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Biomedical subjects

D Miceli

Publications and source records attributed to D Miceli.

At least 19 recordsLinked to original sources
PubMed1995

Sex steroids up-regulate E-cadherin expression in hormone-responsive LNCaP human prostate cancer cells.

There is convincing evidence that a reduced expression of the E-cadherin cell-cell adhesion molecule associates with low tumor grade and poor prognosis in prostate cancer patients. However, little is known on how E-cadherin levels are regulated in human prostate cancer cells. We have inspected the effect of both androgens and estrogen on the expression of E-cadherin in the hormone-responsive LNCaP prostate tumor cell line, which is endowed with both androgen and estrogen receptors. Using both Dot Blot analysis and immunocytochemistry we have observed that either steroid significantly increased E-cadherin levels in these cells; this effect was not reversed by the simultaneous addition of the relevant antagonist, hydroxyflutamide or ICI-182,780.

Androgen Antagonists↗
PubMed1995

Distribution of GABA immunoreactivity in the retino-recipient layer of the viper optic tectum. A light and electron microscope quantitative study.

The distribution of GABA-immunoreactivity was investigated in the principal retino-recipient layer of the optic tectum in the snake Vipera aspis. This layer, the stratum griseum et fibrosum superficiale, contained an important proportion (approximately 50%) of small GABA-immunoreactive interneurons, characterized by a voluminous invaginated nucleus surrounded by a thin rim of cytoplasm poor in organelles and occasionally showing pleiomorphic synaptic vesicles, which could also be observed in some of the dendrites that contained synaptic vesicles. In the neuropile, the GABA-immunoreactive profiles containing synaptic vesicles could be subdivided into dendrites containing synaptic vesicles and axon terminals with pleiomorphic synaptic vesicles. The dendrites containing synaptic vesicles (23.4% of all profiles containing synaptic vesicles) were postsynaptic either to optic terminals (39.2%), GABA-immunoreactive axon terminals with pleiomorphic synaptic vesicles (48.2%) or to immunonegative (S1) boutons with round synaptic vesicles (12.6%). These dendrites were presynaptic to GABA-immunoreactive (18%) neurons or immunonegative (82%) neurons. The axon terminals with pleiomorphic synaptic vesicles, which represented 47.4% of all profiles, were predominantly (99%) GABA-immunoreactive and four types could be distinguished according to cytological criteria. These axon terminals made synaptic contacts for the most part (78%) with immunonegative profiles, and more rarely (22%) with immunoreactive neurons. These data are compared to those previously obtained in the homologous structure of other vertebrate species, birds and mammals in particular.

Animals↗
PubMed1995

Ipsilateral visual projections in non-eutherian species: random variation in the central nervous system?

The published descriptions of ipsilateral visual pathways in non-eutherian species are reviewed. Such pathways exist in members of all vertebrate classes; since they exist in agnathans, it is suggested that the presence of ipsilateral visual projections is the ancestral condition. None of the published attempts to explain the considerable interspecific variation of these pathways can be generalised to all vertebrate species: in particular, this variation is not generally related to the degree of overlap of the visual fields, to a particular mode of life, nor to taxonomic position within a given vertebrate category and cannot consistently be explained by variation at the albino locus. It is suggested that this variation is the result of purely random variation of unidentified elements of the genetic material or of epigenetic mechanisms and hence that ipsilateral visual projections are functionally neutral. This conclusion is supported by some extremely fragmentary behavioral data indicating that the information they provide is redundant.

Animals↗
PubMed1993

Retrograde transneuronal transport of the fluorescent dye rhodamine beta-isothiocyanate from the primary and centrifugal visual systems in the pigeon.

The transneuronal labeling properties of the fluorescent dye Rhodamine beta-isothiocyanate (RITC) were investigated in the pigeon following the intraocular injection of the tracer either alone or in combination with kainic acid (RITC/KA). The RITC was transported bidirectionally from the eye producing both orthograde axonal and terminal labeling of the primary visual system (PVS) and retrograde labeling of the centrifugal visual system (CVS) comprising the n. isthmo-opticus (NIO) and associated ectopic neurons (EN) as well as the tractus isthmo-opticus (TIO). In addition, RITC-positive cell bodies were identified in layers 9/10 of the optic tectum, n. isthmi parvocellularis (Ipc) and the hyperstriatum accessorium (HA) subdivision of the telencephalic visual Wulst. In the RITC/KA experiments, the orthograde transport of the dye within the PVS was selectively suppressed and this coincided with the absence of somatic labeling in n. Ipc and HA. The results are explained in terms of transneuronal transport of RITC, involving the terminal uptake and subsequent retrograde axonal transport of the tracer within second-order neurons in n. Ipc and HA which project to the PVS and in tectal layers 9/10 projecting to the CVS. Moreover, the transneuronal transport of RITC, as demonstrated using the present experimental conditions, appears to be very specific and only labeled distant cell populations known to project to either the PVS or CVS.

Animals↗
PubMed1992

Evidence of GABA-immunopositive neurons in the dorsal part of the lateral geniculate nucleus of reptiles: morphological correlates with interneurons.

The distribution and staining pattern of gamma-aminobutyric acid immunoreactivity have been examined by both light and electron microscopy in the dorsal part of the lateral geniculate nucleus of three reptilian species: the turtle Chinemys reevesi, the lizard Ophisaurus apodus and the snake Vipera aspis. After perfusion of the animals with 1% paraformaldehyde and 1% glutaraldehyde and polyethyleneglycol embedding of the brains, the analysis of sections processed immunocytochemically with an anti-GABA antiserum has revealed a moderate-to-dense labeling of the neurons of the dorsal part of the lateral geniculate complex in these species. Labeled cell bodies are small-sized, either rounded or fusiform and the GABA-positive dendrites emerging from them are not preferentially oriented in any particular direction. Quantitative studies in Vipera indicate that GABA-positive neurons make up about 14% of the population of neurons of the dorsal part of the lateral geniculate nucleus. Electron microscopy of specimens treated by either pre- or post-embedding techniques has confirmed that these cells corresponded to neurons. No glial cells were ever observed to be immunopositive. These GABA-positive neurons, characterized by the presence of pleiomorphic synaptic vesicles localized either in their perikaryon or more often in presynaptic dendrites, established symmetrical synaptic contacts. In this case, the latter were involved both pre- and postsynaptically in serial and, more rarely, in triadic arrangements, a synaptic organization specific to interneurons. The involvement of such GABA-positive neurons in local circuits is discussed.

Animals↗
PubMed1991

Divergence and collateral axon branching in subsystems of visual cortical projections from the cat lateral posterior nucleus.

The projections from the lateral (LPl), intermediate (LPi) and medial (LPm) subdivisions of the cat lateral posterior nucleus (n. LP) to visual areas 17, the posteomedial (PMLS) and posterolateral (PLLS) lateral suprasylvian and anterior ectosylvian (AEV) were studied using the retrograde labeling technique following concomitant injections of fluorescent dyes (Fast blue, Nuclear yellow, Evans blue and Rhodamine beta-isothiocyanate) into the different cortical loci. The results showed a medial-lateral topographical reversal of the visual n. LP-cortical connections: The ventral portion of LPl projects to area 17 whereas more dorsolateral regions of LPl and lateral LPi provide input to PMLS. Cells in medial LPi project mainly to the PLLS cortex and AEV receives afferents from the LPm. Areas of overlap were identified within the ventral LPl which projects to both area 17 and PMLS and within the LPi/LPm border region at the origin of connections to both PLLS and AEV. Furthermore, some single neurons within the areas of overlap were found to be double-labeled indicating divergent projections to their respective cortical targets via collateral axon branching. The data show that divergence and axonal branching are common features of the different n.LP-visual cortical subsystems and support the notion of the existence of families of thalamo-cortical systems which are distinct in their connection patterns and underlying functional properties.

Animals↗
PubMed1990

Reorganization of GABAergic synapses in the viper optic tectum following retinal deafferentation.

The immunocytochemical analysis of the viper optic tectum was carried out with an anti-gamma-aminobutyric acid (anti-GABA) antiserum following retinal deafferentation for survival times ranging from 10 to 90 days. The ultrastructure of the SGFS neuropil revealed that among the two types of axon terminals, namely pleiomorphic (P) and spherical (S) boutons, a subtype of the latter (S2), corresponding to the retinal terminals, was found to degenerate at varying rates. In most cases, this resulted in the glial engulfment of the presynaptic partner, leaving the postsynaptic differentiation free (FPSD). Beyond the two first months, the asymmetrical freed postsynaptic differentiations (FPSDs) were progressively and partly reafferented by GABA-positive P axon terminals through a sliding process. Three months postoperative, the number of GABA-positive P axon terminals which, in normal animals, establish asymmetrical contacts (1-2%), was found to increase to approximately 10%. The postsynaptic differentiation may represent a mismatched receptor area for the new competing presynaptic partners. The functional implications of such 'axonal terminal sprouting' are discussed.

Afferent Pathways↗
PubMed1990

Projections of the dorsolateral anterior complex and adjacent thalamic nuclei upon the visual Wulst in the pigeon.

The distinctive patterns of thalamic input to the rostral (R), intermediate (I) and caudal (C) divisions of the pigeon Wulst were determined using the retrograde multiple label technique following concomitant injections of various fluorescent tracers into different Wulst loci. The results showed topographical projections from components of the visual thalamic n. dorsolateralis anterior complex. Major ipsilateral and contralateral projections upon the R and I Wulst stem from the pars lateralis ventralis and dorsalis nuclei, respectively. The nuclei pars lateralis rostralis, pars magnocellularis and n. suprarotundus provide weak bilateral projections to all of the Wulst divisions sampled. Lastly, bilateral connections from the n. superficialis parvocellularis upon I and C, and from n. dorsolateralis posterior upon the posterior C Wulst were also demonstrated. Based upon their patterns of terminal distribution upon the Wulst, some of these thalamic nuclei are compared to specific components of the mammalian geniculate and extrageniculate visual systems.

Animals↗
PubMed1990

A quantitative study of cerebrovascular variation in inbred mice.

The arteries of the base of the mouse brain were examined after perfusion with India ink. A qualitative difference exists between inbred mice of three strains (C57BL/6J, 129/J and BALB/cCF) on the one hand, and genetically defined heterogeneous mice on the other; the latter consistently show anomalies similar to those previously described in genetically undefined rodents, whereas inbred mice do not. A quantitative morphometric analysis of the Circle of Willis of inbred mice was undertaken. The results of this analysis are consistent with the notion that the differences in shape between the circles of Willis of different strains of inbred mice are due to additive genetic variation between these strains.

Animals↗
PubMed1990

[Immunohistochemical analysis of the serotonin system in the brain of lizard Ophisaurus apodus].

The distribution of serotoninergic neurons (localization of somata, principal fiber tracts and projection zones) was investigated in the brain of the lizard Ophisaurus apodus using a specific antibody directed against serotonin (5-HT). A comparison of the results with those of the literature revealed that in spite of minor variations in the distribution of 5-HT in the different reptiles examined there exist common features which correspond to a general organizational pattern.

Animals↗
PubMed1990

Regeneration of the retinotectal system in a flatfish, Scophthalmus maximus L.

Regenerating retinotectal fibres were visualized by radioautography in turbots (Scophthalmus maximus L.) maintained at 10 degrees-14 degrees C either after crushing one optic nerve or after crushing one nerve and removing the contralateral eye. Regeneration was found to be more extensive 2 days after crushing the right optic nerve than after crushing the left and was further enhanced by contralateral enucleation. The difference between experimental groups was markedly less pronounced by 113 days postoperatively and by 293 days the specimens resembled normal material. Between 113 and 222 days, a transient projection to the ipsilateral tectum was found, which disappeared by 293 days whether or not the contralateral eye had been removed. The differences between the present results and previous findings in symmetrical Cyprinid fish are discussed.

Animals↗
PubMed1989

Centrifugal innervation of the lamprey retina. Light- and electron microscopic and electrophysiological investigations.

Centrifugal fibers and their synaptic connections were studied in retinas of the lamprey Lampetra fluviatilis. The morphological analysis of retinofugal and retinopetal elements was performed after their horseradish peroxidase (HRP) filling through either the cut optic nerve in isolated retina preparations or after intracerebral HRP injections. In flat-mounted retinas, labeled ganglion cell bodies with their dendritic arborizations as well as centrifugal axons were found. The topography of labeled ganglion cell bodies and fibers in semi-thin plastic sections is described. The electron microscopic analysis revealed that the centrifugal terminals synapse either upon unlabeled somata or profiles containing synaptic vesicles (PCSVs). In more rare cases these boutons seem to establish synaptic contacts on ganglion cell dendrites. The target cell bodies were located within the inner part of the inner nuclear layer, whereas postsynaptic dendrites and PCSVs were mainly observed in the outer portion of the internal synaptic layer. Stimulation of the optic nerve in isolated retinas produced antidromic responses in 23 neurons and in 9 of these cells, an antidromic spike was followed by a postsynaptic potential (PSP). Ten cells yielded no antidromic response, but showed PSPs sometimes associated with spikes. The morphological and physiological evidence obtained indicate that these PSP-generating cells were activated synaptically by centrifugal fibers and that in the lamprey retina, these fibers make contacts either with dendrites or somata of amacrine cells and probably with ganglion cell dendrites.

Animals↗
PubMed1988

Visual system degeneration in the glaucomatous albino quail.

The peripheral (eye, retina, optic nerve) and central (primary optic tracti and centers, centrifugal visual tractus and nucleus) visual system of an imperfect albino quail mutant with a sex linked recessive gene was examined in 32 specimens ages 1 week - 16 months-hatch using various histological techniques. During the first weeks the visual system was normal and comparable in its overall organization to that found in the pigmented quail. However, the ipsilateral retinal projections were observed to be weaker in the young mutant, then completely disappeared two months after birth. Initial signs of the bupthalmos, a form of spontaneous glaucoma, appeared between the 3rd and 5th months. This was characterized by a distention of the eye linked to an increase in intraocular pressure. The pathological process was progressive and at 16 months the eye was very prominent, the anterior chamber deep and a large and globular cornea was noted. The glaucoma progressively induced different histopathological changes in the visual system including: cupping of the optic disc, degeneration of optic axons and their parent ganglion and centrifugal cells and cavernous degeneration. All of these phenomena were identifiable at about the 10th post-natal month and progressed in a relatively constant and orderly manner. The retinal projections to the nucleus ectomamillaris, ventral and lateral optic tectum and ventral pretectum were the first to degenerate. The degeneration of optic fibers attaining the dorsal pretectum and dorsal thalamus occurred later. Furthermore the retrograde degeneration in the centrifugal isthmo-optic nucleus progressed from the external to the internal pole. The mechanisms involved in the selective degeneration of centrifugal and centripetal optic fibers is discussed.

Age Factors↗
PubMed1987

Nuclear origin of the centrifugal visual pathway in birds of prey.

The isthmo-optic nucleus (NIO) at the origin of the retinopetal pathway was examined in 12 birds of prey (strigiforms and falconiforms) using cytoarchitectonic methods and after the intraocular injection of the regrograde tracers Rhodamine beta-isothiocyanate and Fast blue. The NIO was found to be poorly differentiated and reticular in appearance and depending on the species contained between 900 and 1400 neurons. These values are approximately 10 times less than those recorded in the pigeon and chicken. As in the latter species, the experimental data obtained in the strigiform Tyto alba showed the presence of retinopetal ectopic neurons bilaterally. However the ipsilateral contingent was proportionally larger in the nocturnal raptor. The functional significance of the poorly developed centrifugal visual system in birds of prey is discussed.

Animals↗
PubMed1987

Time course of degeneration of the visual system induced by spontaneous glaucoma in the albino quail (Coturnix coturnix japonica).

The retinal projection of an imperfect albino quail mutant with a sex-linked recessive gene was examined 2 weeks-16 months post-hatch using various histological methods. During the first weeks the visual system was normal. Initial signs of buphthalmos, a form of spontaneous glaucoma, appeared between the 3d and 5th months. Its development induced a degeneration of the retinal projections according to a relatively precise sequence progressing from the mesencephalic tegmentum to the optic tectum, then from the pretectum to the thalamus. The data suggest that the degeneration of the optic axons results from their mechanical compression due to the increased intraocular pressure.

Age Factors↗
PubMed1987

The primary optic system in a microphthalmic snake (Calabaria reinhardti).

The retinal projections in the microphthalmic snake Calabaria reinhardti were investigated by means of the radioautographic method following intraocular injections of [3H]proline. The results demonstrated the existence of a general pattern of organization of the primary visual system comparable to that observed in macrophthalmic snakes. However, most of the primary optic centers appeared reduced and showed varying signs of atrophy, whereas others were completely absent. Elsewhere, the ipsilateral visual component appeared as well developed as that found in macrophthalmic snakes. The evolutionary significance of the differential microphthalmic pattern of organization of the primary visual system is discussed.

Animals↗