Biomedical subjects

D Miceli

Publications and source records attributed to D Miceli.

97 records · Page 6Linked to original sources

PubMedDate not supplied

Sequential events of degeneration and synaptic remodelling in the viper optic tectum following retinal ablation. A degeneration, radioautographic and immunocytochemical study.

The ultrastructural changes taking place in the retino-recipient layers of the viper optic tectum were examined between 5 and 122 days after retinal ablation. The initial degeneration of retinotectal terminals proceeds at widely different rates and is characterized by a marked degree of polymorphism in which a number of different patterns can be discerned. In the final stages of degeneration, either both the degenerating bouton and the distal portion of the postsynaptic element are engulfed by reactive glia, or, more frequently, only the degenerating terminal is eliminated and the postsynaptic differentiation remains. The free postsynaptic differentiations are reoccupied predominantly by boutons containing pleiomorphic vesicles and which are for the most part gamma-aminobutyric acid (GABA)ergic, thus forming heterologous synapses; less frequently these sites are occupied by boutons of the ipsilateral visual contingent to form homologous synapses. These two processes, both of which depend on terminal axonal sprouting, take place within the first 3 postoperative months. They are followed by a decrease in the number of heterologous synapses and a concurrent increase in the number of homologous synapses newly formed by optic boutons generated by collateral preterminal sprouting of ipsilateral retinotectal fibres. The data suggest that partial deafferentation of the optic tectum induces a transitory GABAergic innervation of free postsynaptic sites prior to the restoration of new retinal synaptic contacts.

Afferent Pathways↗

PubMedDate not supplied

The serotoninergic system of the brain of the lamprey, Lampetra fluviatilis: an evolutionary perspective.

The distribution of serotonin(5HT)-immunoreactive cell bodies, nerve fibers and terminals was investigated by light microscopy in the lamprey Lampetra fluviatilis. Twenty-three distinct groups of 5HT neuronal somata were identified from diencephalic to rhombencephalic levels in the brain. The diencephalon contained a subependymal population of immunoreactive cells in contact with the cerebrospinal fluid (CSF), which could be subdivided into five separate groups situated in the hypothalamus and ventral thalamus; five additional groups of immunoreactive diencephalic neurons, situated in the dorsal thalamus and thalamo-pretectum, which were not in contact with the CSF, were also identified. In the midbrain, in addition to a few labelled neurons in the optic tectum, two structures containing immunoreactive cells were identified in the tegmentum mesencephali. None of these 5HT cells corresponded to the retinopetal neurons which are situated in the same region. A very large number of 5HT neurons were observed in the hindbrain which could be divided into seven groups in the isthmus rhombencephali and a further three in the rhombencephalon proper. Immunoreactive fibers and terminals were widely distributed throughout the neuraxis. In the telencephalon two 5HT fibers assemblies, lateral and medial, could be identified which terminated in both pallial and subpallial structures. The richest serotoninergic innervation in the telencephalon was found in the lateral portion of the primordium hippocampi and the medial part of the corpus striatum. In the diencephalon, the distribution of immunoreactive fibers and terminals was heterogeneous, being most pronounced in the lateral hypothalamic area and in the infundibulum. The densest arborization of fibers in the mesencephalon was found in the stratum fibrosum et cellulare externum of the optic tectum, a major site of retinal projection, and in the nucleus interpeduncularis mesencephali as well as in the oculomotor nuclei. The rhombencephalon is richly endowed with serotoninergic fibers and terminals, many labelled arborizations being found in the nuclei isthmi rhombencephali and around the nucleus motorius nervi trigemini. Comparative analysis of the serotoninergic systems of petromyzontiforms and gnathostomes indicates that the evolution of this system involves a progressive elimination of the rostral immunoreactive cells and an increasing complexity of the caudal population of serotoninergic neurons.

Animals↗

PubMedDate not supplied

GABA immunoreactivity in the nucleus isthmo-opticus of the centrifugal visual system in the pigeon: a light and electron microscopic study.

The present study examined GABA immunoreactivity within the retinopetal nucleus isthmo-opticus (NIO) of the pigeon centrifugal visual system (CVS) using light- (immunohistofluorescence, peroxidase anti-peroxidase: PAP) and electron- (postembedding GABA immunogold) microscopic techniques. In some double-labeling experiments, the retrograde transport of the fluorescent dye rhodamine beta-isothiocyanate (RITC) after its intraocular injection was combined with GABA immunohistofluorescence. GABA-immunoreactive (-ir) somata were demonstrated within the neuropilar zone of the NIO adjacent to the centrifugal cell laminae whereas the centrifugal neurons were always immunonegative. A quantitative ultrastructural analysis was performed which distinguished five categories of axon terminal profiles (P1-5) on the basis of various cytological criteria: type of synaptic contact (symmetrical or asymmetrical); shape, size, and density of synaptic vesicles as well as the immunolabeling (positive or negative), size of profile and appearance of hyaloplasm. Numerous GABA-ir afferents to centrifugal neurons via axon terminal types P2a, P2c, and P3 were observed which comprised 47.1% of the total input. Moreover, the data suggest that some of the P2a terminals, which make up 26.4% of the input, stem from the intrinsic GABA-ir interneurons, whereas the latter receive P1, P3, but also P2 terminal input, indicating that interneurons may contact other interneurons via type P2a axon terminals. The results also suggest that the GABA-ir P3 or the immunonegative P1b and P5 axon terminals are of extrinsic origin arising from cells in the optic tectum whereas the P2c and P4 axon terminals are associated with extra-tectal input to the NIO. The GABAergic innervation of centrifugal neurons within the NIO may be the basis for the demonstrated facilitatory effect of the centrifugal output upon ganglion cell responses. This is relevant to hypotheses regarding CVS involvement in attentional mechanisms through selective enhancement of retinal sensitivity depending on the location of meaningful or novel stimuli.

Animals↗

PubMedDate not supplied

Brain-stem afferents upon retinal projecting isthmo-optic and ectopic neurons of the pigeon centrifugal visual system demonstrated by retrograde transneuronal transport of rhodamine beta-isothiocyanate.

Brain-stem afferents to the n. isthmo-opticus (NIO) and ectopic neurons (EN) of the centrifugal visual system (CVS) were determined in the pigeon using the retrograde transneuronal transport of the fluorescent dye Rhodamine beta-isothiocyanate (RITC) after its intraocular injection. In other experiments, either RITC was injected into various periocular tissues (controls) or the retrograde tracer Fluoro-gold (FG) was injected stereotaxically in the NIO. Following intraocular injections, the RITC retrograde labeling of cell bodies was observed contralaterally in the NIO and EN and transneuronally in layers 9/10 of the optic tectum, area ventralis-Tsai, zona peri-NIII, mesencephalic and pontine reticular formation (PRF), n. linearis caudalis-raphe, and bilaterally within a region referred to as zona peri-n.NVI (Zp-n.NVI) immediately underlying the abducens nerve nucleus. None of the above structures were labeled after RITC periocular injections. The FG labeling revealed that the tectal efferent neurons were mainly medium-sized, multipolar cells whose dendrites extended superficially to retino-recipient tectal layers 6 and 5. Quantitative measurements of the distribution of layers 9/10 RITC-labeled neurons indicated the highest densities to be localized within the ventral tectum corresponding to the representation of the dorsal retina and inferior visual field. We suggest that visual and nonvisual brain-stem afferents upon NIO and EN may play a role in the proposed mechanism of the avian CVS in attention, ground-feeding behavior, and modulation of retinal sensitivity.

Animals↗

PubMedDate not supplied

Transverse fracture of the second sacral vertebra: description of a clinical case.

The authors report a rare case of transverse fracture of the second sacral vertebra that was isolated, with neurologic deficit, and treated conservatively by reduction opposing the trauma mechanism, and immobilization in plaster. After 22 months there was good neurologic recovery, although some perineal sensory disorders persisted, as did sexual deficit. This method is believed to be a valid one as an alternative to surgery, which is difficult, and not without complications.

Accidents, Occupational↗

PubMedDate not supplied

Membrane vesicles in ovarian cancer fluids: a new potential marker.

The rate of membrane vesicle shedding by tumor cells is probably related to their invasive capability. In order to verify whether the vesicle amount could be utilized as a marker of different pathologies, we analyzed biological fluids obtained from 33 patients with gynecological diseases. In fluids of benign serous cysts, vesicle content was extremely low; in cystoadenomas and fibromas generally it was low. On the contrary, large amounts of vesicles were found in malignant tumor fluids. Gelatin zymographies showed the presence of MMP-2 and MMP-9 in all vesicles except in those recovered from fluids of some serous cysts. A positive correlation between tumor malignancy and both vesicle-amount and vesicle-associated MMP-2 activity was noticed. We also analyzed vesicle content in ascitic fluids recovered from two carcinomas at different times during clinical treatment. In both cases, tumor progression, not monitored by Ca 125 levels, was pointed out by an increased amount of vesicles in ascites. These findings suggest that vesicle content in biological fluids could represent a new useful marker of tumor aggressiveness and tumor progression.

Ascitic Fluid↗

PubMedDate not supplied

Snapping hip: etiopathogenesis and surgical treatment.

Snapping hip is a polymorphous pathology the genesis of which is multifactorial, characterized by a snapping sensation which may be painful, and occurring during movement of the hip or during walking. Clinical and instrumental diagnosis for an accurate etiopathogenetic classification is essential to correct surgical treatment, that must be reserved only for cases with painful symptoms and with disorders in walking. The authors provide a classification system of the syndrome, describing four different varieties of the pathology and relative surgical treatment.

Adolescent↗