China
Africa
Explore chapters and articles related to this topic
The Role of Inducible Nitric Oxide Synthase (iNOS) in Myocardial Disease: A Functional Duality
Published in Malcolm J. Lewis, Ajay M. Shah, Endothelial Modulation of Cardiac Function, 2020
The induction of iNOS in this situation may be protective in the down regulation of contractile function in the peri-infarct zone, and the induction of protective proteins such as HSP70, via mechanisms out lined earlier. In fact, experiments in the same rabbit infarct model using the NOS blocker L-nitro arginine or D-arginine to reduce NO production all led to a significant increase in infarct size (Williams et al., 1995). However, long term damage to the myocardium may still result from an excessive NO production in combination with the presence of local free radicals. This would suggest that one of the mechanisms of sustaining the viability of the peri-infarct zone is the maintained production of NO, for example, through the administration of L-arginine, while providing a reducing environment by the concomitant use of potent antioxidants.
Pathology of the Liver: Functional and Structural Alterations of Hepatocyte Organelles Induced by Cell Injury
Published in Robert G. Meeks, Steadman D. Harrison, Richard J. Bull, Hepatotoxicology, 2020
Louis Marzella, Benjamin F. Trump
Damage to liver induced by in vivo ischemia (Marzella and Glaumann, 1981) or by perfusion with nitrogen-saturated buffer (Anundi et al., 1987) begins after 30 min of oxygen deprivation. Increases in intracellular calcium by mechanisms to be discussed may contribute to the injury and calmodulin antagonists, and calcium channel blockers appear to confer some degree of protection against anoxia (Farber and Young, 1981). Provision of substrates, such as fructose, that are readily metabolized to lactate protects against the hypoxic injury if intravascular flow is maintained. The presence of an abundant cellular supply of glycogen also offers some protection against injury (Anundi et al., 1987). Free radicals and other toxic oxygen species generated during reperfusion have also been proposed to contribute to the cell damage induced by ischemia. During ischemia, a reducing environment is created. When oxygen is reintroduced at reflow, the nonenzymatic reduction of oxygen to superoxide anion may occur. During ischemia, degradation of adenine nucleotides occurs and products are generated which can be oxidized enzymatically at reflow with the generation of superoxide.
Natural Algal Photobioreactors for Sustainable Wastewater Treatment
Published in Gokare A. Ravishankar, Ranga Rao Ambati, Handbook of Algal Technologies and Phytochemicals, 2019
D. M. Mahapatra, N. V. Joshi, G. S. Murthy, T. V. Ramachandra
These systems function without the involvement of dissolved oxygen in a highly reducing environment. Under a strict methanogenic environment, at a relatively high organic loading, the process yields methane and carbon dioxide (Chanakya et al., 2012). The water residence time for such ponds is 1–1.5 days with a depth of 2–5 m. These anaerobic ponds are highly efficient at relatively warm temperatures (min 15–20°C) and a pH of ~6.2 (Kayombo et al., 2010). However, these ponds have high organic loading rate of 300 g/m2/day (Quiroga, 2011). Such activities have been possible in tropical climate with optimal efficiency and thus are highly variable based on nature and type of climate in the treatment region (USEPA, 2011). The main pri nciple of these types of deep pond systems is rapid sedimentation and consequent organics degradation providing a clarified effluent. This type of deep pond system also ensures relatively high microorganism removal, as microbes are mostly attached to the solids that fall off into the bottom, and the freely suspended microbes are subsequently turned over into algal communities with decrease in the organic nutrients and predation. The anaerobic pond systems have been usually designed at the start of the ponding treatments unit to capture solids and effectively clarify the water for further treatments (Mahapatra and Ramachandra, 2013; Martinez et al., 2014).
Novel therapeutic opportunities for Toxoplasma gondii, Trichomonas vaginalis, and Giardia intestinalis infections
Published in Expert Opinion on Therapeutic Patents, 2023
Francesca Arrighi, Arianna Granese, Paola Chimenti, Paolo Guglielmi
Treatment of T. vaginalis is accomplished by using compounds belonging to the nitroimidazole class (Figure 2). Metronidazole (MTZ) is the first-line treatment with multi-dose administration (500 mg orally twice daily for 7 days) displaying major effectiveness than single oral dose [54]. Other compounds, belonging to the 5-nitroimidazole drug family and employed for trichomoniasis, are tinidazole (TNZ) and secnidazole (SEC) that have been reported to possess about a 95% success rate in curing T. vaginalis [55]. Compounds belonging this class of agents are pro-drugs, i.e. they are activated in the heavily reducing environment in the interior of trophozoites. However, drug resistance to 5-nitroimidazoles and in particular to MTZ in T. vaginalis was documented since 1962 [56]. Moreover, trichomoniasis treatment is often challenged by drug’s side effects including nausea, vomiting, constipation, cramping, and metallic taste along with other side effects like fatigue, headache, peripheral neuropathy, and leukopenia [57].
An overview on cyanobacterial blooms and toxins production: their occurrence and influencing factors
Published in Toxin Reviews, 2022
Isaac Yaw Massey, Muwaffak Al osman, Fei Yang
It is well established that nitrogen fixation is an important feature of some cyanobacteria species and in terms of nutrition nitrogen-fixing, cyanobacteria are considered the most self-sufficient among other organisms. They are photoautotrophs that require only light energy, CO2, dinitrogen (N2), water and some minerals (Paerl and Huisman 2009, Paerl and Otten 2013, Paerl et al.2016, 2001). Heterocysts are specialized nitrogen-fixing cells. Heterocysts have thick cell wall, do not pose photosynthetic membrane and are larger, clearer and highly refractive under light microscope appearance. They may occur within the filament of photosynthetic cells or terminally on a filament (Paerl and Huisman 2009, Paerl and Otten 2013, Paerl et al.2016, 2001). Due to the differences in size, shape and location of heterocysts, they form a significant component in species identification. Within the heterocysts, the enzyme nitrogenase reduces molecular nitrogen to ammonia, which is incorporated into the amido group of glutamine. The thickened cell wall enables molecular oxygen to enter the cell, to be reduced (Bryant 1994, Paerl et al.2016, 2001), thus helping to maintain a highly reducing environment within the cell, necessary for nitrogen reduction.
Oxidative degradation perturbs physico-chemical properties of hemoglobin in cigarette smokers: a threat to different biomolecules
Published in Inhalation Toxicology, 2021
Payel Biswas, Paromita Seal, Jyotirmoy Sikdar, Rajen Haldar
Beyond that, under normal physiological conditions, approximately 3% of Hb (Faivre et al. 1998) undergoes autoxidation to produce ferric Hb (Fe3+) and very less amount undergoes to further oxidation state, i.e. ferryl state (Fe4+). Roy et al. (2015) has already established that there is higher rate of ferric Hb formation in cigarette smokers. However, nothing is reported regarding the ferryl state of Hb in smokers. Thus, here, we estimated the ferryl Hb in presence of H2O2 and found that the rate of ferryl Hb formation was higher among smokers (Figure 3). Furthermore, ferryl Hb is also associated with a specific form of hemoglobin, where in the presence of H2O2, it can act like peroxidase. The peroxidase-like activity of Hb is characterized by the oxidation of electron donor by ferryl form and this activity is regulated by the reducing environment and the lack of oxidizing equivalents. The peroxidase like activity was significantly higher in smokers’ Hb, as evidenced by spectrophotometric analysis (Figure 4) as well as by polyacrylamide gel electrophoresis (Figure 5). So, this observation further supports the fact of increased ferryl Hb formation in smokers.