Moderate Exercise Allows for shorter Recovery Time in Critical Limb Ischemia

A 6-minute Limb Function Assessment for Therapeutic Testing in Experimental Peripheral Artery Disease Models

Background

The translation of promising therapies from pre-clinical models of hindlimb ischemia (HLI) to patients with peripheral artery disease (PAD) has been inadequate. While this failure is multifactorial, primary outcome measures in preclinical HLI models and clinical trials involving patients with PAD are not aligned well. For example, laser Doppler perfusion recovery measured under resting conditions is the most used outcome in HLI studies, whereas clinical trials involving patients with PAD primarily assess walking performance. Here, we sought to develop a 6-min limb function test for preclinical HLI models that assess muscular performance and hemodynamics congruently.

Methods

We developed an in situ 6-min limb function test that involves repeated isotonic (shortening) contractions performed against a submaximal load. Continuous measurement of muscle blood flow was performed using laser Doppler flowmetry. Quantification of muscle power, work, and perfusion are obtained across the test. To assess the efficacy of this test, we performed HLI via femoral artery ligation on several mouse strains: C57BL6J, BALBc/J, and MCK-PGC1α (muscle-specific overexpression of PGC1α). Additional experiments were performed using an exercise intervention (voluntary wheel running) following HLI.

Results

The 6-min limb function test was successful at detecting differences in limb function of C57BL6/J and BALBc/J mice subjected to HLI with effect sizes superior to laser Doppler perfusion recovery. C57BL6/J mice randomized to exercise therapy following HLI had smaller decline in muscle power, greater hyperemia, and performed more work across the 6-min limb function test compared to non-exercise controls with HLI. Mice with muscle-specific overexpression of PGC1α had no differences in perfusion recovery in resting conditions, but exhibited greater capillary density, increased muscle mass and absolute force levels, and performed more work across the 6-min limb function test compared to their wildtype littermates without the transgene.

Conclusion

These results demonstrate the efficacy of the 6-min limb function test to detect differences in the response to HLI across several interventions including where traditional perfusion recovery, capillary density, and muscle strength measures were unable to detect therapeutic differences.

Comparison of complete multi-level vs. iliac-only revascularization for concomitant iliac and superficial femoral artery occlusive disease

Objective

The aim of this study is to compare the efficacy and safety of complete multi-level vs. iliac-only revascularization for the treatment of concomitant iliac and superficial femoral artery (SFA) occlusive disease.

Methods

A total of 139 consecutive adult patients with severe stenosis and occlusive iliac and SFA disease with Rutherford categories 2-5 underwent multi-level (n = 71) and iliac-only (n = 68) revascularization at the Department of Intervention Vascular Surgery, Peking University Third Hospital, and Aerospace Center Hospital, between March 2015 and June 2017. Improvement in Rutherford class, perioperative major adverse events, the length of stay, survival rate, and limb salvage rate were assessed. The neutrophil-lymphocyte ratio and platelet-lymphocyte ratio were compared between the two groups.

Results

At 48 months, improvement in the Rutherford category was observed in the two groups with no significant difference (P = 0.809). Additionally, the two groups were similar concerning the primary patency (84.0% vs. 79.1%, P = 0.717) and limb salvage rate (93.1% vs. 91.3%, P = 0.781). A higher proportion of the perioperative major adverse events (33.8% vs. 27.9%, P = 0.455), the all-cause mortality (11.3% vs. 8.8%, P = 0.632), and the average length of hospital stay [7.0 (6.0, 11.0) vs. 7.0 (5.0, 8.0), P = 0.037] were seen in the multi-level group compared with the iliac-only group.

Conclusion

For concomitant iliac and superficial femoral artery occlusive disease, iliac-only revascularization has favorable efficacy and safety outcomes compared with complete multi-level revascularization in selected patients with patent profunda femoris artery and at least one healthy outflow tract of the infrapopliteal artery.

Systematic review and meta-analyses of studies analysing instructions to authors from 1987 to 2017

To gain insight into changes of scholarly journals' recommendations, we conducted a systematic review of studies that analysed journals' Instructions to Authors (ItAs). We summarised results of 153 studies, and meta-analysed how often ItAs addressed: 1) authorship, 2) conflicts of interest, 3) data sharing, 4) ethics approval, 5) funding disclosure, and 6) International Committee of Medical Journal Editors' Uniform Requirements for Manuscripts. For each topic we found large between-study heterogeneity. Here, we show six factors that explained most of that heterogeneity: 1) time (addressing of topics generally increased over time), 2) country (large differences found between countries), 3) database indexation (large differences found between databases), 4) impact factor (topics were more often addressed in highest than in lowest impact factor journals), 5) discipline (topics were more often addressed in Health Sciences than in other disciplines), and 6) sub-discipline (topics were more often addressed in general than in sub-disciplinary journals).

Potentially undiagnosed cognitive impairment in patients with peripheral arterial disease: A systematic review of the literature

INTRODUCTION

It is purported that patients with peripheral arterial disease (PAD) may have impaired cognitive function due to concomitant cerebrovascular disease. Such disease may be clinically unrecognized but can impact on a patient's recovery and prognosis. The purpose of this systematic review was to interrogate the body of published evidence on undiagnosed cognitive impairment in PAD patients.

METHODS

A search strategy encompassing MEDLINE, Scopus, and the Cochrane database was developed to identify peer-reviewed articles examining rates of undiagnosed cognitive impairment in patients with PAD. The following search terms were used: 'PAD'; 'PVD'; 'dementia'; 'peripheral arterial disease'; 'peripheral vascular disease'; 'cognitive impairment'; 'alzheimer's disease' and 'cogniti∗'. Our primary outcome was the incidence of previously undiagnosed cognitive impairment in patients with PAD.

RESULTS

The initial search yielded 1492 titles. After removal of duplicates, 961 abstracts were screened to ascertain if they were eligible for inclusion. Abstract review yielded 62 full texts for further evaluation. Eight case-control studies consisting of 1161 patients were included. Analysis of these studies revealed that PAD patients performed significantly worse than controls on a variety of neuropsychological measures.

CONCLUSION

Our review indicated that PAD patients are more likely to suffer with undiagnosed cognitive impairment than healthy controls.

Avoiding revascularization strategy versus revascularization with drug-coated balloon for the treatment of superficial femoral artery occlusive disease

OBJECTIVE

The aim of this study was to compare the efficacy, safety and treatment costs of superficial femoral artery revascularization (SFA) with drug-coated balloon(DCB) versus avoiding revascularization strategy for the treatment of symptomatic SFA disease.

METHODS

This retrospective single-center study reviewed 96 patients (113 limbs) with severe stenosis and occlusive SFA disease. All patients underwent either DCB(Group 1: n ​= ​55 limbs) or nonrevascularization (Group 2: n ​= ​58 limbs) between March 2015 and June 2019. The improvement of Rutherford class, walking impairment questionnaire score(WIQ), target limb reintervention, perioperative major adverse events, the catheterization laboratory cost and length of hospital stay were compared. The limb salvage and survival rates were calculated using the Kaplan-Meier method. Univariate and multivariate logistic regression analysis were performed to assess the association between factors and the improvement of Rutherford category at 12 months.

RESULTS

The median follow-up time of Groups 1 and 2 was 17 and 33 months, respectively. At 12 months, the Rutherford category significantly decreased in both groups (P ​< ​0.001), with no significant difference (79.7% vs. 64.3%, P ​= ​0.074). Furthermore, multivariate analysis showed that the selected therapeutic method was not an influential factor for the improvement of Rutherford class at 12 months. The WIQ overall score as well as three subscales scores (distance, speed and stair-climbing), the survival rate, limb salvage rate and the length of stay between the two groups were comparable. The perioperative adverse events rate and catheterization laboratory cost in Group 2 was significantly lower compared to Group 1 [(34253.69 ​± ​28172.87) yuan vs. (56936.76 ​± ​41278.36) yuan, P ​= ​0.001].

CONCLUSIONS

This study suggests that avoiding superficial femoral artery revascularization strategy has favorable efficacy and safety outcomes compared to combining revascularization with DCB in selected patients.

The cold truth: the role of cryotherapy in the treatment of injury and recovery from exercise

Cryotherapy is utilized as a physical intervention in the treatment of injury and exercise recovery. Traditionally, ice is used in the treatment of musculoskeletal injury while cold water immersion or whole-body cryotherapy is used for recovery from exercise. In humans, the primary benefit of traditional cryotherapy is reduced pain following injury or soreness following exercise. Cryotherapy-induced reductions in metabolism, inflammation, and tissue damage have been demonstrated in animal models of muscle injury; however, comparable evidence in humans is lacking. This absence is likely due to the inadequate duration of application of traditional cryotherapy modalities. Traditional cryotherapy application must be repeated to overcome this limitation. Recently, the novel application of cooling with 15 °C phase change material (PCM), has been administered for 3-6 h with success following exercise. Although evidence suggests that chronic use of cryotherapy during resistance training blunts the anabolic training effect, recovery using PCM does not compromise acute adaptation. Therefore, following exercise, cryotherapy is indicated when rapid recovery is required between exercise bouts, as opposed to after routine training. Ultimately, the effectiveness of cryotherapy as a recovery modality is dependent upon its ability to maintain a reduction in muscle temperature and on the timing of treatment with respect to when the injury occurred, or the exercise ceased. Therefore, to limit the proliferation of secondary tissue damage that occurs in the hours after an injury or a strenuous exercise bout, it is imperative that cryotherapy be applied in abundance within the first few hours of structural damage.

Exercise enhances mitochondrial fission and mitophagy to improve myopathy following critical limb ischemia in elderly mice via the PGC1a/FNDC5/irisin pathway

Background

Elderly populations are susceptible to critical limb ischemia (CLI), but conventional treatments cannot significantly decrease amputation and mortality. Although exercise is an effective “non-pharmacological medicine” targeting mitochondria to improve skeletal muscle function, few studies have focused on the application of exercise in CLI.

Methods

Elderly male C57BL/6 mice (14 months old) were used to establish a CLI model to assess the effect of exercise on perfusion, performance recovery, apoptosis, mitochondrial function, and mitochondrial turnover in gastrocnemius muscle. The potential underlying mechanism mediated by PGC1a/FNDC5/irisin was confirmed in hypoxic and nutrient-deprived myotubes undergoing electrical pulse stimuli (EPS).

Results

Exercise significantly accelerated the perfusion recovery and exercise performance in ischemic limbs following CLI. Exercise improved the mitochondrial membrane potential and total ATP production and decreased apoptosis in the ischemic limbs. Exercise increased the formation of mitochondrial derived vesicle-like structures and decreased the mitochondrial length in the ischemic limbs, accompanied by upregulated PGC1a/FNDC5/irisin expression. In vitro, PGC1a/FNDC5/irisin downregulation decreased EPS-elevated PINK1, Parkin, DRP1, and LC3B mRNA levels. The irisin levels in the culture medium were correlated with the expression of mitochondrial fission and mitophagy markers in myotubes.

Conclusion

Exercise enhanced mitochondrial fission and selective autophagy to promote the recovery of myopathy after CLI in elderly mice through the PGC1a/FNDC5/irisin pathway, supporting the efficacy of exercise therapy in elderly individuals with CLI and demonstrating the potential of targeting PGC1a/FNDC5/irisin as a new strategy for the treatment of CLI.

Impact of aerobic exercise type on blood flow, muscle energy metabolism, and mitochondrial biogenesis in experimental lower extremity artery disease

Exercise training (ET) is recommended for lower extremity artery disease (LEAD) management. However, there is still little information on the hemodynamic and metabolic adaptations by skeletal muscle with ET. We examined whether hindlimb perfusion/vascularization and muscle energy metabolism are altered differently by three types of aerobic ET. ApoE^−/− mice with LEAD were assigned to one of four groups for 4 weeks: sedentary (SED), forced treadmill running (FTR), voluntary wheel running (VWR), or forced swimming (FS). Voluntary exercise capacity was improved and equally as efficient with FTR and VWR, but remained unchanged with FS. Neither ischemic hindlimb perfusion and oxygenation, nor arteriolar density and mRNA expression of arteriogenic-related genes differed between groups. ¹⁸FDG PET imaging revealed no difference in the steady-state levels of phosphorylated ¹⁸FDG in ischemic and non-ischemic hindlimb muscle between groups, nor was glycogen content or mRNA and protein expression of glucose metabolism-related genes in ischemic muscle modified. mRNA (but not protein) expression of lipid metabolism-related genes was upregulated across all exercise groups, particularly by non-ischemic muscle. Markers of mitochondrial content (mitochondrial DNA content and citrate synthase activity) as well as mRNA expression of mitochondrial biogenesis-related genes in muscle were not increased with ET. Contrary to FTR and VWR, swimming was ineffective in improving voluntary exercise capacity. The underlying hindlimb hemodynamics or muscle energy metabolism are unable to explain the benefits of running exercise.

Sarcopenia and peripheral arterial disease: a systematic review

BACKGROUND

Patients with lower extremity peripheral arterial disease (PAD) and sarcopenia are a population at risk requiring specific and targeted care. The aim of this review is to gather all relevant studies associating sarcopenia and PAD and to identify the underlying pathophysiological mechanisms as well as potential therapeutic strategies to improve skeletal muscle function.

METHODS

A systematic review was carried out following the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA).

RESULTS

Data extraction allowed the evaluation of 140 publications; 87 met the inclusion criteria; of which 79 were included in the final review, reporting sufficient data for epidemiological and diagnostic criteria, mechanical analysis, and therapeutic approaches. Epidemiological analysis and diagnostic criteria were based on 18 studies following 2362 PAD patients [31.39% (SD 7.61) women], aged 72.42 (SD 2.84); sarcopenia was present in 34.63% (SD 12.86) of the patients. Mechanical and pathway analysis were based on five animal studies and 29 clinical reports, showing significantly altered muscle strength and function in 1352 PAD patients [26.49% (SD 17.32) women], aged 67.67 (SD 5.14) years; impaired muscle histology in 192 PAD patients (9.2% (SD 11.22) women), aged 64.3 (SD 0.99) years; +58.63% (SD 25.48) of oxidative stress in 69 PAD patients [16.96% (SD 8.10) women], aged 63.17 (SD 1.43) years; mitochondriopathy in 153 PAD patients [29.39% (SD 28.27) women], aged 63.50 (SD 1.83) years; +15.58% (SD 7.41) of inflammation in 900 PAD patients [40.77% (SD 3.71) women], aged 74.88 (SD 2.76) years; and altered signalling pathways in 51 PAD patients [34.45% (SD 32.23) women], aged 72.25 (SD 5.25) years. Therapeutic approaches analysis was based on seven animal studies and 21 clinical reports. In total, 884 patients followed an exercise therapy, and 18 received an angiogenesis treatment; 30.84% (SD 17.74) were women. Mean ages of patients studied were 66.85 (SD 3.96).

CONCLUSIONS

Sarcopenia and lower extremity PAD have musculoskeletal consequences that directly impair patients' quality of life and prognosis. Although PAD is primarily a vascular disease, all etiological factors of sarcopenia identified so far are present in PAD. Indeed, both sarcopenia and PAD are accompanied by oxidative stress, skeletal muscle mitochondrial impairments, inflammation, inhibition of specific pathways regulating muscle synthesis or protection (i.e. IGF-1, RISK, and SAFE), and activation of molecules associated with muscle degradation. To date, besides revascularization, the best therapeutic strategy includes exercise, but approaches targeting the underlying mechanisms still deserve further studies.

The Rise of Mitochondria in Peripheral Arterial Disease Physiopathology: Experimental and Clinical Data

Peripheral arterial disease (PAD) is a frequent and serious condition, potentially life-threatening and leading to lower-limb amputation. Its pathophysiology is generally related to ischemia-reperfusion cycles, secondary to reduction or interruption of the arterial blood flow followed by reperfusion episodes that are necessary but also—per se—deleterious. Skeletal muscles alterations significantly participate in PAD injuries, and interestingly, muscle mitochondrial dysfunctions have been demonstrated to be key events and to have a prognosis value. Decreased oxidative capacity due to mitochondrial respiratory chain impairment is associated with increased release of reactive oxygen species and reduction of calcium retention capacity leading thus to enhanced apoptosis. Therefore, targeting mitochondria might be a promising therapeutic approach in PAD.

Can You Repeat That? Exploring the Definition of a Successful Model Replication in Health Economics

The International Society for Pharmacoeconomics and Outcomes Research (ISPOR) modelling taskforce suggests decision models should be thoroughly reported and transparent. However, the level of transparency and indeed how transparency should be assessed are yet to be defined. One way may be to attempt to replicate the model and its outputs. The ability to replicate a decision model could demonstrate adequate reporting transparency. This review aims to explore published definitions of replication success across all scientific disciplines and to consider how such a definition should be tailored for use in health economic models. A literature review was conducted to identify published definitions of a 'successful replication'. Using these as a foundation, several definitions of replication success were constructed, to be applicable to replications of economic decision models, with the associated strengths and weaknesses of such definitions discussed. A substantial body of literature discussing replicability was found; however, relatively few studies, ten, explicitly defined a successful replication. These definitions varied from subjective assessments to expecting exactly the same results to be reproduced. Whilst the definitions that have been found may help to construct a definition specific to health economics, no definition was found that completely encompassed the unique requirements for decision models. Replication is widely discussed in other scientific disciplines; however, as of yet, there is no consensus on how replicable models should be within health economics or what constitutes a successful replication. Replication studies can demonstrate how transparently a model is reported, identify potential calculation errors and inform future reporting practices. It may therefore be a useful adjunct to other transparency or quality measures.

Aging Exacerbates Ischemia-Reperfusion-Induced Mitochondrial Respiration Impairment in Skeletal Muscle

Cycles of ischemia-reperfusion (IR) that occur during peripheral arterial disease (PAD) are associated with significant morbi-mortality, and aging is an irreversible risk factor of PAD. However, the effects of advanced age on IR-induced skeletal muscle mitochondrial dysfunction are not well known. Young and aged mice were therefore submitted to hindlimb IR (2 h ischemia followed by 2 h reperfusion). Skeletal muscle mitochondrial respiration, calcium retention capacity (CRC) and reactive oxygen species (ROS) production were determined using high resolution respirometry, spectrofluorometry and electronic paramagnetic resonance. IR-induced impairment in mitochondrial respiration was enhanced in old animals (V_ADP; from 33.0 ± 2.4 to 18.4 ± 3.8 and 32.8 ± 1.3 to 5.9 ± 2.7 pmol/s/mg wet weight; −44.2 ± 11.4% vs. −82.0 ± 8.1%, in young and aged mice, respectively). Baseline CRC was lower in old animals and IR similarly decreased the CRC in both groups (from 11.8 ± 0.9 to 4.6 ± 0.9 and 5.5 ± 0.9 to 2.1 ± 0.3 µmol/mg dry weight; −60.9 ± 7.3 and −60.9 ± 4.6%, in young and aged mice, respectively). Further, IR-induced ROS production tended to be higher in aged mice. In conclusion, aging exacerbated the deleterious effects of IR on skeletal muscle mitochondrial respiration, potentially in relation to an increased oxidative stress.

On reproducibility and replicability: Arguing for open science practices and methodological improvements at the South African Journal of Industrial Psychology

Problematisation: In recent years, psychology has been going through a crisis of sorts. Research methods and practices have come under increased scrutiny, with many issues identified as negatively contributing to low replicability and reproducibility of psychological research.Implications: As a consequence, researchers are increasingly called upon to overhaul and improve their research process. Various stakeholders within the scientific community are arguing for more openness and rigor within industrial and organisational (I-O) psychological research. A lack of transparency and openness further fuels criticisms as to the credibility and trustworthiness of I-O psychology which negatively affects the evidence-based practices which it supports. Furthermore, traditional gate-keepers such as grant agencies, professional societies and journals, are adapting their policies, reflecting an effort to curtail these trends.Purpose: The purpose of this opinion paper is, therefore, to stimulate an open dialogue with the South African Journal of Industrial Psychology (SAJIP) contributing authors, its editorial board and readership about the challenges associated with the replication crisis in psychology. Furthermore, it attempts to discuss how the identified issues affect I-O psychology and how these could be managed through open science practices and other structural improvements within the SAJIP.Recommendations: We enumerate several easily implementable open science practices, methodological improvements and editorial policy enhancements to enhance credibility and transparency within the SAJIP. Relying on these, we recommend changes to the current practices that can be taken up by researchers and the SAJIP to improve reproducibility and replicability in I-O psychological science.

Beneficial Effect of Exercise on Cognitive Function during Peripheral Arterial Disease: Potential Involvement of Myokines and Microglial Anti-Inflammatory Phenotype Enhancement

Peripheral arterial disease (PAD), leading to intermittent claudication, critical ischemia with rest pain, and/or tissue damage, is a public health issue associated with significant morbidity and mortality. Little is known about the link between PAD, cognitive function, and whether exercise might reduce cognitive dysfunction in PAD patients, as previously observed concerning both quality of life and prognosis. This review highlights the fact that patients suffering from PAD often demonstrate cognitive dysfunction characterized by reduced performance in nonverbal reasoning, reduced verbal fluency, and decreased information processing speed and a greater risk for progression toward dementia. Further, the data presented support that physical exercise, likely through myokine secretion and microglial anti-inflammatory phenotype enhancement, might participate in the cognition protection in common clinical settings.

N-Acetyl Cysteine Restores Limb Function, Improves Mitochondrial Respiration, and Reduces Oxidative Stress in a Murine Model of Critical Limb Ischaemia

OBJECTIVE/BACKGROUND

The aim of this study was to investigate whether antioxidant therapy might decrease oxidative stress related deleterious effects in the setting of critical limb ischaemia (CLI).

METHODS

Twenty Swiss mice were submitted to sequential right femoral and iliac ligatures; the left limb served as control. The mice were assigned to two groups: in the first group (no-treatment group, n = 10) no treatment was administered; in the second group (N-acetyl cysteine [NAC] group, n = 10) NAC was administered by dissolution in drinking water for 4 weeks, starting on day 7, when CLI was effective. Clinical and functional scores were assessed by two blinded investigators. Mice were killed on day 40 and mitochondrial respiratory chain complex activities, calcium retention capacity, oxidative stress, and histological analysis were analysed.

RESULTS

Ischaemic muscles in the no-treatment group showed significantly impaired mitochondrial respiration and calcium retention capacity, with increased production of reactive oxygen species; but no statistical difference was noticed when comparing ischaemic muscles in the NAC group (n = 10) to contralateral muscles (n = 10) and to control muscles in the no-treatment group (n = 10). Ischaemic muscles in the no-treatment group exhibited myopathic features such as wider range in fibre size, rounded shape, centrally located nuclei, and smaller cross sectional areas, but none of these features were observed in contralateral muscles or in NAC-group muscles (ischaemic or controls).

CONCLUSION

Targeting inhibition of oxidative stress may be a potential therapeutic strategy for muscle protection in CLI and might be considered as potential adjunctive therapy to revascularisation procedures.

Diabetes Worsens Skeletal Muscle Mitochondrial Function, Oxidative Stress, and Apoptosis After Lower-Limb Ischemia-Reperfusion: Implication of the RISK and SAFE Pathways?

Objectives: Diabetic patients respond poorly to revascularization for peripheral arterial disease (PAD) but the underlying mechanisms are not well understood. We aimed to determine whether diabetes worsens ischemia-reperfusion (IR)-induced muscle dysfunction and the involvement of endogenous protective kinases in this process.

Materials and Methods: Streptozotocin-induced diabetic and non-diabetic rats were randomized to control or to IR injury (3 h of aortic cross-clamping and 2 h of reperfusion). Mitochondrial respiration, reactive oxygen species (ROS) production, protein levels of superoxide dismutase (SOD2) and endogenous protective kinases (RISK and SAFE pathways) were investigated in rat gastrocnemius, together with upstream (GSK-3β) and downstream (cleaved caspase-3) effectors of apoptosis.

Results: Although already impaired when compared to non-diabetic controls at baseline, the decline in mitochondrial respiration after IR was more severe in diabetic rats. In diabetic animals, IR-triggered oxidative stress (increased ROS production and reduced SOD2 levels) and effectors of apoptosis (reduced GSK-3β inactivation and higher cleaved caspase-3 levels) were increased to a higher level than in the non-diabetics. IR had no effect on the RISK pathway in non-diabetics and diabetic rats, but increased STAT 3 only in the latter.

Conclusion: Type 1 diabetes worsens IR-induced skeletal muscle injury, endogenous protective pathways not being efficiently stimulated.