julilili42/papers huggingface dataset:
Pair condensation and bound states in fermionic systems
2006-03-16

We study the finite temperature-density phase diagram of an attractive fermionic system that supports two-body (dimer) and three-body (trimer) bound states in free space. Using interactions characteristic for nuclear systems, we obtain the critical temperature T_c2 for the superfluid phase transition and the limiting temperature T_c3 for the extinction of trimers. The phase diagram features a Cooper-pair condensate in the high-density, low-temperature domain which, with decreasing density, crosses over to a Bose condensate of strongly bound dimers. The high-temperature, low-density domain is populated by trimers whose binding energy decreases toward the density-temperature domain occupied by the superfluid and vanishes at a critical temperature T_c3 > T_c2.
Proteasomes shape the repertoire of T cells participating in antigen-specific immune responses
2006-03-20

Differences in the cleavage specificities of constitutive proteasomes and immunoproteasomes significantly affect the generation of MHC class I ligands and therefore the activation of CD8-positive T cells. Based on these findings, we investigated whether proteasomal specificity also influences CD8-positive T cells during thymic selection by peptides derived from self proteins. We find that one of the self peptides responsible for positive selection of ovalbumin-specific OT-1 T cells, which is derived from the f-actin capping protein (Cpα1), is efficiently generated only by immunoproteasomes. Furthermore, OT-1 mice backcrossed onto low molecular mass protein 7 (LMP7)-deficient mice show a 50% reduction of OT-1 cells. This deficiency is also observed after transfer of BM from OT-1 mice in LMP7-deficient mice and can be corrected by the injection of the Cpα1 peptide. Interestingly, WT and LMP7-deficient mice mount comparable immune responses to the ovalbumin-derived epitope SIINFEKL. However, their cytotoxic T lymphocytes (CTL) differ in the use of T cell receptor Vβ genes. CTL derived from WT mice use Vβ8 or Vβ5 (the latter is also used by OT-1 cells), whereas SIINFEKL-specific CTL from LMP7-deficient mice are exclusively Vβ8-positive. Taken together, our experiments provide strong evidence that proteasomal specificity shapes the repertoire of T cells participating in antigen-specific immune responses.
The Focal Plane Instrumentation of the ROSITA Telescope
2006-03-21

The X-ray astronomy satellite ROSITA is planned to perform an X-ray all sky survey in the medium energy range up to 10 keV with an imaging telescope. During the mission the whole sky will be scanned and selected areas will be observed with longer exposures. Especially cosmic X-ray sources obscured by large amounts of gas and dust like accreting black holes and active galactic nuclei as well as the hot gas of distant clusters of galaxies can be seen in this energy band. The ROSITA payload consists of an imaging X-ray telescope made of seven separate mirror modules with different viewing directions. Each module has a 27 fold nested Wolter type I mirror system. The seven mirror systems share a common X-ray camera in the focal plane with seven single frame store pnCCD detectors, each dedicated to one mirror module. The frame store pnCCD is a further development of the pnCCD detector of the EPIC camera aboard the XMM-Newton satellite. Due to the high readout frequency of the CCDs (20 s/sup -1/) the angular resolution of the telescope is not degraded despite the scanning motion of the satellite. The CCDs are operated at a temperature of -80/spl deg/C. Cooling is provided by passive radiators and thermoelectric coolers. To reduce the fluorescent X-ray background, generated by cosmic radiation in the materials of the detector housing, the CCDs are surrounded by a graded shielding. The detector performance will be checked in orbit with calibration sources. We will give an overview of the mechanical, thermal and electrical concept of the focal plane camera system.
Tissue-Specific Effects of In Vitro Fertilization Procedures on Genomic Cytosine Methylation Levels in Overgrown and Normal Sized Bovine Fetuses1
2006-03-22

Epigenetic perturbations are assumed to be responsible for phenotypic abnormalities of fetuses and offspring originating from in vitro embryo techniques. We studied 29 viable Day-80 bovine fetuses to assess the effects of two in vitro fertilization protocols (IVF1 and IVF2) on fetal phenotype and genomic cytosine methylation levels in liver, skeletal muscle, and brain. The IVF1 protocol employed 0.01 U/ml of FSH and LH in oocyte maturation medium and 5% estrous cow serum (ECS) in embryo culture medium, whereas the IVF2 protocol employed 0.2 U/ml of FSH and no LH for oocyte maturation and 10% ECS for embryo culture. Comparisons with in vivo-fertilized controls (n=14) indicated an apparently normal phenotype for IVF1 fetuses (n=5), but IVF2 fetuses (n=10) were significantly heavier (19.9%) and longer (4.7%), with increased heart (25.2%) and liver (27.9%) weights, and thus displayed an overgrowth phenotype. A clinicochemical screen of 18 plasma parameters revealed significantly increased levels of insulin-like growth factor 1 (40.8%) and creatinine (37.5%) in IVF2, but not in IVF1, fetuses. Quantification of genomic 5-methylcytosine (5mC) by capillary electrophoresis indicated that both IVF1 and IVF2 fetuses differed from controls. We observed significant DNA hypomethylation in liver and muscle of IVF1 fetuses (-16.1% and -9.3%, respectively) and significant hypermethylation in liver of IVF2 fetuses (+11.2%). The 5mC level of cerebral DNA was not affected by IVF protocol. Our data indicate that bovine IVF procedures can affect fetal genomic 5mC levels in a protocol- and tissue-specific manner and show that hepatic hypermethylation is associated with fetal overgrowth and its correlated endocrine changes.
The Kinesin KIF1C and Microtubule Plus Ends Regulate Podosome Dynamics in Macrophages
2006-03-23

Microtubules are important for the turnover of podosomes, dynamic, actin-rich adhesions implicated in migration and invasion of monocytic cells. The molecular basis for this functional dependency, however, remained unclear. Here, we show that contact by microtubule plus ends critically influences the cellular fate of podosomes in primary human macrophages. In particular, we identify the kinesin KIF1C, a member of the Kinesin-3 family, as a plus-end–enriched motor that targets regions of podosome turnover. Expression of mutation constructs or small interfering RNA-/short hairpin RNA-based depletion of KIF1C resulted in decreased podosome dynamics and ultimately in podosome deficiency. Importantly, protein interaction studies showed that KIF1C binds to nonmuscle myosin IIA via its PTPD-binding domain, thus providing an interface between the actin and tubulin cytoskeletons, which may facilitate the subcellular targeting of podosomes by microtubules. This is the first report to implicate a kinesin in podosome regulation and also the first to describe a function for KIF1C in human cells.
Atom interferometer based on phase coherent splitting of Bose-Einstein condensates with an integrated magnetic grating
2006-03-23

We report the phase coherent splitting of Bose-Einstein condensates by means of a phase grating produced near the surface of a micro-electronic chip. A lattice potential with a period of m is generated by the superposition of static and oscillating magnetic fields. Precise control of the diffraction is achieved by controlling the currents in the integrated conductors. The interference of overlapping diffraction orders is observed after 8ms of propagation in a harmonic trap and subsequent ballistic expansion of the atomic ensemble. By analyzing the interference pattern we show a reproducible phase relation between the diffraction orders with an uncertainty given by the resolution of the diffraction grating.
Basal cell carcinoma: histological classification and body-site distribution
2006-03-24

Background Basal cell carcinoma (BCC) is the most common cancer worldwide in white‐skinned populations. Recent studies suggest that BCC is not a single entity and that different histological subtypes show different clinical behaviour and might have different aetiology. Objectives To provide information on the incidence of BCC by histopathological subtype and body site. Methods A case series of BCC from a prospective population‐based register study collecting information on all excised and histologically confirmed skin cancers in Townsville, north Australia between 1997 and 1999. Results Age‐standardized incidence rates for nodular BCC were 727·1 per 100 000 inhabitants per year for males and 411·8 for females, while rates for superficial BCC were 336·5 for males and 251·4 for females. Incidence rates for 'high risk' BCC were 261·3 for males, 146·5 for females with infiltrative, and 156·7 for males and 100·2 for females with micronodular types. Superficial BCC occurred at a younger age, particularly in female patients. For all histological subtypes and both genders relative tumour density was highest for the face, followed by the neck. An exception was superficial BCC in males, where the posterior trunk was second, followed by the neck. Conclusions The study found a higher rate of superficial BCC than previous studies from less sun‐exposed countries, and a more equal distribution of superficial BCC on face, trunk and limbs. These results seem to blur the difference between intermittent and continuous sun exposure as the causative environmental agents. The clinical implications of 'high risk' BCC rates are discussed.
On spontaneous wave function collapse and quantum field theory
2006-03-24

One way of obtaining a version of quantum mechanics without observers, and thus of solving the paradoxes of quantum mechanics, is to modify the Schrödinger evolution by implementing spontaneous collapses of the wave function. An explicit model of this kind was proposed in 1986 by Ghirardi, Rimini &amp; Weber (GRW), involving a nonlinear, stochastic evolution of the wave function. We point out how, by focusing on the essential mathematical structure of the GRW model and a clear ontology, it can be generalized to (regularized) quantum field theories in a simple and natural way.
Standardized data collection for multi-center clinical studies of severe malaria in African children: establishing the SMAC network
2006-03-24

The Severe Malaria in African Children (SMAC) network was established to conduct mortality-based trials. Although falciparum malaria kills more than one million children each year, single centers cannot enroll enough patients to detect reductions of 20-30% in mortality rates. Our aim was to quantify and describe severe malaria across a variety of epidemiological settings so that we could design intervention studies with more precise sample size estimates. We used a standardized surveillance mechanism to capture clinical, laboratory and outcome data on all parasitemic children admitted to hospital. Between December 2000 and December 2003, 20333 patients were enrolled at five sites. The frequency of severe malaria syndromes (cerebral malaria, severe malarial anemia and acidosis) differed between sites, as did the syndrome-specific mortality rates. Intervention studies targeted at reducing mortality in one or a combination of severe malaria syndromes would require 3-4 years to complete within the existing network. These data provide more accurate estimates of the disease burden of children hospitalized for malaria in sub-Saharan Africa. Networks are required to recruit enough patients for mortality-based studies and to encompass the epidemiological diversity of malaria in sub-Saharan Africa. SMAC represents the first effort to develop this capacity.
Alteration of subcellular and cellular expression patterns of cyclin B1 in renal cell carcinoma is significantly related to clinical progression and survival of patients
2006-03-24

Abstract Cyclin B1, identified as a regulator of late cell cycle, is involved in the development and progression of a variety of human malignancies. To clarify the role of cyclin B1 in the pathogenesis and prognosis of renal cell carcinoma (RCC), protein expression was compared with clinicopathological characteristics of patients as well as the long‐term survival after surgical therapy. Expression analysis was carried out by immunohistochemistry and tissue microarray analysis. The microarrays that represented the primary tumors, their invasion front and normal peritumoral renal parenchyma contained 753 tissue cores obtained from 251 randomly selected nephrectomy specimens. Immunopositivity within the primary tumors was significantly associated with tumor stage (pT) ( p &lt; 0.01), lymph node status (pN) ( p &lt; 0.01) as well as the presence of systemic metastatic disease ( p = 0.01). Subcellular expression in the cytoplasm of tumor cells significantly correlated with pT ( p = 0.02) and pN ( p = 0.03). When peritumoral tissue samples exhibited a relative amount of &lt;10% of positively reacting epithelial cells, cyclin B positivity was identified to predict long‐term survival of patients in univariate analysis ( p &lt; 0.01) whereas borderline significance was observed in multivariate statistical analysis ( p = 0.05). Increased intratumoral cyclin B1 positivity and aberrant localization of signals within the cytoplasm of tumor cells is positively correlated with the tendency towards tumor progression, indicating the significant role of cyclin B1 in the development and pathogenesis of RCC. The result of uni‐ and multivariate statistical analysis suggests the prognostic value of cyclin B1 for RCC patients. © 2006 Wiley‐Liss, Inc.
Thymus and myasthenia gravis: antigen processing in the human thymus and the consequences for the generation of autoreactive T cells
2006-03-24

Peptides displayed by antigen presenting cells in the thymus shape the T cell repertoire. We investigated the antigen processing machinery of the MHC class II presentation pathway and describe the differential expression of lysosomal proteases in compartments of the thymus and the peripheral lymphoid tissue. Overexpression of certain proteases found in the thymus and thymoma associated with myasthenia gravis is likely to affect tolerance induction and may promote the generation autoreactive CD4(+) T helper cells.
Muscarinic acetylcholine receptors as effector sites for present and future therapeutic applications: focus on non-neural cholinergic systems
2006-03-24

This review summarises the expression and function of muscarinic acetylcholine receptors (mAChR) in the organism, and the therapeutic implications of recent patents on cholinergic agents. Aside from the well known therapeutic applications of parasympathomimetic and -lytic drugs for diseases of the heart, eye, circulation and airways, new possible fields for mAChR agonists and antagonists in clinical therapy have begun to emerge. In particular, the role of non-neural cholinergic mechanisms in tissue regeneration, development and even carcinogenesis has become increasingly studied by a number of research teams within the last decade. This review exemplifies and contrasts experimental findings of mAChR drug action, and discusses these with regard to patents from the past 4 years.
Disulfide-coupled folding of the circulating form of uroguanylin
2006-03-24

Plasma form of human uroguanylin (guanylyl cyclase activating peptide, GCAP-II) is an endogenous ligand for a particulate guanylyl cyclase C [1]. The peptide consists of 24 amino acid residues and two disulfide linkages [1], as shown in Figure 1. Our findings indicate that a linear peptide, containing 4 cysteine residues, is thermodynamically impossible to produce a peptide with the native disulfide bond pairing as a major product by air-oxidation in vitro, and that the correct disulfide bond pairing is required for its biological activity. This finding prompted us to examine how the peptide is able to overcome this energic barrier to folding. This report describes a study of the disulfide-coupled foldings of GCAP-II and the precursor protein (proGCAP-II), in order to elucidate the folding mechanism.
Humor and smiling
2006-03-27

These results confirm the clinically derived hypothesis of separate cortical regions responsible for the production of emotionally driven vs voluntary facial expressions. The right orbitofrontal decrease reconciles inconsistencies between clinical and functional imaging findings and may reflect a disinhibition of facial emotional expression.
Peri-prosthetic bone density after implantation of a custom-made femoral component
2006-03-27

Peri-prosthetic bone loss caused by stress shielding may be associated with aseptic loosening of femoral components. In order to increase primary stability and to reduce stress shielding, a three-dimensional, cementless individual femoral (Evolution K) component was manufactured using pre-operative CT scans. Using dual energy x-ray absorptiometry, peri-prosthetic bone density was measured in 43 patients, three months, six months, 3.6 and 4.6 years after surgery. At final follow-up there was a significant reduction in mean bone density in the proximal Gruen zones of −30.3% (zone 7) and −22.8% (zone 1). The density in the other zones declined by a mean of between −4% and −16%. We conclude that the manufacture of a three-dimensional, custom-made femoral component could not prevent a reduction in peri-prosthetic bone density.
Intramyocellular lipid quantification from 1H long echo time spectra at 1.5 and 3 T by means of the LCModel technique
2006-03-27

Abstract Purpose To introduce a method of independent determination of CH 2 and CH 3 components of intramyocellular lipids (IMCLs) by using long TE for spectra measurement and LCModel for spectra evaluation, to test this technique in controls and insulin‐resistant subjects, and to compare results at 1.5 and 3 T. Materials and Methods Eight healthy volunteers and 11 patients with type 2 diabetes mellitus underwent measurement using a 1.5‐T MR scanner; six healthy volunteers were measured using a 3‐T MR scanner. Spectra from the tibialis anterior muscle were acquired by using a point resolved spectroscopy (PRESS) sequence with the following parameters: TR/TE/ACQ = 2000 msec/270 msec/256. Spectra were processed by LCModel 6.1 software with two types of adopted basis‐set. Results Spectra with good separation of both CH 2 and CH 3 components of IMCL and extramyocellular lipids (EMCLs) were obtained and the LCModel routine was successfully applied. The reproducibility comparison ( N = 7 at 1.5 T vs. N = 5 at 3 T) showed that better results can be obtained at higher B 0 values. The comparison of the healthy and insulin‐resistant subjects proved that both IMCL_CH 2 /Cr and IMCL_CH 3 /Cr ratios significantly differ. Conclusion Long TE spectroscopy of the human muscle with IMCL quantification using the LCModel technique can detect changes in IMCL levels as well as help in the study of fatty acyl chain composition. Using a higher field strength increased the intra‐individual reproducibility by approximately 150% J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Synthesis of Pentasaccharide Fragments Related to the O‐Specific Polysaccharide of Shigella flexneri Serotype 1a
2006-03-27

Abstract The synthesis of the pentasaccharide 5‐aminopentylglycosides α‐ L ‐Rha p ‐(1→3)‐[α‐ D ‐Glc p ‐(1→4)]‐β‐ D ‐Glc p NAc‐(1→2)‐α‐ L ‐Rha p ‐(1→2)‐α‐ L ‐Rha p ‐1‐ O ‐(CH 2 ) 5 NH 2 ( 29 ) andα‐ L ‐Rha p ‐(1→3)‐α‐ L ‐Rha p ‐(1→3)‐[α‐ D ‐Glc p ‐(1→4)]‐β‐ D ‐Glc p NAc‐(1→2)‐α‐ L ‐Rha p ‐1‐ O ‐(CH 2 ) 5 NH 2 ( 28 ), related to the O ‐specific polysaccharide of Shigella flexneri serotype 1a by coupling of the suitably protected trisaccharides α‐ D ‐Glc p ‐(1→4)‐β‐ D ‐Glc p (1→2)‐α‐ L ‐Rha p ‐1‐ O ‐(CH 2 ) 5 NH 2 ( 23 ) and α‐ L ‐Rha p ‐(1→3)‐[α‐ D ‐Glc p ‐(1→4)]‐β‐ D ‐Glc p ‐1‐SPh ( 26 ) with the corresponding rhamnosyl glycosides α‐ L ‐Rha p ‐(1→3)‐α‐ L ‐Rha p ‐1‐SEt ( 17 ) and α‐ L ‐Rha p ‐(1→3)‐α‐ L ‐Rha p ‐1‐ O ‐(CH 2 ) 5 NH 2 ( 13 ), is described. Building blocks 23 and 26 were prepared by intramolecular glycosylation of an unsymmetrically tethered cellobiosamine derivative. (© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2006)
Roost Structure, Modification, and Availability in the White‐throated Round‐eared Bat,Lophostoma silvicolum(Phyllostomidae) Living in Active Termite Nests1
2006-03-28

ABSTRACT We studied roost structure, modification, and availability in Lophostoma silvicolum (Phyllostomidae), an insectivorous gleaning bat, on Barro Colorado Island (BCI), Panamá. Collection of nest material beneath termitaria and infrared video filming indicated that males of L. silvicolum excavate and maintain cavities inside active termite nests. A binary logistic regression analysis showed that to be suitable as roosts, termite nests have to be larger than 30 cm in diameter and taller than 30 cm, well shaded, with few transecting branches, and freely accessible from below. Use of active termite nests as roosts may provide several benefits to L. silvicolum , including reduction of competition for roost sites with sympatric bat species, reduced parasite load and a suitable microclimate. A comparison of number of all termite nests in selected forest plots with number of termite nests that are potentially suited as bat roosts and number of termite nests that are actually used by bats suggests that L. silvicolum may not be roost‐limited on BCI in spite of its highly specialized roost choice.
Antimalarial Activity of a Synthetic Endoperoxide (RBx-11160/OZ277) against Plasmodium falciparum Isolates from Gabon
2006-03-28

ABSTRACT OZ277 is a newly developed, fully synthetic endoperoxide antimalarial that we tested against field isolates from Gabon. A comparison of activities of OZ277 with artesunate, mefloquine, and chloroquine showed OZ277 to be highly active against all parasite isolates. Artesunate and mefloquine also showed potent antiparasitic activity, but all isolates were chloroquine resistant.
Post‐translational regulation of EAAT2 function by co‐expressed ubiquitin ligase Nedd4‐2 is impacted by SGK kinases
2006-03-29

Abstract The human excitatory amino acid transporter (EAAT)2 is the major glutamate carrier in the mammalian CNS. Defective expression of the transporter results in neuroexcitotoxicity that may contribute to neuronal disorders such as amyotrophic lateral sclerosis (ALS). The serum and glucocorticoid inducible kinase (SGK) 1 is expressed in the brain and is known to interact with the ubiquitin ligase Nedd4‐2 to modulate membrane transporters and ion channels. The present study aimed to investigate whether SGK isoforms and the related kinase, protein kinase B (PKB), regulate EAAT2. Expression studies in Xenopus oocytes demonstrated that glutamate‐induced inward current (I GLU ) was stimulated by co‐expression of SGK1, SGK2, SGK3 or PKB. I GLU is virtually abolished by Nedd4‐2, an effect abrogated by additional co‐expression of either kinase. The kinases diminish the effect through Nedd4‐2 phosphorylation without altering Nedd4‐2 protein abundance. SGKs increase the transporter maximal velocity without significantly affecting substrate affinity. Similar to glutamate‐induced currents, [ 3 H] glutamate uptake and cell surface abundance of the transporter were increased by the SGK isoforms and down‐regulated by the ubiquitin ligase Nedd4‐2. In conclusion, all three SGK isoforms and PKB increase EAAT2 activity and plasma membrane expression and thus, may participate in the regulation of neuroexcitability.