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Preload reserve

Jae Hyun Bae, Lee Kyung Kim, Se Hee Min, Chang Ho Ahn, Young Min Cho
AIMS/INTRODUCTION: Protein preload improves postprandial glycemia by stimulating secretion of insulin and incretin hormones. However, it requires a large dose of protein to produce a significant effect. This study was conducted to investigate the postprandial glucose-lowering effect of premeal protein-enriched, dietary fiber-fortified bar (PFB), which contains moderate amounts of protein, in subjects with type 2 diabetes mellitus (T2D) or normal glucose tolerance (NGT). MATERIALS AND METHODS: The participants (15 T2D and 15 NGT) were randomly assigned to either a premeal or postmeal PFB group and underwent two mixed meal tolerance tests (MMTTs), 1 week apart in reverse order...
March 4, 2018: Journal of Diabetes Investigation
Karl-Philipp Rommel, Maximilian von Roeder, Christian Oberueck, Konrad Latuscynski, Christian Besler, Stephan Blazek, Thomas Stiermaier, Karl Fengler, Volker Adams, Marcus Sandri, Axel Linke, Gerhard Schuler, Holger Thiele, Philipp Lurz
BACKGROUND: Although systolic right ventricular (RV) dysfunction has been shown to be a potent predictor for adverse outcomes in patients with heart failure with preserved ejection fraction (HFpEF), RV functional abnormalities in the course of the syndrome are not well characterized. We, therefore, sought to assess load-independent and load-dependent systolic and diastolic characteristics of RV function in stable outpatients with HFpEF. METHODS AND RESULTS: We invasively obtained RV and left ventricular pressure-volume loops in 24 HFpEF patients and 9 patients without heart failure symptoms with a conductance catheter during basal conditions and handgrip exercise...
February 2018: Circulation. Heart Failure
Semih E Bezci, Ananth Eleswarapu, Eric O Klineberg, Grace D O'Connell
Stresses applied to the spinal column are distributed between the intervertebral disc and facet joints. Structural and compositional changes alter stress distributions within the disc and between the disc and facet joints. These changes influence the mechanical properties of the disc joint, including its stiffness, range of motion, and energy absorption under quasi-static and dynamic loads. There have been few studies evaluating the role of facet joints in torsion. Furthermore, the relationship between biochemical composition and torsion mechanics is not well understood...
February 12, 2018: Journal of Orthopaedic Research: Official Publication of the Orthopaedic Research Society
Rachel Lord, David MacLeod, Keith George, David Oxborough, Rob Shave, Mike Stembridge
An acute non-invasive reduction in preload has been shown to augment cardiac mechanics to maintain stroke volume and cardiac output. Such interventions induce concomitant changes in heart rate (HR), whereas blood volume extraction reduces preload without HR changes. Therefore, the purpose of this study was to determine whether a preload reduction in isolation resulted in augmented stroke volume achieved via enhanced cardiac mechanics. Nine healthy volunteers (4 female, age 29 ± 11 years) underwent echocardiography for the assessment of left ventricular (LV) volumes and mechanics in a supine position at baseline and end-extraction following the controlled removal of 25% of total blood volume (1062 ± 342 ml)...
January 18, 2018: Experimental Physiology
M M Nikitin, N V Statsyuk, P A Frantsuzov, V G Dzhavakhiya, A G Golikov
AIM: Create a method for highly sensitive, selective, rapid, and easy-to-use detection and identification of economically significant potato pathogens, including viruses, bacteria and oomycetes, be it single pathogen, or a range of various pathogens occurring simultaneously. METHODS AND RESULTS: Test-systems for real-time PCR, operating in the unified amplification regime, have been developed for Phytophthora infestans, Pectobacterium atrosepticum, Dickeya dianthicola, Dickeya solani, Ralstonia solanacearum, Pectobacterium carotovorum, Clavibacter michiganensis subsp...
January 3, 2018: Journal of Applied Microbiology
Toan Pham, June-Chiew Han, Andrew Taberner, Denis Loiselle
KEY POINTS: We designed a study to test whether velocity of shortening in right-ventricular tissue preparations is greater than that of the left side under conditions mimicking those encountered by the heart in vivo. Our experiments allowed us to explore whether greater velocity of shortening results in any energetic advantage. We found that velocity of shortening was higher in the rat right-ventricular trabeculae. These results at the tissue level seem paradoxical to the velocity of ventricular ejection at the organ level, and are not always in accord with shortening of unloaded cells...
October 15, 2017: Journal of Physiology
Younes Boudjemline, Aleksander Sizarov, Sophie Malekzadeh-Milani, Cristian Mirabile, Marien Lenoir, Diala Khraiche, Marilyne Lévy, Damien Bonnet
BACKGROUND: The reversed Potts shunt improves right ventricular (RV) function in patients with suprasystemic pulmonary arterial hypertension (PAH). The proximity of the left pulmonary artery (LPA) to the descending aorta (DAo) permits the creation of a transcatheter connection. We sought to assess the safety, feasibility, and hemodynamic efficacy of the transcatheter Potts shunt (TPS) in children. METHODS: The TPS procedure was performed using radiofrequency energy for vessel perforation and deployment of a covered stent to connect the DAo and LPA...
September 2017: Canadian Journal of Cardiology
Michael R Pinsky
The hemodynamic effects of ventilation can be grouped into three concepts: 1) spontaneous ventilation is exercise; 2) changes in lung volume alter autonomic tone, pulmonary vascular resistance, and can compress the heart in the cardiac fossa; 3) spontaneous inspiratory efforts decrease intrathoracic pressure (ITP) increasing venous return and impeding left ventricular (LV) ejection; whereas positive pressure ventilation decreases venous return and unloads LV ejection. Spontaneous inspiratory efforts may induce acute LV failure and cardiogenic pulmonary edema...
August 18, 2017: Annals of the American Thoracic Society
Junjing Su, Charlotte Manisty, Ulf Simonsen, Luke S Howard, Kim H Parker, Alun D Hughes
KEY POINTS: Wave travel plays an important role in cardiovascular physiology. However, many aspects of pulmonary arterial wave behaviour remain unclear. Wave intensity and reservoir-excess pressure analyses were applied in the pulmonary artery in subjects with and without pulmonary hypertension during spontaneous respiration and dynamic stress tests. Arterial wave energy decreased during expiration and Valsalva manoeuvre due to decreased ventricular preload. Wave energy also decreased during handgrip exercise due to increased heart rate...
October 15, 2017: Journal of Physiology
Hiroki Matsuzoe, Kensuke Matsumoto, Hidekazu Tanaka, Yutaka Hatani, Keiko Hatazawa, Hiroyuki Shimoura, Junichi Ooka, Hiroyuki Sano, Keiko Ryo-Koriyama, Toshiro Shinke, Hirotsugu Yamada, Yutaka Okita, Ken-Ichi Hirata
BACKGROUND: Although aortic valve intervention is recommended for virtually all symptomatic patients with aortic stenosis (AS), how urgently the intervention should be performed remains controversial. The aim of this study was thus to determine whether the preload reserve in response to leg-positive pressure (LPP) maneuver could serve for decision-making for AS patients awaiting aortic valve intervention.Methods and Results:Sixty-eight patients with symptomatic AS, who were referred for aortic valve intervention, were recruited...
November 24, 2017: Circulation Journal: Official Journal of the Japanese Circulation Society
Naoaki Okura, Yuta Nakashoji, Toshihiro Koshirogane, Masaki Kondo, Yugo Tanaka, Kohei Inoue, Masahiko Hashimoto
We have exploited a compact and facile microfluidic droplet creation device consisting of a poly(dimethylsiloxane) microfluidic chip possessing T-junction channel geometry, two inlet reservoirs, and one outlet reservoir, and a piezoelectric (PZT) diaphragm micropump with controller. Air was evacuated from the outlet reservoir using the PZT pump, reducing the pressure inside. The reduced pressure within the outlet reservoir pulled oil and aqueous solution preloaded in the inlet reservoirs into the microchannels, which then merged at the T-junction, successfully forming water-in-oil emulsion droplets at a rate of ∼1000 per second with minimal sample loss...
October 2017: Electrophoresis
Lei Zhang, Nicolas A Turpin, Anatol G Feldman
KEY POINTS: Sudden unloading of preloaded wrist muscles elicits motion to a new wrist position. Such motion is prevented if subjects unload muscles using the contralateral arm (self-unloading). Corticospinal influences originated from the primary motor cortex maintain tonic influences on motoneurons of wrist muscles before sudden unloading but modify these influences prior to the onset and until the end of self-unloading. Results are interpreted based on the previous finding that intentional actions are caused by central, particularly corticospinal, shifts in the spatial thresholds at which wrist motoneurons are activated, thus predetermining the attractor point at which the neuromuscular periphery achieves mechanical balance with environment forces...
August 1, 2017: Journal of Physiology
Paolo T Pianosi, Eric Emerling, Kristin C Mara, Amy L Weaver, Philip R Fischer
Females demonstrate less robust Frank-Starling mechanism with respect to cardiac preload than males at rest. We asked whether this phenomenon would also affect cardiac performance during exercise. We hypothesized that stroke volume (SV) response to exercise would be more limited in deconditioned females such that cardiac output would be mainly rate dependent, compared with males. We conducted a chart audit of clinical exercise tests performed by adolescents with chronic fatigue. Oxygen uptake (VO2 ) was measured breath-by-breath at rest and during cycle ergometry, while cardiac output was measured by acetylene rebreathing at rest plus 2-3 sub-threshold workloads...
May 24, 2017: Scandinavian Journal of Medicine & Science in Sports
Michael D Nelson, Puja K Mehta, Janet Wei, Behzad Sharif, Louise E J Thomson, Daniel Berman, Debiao Li, C Noel Bairey Merz
BACKGROUND: Ischemia, in the absence of obstructive coronary artery disease, is prevalent in women, and associated with increased risk for major cardiovascular events. Coronary microvascular dysfunction is prevalent in these patients, and associated with impaired diastolic function. Despite our general understanding, however, optimal treatment of this cohort remains elusive. METHODS: To address this knowledge gap, we performed an open-label treatment trial to assess whether phosphodiesterase type 5 inhibition improves coronary microvascular perfusion and diastolic function in women with signs and symptoms of ischemia but no evidence of obstructive coronary artery disease...
May 22, 2017: Journal of Medical Case Reports
Volker Schulze, Christian Meyer, Christian Eickholt, Roberto Sansone, Stefanie Keymel, Christian Heiss, Tienush Rassaf, Malte Kelm, Stephan Steiner
BACKGROUND: Increased augmentation index (AIx) is accompanied by an elevated cardiovascular risk. A reduction of AIx is known for long-term continuous positive airway pressure (CPAP) therapy. We hypothesised that acute preload and left ventricular workload effects AIx and subendocardial viability ratio (SEVR) as a marker of coronary flow reserve. METHODS: Increased augmentation index and central blood pressure parameters were measured by radial artery tonometry in 17 healthy men (32/±6years) at rest and during CPAP ventilation at pressures of 5, 10mbar and after recovery...
March 31, 2017: Heart, Lung & Circulation
Hongqun Liu, Saumya Jayakumar, Mouhieddin Traboulsi, Samuel S Lee
The majority of patients on a waiting list for liver transplantation have end-stage liver disease. Because of the marked peripheral vasodilatation of end-stage cirrhosis that masks a latent myocardial dysfunction, cardiac abnormalities in the resting state are usually subclinical and escape the attention of physicians. However, when challenged, the systolic and diastolic contractile responses are attenuated. In addition to these contractile abnormalities, morphological changes, such as enlargement or hypertrophy of cardiac chambers, and electrophysiological repolarization changes, including a prolonged QT interval, can be observed...
June 2017: Liver Transplantation
Raquel Yotti, Cristina Ripoll, Yolanda Benito, Maria Vega Catalina, Jaime Elízaga, Diego Rincón, Francisco Fernández-Avilés, Javier Bermejo, Rafael Bañares
An accurate evaluation of cardiac function in patients with cirrhosis remains a challenge. We used robust echocardiographic indices to characterize left ventricular (LV) systolic function and its relationship to activation of the sympathetic nervous system and inflammation in 59 patients with cirrhosis and 59 age-matched controls. Additionally, in 11 patients we withdrew beta-blockers and diuretics and used phenylephrine and albumin infusion to evaluate the response to acute afterload and preload changes (interventional substudy)...
June 2017: Hepatology: Official Journal of the American Association for the Study of Liver Diseases
S Li, S Korkmaz-Icöz, T Radovits, M Ruppert, R Spindler, S Loganathan, P Hegedűs, P Brlecic, B Theisinger, S Theisinger, S Höger, M Brune, F Lasitschka, M Karck, B Yard, G Szabó
Heart transplantation is the therapy of choice for end-stage heart failure. However, hemodynamic instability, which has been demonstrated in brain-dead donors (BDD), could also affect the posttransplant graft function. We tested the hypothesis that treatment of the BDD with the dopamine derivate n-octanoyl-dopamine (NOD) improves donor cardiac and graft function after transplantation. Donor rats were given a continuous intravenous infusion of either NOD (0.882 mg/kg/h, BDD+NOD, n = 6) or a physiological saline vehicle (BDD, n = 9) for 5 h after the induction of brain death by inflation of a subdural balloon catheter...
July 2017: American Journal of Transplantation
Han-Jun Wang, George J Rozanski, Irving H Zucker
KEY POINTS: Cardiac sympathetic afferents are considered to be essential pathways for transmission of cardiac nociception to the central nervous system during myocardial ischaemia. However, a potential contribution of the CSAR control of cardiac dysfunction in both normal and chronic heart failure (CHF) states remains unknown. We found that activation of the CSAR evokes little increase in cardiac contractility with an exaggerated peripheral vasoconstriction in the CHF state. CSAR inhibition by epicardial lidocaine decreased cardiac contractility to a greater extent in CHF rats than sham rats...
April 15, 2017: Journal of Physiology
Ye Chen-Izu, Leighton T Izu
The heart has the ability to adjust to changing mechanical loads. The Frank-Starling law and the Anrep effect describe exquisite intrinsic mechanisms the heart has for autoregulating the force of contraction to maintain cardiac output under changes of preload and afterload. Although these mechanisms have been known for more than a century, their cellular and molecular underpinnings are still debated. How does the cardiac myocyte sense changes in preload or afterload? How does the myocyte adjust its response to compensate for such changes? In cardiac myocytes Ca2+ is a crucial regulator of contractile force and in this review we compare and contrast recent studies from different labs that address these two important questions...
June 15, 2017: Journal of Physiology
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