Nuclear Immunolabeling Research Articles

Assessment of SOX10 expression in 437 canine neoplasms of different embryologic origins.

Several members of the SRY-related HMG-box (SOX) protein family are implicated in tumorigenesis, metastasis, and regulation of the tumor microenvironment. SOX10, which is involved in neural crest cell migration and differentiation, has long been recognized a sensitive and specific immunohistochemical (IHC) marker in the diagnosis of melanoma in humans. However, expression of SOX10 in other tumor types has infrequently been evaluated in humans until recently and has not been thoroughly investigated in the dog. Our aim was to characterize the expression of SOX10 in canine neoplasms to objectively assess its value as a diagnostic IHC marker. Immunohistochemistry for SOX10 was performed on 437 archived, formalin-fixed paraffin-embedded tissues from representative canine neoplasms of ectodermal (15 tumor types), mesodermal (13 tumor types), endodermal (8 tumor types), and mixed/unknown (7 tumor types) embryologic origin. Oral and cutaneous tumors of melanocytic origin were used as positive controls. Intense SOX10 immunolabeling was observed in most tumors of ectodermal origin, including consistent expression in mammary carcinomas, and gliomas. Embryonal and hair follicle neoplasms inconsistently exhibited strong nuclear immunolabeling. Oral fibrosarcomas and undifferentiated oral sarcomas both inconsistently exhibited moderate to strong nuclear immunolabeling. Neoplasms of mesodermal and endodermal origin lacked immunolabeling. Salivary carcinomas, representing an unknown/mixed embryologic origin, were strongly labeled. SOX10 expression is not limited to melanomas, but is expressed by canine tumors of diverse tissues and embryologic derivation. Importantly, expression of SOX10 by a subset of oral sarcomas impairs its value as a marker for spindle cell oral melanomas.

Primary and secondary leptomeningeal gliomatosis in dogs.

Leptomeningeal gliomatosis (LG) is characterized by extensive dissemination of neoplastic glial cells in the subarachnoid space either without an intraparenchymal glioma (primary LG or PLG) or secondary to an intraparenchymal glioma (secondary LG or SLG). Given the low frequency of LG in human and veterinary medicine, specific diagnostic criteria are lacking. Here, we describe 14 cases of canine LG that were retrospectively identified from 6 academic institutions. The mean age of affected dogs was 7.3 years and over 90% of patients were brachycephalic. Clinical signs were variable and progressive. Relevant magnetic resonance image findings in 7/14 dogs included meningeal enhancement of affected areas and/or intraparenchymal masses. All affected dogs were euthanized because of the poor prognosis. Gross changes were reported in 12/14 cases and consisted mainly of gelatinous leptomeningeal thickening in the brain (6/12 cases) or spinal cord (2/12 cases) and 1 or multiple, gelatinous, gray to red intraparenchymal masses in the brain (6/12 cases). Histologically, all leptomeningeal neoplasms and intraparenchymal gliomas were morphologically consistent with oligodendrogliomas. Widespread nuclear immunolabeling for OLIG2 was observed in all neoplasms. The absence of an intraparenchymal glioma was consistent with PLG in 3 cases. The remaining 11 cases were diagnosed as SLG.

Characterization of novel papillomavirus from free-ranging Antillean manatee Trichechus manatus manatus with genital papillomatosis.

The Antillean manatee Trichechus manatus manatus is an Endangered species living along the Atlantic coasts of the Americas from Florida (USA), throughout the Caribbean, to Brazil. In July 2020, a manatee with multiple wounds due to boat-inflicted trauma was rescued from the coast east of Cayo Mata, Salinas, Puerto Rico. This manatee had neutropenia, leukopenia, and monocytosis associated with immunosuppression and nutritional deficiency anemia, as well as bacteria and fungi within the lesions. The manatee had genital lesions which included papules and linear plaques, microscopically characterized by mucosal hyperplasia with cytopathic changes typical of papillomavirus infection. Superficial epithelial cells had strong nuclear immunolabeling when examined using a monoclonal antibody specific to papillomavirus. The sequencing data of PCR products with papillomavirus-specific degenerative primers indicated that these lesions contained a novel manatee papillomavirus (Trichechus manatus papillomavirus, TmPV). The genomic DNA was amplified using a rolling circle amplification, and fully sequenced to be 7586 bp (GenBank accession no. OK073977). Other TmPVs were previously isolated from Florida manatees T. manatus latirostris. This novel virus was designated TmPV type 5 (TmPV5) based on its genomic characterization and sequence comparison. The TmPV5 genome shared 50.7, 48.9, 69.4, and 62.1% similarities with TmPV1, TmPV2, TmPV3, and TmPV4, respectively. TmPV5 is classified in the genus Rhopapillomavirus together with other manatee papillomaviruses. After 2.5 mo of veterinary treatment and rehabilitation, the manatee recovered and was released. This is the first report of papillomatosis in a free-ranging Antillean manatee.

Piloleiomyosarcoma in cats: Histological and immunohistochemical features.

This study describes the histomorphology and immunohistochemical profile of 9 cases of feline piloleiomyosarcoma. Cats ranged in age from 7 to 16 years (mean 10), and tumors were 7 to 24 mm in diameter (mean 15). Tumors were composed of fusiform cells that were haphazardly arranged or in variably sized interwoven bundles. Neoplastic cells had eosinophilic and fibrillar cytoplasm, and elongated blunt-ended nuclei. Entrapment of hair follicles and absence of vascular components support an origin from the smooth muscle cells of the arrector pili. Additional findings included bizarre nuclei and giant cells (7/9 cases), atypical mitoses (7/9 cases), ulceration (3/9 cases), and intratumoral necrosis (6/9 cases). Neoplastic cells expressed calponin, desmin, α-smooth muscle actin, and vimentin, but not CD18, CD31, cytokeratins, glial fibrillary acidic protein, neuron-specific enolase, Melan A, p63, or S-100 protein. Surgical excision was curative in 6/9 cases, with local recurrence in 2/9 cases and metastasis to local lymph nodes in 1/9 case. Clinical outcome was influenced by mitotic count, infiltration of subcutaneous tissue, and intensity of nuclear immunolabeling for p53.

Canine Gliomatosis Cerebri: Morphologic and Immunohistochemical Characterization Is Supportive of Glial Histogenesis.

Gliomatosis cerebri (GC) is a glioma subtype with diffuse neuroparenchymal infiltration without architectural distortion. GC was first used in human neuropathology and remained controversial until its elimination from the diagnostic lexicon in 2016. GC is currently defined as a diffuse growth pattern of glioma rather than a distinct entity. In this article, we characterize 24 cases of canine GC and classify these neoplasms as diffuse gliomas. Selected cases of canine GC were reviewed and immunolabeled for oligodendrocyte lineage transcription factor 2 (Olig2), glial fibrillary acidic protein (GFAP), and 2',3'-cyclic-nucleotide 3'-phosphodiesterase (CNPase). The mean age of affected dogs was 7 years, and 9 were brachycephalic. Gross lesions (8 cases) consisted mainly of parenchymal swelling. Histologically, of the 24 cases, there was widespread infiltration of neoplastic cells with astrocytic (12 cases), oligodendroglial (8 cases), or mixed morphology (4 cases) in the brain (18 cases), spinal cord (4 cases), or both (2 cases). Secondary structures occurred across different tumor grades and were not restricted to high-grade neoplasms. Astrocytic neoplasms had moderate nuclear immunolabeling for Olig2 and robust cytoplasmic immunolabeling for GFAP. Oligodendroglial neoplasms had robust nuclear immunolabeling for Olig2, moderate or absent cytoplasmic immunolabeling for GFAP, and moderate cytoplasmic immunolabeling for CNPase. Tumors with mixed morphology had robust nuclear immunolabeling for Olig2 and variable cytoplasmic immunolabeling for GFAP and CNPase. Morphologic and immunohistochemical features confirmed a glial histogenesis for all tumors and allowed for their classification as diffuse, low- or high-grade astrocytoma; oligodendroglioma; or undefined glioma. Further research is needed to confirm or refute the hypothesis that canine GC represents an infiltrative growth pattern of canine glioma.

Journal-related Activities and Other Special Activities at the 2020 American Society of Anesthesiologists Meeting.

Journal-related Activities and Other Special Activities at the 2020 American Society of Anesthesiologists Meeting.

Gene of the month: TFE 3

Transcription factor enhancer 3 (TFE3), on the short arm of chromosome Xp11.23 and its protein, belongs to the microphthalmia transcription family (MiTF) of transcription factors. It shares close homology with...

Immunoexpression of BAP1, ROS1, and ALK in Spitzoid Melanocytic Tumors.

Spitzoid tumors are a heterogeneous group of melanocytic neoplasms that frequently imposes diagnostic difficulties. Lately, several advances in molecular biology afforded significant discoveries on the pathogenesis of these tumors. BAP1 (BRCA-1 associated protein-1) inactivation and anomalous expression of kinase translocation-related proteins are among the main criteria launched by new classification proposals. Our aim was to systematically assess the immunoexpression of BAP1, ROS1 (receptor tyrosine kinase c-Ros oncogene 1), and ALK (anaplastic lymphoma receptor tyrosine kinase) proteins in an unpublished series of spitzoid tumors. Retrospective study based on 47 formalin-fixed paraffin-embedded tissue samples from 3 different institutions. BAP1, ROS1, and ALK immunostains were performed in all cases. We included 27 Spitz tumors without significant abnormality, 15 atypical spitzoid tumors, and 5 spitzoid melanomas. We observed loss of BAP1 nuclear immunolabeling in 4.3% of evaluable cases (2/46), both of them atypical spitzoid tumors. The proportional frequency of BAP1-inactivated cases among atypical spitzoid tumors was 14.2% (2/14). No immunoexpression of ROS1 or ALK was found. Our study revealed 2 additional BAP1-inactived cases and described its respective frequency. The absence of anomalous expression of translocation-related proteins ALK and ROS1 in this series, composed predominantly of low-grade/low-risk tumors, indicates that translocated spitzoid lesions may not be as prevalent as initially suggested, at least in some populations. Furthermore, our findings encourage additional investigation on unequal occurrence of such immunomarkers among different diagnostic categories of spitzoid neoplasms.

Stress-induced dendritic internalization and nuclear translocation of the neurokinin-3 (NK3) receptor in vasopressinergic profiles of the rat paraventricular nucleus of the hypothalamus

Central neuronal circuits that relay stress information include vasopressin- (AVP) and oxytocin- (OC) containing neurons of the paraventricular nucleus of the hypothalamus (PVN). These neurons are potentially modulated by neurokinin-3 receptors (NK3Rs) of the tachykinin family of neuropeptides. NK3Rs have been localized in PVN neurons and have showed nuclear translocation following an osmotic challenge in rodents. However, their subcellular distribution in AVP or OC neurons of the PVN and plasticity following restraint stress in rats are unknown. In the present study, densities of NK3Rs in PVN AVP- or OC-labeled somatodendritic profiles were measured by quantitative immunoelectron microscopy in control or stressed rats. In resting conditions, NK3Rs were predominantly located in AVP neurons, however sparsely distributed in OC neurons of the PVN. All NK3-labeled somata of the PVN in control rats showed cytoplasmic but no nuclear immunolabeling. An acute restraint stress session of 30min significantly increased nuclear NK3R density in AVP-labeled somata but not in OC-labeled somata. These changes were accompanied by a respective decrease and increase in plasmalemmal and cytoplamic NK3R densities in AVP-labeled but not in OC-labeled dendrites. The results of this study suggest that in the rat PVN 1) NK3R distribution is conducive to modulation of systemic and/or central AVP release through PVN inputs to the posterior pituitary and/or the amygdala and 2) acute restraint stress activates (internalizes) NK3Rs on surface and evokes nuclear NK3R translocation exclusively in AVP neurons. This trafficking might contribute to neurochemical imbalances observed in neuronal circuits involved in stress-related disorders such as anxiety.

Survivin and Related Proteins in Canine Mammary Tumors

Survivin is reexpressed in most human breast cancers, where its expression has been associated with tumor aggressiveness, poor prognosis, and poor response to therapy. Survivin expression was evaluated in 41 malignant canine mammary tumors (CMTs) by immunohistochemistry, in relation to histological grade and stage, and correlated with that of some related molecules (β-catenin, caspase 3, heat shock proteins) to understand their possible role in canine mammary tumorigenesis. An increase in nuclear survivin expression, compared with healthy mammary glands, was observed in CMTs, where nuclear immunolabeling was related to the presence of necrosis. No statistically significant relation was found between the expression of the investigated molecules and the histological grade or stage. The present study may suggest an important involvement of survivin in CMT tumorigenesis. Its overexpression in most of the cases evaluated might suggest that targeting survivin in CMTs may be a valid anticancer therapy.

Abstract C148: Expression and activation of p38 in papillary thyroid carcinoma.

Abstract Introduction: Papillary thyroid cancer (PTC) is the commonest endocrine malignancy. PTC frequently carries several alterations in genes coding for proteins that activate the mitogen-activated protein kinase (MAPK) signaling pathway, which plays a key role in the regulation of cell growth, differentiation, and survival. The present study aims to investigate the MAPK signal transduction pathway [extracellular-regulated kinase (ERK), Jun N-terminal Kinase (JNK) and p38] involved in tumorigenesis of PTC. Experimental procedures: Twenty samples of PTC and its follicular variant (11 classic PTC, 9 follicular variant of PTC) were retrieved from the UCL biolibrary. Corresponding paraffin blocks were selected for immunohistochemical analysis of total and phosphorylated forms of ERK, JNK and p38. Percentage of immunolabeled cells in tumors was graded as: slight staining in less than 10% of tumor cells; mild staining in 10-30%; moderate staining in 30-50% and abundant staining in more than 50 % of tumor cells. In addition, frozen sections of the same tumors were solubilized to perform Western blots of total and phosphorylated p38. Results: ERK activation was seen as nuclear immunolabeling in 15/ 20 PTC cases in less than 10% of tumor cells. JNK activation was seen in 7/20 cases in less than 10% of tumor cells as nuclear and membranous immunolabeling. However, total ERK and total JNK was seen as nuclear and cytoplasmic immunolabeling in 10/20 and 16/20 cases respectively in more than 50% of tumor cells. p38 MAPK phosphorylation was seen as abundant nuclear and cytoplasmic immunolabeling in 11/20 cases (6 follicular variants of PTC and 5 classic PTC). Total p38 was immunolabeled in 14/20 cases. A one-way ANOVA test showed significant difference between the ERK, JNK and p38 phosphorylation (p<0.01). By Western blotting, p38 was detected in all twenty PTC samples and its phosphorylated form was detected in 17/20 samples. The signals were much stronger in the follicular variants of PTC as compared to classic PTC. p38 was also detected in normal thyroid tissue but not its phosphorylated form. Conclusions: There is variable expression and activation of the MAPK pathways in PTC but p38 appears to be activated in a larger proportion of PTC than ERK or JNK. The role of p38 in tumorigenesis of PTC and its variable expression in different variants of PTC will be further investigated. The molecular profiling of PTC should help to better understand the altered biological pathways involved in the genesis of this cancer. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):C148. Citation Format: Monika Lamba Saini, Birgit Weynand, Jacques Rahier, Michel Mourad, Marc Hamoir, Etienne Marbaix. Expression and activation of p38 in papillary thyroid carcinoma. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr C148.

Review of renal carcinoma with t(6;11)(p21;q12) with focus on clinical and pathobiological aspects.

Recently, a new category of MiTF/TFE family translocation carcinomas of the kidney has been proposed. This category includes Xp11.2 renal cell carcinoma (RCC) and the t(6;11) RCC. These tumors share clinical, morphological, immunohistochemical and molecular genetic features. In this article, we review t(6;11) RCC. This tumor predominantly affects children and young adults. Macroscopically, the tumor generally forms a well circumscribed mass. Satellite nodules may be observed. Histologically, the tumor comprises large cells and small cells surrounded by basement membrane material. Immunohistochemically, tumor cells show nuclear immunolabeling for TFEB and usually express Cathepsin-K in the cytoplasm. Karyotyping detects the rearrangement between chromosome 6p21 and chromosome 11q12. Alpha-TFEB fusion can be detected by reverse transcriptase polymerase chain reaction (RT-PCR) or fluorescence in situ hybridization (FISH). Most cases affecting children and young adults seem to be indolent, but some adult cases have presented with metastasis or caused death. As previously reported cases remain limited to date, further examination in a large scale study will be needed in order to elucidate clinical behavior and molecular characteristics.

Multinodular and Vacuolating Neuronal Tumors of the Cerebrum: 10 Cases of a Distinctive Seizure‐Associated Lesion

We report 10 cases of a non-neurocytic, purely neuronal tumor affecting adults. Situated in the cerebral hemispheres, with 7 of 10 confined to the temporal lobes, most presented with seizures as their principal clinical manifestations. On magnetic resosnance imaging (MRI), the tumors generally appeared solid and non-contrast enhancing with minimal diffuse infiltration, edema, or mass effect. Six examples demonstrated internal nodularity. Microscopically, the tumor cells were largely distributed into discrete and coalescent nodules exhibiting varying degrees of matrix vacuolization, principally within the deep cortical ribbon and superficial subcortical white matter. Populating elements ranged from morphologically ambiguous to recognizably neuronal, with only two cases manifesting overt ganglion cell cytology. In all cases, tumor cells exhibited widespread nuclear immunolabeling for the HuC/HuD neuronal antigens, although expression of other neuronal markers, including synaptophysin, neurofilament and chromogranin was variable to absent. Tumor cells also failed to express GFAP, p53, IDH1 R132H, or CD34, although CD34-labeling ramified neural elements were present in the adjoining cortex of seven cases. Molecular analysis in a subset of cases failed to reveal DNA copy number abnormalities or BRAF V600E mutation. Follow-up data indicate that this unusual neuronal lesion behaves in benign, World Health Organization (WHO) grade I fashion and is amenable to surgical control.

Histological and morphometric lesions in the pre-clinical, developmental phase of insulin-induced laminitis in Standardbred horses

Lamellar pathology in experimentally-induced equine laminitis associated with euglycaemic hyperinsulinaemia is substantial by the acute, clinical phase (∼48h post-induction). However, lamellar pathology of the developmental, pre-clinical phase requires evaluation. The aim of this study was to analyse lamellar lesions both qualitatively and quantitatively, 6, 12 and 24h after the commencement of hyperinsulinaemia. Histological and histomorphometrical analyses of lamellar pathology at each time-point included assessment of lamellar length and width, epidermal cell proliferation and death, basement membrane (BM) pathology and leucocyte infiltration. Archived lamellar tissue from control horses and those with acute, insulin-induced laminitis (48h) was also assessed for cellular proliferative activity by counting the number of cells showing positive nuclear immuno labelling for TPX2. Decreased secondary epidermal lamellar (SEL) width and increased histomorphological evidence of SEL epidermal basal (and supra-basal) cell death occurred early in disease progression (6h). Increased cellular proliferation in SELs, infiltration of the dermis with small numbers of leucocytes and BM damage occurred later (24 and 48h). Some lesions, such as narrowing of the SELs, were progressive over this time period (6-48h). Cellular pathology preceded leucocyte infiltration and BM pathology, indicating that the latter changes may be secondary or downstream events in hyperinsulinaemic laminitis.

A pilot study of the immunohistochemical pattern of neuropilin-2 (NRP2) labeling and correlation with tumor stage in colon cancer.

e14098 Background: Neuropilin 2 (NRP2) is a transmembrane glycoprotein, non-associated with kinase domains, implicated in neovascularization and metastasis of colon cancer. NRP2 has been proposed as a molecular marker for targeted cancer therapy based on its multiple functions in cancer promotion. NRP2 signaling pathway and its expression have been demonstrated in many carcinomas. To the best of our knowledge, no description of the immunohistochemical staining pattern of NRP2 in colon cancer has been published in the English medical literature. The aim of this study is to investigate the NRP2 labelilng pattern in colon cancer and correlate it with tumor stage. Methods: Tumor sections from 35 randomly selected colectomy specimens with colorectal cancer collected during the last three years were retrieved from the University of Toledo Medical Center Department of Pathology archival material. Formalin fixed, paraffin embedded, 4 μm tissue sections containing invasive tumor were immunolabeled with a commercial antibody against NRP2, using a Ventana Benchmark LT automated instrument. Randomized, immunolabeled colon cancer tissue sections were blindly reviewed by two pathologists. Cytoplasmic and nuclear expression of NRP2 by tumor cells was graded as negative (no staining), focal (staining in <50% of cells), and diffuse (staining in ≥ 50% of cells). Adjacent benign colonic mucosa was used as an internal control. Results: No T1 or T2 tumor displayed diffuse nuclear labeling for the NRP2 epitope. In contrast, 13/20 T3 tumors (65%) and 4/4 T4 tumors (100%) displayed diffuse nuclear labeling. The association of diffuse nuclear NRP2 labeling with tumor grade was highly statistically significant (p=0.0055 by Chi-squared test). In contrast to nuclear labeling, cytoplasmic staining was observed in all stages and varied from negative to diffuse, but demonstrated no significant correlation with stage. Conclusions: This pilot study on colon cancer specimens suggests that diffuse nuclear immunolabeling of neuropilin-2 is indicative of a higher tumor stage. This finding suggests a potential use for this marker as a prognostic indicator for colon cancer in small biopsy samples.

Molecular mechanism of cell proliferation in rodent uterus during the estrous cycle

The rodent uterus is a widely studied target tissue for sexual steroid hormone action. The aim of the present study was to assess the molecular mechanism that participates in the initiation of cell proliferation of the rat uterine epithelial cells during the estrus (E)–metestrus (M) transition. Cell proliferation, ERα, c-fos, cyclin D1 and D3, cdk4, and cdk6 proteins were assessed in these animals by immunohistochemistry. Estradiol (E 2) and progesterone (P 4) plasma levels were assessed by RIA. The results indicate that the glandular epithelium starts to proliferate at 21:00 h on estrus day, and initiates at least 3 h before the luminal epithelium does. Fos expression was markedly increased during the afternoon of estrus day, and its increase was in parallel to ERα expression. Interestingly, both, cyclin D1 and D3 were abundantly expressed in the luminal and glandular epithelia, and nuclear immunolabelling of cyclin D1 and D3 precedes BrdU incorporation in the cell. cdk4 and cdk6 were localized in the nuclei in both epithelia throughout the studied time course. In addition, cdk4 was more abundant throughout estrus and metestrus days than cdk6. The overall results indicate that ERα, Fos and cyclins D1 and D3, cdk4 and cdk6 are expressed in both glandular and luminal epithelia of the rat uterus during the E–M transition. In conclusion, there is a good correlation between sequential expression of these proteins and cell cycle progression in the rat uterine epithelial cells during the estrous cycle. However, the differences observed in the cellular localization, time course of expression and the cellular types that express both cyclins between physiological and pharmacological conditions, demonstrated different mechanisms of regulation and should be due to the complex hormonal milieu during the estrous cycle.

Glioneuronal tumor with neuropil‐like islands: A new entity

Glioneuronal tumor with neuropil-like islands (GTNI) is a distinctive and rare tumor characterized by both glial and neuronal differentiation. However, unlike other mixed glioneuronal tumors, which are characterized by a favorable prognosis, this neoplasm has been found to be potentially aggressive. We report here a case arising in a 60-year old male patient who presented with seizures, forgetfulness and right-sided hemiparesis, due to a left frontal lobe tumor. Unlike most cases described in the literature, the present tumor was unique in its radiological appearance, which was cystic. On microscopic evaluation, the glial component was chiefly gemistocytic punctuated by neuropil-like islands. Strong nuclear immunolabeling of p53 and absence of 1p/19q deletion by fluorescence in situ hybridization assay were consistent with those in previous reports.

Temporal pleomorphic xanthoastrocytoma with glycogen accumulation – case report

Pleomorphic xanthoastrocytoma (PXA) is a rare superficial glioma that predominates in the young and has good prognosis. A long history of repeated seizures is commonly associated with PXA, which is frequently observed in neuroimaging scans as a solid-cystic, contrast-enhancing lesion. We report a case in which PXA diagnosis was favored by its histological features, such as pleomorphic multinucleated giant cells, with disproportionately few mitoses and necrotic areas. An eye-catching feature was widespread, pale-staining, circumscribed deposits in the cytoplasm of tumor cells, which turned out to be glycogen upon histochemical and electron-microscopical examination. The stored material was strongly PAS-positive and digested by diastase, and had a finely granular ultrastructural appearance. No evidence of lipid droplets was found on oil-red-O staining. The tumor was immunoreactive for glial fibrillary acidic protein and vimentin. Many cells were positive for CD34 on the external membrane, a feature which has been described in chronic CNS lesions associated with epilepsy. Intracytoplasmic immunostaining for EGFR was observed in most tumor cells, which might have favored neoplastic proliferation. Nuclear immunolabeling for p53 protein was rare and does not support a major role for p53 mutation in PXA tumorigenesis. Intracellular accumulation of glycogen in glial tumors is uncommon and may originate from abnormalities in carbohydrate metabolic pathways.

Expression of androgen receptor and 3β-hydroxysteroid dehydrogenase in corpora lutea during pregnancy in the rat

Immunoexpression of androgen receptor (AR) and 3beta-hydroxysteroid dehydrogenase (3beta-HSD) was investigated in three generations of corpora lutea (CLs), found in the ovaries of rats on Days 1, 2, 5, 9, 14 and 20 of pregnancy. The youngest generation of CLs functioned during the whole pregnancy, whereas the older and the oldest generations underwent earlier regression. The newly formed CLs exhibited weak cytoplasmic 3beta-HSD expression. During subsequent days, a gradual increase in 3beta-HSD immunolabelling was observed, followed by a decrease on Day 20. In the older and the oldest CLs, surviving luteal cells demonstrated strong, although in the oldest CLs mostly perinuclear, 3beta-HSD immunoreaction. The newly formed CLs showed weak nuclear AR immunolabelling, which became stronger during the following days. On Day 20, luteal cells demonstrated a weaker nuclear immunoreaction. The older and oldest generations of CLs exhibited weaker and almost negative AR immunolabelling, respectively. Of special interest was the richly vascularised apical region of young CLs. Here luteal cells with more intensive 3beta-HSD staining predominated, whereas cytoplasmic AR immunoreaction was accompanied by positive or negative nuclear AR immunoexpression. The present studies showed differences in AR and 3beta-HSD distribution within various generations of CLs and within particular regions of the same young CL.

Transitional Cell Carcinoma in Fishing Cats (Prionailurus viverrinus): Pathology and Expression of Cyclooxygenase-1, -2, and p53

A high prevalence of urinary bladder transitional-cell carcinoma (TCC) has been noted in captive fishing cats (Prionailurus viverrinus). Of the 91 adult deaths between 1995 and 2004, 12 (13%) were attributed to TCC. To help elucidate mechanisms of carcinogenesis, archival sections of urinary bladder from 14 fishing cats were examined histologically and immunohistochemically for p53, cyclooxygenase (COX)-1, and COX-2 expression. Ten cats had TCC, and 4 were unaffected. The average age at death was 10.8 years in affected individuals and 10.5 years in unaffected individuals. There was no sex predilection. Fishing cat TCCs were characterized histologically as papillary and infiltrating (n = 6), nonpapillary and infiltrating (n = 3), or carcinoma in situ (n = 1). Glandular and squamous metaplasia, necrosis, and lymphatic invasion were prominent histologic features. Two individuals had documented metastasis. p53 nuclear immunolabeling was detected in 4/10 (40%) TCCs. In two cases, immunolabeling was limited to less than 10% of the neoplastic cellular population and was comparable to staining of normal fishing cat bladder. Therefore, p53 gene mutation did not appear to be an essential component of TCC carcinogenesis in examined fishing cats. COX-1 immunohistochemistry was negative in all cases. All TCCs had some degree of COX-2 cytoplasmic immunolabeling, which was exclusively within the invasive portions of the neoplasms. Papillary portions were uniformly negative. COX-2 overexpression was a prominent feature in the majority of the examined fishing cat TCCs, suggesting that COX-2-mediated mechanisms of carcinogenesis are important in this species and that COX-inhibiting drugs may be of therapeutic benefit.