Frequency of weight and body composition increases in advanced non-small cell lung cancer patients during first line therapy.

BACKGROUND: The primary objective of this study was to assess the frequency of body composition increases and their relationships to changes in body weight in two cohorts of real world, treatment-naïve, advanced non-small cell lung cancer (NSCLC) patients. One cohort received the current standard of care (CSOC), which consisted of immunotherapy and newer chemotherapy regimens, and the other cohort was treated with the former standard of care (FSOC), consisting only of older platinum-containing regimens. METHODS: CSOC (n = 106) and FSOC (n = 88) cohorts of advanced NSCLC patients were included in this study. Weights were collected at each clinical visit, and body composition analysis from routine chest computed tomography via automated segmentation software assessed at baseline and at 6 and 12 weeks. Standard statistical methods were used to calculate relationships between changes in weight and in body composition. RESULTS: The CSOC cohort contained 106 stage IV NSCLC patients treated between 16/12/2014 and 22/10/2020 while the FSOC cohort contained 88 stage III/IV NSCLC patients treated between 16/6/2006 and 18/11/2014. While each cohort exhibited decreases in median weight, body mass index (BMI), mean skeletal muscle index (SMI) and subcutaneous adipose tissue index (SATI) at the 6 and 12 week time points, a subset of patients experienced increases in these parameters. Using a threshold of ≥2.5% increase for weight, BMI, SMI, and SATI at the 12 week time point, both cohorts showed similar (20.5% and 27.3%) increases in these parameters. With a cut point of ≥5% increase at 12 weeks follow-up, 8.0% to 25.0% of the patients gained ≥5% in weight, BMI, SMI and SATI. Comparing these results in each cohort showed no significant differences. Pearson coefficients for weight change related to changes in SMI and SATI at 6 and 12 weeks ranged from 0.31 to 0.58 with all P values <0.02. Pearson coefficients for weight change at 12 weeks related to changes in VATI and IMATI ranged from 0.26 to 0.47 with all P values <0.05. Comparison of Pearson coefficients for each cohort showed no significant differences. CONCLUSIONS: Although decreases in median weight, BMI, SMI and SATI were observed in both cohorts, similar percentage of patients in each cohort experienced increases in these parameters. These findings, plus the positive correlations between longitudinal measurements of weight, muscle mass and adipose tissue, indicate that weight gain in these patients involves increases in both muscle mass and adipose tissue. Upon validation, these findings could have implications for clinical trial design and for translational research in cancer cachexia.

Phase 2 study of the efficacy and safety of ponsegromab in patients with cancer cachexia: PROACC-1 study design.

BACKGROUND: Cancer cachexia is a multifactorial metabolic wasting syndrome characterized by anorexia, unintentional loss of weight involving both skeletal muscle and adipose tissues, progressive functional impairment and reduced survival. Therapeutic strategies for this serious condition are very limited. Growth differentiation factor 15 (GDF-15) is a cytokine that is implicated in cancer cachexia and may represent both a biomarker of cancer cachexia and a potential therapeutic target. Ponsegromab is a potent and selective humanized monoclonal antibody that inhibits GDF-15-mediated signalling. Preclinical and preliminary phase 1 data suggest that ponsegromab-mediated inactivation of circulating GDF-15 may lead to improvement in key characteristics of cachexia. The primary objective of this phase 2 study is to assess the effect of ponsegromab on body weight in patients with cancer, cachexia and elevated GDF-15 concentrations. Secondary objectives include assessing physical activity, physical function, actigraphy, appetite, nausea and vomiting, fatigue and safety. Exploratory objectives include evaluating pharmacokinetics, pharmacodynamics, immunogenicity, lumbar skeletal muscle index and Response Evaluation Criteria in Solid Tumors. METHODS: Approximately 168 adults with non-small-cell lung, pancreatic or colorectal cancers who have cachexia and elevated GDF-15 concentrations will be randomized in a double-blind, placebo-controlled study (NCT05546476). Participants meeting eligibility criteria will be randomized 1:1:1:1 to one of three dose groups of ponsegromab (100, 200 or 400 mg) or matching placebo administered subcutaneously every 4 weeks for an initial 12-week treatment period. This is followed by optional open-label treatment with ponsegromab of 400 mg administered every 4 weeks for up to 1 year. The primary endpoint is mean change from baseline in body weight at Week 12. A mixed model for repeated measures followed by a Bayesian Emax model will be used for the primary analysis. Secondary endpoints include physical activity, physical function and actigraphy measured by remote digital sensors; patient-reported appetite-related symptoms assessed by Functional Assessment of Anorexia-Cachexia Therapy subscale scores; anorexia/appetite, nausea and vomiting, and fatigue evaluated according to questions from the Cancer-Related Cachexia Symptom Diary; and incidence of adverse events, safety laboratory tests, vital signs and electrocardiogram abnormalities. PERSPECTIVE: Cancer-related cachexia is an area of significant unmet medical need. This study will support the clinical development of ponsegromab as a novel inhibitor of GDF-15, which may ameliorate key pathologies of cancer cachexia to improve patient symptoms, functionality and quality of life. TRIAL REGISTRATION: ClinicalTrials.gov ID: NCT05546476.

Diet- and salinity-induced modifications of the gut microbiota are associated with differential physiological responses to ranavirus infection in Rana sylvatica.

Greater knowledge of how host-microbiome interactions vary with anthropogenic environmental change and influence pathogenic infections is needed to better understand stress-mediated disease outcomes. We investigated how increasing salinization in freshwaters (e.g. due to road de-icing salt runoff) and associated increases in growth of nutritional algae influenced gut bacterial assembly, host physiology and responses to ranavirus exposure in larval wood frogs (Rana sylvatica). Elevating salinity and supplementing a basic larval diet with algae increased larval growth and also increased ranavirus loads. However, larvae given algae did not exhibit elevated kidney corticosterone levels, accelerated development or weight loss post-infection, whereas larvae fed a basic diet did. Thus, algal supplementation reversed a potentially maladaptive stress response to infection observed in prior studies in this system. Algae supplementation also reduced gut bacterial diversity. Notably, we observed higher relative abundances of Firmicutes in treatments with algae-a pattern consistent with increased growth and fat deposition in mammals-that may contribute to the diminished stress responses to infection via regulation of host metabolism and endocrine function. Our study informs mechanistic hypotheses about the role of microbiome mediation of host responses to infection that can be tested in future experiments in this host-pathogen system. This article is part of the theme issue 'Amphibian immunity: stress, disease and ecoimmunology'.

Site-specific spatiotemporal occurrence and molecular congener distributions of naphthenic acids in Athabasca oil sands wetlands of Alberta, Canada.

The Athabasca oil sands region (AOSR) of Alberta, Canada is notable for its considerable unconventional petroleum extraction projects, where bitumen is extracted from naturally-occurring oil sands ore. The large scale of these heavy crude oil developments raises concerns because of their potential to distribute and/or otherwise influence the occurrence, behaviour, and fate of environmental contaminants. Naphthenic acids (NAs) are one such contaminant class of concern in the AOSR, so studies have examined the occurrence and molecular profiles of NAs in the region. We catalogued the spatiotemporal occurrence and characteristics of NAs in boreal wetlands in the AOSR over a 7-year period, using derivatized liquid chromatography-tandem mass spectrometry (LC-MS/MS). Comparing median concentrations of NAs across these wetlands revealed a pattern of NAs suggesting NAs in surface waters derived from oil sands deposits. Opportunistic wetlands that formed adjacent to reclaimed overburden and other reclamation activities had the highest concentrations of NAs and consistent patterns suggestive of bitumen-derived inputs. However, similar patterns in the occurrence of NAs were also observed in undeveloped natural wetlands located above the known surface-mineable oil sands deposit that underlies the region. Intra-annual sampling results along with inter-annual comparisons across wetlands demonstrated that differences in the spatial and temporal NA concentrations were dependent on local factors, particularly when naturally occurring oil sands ores were observed in the wetland or drainage catchment.

Body composition and lung cancer-associated cachexia in TRACERx.

Cancer-associated cachexia (CAC) is a major contributor to morbidity and mortality in individuals with non-small cell lung cancer. Key features of CAC include alterations in body composition and body weight. Here, we explore the association between body composition and body weight with survival and delineate potential biological processes and mediators that contribute to the development of CAC. Computed tomography-based body composition analysis of 651 individuals in the TRACERx (TRAcking non-small cell lung Cancer Evolution through therapy (Rx)) study suggested that individuals in the bottom 20th percentile of the distribution of skeletal muscle or adipose tissue area at the time of lung cancer diagnosis, had significantly shorter lung cancer-specific survival and overall survival. This finding was validated in 420 individuals in the independent Boston Lung Cancer Study. Individuals classified as having developed CAC according to one or more features at relapse encompassing loss of adipose or muscle tissue, or body mass index-adjusted weight loss were found to have distinct tumor genomic and transcriptomic profiles compared with individuals who did not develop such features. Primary non-small cell lung cancers from individuals who developed CAC were characterized by enrichment of inflammatory signaling and epithelial-mesenchymal transitional pathways, and differentially expressed genes upregulated in these tumors included cancer-testis antigen MAGEA6 and matrix metalloproteinases, such as ADAMTS3. In an exploratory proteomic analysis of circulating putative mediators of cachexia performed in a subset of 110 individuals from TRACERx, a significant association between circulating GDF15 and loss of body weight, skeletal muscle and adipose tissue was identified at relapse, supporting the potential therapeutic relevance of targeting GDF15 in the management of CAC.

Ranavirus Amplification in Low-Diversity Amphibian Communities.

In an era where emerging infectious diseases are a serious threat to biodiversity, epidemiological patterns need to be identified, particularly the complex mechanisms driving the dynamics of multi-host pathogens in natural communities. Many amphibian species have faced unprecedented population declines associated with diseases. Yet, specific processes shaping host-pathogen relationships within and among communities for amphibian pathogens such as ranaviruses (RV) remain poorly understood. To address this gap, we conducted a comprehensive study of RV in low-diversity amphibian communities in north-western Canada to assess the effects of biotic factors (species identity, species richness, abundance) and abiotic factors (conductivity, pH) on the pathogen prevalence and viral loads. Across 2 years and 18 sites, with communities of up to three hosts (wood frog, Rana sylvatica; boreal chorus frog, Pseudacris maculata; Canadian toad, Anaxyrus hemiophrys), we observed that RV prevalence nearly doubled with each additional species in a community, suggesting an amplification effect in aquatic, as well as terrestrial life-history stages. Infection intensity among infected wood frogs and boreal chorus frogs also significantly increased with an increase in species richness. Interestingly, we did not observe any effects of host abundance or abiotic factors, highlighting the importance of including host identity and species richness when investigating multi-host pathogens. Ultimately, only such a comprehensive approach can improve our understanding of complex and often highly context-dependent host-pathogen interactions.

Transformation of bitumen-derived naphthenic acid fraction compounds across surface waters of wetlands in the Athabasca Oil Sands region.

Bitumen is extracted from oil sands in the Athabasca Oil Sands region (AOSR) of Alberta, Canada. Much of the bitumen-derived toxicity in mine waste is attributable to naphthenic acid fraction compounds (NAFCs). Mines in the AOSR are required to be returned to a natural state after closure; thus, cost-effective strategies are needed to reduce toxicity from NAFCs. Previous studies have demonstrated the capability of constructed wetlands to attenuate NAFCs. However, the capacity of wetlands in the natural environment to degrade and transform NAFCs to less toxic components is poorly understood. To better understand the spatial distribution and fate of NAFCs in natural wetlands, samples were collected across the surfaces of two mature opportunistic wetlands near active oil sands mines. The first wetland has a well-defined surface flow pathway and inflows affected by overburden containing lean bitumen ore. The second wetland, in contrast, is a stagnant water body with raw bitumen visible along its edges. For the wetland with a well defined flow path, NAFCs decreased in concentration down gradient, while oxidized NAFCs constituted a greater proportion of NAFCs with increase in flow path. Likewise there was a decrease in the molecular weights of NAFCs, similar to trends observed in constructed wetland treatment systems. In comparison, NAFCs were more uniformly distributed across the relatively stagnant wetland. Overall, these data provide new evidence that mature opportunistic wetlands in the AOSR can promote the degradation and oxidation of bitumen-derived naphthenic acids into less toxic compounds.

Activation of the hypothalamic-pituitary-adrenal axis by exogenous and endogenous GDF15.

An acute increase in the circulating concentration of glucocorticoid hormones is essential for the survival of severe somatic stresses. Circulating concentrations of GDF15, a hormone that acts in the brain to reduce food intake, are frequently elevated in stressful states. We now report that GDF15 potently activates the hypothalamic-pituitary-adrenal (HPA) axis in mice and rats. A blocking antibody to the GDNF-family receptor α-like receptor completely prevented the corticosterone response to GDF15 administration. In wild-type mice exposed to a range of stressful stimuli, circulating levels of both corticosterone and GDF15 rose acutely. In the case of Escherichia coli or lipopolysaccharide injections, the vigorous proinflammatory cytokine response elicited was sufficient to produce a near-maximal HPA response, regardless of the presence or absence of GDF15. In contrast, the activation of the HPA axis seen in wild-type mice in response to the administration of genotoxic or endoplasmic reticulum toxins, which do not provoke a marked rise in cytokines, was absent in Gdf15-/- mice. In conclusion, consistent with its proposed role as a sentinel hormone, endogenous GDF15 is required for the activation of the protective HPA response to toxins that do not induce a substantial cytokine response. In the context of efforts to develop GDF15 as an antiobesity therapeutic, these findings identify a biomarker of target engagement and a previously unrecognized pharmacodynamic effect, which will require monitoring in human studies.

Growth differentiation factor 15 neutralization does not impact anorexia or survival in lipopolysaccharide-induced inflammation.

Growth differentiation factor 15 (GDF15) causes anorexia and weight loss in animal models, and higher circulating levels are associated with cachexia and reduced survival in cancer and other chronic diseases such as sepsis. To investigate the role of sepsis-induced GDF15, we examined whether GDF15 neutralization via a validated and highly potent monoclonal antibody, mAB2, modulates lipopolysaccharide (LPS)-induced anorexia, weight loss, and mortality in rodents. LPS injection transiently increased circulating GDF15 in wild-type mice, decreased food intake and body weight, and increased illness behavior and mortality at a high dose. GDF15 neutralization with mAB2 did not prevent or exacerbate any of the effects of LPS. Similarly, in GDF15 knockout mice, the LPS effect on appetite and survival was comparable with that observed in wild-type controls. Therefore, effective inhibition of circulating active GDF15 via an antibody or via gene knockout demonstrated that survival in the LPS acute inflammation model was independent of GDF15.

Characterization of naphthenic acid fraction compounds in water from Athabasca oil sands wetlands by Orbitrap high-resolution mass spectrometry.

Classical naphthenic acids (NAs) are known to be primary aquatic toxicants of concern in the Athabasca oil sands region (AOSR), and are a component of naphthenic acid fraction compounds (NAFCs). Recent studies conducted in the AOSR have examined metals and polycyclic aromatic hydrocarbons in regional wetlands. However, few studies have described NAs and/or NAFCs in AOSR wetlands. To address this gap, we examined NAFC profiles in the water of different wetlands in the AOSR, including naturalized borrow pits (i.e., abandoned pits created by excavation of road-building materials), and opportunistically-formed wetlands associated with reclamation activities. For comparison, NAFC profiles from these wetlands were compared to an opportunistic wetland formed from tailings pond dyke seepage. Samples were prepared using solid-phase extraction and analyzed using negative-ion high-resolution Orbitrap mass spectrometry. Principal component analyses (PCA) revealed patterns to the NAFC profiles in the wetlands. The first distinct grouping of wetlands included water bodies associated with reclamation activities that are located on and/or adjacent to mining overburden. One other wetland, HATS5w, separated from all other wetlands during PCA, and had a unique NAFC profile; detailed examination of NAFCs revealed HATS5w contained the heaviest (i.e., high m/z components) and most unsaturated NAFCs among study locations, demonstrating the usefulness of high-resolution mass spectrometry for characterizing individual wetlands. The NAFCs of HATS5w are also substantially different from bitumen-derived inputs in overburden-adjacent opportunistic wetlands. Collectively, the NAFC profiles presented provide new information on background levels of polar bitumen-derived organics in AOSR wetlands.

GDF-15 Neutralization Alleviates Platinum-Based Chemotherapy-Induced Emesis, Anorexia, and Weight Loss in Mice and Nonhuman Primates.

Platinum-based cancer therapy is restricted by dose-limiting side effects and is associated with elevation of growth differentiation factor 15 (GDF-15). But whether this elevation contributes to such side effects has been unclear. Here, we explored the effects of GDF-15 blockade on platinum-based chemotherapy-induced emesis, anorexia, and weight loss in mice and/or nonhuman primate models. We found that circulating GDF-15 is higher in subjects with cancer receiving platinum-based chemotherapy and is positively associated with weight loss in colorectal cancer (NCT00609622). Further, chemotherapy agents associated with high clinical emetic score induce circulating GDF-15 and weight loss in mice. Platinum-based treatment-induced anorexia and weight loss are attenuated in GDF-15 knockout mice, while GDF-15 neutralization with the monoclonal antibody mAB1 improves survival. In nonhuman primates, mAB1 treatment attenuates anorexia and emesis. These results suggest that GDF-15 neutralization is a potential therapeutic approach to alleviate chemotherapy-induced side effects and improve the quality of life.

Characterization of cachexia in the human fibrosarcoma HT-1080 mouse tumour model.

BACKGROUND: Cancer cachexia is a complex metabolic disease with unmet medical need. Although many rodent models are available, none are identical to the human disease. Therefore, the development of new preclinical models that simulate some of the physiological, biochemical, and clinical characteristics of the human disease is valuable. The HT-1080 human fibrosarcoma tumour cell line was reported to induce cachexia in mice. Therefore, the purpose of this work was to determine how well the HT-1080 tumour model could recapitulate human cachexia and to examine its technical performance. Furthermore, the efficacy of ghrelin receptor activation via anamorelin treatment was evaluated, because it is one of few clinically validated mechanisms. METHODS: Female severe combined immunodeficient mice were implanted subcutaneously or heterotopically (renal capsule) with HT-1080 tumour cells. The cachectic phenotype was evaluated during tumour development, including body weight, body composition, food intake, muscle function (force and fatigue), grip strength, and physical activity measurements. Heterotopic and subcutaneous tumour histology was also compared. Energy balance was evaluated at standard and thermoneutral housing temperatures in the subcutaneous model. The effect of anamorelin (ghrelin analogue) treatment was also examined. RESULTS: The HT-1080 tumour model had excellent technical performance and was reproducible across multiple experimental conditions. Heterotopic and subcutaneous tumour cell implantation resulted in similar cachexia phenotypes independent of housing temperature. Tumour weight and histology was comparable between both routes of administration with minimal inflammation. Subcutaneous HT-1080 tumour-bearing mice presented with weight loss (decreased fat mass and skeletal muscle mass/fibre cross-sectional area), reduced food intake, impaired muscle function (reduced force and grip strength), and decreased spontaneous activity and voluntary wheel running. Key circulating inflammatory biomarkers were produced by the tumour, including growth differentiation factor 15, Activin A, interleukin 6, and TNF alpha. Anamorelin prevented but did not reverse anorexia and weight loss in the subcutaneous model. CONCLUSIONS: The subcutaneous HT-1080 tumour model displays many of the perturbations of energy balance and physical performance described in human cachexia, consistent with the production of key inflammatory factors. Anamorelin was most effective when administered early in disease progression. The HT-1080 tumour model is valuable for studying potential therapeutic targets for the treatment of cachexia.

Resveratrol Inhibits Neointimal Growth after Arterial Injury in High-Fat-Fed Rodents: The Roles of SIRT1 and AMPK.

We have shown that both insulin and resveratrol (RSV) decrease neointimal hyperplasia in chow-fed rodents via mechanisms that are in part overlapping and involve the activation of endothelial nitric oxide synthase (eNOS). However, this vasculoprotective effect of insulin is abolished in high-fat-fed insulin-resistant rats. Since RSV, in addition to increasing insulin sensitivity, can activate eNOS via pathways that are independent of insulin signaling, such as the activation of sirtuin 1 (SIRT1) and AMP-activated kinase (AMPK), we speculated that unlike insulin, the vasculoprotective effect of RSV would be retained in high-fat-fed rats. We found that high-fat feeding decreased insulin sensitivity and increased neointimal area and that RSV improved insulin sensitivity (p < 0.05) and decreased neointimal area in high-fat-fed rats (p < 0.05). We investigated the role of SIRT1 in the effect of RSV using two genetic mouse models. We found that RSV decreased neointimal area in high-fat-fed wild-type mice (p < 0.05), an effect that was retained in mice with catalytically inactive SIRT1 (p < 0.05) and in heterozygous SIRT1-null mice. In contrast, the effect of RSV was abolished in AMKPα2-null mice. Thus, RSV decreased neointimal hyperplasia after arterial injury in both high-fat-fed rats and mice, an effect likely not mediated by SIRT1 but by AMPKα2.

Pharmacologic or genetic activation of SIRT1 attenuates the fat-induced decrease in beta-cell function in vivo.

BACKGROUND: There is evidence that sirtuin 1 (SIRT1), a key regulator of nutrient metabolism, increases ß-cell secretory function. Excess circulating fat, as seen in obesity, has been shown to decrease ß-cell function, an effect that may involve decreased SIRT1 activity. Consequently, SIRT1 activation may increase ß-cell function in conditions of elevated plasma-free fatty acid levels. Here we attempted to attenuate the lipid-induced decrease in ß-cell function in vivo using pharmacological and genetic models of SIRT1 activation. METHODS: Our pharmacologic model involved 48 h intravenous infusion of Wistar rats with either saline or oleate with or without the SIRT1 activator resveratrol. Additionally, we used ß-cell-specific SIRT1 overexpressing (BESTO) mice and wild-type littermates infused for 48 h intravenously with either saline or oleate. In both models, the infusion period was followed by assessment of ß-cell function using the hyperglycemic clamp method. RESULTS: Lipid infusion resulted in a significant decrease in ß-cell function as expected in both rats (p < 0.05) and mice (p < 0.001). Both models of SIRT1 activation, which did not alter ß-cell function in the absence of fat, resulted in partial protection from the fat-induced decrease in ß-cell function (NS vs. control). CONCLUSION: These results suggest that SIRT1 is a therapeutic target in decreased ß-cell function specifically induced by fat.

Using wood frog (Lithobates sylvaticus) tadpoles and semipermeable membrane devices to monitor polycyclic aromatic compounds in boreal wetlands in the oil sands region of northern Alberta, Canada.

Several recent studies have reported evidence that surface mining operations of bitumen in northern Alberta's oil sands (OS) region contribute significantly to the atmospheric deposition of metals and polycyclic aromatic compounds (PACs) within the vicinity of OS development. The present study examines the accumulation of PACs in boreal wetlands at varying distance from OS industrial activities with the use of semipermeable membrane devices (SPMDs) and wood frog (Lithobates sylvaticus) tadpoles. SPMDs were deployed in shallow lentic waterbodies adjacent to wood frog egg masses and were retrieved, along with tadpoles, approximately 35-45 days later. The highest concentrations of PACs were detected in SPMDs deployed within a 25 km radius of surface mining activity, consistent with snow deposition studies of PACs in the region. In wetlands located within the vicinity of surface mining activity, PAC profiles of SPMDs and wood frog tadpoles were dominated by C1-C4 alkylated PACs, including alkylated dibenzothiophenes, which are strongly indicative of petrogenic sources. Contrary to differences seen in the SPMD PAC concentrations, there were no obvious differences in the ∑PACs in wood frog tissue between wetland study sites, although alkylated fluorenes were found to be higher in tadpoles collected from a wetland located within 10 km of two bitumen upgrading facilities. The use of SPMDs in tandem with wood frog tadpoles can help assess the potential exposure of aquatic organisms to PACs in boreal wetlands.

SSB recruitment of Exonuclease I aborts template-switching in Escherichia coli.

Misalignment of a nascent strand and the use of an alternative template during DNA replication, a process termed "template-switching", can give rise to frequent mutations and genetic rearrangements. Mutational hotspots are frequently found associated with imperfect inverted repeats ("quasipalindromes" or "QPs") in many organisms, including bacteriophage, bacteria, yeast and mammals. Evidence suggests that QPs mutate by a replication template-switch whereby one copy of the inverted repeat templates synthesis of the other. To study quasipalindrome-associated mutagenesis ("QPM") more systematically, we have engineered mutational reporters in the lacZ gene of Escherichia coli, that revert to Lac+ specifically by QPM. We and others have shown that QPM is more efficient during replication of the leading strand than it is on the lagging strand. We have previously shown that QPM is elevated and that the leading-strand bias is lost in mutants lacking the major 3' ssDNA exonucleases, ExoI and ExoVII. This suggests that one or both of these exonucleases more efficiently abort template-switches on the lagging strand. Here, we show that ExoI is primarily responsible for this bias and that its ability to be recruited by single-strand DNA binding protein plays a critical role in QPM avoidance and strand bias. In addition to these stand-alone exonucleases, loss of the 3' proofreading exonuclease activity of the replicative DNA polymerase III also greatly elevates QPM. This may be because template-switching is initiated by base misincorporation, leading to polymerase dissociation and subsequent nascent strand misalignment; alternatively or additionally, the proofreading exonuclease may scavenge displaced 3' DNA that would otherwise be free to misalign.

High-dose metformin (420mg/kg daily p.o.) increases insulin sensitivity but does not affect neointimal thickness in the rat carotid balloon injury model of restenosis.

OBJECTIVE: Our laboratory has shown that insulin's effect to decrease neointimal thickness after arterial injury is greatly diminished in insulin resistant conditions. Thus, in these conditions, a better alternative to insulin could be to use an insulin sensitizing agent. Metformin, the most commonly prescribed insulin sensitizer, has a cardiovascular protective role. Therefore, the objective of this study was to investigate the potential benefit of metformin on neointimal area after arterial injury in a rat model of restenosis. METHODS: Rats fed with either normal or high fat diet and treated with or without oral metformin (420mg/kg daily) underwent carotid balloon injury. Effects of metformin on clamp-determined insulin sensitivity, vessel AMPK (AMP-activated protein kinase) phosphorylation (activation marker) and neointimal area were evaluated. RESULTS: Metformin increased insulin sensitivity, but did not affect neointimal thickness in either the normal fat or high fat diet-fed rats. Furthermore, metformin activated AMPK in uninjured but not in injured vessels. Similarly, 10mmol/L metformin inhibited proliferation and activated AMPK in smooth muscle cells of uninjured but not injured vessels, whereas 2mmol/L metformin did not have any effect. CONCLUSION: In rats, metformin does not decrease neointimal growth after arterial injury, despite increasing whole body insulin sensitivity.

Resveratrol prevents insulin resistance caused by short-term elevation of free fatty acids in vivo.

Elevated levels of plasma free fatty acids (FFA), which are commonly found in obesity, induce insulin resistance. FFA activate protein kinases including the proinflammatory IκBα kinase ß (IKKß), leading to serine phosphorylation of insulin receptor substrate 1 (IRS-1) and impaired insulin signaling. To test whether resveratrol, a polyphenol found in red wine, prevents FFA-induced insulin resistance, we used a hyperinsulinemic-euglycemic clamp with a tracer to assess hepatic and peripheral insulin sensitivity in overnight-fasted Wistar rats infused for 7 h with saline, Intralipid plus 20 U·mL(-1) heparin (IH; triglyceride emulsion that elevates FFA levels in vivo; 5.5 µL·min(-1)) with or without resveratrol (3 mg·kg(-1)·h(-1)), or resveratrol alone. Infusion of IH significantly decreased glucose infusion rate (GIR; P < 0.05) and peripheral glucose utilization (P < 0.05) and increased endogenous glucose production (EGP; P < 0.05) during the clamp compared with saline infusion. Resveratrol co-infusion, however, completely prevented the effects induced by IH infusion: it prevented the decreases in GIR (P < 0.05 vs. IH), peripheral glucose utilization (P < 0.05 vs. IH), and insulin-induced suppression of EGP (P < 0.05 vs. IH). Resveratrol alone had no effect. Furthermore, IH infusion increased serine (307) phosphorylation of IRS-1 in soleus muscle (∼30-fold, P < 0.001), decreased total IRS-1 levels, and decreased IκBα content, consistent with activation of IKKß. Importantly, all of these effects were abolished by resveratrol (P < 0.05 vs. IH). These results suggest that resveratrol prevents FFA-induced hepatic and peripheral insulin resistance and, therefore, may help mitigate the health consequences of obesity.

The effect of insulin to decrease neointimal growth after arterial injury is endothelial nitric oxide synthase-dependent.

In vitro, insulin has mitogenic effects on vascular smooth muscle cells (VSMC) but also has protective effects on endothelial cells by stimulating nitric oxide (NO) production and endothelial nitric oxide synthase (eNOS) expression. Furthermore, NOS inhibition attenuates the effect of insulin to inhibit VSMC migration in vitro. Using an in vivo model, we have previously shown that insulin decreases neointimal growth and cell migration and increases re-endothelialization after arterial injury in normal rats. Since insulin can stimulate NOS, and NO can decrease neointimal growth, we hypothesized that NOS, and more specifically eNOS was required for the effects of insulin in vivo. Rats were given subcutaneous insulin implants (3 U/day) alone or with the NOS inhibitor l-NAME (2 mg kg(-1) day(-1)) 3 days before arterial (carotid or aortic) balloon catheter injury. Insulin decreased both neointimal area (P < 0.01) and cell migration (P < 0.01), and increased re-endothelialization (P < 0.05). All of these effects were prevented by the co-administration of l-NAME. Insulin was found to decrease inducible NOS expression (P < 0.05) but increase eNOS phosphorylation (P < 0.05). These changes were also translated at the functional level where insulin improved endothelial-dependent vasorelaxation. To further study the NOS isoform involved in insulin action, s.c. insulin (0.1 U/day) was given to wild-type and eNOS knockout mice. We found that insulin was effective at decreasing neointimal formation in wild-type mice after wire injury of the femoral artery, whereas this effect of insulin was absent in eNOS knockout mice. These results show that the vasculoprotective effect of insulin after arterial injury is mediated by an eNOS-dependent mechanism.

Latest approaches for the treatment of obesity.

INTRODUCTION: Obesity is a body weight disorder characterized by excess adiposity that increases the risk for developing co-morbidities such as type 2 diabetes. A large medical need exists for new anti-obesity treatments capable of promoting 10% or greater weight loss, with minimal side effects. AREAS COVERED: The authors describe the application of monogenic forms of rare obesity and genome-wide association studies in selecting critical pathways for drug discovery. Furthermore, they review in detail several pathways and pharmacological targets in the central nervous system (e.g., the leptin-melanocortin axis, the opioid system, GLP-1/GLP-1 system, and FGF21/FGFR1c/ß-Klotho axis) that play an important role in the regulation of feeding behavior and energy homeostasis. Special focus is given to new strategies that engage well-known targets via novel mechanisms in order to circumvent issues seen with previous drug candidates that failed in the clinic. Finally, the authors discuss the recent developments around fixed-dose combinations, targeted polypharmacology, and non-traditional combinations of drugs and devices. EXPERT OPINION: The future for new weight-loss approaches to treat obesity looks promising. Current therapies have shown modest effects on weight loss in the general obese population but will have greater impact in smaller homogeneous sub-populations of obese subjects using personalized medicine. Drug combinations that target multiple, complementary pathways have the potential to promote double-digit weight loss in a broader, heterogeneous patient population. Furthermore, the development of advanced subcutaneous delivery technologies has opened up opportunities to develop breakthrough peptide and biologic agents for the treatment of obesity.