Autonomous navigation system for the Marsokhod rover project

This paper presents a general overview of the Marsokhod rover mission. The autonomous navigation for a Mars exploration rover is controlled by a vision system which has been developed on the basis of two CCD cameras, stereovision and path planning algorithms. Its performances have been tested on a Mars-like experimentation site

Ryanodine receptor leak triggers fiber Ca²⁺ redistribution to preserve force and elevate basal metabolism in skeletal muscle

Muscle contraction depends on tightly regulated Ca2+ release. Aberrant Ca2+ leak through ryanodine receptor 1 (RyR1) on the sarcoplasmic reticulum (SR) membrane can lead to heatstroke and malignant hyperthermia (MH) susceptibility, as well as severe myopathy. However, the mechanism by which Ca2+ leak drives these pathologies is unknown. Here, we investigate the effects of four mouse genotypes with increasingly severe RyR1 leak in skeletal muscle fibers. We find that RyR1 Ca2+ leak initiates a cascade of events that cause precise redistribution of Ca2+ among the SR, cytoplasm, and mitochondria through altering the Ca2+ permeability of the transverse tubular system membrane. This redistribution of Ca2+ allows mice with moderate RyR1 leak to maintain normal function; however, severe RyR1 leak with RYR1 mutations reduces the capacity to generate force. Our results reveal the mechanism underlying force preservation, increased ATP metabolism, and susceptibility to MH in individuals with gain-of-function RYR1 mutations

Human skeletal muscle plasmalemma alters its structure to change its Ca2+-handling following heavy-load resistance exercise

High-force eccentric exercise results in sustained increases in cytoplasmic Ca2+ levels ([Ca2+]cyto), which can cause damage to the muscle. Here we report that a heavy-load strength training bout greatly alters the structure of the membrane network inside the fibres, the tubular (t-) system, causing the loss of its predominantly transverse organization and an increase in vacuolation of its longitudinal tubules across adjacent sarcomeres. The transverse tubules and vacuoles displayed distinct Ca2+-handling properties. Both t-system components could take up Ca2+ from the cytoplasm but only transverse tubules supported store-operated Ca2+ entry. The retention of significant amounts of Ca2+ within vacuoles provides an effective mechanism to reduce the total content of Ca2+ within the fibre cytoplasm. We propose this ability can reduce or limit resistance exercise-induced, Ca2+-dependent damage to the fibre by the reduction of [Ca2+]cyto to help maintain fibre viability during the period associated with delayed onset muscle soreness

Les monnaies grecques

Il volume presenta le monete greche conservate nel medagliere della biblioteca municipale di Grenoble. Sono presenti tutte le zecche d'area mediterranea con un maggior quantitativo di emissioni della Gallia (essenzialmente di Marsiglia e della valle del Rhone), d'Italia meridionale, di Sicilia e dell'Africa punica. Si rileva, dunque, una dominante occidentale che consente alcune ipotesi sulle modalità di formazione della collezione

TECHNICAL NOTE: NON INVASIVE METHOD TO PROTECT THE EXTERNAL PART OF CATHETERS OR FLOW PROBES CHRONICALLY IMPLANTED IN RABBITS

[EN] This technical note describe the steps of fabrication of a protective backpack for the extemal part of catheters or flow probes chronically implantad in rabbits. This backpack is made with fabric and velera®, and the straps are made with electric wire which cannot be nibbled by the animal. This method is non invasiva and does not modify the animal behaviour (caecotrophy, suckling, washing .... ).[FR] Note technique : Méthode non invasive de protection de l'extrémité externe des catheters et des sondes débitrnétriques implantés en chronique chez le lapin. Cette note technique décrit les étapes de fabrication d'un sac a dos pour lapin permettant de protéger de fayon efficace l'extrémité de cathéters ou de sondes débitmétriques implantés en chronique. Ce sac ti dos est fabriqué ti l'aide de tissu et de velero®, les bretelles sont en fil électrique et ne peuvent pas étre grignotées par l'animal. Cette méthode présente l'avantage d'étre non invasiva et ne modifie pas le comportement de l'animal (caecotrophie, allaitement, toilette .. ).Fortun-Lamothe, L.; Lamboley-Gaüzere, B. (1998). TECHNICAL NOTE: NON INVASIVE METHOD TO PROTECT THE EXTERNAL PART OF CATHETERS OR FLOW PROBES CHRONICALLY IMPLANTED IN RABBITS. World Rabbit Science. 06(2). doi:10.4995/wrs.1998.354SWORD06

Skeletal muscle fibre swelling contributes to force depression in rats and humans: a mechanically-skinned fibre study

This study investigated the effects of fibre swelling on force production in rat and human skinned muscle fibres, using osmotic compression to reverse the fibre swelling. In mechanically-skinned fibres, the sarcolemma is removed but normal excitation–contraction coupling remains functional. Force responses in mechanically-skinned fibres were examined with and without osmotic compression by polyvinylpyrrolidone 40\ua0kDa (PVP-40) or Dextran 500\ua0kDa (dextran). Fibre diameter increased to 116 ± 2% (mean ± SEM) when rat skinned type II fibres were immersed in the standard intracellular solution, but remained close to the in situ size when 3% (mass/volume) PVP-40 or 4% Dextran were present. Myofibrillar Ca sensitivity, as indicated by pCa (−\ua0log[Ca] at half-maximal force), was increased in 4% Dextran (0.072 ± 0.007 pCa shift), but was not significantly changed in 3% PVP-40. Maximum Ca-activated force increased slightly to 103 ± 1% and 104 ± 1% in PVP-40 and Dextran, respectively. Both tetanic and depolarization-induced force responses in rat skinned type II fibres, elicited by electrical stimulation and ion substitution respectively, were increased by ~ 10 to 15% when the fibres were returned to their normal in situ diameter by addition of PVP-40 or Dextran. Interestingly, the potentiation of these force responses in PVP-40 was appreciably greater than could be explained by potentiation of myofibrillar function alone. These results indicate that muscle fibre swelling, as can occur with intense exercise, decreases evoked force responses by reducing both the Ca-sensitivity of the contractile apparatus properties and Ca release from the sarcoplasmic reticulum