Point-of-care ß-hydroxybutyrate measurement for the diagnosis of feline diabetic ketoacidaemia.

OBJECTIVES: To evaluate accuracy and precision of a hand-held ketone meter measuring ß-hydroxybutyrate and to determine its diagnostic performance to rule out ketoacidaemia in diabetic cats. METHODS: The ketone meter was validated by calculating within-day precision at different ß-hydroxybutyrate concentrations and by comparison with a laboratory method. To determine its diagnostic performance to diagnose ketoacidaemia, 217 sets of data (venous blood gas analysis and ß-hydroxybutyrate measurements) were retrospectively analysed. Sensitivities and specificities were calculated with the help of receiver-operating characteristic curves. RESULTS: The ketone meter reliably detected ß-hydroxybutyrate at concentrations >0·1 mmol/L and reproducibility was acceptable. Measurements highly correlated with laboratory results (r=0·97; P<0·001), but a significant negative bias was found at high concentrations. A ß-hydroxybutyrate concentration of >2·55 mmol/L had a sensitivity of 94% and a specificity of 68% for diagnosing ketoacidaemia. Many cats with high ß-hydroxybutyrate concentrations and normal blood pH had an elevated chloride gap suggestive of superimposed hypochloraemic metabolic alkalosis. CLINICAL SIGNIFICANCE: The commercially available point-of-care ketone meter Precision Xtra is a valid tool to measure ß-hydroxybutyrate in diabetic cats. Concentration <2·55 mmol/L enable ketoacidaemia to be excluded and should lead to redirection of differential diagnoses.

Recombinant allergens promote expression of aminopeptidase-n (CD13) on basophils in allergic patients.

IgE-dependent activation of basophils is associated with upregulation of several surface molecules. We recently identified the surface enzyme aminopeptidase N (CD13) as a novel activation antigen on human basophils. In the present study, we asked whether CD13 can be employed as a novel marker of allergen-induced activation of basophils in allergic individuals. Patients allergic to major allergens from grass pollen (Phl p 1, Phl p 5), birch pollen (Bet v 1), or house dust mites (Der p 2), were examined. Blood basophils were exposed to various concentrations of recombinant allergens for 15 minutes, and examined for expression of CD13 by multicolor flow cytometry. The allergen-induced upregulation of CD13 was compared with allergen-dependent increases in expression of CD63 and CD203c. Exposure to recombinant allergens resulted in an increase in expression of CD13 on basophils in all sensitized individuals, whereas no increase in CD13 was seen in healthy controls. The effects of the recombinant allergens on CD13-expression were dose- and time-dependent, were not observed in the absence of extracellular calcium, and were counteracted by preincubation of basophils with the PI3-kinase-targeting drugs staurosporin and LY294002. There was a good correlation between allergen-induced upregulation of CD13, CD63, and CD203c on basophils. In aggregate, our data show that recombinant allergens promote expression of CD13 on basophils in sensitized individuals. The functional significance and diagnostic implications of this observation remain to be determined.