183 research outputs found
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Forest Response to Chronic Hurricane Disturbance in Coastal New England
Question: Hurricanes and cyclones cause a wide range of damage to coastal forests worldwide. Most of these storms are not catastrophic in ecological terms, but forest responses to storms of moderate intensities are poorly understood. In regions with a high frequency of moderate hurricanes, how does variation in disturbance intensity affect the magnitude of ecological responses?
Location: Naushon Island, Massachusetts USA
Methods: We use historical records and dendroecological methods to characterize establishment and growth of Fagus grandifolia, Quercus alba and Quercus velutina in response to seven non-catastrophic hurricanes of varying intensity and a major logging event, relative to baseline conditions, over the past ~ 150 years. Our aim was to document variation in the magnitude of responses to known disturbance events of varying intensity, and to determine whether tree growth after moderate hurricanes differs from growth during periods of no disturbance.
Results: Forest harvesting in 1824-1827 had a strong impact on forest composition and growth. Since then, the study region has been characterized by little harvesting but frequent hurricanes. However, only one of the seven storms examined caused substantial increases in growth and new establishment for the dominant species; most moderate disturbances had minimal impacts on growth and regeneration dynamics. We also document highly variable responses among species to individual storms, including substantial growth decreases that may not be detected by standard analytical approaches.
Conclusions: Our results caution against the use of simple metrics such as wind speed to predict forest response to specific hurricanes, and highlight the importance of individual disturbance events in controlling long-term forest dynamics, even in regions characterized by high disturbance frequency. Additionally, we show that standard approaches to reconstructing disturbance history based on increases in radial growth and pulses of tree establishment are likely to underestimate the frequency of moderate disturbances.Other Research Uni
Changes in cerebral vascular reactivity and structure following prolonged exposure to high altitude in humans.
Although high-altitude exposure can lead to neurocognitive impairment, even upon return to sea level, it remains unclear the extent to which brain volume and regional cerebral vascular reactivity (CVR) are altered following high-altitude exposure. The purpose of this study was to simultaneously determine the effect of 3 weeks at 5050 m on: (1) structural brain alterations; and (2) regional CVR after returning to sea level for 1 week. Healthy human volunteers (n = 6) underwent baseline and follow-up structural and functional magnetic resonance imaging (MRI) at rest and during a CVR protocol (end-tidal PCO2 reduced by -10, -5 and increased by +5, +10, and +15 mmHg from baseline). CVR maps (% mmHg(-1)) were generated using BOLD MRI and brain volumes were estimated. Following return to sea level, whole-brain volume and gray matter volume was reduced by 0.4 ± 0.3% (P < 0.01) and 2.6 ± 1.0% (P < 0.001), respectively; white matter was unchanged. Global gray matter CVR and white matter CVR were unchanged following return to sea level, but CVR was selectively increased (P < 0.05) in the brainstem (+30 ± 12%), hippocampus (+12 ± 3%), and thalamus (+10 ± 3%). These changes were the result of improvement and/or reversal of negative CVR to positive CVR in these regions. Three weeks of high-altitude exposure is reflected in loss of gray matter volume and improvements in negative CVR
Changes in cerebral vascular reactivity and structure following prolonged exposure to high altitude in humans
Critical comments on the WHO-UNEP State of the Science of Endocrine Disrupting Chemicals – 2012
AbstractEarly in 2013, the World Health Organization (WHO) released a 2012 update to the 2002 State of the Science of Endocrine Disrupting Chemicals. Several significant concerns have been identified that raise questions about conclusions reached in this report regarding endocrine disruption. First, the report is not a state-of-the-science review and does not follow the 2002 WHO recommended weight-of-evidence approach. Second, endocrine disruption is often presumed to occur based on exposure or a potential mechanism despite a lack of evidence to show that chemicals are causally established as endocrine disruptors. Additionally, causation is often inferred by the presentation of a series of unrelated facts, which collectively do not demonstrate causation. Third, trends in disease incidence or prevalence are discussed without regard to known causes or risk factors; endocrine disruption is implicated as the reason for such trends in the absence of evidence. Fourth, dose and potency are ignored for most chemicals discussed. Finally, controversial topics (i.e., low dose effects, non-monotonic dose response) are presented in a one-sided manner and these topics are important to understanding endocrine disruption. Overall, the 2012 report does not provide a balanced perspective, nor does it accurately reflect the state of the science on endocrine disruption
The Vehicle, Spring 2008
Table of Contents
Not So Hot Cocoa (To a fish named Mooshu)Gina Lobiancopage 1
LessonsGlen Davispage 2
Christian Campus HouseJacob Fosterpage 4
Gray AreaRebecca Griffithpage 5
Gathering RosebudsJacob Fosterpage 6
Play Those BluesJacob Dawsonpage 8
The Apple CarAmanda Vealepage 10
A Night at the UptownerJacob Fosterpage 12
Candy DishAnthony Hesseldenzpage 14
Winter DayAnna-Elise Pricepage 15
The Friendly FogSarah Ruhollpage 16
Hey MamaJacob Dawsonpage 18
Keep TurningStephanie Drozdpage 20
A Pen, A Rose, and a Bottle of JackCarissa Haydenpage 21
Ten Days LaterAndrew Deckerpage 22
FearShannara Holderpage 27
Thank You and GoodnightJacob Fosterpage 28
My Mother\u27s PassingAmanda Vealepage 30
The Bearded ManAndrew Deckerpage 32
TabooMario Podeschipage 34
DervishScott Lutzpage 41
IckJacob Fosterpage 42
Meditation of the SeasonsStephanie Drozdpage 45
Full MoonAnna-Elise Pricepage 47
Becoming WiseAmanda Vealepage 48
In SightAnthony Hesseldenzpage 50
About the Authors
Art Submissions
Down the TracksShannara Holdercovers and page 23
Out the Back DoorShannara Holderpage 24
UntitledJennifer O\u27Neilpage 25
LullabyShannara Holderpage 26https://thekeep.eiu.edu/vehicle/1089/thumbnail.jp
The G Protein Biased Small Molecule Apelin Agonist CMF-019 is Disease Modifying in Endothelial Cell Apoptosis In Vitro and Induces Vasodilatation Without Desensitisation In Vivo
Signaling through the apelin receptor is beneficial for a number of diseases including pulmonary arterial hypertension. The endogenous small peptides, apelin and elabela/toddler, are downregulated in pulmonary arterial hypertension but are not suitable for exogenous administration owing to a lack of bioavailability, proteolytic instability and susceptibility to renal clearance. CMF-019, a small molecule apelin agonist that displays strong bias towards G protein signaling over β-arrestin (∼400 fold), may be more suitable. This study demonstrates that in addition to being a positive inotrope, CMF-019 caused dose-dependent vasodilatation in vivo (50 nmol 4.16 ± 1.18 mmHg, **p < 0.01; 500 nmol 6.62 ± 1.85 mmHg, **p < 0.01), without receptor desensitization. Furthermore, CMF-019 rescues human pulmonary artery endothelial cells from apoptosis induced by tumor necrosis factor α and cycloheximide (5.66 ± 0.97%, **p < 0.01) by approximately 50% of that observable with rhVEGF (11.59 ± 1.85%, **p < 0.01), suggesting it has disease-modifying potential in vitro. CMF-019 displays remarkable bias at the apelin receptor for a small molecule and importantly recapitulates all aspects of the cardiovascular responses to the endogenous ligand, [Pyr1]apelin-13, in vivo. Additionally, it is able to protect human pulmonary artery endothelial cells from apoptosis, suggesting that the beneficial effects observed with apelin agonists extend beyond hemodynamic alleviation and address disease etiology itself. These findings support CMF-019 as a G protein biased small molecule apelin agonist in vitro and in vivo that could form the basis for the design of novel therapeutic agents in chronic diseases, such as, pulmonary arterial hypertension
Recommended from our members
The G Protein Biased Small Molecule Apelin Agonist CMF-019 is Disease Modifying in Endothelial Cell Apoptosis In Vitro and Induces Vasodilatation Without Desensitisation In Vivo
Signaling through the apelin receptor is beneficial for a number of diseases including pulmonary arterial hypertension. The endogenous small peptides, apelin and elabela/toddler, are downregulated in pulmonary arterial hypertension but are not suitable for exogenous administration owing to a lack of bioavailability, proteolytic instability and susceptibility to renal clearance. CMF-019, a small molecule apelin agonist that displays strong bias towards G protein signaling over β-arrestin (∼400 fold), may be more suitable. This study demonstrates that in addition to being a positive inotrope, CMF-019 caused dose-dependent vasodilatation in vivo (50 nmol 4.16 ± 1.18 mmHg, **p < 0.01; 500 nmol 6.62 ± 1.85 mmHg, **p < 0.01), without receptor desensitization. Furthermore, CMF-019 rescues human pulmonary artery endothelial cells from apoptosis induced by tumor necrosis factor α and cycloheximide (5.66 ± 0.97%, **p < 0.01) by approximately 50% of that observable with rhVEGF (11.59 ± 1.85%, **p < 0.01), suggesting it has disease-modifying potential in vitro. CMF-019 displays remarkable bias at the apelin receptor for a small molecule and importantly recapitulates all aspects of the cardiovascular responses to the endogenous ligand, [Pyr1]apelin-13, in vivo. Additionally, it is able to protect human pulmonary artery endothelial cells from apoptosis, suggesting that the beneficial effects observed with apelin agonists extend beyond hemodynamic alleviation and address disease etiology itself. These findings support CMF-019 as a G protein biased small molecule apelin agonist in vitro and in vivo that could form the basis for the design of novel therapeutic agents in chronic diseases, such as, pulmonary arterial hypertension
Reduced blood flow through intrapulmonary arteriovenous anastomoses at rest and during exercise in lowlanders during acclimatization to high altitude
Blood flow through intrapulmonary arteriovenous anastomoses (QIPAVA ) is elevated during exercise at sea level (SL) and at rest in acute normobaric hypoxia. Following high altitude (HA) acclimatization, resting QIPAVA is similar to SL, but it is unknown if this is true during exercise at HA. We reasoned that exercise at HA (5,050 m) would exacerbate QIPAVA due to heightened pulmonary arterial pressure. Using a supine cycle ergometer, seven healthy adults free from intracardiac shunts underwent an incremental exercise test at SL (25, 50, 75% of SL VO2peak ) and at HA (25, 50% of SL VO2peak ). Echocardiography was used to determine cardiac output (Q) and pulmonary artery systolic pressure (PASP) and agitated saline contrast was used to determine QIPAVA (bubble score; 0-5). The principal findings were: (1) Q was similar at SL-rest (3.9 +/- 0.47 l min-1 ) compared with HA-rest (4.5 +/- 0.49 l min-1 ; P = 0.382), but increased from rest during both SL and HA exercise (P < 0.001); (2) PASP increased from SL-rest (19.2 +/- 0.7 mmHg) to HA-rest (33.7 +/- 2.8 mmHg; P = 0.001) and, compared with SL, PASP was further elevated during HA exercise (P = 0.003); (3) QIPAVA was increased from SL-rest (0) to HA-rest (median = 1; P = 0.04) and increased from resting values during SL exercise (P < 0.05), but were unchanged during HA exercise (P = 0.91), despite significant increases in Q and PASP. Theoretical modeling of microbubble dissolution suggests that the lack of QIPAVA in response to exercise at HA is unlikely caused by saline contrast instability
Chemoreceptor responsiveness at sea level does not predict the pulmonary pressure response to high altitude
The hypoxic ventilatory response (HVR) at sea level (SL) is moderately predictive of the
change in pulmonary artery systolic pressure (PASP) to acute normobaric hypoxia. However, because of
progressive changes in the chemoreflex control of breathing and acid-base balance at high altitude (HA),
HVR at SL may not predict PASP at HA. We hypothesized that resting peripheral oxyhemoglobin
saturation (SpO2) at HA would correlate better than HVR at SL to PASP at HA. In 20 participants at SL,
we measured normobaric, isocapnic HVR (L/min·-%SpO2
-1) and resting PASP using echocardiography.
Both resting SpO2 and PASP measures were repeated on day 2 (n=10), days 4-8 (n=12), and 2-3 weeks
(n=8) after arrival at 5050m. These data were also collected at 5050m on life-long HA residents (Sherpa;
n=21). Compared to SL, SpO2 decreased from 98.6 to 80.5% (P<0.001), while PASP increased from
21.7 to 34.0mmHg (P<0.001) after 2-3 weeks at 5050m. Isocapnic HVR at SL was not related to SpO2
or PASP at any time point at 5050m (all P>0.05). Sherpa had lower PASP (P<0.01) than lowlanders on
days 4-8 despite similar SpO2. Upon correction for hematocrit, Sherpa PASP was not different from
lowlanders at SL, but lower than lowlanders at all HA time points. At 5050m, whilst SpO2 was not
related to PASP in lowlanders at any point (all R2=0.50), there was a weak relationship in the
Sherpa (R2=0.16; P=0.07). We conclude that neither HVR at SL nor resting SpO2 at HA correlates with
elevations in PASP at HA
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