Effect of one year residence in Antarctica on bone mineral metabolism and body composition

Abstract

Objective: To evaluate the changes of the biochemical parameters of mineral metabolism and to assess the effect of these changes on the bone mass of young healthy men who voluntarily lived in the Antarctic Continent for one year. Design: Lumbar spine and whole body bone mineral density (BMD) were measured pre-and post-campaign (14 months later). Serum and urinary biochemical parameters were measured every two months. Serum levels of calcium, phosphate, total alkaline phosphatase, parathormone (PTH) and 25-hydroxyvitamin D (250HD) were determined in blood fasting samples; and hydroxyproline, calcium and creatinine in 2 h fasting urine. The subjects received a dose of 100 IUad of vitamin D during May after obtaining the samples and then an average of 125 IUad from July to January. Subjects: Seventeen healthy volunteers, who left Buenos Aires during the 1992 summer: ten arrived in the Belgrano II Base at the end of January and the other seven arrived in San Martõ Ân in March and stayed there up to summer 1993. Results: BMD increased in lumbar spine (L2±L4), total body and the subarea of the legs but there were no differences between the pre-and post-campaign values in arms and pelvis. The percentage of fat mass decreased signi®cantly after 1 y of residence in Antarctica, in comparison to the basal values. Most biochemical parameters remained unaltered and within the normal range during the whole study. PTH showed a nadir in March (end of the summer) when compared to initial levels (73.0 AE28.2 vs 39.9 AE32.7 pgaml, P`0.05), and recovered its initial value in spring. Calcium levels showed a signi®cant decrease in March (9.5 AE0.4 vs 8.5 AE1.0 mg%, P`0.01). 25OHD levels began to decrease in March (24.7 AE6.4 vs 18.7 AE5.3 ngaml), reaching a minimum value whose difference approached statistical signi®cance during the winter period (July: 16.4 AE8.2 ml, 0.05`P`0.06). No signi®cant changes in serum phosphate, total alkaline phosphatase, urinary hydroxyprolineacreatinine and calciumacreatinine ratios were found through the year. Conclusions: 25OHD levels decreased in autumn and winter (nadir in July) and recovered the initial levels by the end of the campaign. An unexplained marked diminution in PTH and serum calcium was found at the beginning of the campaign. In spite of the low vitamin D levels, bone mass in this group of young healthy men increased, probably because of their intense physical activity.

Genetic and environmental factors of macroelements concentration in blood serum and osseous tissue of lambs in north-west Poland

“…The herd of the Leine sheep remained in the coastal zone of the West Pomerania region, on sandy soils, about 20 km away from the location where the Kent and Polish Merino sheep were kept. The value of calcium concentration in the tissues is influenced by its content in the feed, but also by the element of movement and physical effort (OLIVERI et al 1999), which was unavailable to the pregnant Leine ewes due to the management system. The key role in the biological osseous tissue mineralisation belongs to specialised cells, which initiate and control the process.…”

Vitamin D supplementation during Antarctic winter

“…Antarctica were mostly observational and showed a decrease in 25-hydroxyvitamin D status, as expected (21)(22)(23)(24)(25)(26). A shorter study (49 d) in submariners documented the inability of 400-IU doses to improve 25-hydroxyvitamin D concentrations (27).…”

Skeletal and hormonal responses to sunlight deprivation in Antarctic expeditioners

“…Extreme conditions also limit skin exposure. Reductions in 25(OH)D have been reported in Antarctic expeditioners; however, skeletal changes are inconclusive [9][10][11][12]. We studied Australian Antarctic expeditioners to determine the temporal pattern and magnitude of emerging vitamin D insufficiency, changes in circulating measures of bone remodeling, and rates of bone loss during longterm sunlight deprivation.…”