Gap junctions and communication within the nervous system

Gap junctions are sites on the cellular membrane with intercellular channels build up by twelve protein subunits called connexins. Each connected cell contributes with a hemichannel made up by six connexins subunits. This kind of connection represents and efficient way of intercellular communication in most tissues, including the nervous system. It works as a passage for ions, secondary messenger and metabolites exchange between the cells. In a complex tissue like the nervous tissue they are particularly important because they connect the various cellular types composing a panglial syncytium that performs neuronal protection and tissue homeostasis. The expression of connexins and the intercellular communication through gap junctions are crucial to regulate vital functions as cellular motility, proliferations and survival; changes in the conformational expression of connexins may be involved in diseases as Alzheimer´s disease, neoplasms, bacterial and parasitic infections, or even affect cellular groups when they occur as genetic mutations leading to functional defects of the nervous system as demyelination in the PNS (Charcot-Marie-Tooth disease), hereditary epilepsy, nonsyndromic deafness and senile cataract.

Morphology and immunophenotypes of canine lymphomas: a survey from the service of animal pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, Brazil

Lymphoma is a malignant clonal expansion of lymphoid cells, and is reported to be one of the most common hematopoietic neoplasms in dogs. The purpose of this study was to perform a survey of lymphomas diagnosed at the Service of Animal Pathology of the School of Veterinary Medicine and Animal Science, University of São Paulo, Brazil, from 1995 to 2009, and determine their morphological subtypes and immunophenotypes. Breed, age and gender were recorded. The canine lymphomas were classified according to the updated Kiel classification, and all the cases were submitted to immunostaining for CD3 and CD79a antibodies to reveal their T or B origin, respectively. In addition, mitotic figures were counted in all samples, in 10 microscopic fields. Mixed breed dogs were the most affected breed (43%), followed by Boxer (14%), German Shepherd (11%), Brazilian terrier (3%), Poodle (3%) and Rottweiler (3%). Other breeds were represented at a rate below 1%. Among the 65 cases of lymphomas, 30 cases were found in females and 35 in males. The mean age was 8.7 years with a range of 5 months to 15 years. The most frequent localization was multicentric lymphadenopathy (37%), followed by extranodal (23%), cutaneous (20%), alimentary tract (18%) and mediastinal site (2%). From 65 canine lymphomas, 55 (85%) had T-cell origin and 10 (15%) had B-cell origin. Among mitotic index, 51% (n=33) of T-cell or

Canine hemangiopericytomas: cell proliferation and apoptosis in the perivascular, storiform and epithelioid histological subtypes and their significance for prognosis

Canine hemangiopericytomas (CHP) are soft tissue neoplasms, originary from pericytes. They are frequently diagnosed in dogs and can be seen more frequently in limbs as circumscribed and firm nodules. The histopathology of CHP reveals the presence of spindle cells around blood vessels, forming whorls. In this study, cases of CHP from the Animal Pathology Service of the Veterinary Hospital of the School of Veterinary Medicine and Animal Science, registered from 1990 to 2003, were studied. All cases were reviewed and classified in the three histological subtypes recently described perivascular (PVHP), storiform (SHP) and epithelioid (EHP). Immunohistochemical markers (vimentin, S-100 protein, CD34, Factor VIII and glial fibrillary acidic protein GFAP) were applied to all tumors. Samples were submitted to the immunostaining of PCNA, and the labeling indexes were obtained. The mitotic index was also quantified in each subtype. Apoptosis bodies were morphologically identified in H&E stained sections, subsequently confirmed by fluorescence microscopy and then quantified in the three histological subtypes. Dog owners were contacted by telephone, and asked to inform about the outcome of their dogs. The survey revealed 61 cases of CHP, in which 21 (34.43.%) belonged to the perivascular subtype, 18 cases (29.51.%) belonged to the storiform subtype, and 22 cases (36.06.%) belonged

Compensatory kidney hypertrophy/hyperplasia after nephrectomy in mice: alterations of connexin 43 (Cx43) phosphorylated isoforms

Compensatory kidney hypertrophy/hyperplasia leads to several changes in kidney structure and function, as increased glomeruli filtration. The aim of this study was to evaluate connexin 43 in remnant mouse kidneys after unilateral nephrectomy. The right kidney was surgically removed from BALB/c mice. Groups were euthanized at 24, 48 and 72 hours, and at 7 and 30 days. Kidney sections of the reminiscent kidneys were stained with Periodic Acid/Schiff and additional slides were submitted to BrdU and Cx43 immunohistochemistry. The results demonstrated an increase in kidney weight as early as 24 hours through 30 post-nephrectomy. In addition, BrdU positive epithelial cells increased at 24 and 48 hours post-nephrectomy. Cx43 was detected in the cytoplasm and membrane of epithelial cells and vasculature. Taking into consideration the quantity, intensity and localization of Cx43 immunostaining pattern, we observed that nephrectomized mice presented lower Cx43 expression and a cytoplasmic localization after 24 hours, peaking in 48 hours. Furthermore, western blot revealed that during the first 24 and 48 hours after nephrectomy, P0 (unphosphorylated) and P1 (phosphorylated) Cx43 disappeared, and the products of Cx43 degradation were reduced. On the other hand, after 72 hours the P0 and P1 state reappeared and the amount of degraded peptides also increased. Seven and thirty days after neph

Consensus for the diagnosis, prognosis and treatment of canine mammary tumors

The purpose of this paper is to establish criteria that could guide the diagnosis, prognosis and treatment of canine mammary neoplasias. It was elaborated during the Mammary Pathology Meeting: Diagnosis, Prognosis and Treatment of the Canine Mammary Neoplasm, held on November 6th and 7th, 2010 in Belo Horizonte MG, Brazil, sponsored by the Laboratory of Comparative Pathology UFMG, with the support of the Brazilian Association of Veterinary Pathology (ABPV) and Brazilian Association of Veterinary Oncology (ABROVET). Academics from several regions of Brazil were present and contributed to this work.