AN ABSTRACT OF THE THESIS OF DANG THI CUC PHUONG for the degree of MASTER OF SCIENCE Foods and Nutrition in (Nutrition) presented on June 19, 1975 Title: FACTORS AFFECTING ERYTHROCYTE TRANSAMINASE ACTIVITY IN PRESCHOOL CHILDREN

approved: Lorraine Miller Erythrocyte glutamic-pyruvic transaminase (EGPT) and glutamic-oxaloacetic transaminase (EGOT) activities reflect vitamin B6 status in humans (Baysal, Johnson, and Linkswiler, 1966). Pyridoxal phosphate (PALPO), an active form of vitamin B,, serves as the coenzyme for these transaminases. Compared to other methods of vitamin Bg assessment, transaminase measurement has the advantage of dealing with a single enzyme requiring PALPO and reflecting the subject's vitamin B6 status over a long period of time (Sauberlich et al. , 1970) . Although studies on transaminase activity in adults have been reported, information on EGPT and EGOT activities in children is not available. This study was undertaken to determine the activities of EGPT and EGOT in normal preschool, children. In addition, factors affecting transaminase activities were considered. The storage stability of EGPT and EGOT was also reported. Participating in this study were 109 subjects, aged from 21 to 126 months. The activities of EGPT and EGOT were expressed as yg pyruvate/mg hemoglobin (Hb)/hr and mg pyruvate/ml red blood cells/hr. The basal activity indicates the level of holoenzyme. The stimulated activity with added in-vitro PALPO shows the level of holoenzyme plus apoenzyme. The percent stimulation represents the degree of saturation of apoenzyme with the coenzyme (Cavill and Jacobs, 1967). For EGPT, the basal activity and percent stimulation were 1.20 ± 0.44 yg pyruvate/mg Hb/hr and 11.70 ± 7.00 percent, respectively. Those of EGOT were 23.30 ± 5.77 yg pyruvate/mg Hb/hr and 69.90 ± 23.3 percent. The two different ways of expressing basal activity of EGPT and EGOT were highly correlated with one another. A significant positive correlation was found between the basal activities of EGPT and EGOT (p < 0.01). However, the positive relationship between their corresponding percent stimulation was> not significant. The stimulated and basal activities for both EGPT and EGOT were closely correlated Cp < 0.01), which indicated that the level of holoenzyme is largely dependent on the amount of-apoenzyme available. A significant inverse relationship (p < 0.01) existed between the basal activity and percent stimulation of EGOT, which meant that the high enzyme activity level is usually associated with a high degree of saturation of the apoenzyme with PALPO. The similar inverse relationship for EGPT was not statistically significant. In the subjects whose diet was supplemented with multivitamins containing pyridoxine, the transaminase activities appeared to be higher and the corresponding percent stimulation lower than in those receiving no supplementation. However, the difference was only significant for basal EGPT, using the Student's ;t test (p < 0.01). The subjects with high basal activities or low percent stimulation of EGPT or EGOT also tended to have higher plasma vitamin B^levels. But these relationships were not significant. As the age of the subjects increased, the basal and stimulated activities of both EGPT and EGOT declined, accompanied by the corresponding increase in percent stimulation. The correlations for basal and stimulated activities, as well as percent stimulation of EGOT, but not EGPT, with age were significant (p < 0.05). The differences in transaminase activities due to sex were not significant. But in general, the girls had a lower basal activity and a higher percent stimulation for both EGPT and EGOT than the boys.. The average hemoglobin level of the subjects was 12.95 ± 0.77 g percent. The hemoglobin levels increased significantly with age (p < 0.01). Finally, experiments with two hemolysate samples showed that no loss of EGPT or EGOT activities occurred with freezing and storage within 13 days. Factors Affecting Erythrocyte Transaminase Activity in Preschool Children by Dang Thi Cue Phuong A THESIS submitted to Oregon State University in partial fulfillment of the requirements for the degree of Master of Science June 1976