julilili42/papers huggingface dataset:
Posters
2000-07-17

This chapter contains sections titled: Induction of Unscheduled DNA Synthesis by the Mycotoxin Ochratoxin A in Cultured Urothelial Cells from Pigs and Humans In vitro Covalent Binding as a Possible Quantitative Indicator for the Genotoxic Potency of Aflatoxin B1 in Rat and Human N-Palmitoyl-HFB1: A New Metabolite of Hydrolyzed Fumonisin (HFB1) in Rat Liver Microsomes Are Nitroso Bile Acids Involved in Carcinogenesis Following Reflux of Duodenal Juice? The Occurrence of Heterocyclic Aromatic Amines in Various Food Samples Analyzed by High Performance Liquid Chromatography-Electrospray Tandem Mass Spectrometry (HPLC-ESI- MS/MS) Determination of HAAs in Samples with Strong Matrix Influences Activation of Nitrosamines in Metabolically Proficient Cell Systems to Induce Cytotoxic and Genotoxic Effects 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) Suppresses Apoptosis in the Livers of c-myc Transgenic Mice and in Rat Hepatocytes in Primary Culture Metabolism of Benzo[c]phenanthrene and Genotoxicity of the Corresponding Dihydrodiols After Activation by Human Cytochrome P450-Enzymes in Comparison to Dibenzo[a,l]pyrene-11,12- dihydrodiol and Benzo[a]pyrene-7,8-dihydrodiol In vitro Toxicity and Microsomal Metabolism of the Polycyclic Musk Fixolide and Crysolide Special Effects of α,β-Unsaturated Aldehydes in Human Lymphocytes Studied by Premature Chromosome Condensation (PCC) Determination of Apoptosis and Mutagenic Effects of 2-Cyclohexen-1-one in Human Leukemic Cell Lines and Peripheral Blood Lymphocytes Food Relevant α,β-Unsaturated Carbonyl Compounds: In vitro Toxicity, Genotoxic (Mutagenic) Effectiveness and Reactivity Towards Glutathione Enantioselective Metabolic Activation of Safrole Inhibition of DNA Repair Processes by Inorganic Arsenic Identification of Antiandrogens with Functional Transactivation in vitro Assays and Molecular Modeling Analysis Oxidative Metabolism and Genotoxicity of Enterolactone and Enterodiol Genotoxic Potential of Isoflavone and Coumestane Phytoestrogens Study on Mechanisms by Which Carrot and Tomato Juice May Reduce Oxidative DNA-Damages in vivo: in vitro Effects of All-trans-β-Carotene and Lycopene Carotenoids and Vitamin D: Micronutrients Capable to Stimulate Gap Junctional Communication Protective Effects of Vitamins C and E in Smokers Monitored by Ascorbyl Radical Formation in Plasma and the Frequency of Micronuclei in Lymphocytes Anticarcinogenic Effects of Genotoxic Carcinogens Based on Cell-Cycle Delay, Calculated for the Two-Stage Clonal Expansion Model of Carcinogenesis Occurrence of Emodin, Chrysophanol and Physcion in Vegetables, Herbs and Liquors. Genotoxicity and Anti-Genotoxicity of the Anthraquinones and of the Whole Plants Degradation of Flavonoids by the Human Intestinal Bacteria Eubacterium Ramulus and Enterococcus Casseliflavus Distribution Kinetics of a Flavonoid Extract in the Gastrointestinum of Rats Flavones and Inhibition of Tumor Cell Growth: New Aspects on the Mechanism of Action Food Derived Flavonoids That Affect Proliferation, Differentiation and Apoptosis in Human Colon Carcinoma Cells (HT-29) and Their Mode of Action
<title>X-ray pn-CCDs on the XMM Newton Observatory</title>
2000-07-18

XMM-Newton, the most powerful X-ray telescope ever built was launched from the european space port Kourou on december 10 last year. Three large X-ray Wolter type mirror systems are focusing the incoming X-rays from 100 eV up to 15,000 eV onto the focal instruments: fully depleted backside illuminated pn-CCDs and frontside illuminated MOS-CCDs. The concept of the pn-CCD camera will be briefly described and its performance on ground and in orbit will be shown. Special emphasis will be given to the radiation hardening of the devices, to the instrument background and to the experience of charged particle background in space. A comparison of the performance on ground and after 5 months in space will be shown.
<title>In-orbit performance of the EPIC-PN CCD camera on board XMM-Newton</title>
2000-07-18

On 10th December 1999, the European X-ray satellite XMM, now called XMM-Newton, was successfully put into orbit. After initial commissioning of the satellite's subsystems, the EPIC-pn camera was switched on and tested thoroughly in the period Jan./Febr. 2000. After refining of some of the parameter settings and the on-board pn-computer programs, we started the Calibration and Performance Verification Phase, which will last until the end of May 2000. In this paper we report on the results of the EPIC-pn Commissioning Phase with respect to the in-orbit performance of the camera. We also show some of the early results with the pn-camera, the first light image of a region in the Large Magellanic Cloud, and an observation of the Crab Nebular.
<title>Description of the FAR-XITE (Fine Angular Resolution X-ray Imaging TelescopE, "far-sight") optics and science objectives: an update</title>
2000-07-18

The FAR.XITE is a proposed balloon payload. After a test flight, our initial goal is to fly 10 nested mirror modules, but then even more modules can be added until the mass limit of the pointing system and balloon gondola are reached. These limits are yet to be determined. In our design, Wolter I mirrors are coated with multilayers that allow FAR.XITE to reach 100 keV with better than 1 arc minute angular resolution. We summarize the science objectives, optical design and specifications that were previously reported, and present our recent results of advances in X-ray mirror and detector.
The heterodimeric amino acid transporter 4F2hc/y+LAT2 mediates arginine efflux in exchange with glutamine
2000-07-25

The cationic amino acid arginine, due to its positive charge, is usually accumulated in the cytosol. Nevertheless, arginine has to be released by a number of cell types, e.g. kidney cells, which supply other organs with this amino acid, or the endothelial cells of the blood–brain barrier which release arginine into the brain. Arginine release in mammalian cells can be mediated by two different transporters, y+LAT1 and y+LAT2. For insertion into the plasma membrane, these transporters have to be associated with the type-II membrane glycoprotein 4F2hc [Torrents, Estevez, Pineda, Fernandez, Lloberas, Shi, Zorzano and Palacin (1998) J. Biol. Chem. 273, 32437–32445]. The present study elucidates the function and distribution of y+LAT2. In contrast to y+LAT1, which is expressed mainly in kidney epithelial cells, lung and leucocytes, y+LAT2 has a wider tissue distribution, including brain, heart, testis, kidney, small intestine and parotis. When co-expressed with 4F2hc in Xenopus laevis oocytes, y+LAT2 mediated uptake of arginine, leucine and glutamine. Arginine uptake was inhibited strongly by lysine, glutamate, leucine, glutamine, methionine and histidine. Mutual inhibition was observed when leucine or glutamine was used as substrate. Inhibition of arginine uptake by neutral amino acids depended on the presence of Na+, which is a hallmark of y+LAT-type transporters. Although arginine transport was inhibited strongly by glutamate, this anionic amino acid was only weakly transported by 4F2hc/y+LAT2. Amino acid transport via 4F2hc/y+LAT2 followed an antiport mechanism similar to the other members of this new family. Only preloaded arginine could be released in exchange for extracellular amino acids, whereas marginal release of glutamine or leucine was observed under identical conditions. These results indicated that arginine has the highest affinity for the intracellular binding site and that arginine release may be the main physiological function of this transporter.
Vacuum polarization in QED with world-line methods
2000-07-27

Motivated by several recent papers on string-inspired calculations in QED, we\\nhere present our own use of world-line techniques in order to calculate the\\nvacuum polarization and effective action in scalar and spinor QED with external\\narbitrary constant electromagnetic field configuration.\\n
Trichome morphogenesis inArabidopsis
2000-07-29

Trichomes (plant hairs) in Arabidopsis thaliana are large non–secreting epidermal cells with a characteristic three–dimensional architecture. Because trichomes are easily accessible to a combination of genetic, cell biological and molecular methods they have become an ideal model system to study various aspects of plant cell morphogenesis. In this review we will summarize recent progress in the understanding of trichome morphogenesis.
Acid sphingomyelinase is involved in CEACAM receptor‐mediated phagocytosis of Neisseria gonorrhoeae
2000-07-31

The interaction with human phagocytes is a hallmark of symptomatic Neisseria gonorrhoeae infections. Gonococcal outer membrane proteins of the Opa family induce the opsonin‐independent uptake of the bacteria that relies on CEACAM receptors and an active signaling machinery of the phagocyte. Here, we show that CEACAM receptor‐mediated phagocytosis of Opa 52 ‐expressing N. gonorrhoeae into human cells results in a rapid activation of the acid sphingomyelinase. Inhibition of this enzyme by imipramine or SR33557 abolishes opsonin‐independent internalization without affecting bacterial adherence. Reconstitution of ceramide, the product of acid sphingomyelinase activity, in imipramine‐ or SR33557‐treated cells restores internalization of the bacteria. Furthermore, we demonstrate that CEACAM receptor‐initiated stimulation of other signalling molecules, in particular Src‐like tyrosine kinases and Jun N‐terminal kinases, requires acid sphingomyelinase. These studies provide evidence for a crucial role of the acid sphingomyelinase for CEACAM receptor‐initiated signalling events and internalization of Opa 52 ‐expressing N. gonorrhoeae into human neutrophils.
Glutathione, oxidative stress and neurodegeneration
2000-08-01

There is significant evidence that the pathogenesis of several neurodegenerative diseases, including Parkinson's disease, Alzheimer's disease, Friedreich's ataxia and amyotrophic lateral sclerosis, may involve the generation of reactive oxygen species and mitochondrial dysfunction. Here, we review the evidence for a disturbance of glutathione homeostasis that may either lead to or result from oxidative stress in neurodegenerative disorders. Glutathione is an important intracellular antioxidant that protects against a variety of different antioxidant species. An important role for glutathione was proposed for the pathogenesis of Parkinson's disease, because a decrease in total glutathione concentrations in the substantia nigra has been observed in preclinical stages, at a time at which other biochemical changes are not yet detectable. Because glutathione does not cross the blood–brain barrier other treatment options to increase brain concentrations of glutathione including glutathione analogs, mimetics or precursors are discussed.
Glutathione metabolism in brain
2000-08-01

The cells of the adult human brain consume ≈ 20% of the oxygen utilized by the body although the brain comprises only 2% of the body weight. Reactive oxygen species, which are produced continuously during oxidative metabolism, are generated at high rates within the brain. Therefore, the defense against the toxic effects of reactive oxygen species is an essential task within the brain. An important component of the cellular detoxification of reactive oxygen species is the antioxidant glutathione. The main focus of this short review is recent results on glutathione metabolism of brain astrocytes and neurons in culture. These two types of cell prefer different extracellular precursors for glutathione. Glutathione is involved in the disposal of exogenous peroxides by astrocytes and neurons. In coculture astrocytes protect neurons against the toxicity of reactive oxygen species. One mechanism of this interaction is the supply by astrocytes of glutathione precursors to neurons.
A New Subfamily of Sucrose Transporters, SUT4, with Low Affinity/High Capacity Localized in Enucleate Sieve Elements of Plants
2000-08-01

A new subfamily of sucrose transporters from Arabidopsis (AtSUT4), tomato (LeSUT4), and potato (StSUT4) was isolated, demonstrating only 47% similarity to the previously characterized SUT1. SUT4 from two plant species conferred sucrose uptake activity when expressed in yeast. The K(m) for sucrose uptake by AtSUT4 of 11.6 +/- 0.6 mM was approximately 10-fold greater than for all other plant sucrose transporters characterized to date. An ortholog from potato had similar kinetic properties. Thus, SUT4 corresponds to the low-affinity/high-capacity saturable component of sucrose uptake found in leaves. In contrast to SUT1, SUT4 is expressed predominantly in minor veins in source leaves, where high-capacity sucrose transport is needed for phloem loading. In potato and tomato, SUT4 was immunolocalized specifically to enucleate sieve elements, indicating that like SUT1, macromolecular trafficking is required to transport the mRNA or the protein from companion cells through plasmodesmata into the sieve elements.
The Zinc-responsive Regulator Zur and Its Control of theznu Gene Cluster Encoding the ZnuABC Zinc Uptake System in Escherichia coli
2000-08-01

The synthesis of the Escherichia coli zinc transporter, encoded by the znuACB gene cluster, is regulated in response to the intracellular zinc concentration by the zur gene product. Inactivation of the zur gene demonstrated that Zur acts as a repressor when binding Zn(2+). Eight chromosomal mutant zur alleles were sequenced to correlate the loss of Zur function with individual mutations. Wild-type Zur and ZurDelta46-91 formed homo- and heterodimers. Dimerization was independent of metal ions since it also occurred in the presence of metal chelators. Using an in vivo titration assay, the znu operator was narrowed down to a 31-base pair region overlapping the translational start site of znuA. This location was confirmed by footprinting assays. Zur directly binds to a single region comprising a nearly perfect palindrome. Zinc chelators completely inhibited and Zn(2+) in low concentrations enhanced DNA binding of Zur. No evidence for autoregulation of Zur was found. Zur binds at least 2 zinc ions/dimer specifically. Although most of the mutant Zur proteins bound to the znu operator in vitro, no protection was observed in in vivo footprinting experiments. Analysis of the mutant Zur proteins suggested an amino-terminal DNA contact domain around residue 65 and a dimerization and Zn(2+)-binding domain toward the carboxyl-terminal end.
Design and fabrication of high-temperature micro-hotplates for drop-coated gas sensors
2000-08-01

This paper reports on the optimisation of micromachined hotplates for gas-sensing applications designed to stand high-temperature coating processes and modes of operation. Different thin film materials, geometry and dimensions have been investigated regarding their power consumption, temperature distribution over the sensing area and robustness when annealed at high temperature. In comparison with oxide films, the micro-hotplates made of nitride were the most robust. They withstood annealing temperatures of up to 700°C and a pulsed temperature mode of operation. Their robustness allowed the sensing area to be heated up to a high temperature (550–700°C). These micro-hotplates are therefore suitable for the annealing “on-chip” of the gas-sensitive materials deposited in a drop-coating procedure. Sensors coated with a Pd-doped tin oxide drop and annealed using the integrated heater have been tested under different concentrations of CO and CH4 in air.
Transcriptional and translational regulation of heat shock proteins in leukocytes of endurance runners
2000-08-01

Heat shock proteins (HSP) represent cell-protective and antioxidant systems that may be induced by reactive oxygen species, cytokines, and hyperthermia. In the present study, we evaluated the influence of heavy endurance exercise and training on HSP27 and HSP70 in peripheral leukocytes of 12 athletes (before and at 0, 3, and 24 h after a half-marathon) and 12 untrained controls on protein and mRNA levels by flow cytometry and RT/PCR, respectively. HSP transcripts increased significantly immediately after acute exertion accompanied by elevated levels of corresponding proteins. HSP protein expression remained high until 24 h postexercise. Significant increases of plasma interleukin-8, myeloperoxidase, and creatine kinase occurred after exercise. Basal HSP expression was usually lower in trained compared with untrained subjects. Applying in vitro heat shock to resting blood samples of all subjects significantly stimulated HSP mRNA, showing higher increases in trained individuals. The exercise-induced alterations indicate that immunocompetent cells became activated. In addition to heat stress, other exercise-associated stress agents (oxidants, cytokines) may have also participated in stimulation of HSP expression in leukocytes. The expression pattern of HSP due to training status may be attributed to adaptive mechanisms.
Hopanoids are formed during transition from substrate to aerial hyphae inStreptomyces coelicolorA3(2)
2000-08-01

Streptomyces coelicolor A3(2) contains a cluster of putative isoprenoid and hopanoid biosynthetic genes. The strain does not produce the pentacyclic hopanoids in liquid culture but produces them on solid medium when sporulating. Mutants defective in the formation of aerial mycelium and spores (bld), with the exception of bldB, do not synthesize hopanoids, whereas mutants, which form aerial mycelium but no spores (whi), do. The membrane condensing hopanoids possibly may alleviate stress in aerial mycelium by diminishing water permeability across the membrane.
B cell epitopes of gliadin
2000-08-01

SUMMARY A phage displayed dodecapeptide library and synthetic octapeptides spanning the complete sequence of α- and γ-type gliadin and overlapping in six amino acids (pepscan) were screened for binding to human gliadin antibodies (AGA). Phage display experiments led to four sequences recognized with significantly higher frequency by sera with raised IgA-AGA titres than by control sera. All these peptides contained the core sequence PEQ. Pepscan experiments revealed binding of AGA to five prominent regions: (i) QXQPFP (binding to IgG and IgA, X representing P, Q, and L); (ii) IPEQ (IgG) and WQIPEQ (IgA); (iii) FFQP (IgG) and QGXFQP (IgA, X representing F and S); (iv) PQQLPQ (IgG and IgA), all in α-type gliadin; and (v) QPQQPF (IgG and IgA) in γ-type gliadin. In two of the sequences (QPQQPF and QQQPFP), substitution of Q by E resulting in QPEQPF and QEQPFP, respectively, increased significantly binding of AGA from sera of patients with biopsy-proven or suspected coeliac disease (CoD), all positive for endomysium antibodies (EmA). In contrast, binding of sera with high AGA titre from EmA-negative patients (CoD and dermatitis herpetiformis excluded) was not enhanced by this substitution. Thus, AGA directed against these modified epitopes can be regarded as specific for CoD. This is the first study demonstrating that deamidation of gliadin improves reactivity of AGA of CoD patients.
Glutathione metabolism and oxidative stress in neurodegeneration
2000-08-01

Oxidative stress occurs as a consequence of an alteration in the equilibrium of the production of reactive oxygen species and antioxidative processes in favor of the production of reactive oxygen species. Such compounds are continuously generated during oxidative metabolism. Compared to other organs the brain appears to be in an unfavorable position regarding the generation and the detoxification of reactive oxygen species. Evidence for the occurrence of oxidative stress in brain has been reported for aging and a variety of neurological and neurodegenerative diseases, indicating that under such conditions antioxidative processes, such as the glutathione system, might be insufficient. The following two minireviews summarize the current knowledge on the metabolism of the antioxidant glutathione in brain cells and the evidence for disturbances of the metabolism of this antioxidant under neuropathological conditions. Recent evidence for a metabolic cooperation between astrocytes and neurons in glutathione metabolism has enhanced the knowledge of the basal metabolism of this antioxidant in brain and suggests new strategies for potential prevention of neuronal loss during oxidative stress in brain.
Increase Characteristics of the Cumulated Excess-CO2 and the Lactate Concentration During Exercise
2000-08-01

The so-called excess-CO2 in physical exertion results stoichiometrically directly from the quantity of protons bound in bicarbonate buffering. This situation is used in determining the ventilatory threshold (VT). However, the extent to which the degree and increase characteristics of excess-CO2 can be used as an equivalent to blood lactate concentrations is uncertain. To investigate this relationship, 21 healthy men exercised on a cycle ergometer (starting at 50 watt, increases of 50 watt every 3 minutes) to subjective exhaustion. To evaluate the characteristics of this increase, a slope constant lambda was calculated in relation to performance for both the blood lactate concentration (lambda lactate) and the cumulated excess-CO2 (lambda CO2 excess). The start of the lactate increase (LT) and excess-CO2 (VT) showed good intercorrelation (VT=2.27+0.98 x LT; r=0.914; P<0.001). Mean lambda lactate and lambda CO2 excess were of similar dimensions in all subjects (69.3 +/- 39.8 watt vs. 80.11 +/- 15.7 watt), but a minority of the subjects (n=7) showed a considerably more gradual increase for the excess-CO2 to the maximum. Since in addition there was no significant correlation between the absolute values for maximum lactate concentrations and the cumulative excess-CO2, an interindividual prediction of lactate concentrations from the excess-CO2 would be difficult. It is an open question, however, whether perhaps additional performance-limiting factors, such as the ventilation or the buffering capacity, may be included when measuring the excess-CO2 so that this parameter could be more a measure for the formation rate of new lactate than the blood lactate concentration alone.