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Improved cardiac filling facilitates the postprandial elevation of stroke volume in Python regius RESEARCH ARTICLE
Sanne Enok, Gabriella Leite, Cleo Leite, Hans Gesser, Michael S. Hedrick, and Tobias WangTo accommodate the pronounced metabolic response to digestion, pythons increase both heart rate and elevate stroke volume, where the latter has been ascribed to a massive and fast cardiac hypertrophy. However, numerous recent studies show that heart mass rarely increases even upon ingestion of large meals, and we therefore explored the possibility that a rise in mean circulatory filling pressure (MCFP) serves to elevate venous pressure and cardiac filling during digestion. To this end, we measured blood flows and pressures in anaesthet...
Source: Journal of Experimental Biology - July 20, 2016 Category: Biology Authors: Enok, S., Leite, G., Leite, C., Gesser, H., Hedrick, M. S., Wang, T. Tags: RESEARCH ARTICLE Source Type: research

Stem Cells for Cell-Based Therapies
The world of stem cells We know the human body comprises many cell types (e.g., blood cells, skin cells, cervical cells), but we often forget to appreciate that all of these different cell types arose from a single cell—the fertilized egg. A host of sequential, awe-inspiring events occur between the fertilization of an egg and the formation of a new individual: Embryonic stem (ES) cells are also called totipotent cells. The first steps involve making more cells by simple cell division: one cell becomes two cells; two cells become four cells, etc. Each cell of early development is undifferentiated; that is, it is...
Source: ActionBioscience - December 28, 2012 Category: Biology Authors: Ali Hochberg Source Type: news

Cardiovascular responses to progressive hypoxia in ducks native to high altitude in the Andes RESEARCH ARTICLE
Sabine L. Lague, Catherine M. Ivy, Julia M. York, Beverly A. Chua, Luis Alza, Rebecca Cheek, Neal J. Dawson, Peter B. Frappell, Anthony P. Farrell, Kevin G. McCracken, Graham R. Scott, and William K. Milsom The cardiovascular system is critical for delivering O2 to tissues. Here we examine the cardiovascular responses to progressive hypoxia in four high-altitude Andean duck species compared to four related low-altitude populations in North America, tested at their native altitude. Ducks were exposed to stepwise decreases in inspired partial pressure of O2 while we monitored heart rate, O2 consumption rate, blood O2 saturat...
Source: Journal of Experimental Biology - February 9, 2020 Category: Biology Authors: Lague, S. L., Ivy, C. M., York, J. M., Chua, B. A., Alza, L., Cheek, R., Dawson, N. J., Frappell, P. B., Farrell, A. P., McCracken, K. G., Scott, G. R., Milsom, W. K. Tags: RESEARCH ARTICLE Source Type: research

Thermal and hemodynamic response to whole-body cryostimulation in healthy subjects.
In conclusion, the present findings suggest that WBC strongly stimulates the baroreceptor cardiac reflex in response to body fluid changes which sequentially modulate HR and BP control in supine and resting healthy subjects. The study was performed on randomized and homogenic group of young healthy subjects. Our findings are important for WBC safety determination in research and clinical studies. PMID: 23535554 [PubMed - in process]
Source: Cryobiology - May 23, 2013 Category: Biology Authors: Zalewski P, Klawe JJ, Pawlak J, Tafil-Klawe M, Newton J Tags: Cryobiology Source Type: research

Arterial Stiffening Provides Sufficient Explanation for Primary Hypertension
by Klas H. Pettersen, Scott M. Bugenhagen, Javaid Nauman, Daniel A. Beard, Stig W. Omholt Hypertension is one of the most common age-related chronic disorders, and by predisposing individuals for heart failure, stroke, and kidney disease, it is a major source of morbidity and mortality. Its etiology remains enigmatic despite intense research efforts over many decades. By use of empirically well-constrained computer models describing the coupled function of the baroreceptor reflex and mechanics of the circulatory system, we demonstrate quantitatively that arterial stiffening seems sufficient to explain age-related emergenc...
Source: PLoS Computational Biology - May 22, 2014 Category: Biology Authors: Klas H. Pettersen et al. Source Type: research

Pitch perfect: how fruit flies control their body pitch angle RESEARCH ARTICLE
Samuel C. Whitehead, Tsevi Beatus, Luca Canale, and Itai CohenFlapping insect flight is a complex and beautiful phenomenon that relies on fast, active control mechanisms to counter aerodynamic instability. To directly investigate how freely-flying D. melanogaster control their body pitch angle against such instability, we perturb them using impulsive mechanical torques and film their corrective maneuvers with high-speed video. Combining experimental observations and numerical simulation, we find that flies correct for pitch deflections of up to 40° in 29±8 ms by bilaterally modulating their wings' front-most str...
Source: Journal of Experimental Biology - September 18, 2015 Category: Biology Authors: Whitehead, S. C., Beatus, T., Canale, L., Cohen, I. Tags: RESEARCH ARTICLE Source Type: research

Winter metabolic depression does not change arterial baroreflex control of heart rate in the tegu lizard (Salvator merianae) RESEARCH ARTICLE
Lucas A. Zena, Valter Dantonio, Luciane H. Gargaglioni, Denis V. Andrade, Augusto S. Abe, and Kenia C. BicegoBaroreflex regulation of blood pressure (BP) is important for maintaining appropriate tissue perfusion. Although temperature affects heart rate (fH) reflex regulation in some reptiles and toads, no data are available on the influence of temperature-independent metabolic states on baroreflex. The South American tegu lizard Salvator merianae exhibits a clear seasonal cycle of activity decreasing fH along with winter metabolic downregulation, independent of body temperature. Through pharmacological interventions (pheny...
Source: Journal of Experimental Biology - January 8, 2016 Category: Biology Authors: Zena, L. A., Dantonio, V., Gargaglioni, L. H., Andrade, D. V., Abe, A. S., Bicego, K. C. Tags: RESEARCH ARTICLE Source Type: research

Winter metabolic depression does not change arterial baroreflex control of heart rate in the tegu lizard Salvator merianae RESEARCH ARTICLE
Lucas A. Zena, Valter Dantonio, Luciane H. Gargaglioni, Denis V. Andrade, Augusto S. Abe, and Kenia C. Bicego Baroreflex regulation of blood pressure is important for maintaining appropriate tissue perfusion. Although temperature affects heart rate (fH) reflex regulation in some reptiles and toads, no data are available on the influence of temperature-independent metabolic states on baroreflex. The South American tegu lizard Salvator merianae exhibits a clear seasonal cycle of activity decreasing fH along with winter metabolic downregulation, independent of body temperature. Through pharmacological interventions (phenyleph...
Source: Journal of Experimental Biology - March 2, 2016 Category: Biology Authors: Zena, L. A., Dantonio, V., Gargaglioni, L. H., Andrade, D. V., Abe, A. S., Bicego, K. C. Tags: RESEARCH ARTICLE Source Type: research

Predicting gait adaptations due to ankle plantarflexor muscle weakness and contracture using physics-based musculoskeletal simulations
by Carmichael F. Ong, Thomas Geijtenbeek, Jennifer L. Hicks, Scott L. Delp Deficits in the ankle plantarflexor muscles, such as weakness and contracture, occur commonly in conditions such as cerebral palsy, stroke, muscular dystrophy, Charcot-Marie-Tooth disease, and sarcopenia. While these deficits likely contribute to observed gait pathologies, determining cause-effect relationships is difficult due to the often co-occurring biomechanical and neural deficits. To elucidate the effects of weakness and contracture, we systematically introduced isolated deficits into a musculoskeletal model and generated simulations of walk...
Source: PLoS Computational Biology - October 6, 2019 Category: Biology Authors: Carmichael F. Ong Source Type: research

How do hoverflies use their righting reflex? RESEARCH ARTICLE
Anna Verbe, Leandre P. Varennes, Jean-Louis Vercher, and Stephane Viollet When taking off from a sloping surface, flies have to reorient themselves dorsoventrally and stabilize their body by actively controlling their flapping wings. We have observed that the righting is achieved solely by performing a rolling manoeuvre. How flies manage to do this has not yet been elucidated. It was observed here for the first time that hoverflies’ reorientation is entirely achieved within 6 wingbeats (48.8ms) at angular roll velocities of up to 10x103 °/s and that the onset of their head rotation consistently follows that of th...
Source: Journal of Experimental Biology - June 10, 2020 Category: Biology Authors: Verbe, A., Varennes, L. P., Vercher, J.-L., Viollet, S. Tags: RESEARCH ARTICLE Source Type: research