2,236 research outputs found
Primary Intestinal Lymphoma in Crohn's Disease: Minute Tumor with a Fatal Outcome
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75263/1/j.1572-0241.1992.tb02897.x.pd
Aberrant iron homeostasis, oxidative fiber enrichment, and activation of ketogenesis in muscle tissue of ISCU Myopathy patients
Phase separation due to quantum mechanical correlations
Can phase separation be induced by strong electron correlations? We present a
theorem that affirmatively answers this question in the Falicov-Kimball model
away from half-filling, for any dimension. In the ground state the itinerant
electrons are spatially separated from the classical particles.Comment: 4 pages, 1 figure. Note: text and figure unchanged, title was
misspelle
Gribov Problem for Gauge Theories: a Pedagogical Introduction
The functional-integral quantization of non-Abelian gauge theories is
affected by the Gribov problem at non-perturbative level: the requirement of
preserving the supplementary conditions under gauge transformations leads to a
non-linear differential equation, and the various solutions of such a
non-linear equation represent different gauge configurations known as Gribov
copies. Their occurrence (lack of global cross-sections from the point of view
of differential geometry) is called Gribov ambiguity, and is here presented
within the framework of a global approach to quantum field theory. We first
give a simple (standard) example for the SU(2) group and spherically symmetric
potentials, then we discuss this phenomenon in general relativity, and recent
developments, including lattice calculations.Comment: 24 pages, Revtex 4. In the revised version, a statement has been
amended on page 11, and References 14, 16 and 27 have been improve
Acute Loss of Iron-Sulfur Clusters Results in Metabolic Reprogramming and Generation of Lipid Droplets in Mammalian Cells
Ironâsulfur (Fe-S) clusters are ancient cofactors in cells and participate in diverse biochemical functions, including electron transfer and enzymatic catalysis. Although cell lines derived from individuals carrying mutations in the Fe-S cluster biogenesis pathway or siRNA-mediated knockdown of the Fe-S assembly components provide excellent models for investigating Fe-S cluster formation in mammalian cells, these experimental strategies focus on the consequences of prolonged impairment of Fe-S assembly. Here, we constructed and expressed dominantânegative variants of the primary Fe-S biogenesis scaffold protein ironâsulfur cluster assembly enzyme 2 (ISCU2) in human HEK293 cells. This approach enabled us to study the early metabolic reprogramming associated with loss of Fe-Sâcontaining proteins in several major cellular compartments. Using multiple metabolomics platforms, we observed a âŒ12-fold increase in intracellular citrate content in Fe-Sâdeficient cells, a surge that was due to loss of aconitase activity. The excess citrate was generated from glucose-derived acetyl-CoA, and global analysis of cellular lipids revealed that fatty acid biosynthesis increased markedly relative to cellular proliferation rates in Fe-Sâdeficient cells. We also observed intracellular lipid droplet accumulation in both acutely Fe-Sâdeficient cells and iron-starved cells. We conclude that deficient Fe-S biogenesis and acute iron deficiency rapidly increase cellular citrate concentrations, leading to fatty acid synthesis and cytosolic lipid droplet formation. Our findings uncover a potential cause of cellular steatosis in nonadipose tissues
Electron spin dynamics in quantum dots and related nanostructures due to hyperfine interaction with nuclei
We review and summarize recent theoretical and experimental work on electron
spin dynamics in quantum dots and related nanostructures due to hyperfine
interaction with surrounding nuclear spins. This topic is of particular
interest with respect to several proposals for quantum information processing
in solid state systems. Specifically, we investigate the hyperfine interaction
of an electron spin confined in a quantum dot in an s-type conduction band with
the nuclear spins in the dot. This interaction is proportional to the square
modulus of the electron wave function at the location of each nucleus leading
to an inhomogeneous coupling, i.e. nuclei in different locations are coupled
with different strength. In the case of an initially fully polarized nuclear
spin system an exact analytical solution for the spin dynamics can be found.
For not completely polarized nuclei, approximation-free results can only be
obtained numerically in sufficiently small systems. We compare these exact
results with findings from several approximation strategies.Comment: 26 pages, 9 figures. Topical Review to appear in J. Phys.: Condens.
Matte
Sex and adverse events of adjuvant chemotherapy in colon cancer: an analysis of 34,640 patients in the ACCENT database
BACKGROUND: Adjuvant chemotherapy is a standard treatment option for patients with stage III and high-risk stage II colon cancer. Sex is one of several factors responsible for the wide inter-patient variability in drug responses. Amalgamated data on the effect of sex on the toxicity of current standard adjuvant treatment for colorectal cancer are missing. METHODS: The objective of our study was to compare incidence and severity of major toxicities of fluoropyrimidine- (5FU or capecitabine) based adjuvant chemotherapy, with or without oxaliplatin, between male and female patients after curative surgery for colon cancer. Adult patients enrolled in 27 relevant randomized trials included in the ACCENT (Adjuvant Colon Cancer End Points) database, a large, multi-group, international data repository containing individual patient data, were included. Comparisons were conducted using logistic regression models (stratified by study and treatment arm) within each type of adjuvant chemotherapy (5FU, FOLFOX, capecitabine, CAPOX, and FOLFIRI). The following major toxicities were compared (grade III or IV and grade I-IV, according to National Cancer Institute Common Terminology Criteria [NCI-CTC] criteria, regardless of attribution): nausea, vomiting, nausea or vomiting, stomatitis, diarrhea, leukopenia, neutropenia, thrombocytopenia, anemia, and neuropathy (in patients treated with oxaliplatin). RESULTS: Data from 34â640 patients were analyzed. Statistically significant and clinically relevant differences in the occurrence of grade III or IV nonhematological {especially nausea (5FU: odds ratio [OR] = 2.33, 95% confidence interval [CI] = 1.90 to 2.87, P < .001; FOLFOX: OR = 2.34, 95% CI = 1.76 to 3.11, P < .001), vomiting (5FU: OR = 2.38, 95% CI = 1.86 to 3.04, P < .001; FOLFOX: OR = 2.00, 95% CI = 1.50 to 2.66, P < .001; CAPOX: OR = 2.32, 95% CI = 1.55 to 3.46, P < .001), and diarrhea (5FU: OR = 1.35, 95% CI = 1.21 to 1.51, P < .001; FOLFOX: OR = 1.60, 95% CI = 1.35 to 1.90, P < .001; FOLFIRI: OR = 1.57, 95% CI = 1.25 to 1.97, P < .001)} as well as hematological toxicities (neutropenia [5FU: OR = 1.55, 95% CI = 1.37 to 1.76, P < .001; FOLFOX: OR = 1.96, 95% CI = 1.71 to 2.25, P < .001; FOLFIRI: OR = 2.01, 95% CI = 1.66 to 2.43, P < .001; capecitabine: OR = 4.07, 95% CI = 1.84 to 8.99, P < .001] and leukopenia [5FU: OR = 1.74, 95% CI = 1.40 to 2.17, P < .001; FOLFIRI: OR = 1.75, 95% CI = 1.28 to 2.40, P < .001]) were observed, with women being consistently at increased risk. CONCLUSIONS: Our analysis confirms that women with colon cancer receiving adjuvant fluoropyrimidine-based chemotherapy are at increased risk of toxicity. Given the known sex differences in fluoropyrimidine pharmacokinetics, sex-specific dosing of fluoropyrimidines warrants further investigation
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Association studies of up to 1.2 million individuals yield new insights into the genetic etiology of tobacco and alcohol use.
Tobacco and alcohol use are leading causes of mortality that influence risk for many complex diseases and disorders1. They are heritable2,3 and etiologically related4,5 behaviors that have been resistant to gene discovery efforts6-11. In sample sizes up to 1.2âmillion individuals, we discovered 566 genetic variants in 406 loci associated with multiple stages of tobacco use (initiation, cessation, and heaviness) as well as alcohol use, with 150 loci evidencing pleiotropic association. Smoking phenotypes were positively genetically correlated with many health conditions, whereas alcohol use was negatively correlated with these conditions, such that increased genetic risk for alcohol use is associated with lower disease risk. We report evidence for the involvement of many systems in tobacco and alcohol use, including genes involved in nicotinic, dopaminergic, and glutamatergic neurotransmission. The results provide a solid starting point to evaluate the effects of these loci in model organisms and more precise substance use measures
Lung Function after the Minimal Invasive Pectus Excavatum Repair (Nuss Procedure)
Background The Nuss procedure was introduced at our center in 1999. The operation was mainly performed for cosmesis. Little information is available regarding the influence of this operation on lung function. Methods The aim of this study, a prospective analysis, was to analyze the effect of the Nuss procedure on lung function variables. Between 1999 and 2007 a total of 203 patients with pectus excavatum were treated with the Nuss procedure, of whom 145 (104 male, 41 female) were located at Emma Childrenâs Hospital. In the latter subset of consecutive patients, static lung function variables [total lung capacity (TLC), functional residual capacity (FRC), vital capacity (VC)] and dynamic lung function variables [forced expired volume in 1 s (FEV1), maximum expiratory flow (MEF50)] were performed using spirometry and body box measurements at four time points: prior to operation Some of these data were presented at the International Surgical Week
Defining a Minimum Set of Standardized Patient-centered Outcome Measures for Macular Degeneration
Purpose To define a minimum set of outcome measures for tracking, comparing, and improving macular degeneration care. Design Recommendations from a working group of international experts in macular degeneration outcomes registry development and patient advocates, facilitated by the International Consortium for Health Outcomes Measurement (ICHOM). Methods Modified Delphi technique, supported by structured teleconferences, followed by online surveys to drive consensus decisions. Potential outcomes were identified through literature review of outcomes collected in existing registries and reported in major clinical trials. Outcomes were refined by the working group and selected based on impact on patients, relationship to good clinical care, and feasibility of measurement in routine clinical practice. Results Standardized measurement of the following outcomes is recommended: visual functioning and quality of life (distance visual acuity, mobility and independence, emotional well-being, reading and accessing information); number of treatments; complications of treatment; and disease control. Proposed data collection sources include administrative data, clinical data during routine clinical visits, and patient-reported sources annually. Recording the following clinical characteristics is recommended to enable risk adjustment: age; sex; ethnicity; smoking status; baseline visual acuity in both eyes; type of macular degeneration; presence of geographic atrophy, subretinal fibrosis, or pigment epithelial detachment; previous macular degeneration treatment; ocular comorbidities. Conclusions The recommended minimum outcomes and pragmatic reporting standards should enable standardized, meaningful assessments and comparisons of macular degeneration treatment outcomes. Adoption could accelerate global improvements in standardized data gathering and reporting of patient-centered outcomes. This can facilitate informed decisions by patients and health care providers, plus allow long-term monitoring of aggregate data, ultimately improving understanding of disease progression and treatment responses
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