Polygenic Risk Scores for Prediction of Breast Cancer and Breast Cancer Subtypes

Stratification of women according to their risk of breast cancer based on polygenic risk scores (PRSs) could improve screening and prevention strategies. Our aim was to develop PRSs, optimized for prediction of estrogen receptor (ER)-specific disease, from the largest available genome-wide association dataset and to empirically validate the PRSs in prospective studies. The development dataset comprised 94,075 case subjects and 75,017 control subjects of European ancestry from 69 studies, divided into training and validation sets. Samples were genotyped using genome-wide arrays, and single-nucleotide polymorphisms (SNPs) were selected by stepwise regression or lasso penalized regression. The best performing PRSs were validated in an independent test set comprising 11,428 case subjects and 18,323 control subjects from 10 prospective studies and 190,040 women from UK Biobank (3,215 incident breast cancers). For the best PRSs (313 SNPs), the odds ratio for overall disease per 1 standard deviation in ten prospective studies was 1.61 (95%CI: 1.57-1.65) with area under receiver-operator curve (AUC) = 0.630 (95%CI: 0.628-0.651). The lifetime risk of overall breast cancer in the top centile of the PRSs was 32.6%. Compared with women in the middle quintile, those in the highest 1% of risk had 4.37- and 2.78-fold risks, and those in the lowest 1% of risk had 0.16- and 0.27-fold risks, of developing ER-positive and ER-negative disease, respectively. Goodness-of-fit tests indicated that this PRS was well calibrated and predicts disease risk accurately in the tails of the distribution. This PRS is a powerful and reliable predictor of breast cancer risk that may improve breast cancer prevention programs.NovartisEli Lilly and CompanyAstraZenecaAbbViePfizer UKCelgeneEisaiGenentechMerck Sharp and DohmeRocheCancer Research UKGovernment of CanadaArray BioPharmaGenome CanadaNational Institutes of HealthEuropean CommissionMinistère de l'Économie, de l’Innovation et des Exportations du QuébecSeventh Framework ProgrammeCanadian Institutes of Health Researc

Effect of paracetamol on mitochondrial membrane function in rat liver slices

The effect of paracetamol on mitochondrial function was studied using rat liver slices. Changes in the potential of the mitochondrial and plasma membrane were monitored using [3H]-triphenylmethylphosphonium (TPMP+) and [14C]thiocyanate (SCN-) probes, respectively. Liver slices were exposed to 10 mM paracetamol for various time periods (0-360 min) after loading with TPMP+. The release of TPMP+ which correlates with a decrease in the mitochondrial membrane potential became significant after 30 min incubation with 10 mM paracetamol. The change in the mitochondrial membrane potential was shown to be independent of cytochrome P450 activity. No significant change in plasma membrane potential was observed, until the release of lactate dehydrogenase (LDH) had begun, 4 hr after exposure, reflecting the ultimate stages of cell injury by paracetamol. These results suggest that paracetamol elicits a direct effect on the mitochondrial function before cell injury develops and adds further evidence to the role of mitochondria in paracetamol toxicity.</p

Salbutamol: tablets, inhalational powder, or nebuliser?

A study was carried out to ascertain the most effective method of giving salbutamol. Seventeen children with severe asthma received active salbutamol (4 mg via a nebuliser, 400 micrograms as an inhalational powder, or a 4 mg tablet) together with complementary placebos on a double-blind, triple-dummy randomly allocated basis. The bronchodilatation effect was assessed by measuring the peak expiratory flow rate. The bronchodilatation effect was greatest when patients received nebulised salbutamol (p less than 0.05) but lasted longest when they received the tablet (p less than 0.0001); the onset of the effect was rapid with all forms of administration. These results indicate that nebulised salbutamol gives the best relief in severe asthma; in less severe cases, however, a regimen combining the inhalational powder and tablets is sufficient and more convenient