Sagittal plane joint kinetics during stair ascent in patients with peripheral arterial disease and intermittent claudication

Stair negotiation poses a substantial physical demand on the musculoskeletal system and this challenging task can place individuals at risk of falls. Peripheral arterial disease (PAD) can cause intermittent claudication (IC) pain in the calf and results in altered gait mechanics during level walking. However, whether those with PAD-IC adopt alternate strategies to climb stairs is unknown. Twelve participants with PAD-IC (six bilateral and six unilateral) and 10 healthy controls were recruited and instructed to ascend a five-step staircase whilst 3D kinematic data of the lower-limbs were recorded synchronously with kinetic data from force plates embedded into the staircase on steps two and three. Limbs from the unilateral group and both limbs from the bilateral claudicants were categorised as claudicating (N = 18), asymptomatic (N = 6) and control (N = 10). Claudicants walked more slowly than healthy controls (trend; P = < 0.066). Both claudicating- and asymptomatic-limb groups had reduced propulsive GRF (P = 0.025 and P = 0.002, respectively) and vertical GRF (P = 0.005 and P = 0.001, respectively) compared to controls. The claudicating-limb group had a reduced knee extensor moment during forward continuance (P = 0.060), ankle angular velocity at peak moment (P = 0.039) and ankle power generation (P = 0.055) compared to the controls. The slower gait speed, irrespective of laterality of symptoms, indicates functional capacity was determined by the limitations of the claudicating limb. Reduced ankle power generation and angular velocity (despite adequate plantarflexor moment) implies velocity-dependent limitations existed in the calf. The lack of notable compensatory strategies indicates reliance on an impaired muscle group to accomplish this potentially hazardous task, highlighting the importance of maintaining plantarflexor strength and power in those with PAD-IC

Dynamic muscle quality of the plantar flexors is impaired in claudicant patients with peripheral arterial disease and associated with poorer walking endurance

Objectives: Peripheral arterial disease and intermittent claudication (PAD-IC) negatively affects physical activity and function. There is evidence for plantarflexor muscle dysfunction and weakness, however, the extent to which this dysfunction can be attributed to reduced muscle size and/or quality is not yet known. This study investigated whether in vivo plantarflexor muscle quality during static and dynamic contractions are altered by PAD-IC and whether such changes are associated with impaired walking endurance (according to initial and absolute claudication distances). Methods: A total of 22 participants were recruited, consisting of 10 healthy controls and 12 claudicants with occlusion of the superficial femoral artery (seven unilateral and five bilateral). Muscle quality of the combined gastrocnemius muscles during static contractions was calculated by normalising the estimated maximal potential muscle force to the physiological cross-sectional area of both lateral and medial gastrocnemius. Muscle quality during dynamic contractions of the combined plantarflexor muscles was calculated as the ratio of peak voluntary concentric plantarflexor power and the summed volume of lateral and medial gastrocnemius. Results: Dynamic muscle quality was 24% lower in both the claudicating-limb and asymptomatic-limb groups compared to controls (P=.017 and P=.023). The differences were most apparent at the highest contraction velocity (180°/s). Dynamic muscle quality was associated with reduced walking endurance (R=.689, P=.006 and R=.550, P=.042 for initial and absolute claudication distance, respectively). The claudicating-limb group demonstrated a trend towards reduced static muscle quality compared to controls (22%, P=.084). The relative contribution of the soleus muscle to plantarflexion maximum voluntary contraction was significantly higher in both claudicating-limb and asymptomatic-limb groups compared to controls (P=.012 and P=.018). Conclusions: The muscle strength of the plantarflexors in those with PAD-IC appears to be impaired at high contraction velocities. This may be explained by some reduction in gastrocnemii muscle quality and a greater reliance on the prominently type I fibred soleus muscle. The reduced dynamic capability of the plantarflexor muscles was associated with disease severity and walking ability, therefore efforts to improve plantarflexor power through dynamic exercise intervention are vital to maintain functional performance

The role of mentorship in protege performance

The role of mentorship on protege performance is a matter of importance to academic, business, and governmental organizations. While the benefits of mentorship for proteges, mentors and their organizations are apparent, the extent to which proteges mimic their mentors' career choices and acquire their mentorship skills is unclear. Here, we investigate one aspect of mentor emulation by studying mentorship fecundity---the number of proteges a mentor trains---with data from the Mathematics Genealogy Project, which tracks the mentorship record of thousands of mathematicians over several centuries. We demonstrate that fecundity among academic mathematicians is correlated with other measures of academic success. We also find that the average fecundity of mentors remains stable over 60 years of recorded mentorship. We further uncover three significant correlations in mentorship fecundity. First, mentors with small mentorship fecundity train proteges that go on to have a 37% larger than expected mentorship fecundity. Second, in the first third of their career, mentors with large fecundity train proteges that go on to have a 29% larger than expected fecundity. Finally, in the last third of their career, mentors with large fecundity train proteges that go on to have a 31% smaller than expected fecundity.Comment: 23 pages double-spaced, 4 figure

Joint moment strategies during stair descent in patients with peripheral arterial disease and intermittent claudication

Objective: To determine the lower limb joint kinetic strategies during stair descent in claudicants with peripheral arterial disease (PAD-IC). Design: Cross-sectional observation study. Setting: University laboratory. Participants: A total of 22 participants; 10 healthy controls and 12 patients diagnosed with PAD-IC. Main Outcome Measures: Between-group comparisons of ground reaction force (GRF) and, hip, knee and ankle kinetics during steady-state stair descent. Results: The claudicating-limb group demonstrated reduced vertical and posterior GRF compared to healthy controls (ES=-1.46 [-2.32,-0.69] and ES=-1.08 [-0.42,-0.26] as well as demonstrating a greater contribution to support moment from the ankle and trends towards a smaller hip contribution (42±14% vs 28±7%, P=.005 and Hip 16±8% vs 21±11%, P=.056, respectively). A unique sub-group was identified within the PAD-IC cohort demonstrating different hip moment strategies during weight acceptance: a novel hip extensor group (PAD-IC HExt) and stereotypical hip flexor group (PAD-IC HFlex). Compared to both healthy controls and the PAD-IC HFlex groups, the PAD-IC HExt group demonstrated increased hip extensor moment (ES=3.05 [1.67,4.42] and ES=3.62 [1.89,5.35]) and reduced knee extensor moment (ES=-2.00 [-3.15,-0.85] and ES=-1.36 [-2.60,-0.11] respectively) during weight acceptance. Conclusions: A novel hip extensor strategy was identified in a sub-group of claudicants which acts to reduce the demand on the knee extensors, but not the plantarflexors. Weakness in the knee extensors may prevent redistribution of the task demand, typically seen in older adults in stair descent, away from the functionally limited plantarflexor muscle group. Further investigation into multi-level joint strength and the relationship to functional tasks is warranted to inform targeted intervention programmes

Workshop by VEMCO

19–22 May 2022 Kyoto, Japa

Achieving elimination as a public health problem for schistosoma mansoni and S. haematobium: when is community-wide treatment required?

The World Health Organization (WHO) has set elimination as a public health problem (EPHP) as a goal for schistosomiasis. As the WHO treatment guidelines for schistosomiasis are currently under revision, we investigate whether school-based or community-wide treatment strategies are required for achieving the EPHP goal. In low- to moderate-transmission settings with good school enrolment, we find that school-based treatment is sufficient for achieving EPHP. However, community-wide treatment is projected to be necessary in certain high-transmission settings as well as settings with low school enrolment. Hence, the optimal treatment strategy depends on setting-specific factors such as the species present, prevalence prior to treatment, and the age profile of infection

Gastrocnemii structure and specific tension in claudicants with peripheral arterial disease

Peripheral arterial disease (PAD) is a chronic, atherosclerotic disease and often presents with intermittent claudication (IC): muscle pain brought on by muscular activity due to reduced oxygen supply and metabolite removal. PAD-IC most commonly affects the lower limbs in the elderly, limiting mobility and physical activity. The combination of disease and disuse likely impacts on muscle size, structure and quality (specific tension; ST). These musculoskeletal characteristics are important determinants of muscle strength and physical function, both of which are known to be reduced in PAD-IC (McDermott et al., 2008).The aims of this study were to determine whether the 1) size and structure, and 2) specific tension of the gastrocnemii muscles were altered with PAD-IC.The muscle (ML), tendon (TL) and fascicle (FL) lengths and pennation (θ) were measured at rest and during isometric MVC at optimum ML in the lateral (GL) and medial gastrocnemius (GM) of 10 controls, 7 uni-lateral and 6 bi-lateral claudicants, using ultrasonography. Volume and physiological cross sectional area (PCSA) were calculated for a combined gastrocnemii group (GS). Joint MVCs were corrected for voluntary and antagonist activation and moment arm length, and were normalised to GS PCSA to calculate ST for the combined muscle group. Between group differences were analysed using an ANOVA. Pearson’s correlations were used to determine associations between disease severity, assessed using ankle:brachial pressure index, and musculoskeletal parameters. No significant differences were found between groups for any structural or functional variable. With increasing disease severity, TL decreased (R=0.59, p=0.02) and GL and GM FL relative to TL increased (R=~-0.70 p<0.001). Trends towards reduced GS PCSA (R=0.50, p=0.06) and GL θ (R=0.35, p=0.16) were evident. No relationship existed between disease severity and plantarflexion MVC (p=0.74) or GS ST (p=0.85). Increasing severity of PAD-IC resulted in altered muscle-tendon structure; muscle and fibre length increased and tendon length reduced. Such adaptations may act to reduce the energy cost of active length changes, thereby attenuating the functional losses in an ischemic environment. The apparent lack of between-group differences in gastrocnemii structure may be due to a masking effect caused by the range of disease severity. In addition, the lack of an association between disease severity and ST suggests intrinsic muscle “quality” is preserved despite clear clinical progressions in disease. Therefore the “quality” of the muscle should not be a limiting factor in the strength, function and response to training of claudicants

Hydration strategies of professional elite rugby league referees during super league matches

Due to the focus of research within athletic populations, little is known about the hydration strategies of rugby league referees. We observed all 8 full-time professional referees, during 31 Super League matches to investigate the drinking strategies and magnitude of dehydration (body mass loss) experienced by referees during match play. Referees arrived and remained euhydrated (urine osmolality; pre and post-match 558 ± 310 and 466 ± 283 mOsmol•kg-1). Mean body mass change was -0.7 ± 0.8%, fluid loss was 890 ± 435 g and fluid intake was 444 ± 167, 438 ± 190, 254 ± 108 and 471 ± 221 g during pre-match, first-half, half-time and second-half. This study suggests elite referees adopt appropriate hydration strategies during match-play to prevent large reductions in body mass, although individual variability was observed. Future research should investigate dehydration in referees from other sports and the effects on refereeing performance

Induction of fibroblast senescence generates a non-fibrogenic myofibroblast phenotype that differentially impacts on cancer prognosis

Cancer-associated fibroblasts (CAF) remain a poorly characterized, heterogeneous cell population. Here we characterized two previously described tumor-promoting CAF sub-types, smooth muscle actin (SMA)-positive myofibroblasts and senescent fibroblasts, identifying a novel link between the two

Inter-domain networking innovation on steroids: Empowering IXPs with SDN capabilities

While innovation in inter-domain routing has remained stagnant for over a decade, Internet Exchange Points (IXPs) are consolidating their role as economically advantageous interconnection points for reducing path latencies and exchanging ever increasing amounts of traffic. As such, IXPs appear as a natural place to foster network innovation and assess the benefits of Software-Defined Networking (SDN), a recent technological trend that has already boosted innovation within data-center networks. In this paper, we give a comprehensive overview of use cases for SDN at IXPs, which leverage the superior vantage point of an IXP to introduce advanced features like load-balancing and DDoS mitigation. We discuss the benefits of SDN solutions by analyzing real-world data from one of the largest IXPs. We also leverage insights into IXP operations to not only shape benefits for members but also for operators.This research is (in part) supported by European Union’s Horizon 2020 research and innovation programme under the ENDEAVOUR project (grant agreement 644960).This is the author accepted manuscript. The final version is available from IEEE via https://doi.org/ 10.1109/MCOM.2016.758827