Sam L. Clark

Vitamin B12 requirement of adult man

Abstract 1.1. Patients with pernicious anemia in relapse have been studied as examples of vitamin B 12 -depleted subjects. A critical study of the minimal dosage of parenterally administered vitamin B 12 required for initial response and the long-term maintenance of these patients has been made. From these data estimates of the dietary requirement of vitamin B 12 have been derived. 2.2. The data on initial response and on maintenance consistently indicate a daily utilization of vitamin B 12 ranging from 0.5 to 2.0 μg., the more usual range being 0.5 to 1.0 μg. Considering the efficiency of absorption by normal persons of quantities of this order of vitamin B 12 we estimate that the minimal daily dietary needs for this vitamin may be met by approximately 0.6 to 2.8 μg., with a narrower range of 0.6 to 1.2 μg. sufficient for most persons. 3.3. Long-term observations on patients receiving smaller than minimal dosage indicate that the demands of vitamin B 12 for hemopoiesis exceed those for other clinically recognized physiologic functions, and that macrocytosis is the most sensitive indicator of vitamin B 12 deficiency. In appraising vitamin B 12 nutriture careful estimates of erythrocyte size therefore are important.

The electroencephalogram in cerebellar seizures

Abstract 1. 1. The EEG recorded in a series of cats undergoing cerebellar seizures was not specific in type. 2. 2. It was unlike the EEG accompanying clonic seizures elicited by cerebral stimulation. 3. 3. Involvement of a specific limb in the slow march of the seizure was not accompanied by specific alteration of the EEG from either side of the brain. 4. 4. The EEG during a cerebellar seizure was best described as an activation pattern. being made of low amplitude fast waves. 5. 5. When tracings from the cerebellum were recorded no alterations were observed during a seizure, but the type of apparatus used did not allow complete analysis of the waves out of the range of the ordinary frequencies of the EEG.

Oral Folic Acid Tolerance Test in Normal Human Subjects and Patients with Pernicious Anemia.

Summary An oral folic acid tolerance test is described and its limitations discussed. Evidence is presented that the test is useful in assessing the absorption of folic acid. No defect in the gastrointestinal absorption of folic acid in patients with pernicious anemia has been demonstrated.

Further Studies on Renal Toxicity of PGA.

Summary 1. The photolytic oxidation products of PGA could not be implicated in the production in guinea pigs of renal lesions by large parenteral doses of PGA. 2. These lesions were uniformly produced in guinea pigs by the daily administration of 8 mg of PGA (20 mg of PGA/kg) for periods of 6-10 days, and they occurred in occasional animals at a daily dosage of 2 mg (8 mg/kg). 3. Ascorbic acid did not appear to be a factor in the production of the lesions.