Small Solutes Research Articles

MO703URINE VOLUME AS A MARKER OF RESIDUAL KIDNEY FUNCTION IN PERITONEAL DIALYSIS PATIENTS: QUANTITATIVE ASSESSMENT

Abstract Background and Aims In dialysis patients, urine volume is an easy-to-obtain marker of residual kidney function but information is lacking of its potential value as an estimate of the renal contribution to total clearance of small solutes. We explored whether correlations of urine volume with different estimations of the residual renal function for urea, creatinine, and phosphorus, could be used to assess renal solute clearances and renal mass removal for investigated solutes. Method In an observational study of 94 non-anuric (urine output ≥ 100 mL per 24 hours) patients (54% men, median age 59 [45 - 68] year, BMI 25.8 [21.4 - 27.7] kg/m2) undergoing automated (n = 59) or continuous ambulatory (n = 35) peritoneal dialysis (PD), we evaluated renal, peritoneal and total (renal plus peritoneal) solute removal (g/week) and clearance (L/week) in relation to urine volume (L/day). Urine volume, renal clearances, ratio of urine solute to serum solute concentration, removed mass of each solute and the ratio of mass removed by urine (renal clearance) over total mass removed by urine and dialysate (total clearance) for urea, creatinine and phosphorus were estimated from 24 h collections of urine and dialysate and determination of solute concentrations in serum, urine and dialysate. Statistical dependence between variables was tested using Spearman’s correlation coefficient (rho). Data are expressed as median with interquartile range. Results Median 24-hour urine output was 560 [323 – 938] mL. Renal mass removal for urea, creatinine and phosphorus was 10.1 [4.5 – 17.1], 3.5 [1.8 – 5.6] and 1.0 [0.4 – 1.7] g/week, respectively. The average contribution of residual renal removal to the total mass removed was 28% [17% - 41%] for urea, 56% [30% - 72%] for creatinine and 44% [24% - 58%] for phosphorus. Serum creatinine correlated weakly and negatively with urine volume (rho = -0.26, p < 0.05), but no such relationship was observed for urea and phosphorus. Only urine concentration of creatinine correlated weakly with urine volume with rho = -0.28 and p < 0.01. Urine concentration over plasma concentration did not correlate with urine volume for any solute. Renal urea clearance (20.1 [11.4 - 35.7] L/week) correlated positively with creatinine renal clearance (43.0 [18.9 - 75.1] L/week), (rho = 0.92), and with phosphorus renal clearance (17.3 [7.6 - 32.9] L/week), (rho = 0.89, p < 0.001; Fig. 1A), while renal creatinine clearance correlated positively with phosphorus renal clearance (rho = 0.86, p<0.001). Urine volume correlated positively with urea, creatinine and phosphorus clearances at rho 0.78, 0.63 and 0.73, respectively (all p< 0.001), and with renal removal of mass of urea, creatinine, and phosphorus with rho= 0.83, 0.68 and 0.74 (Fig. 1B), respectively; all p<0.001. Conclusion In PD patients, solute renal clearances and renal mass removal for urea, creatinine and phosphorus may be predicted from urine volume. Among renal clearances for urea, creatinine, and phosphorus two of them may be assessed based on measurements of the third one.

Nature-Based Deployment Strategies for Multiple Paces of Change: The Case of Oimachi, Japan

In this article a planning approach is proposed to accommodate different paces of urbanisation. Instead of responding to a single problem with a Pavlov-type of response, analysis shows that the transformational tempi of different urban landscapes require multiple deployment strategies to develop urban environments that are sustainable and resilient. The application of nature-based solutions, enhancing both human and natural health in cities, is used as the foundation for the design of deployment strategies that respond to different paces of urban change. The results show that urban characteristics, such as population density and built space is, partly, dependent on the underlying landscape characteristics, therefore show specific development pathways. To create liveable and sustainable urban areas that can deal holistically with a range of intertwined problems, specific deployment strategies should be used in each specific urban context. This benefits the city-precinct as a whole and at the local scale. Even small nature-based solutions, applied as the right deployment strategy in the right context, have profound impact as the starting point of a far-reaching urban transformation. The case-study for Oimachi in Japan illustrates how this planning approach can be applied, how the different urban rhythms are identified, and to which results this leads.

Microtextures on quartz and zircon grain surfaces in the Barra del Tordo and Tesoro beaches, northwestern Gulf of Mexico

Surface features of quartz and zircon grains in the Barra del Tordo (PBT) and Tesoro (PT) beaches, NW Gulf of Mexico (GoM), were analyzed. The microtextures in the PBT and PT beaches were classified into mechanical, chemical, and mechanical/chemical origin. The quartz grains from the two beach areas were subrounded to rounded in shape. Rounded zircon grains in PT suggest that the sediments were derived by wind, long transport distance, and long residence time relative to PBT. Rounded quartz grains with the combination of bulbous and broken edges indicated a recycled provenance. Mechanical features such as V-shaped marks, impact scars, conchoidal fractures, and straight-curved grooves indicated a fluvial environment. Chemical features such as solution pits, crystal overgrowth, and adhering particles in quartz and zircon grains indicated a diagenetic environment and silica re-precipitation in a coastal environment. The association of mechanical (bulbous edge) and chemical (silica overgrowth, small and large solution pits) features in a single grain suggested a dual environment, that is, the combination of littoral and coastal environments. The sediments were also partly supplied by the coastal dunes located along the GoM coastal region and were redistributed by wave energy and littoral currents. Euhedral, subhedral, and unetched zircon grains in PBT and PT were mixed with rounded and etched grains, indicating a diverse provenance from crystalline rocks. In general, the microtextures identified on zircon and quartz grains reveal that sediments are influenced by wind, fluvial, and subaqueous marine environment and derived by nearby and distal sources.

Response solutions of 3-dimensional degenerate quasi-periodic systems with small parameter

This paper considers a class of 3-dimensional real analytic nonlinear quasi-periodic systems with a small perturbation parameter, whose unperturbed part has a degenerate equilibrium point. Based on the Leray-Schauder Continuation Theorem [18] , [20] and using technique of outer parameter, we prove that the system has a small response solution for many sufficiently small parameters.

Bounded and almost periodic solvability of nonautonomous quasilinear hyperbolic systems

The paper concerns boundary value problems for general nonautonomous first-order quasilinear hyperbolic systems in a strip. We construct small global classical solutions, assuming that the right-hand sides are small. In the case that all data of the quasilinear problem are almost periodic, we prove that the bounded solution is also almost periodic. For the nonhomogeneous version of a linearized problem, we provide stable dissipativity conditions ensuring a unique bounded continuous solution for any smooth right-hand sides. In the autonomous case, this solution is two times continuously differentiable. In the nonautonomous case, the continuous solution is differentiable under additional dissipativity conditions, which are essential. A crucial ingredient of our approach is a perturbation theorem for general linear hyperbolic systems. One of the technical complications we overcome is the “loss of smoothness” property of hyperbolic PDEs.

Quantitative evaluation of macromolecular crowding environment based on translational and rotational diffusion using polarization dependent fluorescence correlation spectroscopy

Macromolecular crowding (MMC) in cells is a hot topic in biology; therefore, well-characterized measurement standards for the evaluation of the nano-environment in MMC solutions are necessary. We propose to use polarization-dependent fluorescence correlation spectroscopy (Pol-FCS) for evaluation of macromolecular crowding in solutions. Pol-FCS can simultaneously measure the relaxation times of rotational and translational diffusion of fluorescent molecules at the same position, even in living cells with low damage. In this report, the differences in the nano-environment among solutions of small molecules, gels, and MMC solutions were evaluated by comparing their rotational and translational diffusion using Pol-FCS. Moreover, this method could distinguish the phase shift in the polyethylene glycol solution. Finally, we separately evaluated the nano-environment in the cytosol and nucleus of living cells in different cell lines and cell cycles. We expect this evaluation method to be useful in characterizing the nano-environment in MMC studies. In addition, the proposed method may be useful for other nano-environments such as liquid–liquid phase separation.

The effect of rotational degrees of freedom on solvation of nonpolar solute

We have studied the effect of rotational and translational degrees of freedom on solvation of nonpolar solutes. In this study a simple two-dimensional Mercedes-Benz (MB) water model was used. By separating temperature on rotational and translational part, the effect of different degrees of freedom on solvation was investigated. Increasing rotational temperature reduces tendency of water to form hydrogen bonds, therefore the effect of rotational degrees of freedom on solvation can be used to assess how hydrogen bonds affect solvation and what kind of liquid is more favourable for solvation of different solute. Considering the size there are three different regimes of solvation of nonpolar solutes and the effect of hydrogen bonds. The rotational temperature and thus hydrogen bonds have almost zero effect on solvation and aggregation of small solutes which are equally soluble in liquids that do and liquids that do not form hydrogen bonds. When size of solute is larger than HB length increasing rotational temperature improves solvation and diminishes association of solute molecules, thus large solutes are more soluble in liquids without hydrogen bonds. On the other hand when solute size is similar to HB length, increasing rotational temperature diminishes solvation and improves association of solute molecules, thus solutes of similar size are more soluble in liquid with hydrogen bonds, that means hydrogen bonds have favourable effect on solvation of such solutes. Hydrophobic effect appears only when solute is larger than HB length, on the other hand when solute size is similar to HB length inverse hydrophobic effect appears.

Various extensions in resource-constrained project scheduling with alternative subgraphs

In this research, we present several extensions for the resource-constrained project scheduling problem with alternative subgraphs (RCPSP-AS). First of all, we investigate more complex variants of the alternative project structure. More precisely, we consider nested alterative subgraphs, linked alternative branches, multiple selection, caused and closed choices, and split choices. Secondly, we introduce non-renewable resources in the RCPSP-AS in order to implicitly avoid certain combinations of alternatives given a limited availability of this resource over the complete project horizon. We formulate both the basic RCPSP-AS and its extensions as an ILP model and solve it using Gurobi. The computational experiments are conducted on a large set of artificial project instances as well as three case studies. The results show the impact of the different extensions on the project makespan and the computational complexity. We observe that combinations of the proposed extensions might imply complex alternative project structures, resulting in an increasing computational complexity or even infeasible solutions. The analysis of the three case studies shows that it is hard to find feasible solutions with a small time limit or optimal solutions with a larger time limit for projects with a realistic size in terms of the number of activities or alternatives.

Applications of isothermal titration calorimetry in pure and applied research from 2016 to 2020.

The last 5 years have seen a series of advances in the application of isothermal titration microcalorimetry (ITC) and interpretation of ITC data. ITC has played an invaluable role in understanding multiprotein complex formation including proteolysis-targeting chimeras (PROTACS), and mitochondrial autophagy receptor Nix interaction with LC3 and GABARAP. It has also helped elucidate complex allosteric communication in protein complexes like trp RNA-binding attenuation protein (TRAP) complex. Advances in kinetics analysis have enabled the calculation of kinetic rate constants from pre-existing ITC data sets. Diverse strategies have also been developed to study enzyme kinetics and enzyme-inhibitor interactions. ITC has also been applied to study small molecule solvent and solute interactions involved in extraction, separation, and purification applications including liquid-liquid separation and extractive distillation. Diverse applications of ITC have been developed from the analysis of protein instability at different temperatures, determination of enzyme kinetics in suspensions of living cells to the adsorption of uremic toxins from aqueous streams.

Optimal Dividend Strategy Under Parisian Ruin with Affine Penalty

In this paper, we investigate the optimal dividend problem under Parisian ruin with affine penalty payments at Parisian ruin time. The underlying risk process is assumed to be a spectrally negative Levy risk process. With the help of the dynamic programming principle, we prove that the value function associated to our optimal control problem is the smallest solution with certain characteristics to the corresponding Hamilton–Jacobi–Bellman (HJB) equation. In addition, the form of the performance function under barrier dividend strategy is expressed in terms of various extended scale functions. Then we identify a condition under which the performance function under certain barrier strategy is also a solution to the HJB equation, which in turn illustrates the optimalilty of such barrier dividend strategy among all admissible strategies. Various numerical examples are also given when the underlying risk process is compound Poisson process, Brownian motion with drift and jump-diffusion process.

The role of ESCRT-III and Annexin V in the repair of cell membrane permeabilization by the nanosecond pulsed electric field

Exposure of living cells to intense nanosecond pulsed electric field (nsPEF) increases membrane permeability to small solutes, presumably by the formation of nanometer-size membrane lesions. Mechanisms responsible for the restoration of membrane integrity over the course of minutes after nsPEF have not been identified. This study explored if ESCRT-III and Annexin V calcium-dependent repair mechanisms, which play critical role in resealing large membrane lesions, are also activated by electroporation and contribute to the membrane resealing. The extent of membrane damage and the time course of resealing were monitored by the time-lapse imaging of propidium (Pr) uptake in human cervical carcinoma (HeLa) cells exposed to trains of 300-ns PEF. The removal of the extracellular Ca2+ slowed down the resealing, although did not prevent it. Recruitment of CHMP4B protein, a component of ESCRT-III complex, to the electroporated plasma membrane was not observed, thus providing no evidence for possible contribution of the macro-vesicle shedding mechanism. In contrast, silencing the AnxA5 gene impaired resealing and reduced the viability of nsPEF-treated cells. We conclude that Annexin V but not ESCRT-III was involved in the repair of HeLa cells permeabilized by 300-ns stimuli, but it was not the only and perhaps not the main repair mechanism.

Focus on analytical equipment, spectroscopy, and spectrometry

Focus on analytical equipment, spectroscopy, and spectrometry

Bank Selection for SMEs: An Emirati Student Perspective

The focus of this research is to identify the factors that influence bank selection attitude amongst student entrepreneurs seeking financial support for their prospective business. The data generated from this study will not only apprise nascent Emirati entrepreneurs’ perspective but also emphasize the role of the banking industry, in particular the UAE Islamic Banks, in the development and growth of national SME sector. The target population size is set as 500 Emirati graduating students and the target sample size is set as 410. Descriptive Statistics, Test of Reliability and Factor Analysis methods are applied to the collected data to check the reliability and validity of the model. Statistical tools such as Multiple Regression and ANOVA are then applied to analyze the data. The study findings explore factors that impact the expectations of prospective Emirati entrepreneurs and their bank selection criteria. Additionally, the findings identify significant factors that UAE Islamic Banks can utilize to update their strategies towards attracting prospective customers and increasing their client base by adopting innovative small and medium enterprise (SME) financial solutions for the emerging Emirati entrepreneurs.

SGLT2 inhibition does not reduce glucose absorption during experimental peritoneal dialysis.

Unwanted glucose absorption during peritoneal dialysis (PD) remains a clinical challenge, especially in diabetic patients. Recent experimental data indicated that inhibitors of the sodium and glucose co-transporter (SGLT)-2 could act to reduce glucose uptake during PD, which raises the question of whether glucose absorption may also occur via intracellular or trans-cellular pathways. We performed PD in anesthetized Sprague-Dawley rats using a fill volume of 20 mL with either 1.5% glucose fluid or 4.25% glucose fluid for 120 min dwell time to evaluate the effects of SGLT2 inhibition by empagliflozin on peritoneal water and solute transport. To assess the diffusion capacity of glucose, we developed a modified equation to measure small solute diffusion capacity, taking convective- and free water transport into account. SGLT2 inhibition markedly increased the urinary excretion of glucose and lowered plasma glucose after PD compared to sham groups. Glucose absorption for 1.5% glucose was 165 mg 95% CI (145-178) in sham animals and 157 mg 95% CI (137-172) for empagliflozin-treated animals. For 4.25% glucose, absorption of glucose was 474 mg 95% CI (425-494) and 472 mg 95% CI (420-506) for sham and empagliflozin groups, respectively. No significant changes in the transport of sodium or water across the peritoneal barrier could be detected. We could not confirm recent findings that SGLT2 inhibition reduced glucose absorption and increased osmotic water transport during experimental PD.

Serum sodium variation is a major determinant of peridialytic blood pressure trends in haemodialysis outpatients

Intradialytic hypotension (IDH) and peridialytic blood pressure (BP) trends are associated with morbidity and mortality in haemodialysis (HD) patients. We aimed to characterise the respective influence of volume status and small solutes variation on peridialytic systolic BP (SBP) trends during HD. We retrospectively analysed the relative peridialytic SBP decrease in 647 prevalent outpatients attending for their mid-week session with corresponding pre- and post-HD bioelectrical impedance analysis. Mean SBP decreased by 10.5 ± 23.6 mmHg. Factors positively associated with the relative decrease in SBP were: serum sodium (Na) decrease, body mass index, serum albumin, dialysis vintage, ultrafiltration rate and urea Kt/V (p < 0.05 for all). Antihypertensive medications and higher dialysate calcium were negatively associated with the relative decrease in SBP (p < 0.05 for both). Age had a quadratic relationship with SBP trends (p < 0.05). Pre-HD volume status measured by extracellular to total body water ratio was not associated with SBP variation (p = 0.216). Peridialytic SBP trends represent a continuum with serum Na variation being a major determinant while volume status has negligible influence. Middle-aged and overweight patients are particularly prone to SBP decline. Tailoring Na and calcium dialysate concentrations could influence haemodynamic stability during HD and improve patient experience and outcomes.

Work Life Balance During Covid Pandemic

Work life balance has always been challenging to achieve for every individual working in different sector especially for women as it is not easy to do day to day chores at home and office work together while working from home. This paper intent to discover the mental and physical exhaustion and difficulties and challenges encountered by employees during pandemic and small solutions or advices for it. The existing problem has pushed the employees to increase their limits to fight in such situation. And have made them capable of managing both job and home under one roof leading more towards work life integration than work life balance. Employees who have accepted the changes and embraced it and have upgraded themselves with the digitalization are able to meet all the demands relating to time, home, family, work, health and responsibilities.

Size dependence of hydrophobic hydration at electrified gold/water interfaces

Hydrophobic hydration at metal/water interfaces actively contributes to the energetics of electrochemical reactions, e.g. [Formula: see text] and [Formula: see text] reduction, where small hydrophobic molecules are involved. In this work, constant applied potential molecular dynamics is employed to study hydrophobic hydration at a gold/water interface. We propose an adaptation of the Lum-Chandler-Weeks (LCW) theory to describe the free energy of hydrophobic hydration at the interface as a function of solute size and applied voltage. Based on this model we are able to predict the free energy cost of cavity formation at the interface directly from the free energy cost in the bulk plus an interface-dependent correction term. The interfacial water network contributes significantly to the free energy, yielding a preference for outer-sphere adsorption at the gold surface for ideal hydrophobes. We predict an accumulation of small hydrophobic solutes of sizes comparable to CO or [Formula: see text], while the free energy cost to hydrate larger hydrophobes, above 2.5-Å radius, is shown to be greater at the interface than in the bulk. Interestingly, the transition from the volume dominated to the surface dominated regimes predicted by the LCW theory in the bulk is also found to take place for hydrophobes at the Au/water interface but occurs at smaller cavity radii. By applying the adapted LCW theory to a simple model addition reaction, we illustrate some implications of our findings for electrochemical reactions.

Budding and Fission of Nanovesicles Induced by Membrane Adsorption of Small Solutes.

Membrane budding and fission are essential cellular processes that produce new membrane compartments during cell and organelle division, for intracellular vesicle trafficking as well as during endo- and exocytosis. Such morphological transformations have also been observed for giant lipid vesicles with a size of many micrometers. Here, we report budding and fission processes of lipid nanovesicles with a size below 50 nm. We use coarse-grained molecular dynamics simulations, by which we can visualize the morphological transformations of individual vesicles. The budding and fission processes are induced by low concentrations of small solutes that absorb onto the outer leaflets of the vesicle membranes. In addition to the solute concentration, we identify the solvent conditions as a second key parameter for these processes. For good solvent conditions, the budding of a nanovesicle can be controlled by reducing the vesicle volume for constant solute concentration or by increasing the solute concentration for constant vesicle volume. After the budding process is completed, the budded vesicle consists of two membrane subcompartments which are connected by a closed membrane neck. The budding process is reversible as we demonstrate explicitly by reopening the closed neck. For poor solvent conditions, on the other hand, we observe two unexpected morphological transformations of nanovesicles. Close to the binodal line, at which the aqueous solution undergoes phase separation, the vesicle exhibits recurrent shape changes with closed and open membrane necks, reminiscent of flickering fusion pores (kiss-and-run) as observed for synaptic vesicles. As we approach the binodal line even closer, the recurrent shape changes are truncated by the fission of the membrane neck which leads to the division of the nanovesicle into two daughter vesicles. In this way, our simulations reveal a nanoscale mechanism for the budding and fission of nanovesicles, a mechanism that arises from the interplay between membrane elasticity and solute-mediated membrane adhesion.

Aquaporins in platelet function

Structurally, aquaporins (AQPs) are small channel proteins with monomers of ~ 30 kDa that are assembled as tetramers to form pores on cell membranes. Aquaporins mediate the conduction of water but at times also small solutes including glycerol across cell membranes and along osmotic gradients. Thirteen isoforms of AQPs have been reported in mammalian cells, and several of these are likely expressed in platelets. Osmotic swelling mediated by AQP1 sustains the calcium entry required for platelet phosphatidylserine exposure and microvesiculation, through calcium permeable stretch-activated or mechanosensitive cation channels. Notably, deletion of AQP1 diminishes platelet procoagulant membrane dynamics in vitro and arterial thrombosis in vivo, independent of platelet granule secretion and without affecting hemostasis. Water entry into platelets promotes procoagulant activity, and AQPs may also be critical for the initiation and progression of venous thrombosis. Platelet AQPs may therefore represent valuable targets for future development of a new class of antithrombotics, namely, anti-procoagulant antithrombotics, that are mechanistically distinct from current antithrombotics. However, the structure of AQPs does not make for easy targeting of these channels, hence they remain elusive drug targets. Nevertheless, thrombosis data in animal models provide compelling reasons to continue the pursuit of AQP-targeted antithrombotics. In this review, we discuss the role of aquaporins in platelet secretion, aggregation and procoagulation, the challenge of drugging AQPs, and the prospects of targeting AQPs for arterial and venous antithrombosis.

Aquaporin: targets for dietary nutrients to regulate intestinal health.

Aquaporins (AQP) are a class of water channel membrane proteins that are widely expressed in the gut. The biological functions of aquaporins, which regulate the absorption and secretion of water molecules and small solutes, maintain the stable state of the intestine, regulate cell proliferation and migration, participate in the process of intestinal inflammation, and mediate tumorigenesis, demonstrate the physiological significance of these channels in intestinal health. The pathology of many intestinal diseases is associated with changes in the location and expression of aquaporins, such as intestinal infection, which can change the expression and distribution of AQPs in intestinal tissues/cells by affecting cytokines and chemokines. This can lead to various intestinal diseases such as diarrhoea, which also suggests the importance of aquaporins in the prevention and treatment of intestinal diseases. This review summarizes the relationship between aquaporins and intestinal physiology and diseases and focuses on drugs (such as plant extracts) or diets that can regulate intestinal health by regulating aquaporins. It provides a basis for establishing aquaporins as biomarkers and therapeutic targets for intestinal health.