Deletion of individual Ku subunits in mice causes an NHEJ-independent phenotype potentially by altering apurinic/apyrimidinic site repair

Ku70 and Ku80 form a heterodimer called Ku that forms a holoenzyme with DNA dependent-protein kinase catalytic subunit (DNA-PKCS) to repair DNA double strand breaks (DSBs) through the nonhomologous end joining (NHEJ) pathway. As expected mutating these genes in mice caused a similar DSB repair-defective phenotype. However, ku70-/- cells and ku80 -/- cells also appeared to have a defect in base excision repair (BER). BER corrects base lesions, apurinic/apyrimidinic (AP) sites and single stand breaks (SSBs) utilizing a variety of proteins including glycosylases, AP endonuclease 1 (APE1) and DNA Polymerase β (Pol β). In addition, deleting Ku70 was not equivalent to deleting Ku80 in cells and mice. Therefore, we hypothesized that free Ku70 (not bound to Ku80) and/or free Ku80 (not bound to Ku70) possessed activity that influenced BER. To further test this hypothesis we performed two general sets of experiments. The first set showed that deleting either Ku70 or Ku80 caused an NHEJ-independent defect. We found ku80-/- mice had a shorter life span than dna-pkcs-/- mice demonstrating a phenotype that was greater than deleting the holoenzyme. We also found Ku70-deletion induced a p53 response that reduced the level of small mutations in the brain suggesting defective BER. We further confirmed that Ku80-deletion impaired BER via a mechanism that was not epistatic to Pol β. The second set of experiments showed that free Ku70 and free Ku80 could influence BER. We observed that deletion of either Ku70 or Ku80, but not both, increased sensitivity of cells to CRT0044876 (CRT), an agent that interferes with APE1. In addition, free Ku70 and free Ku80 bound to AP sites and in the case of Ku70 inhibited APE1 activity. These observations support a novel role for free Ku70 and free Ku80 in altering BER. © 2014 Choi et al

A randomized, controlled trial of 3.0 mg of liraglutide in weight management

BACKGROUND Obesity is a chronic disease with serious health consequences, but weight loss is difficult to maintain through lifestyle intervention alone. Liraglutide, a glucagonlike peptide-1 analogue, has been shown to have potential benefit for weight management at a once-daily dose of 3.0 mg, injected subcutaneously. METHODS We conducted a 56-week, double-blind trial involving 3731 patients who did not have type 2 diabetes and who had a body-mass index (BMI; the weight in kilograms divided by the square of the height in meters) of at least 30 or a BMI of at least 27 if they had treated or untreated dyslipidemia or hypertension. We randomly assigned patients in a 2:1 ratio to receive once-daily subcutaneous injections of liraglutide at a dose of 3.0 mg (2487 patients) or placebo (1244 patients); both groups received counseling on lifestyle modification. The coprimary end points were the change in body weight and the proportions of patients losing at least 5% and more than 10% of their initial body weight. RESULTS At baseline, the mean (±SD) age of the patients was 45.1±12.0 years, the mean weight was 106.2±21.4 kg, and the mean BMI was 38.3±6.4; a total of 78.5% of the patients were women and 61.2% had prediabetes. At week 56, patients in the liraglutide group had lost a mean of 8.4±7.3 kg of body weight, and those in the placebo group had lost a mean of 2.8±6.5 kg (a difference of -5.6 kg; 95% confidence interval, -6.0 to -5.1; P<0.001, with last-observation-carried-forward imputation). A total of 63.2% of the patients in the liraglutide group as compared with 27.1% in the placebo group lost at least 5% of their body weight (P<0.001), and 33.1% and 10.6%, respectively, lost more than 10% of their body weight (P<0.001). The most frequently reported adverse events with liraglutide were mild or moderate nausea and diarrhea. Serious events occurred in 6.2% of the patients in the liraglutide group and in 5.0% of the patients in the placebo group. CONCLUSIONS In this study, 3.0 mg of liraglutide, as an adjunct to diet and exercise, was associated with reduced body weight and improved metabolic control. (Funded by Novo Nordisk; SCALE Obesity and Prediabetes NN8022-1839 ClinicalTrials.gov number, NCT01272219.)

Cascade Impactor (CI) Mensuration—An Assessment of the Accuracy and Precision of Commercially Available Optical Measurement Systems

Multi-stage cascade impactors (CIs) are the preferred measurement technique for characterizing the aerodynamic particle size distribution of an inhalable aerosol. Stage mensuration is the recommended pharmacopeial method for monitoring CI “fitness for purpose” within a GxP environment. The Impactor Sub-Team of the European Pharmaceutical Aerosol Group has undertaken an inter-laboratory study to assess both the precision and accuracy of a range of makes and models of instruments currently used for optical inspection of impactor stages. Measurement of two Andersen 8-stage ‘non-viable’ cascade impactor “reference” stages that were representative of jet sizes for this instrument type (stages 2 and 7) confirmed that all instruments evaluated were capable of reproducible jet measurement, with the overall capability being within the current pharmacopeial stage specifications for both stages. In the assessment of absolute accuracy, small, but consistent differences (ca. 0.6% of the certified value) observed between ‘dots’ and ‘spots’ of a calibrated chromium-plated reticule were observed, most likely the result of treatment of partially lit pixels along the circumference of this calibration standard. Measurements of three certified ring gauges, the smallest having a nominal diameter of 1.0 mm, were consistent with the observation where treatment of partially illuminated pixels at the periphery of the projected image can result in undersizing. However, the bias was less than 1% of the certified diameter. The optical inspection instruments evaluated are fully capable of confirming cascade impactor suitability in accordance with pharmacopeial practice