcium signaling and reverse obstruction.

PubMed

Deshpande, Deepak A; Wang, Wayne C H; McIlmoyle, Elizabeth L; Robinett, Kathryn S; Schillinger, Rachel M; An, Steven S; Sham, James S K; Liggett, Stephen B

2010-11-01

Bitter taste receptors (TAS2Rs) on the tongue probably evolved to evoke signals for avoiding ingestion of plant toxins. We found expression of TAS2Rs on human airway smooth muscle (ASM) and considered these to be avoidance receptors for inhalants that, when activated, lead to ASM contraction and bronchospasm. TAS2R agonists such as saccharin, chloroquine and denatonium evoked increased intracellular calcium ([Ca²(+)](i)) in ASM in a Gβγ-, phospholipase Cβ (PLCβ)- and inositol trisphosphate (IP₃) receptor-dependent manner, which would be expected to evoke contraction. Paradoxically, bitter tastants caused relaxation of isolated ASM and dilation of airways that was threefold greater than that elicited by β-adrenergic receptor agonists. The relaxation induced by TAS2Rs is associated with a localized [Ca²(+)](i) response at the cell membrane, which opens large-conductance Ca²(+)-activated K(+) (BK(Ca)) channels, leading to ASM membrane hyperpolarization. Inhaled bitter tastants decreased airway obstruction in a mouse model of asthma. Given the need for efficacious bronchodilators for treating obstructive lung diseases, this pathway can be exploited for therapy with the thousands of known synthetic and naturally occurring bitter tastants.

Treatment of oropharyngeal dysphagia secondary to idiopathic cricopharyngeal bar: Surgical cricopharyngeal muscle myotomy versus dilation.

PubMed

Marston, Alexander P; Maldonado, Francisco J; Ravi, Karthik; Kasperbauer, Jan L; Ekbom, Dale C

To compare swallowing outcomes following cricopharyngeal (CP) dilation versus surgical myotomy in patients with dysphagia secondary to idiopathic CP bar. All patients had an idiopathic CP bar without a history of Zenker's diverticulum, head and neck cancer, or systemic neurologic disease treated between 2000 and 2013. The Functional Outcome Swallowing Scale (FOSS) was utilized to assess dysphagia symptoms. Twenty-three patients underwent 46 dilations and 20 patients had a myotomy. Nineteen of 23 (83%) patients in the dilation group and all patients in the myotomy group reported improved swallow function. The median difference in pre- versus post-intervention FOSS scores was not statistically significant (p=0.07) between the dilation and myotomy groups with mean reductions of 1.3 and 1.8, respectively. Seventeen of 23 (74%) dilation patients had persistent or recurrent dysphagia with 13 (57%) requiring repeat dilation and 4 (17%) undergoing CP myotomy. The median time to first reintervention in the dilation group was 13.6months. Nineteen of 20 (95%) surgical myotomy patients did not experience recurrent dysphagia. Both endoscopic CP dilation and myotomy led to similar initial improvement in swallow function for patients with primary idiopathic CP bar; however, dilation is more likely to provide temporary benefit. Copyright © 2016 Elsevier Inc. All rights reserved.

Use of a lumen-apposing metal stent to treat GI strictures (with videos).

PubMed

Irani, Shayan; Jalaj, Sujai; Ross, Andrew; Larsen, Michael; Grimm, Ian S; Baron, Todd H

2017-06-01

Benign GI strictures occur typically in the esophagus and pyloric channel but can occur anywhere in the GI tract and at anastomotic sites. Such strictures can be treated with dilation, incisional therapy, steroid injection, and stents. Our aim was to describe the use of a lumen-apposing metal stent (LAMS) to treat short, benign GI strictures. Consecutive patients who underwent LAMS placement for various benign strictures at 2 tertiary care centers from August 2014 to November 2015 were reviewed retrospectively. The main outcome measures were technical success, clinical success, stent migration, and adverse events. Twenty-five patients (7 males, 18 females) with a median age of 54 years (33-85 years) underwent 28 LAMS placements to treat various benign strictures. The location of the strictures included esophagogastric anastomoses (n=4), gastrojejunal anastomoses (n=13), pylorus (n=6), vertical banded gastroplasty (n=1), and ileocolonic anastomosis (n=1). Twenty patients had been previously treated with dilation alone (9 patients with ≥3 dilations), 11 patients with dilation and steroid injection, 2 patients with additional needle-knife therapy, and 1 patient with placement of a traditional fully covered self-expandable metal stent. A 15-mm internal diameter LAMS was placed in all patients; 3 patients had been treated previously with a 10-mm LAMS. Technical success was achieved in all patients, whereas clinical success was achieved in 15 of 25 patients (60%) who completed a minimum of 6 months of follow-up after placement. Median stent dwell time was 92 days (range, 3-273 days). Stent migration was seen in 2 of 28 stent placements (7%). Four of 25 patients (16%) developed 5 moderate adverse events (pain requiring removal, 2; new stricture formation, 2; bleeding, 1). Median follow-up was 301 days after stent placement. Study limitations include the small, select group of patients, the retrospective study design, and short follow-up. LAMS placement for benign GI strictures is technically easy and safe with low migration rates and may be an option to treat selected patients with short-length strictures. Copyright © 2017 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.

Triceps surae muscle-tendon unit length changes as a function of ankle joint angles and contraction levels: the effect of foot arch deformation.

PubMed

Iwanuma, Soichiro; Akagi, Ryota; Hashizume, Satoru; Kanehisa, Hiroaki; Yanai, Toshimasa; Kawakami, Yasuo

2011-09-23

The purpose of this study was to clarify how foot deformation affects the relationship between triceps surae muscle-tendon unit (MTU) length and ankle joint angle. For six women and six men a series of sagittal magnetic resonance (MR) images of the right foot were taken, and changes in MTU length (the displacement of the calcaneal tuberosity), foot arch angle, and ankle joint angle were measured. In the passive session, each subject's ankle joint was secured at 10° dorsiflexed position, neutral position (NP), and 10° and 20° plantar flexed positions while MR images were acquired. In the active session, each subject was requested to perform submaximal isometric plantar flexions (30%, 60%, and 80% of voluntary maximum) at NP. The changes in MTU length in each trial were estimated by two different formulae reported previously. The changes of the measured MTU length as a function of ankle joint angles observed in all trials of the active session were significantly (p<0.05) larger than corresponding values in the passive session and by the estimation formulae. In the passive session, MTU length changes were significantly smaller than the estimated values when the ankle was plantar flexed. The foot arch angle increased as the contraction level increased from rest (117 ± 4°) to 80% (125 ± 3°), and decreased as the ankle was positioned further into plantar flexion in the passive session (115 ± 3°). These results indicate that foot deformation profoundly affects the triceps surae MTU length-ankle joint angle relationship during plantar flexion. Copyright © 2011 Elsevier Ltd. All rights reserved.

On Optimum Power Allocation for Multi-Antenna Wideband Helicopter-to-Ground Communications

DTIC Science & Technology

2014-03-01

optimum [1]. In frequency selective fading, the general approach is to use OFDM and apply these techniques on a per subcarrier basis. This work was...Contracting Office under contract W900KK-09-C-0016. Given the constraints described above, OFDM is often of limited interest in helicopter-to-ground...Naguib, and R. Calderbank, “Finite-length MIMO decision feedback equalization for space-time block-coded signals over multipath-fading channels,” IEEE

Defense AT and L Magazine. Volume 45, Number 2, March-April 2016

DTIC Science & Technology

2016-03-01

preferred contract type (Fixed Price Incentive Firm and Cost Plus Incentive Fee may be effective) 5. Provide sufficient contract length for the...example would be an incentive on pay- load margin for our medium launch vehicle, where the mini - mum requirement is 100 pounds of margin and the...involving a mini -UAV initiative with Indian industry partners. In discussing the Make in India initiative, U.S. officials note that it requires time

Role of rho-kinase (ROCK) in tonic but not phasic contraction in the frog stomach smooth muscle.

PubMed

Sahin, Leyla; Cevik, Ozge Selin; Koyuncu, Dilan Deniz; Buyukafsar, Kansu

2018-04-01

Rho/Rho-kinase (ROCK) signaling has extensively been shown to take part in mammalian smooth muscle contractions in response to diverse agents yet its role in the contraction of amphibian smooth muscle has not been investigated. Therefore, we aimed to explore any role of this pathway in the contractions of frog stomach smooth. The strips were prepared and suspended in organ baths filled with Ringer solution. Changes in the circular strips of the frog stomach muscle length were recorded isotonically with a force transducer in organ baths. Carbachol (CCh) exerted both phasic and tonic contractions. In contrast, atropin abolished all types of contractions by CCh. The phasic contractions were suppressed by a Ca 2+ channel blocker, nifedipine but not by the ROCK inhibitor, Y-27632. However, the tonic contractions were markedly attenuated by Y-27632. Selective M 1 receptor blocker, pirenzepin, selective M 3 receptor blocker and DAMP had no effects on CCh-elicited contractions. On the other hand, selective M 2 receptor blocker, AF-DX suppressed all types of contractile activity by CCh. These data suggest that M 2 receptor activation could mainly mediate CCh-induced phasic and tonic contractions, and ROCK seems to be involved in the CCh-induced tonic but not phasic contractions of the frog stomach smooth muscle. Copyright © 2018 Elsevier Inc. All rights reserved.

MSH3 Promotes Dynamic Behavior of Trinucleotide Repeat Tracts In Vivo

PubMed Central

Williams, Gregory M.; Surtees, Jennifer A.

2015-01-01

Trinucleotide repeat (TNR) expansions are the underlying cause of more than 40 neurodegenerative and neuromuscular diseases, including myotonic dystrophy and Huntington’s disease, yet the pathway to expansion remains poorly understood. An important step in expansion is the shift from a stable TNR sequence to an unstable, expanding tract, which is thought to occur once a TNR attains a threshold length. Modeling of human data has indicated that TNR tracts are increasingly likely to expand as they increase in size and to do so in increments that are smaller than the repeat itself, but this has not been tested experimentally. Genetic work has implicated the mismatch repair factor MSH3 in promoting expansions. Using Saccharomyces cerevisiae as a model for CAG and CTG tract dynamics, we examined individual threshold-length TNR tracts in vivo over time in MSH3 and msh3Δ backgrounds. We demonstrate, for the first time, that these TNR tracts are highly dynamic. Furthermore, we establish that once such a tract has expanded by even a few repeat units, it is significantly more likely to expand again. Finally, we show that threshold- length TNR sequences readily accumulate net incremental expansions over time through a series of small expansion and contraction events. Importantly, the tracts were substantially stabilized in the msh3Δ background, with a bias toward contractions, indicating that Msh2-Msh3 plays an important role in shifting the expansion-contraction equilibrium toward expansion in the early stages of TNR tract expansion. PMID:25969461

Temporal evolution of intraocular pressure elevation after pupillary dilation in pigment dispersion syndrome.

PubMed

Jewelewicz, Daniel A; Radcliffe, Nathan M; Liebmann, Jeffrey; Ritch, Robert

2009-03-01

To report 4 patients with pigment dispersion syndrome (PDS) who had delayed intraocular pressure (IOP) spikes after pharmacologic pupillary dilation. Four patients with a diagnosis of PDS with documented IOP spike after pharmacologic pupillary dilation were included. Study patients were examined before and after pupillary dilation. The amount of pigment present in the anterior chamber and the IOP were measured at hourly intervals. Although maximal pigment liberation occurred immediately after maximal dilation, the IOP continued to elevate for at least 1.5 hours. The increase in IOP after pupillary dilation may not occur simultaneously with maximal pigment liberation but may follow it after the pigment has settled out of the anterior chamber. This has implications for monitoring patients with PDS after dilation to detect and treat rises in IOP.

The Arithmetic of events and a new theory of Gravitation

NASA Astrophysics Data System (ADS)

Abbasi, Malek

2012-04-01

Of fundamental importance in physics is the concept of event. This study tries; first, to provide a mathematical background showing how must deal with these events and based on what laws the watches, another important concept used frequently in this research, record them. Armed, then, with this mathematical background, the Gravitational Clouds Theory, a novel theory of gravitation concerning the role of the matter and energy in the universe, is proposed. This completely new theory leads to miscellanies results some of which are: the second Einstein's postulate; the well known identity E = mc2; the time-dilation phenomenon and Fitzgerald-Lorentz contraction. This theory will also explain why indeed we never feel the speed of the Earth, what is the origin of Dark matter-energy and many other extraordinary results associated with cosmology.

The Arithmetic of Events and a New Theory of Gravitation

NASA Astrophysics Data System (ADS)

Abbasi, Malek

2012-10-01

Of fundamental importance in physics is the concept of event. This study tries, first, to provide a mathematical background showing how must deal with these events and based on what laws the watches, another important concept used frequently in this research, record them. Armed, then, with this mathematical background, the Gravitational Clouds Theory, a novel theory of gravitation concerning the role of the matter and energy in the universe, is proposed. This completely new theory leads to miscellanies results some of which are: the second Einstein's postulate; the well known identity E = mc2; the time-dilation phenomenon and Fitzgerald-Lorentz contraction. This theory will also explain why indeed we never feel the speed of the Earth, what is the origin of Dark matter-energy and many other extraordinary results associated with cosmology.

Treatment of benign esophageal stricture by Eder-Puestow or balloon dilators: a comparison between randomized and prospective nonrandomized trials.

PubMed

Yamamoto, H; Hughes, R W; Schroeder, K W; Viggiano, T R; DiMagno, E P

1992-03-01

To determine whether the natural history of strictures is affected by the type of dilator used to treat newly diagnosed peptic strictures, we designed a prospective randomized trial to compare the results after Eder-Puestow or Medi-Tech balloon dilation. We entered 31 patients into the trial. We also prospectively followed up all 92 nonrandomized patients who underwent their first dilation for a benign stricture during the same period as the prospective randomized trial. The nonrandomized patients also underwent dilation with either the Eder-Puestow or the balloon technique at the discretion of the gastroenterologist performing the endoscopy. We found no statistically significant differences in the immediate or long-term results of the two methods among the randomized, nonrandomized, and overall combined groups. All but 1 of the 123 patients had immediate relief of dysphagia. Within each group of patients, the probability of remaining free of dysphagia 1 year after the initial dilation was approximately 20%, and the probability of not requiring a second dilation was approximately 65% with either technique. Major (esophageal rupture) and minor (bleeding or chest pain) complications occurred in 1% and 5% of the patients and 0.4% and 3% of the total dilation procedures, respectively. The esophageal rupture and four of six minor complications occurred after repeated dilations. Five of the six minor complications occurred with use of the Eder-Puestow dilators. We conclude that Eder-Puestow and balloon dilations of benign esophageal strictures are associated with similar outcomes, but repeated dilations and the Eder-Puestow technique may be associated with an increased risk of complications.

Cervical Dilatation Curves of Spontaneous Deliveries in Pregnant Japanese Females

PubMed Central

Inde, Yusuke; Nakai, Akihito; Sekiguchi, Atsuko; Hayashi, Masako; Takeshita, Toshiyuki

2018-01-01

Background: Although cervical dilatation curves are crucial for appropriate management of labor progression, abnormal labor progression and obstetric interventions were included in previous and widely-used cervical dilatation curves. We aimed to describe the cervical dilatation curves of normal labor progression in pregnant Japanese females without abnormal labor progression and obstetric interventions. Methods: We completed retrospective obstetric record reviews on 3172 pregnant Japanese females (parity = 0, n = 1047; parity = 1, n = 1083; parity ≥ 2, n = 1042), aged 20 to 39 years old at delivery, with pregravid body mass indices of less than 30. All patients underwent spontaneous deliveries with term, singleton, cephalic and live newborns of appropriate-for-gestational age birthweight, without adverse neonatal outcomes. We characterized labor progression patterns by examining the relationship between elapsed times from the full dilatation and cervical dilatation stages, and labor durations by examining the distribution of time intervals from one cervical dilatation stage, to the next, and ultimately to the full dilatation. Results: Fastest cervical changes occurred at 6 cm (primiparas) and 5 cm (multiparas) of dilatation. The 95%tile of labor progression took over 3 hours to progress from 6 cm to 7 cm (primiparas), and over 2 hours to progress from 5 cm to 6 cm (multiparas). The 5%tile of traverse time to the full dilatation, during the active phase, was less than 1 hour (primiparas) and 0.5 hours (multiparas). At the end of the active phase, no deceleration phase was observed. Conclusions: Active labor may not start until 5 cm of dilatation. At the beginning of the active phase, cervical dilatation was slower than previously described. These results may reduce opportunities for obstetric interventions during labor progression. PMID:29725244

Dilation or biodegradable stent placement for recurrent benign esophageal strictures: a randomized controlled trial.

PubMed

Walter, Daisy; van den Berg, Maarten W; Hirdes, Meike M; Vleggaar, Frank P; Repici, Alessandro; Deprez, Pierre H; Viedma, Bartolomé L; Lovat, Laurence B; Weusten, Bas L; Bisschops, Raf; Haidry, Rehan; Ferrara, Elisa; Sanborn, Keith J; O'Leary, Erin E; van Hooft, Jeanin E; Siersema, Peter D

2018-06-08

 Dilation is the standard of care for recurrent benign esophageal strictures (BES). Biodegradable stents may prolong the effect of dilation and reduce recurrences. Efficacy and safety of dilation and biodegradable stent placement early in the treatment algorithm of recurrent BES were compared.  This multicenter, randomized study enrolled patients with BES treated with previous dilations to ≥ 16 mm. The primary end point was number of repeat endoscopic dilations for recurrent stricture within 3 and 6 months. Secondary outcomes through 12 months included safety, time to first dilation for recurrent stricture, dysphagia, and level of activity.  At 3 months, the biodegradable stent group (n = 32) underwent significantly fewer endoscopic dilations for recurrent stricture compared with the dilation group (n = 34; P  < 0.001). By 6 months, the groups were similar. The number of patients experiencing adverse events was similar between the groups. Two patients in the biodegradable stent group died after developing tracheoesophageal fistulas at 95 and 96 days post-placement; no deaths were attributed to the stent. Median time to first dilation of recurrent stricture for the biodegradable stent group was significantly longer (106 vs. 41.5 days; P  = 0.003). Dysphagia scores improved for both groups. Patients in the biodegradable stent group had a significantly higher level of activity through 12 months ( P  < 0.001).  Biodegradable stent placement is associated with temporary reduction in number of repeat dilations and prolonged time to recurrent dysphagia compared with dilation. Additional studies are needed to better define the exact role of biodegradable stent placement to treat recurrent BES. © Georg Thieme Verlag KG Stuttgart · New York.

Effect of pupillary dilatation on glaucoma assessments using optical coherence tomography

PubMed Central

Smith, Michael; Frost, Andrew; Graham, Christopher Mark; Shaw, Steven

2007-01-01

Aims To examine the effect of pupillary dilatation on the reliability of retinal nerve fibre layer (RNFL) and optic nerve head (ONH) assessments using Stratus OCT in a glaucoma clinic. Methods Observational study of 38 patients attending a glaucoma clinic. The “fast optic disc” and “fast RNFL thickness” programs on Stratus OCT were used to measure the RNFL thickness and ONH cup to disc ratio (CDR). Two scans were done before dilatation and two after dilatation with tropicamide 1% drops. The mean values and reproducibility before and after dilatation were compared, along with the quality of scans as indicated by the “signal strength” score. Results In nine patients (23.7%) no images were obtained undilated but after dilatation examination was possible in all patients. Inability to obtain an undilated scan was associated with smaller pupil size and increasing cataract. The scan quality, as judged by the signal strength score, was higher dilated than undilated for both RNFL thickness (p = 0.011) and ONH CDR (p = 0.007). Reproducibility was higher with dilated scans for RNFL thickness but not for ONH CDR. There were significant differences between the dilated and undilated examinations for three of the five RNFL thickness variables and two of the three ONH CDR categories. Conclusions Acquisition of high quality OCT images was not possible without pupillary dilatation in about 25% of the patients. The dilated scans were more reproducible and of higher quality than the undilated scans. The two methods of examination do not appear to be interchangeable, suggesting that in follow up examinations the pupil should be in the same condition as at baseline. Pupillary dilatation is recommended before glaucoma assessments using Stratus OCT. PMID:17556429

Application of Electrocautery Needle Knife Combined with Balloon Dilatation versus Balloon Dilatation in the Treatment of Tracheal Fibrotic Scar Stenosis.

PubMed

Bo, Liyan; Li, Congcong; Chen, Min; Mu, Deguang; Jin, Faguang

Electrocautery needle knives can largely reduce scar and granulation tissue hyperplasia and play an important role in treating patients with benign stricture. The aim of this retrospective study was to evaluate the efficacy and safety of electrocautery needle knife combined with balloon dilatation versus balloon dilatation alone in the treatment of tracheal stenosis caused by tracheal intubation or tracheotomy. We retrospectively analysed the clinical data of 43 patients with tracheal stenosis caused by tracheotomy or tracheal intubation in our department from January 2013 to January 2016. Among these 43 patients, 23 had simple web-like stenosis and 20 had complex steno sis. All patients were treated under general anaesthesia, and the treatment methods were (1) balloon dilatation alone, (2) needle knife excision of fibrotic tissue combined with balloon dilatation, and (3) needle knife radial incision of fibrotic tissue combined with balloon dilatation. After treatment the symptoms, such as shortness of breath, were markedly improved immediately in all cases. The stenosis degree of patients who were treated with the elec-trocautery needle knife combined with balloon dilatation had better improvement compared with that of those treated with balloon dilatation treatment alone after 3 months (0.45 ± 0.04 vs. 0.67 ± 0.05, p < 0.01), and the proportion of restenosis occurrence that required further treatment was decreased at 6 months (46.9 vs. 81.8%), especially for the web-like stenosis patients, as most of their stenoses dilated with no obvious restenosis and achieved clinical cure. Electrocautery needle knife combined with balloon dilatation is an effective and safe treatment for tracheal fibrotic stenosis compared with balloon dilatation alone. © 2017 S. Karger AG, Basel.

Office-based esophageal dilation in head and neck cancer: Safety, feasibility, and cost analysis.

PubMed

Howell, Rebecca J; Schopper, Melissa A; Giliberto, John Paul; Collar, Ryan M; Khosla, Sid M

2018-02-08

To review experience, safety, and cost of office-based esophageal dilation in patients with history of head and neck cancer (HNCA). The medical records of patients undergoing esophageal dilation in the office were retrospectively reviewed between August 2015 and May 2017. Patients were given nasal topical anesthesia. Next, a transnasal esophagoscopy (TNE) was performed. If the patient tolerated TNE, we proceeded with esophageal dilation using Seldinger technique with the CRE™ Boston Scientific (Boston Scientific Corp., Marlborough, MA) balloon system. Patients were discharged directly from the outpatient clinic. Forty-seven dilations were performed in 22 patients with an average of 2.1 dilations/patient (range 1-10, standard deviation [SD] ± 2.2). Seventeen patients (77%) were male. The average age was 67 years (range 35-78 years, SD ± 8.5). The most common primary site of cancer was oral cavity/oropharynx (n = 10), followed by larynx (n = 6). All patients (100%) had history of radiation treatment. Four patients were postlaryngectomy. The indication for esophageal dilation was esophageal stricture and progressive dysphagia. All dilations occurred in the proximal esophagus. There were no major complications. Three focal, superficial lacerations occurred. Two patients experienced mild, self-limited epistaxis. One dilation was poorly tolerated due to discomfort. One patient required pain medication postprocedure. Office-based esophageal dilation generated $15,000 less in health system charges compared to traditional operating room dilation on average per episode of care. In patients with history of HNCA and radiation, office-based TNE with esophageal dilation appears safe, well-tolerated, and cost-effective. In a small cohort, the technique has low complication rate and is feasible in an otolaryngology outpatient office setting. 4. Laryngoscope, 2018. © 2018 The American Laryngological, Rhinological and Otological Society, Inc.

Pneumomediastinum after self-dilation of the esophagus.

PubMed

Noppen, M M; Corne, L; Peters, O; Smekens, L; Musch, W; Vincken, W

1987-10-01

Pneumomediastinum following esophageal perforation is a known complication of Eder Puestow dilation for esophageal stenosis. This is the first reported case of esophageal perforation and pneumomediastinum occurring after instrumental self-dilation of a stenotic esophageal lesion. The observed 0.02 percent perforation rate in this patient (compared to the reported 0.3 percent in Eder Puestow "hetero"-dilation) makes the Eder Puestow auto-dilation procedure seem justifiable in a well-trained and well-informed patient.

Genetic deletion of muscle RANK or selective inhibition of RANKL is not as effective as full-length OPG-fc in mitigating muscular dystrophy.

PubMed

Dufresne, Sébastien S; Boulanger-Piette, Antoine; Bossé, Sabrina; Argaw, Anteneh; Hamoudi, Dounia; Marcadet, Laetitia; Gamu, Daniel; Fajardo, Val A; Yagita, Hideo; Penninger, Josef M; Russell Tupling, A; Frenette, Jérôme

2018-04-24

Although there is a strong association between osteoporosis and skeletal muscle atrophy/dysfunction, the functional relevance of a particular biological pathway that regulates synchronously bone and skeletal muscle physiopathology is still elusive. Receptor-activator of nuclear factor κB (RANK), its ligand RANKL and the soluble decoy receptor osteoprotegerin (OPG) are the key regulators of osteoclast differentiation and bone remodelling. We thus hypothesized that RANK/RANKL/OPG, which is a key pathway for bone regulation, is involved in Duchenne muscular dystrophy (DMD) physiopathology. Our results show that muscle-specific RANK deletion (mdx-RANK mko ) in dystrophin deficient mdx mice improves significantly specific force [54% gain in force] of EDL muscles with no protective effect against eccentric contraction-induced muscle dysfunction. In contrast, full-length OPG-Fc injections restore the force of dystrophic EDL muscles [162% gain in force], protect against eccentric contraction-induced muscle dysfunction ex vivo and significantly improve functional performance on downhill treadmill and post-exercise physical activity. Since OPG serves a soluble receptor for RANKL and as a decoy receptor for TRAIL, mdx mice were injected with anti-RANKL and anti-TRAIL antibodies to decipher the dual function of OPG. Injections of anti-RANKL and/or anti-TRAIL increase significantly the force of dystrophic EDL muscle [45% and 17% gains in force, respectively]. In agreement, truncated OPG-Fc that contains only RANKL domains produces similar gains, in terms of force production, than anti-RANKL treatments. To corroborate that full-length OPG-Fc also acts independently of RANK/RANKL pathway, dystrophin/RANK double-deficient mice were treated with full-length OPG-Fc for 10 days. Dystrophic EDL muscles exhibited a significant gain in force relative to untreated dystrophin/RANK double-deficient mice, indicating that the effect of full-length OPG-Fc is in part independent of the RANKL/RANK interaction. The sarco/endoplasmic reticulum Ca 2+ ATPase (SERCA) activity is significantly depressed in dysfunctional and dystrophic muscles and full-length OPG-Fc treatment increased SERCA activity and SERCA-2a expression. These findings demonstrate the superiority of full-length OPG-Fc treatment relative to truncated OPG-Fc, anti-RANKL, anti-TRAIL or muscle RANK deletion in improving dystrophic muscle function, integrity and protection against eccentric contractions. In conclusion, full-length OPG-Fc represents an efficient alternative in the development of new treatments for muscular dystrophy in which a single therapeutic approach may be foreseeable to maintain both bone and skeletal muscle functions.

Characterization of muscle contraction with second harmonic generation microscopy

NASA Astrophysics Data System (ADS)

Prent, Nicole

Muscle cells have the ability to change length and generate force due to orchestrated action of myosin nanomotors that cause sliding of actin filaments along myosin filaments in the sarcomeres, the fundamental contractile units, of myocytes. The correlated action of hundreds of sarcomeres is needed to produce the myocyte contractions. This study probes the molecular structure of the myofilaments and investigates the movement correlations between sarcomeres during contraction. In this study, second harmonic generation (SHG) microscopy is employed for imaging striated myocytes. Myosin filaments in striated myocytes inherently have a nonzero second-order susceptibility, [special characters omitted] and therefore generate efficient SHG. Employing polarization-in polarization-out (PIPO) SHG microscopy allows for the accurate determination of the characteristic ratio, [special characters omitted] in birefringent myocytes, which describes the structure of the myosin filament. Analysis shows that the b value at the centre of the myosin filament, where the nonlinear dipoles are better aligned, is slightly lower than the value at the edges of the filament, where there is more disorder in orientation of the nonlinear dipoles from the myosin heads. Forced stretching of myocytes resulted in an SHG intensity increase with the elongation of the sarcomere. SHG microscopy captured individual sarcomeres during contraction, allowing for the measurement of sarcomere length (SL) and SHG intensity (SI) fluctuations. The fluctuations also revealed higher SHG intensity in elongated sarcomeres. The sarcomere synchronization model (SSM) for contracting and quiescent myocytes was developed, and experimentally verified for three cases (isolated cardiomyocyte, embryonic chicken cardiomyocyte, and larva myocyte). During contraction, the action of SLs and SIs between neighbouring sarcomeres partially correlated, whereas in quiescent myocytes the SLs show an anti-correlation and the SIs have no correlations. The characteristic correlation coefficients and amplitudes were obtained for each case, allowing for the characterization of the synchronization of sarcomere movement during muscle contraction. These investigations constitute the basis for studying the structure and physiology of muscle cell contractions with polarization SHG microscopy. Live dynamic imaging of myocytes is applicable for contractility research, drug discovery, and as a diagnostic tool for monitoring muscular diseases.

Pupil Dilation to Explicit and Non-Explicit Sexual Stimuli.

PubMed

Watts, Tuesday M; Holmes, Luke; Savin-Williams, Ritch C; Rieger, Gerulf

2017-01-01

Pupil dilation to explicit sexual stimuli (footage of naked and aroused men or women) can elicit sex and sexual orientation differences in sexual response. If similar patterns were replicated with non-explicit sexual stimuli (footage of dressed men and women), then pupil dilation could be indicative of automatic sexual response in fully noninvasive designs. We examined this in 325 men and women with varied sexual orientations to determine whether dilation patterns to non-explicit sexual stimuli resembled those to explicit sexual stimuli depicting the same sex or other sex. Sexual orientation differences in pupil dilation to non-explicit sexual stimuli mirrored those to explicit sexual stimuli. However, the relationship of dilation to non-explicit sexual stimuli with dilation to corresponding explicit sexual stimuli was modest, and effect magnitudes were smaller with non-explicit sexual stimuli than explicit sexual stimuli. The prediction that sexual orientation differences in pupil dilation are larger in men than in women was confirmed with explicit sexual stimuli but not with non-explicit sexual stimuli.

Malignant Esophagogastric Junction Obstruction: Efficacy of Balloon Dilation Combined with Chemotherapy and/or Radiation Therapy

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

Ko, Gi-Young; Song, Ho-Young, E-mail: hysong@amc.seoul.kr; Hong, Heuk-Jin

2003-04-15

Purpose: To assess the efficacy of balloon dilation combined with chemotherapy and/or radiation therapy for palliation of dysphagia due to malignant esophagogastric junction strictures. Methods: Fluoroscopically guided balloon dilation was attempted in 20 patients. The causes of strictures were gastric adenocarcinoma (n = 10) and esophageal squamous cell carcinoma (n = 10). Scheduled chemotherapy and/or radiation therapy followed balloon dilation in all patients. Results: There were no technical failures or major complications. After balloon dilation, 15 (75%) patients showed improvement of dysphagia. No patient complained of reflux esophagitis during the follow-up period. Among the 15 patients, seven needed no furthermore » treatment for palliation of dysphagia until their deaths. The remaining eight patients underwent repeat balloon dilation(n = 4) or stent placement (n = 4)3-43 weeks (mean 15 weeks) after the initial balloon dilation because of recurrent dysphagia. Conclusion: Balloon dilation combined with chemotherapy and/or radiation therapy seems to be an easy and reasonably effective palliative treatment for malignant esophagogastric strictures.« less

A prosthesis for banding the main pulmonary artery, capable of serial dilatation by balloon angioplasty.

PubMed

Vince, D J; Culham, J A

1989-03-01

A prosthesis constructed with a fatigued steel helix encased in a silicone rubber shield was used to band the main pulmonary artery in 10 dogs. After a mean duration of 138 days the banded site was dilated with a 20 mm diameter angioplasty catheter. This dilatation produced a mean increase of 44.3% in the cross-sectional area. A further mean increase of 2.2% in the cross-sectional area was measured 137 days after the dilatation. In five uncomplicated experiments a second dilatation was performed with a 23 mm diameter angioplasty catheter after a mean interval of 140 days. The second dilatation produced a further 21% increase in the cross-sectional area. In the five experiments in which two dilatations were performed, there was a total increase in the mean cross-sectional area of 94% produced 273 days after banding. This prosthesis maintains banding of the main pulmonary artery and can be serially dilated by balloon angioplasty.

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

Lee, Woong Hee; Kim, Jin Hyoung, E-mail: m1fenew@daum.net; Park, Jung-Hun

Purpose: Little was known about the safety and long-term efficacy of fluoroscopically guided balloon dilation for postintubation tracheal stenosis. The purpose of this study was to evaluate the safety and long-term efficacy of fluoroscopically guided balloon dilation in patients with postintubation tracheal stenosis. Methods: From February 2000 to November 2010, 14 patients underwent fluoroscopically guided balloon dilation for postintubation tracheal stenosis. Technical success, clinical success, and complications were evaluated. Patients were followed up for recurrent symptoms. Results: In all patients, fluoroscopically guided balloon dilation was technically and clinically successful with no major complications. Following the initial procedure, six patients (43more » %) remained asymptomatic during a follow-up period. Obstructive symptoms recurred in eight patients (57 %) within 6 months (mean, 1.7 months), who were treated with repeat balloon dilation (n = 4) and other therapies. Of the four patients who underwent repeat balloon dilation, three became asymptomatic. One patient became asymptomatic after a third balloon dilation. On long-term (mean, 74 months) follow-up, 71 % of patients experienced relief of symptoms following fluoroscopically guided balloon dilation. Conclusions: Fluoroscopically guided balloon dilation may be safe, is easy to perform, and resulted in effective treatment in patients with postintubation tracheal stenosis.« less

Dilatation of aortic grafts over time: what to expect and when to be concerned.

PubMed

Schroeder, Torben V; Eldrup, Nikolaj; Just, Sven; Hansen, Marc; Nyhuus, Bo; Sillesen, Henrik

2009-06-01

Dilatation of aortic prosthetic grafts is commonly reported, but most reports are anecdotal, with little objective data in the literature. We performed a prospective trial of 303 patients who underwent prosthetic graft repair for aortic aneurysm or occlusive disease, randomizing patients between insertion of a woven polyester or expanded polytetrafluoroethylene (ePTFE) graft. Patients were followed with computed tomography and ultrasonography for up to 5 years in order to assess the frequency and magnitude of postoperative dilatation. Graft dilatation was documented in patients with polyester grafts at 12 months. Thereafter and up to 60 months, polyester grafts did not dilate further. After 5 years, polyester prostheses had dilated by 25% and ePTFE by 12.5%, as determined by computed tomography imaging. These observations suggest that dilatation of prosthetic grafts is more frequent with knitted polyester grafts compared with ePTFE. Dilatation occurs within the first year after implantation and can be, in part, explained by a discrepancy between the initial nominal graft diameter and its diameter after clamp release, probably due to an in vivo adaptation of the textile structure. Interestingly, graft dilatation did not appear to be associated with an increased frequency of graft-related complications.

Psoriasis and dilated cardiomyopathy: coincidence or associated diseases?

PubMed

Eliakim-Raz, Noa; Shuvy, Mony; Lotan, Chaim; Planer, David

2008-01-01

Psoriasis is a common immune-mediated disease which affects 1-3% of the population. The etiology of psoriasis is unknown. Idiopathic dilated cardiomyopathy is probably the end result of a variety of toxic, metabolic or infectious agents. During a computerized search for cardiomyopathy among all patients hospitalized with psoriasis in the Hadassah University Hospital since 1980 we found an increased prevalence of cardiomyopathy, and specifically dilated cardiomyopathy. We present 4 patients who suffer from both conditions. In accordance with previous data, an association between preexisting psoriasis and dilated cardiomyopathy is suggested. We suggest that the genetic risk factors of dilated cardiomyopathy are shared by psoriasis, and more specifically psoriatic arthritis. Alternatively, the immune reaction that is triggered in dilated cardiomyopathy leading to the progression of the disease might be enhanced in patients with psoriasis or psoriatic arthritis. Chronic inflammation and persistent secretion of proinflammatory cytokines may be considered a potential pathway, triggering the initiation and progression of dilated cardiomyopathy in psoriatic patients. Further investigation of the genetic and immune risk factors involved in dilated cardiomyopathy and in psoriasis may lead to a better understanding of the pathogenesis and treatment of dilated cardiomyopathy. Copyright 2008 S. Karger AG, Basel.

Fluoroscopically guided large balloon dilatation for treating congenital esophageal stenosis in children.

PubMed

Hu, Hong-Tao; Shin, Ji Hoon; Kim, Jin-Hyoung; Jang, Jong Keon; Park, Jung-Hoon; Kim, Tae-Hyung; Nam, Deok Ho; Song, Ho-Young

2015-07-01

We aimed to evaluate the safety and clinical effectiveness of fluoroscopically guided large balloon dilatation for treating congenital esophageal stenosis in children. Our study included seven children (mean age 4.0 years) who underwent a total of ten balloon dilatation sessions. The initial balloon diameters were 10-15 mm. The technical success, clinical success (improved food intake and reduced dysphagia within 1 month following the first balloon dilatation), dysphagia recurrence, and complications were retrospectively evaluated. Technical and clinical success rates were 100 %. During the mean 38-month follow-up period after the first balloon dilatation, 3 (43 %) patients underwent only one additional balloon dilatation 4-5 months after the first balloon dilatation for dysphagia recurrence. Two of them showed improvement without further recurrence, while the remaining one underwent partial esophagectomy. Well-contained transmural esophageal rupture (type 2) occurred in two (29 %, 2/7) patients and during two (20 %, 2/10) balloon dilatation sessions. All ruptures were successfully treated conservatively. Our study showed that fluoroscopically guided large balloon dilatation seems to be a simple and effective primary treatment technique for congenital esophageal stenosis in children. Esophageal ruptures were not uncommon although they were not fatal.

Snare-assisted anterograde balloon mitral and aortic valvotomy using Inoue balloon catheter.

PubMed

Krishnan, Mangalath N; Syamkumar, M D; Sajeev, C G; Venugopal, K; Johnson, Francis; Vinaykumar, D; Velayudhan, C C; Jayakumar, T G

2007-01-02

We performed concurrent antegrade mitral and aortic valvotomy using Inoue dilatation catheter in 3 cases of combined rheumatic mitral and aortic stenosis. Following mitral valvotomy by standard procedure, aortic valve was crossed with the help of a floatation catheter. Stiff long length guide wire was fixed in descending aorta using a snare. Inoue catheter was threaded over the wire across the aortic valve and aortic valvotomy completed. Mitral valve area increased from mean 1 cm2 to 2 cm2; aortic gradient dropped from mean of 97 mm to 36 mm. Concurrent anterograde balloon mitral and aortic valvotomy may be effective and safe.

Sonographic evaluation of the bladder neck in continent and stress-incontinent women.

PubMed

Schaer, G N; Perucchini, D; Munz, E; Peschers, U; Koechli, O R; Delancey, J O

1999-03-01

To evaluate a new sonographic method to measure depth and width of proximal urethral dilation during coughing and Valsalva maneuver and to report its use in a group of stress-incontinent and continent women. Fifty-eight women were evaluated, 30 with and 28 without stress incontinence proven urodynamically, with a bladder volume of 300 mL and the subjects upright. Urethral pressure profiles at rest were performed with a 10 French microtip pressure catheter. Bladder neck dilation and descent were assessed by perineal ultrasound (5 MHz curved linear array transducer) with the help of ultrasound contrast medium (galactose suspension-Echovist-300), whereas abdominal pressure was assessed with an intrarectal balloon catheter. Statistical analysis used the nonparametric Mann-Whitney test. The depth and diameter of urethral dilation could be measured in all women. During Valsalva, all 30 incontinent women exhibited urethral dilation. One incontinent woman showed dilation only while performing a Valsalva maneuver, not during coughing. In the continent group, 12 women presented dilation during Valsalva and six during coughing. In continent women, dilation was visible only in those who were parous. Nulliparous women did not have dilation during Valsalva or coughing. Bladder neck descent was visible in continent and incontinent women. This method permits quantification of depth and diameter of bladder neck dilation, showing that both incontinent and continent women might have bladder neck dilation and that urinary continence can be established at different locations along the urethra in different women. Parity seems to be a main prerequisite for a proximal urethral defect with bladder neck dilation.

Isometric contractions of motor units in a fast twitch muscle of the cat

PubMed Central

Bagust, J.; Knott, Sarah; Lewis, D. M.; Luck, J. C.; Westerman, R. A.

1973-01-01

1. Isosmetric contractions of cat flexor digitorum longus whole muscles and of functionally isolated motor units have been measured under conditions similar to those used by Buller & Lewis (1965a). 2. Motor unit twitch time to peak was inversely related to axonal conduction velocity. The logarithm of tetanic tension was directly related to conduction velocity. These relationships suggest that each motoneurone has an influence on the muscle fibres which it innervates. 3. The ratio of twitch to tetanic tension was directly related to the time to peak of the motor unit. This fact might be explained by variation between motor units of the duration of `active state'. 4. The muscle length at which tension was maximal varied between motor units and the optima were found over the range of muscle lengths which could occur in the body. Slow motor units had longer optimal lengths. 5. The sample of motor units was considered to be unbiased because the distribution of axon conduction velocities was compatible with reported motor fibre diameter spectra of the muscle nerve. The mean motor unit tetanic tension gave a reasonable estimate of the number of α-motor axons in the muscle nerve. Twitch tensions gave a value that was 40% higher. 6. Motor unit and whole muscle data were in good agreement for length-tetanus tension curves, for times to peak and for twitch-tetanus ratios at long muscle lengths. PMID:4715372

Mechanisms of mechanical strain memory in airway smooth muscle.

PubMed

Kim, Hak Rim; Hai, Chi-Ming

2005-10-01

We evaluated the hypothesis that mechanical deformation of airway smooth muscle induces structural remodeling of airway smooth muscle cells, thereby modulating mechanical performance in subsequent contractions. This hypothesis implied that past experience of mechanical deformation was retained (or "memorized") as structural changes in airway smooth muscle cells, which modulated the cell's subsequent contractile responses. We termed this phenomenon mechanical strain memory. Preshortening has been found to induce attenuation of both force and isotonic shortening velocity in cholinergic receptor-activated airway smooth muscle. Rapid stretching of cholinergic receptor-activated airway smooth muscle from an initial length to a final length resulted in post-stretch force and myosin light chain phosphorylation that correlated significantly with initial length. Thus post-stretch muscle strips appeared to retain memory of the initial length prior to rapid stretch (mechanical strain memory). Cytoskeletal recruitment of actin- and integrin-binding proteins and Erk 1/2 MAPK appeared to be important mechanisms of mechanical strain memory. Sinusoidal length oscillation led to force attenuation during oscillation and in subsequent contractions in intact airway smooth muscle, and p38 MAPK appeared to be an important mechanism. In contrast, application of local mechanical strain to cultured airway smooth muscle cells induced local actin polymerization and cytoskeletal stiffening. It is conceivable that deep inspiration-induced bronchoprotection may be a manifestation of mechanical strain memory such that mechanical deformation from past breathing cycles modulated the mechanical performance of airway smooth muscle in subsequent cycles in a continuous and dynamic manner.

The tail sheath structure of bacteriophage T4: a molecular machine for infecting bacteria

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

Aksyuk, Anastasia A.; Leiman, Petr G.; Kurochkina, Lidia P.

2009-07-22

The contractile tail of bacteriophage T4 is a molecular machine that facilitates very high viral infection efficiency. Its major component is a tail sheath, which contracts during infection to less than half of its initial length. The sheath consists of 138 copies of the tail sheath protein, gene product (gp) 18, which surrounds the central non-contractile tail tube. The contraction of the sheath drives the tail tube through the outer membrane, creating a channel for the viral genome delivery. A crystal structure of about three quarters of gp18 has been determined and was fitted into cryo-electron microscopy reconstructions of themore » tail sheath before and after contraction. It was shown that during contraction, gp18 subunits slide over each other with no apparent change in their structure.« less

High-current discharge channel contraction in high density gas

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

Rutberg, Ph. G.; Bogomaz, A. A.; Pinchuk, M. E.

Research results for discharges at current amplitudes of 0.5-1.6 MA and current rise rate of {approx}10{sup 10} A/s are presented. The discharge is performed in the hydrogen environment at the initial pressure of 5-35 MPa. Initiation is implemented by a wire explosion. The time length of the first half-period of the discharge current is 70-150 {mu}s. Under such conditions, discharge channel contraction is observed; the contraction is followed by soft x-ray radiation. The phenomena are discussed, which are determined by high density of the gas surrounding the discharge channel. These phenomena are increase of the current critical value, where themore » channel contraction begins and growth of temperature in the axis region of the channel, where the initial density of the gas increases.« less

Traumatic tracheobronchial stricture treated with the Eder-Puestow dilator.

PubMed

Erichsen, H G

1980-09-01

A case of tracheobronchial stenosis secondary to trauma is presented. Primary reconstruction resulted in stricture in the distal part of the trachea. Resection and anastomosis was followed by restenosis, which had to be treated endoscopically. Endobronchial resections and forceful dilatations with stiff bronchoscopes were done weekly for about 11 months without lasting benefit. After changing to Eder-Puestow dilators, the dilatations could be done at steadily increasing intervals. This method of dilatation was found to be safe, effective and less traumatic.

Motor units in the human medial gastrocnemius muscle are not spatially localized or functionally grouped.

PubMed

Héroux, Martin E; Brown, Harrison J; Inglis, J Timothy; Siegmund, Gunter P; Blouin, Jean-Sébastien

2015-08-15

Human medial gastrocnemius (MG) motor units (MUs) are thought to occupy small muscle territories or regions, with low-threshold units preferentially located distally. We used intramuscular recordings to measure the territory of muscle fibres from MG MUs and determine whether these MUs are grouped by recruitment threshold or joint action (ankle plantar flexion and knee flexion). The territory of MUs from the MG muscle varied from somewhat localized to highly distributed, with approximately half the MUs spanning at least half the length and width of the muscle. There was also no evidence of regional muscle activity based on MU recruitment thresholds or joint action. The CNS does not have the means to selectively activate regions of the MG muscle based on task requirements. Human medial gastrocnemius (MG) motor units (MUs) are thought to occupy small muscle territories, with low-threshold units preferentially located distally. In this study, subjects (n = 8) performed ramped and sustained isometric contractions (ankle plantar flexion and knee flexion; range: ∼1-40% maximal voluntary contraction) and we measured MU territory size with spike-triggered averages from fine-wire electrodes inserted along the length (seven electrodes) or across the width (five electrodes) of the MG muscle. Of 69 MUs identified along the length of the muscle, 32 spanned at least half the muscle length (≥ 6.9 cm), 11 of which spanned all recording sites (13.6-17.9 cm). Distal fibres had smaller pennation angles (P < 0.05), which were accompanied by larger territories in MUs with fibres located distally (P < 0.05). There was no distal-to-proximal pattern of muscle activation in ramp contraction (P = 0.93). Of 36 MUs identified across the width of the muscle, 24 spanned at least half the muscle width (≥ 4.0 cm), 13 of which spanned all recording sites (8.0-10.8 cm). MUs were not localized (length or width) based on recruitment threshold or contraction type, nor was there a relationship between MU territory size and recruitment threshold (Spearman's rho = -0.20 and 0.13, P > 0.18). MUs in the human MG have larger territories than previously reported and are not localized based on recruitment threshold or joint action. This indicates that the CNS does not have the means to selectively activate regions of the MG muscle based on task requirements. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

30 CFR 206.53 - How do I determine value for oil that I or my affiliate do(es) not sell under an arm's-length...

Code of Federal Regulations, 2010 CFR

2010-07-01

..., from the property where it is produced to the point where you or your affiliate purchase(s) it. You may..., for purchases or sales under arm's-length contracts. (1) When calculating that unit value, use only purchases or sales of other like-quality oil produced from the field (or the same area if you do not have...

Stimulation of respiratory changes in alae nasi length by chemoreceptor activation.

PubMed

Van Lunteren, E; Haxhiu, M A; Cherniack, N S

1986-03-01

Respiratory-related changes in length of the nasal dilator muscle, the alae nasi muscle, were measured using sonomicrometry in ten anesthetized (pentobarbital), tracheostomized, spontaneously breathing dogs. Piezoelectric crystals were inserted 7-25 mm apart along the direction of the alae nasi muscle fibers, and the effects of progressive hyperoxic hypercapnia and a peripheral and central chemoreceptor stimulant, nicotine (10-500 micrograms intravenously), were ascertained. The alae nasi shortened during inspiration in all animals, started to lengthen again towards the end of inspiration, returned to resting length during the first portion of expiration (Te-1), and remained at resting length for the remainder of expiration (Te-2). The amount of alae nasi inspiratory shortening was increased by occluding the airway for a single breath. Progressive hypercapnia caused progressive increases in the amount and velocity of nasal muscle inspiratory shortening during both unoccluded and occluded breaths; similar stimulatory effects on inspiratory shortening were seen following nicotine administration. Furthermore, both chemoreceptor stimulants caused a delay in the return of the muscle to its resting length during expiration, resulting in a significant increase in Te-1 relative to Te (Te-1/Te), and a greater amount of nasal muscle shortening to be present during Te-1. In some animals these agents also caused tonic shortening of the alae nasi, so that the muscle never returned to its resting length. These results suggest that inspiratory shortening of the alae nasi is inhibited by vagal inputs, but that chemoreceptor activation increases the amount of muscle shortening during both inspiration and early expiration.

Dilatancy Criteria for Salt Cavern Design: A Comparison Between Stress- and Strain-Based Approaches

NASA Astrophysics Data System (ADS)

Labaune, P.; Rouabhi, A.; Tijani, M.; Blanco-Martín, L.; You, T.

2018-02-01

This paper presents a new approach for salt cavern design, based on the use of the onset of dilatancy as a design threshold. In the proposed approach, a rheological model that includes dilatancy at the constitutive level is developed, and a strain-based dilatancy criterion is defined. As compared to classical design methods that consist in simulating cavern behavior through creep laws (fitted on long-term tests) and then using a criterion (derived from short-terms tests or experience) to determine the stability of the excavation, the proposed approach is consistent both with short- and long-term conditions. The new strain-based dilatancy criterion is compared to a stress-based dilatancy criterion through numerical simulations of salt caverns under cyclic loading conditions. The dilatancy zones predicted by the strain-based criterion are larger than the ones predicted by the stress-based criteria, which is conservative yet constructive for design purposes.

Effects of delayed pushing during the second stage of labor on postpartum fatigue and birth outcomes in nulliparous women.

PubMed

Lai, Man-Lung; Lin, Kuan-Chia; Li, Hsin Yang; Shey, Kuang-Shing; Gau, Meei-Ling

2009-03-01

This article studied differences in postpartum fatigue and birth outcomes between women who pushed immediately and those who delayed pushing during the second stage of labor. Data were collected from primiparous women in their 38th to 42nd gestational week who did not receive epidural analgesia during labor and were free of complications during pregnancy. Using a quasi-experimental design, 72 participants selected by convenient sampling were assigned based on individual participant's preference to either an experimental or control group. For the experimental group, pushing was delayed until the point after full cervical dilation at which (a) the mother felt a strong physical pushing reflex, (b) the fetal head had both descended to at least the +1 level in the pelvis and turned to the occiput anterior position, and (c) uterine contractions were at least 30 mmHg. For the control group, the physician instructed mothers to begin pushing after full cervical dilation at the point when the fetal head was in the occiput anterior position and uterine contractions were at least 30 mmHg. The authors administered the Modified Fatigue Symptom Checklist at 1 and 24 hr after delivery to measure participant's fatigue levels. Birth outcomes were assessed based on medical chart data. Findings showed a significant difference between the two groups in terms of 1- and 24-hr postpartum fatigue scores. The duration of the second labor stage (experimental group, 70.31 +/- 37.17 min; control group, 129.06 +/- 75.69 min) also differed significantly. The group that pushed immediately recorded higher cesarean and instrument-assisted birth rates. No significant differences were observed in terms of perineal tears, maternal/neonatal complications, or neonatal Apgar scores. Results of this study provide important insights for caregivers working in the delivery room and suggest that current care procedures change to include the delayed pushing during the second stage of labor. By delaying pushing exertions until the mother feels a reflexive urge to do so, mothers' feelings of fatigue are significantly reduced.

Focal dilation and paradoxical collapse of cortical fissures and sulci in patients with normal-pressure hydrocephalus.

PubMed

Holodny, A I; George, A E; de Leon, M J; Golomb, J; Kalnin, A J; Cooper, P R

1998-11-01

The authors describe a subgroup of patients with shunt-proven normal-pressure hydrocephalus (NPH) who presented with focal fissural and sulcal dilation on imaging studies. The specific radiological features and methods of differentiating this condition from cortical atrophy are delineated. Normal-pressure hydrocephalus has been described as dilation of the ventricles that is out of proportion to the sulci. Sulcal dilation has been taken as evidence of cortical atrophy and has even been used as a criterion to exclude patients from undergoing a shunting procedure. The authors describe five cases of patients with shunt-proven NPH who presented with focal dilation of cortical fissures and sulci. In three of the cases, there was a paradoxical decrease in the size of the dilated fissures and sulci that paralleled the decrease in the size of the lateral ventricles following successful shunting. This study demonstrates that focal fissural and sulcal dilation may represent reservoirs of cerebrospinal fluid analogous to the ventricular system. Patients should not be denied a shunting procedure solely on the basis of focally dilated fissures of sulci.

Mass transfer effect of the stalk contraction-relaxation cycle of Vorticella convallaria

NASA Astrophysics Data System (ADS)

Zhou, Jiazhong; Admiraal, David; Ryu, Sangjin

2014-11-01

Vorticella convallaria is a genus of protozoa living in freshwater. Its stalk contracts and coil pulling the cell body towards the substrate at a remarkable speed, and then relaxes to its extended state much more slowly than the contraction. However, the reason for Vorticella's stalk contraction is still unknown. It is presumed that water flow induced by the stalk contraction-relaxation cycle may augment mass transfer near the substrate. We investigated this hypothesis using an experimental model with particle tracking velocimetry and a computational fluid dynamics model. In both approaches, Vorticella was modeled as a solid sphere translating perpendicular to a solid surface in water. After having been validated by the experimental model and verified by grid convergence index test, the computational model simulated water flow during the cycle based on the measured time course of stalk length changes of Vorticella. Based on the simulated flow field, we calculated trajectories of particles near the model Vorticella, and then evaluated the mass transfer effect of Vorticella's stalk contraction based on the particles' motion. We acknowlege support from Laymann Seed Grant of the University of Nebraska-Lincoln.

[Endoscopic contribution in the dilatation of caustic esophagus stenosis].

PubMed

Seydou, Togo; Abdoulaye, Ouattara Moussa; Xing, Li; Zi, Sanogo Zimogo; Sekou, Koumaré; Wen, Yang Shang; Ibrahim, Sankare; Sekou, Toure Cheik Ahmed; Boubacar, Maiga Ibrahim; Saye, Jacque; Jerome, Dakouo Dodino; Dantoumé, Toure Ousmane; Sadio, Yena

2016-01-01

The aim of this work was to present the contribution of the endoscopy in the management of esophageal dilatation for caustic esophageal stenosis (CES). This was a descriptive and prospective study in the thoracic surgery department at the Hospital of Mali. A total of 46 cases of CES is recorded and divided into 4 groups according to the topography of the esophageal lesions. For the different methods of dilatation the number of performed endoscopic support was determined to understand the contribution of endoscopic means in the success of dilatation for CES. The outcome, complications and mortality in the two methods were compared. Fibroscopy was used in 41.30% of patients with Savary Guillard dilators and in 47.82% of patients with Lerut dilators. Video laryngoscopy was used in 58.69% of patients who underwent dilatation with Lerut dilators. The passage of the guide wire was performed in 39.13% under video laryngoscopy and 58.68% under fibroscopy. In comparison of the two methods, there is a significant difference in the occurrence of complications (p=0.04075), general anesthesia (p=0.02287), accessibility (p=0.04805) and mortality (p=0.00402). The CES is a serious disease and under evaluated in Mali. The endoscopies contribute significantly to the success of esophageal dilatation for caustic stenosis in the different methods we used.

A comparison among four tract dilation methods of percutaneous nephrolithotomy: a systematic review and meta-analysis.

PubMed

Dehong, Cao; Liangren, Liu; Huawei, Liu; Qiang, Wei

2013-11-01

The purpose of this study was to evaluate the efficacy and safety of the Amplatz dilation (AD), metal telescopic dilation (MTD), balloon dilation (BD), and one-shot dilation (OSD) methods for tract dilation during percutaneous nephrolithotomy (PCNL). Relevant eligible studies were identified using three electronic databases (Medline, EMBASE, and Cochrane CENTRAL). Database acquisition and quality evaluation were independently performed by two reviewers. Efficacy (stone-free rate, surgical duration, and tract dilatation fluoroscopy time) and safety (transfusion rate and hemoglobin decrease) were evaluated using Review Manager 5.2. Four randomized controlled trials and eight clinical controlled trials involving 6,820 patients met the inclusion criteria. The pooled result from a meta-analysis showed statistically significant differences in tract dilatation fluoroscopy time and hemoglobin decrease between the OSD and MTD groups, which showed comparable stone-free and transfusion rates. Significant differences in transfusion rate were found between the BD and MTD groups. Among patients without previous open renal surgery, those who underwent BD exhibited a lower blood transfusion rate and a shorter surgical duration compared with those who underwent AD. The OSD technique is safer and more efficient than the MTD technique for tract dilation during PCNL, particularly in patients with previous open renal surgery, resulting in a shorter tract dilatation fluoroscopy time and a lesser decrease in hemoglobin. The efficacy and safety of BD are better than AD in patients without previous open renal surgery. The OSD technique should be considered for most patients who undergo PCNL therapy.

Health-Care Utilization and Complications of Endoscopic Esophageal Dilation in a National Population

PubMed Central

Goyal, Abhinav; Chatterjee, Kshitij; Yadlapati, Sujani; Singh, Shailender

2017-01-01

Background/Aims Esophageal stricture is usually managed with outpatient endoscopic dilation. However, patients with food impaction or failure to thrive undergo inpatient dilation. Esophageal perforation is the most feared complication, and its risk in inpatient setting is unknown. Methods We used National Inpatient Sample (NIS) database for 2007–2013. International Classification of Diseases, 9th revision, Clinical Modification (ICD-9-CM) codes were used to identify patients with esophageal strictures. Logistic regression was used to assess association between hospital/patient characteristics and utilization of esophageal dilation. Results There were 591,187 hospitalizations involving esophageal stricture; 4.2% were malignant. Endoscopic dilation was performed in 28.7% cases. Dilation was more frequently utilized (odds ratio [OR], 1.36; p<0.001), had higher in-hospital mortality (3.1% vs. 1.4%, p<0.001), and resulted in longer hospital stays (5 days vs. 4 days, p=0.01), among cases of malignant strictures. Esophageal perforation was more common in the malignant group (0.9% vs. 0.5%, p=0.007). Patients with malignant compared to benign strictures undergoing dilation were more likely to require percutaneous endoscopic gastrostomy or jejunostomy (PEG/J) tube (14.1% vs. 4.5%, p<0.001). Palliative care services were utilized more frequently in malignant stricture cases not treated with dilation compared to those that were dilated. Conclusions Inpatient endoscopic dilation was utilized in 29% cases of esophageal stricture. Esophageal perforation, although infrequent, is more common in malignant strictures. PMID:28301921

Fractal feature of sEMG from Flexor digitorum superficialis muscle correlated with levels of contraction during low-level finger flexions.

PubMed

Arjunan, Sridhar P; Kumar, Dinesh K; Naik, Ganesh R

2010-01-01

This research paper reports an experimental study on identification of the changes in fractal properties of surface Electromyogram (sEMG) with the changes in the force levels during low-level finger flexions. In the previous study, the authors have identified a novel fractal feature, Maximum fractal length (MFL) as a measure of strength of low-level contractions and has used this feature to identify various wrist and finger movements. This study has tested the relationship between the MFL and force of contraction. The results suggest that changes in MFL is correlated with the changes in contraction levels (20%, 50% and 80% maximum voluntary contraction (MVC)) during low-level muscle activation such as finger flexions. From the statistical analysis and by visualisation using box-plot, it is observed that MFL (p ≈ 0.001) is a more correlated to force of contraction compared to RMS (p≈0.05), even when the muscle contraction is less than 50% MVC during low-level finger flexions. This work has established that this fractal feature will be useful in providing information about changes in levels of force during low-level finger movements for prosthetic control or human computer interface.

Trainability of Muscular Activity Level during Maximal Voluntary Co-Contraction: Comparison between Bodybuilders and Nonathletes

PubMed Central

Maeo, Sumiaki; Takahashi, Takumi; Takai, Yohei; Kanehisa, Hiroaki

2013-01-01

Antagonistic muscle pairs cannot be fully activated simultaneously, even with maximal effort, under conditions of voluntary co-contraction, and their muscular activity levels are always below those during agonist contraction with maximal voluntary effort (MVE). Whether the muscular activity level during the task has trainability remains unclear. The present study examined this issue by comparing the muscular activity level during maximal voluntary co-contraction for highly experienced bodybuilders, who frequently perform voluntary co-contraction in their training programs, with that for untrained individuals (nonathletes). The electromyograms (EMGs) of biceps brachii and triceps brachii muscles during maximal voluntary co-contraction of elbow flexors and extensors were recorded in 11 male bodybuilders and 10 nonathletes, and normalized to the values obtained during the MVE of agonist contraction for each of the corresponding muscles (% EMGMVE). The involuntary coactivation level in antagonist muscle during the MVE of agonist contraction was also calculated. In both muscles, % EMGMVE values during the co-contraction task for bodybuilders were significantly higher (P<0.01) than those for nonathletes (biceps brachii: 66±14% in bodybuilders vs. 46±13% in nonathletes, triceps brachii: 74±16% vs. 57±9%). There was a significant positive correlation between a length of bodybuilding experience and muscular activity level during the co-contraction task (r = 0.653, P = 0.03). Involuntary antagonist coactivation level during MVE of agonist contraction was not different between the two groups. The current result indicates that long-term participation in voluntary co-contraction training progressively enhances muscular activity during maximal voluntary co-contraction. PMID:24260233

Randomized controlled trial comparing esophageal dilation to no dilation among adults with esophageal eosinophilia and dysphagia.

PubMed

Kavitt, R T; Ates, F; Slaughter, J C; Higginbotham, T; Shepherd, B D; Sumner, E L; Vaezi, M F

2016-11-01

The role of esophageal dilation in patients with esophageal eosinophilia with dysphagia remains unknown. The practice of dilation is currently based on center preferences and expert opinion. The aim of this study is to determine if, and to what extent, dysphagia improves in response to initial esophageal dilation followed by standard medical therapies. We conducted a randomized, blinded, controlled trial evaluating adult patients with dysphagia and newly diagnosed esophageal eosinophilia from 2008 to 2013. Patients were randomized to dilation or no dilation at time of endoscopy and blinded to dilation status. Endoscopic features were graded as major and minor. Subsequent to randomization and endoscopy, all patients received fluticasone and dexlansoprazole for 2 months. The primary study outcome was reduction in overall dysphagia score, assessed at 30 and 60 days post-intervention. Patients with severe strictures (less than 7-mm esophageal diameter) were excluded from the study. Thirty-one patients were randomized and completed the protocol: 17 randomized to dilation and 14 to no dilation. Both groups were similar with regard to gender, age, eosinophil density, endoscopic score, and baseline dysphagia score. The population exhibited moderate to severe dysphagia and moderate esophageal stricturing at baseline. Overall, there was a significant (P < 0.001) but similar reduction in mean dysphagia score at 30 and 60 days post-randomization compared with baseline in both groups. No significant difference in dysphagia scores between treatment groups after 30 (P = 0.93) or 60 (P = 0.21) days post-intervention was observed. Esophageal dilation did not result in additional improvement in dysphagia score compared with treatment with proton pump inhibitor and fluticasone alone. In patients with symptomatic esophageal eosinophilia without severe stricture, dilation does not appear to be a necessary initial treatment strategy. © 2015 International Society for Diseases of the Esophagus.

Nitroglycerin mediated dilation evaluated by ultrasound is associated with sTWEAK in hemodialysis patients.

PubMed

Rusu, Crina Claudia; Ghervan, Liviu; Racasan, Simona; Kacsa, Ina; Moldovan, Diana; Potra, Alina; Bondor, Cosmina; Anton, Florin; Patiu, Ioan Mihai; Caprioara, Mirela Gherman

2016-03-01

The main cause of death in hemodialysis (HD) patients is cardiovascular disease. Ultrasound assessment of the brachial artery dysfunction is easily achievable and can non-invasively detect atherosclerosis in various stages. In HD patients the cardiovascular risk profile is different and the determinants of brachial arterial function can be distinct comparing with general population. The aim of the study is to assess the determinants of arterial brachial function (flow-mediated and nitroglycerin-mediated dilation) evaluated by ultrasound in HD patients and their relation with tumor necrosis factor-like weak inducer of apoptosis (sTWEAK) described as atherosclerotic marker in chronic kidney disease patients. We conducted a cross-sectional observational study on 54 hemodialysis patients. We recorded clinical and biological data and we measured sTWEAK serum levels by ELISA. We evaluated the arterial brachial function by measurement of flow-mediated and nitroglycerin-mediated dilation, using B mode ultrasound. The determinants of flow-mediated dilation were: Kt/V (r=0.47, p<0.001), LDL-cholesterol (r=0.29, p=0.04), and total cholesterol (r=0.31, p=0.02). Flow-mediated dilation correlated with nitroglycerin-mediated dilation (r=0.70, p<0.001). In multivariate analysis kt/V was the only significant predictor for flow-mediated dilation (p=0.04). Nitroglycerin-mediated dilation correlates with sTWEAK (r=-0.30, p=0.03), systolic blood pressure (r=-0.28, p=0.04) and pulse pressure (r=-0.31, p=0.02). In multivariate analysis sTWEAK was the only significant predictor for nitroglycerin-mediated dilation (p=0.04). The main determinant of nitroglycerin-mediated dilation was sTWEAK. In addition, decreased nitroglycerin-mediated dilation was associated with higher systolic blood pressure and pulse pressure. The main determinant of FMD was Kt/V. Increased flow-mediated dilation was associated with better dialysis efficiency and high total cholesterol and LDL-cholesterol.

Hygroscopic dilators vs balloon catheter ripening of the cervix for induction of labor in nulliparous women at term: Retrospective study

PubMed Central

Shindo, Ryosuke; Yonemoto, Naohiro; Yamamoto, Yuriko; Kasai, Junko; Kasai, Michi; Miyagi, Etsuko

2017-01-01

Objective To compare the efficacy and safety of hygroscopic dilators and balloon catheters for ripening of the cervix in induction of labor. Study design This retrospective, observational study used data from the Successive Pregnancy Birth Registry System of the Japan Society of Obstetrics and Gynecology from 2012 to 2014. Nulliparous women in whom labor was induced by mechanical methods of cervical ripening at term were enrolled. The eligible women were divided into dilator, balloon <40 mL, balloon ≧40 mL, and overlapping groups. Results The groups included 4645, 4100, 6615, and 1992 women, respectively. In the overlapping group, which included the women in whom delivery was most difficult, the vaginal delivery rate was lower and the intrauterine infection and neonatal mortality rates were higher than those in the dilator group. No difference in the vaginal delivery rate was observed among the dilator, balloon <40 mL, and balloon ≧40 mL groups (74.6%, 72.3%, and 73.8%, respectively; p>0.05). The vaginal instrumental delivery rate was higher in the two-balloon groups than in the dilator group. The volume of intrapartum hemorrhage was lowest in the dilator group. No significant difference in the frequencies of uterine rupture and intrauterine infection were observed among the dilator and two-balloon groups. With regard to neonatal outcomes, the frequency of a low Apgar score was statistically significantly lower in the dilator group than in the two-balloon groups. Moreover, the frequency of neonatal death tended to be lower in the dilator group than in the two-balloon groups. Conclusion With regard to cervical ripening for labor induction in nulliparous women at term, the vaginal delivery rate on using a dilator and on using a balloon seems to be equivalent. Concerning maternal complications and neonatal outcomes, cervical ripening with hygroscopic dilators in labor induction might be safer. PMID:29272277

Cervical Length: Why Does It Matter during Pregnancy?

MedlinePlus

... frequent contractions, a constant low, dull backache, vaginal spotting, or pelvic pressure — your health care provider might ... trademarks of Mayo Foundation for Medical Education and Research. © 1998-2018 Mayo Foundation for Medical Education and ...

Intramuscular pressure and electromyography as indexes of force during isokinetic exercise

NASA Technical Reports Server (NTRS)

Aratow, M.; Ballard, R. E.; Grenshaw, A. G.; Styf, J.; Watenpaugh, D. E.; Kahan, N. J.; Hargens, A. R.

1993-01-01

A direct method for measuring force production of specific muscles during dynamic exercise is presently unavailable. Previous studies indicate that both intramuscular pressure (IMP) and electromyography (EMG) correlate linearly with muscle contraction force during isometric exercise. The objective of this study was to compare IMP and EMG as linear assessors of muscle contraction force during dynamic exercise. IMP and surface EMG activity were recorded during concentric and eccentric isokinetic plantarflexion and dorsiflexion of the ankle joint from the tibialis anterior (TA) and soleus (SOL) muscles of nine male volunteers. Ankle torque was measured using a dynamometer, and IMP was measured via catheterization. IMP exhibited better linear correlation than EMG with ankle joint torque during concentric contractions of the SOL and the TA, as well as during eccentric contractions. IMP provides a better index of muscle contraction force than EMG during concentric and eccentric exercise through the entire range of torque. IMP reflects intrinsic mechanical properties of individual muscles, such as length-tension relationships, which EMG is unable to assess.

The influence of confounding factors on the relationship between muscle contraction level and MF and MPF values of EMG signal: a review

PubMed Central

Roman-Liu, Danuta

2016-01-01

The purpose of this article is to gather results of studies on the relationship between median frequency (MF) and mean power frequency (MPF) and the level of muscle contraction, and to use those results to discuss the differences in the trends according to factors related to measurement technique and subject. Twenty-one studies with 63 cases for upper limb muscles and nine studies with 31 cases for lower limb muscles were analysed. Most results showed an increase in parameters with an increased level of muscle contraction, only some studies showed a decrease. The influence on parameters of the level of muscle contraction and factors such as subjects, type of contraction, muscle length and electrodes was analysed for each muscle. It was concluded that when analysing the influence of different factors on MF and MPF, because those factors interact they should be considered together, not separately. PMID:26654476

Work Done by Titin Protein Folding Assists Muscle Contraction.

PubMed

Rivas-Pardo, Jaime Andrés; Eckels, Edward C; Popa, Ionel; Kosuri, Pallav; Linke, Wolfgang A; Fernández, Julio M

2016-02-16

Current theories of muscle contraction propose that the power stroke of a myosin motor is the sole source of mechanical energy driving the sliding filaments of a contracting muscle. These models exclude titin, the largest protein in the human body, which determines the passive elasticity of muscles. Here, we show that stepwise unfolding/folding of titin immunoglobulin (Ig) domains occurs in the elastic I band region of intact myofibrils at physiological sarcomere lengths and forces of 6-8 pN. We use single-molecule techniques to demonstrate that unfolded titin Ig domains undergo a spontaneous stepwise folding contraction at forces below 10 pN, delivering up to 105 zJ of additional contractile energy, which is larger than the mechanical energy delivered by the power stroke of a myosin motor. Thus, it appears inescapable that folding of titin Ig domains is an important, but as yet unrecognized, contributor to the force generated by a contracting muscle. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Computation and evaluation of features of surface electromyogram to identify the force of muscle contraction and muscle fatigue.

PubMed

Arjunan, Sridhar P; Kumar, Dinesh K; Naik, Ganesh

2014-01-01

The relationship between force of muscle contraction and muscle fatigue with six different features of surface electromyogram (sEMG) was determined by conducting experiments on thirty-five volunteers. The participants performed isometric contractions at 50%, 75%, and 100% of their maximum voluntary contraction (MVC). Six features were considered in this study: normalised spectral index (NSM5), median frequency, root mean square, waveform length, normalised root mean square (NRMS), and increase in synchronization (IIS) index. Analysis of variance (ANOVA) and linear regression analysis were performed to determine the significance of the feature with respect to the three factors: muscle force, muscle fatigue, and subject. The results show that IIS index of sEMG had the highest correlation with muscle fatigue and the relationship was statistically significant (P < 0.01), while NSM5 associated best with level of muscle contraction (%MVC) (P < 0.01). Both of these features were not affected by the intersubject variations (P > 0.05).

Computation and Evaluation of Features of Surface Electromyogram to Identify the Force of Muscle Contraction and Muscle Fatigue

PubMed Central

Arjunan, Sridhar P.; Kumar, Dinesh K.; Naik, Ganesh

2014-01-01

The relationship between force of muscle contraction and muscle fatigue with six different features of surface electromyogram (sEMG) was determined by conducting experiments on thirty-five volunteers. The participants performed isometric contractions at 50%, 75%, and 100% of their maximum voluntary contraction (MVC). Six features were considered in this study: normalised spectral index (NSM5), median frequency, root mean square, waveform length, normalised root mean square (NRMS), and increase in synchronization (IIS) index. Analysis of variance (ANOVA) and linear regression analysis were performed to determine the significance of the feature with respect to the three factors: muscle force, muscle fatigue, and subject. The results show that IIS index of sEMG had the highest correlation with muscle fatigue and the relationship was statistically significant (P < 0.01), while NSM5 associated best with level of muscle contraction (%MVC) (P < 0.01). Both of these features were not affected by the intersubject variations (P > 0.05). PMID:24995275

Performance Contracting and Quality Improvement in Outpatient Treatment: Effects on Waiting Time and Length of Stay

PubMed Central

Stewart, Maureen T.; Horgan, Constance M.; Garnick, Deborah W.; Ritter, Grant; McLellan, A. Thomas

2012-01-01

We evaluate effects of a performance contract (PC) implemented in Delaware in 2001 and participation in quality improvement (QI) programs on waiting time for treatment and length of stay (LOS) using client treatment episode level data from Delaware (n = 12,368) and Maryland (n = 147,151) for 1998 – 2006. Results of difference-in-difference analyses indicate waiting time declined 13 days following the PC, after controlling for client characteristics and historical trends. Participation in the PC and a formal QI program was associated with a decrease of 20 days. LOS increased 22 days under the PC and 24 days under the PC and QI programs, after controlling for client characteristics. The PC and QI program were associated with improvements in LOS and waiting time, although we cannot determine which aspects of the programs (incentives, training, monitoring) resulted in these changes. PMID:22445031

Impaired activity of adherens junctions contributes to endothelial dilator dysfunction in ageing rat arteries.

PubMed

Chang, Fumin; Flavahan, Sheila; Flavahan, Nicholas A

2017-08-01

Ageing-induced endothelial dysfunction contributes to organ dysfunction and progression of cardiovascular disease. VE-cadherin clustering at adherens junctions promotes protective endothelial functions, including endothelium-dependent dilatation. Ageing increased internalization and degradation of VE-cadherin, resulting in impaired activity of adherens junctions. Inhibition of VE-cadherin clustering at adherens junctions (function-blocking antibody; FBA) reduced endothelial dilatation in young arteries but did not affect the already impaired dilatation in old arteries. After junctional disruption with the FBA, dilatation was similar in young and old arteries. Src tyrosine kinase activity and tyrosine phosphorylation of VE-cadherin were increased in old arteries. Src inhibition increased VE-cadherin at adherens junctions and increased endothelial dilatation in old, but not young, arteries. Src inhibition did not increase dilatation in old arteries treated with the VE-cadherin FBA. Ageing impairs the activity of adherens junctions, which contributes to endothelial dilator dysfunction. Restoring the activity of adherens junctions could be of therapeutic benefit in vascular ageing. Endothelial dilator dysfunction contributes to pathological vascular ageing. Experiments assessed whether altered activity of endothelial adherens junctions (AJs) might contribute to this dysfunction. Aortas and tail arteries were isolated from young (3-4 months) and old (22-24 months) F344 rats. VE-cadherin immunofluorescent staining at endothelial AJs and AJ width were reduced in old compared to young arteries. A 140 kDa VE-cadherin species was present on the cell surface and in TTX-insoluble fractions, consistent with junctional localization. Levels of the 140 kDa VE-cadherin were decreased, whereas levels of a TTX-soluble 115 kDa VE-cadherin species were increased in old compared to young arteries. Acetylcholine caused endothelium-dependent dilatation that was decreased in old compared to young arteries. Disruption of VE-cadherin clustering at AJs (function-blocking antibody, FBA) inhibited dilatation to acetylcholine in young, but not old, arteries. After the FBA, there was no longer any difference in dilatation between old and young arteries. Src activity and tyrosine phosphorylation of VE-cadherin were increased in old compared to young arteries. In old arteries, Src inhibition (saracatinib) increased: (i) 140 kDa VE-cadherin in the TTX-insoluble fraction, (ii) VE-cadherin intensity at AJs, (iii) AJ width, and (iv) acetylcholine dilatation. In old arteries treated with the FBA, saracatinib no longer increased acetylcholine dilatation. Saracatinib did not affect dilatation in young arteries. Therefore, ageing impairs AJ activity, which appears to reflect Src-induced phosphorylation, internalization and degradation of VE-cadherin. Moreover, impaired AJ activity can account for the endothelial dilator dysfunction in old arteries. Restoring endothelial AJ activity may be a novel therapeutic approach to vascular ageing. © 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.

Large increase in fracture resistance of stishovite with crack extension less than one micrometer

PubMed Central

Yoshida, Kimiko; Wakai, Fumihiro; Nishiyama, Norimasa; Sekine, Risako; Shinoda, Yutaka; Akatsu, Takashi; Nagoshi, Takashi; Sone, Masato

2015-01-01

The development of strong, tough, and damage-tolerant ceramics requires nano/microstructure design to utilize toughening mechanisms operating at different length scales. The toughening mechanisms so far known are effective in micro-scale, then, they require the crack extension of more than a few micrometers to increase the fracture resistance. Here, we developed a micro-mechanical test method using micro-cantilever beam specimens to determine the very early part of resistance-curve of nanocrystalline SiO2 stishovite, which exhibited fracture-induced amorphization. We revealed that this novel toughening mechanism was effective even at length scale of nanometer due to narrow transformation zone width of a few tens of nanometers and large dilatational strain (from 60 to 95%) associated with the transition of crystal to amorphous state. This testing method will be a powerful tool to search for toughening mechanisms that may operate at nanoscale for attaining both reliability and strength of structural materials. PMID:26051871

Impedance of strip-traveling waves on an elastic half space - Asymptotic solution

NASA Technical Reports Server (NTRS)

Crandall, S. H.; Nigam, A. K.

1973-01-01

The dynamic normal-load distribution across a strip that is required to maintain a plane progressive wave along its length is studied for the case where the strip is of infinite length and lies on the surface of a homogeneous isotropic elastic half space. This configuration is proposed as a preliminary idealized model for analyzing the dynamic interaction between soils and flexible foundations. The surface load distribution across the strip and the motion of the strip are related by a pair of dual integral equations. An asymptotic solution is obtained for the limiting case of small wavelength. The nature of this solution depends importantly on the propagation velocity of the strip-traveling wave in comparison with the Rayleigh wave speed, the shear wave speed and the dilatational wave speed. When the strip-traveling wave propagates faster than the Rayleigh wave speed, a pattern of trailing Rayleigh waves is shed from the strip. The limiting amplitude of the trailing waves is provided by the asymptotic solution.

The impact law of confining pressure and plastic parameter on Dilatancy of rock

NASA Astrophysics Data System (ADS)

Wang, Bin; Zhang, Zhenjie; Zhu, Jiebing

2017-08-01

Based on cyclic loading-unloading triaxle test of marble, the double parameter dilation angle model is established considering confining pressure effect and plastic parameter. Research shows that not only the strength but also the militancy behavior is highly depended on its confining pressure and plastic parameter during process of failure. Dilation angle evolution law shows obvious nonlinear characteristic almost with a rapid increase to the peak and then decrease gradually with plastic increasing, and the peak dilation angle value is inversely proportional with confining pressure. The proposed double parameter nonlinear dilation angle model can be used to well describe the Dilatancy of rock, which helps to understand the failure mechanism of surrounding rock mass and predict the range of plastic zone.

In-Vivo Measurement of Muscle Tension: Dynamic Properties of the MC Sensor during Isometric Muscle Contraction

PubMed Central

Đorđević, Srđan; Tomažič, Sašo; Narici, Marco; Pišot, Rado; Meglič, Andrej

2014-01-01

Skeletal muscle is the largest tissue structure in our body and plays an essential role for producing motion through integrated action with bones, tendons, ligaments and joints, for stabilizing body position, for generation of heat through cell respiration and for blood glucose disposal. A key function of skeletal muscle is force generation. Non-invasive and selective measurement of muscle contraction force in the field and in clinical settings has always been challenging. The aim of our work has been to develop a sensor that can overcome these difficulties and therefore enable measurement of muscle force during different contraction conditions. In this study, we tested the mechanical properties of a “Muscle Contraction” (MC) sensor during isometric muscle contraction in different length/tension conditions. The MC sensor is attached so that it indents the skin overlying a muscle group and detects varying degrees of tension during muscular contraction. We compared MC sensor readings over the biceps brachii (BB) muscle to dynamometric measurements of force of elbow flexion, together with recordings of surface EMG signal of BB during isometric contractions at 15° and 90° of elbow flexion. Statistical correlation between MC signal and force was very high at 15° (r = 0.976) and 90° (r = 0.966) across the complete time domain. Normalized SD or σN = σ/max(FMC) was used as a measure of linearity of MC signal and elbow flexion force in dynamic conditions. The average was 8.24% for an elbow angle of 90° and 10.01% for an elbow of angle 15°, which indicates high linearity and good dynamic properties of MC sensor signal when compared to elbow flexion force. The next step of testing MC sensor potential will be to measure tension of muscle-tendon complex in conditions when length and tension change simultaneously during human motion. PMID:25256114

Decrease in coronary vascular volume in systole augments cardiac contraction.

PubMed

Willemsen, M J; Duncker, D J; Krams, R; Dijkman, M A; Lamberts, R R; Sipkema, P; Westerhof, N

2001-08-01

Coronary arterial inflow is impeded and venous outflow is increased as a result of the decrease in coronary vascular volume due to cardiac contraction. We evaluated whether cardiac contraction is influenced by interfering with the changes of the coronary vascular volume over the heart cycle. Length-tension relationships were determined in Tyrode-perfused rat papillary muscle and when coronary vascular volume changes were partly inhibited by filling it with congealed gelatin or perfusing it with a high viscosity dextran buffer. Also, myocyte thickening during contraction was reduced by placing a silicon tube around the muscle. Increasing perfusion pressure from 8 to 80 cmH2O, increased developed tension by approximately 40%. When compared with the low perfusion state, developed tension of the gelatin-filled vasculature was reduced to 43 +/- 6% at the muscle length where the muscle generates the largest developed tension (n = 5, means +/- SE). Dextran reduced developed tension to 73 +/- 6% (n = 6). The silicon tube, in low perfusion state, reduced the developed tension to 83 +/- 7% (n = 4) of control. Time-control and oxygen-lowering experiments show that the findings are based on mechanical effects. Thus interventions to prevent myocyte thickening reduce developed tension. We hypothesize that when myocyte thickening is prevented, intracellular pressure increases and counteracts the force produced by the contractile apparatus. We conclude that emptying of the coronary vasculature serves a physiological purpose by facilitating cardiomyocyte thickening thereby augmenting force development.

3D curvature of muscle fascicles in triceps surae

PubMed Central

Hamarneh, Ghassan; Wakeling, James M.

2014-01-01

Muscle fascicles curve along their length, with the curvatures occurring around regions of high intramuscular pressure, and are necessary for mechanical stability. Fascicles are typically considered to lie in fascicle planes that are the planes visualized during dissection or two-dimensional (2D) ultrasound scans. However, it has previously been predicted that fascicles must curve in three-dimensional (3D) and thus the fascicle planes may actually exist as 3D sheets. 3D fascicle curvatures have not been explored in human musculature. Furthermore, if the fascicles do not lie in 2D planes, then this has implications for architectural measures that are derived from 2D ultrasound scans. The purpose of this study was to quantify the 3D curvatures of the muscle fascicles and fascicle sheets within the triceps surae muscles and to test whether these curvatures varied among different contraction levels, muscle length, and regions within the muscle. Six male subjects were tested for three torque levels (0, 30, and 60% maximal voluntary contraction) and four ankle angles (−15, 0, 15, and 30° plantar flexion), and fascicles were imaged using 3D ultrasound techniques. The fascicle curvatures significantly increased at higher ankle torques and shorter muscle lengths. The fascicle sheet curvatures were of similar magnitude to the fascicle curvatures but did not vary between contractions. Fascicle curvatures were regionalized within each muscle with the curvature facing the deeper aponeuroses, and this indicates a greater intramuscular pressure in the deeper layers of muscles. Muscle architectural measures may be in error when using 2D images for complex geometries such as the soleus. PMID:25324510

MSH3 Promotes Dynamic Behavior of Trinucleotide Repeat Tracts In Vivo.

PubMed

Williams, Gregory M; Surtees, Jennifer A

2015-07-01

Trinucleotide repeat (TNR) expansions are the underlying cause of more than 40 neurodegenerative and neuromuscular diseases, including myotonic dystrophy and Huntington's disease, yet the pathway to expansion remains poorly understood. An important step in expansion is the shift from a stable TNR sequence to an unstable, expanding tract, which is thought to occur once a TNR attains a threshold length. Modeling of human data has indicated that TNR tracts are increasingly likely to expand as they increase in size and to do so in increments that are smaller than the repeat itself, but this has not been tested experimentally. Genetic work has implicated the mismatch repair factor MSH3 in promoting expansions. Using Saccharomyces cerevisiae as a model for CAG and CTG tract dynamics, we examined individual threshold-length TNR tracts in vivo over time in MSH3 and msh3Δ backgrounds. We demonstrate, for the first time, that these TNR tracts are highly dynamic. Furthermore, we establish that once such a tract has expanded by even a few repeat units, it is significantly more likely to expand again. Finally, we show that threshold- length TNR sequences readily accumulate net incremental expansions over time through a series of small expansion and contraction events. Importantly, the tracts were substantially stabilized in the msh3Δ background, with a bias toward contractions, indicating that Msh2-Msh3 plays an important role in shifting the expansion-contraction equilibrium toward expansion in the early stages of TNR tract expansion. Copyright © 2015 by the Genetics Society of America.

The effect of pneumatic dilation in management of postfundoplication dysphagia.

PubMed

Sunjaya, D; Podboy, A; Blackmon, S H; Katzka, D; Halland, M

2017-06-01

Fundoplication surgery is a commonly performed procedure for gastro-esophageal reflux disease or hiatal hernia repair. Up to 10% of patients develop persistent postoperative dysphagia after surgery. Data on the effectiveness of pneumatic dilation for treatment are limited. The aim of this study was to evaluate clinical outcomes and identify clinical factors associated with successful response to pneumatic dilation among patients with persistent postfundoplication dysphagia (PPFD). We retrospectively evaluated patients who had undergone pneumatic dilation for PPFD between 1999 and 2016. Patients with dysphagia or achalasia prior to fundoplication were excluded. Demographic information, surgical history, severity of dysphagia, and clinical outcomes were collected. Data pertaining to esophagram, manometry, endoscopy, and pneumatic dilation were also collected. We identified 38 patients (82% female, 95% Caucasian, and median age 59 years) with PPFD who completed pneumatic dilation. The median postfundoplication dysphagia score was 2. Eleven patients had abnormal peristalsis on manometry. Seventeen patients reported response (seven complete) with an average decrease of 1 in their dysphagia score. Fifteen patients underwent reoperation due to PPFD. Hiatal hernia repair was the only factor that predicts a higher response rate to pneumatic dilation. Only one patient in our study developed complication (pneumoperitoneum) from pneumatic dilation. We found that pneumatic dilation to be a safe treatment option for PPFD with moderate efficacy. Patients who developed PPFD after a hiatal hernia repair may gain the greatest benefit after pneumatic dilation. We were not able to identify additional clinical, radiological, endoscopic, or manometric parameters that were predictive of response. © 2017 John Wiley & Sons Ltd.

A comparison of two methods of endoscopic dilation of acute subglottic stenosis using a ferret model.

PubMed

Tubbs, Kyle J; Silva, Rodrigo C; Ramirez, Harvey E; Castleman, William L; Collins, William O

2013-01-01

Balloon dilation is accepted as a first line treatment of acute subglottic stenosis, but its effects on the subglottic tissue remain largely unknown. We aimed to develop an animal model of acute subglottic stenosis using endoscopic techniques. Once developed, this model was used to compare the immediate effects of balloon dilation and endotracheal tube dilation on subglottic tissue. Prospective randomized animal study. Acute subglottic injury was induced in 10 ferrets by endoscopic cauterization with silver nitrate. After 48-72 hours of observation, eight animals were randomized to undergo subglottic dilation with either a 5-mm balloon or endotracheal tubes of increasing diameter. These eight ferrets were euthanized within 10 minutes after dilation. The other two ferrets served as controls and were euthanized following observation only. The larynx from each ferret was harvested, and the subglottis was examined histologically by a pathologist blinded to the treatment arms. Acute subglottic stenosis was induced in all 10 ferrets using the endoscopic technique. Both balloon and endotracheal tube dilation resulted in comparable improvement in the subglottic airway diameter. A decreased thickness of submucosa/lamina propria was seen in the balloon dilation group. Acute subglottic stenosis can be reliably induced in ferrets using endoscopic techniques. Multiple dilation methods can be used to relieve acute obstruction. Balloon dilators seem to improve airway patency, in part, by decreasing the thickness of the submucosa and lamina propria. Further research is needed to determine how this impacts later stages of wound healing and final outcomes. Copyright © 2012 The American Laryngological, Rhinological, and Otological Society, Inc.

Endoscopic dilation for treatment of anastomotic leaks following transhiatal esophagectomy.

PubMed

Bhasin, D K; Sharma, B C; Gupta, N M; Sinha, S K; Singh, K

2000-06-01

Anastomotic leak is a known complication after transhiatal esophagectomy (THE) and cervical esophagogastric anastomosis. Conservative management takes a long time to heal such leaks. We assessed the role of endoscopic dilation in patients with anastomotic leak following THE. Eight consecutive patients (seven men, one woman; mean age 51) with anastomotic leak following THE were subjected to endoscopic dilation using Savary Gilliard dilators of 7-15 mm diameter. The mean interval between surgery and detection of leak was 9 days (range 5-22 days) and dilation was performed at a mean interval of 11.4 days (range 1-20 days) after detection of the leak. Drainage from fistulas stopped completely after 1-8 days (mean 3 days). X-ray with water soluble contrast showed closure of the fistula in all cases. Duration of follow-up ranged from 2 to 12 months. Anastomotic strictures developed in three patients. These patients required three sessions each of repeat dilation, and were alive at follow-up periods of 2, 4, and 12 months, respectively. One patient developed recurrence of growth at an anastomotic site. Four patients died because of distant metastasis. Bougie dilation of anastomotic sites is a safe and effective technique for the healing of anastomotic leaks following THE. However there is a need for a prospective randomized trial comparing endoscopic dilation with no dilation in patients with anastomotic leaks following THE.

Pupil dilation signals uncertainty and surprise in a learning gambling task.

PubMed

Lavín, Claudio; San Martín, René; Rosales Jubal, Eduardo

2013-01-01

Pupil dilation under constant illumination is a physiological marker where modulation is related to several cognitive functions involved in daily decision making. There is evidence for a role of pupil dilation change during decision-making tasks associated with uncertainty, reward-prediction errors and surprise. However, while some work suggests that pupil dilation is mainly modulated by reward predictions, others point out that this marker is related to uncertainty signaling and surprise. Supporting the latter hypothesis, the neural substrate of this marker is related to noradrenaline (NA) activity which has been also related to uncertainty signaling. In this work we aimed to test whether pupil dilation is a marker for uncertainty and surprise in a learning task. We recorded pupil dilation responses in 10 participants performing the Iowa Gambling Task (IGT), a decision-making task that requires learning and constant monitoring of outcomes' feedback, which are important variables within the traditional study of human decision making. Results showed that pupil dilation changes were modulated by learned uncertainty and surprise regardless of feedback magnitudes. Interestingly, greater pupil dilation changes were found during positive feedback (PF) presentation when there was lower uncertainty about a future negative feedback (NF); and by surprise during NF presentation. These results support the hypothesis that pupil dilation is a marker of learned uncertainty, and may be used as a marker of NA activity facing unfamiliar situations in humans.

Pupil dilation signals uncertainty and surprise in a learning gambling task

PubMed Central

Lavín, Claudio; San Martín, René; Rosales Jubal, Eduardo

2014-01-01

Pupil dilation under constant illumination is a physiological marker where modulation is related to several cognitive functions involved in daily decision making. There is evidence for a role of pupil dilation change during decision-making tasks associated with uncertainty, reward-prediction errors and surprise. However, while some work suggests that pupil dilation is mainly modulated by reward predictions, others point out that this marker is related to uncertainty signaling and surprise. Supporting the latter hypothesis, the neural substrate of this marker is related to noradrenaline (NA) activity which has been also related to uncertainty signaling. In this work we aimed to test whether pupil dilation is a marker for uncertainty and surprise in a learning task. We recorded pupil dilation responses in 10 participants performing the Iowa Gambling Task (IGT), a decision-making task that requires learning and constant monitoring of outcomes’ feedback, which are important variables within the traditional study of human decision making. Results showed that pupil dilation changes were modulated by learned uncertainty and surprise regardless of feedback magnitudes. Interestingly, greater pupil dilation changes were found during positive feedback (PF) presentation when there was lower uncertainty about a future negative feedback (NF); and by surprise during NF presentation. These results support the hypothesis that pupil dilation is a marker of learned uncertainty, and may be used as a marker of NA activity facing unfamiliar situations in humans. PMID:24427126

Cervical dilation before first-trimester surgical abortion (<14 weeks' gestation).

PubMed

Allen, Rebecca H; Goldberg, Alisa B

2016-04-01

First-trimester surgical abortion is a common, safe procedure with a major complication rate of less than 1%. Cervical dilation before suction abortion is usually accomplished using tapered mechanical dilators. Risk factors for major complications in the first trimester include increasing gestational age and provider inexperience. Cervical priming before first-trimester surgical abortion has been studied using osmotic dilators and pharmacologic agents, most commonly misoprostol. Extensive data demonstrate that a variety of agents are safe and effective at causing preoperative cervical softening and dilation; however, given the small absolute risk of complications, the benefit of routine use of misoprostol or osmotic dilators in first-trimester surgical abortion is unclear. Although cervical priming results in reduced abortion time and improved provider ease, it requires a delay of at least 1 to 3 h and may confer side effects. The Society of Family Planning does not recommend routine cervical priming for first-trimester suction abortion but recommends limiting consideration of cervical priming for women at increased risk of complications from cervical dilation, including those late in the first trimester, adolescents and women in whom cervical dilation is expected to be challenging. Copyright © 2016 Elsevier Inc. All rights reserved.

Balloon dilatation of nasopharyngeal stenosis in a dog.

PubMed

Berent, Allyson C; Kinns, Jennifer; Weisse, Chick

2006-08-01

A dog was examined because of a 6-month history of upper airway stridor that began after postoperative regurgitation of gastric contents. Constant stridor was evident during inspiration and expiration, although it was worse during inspiration. The stridor was no longer evident when the dog's mouth was manually held open. Computed tomography, rhinoscopy, and fluoroscopy were used to confirm a diagnosis of nasopharyngeal stenosis. The dog was anesthetized, and balloon dilatation of the stenosis was performed. Prednisone was prescribed for 4 weeks after the procedure to decrease fibrous tissue formation. Although the dog was initially improved, signs recurred 3.5 weeks later, and balloon dilatation was repeated. This time, however, triamcinolone was injected into the area of stenosis at the end of the dilatation procedure. Two months later, although the dog did not have clinical signs of stridor, a third dilatation procedure was performed because mild stenosis was seen on follow-up computed tomographic images; again, triamcinolone was injected into the area of stenosis at the end of the dilatation procedure. Three and 6 months after the third dilatation procedure, the dog reportedly was clinically normal. Findings suggest that balloon dilatation may be an effective treatment for nasopharyngeal stenosis in dogs.

Treatments for pediatric achalasia: Heller myotomy or pneumatic dilatation?

PubMed

Jung, C; Michaud, L; Mougenot, J-F; Lamblin, M-D; Philippe-Chomette, P; Cargill, G; Bonnevalle, M; Boige, N; Bellaïche, M; Viala, J; Hugot, J-P; Gottrand, F; Cezard, J-P

2010-03-01

The treatment of achalasia consists of reducing distal esophageal obstruction by either Heller myotomy surgery or endoscopic pneumatic dilatation. The aim of the present study was to evaluate the short- and middle-term results of these procedures in children. For technical reasons, children under six years old (n=8) were treated by surgery only, whereas patients over six years old (n=14) were treated by either Heller myotomy or pneumatic dilatation. Of the children aged under six years, 75% were symptom-free at six months and 83% at 24 months of follow-up. Of the patients aged over six years, complete remission was achieved by Heller myotomy in 44.5% vs. 55.5% by pneumatic dilatation after six months, and in 40% vs. 65%, respectively, after 24 months. Both pneumatic dilatation and Heller myotomy showed significant rates of failure. These results suggest that pneumatic dilatation may be considered a primary treatment in children over six years old. Also, where necessary, Heller myotomy and pneumatic dilatation may be used as complementary treatments.

Crack Damage Parameters and Dilatancy of Artificially Jointed Granite Samples Under Triaxial Compression

NASA Astrophysics Data System (ADS)

Walton, G.; Alejano, L. R.; Arzua, J.; Markley, T.

2018-06-01

A database of post-peak triaxial test results was created for artificially jointed planes introduced in cylindrical compression samples of a Blanco Mera granite. Aside from examining the artificial jointing effect on major rock and rock mass parameters such as stiffness, peak strength and residual strength, other strength parameters related to brittle cracking and post-yield dilatancy were analyzed. Crack initiation and crack damage values for both the intact and artificially jointed samples were determined, and these damage envelopes were found to be notably impacted by the presence of jointing. The data suggest that with increased density of jointing, the samples transition from a combined matrix damage and joint slip yielding mechanism to yield dominated by joint slip. Additionally, post-yield dilation data were analyzed in the context of a mobilized dilation angle model, and the peak dilation angle was found to decrease significantly when there were joints in the samples. These dilatancy results are consistent with hypotheses in the literature on rock mass dilatancy.

Pupil dilation during recognition memory: Isolating unexpected recognition from judgment uncertainty.

PubMed

Mill, Ravi D; O'Connor, Akira R; Dobbins, Ian G

2016-09-01

Optimally discriminating familiar from novel stimuli demands a decision-making process informed by prior expectations. Here we demonstrate that pupillary dilation (PD) responses during recognition memory decisions are modulated by expectations, and more specifically, that pupil dilation increases for unexpected compared to expected recognition. Furthermore, multi-level modeling demonstrated that the time course of the dilation during each individual trial contains separable early and late dilation components, with the early amplitude capturing unexpected recognition, and the later trailing slope reflecting general judgment uncertainty or effort. This is the first demonstration that the early dilation response during recognition is dependent upon observer expectations and that separate recognition expectation and judgment uncertainty components are present in the dilation time course of every trial. The findings provide novel insights into adaptive memory-linked orienting mechanisms as well as the general cognitive underpinnings of the pupillary index of autonomic nervous system activity. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of Citrus Aurantium (Bitter Orange) on the Severity of First-Stage Labor Pain

PubMed Central

Namazi, Masoumeh; Amir Ali Akbari, Seddigheh; Mojab, Faraz; Talebi, Atefe; Alavi Majd, Hamid; Jannesari, Sharareh

2014-01-01

Considering that vaginal delivery is a painful process, the present study investigated the effects of Citrus aurantium on the severity of first-stage labor pain in primiparous women. This study was a randomized clinical trial conducted with 126 eligible primiparous patients. The pain severity of patients was measured at the time of enrolling in the study. In the intervention group, (aromatherapy) gauze squares were soaked in 4 ml of C. aurantium distillated water, and in the control group, gauze squares were soaked in 4 ml of normal saline; each gauze square was attached to the respective patients’ collar. The intervention was repeated every 30 min. Pain severity was measured after the intervention at 3–4, 5–7, and 8–10 cm cervix dilatations. The two groups were standardized with regard to age, profession, education, desire to conceive, and number and severity of uterine contractions. The Bishop’s score was also calculated. Before intervention, pain severity was the same for both groups, but following intervention, pain severity reduced in the intervention group at 3–4 centimeter (P < 0.05), 7–5 centimeter (P < 0.05), and 8–10 centimeter (P < 0.05) dilatations compared with that in the control group. The findings of the study revealed that aromatherapy using C. aurantium distillated water alleviates labor pain. This method is recommended because of its ease of use and low cost and because it is a non-aggressive method to reduce labor pain. PMID:25276203

Our ultrasonographic experience in the management of symptomatic hydronephrosis during pregnancy.

PubMed

Dell'Atti, Lucio

2016-03-01

The aim of the present study was to document the role of ultrasound in the diagnosis and management of symptomatic hydronephrosis during pregnancy. In this study, we reviewed 36 consecutive cases of pregnant women whose pregnancy was complicated by symptomatic hydronephrosis. In all patients, management was initially conservative (analgesics and fluids) after hospitalization. The following criteria were used to indicate double-J stent placement under US guidance rather than a conservative treatment: persistent pain with no improvement after conservative treatment, progressive hydronephrosis (>2 cm dilatation of the renal pelvis) or presence of uterine contractions. The mean patient's age was 25 years (17-35) and gestational age at clinical presentation was 24 weeks (13-37). 81 % of cases had a renal pelvis dilatation >2 cm, while in only 19 % of cases there was a hydronephrosis between 1 and 2 cm in diameter; however, calculi were confirmed only in 25 patients. 28 patients required an invasive management with double-J stent insertion under US guidance. The sensitivity and specificity of US in the etiological diagnosis of hydronephrosis during pregnancy was 83 and 91 %, respectively. Conservative management with medical therapy and observation should be the first-line treatment approach. In our opinion a rapid ureteral decompression with the insertion of a ureteral double-J stent, under US visualization, is the safest method in the treatment of pregnant women with obstructed renal systems.

Identification of the Muscarinic Acetylcholine Receptor Subtype Mediating Cholinergic Vasodilation in Murine Retinal Arterioles

PubMed Central

Sniatecki, Jan J.; Goloborodko, Evgeny; Steege, Andreas; Zavaritskaya, Olga; Vetter, Jan M.; Grus, Franz H.; Patzak, Andreas; Wess, Jürgen; Pfeiffer, Norbert

2011-01-01

Purpose. To identify the muscarinic acetylcholine receptor subtype that mediates cholinergic vasodilation in murine retinal arterioles. Methods. Muscarinic receptor gene expression was determined in murine retinal arterioles using real-time PCR. To assess the functional relevance of muscarinic receptors for mediating vascular responses, retinal vascular preparations from muscarinic receptor–deficient mice were studied in vitro. Changes in luminal arteriole diameter in response to muscarinic and nonmuscarinic vasoactive substances were measured by video microscopy. Results. Only mRNA for the M3 receptor was detected in retinal arterioles. Thus, M3 receptor–deficient mice (M3R−/−) and respective wild-type controls were used for functional studies. Acetylcholine concentration-dependently dilated retinal arterioles from wild-type mice. In contrast, vasodilation to acetylcholine was almost completely abolished in retinal arterioles from M3R−/− mice, whereas responses to the nitric oxide (NO) donor nitroprusside were retained. Carbachol, an acetylcholinesterase-resistant analog of acetylcholine, also evoked dilation in retinal arterioles from wild-type, but not from M3R−/−, mice. Vasodilation responses from wild-type mice to acetylcholine were negligible after incubation with the non–subtype-selective muscarinic receptor blocker atropine or the NO synthase inhibitor Nω-nitro-l-arginine methyl ester, and were even reversed to contraction after endothelial damage with 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate. Conclusions. These findings provide evidence that endothelial M3 receptors mediate cholinergic vasodilation in murine retinal arterioles via activation of NO synthase. PMID:21873683

Impact of Acid Attack on the Shear Behaviour of a Carbonate Rock Joint

NASA Astrophysics Data System (ADS)

Nouailletas, O.; Perlot, C.; Rivard, P.; Ballivy, G.; La Borderie, C.

2017-06-01

The mechanical behaviour of structural discontinuities in rock mass is a key element of the stability analysis in civil engineering, petroleum engineering and mining engineering. In this paper, the mechanical analysis is coupled with the acidic attack of a rock joint associated with leakage of CO2 through a geological fault in the context of carbon sequestration. Experiments were conducted at the laboratory scale to assess the shear behaviour of degraded joint: direct shear tests were performed on rock joints that have been previously immersed into water or into an acidic solution (pH 0.2). The shear behaviour of joints is governed by the roughness of its walls: the parameters Z2, Z3, Z4 and RL characterize the rough surfaces. They are calculated from the scans of joint surfaces after and before immersion. Their comparison pointed out a slight impact of the acidic attack. However, the results of the direct shear tests show significant modifications in the shear behaviour for the degraded joints: the tangential stress peak disappears, the tangential stiffness decreases in the stress/displacement curve, and the contraction increases, the dilation angle decreases in the dilation curve. Acid attack has a greater impact on the mechanical properties of the asperities than their geometric characteristics. The results of this study will be used to improve chemo-mechanical modelling to better simulate with higher accuracy the fault stability in different cases of civil engineering, petroleum engineering and mining engineering.

Prevalence of dilated cardiomyopathy in Doberman Pinschers in various age groups.

PubMed

Wess, G; Schulze, A; Butz, V; Simak, J; Killich, M; Keller, L J M; Maeurer, J; Hartmann, K

2010-01-01

Dilated cardiomyopathy (DCM) in Doberman Pinschers is an autosomal dominant inherited disease. The prevalence of DCM in Doberman Pinschers of various age groups in Europe is currently unknown, but this information would be important to develop recommendations for screening programs. To evaluate the prevalence of cardiomyopathy in various age groups of Dobermans. Seven hundred and seventy-five examinations in 412 Doberman Pinschers. Dogs were included in a prospective longitudinal cohort study. Each examination included echocardiography and 24-hour ECG (Holter) examination. A cut-off value of >100 ventricular premature contractions (VPCs) per 24 hours on Holter examination or abnormal echocardiography was considered diagnostic for cardiomyopathy. The cumulative prevalence included all dogs with DCM and healthy dogs >7 years of age. DCM prevalence in various age groups was as follows: age group 1 (1 to <2 years) 3.3%, age group 2 (2 to <4 years) 9.9%, age group 3 (4 to <6 years) 12.5%, age group 4 (6 to <8 years) 43.6%, and age group 5 (>8 years) 44.1%. The cumulative prevalence of Doberman Pinscher cardiomyopathy was 58.2%. There was an equal sex distribution, but male dogs showed earlier echocardiographic changes than did female dogs, which had significantly more VPCs. The prevalence of Doberman cardiomyopathy is very high in Europe. Disease manifestation and progression are different between male and female dogs. Yearly screening for DCM by Holter examination and echocardiography is recommended, starting at 2 years of age.

Spectral dilation of L(B,H)-valued measures and its application to stationary dilation for Banach space valued processes

NASA Technical Reports Server (NTRS)

Miamee, A. G.

1988-01-01

Let B be a Banach space and H and K two Hilbert spaces. The spectral dilation of L(B,H)-valued measures is studied and it is shown that the recent results of Makagon and Salehi (1986) and Rosenberg (1982) on the dilation of L(K,H)-valued measures can be extended to hold for the general Banach space setting of L(B,H)-valued measures. These L(B,H)-valued measures are closely connected to the Banach space valued processes. This connection is recalled and as application of spectral dilation of L(B,H)-valued measures the well known stationary dilation results for scalar valued processes is extended to the case of Banach space valued processes.