Comparison of the Potential Abilities of Three Spectroscopy Methods: Near-Infrared, Mid-Infrared, and Molecular Fluorescence, to Predict Carotenoid, Vitamin and Fatty Acid Contents in Cow Milk

The objective of this work is to compare the ability of three spectroscopy techniques: molecular fluorescence, near-infrared (NIR), and mid-infrared with attenuated total reflectance (MIR-ATR) spectroscopy to predict the concentrations of 8 carotenoids, 6 vitamins and 22 fatty acids (FA) in cow’s milk. A dataset was built through the analysis of 242 frozen milk samples from different experiments. The milk compounds were analysed using reference methods and by NIR, MIR-ATR, and fluorescence to establish different predictive models. NIR spectroscopy allowed for better prediction of cis9-β-carotene, β-cryptoxanthin and the sum of carotenoids than the other techniques, with a coefficient of cross-validation in calibration (R²CV) > 0.60 and a coefficient of determination in validation (R²V) > 0.50. Their standard errors of prediction (SEP) were equal to 0.01, except for the sum of carotenoids (SEP = 0.15). However, MIR-ATR and fluorescence seem usable for the prediction of lutein and all-trans-β-carotene, respectively. These three spectroscopy methods did not allow us to predict (R²CV < 0.30) vitamin contents except, for vitamin A (the best R²CV = 0.65 with NIR and SEP = 0.15) and α-tocopherol (the best R²CV = 0.56 with MIR-ATR and SEP = 0.41), but all R²V were <0.30. NIR spectroscopy yielded the best prediction of the selected milk FA.

Effects of Azgp1-/-on mammary gland, adipose tissue and liver gene expression and milk lipid composition in lactating mice

The expression of Azgp1 gene, an adipokine involved in the mobilization of body reserves, was observed in mammary gland of ruminants. Its regulation by different dietary conditions suggests a potential role in the mechanisms controlling the composition of milk fat. The aim of this study was to evaluate the role of Azgp1 during lactation. Azgp1^-/- mice were compared to wild-type to determine its effects on milk fatty acid composition and offspring growth. To determine its effects on mammary gland, adipose tissue and liver gene expression, gene expression was analyzed using RT-qPCR via TLDA analyses. The body weight of Azgp1^-/- mothers was slightly higher after parturition and at 10 days of lactation compared to the wild type. The milk polyunsaturated fatty acid content was increased in Azgp1^-/- mice. Among the 40 genes studied, Azgp1^-/- modified the expression of 9, 10 and 3 genes in mammary gland, adipose tissue and liver, respectively. These genes, involved in fatty acid synthesis, transport and triglyceride synthesis, were downregulated in Azgp1^-/- mice showing a particularity during lactation. Changes in mammary gland gene expression may explain the modifications observed in milk fatty acid composition. This study supports a role of Azgp1 on lipid metabolism, in particular in mammary gland, during lactation function.

Serological determination of hepatitis C virus genotype: comparison with a standardized genotyping assay

In patients with chronic hepatitis C, determination of hepatitis C virus (HCV) genotype could be routinely run in the future to tailor treatment schedules. The suitabilities of two versions of a serological, so-called serotyping assay (Murex HCV Serotyping Assay version 1-3 [SA1-3] and Murex HCV Serotyping Assay version 1-6 [SA1-6]; Murex Diagnostics Ltd.), based on the detection of genotype-specific antibodies directed to epitopes encoded by the NS4 region of the genome, for the routine determination of HCV genotypes were studied. The results were compared with those of a molecular biology-based genotyping method (HCV Line Probe Assay [INNO-LiPA HCV]; Innogenetics S.A.), based on hybridization of PCR products onto genotype-specific probes designed in the 5' noncoding region of the genome, obtained with pretreatment serum samples from 88 patients with chronic hepatitis C eligible for interferon therapy. Definitive genotyping was performed by sequence analysis of three regions of the viral genome in all samples with discrepant typing results found among at least two of the three assays studied. In all instances, sequence analysis confirmed the result of the INNO-LiPA HCV test. The sensitivity of SA1-3 was 75% relative to the results obtained by the genotyping assay. The results were concordant with those of genotyping for 92% of the samples typeable by SA1-3. The sensitivity of SA1-6 was 89% relative to the results obtained by the genotyping assay. The results were concordant with those of genotyping for 94% of the samples typeable by SA1-6. Overall, SA1-6 had increased sensitivity relative to SA1-3 but remained less sensitive than the genotyping assay on the basis of PCR amplification of HCV RNA. Cross-reactivities between different HCV genotypes could be responsible for the mistyping of 8 (SA1-3) and 6% (SA1-6) of the samples. Subtyping of 1a and 1b is still not possible with the existing peptides, but discriminating between subtypes may not be necessary for routine use.