Distribution by Scientific Domains
Distribution within Life Sciences

Terms modified by Unresolved

  • unresolved issue
  • unresolved issues
  • unresolved loss
  • unresolved problem
  • unresolved question

  • Selected Abstracts

    Maternal unresolved attachment status impedes the effectiveness of interventions with adolescent mothers

    Greg Moran
    Children of adolescent mothers are at risk for a variety of developmental difficulties. In the present study, the effectiveness of a brief intervention program designed to support adolescent mothers' sensitivity to their infants' attachment signals was evaluated. Participants were adolescent mothers and their infants who were observed at 6, 12, and 24 months of age. The intervention conducted by clinically trained home visitors consisted of eight home visits between 6 and 12 months in which mothers were provided feedback during the replay of videotaped play interactions. At 12 months, 57% of the mother,infant dyads in the intervention group and 38% of the comparison group dyads were classified as secure in the Strange Situation. Seventy-six percent of the mothers in the intervention group maintained sensitivity from 6 to 24 months compared with 54% of the comparison mothers. Further analyses indicated that the intervention was effective primarily for mothers who were not classified as Unresolved on the Adult Attachment Interview. [source]

    Cardiovascular function in the heat-stressed human

    ACTA PHYSIOLOGICA, Issue 4 2010
    C. G. Crandall
    Abstract Heat stress, whether passive (i.e. exposure to elevated environmental temperatures) or via exercise, results in pronounced cardiovascular adjustments that are necessary for adequate temperature regulation as well as perfusion of the exercising muscle, heart and brain. The available data suggest that generally during passive heat stress baroreflex control of heart rate and sympathetic nerve activity are unchanged, while baroreflex control of systemic vascular resistance may be impaired perhaps due to attenuated vasoconstrictor responsiveness of the cutaneous circulation. Heat stress improves left ventricular systolic function, evidenced by increased cardiac contractility, thereby maintaining stroke volume despite large reductions in ventricular filling pressures. Heat stress-induced reductions in cerebral perfusion likely contribute to the recognized effect of this thermal condition in reducing orthostatic tolerance, although the mechanism(s) by which this occurs is not completely understood. The combination of intense whole-body exercise and environmental heat stress or dehydration-induced hyperthermia results in significant cardiovascular strain prior to exhaustion, which is characterized by reductions in cardiac output, stroke volume, arterial pressure and blood flow to the brain, skin and exercising muscle. These alterations in cardiovascular function and regulation late in heat stress/dehydration exercise might involve the interplay of both local and central reflexes, the contribution of which is presently unresolved. [source]

    Corporate social responsibility and the identification of stakeholders

    Janita F. J. Vos
    As a management problem the identification of stakeholders is not easily solved. It comprises a modelling and a normative issue, which need to be solved in connection with each other. In stakeholder literature knowledge can be found, e.g. on various stakeholder categorizations, that could be useful for the modelling issue. However, the normative issue remains unresolved. Additionally, the modelling of the so-called stakeholder category ,the affected' further complicates this issue. Nevertheless, from a normative perspective, this group holds justified interests in aspects of organizational activity and its members are, for that reason, legitimate stakeholders. In this article it is explored to what extent critical systems heuristics can help in resolving the managerial problem of identifying stakeholders. Critical systems heuristics is a modelling methodology in which the normative aspect of modelling is crucial. Using the distinction between ,the involved' and ,the affected', a variety of boundary judgments are discussed. Special attention is given to the so-called ,witness' as a representative of the affected. Copyright © 2003 John Wiley & Sons, Ltd and ERP Environment. [source]

    A Model for Evaluating Organizational Competencies: An Application in the Context of a Quality Management Initiative,

    DECISION SCIENCES, Issue 2 2005
    Ana Belén Escrig-Tena
    ABSTRACT Despite the important contributions made by the Competency-Based Perspective (CBP) to strategic thought, certain issues on the operational definition of the theoretical concepts that characterize this approach remain unresolved, thus limiting its empirical application. In addressing this issue, the present study puts forward a procedure for measuring the competencies that can be developed in association with a Quality Management (QM) initiative and analyzes the reliability and validity of the resulting scale. This procedure could be transferred to studies that aim to carry out an empirical analysis based on the theoretical position of the CBP. [source]

    Scaling Up AIDS Treatment in Developing Countries: A Review of Current and Future Arguments

    Jens Kovsted
    Until recently, antiretroviral treatment against AIDS was perceived to be beyond the reach of the majority of patients in developing countries. This situation has changed drastically as international funding for AIDS treatment has swelled to several billion dollars a year. What has brought about this change? Analysis of the merit of six arguments often put forward against scaling up AIDS treatment in developing countries makes it clear that the most significant (and perhaps only) real change has been the large reduction in the price of the drugs. Although affordability is obviously a central issue, it is noticeable that most of the remaining arguments continue to be unresolved. This underlines the dangers of proceeding too fast towards treatment goals. [source]

    Neighbour-regulated mortality: the influence of positive and negative density dependence on tree populations in species-rich tropical forests

    ECOLOGY LETTERS, Issue 8 2003
    Halton A. Peters
    Abstract Density-dependent mortality has long been posited as a possible mechanism for the regulation of tropical forest tree density. Despite numerous experimental and phenomenological investigations, the extent to which such mechanisms operate in tropical forests remains unresolved because the demographical signature of density dependence has rarely been found in extensive investigations of established trees. This study used an individual-based demographical approach to investigate the role of conspecific and heterospecific neighbourhood crowding on tree mortality in a Panamanian and a Malayan tropical forest. More than 80% of the species investigated at each site were found to exhibit density-dependent mortality. Furthermore, most of these species showed patterns of mortality consistent with the Janzen,Connell hypothesis and the rarely explored hypothesis of species herd protection. This study presents some of the first evidence of species herd protection operating in tree communities. [source]

    Changes in Panayiotopoulos syndrome over time

    EPILEPSIA, Issue 2009
    Giuseppe Capovilla
    Summary In its first description (1989), Panayiotopoulos syndrome was defined as an idiopathic epilepsy syndrome with an excellent prognosis, characterized by a clinical ictal triad of nocturnal seizures, tonic deviation of the eyes, and vomiting. The electroencephalographic and clinical features of this condition were highly suggestive of occipital lobe involvement. Subsequently, the concept of this benign age-related focal epilepsy has been expanded over the years, including a wider and larger spectrum of seizure manifestations far beyond the occipital manifestations, and for which the eponym of Panayiotopoulos syndrome (PS) has been adopted. However, many theoretical and practical points, including diagnostic, genetic, and pathophysiologic issues remain still unresolved for PS. [source]

    Mate Choice for Genetic Benefits: Time to Put the Pieces Together

    ETHOLOGY, Issue 1 2010
    Attila Hettyey
    It is thought that mate choice allows individuals to obtain genetic benefits for their offspring, and although many studies have found some support for this hypothesis, several critical questions remain unresolved. One main problem is that empirical studies on mate choice and genetic benefits have been rather piecemeal. Some studies (1) aimed to test how mate choice affects offspring fitness, but have not examined whether the benefits are because of genetic effects. Other studies tested whether mate choice provides (2) additive or (3) non-additive genetic benefits and only a few studies (4) considered these genetic effects together. Finally, some studies (5) examined whether the potential benefits that might be gained from mate choice are due to additive genetic effects vs. non-additive effects, and although they found evidence for both, they did not examine whether mate choice is relevant. Furthermore, previous studies have usually not controlled for non-genetic sources of variation in offspring fitness. Thus, there remain gaping holes in our understanding, and it is the connections among the research approaches that now need more attention. We suggest that studies are needed that measure non-genetic effects, the potential benefits from both additive and non-additive genetic effects, and also determine whether mate choice exploits these potential benefits. Such integrative studies are necessary to put the pieces together and clarify the role of genetic benefits in the evolution of mate choice. [source]

    APRIL (TNFSF13) regulates collagen-induced arthritis, IL-17 production and Th2 response

    Yanping Xiao
    Abstract A proliferation-inducing ligand (APRIL or TNFSF13) shares receptors with B-cell activation factor of the TNF family (BAFF) on B and T cells. Although much is known about the function of APRIL in B cells, its role in T cells remains unclear. Blocking both BAFF and APRIL suggested that BAFF and/or APRIL contributed to collagen-induced arthritis (CIA); however, the role of APRIL alone in CIA remained unresolved. We show here that, in vitro, our newly generated APRIL,/, mice exhibited increased T-cell proliferation, enhanced Th2 cytokine production under non-polarizing conditions, and augmented IL-13 and IL-17 production under Th2 polarizing conditions. Upon immunization with OVA and aluminum potassium sulfate, APRIL,/, mice responded with an increased antigen-specific IgG1 response. We also show that in APRIL,/, mice, the incidence of CIA was significantly reduced compared with WT mice in parallel with diminished levels of antigen-specific IgG2a autoantibody and IL-17 production. Our data indicate that APRIL plays an important role in the regulation of cytokine production and that APRIL-triggered signals contribute to arthritis. Blockade of APRIL thus may be a valuable adjunct in the treatment of rheumatoid arthritis. [source]

    Paucity of enkephalin production in neostriatal striosomal neurons: analysis with preproenkephalin,green fluorescent protein transgenic mice

    Yoshinori Koshimizu
    Abstract Whether or not the striosome compartment of the neostriatum contained preproenkephalin (PPE)-expressing neurons remained unresolved. To address this question by developing a sensitive detection method, we generated transgenic mice expressing enhanced green fluorescent protein (GFP) under the specific transcriptional control of the PPE gene. Eight transgenic lines were established, and three of them showed GFP expression which was distributed in agreement with the reported localization of PPE mRNA in the central nervous system. Furthermore, in the matrix compartment of the neostriatum of the three lines, intense GFP immunoreactivity was densely distributed in the neuronal cell bodies and neuropil, and matrix neurons displayed > 94% co-localization for GFP and PPE immunoreactivities. In sharp contrast, GFP immunoreactivity was very weak in the striosome compartment, which was characterized by intense immunoreactivity for mu-opioid receptors (MOR). Although neostriatal neurons were divided into GFP-immunopositive and -negative groups in both the striosome and matrix compartments, GFP immunoreactivity of cell bodies was much weaker (,1/5) in GFP-positive striosomal neurons than in GFP-positive matrix neurons. A similar reciprocal organization of PPE and MOR expression was also suggested in the ventral striatum, because GFP immunoreactivity was weaker in intensely MOR-immunopositive regions than in the surrounding MOR-negative regions. As PPE-derived peptides are endogenous ligands for MOR in the neostriatum and few axon collaterals of matrix neurons enter the striosome compartment, the present results raised the question of the target of those peptides produced abundantly by matrix neurons. [source]

    Differential cortical activity for precision and whole-hand visually guided grasping in humans

    Chiara Begliomini
    Abstract Effective grasping involves the remarkable ability to implement multiple grasp configurations such as precision grip (PG; opposition between the index finger and thumb) and whole-hand grasp (WHG), depending on the properties of the object grasped (e.g. size, shape and weight). In the monkey brain, different groups of cells in the anterior,lateral bank of the intraparietal sulcus (area AIP) are differentially active for various hand configurations during grasping of differently shaped objects. Visually guided grasping studies in humans suggest the anterior intraparietal sulcus (aIPS) as the homologue of macaque area AIP, but leave unresolved the question of whether activity in human aIPS reflects the relationship between object size and grasp configuration, as in macaques. To address this issue, a human fMRI study was conducted in which objects were grasped with the right hand while object size was varied. The results indicated that the left aIPS was active when the subjects naturally adopted a PG to grasp the small object but showed a much weaker response when subjects naturally adopted a WHG to grasp the large object. The primary motor cortex and somatosensory cortices were active for both PG and WHG. Our results suggest that, in humans, the aIPS is centrally involved in determining the type of grasp. [source]

    Visualization of corticofugal projections during early cortical development in a ,-GFP-transgenic mouse

    Erin C. Jacobs
    Abstract The first postmitotic neurons in the developing neocortex establish the preplate layer. These early-born neurons have a significant influence on the circuitry of the developing cortex. However, the exact timing and trajectory of their projections, between cortical hemispheres and intra- and extra-cortical regions, remain unresolved. Here, we describe the creation of a transgenic mouse using a 1.3 kb golli promoter element of the myelin basic protein gene to target expression of a ,,green fluorescent protein (GFP) fusion protein in the cell bodies and processes of pioneer cortical neurons. During embryonic and early neonatal development, the timing and patterning of process extension from these neurons was examined. Analysis of ,-GFP fluorescent fibers revealed that progression of early labeled projections was interrupted unexpectedly by transient pauses at the corticostriatal and telencephalic,diencephalic boundaries before invading the thalamus just prior to birth. After birth the pioneering projections differentially invaded the thalamus, excluding some nuclei, e.g. medial and lateral geniculate, until postnatal days 10,14. Early labeled projections were also found to cross to the contralateral hemisphere as well as to the superior colliculus. These results indicate that early corticothalamic projections appear to pause before invading specific subcortical regions during development, that there is developmental regulation of innervation of individual thalamic nuclei, and that these early-generated neurons also establish early projections to commissural and subcortical targets. [source]

    Effect of auditory cortex lesions on the discrimination of frequency-modulated tones in rats

    Natalia Rybalko
    Abstract The lateralization of functions to individual hemispheres of the mammalian brain remains, with the exception of the human brain, unresolved. The aim of this work was to investigate the ability to discriminate between falling and rising frequency-modulated (FM) stimuli in rats with unilateral or bilateral lesions of the auditory cortex (AC). Using an avoidance conditioning procedure, thirsty rats were trained to drink in the presence of a rising FM tone and to stop drinking when a falling FM tone was presented. Rats with a lesion of the AC were able to learn to discriminate between rising and falling FM tones; however, they performed significantly worse than did control rats. A greater deficit in the ability to discriminate the direction of frequency modulation was observed in rats with a right or bilateral AC lesion. The discrimination performance (DP) in these rats was significantly worse than the DP in rats with a left AC lesion. Animals with a right or bilateral AC lesion improved their DP mainly by recognizing the pitch at the beginning of the stimuli. The lesioning of the AC in trained animals caused a significant decrease in DP, down to chance levels. Retraining resulted in a significant increase in DP in rats with a left AC lesion; animals with a right lesion improved only slightly. The results demonstrate a hemispheric asymmetry of the rat AC in the recognition of FM stimuli and indicate the dominance of the right AC in the discrimination of the direction of frequency modulation. [source]

    SK channels and the varieties of slow after-hyperpolarizations in neurons

    Fivos Vogalis
    Abstract Action potentials and associated Ca2+ influx can be followed by slow after-hyperpolarizations (sAHPs) caused by a voltage-insensitive, Ca2+ -dependent K+ current. Slow AHPs are a widespread phenomenon in mammalian (including human) neurons and are present in both peripheral and central nervous systems. Although, the molecular identity of ion channels responsible for common membrane potential mechanisms has been largely determined, the nature of the channels that underlie the sAHPs in neurons, both in the brain and in the periphery, remains unresolved. This short review discusses why there is no clear molecular candidate for sAHPs. [source]

    Between Immigration and Policing: Cross Recognition

    EUROPEAN LAW JOURNAL, Issue 2 2004
    Andrew Nicol
    The Dublin Convention of 1990 addressed some of the problems which this policy created, but left others unresolved. Domestic legislation has progressively reduced the opportunities for challenging safe third-country removals, especially to an EU state. The incorporation of the European Convention on Human Rights into UK law has generated new possibilities for challenging safe third-country decisions where removal might damage physical or mental health. Articles 3 and 8 have been invoked in particular. The Dublin machinery established ,rules' to decide which member state was responsible for considering the asylum claim and the procedure to be followed. The article examines why the UK courts have said that these provisions are not justiciable in the English courts. Finally the article considers whether the experience with Dublin provides any useful guidance as to the approach that will be taken to European arrest warrants and extradition requests. [source]


    EVOLUTION, Issue 7 2007
    Mickael Le Gac
    Despite important advances in the last few years, the evolution of reproductive isolation (RI) remains an unresolved and critical gap in our understanding of speciation processes. In this study, we investigated the evolution of RI among species of the parasitic fungal species complex Microbotryum violaceum, which is responsible for anther smut disease of the Caryophyllaceae. We found no evidence for significant positive assortative mating by M. violaceum even over substantial degrees of genetic divergence, suggesting a lack of prezygotic isolation. In contrast, postzygotic isolation increased with the genetic distance between mating partners when measured as hyphal growth. Total RI, measured as the ability of the pathogen to infect and produce a diploid progeny in the host plant, was significantly and positively correlated with genetic distance, remaining below complete isolation for most of the species pairs. The results of this study, the first one on the time course of speciation in a fungus, are therefore consistent with previous works showing that RI generally evolves gradually with genetic distance, and thus presumably with time. Interestingly, prezygotic RI due to gamete recognition did not increase with genetic distance, in contrast to the pattern found in plants and animals. [source]


    EVOLUTION, Issue 11 2006
    Reinhard Bürger
    Abstract It has been shown theoretically that sympatric speciation can occur if intraspecific competition is strong enough to induce disruptive selection. However, the plausibility of the involved processes is under debate, and many questions on the conditions for speciation remain unresolved. For instance, is strong disruptive selection sufficient for speciation? Which roles do genetic architecture and initial composition of the population play? How strong must assortative mating be before a population can split in two? These are some of the issues we address here. We investigate a diploid multilocus model of a quantitative trait that is under frequency-dependent selection caused by a balance of intraspecific competition and frequency-independent stabilizing selection. This trait also acts as mating character for assortment. It has been established previously that speciation can occur only if competition is strong enough to induce disruptive selection. We find that speciation becomes more difficult for very strong competition, because then extremely strong assortment is required. Thus, speciation is most likely for intermediate strengths of competition, where it requires strong, but not extremely strong, assortment. For this range of parameters, however, it is not obvious how assortment can evolve from low to high levels, because with moderately strong assortment less genetic variation is maintained than under weak or strong assortment sometimes none at all. In addition to the strength of frequency-dependent competition and assortative mating, the roles of the number of loci, the distribution of allelic effects, the initial conditions, costs to being choosy, the strength of stabilizing selection, and the particular choice of the fitness function are explored. A multitude of possible evolutionary outcomes is observed, including loss of all genetic variation, splitting in two to five species, as well as very short and extremely long stable limit cycles. On the methodological side, we propose quantitative measures for deciding whether a given distribution reflects two (or more) reproductively isolated clusters. [source]

    Leukocyte extravasation as a target for anti-inflammatory therapy , Which molecule to choose?

    W.-H. Boehncke
    Despite some disappointments during the clinical use of these agents and despite their crippling price tag, the recent incorporation of biologicals that target defined molecular controls of leukocyte extravasation into dermatological and rheumatological practise, consequently, has greatly enriched our therapeutic options for battling major, chronic, inflammatory dermatoses such as psoriasis. However, the , as yet unresolved and still rather controversially discussed , critical question is: Which of the multiple steps that control leukocyte extravasation in the human system really offer the most promising, most pragmatic, and safest molecular targets for therapeutic intervention for which disease entity? The current debate intends to stimulate public and rational debate of this crucial issue, beyond the evident commercial interests that are touched by whatever stand one takes. [source]

    Defining Factors of Successful University-Community Collaborations: An Exploration of One Healthy Marriage Project

    FAMILY RELATIONS, Issue 1 2009
    Erik L. Carlton
    This study explored university-community collaborations by examining the workings of 1 healthy marriage initiative. An ethnographic case study research strategy was used to study the process of this initiative, specifically looking at how participants worked through and overcame traditional university-community collaboration challenges. Data consist of qualitative interviews with key initiative collaborators. Findings are organized into a model that offers a new way of looking at university-community collaborations in light of challenge points to be addressed and either resolved or unresolved. The model provides implications for other collaborative efforts and outreach scholarship. [source]

    Proteome analysis of human nuclear insoluble fractions

    GENES TO CELLS, Issue 8 2009
    Hideaki Takata
    The interphase nucleus is a highly ordered and compartmentalized organelle. Little is known regarding what elaborate mechanisms might exist to explain these properties of the nucleus. Also unresolved is whether some architectural components might facilitate the formation of functional intranuclear compartments or higher order chromatin structure. As the first step to address these questions, we performed an in-depth proteome analysis of nuclear insoluble fractions of human HeLa-S3 cells prepared by two different approaches: a high-salt/detergent/nuclease-resistant fraction and a lithium 3,5-diiodosalicylate/nuclease-resistant fraction. Proteins of the fractions were analyzed by liquid chromatography electrospray ionization tandem mass spectrometry, identifying 333 and 330 proteins from each fraction respectively. Among the insoluble nuclear proteins, we identified 37 hitherto unknown or functionally uncharacterized proteins. The RNA recognition motif, WD40 repeats, HEAT repeats and the SAP domain were often found in these identified proteins. The subcellular distribution of selected proteins, including DEK protein and SON protein, demonstrated their novel associations with nuclear insoluble materials, corroborating our MS-based analysis. This study establishes a comprehensive catalog of the nuclear insoluble proteins in human cells. Further functional analysis of the proteins identified in our study will significantly improve our understanding of the dynamic organization of the interphase nucleus. [source]

    Thrombopoietin-induced CXC chemokines, NAP-2 and PF4, suppress polyploidization and proplatelet formation during megakaryocyte maturation

    GENES TO CELLS, Issue 1 2003
    Masaaki Oda
    Background:, We previously reported that the expressions of two CXC chemokines, neutrophil activating peptide-2 (NAP-2) and platelet factor-4 (PF-4), were induced by megakaryocyte-specific cytokine thrombopoietin (TPO) in mouse bone marrow megakaryocytes. The roles of these chemokines on megakaryocyte maturation/differentiation processes, including polyploidization and proplatelet formation (PPF) remain unresolved. Results: ,NAP-2 and PF-4 suppressed the PPF of mature megakaryocytes freshly prepared from mouse bone marrow as well as that of the megakaryocyte progenitors, c-Kit+CD41+ cells, isolated from mouse bone marrow and cultured with TPO. NAP-2 and PF-4 inhibited polyploidization of c-Kit+CD41+ cells in the presence of TPO, and also inhibited the proliferation of c-Kit+CD41+ cells. Conclusions: ,NAP-2 and PF-4 produced by TPO stimulation in megakaryocytes suppress megakaryocyte maturation and proliferation as a feedback control. [source]

    Translocation,excision,deletion,amplification mechanism leading to nonsyntenic coamplification of MYC and ATBF1,

    Nadine Van Roy
    Despite oncogene amplification being a characteristic of many tumor types, the mechanisms leading to amplicon formation have remained largely unresolved. In this study, we used a combinatorial approach of fluorescence in situ hybridization and single-nucleotide polymorphism chip gene copy number analyses to unravel the mechanism leading to nonsyntenic coamplification of MYC and ATBF1 in SJNB-12 cells. To explain our findings, we propose a complex series of events consisting of multiple double-strand breaks, accompanied (or triggered) by the formation of a reciprocal translocation t(8;16), as well as excisions and deletions near the translocation breakpoints. This study provides evidence for a translocation,excision,deletion,amplification sequence of events rather than a breakage,fusion,bridge model, which has been more frequently proposed to explain proto-oncogene amplification. Furthermore, it illustrates the power of presently available tools for detailed analysis of the complex rearrangements that accompany amplicon formation. © 2005 Wiley-Liss, Inc. [source]

    Using DC resistivity tomography to detect and characterize mountain permafrost

    Christian Hauck
    ABSTRACT Direct-current (DC) resistivity tomography has been applied to different mountain permafrost regions. Despite problems with the very high resistivities of the frozen material, plausible results were obtained. Inversions with synthetic data revealed that an appropriate choice of regularization constraints was important, and that a joint analysis of several tomograms computed with different constraints was required to judge the reliability of individual features. The theoretical results were verified with three field experiments conducted in the Swiss and the Italian Alps. At the first site, near Zermatt, Switzerland, the location and the approximate lateral and vertical extent of an ice core within a moraine could be delineated. On the Murtel rock glacier, eastern Swiss Alps, a steeply dipping boundary at its frontal part was observed, and extremely high resistivities of several M, indicated a high ice content. The base of the rock glacier remained unresolved by the DC resistivity measurements, but it could be constrained with transient EM soundings. On another rock glacier near the Stelvio Pass, eastern Italian Alps, DC resistivity tomography allowed delineation of the rock glacier base, and the only moderately high resistivities within the rock glacier body indicated that the ice content must be lower compared with the Murtel rock glacier. [source]

    Pharmacological interventions in aging and age-associated disorders

    Kenichi Kitani
    In the present study, past attempts using different pharmaceuticals and chemicals which were reported to prolong lifespans of animals are critically reviewed. Despite a large number of trials in animals and humans, the validity of supplementation of antioxidant vitamins such as vitamins A, E and C for improving human health remains unresolved at present. A recent approach using antioxidant mimetics called the EUK series which, despite an initial enthusiastically reported success in prolonging the lifespan of nematodes, remains again unsettled because of the failure in reproducing the initial success by follow-up studies. ,-Phenyl- tert -butylnitrone and related nitrones were initially introduced as radical scavengers. Some of these (e.g. disodium 2,4-disulfophenyl-N- tert -butylnitrone) are at phase 3 clinical trials as an agent to treat cerebral stroke. This effect, however, appears at least in part to be related to signal transduction which makes these agents effective against cerebral stroke even when they are administered later than its onset. (,)Deprenyl is a monoamine oxidase-B inhibitor and has some neuroprotective and anti-apoptotic effects. The drug has also been shown to prolong the lifespans of at least four different animal species. The drug upregulates superoxide dismutase and catalase activities in selective brain regions of dopaminergic nature. These effects on antioxidant enzyme activities are suspected to be causally related to its effect on lifespans of animals. Future trials using these and other drugs are expected to open new doors for interventions in aging and age-associated disorders in humans. [source]

    Stocks and dynamics of SOC in relation to soil redistribution by water and tillage erosion

    GLOBAL CHANGE BIOLOGY, Issue 10 2006
    Abstract Soil organic carbon (SOC) displaced by soil erosion is the subject of much current research and the fundamental question, whether accelerated soil erosion is a source or sink of atmospheric CO2, remains unresolved. A toposequence of terraced fields as well as a long slope was selected from hilly areas of the Sichuan Basin, China to determine effects of soil redistribution rates and processes on SOC stocks and dynamics. Soil samples for the determination of caesium-137 (137Cs), SOC, total N and soil particle size fractions were collected at 5 m intervals along a transect down the two toposequences. 137Cs data showed that along the long slope transect soil erosion occurred in upper and middle slope positions and soil deposition appeared in the lower part of the slope. Along the terraced transect, soil was lost over the upper parts of the slopes and deposition occurred towards the downslope boundary on each terrace, resulting in very abrupt changes in soil redistribution over short distances either side of terrace boundaries that run parallel with the contour on the steep slopes. These data reflect a difference in erosion process; along the long slope transect, water erosion is the dominant process, while in the terraced landscape soil distribution is mainly the result of tillage erosion. SOC inventories (mass per unit area) show a similar pattern to the 137Cs inventory, with relatively low SOC content in the erosional sites and high SOC content in depositional areas. However, in the terraced field landscape C/N ratios were highest in the depositional areas, while along the long slope transect, C/N ratios were highest in the erosional areas. When the samples are subdivided based on 137Cs-derived erosion and deposition data, it is found that the erosional areas have similar C/N ratios for both toposequences, while the C/N ratios in depositional areas are significantly different from each other. These differences are attributed to the difference in soil erosion processes; tillage erosion is mainly responsible for high-SOC inventories at depositional positions on terraced fields, whereas water erosion plays a primary role in SOC storage at depositional positions on the long slope. These data support the theory that water erosion may cause a loss of SOC due to selective removal of the most labile fraction of SOC, while on the other hand tillage erosion only transports the soil over short distances with less effect on the total SOC stock. [source]

    Surprises from the crystal structure of the hepatitis C virus NS2-3 protease,

    HEPATOLOGY, Issue 6 2006
    Jerome Gouttenoire Ph.D.
    Hepatitis C virus is a major global health problem affecting an estimated 170 million people worldwide. Chronic infection is common and can lead to cirrhosis and liver cancer. There is no vaccine available and current therapies have met with limited success. The viral RNA genome encodes a polyprotein that includes 2 proteases essential for virus replication. The NS2-3 protease mediates a single cleavage at the NS2/NS3 junction, whereas the NS3-4A protease cleaves at 4 downstream sites in the polyprotein. NS3-4A is characterized as a serine protease with a chymotrypsin-like fold, but the enzymatic mechanism of the NS2-3 protease remains unresolved. Here, we report the crystal structure of the catalytic domain of the NS2-3 protease at 2.3 Å resolution. The structure reveals a dimeric cysteine protease with 2 composite active sites. For each active site, the catalytic histidine and glutamate residues are contributed by one monomer, and the nucleophilic cysteine by the other. The carboxy-terminal residues remain coordinated in the 2 active sites, predicting an inactive postcleavage form. Proteolysis through formation of a composite active site occurs in the context of the viral polyprotein expressed in mammalian cells. These features offer unexpected insights into polyprotein processing by hepatitis C virus and new opportunities for antiviral drug design. [source]

    New Historicism: Postmodern Historiography Between Narrativism and Heterology

    HISTORY AND THEORY, Issue 1 2000
    Jürgen Pieters
    In recent discussionsof the work of new historicist critics like Stephen Greenblatt and Louis Montrose, it has oftenbeen remarked that the theory of history underlying their reading practice closely resembles thatof postmodern historiographers like Hayden White and Frank Ankersmit. Taking off from onesuch remark, the aim of the present article is twofold. First, I intend to provide a theoretical basisfrom which to substantiate the idea that new historicism can indeed be taken to be the literary-critical variant of what Frank Ankersmit has termed the "new historiography." Inthe second half of the article, this theoretical foundation will serve as the starting point of afurther analysis of both the theory and practice of new historicism in terms of its distinctlypostmodern historiographical project. I will argue that in order to fully characterize the newhistoricist reading method, we do well to distinguish between two variants of postmodernhistoricism: a narrativist one (best represented in the work of Michel Foucault) and aheterological one (of which Michel de Certeau's writings serve as a supreme example). Abrief survey of the two methodological options associated with these variants (discursive versuspsychoanalytical) is followed by an analysis of the work of the central representative of newhistoricism, Stephen Greenblatt. While the significant use of historical anecdotes in his workleaves unresolved the question to which of either approaches Greenblatt belongs, the distinctiondoes serve a clear heuristic purpose. In both cases, it points to the dangerous spot where the newhistoricism threatens to fall prey to the evils of the traditional historicism against which it defineditself. [source]

    Maternal resolution of loss and abuse: Associations with adjustment to the transition to parenthood

    Kim Leon
    This study examined relationships between mothers' resolution of past loss and abuse and their adjustment to the transition to parenthood. Three groups of mothers were compared: 1) those who were unresolved with respect to loss or abuse (Unresolved Loss/Abuse), 2) those who had experienced loss or abuse, but were considered resolved (Resolved Loss/Abuse), and 3) those who had not experienced loss or abuse (No Loss/Abuse). Mothers in the Resolved Loss/Abuse group reported more negative perceptions of the transition to parenthood than did mothers in the No Loss/Abuse group, which may reflect a greater awareness of negative emotions and a greater ability to communicate openly about them. Although mothers who have experienced loss or abuse and appear to have resolved these experiences may be at risk for distress during the transition to parenthood, they do not appear to be at risk for insensitive care giving. Unresolved loss, however, was associated with less sensitive care giving. The findings of this study highlight the importance of examining current state of mind regarding past experiences when investigating relationships between childhood loss and abuse and adjustment to subsequent life transitions. ©2004 Michigan Association for Infant Mental Health. [source]

    High incidence of rheumatic fever and Rheumatic heart disease in the republics of Central Asia

    Nazgul A. OMURZAKOVA
    Abstract The epidemiological situation involving rheumatic fever (RF) and rheumatic heart disease (RHD) not only remains unresolved but is also a cause of serious concern due to the rapid increase in the incidence of RF/RHD in many developing countries. After the collapse of the Soviet Union, the republics of Central Asia experienced an economic decline that directly affected the public health sector of this region. This is the main cause of the high prevalence of many infectious diseases in Central Asia, including streptococcal tonsillopharyngitis, which carries the risk of complications such as RF. The difficulty involved in early diagnosis of RF and the development of RHD among children and adolescents causes early mortality and sudden death, leading to economic damage in these countries due to the loss of the young working population. Among all the developing countries, Kyrgyzstan, which is located in the heart of Central Asia, has the highest prevalence of RF/RHD. The increase in the prevalence of RF in Central Asia can be attributed to factors such as the low standard of living and changes in the virulence of streptococci and their sensitivity to antibiotics. [source]

    Global output feedback stabilization of upper-triangular nonlinear systems using a homogeneous domination approach

    Chunjiang Qian
    Abstract This paper addresses the problem of global output feedback stabilization for a class of upper-triangular systems with perturbing nonlinearities that are higher-order in the unmeasurable states. A new design method based on the homogeneous domination approach and finite-time stabilization technique is developed, which leads to global output feedback stabilizers for the upper-triangular nonlinear systems under a homogeneous growth condition. A new perspective shown in this paper is that the finite-time stabilization, in addition to its faster convergence rate, can also be utilized to handle control problems that were previously unresolved under asymptotic stabilization. Copyright © 2006 John Wiley & Sons, Ltd. [source]