Rapid suppression of bone formation marker in response to sleep restriction and circadian disruption in men.

We describe the time course of bone formation marker (P1NP) decline in men exposed to ~ 3 weeks of sleep restriction with concurrent circadian disruption. P1NP declined within 10 days and remained lower with ongoing exposure. These data suggest even brief exposure to sleep and circadian disruptions may disrupt bone metabolism. INTRODUCTION: A serum bone formation marker (procollagen type 1 N-terminal, P1NP) was lower after ~ 3 weeks of sleep restriction combined with circadian disruption. We now describe the time course of decline. METHODS: The ~ 3-week protocol included two segments: "baseline," ≥ 10-h sleep opportunity/day × 5 days; "forced desynchrony" (FD), recurring 28 h day (circadian disruption) with sleep restriction (~ 5.6-h sleep per 24 h). Fasted plasma P1NP was measured throughout the protocol in nine men (20-59 years old). We tested the hypothesis that PINP would steadily decline across the FD intervention because the magnitude of sleep loss and circadian misalignment accrued as the protocol progressed. A piecewise linear regression model was used to estimate the slope (ß) as ΔP1NP per 24 h with a change point mid-protocol to estimate the initial vs. prolonged effects of FD exposure. RESULTS: Plasma P1NP levels declined significantly within the first 10 days of FD ([Formula: see text] = - 1.33 µg/L per 24 h, p < 0.0001) and remained lower than baseline with prolonged exposure out to 3 weeks ([Formula: see text] = - 0.18 µg/L per 24 h, p = 0.67). As previously reported, levels of a bone resorption marker (C-telopeptide (CTX)) were unchanged. CONCLUSION: Sleep restriction with concurrent circadian disruption induced a relatively rapid decline in P1NP (despite no change in CTX) and levels remained lower with ongoing exposure. These data suggest (1) even brief sleep restriction and circadian disruption can adversely affect bone metabolism, and (2) there is no P1NP recovery with ongoing exposure that, taken together, could lead to lower bone density over time.

Optimal conditions for accumulation of bioavailable iron in Saccharomyces cerevisiae cells.

Growth and proliferation of brewer's yeast Saccharomyces cerevisiae in the presence of different Fe2+ levels was studied with the aim of finding optimal conditions for a maximum accumulation of bioavailable iron bound to constituents of yeast cells. The results demonstrated that iron stimulates growth and proliferation only under conditions of intensive aeration. Iron accumulation and the effect of aeration were examined in the presence 3.6 microM - 7.2 mM Fe2+, while its content in the cells after 20 h cultivation was determined by atomic absorption spectrophotometry. Control cultures were grown in no iron added medium. Further experiments revealed that iron concentrations ranging from 3.6 microM to 3.6 mM were beneficial to growth and proliferation, while higher levels did not affect these processes. The above range of iron concentrations also led to a more extensive iron accumulation, while further increase expressed no effect. So, Fe2+ concentration of 3.6 mM, enabling its high accumulation within the cells, while not negatively affecting biomass yield was selected for further studies. Iron uptake led to the modifications in transport of several other elements (Ca2+, Zn2+, K+ and Na+) and thus to the change in ion composition of the cells in comparison with the corresponding control.

Establishing the correspondence between control points in pairs of mammographic images.

This paper describes part of a study aimed at developing a computer-based aid for mammogram screening that makes a detailed comparison between mammograms of the same patient acquired at different screenings and detects changes indicative of cancer. The focus is on determining control points in two mammograms; these points are used to put two mammograms into correspondence. The paper details the algorithm for identifying the potential control points and establishing the correspondence between the two sets of control points. The algorithm's performance was evaluated by three observers, one of whom is an experienced radiologist, and found to be adequate.