197 research outputs found
Female Sexual Polymorphism and Fecundity Consequences of Male Mating Harassment in the Wild
Genetic and phenotypic variation in female response towards male mating attempts has been found in several laboratory studies, demonstrating sexually antagonistic co-evolution driven by mating costs on female fitness. Theoretical models suggest that the type and degree of genetic variation in female resistance could affect the evolutionary outcome of sexually antagonistic mating interactions, resulting in either rapid development of reproductive isolation and speciation or genetic clustering and female sexual polymorphisms. However, evidence for genetic variation of this kind in natural populations of non-model organisms is very limited. Likewise, we lack knowledge on female fecundity-consequences of matings and the degree of male mating harassment in natural settings. Here we present such data from natural populations of a colour polymorphic damselfly. Using a novel experimental technique of colour dusting males in the field, we show that heritable female colour morphs differ in their propensity to accept male mating attempts. These morphs also differ in their degree of resistance towards male mating attempts, the number of realized matings and in their fecundity-tolerance to matings and mating attempts. These results show that there may be genetic variation in both resistance and tolerance to male mating attempts (fitness consequences of matings) in natural populations, similar to the situation in plant-pathogen resistance systems. Male mating harassment could promote the maintenance of a sexual mating polymorphism in females, one of few empirical examples of sympatric genetic clusters maintained by sexual conflict
A Triple Protostar System Formed via Fragmentation of a Gravitationally Unstable Disk
Binary and multiple star systems are a frequent outcome of the star formation
process, and as a result, almost half of all sun-like stars have at least one
companion star. Theoretical studies indicate that there are two main pathways
that can operate concurrently to form binary/multiple star systems: large scale
fragmentation of turbulent gas cores and filaments or smaller scale
fragmentation of a massive protostellar disk due to gravitational instability.
Observational evidence for turbulent fragmentation on scales of 1000~AU has
recently emerged. Previous evidence for disk fragmentation was limited to
inferences based on the separations of more-evolved pre-main sequence and
protostellar multiple systems. The triple protostar system L1448 IRS3B is an
ideal candidate to search for evidence of disk fragmentation. L1448 IRS3B is in
an early phase of the star formation process, likely less than 150,000 years in
age, and all protostars in the system are separated by 200~AU. Here we
report observations of dust and molecular gas emission that reveal a disk with
spiral structure surrounding the three protostars. Two protostars near the
center of the disk are separated by 61 AU, and a tertiary protostar is
coincident with a spiral arm in the outer disk at a 183 AU separation. The
inferred mass of the central pair of protostellar objects is 1 M,
while the disk surrounding the three protostars has a total mass of 0.30
M_{\sun}. The tertiary protostar itself has a minimum mass of 0.085
M. We demonstrate that the disk around L1448 IRS3B appears susceptible
to disk fragmentation at radii between 150~AU and 320~AU, overlapping with the
location of the tertiary protostar. This is consistent with models for a
protostellar disk that has recently undergone gravitational instability,
spawning one or two companion stars.Comment: Published in Nature on Oct. 27th. 24 pages, 8 figure
Ecological Niche Dimensionality and the Evolutionary Diversification of Stick Insects
The degree of phenotypic divergence and reproductive isolation between taxon pairs can vary quantitatively, and often increases as evolutionary divergence proceeds through various stages, from polymorphism to population differentiation, ecotype and race formation, speciation, and post-speciational divergence. Although divergent natural selection promotes divergence, it does not always result in strong differentiation. For example, divergent selection can fail to complete speciation, and distinct species pairs sometimes collapse (‘speciation in reverse’). Widely-discussed explanations for this variability concern genetic architecture, and the geographic arrangement of populations. A less-explored possibility is that the degree of phenotypic and reproductive divergence between taxon pairs is positively related to the number of ecological niche dimensions (i.e., traits) subject to divergent selection. Some data supporting this idea stem from laboratory experimental evolution studies using Drosophila, but tests from nature are lacking. Here we report results from manipulative field experiments in natural populations of herbivorous Timema stick insects that are consistent with this ‘niche dimensionality’ hypothesis. In such insects, divergent selection between host plants might occur for cryptic colouration (camouflage to evade visual predation), physiology (to detoxify plant chemicals), or both of these niche dimensions. We show that divergent selection on the single niche dimension of cryptic colouration can result in ecotype formation and intermediate levels of phenotypic and reproductive divergence between populations feeding on different hosts. However, greater divergence between a species pair involved divergent selection on both niche dimensions. Although further replication of the trends reported here is required, the results suggest that dimensionality of selection may complement genetic and geographic explanations for the degree of diversification in nature
Validation of Case-Finding Algorithms Derived from Administrative Data for Identifying Adults Living with Human Immunodeficiency Virus Infection
OBJECTIVE: We sought to validate a case-finding algorithm for human immunodeficiency virus (HIV) infection using administrative health databases in Ontario, Canada. METHODS: We constructed 48 case-finding algorithms using combinations of physician billing claims, hospital and emergency room separations and prescription drug claims. We determined the test characteristics of each algorithm over various time frames for identifying HIV infection, using data abstracted from the charts of 2,040 randomly selected patients receiving care at two medical practices in Toronto, Ontario as the reference standard. RESULTS: With the exception of algorithms using only a single physician claim, the specificity of all algorithms exceeded 99%. An algorithm consisting of three physician claims over a three year period had a sensitivity and specificity of 96.2% (95% CI 95.2%-97.9%) and 99.6% (95% CI 99.1%-99.8%), respectively. Application of the algorithm to the province of Ontario identified 12,179 HIV-infected patients in care for the period spanning April 1, 2007 to March 31, 2009. CONCLUSIONS: Case-finding algorithms generated from administrative data can accurately identify adults living with HIV. A relatively simple "3 claims in 3 years" definition can be used for assembling a population-based cohort and facilitating future research examining trends in health service use and outcomes among HIV-infected adults in Ontario
Developing community-driven quality improvement initiatives to enhance chronic disease care in Indigenous communities in Canada : the FORGE AHEAD program protocol
BACKGROUND: Given the dramatic rise and impact of chronic diseases and gaps in care in Indigenous peoples in Canada, a shift from the dominant episodic and responsive healthcare model most common in First Nations communities to one that places emphasis on proactive prevention and chronic disease management is urgently needed. METHODS: The Transformation of Indigenous Primary Healthcare Delivery (FORGE AHEAD) Program partners with 11 First Nations communities across six provinces in Canada to develop and evaluate community-driven quality improvement (QI) initiatives to enhance chronic disease care. FORGE AHEAD is a 5-year research program (2013-2017) that utilizes a pre-post mixed-methods observational design rooted in participatory research principles to work with communities in developing culturally relevant innovations and improved access to available services. This intensive program incorporates a series of 10 inter-related and progressive program activities designed to foster community-driven initiatives with type 2 diabetes mellitus as the action disease. Preparatory activities include a national community profile survey, best practice and policy literature review, and readiness tool development. Community-level intervention activities include community and clinical readiness consultations, development of a diabetes registry and surveillance system, and QI activities. With a focus on capacity building, all community-level activities are driven by trained community members who champion QI initiatives in their community. Program wrap-up activities include readiness tool validation, cost-analysis and process evaluation. In collaboration with Health Canada and the Aboriginal Diabetes Initiative, scale-up toolkits will be developed in order to build on lessons-learned, tools and methods, and to fuel sustainability and spread of successful innovations. DISCUSSION: The outcomes of this research program, its related cost and the subsequent policy recommendations, will have the potential to significantly affect future policy decisions pertaining to chronic disease care in First Nations communities in Canada. TRIAL REGISTRATION: Current ClinicalTrial.gov protocol ID NCT02234973 . Date of Registration: July 30, 2014
The effects of β-glucan on human immune and cancer cells
Non-prescriptional use of medicinal herbs among cancer patients is common around the world. The alleged anti-cancer effects of most herbal extracts are mainly based on studies derived from in vitro or in vivo animal experiments. The current information suggests that these herbal extracts exert their biological effect either through cytotoxic or immunomodulatory mechanisms. One of the active compounds responsible for the immune effects of herbal products is in the form of complex polysaccharides known as β-glucans. β-glucans are ubiquitously found in both bacterial or fungal cell walls and have been implicated in the initiation of anti-microbial immune response. Based on in vitro studies, β-glucans act on several immune receptors including Dectin-1, complement receptor (CR3) and TLR-2/6 and trigger a group of immune cells including macrophages, neutrophils, monocytes, natural killer cells and dendritic cells. As a consequence, both innate and adaptive response can be modulated by β-glucans and they can also enhance opsonic and non-opsonic phagocytosis. In animal studies, after oral administration, the specific backbone 1→3 linear β-glycosidic chain of β-glucans cannot be digested. Most β-glucans enter the proximal small intestine and some are captured by the macrophages. They are internalized and fragmented within the cells, then transported by the macrophages to the marrow and endothelial reticular system. The small β-glucans fragments are eventually released by the macrophages and taken up by other immune cells leading to various immune responses. However, β-glucans of different sizes and branching patterns may have significantly variable immune potency. Careful selection of appropriate β-glucans is essential if we wish to investigate the effects of β-glucans clinically. So far, no good quality clinical trial data is available on assessing the effectiveness of purified β-glucans among cancer patients. Future effort should direct at performing well-designed clinical trials to verify the actual clinical efficacy of β-glucans or β-glucans containing compounds
Multiple Interferon Stimulated Genes Synergize with the Zinc Finger Antiviral Protein to Mediate Anti-Alphavirus Activity
The zinc finger antiviral protein (ZAP) is a host factor that mediates inhibition of viruses in the Filoviridae, Retroviridae and Togaviridae families. We previously demonstrated that ZAP blocks replication of Sindbis virus (SINV), the prototype Alphavirus in the Togaviridae family at an early step prior to translation of the incoming genome and that synergy between ZAP and one or more interferon stimulated genes (ISGs) resulted in maximal inhibitory activity. The present study aimed to identify those ISGs that synergize with ZAP to mediate Alphavirus inhibition. Using a library of lentiviruses individually expressing more than 350 ISGs, we screened for inhibitory activity in interferon defective cells with or without ZAP overexpression. Confirmatory tests of the 23 ISGs demonstrating the largest infection reduction in combination with ZAP revealed that 16 were synergistic. Confirmatory tests of all potentially synergistic ISGs revealed 15 additional ISGs with a statistically significant synergistic effect in combination with ZAP. These 31 ISGs are candidates for further mechanistic studies. The number and diversity of the identified ZAP-synergistic ISGs lead us to speculate that ZAP may play an important role in priming the cell for optimal ISG function
Staff understanding of recovery-orientated mental health practice: a systematic review and narrative synthesis
Background: Mental health policy is for staff to transform their practice towards a recovery orientation. Staff understanding of recovery-orientated practice will influence the implementation of this policy. The aim of this study was to conduct a systematic review and narrative synthesis of empirical studies identifying clinician and manager conceptualisations of recovery-orientated practice.
Methods: A systematic review of empirical primary research was conducted. Data sources were online databases (n = 8), journal table of contents (n = 5), internet, expert consultation (n = 13), reference lists of included studies and references to included studies. Narrative synthesis was used to integrate the findings.
Results: A total of 10,125 studies were screened, 245 full papers were retrieved, and 22 were included (participants, n = 1163). The following three conceptualisations of recovery-orientated practice were identified: clinical recovery, personal recovery and service-defined recovery. Service-defined recovery is a new conceptualisation which translates recovery into practice according to the goals and financial needs of the organisation.
Conclusions: Organisational priorities influence staff understanding of recovery support. This influence is leading to the emergence of an additional meaning of recovery. The impact of service-led approaches to operationalising recovery-orientated practice has not been evaluated.
Trial Registration: The protocol for the review was pre-registered (PROSPERO 2013: CRD42013005942)
Neoadjuvant continuous infusion of weekly 5-fluorouracil and escalating doses of oxaliplatin plus concurrent radiation in locally advanced oesophageal squamous cell carcinoma: results of a phase I/II trial
Oxaliplatin and 5-fluorouracil have a significant activity in locally advanced oesophageal squamous cell cancer (OSCC). However, their optimal dosage and efficacy when combined with concurrent radiotherapy as neoadjuvant treatment are unknown. This non-randomised, phase I/II study aimed to define the maximum tolerated dose (MTD) and assessed the histopathological tumour response rate to neoadjuvant oxaliplatin in weekly escalating doses (40, 45, 50 mg m−2) and continuous infusional 5-fluorouracil (CI-5FU; 225 mg m−2) plus concurrent radiotherapy. Patients had resectable OSCC. Resection was scheduled for 4–6 weeks after chemoradiotherapy. During phase I (dose escalation; n=19), weekly oxaliplatin 45 mg m−2 plus CI-5FU 225 mg m−2 was established as the MTD and was the recommended dosage for phase II. Oesophageal mucositis was the dose-limiting toxicity at higher doses. During phase II, histopathological responses (<10% residual tumour cells within the specimen) were observed in 10 of 16 patients (63%; 95% confidence interval: 39–82%). Overall, 16 of the 25 patients (64%) who underwent resection had a histopathological response; tumour-free resection (R0) was achieved in 80%. Neoadjuvant weekly oxaliplatin 45 mg m−2 plus CI-5FU 225 mg m−2 with concurrent radiotherapy provides promising histological response rates and R0 resection rates in locally advanced OSCC
Explanatory factors for first and second-generation non-western women’s inadequate prenatal care utilisation: a prospective cohort study
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