julilili42/papers huggingface dataset:
Role of Radiotherapy in the Treatment of Supratentorial Primitive Neuroectodermal Tumors in Childhood: Results of the Prospective German Brain Tumor Trials HIT 88/89 and 91
2002-02-01

PURPOSE: To evaluate the outcome of children with supratentorial primitive neuroectodermal tumors after surgery, irradiation, and chemotherapy and to identify factors predictive for survival. PATIENTS AND METHODS: Sixty-three children in the prospective trials HIT 88/89 and HIT 91 were eligible. Complete resection was performed in 21 patients. Patients were randomized for preirradiation chemotherapy, consisting of two cycles of ifosfamide, etoposide, methotrexate, cisplatin, and cytarabine (n = 40), or chemotherapy after irradiation, consisting of eight cycles with cisplatin, vincristine, and lomustine (n = 23). Irradiation volume was recommended to encompass the neuraxis with 35.2-Gy total dose followed by a boost (20.0 Gy) to the primary tumor site (n = 54). Seven patients were irradiated to the tumor region only with a total dose of 54.0 Gy. RESULTS: Overall survival at 3 years was 48.4%. Progression occurred in 38 children, with local recurrences in 27 patients. The only significant prognostic factor was dose and volume of radiotherapy (progression-free survival after 3 years was 49.3% with correct treatment compared with 6.7% for 15 children with major violations of radiotherapy). Ten early progressions occurred during adjuvant therapy (eight before and two during radiotherapy), nine of them treated with preirradiation chemotherapy. There was a positive trend in outcome for nonmetastatic and pineal tumors. CONCLUSION: Significant predictive factors were dose and volume of radiotherapy. Volume of irradiation should encompass the whole CNS with additional boost to the tumor region. Local doses of at least 54 Gy and a craniospinal dose of 35 Gy are necessary. Preirradiation chemotherapy seems to increase risk of early progression.
New Inorganic-Organic Hybrid Materials for HPLC Separation Obtained by Direct Synthesis in the Presence of a Surfactant
2002-02-01

Nanostructured, mesoporous inorganic–organic hybrid xerogels were reproducibly synthesized by a sol–gel procedure. For the introduction of long alkyl chains into inorganic polymers, trifunctional n-alkyltrialkoxysilanes of the type CH3(CH2)nSi(OR)3 (n = 7, 11, 17; R = CH3, C2H5) were co-condensed with Si(OEt)4 (TEOS). The synthetic pathway involves the employment of n-hexadecylamine as template and catalyst. The xerogels obtained by the present procedure consist of uniform spherical particles with a diameter of about 1 μm. The composition of the new materials was determined by 13C and 29Si cross polarization magic angle spinning (CP/MAS) NMR spectroscopy. In addition, the degree of organization was investigated by small angle X-ray and electron diffraction. In accordance with 13C CP/MAS NMR spectroscopic measurements, the alkyl chains form a crystalline arrangement within the silica polymer. Brunauer–Emmett–Teller (BET) adsorption measurements confirm specific surface areas of up to 1400 m2/g. The material properties prove the xerogels to be suitable as stationary phases in high-performance liquid chromatography (HPLC). These novel mesoporous, nanostructured materials have been successfully employed in HPLC for the first time. Different standard reference materials (SRMs) containing polycyclic aromatic hydrocarbons have been separated with the xerogels described in the present work.
A Helical Region in the C Terminus of Small-conductance Ca2+-activated K+ Channels Controls Assembly with Apo-calmodulin
2002-02-01

Small conductance Ca(2+)-activated potassium (SK) channels underlie the afterhyperpolarization that follows the action potential in many types of central neurons. SK channels are voltage-independent and gated solely by intracellular Ca(2+) in the submicromolar range. This high affinity for Ca(2+) results from Ca(2+)-independent association of the SK alpha-subunit with calmodulin (CaM), a property unique among the large family of potassium channels. Here we report the solution structure of the calmodulin binding domain (CaMBD, residues 396-487 in rat SK2) of SK channels using NMR spectroscopy. The CaMBD exhibits a helical region between residues 423-437, whereas the rest of the molecule lacks stable overall folding. Disruption of the helical domain abolishes constitutive association of CaMBD with Ca(2+)-free CaM, and results in SK channels that are no longer gated by Ca(2+). The results show that the Ca(2+)-independent CaM-CaMBD interaction, which is crucial for channel function, is at least in part determined by a region different in sequence and structure from other CaM-interacting proteins.
Mitomycin C in combination with radiotherapy as a potent inhibitor of tumour cell repopulation in a human squamous cell carcinoma
2002-02-01

The potential of Mitomycin C in combination with fractionated irradiation to inhibit tumour cell repopulation of a fast growing squamous cell carcinoma after fractionated radiotherapy was investigated in vivo. A rapidly growing human squamous cell carcinoma (FaDu(dd)) was used for the study. For experiments, NMRI (nu/nu) mice with subcutaneously growing tumours were randomly allocated to no treatment, Mitomycin C, fractionated irradiation (ambient: 11 x 4.5 Gy in 15 days), or fractionated irradiation combined with Mitomycin C. Graded top up doses (clamped blood flow: 0-57 Gy) were given at day 16, 23, 30 or 37. End point of the study was the time to local tumour progression. Data were examined by multiple regression analysis (Cox). Mitomycin C alone resulted in a median time to local tumour progression of 23 (95% confidence limits: 17-43) days, fractionated irradiation in 31 (25-35) days and combined Mitomycin C plus fractionated irradiation in 65 (58-73) days (P=0.02). Mitomycin C decreased the relative risk of local recurrence by 94% (P<<0.001) equivalent to 31.7 Gy top up dose. Repopulation accounted for 1.33 (0.95-1.72) Gy per day top up dose after fractionated irradiation alone and for 0.68 (0.13-1.22) Gy per day after fractionated irradiation+Mitomycin C (P=0.018). Mitomycin C significantly reduces the risk of local recurrence and inhibits tumour cell repopulation in combination with fractionated irradiation in vivo in the tested tumour model.
Dynamics of Gamma-band Activity Induced by Auditory Pattern Changes in Humans
2002-02-01

Increasing evidence suggests separate auditory pattern and space processing streams. The present paper describes two magnetoencephalogram studies examining gamma-band activity to changes in auditory patterns using consonant-vowel syllables (experiment 1), animal vocalizations and artificial noises (experiment 2). Two samples of each sound type were presented to passively listening subjects in separate oddball paradigms with 80% standards and 20% deviants differing in their spectral composition. Evoked magnetic mismatch fields peaking approximately 190 ms poststimulus showed a trend for a left-hemisphere advantage for syllables, but no hemispheric differences for the other sounds. Frequency analysis and statistical probability mapping of the differences between deviants and standards revealed increased gamma-band activity above 60 Hz over left anterior temporal/ventrolateral prefrontal cortex for all three types of stimuli. This activity peaked simultaneously with the mismatch responses for animal sounds (180 ms) but was delayed for noises (260 ms) and syllables (320 ms). Our results support the hypothesized role of anterior temporal/ventral prefrontal regions in the processing of auditory pattern change. They extend earlier findings of gamma-band activity over posterior parieto-temporal cortex during auditory spatial processing that supported the putative auditory dorsal stream. Furthermore, earlier gamma-band responses to animal vocalizations may suggest faster processing of fear-relevant information.
The P2X7 receptor from Xenopus laevis: formation of a large pore in Xenopus oocytes
2002-02-01

The purinergic P2X 7 receptor is an ATP‐receptor channel predominantly expressed in immune cells. P2X 7 has been cloned from human, rat and mouse. Here we report cloning of the Xenopus laevis P2X 7 receptor (xP2X 7 ). xP2X 7 is only about 50% identical to the mammalian homologues, shows a broad tissue expression pattern, and has the electrophysiological characteristics typical of a P2X 7 receptor: low agonist affinity (EC 50 about 2.6 mM) and a non‐desensitizing current. Moreover, expression of xP2X 7 in Xenopus oocytes is sufficient to induce the formation of a large pore, which is permeable to large cations such as NMDG + . Identification of a non‐mammalian P2X 7 receptor may help to identify functionally important parts of the protein.
Clinical Characterization of Insulin Secretion as the Basis for Genetic Analyses
2002-02-01

A strong genetic component of the β-cell defect of type 2 diabetes is undisputed. We recently developed a modification of the classic hyperglycemic clamp to assess β-cell function in response to various stimuli (10 mmol/l glucose, additional glucagon-like peptide [GLP]-1, and arginine). Subjects at risk for developing type 2 diabetes (impaired glucose-tolerant individuals, women with gestational diabetes, and individuals with a family history of type 2 diabetes) clearly showed a significantly decreased mean secretory response to all secretagogues compared with controls. We also showed that normal glucose-tolerant carriers of the Gly972Arg polymorphism in the insulin receptor substrate 1 have significantly reduced insulin secretion in response to glucose and arginine but not to GLP-1. More remarkably, however, the relative impairment of the different secretory phases varied greatly in the same individual, indicating a substantial heterogeneity of β-cell dysfunction. Specific prominence of this heterogeneity may reflect a specific cellular defect of the β-cell. In subjects sharing this pattern of heterogeneity, any underlying genetic variant may be enriched and thus more likely not only to be identified but also to be related to a pathophysiological mechanism. In conclusion, we believe that careful clinical characterization of β-cell function (and dysfunction) is one way of identifying and understanding the genetic factors leading to the insulin secretory failure of type 2 diabetes.
Two New Triterpenes from Fern Adiantum incisum
2002-02-01

Two new triterpenes, adininaneone (1) and adininaonol (2) were isolated from Adiantum incisum. Three known triterpenes, adiantone (3), isoadiantone (4) and 23-hydroxyfernene (5) were also isolated for the first time from the methanolic extracts of A. insicum. The structures were elucidated with the help of modern spectroscopic techniques.
Conformationally constrained human calcitonin (hCt) analogues reveal a critical role of sequence 17–21 for the oligomerization state and bioactivity of hCt
2002-02-01

Calcitonin (Ct) is a 32‐residue peptide hormone that is mainly known for its hypocalcemic effect and the inhibition of bone resorption. Our previous studies have led to potent, side‐chain lactam‐bridged human Ct (hCt) analogues [Kapurniotu, A. Kayed, R., Taylor, J.W. &amp; Voelter W. (1999) Eur. J. Biochem. 265 , 606–618; Kapurniotu, A. &amp; Taylor, J.W. (1995) J. Med. Chem. 38 , 836–847]. We have hypothesized that a possibly type I β turn/β sheet conformation in the region 17–21 may play an important role in hCt bioactivity. To investigate this hypothesis, analogues of the potent hCt agonist cyclo17,21‐[Asp17,Lys21]hCt ( 1 ) bearing type I (and II′) or II β turn‐promoting substituents at positions 18 and 19 were designed, synthesized and their solution conformations, human Ct receptor binding affinities and in vivo hypocalcemic potencies were assessed. The novel analogues include cyclo17,21‐[Asp17, d ‐Phe19, Lys21]hCt ( 2 ), cyclo17,21‐[Asp17,Aib18,Lys21]hCt ( 3 ), cyclo17,21‐[Asp17, d ‐Lys18,Lys21]hCt ( 4 ), corresponding partial sequence peptides containing the lactam‐bridged region 16–22, and nonbridged control peptides. Only 1 showed a higher Ct receptor binding affinity than hCt, whereas analogues 2–4 had similar receptor affinities to hCt. In the in vivo hypocalcemic assay, 3 and 4 were as potent as 1 , whereas 2 completely lost the high potency of 1 , suggesting that type I (and II′) β turn‐promoting substituents are fully compatible with in vivo bioactivity. CD spectroscopy showed that analogues 1 – 4 were markedly β sheet‐stabilized compared to hCt and indicated the presence of distinct β turn conformeric populations in each of the analogues. Unexpectedly, the d ‐amino acid‐ or Aib‐containing cyclic analogues 2 – 4 but not 1 or hCt self‐associated into SDS denaturation‐stable dimers. Our results demonstrate a crucial role of the conformational and topological features of the residues in sequence 17–21 and in particular of residues 18 and 19 for human Ct receptor binding and in vivo bioactivity and also for the self association state of hCt. These results may assist to delineate the structure‐function relationships of hCt and to design novel hCt agonists for the treatment of osteoporosis and other bone‐disorder‐related diseases.
CENTER VORTICES IN CONTINUUM YANG-MILLS THEORY
2002-02-01

The properties of center vortices are discussed within continuum Yang-Mills theory. By starting from the lattice theory and carefully performing the continuum limit the gauge potential of center vortices is obtained and the continuum analog of the maximal center gauge fixing is extracted. It is shown, that the Pontryagin index of center vortices is given by their self-intersection number, which vanishes unless the center vortices host magnetic monpoles, which make the vortex sheets non-oriented. 1
Effects of water on cortical excitability in humans
2002-02-01

Abstract The effects of water on cortical excitability, measured using magnetoencephalographic recordings, were investigated in a sample of 19 healthy volunteers in a double‐blind, placebo experiment comparing water with saline solution. Spontaneous magnetoencephalogram as well as auditory‐evoked magnetic fields were recorded before and after the drinking of 750 mL water (9 subjects) or saline solution (10 subjects) and during and after hyperventilation following the drinking conditions. Hyperventilation was used to enhance the hypothesized synchronizing effect of water on spontaneous magnetoencephalographic activity. In addition, the magnetic fields were measured during a dichotic listening task under attended and unattended conditions. The prediction, that intake of water, because of induced cell swelling, will increase neuronal excitability and lead to an increased synchronization of the spontaneous magnetoencephalogram during hyperventilation was confirmed. Hyperventilation induced an increase of spectral power in all frequency bands particularly theta and delta power after water drinking. Furthermore, there was an increase of magnetic mismatch negativity (MMNm) amplitude in attended conditions and a simultaneous decrease in unattended conditions after water drinking. N1m (magnetic N1 wave) revealed significant changes during experimental conditions: increase after drinking and decrease after hyperventilation in both groups. MMNm for attended conditions showed a high positive correlation with osmolality changes (difference in the mol solute per kg water before and after drinking); N1m and PNm (magnetic processing negativity) as well as MMNm for unattended conditions showed significant correlations with subjective ratings of thirst and mood state.
Pleurovularia, a new genus of hyphomycetes proposed for a parasite on leaves of Microstegium sp. (Poaceae)
2002-02-01

The hyphomycete Ovularia polliniae, formerly excluded from Ramularia and allied genera and tentatively considered as related to Beniowskia sphaeroidea, was recently collected on leaves of the grass Microstegium sp. in Taiwan. Based on studies with light and transmission electron microscopy, O. polliniae was redescribed. Using type specimens, the taxonomic status of both fungal species was reevaluated. In O. polliniae, the conidiophores emerge directly through the outer cell wall of the host epidermis. They are either sparsely branched at the base or simple and composed of verruculose intercalary and terminal conidiogenous cells that produce conidia through minute, slightly darkened scars. The conidia are solitary, one-celled, obovoid, hyaline, smooth, and often have a large vacuole. By the combination of these characteristics, this fungus differs from similar species of Beniowskia, Ramularia, and Ramulariopsis. The new genus Pleurovularia and the new combination Pleurovularia polliniae are proposed to accommodate this parasite on Microstegium.
Liegen in Imidazolium-Tetrafluoroboraten Wasserstoffbrückenbindungen vor? Die Struktur von 1,3-Diisopropyl-4,5-dimethylimidazolium- Tetrafluoroborat [1] / Is Hydrogen Bonding Present in Imidazolium Tetrafluoroborates? The Structure of 1,3-Diisopropyl-4,5-dimethylimidazolium Tetrafluoroborate [1]
2002-02-01

1,3-Diisopropyl-4,5-dimethylimidazolium tetrafluoroborate (2) is obtained from 2,3-dihydro-1,3- diisopropyl-4,5-dimethylimidazol-2-ylidene (1) and HBF 4 • Et 2 O; the X-ray structure of 2 is reported.
Interactive visualization of volumetric vector fields using texture based particles
2002-02-01

This paper introduces a new approach to the visualization of volumetric vector fields with an adaptive distribution of animated particles that show properties of the underlying steady flow. The shape of the particles illustrates the direction of the vector field in a natural way. The particles are transported along streamlines and their velocity reflects the local magnitude of the vector field. Further physical quantities of the underlying flow can be mapped to the emissive color, the transparency and the length of the particles. A major effort has been made to achieve interactive frame rates for the animation of a large number of particles while minimizing the error of the computed streamlines. There are three main advantages of the new method. Firstly, the animation of the particles diminishes the inherent occlusion problem of volumetric vector field visualization, as the human eye can trace an animated particle even if it is highly occluded. The second advantage is the variable resolution of the visualization method. More particles are distributed in regions of interest. We present a method to automatically adjust the resolution to features of the vector field. Finally, our method is scalable to the computational and rasterization power of the visualization system by simply adjusting the number of visualized particles.
What the Infrared Behavior of QCD Green Functions can tell us about Confinement in the Covariant Gauge
2002-02-01

We review aspects of confinement in the covariant and local description of QCD and discuss to what extend our present knowledge of the infrared behavior of QCD Green functions can support this description.In particular, we emphasize: the positivity violations of transverse gluon and quark states, the Kugo-Ojima confinement criterion, and the conditions necessary to avoid the decomposition property for colored clusters.We summarize how these issues relate to the infrared behavior of the propagators in Landau gauge QCD as extracted from solutions to truncated Dyson-Schwinger equations and lattice simulations.
Mimicking the brain
2002-02-01

THE HUMAN brain looks unremarkable – it has the colour and consistency of cream cheese. From its appearance alone, one might assume that it fulfils some lowly role in the body. However, this grapefruit-sized organ can process information faster than any known computer. What is even more remarkable to physicists is the fact that this prodigiously powerful computing device has developed through biological evolution, with all of its apparent uncertainties and redundancies.
Effect of Cu/Zn-Superoxide Dismutase from the Fungal Strain Humicola lutea 103 on Antioxidant Defense of Graffi Tumor-Bearing Hamsters
2002-02-01

A novel Cu/Zn-containing superoxide dismutase (SOD) was isolated from the fungal strain Humicola lutea 103. Previously, a protective effect of this enzyme (HLSOD) against tumor growth and also superoxide production in Graffi tumor-bearing hamsters (TBH) were established. The aim of the present study was to investigate the effect of HLSOD on the activity of endogenous SOD and catalase in the cells from TBH during tumor progression. Our results point out that transplantation of Graffi tumor causes a significant decrease in SOD activity in the cells from liver of the hosts (from 35 to 59% compared to the control). In the tumor cells relatively low levels of SOD (about 7 U mg protein -1 ) were found, and Cu/ZnSOD was the main isoenzyme in total SOD activity. Tumor growth resulted in a reduction of catalase activity, which correlated with the process of tumor progression. A single dose (65 U) treatment with HLSOD caused an increase in endogenous SOD and catalase activity in healthy animals and resulted in restoration of the antioxidant ability in liver cells of the hosts at the early stage of tumor progression. The results show the possible participation of HLSOD in the host oxidant-antioxidant balance, which is probably one of the factors of its immunoprotective action established earlier.
NN correlations in a multinucleon system
2002-02-01

Cross sections for processes involving three or more identical nucleons in the final state are expected to be strongly suppressed near the threshold because of the Pauli exclusion principle. It is shown that the Migdal-Watson effect (final-state interaction between nucleons) removes this suppression.
On a Variation in the Economic Performance of Migrants by their Home Country’s Wage
2002-02-01

Although the economic performance of migrants in the receiving country undoubtedly depends on qualifications, it is also affected by inclinations. Given the probability of return migration, a behavioural link is established between the incentive of migrants to save in their country of destination and the prevailing wage rate in their home country. It is shown that migrants coming from a low‐wage country optimally save more than migrants from a high‐wage country. Policy and research implications suggested by this savings behaviour are alluded to.
The gluon condensate from gauge invariant vortex vacuum texture
2002-02-01

In SU (2) lattice gauge theory, a new self-restricted cooling procedure is developed to uncover the gauge invariant vortex vacuum texture.The emerging vortex vacuum structure amounts to the full string tension and gives rise to a mass dimension four condensate which is of pure vortex origin.
RECENT RESULTS IN THE CENTER VORTEX MODEL FOR THE INFRARED SECTOR OF YANG-MILLS THEORY
2002-02-01

A model for the infrared sector of SU (2) Yang-Mills theory, based on magnetic vortices represented by (closed) random surfaces, is presented.The model quantitatively describes both confinement and the topological aspects of Yang-Mills theory.Details (including an adequate list of references) can be found in the eprints hep-lat/9912003 and hep-lat/0004013, both to appear in Nucl.Phys.B.
Learning Recurrent Neural Models with Minimal Complexity from Neural Tuning Data
2002-02-01

We present a method for the estimation of nonlinear recurrent neural models from neural tuning data. Our algorithm makes no specific assumptions about the structure of the recurrent neural network model, except for the smoothness of the lateral interaction profile and feed-forward input kernel. A new learning algorithm is devised that achieves optimal generalization from small amounts of neural data that combines support vector regression with stability constraints resulting from the recurrent network dynamics, resulting in a semi-definite programming problem. The method is illustrated by fitting models for orientation tuning in the visual cortex.