A theoretical analysis was used to evaluate the effect of body mass on the mechanical power cost of cross-country skiing and roller skiing on flat terrain. The relationships between body mass and the power cost of overcoming friction were found to be different between cross-country skiing on snow and roller skiing. Nevertheless, it was predicted that the heavier skier should have a lower oxygen cost per unit of body mass for roller skiing, as is the case for snow skiing. To determine whether the theoretical analysis was supported by experimental data, oxygen consumption measurements were performed during roller skiing by six male cross-country ski racers who spanned a 17.3-kg range in body mass. The theoretical analysis was supported by the experimental findings of decreases in oxygen consumption for each kg increase in body mass of approximately 1.0% for the double pole technique, 1.8% for the kick double pole technique, and 0.6% for the VI skate technique.

Bacterial endotoxins or lipopolysaccharides (LPS), cell wall components of gram-negative bacteria, are involved in septic shock. LPS consists of a lipid A tail attached to core and O-antigen polysaccharides, but little is known about the supramolecular structure of LPS in blood. We have developed an approach to locate donor and acceptor probes in sulfobetaine palmitate detergent micelles using steady-state and time-resolved fluorescence resonance energy transfer. C18-fluorescein and several LPS species of varying molecular weight labeled with fluorescein isothiocyanate (FITC-LPS) were the donor probes. Acceptor probes were 1,1-dilinoleyl-3,3,3',3'-tetramethyl indocarbocyanine perchlorate (Fast C18-Dil, Ro approximately 68 A), and octadecyl B rhodamine chloride (C18-Rhd, Ro approximately 58 A). With either acceptor, the transfer was of similar high efficiency when FITC-LPS Salmonella minnesota Re 595 (2,500 mol wt, lacking both core and O-antigen) or C18-fluorescein were the fluorescent donor probes. Thus, the donor FITC-LPS with short polysaccharide chain S. minnesota Re 595 and the control donor C18-fluorescein appear to be close to the micelle surface. The transfer efficiency decreased as the molecular weight of the LPS increased. Separation distances between the longest FITC-LPS, S. minnesota (20,000 mol wt, with a long O-antigen), and the micelle were estimated to be 1.5 Ro or more (approximately 100 A), consistent with an extended conformation for the longer O-antigen polysaccharide chain in the detergent.

Fluorescence resonance energy transfer (FRET) measurements have been used to analyze fluorophore separations in a number of varying geometries, including small particles and extended surfaces. This study focuses on the geometry created by a donor extended above the surface of a small sphere (radius < R0), where the acceptors are integrated into the sphere surface. The model of this geometry was based on an amphipathic molecule with its lipophilic region integrated into a detergent micelle and its hydrophilic region extending outward from the micelle surface, where the donor fluorophore is attached to the hydrophilic region of the molecule. Based on random acceptor incorporation into the micelle, a Poisson distribution was used to calculate the distribution of acceptor probes across the micelle population. The model converges to RET on a flat surface when the radius of the micelle exceeds 0.8 R0. The model was also used to simulate FRET data showing that the positions of donors above the micelle surface could be uniquely resolved. Experimental verification of the model was achieved in a sulfobetaine palmitate micelle with fluorescein isothiocyanate donors attached to detergent-solubilized lipopolysaccharide (LPS) and lipophilic Fast-DiI acceptors. The use of steady-state analysis allowed resolution of cases in which donors were located at different distances from the surface. Combining steady-state with excited-state lifetime analysis allowed resolution of cases where there was a combination of distances. Given the large number of biomolecules that interact with lipids, this approach may prove generally useful for defining molecular conformation.

Whole-head magnetoencephalographic (MEG) data were collected from a 33-year-old male who was diagnosed at 6 years of age with autism. Childhood symptoms included acquired aphasia, self-stimulatory behavior, poor Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Email this article to a Colleague Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to My Articles & Searches Download to citation manager Citing Articles via HighWire Citing Articles via Google Scholar Articles by Hurley, R. A. Articles by Taber, K. H.

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