674 research outputs found
A class of plane symmetric perfect-fluid cosmologies with a Kasner-like singularity
We prove the existence of a class of plane symmetric perfect-fluid
cosmologies with a (-1/3, 2/3, 2/3) Kasner-like singularity. These solutions of
the Einstein equations depend on two smooth functions of one space coordinate.
They are constructed by solving a symmetric hyperbolic system of Fuchsian
equations.Comment: LaTeX, 15 pages, no figures, to appear in CQG, correction to
existence proo
On the Nature of Singularities in Plane Symmetric Scalar Field Cosmologies
The nature of the initial singularity in spatially compact plane symmetric
scalar field cosmologies is investigated. It is shown that this singularity is
crushing and velocity dominated and that the Kretschmann scalar diverges
uniformly as it is approached. The last fact means in particular that a maximal
globally hyperbolic spacetime in this class cannot be extended towards the past
through a Cauchy horizon. A subclass of these spacetimes is identified for
which the singularity is isotropic.Comment: 7 pages, MPA-AR-94-
Global well-posedness of the Kirchhoff equation and Kirchhoff systems
This article is devoted to review the known results on global well-posedness
for the Cauchy problem to the Kirchhoff equation and Kirchhoff systems with
small data. Similar results will be obtained for the initial-boundary value
problems in exterior domains with compact boundary. Also, the known results on
large data problems will be reviewed together with open problems.Comment: arXiv admin note: text overlap with arXiv:1211.300
Peroxisome Proliferator-Activated Receptor alpha (PPAR alpha) down-regulation in cystic fibrosis lymphocytes
Background: PPARs exhibit anti-inflammatory capacities and are potential modulators of the inflammatory response. We hypothesized that their expression and/or function may be altered in cystic fibrosis (CF), a disorder characterized by an excessive host inflammatory response.
Methods: PPARα, β and γ mRNA levels were measured in peripheral blood cells of CF patients and healthy subjects via RT-PCR. PPARα protein expression and subcellular localization was determined via western blot and immunofluorescence, respectively. The activity of PPARα was analyzed by gel shift assay.
Results: In lymphocytes, the expression of PPARα mRNA, but not of PPARβ, was reduced (-37%; p < 0.002) in CF patients compared with healthy persons and was therefore further analyzed. A similar reduction of PPARα was observed at protein level (-26%; p < 0.05). The transcription factor was mainly expressed in the cytosol of lymphocytes, with low expression in the nucleus. Moreover, DNA binding activity of the transcription factor was 36% less in lymphocytes of patients (p < 0.01). For PPARα and PPARβ mRNA expression in monocytes and neutrophils, no significant differences were observed between CF patients and healthy persons. In all cells, PPARγ mRNA levels were below the detection limit.
Conclusion: Lymphocytes are important regulators of the inflammatory response by releasing cytokines and antibodies. The diminished lymphocytic expression and activity of PPARα may therefore contribute to the inflammatory processes that are observed in CF
PPAR Alpha Regulation of the Immune Response and Autoimmune Encephalomyelitis
PPARs are members of the steroid hormone nuclear receptor superfamily and play an important role in the regulation of lipid metabolism, energy balance, artherosclerosis and glucose control. Recent studies suggest that they play an important role in regulating inflammation. This review will focus on PPAR-α regulation of the immune response. We describe how PPAR-α regulates differentiation of T cells by transactivation and/or interaction with other transcription factors. Moreover, PPAR-α agonists have been shown to ameliorate experimental autoimmune encephalomyelitis (EAE) in mice, suggesting that they could provide a therapy for human autoimmune diseases such as multiple sclerosis
Multi-centre parallel arm randomised controlled trial to assess the effectiveness and cost-effectiveness of a group-based cognitive behavioural approach to managing fatigue in people with multiple sclerosis
Abstract (provisional)
Background
Fatigue is one of the most commonly reported and debilitating symptoms of multiple sclerosis (MS); approximately two-thirds of people with MS consider it to be one of their three most troubling symptoms. It may limit or prevent participation in everyday activities, work, leisure, and social pursuits, reduce psychological well-being and is one of the key precipitants of early retirement. Energy effectiveness approaches have been shown to be effective in reducing MS-fatigue, increasing self-efficacy and improving quality of life. Cognitive behavioural approaches have been found to be effective for managing fatigue in other conditions, such as chronic fatigue syndrome, and more recently, in MS. The aim of this pragmatic trial is to evaluate the clinical and cost-effectiveness of a recently developed group-based fatigue management intervention (that blends cognitive behavioural and energy effectiveness approaches) compared with current local practice.
Methods
This is a multi-centre parallel arm block-randomised controlled trial (RCT) of a six session group-based fatigue management intervention, delivered by health professionals, compared with current local practice. 180 consenting adults with a confirmed diagnosis of MS and significant fatigue levels, recruited via secondary/primary care or newsletters/websites, will be randomised to receive the fatigue management intervention or current local practice. An economic evaluation will be undertaken alongside the trial. Primary outcomes are fatigue severity, self-efficacy and disease-specific quality of life. Secondary outcomes include fatigue impact, general quality of life, mood, activity patterns, and cost-effectiveness. Outcomes in those receiving the fatigue management intervention will be measured 1 week prior to, and 1, 4, and 12 months after the intervention (and at equivalent times in those receiving current local practice). A qualitative component will examine what aspects of the fatigue management intervention participants found helpful/unhelpful and barriers to change.
Discussion
This trial is the fourth stage of a research programme that has followed the Medical Research Council guidance for developing and evaluating complex interventions. What makes the intervention unique is that it blends cognitive behavioural and energy effectiveness approaches. A potential strength of the intervention is that it could be integrated into existing service delivery models as it has been designed to be delivered by staff already working with people with MS. Service users will be involved throughout this research. Trial registration: Current Controlled Trials ISRCTN7651747
The Effects of Serotonin Receptor Antagonists on Contraction and Relaxation Responses Induced by Electrical Stimulation in the Rat Small Intestine
Background: The main source of 5-HT in body is in enterchromafin cells of intestine, different studies mentioned different roles for endogenous 5-HT and receptors involved and it is not clearified the mechanism of action of endogenous 5-HT.
Objectives: To study the role of endogenous 5-HT on modulation of contraction and relaxation responses induced by electrical field stimulation (EFS) in different regions of the rat intestine.
Materials and Methods: Segments taken from the rat duodenum, jejunum, mid and terminal ileum were vertically mounted, connected to a transducer and exposed to EFS with different frequencies in the absence and presence of various inhibitors of enteric mediators i. e. specific 5-HT receptor antagonists.
Results: EFS-induced responses were sensitive to TTX and partly to atropine, indicating a major neuronal involvement and a cholinergic system. Pre-treatment with WAY100635 (a 5-HT1A receptor antagonist) and granisetron up to 10.0 µM, GR113808 (a 5-HT4 receptor antagonist), methysergide and ritanserin up to 1.0 µM, failed to modify responses to EFS inall examined tissues. In the presence of SB258585 1.0 µM (a 5-HT6 receptor antagonist) there was a trend to enhance contraction in the proximal part of the intestine and reduce contraction in the distal part. Pre-treatment with SB269970A 1.0 µM (5-HT7 receptor antagonist) induced a greater contractile response to EFS at 0.4 Hz only in the duodenum.
Conclusions: The application of 5-HT1A, 5-HT2, 5-HT3, 5-HT4, 5-HT6 and 5-HT7 receptor antagonists, applied at concentrations lower than 1.0 µM did not modify the EFS-induced contraction and relaxation responses, whichsuggests the unlikely involvement of endogenous 5-HT in mediating responses to EFS in the described test conditions.
Keywords: Electric Stimulation Therapy; Serotonin 5-HT1 Receptor Antagonists; Intestine, Smal
Regulation of Immune Responses and Autoimmune Encephalomyelitis by PPARs
PPARs are members of the steroid hormone nuclear receptor superfamily and play an important role in regulating inflammation as well as lipid metabolism. The PPAR subfamily has been defined as PPARα, PPARβ/δ, and PPARγ, each with different ligands, target genes, and biological roles. PPARs regulate the expression of target inflammatory genes through mechanisms involving both transactivation and transrepression. The anti-inflammatory properties of PPAR agonists have led to the investigation of PPAR functions in regulating autoimmune encephalomyelitis. This paper will summarize some of the general mechanisms by which PPARs regulate inflammatory gene expression and focus on the recent advances of PPAR regulation of autoimmune encephalomyelitis
Multiple Sclerosis Followed by Neuromyelitis Optica Spectrum Disorder: From the National Multiple Sclerosis Society Case Conference Proceedings
A woman presented at age 18 years with partial myelitis and diplopia and experienced multiple subsequent relapses. Her MRI demonstrated T2 abnormalities characteristic of multiple sclerosis (MS) (white matter ovoid lesions and Dawson fingers), and CSF demonstrated an elevated IgG index and oligoclonal bands restricted to the CSF. Diagnosed with clinically definite relapsing-remitting MS, she was treated with various MS disease-modifying therapies and eventually began experiencing secondary progression. At age 57 years, she developed an acute longitudinally extensive transverse myelitis and was found to have AQP4 antibodies by cell-based assay. Our analysis of the clinical course, radiographic findings, molecular diagnostic methods, and treatment response characteristics support the hypothesis that our patient most likely had 2 CNS inflammatory disorders: MS, which manifested as a teenager, and neuromyelitis optica spectrum disorder, which evolved in her sixth decade of life. This case emphasizes a key principle in neurology practice, which is to reconsider whether the original working diagnosis remains tenable, especially when confronted with evidence (clinical and/or paraclinical) that raises the possibility of a distinctively different disorder
- …
