Western Society for Clinical Research 777 purified phytohemagglutinin is heat labile, water soluble, of high molecular weight, giving l)ositi\,c protein and l)~)lysacch~il.icl~, rractions and containing 4.3 per cent N. It is electro- phoretically homogenous over a wide pH range, possessing a slow mobility and an isoelectric point around 5.6. It is therefore concluded that it is a mucopolysaccharide.

It is a powerful agglutinin for erythrocytes and its use in separating leukocytes for culture or chemical studies gives excellent results. The optimum amount for maximum recovery of leukocytes is about 0.1 mg. per ml. of blood. INSULIN TOLERANCE TESTS IN PATIENTS RECEIV-

ING LARGE DOSES OF EXOGENOUS INSULIN. Gmald T. Perkoj and Frank H. ‘Tyler, * Depart- ment of Medicine, University of Utah College of Medicine, Salt Lake City, Utah. In 1938 Fraser et al. reported that the hypo-

glycemia caused by the administration of small intravenous doses of crystalline insulin to pa- tients with islet cell adenomas is not followed by the hyperglycemia which occurs in normal individuals, a phenomenon referred to as hypo- glycemia unresponsiveness. Although such an intravenous insulin tolerance test has been used extensively in the study of certain other dis- orders, e.g., adrenal insufficiency, its validity as a diagnostic tool in islet cell adenoma has been questioned, primarily because of variable results obtained by certain authors who have administered the insulin subcutaneously and because continued excess secretion of insulin has been thought to induce a state of relative insulin resistance.

In an attempt to test the importance of the latter objection we have performed intravenous insulin tolerance tests in patients receiving insulin shock therapy for psychoses. Each patient had received excessive doses of insulin five times weekly for several weeks.

The results of the insulin tolerance tests in these patients came within the limits of normal. The blood sugar fell to hypoglycemic levels at thirty minutes and returned to control levels or above at one hour. Thus it would appear that their insulin sensitivity remained the same in spite of the repeated administration of large doses of insulin. NATURAL HISTORY AND COURSE OF MALIGNANT

HYPERTENSION. Mary F. Schottstaedt and Maurice Sokolow, * Department of Medicine, Uni- versity of California Medical School, San Francisco, Calif.

.,lTNF., 1951

As part of a long range study of the natural history of hypertension, a survc); was macic 01 all casts of malignant hy-pcrtcnsion SKII in t tIci past ten years at the University of California Hospital. Papilledema in the presence of severe hypertension was accepted as the criterion fog diagnosis. One hundred four cases were in- cluded; follow-up information was obtained in all. The average survival after the discover>- of papilledema was thirteen months in patients with good renal function and four months in those with impaired renal function. In ten well documented cases renal impairment developed in an average of 4.4 months. Autopsies per- formed in thirty-one cases revealed the basic renal lesion to be nephrosclerosis in twrlvc, pyelonephritis in twelve and glomeruloncphritis in seven. The impression that nephrosclerosis is the most likely lesion when good renal function is retained in the presence of hypertension and papilledema was amply verified.

The following table summarizes the course of the disease in our group:

No specific treatment. Sympathectomy. .!

88 7 j

3 2 2. 6

Low sodium, rice diets. ~ 8 2 4 Nephrectomy. ./ 1 ( 1 1 ;

Only patients in whom papilledema disap- peared survived more than thirty months. With the exception of one patient with glomeru- lonephritis, none in whom papilledema disap- peared died of renal insufficiency. This is in contrast to the usual course in untreated pa- tients. Disappearance of papilledema implies a decrease in tempo of malignant hypertension and reversal to benign hypertension. Provided vascular damage is not too extensive, an in- creased survival rate may be expected. Earl! and vigorous treatment is essential in malignant hypertension (1) before renal function is im- paired and (2) before irreparable damage to cerebral and cardiac vessels has occurred. CARDIAC RESERVE IN EXPERIMENTAL MYO-

CARDIAL INFARCTION. ilrthur S&er* and Gerard W. Taylor, Department of Medicine and the Surgical Research Laboratory, Stanford Uni-