Dynamic properties of Na+ ions in models of ion channels: a molecular dynamics study

We present simulation results for the effective diffusion coefficients of a sodium ion in a series of model ion channels of different diameters and hydrophobicities, including models of alamethicin, a leucine-serine peptide, and the M2 helix bundle of the nicotinic acetylcholine receptor. The diffusion coefficient, which in the simulations has a value of 0.15(2) A2ps-1 in bulk water, is found to be reduced to as little as 0.02(1) A2ps-1 in the narrower channels, and to about 0.10(5) A2ps-1 in wider channels such as the nicotinic acetylcholine receptor. It is anticipated that this work will be useful in connection with calculations of channel conductivity using such techniques as the Poisson-Nernst-Planck equation, Eyring rate theory, or Brownian dynamics.     

A vaccine consisting of recombinant Borrelia burgdorferi outer-surface protein A to prevent Lyme disease. Recombinant Outer-Surface Protein A Lyme Disease Vaccine Study Consortium

The purpose of this study was to determine whether infrared tympanic membrane thermometry can replace mercury-in-glass temperatures as an assessment tool for detecting fevers earlier and more reliably in a pediatric oncology outpatient setting. A total of 313 patient visits had infrared tympanic temperatures (obtained by using the LighTouch LTX Pedi-Q thermometer (Exergen; Watertown, MA) and axillary temperatures taken simultaneously (obtained by using mercury-in-glass thermometers). Those patients with a normal axillary temperature and an elevated tympanic measurement of 38 degrees C or higher had a follow-up axillary temperature conducted that evening to determine whether an elevated tympanic temperature predicted on coming fever or infection. The mean tympanic temperature was 37.5 degrees C and the mean axillary temperature was 36.8 degrees C, a difference of 0.7 degree C (P = .0001). Sixty-two (20%) patients had discrepant temperatures with a febrile tympanic and normal axillary measurement. Three (5%) of these patients were febrile at their follow-up axillary reading. Tympanic thermometry resulted in a significantly higher temperature reading than the axillary method. Elevated tympanic temperatures were not predictive of oncoming fever or infection. Fevers were not missed when using the tympanic method. To prevent unnecessary medical intervention, it is recommended that mercury-in-glass thermometers verify elevated tympanic temperatures.