Of Cats And Men: Origins of Primate Color Vision Pathways

color visionneurophysiologylateral geniculate nucleusMost non primate mammals are known to possess dichromatic color vision based on short-wavelength-sensitive (S) and medium/long-wavelength-sensitive (ML) cone photoreceptors. However, the neural pathways carrying signals underlying the primitive “blue–yellow” axis of color vision are largely unexplored in these animals. We have recently characterized a population of color opponent blue- ON cells in electrophysiological single-cell recordings from the dorsal lateral geniculate nucleus (LGN) of anaesthetized cats. We found remarkable similarities to previous descriptions of primate blue-ON cells in terms of receptive field size and structure and the relative weight of functional inputs from the opponent cone classes. Moreover, cat blue- ON cells were found in the same layers as W-cells, which are thought to be homologous to the primate koniocellular system. The temporal frequency optimum of cat blue-ON cells was around 3 Hz, about one-third of that found in achromatic cells. Based on these data, we suggest that cat blue-ON cells are part of a "blue-yellow" color opponent system that is the evolutionary homologue of the blue-ON division of the koniocellular pathway in primates

Etikai normák érvényesülése az EJEB asszisztált öngyilkossággal kapcsolatos gyakorlatában

Az Emberi Jogok Európai Egyezményének (EJEE) 19. cikke értelmében az Emberi Jogok Európai Bíróságát (EJEB) az egyezményben és az ahhoz kapcsolódó jegyzőkönyvekben vállalt kötelezettségek tiszteletben tartásának biztosítása céljából hozták létre. Feladata annak eldöntése, hogy az adott ügyben érintett állam vajon teljesítette-e a vállalt nemzetközi jogi kötelezettségeit. Ennek során a testület elsődlegesen az említett instrumentumokban foglalt rendelkezések hatályát és alkalmazásának körét állapítja meg. A bíróság azonban nem pusztán – az államok többségi álláspontjával egyezően – értelmezi a releváns normákat, hanem az emberi jogok egyfajta morális értelmezését adja. A testület feltárja az esethez kapcsolódó jogok mögötti erkölcsi igazságot, ily módon pedig érvényre juttatja a normák részét képező erkölcsi parancsokat

Az Ovideói egyezmény 5. cikkében foglalt tájékozott beleegyezéshez való jog és az Emberi Jogok Európai Bíróságának vonatkozó gyakorlata

A bioetika egyik meghatározó és fontos alapelve az autonómia tisztelete. Az autonómia, a cselekedet szabadsága, ami azt foglalja magában, hogy az egyén mérlegelheti cselekvésének alternatíváit és azok ismerete alapján, szabadon kiválaszthatja közülük a számára elfogadhatót és annak megfelelően járhat el. Az autonómia tiszteletben tartása ezért az ember értékének, döntéshozatali jogának elismerését és az autonóm cselekvés lehetővé tételét jelenti

A kék csapokból kiinduló vizuális pálya Primates alatti emlősökben = The blue-cone driven visual pathway in non-primate mammals

A projekt témája a színlátás ősi, főemlős alatti emlősökben meglévő mechanizmusának vizsgálata volt elsősorban elektrofiziológiai módszerekkel. Kísérleteinkben csap-specifikus ingerek által kiváltott egysejt-válaszokat mértünk altatott házimacskák corpus geniculatum laterale magjában. Felfedeztünk egy színlátásra optimalizált sejtpopulációt, mely a retinális kék csapoktól ON, a zöld csapoktól OFF típusú bemenetet kap. Receptív mezőik kb. háromszor nagyobbak, mint az akromatikus sejtekéi és a kék- és zöld-csap eredetű komponensek kiterjedése és súlya hasonló. E sejtek számos funkcionális és anatómiai sajátsága a főemlősök kék-ON sejtjeivel fennálló evolúciós homológiára utal, ami alapján feltehető, hogy főemlősök kék-sárga színopponens csatornája az általunk jellemzetthez hasonló, ősi színlátó rendszerből fejlődött ki. További elektrofiziológiai vizsgálatainkhoz kifejlesztettünk és sikeresen teszteltünk egy új, 7-csatornás mélyagyi mikroelektródát, amellyel hatékonyan növelhető az egyszerre jellemezhető neuronok száma. Végül morfometriai tanulmányt végeztünk macska retina fotoreceptor mozaikján annak vizsgálatára, hogy a kék-ON sejtek receptív mezői létrejöhetnek-e a csapok és potenciális szinaptikus partnereik közti véletlen huzalozással. Számításaink szerint a macska retinában léteznie kell egy specifikus kék-csap bipoláris sejttípusnak, valamint a kék-csapok szinaptikus súlya valószínűleg jóval nagyobb, mint az sűrűségükből következne. | We studied the ancient mechanism of colour vision found in non-primate mammals using mainly electrophysiological methods. We measured single-cell responses to cone-isolating visual stimuli in the lateral geniculate nucleus of anaesthetised cats. We discovered a cell population optimised for colour vision, which receives ON-type input from retinal blue-cones and OFF-type input from green-cones. The receptive fields are about 3 times larger than those of achromatic cells and the blue- and green-cone components are matched in size and weight. Several functional and anatomical properties of these cells point to evolutionary homology with blue-ON cells of primates suggesting that the blue-yellow chromatic opponent channel of primates developed from an ancient colour vision system similar to the one characterised by us. To promote our on-going electrophysiological studies, we developed and successfully tested a novel 7-channel deep brain microelectrode allowing a significant increase in the number of simultaneously characterised neurones. Finally, we performed a morphometric study of the cat photoreceptor mosaic to find out if the receptive fields of blue-ON cells can emerge as a result of random wiring between cones and their potential synaptic partners. Our calculations suggest that a specific blue-cone bipolar cell type must exist in the cat retina. Furthermore, the synaptic weight of S-cones is probably considerably higher than expected from their density

Cardioprotection by remote ischemic preconditioning of the rat heart is mediated by extracellular vesicles

Remote ischemic preconditioning (RIPC) of the heart is exerted by brief ischemic insults affected on a remote organ or a remote area of the heart before a sustained cardiac ischemia. To date, little is known about the inter-organ transfer mechanisms of cardioprotection by RIPC. Exosomes and microvesicles/microparticles are vesicles of 30-100nm and 100-1000nm in diameter, respectively (collectively termed extracellular vesicles [EVs]). Their content of proteins, mRNAs and microRNAs, render EVs ideal conveyors of inter-organ communication. However, whether EVs are involved in RIPC, is unknown. Therefore, here we investigated whether (1) IPC induces release of EVs from the heart, and (2) EVs are necessary for cardioprotection by RIPC. Hearts of male Wistar rats were isolated and perfused in Langendorff mode. A group of donor hearts was exposed to 3x5-5min global ischemia and reperfusion (IPC) or 30min aerobic perfusion, while coronary perfusates were collected. Coronary perfusates of these hearts were given to another set of recipient isolated hearts. A group of recipient hearts received IPC effluent depleted of EVs by differential ultracentrifugation. Infarct size was determined after 30min global ischemia and 120min reperfusion. The presence or absence of EVs in perfusates was confirmed by dynamic light scattering, the EV marker HSP60 Western blot, and electron microscopy. IPC markedly increased EV release from the heart as assessed by HSP60. Administration of coronary perfusate from IPC donor hearts attenuated infarct size in non-preconditioned recipient hearts (12.9+/-1,6% vs. 25.0+/-2.7%), similarly to cardioprotection afforded by IPC (7.3+/-2.7% vs. 22.1+/-2.9%) on the donor hearts. Perfusates of IPC hearts depleted of EVs failed to exert cardioprotection in recipient hearts (22.0+/-2.3%). This is the first demonstration that EVs released from the heart after IPC are necessary for cardioprotection by RIPC, evidencing the importance of vesicular transfer mechanisms in remote cardioprotection

Temporal Processing of Cyclopean Stimuli: A Psychophysical Study

In the clinical practice, the evaluation of binocular vision is carried out with the traditional Worth-4-dot test, which is based on his classic theory, suggesting three hierarchical stages of stereovision (Worth, 1906). However, according to research nowadays, binocular vision rather involves parallel pathways. We do not know how the hierarchical organizational principles set forward in the Worth model can be related to the parallel processing pathway theory. We aimed to use reaction time (RT) measurement, a traditional psychophysical method, in a series of experiments, to examine the processing time of mechanisms in stereovision by using different types of cyclopean stimuli that are only visible binocularly by individuals who have intact stereopsis. We tested the effect of correlation, disparity and contrast on RT. Overall, the results suggest that the processing of cyclopean stimuli is more time consuming than non-cyclopean ones and that the speed further depends on the disparity and contrast of the stimuli. We have failed to prove that the processing of the different types of cyclopean stimuli takes a hierarchical order, rather, the results support the idea of parallel systems

Isolation of Exosomes from Blood Plasma: Qualitative and Quantitative Comparison of Ultracentrifugation and Size Exclusion Chromatography Methods

BACKGROUND: Exosomes are emerging targets for biomedical research. However, suitable methods for the isolation of blood plasma-derived exosomes without impurities have not yet been described. AIM: Therefore, we investigated the efficiency and purity of exosomes isolated with potentially suitable methods; differential ultracentrifugation (UC) and size exclusion chromatography (SEC). METHODS AND RESULTS: Exosomes were isolated from rat and human blood plasma by various UC and SEC conditions. Efficiency was investigated at serial UC of the supernatant, while in case of SEC by comparing the content of exosomal markers of various fractions. Purity was assessed based on the presence of albumin. We found that the diameter of the majority of isolated particles fell into the size range of exosomes, however, albumin was also present in the preparations, when 1h UC at 4 degrees C was applied. Furthermore, with this method only a minor fraction of total exosomes could be isolated from blood as deduced from the constant amount of exosomal markers CD63 and TSG101 detected after serial UC of rat blood plasma samples. By using UC for longer time or with shorter sedimentation distance at 4 degrees C, or UC performed at 37 degrees C, exosomal yield increased, but albumin impurity was still observed in the isolates, as assessed by transmission electron microscopy, dynamic light scattering and immunoblotting against CD63, TSG101 and albumin. Efficiency and purity were not different in case of using further diluted samples. By using SEC with different columns, we have found that although a minor fraction of exosomes can be isolated without significant albumin content on Sepharose CL-4B or Sephacryl S-400 columns, but not on Sepharose 2B columns, the majority of exosomes co-eluted with albumin. CONCLUSION: Here we show that it is feasible to isolate exosomes from blood plasma by SEC without significant albumin contamination albeit with low vesicle yield