232 research outputs found
Zero mode in the time-dependent symmetry breaking of theory
We apply the quartic exponential variational approximation to the symmetry
breaking phenomena of scalar field in three and four dimensions. We calculate
effective potential and effective action for the time-dependent system by
separating the zero mode from other non-zero modes of the scalar field and
treating the zero mode quantum mechanically. It is shown that the quantum
mechanical properties of the zero mode play a non-trivial role in the symmetry
breaking of the scalar theory.Comment: 10 pages, 3 figure
New Asymptotic Expanstion Method for the Wheeler-DeWitt Equation
A new asymptotic expansion method is developed to separate the Wheeler-DeWitt
equation into the time-dependent Schr\"{o}dinger equation for a matter field
and the Einstein-Hamilton-Jacobi equation for the gravitational field including
the quantum back-reaction of the matter field. In particular, the nonadiabatic
basis of the generalized invariant for the matter field Hamiltonian separates
the Wheeler-DeWitt equation completely in the asymptotic limit of
approaching infinity. The higher order quantum corrections of the gravity to
the matter field are found. The new asymptotic expansion method is valid
throughout all regions of superspace compared with other expansion methods with
a certain limited region of validity. We apply the new asymptotic expansion
method to the minimal FRW universe.Comment: 24 pages of Latex file, revte
Kidney Transplantation in Sensitized Recipients; A Single Center Experience
A successful transplantation, across a positive crossmatch barrier, is one of the most persistent long-standing problems in the field of kidney transplant medicine. The aim of this study was to describe seven consecutive living renal transplantations in recipients with positive crossmatch for donors or positive for donor specific antibodies (DSAs). A preconditioning regimen including plasmapheresis and intravenous immunoglobulin was delivered three times a week until the crossmatch and/or DSAs became negative. Mycophenolate mofetil and tacrolimus were started two days before the plasmapheresis. The protocol was modified to include administration of anti-CD 20 antibody (rituximab, 375 mg/m2) from the patient number 3 through the patient number 7. All seven patients achieved negative conversion of the crossmatch or DSAs, and the kidney transplantations were successfully performed in all cases. Acute cellular rejection occurred in two patients, which were subclinical and controlled with high dose steroid treatment. Antibody-mediated rejection occurred in one patient, which was easily reversed with plasmapheresis. All recipients attained normal graft function during the 7-24 months of follow up. Our study suggests that sensitized patients can be transplanted successfully with desensitization pretreatment
Genetic Predisposition of Donors Affects the Allograft Outcome in Kidney Transplantation; Polymorphisms of Stromal-Derived Factor-1 and CXC Receptor 4
Genetic interaction between donor and recipient may dictate the impending
responses after transplantation. In this study, we evaluated the role of the
genetic predispositions of stromal-derived factor-1 (SDF1) [rs1801157
(G>A)] and CXC receptor 4 (CXCR4) [rs2228014 (C>T)] on
renal allograft outcomes. A total of 335 pairs of recipients and donors were
enrolled. Biopsy-proven acute rejection (BPAR) and long-term graft survival were
traced. Despite similar allele frequencies between donors and recipients, minor
allele of SDF1 rs1801157 (GA+AA) from donor, not from recipients, has a
protective effect on the development of BPAR compared to wild type donor (GG)
(P = 0.005). Adjustment for multiple
covariates did not affect this result (odds ratio 0.39, 95% C.I
0.20–0.76, P = 0.006). CXCR4
rs2228014 polymorphisms from donor or recipient did not affect the incidence of
acute rejection. SDF1 was differentially expressed in renal tubular epithelium
with acute rejection according to genetic variations of donor rs1801157 showing
higher expressions in the grafts from GG donors. Contrary to the development of
BPAR, the presence of minor allele rs1801157 A, especially homozygocity,
predisposed poor graft survival
(P = 0.001). This association was
significant after adjusting for several risk factors (hazard ratio 3.01;
95% C.I = 1.19–7.60;
P = 0.020). The allelic variation of
recipients, however, was not associated with graft loss. A donor-derived genetic
polymorphism of SDF1 has influenced the graft outcome. Thus, the genetic
predisposition of donor should be carefully considered in transplantation
Control of Neural Stem Cell Survival by Electroactive Polymer Substrates
Stem cell function is regulated by intrinsic as well as microenvironmental factors, including chemical and mechanical signals. Conducting polymer-based cell culture substrates provide a powerful tool to control both chemical and physical stimuli sensed by stem cells. Here we show that polypyrrole (PPy), a commonly used conducting polymer, can be tailored to modulate survival and maintenance of rat fetal neural stem cells (NSCs). NSCs cultured on PPy substrates containing different counter ions, dodecylbenzenesulfonate (DBS), tosylate (TsO), perchlorate (ClO4) and chloride (Cl), showed a distinct correlation between PPy counter ion and cell viability. Specifically, NSC viability was high on PPy(DBS) but low on PPy containing TsO, ClO4 and Cl. On PPy(DBS), NSC proliferation and differentiation was comparable to standard NSC culture on tissue culture polystyrene. Electrical reduction of PPy(DBS) created a switch for neural stem cell viability, with widespread cell death upon polymer reduction. Coating the PPy(DBS) films with a gel layer composed of a basement membrane matrix efficiently prevented loss of cell viability upon polymer reduction. Here we have defined conditions for the biocompatibility of PPy substrates with NSC culture, critical for the development of devices based on conducting polymers interfacing with NSCs
Toxoplasma gondii Infection in the Brain Inhibits Neuronal Degeneration and Learning and Memory Impairments in a Murine Model of Alzheimer's Disease
Immunosuppression is a characteristic feature of Toxoplasma gondii-infected murine hosts. The present study aimed to determine the effect of the immunosuppression induced by T. gondii infection on the pathogenesis and progression of Alzheimer's disease (AD) in Tg2576 AD mice. Mice were infected with a cyst-forming strain (ME49) of T. gondii, and levels of inflammatory mediators (IFN-γ and nitric oxide), anti-inflammatory cytokines (IL-10 and TGF-β), neuronal damage, and β-amyloid plaque deposition were examined in brain tissues and/or in BV-2 microglial cells. In addition, behavioral tests, including the water maze and Y-maze tests, were performed on T. gondii-infected and uninfected Tg2576 mice. Results revealed that whereas the level of IFN-γ was unchanged, the levels of anti-inflammatory cytokines were significantly higher in T. gondii-infected mice than in uninfected mice, and in BV-2 cells treated with T. gondii lysate antigen. Furthermore, nitrite production from primary cultured brain microglial cells and BV-2 cells was reduced by the addition of T. gondii lysate antigen (TLA), and β-amyloid plaque deposition in the cortex and hippocampus of Tg2576 mouse brains was remarkably lower in T. gondii-infected AD mice than in uninfected controls. In addition, water maze and Y-maze test results revealed retarded cognitive capacities in uninfected mice as compared with infected mice. These findings demonstrate the favorable effects of the immunosuppression induced by T. gondii infection on the pathogenesis and progression of AD in Tg2576 mice
The Cosmic Infrared Background Experiment (CIBER): The Wide-Field Imagers
We have developed and characterized an imaging instrument to measure the
spatial properties of the diffuse near-infrared extragalactic background light
in a search for fluctuations from z > 6 galaxies during the epoch of
reionization. The instrument is part of the Cosmic Infrared Background
Experiment (CIBER), designed to observe the extragalactic background light
above the Earth's atmosphere during a suborbital sounding rocket flight. The
imaging instrument incorporates a 2x2 degree field of view, to measure
fluctuations over the predicted peak of the spatial power spectrum at 10
arcminutes, and 7"x7" pixels, to remove lower redshift galaxies to a depth
sufficient to reduce the low-redshift galaxy clustering foreground below
instrumental sensitivity. The imaging instrument employs two cameras with
\Delta \lambda / \lambda ~0.5 bandpasses centered at 1.1 and 1.6 microns to
spectrally discriminate reionization extragalactic background fluctuations from
local foreground fluctuations. CIBER operates at wavelengths where the
electromagnetic spectrum of the reionization extragalactic background is
thought to peak, and complements fluctuations measurements by AKARI and Spitzer
at longer wavelengths. We have characterized the instrument in the laboratory,
including measurements of the sensitivity, flat-field response, stray light
performance, and noise properties. Several modifications were made to the
instrument following a first flight in 2009 February. The instrument performed
to specifications in subsequent flights in 2010 July and 2012 March, and the
scientific data are now being analyzed.Comment: 16 Pages, 16 figures, submitted to ApJS February 13 2012; accepted
June 20 2012 as part of CIBER Instrument Special Issu
Radiosensitizing potential of the selective cyclooygenase-2 (COX-2) inhibitor meloxicam on human glioma cells
The COX-2 protein is frequently overexpressed in human malignant gliomas. This expression has been associated with their aggressive
growth characteristics and poor prognosis for patients. Targeting the COX-2 pathway might improve glioma therapy. In this
study, the effects of the selective COX-2 inhibitor meloxicam alone and in combination with irradiation were investigated
on human glioma cells in vitro. A panel of three glioma cell lines (D384, U87 and U251) was used in the experiments from which U87 cells expressed constitutive
COX-2. The response to meloxicam and irradiation (dose-range of 0–6 Gy) was determined by the clonogenic assay, cell proliferation
was evaluated by growth analysis and cell cycle distribution by FACS. 24–72 h exposure to 250–750 μM meloxicam resulted in
a time and dose dependent growth inhibition with an almost complete inhibition after 24 h for all cell lines. Exposure to
750 μM meloxicam for 24 h increased the fraction of cells in the radiosensitive G2/M cell cycle phase in D384 (18–27%) and U251 (17–41%) cells. 750 μM meloxicam resulted in radiosensitization of D384 (DMF:2.19)
and U87 (DMF:1.25) cells, but not U251 cells (DMF:1.08). The selective COX-2 inhibitor meloxicam exerted COX-2 independent
growth inhibition and radiosensitization of human glioma cells
The 'Harmonizing Optimal Strategy for Treatment of coronary artery stenosis - sAfety & effectiveneSS of drug-elUting stents & antiplatelet REgimen' (HOST-ASSURE) trial: study protocol for a randomized controlled trial
<p>Abstract</p> <p>Background</p> <p>Second-generation drug-eluting stents (DES) have raised the bar of clinical performance. These stents are mostly made from cobalt chromium alloy. A newer generation DES has been developed from platinum chromium alloy, but clinical data regarding the efficacy and safety of the platinum chromium-based everolimus-eluting stent (PtCr-EES) is limited, with no comparison data against the cobalt chromium-based zotarolimus-eluting stent (CoCr-ZES). In addition, an antiplatelet regimen is an integral component of medical therapy after percutaneous coronary intervention (PCI). A 1-week duration of doubling the dose of clopidogrel (double-dose antiplatelet therapy (DDAT)) was shown to improve outcome at 1 month compared with conventional dose in acute coronary syndrome (ACS) patients undergoing PCI. However in Asia, including Korea, the addition of cilostazol (triplet antiplatelet therapy (TAT)) is used more commonly than doubling the dose of clopidogrel in high-risk patients.</p> <p>Methods</p> <p>In the 'Harmonizing Optimal Strategy for Treatment of coronary artery stenosis - sAfety & effectiveneSS of drug-elUting stents & antiplatelet REgimen' (HOST-ASSURE) trial, approximately 3,750 patients are being prospectively and randomly assigned in a 2 × 2 factorial design according to the type of stent (PtCr-EES vs CoCr-ZES) and antiplatelet regimen (TAT vs DDAT). The first primary endpoint is target lesion failure at 1 year for the stent comparison, and the second primary endpoint is net clinical outcome at 1 month for comparison of antiplatelet therapy regimen.</p> <p>Discussion</p> <p>The HOST-ASSURE trial is the largest study yet performed to directly compare the efficacy and safety of the PtCr-EES versus CoCr-ZES in an 'all-comers' population. In addition, this study will also compare the clinical outcome of TAT versus DDAT for 1-month post PCI.</p> <p>Trial registration</p> <p>ClincalTrials.gov number <a href="http://www.clinicaltrials.gov/ct2/show/NCT01267734">NCT01267734</a>.</p
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