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Photosynthesis Research Nov 2013This review presents an overview of the two ways that cyanobacteria, algae, and plants have adapted to high O2 and low CO2 concentrations in the environment. First, the... (Review)
Review
This review presents an overview of the two ways that cyanobacteria, algae, and plants have adapted to high O2 and low CO2 concentrations in the environment. First, the process of photorespiration enables photosynthetic organisms to recycle phosphoglycolate formed by the oxygenase reaction catalyzed by ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Second, there are a number of carbon concentrating mechanisms that increase the CO2 concentration around Rubisco which increases the carboxylase reaction enhancing CO2 fixation. This review also presents possibilities for the beneficial modification of these processes with the goal of improving future crop yields.
Topics: Adaptation, Physiological; Carbon; Carbon Dioxide; Cell Respiration; Oxygen; Photochemical Processes; Plants
PubMed: 23771683
DOI: 10.1007/s11120-013-9865-7 -
Clinical Physics and Physiological... May 1988An in-vitro circuit simulating cardiopulmonary bypass has been used to evaluate the gas transfer characteristics, gaseous microemboli production and blood damage of the...
An in-vitro circuit simulating cardiopulmonary bypass has been used to evaluate the gas transfer characteristics, gaseous microemboli production and blood damage of the Bentley-10 Plus bubble oxygenator. This oxygenator incorporates a unique integral gas controller which proportions the gas flow between the gas sparger and heat exchange area. The results of the study indicate that maintenance of a gas flow which ensures adequate CO2 removal can be prevented from inducing over-oxygenation by the manipulation of the gas controller which variably proportions the flow of gas from the oxygenation-efficient conventional gas sparger to the less efficient heat exchange area. Independent control of PaO2 with maintenance of CO2 transfer was demonstrated. Reduction in gaseous microemboli production and red blood cell damage with the use of the gas controller was demonstrated.
Topics: Blood Pressure; Carbon Dioxide; Cardiopulmonary Bypass; Equipment Design; Evaluation Studies as Topic; Hemoglobins; Humans; Oxygen; Oxygenators; Partial Pressure
PubMed: 3134153
DOI: 10.1088/0143-0815/9/2/001 -
Journal of Cellular Physiology May 2009Although O(2) concentrations are considerably lowered in vivo, depending on the tissue and cell population in question (some cells need almost anoxic environment for... (Review)
Review
Although O(2) concentrations are considerably lowered in vivo, depending on the tissue and cell population in question (some cells need almost anoxic environment for their maintenance) the cell and tissue cultures are usually performed at atmospheric O(2) concentration (20-21%). As an instructive example, the relationship between stem cells and micro-environmental/culture oxygenation has been recapitulated. The basic principle of stem cell biology, "the generation-age hypothesis," and hypoxic metabolic properties of stem cells are considered in the context of the oxygen-dependent evolution of life and its transposition to ontogenesis and development. A hypothesis relating the self-renewal with the anaerobic and hypoxic metabolic properties of stem cells and the actual O(2) availability is elaborated ("oxygen stem cell paradigm"). Many examples demonstrated that the cellular response is substantially different at atmospheric O(2) concentration when compared to lower O(2) concentrations which better approximate the physiologic situation. These lower O(2) concentrations, traditionally called "hypoxia" represent, in fact, an in situ normoxia, and should be used in experimentation to get an insight of the real cell/cytokine physiology. The revision of our knowledge on cell/cytokine physiology, which has been acquired ex vivo at non physiological atmospheric (20-21%) O(2) concentrations representing a hyperoxic state for most primate cells, has thus become imperious.
Topics: Animals; Atmosphere; Cell Differentiation; Cell Proliferation; Cell Respiration; Hypoxia; Oxygen; Stem Cells
PubMed: 19160417
DOI: 10.1002/jcp.21690 -
ASAIO Journal (American Society For... 1996One of the limitations of conventional silicone hollow fiber oxygenators compared with microporous membrane oxygenators is poor gas permeability. However, the silicone...
One of the limitations of conventional silicone hollow fiber oxygenators compared with microporous membrane oxygenators is poor gas permeability. However, the silicone hollow fiber is free from plasma leakage, which is the major life limiting factor of the microporous membrane oxygenator. It has been difficult to fabricate a fine, thin hollow fiber for reduction of resistance to gas permeability because of the poor mechanical strength of conventional silicone materials. The authors developed a novel silicone material with sufficient mechanical strength, and a fine silicone hollow fiber with a diameter of 30 microns and wall thickness of 50 microns, which is approximately half that of a conventional silicone hollow fiber. Using this newly developed silicone hollow fiber, the authors developed a compact extracapillary flow membrane oxygenator. The oxygenator consists of fine silicone hollow fibers inserted in a housing made of polycarbonate. The housing is a cylindrical case, 20 cm long and 55 mm in inside diameter. The hollow fibers are cross-wound. The surface area of the membrane is 2.0 m2, and priming volume is 230 ml. Gas transfer performance of the newly developed oxygenator was evaluated by in vitro experiments. Oxygen and carbon dioxide transfer rates were 195 ml/min and 165 ml/min, at a blood flow rate 3 L/min. The novel silicone membrane oxygenator developed in this study can be used for extended duration in such applications as extracorporeal membrane oxygenation.
Topics: Biocompatible Materials; Carbon Dioxide; Equipment Design; Evaluation Studies as Topic; Extracorporeal Membrane Oxygenation; Humans; In Vitro Techniques; Oxygen; Oxygenators, Membrane; Polymers; Resins, Synthetic; Silicones
PubMed: 8945001
DOI: 10.1097/00002480-199609000-00108 -
Revista Brasileira de Cirurgia... 2008To analyze the security and efficacy of a new membrane oxygenator, the so-called OXM - 1500.
OBJECTIVE
To analyze the security and efficacy of a new membrane oxygenator, the so-called OXM - 1500.
METHODS
From May 2005 to September 2006, six sheep of Santa InĂªs breed (five male and one female, respectively) were studied. The average body weight was 14.1 (+/-5) kg, body surface 0.6 (+/-0.2) m(2) and a mean age 3.8 (+/-1.5) months. All of them were submitted to extracorporeal circulation (CEC) with evaluation at 10, 30, 60, 120, 180 and 240 minutes. The following values were obtained: values of oxygen transference (TTO2) and carbon dioxide transference (TTCO2), haemoglobin (HBS) and free haemoglobin (HBL), the score of platelets and of leucocytes, and heat transference rate.
RESULTS
TTO2 and TTCO2 were adequate. Lesion of the majority formed blood elements was insignificant; there no modifications in HBS, HBL levels; platelets and leucocytes decreased over time. Heat exchange was effective (p < 0.05).
CONCLUSIONS
The membrane OXM--1500 infant oxygenator, tested in sheep, showed adequate oxygenation capacity, CO2 removal capacity, and small alteration of haemoglobin and platelets without significant decrease of leucocytes, as expected. Heat exchanger connected to the oxygenator was efficient in temperature changes.
Topics: Animals; Body Temperature Regulation; Carbon Dioxide; Extracorporeal Membrane Oxygenation; Female; Hemoglobins; Humans; Infant; Leukocyte Count; Male; Models, Animal; Oxygen; Oxygenators, Membrane; Platelet Count; Rewarming; Sheep
PubMed: 19082324
DOI: 10.1590/s0102-76382008000300012 -
Artificial Organs May 2004We have developed a membrane oxygenator using a novel asymmetric polyimide hollow fiber. The hollow fibers are prepared using a dry/wet phase-inversion process. The gas...
We have developed a membrane oxygenator using a novel asymmetric polyimide hollow fiber. The hollow fibers are prepared using a dry/wet phase-inversion process. The gas transfer rates of O(2) and CO(2) through the hollow fibers are investigated in gas-gas and gas-liquid systems. The polyimide hollow fiber has an asymmetric structure characterized by the presence of macrovoids, and the outer diameter of the hollow fiber is 330 microm. It is found that the polyimide hollow-fiber oxygenator can enhance the gas transfer rates of O(2) and CO(2), and that the hollow fiber provides excellent blood compatibility in vitro and in vivo.
Topics: Animals; Biocompatible Materials; Blood Gas Analysis; Carbon Dioxide; Dogs; Equipment Design; Microscopy, Electron, Scanning; Oxygen; Oxygenators, Membrane; Resins, Synthetic; Venae Cavae
PubMed: 15113344
DOI: 10.1111/j.1525-1594.2004.07257.x -
Perfusion Mar 1994Oxygen transfer performance of the Sorin Monolyth membrane oxygenator was evaluated. Similar to previous oxygen transfer performance studies conducted at this... (Comparative Study)
Comparative Study
Oxygen transfer performance of the Sorin Monolyth membrane oxygenator was evaluated. Similar to previous oxygen transfer performance studies conducted at this institution, our purpose was sixfold: (1) to construct an oxygen transfer slope (OTS); (2) to find the maximum extrapolated oxygen transfer; (3) to calculate the oxygenator performance index (OPI); (4) to generate a shunt fraction line; (5) to determine the percentage of predicted shunt (POPS); and (6) to compare the Monolyth's performance to several previously studied membrane oxygenators. From the OTS, the maximum extrapolated oxygen transfer was 346.4 ml O2/min. This absolute value was the lowest of the four oxygenators compared. When maximum oxygen transfer was compared relative to membrane surface area, the Monolyth ranked third (157.5 ml O2/min). The Monolyth produced a relatively narrow range for the OPI (81.64-130.47%) and had the lowest standard deviation (SD) in this group. The Monolyth exhibited higher shunt fractions over the range of clinical blood flows when compared to our three previously studied oxygenators. The range of POPS values (71.65-128.77%) was relatively narrow and the SD was the lowest of the four. We concluded from our evaluation that the Monolyth had relatively low top end oxygen transfer capabilities, but provided very consistent and predictable oxygen transfer performance.
Topics: Arteries; Equipment Design; Evaluation Studies as Topic; Heart-Lung Machine; Humans; Oxygen; Oxygenators, Membrane; Veins
PubMed: 7919597
DOI: 10.1177/026765919400900206 -
Current Topics in Medicinal Chemistry 2020The advancement of cardiac surgery benefits from the continual technological progress of cardiopulmonary bypass (CPB). Every improvement in the CPB technology requires... (Review)
Review
The advancement of cardiac surgery benefits from the continual technological progress of cardiopulmonary bypass (CPB). Every improvement in the CPB technology requires further clinical and laboratory tests to prove its safety and effectiveness before it can be widely used in clinical practice. In order to reduce the priming volume and eliminate a separate arterial filter in the CPB circuit, several manufacturers developed novel hollow-fiber membrane oxygenators with integrated arterial filters (IAF). Clinical and experimental studies demonstrated that an oxygenator with IAF could reduce total priming volume, blood donor exposure and gaseous microemboli delivery to the patient. It can be easily set up and managed, simplifying the CPB circuit without sacrificing safety. An oxygenator with IAF is expected to be more beneficial to the patients with low body weight and when using a minimized extracorporeal circulation system. The aim of this review manuscript was to discuss briefly the concept of integration, the current oxygenators with IAF, and the in-vitro / in-vivo performance of the oxygenators with IAF.
Topics: Cardiopulmonary Bypass; Equipment Design; Humans; Nitrogen; Oxygen; Oxygenators, Membrane
PubMed: 31820691
DOI: 10.2174/1568026619666191210161013 -
British Medical Journal Jul 1955
Topics: Cell Respiration; Humans; Nebulizers and Vaporizers; Oxygen; Respiration
PubMed: 14378666
DOI: No ID Found -
The American Journal of Physiology Jul 1957
Topics: Cell Respiration; Humans; Hypothermia; Myocardium; Oxygen; Respiration
PubMed: 13458409
DOI: 10.1152/ajplegacy.1957.190.1.57