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 Effects of Esmolol on Vascular Waterfall Phenomenon in Septic Shock Patients by Bedside Measurement of Critical Closure Pressure and Mean Systemic Filling Pressure: A Prospective Observational Study

2021 ◽  
Author(s):  
Zehan Liu ◽  
Chuanliang Pan ◽  
Jianping Liu ◽  
Hui Liu ◽  
Hui Xie
Keyword(s):  
Heart Rate ◽  
Septic Shock ◽  
Rate Control ◽  
Oxygen Supply ◽  
Supply And Demand ◽  
Filling Pressure ◽  
The Body ◽  
Heart Rate Control ◽  
Hemodynamic Optimization ◽  
The Difference

Abstract Background To explore the effect of esmolol on the vascular waterfall phenomenon and body oxygen supply and demand in septic shock patients by bedside measurements of critical closure pressure (Pcc) and mean systemic circulation filling pressure (Pmsf). Methods Enrolled in the Intensive Care Medicine Unit (ICU) of the Third People's Hospital of Chengdu City/Southwest Jiaotong University Hospital from August 2019 to January 2021, admitted to our department for infectious shock. Adults with endotracheal intubation, invasive ventilator-assisted ventilation, pulse-indicated continuous cardiac output monitoring (PiCCO) catheters and deep venous catheters placed for medical reasons. Results After 24 hours of initial hemodynamic optimization, 56 patients were finally enrolled. After heart rate control with esmolol, patients had a significant decrease in cardiac index (CI) (4.0 vs. 3.3 L/min/m2, p < 0.001), a significant increase in stroke index (SI) (34.1 vs. 36.6 ml/m2, p < 0.01), and a significant decrease in heart rate (HR) (116.8 vs. 90.6 beats/min, p < 0.001). After 1 hour of treatment with esmolol, patients had a significant increase in Pcc (31.4 vs 36.7 mmHg, p < 0.01). The difference between Pcc and Pmsf before and after treatment was statistically different (4.0 vs 10.0 mmHg, p < 0.01). After heart rate control with esmolol, the patients had a significant increase in the body circulation vascular resistance indices (RIs) (15.14 vs 18.25 mmHg/min/m2-L-1, p < 0.001). There was an increase in ScvO2 in patients after treatment with esmolol, but the difference was not statistically significant (68.4% vs 69.8%, p > 0.05), while Pcv-aCO2 was significantly lower (6.3 vs 4.9 mmHg, p < 0.001) and patients had a significant decrease in blood lactate levels (4.0 vs 3.6 mmol/L, p < 0.05) . Conclusion Patients with septic shock whose heart rate was still greater than 95 beats/min after hemodynamic optimization were treated with esmolol, which could effectively control heart rate and reduce CI, as well as improve Pcc and increase the difference between Pcc and Pmsf, without affecting MAP, CVP, Pmsf and arteriovenous vascular resistance, and improve the balance of oxygen supply and demand in the body.

scholarly journals Esmolol response in septic shock patients in relation to vascular waterfall phenomenon measured by critical closure pressure and mean systemic filling pressure: a prospective observational study

2022 ◽  
Vol 10 (1) ◽  
Author(s):  
Zehan Liu ◽  
Chuanliang Pan ◽  
Jianping Liu ◽  
Hui Liu ◽  
Hui Xie
Keyword(s):  
Heart Rate ◽  
Septic Shock ◽  
Vascular Resistance ◽  
Oxygen Supply ◽  
Supply And Demand ◽  
Filling Pressure ◽  
The Body ◽  
Controlled Study ◽  
Hemodynamic Optimization ◽  
The Difference

Abstract Background Bedside measurements of critical closure pressure (Pcc) and mean systemic circulation filling pressure (Pmsf) were utilized to evaluate the response to esmolol in septic shock patients, in relation to the vascular waterfall phenomenon and body oxygen supply and demand. Methods This prospective observational self-controlled study included patients with septic shock, newly admitted to the intensive care unit, between August 2019 and January 2021. Pcc and Pmsf, along with the heart rate and other hemodynamic indicators were observed and compared before and 1 h after esmolol IV infusion. Results After 24 h of initial hemodynamic optimization, 56 patients were finally enrolled. After start of esmolol infusion, patients had a significant decrease in cardiac index (CI) (4.0 vs. 3.3 L/min/m2, P < 0.001), a significant increase in stroke index (SI) (34.1 vs. 36.6 mL/m2, P < 0.01), and a significant decrease in heart rate (HR) (116.8 vs. 90.6 beats/min, P < 0.001). After 1 h of treatment with esmolol, patients had a significant increase in Pcc (31.4 vs. 36.7 mmHg, P < 0.01). The difference between Pcc and Pmsf before and after treatment was statistically different (4.0 vs. 10.0 mmHg, P < 0.01). After heart rate control with esmolol, the patients had a significant increase in the body circulation vascular resistance indices (RIs) (15.14 vs. 18.25 mmHg/min/m2/L, P < 0.001). There was an increase in ScvO2 in patients after treatment with esmolol, but the difference was not statistically significant (68.4% vs. 69.8%, P > 0.05), while Pcv-aCO2 was significantly lower (6.3 vs. 4.9 mmHg, P < 0.001) and patients had a significant decrease in blood lactate levels (4.0 vs. 3.6 mmol/L, P < 0.05). Conclusion Patients with septic shock whose heart rate is greater than 95 beats/min after hemodynamic optimization were treated with esmolol, which could effectively control heart rate and reduce CI, as well as improve Pcc and increase the difference between Pcc and Pmsf (known as “vascular waterfall” phenomenon), without affecting MAP, CVP, Pmsf and arteriovenous vascular resistance, and improve the balance of oxygen supply and demand in the body.

scholarly journals TEMPERATURE AND HEART RATE IN PTEROTRACHEA AND TIEDEMANNIA

1925 ◽  
Vol 9 (2) ◽  
pp. 269-284 ◽  
Author(s):  
Otto Glaser
Keyword(s):  
Heart Rate ◽  
High Temperatures ◽  
Synthetic Process ◽  
Average Value ◽  
Oxidative Reactions ◽  
Limax Maximus ◽  
The One ◽  
Lower Limits ◽  
Co2 Excretion ◽  
Do So

1. For the heart rate in Pterotrachea coronata, intermediate temperatures disclose a thermal increment of 11,200 ±. This value is identical with the one reported by Crozier and Stier for the lamelli-branch, Anodonta. In the pteropod, Tiedemannia neapolitana the same temperatures typically reveal in the heart rate a µ value of 16,200 ± This agrees quantitatively with 16,300 found by Crozier and Stier for the heart of the slug, Limax maximus. 2. At high temperatures the average value of µ for Pterotrachea is 7,300: for Tiedemannia, 7,400. The corresponding averages at the lower limits are 22,000 and 23,000. 3. The great variability found near the edges of the temperature field are explicable in two ways. During intermissions characteristic of high temperatures and occurring also at low, we can assume a restorative process; while at both the upper and lower limits we may, in addition, find that reactions assume control which under ordinary circumstances never do so. Special evidence indicates that the highest temperatures employed, 27°C., and the lowest, 4°C., caused no irreversible changes in mechanism. 4. The theoretical analysis of the experimental facts makes use of Meyerhof's conception of carbohydrate metabolism and projects the cyclical nature of rhythm into the substrate of control. Assuming as a source of energy an original supply of material O, the value of 22,000 ± is assigned provisionally to a mobilization hydrolysis while 11,200 ± and 16,000 ± are attached to oxidative reactions influenced respectively by OH' and possibly Fe, or some other catalyst. The lowest value, 7,300 ± is assumed to indicate a synthetic process (lactic acid → glycogen?), possibly limited by CO2 excretion. In the present state of our knowledge, this distribution and interpretation seems to account reasonably for the experimental facts, but until we know more about the neurogenic controls, is entitled to rank only as an hypothesis.

SOME LETHAL TEMPERATURE RELATIONS OF TWO MINNOWS OF THE GENUS CHROSOMUS

1966 ◽  
Vol 44 (3) ◽  
pp. 349-364 ◽  
Author(s):  
Albert V. Tyler
Keyword(s):  
Thermal Shock ◽  
High Temperatures ◽  
The Other ◽  
Lethal Temperature ◽  
Lethal Temperatures ◽  
Equal Temperature

The resistance and tolerance of Chrosomus eos and Chrosomus neogaeus to high temperatures were examined. Tests were conducted with C. neogaeus in winter and with C. eos in winter and summer. For both species, death at high temperatures could be separated into three lethal patterns or "effects". The first effect seemed to be associated, at least in part, with thermal shock. Factors generating the other effects were not apparent.Both species showed about the same degree of tolerance and resistance to high temperatures when they were acclimated to 15 °C or higher. At 9 °C, C. eos was less tolerant to high lethal temperatures than was C. neogaeus.When equal temperature acclimations were compared, C. eos was more resistant to high lethal temperatures in summer than in winter.

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 Increased Thermal Sensitivity of a Tropical Marine Gastropod Under Combined CO2 and Temperature Stress

2021 ◽  
Vol 8 ◽  
Author(s):  
Jay J. Minuti ◽  
Charlee A. Corra ◽  
Brian S. Helmuth ◽  
Bayden D. Russell
Keyword(s):  
Defense Mechanism ◽  
Thermal Sensitivity ◽  
Interactive Effects ◽  
Lethal Temperature ◽  
Weather Extremes ◽  
Short Term ◽  
Metabolic Plasticity ◽  
The Face ◽  
Metabolic Performance ◽  
Maximum Metabolic Rate

The ability of an organism to alter its physiology in response to environmental conditions offers a short-term defense mechanism in the face of weather extremes resulting from climate change. These often manifest as multiple, interacting drivers, especially pH and temperature. In particular, decreased pH can impose constraints on the biological mechanisms which define thermal limits by throwing off energetic equilibrium and diminishing physiological functions (e.g., in many marine ectotherms). For many species, however, we do not have a detailed understanding of these interactive effects, especially on short-term acclimation responses. Here, we investigated the metabolic plasticity of a tropical subtidal gastropod (Trochus maculatus) to increased levels of CO2 (700 ppm) and heating (+3°C), measuring metabolic performance (Q10 coefficient) and thermal sensitivity [temperature of maximum metabolic rate (TMMR), and upper lethal temperature (ULT)]. Individuals demonstrated metabolic acclimation in response to the stressors, with TMMR increasing by +4.1°C under higher temperatures, +2.7°C under elevated CO2, and +4.4°C under the combined stressors. In contrast, the ULT only increased marginally in response to heating (+0.3°C), but decreased by −2.3°C under CO2, and −8.7°C under combined stressors. Therefore, although phenotypic plasticity is evident with metabolic acclimation, acute lethal temperature limits seem to be less flexible during short-term acclimation.

scholarly journals Impact of anthropogenic ocean acidification on thermal tolerance of the spider crab <i>Hyas araneus</i>

2009 ◽  
Vol 6 (2) ◽  
pp. 2837-2861 ◽  
Author(s):  
K. Walther ◽  
F. J. Sartoris ◽  
C. Bock ◽  
H. O. Pörtner
Keyword(s):  
Heart Rate ◽  
Thermal Tolerance ◽  
Thermal Sensitivity ◽  
Co2 Concentration ◽  
Spider Crab ◽  
Thermal Window ◽  
Co2 Levels ◽  
Hyas Araneus ◽  
Q10 Values ◽  
Critical Temperature Tc

Abstract. Future scenarios project combined developments of elevated CO2 concentrations and global warming and their impact on marine ecosystems. The synergistic impact of both factors was addressed by studying the effect of CO2 accumulation on thermal tolerance of the cold-eurythermal spider crab Hyas araneus. Animals were exposed to present day normocapnia (380 ppm CO2), CO2 levels expected towards 2100 (710 ppm) and beyond (3000 ppm). Heart rate and haemolymph PO2 (PeO2) were measured during progressive short term cooling from 10 to 0°C and during warming from 10 to 25°C. An increase of PeO2 occurred during cooling with highest values reached at 0°C under all three CO2 levels. Heart rate increased during warming until a critical temperature (Tc) was reached. The putative Tc under normocapnia was presumably >25°C, from where it fell to 23.5°C under 710 ppm and then 21.1°C under 3000 ppm. At the same time, thermal sensitivity, as seen in the Q10 values of heart rate, rose with increasing CO2 concentration in the warmth. Our results suggest a narrowing of the thermal window of Hyas araneus under moderate increases in CO2 levels by exacerbation of the heat or cold induced oxygen and capacity limitation of thermal tolerance.

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.

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