Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2006. / Allen M. Orville, Committee Member ; Sheldon W. May, Committee Member ; Jung H. Choi, Committee Member ; Mostafa A. El-Sayed, Committee Member ; Donald F. Doyle, Committee Chair.

No description available.

No description available.

The currently used BOD test attempts to predict oxygen level depletion in a given environment, e.g. a moving stream, and is also a parameter for the design and operation of biological processes. It is run under conditions similar to those occurring in nature, but it has been reported that the oxidation rate in a stream is higher than the corresponding rate obtained from the laboratory BOD test. This study was undertaken to observe the effect of turbulence, light and turbidity, separately and in combinations, on the standard BOD test, using raw sewage samples. Mixing was found to increase the BOD, by an average of 15$. reduce the lag period and increase the ultimate BOD value. Light did not show any appreciable change on the standard BOD test, since only an average 4% increase in BOD^ was found. However, turbidity demonstrated an average reduction of 25% on BOD,, values. When the above physical changes were observed in combinations, the results were not additive. As an example, light and turbidity, in combination, did not reduce the BOD,-decrease to 21% (25%-k%). Instead, the decrease in BOD^ value was 5%. This clearly points out that physical changes to the BOD test should not only be studied separately, but also in combinations. Therefore, this study appears to expose the inade quacy of the present BOD test for actual stream conditions. It has also shown that without further research, extrapolating from the existing standard BOD test,yields questionable results. Inclusion in the BOD test, of the physical characteristics of the stream, is a possible solution to obtaining reliable results. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

The purposes of this study were 1) to investigate the release of cardiac biomarkers resulting from acute bouts of maximal intermittent exercise in a laboratory-based setting and set up an exercise-induced cardiac biomarker release (EICBR) model; 2) to compare the changes in cardiac biomarkers in normoxic and hypoxic environments and determine the effects of hypoxia; 3) to investigate the changes in oxidative stress biomarkers resulting from acute bouts of maximal intermittent exercise in normoxic and hypoxic environments at multiple time points; and 4) to observe the relationship between oxidative stress and EICBR and explore the hypothesis that lipid peroxidation triggers the release of cardiac biomarkers from the cytosolic pool. The maximal oxygen consumption (VO2max) and the corresponding velocity of VO2max (vVO2max) of ten well-trained male marathon runners (age 22.1±2.6 y, body mass 64.0±4.9 kg and height 177.3±3.9 cm) was determined under normoxic (FIO2=21.0%, VO2max_N=64.72±5.63 ml∙kg-1∙min-1 and vVO2max_N=18.2±1.0 km∙h-1) and hypoxic (FIO2=14.4%, VO2max_H=62.16±6.74 ml∙kg-1∙min-1 and vVO2max_H=16.7±0.7 km∙h-1) conditions in two experimental trials. One set of conditions was tested in each trial. The order in which each participant faced each trial was selected at random and the trials were separated by 72 h. The ten participants also completed three maximal intermittent exercise protocols, under normoxic (trial N, FIO2=21.0%), absolutely hypoxic (trial AH, FIO2=14.4%) and relatively hypoxic (trial RH, FIO2=14.4%) conditions. The order in which the participants faced the three conditions was once again selected at random and the protocols were separated by at least 7 d. Each bout of maximal intermittent exercise in trials N and AH consisted of a hard run of 16.4±0.9 km∙h-1 (90% vVO2max_N) for 2 min, followed by an easy run of 9.1±0.5 km∙h-1 (50% vVO2max_N) for 2 min with a 2% slope. In trial RH, each bout of exercise consisted of a hard run of 15.0±0.6 km∙h-1 (90% vVO2max_H) for 2 min, followed by an easy run of 8.4±0.3 km∙h-1 (50% vVO2max_H) for 2 min with a 2% slope. Each of the three trials consisted of 23 bouts of maximal intermittent exercise, performed over 92 min. Measurements of the serum of the antecubital venous blood were performed pre- and post- (0 h, 2 h, 4 h and 24 h) exercise. The measurements were taken at five time points for each of the three conditions. The cardiac damage biomarkers of high sensitivity cardiac troponin T (hs-cTnT) and cardiac troponin I (cTnI) and the oxidative stress biomarkers of malondialdehyde (MDA), lipid hydroperoxide (LH), superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) and total antioxidant capacity (TAOC) were analysed. Heart rate (HR) and arterial oxygen saturation (SaO2) were recorded before and during exercise. Due to the skewed distribution of the data (P<0.05), a non-parametric Friedman’s test was used to compare the differences in the levels of hs-cTnT and cTnI between pre- and post-exercise and at each time point for the three conditions. MDA, LH, SOD, CAT, GSH, TAOC and HR were normally distributed (P>0.05) and were analysed using one-way repeated ANOVA tests. Pearson’s product moment correlation coefficients were used to determine the degree of association between the peak levels of hs-cTnT and cTnI, and MDA, LH, SOD, CAT, GSH and TAOC. In trial N, the level of hs-cTnT was elevated 0 h post-exercise (9.628±3.797 pg∙ml-1 was significantly different from the pre-exercise level of 5.118±1.857 pg∙ml-1, P=0.005), reached its peak level 2 h post-exercise (24.290±18.628 pg∙ml-1 was significantly different from the pre-exercise level, P=0.005) and returned to the baseline level at 24 h post-exercise (5.978±1.849 pg∙ml-1). The peak levels of hs-cTnT (N, AH 37.001±31.995 pg∙ml-1, RH 28.614±23.628 pg∙ml-1) and cTnI (N 0.0375±0.0437 ng∙ml-1, AH 0.0475±0.0533 ng∙ml-1, RH 0.0345±0.0375 ng∙ml-1) did not significantly differ under the three conditions. In trial AH, the peak levels of hs-cTnT (2 h, 4 h) and cTnI (2 h, 4 h) were highly related to the MDA_0h and the TAOC_24h. In trial RH, the peak levels of hs-cTnT (2 h, 4 h) and cTnI (2 h, 4 h) were highly related to the TAOC_4h. It was concluded that maximal intermittent exercise can be used to trigger EICBR. The stimulus of hypoxia did not induce more cardiac damage in this exercise model. Maximal intermittent exercise potentially triggers EICBR through oxidative stress, especially lipid peroxidation. Keywords: cardiac biomarkers, hs-cTnT, cTnI, oxidative stress, hypoxia

Isobutylamine N-hydroxylase (IBAH) and flavin reductase (FRED) from Streptomyces viridifaciens are part of a two-component flavin-dependent monooxygenase enzyme system that catalyze the conversion of isobutylamine (IBA) to isobutylhydroxylamine (IBHA), a key step in the formation of valanimycin, an azoxy antibiotic. In this work, we present the over-expression, purification and biochemical characterization of this two-component enzyme system. IBAH and FRED were expressed and purified to homogeneity as separate proteins. FRED exhibited the oxidoreductase activity by catalyzing the oxidation of NADPH. The hydroxylation activity of IBAH was confirmed using liquid chromatography – mass spectrometry (LC-MS). Steady state kinetic data showed an oxidation activity of the monooxygenase component which proceeded at 1.97 ± 0.06 s⁻¹ as measured from oxygen consumption and in product formation, the rate was 0.012 ± 0.001 s⁻¹ , suggesting a high degree of uncoupling between product formation and oxygen consumption. In pre-steady state kinetic characterization studies, the FRED-catalyzed reduction of FAD by NADPH occurred at a rate of 10.0 ± 0.2 s⁻¹ and the KM was 490 ± 40 µM. The rate of reduction was ~1.5-fold decreased in the presence of substrate IBA whiles the KM was 500 ± 50 µM. NADH showed a markedly reduced rate of reduction with a kred of 0.34 ± 0.03 s⁻¹ with an apparent KM of 3000 ± 500 µM. The rate of flavin re-oxidation in the absence of monooxygenase IBAH was 4.79 × 10⁻⁹ M-1 s⁻¹. Our results suggest a reaction mechanism for the IBAH monooxygenase system controlled by the oxidation half reaction that may be modulated by a complex formation between the reductase and monooxygenase components. / Master of Science in Life Sciences

Cartilage tissue specimens were obtained from the flexor surface of the navicular bone and distal radiocarpal bone articular surface (controls) from 8 horses 2 to 5 years old. Water, DNA, total collagen, total glycosaminoglycans, chondroitin sulphate, and keratan sulphate contents were determined. The results from each site were compared and the differences were analyzed by paired t-test (P < 0.05). Significant differences were determined between the water content of the navicular bone flexor surface cartilage (68.32&#177; 3.46 % ) and the distal radiocarpal bone articular surface cartilage (60.60&#177; 4.09%). The total DNA content, total glycosaminoglycan content, total chondroitin sulphate content, and total keratan sulphate for the flexor surface of the navicular bone was: 524.51&#177; 92.89 ng, 0.1533&#177; 0.0338 mg, 0.1018&#177; 0.0197 mg 0.0800&#177; 0.0176 mg, and 0.0092&#177; 0.0037 mg per mg of dry weight cartilage, respectively. The total DNA content, total glycosaminoglycan content, total chondroitin sulphate content, and total keratan sulphate for the distal radiocarpal articular surface cartilage was: 508.80&#177; 70.16 ng, 0.1686&#177; 0.00838 mg, 0.0919&#177; 0.0191, 0.0615&#177; 0.0109 mg, and 0.0074&#177; 0.0029 mg per mg dry weight cartilage, respectively. Not significant differences were determined between these values. We concluded that the cartilage of the flexor surface of the navicular bone is biochemically similar to hyaline articular cartilage, but differs from previous descriptions of fibrocartilage. Further studies are needed to determine types and proportions of collagen types of the flexor surface of the normal navicular bone. These findings establish a basis of comparison to assess navicular cartilage in aging, disease, and repair. / Master of Science

LD2668 .T4 1966 S971 / Master of Science

No description available.

published_or_final_version / abstract / Microbiology / Master / Master of Philosophy