Search results for "RESPIRATION"
showing 10 items of 538 documents
Respiratory support techniques to avoid desaturation in critically ill patients requiring endotracheal intubation: A systematic review and meta-analy…
2017
Abstract Purpose To evaluate which respiratory support method for critically ill patients undergoing endotracheal intubation (ETI) is associated with less desaturation. Methods We searched PubMed, Cochrane Library, Scopus and CINAHL databases. We included randomized (RCT) and non-randomized (non-RCT) studies investigating any method of respiratory support before/during ETI compared to a reference control. Results Apneic oxygenation (ApOx) was the most commonly investigated respiratory support technique for critically ill patients undergoing intubation (4 RCTs, 358 patients). Three of these studies investigated high-flow nasal cannula (HFNC) for ApOx while standard nasal cannula was used in …
Neuronal Bioenergetics and Acute Mitochondrial Dysfunction: A Clue to Understanding the Central Nervous System Side Effects of Efavirenz
2014
Background. Neurological pathogenesis is associated with mitochondrial dysfunction and differences in neuronal/glial handling of oxygen and glucose. The main side effects attributed to efavirenz involve the CNS, but the underlying mechanisms are unclear. Methods. Human cell lines and rat primary cultures of neurons and astrocytes were treated with clinically relevant efavirenz concentration. Results. Efavirenz alters mitochondrial respiration, enhances reactive oxygen species generation, undermines mitochondrial membrane potential, and reduces adenosine triphosphate (ATP) levels in a concentration-dependent fashion in both neurons and glial cells. However, it activates adenosine monophospha…
Evidence for the operation of a cyanide-sensitive oxidase in chlororespiration in the thylakoids of the chlorophyll c-containing alga Pleurochloris m…
1995
For characterisation of chlororespiration in the chlorophyll c-containing alga Pleurochloris meiringensis, we measured the flash-induced electrochromic absorbance changes between 470 and 545 nm and the redox changes of cytochrome f and cytochrome c553. Cytochrome c553 was shown to be present in high amounts (1 mol cytochrome c553 per 300 mol chlorophyll) in this alga and to function as the obligate electron donor for photosystem I instead of plastocyanin. Whereas salicylhydroxamic acid had no effect on the flash-induced absorbance transients, cyanide enhanced the slow-rising (t1/2≈10 ms) kinetic component of the electrochromic absorbance change. Cyanide also accelerated the re-reduction of …
Psychrotolerant Sulfate-reducing Bacteria from an Oxic Freshwater Sediment Description of Desulfovibrio cuneatus sp. nov. and Desulfovibrio litoralis…
1998
The most abundant culturable sulfate-reducing bacteria were isolated from the littoral sediment of the oligotrophic Lake Stechlin. The strains STL1 and STL4 were obtained from the oxic uppermost layer, while strain STL6 was isolated from the anoxic zone in 20 to 30 mm depth. The isolates showed a striking morphological feature in tapering off at one end of the cell. Physiological characteristics related them to the genus Desulfovibrio. They contained desulfoviridin. H2, formate, pyruvate, lactate, and fumarate were utilized with sulfate, sulfite, thiosulfate, or elemental sulfur as electron acceptors. All isolates were able to reduce oxygen and survived 120 h of aeration. However, aerobic g…
A respiratory hemocyanin from an insect.
2004
Insects possess an elaborate tracheal system that enables transport of gaseous oxygen from the atmosphere directly to the inner organs. Therefore, the presence of specialized oxygen-transport proteins in the circulatory system of insects has been considered generally unnecessary. Here, we show for the first time, to our knowledge, the presence of an ancestral and functional hemocyanin (Hc) in an insect. In the hemolymph of nymphs and adults of the stonefly Perla marginata , a hexameric Hc was identified, which consists of two distinct subunit types of 659 and 655 amino acids. P. marginata Hc displays cooperative oxygen binding with a moderately high oxygen affinity [(half-saturation pressu…
Integrating Decomposers, Methane-Cycling Microbes and Ecosystem Carbon Fluxes Along a Peatland Successional Gradient in a Land Uplift Region
2021
AbstractPeatlands are carbon dioxide (CO2) sinks that, in parallel, release methane (CH4). The peatland carbon (C) balance depends on the interplay of decomposer and CH4-cycling microbes, vegetation, and environmental conditions. These interactions are susceptible to the changes that occur along a successional gradient from vascular plant-dominated systems to Sphagnum moss-dominated systems. Changes similar to this succession are predicted to occur from climate change. Here, we investigated how microbial and plant communities are interlinked with each other and with ecosystem C cycling along a successional gradient on a boreal land uplift coast. The gradient ranged from shoreline to meadows…
The ABCflux database: Arctic-Boreal CO<sub>2</sub> flux observations and ancillary information aggregated to monthly time…
2021
Abstract. Past efforts to synthesize and quantify the magnitude and change in carbon dioxide (CO2) fluxes in terrestrial ecosystems across the rapidly warming Arctic-Boreal Zone (ABZ) have provided valuable information, but were limited in their geographical and temporal coverage. Furthermore, these efforts have been based on data aggregated over varying time periods, often with only minimal site ancillary data, thus limiting their potential to be used in large-scale carbon budget assessments. To bridge these gaps, we developed a standardized monthly database of Arctic-Boreal CO2 fluxes (ABCflux) that aggregates in-situ measurements of terrestrial net ecosystem CO2 exchange and its derived …
Changes in the proton potential and the cellular energetics of Escherichia coli during growth by aerobic and anaerobic respiration or by fermentation.
1998
The energetic parameters of Escherichia coli were analyzed for the aerobic/anaerobic transition. The electrochemical proton potential (delta p) across the cytoplasmic membrane was determined in the steady state of respiration with O2, nitrate, fumarate, dimethylsulfoxide (Me2SO), and for fermentation. With O2, a proton potential of -160 mV was obtained. For anaerobic respiration with nitrate, fumarate or Me2SO, delta p decreased only slightly by about 20 mV in contrast to earlier assumptions, whereas delta p dropped by approximately 40 mV during fermentation. Under all conditions, the membrane potential (delta psi) contributed the major portion to delta p. The cellular ATP levels were highe…
Novel technologies to detect atelectotrauma in the injured lung
2010
ABSTRACTCyclical recruitment and derecruitment of lung parenchyma (R/D) remains a serious problem in ALI/ARDS patients, defined as atelectotrauma. Detection of cyclical R/D to titrate the optimal respiratory settings is of high clinical importance. Image-based technologies that are capable of detecting changes of lung ventilation within a respiratory cycle include dynamic computed tomography (dCT), synchrotron radiation computed tomography (SRCT), and electrical impedance tomography (EIT). Time-dependent intra-arterial oxygen tension monitoring represents an alternative approach to detect cyclical R/D, as cyclical R/D can result in oscillations of PaO2 within a respiratory cycle. Continuous…
Objective, Noninvasive Evaluation of Velopharyngeal Function in Cleft and Noncleft Patients
1998
Objective The purpose of this study was to investigate a new diagnostic method that provides an approach to noninvasive, objective measurement of velopharyngeal movement by acoustic determination of epipharyngeal volume changes with velopharyngeal muscle function. Design This was a case control study, using consecutive samples. Setting This study took place at the Cleft Palate Rehabilitation Center of the University of Mainz, Germany. Patients Subjects were 29 consecutive cleft lip and palate (CLP) patients and 31 controls (21 patients with dysgnathia and 10 healthy volunteers). Intervention A series of transnasal acoustic measurements (pressure wave: 55 dB for 2 milliseconds) of epipharyng…