bluuebunny/crossref_metadata_2025_split huggingface dataset:
#2651 Microwave tissue digestion and flame atomic absorption spectroscopy for measuring tissue sodium content in CKD patients
Authors: van Duin Robert , Oppelaar Marjet , Heisel Annalena , Annor Ataa Akua Kromo , Wouda Rosa , van Zuilen Kirsten , Naessens Daphne , De Vos Judith , Bakker Erik , Hagner Matthias , Engberink Rik Olde , Vogt Liffert 
Published: May 2024

Abstract

Background and Aims
Skin and muscle sodium accumulation has been demonstrated in CKD patients and may contribute to progression of the disease. Various methods are available for measuring tissue sodium content. However, the accuracy and reproducibility of these methods remain unknown. Dry ashing is the most used digestion method, but is expensive, time consuming and has a risk of incomplete digestion. This study compared microwave digestion, dry ashing, and two electrolyte quantification methods for quantifying tissue sodium and potassium.

Method
We compared microwave digestion (Ethos LEAN Compact Microwave Digestion System, Milestone SRL) and dry ashing (Nabertherm S27) as sample preparation methods, and flame atomic absorption spectroscopy (FAAS, Model 425 Flame Photometer, Sherwood Scientific) and inductively coupled plasma optical emission spectrometry (ICP-OES, Varian 720-ES, Varian Inc.) as electrolyte quantification methods. Skin and muscle samples were obtained from rats and mice, and human skin samples were used. Tissues biopsies were cut in three pieces and digested separately. The methods were compared using interclass correlation coefficient (ICC) and Bland-Altman analysis. The third piece of tissue was microwave-digested by another operator to test inter-operator reproducibility by calculating the ICC and absolute overall mean difference.

Results
With microwave digestion and FAAS median (IQR) human skin concentration was 114.8 (99.2-157.0, n = 12) mmol/L, confirming tissue sodium storage. When including all tissues, FAAS and ICP-OES showed high agreement for sodium (ICC 0.98, bias –0.00008 mmol/g, n = 141 and potassium (ICC 0.98, bias –0.005 mmol/g, n = 141). Microwave digestion and ashing showed agreement for sodium (ICC 0.93, bias –0.002 mmol/g, n = 61) and potassium (ICC 0.93, bias –0.02 mmol/g, n = 61). The inter-operator agreement was good for sodium (ICC 0.95, absolute mean difference (SD) 0.044 mmol/g (0.073), n = 70) and potassium (ICC 0.96, absolute mean difference (SD) 0.031 mmol/g (0.032), n = 70).

Conclusion
Microwave digestion with FAAS is a reliable and consistent method for sodium and potassium trace analysis in animal and human tissues compared to ashing and ICP-OES, respectively. This method showed more quantification of cations than the most frequently reported method, representing an easier, and less time-consuming way to quantify tissue sodium in CKD research.
#1825 Treating hyperphosphatemia in CKD via targeting Npt2a in the kidney
Authors: Rieg Timo 
Published: May 2024

Abstract

Background and Aims
Targeting the renal sodium phosphate cotransporter 2a (Npt2a) offers a novel strategy for treating hyperphosphatemia in chronic kidney disease (CKD). In patients with and without reduced kidney function, hyperphosphatemia is associated with cardiovascular complications and currently treatment options are limited.

Method
To study the role of a novel Npt2a inhibitor (PF-06869206) we used in vitro (Opossum kidney [OK] cells) and in vivo approaches (C57Bl/6 and Npt2a knockout [Npt2a−/−] mice). As models of CKD, 5/6 nephrectomy (5/6 Nx) as well as novel Alport/Npt2a knockout mice (Alport/Npt2a−/−) were studied.

Results
OK cell experiments showed that the Npt2a inhibitor caused dose-dependent reductions of Na+-dependent Pi uptake (IC50: ∼1.4 μmol/L) and Michaelis-Menten kinetics identified a ∼2.4-fold higher Km for Pi in response to Npt2a inhibition with no significant change in apparent Vmax, indicating a competitive mode of action. In vivo, Npt2a inhibition enhanced urinary excretions of Pi, Ca2+, and Na+ dose-dependently, which is recapitulated in animal models with reduced kidney function (5/6 Nx and Alport mice). Reductions in plasma Pi occur within 30 minutes and reach a maximum (40-50%) after 2 hours, this coincided with ∼50% reductions in PTH levels. No effects on FGF23 were observed in this time frame. In C57Bl/6 mice qualitative immunohistochemistry after 24 hours showed reductions in Npt2a labelling in apical microvilli compared to vehicle treatment. Providing proof of concept, Npt2a−/− and Alport/Npt2a−/− mice confirmed specificity of the drug, effects on urinary and plasma Pi were absent. Further electrophysiological studies in acutely isolated connecting tubule/cortical collecting duct showed that open probability of the epithelial Na+ channel (ENaC) was reduced in response to Npt2a inhibition, suggesting that the natriuretic effect is mediated, at least in part, by inhibition of ENaC.

Conclusion
Npt2a inhibition offers a promising therapeutic approach for treating hyperphosphatemia and possibly offers the opportunity of reducing cardiovascular complications in CKD.
#1496 High levels of sclerostin promote bone resorption and changes and mineral metabolism
Authors: Muñoz-Castañeda Juan R , Ortiz Maria Encarnacion Rodriguez , Diaz-Tocados Juan Miguel , Romero Ana Torralbo , Lopez-Baltanas Rodrigo , Jurado Daniel , Garcia-Saez Raquel , Naves-Díaz Manuel , Alonso-Montes Cristina , Victoria Pendon-Ruiz de Mier M , Rodelo-Haad Cristian , Rodriguez Mariano 
Published: May 2024

Abstract

Background and Aims
The physiological function of sclerostin (SOST) remains unknown. It is known that SOST is produced in osteocytes and functions as an inhibitor of the Wnt/β-catenin pathway. Similarly, it is well-established that low levels of SOST lead to bone alterations affecting cortical bone, resulting in osteopetrosis and reduced calciuria. High levels of SOST are associated with osteoporosis.
In this study, we aimed to investigate the impact of three elevated doses of SOST on cortical, trabecular, and subchondral bone, as well as its relationship with other parameters of mineral metabolism.

Method
Bone histomorphometry, mCT, immunohistochemistry, and analysis of mineral metabolism parameters revealed that high doses of SOST over a 14-day period led to a reduction in trabecular bone volume due to a significant increase in bone resorption through the direct activation of osteoclastogenesis.

Results
Bone resorption, as measured by TRAP activity, was higher in trabecular, cortical, and subchondral bone. Similarly, high doses of SOST increased the number of hypertrophic chondrocytes, consequently expanding the growth plate area. Cortically, positive TRAP staining was observed, suggesting osteocytic osteolysis and trabecularization of cortical bone. The increased bone resorption resulted in a substantial rise in urinary excretion of phosphorus and calcium, accompanied by elevated levels of FGF23 and a significant decrease in PTH.

Conclusion
The findings suggest that elevated levels of SOST promote bone resorption through the activation of osteoclasts and the generation of osteocytic osteolysis. The increase in calcium and phosphorus levels led to changes in mineral metabolism, indicating a close relationship between SOST and other mineral metabolism parameters.
#2215 Early molecular and cellular features of aortic remodeling in a mild CKD-MBD model with low bone turnover
Authors: Bogdanova Evdokia , Beresneva Olga , Zubina Irina , Kutikhin Anton , Dobronravov Vladimir 
Published: May 2024

Abstract

Background and Aims
Vascular calcification associated with a maladaptive bone response is common in CKD and is a major cause of mortality (up to 60% depending on CKD stage). Alterations in several intracellular signaling pathways have been reported during the cellular phenotype transition and vascular calcification, however the initial phases of vascular remodeling in early CKD-MBD remain poorly understood. The aim of this study was to investigate the early molecular and cellular features of aortic remodeling prior to calcification in a model of mild CKD-MBD with low bone turnover.

Method
We induced CKD-MBD by 3/4 nephrectomy (Nx, n = 8) in adult male spontaneously hypertensive rats (SHR) with normal phosphate (Pi) intake (0.6%). Controls were sham-operated Wistar rats (n = 8) and SHR (n = 8). Chronic kidney injury and Pi exchange parameters, serum levels of calciprotein particles (CPPs), intact PTH, intact FGF23, dickkopf-1 and sclerostin, static bone histomorphometry, aortic morphology (H&E, Masson's trichrome, calcein, von Kossa stain), CD31, aSMA, nestin, Col1a1, PDGFR-beta, PiT1, LGR4 and intracellular signaling molecules—phospho-ERK1/2, active (non-phospho) beta-catenin, Hes1, Gli1 were analyzed by IHC with quantitative morphometry and IF after 4 months. Confocal microscopy was performed at the Centre for Collective Use of the Pavlov Institute of Physiology, Russian Academy of Sciences (Zeiss LSM 710).

Results
The study found that Nx rats with chronic kidney injury comparable to human CKD S2 exhibited lower bone turnover (Fig. 1). The Nx group had higher serum levels of Pi and CPPs vs. control group, but there were no differences in Pi-regulatory factors (Figs 1, 2b). Additionally, the Nx group showed aorta remodeling, which was characterized by an increase in intima thickness, cellularity, and collagen accumulation in the medial layer (Figs 1, 2a). The histological parameters of intimal remodeling and perivascular fibrosis were found to be directly correlated with serum levels of Pi and CPPs. In Nx, there was a decrease in medial αSMA expression accompanied by an increase in phospho-ERK1/2, PiT1, nestin, Gli1, beta-catenin, dickkopf-1, and an decrease in Hes1 immunomorphological staining (Figs 1, 2a, c). αSMA-negative cells demonstrated the expression of osteogenesis-related molecules, such as phospho-ERK1/2 (Fig. 2a, c), and occasionally, RunX2 (Fig. 2a). Phospho-ERK1/2 and PiT1 were found to co-localize in Nx (Fig. 2c). Intimal remodeling was observed, characterized by increased beta-catenin and nestin expression (Fig. 2c).

Conclusion
In mild CKD-MBD with low bone turnover, early intimal and medial aortic remodeling was associated with higher serum Pi and CPPs levels, and upregulation of PiT1, ERK1/2. In addition, other signals likely related to osteogenesis (RunX2, LGR4) and regulation of vascular progenitor cells (Nestin, Wnt, Notch, Hedgehog) may be implicated.
#1756 Development and internal validation of machine learning algorithms for mortality prediction model of people with DM and CKD
Authors: Zou Yutong , Liu Fang 
Published: May 2024

Abstract

Background and Aims
Diabetes Mellitus (DM) and Chronic Kidney Disease (CKD) are leading causes of morbidity and mortality, presenting challenges in patient management. The aim of this study is to develop a machine learning-based predictive model for mortality in DM and CKD patients, improving early intervention and treatment personalization.

Method
3,637 participants with DM and CKD from the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2018 were included. All-cause mortality was ascertained by linkage to National Death Index records through 31 December 2019 in NHANES. The dataset included clinical profiles, demographic details, and laboratory results of patients with DM and CKD. We performed 100 random groupings, dividing the data into a 75% training set and a 25% validation set each time. We then visualized the results of 100 AUC measurements using a boxplot. The objective was to forecast patient survival over 1, 3, 5, and 10-year horizons using a variety of machine learning algorithms. The algorithms tested included Logistic Regression (LR), Decision Tree (DT), Random Forest (RF), K-Nearest Neighbors (KNN), Gaussian Naive Bayes (GNB), Multinomial Naive Bayes (MNB), Bayesian Network Classifier (BNC), AdaBoost (Ada), Gradient Boosting (Gradient), and Extreme Gradient Boosting (XG). The performance of each algorithm was evaluated based on the Area Under the Receiver Operating Characteristic (ROC) Curve (AUC), with the results visualized in boxplot format.

Results
Upon result shown as the boxplots, it becomes evident that the Random Forest (RF) algorithm consistently exhibits one of the highest AUCs on average across all prediction intervals, suggesting a strong and stable predictive capacity. In the 1-year survival prediction, the RF algorithm demonstrates a highest AUC, implying consistent performance. The 3 and 5-year predictions reveal a slight dip in AUC for most models, including RF, but it still remains one of the top-performing algorithms with fewer outliers than XG and Gradient Boosting. The mean AUC of RF is particularly noteworthy at the 10-year mark, where most algorithms struggle with prediction accuracy, as indicated by lower median AUCs and greater variability. Notably, the RF algorithm identified six major factors for 1-year survival prediction: systolic blood pressure, uric acid, blood urea nitrogen, lactate dehydrogenase, lymphocyte count and total cholesterol, as well as three major factors for 10-year survival prediction: age, lymphocyte and gamma-glutamyl transferase.

Conclusion
Overall, the study indicates that while machine learning can be a powerful tool for survival prediction in patients with DM and CKD, the choice of algorithm is crucial, with RF standing out for its consistent and reliable performance.
#963 Discrepancy between actual and estimated urine creatinine excretion predicts mortality in chronic kidney disease: from the KNOW-CKD study
Authors: Kim Yujung , Lee Ju Young , Huh Daseul , Kim Keonhwa , Yang Jihyun , Lee Kyu-Beck , Kim Hyang , Oh Kook-Hwan , Hyun Young Youl 
Published: May 2024

Abstract

Background and Aims
Urine creatinine excretion is a surrogate marker of muscle mass and low urine creatinine excretion is a predictor of poor clinical outcome. There are several methods to estimate urine creatinine excretion. However, little is known about the clinical implication of discrepancy between actual and estimated urine creatinine excretion in chronic kidney disease (CKD). The aim of this study is to investigate the association between actual and estimated urine creatinine excretion discrepancy and mortality in CKD.

Method
This study analysed 1805 participants from the KNOW-CKD cohort. They underwent 24-hr urine collection and measured urine creatinine excretion at baseline. Their estimated urine creatinine excretion was calculated by Joachim's method. Discrepancy between actual and estimated urine creatinine excretion (dUCr) was defined as actual urine creatinine excretion minus estimated urine creatinine excretion. Patients were divided into 3 groups according to their tertile of dUCr. The study endpoint was all-cause death.

Results
During a follow-up of 13 062 person-years (median 8.0 years), 151 patients (8.4%) died, with a corresponding death rate of 11.6 (95% CI 9.9-13.6) per 1000 patients-years. 86 (14.4%), 41 (6.8%) and 24 (3.4%) patients from each 1st to 3rd tertile of dUCr died (P &lt; 0.001). In multivariate Cox proportional hazard analysis, there was a graded association of dUCr with all-cause mortality. The adjusted hazard ratios (95% CI) of 2nd and 3rd tertile were 0.58 (0.39-0.86) and 0.36 (0.22-0.58) compared with the 1st tertile.

Conclusion
Higher discrepancy between actual and estimated urine creatinine excretion is associated with lower risk of mortality in predialysis CKD patients. This association was independent of various conventional and CKD-related risk factors.
#2134 Very low protein integrated diet (sVLPD), without keto analogues, in patients with advanced chronic renal failure: clinical and economic benefits
Authors: Cecchi Sofia , Distante Silvio , Diluca Marina 
Published: May 2024

Abstract

Background and Aims
The integrated very low protein diet (sVLPD) has proven effective in slowing the progression of stage 5 chronic renal failure and in postponing the start of dialysis treatment (1)SVLPD with keto analogues is difficult to implement due to the high number of tablets to be taken (2), therefore, to increase compliance we decided to prescribe, in compliance with the guidelines of normal clinical practice, SVLPD (0.3 g/prot/day) integrated with only essential amino acid drugs without the use of keto analogues, in stage 5 patients and we have verified its effectiveness, safety and clinical and economic effects(3).

Method
129 patients were started on dietary therapy (middle age 75.2 ± 13.7, 60.5%male, all with hypertension, 40.3% with diabetes and 24.8% with heart disease) who were tested at the beginning of the observation, every 3 months and for 24 months, characterizing blood chemistry tests and body composition (with impedance analysis).

Results
During the 24-month observation period 91 patients (70.5%) were compliant with dietary therapy. Chronic kidney disease progression is slowed with average eGFR 11.6 ± 3.3 (compliant) vs. 9.3 ± 2.7 (no compliant) mL/min/1.73 m2, p &lt; 0.001) Urea (mg/dL) 116.1 ± 31.7 (compliant) 174.2 ± 42.2 (no compliant) p &lt; 0.002; and initiation of dialysis treatment (adjusted HR = 0.361, CI 0.200–0.650, p = 0.001) was delayed without evidence of malnutrition, in compliant versus noncompliant patients. Metabolic acidosis was well compensated in both groups with an improving trend in bicarbonate levels in compliant patients. Hemoglobin, uricemia, serum albumin, glycemia (downward trend NS), potassium, sodium, chlorium, calcium, magnesium, pH, lipids remained within normal values. Better blood pressure control was observed in compliant patients compared to non-compliant patients (SBP (mmHg) 136.9 ± 11.8 vs 150.1 ± 7 &lt;0.01), DBP (mmHg) 75 ± 3.1 vs 79.4 ± 1 &lt;0.001) During the observation, there were 24 deaths (13 patients older than 85 years), 20 peritoneal dialysis hospitalizations, 36 hemodialysis hospitalizations, 4 preventive living transplants and 15 renal functional recoveries with eGFR consistently &gt;15 mL/min/ 1.73 m2. The months of dialysis avoided generated gross savings in terms of healthcare expenditure equal to EUR 3,076,470; the expenditure sustained by the Marche region for protein-free products (EUR 90 per patient per month) was EUR 158,358. As a result, the total net savings were EUR 2,918,112.

Conclusion
This non-interventional longitudinal observational study is part of standard clinical practice and suggests that VLPD supplemented with only essential amino acids is safe and effective and could be widely used to reduce the incidence of dialysis treatments, with a favorable economic impact on the National Health Service.
#1375 Association of NT-proBNP and kidney function progression in chronic kidney disease patients without heart failure
Authors: Lu Yi , Chen Junzhe , Lukwaro Andrew Fanuel , Fu Sha , Hou Fan Fan , Nie Sheng , Tang Ying 
Published: May 2024

Abstract

Background and Aims
Elevated N-terminal pro-B-type natriuretic peptide (NT-proBNP) is reported to be associated with higher risk of decline in kidney function. However, little evidence exists about the relationship between NT-proBNP and kidney function progression stratified by estimated glomerular filtration rate (eGFR) in chronic kidney disease (CKD) patients without heart failure. Therefore, we aim to investigate the association of NT-proBNP and CKD progression in different CKD stages for CKD patients without heart failure.

Method
A multicentric retrospective cohort study recruited 23860 patients diagnosed with CKD from China Renal Data System (CRDS) database. Eligible participants were classified into five groups according to eGFR. CKD progression was defined as a composite of an increase in serum creatinine ≥50% or a decrease in eGFR ≥40% from baseline or a need for kidney replacement therapy. A linear regression model evaluated the relationship between eGFR and NT-proBNP. Cox regression analysis assessed the association between NT-proBNP and CKD progression. We also performed restricted cubic spline (RCS) and threshold effect analysis to investigate non-linear relationships between NT-proBNP and CKD progression.

Results
In a linear regression model, NT-proBNP was negatively correlated with eGFR in CKD patients. Each decrease of 15 ml/min/1.73 m2 in eGFR was associated with 1.06-fold, 1.50-fold, 1.52-fold, 1.94-fold, 3.37-fold higher levels of log (NT-proBNP) in CKD patients with stage 1-2, 3a, 3b, 4 and 5 respectively. In the multivariable Cox hazard model, elevated NT-proBNP was associated with a greater risk of kidney function progression, particularly among CKD stage 3 patients (stage 3a: HR, 1.42, 95% CI, 1.32-1.53; stage 3b: HR, 1.43, 95% CI, 1.32-1.54), with P-interaction≤0.001. However, the correlation of NT-proBNP and CKD progression had no statistical significance among CKD patients with stages 4-5 after sensitivity analyses. RCS and two-segment Cox regression model showed reversed L-shaped non-linear relationships between NT-proBNP and CKD progression in CKD patients with stages 1-4, with the inflection point at 250 pg/mL, 750 pg/mL, 653 pg/mL, 526 pg/mL, but not in stage 5 (Figure).

Conclusion
NT-proBNP may be a reliable biomarker to predict CKD progression in stages 1-3 CKD (mainly for stage 3) without heart failure. This helps clinicians predict a decline in kidney function early and set the threshold for therapy. However, the predictive role of NT-proBNP in in advanced CKD patients is insignificant.
#2422 Iohexol plasma clearance measurement protocol standardization—a consensus of the European Kidney Function Consortium
Authors: Ebert Natalie , Schaeffner Elke , Seegmiller Jesse C , van Londen Marco , Bökenkamp Arend , Cavalier Etienne , Delanaye Pierre , Derain-Dubourg Laurence , Eriksen Bjørn O , Pálsson Runólfur , Shafi Tariq , White Christine A 
Published: May 2024

Abstract

Background and Aims
International consensus supports the development of standardized protocols for measured glomerular filtration rate (mGFR) to facilitate the adoption of mGFR determination in both clinical and research settings.

Method
The European Kidney Function Consortium (EKFC) convened an international group of mGFR experts. The working group performed an extensive literature search to inform the development of recommendations for mGFR determination using one-compartment plasma clearance models and iohexol as the exogenous filtration marker. Iohexol was selected as it is non-radio labeled, inexpensive, widely available, and can be assayed at a central laboratory. Other commonly used non-radio labeled tracers have been (inulin) or are soon to be (iothalamate) discontinued. A plasma clearance model was selected as it requires no timed urine collections. A one-compartment model was preferred to a two compartment model as it requires fewer samples. The resulting recommendations were based on published evidence complemented by expert opinion.

Results
Recommendations include practical advice for patients and health professionals, preparation, administration and safety aspects of iohexol, laboratory analysis, blood sample collection and sample timing for both multiple and single sample protocols, description of the mGFR mathematical calculations as well as implementation strategies (Fig.). EKFC will provide materials such as patient information sheets, standard operating procedures, a study protocol template, and support for mGFR calculation.

Conclusion
Members of the EKFC have evaluated the evidence and formulated recommendations that include all aspects of iohexol plasma clearance measurement using a one compartment model.
*Author list on behalf of the European Kidney Function Consortium (EKFC).