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Muscle and Nerve Histology
Published in Maher Kurdi, Neuromuscular Pathology Made Easy, 2021
Each mitochondrion structurally consists of outer and inner membranes. The inner membrane is rich in cardiolipin and folded to form cristae, which makes it highly impermeable to ions, electrons, and proteins. Unlike the outer membrane, the inner membrane does not contain porins. Both membranes share “contact sites” to exchange proteins and molecules. Additionally, a large number of protein complexes called respiratory chains are present in the inner membrane surface. Each respiratory chain is composed of the following enzymes: Complex I: Nicotinamide adenine dinucleotide (NADH)Complex II: Succinate dehydrogenase (SDH)Complex III: Cytochrome C reductase (CCR)Complex IV: Cytochrome C oxidaseComplex V: ATP synthase
Mitochondrial Dysfunction in Huntington Disease
Published in Abhai Kumar, Debasis Bagchi, Antioxidants and Functional Foods for Neurodegenerative Disorders, 2021
Md. Hafiz Uddin, Marufa Rumman, Tasnuva Sarowar
Mitochondrial respiratory chain complexes consist of NADH-ubiquinone oxidoreductase (complex I), succinate ubiquinone oxidoreductase (complex II), ubiquinone-cytochrome c reductase (complex III), cytochrome c oxidase (complex IV), and ATP synthase (complex V). In addition, there are two electron carriers—ubiquinone (coenzyme Q) and cytochrome c—located in the inner mitochondrial membrane and intermembrane space respectively (Schon and Manfredi 2003). Altered ETS in HD pathology indicates the role of mitochondria in neurodegeneration (Sack 2010). In the development of HD, a decrease in the activity of the mitochondrial complexes I, II, III, and IV has been reported. The mutant huntingtin (mHTT) compromises complex II activity as well as ATP production and the Ca2+ buffering capacity (Parker et al. 1990; Gu et al. 1996; Browne et al. 1997).
Relation Between Contraction and Metabolic Efficiency
Published in Samuel Sideman, Rafael Beyar, Analysis and Simulation of the Cardiac System — Ischemia, 2020
Joseph Kedem, M. Scheinowitz, E. Furman, J. Sonn, H. R. Weiss
The results of this study seem to indicate that Myocardial oxygen supply to demand ratio may be reversibly variable. Therefore, efficiency of contraction is not constant.Intracellular PO2 is not a direct quantitative consequence of the supply to demand ratio.Differences in oxygen cost of contraction may be due to varying efficiencies in the production of ATP. One possible mechanism for this may be different degrees of coupling between the respiratory chain and phosphorylation of ATP.Differences in efficiency may also be due to differences in utilization of ATP. These may include different proportion of ATP used by the contraction process; different contraction dynamics (twisting, heterogeneity); and different proportion of heat production at different physiological and pathological states.
Effects of topical Coenzyme Q10, Xanthan Gum and Sodium Hyaluronate on corneal epithelial wound healing
Published in Clinical and Experimental Optometry, 2022
Leyla Asena, Gülşah Gökgöz, Fatma Helvacıoğlu, Gonca Özgün, Emine Ebru Deniz, Dilek Dursun Altinors
Coenzyme Q10 (CoQ10) is a vitamin-like benzoquinone compound which has been evaluated as a candidate to promote corneal wound healing.19–22 Coenzyme Q10 is an organic molecule composed of a hydrophobic tail and a redox active quinone ring. It is present in biological membranes, particularly in mitochondria where it serves as an electron transporter in complexes I, II and III of the mitochondrial respiratory chain.23 The reduced form of CoQ10 is an effective endogenous cellular antioxidant. It also has antiapoptotic and anti-inflammatory functions.19,21 It can improve the viability of corneal epithelial cells in culture and the administration of CoQ10 after corneal epithelium removal promotes corneal wound healing.22 In a recent case series, it was reported that challenging refractory corneal ulcers showed satisfactory healing response to adjuvant CoQ10 eye drops.24 In another study evaluating the postoperative effects of topical coenzyme Q 10 + vitamin E D-α-tocopherol polyethylene glycol 1000 succinate after cataract surgery, a positive effect was observed in restoring corneal sub-basal nerve plexus anatomy and ocular surface stability.6 In our study, the group receiving topical CoQ10 showed similar macroscopic epithelial healing with other treatment groups, however the electron microscopic examination revealed a better organised epithelial layer more close to a healthy corneal epithelium.
Neuroprotective effects of natural compounds on neurotoxin-induced oxidative stress and cell apoptosis
Published in Nutritional Neuroscience, 2022
Bo Chen, Jingjing Zhao, Rui Zhang, Lingling Zhang, Qian Zhang, Hao Yang, Jing An
Reactive oxygen and nitrogen species are produced by several endogenous and exogenous processes. Free radicals are referred to molecular entities or molecular fragments that contain one or more unpaired electrons and are paramagnetic. Most of the free radicals are short-lived, unstable and highly reactive[11]. ROS represent the most important class of free radicals produced in living systems. ROS are generated during aerobic respiration, cellular metabolism, or in response to pathogens defense. Oxygen molecular (O2) has a unique electronic configuration and is a free radical itself. O2 can easily accept a single electron to form O2•−. O2•− is considered to be the main ROS, which can further interact with other molecules to produce more radical species either directly or through enzyme or metal catalyzed processes[12]. The mitochondrial electron transport chain (ETC, respiratory chain) is one of the primary sources of ATP in mammalian cells. ROS are metabolic byproducts of aerobic respiration occurring in the inner membrane of the mitochondria. During energy transduction, O2 is the final acceptor of electrons and protons, and it is reduced by four electrons to produce two molecules of water (H2O). Some of the redox centers in the ETC may leak electrons to O2, partially reducing this molecule to O2−• and then to H2O2 and HO•[13].
Targeting the gut microbial metabolic pathway with small molecules decreases uremic toxin production
Published in Gut Microbes, 2020
Yingyi Wang, Jianping Li, Chenkai Chen, Jingbo Lu, Jingao Yu, Xuejun Xu, Yin Peng, Sen Zhang, Shu Jiang, Jianming Guo, Jinao Duan
NADH-ubiquinone oxidoreductase (complex I) is the core point for electrons to pass through the E. coli respiratory chain.40,41 Complex I is important for the formation of the proton motive force in the bacterial membrane. ComplexⅠcouples electron transfer from NADH to ubiquinone with the transport of four protons across the inner membrane. Complex I converts NADH to NAD+ and protons, and the electrons liberated from this reaction are shuttled to the respiratory chain. Thus, the NADH/NAD+ ratio is another way to reflect complex I activity. If complex I activity is inhibited, the NADH/NAD+ ratio will increase because less NADH is catalyzed to NAD+. Consistent with results obtained on complex I activity, the NADH/NAD+ ratio increased significantly after E. coli was treated by ISO for 1 h (Figure 3d).