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Respiratory Capacity (respiratory + capacity)
Selected AbstractsImpaired contractile function and mitochondrial respiratory capacity in response to oxygen deprivation in a rat model of pre-diabetesACTA PHYSIOLOGICA, Issue 4 2009M. F. Essop Abstract Aim:, Obesity is a major contributor to the global burden of disease and is closely associated with the development of type 2 diabetes and cardiovascular diseases. This study tested the hypothesis that mitochondrial respiratory capacity of the pre-diabetic heart is decreased leading to impaired contractile function and tolerance to ischaemia/reperfusion. Methods:, Eight-week-old male Wistar rats were fed a high caloric diet for 16 weeks after which anthropometric, metabolic, cardiac and mitochondrial parameters were evaluated vs. age-matched lean controls. Cardiac function (working heart perfusions) and mitochondrial respiratory capacity were assessed at baseline and in response to acute oxygen deprivation. Results:, Rats fed the high caloric diet exhibited increased body weight and visceral fat vs. the control group. Heart weights of obese rats were also increased. Triglyceride, fasting plasma insulin and free fatty acid levels were elevated, while high-density lipoprotein cholesterol levels were reduced in the obese group. Contractile function was attenuated at baseline and further decreased after subjecting hearts to ischaemia-reperfusion. Myocardial infarct sizes were increased while ADP phosphorylation rates were diminished in obese rats. However, no differences were found for mtDNA levels and the degree of oxidative stress-induced damage. Conclusions:, These data show that decreased mitochondrial bioenergetic capacity in pre-diabetic rat hearts may impair respiratory capacity and reduce basal contractile function and tolerance to acute oxygen deprivation. [source] Molecular basis of resistance to cytochrome bc1 inhibitorsFEMS YEAST RESEARCH, Issue 2 2008Nick Fisher Abstract Inhibitors of the mitochondrial respiratory chain enzyme cytochrome bc1 (respiratory complex III) have been developed as antimicrobial agents. They are used in agriculture to control plant pathogenic fungi and in medicine against human pathogens, such as the malaria parasite Plasmodium falciparum, or Pneumocystis jiroveci (an opportunistic pathogenic fungus life-threatening in immuno-compromised patients). These respiratory inhibitors are thus effective against a broad range of important pathogens. Unfortunately, the problem of acquired resistance has rapidly emerged. A growing number of pathogen isolates resistant to inhibitor treatment have been reported, and this resistance is often linked to mutation within cytochrome b, one of the essential catalytic subunits of the complex. Saccharomyces cerevisiae is an invaluable model in order to assess the impact of the mutations on the sensitivity to the drugs, on the respiratory capacity and the fitness of cells. In this minireview, the inhibitors, their mode of action, and the mutations implicated in resistance and studied in yeast are briefly reviewed. Four mutations that are of particular importance in medicine and in agriculture are briefly reviewed and described in more detail and the molecular basis of resistance and of evolution of the mutations is discussed succinctly. [source] The effect of a pulmonary rehabilitation programme on older patients with chronic pulmonary diseaseJOURNAL OF CLINICAL NURSING, Issue 1 2008Kim Ae Kyung RN Aim., The aim of this study was to answer the question: is there an effect on the respiratory capacity and activity tolerance of older patients with chronic obstructive pulmonary disease who participate in a pulmonary rehabilitation programme? Background., Pulmonary rehabilitation is now an integral part of chronic obstructive pulmonary disease management. Evidence supports the positive effects of breath training and exercising training on quality of life, exercise tolerance and improved physical condition of individual with chronic obstructive pulmonary disease. Limited empirical documentation exists to support the effectiveness of a nurse managed rehabilitation programme for older patients with chronic obstructive pulmonary disease. The study was done to evaluate the effects of pulmonary rehabilitation provided by nurses on the pulmonary function, gas exchange and exercise tolerance in older patients with chronic obstructive pulmonary disease. Design., A one group pre-test,post-test design was used to evaluate the effects of a pulmonary rehabilitation programme. Method., The sample consisted of 20 patients with chronic obstructive pulmonary disease who participated in a pulmonary rehabilitation programme including breathing exercises, upper-limb exercises and inspiratory muscle training. Results., The findings indicated improvement in exercise performance and a decrease in dyspnea after participation in the pulmonary rehabilitation programme. Relevance to clinical practice., The clinical nurse can make a significant impact on the illness trajectory and quality of life for patients with chronic obstructive pulmonary disease. The nurse has a critical role in helping patient with chronic obstructive pulmonary disease learn to cope, adjust and adapt to life with a chronic illness. Active nurse involvement with a patient in a pulmonary rehabilitation programme can assist in the identification of factors that motivate the patient, help in establishing realistic out comes expectations and provide patient teaching opportunities. The nurse can assist the patient to develop skills of self-awareness regarding particular symptoms, self-monitoring and health status change identification. [source] Mitochondrial respiration and respiration-associated proteins in cell lines created through Parkinson's subject mitochondrial transferJOURNAL OF NEUROCHEMISTRY, Issue 3 2010A. Raquel Esteves J. Neurochem. (2010) 113, 674,682. Abstract Parkinson's disease (PD) is associated with perturbed mitochondrial function. Studies of cytoplasmic hybrid (cybrid) cell lines containing mitochondria from PD subjects suggest complex I dysfunction in particular is a relatively upstream biochemical defect. To evaluate potential downstream consequences of PD mitochondrial dysfunction, we used a cybrid approach to model PD mitochondrial dysfunction; our cybrid cell lines were generated via transfer of PD or control subject platelet mitochondria to mtDNA-depleted NT2 cells. To confirm our PD cybrid mitochondria did indeed differ from control cybrid mitochondria we measured complex I Vmax activities. Consistent with other PD cybrid reports, relative to control cybrid cell lines the PD cybrid cell line mean complex I Vmax activity was reduced. In this validated model, we used an oxygen electrode to characterize PD cybrid mitochondrial respiration. Although whole cell basal oxygen consumption was comparable between the PD and control cybrid groups, the proton leak was increased and maximum respiratory capacity was decreased in the PD cybrids. PD cybrids also had reduced SIRT1 phosphorylation, reduced peroxisome proliferator-activated receptor-, coactivator-1, levels, and increased NF-kB activation. We conclude mitochondrial respiration and pathways influenced by aerobic metabolism are altered in NT2 cybrid cell lines generated through transfer of PD subject platelet mitochondria. [source] Tolerability and improved protective action of idebenone-loaded pegylated liposomes on ethanol-induced injury in primary cortical astrocytes,JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 7 2004Donatella Paolino Abstract The potential therapeutic advantages of the encapsulation of idebenone within pegylated liposomes were investigated in vitro on primary cortical astrocytes of rats. In particular, both the concentration-dependent effects and the therapeutic effectiveness toward excitotoxic injury, elicited by chronic treatment with ethanol (100 ,M) for 12 days, were evaluated. The following parameters were taken into consideration to assay free or liposomally entrapped idebenone: lactic dehydrogenase release, respiratory capacity measured by tetrazolium salt conversion, glutamine synthetase, and the levels of constitutive and inducible 70-kDa heat shock proteins. To evaluate the effects on astrocytes, three different drug concentrations were used (0.5 ,M, 5 ,M, and 50 ,M). At the highest concentration used (50 ,M), a toxic effect of the free and liposomally entrapped drug was observed. Toxic effects seem to be due to a cellular membrane perturbation, as demonstrated by 45Ca2+ permeation. The therapeutic effect of free or liposomally entrapped idebenone on ethanol-induced injury of primary cortical astrocytes was evaluated as a function of the drug concentration. The drug liposome formulation was much more effective than the free drug in counteracting the ethanol-induced damage in astrocytes, i.e., 10-times-lower doses of liposomally entrapped idebenone are able to provide a greater protective action than the free drug. The improved action of idebenone-loaded liposomes is probably due to the greater drug bioavailability at the cellular level. © 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 93:1815,1827, 2004 [source] Acclimation of snow gum (Eucalyptus pauciflora) leaf respiration to seasonal and diurnal variations in temperature: the importance of changes in the capacity and temperature sensitivity of respirationPLANT CELL & ENVIRONMENT, Issue 1 2000O. K. Atkin ABSTRACT We investigated the relationship between daily and seasonal temperature variation and dark respiratory CO2 release by leaves of snow gum (Eucalyptus pauciflora Sieb. ex Spreng) that were grown in their natural habitat or under controlled-environment conditions. The open grassland field site in SE Australia was characterized by large seasonal and diurnal changes in air temperature. On each measurement day, leaf respiration rates in darkness were measured in situ at 2,3 h intervals over a 24 h period, with measurements being conducted at the ambient leaf temperature. The rate of respiration at a set measuring temperature (i.e. apparent ,respiratory capacity') was greater in seedlings grown under low average daily temperatures (i.e. acclimation occurred), both in the field and under controlled-environment conditions. The sensitivity of leaf respiration to diurnal changes in temperature (i.e. the Q10 of leaf respiration) exhibited little seasonal variation over much of the year. However, Q10 values were significantly greater on cold winter days (i.e. when daily average and minimum air temperatures were below 6° and ,1 °C, respectively). These differences in Q10 values were not due to bias arizing from the contrasting daily temperature amplitudes in winter and summer, as the Q10 of leaf respiration was constant over a wide temperature range in short-term experiments. Due to the higher Q10 values in winter, there was less difference between winter and summer leaf respiration rates measured at 5 °C than at 25 °C. The net result of these changes was that there was relatively little difference in total daily leaf respiratory CO2 release per unit leaf dry mass in winter and summer. Under controlled-environment conditions, acclimation of respiration to growth temperature occurred in as little as 1,3 d. Acclimation was associated with a change in the concentration of soluble sugars under controlled conditions, but not in the field. Our data suggest that acclimation in the field may be associated with the onset of cold-induced photo-inhibition. We conclude that cold-acclimation of dark respiration in snow gum leaves is characterized by changes in both the temperature sensitivity and apparent ,capacity' of the respiratory apparatus, and that such changes will have an important impact on the carbon economy of snow gum plants. [source] | ||||||||||