No evidence for tumorigenesis of AAV vectors in a large-scale study in mice.

Six hundred ninety-five mice received adeno-associated virus (AAV) vectors, mostly via portal vein injection. At necropsy, the livers were inspected for tumors, and tissue sections were prepared for histology. We observed only one tumor, a lipoma, resulting in a tumor frequency of 0.14%. This tumor contained fewer vector genomes per total DNA than the surrounding liver tissue, as shown by quantitative PCR. In another mouse we found a macroscopically visible nodule containing lymphocytes. Immunohistochemistry revealed cells not of monoclonal origin, and they contained fewer AAV genomes than the surrounding hepatocytes. There were no macroscopic tumors in 226 control mice. Upon microscopic examination, lymphocytic infiltrates were found in 5% of livers of both control and vector-treated mice; no transgene expression was seen in those infiltrates in AAV-injected animals. Compared to an average frequency of spontaneous liver tumors in C57BL/6 mice (0-10%), and given the absence of high levels of vector DNA in the observed tumor, we conclude that AAV vectors do not predispose these target animals to the formation of liver tumors.     

Detecting Selection in the HIV-1 Genome during Sexual Transmission Events

Little is known about whether and how variation in the HIV-1 genome affects its transmissibility. Assessing which genomic features of HIV-1 are under positive or negative selection during transmission is challenging, because very few virus particles are typically transmitted, and random genetic drift can dilute genetic signals in the recipient virus population. We analyzed 30 transmitter–recipient pairs from the Zurich Primary HIV Infection Study and the Swiss HIV Cohort Study using near full-length HIV-1 genomes. We developed a new statistical test to detect selection during transmission, called Selection Test in Transmission (SeTesT), based on comparing the transmitter and recipient virus population and accounting for the transmission bottleneck. We performed extensive simulations and found that sensitivity of detecting selection during transmission is limited by the strong population bottleneck of few transmitted virions. When pooling individual test results across patients, we found two candidate HIV-1 genomic features for affecting transmission, namely amino acid positions 3 and 18 of Vpu, which were significant before but not after correction for multiple testing. In summary, SeTesT provides a general framework for detecting selection based on genomic sequencing data of transmitted viruses. Our study shows that a higher number of transmitter–recipient pairs is required to improve sensitivity of detecting selection.     

Empagliflozin Improves Insulin Sensitivity of the Hypothalamus in Humans With Prediabetes: A Randomized,Double-Blind,Placebo-Controlled,Phase 2 Trial

OBJECTIVEInsulin action in the human brain reduces food intake, improves whole-body insulin sensitivity, and modulates body fat mass and its distribution. Obesity and type 2 diabetes are often associated with brain insulin resistance, resulting in impaired brain-derived modulation of peripheral metabolism. So far, no pharmacological treatment for brain insulin resistance has been established. Since sodium–glucose cotransporter 2 (SGLT2) inhibitors lower glucose levels and modulate energy metabolism, we hypothesized that SGLT2 inhibition may be a pharmacological approach to reverse brain insulin resistance.RESEARCH DESIGN AND METHODSIn this randomized, double-blind, placebo-controlled clinical trial, 40 patients (mean ± SD; age 60 ± 9 years; BMI 31.5 ± 3.8 kg/m²) with prediabetes were randomized to receive 25 mg empagliflozin every day or placebo. Before and after 8 weeks of treatment, brain insulin sensitivity was assessed by functional MRI combined with intranasal administration of insulin to the brain.RESULTSWe identified a significant interaction between time and treatment in the hypothalamic response to insulin. Post hoc analyses revealed that only empagliflozin-treated patients experienced increased hypothalamic insulin responsiveness. Hypothalamic insulin action significantly mediated the empagliflozin-induced decrease in fasting glucose and liver fat.CONCLUSIONSOur results corroborate insulin resistance of the hypothalamus in humans with prediabetes. Treatment with empagliflozin for 8 weeks was able to restore hypothalamic insulin sensitivity, a favorable response that could contribute to the beneficial effects of SGLT2 inhibitors. Our findings position SGLT2 inhibition as the first pharmacological approach to reverse brain insulin resistance, with potential benefits for adiposity and whole-body metabolism.     

Assignment test method using hypervariable markers for blue marlin (Makaira nigricans) stock identification

Blue marlin (Makaira nigricans) stock status varies among ocean basins, and the Atlantic-wide stock is overfished. United States regulations prohibit commercial landing, importation and sale of Atlantic blue marlin, but not of Pacific or Indian Ocean conspecifics. We genotyped 344 blue marlin of known origin and 16 samples used as unknowns at 13 microsatellite loci and the mitochondrial control region. Assignment tests were conducted using GENECLASS2 to investigate the efficacy of available genotypic data to identify individual origin. We successfully discriminated Atlantic and Pacific blue marlin using genetic characters, providing more power to assign marketed blue marlin products to ocean of origin.