Gerald J. Friedman

Effect of Addition of KCN to Whole Blood on Indophenol-reducing Power of Plasma

Pijoan, Townsend and Wilson 1 noted a considerable loss of vitamin C in blood serum done by the Farmer and Abt 2 method. Pijoan and Klemperer 3 reported that this loss could be prevented by the immediate addition of M/50 KCN to the blood. In order to determine the difference in the concentration of vitamin C in blood with and without KCN, the following experiments were done. Forty cc. of venous blood were drawn and placed immediately in an Erlenmeyer flask containing 8 drops of a 20% solution of potassium oxalate. The specimen was shaken gently and divided into two equal fractions, to one of which (B) were added 8 drops of 10% KCN resulting in an M/26 solution of KCN. Both fractions (A and B) were then immediately centrifuged and the plasma drawn off. The separated plasma from each fraction was divided into four 2 cc. portions. One of each of these samples (0 and 0) was precipitated immediately, using 2 cc. of plasma, 4 cc. of redistilled water and 6 cc. of a 10% solution of metaphosphoric acid. These samples were then centrifuged for 5 minutes and the filtrate decanted off. Three cc. samples of the filtrate were used for the titrations, which were done by the Farmer and Abt modification of the Tillmans method. 4 The remaining 6 plasma specimens (3 with KCN and 3 without KCN) were placed in the icebox and determinations of the vitamin C content were done after intervals of approximately 30, 90 and 160 minutes as shown in the chart. The first determinations, in this experiment, were done 45 minutes after the blood was drawn. This represents the maximum time required for preparing the filtrate; the average time taken in other experiments was 25 minutes.

An Excretory Test for Vitamin C Deficiency and Subnutrition

Summary 1. The 3-hour urinary excretion of vitamin C before and after an intravenous test dose of 100 mg. of ascorbic acid was studied in a group of 12 normal adults on their usual diet which was adequate in vitamin C, in 3 normal adults on diets low in vitamin C and in 13 cases of scurvy. 2. The 3-hour and 21-hour excretion was studied in the same group after an intravenous test dose of 100 mg. of ascorbic acid. 3. Following the test dose the normal subjects excreted an average of more than 40% of the injected vitamin within 3 hours; the subnutrition cases an average of 11% and the scurvy group an average of 2.6%. 4. These observations support the fact that the 3-hour urinary excretion of vitamin C following an intravenous dose of 100 mg. of ascorbic acid will serve as an index of vitamin C deficiency or subnutrition.

Vitamin C Requirement of Man. Prolonged Study of Daily Excretion and Plasma Concentration of Vitamin C.

The vitamin C requirement was determined on 2 male adults who were hospitalized during the study and fed diets containing constant minimal amounts of vitamin C. The 24-hour urinary excretion of vitamin C was determined daily and the plasma concentration 3 times a week. The determination of vitamin C in both plasma and urine was done by the indophenol titration method 1 in the first case and in the second case both by titration and by the photoelectric colorimeter. 2 , 3 The use of the photoelectric colorimeter reduces the error due to the small amount of non-vitamin C reducing substances present in the urine. On the diet fed, titration gave urine figures which were consistently higher by 10 mg per day. No significant differences were found in the plasma values. The first case, L. R., age 57, height 72.5 in., weight 160 lb., was observed for a total of 110 days. In the first period of 19 days he received 50 mg of ascorbic acid daily; during the second period of 53 days he received 100 mg of ascorbic acid daily; during the third period of 22 days, 200 mg daily and during the fourth period of 16 days 350 mg daily. The ascorbic acid was given in divided doses of 50 mg each at regular intervals throughout the day. In the first period the daily excretion of vitamin C averaged 11 mg, the daily retention averaged 39 mg and the blood plasma concentration varied from 0.76 to 0.97 mg %, the average being 0.85 mg %. In the second period the daily excretion averaged 20 mg, the daily retention 80 mg, and the plasma vitamin C varied from 0.93 mg % to 1.22 mg %, the average being 1.12 mg %.

Recovery of Vitamin G from the Human Bladder.

Summary When amounts of synthetic ascorbic acid varying from 0.5 to 30 mg were instilled into the human bladder, 92 to 107% was present in the urine after periods of 1 to 5 hours. It is, therefore, concluded that no appreciable destruction of ascorbic acid occurs in the human bladder.