Guest Editorial - Motor skill learning and neuro-rehabilitation

The six articles in this special section present novel rehabilitation and assistive techniques that are directly related to motor learning concepts

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Razlike u periodu rehabilitacije kod dve tehnike grafta za rekonstrukciju prednje ukr{tene veze (LCA): tetive semitendinozus / gracilis – ligament patel

Original scientific paper

The effect of reversing current deposition on the apparent density of electrolytic copper powde

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Profesionalni traumatizam je jedan od naju~estaliji

Original scientific paper

The protolytic equilibria of bromazepam, an ampholyte sparingly soluble in water, in homogeneous and heterogeneous systems were studied in the pH range 0–14 at 25 ºC and at ionic strength of 0.1 mol/dm3 (NaCl). On the basis of 13C-NMR spectra, the protonation site was predicted – in acidic media the pyridine nitrogen of bormazepam is protonated. The acidity constants of bromazepam were determined spectrophotometrically (pKa1 2.83 and pKa2 11.60) and potentiometrically (pKa1 2.99). In the heterogeneous system the following equilibrium constants were determined: Ks0 = �HA � (pKs0 3.44), Ks1 = �H2A + �/�H3O + � (pKs1 0.61), and Ks2 = �A-��H3O + � (pKs2 15.04)

Glutamic acid 242 is a valve in the proton pump of cytochrome c oxidase

Aerobic life is based on a molecular machinery that utilizes oxygen as a terminal electron sink. The membrane-bound cytochrome c oxidase (CcO) catalyzes the reduction of oxygen to water in mitochondria and many bacteria. The energy released in this reaction is conserved by pumping protons across the mitochondrial or bacterial membrane, creating an electrochemical proton gradient that drives production of ATP. A crucial question is how the protons pumped by CcO are prevented from flowing backwards during the process. Here, we show by molecular dynamics simulations that the conserved glutamic acid 242 near the active site of CcO undergoes a protonation state-dependent conformational change, which provides a valve in the pumping mechanism. The valve ensures that at any point in time, the proton pathway across the membrane is effectively discontinuous, thereby preventing thermodynamically favorable proton back-leakage while maintaining an overall high efficiency of proton translocation. Suppression of proton leakage is particularly important in mitochondria under physiological conditions, where production of ATP takes place in the presence of a high electrochemical proton gradient