scholarly journals Thermal sensitivity of lizard embryos indicates a mismatch between oxygen supply and demand at near‐lethal temperatures

2020 ◽  
Author(s):  
Joshua M. Hall ◽  
Daniel A. Warner
Keyword(s):  
Oxygen Supply ◽  
Thermal Sensitivity ◽  
Supply And Demand ◽  
Lethal Temperatures

scholarly journals Thermal sensitivity of lizard embryos indicates a mismatch between oxygen supply and demand at near-lethal temperatures

2019 ◽  
Author(s):  
Joshua M. Hall ◽  
Daniel A. Warner
Keyword(s):  
Heart Rate ◽  
Global Change ◽  
Embryo Development ◽  
High Temperatures ◽  
Oxygen Supply ◽  
Thermal Sensitivity ◽  
Supply And Demand ◽  
Lethal Temperature ◽  
Egg Survival ◽  
Heat Shocks

ABSTRACTAspects of global change (e.g. urbanization, climate change) result in novel, stressful thermal environments that threaten biodiversity. Though much research quantifies the thermal sensitivity of adult organisms, effects of global change on developing offspring (e.g. embryos) are also important. Oviparous, non-avian reptiles have received considerable attention because eggs are left to develop under prevailing environmental conditions, making them vulnerable to increases in ambient temperature. Though many studies assess embryo thermal tolerance and physiology in response to long-term (i.e. chronic), constant incubation temperatures, fewer assess responses to acute exposures which are more ecologically relevant for many species. We subjected eggs of the brown anole lizard (Anolis sagrei) to heat shocks, thermal ramps, and extreme diurnal fluctuations to determine the lethal temperature of embryos, measure the thermal sensitivity of embryo heart rate and metabolism, and quantify the effects of sub-lethal but stressful temperatures on embryo development and hatchling phenotypes and survival. Most embryos died at heat shocks of 45 or 46 °C, which is ∼12 °C warmer than the highest constant temperatures suitable for development. Heart rate and O2 consumption increased with temperature; however, as embryos approached the lethal temperature, heart rate and CO2 production continued rising while O2 consumption plateaued. These data indicate a mismatch between oxygen supply and demand at high temperatures. Exposure to extreme, diurnal temperature fluctuations depressed embryo developmental rates and heart rates, and resulted in hatchlings with smaller body size, reduced growth rates, and lower survival in the laboratory. Thus, even brief exposure to extreme temperatures can have important effects on embryo development, and our study highlights the role of both immediate and cumulative effects of high temperatures on egg survival. Such effects must be considered to predict how populations will respond to global change.

scholarly journals Oxygen saturations of medical inpatients in a Malawian hospital: cross-sectional study of oxygen supply and demand

Pneumonia ◽  
2012 ◽  
Vol 1 (1) ◽  
pp. 3-6 ◽  
Author(s):  
Hywel-Gethin Tudur Evans ◽  
Nadia Mahmood ◽  
Duncan G. Fullerton ◽  
Jamie Rylance ◽  
Andrew Gonani ◽  
...  
Keyword(s):  
Oxygen Supply ◽  
Supply And Demand ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Cross Sectional ◽  
Medical Inpatients

scholarly journals Applications of Oxygen-Carrying Micro/Nanobubbles: a Potential Approach to Enhance Photodynamic Therapy and Photoacoustic Imaging

2018 ◽  
Author(s):  
M. Saad Khan ◽  
Jangsun Hwang ◽  
Kyungwoo Lee ◽  
Yonghyun Choi ◽  
Kyobum Kim ◽  
...  
Keyword(s):  
Photodynamic Therapy ◽  
Oxygen Supply ◽  
Photoacoustic Imaging ◽  
Supply And Demand ◽  
Flexible Structures ◽  
Synthesis Methods ◽  
Oxygen Species ◽  
Hypoxic Conditions ◽  
Potential Use ◽  
Resistance To Chemotherapy

Microbubbles and nanobubbles can be prepared using various shells, such as phospholipids, polymers, proteins, and surfactants. They are echogenic and can be used as contrast agents for ultrasonic and photoacoustic imaging. These bubbles can be engineered in various sizes as vehicles for gas and drug delivery applications with novel properties and flexible structures. Hypoxic areas in tumors develop owing to an imbalance of oxygen supply and demand. In tumors, hypoxic regions have shown more resistance to chemotherapy, radiotherapy, and photodynamic therapies. The efficacy of photodynamic therapy depends on the availability of oxygen in the tumor to generate reactive oxygen species. Micro/nanobubbles have been shown to reverse hypoxic conditions and increase tissue oxygen levels. This review summarizes the synthesis methods and shell compositions of micro/nanobubbles and methods deployed for oxygen delivery. In addition, the shortcomings and prospects of engineering micro/nanobubbles are discussed for their potential use in photodynamic therapy.

P71 TROPONIN INCREASE AND SUBENDOCARDIAL OXYGEN SUPPLY AND DEMAND IMBALANCE IN CARDIAC AMYLOIDOSIS

2018 ◽  
Vol 24 (C) ◽  
pp. 99
Author(s):  
Lucia Salvi ◽  
Paolo Salvi ◽  
Andrea Grillo ◽  
Gianfranco Parati ◽  
Francesco Banfi ◽  
...  
Keyword(s):  
Cardiac Amyloidosis ◽  
Oxygen Supply ◽  
Supply And Demand

scholarly journals The biophysical basis of thermal tolerance in fish eggs

2020 ◽  
Vol 287 (1937) ◽  
pp. 20201550
Author(s):  
Benjamin T. Martin ◽  
Peter N. Dudley ◽  
Neosha S. Kashef ◽  
David M. Stafford ◽  
William J. Reeder ◽  
...  
Keyword(s):  
Chinook Salmon ◽  
Thermal Tolerance ◽  
Oncorhynchus Tshawytscha ◽  
Fundamental Problem ◽  
Thermal Sensitivity ◽  
Supply And Demand ◽  
Natural Habitat ◽  
Mechanistic Explanation ◽  
Biophysical Model ◽  
Warming Climate

A warming climate poses a fundamental problem for embryos that develop within eggs because their demand for oxygen (O 2 ) increases much more rapidly with temperature than their capacity for supply, which is constrained by diffusion across the egg surface. Thus, as temperatures rise, eggs may experience O 2 limitation due to an imbalance between O 2 supply and demand. Here, we formulate a mathematical model of O 2 limitation and experimentally test whether this mechanism underlies the upper thermal tolerance in large aquatic eggs. Using Chinook salmon ( Oncorhynchus tshawytscha ) as a model system, we show that the thermal tolerance of eggs varies systematically with features of the organism and environment. Importantly, this variation can be precisely predicted by the degree to which these features shift the balance between O 2 supply and demand. Equipped with this mechanistic understanding, we predict and experimentally confirm that the thermal tolerance of these embryos in their natural habitat is substantially lower than expected from laboratory experiments performed under normoxia. More broadly, our biophysical model of O 2 limitation provides a mechanistic explanation for the elevated thermal sensitivity of fish embryos relative to other life stages, global patterns in egg size and the extreme fecundity of large teleosts.

scholarly journals Predictors of cerebral blood flow in patients with and without anemia

2016 ◽  
Vol 120 (8) ◽  
pp. 976-981 ◽  
Author(s):  
Matthew T. Borzage ◽  
Adam M. Bush ◽  
Soyoung Choi ◽  
Aart J. Nederveen ◽  
Lena Václavů ◽  
...  
Keyword(s):  
Blood Flow ◽  
African American ◽  
Cerebral Blood Flow ◽  
Oxygen Content ◽  
Sickle Cell ◽  
Oxygen Supply ◽  
Complete Blood Count ◽  
Sickle Cell Trait ◽  
Supply And Demand ◽  
Cerebrovascular Reserve

Sickle cell disease (SCD) is the most common cause of stroke in childhood and results primarily from a mismatch of cerebral oxygen supply and demand rather than arterial obstruction. However, resting cerebral blood flow (CBF) has not been examined in the general African American population, in whom obesity, hypertension, cerebrovascular disease, and diminished cerebrovascular reserve capacity are common. To better understand the underlying physiological substrate upon which SCD is superimposed, we measured CBF in 32 young (age 28 ± 10 yr), asymptomatic African American subjects with and without sickle cell trait ( n = 14). To characterize the effects of chronic anemia, in isolation of sickle hemoglobin we also studied a cohort of 13 subjects with thalassemia major ( n = 10), dyserythropoetic anemia ( n = 1), or spherocytosis ( n = 2). Blood was analyzed for complete blood count, hemoglobin electrophoresis, cell free hemoglobin, and lactate dehydrogenase. Multivariate regression analysis showed that oxygen content was the strongest predictor of CBF ( r2 = 0.33, P < 0.001). CBF declined rapidly in the second and third decades of life, but this drop was explained by reductions in cerebral gray matter. However, age effects persisted after correction for brain composition, possibly representing microvascular impairment. CBF was independent of viscosity, hemoglobin S%, and body mass index. Hyperoxia resulted in reduced CBF by 12.6% ( P = 0.0002), and CBF changes were proportional to baseline oxygen content ( r2 = 0.16, P = 0.02). These data suggest that these hemoglobin subtypes do not alter the normal CBF regulation of the balance of oxygen supply and demand.

High-resolution visualization of oxygen distribution in the liver in vivo

2004 ◽  
Vol 286 (1) ◽  
pp. G37-G44 ◽  
Author(s):  
Markus Paxian ◽  
Steve A. Keller ◽  
Brian Cross ◽  
Toan T. Huynh ◽  
Mark G. Clemens
Keyword(s):  
Redox State ◽  
Oxygen Supply ◽  
Supply And Demand ◽  
Hepatic Tissue ◽  
Oxygen Distribution ◽  
Sprague Dawley ◽  
Additional Information ◽  
Nadh Fluorescence ◽  
Oxygen Sensitive

Microcirculatory failure after stress events results in mismatch in oxygen supply and demand. Determination of tissue oxygen distribution in vivo may help elucidate mechanisms of injury, but present methods have limited resolution. Male Sprague-Dawley rats were anesthetized, prepared for intravital microscopy, and received intravenously the oxygen-sensitive fluorescent dye Tris(1,10-phenanthroline)ruthenium(II) chloride hydrate [[Formula: see text]]. An impaired hepatic oxygen distribution was induced by either phenylephrine or hemorrhage. Intensity of [Formula: see text] fluorescence was compared with NADH autofluorescence indicating changes in the mitochondrial redox potential. Ethanol was injected to affect the NADH-to-NAD+ ratio without altering the Po2. Infusion of [Formula: see text] resulted in a heterogeneous fluorescence under baseline conditions reflecting the physiological acinar Po2 distribution. A decrease in oxygen supply due to phenylephrine or hemorrhage was paralleled by an increase in [Formula: see text] and NADH fluorescence reflecting an impaired mitochondrial redox state. Ethanol did not alter [Formula: see text] fluorescence but increased NADH fluorescence indicating independence of Po2 and redox state imaging. Intravenous administration of [Formula: see text] for intravital videomicroscopy represents a new method to visualize the hepatic tissue Po2. Combined with NADH autofluorescence, it provides additional information regarding the tissue redox state.

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