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Local Factors (local + factor)
Selected AbstractsLiver cirrhosis in an infant with Chanarin,Dorfman syndrome caused by a novel splice-site mutation in ABHD5ACTA PAEDIATRICA, Issue 10 2010M Cakir Abstract We described a Turkish girl with Chanarin,Dorfman syndrome who developed liver cirrhosis in the early infancy. She had all the clinical features of Chanarin,Dorfman syndrome such as ichthyosis, Jordan's anomaly, fatty liver disease and mild ectropion. The diagnosis was confirmed with a novel ABHD5 mutation. Liver steatosis or steatohepatitis with or without hepatomegaly is the predominant finding of Chanarin,Dorfman syndrome. Cirrhosis has been reported in patients with long-duration disease. Conclusion:, Local factors or dysfunction of local proteins such as mutations or polymorphisms in hepatic microsomal lipase and arylacetamide deacetylase may contribute the severity of liver involvement, and steatosis may progress to cirrhosis in the early infancy in Chanarin,Dorfman syndrome. [source] Control of muscle blood flow during exercise: local factors and integrative mechanismsACTA PHYSIOLOGICA, Issue 4 2010I. Sarelius Abstract Understanding the control mechanisms of blood flow within the vasculature of skeletal muscle is clearly fascinating from a theoretical point of view due to the extremely tight coupling of tissue oxygen demands and blood flow. It also has practical implications as impairment of muscle blood flow and its prevention/reversal by exercise training has a major impact on widespread diseases such as hypertension and diabetes. Here we analyse the role of mediators generated by skeletal muscle activity on smooth muscle relaxation in resistance vessels in vitro and in vivo. We summarize their cellular mechanisms of action and their relative roles in exercise hyperaemia with regard to early and late responses. We also discuss the consequences of interactions among mediators with regard to identifying their functional significance. We focus on (potential) mechanisms integrating the action of the mediators and their effects among the cells of the intact arteriolar wall. This integration occurs both locally, partly due to myoendothelial communication, and axially along the vascular tree, thus enabling the local responses to be manifest along an entire functional vessel path. Though the concept of signal integration is intriguing, its specific role on the control of exercise hyperaemia and the consequences of its modulation under physiological and pathophysiological conditions still await additional analysis. [source] Connective tissue growth factor and cardiac fibrosisACTA PHYSIOLOGICA, Issue 3 2009A. Daniels Abstract Cardiac fibrosis is a major pathogenic factor in a variety of cardiovascular diseases and refers to an excessive deposition of extracellular matrix components in the heart, which leads to cardiac dysfunction and eventually overt heart failure. Evidence is accumulating for a crucial role of connective tissue growth factor (CTGF) in fibrotic processes in several tissues including the heart. CTGF orchestrates the actions of important local factors evoking cardiac fibrosis. The central role of CTGF as a matricellular protein modulating the fibrotic process in cardiac remodelling makes it a possible biomarker for cardiac fibrosis and a potential candidate for therapeutic intervention to mitigate fibrosis in the heart. [source] Effects of landscape structure and habitat type on a plant-herbivore-parasitoid communityECOGRAPHY, Issue 3 2003Andreas Kruess The effects of local habitat and large-scale landscape factors on species diversity and species interactions were studied using the insect community in stems of the creeping thistle Cirsium arvense. Thistle abundance was higher in fallows than in crop fields and field margins, with fallows providing 67% of thistle abundance within 15 study areas on a landscape scale. Species richness of the herbivores was positively related with thistle abundance, parasitoid species richness was influenced by habitat type and was positively correlated with herbivore species richness. The abundance of herbivores and parasitoids was affected by local factors such as habitat type and host abundance, but also by landscape factors such as the percentage of non-crop area and the isolation of habitats. The infestation rate caused by the agromyzid Melanagromyza aeneoventris was positively related to percent non-crop area, whereas the parasitism rate of this fly increased with increasing habitat diversity on the landscape scale. For these two interactions and for total herbivore abundance, a scale-dependency of the landscape effects was found. The results emphasize that biological diversity and ecological functions within a plant-insect community are not only affected by local habitat factors but also by large-scale landscape characteristics. Hence, to improve future agri-environmental schemes for biodiversity conservation and biological control large-scale landscape effects and their scale-dependency should be considered. [source] Hydrological connectivity in coastal inland systems: lessons from a Neotropical fish metacommunityECOLOGY OF FRESHWATER FISH, Issue 1 2010P. H. M. De Macedo-Soares de Macedo-Soares PHM, Petry AC, Farjalla VF, Caramaschi EP. Hydrological connectivity in coastal inland systems: lessons from a Neotropical fish metacommunity. Ecology of Freshwater Fish 2010: 19: 7,18. © 2009 John Wiley & Sons A/S Abstract,,, We assessed the influence of hydrological connectivity in structuring fish communities through seasonal samplings of environmental variables and fishes in a coastal lagoon and associated pools in the Restinga de Jurubatiba National Park, Brazil. Community structure attributes such as species richness, numerical density and biomass, Shannon,Wiener diversity index and evenness were compared between periods of the lowest and highest hydrological connectivity, while the environmental gradient and fish zonation were explored through ordination techniques. The greater hydrological connectivity established in the rainy season promoted the homogenisation of most environmental variables and fish species, which differed markedly from the arrangement observed in the dry season. Despite variation in fish species composition, community attributes showed non-significant differences between the dry and rainy seasons. The patterns of composition and numerical density in pools were strongly influenced by local factors, especially salinity, dissolved oxygen, total phosphorous concentration and water colour in the dry season, in addition to total nitrogen concentration and depth in the rainy season. Comparable to the role played by flood pulses in river-floodplain systems, the hydrological connectivity in these tropical coastal waterbodies seems to strongly influence fish community structure, and, therefore to determine regional biodiversity. [source] Anatomy of an overfill: a reflection on the processENDODONTIC TOPICS, Issue 1 2007ALAN H. GLUSKIN The design and implementation of shaping, cleaning and sealing objectives in root canal therapy are fraught with real and potential pitfalls when the anatomic complexity of the space and technical considerations for its instrumentation, disinfection and obturation are contemplated. This review will focus on the genesis of results that lead to endodontic overfills. We will look at how the literature defines overfill and overextension; attempt to address the consensus opinion on the definition of working length; and determine the effects of shaping geometry on overfill as well as the biological impact of obturation materials that go beyond the root canal space. In addition, this manuscript will highlight evidence for the prevention of overfills as well as focus on the local factors that affect repair and healing. [source] Offer and demand: proliferation and survival of neurons in the dentate gyrusEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2005Konrad Lehmann Abstract The proliferation and survival of new cells in the dentate gyrus of mammals is a complex process that is subject to numerous influences, presenting a confusing picture. We suggest regarding these processes on the level of small networks, which can be simulated in silico and which illustrate in a nutshell the influences that proliferating cells exert on plasticity and the conditions they require for survival. Beyond the insights gained by this consideration, we review the available literature on factors that regulate cell proliferation and neurogenesis in the dentate gyrus in vivo. It turns out that the rate of cell proliferation and excitatory afferents via the perforant path interactively determine cell survival, such that the best network stability is achieved when either of the two is increased whereas concurrent activation of the two factors lowers cell survival rates. Consequently, the mitotic activity is regulated by systemic parameters in compliance with the hippocampal network's requirements. The resulting neurogenesis, in contrast, depends on local factors, i.e. the activity flow within the network. In the process of cell differentiation and survival, each cell's spectrum of afferent and efferent connections decides whether it will integrate into the network or undergo apoptosis, and it is the current neuronal activity which determines the synaptic spectrum. We believe that this framework will help explain the biology of dentate cell proliferation and provide a basis for future research hypotheses. [source] Price and Volatility Transmission across BordersFINANCIAL MARKETS, INSTITUTIONS & INSTRUMENTS, Issue 3 2006Louis Gagnon Over the past forty years, financial markets throughout the world have steadily become more open to foreign investors. With open markets, asset prices are determined globally. A vast literature on portfolio choice and asset pricing has evolved to study the importance of global factors as well as local factors as determinants of portfolio choice and of expected returns on risky assets. There is growing evidence that risk premia are increasingly determined globally. An important outcome of this force of globalization is increased comovement in asset prices across markets. This survey study examines the literature on the dynamics of comovements in asset prices and volatility across markets around the world. The literature began in the 1970s in conjunction with early theoretical developments on international asset pricing models, but it blossomed in the late 1980s and early 1990s with the availability of comprehensive international stock market databases and the development of econometric methodology to model these dynamics. [source] Convergence of fish communities from the littoral zone of reservoirsFRESHWATER BIOLOGY, Issue 6 2009KEITH B. GIDO Summary 1.,Understanding factors that regulate the assembly of communities is a main focus of ecology. Human-engineered habitats, such as reservoirs, may provide insight into these assembly processes because they represent novel habitats that are subjected to colonization by fishes from the surrounding river basin or transported by humans. By contrasting community similarity within and among reservoirs from different drainage basins to nearby stream communities, we can test the relative constraints of reservoir habitats and regional species pools in determining species composition of reservoirs. 2.,We used a large spatial database that included intensive collections from 143 stream and 28 reservoir sites within three major river basins in the Great Plains, U.S.A., to compare patterns of species diversity and community structure between streams and reservoirs and to characterize variation in fish community structure within and among major drainage basins. We expected reservoir fish faunas to reflect the regional species pool, but would be more homogeneous that stream communities because similar species are stocked and thrive in reservoirs (e.g. planktivores and piscivores), and they lack obligate stream organisms that are not shared among regional species pools. 3.,We found that fish communities from reservoirs were a subset of fishes collected from streams and dominant taxa had ecological traits that would be favoured in lentic environments. Although there were regional differences in reservoir fish communities, species richness, patterns of rank abundance and community structure in reservoir communities were more homogonous across three major drainage basins than for stream communities. 4.,The general pattern of convergence of reservoir fish community structure suggests their assembly is constrained by local factors such as habitat and biotic interactions, and facilitated by the introduction of species among basins. Because there is a reciprocal transfer of biota between reservoirs and streams, understanding factors structuring both habitats is necessary to evaluate the long-term dynamics of impounded river networks. [source] Pomeranian basin (NW Poland) and its sedimentary evolution during Mississippian timesGEOLOGICAL JOURNAL, Issue 2-3 2008Hanna Matyja Abstract The Carboniferous sedimentary history of the Pomeranian Basin (NW Poland) begins with Hastarian open-marine carbonates and is terminated with ?lower Asbian terrestrial deposits in the north-eastern part and, ?upper Asbian or Brigantian, open-marine shales in the south-western part of the basin. The ?latest Viséan, Serpukhovian and early Bashkirian was a period of regional non-deposition and erosion. In the Upper Bashkirian,Gzhelian strata, an alluvial depositional environment was recognized. The Mississippian depositional history of the area has been punctuated by several, regional-scale events: (1) during the late Famennian,early Tournaisian times anoxic conditions developed over the entire basin. The results of both conodont and miospore studies show the presence of a stratigraphic gap within this sequence (which also show extremely reduced thicknesses), that comprises the uppermost Famennian (Middle and Upper praesulcata conodont zones) and the lowermost Hastarian (sulcata,sandbergi conodont zones). This stratigraphic gap probably resulted from some chemical and/or hydrodynamical factors rather than from any tectonic uplift; (2) volcanic activity on the nearby East European Craton (EEC), which was the source of large amounts of detrital (volcaniclastic) material supplied to the Pomeranian Basin during the Early crenulata,?early anchoralis-latus chrons (late Hastarian,early Ivorian), caused with time the gradual shallowing of the sedimentary environment. This shallowing trend began in the Early typicus Chron (early Ivorian) and terminated with terrestrial deposits in the early Asbian. The sedimentary succession and specific phenomena recognized in this structurally unstable basin, displays a pattern partly different from that observed in some areas in Europe. It would appear that other local factors, such as tectonic mobility of the hinterland area (EEC) and the Pomeranian Basin floor, were the possible causes of observed variations and relative sea-level changes. Copyright © 2008 John Wiley & Sons, Ltd. [source] Long-term fire frequency variability in the eastern Canadian boreal forest: the influences of climate vs. local factorsGLOBAL CHANGE BIOLOGY, Issue 5 2009ADAM A. ALI Abstract The influence of climatic and local nonclimatic factors on the fire regime of the eastern Canadian boreal forest over the last 8000 years is investigated by examining charred particles preserved in four lacustrine deposits. Herein, we compare the distribution of fire-free intervals (FFIs) and the synchronicity of fire events among sites, using Ripley's K -function to determine the extent of the role of local-scale vs. large-scale processes with respect to fire control. Between 8000 and 5800 cal. bp (calibrated years before present) the climatic and ecological conditions were less conducive to fire events than after this date. After 5800 cal. bp, the number of fires per 1000 years (fire frequency) progressively increased, reaching a maximum ca. 3400 cal. bp. There was a sharp decrease in fire frequency during the last 800 years. Between 8000 and 4000 cal. bp, comparable FFIs and synchronous fire episodes were determined for the study sites. During this period, the fire frequency was predominantly controlled by climate. After 4000 cal. bp, two sites displayed independent fire histories (different FFI distributions or asynchronous fire events), underlining the important influence of local factors, including short-term fuel wetness, characteristics of the watershed and landscape connectivity, in determining fire occurrence. We conclude that climatic changes occurred during the last 4000 years that induced a rise in the water table; this may explain the high spatial heterogeneity in fire history. Current and projected global climatic changes may cause similar spatial variability in fire frequency. [source] Global-scale patterns of nutrient resorption associated with latitude, temperature and precipitationGLOBAL ECOLOGY, Issue 1 2009Z. Y. Yuan ABSTRACT Aim Nutrient resorption from senescing leaves is an important mechanism of nutrient conservation in plants, but the patterns of nutrient resorption at the global scale are unknown. Because soil nutrients vary along climatic gradients, we hypothesize that nutrient resorption changes with latitude, temperature and precipitation. Location Global. Methods We conducted a meta-analysis on a global data set collected from published literature on nitrogen (N) and phosphorus (P) resorption of woody plants. Results For all data pooled, both N resorption efficiency (NRE) and P resorption efficiency (PRE) were significantly related to latitude, mean annual temperature (MAT) and mean annual precipitation (MAP): NRE increased with latitude but decreased with MAT and MAP. In contrast, PRE decreased with latitude but increased with MAT and MAP. When functional groups (shrub versus tree, coniferous versus broadleaf and evergreen versus deciduous) were examined individually, the patterns of NRE and PRE in relation to latitude, MAT and MAP were generally similar. Main conclusions The relationships between N and P resorption and latitude, MAT and MAP indicate the existence of geographical patterns of plant nutrient conservation strategies in relation to temperature and precipitation at the global scale, particularly for PRE, which can be an indicator for P limitation in the tropics and selective pressure shaping the evolution of plant traits. Our results suggest that, although the magnitude of plant nutrient resorption might be regulated by local factors such as substrate, spatial patterns are also controlled by temperature or precipitation. [source] Habitat influences on urban avian assemblagesIBIS, Issue 1 2009KARL L. EVANS Urbanization is increasing across the globe and there is growing interest in urban ecology and a recognition that developed areas may be important for conservation. We review the factors influencing urban avian assemblages, focusing on habitat type and anthropogenic resource provision, and analyse data from a common bird monitoring scheme to assess some of these issues. The review suggests that (1) local factors are more important than regional ones in determining the species richness of urban avian assemblages, raising the potential for the management of urban sites to deliver conservation; (2) habitat fragmentation frequently influences urban avian assemblages, with the effects of patch size being greater than those of isolation, and (3) urban bird assemblages appear to respond positively to increasing the structural complexity, species richness of woody vegetation and supplementary feeding, and negatively to human disturbance. Data from Britain's Breeding Bird Survey, combined with habitat data obtained from aerial photographs, were used to assess a number of these issues at the resolution of 1-km squares. Green-space constituted 45% of these squares, and domestic gardens contributed 50% of this green-space, though their contribution to large continuous patches of green-space was negligible. There was no significant positive correlation between the densities of individual species in urban areas and surrounding rural areas. Rural species richness declined with increasing latitude, but urban species richness was not correlated with latitude. This contrast contributes to slightly higher avian species richness in rural squares in Southern England than urban ones. Occupancy and abundance were strongly positively correlated in urban avian assemblages, and some indicator species of conservation concern occurred in few urban areas and at low densities. Such species will require conservation action to be precisely targeted within urban areas. Of the urban indicators of conservation concern, only the House Sparrow Passer domesticus and Common Starling Sturnus vulgaris were more abundant in urban than rural areas. Moreover, the densities of these two species were strongly and positively correlated, indicating that they may be limited by shared resources, such as nest-sites or supplementary food. There was little evidence that high densities of nest-predating corvids were associated with reduced densities of their prey species. Species richness and the densities of individual species frequently declined with an increasing number of buildings. Current trends for the densification of many British urban areas are thus likely to be detrimental for many bird species. [source] Interannual variability of boreal summer rainfall in the equatorial AtlanticINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 2 2009Guojun Gu Abstract Tropical Atlantic rainfall variations during boreal summer (June,July,August (JJA)) are quantified by means of a 28-year (1979,2006) monthly precipitation dataset from the Global Precipitation Climatology Project (GPCP). Rainfall variability during boreal spring (March,April,May (MAM)) is also examined for comparison in that the most intense interannual variability is usually observed during this season. Comparable variabilities in the Atlantic maritime intertropical convergence zone (ITCZ) (15° ,35°W) strength (PITCZ) are found during both seasons. Variations in the ITCZ's latitudinal location (LatITCZ) during JJA, however, are much weaker than during MAM. PITCZ and LatITCZ are shown to be closely associated with sea surface temperature (SST) anomalies in both the tropical Atlantic and Pacific. Within the tropical Atlantic, the Atlantic Niño events (Atl3) and SST anomalies in the tropical North Atlantic (TNA) are the two major local factors modulating surface rainfall patterns and variations. Atl3 is significantly correlated with PITCZ and LatITCZ during JJA and MAM. TNA is significantly correlated to PITCZ during JJA but not to LatITCZ. In contrast, TNA is significantly correlated to LatITCZ during MAM but its correlation with PITCZ is weak. The impact of the El Niño-Southern Oscillation (ENSO) events (Nino3.4) is observed during both seasons, while the correlation between Nino3.4 and LatITCZ is slightly weak. However, with the effects of Atl3 and TNA removed, the ENSO tends to have a quite limited direct impact on the tropical Atlantic, specifically over the open ocean. High second-order partial correlation between Nino3.4 and rainfall is generally confined to the western basin and over the northeastern South America. Therefore, during JJA, the two local SST modes are of dominance for the tropical Atlantic rainfall variability. Nevertheless, the ENSO seems to still play an active role in modulating surface zonal wind anomalies in the western basin and then the Atlantic Niño mode. Copyright © 2008 Royal Meteorological Society [source] Orthodontic considerations for gingival health during pregnancy: a reviewINTERNATIONAL JOURNAL OF DENTAL HYGIENE, Issue 1 2010PM Mukherjee Abstract:, Gingivitis is caused by several known systemic and local factors. Among systemic factors, the role of hormonal changes during pregnancy is well established. While presence of fixed orthodontic appliances alone may not cause gingivitis, factors such as pregnancy and poor oral hygiene combined together could precipitate acute gingival inflammation that may progress to a periodontal condition in a patient receiving orthodontic therapy. There has been an increase in the number of adult patients who are receiving orthodontic treatment. Orthodontic appliances could act as a potential plaque retentive source and aggravate inflammatory reactions that are seen during pregnancy. There is a lack of awareness regarding oral healthcare issues among patients who are pregnant and choose to seek orthodontic treatment. In addition, there is a need in the literature to outline management guidelines for patients who want to receive orthodontic treatment during pregnancy, with or without pre-existing gingival conditions. This review focuses on the aetiology of pregnancy gingivitis and the management of orthodontic patients during pregnancy. Our emphasis is on patient education, oral hygiene maintenance, preventive and treatment strategies for the management of gingival health in orthodontic patients during pregnancy. We also highlight some of the possible complications of initiating orthodontic treatment during pregnancy. [source] High incidence of demodicidosis in eyelid basal cell carcinomasINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 7 2003Zülal Erbagci MD Background Although UV radiation is the major cause of basal cell carcinoma (BCC), local factors, such as chronic trauma, irritation, or inflammation, may also have some role in its etiopathogenesis. The pilosebaceous follicle mites, Demodex folliculorum and D. brevis, inhabit most commonly and densely certain facial skin areas, including the nose and periorbital regions, where BCC also develops most frequently. Aim To investigate, in a retrospective histopathologic study, whether a possible etiopathogenetic relationship exists between demodicidosis and eyelid BCCs. Methods We examined 32 eyelid BCC specimens that contained at least five eyelashes or five hair follicles with respect to the presence and density of Demodex mites. As controls, we evaluated 34 matched specimens consisting of benign eyelid skin lesions. Results Twenty-one of 32 BCC cases (65.6%) and eight of 34 control cases (23.33%) had demodicidosis. Mean mite counts were 1.31 ± 1.57 and 0.47 ± 0.99 in BCC cases and controls, respectively. The differences were significant for both prevalence (P < 0.001) and density (P = 0.0052). Although there was a significant positive correlation between increasing mite number and patient age in the control group (r = 0.47, P < 0.05), no significant correlation was found between these two factors in BCC cases (r = ,0.102, P > 0.05). Conclusions Demodicidosis may be one of the triggering factors of carcinogenesis in eyelid BCCs in otherwise predisposed people due to its traumatic/irritating effect or chronic inflammation. [source] Macroeconomic factors and share returns: an analysis using emerging market dataINTERNATIONAL JOURNAL OF FINANCE & ECONOMICS, Issue 1 2002S.G.M. Fifield Abstract This paper investigates the extent to which global and local economic factors explain returns in emerging stock markets (ESMs). The economic factors are determined using principal components analysis. The results suggest that the local economic variables included in this study can be summarized by GDP, inflation, money and interest rates, while the selected global variables can be sufficiently characterized by world industrial production and world inflation. These components are then used as inputs into a regression analysis in order to explain the index returns of 13 ESMs over the period 1987,96. The analysis indicates that while world factors are significant in explaining ESM returns, local factors may also play a crucial role. Copyright © 2002 John Wiley & Sons, Ltd. [source] The Temporal Asynchrony of Planktonic Cladocerans Population at Different Environments of the Upper Paraná River FloodplainINTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 6 2008Erica Mayumi Takahashi Abstract The aim of this study was to investigate the existence of synchronic fluctuation patterns in cladoceran populations of the Upper Paraná River floodplain. The following hypothesis were tested: (i) the populations of a given species present the same fluctuation pattern in abundance for different environments and (ii) synchrony is higher when we consider subsets of neighboring environments or those belonging to the same category (e.g., lagoons, rivers). Samplings were performed every three months from February 2000 to November 2002 at 11 sites. To evaluate spatial synchrony, the intraclass correlation coefficient was used. The results showed no significant correlation for the most abundant species, meaning that fluctuation patterns of planktonic cladocerans were asynchronous. Asynchrony indicated that the influence of floods and regional climatic factors was not strong enough to synchronize the populations, suggesting that local factors were more important than regional effects in determining zooplankton abundance patterns. The implications of these results are that the observations from a single environment cannot be extrapolated to other environments in a manner that would allow its use as a sentinel site. This means that a monitoring program for floodplain systems, or at least for the Paraná River floodplain, has to comprise greater spatial extents. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Alveolar ridge augmentation using implants coated with recombinant human growth/differentiation factor-5: histologic observationsJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 8 2010Giuseppe Polimeni Polimeni G, Wikesjö UME, Susin C, Qahash M, Shanaman RH, Prasad HS, Rohrer MD, Hall J. Alveolar ridge augmentation using implants coated with recombinant human growth/differentiation factor-5: histologic observations. J Clin Periodontol 2010; 37: 759-768 doi: 10.1111/j.1600-051X.2010.01579.x. Abstract Objectives: In vitro and in vivo preclinical studies suggest that growth/differentiation factor-5 (GDF-5) may induce local bone formation. The objective of this study was to evaluate the potential of recombinant human GDF-5 (rhGDF-5) coated onto an oral implant with a purpose-designed titanium porous oxide surface to stimulate local bone formation including osseointegration and vertical augmentation of the alveolar ridge. Materials and Methods: Bilateral, critical-size, 5 mm, supraalveolar peri-implant defects were created in 12 young adult Hound Labrador mongrel dogs. Six animals received implants coated with 30 or 60 ,g rhGDF-5, and six animals received implants coated with 120 ,g rhGDF-5 or left uncoated (control). Treatments were alternated between jaw quadrants. The mucoperiosteal flaps were advanced, adapted, and sutured to submerge the implants for primary intention healing. The animals received fluorescent bone markers at weeks 3, 4, 7, and 8 post-surgery when they were euthanized for histologic evaluation. Results: The clinical examination showed no noteworthy differences between implants coated with rhGDF-5. The cover screw and implant body were visible/palpable through the alveolar mucosa for both rhGDF-5-coated and control implants. There was a small increase in induced bone height for implants coated with rhGDF-5 compared with the control, induced bone height averaging (±SD) 1.6±0.6 mm for implants coated with 120 ,g rhGDF-5 versus 1.2±0.5, 1.2±0.6, and 0.6±0.2 mm for implants coated with 60 ,g rhGDF-5, 30 ,g rhGDF-5, or left uncoated, respectively (p<0.05). Bone formation was predominant at the lingual aspect of the implants. Narrow yellow and orange fluorescent markers throughout the newly formed bone indicate relatively slow new bone formation within 3,4 weeks. Implants coated with rhGDF-5 displayed limited peri-implant bone remodelling in the resident bone; the 120 ,g dose exhibiting more advanced remodelling than the 60 and 30 ,g doses. All treatment groups exhibited clinically relevant osseointegration. Conclusions: rhGDF-5-coated oral implants display a dose-dependent osteoinductive and/or osteoconductive effect, bone formation apparently benefiting from local factors. Application of rhGDF-5 appears to be safe as it is associated with limited, if any, adverse effects. [source] Late-glacial and Holocene climatic effects on fire and vegetation dynamics at the prairie,forest ecotone in south-central MinnesotaJOURNAL OF ECOLOGY, Issue 5 2003Philip Camill Summary 1Treeline ecotones, such as the prairie,forest boundary, represent climatically sensitive regions where the relative abundance of vegetation types is controlled by complex interactions between climate and local factors. Responses of vegetation and fire to climate change may be tightly linked as a result of strong feedbacks among fuel production, vegetation structure and fire frequency/severity, but the importance of these feedbacks for controlling the stability of this ecotone is unclear. 2In this study, we examined the prairie,forest ecotone in south-central Minnesota using two lake sediment cores to reconstruct independent records of climate, vegetation and fire over the past 12 500 years. Using pollen, charcoal, sediment magnetic analyses and LOI properties, we investigated whether fires were controlled directly by climate or indirectly by fuel production. 3Sediment magnetic and LOI data suggest four broad climatic periods occurring c. 11 350,8250 BP (cool/humid), c. 8250,4250 BP (warm/dry), c. 4250,2450 BP (warm/humid), and c. 2450,0 BP (cool/humid), indicating that, since the mid-Holocene, climate has shifted towards wetter conditions favouring greater in-lake production and fuel production on the landscape. 4The area surrounding both lakes was characterized by boreal forest c. 12 500,10 000 BP, changing to an Ulmus-Ostrya forest c. 10 000,9000 BP, changing to a community dominated by prairie (Poaceae-Ambrosia-Artemisia) and deciduous forest taxa c. 8000,4250 BP, and finally shifting to a Quercus -dominated woodland/savanna beginning c. 4250,3000 BP. 5Charcoal influx increased from an average of 0.11,0.62 mm2 cm,2 year,1 during the early Holocene forest period (c. 11 350,8250 BP) to 1.71,3.36 mm2 cm,2 year,1 during the period of prairie expansion (c. 8250,4250 BP) and again increased to 4.18,4.90 mm2 cm,2 year,1 at the start of the woodland/savanna period (c. 4250 BP). 6As a result of the influence of climate on community composition and fuel productivity, changes in fire severity may be the result and not the cause of shifts in vegetation. [source] Multiple functions of the paranodal junction of myelinated nerve fibers,JOURNAL OF NEUROSCIENCE RESEARCH, Issue 15 2009Jack Rosenbluth Abstract Myelin sheaths include an extraordinary structure, the "paranodal axoglial junction" (PNJ), which attaches the sheath to the axon at each end of each myelin segment. Its size is enormous and its structure unique. Here we review past and current studies showing that this junction can serve multiple functions in maintaining reliable saltatory conduction. The present evidence points to three functions in particular. 1) It seals the myelin sheath to the axon to prevent major shunting of nodal action currents beneath the myelin sheath while still leaving a narrow channel interconnecting the internodal periaxonal space with the perinodal space. This pathway represents a potential route through which juxtaparanodal and internodal channels can influence nodal activity and through which nutrients, such as glucose, and other metabolites can diffuse to and from the internodal periaxonal space. 2) It serves as a mechanism for maintaining discrete, differentiated axolemmal domains at and around the node of Ranvier by acting as a barrier to the lateral movement of ion channel complexes within the axolemma, thus concentrating voltage-gated sodium channels at the node and segregating fast voltage-gated potassium channels to the juxtaparanode under the myelin sheath. 3) It attaches the myelin sheath to the axon on either side of the node and can thus maintain nodal dimensions in the face of mechanical stresses associated with stretch or other local factors that might cause disjunction. It is therefore the likely means for maintaining constancy of nodal surface area and electrical parameters essential for consistency in conduction. © 2009 Wiley-Liss, Inc. [source] Histometric evaluation of the effect of nicotine administration on periodontal breakdown: an in vivo studyJOURNAL OF PERIODONTAL RESEARCH, Issue 6 2001Francisco H. Nociti Jr The present study investigated the effect of nicotine administration on periodontal breakdown resulting from ligature-induced periodontitis in rats. Twenty adult male Wistar rats were used. After anesthesia, a mandibular first molar was randomly assigned to receive a cotton ligature in the sulcular area while the contralateral tooth was left unligated. The animals were randomly assigned to one of the following treatments, of daily intraperitoneal injections: A , saline solution, B , 0.37 mg of nicotine/kg, C , 0.57 mg of nicotine/kg and D , 0.73 mg of nicotine/kg. Thirty days later, the animals were sacrificed and the specimens routinely processed for serial decalcified sections. Statistical analysis (ANOVA) revealed greater bone loss (p<0.05) in the ligated teeth of animals which received nicotine (groups B/C/D) than in the ligated teeth of animals which received saline solution (group A). In addition, a dose-dependent response was observed among the nicotine groups. A negative effect of nicotine was observed in the unligated teeth of the experimental groups (p<0.05). Therefore, daily administration of nicotine enhanced, in a dose-dependent manner, the effects of local factors in producing periodontal breakdown. Furthermore, the nicotine seemed to have a direct deleterious effect on the periodontal tissues. [source] HABITAT DIFFERENCES IN THE TIMING OF REPRODUCTION OF THE INVASIVE ALGA SARGASSUM MUTICUM (PHAEOPHYTA, SARGASSACEAE) OVER TIDAL AND LUNAR CYCLES,JOURNAL OF PHYCOLOGY, Issue 1 2009Carla Monteiro Sargassum muticum (Yendo) Fensholt is an invasive species that is firmly established on intertidal and subtidal rocky shores of Europe and the Pacific coast of North America. Local success and spread of S. muticum is thought to rely on its reproductive potential that seems dependent on exogenous factors like tidal and lunar cycles. This study is the first to compare the reproductive patterns (periodicity of egg expulsion and embryo settlement) of this invader in two different habitats: the middle and low intertidal. The combination of monthly, daily, and tidal samples at triplicate sites within each habitat showed a semilunar periodicity of egg expulsion and embryo settlement coincident with increasing tidal amplitude just before full and new moons. In both habitats, duration of each egg expulsion event was ,1 week, and embryo settlement occurred during the first daily low tide and with the incoming high tide during spring tides. However, both expulsion and settlement started 1,2 d earlier, expulsion saturation was faster, and settlement was higher in the mid- compared to the low intertidal. Our results suggest that the exact timing of gamete expulsion and embryo release of S. muticum responds to local factors, including tidal cues, which result in differences between mid- and low-intertidal habitats. [source] Broad-scale vegetation-environment relationships in Eurasian high-latitude areasJOURNAL OF VEGETATION SCIENCE, Issue 4 2006Risto Virtanen Hultén & Fries (1986); Ignatov & Afonina (1992); Konstantinova et al. (1992); Vitikainen et al. (1997) Abstract Question: How is tundra vegetation related to climatic, soil chemical, geological variables and grazing across a very large section of the Eurasian arctic area? We were particularly interested in broad-scale vegetation-environment relationships and how well do the patterns conform to climate-vegetation schemes. Material and Methods: We sampled vegetation in 1132 plots from 16 sites from different parts of the Eurasian tundra. Clustering and ordination techniques were used for analysing compositional patterns. Vegetation-environment relationships were analysed by fitting of environmental vectors and smooth surfaces onto non-metric multidimensional scaling scattergrams. Results: Dominant vegetation differentiation was associated with a complex set of environmental variables. A general trend differentiated cold and continental areas from relatively warm and weakly continental areas, and several soil chemical and physical variables were associated with this broad-scaled differentiation. Especially soil chemical variables related to soil acidity (pH, Ca) showed linear relationships with the dominant vegetation gradient. This was closely related to increasing cryoperturbation, decreasing precipitation and cooler conditions. Remarkable differences among relatively adjacent sites suggest that local factors such as geological properties and lemming grazing may strongly drive vegetation differentiation. Conclusions: Vegetation differentiation in tundra areas conforms to a major ecocline underlain by a complex set of environmental gradients, where precipitation, thermal conditions and soil chemical and physical processes are coupled. However, local factors such as bedrock conditions and lemming grazing may cause marked deviations from the general climate-vegetation models. Overall, soil chemical factors (pH, Ca) turned out to have linear relationship with the broad-scale differentiation of arctic vegetation. [source] Regional Cluster Policies: Learning by Comparing?KYKLOS INTERNATIONAL REVIEW OF SOCIAL SCIENCES, Issue 3 2002Jan Hospers This paper deals with an intriguing paradox that can be observed in today's regional economic policy making: whereas unique local factors are increasingly seen as the determinants of regional economic success, simultaneously more and more governments try to copy policy experiences that proved to be successful in a particular region. A good example here is the use of ,best practices' in the field of regional cluster policy. Cluster programs are becoming like ,mantras' for policy makers who want to stimulate regional economic development. Given this paradox, in the present paper we address the question what lessons can be drawn from comparing success stories of regional clustering. To answer this question, we combine insights from regional economics and comparative public policy. To start, we discuss the literature that has led to the popularity of the cluster concept as a learning device among policy makers. After that, we identify the preconditions (,contingencies') that affect whether these cluster policy initiatives can be transferred from one place to another. We find that some of the contingent influences, especially those related to the degree of uniqueness of an area's economic structure and culture, hamper the possibility of ,learning by comparing' in regional cluster policy. It may even be argued that exactly those regional specificities explain the success of cluster,based policy efforts. Thus, we have to draw the rather pessimistic conclusion that the possibilities of lesson,drawing in regional cluster policy are limited. In our view, at best ,best practices' should be seen as inspiration sources rather than as recipes for successful regional economic development. A preliminary version of this paper was presented at the CURE 3,Conference on Outstanding Regions in Leeuwarden, The Netherlands, November 22,24, 2000. We would like to thank Arnoud Lagendijk, an anonymous referee and the editors for valuable comments. [source] Angiogenesis in Developing Follicle and Corpus LuteumREPRODUCTION IN DOMESTIC ANIMALS, Issue 4 2004C Tamanini Contents Angiogenesis is a process of vascular growth that is mainly limited to the reproductive system in healthy adult animals. The development of new blood vessels in the ovary is essential to guarantee the necessary supply of nutrients and hormones to promote follicular growth and corpus luteum formation. In developing follicles, the pre-existing endothelial cells that form the vascular network in the theca layer markedly develop in response to the stimulus of several growth factors, mainly produced by granulosa cells, such as vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF). The angiogenic factors also promote vessel permeability, thus favouring the antrum formation and the events inducing follicle rupture. After ovulation, newly formed blood vessels cross the basement membrane between theca and granulosa layers and continue a rapid growth to sustain corpus luteum development and function. The length of luteal vascular growth varies in cycling and pregnant animals and among species; both angiogenesis and subsequent angioregression are finely regulated by systemic and local factors. The control of angiogenic development in the ovary could be a useful tool to improve animal reproductive performances. [source] Etiology of Late Free Flap Failures Occurring After Hospital Discharge,THE LARYNGOSCOPE, Issue 11 2007Mark K. Wax MD Abstract Objectives: Vascular compromise of free flaps most commonly occurs in the immediate postoperative period in association with failure of the microvascular anastomosis. Rarely do flaps fail in the late postoperative period. It is not well understood why free flaps can fail after 7 postoperative days. We undertook a case review series to assess possible causes of late free flap failure. Study Design: Retrospective review at two tertiary referral centers: Oregon Health Sciences University and University of Alabama at Birmingham. Methods: A review of 1,530 flaps performed in 1,592 patients between 1998 and 2006 were evaluated to identify late flap failure. Late flap failure was defined as failure occurring after postoperative day 7 or on follow-up visits after hospital discharge. A prospective database with the following variables was examined: age, medical comorbidities, postreconstructive complications (fistula or infection), hematoma, seroma, previous surgery, radiation therapy, intraoperative findings at the time of debridement, nutrition, and, possibly, etiologies. Results: A total of 13 patients with late graft failure were identified in this study population of 1,530 (less than 1%) flaps; 6 radial forearm fasciocutaneous flaps, 2 rectus abdominis myocutaneous flaps, 4 fibular flaps, and 1 latissimus dorsi myocutaneous flap underwent late failure. The time to necrosis was a median of 21 (range, 7,90) days. Etiology was believed to possibly be pressure on the pedicle in the postoperative period in four patients (no sign of local wound issues at the pedicle), infection (abscess formation) in three patients, and regrowth of residual tumor in six patients. Loss occurring within 1 month was more common in radial forearm flaps and was presented in the context of a normal appearing wound at the anastomotic site, as opposed to loss occurring after 1 month, which happened more commonly in fibula flaps secondary to recurrence. Conclusion: Although late free flap failure is rare, local factors such as infection and possibly pressure on the pedicle can be contributing factors. Patients presenting with late flap failure should be evaluated for residual tumor growth. [source] Protective Effect of the Immunosuppressant Sirolimus Against Aortic Atherosclerosis In Apo E-Deficient MiceAMERICAN JOURNAL OF TRANSPLANTATION, Issue 5 2003M. Merle Elloso Atherosclerosis is a chronic inflammatory disease that develops in response to injury to the vessel wall, and is augmented by hypercholesterolemia. To further delineate the role of the immune system and local factors in this process, we assessed the effects of the immunosuppressant sirolimus (Rapamycin, RAPAMUNE®, Wyeth, Collegeville, PA) on atherosclerosis in the apoE-deficient (apoE KO) mouse, a well-accepted model of cardiovascular disease. ApoE KO mice were fed a high fat diet and sirolimus was administered. After 12 weeks, atherosclerotic lesions and plasma lipoproteins were measured. The expression of cytokines associated with atherosclerosis was also examined. All groups demonstrated plasma total cholesterol (TC) >1100 mg/dL. Sirolimus treatment was associated with a 30% increase in LDL-cholesterol (LDLc) and a dose-dependent elevation in HDL-cholesterol (HDLc). Despite increased LDLc, aortic atherosclerosis was markedly reduced in all sirolimus-treated groups. Sirolimus treatment resulted in decreased expression of IL-12p40, IFN-, and IL-10 mRNA. In contrast, TGF-,1 was elevated. Sirolimus significantly reduced atherosclerosis in apo E-KO mice; this effect is independent of, and obviates, elevated plasma TC and LDLc. Sirolimus might therefore be of benefit on atherosclerosis in patients undergoing therapy, independent of any impact on circulating lipids. [source] Roles of reactive oxygen species in the corpus luteumANIMAL SCIENCE JOURNAL, Issue 6 2006Norihiro SUGINO ABSTRACT Cells living under aerobic conditions always face the oxygen paradox. Oxygen is necessary for cells to maintain their lives. However, reactive oxygen species such as superoxide radicals, hydroxyl radicals and hydrogen peroxide are generated from oxygen and damage cells. Oxidative stress occurs as a consequence of the excessive production of reactive oxygen species and impaired antioxidant defense systems. Antioxidant enzymes include superoxide dismutase (SOD), which is a specific enzyme to scavenge superoxide radicals; copper-zinc SOD, located in the cytosol and Mn-SOD, located in the mitochondria. Both types of SOD belong to the first enzymatic step to scavenge superoxide radicals. It has been reported that a number of local factors such as cytokines, growth factors and eicosanoids are involved in the regulation of the corpus luteum (CL) function in addition to gonadotropins. Since reactive oxygen species are generated and SOD is expressed in the CL, there is a possibility that reactive oxygen species and SOD work as local regulators of the CL function. The present review reports that reactive oxygen species and their scavenging systems play important roles in the regulation of the CL function. [source] Relationship of meniscal damage, meniscal extrusion, malalignment, and joint laxity to subsequent cartilage loss in osteoarthritic kneesARTHRITIS & RHEUMATISM, Issue 6 2008Leena Sharma Objective Progressive knee osteoarthritis (OA) is believed to result from local factors acting in a systemic environment. Previous studies have not examined these factors concomitantly or compared quantitative and qualitative cartilage loss outcomes. The aim of this study was to test whether meniscal damage, meniscal extrusion, malalignment, and laxity each predicted tibiofemoral cartilage loss after controlling for the other factors. Methods Laxity and alignment were measured at baseline in individuals with knee OA. Magnetic resonance imaging included spin-echo coronal and sagittal imaging for meniscal scoring and axial and coronal spoiled gradient echo sequences with water excitation for cartilage quantification. Tibial and weight-bearing femoral condylar subchondral bone area and cartilage surface were segmented. Cartilage volume, denuded bone area, and cartilage thickness were quantified in each plate, with progression defined as cartilage loss >2 times the coefficient of variation for each plate. Qualitative outcome was assessed as worsening of the cartilage score. Logistic regression analysis with generalized estimating equations yielded odds ratios for each factor, adjusting for age, sex, body mass index, and the other factors. Results We studied 251 knees in 153 persons. After full adjustment, medial meniscal damage predicted medial tibial cartilage volume loss and tibial and femoral denuded bone increase, while varus malalignment predicted medial tibial cartilage volume and thickness loss and tibial and femoral denuded bone increase. Lateral meniscal damage predicted every lateral outcome. Laxity and meniscal extrusion had inconsistent effects. After full adjustment, no factor except medial laxity predicted qualitative outcome. Conclusion Using quantitative cartilage loss assessment, local factors that independently predicted tibial and femoral loss included medial meniscal damage and varus malalignment (medially) and lateral meniscal damage (laterally). A measurement of quantitative outcome was more sensitive at revealing these relationships than a qualitative approach. [source] | |||||||||||||||||||||||||||||||