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3,209 result(s) for "Breen, David S."
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Inhibition of hepatic lipogenesis enhances liver tumorigenesis by increasing antioxidant defence and promoting cell survival
The metabolic pathway of de novo lipogenesis is frequently upregulated in human liver tumours, and its upregulation is associated with poor prognosis. Blocking lipogenesis in cultured liver cancer cells is sufficient to decrease cell viability; however, it is not known whether blocking lipogenesis in vivo can prevent liver tumorigenesis. Herein, we inhibit hepatic lipogenesis in mice by liver-specific knockout of acetyl-CoA carboxylase (ACC) genes and treat the mice with the hepatocellular carcinogen diethylnitrosamine (DEN). Unexpectedly, mice lacking hepatic lipogenesis have a twofold increase in tumour incidence and multiplicity compared to controls. Metabolomics analysis of ACC-deficient liver identifies a marked increase in antioxidants including NADPH and reduced glutathione. Importantly, supplementing primary wild-type hepatocytes with glutathione precursors improves cell survival following DEN treatment to a level indistinguishable from ACC-deficient primary hepatocytes. This study shows that lipogenesis is dispensable for liver tumorigenesis in mice treated with DEN, and identifies an important role for ACC enzymes in redox regulation and cell survival. The lipogenic pathway is often upregulated in liver tumours and regarded as a therapeutic target. Here, the authors show instead that blocking lipogenesis via knockout of acetyl-CoA carboxylase genes results in increased susceptibility to liver tumorigenesis associated with an increased antioxidant defence.
Dietary sugar intake increases liver tumor incidence in female mice
Overnutrition can promote liver cancer in mice and humans that have liver damage caused by alcohol, viruses, or carcinogens. However, the mechanism linking diet to increased liver tumorigenesis remains unclear in the context of whether tumorigenesis is secondary to obesity, or whether nutrients like sugar or fat drive tumorigenesis independent of obesity. In male mice, liver tumor burden was recently found to correlate with sugar intake, independent of dietary fat intake and obesity. However, females are less susceptible to developing liver cancer than males and it remains unclear how nutrition affects tumorigenesis in females. Herein, female mice were exposed to the liver carcinogen diethylnitrosamine (DEN) and fed diets with well-defined sugar and fat content. Mice fed diets with high sugar content had the greatest liver tumor incidence while dietary fat intake was not associated with tumorigenesis. Diet-induced postprandial hyperglycemia and fasting hyperinsulinemia significantly correlated with tumor incidence, while tumor incidence was not associated with obesity and obesity-related disorders including liver steatosis, glucose intolerance, or elevated serum levels of estrogen, ALT and lipids. These results simplify the pathophysiology of diet-induced liver tumorigenesis by focusing attention on the role of sugar metabolism and reducing emphasis on the complex milieu associated with obesity.
A major role for common genetic variation in anxiety disorders
Anxiety disorders are common, complex psychiatric disorders with twin heritabilities of 30–60%. We conducted a genome-wide association study of Lifetime Anxiety Disorder (ncase = 25 453, ncontrol = 58 113) and an additional analysis of Current Anxiety Symptoms (ncase = 19 012, ncontrol = 58 113). The liability scale common variant heritability estimate for Lifetime Anxiety Disorder was 26%, and for Current Anxiety Symptoms was 31%. Five novel genome-wide significant loci were identified including an intergenic region on chromosome 9 that has previously been associated with neuroticism, and a locus overlapping the BDNF receptor gene, NTRK2. Anxiety showed significant positive genetic correlations with depression and insomnia as well as coronary artery disease, mirroring findings from epidemiological studies. We conclude that common genetic variation accounts for a substantive proportion of the genetic architecture underlying anxiety.
An integrated genetic-epigenetic analysis of schizophrenia: evidence for co-localization of genetic associations and differential DNA methylation
Background Schizophrenia is a highly heritable, neuropsychiatric disorder characterized by episodic psychosis and altered cognitive function. Despite success in identifying genetic variants associated with schizophrenia, there remains uncertainty about the causal genes involved in disease pathogenesis and how their function is regulated. Results We performed a multi-stage epigenome-wide association study, quantifying genome-wide patterns of DNA methylation in a total of 1714 individuals from three independent sample cohorts. We have identified multiple differentially methylated positions and regions consistently associated with schizophrenia across the three cohorts; these effects are independent of important confounders such as smoking. We also show that epigenetic variation at multiple loci across the genome contributes to the polygenic nature of schizophrenia. Finally, we show how DNA methylation quantitative trait loci in combination with Bayesian co-localization analyses can be used to annotate extended genomic regions nominated by studies of schizophrenia, and to identify potential regulatory variation causally involved in disease. Conclusions This study represents the first systematic integrated analysis of genetic and epigenetic variation in schizophrenia, introducing a methodological approach that can be used to inform epigenome-wide association study analyses of other complex traits and diseases. We demonstrate the utility of using a polygenic risk score to identify molecular variation associated with etiological variation, and of using DNA methylation quantitative trait loci to refine the functional and regulatory variation associated with schizophrenia risk variants. Finally, we present strong evidence for the co-localization of genetic associations for schizophrenia and differential DNA methylation.
Image-guided ablation of primary liver and renal tumours
Key Points Hepatocellular carcinoma (HCC) is increasingly detected at an early, asymptomatic stage owing to surveillance programmes in at-risk patient populations Patients with early stage HCC (single tumour <5 cm or up to three nodules <3 cm) should be considered for any available curative treatments, including liver transplantation, hepatic resection, and image-guided ablation (IGA) IGA is currently recommended as the standard of care for patients with early stage HCC when surgical options are precluded, and has potential as a first-line treatment for very early stage tumours smaller than 2 cm Small (<5 cm) renal tumours, often incidentally detected at imaging for alternative symptomatology, are an increasingly problematic clinical management issue in an ageing population Active surveillance or partial nephrectomy is usually invoked after detection of small renal tumours, but both of these approaches can be onerous for patients who often have an indolent malignancy Diligent image-guided ablation, increasingly by cryoablation, represents a useful, minimally invasive treatment option with reduced costs and morbidity The use of image-guided ablation techniques—including radiofrequency and microwave ablation, cryoablation, and irreversible electroporation—is increasing, predominantly in the treatment of small hepatic and renal tumours (<5 cm). This Review describes the technical considerations for the various ablation modalities. In addition, the authors review the evidence that supports the clinical application of these minimally invasive techniques for the treatment of liver and kidney cancers, and discuss their potential as the standard-of-care first-line treatment, particularly for small, early stage tumours. Image-guided ablation (IGA) techniques have evolved considerably over the past 20 years and are increasingly used to definitively treat small primary cancers of the liver and kidney. IGA is recommended by most guidelines as the best therapeutic choice for patients with early stage hepatocellular carcinoma (HCC)—defined as either a single tumour smaller than 5 cm or up to three nodules smaller than 3 cm—when surgical options are precluded, and has potential as first-line therapy, in lieu of surgery, for patients with very early stage tumours smaller than 2 cm. With regard to renal cell carcinoma, despite the absence of any randomized trial comparing the outcomes of IGA with those of standard partial nephrectomy, a growing amount of data demonstrate robust oncological outcomes for this minimally invasive approach and testify to its potential as a standard-of-care treatment. Herein, we review the various ablation techniques, the supporting evidence, and clinical application of IGA in the treatment of primary liver and kidney cancers.
Identifying Parkinson's disease and parkinsonism cases using routinely collected healthcare data: A systematic review
Population-based, prospective studies can provide important insights into Parkinson's disease (PD) and other parkinsonian disorders. Participant follow-up in such studies is often achieved through linkage to routinely collected healthcare datasets. We systematically reviewed the published literature on the accuracy of these datasets for this purpose. We searched four electronic databases for published studies that compared PD and parkinsonism cases identified using routinely collected data to a reference standard. We extracted study characteristics and two accuracy measures: positive predictive value (PPV) and/or sensitivity. We identified 18 articles, resulting in 27 measures of PPV and 14 of sensitivity. For PD, PPV ranged from 56-90% in hospital datasets, 53-87% in prescription datasets, 81-90% in primary care datasets and was 67% in mortality datasets. Combining diagnostic and medication codes increased PPV. For parkinsonism, PPV ranged from 36-88% in hospital datasets, 40-74% in prescription datasets, and was 94% in mortality datasets. Sensitivity ranged from 15-73% in single datasets for PD and 43-63% in single datasets for parkinsonism. In many settings, routinely collected datasets generate good PPVs and reasonable sensitivities for identifying PD and parkinsonism cases. However, given the wide range of identified accuracy estimates, we recommend cohorts conduct their own context-specific validation studies if existing evidence is lacking. Further research is warranted to investigate primary care and medication datasets, and to develop algorithms that balance a high PPV with acceptable sensitivity.
Thermal ablation of colorectal liver metastases: a position paper by an international panel of ablation experts, the interventional oncology sans frontières meeting 2013
Objectives Previous attempts at meta-analysis and systematic review have not provided clear recommendations for the clinical application of thermal ablation in metastatic colorectal cancer. Many authors believe that the probability of gathering randomised controlled trial (RCT) data is low. Our aim is to provide a consensus document making recommendations on the appropriate application of thermal ablation in patients with colorectal liver metastases. Methods This consensus paper was discussed by an expert panel at The Interventional Oncology Sans Frontières 2013. A literature review was presented. Tumour characteristics, ablation technique and different clinical applications were considered and the level of consensus was documented. Results Specific recommendations are made with regard to metastasis size, number, and location and ablation technique. Mean 31 % 5-year survival post-ablation in selected patients has resulted in acceptance of this therapy for those with technically inoperable but limited liver disease and those with limited liver reserve or co-morbidities that render them inoperable. Conclusions In the absence of RCT data, it is our aim that this consensus document will facilitate judicious selection of the patients most likely to benefit from thermal ablation and provide a unified interventional oncological perspective for the use of this technology. Key Points • Best results require due consideration of tumour size, number, volume and location. • Ablation technology, imaging guidance and intra-procedural imaging assessment must be optimised. • Accepted applications include inoperable disease due to tumour distribution or inadequate liver reserve. • Other current indications include concurrent co-morbidity, patient choice and the test-of-time approach. • Future applications may include resectable disease, e.g. for small solitary tumours.
New awakenings: current understanding of sleep dysfunction and its treatment in Parkinson’s disease
The non-motor features of Parkinson’s disease (PD) are increasingly being recognised. This review deals with the spectrum of sleep disorders associated with PD, which have a multifactorial aetiology and can significantly have an impact on the quality of life of patients and their carers. Some sleep disorders represent a prodromal phase of PD, with REM sleep behaviour disorder (RBD) being of particular interest in this regard, whereas others become more common as the disease advances. Understanding the pathophysiology of these sleep disturbances will hopefully lead to new treatment opportunities in the future. The recent discovery of the glymphatic system for removal of waste products from the brain has also raised the possibility that sleep disruption may cause or accelerate the underlying disease process.
A genomics approach to understanding the role of auxin in apple (Malus x domestica)fruit size control
Background Auxin is an important phytohormone for fleshy fruit development, having been shown to be involved in the initial signal for fertilisation, fruit size through the control of cell division and cell expansion, and ripening related events. There is considerable knowledge of auxin-related genes, mostly from work in model species. With the apple genome now available, it is possible to carry out genomics studies on auxin-related genes to identify genes that may play roles in specific stages of apple fruit development. Results High amounts of auxin in the seed compared with the fruit cortex were observed in 'Royal Gala' apples, with amounts increasing through fruit development. Injection of exogenous auxin into developing apples at the start of cell expansion caused an increase in cell size. An expression analysis screen of auxin-related genes involved in auxin reception, homeostasis, and transcriptional regulation showed complex patterns of expression in each class of gene. Two mapping populations were phenotyped for fruit size over multiple seasons, and multiple quantitative trait loci (QTLs) were observed. One QTL mapped to a region containing an Auxin Response Factor ( ARF106 ). This gene is expressed during cell division and cell expansion stages, consistent with a potential role in the control of fruit size. Conclusions The application of exogenous auxin to apples increased cell expansion, suggesting that endogenous auxin concentrations are at least one of the limiting factors controlling fruit size. The expression analysis of ARF106 linked to a strong QTL for fruit weight suggests that the auxin signal regulating fruit size could partially be modulated through the function of this gene. One class of gene ( GH3 ) removes free auxin by conjugation to amino acids. The lower expression of these GH3 genes during rapid fruit expansion is consistent with the apple maximising auxin concentrations at this point.