Retrospective analysis of Naval Special Boards of Flight Surgeons, 1974-83

The Naval Special Board of Flight Surgeons was established in 1956 for the evaluation of Navy, Marine Corps, and Coast Guard problem aeromedical cases. This paper examines a sample 248 of these cases for the period of 1974-83 with respect to the characteristics of those referred, their referral diagnostic category, and the recommendation of the Special Board regarding return to a flying status. Those cases with a referral diagnostic category of ENT and Ophthalmology were less likely to be returned to flight status. Older, more senior pilots, and pilots with more total flight time were less likely to be returned to unrestricted flying than were their younger, more junior, and less experienced counterparts. Otherwise, no significant difference in outcome based on age, rank, marital status, branch of service, specialty, or flight hours was detected. Overall, 61% of those evaluated by the SBFS were returned to flight status.     

FM sonography in diffuse liver disease: prospective assessment and blinded analysis

FM sonography - a signal-processing technique that uses frequency and phase information as well as amplitude data - shows promise in evaluation of patients with diffuse liver disease. In a prospective blinded review of 37 patients with biopsy-proved liver disease and 42 healthy volunteers, FM sonography was clearly superior to traditional amplitude-based (AM) sonography in distinguishing healthy from diseased subjects. Statistically significant differences were seen in accuracy (FM, 98.7%; AM, 84.8%), sensitivity (FM, 97.3%; AM, 70.3%), and negative predictive value (FM, 97.7%; AM, 78.8%). Our data also suggest that current FM sonographic techniques cannot differentiate among histologic findings associated with different hepatic parenchymal abnormalities. It is unclear, therefore, whether FM imaging can reduce the numbers of patients who require biopsy for diagnosis or the frequency of biopsy procedures in patients with known disease.     

Alteration in myelin-associated proteins following spinal cord irradiation in guinea pigs.

The aim of this study was to investigate the pathological and cellular basis for radiation-induced myelopathy in guinea pigs by monitoring biochemical alterations in levels of myelin basic protein and 2',3'-cyclic nucleotide phosphohydrolase. Guinea pigs were irradiated to the lumbar region with various doses of neutrons or cobalt gamma irradiation. The ED50s for paralysis were 17.2 Gy and 67.5 Gy for neutron and cobalt irradiation, respectively, and was histologically associated with demyelination. In spinal cords taken from animals at the onset of paralysis myelin basic protein levels were decreased in direct relationship to the radiation dose. The lowest doses to cause paralysis led to a 25% decrease in MBP levels. In a separate experiment, alterations in MBP were measured in the spinal cords over the time period leading up to paralysis. Surprisingly, decreases in MBP were found immediately after the end of the 4 week irradiation period. These early changes in MBP were not markedly dose dependent and occurred with nonparalyzing doses. Dose-dependent decreases were found only just before the onset of paralysis. CNPase activity measured in the same specimens showed changes that were essentially similar to those for MBP. In the CSF, MBP levels were essentially constant until onset of paralysis. This study showed that demyelination, as assessed by the levels of the myelin-associated proteins MBP and CNPase, can occur soon after spinal cord irradiation but that profound dose-dependent changes are seen only immediately preceding the onset of paralysis. Although increases in MBP in the CSF were associated with the onset of radiation-induced myelopathy, its assay is unlikely to predict this complication of irradiation.