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GAO, YOUNG Y, JENNIFER C LOVEJOY, ANDREA SPARTI, GEORGE A BRAY, L KEN KEYS AND CURTIS PARTINGTON. Autonomic activity assessed by heart rate spectral analysis varies with fat distribution in obese women. Obes Res. 1996;4:55-63. Obesity in humans has been associated with altered autonomic nervous system activity. The objective of this study was to examine the relationship between autonomic function and body fat distribution in 16 obese, postmenopausal women using power spectrum analysis of heart rate variability. Using this technique, a low frequency peak (0.04-0.12 Hz) reflecting mixed sympathetic and parasympathetic activity, and a high frequency peak (0.22-0.28 Hz) reflecting parasympathetic activity, were identified from 5-minute consecutive heart rate data (both supine and standing). Autonomic activity in upper body (UBO) vs. lower body obesity (LBO)(by waistto-hip ratio) and subcutaneous vs, visceral obesity (by CT scan) was evaluated. Power spectrum data were log transformed to normalize the data. The results showed that standing, low-frequency power (reflecting sympathetic activity) and supine, high-frequency power (reflecting parasympathetic activity) were significantly greater in uno than in LBO, and in visceral compared to subcutaneous obesity. Women with combined uno and visceral obesity had significantly higher cardiac sympathetic and parasympa- thetic activity than any other subgroup. We conclude that cardiac autonomic function as assessed by heart rate spectral analysis varies in women depending on their regional body fat distribution.

Magnetic-susceptibility measurements of the Magneli phases of the Ti-0 system show a change from weak covalent bond formation, through antiferromagnetic to paramagnetic-like behavior with increasing oxygen concentration. The reciprocal molar susceptibility plotted versus temperature indicates collective electron effects in all phases except TiOi.50 and TiOi.67. These exhibit noncooperative and cooperative semiconductor-to-metal transitions, respectively.

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