High-pressure liquid chromatographic identification of drugs used in management of arthritis

A screening procedure was developed for the identification of drugs used in the clinical treatment of arthritis. Each glucocorticoid, nonsteroidal anti-inflammatory agent, or tranquilizer was characterized by its retention on a reversed-phase high-pressure liquid chromatographic column and by the ratio of the response of dual UV detectors (254 and 280 nm). Although the retention times of all 14 drugs examined were less than 4 min. each drug could be distinguished easily from the other drugs in the series.     

Measurement of carbon-14 and tritium in the effluent of a gas chromatography column

Several methods of measuring radioactivity in the effluent of a gas-liquid chromatography (GLC) column are reviewed. If there is sufficient radioactivity in individual compounds to be measurable with acceptable precision in less than 15–20 see, the effluent of a GLC column can be assayed for radioactivity during the course of an analysis. The effluent can be passed directly through a heated ionization chamber or proportional counter but both of these are some-what sensitive to changes in the composition of the gas. The effluent can also be combusted to carbon dioxide and water, and the water then converted to HT for tritium assay. These gases can then be assayed in an ionization chamber, proportional counter or flow-through scintillation counter at ambient temperature. The detector volume and gas flow rate can then be large so that changes in gas composition that occur during the course of an analysis are minimized. The gas flow is adjusted for optimal speed of response. Combustion trains have been developed that minimize memory effects in tritium assays that otherwise can cause difficulties. Convenient calibration methods are available for setting up the methods and for determining their efficiencies. When there is insufficient radioactivity in the sample to be measurable during a short time interval, the effluent can be fractionated, high boiling material in each fraction can be condensed out and assayed for radioactivity for longer periods. Automatic and quantitative fraction collecting devices have been developed for use with liquid scintillation counters that make this method of radioassay accurate as well as highly sensitive.     

Bacterial population in counter flow and parallel flow water chilling of poultry meat

In this study, a survey was carried out to determine the hygiene aspects of counter flow and parallel flow water chilling of poultry meat. Samples were taken in five sectors: in the sector subsequent to evisceration of the poultry, in the sector after water chilling, and in the sector after final washing. At the same time, the samples of water were taken from the pre-chilling sector and in the chilling sector. Bacterial detection of the inherence of various bacteria, their isolation, identification and determination was carried out. The results showed higher numbers of positive samples obtained from the section of water chilling in comparison to other sections, as well as a higher number of positive samples in the process of parallel flow water chilling in comparison to the results from counter flow chilling.     

Toxicological Aspects of Long‐Term Treatment of Keratinocytes with ZnO and TiO2 Nanoparticles

Sunscreens containing ZnO and TiO₂ nanoparticles (NPs) are increasingly applied to skin over long time periods to reduce the risk of skin cancer. However, long‐term toxicological studies of NPs are very sparse. The in vitro toxicity of ZnO and TiO₂ NPs on keratinocytes over short‐ and long‐term applications is reported. The effects studied are intracellular formation of radicals, alterations in cell morphology, mitochondrial activity, and cell‐cycle distribution. Cellular response depends on the type of NP, concentration, and exposure time. ZnO NPs have more pronounced adverse effects on keratinocytes than TiO₂. TiO₂ has no effect on cell viability up to 100 μg mL^?1, whereas ZnO reduces viability above 15 μg mL^?1 after short‐term exposure. Prolonged exposure to ZnO NPs at 10 μg mL^?1 results in decreased mitochondrial activity, loss of normal cell morphology, and disturbances in cell‐cycle distribution. From this point of view TiO₂ has no harmful effect. More nanotubular intercellular structures are observed in keratinocytes exposed to either type of NP than in untreated cells. This observation may indicate cellular transformation from normal to tumor cells due to NP treatment. Transmission electron microscopy images show NPs in vesicles within the cell cytoplasm, particularly in early and late endosomes and amphisomes. Contrary to insoluble TiO₂, partially soluble ZnO stimulates generation of reactive oxygen species to swamp the cell redox defense system thus initiating the death processes, seen also in cell‐cycle distribution and fluorescence imaging. Long‐term exposure to NPs has adverse effects on human keratinocytes in vitro, which indicates a potential health risk.     

LOVA Propellant Aging: Effect of Residual Solvent

An investigation of LOVA propellant aging was performed to identify the cause of stabilization periods in certain propellant lots. Two important observations were made: (1) the level of residual solvent in propellant grains slowly decrease while in storage, and (2) during the drying process and while the grains are in storage, plasticizer “co-migrates” with solvent, resulting in plasticizer accumulation at grain surfaces. It was also observed that while in storage, residual solvent may be oxidized to generate organic acids. Based on these results, it is proposed that stabilization periods result from processes related to migration, evaporation, and oxidation of residual solvent.