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E Bradley

Publications and source records attributed to E Bradley.

9 recordsLinked to original sources

Transformation of human cells by temperature-sensitive mutants of simian virus-40.

Conditions necessary for the establishment and maintenance of transformation of human cells by wild type and temperature-sensitive mutants of SV40 were examined. For both early and late mutants, the frequency of transformation was found to be up to 5-fold higher, and virus yield 100-fold lower, at 39 degrees than at 33 degrees. No such effect was observed with the wild type virus under the same conditions. This observation is apparently at variance with previously published work, but may be explained by the semipermissive nature of the cells that we used. Increasing the temperature to 40.5 degrees caused cells transformed by the early mutant, tsA30, to lose T-antigen as detectable by staining, and also to lose the ability to grow to high density, while it produced no effect on cells transformed by wild type virus.

Antigens, Neoplasm

Effects of bicarbonate on remineralization of enamel.

Enamel surfaces were demineralized in acetic acid and remineralized in solutions that contained 1.5 mM calcium, 1.0 mM phosphate, and 0.0, 5, 15, and 25 mM NaHCO3, and 0.00 or 5.0 mM Naf at pH 7.0. NaF in CO2-free solutions increased the rates of calcium and phosphate uptake during remineralization. Bicarbonate in NaF-free solutions caused small increases of calcium and phosphate uptake. Bicarbonate with NaF in solutions synergistically increased calcium uptake, but did not affect phosphate uptake. Bicarbonate reduced fluoride uptake by about 50% during remineralization, and increased the Ca/P ratios of deposited minerals from about 1 (dicalcium phosphate) to approach and exceed the ratios of apatites.

Animals

Measurement of bone density by gas displacement.

Small bone volumes, porous and irregular structured objects with volumes 0.05-2 cm3, were measured by differential pressure of displaced air. The differential air pressure was measured by a piezoelectric resistor pressure gauge. The gas-displacement system was used to measure the volumes of 234 bone specimens for calculation of bone density. The operation of the system, calibration, sensitivity, and errors of measurement are described.

Animals