Urinary Clearance Research Articles

A physiologically based toxicokinetic model for microplastics and nanoplastics in mice after oral exposure and its implications for human dietary exposure assessment

Evidence of microplastics (MPs) and nanoplastics (NPs) in foods and daily-use products, along with their frequent detection in the human body, has raised concerns regarding their potential impact on human health through dietary ingestion. However, there is a lack of quantitative tools to simulate their bioaccumulation and tissue distribution following environmental exposure. To address this gap, we developed the first physiologically based toxicokinetic (PBTK) model for predicting the biodistribution of MPs and NPs in mice following oral exposure under various exposure scenarios. This novel model incorporated key kinetic mass transport processes, such as membrane permeability, albumin binding, and cellular uptake. We identified that the absorption rate in the gastrointestinal tract and fecal excretion rate constant had significant impacts on organ dosimetry. Our regression analysis indicated that the size-dependent dissociation constant and urine clearance rate constant sharply increased by a factor of 3 as NPs particle size increased to 1µm. Finally, we developed a graphical user interface to enable interactive visualization and analysis for future applications, supporting human dietary exposure and risk assessment using available food consumption data and MPs/NPs residue data. The simulation results offer a mechanistic perspective, enhancing understanding of the internal organ dosimetry burden and health impacts from dietary exposure to MPs and NPs.

Kinetic analysis of D-Alanine upon oral intake in humans

D-Alanine, a rare enantiomer of alanine, can potentially alleviate the worsening of viral infections and maintain circadian rhythm. This study aimed to analyze the kinetics of D-Alanine upon oral intake. Five healthy volunteers were administered D-Alanine as a single oral dose at 11,236 or 33,708 µmoL (1–3 g). Upon intake of the lower dose, the plasma level of D-Alanine reached its peak concentration of 588.4 ± 40.9 µM with a peak time of 0.60 ± 0.06 h. The compartment model estimated the clearance of D-Alanine at 12.5 ± 0.3 L/h, or 208 ± 5 mL/min, distribution volume of 8.3 ± 0.7 L and half-life of 0.46 ± 0.04 h, suggesting a rapid clearance of D-Alanine. The peak concentration and area under the curve increased proportionally upon intake of the higher dose, while the clearance, distribution volume and half-life did not. The urinary ratio of D-Alanine per sum of D- and L-Alanine reached its peak of nearly 100%, followed by a slow decline. The peak time of the urinary ratio was 1.15 ± 0.15 h, showing a time lag of blood to urine excretion. Fractional excretion, a ratio of the clearance of a substance per a standard molecule in kidney, of D-Alanine increased from 14.0 ± 5.8% to 64.5 ± 10.3%; the latter corresponded to the urinary clearance of D-Alanine as about 77 mL/min for an adult, with a peak time of 1.90 ± 0.56 h. D-Alanine was quickly absorbed and appeared in blood, followed by urinary excretion. This kinetic analysis increases our fundamental knowledge of the oral intake of D-Alanine for the chronic dosing.Trial number: #UMIN000050865.Date of registration: 2023/6/30.

7761 Unmasking The Uncommon: A Case Of Primary Adrenal Insufficiency Presenting As Severe Hypercalcemia

Abstract Disclosure: A. Misbah: None. Z. Al-Hiti: None. A. Saleh: None. M. Joda: None. K. Rajamani: None. Adrenal insufficiency is a recognized but uncommon cause of hypercalcemia. The exact mechanism remains unknown; however, it is thought to be a combination of the hypovolemic state in adrenal insufficiency leading to decreased urinary clearance, as well as increased bone resorption. We present a case of primary adrenal insufficiency presenting with severe hypercalcemia. A 41 year old female with a past medical history of osteopenia, recently diagnosed postural orthostatic tachycardia syndrome (POTS), and hyponatremia attributed to SIADH presented with complaints of weakness and poor oral intake. She also reported a history of nausea, vomiting, weight loss, fatigue, and dizziness, for the last few months. She reported feeling well prior to a COVID-19 infection a few months back. At presentation, she was hypotensive with a blood pressure of 70/50 mmHg, while her other vital signs were stable. She appeared ill, and was noted to have dry oral mucous membranes. There was no increased pigmentation noted on exam. Initial laboratory evaluation revealed sodium of 130 (135-145 mmol/L), potassium of 5.3 (3.5-5.1 mmol/L), and creatinine of 1.7 (0.5-0.8 mg/dL). She had severe hypercalcemia with a calcium level of 15.5 (8.3-10.6 mg/dL) and had a blood glucose level of 53 (70-100 mg/dL). Venous blood gas indicated metabolic acidosis. Morning cortisol was low at 1 (3-23 ug/dL). Serum ACTH was elevated at 775 (0-46 pg/mL). Cosyntropin stimulation test confirmed primary adrenal insufficiency. She underwent work-up for hypercalcemia, which revealed a suppressed PTH, normal levels of PTHrP, vitamin D, and vitamin A. Serum and urine protein electrophoresis was normal. She was initially managed in the ICU and received aggressive fluid resuscitation. She was started on stress dose of hydrocortisone, which was then tapered to physiological doses of oral hydrocortisone and fludrocortisone. Subsequent improvements were observed in blood pressure, laboratory abnormalities, and normalized serum calcium levels. She was discharged home on hydrocortisone and fludrocortisone. On follow-up, she was doing well with the resolution of her symptoms. This case highlights the importance of recognizing adrenal insufficiency as one of the causes of hypercalcemia. Although hypercalcemia as a consequence of adrenal insufficiency is well-documented, the exact prevalence is not known but is estimated to be around 6%. After excluding more common diseases such as primary hyperparathyroidism and malignancy, the possibility of adrenal insufficiency should be considered as a cause of hypercalcemia. Treatment involves hormone replacement as well as hydration, bringing resolution to symptoms. Her presentation was unique, also due to the fact that her initial symptoms were diagnosed as POTS as well as SIADH. Given the onset of symptoms after a COVID-19 infection a few months ago, there could also be a potential link between the two. Presentation: 6/3/2024

Annual change in eGFR in renal hypouricemia: a retrospective pilot study.

Extremely low uric acid (UA) levels or increased urinary UA (Uua) excretion might be risk factors for kidney disease in renal hypouricemia (RHU) patients, but their relationship with kidney dysfunction is unclear. This study investigated time-dependent changes in eGFR in RHU patients. This multicenter retrospective study assessed UA metabolism and changes in eGFR (median 5.5years) in 13 RHU patients. We then compared eGFR change in 7 of 13 RHU patients whose eGFR could be measured for 4years with those in normouricemic group (n = 31). In addition, 7 RHU patients were divided into two groups based on URAT1 gene mutations: homozygote and compound heterozygote mutations (Homo/Com group, n = 3), and wild-type and heterogeneous mutations (WT/Hetero group, n = 4). In 13 RHU patients, the median and mean serum UA (SUA) were 0.8 (0.4-2.5) and 1.1 ± 0.7mg/dL. The median and mean Uua were 44.3 (12.7-141.1) and 49.7 ± 36.2mg/dL. The median and mean urinary urate clearance (Cua/Ccr) were 46.8 (11.3-73.6) and 43.3 ± 19.7%. Over 4years, eGFR did not change in the RHU group but declined in the normouricemic group. Annual mean eGFR decline and change rate in the RHU group were the same as those in the normouricemic group (- 1.09 ± 1.11 vs. - 1.09 ± 1.92mL/min/1.73 m2/year, p = 0.996) (- 1.74 ± 1.96 vs. - 1.36 ± 2.10%, p = 0.664). And no significant difference was found in eGFR decline or change rate between Homo/Com and WT/Hetero groups (- 0.33 ± 1.03 vs. - 1.67 ± 0.85mL/min/1.73 m2/year, p = 0.116) (- 0.61 ± 1.62 vs. - 2.59 ± 1.91%, p = 0.210). RHU from URAT1 genetic mutation may not show eGFR decline over 4 consecutive years.

Urinary Clearances of Indoxyl Sulfate and P-cresol Are Directly Correlated with the Functional Stress Response of the Proximal Tubule

Urinary Clearances of Indoxyl Sulfate and P-cresol Are Directly Correlated with the Functional Stress Response of the Proximal Tubule

Estimation of renal function immediately after cessation of continuous renal replacement therapy at the ICU

Estimating glomerular filtration (eGFR) after Continuous Renal Replacement Therapy (CRRT) is important to guide drug dosing and to assess the need to re-initiate CRRT. Standard eGFR equations cannot be applied as these patients neither have steady-state serum creatinine concentration nor average muscle mass. In this study we evaluate the combination of dynamic renal function with CT-scan based correction for aberrant muscle mass to estimate renal function immediately after CRRT cessation. We prospectively included 31 patients admitted to an academic intensive care unit (ICU) with a total of 37 CRRT cessations and measured serum creatinine before cessation (T1), directly (T2) and 5 h (T3) after cessation and the following two days when eGFR stabilized (T4, T5). We used the dynamic creatinine clearance calculation (D3C) equation to calculate eGFR (D3CGFR) and creatinine clearance (D3Ccreat) between T2-T3. D3Ccreat was corrected for aberrant muscle mass when a CT-scan was available using the CRAFT equation. We compared D3CGFR to stabilized CKD-EPI at T5 and D3CCreat to 4-h urinary creatinine clearance (4-h uCrCl) between T2-T3. We retrospectively validated these results in a larger retrospective cohort (NICE database; 1856 patients, 2064 cessations). The D3CGFR was comparable to observed stabilized CKD-EPI at T5 in the prospective cohort (MPE = − 1.6 ml/min/1.73 m2, p30 = 76%) and in the retrospective NICE-database (MPE = 3.2 ml/min/1.73 m2, p30 = 80%). In the prospective cohort, the D3CCreat had poor accuracy compared to 4-h uCrCl (MPE = 17 ml/min/1.73 m2, p30 = 24%). In a subset of patients (n = 13) where CT-scans were available, combination of CRAFT and D3CCreat improved bias and accuracy (MPE = 8 ml/min/1.73 m2, RMSE = 18 ml/min/1.73 m2) versus D3CCreat alone (MPE = 18 ml/min/1.73 m2, RMSE = 32 ml/min/1.73 m2). The D3CGFR improves assessment of eGFR in ICU patients immediately after CRRT cessation. Although the D3CCreat had poor association with underlying creatinine clearance, inclusion of CT derived biometric parameters in the dynamic renal function algorithm further improved the performance, stressing the role of muscle mass integration into renal function equations in critically ill patients.

SS-31 protects diabetic nephropathy progression: A systematic review of in vivo and in vitro studies

Context: Diabetic nephropathy is the leading cause of end-stage renal disease and also death in the world. Administration of Szeto-Schiller-31 (SS-31) as a potential therapeutic candidate that can decrease the renal function damage progressivity in diabetes needs to be comprehensively analyzed. Aims: To assess the protective effects of SS31 against the progressivity of diabetic nephropathy. Methods: This systematic review follows PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis) guidelines 2020. Searches of databases (Pubmed, Science Direct, Scopus, ProQuest, and Springer) were done on 17 September 2023 in order to find articles related to the animal diabetic model and SS-31 treatment. Manual searches from medRxiv were also conducted to obtain additional evidence. Renal function, histopathology analysis, reactive oxygen species in vivo, and in vitro analysis were described. Results: There were six in vivo studies, each of which discussed the renal function, histopathology, and reactive oxygen species (ROS), and four in vitro studies that discussed ROS. The available data suggested that SS-31 improves kidney function by lowering urinary albumin excretion, proteinuria, serum creatinine, creatinine clearance, and BUN, supported by histopathological improvements. In addition, SS-31 also has the effect of lowering 8-hydroxy-2-deoxyguanosine (8-OHdG) level, malondialdehyde (MDA) level, and nicotinamide adenine dinucleotide phosphate (NADPH) expression. Conclusions: SS31 had a renoprotective effect that could prevent the worsening of renal function in diabetic mice. In addition, the results of histopathology and ROS analysis also support the positive results of SS-31 treatment. Further studies are required to confirm its findings.

240.3: Post-kidney transplant (KTx) with primary allograft function, comparison of Serum creatinine with Serum Cystatin-C, and measured urinary creatinine clearance (mCrCl) with MDRD-4 eGFR and MDRD-4 eGFR eGFRCysC.

240.3: Post-kidney transplant (KTx) with primary allograft function, comparison of Serum creatinine with Serum Cystatin-C, and measured urinary creatinine clearance (mCrCl) with MDRD-4 eGFR and MDRD-4 eGFR eGFRCysC.

Theragnostic Gadolinium-Based Nanoparticles Safely Augment X-ray Radiation Effects in Patients with Cervical Cancer.

Activated guided irradiation by X-ray (AGuIX) nanoparticles are gadolinium-based agents that have the dual benefit of mimicking the effects of a magnetic resonance imaging (MRI) contrast agent used in a clinical routine and enhancing the radiotherapeutic activity of conventional X-rays (for cancer treatment). This "theragnostic" action is explained on the one hand by the paramagnetic properties of gadolinium and on the other hand by the generation of high densities of secondary radiation following the interaction of ionizing radiation and high-Z atoms, which leads to enhanced radiation dose deposits within the tumors where the nanoparticles accumulate. Here, we report the results of a phase I trial that aimed to assess the safety and determine the optimal dose of AGuIX nanoparticles in combination with chemoradiation and brachytherapy in patients with locally advanced cervical cancer. AGuIX nanoparticles were administered intravenously and appropriately accumulated within tumors on a dose-dependent manner, as assessed by T1-weighted MRI, with a rapid urinary clearance of uncaught nanoparticles. We show that the observed tumor accumulation of the compounds can support precise delineation of functional target volumes at the time of brachytherapy based on gadolinium enhancement. AGuIX nanoparticles combined with chemoradiation appeared well tolerated among the 12 patients treated, with no dose-limiting toxicity observed. Treatment yielded excellent local control, with all patients achieving complete remission of the primary tumor. One patient had a distant tumor recurrence. These results demonstrate the clinical feasibility of using theranostic nanoparticles to augment the accuracy of MRI-based treatments while focally enhancing the radiation activity in tumors.

The physiological basis of renal nuclear medicine.

Renal physiology underpins renal nuclear medicine, both academic and clinical. Clearance, an important concept in renal physiology, comprises tissue uptake rate of tracer (tissue clearance), disappearance rate from plasma (plasma clearance), appearance rate in urine (urinary clearance) and disappearance rate from tissue. In clinical research, steady-state plasma clearances of para-amino-hippurate and inulin have been widely used to measure renal blood flow (RBF) and glomerular filtration rate (GFR), respectively. Routinely, GFR is measured at non-steady state as plasma clearance of a filtration agent, such as technetium-99m diethylenetriaminepentaacetic acid. Scaled to three-dimensional whole body metrics rather than body surface area, GFR in women is higher than in men but declines faster with age. Age-related decline is predominantly from nephron loss. Tubular function determines parenchymal transit time, which is important in renography, and the route of uptake of technetium-99m dimercaptosuccinic acid, which is via filtration. Resistance to flow is defined according to the pressure-flow relationship but in renography, only transit time can be measured, which, being equal to urine flow divided by collecting system volume, introduces further uncertainty because the volume is also unmeasurable. Tubuloglomerular feedback governs RBF and GFR, is regulated by the macula densa, mediated by adenosine and renin, and can be manipulated with proximal tubular sodium-glucose cotransporter-2 inhibitors. Other determinants of renal haemodynamics include prostaglandins, nitric oxide and dopamine, while protein meal and amino acid infusion are used to measure renal functional reserve. In conclusion, for measuring renal responses to exogenous agents, steady-state para-amino-hippurate and inulin clearances should be replaced with rubidium-82 and gallium-68 EDTA for measuring RBF and GFR.

Association of urinary excretion rates of uric acid with biomarkers of kidney injury in patients with advanced chronic kidney disease.

The potential influence of hyperuricemia on the genesis and progression of chronic kidney disease (CKD) remains controversial. In general, the correlation between blood levels of uric acid (UA) and the rate of progression of CKD is considered to be modest, if any, and the results of relevant trials oriented to disclose the effect of urate-lowering therapies on this outcome have been disappointing. Urinary excretion rates of UA could reflect more accurately the potential consequences of urate-related kidney injury. Using a cross-sectional design, we investigated the correlation between different estimators of the rates of urinary excretion of UA (total 24-hour excretion, mean urinary concentration, renal clearance and fractional excretion)(main study variables), on one side, and urinary levels of selected biomarkers of kidney injury and CKD progression (DKK3, KIM1, NGAL, interleukin 1b and MCP)(main outcome variables), in 120 patients with advanced CKD (mean glomerular filtration rate 21.5 mL/minute). We took into consideration essential demographic, clinical and analytic variables with a potential confounding effect on the explored correlations (control variables). Spearman's rho correlation and nonlinear generalized additive regression models (GAM) with p-splines smoothers were used for statistical analysis. Multivariate analysis disclosed independent correlations between urinary UA concentrations, clearances and fractional excretion rates (but not plasma UA or total 24-hour excretion rates of UA), on one side, and the scrutinized markers. These correlations were more consistent for DKK3 and NGAL than for the other biomarkers. Glomerular filtration rate, proteinuria and treatment with statins or RAA axis antagonists were other independent correlates of the main outcome variables. Our results support the hypothesis that urinary excretion rates of UA may represent a more accurate marker of UA-related kidney injury than plasma levels of this metabolite, in patients with advanced stages of CKD. Further, longitudinal studies will be necessary, to disclose the clinical significance of these findings.

Recommendations for the assessment of glomerular filtration rate in patients with cancer: A position statement and systematic review on behalf of the American Society of Onco-Nephrology (ASON).

e24143 Background: Accurate assessment of glomerular filtration rate (GFR) is crucial to guiding drug eligibility, dose-adjusting systemic therapy, and minimizing the risks of both undertreatment and toxicity in patients with cancer. To date, there has been a lack of guidance to standardize approaches to GFR estimation in the cancer population based on the available evidence. We aim to present data on the first systematic review (SR) of GFR estimating equations in patients with cancer. Methods: We conducted a SR on behalf of the American Society of Onco-Nephrology (ASON) on the accuracy of equations to estimate GFR in adult patients with cancer, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We required that studies use a reference methodology as comparator involving measured GFR via urinary or plasma clearance of an exogenous filtration marker or carboplatin. Two search strategies focusing on studies using serum creatinine (Cr) and cystatin C (Cys) were developed. Risk of bias and quality assessment was performed for all studies. Results: A total of 39 studies (21,949 patients in total, 19,025 with solid cancers) were included. Studies assessing populations in Europe were most frequent (50%), followed by Asia (27%) and the remaining from Australia/New Zealand and North and South America. Risk of bias and quality assessment allocated 15 studies (38%) as low or very low quality, and 24 (62%) as low-moderate or moderate quality. The most commonly assessed GFR estimating equations included Cockroft-Gault (32 studies), Modification of Diet Renal Disease (MDRD) (24 studies), Chronic Kidney Disese Epidemiology Collaboration Study (CKD-EPI)Cr (22 studies), Wright (13 studies), CKD-EPICys (8 studies), CKD-EPICr-Cys (8 studies), and Jeliffe (8 studies). Given the importance of accurate and timely eGFR assessment and the evidence supporting the performance (i.e., accuracy) of the CKD-EPI incorporating both Cr and Cys, we suggest the use of this equation in patients with cancer (grade 2C). Where Cys is unavailable, CKD-EPICr is the next preferred equation given the supporting data for its performance and widespread availability. Since included studies were moderate quality or lower, the ASON rated the certainty of evidence as low. Also, additional data on clinical outcomes related to the selection of eGFR equations is needed. We suggest measurement of GFR via an exogenous filtration marker in patients with cancer for whom eGFR results in borderline eligibility for therapies or clinical trials (ungraded). Conclusions: Based on the results of this SR, we suggest use of contemporary methods for estimation of GFR (CKD-EPICr-Cys and CKD-EPICr-Cr) and avoidance of older and less accurate formulae such as Cockcroft-Gault.

#546 Decline of kidney function before and after start of peritoneal dialysis (PD)

Abstract Background and Aims Residual kidney function (RKF) is a key component for PD adequacy and associated with improved volume status, nutrition and quality of life as well as with increased survival. The aim of the present study was to compare decline of kidney function before and after start of PD. Method We studied patients starting PD (during 2000-2019) in an ongoing prospective study of patients starting dialysis. Study inclusion in almost all PD patients coincided with PD catheter insertion. Patients were included in the present analysis if they had at least one urinary collection before, and one after PD initiation (a), PD initiation less than six months after study inclusion (b) and > 6 months PD treatment (c). P-creatinine to calculate eGFR was retrospectively collected for 12 months before start of PD. During a large part of the study period, it was a clinical routine to collect 24-hour urine collections regularly in CKD5 patients, and these data were retrieved when available. After start of PD, regular 24-hour urine collections were part of the clinical routine to follow up and were retrieved for up to 12 months after PD start. eGFR was measured using the CKD-epi 2021 equation and GFR was calculated as the average of urinary creatinine and urea clearance corrected for BSA. The decline of eGFR before start of PD, the decline of GFR from 24-hour urine collections and the decline of GFR after start of PD were compared to each other. Results We studied 138 patients starting PD. The mean age was 55 ± SD13 years, and there were 80 males and 58 females. The mean blood pressure was 153 ± SD21/89 ± SD11 mmHg and BMI was 25 ± SD4 kg/m2. The etiologies of end stage kidney disease were nephrosclerosis 17%, diabetic nephropathy 22%, glomerulonephritis 25%, polycystic kidney disease 14% and other 22%. The GFR at PD start was 8.5 ± SD 2.3 mL/min/1,73 m² and eGFR was 5.8 ± SD 1.9 mL/min/1,73 m². The results show a significantly slower kidney function decline rate after start of PD, with an average of −0.59 mL/min/1,73 m²/month before PD initiation compared to −0.34 mL/min/1,73 m²/month after. Conclusion Decline of GFR was slower after start of PD suggesting that earlier initiation of dialysis may be beneficial for the preservation of RKF. Notably, there was a marked attenuation after 3 months of dialysis. Furthermore, the decline rate of GFR before PD start was similar using eGFR or GFR from 24-h urine collection, though for eGFR at somewhat lower levels. However, there were pronounced differences between those two methods in individual patients demonstrating that eGFR is unreliable with very low GFR. Further study will be performed to analyze what factors that are associated with better preservation of RKF.

Delivery of Mesenchymal Stem Cells during Hypothermic Machine Perfusion in a Translational Kidney Perfusion Study.

In transplantation, hypothermic machine perfusion (HMP) has been shown to be superior to static cold storage (SCS) in terms of functional outcomes. Ex vivo machine perfusion offers the possibility to deliver drugs or other active substances, such as Mesenchymal Stem Cells (MSCs), directly into an organ without affecting the recipient. MSCs are multipotent, self-renewing cells with tissue-repair capacities, and their application to ameliorate ischemia- reperfusion injury (IRI) is being investigated in several preclinical and clinical studies. The aim of this study was to introduce MSCs into a translational model of hypothermic machine perfusion and to test the efficiency and feasibility of this method. Methods: three rodent kidneys, six porcine kidneys and three human kidneys underwent HMP with 1-5 × 106 labelled MSCs within respective perfusates. Only porcine kidneys were compared to a control group of 6 kidneys undergoing HMP without MSCs, followed by mimicked reperfusion with whole blood at 37 °C for 2 h for all 12 kidneys. Reperfusion perfusate samples were analyzed for levels of NGAL and IL-β by ELISA. Functional parameters, including urinary output, oxygen consumption and creatinine clearance, were compared and found to be similar between the MSC treatment group and the control group in the porcine model. IL-1β levels were higher in perfusate and urine samples in the MSC group, with a median of 285.3 ng/mL (IQR 224.3-407.8 ng/mL) vs. 209.2 ng/mL (IQR 174.9-220.1), p = 0.51 and 105.3 ng/mL (IQR 71.03-164.7 ng/mL) vs. 307.7 ng/mL (IQR 190.9-349.6 ng/mL), p = 0.16, respectively. MSCs could be traced within the kidneys in all models using widefield microscopy after HMP. The application of Mesenchymal Stem Cells in an ex vivo hypothermic machine perfusion setting is feasible, and MSCs can be delivered into the kidney grafts during HMP. Functional parameters during mimicked reperfusion were not altered in treated kidney grafts. Changes in levels of IL-1β suggest that MSCs might have an effect on the kidney grafts, and whether this leads to a positive or a negative outcome on IRI in transplantation needs to be determined in further experiments.

Accuracy of eGFR Equation for Predicting Glomeruloar Filtration Rate in Potential Living Kidney Donor

This Descriptive Cross-Sectional Study, involving 201 patients, conducted at Sindh Institute of Urology and Transplantation (SIUT) Karachi, Pakistan after approval from institute research board. The estimated Glomerular Filtration Rate (eGFR) was calculated using the appropriate equation. Participants were instructed to collect their urine over a 24-hour period in a container devoid of any additives or preservatives. The collected urine specimens were subsequently sent to the institutional laboratory for analysis, with GFR determined based on 24-hour urine creatinine clearance to ensure accuracy. All data collected during the study period were meticulously entered into a predefined proforma, which was then electronically stored and utilized for research purposes.
 Results: Mean ± SD of age was 33.30±9.12 years. Out of 201 patients, 124 (61.7%) were male while 77 (38.3%) were female. In distribution of accuracy of eGFR by CKD-EPI equation, accuracy of (Cr-Cys) equation was noted as 60 (29.9%), (Cys) as 47 (23.4%) while accuracy of CKD- EPI (PK) equation was documented as 96 (47.8%).
 Conclusion: It is to be concluded that accuracy of CKD-EPI is closer to 24 -h urinary creatinine clearance in the calculation of eGFR. However, none of the eGFR formulas can be used in renal transplant donors because of their low accuracy, and 24-h urine creatinine clearance should be used for evaluation of the GFR in this population.

Discrepancies between transcutaneous and estimated glomerular filtration rates in rats with chronic kidney disease

Accurate assessment of the glomerular filtration rate (GFR) is crucial for researching kidney disease in rats. Although validation of methods that assess GFR is crucial, large-scale comparisons between different methods are lacking. Both transcutaneous GFR (tGFR) and a newly developed estimated GFR (eGFR) equation by our group provide a low-invasive approach enabling repeated measurements. The tGFR is a single bolus method using FITC-labeled sinistrin to measure GFR based on half-life of the transcutaneous signal, whilst the eGFR is based on urinary sinistrin clearance. Here, we retrospectively compared tGFR, using both 1- and 3- compartment models (tGFR_1c and tGFR_3c, respectively) to the eGFR in a historic cohort of 43 healthy male rats and 84 male rats with various models of chronic kidney disease. The eGFR was on average considerably lower than tGFR-1c and tGFR-3c (mean differences 855 and 216 μL/min, respectively) and only 20 and 47% of measurements were within 30% of each other, respectively. The relative difference between eGFR and tGFR was highest in rats with the lowest GFR. Possible explanations for the divergence are problems inherent to tGFR, such as technical issues with signal measurement, description of the signal kinetics, and translation of half-life to tGFR, which depends on distribution volume. The unknown impact of isoflurane anesthesia used in determining mGFR remains a limiting factor. Thus, our study shows that there is a severe disagreement between GFR measured by tGFR and eGFR, stressing the need for more rigorous validation of the tGFR and possible adjustments to the underlying technique.

Renal sinus fat is associated with intrarenal hemodynamic abnormalities independent of visceral fat in patients with chronic kidney disease

ObjectiveObesity is a risk factor of chronic kidney disease (CKD), contributing to the rising incidence of cardiometabolic diseases. Renal sinus fat (RSF) is an ectopic fat depot located at the renal cavity that could impair renal function and hemodynamic through compression of renal structures. The major purpose of this study was to explore the relationship between RSF accumulation and renal dysfunction in CKD patients. MethodsWe evaluated the associations between computed tomography measured RSF volume and key clinical and histologic parameters involved in renal function and hemodynamics in 132 well-characterized CKD patients who underwent renal biopsy (median age: 62 years; 63.6% men). ResultsRSF volume normalized by renal volume (RSF%) positively correlated with obesity-related traits such body mass index and visceral fat volume (VFV) (all P < 0.001) whereas it negatively correlated with estimated glomerular filtration rate (eGFR) (ρ = −0.42, P < 0.001) and 24-h urinary creatinine clearance (CCr) (ρ = −0.34, P < 0.001). Notably, we found robust positive correlations between RSF% and renal resistive index (RRI) measured by the Doppler ultrasound (ρ = 0.40, P < 0.001), and the histological severity of global glomerular sclerosis (ρ = 0.48, P < 0.001) and interstitial fibrosis and tubular atrophy (IFTA) (ρ = 0.35, P < 0.001). In the multivariate linear regression models, after accounting for potential confounders including VFV, RSF% remained significantly associated with CCr (β = −0.26, P < 0.001), RRI (β = 0.17, P = 0.022), global glomerular sclerosis (β = 0.21, P = 0.002), and IFTA (β = 0.17, P = 0.012). ConclusionRSF accumulation is associated with renal dysfunction and hemodynamic abnormalities independent of visceral adiposity. Our results suggest that RSF may have a potential unique role in the pathogenesis of CKD.

Topical Tacrolimus and Mycophenolic Acid Therapy Synergizes with Low Dose Systemic Immunosuppression to Sustain Vascularized Composite Allograft Survival

AimThe goal of this study was to evaluate whether topical administration of tacrolimus (TAC) and mycophenolic acid (MPA) at the transplant site enables vascularized composite allograft (VCA) survival with significant minimization of the dose and adverse effects of systemic TAC (STAC) immunosuppression. Materials and methodsLewis (Lew) rats received orthotopic hind limb allotransplants from fully mismatched Brown Norway (BN) donors. Group 1 (Controls) received no treatment. Other groups were treated with STAC at a dose of 1 mg/kg/day for 7 days. On post-operative day (POD) 8, the STAC dose was dropped to 0.1 mg/kg/day for Group 2 and maintained at 1 mg/kg for Group 3. Group 4 received topical application of TAC and MPA on the transplanted (Tx) limb starting POD 8 without STAC. Group 5 received topical TAC and MPA on the contralateral non-Tx limb and Group 6 received topical TAC and MPA on the Tx limb starting POD 8 along with low dose STAC (0.1 mg/kg/day). Treatment was continued until the study end point was reached, defined as either grade 3 rejection or allograft survival exceeding 100 days. .We conducted sequential LC-MS/MS measurements to assess TAC and MPA concentrations in both blood/plasma and allograft tissues. Additionally, we evaluated markers indicative of organ toxicity associated with STAC immunosuppression. ResultsCompared to controls, topical therapy with TAC+MPA significantly prolonged allograft survival beyond 100 daysat very low dose STAC (0.1 mg/kg/day) (Group 6). The histopathological assessment of the grafts was consistent with the clinical outcomes. .Drug levels in blood/plasma remained low or undetectable, while allograft tissues showed higher drug concentrations compared to contralateral limb tissues (P<0.05). . Urinary creatinine clearance remained within the normal range at 2.5 mL/min. ConclusionCombination therapy with topical TAC and MPA synergizes with a very low dose, corticosteroid- free-STAC regimen and facilitates rejection-free, prolonged VCA survival without morbidity.

Solução intravenosa poliiônica com concentração elevada de lactato (84 mEq/L) é eficaz para o tratamento de bezerros com diarreia

ABSTRACT This study aimed to evaluate the effectiveness of an electrolyte solution with a high lactate concentration (84mEq/L; L84) in correcting imbalances in diarrheal calves. Another solution with similar electrolyte composition, containing 84mEq/L of bicarbonate (B84) was used for comparison. Diarrhea was induced in neonatal calves by rotavirus infection, sucrose ingestion and furosemide administration. When a moderate degree of metabolic acidosis was reached, the calves were treated with intravenous infusion of L84 (n=10) or B84 (n=10) solutions. Venous blood and urine samples were collected before starting the infusion (0 h), in the middle (2.5 h), at the end (5.0 h) and 2.5 hours later. Total plasma protein concentration, blood and urine pH, blood pCO2, HCO3 -, and BE, plasma and urine concentration of L-lactate, and serum and urine concentrations of Na+, K+, and Cl- were measured. Strong ion difference, total concentration of non-volatile weak acids, anion gap, strong ion gap, percentage change in plasma volume, and urinary fractional clearances of Na+, K+, Cl-, and L-lactate were calculated. The calves demonstrated moderate dehydration, hypernatremia, hyperchloremia, metabolic acidosis, and unmeasured anion accumulation. These changes were completely corrected with the L84 solution, and the effects did not differ from those observed with B84 solution. The calves recovered without further therapeutic procedures, demonstrating that the L84 solution was effective for treating diarrheal calves.

Muscle-Derived Stem/Progenitor Cells Ameliorate Acute Kidney Injury in Rats through the Anti-Apoptotic Pathway and Demonstrate Comparable Effects to Bone Marrow Mesenchymal Stem Cells.

Background and Objectives: To date, the therapeutic potential of skeletal muscle-derived stem/progenitor cells (MDSPCs) for acute kidney injury (AKI) has only been evaluated by our research group. We aimed to compare MDSPCs with bone marrow mesenchymal stem cells (BM-MSCs) and evaluate their feasibility for the treatment of AKI. Materials and Methods: Rats were randomly assigned to four study groups: control, GM (gentamicin) group, GM+MDSPCs, and GM+BM-MSCs. AKI was induced by gentamicin (80 mg/kg/day; i.p.) for 7 consecutive days. MDSPCs and BM-MSCs were injected 24 h after the last gentamicin injection. Kidney parameters were determined on days 0, 8, 14, 21, and 35. Results: MDSPCs and BM-MSCs accelerated functional kidney recovery, as reflected by significantly lower serum creatinine levels and renal injury score, higher urinary creatinine and creatinine clearance levels (p < 0.05), lower TUNEL-positive cell number, and decreased KIM-1 and NGAL secretion in comparison to the non-treated AKI group. There was no significant difference in any parameters between the MDSPCs and BM-MSCs groups (p > 0.05). Conclusions: MDSPCs and BM-MSCs can migrate and incorporate into injured renal tissue, resulting in a beneficial impact on functional and morphological kidney recovery, which is likely mediated by the secretion of paracrine factors and an anti-apoptotic effect. MDSPCs were found to be non-inferior to BM-MSCs and therefore can be considered as a potential candidate strategy for the treatment of AKI.