Fertilization in C. elegans requires an intact C-terminal RING finger in sperm protein SPE-42

<p>Abstract</p> <p>Background</p> <p>The <it>C. elegans </it>sperm protein SPE-42, a membrane protein of unknown structure and molecular function, is required for fertilization. Sperm from worms with <it>spe-42 </it>mutations appear normal but are unable to fertilize eggs. Sequence analysis revealed the presence of 8 conserved cysteine residues in the C-terminal cytoplasmic domain of this protein suggesting these residues form a zinc-coordinating RING finger structure.</p> <p>Results</p> <p>We made an <it>in silico </it>structural model of the SPE-42 RING finger domain based on primary sequence analysis and previously reported RING structures. To test the model, we created <it>spe-42 </it>transgenes coding for mutations in each of the 8 cysteine residues predicted to coordinate Zn⁺⁺ions in the RING finger motif. Transgenes were crossed into a <it>spe-42 </it>null background and protein function was measured by counting progeny. We found that all 8 cysteines are required for protein function. We also showed that sequence differences between the C-terminal 29 and 30 amino acids in <it>C. elegans </it>and <it>C. briggsae </it>SPE-42 following the RING finger domain are not responsible for the failure of the <it>C. briggsae </it>SPE-42 homolog to rescue <it>C. elegans spe-42 </it>mutants.</p> <p>Conclusions</p> <p>The results suggest that a <it>bona fide </it>RING domain is present at the C-terminus of the SPE-42 protein and that this motif is required for sperm-egg interactions during <it>C. elegans </it>fertilization. Our structural model of the RING domain provides a starting point for further structure-function analysis of this critical region of the protein. The C-terminal domain swap experiment suggests that the incompatibility between the <it>C. elegans </it>and <it>C. briggsae </it>SPE-42 proteins is caused by small amino acid differences outside the C-terminal domain.</p

User needs elicitation via analytic hierarchy process (AHP). A case study on a Computed Tomography (CT) scanner

Background: The rigorous elicitation of user needs is a crucial step for both medical device design and purchasing. However, user needs elicitation is often based on qualitative methods whose findings can be difficult to integrate into medical decision-making. This paper describes the application of AHP to elicit user needs for a new CT scanner for use in a public hospital. Methods: AHP was used to design a hierarchy of 12 needs for a new CT scanner, grouped into 4 homogenous categories, and to prepare a paper questionnaire to investigate the relative priorities of these. The questionnaire was completed by 5 senior clinicians working in a variety of clinical specialisations and departments in the same Italian public hospital. Results: Although safety and performance were considered the most important issues, user needs changed according to clinical scenario. For elective surgery, the five most important needs were: spatial resolution, processing software, radiation dose, patient monitoring, and contrast medium. For emergency, the top five most important needs were: patient monitoring, radiation dose, contrast medium control, speed run, spatial resolution. Conclusions: AHP effectively supported user need elicitation, helping to develop an analytic and intelligible framework of decision-making. User needs varied according to working scenario (elective versus emergency medicine) more than clinical specialization. This method should be considered by practitioners involved in decisions about new medical technology, whether that be during device design or before deciding whether to allocate budgets for new medical devices according to clinical functions or according to hospital department

Differences in Atherosclerotic Plaque Burden and Morphology Between Type 1 and 2 Diabetes as Assessed by Multislice Computed Tomography

OBJECTIVE It is unclear whether the coronary atherosclerotic plaque burden is similar in patients with type 1 and type 2 diabetes. By using multislice computed tomography (MSCT), the presence, degree, and morphology of coronary artery disease (CAD) in patients with type 1 and type 2 diabetes were compared. RESEARCH DESIGN AND METHODS Prospectively, coronary artery calcium (CAC) scoring and MSCT coronary angiography were performed in 135 asymptomatic patients (65 patients with type 1 diabetes and 70 patients with type 2 diabetes). The presence and extent of coronary atherosclerosis as well as plaque phenotype were assessed and compared between groups. RESULTS No difference was observed in average CAC score (217 +/- 530 vs. 174 +/- 361) or in the prevalence of coronary atherosclerosis (65% vs. 71%) in patients with type 1 and type 2 diabetes. However, the prevalence of obstructive atherosclerosis was higher in patients with type 2 diabetes (n = 24; 34%) compared with that in patients with type 1 diabetes (n = 11; 17%) (P = 0.02). In addition, a higher mean number of atherosclerotic and obstructive plaques was observed in patients with type 2 diabetes. In addition, the percentage of noncalcified plaques was higher in patients with type 2 (66%) versus type 1 diabetes (27%) (P <0.001), resulting in a higher plaque burden for each CAC score compared with that in type 1 diabetic patients. CONCLUSIONS Although CAC scores and the prevalence of coronary atherosclerosis were similar between patients with type 1 and type 2 diabetes, CAD was more extensive in the latter. Also, a relatively higher proportion of noncalcified plaques was observed in patients with type 2 diabetes. These observations may be valuable in the development of targeted management strategies adapted to diabetes typ

Novel clinical applications of state-of-the-art multi-slice computed tomography

Recent years have witnessed a rapid development of multi-slice computed tomography (MSCT) technology. The number of detector rows has increased from 4-slices to the current availability of 64-slice and even 320-slice systems. In addition, images are acquired with thinner slices and faster rotation times resulting in substantially improved image quality and diagnostic accuracy. Simultaneously, effective dose reduction acquisition techniques have been developed allowing considerable reduction of the radiation dose. Conceivably, these advancements may allow further expansion of the use of MSCT beyond the visual assessment of the presence or absence of significant coronary artery disease. Indeed, a particular advantage of the technique is that in addition to evaluation of the coronary arteries it also allows assessment of cardiac structures and function. The purpose of the current review is to discuss several novel applications of cardiac MSCT, including stenosis quantification, atherosclerotic plaque imaging and prognostification as well as imaging of left ventricular function, aortic and mitral valve anatomy using state-of-the-art technology

Atrial function in Fontan patients assessed by CMR: Relation with exercise capacity and long-term outcomes

Objective: To assess the role of atrial function on exercise capacity and clinical events in Fontan patients. Design: We included 96 Fontan patients from 6 tertiary centers, aged 12.8 (IQR 10.1–15.6) years, who underwent cardiac magnetic resonance imaging and cardiopulmonary exercise testing within 12 months of each other from 2004 to 2017. Intra-atrial lateral tunnel (ILT) and extracardiac conduit (ECC) patients were matched 1:1 with regard to age, gender and dominant ventricle. The pulmonary venous atrium was manually segmented in all phases and slices. Atrial function was assessed by volume-time curves. Furthermore, atrial longitudinal and circumferential feature tracking strain was assessed. We determined the relation between atrial function and exercise capacity, assessed by peak oxygen uptake and VE/VCO2 slope, and events (mortality, listing for transplant, re-intervention, arrhythmia) during follow-up. Results: Atrial maximal and minimal volumes did not differ between ILT and ECC patients. ECC patients had higher reservoir function (21.1 [16.4–28.0]% vs 18.2 [10.9–22.2]%, p = .03), lower conduit function and lower total circumferential strain (13.8 ± 5.1% vs 18.0 ± 8.7%, p = .01), compared to ILT patients. Only for ECC patients, a better late peak circumferential strain rate predicted better VE/VCO2 slope. No other parameter of atrial function predicted peak oxygen uptake or VE/VCO2 slope. During a median follow-up of 6.2 years,

Predictive Value of Multislice Computed Tomography Variables of Atherosclerosis for Ischemia on Stress-Rest Single Photon Emission Computed Tomography (SPECT)

BACKGROUND: -Previous studies have shown that the presence of stenosis alone on multislice computed tomography (MSCT) has a limited positive predictive value for the presence of ischemia on myocardial perfusion imaging (MPI). The purpose of this study was to assess which variables of atherosclerosis on MSCT angiography are related to ischemia on MPI. METHODS AND RESULTS: -Both MSCT and MPI were performed in 514 patients. On MSCT, the calcium score, degree of stenosis (>/=50% and >/=70% stenosis), plaque extent and location were determined. Plaque composition was classified as non-calcified, mixed or calcified. Ischemia was defined as a summed difference score >/=2 on a per patient basis. Ischemia was observed in 137 patients (27%). On a patient basis, multivariate analysis showed that the degree of stenosis (presence of >/=70% stenosis, OR 3.5), plaque extent and composition (mixed plaques >/=3, OR 1.7 and calcified plaques >/=3, OR 2.0) and location (atherosclerotic disease in left main coronary artery and/or proximal left anterior descending coronary artery, OR 1.6) were independent predictors for ischemia on MPI. In addition, MSCT variables of atherosclerosis such as plaque extent, composition and location had significant incremental value for the prediction of ischemia over the presence of >/=70% stenosis. CONCLUSIONS: -In addition to the degree of stenosis, MSCT variables of atherosclerosis describing plaque extent, composition and location are predictive of the presence of ischemia on MPI

Cerebral Perfusion and Aortic Stiffness Are Independent Predictors of White Matter Brain Atrophy in Type 1 Diabetic Patients Assessed With Magnetic Resonance Imaging

OBJECTIVE-To identify vascular mechanisms of brain atrophy in type 1 diabetes mellitus (DM) patients by investigating the relationship between brain volumes and cerebral perfusion and aortic stiffness using magnetic resonance imaging (MRI). RESEARCH DESIGN AND METHODS-Approval from the local institutional review board was obtained, and patients gave informed consent. Fifty-one type 1 DM patients (30 men; mean age 44 +/- 11 years; mean DM duration 23 +/- 12 years) and 34 age- and sex-matched healthy control subjects were prospectively enrolled. Exclusion criteria comprised hypertension, stroke, aortic disease, and standard MRI contraindications. White matter (WM) and gray matter (GM) brain volumes, total cerebral blood flow (tCBF), total brain perfusion, and aortic pulse wave velocity (PWV) were assessed using MRI. Multivariable linear regression analysis was used for statistics, with covariates age, sex, mean arterial pressure, BMI, smoking, heart rate, DM duration, and HbA(1c). RESULTS-Both WM and GM brain volumes were decreased in type 1 DM patients compared with control subjects (WM P = 0.04; respective GM P = 0.03). Total brain perfusion was increased in type 1 DM compared with control subjects (beta = -0.219, P < 0.05). Total CBF and aortic PWV predicted WM brain volume (beta = 0.352, P = 0.024 for tCBF; respective beta = 0.458, P = 0.016 for aortic PWV) in type 1 DM. Age was the independent predictor of GM brain volume (beta = -0.695, P < 0.001). CONCLUSIONS-Type 1 DM patients without hypertension showed WM and GM volume loss compared with control subjects concomitant with a relative increased brain perfusion. Total CBF and stiffness of the aorta independently predicted WM brain atrophy in type 1 DM. Only age predicted GM brain atrophy.Cardiovascular Aspects of Radiolog

Differences in ebullitive methane release from small, shallow ponds present challenges for scaling

Small, shallow waterbodies are potentially important sites of greenhouse gas release to the atmosphere. The role of ebullition may be enhanced here relative to larger and deeper systems, due to their shallow water, but these features remain relatively infrequently studied in comparison to larger systems.Herein,we quantify ebullitive release ofmethane (CH4) in small shallow ponds in three regions of North America and investigate the role of potential drivers. Shallow ponds exhibited open-water season ebullitive CH4 release rates as high as 40 mmol m–2 d–1, higher than previously reported for similar systems. Ebullitive release of CH4 varied by four orders of magnitude across our 15 study sites, with differences in flux rates both within and between regions. What is less clear are the drivers responsible for these differences. There were few relationships between open water–season ebullitive flux and physicochemical characteristics, including organic matter, temperature, and sulphate. Temperature was only weakly related to ebullitive CH4 release across the studywhen considering all observation intervals. Only four individual sites exhibited significant relationships between temperature and ebullitive CH4 release. Other sites were unresponsive to temperature, and region-specific factors may play a role. There is some evidence that where surface water sulphate concentrations are high, CH4 production and release may be suppressed. Missouri sites (n = 5) had characteristically low ebullitive CH4 release; here bioturbation could be important. While this work greatly expands the number of open-water season ebullition rates for small and shallow ponds, more research is needed to disentangle the role of different drivers. Further investigation of the potential thresholding behaviour of sulphate as a control on ebullitive CH4 release in lentic systems is one such opportunity. What is clear, however, is that efforts to scale emissions (e.g., as a function of temperature) must be undertaken with caution."Fieldwork at US and GHG analyses for the project were funded through an NSERC-DG awarded to CJW. Fieldwork and analysis at UW were funded through an NSERC-DG awarded to NJC. Fieldwork and nutrient analysis atMUwere funded by the Prairie Fork Charitable Endowment Trust to RLN."https://www.sciencedirect.com/science/article/pii/S004896972104760