Benedict Cassen

Velocity Discontinuity Instability of a Liquid Jet

The instability of a high‐speed liquid jet with a velocity which has a transient rise followed by a linear decay with time is studied experimentally and theoretically. The jet is produced experimentally by subjecting a liquid reservoir to a shock‐wave pressure. Using a shadowgraph technique, in an interval of thirty microseconds four successive quarter‐microsecond exposures were taken using jets of water and ethanol in external atmospheres of air and helium. It is found theoretically that a velocity discontinuity is advanced through the jet at a velocity which is the mean of the instantaneous particle velocities immediately in front of and behind the discontinuity. The discontinuity consists of a thin disk of liquid normal to the jet axis. Nodules previously observed on high‐speed liquid jets [J. Appl. Phys. 25, 569 (1954)] can be explained by this mechanism.

Thyroid gland weight determination from thyroid scintigrams with postmortem verification.

The determination of the weight of the human thyroid gland has become extremely important since the introduction of I131 in the treatment of hyperthyroidism. In most clinics estimates of the weight of the gland are obtained by palpation, which at best is a crude procedure. Allen and Goodwin (1) have recently described a more accurate method. The point-by-point technic of plotting the frontal area occupied by the thyroid gland used by Allen, Libby, and Cassen (2) has been simplified by the introduction of the “scintiscanner” (3, 4) for obtaining an actual size scintigram of the gland. The formula presented by Allen and Goodwin can be readily applied to measurements obtained from a scintigram. In the Wads-worth General Hospital (Los Angeles) this procedure has become routine in the determination of dosages of I131 for the treatment of hyperthyroidism and intractable heart disease (5). As the constant in the formula of Allen and Goodwin was obtained from a very limited series of autopsy and surgical material...

BODY POTASSIUM CONTENT IN PATIENTS WITH MUSCULAR DYSTROPHY

The significance of potassium metabolism in muscle disease has been the subject of investigation and speculation for many years. The essential nature of potassium in the synthesis of muscle protein is well established.’ Potassium has also been implicated in the physiochemical interactions associated with muscle contractions2 It becomes therefore of paramount importance to determine the role of potassium in primary disease of the muscular system. Serum potassium levels in primary muscle disease are consistently within the normal range. Since 95 per cent of the body potassium is intracellular, it is readily apparent that serum values cannot reflect intracellular derangements of potassium metabolism. A more direct approach, which does not depend upon serum potassium levels, has been the measurement of total body exchangeable potassium by means of isotope dilution with radioactive potassium-42.3~~ More recently the whole body radiation counter has succeeded the isotope dilution method in the measurement of body potassium levels. Since the latter instrument has eliminated the necessity for the administration of radioactive potassium tracers, the measurement of body potassium levels in normal family members of patients with muscle disease is p~ssible .~ Previous studies in patients with primary muscle disease have revealed a diminution in total body potassium, which correlated in large measure with the severity of muscle inv~lvement.”~ A similar depression in body potassium was also observed in some normal relatives of these patients. The present investigation is a continuation and extension of these earlier studies. In addition to the measurement of body potassium levels the interrelationship of body potassium and body water in patients with primary muscle disease has also been investigated. The latter investigation stems from reports which have appeared in recent years, indicating a consistent relationship between body potassium and a fundamental component of body composition variously described as “active tissue mass” ( Rubner ) , “lean body mass” ( Behnke) , and ‘‘M3,’’ the residual mass of the body after removal of body mineral, fat, and water from the gross body mass (Allen).e-lo Since this quantity is largely potassium rich muscle, its measurement or further description is of primary interest in understanding muscle disease. I t has been demonstrated, furthermore, that total body

The Diagnosis of Morphologic Abnormalities of the Human Thyroid Gland by Means of I131

In previous reports (1, 2) a method of studying some of the morphological characteristics of the frontal profile of the human thyroid gland in its normal and abnormal states has been presented. The method uses I131 and the directional scintillation counter (3). The outline of the thyroid gland obtained by this method has been called a “scintigram.” It is the purpose of this paper to present the indications for this procedure and to demonstrate some illustrative cases. Method Briefly, the procedure of handling the patient is as follows: If visual outlining of the thyroid gland is recommended by the Hospital Radioisotope Committee, a dose of carrier-free I131, ranging between 100 and 300 microcuries, is administered orally in capsule form (4). The exact dose used within this range depends upon the avidity of the thyroid gland for the isotope. It has been found desirable to have 60 to 80 microcuries of I131 concentrated in the thyroid. The actual outlining procedure is done twenty-four or forty-eight hours a...