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Perfusion Response (perfusion + response)

Distribution by Scientific Domains

Medical Sciences	100%

Selected Abstracts

The influence of exercise on foot perfusion in diabetes

DIABETIC MEDICINE, Issue 10 2007
D. T. Williams
Abstract Aims, Diabetic foot disease is associated with both macro- and microvascular disease. Exercise has both positive and negative effects on the perfusion of lower limbs with peripheral arterial occlusive disease (PAOD). We aimed to measure changes in foot perfusion following a brief period of lower-limb exercise in individuals with and without Type 2 diabetes and non-critical PAOD. Methods, Subjects were allocated to groups according to the presence or absence of diabetes, PAOD on colour duplex imaging and clinically detectable peripheral neuropaÍthy. Transcutaneous oxygen tension (TcPO2), transcutaneous carbon dioxide tension (TcPCO2), ankle-brachial pressure indices, toe pressures and toe-brachial pressure indices (TBI) were measured. Results, One hundred and sixteen limbs were studied in 61 subjects. Post-exercise, toe pressure and TBI increased in the non-diabetic group with arterial disease, but not in the groups with diabetes. Foot TcPO2 values increased in groups with diabetes and TcPCO2 decreased in all groups with arterial disease. Increased chest TcPO2 and decreased TcPCO2 were demonstrated in the groups with diabetes. Conclusions, Elevations in foot TcPO2 and reductions in TcPCO2 indicate improved cutaneous perfusion response to local heating post-exercise. Elevated toe pressures in the non-diabetes group suggest that improved perfusion may be associated with enhanced lower limb macrovascular haemodynamics. However, improvements in TcPO2 and TcPCO2 at foot and chest sites in diabetes imply a global change in cutaneous perfusion. The results suggest that brief exercise results in an improvement in cutaneous perfusion in non-critical PAOD, particularly in individuals with diabetes. [source]

Abnormal vascular reactivity at rest and exercise in obese boys

EUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 2 2009
L. Karpoff
Abstract Background, Obese children exhibit vascular disorders at rest depending on their pubertal status, degree of obesity, and level of insulin resistance. However, data regarding their vascular function during exercise remain scarce. The aims of the present study were to evaluate vascular morphology and function at rest, and lower limb blood flow during exercise, in prepubertal boys with mild-to-moderate obesity and in lean controls. Materials and methods, Twelve moderately obese prepubertal boys [Body Mass Index (BMI: 23·9 ± 2·6 kg m,2)] and thirteen controls (BMI:17·4 ± 1·8 kg m,2), matched for age (mean age: 11·6 ± 0·6 years) were recruited. We measured carotid intima-media thickness (IMT) and wall compliance and incremental elastic modulus, resting brachial flow-mediated dilation (FMD) and nitrate-dependent dilation (NDD), lower limb blood flow during local knee-extensor incremental and maximal exercise, body fat content (DEXA), blood pressure, blood lipids, insulin and glucose. Results, Compared to lean controls, obese boys had greater IMT (0·47 ± 0·06 vs. 0·42 ± 0·03 mm, P < 0·05) but lower FMD (4·6 ± 2·8 vs. 8·8 ± 3·2%, P < 0·01) in spite of similar maximal shear rate, without NDD differences. Lower limb blood flow (mL min,1·100 g,1) increased significantly from rest to maximal exercise in both groups, although obese children reached lower values than lean counterparts whatever the exercise intensity. Conclusions, Mild-to-moderate obesity in prepubertal boys without insulin resistance is associated with impaired endothelial function and blunted muscle perfusion response to local dynamic exercise without alteration of vascular smooth muscle reactivity. [source]

Disparity of activation onset in sensory cortex from simultaneous auditory and visual stimulation: Differences between perfusion and blood oxygenation level-dependent functional magnetic resonance imaging

JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2005
Ho-Ling Liu PhD
Abstract Purpose To compare the temporal behaviors of perfusion and blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) in the detection of timing differences between distinct brain areas, and determine potential latency differences between stimulus onset and measurable fMRI signal in sensory cortices. Materials and Methods Inversion recovery (IR) spin-echo echo-planar imaging (EPI) and T2*-weighted gradient-echo EPI sequences were used for perfusion- and BOLD-weighted experiments, respectively. Simultaneous auditory and visual stimulations were employed in an event-related (ER) paradigm. Signal time courses were averaged across 40 repeated trials to evaluate the onset of activation and to determine potential differences of activation latency between auditory and visual cortices and between these scanning methods. Results Temporal differences between visual and auditory areas ranged from 90,200 msec (root-mean-square (RMS) = 134 msec) and from ,80 to 930 msec (RMS = 604 msec) in perfusion and BOLD measurements, respectively. The temporal variability detected with BOLD sequences was larger between subjects and was significantly greater than that in the perfusion response (P < 0.04). The measured time to half maximum (TTHM) values for perfusion imaging (visual, 3260 ± 710 msec; auditory, 3130 ± 700 msec) were earlier than those in BOLD responses (visual, 3770 ± 430 msec; auditory, 3360 ± 460 msec). Conclusion The greater temporal variability between brain areas detected with BOLD could result from differences in the venous contributions to the signal. The results suggest that perfusion methods may provide more accurate timing information of neuronal activities than BOLD-based imaging. J. Magn. Reson. Imaging 2005;21:111,117. © 2005 Wiley-Liss, Inc. [source]

Comparison of red and green laser doppler imaging of blood flow

LASERS IN SURGERY AND MEDICINE, Issue 3 2004
Andrea K. Murray PhD
Abstract Background and Objectives Laser Doppler imaging (LDI) of perfusion has been performed with a novel green wavelength (532 nm) for comparison with a HeNe laser (633 nm), the aim being validation of the green laser wavelength as a research tool. Study Design/Materials and Methods The effect of wavelength and power on images was investigated and perfusion response following both finger occlusion and local heating of the dorsum were examined as reproducible stimuli for clinical studies. Results The most striking difference between red and green LDI is the absence of veins on green LDI, which are seen with red LDI. Differences have been quantified using vein LDI profiles. Differences were found between blood flow responses imaged by red and green LDI (3 and 5 mW, respectively) for occlusion and heat stimuli. Results are discussed in the context of light penetration. Conclusions Red and green wavelengths appear to image different components of the microcirculation. Lasers Surg. Med. 35:191,200, 2004. © 2004 Wiley-Liss, Inc. [source]