1,511 research outputs found
Evolutionary history and identification of conservation units in the giant otter, Pteronura brasiliensis.
The giant otter, Pteronura brasiliensis, occupies a range including the major drainage basins of South America, yet the degree of structure that exists within and among populations inhabiting these drainages is unknown. We sequenced portions of the mitochondrial DNA (mtDNA) cytochrome b (612 bp) and control region (383 bp) genes in order to determine patterns of genetic variation within the species. We found high levels of mtDNA haplotype diversity (h = 0.93 overall) and support for subdivision into four distinct groups of populations, representing important centers of genetic diversity and useful units for prioritizing conservation within the giant otter. We tested these results against the predictions of three hypotheses of Amazonian diversification (Pleistocene Refugia, Paleogeography, and Hydrogeology). While the phylogeographic pattern conformed to the predictions of the Refugia Hypothesis, molecular dating using a relaxed clock revealed the phylogroups diverged from one another between 1.69 and 0.84 Ma, ruling out the influence of Late Pleistocene glacial refugia. However, the role of Plio-Pleistocene climate change could not be rejected. While the molecular dating also makes the influence of geological arches according to the Paleogeography Hypothesis extremely unlikely, the recent Pliocene formation of the Fitzcarrald Arch and its effect of subsequently altering drainage pattern could not be rejected. The data presented here support the interactions of both climatic and hydrological changes resulting from geological activity in the Plio-Pleistocene, in shaping the phylogeographic structure of the giant otter
A phase 3 multicenter, prospective, open-label efficacy and safety study of immune globulin (human) 10% caprylate/chromatography purified in patients with myasthenia gravis exacerbations
Background: Myasthenia gravis (MG) is an autoimmune disorder affecting neuromuscular transmission. Exacerbations may involve increasing bulbar weakness and/or sudden respiratory failure, both of which can be critically disabling. Management of MG exacerbations includes plasma exchange and intravenous immunoglobulin (IVIG); they are equally effective, but patients experience fewer side effects with IVIG. The objective of this study was to assess the efficacy and safety of immune globulin caprylate/chromatography purified (IGIV-C) in subjects with MG exacerbations. Methods: This prospective, open-label, non-controlled 28-day clinical trial was conducted in adults with MG Foundation of America class IVb or V status. Subjects received IGIV-C 2 g/kg over 2 consecutive days (1 g/kg/day) and were assessed for efficacy/safety on Days 7, 14, 21, and 28. The primary efficacy endpoint was the change from Baseline in quantitative MG (QMG) score to Day 14. Secondary endpoints of clinical response, Baseline to Day 14, included at least a 3-point decrease in QMG and MG Composite and a 2-point decrease in MG-activities of daily living (MG-ADL). Results: Forty-nine subjects enrolled. The change in QMG score at Day 14 was significant (p < 0.001) in the Evaluable (-6.4, n = 43) and Safety (-6.7, n = 49) populations. Among evaluable subjects, Day 14 response rates were 77, 86, and 88% for QMG, MG Composite, and MG-ADL, respectively. IGIV-C showed good tolerability with no serious adverse events. Conclusions: The results of this study show that IGIV-C was effective, safe, and well tolerated in the treatment of MG exacerbations
Distraction from pain and executive functioning: an experimental investigation of the role of inhibition, task switching and working memory
Although many studies have investigated the effectiveness of distraction as a method of pain control, the cognitive processes by which attentional re-direction is achieved, remain unclear. In this study the role of executive functioning abilities (inhibition, task switching and working memory) in the effectiveness of distraction is investigated. We hypothesized that the effectiveness of distraction in terms of pain reduction would be larger in participants with better executive functioning abilities. Ninety-one undergraduate students first performed executive functioning tasks, and subsequently participated in a cold pressor task (CPT). Participants were randomly assigned to (1) a distraction group, in which an attention-demanding tone-detection task was performed during the CPT, or (2) a control group, in which no distraction task was performed. Participants in the distraction group reported significantly less pain during the CPT, but the pain experience was not influenced by executive functioning abilities. However, the performance on the distraction task improved with better inhibition abilities, indicating that inhibition abilities might be important in focussing on a task despite the pain
The Subeng mammal site (Late Paleocene, China): evidence for a unique woodland on the dry Mongolian Plateau
The COOH-Terminal Peptide of Platelet Factor-4 Variant (CXCL4L1/PF-4var47-70) Strongly Inhibits Angiogenesis and Suppresses B16 Melanoma Growth In vivo.
Chemokines influence tumor growth directly or indirectly via both angiogenesis and tumor-leukocyte interactions. Platelet factor-4 (CXCL4/PF-4), which is released from alpha-granules of activated platelets, is the first described angiostatic chemokine. Recently, it was found that the variant of CXCL4/PF-4 (CXCL4L1/PF-4var) could exert a more pronounced angiostatic and antitumoral effect than CXCL4/PF-4. However, the molecular mechanisms of the angiostatic activities of the PF-4 forms remain partially elusive. Here, we studied the biological properties of the chemically synthesized COOH-terminal peptides of CXCL4/PF-4 (CXCL4/PF-4(47-70)) and CXCL4L1/PF-4var (CXCL4L1/PF-4var(47-70)). Both PF-4 peptides lacked monocyte and lymphocyte chemotactic activity but equally well inhibited (25 nmol/L) endothelial cell motility and proliferation in the presence of a single stimulus (i.e., exogenous recombinant fibroblast growth factor-2). In contrast, when assayed in more complex angiogenesis test systems characterized by the presence of multiple mediators, including in vitro wound-healing (2.5 nmol/L versus 12.5 nmol/L), Matrigel (60 nmol/L versus 300 nmol/L), and chorioallantoic membrane assays, CXCL4L1/PF-4var(47-70) was found to be significantly (5-fold) more angiostatic than CXCL4/PF-4(47-70). In addition, low (7 mug total) doses of intratumoral CXCL4L1/PF-4var(47-70) inhibited B16 melanoma growth in mice more extensively than CXCL4/PF-4(47-70). This antitumoral activity was predominantly mediated through inhibition of angiogenesis (without affecting blood vessel stability) and induction of apoptosis, as evidenced by immunohistochemical and fluorescent staining of B16 tumor tissue. In conclusion, CXCL4L1/PF-4var(47-70) is a potent antitumoral and antiangiogenic peptide. These results may represent the basis for the design of CXCL4L1/PF-4var COOH-terminal-derived peptidomimetic anticancer drugs. Mol Cancer Res; 8(3); 322-34
Tree genetic resources at risk in South America: A spatial threat assessment to prioritize populations for conservation
Background
Humans threat the populations of tree species by overexploitation, deforestation, land use change, and climate change. We present a novel threat assessment at intraspecific level to support the conservation of genetic resources of 80 socioeconomically viable tree species in South America. In this assessment, we evaluate the threat status of Ecogeographic Range Segments (ERSs). ERSs are groups of populations of a specific species in a certain ecological zone of a particular grid cell of a species’ geographic occupancy.
Methods
We used species location records to determine the species distributions and species‐specific ERSs. We distinguished eight threat situations to assess the risk of extirpation of the ERSs of all 80 species. These threat situations were determined by large or little tree cover, low or high human pressure, and low or high climate change impact. Available layers of tree cover and threats were used to determine the levels of fragmentation and direct human pressure. Maxent niche modelling with two Global Circulation Models helped determining climate change impact by the 2050s.
Results
When all 80 species are considered, in total, 59% of the ERSs are threatened by little tree cover or high human pressure. When climate change is also considered, then 71‐73% of the ERSs are threatened. When an increased risk of extirpation of populations outside protected areas is considered, then 84–86% of the ERSs are threatened. Seven species warrant special attention because all their ERSs are threatened across their whole distribution in South America: Balfourondendron riedelianum, Cariniana legalis, Dalbergia nigra, Handroanthus pulcherrimus, Pachira quintana, Prosopis flexuosa, and Prosopis pallida.
Conclusions
Our results confirm the urgency to set up a regional action plan for the conservation of tree genetic resources in South America. With this threat assessment, we aim to support governments and organizations who are taking up this task
Erasmus Language students in a British University – a case study
Students’ assessment of their academic experience is actively sought by Higher Education institutions, as evidenced in the National Student Survey introduced in 2005. Erasmus students, despite their growing numbers, tend to be excluded from these satisfaction surveys, even though they, too, are primary customers of a University. This study aims to present results from bespoke questionnaires and semi-structured interviews with a sample of Erasmus students studying languages in a British University. These methods allow us insight into the experience of these students and their assessment as a primary customer, with a focus on language learning and teaching, university facilities and student support. It investigates to what extent these factors influence their levels of satisfaction and what costs of adaptation if any, they encounter. Although excellent levels of satisfaction were found, some costs affect their experience. They relate to difficulties in adapting to a learning methodology based on a low number of hours and independent learning and to a guidance and support system seen as too stifling. The results portray this cohort’s British University as a well-equipped and well-meaning but ultimately overbearing institution, which may indicate that minimising costs can eliminate some sources of dissatisfaction
Increased chromosomal radiosensitivity in asymptomatic carriers of a heterozygous BRCA1 mutation
Background: Breast cancer risk increases drastically in individuals carrying a germline BRCA1 mutation. The exposure to ionizing radiation for diagnostic or therapeutic purposes of BRCA1 mutation carriers is counterintuitive, since BRCA1 is active in the DNA damage response pathway. The aim of this study was to investigate whether healthy BRCA1 mutations carriers demonstrate an increased radiosensitivity compared with healthy individuals.
Methods: We defined a novel radiosensitivity indicator (RIND) based on two endpoints measured by the G2 micronucleus assay, reflecting defects in DNA repair and G2 arrest capacity after exposure to doses of 2 or 4 Gy. We investigated if a correlation between the RIND score and nonsense-mediated decay (NMD) could be established.
Results: We found significantly increased radiosensitivity in the cohort of healthy BRCA1 mutation carriers compared with healthy controls. In addition, our analysis showed a significantly different distribution over the RIND scores (p = 0.034, Fisher’s exact test) for healthy BRCA1 mutation carriers compared with non-carriers: 72 % of mutation carriers showed a radiosensitive phenotype (RIND score 1–4), whereas 72 % of the healthy volunteers showed no radiosensitivity (RIND score 0). Furthermore, 28 % of BRCA1 mutation carriers had a RIND score of 3 or 4 (not observed in control subjects). The radiosensitive phenotype was similar for relatives within several families, but not for unrelated individuals carrying the same mutation. The median RIND score was higher in patients with a mutation leading to a premature termination codon (PTC) located in the central part of the gene than in patients with a germline mutation in the 5′ end of the gene.
Conclusions: We show that BRCA1 mutations are associated with a radiosensitive phenotype related to a compromised DNA repair and G2 arrest capacity after exposure to either 2 or 4 Gy. Our study confirms that haploinsufficiency is the mechanism involved in radiosensitivity in patients with a PTC allele, but it suggests that further research is needed to evaluate alternative mechanisms for mutations not subjected to NMD
Comparing the hierarchy of keywords in on-line news portals
The tagging of on-line content with informative keywords is a widespread
phenomenon from scientific article repositories through blogs to on-line news
portals. In most of the cases, the tags on a given item are free words chosen
by the authors independently. Therefore, relations among keywords in a
collection of news items is unknown. However, in most cases the topics and
concepts described by these keywords are forming a latent hierarchy, with the
more general topics and categories at the top, and more specialised ones at the
bottom. Here we apply a recent, cooccurrence-based tag hierarchy extraction
method to sets of keywords obtained from four different on-line news portals.
The resulting hierarchies show substantial differences not just in the topics
rendered as important (being at the top of the hierarchy) or of less interest
(categorised low in the hierarchy), but also in the underlying network
structure. This reveals discrepancies between the plausible keyword association
frameworks in the studied news portals
Water dispersible microbicidal cellulose acetate phthalate film
BACKGROUND: Cellulose acetate phthalate (CAP) has been used for several decades in the pharmaceutical industry for enteric film coating of oral tablets and capsules. Micronized CAP, available commercially as "Aquateric" and containing additional ingredients required for micronization, used for tablet coating from water dispersions, was shown to adsorb and inactivate the human immunodeficiency virus (HIV-1), herpesviruses (HSV) and other sexually transmitted disease (STD) pathogens. Earlier studies indicate that a gel formulation of micronized CAP has a potential as a topical microbicide for prevention of STDs including the acquired immunodeficiency syndrome (AIDS). The objective of endeavors described here was to develop a water dispersible CAP film amenable to inexpensive industrial mass production. METHODS: CAP and hydroxypropyl cellulose (HPC) were dissolved in different organic solvent mixtures, poured into dishes, and the solvents evaporated. Graded quantities of a resulting selected film were mixed for 5 min at 37°C with HIV-1, HSV and other STD pathogens, respectively. Residual infectivity of the treated viruses and bacteria was determined. RESULTS: The prerequisites for producing CAP films which are soft, flexible and dispersible in water, resulting in smooth gels, are combining CAP with HPC (other cellulose derivatives are unsuitable), and casting from organic solvent mixtures containing ≈50 to ≈65% ethanol (EtOH). The films are ≈100 µ thick and have a textured surface with alternating protrusions and depressions revealed by scanning electron microscopy. The films, before complete conversion into a gel, rapidly inactivated HIV-1 and HSV and reduced the infectivity of non-viral STD pathogens >1,000-fold. CONCLUSIONS: Soft pliable CAP-HPC composite films can be generated by casting from organic solvent mixtures containing EtOH. The films rapidly reduce the infectivity of several STD pathogens, including HIV-1. They are converted into gels and thus do not have to be removed following application and use. In addition to their potential as topical microbicides, the films have promise for mucosal delivery of pharmaceuticals other than CAP
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