Comparison of Joint and Muscle Biomechanics in Maximal Flywheel Squat and Leg Press

The aim was to compare the musculoskeletal load distribution and muscle activity in two types of maximal flywheel leg-extension resistance exercises: horizontal leg press, during which the entire load is external, and squat, during which part of the load comprises the body weight. Nine healthy adult habitually strength-training individuals were investigated. Motion analysis and inverse dynamics-based musculoskeletal modelling were used to compute joint loads, muscle forces, and muscle activities. Total exercise load (resultant ground reaction force; rGRF) and the knee-extension net joint moment (NJM) were slightly and considerably greater, respectively, in squat than in leg press (p ≤ 0.04), whereas the hip-extension NJM was moderately greater in leg press than in squat (p = 0.03). Leg press was performed at 11° deeper knee-flexion angle than squat (p = 0.01). Quadriceps muscle activity was similar in squat and leg press. Both exercise modalities showed slightly to moderately greater force in the vastii muscles during the eccentric than concentric phase of a repetition (p ≤ 0.05), indicating eccentric overload. That the quadriceps muscle activity was similar in squat and leg press, while rGRF and NJM about the knee were greater in squat than leg press, may, together with the finding of a propensity to perform leg press at deeper knee angle than squat, suggest that leg press is the preferable leg-extension resistance exercise, both from a training efficacy and injury risk perspective

Lateral thermokarst patterns in permafrost peat plateaus in northern Norway

Subarctic peatlands underlain by permafrost contain significant amounts of organic carbon. Our ability to quantify the evolution of such permafrost landscapes in numerical models is critical for providing robust predictions of the environmental and climatic changes to come. Yet, the accuracy of large-scale predictions has so far been hampered by small-scale physical processes that create a high spatial variability of thermal surface conditions, affecting the ground thermal regime and thus permafrost degradation patterns. In this regard, a better understanding of the small-scale interplay between microtopography and lateral fluxes of heat, water and snow can be achieved by field monitoring and process-based numerical modeling. Here, we quantify the topographic changes of the Šuoššjávri peat plateau (northern Norway) over a three-year period using drone-based repeat high-resolution photogrammetry. Our results show thermokarst degradation is concentrated on the edges of the plateau, representing 77 % of observed subsidence, while most of the inner plateau surface exhibits no detectable subsidence. Based on detailed investigation of eight zones of the plateau edge, we show that this edge degradation corresponds to an annual volume change of 0.13±0.07 m3 yr−1 per meter of retreating edge (orthogonal to the retreat direction). Using the CryoGrid3 land surface model, we show that these degradation patterns can be reproduced in a modeling framework that implements lateral redistribution of snow, subsurface water and heat, as well as ground subsidence due to melting of excess ice. By performing a sensitivity test for snow depths on the plateau under steady-state climate forcing, we obtain a threshold behavior for the start of edge degradation. Small snow depth variations (from 0 to 30 cm) result in highly different degradation behavior, from stability to fast degradation. For plateau snow depths in the range of field measurements, the simulated annual volume changes are broadly in agreement with the results of the drone survey. As snow depths are clearly correlated with ground surface temperatures, our results indicate that the approach can potentially be used to simulate climate-driven dynamics of edge degradation observed at our study site and other peat plateaus worldwide. Thus, the model approach represents a first step towards simulating climate-driven landscape development through thermokarst in permafrost peatlands

Iron deposition and increased alveolar septal capillary density in nonfibrotic lung tissue are associated with pulmonary hypertension in idiopathic pulmonary fibrosis

<p>Abstract</p> <p>Background</p> <p>Early diagnosis of pulmonary hypertension (PH) in idiopathic pulmonary fibrosis (IPF) has potential prognostic and therapeutic implications but can be difficult due to the lack of specific clinical manifestations or accurate non-invasive tests. Histopathologic parameters correlating with PH in IPF are also not known. Remodeling of postcapillary pulmonary vessels has been reported in the nonfibrotic areas of explanted lungs from IPF patients. We hypothesized that iron deposition and increased alveolar capillaries, the findings often seen in postcapillary PH, might predict the presence of clinical PH, independent of the severity of fibrosis or ventilatory dysfunction in IPF patients. To test this hypothesis, we examined the association between these histologic parameters and the degree of PH, with consideration of the severity of disease in IPF.</p> <p>Methods</p> <p>Iron deposition and alveolar septal capillary density (ASCD) were evaluated on histologic sections with hematoxylin-eosin, iron, elastin and CD34 stainings. Percentage of predicted forced vital capacity (FVC%) was used for grading pulmonary function status. Fibrosis score assessed on high resolution computed tomography (HRCT) was used for evaluating overall degree of fibrosis in whole lungs. Right ventricular systolic pressure (RVSP) by transthoracic echocardiography was used for the estimation of PH. Univariate and multivariate regression analyses were performed.</p> <p>Results</p> <p>A cohort of 154 patients was studied who had the clinicopathological diagnosis of IPF with surgical lung biopsies or explants during the period of 1997 to 2006 at Mayo Clinic Rochester. In univariate analysis, RVSP in our IPF cases was associated with both iron deposition and ASCD (p < 0.001). In multivariate analysis with FVC% and HRCT fibrosis score included, iron deposition (p = 0.02), but not ASCD (p = 0.076), maintained statistically significant association with RVSP. FVC% was associated with RVSP on univariate analysis but not on multivariate analysis, while fibrosis score lacked any association with RVSP by either univariate or multivariate analyses.</p> <p>Conclusions</p> <p>Iron deposition and ASCD in non fibrotic lung tissue showed an association with RVSP, suggesting that these features are possible morphologic predictors of PH in IPF.</p

Indices of Increased Decompression Stress Following Long-Term Bed Rest

Human extravehicular activity (EVA) is essential to space exploration and involves risk of decompression sickness (DCS). On Earth, the effect of microgravity on physiological systems is simulated in an experimental model where subjects are confined to a 6° head-down bed rest (HDBR). This model was used to investigate various resting and exercise regimen on the formation of venous gas emboli (VGE), an indicator of decompression stress, post-hyperbaric exposure. Eight healthy male subjects participating in a bed rest regimen also took part in this study, which incorporated five different hyperbaric exposure (HE) interventions made before, during and after the HDBR. Interventions i–iv were all made with the subjects lying in 6° HD position. They included (C1) resting control, (C2) knee-bend exercise immediately prior to HE, (T1) HE during the fifth week of the 35-day HDBR period, (C3) supine cycling exercise during the HE. In intervention (C4), subjects remained upright and ambulatory. The HE protocol followed the Royal Navy Table 11 with 100 min spent at 18 m (280 kPa), with decompression stops at 6 m for 5 min, and at 3 m for 15 min. Post-HE, regular precordial Doppler audio measurements were made to evaluate any VGE produced post-dive. VGE were graded according to the Kisman Masurel scale. The number of bubbles produced was low in comparison to previous studies using this profile [Kisman integrated severity score (KISS) ranging from 0–1], and may be because subjects were young, and lay supine during both the HE and the 2 h measurement period post-HE for interventions i–iv. However, the HE during the end of HDBR produced significantly higher maximum bubble grades and KISS score than the supine control conditions (p &lt; 0.01). In contrast to the protective effect of pre-dive exercise on bubble production, a prolonged period of bed rest prior to a HE appears to promote the formation of post-decompression VGE. This is in contrast to the absence of DCS observed during EVA. Whether this is due to a difference between hypo- and hyperbaric decompression stress, or that the HDBR model is a not a good model for decompression sensitivity during microgravity conditions will have to be elucidated in future studies

Exploring global barriers to optimal ovarian cancer care:thematic analysis

Objective: To explore the barriers to ovarian cancer care, as reported in the open ended responses of a global expert opinion survey, highlighting areas for improvement in global ovarian cancer care. Potential solutions to overcome these barriers are proposed. Methods: Data from the expert opinion survey, designed to assess the organization of ovarian cancer care worldwide, were analyzed. The survey was distributed across a global network of physicians. We examined free text, open ended responses concerning the barriers to ovarian cancer care. A qualitative thematic analysis was conducted to identify, analyze, and report meaningful patterns within the data. Results: A total of 1059 physicians from 115 countries completed the survey, with 438 physicians from 93 countries commenting on the barriers to ovarian cancer care. Thematic analysis gave five major themes, regardless of income category or location: societal factors, inadequate resources in hospital, economic barriers, organization of the specialty, and need for early detection. Suggested solutions include accessible resource stratified guidelines, multidisciplinary teamwork, public education, and development of gynecological oncology training pathways internationally. Conclusions: This analysis provides an international perspective on the main barriers to optimal ovarian cancer care. The themes derived from our analysis highlight key target areas to focus efforts to reduce inequalities in global care. Future regional analysis involving local representatives will enable country specific recommendations to improve the quality of care and ultimately to work towards closing the care gap

Exploring global barriers to optimal ovarian cancer care:thematic analysis

Objective: To explore the barriers to ovarian cancer care, as reported in the open ended responses of a global expert opinion survey, highlighting areas for improvement in global ovarian cancer care. Potential solutions to overcome these barriers are proposed. Methods: Data from the expert opinion survey, designed to assess the organization of ovarian cancer care worldwide, were analyzed. The survey was distributed across a global network of physicians. We examined free text, open ended responses concerning the barriers to ovarian cancer care. A qualitative thematic analysis was conducted to identify, analyze, and report meaningful patterns within the data. Results: A total of 1059 physicians from 115 countries completed the survey, with 438 physicians from 93 countries commenting on the barriers to ovarian cancer care. Thematic analysis gave five major themes, regardless of income category or location: societal factors, inadequate resources in hospital, economic barriers, organization of the specialty, and need for early detection. Suggested solutions include accessible resource stratified guidelines, multidisciplinary teamwork, public education, and development of gynecological oncology training pathways internationally. Conclusions: This analysis provides an international perspective on the main barriers to optimal ovarian cancer care. The themes derived from our analysis highlight key target areas to focus efforts to reduce inequalities in global care. Future regional analysis involving local representatives will enable country specific recommendations to improve the quality of care and ultimately to work towards closing the care gap

Exploring international differences in ovarian cancer care: a survey report on global patterns of care, current practices, and barriers

OBJECTIVE: Although global disparities in survival rates for patients with ovarian cancer have been described, variation in care has not been assessed globally. This study aimed to evaluate global ovarian cancer care and barriers to care. METHODS: A survey was developed by international ovarian cancer specialists and was distributed through networks and organizational partners of the International Gynecologic Cancer Society, the Society of Gynecologic Oncology, and the European Society of Gynecological Oncology. Respondents received questions about care organization. Outcomes were stratified by World Bank Income category and analyzed using descriptive statistics and logistic regressions. RESULTS: A total of 1059 responses were received from 115 countries. Respondents were gynecological cancer surgeons (83%, n=887), obstetricians/gynecologists (8%, n=80), and other specialists (9%, n=92). Income category breakdown was as follows: high-income countries (46%), upper-middle-income countries (29%), and lower-middle/low-income countries (25%). Variation in care organization was observed across income categories. Respondents from lower-middle/low-income countries reported significantly less frequently that extensive resections were routinely performed during cytoreductive surgery. Furthermore, these countries had significantly fewer regional networks, cancer registries, quality registries, and patient advocacy groups. However, there is also scope for improvement in these components in upper-middle/high-income countries. The main barriers to optimal care for the entire group were patient co-morbidities, advanced presentation, and social factors (travel distance, support systems). High-income respondents stated that the main barriers were lack of surgical time/staff and patient preferences. Middle/low-income respondents additionally experienced treatment costs and lack of access to radiology/pathology/genetic services as main barriers. Lack of access to systemic agents was reported by one-third of lower-middle/low-income respondents. CONCLUSIONS: The current survey report highlights global disparities in the organization of ovarian cancer care. The main barriers to optimal care are experienced across all income categories, while additional barriers are specific to income levels. Taking action is crucial to improve global care and strive towards diminishing survival disparities and closing the care gap

Cutaneous exposure to hypoxia does not affect skin perfusion in humans.

$\textbf{Aim:}$ Experiments have indicated that skin perfusion in mice is sensitive to reductions in environmental O$_2$ availability. Specifically, a reduction in skin-surface PO$_2$ attenuates transcutaneous O$_2$ diffusion, and hence epidermal O$_2$ supply. In response, epidermal HIF-1$\alpha$ expression increases and facilitates initial cutaneous vasoconstriction and subsequent nitric oxide-dependent vasodilation. Here, we investigated whether the same mechanism exists in humans. $\textbf{Methods:}$ In a first experiment, eight males rested twice for 8 h in a hypobaric chamber. Once, barometric pressure was reduced by 50%, while systemic oxygenation was preserved by O$_2$-enriched (42%) breathing gas (Hypoxia$_\text{Skin}$), and once barometric pressure and inspired O$_2$ fraction were normal (Control$_1$). In a second experiment, nine males rested for 8 h with both forearms wrapped in plastic bags. O$_2$ was expelled from one bag by nitrogen flushing (Anoxia$_\text{Skin}$), whereas the other bag was flushed with air (Control$_2$). In both experiments, skin blood flux was assessed by laser Doppler on the dorsal forearm, and HIF-1$\alpha$ expression was determined by immunohistochemical staining in forearm skin biopsies. $\textbf{Results:}$ Skin blood flux during Hypoxia$_\text{Skin}$ and Anoxia$_\text{Skin}$ remained similar to the corresponding Control trial ($P$ = 0.67 and $P$ = 0.81). Immunohistochemically stained epidermal HIF-1$\alpha$ was detected on 8.2 ± 6.1 and 5.3 ± 5.7% of the analysed area during Hypoxia$_\text{Skin}$ and Control$_1$ ($P$ = 0.30) and on 2.3 ± 1.8 and 2.4 ± 1.8% during Anoxia$_\text{Skin}$ and Control$_2$ ($P$ = 0.90) respectively. $\textbf{Conclusion:}$ Reductions in skin-surface PO$_2$ do not affect skin perfusion in humans. The unchanged epidermal HIF-1$\alpha$ expression suggests that epidermal O$_2$ homoeostasis was not disturbed by Hypoxia$_\text{Skin}$/Anoxia$_\text{Skin}$, potentially due to compensatory increases in arterial O$_2$ extraction.Gösta Fraenckel Foundatio

Interpreting archaeological site-formation processes at a mountain ice patch: A case study from Langfonne, Norway

In the context of global warming, ice patches are increasingly important foci of high-elevation archaeology. Langfonne in Jotunheimen, central southern Norway, is uniquely suited to provide a window onto site formation processes and taphonomy in this novel archaeological setting. Here the site record from systematic survey includes the largest number of arrows, bones and antlers from a single ice patch worldwide. Combining data from these finds with the results of glaciological investigations provides an opportunity to interpret the influence of archaeological site formation processes and taphonomy on chronological and spatial patterning. It is inferred that the spatial patterning of artefacts at Langfonne is partly a result of displacement by ice movement, meltwater and other natural processes. Nevertheless, the finds yield information regarding past hunting practices and the extent of ice at different times. An early cluster of finds from c.6000 cal yr BP may result from ice deformation which has brought early objects to the surface. The number of arrows increases from c. 1700 cal yr BP onwards, peaking around c.1200 cal yr BP. Artefacts from this period show a wide spatial distribution indicating both the preferential survival of more recent finds and that they were lost when the ice patch was large. Based on comparison with the chronology of natural bone and antler samples from the site, the greater number of finds of this date may also reflect a period of increased hunting. </jats:p