Biochemical and inflammatory changes in the exercising claudicant

Low-Intensity Exercise Training Increases Heart Rate Variability in Patients With Peripheral Artery Disease

Patients with peripheral artery disease (PAD), consistent with others with atherosclerotic occlusive disorders, have autonomic dysfunction (as measured by low heart rate variability [HRV]) that predisposes them to sympathetically mediated cardiac arrhythmias and sudden death. Exercise therapy has been shown to increase HRV in patients with coronary artery disease by increasing parasympathetic modulation of heart rate. This study quantified the circulatory and autonomic effects of a progressive, 12-week home-based, low-intensity (pain-free walking) exercise program in PAD and intermittent claudication. Participants (N = 33, mean age 67.8 8.1 years) were randomly assigned to either a walking group (n = 18), whose members performed a structured, 12-week, progressive walking program 5 days/week for 12 weeks, or a comparison group (n = 15), whose members performed usual activities. Circulatory measures (heart rate, blood pressure, and rate pressure product) and autonomic measures (HRV) were obtained at the beginning (Week 1) and end (Week 12) of the study. Minimal change in circulatory measures occurred. However, spectral analysis of HRV revealed that autonomic function improved significantly in members of the walking group; specifically, there was an increase in parasympathetic and a decrease in sympathetic modulation. Members of the walking group also significantly increased maximal walking distance. These findings suggest that a structured, low-intensity, high-frequency walking program improves autonomic function by increasing HRV in patients with PAD.

Extracorporeal shockwave therapy for the treatment of lower limb intermittent claudication: study protocol for a randomised controlled trial (the SHOCKWAVE 1 trial)

Background

Peripheral arterial disease (PAD) has a population prevalence of 4.6% with intermittent claudication (IC) presenting as one of the earliest and most common symptoms. PAD has detrimental effects on patients’ walking ability in terms of maximum walking distance (MWD) and pain-free walking distance (PFWD). Research has suggested extracorporeal shockwave therapy (ESWT) may induce angiogenesis in treated tissue; therefore, our objective is to assess the tolerability and efficacy of ESWT as a novel treatment of intermittent claudication.

Methods/design

Patients with unilateral claudication will be randomised to receive either ESWT (PiezoWave 2 shockwave system) or sham treatment to the calf muscle bulk three times per week for 3 weeks. All patients are blinded to treatment group, and all assessments will be performed by a masked assessor. Treatment tolerability using a visual analogue scale, ankle-brachial pressure index, MWD, PFWD and safety will all be formally assessed as outcome measures at baseline and at 4, 8 and 12 weeks follow-up.

Discussion

This trial will be the first of its kind in terms of methodology in relation to ESWT for intermittent claudication. A double-masked randomised controlled trial will provide useful information about the potential for the use of ESWT as a non-invasive treatment option and the need for further robust research.

Trial registration

ClinicalTrials.gov, NCT02652078. Registered on 17 October 2014.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-1844-4) contains supplementary material, which is available to authorized users.

High-Density Lipoprotein Subfractions and Cholesterol Efflux Capacity Are Not Affected by Supervised Exercise but Are Associated with Baseline Interleukin-6 in Patients with Peripheral Artery Disease

OBJECTIVE

To quantify the association between high-density lipoprotein (HDL) subfractions, efflux capacity, and inflammatory markers at baseline and the effect of supervised exercise on these HDL parameters in patients with peripheral artery disease (PAD).

METHODS

The study to improve leg circulation (SILC) was a randomized trial of supervised treadmill exercise, leg resistance training, or control in individuals with PAD. In a post hoc cross-sectional analysis, we quantified the associations between baseline HDL subfraction concentrations (HDL2 and HDL3), HDL-C efflux capacity, and inflammatory markers [C-reactive protein (CRP) and interleukin-6 (IL-6)]. We then examined the effect of supervised exercise on changes in these lipoprotein parameters and inflammatory markers in 88 patients from SILC.

RESULTS

Baseline HDL-C efflux capacity was associated with baseline concentrations of HDL2 (β = 0.008, p = 0.0106), HDL3 (β = 0.013, p < 0.0001), and IL-6 (β = -0.019, p = 0.03). Baseline HDL3 concentration was inversely associated with IL-6 concentration (β = -0.99, p = 0.008). Compared to control, changes in HDL2, HDL3, normalized HDL-C efflux capacity, CRP, or IL-6 were not significantly different at 6 months following the structured exercise intervention.

CONCLUSION

HDL efflux and HDL3 were inversely associated with IL-6 in PAD patients. Structured exercise was not associated with changes in HDL subfractions, HDL-C efflux capacity, CRP, and IL-6 in PAD patients. Our preliminary findings support the theory that inflammation may adversely affect HDL structure and function; however, further studies are needed to evaluate these findings.

Potential identification of a claudicant group vulnerable to acute kidney injury

This observational study aimed to investigate the relationship between renal injury, endothelial function and oxidative stress in claudicants undergoing maximal treadmill exercise. Twenty patients with claudication were identified in whom the urinary N-acetyl-β-D-glucosaminidase (β-NAG)/creatinine ratio, plasma oxidative state and endothelial function were tested pre- and post-maximal treadmill walking exercise. Of the 20 participants in this study, the urinary NAG/creatinine (Cr) rose from a pre-exercise level of 8.9, 6.7 to 14.3 (μmol/L/mmol Cr; median, IQR) to 12.9, 9.1 to 17.7 post exercise (p = 0.0003, Mann Whitney U test). Of the 20 participants, eight participants had a rise of the NAG/Cr ratio post exercise whereas 12 did not. Participants with a rise in the NAG/Cr ratio post exercise had a greater ability to increase endothelial reactivity (%; median, IQR; 2.56, 0.1 to 3.7) cf. (0.1, -4.8 to 0.9, p = 0.03); they also walked further (metres; median, IQR; 415, 208 to 908) cf. (170, 100 to 315, p = 0.04), had a lower pre-exercise H2O2 (median, IQR; 1.9, 1.4 to 2.3 cf. 2.7, 2.1 to 3.3; p = 0.04) and a greater rise in H2O2 post exercise (18.8, -1.5 to 129.7 cf., -7.7, -13.9 to -2.0, p = 0.04). The mechanism by which the phenotypically distinct sub-group of patients with intermittent claudication who experience a NAG/Cr rise involves complex interactions between systemic oxidative stress and endothelial function. Implications on cardiovascular risk in this group requires further investigation.

Effects of oral N-acetylcysteine on walking capacity, leg reactive hyperemia, and inflammatory and angiogenic mediators in patients with intermittent claudication

Increased oxidative stress and inflammation contribute to impaired walking capacity and endothelial dysfunction in patients with intermittent claudication (IC). The goal of the study was to determine the effects of oral treatment with the antioxidant N-acetylcysteine (NAC) on walking capacity, leg postocclusive reactive hyperemia, circulating levels of inflammatory mediators, and whole blood expression of angiogenic mediators in patients with IC. Following a double-blinded randomized crossover design, 10 patients with IC received NAC (1,800 mg/day for 4 days plus 2,700 mg before the experimental session) and placebo (PLA) before undergoing a graded treadmill exercise test. Leg postocclusive reactive hyperemia was assessed before and after the test. Blood samples were taken before and after NAC or PLA ingestions and 5 and 30 min after the exercise test for the analysis of circulating inflammatory and angiogenic markers. Although NAC increased the plasma ratio of reduced to oxidized glutathione, there were no differences between experimental sessions for walking tolerance and postocclusive reactive hyperemia. Plasma concentrations of soluble vascular cell adhesion protein-1, monocyte chemotactic protein-1, and endothelin-1 increased similarly following maximal exercise after PLA and NAC (P < 0.001). Whole blood expression of pro-angiogenic microRNA-126 increased after maximal exercise in the PLA session, but treatment with NAC prevented this response. Similarly, exercise-induced changes in whole blood expression of VEGF, endothelial nitric oxide synthase and phosphatidylinositol 3-kinase R2 were blunted after NAC. In conclusion, oral NAC does not increase walking tolerance or leg blood flow in patients with IC. In addition, oral NAC prevents maximal exercise-induced increase in the expression of circulating microRNA-126 and other angiogenic mediators in patients with IC.

Protein concentration and mitochondrial content in the gastrocnemius predicts mortality rates in patients with peripheral arterial disease

OBJECTIVE

This study evaluated the hypothesis that protein concentration and mitochondrial content in gastrocnemius biopsies from patients with peripheral arterial disease (PAD) predict mortality rates.

BACKGROUND

PAD patients experience advancing myopathy characterized by mitochondrial dysfunction, myofiber degradation, and fibrosis in their ischemic legs, along with increased mortality rates.

METHODS

Samples from the gastrocnemius of PAD patients were used for all analyses. Protein concentration was normalized to muscle wet weight, and citrate synthase activity (standard measure of mitochondrial content in cells) was normalized to muscle wet weight and protein concentration. Protein and citrate synthase data were grouped into tertiles and 5-year, all-cause mortality for each tertile was determined with Kaplan-Meier curves and compared by the modified Peto-Peto test. A Cox-regression model for each variable controlled for the effects of clinical characteristics.

RESULTS

Of the 187 study participants, 46 died during a mean follow-up of 23.0 months. Five-year mortality rate was highest for patients in the lowest tertile of protein concentration. Mortality was lowest for patients in the middle tertile of citrate synthase activity when normalized to either muscle wet weight or protein concentration. The mortality hazard ratios (HRs) from the Cox analysis were statistically significant for protein concentration normalized to muscle wet weight (lowest vs middle tertile; HR = 2.93; P = 0.008) and citrate synthase normalized to protein concentration (lowest vs middle tertile; HR = 4.68; P = 0.003; and lowest vs highest tertile; HR = 2.36; P = 0.027).

CONCLUSIONS

Survival analysis of a contemporaneous population of PAD patients identifies protein and mitochondrial content of their gastrocnemius as predictors of mortality rate.

Physiology in medicine: peripheral arterial disease

Peripheral arterial disease (PAD) is an atherosclerotic condition that can provoke symptoms of leg pain ("intermittent claudication") during exercise. Because PAD is often observed with comorbid conditions such hypertension, dyslipidemia, diabetes, cigarette smoking, and/or physical inactivity, the pathophysiology of PAD is certainly complex and involves multiple organ systems. Patients with PAD are at high risk for myocardial infarction, stroke, and all-cause mortality. For this reason, a better physiological understanding of the pathogenesis and treatment options for PAD patients is necessary and forms the basis of this Physiology in Medicine review.

Mitochondriopathy of peripheral arterial disease

The signs and symptoms of peripheral arterial occlusive disease (PAD), including claudication, rest pain, and tissue loss, are consequences of compromised bioenergetics and oxidative tissue injury within the affected lower extremities. Compromised bioenergetics is the result of a combination of low blood flow through diseased arteries and diminished adenosine triphosphate production by dysfunctional mitochondria. The tissue injury appears to be secondary to increased production of reactive oxygen species by dysfunctional mitochondria and by inflammation, in association with ischemia and ischemia/reperfusion. In this review, we present the current histomorphologic, physiologic, and biochemical evidence defining the nature of this mitochondriopathy and discuss its contribution to the pathogenesis and clinical manifestations of PAD.

The myopathy of peripheral arterial occlusive disease: Part 2. Oxidative stress, neuropathy, and shift in muscle fiber type

In recent years, an increasing number of studies have demonstrated that a myopathy is present, contributes, and, to a certain extent, determines the pathogenesis of peripheral arterial occlusive disease. These works provide evidence that a state of repetitive cycles of exercise-induced ischemia followed by reperfusion at rest operates in patients with peripheral arterial occlusive disease and mediates a large number of structural and metabolic changes in the muscle, resulting in reduced strength and function. The key players in this process appear to be defective mitochondria that, through multilevel failure in their roles as energy, oxygen radical species, and apoptosis regulators, produce and sustain a progressive decline in muscle performance. In this 2-part review, the currently available evidence that characterizes the nature and mechanisms responsible for this myopathy is highlighted. In part 1, the functional and histomorphological characteristics of the myopathy were reviewed, and the main focus was on the biochemistry and bioenergetics of its mitochondriopathy. In part 2, accumulating evidence that oxidative stress related to ischemia reperfusion is probably the major operating mechanism of peripheral arterial occlusive disease myopathy is reviewed. Important new findings of a possible neuropathy and a shift in muscle fiber type are also reviewed. Learning more about these mechanisms will enhance our understanding of the degree to which they are preventable and treatable.

Changes in inflammatory biomarkers following one-year of moderate resistance training in overweight women

BACKGROUND

Overweight individuals commonly demonstrate elevated levels of inflammatory and cell adhesion molecules. Elevated levels of inflammation and adhesion have been implicated in the pathogenesis of cardiovascular disease. Aerobic exercise has been shown to be effective in altering specific biomarkers of inflammation and cell adhesion; however, little is known regarding the effects of resistance training (RT) on these biomarkers. This study examined the effects of 1 year of moderate-intensity RT on biomarkers of inflammation and adhesion in healthy, overweight women.

METHODS AND RESULTS

Participants included 28 (12 control, 16 RT) overweight (body mass index>or=25 kg/m2) women, aged 25-44 years, studied before and after 1 year of RT. C-reactive protein (CRP), interleukin-6 (IL-6), adiponectin, intracellular adhesion molecule-1, vascular cell adhesion molecule-1 and E-selectin were measured by standard enzyme-linked immunosorbent assays. Body composition, blood pressure, fasting blood lipids, glucose and insulin also were assessed. There were no significant changes in blood pressure, fasting blood lipids, glucose or insulin levels in either group after 1 year. There was also no change in body mass or fat mass in either group; however, there was a significant increase in lean body mass (P<0.05) in the RT group. Both CRP (P<0.01) and adiponectin (P<0.01) demonstrated significant improvements in the RT group, with no change in IL-6. Conversely, there were no associated changes in the biomarkers of cell adhesion in either group.

CONCLUSIONS

This study demonstrates that moderate-intensity RT significantly results in modest improvements of inflammatory markers without affecting cell adhesion molecules in overweight women.

The constitutive procoagulant and hypofibrinolytic state in patients with intermittent claudication due to infrainguinal disease significantly improves with percutaneous transluminal balloon angioplasty

BACKGROUND

Patients with intermittent lower limb claudication (IC) exhibit a prothrombotic diathesis that is acutely exacerbated by exercise. This may occur because of ischemia/reperfusion injury within the leg muscles during walking and may contribute to the increased risk of thrombotic vascular events in this group of patients. This randomized study compared the effect of lower limb revascularization by percutaneous transluminal balloon angioplasty (PTA), supervised exercise, and best medical therapy (BMT) alone on this prothrombotic state.

METHODS

Twenty-three patients (16 men and 7 women; median age, 67 years; range, 57-77 years) with IC due to infrainguinal disease were randomized to receive BMT alone (n = 7), BMT plus PTA (n = 9), or BMT plus supervised exercise (n = 7) as part of the Health Technology Assessment-funded EXercise vs Angioplasty in Claudication Trial (EXACT). Patients were assessed at baseline and at 3 and 6 months. Thrombin-antithrombin complex (TAT) was determined as a marker of thrombin generation, and plasminogen activator inhibitor (PAI) antigen was determined as a marker of fibrinolysis. Increased TAT indicates a procoagulant state, and increased PAI antigen indicates a hypofibrinolytic state.

RESULTS

At 6 months, subjects randomized to BMT plus PTA demonstrated a significant improvement in ankle-brachial pressure index (P = .013) and maximal walking distance (P = .008), a significant decline in resting thrombin generation (median [interquartile range] TAT, 6.4 microg/L [2.7-13.5 microg/L] to 1.5 microg/L [0.3-2.9 microg/L]; P = .038), and an improvement in resting fibrinolysis (median [interquartile range] PAI-1, 10.0 ng/mL [1.0-20.5 ng/mL] to 1.0 ng/mL [1.0-14.8 ng/mL]; P = .043). There was no significant change in any of these parameters in patients randomized to BMT plus supervised exercise or to BMT alone.

CONCLUSIONS

The addition of lower limb revascularization by PTA to BMT in patients with IC due to infra-inguinal disease results in a medium-term improvement in the resting procoagulant and hypofibrinolytic state. This may translate into a reduction in morbidity and mortality from thrombotic vascular events in this group of patients.

Biochemical evaluation of antioxidant function after a controlled optimum physical exercise among adolescents

Sensible physical exercise is shown to prevent certain neurovascular problems. However, in recent times, non-traumatic sudden death in young athletes has been observed and the incidence level is always very disturbing, because of the spontaneous nature of the occurrence. It most commonly occurs fivefold more in male than female athletes. Although it is believed that congenital cardiovascular disease is the leading cause of non-traumatic sudden athletic death, however, sudden physical alteration in the biochemical composition of the body system may, at least in part, play an important role. The role of antioxidants in the general maintenance of homeostasis has already been established. In this study, total antioxidant function in athletes subjected to controlled physical exercise was evaluated to determine the extent to which intensive physical exercise could alter the health conditions if adequate actions are not taken to adjust the biochemistry of the body system. Ten male field-track athletes were exercised using a fixed workload treadmill test. Blood samples were drawn before and after the exercise. The subjects exercised almost to their maximum running distance at a higher "fatigue" workload for a maximum of 20 min each day for five days. The lymphocytes' total antioxidant function was measured by addition of a peroxide (oxidative stress) to complete the medium. Lymphocyte growth response with peroxide was reported as a percentile of growth responses from a reference range of apparently healthy individuals. Values below the 25th percentile indicate a deficient antioxidant function. The results showed that although vitamin B3, B6, and B12 requirements were normal, there was a consistent low value in the total percentile of vitamins B1 (<79%), B2 (<54%), folate (<33%, and biotin (<70%). There was a dramatic decrease in the mean values of antioxidant function (38.1%) in all the subjects as opposed to the reference range of <75%. Overall reduction antioxidant function indicates decreased ability to resist oxidative stress, or an increased oxidant load, suggesting increased antioxidant utilization and/or cellular "tear and wear" scenario. It is therefore suggested that after intensive physical exercise, antioxidant functions should be monitored and supplemented whenever necessary to maintain the integrity of the cellular function.

Chronic Transcutaneous Electrical Stimulation of Calf Muscles Improves Functional Capacity without Inducing Systemic Inflammation in Claudicants

OBJECTIVES

To assess whether electrical stimulation of ischaemic calf muscles in claudicants causes a systemic inflammatory response and to evaluate effects of its chronic application on muscle function and walking ability.

DESIGN

Prospective randomised controlled trial of calf muscle stimulation.

MATERIALS AND METHODS

Stable claudicants were randomised to receive either active chronic low frequency (6 Hz) motor stimulation (n=15) or, as a control treatment, submotor transcutaneous electrical nerve (TENS) stimulation (n=15) of calf muscles in one leg, 3 x 20 min per day for four weeks. Leucocyte activation was quantified by changes in cell morphology, vascular permeability by urinary albumin:creatinine ratio (ACR), calf muscle function by isometric twitch contractions and walking ability by treadmill performance pre- and post-intervention.

RESULTS

Acute active muscle stimulation activated leucocytes less (28% increase) than a standard treadmill test (81% increase) and did not increase ACR. Chronic calf muscle stimulation significantly increased pain-free walking distance by 35 m (95% CI 17, 52, P<0.001) and maximum walking distance by 39 m (95% CI 7, 70, P<0.05) while control treatment had no effect. Active stimulation prevented fatigue of calf muscles during isometric electrically evoked contractions by abolishing the slowing of relaxation that was responsible for loss of force.

CONCLUSIONS

Chronic electrical muscle stimulation is an effective treatment for alleviating intermittent claudication which, by targeted activation of a small muscle mass, does not engender a significant systemic inflammatory response.

Exercise in claudicants is accompanied by excessive thrombin generation

BACKGROUND

exercise in IC leads to ischaemia-reperfusion injury of leg muscles and a systemic inflammatory response, but the effect of on coagulation is unknown.

OBJECTIVE

to compare the effect of exercise on thrombin formation and fibrin turnover in patients with IC (n = 10), and age and sex matched smokers ([S] n = 5) and non-smokers ([NS] n = 5) without peripheral vascular disease.

METHODS

blood was taken from subjects 60 and 30 min before, and 1, 5, 20, 40, 60 and 120 min after, treadmill exercise. Markers of thrombin generation (thrombin-antithrombin complexes [TAT] and prothrombin fragments 1 + 2 [PF1 + 2]) and fibrin turnover (D-dimer and fibrin degradation products [FbDP]) were assayed at each time point.

RESULTS

following exercise, thrombin generation was significantly greater in the claudicant group compared to the control groups (Area Under Curve [AUC] post exercise IC vs S vs NS; TAT 3960 vs 1623 vs 1476 vs = 0.007 Kruskal-Wallis [KW]; PF1 + 2 163 vs 107 vs 123 p = 0.024 KW). Pre and post-exercise, fibrin turnover in claudicants was similar to smoking controls, but higher than non-smoking controls. (AUC post exercise IC vs NS; D-dimer 6340 vs 2754 p = 0.055 Mann-Whitney U[MW]; FbDP 45113 vs 21511 p = 0.009 MW).

CONCLUSION

when compared to non-claudicants, exercise in IC is associated with excessive production of thrombin. Despite this, claudicants have a similar level of fibrin turnover suggesting a possible defect in fibrinolysis. This prothrombotic state may contribute to the excess thrombotic morbidity and mortality suffered by claudicants.

What constitutes best medical therapy for peripheral arterial disease?

Peripheral arterial disease (PAD) is associated with a high morbidity and mortality, largely from coronary and cerebrovascular disease, which often overshadows the PAD itself. Best Medical Therapy (BMT), comprising smoking cessation, antiplatelet agent use, cholesterol reduction, exercise therapy, and the diagnosis and treatment of hypertension and diabetes mellitus; is evidenced based and can result in significant reductions in cardiovascular risk, as well as some improvement in PAD. Previous data have largely been restricted to patients with coronary artery disease, and their relevance to PAD has been extrapolated. However, data are now starting to become available, such as the Heart Protection Study, with data specific to PAD patients. This article reviews the data regarding the use of BMT in patients with PAD, and based on this, makes recommendations for the use of BMT in this group of patients.

Exercise training reduces the acute inflammatory response associated with claudication

BACKGROUND

recent research has shown that episodes of claudication may be associated with a systemic inflammatory response that causes injury to the vascular endothelium. As claudicants are often directed to undertake regular walking exercises there has been a concern that this may accelerate endothelial injury.

AIMS

the aim of our study was to assess the baseline markers of ischaemia-reperfusion injury (IRI) in claudicants and controls after acute treadmill exercise and to then examine the effect of a 3 month supervised exercise-training programme, on these markers, in the claudicant group.

METHODS

forty-six claudicants and 22 age-matched controls undertook acute treadmill exercise. Neutrophil activation, degranulation, free radical damage and antioxidants were measured (by flow cytometry, ELISA, and chemiluminescence) at rest and at 5, 30 and 60 min post-exercise. Claudicants were then recruited into an intensive 3 month supervised exercise programme (SEP) after which the same parameters of IRI were reassessed at different time points, at 3 and 6 months.

RESULTS

resting markers of IRI were similar in both groups. Exercise had no effect on the control group. Immediately after exercise, claudicants developed significant neutrophil activation and degranulation with free radical damage. This effect decreased sequentially after 3 months of exercise training.

CONCLUSION

this study for the first time demonstrates that the exercise training of claudicants is beneficial, not only in terms of improving their walking distance, but also by decreasing the injurious effects of IRI that occur during claudication. Exercise training should be an essential part of the medical management of the majority of claudicants.

The value of toe pulse waves in determination of risks for limb amputation and death in patients with peripheral arterial disease and skin ulcers or gangrene

OBJECTIVES

The purpose of this study was to determine whether the presence of low amplitude of pulse waves recorded from the toes is related to the risk of subsequent amputation and death in patients with skin ulcers or gangrene and peripheral arterial disease, and how the risk of low wave amplitude relates to the risk associated with low peripheral pressures.

METHODS

A total of 309 patients with 346 limbs with skin lesions and arterial disease referred to the vascular laboratory were followed up for an average of 5 years (range, 1-8 years). Measurements were carried out to obtain ankle and toe pressures, pressure indices, and toe pulse wave amplitude. These variables were related to the risks of major amputation and total and cardiovascular death by means of the Cox proportional hazards model.

RESULTS

Low toe pulse wave amplitude (< or = 4 mm) was associated with increased risk of amputation (relative risks 4.20 in all limbs and 2.63 in those with toe pressure < or = 30 mm Hg; P <.01). Wave amplitude remained significantly associated with increased risk of amputation after controlling for each pressure variable (P <.01). Low pulse wave amplitude and toe/brachial index were associated with increased risks of both total and cardiovascular death in all patients (relative risks ranged from 1.43-1.73; P <.05) and in those with toe pressure of 30 mm Hg or less (relative risks 1.56-1.90; P <.05).

CONCLUSIONS

Low toe pulse wave amplitude is related significantly to increased risks of amputation and death in patients with skin lesions and arterial disease. The presence of low wave amplitude provides significant information in addition to peripheral pressures with respect to the risk of amputation.

Antioxidants reduce oxidative stress in claudicants

BACKGROUND

Low-grade ischemia-reperfusion in claudicants leads to damage of local tissues and remote organs. Since this damage is partly caused by oxygen-derived free radicals (ODFR), scavenging these ODFR could reduce the local and remote injury.

METHODS

Using a new method by which a free radical reaction product (ortho-APOH) of the exogenous marker antipyrine is measured to quantify the oxidative stress, 16 stable claudicants performed a standard walking test before and after administration of vitamin E (200 mg) and vitamin C (500 mg) daily for 4 weeks.

FINDINGS

Ortho-APOH was significantly increased during the reperfusion period (P = 0.026) before administration of the vitamins. After 4 weeks of vitamin supplementation no rise was found in the reperfusion period. Malondialdehyde showed no changes in either group.

INTERPRETATION

These findings indicate that administering extra antioxidants to claudicants reduces oxidative stress in these patients. This may also have an effect on the remote ischemia-reperfusion damage and reduce cardiovascular morbidity in this group.

Exercise therapy or angioplasty? A summation analysis

OBJECTIVES

To compare the outcome of exercise therapy or angioplasty for the treatment of patients with intermittent claudication.

DESIGN

A summation analysis.

METHODS

A search using MEDLINE and PUBMED between 1966 and April 1999 followed by a review of the manuscripts yielded 54 studies involving angioplasty and 27 studies involving exercise therapy for intermittent claudication. Studies were only included (12 angioplasty and nine exercise series) when results were available for patients with intermittent claudication alone, and when outcome was assessed in terms of symptoms at a minimum of 6 months.

RESULTS

The total number of claudicants undergoing exercise therapy was 294 patients, with a mean symptomatic success rate of 38. 4% and a mean improvement in maximum walking distance of 189.7% at 6 months. The total number of claudicants undergoing angioplasty was 2071, with a mean overall symptomatic success rate of 76.6%. The mean overall complication rate was 9% and mean major complication rate was 2.7% for the angioplasty studies.

CONCLUSION

Although the result demonstrates an advantage of angioplasty over exercise therapy at 6 months, there is a small risk of major complications. However, comparison of studies was impaired due to disparity in patient numbers, limited follow-up time and lack of uniformity in outcome assessment. In order to achieve a valid comparison of these therapies in a future randomised study, a validated disease-specific instrument for the assessment of symptomatic outcome for claudicants is required.

Dietary fats and immune status in athletes: clinical implications

Athletes are competitive, train at very high levels with inadequate rest, consume too few calories, avoid fats, and may be at increased risk of infections. The immune system is sensitive to both fat intake and intense exercise, suggesting that athletes may have suppressed immune function. It has been reported that many athletes consume about 25% fewer calories than the estimated expenditure, leading to low intakes of some essential micronutrients and fats. Acute exercise has been shown to increase inflammatory and decrease antiinflammatory immune factors and may increase oxidant stress. Chronic exercise appears to improve immune competence. Lipids are powerful mediators of the immune system, and they may modulate the immunosuppressive effects of strenuous exercise. Studies have shown that a low-fat high-carbohydrate diet (15% fat, 65% CHO, 20% protein of total calories), typically eaten by athletes, increases inflammatory and decreases antiinflammatory immune factors, depresses antioxidants, and negatively affects blood lipoprotein ratios. Increasing total caloric intake by 25% to match energy expenditure and the dietary fat intake to 32% in athletes appears to reverse the negative effects on immune function and lipoprotein levels reported on a low-fat diet. Increasing the dietary fat intake of athletes to 42%, while maintaining caloric intake equal to expenditure, does not negatively affect immune competency or blood lipoproteins, whereas it improves endurance exercise performance at 60-80% of VO2max in cyclists, soldiers, and runners. There is no evidence that higher fat intakes (up to 42% of total calories), in calorically balanced diets, increase the risk of cancer, but studies are needed to determine whether the beneficial effects of higher fat diets in athletes reduce their rate of infections.