A Shovel With a Perforated Blade Reduces Energy Expenditure Required for Digging Wet Clay

Objective: A shovel with a blade perforated with small holes was tested to see whether a worker would use less whole-body energy to dig wet clay than with a shovel with an opaque blade. Background: A perforated shovel is hypothesized to require less whole-body energy on the basis of adhesion theory; a smaller surface area would require less physical effort to dig and release soil from the blade. Method: The study involved 13 workers from an electric utility who dug wet clay with two 1.5-m long-handled point shovels, which differed only in blade design (perforated and opaque). Oxygen consumption was measured with a portable system while each worker dug wet clay at a self-regulated pace for 10 min. Results: There was no significant difference in number of scoops dug during the 10-min sessions, but workers dug 9.5% more weight of clay with the perforated shovel than with the conventional shovel (404 kg vs. 369 kg, respectively). Furthermore, stable oxygen uptake normalized to weight of participant and to the weight of clay dug revealed that participants expended 11.7% less relative energy per kilogram of clay dug with the perforated shovel. Conclusion: A point shovel with a perforated blade is recommended for digging and shoveling wet clay. However, the extra weight that workers chose to dig with the perforated shovel may increase the loading on the spine and may offset the metabolic advantages. Application: Manual shoveling is a common task, and workers may experience less whole-body and muscle fatigue when using a perforated shovel

Respiratory challenge MRI: practical aspects

Respiratory challenge MRI is the modification of arterial oxygen (PaO2) and/or carbon dioxide (PaCO2) concentration to induce a change in cerebral function or metabolism which is then measured by MRI. Alterations in arterial gas concentrations can lead to profound changes in cerebral haemodynamics which can be studied using a variety of MRI sequences. Whilst such experiments may provide a wealth of information, conducting them can be complex and challenging. In this paper we review the rationale for respiratory challenge MRI including the effects of oxygen and carbon dioxide on the cerebral circulation. We also discuss the planning, equipment, monitoring and techniques that have been used to undertake these experiments. We finally propose some recommendations in this evolving area for conducting these experiments to enhance data quality and comparison between techniques

Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 144

This bibliography lists 257 reports, articles, and other documents introduced into the NASA scientific and technical information system in July 1975

Aerospace medicine and biology: A continuing bibliography with indexes, supplement 129, June 1974

This special bibliography lists 280 reports, articles, and other documents introduced into the NASA scientific and technical information system in May 1974

Methods and protocols for incremental exercise testing in tetraplegia, using arm-crank ergometry assisted by Functional Electrical Stimulation

Cervical spinal cord injury (SCI) leads to tetraplegia, with paralysis and loss of sensation in the upper and lower limbs. The associated sedentary lifestyle results in an increased risk of cardiovascular disease. To address this, we require the design of exercise modalities aimed specifically at tetraplegia and methods to assess their efficacy. This paper describes methods for arm-crank ergometry (ACE) assisted by Functional Electrical Stimulation (FES) applied to the biceps and triceps. The instrumented ergometer enables work-rate control during exercise, implemented here for incremental exercise testing during FES-ACE. Detailed protocols for the tests are given. Experimental data collected during exercise tests with tetraplegic volunteers are provided to illustrate the feasibility of the proposed approach to testing and data analysis. Incremental tests enabled calculation of peak power output and peak oxygen uptake. We propose that the high-precision exercise testing protocols described here are appropriate to assess the efficacy of the novel exercise modality, FES-ACE, in tetraplegia

Physiological responses of reared sea bream (Sparus aurata Linnaeus, 1758) to an Amyloodinium ocellatum outbreak

Amyloodiniosis represents a major bottleneck for semi-intensive aquaculture production in Southern Europe, causing extremely high mortalities. Amyloodinium ocellatum is a parasitic dinoflagellate that can infest almost all fish, crustacean and bivalves that live within its ecological range. Fish mortalities are usually attributed to anoxia, associated with serious gill hyperplasia, inflammation, haemorrhage and necrosis in heavy infestations; or with osmoregulatory impairment and secondary microbial infections due to severe epithelial damage in mild infestation. However, physiological information about the host responses to A.ocellatum infestation is scarce. In this work, we analysed the proteome of gilthead sea bream (Sparus aurata) plasma and relate it with haematological and immunological indicators, in order to enlighten the different physiological responses when exposed to an A.ocellatum outbreak. Using 2D-DIGE, immunological and haematological analysis and in response to the A.ocellatum contamination we have identified several proteins associated with acute-phase response, inflammation, lipid transport, homoeostasis, and osmoregulation, wound healing, neoplasia and iron transport. Overall, this preliminary study revealed that amyloodiniosis affects some fish functional pathways as revealed by the changes in the plasma proteome of S. aurata, and that the innate immunological system is not activated in the presence of the parasite.DIVERSIAQUA, Portugal [MAR2020]Fundacao para a Ciencia e Tecnologia [SFRH/BD/118601/2016]info:eu-repo/semantics/publishedVersio

Pathophysiology of Apnea, Hypoxia, and Preoxygenation

Because intubation becomes a long procedure as potential, arterial oxygen (O2) desatu-ration should be taken into account during the intubation. Since oxygen reserves are not always sufficient to meet the duration of intubation, preoxygenation should be routine before anesthetic induction and tracheal intubation. Surveys show that maximal preoxygenation increases oxygen reserves in the body and significantly delays arterial hemoglobin desaturation and hypoxia. In cases of respiratory insufficiency oxygenation can be improved by positive end expiratory pressure (PEEP) or pressure support. Effective technique and FeO2 monitoring can increase the effectiveness of preoxygenation and thus increase the safety margin. Preoxygenation failures have to be identified and alternative oxygenation methods must be readily available in order to be applied quickly and easily. Although genetic and environmental factors play a role in diseases such as heart attack, stroke and cancer, which have become the cause of the worst death in the twenty-first century, the underlying problem in the development of these pathological conditions is hypoxia. Better understanding of hypoxic areas in ischemic tissues or growing tumors as well as increased knowledge of hypoxia cellular and molecular responses will allow possible applications in the treatment of major diseases associated with tissue hypoxia

Following one's heart: cardiac rhythms gate central initiation of sympathetic reflexes

Central nervous processing of environmental stimuli requires integration of sensory information with ongoing autonomic control of cardiovascular function. Rhythmic feedback of cardiac and baroreceptor activity contributes dynamically to homeostatic autonomic control. We examined how the processing of brief somatosensory stimuli is altered across the cardiac cycle to evoke differential changes in bodily state. Using functional magnetic resonance imaging of brain and noninvasive beat-to-beat cardiovascular monitoring, we show that stimuli presented before and during early cardiac systole elicited differential changes in neural activity within amygdala, anterior insula and pons, and engendered different effects on blood pressure. Stimulation delivered during early systole inhibited blood pressure increases. Individual differences in heart rate variability predicted magnitude of differential cardiac timing responses within periaqueductal gray, amygdala and insula. Our findings highlight integration of somatosensory and phasic baroreceptor information at cortical, limbic and brainstem levels, with relevance to mechanisms underlying pain control, hypertension and anxiety

Acute and short-term normobaric hypoxic conditioning on psycho-physiological responses in obese populations

This thesis investigated the psycho-physiological responses of obese individuals during and following acute and short-term hypoxic conditioning, including both passive and active modalities. Study one determined psycho-physiological responses to passive hypoxic conditioning (FiO2= 12.0%) consisting of varying hypoxic and normoxic cycles in obese individuals. It was found that perceptions of breathlessness following short (15 × 2 mins hypoxia/2 mins normoxia) cycles was lowest (-7%) for up to 60 mins post-exposure compared to long cycles (5 × 6 mins hypoxia/6 mins normoxia), whilst the extent of desaturation in arterial oxygen satura tion was greater in the latter than the former (-4%). The fndings of this study later informed the interval work/rest duration of exercising in hypoxia for obese individuals. Study two assessed psycho-physiological responses of trained runners during a perceptually regulated interval running session (4 × 4 mins at a rating of perceived exertion equal to 16, 3mins recovery) in hypoxic (FiO2 = 15.0%) and normoxic conditions. The main findings show that a slower treadmill velocity (-6%) was required to maintain a rating of perceived exertion equal to 16 in hypoxia than normoxia. Whilst physiological responses were matched between conditions (i.e., heart rate and muscle oxygenation), exercise-related sensations (i.e., perceived recovery [-21%], motivation [-21%], breathlessness [+22%%], limb discomfort [+11%%] and pleasure [-31%]) were negatively impacted more so during hypoxia compared to normoxia. The findings of this study provided an intial insight regarding the influence of hypoxia on the perceptually-regulated exercise model in trained runners prior to utilisation in an obese population. Study three assessed psycho-physiological responses of obese individuals during a perceptually-regulated interval walking session (15 × 2 mins walking, 2 mins recovery, based on the findings of study one) in hypoxic (FiO2 = 13.0%) and normoxic conditions. Further, during an additional third condition, the psycho-physiological responses from hypoxia were isolated with the velocity selected during this trial matched in normoxic conditions. Similar to study three, a slower treadmill velocity (-2%) was required to maintain a rating of perceived exertion equal to 14 in hypoxia than normoxia. Physiological responses were more pronounced during hypoxia compared to normoxia (i.e., higher heart rate [+6%] and lower muscle oxygenation [-6%]), whilst perceptions of limb discomfort were lower (-21%) in the former than the latter. In the absence of hypoxia at the same velocity, perceptions of limb discomfort were matched to perceptually-regulated walking in hypoxia, but the physiological stress was lower (i.e., heart rate [-5%]). The findings of this study provided indication of the acute effects of perceptually-regulated interval walking in hypoxia prior to implementation of this protocol design on a regular, short-term basis. Study four examined the psycho-physiological responses of obese individuals to a short-term training intervention (utilising the same session protocol of study three, eight sessions in two weeks) in hypoxic (FiO2 = 13.0%) and normoxic conditions. A similar perceptually-regulated velocity, physiological stress (i.e., heart rate) and exercise-related sessions (i.e., perceived recovery, motivation, breathlessness, limb discomfort and pleasure) were recorded during training between conditions. Improvements in perceived mood state (+12%), exercise-selfefficacy (+11%) and energy expenditure (+10%) were reported after training independent of condition, whilst resting blood glucose levels were only enhanced after hypoxic training (-15%). Collectively, obese individuals may benefit in terms of psycho-physiological responses from exercising at a perceptually-regulated intensity in hypoxia more so than normoxia. These benefits (acute and short-term) could be potentiated largely due to the optimisation of cycle variations of hypoxia/normoxia and exercise/rest durations

Bioabsorbable metal zinc differentially affects mitochondria in vascular endothelial and smooth muscle cells

Zinc is an essential trace element having various structural, catalytic and regulatory interactions with an estimated 3000 proteins. Zinc has drawn recent attention for its use, both as pure metal and alloyed, in arterial stents due to its biodegradability, biocompatibility, and low corrosion rates. Previous studies have demonstrated that zinc metal implants prevent the development of neointimal hyperplasia, which is a common cause of restenosis following coronary intervention. This suppression appears to be smooth muscle cell-specific, as reendothelization of the neointima is not inhibited. To better understand the basis of zinc\u27s differential effects on rat aortic smooth muscle (RASMC) versus endothelial (RAENDO) cells, we conducted a transcriptomic analysis of both cell types following one-week continuous treatment with 5 µM or 50 µM zinc. This analysis indicated that genes whose protein products regulate mitochondrial functions, including oxidative phosphorylation and fusion/fission, are differentially affected by zinc in the two cell types. To better understand this, we performed Seahorse metabolic flux assays and quantitative imaging of mitochondrial networks in both cell types. Zinc treatment differently affected energy metabolism and mitochondrial structure/function in the two cell types. For example, both basal and maximal oxygen consumption rates were increased by zinc in RASMC but not in RAENDO. Zinc treatment increased apparent mitochondrial fusion in RASMC cells but increased mitochondrial fission in RAENDO cells. These results provide some insight into the mechanisms by which zinc treatment differently affects the two cell types and this information is important for understanding the role of zinc treatment in vascular cells and improving its use in biodegradable metal implants