Comparison between the Mission Plus device and gold standard methods for measuring hemoglobin concentrations and packed cell volumes in cattle.

BACKGROUND: A point-of-care device that can provide immediate and reliable hemoglobin (Hb) concentrations and packed cell volumes (PCVs) would be useful in veterinary medicine. OBJECTIVES: We aimed to compare the use of a human device (Mission Plus; MP) with a gold standard (GS) method for measuring Hb concentrations and PCVs in cattle blood. METHODS: Blood samples from clinically healthy cattle (n = 122) were collected with or without an anticoagulant (K2 EDTA). The GS and MP methods were compared with correlation coefficients. Passing-Bablok regression analyses were also performed, and the acceptability judgment was completed using Bland-Altman plots. RESULTS: The CVmax for Hb values obtained using the GS method, the MP device without K2 EDTA, and the MP device with K2 EDTA were approximately 2.70%, 1.70%, and 2.0%, respectively, whereas the CVmax for PCVs was 0.90%, 1.83%, and 2.05%, respectively. A positive correlation (97.5% confidence interval) was observed between the Hb concentrations and PCV values detected using the MP and GS techniques in blood with and without K2 EDTA. Bland-Altman plots showed agreement between the MP and GS methods. For Hb using blood collected with or without the addition of K2 EDTA, the mean differences were -0.87 g/dL (95% CI: 1.35; -3.96) and 0.08 g/dL (95% CI: 2.16, -1.99), respectively. For PCVs using blood collected with or without the addition of K2 EDTA, the mean differences were -3.75% (95% CI: 0.61. -8.12) and -0.88% (95% CI: 2.86, -4.62), respectively. CONCLUSIONS: The MP device can be used to analyze Hb concentrations and PCVs in bovine blood to assist in field diagnoses.

Critical assessment of enhancement factor measurements in surface-enhanced Raman scattering on different substrates.

The SERS enhancement factor (SERS-EF) is one of the most important parameters that characterizes the ability of a given substrate to enhance the Raman signal for SERS applications. The comparison of SERS intensities and SERS-EF values across different substrates is a common practice to unravel the performance of a given substrate. In this study, it is shown that such a comparison may lack significance if we compare substrates of very distinct nature and optical properties. It is specifically shown that the SERS-EF values for static substrates (e.g. immobilized metallic nanostructures) cannot be compared to those of dynamic ones (e.g. colloidal metal nanoparticle solutions), and that the optical properties for the latter show strong dependence on the metal-molecule interaction dynamics. The most representative experimental results concerning the dynamic substrates have been supported by generalized Mie theory simulations, which are tools used to describe the substrate complexity and the microscopic information not usually taken into account.