Abstract: RADIOACTIVE SUBSTANCES are used in diagnostic procedures because they have exactly the same body chemistry as their nonradioactive counterparts ordinarily employed. For example, if radioactive iodine is administered to a patient, it will go through exactly the same chemical and physiological processes within the body as ordinary iodine. The only difference is that the radioactive iodine may be traced with simple instruments that detect radioactivity and, therefore, a patient whose illness involves some misfunction of iodine metabolism can be studied in this way much more accurately and rapidly than would be possible by older methods. In addition, since concentrations of the radioactive substance in the living patient can be detected and studied, information about body chemistry and physiology which was never obtainable before, is easily studied by this method. Iodine is one of the most commonly used diagnostic tracer elements employed in the hospital because it is specific for the study of thyroid disease. Phosphorus is important for study of the skeleton and its diseases, such as osteogenic sarcoma; iron for the study of blood dyscrasias; strontium and calcium for the study of calcium metabolism; zinc for the study of pancreatic function and disfunction-all may be used at different times and the same general rules of procedure apply to all of these. These radioactive tracer substances are used in a manner entirely different from the methods employed in using radium. Radium is always used confined in some kind of a container, such as a smalt platinum needle, tube, or plaque. It treats the patient solely with its energetic radiation, which penetrates through the container and through the surrounding tissue, like x-rays, and the radium itself does not enter in any way into the body's metabolism, or have any chance to circulate in the body or to escape and contaminate the surroundings.

Abstract: CATARACT is an opacity of the lens of the eye, which causes reduction of vision in varying degrees. It is not a film or growth as is popularly supposed. For purposes of study we can divide cataract into the following types: 1. Senile: occurring in middle and later life. 2. Due to disease or toxic substances, e.g., diabetes, dinitrophenol poisoning, et cetera. 3. Traumatic: occurring as the result of an injury such as a blow to the eye. 4. Congenital: occurring in utero and present at birth. We are most concerned with the first type. Cataractous changes are often noted in the late fifties and increasingly so during the next two decades. They may be sufficient to cut down vision to the point where vision is uncomfortable or they may be so slight that the patient is unaware of any change. The first symptom is a lessening of vision. If the opacity is in the cortex of the lens, the patient will be most comfortable in bright light where the pupil is well contracted. If the opacity is in the nucleus, the patient will see best in dim light where the pupil dilates slightly, allowing better vision through the periphery of the lens. We do not know why senile cataract occurs. It appears to be a part of the general aging process in which tissues lose some of their elasticity and undergo the usual changes of age. The speed with which these changes come to the lens is quite unpredictable, and we have no way at present of arresting the process. Various theories have been offered as to the cause of cataract. Some think that diet plays a part, others feel that a change in the blood sugar level is a cause in all cases (even when diabetes is not present), still others look to a hormonal dysfunction. At present, we

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Abstract: APPRECIATION of the value of oxygen as a therapeutic agent has been rapidly increasing during recent years. In providing oxygen service, efficiency is increased by the centralization of supplies and authority.' One individual should be responsible for the general supervision of oxygen service, and a trained and conscientious assisting personnel must be available at all times to provide and maintain the service. These individuals must keep apparatus clean and in good working order and available for immediate use. They also must keep an adequate supply of gases on hand.