Neurovascular Response to Pressure in Patients With Diabetic Foot Ulcer.

Diabetic foot ulcer (DFU) is a problem worldwide, and prevention is crucial. We hypothesized that the inability of the skin to respond to pressure is involved in DFU pathogenesis and could be an important predictive factor to take into account. We included 29 patients with DFU and 30 patients with type 2 diabetes without DFU.

VEGF-A promotes both pro-angiogenic and neurotrophic capacities for nerve recovery after compressive neuropathy in rats.

Nerve recovery following injury is usually incomplete, leaving functional deficits. Our aim was to investigate the neural changes in pro-angiogenic, pro-inflammatory and apoptotic factors during and after chronic nerve compression (CNC). Nerve function was impaired after CNC and was progressively restored after nerve decompression, while nerve blood flow was elevated.

Effect of ageing on tactile transduction processes.

With advancing age, a decline in the main sensory modalities including touch sensation and perception is well reported to occur. This review mainly outlines the peripheral components of touch perception highlighting ageing influences on morphological and functional features of cutaneous mechanical transducers and mechanosensitive ion channels, sensory innervation, neurotransmitters and even vascular system required to ensure efferent function of the afferent nerve fibres in the skin. This, in conjunction with effect of ageing on the skin per se and central nervous system, could explain the tactile deficit seen among the ageing population.

Asic3 is a neuronal mechanosensor for pressure-induced vasodilation that protects against pressure ulcers.

Pressure-induced vasodilation (PIV) delays the decrease in cutaneous blood flow produced by local application of low pressure to the skin, a physiologically appropriate adjustment of local vasomotor function. Individuals without a normal PIV response have a high risk of ulceration. Here we demonstrate that acid-sensing ion channel 3 (Asic3) is an essential neuronal sensor for the vasodilation response to direct pressure in both humans and rodents and for protecting against pressure ulcers in mice.

Chronic sciatic nerve injury impairs the local cutaneous neurovascular interaction in rats.

Most studies of chronic nerve compression focus on large nerve function in painful conditions, and only few studies have assessed potential changes in the function of small nerve fibers during chronic nerve compression and recovery from compression. Cutaneous pressure-induced vasodilation is a neurovascular phenomenon that relies on small neuropeptidergic fibers controlling the cutaneous microvasculature. We aimed to characterize potential changes in function of these small fibers and/or in cutaneous microvascular function following short-term (1-month) and long-term (6-month) nerve compression and after release of compression (ie, potential recovery of function).

What can current stimulation tell us about the vascular function of endogenous prostacyclin in healthy rat skin in vivo?

In endothelial function, prostacyclin (PGI(2)) is as important as nitric oxide (NO); however, no test assesses specifically the vascular function of endogenous PGI(2). We hypothesized that PGI(2) has a dominant role in cathodal current-induced vasodilation (CIV) described in human skin. We thus aimed to study, in physiological conditions, the PGI(2) involvement in cathodal CIV in rats in order to use pharmacological blockers that could not be used in humans.

Variability and short-term determinants of walking capacity in patients with intermittent claudication.

Objective: Global positioning system (GPS) recordings can provide valid information on walking capacity in patients with peripheral arterial disease (PAD) and intermittent claudication (IC) during community-based outdoor walking. This study used GPS to determine the variability of the free-living walking distance between two stops (WDBS), induced by lower-limb pain, which may exist within a single stroll in PAD patients with IC and the potential associated parameters obtained from GPS analysis.

Methods: This cross-sectional study of 57 PAD patients with IC was conducted in a university hospital.

A normal penile pressure cannot rule out the presence of lesions on the arteries supplying the hypogastric circulation in patients with arterial claudication.

Proximal claudication remains a difficult diagnosis. The ankle to brachial index may be insensitive in the case of isolated hypogastric lesions. Penile pressure represents an alternative method for proximal arteries.

Aging-associated sensory neuropathy alters pressure-induced vasodilation in humans.

Healthy skin is protected from pressure-induced ischemic damage because of the presence of pressure-induced vasodilation (PIV). PIV relies on small sensory nerve fibers and endothelial function. Since aging alters both nervous and vascular functions, we hypothesized that PIV is altered with aging.

Axon-reflex cutaneous vasodilatation is impaired in type 2 diabetic patients receiving chronic low-dose aspirin.

Low-dose aspirin is largely but non-homogeneously used in primary prevention of cardiovascular complication in type-2 diabetic patients. We hypothesised that low-dose aspirin could interfere with the cutaneous neurovascular responses in type-2 diabetic patients. Galvanic current-induced vasodilatation (CIV) is an original non-noxious integrative model of neurovascular interaction and is impaired under low-dose aspirin in healthy subjects.

Microvascular endothelial function in obstructive sleep apnea: Impact of continuous positive airway pressure and mandibular advancement.

Objectives: Endothelial dysfunction has been proposed as a potential mechanism implicated in the pathogenesis of cardiovascular complications of obstructive sleep apnea syndrome (OSAS). This study aimed to evaluate the microvascular endothelial function (MVEV) in OSAS and the impact on MVEF of 2 months of treatment with continuous positive airway pressure (CPAP) and mandibular advancement device (MAD).

Methods: Microvascular reactivity was assessed using laser Doppler flowmetry combined with acetylcholine (Ach) and sodium nitroprusside (SNP) iontophoresis in 24 OSAS patients and 9 control patients.

Functional assessment at the buttock level of the effect of aortobifemoral bypass surgery.

Background: Little is known about the prevalence of proximal (hip, buttock, lower back) claudication after aortobifemoral bypass (AF2B) grafting and its hemodynamic effects at the buttock level.

Methods: Forty-eight patients performed a treadmill test before and within 6 months after AF2B. The San Diego Claudication Questionnaire and the chest-corrected decrease from rest of transcutaneous oxygen pressure on buttocks were used to study exercise-induced proximal claudication and regional pelvic blood flow impairment.

Measurement of walking distance and speed in patients with peripheral arterial disease: a novel method using a global positioning system.

Background: The maximal walking distance (MWD) performed on a treadmill test remains the "gold standard" in estimating the walking capacity of patients who have peripheral arterial disease with intermittent claudication, although treadmills are not accessible to most physicians. We hypothesized that global positioning system (GPS) recordings could monitor community-based outdoor walking and provide valid information on walking capacity in patients with peripheral arterial disease.

Methods And Results: We studied 24 patients (6 women) with arterial claudication (median [25th to 75th percentile] values: 57 years old [48 to 67 years], 169 cm tall [164 to 172 cm], weight 81 kg [71 to 86 kg], and ankle-brachial index 0.

Endothelium-derived hyperpolarizing factor as an in vivo back-up mechanism in the cutaneous microcirculation in old mice.

There is now strong evidence that an endothelium-derived hyperpolarizing factor (EDHF), other than nitric oxide (NO) or prostaglandin (PG), exists for dilating arteries and arterioles. In vitro studies on isolated vessels pointed out a role for EDHF as a back-up mechanism when the NO pathway is impaired, but there was a lack of in vivo studies showing a functional role for EDHF. Ageing has pronounced effects on vascular function and particularly on endothelium-dependent relaxation, providing a novel situation in which to assess the contributions of EDHF.

Study of human outdoor walking with a low-cost GPS and simple spreadsheet analysis.

Purpose: To determine whether a low-cost, commercially available global positioning system (GPS) can be used to study outdoor walking of healthy subjects, allowing the detection of walking and resting (nonwalking) periods and the accurate estimation of speed and distance of each walking periods.

Methods: The same EGNOS-enabled GPS receiver was used for all experiments. In experiment 1, various signal-processing methodologies were tested for the detection of both walking and resting bouts from a prescribed walking protocol (PWP) that was performed 21 times by six healthy subjects on an outdoor athletic track.

Altered acetylcholine, bradykinin and cutaneous pressure-induced vasodilation in mice lacking the TREK1 potassium channel: the endothelial link.

The TWIK related K+ channel TREK1 is an important member of the class of two-pore-domain K+ channels. It is a background K+ channel and is regulated by hormones, neurotransmitters, intracellular pH and mechanical stretch. This work shows that TREK1 is present both in mesenteric resistance arteries and in skin microvessels.

High prevalence of proximal claudication among patients with patent aortobifemoral bypasses.

Background: Proximal (ie, buttock, hip) claudication can result from impaired perfusion in the hypogastric area after aortobifemoral bypass (ABF) despite normal femorodistal blood flow provided by the patent bypass. The proportion of patients that experience proximal claudication after ABF is unknown, and arguments for the vascular origin of symptoms specifically at the proximal level have never been reported.

Methods: This was a prospective study set in an institutional practice of ambulatory patients referred for a systematic survey of their previous ABF bypass.

Neuroendocrine pathway involvement in the loss of the cutaneous pressure-induced vasodilatation during acute pain in rats.

Pain is regarded as a risk factor in pressure ulcer development by contributing to immobility. Pressure-induced vasodilatation (PIV) is a mechanism whereby cutaneous blood flow increases in response to progressive locally applied pressure, thereby delaying the occurrence of ischaemia and appearing to be a protective response to local pressure. When the interaction between nervous and vascular systems is deregulated, PIV, which relies on both systems, is absent.

Estimation of the functional role of arterial pathways to the buttock circulation during treadmill walking in patients with claudication.

The aim of the study was to estimate the functional contribution of the arterial inflow pathways to the pelvic circulation during walking in patients with stage 2 lower extremity arterial disease. Transcutaneous oxygen pressure (Ptc(O(2))) changes during exercise can be used to estimate the severity of regional blood flow impairment while walking. Seventy patients with stable lower limb claudication were studied using a multivariate linear regression model.

Simultaneous arterial pressure recordings improve the detection of endofibrosis.

Purpose: Exercise improves the diagnostic performance of ankle-to-brachial index (ABI) in the detection of exercise-induced arterial endofibrosis (EIAE). Pressure values for all four limbs are required to calculate ABI, but rapid systemic pressure changes occur during the recovery period from exercise. We checked whether after exercise, ABI calculated from simultaneous measurements was better than from consecutive measurements for differentiating athletes with EIAE from normal athletes.

Aldose reductase pathway inhibition improved vascular and C-fiber functions, allowing for pressure-induced vasodilation restoration during severe diabetic neuropathy.

Pressure-induced vasodilation, a neurovascular mechanism relying on the interaction between mechanosensitive C-fibers and vessels, allows skin blood flow to increase in response to locally nonnociceptive applied pressure that in turn may protect against pressure ulcers. We expected that severe neuropathy would dramatically affect pressure-induced vasodilation in diabetic mice, and we aimed to determine whether pressure-induced vasodilation alteration could be reversed in 8-week diabetic mice. Control and diabetic mice received no treatment or sorbinil, an aldose reductase inhibitor, or alagebrium, an advanced glycation end product breaker, the last 2 weeks of diabetes.

The physiological response of ankle systolic blood pressure and ankle to brachial index after maximal exercise in athletes is dependent on age.

The development of sports activities in the over forties has increased the number of middle-aged patients performing heavy-load exercise. The normal response of ankle systolic blood pressure (ASBP) and ankle to brachial index (ABI) to intense exercise is known in young athletes, but little is known for other age groups. Three groups of 21 athletes: <20 (G1), 20-40 (G2), and >40 (G3) years old, respectively, were studied.