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https://www.readbyqxmd.com/read/29351591/could-seasonally-deteriorating-environments-favour-the-evolution-of-autogamous-selfing-and-a-drought-escape-physiology-through-indirect-selection-a-test-of-the-time-limitation-hypothesis-using-artificial-selection-in-clarkia
#1
Simon K Emms, Alisa A Hove, Leah S Dudley, Susan J Mazer, Amy S Verhoeven
Background and Aims: The evolution of selfing from outcrossing may be the most common transition in plant reproductive systems and is associated with a variety of ecological circumstances and life history strategies. The most widely discussed explanation for these associations is the reproductive assurance hypothesis - the proposition that selfing is favoured because it increases female fitness when outcross pollen receipt is limited. Here an alternative explanation, the time limitation hypothesis, is addressed, one scenario of which proposes that selfing may evolve as a correlated response to selection for a faster life cycle in seasonally deteriorating environments...
January 17, 2018: Annals of Botany
https://www.readbyqxmd.com/read/29351473/sympathetically-mediated-cardiac-responses-to-isolated-muscle-metaboreflex-activation-following-exercise-are-modulated-by-body-position-in-humans
#2
André L Teixeira, Mauricio Daher, Mayara Souza, Plinio Santos Ramos, James P Fisher, Lauro C Vianna
Isolated muscle metaboreflex activation with post-handgrip exercise ischemia (PEI) increases sympathetic nerve activity and partially maintains the exercise-induced increase in blood pressure, but a smaller heart rate (HR) response occurs. The cardiopulmonary baroreceptors, mechanically sensitive receptors that respond to changes in central blood volume and pressure, are strongly associated with changes in body position and upon activation elicit reflex sympathoinhibition. Here, we tested the hypothesis that postural changes modulate the sympathetically-mediated cardiac response to PEI in humans...
December 15, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/29351460/macrophage-dependent-impairment-of-%C3%AE-2-adrenergic-autoreceptor-function-in-sympathetic-neurons-from-doca-salt-but-not-high-fat-diet-induced-hypertensive-rats
#3
Ryan Kwun-Yee Mui, Roxanne Fernandes, Hannah Garver, Nico van Rooijen, James J Galligan
DOCA-salt and obesity-related hypertension are associated with inflammation and sympathetic nervous system hyperactivity. Prejunctional α2-adrenergic receptors (α2ARs) provide negative feedback to norepinephrine release from sympathetic nerves through inhibition of N-type Ca2+ channels. Increased neuronal norepinephrine release in DOCA-salt and obesity-related hypertension occurs through impaired α2AR signaling, however, the mechanisms involved are unclear. Mesenteric arteries are resistance arteries that receive sympathetic innervation from the superior mesenteric and celiac ganglia (SMCG)...
January 5, 2018: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/29351453/superoxide-inhibition-restores-endothelium-dependent-dilatation-in-aging-arteries-by-enhancing-impaired-adherens-junctions
#4
Fumin Chang, Sheila Flavahan, Nicholas A Flavahan
Endothelium-dependent, nitric oxide (NO)-mediated dilatation is impaired in aging arteries. The dysfunction reflects increased production of reactive oxygen species (ROS), is reversed by inhibiting superoxide with superoxide dismutase (SOD) mimics, and is assumed to reflect superoxide-mediated inactivation of NO. However, the dysfunction also reflects Src-dependent degradation and loss of VE-cadherin from adherens junctions, resulting in a selective impairment in the ability of the junctions to amplify endothelial dilatation...
January 12, 2018: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/29351444/activated-human-t-lymphocytes-inhibit-tgf%C3%AE-induced-fibroblast-to-myofibroblast-differentiation-via-prostaglandins-d2-and-e2
#5
Shannon H Lacy, Amali P Epa, Stephen J Pollock, Collynn F Woeller, Thomas H Thatcher, Richard P Phipps, Patricia J Sime
In pulmonary fibrosis (PF), fibroblasts and myofibroblasts proliferate and deposit excessive extracellular matrix in the interstitium, impairing normal lung function. As most forms of PF have a poor prognosis and limited treatment options, PF represents an urgent unmet need for novel, effective therapeutics. While the role of immune cells in lung fibrosis is unclear, recent studies suggest that T lymphocyte (T cell) activation may be impaired in PF patients. Further, we have previously shown that activated T cells can produce prostaglandins with anti-scarring potential...
December 20, 2017: American Journal of Physiology. Lung Cellular and Molecular Physiology
https://www.readbyqxmd.com/read/29351429/removal-of-interscapular-brown-adipose-tissue-increases-aortic-stiffness-despite-normal-systemic-glucose-metabolism-in-mice
#6
Zachary Ian Grunewald, Nathan C Winn, Michelle L Gastecki, Makenzie L Woodford, James R Ball, Sarah A Hansen, Harold S Sacks, Victoria J Vieira-Potter, Jaume Padilla
Brown adipose tissue (BAT) is considered protective against obesity and related cardiometabolic dysfunction. Indeed, activation of BAT improves glucose homeostasis and attenuates cardiovascular disease development. However, whether a reduction in BAT mass perturbs metabolic function and increases risk for cardiovascular disease remains largely unknown. To address this question, C57BL/6J male mice underwent sham or surgical bilateral excision of interscapular BAT (iBATx) and were fed a normal chow or Western diet (WD) for 18 weeks, creating four groups (n=10/group)...
December 20, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/29351420/fourth-ventricular-tsh-induces-satiety-and-increases-body-temperature-in-rats
#7
Ulrika Smedh, Karen A Scott, Timothy H Moran
Besides its well-known action to stimulate thyroid hormone release, Thyrotropin mRNA is expressed within the brain and Thyrotropin and its receptor have been shown to be present in brain areas that control feeding and gastrointestinal function. Here, the hypothesis that Thyrotropin acts on receptors in the dorsal hindbrain to alter food intake and/or gastric function was tested. Fourth ventricular injections of Thyrotropin (0.06, 0.6 and 6.0 µg) were given to rats with chronic intracerebroventricular cannulas aimed at the fourth ventricle...
January 3, 2018: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/29351410/hypoxia-selectively-upregulates-cation-channels-and-increases-cytosolic-ca2-in-pulmonary-but-not-coronary-arterial-smooth-muscle-cells
#8
Xi He, Shanshan Song, Ramon J Ayon, Angela Balisterieri, Stephen M Black, Ayako Makino, W Gil Wier, Wei-Jin Zang, Jason X-J Yuan
Ca2+ signaling, particularly the mechanism via store-operated Ca2+ entry (SOCE) and receptor-operated Ca2+ entry (ROCE), plays a critical role in the development of acute hypoxia-induced pulmonary vasoconstriction and chronic hypoxia-induced pulmonary hypertension. This study aimed to test the hypothesis that chronic hypoxia differentially regulates the expression of proteins that mediate SOCE and ROCE (STIM, Orai, and TRPC6) in pulmonary (PASMC) and coronary (CASMC) artery smooth muscle cells. The resting cytosolic [Ca2+] ([Ca2+]cyt) and the stored [Ca2+] in the sarcoplasmic reticulum (SR) were not different in CASMC and PASMC...
January 3, 2018: American Journal of Physiology. Cell Physiology
https://www.readbyqxmd.com/read/29351403/project-on-the-good-physician-further-evidence-for-the-validity-of-a-moral-intuitionist-model-of-virtuous-caring
#9
G Michael Leffel, Ross A Oakes Mueller, Sandra A Ham, Kyle E Karches, Farr A Curlin, John D Yoon
THEORY: In the Project on the Good Physician, the authors propose a moral intuitionist model of virtuous caring that places the virtues of Mindfulness, Empathic Compassion, and Generosity at the heart of medical character education. HYPOTHESES: Hypothesis 1a: The virtues of Mindfulness, Empathic Compassion, and Generosity will be positively associated with one another (convergent validity). Hypothesis 1b: The virtues of Mindfulness and Empathic Compassion will explain variance in the action-related virtue of Generosity beyond that predicted by Big Five personality traits alone (discriminant validity)...
January 19, 2018: Teaching and Learning in Medicine
https://www.readbyqxmd.com/read/29351390/vagally-mediated-gastric-effects-of-brainstem-%C3%AE-2-adrenoceptor-activation-in-stressed-rats
#10
Yanyan Jiang, Kirsteen N Browning, Luca Toti, R Alberto Travagli
Chronic stress exerts vagally-dependent effects to disrupt gastric motility; previous studies have shown that, among other nuclei, A2 neurons are involved in mediating these effects. Several studies have also shown robust in vitro and in vivo effects of α2 adrenoceptor agonists on vagal motoneurons. We have demonstrated previously that brainstem vagal neurocircuits undergo remodeling following acute stress, however, the effects following brief periods of chronic stress have not been investigated. Our aim, therefore, was to test the hypothesis that different types of chronic stress influence gastric tone and motility by inducing plasticity in the response of vagal neurocircuits to α2 adrenoreceptor agonists...
January 11, 2018: American Journal of Physiology. Gastrointestinal and Liver Physiology
https://www.readbyqxmd.com/read/29351323/fire-forbids-fifty-fifty-forest
#11
Egbert H van Nes, Arie Staal, Stijn Hantson, Milena Holmgren, Salvador Pueyo, Rafael E Bernardi, Bernardo M Flores, Chi Xu, Marten Scheffer
Recent studies have interpreted patterns of remotely sensed tree cover as evidence that forest with intermediate tree cover might be unstable in the tropics, as it will tip into either a closed forest or a more open savanna state. Here we show that across all continents the frequency of wildfires rises sharply as tree cover falls below ~40%. Using a simple empirical model, we hypothesize that the steepness of this pattern causes intermediate tree cover (30‒60%) to be unstable for a broad range of assumptions on tree growth and fire-driven mortality...
2018: PloS One
https://www.readbyqxmd.com/read/29351319/speech-stone-tool-making-and-the-evolution-of-language
#12
Dana Michelle Cataldo, Andrea Bamberg Migliano, Lucio Vinicius
The 'technological hypothesis' proposes that gestural language evolved in early hominins to enable the cultural transmission of stone tool-making skills, with speech appearing later in response to the complex lithic industries of more recent hominins. However, no flintknapping study has assessed the efficiency of speech alone (unassisted by gesture) as a tool-making transmission aid. Here we show that subjects instructed by speech alone underperform in stone tool-making experiments in comparison to subjects instructed through either gesture alone or 'full language' (gesture plus speech), and also report lower satisfaction with their received instruction...
2018: PloS One
https://www.readbyqxmd.com/read/29351198/superoxide-dismutase-mimetic-gc4419-enhances-the-oxidation-of-pharmacological-ascorbate-and-its-anticancer-effects-in-an-h%C3%A2-o%C3%A2-dependent-manner
#13
Collin D Heer, Andrew B Davis, David B Riffe, Brett A Wagner, Kelly C Falls, Bryan G Allen, Garry R Buettner, Robert A Beardsley, Dennis P Riley, Douglas R Spitz
Lung cancer, together with head and neck cancer, accounts for more than one-fourth of cancer deaths worldwide. New, non-toxic therapeutic approaches are needed. High-dose IV vitamin C (aka, pharmacological ascorbate; P-AscH-) represents a promising adjuvant to radiochemotherapy that exerts its anti-cancer effects via metal-catalyzed oxidation to form H₂O₂. Mn(III)-porphyrins possessing superoxide dismutase (SOD) mimetic activity have been shown to increase the rate of oxidation of AscH-, enhancing the anti-tumor effects of AscH- in several cancer types...
January 19, 2018: Antioxidants (Basel, Switzerland)
https://www.readbyqxmd.com/read/29351168/co-regulation-of-er-stress-and-oxidative-stress-in-neuropathic-pain-and-disinhibition-of-the-spinal-nociceptive-circuitry
#14
Yanhu Ge, Yingfu Jiao, Peiying Li, Zhenghua Xiang, Zhi Li, Long Wang, Wenqian Li, Hao Gao, Jiayun Shao, Daxiang Wen, Weifeng Yu
The accumulation of unfolded or misfolded proteins in the endoplasmic reticulum (ER) lumen leads to ER stress, which is related to cellular reactive oxygen species (ROS) production. Neuropathic pain may result from spinal dorsal horn (SDH) ER stress. In this study, we examined the cause-effect relationship between ER stress and neuropathic pain using the spinal nerve ligation(SNL) rat model. We showed that ER stress was mutually promotive with oxidative stress during the process. We also tested the hypothesis that spinal sensitization arose from reduced activities of GABA-ergic interneurons and that spinal sensitization was mediated by SDH ER stress...
January 18, 2018: Pain
https://www.readbyqxmd.com/read/29351140/does-performing-preplacement-workplace-hair-drug-testing-influence-us-department-of-transportation-random-and-postaccident-urine-drug-test-positivity-rates
#15
James W Price
BACKGROUND: Does performing pre-employment hair drug testing subsequently affect the prevalence of positive random and postaccident urine drug tests? METHODS: This cross-sectional study was designed to evaluate the prevalence of positive postaccident and random workplace urine drug tests for companies that perform pre-employment hair and urine drug testing to companies that only perform pre-employment urine drug testing. RESULTS: Fisher exact test of independence indicated no significant difference between pre-employment hair drug testing and overall US Department of Transportation random and postaccident urine drug test positivity rates...
January 18, 2018: Journal of Addiction Medicine
https://www.readbyqxmd.com/read/29351113/fatigue-failure-of-external-hexagon-connections-on-cemented-implant-supported-crowns
#16
João Malta Barbosa, Daniel Navarro da Rocha, Ronaldo Hirata, Gileade Freitas, Estevam A Bonfante, Paulo G Coelho
PURPOSE: To evaluate the probability of survival and failure modes of different external hexagon connection systems restored with anterior cement-retained single-unit crowns. The postulated null hypothesis was that there would be no differences under accelerated life testing. MATERIALS AND METHODS: Fifty-four external hexagon dental implants (∼4 mm diameter) were used for single cement-retained crown replacement and divided into 3 groups: (3i) Full OSSEOTITE, Biomet 3i (n = 18); (OL) OEX P4, Osseolife Implants (n = 18); and (IL) Unihex, Intra-Lock International (n = 18)...
January 17, 2018: Implant Dentistry
https://www.readbyqxmd.com/read/29351018/the-behavior-and-reproductive-physiology-of-a-solitary-progressive-provisioning-vespid-wasp-evidence-for-a-solitary-cycle-origin-of-reproductive-castes
#17
Hans C Kelstrup, Klaus Hartfelder, Tiago Falcon Lopes, Theresa C Wossler
The emergence of queens and workers from solitary antecedents mark a major evolutionary transition in the history of life. The solitary progressive provisioning wasp Synagris cornuta, a member of the subfamily Eumeninae (basal to eusocial vespid wasps), alternates between behavioral states characterized as queenlike and worker-like. Akin to a queen in eusocial wasps, a S. cornuta female initiates construction of a cell into which she oviposits and then, similar to a worker, cares for the brood as it develops...
February 2018: American Naturalist
https://www.readbyqxmd.com/read/29351015/temperature-dependent-growth-and-fission-rate-plasticity-drive-seasonal-and-geographic-changes-in-body-size-in-a-clonal-sea-anemone
#18
Will H Ryan
The temperature-size rule is a commonly observed pattern where adult body size is negatively correlated with developmental temperature. In part, this may occur as a consequence of allometric scaling, where changes in the ratio of surface area to mass limit oxygen diffusion as body size increases. As oxygen demand increases with temperature, a smaller body should be favored as temperature increases. For clonal animals, small changes in growth and/or fission rate can rapidly alter the average body size of clonal descendants...
February 2018: American Naturalist
https://www.readbyqxmd.com/read/29351009/life-history-traits-evolved-jointly-with-climatic-niche-and-disturbance-regime-in-the-genus-leucadendron-proteaceae
#19
Jeanne Tonnabel, Frank M Schurr, Florian Boucher, Wilfried Thuiller, Julien Renaud, Emmanuel J P Douzery, Ophélie Ronce
Organisms have evolved a diversity of life-history strategies to cope with variation in their environment. Persistence as adults and/or seeds across recruitment events allows species to dampen the effects of environmental fluctuations. The evolution of life cycles with overlapping generations should thus permit the colonization of environments with uncertain recruitment. We tested this hypothesis in Leucadendron (Proteaceae), a genus with high functional diversity native to fire-prone habitats in the South African fynbos...
February 2018: American Naturalist
https://www.readbyqxmd.com/read/29350952/fast-data-sorting-with-modified-principal-component-analysis-to-distinguish-unique-single-molecular-break-junction-trajectories
#20
J M Hamill, X T Zhao, G Mészáros, M R Bryce, M Arenz
A simple and fast analysis method to sort large data sets into groups with shared distinguishing characteristics is described and applied to single molecular break junction conductance versus electrode displacement data. The method, based on principal component analysis, successfully sorts data sets based on the projection of the data onto the first or second principal component of the correlation matrix without the need to assert any specific hypothesis about the expected features within the data. This is an improvement on the current correlation matrix analysis approach because it sorts data automatically, making it more objective and less time consuming, and our method is applicable to a wide range of multivariate data sets...
January 5, 2018: Physical Review Letters
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