3’Nucleotidase/nuclease is required for Leishmania infantum clinical isolate susceptibility to miltefosine

Summary Background Miltefosine treatment failure in visceral leishmaniasis in Brazil has been associated with deletion of the miltefosine susceptibility locus (MSL) in Leishmania infantum. The MSL comprises four genes, 3′ -nucleotidase/nucleases (NUC1 and NUC2); helicase-like protein (HLP); and 3,2-trans-enoyl-CoA isomerase (TEI). Methods In this study CRISPR-Cas9 was used to either epitope tag or delete NUC1, NUC2, HLP and TEI, to investigate their role in miltefosine resistance mechanisms. Additionally, miltefosine transporter genes and miltefosine-mediated reactive oxygen species homeostasis were assessed in 26 L. infantum clinical isolates. A comparative lipidomic analysis was also performed to investigate the molecular basis of miltefosine resistance. Findings Deletion of both NUC1, NUC2 from the MSL was associated with a significant decrease in miltefosine susceptibility, which was restored after re-expression. Metabolomic analysis of parasites lacking the MSL or NUC1 and NUC2 identified an increase in the parasite lipid content, including ergosterol; these lipids may contribute to miltefosine resistance by binding the drug in the membrane. Parasites lacking the MSL are more resistant to lipid metabolism perturbation caused by miltefosine and NUC1 and NUC2 are involved in this pathway. Additionally, L. infantum parasites lacking the MSL isolated from patients who relapsed after miltefosine treatment were found to modulate nitric oxide accumulation in host macrophages. Interpretation Altogether, these data indicate that multifactorial mechanisms are involved in natural resistance to miltefosine in L. infantum and that the absence of the 3’nucleotidase/nuclease genes NUC1 and NUC2 contributes to the phenotype.publishersversionpublishe

The effects of caffeine on rugby passing accuracy while performing the Reactive Agility Test

This document is the Accepted Manuscript version of the following article: H. N. Assi, and L. Bottoms, ‘The effects of caffeine on rugby passing accuracy while performing the Reactive Agility Test’, Science & Sports, Vol. 29 (5): 275-281, October 2014, DOI: https://doi.org/10.1016/j.scispo.2014.07.012. This manuscript version is made available under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited, and is not altered, transformed, or built upon in any way.Aim.—Caffeine has been observed to improve performance of high-intensity and endurance exercise, but its effects on passing accuracy and reactive agility seen in intermittent high intensity team sports such as rugby and hockey are unclear. The purpose of this investigation was to determine the effect of ingesting caffeine on passing accuracy and agility speed before and after a simulated rugby protocol (SRP). Methods.—Nine male amateur rugby union players volunteered to participate in the study. The first visit participants undertook the multistage fitness test to estimate maximal oxygen consumption levels. On the second and third visits, a passing accuracy test (PAT) was undertaken which involved a modified reactive agility speed test that pressured the participants to pass into a target at the end of each run pre and post the 40-minute SRP. Participants ingested either 6 mg.kg.bw−1 of caffeine (CAF) or a placebo (PL) 60 minutes prior to the start of the SRP. Results.—CAF maintained sprint speed after the SRP whereas it decreased during PL trial. However, there were no effect of CAF on PAT scores (P > 0.05) nor was there an effect on RPE (P > 0.05). The results of the study lend some support to findings illustrating beneficial effect of caffeine ingestion before a simulated rugby protocol.Peer reviewe

Female chromosome X mosaicism is age-related and preferentially affects the inactivated X chromosome

To investigate large structural clonal mosaicism of chromosome X, we analysed the SNP microarray intensity data of 38,303 women from cancer genome-wide association studies (20,878 cases and 17,425 controls) and detected 124 mosaic X events42Mb in 97 (0.25%) women. Here we show rates for X-chromosome mosaicism are four times higher than mean autosomal rates; X mosaic events more often include the entire chromosome and participants with X events more likely harbour autosomal mosaic events. X mosaicism frequency increases with age (0.11% in 50-year olds; 0.45% in 75-year olds), as reported for Y and autosomes. Methylation array analyses of 33 women with X mosaicism indicate events preferentially involve the inactive X chromosome. Our results provide further evidence that the sex chromosomes undergo mosaic events more frequently than autosomes, which could have implications for understanding the underlying mechanisms of mosaic events and their possible contribution to risk for chronic diseases

Calculating potential evaporation from climate model data: a source of uncertainty for hydrological climate change impacts

Evaporation is an important part of the water balance of a catchment, and estimates of potential evaporation (PE) are an important input to hydrological models. When modelling the hydrological impacts of climate change, using data from climate models, present models generally do not provide direct estimates of PE from the land surface. Estimates thus have to be calculated from other climate variables, and many existing formulae can be applied. This paper compares the well-established, more physically-based but data-intensive, Penman-Monteith PE against a simple, temperature-based (T-based) PE, when calculated from readily-available monthly climate model data over Britain (for five global and eight regional climate models). The performance of the two PE formulations is compared to MORECS PE (a gridded dataset derived by the UK Met Office from weather observations, using a modified Penman-Monteith formulation) for the baseline period 1961-1990, and the changes in the two PE estimates between the 1970s and the 2080s are compared. The results show that the T-based PE matches MORECS PE better than does Penman-Monteith PE, for all the climate models studied. However, the changes in the two types of PE between the 1970s and 2080s are different, for each of the climate models, and these affect the modelled hydrological impacts. This is illustrated using three example catchments spread across Britain. The uncertainty introduced by the PE formulation is less than that due to the climate model, but could still be important for some applications

Formalizing O Notation in Isabelle/HOL

We describe a formalization of asymptotic O notation using the Isabelle/HOL proof assistant

Body and disease 2008: An integrated course teaching pathology, pharmacology, immunology and microbiology

Singapore General Hospital Proceedings18255-6

Theory and application of width bounded geometric separator

Abstract. We introduce the notion of the width bounded geometric separator and develop the techniques for the existence of the width bounded separator in any d-dimensional Euclidean space. The separator is applied in obtaining 2 O( √ n) time exact algorithms for a class of NPcomplete geometric problems, whose previous algorithms take n O( √ n) time [2,5,1]. One of those problems is the well known disk covering problem, which seeks to determine the minimal number of fixed size disks to cover n points on a plane [10]. They also include some NP-hard problems on disk graphs such as the maximum independent set problem, the vertex cover problem, and the minimum dominating set problem.