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2.
Clin Proteomics ; 20(1): 19, 2023 Apr 20.
Article in English | MEDLINE | ID: mdl-37076799

ABSTRACT

BACKGROUND: Halting progression of chronic kidney disease (CKD) to established end stage kidney disease is a major goal of global health research. The mechanism of CKD progression involves pro-inflammatory, pro-fibrotic, and vascular pathways, but pathophysiological differentiation is currently lacking. METHODS: Plasma samples of 414 non-dialysis CKD patients, 170 fast progressors (with ∂ eGFR-3 ml/min/1.73 m2/year or worse) and 244 stable patients (∂ eGFR of - 0.5 to + 1 ml/min/1.73 m2/year) with a broad range of kidney disease aetiologies, were obtained and interrogated for proteomic signals with SWATH-MS. We applied a machine learning approach to feature selection of proteins quantifiable in at least 20% of the samples, using the Boruta algorithm. Biological pathways enriched by these proteins were identified using ClueGo pathway analyses. RESULTS: The resulting digitised proteomic maps inclusive of 626 proteins were investigated in tandem with available clinical data to identify biomarkers of progression. The machine learning model using Boruta Feature Selection identified 25 biomarkers as being important to progression type classification (Area Under the Curve = 0.81, Accuracy = 0.72). Our functional enrichment analysis revealed associations with the complement cascade pathway, which is relevant to CKD as the kidney is particularly vulnerable to complement overactivation. This provides further evidence to target complement inhibition as a potential approach to modulating the progression of diabetic nephropathy. Proteins involved in the ubiquitin-proteasome pathway, a crucial protein degradation system, were also found to be significantly enriched. CONCLUSIONS: The in-depth proteomic characterisation of this large-scale CKD cohort is a step toward generating mechanism-based hypotheses that might lend themselves to future drug targeting. Candidate biomarkers will be validated in samples from selected patients in other large non-dialysis CKD cohorts using a targeted mass spectrometric analysis.

3.
Physiol Rep ; 10(5): e15211, 2022 03.
Article in English | MEDLINE | ID: mdl-35266337

ABSTRACT

BACKGROUND: Renal ischemia reperfusion injury (R-IRI) can cause acute kidney injury (AKI) and chronic kidney disease (CKD), resulting in significant morbidity and mortality. To understand the underlying mechanisms, reproducible small-animal models of AKI and CKD are needed. We describe how innovative technologies for measuring kidney function noninvasively in small rodents allow successful refinement of the R-IRI models, and offer the unique opportunity to monitor longitudinally in individual animals the transition from AKI to CKD. METHODS: Male BALB/c mice underwent bilateral renal pedicle clamping (AKI) or unilateral renal pedicle clamping with delayed contralateral nephrectomy (CKD) under isoflurane anesthetic. Transdermal GFR monitoring and multispectral optoacoustic tomography (MSOT) in combination with statistical analysis were used to identify and standardize variables within these models. RESULTS: Pre-clamping anesthetic time was one of the most important predictors of AKI severity after R-IRI. Standardizing pre-clamping time resulted in a more predictably severe AKI model. In the CKD model, MSOT demonstrated initial improvement in renal function, followed by significant progressive reduction in function between weeks 2 and 4. Performing contralateral nephrectomy on day 14 enabled the development of CKD with minimal mortality. CONCLUSIONS: Noninvasive monitoring of global and individual renal function after R-IRI is feasible and reproducible. These techniques can facilitate refinement of kidney injury models and enable the degree of injury seen in preclinical models to be translated to those seen in the clinical setting. Thus, future therapies can be tested in a clinically relevant, noninvasive manner.


Subject(s)
Acute Kidney Injury , Renal Insufficiency, Chronic , Reperfusion Injury , Acute Kidney Injury/diagnosis , Acute Kidney Injury/etiology , Animals , Disease Models, Animal , Kidney/physiology , Male , Mice , Mice, Inbred BALB C
4.
BMC Nephrol ; 23(1): 38, 2022 01 18.
Article in English | MEDLINE | ID: mdl-35042473

ABSTRACT

BACKGROUND: Chronic kidney disease (CKD) is an independent risk factor for stroke. Stroke is also an independent risk factor for worse CKD outcomes and inflammation may contribute to this bidirectional relationship. This study aims to investigate inflammatory biomarkers in patients with non-dialysis CKD (ND-CKD) with and without stroke. METHODS: A propensity matched sample from > 3000 Salford Kidney Study (SKS) patients, differentiated by previous stroke at study recruitment, had stored plasma analyzed for interleukin- 6 (IL-6), Von Willebrand Factor (VWF) and C-reactive protein (CRP). Multivariable cox regression analysis investigated associations between inflammation and death, end-stage renal disease (ESRD) and future non-fatal cardiovascular events (NFCVE). RESULTS: A total of 157 previous stroke patients were compared against 162 non-stroke patients. There were no significant differences in inflammatory biomarkers between the two groups. Previous stroke was associated with greater mortality risk, hazard ratio (HR) (95% CI) was 1.45 (1.07-1.97). Higher inflammatory biomarker concentrations were independently associated with death but not ESRD or NFCVE in the total population. For each 1 standard deviation (SD) increase in log IL-6, VWF and CRP, the HR for all-cause mortality were 1.35 (1.10-1.70), 1.26 (1.05-1.51) and 1.34 (1.12-1.61), respectively. CRP retained its independent association (HR 1.47 (1.15-1.87)) with death in the stroke population. CONCLUSION: Previous stroke is an important determinant of mortality. However, the adverse combination of stroke and ND-CKD does not seem to be driven by higher levels of inflammation detected after the stroke event. Biomarkers of inflammation were associated with worse outcome in both stroke and non-stroke ND-CKD patients. TRIAL REGISTRATION: 15/NW/0818 .


Subject(s)
C-Reactive Protein/analysis , Inflammation/blood , Inflammation/etiology , Interleukin-6/blood , Renal Insufficiency, Chronic/blood , Renal Insufficiency, Chronic/complications , Stroke/blood , Stroke/complications , von Willebrand Factor/analysis , Aged , Biomarkers/blood , Female , Humans , Male , Propensity Score
5.
Clin Kidney J ; 14(6): 1639-1648, 2021 Jun.
Article in English | MEDLINE | ID: mdl-34084459

ABSTRACT

BACKGROUND: Cognitive impairment in chronic kidney disease (CKD) is common and underrecognized [1, 2]. Determining risk factors for cognitive impairment and whether speed of CKD progression is an important consideration may help identify cognitive impairment by nephrologists. Vascular disease is thought to underpin cognitive impairment in CKD and by segregating CKD patients with proven vascular disease, we may also be able to discover other important associations with cognitive impairment in CKD patients. METHOD: A total of 250 patients in a UK prospective cohort of CKD patients underwent two cognitive assessments: Montreal Cognitive Assessment test and Trail Making Test. Cognitive impairment was defined using validated population cut-offs (cognitive impairment) and relative cognitive impairment. Relative cognitive impairment was defined by <1 standard deviation below the mean Z-score on any completed test. Two multivariable logistical regression models identified variables associated with cognitive impairment and realtive cognitive impairment. RESULTS: About 44 and 24.8% of patients suffered cognitive impairment and relative cognitive impairment, respectively. Depression, previous stroke and older age were significantly associated with cognitive impairment. Older age was significantly associated with relative cognitive impairment (P ≤ 0.05) and higher proteinuria and the use of psychodynamic medications were also significantly associated with relative cognitive impairment (P = 0.05). Delta estimated glomerular filtration rate (eGFR) in patients with cognitive impairment and relative cognitive impairment compared with those having normal cognition was similar (-0.77 versus -1.35 mL/min/1.73 m2/year, P = 0.34 for cognitive impairment and -1.12 versus -1.02 mL/min/1.73 m2/year, P = 0.89 for relative cognitive impairment). CONCLUSION: Risk factors for cognitive impairment in CKD include previous stroke, depression or anxiety, higher proteinuria and prescription of psychodynamic medications. Patients with a faster eGFR decline do not represent a group of patients at increased risk of cognitive impairment.

6.
Trials ; 21(1): 820, 2020 Sep 30.
Article in English | MEDLINE | ID: mdl-32998761

ABSTRACT

BACKGROUND: Cognitive impairment is common in haemodialysis (HD) patients and is associated independently with depression and mortality. This association is poorly understood, and no intervention is proven to slow cognitive decline. There is evidence that cooler dialysis fluid (dialysate) may slow white matter changes in the brain, but no study has investigated the effect of cooler dialysate on cognition. This study addresses whether cooler dialysate can prevent the decline in cognition and improve quality of life (QOL) in HD patients. METHODS: This is a multi-site prospective randomised, double-blinded feasibility trial. SETTING: Four HD units in the UK. PARTICIPANTS AND INTERVENTIONS: Ninety HD patients randomised (1:1) to standard care (dialysate temperature 36.5 °C) or intervention (dialysate temperature 35 °C) for 12 months. PRIMARY OUTCOME MEASURE: Change in cognition using the Montreal Cognitive Assessment (MoCA). SECONDARY OUTCOME MEASURES: Recruitment and attrition rates, reasons for non-recruitment, frequency of intradialytic hypotension, depressive symptom scores, patient and carers burden, a detailed computerised cognitive test and QOL assessments. ANALYSIS: mixed method approach, utilising measurement of cognition, questionnaires, physiological measurements and semi-structured interviews. DISCUSSION: The results of this feasibility trial will inform the design of a future adequately powered substantive trial investigating the effect of dialysate cooling on prevention and/or slowing in cognitive decline in patients undergoing haemodialysis using a computerised battery of neuro-cognitive tests. The main hypothesis that would be tested in this future trial is that patients treated with regular conventional haemodialysis will have a lesser decline in cognitive function and a better quality of life over 1 year by using cooler dialysis fluid at 35 °C, versus a standard dialysis fluid temperature of 36.5 °C. This also should reflect in improvements in their abilities for activities of daily living and therefore reduce carers' burden. If successful, the treatment could be universally applied at no extra cost. TRIAL REGISTRATION: ClinicalTrials.gov NCT03645733 . Registered retrospectively on 24 August 2018.


Subject(s)
Kidney Failure, Chronic , Quality of Life , Activities of Daily Living , Cognition , Feasibility Studies , Humans , Kidney Failure, Chronic/diagnosis , Kidney Failure, Chronic/therapy , Prospective Studies , Randomized Controlled Trials as Topic , Renal Dialysis/adverse effects , Retrospective Studies
8.
MAGMA ; 33(1): 131-140, 2020 Feb.
Article in English | MEDLINE | ID: mdl-31628564

ABSTRACT

PURPOSE: The potential of renal MRI biomarkers has been increasingly recognised, but clinical translation requires more standardisation. The PARENCHIMA consensus project aims to develop and apply a process for generating technical recommendations on renal MRI. METHODS: A task force was formed in July 2018 focused on five methods. A draft process for attaining consensus was distributed publicly for consultation and finalised at an open meeting (Prague, October 2018). Four expert panels completed surveys between October 2018 and March 2019, discussed results and refined the surveys at a face-to-face meeting (Aarhus, March 2019) and completed a second round (May 2019). RESULTS: A seven-stage process was defined: (1) formation of expert panels; (2) definition of the context of use; (3) literature review; (4) collection and comparison of MRI protocols; (5) consensus generation by an approximate Delphi method; (6) reporting of results in vendor-neutral and vendor-specific terms; (7) ongoing review and updating. Application of the process resulted in 166 consensus statements. CONCLUSION: The process generated meaningful technical recommendations across very different MRI methods, while allowing for improvement and refinement as open issues are resolved. The results are likely to be widely supported by the renal MRI community and thereby promote more harmonisation.


Subject(s)
Kidney/diagnostic imaging , Magnetic Resonance Imaging/standards , Nephrology/standards , Translational Research, Biomedical/standards , Biomarkers/metabolism , Consensus , Delphi Technique , Europe , Expert Testimony , Humans , Image Processing, Computer-Assisted , Magnetic Resonance Imaging/instrumentation , Magnetic Resonance Imaging/trends , Nephrology/trends , Reference Standards , Surveys and Questionnaires , Translational Research, Biomedical/trends , United States
9.
MAGMA ; 33(1): 141-161, 2020 Feb.
Article in English | MEDLINE | ID: mdl-31833014

ABSTRACT

OBJECTIVES: This study aimed at developing technical recommendations for the acquisition, processing and analysis of renal ASL data in the human kidney at 1.5 T and 3 T field strengths that can promote standardization of renal perfusion measurements and facilitate the comparability of results across scanners and in multi-centre clinical studies. METHODS: An international panel of 23 renal ASL experts followed a modified Delphi process, including on-line surveys and two in-person meetings, to formulate a series of consensus statements regarding patient preparation, hardware, acquisition protocol, analysis steps and data reporting. RESULTS: Fifty-nine statements achieved consensus, while agreement could not be reached on two statements related to patient preparation. As a default protocol, the panel recommends pseudo-continuous (PCASL) or flow-sensitive alternating inversion recovery (FAIR) labelling with a single-slice spin-echo EPI readout with background suppression and a simple but robust quantification model. DISCUSSION: This approach is considered robust and reproducible and can provide renal perfusion images of adequate quality and SNR for most applications. If extended kidney coverage is desirable, a 2D multislice readout is recommended. These recommendations are based on current available evidence and expert opinion. Nonetheless they are expected to be updated as more data become available, since the renal ASL literature is rapidly expanding.


Subject(s)
Cerebrovascular Circulation , Kidney/diagnostic imaging , Magnetic Resonance Imaging/trends , Spin Labels , Translational Research, Biomedical/trends , Algorithms , Consensus , Delphi Technique , Echo-Planar Imaging , Humans , Image Processing, Computer-Assisted/methods , Kidney/blood supply , Kidney Transplantation , Magnetic Resonance Angiography , Multicenter Studies as Topic , Perfusion , Renal Artery/diagnostic imaging , Reproducibility of Results , Signal-To-Noise Ratio
10.
BMC Nephrol ; 20(1): 432, 2019 11 27.
Article in English | MEDLINE | ID: mdl-31771527

ABSTRACT

BACKGROUND: Chronic kidney disease (CKD) is an independent risk factor for stroke in the general population. The impact of prior stroke on major clinical outcomes in CKD populations is poorly characterised. METHODS: The Salford Kidney Study is a UK prospective cohort of more than 3000 patients recruited since 2002 and followed until March 2018. Multivariable Cox regression examined associations of stroke at two time points; cohort inception, and at dialysis initiation, with risks of death, non-fatal cardiovascular events (NFCVE) and end stage renal disease (ESRD). RESULTS: 277 (9.1%) of 3060 patients suffered a prior stroke and this was associated with mortality, ESRD and future NFCVE after cardiovascular risk factor adjustments. Median survival for prior stroke patients was 40 months vs 77 months in patients without a stroke. Prior stroke was independently associated with mortality (HR 1.20 95%CI 1.0-1.43, p = 0.05). Of 579 patients who reached ESRD and commenced dialysis, a prior stroke (N = 48) was independently associated with mortality. Median survival for the prior stroke group was 29 months compared with 50 months for the non-stroke group. Only 70 and 75% of patients who had suffered an ischaemic stroke were prescribed antiplatelets or statins respectively. CONCLUSIONS: A diagnosis of stroke is strongly and independently associated with several adverse clinical outcomes for patients with CKD. Prior stroke profoundly alters cardiovascular risk in CKD patients. Greater attention to primary and secondary preventive strategies is warranted which may improve these outcomes.


Subject(s)
Renal Dialysis/statistics & numerical data , Renal Insufficiency, Chronic , Stroke , Aged , Cardiovascular Diseases/epidemiology , Cohort Studies , Disease Progression , Female , Glomerular Filtration Rate , Humans , Kidney Failure, Chronic/epidemiology , Male , Mortality , Prospective Studies , Renal Insufficiency, Chronic/diagnosis , Renal Insufficiency, Chronic/mortality , Renal Insufficiency, Chronic/therapy , Risk Assessment , Stroke/diagnosis , Stroke/epidemiology , United Kingdom/epidemiology
11.
Perit Dial Int ; 39(5): 486-489, 2019.
Article in English | MEDLINE | ID: mdl-31501293

ABSTRACT

Peritoneal ultrafiltration (PuF) has been employed for severe heart failure (HF), but evidence for its benefit is lacking. The Peritoneal Dialysis for Heart Failure (PDHF) study was a multicenter prospective randomized controlled trial which aimed to investigate this issue. The trial stopped early due to inadequate recruitment. We describe methods, trial activity, and lessons learned.The trial aimed to recruit 130 participants with severe diuretic-resistant HF (New York Heart Association [NYHA] 3/4) and chronic kidney disease (CKD) stage 3/4 on optimal medical treatment for ≥ 4 weeks from 6 UK centers. Participants were randomized to either continuation of conventional HF treatment or to additionally receiving PuF (1 overnight exchange using Icodextrin dialysate). Primary outcome was change in 6-minute walk test (6MWT) between baseline and 28 weeks (end of trial). Secondary outcomes were changes in patient reported quality of life as assessed by the Kansas City Cardiomyopathy Questionnaire, short form 36 (SF 36) health survey results, hospitalization, and mortality.Over a 2-year period, 290 patients were screened from which only 20 met inclusion criteria and 10 were recruited. Reasons for ineligibility were fluctuating estimated glomerular filtration rate (eGFR), suboptimal HF treatment, frailty, and patients being too unwell for randomization. Barriers to recruitment included patient frailty, with some participants considered only when they were at end of life, unwillingness to engage in an invasive therapy, and suboptimal coordination between cardiology and renal services. This is a challenging patient group in which to perform research, and lessons learned from the peritoneal dialysis (PD)-HF trial will be helpful in the planning of future studies in this area.


Subject(s)
Heart Failure/therapy , Hemodiafiltration , Peritoneal Dialysis/methods , Randomized Controlled Trials as Topic , Aged , Heart Failure/complications , Humans , Middle Aged , Prospective Studies , Renal Insufficiency, Chronic/complications , Renal Insufficiency, Chronic/therapy
12.
Am J Nephrol ; 50(2): 152-159, 2019.
Article in English | MEDLINE | ID: mdl-31269482

ABSTRACT

BACKGROUND: If loss of functioning nephrons predisposes to glomerular barotrauma (a "remnant nephron" effect), then glomerular permeability should increase as glomerular filtration rate (GFR) falls, as is observed in animal models of nephron loss. METHODS: Changes in net renal protein permeability, defined as proteinuria or albuminuria per mL/min of GFR, were measured in the setting of nephron loss due to kidney donation (Assessing Long Term Outcomes in Living Kidney Donors cohort) or progressive chronic kidney disease (CKD; Modification of Diet in Renal Disease [MDRD], African American Study of Kidney Disease [AASK], and Chronic Renal insufficiency Cohort [CRIC] studies). RESULTS: Following kidney donation, renal albumin permeability increased by 31% from predonation levels (p < 0.001). With progression of CKD, a 50% loss of residual GFR was accompanied by increases in proteinuria per mL/min GFR of 1.8-, 2.1-, and 1.6-fold in the MDRD, AASK, and CRIC cohorts, respectively (p < 0.001 for all), independent of changes in systolic blood pressure and ACEi/ARB use. A 70% reduction in GFR was associated with permeability increases of 3.1-, 4.4-, and 2.6-fold in the same cohorts. Among MDRD participants with progression of nonglomerular primary disease, the 75th percentile of final permeability was 141 mg/24 h proteinuria per mL/min GFR. This degree of permeability would have resulted in nephrotic range proteinuria had it been present at the baseline mean GFR of 40 mL/min, implying the development of de novo glomerular pathology as GFR fell. Increasing permeability also accompanied CKD progression in participants with nephrotic syndrome at baseline. Consequently, these participants had little improvement in 24 h proteinuria or serum albumin, despite substantial loss of functioning nephron mass across which the protein leak occurred. In the absence of a fall in GFR, there was no increase in permeability in any cohort. CONCLUSION: Nephron loss is accompanied by an increase in renal protein permeability, even in the absence of a primary glomerular disease. This is consistent with a remnant nephron effect in human CKD.


Subject(s)
Glomerular Filtration Rate/physiology , Nephrectomy/adverse effects , Nephrons/metabolism , Proteinuria/physiopathology , Renal Insufficiency, Chronic/physiopathology , Adult , Aged , Animals , Disease Progression , Female , Humans , Living Donors , Male , Middle Aged , Nephrons/physiopathology , Permeability , Prospective Studies , Proteinuria/etiology , Renal Insufficiency, Chronic/complications , Risk Factors , Serum Albumin, Human/metabolism , Tissue and Organ Procurement
14.
Hemodial Int ; 23(3): 356-365, 2019 07.
Article in English | MEDLINE | ID: mdl-30920718

ABSTRACT

INTRODUCTION: Structural and functional brain white matter abnormalities are poorly characterized in patients with end-stage kidney disease. METHODS: We examined the prevalence of the brain white matter microstructure disruption using diffusion tensor magnetic resonance imaging and its association with hemodynamic performance and cognitive defects in 49 incident hemodialysis (HD) patients and compared these to 25 age-matched normal controls. We analyzed fractional anisotropy (FA) and mean diffusivity (MD) maps of the images, a voxelwise statistical analysis was done using tract-based spatial statistics. Hemodynamic assessment was done using extrema points analysis model of continuous blood pressure monitoring. FINDINGS: We found significant white matter damage in HD patients compared with normal controls (peak FA 0.471 ± 0.031 vs 0.486 ± 0.022 P = 0.023, peak MD 0.00194 ± 0.000363 10-3 mm2 .s-1 vs 0.00167 ± 0.0003 10-3 mm2 .s-1 P = 0.002). There was diffuse pattern of white matter damage in HD patients, which was independent of age, gender, and the presence of ischaemic heart disease and diabetes with significantly lower FA values in HD patients than normal controls (0.467 ± 0.037 vs 0.507 ± 0.026, P < 0.05 corrected for family wise error. HD patients had worse cognitive scores that correlated with white matter damage (for peak FA, Montreal cognitive assessment r = 0.478 P = 0.001, Trail A r = -0.486 P = 0.001, Trail B r = -0.464 P = 0.001; for peak MD, Montreal cognitive assessment r = -0.533 P < 0.001, Trail A r = 0.641 P < 0.001, Trail B r = 0.514 P < 0.001). In a multivariable linear regression analysis that included age, smoking, the presence of ischaemic heart disease, and diabetes mellitus, higher frequency of mean arterial blood pressure extrema points during HD was independently associated with white matter damage (ß = -0.296, P = 0.036, Adjusted R2 for the whole model = 0.400). DISCUSSION: End-stage kidney disease patients on HD have more brain white matter damage and cognitive impairment than age-matched controls that are linked to hemodynamic functional measures.


Subject(s)
Brain/pathology , Cognitive Dysfunction/etiology , Kidney Failure, Chronic/complications , White Matter/pathology , Adolescent , Adult , Aged , Aged, 80 and over , Cognitive Dysfunction/pathology , Diffusion Tensor Imaging , Female , Humans , Kidney Failure, Chronic/pathology , Longitudinal Studies , Male , Middle Aged , Renal Dialysis , Young Adult
15.
Front Physiol ; 9: 1106, 2018.
Article in English | MEDLINE | ID: mdl-30174610

ABSTRACT

Background: Measuring the extent to which renal artery stenosis (RAS) alters renal haemodynamics may permit precision medicine by physiologically guided revascularization. This currently requires invasive intra-arterial pressure measurement with associated risks and is rarely performed. The present proof-of-concept study investigates an in silico approach that uses computational fluid dynamic (CFD) modeling to non-invasively estimate renal artery haemodynamics from routine anatomical computed tomography (CT) imaging of RAS. Methods: We evaluated 10 patients with RAS by CT angiography. Intra-arterial renal haemodynamics were invasively measured by a transducing catheter under resting and hyperaemic conditions, calculating the translesional ratio of distal to proximal pressure (Pd/Pa). The diagnostic and quantitative accuracy of the CFD-derived virtual Pd/Pa ratio (vPd/Pa) was evaluated against the invasively measured Pd/Pa ratio (mPd/Pa). Results: Hyperaemic haemodynamics was infeasible and CT angiography in 4 patients had insufficient image resolution. Resting flow data is thus reported for 7 stenosed arteries from 6 patients (one patient had bilateral RAS). The comparison showed a mean difference of 0.015 (95% confidence intervals of ± 0.08), mean absolute error of 0.064, and a Pearson correlation coefficient of 0.6, with diagnostic accuracy for a physiologically significant Pd/Pa of ≤ 0.9 at 86%. Conclusion: We describe the first in silico estimation of renal artery haemodynamics from CT angiography in patients with RAS, showing it is feasible and diagnostically accurate. This provides a methodological framework for larger prospective studies to ultimately develop non-invasive precision medicine approaches for studies and interventions of RAS and resistant hypertension.

16.
Nephrol Dial Transplant ; 33(suppl_2): ii15-ii21, 2018 09 01.
Article in English | MEDLINE | ID: mdl-30137581

ABSTRACT

Renal perfusion provides the driving pressure for glomerular filtration and delivers the oxygen and nutrients to fuel solute reabsorption. Renal ischaemia is a major mechanism in acute kidney injury and may promote the progression of chronic kidney disease. Thus, quantifying renal tissue perfusion is critically important for both clinicians and physiologists. Current reference techniques for assessing renal tissue perfusion have significant limitations. Arterial spin labelling (ASL) is a magnetic resonance imaging (MRI) technique that uses magnetic labelling of water in arterial blood as an endogenous tracer to generate maps of absolute regional perfusion without requiring exogenous contrast. The technique holds enormous potential for clinical use but remains restricted to research settings. This statement paper from the PARENCHIMA network briefly outlines the ASL technique and reviews renal perfusion data in 53 studies published in English through January 2018. Renal perfusion by ASL has been validated against reference methods and has good reproducibility. Renal perfusion by ASL reduces with age and excretory function. Technical advancements mean that a renal ASL study can acquire a whole kidney perfusion measurement in less than 5-10 min. The short acquisition time permits combination with other MRI techniques that might inform drug mechanisms and renal physiology. The flexibility of renal ASL has yielded several variants of the technique, but there are limited data comparing these approaches. We make recommendations for acquiring and reporting renal ASL data and outline the knowledge gaps that future research should address.


Subject(s)
Acute Kidney Injury/physiopathology , Kidney/physiology , Practice Guidelines as Topic/standards , Renal Artery/physiology , Renal Circulation/physiology , Spin Labels , Humans , Kidney/blood supply , Magnetic Resonance Imaging/methods
17.
Nephrol Dial Transplant ; 33(suppl_2): ii4-ii14, 2018 09 01.
Article in English | MEDLINE | ID: mdl-30137584

ABSTRACT

Functional renal magnetic resonance imaging (MRI) has seen a number of recent advances, and techniques are now available that can generate quantitative imaging biomarkers with the potential to improve the management of kidney disease. Such biomarkers are sensitive to changes in renal blood flow, tissue perfusion, oxygenation and microstructure (including inflammation and fibrosis), processes that are important in a range of renal diseases including chronic kidney disease. However, several challenges remain to move these techniques towards clinical adoption, from technical validation through biological and clinical validation, to demonstration of cost-effectiveness and regulatory qualification. To address these challenges, the European Cooperation in Science and Technology Action PARENCHIMA was initiated in early 2017. PARENCHIMA is a multidisciplinary pan-European network with an overarching aim of eliminating the main barriers to the broader evaluation, commercial exploitation and clinical use of renal MRI biomarkers. This position paper lays out PARENCHIMA's vision on key clinical questions that MRI must address to become more widely used in patients with kidney disease, first within research settings and ultimately in clinical practice. We then present a series of practical recommendations to accelerate the study and translation of these techniques.


Subject(s)
Biomarkers/analysis , Magnetic Resonance Imaging/methods , Renal Insufficiency, Chronic/classification , Renal Insufficiency, Chronic/pathology , Disease Progression , Humans , Renal Insufficiency, Chronic/therapy
19.
Nephrology (Carlton) ; 22(11): 864-871, 2017 Nov.
Article in English | MEDLINE | ID: mdl-27470704

ABSTRACT

BACKGROUND: It is unknown whether patients recruited to renal cardiac imaging studies are fully representative of the investigated population and whether there are differences in characteristics and survival between participants and non-participants (excluded or declined consent). Subjects and Methods Four hundred thirty-five maintenance haemodialysis patients were screened in an observational, prospective study. Baseline demographics, laboratory results, social deprivation scores and survival data were collected from patient records. All patients were followed-up until death, renal transplantation or 16 November 2015. RESULTS: Forty-four patients were excluded (16 language barrier, 10 mental incapacity, 9 severe co-morbid illness and 9 because of immobility), 172 patients declined consent (84% due to reluctance to attend for an extra visit) and 219 patients were recruited. Excluded patients had a lower mean haemoglobin (10.2 g/dL vs 10.7 g/dL), phosphate (4.15 mg/dL vs 4.74 mg/dL), albumin (3.6 g/dL vs 3.8 g/dL) and higher C-reactive protein (3.2 mg/dL vs 1.6 mg/dL) compared with recruited patients. No difference was identified between groups for Charleston comorbidity index (P = 0.115) or social deprivation scores. After a median follow-up of 29.7 (25th-75th percentile, 21.1-34.3) months, there were 141 deaths. In a multivariable Cox regression model adjusting for BMI, age, Charleston comorbidity index, haemoglobin, albumin, smoking status and diabetes mellitus, patients who declined consent had an adjusted HR of 1.70, 95% CI 1.10-2.52, and excluded patients had an adjusted HR of 1.30, 95% CI 0.75-2.25, for all-cause mortality compared with recruited patients. CONCLUSIONS: Patients recruited to the study had longer survival compared with non-participants. Research studies should document phenotypes of non-participants to aid interpretation and generalizability of results.


Subject(s)
Echocardiography , Patient Selection , Renal Dialysis , Selection Bias , Aged , Aged, 80 and over , Female , Follow-Up Studies , Humans , Male , Middle Aged , Proportional Hazards Models , Prospective Studies
20.
Semin Dial ; 29(6): 435-441, 2016 11.
Article in English | MEDLINE | ID: mdl-27556272

ABSTRACT

Cardiac dysfunction is a key factor in the high morbidity and mortality rates seen in hemodialysis (HD) patients. Much of the dysfunction is manifest as adverse changes in cardiac and vascular structure prior to commencing dialysis. This adverse vascular remodeling arises as a dysregulation between pro- and antiproliferative signaling pathways in response to hemodynamic and nonhemodynamic factors. The HD procedure itself further promotes cardiomyopathy by inducing hypotension and episodic regional cardiac ischemia that precedes global dysfunction, fibrosis, worsening symptoms, and increased mortality. Drug-based therapies have been largely ineffective in reversing HD-associated cardiomyopathy, in part due to targeting single pathways of low yield. Few studies have sought to establish natural history and there is no framework of priorities for future clinical trials. Targeting intradialytic cardiac dysfunction by altering dialysate temperature, composition, or ultrafiltration rate might prevent the development of global cardiomyopathy, heart failure, and mortality through multiple pathways. Novel imaging techniques show promise in characterizing the physiological response to HD that is a unique model of repetitive ischemia-reperfusion injury. Reducing HD-associated cardiomyopathy may need a paradigm shift from empirical delivery of solute clearance to a personalized therapy balancing solute and fluid removal with microvascular protection. This review describes the evidence for intradialytic cardiac dysfunction outlining cardioprotective strategies that extend to multiple organs with potential impacts on exercise tolerance, sleep, cognitive function, and quality of life.


Subject(s)
Cardiomyopathies/etiology , Heart/physiopathology , Kidney Failure, Chronic/complications , Renal Dialysis/adverse effects , Cardiomyopathies/prevention & control , Dialysis Solutions , Humans , Hypotension/etiology , Ischemia/complications , Quality of Life , Vascular Remodeling
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