2,543 research outputs found
Bergman and Caratheodory metrics of the Kohn-Nirenberg domains
The Kohn-Nireberg domains are unbounded domains in the complex Euclidean
space of dimension 2 upon which many outstanding questions are yet to be
explored. The primary aim of this article is to demonstrate that the Bergman
and Caratheodory metrics of any Kohn-Nirenberg domains are positive and
complete.Comment: 11 page
Measuring IS Service Quality in the Context of the Service Quality-User Satisfaction Relationship
There is little research regarding the relationship between IS service quality and user satisfaction, the most frequently used surrogate for information systems success. The current study is designed to investigate three ways of measuring service quality (i.e., confirmation/disconfirmation, perception-only, and overall assessment) and shed light on the relationship between service quality and user satisfaction. The results imply that when managers try to measure service quality to improve their service, they have to be cautious in ruling out or selecting one way or another of measuring service quality. The current research also clearly shows that mangers have to take care of the service quality to enhance user satisfaction. The models and results are discussed
Schwannoma Mimicking Laryngocele
A schwannoma of the larynx is a rare benign tumor that usually presents as a submucosal mass in the pyriform sinus and the aryepiglottic space, and this type of schwannoma constitutes a diagnostic and therapeutic challenge for otolaryngologists. We present here two cases of supraglottic schwannomas that were misdiagnosed as laryngoceles. Both were excised through a lateral thyrotomy approach without a tracheostomy, and the laryngeal function was successfully maintained. We discuss the clinical and imaging findings and the management of this rare neoplasm with focusing on the differential diagnosis of laryngeal schwannoma and laryngocele. We also review the relevant medical literature
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Inhibition of cAMP/PKA Pathway Protects Optic Nerve Head Astrocytes against Oxidative Stress by Akt/Bax Phosphorylation-Mediated Mfn1/2 Oligomerization.
Glaucoma is characterized by a progressive optic nerve degeneration and retinal ganglion cell loss, but the underlying biological basis for the accompanying neurodegeneration is not known. Accumulating evidence indicates that structural and functional abnormalities of astrocytes within the optic nerve head (ONH) have a role in glaucomatous neurodegeneration. Here, we investigate the impact of activation of cyclic adenosine 3',5'-monophosphate (cAMP)/protein kinase A (PKA) pathway on mitochondrial dynamics of ONH astrocytes exposed to oxidative stress. ONH astrocytes showed a significant loss of astrocytic processes in the glial lamina of glaucomatous DBA/2J mice, accompanied by basement membrane thickening and collagen deposition in blood vessels and axonal degeneration. Serial block-face scanning electron microscopy data analysis demonstrated that numbers of total and branched mitochondria were significantly increased in ONH astrocytes, while mitochondrial length and volume density were significantly decreased. We found that hydrogen peroxide- (H2O2-) induced oxidative stress compromised not only mitochondrial bioenergetics by reducing the basal and maximal respiration but also balance of mitochondrial dynamics by decreasing dynamin-related protein 1 (Drp1) protein expression in rat ONH astrocytes. In contrast, elevated cAMP by dibutyryl-cAMP (dbcAMP) or isobutylmethylxanthine treatment significantly increased Drp1 protein expression in ONH astrocytes. Elevated cAMP exacerbated the impairment of mitochondrial dynamics and reduction of cell viability to oxidative stress in ONH astrocytes by decreasing optic atrophy type 1 (OPA1), and mitofusin (Mfn)1/2 protein expression. Following combined treatment with H2O2 and dbcAMP, PKA inhibition restored mitochondrial dynamics by increasing mitochondrial length and decreasing mitochondrial number, and this promoted cell viability in ONH astrocytes. Also, PKA inhibition significantly promoted Akt/Bax phosphorylation and Mfn1/2 oligomerization in ONH astrocytes. These results suggest that modulation of the cAMP/PKA signaling pathway may have therapeutic potential by activating Akt/Bax phosphorylation and promoting Mfn1/2 oligomerization in glaucomatous ONH astrocytes
Role of Transcription Factor Modifications in the Pathogenesis of Insulin Resistance
Non-alcoholic fatty liver disease (NAFLD) is characterized by fat accumulation in the liver not due to alcohol abuse. NAFLD is accompanied by variety of symptoms related to metabolic syndrome. Although the metabolic link between NAFLD and insulin resistance is not fully understood, it is clear that NAFLD is one of the main cause of insulin resistance. NAFLD is shown to affect the functions of other organs, including pancreas, adipose tissue, muscle and inflammatory systems. Currently efforts are being made to understand molecular mechanism of interrelationship between NAFLD and insulin resistance at the transcriptional level with specific focus on post-translational modification (PTM) of transcription factors. PTM of transcription factors plays a key role in controlling numerous biological events, including cellular energy metabolism, cell-cycle progression, and organ development. Cell type- and tissue-specific reversible modifications include lysine acetylation, methylation, ubiquitination, and SUMOylation. Moreover, phosphorylation and O-GlcNAcylation on serine and threonine residues have been shown to affect protein stability, subcellular distribution, DNA-binding affinity, and transcriptional activity. PTMs of transcription factors involved in insulin-sensitive tissues confer specific adaptive mechanisms in response to internal or external stimuli. Our understanding of the interplay between these modifications and their effects on transcriptional regulation is growing. Here, we summarize the diverse roles of PTMs in insulin-sensitive tissues and their involvement in the pathogenesis of insulin resistance
Origin of multi-level switching and telegraphic noise in organic nanocomposite memory devices.
The origin of negative differential resistance (NDR) and its derivative intermediate resistive states (IRSs) of nanocomposite memory systems have not been clearly analyzed for the past decade. To address this issue, we investigate the current fluctuations of organic nanocomposite memory devices with NDR and the IRSs under various temperature conditions. The 1/f noise scaling behaviors at various temperature conditions in the IRSs and telegraphic noise in NDR indicate the localized current pathways in the organic nanocomposite layers for each IRS. The clearly observed telegraphic noise with a long characteristic time in NDR at low temperature indicates that the localized current pathways for the IRSs are attributed to trapping/de-trapping at the deep trap levels in NDR. This study will be useful for the development and tuning of multi-bit storable organic nanocomposite memory device systems
Anti-Inflammatory Effects of Bangpungtongsung-San, a Traditional Herbal Prescription
Bangpungtongsung-san (BPTS), a traditional oriental herbal prescription, is widely used for expelling wind, draining heat, and providing general improvement to the immune system. In this study, we investigated the effects of BPTS on induction of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), proinflammatory cytokines, nuclear factor-kappa B (NF-κB), and mitogen-activated protein kinases (MAPKs) in lipopolysaccharide- (LPS- ) stimulated Raw 264.7 cells, and on paw edema in rats. At concentrations of 0.5, 0.75, and 1 mg/mL, treatment with BPTS inhibited levels of expression of LPS-induced NF-κB and MAPKs (ERK, JNK, and p38) as well as production of proinflammatory mediators, such as nitric oxide (NO), prostaglandin E2 (PGE2), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) by LPS. These results suggest that BPTS may exert anti-inflammatory effects via reduction of proinflammatory mediators, including NO, PGE2, TNF-α, and IL-6 through suppression of the signaling pathways of NF-κB and MAPKs in LPS-induced macrophages. In addition, using the carrageenan-induced paw edema assay, an antiedema effect of BPTS was observed in rats. These findings may provide scientific evidence validating the use of BPTS in treatment of patients with heat syndrome in Korean oriental medicine
Subclinical vascular inflammation in subjects with normal weight obesity and its association with body Fat: an 18 F-FDG-PET/CT study
BACKGROUND: Although body mass index (BMI) is the most widely accepted parameter for defining obesity, recent studies have indicated a unique set of patients who exhibit normal BMI and excess body fat (BF), which is termed as normal weight obesity (NWO). Increased BF is an established risk factor for atherosclerosis. However, it is unclear whether NWO subjects already have a higher degree of vascular inflammation compared to normal weight lean (NWL) subjects; moreover, the association of BF with vascular inflammation in normal weight subjects is largely unknown. METHODS: NWO and NWL subjects (n = 82 in each group) without any history of significant vascular disease were identified from a 3-year database of consecutively recruited patients undergoing (18) F-fluorodeoxyglucose positron emission tomography/computed tomography ((18) F-FDG-PET/CT) at a self-referred Healthcare Promotion Program. The degree of subclinical vascular inflammation was evaluated using the mean and maximum target-to-background ratios (TBRmean and TBRmax) of the carotid artery, which were measured by (18) F-FDG-PET/CT (a noninvasive tool for assessing vascular inflammation). RESULTS: We found that metabolically dysregulation was greater in NWO subjects than in NWL subjects, with a significantly higher blood pressure, higher fasting glucose level, and worse lipid profile. Moreover, NWO subjects exhibited higher TBR than NWL subjects (TBRmean: 1.33 ± 0.16 versus 1.45 ± 0.19, p < 0.001; TBRmax: 1.52 ± 0.23 versus 1.67 ± 0.25, p < 0.001). TBR was significantly associated with total BF (TBRmean: r = 0.267, p = 0.001; TBRmax: r = 0.289, p < 0.001), age (TBRmean: r = 0.170, p = 0.029; TBRmax: r = 0.165, p = 0.035), BMI (TBRmean: r = 0.184, p = 0.018; TBRmax: r = 0.206, p = 0.008), and fasting glucose level (TBRmean: r = 0.157, p = 0.044; TBRmax: r = 0.182, p = 0.020). In multiple linear regression analysis, BF was an independent determinant of TBRmean and TBRmax, after adjusting for age, BMI, and fasting glucose level (TBRmean: regression coefficient = 0.020, p = 0.008; TBRmax: regression coefficient = 0.028, p = 0.005). Compared to NWL, NWO was also independently associated with elevated TBRmax values, after adjusting for confounding factors (odds ratio = 2.887, 95% confidence interval 1.206–6.914, p = 0.017). CONCLUSIONS: NWO is associated with a higher degree of subclinical vascular inflammation, of which BF is a major contributing factor. These results warrant investigations for subclinical atherosclerosis in NWO patients
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