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• The partially purified transketolase from each of eight well-nourished patients with Alzheimer's disease contained significantly less heat-stable component with a significantly longer half-life of heat inactivation than that from eight controls. Immunochemical studies utilizing antibodies to the purified human liver transketolase did not distinguish between red blood cell transketolases of patients with Alzheimer's disease and those of controls. However, three brains from patients with Alzheimer's disease that were deficient in transketolase activity lacked a 69-kilodalton form on immunoblots. Subtle structural abnormalities of transketolase appear to occur in a high proportion of patients with Alzheimer's disease.

THE INCREASING use of total fasting as an effective method of producing weight loss in the very obese has led to a review of the status of vitamin nutrition in such individuals. Although it has been suggested by some authors1,2that vitamin deficiency does not occur during a total fast and others3,4have recommended the routine use of vitamin supplements, no supporting data have been offered. Such data as are available were obtained during semistarvation regimens,5-7were usually secured during observations of normal nonobese humans and were based upon urinary vitamin excretion. Since, in current use, fasting as a therapeutic procedure ordinarily involves no caloric intake for periods of a week or more in markedly overweight patients, we have undertaken this study of thiamine changes in patients so treated using erythrocyte transketolase activity as an improved technique for functional evaluation of thiamine metabolism. The observations indicate

Beriberi heart disease, a cardiac disorder due to a deficiency of thiamine, is relatively rare, and its diagnosis is commonly missed. The estimation of blood transketolase activity, a simple, sensitive, and specific assay which can detect significant thiamine deficiency, has been useful in establishing a diagnosis of beriberi heart disease. An acute form of high-output cardiac decompensation developed in five chronic alcoholic, inadequately nourished patients. In each case, blood transketolase determinations prior to therapy showed clear evidence of moderately severe thiamine deficiency. The enzyme assay is useful as a diagnostic tool in heart disease and a variety of nutritional disorder.

To the Editor:— I have read with considerable interest Dr. Haunz's answer to "MD, Florida" [ 201 :901, 1967] but am rather concerned that large intravenous doses of thiamine hydrochloride, ie, 100 mg daily for seven days, are recommended. Doses of this vitamin given on its own are liable to induce anaphylactoid reactions, and there are at least six fatal cases published in the world literature. However, from experience in the United Kingdom, when such large doses of thiamine hydrochloride are given intravenously with other members of the B complex (eg, in the treatment of certain psychiatric emergencies) the risk of such reactions is negligible. I would agree with your contributor that prolonged thiamine deficiency could be a possible reason for apparent carbohydrate dyspepsia, but I would like to suggest, with respect, that estimation of erythrocyte transketolase activity inThe Journal( 187 :762, 1967) is a more specific indicator of thiamine