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Biomedical subjects

J Shinn

Publications and source records attributed to J Shinn.

5 recordsLinked to original sources

Pneumoparotid due to spirometry.

Pneumoparotid has been described in patients who generate increased intraoral pressures when playing wind instruments, while coughing, and when undergoing dental work. Some patients have intentionally created pneumoparotid to avoid duties at school or in the military, or to gain attention. We describe a patient who developed pneumoparotid during pulmonary function testing. The diagnosis of pneumoparotid depends on a suggestive clinical situation and glandular swelling with or without crepitus. Observation of aerated saliva per Stensen's duct or air in the parotid duct and/or gland by any imaging study is diagnostic if infection with a gas-forming organism can be reasonably excluded. No specific treatment is required, other than the avoidance of predisposing activities.

Adult↗

Biological effectiveness of high-energy protons: target fragmentation.

High-energy protons traversing tissue produce local sources of high-linear-energy-transfer (LET) ions through nuclear fragmentation. We examine the contribution of these target fragments to the biological effectiveness of high-energy protons using the cellular track model. The effects of secondary ions are treated in terms of the production collision density using energy-dependent parameters from a high-energy fragmentation model. Calculations for mammalian cell cultures show that at high dose, at which intertrack effects become important, protons deliver damage similar to that produced by gamma rays, and with fragmentation the relative biological effectiveness (RBE) of protons increases moderately from unity. At low dose, where sublethal damage is unimportant, the contribution from target fragments dominates, causing the proton effectiveness to be very different from that of gamma rays with a strongly fluence-dependent RBE. At high energies, the nuclear fragmentation cross sections become independent of energy. This leads to a plateau in the proton single-particle-action cross section, below 1 keV/micron, since the target fragments dominate.

Cell Survival↗

Innervated temporal-muscle mastoid flaps.

Histological comparisons have been made of predicted temporal-muscle flaps with and without an intact nerve supply. The viability of the musculoplasty depends on maintenance of the neural bundle.

Animals↗