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Structural Variants (structural + variants)
Selected AbstractsDisorders of the synthesis of human fetal hemoglobinIUBMB LIFE, Issue 2 2008Laura Manca Abstract Fetal hemoglobin (HbF), the predominant hemoglobin in the fetus, is a mixture of two molecular species (,2G,2 and ,2A,2) that differ only at position 136 reflecting the products of two nonallelic ,-globin genes. At the time of birth, HbF accounts for ,70% of the total Hb. The G,:A, globin ratio in the HbF of normal newborn is 70:30 whereas in the trace amounts of HbF that is found in the adult it reverses to 40:60 because of a ,- to ,-globin gene switch. Alterations of these ratios are indicative of a molecular defect at the level of the HbF synthesis. Qualitative hemoglobinopathies due to G, and A, chain structural variants, and quantitative hemoglobinopathies affecting the synthesis of HbF such as ,-thalassemias, duplications, triplications, and even sextuplications of the ,-globin genes, which may be detected in newborn blood lysates, have been described. Moreover, several pathological and nonpathological conditions affecting the ,-globin gene cluster, such as ,-thalassemia, sickle cell disease, ,,-thalassemia, and hereditary persistence of HbF syndromes, are characterized by the continued synthesis of ,-globin chains in the adult life. Studies of these natural mutants associated with increased synthesis of HbF in adult life have provided considerable insight into the understanding of the control of globin gene expression and Hb switching. © 2008 IUBMB IUBMB Life, 60(2): 94,111, 2008 [source] Synthesis and biological evaluation of structural variants of carbazoquinocin CJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 3 2003Alparslan Aygün Some new structural variants of the alkaloid carbazoquinocin C were synthesized in a few steps with good to excellent yields. The key step comprises a cyclisation reaction of appropriate 2-vinylindoles with oxalyl chloride. The carbazole-3,4-quinones are able to trap oxygen-centred radicals. In some biological/biochemical assays some of these compounds exhibit extraordinary results including inhibition of cyclooxygenase-1 and 5-lipoxygenase in the ,M-range. Moreover some of the carbazoquinocin C-variants inhibit significant oxidative damage of cellular DNA in nM-range. [source] The significance of platelet-activating factor and fertility in the male primate: a reviewJOURNAL OF MEDICAL PRIMATOLOGY, Issue 1 2005William E. Roudebush Abstract:, Since its discovery nearly 30 years ago platelet-activating factor (PAF) has emerged as one of the more important lipid mediators known. PAF (1- O -alkyl-2- O -acetyl- sn -glycero-3-phosphorylcholine) exists endogenously as a mixture of molecular species with structural variants of the alkyl moiety. PAF is a novel potent signaling phospholipid that has unique pleiotropic biological properties in addition to platelet activation. PAF also plays a significant role in reproduction and is present in the sperm of a number of primate species. PAF content in squirrel monkey sperm is significantly higher during the breeding season than the non-breeding season. PAF content in rhesus sperm has a significant relationship with sperm motility. PAF content in human sperm has a positive correlation with seminal parameters and pregnancy outcomes. The enzymes (lyso-PAF-acetyltransferase and PAF-acetylhydrolase) necessary for PAF activation and deactivation are present in primate sperm. PAF-acetylhydrolase may act as a ,decapacitation factor'. Removal of this enzyme during capacitation promotes PAF synthesis increasing primate motility and fertilization. PAF also plays a significant role in the fertilization process, enhancing the fertilization rates of oocytes. Enhanced embryo development has also been reported in oocytes fertilized with PAF-treated sperm. Exogenous PAF will also significantly improve primate artificial insemination pregnancy outcomes. PAF antagonists inhibit sperm motility, acrosome reaction, and fertilization thus suggesting the presence of receptors for PAF. The PAF-receptor is present on primate sperm, with altered transcript levels and distribution patterns on abnormal cells. Whereas, the exact mechanism of PAF in sperm function and reproduction is uncertain, its importance in normal primate fertility is substantial. [source] Transmission electron microscopy and theoretical analysis of AuCu nanoparticles: Atomic distribution and dynamic behaviorMICROSCOPY RESEARCH AND TECHNIQUE, Issue 7 2006J.A. Ascencio Abstract Though the application of bimetallic nanoparticles is becoming increasingly important, the local atomistic structure of such alloyed particles, which is critical for tailoring their properties, is not yet very clearly understood. In this work, we present detailed study on the atomistic structure of Au,Cu nanoparticles so as to determine their most stable configurations and the conditions for obtaining clusters of different structural variants. The dynamic behavior of these nanoparticles upon local heating is investigated. AuCu nanoparticles are characterized by high resolution transmission electron microscopy (HRTEM) and energy filtering elemental composition mapping (EFECM), which allowed us to study the internal structure and the elemental distribution in the particles. Quantum mechanical approaches and classic molecular dynamics methods are applied to model the structure and to determine the lowest energy configurations, the corresponding electronic structures, and understand structural transition of clusters upon heating, supported by experimental evidences. Our theoretical results demonstrate only the core/shell bimetallic structure have negative heat of formation, both for decahedra and octahedral, and energetically favoring core/shell structure is with Au covering the core of Cu, whose reverse core/shell structure is not stable and may transform back at a certain temperature. Experimental evidences corroborate these structures and their structural changes upon heating, demonstrating the possibility to manipulate the structure of such bimetallic nanoparticles using extra stimulating energy, which is in accordance with the calculated coherence energy proportions between the different configurations. Microsc. Res. Tech., 2006. © 2006 Wiley-Liss, Inc. [source] From Warrior to Wife: Cultural Transformation in the Gamo Highlands of EthiopiaTHE JOURNAL OF THE ROYAL ANTHROPOLOGICAL INSTITUTE, Issue 1 2002Dena Freeman This article focuses on cultural transformation in the Gamo Highlands of Ethiopia and seeks to explain the way in which certain initiation rituals have transformed over time. The article begins by considering two structural variants of the initiation ritual that exist in two neighbouring communities, Doko Gembela and Doko Masho, and argues that one is an historical transformation of the other. After comparing the contemporary form of these two variants, the article then moves to consider the macro-level forces of change that have impinged on the two communities over the past two hundred years or so. It then seeks to bring ethnography and history together by considering how the macro-level changes might have been experienced in the interpersonal relations of individuals. It explores the new types of situations that would have arisen and discusses how these new situations would have put strains on particular interpersonal relations, leading in many cases to conflict and dispute. After describing the local methods of conflict resolution, it is shown that on some occasions solutions are found which involve communal decisions to make a small change in cultural practice. In some cases these small changes have a knock-on effect leading to overall structural change. The article ends with a hypothetical reconstruction of the way in which the Doko Masho initiation rituals might have transformed. [source] Lack of genetic association of promoter and structural variants of mannan-binding lectin (MBL2) gene with susceptibility to generalized vitiligoBRITISH JOURNAL OF DERMATOLOGY, Issue 1 2009M. Dwivedi Summary Background, Vitiligo is a common depigmenting disorder resulting from the loss of functional melanocytes in the skin. It is hypothesized to be of autoimmune origin. Mannan-binding lectin (MBL) plays an important role in innate immunity. It helps in the clearance of apoptotic cells and in complement activation. Genetic variability due to structural and promoter polymorphisms in the MBL2 gene has been reported to be associated with increased risk for several autoimmune diseases including vitiligo. Objectives, The aim of this study was to explore whether MBL2 structural and promoter polymorphisms are associated with generalized vitiligo in Gujarat where the prevalence of vitiligo is alarmingly high. Materials and methods, We undertook a case,control study to investigate the association of MBL2 gene exon 1 polymorphisms , codon 52, codon 54 and codon 57 as well as promoter ,221 polymorphism in 92 patients with generalized vitiligo and 94 unaffected age-matched controls by polymerase chain reaction-heteroduplex analysis. Results, The genotype and allele frequencies of MBL2 structural and promoter polymorphisms did not differ significantly between the control and patient population (P -values: P < 0·019 for codon 52, P < 0·373 for codon 54, P < 0·855 for codon 57 and P < 0·889 for ,221 promoter polymorphisms) after Bonferroni's correction for multiple testing, which suggests that there is no association of MBL2 structural and promoter polymorphisms with generalized vitiligo. Conclusions, Our results suggest that the well-documented structural and promoter polymorphisms of the MBL2 gene may not be associated with generalized vitiligo in the Gujarat population. [source] Hierarchical gene expression profiles of HUVEC stimulated by different lipid A structures obtained from Porphyromonas gingivalis and Escherichia coliCELLULAR MICROBIOLOGY, Issue 4 2007Casey Chen Summary The ability of lipid A structural variants to elicit unique endothelial cell gene expression was examined by measuring global gene expression profiles in human umbilical cord vein endothelial cells (HUVEC) using Affymetrix full genome chips. Two lipid A structural variants obtained from Porphyromonas gingivalis designated PgLPS1435/1449 and PgLPS1690 as well as LPS obtained from Escherichia coli wild type and an E. coli msbB mutant (missing myristic acid in the lipid A) were examined. Each of these lipid A structures has been shown to interact with TLR4; however, PgLPS1435/1449 and E. coli msbB LPS have been shown to be TLR4 antagonists while PgLPS1690 and wild-type E. coli LPS are TLR4 agonists. It was found that PgLPS1435/1449 and PgLPS1690 as well as E. coli msbB LPS activated a subset of those genes significantly transcribed in response to E. coli wild-type LPS. Furthermore, the subset of genes expressed in response to the different lipid A structural forms were those most significantly activated by wild-type E. coli LPS demonstrating a hierarchy in TLR4-dependent endothelial cell gene activation. A unique gene expression profile for the weak TLR4 agonist PgLPS1690 was observed and represents a TLR4 hierarchy in endothelial cell gene activation. [source] | |||||||||||||