Human adenovirus type 36 enhances glucose uptake in diabetic and nondiabetic human skeletal muscle cells independent of insulin signaling

OBJECTIVE—Human adenovirus type 36 (Ad-36) increases adiposity but improves insulin sensitivity in experimentally infected animals. We determined the ability of Ad-36 to increase glucose uptake by human primary skeletal muscle (HSKM) cells.RESEARCH DESIGN AND METHODS—The effect of Ad-36 on glucose uptake and cell signaling was determined in HSKM cells obtained from type 2 diabetic and healthy lean subjects. Ad-2, another human adenovirus, was used as a negative control. Gene expression and proteins of GLUT1 and GLUT4 were measured by real-time PCR and Western blotting. Role of insulin and Ras signaling pathways was determined in Ad-36–infected HSKM cells.RESULTS—Ad-36 and Ad-2 infections were confirmed by the presence of respective viral mRNA and protein expressions. In a dose-dependent manner, Ad-36 significantly increased glucose uptake in diabetic and nondiabetic HSKM cells. Ad-36 increased gene expression and protein abundance of GLUT1 and GLUT4, GLUT4 translocation to plasma membrane, and phosphatidylinositol 3-kinase (PI 3-kinase) activity in an insulin-independent manner. In fact, Ad-36 decreased insulin receptor substrate-1 (IRS-1) tyrosine phosphorylation and IRS-1–and IRS-2–associated PI 3-kinase activities. On the other hand, Ad-36 increased Ras gene expression and protein abundance, and Ras siRNA abrogated Ad-36–induced PI 3-kinase activation, GLUT4 protein abundance, and glucose uptake. These effects were not observed with Ad-2 infection.CONCLUSIONS—Ad-36 infection increases glucose uptake in HSKM cells via Ras-activated PI 3-kinase pathway in an insulin-independent manner. These findings may provide impetus to exploit the role of Ad-36 proteins as novel therapeutic targets for improving glucose handling.Increasing prevalence of type 2 diabetes and insulin resistance is a major health and economic concern (1,2) and necessitates more effective prevention and treatment strategies. Intense search for identifying novel agents that may provide therapeutic targets for better management of diabetes is underway (3,4). Human adenovirus Ad-36 is such a novel candidate that increases adiposity but enhances insulin sensitivity in experimentally infected rats (5), an effect that is robust and reminiscent of the thiozolinediones (6,7). After a single inoculation of Ad-36, fat depot weight increased by >60%, but the fasting insulin levels and homeostasis model assessment (HOMA) index were ∼50% lower in rats up to 7 months later (5). Therefore, we postulated that Ad-36 increases glucose uptake in infected tissue, which may contribute in enhancing whole-body insulin sensitivity.This study investigated the ability of Ad-36 to enhance glucose uptake by skeletal muscle. Skeletal muscle is the largest organ of the human body and is a major site of glucose disposal and insulin action (8). Therefore, exploiting the ability of Ad-36 to enhance glucose uptake by skeletal muscle may provide a novel therapeutic target to treat glycemic disregulation in humans.In a stepwise approach, we investigated how Ad-36 influences the biomarkers of insulin sensitivity and glucose uptake. First, we determined whether Ad-36 increases glucose uptake in primary skeletal muscle cells from healthy lean and diabetic subjects. Next, the effect of Ad-36 on glucose transporters and their upstream cellular signaling, including phosphatidylinositol 3-kinase (PI 3-kinase) and its activators, was determined. Adenovirus type 2, a human adenovirus that is not adipogenic in animals (9), was used as a negative control. The following experiments showed that Ad-36 activates PI 3-kinase and increases glucose uptake in nondiabetic and diabetic human skeletal muscle (HSKM) cells. Activation of PI 3-kinase by Ad-36 requires Ras signaling but not insulin signaling pathway.     

Population pharmacokinetics of enfuvirtide in HIV-1-infected pediatric patients over 48 weeks of treatment

The objective of this study was to characterize the population pharmacokinetics of enfuvirtide in HIV-1-infected children and adolescents. HIV-infected patients received combination antiretroviral therapy, including enfuvirtide 2.0 mg/kg subcutaneously, twice daily. Serial and trough blood samples were collected up to 48 weeks. NONMEM was used for population pharmacokinetic analysis. Enfuvirtide exposure was calculated from individual parameter estimates derived from the final model. A total of 218 samples from 43 patients were included in the analysis. Enfuvirtide plasma concentration-time data were described by a 1-compartment model with first-order absorption and elimination. The addition of each subject's actual body weight as a covariate affected CL/F but not V/F or K(a). The population CL/F, V/F, and K(a) for a 33-kg reference patient was 1.31 L/h, 2.31 L, and 0.105 h(-1), respectively. The final model was CL/F (L/h) = 1.31 . (body weight/33 [kg])(0.721). Age did not affect enfuvirtide exposure. These results confirm the appropriateness of body weight-based pediatric enfuvirtide dosing.     

Microbes and obesity—interrelationship between infection,adipose tissue and the immune system

The world is currently experiencing an obesity epidemic as declared by the World Health Organization. The traditional view is that behaviour leading to overeating and under-activity is the major contributing factor for this worldwide epidemic. However, several microbes are linked to obesity in animals and humans. On the one hand, various microbes, including animal and human viruses, bacteria, parasites and scrapie agents, increase adiposity in several animal models. Some of these microbes show an association with human obesity, but conclusive evidence for a causative role of microbes in human obesity is lacking. On the other hand, obese individuals show an altered response to infections. Obesity is often associated with impaired immune function, which may lead to increased susceptibility to infection with a number of different pathogens. Hence, certain microbes appear to induce obesity, whereas, obesity itself may exacerbate certain other infections. Linking the two phenomenon is the immunological property of adipocytes and their progenitors. For instance, proliferating pre-adipocytes share embryonic origin with immune cells and exhibit phagocytic activity. Taken together it appears that there is a close interrelationship between adipose tissue, inflammatory response, immune system and infections. Hence, it is conceivable that in response to certain infections, adipose tissue expands similar to the expansion of cells of the immune system. The impaired immune function of adipose tissue in obesity may exacerbate infections. Considering the global obesity epidemic, it is necessary to further investigate both phenomena.     

Potential contributors to variation in weight-loss response to liraglutide

Obesity treatment requires a chronic state of negative energy balance. Obesity medications can help with this, increasing long-term dietary compliance by promoting satiety or reducing hunger. However, efficacy and safety of obesity medications vary for individuals. Early identification of non-responders to obesity medications may limit drug exposure while optimizing benefits for responders. This review summarizes factors that impact weight-loss response to liraglutide. Factors linked to greater weight loss on liraglutide include being female, not having diabetes, having relatively high baseline weight, and losing at least 4% of initial weight after 16 weeks of treatment. Other covariates that may predict treatment response but require further confirmation include central effects, nausea, gastric emptying of solids, and genotype. Baseline body mass index, race, and age seem less relevant for predicting weight-loss response to liraglutide. Lesser known and harder-to-measure factors such as cerebral blood flow, food cue reactivity, gut hormone levels, and dietary adherence possibly impact variability of response to liraglutide. This information should assist healthcare providers with establishing realistic weight-loss probability for individual patients. Future research should improve the ability to identify responders to liraglutide. Importantly, this review may provide a framework to identify responders to other obesity medications.     

NEW INVESTIGATOR AWARD FINALISTSNIA0001Induction of differentiation in human preadipocytes may contribute to adipogenic effect of human adenovirus Ad-36

Human adenovirus Ad-36 causes adiposity in animal models and shows association with human obesity. The mechanism involved is unknown. We previously reported that Ad-36 enhances differentiation of 3T3-L1 preadipocytes and E4orf-1 gene of the virus is responsible for the adipogenic effect in the rodent cell line. We undertook a three-step approach to investigate the role of preadipocyte differentiation in adipogenic effect of Ad-36. First, we showed that the viral mRNA is expressed in adipose-derived stem cells (ASC) of animals experimentally infected with Ad-36. Infection of rats with Ad-36 resulted in increased epididymal fat pad weight and the expression of Ad-36 E4orf-1 mRNA was detected in ASC isolated from the fat pads. Next, we determined if humans naturally infected with Ad-36 will show greater preadipocyte differentiation. Subcutaneous adipose-tissue samples from 33 Pima Indian subjects were screened by nested-PCR specific for Ad-36 DNA. Nine subjects (27%) had Ad-36 DNA. A blinded comparison of their ASC showed greater differentiation to adipocytes for the Ad-36 DNA positive subjects ( P =  0.06) compared to the Ad-36 DNA negative group. Finally, we used a direct approach. Human-ASC when infected with Ad-36 showed spontaneous replication, differentiation, and lipid accumulation, which was significantly greater than the uninfected controls ( P  < 0.01). Ad-36 induced lipid accumulation in human-ASC increased in response to the viral load and the lipogenic response was observed regardless of the donor gender and over an age range of 22–57 years. These results suggest that ability of Ad-36 to induce preadipocyte differentiation may play a role in human adiposity.     

高位胸段硬膜外麻醉下清醒病人的冠状动脉搭桥手术

目的　了解在高位胸段硬膜外麻醉下避免全麻行非体外循环心脏跳动下冠状动脉搭桥手术的可行性。方法　硬膜外麻醉下对 2 5例清醒病人行非体外循环心脏跳动下冠状动脉搭桥手术 ,没有气管插管全麻 ,所有病人在手术前晚行硬膜外置管。结果　总共搭桥 71支 (1支 11例 ,2支 5例 ,3支 6例 ,4支 3例 )。除 1例因为术中出现室颤转为全麻和体外循环外 ,2 4例在硬外麻作为唯一麻醉下完成非体外循环心脏跳动下冠状动脉搭桥手术。除 2例行左胸小切口外其余行正中切口 ;其中 6例为再次手术 ;平均每例搭桥2 8支 ,没有手术死亡。术后在复苏室和病房住院时间分别为 (16 2± 4 2 )h和 (3 2 4± 1 2 )d。结论　本组的早期经验提示在没有气管插管全麻、病人清醒下可以行多支冠状动脉搭桥术     

The Mitochondrial Genome And Human Mitochondrial Diseases

To date, more than 100 point mutations and several hundreds of structural rearrangements of mitochondrial DNA (mtDNA) are known too be connected with characteristic neuromuscular and other mitochondrial syndromes varying from those causing death at the neonatal stage to diseases with late ages of onset. The immediate cause of mitochondrial disorders is a defective oxidative phosphorylation. Wide phenotypic variation and the heteroplasmy phenomenon, which some authors include in mutation load, are characteristic of human mitochondrial diseases. As the numbers of cases identified and pedigrees described increase, data on the genotype-phenotype interaction and the structure and frequency of pathogenic and conditionally pathogenic mtDNA mutations in human populations are rapidly accumulated. The data on the genetics and epidemiology of mitochondrial diseases are not only important for differential diagnosis and genetic counseling. Since both neutral and mildly pathogenic mutations of mtDNA are progressively accumulated in maternal phyletic lines, molecular analysis of these mutations permits not only reconstruction of the genealogical tree of modern humans, but also estimation of the role that these mutations play in natural selection.