Impact of sociodemographic and economic determinants of health on COVID-19 infection: incidence variation between reference periods.

OBJECTIVES: The COVID-19 pandemic hit Portugal in March 2020, causing widespread disruption to various aspects of society. While extensive research has been conducted on the significance of socio-economic disparities in infection risk, this study aims to enhance our understanding of their evolving relationship over time by analysing four distinct periods in 2020. STUDY DESIGN AND METHODS: This retrospective observational ecological study included individuals residing in the Primary Healthcare Cluster areas of Almada-Seixal and Western Lisbon and Oeiras, who tested positive for SARS-CoV-2 through a polymerase chain reaction (PCR) test between the 2nd of March and the 8th of November of 2020. Using incidence rates for each specific neighbourhood (n = 29) and period, we explored the relationship between neighbourhood-level socio-economic variables and the risk of infection using negative-binomial regression models. RESULTS: In the analysed period, a total of 8562 confirmed COVID-19 cases were identified. Overall incidence rates for each period were sequentially 2.74, 5.03, 3.99 and 14.29 COVID-19 cases per 100,000 person-days. Housing overcrowding, illiteracy rate and place of birth were associated with increased risk of infection, while age, congregate living, and employment in the secondary sector exhibited the opposite association. No association was consistent across all time periods. CONCLUSIONS: Our findings support the idea that the influence of socio-economic determinants of health is not immutable throughout time. In a pandemic context where information, knowledge, beliefs, and behaviours are ever-changing and evolving, a dynamic, inclusive, and adaptable approach to disease control can lead to a more equitable distribution of improved outcomes, benefiting all strata of society.

Diphenylhexatriene membrane probes DPH and TMA-DPH: A comparative molecular dynamics simulation study.

Fluorescence spectroscopy and microscopy have been utilized as tools in membrane biophysics for decades now. Because phospholipids are non-fluorescent, the use of extrinsic membrane probes in this context is commonplace. Among the latter, 1,6-diphenylhexatriene (DPH) and its trimethylammonium derivative (TMA-DPH) have been extensively used. It is widely believed that, owing to its additional charged group, TMA-DPH is anchored at the lipid/water interface and reports on a bilayer region that is distinct from that of the hydrophobic DPH. In this study, we employ atomistic MD simulations to characterize the behavior of DPH and TMA-DPH in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and POPC/cholesterol (4:1) bilayers. We show that although the dynamics of TMA-DPH in these membranes is noticeably more hindered than that of DPH, the location of the average fluorophore of TMA-DPH is only ~3-4Å more shallow than that of DPH. The hindrance observed in the translational and rotational motions of TMA-DPH compared to DPH is mainly not due to significant differences in depth, but to the favorable electrostatic interactions of the former with electronegative lipid atoms instead. By revealing detailed insights on the behavior of these two probes, our results are useful both in the interpretation of past work and in the planning of future experiments using them as membrane reporters.

Fluorescence of nitrobenzoxadiazole (NBD)-labeled lipids in model membranes is connected not to lipid mobility but to probe location.

Nitrobenzoxadiazole (NBD)-labeled lipids are popular fluorescent membrane probes. However, the understanding of important aspects of the photophysics of NBD remains incomplete, including the observed shift in the emission spectrum of NBD-lipids to longer wavelengths following excitation at the red edge of the absorption spectrum (red-edge excitation shift or REES). REES of NBD-lipids in membrane environments has been previously interpreted as reflecting restricted mobility of solvent surrounding the fluorophore. However, this requires a large change in the dipole moment (Δµ) of NBD upon excitation. Previous calculations of the value of Δµ of NBD in the literature have been carried out using outdated semi-empirical methods, leading to conflicting values. Using up-to-date density functional theory methods, we recalculated the value of Δµ and verified that it is rather small (∼2 D). Fluorescence measurements confirmed that the value of REES is ∼16 nm for 1,2-dioleoyl-sn-glycero-3-phospho-l-serine-N-(NBD) (NBD-PS) in dioleoylphosphatidylcholine vesicles. However, the observed shift is independent of both the temperature and the presence of cholesterol and is therefore insensitive to the mobility and hydration of the membrane. Moreover, red-edge excitation leads to an increased contribution of the decay component with a shorter lifetime, whereas time-resolved emission spectra of NBD-PS displayed an atypical blue shift following excitation. This excludes restrictions to solvent relaxation as the cause of the measured REES and TRES of NBD, pointing instead to the heterogeneous transverse location of probes as the origin of these effects. The latter hypothesis was confirmed by molecular dynamics simulations, from which the calculated heterogeneity of the hydration and location of NBD correlated with the measured fluorescence lifetimes/REES. Globally, our combination of theoretical and experiment-based techniques has led to a considerably improved understanding of the photophysics of NBD and a reinterpretation of its REES in particular.

Influence of the sterol aliphatic side chain on membrane properties: a molecular dynamics study.

Following a recent experimental investigation of the effect of the length of the alkyl side chain in a series of cholesterol analogues (Angew. Chem., Int. Ed., 2013, 52, 12848-12851), we report here an atomistic molecular dynamics characterization of the behaviour of methyl-branched side chain sterols (iso series) in POPC bilayers. The studied sterols included androstenol (i-C0-sterol) and cholesterol (i-C8-sterol), as well as four other derivatives (i-C5, i-C10, i-C12 and i-C14-sterol). For each sterol, both subtle local effects and more substantial differential alterations of membrane properties along the iso series were investigated. The location and orientation of the tetracyclic ring system is almost identical in all compounds. Among all the studied sterols, cholesterol is the sterol that presents the best matching with the hydrophobic length of POPC acyl chains, whereas longer-chained sterols interdigitate into the opposing membrane leaflet. In accordance with the experimental observations, a maximal ordering effect is observed for intermediate sterol chain length (i-C5, cholesterol, i-C10). Only for these sterols a preferential interaction with the saturated sn-1 chain of POPC (compared to the unsaturated sn-2 chain) was observed, but not for either shorter or longer-chained derivatives. This work highlights the importance of the sterol alkyl chain in the modulation of membrane properties and lateral organization in biological membranes.

Behaviour of NBD-head group labelled phosphatidylethanolamines in POPC bilayers: a molecular dynamics study.

A complete homologous series of fluorescent phosphatidylethanolamines (diCnPE), labelled at the head group with a 7-nitrobenz-2-oxa-1,3-diazo-4-yl(NBD) fluorophore and inserted in 1-palmitoyl, 2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayers, was studied using atomistic molecular dynamics simulations. The longer-chained derivatives of NBD-diCnPE, with n = 14, 16, and 18, are commercially available, and widely used as fluorescent membrane probes. Properties such as location of atomic groups and acyl chain order parameters of both POPC and NBD-diCnPE, fluorophore orientation and hydrogen bonding, membrane electrostatic potential and lateral diffusion were calculated for all derivatives in the series. Most of these probes induce local disordering of POPC acyl chains, which is on the whole counterbalanced by ordering resulting from binding of sodium ions to lipid carbonyl/glycerol oxygen atoms. An exception is found for NBD-diC16PE, which displays optimal matching with POPC acyl chain length and induces a slight local ordering of phospholipid acyl chains. Compared to previously studied fatty amines, acyl chain-labelled phosphatidylcholines, and sterols bearing the same fluorescent tag, the chromophore in NBD-diCnPE locates in a similar region of the membrane (near the glycerol backbone/carbonyl region) but adopts a different orientation (with the NO2 group facing the interior of the bilayer). This modification leads to an inverted orientation of the P-N axis in the labelled lipid, which affects the interface properties, such as the membrane electrostatic potential and hydrogen bonding to lipid head group atoms. The implications of this study for the interpretation of the photophysical properties of NBD-diCnPE (complex fluorescence emission kinetics, differences with other NBD lipid probes) are discussed.

Pneumocystis jirovecii pneumonia with an atypical granulomatous response after kidney transplantation.

Pneumocystis jirovecii pneumonia (PCP) continues to be a leading cause of morbidity and mortality in kidney transplant recipients. Granulomatous PCP is an unusual histological presentation that has been described in a variety of immunosuppressive conditions. Previous studies have demonstrated an association between granulomatous disorders and hypercalcemia, the purported mechanism of which is extrarenal production of 1,25-dihydroxyvitamin D by activated macrophages. Here, we report a case of granulomatous formation in a kidney transplant recipient with PCP who presented with hypercalcemia and suppressed parathyroid hormone, both of which resolved after successful treatment of the pneumonia. In immunocompromised patients, pulmonary infection associated with hypercalcemia should raise the suspicion of PCP and other granulomatous disorders.

Research Note: The influence of different isoleucine: lysine ratios on the growth performance of broiler chickens fed low-protein diets.

Two trials were carried out to assess the effects of different ratios of standardized ileal digestible isoleucine:lysine (SID Ile:Lys) on the growth performance of broiler chickens fed low-protein diets. A total of 1,320 male chickens were distributed in each trial into 6 treatments, with 10 replicates with 22 birds each. A control diet was formulated that satisfied the nutritional requirements of the broilers, and a low-protein diet was formulated with reduced protein content, meeting broiler nutritional requirements, except for the SID Ile levels. Five SID Ile:Lys ratios (56%, 61%, 66%, 71%, and 76%) were obtained by adding l-isoleucine to the low-protein diet. The body weight (BW), body weight gain (BWG), average daily feed intake (ADFI), and feed conversion ratio (FCR) were evaluated from day 1 to day 21 in trial 1, and from day 22 to day 44 in trial 2. ANOVA was performed on the data, and the treatments were compared to the control group using Dunnett's test (P ≤ 0.05). Regression analyses were performed for modeling the variables assessed and the ratios of SID Ile:Lys. There was no significant difference between the treatments on ADFI of birds (P > 0.05). The BW, BWG, and FCR showed a quadratic effect as the SID Ile:Lys ratio increased in low-protein diets in trials 1 and 2 (P ≤ 0.05). In conclusion, the recommended ratio of SID Ile:Lys in low-protein diets for growth performance is around 66% for broiler chickens from 1 to 21 d old and is around 65% for broiler chickens from 22 to 44 d old.

Switchable nonlinear optical properties of η5-monocyclopentadienylmetal complexes: a DFT approach.

Density functional theory (DFT) calculations have been carried out to investigate the switching of the second-order nonlinear optical (NLO) properties of η(5)-monocyclopentadienyliron(II) and ruthenium(II) model complexes presenting 5-(3-(thiophen-2-yl)benzo[c]thiophen-1-yl)thiophene-2-carbonitrile as a ligand. The switching properties were induced by redox means. Both oxidation and reduction stimulus have been considered, and calculations have been performed both for the complexes and for the free benzo[c]thiophene derivative ligand in order to elucidate the role played by the organometallic fragment on the second-order NLO properties of these complexes. B3LYP, CAM-B3LYP, and M06 functionals were used for our calculations. The results show some important structural changes upon oxidation/reduction that are accompanied by significant differences on the corresponding second-order NLO properties. TD-DFT calculations show that these differences on the second-order NLO response upon oxidation/reduction are due to a change in the charge transfer pattern, in which the organometallic iron and ruthenium moieties play an important role. The calculated static hyperpolarizabilities were found to be strongly functional dependent. CAM-B3LYP, however, seems to predict more reliable structural and optical data as well as hyperpolarizabilities when compared to experimental data. The use of this functional predicts that the studied complexes can be viewed as acting as redox second-order NLO switches, in particular using oxidation stimulus. The ß(tot) value of one-electron oxidized species is at least ~8.3 times (for Ru complex) and ~5.5 times (for Fe complex) as large as that of its nonoxidized counterparts.

T1 signal intensity in the dentate nucleus after the administration of the macrocyclic gadolinium-based contrast agent gadoterate meglumine: An observational study.

INTRODUCTION AND AIMS: Contradictory results have been reported about hyperintensity of the globus pallidus and/or dentate nucleus on unenhanced T1-weighted magnetic resonance (MR) images after exposure to various gadolinium-based contrast agents. This change in signal intensity varies with different gadolinium-based contrast agents. We aimed to determine whether signal intensity in the dentate nucleus is increased in unenhanced T1-weighted images in patients who have undergone multiple studies with the macrocyclic gadolinium-based contrast agent gadoterate meglumine. We thoroughly reviewed the literature to corroborate our results. MATERIALS AND METHODS: We included patients who had undergone more than 10 MR studies with gadoterate meglumine. We quantitatively analyzed the signal intensity in unenhanced T1-weighted MR images measured in regions of interest placed in the dentate nucleus and the pons, and we calculated the dentate nucleus-to-pons signal intensity ratios and the differences between the ratio in the first MR study and the last MR study. We used t-tests to evaluate whether the differences between the signal intensity ratios were different from 0. We also analyzed the subgroups of patients who had been administered <15 and ≥15 doses of gadoterate meglumine. We used Pearson correlation to determine the relationships between the differences in the signal intensity ratios and the number of doses of gadoterate meglumine administered. RESULTS: The 54 patients (26 men) had received a mean of 13.8±3.47 doses (range, 10-23 doses). The difference in the dentate nucleus-pons signal intensity ratio between the first and last MR study was -0.0275±0.1917 (not significantly different from 0; p=0.2968) in the entire group, -0.0357±0.2204 (not significantly different from 0; p = 0.351 in the patients who had received <15 doses (n=34), and -0.0135±0.1332 (not significantly different from 0; p = 0.655) in those who had received ≥15 doses (n=20). Differences in signal intensity ratios did not correlate significantly with the accumulated dose of gadoterate meglumine (P = 0.9064; ρ = -0.0164 [95%]). CONCLUSIONS: Receiving more than 10 doses of gadoterate meglumine was not associated with increased signal intensity in the dentate nucleus.

The effects of arginine supplementation through different ratios of arginine:lysine on performance, skin quality and creatine levels of broiler chickens fed diets reduced in protein content.

Two trials were carried out to assess the effects of arginine supplementation through ratios of digestible arginine:lysine on growth performance, skin quality and creatine levels in muscle and serum of broiler chickens fed diets reduced in protein content. A total of 1,540 Cobb500 male chickens were distributed into 7 treatments, with 10 replicates with 22 birds each. The experimental diets were based on corn and soybean meal, and a control diet was formulated to satisfy broiler nutritional requirements. A basal diet with reduced protein content was formulated to meet broiler nutritional requirements, except for SID Arg levels. The experimental diets were obtained by adding L-arginine to basal diets, meeting 6 different SID Arg:Lys ratios (94, 100, 106, 112, 118, and 124%). Body weight, body weight gain, average daily feed intake, and feed conversion ratio were evaluated from 01 to 21 d old (trial 1) and from 22 to 44 d old (trial 2). At 21 and 44 d, in trials 1 and 2, respectively, birds were slaughtered to assess skin thickness (ST), skin strength (SS), creatine level in muscle (CRM) and serum (CRS). Data were subjected to ANOVA, and treatments were compared to the control group by Dunnett's test (P ≤ 0.05). Regression analyses were performed to model the variables assessed and the ratios of SID Arg:Lys. The SID Arg:Lys ratios did not affect ADFI of broilers in both trials (P > 0.05), whereas it linearly increased the BW, BWG, and ST, in both trials (P < 0.001). The FCR of broilers linearly decreased, in trial 1 (P = 0.038) and trial 2 (P < 0.001). The CRM of birds had a linear effect (P < 0.001) in trial 1, and a quadratic effect (P = 0.001) in trial 2. The CRS and SS of broilers linearly increased, in trial 2 (P < 0.001). In conclusion, increasing SID Arg:Lys ratios in diets reduced CP enhanced growth performance, skin quality and CR levels in muscle and serum of broiler chickens from 01 to 21 and 22 to 44 d old.

Structure and phase transformations of DPPC lipid bilayers in the presence of nanoparticles: insights from coarse-grained molecular dynamics simulations.

In this article, we investigate fluid-gel transformations of a DPPC lipid bilayer in the presence of nanoparticles, using coarse-grained molecular dynamics. Two types of nanoparticles are considered, specifically a 3 nm hydrophobic nanoparticle located in the core of the bilayer and a 6 nm charged nanoparticle located at the interface between the bilayer and water phase. Both negatively and positively charged nanoparticles at the bilayer interface are investigated. We demonstrate that the presence of all types of nanoparticles induces disorder effects in the structure of the lipid bilayer. These effects are characterized using computer visualization of the gel phase in the presence of nanoparticles, radial distribution functions, and order parameters. The 3 nm hydrophobic nanoparticle immersed in the bilayer core and the positively charged nanoparticle at the bilayer surface have no effect on the temperature of the fluid-gel transformation, compared to the bulk case. Interestingly, a negatively charged hydrophobic nanoparticle located at the surface of the bilayer causes slight shift of the fluid-gel transformation to a lower temperature, compared to the bulk bilayer case.

Evaluation of phosphinoamidoester-derived Pd catalysts in the asymmetric allylic alkylation reaction: theoretical studies and mechanistic insights.

Two simple hemilabile P,O-coordinating phosphinoamidoester ligands 6a and 6b were synthesized and studied in the Pd(0)-catalyzed asymmetric allylic alkylation of rac-1,3-diphenylpropenyl acetate affording a highest ee of 83% ee with 6a. To gain an insight into the actual mechanism of this catalytic reactions, which had previously been investigated with a first generation family of P,O-coordinating phosphinoamido-alcohol ligands-4a and 4b-a semiempirical computational study was carried out with the Pd-allyl complexes formed from both 4a and 6a including Hitchcock's phosphinoamido-alcohol ligand 5 (R(1)= H, R(2)= Ph). The results of this study substantiate a working model that has previously been proposed for this reaction using hemilabile P,O-coordinating phosphinoamido-type ligands.

Recent developments in molecular dynamics simulations of fluorescent membrane probes.

Due to their sensitivity and versatility, the use of fluorescence techniques in membrane biophysics is widespread. Because membrane lipids are non-fluorescent, extrinsic membrane probes are widely used. However, the behaviour of these probes when inserted in the bilayer is often poorly understood, and it can be hard to distinguish between legitimate membrane properties and perturbation resulting from probe incorporation. Atomistic molecular dynamics simulations present a convenient way to address these issues and have been increasingly used in recent years in this context. This article reviews the application of molecular dynamics to the study of fluorescent membrane probes, focusing on recent work with complex design fluorophores and ordered bilayer systems.

T1 signal intensity in the dentate nucleus after the administration of the macrocyclic gadolinium-based contrast agent gadoterate meglumine: an observational study. / Intensidad de la señal en T1 en el núcleo dentado tras la administración del agente de contraste con gadolinio macrocíclico gadoterato de meglumina: un estudio observacional.

INTRODUCTION AND AIMS: Contradictory results have been reported about hyperintensity of the globus pallidus and/or dentate nucleus on unenhanced T1-weighted magnetic resonance (MR) images after exposure to various gadolinium-based contrast agents. This change in signal intensity varies with different gadolinium-based contrast agents. We aimed to determine whether signal intensity in the dentate nucleus is increased in unenhanced T1-weighted images in patients who have undergone multiple studies with the macrocyclic gadolinium-based contrast agent gadoterate meglumine. We thoroughly reviewed the literature to corroborate our results. MATERIALS AND METHODS: We included patients who had undergone more than 10 MR studies with gadoterate meglumine. We quantitatively analyzed the signal intensity in unenhanced T1-weighted MR images measured in regions of interest placed in the dentate nucleus and the pons, and we calculated the dentate nucleus-to-pons signal intensity ratios and the differences between the ratio in the first MR study and the last MR study. We used t-tests to evaluate whether the differences between the signal intensity ratios were different from 0. We also analyzed the subgroups of patients who had been administered<15 and ≥15 doses of gadoterate meglumine. We used Pearson correlation to determine the relationships between the differences in the signal intensity ratios and the number of doses of gadoterate meglumine administered. RESULTS: The 54 patients (26 men) had received a mean of 13.8±3.47 doses (range, 10-23 doses). The difference in the dentate nucleus-pons signal intensity ratio between the first and last MR study was -0.0275±0.1917 (not significantly different from 0; p=0.2968) in the entire group, -0.0357±0.2204 (not significantly different from 0; p=0.351 in the patients who had received <15 doses (n=34), and -0.0135±0.1332 (not significantly different from 0; p=0.655) in those who had received ≥15 doses (n=20). Differences in signal intensity ratios did not correlate significantly with the accumulated dose of gadoterate meglumine (P=0.9064; ρ=-0.0164 [95%]). CONCLUSIONS: Receiving more than 10 doses of gadoterate meglumine was not associated with increased signal intensity in the dentate nucleus.

Effects of fluorescent probe NBD-PC on the structure, dynamics and phase transition of DPPC. A molecular dynamics and differential scanning calorimetry study.

We present a combined theoretical (molecular dynamics, MD) and experimental (differential scanning calorimetry, DSC) study of the effect of 7-nitrobenz-2-oxa-1,3-diazol-4-yl (NBD) acyl chain-labeled fluorescent phospholipid analogs (C6-NBD-PC and C12-NBD-PC) on 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayers. DSC measurements reveal that <1 mol% of NBD-PC causes elimination of the pre-transition and a large loss of cooperativity of the main transition of DPPC. Labeling with C6-NBD-PC or C12-NBD-PC shifts the main transition temperature to lower or higher values, respectively. Following our recent report on the location and dynamics of these probes (BBA 1768 (2007) 467-478) in fluid phase DPPC, we present a detailed analysis of 100-ns MD simulations of systems containing either C6-NBD-PC or C12-NBD-PC, focused on their influence on several properties of the host bilayer. Whereas most monitored parameters are not severely affected for 1.6 mol% of probe, for the higher concentration studied (6.2 mol%) important differences are evident. In agreement with published reports, we observed that the average area per phospholipid molecule increases, whereas DPPC acyl chain order parameters decrease. Moreover, we predict that incorporation of NBD-PC should increase the electrostatic potential across the bilayer and, especially for C12-NBD-PC, slow lateral diffusion of DPPC molecules and rotational mobility of DPPC acyl chains.

Calcitriol and FGF-23, but neither PTH nor sclerostin, are associated with calciuria in CKD.

PURPOSE: The recent observation that urinary calcium excretion (UCE) drops considerably with CKD and that this effect may occur beyond compensation for reduced intestinal calcium absorption suggests that CKD per se is a state of sustained positive calcium balance, a mechanism likely to contribute to vascular calcification and CVD in CKD. However, the determinants of UCE reduction in CKD are not well understood and there is a lack of clinical studies, particularly in the CKD population. Therefore, in this study, we aimed to evaluate variables associated with UCE in a CKD cohort. METHODS: Baseline data on 356 participants of the Progredir Study, Sao Paulo, Brazil, essentially composed of CKD G3a-G4, were analyzed according to UCE (24 h urine collection). RESULTS: Median 24 h UCE was 38 mg/day (IQR 21-68 mg/day) and 0.48 mg/kg/day (IQR 0.28-0.82 mg/kg/day). In univariate analysis, UCE was inversely related to age, phosphorus, 1-84 PTH, FGF-23 and sclerostin, and positively associated with eGFR, DBP, 1,25(OH)2-vitamin D, calcium, bicarbonate, total calorie intake and spironolactone use. After adjustments for age, sex and eGFR, only 1,25(OH)2-vitamin D, calcium, FGF-23, bicarbonate and total calorie intake remained associated with it, but not PTH nor sclerostin. Lastly, in a multivariable model, eGFR, serum 1,25(OH)2-vitamin D, calcium, and FGF-23 remained associated with UCE. Similar results were observed when calcium fractional excretion was used instead of UCE, with eGFR, 1-25-vitamin D and FGF-23 remaining as independent associations. CONCLUSION: Our results showed that CKD is associated with very low levels of UCE and that 1,25(OH)2-vitamin D, serum calcium and FGF-23 were independently associated with UCE in this population, raising the question whether these factors are modulators of the tubular handling of calcium in CKD.

Location and dynamics of acyl chain NBD-labeled phosphatidylcholine (NBD-PC) in DPPC bilayers. A molecular dynamics and time-resolved fluorescence anisotropy study.

100-ns molecular dynamics simulations of fluid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayers, both pure and containing 7-nitrobenz-2-oxa-1,3-diazol-4-yl (NBD) acyl-chain labeled fluorescent analogs (C6-NBD-PC and C12-NBD-PC), are described. These molecules are widely used as probes for lipid structure and dynamics. The results obtained here for pure DPPC agree with both experimental and theoretical published works. We verified that the NBD fluorophore of both derivatives loops to a transverse location closer to the interface than to the center of the bilayer. Whereas this was observed previously in experimental literature works, conflicting transverse locations were proposed for the NBD group. According to our results, the maximum of the transverse distribution of NBD is located around the glycerol backbone/carbonyl region, and the nitro group is the most external part of the fluorophore. Hydrogen bonds from the NH group of NBD (mostly to glycerol backbone lipid O atoms) and to the nitro O atoms of NBD (from water OH groups) are continuously observed. Rotation of NBD occurs with approximately 2.5-5 ns average correlation time for these probes, but very fast, unresolved reorientation motions occur in <20 ps, in agreement with time-resolved fluorescence anisotropy measurements. Finally, within the uncertainty of the analysis, both probes show lateral diffusion dynamics identical to DPPC.

The trabecular bone score: Relationships with trabecular and cortical microarchitecture measured by HR-pQCT and histomorphometry in patients with chronic kidney disease.

The trabecular bone score (TBS) is a novel tool using grayscale variograms of the lumbar spine bone mineral density (BMD) to assess trabecular bone microarchitecture. Studies in patients with chronic kidney disease (CKD) suggest it may be helpful in assessing fracture risk. However, TBS has not been validated as a measure of trabecular architecture against transiliac bone biopsy with histomorphometry in CKD patients. We hypothesized that TBS would reflect trabecular architecture at the iliac crest in CKD patients. We obtained tetracycline double labeled transiliac crest bone biopsy, areal BMD of the spine, total hip, femoral neck (FN) and spine TBS by dual energy X-ray absorptiometry (DXA), and cortical and trabecular volumetric density and microarchitecture by high resolution peripheral quantitative computed tomography (HR-pQCT) in CKD patients from two centers: twenty-two patients from Columbia University Medical Center, USA and thirty patients from Hospital das Clinicas - Universidade de São Paulo, Brazil. Two patients were excluded for outlier status. Univariate and multivariate relationships between TBS and measures from DXA, HR-pQCT and histomorphometry were determined. Patients were 50.2 ±â€¯15.8 years old, 23 (46%) were men, and 33 (66%) were on dialysis. TBS was <1.31 in 21 (42%) patients and 22%, 14% and 10% had T-scores ≤ -2.5 at spine, FN and total hip respectively. In univariate regression, TBS was significantly associated with trabecular bone volume (BV/TV), trabecular width (Tb.Wi), trabecular spacing, cortical width but not with trabecular number or cortical porosity. FN Z-score and height were also associated with cancellous BV/TV and Tb.Wi, In multivariate analysis, TBS remained an independent predictor of BV/TV and Tb.Wi. There were no relationships between TBS and dynamic parameters from histomorphometry. These data suggest that TBS reflected trabecular microarchitecture and cortical width measured by bone biopsy in CKD patients. Future studies should address its utility in the identification of CKD patients who may benefit from fracture prevention strategies.

Excess thermodynamics of mixtures involving xenon and light linear alkanes by computer simulation.

Excess molar enthalpies and excess molar volumes as a function of composition for liquid mixtures of xenon + ethane (at 161.40 K), xenon + propane (at 161.40 K) and xenon + n-butane (at 182.34 K) have been obtained by Monte Carlo computer simulations and compared with available experimental data. Simulation conditions were chosen to closely match those of the corresponding experimental results. The TraPPE-UA force field was selected among other force fields to model all the alkanes studied, whereas the one-center Lennard-Jones potential from Bohn et al. was used for xenon. The calculated H(m)(E) and V(m)(E) for all systems are negative, increasing in magnitude as the alkane chain length increases. The results for these systems were compared with experimental data and with other theoretical calculations using the SAFT approach. An excellent agreement between simulation and experimental results was found for xenon + ethane system, whereas for the remaining two systems, some deviations that become progressively more significant as the alkane chain length increases were observed.

Mechanisms of removal of three widespread pharmaceuticals by two clay materials.

Pharmaceutical residues presence in the environment is among nowadays top emergent environmental issues. For removal of such pollutants, adsorption is a generally efficient process that can be complementary to conventional treatment. Research of cheap, widely available adsorbents may make this process economically attractive. The aim of the present work was to evaluate the capacity of two clay materials (exfoliated vermiculite, LECA) to adsorb gemfibrozil, mefenamic acid and naproxen in lab-scale batch assays. Results show that both adsorbents are able to remove the pharmaceuticals from aqueous medium. Although vermiculite exhibited higher adsorption capacities per unit mass of adsorbent, LECA yielded higher absolute removals of the pharmaceuticals due to the larger mass of adsorbent. Quantum chemistry calculations predicted that the forms of binding of the three molecules to the vermiculite surface are essentially identical, but the adsorption isotherm of naproxen differs substantially from the other two's. The linear forms of the latter impose limits at lower concentrations to the removal efficiencies of these pharmaceuticals by vermiculite, thereby electing LECA as more efficient. Notwithstanding, vermiculite's high specific adsorption capacity and also its much faster adsorption kinetics suggest that there may be some benefits in combining both materials as a composite adsorbent solution.