Development of high temperature comprehensive two-dimensional liquid chromatography hyphenated with infrared and light scattering detectors for characterization of chemical composition and molecular weight heterogeneities in polyolefin copolymers.

The application of high temperature comprehensive two-dimensional (2D) liquid chromatography for quantitative characterization of chemical composition and molecular weight (MW) heterogeneities in polyolefins is demonstrated in this study by separating a physical blend of isotactic-polypropylene, ethylene-random-propylene copolymer, and high density polyethylene. The first dimension separation is based on adsorption liquid chromatography that fractionates the blend from low to high ethylene content. The second dimension is size-exclusion chromatography connected with light scattering (LS) and infrared (IR) detectors. The IR detector shows desired sensitivity and linearity for monitoring analyte concentrations in the eluent after 2D separations. In addition, the compositions of the analytes are also determined from the ratio of two IR absorbances at the specified wavelength regions, an absorbance for measuring the level of methyl groups in polyolefins and another absorbance for measuring concentration. The LS detector is used to determine absolute molecular weight of the analytes from the ratio of the light scattering signal to the IR concentration signal. The ability to obtain concentration, chemical composition, and MW of polyolefins after 2D separation provides new opportunities to discover structure-property relationships for polyolefins with complex structures/architectures.

Fate and transport of zoonotic, bacterial, viral, and parasitic pathogens during swine manure treatment, storage, and land application.

Members of the public are always somewhat aware of foodborne and other zoonotic pathogens; however, recent illnesses traced to produce and the emergence of pandemic H1N1 influenza virus have increased the scrutiny on all areas of food production. The Council for Agricultural Science and Technology has recently published a comprehensive review of the fate and transport of zoonotic pathogens that can be associated with swine manure. The majority of microbes in swine manure are not zoonotic, but several bacterial, viral, and parasitic pathogens have been detected. Awareness of the potential zoonotic pathogens in swine manure and how treatment, storage, and handling affect their survival and their potential to persist in the environment is critical to ensure that producers and consumers are not at risk. This review discusses the primary zoonotic pathogens associated with swine manure, including bacteria, viruses, and parasites, as well as their fate and transport. Because the ecology of microbes in swine waste is still poorly described, several recommendations for future research are made to better understand and reduce human health risks. These recommendations include examination of environmental and ecological conditions that contribute to off-farm transport and development of quantitative risk assessments.

Placental cell release of transferrin: analysis by reverse haemolytic plaque assay.

Recent demonstrations of transferrin (TF) mRNA in placental tissue raised the possibility that the placenta may serve as an extra-hepatic source of this iron-binding protein during development. In this study, we first confirmed these findings using cRNA probes for TF, and then adapted the TF reverse haemolytic plaque assay for use with rat placental cells to identify the location and functional characteristics of cells secreting this product. We found TF releasing cells in placentae (day 19-21) with greater proportions present in cultures from basal than labyrinth zone regions. These cells appeared quite stable as evidenced by observations that fresh populations and 24, 48 and 72 h cultures from the same placental regions all contained similar percentages of secretors. The rate of TF plaque formation was greatly enhanced in the presence of tumour necrosis factor (0.1 ng/ml) for basal zone and yolk sac cells, but not for labyrinth zone cells, suggesting a potent but regionally specific modulation of TF release. When taken together, these findings demonstrate clearly that TF is released from cells of the placenta. Moreover, the regional differences in frequency and modulation of these cells suggests that the release of placental TF is a dynamic and carefully controlled process.

Sertoli cell function varies along the seminiferous tubule: the proportion and response of transferrin secretors differ between stage-associated tubule segments.

Recent studies from our laboratory demonstrated clearly that only a portion of all Sertoli cells secrete transferrin (TF). These findings raised the possibility that differences in the functional type of Sertoli cells from one location to another may account in part for the stage-related variation in TF release along the seminiferous tubule. In order to address this, Sertoli cells derived from tubule segments corresponding to stages III-V, VII, IX-XI, and XIII of the seminiferous epithelial cycle were subjected to reverse hemolytic plaque assays to determine whether the proportion of TF cells present in those segments were similar or different. We found 21.4 +/- 1.8%, 20.3 +/- 2.0%, 48.3 +/- 2.5%, and 49.2 +/- 3.2% of all cells secreted TF in III-V, VII, IX-XI, and XIII staged segments, respectively. Results obtained from immunocytochemical staining of cells from different sections agreed well with those obtained with plaque assays, indicating that we had detected most, if not all, TF cells in these cultures. In additional experiments, we found that cultured cells from stage III-V and VII responded to FSH or isoproterenol with a large increase in the rate of TF plaque formation, whereas cells from IX-XI and XIII segments appeared to be unaffected. In contrast, bovine fibroblast growth factor caused a marked increase in the rate of TF plaque formation with IX-XI cells and only a slight increase with cells from III-V staged segments. Thus, the manner in which Sertoli cells respond to several modulatory agents appears not only to be stage-dependent, but also to be specific to the agent in question. When taken together, our observations demonstrate that cultured TF secretors obtained from different staged segments of the seminiferous tubule differ in proportion and responsiveness. These findings, when viewed in light of reports of a constant number of Sertoli cells along the seminiferous tubule, suggest that Sertoli cells may acquire and lose the ability to secrete TF or respond to modulation as the seminiferous cycle progresses.

Physiological effects of 1,3-butanediol fed to cattle.

In four trials with growing cattle we observed effects of 1,3-butanediol on rumen fermentation end products, blood components, growth rates, feed efficiency, and body composition. Diets A and C contained 80% grain: 20% alfalfa pellets and 40% grain: 60% alfalfa pellets; in diets B and D, 1,3-butanediol replaced 4% of diets A and C. Feeding 4% 1,3-butanediol caused no significant differences in rumen pH, volatile fatty acid ratios, blood glucose, or blood ketones. Cattle fed 4% 1,3-butanediol had rates of gain and feed efficiency equivalent to and often better than cattle fed the same diet without butanediol. Body composition was not affected by feeding 4% 1,3-butanediol. Results indicate 4% 1,3-butanediol can be fed to cattle without adverse physiological effects and may improve performance. When 6% or more 1,3-butanediol was fed, blood ketones were elevated considerably, animals were hyperactive, gained less weight, and feed efficiency was lower.