A humán szemlencse UV abszorbanciájának változása az életkor függvényében = Age-dependent UV absorbance of the human ocular lens

A szemlencse jelentős mennyiségű UV sugárzást képes elnyelni. A tanulmány célja a humán szemlencse UV elnyelő képességének vizsgálata, különös tekintettel a lencse különböző rétegeinek UV abszorbanciájára és az abszorbancia korfüggő változásaira. Különböző korú humán cadaver szemlencsékből 60 µm vastag metszeteket készítettünk és mindegyik metszet UV abszorbanciáját megmértük egy pásztázó spektrophotométerrel. Az elülső és ahátsó lencsetok, valamint tenyésztett lencse epithelium abszorbanciáját is meghatároztuk. A vizsgált lencsékben az UV-B és UV-C tartományban az abszorpció növekedett a lencse hátsó felszíne felé. Az abszorpció növekedése független volt a lencse szerkezetétől. Idősebb lencsék több UV sugárzást nyeltek el, mint a fiatalabb lencsék. Az elülső és a hátsó lencsetok, valamint a lencsetok hámja jelentős UV abszorpciós együtthatóval rendelkezett az UV-C tartományban. Eredményeink szerint a humán szemlencse jelentős UV abszorpciós hatással rendelkezik. Ez a hatás a korral nő, feltehetőleg a lencsében felhalmozódó chromophor molekulák miatt. Vizsgálataink megerősítik a feltételezést, hogy a szemlencse mögötti képleteket nem éri jelentős mennyiségű sugárzás átlagos UV terhelés setében. | The lens is able to absorb significant amount of ultraviolet (UV) radiation. In this study we wanted to investigate what parts of the human lens are most effective in UV absorbance and whether the UV absorbance is affected by age. Consecutive slices (60 µm) of human cadaveric lenses of various age were cut and the UV absorbance of each sample was determined using a scanning spectrophotometer. The absorbance of the anterior and posterior lens capsules and that of cultured lens epithelium were also measured. Our data show that the UV-C and UV-B absorption of the human lens increases towards the posterior parts of the lens unrelated to the anatomical structure of the lens. Older lenses absorbed more UV radiation than younger lenses. Moreover, the lens epithelium, the anterior and posterior lens structures were also effective absorbers of UV-C radiation. These results suggest that the human lens has a very strong UV filtering effect and this effect increases with age possibly due to the increased amount of various chromophor molecules deposited in the lens. Our data suggest that no significant amount of UV-B and UV-C radiation is able to reach the ocular structures behind the lens in case of average UV radiation

The Role of Metals in the Neuroregenerative Action of BDNF, GDNF, NGF and Other Neurotrophic Factors

Mature neurotrophic factors and their propeptides play key roles ranging from the regulation of neuronal growth and differentiation to prominent participation in neuronal survival and recovery after injury. Their signaling pathways sculpture neuronal circuits during brain development and regulate adaptive neuroplasticity. In addition, neurotrophic factors provide trophic support for damaged neurons, giving them a greater capacity to survive and maintain their potential to regenerate their axons. Therefore, the modulation of these factors can be a valuable target for treating or preventing neurologic disorders and age-dependent cognitive decline. Neuroregenerative medicine can take great advantage by the deepening of our knowledge on the molecular mechanisms underlying the properties of neurotrophic factors. It is indeed an intriguing topic that a significant interplay between neurotrophic factors and various metals can modulate the outcome of neuronal recovery. This review is particularly focused on the roles of GDNF, BDNF and NGF in motoneuron survival and recovery from injuries and evaluates the therapeutic potential of various neurotrophic factors in neuronal regeneration. The key role of metal homeostasis/dyshomeostasis and metal interaction with neurotrophic factors on neuronal pathophysiology is also highlighted as a novel mechanism and potential target for neuronal recovery. The progress in mechanistic studies in the field of neurotrophic factor-mediated neuroprotection and neural regeneration, aiming at a complete understanding of integrated pathways, offers possibilities for the development of novel neuroregenerative therapeutic approaches

Motoneuronal inflammasome activation triggers excessive neuroinflammation and impedes regeneration after sciatic nerve injury

Peripheral nerve injuries are accompanied by inflammatory reactions, over-activation of which may hinder recovery. Among pro-inflammatory pathways, inflammasomes are one of the most potent, leading to release of active IL-1β. Our aim was to understand how inflammasomes participate in central inflammatory reactions accompanying peripheral nerve injury.After axotomy of the sciatic nerve, priming and activation of the NLRP3 inflammasome was examined in cells of the spinal cord. Regeneration of the nerve was evaluated after coaptation using sciatic functional index measurements and retrograde tracing.In the first 3 days after the injury, elements of the NLRP3 inflammasome were markedly upregulated in the L4-L5 segments of the spinal cord, followed by assembly of the inflammasome and secretion of active IL-1β. Although glial cells are traditionally viewed as initiators of neuroinflammation, in this acute phase of inflammation, inflammasome activation was found exclusively in affected motoneurons of the ventral horn in our model. This process was significantly inhibited by 5-BDBD, a P2X4 receptor inhibitor and MCC950, a potent NLRP3 inhibitor. Although at later time points the NLRP3 protein was upregulated in microglia too, no signs of inflammasome activation were detected in these cells. Inhibition of inflammasome activation in motoneurons in the first days after nerve injury hindered development of microgliosis in the spinal cord. Moreover, P2X4 or inflammasome inhibition in the acute phase significantly enhanced nerve regeneration on both the morphological and the functional levels.Our results indicate that the central reaction initiated by sciatic nerve injury starts with inflammasome activation in motoneurons of the ventral horn, which triggers a complex inflammatory reaction and activation of microglia. Inhibition of neuronal inflammasome activation not only leads to a significant reduction of microgliosis, but has a beneficial effect on the recovery as well

Riluzole treatment modulates KCC2 and EAAT-2 receptor expression and Ca2+ accumulation following ventral root avulsion injury

Avulsion injury results in motoneuron death due to the increased excitotoxicity developing in the affected spinal segments. This study focused on possible short and long term molecular and receptor expression alterations which are thought to be linked to the excitotoxic events in the ventral horn with or without the anti-excitotoxic riluzole treatment. In our experimental model the left lumbar 4 and 5 (L4, 5) ventral roots of the spinal cord were avulsed. Treated animals received riluzole for 2 weeks. Riluzole is a compound that acts to block voltageactivated Na+ and Ca2+ channels. In control animals the L4, 5 ventral roots were avulsed without riluzole treatment. Expression of astrocytic EAAT-2 and that of KCC2 in motoneurons on the affected side of the L4 spinal segment were detected after the injury by confocal and dSTORM imaging, intracellular Ca2+ levels in motoneurons were quantified by electron microscopy. The KCC2 labeling in the lateral and ventrolateral parts of the L4 ventral horn was weaker compared with the medial part of L4 ventral horn in both groups. Riluzole treatment dramatically enhanced motoneuron survival but was not able to prevent the down-regulation of KCC2 expression in injured motoneurons. In contrast, riluzole successfully obviated the increase of intracellular calcium level and the decrease of EAAT-2 expression in astrocytes compared with untreated injured animals. We conclude that KCC2 may not be an essential component for survival of injured motoneurons and riluzole is able to modulate the intracellular level of calcium and expression of EAAT-2

Ex vivo infection of human embryonic spinal cord neurons prior to transplantation into adult mouse cord

<p>Abstract</p> <p>Background</p> <p>Genetically modified pseudorabies virus (Prv) proved suitable for the delivery of foreign genes to rodent embryonic neurons <it>ex vivo </it>and maintaining foreign gene expression after transplantation into spinal cord in our earlier study. The question arose of whether human embryonic neurons, which are known to be more resistant to Prv, could also be infected with a mutant Prv. Specifically, we investigated whether a mutant Prv with deleted ribonucleotide reductase and early protein 0 genes has the potential to deliver marker genes (gfp and β-gal) into human embryonic spinal cord neurons and whether the infected neurons maintain expression after transplantation into adult mouse cord.</p> <p>Results</p> <p>The results revealed that the mutant Prv effectively infected human embryonic spinal cord neurons <it>ex vivo </it>and the grafted cells exhibited reporter gene expression for several weeks. Grafting of infected human embryonic cells into the spinal cord of immunodeficient (rnu-/rnu-) mice resulted in the infection of some of the host neurons.</p> <p>Discussion</p> <p>These results suggest that Prv is suitable for the delivery of foreign genes into transplantable human cells. This delivery method may offer a new approach to use genetically modified cells for grafting in animal models where spinal cord neuronal loss or axon degeneration occurs.</p

Motoneuronal inflammasome activation triggers excessive neuroinflammation and impedes regeneration after sciatic nerve injury

Peripheral nerve injuries are accompanied by inflammatory reactions, over-activation of which may hinder recovery. Among pro-inflammatory pathways, inflammasomes are one of the most potent, leading to release of active IL-1β. Our aim was to understand how inflammasomes participate in central inflammatory reactions accompanying peripheral nerve injury.After axotomy of the sciatic nerve, priming and activation of the NLRP3 inflammasome was examined in cells of the spinal cord. Regeneration of the nerve was evaluated after coaptation using sciatic functional index measurements and retrograde tracing.In the first 3 days after the injury, elements of the NLRP3 inflammasome were markedly upregulated in the L4-L5 segments of the spinal cord, followed by assembly of the inflammasome and secretion of active IL-1β. Although glial cells are traditionally viewed as initiators of neuroinflammation, in this acute phase of inflammation, inflammasome activation was found exclusively in affected motoneurons of the ventral horn in our model. This process was significantly inhibited by 5-BDBD, a P2X4 receptor inhibitor and MCC950, a potent NLRP3 inhibitor. Although at later time points the NLRP3 protein was upregulated in microglia too, no signs of inflammasome activation were detected in these cells. Inhibition of inflammasome activation in motoneurons in the first days after nerve injury hindered development of microgliosis in the spinal cord. Moreover, P2X4 or inflammasome inhibition in the acute phase significantly enhanced nerve regeneration on both the morphological and the functional levels.Our results indicate that the central reaction initiated by sciatic nerve injury starts with inflammasome activation in motoneurons of the ventral horn, which triggers a complex inflammatory reaction and activation of microglia. Inhibition of neuronal inflammasome activation not only leads to a significant reduction of microgliosis, but has a beneficial effect on the recovery as well

Az agy vérellátásának szabályozása újszülöttkori kísérletes hypoxiában = Regulation of cerebral blood supply following experimentally-induced hypoxia in the newborn

Altatott, újszülött malacokon vizsgáltuk a glutamáterg agyi vazododilatáció mechanizmusát. Megállapítottuk, hogy a kinurensav és a kvinolinsav, melyek a triptofán lebontási termékei befolyásolják az agyi erek NMDA és kainsav iránti érzékenységét. Malac agyból izolált arteriolákat vizsgálva arra a következtetésre jutottunk, hogy a glutamáterg vazodilatáció neuronális elemek közvetítésével jön létre. A mitochondriumok ATP szenzitív K+ csatornára ható diazoxide (DIAZ) segítségével bizonyítottuk, hogy agyi ischemiát követően az érendothelium és a neuronális-vaszkuláris csatolás károsodása mitochondriális eredetű. Patkányban igazoltuk, hogy a DIAZ előkezelés csökkenti az agyi ischemia következményeként létrejövő vér-agy gátkárosodást. Malac agyból nyert izolált mitochondriumokon demonstráltuk. DIAZ depolarizáló hatását, valamint az ezzel együtt jelentkező ROS termelődést. Szelektív enzim gátló szerek segítségével karakterizáltuk a ciklooxigenáz úton termelődő prosztanoidok szerepét az újszülöttkori agyi érreakciókban. Eredményeink szerint az asphyxiát követő 100% oxigénnel történő újraélesztés a hippocampusban és a kisagyban fokozza a neurodegenerációt. Mikrokeringési vizsgálataink rámutattak, hogy ennek lokális hemodinamikai okai lehetnek. Patkányban létrehozott krónikus agyi hipoperfúzió magatartási és morfológiai következményeinek vizsgálata során azt tapasztaltuk, hogy DIAZ előkezeléssel javíthatók a kognitív funkciók és csökken a hippocampális neuronális károsodás is. | In anesthetized newborn piglets we examined the mechanism of the glutamatergic vasodilation. We have shown that two metabolites of the kynurenine pathway of tryptophan degradation acting at the NMDA receptor, the antagonist kynurenic acid (KYNA) and the agonist quinolinic acid are capable of modulating the dilation of pial arterioles. In isolated piglet arteries, we demonstrated the lack of NMDA-induced vascular responses. We demonstrated that diazoxide (DIAZ), an activator of mitochondrial ATP-sensitive K+ (mitoKATP) channels, preserves endothelium-dependent cerebrovascular dilator responses after ischemia-reperfusion but does not affect the damage in the vascular smooth muscle. In a rat model of the cerebral ischemia we have shown that DIAZ pretreatment inhibited the edema formation and the disruption of the blood brain barrier. We characterized the effects of KATP channel openers and blockers on membrane potential and on the production of reactive oxygen species in isolated piglet mitochondria. Using selective enzyme inhibitors we further characterized the role of the cyclooxygenase (COX)-derived prostanoids in the cerebrovascular control of newborns. We demonstrated O2 toxicity after asphyxia was in the piglet hippocampus and cerebellum but not in the cerebral cortex or basal ganglia. The regional differences may be associated with haemodynamic factors. In a rat model of chronic hypoperfusion we demonstrated that pretreatment with DIAZ offers therapeutical prospects

Spatiotemporal Differences in Gene Expression Between Motor and Sensory Autografts and Their Effect on Femoral Nerve Regeneration in the Rat

To improve the outcome after autologous nerve grafting in the clinic, it is important to understand the limiting variables such as distinct phenotypes of motor and sensory Schwann cells. This study investigated the properties of phenotypically different autografts in a 6 mm femoral nerve defect model in the rat, where the respective femoral branches distally of the inguinal bifurcation served as homotopic, or heterotopic autografts. Axonal regeneration and target reinnervation was analyzed by gait analysis, electrophysiology, and wet muscle mass analysis. We evaluated regeneration-associated gene expression between 5 days and 10 weeks after repair, in the autografts as well as the proximal, and distal segments of the femoral nerve using qRT-PCR. Furthermore we investigated expression patterns of phenotypically pure ventral and dorsal roots. We identified highly significant differences in gene expression of a variety of regeneration-associated genes along the central – peripheral axis in healthy femoral nerves. Phenotypically mismatched grafting resulted in altered spatiotemporal expression of neurotrophic factor BDNF, GDNF receptor GFRα1, cell adhesion molecules Cadm3, Cadm4, L1CAM, and proliferation associated Ki67. Although significantly higher quadriceps muscle mass following homotopic nerve grafting was measured, we did not observe differences in gait analysis, and electrophysiological parameters between treatment paradigms. Our study provides evidence for phenotypic commitment of autologous nerve grafts after injury and gives a conclusive overview of temporal expression of several important regeneration-associated genes after repair with sensory or motor graft