PubMed Health⌕ Search

Biomedical subjects

M R Celio

Publications and source records attributed to M R Celio.

At least 55 records · Page 3Linked to original sources
PubMed1996

Preservation of calretinin-immunoreactive neurons in the hippocampus of epilepsy patients with Ammon's horn sclerosis.

Selective neuronal vulnerability and aberrant axonal reorganization in the hippocampus may play an important role for the pathogenesis of pharmaco-resistant temporal lobe epilepsy (TLE). Interneurons containing calcium-binding proteins (CaBPs) are candidates for pathogenetically relevant neurons in the hippocampus of patients with TLE. Here we have examined the cellular localization and distribution of calretinin (CR), a recently discovered CaBP, in the hippocampus of 35 patients with TLE. There was a striking preservation of CR-immunoreactive neurons in TLE patients with Ammon's horn sclerosis (AHS). No significant differences in the distribution of CR-immunoreactive neurons were observed between patients with lesion-associated TLE and control patients without epilepsy. However, a subpopulation of CR-immunoreactive interneurons with morphological features of Cajal-Retzius-like cells, which are only transiently detectable in the normally developing hippocampus, was markedly increased in epilepsy patients with AHS. This increase did not correlate with the duration of the epileptic disorder. Another significant finding was a striking increase and reorganization of CR-immunoreactive neuropil throughout the entire molecular layer of the dentate gyrus (DG-ML) in patients with AHS as compared to patients with focal lesions and control specimens. Ultrastructural analysis identified the CR-immunoreactive axonal profiles as components of an inhibitory, intrinsic neuronal system. The presence of a CR-positive, aberrant cell population, in combination with sprouting of CR-positive axonal processes may significantly alter the gating function of the dentate gyrus and thereby increase hippocampal epileptogenicity in epilepsy patients with AHS.

Adolescent↗
PubMed1995

Calretinin-positive Cajal-Retzius cells persist in the adult human neocortex.

The occurrence of Cajal-Retzius (CjRe) cells was studied in four cortical areas of five normal adult humans using antibodies against calretinin. Calretinin immunofluorescence and autofluorescence of lipofusin granules in CjRe cells were visualized by dual channel confocal laser scanning microscopy. Three types of CjRe cells existed in the adult human cortex: horizontal, triangular and multipolar, and their number did not decrease with ageing. Horizontal CjRe cells were found in all cortical areas; they contained no lipofusin or less than other cells. Triangular CjRe cells with descending dendrites were less numerous. Multipolar CjRe cells were rare and contained more lipofuscin. We conclude that calretinin-immunoreactivity can be used to study CjRe cell morphology in normal and diseased adult human brain.

Adult↗
PubMed1995

Alternative splicing of calretinin mRNA leads to different forms of calretinin.

cDNA clones for calretinin, a member of the troponin-C family of calcium-binding proteins, were isolated from a cDNA library of the human colon carcinoma cell line WiDr. Sequence analysis revealed two forms of alternatively spliced calretinin mRNAs encoding C-terminally truncated proteins. Exon 7 was either spliced to exon 9 (delta 8) or to exon 10 (delta 8,9); both resulted in a frame shift and a translational stop at the second codon of exon 9 (delta 8), or at codon 15 of exon 10 (delta 8,9), respectively. The presence of delta 8 and delta 8,9 calretinin mRNA in WiDr cells was confirmed using reverse-transcriptase PCR and sequence analysis of the amplicon, as well as by a ribonuclease protection assay. Co115/3 and three other human colon carcinoma cell lines were found, by reverse-transcriptase PCR to also contain delta 8,9 calretinin mRNA. The truncated proteins were able to bind calcium, as evidenced by a calcium blot of the delta 8 form (calretinin-20k) and delta 8,9 form (calretinin-22k) expressed in Escherichia coli. Immunohistochemical staining using an antiserum specific for the novel C-terminus of calretinin-22k confirmed its presence in WiDr, Co115/3 and three additional colon carcinoma cell lines. The fact that alternative splicing of calretinin was found in five different cell lines suggests that alternatively spliced calretinins fulfill a physiological function.

Alternative Splicing↗
PubMed1995

Production and analysis of transgenic mice with ectopic expression of parvalbumin.

Transgenic mice expressing rat parvalbumin under the control of the human metallothionein IIA (MTII A), SV-40 early, and neuron-specific enolase (NSE) promoters were produced. Ectopic expression was analyzed by RNA polymerase chain reaction and RNase protection in combination with immunohistochemistry. From a total of 25 transgenic lines 18 were found to express the transgene. Expression strength and tissue specificity were dependent upon the promoter used and varied considerably among animal lines produced with the same construct. Highest constitutive MT IIA-driven expression was found in lung, liver, heart, and kidney, as well as in brain, and lower amounts of transgene expression were found in spleen, testis, and muscle. Immunohistochemistry of tissue sections of metallothionein-parvalbumin transgenic strain 29 in the non-induced state revealed that ectopic PV mRNA is translated into protein. Short-term induction of the MT IIA promoter by CdSO4 or CdCl2 leads to a shift in tissue specificity and does not increase ectopic expression in tissues where the transgene is active in the noninduced state. As expected the NSE promoter showed highest activity in brain. However, NSE-driven expression could also be detected to various degrees in all investigated tissues. SV-40-dependent PV expression showed no tissue preference and varied considerably among different strains. Except for the observation that the SV-40-PV construct showed lower yields in transgenic production and reduced numbers of positive offspring no obvious impairment of growth or behavior as a consequence of transgenic PV expression could be detected.

Animals↗
PubMed1995

Relationship between astrocytic processes and "perineuronal nets" in rat neocortex.

"Perineuronal nets" (PNs) ensheath a subtype of inhibitory neurons in the mammalian neocortex. In the light of the proposal that PNs consist of glial processes, we have analyzed the relationship between intracellularly injected glial cells and PNs in the rat neocortex. Glial cells were injected iontophoretically with Lucifer Yellow in lightly fixed tissue slices and PNs were visualized with the lectin from Vicia villosa. Using confocal laser scanning microscopy, glial processes and PNs were identified as distinct structures. Lectin labeling was consistently associated with the extracellular space interposed between LY-labeling was consistently associated with the extracellular space interposed between LY-labeled astrocyte processes and neurons. Of the different types of glial cells injected, only the densely-ramifying protoplasmic astrocytes extended processes which could be traced to contact PNs. These protoplasmic astrocytes also sent out processes to adjacent neurons not ensheathed by PNs, and to capillaries. The present data strongly suggests that PNs do not consist of glial processes but rather support the idea that PNs represent specialized extracellular material interposed between the surface of some inhibitory interneurons and astrocytic processes.

Animals↗
PubMed1995

Changes in shape and motility of cells transfected with parvalbumin cDNA.

Parvalbumin is thought to act as a Ca2+ buffer in skeletal muscle fibers, but its physiological role in brain, kidney, and testis remains unclear. We have transfected parvalbumin cDNA into a human ovarian adenocarcinoma cell line, which normally does not express this protein. The induced expression of parvalbumin under the control of three different promoters causes: (1) changes in the morphology of the cells from epitheloid to fusiform, (2) an increase in motility of whole cell clusters, and (3) a decrease in the mitotic rate. Transfection with a mutated cDNA of rat parvalbumin incapable of binding Ca2+ had no effect on these three parameters. Our results indicate that ectopic expression of parvalbumin influences not only cell division [Rasmussen and Means (1989) Mol. Endocrinol. 3, 588-596], but also cell shape and motility by modulating intracellular Ca2+ handling. This may be a basic function of parvalbumin when it is intrinsically expressed in differentiated nonmuscle cells.

Cell Line, Transformed↗
PubMed1994

Localization of calretinin in cells of layer I (Cajal-Retzius cells) of the developing cortex of the rat.

In order to be able to study the still disputed fate and function of the large Cajal-Retzius cells in the marginal zone (prospective layer I) during corticogenesis, it is necessary to have an unambiguous marker for them. We have found that antibodies to the calcium-binding protein calretinin label Cajal-Retzius cells in the rat throughout the whole period of corticogenesis into adulthood. Calretinin positive cells were also detected in the subplate, cortical plate and the ventricular zone. Transient expression of calretinin was observed in cells of the infragranular layers of the developing cortex. We conclude that calretinin can be used as a marker protein for Cajal-Retzius cells.

Aging↗
PubMed1994

Perineuronal nets--a specialized form of extracellular matrix in the adult nervous system.

One century ago, Camillo Golgi described 'perineuronal nets' enwrapping the cell bodies and proximal dendrites of certain neurons in the adult mammalian central nervous system and suggested that they represent a supportive and protective scaffolding. Although other neuroanatomists validated the existence of these nets on selected neurons in the adult brain, there was a lack of agreement on their origins, composition and function. The application of modern molecular and ultrastructural methods has brought new insights and a renewed interest in these classic observations. Recent data suggest that perineuronal nets result from the visualization of extracellular matrix molecules that are confined to the space interposed between glial processes and the nerve cells that they outline. The material confined to these spaces can be visualized selectively by antibodies directed to glycoproteins (e.g., tenascin and restrictin/janusin), proteoglycans (e.g., chondroitin sulfates), markers for hyaluronan as well as by lectins recognizing N-acetylgalactosamine and by monoclonal antibodies directed to epitopes on unknown molecules (e.g., HNK-1, VC1.1 and Cat 301). This review examines the emerging clarification of classical observations of perineuronal nets and the functional implications suggested by their molecular composition. Also discussed are studies that further extend observations on the time of development and of the specificity in the occurrence of perineuronal nets. In the adult brain the molecules constituting the 'perineuronal nets of matrix' could serve as recognition molecules between certain neurons and their surrounding cells and participate in the selection and consolidation of their relationship.

Animals↗
PubMed1993

In vitro detection of calretinin immunoreactivity in chicken embryo dorsal root ganglion neurons: a possible developmental marker.

Calretinin, a cytosolic calcium-binding protein, is widely expressed in mammalian and chicken neurons, including subpopulations of dorsal root ganglion neurons. In chicken embryo spinal ganglion cells, calretinin first appears on the 9th day of incubation. To determine whether the expression of this protein is maintained in vitro and depends on the developmental stage, dissociated dorsal root ganglion cultures from chick embryos at E6 and E10 (before or after establishing connections) were processed for calretinin immunohistochemistry. Cultured neurons from E6 embryos never showed calretinin immunoreactivity at any culture duration, whereas neurons from E10 embryos displayed strong immunostaining immediately after attaching to the culture dish. Quantitative evaluation revealed that the percentage of calretinin-positive neurons increased until day 3 in culture and afterwards declined in parallel the total cell number. These results indicate that primary sensory neurons express calretinin in vitro similarly as in vivo and the gene expression depends from the establishment of connections with peripheral targets.

Animals↗
PubMed1993

'Perineuronal nets' around cortical interneurons expressing parvalbumin are rich in tenascin.

'Perineuronal nets' are ill-known structures enwrapping the cell bodies and proximal dendrites of certain neurons in the brain. It is as yet unclear if they represent a cytological entity or extracellular material. Using immunohistochemical methods we have detected the presence of the extracellular matrix-protein, tenascin, in the 'perineuronal nets' surrounding certain cortical interneurons. We have also shown that tenascin antibodies label the circumference of parvalbumin-immunoreactive neurons preferentially. We conclude that this classical matrix protein is a major component of 'perineuronal nets'. Therefore, 'perineuronal nets' may represent sites of privileged adhesion between nerve and glial cells.

Animals↗
PubMed1993

Calretinin-immunoreactive neocortical interneurons are unaffected in Alzheimer's disease.

Recent studies have revealed that select neuronal populations may display a differential sensitivity to degeneration in Alzheimer's disease. For example, large pyramidal neurons have been shown to be vulnerable, whereas small, local circuit neurons appear to be resistant to the pathologic process. More significantly, interneurons that contain the calcium-binding proteins parvalbumin and calbindin are particularly resistant to degeneration in Alzheimer's disease. Using a polyclonal antibody to the calcium-binding protein calretinin, we analyzed the possible changes in the subset of interneurons containing this protein in two neocortical areas that are generally devastated in Alzheimer's disease. In the prefrontal cortex as well as in the inferior temporal cortex, we observed no difference in the density of calretinin-immunoreactive neurons in Alzheimer's disease brains as compared to control cases. Moreover, the cellular morphology of these neurons was well preserved in the Alzheimer's disease cases. These data suggest that calretinin-immunoreactive neurons, like other calcium-binding protein-containing interneurons, are resistant to degeneration in Alzheimer's disease. The results support the notion that the pathological process in Alzheimer's disease involves specific cellular populations sharing particular morphological and neurochemical characteristics. In addition, it is possible that the presence of calcium-binding proteins confers a certain degree of resistance to degeneration in specific neuronal subsets.

Aged↗
PubMed1993

Presumptive Renshaw cells contain decreased calbindin during recovery from sciatic nerve lesions.

A subpopulation of calbindin-immunoreactive neurons in lamina VII of the spinal cord has been identified by its location as Renshaw cells, the anatomical substrate for recurrent inhibition. The expression of calbindin (28 kDa) in these calbindin-containing rat ventral horn interneurons was studied with immunocytochemistry after sciatic nerve injuries. One week after axotomy calbindin immunoreactivity was strongly reduced on the lesioned side between levels L4 and L6, while calbindin-containing neurons and fibers were still numerous contralaterally and cranially to the lesioned levels. With the progression of regeneration, calbindin-immunoreactive neurons reappeared, reaching a normal distribution 6-8 weeks after the crush. Similar changes could be mimicked by the intramuscular administration of botulinum toxin. These results suggest that calbindin expression in putative Renshaw cells of the spinal cord might be functionally responsive and that maintenance of calbindin expression may depend on the integrity of motoneurons and neuromuscular transmission.

Animals↗
PubMed1993

Intracellular concentration of parvalbumin in nerve cells.

Parvalbumin is supposed to function as an intracellular Ca2+ buffer in the brain, but its concentration in nerve cells is unknown. We combined radioimmunoassay of parvalbumin in rat brain extracts, together with image analysis of area fractions immunostained with the parvalbumin antibody on sections, to deduce the intracellular concentration of parvalbumin. We found that the average amount of parvalbumin varied between 6 microM in the caudatoputamen and 45 microM in the cerebellum. Although these values are only rough averages and do not demonstrate a Ca2+ buffering role for parvalbumin in neurons, the concentration of the protein is at least in the appropriate range for such a function.

Animals↗
PubMed1993

Distribution of parvalbumin immunoreactivity in the vertebrate retina.

Parvalbumin, a calcium-binding protein thought to buffer intracellular calcium, is expressed in selected neuronal and non-neuronal cell populations. We used a well-characterized antibody directed against parvalbumin to investigate the distribution of parvalbumin in the retina of twelve vertebrate species to evaluate patterns of cellular expression for recurrent functional features. Parvalbumin immunoreactivity was displayed by subpopulations of ganglion, amacrine, bipolar and horizontal cells in different species-specific combinations. In the pigeon retina, subpopulations of amacrine, ganglion and bipolar cells were immunoreactive for parvalbumin. Parvalbumin immunoreactive bipolar cells in this species were mostly confined to the temporal dorsal region of the retina. In the owl, no immunoreactive amacrine cells were found, but many bipolar cells displayed parvalbumin immunoreactivity. In the teleost retina, amacrine and ganglion cells were found to be immunoreactive for parvalbumin. A high degree of species-specific variation was encountered in the mammalian retina. The most consistent finding within this class was that subpopulations of parvalbumin-immunoreactive amacrine cells were consistently observed in every species. In the rabbit, horizontal and ganglion cells displaying parvalbumin immunoreactivity were also seen. In rodents (hamster, ground squirrel), parvalbumin immunoreactivity was displayed by subpopulations of amacrine cells and, in the squirrel, by some ganglion cells as well. In the cat and in the baboon retina, parvalbumin immunoreactivity was found in horizontal cells, ganglion cells and a subpopulation of amacrine cells. The distribution of parvalbumin immunoreactive neurons in the vertebrate retinae studied showed no systematic correlation with phylogenetic proximity. The expression of parvalbumin within the systems of retinal neurons may therefore reflect the functional needs of different visual behaviors.

Animals↗
PubMed1993

Parvalbumin and calretinin in the avian thymus.

The avian thymic hormone, known to support the maturation of T-lymphocytes, is biochemically similar to parvalbumin. However, its exact cellular distribution in the thymus is unknown. We have therefore studied the occurrence of parvalbumin and other related calcium-binding proteins in this organ by immunohistochemistry during development and after hatching. Parvalbumin immunoreactivity appears in the epithelial cells on embryonic day 9, and is expressed in the cortical reticular cells in the adult. Calretinin is found in the clusters of medullary epithelial cells from embryonic day 11, whereas calbindin D-28k is absent from this organ. Thus, calcium binding-proteins are excellent markers for different compartments of the avian thymus in embryonic life and after hatching, and their expression seems to coincide with their functional maturation.

Animals↗
PubMed1993

Developmental pattern and subcellular localization of parvalbumin in the rat tooth germ.

The EF-hand calcium-binding protein parvalbumin has been extensively studied in nerve and muscle cells. Its possible role in biomineralization during tooth development was here investigated by determining its subcellular localization by immunogold cytochemistry. The developmental sequences of amelogenesis and dentinogenesis were studied in rat molars, and in continuously growing rat incisors. The findings confirm that parvalbumin is a nuclear and a cytosolic protein, not associated with any particular intracellular organelle. Epithelial and mesenchymal undifferentiated cells contained no specific parvalbumin immunolabelling. In differentiated ameloblasts, secretory-pole (Tomes' process) formation was associated with a proximal-distal gradient of parvalbumin labelling. But after the Tomes' process had formed, parvalbumin was evenly distributed throughout the cell. The parvalbumin contents of ruffle-ended and smooth-ended ameloblasts appeared to be very different. Differentiated odontoblasts were less heavily labelled than ameloblasts, and the label was restricted to the cell body during the whole of dentinogenesis. These data suggest that parvalbumin could contribute to membrane plasticity during differentiation, as shown during dendritic growth in the nervous cells. Moreover, as may occur in excitable cells, parvalbumin could buffer calcium specifically in the cells producing mineralized enamel and dentine during the later stages of tooth development.

Ameloblasts↗
PubMed1993

Characterization of a polyclonal antiserum against the purified human recombinant calcium binding protein calretinin.

We have purified recombinant human calretinin (CR) from Escherichia coli lysates and have produced a polyclonal antiserum against it. The antiserum recognizes determinants conserved in fish, chicken, rat, monkey and human CR. We show its use in the qualitative detection of CR by different methods of immunohistochemistry as well as in the detection of CR on immunoblots.

Amino Acid Sequence↗