Home About us Contact
|
Home About us Contact | ||
|
|
||
Scavenging System (scavenging + system)
Selected AbstractsDiabetic embryopathy: Studies using a rat embryo culture system and an animal modelCONGENITAL ANOMALIES, Issue 3 2005Shoichi Akazawa ABSTRACT The mechanism of diabetic embryopathy was investigated using in vitro experiments in a rat embryo culture system and in streptozotocin-induced diabetic pregnant rats. The energy metabolism in embryos during early organogenesis was characterized by a high rate of glucose utilization and lactic acid production (anaerobic glycolysis). Embryos uninterruptedly underwent glycolysis. When embryos were cultured with hypoglycemic serum, such embryos showed malformations in association with a significant reduction in glycolysis. In a diabetic environment, hyperglycemia caused an increased glucose flux into embryonic cells without a down-regulation of GLUT1 and an increased metabolic overload on mitochondria, leading to an increased formation of reactive oxygen species (ROS). Activation of the hexamine pathway, subsequently occurring with increased protein carbonylation and increased lipid peroxidation, also contributed to the increased generation of ROS. Hyperglycemia also caused a myo-inositol deficiency with a competitive inhibition of ambient glucose, which might have been associated with a diminished phosphoinositide signal transduction. In the presence of low activity of the mitochondrial oxidative glucose metabolism, the ROS scavenging system in the embryo was not sufficiently developed. Diabetes further weakened the antioxidant system, especially, the enzyme for GSH synthesis, ,-GCS, thereby reducing the GSH concentration. GSH depletion also disturbed prostaglandin biosynthesis. An increased formation of ROS in a diminished GSH-dependent antioxidant system may, therefore, play an important role in the development of embryonic malformations in diabetes. [source] Reactive Oxygen Species Scavenging Enzymes and Down-Adjustment of Metabolism Level in Mitochondria Associated with Desiccation-Tolerance Acquisition of Maize EmbryoJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 7 2009Jing-Hua Wu Abstract It is a well-known fact that a mature seed can survive losing most of its water, yet how seeds acquire desiccation-tolerance is not well understood. Through sampling maize embryos of different developmental stages and comparatively studying the integrity, oxygen consumption rate and activities of antioxidant enzymes in the mitochondria, the main origin site of reactive oxygen species (ROS) production in seed cells, we found that before an embryo achieves desiccation-tolerance, its mitochondria shows a more active metabolism, and might produce more ROS and therefore need a more effective ROS scavenging system. However, embryo dehydration in this developmental stage declined the activities of most main antioxidant enzymes and accumulated thiobarbituric acid-reactive products in mitochondria, and then destroyed the structure and functional integrity of mitochondria. In physiologically-matured embryos (dehydration-tolerant), mitochondria showed lower metabolism levels, and no decline in ROS scavenging enzyme activities and less accumulation of thiobarbituric acid-reactive products after embryo dehydration. These data indicate that seed desiccation-tolerance acquisition might be associated with down-adjustment of the metabolism level in the late development stage, resulting in less ROS production, and ROS scavenging enzymes becoming desiccation-tolerant and then ensuring the structure and functional integrity of mitochondria. [source] NaCl treatment markedly enhances H2O2 -scavenging system in leaves of halophyte Suaeda salsaPHYSIOLOGIA PLANTARUM, Issue 4 2005Pang Cai-Hong The C3 halophyte Suaeda salsa L. grown under the high concentration of NaCl (200 mM) was used to investigate the role of the hydrogen peroxide (H2O2)-scavenging system [catalase, ascorbate peroxidase, glutathione reductase (GR), ascorbic acid, and glutathione (GSH)] in removal of reactive oxygen species. The activity of catalase (CAT, EC 1.11.1.6), ascorbate peroxidase (APX, EC 1.11.1.11), and GR (EC 1.6.4.2) increased significantly after 7 days of NaCl treatment. The isoform patterns of CAT and GR were not affected, but the staining intensities were significantly increased by NaCl treatment. Activities of both the thylakoid-bound APX or GR and stromal APX (S-APX) or GR in the chloroplasts were markedly enhanced under high salinity. Fifty percent of APX in the chloroplasts is thylakoid-bound APX. S-APX and GR activity represented about 74,78 and 64,71% of the total soluble leaf APX and GR activity, respectively. Salt treatment increased the contents of ascorbic acid and GSH. By contrast, a decreased content of H2O2 was found in the leaves of NaCl-treated S. salsa. The level of membrane lipid peroxidation decreased slightly after NaCl treatment. The plants grew well with high rate of net photosynthesis under high salinity. These data suggest that upregulation of the H2O2 -scavenging system in plant cells, especially in the chloroplasts, is at least one component of the tolerance adaptations of halophytes to high salinity. [source] A nonoccluding bag and closed scavenging system for the Jackson Rees modified T-piece breathing systemANAESTHESIA, Issue 5 2000S. S. Dhara We used the inner tube and its 22-mm connector from the patient end of a Bain breathing system to splint the double-ended bag of the Jackson Rees modification of the Ayre's T-piece breathing system. A paediatric airway pressure-limiting valve was connected to the distal end of the tube for closed scavenging. The resistance of the modified bags was similar to that of unmodified bags at gas flows below 11 l.min,1. The valve offered no resistance to gas flows below 5 l.min,1. During its use in 30 paediatric patients, analysis of carbon dioxide from inside the bag and from the expiratory port confirmed no loss of deadspace gas by preferential flow bypassing the bag into the scavenging system. [source] The role of triterpenoid on reactive oxygen scavenging system: Approach from the new chemiluminescence system (XYZ system)BIOFACTORS, Issue 1-4 2000Kazuyoshi Okubo Abstract We propose that the reactive oxygen species/hydrogen donor/mediator system (XYZ system) is a new chemiluminescence system for the measurement of reactive oxygen scavenging activity. By using this method, we demonstrated the role of triterpenoid on a reactive oxygen scavenging system. DDMP (2,3-dihydro-2,5-dihydroxy-6-methyl-4H-pyran-4-one) conjugated saponin from soybean, produced a low level light emission in the presence of H_2O_2 (X) and gallic acid (Y). The soybean saponin acted as a mediator (Z) on the reactive oxygen scavenging system. When comparing the data of photon emission properties of saponin with that of cholic acids, it concludes that DDMP moiety of soybean saponin plays an important role rather than the aglycon moiety in the radical scavenging system. [source] Roles of reactive oxygen species in the corpus luteumANIMAL SCIENCE JOURNAL, Issue 6 2006Norihiro SUGINO ABSTRACT Cells living under aerobic conditions always face the oxygen paradox. Oxygen is necessary for cells to maintain their lives. However, reactive oxygen species such as superoxide radicals, hydroxyl radicals and hydrogen peroxide are generated from oxygen and damage cells. Oxidative stress occurs as a consequence of the excessive production of reactive oxygen species and impaired antioxidant defense systems. Antioxidant enzymes include superoxide dismutase (SOD), which is a specific enzyme to scavenge superoxide radicals; copper-zinc SOD, located in the cytosol and Mn-SOD, located in the mitochondria. Both types of SOD belong to the first enzymatic step to scavenge superoxide radicals. It has been reported that a number of local factors such as cytokines, growth factors and eicosanoids are involved in the regulation of the corpus luteum (CL) function in addition to gonadotropins. Since reactive oxygen species are generated and SOD is expressed in the CL, there is a possibility that reactive oxygen species and SOD work as local regulators of the CL function. The present review reports that reactive oxygen species and their scavenging systems play important roles in the regulation of the CL function. [source] | ||||||||||