Key Determinant (key + determinant)

Distribution by Scientific Domains
Distribution within Medical Sciences

Selected Abstracts

Globalization of the HR function: The next step in HR's transformation?

Karen Piercy
A study confirms HR's progress in moving from a transactional function to a strategic partner. The function now faces pressures to globalize by adopting service delivery models that better rationalize costs, leverage common technology and processes, and focus resources on global HR processes that can create competitive differentiation for the enterprise. The authors discuss five service delivery models along a continuum of commonality of business needs, and present four cases of global companies that found the best fit for their needs. Key determinants include financial considerations, HR service requirements, and cultural readiness. © 2008 Wiley Periodicals, Inc. [source]

Technological Scanning by Small Canadian Manufacturers

Louis Raymond
Given that in many industries new production and information technologies have fundamentally changed the way in which firms must operate and compete, the technological aspect of environmental scanning has become a critical success factor for many small and medium-sized manufacturing enterprises. As little is presently known about how technological scanning manifests itself in these organizations and about what determines the nature and level of this activity, a survey study of 324 Canadian firms was done. Testing a research model resulted in identifying four interrelated dimensions of scanning activity, namely scanning objectives, type of information, information sources, and management practices. Key determinants of this activity were also identified, including the firms' strategy, environmental uncertainty, production technology, level of R&D, information networks, and the owner-manager's education level. [source]

A comparative study of student performance in traditional mode and online mode of learning

Qiping Shen
Abstract There has been interest for many decades in comparing the effectiveness of technology-delivered instruction with traditional face-to-face teaching and measurable student outcomes have been an important indicator. Having pointed to salient aspects of the current academic environment and to some of the key literature in this area, this article analyses the performance of two groups of students studying in the traditional mode and the online mode in a masters program delivered by a Department of Computing at a university in Hong Kong. Over 2,000 students have participated in the study between 2000 and 2004. This article includes a comparison of the results between different delivery modes of study each year as well as between different classes over the 4-year period. Although traditional mode students have achieved a slightly better performance in examinations in comparison with online mode students, the article concludes that there are no significant differences in overall performance between the students. With the impact of technologies on higher education and the demands of a complex and rapidly changing society in the 21st century, this Hong Kong study contributes to the literature that finds mode of study is not a key determinant of success. © 2007 Wiley Periodicals, Inc. Comput Appl Eng Educ 15: 30,40, 2007; Published online in Wiley InterScience (; DOI 10.1002/cae.20092 [source]

Uganda: No More Pro-poor Growth?

Robert Kappel
This article explores changing growth regimes in Uganda, from pro-poor growth in the 1990s to growth without poverty reduction, actually even with a slight increase in poverty, after 2000. Not surprisingly, it finds that good agricultural performance is the key determinant of direct pro-poor growth in the 1990s, while lower agricultural growth is the root cause of the recent increase in poverty. At the same time, after 2000 low agricultural growth appears to have induced important employment shifts out of agriculture, which have dampened the increase in poverty. The article also assesses the indirect form of pro-poor growth by analysing the incidence of public spending and the tax system, and finds that indirect pro-poor growth has been achieved to only a limited extent. [source]

Two DM domain genes, DMY and DMRT1, involved in testicular differentiation and development in the medaka, Oryzias latipes

Tohru Kobayashi
Abstract The recent discovery of the DMY gene (DM domain gene on Y chromosome and one of the DMRT1 family genes) as a key determinant of male development in the medaka (Oryzias latipes) has led to its designation as the prime candidate gene for sex-determination in this species. This study focused on the sites and pattern of expression of DMY and DMRT1 genes during gonadal differentiation of medaka to further determine their roles in testis development. DMY mRNA and protein are expressed specifically in the somatic cells surrounding primordial germ cells (PGCs) in the early gonadal primordium, before morphological sex differences are seen. However, somatic cells surrounding PGCs never express DMY during the early migratory period. Expression of DMY persists in Sertoli cell lineage cells, from PGC-supporting cells to Sertoli cells, indicating that only DMY -positive cells enclose PGCs during mitotic arrest after hatching. DMRT1 is expressed in spermatogonium-supporting cells after testicular differentiation (20,30 days after hatching), and its expression is much higher than that of DMY in mature testes. In XX sex-reversed testes, DMRT1 is expressed in the Sertoli cell lineage, similar to the expression of DMY in XY testes. These results suggest strongly that DMY regulates PGC proliferation and differentiation sex-specifically during early gonadal differentiation of XY individuals and that DMRT1 regulates spermatogonial differentiation. Developmental Dynamics 231:518,526, 2004. © 2004 Wiley-Liss, Inc. [source]

Glucose homeostasis and the gastrointestinal tract: insights into the treatment of diabetes

D. Maggs
The gastrointestinal tract is increasingly viewed as a critical organ in glucose metabolism because of its role in delivering glucose to the circulation and in secreting multiple glucoregulatory hormones that, in concert with insulin and glucagon, regulate glucose homeostasis. Under normal conditions, a complex interplay of these hormones acts to maintain plasma glucose within a narrow range despite large variations in the availability of glucose, particularly during transition from the fasting to fed state. In the fed state, the rate at which nutrients are passed from the stomach to the duodenum, termed gastric emptying rate, is a key determinant of postprandial glucose flux. In patients with diabetes, the regulation of glucose metabolism is disrupted resulting in fasting and postprandial hyperglycaemia. Elucidation of the role of the gastrointestinal tract, gut-derived glucoregulatory peptides and gastric emptying rate offers a new perspective on glucose homeostasis and the respective importance of these factors in the diabetes state. This review will highlight the importance of the gastrointestinal tract in playing a key role in glucose homeostasis, particularly in the postprandial period, and the role of established or new therapies that either leverage or modify gastrointestinal function to improve glycaemic state. [source]

Gully processes and gully dynamics

M. J. Kirkby
Abstract This synthetic review of gully morphology and genesis focuses on incised semi-permanent gully systems rather than on shallow ephemeral gullies. It examines the conditions for gully formation; a sharp step to initiate a headcut, a sufficiently low effective bedload fraction to evacuate eroded material, and the potential to maintain steep sidewalls, usually dominated by mass movement processes. Gully formation is also favoured by an indurated surface layer which maintains steep sideslopes, often with armouring material from the capping layer, and a sharp headcut which does not diffuse away. Two different approaches towards the areal modelling of gully system development agree in treating the ratio of advective (channel) to diffusive (sideslope) processes as a key determinant of the morphology of a gully system as it evolves. Implications for gully prevention and remediation are briefly discussed. Copyright © 2009 John Wiley & Sons, Ltd. [source]


C. Cevik
Thromboembolism is the major chronic risk for patients with mechanical prosthetic heart valves. Although optimal oral anticoagulantion is the key determinant for embolic events (EE) in these patients; other factors also contribute to this complication. We studied the prevalence and determinants of embolic events in patients with mitral prosthetic heart valves undergoing transesophageal echocardiography (TEE). 210 patients (86 male and 124 female, mean age 45.1 +/, 9.6 years) underwent a TEE study for evaluation of prosthetic valve functions. Clinical and TEE findings of the patients were as follows: Atrial fibrillation in 132 (%62) patients, prosthetic valve thrombus in 55 (%26) suboptimal INR (INR < 1.8) in 61 (%29) pts, left atrial spontenous echocardiographic contrast (SEC) in 31 (%14) patients, paraprosthetic moderete-severe mitral regurgitation (MR) in 28 (%13), left atrial (LA) and/or left atrial appendix (LAA) thrombus in 41 (%19), LA and/or LAA outflow velocities <0.25 m/sn in 21 patiens (%10), left atrial diameter >6 cm in 47 (%22). 72 patients had a history of EE in the previous 6 months (%34). In no patients were there any EE in the presence of paraprosthetic moderate to severe MR. Both with univariate and multivariate analysis presence of prosthetic valve and LA and/or LAA thrombus, absence of paraprosthetic moderete-severe MR, suboptimal INR, atrial fibrillation were found to be independent predictors for embolic events. Conclusions: Although the presence of prosthetic valve and LA and/or LAA thrombus, suboptimal INR, and AF predict EE, clinical and echocardiographic data support the protective effect of paraprosthetic moderate to severe MR against EE in pts with mitral prosthetic valves. [source]

Liquidity in Asset Markets With Search Frictions

ECONOMETRICA, Issue 2 2009
Ricardo Lagos
We develop a search-theoretic model of financial intermediation in an over-the-counter market and study how trading frictions affect the distribution of asset holdings and standard measures of liquidity. A distinctive feature of our theory is that it allows for unrestricted asset holdings, so market participants can accommodate trading frictions by adjusting their asset positions. We show that these individual responses of asset demands constitute a fundamental feature of illiquid markets: they are a key determinant of trade volume, bid,ask spreads, and trading delays,the dimensions of market liquidity that search-based theories seek to explain. [source]

Do Peer Groups Matter?

ECONOMICA, Issue 277 2003
Peer Group versus Schooling Effects on Academic Attainment
This paper estimates an educational production function. Educational attainment is a function of peer group, parental input and schooling. Conventional measures of school quality are not good predictors for academic attainment, once we control for peer group effects; parental qualities also have strong effects on academic attainment. This academic attainment is a then a key determinant of subsequent labour market success, as measured by earnings. The main methodological innovation in this paper is the nomination of a set of instruments, very broad regions of birth, which, as a whole, pass close scrutiny for validity and permit unbiased estimation of the production function. [source]

Methods of filling root canals: principles and practices

Contemporary research points to infection control as the key determinant of endodontic success. While epidemiological surveys indicate that success is most likely in teeth which have been densely root-filled to within 2 mm of root-end, it is unclear whether the root canal filling itself is a key determinant of outcome. It is also unclear how different materials and methods employed in achieving a ,satisfactory' root filling may impact on outcome. This article provides an overview of current principles and practices in root canal filling and strives to untangle the limited and often contradictory research of relevance to clinical practice and performance. [source]

Hypolithic community shifts occur as a result of liquid water availability along environmental gradients in China's hot and cold hyperarid deserts

Stephen B. Pointing
Summary Hypolithic cyanobacterial communities occur in hot and cold hyperarid environments but the physical factors determining their diversity are not well understood. Here we report hypolithic diversity and colonization of a common quartz substrate at several hyperarid locations in the ancient deserts of north-western China, that experience varying mean annual temperature, rainfall and concomitant availability of liquid water in soil. Microscopy and enrichment culture resulted only in Chroococcidiopsis morphotypes which were ubiquitous, but community phylogenetic analysis revealed considerable cyanobacterial and heterotrophic bacterial diversity. Species Richness and Shannon's Diversity Index displayed a significant positive linear correlation with availability of liquid water but not temperature or rainfall alone. Several taxonomic groups occurred only in specific climatically defined locations, while for Chroococcidiopsis, Deinococcus and Phormidium location specific lineages within these genera were also evident. Multivariate analysis was used to illustrate pronounced community shifts due to liquid water availability, although these did not significantly affect the predicted functional relationships within any given assemblage in either hot or cold, wet or dry hyperarid deserts. This study clearly demonstrates that availability of liquid water, rather than temperature or rainfall per se is the key determinant of hypolithic diversity in hyperarid locations, and furthermore that functionally similar yet taxonomically distinct communities occur, characterized by the presence of taxa that are specific to defined levels of aridity. [source]

Potential for 4- n -nonylphenol biodegradation in stream sediments

Paul M. Bradley
Abstract The potential for in situ biodegradation of 4-nonylphenol (4-NP) was investigated in three hydrologically distinct streams impacted by wastewater treatment plants (WWTPs) in the United States. Microcosms were prepared with sediments from each site and amended with [U-ring- 14C]4- n -nonylphenol (4- n -NP) as a model test substrate. Microcosms prepared with sediment collected upstream of the WWTP outfalls and incubated under oxic conditions showed rapid and complete mineralization of [U-ring- 14C]4-n-NP to 14CO2 in all three systems. In contrast, no mineralization of [U-ring- 14C]4- n -NP was observed in these sediments under anoxic (methanogenic) conditions. The initial linear rate of [U-ring- 14C]4- n -NP mineralization in sediments from upstream and downstream of the respective WWTP outfalls was inversely correlated with the biochemical oxygen demand (BOD) of the streambed sediments. These results suggest that the net supply of dissolved oxygen to streambed sediments is a key determinant of the rate and extent of 4-NP biodegradation in stream systems. In the stream systems considered by the present study, dissolved oxygen concentrations in the overlying water column (8,10 mg/L) and in the bed sediment pore water (1,3 mg/L at a depth of 10 cm below the sediment,water interface) were consistent with active in situ 4-NP biodegradation. These results suggest WWTP procedures that maximize the delivery of dissolved oxygen while minimizing the release of BOD to stream receptors favor efficient biodegradation of 4-NP contaminants in wastewater-impacted stream environments. [source]

Organic anion-transporting polypeptide (OATP) transporter family and drug disposition

R. B. Kim
Abstract Drug transporters are increasingly recognized as a key determinant of drug disposition. Recent studies have revealed that targeted expression of drug uptake and efflux transporters to specific cell membrane domains allows for the efficient directional movement of many drugs in clinical use. While the role of certain efflux transporters such as MDR1 (P-glycoprotein) in drug disposition has been extensively studied, emerging evidence suggests that uptake transporters may also be important to the intestinal absorption and renal or hepatic elimination of drugs. Members of the organic anion-transporting polypeptide (OATP) family of drug uptake transporters have been found capable of transporting a large array of structurally divergent drugs. Moreover, expression of OATP isoforms in the gastrointestinal tract, liver and kidney, as well as at the level of the blood,brain barrier, has important implications for our understanding of the factors governing drug absorption, elimination and tissue penetration. [source]

Red hair, fair skin and melanoma , melanocortin 1 receptor

J. L. Rees
We have previously shown that the MC1R is a key determinant of pigmentary phenotype in man. A range of common and uncommon alleles show diminished function leading to a change in the relative amounts of eumelanin and pheomelanin. As expected, these particular allelic variants are associated with both non-melanoma and melanoma skin cancer and other pigmentary phenotypic characteristics such as freckling. We have recently shown that even against very different genetic backgrounds, the MC1R variants show a phenotypic effect [J Invest Dermatol 2003: 121 (1): 207]. We will present data to explain how the human pigmentary phenotypes can be quantified more appropriately, in terms of both hair melanins and cutaneous response to ultraviolet radiation (submitted and in press). Our results, we would argue, are relevant to those interested in melanocortin signalling in skin and to studies of the genetics of human skin colour and evolution of skin colour. [source]

Soil parent material is a key determinant of the bacterial community structure in arable soils

Andreas Ulrich
Abstract The bacterial community composition in soil and rhizosphere taken from arable field sites, differing in soil parent material and soil texture, was analyzed using terminal restriction fragment length polymorphism (T-RFLP) of 16S rRNA genes. Nine sandy to silty soils from North-East Germany could clearly be distinguished from each other, with a relatively low heterogeneity in the community structure within the field replicates. There was a relationship between the soil parent material, i.e. different glacial and aeolian sediments, and the clustering of the profiles from different sites. A site-specific grouping of T-RFLP profiles was also found for the rhizosphere samples of the same field sites that were planted with potatoes. The branching of the rhizosphere profiles corresponded partly with the soil parent material, whereas the effect of the plant genotype was negligible. Selected terminal restriction fragments differing in their relative abundance within the nine soils were analyzed based on the cloning of the 16S rRNA genes of one soil sample. A high phylogenetic diversity observed to include Acidobacteria, Betaproteobacteria, Bacteroidetes, Verrucomicrobia, and Gemmatimonadetes. The assignment of three out of the seven selected terminal restriction fragments to members of Acidobacteria suggested that this group seems to participate frequently in the shifting of community structures that result from soil property changes. [source]

Habitat selection and diel distribution of the crustacean zooplankton from a shallow Mediterranean lake during the turbid and clear water phases

Summary 1. The fish fauna of many shallow Mediterranean Lakes is dominated by small-bodied exotic omnivores, with potential implications for fish,zooplankton interactions still largely unknown. Here we studied diel variation in the vertical and horizontal distribution of the crustacean plankton in Lake Vela, a shallow polymictic and eutrophic lake. Diel sampling was carried out on three consecutive days along a horizontal transect, including an open-water station and a macrophyte (Nymphaea alba) bed. Since transparency is a key determinant of the predation risk posed by fish, the zooplankton sampling campaigns were conducted in both the turbid (autumn) and clear water (spring) phases. 2. In the turbid phase, most taxa were homogeneously distributed along the vertical and horizontal axes in the three consecutive days. The only exception was for copepod nauplii, which showed vertical heterogeneity, possibly as a response to invertebrate predators. 3. In the clear water phase, most zooplankton taxa displayed habitat selection. Vertically, the general response consisted of a daily vertical migration (DVM), despite the limited depth (1.6 m). Horizontally, zooplankters showed an overall preference for the pelagic zone, independent of the time of the day. Such evidence is contrary to the postulated role of macrophytes as an anti-predator refuge for the zooplankton. 4. These vertical (DVM) and horizontal (macrophyte-avoidance) patterns were particularly conspicuous for large Daphnia, suggesting that predation risk from size-selective predators (fish) was the main factor behind the spatial heterogeneity of zooplankton in the spring. Thus, the difference in the zooplankton spatial distribution pattern and habitat selection among seasons (turbid and clear water phases) seems to be mediated the predation risk from fish, which is directly related to water transparency. 5. The zooplankton in Lake Vela have anti-predator behaviour that minimises predation from fish. We hypothesise that, due to the distinct fish community of shallow Mediterranean lakes, aquatic macrophytes may not provide adequate refuge to zooplankters, as seen in northern temperate lakes. [source]

Factors Associated With Burden of Primary Headache in a Specialty Clinic

HEADACHE, Issue 6 2003
Eugene M. Cassidy MRCPsych
Objective.,To examine factors associated with social, occupational, and psychological burden of common primary headache (migraine and tension-type headache). Background.,The personal and social burden of primary headache is high. Health, occupational, social, and psychological factors contributing to burden in people with disabling headache have not been fully unravelled. Methods.,One hundred eighty consecutive patients with either migraine or tension-type headache attending a specialty headache outpatient clinic for the first time were evaluated over a 9-month period. Headache subtype was operationally defined according to International Headache Society criteria. Headache frequency, duration, and severity were recorded. Occupational and social disability were quantified using the Migraine Disability Assessment questionnaire. Psychological burden was quantified using the 28-item General Health Questionnaire, the Beck Depression Inventory, and the State-Trait Anxiety Inventory. Premorbid vulnerability to life stress was quantified using the neuroticism subscale of the Eysenck Personality Inventory. Results.,Patients with frequent (chronic) headache scored higher on the Migraine Disability Assessment questionnaire and had higher Beck Depression Inventory and General Health Questionnaire depression scores than those with less frequent (episodic) headache. Frequency of headache, but not pain severity, duration, or diagnosis, predicted both Migraine Disability Assessment total disability and General Health Questionnaire/Beck Depression Inventory depression. Neuroticism was predictive of depression but not disability. Patients with chronic migraine had the highest depression and disability scores. Conclusion.,The number of days per month with headache is a key determinant of headache-related burden in those attending specialty clinics. Frequent (chronic) headache is associated with significantly higher psychopathology scores and general social impairment, but the direction of this relationship is not clear. Those with migraine and chronicity are the most impaired. [source]

On the effects of triangulated terrain resolution on distributed hydrologic model response

Enrique R. Vivoni
Abstract Distributed hydrologic models based on triangulated irregular networks (TIN) provide a means for computational efficiency in small to large-scale watershed modelling through an adaptive, multiple resolution representation of complex basin topography. Despite previous research with TIN-based hydrology models, the effect of triangulated terrain resolution on basin hydrologic response has received surprisingly little attention. Evaluating the impact of adaptive gridding on hydrologic response is important for determining the level of detail required in a terrain model. In this study, we address the spatial sensitivity of the TIN-based Real-time Integrated Basin Simulator (tRIBS) in order to assess the variability in the basin-averaged and distributed hydrologic response (water balance, runoff mechanisms, surface saturation, groundwater dynamics) with respect to changes in topographic resolution. Prior to hydrologic simulations, we describe the generation of TIN models that effectively capture topographic and hydrographic variability from grid digital elevation models. In addition, we discuss the sampling methods and performance metrics utilized in the spatial aggregation of triangulated terrain models. For a 64 km2 catchment in northeastern Oklahoma, we conduct a multiple resolution validation experiment by utilizing the tRIBS model over a wide range of spatial aggregation levels. Hydrologic performance is assessed as a function of the terrain resolution, with the variability in basin response attributed to variations in the coupled surface,subsurface dynamics. In particular, resolving the near-stream, variable source area is found to be a key determinant of model behaviour as it controls the dynamic saturation pattern and its effect on rainfall partitioning. A relationship between the hydrologic sensitivity to resolution and the spatial aggregation of terrain attributes is presented as an effective means for selecting the model resolution. Finally, the study highlights the important effects of terrain resolution on distributed hydrologic model response and provides insight into the multiple resolution calibration and validation of TIN-based hydrology models. Copyright © 2005 John Wiley & Sons, Ltd. [source]

The perceived credibility of quality labels: a scale validation with refinement

Salim Moussa
Abstract In this paper, we present quality labels as signals that reduce problems that arise under asymmetric information. We propose to closely scrutinize the concept of signal credibility, which is a key determinant of signalling effectiveness. In order to assess the perceived credibility of a quality label, we offer a revisited version of a scale originally proposed by Larceneux. The data used in this paper involve three different labels and were collected using self-report surveys administered to 602 respondents. Based on findings from a variety of reliability and validity tests, the scale demonstrates good psychometric properties. Both theoretical and managerial implications are discussed, along with limitations and future research directions. [source]

Human MHC architecture and evolution: implications for disease association studies

J. A. Traherne
Summary Major histocompatibility complex (MHC) variation is a key determinant of susceptibility and resistance to a large number of infectious, autoimmune and other diseases. Identification of the MHC variants conferring susceptibility to disease is problematic, due to high levels of variation and linkage disequilibrium. Recent cataloguing and analysis of variation over the complete MHC has facilitated localization of susceptibility loci for autoimmune diseases, and provided insight into the MHC's evolution. This review considers how the unusual genetic characteristics of the MHC impact on strategies to identify variants causing, or contributing to, disease phenotypes. It also considers the MHC in relation to novel mechanisms influencing gene function and regulation, such as epistasis, epigenetics and microRNAs. These developments, along with recent technological advances, shed light on genetic association in complex disease. [source]

The determinants of export performance: A review of the research in the literature between 1998 and 2005

Carlos M.P. Sousa
Considerable attention has been paid to the determinants of export performance. However, despite this research effort in identifying and examining the influence of such determinants, the literature is characterized by fragmentation and diversity, hindering theory development and practical advancement in the field. This paper attempts to review and synthesize the knowledge on the subject. As a result, this study reviews and evaluates 52 articles published between 1998 and 2005 to assess the determinants of export performance. The assessment reveals that: (a) more studies have been conducted outside the USA; (b) the majority of the studies focus on manufacturing firms, with relatively few studies examining the service sector; (c) the majority of the export studies continue to focus on small to medium-sized firms; (d) there is a continuous increase in the sample size; (e) despite the problems that may arise from the use of single informants, it seems that none of the studies reviewed here collected data from more than one informant in the firm; (f) an increasing number of studies have been using the export venture as the unit of analysis; (g) the level of statistical sophistication has improved; (h) the use of control and moderating variables in export performance studies has increased; (i) more studies have started to include the external environment in their models, including domestic market characteristics; and (j) market orientation as a key determinant of export performance emerges in this review. Finally, conclusions are drawn, along with some suggestions for further research. [source]

Search strategies in decision making: the success of "success"

Ben R. Newell
Abstract Examination of search strategies has tended to focus on choices determined by decision makers' personal preferences among relevant cues, and not on learning cue-criterion relationships. We present an empirical and rational analysis of cue search for environments with objective criteria. In such environments, cues can be evaluated on the basis of three properties: validity (the probability that a cue identifies the correct choice if cue values differ between alternatives); discrimination rate (the proportion of occasions on which a cue has differing values); and success (the expected proportion of correct choices when only that cue can be used). Our experiments show that though there is a high degree of individual variability, success is a key determinant of search. Furthermore, a rational analysis demonstrates why success-directed search is the most adaptive strategy in many circumstances. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Osteoblast-Specific Targeting of Soluble Colony-Stimulating Factor-1 Increases Cortical Bone Thickness in Mice,,

SL Abboud
Abstract The soluble and membrane-bound forms of CSF-1 are synthesized by osteoblasts and stromal cells in the bone microenvironment. Transgenic mice, generated to selectively express sCSF-1 in bone, showed increased cortical thickness in the femoral diaphysis caused by new bone formation along the endosteal surface. The ability of sCSF-1 to enhance bone cell activity in vivo is potentially relevant for increasing cortical bone in a variety of disorders. Introduction: The soluble form of colony-stimulating factor-1 (sCSF-1) and the membrane-bound form of CSF-1 (mCSF-1) have been shown to support osteoclastogenesis in vitro; however, the effect of each peptide on bone remodeling in vivo is unclear. To determine the effect of sCSF-1, selectively expressed in bone, the skeletal phenotype of transgenic mice harboring the human sCSF-1 cDNA under the control of the osteocalcin promoter was assessed. Methods: At 5 and 14 weeks, mice were analyzed for CSF-1 protein levels, weighed, and X-rayed, and femurs were removed for peripheral quantitative computed tomography, histology, and histomorphometry. Results: High levels of human sCSF-1 were detected in bone extracts and, to a lesser extent, in plasma. Adult transgenic mice showed normal body weight and increased circulating monocytic cells. At 5 weeks, the femoral diaphysis was similar in CSF-1T and wt/wt littermates. However, by 14 weeks, the femoral diaphysis in CSF-1T mice showed increased cortical thickness and bone mineral density. In contrast to the diaphysis, the femoral metaphysis of CSF-1T mice showed normal cancellous bone comparable with wt/wt littermates at each time point. Histological sections demonstrated increased woven bone along the endosteal surface of the diaphysis and intracortical remodeling. Fluorochrome-labeling analysis confirmed endocortical bone formation in CSF-1T, with a 3.1-fold increase in the percentage of double-labeled surfaces and a 3.6-fold increase in the bone formation rate compared with wt/wt mice. Although remodeling resulted in a slightly porous cortex, sCSF-1 preferentially stimulated endocortical bone formation, leading to increased cortical thickness. Conclusions: These findings indicate that sCSF-1 is a key determinant of bone cell activity in the corticoendosteal envelope. [source]

C-terminal 37 residues of LRP promote the amyloidogenic processing of APP independent of FE65

Madepalli K. Lakshmana
Abstract The major defining pathological hallmark of Alzheimer's disease (AD) is the accumulation of amyloid , protein (A,), a small peptide derived from ,- and ,-secretase cleavages of the amyloid precursor protein (APP). Recent studies have shown that the Low-density lipoprotein receptor-related protein (LRP) plays a pivotal role in the trafficking of APP and generation of A,. In particular, we recently showed that the soluble cytoplasmic tail of LRP (LRP-ST) without a membrane tether was sufficient to promote A, generation. In this study, we demonstrate that the last 37 residues of LRP cytoplasmic tail (LRP-C37) lacking the NPxY motifs and FE65 binding mediate the core pro-amyloidogenic activity of LRP-ST. Moreover, we show that the conserved dileucine motif within the LRP-C37 region is a key determinant of its A, promoting activity. Finally, results from a yeast two-hybrid screen using LRP-C37 region as bait reveal four new LRP-binding proteins implicated in intracellular signalling and membrane protein trafficking. Our findings indicate that the LRP-C37 sequence represents a new protein-binding domain that may be useful as a therapeutic target and tool to lower A, generation in AD. [source]

Membrane bioreactors vs conventional biological treatment of landfill leachate: a brief review

Héctor Alvarez-Vazquez
Abstract A review of quality and biological treatment of landfill leachate is presented. Conventional ex-situ treatment normally demands multistage process treatment schemes, which may encompass both aerobic and anaerobic technologies alongside chemical precipitation and/or oxidation. This is to be contrasted with the more recent membrane bioreactor technology, which generally demands much reduced pre- and post-treatment and has a much reduced footprint compared with conventional biotreatment. Results are summarised in terms of the key determinant of COD removal for waters characterised in terms of BOD/COD ratio and age. Process operation is characterised with respect to COD strength and loading rate, hydraulic retention time and number of individual unit operations. Copyright © 2004 Society of Chemical Industry [source]

The efficiency of mitochondrial electron transport chain is increased in the long-lived mrg19 Saccharomyces cerevisiae

AGING CELL, Issue 6 2009
Nitish Mittal
Summary Integrity of mitochondrial functionality is a key determinant of longevity in several organisms. In particular, reduced mitochondrial ROS (mtROS) production leading to decreased mtDNA damage is believed to be a crucial aspect of longevity. The generation of low mtROS was thought to be due to low mitochondrial oxygen consumption. However, recent studies have shown that higher mitochondrial oxygen consumption could still result in low mtROS and contribute to longevity. This increased mitochondrial efficiency (i.e. low mtROS generated despite high oxygen consumption) was explained as a result of mitochondrial biogenesis, which provides more entry points for the electrons to the electron transport chain (ETC), thereby resulting in low mtROS production. In this study, we provide evidence for the existence of an alternative pathway to explain the observed higher mitochondrial efficiency in the long-lived mrg19 mutant of Saccharomyces cerevisiae. Although we observe similar amounts of mitochondria in mrg19 and wild-type (wt) yeast, we find that mrg19 mitochondria have higher expression of ETC components per mitochondria in comparison with the wt. These findings demonstrate that more efficient mitochondria because of increased ETC per mitochondria can also produce less mtROS. Taken together, our findings provide evidence for an alternative explanation for the involvement of higher mitochondrial activity in prolonging lifespan. We anticipate that similar mechanisms might also exist in eukaryotes including human. [source]

Long-term effects of calorie or protein restriction on serum IGF-1 and IGFBP-3 concentration in humans

AGING CELL, Issue 5 2008
Luigi Fontana
Summary Reduced function mutations in the insulin/IGF-I signaling pathway increase maximal lifespan and health span in many species. Calorie restriction (CR) decreases serum IGF-1 concentration by ~40%, protects against cancer and slows aging in rodents. However, the long-term effects of CR with adequate nutrition on circulating IGF-1 levels in humans are unknown. Here we report data from two long-term CR studies (1 and 6 years) showing that severe CR without malnutrition did not change IGF-1 and IGF-1 : IGFBP-3 ratio levels in humans. In contrast, total and free IGF-1 concentrations were significantly lower in moderately protein-restricted individuals. Reducing protein intake from an average of 1.67 g kg,1 of body weight per day to 0.95 g kg,1 of body weight per day for 3 weeks in six volunteers practicing CR resulted in a reduction in serum IGF-1 from 194 ng mL,1 to 152 ng mL,1. These findings demonstrate that, unlike in rodents, long-term severe CR does not reduce serum IGF-1 concentration and IGF-1 : IGFBP-3 ratio in humans. In addition, our data provide evidence that protein intake is a key determinant of circulating IGF-1 levels in humans, and suggest that reduced protein intake may become an important component of anticancer and anti-aging dietary interventions. [source]

Gender and collective action: motivations, effectiveness and impact

Lauren Pandolfelli
Abstract Gender is often a key determinant of people's abilities to participate in collective action, yet there has been relatively little research on the links between gender and collective action. This article, and the ones that follow in this special issue, explore the intersection of these two fields. We present three entry points for a gendered analysis of collective action: motivations to engage in collective action; effectiveness of collective action (as defined by group objectives and the process by which the group works to meet those objectives); and impact of collective action on gender equity. We discuss each of these themes by highlighting key issues presented in the articles in this special issue. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Firm-level Disclosures and the Relative Roles of Culture and Legal Origin

Ole-Kristian Hope
In this paper, I investigate the relative roles of legal origin and national culture in explaining firm-level disclosure levels internationally. Using a significantly larger and more representative sample than prior research, I document, using univariate and multivariate analyses, that both legal origin and culture (as operationalized by Hofstede and Schwartz) are important in explaining firm disclosure. Neither legal origin nor culture dominates with respect to overall explanatory power for variations in disclosure levels. Consequently, it is premature to write off culture as an important factor in the financial reporting environment. Furthermore, I find that legal origin is an important conditioning variable for the role of culture. Finally, although legal origin is a key determinant of disclosure levels, I hypothesize and find that its importance decreases with the richness of a firm's information environment. [source]