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Calvert ND, Kirby A, Suchý M, Pallister P, Torrens AA, Burger D, Melkus G, Schieda N, Shuhendler AJ. Direct mapping of kidney function by DCE-MRI urography using a tetrazinanone organic radical contrast agent. Nat Commun 2023; 14:3965. [PMID: 37407664 DOI: 10.1038/s41467-023-39720-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 06/27/2023] [Indexed: 07/07/2023] Open
Abstract
Chronic kidney disease (CKD) and acute kidney injury (AKI) are ongoing global health burdens. Glomerular filtration rate (GFR) is the gold standard measure of kidney function, with clinical estimates providing a global assessment of kidney health without spatial information of kidney- or region-specific dysfunction. The addition of dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) to the anatomical imaging already performed would yield a 'one-stop-shop' for renal assessment in cases of suspected AKI and CKD. Towards urography by DCE-MRI, we evaluated a class of nitrogen-centered organic radicals known as verdazyls, which are extremely stable even in highly reducing environments. A glucose-modified verdazyl, glucoverdazyl, provided contrast limited to kidney and bladder, affording functional kidney evaluation in mouse models of unilateral ureteral obstruction (UUO) and folic acid-induced nephropathy (FAN). Imaging outcomes correlated with histology and hematology assessing kidney dysfunction, and glucoverdazyl clearance rates were found to be a reliable surrogate measure of GFR.
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Affiliation(s)
- Nicholas D Calvert
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, 150 Louis Pasteur Pvt., Ottawa, Ontario, K1N 6N5, Canada
| | - Alexia Kirby
- Department of Biology, University of Ottawa, 150 Louis Pasteur Pvt., Ottawa, Ontario, K1N 6N5, Canada
| | - Mojmír Suchý
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, 150 Louis Pasteur Pvt., Ottawa, Ontario, K1N 6N5, Canada
| | - Peter Pallister
- Department of Chemistry, Carleton University, 1125 Colonel By Dr., Ottawa, Ontario, K1S 5B6, Canada
| | - Aidan A Torrens
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, 150 Louis Pasteur Pvt., Ottawa, Ontario, K1N 6N5, Canada
| | - Dylan Burger
- Kidney Research Center, Ottawa Hospital Research Institute, University of Ottawa, 501 Smyth Rd, Ottawa, Ontario, K1H 8L6, Canada
| | - Gerd Melkus
- Dept. Medical Imaging, The Ottawa Hospital, 501 Smyth Rd, Ottawa, Ontario, K1H 8L6, Canada
- Dept. Radiology, University of Ottawa, 501 Smyth Rd, Ottawa, Ontario, K1H 8L6, Canada
| | - Nicola Schieda
- Dept. Radiology, University of Ottawa, 501 Smyth Rd, Ottawa, Ontario, K1H 8L6, Canada
| | - Adam J Shuhendler
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, 150 Louis Pasteur Pvt., Ottawa, Ontario, K1N 6N5, Canada.
- Department of Biology, University of Ottawa, 150 Louis Pasteur Pvt., Ottawa, Ontario, K1N 6N5, Canada.
- University of Ottawa Heart Institute, 40 Ruskin St., Ottawa, Ontario, K1Y 4W7, Canada.
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Jensen MS, de Araujo IBBA, Mutsaers HAM, Nørregaard R. Transcutaneous measurement of renal function in two rodent models of obstructive nephropathy. BMC Res Notes 2023; 16:119. [PMID: 37365638 DOI: 10.1186/s13104-023-06387-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 06/13/2023] [Indexed: 06/28/2023] Open
Abstract
OBJECTIVE Glomerular filtration rate (GFR) is a key indicator of renal function. In both clinical practice and pre-clinical research, serum levels of endogenous filtration markers, such as creatinine, are often used to estimate GFR. However, these markers often do not reflect minor changes in renal function. In this study, we therefore set out to evaluate the applicability of transcutaneous GFR (tGFR) measurements to monitor the changes in renal function, as compared to plasma creatinine (pCreatinine), in two models of obstructive nephropathy, namely unilateral ureteral obstruction (UUO) or bilateral ureteral obstruction followed by release (BUO-R) in male Wistar rats. RESULTS UUO animals showed a significant reduction in tGFR compared to baseline; whereas pCreatinine levels were not significantly changed. In BUO animals, tGFR drops 24 h post BUO and remains lower upon release of the obstruction until day 11. Concomitantly, pCreatinine levels were also increased 24 h after obstruction and 24 h post release, however after 4 days, pCreatinine returned to baseline levels. In conclusion, this study revealed that the tGFR method is superior at detecting minor changes in renal function as compared to pCreatinine measurements.
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Affiliation(s)
- Michael Schou Jensen
- Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Boulevard 11, Aarhus N, DK-8200, Denmark
| | | | - Henricus A M Mutsaers
- Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Boulevard 11, Aarhus N, DK-8200, Denmark
| | - Rikke Nørregaard
- Department of Clinical Medicine, Aarhus University, Palle Juul-Jensens Boulevard 11, Aarhus N, DK-8200, Denmark.
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Raina M, Ashraf A, Soundararajan A, Mandal AK, Sethi SK. Pharmacokinetics in Critically Ill Children with Acute Kidney Injury. Paediatr Drugs 2023:10.1007/s40272-023-00572-z. [PMID: 37266815 DOI: 10.1007/s40272-023-00572-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/12/2023] [Indexed: 06/03/2023]
Abstract
Acute kidney injury (AKI) is a commonly encountered comorbidity in critically ill children. The coexistence of AKI disturbs drug pharmacokinetics and pharmacodynamics, leading to clinically significant consequences. This can complicate an already critical clinical scenario by causing potential underdosing or overdosing giving way to possible therapeutic failures and adverse reactions. Current available studies offer little guidance to help maneuver such complex dosing regimens and decision-making in pediatric patients as most of them are done on heterogeneous groups of adult populations. Though there are some studies on drug dosing during continuous renal replacement therapy (CRRT), their utility is in question because of the recent advances in CRRT technology. Our review aims to discuss the principles of pharmacokinetics pertinent for honing the existing practices of drug dosing in critically ill children with AKI, and the various complexities and intricate challenges involved. This in turn will provide a framework to help enable caretakers to tailor dosing regimens in complex clinical setups with further ease and precision.
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Affiliation(s)
| | - Amani Ashraf
- Northeast Ohio Medical University, Rootstown, OH, USA
| | - Anvitha Soundararajan
- Akron Nephrology Associates/Cleveland Clinic Akron General Medical Center, Akron, OH, USA
| | | | - Sidharth Kumar Sethi
- Pediatric Nephrology, Kidney Institute, Medanta, The Medicity Hospital, Gurgaon, Haryana, 122001, India.
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Abstract
Glomerular filtration rate (GFR) is considered the gold standard to test kidney function. However, the serial blood and/or urine sample collection required for the calculation of the GFR is stressful for the animal and time consuming for the experimenter. Here, we describe a transcutaneous assessment of renal function in conscious animals that does not require plasma or urine sampling and/or deep anesthesia. For the measurement, we use a near-infrared (NIR) device that records the excretion kinetic of the renal marker ABZWCY-HPβCD. ABZWCY-HPβCD is a new hydrophilic, stable, and nontoxic NIR fluorescent agent that can be used as a renal marker as it is filtrated and completely excreted through the kidneys into the urine without reabsorption or secretion and without accumulation in the skin. The data recorded in the device are then analyzed with "GFRmeasure," an open-source, freely downloadable, and user-friendly software.
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Molitoris BA. Rethinking CKD Evaluation: Should We Be Quantifying Basal or Stimulated GFR to Maximize Precision and Sensitivity? Am J Kidney Dis 2017; 69:675-683. [PMID: 28223001 PMCID: PMC5403623 DOI: 10.1053/j.ajkd.2016.11.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 11/14/2016] [Indexed: 12/20/2022]
Abstract
Chronic kidney disease (CKD) is an increasing clinical problem. Although clinical risk factors and biomarkers for the development and progression of CKD have been identified, there is no commercial surveillance technology to definitively diagnose and quantify the severity and progressive loss of glomerular filtration rate (GFR) in CKD. This has limited the study of potential therapies to late stages of CKD when FDA-registerable events are more likely. Because patient outcomes, including the rate of CKD progression, correlate with disease severity and effective therapy may require early intervention, being able to diagnose and stratify patients by their level of decreased kidney function early on is key for translational progress. In addition, renal reserve, defined as the increase in GFR following stimulation, may improve the quantification of GFR based solely on basal levels. Various groups are developing and characterizing optical measurement techniques using new minimally invasive or noninvasive approaches for quantifying basal and stimulated kidney function. This development has the potential to allow widespread individualization of therapy at an earlier disease stage. Therefore, the purposes of this review are to suggest why quantifying stimulated GFR, by activating renal reserve, may be advantageous in patients and to review fluorescent technologies to deliver patient-specific GFR.
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Affiliation(s)
- Bruce A Molitoris
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indiana Center for Biological Microscopy, Rouderbush VA, Indianapolis, IN.
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Molitoris BA, Reilly ES. Quantifying Glomerular Filtration Rates in Acute Kidney Injury: A Requirement for Translational Success. Semin Nephrol 2017; 36:31-41. [PMID: 27085733 DOI: 10.1016/j.semnephrol.2016.01.008] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Acute kidney injury (AKI) remains a vexing clinical problem that results in unacceptably high patient mortality, development of chronic kidney disease, and accelerated progression to end-stage kidney disease. Although clinical risks factors for developing AKI have been identified, there is no reasonable surveillance technique to definitively and rapidly diagnose and determine the extent of severity of AKI in any patient. Because patient outcomes correlate with the extent of injury, and effective therapy likely requires early intervention, the ability to rapidly diagnose and stratify patients by their level of kidney injury is paramount for translational progress. Many groups are developing and characterizing optical measurement techniques using novel minimally invasive or noninvasive techniques that can quantify kidney function independent of serum or urinary measurements. The use of both one- and two-compartment models, as well as continuous monitoring, are being developed. This review documents the need for glomerular filtration rate measurement in AKI patients and discusses the approaches being taken to deliver this overdue technique that is necessary to help propel nephrology to individualization of care and therapeutic success.
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Affiliation(s)
- Bruce A Molitoris
- Division of Nephrology, Department of Medicine, Indiana Center for Biological Microscopy, Indiana University School of Medicine, Roudebush VA, Indianapolis, Indiana; FAST BioMedical, Indianapolis, Indiana.
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Improved kinetic model for the transcutaneous measurement of glomerular filtration rate in experimental animals. Kidney Int 2016; 90:1377-1385. [PMID: 27665115 DOI: 10.1016/j.kint.2016.07.024] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 07/13/2016] [Accepted: 07/14/2016] [Indexed: 02/06/2023]
Abstract
Transcutaneous measurement of the glomerular filtration rate (tGFR) is now frequently used in animal studies. tGFR allows consecutive measurements on the same animal, including multiple measurements on a daily basis, because no blood sampling is required. Here we derive and validate a novel kinetic model for the description of transcutaneously measured FITC-Sinistrin excretion kinetics. In contrast to standard 1- to 3-compartment models, our model covers the complete kinetic, including injection and distribution of the tracer in the plasma compartment. Because the model describes the complete progression of the measurement, it allows further refinement by correcting for baseline shifts observed occasionally during measurement. Possible reasons for shifts in the background signal include photo bleaching of the skin, autofluorescence, changes of physiological state of the animals during the measurements, or effects arising from the attachment of the measurement device. Using the new 3-compartment kinetic model with modulated baseline (tGFR3cp.b.m), tGFR measurements in rats can reach comparable precision as those from GFR measurements assessed using a gold standard technique based on constant infusion of a tracer. Moreover, the variability of simultaneous (parallel) measurements, as well as repeated tGFR measurements in the same animals, showed higher precision when tGFR3cp.b.m was compared with the 1-compartment tGFR1cp model.
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