Showing papers by "Mark E. Cooper published in 2014"
TL;DR: This article identified 697 variants at genome-wide significance that together explained one-fifth of the heritability for adult height, and all common variants together captured 60% of heritability.
Abstract: Using genome-wide data from 253,288 individuals, we identified 697 variants at genome-wide significance that together explained one-fifth of the heritability for adult height. By testing different numbers of variants in independent studies, we show that the most strongly associated ∼2,000, ∼3,700 and ∼9,500 SNPs explained ∼21%, ∼24% and ∼29% of phenotypic variance. Furthermore, all common variants together captured 60% of heritability. The 697 variants clustered in 423 loci were enriched for genes, pathways and tissue types known to be involved in growth and together implicated genes and pathways not highlighted in earlier efforts, such as signaling by fibroblast growth factors, WNT/β-catenin and chondroitin sulfate-related genes. We identified several genes and pathways not previously connected with human skeletal growth, including mTOR, osteoglycin and binding of hyaluronic acid. Our results indicate a genetic architecture for human height that is characterized by a very large but finite number (thousands) of causal variants.
1,872 citations
TL;DR: More effective therapies to slow progressive loss of β-cell function are needed and additional long-term studies of drugs and bariatric surgery are needed to identify new ways to prevent and treat type 2 diabetes and thereby reduce the harmful effects of this disease.
1,219 citations
The George Institute for Global Health1, University of Sydney2, Baker IDI Heart and Diabetes Institute3, Bond University4, Utrecht University5, Université de Montréal6, University of Melbourne7, University of Sheffield8, University of Milan9, University of Paris10, University of Oxford11, Aarhus University12, University College London13, Johns Hopkins University14
TL;DR: There was no evidence that intensive glucose control during the ADVANCE factorial trial led to long-term benefits with respect to mortality or macrovascular events.
Abstract: Background In the Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE) factorial trial, the combination of perindopril and indapamide reduced mortality among patients with type 2 diabetes, but intensive glucose control, targeting a glycated hemoglobin level of less than 6.5%, did not. We now report results of the 6-year post-trial follow-up. Methods We invited surviving participants, who had previously been assigned to perindopril–indapamide or placebo and to intensive or standard glucose control (with the glucose-control comparison extending for an additional 6 months), to participate in a post-trial follow-up evaluation. The primary end points were death from any cause and major macrovascular events. Results The baseline characteristics were similar among the 11,140 patients who originally underwent randomization and the 8494 patients who participated in the post-trial follow-up for a median of 5.9 years (blood-pressure–lowering comparison) or ...
492 citations
TL;DR: The next few years will be critical for NP-driven lead discovery, and a concerted effort is required to identify new biologically active pharmacophores and to progress these and existing compounds through pre-clinical drug development into clinical trials.
456 citations
TL;DR: In patients with type 2 diabetes, age or age at diagnosis and diabetes duration are independent associated with macrovascular events and death whereas only diabetes duration is independently associated with microv vascular events and this effect is greater in the youngest patients.
Abstract: Data are inconsistent regarding the associations between age, age at diagnosis of diabetes, diabetes duration and subsequent vascular complications. The associations between age (or age at diagnosis), diabetes duration and major macrovascular events, all-cause death and major microvascular events were examined in 11,140 patients with type 2 diabetes randomly allocated to intensive or standard glucose control in the Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE) trial. Rates were calculated by 5 year baseline age (or age at diagnosis) and diabetes duration strata. Risks were estimated using Cox models adjusted for treatment assignment and HbA1c. The mean age (±SD) was 65.8 ± 6.4 years, age at diagnosis was 57.8 ± 8.7 years and diabetes duration was 7.9 ± 6.4 years. Diabetes duration was associated with the risk of macrovascular events (HR 1.13 [95% CI 1.08, 1.17]), microvascular events (1.28 [1.23, 1.33]) and death (1.15 [1.10, 1.20]) whereas age (or age at diagnosis) was only associated with the risk of macrovascular events (1.33 [1.27, 1.39]) and death (1.56 [1.48, 1.64]). No interaction was observed between diabetes duration, age and the risk of macrovascular events or death (both p > 0.4). However, an interaction was observed between diabetes duration, age and the risk of microvascular events (p = 0.002), such that the effects of increasing diabetes duration were greatest at younger rather than older age. In patients with type 2 diabetes, age or age at diagnosis and diabetes duration are independently associated with macrovascular events and death whereas only diabetes duration is independently associated with microvascular events and this effect is greater in the youngest patients.
324 citations
TL;DR: Advances in crop growth modelling methodology are being used to evaluate the integrated effects of multiple traits for their combined effects and evaluate drought hybrid product concepts and guide their development and evaluation.
Abstract: Germplasm, genetics, phenotyping, and selection, combined with a clear definition of product targets, are the foundation of successful hybrid maize breeding. Breeding maize hybrids with superior yield for the drought-prone regions of the US corn-belt involves integration of multiple drought-specific technologies together with all of the other technology components that comprise a successful maize hybrid breeding programme. Managed-environment technologies are used to enable scaling of precision phenotyping in appropriate drought environmental conditions to breeding programme level. Genomics and other molecular technologies are used to study trait genetic architecture. Genetic prediction methodology was used to breed for improved yield performance for drought-prone environments. This was enabled by combining precision phenotyping for drought performance with genetic understanding of the traits contributing to successful hybrids in the target drought-prone environments and the availability of molecular markers distributed across the maize genome. Advances in crop growth modelling methodology are being used to evaluate the integrated effects of multiple traits for their combined effects and evaluate drought hybrid product concepts and guide their development and evaluation. Results to date, lessons learned, and future opportunities for further improving the drought tolerance of maize for the US corn-belt are discussed.
309 citations
TL;DR: In human podocytes, silencing of the Nox4 gene resulted in reduced production of ROS and downregulation of proinflammatory and profibrotic markers that are implicated in diabetic nephropathy, and provide proof of principle for an innovative small molecule approach to treat and/or prevent chronic kidney failure.
Abstract: Diabetic nephropathy may occur, in part, as a result of intrarenal oxidative stress. NADPH oxidases comprise the only known dedicated reactive oxygen species (ROS)–forming enzyme family. In the rodent kidney, three isoforms of the catalytic subunit of NADPH oxidase are expressed (Nox1, Nox2, and Nox4). Here we show that Nox4 is the main source of renal ROS in a mouse model of diabetic nephropathy induced by streptozotocin administration in ApoE−/− mice. Deletion of Nox4, but not of Nox1, resulted in renal protection from glomerular injury as evidenced by attenuated albuminuria, preserved structure, reduced glomerular accumulation of extracellular matrix proteins, attenuated glomerular macrophage infiltration, and reduced renal expression of monocyte chemoattractant protein-1 and NF-κB in streptozotocin-induced diabetic ApoE−/− mice. Importantly, administration of the most specific Nox1/4 inhibitor, GKT137831, replicated these renoprotective effects of Nox4 deletion. In human podocytes, silencing of the Nox4 gene resulted in reduced production of ROS and downregulation of proinflammatory and profibrotic markers that are implicated in diabetic nephropathy. Collectively, these results identify Nox4 as a key source of ROS responsible for kidney injury in diabetes and provide proof of principle for an innovative small molecule approach to treat and/or prevent chronic kidney failure.
304 citations
TL;DR: In this review, examples will be drawn primarily from the experience gained through commercial maize breeding, and implications for other crops, in both the private and public sectors, will be discussed.
Abstract: For the foreseeable future, plant breeding methodology will continue to unfold as a practical application of the scaling of quantitative biology. These efforts to increase the effective scale of breeding programs will focus on the immediate and long-term needs of society. The foundations of the quantitative dimension will be integration of quantitative genetics, statistics, gene-to-phenotype knowledge of traits embedded within crop growth and development models. The integration will be enabled by advances in quantitative genetics methodology and computer simulation. The foundations of the biology dimension will be integrated experimental and functional gene-to-phenotype modelling approaches that advance our understanding of functional germplasm diversity, and gene-to-phenotype trait relationships for the native and transgenic variation utilised in agricultural crops. The trait genetic knowledge created will span scales of biology, extending from molecular genetics to multi-trait phenotypes embedded within evolving genotype–environment systems. The outcomes sought and successes achieved by plant breeding will be measured in terms of sustainable improvements in agricultural production of food, feed, fibre, biofuels and other desirable plant products that meet the needs of society. In this review, examples will be drawn primarily from our experience gained through commercial maize breeding. Implications for other crops, in both the private and public sectors, will be discussed.
275 citations
TL;DR: Consistency of glycemic control is important to reduce the risks of vascular events and death in type 2 diabetes.
Abstract: OBJECTIVE There is no consensus on the importance of visit-to-visit glycemic variability in diabetes. Therefore, we assessed the effects of visit-to-visit variability (VVV) in HbA 1c and fasting glucose on major outcomes in the ADVANCE (Action in Diabetes and Vascular Disease: Preterax and Diamicron MR Controlled Evaluation) trial. RESEARCH DESIGN AND METHODS ADVANCE was a factorial randomized controlled trial of intensive glucose control and blood pressure lowering in patients with type 2 diabetes. VVV in the intensive glucose treatment group was defined using the SD of five measurements of HbA 1c and glucose taken 3–24 months after randomization. Outcomes were combined macro- and microvascular events and all-cause mortality occurring post 24 months. Sensitivity analyses were performed using other indices of variability and in the standard glucose treatment group. RESULTS Among 4,399 patients in the intensive group, an increase in VVV of HbA 1c was associated with an increased risk of vascular events ( P = 0.01) and with mortality ( P P 1c variability was positively associated with the risk of macrovascular events ( P = 0.02 for trend), whereas glucose variability was associated with both macro- and microvascular events ( P = 0.005 and P CONCLUSIONS Consistency of glycemic control is important to reduce the risks of vascular events and death in type 2 diabetes.
271 citations
TL;DR: In this review, the discovery, development and associated resistance of vancomycin and teicoplanin, and semi-synthetic glycopeptides, telavancin (3), dalbavancein (4) and oritavancIn (5), are detailed and the clinical implications of glycopePTide resistance, as well as the future prospects for current glycopesptide drugs and the development of new glycopeptic drugs are discussed.
Abstract: Glycopeptide antibiotics have been a key weapon in the fight against bacterial infections for over half a century, with the progenitors, vancomycin (1) and teicoplanin (2), still used extensively. The increased occurrence of resistance and the effectiveness of these ‘last resort’ treatments for Gram-positive infections has led to the discovery and clinical development of second generation, semisynthetic lipoglycopeptide derivatives such as telavancin (3), dalbavancin (4) and oritavancin (5), which all possess broader spectra of activity and improved pharmacokinetic properties. Two of these new antibiotics, telavancin (3) and dalbavancin (4), were approved in the past 5 years and the third, oritavancin (5), is awaiting regulatory approval. In this review, the discovery, development and associated resistance of vancomycin (1) and teicoplanin (2), and semi-synthetic glycopeptides, telavancin (3), dalbavancin (4) and oritavancin (5), are detailed. The clinical implications of glycopeptide resistance, especially vancomycin (1), as well as the future prospects for current glycopeptide drugs and the development of new glycopeptides are discussed.
199 citations
TL;DR: Let-7b microRNA represents a potential new target for the treatment of renal fibrosis in diabetic and non-diabetic nephropathy with the upregulation of TGFBR1.
TL;DR: It is shown that the inability of open-state PsaA to satisfy the preferred coordination chemistry of manganese enables the protein to undergo the conformational changes required for cargo release to the Psa permease, whereas zinc ions remain bound to PSAA.
Abstract: The PsaA binding protein delivers Mn2+ to the human pathogen Streptococcus pneumoniae. Structural and biochemical studies now explain its metal specificity, showing that metal binding induces a closed complex that is reversible for the desired substrate but irreversible for the inhibitor Zn2+.
TL;DR: Overall, blood plasma was found to be highly regulated, with few elements exhibiting strong, if any, correlation with ambient concentrations, and seasonal changes in physiology governed intra-annual variations in blood chemistry and, by implication, also regulate ion availability to the otolith.
Abstract: Most studies that infer geographic distributions of fish using otolith microchemistry assume that environmental factors (e.g. temperature, salinity) outweigh intrinsic effects (e.g. size, condition); however, this assumption has not been rigorously tested, particularly in marine fish. Here, we report the results of a long-term experimental study of European plaice Pleuronectes platessa L. and explore relationships between blood plasma and ambient water chemistry over a 12 mo reproductive cycle. Overall, blood plasma was found to be highly regulated, with few elements exhibiting strong, if any, correlation with ambient concentrations. This sets a first order limit on the sensitivity of otolith chemistry to fluctuations in ambient seawater chemistry. The observed temporal, ontogenetic and sex-specific variations in blood plasma elemental concentrations indicated significant physiological influences on elemental uptake and processing mechanisms. Physiological variables exerted relatively strong influences on the uptake and regulation of the softer, more thiophilic elements (Mn, Cu, Zn, Se and Pb), as well as Sr and Ca. By contrast, seasonal and sex-related variations were relatively minor among the hard acid metal ions (Li+, Mg2+, K+, Rb+, Ba2+). Overall, plasma elemental concentrations covaried most strongly and consistently with plasma protein concentrations. For this exclusively marine species, seasonal changes in physiology governed intra-annual variations in blood chemistry and, by implication, also regulate ion availability to the otolith. Based on these observations, we recommend that sex and age should be controlled for in future experimental designs using otolith microchemistry to infer stock structure or migration patterns.
TL;DR: It is shown that renal Nox5 is upregulated in human diabetic nephropathy and may alter filtration barrier function and systolic BP through the production of reactive oxygen species.
Abstract: NADPH oxidase (Nox) enzymes are a significant source of reactive oxygen species, which contribute to glomerular podocyte dysfunction. Although studies have implicated Nox1, -2, and -4 in several glomerulopathies, including diabetic nephropathy, little is known regarding the role of Nox5 in this context. We examined Nox5 expression and regulation in kidney biopsies from diabetic patients, cultured human podocytes, and a novel mouse model. Nox5 expression increased in human diabetic glomeruli compared with nondiabetic glomeruli. Stimulation with angiotensin II upregulated Nox5 expression in human podocyte cultures and increased reactive oxygen species generation. siRNA-mediated Nox5 knockdown inhibited angiotensin II-stimulated production of reactive oxygen species and altered podocyte cytoskeletal dynamics, resulting in an Rac-mediated motile phenotype. Because the Nox5 gene is absent in rodents, we generated transgenic mice expressing human Nox5 in a podocyte-specific manner (Nox5(pod+)). Nox5(pod+) mice exhibited early onset albuminuria, podocyte foot process effacement, and elevated systolic BP. Subjecting Nox5(pod+) mice to streptozotocin-induced diabetes further exacerbated these changes. Our data show that renal Nox5 is upregulated in human diabetic nephropathy and may alter filtration barrier function and systolic BP through the production of reactive oxygen species. These findings provide the first evidence that podocyte Nox5 has an important role in impaired renal function and hypertension.
TL;DR: These studies are the first to identify the NOX1 isoform as having an important role in the pathogenesis of retinopathy of prematurity and suggest that strategies targeting Nox1 have the potential to be effective treatments for a range of ischemic retinopathies.
Abstract: Aims: Ischemic retinal diseases such as retinopathy of prematurity are major causes of blindness due to damage to the retinal microvasculature. Despite this clinical situation, retinopathy of prematurity is mechanistically poorly understood. Therefore, effective preventative therapies are not available. However, hypoxic-induced increases in reactive oxygen species (ROS) have been suggested to be involved with NADPH oxidases (NOX), the only known dedicated enzymatic source of ROS. Our major aim was to determine the contribution of NOX isoforms (1, 2, and 4) to a rodent model of retinopathy of prematurity. Results: Using a genetic approach, we determined that only mice with a deletion of NOX1, but not NOX2 or NOX4, were protected from retinal neovascularization and vaso-obliteration, adhesion of leukocytes, microglial accumulation, and the increased generation of proangiogenic and proinflammatory factors and ROS. We complemented these studies by showing that the specific NOX inhibitor, GKT137831, reduced vasculopathy and ROS levels in retina. The source of NOX isoforms was evaluated in retinal vascular cells and neuro-glial elements. Microglia, the immune cells of the retina, expressed NOX1, 2, and 4 and responded to hypoxia with increased ROS formation, which was reduced by GKT137831. Innovation: Our studies are the first to identify the NOX1 isoform as having an important role in the pathogenesis of retinopathy of prematurity. Conclusions: Our findings suggest that strategies targeting NOX1 have the potential to be effective treatments for a range of ischemic retinopathies. Antioxid. Redox Signal. 20, 2726–2740.
TL;DR: A single transgene ARGOS1 positively impacts yield of field-grown hybrid maize, consistent with a single-locus heterotic effect of elite hybrid breeding germplasm.
Abstract: Crop improvement for yield and drought tolerance is challenging due to the complex genetic nature of these traits and environmental dependencies. This study reports that transgenic over-expression of Zea mays AR GOS1 (ZAR1) enhanced maize organ growth, grain yield, and drought-stress tolerance. The ZAR1 transgene exhibited environmental interactions, with yield increase under Temperate Dry and yield reduction under Temperate Humid or High Latitude environments. Native ZAR1 allele variation associated with drought-stress tolerance. Two founder alleles identified in the mid-maturity germplasm of North America now predominate in Pioneer's modern breeding programme, and have distinct proteins, promoters and expression patterns. These two major alleles show heterotic group partitioning, with one predominant in Pioneer's female and the other in the male heterotic groups, respectively. These two alleles also associate with favourable crop performance when heterozygous. Allele-specific transgene testing showed that, of the two alleles discussed here, each allele differed in their impact on yield and environmental interactions. Moreover, when transgenically stacked together the allelic pair showed yield and environmental performance advantages over either single allele, resembling heterosis effects. This work demonstrates differences in transgenic efficacy of native alleles and the differences reflect their association with hybrid breeding performance.
04 Dec 2014
TL;DR: The results indicate a genetic architecture for human height that is characterized by a very large but finite number of causal variants, including mTOR, osteoglycin and binding of hyaluronic acid.
Abstract: Using genome-wide data from 253,288 individuals, we identified 697 variants at genome-wide significance that together explained one-fifth of the heritability for adult height. By testing different numbers of variants in independent studies, we show that the most strongly associated ∼2,000, ∼3,700 and ∼9,500 SNPs explained ∼21%, ∼24% and ∼29% of phenotypic variance. Furthermore, all common variants together captured 60% of heritability. The 697 variants clustered in 423 loci were enriched for genes, pathways and tissue types known to be involved in growth and together implicated genes and pathways not highlighted in earlier efforts, such as signaling by fibroblast growth factors, WNT/β-catenin and chondroitin sulfate–related genes. We identified several genes and pathways not previously connected with human skeletal growth, including mTOR, osteoglycin and binding of hyaluronic acid. Our results indicate a genetic architecture for human height that is characterized by a very large but finite number (thousands) of causal variants.
TL;DR: It is shown that dh404, at lower but not higher doses, significantly lessens diabetes-associated atherosclerosis with reductions in oxidative stress and proinflammatory mediators tumor necrosis factor-α, intracellular adhesion molecule-1, vascular cell adhesion molecules- 1, and monocyte chemotactic protein-1 (MCP-1).
Abstract: Oxidative stress and inflammation are inextricably linked and play essential roles in the initiation and progression of diabetes complications such as diabetes-associated atherosclerosis and nephropathy. Bolstering antioxidant defenses is an important mechanism to lessen oxidative stress and inflammation. In this study, we have used a novel analog of the NFE2-related factor 2 (Nrf2) agonist bardoxolone methyl, dh404, to investigate its effects on diabetic macrovascular and renal injury in streptozotocin-induced diabetic apolipoprotein E(-/-) mice. We show that dh404, at lower but not higher doses, significantly lessens diabetes-associated atherosclerosis with reductions in oxidative stress (in plasma, urine, and vascular tissue) and proinflammatory mediators tumor necrosis factor-α, intracellular adhesion molecule-1, vascular cell adhesion molecule-1, and monocyte chemotactic protein-1 (MCP-1). We demonstrate that dh404 attenuates functional (urinary albumin-to-creatinine ratio) and structural (mesangial expansion) glomerular injury and improves renal tubular injury. Liver functional and structural studies showed that dh404 is well tolerated. Complementary in vitro studies in normal rat kidney cells showed that dh404 significantly upregulates Nrf2-responsive genes, heme oxygenase-1, NAD(P)H quinone oxidoreductase 1, and glutathione-S transferase, with inhibition of transforming growth factor-β-mediated profibrotic fibronectin, collagen I, and proinflammatory interleukin-6. Higher doses of dh404 were associated with increased expression of proinflammatory mediators MCP-1 and nuclear factor-κB. These findings suggest that this class of compound is worthy of further study to lessen diabetes complications but that dosage needs consideration.
TL;DR: Examination of the effects of global deletion of a NADPH‐oxidase isoform, Nox4, was examined in mice with streptozotocin‐induced diabetes to suggest that deletion of Nx4 may alleviate renal injury via PKC‐dependent mechanisms, further strengthening the view that Nox 4 is a suitable target for renoprotection in diabetes.
Abstract: Current treatments for diabetic nephropathy (DN) only result in slowing its progression, thus highlighting a need to identify novel targets. Increased production of reactive oxygen species (ROS) is considered a key downstream pathway of end-organ injury with increasing data implicating both mitochondrial and cytosolic sources of ROS. The enzyme, NADPH oxidase, generates ROS in the kidney and has been implicated in the activation of protein kinase C (PKC), in the pathogenesis of DN, but the link between PKC and Nox-derived ROS has not been evaluated in detail in vivo. In this study, global deletion of a NADPH-oxidase isoform, Nox4, was examined in mice with streptozotocin-induced diabetes (C57Bl6/J) in order to evaluate the effects of Nox4 deletion, not only on renal structure and function but also on the PKC pathway and downstream events. Nox4 deletion attenuated diabetes-associated increases in albuminuria, glomerulosclerosis, and extracellular matrix accumulation. Lack of Nox4 resulted in a decrease in diabetes-induced renal cortical ROS derived from the mitochondria and the cytosol, urinary isoprostanes, and PKC activity. Immunostaining of renal cortex revealed that major isoforms of PKC, PKC-α and PKC-β1, were increased with diabetes and normalized by Nox4 deletion. Downregulation of the PKC pathway was observed in tandem with reduced expression of vascular endothelial growth factor (VEGF), transforming growth factor (TGF)-β1 and restoration of the podocyte slit pore protein nephrin. This study suggests that deletion of Nox4 may alleviate renal injury via PKC-dependent mechanisms, further strengthening the view that Nox4 is a suitable target for renoprotection in diabetes.
TL;DR: These data provide a link between IL-10, synovial regulation of the NLRP3 inflammasome and the degree of bone erosions observed in inflammatory arthritis.
Abstract: Activation of the inflammasome has been implicated in the pathology of various autoinflammatory and autoimmune diseases. While the NLRP3 inflammasome has been linked to arthritis progression, little is known about its synovial regulation or contribution to joint histopathology. Regulators of inflammation activation, such as interleukin (IL)-10, may have the potential to limit the inflammasome-driven arthritic disease course and associated structural damage. Hence, we used IL-10-deficient (IL-10KO) mice to assess NLRP3 inflammasome-driven arthritic pathology. Antigen-induced arthritis (AIA) was established in IL-10KO mice and wild-type controls. Using histological and radiographic approaches together with quantitative real-time PCR of synovial mRNA studies, we explored the regulation of inflammasome components. These were combined with selective blocking agents and ex vivo investigative studies in osteoclast differentiation assays. In AIA, IL-10KO mice display severe disease with increased histological and radiographic joint scores. Here, focal bone erosions were associated with increased tartrate-resistant acid phosphatase (TRAP)-positive cells and a localized expression of IL-1β. When compared to controls, IL-10KO synovium showed increased expression of Il1b, Il33 and NLRP3 inflammasome components. Synovial Nlrp3 and Casp1 expression further correlated with Acp5 (encoding TRAP), while neutralization of IL-10 receptor signaling in control mice caused increased expression of Nlrp3 and Casp1. In ex vivo osteoclast differentiation assays, addition of exogenous IL-10 or selective blockade of the NLRP3 inflammasome inhibited osteoclastogenesis. These data provide a link between IL-10, synovial regulation of the NLRP3 inflammasome and the degree of bone erosions observed in inflammatory arthritis.
TL;DR: It is demonstrated that increasing plasma MG to levels observed in diabetic mice either using an exogenous source or generated following inhibition, its primary clearance enzyme, glyoxalase-1, was able to increase vascular adhesion and augment atherogenesis in euglycemic apolipoprotein E knockout mice to a similar magnitude as that observed in hyperglycemic mice with diabetes.
Abstract: The deleterious effects of high glucose levels and enhanced metabolic flux on the vasculature are thought to be mediated by the generation of toxic metabolites, including reactive dicarbonyls like methylglyoxal (MG). In this article, we demonstrate that increasing plasma MG to levels observed in diabetic mice either using an exogenous source (1% in drinking water) or generated following inhibition, its primary clearance enzyme, glyoxalase-1 (with 50 mg/kg IP bromobenzyl-glutathione cyclopentyl diester every second day), was able to increase vascular adhesion and augment atherogenesis in euglycemic apolipoprotein E knockout mice to a similar magnitude as that observed in hyperglycemic mice with diabetes. The effects of MG appear partly mediated by activation of the receptor for advanced glycation end products (RAGE), as deletion of RAGE was able to reduce inflammation and atherogenesis associated with MG exposure. However, RAGE deletion did not completely prevent inflammation or vascular damage, possibly because the induction of mitochondrial oxidative stress by dicarbonyls also contributes to inflammation and atherogenesis. Such data would suggest that a synergistic combination of RAGE antagonism and antioxidants may offer the greatest utility for the prevention and management of diabetic vascular complications.
TL;DR: The work reveals variations among strong and weak competing ligands, such as proteins in human serum, that determine dosages in drug therapies and will help develop better treatments, including choice of drugs as well as dosages, against pathogens.
Abstract: A nanomechanical sensor can quantify the concentration of active free drugs in human serum.
TL;DR: An improved understanding of C5a2 modulation of signaling in acute inflammation could be of benefit in the development of ligands for conditions such as sepsis.
Abstract: The complement system is a major component of our innate immune system, in which the complement proteins C5a and C5a-des Arg bind to two G-protein-coupled receptors: namely, the C5a receptor (C5a1) and C5a receptor like-2 receptor (C5a2, formerly called C5L2). Recently, it has been demonstrated that C5a, but not C5a-des Arg, upregulates heteromer formation between C5a1 and C5a2, leading to an increase in IL-10 release from human monocyte-derived macrophages (HMDMs). A bioluminescence resonance energy transfer (BRET) assay was used to assess the recruitment of β-arrestins by C5a and C5a-des Arg at the C5a1 and C5a2 receptors. C5a demonstrated elevated β-arrestin 2 recruitment levels in comparison with C5a-des Arg, whereas no significant difference was observed at C5a2. A constitutive complex that formed between β-arrestin 2 and C5a2 accounted for half of the BRET signal observed. Interestingly, both C5a and C5a-des Arg exhibited higher potency for β-arrestin 2 recruitment via C5a2, indicating preference for C5a2 over C5a1. When C5a was tested in a functional ERK1/2 assay in HMDMs, inhibition of ERK1/2 was observed only at concentrations at or above the EC50 for heteromer formation. This suggested that increased recruitment of the β-arrestin-C5a2 complex at these C5a concentrations might have an inhibitory role on C5a1 signaling through ERK1/2. An improved understanding of C5a2 modulation of signaling in acute inflammation could be of benefit in the development of ligands for conditions such as sepsis.
TL;DR: A post hoc analysis in the Reduction of Endpoints in NIDDM with the Angiotensin II Antagonist Losartan (RENAAL) trial and the Irbesartan Diabetic Nephropathy Trial (IDNT) indicates an independent inverse association of bilirubin with progression of nephropathy in RENAAL and IDNT.
Abstract: Bilirubin, a potent endogenous antioxidant, was found to protect against the development of diabetic nephropathy (DN) in rodents. In humans, cross-sectional studies found an inverse relation between bilirubin and DN. We prospectively investigated whether bilirubin is associated with progression of DN toward end-stage renal disease (ESRD). To this end, we performed a post hoc analysis in the Reduction of Endpoints in NIDDM with the Angiotensin II Antagonist Losartan (RENAAL) trial with independent replication in the Irbesartan Diabetic Nephropathy Trial (IDNT). Subjects with type 2 diabetes and nephropathy with alanine aminotransferase, aspartate aminotransferase (AST), and bilirubin levels <1.5 times the upper limit of normal were included. The renal end point was defined as the composite of confirmed doubling of serum creatinine or ESRD. Bilirubin was inversely associated with the renal end point in RENAAL independent of age, sex, race, BMI, smoking, total cholesterol, diastolic blood pressure, HbA1c, treatment, estimated glomerular filtration rate, albumin-to-creatinine ratio, and AST. These results were confirmed in IDNT. This study indicates an independent inverse association of bilirubin with progression of nephropathy in RENAAL and IDNT. These data suggest a protective effect of bilirubin against progression of nephropathy in type 2 diabetes. The well-established role of bilirubin as an antioxidant is a potential explanation for the findings.
TL;DR: Clues to understanding how to block PAR2 signalling associated with disease without inhibiting PAR2 activation in normal physiology could be provided by studies of biased signalling.
Abstract: andincreased ERK1/2 phosphorylation. In human kidney tubule cells, GB88 inhibited cytokine secretion (IL6, IL8, GM-CSF, TNF-α)mediated by PAR2. A rat paw oedema induced by PAR2 agonists was also inhibited by orally administered GB88 andcompared with effects of locally administered inhibitors of G-protein coupled pathways.
TL;DR: The findings suggest that the resistant derivative of K. pneumoniae can block the electrostatically driven first stage of polymyxin action, which thereby renders the hydrophobically driven second tier of poly myxinaction on the outer membrane inconsequential.
Abstract: This study examines the interaction of polymyxin B and colistin with the surface and outer membrane components of a susceptible and resistant strain of Klebsiella pneumoniae. The interaction between polymyxins and bacterial membrane and isolated LPS from paired wild type and polymyxin-resistant strains of K. pneumoniae were examined with N-phenyl-1-naphthylamine (NPN) uptake, fluorometric binding and thermal shift assays, lysozyme and deoxycholate sensitivity assays, and by 1H NMR. LPS from the polymyxin-resistant strain displayed a reduced binding affinity for polymyxins B and colistin in comparison with the wild type LPS. The outer membrane NPN permeability of the resistant strain was greater compared with the susceptible strain. Polymyxin exposure enhanced the permeability of the outer membrane of the wild type strain to lysozyme and deoxycholate, whereas polymyxin concentrations up to 32 mg/ml failed to permeabilize the outer membrane of the resistant strain. Zeta potential measurements revealed that mid-logarithmic phase wild type cells exhibited a greater negative charge than the mid-logarithmic phase-resistant cells. Taken together, our findings suggest that the resistant derivative of K. pneumoniae can block the electrostatically driven first stage of polymyxin action, which thereby renders the hydrophobically driven second tier of polymyxin action on the outer membrane inconsequential.
TL;DR: Blockade of NOX-derived ROS using the NOX inhibitor GKT137831 is associated with attenuation of these changes in the immune response and reduces the diabetes-accelerated development of atherosclerotic plaques in Apoe−/− mice.
Abstract: Aims/hypothesis
Enhanced vascular inflammation, immune cell infiltration and elevated production of reactive oxygen species (ROS) contribute significantly to pro-atherogenic responses in diabetes We assessed the immunomodulatory role of NADPH oxidase (NOX)-derived ROS in diabetes-accelerated atherosclerosis
TL;DR: In this paper, the authors show that (inter)glacial cycles in sediment color and %CaCO3 pre-date major northern hemisphere glaciation and are unambiguously and consistently correlated to benthic oxygen isotopes back to 3.3 million years ago (Ma) and intermittently so probably back to the Miocene/Pliocene boundary.
TL;DR: The correlation observed between membrane depolarization and bacterial cell viability suggests that this mechanism may contribute to the bactericidal activity of ramoplanin.
Abstract: Ramoplanin is an actinomycetes-derived antibiotic with broad-spectrum activity against Gram-positive bacteria that has been evaluated in clinical trials for the treatment of gastrointestinal vancomycin-resistant enterococci (VRE) and Clostridium difficile infections. Recent studies have proposed that ramoplanin binds to bacterial membranes as a C2 symmetrical dimer that can sequester Lipid II, which causes inhibition of cell wall peptidoglycan biosynthesis and cell death. In this study, ramoplanin was shown to bind to anionic and zwitterionic membrane mimetics with a higher affinity for anionic membranes and to induce membrane depolarization of methicillin-susceptible Staphylococcus aureus (MSSA) ATCC 25923 at concentrations at or above the minimal bactericidal concentration (MBC). The ultrastructural effects of ramoplanin on S. aureus were also examined by transmission electron microscopy (TEM), and this showed dramatic changes to bacterial cell morphology. The correlation observed between membrane depolarization and bacterial cell viability suggests that this mechanism may contribute to the bactericidal activity of ramoplanin.
TL;DR: This review discusses traditional and emerging kidney injury biomarkers that are used for the determination of nephrotoxicity and for evaluation and diagnosis of other kidney diseases and the potential for in vivo biomarkers to predict renal toxicity in high-throughput in vitro screening assays is discussed.
Abstract: Introduction: Drug-induced nephrotoxicity contributes to the failure rate of investigational drugs during clinical trials. We are still not able to accurately predict drug-induced nephrotoxicity during early drug discovery and development. There is an urgent need for a robust screening system that can identify nephrotoxic compounds before they reach the clinic.Areas covered: This review discusses traditional and emerging kidney injury biomarkers that are used for the determination of nephrotoxicity and for evaluation and diagnosis of other kidney diseases. The potential for in vivo biomarkers to predict renal toxicity in high-throughput in vitro screening assays is discussed. We also compare cell types and highlight novel three-dimensional (3D) culture technologies with potential for in vitro prediction of nephrotoxicity.Expert opinion: Traditional cell culture methods and cytotoxicity assays are well established as in vitro tests for nephrotoxicity but the correlation with in vivo results is extremely po...