PubMed · 4844295
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S N Efuni, T N Giorgobiani, L A Sergeev. 1974. Hyperbaric oxygenation center.. https://doi.org/10.1007/bf00557577
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An apparatus was developed to apply positive or negative hydrostatic pressure dynamically to periodontal ligament (PDL) cells in vitro. The objective of this investigation was to construct this apparatus and to determine its effects on PDL cells. Human PDL cells were collected from freshly extracted premolars. At the sixth passage, the cells were mechanically stimulated by this apparatus at different magnitudes of continuous positive or negative hydrostatic pressures (PHP or NHP, respectively). The application of PHP between 0.3 and 30 gm/cm2 significantly enhanced prostaglandin E (PGE) production and intracellular cyclic AMP (cAMP) of the cells. In contrast, perturbation by NHP significantly decreased PGE production and intracellular level of cAMP. Proliferation rate increased significantly at 24 and 48 hours due to stimulation of these cells with -30 gm/cm2 of NHP. Challenging these cells with +30 gm/cm2 of PHP significantly decreased the proliferation rate of these cells at 24 and 48 hours. Stimulation by PHP between +30 to +600 gm/cm2 increased cell length and width and appeared to increase surface area attachment to the bottom of the culture dishes. In contrast, NHP (between -30 and -600 gm/cm2) decreased these dimensions and appeared to reduce the surface area of attachment. These results indicate that this type of mechanical perturbation of PDL cells produces physiologic responses and is not detrimental to their vitality.
A method for vapor-dosing of charcoal sorbent tubes (CST) that does not require the expense and effort of a test chamber was used to test the desorption efficiency (DE) of seven solvent vapors, representing six classes of solvents as follows: aromatic hydrocarbons (m-xylene); ether/alcohol (2-ethoxyethanol); vinyl monomers (styrene monomer, vinyl acetate); aliphatic hydrocarbons (n-hexane); aliphatic esters (n-butyl acetate); and aliphatic acrylic monomers (methyl methacrylate). The quantities of the solvents used in these experiments would represent eight-hour exposures to concentrations of approximately 0.2 to 10 ppm. The vapor-dosing experimental system consisted of a loaded filter cassette connected directly to a CST. Vapor was generated by injecting liquid solvent onto the glass fiber filter and drawing air through the system. The solvent was desorbed from the filter and charcoal for analysis. Vapor desorption efficiency was determined from the fraction of the injected solvent evaporated from the filter and the amount recovered from the charcoal. The measured DEs were similar to those reported for liquid dosed charcoal. Vapor dosing of sorbent tubes is more representative of samples collected for industrial hygiene exposure assessment. The system is simple to use and applicable for vapor dosing of any sorbent tube.
The Oxoid AnaeroGen system was compared with the BBL GasPak for the production of an anaerobic atmosphere and was evaluated for its ability to support the growth of 135 clinically significant anaerobic bacteria. An anaerobe chamber was used as the "gold standard" for supporting the growth of anaerobes. The AnaeroGen requires no catalyst, produces no hydrogen, requires no water, and reduces preparation time to a minimum. The water-activated BBL GasPak generates hydrogen. For 132 of the 135 strains tested, better initial growth at 48 h was noted for the jar methods than for the anaerobe chamber. At 72 h, 113 of the 135 strains showed equal growth, and at 7 days, only marginal differences in growth patterns were noted. The AnaeroGen never failed to reduce the anaerobic indicator, while the BBL GasPak occasionally failed to do so. The AnaeroGen performed at least as well as, and sometimes better than, the established methods. The AnaeroGen is a good alternative for use in anaerobic jars.