210 research outputs found
Neutrino Signatures From Young Neutron Stars
After a successful core collapse supernova (CCSN) explosion, a hot dense proto-neutron star (PNS) is left as a remnant. Over a time of 20 or so seconds, this PNS emits the majority of the neutrinos that come from the CCSN, contracts, and loses most of its lepton number. This is the process by which all neutron stars in our galaxy are likely born. The emitted neutrinos were detected from supernova (SN) 1987A, and they will be detected in much greater numbers from any future galactic CCSN. These detections can provide a direct window into the properties of the dense matter encountered inside neutron stars, and they can affect nucleosynthesis in the material ejected during the CCSN. In this chapter, we review the basic physics of PNS cooling, including the basic equations of PNS structure and neutrino diffusion in dense matter. We then discuss how the nuclear equation of state, neutrino opacities in dense matter, and convection can shape the temporal behavior of the neutrino signal. We also discuss what was learned from the late-time SN 1987A neutrinos, the prospects for detection of these neutrinos from future galactic CCSNe, and the effects these neutrinos can have on nucleosynthesis
肥満によって遊離する脂肪細胞由来のDNA断片が脂肪組織の炎症とインスリン抵抗性を引き起こす
Obesity stimulates chronic inflammation in adipose tissue, which is associated with insulin resistance, although the underlying mechanism remains largely unknown. Here we showed that obesity-related adipocyte degeneration causes release of cell-free DNA (cfDNA), which promotes macrophage accumulation in adipose tissue via Toll-like receptor 9 (TLR9), originally known as a sensor of exogenous DNA fragments. Fat-fed obese wild-type mice showed increased release of cfDNA, as determined by the concentrations of single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) in plasma. cfDNA released from degenerated adipocytes promoted monocyte chemoattractant protein-1 (MCP-1) expression in wild-type macrophages, but not in TLR9-deficient (Tlr9−/−) macrophages. Fat-fed Tlr9−/− mice demonstrated reduced macrophage accumulation and inflammation in adipose tissue and better insulin sensitivity compared with wild-type mice, whereas bone marrow reconstitution with wild-type bone marrow restored the attenuation of insulin resistance observed in fat-fed Tlr9−/− mice. Administration of a TLR9 inhibitory oligonucleotide to fat-fed wild-type mice reduced the accumulation of macrophages in adipose tissue and improved insulin resistance. Furthermore, in humans, plasma ssDNA level was significantly higher in patients with computed tomography–determined visceral obesity and was associated with homeostasis model assessment of insulin resistance (HOMA-IR), which is the index of insulin resistance. Our study may provide a novel mechanism for the development of sterile inflammation in adipose tissue and a potential therapeutic target for insulin resistance
Role of Toll-Like Receptor 9 in Atherogenesis
Background
Toll-like receptor (TLR) 9 recognizes bacterial DNA, activating innate immunity, whereas it also provokes inflammation in response to fragmented DNA released from mammalian cells. We investigated whether TLR9 contributes to the development of vascular inflammation and atherogenesis using apolipoprotein E–deficient (Apoe-/-) mice.
Methods and Results
Tlr9-deficient Apoe-/- (Tlr9-/-Apoe-/-) mice and Apoe-/- mice on a Western-type diet received subcutaneous angiotensin II infusion (1000 ng/kg per minute) for 28 days. Angiotensin II increased the plasma level of double-stranded DNA, an endogenous ligand of TLR9, in these mice. Genetic deletion or pharmacologic blockade of TLR9 in angiotensin II–infused Apoe-/- mice attenuated atherogenesis in the aortic arch (P<0.05), reduced the accumulation of lipid and macrophages in atherosclerotic plaques, and decreased RNA expression of inflammatory molecules in the aorta with no alteration of metabolic parameters. On the other hand, restoration of TLR9 in bone marrow in Tlr9-/-Apoe-/- mice promoted atherogenesis in the aortic arch (P<0.05). A TLR9 agonist markedly promoted proinflammatory activation of Apoe-/- macrophages, partially through p38 mitogen-activated protein kinase signaling. In addition, genomic DNA extracted from macrophages promoted inflammatory molecule expression more effectively in Apoe-/- macrophages than in Tlr9-/-Apoe-/- macrophages. Furthermore, in humans, circulating double-stranded DNA in the coronary artery positively correlated with inflammatory features of coronary plaques determined by optical coherence tomography in patients with acute myocardial infarction (P<0.05).
Conclusions
TLR9 plays a pivotal role in the development of vascular inflammation and atherogenesis through proinflammatory activation of macrophages. TLR9 may serve as a potential therapeutic target for atherosclerosis
Altered Development of NKT Cells, γδ T Cells, CD8 T Cells and NK Cells in a PLZF Deficient Patient
In mice, the transcription factor, PLZF, controls the development of effector functions in invariant NKT cells and a subset of NKT cell-like, γδ T cells. Here, we show that in human lymphocytes, in addition to invariant NKT cells, PLZF was also expressed in a large percentage of CD8+ and CD4+ T cells. Furthermore, PLZF was also found to be expressed in all γδ T cells and in all NK cells. Importantly, we show that in a donor lacking functional PLZF, all of these various lymphocyte populations were altered. Therefore, in contrast to mice, PLZF appears to control the development and/or function of a wide variety of human lymphocytes that represent more than 10% of the total PBMCs. Interestingly, the PLZF-expressing CD8+ T cell population was found to be expanded in the peripheral blood of patients with metastatic melanoma but was greatly diminished in patients with autoimmune disease
Correlations among Brain Gray Matter Volumes, Age, Gender, and Hemisphere in Healthy Individuals
To determine the relationship between age and gray matter structure and how interactions between gender and hemisphere impact this relationship, we examined correlations between global or regional gray matter volume and age, including interactions of gender and hemisphere, using a general linear model with voxel-based and region-of-interest analyses. Brain magnetic resonance images were collected from 1460 healthy individuals aged 20–69 years; the images were linearly normalized and segmented and restored to native space for analysis of global gray matter volume. Linearly normalized images were then non-linearly normalized and smoothed for analysis of regional gray matter volume. Analysis of global gray matter volume revealed a significant negative correlation between gray matter ratio (gray matter volume divided by intracranial volume) and age in both genders, and a significant interaction effect of age × gender on the gray matter ratio. In analyzing regional gray matter volume, the gray matter volume of all regions showed significant main effects of age, and most regions, with the exception of several including the inferior parietal lobule, showed a significant age × gender interaction. Additionally, the inferior temporal gyrus showed a significant age × gender × hemisphere interaction. No regional volumes showed significant age × hemisphere interactions. Our study may contribute to clarifying the mechanism(s) of normal brain aging in each brain region
Distinct functions of HTLV-1 Tax1 from HTLV-2 Tax2 contribute key roles to viral pathogenesis
While the human T-cell leukemia virus type 1 (HTLV-1) is the etiologic agent of adult T-cell leukemia/lymphoma (ATL), to date, its close relative HTLV-2 is not associated with ATL or other types of malignancies. Accumulating evidence shows that HTLV-1 Tax1 and HTLV-2 Tax2 have many shared activities, but the two proteins have a limited number of significantly distinct activities, and these distinctions appear to play key roles in HTLV-1 specific pathogenesis. In this review, we summarize the functions of Tax1 associated with cell survival, cell proliferation, persistent infection as well as pathogenesis. We emphasize special attention to distinctions between Tax1 and Tax2
Gut microbiota and diabetes: from pathogenesis to therapeutic perspective
More than several hundreds of millions of people will be diabetic and obese over the next decades in front of which the actual therapeutic approaches aim at treating the consequences rather than causes of the impaired metabolism. This strategy is not efficient and new paradigms should be found. The wide analysis of the genome cannot predict or explain more than 10–20% of the disease, whereas changes in feeding and social behavior have certainly a major impact. However, the molecular mechanisms linking environmental factors and genetic susceptibility were so far not envisioned until the recent discovery of a hidden source of genomic diversity, i.e., the metagenome. More than 3 million genes from several hundreds of species constitute our intestinal microbiome. First key experiments have demonstrated that this biome can by itself transfer metabolic disease. The mechanisms are unknown but could be involved in the modulation of energy harvesting capacity by the host as well as the low-grade inflammation and the corresponding immune response on adipose tissue plasticity, hepatic steatosis, insulin resistance and even the secondary cardiovascular events. Secreted bacterial factors reach the circulating blood, and even full bacteria from intestinal microbiota can reach tissues where inflammation is triggered. The last 5 years have demonstrated that intestinal microbiota, at its molecular level, is a causal factor early in the development of the diseases. Nonetheless, much more need to be uncovered in order to identify first, new predictive biomarkers so that preventive strategies based on pre- and probiotics, and second, new therapeutic strategies against the cause rather than the consequence of hyperglycemia and body weight gain
Phase II trial of erlotinib in patients with advanced non-small-cell lung cancer harboring epidermal growth factor receptor mutations: additive analysis of pharmacokinetics
Background: We conducted a phase II trial of erlotinib in patients with advanced non-small-cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) mutations and evaluated the relationship between plasma concentration and efficacy of erlotinib. Methods: Patients who were previously treated but naive to epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs), with advanced NSCLC harboring EGFR mutations, were enrolled. Erlotinib was given at 150 mg once daily until disease progression. The primary end point was objective response rate (ORR). Plasma trough levels of erlotinib were measured on Days 2 (D2) and 8 (D8) by high-performance liquid chromatography. Results: In total, 29 patients were enrolled from September 2008 to January 2011. ORR was 61.5 % (95 % confidence interval [CI] 40.57-79.8) of 26 assessable patients. The median progression-free survival (PFS) and overall survival (OS) were 6.3 months and 16.9 months, respectively. Skin rash was observed in 24 patients, mostly at grade 1 or 2. Grade 2 pneumonitis was observed in one patient. We collected blood samples from 16 patients. The median PFS of the high and low D8/D2 ratio group was 11.2 months and 5.7 months, respectively (p = 0.044, hazard ratio = 0.301, 95 % CI 0.094-0.968). Conclusion: Erlotinib showed an ORR comparable to that seen in previous studies for patients with NSCLC harboring EGFR mutations, although response, the primary end point, did not reach the predetermined threshold level. The D8/D2 ratio of erlotinib plasma trough levels might be a predictive factor for PFS
Regulation of MicroRNA Biogenesis: A miRiad of mechanisms
microRNAs are small, non-coding RNAs that influence diverse biological functions through the repression of target genes during normal development and pathological responses. Widespread use of microRNA arrays to profile microRNA expression has indicated that the levels of many microRNAs are altered during development and disease. These findings have prompted a great deal of investigation into the mechanism and function of microRNA-mediated repression. However, the mechanisms which govern the regulation of microRNA biogenesis and activity are just beginning to be uncovered. Following transcription, mature microRNA are generated through a series of coordinated processing events mediated by large protein complexes. It is increasingly clear that microRNA biogenesis does not proceed in a 'one-size-fits-all' manner. Rather, individual classes of microRNAs are differentially regulated through the association of regulatory factors with the core microRNA biogenesis machinery. Here, we review the regulation of microRNA biogenesis and activity, with particular focus on mechanisms of post-transcriptional control. Further understanding of the regulation of microRNA biogenesis and activity will undoubtedly provide important insights into normal development as well as pathological conditions such as cardiovascular disease and cancer
Regulation of microRNA biogenesis and turnover by animals and their viruses
Item does not contain fulltextMicroRNAs (miRNAs) are a ubiquitous component of gene regulatory networks that modulate the precise amounts of proteins expressed in a cell. Despite their small size, miRNA genes contain various recognition elements that enable specificity in when, where and to what extent they are expressed. The importance of precise control of miRNA expression is underscored by functional studies in model organisms and by the association between miRNA mis-expression and disease. In the last decade, identification of the pathways by which miRNAs are produced, matured and turned-over has revealed many aspects of their biogenesis that are subject to regulation. Studies in viral systems have revealed a range of mechanisms by which viruses target these pathways through viral proteins or non-coding RNAs in order to regulate cellular gene expression. In parallel, a field of study has evolved around the activation and suppression of antiviral RNA interference (RNAi) by viruses. Virus encoded suppressors of RNAi can impact miRNA biogenesis in cases where miRNA and small interfering RNA pathways converge. Here we review the literature on the mechanisms by which miRNA biogenesis and turnover are regulated in animals and the diverse strategies that viruses use to subvert or inhibit these processes
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