Objective: To characterize the dynamics of calcitonin secretion in response to experimentally induced hypercalcemia in cats. Animals: 13 healthy adult European Shorthair cats. Procedures: For each cat, the calcitonin response to hypercalcemia (defined as an increase in ionized calcium concentration > 0.3 mM) was investigated by infusing calcium chloride solution and measuring circulating calcitonin concentrations before infusion (baseline) and at various ionized calcium concentrations. Calcitonin expression in the thyroid glands of 10 of the cats was investigated by immunohistochemical analysis. Results: Preinfusion baseline plasma calcitonin concentrations were very low in many cats, sometimes less than the limit of detection of the assay. Cats had a heterogeneous calcitonin response to hypercalcemia. Calcitonin concentrations only increased in response to hypercalcemia in 6 of 13 cats; in those cats, the increase in calcitonin concentration was quite variable. In cats that responded to hypercalcemia, calcitonin concentration increased from 1.3 ± 0.3 pg/mL at baseline ionized calcium concentration to a maximum of 21.2 ± 8.4 pg/mL at an ionized calcium concentration of 1.60 mM. Cats that did not respond to hypercalcemia had a flat calcitonin-to-ionized calcium concentration curve that was not modified by changes in ionized calcium concentration. A significant strong correlation (r = 0.813) was found between the number of calcitonin-positive cells in the thyroid gland and plasma calcitonin concentrations during hypercalcemia. Conclusions and clinical relevance: Healthy cats had very low baseline plasma calcitonin concentrations. A heterogeneous increase in plasma calcitonin concentration in response to hypercalcemia, which correlated with the expression of calcitonin-producing cells in the thyroid, was identified in cats.

<p>Isolados do vírus da diarreia viral bovina (BVDV) detectados em amostras de soro sanguíneo de dois animais persistentemente infectados (PI), identificados num rebanho bovino localizado na região sul do Estado de Minas Gerais, Brasil, foram submetidos à caracterização genética através do sequenciamento parcial de nucleotídeos da região 5’UTR do genoma viral. Os isolados foram caracterizados como pertencentes ao genótipo BVDV-1, subgenótipo BVDV-1b. Os resultados do presente estudo sugerem o BVDV-1b como um agente de importância na ocorrência da diarreia viral bovina (BVD) nos rebanhos da região. Ademais, a caracterização genotípica dos isolados do BVDV contribui para a melhor compreensão da epidemiologia da enfermidade, pois a variabilidade genética do BVDV interfere nos testes sorológicos e também possui implicações na utilização de vacinas, cuja maioria é produzida apenas com estirpes de referência do BVDV, requerendo, portanto, investigações sobre a diversidade genética do BVDV existente no Brasil para o aprimoramento das medidas de prevenção e controle da enfermidade no país.</p> | Isolates of bovine viral diarrhoea virus (BVDV) detected in serum samples of two persistently infected animals (PI) identified in a herd located in the southern state of Minas Gerais, Brazil, underwent genetic characterization trough partial nucleotide sequencing and analysis of the 5’ Untranslated Region (5’UTR) of the viral genome. The isolates were characterized as belonging to genotype BVDV-1, subgenotype BVDV-1b. The results of this study suggest BVDV-1b as an agent of importance in the occurrence of bovine viral diarrhoea (BVD) in the herds of the region. Moreover, the genotypic characterization of isolates of BVDV helps to better understand the epidemiology of the disease, as the genetic variability of BVDV interferes in the serological tests and has implications for the use of vaccines, whose majority is produced only with reference strains of BVDV. Therefore, the investigation on the genetic diversity of BVDV existing in Brazil is required for the improvement of the disease prevention and control measures

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