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Shortening
Kinds of Shortening Terms modified by Shortening Selected AbstractsThe Nested M-Plasty for Scar Length ShorteningDERMATOLOGIC SURGERY, Issue 9 2008RAVI S. KRISHNAN MD No abstract is available for this article. [source] Effects of Alcohol Septal Ablation for Hypertrophic Obstructive Cardiomyopathy on Doppler Tei Index: A Midterm Follow-UpECHOCARDIOGRAPHY, Issue 2 2005F.E.S.C., Josef Veselka M.D., Ph.D. Alcohol septal ablation (PTSMA) improves outflow gradient, left ventricular (LV) diastolic function, and symptoms in patients with hypertrophic obstructive cardiomyopathy (HOCM). Tei index (TI) is a Doppler parameter reflecting both systolic and diastolic LV function. Midterm changes of TI after PTSMA have not been determined up to now. Twenty-seven consecutive patients (mean age 53 ± 13 years) with symptomatic HOCM underwent PTSMA procedure. Clinical and echocardiographic data were collected at baseline, 6 and 12 months after PTSMA. TI decreased from 0.67 ± 0.11 to 0.55 ± 0.06, isovolumic contractile time (ICT) decreased from 74 ± 20 to 48 ± 11 ms, isovolumic relaxation time decreased from 146 ± 25 to 117 ± 9 ms, and LV ejection time decreased from 330 ± 42 to 298 ± 13 ms. LV remodeling was determined by LV dimension increase from 46 ± 6 to 48 ± 6 mm and basal septum thickness reduction from 22 ± 4 to 15 ± 3 mm. LV ejection fraction decreased from 78 ± 7 to 73 ± 6% and maximal outflow gradient decreased from 69 ± 44 to 15 ± 11 mmHg. All changes were statistically significant (P < 0.01). Symptomatic improvement was characterized by relief of dyspnea (2.5 ± 0.7 versus 1.4 ± 0.6 NYHA class; P < 0.01) and angina pectoris (2.6 ± 0.9 versus 0.7 ± 0.7 CCS class; P < 0.01). PTSMA is an effective method of therapy for HOCM. Shortening of TI suggests the improvement of LV myocardial performance in the midterm follow-up. [source] Estimation of Global Left Ventricular Function from the Velocity of Longitudinal ShorteningECHOCARDIOGRAPHY, Issue 3 2002Dragos Vinereanu M.D., E.C., Ph.D. Aims: To determine if global ventricular function can be assessed from the long-axis contraction of the left ventricle, we compared pulsed-wave Doppler myocardial imaging of mitral annular motion to radionuclide ventriculography. Methods and Results: We studied 51 patients (56 ± 10 years, 11 women) with a radionuclide ejection fraction of 52 ± 13% (15%,70%). Peak systolic velocities of medial and lateral mitral annular motion correlated with ejection fraction (0.55 and 0.54, respectively; P < 0.001), as did the time-velocity integrals (0.57 and 0.58, respectively; P < 0.001). Correlations were higher in normal ventricles (0.62,0.69) than in patients with previous myocardial infarction (0.39,0.64). Patients with anterior myocardial infarction had the lowest correlations (0.39,0.46). The best differentiation of normal (, 50%) from abnormal (< 50%) ejection fraction was provided by peak systolic velocity , 8 cm/sec for the medial (sensitivity 80%, specificity 89%) or lateral (sensitivity 80%, specificity 92%) mitral annulus. Conclusion: Global left ventricular function can be estimated by recording mitral annular velocity. The implementation of a cutoff limit of 8 cm/sec gave a simple guide for differentiating between normal and abnormal left ventricular systolic function that might be useful clinically in patients without regional wall-motion abnormalities. However, in patients with important segmental wall-motion abnormalities during systole, left ventricular longitudinal shortening is an imperfect surrogate for ejection fraction. [source] Chronic effects of type 2 diabetes mellitus on cardiac muscle contraction in the Goto-Kakizaki ratEXPERIMENTAL PHYSIOLOGY, Issue 6 2007F. C. Howarth Type 2 diabetes mellitus accounts for more than 90% of all cases of diabetes mellitus, and cardiovascular complications are the major cause of mortality and death in diabetic patients. The chronic effects of type 2 diabetes mellitus on heart function have been investigated in the Goto-Kakizaki (GK) rat. Experiments were performed in GK rats and age-matched Wistar control rats at 18 months of age. The progressive effects of diabetes on glucose metabolism were monitored periodically by application of the glucose tolerance test. Ventricular action potentials were measured in isolated, perfused heart. Shortening and intracellular Ca2+ were measured in electrically stimulated ventricular myocytes. The GK rats displayed mild fasting hyperglycaemia and progressively worsening glucose tolerance. At 18 months of age and 180 min after intraperitoneal injection of glucose (2 g (kg body weight),1), blood glucose was 436 ± 47 mg dl,1 in GK rats compared with 153 ± 18 mg dl,1 in control animals. Heart weight to body weight ratio was significantly increased in GK rats (4.10 ± 0.09 mg g,1, n= 5) compared with control animals (3.36 ± 0.22 mg g,1, n= 4). Spontaneous heart rate was slightly reduced in GK rats compared with control rats. Although the amplitude of shortening was not altered, the amplitude of the Ca2+ transient was significantly increased in myocytes from GK rats (0.78 ± 0.11 ratio units) compared with control rats (0.50 ± 0.06 ratio units). Despite progressively worsening glucose metabolism, at 18 months of age the contractile function of the heart appears to be well preserved. [source] Region-specific assessment of greenhouse gas mitigation with different manure management strategies in four agroecological zonesGLOBAL CHANGE BIOLOGY, Issue 12 2009SVEN G. SOMMER Abstract Livestock farming systems are major sources of trace gases contributing to emissions of the greenhouse gases (GHG) nitrous oxide (N2O) and methane (CH4), i.e. N2O accounts for 10% and CH4 for 30% of the anthropogenic contributions to net global warming. This paper presents scenario assessments of whole-system effects of technologies for reducing GHG emissions from livestock model farms using slurry-based manure management. Changes in housing and storage practice, mechanical separation, and incineration of the solid fraction derived from separation were evaluated in scenarios for Sweden, Denmark, France, and Italy. The results demonstrated that changes in manure management can induce significant changes in CH4 and N2O emissions and carbon sequestration, and that the effect of introducing environmental technologies may vary significantly with livestock farming practice and interact with climatic conditions. Shortening the in-house manure storage time reduced GHG emissions by 0,40%. The largest GHG reductions of 49 to, in one case, 82% were obtained with a combination of slurry separation and incineration, the latter process contributing to a positive GHG balance of the system by substituting fossil fuels. The amount and composition of volatile solids (VS) and nitrogen pools were main drivers in the calculations performed, and requirements to improve the assessment of VS composition and turnover during storage and in the field were identified. Nevertheless, the results clearly showed that GHG emission estimates will be unrealistic, if the assumed manure management or climatic conditions do not properly represent a given country or region. The results also showed that the mitigation potential of specific manure management strategies and technologies varied depending on current management and climatic conditions. [source] Inhibitors of the Na+/H+ Exchanger Cannot Prevent Atrial Electrical Remodeling in the GoatJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 4 2004YURI BLAAUW M.D. Introduction: It has been suggested that blockade of the Na+/H+ exchanger (NHE1) can prevent atrial fibrillation (AF)-induced electrical remodeling and the development of AF. Methods and Results: AF was maintained by burst pacing in 10 chronically instrumented conscious goats. Intravenous and oral dosages of two NHE1 blockers (EMD87580 and EMD125021) resulted in plasma levels several magnitudes higher than required for effective NHE1 blockade. Shortening of atrial refractoriness immediately after 5 minutes of AF was not prevented by NHE1 blockade. In remodeled atria, increasing dosages of EMD87580 and EMD125021 did not reverse shortening of the atrial refractory period or reduce the duration of AF episodes. The cycle length during persistent AF also was not affected. Oral pretreatment with EMD87580 (8 mg/kg bid) starting 3 days before AF could not prevent electrical remodeling. After 24 and 48 hours of remodeling, the duration of AF paroxysms was 47 ± 32 seconds and 135 ± 63 seconds compared to 56 ± 17 seconds and 136 ± 52 seconds in placebo-treated animals (P > 0.8), respectively. Conclusion: In the goat model of AF, the Na+/H+ exchanger inhibitors EMD87580 and EMD125021 did not prevent or revert AF-induced electrical remodeling. This indicates that activation of the Na+/H+ exchanger is not involved in the intracellular pathways of electrical remodeling. This does not support the suggestion that blockers of the Na+/H+ exchanger may be beneficial for prevention and treatment of AF. (J Cardiovasc Electrophysiol, Vol. 15, pp. 440-446, April 2004) [source] Relationship Between Regional Shortening and Asynchronous Electrical Activation in a Three-Dimensional Model of Ventricular ElectromechanicsJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 2003TARAS P. USYK Ph.D. Introduction: Asynchronous electrical activation can cause abnormalities in perfusion and pump function. An electromechanical model was used to investigate the mechanical effects of altered cardiac activation sequence. Methods and Results: We used an anatomically detailed three-dimensional computational model of the canine ventricular walls to investigate the relationship between regional electrical activation and the timing of fiber shortening during normal and ventricular paced beats. By including a simplified Purkinje fiber network and anisotropic impulse conduction in the model, computed electrical activation sequences were consistent with experimentally observed patterns. Asynchronous time courses of regional strains during beats stimulated from the left or right ventricular epicardium showed good agreement with published experimental measurements in dogs using magnetic resonance imaging tagging methods. When electrical depolarization in the model was coupled to the onset of local contractile tension development by a constant time delay of 8 msec, the mean delay from depolarization to the onset of systolic fiber shortening was 14 msec. However, the delay between the onset of fiber tension and initial shortening varied significantly; it was as late as 60 msec in some regions but was also as early as ,50 msec (i.e., 42 msec before depolarization) in other regions, particularly the interventricular septum during free-wall pacing. Conclusion: The large variation in delay times was attributable to several factors including local anatomic variations, the location of the site relative to the activation wavefront, and regional end-diastolic strain. Therefore, we conclude that these factors, which are intrinsic to three-dimensional ventricular function, make the regional sequence of fiber shortening an unreliable surrogate for regional depolarization or electromechanical activation in the intact ventricles. (J Cardiovasc Electrophysiol, Vol. 14, pp. S196-S202, October 2003, Suppl.) [source] PALM OIL SHORTENING EFFECTS ON BAKING PERFORMANCE OF WHITE BREADJOURNAL OF FOOD PROCESS ENGINEERING, Issue 3 2010NYUK LING CHIN ABSTRACT The effect of the addition of palm oil shortening up to 10% on baking performance of white breads in terms of volume, oven spring, weight, density, color, crumb texture and shelf life using strong and weak flour was investigated. Shortening improved the volume and oven spring of bread at an optimum level of 4% for both strong and weak flour. The strong flour illustrated the effects of shortening more significantly than the weak flour as it produced loaves with higher volumes, oven spring and weight. Bread density decreased to its lowest at 4% of shortening before increasing but porosity decreased linearly with shortening level. These findings suggest that shortening has the optimum capability of reducing bread density at 4% and further addition resulted in dense and coarse bread. Addition of shortening also gave signs of whiter breads and mold reduction effect, although there is no particular trend with its usage levels. PRACTICAL APPLICATIONS This research presents the improvement in baking characteristics of white bread with addition of palm oil shortening at an optimum level of 4% for all three types of shortening with melting points ranging from 36,52C. The baking characteristics such as volume, oven spring, weight, density, color, crumb texture and shelf life were evaluated using newly developed research methods and also by adopting industrial practices. It was observed that addition of shortening gave signs of whiter breads and mold reduction effect. [source] Ultrasonic Investigation of the Effect of Vegetable Shortening and Mixing Time on the Mechanical Properties of Bread DoughJOURNAL OF FOOD SCIENCE, Issue 9 2009K.L. Mehta ABSTRACT:, Mixing is a critical stage in breadmaking since it controls gluten development and nucleation of gas bubbles in the dough. Bubbles affect the rheology of the dough and largely govern the quality of the final product. This study used ultrasound (at a frequency where it is sensitive to the presence of bubbles) to nondestructively examine dough properties as a function of mixing time in doughs prepared from strong red spring wheat flour with various amounts of shortening (0%, 2%, 4%, 8% flour weight basis). The doughs were mixed for various times at atmospheric pressure or under vacuum (to minimize bubble nucleation). Ultrasonic velocity and attenuation (nominally at 50 kHz) were measured in the dough, and dough density was measured independently from specific gravity determinations. Ultrasonic velocity decreased substantially as mixing time increased (and more bubbles were entrained) for all doughs mixed in air; for example, in doughs made without shortening, velocity decreased from 165 to 105 ms,1, although superimposed on this overall decrease was a peak in velocity at optimum mixing time. Changes in attenuation coefficient due to the addition of shortening were evident in both air-mixed and vacuum-mixed doughs, suggesting that ultrasound was sensitive to changes in the properties of the dough matrix during dough development and to plasticization of the gluten polymers by the shortening. Due to its ability to probe the effect of mixing times and ingredients on dough properties, ultrasound has the potential to be deployed as an online quality control tool in the baking industry. [source] Shortening of Median Door-to-Balloon Time in Primary Percutaneous Coronary Intervention in Singapore by Simple and Inexpensive Operational Measures: Clinical Practice Improvement ProgramJOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 5 2008CHI-HANG LEE M.B.B.S., F.A.C.C. Background: Primary percutaneous coronary intervention is the standard reperfusion strategy for ST-segment elevation myocardial infarction in our center. We aimed to shorten the median door-to-balloon time from over 100 minutes to 90 minutes or less. Methods: We have been using three strategies since March 2007 to shorten the door-to-balloon time: (1) the intervention team is now activated by emergency department physicians (where previously it had been activated by coronary care unit); (2) all members of the intervention team have converted from using pagers to using cell phones; and (3) as soon as the intervention team is activated, patients are transferred immediately to the cardiac catheterization laboratory (where previously they had waited in the emergency department for the intervention team to arrive). An in-house physician and a nurse would stay with the patients before arrival of the intervention team. Results: During 12 months, 285 nontransfer patients (analyzed, n = 270) underwent primary PCI. The shortest monthly median door-to-balloon time was 59 minutes; the longest monthly median door-to-balloon time was 111 minutes. The overall median door-to-balloon time for the entire 12 months was 72 minutes. On a per-month basis, the median door-to-balloon time was 90 minutes or less in 10 of 12 months. On a per-patient basis, the median door-to-balloon time was 90 minutes or less in 182 patients (67.4%). There was 1 case (0.4%) of inappropriate activation by the emergency department. While waiting for the intervention team to convene, 1 patient (0.4%) deteriorated and had to be resuscitated in the cardiac catheterization laboratory. Conclusions: Improved health care delivery can be achieved by changing simple and inexpensive operational processes. [source] Artifact-reduced two-dimensional cine steady state free precession for myocardial blood- oxygen-level-dependent imagingJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2010Xiangzhi Zhou PhD Abstract Purpose: To minimize image artifacts in long TR cardiac phase-resolved steady state free precession (SSFP) based blood-oxygen-level-dependent (BOLD) imaging. Materials and Methods: Nine healthy dogs (four male, five female, 20,25 kg) were studied in a clinical 1.5 Tesla MRI scanner to investigate the effect of temporal resolution, readout bandwidth, and motion compensation on long repetition time (TR) SSFP images. Breath-held 2D SSFP cine sequences with various temporal resolutions (10,204 ms), bandwidths (239,930 Hz/pixel), with and without first-order motion compensation were prescribed in the basal, mid-ventricular, and apical along the short axis. Preliminary myocardial BOLD studies in dogs with controllable coronary stenosis were performed to assess the benefits of artifact-reduction strategies. Results: Shortening the readout time by means of increasing readout bandwidth had no observable reduction in image artifacts. However, increasing the temporal resolution in the presence of first-order motion compensation led to significant reduction in image artifacts. Preliminary studies demonstrated that BOLD signal changes can be reliably detected throughout the cardiac cycle. Conclusion: Artifact-reduction methods used in this study provide significant improvement in image quality compared with conventional long TR SSFP BOLD MRI. It is envisioned that the methods proposed here may enable reliable detection of myocardial oxygenation changes throughout the cardiac cycle with long TR SSFP-based myocardial BOLD MRI. J. Magn. Reson. Imaging 2010;31:863,871. ©2010 Wiley-Liss, Inc. [source] Cost effectiveness of mass screening for coeliac disease is determined by time-delay to diagnosis and quality of life on a gluten-free dietALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 8 2010T. HERSHCOVICI Aliment Pharmacol Ther,31, 901,910 Summary Background, Coeliac disease is frequently diagnosed after a long delay resulting in increased morbidity and mortality. Aims, To define the parameters which have the highest impact on the cost-effectiveness of mass screening for coeliac disease. Methods, A Markov model examined a coeliac disease screening programme of the healthy young-adult general population compared with a no-screening strategy. The main outcome measures were quality adjusted life-years (QALYs) and incremental cost-effectiveness ratio (ICER). Effects of variables were examined using sensitivity analyses. Results, The screening strategy resulted in a gain of 0.0027 QALYs. The ICER of screening vs. no-screening strategy was US$48 960/QALYs. The variables with the largest impact on cost effectiveness were: the time delay from symptom onset to diagnosis, the utility of adherence to a gluten-free diet (GFD) and the prevalence of coeliac disease. Screening would be cost-effective if the time delay to diagnosis is longer than 6 years and utility of GFD adherence is greater than 0.978. Conclusions, Our model suggests that mass screening for coeliac disease of the young-adult general population is associated with improved QALYs and is a cost effectiveness strategy. Shortening of the time-delay to diagnosis by heightened awareness of health-care professionals may be a valid alternative to screening. [source] KATP channel openers: Structure-activity relationships and therapeutic potentialMEDICINAL RESEARCH REVIEWS, Issue 2 2004Raimund Mannhold Abstract ATP-sensitive potassium channels (KATP channels) are heteromeric complexes of pore-forming inwardly rectifying potassium channel subunits and regulatory sulfonylurea receptor subunits. KATP channels were identified in a variety of tissues including muscle cells, pancreatic ,-cells, and various neurons. They are regulated by the intracellular ATP/ADP ratio; ATP induces channel inhibition and MgADP induces channel opening. Functionally, KATP channels provide a means of linking the electrical activity of a cell to its metabolic state. Shortening of the cardiac action potential, smooth muscle relaxation, inhibition of both insulin secretion, and neurotransmitter release are mediated via KATP channels. Given their many physiological functions, KATP channels represent promising drug targets. Sulfonylureas like glibenclamide block KATP channels; they are used in the therapy of type 2 diabetes. Openers of KATP channels (KCOs), for example, relax smooth muscle and induce hypotension. KCOs are chemically heterogeneous and include as different classes as the benzopyrans, cyanoguanidines, thioformamides, thiadiazines, and pyridyl nitrates. Examples for new chemical entities more recently developed as KCOs include cyclobutenediones, dihydropyridine related structures, and tertiary carbinols. © 2003 Wiley Periodicals, Inc. Med Res Rev, 24, No. 2, 213,266, 2004 [source] Pulmonary Vein Morphology Before and After Segmental Isolation in Patients with Atrial FibrillationPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 9 2005MAREHIKO UEDA Background: The morphology of the pulmonary veins (PVs) before and after segmental isolation of the PVs has not been sufficiently characterized. Methods and Results: Multi-slice computed tomography was performed before and 3 ± 1 months after ablation in 30 patients with atrial fibrillation who underwent PV isolation. Before ablation, PV narrowing (,25% luminal reduction) was found in nine (8%) PVs. After ablation, de novo PV narrowing was found in 24 PVs (26%) and was detected only in the supero-inferior direction in 14 PVs (58%). The diameter reduction inside the PVs after ablation was greater in the supero-inferior direction (14 ± 12%) than in the antero-posterior direction (9 ± 13%; P < 0.0001). In the ablated PVs, the PV trunk was shorter than before ablation (P < 0.0001). The reduction in the diameters of both the PV ostium and the ablation site in the ablated PVs, as well as the diameter of the PV ostium in the nonablated PVs, correlated with the decrease in the left atrial diameter. Shortening of the PV trunk correlated with the severity of PV narrowing, but it was not related to the percent diameter reduction of the left atrium. PV narrowing before or after ablation did not result in any clinical consequences. Conclusions: PV narrowing is present in about 10% of PVs before ablation. Asymmetric luminal reduction and longitudinal shrinkage of the PV trunk occur after ablation. Reverse remodeling of the PV and contraction of the PV wall may contribute to the reduction in the PV diameter. PV morphology should be assessed with multi-directional views to avoid missing heterogeneous legions. [source] Electrocardiograms from the Turtle to the Elephant that Illustrate Interesting Physiological PhenomenaPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 12 2002L.A. GEDDES GEDDES, L.A. Electrocardiograms From the Turtle to the Elephant that Illustrate Interesting Physiological Phenomena. This article describes a collection of ECGs from many species obtained over the past 50 years. Presented are ECGs of species in which the pacemaker is a separate contractile chamber with its own action and recovery potentials. In such species, pacemaker atrial and AV block can be produced. Shortening of the atrial refractory period and the negative inotropic effect can be produced by vagal stimulation. The cardiac electrogram and stroke volume are recorded from the turtle heart. The ECG and respiration were recorded from the snake. ECG records were obtained from the anesthetized and decapitated housefly. ECG records of the rabbit show slowing when the nose encountered irritating vapors. Records from a dog with atrial fibrillation exhibit rhythmic fibrillation frequency changes correlated with respiration. In addition, in a morphinized dog with atrial fibrillation, impulses crossed the AV node only during inspiration. The ECGs of a cow and camel exhibit long P-R intervals and biphasic P waves. Finally the elephant ECG shows a clear U wave following the T wave. [source] Alpha-retinals as Rhodopsin Chromophores,Preference for the 9- Z Configuration and Partial Agonist Activity,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2008Yajie Wang The visual pigment rhodopsin, the photosensory element of the rod photoreceptor cell in the vertebrate retina, shows in combination with an endogenous ligand, 11- Z retinal, an astonishing photochemical performance. It exhibits an unprecedented quantum yield (0.67) in a highly defined and ultrafast photoisomerization process. This triggers the conformational changes leading to the active state Meta(rhodopsin) II. Retinal is covalently bound to Lys-296 of the protein opsin in a protonated Schiff base. The resulting positive charge delocalization over the terminal part of the polyene chain of retinal creates a conjugation defect that upon photoexcitation moves to the opposite end of the polyene. Shortening the polyene as in 4,5-dehydro,5,6-dihydro (alpha), 5,6-dihydro or 7,8-dihydro-analogs might facilitate photoisomerization of a 9- Z and a 11- Z bond. Here we describe pigment analogs generated with bovine opsin and 11- Z or 9- Z 4,5-dehydro,5,6-dihydro-retinal that were further characterized by UV,Vis and FTIR spectroscopy. The preference of opsin for native 11- Z retinal over the 9- Z isomer is reversed in 4,5-dehydro,5,6-dihydro-retinal. 9- Z 4,5-dehydro,5,6-dihydro-retinal readily generated a photosensitive pigment. This modification has no effect on the quantum yield, but affects the Batho,blueshifted intermediate (BSI) equilibrium and leads to a strong decrease in the G-protein activation rate because of a downshift of the pKa of the Meta I,Meta II equilibrium. [source] Dual-gate AlGaN/GaN high-electron-mobility transistors with short gate length for high-power mixersPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3 2006K. Shiojima Abstract We have fabricated dual-gate AlGaN/GaN high-electron-mobility transistors (HEMTs) with a short gate on SiC substrates for use in high-power mixers and have measured the DC and up-conversion RF characteristics. A device with a T-shaped gate (0.15 µm × 300 µm) exhibits a maximum transconductance of 40 mS, an on-state breakdown voltage of over 30 V, and off-state breakdown voltage of 86 V. The maximum RF output power (PRFout) is 17 dBm, and the up-conversion gain is 7.5 dB at a frequency of 10 GHz when the bias point voltage is 30 V. As the local frequency increases from 2 to 10 GHz, PRFout and the gain decrease by only 2 and 2.6 dB, respectively. Shortening the gate was found to be effective in improving the frequency characteristics of a mixer at frequencies up to and including the X-band. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Energetic consequences of being a Homo erectus femaleAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2002Leslie C. Aiello Body size is one of the most important characteristics of any animal because it affects a range of behavioral, ecological, and physiological traits including energy requirements, choice of food, reproductive strategies, predation risk, range size, and locomotor style. This article focuses on the implications of being large bodied for Homo erectus females, estimated to have been over 50% heavier than average australopithecine females. The energy requirements of these hominins are modeled using data on activity patterns, body mass, and life history from living primates. Particular attention is given to the inferred energetic costs of reproduction for Homo erectus females based on chimpanzee and human reproductive scheduling. Daily energy requirements during gestation and lactation would have been significantly higher for Homo erectus females, as would total energetic cost per offspring if the australopithecines and Homo erectus had similar reproductive schedules (gestation and lactation lengths and interbirth intervals). Shortening the interbirth interval could considerably reduce the costs per offspring to Homo erectus and have the added advantage of increasing reproductive output. The mother would, however, incur additional daily costs of caring for the dependent offspring. If Homo erectus females adopted this reproductive strategy, it would necessarily imply a revolution in the way in which females obtained and utilized energy to support their increased energetic requirements. This transformation is likely to have occurred on several levels involving cooperative economic division of labor, locomotor energetics, menopause, organ size, and other physiological mechanisms for reducing the energetic load on females. Am. J. Hum. Biol. 14:551,565, 2002. © 2002 Wiley-Liss, Inc. [source] Luminescence properties of the structure built from 3-cyano-4-dicyanomethylene-5-oxo-4,5-dihydro-1H -pyrrol-2-olate and caesium(I)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2010Viktor A. Tafeenko The structure of caesium(I) 3-cyano-4-dicyanomethylene-5-oxo-4,5-dihydro-1H -pyrrol-2-olate (CsA), Cs+·C8HN4O2,, is related to its luminescence properties. The structure of CsA (triclinic, P) is not isomorphous with previously reported structures (monoclinic, P21/c) of the KA and RbA salts. Nevertheless, the coordination numbers of the metals are equal for all salts (nine). Each anion in the CsA salt is connected by pairs of inversion-related N,H...O hydrogen bonds to another anion, forming a centrosymmetric dimer. The dimers are linked into infinite ribbons, stacked by means of ,,, interactions, thus building up an anionic wall. Time-dependent density functional theory calculations show that the formation of the dimer shifts the wavelength of the luminescence maximum to the blue region. Shortening the distance between stacked anions in the row [from 3.431,(5),Å for RbA to 3.388,(2),Å for KA to 3.244,(10),Å for CsA] correlates with a redshift of the luminescence maximum from 574 and 580,nm to 596,nm, respectively. [source] Structure determination of the minimal complex between Tfb5 and Tfb2, two subunits of the yeast transcription/DNA-repair factor TFIIH: a retrospective studyACTA CRYSTALLOGRAPHICA SECTION D, Issue 7 2010Denis E. Kainov Tfb5 interacts with the Tfb2 subunit of the general transcription factor TFIIH to ensure efficient nucleotide-excision repair in eukaryotes. The crystal structure of the complex between Tfb5 and the C-terminal region of Tfb2 (Tfb2C) from Saccharomyces cerevisiae has recently been reported. Here, the structure-determination process is described as a case study. Although crystals were obtained readily, it was not possible to determine experimental phases from a first crystal form (Tfb2412,513,Tfb52,72) that diffracted to 2.6,Å resolution. Shortening of the Tfb2C from its N-terminus was decisive and modified the crystal packing, leading to a second crystal form (Tfb2435,513,Tfb52,72). These crystals diffracted to 1.7,Å resolution with excellent mosaicity and allowed structure determination by conventional approaches using heavy atoms. The refined structure from the second crystal form was used to solve the structure of the first crystal form by molecular replacement. Comparison of the two structures revealed that the N-terminal region of Tfb2C and (to a lesser extent) the C-terminal region of Tfb5 contributed to the crystal packing. A detailed analysis illustrates how variation in domain boundaries influences crystal packing and quality. [source] Frontal accretion and thrust wedge evolution under very oblique plate convergence: Fiordland Basin, New ZealandBASIN RESEARCH, Issue 4 2002P. M. Barnes ABSTRACT A thrust wedge with unusual geometry has developed under very oblique (50,60°) convergence between the Pacific and Australian Plates, along the 240-km length of the Fiordland margin, New Zealand. The narrow (25 km-wide) wedge comprises three overlapping components, lying west of the offshore section of the Alpine Fault, and straddles a change of > 30° in the regional strike of the plate boundary. Swath bathymetry, marine seismic reflection profiles, and dated samples together reveal the stratigraphy, structure, and evolution of the wedge and the underthrusting, continental, Caswell High (Australian Plate). Lateral variations in the composition and structure of the accretionary wedge, and the depth of the décollement thrust, result partly from variations in crustal structure and basement relief of the underthrust plate, and from associated variations in the thickness of turbidites available for frontal accretion. In the southern Fiordland Basin the underthrust plate is undergoing flexural uplift and extension, and a thick turbidite section is available for accretion. Along-strike, a structurally elevated portion of the underthrust plate is very obliquely colliding with the central part of the accretionary wedge, the turbidite section available for accretion is condensed, and structural inversion occurs in the underthrust plate. ,Growth of the thrust wedge is inferred to have commenced in the Pliocene prior to 3 ± 1 Ma, but much of the wedge developed in the Quaternary. The spatial distribution of thrusting has varied through time, with most late Quaternary shortening occurring on structures within 10 km of the right-stepping deformation front. Estimates of the magnitude and rates of deformation indicate that the wedge accommodates a significant component of the oblique convergence between the Pacific and Australian Plates. Shortening of up to 7.3 ± 1.4 km and 9.1 ± 1.8 km within the southern and central parts of the wedge, respectively, represent about 5,15% of the total 70,140 km of shortening predicted across the plate boundary since 6.4 Ma, and about 10,30% since 3 Ma. Late Quaternary shortening rates of the order of 1,5 mm yr,1, estimated across both the northern and southern parts of the wedge, represent about 10,50 and 5,21% of the total NUVEL-1 A shortening across the plate boundary at these respective latitudes, implying that most shortening is occurring onshore. Furthermore, possible oblique-slip thrusting within the wedge may be accommodating boundary-parallel displacement of 0,6 mm yr,1, representing 0,17% of the total predicted within the plate boundary. [source] Coronary no-reflow phenomenon: From the experimental laboratory to the cardiac catheterization laboratory,CATHETERIZATION AND CARDIOVASCULAR INTERVENTIONS, Issue 7 2008Shereif H. Rezkalla MD Abstract Coronary no-reflow occurs commonly during acute percutaneous coronary intervention, particularly in patients with acute myocardial infarction and those with degenerated vein grafts. It is associated with a guarded prognosis, and thus needs to be recognized and treated promptly. The pathophysiology originates during the ischemic phase and is characterized by localized and diffuse capillary swelling and arteriolar endothelial dysfunction. In addition, leukocytes become activated and are attracted to the lumen of the capillaries, exhibit diapedesis and may contribute to cellular and intracellular edema and clogging of vessels. At the moment of perfusion, the sudden rush of leukocytes and distal atheroemboli further contributes to impaired tissue perfusion. Shortening the door-to-balloon time, use of glycoprotein IIb/IIIa platelet receptor inhibitors and distal protection devices are predicted to limit the development of no-reflow during percutaneous interventions. Distal intracoronary injection of verapamil, nicardipine, adenosine, and nitroprusside may improve coronary flow in the majority of patients. Hemodynamic support of the patient may be needed in some cases until coronary flow improves. © 2008 Wiley-Liss, Inc. [source] Virtuelle Produktmodellierung am Beispiel eines PumpenlaufradesCHEMIE-INGENIEUR-TECHNIK (CIT), Issue 1-2 2003F.-K. Benra Dr.-Ing. Abstract Durch die Verkürzung der Produktlebenszyklen werden die zur Verfügung stehenden Entwicklungszeiten entscheidend eingeschränkt. Es bleibt keine Zeit mehr für ein umfangreiches Erprobungsprogramm, bei dem die gewünschten Produkteigenschaften durch die Untersuchung und Abwandlung diverser Prototypen erzielt werden. Durch konsequenten Einsatz virtueller Techniken ist die Simulation der geforderten Produkteigenschaften und des Herstellungsprozesses möglich. Das Ergebnis einer so aufgebauten CAx-Prozesskette ist eine vollständige, durchgängig rechnerintegrierte Bauteilentwicklung. In diesem Beitrag wird ein derartiger Produktentstehungsprozess am Beispiel eines Kreiselpumpenlaufrades detailliert beschrieben. Durch die Schaffung eines Anwendungssystems für die Berechnung, Konstruktion und Fertigung von Pumpenlaufrädern lässt sich der Entwicklungsprozess enorm verkürzen. Gleichzeitig ist damit eine wesentliche Senkung der Entwicklungskosten für ein äußerst effektives und zuverlässiges Produkt verbunden. Virtual Modeling of Products with a Centrifugal Pump Impeller as an Example Shortening of the product life cycles means less time for the development of a technical product. There is no more time for an extensive testing program to obtain the desired product properties by investigation and modification of various prototypes. By careful application of virtual techniques the simulation of the required product properties and the production process is possible. The result of a CAx-System is a complete computer-integrated construction unit development. In this contribution the product developing process is described in detail for a centrifugal pump impeller. The creation of an application system for the computation, construction and manufacturing of pump impellers shortens the development process enormously. At the same time the development costs for an extremely effective and reliable product become substantially lower. [source] Changes in left ventricular ejection time and pulse transit time derived from finger photoplethysmogram and electrocardiogram during moderate haemorrhageCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 3 2009Paul M. Middleton Summary Objectives:, Early identification of haemorrhage is difficult when a bleeding site is not apparent. This study explored the potential use of the finger photoplethysmographic (PPG) waveform derived left ventricular ejection time (LVETp) and pulse transit time (PTT) for detecting blood loss, by using blood donation as a model of controlled mild to moderate haemorrhage. Methods:, This was a prospective, observational study carried out in a convenience sample of blood donors. LVETp, PTT and R-R interval (RRi) were computed from simultaneous measurement of the electrocardiogram (ECG) and the finger infrared photoplethysmogram obtained from 43 healthy volunteers during blood donation. The blood donation process was divided into four stages: (i) Pre-donation (PRE), (ii) first half of donation (FIRST), (iii) second half of donation (SECOND), (iv) post-donation (POST). Results and conclusions:, Shortening of LVETp from 303+/,2 to 293+/,3 ms (mean+/,SEM; P<0·01) and prolongation of PTT from 177+/,3 to 186+/,4 ms (P<0·01) were observed in 81% and 91% of subjects respectively when comparing PRE and POST. During blood donation, progressive blood loss produced falling trends in LVETp (P<0·01) and rising trends in PTT (P<0·01) in FIRST and SECOND, but a falling trend in RRi (P<0·01) was only observed in SECOND. Monitoring trends in timing variables derived from non-invasive ECG and finger PPG signals may facilitate detection of blood loss in the early phase. [source] Molecular characterization of regenerated cardiomyocytes derived from adult mesenchymal stem cellsCONGENITAL ANOMALIES, Issue 1 2002Keiichi Fukuda ABSTRACT, We recently isolated a cardiomyogenic (CMG) cell line from murine bone marrow stroma, and in this paper characterize regenerated cardiomyocytes derived from adult mesenchymal stem cells at the molecular level. Stromal cells were immortalized, exposed to 5-azacytidine, and repeatedly screened for spontaneously beating cells. CMG cells began to beat spontaneously after 2 weeks, and beat synchronously after 3 weeks. They exhibited sinus-node-like or ventricular-cell-like action potentials. Analysis of the isoforms of contractile protein genes, such as of myosin and ,-actin, indicated that their phenotype was similar to that of fetal ventricular cardiomyocytes. The cells expressed Nkx2.5, GATA4, TEF-1, and MEF2-C mRNA before 5-azacytidine exposure, and MEF2-A and MEF2-D after exposure. CMG cells expressed ,1A, ,1B, and ,1D -adrenergic receptor mRNA prior to differentiation, and ,1, ,2 -adrenergic and M1, M2 -muscarinic receptors after acquiring the cardiomyocyte phenotype. Phenylephrine induced phosphorylation of ERK1/ 2, and the phosphorylation was inhibited by prazosin. Isoproterenol increased the cAMP level 38-fold and beating rate, cell motion, % shortening, and contractile velocity by 48%, 38%, 27%, and 51%, respectively, and the increases were blocked by CGP20712A (,1 -selective blocker). Car-bachol increased IP3 32-fold, and the increase was inhibited by AFDX116 (M2 -selective blocker). These findings demonstrated that the regenerated cardiomyocytes were capable of responding to adrenergic and muscarinic stimulation. This new cell line provides a model for the study of cardiomyocyte transplantation. [source] Vastus lateralis surface and single motor unit electromyography during shortening, lengthening and isometric contractions corrected for mode-dependent differences in force-generating capacityACTA PHYSIOLOGICA, Issue 3 2009T. M. Altenburg Abstract Aim:, Knee extensor neuromuscular activity, rectified surface electromyography (rsEMG) and single motor unit EMG was investigated during isometric (60° knee angle), shortening and lengthening contractions (50,70°, 10° s,1) corrected for force,velocity-related differences in force-generating capacity. However, during dynamic contractions additional factors such as shortening-induced force losses and lengthening-induced force gains may also affect force capacity and thereby neuromuscular activity. Therefore, even after correction for force,velocity-related differences in force capacity we expected neuromuscular activity to be higher and lower during shortening and lengthening, respectively, compared to isometric contractions. Methods:, rsEMG of the three superficial muscle heads was obtained in a first session [10 and 50% maximal voluntary contraction (MVC)] and additionally EMG of (46) vastus lateralis motor units was recorded during a second session (4,76% MVC). Using superimposed electrical stimulation, force-generating capacity for shortening and lengthening contractions was found to be 0.96 and 1.16 times isometric (Iso) force capacity respectively. Therefore, neuromuscular activity during submaximal shortening and lengthening was compared with isometric contractions of respectively 1.04Iso (=1/0.96) and 0.86Iso (=1/1.16). rsEMG and discharge rates were normalized to isometric values. Results:, rsEMG behaviour was similar (P > 0.05) during both sessions. Shortening rsEMG (1.30 ± 0.11) and discharge rate (1.22 ± 0.13) were higher (P < 0.05) than 1.04Iso values (1.05 ± 0.05 and 1.03 ± 0.04 respectively), but lengthening rsEMG (1.05 ± 0.12) and discharge rate (0.90 ± 0.08) were not lower (P > 0.05) than 0.86Iso values (0.76 ± 0.04 and 0.91 ± 0.07 respectively). Conclusion:, When force,velocity-related differences in force capacity were taken into account, neuromuscular activity was not lower during lengthening but was still higher during shortening compared with isometric contractions. [source] Metabolic cost of lengthening, isometric and shortening contractions in maximally stimulated rat skeletal muscleACTA PHYSIOLOGICA, Issue 2 2004J. G. M. Beltman Abstract Aim:, The present study investigated the energy cost of lengthening, isometric and shortening contractions in rat muscle (n = 19). Methods:, With electrical stimulation the rat medial gastrocnemius muscle was maximally stimulated to perform 10 lengthening, isometric and shortening contractions (velocity 25 mm s,1) under experimental conditions (e.g. temperature, movement velocity) that resemble conditions in human movement. Results:, Mean ± SD force,time-integral of the first contraction was significantly different between the three protocols, 2.4 ± 0.2, 1.7 ± 0.2 and 1.0 ± 0.2 N s, respectively (P < 0.05). High-energy phosphate consumption was not significantly different between the three modes of exercise but a trend could be observed from lengthening (7.7 ± 2.7 ,mol , P muscle,1) to isometric (8.9 ± 2.2 ,mol , P muscle,1) to shortening contractions (10.4 ± 1.6 ,mol , P muscle,1). The ratio of high-energy phosphate consumption to force,time-integral was significantly lower for lengthening [0.3 ± 0.1 ,mol , P (N s),1] and isometric [0.6 ± 0.2 ,mol , P (N s),1] contractions compared with shortening [1.2 ± 0.2 ,mol , P (N s),1] contractions (P < 0.05). Conclusion:, The present results of maximally stimulated muscles are comparable with data in the literature for voluntary human exercise showing that the energy cost of force production during lengthening exercise is ,30% of that in shortening exercise. The present study suggests that this finding in humans probably does reflect intrinsic muscle properties rather than effects of differential recruitment and/or coactivation. [source] Adenosine induces prolonged anti-,-adrenergic effects in guinea-pig papillary muscleACTA PHYSIOLOGICA, Issue 1 2002L. ARVOLA ABSTRACT A sustained anti- , -adrenergic effect of adenosine has been reported. This study was initiated to investigate this topic and especially elucidate the role of protein kinase C (PKC). Contractile force amplitude and action potential duration at 90% repolarization (APD90) were measured in guinea-pig papillary muscles before and after 5 min challenge with 5 nm isoproterenol. Protocols contained 30 min exposure to the test agents adenosine 33 ,m (ado), adenosine + PKC-inhibitor bisindolylmaleimide 20 nM (ado + BIM), PKC-activator 1,2-dioctanoyl-sn-glycerol 10 ,m (DOG) and , -agonist phenylephrine 5 ,m (phe). Isoproterenol was given at the end of test exposure and after 15 min washout. Results are mean ± SEM of percentage-change, P , 0.05 considered significant and labelled *. The first isoproterenol challenge significantly increased contractile force (27 ± 7%*) in the control group. Responses in the test groups were 2 ± 4 (ado), 1 ± 5 (ado + BIM), 14 ± 4* (DOG), 0 ± 2% (phe). After washout of adenosine, DOG and phenylephrine, isoproterenol induced 3 ± 8 (ado), 23 ± 5* (ado + BIM), 13 ± 5* (DOG), 15 ± 7% (phe) increase in test groups compared with 22 ± 5%* increase in contractile force in the control group. After 45 min washout of adenosine the inotropic response was still significantly reduced compared with control (29 ± 4 vs. 79 ± 8%*). Isoproterenol stimulation shortened APD90 in controls at both time points (5 ± 1%* and 4 ± 1%*), with no significant shortening in test groups. Adenosine induces sustained anti- , -adrenergic effects on contractile force as well as APD90. A role for PKC in signal transduction is supported with respect to contractile force. [source] Actin stress fiber pre-extension in human aortic endothelial cellsCYTOSKELETON, Issue 4 2008Lan Lu Abstract Actin stress fibers (SFs) enable cells to sense and respond to mechanical stimuli and affect adhesion, motility and apoptosis. We and others have demonstrated that cultured human aortic endothelial cells (HAECs) are internally stressed so that SFs are pre-extended beyond their unloaded lengths. The present study explores factors affecting SF pre-extension. In HAECs cultured overnight the baseline pre-extension was 1.10 and independent of the amount of cell shortening. Decreasing contractility with 30 mM BDM or 10 ,M blebbistatin decreased pre-extension to 1.05 whereas increasing contractility with 2 nM calyculin A increased pre-extension to 1.26. Knockdown of ,-actinin-1 with an interfering RNA increased pre-extension to 1.28. None of these affected the wavelength of the buckled SFs. Pre-extension was the same in unperturbed cells as in those in which the actin cytoskeleton was disrupted by both chemical and mechanical means and then allowed to reassemble. Finally, disrupting MTs or IFs did not affect pre-extension but increased the wavelength. Taken together, these results suggest that pre-extension of SFs is determined primarily by intrinsic factors, i.e. the level of actin-myosin interaction. This intrinsic control of pre-extension is sufficiently robust that pre-extension is the same even after the actin cytoskeleton has been disrupted and reorganized. Unlike pre-extension, the morphology of the compressed SFs is partially determined by MTs and IFs which appear to support the SFs along their lengths. Cell Motil. Cytoskeleton 2008. © 2008 Wiley-Liss, Inc. [source] Early molecular events in the assembly of the focal adhesion-stress fiber complex during fibroblast spreadingCYTOSKELETON, Issue 3 2004Baruch Zimerman Cell adhesion to the extracellular matrix triggers the formation of integrin-mediated contact and reorganization of the actin cytoskeleton. Examination of nascent adhesions, formed during early stages of fibroblast spreading, reveals a variety of forms of actin-associated matrix adhesions. These include: (1) small (,1 ,m), dot-like, integrin-, vinculin-, paxillin-, and phosphotyrosine-rich structures, with an F-actin core, broadly distributed over the ventral surfaces of the cells; (2) integrin-, vinculin-, and paxillin-containing "doublets" interconnected by short actin bundles; (3) arrays of actin-vinculin complexes. Such structures were formed by freshly plated cells, as well as by cells recovering from latrunculin treatment. Time-lapse video microscopy of such cells, expressing GFP-actin, indicated that long actin cables are formed by an end-to-end lining-up and apparent fusion of short actin bundles. All these structures were prominent during cell spreading, and persisted for up to 30,60 min after plating. Upon longer incubation, they were gradually replaced by stress fibers, associated with focal adhesions at the cell periphery. Direct examination of paxillin and actin reorganization in live cells revealed alignment of paxillin doublets, forming long and highly dynamic actin bundles, undergoing translocation, shortening, splitting, and convergence. The mechanisms underlying the assembly and reorganization of actin-associated focal adhesions and the involvement of mechanical forces in regulating their dynamic properties are discussed. Cell Motil. Cytoskeleton 58:143,159, 2004. © 2004 Wiley-Liss, Inc. [source] | |||||||||||||||||||||||||||||||||||||