851 research outputs found
Uptake of home-based voluntary HIV testing in sub-Saharan Africa: a systematic review and meta-analysis
Improving access to HIV testing is a key priority in scaling up HIV treatment and prevention services. Home-based voluntary counselling and testing (HBT) as an approach to delivering wide-scale HIV testing is explored here
In vitro selectivity, in vivo biodistribution and tumour uptake of annexin V radiolabelled with a positron emitting radioisotope
The availability of a noninvasive method to detect and quantify apoptosis in tumours will enable tumour response to several cancer therapies to be assessed. We have synthesised two radiotracers, annexin V and the N-succinimidyl-3-iodobenzoic acid (SIB) derivative of annexin V, labelled with radio-iodine (124I and 125I) and provided proof of the concept by assessing specific binding and biodistribution of these probes to apoptotic cells and tumours. We have also assessed the tumour uptake of [124I]annexin V in a mouse model of apoptosis. RIF-1 cells induced to undergo apoptosis in vitro showed a drug concentration-dependent increased binding of [125I]annexin V and [125I]SIBâannexin V. In the same model system, there was an increase in terminal deoxynucleotidyl transferase-mediated nick end labelling (TUNEL)-positive cells and a decrease in clonogenic survival. Radiotracer binding was completely inhibited by preincubation with unlabelled annexin V. In RIF-1 tumour-bearing mice, rapid distribution of [125I]SIBâannexin V-derived radioactivity to kidneys was observed and the radiotracer accumulated in urine. The binding of [125I]SIBâannexin V to RIF-1 tumours increased by 2.3-fold at 48âh after a single intraperitoneal injection of 5-fluorouracil (165âmgâkgâ1 body weight), compared to a 4.4-fold increase in TUNEL-positive cells measured by immunostaining. Positron emission tomography images with both radiotracers demonstrated intense localisation in the kidneys and bladder. Unlike [124I]SIBâannexin V, [124I]annexin V also showed localisation in the thyroid region presumably due to deiodination of the radiolabel. [124I]SIBâannexin V is an attractive candidate for in vivo imaging of apoptosis by PET
Accuracy of direct genomic values in Holstein bulls and cows using subsets of SNP markers
Background: At the current price, the use of high-density single nucleotide polymorphisms (SNP) genotyping assays in genomic selection of dairy cattle is limited to applications involving elite sires and dams. The objective of this study was to evaluate the use of low-density assays to predict direct genomic value (DGV) on five milk production traits, an overall conformation trait, a survival index, and two profit index traits (APR, ASI). Methods. Dense SNP genotypes were available for 42,576 SNP for 2,114 Holstein bulls and 510 cows. A subset of 1,847 bulls born between 1955 and 2004 was used as a training set to fit models with various sets of pre-selected SNP. A group of 297 bulls born between 2001 and 2004 and all cows born between 1992 and 2004 were used to evaluate the accuracy of DGV prediction. Ridge regression (RR) and partial least squares regression (PLSR) were used to derive prediction equations and to rank SNP based on the absolute value of the regression coefficients. Four alternative strategies were applied to select subset of SNP, namely: subsets of the highest ranked SNP for each individual trait, or a single subset of evenly spaced SNP, where SNP were selected based on their rank for ASI, APR or minor allele frequency within intervals of approximately equal length. Results: RR and PLSR performed very similarly to predict DGV, with PLSR performing better for low-density assays and RR for higher-density SNP sets. When using all SNP, DGV predictions for production traits, which have a higher heritability, were more accurate (0.52-0.64) than for survival (0.19-0.20), which has a low heritability. The gain in accuracy using subsets that included the highest ranked SNP for each trait was marginal (5-6%) over a common set of evenly spaced SNP when at least 3,000 SNP were used. Subsets containing 3,000 SNP provided more than 90% of the accuracy that could be achieved with a high-density assay for cows, and 80% of the high-density assay for young bulls. Conclusions: Accurate genomic evaluation of the broader bull and cow population can be achieved with a single genotyping assays containing ⌠3,000 to 5,000 evenly spaced SNP
Chlamydia trachomatis ompA Variants in Trachoma: What Do They Tell Us?
Trachoma is an important cause of blindness resulting from transmission of the bacterium Chlamydia trachomatis. One way to understand better how this infection is transmitted and how the human immune system controls it is to study the strains of bacteria associated with infection. Comparing strains before and after treatment might help us learn if someone has a new infection or the same one as before. Identifying differences between disease-causing strains should help us understand how infection leads to disease and how the human host defences work. We chose to study variation in the chlamydial gene ompA because it determines the protein MOMP, one of the leading candidates for inclusion in a vaccine to prevent trachoma. If immunity to MOMP is important in natural trachoma infections, we would expect to find evidence of this in the way the strains varied. We did not find this, but instead found that two common strains seemed to cause different types of disease. Although their MOMPs were very slightly different, this did not really explain the differences. We conclude that methods of typing strains going beyond the ompA gene will be needed to help us understand the interaction between Chlamydia and its human host
An exploratory randomised controlled trial of a premises-level intervention to reduce alcohol-related harm including violence in the United Kingdom
<b>Background</b><p></p>
To assess the feasibility of a randomised controlled trial of a licensed premises intervention to reduce severe intoxication and disorder; to establish effect sizes and identify appropriate approaches to the development and maintenance of a rigorous research design and intervention implementation.<p></p>
<b>Methods</b><p></p>
An exploratory two-armed parallel randomised controlled trial with a nested process evaluation. An audit of risk factors and a tailored action plan for high risk premises, with three month follow up audit and feedback. Thirty-two premises that had experienced at least one assault in the year prior to the intervention were recruited, match paired and randomly allocated to control or intervention group. Police violence data and data from a street survey of study premisesâ customers, including measures of breath alcohol concentration and surveyor rated customer intoxication, were used to assess effect sizes for a future definitive trial. A nested process evaluation explored implementation barriers and the fidelity of the intervention with key stakeholders and senior staff in intervention premises using semi-structured interviews.<p></p>
<b>Results</b><p></p>
The process evaluation indicated implementation barriers and low fidelity, with a reluctance to implement the intervention and to submit to a formal risk audit. Power calculations suggest the intervention effect on violence and subjective intoxication would be raised to significance with a study size of 517 premises.<p></p>
<b>Conclusions</b><p></p>
It is methodologically feasible to conduct randomised controlled trials where licensed premises are the unit of allocation. However, lack of enthusiasm in senior premises staff indicates the need for intervention enforcement, rather than voluntary agreements, and on-going strategies to promote sustainability
Effects of PREPARE, a Multi-component, School-Based HIV and Intimate Partner Violence (IPV) Prevention Programme on Adolescent Sexual Risk Behaviour and IPV : Cluster Randomised Controlled Trial
Young South Africans, especially women, are at high risk of HIV. We evaluated the effects of PREPARE, a multi-component, school-based HIV prevention intervention to delay sexual debut, increase condom use and decrease intimate partner violence (IPV) among young adolescents. We conducted a cluster RCT among Grade eights in 42 high schools. The intervention comprised education sessions, a school health service and a school sexual violence prevention programme. Participants completed questionnaires at baseline, 6 and 12 months. Regression was undertaken to provide ORs or coefficients adjusted for clustering. Of 6244 sampled adolescents, 55.3 % participated. At 12 months there were no differences between intervention and control arms in sexual risk behaviours. Participants in the intervention arm were less likely to report IPV victimisation (35.1 vs. 40.9 %; OR 0.77, 95 % CI 0.61-0.99; t(40) = 2.14) suggesting the intervention shaped intimate partnerships into safer ones, potentially lowering the risk for HIV
Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at â s = 8 TeV with the ATLAS detector
Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fbâ1 of â s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente
A hierarchical network approach for modeling Rift Valley fever epidemics with applications in North America
Rift Valley fever is a vector-borne zoonotic disease which causes high
morbidity and mortality in livestock. In the event Rift Valley fever virus is
introduced to the United States or other non-endemic areas, understanding the
potential patterns of spread and the areas at risk based on disease vectors and
hosts will be vital for developing mitigation strategies. Presented here is a
general network-based mathematical model of Rift Valley fever. Given a lack of
empirical data on disease vector species and their vector competence, this
discrete time epidemic model uses stochastic parameters following several PERT
distributions to model the dynamic interactions between hosts and likely North
American mosquito vectors in dispersed geographic areas. Spatial effects and
climate factors are also addressed in the model. The model is applied to a
large directed asymmetric network of 3,621 nodes based on actual farms to
examine a hypothetical introduction to some counties of Texas, an important
ranching area in the United States of America (U.S.A.). The nodes of the
networks represent livestock farms, livestock markets, and feedlots, and the
links represent cattle movements and mosquito diffusion between different
nodes. Cattle and mosquito (Aedes and Culex) populations are treated with
different contact networks to assess virus propagation. Rift Valley fever virus
spread is assessed under various initial infection conditions (infected
mosquito eggs, adults or cattle). A surprising trend is fewer initial
infectious organisms result in a longer delay before a larger and more
prolonged outbreak. The delay is likely caused by a lack of herd immunity while
the infections expands geographically before becoming an epidemic involving
many dispersed farms and animals almost simultaneously
Is drinking water a risk factor for endemic cryptosporidiosis? A case-control study in the immunocompetent general population of the San Francisco Bay Area
BACKGROUND: Cryptosporidiosis, caused by Cryptosporidium, is an enteric illness that has received much attention as an infection of immunocompromised persons as well as in community outbreaks (frequently waterborne). There are, however, no studies of the risk factors for sporadic community-acquired cryptosporidiosis in the immunocompetent US population. We undertook a case-control study in the San Francisco Bay Area as part of a national study sponsored by the Centers for Disease Control and Prevention to ascertain the major routes of transmission for endemic cryptosporidiosis, with an emphasis on evaluating risk from drinking water. METHODS: Cases were recruited from a population-based, active surveillance system and age-matched controls were recruited using sequential random-digit dialing. Cases (n = 26) and controls (n = 62) were interviewed by telephone using a standardized questionnaire that included information about the following exposures: drinking water, recreational water, food items, travel, animal contact, and person-to-person fecal contact, and (for adults) sexual practices. RESULTS: In multivariate conditional logistic regression analyses no significant association with drinking water was detected. The major risk factor for cryptosporidiosis in the San Francisco Bay Area was travel to another country (matched odds ratio [95% confidence interval]: 24.1 [2.6, 220]). CONCLUSION: The results of this study do not support the hypothesis that drinking water is an independent risk factor for cryptosporidiosis among the immunocompetent population. These findings should be used to design larger studies of endemic cryptosporidiosis to elucidate the precise mechanisms of transmission, whether waterborne or other
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