Comparing NER Approaches on French Clinical Text, with Easy-to-Reuse Pipelines.

The task of Named Entity Recognition (NER) is central for leveraging the content of clinical texts in observational studies. Indeed, texts contain a large part of the information available in Electronic Health Records (EHRs). However, clinical texts are highly heterogeneous between healthcare services and institutions, between countries and languages, making it hard to predict how existing tools may perform on a particular corpus. We compared four NER approaches on three French corpora and share our benchmarking pipeline in an open and easy-to-reuse manner, using the medkit Python library. We include in our pipelines fine-tuning operations with either one or several of the considered corpora. Our results illustrate the expected superiority of language models over a dictionary-based approach, and question the necessity of refining models already trained on biomedical texts. Beyond benchmarking, we believe sharing reusable and customizable pipelines for comparing fast-evolving Natural Language Processing (NLP) tools is a valuable contribution, since clinical texts themselves can hardly be shared for privacy concerns.

TAXN: Translate Align Extract Normalize, a Multilingual Extraction Tool for Clinical Texts.

Several studies have shown that about 80% of the medical information in an electronic health record is only available through unstructured data. Resources such as medical terminologies in languages other than English are limited and restrain the NLP tools. We propose here to leverage English based resources in other languages using a combination of translation, word alignment, entity extraction and term normalization (TAXN). We implement this extraction pipeline in an open-source library called "medkit". We demonstrate the interest of this approach through a specific use-case: enriching a phenotypic dictionary for post-acute sequelae in COVID-19 (PASC). TAXN proved to be efficient to propose new synonyms of UMLS terms using a corpus of 70 articles in French with 356 terms enriched with at least one validated new synonym. This study was based on freely available deep-learning models.

Wildland fire, air pollution and cardiovascular health: is it time to focus on the microvasculature as a risk assessment tool?

Climate change favors weather conditions conducive to wildland fires. The intensity and frequency of forest fires are increasing, and fire seasons are lengthening. Exposure of human populations to smoke emitted by these fires increases, thereby contributing to airborne pollution through the emission of gas and particulate matter (PM). The adverse health outcomes associated with wildland fire exposure represent an important burden on the economies and health systems of societies. Even though cardiovascular diseases (CVDs) are the main of cause of the global burden of diseases attributable to PM exposure, it remains difficult to show reliable associations between exposure to wildland fire smoke and cardiovascular disease risk in population-based studies. Optimal health requires a resilient and adaptable network of small blood vessels, namely, the microvasculature. Often alterations of this microvasculature precede the occurrence of adverse health outcomes, including CVD. Biomarkers of microvascular health could then represent possible markers for the early detection of poor cardiovascular outcomes. This review aims to synthesize the current literature to gauge whether assessing the microvasculature can better estimate the cardiovascular impact of wildland fires.

Performing one or more verification VO2 workload(s) immediately after an incremental to maximal graded exercise test significantly increases the proportion of participants who meet the job-related aerobic fitness standard for structural firefighters.

PURPOSE: Graded exercise tests (GXTs) are commonly used to determine the maximal oxygen consumption (VO2max) of firefighter applicants. However, the criteria used to confirm VO2max are inconsistent and have a high inter-subject variability, which can compromise the reliability of the results. To address this, a verification phase (VP) after the GXT has been proposed as a "gold standard" protocol for measuring VO2max. METHODS: 4179 male and 283 female firefighter applicants completed a GXT and a VP to measure their VO2max. VO2peak values measured during the GXT were compared to the VO2 values measured during the VP. The proportion of participants who met the job-related aerobic fitness standard during the GXT was compared to that of those who met the required standard during the VP. RESULTS: For male and female participants that required the VP to attain their VO2max, the VO2peak values measured during the GXT (47.3 ± 6.0 and 41.6 ± 5.3 mL kg-1 min-1) were, respectively, 10.1% and 10.3% lower than the VO2 values measured during the VP (52.1 ± 6.7 and 45.9 ± 6.4 mL kg-1 min-1), p < 0.001. Furthermore, the proportion of male and female participants who met the job-related aerobic fitness standard significantly increased from the GXT to the VP by 11.6% and 29.9%, respectively, p < 0.001. CONCLUSION: These results strongly support the use of a VP to confirm VO2max, especially for females, older and overweight individuals. These findings are applicable to other physically demanding public safety occupations and when examining the efficacy of training interventions on VO2max.

Angiostatic freeze or angiogenic move? Acute cold stress prevents angiokine secretion from murine myotubes but primes primary endothelial cells for greater migratory capacity.

The skeletal muscle tissue can adapt to exercise and environmental stressors with a remarkable plasticity. Prolonged cold stress exposure has been associated to increased skeletal muscle capillarization. Angioadaptation refers to the coordinated molecular and cellular processes that influence the remodeling of skeletal muscle microvasculature. Two cell types are central to angioadaptation: the myocytes, representing an important source of angiokines; and the skeletal muscle endothelial cell (SMECs), targets of these angiokines and main constituents of muscle capillaries. The influence of cold stress on skeletal muscle angioadaptation remains largely unknown, particularly with respect to myocyte-specific angiokines secretion or endothelial cell angioadaptive responses. Here, we use an in vitro model to investigate the impact of cold stress (28°C versus 37°C) on C2C12 myotubes and SMECs. Our main objectives were to evaluate: 1) the direct impact of cold stress on C2C12 cellular expression of angiokines and their release in the extracellular environment; 2) the indirect impact of cold stress on SMECs migration via these C2C12-derived angiokines; and 3) the direct effect of cold stress on SMECs angioadaptive responses, including migration, proliferation, and the activation of the vascular endothelial growth factor receptor-2 (VEGFR2). Cold stress reduced the secretion of angiokines in C2C12 myotubes culture media irrespective their pro-angiogenic or angiostatic nature. In SMECs, cold stress abrogated cell proliferation and reduced the activation of VEGFR2 despite a greater expression of this receptor. Finally, SMECs pre-conditioned to cold stress displayed an enhanced migratory response when migration was stimulated in rewarming conditions. Altogether our results suggest that cold stress may be overall angiostatic. However, cold stress accompanied by rewarming may be seen as a pro-angiogenic stressor for SMECs. This observation questions the potential for using pre-cooling in sport-performance or therapeutic exercise prescription to enhance skeletal muscle angioadaptive responses to exercise.

Altitude, Exercise, and Skeletal Muscle Angio-Adaptive Responses to Hypoxia: A Complex Story.

Hypoxia, defined as a reduced oxygen availability, can be observed in many tissues in response to various physiological and pathological conditions. As a hallmark of the altitude environment, ambient hypoxia results from a drop in the oxygen pressure in the atmosphere with elevation. A hypoxic stress can also occur at the cellular level when the oxygen supply through the local microcirculation cannot match the cells' metabolic needs. This has been suggested in contracting skeletal myofibers during physical exercise. Regardless of its origin, ambient or exercise-induced, muscle hypoxia triggers complex angio-adaptive responses in the skeletal muscle tissue. These can result in the expression of a plethora of angio-adaptive molecules, ultimately leading to the growth, stabilization, or regression of muscle capillaries. This remarkable plasticity of the capillary network is referred to as angio-adaptation. It can alter the capillary-to-myofiber interface, which represent an important determinant of skeletal muscle function. These angio-adaptive molecules can also be released in the circulation as myokines to act on distant tissues. This review addresses the respective and combined potency of ambient hypoxia and exercise to generate a cellular hypoxic stress in skeletal muscle. The major skeletal muscle angio-adaptive responses to hypoxia so far described in this context will be discussed, including existing controversies in the field. Finally, this review will highlight the molecular complexity of the skeletal muscle angio-adaptive response to hypoxia and identify current gaps of knowledges in this field of exercise and environmental physiology.

High Glucose Treatment Limits Drosha Protein Expression and Alters AngiomiR Maturation in Microvascular Primary Endothelial Cells via an Mdm2-dependent Mechanism.

Diabetes promotes an angiostatic phenotype in the microvascular endothelium of skeletal muscle and skin. Angiogenesis-related microRNAs (angiomiRs) regulate angiogenesis through the translational repression of pro- and anti-angiogenic genes. The maturation of micro-RNA (miRs), including angiomiRs, requires the action of DROSHA and DICER proteins. While hyperglycemia modifies the expression of angiomiRs, it is unknown whether high glucose conditions alter the maturation process of angiomiRs in dermal and skeletal muscle microvascular endothelial cells (MECs). Compared to 5 mM of glucose, high glucose condition (30 mM, 6-24 h) decreased DROSHA protein expression, without changing DROSHA mRNA, DICER mRNA, or DICER protein in primary dermal MECs. Despite DROSHA decreasing, high glucose enhanced the maturation and expression of one angiomiR, miR-15a, and downregulated an miR-15a target: Vascular Endothelial Growth Factor-A (VEGF-A). The high glucose condition increased Murine Double Minute-2 (MDM2) expression and MDM2-binding to DROSHA. Inhibition of MDM2 prevented the effects evoked by high glucose on DROSHA protein and miR-15a maturation in dermal MECs. In db/db mice, blood glucose was negatively correlated with the expression of skeletal muscle DROSHA protein, and high glucose decreased DROSHA protein in skeletal muscle MECs. Altogether, our results suggest that high glucose reduces DROSHA protein and enhances the maturation of the angiostatic miR-15a through a mechanism that requires MDM2 activity.

The effects of single versus multiple training sessions on the motor learning of two Krav Maga strike techniques, in women.

BACKGROUND: Experts of the Krav Maga (KM) self-defense system propose that KM techniques are based on simple body movements which are suggested to be learned rapidly and retained. This study investigated the acquisition, retention, and further improvement with additional training of two KM strike techniques among novice female practitioners: straight punch and defensive kick. METHODS: Sixteen healthy females (age: 23 ± 3.7 years) without any previous martial arts/self-defense experience volunteered to participate. All participants received an initial 30-min instruction session (AQ), taught by a certified KM instructor, where each technique was deconstructed into three checkpoints (defined as a component of the entire movement) for learning. Participants were divided into two groups, one of which received additional training. Several kinematic and kinetic measures were recorded at four timepoints: immediately before AQ, immediately after AQ, 5 days after AQ, and 12 days after AQ. RESULTS: Results suggest that both techniques were learned rapidly, as checkpoint performance was significantly improved after AQ. Kick velocity and impact force also increased significantly after AQ; however, these measures did not change after AQ for the punch technique. Additional training did not improve either punch or kick performance beyond that learned during AQ. CONCLUSION: The findings from this study suggest that a single training session may be sufficient to learn and retain KM strike techniques relatively permanently; and the acquisition of the kick technique may lead to concomitant improvements in kick velocity and impact force.

High-fat diet pre-conditioning improves microvascular remodelling during regeneration of ischaemic mouse skeletal muscle.

AIM: Critical limb ischaemia (CLI) is characterized by inadequate angiogenesis, arteriolar remodelling and chronic myopathy, which are most severe in type 2 diabetic patients. Hypertriglyceridaemia, commonly observed in these patients, compromises macrovascular function. However, the effects of high-fat diet-induced increases in circulating lipids on microvascular remodelling are not established. Here, we investigated if high-fat diet would mimic the detrimental effect of type 2 diabetes on post-ischaemia vascular remodelling and muscle regeneration, using a mouse model of hindlimb ischaemia. METHODS: Male C57Bl6/J mice were fed with normal or high-fat diets for 8 weeks prior to unilateral femoral artery ligation. Laser doppler imaging was used to assess limb perfusion recovery. Vascular recovery, inflammation, myofibre regeneration and fibrosis were assessed at 4 or 14 days post-ligation by histology and RNA analyses. Capillary-level haemodynamics were assessed by intravital microscopy of control and regenerating muscles 14 days post-ligation. RESULTS: High-fat diet increased muscle succinate dehydrogenase activity and capillary-level oxygen supply. At 4 days post-ligation, no diet differences were detected in muscle damage, inflammatory infiltration or capillary activation. At 14 days post-ligation, high fat-fed mice displayed accelerated limb blood flow recovery, elevated capillary and arteriole densities as well as greater red blood cell supply rates and capillary-level oxygen supply. Regenerating muscles from high fat-fed mice displayed lower interstitial fat and collagen deposition. CONCLUSION: The muscle-level adaptations to high-fat diet improved multiple aspects of muscle recovery in response to ischaemia and did not recapitulate the worse outcomes seen in diabetic CLI patients.

Hyperglycaemia correlates with skeletal muscle capillary regression and is associated with alterations in the murine double minute-2/forkhead box O1/thrombospondin-1 pathway in type 1 diabetic BioBreeding rats.

Type 1 diabetes can have deleterious effects on skeletal muscle and its microvasculature. Our laboratory has recently identified murine double minute-2 as a master regulator of muscle microvasculature by controlling expression levels of two key molecular actors of the angio-adaptive process: the pro-angiogenic vascular endothelial growth factor-A and the anti-angiogenic thrombospondin-1. Here, we show for the first time that in the soleus and plantaris muscles of the diabetes-prone BioBreeding rats, a rodent model of autoimmune type 1 diabetes, murine double minute-2 protein levels are significantly decreased, coinciding with elevated protein levels of thrombospondin-1 and its transcription factor forkhead box O1. Significant capillary regression was observed to similar extent in soleus and plantaris muscles of type 1 diabetic rats. Elevated blood glucose levels were correlated with the loss of capillaries, the reduction in murine double minute-2 expression and with the elevations in thrombospondin-1. Vascular endothelial growth factor-A protein levels were unaltered or even increased in diabetic animals, yet type 1 diabetic animals had less vascular endothelial growth factor receptor-2 abundance. The vascular endothelial growth factor-A/thrombospondin-1 ratio, a good indicator of skeletal muscle angio-adaptive environment, was decreased in type 1 diabetic muscle. Our results suggest that the murine double minute-2-forkhead box O1-thrombospondin-1 pathway plays an important role in angio-regulation of the skeletal muscle in the pathophysiological context of type 1 diabetes.

The effects of voluntary exercise and prazosin on capillary rarefaction and metabolism in streptozotocin-induced diabetic male rats.

Type-1 diabetes mellitus (T1D) causes impairments within the skeletal muscle microvasculature. Both regular exercise and prazosin have been shown to improve skeletal muscle capillarization and metabolism in healthy rats through distinct angiogenic mechanisms. The aim of this study was to evaluate the independent and additive effects of voluntary exercise and prazosin treatment on capillary-to-fiber ratio (C:F) in streptozotocin (STZ)-treated diabetic rats. STZ (65 mg/kg) was intraperitoneally administered to male Sprague-Dawley rats (n = 36) to induce diabetes, with healthy, nondiabetic, sedentary rats (n = 10) as controls. The STZ-treated rats were then divided into sedentary (SED) or exercising (EX; 24-h access to running wheels) groups and then further subdivided into prazosin (Praz) or water (H2O) treatment groups: nondiabetic-SED-H2O, STZ-SED-H2O, STZ-EX-H2O, STZ-SED-Praz, and STZ-EX-Praz. After 3 wk, untreated diabetes significantly reduced the C:F in tibialis anterior (TA) and soleus muscles in the STZ-SED-H2O animals (both P < 0.05). Voluntary exercise and prazosin treatment independently resulted in a normalization of C:F within the TA (1.86 ± 0.12 and 2.04 ± 0.03 vs 1.71 ± 0.09, P < 0.05) and the soleus (2.36 ± 0.07 and 2.68 ± 0.14 vs 2.13 ± 0.12, P < 0.05). The combined STZ-EX-Praz group resulted in the highest C:F within the TA (2.26 ± 0.07, P < 0.05). Voluntary exercise volume was negatively correlated with fed blood glucose levels (r2 = -0.7015, P < 0.01) and, when combined with prazosin, caused further enhanced nonfasted glucose (P < 0.01). Exercise and prazosin reduced circulating nonesterified fatty acids more than either stimulus alone (P < 0.05). These results suggest that the distinct stimulation of angiogenesis, with both regular exercise and prazosin treatment, causes a cooperative improvement in the microvascular complications associated with T1D.NEW & NOTEWORTHY It is currently well established that poorly controlled diabetes reduces both skeletal muscle mass and muscle capillarization. These muscle-specific features of diabetes may, in turn, compromise insulin sensitivity and glucose control. Using a model of streptozotocin-induced diabetes, we show the vascular complications linked with disease and how chronic exposure to exercise and prazosin (an α1-adrenergic antagonist) can reduce these complications and improve glycemic control.

The Vascular Endothelial Growth Factor-A phosphorylates Murine Double Minute-2 on its Serine 166 via the Extracellular Signal-Regulated Kinase 1/2 and p90 Ribosomal S6 Kinase in primary human endothelial cells.

Murine Double Minute-2 (Mdm2) has been identified as an essential regulator of skeletal muscle angiogenesis and the pro-angiogenic activity of endothelial cells. We have recently demonstrated that the pro-angiogenic Vascular Endothelial Growth Factor-A (VEGF-A) is a potent upstream regulator of Mdm2 phosphorylation on its Serine 166 (p-Ser166-Mdm2), a protein modification leading to an increase in endothelial cell migration. Here, we investigated the kinase signaling pathways that could be responsible for mediating VEGF-A-dependent Mdm2 phosphorylation. Incubation of primary human dermal microvascular endothelial cells with recombinant VEGF-A for 15 min led to increased phosphorylation levels of VEGF-receptor-2, Mdm2, Akt, Extracellular Signal-Regulated Kinase 1/2 (ERK1/2), and p90 Ribosomal S6 Kinase (p90RSK) proteins. In addition to being linked to VEGF-A signaling, Akt, ERK1/2 and p90RSK have been shown to potentially lead to Mdm2 phosphorylation. We therefore next analyzed which of these kinases could be responsible for VEGF-A-dependent Mdm2 phosphorylation on Serine 166 by using kinase-specific pharmacological inhibitors. Inhibition of ERK1/2 phosphorylation by UO126 entirely abrogated the response of p-Ser166-Mdm2 to VEGF-A treatment, while Akt phosphorylation inhibition by wortmannin led to further elevations in p-Ser166-Mdm2. p90RSK has been identified as a potential candidate downstream of ERK1/2 that could induce Mdm2 Ser166 phosphorylation. Two independent p90RSK inhibitors, FMK and BI-D1870, each led to an entire loss of p-Ser166-Mdm2 responsiveness to VEGF-A. Taken together, our results demonstrate that VEGF-A driven Mdm2 phosphorylation on Ser166 is dependent on the ERK1/2/p90RSK signaling pathway in primary human endothelial cells, furthering our understanding of the complex relationship between Mdm2 and VEGF-A in a physiological context.

Skeletal Muscle Insulin Resistance and Absence of Inflammation Characterize Insulin-Resistant Grade I Obese Women.

CONTEXT: Obesity is associated with insulin-resistance (IR), the key feature of type 2 diabetes. Although chronic low-grade inflammation has been identified as a central effector of IR development, it has never been investigated simultaneously at systemic level and locally in skeletal muscle and adipose tissue in obese humans characterized for their insulin sensitivity. OBJECTIVES: We compared metabolic parameters and inflammation at systemic and tissue levels in normal-weight and obese subjects with different insulin sensitivity to better understand the mechanisms involved in IR development. METHODS: 30 post-menopausal women were classified as normal-weight insulin-sensitive (controls, CT) and obese (grade I) insulin-sensitive (OIS) or insulin-resistant (OIR) according to their body mass index and homeostasis model assessment of IR index. They underwent a hyperinsulinemic-euglycemic clamp, blood sampling, skeletal muscle and subcutaneous adipose tissue biopsies, an activity questionnaire and a self-administrated dietary recall. We analyzed insulin sensitivity, inflammation and IR-related parameters at the systemic level. In tissues, insulin response was assessed by P-Akt/Akt expression and inflammation by macrophage infiltration as well as cytokines and IκBα expression. RESULTS: Systemic levels of lipids, adipokines, inflammatory cytokines, and lipopolysaccharides were equivalent between OIS and OIR subjects. In subcutaneous adipose tissue, the number of anti-inflammatory macrophages was higher in OIR than in CT and OIS and was associated with higher IL-6 level. Insulin induced Akt phosphorylation to the same extent in CT, OIS and OIR. In skeletal muscle, we could not detect any inflammation even though IκBα expression was lower in OIR compared to CT. However, while P-Akt/Akt level increased following insulin stimulation in CT and OIS, it remained unchanged in OIR. CONCLUSION: Our results show that systemic IR occurs without any change in systemic and tissues inflammation. We identified a muscle defect in insulin response as an early mechanism of IR development in grade I obese post-menopausal women.

Phosphorylation of murine double minute-2 on Ser166 is downstream of VEGF-A in exercised skeletal muscle and regulates primary endothelial cell migration and FoxO gene expression.

We demonstrated in a previous study that murine double minute (Mdm)-2 is essential for exercise-induced skeletal muscle angiogenesis. In the current study, we investigated the mechanisms that regulate Mdm2 activity in response to acute exercise and identified VEGF-A as a key stimulator of Mdm2 phosphorylation on Ser(166) (p-Ser166-Mdm2). VEGF-A and p-Ser166-Mdm2 protein levels were measured in human and rodent muscle biopsy specimens after 1 bout of exercise. VEGF-A-dependent Mdm2 phosphorylation was demonstrated in vivo in mice harboring myofiber-specific deletion of VEGF-A (mVEGF(-/-)) and in vitro in primary human and rodent endothelial cells (ECs). Exercise increased VEGF-A and p-Ser166-Mdm2 protein levels respectively by 157 and 68% in human muscle vs. pre-exercise levels. Similar results were observed in exercised rodent muscles compared to sedentary controls; however, exercise-induced Mdm2 phosphorylation was significantly attenuated in mVEGF(-/-) mice. Recombinant VEGF-A elevated p-Ser166-Mdm2 by 50-125% and stimulated migration by 33% in ECs when compared to untreated cells, whereas the Mdm2 antagonist Nutlin-3a abrogated VEGF-driven EC migration. Finally, overexpression of a Ser166-Mdm2 phosphorylation mimetic increased EC migration, increased Mdm2 to FoxO1 binding (+55%), and decreased FoxO1-dependent gene expression compared with ECs overexpressing WT-Mdm2. Our results suggest that VEGF-mediated Mdm2 phosphorylation on Ser(166) is a novel proangiogenic pathway within the skeletal muscle.

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. While the expression of the pro-inflammatory and pro-angiogenic cytokines IL-6, TNF-α and VEGF-A was high during and after CNC, we observed that inhibition of VEGF-A receptors strongly counteracted the angiogenic response induced by the ex vivo CNC. Activation of the pro-survival transcription factor nuclear factor-kappa B (NF-κB) increased during CNC, returning to control levels after nerve decompression. After nerve decompression, the downregulation of Mdm2 correlated well with an increased expression of pro-apoptotic transcription factor p53. All together, we bring novel evidence that CNC activates transcription factors such as NF-κB and p53, which are key effectors of the cellular stress response, suggesting a neuroprotective process associated with an increased VEGF-A-mediated neurotrophic effect. Our results highlight the role of pro-angiogenic and pro-inflammatory cytokines during CNC that are reinforced by increasing neurotrophic capacity during recovery to promote nerve regeneration.

Forkhead BoxO transcription factors restrain exercise-induced angiogenesis.

The physiological process of exercise-induced angiogenesis involves the orchestrated upregulation of angiogenic factors together with repression of angiostatic factors. The Forkhead Box 'O' (FoxO) transcription factors promote an angiostatic environment in pathological contexts. We hypothesized that endothelial FoxO1 and FoxO3a also play an integral role in restricting the angiogenic response to aerobic exercise training. A single exercise bout significantly increased levels of FoxO1 and FoxO3a mRNA (5.5- and 1.7-fold, respectively) and protein (1.7- and 2.2-fold, respectively) within the muscles of mice 2 h post-exercise compared to sedentary. Training abolished the exercise-induced increases in both FoxO1 and FoxO3a mRNA and proteins, and resulted in significantly lower nuclear levels of FoxO1 and FoxO3a protein (0.5- and 0.4-fold, respectively, relative to sedentary). Thrombospondin 1 (THBS1) protein level closely mirrored the expression pattern of FoxO proteins. The 1.7-fold increase in THBS1 protein following acute exercise no longer occurred after 10 days of repeated exercise. Endothelial cell-directed conditional deletion of FoxO1/3a/4 in mice prevented the increase in THBS1 mRNA following a single exercise bout. Mice harbouring the endothelial FoxO deletion also demonstrated a significant 20% increase in capillary to muscle fibre ratio after only 7 days of training while 14 days of training was required to elicit a similar increase in wildtype littermates. Our results demonstrate that the downregulation of FoxO1 and FoxO3a proteins facilitates angiogenesis in response to repeated exercise. In conclusion, FoxO proteins can delay exercise-induced angiogenesis, and thus are critical regulators of the physiological angiogenic response in skeletal muscle.

Angiogenesis: growth points.

This collection of papers is based on talks presented at the IUPS meeting in Birmingham, UK last summer, in a symposium as part of the ESM & EVBO program, sponsored by the British Microcirculation Society and Microcirculation. In this issue we discuss new insights into the control of angiogenesis, including regulation of different aspects of endothelial cell biology by the tissue stroma, during inflammatory disease, and active remodelling of the microcirculation. We address a variety of signalling modes that determine the endothelial responses to pro-angiogenic stimuli, including necessary synergy among different pathways and processes. We present an update of recent developments, and identify some areas where significant progress will likely occur.

Novel perspective: exercise training stimulus triggers the expression of the oncoprotein human double minute-2 in human skeletal muscle.

High expression levels of human double minute-2 (Hdm2) are often associated with increased risk of cancer. Hdm2 is well established as an oncoprotein exerting various tumorigenic effects. Conversely, the physiological functions of Hdm2 in nontumor cells and healthy tissues remain largely unknown. We previously demonstrated that exercise training stimulates expression of murine double minute-2 (Mdm2), the murine analog of Hdm2, in rodent skeletal muscle and Mdm2 was required for exercise-induced muscle angiogenesis. Here we showed that exercise training stimulated the expression of Hdm2 protein in human skeletal muscle from +38% to +81%. This robust physiological response was observed in 60-70% of the subjects tested, in both young and senior populations. Similarly, exercise training stimulated the expression of platelet endothelial cell adhesion molecule-1, an indicator of the level of muscle capillarization. Interestingly, a concomitant decrease in the tumor suppressor forkhead box O-1 (FoxO1) transcription factor levels did not occur with training although Mdm2/Hdm2 is known to inhibit FoxO1 expression in diseased skeletal muscle. This could suggest that Hdm2 has different targets when stimulated in a physiological context and that exercise training could be considered therapeutically in the context of cancer in combination with anti-Hdm2 drug therapies in order to preserve Hdm2 physiological functions in healthy tissues.

Endothelial FoxO1 is an intrinsic regulator of thrombospondin 1 expression that restrains angiogenesis in ischemic muscle.

Peripheral artery disease (PAD) is characterized by chronic muscle ischemia. Compensatory angiogenesis is minimal within ischemic muscle despite an increase in angiogenic factors. This may occur due to the prevalence of angiostatic factors. Regulatory mechanisms that could evoke an angiostatic environment during ischemia are largely unknown. Forkhead box O (FoxO) transcription factors, known to repress endothelial cell proliferation in vitro, are potential candidates. Our goal was to determine whether FoxO proteins promote an angiostatic phenotype within ischemic muscle. FoxO1 and the angiostatic matrix protein thrombospondin 1 (THBS1) were elevated in ischemic muscle from PAD patients, or from mice post-femoral artery ligation. Mice with conditional endothelial cell-directed deletion of FoxO proteins (Mx1Cre (+), FoxO1,3,4 (L/L) , referred to as FoxOΔ) were used to assess the role of endothelial FoxO proteins within ischemic tissue. FoxO deletion abrogated the elevation of FoxO1 and THBS1 proteins, enhanced hindlimb blood flow recovery and improved neovascularization in murine ischemic muscle. Endothelial cell outgrowth from 3D explant cultures was more robust in muscles derived from FoxOΔ mice. FoxO1 overexpression induced THBS1 production, and a direct interaction of endogenous FoxO1 with the THBS1 promoter was detectable in primary endothelial cells. We provide evidence that FoxO1 directly regulates THBS1 within ischemic muscle. Altogether, these findings bring novel insight into the regulatory mechanisms underlying the repression of angiogenesis within peripheral ischemic tissues.

Blunted muscle angiogenic training-response in COPD patients versus sedentary controls.

The impaired skeletal muscle of chronic obstructive pulmonary disease (COPD) patients reduces exercise capacity. Similar to the oxidative muscle fibres, the angio-adaptation of muscle to training may be blunted in these patients, as in other chronic conditions. We therefore compared muscle functional responses and angio-adaptations after training in COPD patients and sedentary healthy subjects (SHS). 24 COPD patients (forced expiratory volume in 1 s 45.6 ± 17.5% predicted) and 23 SHS (<150 min · week(-1) of moderate-to-vigorous exercise) completed a 6-week rehabilitation programme based on individualised moderate-intensity endurance training. Histomorphological muscle analysis and measurements of pro-angiogenic vascular endothelial growth factor (VEGF)-A and anti-angiogenic thrombospondin (TSP)-1 were conducted before and after training. COPD patients and SHS showed improved symptom-limited oxygen consumption and muscle endurance, although improvements were lower in COPD patients (+0.96 ± 2.4 versus +2.9 ± 2.6 mL · kg(-1) · min(-1), p<0.05, and +65% versus +108%, p = 0.06, respectively). The capillary-to-fibre (C/F) ratio increased less in COPD patients than SHS (+16 ± 10% versus +37 ± 20%, p<0.05) and no fibre type switch occurred in COPD patients. The VEGF-A/TSP-1 ratio increased in COPD patients and SHS (+65% versus +35%, p<0.05). Changes in C/F and symptom-limited oxygen consumption were correlated (r = 0.51, p<0.05). In addition to a lack of fibre switch, COPD patients displayed a blunted angiogenic response to training.