julilili42/papers huggingface dataset:
Faculty Opinions recommendation of Juvenile pilocytic astrocytomas do not undergo spontaneous malignant transformation: grounds for designation as hamartomas.
2008-09-17

AIM: To determine whether juvenile pilocytic astrocytomas WHO grade I have the potential for spontaneous malignant transformation.METHODS: A literature search was performed, cross-referencing juvenile pilocytic astrocytoma, pilocytic astrocytoma, astrocytoma grade I, optic glioma, glioma, low-grade gliomas, polar spongioblastoma, gliocytoma embryonale, and malignant transformation, anaplasia or anaplastic change. Bibliographic PubMed and Google searches were performed, and reference ophthalmology and neuropathology textbooks were utilised.RESULTS: A total of 52 purported cases of malignant transformation were found. Twenty-two of these tumours, however, did not initially match criteria for juvenile pilocytic astrocytoma WHO grade I and were excluded. Six other cases were located within the irradiated field but represented anaplasias developing independently of the primary tumour. The remaining 24 malignancies had all been previously irradiated.CONCLUSION: Juvenile pilocytic astrocytomas WHO grade I do not undergo spontaneous anaplastic transformation. Malignant transformations have only been demonstrated following radiation therapy. Earlier clinical and histopathological opinions regarding juvenile pilocytic astrocytomas as hamartomatous lesions are reaffirmed. PMID: 17962395
Foraging bats avoid noise
2008-09-19

SUMMARY Ambient noise influences the availability and use of acoustic information in animals in many ways. While much research has focused on the effects of noise on acoustic communication, here, we present the first study concerned with anthropogenic noise and foraging behaviour. We chose the greater mouse-eared bat (Myotis myotis) as a model species because it represents the especially vulnerable group of gleaning bats that rely on listening for prey rustling sounds to find food (i.e. `passive listening'). In a choice experiment with two foraging compartments, we investigated the influence of background noise on foraging effort and foraging success. We tested the hypotheses that: (1) bats will avoid foraging areas with particularly loud background noise; and (2) the frequency–time structure of the noise will determine, in part, the degree to which it deters bats. We found a clear effect of the type of noise on the allocation of foraging effort to the compartments and on the distribution of prey capture events. When playing back silence, the bats made equal use of and were equally successful in both compartments. In the other three treatments (where a non-silent sound was played back), the bats avoided the playback compartment. The degree to which the background noise deterred bats from the compartment increased from traffic noise to vegetation movement noise to broadband computer-generated noise. Vegetation noise, set 12 dB below the traffic noise amplitude, had a larger repellent effect; presumably because of its acoustic similarity with prey sounds. Our experimental data suggest that foraging areas very close to highways and presumably also to other sources of intense, broadband noise are degraded in their suitability as foraging areas for such `passive listening'bats.
Natural Surfactant-Based Emulsion Systems: The Influence of Common Pharmaceutical Excipients on Colloidal Structure and Physical Stability
2008-09-19

There is a growing need for research into new skin- and environment-friendly surfactants. The aim of the study was to find out whether a combination of an alkylpolyglucoside natural surfactant with established pharmaceutical excipients could provide a solid pharmaceutical base with satisfied physical stability. The study was carried out in two phases: the first one focused on the colloidal structure of vehicles formulated with oils of different polarity and/or different costabilizer (lipophilic versus hydrophilic) and the second one evaluated vehicles' physical stability. A number of techniques were used (polarization, light, and transmission electron microscopy, pH, conductivity and thermogravimetric measurements, rheological analysis and cyclic temperature stress test). Natural surfactant's interaction with used excipients resulted in the formation of semisolid emulsion systems of different rheological profiles, stabilized predominantly by synergistic effects of lamellar liquid-crystalline (L alpha) and complex lamellar gel (L beta) phases. The type of used oil and costabilizer significantly influenced the colloidal structure of the vehicles, particularly in terms of water distribution mode and initial rheological performance as well as their physical stability. It was recommended that medium polar oils of ester type and lipophilic costabilizers, particularly long chain fatty alcohols, should be used in the formulation of stable alkylpolyglucoside-based topical vehicles.
Alr0397 Is an Outer Membrane Transporter for the Siderophore Schizokinen inAnabaenasp. Strain PCC 7120
2008-09-20

ABSTRACT Iron uptake in proteobacteria by TonB-dependent outer membrane transporters represents a well-explored subject. In contrast, the same process has been scarcely investigated in cyanobacteria. The heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 is known to secrete the siderophore schizokinen, but its transport system has remained unidentified. Inspection of the genome of strain PCC 7120 shows that only one gene encoding a putative TonB-dependent iron transporter, namely alr0397, is positioned close to genes encoding enzymes involved in the biosynthesis of a hydroxamate siderophore. The expression of alr0397, which encodes an outer membrane protein, was elevated under iron-limited conditions. Inactivation of this gene caused a moderate phenotype of iron starvation in the mutant cells. The characterization of the mutant strain showed that Alr0397 is a TonB-dependent schizokinen transporter (SchT) of the outer membrane and that alr0397 expression and schizokinen production are regulated by the iron homeostasis of the cell.
Two Distinctive Granite Suites in the SW Bohemian Massif and their Record of Emplacement: Constraints from Geochemistry and Zircon 207Pb/206Pb Chronology
2008-09-20

Various types of gneisses, migmatites and granites dominate the outcrops of the Bavarian Forest, in the southwestern Moldanubian Sector of the Bohemian Massif, providing evidence for the geological characteristics of a crustal root zone. Fourteen granite intrusions from this area have been dated by the single-zircon Pb-evaporation technique. Major and trace elements, and Rb–Sr and Sm–Nd isotope compositions of these rocks have also been determined. The 207Pb/206Pb single-zircon ages indicate Carboniferous magma production in only a few million years. The intrusions NE of the Bavarian Pfahl Zone are dated between 328 and 321 Ma, whereas ages between 324 and 321 Ma are obtained in the area SW of this zone. The coincidence between these ages and regional peak-metamorphism in this area (‘Bavarian Phase’) indicates a connection between metamorphism and melt extraction. When the geochemical and isotopic compositions of the granites are examined, supplemented by data from previous geochemical studies, it becomes evident that the Bavarian Pfahl Zone, which runs diagonally across the Bavarian Forest, is a terrane boundary that separates two regions of peraluminous S-type plutons predominantly of crustal anatectic origin but with distinct compositional features. Plutons located in the SW and along the Pfahl Zone (Bavarian Terrane) define a high Ca–Sr–Y suite, whereas plutons from the NE and neighbouring crystalline units (Ostrong Terrane) constitute a low Ca–Sr–Y suite. Granites from the Bavarian Terrane have significantly more radiogenic initial Nd and less radiogenic initial Sr isotope ratios than granites from the Ostrong Terrane, indicative of different source materials. These findings support the idea that the difference in magma composition is linked to the nature of the underlying crust.
Enantiomeric Separation of Several Oxirane Derivatives by High Performance Liquid Chromatography on Polysaccharide-Based Chiral Stationary Phases
2008-09-20

Five polysaccharide based chiral stationary phases have been used for separation of enantiomers of fourteen heterocyclic oxiranes. The polysaccharide based chiral stationary phases used in this study are Chiralak AD, Chiralpak AS, Chiralcel OD, Chiralcel OG, and Chiralcel OJ. From the chiral separation results, the chiral separation ability for the selected compounds show the order of Chiralpak AD > Chiralcel OD > Chiralcel OJ > Chiralcel OG > Chiralpak AS. Chiralcel OD appears to be quite versatile, since 8 out of 11 oxiranes with π-aromatic system were successfully resolved, yet no resolution was obtained for those oxirane derivatives, which lacks the π-aromatic system. Although Chiralcel OD is also versatile, it was not as effective; since the separation factors (α) are much smaller. The results indicate that dipole interactions have a strong impact on the retention mechanism, and extended π systems are essential. The spatial arrangement of the substituent groups around the analyte stereogenic center plays an important role in enantiomeric separations. The closer a group is to the chiral center, the more likely is the chiral recognition and enantioselectivity.
Htdp and dmda in the battlefield
2008-09-21

Teaching the introductory course on programming is hard, even with well-proven didactic methods and material. This is a report on the first-year programming course taught at Tübingen and Freiburg universities. The course builds on the well-developed systematic approaches using functional programming, pioneered by the PLT group. In recent years, we have introduced novel approaches to the teaching process itself. In particular, assisted programming sessions gave the students a solid basis for developing their programming skills. In this paper we trace the development of our approach. Furthermore, we have collected information on how well our course had worked, and how the results together with our experience gained over years have lead to substantial, measurable improvements.
Physiology of phototrophic iron(II)-oxidizing bacteria: implications for modern and ancient environments
2008-09-22

Phototrophic iron(II) [Fe(II)]-oxidizing bacteria are present in modern environments and evidence suggests that this metabolism was present already on early earth. We determined Fe(II) oxidation rates depending on pH, temperature, light intensity, and Fe(II) concentration for three phylogenetically different phototrophic Fe(II)-oxidizing strains (purple nonsulfur bacterium Rhodobacter ferrooxidans sp. strain SW2, purple sulfur bacterium Thiodictyon sp. strain F4, and green sulfur bacterium Chlorobium ferrooxidans strain KoFox). While we found the overall highest Fe(II) oxidation rates with strain F4 (4.5 mmol L−1 day−1, 800 lux, 20 °C), the lowest light saturation values [at which maximum Fe(II) oxidation occurred] were determined for strain KoFox with light saturation already below 50 lux. The oxidation rate per cell was determined for R. ferrooxidans strain SW2 to be 32 pmol Fe(II) h−1 per cell. No significant toxic effect of Fe(II) was observed at Fe(II) concentrations of up to 30 mM. All three strains are mesophiles with upper temperature limits of c. 30 °C. The main pigments were identified to be spheroidene, spheroidenone, OH-spheroidenone (SW2), rhodopinal (F4), and chlorobactene (KoFox). This study will improve our ecophysiological understanding of iron cycling in modern environments and will help to evaluate whether phototrophic iron oxidizers may have contributed to the formation of Fe(III) on early earth.
ChemInform Abstract: Three‐Component Combinatorial Synthesis of Novel Dihydropyrano[2,3‐c]pyrazoles.
2008-09-22

Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Boundaries of Dachsous Cadherin activity modulate the Hippo signaling pathway to induce cell proliferation
2008-09-23

The conserved Hippo tumor suppressor pathway is a key signaling pathway that controls organ size in Drosophila . To date a signal transduction cascade from the Cadherin Fat at the plasma membrane into the nucleus has been discovered. However, how the Hippo pathway is regulated by extracellular signals is poorly understood. Fat not only regulates growth but also planar cell polarity, for which it interacts with the Dachsous (Ds) Cadherin, and Four-jointed (Fj), a transmembrane kinase that modulates the interaction between Ds and Fat. Ds and Fj are expressed in gradients and manipulation of their expression causes abnormal growth. However, how Ds and Fj regulate growth and whether they act through the Hippo pathway is not known. Here, we report that Ds and Fj regulate Hippo signaling to control growth. Interestingly, we found that Ds/Fj regulate the Hippo pathway through a remarkable logic. Induction of Hippo target genes is not proportional to the amount of Ds or Fj presented to a cell, as would be expected if Ds and Fj acted as traditional ligands. Rather, Hippo target genes are up-regulated when neighboring cells express different amounts of Ds or Fj. Consistent with a model that differences in Ds/Fj levels between cells regulate the Hippo pathway, we found that artificial Ds/Fj boundaries induce extra cell proliferation, whereas flattening the endogenous Ds and Fj gradients results in growth defects. The Ds/Fj signaling system thus defines a cell-to-cell signaling mechanism that regulates the Hippo pathway, thereby contributing to the control of organ size.
Comprehensive study of proteasome inhibitors against Plasmodium falciparum laboratory strains and field isolates from Gabon
2008-09-24

Abstract Background The emergence and spread of Plasmodium falciparum resistance to almost all available antimalarial drugs necessitates the search for new chemotherapeutic compounds. The ubiquitin/proteasome system plays a major role in overall protein turnover, especially in fast dividing eukaryotic cells including plasmodia. Previous studies show that the 20S proteasome is expressed and catalytically active in plasmodia and treatment with proteasome inhibitors arrests parasite growth. This is the first comprehensive screening of proteasome inhibitors with different chemical modes of action against laboratory strains of P. falciparum . Subsequently, a selection of inhibitors was tested in field isolates from Lambaréné, Gabon. Methods Epoxomicin, YU101, YU102, MG132, MG115, Z-L 3 -VS, Ada-Ahx 3 -L 3 -VS, lactacystin, bortezomib (Velcade ® ), gliotoxin, PR11 and PR39 were tested and compared to chloroquine- and artesunate-activities in a standardized in vitro drug susceptibility assay against P. falciparum laboratory strains 3D7, D10 and Dd2. Freshly obtained field isolates from Lambaréné, Gabon, were used to measure the activity of chloroquine, artesunate, epoxomicin, MG132, lactacystin and bortezomib. Parasite growth was detected through histidine-rich protein 2 (HRP2) production. Raw data were fitted by a four-parameter logistic model and individual inhibitory concentrations (50%, 90%, and 99%) were calculated. Results Amongst all proteasome inhibitors tested, epoxomicin showed the highest activity in chloroquine-susceptible (IC50: 6.8 nM [3D7], 1.7 nM [D10]) and in chloroquine-resistant laboratory strains (IC50: 10.4 nM [Dd2]) as well as in field isolates (IC50: 8.5 nM). The comparator drug artesunate was even more active (IC50: 1.0 nM), whereas all strains were chloroquine-resistant (IC50: 113 nM). Conclusion The peptide α',β'-epoxyketone epoxomicin is highly active against P. falciparum regardless the grade of the parasite's chloroquine susceptibility. Therefore, inhibition of the proteasome is a highly promising strategy to develop new antimalarials. Epoxomicin can serve as a standard to compare new inhibitors with species-specific activity.
Dependence of Hearing Changes on the Dose of Intratympanically Applied Gentamicin: A Meta‐Analysis Using Mathematical Simulations of Clinical Drug Delivery Protocols
2008-09-24

Abstract Objectives/Hypothesis: To establish safe dosing protocols for the treatment of patients with Meniere's disease with intratympanic gentamicin. Study Design: A validated computer model of gentamicin dispersion in the inner ear fluids was used to calculate cochlear drug levels resulting from specific clinical delivery protocols. Dosing in the cochlea was compared with changes of hearing sensitivity for 568 patients reported in 19 publications. Methods: Cochlear drug levels were calculated based on the concentration and volume of gentamicin applied, the time the drug remained in the middle ear, and on the specific timing of injections. Time courses were quantified in terms of the maximum concentration ( C max ) and the area under the curve of the drug at specific cochlear locations. Results: Drug levels resulting from single, “one‐shot” injections were typically lower than those from repeated or continuous application protocols. Comparison of hearing sensitivity changes with gentamicin dosing revealed a flat curve with a near‐zero mean for lower doses, suggesting that hearing changes with doses over this range were probably unrelated to the applied drug. Higher intracochlear doses were generated with repeated or continuous delivery protocols, which in some cases caused substantial hearing losses and an increased incidence of deafened ears. Conclusions: One‐shot application protocols produce gentamicin doses in the cochlea that have minimal risk to hearing at the frequencies tested. Repeated or continuous application protocols result in higher doses that in some cases damage hearing. The high variability of hearing changes, even with low gentamicin doses, calls into question the rationale for using individual hearing changes to titrate the applied dose.
Oscillations of rapidly rotating relativistic stars
2008-09-25

Nonaxisymmetric oscillations of rapidly rotating relativistic stars are studied using the Cowling approximation. The oscillation spectra have been estimated by Fourier transforming the evolution equations describing the perturbations. This is the first study of its kind and provides information on the effect of fast rotation on the oscillation spectra while it offers the possibility of studying the complete problem by including space-time perturbations. Our study includes both axisymmetric and nonaxisymmetric perturbations and provides limits for the onset of the secular bar mode rotational instability. We also present approximate formulas for the dependence of the oscillation spectrum from rotation. The results suggest that it is possible to extract the relativistic star's parameters from the observed gravitational wave spectrum.
Modification of Born impurity scattering near the surface ofd-wave superconductors and influence of external magnetic field
2008-09-25

We study the influence of Born impurity scattering on the zero-energy Andreev bound states near the surface of a d-wave superconductor with and without an externally applied magnetic field. Without an external magnetic field we show that the effect of Born impurity scattering is stronger at the surface than in the bulk. In the presence of an external magnetic field the splitting of the zero-energy Andreev bound states is shown to have a nonmonotonous temperature dependence. Born impurity scattering does not wash out the peak splitting, but instead the peak splitting is shown to be quite robust against impurities. We also show that a nonzero gap renormalization appears near the surface.
Mitochondrial potassium channel Kv1.3 mediates Bax-induced apoptosis in lymphocytes
2008-09-26

The potassium channel Kv1.3 has recently been located to the inner mitochondrial membrane of lymphocytes. Here, we show that mouse and human cells that are genetically deficient in either Kv1.3 or transfected with siRNA to suppress Kv1.3-expression resisted apoptosis induced by several stimuli, including Bax over-expression. Retransfection of either Kv1.3 or a mitochondrial-targeted Kv1.3 restored cell death. Bax interacted with and functionally inhibited mitochondrial Kv1.3. Incubation of isolated Kv1.3-positive mitochondria with recombinant Bax, t-Bid, or toxins that bind to and inhibit Kv1.3 successively triggered hyperpolarization, formation of reactive oxygen species, release of cytochrome c , and marked depolarization. Kv1.3-deficient mitochondria were resistant to Bax, t-Bid, and the toxins. Mutation of Bax at K128, which corresponds to a conserved lysine in Kv1.3-inhibiting toxins, abrogated its effects on both Kv1.3 and mitochondria. These findings suggest that Bax mediates cytochrome c release and mitochondrial depolarization in lymphocytes, at least in part, via its interaction with mitochondrial Kv1.3.
High-Speed X-ray Cineradiography for Analyzing Complex Kinematics in Living Insects
2008-09-26

More than one hundred years ago, Lucien Bull showed, by means of his famous high-speed cinematographic movies of living species, the outstanding scientific value of time-resolved imaging, e.g. to understand the mechanisms behind insect flight [1 Bull, L. 1928. La Cinématographie, Paris: Armand Collin. [Google Scholar]]. For X-ray imaging, synchrotron light sources offer a photon beam that (i) propagates quasi-parallel, (ii) has fluxes that are higher by orders of magnitude than laboratory sources, and (iii) allows one to exploit more sophisticated contrast modalities. The use of synchrotron light is thus the next step in fast-imaging development: high-speed hard X-ray cineradiography employing phase contrast mechanisms [2 Westneat, M. W., Socha, J. J. and Lee, W.-K. 2008. Advances in biological structure, function, and physiology using synchrotron X-ray imaging. Annu. Rev. Physiol., 70: 119–42. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar],3 Westneat, M.W., Betz, O., Blob, R.W., Fezzaa, K., Cooper, W.J. and Lee, W.-K. 2003. Tracheal respiration in insects visualized with synchrotron X-ray imaging. Science, 299: 558–560. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]]. Imaging with X-rays offers the chance to investigate complex kinematics of, for example, feeding and locomotion devices of animals, as the penetrating nature of the radiation reveals internal information.
Amygdala activation during reading of emotional adjectives—an advantage for pleasant content
2008-09-27

This event-related functional magnetic resonance imaging (fMRI) study investigated brain activity elicited by emotional adjectives during silent reading without specific processing instructions. Fifteen healthy volunteers were asked to read a set of randomly presented high-arousing emotional (pleasant and unpleasant) and low-arousing neutral adjectives. Silent reading of emotional in contrast to neutral adjectives evoked enhanced activations in visual, limbic and prefrontal brain regions. In particular, reading pleasant adjectives produced a more robust activation pattern in the left amygdala and the left extrastriate visual cortex than did reading unpleasant or neutral adjectives. Moreover, extrastriate visual cortex and amygdala activity were significantly correlated during reading of pleasant adjectives. Furthermore, pleasant adjectives were better remembered than unpleasant and neutral adjectives in a surprise free recall test conducted after scanning. Thus, visual processing was biased towards pleasant words and involved the amygdala, underscoring recent theoretical views of a general role of the human amygdala in relevance detection for both pleasant and unpleasant stimuli. Results indicate preferential processing of pleasant information in healthy young adults and can be accounted for within the framework of appraisal theory.