216 research outputs found

    Uncovering the Structural Diversity of Y(III) Naphthalene-2,6-Dicarboxylate MOFs Through Coordination Modulation

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    Metal-organic frameworks (MOFs)—network structures built from metal ions or clusters and connecting organic ligands—are typically synthesized by solvothermal self-assembly. For transition metal based MOFs, structural predictability is facilitated by control over coordination geometries and linker connectivity under the principles of isoreticular synthesis. For rare earth (RE) MOFs, coordination behavior is dominated by steric and electronic factors, leading to unpredictable structures, and poor control over self-assembly. Herein we show that coordination modulation—the addition of competing ligands into MOF syntheses—offers programmable access to six different Y(III) MOFs all connected by the same naphthalene-2,6-dicarboxylate ligand, despite controlled synthesis of multiple phases from the same metal-ligand combination often being challenging for rare earth MOFs. Four of the materials are isolable in bulk phase purity, three are amenable to rapid microwave synthesis, and the fluorescence sensing ability of one example toward metal cations is reported. The results show that a huge variety of structurally versatile MOFs can potentially be prepared from simple systems, and that coordination modulation is a powerful tool for systematic control of phase behavior in rare earth MOFs

    An integrated functional genomic study of acute phenobarbital exposure in the rat.

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    BACKGROUND: Non-genotoxic carcinogens are notoriously difficult to identify as they do not damage DNA directly and have diverse modes of action, necessitating long term in vivo studies. The early effects of the classic rodent non-genotoxic hepatocarcinogen phenobarbital have been investigated in the Fisher rat using a combination of metabolomics and transcriptomics, to investige early stage mechanistic changes that are predictive of longer term pathology. RESULTS: Liver and blood plasma were profiled across 14 days, and multivariate statistics used to identify perturbed pathways. Both metabolomics and transcriptomics detected changes in the liver which were dose dependent, even after one day of exposure. Integration of the two datasets associated perturbations with specific pathways. Hepatic glycogen was decreased due to a decrease in synthesis, and plasma triglycerides were decreased due to an increase in fatty acid uptake by the liver. Hepatic succinate was increased and this was associated with increased heme biosynthesis. Glutathione synthesis was also increased, presumably in response to oxidative stress. Liquid Chromatography Mass Spectrometry demonstrated a remodeling of lipid species, possibly resulting from proliferation of the smooth endoplasmic reticulum. CONCLUSIONS: The data fusion of metabolomic and transcriptomic changes proved to be a highly sensitive approach for monitoring early stage changes in altered hepatic metabolism, oxidative stress and cytochrome P450 induction simultaneously. This approach is particularly useful in interpreting changes in metabolites such as succinate which are hubs of metabolism.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

    "Post-GDM support would be really good for mothers": A qualitative interview study exploring how to support a healthy diet and physical activity after gestational diabetes.

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    BACKGROUND: Women with a history of gestational diabetes mellitus (GDM) are at high risk of developing type 2 diabetes mellitus (T2DM). They are therefore recommended to follow a healthy diet and be physically active in order to reduce that risk. However, achieving and maintaining these behaviours in the postpartum period is challenging. This study sought to explore women's views on suggested practical approaches to achieve and maintain a healthy diet and physical activity to reduce T2DM risk. METHODS: Semi-structured interviews with 20 participants in Cambridgeshire, UK were conducted at three to 48 months after GDM. The participants' current diet and physical activity, intentions for any changes, and views on potential interventions to help manage T2DM risk through these behaviours were discussed. Framework analysis was used to analyse the transcripts. The interview schedule, suggested interventions, and thematic framework were based on a recent systematic review. RESULTS: Most of the participants wanted to eat more healthily and be more active. A third of the participants considered that postpartum support for these behaviours would be transformative, a third thought it would be beneficial, and a third did not want additional support. The majority agreed that more information about the impact of diet and physical activity on diabetes risk, support to exercise with others, and advice about eating healthily, exercising with a busy schedule, monitoring progress and sustaining changes would facilitate a healthy diet and physical activity. Four other suggested interventions received mixed responses. It would be acceptable for this support to be delivered throughout pregnancy and postpartum through a range of formats. Clinicians were seen to have important roles in giving or signposting to support. CONCLUSIONS: Many women would appreciate more support to reduce their T2DM risk after GDM and believe that a variety of interventions to integrate changes into their daily lives would help them to sustain healthier lifestyles.RAD was funded by a PhD studentship from the National Institute for Health Research (NIHR) School for Primary Care Research (SPCR; SPCR-S-S102). This paper presents independent research funded by the NIHR SPCR. The views expressed are those of the author(s) and not necessarily those of the NIHR, the NHS or the Department of Health. JAUS was funded by a Cancer Research UK Cancer Prevention Fellowship (C55650/A21464). SJG is supported by the Medical Research Council (MC_UU_12015/4). The University of Cambridge has received salary support in respect of SJG from the NHS in the East of England through the Clinical Academic Reserve. CEA is supported by an Action Medical Research Grant (GN2778) and a Medical Research Council New Investigator Research Grant (MR/T016701/1). CLM is supported by the Diabetes UK Harry Keen Intermediate Clinical Fellowship (DUK-HKF 17/0005712) and the European Foundation for the Study of Diabetes – Novo Nordisk Foundation Future Leaders’ Award (NNF19SA058974). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

    Combination Lopinavir and Ritonavir Alter Exogenous and Endogenous Bile Acid Disposition in Sandwich-Cultured Rat Hepatocytes

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    Inhibition of the bile salt export pump (BSEP) can cause intracellular accumulation of bile acids and is a risk factor for drug-induced liver injury in humans. Antiretroviral protease inhibitors lopinavir (LPV) and ritonavir (RTV) are reported BSEP inhibitors. However, the consequences of LPV and RTV, alone and combined (LPV/r), on hepatocyte viability, bile acid transport, and endogenous bile acid disposition in rat hepatocytes have not been examined. The effect of LPV, RTV, and LPV/r on cellular viability and the disposition of [3H]taurocholic acid (TCA) and [14C]chenodeoxycholic acid (CDCA) was determined in sandwich-cultured rat hepatocytes (SCRH) and suspended rat hepatocytes. Lactate dehydrogenase and ATP assays revealed a concentration-dependent effect of LPV and RTV on cellular viability. LPV (5 µM), alone and combined with 5 µM RTV, significantly decreased [3H]TCA accumulation in cells + bile of SCRHs compared with control. LPV/r significantly increased [3H]TCA cellular accumulation (7.7 ± 0.1 pmol/mg of protein) compared with vehicle and 5 µM LPV alone (5.1 ± 0.7 and 5.0 ± 0.5 pmol/mg of protein). The [3H]TCA biliary clearance was reduced significantly by LPV and RTV and further reduced by LPV/r. LPV and RTV did not affect the initial uptake rates of [3H]TCA or [14C]CDCA in suspended rat hepatocytes. LPV (50 µM), RTV (5 µM), and LPV/r (5 and 50 µM/5 µM) significantly decreased the accumulation of total measured endogenous bile acids (TCA, glycocholic acid, taurochenodeoxycholic acid, glycochenodeoxycholic acid, and α/β-tauromuricholic acid) in SCRH. Quantification of endogenous bile acids in SCRH may reveal important adaptive responses associated with exposure to known BSEP inhibitors

    Elevated circulating amyloid concentrations in obesity and diabetes promote vascular dysfunction

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    Diabetes, obesity and Alzheimer’s disease (AD) are associated with vascular complications and impaired nitric oxide (NO) production. Furthermore, increased β-site amyloid precursor protein (APP)-cleaving enzyme 1 (BACE1), APP and β-amyloid (Aβ) are linked with vascular disease development and raised BACE1 and Aβ accompany hyperglycemia and hyperlipidemia. However, the causal relationship between obesity and diabetes, raised Aβ and vascular dysfunction is unclear. We report that diet-induced obesity (DIO) in mice raised plasma and vascular Aβ42 that correlated with decreased NO bioavailability, endothelial dysfunction and raised blood pressure. Genetic or pharmacological reduction of BACE1 activity and Aβ42 prevented and reversed, respectively, these outcomes. In contrast, expression of human mutant APP in mice or Aβ42 infusion into control diet-fed mice to mimic obese levels impaired NO production, vascular relaxation and raised blood pressure. In humans, raised plasma Aβ42 correlated with diabetes and endothelial dysfunction. Mechanistically, higher Aβ42 reduced endothelial NO synthase (eNOS), cyclic GMP and protein kinase G (PKG) activity independently of diet whereas endothelin-1 was increased by diet and Aβ42. Lowering Aβ42 reversed the DIO deficit in the eNOS-cGMP-PKG pathway and decreased endothelin-1. Our findings suggest that BACE1 inhibitors may have therapeutic value in the treatment of vascular disease associated with diabetes

    The genomic architecture of novel Simulium damnosum Wolbachia prophage sequence elements and implications for onchocerciasis epidemiology

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    Research interest in Wolbachia is growing as new discoveries and technical advancements reveal the public health importance of both naturally occurring and artificial infections. Improved understanding of the Wolbachia bacteriophages (WOs) WOcauB2 and WOcauB3 [belonging to a sub-group of four WOs encoding serine recombinases group 1 (sr1WOs)], has enhanced the prospect of novel tools for the genetic manipulation of Wolbachia. The basic biology of sr1WOs, including host range and mode of genomic integration is, however, still poorly understood. Very few sr1WOs have been described, with two such elements putatively resulting from integrations at the same Wolbachia genome loci, about 2 kb downstream from the FtsZ cell-division gene. Here, we characterize the DNA sequence flanking the FtsZ gene of wDam, a genetically distinct line of Wolbachia isolated from the West African onchocerciasis vector Simulium squamosum E. Using Roche 454 shot-gun and Sanger sequencing, we have resolved >32 kb of WO prophage sequence into three contigs representing three distinct prophage elements. Spanning ≥36 distinct WO open reading frame gene sequences, these prophage elements correspond roughly to three different WO modules: a serine recombinase and replication module (sr1RRM), a head and base-plate module and a tail module. The sr1RRM module contains replication genes and a Holliday junction recombinase and is unique to the sr1 group WOs. In the extreme terminal of the tail module there is a SpvB protein homolog—believed to have insecticidal properties and proposed to have a role in how Wolbachia parasitize their insect hosts. We propose that these wDam prophage modules all derive from a single WO genome, which we have named here sr1WOdamA1. The best-match database sequence for all of our sr1WOdamA1-predicted gene sequences was annotated as of Wolbachia or Wolbachia phage sourced from an arthropod. Clear evidence of exchange between sr1WOdamA1 and other Wolbachia WO phage sequences was also detected. These findings provide insights into how Wolbachia could affect a medically important vector of onchocerciasis, with potential implications for future control methods, as well as supporting the hypothesis that Wolbachia phages do not follow the standard model of phage evolution

    Mechanistic insights revealed by lipid profiling in monogenic insulin resistance syndromes.

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    BACKGROUND: Evidence from several recent metabolomic studies suggests that increased concentrations of triacylglycerols with shorter (14-16 carbon atoms), saturated fatty acids are associated with insulin resistance and the risk of type 2 diabetes. Although causality cannot be inferred from association studies, patients in whom the primary cause of insulin resistance can be genetically defined offer unique opportunities to address this challenge. METHODS: We compared metabolite profiles in patients with congenital lipodystrophy or loss-of-function insulin resistance (INSR gene) mutations with healthy controls. RESULTS: The absence of significant differences in triacylglycerol species in the INSR group suggest that changes previously observed in epidemiological studies are not purely a consequence of insulin resistance. The presence of triacylglycerols with lower carbon numbers and high saturation in patients with lipodystrophy suggests that these metabolite changes may be associated with primary adipose tissue dysfunction. The observed pattern of triacylglycerol species is indicative of increased de novo lipogenesis in the liver. To test this we investigated the distribution of these triacylglycerols in lipoprotein fractions using size exclusion chromatography prior to mass spectrometry. This associated these triacylglycerols with very low-density lipoprotein particles, and hence release of triacylglycerols into the blood from the liver. To test further the hepatic origin of these triacylglycerols we induced de novo lipogenesis in the mouse, comparing ob/ob and wild-type mice on a chow or high fat diet, confirming that de novo lipogenesis induced an increase in relatively shorter, more saturated fatty acids. CONCLUSIONS: Overall, these studies highlight hepatic de novo lipogenesis in the pathogenesis of metabolic dyslipidaemia in states where energy intake exceeds the capacity of adipose tissue

    Uncertainty, evidence and irrecoverable costs: informing approval, pricing and research decisions for health technologies

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    The general issue of balancing the value of evidence about the performance of a technology and the value of access to a technology can be seen as central to a number of policy questions. Establishing the key principles of what assessments are needed, as well as how they should be made, will enable them to be addressed in an explicit and transparent manner. This report presents the key finding from MRC and NHIR funded research which aimed to: i) Establish the key principles of what assessments are needed to inform an only in research (OIR) or Approval with Research (AWR) recommendation. ii) Evaluate previous NICE guidance where OIR or AWR recommendations were made or considered. iii) Evaluate a range of alternative options to establish the criteria, additional information and/or analysis which could be made available to help the assessment needed to inform an OIR or AWR recommendation. iv) Provide a series of final recommendations, with the involvement of key stakeholders, establishing both the key principles and associated criteria that might guide OIR and AWR recommendations, identifying what, if any, additional information or analysis might be included in the Technology Appraisal process and how such recommendations might be more likely to be implemented through publicly funded and sponsored research. The key principles and the assessments and judgments required are discussed in Section 2. The sequence of assessment and judgment is represented as an algorithm, which can also be summarised as a simple set of explicit criteria or a seven point checklist of assessments. The application of the check list of assessment to a series of four case studies in Section 3 can inform considerations of whether such assessments can be made based on existing information and analysis in current NICE appraisal and in what circumstances could additional information and/or analysis be useful. In Section 4, some of the implications that this more explicit assessment of OIR and AWR might have for policy (e.g., NICE guidance and drug pricing), the process of appraisal (e.g., greater involvement of research commissioners) and methods of appraisal (e.g., should additional information, evidence and analysis be required) are drawn together

    Decreased Fatty Acid Transporter FABP1 and Increased Isoprostanes and Neuroprostanes in the Human Term Placenta: Implications for Inflammation and Birth Weight in Maternal Pre-Gestational Obesity.

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    The rise in prevalence of obesity in women of reproductive age in developed and developing countries might propagate intergenerational cycles of detrimental effects on metabolic health. Placental lipid metabolism is disrupted by maternal obesity, which possibly affects the life-long health of the offspring. Here, we investigated placental lipid metabolism in women with pre-gestational obesity as a sole pregnancy complication and compared it to placental responses of lean women. Open profile and targeted lipidomics were used to assess placental lipids and oxidised products of docosahexaenoic (DHA) and arachidonic acid (AA), respectively, neuroprostanes and isoprostanes. Despite no overall signs of lipid accumulation, DHA and AA levels in placentas from obese women were, respectively, 2.2 and 2.5 times higher than those from lean women. Additionally, a 2-fold increase in DHA-derived neuroprostanes and a 1.7-fold increase in AA-derived isoprostanes were seen in the obese group. These changes correlated with a 70% decrease in placental FABP1 protein. Multivariate analyses suggested that neuroprostanes and isoprostanes are associated with maternal and placental inflammation and with birth weight. These results might shed light on the molecular mechanisms associated with altered placental fatty acid metabolism in maternal pre-gestational obesity, placing these oxidised fatty acids as novel mediators of placental function
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