Search

Background: Multiparametric MRI provides assessment of functional and structural parameters in kidney allografts. It offers a non‐invasive alternative to the current reference standard of kidney biopsy. Purpose: To evaluate the diagnostic and prognostic utility of MRI parameters in the assessment of allograft function in the first 3‐months post‐transplantation. Study Type: Prospective. Subjects: 32 transplant recipients (54 ± 17 years, 20 females), divided into two groups according to estimated glomerular filtration rate (eGFR) at 3‐months post‐transplantation: inferior graft function (IGF; eGFR<45 mL/min/1.73 m2, n = 10) and superior graft function (SGF; eGFR ≥ 45 mL/min/1.73 m2, n = 22). Further categorization was based on the need for hemodialysis (C1) and decrease in s‐creatinine (C2) at 1‐week post‐transplantation: delayed‐graft‐function (DGF: n = 4 C1, n = 10 C2) and early graft‐function (EGF: n = 28 C1, n = 22 C2). Field Strength/Sequence: 3‐T, pseudo‐continuous arterial spin labeling, T1‐mapping, and diffusion‐weighted imaging. Assessment: Multiparametric MRI was evaluated at 1‐week in all patients and 3‐months after transplantation in 28 patients. Renal blood flow (RBF), diffusion coefficients (ADC, ΔADC, D, ∆D, D*, flowing fraction f), T1 and ∆T1 were calculated in cortex and medulla. The diagnostic and prognostic value of these parameters, obtained at 3‐months and 1‐week post‐transplantation, respectively, was evaluated in the cortex to discriminate between DGF and EGF, and between SGF and IGF. Statistical Tests: Logistic regression, receiver‐operating‐characteristics, area‐under‐the‐curve (AUC), confidence intervals (CIs), analysis‐of‐variance, t‐test, Wilcoxon‐Mann–Whitney test, Fisher's exact test, Pearson's correlation. P‐value<0.05 was considered significant. Results: DGF patients exhibited significantly lower cortical RBF and f and higher D*. The diagnostic value of MRI for detecting DGF was excellent (AUC = 100%). Significant differences between patients with IGF and SGF were found in RBF, ∆T1, and ∆D. Multiparametric MRI showed higher diagnostic (AUC = 95.32%; CI: 88%–100%) and prognostic (AUC = 97.47%, CI: 92%–100%) values for detecting IGF than eGFR (AUC = 89.50%, CI: 79%–100%). Data Conclusion: Multiparametric MRI may show high diagnostic and prognostic value in transplanted patients, yielding better results compared to eGFR measurements. Level of Evidence: 2 Technical Efficacy: Stage 1 [ABSTRACT FROM AUTHOR]

Background: Urinary tract infections (UTIs) are very common worldwide. According to their symptomatology, these infections are classified as pyelonephritis, cystitis, or asymptomatic bacteriuria (AB). Approximately 75–95% of UTIs are caused by uropathogenic Escherichia coli (UPEC), which is an extraintestinal bacterium that possesses virulence factors for bacterial adherence and invasion in the urinary tract. In addition, UPEC possesses type 6 secretion systems (T6SS) as virulence mechanisms that can participate in bacterial competition and in bacterial pathogenicity. UPEC UMN026 carries three genes, namely, ECUMN_0231, ECUMN_0232, and ECUMN_0233, which encode three uncharacterized proteins related to the T6SS that are conserved in strains from phylogroups B2 and D and have been proposed as biomarkers of UTIs. Aim: To analyze the frequency of the ECUMN_0231, ECUMN_0232, ECUMN_0233, and vgrG genes in UTI isolates, as well as their expression in Luria Bertani (LB) medium and urine; to determine whether these genes are related to UTI symptoms or bacterial competence and to identify functional domains on the putative proteins. Methods: The frequency of the ECUMN and vgrG genes in 99 clinical isolates from UPEC was determined by endpoint PCR. The relationship between gene presence and UTI symptomatology was determined using the chi2 test, with p < 0.05 considered to indicate statistical significance. The expression of the three ECUMN genes and vgrG was analyzed by RT-PCR. The antibacterial activity of strain UMN026 was determined by bacterial competence assays. The identification of functional domains and the docking were performed using bioinformatic tools. Results: The ECUMN genes are conserved in 33.3% of clinical isolates from patients with symptomatic and asymptomatic UTIs and have no relationship with UTI symptomatology. Of the ECUMN+ isolates, only five (15.15%, 5/33) had the three ECUMN and vgrG genes. These genes were expressed in LB broth and urine in UPEC UMN026 but not in all the clinical isolates. Strain UMN026 had antibacterial activity against UPEC clinical isolate 4014 (ECUMN−) and E. faecalis but not against isolate 4012 (ECUMN+). Bioinformatics analysis suggested that the ECUMN genes encode a chaperone/effector/immunity system. Conclusions: The ECUMN genes are conserved in clinical isolates from symptomatic and asymptomatic patients and are not related to UTI symptoms. However, these genes encode a putative chaperone/effector/immunity system that seems to be involved in the antibacterial activity of strain UMN026. [ABSTRACT FROM AUTHOR]

Context Hepatic steatosis is associated with decreased bone mineral density (BMD). Bone marrow fat fraction (BMFF) could play a role in this relationship in children with obesity. Objective The objectives of this work were (i) to examine the relationship between the lumbar spine (LS) BMFF and BMD, and (ii) to explore the mediating role of LS-BMFF on the relationship between percentage hepatic fat with LS-BMD in preadolescent children with overweight/obesity. Methods Hepatic fat and LS-BMFF (magnetic resonance imaging) and areal LS-BMD (LS-aBMD, dual-energy x-ray absorptiometry) were measured in 106 children (aged 10.6 ± 1.1 years, 53.8% girls) with overweight/obesity. Results LS-BMFF was inversely associated with LS-aBMD (r = −0.313; P =.001) and directly related with percentage hepatic fat (r = 0.276; P =.005). LS-BMFF was significantly greater in children with than without hepatic steatosis (P =.003; Cohen's d : 0.61; 95% CI, −0.21 to 1.0), while no significant difference was seen between children with overweight and those with obesity (P =.604; Cohen's d : 0.16; 95% CI, −0.21-0.55). Mediating analysis indicated that LS-BMFF is an important mediator (50%) in the association of hepatic fat with lower LS-aBMD (indirect effect: β = −.076; 95% CI, −0.143 to −0.015). Conclusion These findings suggest that hepatic steatosis, rather than overall excess adiposity, is associated with greater bone marrow adipose tissue in preadolescent children with overweight/obesity, which in turn, is related to lower BMD. Hepatic steatosis could be a potential biomarker of osteoporosis risk, and a therapeutic target for interventions that aim to reduce not only hepatic steatosis, but for those designed to improve bone health in such children. [ABSTRACT FROM AUTHOR]

Monitoring renal allograft function after transplantation is key for the early detection of allograft impairment, which in turn can contribute to preventing the loss of the allograft. Multiparametric renal MRI (mpMRI) is a promising noninvasive technique to assess and characterize renal physiopathology; however, few studies have employed mpMRI in renal allografts with stable function (maintained function over a long time period). The purposes of the current study were to evaluate the reproducibility of mpMRI in transplant patients and to characterize normal values of the measured parameters, and to estimate the labeling efficiency of Pseudo-Continuous Arterial Spin Labeling (PCASL) in the infrarenal aorta using numerical simulations considering experimental measurements of aortic blood flow profiles. The subjects were 20 transplant patients with stable kidney function, maintained over 1 year. The MRI protocol consisted of PCASL, intravoxel incoherent motion, and T1 inversion recovery. Phase contrast was used to measure aortic blood flow. Renal blood flow (RBF), diffusion coefficient (D), pseudo-diffusion coefficient (D*), flowing fraction (f), and T1 maps were calculated and mean values were measured in the cortex and medulla. The labeling efficiency of PCASL was estimated from simulation of Bloch equations. Reproducibility was assessed with the within-subject coefficient of variation, intraclass correlation coefficient, and Bland-Altman analysis. Correlations were evaluated using the Pearson correlation coefficient. The significance level was p less than 0.05. Cortical reproducibility was very good for T1, D, and RBF, moderate for f, and low for D*, while medullary reproducibility was good for T1 and D. Significant correlations in the cortex between RBF and f (r=0.66), RBF and eGFR (r=0.64), and D* and eGFR (r=-0.57) were found. Normal values of the measured parameters employing the mpMRI protocol in kidney transplant patients with stable function were characterized and the results showed good reproducibility of the techniques. [ABSTRACT FROM AUTHOR]

The visual content of the product area is crucial in an e-commerce site. This paper studies the differences in attention to product images in the product area in e-commerce sites considering the effects of purchase stage and product category. Attention to product images on websites is measured using eye-tracking in two experiments with 58 students and 66 subjects, with four product categories and four purchase tasks in each one. Our results show that pictures, in general, attract attention first, before the product names and price information. Furthermore, images attract less total attention than textual information. Images attract less attention when they are not crucial for completing the task, such as when purchasing a determined product or when locating product tracking information. Younger people (less than 30) spend much less time viewing the product pictures than older age groups (50 or more). According to our results, e-retailers could improve their sites' performance by adapting the products' presentation to the purchase tasks and visitor characteristics. [ABSTRACT FROM AUTHOR]

The complexity of corneal refraction modeling complicates geometrical analysis of gaze tracking systems. The task can be accomplished in different ways by means of different approximations. Depending on the assumptions made, errors can arise and the accuracy of trackers can end up determined to an excessive degree by the hardware setup and subject parameters. In this study, keeping the hardware and eye model the same, we compare different methods for evaluation of corneal refraction. Our results show that the approximated methods are sensitive to the calibration of the system and less robust to noise. The nonapproximated method removes any dependency on setup and allows clear differentiation between hardware and subject's calibration. Index Terms--Corneal refraction, gaze tracking.

The design of robust and high-performance gaze-tracking systems is one of the most important objectives of the eye-tracking community. In general, a subject calibration procedure is needed to learn system parameters and be able to estimate the gaze direction accurately. In this paper, we attempt to determine if subject calibration can be eliminated. A geometric analysis of a gaze-tracking system is conducted to determine user calibration requirements. The eye model used considers the offset between optical and visual axes, the refraction of the cornea, and Donder's law. This paper demonstrates the minimal number of cameras, light sources, and user calibration points needed to solve for gaze estimation. The underlying geometric model is based on glint positions and pupil ellipse in the image, and the minimal hardware needed for this model is one camera and multiple light-emitting diodes. This paper proves that subject calibration is compulsory for correct gaze estimation and proposes a model based on a single point for subject calibration. The experiments carried out show that, although two glints and one calibration point are sufficient to perform gaze estimation (error ~1[degrees]), using more light sources and calibration points can result in lower average errors. Index Terms--Calibration, gaze estimation, line of sight (LOS), point of regard (POR), video oculography.

Objectives: To examine the relationship between physical fitness and physical activity (PA) with specific abdominal fat depots and their potential implications for cardiometabolic risk and insulin resistance (IR) in children with overweight/obesity. Materials and Methods: A total of 116 children with overweight/obesity (10.7 ± 1.1 year, 54% girls) participated in the study. Abdominal visceral (VAT), subcutaneous (ASAT), and intermuscular abdominal adipose tissue (IMAAT) were assessed by magnetic resonance imaging. The cardiometabolic risk (MetS) score and the insulin resistance homeostasis model assessment (HOMA‐IR) were calculated. Health‐related physical fitness components (treadmill test, and 20 m shuttle run, handgrip, standing broad jump and 4 × 10 m tests) were evaluated, and PA was measured (accelerometry). Children were categorized as fit or unfit for each specific fitness test, and as active or inactive. Results: Higher VAT, ASAT, and IMAAT were associated with higher MetS score and HOMA‐IR (all p < 0.02). A better performance in all fitness tests and total and vigorous PA were strongly associated with lower VAT (all p < 0.04), ASAT (all p < 0.005), and IMAAT (all p < 0.005). Fit or active children had lower VAT, ASAT, and IMAAT (all p < 0.03) than their unfit or inactive counterparts. Conclusion: These results reinforce the importance of having adequate fitness and PA levels to reduce abdominal fat accumulation in children. Given that VAT, ASAT, and IMAAT are associated with higher risk of developing cardiovascular diseases and type 2 diabetes, the improvement of physical fitness by the promotion of PA should be goals of lifestyle interventions for improving health in children with overweight/obesity. [ABSTRACT FROM AUTHOR]