Thesis (doctoral)--Universität München, 1934. / "Lebenslauf": p. [33]. Includes bibliographical references.

Thesis (doctoral)--Universität München, 1934. / "Lebenslauf": p. [33]. Includes bibliographical references.

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 B₆, serves as the coenzyme for these transaminases. Compared to other methods of vitamin B₆ 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 μg 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 μg pyruvate/mg Hb/hr and 11.70 ± 7.00 percent, respectively. Those of EGOT were 23.30 ± 5.77 μg 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 (p < 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 B₆ 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. / Graduation date: 1976

Digitized by Kansas Correctional Industries

Thesis--Chemistry : Chicago : 1919. / Dlr. "Private edition, distributed by the University of Chicago Libraries, Chicago, Illinois." "Reprinted from the Journal of biological chemistry, Vol. XXXVIII, No. 3, July, 1919." Notes Bibliographiques.

Heterocyclic amines and Lipid oxidation products are important classes of toxins in food. Prevention of their formation in food might minimize their dietary exposure and lower their health risk to people. This research work is to identify the potential vitamins which may inhibit the formation of these toxins. Moreover, the possible inhibition mechanism for potent inhibitor(s) is also investigated. The first part was related to heterocyclic amines which are a class of important Maillard reaction products. The inhibitory activities of 11 water-soluble vitamins against heterocyclic amine formation were examined in a PhIP and a MeIQx producing chemical model. Six investigated vitamins (pyridoxiamine, pyridoxine, nicotinic acid, biotin, thiamine and L-ascorbic acid) out of eleven, exhibited significant inhibition (>40%) in both models. The activity of pyridoxamine, niacin, alpha-tocopherol, retinol acid and ascorbic acid was further investigated using fried beef. Moderate inhibition (20%) of the formation of PhIP, 4,8-DiMeIQx and MeIQx was found for most of them; whereas pyridoxamine reduced the levels of all three HAs by 40%. LC–MS analysis revealed that pyridoxamine directly reacts with phenylacetaldehyde to form an adduct which was characterized by LC-MS and NMR spectroscopy. The second part was related to cholesterol oxidation products (COPs). The capacities of 15 vitamins to inhibit the formation of 7α-hydroxycholesterol, 7β-hydroxycholesterol and 7-ketocholesterol was examined in beef patties. Among them, L-ascorbic acid, retinoic acid, and α-(±)-tocopherol were found to exert a potent inhibitory effect (30−50%) on the formation of three COPs. Pyridoxamine inhibited 7-ketocholesterol formation by 60% and it could directly react with 7-ketocholesterol via the addition reaction. Finally, the inhibitory activities of 15 vitamins against Malondialdehyde (MDA) formation were examined in beef patties samples. Solid Phase Extraction (SPE) and TBA test were performed followed by HPLC-DAD analysis. Five vitamins (pyridoxiamine, pyridoxine, retinoic acid, α-tocopherol and L-ascorbic acid) exhibited significant inhibition (>20%) in triplicate experiments. The fatty acid profile was examined by GC-MS and significant difference was only observed for three antioxidants (retinol acid, L-ascorbic acid and alpha-tocopherol) but not pyridoxamine. An alternative explanation for the inhibition mechanism against lipid oxidation was proposed for pyridoxmine. With the application of chromatographic and spectral analysis (LC–MS and NMR), it was demonstrated that pyridoxamine could directly react with Malondialdehyde via addition reaction. In summary, certain vitamins were found to be potential inhibitors against both heterocyclic amines and lipid oxidation products formation. Mechanistic studies showed that direct-trapping of these toxins and the intermediate compounds for their formation by pyridoxamine and other vitamins was an effective way to lower the concentration of these food toxins during high-temperature processing. / published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy

Graduation date: 1950

Graduation date: 1950

Thesis (Ph. D.)--University of Chicago. / "Private edition, distributed by the University of Chicago Libraries, Chicago, Illinois." "Reprinted from the Journal of biological chemistry, Vol. XXXVIII, No. 3, July, 1919." Includes bibliographical references.

Thesis (Ph. D.)--Columbia University, 1923. / Vita. Bibliography: p. 25-27.