julilili42/papers huggingface dataset:
Absence of c‐KIT and members of the epidermal growth factor receptor family in refractory germ cell cancer
2002-07-11

Abstract BACKGROUND Germ cell tumors (GCTs) in adolescent and young males are very sensitive to cisplatin‐based chemotherapy. However, 10–20% of the patients cannot be cured by currently available therapeutic options. Once a tumor does not respond to cisplatin, current therapeutic modalities offer only a chance for short palliation. Recently, new treatment options that interfere with various receptor tyrosine kinases, including c‐KIT and members of the epidermal growth factor receptor (EGFR) family, have been used successfully in chemotherapy‐resistant tumors overexpressing c‐KIT, ERB‐B2, or EGFR. METHODS We studied the presence of c‐KIT and the four members of the EGFR family by immunohistochemistry, as well as by ERB‐B2 gene amplification using fluorescent in situ hybridization, in a series of 22 patients with cisplatin‐resistant GCTs in search of new treatment targets. The results in these refractory tumors were compared with those of 12 patients with chemosensitive GCTs diagnosed in an advanced metastatic stage. RESULTS The data obtained in both groups did not differ in any of the investigated biologic markers. c‐KIT was detected in the one case of pure seminoma studied and in the seminomatous components of combined tumors. The presence of EGFR was restricted to trophoblastic giant cells and the syncytiotrophoblastic elements of four nonseminomas including one pure choriocarcinoma and to a secondary non–germ cell malignancy, which had developed most likely from a mature teratoma. ERB‐B2 was moderately positive in the secondary non–germ cell malignancy, in one mature teratoma component of a mixed nonseminoma, and together with EGFR in the syncytiotrophoblastic cells of a pure choriocarcinoma. Of all samples investigated, this latter case was the only one showing an amplification of the ERB‐B2 gene in the syncytiotrophoblasts. ERB‐B3 and ERB‐B4 were detected rarely. CONCLUSION The majority of refractory GCTs do not qualify for treatment with new biologic agents targeting the receptor tyrosine kinases EGFR, ERB‐B2, or c‐KIT. The lack of differences between the tumors of refractory and the responsive patients indicates that overexpression of any of these receptor tyrosine kinases does not contribute to a resistant phenotype in GCTs. Cancer 2002;95:301–8. © 2002 American Cancer Society. DOI 10.1002/cncr.10671
Electrochemical Investigations on PPV Model Compounds
2002-07-11

To obtain more information on the redox behavior of poly(para-phenylenevinylene) (PPV) and its derivatives, electrochemical investigations were carried out on the short-chain PPV model compounds 1−6. The effects of different substituents were investigated by determinations of the redox potentials by cyclic voltammetry.
Zeeman tomography of magnetic white dwarfs
2002-07-12

We have computed optical Zeeman spectra of magnetic white dwarfs for field strengths between 10 and 200 MG and effective temperatures between 8000 and 40 000 K. They form a database containing 20 628 sets of flux and circular polarization spectra. A least-squares optimization code based on an evolutionary strategy can recover relatively complex magnetic field topologies from phase-resolved synthetic Zeeman spectra of rotating magnetic white dwarfs. We consider dipole and quadrupole components which are non-aligned and shifted off-centre. The model geometries include stars with a single high-field spot and with two spots separated by ~90°. The accuracy of the recovered field structure increases with the signal-to-noise ratio of the input spectra and is significantly improved if circular polarization spectra are included in addition to flux spectra. We discuss the strategies proposed so far to unravel the field geometries of magnetic white dwarfs.
Staphylococcus aureusStrains Lackingd‐Alanine Modifications of Teichoic Acids Are Highly Susceptible to Human Neutrophil Killing and Are Virulence Attenuated in Mice
2002-07-15

Staphylococcus aureus is resistant to alpha-defensins, antimicrobial peptides that play an important role in oxygen-independent killing of human neutrophils. The dlt operon mediates d-alanine incorporation into teichoic acids in the staphylococcal cell envelope and is a determinant of defensin resistance. By using S. aureus wild-type (WT) and Dlt- bacteria, the relative contributions of oxygen-dependent and -independent antimicrobial phagocyte components were analyzed. The Dlt- strain was efficiently killed by human neutrophils even in the absence of a functional respiratory burst, whereas the killing of the WT organism was strongly diminished when the respiratory burst was inhibited. Human monocytes, which do not produce defensins, inactivated the WT and Dlt- bacteria with similar efficiencies. In addition, mice injected with the Dlt- strain had significantly lower rates of sepsis and septic arthritis and fewer bacteria in the kidneys, compared with mice infected with the WT strain.
Increasing membrane contrast by means of imidazole‐osmium post‐fixation as exemplified by skeletal muscle fiber
2002-07-15

Abstract Until now, the interpretation of findings derived from investigations on membrane structures (T tubules, sarcoplasmic reticulum, the Golgi apparatus) in thick sections of mammalian muscle tissue has been limited in TEM due to the lack of sharp resolution of the membrane contours. This article shows how the imidazol‐osmium post‐fixation of tissue blocks can be used to achieve well‐contrasted, sharply defined membrane contours. Therefore, unstained sections from imidazol‐osmium post‐fixed tissue can be examined immediately. But protein structures (e.g., ribosomes) remain uncontrasted with this technique. If needed, it is possible to visualize the protein structures by conventional section staining with uranyl acetate and lead citrate. This method is suitable for both ultrathin and thick sections (&gt;150 nm). Microsc. Res. Tech. 58:121–124, 2002. © 2002 Wiley‐Liss, Inc.
LC–NMR: Theory and Experiment
2002-07-15

This chapter contains sections titled: Introduction NMR in a Flowing Liquid Design of Continuous-flow NMR Probes Experimental Arrangement For HPLC–1H NMR Coupling Practical Considerations, Solvent Suppression Techniques, Gradient Elution and Purity of HPLC Solvents References
LC–NMR for Natural Products Analysis
2002-07-15

This chapter contains sections titled: Introduction Artifact-free Isolation of Geometrical Carotenoid Isomers Analysis of Lycopene Stereoisomers in Tomato Extracts and Human Serum Identification of Lycopene Stereoisomers in Tomato Extracts Employing LC–NMR Conclusions References
Related Techniques – Introduction
2002-07-15

This chapter contains sections titled: Introduction Overview and Motivation A Short History of SFC–NMR Coupling High-pressure Flow Probes Experimental Set-up Stop- and Continuous-flow SFC–NMR Measurements Applications SFE–NMR Coupling Conclusions References
Future Developments – Introduction
2002-07-15

Presently, the vast majority of experiments are performed by using proton detection, either direct or indirect. Much valuable information could be gained by direct heteronuclear detection, and in particular, 13C NMR. One development concentrates on increasing the throughput of the NMR experiment, an ever increasingly important consideration in the pharmaceutical industry. This approach incorporates multiple, small, highly sensitive NMR detectors in a single NMR probe head. This is described in this chapter.
Related Techniques – Introduction
2002-07-15

This chapter contains sections titled: Direct Determination of Molecular Weight Distribution without Calibration Molecular Weight Dependence of Tacticity On-line GPC–NMR Analysis of Copolymers On-line GPC–NMR Analysis of Oligomers References
Accumulation of a GPI‐Anchored Protein at the Cell Surface Requires Sorting at Multiple Intracellular Levels
2002-07-16

Proteins modified by glycosylphosphatidylinositol membrane anchors have become popular for investigating the role of membrane lipid microdomains in cellular sorting processes. To this end, trypanosomatids offer the advantage that they express these molecules in high abundance. The parasitic protozoan Trypanosoma brucei is covered by a dense and nearly homogeneous coat composed of a glycosylphosphatidylinositol‐anchored protein, the variant surface glycoprotein, which is essential for survival of the parasite in the mammalian blood. Therefore, T. brucei must possess mechanisms to selectively and efficiently deliver variant surface glycoprotein to the cell surface. In this study, we have quantified the steady‐state distribution of variant surface glycoprotein by differential biotinylation, by fluorescence microscopy and by immunoelectron microscopy on high‐pressure frozen and freeze‐substituted samples. These three techniques provide very similar estimates of the fraction of variant surface glycoprotein located on the cell surface, on average 89.4%. The intracellular variant surface glycoprotein (10.6%) is predominantly located in the endosomal compartment (75%), while 25% are associated with the endoplasmic reticulum, Golgi apparatus and lysosomes. The density of variant surface glycoprotein in the plasma membrane including the membrane of the flagellar pocket, the only site for endo‐ and exocytosis in this organism, is 48–52 times higher than the density in endoplasmic reticulum membranes. The relative densities of the Golgi complex and of the endosomes are 2.7 and 10.8, respectively, compared to the endoplasmic reticulum. This data set provides the basis for an analysis of the dynamics of sorting. Depending on the intracellular itinerary of newly formed variant surface glycoprotein, the high surface density is achieved in two (endoplasmic reticulum → Golgi complex → cell surface) or three enrichment steps (endoplasmic reticulum → Golgi complex → endosomes → cell surface), suggesting sorting between several membrane compartments .
Treatment with simvastatin in normocholesterolemic patients with Alzheimer's disease: A 26‐week randomized, placebo‐controlled, double‐blind trial
2002-07-17

Abstract In a randomized, placebo‐controlled, double‐blind study, we investigated whether statins alter cholesterol metabolites and reduce Aβ levels in the cerebrospinal fluid of 44 patients with Alzheimer's disease. Individuals were given up to 80mg simvastatin daily or placebo for 26 weeks. Overall, simvastatin did not significantly alter cerebrospinal fluid levels of Aβ40 and Aβ42. In post hoc analysis, simvastatin significantly decreased Aβ40 levels in the cerebrospinal fluid of patients with mild Alzheimer's disease. The reduction of Aβ40 correlated with the reduction of 24S‐hydroxycholesterol. These changes were not observed in more severely affected patients.
Violation of energy-per-hadron scaling in resonance matter
2002-07-17

Yields of hadrons, their average masses and energies per hadron at the stage of chemical freeze-out in (ultra)relativistic heavy-ion collisions are analyzed within the statistical model. The violation of the scaling <E>/<N> = 1 GeV observed in Au+Au collisions at = 130 AGeV is linked to the formation of resonance-rich matter with a considerable fraction of baryons and antibaryons. The rise of the energy-per-hadron ratio in baryon-dominated matter is discussed. A violation of the scaling condition is predicted for a very central zone of heavy-ion collisions at energies around 40 AGeV.
Maximum entropy light source placement
2002-07-21

Several methods have been proposed to help the user to position lighting sources for a given view of a 3d-scene. In the first kind of methods the user defines a desired illumination through highlight and shadow locations for which the lighting system optimizes the light positions. The more automatic approaches are based on perceptual image metrics. [Marks et al. 1997] define an image metric that measures how different two images are perceived. A collection of maximally different images is presented to the user for selection. [Shacked and Lischinski 2001] define a perceptual based image quality metric composed of six contributing terms, for which the user has to specify weights before the system searches for a locally optimal light source placement.
Curvature driven sampling of displacement maps
2002-07-21

Displacement Mapping [Cook 1984] is commonly used in commercial rendering software for adding surface detail. In contrast to Bump Mapping not only the normal is perturbed, the surface is modified as well. A given point P on a surface is displaced to a new point P' in the direction of the surface normal of the point P, N scaled with the value stored in the Displacement Map:
Shear-Excited Sound in Magnetic Fluid
2002-07-22

Perceptible sound is shown to be excited in ferrofluids by the shear motion of a rigid plate, if the fluid is exposed to a magnetic field oblique both to the plate and to the direction of propagation. This is in contrast to other fluids, including anisotropic ones such as nematic liquids.
Proton MRS in Kennedy disease: Absolute metabolite and macromolecular concentrations
2002-07-23

Abstract Purpose To investigate whether glutamine and glutamate (Glx) were elevated in Kennedy Disease (KD), and whether pathological proteins were spectroscopically visible as altered macromolecular (MM) resonances. Materials and Methods Ten patients with KD and twelve healthy volunteers were investigated using a stimulated echo acquisition mode (STEAM) spectroscopy sequence with metabolite‐nulling. Results The concentrations of Glx remained unchanged in KD. An increased myo‐inositol (Ins), and elevated MM at 0.9 ppm were found within the motor area. The N‐acetyl‐aspartate (NAA)/creatine (Cr) ratio was negatively correlated to the number of cytosine adenosine guanine (CAG) repeats in the motor area. Conclusion The elevated MM at 0.9 ppm may be attributed to a pathologically altered protein in KD. Additionally, the changes of Ins point to a clinically unexpected involvement of the motor cortex. The correlation of NAA/Cr with the number of CAG repeats indicates a link between metabolites and genetic failure. J. Magn. Reson. Imaging 2002;16:160–167. © 2002 Wiley‐Liss, Inc.
ChemInform Abstract: New NSAR
2002-07-23

Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 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.
Expression of mRNAs of multidrug resistance proteins (Mrps) in cultured rat astrocytes, oligodendrocytes, microglial cells and neurones
2002-07-24

Abstract Multidrug resistance proteins (Mrps) are ATP‐driven export pumps that mediate the export of organic anions from cells. So far only little information is available on expression and physiological functions of Mrps in brain. The expression of mRNAs of six Mrp paralogs in rat brain, as well as in rat cultures enriched for neurones, astrocytes, oligodendrocytes and microglial cells, was studied by qualitative and semiquantitative RT‐PCR analysis. In adult rat brain as well as in neural cell cultures the mRNAs coding for Mrp1, Mrp3, Mrp4 and Mrp5 were detected. Semiquantitative analysis revealed that the mRNAs coding for Mrp1 and Mrp5 were more abundant in the four cell culture types than mRNAs of the other Mrps. mRNAs coding for Mrp3 and Mrp4 were found at significant levels in cultured astrocytes and microglial cells, whereas cultures of neurones and oligodendrocytes contained only marginal quantities of these mRNAs. Putative physiological functions of Mrps in brain cells are discussed.
Oligodendroglial cells in culture effectively dispose of exogenous hydrogen peroxide: comparison with cultured neurones, astroglial and microglial cells
2002-07-24

Abstract To investigate the antioxidative capacities of oligodendrocytes, rat brain cultures enriched for oligodendroglial cells were prepared and characterized. These cultures contained predominantly oligodendroglial cells as determined by immunocytochemical staining for the markers galactocerebroside and myelin basic protein. If oligodendroglial cultures were exposed to exogenous hydrogen peroxide (100 μ m ), the peroxide disappeared from the incubation medium following first order kinetics with a half‐time of approximately 18 min. Normalization of the disposal rate to the protein content of the cultures by calculation of the specific hydrogen peroxide detoxification rate constant revealed that the cells in oligodendroglial cultures have a 60% to 120% higher specific capacity to dispose of hydrogen peroxide than cultures enriched for astroglial cells, microglial cells or neurones. Oligodendroglial cultures contained specific activities of 133.5 ± 30.4 nmol × min −1 × mg protein −1 and 27.5 ± 5.4 nmol × min −1 × mg protein −1 of glutathione peroxidase and glutathione reductase, respectively. The specific rate constant of catalase in these cultures was 1.61 ± 0.54 min −1 × mg protein −1 . Comparison with data obtained by identical methods for cultures of astroglial cells, microglial cells and neurones revealed that all three of the enzymes which are involved in hydrogen peroxide disposal were present in oligodendroglial cultures in the highest specific activities. These results demonstrate that oligodendroglial cells in culture have a prominent machinery for the disposal of hydrogen peroxide, which is likely to support the protection of these cells in brain against peroxides when produced by these or by surrounding brain cells.
Effects of dopamine on the glutathione metabolism of cultured astroglial cells: implications for Parkinson's disease
2002-07-24

Abstract To investigate the effects of dopamine (DA) on the release of glutathione (GSH) from astrocytes, we used astroglia‐rich primary cultures from the brains of newborn rats. In the absence of DA, GSH accumulated in the medium of these cultures with a constant rate. In contrast, during incubation of the cells with 50 μ m DA extracellular GSH was not detectable anymore. This disappearance of extracellular GSH was prevented by superoxide dismutase, indicating that DA does not affect GSH release but rather reacts with the released GSH in a superoxide‐dependent reaction. Incubation of astroglial cultures with 0.5 and 1 m m DA established almost constant extracellular concentrations of H 2 O 2 of 5 μ m and 15 μ m , respectively. Under these conditions astroglial cultures release glutathione disulphide (GSSG). This GSSG export was blocked by catalase and by MK571, an inhibitor of the multidrug resistance protein 1. The effects of DA on the extracellular accumulations of GSH and GSSG were not modulated by inhibitors of DA receptors, DA transport, and monoamine oxidases. The other catecholamines adrenalineandnoradrenaline showed similar effects on the accumulation of GSH and GSSG in the medium compared with those obtained for DA. In conclusion, the data presented demonstrate that DA affects astroglial GSH metabolism by two mechanisms: (i) directly by chemical reaction with extracellular GSH, and (ii) indirectly by generation of hydrogen peroxide that leads to the efflux of GSSG from astroglial cells. These observations are discussed in the context of the brain's GSH metabolism in Parkinson's disease.
Difference in anxiety and sensitization of the acoustic startle response between the two inbred mouse strains BALB/cAN and DBA/2N
2002-07-25

The inbred mouse strain BALB has been proposed to be an animal model for pathological anxiety. BALB exhibits a stronger acoustic startle response (ASR) than the ‘less emotional’ inbred strain DBA. Four experiments were conducted to determine whether this strong ASR is due to a higher anxiety level and/or to greater sensitization in BALB than in DBA, with the following results: (1) The ASR to the very first startle stimulus was found to be much stronger in BALB than in DBA, and freezing behavior evoked by startle stimuli was more pronounced in BALB than in DBA. These findings indicate a higher level of anxiety in this strain. (2) ASR amplitudes of BALB initially rose much higher during consecutive startle stimuli and remained at a high level much longer than in DBA. Thereafter, ASR amplitude dropped more slowly and to a lesser degree than in DBA. Startle amplitudes decreased similarly in both strains (strong exponential decrease) only when a low sound pressure level (SPL) was used which elicited approximately the same low ASR in both strains. These results can only be explained by increased sensitization in BALB. (3) The slope of the i/o‐function, which represents the relation between sensory input and motor output, was steeper in BALB than in DBA. As it has been shown recently, sensitization increases the slope of the startle i/o‐function indicating increased sensitization in BALB. It is discussed, however, whether anxiety also contributes to this effect. (4) Footshocks increased the ASR much less in BALB than in DBA, again showing increased sensitization in BALB. Both a higher level of anxiety and greater sensitization therefore determined the greater strength of the ASR in BALB than in DBA.
Classifications of families of homologous organic compounds based on energy by means of ab initio HF, MP2 and DFT optimizations
2002-07-25

Abstract A method is suggested for combining the quantum chemical principle of isolated molecules and the systematics of homologous families for different functional groups in traditional organic chemistry. The classification of organic compounds is performed by statistical treatments of fundamental quantum mechanical quantities such as total and partial energies. We used the total energies (computed by DFT BLYP and B3LYP, HF and MP2 methods, which are size‐extensive, applying the 6–31 G** and some other basis sets) of isolated molecules obtained by gradient optimizations to classify homologous series of organic compounds by linear least‐squares regressions versus the total number of electrons. Two numerical parameters, slope ( h ) and intercept ( s ), are obtained characterizing each family of homologous compounds. Families of for example 17 different functional groups of the same CH 2 ‐homologous unit are grouped on parallel lines with the same slope h , differing only in their s parameters. Isomeric compounds differ in their s values if they belong to the same homologous unit. Compounds of other homologous units (conjugated alkenes, cumulenes and benzenoides) are found with different slopes h on regression lines. Energy partitioning leads also to linear regressions of different statistical accuracy for the components which add fully to the observed h and s parameters. The h and s parameters allow the prediction of unknown total energies of homologous compounds from total energies of a subset of smaller compounds which belong to the same homologous family. Likewise, atomization energies can be predicted using the derived h and s parameters. Copyright © 2002 John Wiley &amp; Sons, Ltd.