77 research outputs found
Ferromagnetism in nanoscale BiFeO3
A remarkably high saturation magnetization of ~0.4mu_B/Fe along with room
temperature ferromagnetic hysteresis loop has been observed in nanoscale (4-40
nm) multiferroic BiFeO_3 which in bulk form exhibits weak magnetization
(~0.02mu_B/Fe) and an antiferromagnetic order. The magnetic hysteresis loops,
however, exhibit exchange bias as well as vertical asymmetry which could be
because of spin pinning at the boundaries between ferromagnetic and
antiferromagnetic domains. Interestingly, like in bulk BiFeO_3, both the
calorimetric and dielectric permittivity data in nanoscale BiFeO_3 exhibit
characteristic features at the magnetic transition point. These features
establish formation of a true ferromagnetic-ferroelectric system with a
coupling between the respective order parameters in nanoscale BiFeO_3.Comment: 13 pages including 4 figures; pdf only; submitted to Appl. Phys. Let
Detecting matter effects in long baseline experiments
Experiments strongly suggest that the flavour mixing responsible for the
atmospheric neutrino anomaly is very close to being maximal. Thus, it is of
great theoretical as well as experimental importance to measure any possible
deviation from maximality. In this context, we reexamine the effects of matter
interactions in long baseline neutrino oscillation experiments. Contrary to
popular belief, the muon neutrino survival probability is shown to be quite
sensitive to matter effects. Moreover, for moderately long baselines, the
difference between the survival probilities for and is
shown to be large and sensitive to the deviation of from
maximality. Performing a realistic analysis, we demonstrate that a muon-storage
ring -source alongwith an iron calorimeter detector can measure such
deviations. (Contrary to recent claims, this is not so for the NuMI--{\sc
minos} experiment.) We also discuss the possible correlation in measuring
and in such experiment.Comment: 18 pages, LaTe
Large Non-perturbative Effects of Small \Delta m^2_{21}/\Delta m^2_{31} and \sin \theta_{13} on Neutrino Oscillation and CP Violation in Matter
In the framework of three generations, we consider the CP violation in
neutrino oscillation with matter effects. At first, we show that the
non-perturbative effects of two small parameters, \Delta m_{21}^2/\Delta
m_{31}^2 and \sin \theta_{13}, become more than 50% in certain ranges of energy
and baseline length. This means that the non-perturbative effects should be
considered in detailed analysis in the long baseline experiments. Next, we
propose a method to include these effects in approximate formulas for
oscillation probabilities. Assuming the two natural conditions,
\theta_{23}=45^\circ and the fact that the matter density is symmetric, a set
of approximate formulas, which involve the non-perturbative effects, has been
derived in all channels.Comment: 25 pages, 4 figures, version to appear in JHE
Apoptosis Inducing Effect of Plumbagin on Colonic Cancer Cells Depends on Expression of COX-2
Plumbagin, a quinonoid found in the plants of the Plumbaginaceae, possesses
medicinal properties. In this study we investigated the anti-proliferative and
apoptotic activity of plumbagin by using two human colonic cancer cell lines,
HT29 and HCT15. IC50 of Plumbagin for HCT15 and HT29 cells (22.5 µM and
62.5 µM, respectively) were significantly different. To study the response
of cancer cells during treatment strategies, cells were treated with two
different concentrations, 15 µM, 30 µM for HCT15 and 50 µM, 75
µM for HT29 cells. Though activation of NFκB, Caspases-3, elevated
levels of TNF-α, cytosolic Cytochrome C were seen in both
HCT15 cells HT29 treated with plumbagin, aberrant apoptosis with decreased level
of pEGFR, pAkt, pGsk-3β, PCNA and Cyclin D1was observed only in 15 µM
and 30 µM plumbagin treated HCT15 and 75 µM plumbagin treated HT29
cells. This suggests that plumbagin induces apoptosis in both HCT15 cells and
HT29 treated, whereas, proliferation was inhibited only in 15 µM and 30
µM plumbagin treated HCT15 and 75 µM plumbagin treated HT29 cells,
but not in 50 µM plumbagin treated HT29 cells. Expression of COX-2 was
decreased in 75 µM plumbagin treated HT29 cells when compared to 50
µM plumbagin treated HT29 cells, whereas HCT15 cells lack COX. Hence the
observed resistance to induction of apoptosis in 50 µM plumbagin treated
HT29 cells are attributed to the expression of COX-2. In conclusion, plumbagin
induces apoptosis in colonic cancer cells through TNF-α mediated pathway
depending on expression of COX-2 expression
Defining the Critical Hurdles in Cancer Immunotherapy
ABSTRACT: Scientific discoveries that provide strong evidence of antitumor effects in preclinical models often encounter significant delays before being tested in patients with cancer. While some of these delays have a scientific basis, others do not. We need to do better. Innovative strategies need to move into early stage clinical trials as quickly as it is safe, and if successful, these therapies should efficiently obtain regulatory approval and widespread clinical application. In late 2009 and 2010 the Society for Immunotherapy of Cancer (SITC), convened an "Immunotherapy Summit" with representatives from immunotherapy organizations representing Europe, Japan, China and North America to discuss collaborations to improve development and delivery of cancer immunotherapy. One of the concepts raised by SITC and defined as critical by all parties was the need to identify hurdles that impede effective translation of cancer immunotherapy. With consensus on these hurdles, international working groups could be developed to make recommendations vetted by the participating organizations. These recommendations could then be considered by regulatory bodies, governmental and private funding agencies, pharmaceutical companies and academic institutions to facilitate changes necessary to accelerate clinical translation of novel immune-based cancer therapies. The critical hurdles identified by representatives of the collaborating organizations, now organized as the World Immunotherapy Council, are presented and discussed in this report. Some of the identified hurdles impede all investigators, others hinder investigators only in certain regions or institutions or are more relevant to specific types of immunotherapy or first-in-humans studies. Each of these hurdles can significantly delay clinical translation of promising advances in immunotherapy yet be overcome to improve outcomes of patients with cancer
Defining the critical hurdles in cancer immunotherapy
Scientific discoveries that provide strong evidence of antitumor effects in preclinical models often encounter significant delays before being tested in patients with cancer. While some of these delays have a scientific basis, others do not. We need to do better. Innovative strategies need to move into early stage clinical trials as quickly as it is safe, and if successful, these therapies should efficiently obtain regulatory approval and widespread clinical application. In late 2009 and 2010 the Society for Immunotherapy of Cancer (SITC), convened an "Immunotherapy Summit" with representatives from immunotherapy organizations representing Europe, Japan, China and North America to discuss collaborations to improve development and delivery of cancer immunotherapy. One of the concepts raised by SITC and defined as critical by all parties was the need to identify hurdles that impede effective translation of cancer immunotherapy. With consensus on these hurdles, international working groups could be developed to make recommendations vetted by the participating organizations. These recommendations could then be considered by regulatory bodies, governmental and private funding agencies, pharmaceutical companies and academic institutions to facilitate changes necessary to accelerate clinical translation of novel immune-based cancer therapies. The critical hurdles identified by representatives of the collaborating organizations, now organized as the World Immunotherapy Council, are presented and discussed in this report. Some of the identified hurdles impede all investigators; others hinder investigators only in certain regions or institutions or are more relevant to specific types of immunotherapy or first-in-humans studies. Each of these hurdles can significantly delay clinical translation of promising advances in immunotherapy yet if overcome, have the potential to improve outcomes of patients with cancer
DNA damage by lipid peroxidation products: implications in cancer, inflammation and autoimmunity
Oxidative stress and lipid peroxidation (LPO) induced by inflammation, excess metal storage and excess caloric intake cause generalized DNA damage, producing genotoxic and mutagenic effects. The consequent deregulation of cell homeostasis is implicated in the pathogenesis of a number of malignancies and degenerative diseases. Reactive aldehydes produced by LPO, such as malondialdehyde, acrolein, crotonaldehyde and 4-hydroxy-2-nonenal, react with DNA bases, generating promutagenic exocyclic DNA adducts, which likely contribute to the mutagenic and carcinogenic effects associated with oxidative stress-induced LPO. However, reactive aldehydes, when added to tumor cells, can exert an anticancerous effect. They act, analogously to other chemotherapeutic drugs, by forming DNA adducts and, in this way, they drive the tumor cells toward apoptosis. The aldehyde-DNA adducts, which can be observed during inflammation, play an important role by inducing epigenetic changes which, in turn, can modulate the inflammatory process. The pathogenic role of the adducts formed by the products of LPO with biological macromolecules in the breaking of immunological tolerance to self antigens and in the development of autoimmunity has been supported by a wealth of evidence. The instrumental role of the adducts of reactive LPO products with self protein antigens in the sensitization of autoreactive cells to the respective unmodified proteins and in the intermolecular spreading of the autoimmune responses to aldehyde-modified and native DNA is well documented. In contrast, further investigation is required in order to establish whether the formation of adducts of LPO products with DNA might incite substantial immune responsivity and might be instrumental for the spreading of the immunological responses from aldehyde-modified DNA to native DNA and similarly modified, unmodified and/or structurally analogous self protein antigens, thus leading to autoimmunity
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