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Studies Support (studies + support)
Kinds of Studies Support Selected AbstractsAmyloid-Like Fibrillogenesis through Supramolecular Helix-Mediated Self-Assembly of Tetrapeptides Containing Non-Coded , -Aminoisobutyric Acid (Aib) and 3-Aminobenzoic Acid (m -ABA)HELVETICA CHIMICA ACTA, Issue 6 2010Arpita Dutta Abstract Single-crystal X-ray diffraction studies of two terminally protected tetrapeptides Boc-Ile-Aib-Val- m -ABA-OMe (I) and Boc-Ile-Aib-Phe- m -ABA-OMe (II) (Aib=, -aminoisobutyric acid; m -ABA=meta -aminobenzoic acid) reveal that they form continuous H-bonded helices through the association of double-bend (type III and I) building blocks. NMR Studies support the existence of the double-bend (type III and I) structures of the peptides in solution also. Field emission scanning electron-microscopic (FE-SEM) and high-resolution transmission electron-microscopic (HR-TEM) images of the peptides exhibit amyloid-like fibrils in the solid state. The Congo red-stained fibrils of peptide I and II, observed between crossed polarizers, show green-gold birefringence, a characteristic of amyloid fibrils. [source] Effects of supplemental L-methionine on E-64 [trans-epoxysuccinyl-1-leucyl-amido (4-guanido) butane]-induced dysmorphology in rat embryos cultured in vitroCONGENITAL ANOMALIES, Issue 4 2003Kouichi Yoshidome ABSTRACT E-64 [trans-epoxysuccinyl-1-leucylamido (4-guanido) butane] is teratogenic, inducing a spectrum of malformations in vivo and producing similar effects in vitro. Numerous studies support the concept that E-64-induced malformations result from embryonic nutritional deficiency, without affecting the maternal nutritional status. This has provided a useful model with which to investigate the nutritional requirements of the early embryo, as well as the role of various nutrients in the etiology of congenital defects. In the current investigation, we examined effects of L-methionine on E-64-induced embryotoxicity in vitro. For these experiments, we cultured rat embryos 9.5 days postconception (p.c.) for 48 hours with E-64 and/or L-methionine. We found that the addition of L-methionine to E-64-exposed cultures reduced optic abnormality and increased embryo protein. These results suggest that embryopathy largely results from a deficiency of L-methionine although E-64 limits the supply of all amino acids to the embryo. Furthermore, although endocytosis and degradation of proteins by the visceral yolk sac (VYS) supply most amino acids to the embryo, free amino acids may be compensatory when this source is reduced. These results support those of previous investigations that suggest L-methionine is a limiting nutrient for embryonic development. [source] Applications of cone-beam computed tomography in fractures of the maxillofacial complexDENTAL TRAUMATOLOGY, Issue 4 2009Werner H. Shintaku Several studies support the use of conventional two-dimensional imaging for traumas involving mainly the mandible, but for more complex situations advanced imaging modalities such as computed tomography (CT) and magnetic resonance imaging have higher indication. Nowadays, besides CT, cone-beam computed tomography (CBCT) has appeared as a reasonable and reliable alternative considering radiation dosage, image quality and comfort for the patient. The purpose of this study was to review the fracture patterns involving the maxillofacial complex, provide a technical and practical comparison between CT and CBCT, and finally present the potential applications of CBCT illustrated with clinical examples. [source] The cognitive phenotype in Klinefelter syndrome: A review of the literature including genetic and hormonal factorsDEVELOPMENTAL DISABILITIES RESEARCH REVIEW, Issue 4 2009Richard Boada Abstract Klinefelter syndrome (KS) or 47,XXY occurs in ,1 in 650 males. Individuals with KS often present with physical characteristics including tall stature, hypogonadism, and fertility problems. In addition to medical findings, the presence of the extra X chromosome can lead to characteristic cognitive and language deficits of varying severity. While a small, but significant downward shift in mean overall IQ has been reported, the general cognitive abilities of patients with KS are not typically in the intellectual disability range. Most studies support that males with KS have an increased risk of language disorders and reading disabilities. Results of other studies investigating the relationship between verbal and nonverbal/spatial cognitive abilities have been mixed, with differing results based on the age and ascertainment method of the cohort studied. Executive function deficits have been identified in children and adults with KS, however, the research in this area is limited and further investigation of the neuropsychological profile is needed. In this article, we review the strengths and weaknesses of previous cognitive and neuropsychological studies in males with KS in childhood and adulthood, provide historical perspective of these studies, and review what is known about how hormonal and genetic factors influence cognitive features in 47,XXY/KS. © 2009 Wiley-Liss, Inc. Dev Disabil Res Rev 2009;15:284,294. [source] Density-dependent dispersal in birds and mammalsECOGRAPHY, Issue 3 2005Erik Matthysen Density-dependent dispersal can be caused by various mechanisms, from competition inducing individuals to emigrate (positive density-dependence) to social crowding effects impeding free movement (negative density-dependence). Various spatial population models have incorporated positively density-dependent dispersal algorithms, and recent theoretical models have explored the conditions for density-dependent dispersal (DD) to evolve. However, while the existence of DD is well documented in some taxa such as insects, there is no clear picture on its generality in vertebrates. Here I review the available empirical data on DD in birds and mammals, focusing mainly on variation in dispersal between years and on experimental density manipulations. Surprisingly few studies have explicitly focused on DD, and interpretation of the available data is often hampered by differences in approach, small sample sizes and/or statistical shortcomings. Positive DD was reported in 50 and 33% of the selected mammal and bird studies, respectively, while two studies on mammals (out of eight) reported negative DD. Among bird studies, DD was more often reported for emigration rates or long-distance recoveries than for average distances within finite study areas. Experimental studies manipulating densities (mainly on mammals) have consistently generated positive DD, typically showing reduced emigration in response to partial population removal. Studies that examined dispersal in relation to seasonal changes in density (small mammals only) have more often reported negative DD. Studies that compared dispersal between sites differing in density, also show a mixture of positive and negative DD. This suggests that dispersal changes in a more complex way with seasonal and spatial density variation than with annual densities, and/or that these results are confounded by other factors differing between seasons and sites, such as habitat quality. I conclude that both correlational and experimental studies support the existence of positive, rather than negative, density-dependent dispersal in birds and mammals. [source] Polyunsaturated fatty acids and epilepsyEPILEPSIA, Issue 8 2010Ameer Y. Taha Summary Omega-3 and omega-6 polyunsaturated fatty acids (PUFAs) are dietary fatty acids that are involved in a myriad of physiologic processes in the brain. There is some evidence suggesting that PUFAs,and particularly omega-3 PUFAs,may have anticonvulsant effects, both in humans and in animals. In the present review, we assess the evidence related to the antiseizure properties of the n-3 PUFAs, discuss their possible mechanism(s) of action, and make recommendations for future clinical trials. In general, the available data from cell cultures and whole animal studies support the idea that the n-3 PUFAs have antiseizure properties. Future clinical trials involving the n-3 PUFAs should involve higher doses and longer periods of administration in order to definitively assess their possible antiseizure effects. [source] Family members of relatives with alcohol, drug and gambling problems: a set of standardized questionnaires for assessing stress, coping and strainADDICTION, Issue 11 2005Jim Orford ABSTRACT Aims To describe a set of standard questionnaire measures for the assessment of the needs of family members of relatives with alcohol, drug or gambling problems, and to present evidence of their reliability and validity from a series of related studies. Design Includes cross-sectional and repeated-measurement studies. Setting and participants Family members affected by and concerned about the problem drinking or drug-taking of close relatives in treatment and non-treatment samples in the United Kingdom (white and Sikh) and Mexico City; family members of untreated heavy drinkers; and family members of problem gamblers. Measurements Four measures derived from a stress,strain,coping,support model of alcohol, drugs and gambling problems and the family: Family Member Impact scale (FMI), Symptom Rating Test (SRT), Coping Questionnaire (CQ), and Hopefulness,Hopelessness scale (HOPE). FMI, SRT and CQ assess stress, strain and coping, respectively. The exact role of HOPE in the model remains to be determined. The support component remains unmeasured. Findings Results from a number of studies support the internal reliability, discriminant and construct validity and sensitivity to change of the SRT and its two constituent scales (psychological and physical symptoms) and at least two subscales of the CQ (engaged and tolerant,inactive coping). Although showing evidence of satisfactory reliability and some evidence of discriminant validity, further work may be required on the CQ withdrawal coping subscale. Evidence suggests that the FMI is reliable and valid and may have a factor structure that will support future research (distinguishing worrying behaviour from active disturbance). HOPE is a new measure showing promising characteristics. Conclusions A set of standard measures is available for helping to assess the needs of concerned and affected family members, derived from an explicit model of the family in relation to excessive drinking, drug taking or gambling. It may have a role to play in correcting the current neglect of the needs of such family members, estimated to be in the region of nearly a million adults in Britain alone. [source] REVIEW: Cognitive effects of nicotine: genetic moderatorsADDICTION BIOLOGY, Issue 3 2010Aryeh I. Herman ABSTRACT Cigarette smoking is the main preventable cause of death in developed countries, and the development of more effective treatments is necessary. Cumulating evidence suggests that cognitive enhancement may contribute to the addictive actions of nicotine. Several studies have demonstrated that nicotine enhances cognitive performance in both smokers and non-smokers. Genetic studies support the role of both dopamine (DA) and nicotinic acetylcholine receptors (nAChRs) associated with nicotine-induced cognitive enhancement. Based on knockout mice studies, ,2 nAChRs are thought to be essential in mediating the cognitive effects of nicotine. ,7nAChRs are associated with attentional and sensory filtering response, especially in schizophrenic individuals. Genetic variation in D2 type DA receptors and the catechol-O-methyltransferase enzyme appears to moderate cognitive deficits induced by smoking abstinence. Serotonin transporter (5-HTT) gene variation also moderates nicotine-induced improvement in spatial working memory. Less is known about the contribution of genetic variation in DA transporter and D4 type DA receptor genetic variation on the cognitive effects of nicotine. Future research will provide a clearer understanding of the mechanism underlying the cognitive-enhancing actions of nicotine. [source] Early processing in the human lateral occipital complex is highly responsive to illusory contours but not to salient regionsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2009Marina Shpaner Abstract Human electrophysiological studies support a model whereby sensitivity to so-called illusory contour stimuli is first seen within the lateral occipital complex. A challenge to this model posits that the lateral occipital complex is a general site for crude region-based segmentation, based on findings of equivalent hemodynamic activations in the lateral occipital complex to illusory contour and so-called salient region stimuli, a stimulus class that lacks the classic bounding contours of illusory contours. Using high-density electrical mapping of visual evoked potentials, we show that early lateral occipital cortex activity is substantially stronger to illusory contour than to salient region stimuli, whereas later lateral occipital complex activity is stronger to salient region than to illusory contour stimuli. Our results suggest that equivalent hemodynamic activity to illusory contour and salient region stimuli probably reflects temporally integrated responses, a result of the poor temporal resolution of hemodynamic imaging. The temporal precision of visual evoked potentials is critical for establishing viable models of completion processes and visual scene analysis. We propose that crude spatial segmentation analyses, which are insensitive to illusory contours, occur first within dorsal visual regions, not the lateral occipital complex, and that initial illusory contour sensitivity is a function of the lateral occipital complex. [source] Synthesis of Triazole-Bridged Unsymmetrical Porphyrin Dyads and Porphyrin,Ferrocene ConjugatesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 3 2010Vijayendra S. Shetti Abstract A simple method has been used to synthesize four porphyrin azides with cores such as N4, N3S, N2SO and N2S2 in 60,90,% yields by treating the corresponding aminoporphyrins with tert -butyl nitrite (tBuONO) and azidotrimethylsilane (TMSN3) in THF/CH3CN under mild reaction conditions. The hitherto unknown aminoporphyrins with heteroatom cores were synthesized from their corresponding nitroporphyrins by standard SnCl2/HCl reduction. The azidoporphyrins were used to synthesize six triazole-bridged unsymmetrical porphyrin dyads containing two different types of porphyrin sub-units as well as five triazole-bridged porphyrin,ferrocene conjugates under CuI -catalyzed "click" reaction conditions. Various CuI -catalyzed reaction conditions were studied and the best yields of triazole-bridged dyads and conjugates were obtained with CuI/DIPEA in THF/CH3CN at room temperature for overnight. The unsymmetrical porphyrin dyads and porphyrin,ferrocene conjugates were characterized by various spectroscopic and electrochemical techniques. In unsymmetrical porphyrin dyads, the NMR, absorption and electrochemical studies indicate a weak interaction between the two porphyrin sub-units. However, preliminary photophysical studies support an efficient singlet-singlet energy transfer from one porphyrin unit to another in five unsymmetrical dyads reported here. In porphyrin,ferrocene conjugates, the fluorescence of porphyrin was quenched significantly due to photo-induced electron transfer from ferrocene to porphyrin. [source] Mapping the Mechanism of Nickel-Ferrophite Catalysed Methylation of Baylis,Hillman-Derived SN2, ElectrophilesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 6 2009Andrew Novak Abstract Enantioselective Ni-catalysed methylation of Baylis,Hillman-derived allylic electrophiles in the presence of ferrophite ligands has been investigated computationally and experimentally. The sense and degree of enantioselectivity attained is independent of both the leaving group and the isomeric structure of the initial allylic halide. DFT studies support the selective formation of a limited number of energetically favoured anti and syn ,-allyl intermediates. The observed regio- and enantioselectivity can be rationalised based on the energetics of these structures. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Informational intra-group influence: the effects of time pressure and group sizeEUROPEAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 1 2008Bryan L. Bonner The judgments of groups have immense impact on our daily lives. This paper theorizes that three families of intra-group influence affect the collective estimation process. These different forms of influence map to different levels of task demonstrability, or the extent to which correct answers are transparent to problem-solvers. When demonstrability is low, group estimates are disproportionately influenced by proposals closer to the intra-group mean (centrality). When demonstrability is high and groups are small, group decisions are disproportionately influenced by proposals closer to the correct answer (accuracy). Finally, when demonstrability is high and groups are larger, group decisions are disproportionately influenced by proposals offered by generally more accurate individuals across a set of judgments (expertise). Three laboratory studies support our predictions with regard to informational influence in cooperative groups. Copyright © 2006 John Wiley & Sons, Ltd. [source] The illusion of group productivity: a reduction of failures explanationEUROPEAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 1 2006Bernard A. Nijstad It has consistently been found that people produce more ideas when working alone as compared to when working in a group. Yet, people generally believe that group brainstorming is more effective than individual brainstorming. Further, group members are more satisfied with their performance than individuals, whereas they have generated fewer ideas. We argue that this ,illusion of group productivity' is partly due to a reduction of cognitive failures (instances in which someone is unable to generate ideas) in a group setting. Three studies support that explanation, showing that: (1) group interaction leads to a reduction of experienced failures and that failures mediate the effect of setting on satisfaction; and (2) manipulations that affect failures also affect satisfaction ratings. Implications for group work are discussed. Copyright © 2005 John Wiley & Sons, Ltd. [source] Proteolytic activation and function of the cytokine Spätzle in the innate immune response of a lepidopteran insect, Manduca sextaFEBS JOURNAL, Issue 1 2010Chunju An The innate immune response of insects includes induced expression of genes encoding a variety of antimicrobial peptides. The signaling pathways that stimulate this gene expression have been well characterized by genetic analysis in Drosophila melanogaster, but are not well understood in most other insect species. One such pathway involves proteolytic activation of a cytokine called Spätzle, which functions in dorsal,ventral patterning in early embryonic development and in the antimicrobial immune response in larvae and adults. We have investigated the function of Spätzle in a lepidopteran insect, Manduca sexta, in which hemolymph proteinases activated during immune responses have been characterized biochemically. Two cDNA isoforms for M. sexta Spätzle-1 differ because of alternative splicing, resulting in a 10 amino acid residue insertion in the pro-region of proSpätzle-1B that is not present in proSpätzle-1A. The proSpätzle-1A cDNA encodes a 32.7 kDa polypeptide that is 23% and 44% identical to D. melanogaster and Bombyx mori Spätzle-1, respectively. Recombinant proSpätzle-1A was a disulfide-linked homodimer. M. sexta hemolymph proteinase 8 cleaved proSpätzle-1A to release Spätzle-C108, a dimer of the C-terminal 108 residue cystine-knot domain. Injection of Spätzle-C108, but not proSpätzle-1A, into larvae stimulated expression of several antimicrobial peptides and proteins, including attacin-1, cecropin-6, moricin, lysozyme, and the immunoglobulin domain protein hemolin, but did not significantly affect the expression of two bacteria-inducible pattern recognition proteins, immulectin-2 and ,-1,3-glucan recognition protein-2. The results of this and other recent studies support a model for a pathway in which the clip-domain proteinase pro-hemolymph proteinase 6 becomes activated in plasma upon exposure to Gram-negative or Gram-positive bacteria or to ,-1,3-glucan. Hemolymph proteinase 6 then activates pro-hemolymph proteinase 8, which in turn activates Spätzle-1. The resulting Spätzle-C108 dimer is likely to function as a ligand to activate a Toll pathway in M. sexta as a response to a wide variety of microbial challenges, stimulating a broad response to infection. Structured digital abstract ,,MINT-7295125: Spätzle 1A (uniprotkb:C8BMD1) and Spätzle 1A (uniprotkb:C8BMD1) bind (MI:0407) by comigration in gel electrophoresis (MI:0807) [source] Influences of species, latitudes and methodologies on estimates of phenological response to global warmingGLOBAL CHANGE BIOLOGY, Issue 9 2007CAMILLE PARMESANArticle first published online: 14 AUG 200 Abstract New analyses are presented addressing the global impacts of recent climate change on phenology of plant and animal species. A meta-analysis spanning 203 species was conducted on published datasets from the northern hemisphere. Phenological response was examined with respect to two factors: distribution of species across latitudes and taxonomic affiliation or functional grouping of target species. Amphibians had a significantly stronger shift toward earlier breeding than all other taxonomic/functional groups, advancing more than twice as fast as trees, birds and butterflies. In turn, butterfly emergence or migratory arrival showed three times stronger advancement than the first flowering of herbs, perhaps portending increasing asynchrony in insect,plant interactions. Response was significantly stronger at higher latitudes where warming has been stronger, but latitude explained < 4% of the variation. Despite expectation, latitude was not yet an important predictor of climate change impacts on phenology. The only two previously published estimates of the magnitude of global response are quite different: 2.3 and 5.1 days decade,1 advancement. The scientific community has assumed this difference to be real and has attempted to explain it in terms of biologically relevant phenomena: specifically, differences in distribution of data across latitudes, taxa or time periods. Here, these and other possibilities are explored. All analyses indicate that the difference in estimated response is primarily due to differences between the studies in criteria for incorporating data. It is a clear and automatic consequence of the exclusion by one study of data on ,stable' (nonresponsive) species. Once this is accounted for, the two studies support each other, generating similar conclusions despite analyzing substantially nonoverlapping datasets. Analyses here on a new expanded dataset estimate an overall spring advancement across the northern hemisphere of 2.8 days decade,1. This is the first quantitative analysis showing that data-sampling methodologies significantly impact global (synthetic) estimates of magnitude of global warming response. [source] Use of ristocetin cofactor activity in the management of von Willebrand diseaseHAEMOPHILIA, Issue 2001B.M. Ewenstein von Willebrand disease (vWD), the most common of the hereditary bleeding disorders, arises from quantitative or qualitative defects in von Willebrand factor (vWF). vWF is a multimeric plasma protein that plays a key role in primary and secondary haemostasis. In the current classification scheme, vWD is divided into six subtypes that are based on the nature of the vWF defect. Therapeutic strategies depend on the accurate identification of these subtypes. In most clinical situations, desmopressin is effective treatment for the great majority of patients with mild (type 1) disease, while replacement therapy with factor VIII/vWF concentrates that contain high levels of vWF activity is required for most type 2 and nearly all type 3 vWD patients. Several factor VIII/vWF replacement products are available, one of which (Humate P) has been approved for the treatment of vWD by the US Food and Drug Administration. Preliminary results of recent studies support the hypothesis that treatment with factor VIII/vWF concentrates based upon the content of vWF activity as reflected in the ristocetin cofactor assay is practicable, safe and efficacious. The establishment of optimal treatment regimens with respect to dose intensity and duration will require further study. [source] A stem lineage representative of buttonquails from the Lower Oligocene of Germany , fossil evidence for a charadriiform origin of the TurnicidaeIBIS, Issue 4 2007GERALD MAYR A new species of the charadriiform taxon Turnipax Mayr, 2000 is described from the Lower Oligocene fossil site Frauenweiler in southern Germany. The postcranial skeleton assigned to Turnipax oechslerorum sp. nov. is very well preserved and allows the recognition of significant, previously unknown osteological details of Turnipax, especially concerning the wing and pectoral girdle bones. We provide evidence that Turnipax is a stem lineage representative of the Turnicidae (buttonquails) and synonymize Turnipacidae Mayr, 2000 with Turnicidae Gray, 1840. Turnipax is the earliest fossil representative of the Turnicidae, which otherwise have no Paleogene fossil record. Because recent molecular studies support a charadriiform origin of buttonquails, the mosaic distribution in the skeleton of Turnipax of derived features of the Turnicidae and non-turnicid charadriiform birds is of particular interest. Turnipax exhibits a more plesiomorphic morphology than extant Turnicidae, and we assume that its habitat and way of living differed from that of crown group Turnicidae, which may not have diversified before the spread of grasslands during the Oligocene and Miocene. [source] Role of the Toll/interleukin-1 receptor signaling pathway in host resistance and pathogenesis during infection with protozoan parasitesIMMUNOLOGICAL REVIEWS, Issue 1 2004Ricardo T. Gazzinelli Summary:, Different studies have illustrated the activation of the innate immune system during infection with protozoan parasites. Experiments performed in vivo also support the notion that innate immunity has a crucial role in resistance as well as pathogenesis observed during protozoan infections such as malaria, leishmaniasis, toxoplasmosis, and trypanosomiasis. While major advances have been made in the assignment of bacterial molecules as Toll-like receptors (TLRs) agonists as well as defining the role of the Toll/interleukin-1 receptor (TIR) signaling pathway in host resistance to bacterial infection, this research area is now emerging in the field of protozoan parasites. In this review, we discuss the recent studies describing parasite molecules as TLR agonists and those studies indicating the essential role of the TIR-domain bearing molecule named myeloid differentiation factor 88 in host resistance to infection with protozoan parasites. Together, these studies support the hypothesis that the TIR signaling pathway is involved in the initial recognition of protozoan parasites by the immune system of the vertebrate host, early resistance to infection, development of acquired immunity, as well as pathology observed during acute infection with this class of pathogens. [source] Report on the vitamin D status of adult and pediatric patients with inflammatory bowel disease and its significance for bone health and diseaseINFLAMMATORY BOWEL DISEASES, Issue 12 2006Helen M. Pappa MD Abstract Vitamin D is a hormone responsible for calcium homeostasis and essential for bone mineralization throughout the lifespan. Recent studies revealed a high prevalence of hypovitaminosis D among healthy adults and children, especially in the northern hemisphere, and a link between this condition and suboptimal bone health. Moreover, maintenance of what are today considered optimal vitamin D stores has not been achieved throughout the year with currently recommended daily intake for vitamin D. The prevalence of hypovitaminosis D is even higher among adults with inflammatory bowel disease (IBD), a situation that may be caused by malabsorption and gastrointestinal losses through an inflamed intestine, among other factors. In children with IBD, existing reports of vitamin D status are scarce. The relationship between vitamin D status and bone health, although well-established in healthy adults and children, has been controversial among adults and children with IBD, and the reasons for this have not been investigated to date. Studies in animal models of colitis and in vitro human studies support a role of vitamin D in the regulation of the immune system of the gut and the potential of vitamin D and its derivatives as therapeutic adjuncts in the treatment of IBD. This role of vitamin D has not been investigated with translational studies to date. Currently, there are no guidelines for monitoring vitamin D status, treating hypovitaminosis D, and maintaining optimal vitamin D stores in patients with IBD. These tasks may prove particularly difficult because of malabsorption and gastrointestinal losses that are associated with IBD. [source] Origin of multifocal carcinomas of the bladder and upper urinary tract: Molecular analysis and clinical implicationsINTERNATIONAL JOURNAL OF UROLOGY, Issue 8 2005TOMONORI HABUCHI Abstract The simultaneous or metachronous development of multifocal tumors with identical or variable histological features in the urothelial tract in a single patient is a well-known characteristic of urothelial cancer. To explain this phenomenon, two distinct concepts have been proposed: the ,field defect' hypothesis according to which urothelial cells in patients are primed to undergo transformation by previous carcinogenic insults and the ,single progenitor cell' hypothesis, which asserts that the multifocal development is caused by the seeding or intraepithelial spread of transformed cells. Results of recent molecular genetic studies support the ,single progenitor cell' hypothesis, and indicate that the genetic and phenotypic diversity observed in multifocal urothelial tumors is a consequence of clonal evolution from a single transformed cell. An understanding of the mechanism of the heterotopic recurrence of urothelial cancer may provide new prospects for early molecular detection and prevention of heterotopic recurrence of urothelial cancer. [source] Nutrient Uptake and Mineralization during Leaf Decay in Streams , a Model SimulationINTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 4 2009J. R. Webster Abstract We developed a stoichiometrically explicit computer model to examine how heterotrophic uptake of nutrients and microbial mineralization occurring during the decay of leaves in streams may be important in modifying nutrient concentrations. The simulations showed that microbial uptake can substantially decrease stream nutrient concentrations during the initial phases of decomposition, while mineralization may produce increases in concentrations during later stages of decomposition. The simulations also showed that initial nutrient content of the leaves can affect the stream nutrient concentration dynamics and determine whether nitrogen or phosphorus is the limiting nutrient. Finally, the simulations suggest a net retention (uptake > mineralization) of nutrients in headwater streams, which is balanced by export of particulate organic nutrients to downstream reaches. Published studies support the conclusion that uptake can substantially change stream nutrient concentrations. On the other hand, there is little published evidence that mineralization also affects nutrient concentrations. Also, there is little information on direct microbial utilization of nutrients contained in the decaying leaves themselves. Our results suggest several directions for research that will improve our understanding of the complex relationship between leaf decay and nutrient dynamics in streams. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The potential for ,-opioid receptor agonists to be anti-emetic in humans: a review of clinical dataACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 2 2010KEVIN D. JOHNSTON In animal models of vomiting, ,-opioid (MOP, OP3) receptors mediate both emesis and anti-emesis. ,-receptors within the blood,brain barrier, mediating anti-emesis, are more rapidly accessible to lipid-soluble ,-opioid receptor agonists such as fentanyl than to morphine, and fentanyl has broad-spectrum anti-emetic effects in a number of species. Whether a similar situation exists in humans is not known. A search was performed for clinical studies comparing the emetic side effects of opioids administered peri-operatively in an attempt to identify differences between morphine and more lipid-soluble ,-receptor-selective agonists such as fentanyl. Overall, the evidence appears to suggest that fentanyl and other phenylpiperidines are associated with less nausea and vomiting than morphine, but not all studies support this, and fentanyl-like drugs are associated with nausea and vomiting per se. Good evidence, however, exists to show that fentanyl and alfentanil do not cause more nausea and vomiting than the ultra fast-acting remifentanil. Because remifentanil is cleared rapidly post-operatively, such trials suggest that the emetic side effects of fentanyl and alfentanil are minimal. The clinical evidence, although limited, is at least consistent with the possibility that central ,-opioid receptors may mediate anti-emesis in humans. It is possible that the role of ,-opioid agonists in anti-emesis may become clearer in the future as a result of the use of peripheral ,-opioid receptor antagonists. [source] Reciprocal phenotypic plasticity can lead to stable predator,prey interactionJOURNAL OF ANIMAL ECOLOGY, Issue 6 2009Akihiko Mougi Summary 1.,Inducible defences of prey and inducible offences of predators are prevalent strategies in trophic interactions with temporal variation. Due to the inducible properties of the functional traits themselves, which drive the dynamic predator,prey relationship on an ecological time-scale, predator and prey may reciprocally interact through their inducible traits (i.e. reciprocal phenotypic plasticity). 2.,Although overwhelming evidence of the stabilizing effect of inducible traits in either species on community dynamics forcefully suggests a critical ecological role for reciprocal plasticity in predator,prey population dynamics, our understanding of its ecological consequences is very limited. 3.,Within a mathematical modelling framework, we investigated how reciprocal plasticity influences the stability of predator,prey systems. 4.,By assuming two types of phenotypic shift, a density-dependent shift and an adaptive phenotypic shift, we examined two interaction scenarios with reciprocal plasticity: (i) an arms-race-like relationship, in which the defensive prey phenotype is more protective against both predator phenotypes (i.e. normal and offensive) than the normal prey phenotype, and the offensive predator is a more efficient consumer, preying upon both prey phenotypes (i.e. normal and defensive), than the normal predator and (ii) a matching response-like relationship, in which the offensive predator consumes more defensive prey and fewer normal prey than the normal predator. 5.,Results of both phenotypic shift models consistently suggest that given the used set of parameter values, the arms-race-like reciprocal plasticity scenario has the largest stability area, when compared with the other scenarios. In particular, higher stability is achieved when the prey exhibits a high-performance inducible defence. Furthermore, this stabilization is so strong that the destabilizing effects of enrichment may be eliminated, even though the higher flexibility of plasticity does not always stabilize a system. 6.,Recent empirical studies support our model predictions. Clear-cut examples of reciprocal phenotypic plasticity show an arms-race-like relationship in which prey species exhibit induced high-performance defences. We may need to re-examine reported predator,prey interactions in which predator or prey exhibits inducible plasticity to determine whether arms-race-like reciprocal plasticity is a general ecological phenomenon. [source] Eucalyptus pollen grain emptying by two Australian nectarivorous psittacinesJOURNAL OF AVIAN BIOLOGY, Issue 3 2001B. D. Gartrell The relative importance of pollen as a source of protein to vertebrates is controversial. In nectarivorous psittacine birds, field studies support its importance, but an experimental study in a nectarivorous parrot showed that less than 7% of pollen grains were emptied. We investigated pollen grain emptying by two nectarivorous Australian parrots, the Swift Parrot Lathamus discolor and the Musk Lorikeet Glossopsitta concinna. We used a controlled experiment, and examined pollen located at different levels through the alimentary tract of wild L. discolor. There was significant emptying of pollen grains (x=45.4%±1.91 s.e.) by all birds in the experimental trials. There was also a progressive increase in the percentage of pollen grains emptied at different sites along the alimentary tract in wild birds (crop x=24.2%±4.44 s.e., proventriculus x=34.0%±7.29 s.e., duodenum x=54.3%±5.42 s.e. and distal intestine x=64.2%±4.68 s.e.). The percentage of pollen grains emptied by captive L. discolor in the experimental trial (x=44.1%±2.77 s.e.) was not significantly different from that found in wild L. discolor (x=40.3%±4.25 s.e.). Both species of nectarivorous parrot were able to rapidly ingest large quantities of Eucalyptus pollen and appeared to empty the pollen grains efficiently. Eucalyptus pollen appears to be an important source of protein for these birds. [source] In defense of clinical judgment , and mechanical predictionJOURNAL OF BEHAVIORAL DECISION MAKING, Issue 5 2006Jason Dana Abstract Despite over 50 years of one-sided research favoring formal prediction rules over human judgment, the "clinical-statistical controversy," as it has come to be known, remains something of a hot-button issue. Surveying the objections to the formal approach, it seems the strongest point of disagreement is that clinical expertise can be replaced by statistics. We review and expand upon an unfortunately obscured part of Meehl's book to try to reconcile the issue. Building on Meehl, we argue that the clinician provides information that cannot be captured in, or outperformed by, mere frequency tables. However, that information is still best harnessed by a mechanical prediction rule that makes the ultimate decision. Two original studies support our arguments. The first study shows that multivariate prediction models using no data other than clinical speculations can perform well against statistical regression models. Study 2, however, showed that holistic predictions were less accurate than predictions made by mechanically combining smaller judgments without input from the judge at the combination stage. While we agree that clinical expertise cannot be replaced or neglected, we see no ethical reason to resist using explicit, mechanical rules for socially important decisions. Copyright © 2006 John Wiley & Sons, Ltd. [source] Cancer stem cells in leukemia, recent advancesJOURNAL OF CELLULAR PHYSIOLOGY, Issue 2 2007Gang-Ming Zou The history of stem cell research was started in the early 1900s in Europe where the researcher realized that various types of blood cells came from a particular "stem cells." However, it was not until 1963 that the first quantitative description of the self-renewal activities of transplanted mouse bone marrow cells were documented by Canadian scientist Ernest A McCulloch and James E Till in Toronto. The concept of cancer stem cells has been used over 50 years ago; whereas the strong evidence for the existence of a Cancer Stem Cells was obtained recently. Consequently, there is increasing attention in recent year about cancer stem cells. The findings from recent studies support the concept that stem cells are integral to the development of several forms of human cancer. Changes in stem cell behavior can contribute to tumor formation. Leukemia is a cancer of blood-forming tissue, including the bone marrow and lymphatic system. Leukemic stem cells represent the cancer stem cells in the leukemia. In this review, we summarize the recent advance in the study of leukemic stem cells. J. Cell. Physiol. 213: 440,444, 2007. © 2007 Wiley-Liss, Inc. [source] Food for thought: the effect of counterfactual thinking on the use of nutrition informationJOURNAL OF CONSUMER BEHAVIOUR, Issue 3 2010Khaled Aboulnasr In three experiments, we examine the efficacy of counterfactual thinking (CFT) as a strategy to enhance consumers' motivation to process and use nutrition information on food packages. In the first study, we test whether CFT leads to greater motivation to process nutrition label information in the process of forming product attitudes. We also test whether motivation mediates the relationship between CFT and the influence of the nutrition label in product evaluation. In a second study, we test the effect of upward versus downward CFT on motivation. We also examine whether nutrition information on food packages moderates the relationship between CFT and product attitudes. In a third study, we examined the duration of the motivational effect of CFT. Results from the three studies support the role of CFT as a mechanism that enhances consumers' motivation to elaborate on and use nutrition information to form product attitudes. Copyright © 2010 John Wiley & Sons, Ltd. [source] Protein tyrosine phosphatase 1B: a new target for the treatment of obesity and associated co-morbiditiesJOURNAL OF INTERNAL MEDICINE, Issue 6 2002O. Ukkola Abstract.,Ukkola O, Santaniemi M (University of Oulu, Oulu, Finland). Protein tyrosine phosphatase 1B: a new target for the treatment of obesity and associated co-morbidities (Review). J Intern Med 2002; 251: 467,475. Impaired insulin action is important in the pathophysiology of multiple metabolic abnormalities such as obesity and type 2 diabetes. Protein tyrosine phosphatase 1B (PTP1B) is considered a negative regulator of insulin signalling. This is best evidenced by studies on knockout mice showing that lack of PTP1B is associated with increased insulin sensitivity as well as resistance to obesity and in vitro studies whilst studies in animals and humans have given contradictory results. However, several studies support the notion that insulin signalling can be enhanced by the inhibition of PTP1B providing an attractive target for therapy against type 2 diabetes and obesity. In addition, recent genetic studies support the association between PTP1B with insulin resistance. The development of PTP1B inhibitors has already begun although it has become clear that is not easy to find both a selective, safe and effective PTP1B inhibitor. The objective of this paper is to review the current evidence of PTP1B in the pathophysiology of obesity, type 2 diabetes and cancer as well as in the treatment of these disorders. [source] 3-Nitropropionic acid: a mitochondrial toxin to uncover physiopathological mechanisms underlying striatal degeneration in Huntington's diseaseJOURNAL OF NEUROCHEMISTRY, Issue 6 2005Emmanuel Brouillet Abstract Huntington's disease (HD) is a neurodegenerative disorder caused by a mutation in the gene encoding Huntingtin. The mechanisms underlying the preferential degeneration of the striatum, the most striking neuropathological change in HD, are unknown. Of those probably involved, mitochondrial defects might play an important role. The behavioural and anatomical similarities found between HD and models using the mitochondrial toxin 3-nitropropionic acid (3NP) in rats and primates support this hypothesis. Here, we discuss the recently identified mechanisms of 3NP-induced striatal degeneration. Two types of important factor have been identified. The first are the ,executioner' components that have direct roles in cell death, such as c-Jun N-terminal kinase and Ca2+ -activated protease calpains. The second are ,environmental' factors, such as glutamate, dopamine and adenosine, which modulate the striatal degeneration induced by 3NP. Interestingly, these recent studies support the hypothesis that 3NP and mutated Huntingtin have certain mechanisms of toxicity in common, suggesting that the use of 3NP might give new insights into the pathogenesis of HD. Research on 3NP provides additional proof that the neurochemical environment of a given neurone can determine its preferential vulnerability in neurodegenerative diseases. [source] Insulin-like growth factor-I-stimulated Akt phosphorylation and oligodendrocyte progenitor cell survival require cholesterol-enriched membranesJOURNAL OF NEUROSCIENCE RESEARCH, Issue 15 2009Robert J. Romanelli Abstract Previously we showed that insulin-like growth factor-I (IGF-I) promotes sustained phosphorylation of Akt in oligodendrocyte progenitor cells (OPCs) and that Akt phosphorylation is required for survival of these cells. The direct mechanisms, however, by which IGF-I promotes Akt phosphorylation are currently undefined. Recently, cholesterol-enriched membranes (CEMs) have been implicated in regulation of growth factor-mediated activation of the PI3K/Akt pathway and survival of mature oligodendrocytes; however, less is know about their role in OPC survival. In the present study, we investigate the role of CEMs in IGF-I-mediated Akt phosphorylation and OPC survival. We report that acute disruption of membrane cholesterol with methyl-,-cyclodextrin results in altered OPC morphology and inhibition of IGF-I-mediated Akt phosphorylation. We also report that long-term inhibition of cholesterol biosynthesis with 25-hydroxycholesterol blocks IGF-I stimulated Akt phosphorylation and cell survival. Moreover, we show that the PI3K regulatory subunit, p85, Akt, and the IGF-IR are sequestered within cholesterol-enriched fractions in steady-state stimulation of the IGF-IR and that phosphorylated Akt and IGF-IR are present in cholesterol-enriched fractions with IGF-I stimulation. Together, the results of these studies support a role for CEMs or "lipid rafts" in IGF-I-mediated Akt phosphorylation and provide a better understanding of the mechanisms by which IGF-I promotes OPC survival. © 2009 Wiley-Liss, Inc. [source] | |||||||||||||||||||||||||||||||||||||