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Selected AbstractsCnidarians and the evolutionary origin of the nervous systemDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 3 2009Hiroshi Watanabe Cnidarians are widely regarded as one of the first organisms in animal evolution possessing a nervous system. Conventional histological and electrophysiological studies have revealed a considerable degree of complexity of the cnidarian nervous system. Thanks to expressed sequence tags and genome projects and the availability of functional assay systems in cnidarians, this simple nervous system is now genetically accessible and becomes particularly valuable for understanding the origin and evolution of the genetic control mechanisms underlying its development. In the present review, the anatomical and physiological features of the cnidarian nervous system and the interesting parallels in neurodevelopmental mechanisms between Cnidaria and Bilateria are discussed. [source] Caught in a Trap?ECONOMICA, Issue 268 2000Wage Mobility in Great Britain: 197 In this paper I study wage mobility in Great Britain using the New Earnings Surveys of 1975,94 and the British Household Panel Surveys of 1991,94. Measuring mobility in terms of decile transition matrices, I find a considerable degree of immobility within the wage distribution from one year to the next. Mobility is higher when measured over longer time periods. Those in lower deciles in the wage distribution are much more likely to exit into unemployment and non-employment. Measuring mobility by studying changes in individuals' actual percentile rankings in the wage distribution, I find evidence that short-run mobility rates have fallen since the late 1970s. This has potentially important welfare implications, given the rise in cross-section earnings inequality observed over the last two decades. [source] In vitro determination of active bile acid absorption in small biopsy specimens obtained endoscopically or surgically from the human intestineEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 2 2002K-A. Ung Abstract Background In the construction of a Kock reservoir for continent urinary diversion, 70 cm of the distal ileum are used. Impaired absorption of bile acids in these patients might cause diarrhoea. Data on the absorption of bile acids in different parts of the human intestine are limited. Methods Biopsies were taken during endoscopy from the duodenum, the terminal ileum or the right colon, and during surgery 10, 50, 100 and 150 cm proximally to the ileo-caecal valve using standard endoscopy biopsy forceps. The biopsy specimens were incubated in vitro with radio-labelled taurocholic acid at 37 °C for 22 or 45 min The radioactivity was determined using the liquid scintillation technique. Results A linear increase in the uptake was observed, with increased concentrations of taurocholic acid between 100 and 500 µm in all specimens tested, that represented passive uptake or unspecific binding. The active uptake could be calculated from the intercept of the line representing passive uptake with the ordinate. The active uptake in the terminal ileum was 3,4 times greater than 100 cm proximal to the valve. Conclusions The active absorption of bile acids in humans can be determined in small biopsy specimens taken using standard biopsy forceps during endoscopy or surgery. This method is suitable for clinical studies of bile acid absorption. Active uptake of bile acids not only takes place in the very distal part of the ileum but also to a considerable degree 100 cm proximally to the ileo-colonic valve. This should be taken into account when selecting the ileal segment for continent urinary diversion. [source] Delimiting morphologically identical varieties of soybean [Glycine max (L.) Merr.] using lipoxygenase activitity levelFEDDES REPERTORIUM, Issue 3-4 2005M. S. Ayodele The occurrence of beany flavour resulting from lipoxygenase activity in soybeans was sufficiently manifested in all the 22 varieties of soybean investigated. There were significant differences in the level of lipoxygenase activity among varieties. A positive correlation was observed between lipoxygenase activity and beany flavour. Lipoxygenase activity level was found reliable in delimiting the varieties. A considerable degree of overlaps and associations were observed among the varietal grouping based on lip- oxygenase activity values. Such overlaps corroborate the reported closeness of plant morphological attributes of the varieties. Lipoxygenase activity was therefore, considered a reliable chemotaxonomic tool that could be useful for taxa delimitation, where there are very similar morphological attributes that may hinder easy delimitation. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Abgrenzung von morphologisch identischen Varietäten der Soyabohne [Glycine max (L.) Merr.] mittels aktiver Lipoxygenase Das Auftreten eines bohnenähnlichen Geruchs (soybean flavour) als Ergebnis der Lipoxygenase-Aktivität wurde in allen untersuchten 22 Sojabohnen-Sorten eindeutig nachgewiesen. Im Niveau der Lipoxygenase-Aktivität treten zwischen den einzelnen Sorten manifeste Unterschiede auf. Zwischen der Lipoxygenase-Aktivität und dem bohnenartigen Geruch wurde eine positive Korrelation beobachtet. Die Höhe der Lipoxygenase-Aktivität trennt die Sorten zuverlässig. Ein beträchtlicher Grad an Überschneidungen und von Gemeinsamkeiten wurde zwischen den auf Grund der Lipoxygenase-Aktivitätswerte gebildeten Sortengruppen gefunden. Die Überschneidungen bestätigen die Nähe der morphologischen Merkmale der Sorten. Die Lipoxygenase-Aktivität wird daher als eine verlässliche taxonomische Hilfe für die Trennung der Sippen angesehen, deren große morphologische Nähe eine leichte Trennung erschwert. [source] Functional biodiversity of macroinvertebrate assemblages along major ecological gradients of boreal headwater streamsFRESHWATER BIOLOGY, Issue 9 2005JANI HEINOArticle first published online: 3 AUG 200 Summary 1. Biodiversity,environment relationships are increasingly well-understood in the context of species richness and species composition, whereas other aspects of biodiversity, including variability in functional diversity (FD), have received rather little rigorous attention. For streams, most studies to date have examined either taxonomic assemblage patterns or have experimentally addressed the importance of species richness for ecosystem functioning. 2. I examined the relationships of the functional biodiversity of stream macroinvertebrates to major environmental and spatial gradients across 111 boreal headwater streams in Finland. Functional biodiversity encompassed functional richness (FR , the number of functional groups derived from a combination of functional feeding groups and habit trait groups), FD , the number of functional groups and division of individuals among these groups, and functional evenness (FE , the division of individuals among functional groups). Furthermore, functional structure (FS) comprised the composition and abundance of functional groups at each site. 3. FR increased with increasing pH, with additional variation related to moss cover, total nitrogen, water colour and substratum particle size. FD similarly increased with increasing pH and decreased with increasing canopy cover. FE decreased with increasing canopy cover and water colour. Significant variation in FS was attributable to pH, stream width, moss cover, substratum particle size, nitrogen, water colour with the dominant pattern in FS being related to the increase of shredder-sprawlers and the decrease of scraper-swimmers in acidic conditions. 4. In regression analysis and redundancy analysis, variation in functional biodiversity was not only related to local environmental factors, but a considerable proportion of variability was also attributable to spatial patterning of environmental variables and pure spatial gradients. For FR, 23.4% was related to pure environmental effects, 15.0% to shared environmental and spatial effects and 8.0% to spatial trends. For FD, 13.8% was attributable to environmental effects, 15.2% to shared environmental and spatial effects and 5% to spatial trends. For FE, 9.0% was related to environmental variables, 12.7% to shared effects of environmental and spatial variables and 4.5% to spatial variables. For FS, 13.5% was related to environmental effects, 16.9% to shared environmental and spatial effects and 15.4% to spatial trends. 5. Given that functional biodiversity should portray variability in ecosystem functioning, one might expect to find functionally rather differing ecosystems at the opposite ends of major environmental gradients (e.g. acidity, stream size). However, the degree to which variation in the functional biodiversity of stream macroinvertebrates truly portrays variability in ecosystem functioning is difficult to judge because species traits, such as feeding roles and habit traits, are themselves strongly affected by the habitat template. 6. If functional characteristics show strong responses to natural environmental gradients, they also are likely to do so to anthropogenic environmental changes, including changes in habitat structure, organic inputs and acidifying elements. However, given the considerable degree of spatial structure in functional biodiversity, one should not expect that only the local environment and anthropogenic changes therein are responsible for this variability. Rather, the spatial context, as well as natural variability along environmental gradients, should also be explicitly considered in applied research. [source] The implications of P-glycoprotein in HIV: friend or foe?FUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 3 2005Andrew Owen Abstract P-glycoprotein (P-gp), coded by the ABCB1 gene, has a wide tissue distribution. The drug transporter is known to limit the bioavailability of a plethora of drugs and xenobiotics including the human immunodeficiency virus (HIV) protease inhibitors. There remains a considerable degree of debate in the literature with respect to the role of ABCB1 polymorphisms in HIV-treatment outcome and some studies have also implicated antiretroviral drugs as inducers of P-gp. Recent evidence indicates a role for P-gp in the inhibition of viral infectivity and/or release and cellular relationships with other infection-related proteins (and cholesterol). It is becoming increasingly clear that future studies on P-gp in HIV should consider both pharmacological and virological issues. [source] Women and Classical Translation in the Eighteenth CenturyGERMAN LIFE AND LETTERS, Issue 3 2006Hilary Brown Women in Germany first began to take up their pens in substantial numbers during the eighteenth century. One area where they apparently did not leave their mark was in the translation of classical literature, despite a wave of interest in the classics in the literary world at large. However, this article sheds new light on women's involvement in this field. It focuses on a handful of women who translated from Greek or Latin, namely Luise Gottsched (1713,62), Fräulein von Erath (?,1776) and Ernestine Christine Reiske (1735,98). It looks at the conditions in which they did so, at their presentation of the texts, and at contemporary reactions to their work. It shows that women could only make their way in this area in exceptional cases, and that they usually exercised a considerable degree of caution. Yet, in some rare instances, translation gave women a new freedom. A translator could put her name to works of a surprising nature, such as philosophy and erotica. Adopting the detached stance of translator meant she could publish texts which women at the time would probably never have dared to write themselves. Thus, the act of translation could open up new spheres of literary activity for women. [source] Why Do Governments Delegate Authority to Quasi-Autonomous Agencies?GOVERNANCE, Issue 2 2006The Case of Independent Administrative Authorities in France In recent years, there has been a considerable degree of delegation from governments to quasi-autonomous agencies. Various reasons have been put forward to explain why governments decide to delegate authority in this way. Some reasons are based on a transaction-cost approach, such as credible commitments. Other reasons are more contextual. For instance, governments may be responding to a process of cross-national policy transfer. In the literature on delegation some hypotheses have already been tested. Specifically, evidence has been found suggesting that governments create agencies to commit credibly to particular policy choices. However, other hypotheses, particularly ones based on contextual explanations, have proved much more difficult to operationalize. This article aims to help fill this gap. It does so by focusing on the creation of Independent Administrative Authorities in France. Does the qualitative evidence in this particular case corroborate the quantitative studies that have been undertaken elsewhere? [source] Stress and hippocampal plasticity: implications for the pathophysiology of affective disordersHUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue S1 2001Bruce S. McEwen Abstract The hippocampal formation, a structure involved in declarative, spatial and contextual memory, is a particularly sensitive and vulnerable brain region to stress and stress hormones. The hippocampus shows a considerable degree of structural plasticity in the adult brain. Stress suppresses neurogenesis of dentate gyrus granule neurons, and repeated stress causes atrophy of dendrites in the CA3 region. In addition, ovarian steroids regulate synapse formation during the estrous cycle of female rats. All three forms of structural remodeling of the hippocampus are mediated by hormones working in concert with excitatory amino acids (EAA) and N -methyl- D -aspartate (NMDA) receptors. EAA and NMDA receptors are also involved in neuronal death that is caused in pyramidal neurons by seizures and by ischemia and prolonged psychosocial stress. In the human hippocampus, magnetic resonance imaging studies have shown that there is a selective atrophy in recurrent depressive illness, accompanied by deficits in memory performance. Hippocampal atrophy may be a feature of affective disorders that is not treated by all medications. From a therapeutic standpoint, it is essential to distinguish between permanent damage and reversible atrophy in order to develop treatment strategies to either prevent or reverse deficits. In addition, remodeling of brain cells may occur in other brain regions. Possible treatments are discussed. Copyright © 2001 John Wiley & Sons, Ltd. [source] Mixed Dementia: Epidemiology, Diagnosis, and TreatmentJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 8 2002Dina Zekry MD Alzheimer's disease (AD) and vascular dementia (VaD) are the most frequent causes of dementia in older people. Although AD can be diagnosed with a considerable degree of accuracy, the distinction between isolated AD, VaD, and mixed dementia (MD), where both pathologies coexist in the same patient, remains a controversial issue and one of the most difficult diagnostic challenges. Although MD represents a very frequent pathology, especially in older people, as reported in neuropathological studies, the respective importance of degenerative and vascular lesions, their interaction in the genesis of dementia, and the mere existence of MD are still debated. Accurate diagnosis of MD is of crucial significance for epidemiological purposes and for preventive and therapeutic strategies. Until recently, pharmacological studies have generally focused on pure disease, AD or VaD, and have provided little information on the best therapeutic approach to MD. This article provides an overview of MD in older people. A retrospective review of the recent literature on prevalence, incidence, course, risk factors, diagnosis, and treatment of MD was performed. The article also emphasizes the need for further studies, including neuropsychological and functional evaluations, and neuroimaging and clinicopathological correlations to develop a better understanding of MD, which appears to be one of the most common forms of dementia. [source] Amplified fragment length polymorphism (AFLP) and biochemical typing of Photobacterium damselae subsp. damselaeJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2002S. Botella Aims: The aim of the present study was to characterize subspecifically Photobacterium damselae subsp. damselae strains isolated from cultured Sparus aurata and Dicentrarchus labrax by means of phenotypic and molecular typing techniques (amplified fragment length polymorphism, AFLP). Methods and Results: Seventy-one strains of P. damselae subsp. damselae were isolated from 38 cultured fishes at different fish farms located on the Mediterranean coast near Valencia, Spain. Most fish studied were asymptomatic and some were recovered during infectious outbreaks. Phenotypic characterization revealed a considerable degree of variability within the subspecies, including some characters, such as production of urease, which are used to differentiate P. damselae subsp. damselae from P. damselae subsp. piscicida. Genetic characterization was conducted on a selection of 33 strains, including two reference strains. Dice coefficient (Sd) and the unweighted pair group method with average linkage (UPGMA) were used for numerical analysis of banding patterns. AFLP type was defined on the basis of 100% similarity in the dendrogram obtained, yielding 24 distinct AFLP profiles. At 70% similarity, 13 clusters were defined, thus confirming the great variability observed for the phenotypic traits. Conclusions: The AFLP variability shown by the isolates was high enough to discriminate between different strains which colonize the same fish. However, closely related AFLP types were usually derived from strains isolated at the same fish farm, indicating an epidemiological relationship. Significance and Impact of the Study: This study has confirmed that the AFLP technique allows discrimination of individual strains within P. damselae subsp. damselae for epidemiological studies, and that this subspecies exhibits greater variability than that described for subspecies piscicida. [source] RESEARCH INTO PAIN PERCEPTION WITH ARTERIOVENOUS FISTULA (AVF) CANNULATIONJOURNAL OF RENAL CARE, Issue 4 2008Ana E. Figueiredo RN SUMMARY Patients with end-stage renal failure (ESRF) undergoing haemodialysis (HD) are repeatedly exposed to stress and pain from approximately 300 punctures per year to their arteriovenous fistula (AVF). Repeated AVF punctures lead to a considerable degree of pain, due to the calibre and length of the bevel of fistula needles. Pain is a sensitive, emotional and subjective experience. The objective of this study was to measure pain associated with AVF needling. The analogue visual scale (AVS) divided into 10 equal parts (0 indicating lack of pain, and 10 unbearable pain) was used. Patients7 perceptions were measured in three different HD sessions. Pain was considered mild during AVF needling. The buttonhole technique caused a mean degree of pain of 2.4 (±1.7), compared to 3.1 (±2.3) using the conventional ropeladder technique. Although without reaching a statistically significant difference, diminished pain was associated with the buttonhole technique. [source] In search of well-started beginning science teachers: Insights from two first-year elementary teachersJOURNAL OF RESEARCH IN SCIENCE TEACHING, Issue 6 2010Lucy Avraamidou Abstract The purpose of this qualitative case study was to explore what aspects of two first-year elementary teachers' practices were most consistent with an inquiry-based approach, what PCK served as a mechanism for facilitating these practices, and what experiences have mediated the nature and development of these teachers' PCK. For each of the participants data included audio-recorded interviews, video-recorded classroom observations, lesson plans, and samples of student work. Data analysis illustrated that both participants engaged their students in question-driven investigations, the use of observational data, making connections between evidence and claims, and communicating those claims to others. Moreover, there was clear evidence in the findings of the study that a considerable degree of coherence existed between the two participants' knowledge on one hand and their instructional practices on the other hand. The participants perceived specific learning experiences during their programs as being critical to their development. The contribution of this study lies in the fact that it provides examples of well-started beginning elementary teachers implementing inquiry-based science in 2nd and 5th grade classrooms. Implications of the study include the need for the design of university-based courses and interventions by which teacher preparation and professional development programs support teachers in developing PCK for scientific inquiry and enacting instructional practices that are congruent with reform initiatives. © 2010 Wiley Periodicals, Inc. J Res Sci Teach 47:661,686, 2010 [source] Gaeumannomyces graminis, the take-all fungus and its relativesMOLECULAR PLANT PATHOLOGY, Issue 4 2004JACQUELINE FREEMAN SUMMARY Take-all, caused by the fungus Gaeumannomyces graminis var. tritici, is the most important root disease of wheat worldwide. Many years of intensive research, reflected by the large volume of literature on take-all, has led to a considerable degree of understanding of many aspects of the disease. However, effective and economic control of the disease remains difficult. The application of molecular techniques to study G. graminis and related fungi has resulted in some significant advances, particularly in the development of improved methods for identification and in elucidating the role of the enzyme avenacinase as a pathogenicity determinant in the closely related oat take-all fungus (G. graminis var. avenae). Some progress in identifying other factors that may be involved in determining host range and pathogenicity has been made, despite the difficulties of performing genetic analyses and the lack of a reliable transformation system. [source] Density gradients in Galactic planetary nebulaeMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2007J. P. Phillips ABSTRACT Certain hydrodynamic models of planetary nebulae (PNe) suggest that their shells possess appreciable radial density gradients. However, the observational evidence for such gradients is far from clear. On the one hand, Taylor et al. claim to find evidence for radio spectral indices 0.6 < , < 1.8, a trend which is taken to imply a variation ne,r,2 in most of their sample of PNe. On the other hand, Siódmiak & Tylenda find no evidence for any such variations in density; shell inhomogeneities, where they occur, are primarily attributable to ,blobs or condensations'. It will be suggested that both of these analyses are unreliable, and should be treated with a considerable degree of caution. A new analysis within the log(F(5 GHz)/F(1.4 GHz)),log(TB(5 GHz)) plane will be used to show that at least 10,20 per cent of PNe are associated with strong density gradients. We shall also show that the ratio F(5 GHz)/F(1.4 GHz) varies with nebular radius; an evolution that can be interpreted in terms of varying shell masses, and declining electron densities. [source] Voters, Parties, and the Endogenous Size of GovernmentAMERICAN JOURNAL OF ECONOMICS AND SOCIOLOGY, Issue 1 2002Jans-Peter Olters Elections, often to a considerable degree, influence the fiscal policies of governments installed on the basis of their results. Yet, economists have tended to view politicians' behaviour either as being determined exogenously or as the result of a social planner's maximisation of a well-defined social-welfare function (subject to some appropriate technology and resource constraints). The latter approach, given (i) its inherent abstraction from important politico-economic interactions, (ii) the theoretical difficulty in deriving a non-contradictory "collective utility function" (as demonstrated by Arrow), and (iii) the inability to estimate a stable relationship that could explain political preferences with economic variables,is viewed as being an unsatisfactory tool for the joint description of a country's economy and polity. On the basis of explicit micro-economic foundations and a democratically coordinated decision-making mechanism over the "optimal" provision of public goods and the corresponding taxes required to finance them, this paper will introduce a simple economic model of politics that subjects individuals to a,two-tiered,political decision-making process over party membership and electoral participation, thereby endogenising the evolution of the competing parties' ideologies, households' electoral behaviour, and the key factors explaining the design of fiscal policies. Having the majority party's median delegate determine on the "optimal" degree of income redistribution suggests that a country's wealth distribution is a crucial explanatory variable explaining its politico-economic development path. [source] Auricular surface aging: Worse than expected?AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2006A test of the revised method on a documented historic skeletal assemblage Abstract This study presents results and recommendations arising from a blind test of the revised age estimation method for the auricular surface as proposed by Buckberry and Chamberlain (2002 Am. J. Phys. Anthropol. 119:321,329). Auricular surfaces of 167 individuals from St. Bride's, London, a documented skeletal assemblage spanning the late 17th to early 19th century, were analyzed for the following traits: transverse organization, surface texture appearance, macroporosity, microporosity, and morphological changes to the apex. Composite scores of trait expressions were found to generally correlate with age and to show a positive association with known chronological age (P < 0.01). However, when composite scores were combined to define auricular surface phases, which ultimately assign age estimations, only three distinct developmental stages, compared with seven suggested by Buckberry and Chamberlain (2002 Am. J. Phys. Anthropol. 119:321,329), could be identified and statistically supported, all showing a considerable degree of individual variation in age. The most well-defined stage in the St. Bride's assemblage was the new stage III, where the majority of individuals were older than 60 years, whereas middle-aged adults displayed a large variation in composite scores. These results provide little hope for a promising application of age-at-death estimation of auricular surface morphology traits with higher resolution, but rather suggest indications of broad stages of life. Am J Phys Anthropol, 2006. © 2006 Wiley-Liss, Inc. [source] Does Truth Lead to Reconciliation?AMERICAN JOURNAL OF POLITICAL SCIENCE, Issue 2 2004Reconciliation Process, Testing the Causal Assumptions of the South African Truth Throughout the world, truth commissions have been created under the assumption that getting people to understand the past will somehow contribute to reconciliation between those who were enemies under the ancien regime. In South Africa, the truth and reconciliation process is explicitly based on the hypothesis that knowledge of the past will lead to acceptance, tolerance, and reconciliation in the future. My purpose here is to test that hypothesis, based on data collected in a 2001 survey of over 3,700 South Africans. My most important finding is that those who accept the "truth" about the country's apartheid past are more likely to hold reconciled racial attitudes. Racial reconciliation also depends to a considerable degree on interracial contact, evidence that adds weight to the "contact hypothesis" investigated by western social scientists. Ultimately, these findings are hopeful for South Africa's democratic transition, since racial attitudes seem not to be intransigent. [source] Perceptual considerations in the use of colored photographic and video stimuli to study nonhuman primate behaviorAMERICAN JOURNAL OF PRIMATOLOGY, Issue 11 2006Corri Waitt Abstract The use of photographs, slides, computerized images, and video to study behavior is increasingly being employed in nonhuman primates. However, since these mediums have been designed to simulate natural coloration for normal trichromatic human vision, they can fail to reproduce color in meaningful and accurate ways for viewers with different visual systems. Given the range of color perception that exists both across and within different species, it is necessary to consider this variation in order to discern the suitability of these mediums for experimental use. Because of the high degree of visual similarity among humans, Old World monkeys, and apes, the use of photographic and video stimuli should be acceptable in terms of replicating naturalistic coloration and making noticeable color manipulations. However, among New World primates and prosimians, there exists a considerable degree of variation in color perceptual abilities depending on the species, sex, and allelic combination of the animals involved. Therefore, the use of these mediums to study behavior is problematic for these species, and should be done with caution. Am. J. Primatol. 68:1054,1067, 2006. © 2006 Wiley-Liss, Inc. [source] Structures of three diphtheria toxin repressor (DtxR) variants with decreased repressor activityACTA CRYSTALLOGRAPHICA SECTION D, Issue 5 2001Ehmke Pohl The diphtheria toxin repressor (DtxR) from Corynebacterium diphtheriae regulates the expression of the gene on corynebacteriophages that encodes diphtheria toxin (DT). Other genes regulated by DtxR include those that encode proteins involved in siderophore-mediated iron uptake. DtxR requires activation by divalent metals and holo-DtxR is a dimeric regulator with two distinct metal-binding sites per three-domain monomer. At site 1, three side chains and a sulfate or phosphate anion are involved in metal coordination. In the DtxR,DNA complex this anion is replaced by the side chain of Glu170 provided by the third domain of the repressor. At site 2 the metal ion is coordinated exclusively by constituents of the polypeptide chain. In this paper, five crystal structures of three DtxR variants focusing on residues Glu20, Arg80 and Cys102 are reported. The resolution of these structures ranges from 2.3 to 2.8,Å. The side chain of Glu20 provided by the DNA-binding domain forms a salt bridge to Arg80, which in turn interacts with the anion. Replacing either of the salt-bridge partners with an alanine reduces repressor activity substantially and it has been inferred that the salt bridge could possibly control the wedge angle between the DNA-binding domain and the dimerization domain, thereby modulating repressor activity. Cys102 is a key residue of metal site 2 and its substitution into a serine abolishes repressor activity. The crystal structures of Zn-Glu20Ala-DtxR, Zn-Arg80Ala-DtxR, Cd-Cys102Ser-DtxR and apo-Cys102Ser-DtxR in two related space groups reveal that none of these substitutions leads to dramatic rearrangements of the DtxR fold. However, the five crystal structures presented here show significant local changes and a considerable degree of flexibility of the DNA-binding domain with respect to the dimerization domain. Furthermore, all five structures deviate significantly from the structure in the DtxR,DNA complex with respect to overall domain orientation. These results confirm the importance of the hinge motion for repressor activity. Since the third domain has often been invisible in previous crystal structures of DtxR, it is also noteworthy that the SH3-like domain could be traced in four of the five crystal structures. [source] Electronic Properties of Propylamine-Functionalized Single-Walled Carbon NanotubesCHEMPHYSCHEM, Issue 11 2010Matthias Müller Abstract We present resonant Raman measurements on single-walled carbon nanotubes (SWCNT) functionalized with propylamine groups at different degrees. Direct nucleophilic addition based on in situ generated primary amides is used for attaching n -propylamine to the sidewalls of SWCNTs. The influence of the amino functionalities on the electronic structure of the nanotubes is investigated. From the Raman resonance profiles of the radial breathing modes (RBMs), the chiral indices of the corresponding tubes are assigned. We observe significant redshifts of the transition energies and a broadening of the resonance windows due to chemical modification of SWCNTs. Similar redshifts are derived from the analysis of the NIR/Vis transmission spectrum. The relative Raman intensities of the functionalized samples and the evaluation of their transmission spectra indicate a diameter dependence of the reactivity as it has been observed for other moieties. By analyzing the defect induced D mode we observe a considerable degree of functionalization accompanied by an almost unharmed tube structure, which ensures that the observed effects are mainly driven by changes of the electronic structure. [source] Psychiatric treatments in dermatology: an updateCLINICAL & EXPERIMENTAL DERMATOLOGY, Issue 2 2010R. Sambhi Summary There is a considerable degree of connection between psychiatry and dermatology. This connection is relevant both for diagnosis and management of dermatological pathology. This article summarises common psychiatric conditions seen in patients with skin disease, both primary psychiatric disorders and psychiatric disorders secondary to dermatological pathology. Diagnosis of relevant psychiatric conditions such as anxiety, depression, obsessive,compulsive disorder, delusional parasitosis and dermatitis artefacta, and psychiatric treatments are discussed. It gives an update of psychopharmacology relevant to the dermatologist including important interactions between psychotropic and dermatological agents. [source] | ||||||||||||||||||||||