Biomedical subjects
Publications and source records attributed to P E Levin.
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The influence of an extremely low frequency (ELF) electric field stimulus (30 Hz at 6 microV/cm rms), known to promote bone formation in vivo, was evaluated for its ability to affect bone cell function in vitro. To accomplish this, we developed an apparatus for the exposure of monolayer cell systems to electric fields in a manner that provides relatively uniform electric field exposure of multiple cell samples as well as a rigorous sham exposure. We show that field exposure significantly limits the normal increase in osteoblastic cell number and enhances alkaline phosphatase activity compared to sham-exposed samples. Moreover, these alterations are shown to occur in a cell density-dependent manner. Samples plated at 6 x 10(3) cells/cm2 show no effect of field exposure. In samples plated at 30 x 10(3) cells/cm2, 72 h of field exposure resulted in 25% fewer cells in the exposed samples, and a doubling of alkaline phosphatase activity in those cells compared to sham exposure. Experiments using a 12 h exposure to preclude significant changes in cell number during the exposure show this density-dependent response to be biphasic. Sparse cultures (< 50 x 10(3) cells/cm2) were not found to be affected by the field exposure, but increases in alkaline phosphatase activity occurred in cultures at densities of 50-200 x 10(3) and 200-350 x 10(3) cells/cm2 and no effect on alkaline phosphatase activity was seen in confluent cell cultures of greater than 350 x 10(3) cells/cm2.(ABSTRACT TRUNCATED AT 250 WORDS)
During interlocking intramedullary nailing of twenty-five femoral and five tibial fractures, the primary surgeon wore both a universal film badge on the collar of the lead apron and a thermoluminescent dosimeter ring on the dominant hand to quantify the radiation that he or she received. When distal interlocking was performed, the first ring was removed and a second ring was used so that a separate recording could be made for this portion of the procedure. At the conclusion of the study, all of the recorded doses of radiation were averaged. The average amount of radiation to the head and neck during the entire procedure was 7.0 millirems of deep exposure and 8.0 millirems of shallow exposure. The average dose of radiation to the dominant hand during insertion of the intramedullary nail and the proximal interlocking screw was 13.0 millirems, while the average amount during insertion of the distal interlocking nail was 12.0 millirems. Both of these averages are well within the government guidelines for allowable exposure to radiation during one-quarter (three months) of a year. Precautions that are to be observed during this procedure are recommended.