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Journal of Biomechanics Feb 2024Nucleus pulposus (NP) tissue in the intervertebral disc (IVD) is a viscoelastic material exhibiting both solid- and fluid-like mechanical behaviors. Advances in...
Nucleus pulposus (NP) tissue in the intervertebral disc (IVD) is a viscoelastic material exhibiting both solid- and fluid-like mechanical behaviors. Advances in viscoelastic models incorporating fractional calculus, such as the Fractional Zener (FZ) model, have potential to describe viscoelastic behaviors. The objectives of this study were to determine whether the FZ model can accurately describe the shear viscoelastic properties of NP tissue and determine if the fractional order (α) is related to tissue hydration. 30 caudal IVDs underwent equilibrium dialysis in 5% or 25% polyethylene glycol solutions to alter tissue hydration. Excised NP tissue underwent stress relaxation testing in shear and unconfined compression. Stress relaxation data was fitted to the FZ model to obtain viscoelastic properties. In both loading modes, the initial modulus was greater for the less hydrated 25% equilibrated samples compared to 5% with no change in the equilibrium modulus. Samples with lower water content (25% samples) had shorter relaxation times in shear and longer time constants in compression, highlighting the different interactions between the fluid and solid matrix in loading modes. Samples with lower water content had α values closer to 0, indicating that less hydrated samples behaved more solid-like on the viscoelastic spectrum. Tissue hydration correlated with α values for 25% samples in shear. This study demonstrates that the FZ model may be used to describe IVD tissue behavior under both loading modes; however, the greatest utility of the FZ model is in describing flow-independent shear behaviors, and α may inform tissue hydration in shear.
Topics: Nucleus Pulposus; Intervertebral Disc; Elasticity; Stress, Mechanical; Water
PubMed: 38354514
DOI: 10.1016/j.jbiomech.2024.111965 -
Kidney Diseases (Basel, Switzerland) Feb 2024Chronic kidney disease (CKD) is associated with a high burden of coronary artery disease (CAD), which remains the leading cause of death in CKD patients. Despite the... (Review)
Review
BACKGROUND
Chronic kidney disease (CKD) is associated with a high burden of coronary artery disease (CAD), which remains the leading cause of death in CKD patients. Despite the high cardiovascular risk, ACS patients with renal dysfunction are less commonly treated with guideline-based medical therapy and are less frequently referred for coronary revascularization.
SUMMARY
The management of CAD is more challenging in patients with CKD than in the general population due to concerns regarding side effects and renal toxicity, as well as uncertainty regarding clinical benefit of guideline-based medical therapy and interventions. Patients with advanced CKD and especially those receiving dialysis have not traditionally been represented in randomized trials evaluating either medical or revascularization therapies. Thus, only scant data from small prospective studies or retrospective analyses are available. Recently published studies suggest that there are significant opportunities to substantially improve both cardiovascular and renal outcomes of patients with CAD and CKD, including new medications and interventions. Thus, the objective of this review is to summarize the current evidence regarding the management of CAD in CKD patients, in particular with respect to improvement of both cardiovascular and renal outcomes.
KEY MESSAGES
Adequate medical therapy and coronary interventions using evidence-based strategies can improve both cardiac and renal outcomes in patients with CAD and CKD.
PubMed: 38322630
DOI: 10.1159/000533970 -
Annals of Ibadan Postgraduate Medicine Aug 2023During our posting at the Renal Unit, Department of Medicine, University College Hospital, Ibadan, we observed numerous difficulties encountered by patients requiring...
INTRODUCTION
During our posting at the Renal Unit, Department of Medicine, University College Hospital, Ibadan, we observed numerous difficulties encountered by patients requiring renal replacement therapy and the family members/caregivers of these patients. These are broadly categorized into patents' related challenges, institutional inadequacies, infrastructural challenges, policy, and funding issues.
PERSPECTIVE
Patients' challenges are poor health-seeking habits culminating in late diagnosis in advanced uremic state and poor economic status resulting in catastrophic out-of-pocket spending. Institutional and infrastructural challenges include epileptic power supply in the dialysis unit, a lack of necessary materials needed for dialysis, among others. Policy issues included the absence of an organ donor system and regulations guiding them. More importantly, there is insufficient support from the government concerning patients with end-stage kidney disease.
CONCLUSION
Tackling the management of end-stage kidney disease would require paying attention to and addressing these challenges.
PubMed: 38298348
DOI: No ID Found -
Scientific Reports Jan 2024Recent studies have suggested benefits for time-dependent dialysate bicarbonate concentrations (D) during hemodialysis (HD). In this clinical trial, we compared for the... (Clinical Trial)
Clinical Trial
Recent studies have suggested benefits for time-dependent dialysate bicarbonate concentrations (D) during hemodialysis (HD). In this clinical trial, we compared for the first time in the same HD patients the effects of time-dependent changes with constant D on acid-base and uremic solute kinetics. Blood acid-base and uremic solute concentration were measured in twenty chronic HD patients during 4-h treatments with A) constant D of 35 mmol/L; B) D of 35 mmol/L then 30 mmol/L; and C) D of 30 mmol/L then 35 mmol/L (change of D after two hours during Treatments B and C). Arterial blood samples were obtained predialysis, every hour during HD and one hour after HD, during second and third treatments of the week with each D concentration profile. Blood bicarbonate concentration (blood [HCO]) during Treatment C was lower only during the first three HD hours than in Treatment A. Overall blood [HCO] was reduced during Treatment B in comparison to Treatment A at each time points. We conclude that a single change D in the middle of HD can alter the rate of change in blood [HCO] and pH during HD; time-dependent D had no influence on uremic solute kinetics.
Topics: Humans; Bicarbonates; Dialysis Solutions; Kidney Failure, Chronic; Renal Dialysis
PubMed: 38281975
DOI: 10.1038/s41598-024-52757-2 -
BMC Nephrology Jan 2024Patients taking SGLT-2 inhibitors may experience delayed peritoneal fibrosis, better ultrafiltration of water and toxins, and higher survival rates. We aimed to evaluate...
BACKGROUND
Patients taking SGLT-2 inhibitors may experience delayed peritoneal fibrosis, better ultrafiltration of water and toxins, and higher survival rates. We aimed to evaluate the possible effects of Dapagliflozin in changing the peritoneal solute transfer rate, reducing peritoneal glucose absorption, and, hence, increasing ultrafiltration.
METHODOLOGY
A pilot pre-post interventional study was used to evaluate 20 patients on continuous ambulatory peritoneal dialysis (CAPD) enrolled in a one-month self-controlled study [Trial#: NCT04923295]. Inclusion criteria included being over 18, and having a Peritoneal Dialysis (PD) vintage of at least six months. All participants were classified as having high or average high transport status based on their Peritoneal Equilibrium Test with a D0/D4 > 0.39. and using at least two exchanges with 2.35% dextrose over the previous three months before enrollment.
RESULTS
Following the treatment, 13 patients had an increase in median D4/D0 from 0.26 [0.17-0.38] to 0.31 [0.23-0.40], while seven patients had a decline from 0.28 [0.17-0.38] to 0.23 [0.14-0.33]. Additionally, nine patients had a decrease in median D/P from 0.88 [0.67-0.92] to 0.81 [0.54-0.85], while 11 patients had an increase from 0.70 [0.6-0.83] to 0.76 [0.63-0.91].
CONCLUSION
According to the findings of this study, Dapagliflozin usage in peritoneal dialysis patients did not result in a reduction in glucose absorption across the peritoneal membrane. Additionally, Dapagliflozin was also associated with a small increase in sodium dip, a decrease in peritoneal VEGF, and a decrease in systemic IL-6 levels all of which were not statistically significant. Further large-scale studies are required to corroborate these conclusions.
Topics: Humans; Pilot Projects; Peritoneum; Peritoneal Dialysis; Ultrafiltration; Glucose; Dialysis Solutions; Benzhydryl Compounds; Glucosides
PubMed: 38279109
DOI: 10.1186/s12882-023-03429-2 -
Scientific Reports Jan 2024Copper (Cu) is a cofactor in numerous key proteins and, thus, an essential element for life. In biological systems, Cu isotope abundances shift with metabolic and...
Copper (Cu) is a cofactor in numerous key proteins and, thus, an essential element for life. In biological systems, Cu isotope abundances shift with metabolic and homeostatic state. However, the mechanisms underpinning these isotopic shifts remain poorly understood, hampering use of Cu isotopes as biomarkers. Computational predictions suggest that isotope fractionation occurs when proteins bind Cu, with the magnitude of this effect dependent on the identity and arrangement of the coordinating amino acids. This study sought to constrain equilibrium isotope fractionation values for Cu bound by common amino acids at protein metal-binding sites. Free and bound metal ions were separated via Donnan dialysis using a cation-permeable membrane. Isotope ratios of pre- and post-dialysis solutions were measured by MC-ICP-MS following purification. Sulfur ligands (cysteine) preferentially bound the light isotope (Cu) relative to water (ΔCu = - 0.48 ± 0.18‰) while oxygen ligands favored the heavy isotope (Cu; + 0.26 ± 0.04‰ for glutamate and + 0.16 ± 0.10‰ for aspartate). Binding by nitrogen ligands (histidine) imparted no isotope effect (- 0.01 ± 0.04‰). This experimental work unequivocally demonstrates that amino acids differentially fractionate Cu isotopes and supports the hypothesis that metalloprotein biosynthesis affects the distribution of transition metal isotopes in biological systems.
Topics: Amino Acids; Copper; Metalloproteins; Renal Dialysis; Glutamic Acid; Isotopes; Antifibrinolytic Agents
PubMed: 38253574
DOI: 10.1038/s41598-024-52091-7 -
Membranes Dec 2023This study presents the possibility of using diffusion dialysis for the separation of inorganic acids (hydrochloric, nitric, and hydrofluoric) and their ferric salts...
This study presents the possibility of using diffusion dialysis for the separation of inorganic acids (hydrochloric, nitric, and hydrofluoric) and their ferric salts whose composition corresponds to that of real spent pickling solutions. At a steady state, the transport properties of three different anion-exchange membranes (Fumasep-FAD, Neosepta-AFN, and Neosepta-AHA) are compared using a continuous counter-current dialyzer. At a constant composition of the solutions (acid concentration 3 mol L and iron concentration 30-40 g L), the effects of volumetric liquid flow rates on the transport rate of H and Fe ions through the membrane are studied. The dialysis process is characterized by the recovery of acids and the rejection of salts. Furthermore, the values of the dialysis coefficients of acids, iron, and the acid/iron separation factors are calculated and compared. The volumetric flow rates of the inlet streams change in limits from 3 × 10 to 6 × 10 m s (from 3 to 6 L h m, relative to the membrane area). A comparison of the tested membranes shows slightly better results for acid recovery, iron rejection, and acid/iron separation factors for the Fumasep-FAD membrane than for the Neosepta-AFN membrane. However, the results obtained show that both of these anion-exchange membranes can be considered good separators for tested mixtures that simulate real spent pickling solutions, and there is a good precondition for using diffusion dialysis for processing these solutions in industrial practice. On the contrary, very low values of acid recovery and the overall dialysis coefficient of acid are found for the Neosepta-AHA membrane in the test range of the volumetric flow rate, and, thus, this membrane is insufficient for the adequate separation of these acids and iron salts.
PubMed: 38248696
DOI: 10.3390/membranes14010006 -
Nefrologia 2023The sodium gradient during hemodialysis sessions is one of the key factors in sodium balance in patients with dialysis-dependent chronic kidney disease; however, until...
INTRODUCTION
The sodium gradient during hemodialysis sessions is one of the key factors in sodium balance in patients with dialysis-dependent chronic kidney disease; however, until the appearance of the new monitors with sodium modules, the differences between prescribed and measured sodium have been understudied. The present study aimed to compare the impact on the measured conductivity and the initial and final plasma sodium after changing the 5008 Cordiax to the new 6008 Cordiax monitor.
MATERIAL AND METHODS
106 patients on hemodialysis were included. Each patient underwent 2 dialysis sessions in which only the monitor was varied. The variables collected were dialysate, sodium and bicarbonate prescribed, real conductivity, initial and final plasma sodium measured, and the calculated sodium gradient (ΔPNa).
RESULTS
The change of dialysis monitor showed small but statistically significant differences in the initial (138.14mmol/L with 5008 vs. 138.81mmol/L with 6008) and final plasma sodium (139.58mmol/L vs. 140.97mmol/L), as well as in the actual conductivity obtained (13.97 vs. 14.1mS/cm). The ΔPNa also increased significantly.
CONCLUSION
The change from 5008 to 6008 monitor is associated with increased conductivity, leading the patient to end the sessions with higher plasma sodium and ΔPNa. Knowing and confirming this change will allow us to individualize the sodium prescription and avoid possible undesirable effects. It could be the preliminary study to explore the new sodium biosensor incorporated into the new generation of monitors.
Topics: Humans; Renal Dialysis; Sodium; Dialysis Solutions
PubMed: 38242765
DOI: 10.1016/j.nefroe.2024.01.006 -
Journal of Artificial Organs : the... Jun 2024Excessive albumin losses during HC (haemocatharsis) are considered a potential cause of hypoalbuminemia-a key risk factor for mortality. This review on total albumin... (Review)
Review
Excessive albumin losses during HC (haemocatharsis) are considered a potential cause of hypoalbuminemia-a key risk factor for mortality. This review on total albumin losses considers albumin "leaking" into the dialysate and losses due to protein/membrane interactions (i.e. adsorption, "secondary membrane formation" and denaturation). The former are fairly easy to determine, usually varying at the level of ~ 2 g to ~ 7 g albumin loss per session. Such values, commonly accepted as representative of the total albumin losses, are often quoted as limits/standards of permissible albumin loss per session. On albumin mass lost due to adsorption/deposition, which is the result of complicated interactions and rather difficult to determine, scant in vivo data exist and there is great uncertainty and confusion regarding their magnitude; this is possibly responsible for neglecting their contribution to the total losses at present. Yet, many relevant in vitro studies suggest that losses of albumin due to protein/membrane interactions are likely comparable to (or even greater than) those due to leaking, particularly in the currently favoured high-convection HDF (haemodiafiltration) treatment. Therefore, it is emphasised that top research priority should be given to resolve these issues, primarily by developing appropriate/facile in vivo test-methods and related analytical techniques.
Topics: Humans; Dialysis Solutions; Hemodiafiltration; Hypoalbuminemia; Renal Dialysis; Serum Albumin
PubMed: 38238597
DOI: 10.1007/s10047-023-01430-y -
ClinicoEconomics and Outcomes Research... 2024Approximately 24% of hospitalized stage 2-3 acute kidney injury (AKI) patients will develop persistent severe AKI (PS-AKI), defined as KDIGO stage 3 AKI lasting ≥3...
BACKGROUND
Approximately 24% of hospitalized stage 2-3 acute kidney injury (AKI) patients will develop persistent severe AKI (PS-AKI), defined as KDIGO stage 3 AKI lasting ≥3 days or with death in ≤3 days or stage 2 or 3 AKI with dialysis in ≤3 days, leading to worse outcomes and higher costs. There is currently no consensus on an intervention that effectively reverts the course of AKI and prevents PS-AKI in the population with stage 2-3 AKI. This study explores the cost-utility of biomarkers predicting PS-AKI, under the assumption that such intervention exists by comparing C-C motif chemokine ligand 14 (CCL14) to hospital standard of care (SOC) alone.
METHODS
The analysis combined a 90-day decision tree using CCL14 operating characteristics to predict PS-AKI and clinical outcomes in 66-year-old patients, and a Markov cohort estimating lifetime costs and quality-adjusted life years (QALYs). Cost and QALYs from admission, 30-day readmission, intensive care, dialysis, and death were compared. Clinical and cost inputs were informed by a large retrospective cohort of US hospitals in the PINC AI Healthcare Database. Inputs and assumptions were challenged in deterministic and probabilistic sensitivity analyses. Two-way analyses were used to explore the efficacy and costs of an intervention preventing PS-AKI.
RESULTS
Depending on selected costs and early intervention efficacy, CCL14-directed care led to lower costs and more QALYs (dominating) or was cost-effective at the $50,000/QALY threshold. Assuming the intervention would avoid 10% of PS-AKI complications in AKI stage 2-3 patients identified as true positive resulted in 0.066 additional QALYs and $486 reduced costs. Results were robust to substantial parameter variation.
CONCLUSION
The analysis suggests that in the presence of an efficacious intervention preventing PS-AKI, identifying people at risk using CCL14 in addition to SOC is likely to represent a cost-effective use of resources.
PubMed: 38235419
DOI: 10.2147/CEOR.S434971