Study of the dynamics of poly(ethylene oxide) by combining molecular dynamic simulations and neutron scattering experiments.

We performed quasielastic neutron scattering experiments and atomistic molecular dynamics simulations on a poly(ethylene oxide) (PEO) homopolymer system above the melting point. The excellent agreement found between both sets of data, together with a successful comparison with literature diffraction results, validates the condensed-phase optimized molecular potentials for atomistic simulation studies (COMPASS) force field used to produce our dynamic runs and gives support to their further analysis. This provided direct information on magnitudes which are not accessible from experiments such as the radial probability distribution functions of specific atoms at different times and their moments. The results of our simulations on the H-motions and different experiments indicate that in the high-temperature range investigated the dynamics is Rouse-like for Q-values below approximately 0.6 A(-1). We then addressed the single chain dynamic structure factor with the simulations. A mode analysis, not possible directly experimentally, reveals the limits of applicability of the Rouse model to PEO. We discuss the possible origins for the observed deviations.

Age-related changes in serum chemistry and hematology values in normal Sprague-Dawley rats.

Age-related changes in serum chemistry and hematology values in male and female Sprague-Dawley rats 2 to 29 months of age are described. The number of values per determination (N) ranged from 554 to 1126. Serum chemistry parameters demonstrating changes with time included inorganic phosphorus, total protein, cholesterol, triglycerides, and alkaline phosphatase. There was little or no sex difference among these parameters. Hematologic parameters demonstrating changes with time included leukocyte elements (lymphocytes, neutrophils, eosinophils, monocytes), erythrocyte parameters (red blood cell count, hematocrit, hemoglobin, mean cell volume, mean cell hemoglobin), and platelet count. Most trends in erythrocyte parameters were more marked in males than in females. To visualize the effect of age of these parameters, the data were plotted vs time, and fitted models were superimposed on the graphs. Comparisons with available literature values are made, and the value of an age-related data base when conducting long-term toxicity studies is discussed.

Reference range data base for serum chemistry and hematology values in laboratory animals.

A reference range data base containing serum chemistry and hematology values on over 3000 animals is described. Data listed include the mean, standard deviation, and 10th and 90th percentiles for each of the following parameters. Serum chemistry: sodium, potassium, chloride, calcium, inorganic phosphorus, urea nitrogen, creatinine, total bilirubin, total protein, glucose, cholesterol, triglycerides, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyltransferase (monkey only), lactate dehydrogenase (dog only), and creatine kinase (dog only). Hematology: hematocrit, hemoglobin, red blood cells, reticulocytes, mean cell volume, mean cell hemoglobin, mean cell hemoglobin percent, platelets, white blood cells, neutrophils, eosinophils, basophils, lymphocytes, monocytes, and stabs. The species included are mouse, rat, hamster, rabbit, beagle dog, and cynomolgus monkey. The use of the reference ranges in routine computerized data collection is discussed.

The LEDTOX Necropsy System: an interactive protocol driven gross postmortem examination data collection system.

The LEDTOX Necropsy System consists of a series of programs which provide for the real time collection of gross postmortem data while interacting with the LEDTOX Protocol, Animal Weighing/Clinical Observation, Palpable Mass, Clinical Pathology, Histopathology and Animal Colony Management Systems. Special procedures and lists of tissues specified in the protocol for various necropsy activities drive to data collection routines. Key system features include: system generated gross findings menu to facilitate data entry; designation of key phrases to be used for data summarization; online confirmation of palpable masses identified during life; online review of clinical observation and clinical pathology data. Outputs include: incidence summary of gross postmortem findings; tissue examination/sampling summary; correlation of antemortem and postmortem mass/neoplasm data; organ weight statistical summary. With completion of this module, 90-100% of the routine tables for postmortem reports are immediately available to pathologists for data interpretation.