102 research outputs found
External tagging does not affect the feeding behavior of a coral reef fish, Chaetodon vagabundus (Pisces: Chaetodontidae)
Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of for personal use, not for redistribution. The definitive version was published in Environmental Biology of Fishes 86 (2009): 447-450, doi:10.1007/s10641-009-9545-9.Increasingly, the ability to recognize individual fishes is important for studies of population
dynamics, ecology, and behavior. Although a variety of methods exist, external tags remain one
of the most widely applied because they are both effective and cost efficient. However, a key
assumption is that neither the tagging procedure nor the presence of a tag negatively affects the
individual. While this has been demonstrated for relatively coarse metrics such as growth and
survival, few studies have examined the impact of tags and tagging on more subtle aspects of
behavior. We tagged adult vagabond butterflyfish (Chaetodon vagabundus) occupying a 30-ha
insular reef in Kimbe Bay, Papua New Guinea, using a commonly-utilized t-bar anchor tag. We
quantified and compared feeding behavior (bite rate), which is sensitive to stress, of tagged and
untagged individuals over four separate sampling periods spanning four months post-tagging.
Bite rates did not differ between tagged and untagged individuals at each sampling period and,
combined with additional anecdotal observations of normal pairing behavior and successful
reproduction, suggest that tagging did not adversely affect individuals.The authors gratefully
acknowledge funding from the Fulbright Program, National Science Foundation and the
Australian Research Council
Demographic and Clinical Features of Dengue Fever in Pakistan from 2003–2007: A Retrospective Cross-Sectional Study
Background: Demographic features of dengue fever have changed tremendously in Pakistan over the past two decades. Small scale studies from all over the country have reported different aspects of individual outbreaks during this time. However, there is scarcity of data looking at the overall trend of dengue virus infection in the country. In this study, we examined annual trends, seasonality, and clinical features of dengue fever in the Pakistani population.Methods: Demographic information and dengue IgM status of all patients tested for dengue IgM antibody at Aga Khan University Hospital from January 2003 to December 2007 were analyzed to look for trends of IgM-positive cases in Pakistan. In addition, clinical and biochemical parameters were abstracted retrospectively from medical records of all patients hospitalized with IgM-proven dengue fever between January 2006 and December 2007. These patients were categorized into dengue fever and dengue hemorrhagic fever according to the WHO severity grading scale.Results: Out of a total of 15040 patients (63.2% male and 36.8% female), 3952 (26.3%) tested positive for dengue IgM antibody. 209 IgM proven dengue patients were hospitalized during the study period. During 2003, IgM positive cases were seen only during the months of July-December. In contrast, such cases were detected throughout the year from the 2004– 2007. The median age of IgM positive patients decreased every year from 32.0 years in 2003 to 24.0 years in 2007 (p,0.001). Among hospitalized patients, nausea was the most common presenting feature found in 124/209 (59.3%) patients. Children presented with a higher median body temperature than adults (p = 0.010). In addition, neutropenia was seen more commonly in children while raised serum ALT levels were seen more commonly in adults (both p = 0.006). While a low total white cell count was more common in patients with dengue fever as compared to Dengue Hemorrhagic Fever (p = 0.020), neutropenia (p = 0.019), monocytosis (p = 0.001) and raised serum ALT level (p = 0.005) were observed more commonly in the latter group.Conclusions: Dengue virus is now endemic in Pakistan, circulating throughout the year with a peak incidence in the post monsoon period. Median age of dengue patients has decreased and younger patients may be more susceptible. Total and differential leukocyte counts may help identify patients at risk of hemorrhage
In vitro susceptibility to pyrimethamine of DHFR I164L single mutant Plasmodium falciparum
<p>Abstract</p> <p>Background</p> <p>Recently, <it>Plasmodium falciparum </it>parasites bearing <it>Pfdhfr </it>I164L single mutation were found in Madagascar. These new mutants may challenge the use of antifolates for the intermittent preventive treatment of malaria during pregnancy (IPTp). Assays with transgenic bacteria suggested that I164L parasites have a wild-type phenotype for pyrimethamine but it had to be confirmed by testing the parasites themselves.</p> <p>Methods</p> <p>Thirty <it>Plasmodium falciparum </it>clinical isolates were collected in 2008 in the south-east of Madagascar. A part of <it>Pfdhfr </it>gene encompassing codons 6 to 206 was amplified by PCR and the determination of the presence of single nucleotide polymorphisms was performed by DNA sequencing. The multiplicity of infection was estimated by using an allelic family-specific nested PCR. Isolates that appeared monoclonal were submitted to culture adaptation. Determination of IC<sub>50s </sub>to pyrimethamine was performed on adapted isolates.</p> <p>Results</p> <p>Four different <it>Pfdhfr </it>alleles were found: the 164L single mutant-type (N = 13), the wild-type (N = 7), the triple mutant-type 51I/59R/108N (N = 9) and the double mutant-type 108N/164L (N = 1). Eleven out 30 (36.7%) of <it>P. falciparum </it>isolates were considered as monoclonal infection. Among them, five isolates were successfully adapted in culture and tested for pyrimethamine <it>in vitro </it>susceptibility. The wild-type allele was the most susceptible with a 50% inhibitory concentration (IC<sub>50</sub>) < 10 nM. The geometric mean of IC<sub>50 </sub>of the three I164L mutant isolates was 6-fold higher than the wild-type with 61.3 nM (SD = 3.2 nM, CI95%: 53.9-69.7 nM). These values remained largely below the IC<sub>50 </sub>of the triple mutant parasite (13,804 nM).</p> <p>Conclusion</p> <p>The IC<sub>50</sub>s of the I164L mutant isolates were significantly higher than those of the wild-type (6-fold higher) and close from those usually reported for simple mutants S108N (roughly10-fold higher than wild type). Given the observed values, the determination of IC<sub>50</sub>s directly on parasites did not confirm what has been found on transgenic bacteria. The prevalence increase of the <it>Pfdhfr </it>I164L single mutant parasite since 2006 could be explained by the selective advantage of this allele under sulphadoxine-pyrimethamine pressure. The emergence of highly resistant alleles should be considered in the future, in particular because an unexpected double mutant-type allele S108N/I164L has been already detected.</p
Business angel exits: A theory of planned behaviour perspective
Although there are a handful of studies on business angel investment returns, the business angel literature has given little or no attention to exits and the exit strategy. This is surprising given that a primary objective of investing is to achieve a capital gain through some form of liquidity event. Using the theory of planned behaviour (TPB) as an interpretative heuristic, we examine how exits happen: specifically, what are the motivations to seek an exit and to what extent are they planned or opportunistic? Based on multiple case studies in which business angels were invited to tell the story of their most recent exit(s), the evidence suggests that the majority of liquidity events are the outcome of planned behaviour. We propose a typology of angel-backed investment exits as the basis for identifying future directions for research and developing practical advice to angels on effective business practices
The ketimide ligand is not just an inert spectator: heteroallene insertion reactivity of an actinide-ketimide linkage in a thorium carbene amide ketimide complex
The ketimide anion R2C[DOUBLE BOND]N− is an important class of chemically robust ligand that binds strongly to metal ions and is considered ideal for supporting reactive metal fragments due to its inert spectator nature; this contrasts with R2N− amides that exhibit a wide range of reactivities. Here, we report the synthesis and characterization of a rare example of an actinide ketimide complex [Th(BIPMTMS){N(SiMe3)2}(N[DOUBLE BOND]CPh2)] [2, BIPMTMS=C(PPh2NSiMe3)2]. Complex 2 contains Th[DOUBLE BOND]Ccarbene, Th[BOND]Namide and Th[BOND]Nketimide linkages, thereby presenting the opportunity to probe the preferential reactivity of these linkages. Importantly, reactivity studies of 2 with unsaturated substrates shows that insertion reactions occur preferentially at the Th[BOND]Nketimide bond rather than at the Th[DOUBLE BOND]Ccarbene or Th[BOND]Namide bonds. This overturns the established view that metal-ketimide linkages are purely inert spectators
Study of B0(s)→K0Sh+h′− decays with first observation of B0s→K0SK±π∓ and B0s→K0Sπ+π−
A search for charmless three-body decays of B 0 and B0s mesons with a K0S meson in the final state is performed using the pp collision data, corresponding to an integrated luminosity of 1.0 fb−1, collected at a centre-of-mass energy of 7 TeV recorded by the LHCb experiment. Branching fractions of the B0(s)→K0Sh+h′− decay modes (h (′) = π, K), relative to the well measured B0→K0Sπ+π− decay, are obtained. First observation of the decay modes B0s→K0SK±π∓ and B0s→K0Sπ+π− and confirmation of the decay B0→K0SK±π∓ are reported. The following relative branching fraction measurements or limits are obtained B(B0→K0SK±π∓)B(B0→K0Sπ+π−)=0.128±0.017(stat.)±0.009(syst.), B(B0→K0SK+K−)B(B0→K0Sπ+π−)=0.385±0.031(stat.)±0.023(syst.), B(B0s→K0Sπ+π−)B(B0→K0Sπ+π−)=0.29±0.06(stat.)±0.03(syst.)±0.02(fs/fd), B(B0s→K0SK±π∓)B(B0→K0Sπ+π−)=1.48±0.12(stat.)±0.08(syst.)±0.12(fs/fd)B(B0s→K0SK+K−)B(B0→K0Sπ+π−)∈[0.004;0.068]at90%CL
World Antimalarial Resistance Network (WARN) II: In vitro antimalarial drug susceptibility
Intrinsic resistance of Plasmodium falciparum is clearly a major determinant of the clinical failure of antimalarial drugs. However, complex interactions between the host, the parasite and the drug obscure the ability to define parasite drug resistance in vivo. The in vitro antimalarial drug susceptibility assay determines ex-vivo growth of parasite in the presence of serial drug concentrations and, thus, eliminates host effects, such as drug metabolism and immunity. Although the sensitivity of the parasite to various antimalarials provided by such a test provides an important indicator of intrinsic parasite susceptibility, there are fundamental methodological issues that undermine comparison of in vitro susceptibility both between laboratories and within a single laboratory over time. A network of laboratories is proposed that will agree on the basic parameters of the in vitro test and associated measures of quality control. The aim of the network would be to establish baseline values of sensitivity to commonly used antimalarial agents from key regions of the world, and create a global database, linked to clinical, molecular and pharmacology databases, to support active surveillance to monitor temporal trends in parasite susceptibility. Such a network would facilitate the rapid detection of strains with novel antimalarial resistance profiles and investigate suitable alternative treatments with retained efficacy
Comprehensive phenotypic characterization of late gadolinium enhancement predicts sudden cardiac death in coronary artery disease
Background Late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) offers the potential to noninvasively characterize the phenotypic substrate for sudden cardiac death (SCD). Objectives The authors assessed the utility of infarct characterization by CMR, including scar microstructure analysis, to predict SCD in patients with coronary artery disease (CAD). Methods Patients with stable CAD were prospectively recruited into a CMR registry. LGE quantification of core infarction and the peri-infarct zone (PIZ) was performed alongside computational image analysis to extract morphologic and texture scar microstructure features. The primary outcome was SCD or aborted SCD. Results Of 437 patients (mean age: 64 years; mean left ventricular ejection fraction [LVEF]: 47%) followed for a median of 6.3 years, 49 patients (11.2%) experienced the primary outcome. On multivariable analysis, PIZ mass and core infarct mass were independently associated with the primary outcome (per gram: HR: 1.07 [95% CI: 1.02-1.12]; P = 0.002 and HR: 1.03 [95% CI: 1.01-1.05]; P = 0.01, respectively), and the addition of both parameters improved discrimination of the model (Harrell’s C-statistic: 0.64-0.79). PIZ mass, however, did not provide incremental prognostic value over core infarct mass based on Harrell’s C-statistic or risk reclassification analysis. Severely reduced LVEF did not predict the primary endpoint after adjustment for scar mass. On scar microstructure analysis, the number of LGE islands in addition to scar transmurality, radiality, interface area, and entropy were all associated with the primary outcome after adjustment for severely reduced LVEF and New York Heart Association functional class of >1. No scar microstructure feature remained associated with the primary endpoint when PIZ mass and core infarct mass were added to the regression models. Conclusions Comprehensive LGE characterization independently predicted SCD risk beyond conventional predictors used in implantable cardioverter-defibrillator (ICD) insertion guidelines. These results signify the potential for a more personalized approach to determining ICD candidacy in CAD
Self-reported drunkenness among adolescents in four sub-Saharan African countries: associations with adverse childhood experiences
<p>Abstract</p> <p>Background</p> <p>Consumption of alcohol is associated with acute and chronic adverse health outcomes. There is a paucity of studies that explore the determinants of alcohol use among adolescents in sub-Saharan Africa and, in particular, that examine the effects of adverse childhood experiences on alcohol use.</p> <p>Methods</p> <p>The paper draws on nationally-representative data from 9,819 adolescents aged 12-19 years from Burkina Faso, Ghana, Malawi, and Uganda. Logistic regression models were employed to identify correlates of self-reported past-year drunkenness. Exposure to four adverse childhood experiences comprised the primary independent variables: living in a food-insecure household, living with a problem drinker, having been physically abused, and having been coerced into having sex. We controlled for age, religiosity, current schooling status, the household head's sex, living arrangements, place of residence, marital status, and country of survey. All analyses were conducted separately for males and females.</p> <p>Results</p> <p>At the bivariate level, all independent variables (except for coerced sex among males) were associated with the outcome variable. Overall, 9% of adolescents reported that they had been drunk in the 12 months preceding the survey. In general, respondents who had experienced an adverse event during childhood were more likely to report drunkenness. In the multivariate analysis, only two adverse childhood events emerged as significant predictors of self-reported past-year drunkenness among males: living in a household with a problem drinker before age 10, and being physically abused before age 10. For females, exposure to family-alcoholism, experience of physical abuse, and coerced sex increased the likelihood of reporting drunkenness in the last 12 months. The association between adverse events and reported drunkenness was more pronounced for females. For both males and females there was a graded relationship between the number of adverse events experienced and the proportion reporting drunkenness.</p> <p>Conclusions</p> <p>We find an association between experience of adverse childhood events and drunkenness among adolescents in four sub-Saharan African countries. The complex impacts of adverse childhood experiences on young people's development and behavior may have an important bearing on the effectiveness of interventions geared at reducing alcohol dependence among the youth.</p
Proteomic and Phospho-Proteomic Profile of Human Platelets in Basal, Resting State: Insights into Integrin Signaling
During atherogenesis and vascular inflammation quiescent platelets are activated to increase the surface expression and ligand affinity of the integrin αIIbβ3 via inside-out signaling. Diverse signals such as thrombin, ADP and epinephrine transduce signals through their respective GPCRs to activate protein kinases that ultimately lead to the phosphorylation of the cytoplasmic tail of the integrin αIIbβ3 and augment its function. The signaling pathways that transmit signals from the GPCR to the cytosolic domain of the integrin are not well defined. In an effort to better understand these pathways, we employed a combination of proteomic profiling and computational analyses of isolated human platelets. We analyzed ten independent human samples and identified a total of 1507 unique proteins in platelets. This is the most comprehensive platelet proteome assembled to date and includes 190 membrane-associated and 262 phosphorylated proteins, which were identified via independent proteomic and phospho-proteomic profiling. We used this proteomic dataset to create a platelet protein-protein interaction (PPI) network and applied novel contextual information about the phosphorylation step to introduce limited directionality in the PPI graph. This newly developed contextual PPI network computationally recapitulated an integrin signaling pathway. Most importantly, our approach not only provided insights into the mechanism of integrin αIIbβ3 activation in resting platelets but also provides an improved model for analysis and discovery of PPI dynamics and signaling pathways in the future
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