The effects of mossy fiber cerebral and spinal inputs on cerebellar purkinje cells

In unanesthetized cats (treated with analgesic), field potentials and responses of single Purkinje cells in the rostral folia of the paramedian lobule of the cerebellum (the cerebellar forelimb area) were recorded following stimulation both of the forelimb area in the primary sensorimotor cerebral cortex and of the forelimb nerves. Only short latency responses produced by mossy fiber inputs were studied. The component of field potentials generated by granule cells, as well as the reactions of individual Purkinje cells, were found to be more pronounced in case of cerebral than of nerve stimulation. Although individual Purkinje cells were more strongly activated by the sensorimotor cortex than by the nerves, the field potentials generated by Purkinje cells in response to both cerebral and nerve stimulations were similar in size. The reversal of the polarity of the potentials generated by Purkinje cells took place somewhat deeper in the cerebellar cortex in case of the cerebral than of the nerve stimulation.Theoretical analysis of the field potentials has shown that the differences in responses to cerebral and nerve stimulations are accounted for by the fact that mossy fibers of the cerebral input terminate deeper in the granular layer and, thus, cause more proximal depolarization of Purkinje cell dendrites than fibers of the spinal input.     

The projection of the temporal retina in rats,studied by retrograde transport of horseradish peroxidase

Summary Horseradish peroxidase (HRP) was injected unilaterally into the lateral geniculate nucleus or tectum, or both, in 26 hooded rats in order to mark the exact extent of the retina from which uncrossed optic axons arise. This region occupied about a quarter of the retina, in the temporal periphery, following thalamic injections, but a much smaller region following tectal injections. By comparing the proportions of HRP positive neurones in nasal and temporal retinae of both eyes it was shown that: (1) within the region supplying uncrossed axons the majority of the ganglion cells nevertheless project contralaterally, (2) a large proportion of the ganglion cells from the temporal crescent project bilaterally, which does not occur from the remainder of the retina, (3) ganglion cells of all sizes contribute to both ipsilateral and contralateral projections. The results also support earlier suggestions that the smallest neurones in the ganglion cell layer do not send an axon into the brain, and are therefore not ganglion cells     

不同年龄组人视网膜微血管内皮细胞特性的研究(英文)

目的：研究2个不同年龄组供体来源的人视网膜微血管内皮细胞的特性。方法： 分离培养2个不同年龄组的人视网膜微血管内皮细胞,分别为出生后30 d内和40-65岁供体组。视网膜微血管内皮细胞具有特异性表达,通过免疫荧光染色CD31、vWF和乙酰化低密度脂蛋白(Dil-Ac-LDL)的摄取来定位内皮细胞的标记。通过使用matrigel基质胶培养细胞,激光共聚焦显微镜和Western blotting分析vWF在细胞内的分布,评估2组细胞管状结构形成能力以及vWF在细胞内的不同分布。结果： 从2个不同年龄组中成功地获得高纯度视网膜微血管内皮细胞。2组在种到基质胶后6 h均能形成典型的二维管腔样结构,但婴幼儿组评分比成人组高（27.2％±2.2％）,且二维管腔样结构在30 h仍可较好地维持,而成人组已看到部分自发降解。另外可见到vWF在婴幼儿组主要表达在细胞核内,而成人组主要表达在胞浆。结论： 不同年龄来源的人视网膜血管内皮细胞具有某些自身特定的性状特征,在与年龄相关的疾病的体外研究中,供体年龄因素可能造成的影响应该得到一定的重视。     

Calbindin immunoreactivity in the developing and adult human cerebellum

Calbindin (CALB), a calcium-binding protein, is known to be expressed in the embryonic nervous system. In this study, we have examined its distribution in the cerebellum of human fetuses (11–25 weeks of gestation) and adult by immunohistochemistry. At the gestational age of 11–12 weeks, CALB immunoreactivity was present in granule and Purkinje cells throughout the cerebellum. By 16–21 weeks of gestation, immunoreactive Purkinje cells were well-differentiated in the vermis and flocculus, and their axons ran towards the deep cerebellar nuclei area, while the axon collaterals were seen to be distributed into adjacent folia. At the gestational period of 24–25 weeks, most Purkinje cells of the flocculus and vermis were arranged in one to two rows, while those of the hemispheres were still undifferentiated. A few Golgi cells of the vermis showed immunoreactivity. The neurons of the deep nuclei were immunonegative right from the gestational age of 11 weeks although a fine stippled staining of fibers was present throughout the body of all nuclei. The fibers lying close to the hilum of the dentate nucleus were strongly CALB-positive. The vestibulocerebellar fibers, being traced at the level of lower pons and upper medulla oblongata were stained as early as 11 weeks of gestation, whereas the olivocerebellar fibers were stained from 16 weeks onward. In the adult cerebellum, Purkinje cells were moderately immunopositive while granule cells were faintly stained; no other cells, including those of the deep nuclei were stained. In the medulla oblongata, the inferior olivary nucleus and olivocerebellar fibers were strongly CALB-positive. Our results indicate that CALB is expressed in early migratory Purkinje cells, and their maturation occurs in a vermal-to-hemisphere gradient. It is likely that CALB plays a significant role in the regulation of Ca²⁺-dependent activities in the developing cerebellum.     

Presence of satellite cells in a cardiac rhabdomyoma

Cardiac rhabdomyoma is the most common tumour of the heart in infancy and childhood. The clinical presentation, diagnosis and histopathological characteristics have been extensively studied; however, reports on the ultrastructure and histogenesis of this lesion are scanty and inconclusive. The case to be discussed is that of a 10-year-old male who presented with a cardiac rhabdomyoma occupying almost the entire ventricular apex. Ultrastructurally, the rhabdomyoma cells have a central, deeply-indented nucleus surrounded by an admixture of mitochondria and sarcomeres. The remainder of the cytoplasm is occupied by pools of glycogen granules, randomly-orientated myofibrils and small mitochondria. Intercellular junctions are numerous and consist of alternating zonula occludens and macula adherens. Typical satellite cells, sharing a common basement lamina are seen apposed to the rhabdomyoma cells. It is tempting to postulate that the proliferation of the rhabdomyoma cells is accomplished by differentiation of satellite cells, a process known to occur in skeletal muscle. Ultrastructurally, the rhabdomyoma cells are indistinguishable from Purkinje cells. The presence of Purkinje-like cells in ectopic locations within the heart and their association with satellite cells is likely a form of embryological atavism.     

The ultrastructure of Purkinje cells in diphenylhydantoin intoxicated rats

Summary Electron microscopic examination of Purkinje Cells was performed in sections from the cerebellum of three albino rats aged 4 1/2 month, intoxicated with diphenylhydantoin for 51 days. Three untreated albino rats served as controls.There were no difference between the substructure of the Purkinje cells from the two groups of animals.It was concluded that diphenylhydantoin in toxic but sublethal doses does not change the substructure of the Purkinje cells.This work was supported by grant from the Danish Epilepsy Association and the Danish Medical Research Council.     

Nasotemporal overlap in the human retina investigated by means of simple reaction time to lateralized light flash

Summary When light flashes are presented laterally simple vocal and manual responses are faster to stimuli in the visual half-field having direct access to the responding hemisphere (an uncrossed reaction) than stimuli which go initially to the nonresponding hemisphere (a crossed reaction). In the latter case an interhemispheric crossing is presumably necessary and so the crossed-minus-uncrossed difference (CUD) can be identified with interhemispheric transmission time. This paradigm was used to investigate the problem of whether or not there is an overlap of ipsi- and contralaterally projecting ganglion cells at the border between nasal and temporal areas of the human retina, resulting in dual representation of the midline in the brain. If such an overlap does exist then presenting stimuli on this region ought to result in an abolition of the CUD since information would be equally available to both hemispheres. Accordingly vocal and manual reaction times to flashes presented at 1/2, 1, 2, and 4 deg of visual angle were measured. In both cases a consistent CUD was found and this was present at all four points. These results are interpreted as arguing against the existence of overlap in man though some alternative possibilities are discussed.Supported by the British Council and the European Science Foundation by means of twinning grants with the Universities of Pisa and Parma, Italy     

The morphological correlates of X- and Y-like retinal ganglion cells in the retina of monkeys

Summary The morphology of the ganglion cells of the monkey's retina was revealed by filling the cells with horseradish peroxidase from their cut axons in the optic nerve. This procedure gave much more consistent results than the Golgi method, was much quicker and filled dendrites just as extensively. Quantitative measures of the dendritic tree of two types of ganglion cell, P and P, suggest that they correspond to the physiologically defined Y- and X-cells, respectively.Supported by MRC grant G971/397/B     

The cytotoxicity of cadmium-based quantum dots

Semiconductor Quantum dots (QDs) have raised great attention because of their superior optical properties and wide utilization in biological and biomedical studies. More recently, there have been intense concerns on cytotoxicity assessment of QDs. Most QDs are made of heavy metal ions (e.g., Cd²⁺), which may result in potential in vitro toxicity that hampers their practical applications. In this article, we aim to summarize recent progress on mechanistic studies of cytotoxicity of II-IV QDs. We have studied the cytotoxicity of a series of aqueous synthesized QDs (aqQDs), i.e. CdTe, CdTe/CdS core-shell structured and CdTe/CdS/ZnS core-shell-shell structured aqQDs. Our results suggested that released cadmium ions are responsible for the observed cytotoxicity of cadmium-based QDs. The fact that CdTe/CdS/ZnS core-shell-shell structured QDs are nearly nontoxic to cells further confirmed the role of released cadmium ions on cytotoxicity, and the effective protection of the ZnS shell. However, intracellular level of Cd²⁺ ions cannot be the only reason since the comparison with CdCl₂-treated cells suggests there are other factors contributed to the cytotoxicity of aqQDs. Our studies on genome-wide gene expression profiling and subcellular localization of aqQDs with synchrotron-based scanning transmission X-ray microscopy (STXM) further suggest that the cytotoxicity of CdTe QDs not only comes from the release of Cd²⁺ ions but also intracellular distribution of QD nanoparticles in cells and the associated nanoscale effects.     

Analysis of spike trains in terms of delayed coincidences

Summary A particular correlation technique was used in order to analyse the spontaneous electrical activity of neurons in the frog's brain, and an electronic device was constructed for analysis of available data. On the basis of the correlograms obtained, two simple models of the net in the neighbourhood of the neuron studied are suggested as explanations for the observed regularities in the spike trains.The present research has been sponsored in part by AF EOAR-6625.     

In vivo quantum dot labeling of mammalian stem and progenitor cells.

Fluorescent semiconductor nanocrystal quantum dots (QDs) are a class of multifunctional inorganic fluorophores that hold great promise for clinical applications and biomedical research. Because no methods currently exist for directed QD-labeling of mammalian cells in the nervous system in vivo, we developed novel in utero electroporation and ultrasound-guided in vivo delivery techniques to efficiently and directly label neural stem and progenitor cells (NSPCs) of the developing mammalian central nervous system with QDs. Our initial safety and proof of concept studies of one and two-cell QD-labeled mouse embryos reveal that QDs are compatible with early mammalian embryonic development. Our in vivo experiments further show that in utero labeled NSPCs continue to develop in an apparent normal manner. These studies reveal that QDs can be effectively used to label mammalian NSPCs in vivo and will be useful for studies of in vivo fate mapping, cellular migration, and NSPC differentiation during mammalian development.     

Congenital “histiocytoid” cardiomyopathy: Evidence suggesting a developmental disorder of the purkinje cell system of the heart

Summary The so-called histiocytoid cardiomyopathy is an unusual cardiac disorder of infancy and childhood, characterized by the presence of numerous foamy, lipid-containing cells between the endocardium and the striated myocardial cells of the left ventricle and the interventricular septum. The disease usually affects females, the clinical picture being dominated by severe disturbances of conduction.The original designations of the disorder stem from the morphological resemblance of the foamy cells to lipid-laden histiocytes. However, subsequent investigations have shown these cells to contain myofibrils interposed with Z lines. It has, therefore, been suspected that the leading cell population might be related to the myocardium.Using a histochemical method for the demonstration of cholinesterase activity in the foamy cells, we present evidence that histiocytoid cardiomyopathy may in fact correspond to a maldevelopment of the Purkinje cell system of the heart.     

Expression profile of PRAF2 in the human brain and enrichment in synaptic vesicles

PRA1 domain family, member 2 (PRAF2) is a novel 19-kDa protein with a prenylated Rab acceptor 1 (PRA1) motif and four transmembrane domains. Our previous studies revealed that PRAF2 is highly expressed in the brain and serves as a candidate prognostic marker in neuroblastoma (NB). PRAF2 is related to proteins PRAF1 (PRA1, prenylin, Yip3) and PRAF3 (GTRAP3-18, JWA, Arl6-IP5), both of which are enriched in the brain and implicated in cellular transport and endo/exocytic vesicle trafficking. However, the function for PRAF2 remains unknown. In this study, we analyzed the distribution and localization of PRAF2 in the mature human brain using two new antibodies specific for the protein. Analysis by immunohistochemistry revealed that in the human cerebellum, the PRAF2 protein was strongly expressed in Purkinje cells and, more moderately, in cells of the molecular and the granular layers. In the cerebral cortex, hippocampus, and lateral ventricles, PRAF2 protein was detected in neuronal cells, but not in non-neuronal cells. Intriguingly, immunoblot analysis revealed that PRAF2 is enriched in synaptic vesicles (SVs) prepared from rat brains. The expression of PRAF2 in specific regions of the brain including SVs suggest an important physiological function for this novel protein, possibly by participating in multiple aspects of SV maturation, transport, and signal transmission.