Familial syndrome of midsystolic click and late systolic murmur

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Variations in sulfhydryl, disulfide, and protein content during synchronous and asynchronous growth of HeLa cells

The cellular contents of protein-bound and nonprotein sulfhydry (-SH) and disulfide (-SS-) groups were measured in both asynchronous and synchronous HeLa S3 cultures. About 90% of these groups are associated with proteins, the majority in the -SH form. The content of protein-bound groups, and hence the total content of -SH and -SS- groups (28 x 10(-15) moles/cell, or 1.1 x 10(-6) moles/g protein on average), changes in parallel with the protein content (which varies between 2 and 4 x 10(-10) g/cell) as asynchronous populations pass from the lag through the exponential to the stationary phase of growth. The concentration of nonprotein -SH groups, in contrast, increases 10-fold during lag phase and decreases in stationary phase; it follows the protein concentration closely during the exponential phase, at a level of about 2.8 x 10(-15) moles/cell. In synchronous cultures the protein content doubles during the cell cycle, possibly in an exponential fashion. The total -SH and -SS- content also doubles, but the rate of increase appears to fluctuate. The concentrations of the protein-bound groups show 2- to 3-fold fluctuations per unit protein: protein-bound -SH groups and mixed -SS- linkages rise to maxima while protein-bound -SS- groups fall to a minimum at the G(1)/S transition, and fluctuations in these groups occur again during G(2). In addition, the protein-bound -SH concentration falls continuously during the S phase. The nonprotein -SH concentration undergoes the largest (relative) fluctuations, dropping from 4 x 10(-15)moles/cell in early G(1) to about 0.4 x 10(-15) moles/cell (of standard protein content) at the end of G(1), and then rising to 30 times this value by the end of S.

Age response to x-radiation of murine lymphoma cells synchronized in vivo

Cells of a transplantable murine lymphoma line were partially synchronized in vivo by administration of a single dose of 0.5 mg of hydroxyurea per lymphoma-bearing mouse. At various times after administration of hydroxyurea, the femurs of the lymphomatous mice were X-irradiated, and the number of lymphoma colony-forming units per femur were then assayed by the spleencolony technique. A well-defined age response to irradiation of the lymphoma cells in vivo, similar to that of HeLa cells in vitro, was observed.

Sulfur mustard and x-rays: differences in expression of lethal damage

Before or after treatment with sulfur mustard, simple changes in the incubation conditions of cultured Chinese hamster cells lead to changes as great as a factor of 6 in survival-curve slopes. With x-ray treatment, changes are similar but much smaller in magnitude. These results suggest that the modes of action of these agents are not entirely the same.