Electrical stimulation of human lower extremities enhances energy consumption, carbohydrate oxidation, and whole body glucose uptake.
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Our laboratory has recently demonstrated that low-frequency electrical stimulation (ES) of quadriceps muscles alone significantly enhanced glucose disposal rate (GDR) during euglycemic clamp (Hamada T, Sasaki H, Hayashi T, Moritani T, and Nakao K. J Appl Physiol 94: 2107-2112, 2003). The present study is further follow-up to examine the acute metabolic effects of ES to lower extremities compared with voluntary cycle exercise (VE) at identical intensity. In eight male subjects lying in the supine position, both lower leg (tibialis anterior and triceps surae) and thigh (quadriceps and hamstrings) muscles were sequentially stimulated to cocontract in an isometric manner at 20 Hz with a 1-s on-off duty cycle for 20 min. Despite small elevation of oxygen uptake by 7.3 +/- 0.3 ml x kg(-1) x min(-1) during ES, the blood lactate concentration was significantly increased by 3.2 +/- 0.3 mmol/l in initial period (5 min) after the onset of the ES (P < 0.01), whereas VE showed no such changes at identical oxygen uptake (7.5 +/- 0.3 ml x kg(-1) x min(-1)). ES also induced enhanced whole body carbohydrate oxidation as shown by the significantly higher respiratory gas exchange ratio than with VE (P < 0.01). These data indicated increased anaerobic glycolysis by ES. Furthermore, whole body glucose uptake determined by GDR during euglycemic clamp demonstrated a significant increase during and after the cessation of ES for at least 90 min (P < 0.01). This post-ES effect was significantly greater than that of the post-VE period (P < 0.01). These results suggest that ES can substantially enhance energy consumption, carbohydrate oxidation, and whole body glucose uptake at low intensity of exercise. Percutaneous ES may become a therapeutic utility to enhance glucose metabolism in humans. (+info)
Common stress fractures.
(50/1399)
Lower extremity stress fractures are common injuries most often associated with participation in sports involving running, jumping, or repetitive stress. The initial diagnosis can be made by identifying localized bone pain that increases with weight bearing or repetitive use. Plain film radiographs are frequently unrevealing. Confirmation of a stress fracture is best made using triple phase nuclear medicine bone scan or magnetic resonance imaging. Prevention of stress fractures is most effectively accomplished by increasing the level of exercise slowly, adequately warming up and stretching before exercise, and using cushioned insoles and appropriate footwear. Treatment involves rest of the injured bone, followed by a gradual return to the sport once free of pain. Recent evidence supports the use of air splinting to reduce pain and decrease the time until return to full participation or intensity of exercise. (+info)
Mechanism of venous valve closure and role of the valve in circulation: a new concept.
(51/1399)
PURPOSE: The purpose of this study was to investigate the blood flow changes and venous wall movements that occur in the perivalvular area during venous flow, to learn how these physiologic events influence the movements of the valve cusps, and to learn how the movements of the valve cusps influence the venous flow. MATERIALS AND METHODS: Twenty healthy volunteers (10 male, 10 female, age 18 to 52) were subjects of this study. Each volunteer was examined in semi-recumbent and standing positions at rest and during active foot movements. Ultrasound examinations were performed in the B-flow mode supplemented by B-mode and pulsed-wave Doppler scanning. RESULTS: Four phases of the valve cycle are described. During the opening phase (0.27 +/- 0.05 s), the cusps move from the closed position toward the sinus wall. After reaching a certain point, the valves cease opening and enter the equilibrium phase. During this phase (0.65 +/- 0.08 s), the leading edges remain suspended in the flowing stream and undergo self-excited oscillations with an amplitude of 0.01 to 0.16 cm. During the closing phase (0.41 +/- 0.07 sec), the leaflets move synchronously toward the center of the vein. The subsequent closed phase has a duration of 0.45 +/- 0.05 seconds when the cusps remain closed. During the equilibrium phase, flow separation occurs at the leading edge of the cusp with reattachment at the wall of sinus. At this point, flow splits into two streams at each valve cusp. Part of the flow is directed into the sinus pocket behind the valve cusp, forming a vortex along the valve cusp before re-emerging in the main stream in the vein. When the valve is maximally open, the two cusps create a narrowing of the lumen about 35% smaller than the vein distal to the valve. In this narrowed area flow accelerates, forming a proximally directed jet. CONCLUSIONS: The valve cusps undergo the four phases constituting the valve cycle. The local hemodynamic events, such as flow separation and reattachment, and vortical flow in the sinus play important roles in the valve operation. In addition to prevention of retrograde flow, the valve acts as a venous flow modulator. The vortical stream behind the valve cusps participates in the operation of the valve, and prevents stasis inside the valve pocket. The central jet possibly facilitates outflow. (+info)
Knockout of ERK5 causes multiple defects in placental and embryonic development.
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BACKGROUND: ERK5 is a member of the mitogen activated protein kinase family activated by certain mitogenic or stressful stimuli in cells, but whose physiological role is largely unclear. RESULTS: To help determine the function of ERK5 we have used gene targeting to inactivate this gene in mice. Here we report that ERK5 knockout mice die at approximately E10.5. In situ hybridisation for ERK5, and its upstream activator MKK5, showed strong expression in the head and trunk of the embryo at this stage of development. Between E9.5 and E10.5, multiple developmental problems are seen in the ERK5-/- embryos, including an increase in apoptosis in the cephalic mesenchyme tissue, abnormalities in the hind gut, as well as problems in vascular remodelling, cardiac development and placental defects. CONCLUSION: Erk5 is essential for early embryonic development, and is required for normal development of the vascular system and cell survival. (+info)
Temporal gene expression profiling of dystrophin-deficient (mdx) mouse diaphragm identifies conserved and muscle group-specific mechanisms in the pathogenesis of muscular dystrophy.
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Mutations in dystrophin are the proximate cause of Duchenne muscular dystrophy (DMD), but pathogenic mechanisms linking the absence of dystrophin from the sarcolemma to myofiber necrosis are not fully known. The muscular dystrophies also have properties not accounted for by current disease models, including the temporal delay to disease onset, broad species differences in severity, and diversity of skeletal muscle responses. To address the mechanisms underlying the differential targeting of muscular dystrophy, we characterized temporal expression profiles of the diaphragm in dystrophin-deficient (mdx) mice between postnatal days 7 and 112 using oligonucleotide microarrays and contrasted these data with published hindlimb muscle data. Although the diaphragm and hindlimb muscle groups differ in severity of response to dystrophin deficiency, and exhibited substantial divergence in some transcript categories including inflammation and muscle-specific genes, our data show that the general mechanisms operative in muscular dystrophy are highly conserved. The two muscle groups principally differed in expression levels of differentially regulated genes, as opposed to the non-conserved induced/repressed transcripts defining fundamentally distinct mechanisms. We also identified a postnatal divergence of the two wild-type muscle group expression profiles that temporally correlated with the onset and progression of the dystrophic process. These findings support the hypothesis that conserved disease mechanisms interacting with baseline differences in muscle group-specific transcriptomes underlie their differential responses to DMD. We further suggest that muscle group-specific transcriptional profiles contribute toward the muscle targeting and sparing patterns observed for a variety of metabolic and neuromuscular diseases. (+info)
Can the Perclose suture-mediated closure system be used safely in patients undergoing diagnostic and therapeutic angiography to treat chronic lower extremity ischemia?
(54/1399)
PURPOSE: Mechanical closure devices for arterial hemostasis after angiography, such as the Perclose suture-mediated closure system, are designed to decrease time to ambulation and improve patient comfort. Although these devices are safe and efficacious, to date there has been little reported about use of the Perclose device in a cohort consisting exclusively of patients with lower extremity peripheral vascular disease. The purpose of this study was to determine the safety and efficacy of routine use of the Perclose system in patients with documented peripheral vascular disease undergoing angiography to treat chronic lower extremity ischemia. METHODS: The Perclose device was placed for arterial closure after femoral artery access in 500 consecutive patients with documented peripheral vascular disease (ankle-brachial index, <0.8) who underwent diagnostic angiography or percutaneous intervention because of chronic lower extremity ischemia. These 500 patients composed 91% of all patients who underwent angiography because of chronic lower extremity ischemia between January 1, 2001, and April 1, 2002. All complications associated with the Perclose device were identified and reviewed. RESULTS: Of the 500 arteries, 54% were accessed for diagnostic angiography and 46% for intervention. Perclose device placement was successful in 475 attempts (95%). Overall major complication rate was 1.4% (7 of 500 arteries). Complications included one death from retroperitoneal hemorrhage; three episodes of limb ischemia, two requiring operation and one requiring lytic therapy; two pseudoaneurysms; and one hematoma, which prolonged hospitalization. The hematoma was the only complication in the 25 patients with failed Perclose device placement. There were no infections requiring admission or operation. CONCLUSION: The Perclose suture-mediated closure device is efficacious and can be used safely in selected patients with documented peripheral vascular disease. Complications associated with this device tend to be more severe than those historically reported for manual compression. Substantial experience with use of this device is required to achieve excellent results in patients with difficult anatomy. (+info)
Leg ulceration as a long-term complication of deep vein thrombosis.
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OBJECTIVE: To evaluate the role of deep vein thrombosis as a cause of leg ulcers. PATIENTS AND METHODS: A population-based, case-control study was conducted in Central and North Auckland, New Zealand. Cases comprised 241 people aged 40 to 99 years and on the electoral roll, with current leg ulcers (all types). Cases were identified by means of notification from health professionals and by self-referral. Controls were 224 people in the same age group, without leg ulcers, who were selected from the electoral roll by using a stratified random sampling process. MAIN OUTCOME MEASURES: The occurrence of leg ulceration as a consequence of exposure to deep vein thrombosis or being at high risk of deep vein thrombosis (that is, people with a family history of deep vein thrombosis, and/or a history of leg fracture and/or hip, leg, or foot surgery). RESULTS: After adjustment for age, sex, and other potential confounding factors, people who had a diagnosed thromboembolism were at almost three times higher risk of having a leg ulcer (odds ratio, 2.92; 95% confidence interval (CI), 1.47 to 6.08). In addition, people who had been at high risk of a venous thrombosis but were not diagnosed with this condition (eg, people with a history of major leg surgery) were also at increased risk of ulceration (odds ratio, 2.25; 95% CI, 1.49-3.42). Overall, 56% (95% CI, 33% - 71%) of leg ulcers were attributed to being at high risk of deep vein thrombosis. CONCLUSIONS: Deep vein thrombosis and factors that place people at high risk of deep vein thrombosis are an important cause of leg ulcers in older people. This finding strengthens the rationale for the routine and long-term use of thromboprophylaxis, particularly in high-risk patients. (+info)
Amputations among diabetics in Reunion Island.
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OBJECTIVES: Our study allowed us to exhaustively list up all the cases of lower limb amputation carried out in the hospitals of the island from May 1st, 2000 to April 30, 2001. METHODS: We studied the medical files of all the diabetic patients having undergone a non traumatic amputation and they all had an interview with an inquiring doctor. RESULTS: 406 amputations (including 11 traumatic ones) have been carried out over the 12 months of our study. On a total of 395 non traumatic amputations, 70% were made among diabetics and concerned 278 patients among whom 179 are type 2 diabetics. Men are more concerned than women. If the distribution of amputation levels does not differ between diabetics and non-diabetics, the former more often undergo multiple interventions. 72% of the patients have a level of primary education, 59% have difficulties reading, and most of them have a very limited knowledge on their disease and do not practise any prevention for podologic traumatism. CONCLUSION: In a region where 718 220 inhabitants live and where the rate of diabetes prevalence is high (17.7% for 30-69 years), we could be afraid for the years to come of an important increase of the prevalence and diabetes chronic complications incidence rates. Authorities have to become aware of the current risks and of increasing equipments and personnel for the prevention and the follow-up of this insidious pathology. Programmes for the prevention of podologic complications should be supported by taking into account local specificities. (+info)