Biomedical subjects
Publications and source records attributed to L E Ford.
Free calcium appears to trigger the release of stored calcium from the sarcoplasmic reticulum of skinned skeletal muscle fibers immersed in solutions with a low concentration of magnesium ion.
A method for isolating plasma membrane fragments from HeLa cells is described. The procedure starts with the preparation of cell membrane "ghosts," obtained by gentle rupture of hypotonically swollen cells, evacuation of most of the cell contents by repeated washing, and isolation of the ghosts on a discontinuous sucrose density gradient. The ghosts are then treated by minimal sonication (5 sec) at pH 8.6, which causes the ghost membranes to pinch off into small vesicles but leaves any remaining larger intracellular particulates intact and separable by differential centrifugation. The ghost membrane vesicles are then subjected to isopycnic centrifugation on a 20-50% w/w continuous sucrose gradient in tris-magnesium buffer, pH 8.6. A band of morphologically homogeneous smooth vesicles, derived principally from plasma membrane, is recovered at 30-33% (peak density = 1.137). The plasma membrane fraction contained a Na-K-activated ATPase activity of 1.5 micromole Pi/hr per mg, 3% RNA, and 13.8% of the NADH-cytochrome c reductase activity of a heavier fraction from the same gradient which contained mitochondria and rough endoplasmic vesicles. The plasma membranes of viable HeLa cells were marked with (125)I-labeled horse antibody and followed through the isolation procedure. The specific antibody binding of the plasma membrane vesicle fraction was increased 49-fold over that of the original whole cells.
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The outpatient treatment of heart failure can be divided into 2 broad categories: older therapies, which improve hemodynamics, and newer therapies, which increase survival and improve function. Hemodynamic "triple" therapy includes digoxin to increase cardiac inotropy, antihypertensives to lower systolic pressure, and diuretics to remove fluid and decrease filling pressures. Disease-modifying therapy requires the use of specific agents to lower blood pressure (angiotensin-converting enzyme inhibitors, angiotensin II blockers, spironolactone, or hydralazine and nitrates) and beta-adrenergic blockade with carvedilol. The success of these newer therapies suggests that the standard triple therapy for heart failure should be expanded to "quadruple" therapy that includes carvedilol.