Home About us Contact
|
Home About us Contact | ||
|
|
||
Complex
Kinds of Complex Terms modified by Complex Selected AbstractsEDITORS' INTRODUCTION TO THE "COKE COMPLEX"CULTURAL ANTHROPOLOGY, Issue 4 2007KIM FORTUN First page of article [source] RAPID ADAPTIVE DIVERGENCE IN NEW WORLD ACHILLEA, AN AUTOPOLYPLOID COMPLEX OF ECOLOGICAL RACESEVOLUTION, Issue 3 2008Justin Ramsey Adaptive evolution is often associated with speciation. In plants, however, ecotypic differentiation is common within widespread species, suggesting that climatic and edaphic specialization can outpace cladogenesis and the evolution of postzygotic reproductive isolation. We used cpDNA sequence (5 noncoding regions, 3.5 kb) and amplified fragment length polymorphisms (AFLPs: 4 primer pairs, 1013 loci) to evaluate the history of ecological differentiation in the North American Achillea millefolium, an autopolyploid complex of "ecological races" exhibiting morphological, physiological, and life-history adaptations to diverse environments. Phylogenetic analyses reveal North American A. millefolium to be a monophyletic group distinct from its European and Asian relatives. Based on patterns of sequence divergence, as well as fossil and paleoecological data, colonization of North America appears to have occurred via the Bering Land Bridge during the Pleistocene (1.8 MYA to 11,500 years ago). Population genetic analyses indicate negligible structure within North American A. millefolium associated with varietal identity, geographic distribution, or ploidy level. North American populations, moreover, exhibit the signature of demographic expansion. These results affirm the "ecotype" concept of the North American Achillea advocated by classical research and demonstrate the rapid rate of ecological differentiation that sometimes occurs in plants. [source] EVOLUTION OF REPRODUCTIVE ISOLATION WITHIN A PARASITIC FUNGAL SPECIES COMPLEXEVOLUTION, Issue 7 2007Mickael Le Gac Despite important advances in the last few years, the evolution of reproductive isolation (RI) remains an unresolved and critical gap in our understanding of speciation processes. In this study, we investigated the evolution of RI among species of the parasitic fungal species complex Microbotryum violaceum, which is responsible for anther smut disease of the Caryophyllaceae. We found no evidence for significant positive assortative mating by M. violaceum even over substantial degrees of genetic divergence, suggesting a lack of prezygotic isolation. In contrast, postzygotic isolation increased with the genetic distance between mating partners when measured as hyphal growth. Total RI, measured as the ability of the pathogen to infect and produce a diploid progeny in the host plant, was significantly and positively correlated with genetic distance, remaining below complete isolation for most of the species pairs. The results of this study, the first one on the time course of speciation in a fungus, are therefore consistent with previous works showing that RI generally evolves gradually with genetic distance, and thus presumably with time. Interestingly, prezygotic RI due to gamete recognition did not increase with genetic distance, in contrast to the pattern found in plants and animals. [source] BALANCING SELECTION, RANDOM GENETIC DRIFT, AND GENETIC VARIATION AT THE MAJOR HISTOCOMPATIBILITY COMPLEX IN TWO WILD POPULATIONS OF GUPPIES (POECILIA RETICULATA)EVOLUTION, Issue 12 2006Cock van Oosterhout Abstract Our understanding of the evolution of genes of the major histocompatibility complex (MHC) is rapidly increasing, but there are still enigmatic questions remaining, particularly regarding the maintenance of high levels of MHC polymorphisms in small, isolated populations. Here, we analyze the genetic variation at eight microsatellite loci and sequence variation at exon 2 of the MHC class IIB (DAB) genes in two wild populations of the Trinidadian guppy, Poecilia reticulata. We compare the genetic variation of a small (Ne, 100) and relatively isolated upland population to that of its much larger (Ne, 2400) downstream counterpart. As predicted, microsatellite diversity in the upland population is significantly lower and highly differentiated from the population further downstream. Surprisingly, however, these guppy populations are not differentiated by MHC genetic variation and show very similar levels of allelic richness. Computer simulations indicate that the observed level of genetic variation can be maintained with overdominant selection acting at three DAB loci. The selection coefficients differ dramatically between the upland (s 0.2) and lowland (s, 0.01) populations. Parasitological analysis on wild-caught fish shows that parasite load is significantly higher on upland than on lowland fish, which suggests that large differences in selection intensity may indeed exist between populations. Based on the infection intensity, a substantial proportion of the upland fish would have suffered direct or indirect fitness consequences as a result of their high parasite loads. Selection by parasites plays a particularly important role in the evolution of guppies in the upland habitat, which has resulted in high levels of MHC diversity being maintained in this population despite considerable genetic drift. [source] SEXUAL PROCESSES AND PHYLOGENETIC RELATIONSHIPS OF A HOMOTHALLIC STRAIN IN THE CLOSTERIUM PERACEROSUM,STRIGOSUM,LITTORALE COMPLEX (ZYGNEMATALES, CHAROPHYCEAE),JOURNAL OF PHYCOLOGY, Issue 2 2010Yuki Tsuchikane Members of the Closterium peracerosum,strigosum,littorale (C. psl.) complex are unicellular charophycean algae in which there are two modes of zygospore formation, heterothallic and homothallic. A homothallic strain of Closterium (designation, kodama20) was isolated from a Japanese rice paddy field. Based on alignment of the 1506 group-I introns, which interrupt nuclear SSU rDNAs, homothallic kodama20 is most closely related to the heterothallic mating group II-B, which is partially sexually isolated from group II-A. Time-lapse photography of the conjugation process in kodama20 revealed that most of the observed zygospores originated from one vegetative cell. The sexual conjugation process consisted of five stages: (1) cell division resulting in the formation of two sister gametangial cells from one vegetative cell, (2) formation of a sexual pair between the two sister gametangial cells (or between gametangial cells of another adjoined individual), (3) formation of conjugation papillae, (4) release of gametic protoplasts from both members of a pair, and (5) formation of the zygospore by protoplast fusion. For conjugation to progress, the cell density and light condition in the culture was critical. We suggested the presence of a conjugation promotion factor. [source] REPRODUCTIVE ISOLATION BY SEX PHEROMONES IN THE CLOSTERIUM PERACEROSUM,STRIGOSUM,LITTORALE COMPLEX (ZYGNEMATALES, CHAROPHYCEAE),JOURNAL OF PHYCOLOGY, Issue 5 2008Yuki Tsuchikane The Closterium peracerosum,strigosum,littorale (C. psl.) complex consists of unicellular algae and is known to be composed of several reproductively isolated mating groups of heterothallic strains. Group I-E is completely isolated from mating groups II-A and II-B, groups II-A and II-B are partially isolated from each other, and only mating-type plus (mt+) cells of group II-A and mating-type minus (mt,) cells of group II-B form zygotes. Based on the alignment of 1506 group I introns, significant phylogenetic relationships were observed among mating groups II-A and II-B, while mating group I-E was distant from groups II-A and II-B. Sexual cell division in both mating-type cells of group II-A was stimulated in conditioned media in which cells of group II-B had been cultured. When mt, cells of group II-B were stimulated in conditioned medium derived from group II-A, mt+ cells of group II-B did not respond to the conditioned medium. Conditioned media derived from group I-E did not exhibit sexual cell division (SCD),inducing activity against any strain except those within its own group. From the alignment of deduced amino acid sequences from orthologous protoplast-release-inducing protein (PR-IP) Inducer genes, we detected a significant similarity among groups II-A and II-B, and mating group I-E had low similarity to other mating groups. The existing degree of reproductive isolation can be partially explained by differences in molecular structures and physiological activities of sex pheromones of these heterothallic mating groups. [source] INTER- AND INTRASPECIFIC VARIATION OF THE PSEUDO-NITZSCHIA DELICATISSIMA COMPLEX (BACILLARIOPHYCEAE) ILLUSTRATED BY RRNA PROBES, MORPHOLOGICAL DATA AND PHYLOGENETIC ANALYSES,JOURNAL OF PHYCOLOGY, Issue 2 2006Nina Lundholm A study of 25 cultures tentatively identified as Pseudo-nitzschia delicatissima (Cleve) Heiden, and originating from geographically widely distributed locations, showed both morphological and genetic variation among strains. Use of rRNA-targeted DNA probes on 17 different strains showed large variation in the hybridization patterns. Detailed morphological studies placed the isolates into three groups. The sample on which the neotype of P. delicatissima is based was also examined, and used to establish the morphological identity of P. delicatissima. Phylogenetic analyses of 16 strains, based on sequences of internal transcriber spacer 1 (ITS1), 5.8S and ITS2 of the nuclear-encoded rDNA, supported the morphological observations and the hybridization studies, and revealed large genetic variation among strains. A combination of the morphological and molecular findings resulted in the description of two new species, P. decipiens sp. nov. and P. dolorosa sp. nov. P. dolorosa has a mixture of one or two rows of poroids in the striae whereas P. delicatissima always has two rows. In addition, P. dolorosa has wider valves and a lower density of poroids. P. decipiens differs from P. delicatissima by a higher density of striae on the valve face as well as a higher density of poroids on the girdle bands. Among the strains referred to P. delicatissima, an epitype was selected. Large genetic variation was found among the P. delicatissima strains and a subdivision into two major clades represent cryptic species. [source] DIATOMS: A COMPLEX EVOLUTIONARY HISTORY BECOMES EVEN MORE COMPLEXJOURNAL OF PHYCOLOGY, Issue 1 2003Klaus V. Kowallik No abstract is available for this article. [source] MOLECULAR AND MORPHOLOGICAL DATA IDENTIFY A CRYPTIC SPECIES COMPLEX IN ENDOPHYTIC MEMBERS OF THE GENUS COLEOCHAETE BRÉB. (CHAROPHYTA: COLEOCHAETACEAE),JOURNAL OF PHYCOLOGY, Issue 6 2002Matthew T. Cimino The genus Coleochaete Bréb. is a relatively small group of freshwater microscopic green algae with about 15 recognized species. Although Coleochaete has long been considered to be a close relative of embryophytes, a comprehensive study of the genus has not been published since Pringsheim's 1860 monograph. As part of a systematic study of Coleochaete, we investigated four accessions of the genus that are morphologically similar to the endophytic species C. nitellarum Jost. Each of the four cultures was determined to be capable of endophytic growth in Nitella C. A. Agardh, a member of the closely related order Charales. Maximum likelihood and maximum parsimony analyses were performed on nucleotide data from the chloroplast genes atpB and rbcL that were sequenced from 16 members of the Coleochaetales and from other members of the Charophyceae, embryophytes, and outgroup taxa. These analyses indicate that the Coleochaetales are monophyletic and that the endophytic accessions are members of the scutata group of species. In addition, cell size and nucleotide data suggest that at least three different endophytic species may be represented. Herbivory, nutritional benefits, and substrate competition are three hypotheses that could explain the evolution and maintenance of the endophytic habit in Coleochaete. These data also imply that diversity in the genus may be markedly underestimated. [source] ULTRASTRUCTURE OF THE BASAL BODY COMPLEX AND PUTATIVE VESTIGIAL FEEDING APPARATUS IN PHACUS PLEURONECTES (EUGLENOPHYCEAE)JOURNAL OF PHYCOLOGY, Issue 2001Article first published online: 24 SEP 200 Shin, W.1, Boo, S. M.2, & Triemer, R. E.1 1Department of Life Science, Rutgers University, Piscataway, New Jersey 08854, USA; 2Department of Biology, Chungnam National University, Daejon 305-764, Korea Phacus pleuronectes (O. F. Müller) Dujardin is a phototrophic euglenoid with small discoid chloroplasts, a flat, rigid body, and longitudinally arranged pellicular strips. The flagellar apparatus consisted of two basal bodies and three flagellar roots typical of many phototrophic euglenoids, but also had a large striated fiber that connected the two basal bodies and associated with the ventral root. The three roots, in combination with the dorsal microtubular band, extended anteriorly and formed the major cytoskeletal elements supporting the reservoir membrane and ultimately the pellicle. A cytoplasmic pocket arose in the reservoir/canal transition region. It was supported by the ventral root and a C-shaped band of electron-opaque material that lined the cytoplasmic side of the pocket. A large striated fiber extended from this C-shaped band toward the reservoir membrane. The presence of striated fibers in the basal apparatus and associated with the microtubule reinforced pocket suggested that P. pleuronectes may be at the base of the Phacus lineage and may be more closely related to the phagotrophic euglenoids than to Phacus species which are ovoid in shape and have thicker pellicle strips. [source] ANALYSIS OF NASRID POLYCHROME CARPENTRY AT THE HALL OF THE MEXUAR PALACE, ALHAMBRA COMPLEX (GRANADA, SPAIN), COMBINING MICROSCOPIC, CHROMATOGRAPHIC AND SPECTROSCOPIC METHODS,ARCHAEOMETRY, Issue 4 2009C. CARDELL The pigments, binders and execution techniques used by the Nasrids (1238,1492) to polychrome carpentry in the Hall of the Mexuar Palace at the Alhambra (Granada, Spain) were studied using optical microscopy, scanning electron microscopy with EDX analysis, selective staining techniques and gas chromatography , mass spectrometry. This pioneering investigation presents the first results of a research project devoted to filling gaps in the knowledge of Nasrid art, traditionally approached by stylistic studies. Moreover, it is essential for the polychromy conservation of the studied artworks, and will help to clarify historical and painting uncertainties in the Alhambra monument. The palette consists of a limited range of colours: white (lead-base pigment), red (cinnabar and red lead), blue (lapis lazuli), black (carbon-based) and false gold (golden tin). Tempera grassa was the painting technique identified. Two types of grounds were used: (i) gypsum in calligraphy decoration for the false gold technique, and (ii) synthetic minium in geometric drawings in carpentry. Organic insulating layers of linseed oil were used between paint strata. Artists applied synthetic minium to protect the wood (Juglans regia and conifer) against attack by xylophages. To lighten the surface darkened by this ground layer, powdered tin was added to achieve a metallic lustre. [source] EFFECT OF BAY 41-2272 IN THE PULMONARY HYPERTENSION INDUCED BY HEPARIN,PROTAMINE COMPLEX IN ANAESTHETIZED DOGSCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 1-2 2007Cristiane F Freitas SUMMARY 1BAY 41-2272 is a potent activator of the nitric oxide-independent site of soluble guanylate cyclase and has been recently introduced as a new therapeutic agent to treat chronic pulmonary hypertension (PH) in neonatal sheep. Because the in vivo heparin,protamine interaction may lead to severe PH, the aim of the present study was to evaluate the effects of BAY 41-2272 in the PH induced by heparin,protamine interaction in anaesthetized dogs. 2Sixteen male dogs (10 mongrel dogs and six Beagles) were anaesthetized and instrumented for acquisition of mean arterial blood pressure (MABP), mean pulmonary arterial pressure (MPAP), heart rate (HR), pulmonary capillary wedge pressure (PCWP), cardiac index (CI) and indices of systemic and pulmonary vascular resistance (ISVR and IPVR, respectively). Plasma cGMP levels and Spo2 were evaluated. 3Intravenous administration of heparin (500 IU/kg) followed 3 min later by protamine (10 mg/kg) caused marked PH, as evaluated by the increase in MPAP, PCWP and IPVR. This was accompanied by a significant fall in MABP and a transient increase in HR. Infusion of BAY 41-2272 (10 µg/kg per h, starting 10 min before heparin administration) augmented plasma cGMP levels and slightly and significantly increased HR and CI, without affecting the other cardiovascular parameters. The elevation in IPVR, MPAP and PCWP triggered by the heparin,protamine interaction was significantly reduced in animals exposed to BAY 41-2272. 4In vehicle-treated dogs, the Spo2 values decreased significantly at the peak of the PH and this was significantly attenuated by treatment with BAY 41-2272. In addition, BAY 41-2272 (10 µmol/L) had no effect on the activated partial thromboplastin time of citrated plasma after the addition of heparin,protamine. 5In conclusion, BAY 41-2272 was effective in reducing canine PH induced in vivo by the heparin,protamine interaction, thus indicating its potential in the treatment of this type of disorder. [source] A Data-driven Segmentation for the Shoulder ComplexCOMPUTER GRAPHICS FORUM, Issue 2 2010Q Youn Hong Abstract The human shoulder complex is perhaps the most complicated joint in the human body being comprised of a set of three bones, muscles, tendons, and ligaments. Despite this anatomical complexity, computer graphics models for motion capture most often represent this joint as a simple ball and socket. In this paper, we present a method to determine a shoulder skeletal model that, when combined with standard skinning algorithms, generates a more visually pleasing animation that is a closer approximation to the actual skin deformations of the human body. We use a data-driven approach and collect ground truth skin deformation data with an optical motion capture system with a large number of markers (200 markers on the shoulder complex alone). We cluster these markers during movement sequences and discover that adding one extra joint around the shoulder improves the resulting animation qualitatively and quantitatively yielding a marker set of approximately 70 markers for the complete skeleton. We demonstrate the effectiveness of our skeletal model by comparing it with ground truth data as well as with recorded video. We show its practicality by integrating it with the conventional rendering/animation pipeline. [source] Manifold Homotopy via the Flow ComplexCOMPUTER GRAPHICS FORUM, Issue 5 2009Bardia Sadri Abstract It is known that the critical points of the distance function induced by a dense sample P of a submanifold , of ,n are distributed into two groups, one lying close to , itself, called the shallow, and the other close to medial axis of ,, called deep critical points. We prove that under (uniform) sampling assumption, the union of stable manifolds of the shallow critical points have the same homotopy type as , itself and the union of the stable manifolds of the deep critical points have the homotopy type of the complement of ,. The separation of critical points under uniform sampling entails a separation in terms of distance of critical points to the sample. This means that if a given sample is dense enough with respect to two or more submanifolds of ,n, the homotopy types of all such submanifolds together with those of their complements are captured as unions of stable manifolds of shallow versus those of deep critical points, in a filtration of the flow complex based on the distance of critical points to the sample. This results in an algorithm for homotopic manifold reconstruction when the target dimension is unknown. [source] The Role of Natriuretic Peptides in Patients With Chronic Complex (Mixed or Multiple) Heart Valve DiseaseCONGESTIVE HEART FAILURE, Issue 2 2010FRACP, Naylin Bissessor MBChB N-terminal prohormone B-type natriuretic peptide (NT-proBNP) is an important biomarker of prognosis in heart failure and single valve disease. There are limited studies of complex valve disease. Patients with complex valve disease adopt a sedentary lifestyle, so symptoms may be difficult to detect. The authors aimed to determine whether NT-proBNP correlates with the severity of the valve lesion and underlying cardiac function and whether resting NT-proBNP predicts impaired peak VO2 in patients with complex valve disease. Forty-five patients with complex moderate to severe stenosis or regurgitation of the heart valves underwent a clinical assessment, echocardiography, resting NT-proBNP assessment, and formal cardiopulmonary exercise testing. In a multivariate analysis, the log NT-proBNP (,=,9.3, SE=1.9, P<.0001) and lean body weight (,=0.59, SE=0.22, P=.01) were dominant independent predictors of peak VO2. An NT-proBNP value of 84 pmol/L had 77% sensitivity and 70% specificity to predict impaired functional capacity, peak VO2 <60% (predicted), area under the curve=0.80. Resting NT-proBNP was the best predictor of peak VO2 in patients with complex valve disease, while symptoms and ejection fraction are a less reliable guide. Congest Heart Fail. 2010;16:50,54. © 2009 Wiley Periodicals, Inc. [source] Synthesis and structure of a new one-dimensional cobalt complex with dicyanamide and 4-picolyl choride bridgesCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2006Hongxia Pei Abstract The synthesis and structure of the 1D cobalt (II) complex, [Co(L)2(dca)2] (1) (dca = dicyanamide, C2N3,, L = 4-picolyl choride) is reported. Complex 1 crystallized in triclinic system, space group P -1, with cell dimensions of a = 7.291(2) Å, b = 7.481(2) Å, c = 9.007(3) Å, , =104.444(4)°, , = 96.971(4)°, , =102.618(4)°, V = 456.1(2) Å3, Z = 1, Dc = 1.624 Mg/m3. In complex 1, Co (II) is 6-coordinated by N atoms of four dca ligands and two L ligands. The centrosymmetric CoN6 chromophore is an axially elongated octahedron that has Co-N distances ranging from 2.122(3) to 2.154(3) Å. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Remodeling of the actin cytoskeleton of target hepatocytes and NK cells during induction of apoptosisCYTOSKELETON, Issue 2 2001W. Marty Blom Abstract Natural Killer cells are immune cells that recognize and eliminate altered and non-self cells from the circulation. To study the interaction between NK cells and target cells, we set up an experimental system consisting of rat Interleukin-2 activated Natural Killer cells (A-NK cells) and rat hepatocytes with a masked Major Histocompatibility Complex (MHC). The masking of the MHC induces recognition of the hepatocytes by the NK cells as non-self. We showed that in vitro apoptosis is rapidly induced in the hepatocytes [Blom et al., 1999] after co-incubation with A-NK cells. Now we describe the morphological changes that occur during and after interaction of A-NK cells with hepatocytes. Confocal laser scanning microscopy showed that the actin cytoskeleton of the NK cells was remodeled during attack of hepatocytes. Some NK cells were in close contact with the hepatocytes while others had formed actin-containing dendrites of varying length that made contact with the hepatocytes. However, dendrite formation is not obligatory for induction of apoptosis because cells that were unable to form these did induce FAS-dependent apoptosis in hepatocytes. Apparently both direct as well as distant contact resulted in apoptosis. Formation of the dendrites was calcium-dependent as EGTA largely prevented it. Importantly, chelation of the calcium also suppressed killing of the hepatocytes. Within 1 h after addition of the A-NK cells, morphological changes in hepatocytes that are characteristic of apoptosis, such as the formation of apoptotic bodies and fragmented nuclei, became apparent. Specifically, the actin cytoskeleton of the hepatocytes was remodeled resulting in the formation of the apoptotic bodies. Inhibition of caspase activity by z-Val-Ala-DL-Asp-fluoromethylketone (100 ,M) partly protected against the rearrangement of the actin filaments in the hepatocytes. Cell Motil. Cytoskeleton 49:78,92, 2001. © 2001 Wiley-Liss, Inc. [source] Cosmetic Color Improvement of the Nipple-Areola Complex by Optimal Use of Tretinoin and HydroquinoneDERMATOLOGIC SURGERY, Issue 12 2002Kotaro Yoshimura MD background. A successful treatment to improve the color of nipple-areola complex (NAC) has never been reported, although the number of women seeking the more attractively colored NAC is not small. objective. To determine the effectiveness of our bleaching protocol for cosmetic improvement of the NAC. methods. The protocol was composed of two phases: bleaching phase (4,8 weeks) and healing phase (4,6 weeks). 0.2,0.4% tretinoin aqueous gel was applied concomitantly with 5% hydroquinone, 7% lactic acid ointment for bleaching twice a day. Tretinoin was applied to the NAC with a small cotton applicator, while hydroquinone was widely applied beyond the NAC area. After obtaining sufficient improvement in NAC color, the application of tretinoin was discontinued and hydroquinone alone was continually applied in the healing phase until the reactive erythema was eliminated. Fifteen female patients were involved in this study. results. The average treatment period was 16.6 weeks. Improvement of NAC color was obtained in 12 patients (80%) by the physician's estimation, and 11 patients (73%) satisfied with their final results. The treatment was repeated after a 1-month interval of tretinoin application in 4 patients: 2 desired further improvement in color, and 2 had the second course conducted to treat the postinflammatory hyperpigmentation on the surrounding mound induced by the first course. conclusion. This approach appeared to be most effective for cosmetic improvement of NAC color among treatments available so far. [source] E2f6 and Bmi1 cooperate in axial skeletal developmentDEVELOPMENTAL DYNAMICS, Issue 5 2008Maria Courel Abstract Bmi1 is a Polycomb Group protein that functions as a component of Polycomb Repressive Complex 1 (PRC1) to control axial skeleton development through Hox gene repression. Bmi1 also represses transcription of the Ink4a-Arf locus and is consequently required to maintain the proliferative and self-renewal properties of hematopoietic and neural stem cells. Previously, one E2F family member, E2F6, has been shown to interact with Bmi1 and other known PRC1 components. However, the biological relevance of this interaction is unknown. In this study, we use mouse models to investigate the interplay between E2F6 and Bmi1. This analysis shows that E2f6 and Bmi1 cooperate in the regulation of Hox genes, and consequently axial skeleton development, but not in the repression of the Ink4a-Arf locus. These findings underscore the significance of the E2F6,Bmi1 interaction in vivo and suggest that the Hox and Ink4a-Arf loci are regulated by somewhat different mechanisms. Developmental Dynamics 237:1232-1242, 2008. © 2008 Wiley-Liss, Inc. [source] Intermediate metabolism in normal pregnancy and in gestational diabetesDIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 4 2003G. Di Cianni Abstract Complex though integrated hormonal and metabolic changes characterize pregnancy. In the face of progressive decline in insulin action, glucose homeostasis is maintained through a compensatory increase in insulin secretion. This switches energy production from carbohydrates to lipids, making glucose readily available to the fetus. This precise and entangled hormonal and metabolic condition can, however, be disrupted and diabetic hyperglycemia can develop (gestational diabetes). The increase in plasma glucose level is believed to confer significant risk of complications to both the mother and the fetus and the newborn. Moreover, exposition of fetal tissues to the diabetic maternal environment can translate into an increased risk for development of diabetes and/or the metabolic syndrome in the adult life. In women with previous gestational diabetes, the risk of developing type 2 diabetes is greatly enhanced, to the point that GDM represents an early stage in the natural history of type 2 diabetes. In these women, accurate follow-up and prevention strategies are needed to reduce the subsequent development of overt diabetes. This paper will review current knowledge on the modifications occurring in normal pregnancy, while outlining the mechanisms. In this paper, we will review the changes of intermediary metabolism occurring during pregnancy. In particular, we will outline the mechanisms responsible for gestational diabetes; the link between these alterations and associated maternal and neonatal morbidity will be examined. Copyright © 2003 John Wiley & Sons, Ltd. [source] Randomized controlled trials in schizophrenia: a critical perspective on the literatureACTA PSYCHIATRICA SCANDINAVICA, Issue 4 2002S. Gilbody Objective:,The randomized trial provides an opportunity to minimize the inclusion of biases in the evaluation of interventions in psychiatry. Difficulties arise, however, when applying their results to `real world' clinical practice and decision-making. We, therefore, examined the real world applicability of schizophrenia trials. Method:,A narrative overview of the content and quality of the randomized trials relevant to the care of those with schizophrenia is provided. Results:,Complex, explanatory, under-powered randomized drug trials dominate evaluative research in schizophrenia. Conclusion:,Explanatory designs are a necessary but insufficient step in establishing the true worth of interventions in schizophrenia. Research from other spheres of mental health and wider health care suggest that pragmatic trials are feasible. This design allows large scale trials to be conducted which include patients which we would recognize from routine practice and which record outcomes which are of genuine interest to decision-makers. [source] The magnocellular theory of developmental dyslexiaDYSLEXIA, Issue 1 2001John Stein Abstract Low literacy is termed ,developmental dyslexia' when reading is significantly behind that expected from the intelligence quotient (IQ) in the presence of other symptoms,incoordination, left,right confusions, poor sequencing,that characterize it as a neurological syndrome. 5,10% of children, particularly boys, are found to be dyslexic. Reading requires the acquisition of good orthographic skills for recognising the visual form of words which allows one to access their meaning directly. It also requires the development of good phonological skills for sounding out unfamiliar words using knowledge of letter sound conversion rules. In the dyslexic brain, temporoparietal language areas on the two sides are symmetrical without the normal left-sided advantage. Also brain ,warts' (ectopias) are found, particularly clustered round the left temporoparietal language areas. The visual magnocellular system is responsible for timing visual events when reading. It therefore signals any visual motion that occurs if unintended movements lead to images moving off the fovea (,retinal slip'). These signals are then used to bring the eyes back on target. Thus, sensitivity to visual motion seems to help determine how well orthographic skill can develop in both good and bad readers. In dyslexics, the development of the visual magnocellular system is impaired: development of the magnocellular layers of the dyslexic lateral geniculate nucleus (LGN) is abnormal; their motion sensitivity is reduced; many dyslexics show unsteady binocular fixation; hence poor visual localization, particularly on the left side (left neglect). Dyslexics' binocular instability and visual perceptual instability, therefore, can cause the letters they are trying to read to appear to move around and cross over each other. Hence, blanking one eye (monocular occlusion) can improve reading. Thus, good magnocellular function is essential for high motion sensitivity and stable binocular fixation, hence proper development of orthographic skills. Many dyslexics also have auditory/phonological problems. Distinguishing letter sounds depends on picking up the changes in sound frequency and amplitude that characterize them. Thus, high frequency (FM) and amplitude modulation (AM) sensitivity helps the development of good phonological skill, and low sensitivity impedes the acquisition of these skills. Thus dyslexics' sensitivity to FM and AM is significantly lower than that of good readers and this explains their problems with phonology. The cerebellum is the head ganglion of magnocellular systems; it contributes to binocular fixation and to inner speech for sounding out words, and it is clearly defective in dyslexics. Thus, there is evidence that most reading problems have a fundamental sensorimotor cause. But why do magnocellular systems fail to develop properly? There is a clear genetic basis for impaired development of magnocells throughout the brain. The best understood linkage is to the region of the Major Histocompatibility Complex (MHC) Class 1 on the short arm of chromosome 6 which helps to control the production of antibodies. The development of magnocells may be impaired by autoantibodies affecting the developing brain. Magnocells also need high amounts of polyunsaturated fatty acids to preserve the membrane flexibility that permits the rapid conformational changes of channel proteins which underlie their transient sensitivity. But the genes that underlie magnocellular weakness would not be so common unless there were compensating advantages to dyslexia. In developmental dyslexics there may be heightened development of parvocellular systems that underlie their holistic, artistic, ,seeing the whole picture' and entrepreneurial talents. Copyright © 2001 John Wiley & Sons, Ltd. [source] Analysis of landslide frequencies and characteristics in a natural system, coastal British ColumbiaEARTH SURFACE PROCESSES AND LANDFORMS, Issue 11 2004R. H. Guthrie Abstract Two hundred and one debris slides and debris ,ows were analyzed in a 286 km2 study area on the west coast of Vancouver Island, British Columbia, Canada. The study area remains essentially untouched by humans and therefore affords a natural setting in which to examine slope processes. Landslides were identi,ed and characterized on aerial photographs from 1:15 000 to 1:31 680, and were then mapped and transferred to a GIS for analysis. Based on detailed landslide surveys, we propose a new method to accurately determine volume of landslides of this type by measured total area. Results indicate average denudation rates of 56 m3 y,1 km,2, and higher natural rates of failure than analogous regions in coastal British Columbia. In contrast, the landslide rates are substantially less than those from forested watersheds. Landslide distribution is spatially clustered in air photograph epochs, and we propose intense storm cells within regional events as the causal mechanism. Further, failures occurred preferentially over the West Coast Crystalline Complex (by 1·4 times), a metamorphic assemblage of gabbros, schists and amphibolites, but 1·5 times less often over the Island Plutonic Suite, a granitic intrusive formation. The former result represents a new ,nding, while the latter corroborates ,ndings of previous authors. We examined magnitude,frequency relationships of the data set and present for the ,rst time a strong argument that the rollover effect is not merely an artefact, but is instead a consequence of the physical characteristics of the landslides themselves. We subsequently analyzed magnitude,frequency relationships from two other complete data sets from coastal British Columbia and produced a family of curves corroborating this result. Copyright © 2004 John Wiley & Sons, Ltd. [source] Adsorptive Stripping Voltammetric Determination of Trace Uranium with a Bismuth-Film Electrode Based on the U(VI),U(V) Reduction Step of the Uranium-Cupferron ComplexELECTROANALYSIS, Issue 3 2006Georgia Kefala Abstract This work reports the use of adsorptive stripping voltammetry (AdSV) for the determination of uranium on a preplated rotating-disk bismuth-film electrode (BiFE). The principle of the method relied on the complexation of U(VI) ions with cupferron and the subsequent adsorptive accumulation of the complex on the surface of the BiFE. The uranium in the accumulated complex was then reduced by means of a cathodic voltammetric scan while the analytically useful U(VI),U(V) reduction signal was monitored. The experimental variables as well as potential interferences were investigated and the figures of merit of the method were established. Using the selected conditions, the 3, limit of detection for uranium was 0.1,,g L,1 at a preconcentration time of 480,s and the relative standard deviation was 4.7% at the 5,,g L,1 level for a preconcentration time of 120,s (n=8). The accuracy of the method was established by analyzing a reference sea water sample. [source] Ion-Selective Electrodes for Thiocyanate Based on the Dinuclear Zinc(II) Complex of a Bis- N,O -bidentate Schiff BaseELECTROANALYSIS, Issue 12 2004Philippe Bühlmann Abstract An ion selective electrode based on the dinuclear complex formed by two zinc(II) ions and two molecules of the bis- N,O -bidentate Schiff base 2,2,-[methylenebis(4,1-phenylenenitrilomethylidyne)]bisphenol exhibits thiocyanate selectivity with a good discrimination of nitrite, nitrate, and azide. The selectivities of electrode membranes with various compositions indicate that this potentiometric selectivity is based on the formation of a 1,:,1 complex between the thiocyanate anion and the dinuclear ionophore. The 2,:,1 ratio of thiocyanate ions and the dinuclear ionophore that results from higher ratios of cationic sites and ionophore worsens the selectivity, suggesting that binding of a thiocyanate to both zinc(II) centers of the dinuclear ionophore is not favorable. Interestingly, the selectivity patterns of these electrodes differ radically from that of a highly sulfate selective electrode based on a compound reported previously to be the analogous mononuclear 1,:,1 complex of zinc(II) and the same Schiff base. It is suggested that the previously reported 1,:,1 complex with zinc(II) may indeed have been a polymer of the same elemental composition. [source] Electrocatalytic Properties of Electropolymerized Ni(II)curcumin ComplexELECTROANALYSIS, Issue 5-6 2003Aleksander Ciszewski Abstract The voltammetric behavior in alkaline solution of a nickel-based chemically modified electrode (poly-Ni(II)curcumin) prepared by oxidative electropolymerization of nickel-curcumin complex for electrooxidation of aliphatic alcohols was investigated by cyclic voltammetry and rotating disk technique (curcumin=1,7-bis[4-hydroxy-3-methoxyphenyl]-1,6-heptadiene-3,5-dione). The dependence of the oxidation current on the alcohol concentration and on the number of redox centers Ni(II)/Ni(III) is discussed. From the fact that the oxidation current increases with the increase of film thickness it is evident that the electrocatalytic reaction occurs inside the polymer film. The system examined is a typical example of a redox polymer with 3D properties. It is also concluded that the reaction mechanism of alcohol oxidation is the case, according to the concept of Andrieux and Saveant, where the cross-exchange reaction is the limiting step. The mechanism of modifying the film formation has also been discussed. [source] Mechanisms of Epileptogenesis in Tuberous Sclerosis Complex and Related Malformations of Cortical Development with Abnormal Glioneuronal ProliferationEPILEPSIA, Issue 1 2008Michael Wong Summary Malformations of cortical development (MCDs) are increasingly recognized as causes of medically intractable epilepsy. In order to develop more effective, rational therapies for refractory epilepsy related to MCDs, it is important to achieve a better understanding of the underlying mechanisms of epileptogenesis, but this is complicated by the wide variety of different radiographic, histopathological, and molecular features of these disorders. A subset of MCDs share a number of characteristic cellular and molecular abnormalities due to early defects in neuronal and glial proliferation and differentiation and have a particularly high incidence of epilepsy, suggesting that this category of MCDs with abnormal glioneuronal proliferation may also share a common set of primary mechanisms of epileptogenesis. This review critically analyzes both clinical and basic science evidence for overlapping mechanisms of epileptogenesis in this group of disorders, focusing on tuberous sclerosis complex, focal cortical dysplasia with balloon cells, and gangliogliomas. Specifically, the role of lesional versus perilesional regions, circuit versus cellular/molecular defects, and nonneuronal factors, such as astrocytes, in contributing to epileptogenesis in these MCDs is examined. An improved understanding of these various factors involved in epileptogenesis has direct clinical implications for optimizing current treatments or developing novel therapeutic approaches for epilepsy in these disorders. [source] Treatment before Seizures: New Indications for Antiepileptic Therapy in Children with Tuberous Sclerosis ComplexEPILEPSIA, Issue 8 2007Sergiusz Józwiak No abstract is available for this article. [source] Can Preventative Antiepileptic Therapy Alter Outcome in Infants with Tuberous Sclerosis Complex?EPILEPSIA, Issue 8 2007Carl E. Stafstrom No abstract is available for this article. [source] Consistent Localization of Interictal Epileptiform Activity on EEGs of Patients with Tuberous Sclerosis ComplexEPILEPSIA, Issue 3 2005Floor E. Jansen Summary:,Purpose: We addressed consistent localization of focal interictal epileptiform activity on EEGs of patients with tuberous sclerosis complex (TSC) and epilepsy. Methods: Twenty-one patients with TSC with a 10-year history of epilepsy and interictal epileptiform activity in three or more EEG recordings were included. None of the patients had undergone epilepsy surgery. Local maxima of interictal epileptiform activity were measured from 76 EEG traces and 33 EEG reports. Information about the patients' clinical course was extracted from their medical records. Magnetic resonance imaging (MRI) and neuropsychological examinations were performed. Statistical analysis was performed with the Mann,Whitney U test. Results: In eight patients, interictal epileptiform activity was consistently detected in one or two regions (group 1), and in 13 patients, epileptiform activity was detected in three or more regions (group 2). The number of foci increased throughout the disease course in both groups. Age at seizure onset and IQ were significantly higher in group 1. Complex partial seizures occurred more often in the patients of group 1. In 19 of the 21 patients, the most consistent epileptiform activity was localized in the frontotemporal region. Conclusions: Ninety percent of patients with TSC showed at least one region of consistent interictal epileptiform activity. Patients with one or two regions of epileptiform activity were older at seizure onset, often experienced complex partial seizures, and had mild or no mental deficits. These patients may be candidates for epilepsy surgery. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||