10,453 research outputs found
Receptor tyrosine kinase and p16/CDKN2 expression in a case of tripe palms associated with non-small-cell lung cancer
Background: Tripe palms is a descriptive term for a cutaneous paraneoplastic keratoderma. Tripe palms are frequently associated with gastric and pulmonary carcinoma. The pathogenetic mechanism remains unknown. Objective: To determine the influence of receptor tyrosine kinases, which are both expressed in pulmonary carcinomas and in human skin, we performed expression studies on epidermal growth factor receptor (EGFR), HER2, HERS in a skin sample of tripe palms obtained from a patient with non-small-cell lung cancer with lymph node involvement. Two months after diagnosis, the patient had developed palmoplantar `tripe palms'. Additionally, the expression of SRC, c-myc and p16/CDKN2 were studied. Method: Conventional reverse-transcription polymerase chain reaction was performed on a tissue sample of tripe palms. Results: Weak expression of HER2 and of p16/CDKN2 was found. EGFR, HERS, c-myc and SRC were not expressed. Conclusion: Receptor tyrosine kinases of subclass I, the tyrosine kinase SRC and the oncogene c-myc play no major role in the pathogenesis of this case of tripe palms. Copyright (C) 2000 S. Karger AG. Basel
Kappa symmetry, generalized calibrations and spinorial geometry
We extend the spinorial geometry techniques developed for the solution of
supergravity Killing spinor equations to the kappa symmetry condition for
supersymmetric brane probe configurations in any supergravity background. In
particular, we construct the linear systems associated with the kappa symmetry
projector of M- and type II branes acting on any Killing spinor. As an example,
we show that static supersymmetric M2-brane configurations which admit a
Killing spinor representing the SU(5) orbit of are generalized
almost hermitian calibrations and the embedding map is pseudo-holomorphic. We
also present a bound for the Euclidean action of M- and type II branes embedded
in a supersymmetric background with non-vanishing fluxes. This leads to an
extension of the definition of generalized calibrations which allows for the
presence of non-trivial Born-Infeld type of fields in the brane actions.Comment: 9 pages, latex, references added and minor change
Cooperativity Beyond Caging: Generalized Mode Coupling Theory
The validity of mode coupling theory (MCT) is restricted by an uncontrolled
factorization approximation of density correlations. The factorization can be
delayed and ultimately avoided, however, by explicitly including higher order
correlations. We explore this approach within a microscopically motivated
schematic model. Analytic tractability allows us to discuss in great detail the
impact of factorization at arbitrary order, including the limit of avoided
factorization. Our results indicate a coherent picture for the capabilities as
well as limitations of MCT. Moreover, including higher order correlations
systematically defers the transition and ultimately restores ergodicity.
Power-law divergence of the relaxation time is then replaced by continuous but
exponential growth.Comment: 4 pages, 2 figure
A Unified Picture of the FIP and Inverse FIP Effects
We discuss models for coronal abundance anomalies observed in the coronae of
the sun and other late-type stars following a scenario first introduced by
Schwadron, Fisk & Zurbuchen of the interaction of waves at loop footpoints with
the partially neutral gas. Instead of considering wave heating of ions in this
location, we explore the effects on the upper chromospheric plasma of the wave
ponderomotive forces. These can arise as upward propagating waves from the
chromosphere transmit or reflect upon reaching the chromosphere-corona
boundary, and are in large part determined by the properties of the coronal
loop above. Our scenario has the advantage that for realistic wave energy
densities, both positive and negative changes in the abundance of ionized
species compared to neutrals can result, allowing both FIP and Inverse FIP
effects to come out of the model. We discuss how variations in model parameters
can account for essentially all of the abundance anomalies observed in solar
spectra. Expected variations with stellar spectral type are also qualitatively
consistent with observations of the FIP effect in stellar coronae.Comment: 25 pages, 4 figures, submitted to Ap
Thermalization of quantum systems by finite baths
We consider a discrete quantum system coupled to a finite bath, which may
consist of only one particle, in contrast to the standard baths which usually
consist of continua of oscillators, spins, etc. We find that such finite baths
may nevertheless equilibrate the system though not necessarily in the way
predicted by standard open system techniques. This behavior results regardless
of the initial state being correlated or not.Comment: 7 pages, 6 figures, accepted for publication in Eur. Phys. Let
Parathyroid localization
Twenty-nine consecutive patients with suspected primary hyperparathyroidism were examined preoperatively using ultrasound, sonographically guided fine needle aspiration, and aspirate immunostaining for PTH. In 25 patients, localization of enlarged parathyroid glands was successful. In 2 patients, the tumors were located retrosternally and, thus, could not be detected by ultrasound. One patient had a multinodular goiter which impeded localization. In 1 patient with renal osteodystrophy, 2 enlarged parathyroid glands in the neck were not visualized preoperatively. Cytology was not diagnostic, although some cytological features were suggestive of parathyroid cells. Immunostaining of the aspirated smears for PTH, however, correctly diagnosed all preoperatively localized lesions. Ultrasound should be the routine procedure of choice for preoperative localization of abnormal parathyroid glands in primary hyperparathyroidism. Fine needle aspiration and immunocytochemistry can supply confirmation, if necessary
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