Plasma lipoprotein concentrations in ethnic populations

Apolipoprotein CIII Reduction Protects White Adipose Tissues against Obesity-Induced Inflammation and Insulin Resistance in Mice

Apolipoprotein CIII (apoCIII) is proinflammatory and increases in high-fat diet (HFD)-induced obesity and insulin resistance. We have previously shown that reducing apoCIII improves insulin sensitivity in vivo by complex mechanisms involving liver and brown adipose tissue. In this study the focus was on subcutaneous (SAT) and visceral (VAT) white adipose tissue (WAT). Mice were either given HFD for 14 weeks and directly from start also treated with antisense oligonucleotide (ASO) against apoCIII or given HFD for 10 weeks and HFD+ASO for an additional 14 weeks. Both groups had animals treated with inactive (Scr) ASO as controls and in parallel chow-fed mice were injected with saline. Preventing an increase or lowering apoCIII in the HFD-fed mice decreased adipocytes’ size, reduced expression of inflammatory cytokines and increased expression of genes related to thermogenesis and beiging. Isolated adipocytes from both VAT and SAT from the ASO-treated mice had normal insulin-induced inhibition of lipolysis compared to cells from Scr-treated mice. In conclusion, the HFD-induced metabolic derangements in WATs can be prevented and reversed by lowering apoCIII.

Tacrolimus pharmacokinetics in Hispanic children after kidney transplantation

Ethnic differences in drug pharmacokinetics are well recognized including that for tacrolimus (TAC) in adult subjects. However, similar knowledge among pediatric populations is missing. Our limited retrospective study compares steady-state pharmacokinetics of TAC in Hispanic versus non-Hispanic children. Serial blood samples were collected and whole blood concentrations of TAC were measured using radioimmunoassay. Compared with non-Hispanic children, Hispanic children had lower measures of drug exposure (maximum drug concentration [Cmax] and area under the drug concentration-time curve [AUC0-∞]), higher volume of distribution, and faster clearance. Interestingly, only in Hispanic children, significant correlations were found between body weight and clearance, age and volume of distribution, and Schwartz estimated glomerular filtration rate and half-life. In conclusion, our study suggests that ethnic differences exist between Hispanic and non-Hispanic children in TAC PK, and based on our preliminary findings, either a higher or more frequent TAC dosing may be required for effective immunosuppression therapy in Hispanic children.

False-positive results in neonatal screening for cystic fibrosis based on a three-stage protocol (IRT/DNA/IRT): Should we adjust IRT cut-off to ethnic origin?

Since 1979, newborn screening for cystic fibrosis (CF) has been possible by measuring immunoreactive tryspinogen (IRT) in blood spots. In France, a programme based on a three-stage strategy (IRT/DNA/IRT) started in 2002. In the Rhône-Alpes area, the positive screening rate (i.e. the proportion of samples sent for genotyping) observed after the first IRT measurement was higher than the expected rate (0.65% versus 0.50%), without a greater CF incidence. We hypothesized that the IRT reference range could differ according to the ethnic origin of the newborns. 35 141 newborns were studied and divided into two groups: European ethnic group 26 324 (75%) and North African ethnic group 8817 (25%). 243 positive newborns were identified: 146 (60%) in the European ethnic group and 97 (40%) in the North African ethnic group. Three CF patients and 11 unaffected heterozygotes were found in the European group, but no mutations were found in the North African group. Mean IRT values and the percentage of IRT values over the cut-off were significantly higher in the North African group than in the European group (mean IRT = 21.17 microg/L and 19.74 microg/L, p < 0.0001; %IRT > cut-off = 1.1% and 0.5%, respectively). For the positive screened newborns, term and IRT mean were comparable, whereas birth weight was higher in the North African ethnic group. These results lead us to conclude that (i) newborns from families of North African origin have higher IRT values and (ii) most of the positive screened newborns in this population could be considered as 'false positives'. These conclusions could explain, in part, the large variations seen in the positive screening rate in the French CF neonatal screening and raise the question whether it is relevant to adapt cut-off to ethnic origin of the newborns.