4,380 research outputs found

    Walking training improves systemic and local pathophysiological processes in intermittent claudication

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    Objective: This study examined the impact of submaximal walking training (WT) on local and systemic nitric oxide (NO) bioavailability, inflammation, and oxidative stress in patients with intermittent claudication (IC). Methods: The study employed a randomised, controlled, parallel group design and was performed in a single centre. Thirty-two men with IC were randomly allocated to two groups: WT (n = 16, two sessions/week, 15 cycles of two minutes walking at an intensity corresponding to the heart rate obtained at the pain threshold interspersed by two minutes of upright rest) and control (CO, n = 16, two sessions/week, 30 minutes of stretching). NO bioavailability (blood NO and muscle nitric oxide synthase [eNOS]), redox homeostasis (catalase [CAT], superoxide dismutase [SOD], lipid peroxidation [LPO] measured in blood and muscle), and inflammation (interleukin-6 [IL-6], C-reactive protein [CRP], tumour necrosis factor α [TNF-α], intercellular adhesion molecules [ICAM], vascular adhesion molecules [VCAM] measured in blood and muscle) were assessed at baseline and after 12 weeks. Results: WT statistically significantly increased blood NO, muscle eNOS, blood SOD and CAT, and muscle SOD and abolished the increase in circulating and muscle LPO observed in the CO group. WT decreased blood CRP, ICAM, and VCAM and muscle IL-6 and CRP and eliminated the increase in blood TNF-α and muscle TNF-α, ICAM and VCAM observed in the CO group. Conclusion: WT at an intensity of pain threshold improved NO bioavailability and decreased systemic and local oxidative stress and inflammation in patients with IC. The proposed WT protocol provides physiological adaptations that may contribute to cardiovascular health in these patients

    Phosphoenolpyruvate carboxylase dentified as a key enzyme in erythrocytic Plasmodium falciparum carbon metabolism

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    Phospoenolpyruvate carboxylase (PEPC) is absent from humans but encoded in thePlasmodium falciparum genome, suggesting that PEPC has a parasite-specific function. To investigate its importance in P. falciparum, we generated a pepc null mutant (D10Δpepc), which was only achievable when malate, a reduction product of oxaloacetate, was added to the growth medium. D10Δpepc had a severe growth defect in vitro, which was partially reversed by addition of malate or fumarate, suggesting that pepc may be essential in vivo. Targeted metabolomics using 13C-U-D-glucose and 13C-bicarbonate showed that the conversion of glycolytically-derived PEP into malate, fumarate, aspartate and citrate was abolished in D10Δpepc and that pentose phosphate pathway metabolites and glycerol 3-phosphate were present at increased levels. In contrast, metabolism of the carbon skeleton of 13C,15N-U-glutamine was similar in both parasite lines, although the flux was lower in D10Δpepc; it also confirmed the operation of a complete forward TCA cycle in the wild type parasite. Overall, these data confirm the CO2 fixing activity of PEPC and suggest that it provides metabolites essential for TCA cycle anaplerosis and the maintenance of cytosolic and mitochondrial redox balance. Moreover, these findings imply that PEPC may be an exploitable target for future drug discovery

    A binary engine fuelling HD87643' s complex circumstellar environment, using AMBER/VLTI

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    International audienceContext. The star HD 87643, exhibiting the “B[e] phenomenon”, has one of the most extreme infrared excesses for this object class. It harbours a large amount of both hot and cold dust, and is surrounded by an extended reïŹ‚ection nebula. Aims. One of our major goals was to investigate the presence of a companion in HD87643. In addition, the presence of close dusty material was tested through a combination of multi-wavelength high spatial resolution observations. Methods. We observed HD 87643 with high spatial resolution techniques, using the near-IR AMBER/VLTI interferometer with baselines ranging from 60 m to 130 m and the mid-IR MIDI/VLTI interferometer with baselines ranging from 25 m to 65 m. These observations are complemented by NACO/VLT adaptive-optics-corrected images in the K and L-bands, ESO-2.2m optical Wide-Field Imager large-scale images in the B, V and R-bands, Results. We report the direct detection of a companion to HD 87643 by means of image synthesis using the AMBER/VLTI instrument. The presence of the companion is conïŹrmed by the MIDI and NACO data, although with a lower conïŹdence. The companion is separated by ∌ 34 mas with a roughly north-south orientation. The period must be large (several tens of years) and hence the orbital parameters are not determined yet. Binarity with high eccentricity might be the key to interpreting the extreme characteristics of this system, namely a dusty circumstellar envelope around the primary, a compact dust nebulosity around the binary system and a complex extended nebula witnessing past violent ejections

    Comparison of flow characteristics and vascular reactivity of radial artery and long saphenous vein grafts [NCT00139399]

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    BACKGROUND: The morphological and functional differences between arteries and veins may have implications on coronary artery bypass graft (CABG) survival. Although subjective differences have been observed between radial artery (RA) and long saphenous venous (LSV) grafts, these have not been quantified. This study assessed and compared the flow characteristics and in-vivo graft flow responses of RA and LSV aorto-coronary grafts. METHODS: Angiograms from 52 males taken 3.7 ± 1.0 months after CABG surgery were analyzed using adjusted Thrombolysis in Myocardial Infarction (TIMI) frame count. Graft and target coronary artery dimensions were measured using quantitative coronary angiography. Estimated TIMI velocity (V(E)) and volume flow (F(E)) were then calculated. A further 7 patients underwent in-vivo graft flow responses assessments to adenosine, acetylcholine and isosorbide dinitrate (ISDN) using intravascular Doppler. RESULTS: The V(E )for RA grafts was significantly greater than LSV grafts (P = 0.002), however there was no difference in volume F(E )(P = 0.20). RA grafts showed positive endothelium-dependent and -independent vasodilatation, and LSV grafts showed no statistically significant response to adenosine and acetylcholine. There was no difference in flow velocity or volume responses. Seven RA grafts (11%) had compromised patency (4 (6%) ≄ 50% stenosis in the proximal/distal anastomoses, and 3 (5%) diffuse narrowing). Thirty-seven (95%) LSV grafts achieved perfect patency and 2 (5%) were occluded. CONCLUSION: The flow characteristics and flow responses of the RA graft suggest that it is a more physiological conduit than the LSV graft. The clinical relevance of the balance between imperfect patency versus the more physiological vascular function in the RA graft may be revealed by the 5-year angiographic follow-up of this trial

    Identification of myocardial diffuse fibrosis by 11 heartbeat MOLLI T1 mapping: averaging to improve precision and correlation with collagen volume fraction

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    Objectives: Our objectives involved identifying whether repeated averaging in basal and mid left ventricular myocardial levels improves precision and correlation with collagen volume fraction for 11 heartbeat MOLLI T1 mapping versus assessment at a single ventricular level. Materials and methods: For assessment of T1 mapping precision, a cohort of 15 healthy volunteers underwent two CMR scans on separate days using an 11 heartbeat MOLLI with a 5(3)3 beat scheme to measure native T1 and a 4(1)3(1)2 beat post-contrast scheme to measure post-contrast T1, allowing calculation of partition coefficient and ECV. To assess correlation of T1 mapping with collagen volume fraction, a separate cohort of ten aortic stenosis patients scheduled to undergo surgery underwent one CMR scan with this 11 heartbeat MOLLI scheme, followed by intraoperative tru-cut myocardial biopsy. Six models of myocardial diffuse fibrosis assessment were established with incremental inclusion of imaging by averaging of the basal and mid-myocardial left ventricular levels, and each model was assessed for precision and correlation with collagen volume fraction. Results: A model using 11 heart beat MOLLI imaging of two basal and two mid ventricular level averaged T1 maps provided improved precision (Intraclass correlation 0.93 vs 0.84) and correlation with histology (R2 = 0.83 vs 0.36) for diffuse fibrosis compared to a single mid-ventricular level alone. ECV was more precise and correlated better than native T1 mapping. Conclusion: T1 mapping sequences with repeated averaging could be considered for applications of 11 heartbeat MOLLI, especially when small changes in native T1/ECV might affect clinical management
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