julilili42/papers huggingface dataset:
Keto–enol tautomerism in β‐ketoesters: CH3C(O)CHXC(O)OY (X = H, Cl; Y = CH3, C2H5). Vibrational analyses, NMR spectra and quantum chemical calculations
2001-04-26

Abstract The tautomeric equilibria of the β‐ketoesters [CH 3 C(O)CH 2 C(O)OCH 3 ( I ), CH 3 C(O)CHClC(O)OCH 3 ( II ), CH 3 C(O)CH 2 C(O)OCH 2 CH 3 ( III ) and CH 3 C(O)CHClC(O)OCH 2 CH 3 ( IV )] were studied by NMR spectroscopy and, in the case of I and II , by quantum chemical calculations ( ab initio and density functional methods). In addition, liquid‐state Fourier transform infrared and Raman spectra were analysed for all four compounds. They revealed the existence of two tautomers, diketo and enol forms. In the NMR spectra only signals for the diketo form could be observed for I and III . However, the calculations for I and II predicted the enol structures to be the most stable species. Copyright © 2001 John Wiley &amp; Sons, Ltd.
Seed dispersal in Palicourea rigida, a common treelet species from neotropical savannas
2001-04-27

The dispersal system of Palicourea rigida (Rubiaceae), a common woody species of neotropical savannas, was studied in a seasonal Venezuelan savanna. Production and consumption of fruits, dispersal agents, feeding behaviour, transport and effects on seed viability, were investigated by field observations, cage experiments and viability tests. To compare different dispersers, quantitative and qualitative dispersal parameters were calculated. About 59% of the fruit crop was dispersed successfully by birds. Although 10 different bird species consumed the fruits of Palicourea rigida , three bird species dispersed 79% of the fruits ( Tyrannus melancholicus , Molothrus bonariensis and Elaenia chiriquensis ). T. melancholicus (Tyrannidae) was the most important dispersal agent, with more than 39% of dispersed seeds. In contrast to the predictions of the specialization vs. generalization paradigm, this system achieves high effectiveness by means of predominantly unspecialized traits in both the plant and the dispersers. Se estudió el sistema de dispersión de Palicourea rigida (Rubiaceae), una leñosa común de las sabanas neotropicales, en una sabana estacional de Venezuela. Mediante observaciones de campo y experimentos en jaulas y en el laboratorio, se estudiaron paramétros tales como producción, transporte y consumo de frutos, los agentes dispersores y su comportamiento y los efectos sobre la viabilidad de las semillas. Para comparar los agentes de dispersión se estimaron paramétros cualitativos y cuantitativos. Cerca del 59% de la cosecha total de frutos fue dispersada existosamente por pájaros. Aunque los frutos fueron consumidos por diez especies de aves, el 79% de los frutos fueron dispersados por solamente tres especies ( Tyrannus melancholicus, Molothrus bonariensis y Elaenia chiriquensis ). T. melancholicus (Tyrannidae) fue el más importante agente dispersor con más del 39% del total de semillas dispersadas. En contraste con el paradigma de especialización vs. generalización, este sistema alcanza alta efectividad pero se caracteriza por rasgos poco especializados, tanto en la planta como en los dispersores.
Lack of Pericytes Leads to Endothelial Hyperplasia and Abnormal Vascular Morphogenesis
2001-04-30

The association of pericytes (PCs) to newly formed blood vessels has been suggested to regulate endothelial cell (EC) proliferation, survival, migration, differentiation, and vascular branching. Here, we addressed these issues using PDGF-B– and PDGF receptor-β (PDGFR-β)–deficient mice as in vivo models of brain angiogenesis in the absence of PCs. Quantitative morphological analysis showed that these mutants have normal microvessel density, length, and number of branch points. However, absence of PCs correlates with endothelial hyperplasia, increased capillary diameter, abnormal EC shape and ultrastructure, changed cellular distribution of certain junctional proteins, and morphological signs of increased transendothelial permeability. Brain endothelial hyperplasia was observed already at embryonic day (E) 11.5 and persisted throughout development. From E 13.5, vascular endothelial growth factor-A (VEGF-A) and other genes responsive to metabolic stress became upregulated, suggesting that the abnormal microvessel architecture has systemic metabolic consequences. VEGF-A upregulation correlated temporally with the occurrence of vascular abnormalities in the placenta and dilation of the heart. Thus, although PC deficiency appears to have direct effects on EC number before E 13.5, the subsequent increased VEGF-A levels may further abrogate microvessel architecture, promote vascular permeability, and contribute to formation of the edematous phenotype observed in late gestation PDGF-B and PDGFR-β knock out embryos.
Real Options Valuation of Highly Uncertain Investments: Are UMTS-Licenses Worth their Money?
2001-04-30

We adopt a real options approach to analyse the value of recently auctioned UMTS- licenses, focussing on Germany as the largest European market. For that purpose we develop a real options model with an abandonment as well as a growth option. Not having an appropriate underlying security of the options, we pursue an indirect approach by assuming a stochastic process for the number of mobile phone users. As we also take account of the optimal option exercise, we have to rely on numerical analysis rather than on closed form solutions. Our real options model enables us to value the flexibility inherent in the UMTS investments. On the basis of a sensitivity analysis it turns out that two variables are crucial for a positive expected value of the investments: the initial customer base of a mobile phone company as well as the realised net cash &amp;deg;ows per user.
Specific heat of the Kelvin modes in low temperature superfluid turbulence
2001-04-30

It is pointed out that the specific heat of helical vortex line excitations, in low temperature superfluid turbulence experiments carried out in helium II, can be of the same order as the specific heat of the phononic quasiparticles. The ratio of Kelvin mode and phonon specific heats scales with L_0 T^{-5/2}, where L_0 represents the smoothed line length per volume within the vortex tangle, such that the contribution of the vortex mode specific heat should be observable for L_0 = 10^6-10^8 cm^{-2}, and at temperatures which are of order 1-10 mK.
Key Role of Teichoic Acid Net Charge in Staphylococcus aureus Colonization of Artificial Surfaces
2001-05-01

ABSTRACT Staphylococcus aureus is responsible for a large percentage of infections associated with implanted biomedical devices. The molecular basis of primary adhesion to artificial surfaces is not yet understood. Here, we demonstrate that teichoic acids, highly charged cell wall polymers, play a key role in the first step of biofilm formation. An S. aureus mutant bearing a stronger negative surface charge due to the lack of d -alanine esters in its teichoic acids can no longer colonize polystyrene or glass. The mutation abrogates primary adhesion to plastic while production of the glucosamine-based polymer involved in later steps of biofilm formation is not affected. Our data suggest that repulsive electrostatic forces can lead to reduced staphylococcal biofilm formation, which could have considerable impact on the design of novel implanted materials.
Systematic Evolution of a DNA Aptamer Binding to Rat Brain Tumor Microvessels
2001-05-01

Tumor microvessels differ in structure and metabolic function from normal vasculature, and neoangiogenesis is associated with quantitative and qualitative changes in expression of endothelial proteins. Such molecules could serve as molecular addresses differentiating the tumor vasculature from those of the normal brain. We have applied Systematic Evolution of Ligands by EXponential enrichment (SELEX) against transformed endothelial cells as a complex target to select single-stranded DNA-ligands (aptamers) that function as histological markers to detect microvessels of rat experimental glioma, a fatal brain tumor that is highly vascularized. Both the SELEX selection procedure as well as subsequent deconvolution-SELEX were analyzed by fluorescence based methods (flow cytometry and fluorescence microscopy). Of 25 aptamers analyzed, one aptamer was selected that selectively bound microvessels of rat brain glioblastoma but not the vasculature of the normal rat brain including peritumoral areas. The molecular target protein of aptamer III.1 was isolated from endothelial cells by ligand-mediated magnetic DNA affinity purification. This protein was identified by mass spectrometry as rat homologue of mouse pigpen, a not widely known endothelial protein the expression of which parallels the transition from quiescent to angiogenic phenotypes in vitro. Because neoangiogenesis, the formation of new blood vessels, is a key feature of tumor development, the presented aptamer can be used as a probe to analyze pathological angiogenesis of glioblastoma. The presented data show that pigpen is highly expressed in tumor microvessels of experimental rat brain glioblastoma and may play an important role in warranting blood supply, thus growth of brain tumors.
Gain in Strength and Muscular Balance After Balance Training
2001-05-01

The isolated effect of balance training on muscle strength of the flexors and extensors of the knee, without accompanying strength training, has not been addressed in the past. Effects of a balance training program alone were compared to a strength training program. Balance and strength training were performed by 15 persons each for 6 weeks including 12 training units of 25 min. Balance training was performed on instability training devices such as rolling board, mini trampoline and large rubber ball. The 15 persons of the strength training group trained on machines for leg curls and on leg presses for 25 min per unit. Measurements for balance were performed with one-leg balance on a narrow edge and a tilting stabilometer for 30 s; maximum isometric strength was measured using an isokinetic device for each leg separately. The muscular balance between dominant and non-dominant leg was calculated. Strength gain was similar for the flexors and extensors in both groups. One-leg balance improved after balance training (P< 0.01) with a 100% increase over the strength training group (P < 0.05) and the stabilometer test for each person in the balance (P < 0.01), but not in the strength training group. In the balance group the initial difference between right and left diminished. The results indicate balance training to be effective for gain in muscular strength, and secondly, in contrast to strength training, equalisation of muscular imbalances may be achieved after balance training.
Changes of HSP72-expression in leukocytes are associated with adaptation to exercise under conditions of high environmental temperature
2001-05-01

Abstract Overexpression of the heat shock protein HSP72 providesthermotolerance. We asked if two consecutive endurance runs 1 weekapart (CR1, CR2) and additional environmental heat stress affectHSP72-expression in leukocytes of nonheat-acclimated enduranceathletes. Twelve subjects were allocated randomly into two groups. Group HH completed both runs at 28°C ambient temperature, and groupNH performed CR1 at 18°C and CR2 at 28°C. HSP72-expression wasdetermined by flow cytometry and RT-PCR before and 0, 24, and 48 hafter exercise. Additionally, post-exercise cells were exposed toin vitro heat shock (HS; 2 h, 42°C). The prolonged, high HSP72 protein level after CR1 in HH compared with NH may reflectthermotolerance induced by endurance exercise at high ambienttemperature. Adaptation of cardiocirculatory/thermoregulatory capacityafter CR2 in HH went along with a more rapid down-regulation of HSP72compared with CR1. HSP72 mRNA demonstrated temperature-related changesafter exercise. The reduced HS response in vitro after CR2may represent exercise-related adaptation mechanisms. HSP72concentrations in leukocytes may indicate previous exercise- andtemperature-related stress conditions and adaptation in immunocompetentcells.
Recent advances in capillary electrophoresis/electrospray-mass spectrometry
2001-05-01

In this review, the progress in hyphenation of capillary electrophoresis (CE) with electrospray ionization-mass spectrometry (ESI-MS) since the article of Banks (Banks, J. F., Electrophoresis 1997, 18, 2255-2266) is reported. In all capillary-based electromigration techniques, such as capillary gel electrophoresis (CGE), capillary isotachophoresis (CITP), capillary isoelectric focussing (CIEF), micellar electrokinetic chromatography (MEKC), affinity capillary electrophoresis (ACE), as well as in the hybrid techniques capillary electrochromatography (CEC), and pressurized capillary electrochromatography (pCEC) progress has been made in experimental setups, and for many groups of analytes, such as peptides, proteins, nucleotides, saccharides, drugs and their metabolites, CE/ESI-MS has been successfully applied. Electromigration is further miniaturized. New preconcentration methods allow the investigation of compounds, which are not sensitively detected with ESI-MS. Coordination ion spray (CIS) MS is another method for sensitivity enhancement by on-line formation of charged coordination compounds.
Pseudomonas aeruginosa mutations in lasI and rhlI quorum sensing systems result in milder chronic lung infection
2001-05-01

To understand the importance of quorum sensing in chronic Pseudomonas aeruginosa lung infection, the in vivo pathogenic effects of the wild-type P. aeruginosa PAO1 and its double mutant, PAO1 lasI rhlI, in which the signal-generating parts of the quorum sensing systems are defective were compared. The rat model of P. aeruginosa lung infection was used in the present study. The rats were killed on days 3, 7, 14 and 28 after infection with the P. aeruginosa strains. The results showed that during the early stages of infection, the PAO1 double mutant induced a stronger serum antibody response, higher production of pulmonary interferon gamma, and more powerful blood polymorphonuclear leukocyte (PMN) chemiluminescence compared to its wild-type counterpart. On days 14 and 28 post-infection, significantly milder lung pathology, a reduction in the number of mast cells present in the lung foci, a reduced number of lung bacteria, and minor serum IgG and IgG1 responses but increased lung interferon gamma production were detected in the group infected with the PAO1 double mutant when compared with the PAO1-infected group. Delayed immune responses were observed in the PAO1-infected group and they might be associated with the production of virulence factors that are controlled by the quorum sensing systems. The conclusion of this study is that functional lasI and rhlI genes of P. aeruginosa PAO1 play a significant role during lung infection.
Signal-regulatory protein α (SIRPα) but not SIRPβ is involved in T-cell activation, binds to CD47 with high affinity, and is expressed on immature CD34+CD38−hematopoietic cells
2001-05-01

Abstract Signal-regulatory proteins (SIRPs) represent a new family of inhibitory/activating receptor pairs. They consist of 3 highly homologous immunoglobulin (Ig)–like domains in their extracellular regions, but differ in their cytoplasmic regions by the presence (SIRPα) or absence (SIRPβ) of immunoreceptor tyrosine-based inhibitory motifs (ITIMs). To analyze the differential expression on hematopoietic cells, function and ligand binding capacity of SIRPα and SIRPβ molecules, soluble fusion proteins consisting of the extracellular domains of SIRPα1, SIRPα2, and SIRPβ1, as well as SIRPα/β-specific and SIRPβ-specific monoclonal antibodies (MoAbs) were generated. In contrast to SIRPα1 and SIRPα2, no adhesion of SIRPβ1 to CD47 could be detected by cell attachment assays and flow cytometry. Using deletion constructs of SIRPα1, the epitope responsible for SIRPα1 binding to CD47 could be confined to the N-terminal Ig-like loop. Flow cytometry analysis with SIRPα/β- and SIRPβ-specific MoAbs revealed that SIRPα but not SIRPβ is expressed on CD34+CD38− hematopoietic cells. In addition, a strong SIRPα expression was also observed on primary myeloid dendritic cells (DCs) from peripheral blood as well as on in vitro generated DCs. Analysis of the T-cell stimulatory capacity of in vitro generated DCs in the presence of soluble SIRPα1 fusion proteins as well as SIRPα/β-specific and CD47-specific MoAbs revealed a significant reduction of T-cell proliferation in mixed lymphocyte reaction and inhibition of induction of primary T-cell responses under these conditions. In contrast, soluble SIRPα or SIRPβ-specific antibodies had no effect. The data suggest that the interaction of SIRPα with CD47 plays an important role during T-cell activation and induction of antigen-specific cytotoxic T-lymphocyte responses by DCs.
Sporadic cerebellar ataxia associated with gluten sensitivity
2001-05-01

A total of 104 patients with sporadic cerebellar ataxia were tested for antigliadin and antiendomysium antibodies. Twelve individuals (11.5%) with gluten sensitivity underwent duodenal biopsy and extensive clinical, electrophysiological, neuropsychological, radiological and laboratory investigations including human leucocyte antigen (HLA) typing. Two patients showed typical changes of gluten-sensitive enteropathy with crypt hyperplasia and mucosal flattening. In five patients, the intraepithelial lymphocyte count was elevated. Sporadic ataxia with gluten sensitivity was found to be tightly linked to the HLA DQB1*0201 haplotype (70%). Neurological symptoms were not related to hypovitaminosis or inflammatory CSF changes. The clinical syndrome was dominated by progressive cerebellar ataxia with ataxia of stance and gait (100%), dysarthria (100%) and limb ataxia (97%). Oculomotor abnormalities were gaze-evoked nystagmus (66.7%), spontaneous nystagmus (33.3%), saccade slowing (25%) and upward gaze palsy (16.7%). Extracerebellar features also included deep sensory loss (58.3%), bladder dysfunction (33.3%) and reduced ankle reflexes (33.3%). In accordance with clinical findings, electrophysiological investigations revealed prominent axonal neuropathy with reduced amplitudes (50%) and abnormal evoked potentials (58.3%). On neuropsychological testing, patients presented with moderate verbal memory and executive dysfunction. All patients had evidence of cerebellar atrophy on MRI. We conclude that sporadic ataxia may be associated with positive antibodies against gliadin. Nevertheless, mucosal pathology does not represent an obligatory condition of ataxia with gluten sensitivity. The fact that the disease is strongly associated with the same HLA haplotypes found in coeliac disease not only demonstrates coeliac disease and ataxia with gluten sensitivity to be part of the same disease entity but supports the hypothesis of an immunological pathogenesis of cerebellar degeneration.
A New Rapid Immunohistochemical Staining Technique Using the EnVision Antibody Complex
2001-05-01

Rapid immunohistochemical investigation, in addition to staining with hematoxylin and eosin, would be useful during intraoperative frozen section diagnosis in some cases. This study was undertaken to investigate whether the recently described EnVision system, a highly sensitive two-step immunohistochemical technique, could be modified for rapid immunostaining of frozen sections. Forty-five primary antibodies were tested on frozen sections from various different tissues. After fixation in acetone for 1 min and air-drying, the sections were incubated for 3 min each with the primary antibody, the EnVision complex (a large number of secondary antibodies and horseradish peroxidase coupled to a dextran backbone), and the chromogen (3,3′diaminobenzidine or 3-amino-9-ethylcarbazole). All reactions were carried out at 37C. Specific staining was seen with 38 antibodies (including HMB-45 and antibodies against keratin, vimentin, leukocyte common antigen, smooth muscle actin, synaptophysin, CD34, CD3, CD20, and prostate-specific antigen). A modification of the EnVision method allows the detection of a broad spectrum of antigens in frozen sections in less than 13 min. This method could be a useful new tool in frozen section diagnosis and research. (J Histochem Cytochem 49:623–630, 2001)
Proton MR spectroscopy with metabolite-nulling reveals elevated macromolecules in acute multiple sclerosis
2001-05-01

Proton magnetic resonance spectroscopy has shown elevated signals in the spectral region of lipids in acute multiple sclerosis lesions. The metabolite-nulling technique allows the separation of macromolecules from other metabolites, such as lactate, N-acetyl-aspartate, creatine, choline and myo-inositol. Using this technique in studies on multiple sclerosis patients, we were able to differentiate macromolecules biochemically in acute and chronic multiple sclerosis lesions. Ten patients with acute, contrast-enhancing multiple sclerosis lesions, 10 patients with chronic lesions and 10 healthy control subjects were investigated with a 1.5 T whole body system, using a stimulated echo acquisition mode (STEAM) sequence with metabolite-nulling and outer volume saturation. Metabolites and macromolecules were quantitated absolutely. The 0.9 and 1.3 parts per million (p.p.m.) resonances of the macromolecules were significantly elevated in acute lesions compared with chronic lesions and healthy controls (P < 0.001 for 0.9 p.p.m., P < 0.05 for 1.3 p.p.m.). The macromolecular resonances at 2.1 and 3.0 p.p.m. in acute and chronic lesions were normal. N-acetyl-aspartate was significantly reduced in acute and chronic lesions compared with controls (P < 0.05 and P < 0.01, respectively). Choline was significantly elevated in acute lesions compared with controls (P < 0.05). Up to now, elevated resonances at 0.9 and 1.3 p.p.m. in acute lesions have been interpreted as lipids. In metabolite-nulled spectra, the macromolecular resonances did not fit those of lipids and might have been due to proteins or polypeptides containing the amino acids alanine, threonine, valine, leucine and isoleucine. These account for approximately 40% of the amino acids of myelin proteolipid protein and for approximately 20% of myelin basic protein. The increased macromolecular resonances at 0.9 and 1.3 p.p.m. may be interpreted as biochemical markers of myelin fragments and may be used as reliable markers of acute multiple sclerosis lesions as they provide clear discrimination among acute and chronic lesions and controls.
Fetal Alcohol Syndrome: An International Perspective
2001-05-01

This article represents the proceedings of a workshop at the 2000 ISBRA Meeting in Yokohama, Japan. The chairs were Kenneth R. Warren and Faye J. Calhoun. The presentations were (1) Epidemiological research on fetal alcohol syndrome (FAS) in the United States, by Philip A. May; (2) An overview of fetal alcohol syndrome in the Western Cape Province of South Africa, by Denis L. Viljoen and Ting‐Kai Li; (3) Diagnostic perspectives of fetal alcohol and tobacco syndromes, by Harumi Tanaka; (4) FAS among pupils of special boarding schools and orphanages in Moscow, Russia, by Galina S. Marinicheva and Luther K. Robinson; and (5) Research on FAS and FAE in Germany: Update and perspectives, by Goetz Mundle.
Neuroimaging in Alcoholism: Ethanol and Brain Damage
2001-05-01

This article represents the proceedings of a symposium at the 2000 ISBRA Meeting in Yokohama, Japan. The co-chairs were Karl Mann and Ingrid Agartz. The presentations were (1) Neuropathological changes in alcohol-related brain damage, by Clive Harper; (2) Regional brain volumes including the hippocampus and monoamine metabolites in alcohol dependence, by Ingrid Agartz, Susan Shoaf, Robert R, Rawlings, Reza Momenan, and Daniel W Hommer; (3) Diffusion tensor abnormalities in imaging of white matter alcoholism, by Adolf Pfefferbaum and Edith V. Sullivan; (4) Use of functional MRI to evaluate brain activity during alcohol cue exposure in alcoholics: Relationship to craving, by Raymond F. Anton, David J. Drobes, and Mark S. George; and (5) mu-Opiate receptor availability in alcoholism: First results from a positron emission tomography study, by Karl Mann, Roland Bares, Hans-Juergen Machulla, Goetz Mundle, Matthias Reimold, and Andreas Heinz.