心臓自律神経機能への体脂肪による影響

Aim of this study was to assess the relation of generalized obesity and fat distribution to sympathetic and parasympathetic components ofheart rate in healthy young subjects. We recorded ECG continuously in the supine and standing position with pacing respiration at 0.25Hz for 5 min in 47 healthy young female. Habitus was represented by body mass index, as an index of generalized adiposity, and by the ratio of waist-to-hip girth (waist/hip ratio), as an index of centripetal fat distribution. A spectral analysis of R-R variability from 256-sec series interbeat interval in each position provided markers of sympathetic nerve activity (ratio of low frequency component to high frequency component (LF /HF ratio) in the standing position), and vagal activity (HF power in the supine position). LF /HF ratio in the standing position was positively correlated with both waist/ hip ratio (r=0.366, p<0.02) and waist girth (r= 0.317, p<0.04), but not correlated with body mass index (p=0.904). HF power in the supine position was not correlated with waist/hip ratio (p=0.893), waist girth (p= 0.907) or body .mass index (p=0.454). These results suggest that, in healthy young female, centripetal fat distribution is one of the determinants of the cardiac sympathetic activity, but not the cardiac vagal activity

Comparing the vertical distribution of iron in the eastern and western North Pacific Ocean

Labile dissolved Fe (<0.22 μm) in the western (165°E) and eastern (165°W) North Pacific Ocean had nutrient- and apparent oxygen utilization (AOU)-like profiles characterized by surface depletion and deep enrichment (5–3000 m depth). Dissolved Fe concentrations in the deep-water column at the mid-latitudes were approximately one-half lower in the eastern region (0.5–0.8 nM) than in the western region (0.8–1.3 nM) although the dissolved Fe concentrations in the surface mixed layer in both regions were extremely depleted to 0.1–0.2 nM. Surprisingly, the labile particulate Fe concentrations (≤∼0.1 nM, total dissolvable Fe minus labile dissolved Fe) throughout the water column at low latitudes in the eastern region were extremely lower than those (∼0.5–1 nM) in the western region. It is suggested that the low Fe levels in the eastern mid-latitude oceanic region are primarily due to the lower atmospheric Fe supply in the eastern region.An edited version of this paper was published by AGU. Copyright 2006, American Geophysical Union, Geophysical Research Letters, 200