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PubMed1999

Math1: an essential gene for the generation of inner ear hair cells.

The mammalian inner ear contains the cochlea and vestibular organs, which are responsible for hearing and balance, respectively. The epithelia of these sensory organs contain hair cells that function as mechanoreceptors to transduce sound and head motion. The molecular mechanisms underlying hair cell development and differentiation are poorly understood. Math1, a mouse homolog of the Drosophila proneural gene atonal, is expressed in inner ear sensory epithelia. Embryonic Math1-null mice failed to generate cochlear and vestibular hair cells. This gene is thus required for the genesis of hair cells.

Animals↗
PubMed1999

Early neocortical regionalization in the absence of thalamic innervation.

There is a long-standing controversy regarding the mechanisms that generate the functional subdivisions of the cerebral neocortex. One model proposes that thalamic axonal input specifies these subdivisions; the competing model postulates that patterning mechanisms intrinsic to the dorsal telencephalon generate neocortical regions. Gbx-2 mutant mice, whose thalamic differentiation is disrupted, were investigated. Despite the lack of cortical innervation by thalamic axons, neocortical region-specific gene expression (Cadherin-6, EphA-7, Id-2, and RZR-beta) developed normally. This provides evidence that patterning mechanisms intrinsic to the neocortex specify the basic organization of its functional subdivisions.

Animals↗
PubMed2004

Non-neoplastic granulosa cells within ovarian vascular channels: a rare potential diagnostic pitfall.

AIMS: To describe six cases seen in consultation in which artefactual vascular involvement within the ovary by benign granulosa cells caused diagnostic confusion. METHODS/RESULTS: In five cases, the initial favoured diagnoses of the submitting pathologists were metastatic carcinoma (three cases) and immature neural elements within a teratoma (two cases). In two cases, the ovary contained a benign cystic teratoma (one with struma ovarii), in two cases endometriosis, in one case follicular cysts, and in the other no pathological lesion was present. In all cases, several small ovarian vascular channels contained cohesive groups of cells with mildly atypical nuclei and cytoplasm, which varied from scant to abundant and eosinophilic. In four cases, mitotic figures were identified. The cells were morphologically consistent with benign granulosa cells and were associated in four cases with a nearby follicle lined by similar cells. There was no evidence of a mass lesion, grossly or histologically, to suggest a granulosa cell tumour. The nature of the cells was confirmed using immunohistochemistry for alpha inhibin and calretinin in one case. CONCLUSIONS: This phenomenon is probably an artefact secondary to surgical trauma or sectioning within the laboratory; alternatively, it could be related to ovulation. It is important that this benign process is not misinterpreted as cancer, either primary or metastatic, which may prompt inappropriate treatment or investigations that are not needed.

Adult↗
PubMed2004

The loss of calretinin expression indicates aganglionosis in Hirschsprung's disease.

BACKGROUND: Hirschsprung's disease (HD) is a congenital disorder characterised by the absence of ganglion cells in the large bowel, leading to functional obstruction and colonic dilatation proximal to the affected segment. A subclass of nerve cell bodies in both submucosa and myenteric ganglia of the human gastrointestinal tract were found to show immunopositivity for calretinin, a calcium binding protein, which plays an important role in the organisation and functioning of the central nervous system. AIM: To investigate calretinin immunostaining in ganglionic and aganglionic HD colon specimens, and compare it with staining for S100, neurone specific enolase, and c-kit. METHODS: Ten large bowel, full thickness specimens from patients with classic rectosigmoid HD were selected from the pathology repository. In total, 54 paraffin wax blocks-24 from the ganglionic zone, 17 from the aganglionic zone, and 13 from the transitional zone-were processed. RESULTS: Calretinin was not expressed in aganglionic segments of HD and associated nerve fibres, whereas in ganglionic HD segments and in normal colon both ganglion cells and nerve fibres were immunopositive. In addition, c-kit showed an altered distribution in the interstitial cells of Cajal. The transitional zone showed a broad spectrum of histomorphological and immunohistochemical patterns of both calretinin and c-kit expression. CONCLUSION: The absence of calretinin expression may serve as a diagnostic aid in identifying aganglionic segments in HD.

Adult↗
PubMed2003

Inhibin is more specific than calretinin as an immunohistochemical marker for differentiating sarcomatoid granulosa cell tumour of the ovary from other spindle cell neoplasms.

AIMS: To describe a case of recurrent sarcomatoid adult granulosa cell tumour (AGCT) of the ovary and to evaluate the usefulness of two ovarian sex cord stromal markers (inhibin and calretinin) in separating sarcomatoid AGCT from true sarcomas. METHODS: A 72 year old woman presented with a recurrent sarcomatoid AGCT in the sigmoid colon mesentery, which histologically mimicked a malignant gastrointestinal stromal tumour (GIST). This index case and 79 sarcomas (32 GISTs, 28 leiomyosarcomas, 15 endometrial stromal sarcomas (ESSs), including one with sex cord-like areas, and four undifferentiated uterine sarcomas) were immunostained using antibodies to inhibin and calretinin. RESULTS: The recurrent sarcomatoid AGCT expressed diffuse, strong cytoplasmic immunoreactivity with inhibin and focal but strong nuclear and cytoplasmic positivity with calretinin. Focal, weak cytoplasmic inhibin expression limited to sex cord-like areas was present in one ESS. None of the other sarcomas expressed inhibin. Focal, strong calretinin immunoreactivity was identified in 11 leiomyosarcomas and one GIST. The case of ESS with sex cord-like areas showed strong immunoreactivity for calretinin limited to the sex cord-like areas. CONCLUSIONS: Inhibin is a useful immunomarker to distinguish sarcomatoid AGCT from other spindle cell neoplasms that may enter into the differential diagnosis. Calretinin appears to be less specific than inhibin.

Aged↗
PubMed2006

Renal compensation to chronic hypoxic hypercapnia: downregulation of pendrin and adaptation of the proximal tubule.

The molecular basis for the renal compensation to respiratory acidosis and specifically the role of pendrin in this condition are unclear. Therefore, we studied the adaptation of the proximal tubule and the collecting duct to respiratory acidosis. Male Wistar-Hannover rats were exposed to either hypercapnia and hypoxia [8% CO(2) and 13% O(2) (hypercapnic, n = 6) or normal air (controls, n = 6)] in an environmental chamber for 10 days and were killed under the same atmosphere. In hypercapnic rats, arterial pH was lower than controls (7.31 +/- 0.01 vs. 7.39 +/- 0.01, P = 0.03), blood HCO(3)(-) concentration was increased (42 +/- 0.9 vs. 32 +/- 0.24 mM, P < 0.001), arterial Pco(2) was increased (10.76 +/- 0.4 vs. 7.20 +/- 0.4 kPa, P < 0.001), and plasma chloride concentration was decreased (92.2 +/- 0.7 vs. 97.2 +/- 0.5 mM, P < 0.001). Plasma aldosterone levels were unchanged. In the proximal tubule, immunoblotting showed an increased expression of sodium/bicarbonate exchanger protein (188 +/- 22 vs. 100 +/- 11%, P = 0.005), confirmed by immunohistochemistry. Total Na/H exchanger protein expression in the cortex was unchanged by immunoblotting (119 +/- 10 vs. 100 +/- 11%, P = 0.27) and immunohistochemistry. In the cortex, the abundance of pendrin was decreased (51 +/- 9 vs. 100 +/- 7%, P = 0.003) by immunoblotting. Immunohistochemistry revealed that this decrease was clear in both cortical collecting ducts (CCDs) and connecting tubules (CNTs). This demonstrates that pendrin expression can be regulated in acidotic animals with no changes in aldosterone levels and no external chloride load. This reduction of pendrin expression may help in redirecting the CNT and CCD toward chloride excretion and bicarbonate reabsorption, contributing to the increased plasma bicarbonate and decreased plasma chloride of chronic respiratory acidosis.

Acidosis, Respiratory↗
PubMed2004

Comparative morphology of rodent vestibular periphery. I. Saccular and utricular maculae.

Calyx afferents, a group of morphologically and physiologically distinct afferent fibers innervating the striolar region of vestibular sensory epithelia, are selectively labeled by antibodies to the calcium-binding protein calretinin. In this study, the population of calretinin-stained calyx afferents was used to delineate and quantify the striolar region in six rodent species: mouse, rat, gerbil, guinea pig, chinchilla, and tree squirrel. Morphometric studies and hair cell and calyx afferent counts were done. Numbers of hair cells, area, length, and width of the sensory epithelium increase from mouse to tree squirrel. In the mouse and rat, calretinin is found in 5-9% of all type I hair cells, 20-40% of striolar type II hair cells, and 70-80% of extrastriolar type II hair cells. Numbers of calyx afferents increase from mouse to squirrel, with more complex calyx afferents in larger species. About 10% of calyx afferents are branched. Based on our counts of total numbers of calyx afferents in chinchilla maculae and in comparison to fiber counts in the literature, the proportion of calyx afferents is greater than previously described, constituting nearly 20% of the total. Because morphometric measures increase with body weight, we obtained additional data on vestibular end organ surface areas from the literature and used this to construct a power law function describing this relationship. The function holds for species with body weights less than approximately 4 kg. Greater than 4 kg, the surface area of the sensory epithelia remains constant even with increasing body weight.

Afferent Pathways↗
PubMed2004

Comparative morphology of rodent vestibular periphery. II. Cristae ampullares.

We made flattened neuroepithelial preparations of horizontal and vertical (anterior and posterior) cristae from mouse, rat, gerbil, guinea pig, chinchilla, and tree squirrel. Calretinin immunohistochemistry was used to label the calyx class of afferents. Because these afferents are restricted to the central zone of the crista, their distribution allowed us to delineate this zone. In addition to calyx afferents, calretinin also labels approximately 5% of type I hair cells and 20% of type II hair cells throughout the mouse and rat crista epithelium. Measurements of the dimensions of the cristae and counts of hair cells and calyx afferents were determined on all species. Numbers of calyx afferents, hair cells, area, length, and width of the sensory epithelium increase from mouse to tree squirrel. As in the companion paper, we obtained additional data on vestibular end organ dimensions from the literature to construct a power law function describing the relationship between crista surface area and body weight. The vertical cristae of the mouse, rat, and gerbil have an eminentia cruciatum, a region located transversely along the midpoint of the sensory organ and consisting of nonsensory cells. Apart from this eminentia cruciatum, there are no statistical differences between horizontal and vertical cristae with regard to area, width, length, the number and type of hair cells, and number of calretinin-labeled calyx afferents.

Afferent Pathways↗
PubMed2005

Evaluation of a panel of molecular markers for the diagnosis of malignant serous effusions.

PURPOSE: Our main goal was to evaluate a panel of molecular markers for the detection of cancer cells in serous effusions and to determine their value as an adjunctive reverse transcription-PCR (RT-PCR) test to cytologic examination. EXPERIMENTAL DESIGN: One hundred fourteen serous effusions from 71 patients with tumors and 43 patients with benign diseases were subjected to RT-PCR for expression of carcinoembryonic antigen (CEA), epithelial cell adhesion molecule (Ep-CAM), E-cadherin, mammaglobin, mucin 1 (MUC1) isoforms MUC1/REP, MUC1/Y, and MUC1/Z, calretinin, and Wilms' tumor 1 susceptibility gene. RESULTS: CEA, Ep-CAM, E-cadherin, and mammaglobin were specifically expressed in malignant effusions. The sensitivity of RT-PCR in cytologically negative malignant effusions was 63.1% combining CEA and Ep-CAM (with 100% specificity) and reached 78.9% adding MUC1/Y or MUC1/Z (with 93% specificity). In the whole population of effusions, the combination of cytology with RT-PCR of CEA and Ep-CAM yielded a 90.1% sensitivity, a specificity and a positive predictive value of 100%, and a 86% negative predictive value for malignancy. Adding MUC1/Y or MUC1/Z to the panel, the sensitivity was 94.5% with 93% specificity, 95.7% PPV, and 90.9% negative predictive value. Moreover, CEA and mammaglobin were specifically expressed in epithelial malignancies, and mammaglobin was mainly expressed in effusions from breast carcinoma (97.3% of specificity). CONCLUSIONS: A combination of cytology and RT-PCR analysis of CEA and Ep-CAM significantly improved the detection sensitivity of tumor cells in serous effusions. RT-PCR analysis of CEA, Ep-CAM, and mammaglobin in serous effusions could be a beneficial adjunct to cytology for the diagnosis of malignancy.

Aged↗
PubMed2004

The claustrum is not missing from all monotreme brains.

Many authors have reported that the claustrum, which comprises the insular claustrum and the endopiriform nucleus, is missing from the monotreme forebrain. We used Nissl and myelin staining in conjunction with enzyme histochemistry for acetylcholinesterase and immunohistochemistry for parvalbumin, calbindin, calretinin and tyrosine hydroxylase to examine the brains of two monotremes, the short-beaked echidna (Tachyglossus aculeatus) and the platypus (Ornithorhynchus anatinus). We found that although the insular claustrum is a small structure in the echidna brain, it is nevertheless clearly present as loosely clustered neurons embedded in the white matter ventrolateral to the putamen and deep to the piriform and entorhinal cortices. Neurons in this region share the chemical features of the adjacent cortex (presence of a similar proportion of parvalbumin immunoreactive neurons and minimal activity for acetylcholinesterase and tyrosine hydroxylase), unlike the adjacent putamen and ventral pallidum. A putative endopiriform nucleus can be identified in the interior of the piriform lobe of the echidna as calretinin immunoreactive neurons embedded within the white matter. The situation is much less clear in the platypus, but our data suggest that there may be an insular claustrum deep to frontal cortex, separated from layer VI by only a thin layer of white matter. We could not identify an endopiriform nucleus in our platypus material. Our findings indicate that presence of the claustrum cannot be considered a feature confined to therian mammals and lend weight to arguments that this structure was present in the ancestral mammalian brain.

Acetylcholinesterase↗
PubMed2007

Loss of embryonic MET signaling alters profiles of hippocampal interneurons.

Hippocampal interneurons arise in the ventral forebrain and migrate dorsally in response to cues, including hepatocyte growth factor/scatter factor which signals via its receptor MET. Examination of the hippocampus in adult mice in which MET had been inactivated in the embryonic proliferative zones showed an increase in parvalbumin-expressing cells in the dentate gyrus, but a loss of these cells in the CA3 region. An overall loss of calretinin-expressing cells was seen throughout the hippocampus. A similar CA3 deficit of parvalbumin and calretinin cells was observed when MET was eliminated only in postmitotic cells. These data suggest that MET is required for the proper hippocampal development, and embryonic perturbations lead to long-term anatomical defects with possible learning and memory dysfunction.

Animals↗
PubMed1997

Calretinin in the rat pituitary: colocalization with thyroid-stimulating hormone.

The purpose of this study was to examine the distribution of calretinin immunoreactivity (CR) in the male rat pituitary gland by immunofluorescence microscopy. CR was found in cells of the anterior pituitary and in granules in the posterior pituitary. In the intermediate lobe, nerve fibers in close proximity to the melanotropes were CR-immunoreactive (CR-ir). Fine CR-ir varicose fibers were also observed in the anterior and posterior pituitary. Colocalization studies revealed that the majority of the CR-containing cells of the anterior pituitary also contained thyroid-stimulating hormone (TSH). These CR/TSH cells represented about 32% of the thyrotrope population. Following thyroidectomy, a massive increase in both the number of CR-ir cells and in the expression of CR mRNA was observed in the anterior pituitary. Thyroxine treatment, however, resulted in a reduction in the number and size of the CR-ir cells in the same lobe. In the intermediate lobe, CR-ir was colocalized with tyrosine hydroxylase (TH) immunoreactive dopaminergic fibers. These intermediate lobe fibers disappeared following pituitary stalk section, as did the CR/TH fibers and the CR-ir granular material in the posterior pituitary. The findings in the anterior pituitary suggest that consideration be given to the idea that CR might function in the synthesis and/or release mechanism of TSH in thyrotropes and that its expression is modulated by the hypothalamo-pituitary-thyroid axis.

Animals↗
PubMedDate not supplied

Calretinin. A selective marker of normal and neoplastic mesothelial cells in serous effusions.

OBJECTIVE: To document that a polyclonal antiserum to calretinin, a 29-kd calcium-binding protein, consistently decorates normal and tumor mesothelial cells in cytologic preparations. STUDY DESIGN: Thirty-three archival cytologic specimens from eight patients with histologically confirmed malignant mesothelioma and 13 from patients with metastatic serous effusions were destained and then immunostained with anticalretinin antiserum. For investigation of cell suspensions, four pleural fluids were incubated with anticalretinin antiserum. After cytocentrifugation the specimens were stained in accordance with the alkaline phosphatase anti-alkaline phosphatase (APAAP) method. For electron microscopic examination the cell suspensions were then incubated with gold-labeled antirabbit antibody. RESULTS: The diagnostic sensitivity of this new immunocytochemical approach reached 100% for the eight malignant mesotheliomas investigated. Only 3 of the 13 adenocarcinomas metastatic to the serous membranes included in this study were weakly reactive, accounting for 81% specificity. Binding of anticalretinin antiserum to living mesothelial cells was consistently documented in all four cases investigated. CONCLUSION: Calretinin is a very useful marker for positive identification of normal and tumor mesothelial cells in serous effusions.

Adenocarcinoma↗
PubMed2003

Incorporation of murine brain progenitor cells into the developing mammalian retina.

PURPOSE: To investigate the influence of a developing host environment on the survival, differentiation, and morphologic integration of murine brain progenitor cells (mBPCs) transplanted into the mammalian retina. METHODS: Enhanced green fluorescent protein (GFP)-expressing murine brain progenitor cells were transplanted into developing and mature Brazilian opossums (Monodelphis domestica). Animals were allowed to survive for up to 4 weeks after transplantation, at which time the eyes were prepared for immunohistochemical analysis. RESULTS: Transplanted mBPCs survived and differentiated in vivo, and extensive morphologic integration was observed within the host retinas. GFP-expressing cells often displayed morphologies characteristic of retinal neurons. GFP somata were located in nuclear layers, and their processes ramified throughout the inner (IPL) and outer (OPL) plexiform layers. Furthermore, in some cases, GFP-expressing neurites were confined to specific sublamina within the IPL. The greatest morphologic integration and differentiation were observed after transplantation into the youngest-aged host eyes. Some transplanted mBPCs incorporated within the inner retina expressed the neuronal markers microtubule associated protein (MAP)-2 or calretinin. Transplanted cells coexpressed GFP and recoverin only in the ONL. CONCLUSIONS: mBPCs survived and morphologically integrated after xenotransplantation without immunosuppression. mBPCs were capable of incorporating into specific layers of the retina and expressing neuronal and retinal markers. The age of the host appeared to play a key role in determining cell fate in vivo.

Animals↗
PubMed2006

Neuroglobin and cytoglobin: oxygen-binding proteins in retinal neurons.

PURPOSE: The goal of this study was to describe the detailed localization of the novel oxygen-binding molecules, neuroglobin (Ngb) and cytoglobin (Cygb), in mammalian retinas and to determine whether Ngb and Cygb are neuronal or glial proteins in the retina. METHODS: Antibodies directed against Ngb and Cygb were used to examine their patterns of distribution in normal canine retinas. Immunoblot analysis was performed to verify antibody specificity and the presence of Ngb and Cygb in canine tissues. Double-labeling immunohistochemistry was performed with the Ngb and Cygb antibodies along with antibodies against neuronal (MAP-2, class III beta-tubulin (TUJ1), PKCalpha, and calretinin) and glial antigens (vimentin and CRALBP). Tissue sections were analyzed with light and confocal microscopy. RESULTS: Ngb and Cygb proteins were observed in different retinal cells. Cygb (but not Ngb) was also present in canine kidney, liver, lung, and heart tissue. Immunohistochemical analysis of canine retinas demonstrated Ngb immunoreactivity (IR) in the ganglion cell layer (GCL), inner (INL) and outer (ONL) nuclear layers, inner (IPL) and outer plexiform (OPL) layers, photoreceptor inner segments (IS), and retinal pigment epithelium (RPE). Ngb IR was localized within retinal neurons, but not in glia. Cygb IR was found in neurons and their processes in the GCL, IPL, INL, and OPL and within the RPE, but not in glia. CONCLUSIONS: Ngb and Cygb are widely distributed in retinal neurons and RPE, but not in glial cells of the canine retina. Their structure and distribution is suggestive of a possible role in oxygen transport in the mammalian retina.

Animals↗
PubMed2003

Expression of Notch1 and Jagged2 in the enteric nervous system.

The Notch signaling pathway is a vitally important pathway in regulating brain development. To explore the involvement of the Notch pathway in neuronal cells of adult rat gut, we investigated the expression of Notch1 and Jagged2 by in situ hybridization (ISH) and immunohistochemistry (IHC). In the enteric nervous system, Notch1 and Jagged2 were expressed in ganglia of the submucosal and myenteric plexus. Notch1 was preferentially expressed in cholinergic neurons lacking calretinin or nitric oxide synthase (NOS), whereas Jagged2 was present in most neuron subtypes. We propose that Notch1 and Jagged2 have a continuing role in the maintenance and function of neuronal cells in the adult enteric nervous system.

Animals↗
PubMed2005

Tissue models of peritoneal fibrosis.

OBJECTIVE: To evaluate the utility of peritoneal pathologic samples, unrelated to peritoneal dialysis (PD) treatment, for the study of peritoneal fibrosis and inflammation. METHODS: Comparative morphologic and immunohistochemical study of peritoneal pathologic samples unrelated to PD with peritoneal biopsies from PD patients with special emphasis on the expression of myofibroblastic and epithelial-to-mesenchymal transition markers. RESULTS: Regarding morphology, PD-related simple fibrosis was less cellular, with greater stromal hyalinization, determining a homogeneous, hypocellular aspect of the submesothelium. In contrast, non-PD fibrosis was more cellular with an extracellular matrix showing a dense and fibrillar quality with wide bundles of collagen. Hylinazing vasculopathy was only present in PD samples. Myofibroblastic differentiation and epithelial-to-mesenchymal transition were common findings in all situations of peritoneal fibrosis. Calponin and calretinin are useful cellular markers to study such fibrogenic mechanisms and correlate with other well-known markers such as a -SMA and cytokeratins. Their expression was much more intense in those samples showing acute inflammation (peritonitis). CONCLUSIONS: Non-PD models of peritoneal fibrosis seem very useful to evaluate important features of human peritoneal pathology such us fibrogenesis, and inflammation. Fibrogenic events such as myofibroblastic differentiation and epithelial-to-mesenchymal transition are evident in these tissue samples allowing us to use them as an accessible source for in vivo and ex vivo studies. Both events show their maximal expression in situations of acute inflammation supporting the important role that peritonitis episodes play in the progression of fibrosis.

Actins↗