Rapid Electron Transfer within the III-IV Supercomplex in Corynebacterium glutamicum

Complex III in C. glutamicum has an unusual di-heme cyt. c1 and it co-purifies with complex IV in a supercomplex. Here, we investigated the kinetics of electron transfer within the supercomplex and in the cyt. aa3 alone (cyt. bc1 was removed genetically). In the reaction of the reduced cyt. aa3 with O2, we identified the same sequence of events as with other A-type oxidases. However, even though this reaction is associated with proton uptake, no pH dependence was observed in the kinetics. For the cyt. bc1-cyt. aa3 supercomplex, we observed that electrons from the c-hemes were transferred to CuA with time constants 0.1-1 ms. The b-hemes were oxidized with a time constant of 6.5 ms, indicating that this electron transfer is rate-limiting for the overall quinol oxidation/O2 reduction activity (~210 e-/s). Furthermore, electron transfer from externally added cyt. c to cyt. aa3 was significantly faster upon removal of cyt. bc1 from the supercomplex, suggesting that one of the c-hemes occupies a position near CuA. In conclusion, isolation of the III-IV-supercomplex allowed us to investigate the kinetics of electron transfer from the b hemes, via the di-heme cyt. c1 and heme a to the heme a3-CuB catalytic site of cyt. aa3

Membrane-tethering of cytochrome c accelerates regulated cell death in yeast

Intrinsic apoptosis as a modality of regulated cell death is intimately linked to permeabilization of the outer mitochondrial membrane and subsequent release of the protein cytochrome c into the cytosol, where it can participate in caspase activation via apoptosome formation. Interestingly, cytochrome c release is an ancient feature of regulated cell death even in unicellular eukaryotes that do not contain an apoptosome. Therefore, it was speculated that cytochrome c release might have an additional, more fundamental role for cell death signalling, because its absence from mitochondria disrupts oxidative phosphorylation. Here, we permanently anchored cytochrome c with a transmembrane segment to the inner mitochondrial membrane of the yeast Saccharomyces cerevisiae, thereby inhibiting its release from mitochondria during regulated cell death. This cytochrome c retains respiratory growth and correct assembly of mitochondrial respiratory chain supercomplexes. However, membrane anchoring leads to a sensitisation to acetic acid-induced cell death and increased oxidative stress, a compensatory elevation of cellular oxygen-consumption in aged cells and a decreased chronological lifespan. We therefore conclude that loss of cytochrome c from mitochondria during regulated cell death and the subsequent disruption of oxidative phosphorylation is not required for efficient execution of cell death in yeast, and that mobility of cytochrome c within the mitochondrial intermembrane space confers a fitness advantage that overcomes a potential role in regulated cell death signalling in the absence of an apoptosome

The role of arginase and rho kinase in cardioprotection from remote ischemic perconditioning in non-diabetic and diabetic rat in vivo.

BackgroundPharmacological inhibition of arginase and remote ischemic perconditioning (RIPerc) are known to protect the heart against ischemia/reperfusion (IR) injury.PurposeThe objective of this study was to investigate whether (1) peroxynitrite-mediated RhoA/Rho associated kinase (ROCK) signaling pathway contributes to arginase upregulation following myocardial IR; (2) the inhibition of this pathway is involved as a cardioprotective mechanism of remote ischemic perconditioning and (3) the influence of diabetes on these mechanisms.MethodsAnesthetized rats were subjected to 30 min left coronary artery ligation followed by 2 h reperfusion and included in two protocols. In protocol 1 rats were randomized to 1) control IR, 2) RIPerc induced by bilateral femoral artery occlusion for 15 min during myocardial ischemia, 3) RIPerc and administration of the nitric oxide synthase inhibitor NG-monomethyl-L-arginine (L-NMMA), 4) administration of the ROCK inhibitor hydroxyfasudil or 5) the peroxynitrite decomposition catalyst FeTPPS. In protocol 2 non-diabetic and type 1 diabetic rats were randomosed to IR or RIPerc as described above.ResultsInfarct size was significantly reduced in rats treated with FeTPPS, hydroxyfasudil and RIPerc compared to controls (PConclusionArginase is activated by peroxynitrite/ROCK signaling cascade in myocardial IR. RIPerc protects against IR injury via a mechanism involving inhibition of this pathway and enhanced eNOS activation. The beneficial effect and associated molecular changes of RIPerc is abolished in type 1 diabetes

Use of Robotics to Improve Upper Extremity Function in Adults with Neurological Conditions

Objectives of Presentation: 1. Describe the impact of robotics on upper extremity function among various neurological populations. 2. Differentiate which patients are appropriate for robotics interventions for upper extremity rehabiliation. 3. Defend the feasibility of robotic interventions for upper extremity rehabilitation of neurological populations. PICO: To what extend does robotic-assisted therapy improve UE function in adults with neurological conditions? Note: Handout with references available at bottom of page. Presentation: 37:3

The effect of RIPerc on eNOS expression and peroxynitrite formation.

<p>(A and C) Effect of remote ischemic perconditioning (RIPerc) on phosphorylated of eNOS at Ser1177 (p-eNOS), total eNOS and nitrotyrosine (3NT) in protocol 1. (B) Effect of RIPerc on NOS expression in non-diabetic and diabetic rats of protocol 2. Values are means ± SEM; n = 5–8. *<i>P</i><0.05 vs. CIR.</p

ROCK activity expressed as a phosphorylation of ezrin following ischemia/reperfusion.

<p>(A) Effect of the peroxynitrite decomposition catalyst FeTPPS, the ROCK inhibitor hydroxyfasudil (H.fasudil), remote ischemic preconditioning (RIPerc) and RIPerc+the NOS inhibitor L-NMMA in protocol 1. (B and C) Effect of RIPerC in non-diabetic and diabetic rats of protocol 2. Values are means ± SEM; n = 5–7. ***<i>P</i><0.001 vs. CIR; ^###<i>P</i><0.001 vs. RIPerc and ^††<i>P</i><0.01 vs. ND-CIR.</p

Myocardial area at risk and infarct size.

<p>Area at risk (A and B) expressed as % of left ventricle and infarct size (C and D) expressed as % of the area at risk following 30 min ischemia and 2 hrs reperfusion in rats included in protocol 1 (A and C) and in non-diabetic and diabetic rats included in protocol 2 (B and D). Values are means ± SEM; n = 6–10. **<i>P</i><0.01, ***<i>P</i><0.001 vs. CIR; ^###<i>P</i><0.001 vs. RIPerc and ^†††<i>P</i><0.001 vs. ND-CIR.</p

Hemodynamic changes in Protocol 2.

<p>Values are mean ± SEM; n = 6–7. Abbreviations: MABP (mm Hg), mean arterial blood pressure; HR (beats/min), heart rate; ND-CIR, non-diabetic control ischemia/reperfusion; ND-RIPerc, non-diabeic remote ischemic perconditioning; DM-CIR: diabetes mellitus control ischemia/reperfusion; DM-RIPerc, diabetes mellitus remote perconditioning.</p><p>*<i>P</i><0.05 vs. ND-CIR.</p

Nitrosative modifications of the Ca2+ release complex and actin underlie arthritis-induced muscle weakness.

Skeletal muscle weakness is a prominent clinical feature in patients with rheumatoid arthritis (RA), but the underlying mechanism(s) is unknown. Here we investigate the mechanisms behind arthritis-induced skeletal muscle weakness with special focus on the role of nitrosative stress on intracellular Ca(2+) handling and specific force production