1,040 research outputs found
The scalar glueball spectrum
We discuss scenarios for scalar glueballs using arguments based on sum rules,
spectral decomposition, the approximation, the scales of the
strong interaction and the topology of the flux tubes. We analyze the
phenomenological support of those scenarios and their observational
implications. Our investigations hint a rich low lying glueball spectrum.Comment: 11 pages: New title, figure, table and a more detailed comparison
with experiment
SAHA/TRAIL combination induces detachment and anoikis of MDA-MB231 and MCF-7 breast cancer cells
SAHA, an inhibitor of histone deacetylase activity, has been shown to sensitize tumor cells to apoptosis
induced by TRAIL, a member of TNF-family. In this paper we investigated the effect of SAHA/TRAIL
combination in two breast cancer cell lines, the ERa positive MCF-7 and the ERa negative MDA-MB231.
Treatment of MDA-MB231 and MCF-7 cells with SAHA in combination with TRAIL caused detachment of
cells followed by anoikis, a form of apoptosis which occurs after cell detachment, while treatment with
SAHA or TRAIL alone did not produce these effects. The effects were more evident in MDA-MB231 cells,
which were chosen for ascertaining the mechanism of SAHA/TRAIL action. Our results show that SAHA
decreased the level of c-FLIP, thus favouring the interaction of TRAIL with the specific death receptors
DR4 and DR5 and the consequent activation of caspase-8. These effects increased when the cells were
treated with SAHA/TRAIL combination. Because z-IEDT-fmk, an inhibitor of caspase-8, prevented both
the cleavage of the focal adhesion-kinase FAK and cell detachment, we suggest that activation of caspase-
8 can be responsible for both the decrement of FAK and the consequent cell detachment. In addition,
treatment with SAHA/TRAIL combination caused dissipation of DJm, activation of caspase-3 and
decrement of both phospho-EGFR and phospho-ERK1/2, a kinase which is involved in the phosphorylation
of BimEL. Therefore, co-treatment also induced decrement of phospho-BimEL and a concomitant
increase in the dephosphorylated form of BimEL, which plays an important role in the induction of
anoikis.
Our findings suggest the potential application of SAHA in combination with TRAIL in clinical trials for
breast cancer
Echinococcal Disease of the Liver in Pregnancy
Although echinococcal disease of the liver is common in some parts of the world, it is rarely seen in the
United States. Even from endemic areas, few reports deal with its treatment during pregnancy. A 25 year old
18 week pregnant Italian woman presented with pruritis and right upper quadrant pain. Ultrasound
revealed a cystic lesion in the left lobe of the liver. The cyst was treated by operative insertion of hypertonic
saline and capsulorrhaphy. The patient and her fetus had no postoperative complications. We believe that
the pregnant patient with symptomatic hepatic echinococcal disease should be treated operatively and that
insertion of hypertonic saline and capsulorrhaphy is the safest and most effective technique for both the
mother and fetus
Relativity and constituent quark structure in model calculations of parton distributions
According to recent studies, Parton Distribution Functions (PDFs) and Generalized Parton Distributions (GPDs) can be evaluated in a Constituent Quark Model (CQM) scenario, considering the constituent quarks as composite objects. In here, a fully covariant model for a system of two particles, together with its non relativistic limit, are used to calculate PDFs and GPDs. The analysis permits to realize that by no means the effects of Relativity can be simulated taking into account the structure of the constituent particles, the two effects being independent and necessary for a proper description of available high energy data in terms of CQM
VUV and X-ray coherent light with tunable polarization from single-pass free-electron lasers
Tunable polarization over a wide spectral range is a required feature of
light sources employed to investigate the properties of local symmetry in both
condensed and low-density matter. Among new-generation sources, free-electron
lasers possess a unique combination of very attractive features, as they allow
to generate powerful and coherent ultra-short optical pulses in the VUV and
X-ray spectral range. However, the question remains open about the possibility
to freely vary the light polarization of a free-electron laser, when the latter
is operated in the so-called nonlinear harmonic-generation regime. In such
configuration, one collects the harmonics of the free-electron laser
fundamental emission, gaining access to the shortest possible wavelengths the
device can generate. In this letter we provide the first experimental
characterization of the polarization of the harmonic light produced by a
free-electron laser and we demonstrate a method to obtain tunable polarization
in the VUV and X-ray spectral range. Experimental results are successfully
compared to those obtained using a theoretical model based on the paraxial
solution of Maxwell's equations. Our findings can be expected to have a deep
impact on the design and realization of experiments requiring full control of
light polarization to explore the symmetry properties of matter samples
Induction of apoptosis in human retinoblastoma cells by topoisomerase inhibitors
PURPOSE:To examine the apoptotic effect induced in human retinoblastoma Y79 cells by camptothecin, etoposide, and amsacrine, to examine the effect of these drugs on the expression of many apoptosis-related modulators, and to test the antiapoptotic effect exerted by insulin-like growth factor-I (IGF-I).
METHODS:Morphologic features of apoptosis were demonstrated using acridine orange- ethidium bromide staining and electron microscopy. DNA fragmentation was determined by means of an in situ cell detection procedure (TdT-dUTP terminal nick-end labeling [TUNEL]) or by electrophoresis on agarose gels and was quantified by enzyme-linked immunosorbent assay. The expression of apoptosis-related modulators was studied by western blot analysis. The processing of latent p53 was examined by means of pulse- chase analysis.
RESULTS:Camptothecin, etoposide, and amsacrine induced apoptosis in Y79 cells in a dose-dependent manner; camptothecin was the most efficacious compound. The effect, which was dependent on macromolecular synthesis, appeared after a lag of 8 hours and increased for as long as 24 hours. It was lower in cells treated with IGF-I, a potent mitogenic factor. Camptothecin and etoposide increased the p53 level after 4 hours of treatment, before the onset of apoptosis. This effect seemed to be a consequence of the conversion of latent p53 to one that is transcriptionally active. The drugs also induced an increase in p53-related proteins, such as p21, Bax, and IGF binding protein-3 (IGF-BP3), and caused a significant reduction of the Bcl-2 level. The latter effect was less evident in cells pretreated with IGF-I.
CONCLUSIONS:Topoisomerase inhibitors induce apoptosis in Y79 cells. This event is accompanied by a decrease in the expression of Bcl-2, a death antagonist, and an increase in that of Bax, a death agonist. A probable consequence of these modifications is the activation of ICE-like activity with degradation of poly-(adenosine diphosphate [ADP] ribose)-polymerase. Insulin-like growth factor-I exerts an antiapoptotic action in Y79 cells, and this function is most likely reduced by the overexpression of IGF-BP3 that is induced by drug treatment
Pseudoscalar glueball and mixing
We have performed a dynamical analysis of the mixing in the pseudoscalar
channel with the goal of understanding the existence and behavior of the
pseudoscalar glueball. Our philosophy has not been to predict precise values of
the glueball mass but to exploit an adequate effective theory to the point of
breaking and to analyze which kind of mechanisms restore compatibility with
data. Our study has lead to analytical solutions which allow a clear
understanding of the phenomena. The outcome of our calculation leads to a large
mass glueball MeV, to a large glue content of the
and to mixing angles in agreement with previous numerical studies.Comment: 12 pages, 8 figure
A short story of 3AB-OS cancer stem cells, a possible model for studying cancer stemness
Cancer Stem Cells (CSCs) are thought to be the cause of cancer initiation, growth and development. Thus, a
challenge in cancer research is their identification and eradication. In our laboratory, by chemical treatment of the
human osteosarcoma (OS) MG63 cell line, we have isolated and characterized 3AB-OS cells, a human OS CSC line.
3AB-OS cells transdifferentiate in vitro into cells of the three derivatives germ layers and, when xenografted in athymic
mice they are highly tumorigenic and recapitulate in vivo crucial features of human OS. They even express a
reprogrammed energy metabolism, with a dependence on glycolytic metabolism more strong than parental MG63
cells. 3AB-OS cells have chromosomes showing a great number of abnormalities which are very similar to
abnormalities found in both pediatric and adult osteosarcomas. In comparison with parental MG63 cells (where TP53
gene is hypermethylated, rearranged and in single copy), 3AB-OS cells have TP53 gene unmethylated, rearranged and
in multiple copies. Moreover, the mutp53 (p53-R248W/P72R) is post-translationally stabilized, has nuclear localization
and a gain of function. A great number of results obtained in our laboratories suggested that p53 mutation could be the
“driver mutation” at the origin of the transformation of MG63 cells into 3AB-OS CSCs
Parthenolide induces caspase-independent cell death in osteosarcoma, melanoma and breast cancer cells through the induction of oxidative stress.
Parthenolide, a sesquiterpene lactone found in European feverfew, is used in
traditional medicine for its anti-inflammatory activity. In addition, parthenolide has
been considered as a novel and effective anti-tumor agent because it induces cytotoxic effects in several tumor cell lines.
Our studies demonstrated that parthenolide exerted strong cytotoxic effects in osteosarcoma MG63 and melanoma SK-Mel28 cells in culture. Staining with Hoechst 33342 revealed in most cells after brief periods of treatments (3-5h) chromatin
condensation and fragmentation, while only few cells were PI-positive. Prolonging the treatment (5-14h) PI-positive cells strongly augmented, denouncing the increase of necrotic effects. All these effects were prevented by NAC, while caspase inhibitors were ineffective, thus suggesting a caspase-independent cell death. The study of the mechanism of action provided evidence that treatment with parthenolide rapidly
stimulated (1-2 h) ROS generation, in particular by inducing activation of extracellular signal-regulated kinase1/2 and NADPH oxidase. This event caused depletion of thiol groups and glutathione, NF-\u3baB inhibition, JNK activation and cell detachment
from the matrix. ROS generation together with mitochondrial accumulation of Ca2+
favoured dissipation of \u394\u3c8m, which appeared primarily determined by the opening of the permeability transition pore (PTP), since \u394\u3c8m loss was partially prevented by cyclosporin A, an inhibitor of PTP opening.
Recently, we focused our attention on MDA-MB231 cells, a very aggressive and poorly differentiated breast cancer cell line, which is negative for estrogen receptor alpha.
Preliminary results suggested that parthenolide induced cell death in these cells with a mechanism similar to that demonstrated in osteosarcoma and melanoma cells.
Interestingly, we demonstrated that in MDA-MB231 cells the effect of parthenolide was potentiated by the addition of z-VAD-fmk, a general inhibitor of caspases. Studies are in progress to elucidate the mechanism of this interaction which could suggest new strategies for the treatment of ER-\u3b1 negative breast cancer
Hadron Correlators and the Structure of the Quark Propagator
The structure of the quark propagator of in a confining background is
not known. We make an Ansatz for it, as hinted by a particular mechanism for
confinement, and analyze its implications in the meson and baryon correlators.
We connect the various terms in the K\"allen-Lehmann representation of the
quark propagator with appropriate combinations of hadron correlators, which may
ultimately be calculated in lattice . Furthermore, using the positivity of
the path integral measure for vector like theories, we reanalyze some mass
inequalities in our formalism. A curiosity of the analysis is that, the exotic
components of the propagator (axial and tensor), produce terms in the hadron
correlators which, if not vanishing in the gauge field integration, lead to
violations of fundamental symmetries. The non observation of these violations
implies restrictions in the space-time structure of the contributing gauge
field configurations. In this way, lattice can help us analyze the
microscopic structure of the mechanisms for confinement.Comment: 12 pp in LaTeX, preprint Univ. of Valencia, FTUV/94-16, IFIC/94-15.
To appear in Z.Phys.
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