julilili42/papers huggingface dataset:
Evidence for the involvement of Plasmodium falciparum proteins in the formation of new permeability pathways in the erythrocyte membrane
2006-03-03

Summary The intraerythrocytic developmental stages of the malaria parasite Plasmodium falciparum are responsible for the clinical symptoms associated with malaria tropica. The non‐infected human erythrocyte is a terminally differentiated cell that is unable to synthesize proteins and lipids de novo , and it is incapable of importing a number of solutes that are essential for parasite proliferation. Approximately 12–15 h after invasion the parasitized cell undergoes a marked increase in its permeability to a variety of different solutes present in the extracellular milieu. The increase is due to the induction in the erythrocyte membrane of ‘new permeability pathways’ which have been characterized in some detail in terms of their transport and electrophysiological properties, but which are yet to be defined at a molecular level. Here we show that these pathways are resistant to trypsin but are abolished by treatment of intact infected erythrocytes with chymotrypsin. On resuspension of chymotrypsinized cells in chymotrypsin‐free medium the pathways progressively reappear, a process that can be inhibited by cytotoxic agents, and by brefeldin A which inhibits protein secretion. Our results provide evidence for the involvement of parasite encoded proteins in the generation of the pathways, either as components of the pathways themselves or as auxiliary factors.
Karst Spring Responses Examined by Process‐Based Modeling
2006-03-08

Abstract Ground water in karst terrains is highly vulnerable to contamination due to the rapid transport of contaminants through the highly conductive conduit system. For contamination risk assessment purposes, information about hydraulic and geometric characteristics of the conduits and their hydraulic interaction with the fissured porous rock is an important prerequisite. The relationship between aquifer characteristics and short‐term responses to recharge events of both spring discharge and physicochemical parameters of the discharged water was examined using a process‐based flow and transport model. In the respective software, a pipe‐network model, representing fast conduit flow, is coupled to MODFLOW, which simulates flow in the fissured porous rock. This hybrid flow model was extended to include modules simulating heat and reactive solute transport in conduits. The application of this modeling tool demonstrates that variations of physicochemical parameters, such as solute concentration and water temperature, depend to a large extent on the intensity and duration of recharge events and provide information about the structure and geometry of the conduit system as well as about the interaction between conduits and fissured porous rock. Moreover, the responses of solute concentration and temperature of spring discharge appear to reflect different processes, thus complementing each other in the aquifer characterization.
Ecto-5′-nucleotidase (cd73)-dependent and -independent generation of adenosine participates in the mediation of tubuloglomerular feedback in vivo
2006-03-08

Tubuloglomerular feedback (TGF) describes a sequence of events linking salt concentrations in tubular fluid at the macula densa to the vascular tone of the afferent arteriole and thus to the glomerular filtration rate (GFR) of the same nephron. The signal transduction pathways of TGF remain incompletely understood, but both ATP release from macula densa cells and local formation of adenosine were suggested to be involved in the process. To test the role of extracellular formation of adenosine by ecto-5′-nucleotidase (cd73) in TGF, in regulation of GFR, and in tubular reabsorption, renal clearance and micropunture experiments were performed in cd73 wild-type (cd73 +/+ ) and knockout mice (cd73 −/− ). The cd73 −/− mice presented normal mean arterial blood pressure, but modestly lower whole kidney and single nephron GFR (SNGFR). Fractional reabsorption of Na + and K + up to the late proximal tubule, distal tubule, as well as urine were not significantly different between cd73 −/− and cd73 +/+ mice. Lack of cd73 resulted in a diminished TGF response, as indicated by smaller changes of stop-flow pressure in response to increasing loop of Henle perfusion from 0 to 25 nl/min, smaller differences in SNGFR determined from paired proximal and distal tubular collections, and by smaller fractional changes of distal SNGFR in response to adding 6 nl/min of artificial tubular fluid to free-flowing proximal tubules. The TGF response in cd73 +/+ mice and the residual TGF response in cd73 −/− mice were completely inhibited by adenosine A 1 -receptor blockade. The results suggest that extracellular formation of adenosine by ecto-5′-nucleotidase (cd73) is dispensable for normal fluid, Na + , or K + reabsorption along the nephron, but contributes to the regulation of GFR. Adenosine generated by both ecto-5′-nucleotidase (cd73)-dependent and -independent mechanisms participates in the mediation of TGF in vivo.
Long-Term Malaria Prophylaxis for Travelers
2006-03-08

Long-term malaria prophylaxis is hampered by a lack of standardization and compliance. Advice should be individually optimized to achieve a high degree of protection and compliance. Individual risk assessment takes into consideration the duration of stay in the endemic area, the individual exposure, the seasonal transmission rates, and the drug-resistance situation. Methods for prevention of exposure may help reduce the reliance on chemoprophylactic drugs. Exposure-prevention methods may be combined with standby treatment in lower transmission areas if the traveler has been trained to take the antimalarials appropriately. Although suitable for long-term use, chloroquine and chloroquine-proguanil cannot be used as prophylaxis owing to high resistance rates in most endemic regions. Mefloquine is suitable for most malaria-endemic regions, although its use is restricted by neuropsychiatric side effects, particularly in women. Doxycycline is also appropriate; experience with long-term malaria prophylaxis is available for up to 6 months. The use ofatovaquone-proguanil is restricted to 28 days in some countries, but clinical studies indicate that its use is suitable for at least 20 weeks. Primaquine is also effective for chemoprophylaxis; experience is limited to 1 year of protection against falciparum and vivax malaria. When giving individual recommendations to a traveler, special considerations for backpackers, expatriates, and frequent travelers may apply.
Avoiding Misdiagnosis of Imported Malaria: Screening of Emergency Department Samples with Thrombocytopenia Detects Clinically Unsuspected Cases
2006-03-08

The problem of clinically unsuspected malaria seems to be more common than generally expected and is dependent on the local incidence of malaria as well as clinical and laboratory expertise. The blind screening of all thrombocytopenic samples with <100,000/microL may be a cost-effective way to reduce the misdiagnosis of imported malaria.
Cutaneous and Medullar Gnathostomiasis in Travelers to Mexico and Thailand
2006-03-08

Gnathostomiasis is a rare nematode disease acquired by travelers to endemic areas. The most common clinical presentations are cutaneous forms; however, neurologic involvement can also occur. We present two cases of gnathostomiasis, one of them with severe neurologic complications, in Spanish travelers to Thailand and Mexico, who consumed local food and became infected.
Shape coexistence effects in78Kr
2006-03-08

Results are presented on shape coexistence effects in the nucleus 78Kr obtained within the complex version of the EXCITED VAMPIR variational approach. Oblate–prolate coexistence and mixing is found to be responsible for the characteristic features identified at low excitation energy for low and intermediate as well as high spins. At the highest investigated spins, the high density of configurations having different deformations results in the fragmentation of B(E2) strengths explaining the experimentally identified forking of the spectrum. The present investigation indicates the essential role played by particular neutron–proton matrix elements of the effective interaction on the oblate–prolate coexistence and mixing in the 78Kr nucleus.
Stability of quasi-two-dimensional Bose-Einstein condensates with dominant dipole-dipole interactions
2006-03-09

We consider quasi-two-dimensional atomic/molecular Bose-Einstein condensates with both contact and dipole-dipole interactions. It is shown that, as a consequence of the dimensional reduction, and within mean-field theory, the condensates do not develop unstable excitation spectra, even when the dipole-dipole interaction completely dominates the contact interaction.
D-mesons and charmonium states in hot pion matter
2006-03-09

We calculate the in-medium meson self-energies in a hot pion gas induced by resonance interactions with pions. The appropriate resonances in the {\\it s},~ {\\it p} and {\\it d} waves of the meson-pion pair are represented by low lying scalar, vector and tensor mesons. At temperatures around 200 MeV the D-meson mass drops by and the scattering width grows up to . Similar medium effects are found for the vector mesons. This opens and/or enhances the decay and/or dissociation channels of the charmonium states , and to pairs in pion matter.
Calcium TetraborideDoes It Exist? Synthesis and Properties of a Carbon-Doped Calcium Tetraboride That Is Isotypic with the Known Rare Earth Tetraborides
2006-03-09

Crystalline samples of carbon-doped CaB4 were synthesized by solid-state reactions in sealed niobium ampules from the elements Ca, B, and C. The structure was determined by single-crystal X-ray diffraction (P4/mbm, Z = 4, a = 7.0989(7) A, c = 4.1353(5) A, R1 = 0.026, and wR2 = 0.058) revealing an atom arrangement containing a three-dimensional boron network built up from B6 octahedra and B2 dumbbells which is well-known from the structures of rare earth tetraborides. Crystals of CaB(4-x)Cx are black with a metallic luster and behave stable against mineral acids. Band structure calculations indicate that CaB4 is a stable semiconducting compound with a narrow band gap and that carbon should not necessarily be required for the stability of this compound. The presence of carbon in the crystalline samples of CaB(4-x)Cx was indicated by electron energy loss spectroscopy, but the carbon content in the samples was estimated to be less than 5% according to inductively coupled plasma-atomic emission spectrometry measurements. The distribution of boron and carbon atoms in the structure was investigated by means of 11B and 13C solid-state magic angle spinning NMR. Measurements of the magnetic susceptibility indicate a temperature-independent paramagnetism down to 20 K.
A Case Study: SystemC-Based Design of an Industrial Exposure Control Unit
2006-03-09

This article describes the modeling and refinement process of an industrial application from the automotive domain starting from a C description down to a cycle accurate SystemC model. The work was done within a co-operation between Robert Bosch GmbH, OFFIS Research Laboratory, and the University of Tübingen. The application was given by an exposure control unit from a video sensor system of a Bosch driver assistance application. The objective was to study the design flow, starting from an algorithmic C description down to synthesizable SystemC, which is the starting point for further design activities, e.g. hardware synthesis. The case study includes a comparison of the C and SystemC implementation, an analysis and a discussion of the refinement and implementation process. The fixed-point to integer data type conversion was found to be a critical task within the design process, and an automated solution is provided.
Magnetic Resonance Imaging of Renal Disease: Recent Developments and Future Applications
2006-03-10

Magnetic resonance imaging (MRI) offers the ability to non-invasively assess parenchymal and vascular renal disease. Indications for renal MRI include the evaluation of renal masses, urinary obstruction and infection, renal vasculature, and the health of transplant kidneys. The potential of MR angiography to replace invasive conventional x-ray angiography has been recognized for many years. Recent developments in MRI resulting from fast MR systems with faster gradients, new surface coil designs and the latest sequence developments coupled with innovative contrast agent administration strategies have prompted substantial progress of MRI in the diagnosis of renal disease. The goal of this article is to present the current state of MRI in diagnosing renal disease, with an emphasis on the latest developments in the evaluation of renal vascular disease.
Description of positive and negative parity dipole bands within the extended coherent state model
2006-03-10

The extended coherent state model is further extended as to describe two dipole bands of different parities. The formalism provides a consistent description of eight rotational bands. A unified description for spherical, transitional and deformed nuclei is possible. Projecting out the angular momentum and parity from a sole state, the Kπ=1+ band acquires a magnetic character, while the electric properties prevail for the other band. New signatures for a static octupole deformation are pointed out. Interesting features concerning the decay properties of the two bands are found. For illustration the formalism was applied to 172Yb and results are compared with the available data.
Conformational temperature dependence of a poly(ethylene‐co‐acrylic acid) stationary phase investigated by nuclear magnetic resonance spectroscopy and liquid chromatography
2006-03-13

Abstract A polymer‐based RP sorbent was prepared by immobilizing a poly(ethylene‐ co ‐acrylic acid) copolymer with an acid mass fraction of 5% on silica by using a 3‐glycidoxypropyl linkage. 13 C cross‐polarization/magic angle spinning NMR spectroscopy of the sorbent, either in the dry state or suspended in the mobile phase, showed an increase in mobility at elevated temperatures. Alkyl chain segments with gauche conformations were more mobile than chain segments with trans conformations. The strength of the 13 C‐ 1 H dipolar couplings in the alkyl chains was measured using the constant time dipolar and chemical shift pulse sequence, revealing less molecular motion for the trans conformation. Non‐linear van't Hoff plots were observed for separations of shape‐constrained solutes (such as geometric β‐carotene isomers and polycyclic aromatic hydrocarbons). At higher temperatures, the retention behavior was similar to that of monomeric C 18 sorbents, whereas at ambient and lower temperatures, enhanced shape‐selective properties were exhibited similar to those of polymeric C 30 sorbents.
Renal function of gene-targeted mice lacking both SGK1 and SGK3
2006-03-14

Serum- and glucocorticoid-inducible kinase (SGK) 1 and SGK3 share the ability to upregulate several ion channels, including the epithelial Na + channel. Whereas SGK1 is under genomic control of mineralocorticoids and glucocorticoids, SGK3 is constitutively expressed. The SKG1-knockout ( sgk1 −/− ) mouse is seemingly normal when it is fed a standard diet, but its ability to retain NaCl is impaired when it is fed a salt-deficient diet. In the SGK3-knockout ( sgk3 −/− ) mouse fed standard and salt-deficient diets, hair growth is strikingly delayed but NaCl excretion is normal. Thus the possibility was considered that SGK1 and SGK3 could mutually replace each other, thus preventing severe NaCl loss in sgk1 −/− and sgk3 −/− mice. We crossed SGK1- and SGK3-knockout mice and compared renal electrolyte excretion of the double mutants ( sgk1 −/− / sgk3 −/− ) with that of their wild-type littermates ( sgk1 +/+ / sgk3 +/+ ). Similar to sgk3 −/− mice, the sgk1 −/− / sgk3 −/− mice display delayed hair growth. Blood pressure was slightly, but significantly ( P &lt; 0.03), lower in sgk1 −/− / sgk3 −/− (102 ± 4 mmHg) than in sgk1 +/+ / sgk3 +/+ (114 ± 3 mmHg) mice, a difference that was maintained in mice fed low- and high-salt diets. Plasma aldosterone concentrations were significantly ( P &lt; 0.01) higher in sgk1 −/− / sgk3 −/− than in sgk1 +/+ sgk3 +/+ mice fed control (511 ± 143 vs. 143 ± 32 pg/ml) and low-salt (1,325 ± 199 vs. 362 ± 145 pg/ml) diets. During salt depletion, absolute and fractional excretions of Na + were significantly ( P &lt; 0.01) higher in sgk1 −/− / sgk3 −/− (1.2 ± 0.2 μmol/24 h g body wt, 0.12 ± 0.03%) than in sgk1 +/+ / sgk3 +/+ (0.4 ± 0.1 μmol/24 h g body wt, 0.04 ± 0.01%) mice. The sgk1 −/− / sgk3 −/− mice share the delayed hair growth with sgk3 −/− mice and the modestly impaired renal salt retention with sgk1 −/− mice. Additional lack of the isoform kinase does not substantially compound the phenotype for either property.
Stereoselective Synthesis of Protected 1,2-Diols and 1,2,3-Triols by a Tandem Hydroboration−Coupling Sequence
2006-03-14

[reaction: see text] A new approach to complex chiral diols and polyols is described utilizing a tandem hydroboration/Suzuki cross-coupling reaction. This method utilizes the versatility of a glycolate-derived chiral template.
The multidrug resistance protein 1 (Mrp1), but not Mrp5, mediates export of glutathione and glutathione disulfide from brain astrocytes
2006-03-15

Abstract Astrocytes play an important role in the glutathione (GSH) metabolism of the brain. To test for an involvement of multidrug resistance protein (Mrp) 1 and 5 in the release of GSH and glutathione disulfide (GSSG) from astrocytes, we used astrocyte cultures from wild‐type, Mrp1‐deficient [Mrp1(–/–)] and Mrp5‐deficient [Mrp5(–/–)] mice. During incubation of wild‐type or Mrp5(–/–) astrocytes, GSH accumulated in the medium at a rate of about 3 nmol/(h.mg), whereas the export of GSH from Mrp1(–/–) astrocytes was only one‐third of that. In addition, Mrp1(–/–) astrocytes had a 50% higher specific GSH content than wild‐type or Mrp5(–/–) cells. The presence of 50 μ m of the Mrp inhibitor MK571 inhibited the rate of GSH release from wild‐type and Mrp5(–/–) astrocytes by 60%, but stimulated at the low concentration of 1 μ m GSH release by 40%. In contrast, both concentrations of MK571 did not affect GSH export from Mrp1(–/–) astrocytes. Moreover, in contrast to wild‐type and Mrp5(–/–) cells, GSSG export during H 2 O 2 stress was not observed for Mrp1(–/–) astrocytes. These data demonstrate that in astrocytes Mrp1 mediates 60% of the GSH export, that Mrp1 is exclusively responsible for GSSG export and that Mrp5 does not contribute to these transport processes.
Proteasome inhibitor bortezomib modulates TLR4-induced dendritic cell activation
2006-03-15

Evidence from the animal model suggests that proteasome inhibitors may have immunosuppressive properties; however, their effects on the human immune system remain poorly investigated. Here, we show that bortezomib, a proteasome inhibitor with anticancer activity, impairs several immune properties of human monocyte-derived dendritic cells (DCs). Namely, exposure of DCs to bortezomib reduces their phagocytic capacity, as shown by FITC-labeled dextran internalization and mannose-receptor CD206 down-regulation. DCs treated with bortezomib show skewed phenotypic maturation in response to stimuli of bacterial (lipopolysaccharide [LPS]) and endogenous sources (including TNF-α and CD40L), as well as reduced cytokine production and immunostimulatory capacity. LPS-induced CCL-2/MCP-1 and CCL5/RANTES secretions by DCs were prevented by DC treatment with bortezomib. Finally, CCR7 up-regulation in DCs exposed to LPS as well as migration toward CCL19/MIP-3β were strongly impaired. As a suitable mechanism for these effects, bortezomib was found to down-regulate MyD88, an essential adaptor for TLR signaling, and to relieve LPS-induced activation of NF-κB, IRF-3, and IRF-8 and of the MAP kinase pathway. In summary, inhibition of DC function may represent a novel mechanism by which proteasome inhibitors exert immunomodulatory effects. These compounds could prove useful for tuning TLR signaling and for the treatment of inflammatory and immune-mediated disorders.
Characterization of a conduit system containing laminin-5 in the human thymus: a potential transport system for small molecules
2006-03-15

T cells develop in the thymus in a highly specialized cellular and extracellular microenvironment. The basement membrane molecule, laminin-5 (LN-5), is predominantly found in the medulla of the human thymic lobules. Using high-resolution light microscopy, we show here that LN-5 is localized in a bi-membranous conduit-like structure, together with other typical basement membrane components including collagen type IV, nidogen and perlecan. Other interstitial matrix components, such as fibrillin-1 or -2, tenascin-C or fibrillar collagen types, were also associated with these structures. Three-dimensional (3D) confocal microscopy suggested a tubular structure, whereas immunoelectron and transmission electron microscopy showed that the core of these tubes contained fibrillar collagens enwrapped by the LN-5-containing membrane. These medullary conduits are surrounded by thymic epithelial cells, which in vitro were found to bind LN-5, but also fibrillin and tenascin-C. Dendritic cells were also detected in close vicinity to the conduits. Both of these stromal cell types express major histocompatibility complex (MHC) class II molecules capable of antigen presentation. The conduits are connected to blood vessels but, with an average diameter of 2 μm, they are too small to transport cells. However, evidence is provided that smaller molecules such as a 10 kDa dextran, but not large molecules (&amp;gt;500 kDa), can be transported in the conduits. These results clearly demonstrate that a conduit system, which is also known from secondary lymphatic organs such as lymph nodes and spleen, is present in the medulla of the human thymus, and that it might serve to transport small blood-borne molecules or chemokines to defined locations within the medulla.
Modeling of Reactive Contaminant Transport in Hydraulically and Hydrogeochemically Heterogeneous Aquifers Using a Geostatistical Facies Approach
2006-03-15

It is well known that aquifer structural properties and the resulting heterogeneous distribution of hydraulic conductivity and porosity significantly control groundwater flow and spreading of solutes. In addition to this, physico-chemical aquifer heterogeneity, i.e. different intra-particle sorption and diffusion properties for different source rocks of the aquifer material (lithological components) grouped in different grain size fractions, influence the interaction of reactive solutes with the aquifer material. To be able to consider both types of heterogeneity, a new 3D finite-difference reactive solute transport modeling approach was developed, being an essential component of a methodology allowing for the upscaling of small-scale laboratory measurements and for the assessment of parameter uncertainty. Sorption and desorption are introduced at grain scale through the simulation of a retarded intra-particle diffusion process in the heterogeneous aquifer material for each lithological component and each grain size fraction in every model cell. For a practical application of the code the data needed may be introduced into each model cell following a facies-based geostatistical approach. First modeling results emphasize the strong impact of the lithological aquifer material composition and confirm the need for a geostatistical process-based reactive transport modeling approach with spatially variable hydraulic and hydrogeochemical aquifer parameters.