Sameh Ali | Tanta University (original) (raw)

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Papers by Sameh Ali

Research paper thumbnail of Hyperoxia-Induced Oxidative Stress

Prolonged hyperoxia exposure generates excessive reactive oxygen species (ROS) and potentially le... more Prolonged hyperoxia exposure generates excessive reactive oxygen species (ROS) and potentially leads to oxi-dative injury in every organ. We have previously generated Drosophila melanogaster flies that tolerate extreme oxidative stress (90%–95 % O2), a lethal condition to naive flies, through a long-term laboratory selection. We found that hyperoxia-selected (SO2A) flies had a significantly longer lifespan in hyperoxia and paraquat-induced oxidative stress. Prolonged hyperoxia exposure induced a significant ROS accumulation and an increased ex-pression of oxidative stress markers, including lipid peroxidation and protein carbonyl contents in control flies, but not in SO2A flies. Enzymatic assays revealed that antioxidant enzyme activity in SO2A flies was similar to that in control flies. However, in isolated mitochondria and using electron paramagnetic resonance, we observed that SO2A flies displayed a decreased superoxide yield during state 3 respiration as compared to control flie...

Research paper thumbnail of Hypoxia-Adaptation Involves Mitochondrial Metabolic Depression and Decreased ROS Leakage

PLOS One, 2012

Through long-term laboratory selection, we have generated a Drosophila melanogaster population th... more Through long-term laboratory selection, we have generated a Drosophila melanogaster population that tolerates severe, normally lethal, level of hypoxia. This strain lives perpetually under severe hypoxic conditions (4% O 2 ). In order to shed light on the mechanisms involved in this adaptation, we studied the respiratory function of isolated mitochondria from the thorax of hypoxia-adapted flies (AF) using polarographic oxygen consumption while monitoring superoxide generation by electron paramagnetic resonance (EPR) techniques. AF mitochondria exhibited a significant 30% decrease in respiratory rate during state 3, while enhancing the resting respiratory rate during State 4-oligo by 220%. The activity of individual electron transport complexes I, II and III were 107%, 65%, and 120% in AF mitochondria as compared to those isolated from control flies. The sharp decrease in complex II activity and modest increase in complexes I and III resulted in .60% reduction in superoxide leakage from AF mitochondria during both NAD + -linked state 3 and State 4-oligo respirations. These results provide evidence that flies with mitochondria exhibiting decreased succinate dehydrogenase activity and reduced superoxide leakage give flies an advantage for survival in long-term hypoxia.

Research paper thumbnail of Elevated circulating plasma adiponectin in normal weight male patients with stable chronic obstructive pulmonary disease COPD

were performed in all patients and control subjects. We found that plasma adiponectin levels in p... more were performed in all patients and control subjects. We found that plasma adiponectin levels in patients with stable COPD were significantly higher than that in control subjects (18.6 ± 2.4 μg/mL vs. 4.2 ± 0.8 μg/mL, P<0.01). There was no correlation between adiponectin and FEV 1 , FEV 1 /FVC in COPD patients. Our data indicate that COPD patients exhibited higher plasma APN levels compared with healthy control subjects, suggesting a peculiar role for this protein in COPD pathogenesis.

Research paper thumbnail of Hyperoxia-Induced Oxidative Stress

Prolonged hyperoxia exposure generates excessive reactive oxygen species (ROS) and potentially le... more Prolonged hyperoxia exposure generates excessive reactive oxygen species (ROS) and potentially leads to oxi-dative injury in every organ. We have previously generated Drosophila melanogaster flies that tolerate extreme oxidative stress (90%–95 % O2), a lethal condition to naive flies, through a long-term laboratory selection. We found that hyperoxia-selected (SO2A) flies had a significantly longer lifespan in hyperoxia and paraquat-induced oxidative stress. Prolonged hyperoxia exposure induced a significant ROS accumulation and an increased ex-pression of oxidative stress markers, including lipid peroxidation and protein carbonyl contents in control flies, but not in SO2A flies. Enzymatic assays revealed that antioxidant enzyme activity in SO2A flies was similar to that in control flies. However, in isolated mitochondria and using electron paramagnetic resonance, we observed that SO2A flies displayed a decreased superoxide yield during state 3 respiration as compared to control flie...

Research paper thumbnail of Hypoxia-Adaptation Involves Mitochondrial Metabolic Depression and Decreased ROS Leakage

PLOS One, 2012

Through long-term laboratory selection, we have generated a Drosophila melanogaster population th... more Through long-term laboratory selection, we have generated a Drosophila melanogaster population that tolerates severe, normally lethal, level of hypoxia. This strain lives perpetually under severe hypoxic conditions (4% O 2 ). In order to shed light on the mechanisms involved in this adaptation, we studied the respiratory function of isolated mitochondria from the thorax of hypoxia-adapted flies (AF) using polarographic oxygen consumption while monitoring superoxide generation by electron paramagnetic resonance (EPR) techniques. AF mitochondria exhibited a significant 30% decrease in respiratory rate during state 3, while enhancing the resting respiratory rate during State 4-oligo by 220%. The activity of individual electron transport complexes I, II and III were 107%, 65%, and 120% in AF mitochondria as compared to those isolated from control flies. The sharp decrease in complex II activity and modest increase in complexes I and III resulted in .60% reduction in superoxide leakage from AF mitochondria during both NAD + -linked state 3 and State 4-oligo respirations. These results provide evidence that flies with mitochondria exhibiting decreased succinate dehydrogenase activity and reduced superoxide leakage give flies an advantage for survival in long-term hypoxia.

Research paper thumbnail of Elevated circulating plasma adiponectin in normal weight male patients with stable chronic obstructive pulmonary disease COPD

were performed in all patients and control subjects. We found that plasma adiponectin levels in p... more were performed in all patients and control subjects. We found that plasma adiponectin levels in patients with stable COPD were significantly higher than that in control subjects (18.6 ± 2.4 μg/mL vs. 4.2 ± 0.8 μg/mL, P<0.01). There was no correlation between adiponectin and FEV 1 , FEV 1 /FVC in COPD patients. Our data indicate that COPD patients exhibited higher plasma APN levels compared with healthy control subjects, suggesting a peculiar role for this protein in COPD pathogenesis.

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