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Selected AbstractsLimited conformational change of ,-lactoglobulin when adsorbed at the air,water interfaceBIOPOLYMERS, Issue 4-5 2002Marcel B. J. Meinders Abstract Detailed insight can be obtained from proteins at and near the air,water interface using external reflection IR and circular dichroism techniques. Besides information on local protein concentrations and surface layer thickness, it is shown that ,-lactoglobulin displays a limited unfolding at the interface. The conformational change is comparable to that observed upon heat-induced aggregation of the protein and can be understood in view of the high surface concentration of the protein (,40% volume fraction). The layer thickness and the conformational properties of the protein do not depend on the bulk concentration. After adsorption of ,-lactoglobulin to a preformed lipid monomolecular layer a similar conformational change is induced, suggesting that the folding properties of the protein itself determine the extent of conformational changes at the interfaces. © 2002 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 67: 319,322,2002 [source] Granzyme A expression reveals distinct cytolytic CTL subsets following influenza A virus infectionEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 5 2009Jessica M. Moffat Abstract CTL mediate anti-viral immunity via targeted exocytosis of cytolytic granules containing perforin and members of the granzyme (grz) serine protease family. Here, we provide the first analysis of grzA protein expression by murine anti-viral CTL. During the progression of influenza A virus infection, CTL expressed two divergent cytolytic phenotypes: grzA,B+ and grzA+B+. CTL lacked grzA expression during the initial rounds of antigen-driven division. High levels of grzA were expressed by influenza-specific CTL early post infection (day 6), particularly in tissues associated with the infected respiratory tract (bronchoalveolar lavage, lung). Following resolution of influenza infection, a small population of memory CTL expressed grzA. Interestingly, individual influenza A virus-derived epitope-specific CTL expressed different levels of grzA. The grzA expression hierarchy was determined to be KbPB1703=DbF262=KbNS2114>DbNP366=DbPA224 and inversely correlated with CTL magnitude. Therefore following influenza infection, a CTL cytolytic hierarchy was established relating to the different profiles of antigen expression and relative immunodominance. Analysis of CTL grzA expression during influenza virus immunity has enabled a more detailed insight into the cytolytic mechanisms of virus elimination. [source] Mapping the functional domain of the prion proteinFEBS JOURNAL, Issue 16 2003Taian Cui Prion diseases such as Creutzfeldt,Jakob disease are possibly caused by the conversion of a normal cellular glycoprotein, the prion protein (PrPc) into an abnormal isoform (PrPSc). The process that causes this conversion is unknown, but to understand it requires a detailed insight into the normal activity of PrPc. It has become accepted from results of numerous studies that PrPc is a Cu-binding protein and that its normal function requires Cu. Further work has suggested that PrPc is an antioxidant with an activity like that of a superoxide dismutase. We have shown in this investigation that this activity is optimal for the whole protein and that deletion of parts of the protein reduce or abolish this activity. The protein therefore contains an active domain requiring certain regions such as the Cu-binding octameric repeat region and the hydrophobic core. These regions show high evolutionary conservation fitting with the idea that they are important to the active domain of the protein. [source] Enantioselective Alcoholysis of meso -Glutaric Anhydrides Catalyzed by Cinchona -Based Sulfonamide CatalystsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2010Sang Eun Park Abstract The bifunctional Cinchona -based sulfonamide catalysts showed the highest levels of enantioselectivity reported to date in the alcoholytic desymmetrization of meso -glutaric anhydrides. Density functional theory (DFT) computational studies provide detailed insight into the observed sense of enantioselectivity. Moreover, detailed experimental studies and single crystal X-ray analysis confirmed that these bifunctional organocatalysts 3 do not form H-bonded self-aggregates in both solution and solid state. The synthetic utility of this methodology was also demonstrated in the synthesis of pharmaceutically important ,-amino acids, such as (S)-pregabalin. Of the many asymmetric syntheses of enantiomerically pure (S)-pregabalin reported to date, our synthesis requires the least number of and the simplest steps. [source] Tautomeric forms of adenine: Vertical ionization energies and Dyson orbitalsINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 10 2010Raman K. Singh Abstract For the MP2/6-311++g(2df,p) optimized geometry of all the 14 adenine tautomers, the first three vertical ionization energies have been calculated using several electron propagator decouplings. The corresponding Dyson orbitals provide detailed insight into the role of structural variations in different adenine tautomers. Changes in the electron binding energies and the corresponding Dyson orbital amplitudes have been correlated with tautomeric proton shifts and changes in conjugation patterns. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 [source] Cadherin expression pattern in melanocytic tumors more likely depends on the melanocyte environment than on tumor cell progressionJOURNAL OF CUTANEOUS PATHOLOGY, Issue 1 2004Sven Krengel Background:, Adhesion molecules have been assigned an important role in melanocytic tumor progression. By the loss of E-cadherin, melanocytes might escape the control of neighbouring keratinocytes. Although in vitro data support this hypothesis, there are yet no conclusive immunohistochemical results on cadherin expression in melanocytic tumors. Objective:, To gain detailed insight in the expression of cadherins and their cytoplasmic binding partners, the catenins, in various types of benign and malignant melanocytic neoplasms. Methods:, Immunohistochemical analysis of the expression of E-, P-, and N-cadherin and ,-, ,-, and ,-catenin in compound and dermal nevi, Spitz nevi, blue nevi, ultraviolet B (UVB)-irradiated nevi, and malignant melanomas of various tumor thickness. Results:, In both nevi and melanomas, E-cadherin expression in melanocytic cells decreased, following a gradient from junctional to deeper dermal localization. The pattern of E-cadherin expression was more heterogeneous in melanomas than in nevi. In some melanomas, E-cadherin was only weakly positive in the epidermal tumor cells. P-cadherin expression was similar to that of E-cadherin. N-cadherin expression in melanocytic lesions was a rare finding, however, a small percentage of melanomas showed expression in some cell nests. Some Spitz nevi exhibited strong N-cadherin immunoreactivity. Most melanocytic cells were ,- and ,-catenin-positive and ,-catenin-negative. UVB irradiation did not influence the expression of cadherins and catenins in melanocytic nevi in vivo. Conclusions:, It is presumed that the gradual loss of E-cadherin expression represents a reaction of melanocytic cells to altered conditions in the dermal environment, e.g. lack of contact to keratinocytes, or new contact with dermal extracellular matrix molecules, respectively. Melanoma cells apparently are less dependent on these environmental factors and, therefore, show a more heterogeneous expression pattern. This might be of importance for the adaptation of the tumor cells to local requirements. However, in view of our results, a causative role of (loss of ) E-cadherin or (gain of ) N-cadherin for melanocytic tumor progression still remains to be proven. [source] The fast and the curious: High-throughput experimentation in synthetic polymer chemistryJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2003Richard Hoogenboom Abstract The application of automated synthetic parallel methods in polymer chemistry is described. A brief overview of all different polymerization techniques that have been used is provided. Furthermore, the equipment and methodologies that were used in our approach for automated parallel polymerization reactions are discussed followed by detailed insight into recent developments on automated cationic ring-opening polymerization, atom transfer radical polymerization, and emulsion polymerizations. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2425,2434, 2003 [source] Quantitative MRI for the assessment of bone structure and function,NMR IN BIOMEDICINE, Issue 7 2006Felix W. Wehrli Abstract Osteoporosis is the most common degenerative disease in the elderly. It is characterized by low bone mass and structural deterioration of bone tissue, leading to morbidity and increased fracture risk in the hip, spine and wrist,all sites of predominantly trabecular bone. Bone densitometry, currently the standard methodology for diagnosis and treatment monitoring, has significant limitations in that it cannot provide information on the structural manifestations of the disease. Recent advances in imaging, in particular MRI, can now provide detailed insight into the architectural consequences of disease progression and regression in response to treatment. The focus of this review is on the emerging methodology of quantitative MRI for the assessment of structure and function of trabecular bone. During the past 10 years, various approaches have been explored for obtaining image-based quantitative information on trabecular architecture. Indirect methods that do not require resolution on the scale of individual trabeculae and therefore can be practiced at any skeletal location, make use of the induced magnetic fields in the intertrabecular space. These fields, which have their origin in the greater diamagnetism of bone relative to surrounding marrow, can be measured in various ways, most typically in the form of R2,, the recoverable component of the total transverse relaxation rate. Alternatively, the trabecular network can be quantified by high-resolution MRI (µ-MRI), which requires resolution adequate to at least partially resolve individual trabeculae. Micro-MRI-based structure analysis is therefore technically demanding in terms of image acquisition and algorithms needed to extract the structural information under conditions of limited signal-to-noise ratio and resolution. Other requirements that must be met include motion correction and image registration, both critical for achieving the reproducibility needed in repeat studies. Key clinical applications targeted involve fracture risk prediction and evaluation of the effect of therapeutic intervention. Copyright © 2006 John Wiley & Sons, Ltd. [source] The Inheritance of Chilling Tolerance in Tomato (Lycopersicon spp.)PLANT BIOLOGY, Issue 2 2005J. H. Venema Abstract: During the past 25 years, chilling tolerance of the cultivated (chilling-sensitive) tomato Lycopersicon esculentum and its wild, chilling-tolerant relatives L. peruvianum and L. hirsutum (and, less intensively studied, L. chilense) has been the object of several investigations. The final aim of these studies can be seen in the increase in chilling tolerance of the cultivated genotypes. In this review, we will focus on low-temperature effects on photosynthesis and the inheritance of these traits to the offspring of various breeding attempts. While crossing L. peruvianum (,) to L. esculentum (,) so far has brought the most detailed insight with respect to physiological questions, for practical purposes, e.g., the readily cross ability, crossing programmes with L. hirsutum as pollen donor at present seem to be a promising way to achieve higher chilling-tolerant genotypes of the cultivated tomato. This perspective is due to the progress that has been made with respect to the genetic basis of chilling tolerance of Lycopersicon spp. over the past five years. [source] Isolation of p53-target genes and their functional analysisCANCER SCIENCE, Issue 1 2004Yusuke Nakamura Mutations of the p53 gene are the most common genetic alterations found in human cancers, and are known to play crucial roles in tumor development and progression. The p53 gene encodes a protein functioning as a transcription factor, and the biological functions of p53 are manifested through the activities of its downstream genes. Identification of these downstream genes involved in the p53-signaling pathway should provide more detailed insight into the molecular mechanisms that mediate tumor-suppressor activities, as well as various responses to cellular stress. We have been attempting to isolate p53-target genes by means of various approaches, including differential display, cDNA microarray analysis, and direct cloning of the p53-binding sequences from human genomic DNA. Here I review our recent work on isolation of p53-target genes and their functional analysis. The physiological functions of p53-target genes include apoptosis (GML, p53AIP1, and STAG1), DNA repair (p53R2), inhibition of angiogenesis (BAI1), re-entry into the cell cycle (p53RFP), oxidative stress (CSR), and determination of cell fate (p53RDL1). (Cancer Sci 2004; 95: 7,11) [source] Chirally Modified Platinum Generated by Adsorption of Cinchonidine Ether Derivatives: Towards Uncovering the Chiral SitesCHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2007Norberto Bonalumi Abstract The adsorption behavior of O -methyl and O -trimethylsilyl derivatives of cinchonidine (CD), employed as chiral modifiers for heterogeneous enantioselective hydrogenations on supported Pt catalysts, has been investigated by using attenuated total reflection infrared spectroscopy (ATR-IR) and density functional theory (DFT) electronic structure calculations. The ATR-IR spectroscopic investigation provided detailed insight of the adsorbed modifiers under conditions close to those employed during catalytic processes, and electronic structure calculations were used as a complement to the experiments to uncover the implications of conformational changes in generating the topology of the surface chiral site. The structural investigation of the adsorbed modifiers revealed a relationship between the spatial positions of the ether substituents and the enantiodifferentiation induced by the modified catalyst observed in the hydrogenation of ,-activated ketones. Experiments and calculations corroborate a model, according to which the addition of a bulky ether group to CD reshapes the chiral sites, thus generating catalytic chiral surfaces with different and, in some cases (e.g. hydrogenation of ketopantolactone), even opposite enantioselective properties to those obtained with CD without altering the absolute configuration of the modifier. The study also confirms that active surface conformations of cinchona modifiers are markedly different from those existing in vacuum and in solution, thus underlying the necessity of investigating the surface-modifier interaction in order to understand enantioselectivity. [source] A Combined ESI- and MALDI-MS(/MS) Study of Peripherally Persulfonylated Dendrimers: False Negative Results by MALDI-MS and Analysis of Defects,CHEMISTRY - A EUROPEAN JOURNAL, Issue 19 2005Thorsten Felder Dipl.-Chem. Abstract Mass spectrometry, in particular MALDI-MS, has often been used as a valuable means to characterize dendritic molecules with respect to their molecular masses. Also, it is a valuable tool for analyzing potential defects in their structure which result from incomplete synthetic steps. This article presents a comparison of ESI and MALDI mass spectrometric experiments on dendrimers persulfonylated at their periphery. While the ESI mass spectra easily permit impurities and defects to be identified and thus provide evidence for sample purity, reactions with acidic matrices occur during the MALDI process. The resulting defects are identical to those expected from incomplete substitution. Thus, in these cases, MALDI-MS yields false negative results. With mass-selected, ESI-generated ions, collision experiments were performed in an FT-ICR mass spectrometer cell to provide detailed insight into the fragmentation patterns of the various dendrimers. Different fragmentation patterns are observed depending on the exact structure of the dendrimer. Also, the nature of the charge is important. The fragmentation reactions for protonated species differ much from those binding a sodium or potassium ion. These differences can be traced back to different sites for binding H+ versus Na+ or K+. Tandem MS experiments on mass-selected dendrimer ions with defects can be used to distinguish different types of defects. A concise structural assignment can thus be made on the basis of these experiments. Even mixtures of two isobaric defect variants with the same elemental composition can be identified. Massenspektrometrie, insbesondere MALDI-MS wurde oft als wertvolle Analysenmethode für die Charakterisierung von Dendrimeren hinsichtlich ihrer Molekülmasse, aber auch hinsichtlich einer Analyse potentieller Strukturdefekte eingesetzt, die aus unvollständig verlaufenden Synthesestufen resultieren. In diesem Artikel berichten wir über einen Vergleich von ESI- und MALDI-massenspektrometrischen Experimenten mit an ihrer Peripherie persulfonylierten Dendrimeren. Während die ESI-Massenspektren eine einfache Identifizierung von Verunreinigungen und Defekten erlauben und damit eine Reinheitskontrolle ermöglichen, laufen während der Ionisierung mittels MALDI Reaktionen mit sauren Matrices ab, die genau solche Defekte erzeugen, wie man sie aus einer unvollständigen Synthese erwarten würde. MALDI-MS führt hier also zu einem falsch-negativen Ergebnis. Mit massenselektierten Ionen aus der Electrospray-Ionisierung wurden Stoßexperimente in einer FT-ICR-Zelle durchgeführt, um einen detaillierten Einblick in das Fragmentierungsmuster der verschiedenen Dendrimere zu erhalten. Man beobachtet unterschiedliche Fragmentierungsmuster in Abhängigkeit von der genauen Struktur der Dendrimere. Auch die Art der Ladung ist wichtig, da die Fragmentierungswege der protonierten Dendrimere sich deutlich von denen ihrer Na+ - und K+ -Addukte unterscheiden. Diese Unterschiede können auf unterschiedliche Bindungsstellen für H+gegenüber Na+oder K+zurückgeführt werden. Tandem MS-Experimente mit massenselektierten, strukturdefekten Dendrimer-Ionen erlauben eine genaue Unterscheidung verschiedener Typen von Defekten. Sie können daher für eine detaillierte Strukturaufklärung verwendet werden. Sogar Mischungen zweier isobarer Defektvarianten mit gleicher Elementarzusammensetzung werden zuverlässig identifiziert. [source] Structural and functional insights into Erwinia carotovora l -asparaginaseFEBS JOURNAL, Issue 17 2008Anastassios C. Papageorgiou Bacterial l -asparaginases are enzymes that catalyze the hydrolysis of l -asparagine to aspartic acid. For the past 30 years, these enzymes have been used as therapeutic agents in the treatment of acute childhood lymphoblastic leukemia. Their intrinsic low-rate glutaminase activity, however, causes serious side-effects, including neurotoxicity, hepatitis, coagulopathy, and other dysfunctions. Erwinia carotovora asparaginase shows decreased glutaminase activity, so it is believed to have fewer side-effects in leukemia therapy. To gain detailed insights into the properties of E. carotovora asparaginase, combined crystallographic, thermal stability and cytotoxic experiments were performed. The crystal structure of E. carotovoral -asparaginase in the presence of l -Asp was determined at 2.5 Å resolution and refined to an Rcryst of 19.2 (Rfree = 26.6%) with good stereochemistry. Cytotoxicity measurements revealed that E. carotovora asparaginase is 30 times less toxic than the Escherichia coli enzyme against human leukemia cell lines. Moreover, denaturing experiments showed that E. carotovora asparaginase has decreased thermodynamic stability as compared to the E. coli enzyme and is rapidly inactivated in the presence of urea. On the basis of these results, we propose that E. carotovora asparaginase has limited potential as an antileukemic drug, despite its promising low glutaminase activity. Our analysis may be applicable to the therapeutic evaluation of other asparaginases as well. [source] Creole Materialities: Archaeological Explorations of Hybridized Realities on a North American PlantationJOURNAL OF HISTORICAL SOCIOLOGY, Issue 1 2010STEPHEN A. MROZOWSKI This paper explores the hybridized realities of European, Native American and Afro-Caribbean/Afro-American residents of Sylvester Manor, New York and Constant Plantation, Barbados during the seventeenth century. It draws on archaeological and landscape evidence from two plantations that were owned and operated by different members of the same family during the seventeenth century. One of plantations, known as Sylvester Manor, encompassed all 8,000 acres of Shelter Island, New York. It was established in 1652 primarily to help in the provisioning of two large sugar plantations on Barbados, Constant and Carmichael plantations. Sylvester Manor was operated by Nathaniel Sylvester; an Englishman who spent the first twenty years of life living in Amsterdam where his father was a merchant. Constant and Carmichael plantations were operated by his brother Constant Sylvester. Both the Barbados and New York plantations relied upon a labor force of enslaved Afro-Caribbean's. Archaeological evidence from Sylvester Manor has also revealed that Native American laborers played a prominent role in the daily activities of this northern plantation. Material and landscape evidence reveal the construction of hybridized identities that in the case of Barbados, are still part of the fabric of a postcolonial reality. Evidence from Sylvester Manor provides detailed insights into the construction of hybridized identities under the exigencies of a plantation economy whose global connections are dramatically visible in the archaeological record. [source] Characterization of 13 polymorphic microsatellite loci for two land snail species, Trochulus villosus and T. sericeus (Gastropoda: Pulmonata: Hygromiidae)MOLECULAR ECOLOGY RESOURCES, Issue 3 2008A. DÉPRAZ Abstract Thirteen new microsatellite loci were isolated and tested on two land snail species, Trochulus villosus and T. sericeus (Pulmonata: Hygromiidae), resulting in a set of eight polymorphic markers for each species. The expected heterozygosity was high for all loci and species (between 0.616 and 0.944). Such levels of variability will allow detailed insights into the population genetic structure of some Trochulus species. [source] Quantitative variability of cyanogenesis in Cathariostachys madagascariensis,the main food plant of bamboo lemurs in Southeastern MadagascarAMERICAN JOURNAL OF PRIMATOLOGY, Issue 4 2009Daniel J. Ballhorn Abstract Giant bamboo (Cathariostachys madagascariensis) is a major food plant for three sympatric species of bamboo-eating lemurs (Hapalemur aureus, H. griseus, and Prolemur simus) in the rain forests of southeastern Madagascar. This plant species is strongly cyanogenic. However, quantitative data on cyanide concentration in C. madagascariensis are scarce. Previous studies reported 15,mg cyanide per 100,g fresh shoot material (corresponding to approx. 57,µmol cyanide per gram dry weight). However, we found mean concentrations (±SE) ranging from 139.3±19.32 in ground shoots to 217.7±16.80,µmol cyanide per gram dry weight in branch shoots. Thus, cyanogenesis of C. madagascariensis was up to four times higher than reported before. In contrast to the strongly cyanogenic shoots no cyanide could be detected in differently aged leaves of C. madagascariensis confirming earlier studies. Within individual shoots fine-scaled analysis revealed a characteristic ontogenetic pattern of cyanide accumulation. Highest concentrations were found in youngest parts near the apical meristem, whereas concentrations decreased in older shoot parts. Beyond the general intra-individual variability of cyanogenic features analyses indicated site-specific variability of both, the ontogenetic pattern of cyanide concentration as well as the total amount of cyanide accumulated in shoots. Additionally, analyses of soluble proteins,one important nutritive measure affecting food plant quality,demonstrated a converse quantitative relation of protein concentrations in leaves to cyanide concentration in shoots at the site-specific level. We, thus, suggest integrative analyses on quantitative variation of cyanogenesis together with nutritive plant parameters in future studies. This approach would allow obtaining more detailed insights into spatial variability of giant bamboo's overall browse quality and its impact on lemur herbivores. Am. J. Primatol. 71:305,315, 2009. © 2009 Wiley-Liss, Inc. [source] Dynamics of growth and dissemination of Salmonella in vivoCELLULAR MICROBIOLOGY, Issue 10 2010Kathryn G. Watson Summary The last decade has witnessed increasing research on dissemination of bacterial pathogens in their hosts and on the processes that underlie bacterial spread and growth during organ colonization. Here, we discuss work on the mouse model of human typhoid fever caused by Salmonella enterica serovar Typhimurium. This has revealed the use of several routes of systemic dissemination that result in colonization and growth within the spleen and liver, the major sites of bacterial proliferation. We also highlight techniques that enable in vivo analysis of the infecting population at the spatiotemporal and single cell levels. These approaches have provided more detailed insights into the events underlying the dynamics of Salmonella replication, spread and clearance within host organs and tissues. [source] |