Effects of acceleration in the Gz axis on human cardiopulmonary responses to exercise

The aim of this paper was to develop a model from experimental data allowing a prediction of the cardiopulmonary responses to steady-state submaximal exercise in varying gravitational environments, with acceleration in the Gz axis (a g) ranging from 0 to 3g. To this aim, we combined data from three different experiments, carried out at Buffalo, at Stockholm and inside the Mir Station. Oxygen consumption, as expected, increased linearly with a g. In contrast, heart rate increased non-linearly with a g, whereas stroke volume decreased non-linearly: both were described by quadratic functions. Thus, the relationship between cardiac output and a g was described by a fourth power regression equation. Mean arterial pressure increased with a g non linearly, a relation that we interpolated again with a quadratic function. Thus, total peripheral resistance varied linearly with a g. These data led to predict that maximal oxygen consumption would decrease drastically as a g is increased. Maximal oxygen consumption would become equal to resting oxygen consumption when a g is around 4.5g, thus indicating the practical impossibility for humans to stay and work on the biggest Planets of the Solar Syste

The effect of the gravity loading countermeasure skinsuit upon movement and strength

© 2016 National Strength and Conditioning Association. Effective countermeasures against musculoskeletal deconditioning induced by microgravity and disuse are required. A simple alternative to provision of artificial gravity by centrifugation is compressive axial loading. The Russian "Pingvin" suit was the first wearable suit to apply this concept using bungee cords tethered around the shoulders and feet. However, poor loading characteristics and severe thermal and movement discomfort were reported. The gravity loading countermeasure skinsuit (GLCS) uses a bidirectional weave to generate staged axial loading from shoulders to feet, better mimicking how Earth's gravity induces progressive loading head to foot. The Mk III GLCS's loading was evaluated and tolerability assessed during maximal joint motion, ambulation, and selected strength exercises. Eight subjects (5 male and 3 female; 28 ± 3 years; 179 ± 0.1 cm and 74.8 ± 2.9 kg), having given written informed consent, had an Mk III GLCS individually tailored. Axial loading imparted, body height, joint range of motion (ROM), ambulation, and strength tests (12 repetition maximum) were performed in the GLCS and gym attire, with subjective (rating of perceived exertion, thermal comfort, movement discomfort and body control) ratings recorded throughout. Gravity loading countermeasure skinsuit provided significant axial loading when standing but significantly reduced knee (-13°), spinal (-28°) and shoulder flexion/extension ROM (-34°/-13°), in addition to Sit and Reach (-12.8 cm). No thermal issues were reported but there was an increase in subjective discomfort. Gravity loading countermeasure skinsuit did not significantly impede strength exercise, with the exception of shoulder press. The GLCS (Mk III) demonstrates potential as a countermeasure by providing tolerable, static axial loading. Furthermore, it may serve as an elasticlike strength exercise adjunct, which may have utility as a rehabilitation modality after further design refinement

Spaceflight results in increase of thick filament but not thin filament proteins in the paramyosin mutant of Caenorhabditis elegans

We have investigated the effect of microgravity during spaceflight on body-wall muscle fiber size and muscle proteins in the paramyosin mutant of Caenorhabditis elegans. Both mutant and wild-type strains were subjected to 10 days of microgravity during spaceflight and compared to ground control groups. No significant change in muscle fiber size or quantity of the protein was observed in wild-type worms; where as atrophy of body-wall muscle and an increase in thick filament proteins were observed in the paramyosin mutant unc-15(e73) animals after spaceflight. We conclude that the mutant with abnormal muscle responded to microgravity by increasing the total amount of muscle protein in order to compensate for the loss of muscle function

Neocytolysis of red blood cells following high altitude exposure

Introduction: The cellular changes, driven by hypoxia exposure, represent an adequate response to the high altitude environment making newly generated RBCs more fit to manage oxygen uptake and delivery.Objective: to answer following questions: 1) Do the cellular changes, driven by hypoxia exposure, represent an adequate response to the high altitude environment making newly generated RBCs more fit to manage oxygen uptake and delivery? But are these changes still advantageous upon return to normoxia? 2) Does HIF mediated EPO\u2019s increase, in high altitude give rise to a plethora of scarcely selected, hypoxia adapted neocytes whose phenotype makes them susceptible to phagocytosis, upon return to normoxia? 3) Does EPO\u2019s decrease, occurring during de-acclimatisation, the main cause triggering neocytolysis, as the abrogation of neocytolysis in vivo by EPO administration seems to suggest (8)? Methods: A \ufffd\ufffd \ufffd \u20134\ufffd .\ufffdT\ufffd A group of four mountain climbers was studied (age 28\u20134 3 years, two males and two females). Their hematological parameters and RBC phenotype were analysed before and after 53 days acclimatization at high altitude ( 65 4500 m). The RBCs populations were fractionated by density separation into age-based subsets (young, middle-aged and old), the RBCs counts of the three age classes were assessed and some phenotypical features of RBCs from these subsets were investigated by flow cytometry. In particular, the expression of CD55 and CD59 (14) that are partially lost by RBCs during in vitro and in vivo aging (15) were measured. The expression of CD47 (14) and phosphatidylserine (PS) exposure on the outer membrane were also measured. Results: Upon return to sea level, analysis showed a shift to a \u201csenescent-like\u201d phenotype in all RBCs subpopulations, EPO concentration was lower in all subjects as compared with the values measured in control blood samples. Afterthe 6-day descent to sea level, a dramatic decrease in the number of RBCs in the low and middle density subsets and a corresponding increase of cells in the dense subset was observed. Conclusions: The changes make the red cells function more effective even at low PO2 targeting possibly the neocytes to phagocytosis once the mountain climbers return to sea level, i.e. to normoxia. Beside the membrane changes the presence of fetal haemoglobin could imbalance the oxygen uptake/delivery by RBCs in normoxia making them more susceptible to oxidative stress and, ultimately, directing them to \u201csenescence\u201d and phagocytosis

Renal amyloidosis: histochemical and histospectrophotometric study of 50 cases.

PATHOLOGICA (GENOVA