« Go Back

Research Containing: Linear Models

Iron status and its relations with oxidative damage and bone loss during long-duration space flight on the International Space Station

by on 9 June 2015in Biology & Biotechnology No comment

BACKGROUND: Increases in stored iron and dietary intake of iron during space flight have raised concern about the risk of excess iron and oxidative damage, particularly in bone. OBJECTIVES: The objectives of this study were to perform a comprehensive assessment of iron status in men and women before, during, and after long-duration space flight and to quantify the association of iron status with oxidative damage and bone loss. DESIGN: Fasting blood and 24-h urine samples were collected from 23 crew members before, during, and after missions lasting 50 to 247 d to the International Space Station. RESULTS: Serum ferritin and body iron increased early in flight, and transferrin and transferrin receptors decreased later, which indicated that early increases in body iron stores occurred through the mobilization of iron to storage tissues. Acute phase proteins indicated no evidence of an inflammatory response during flight. Serum ferritin was positively correlated with the oxidative damage markers 8-hydroxy-2'-deoxyguanosine (r = 0.53, P < 0.001) and prostaglandin F2alpha (r = 0.26, P < 0.001), and the greater the area under the curve for ferritin during flight, the greater the decrease in bone mineral density in the total hip (P = 0.031), trochanter (P = 0.006), hip neck (P = 0.044), and pelvis (P = 0.049) after flight. CONCLUSION: Increased iron stores may be a risk factor for oxidative damage and bone resorption.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/23719548

Adaptation of heart rate and blood pressure to short and long duration space missions

by on 9 June 2015in Biology & Biotechnology No comment

To what extent does going to space affect cardiovascular function? Although many studies have addressed this question, the answer remains controversial. Even for such primary parameters as heart rate (HR) and blood pressure (BP) contradictory results have been presented. The purpose of this investigation was to evaluate HR and arterial BP in 11 male astronauts who each took part in nine different space missions aboard the International Space Station (ISS), for up to 6 months. Pre-flight HR and BP readings were obtained in both the standing and supine positions on Earth and were taken as reference values. Our results show that HR and arterial BP in space equal pre-flight supine values. In all subjects, HR and mean arterial BP (MAP) were lower in space compared with pre-flight standing (both 0.05). HR in space was well maintained at pre-flight supine level for up to 6 months in all astronauts while MAP tended to adapt to a level in between the ground-based standing and supine positions. Also pulse pressure (PP) decreased over the course of long duration spaceflight. In conclusion, our data indicate that weightlessness relaxes the circulation in humans for an extended duration of up to 6 months in space.

Related URLs:
http://www.sciencedirect.com/science/article/pii/S1569904809000652

Weight loss in humans in space

by on 9 June 2015in Biology & Biotechnology No comment

INTRODUCTION: Bodyweight loss during spaceflight has been observed among astronauts since the early space missions. Considerable mission data has been accumulated, including data from female astronauts, on the many Shuttle and International Space Station missions. The purpose of this study was to investigate the association between observed weight loss during spaceflight and potential covariate factors. METHODS: We performed a statistical analysis of the association between bodyweight change and plausible clinical and mission covariates, using data obtained from the NASA Longitudinal Study of Astronaut Health (LSAH). RESULTS: We confirmed that spaceflight is associated with weight change (-2.1 +/- 0.1%, N = 514). Prospective predictors of weight loss included: being a first-time astronaut, preflight bodyweight and BMI, routinely performing preflight exercise sessions lasting greater than 1 h, and baseline levels of cholesterol, potassium, and chloride. Severe space motion sickness was significantly associated with greater weight loss. Unexpectedly, a higher number of extravehicular activities per mission protected against weight loss. Mission duration had the strongest association with bodyweight change (-2.4 +/- 0.4% per 100 d in space). DISCUSSION: On average, space missions are associated with cumulative loss of bodyweight over time. Unless effective countermeasures are implemented, significant weight loss will be a likely outcome in a subset of astronauts as mission durations increase. New predictors of intra-mission bodyweight changes and other associated factors are identified.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/21702312