Regulation of acetylcholine synthesis: does cytoplasmic acetylcholine control high affinity choline uptake?

When brain synaptosomes are obtained from animals that have been injected intravenously with [2H4]choline 1 minute before being killed, their high affinity [3H] choline uptake is correlated inversely with their acetylcholine content and directly with the rate at which they synthesize [2H4]acetylcholine. The control of such choline uptake by the cytoplasmic acetylcholine concentration is proposed as a mechanism regulating acetylcholine synthesis in cholinergic nerve terminals.     

Aerial fallout of DDT in southern California

Ender's method of intramedullary fixation of intertrochanteric and subtrochanteric fractures is described. Ender's nail is a pre-bent flexible steel nail with a diameter of 4.5 millimeters. Three to five of these nails are inserted from a small incision proximal to the medial epicondyle of the femur into the medullary canal. They are passed through the femur across the fracture site and into the head of the femur, where they diverage. They are in the lines of force and therefore are not subjected to bending moments. The fracture fixation allows immediate weight-bearing. This method of fixation was used in a series of 203 patients. Their average age was sixty-eight years; the mortality rate was 10.3 per cent. In 3.9 per cent superficial infections occurred, but in no case was there a deep infection involving the bone. Functional return (walking) was achieved in all of the survivors who were able to walk at the time of injury, and there were no nonunions.     

Calculation of coronary blood flow from myocardial clearance of systemically administered 133Xe

Clearance curves for arterial and coronary-venous blood were determined after systemic left-ventricle or pulmonary-artery infections of 133Xe, paired with selective left-coronary-artery injections of 133Xe in 20 dogs with closed chest. Coronary blood flows calculated from systemic and coronary-artery injections were comparable only when a correction was made for arteriol recirculation of 133Xe following the systemic injection (r = 0.962) for left ventricle and 0.932 for pulmonary artery, paired with coronary artery). Experiments in four other dogs, verified that clearance of 133Xe from the pulmonary circulation was only about 60%. The myocardium/blood 133Xe partition coefficient, determined in vivo in ten dogs, agreed within 10% with that previously determined in vitro.