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Structure Present (structure + present)
Selected AbstractsMultigenerational analysis of spatial structure in the terrestrial, food-deceptive orchid Orchis masculaJOURNAL OF ECOLOGY, Issue 2 2009Hans Jacquemyn Summary 1In long-lived, terrestrial orchids, strong aggregation of adults and recruits within populations and pronounced spatial association between recruits and adults can be expected when seed dispersal is limited, probabilities of seed germination decrease with increasing distance from mother plants and/or not all mother plants contribute to future generations. When individuals are distributed evenly across life-history stages, these processes can also be expected to result in a significant fine-scale spatial genetic structure in recruits that will persist into the adult-stage class. 2We combined detailed spatial genetic and point pattern analyses across different generations with parentage analyses to elucidate the role of the diverse processes that might determine spatial structure in Orchis mascula. 3Analyses of spatial point patterns showed a significant association between adults and recruits and similar clustering patterns for both. Weak, but highly significant spatial genetic structure was observed in adults and recruits, but no significant differences were observed across life stages, indicating that the spatial genetic structure present in recruits persists into the adult stage. 4Parentage analyses highlighted relatively short seed dispersal distances (median offspring-recruitment distance: 1.55 and 1.70 m) and differential contribution of mother plants to future generations. 5Persistence of fine-scale spatial genetic structure from seedlings into the adult stage class is consistent with the life history of O. mascula, whereas relatively large dispersal distances of both pollen and seeds compared to the fine-scale clustering of adults and seedlings suggest overlapping seed shadows and mixing of genotypes within populations as the major factors explaining the observed weak spatial genetic structure. 6Nonetheless, comparison of the spatial association between recruits and adults with the genetic analysis of offspring-parent distances suggests that the tight clustering of recruits around adults was probably caused by decreasing probabilities of seed germination with increasing distance from mother plants. 7Synthesis. This study shows that the approach presented here, which combines spatial genetic and spatial pattern analyses with parentage analyses, may be broadly applied to other plant species to elucidate the processes that determine spatial structure within their populations. [source] Identification of a human estrogen receptor ,-derived antiestrogenic peptide that adopts a polyproline II conformationJOURNAL OF PEPTIDE SCIENCE, Issue 7 2009Josef Kapitán Abstract Polyproline II (PPII) helix is an extended secondary structure present in a number of proteins. PPII-containing sequences mediate specific protein,protein interactions with partners containing appropriate cognate domains called PPII-recognizing domains (PRDs) and are involved in the activation of intracellular signaling pathways. Thus, the identification of PPII structures in proteins is of great interest, not only to explore molecular and physiological mechanisms, but also to elaborate new potential drugs. By revisiting X-ray crystal structures of liganded ,-type human estrogen receptor (ER,), we have identified an 11-residue PPII-helical sequence (D321AEPPILYSEY331) in the ligand-binding domain of the receptor. The data recorded by far-ultraviolet circular dichroism (far-UV CD), vibrational Raman optical activity (ROA) and differential scanning calorimetry (DSC) show that the corresponding peptide (Ac-DAEPPILYSEY-NH2) is particularly well structured in PPII, with the same proportion of PPII as observed from X-ray structures (,85%). In addition, studies carried out on ER,-negative Evsa-T breast cancer cells transiently co-transfected with a pcDNA3-ER, plasmid and a Vit-tk-Luc reporter gene revealed that the peptide antagonizes the estradiol-induced transcription providing perspectives for researching new molecules with antagonistic properties. Copyright © 2009 European Peptide Society and John Wiley & Sons, Ltd. [source] Biostability and pharmacokinetics of LJP 920, an octameric Gal (,1,3) Gal conjugate for the inhibition of xenotransplantation rejectionJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 7 2001Lee Jia Antibodies to an ,-galactosyl saccharide structure present in human serum are associated with hyperacute rejection and delayed xenograft rejection after pig-to-primate xenotransplantation. To overcome this major barrier to the xenotransplantation, LJP 920, a galactosyl ,1,3 galactose (Gal (,1,3) Gal) coupled to a non-immunogenic platform at a valency of eight Gal (,1,3) Gal molecules/platform, was synthesized to clear circulating antibodies and to inhibit their production by B cells that produce these antibodies. Herein we report on the stability of LJP 920 in biological media and its pharmacokinetic profile. Incubation of LJP 920 with mouse serum or liver microsomes at 37°C for 2 days showed no indication of degradation of the conjugate as detected by a reversed-phase HPLC method, indicating that the conjugate is not subject to enzymatic metabolism. After intravenous administration of LJP 920 to mice at the doses of 20 and 100 mg kg,1, LJP 920 serum concentration decreased rapidly, showing a biphasic pattern, with a distribution half-life of 3 min and an elimination half-life of more than 30 min, respectively. The serum-to-erythrocyte concentration ratio of LJP 920 was 33- and 36-fold excess at 0.5 and 5 min, respectively, after intravenous administration (100 mg kg,1). Both Cmax and AUC values increased in a dose-proportional manner. LJP 920 displayed a great distribution to well-perfused tissues. It was eliminated mainly through renal excretion in the unchanged form, which accounted for 23% of the total amount within 8 h of dosing. [source] Pressure- and temperature-dependent Raman studies of KNbW2O9 hexagonal tungsten bronzeJOURNAL OF RAMAN SPECTROSCOPY, Issue 3 2003czka Abstract Pressure- and temperature-dependent Raman studies were performed on KNbW2O9 ferroelectric hexagonal tungsten bronze single crystal. The results suggest that some structural changes, possibly phase transitions, connected with tilting of the WO6 octahedra occur in this material at around 290,350 K and 1.0,1.4 GPa. No changes in the spectra could be observed at the 523 and 543,553 K phase transitions. The data indicate that these phase transitions lead to only weak changes in the vibrational properties of KNbW2O9, which were not observed owing to the large bandwidth of the Raman bands. The Raman studies suggest, therefore, that the structure of the unknown phase, existing below 553 K, differs slightly form the orthorhombic structure present above 553 K. The pressure-dependent study revealed that the 52 cm,1 band, assigned to external vibrations of the WO6 octahedron, consists at ambient temperature and pressure of two overlapping bands. These bands become well separated at high pressure. Copyright © 2003 John Wiley & Sons, Ltd. [source] Atmospheric pressure chemical ionisation reversed-phase liquid chromatography/ion trap mass spectrometry of intact bacteriohopanepolyolsRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 7 2003Helen M. Talbot Atmospheric pressure chemical ionisation liquid chromatography/multi-stage ion trap mass spectrometry (APCI-LC/MSn) has been applied to the study of intact bacteriohopanepolyols. Spectral characterisation of bacteriohopanepolyols of known structure present in bacterial extracts (Zymomonas mobilis and a fermenter containing methanotrophs including Methylococcus capsulatus) has revealed greater structural detail than previous liquid chromatography/mass spectrometry (LC/MS) methods and identified characteristic fragmentations indicative of numerous biohopanoid structures. Analysis of a Recent sedimentary extract from Lake Druzhby (Antarctica) has demonstrated the power of this technique to detect biohopanoids in complex samples including at least partial characterisation of previously unknown composite structures. Copyright © 2003 John Wiley & Sons, Ltd. [source] In1.08Gd0.92Ge2O7: a new member of the thortveitite familyACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2002Erick-Adrian Juarez-Arellano Indium gadolinium digermanium heptaoxide, In1.08Gd0.92Ge2O7, with a thortveitite-type structure, has been prepared as a polycrystalline powder material by a high-temperature solid-state reaction. As in the mineral thortveitite, the crystal structure belongs to the monoclinic system, with space group C2/m (No. 12). The precise structural parameters were obtained by applying the Rietveld method of refinement to the X-ray powder diffraction data. This layered structure presents, on one side, a honeycomb-like arrangement of the unique octahedral site, which is occupied randomly by In and Gd atoms, and, on the other side, sheets of isolated Ge2O7 diortho-groups made up of double tetrahedra sharing a common vertex and displaying C2h point symmetry. This compound showed a remarkable photoluminescence effect when it was irradiated with the X-ray beam during the X-ray diffraction measurements, and with the , beam during the Rutherford back-scattering spectrometry experiments employed to analyze the chemical stoichiometry. [source] Developing Expert Medical Teams: Toward an Evidence-based ApproachACADEMIC EMERGENCY MEDICINE, Issue 11 2008Rosemarie Fernandez MD Abstract Current health care literature cites communication breakdown and teamwork failures as primary threats to patient safety. The unique, dynamic environment of the emergency department (ED) and the complexity of patient care necessitate the development of strong interdisciplinary team skills among emergency personnel. As part of the 2008 Academic Emergency Medicine Consensus Conference on "The Science of Simulation in Healthcare," our workshop group identified key theory and evidence-based recommendations for the design and implementation of team training programs. The authors then conducted an extensive review of the team training literature within the domains of organizational psychology, aviation, military, management, and health care. This review, in combination with the workshop session, formed the basis for recommendations and need for further research in six key areas: 1) developing and refining core competencies for emergency medicine (EM) teams; 2) leadership training for emergency physicians (EPs); 3) conducting comprehensive needs analyses at the organizational, personnel, and task levels; 4) development of training platforms to maximize knowledge transfer; 5) debriefing and provision of feedback; and 6) proper implementation of simulation technology. The authors believe that these six areas should form an EM team training research platform to advance the EM literature, while leveraging the unique team structures present in EM to expand team training theory and research. [source] | |||||||||||||