86 research outputs found
Sub-GHz LPWAN network coexistence, management and virtualization : an overview and open research challenges
The IoT domain is characterized by many applications that require low-bandwidth communications over a long range, at a low cost and at low power. Low power wide area networks (LPWANs) fulfill these requirements by using sub-GHz radio frequencies (typically 433 or 868 MHz) with typical transmission ranges in the order of 1 up to 50 km. As a result, a single base station can cover large areas and can support high numbers of connected devices (> 1000 per base station). Notorious initiatives in this domain are LoRa, Sigfox and the upcoming IEEE 802.11ah (or "HaLow") standard. Although these new technologies have the potential to significantly impact many IoT deployments, the current market is very fragmented and many challenges exists related to deployment, scalability, management and coexistence aspects, making adoption of these technologies difficult for many companies. To remedy this, this paper proposes a conceptual framework to improve the performance of LPWAN networks through in-network optimization, cross-technology coexistence and cooperation and virtualization of management functions. In addition, the paper gives an overview of state of the art solutions and identifies open challenges for each of these aspects
Reconstruction Mechanism of FCC Transition-Metal (001) Surfaces
The reconstruction mechanism of (001) fcc transition metal surfaces is
investigated using a full-potential all-electron electronic structure method
within density-functional theory. Total-energy supercell calculations confirm
the experimental finding that a close-packed quasi-hexagonal overlayer
reconstruction is possible for the late 5-metals Ir, Pt, and Au, while it is
disfavoured in the isovalent 4 metals (Rh, Pd, Ag). The reconstructive
behaviour is driven by the tensile surface stress of the unreconstructed
surfaces; the stress is significantly larger in the 5 metals than in 4
ones, and only in the former case it overcomes the substrate resistance to the
required geometric rearrangement. It is shown that the surface stress for these
systems is due to charge depletion from the surface layer, and that the
cause of the 4th-to-5th row stress difference is the importance of relativistic
effects in the 5 series.Comment: RevTeX 3.0, 12 pages, 1 PostScript figure available upon request] 23
May 199
AURORA : bariatric surgery registration in women of reproductive age : a multicenter prospective cohort study
Background: The expansion of the obesity epidemic is accompanied with an increase in bariatric procedures, in particular in women of reproductive age. The weight loss induced by the surgery is believed to reverse the negative impact of overweight and obesity on female reproduction, however, research is limited to in particular retrospective cohort studies and a growing number of small case-series and case-(control) studies.
Methods/design: AURORA is a multicenter prospective cohort study. The main objective is to collect long-term data on reproductive outcomes before and after bariatric surgery and in a subsequent pregnancy. Women aged 18-45 years are invited to participate at 4 possible inclusion moments: 1) before surgery, 2) after surgery, 3) before 15 weeks of pregnancy and 4) in the immediate postpartum period (day 3-4). Depending on the time of inclusion, data are collected before surgery (T1), 3 weeks and 3, 6, 12 or x months after surgery (T2-T5) and during the first, second and third trimester of pregnancy (T6-T8), at delivery (T9) and 6 weeks and 6 months after delivery (T10-T11). Online questionnaires are send on the different measuring moments. Data are collected on contraception, menstrual cycle, sexuality, intention of becoming pregnant, diet, physical activity, lifestyle, psycho-social characteristics and dietary supplement intake. Fasting blood samples determine levels of vitamin A, D, E, K, B-1, B-12 and folate, albumin, total protein, coagulation parameters, magnesium, calcium, zinc and glucose. Participants are weighted every measuring moment. Fetal ultrasounds and pregnancy course and complications are reported every trimester of pregnancy. Breastfeeding is recorded and breast milk composition in the postpartum period is studied.
Discussion: AURORA is a multicenter prospective cohort study extensively monitoring women before undergoing bariatric surgery until a subsequent pregnancy and postpartum period
Association of Adipose tissue inflammation with histologic severity of nonalcoholic fatty liver disease
BACKGROUND & AIMS : The prevalence of nonalcoholic fatty
liver disease (NAFLD) has increased with the obesity pandemic.
We analyzed the transcriptional profiles of subcutaneous adipose
tissue (SAT) and visceral adipose tissue (VAT), and phenotypes
and functional characteristics of adipocyte tissue
macrophages (ATMs), in obese patients undergoing bariatric
surgery. METHODS : We collected anthropometric data; plasma
samples; and SAT, VAT, and liver tissues from 113 obese patients
undergoing bariatric surgery at academic hospitals in
Europe (Antwerp and Leuven) and South Africa. Based on
clinical and histologic features, patients were assigned to the
following groups: obese, NAFLD, nonalcoholic steatohepatitis
(NASH), or NASH with fibrosis. Microarray analyses were performed
to identify genes expressed differentially among groups.
We measured levels of cytokines and chemokines in plasma
samples and levels of RNAs in adipose tissues by quantitative
reverse-transcription polymerase chain reaction. ATMs were
isolated from patients and 13 lean individuals undergoing
cholecystectomy (controls), analyzed by flow cytometry, and
cultured; immunophenotypes and levels of cytokines and chemokines
in supernatants were determined. RESULTS : We
observed increased expression of genes that regulate inflammation
in adipose tissues from patients with NAFLD and NASH;
expression of these genes increased as disease progressed from
NAFLD to NASH. We found 111 genes associated with inflammation
that were expressed differentially between VAT and
SAT. Serum levels of interleukin 8, chemokine (C-C motif)
ligand 3, and tumor necrosis factor-a correlated with liver
inflammation and NAFLD activity score. We developed 2
models that could be used to determine patients’ liver histology
based on gene expression in VAT and SAT. Flow cytometry
showed increased proportions of CD11cĂľCD206Ăľ and CCR2Ăľ
macrophages in VAT from patients with NASH, and supernatants
of cultured macrophages had increased levels of cytokines
and chemokines compared with controls. CONCLUSIONS : VAT
and SAT from patients with NAFLD and NASH have an
increased expression of genes that regulate inflammation, and
ATM produce increased levels of inflammatory cytokines,
compared with adipose tissues from controls. We identified an expression profile of 5 genes in SAT that accurately predict
liver histology in these patients. Transcript profiling: accession
numbers: GSE58979 and GSE59045.Schalk van der Merwe, Chantal Mathieu, Frederik Nevens, David Cassiman, and Sven Francque are recipients of the Flanders fund for scientific research
(FWO klinisch mandaat), and Hannelie Korf is a recipient of the FWO postdoctoral mandate. Research at the Department of Endocrinology, Diabetology
and Metabolism and the Department of Gastroenterology and Hepatology of the Antwerp University Hospital (Belgium) was supported by the European
Union: FP6 (HEPADIP contract LSHM-CT-2005-018734) and FP7-HEALTH (RESOLVE no. 305707). Supported by a fellowship from the South African
Gastroenterology Association and a scholarship from the European Association for the Study of the Liver (J.d.P.). This research also was supported by a
research grant from the Gastro foundation of South Africa. The authors specifically acknowledge the support of Dr. Chris Kassianides. Also funded in part
by a grant from the Deutsche Forschungsgemeinschaft DFG-SFB 1052/1: Obesity Mechanisms (projects A04) and by the Helmholtz Alliance Imaging and
Curing Environmental Metabolic Disease through the Initiative and Networking Fund of the Helmholtz Association (M.G.).http://www.journals.elsevier.com/gastroenterology2016-09-30hb2016Internal Medicin
Interleukin-1 Receptor-Associated Kinase-3 Is a Key Inhibitor of Inflammation in Obesity and Metabolic Syndrome
BACKGROUND: Visceral obesity is associated with the rising incidence of type 2 diabetes and metabolic syndrome. Low-grade chronic inflammation and oxidative stress synergize in obesity and obesity-induced disorders. OBJECTIVE: We searched a cluster of molecules that support interactions between these stress conditions in monocytes. METHODS: RNA expressions in blood monocytes of two independent cohorts comprising 21 and 102 obese persons and 46 age-matched controls were determined by microarray and independently validated by quantitative RT-PCR analysis. The effect of three-month weight loss after bariatric surgery was determined. The effect of RNA silencing on inflammation and oxidative stress was studied in human monocytic THP-1 cells. RESULTS: Interleukin-1 receptor-associated kinase-3 (IRAK3), key inhibitor of IRAK/NFÎşB-mediated chronic inflammation, is downregulated in monocytes of obese persons. Low IRAK3 was associated with high superoxide dismutase-2 (SOD2), a marker of mitochondrial oxidative stress. A comparable expression profile was also detected in visceral adipose tissue of the same obese subjects. Low IRAK3 and high SOD2 was associated with a high prevalence of metabolic syndrome (odds ratio: 9.3; sensitivity: 91%; specificity: 77%). By comparison, the odds ratio of high-sensitivity C-reactive protein, a widely used marker of systemic inflammation, was 4.3 (sensitivity: 69%; specificity: 66%). Weight loss was associated with an increase in IRAK3 and a decrease in SOD2, in association with a lowering of systemic inflammation and a decreasing number of metabolic syndrome components. We identified the increase in reactive oxygen species in combination with obesity-associated low adiponectin and high glucose and interleukin-6 as cause of the decrease in IRAK3 in THP-1 cells in vitro. CONCLUSION: IRAK3 is a key inhibitor of inflammation in association with obesity and metabolic syndrome. Our data warrant further evaluation of IRAK3 as a diagnostic and prognostic marker, and as a target for intervention
Laparoscopy for primary and secondary bariatric procedures
Recently obesity has been defined as a disease and has turned bariatric surgery into a part of a chronic illness management. Obesity induces several comorbidities leading to cardiovascular disease and mortality. The effects of bariatric surgery on these comorbidities used to be classified as weight-loss induced. However bariatric surgery has recently been termed metabolic surgery because of the suspected direct, weight loss independent effect of bariatric procedures on the physiopathological mechanisms causing excess fat storage and insulin resistance. This review describes the standard procedures commonly performed and their specific outcomes on metabolic diseases in order to work towards more patient tailored treatment of obesity and to reduce side effects. Furthermore this review focuses on gaps in understanding the pathogenesis of obesity and its treatment with bariatric surgery. Surgery failures as well as new techniques are discussed and evaluated.publisher: Elsevier
articletitle: Laparoscopy for primary and secondary bariatric procedures
journaltitle: Best Practice & Research Clinical Gastroenterology
articlelink: http://dx.doi.org/10.1016/j.bpg.2013.11.013
content_type: article
copyright: Copyright © 2013 Elsevier Ltd. All rights reserved.status: publishe
Esophageal Squamous Cell Carcinoma After Adjustable Gastric Banding
The prevalence of morbid obesity has been increasing worldwide. Therefore, multiple laparoscopic adjustable gastric bandings (LAGBs) have been placed in Belgium in the nineties. The procedure was considered as minimal invasive with low morbidity rates. However, some publication cases suggest a possible association between LAGB and the onset of an esophageal cancer. We present a case of a 49-year-old female who consulted for dysphagia, epigastric pain, and anorexia 17Â years after LAGB. An esophageal squamous cell carcinoma was diagnosed in the distal esophagus, close to the lap band. The diagnostic value of the performed contrast swallow study seemed limited. We suggest that a routinely gastroscopic evaluation in the long-term follow-up after LAGB should be strived for in patients presenting with late-onset dysphagia.status: publishe
Gastrointestinal stromal tumour (GIST) arising in a colonic duplication cyst: case report
status: publishe
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