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At least 19 recordsLinked to original sources
PubMed1987

Rheological properties controlling mucociliary frequency and respiratory mucus transport.

Respiratory mucus and mucosa possess highly hydrophilic structures which are difficult to preserve using standard fixative methods. The close interaction between cilia and mucus can be observed after instantaneously interrupting the ciliary movement using ultra rapid and cryosubstitution fixation methods. Mucus possess several rheological properties such as pseudoplasticity, elastothixotropy, spinability and adhesiveness. Rheological properties of mucus may control, per se, the ciliary beating frequency. By measuring the mucociliary frequency on the excised mucus-depleted frog palate of native mucus and xanthan gum using a simulant of mucus, we observed that beyond an optimal value of viscosity (close to 12 Pa.s) the mucociliary frequency and transport rate decrease in parallel. Other rheological factors such as adhesion and spinability of mucus can also be implicated in the regulation of the mucociliary transport rate.

Animals↗
PubMed1996

[Human hemoglobin structure and respiratory transport].

Hemoglobin carries oxygen from the lungs to the tissues and helps to transport carbon dioxide back to the lungs. It fulfills this dual role by clicking back and forth between two alternative structures, designated T for tense and R for relaxed, which are defined by the theory of allostery. Like all proteins, it is made up of small molecules called amino acids. A hemoglobin molecule is made up of four polypeptide chains, two alpha chains of 141 amino acid residues each and two beta chains of 146 amino acid residues each. In the complete molecule, four subunits are closely joined, as in a three-dimensional jigsaw puzzle, to form a tetramer. In the T structure, the subunits of the molecule are clamped by salt bridges and hydrogen bonds against the pressure of springs and their narrow pockets impede the entry of oxygen. In the R structure, all the clamps have sprung open and the heme pockets are open wide enough to admit oxygen easily. Uptake of oxygen by the T structure would strain the clamps until they all burst open in concert and allow the molecule to relax to the R structure. Loss of oxygen will narrow the heme pockets and allow the T structure to re-form.

Allosteric Regulation↗
PubMed1996

Respiratory issues in aeromedical patient transport.

Respiratory considerations in aeromedically evacuated patients are the cornerstone of safe, successful transport. Maintenance of the ABCs and ongoing resuscitation including pulmonary/ventilator stabilization and management en route are paramount. All of these goals are predicated on a well-developed understanding of hypobaric pulmonary physiology and hypobaric effects on medical devices, a solid grasp of the inherent limits of an aeromedical environment, and the resolute accomplishment of both initial and follow-up team member training.

Air Ambulances↗
PubMed1974

Preliminary characterization studies on the Neisseria catarrhalis respiratory electron transport chain.

The Neisseria catarrhalis respiratory electron transport system was examined in a sonic type particulate membrane fraction and shown to have a moderately active succinate as well as nonpyridine nucleotide-dependent dl-lactate oxidoreductase and a very active tetramethyl-p-phenylenediamine oxidase. l-Malate and l-glutamate oxidation were found to be dependent on pyridine nucleotides and exclusively associated with a soluble (or nonmembranous) fraction. The primary cytochrome components in the electron transport system appear to be c-type in nature (555 nm and 550 nm) as well as cytochrome a(1) (600 nm) and cytochrome o.

Cell Membrane↗
PubMed2005

EPR study of electron transport in the cyanobacterium Synechocystis sp. PCC 6803: oxygen-dependent interrelations between photosynthetic and respiratory electron transport chains.

In this work, we investigated electron transport processes in the cyanobacterium Synechocystis sp. PCC 6803, with a special emphasis focused on oxygen-dependent interrelations between photosynthetic and respiratory electron transport chains. Redox transients of the photosystem I primary donor P700 and oxygen exchange processes were measured by the EPR method under the same experimental conditions. To discriminate between the factors controlling electron flow through photosynthetic and respiratory electron transport chains, we compared the P700 redox transients and oxygen exchange processes in wild type cells and mutants with impaired photosystem II and terminal oxidases (CtaI, CydAB, CtaDEII). It was shown that the rates of electron flow through both photosynthetic and respiratory electron transport chains strongly depended on the transmembrane proton gradient and oxygen concentration in cell suspension. Electron transport through photosystem I was controlled by two main mechanisms: (i) oxygen-dependent acceleration of electron transfer from photosystem I to NADP(+), and (ii) slowing down of electron flow between photosystem II and photosystem I governed by the intrathylakoid pH. Inhibitor analysis of P700 redox transients led us to the conclusion that electron fluxes from dehydrogenases and from cyclic electron transport pathway comprise 20-30% of the total electron flux from the intersystem electron transport chain to P700(+).

Electron Spin Resonance Spectroscopy↗
PubMed2003

Photosynthetic and respiratory electron transport in the alkaliphilic cyanobacterium Arthrospira (Spirulina) platensis.

Photosynthetic and respiratory electron transport and their interplay with ion transport have been studied in Arthrospira platensis, a filamentous alkaliphilic cyanobacterium living in hypersaline lakes. As typical for alkaliphiles, A. platensis apparently does not maintain an outward positive pH gradient at its plasma membrane. Accordingly, sodium extrusion occurs via an ATP-dependent primary sodium pump, in contrast to the Na(+)/H(+) antiport in most cyanobacteria. A. platensis is strongly dependent on sodium/bicarbonate symport for the uptake of inorganic carbon. Sodium extrusion in the presence of the Photosystem II inhibitor diuron indicates that a significant amount of ATP is supplied by cyclic electron transport around Photosystem I, the content of which in A. platensis is exceptionally high. Plastoquinol is oxidized by two parallel pathways, via the cytochrome b (6) f complex and a putative cytochrome bd complex, both of which are active in the light and in the dark.

Journal Article↗
PubMed1980

Terminal branching of the respiratory electron transport chain in Neisseria meningitidis.

The respiratory components of the envelope membrane preparation of Neisseria meningitidis were investigated. Oxidase activities were demonstrated in this fraction in the presence of succinic acid, reduced nicotinamide adenine dinucleotide, and ascorbate-N,N,N',N'-tetramethyl-p-phenylene-diamine (TMPD). Differences in the kinetics of inhibition by terminal oxidase inhibitors on the three oxidase activities indicated that ascorbate-TMPD oxidation involved only an azide-sensitive oxidase, whereas oxidation of the physiological substrates involved two oxidases, one of which was relatively azide resistant. Spectrophotometric studies revealed that ascorbate-TMPD donated its electrons exclusively to cytochrome o, whereas the physiological substrates were oxidized via both cytochromes o and a. The effects of class II inhibitors on the oxidases suggest terminal branching of the electron transport chain at the cytochrome b level. A model of the respiratory system in N. meningitidis is proposed.

Ascorbic Acid↗
PubMed2000

Influence of cytoskeletal agents on the respiratory electron transport pathways in the cells of winter wheat leaves.

The effects of actin and tubulin polymerization inhibitors on the respiratory electron transport pathway activities were investigated using abscisic acid (ABA)- and cold-treated winter wheat seedling leaves. In unstressed control plants, cytochalasin B (15 microm) decreased the capacity of the cytochrome pathway, but stimulated the cyanide-resistant pathway, whereas oryzalin (15 microm) produced the opposite effects. Cold hardening (3 degrees C for 7 days) and ABA treatment 30 microm changed the respiratory pattern in a similar manner to cytochalasin B but to lesser effects. This points to cold- and ABA-induced reduction in microfilament sensitivity to these drugs and hence stabilization of actin-dependent processes. In contrast, oryzalin had only weak effects on control samples and its effects were strengthened in the presence of the cytoskeleton-modifying factors. The data suggest that the potential targets for the agent either increase and/or the degree of involvement of microtubules in the respiratory chain regulation, and therefore that the cytoskeleton can modify the functioning of the respiratory electron transport pathways in winter wheat cells.

Abscisic Acid↗
PubMed1993

Deleterious effects of disulfiram on the respiratory electron transport system of liver mitochondria.

1. The mechanism of action of disulfiram on the respiratory electron transport system of the liver mitochondria was studied in vitro. 2. Disulfiram inhibited the respiration supported by malate-glutamate as well as succinate. 3. Mitochondrial respiration inhibition was dependent upon alteration of -SH groups. 4. The inhibitory action of disulfiram might be related to the crosslinking of several proteins of the inner mitochondrial membrane. 5. The effects described above could be attributed to disulfiram per se and not to the main metabolite diethyldithiocarbamate.

Cytochrome b Group↗
PubMed1979

Respiratory gas transport by the incompletely separated double circulation in the bullfrog, Rana catesbeiana.

To investigate respiratory gas transport in the bullfrog, Rana catesbeiana (mean body weight 249 g. ambient temperature 25 degrees C), O2 uptake and CO2 output were determined, and blood gas parameters (PO2, PCO2, pH, O2 content, O2 capacity and hematocrit) were measured in blood samples taken from various heart cavities and blood vessels. Analysis of the data on the basis of a simplified circulatory gas transport model allowed to estimate the cardiac output and its distribution, and to describe the O2 and CO2 exchange in lungs, skin and tissues. The total cardiac output (average 20.5 ml/min) was estimated to be distributed about equally to the pulmocutaneous (56%) and systemic arterial vessels (44%), whereas the systemic venous return (62%) was larger than the pulmonary venous return (38%). The marked difference in oxygenation between aortic and pulmocutaneous arterial blood (average O2 saturation 85% and 47%, respectively) showed a highly effective separation of systemic venous and pulmonary venous blood in the ventricle and conus arteriosus. After enlargement of the ventricle produced by incision of the pericardium, the separation of arterialized and venous blood was markedly reduced, but not abolished.

Animals↗
PubMed1990

Do photosynthetic and respiratory electron transport chains share redox proteins?

In purple nonsulfur bacteria and cyanobacteria, there is close interaction between the photosynthetic and respiratory electron transport chains, which share identical redox proteins. Recent findings that the thylakoid membranes of eukaryotic chloroplasts may have respiratory functions suggest that the interaction of photosynthesis and respiration may be a common feature of all photosynthetic cells.

Cytochrome c Group↗
PubMedDate not supplied

Effects of orientation, intermittent rest and vehicle cleaning during transport on development of transport-related respiratory disease in horses.

The effects of various factors on the inflammatory and stress response in horses during transportation were examined in Experiments 1 and 2, carried out in April and August, respectively. In Experiment 1, three groups (G1-G3) of four Thoroughbreds were used, and in Experiment 2, two groups (G4, G5). G1 animals were loaded into lorries with their heads facing forwards (FF) and given periods of short rest (SR) (30 min for every 4 h driven). G2 horses were loaded facing rearwards (FR) and given SR. G3 horses were FF and given periods of long rest (LR) (2 h rest for every 4 h driven). G4 horses were transported FF with hay suspended in front of them and no cleaning of faeces or urine during rest stops. G5 horses were FF and given pellets instead of hay, and the lorry was cleaned and washed at each rest stop. G4 and G5 horses were rested for 1 h after every 5 h of driving. All groups were driven a distance of 1500 km, and the total journey time was 37 h for G1 and G2, 49 h for G3, and 40 h for G4 and G5. In Experiment 1, indicators of inflammatory and stress responses tended to be highest in G1, intermediate in G2 and lowest in G3. In Experiment 2 they tended to be higher in G4 than in G5. The results suggested that increasing the rest time and cleaning the interior of the vehicle during rest stops reduced transportation stress and respiratory insults, factors that may lead to respiratory disease.

Animal Husbandry↗
PubMed1980

Bronchial bifurcations and respiratory mass transport.

A new transport mechanism explains the importance of the shape of bronchial bifurcations in the transfer of gases and particles between the atmosphere and the alveoli. Photographs of flow visualization experiments illustrate the effect in models of bronchial branching. The mechanism provides a means of nondiffusional transport that helps to explain normal respiratory exchange of gases as well as successful ventilation with very low tidal volumes, as in some lung diseases and in the high-frequency panting of dogs.

Animals↗
PubMed1991

The response of intact Strongyloides ratti infective (L3) larvae to substrates and inhibitors of respiratory electron transport.

Live, intact third-stage larvae (L3s) of Strongyloides ratti in the absence of exogenous substrates consumed oxygen at a rate (E-QO2) of 181.8 +/- 12.4 ng atoms min-1 mg dry weight-1 at 35 degrees C. Respiratory electron transport (RET) Complex I inhibitor rotenone (2 microM) produced 33 +/- 6.5% inhibition of the E-QO2. Unusually the rotenone-induced inhibition was not relieved by 5 mM-succinate. The E-QO2 of intact L3s was refractory to RET Complex III inhibitor antimycin A at 2 microM; 4 microM-antimycin inhibited less than or equal to 10% of the E-QO2. The electron donor couple ascorbate/TMPD augmented the E-QO2 in the presence of rotenone (2 microM) and antimycin A (4 microM) by 110%. Azide (1 mM) stimulated the antimycin A refractory QO2 by 36.6 +/- 7.2% which was only partially inhibited by 1.0 mM-KCN (IC50 = 0.8 mM). The data suggest the presence of classical (CPW) and alternate (APW) electron transport pathways in S. ratti L3s.

Animals↗