HR-pQCT detects alterations in bone microstructure in men with CKD stages 3 and 4, which are influenced by hormonal changes and body composition
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INTRODUCTION: Factors associated with osteodystrophy in predialysis patients are poorly understood. In the present study, we attempted to evaluate the impact of body composition and hormonal regulatory factors on the bone microstructure in a group of men with chronic kidney disease (CKD) stages 3 and 4. MATERIALS AND METHODS: 46 men, aged 50 - 75 years, with previously unrecognized CKD were evaluated by high-resolution peripheral quantitative computed tomography (HR-pQCT), and dual-energy X-ray absorptiometry (DXA). HR-pQCT parameters were correlated with estimated glomerular filtration rate (eGFR), age, body mass index (BMI), muscle mass index (MMI), and biochemistry. RESULTS: As compared to patients in stage 3 CKD, those with stage 4 CKD showed lower serum 25-hydroxyvitamin D (25(OH)D) and bicarbonate levels, and higher serum fibroblast growth factor 23 (FGF-23) and parathyroid hormone (PTH) levels. They also exhibited lower total, trabecular, and cortical volumetric bone mineral density, lower trabecular bone volume/tissue volume, trabecular number, trabecular and cortical thickness, and increased heterogeneity of the trabecular network. In the whole cohort, cortical bone density and thickness were negatively associated with age, PTH, and FGF-23, and positively with BMI. Trabecular bone parameters were positively associated with MMI and 25(OH)D. After simultaneously adjusting for age and eGFR, BMI, and MMI remained significantly associated with bone microstructural variables. CONCLUSION: HR-pQCT showed significant differences in bone microstructure in stage 4 vs. stage 3 CKD patients. Increased BMI, probably due to increased muscle mass, may favorably affect bone architecture in predialysis CKD patients.
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Development of a non-invasive method for monitoring variations in salt concentrations of seawater using nuclear technique and Monte Carlo simulation.

In the oil production industry, water is used as a fluid injected into the well to raise the oil when the well is depressurized. Water thus produced presents variations in the concentrations of dissolved salts, as there is a mixture of different types of water, related to its origin (such as connate water, sea water). Because it is reused in oil production, water needs to be monitored to maintain the standard suitable for its use as it can be hypersaline, contributing to the encrustation of pipes and contamination of underground water reservoirs. In this study, a noninvasive method was developed to determine the salt concentration in seawater. The method uses a detection system that contains a NaI(Tl) detector, a241Am source, and a sample holder to measure the mass attenuation coefficient of saltwater samples. For validation, the same setup was also simulated using the MCNPX code. Saltwater samples with different concentrations of NaCl and KBr were used as a proxy for seawater. The mass attenuation coefficients for the simulation exhibited the smallest relative errors (up to 6.2%), and the experimental ones exhibited the highest relative errors (up to 25%) when compared with theoretical values.

Monitoring of bacterial community structure and growth: An alternative tool for biofilm microanalysis.

Microorganisms, such as bacteria, tend to aggregate and grow on surfaces, secreting extracellular polymeric substances (EPS), forming biofilms. Biofilm formation is a life strategy, because through it microorganisms can create their own microhabitats. Whether for remediation of pollutants or application in the biomedical field, several methodological approaches are necessary for a more accurate analysis of the role and potential use of bacterial biofilms. The use of computerized microtomography to monitor biofilm growth appears to be an advantageous tool due to its non-destructive character and its ability to render 2D and 3D visualization of the samples. In this study, we used several techniques such as analysis of microbiological parameters and biopolymer concentrations to corroborate porosity quantified by 2D and 3D imaging. Quantification of the porosity of samples by microtomography was verified by increased enzymatic activity and, consequently, higher EPS biopolymer synthesis to form biofilm, indicating growth of the biofilm over 96 â€‹h. Our interdisciplinary approach provides a better understanding of biofilm growth, enabling integrated use of these techniques as an important tool in bioremediation studies of environments impacted by pollutants.

Monitoring bioturbation by a small marine polychaete using microcomputed tomography.

Bioturbation is one of the principle biological processes involved in transporting particles and solutes within sediments, which contributes to the maintenance of biodiversity. In muddy polluted environments, bioturbation may increase pollutant flux at the water-sediment interface, thereby enhancing contaminant bioavailability. The behavior of organisms dictates bioturbation, and gallery shape influences the magnitude of solute transport. Thus, quantitative investigations of gallery shape are fundamental to understanding how pollutant and solute transport is enhanced by bioturbators in muddy sediments. However, there is a lack of tools for quantitatively analyzing gallery geometry, especially for assessing bioturbation and gallery properties through time. Despite the potential of microcomputed tomography (µCT) for quantitative analyses of bioturbation, few such studies have been carried out. Here, we aimed to investigate the potential of µCT for quantitatively assessing the shape and geometric properties of galleries made by small marine polychaetes and their evolution through time in muddy sediments. We focused on Laeonereis acuta (Treadwell, 1923) (Nereididae, Polychaeta), which is a key bioturbator in marine coastal ecosystems. Using 2D and 3D images generated from µCT, we evaluated L. acuta galleries and propose several indexes to quantitatively assess gallery evolution and the role of gallery parameters in bioturbation. Quantitative investigations of polychaete galleries using µCT can assist in monitoring how bioturbation influences sedimentary systems.