Mycobacterium tuberculosis type VII secretion system effectors differentially impact the ESCRT endomembrane damage response

Mycobacterium tuberculosis causes tuberculosis, which kills more people than any other infection. M. tuberculosis grows in macrophages, cells that specialize in engulfing and degrading microorganisms. Like many intracellular pathogens, in order to cause disease, M. tuberculosis damages the membrane-bound compartment (phagosome) in which it is enclosed after macrophage uptake. Recent work showed that when chemicals damage this type of intracellular compartment, cells rapidly detect and repair the damage, using machinery called the endosomal sorting complex required for transport (ESCRT). Therefore, we hypothesized that ESCRT might also respond to pathogen-induced damage. At the same time, our previous work showed that the EsxG-EsxH heterodimer of M. tuberculosis can inhibit ESCRT, raising the possibility that M. tuberculosis impairs this host response. Here, we show that ESCRT is recruited to damaged M. tuberculosis phagosomes and that EsxG-EsxH undermines ESCRT-mediated endomembrane repair. Thus, our studies demonstrate a battle between host and pathogen over endomembrane integrity.Intracellular pathogens have varied strategies to breach the endolysosomal barrier so that they can deliver effectors to the host cytosol, access nutrients, replicate in the cytoplasm, and avoid degradation in the lysosome. In the case of Mycobacterium tuberculosis, the bacterium perforates the phagosomal membrane shortly after being taken up by macrophages. Phagosomal damage depends upon the mycobacterial ESX-1 type VII secretion system (T7SS). Sterile insults, such as silica crystals or membranolytic peptides, can also disrupt phagosomal and endolysosomal membranes. Recent work revealed that the host endosomal sorting complex required for transport (ESCRT) machinery rapidly responds to sterile endolysosomal damage and promotes membrane repair. We hypothesized that ESCRTs might also respond to pathogen-induced phagosomal damage and that M. tuberculosis could impair this host response. Indeed, we found that ESCRT-III proteins were recruited to M. tuberculosis phagosomes in an ESX-1-dependent manner. We previously demonstrated that the mycobacterial effectors EsxG/TB9.8 and EsxH/TB10.4, both secreted by the ESX-3 T7SS, can inhibit ESCRT-dependent trafficking of receptors to the lysosome. Here, we additionally show that ESCRT-III recruitment to sites of endolysosomal damage is antagonized by EsxG and EsxH, both within the context of M. tuberculosis infection and sterile injury. Moreover, EsxG and EsxH themselves respond within minutes to membrane damage in a manner that is independent of calcium and ESCRT-III recruitment. Thus, our study reveals that T7SS effectors and ESCRT participate in a series of measures and countermeasures for control of phagosome integrity

Improving Class Pace for Deaf and Hard-of-Hearing Students

Following multimedia lectures in mainstream classrooms in university education is challenging for deaf and hard-of-hearing (DHH) students even when they are provided accommodations to best address their individual needs. Due to multiple visual sources of information (teacher, slides, interpreter, blackboard), these students struggle to divide their attention among several simultaneous sources of input, which may result in their missing important parts of the lecture content; as a result, DHH students’ access to information can be limited in comparison to that of their hearing peers, and so their academic achievements may be impacted. This paper introduces SlidePacer, a tool aimed at improving coordination between the instructor’s speech, the sign language interpretation of the lecture and the slide projection change. The goal of this software is to prevent DHH students’ loss of information by promoting an adequate pace of the lecture, which can contribute to their learning and academic achievements. We conclude with discussion of future work

Patient and researcher perspectives on facilitating patient and public involvement in rheumatology research

No abstract available

Principal component-based image segmentation: a new approach to outline in vitro cell colonies

The in vitro clonogenic assay is a technique to study the ability of a cell to form a colony in a culture dish. By optical imaging, dishes with stained colonies can be scanned and assessed digitally. Identification, segmentation and counting of stained colonies play a vital part in high-throughput screening and quantitative assessment of biological assays. Image processing of such pictured/scanned assays can be affected by image/scan acquisition artifacts like background noise and spatially varying illumination, and contaminants in the suspension medium. Although existing approaches tackle these issues, the segmentation quality requires further improvement, particularly on noisy and low contrast images. In this work, we present an objective and versatile machine learning procedure to amend these issues by characterizing, extracting and segmenting inquired colonies using principal component analysis, k-means clustering and a modified watershed segmentation algorithm. The intention is to automatically identify visible colonies through spatial texture assessment and accordingly discriminate them from background in preparation for successive segmentation. The proposed segmentation algorithm yielded a similar quality as manual counting by human observers. High F1 scores (>0.9) and low root-mean-square errors (around 14%) underlined good agreement with ground truth data. Moreover, it outperformed a recent state-of-the-art method. The methodology will be an important tool in future cancer research applications

Principal component-based image segmentation: a new approach to outline in vitro cell colonies

publishedVersio

Identifying implementation bottlenecks for maternal and newborn health interventions in rural districts of the United Republic of Tanzania.

OBJECTIVE: To estimate effective coverage of maternal and newborn health interventions and to identify bottlenecks in their implementation in rural districts of the United Republic of Tanzania. METHODS: Cross-sectional data from households and health facilities in Tandahimba and Newala districts were used in the analysis. We adapted Tanahashi's model to estimate intervention coverage in conditional stages and to identify implementation bottlenecks in access, health facility readiness and clinical practice. The interventions studied were syphilis and pre-eclampsia screening, partograph use, active management of the third stage of labour and postpartum care. FINDINGS: Effective coverage was low in both districts, ranging from only 3% for postpartum care in Tandahimba to 49% for active management of the third stage of labour in Newala. In Tandahimba, health facility readiness was the largest bottleneck for most interventions, whereas in Newala, it was access. Clinical practice was another large bottleneck for syphilis screening in both districts. CONCLUSION: The poor effective coverage of maternal and newborn health interventions in rural districts of the United Republic of Tanzania reinforces the need to prioritize health service quality. Access to high-quality local data by decision-makers would assist planning and prioritization. The approach of estimating effective coverage and identifying bottlenecks described here could facilitate progress towards universal health coverage for any area of care and in any context

Platelet anesthesia with nitric oxide with or without eptifibatide during cardiopulmonary bypass in baboons

AbstractObjective:This study tested the hypothesis that nitric oxide or nitric oxide and eptifibatide (Integrilin) reversibly inhibit platelet activation and consumption during cardiopulmonary bypass and rapidly restore platelet numbers and function after bypass. Methods: Nitric oxide, a short-acting, reversible platelet inhibitor, was studied with and without eptifibatide, a short-acting, reversible glycoprotein IIb/IIIa inhibitor, in 21 baboons that underwent 60 minutes of normothermic cardiopulmonary bypass with peripheral cannulas. A control group, a group that received 80 ppm nitric oxide, and a group that received both nitric oxide and eptifibatide were studied. Blood samples were obtained at several time points to determine platelet count, aggregation in response to adenosine diphosphate, and levels of β-thromboglobulin, prothrombin fragment 1.2, and thrombin-antithrombin complex. Template bleeding times were measured before and at 4 intervals after cardiopulmonary bypass. Results: Both nitric oxide and the combination of the 2 drugs significantly attenuated platelet consumption, improved postbypass function, and reduced plasma β-thromboglobulin release with respect to values in control animals. Both nitric oxide and the combination restored baseline bleeding times 55 minutes after cardiopulmonary bypass ended. No significant differences between nitric oxide and the combination were found for any measurement. Conclusion: Nitric oxide with or without eptifibatide protects platelets during cardiopulmonary bypass and accelerates restoration of normal bleeding times after operation in a baboon model. Although nitric oxide and eptifibatide reversibly inhibit platelets by different mechanisms, in the absence of a wound no synergistic effect was demonstrated. (J Thorac Cardiovasc Surg 1999;117: 987-93