Risk and Timing of Major Bleeding Complications Requiring Intervention of the Percutaneous Kidney Biopsy With a Short Observation Protocol: A Retrospective Chart Review.

Background: We previously published a retrospective study of kidney biopsies performed in a tertiary care hospital in London, Ontario from 2012 to 2017. This study resulted in a change of practice in our institution to shorter postbiopsy monitoring for outpatients as well as the development of a risk calculator to predict serious bleeding complications. Objective: The primary objective of this study was to determine whether this shorter monitoring time is adequate in the outpatient setting. A secondary objective was to validate the bleeding risk calculator in both inpatients and outpatients. Design: This was a retrospective chart review. Setting: This study was performed at a tertiary academic hospital in London, Ontario, Canada. Participants: This was a retrospective study of 400 adult patients who underwent kidney biopsy between April 30, 2018 and February 25, 2022 at a tertiary academic hospital in London, Canada. Methods: We retrospectively assessed frequency and timing of major bleeding complications in patients who underwent kidney biopsy. In secondary analyses, we examined the prediction performance of the risk calculator in discrimination and calibration. Results: Major bleeding occurred in 7 patients (1.8%). Five of these patients required blood transfusions (1.3%) and 2 required embolization (0.5%). In the outpatient setting, any major bleeding events were identified immediately (1 patient) or on the routine 2-hour ultrasounds (1 patient). The risk calculator showed good discrimination (C-statistic, 0.91, 95% confidence interval [CI] = [0.84 to 0.95]) and calibration (slope, 1.10, 95% CI = [0.47 to 1.74]; intercept, 95% CI = -0.02 [-0.79 to 0.75]), but with much uncertainty in the estimates. Limitations: The occurrence of only a few major bleeding events limits the reliability of our assessment of our risk calculator. Conclusions: There appears to be little yield in extending observation beyond 2 hours after an outpatient kidney biopsy with the use of immediate and 2-hour postbiopsy ultrasounds. The bleeding risk calculator (http://perioperativerisk.com/kbrc) warrants further validation.

Contexte: Nous avons publié précédemment une étude rétrospective des biopsies rénales effectuées entre 2012 et 2017 dans un hôpital de soins tertiaires de London, en Ontario. Les résultats de cette précédente étude ont entraîné un changement de pratique dans notre établissement, soit une réduction de la durée de la surveillance post-biopsie pour les patients ambulatoires, et la mise au point d'un calculateur de risque permettant de prédire les complications hémorragiques graves. Objectifs: L'objectif principal de l'étude en cours était de vérifier si ce temps de surveillance plus court est adéquat pour les patients ambulatoires. Un deuxième objectif était de valider le calculateur de risque d'hémorragie chez les patients hospitalisés et les patients ambulatoires. Conception: Étude rétrospective des dossiers médicaux. Cadre: Étude réalisée dans un hôpital de soins tertiaires de London, en Ontario (Canada). Sujets: Cette étude rétrospective portait sur 400 patients adultes ayant subi une biopsie rénale entre le 30 avril 2018 et le 25 février 2022 dans un centre hospitalier universitaire de soins tertiaires de London, au Canada. Méthodes: Nous avons procédé à un examen rétrospectif de la fréquence des complications hémorragiques graves, et du moment où celles-ci surviennent, chez les patients ayant subi une biopsie rénale. Dans les analyses secondaires, nous avons examiné la puissance prédictive du calculateur de risque en matière de discrimination et d'étalonnage. Résultats: Sept patients (1,75 %) ont subi une hémorragie majeure; de ces patients, cinq ont eu besoin de transfusions sanguines (1,3 %) et deux, d'une embolisation (0,5 %). En contexte ambulatoire, tous les événements hémorragiques graves ont été détectés immédiatement (un patient) ou lors de l'échographie de routine à deux heures (un patient). Le calculateur de risque a montré une bonne discrimination (statistique C : 0,91 [IC 95 % : 0,84 à 0,95]) et un bon étalonnage (pente : 1,10 [0,47 à 1,74]; point d'intersection : -0,02 [-0,79 à 0,75]), mais une grande incertitude dans les estimations. Limitations: La fiabilité de l'évaluation de notre calculateur de risque est limitée par le très faible échantillon d'événements hémorragiques graves étant survenus. Conclusion: Il semble y avoir peu d'intérêt à prolonger la surveillance au-delà de deux heures après une biopsie rénale chez les patients ambulatoires lorsqu'une échographie est pratiquée immédiatement après la procédure et deux heures plus tard. Le calculateur de risque d'hémorragie (http://perioperativerisk.com/kbrc) nécessite une validation plus approfondie.

Microscopic Kidney Disease in Tuberous Sclerosis Complex and Treatment With mTOR Inhibition.

Declining kidney function in tuberous sclerosis complex (TSC) is often attributed to large lesions, including angiomyolipomas (AMLs) and cysts, that encroach on the normal parenchyma or that require intervention and loss of parenchyma from surgical debulking or embolization. Consequently, research on inhibitors of the mammalian target of rapamycin (mTOR), a protein complex implicated in TSC pathophysiology for its role in promoting cell growth and proliferation, has largely focused on their ability to reduce AML size. Clinical guidelines distilled from this research limit mTOR inhibition as a first-line treatment to patients with large AMLs. However, chronic kidney disease (CKD) occurs in patients without large AMLs or a history of renal intervention. Alternate mechanisms postulated for CKD in TSC may suggest a role for mTOR inhibition in this population. In this report, we present 2 cases of a microscopic variant of TSC kidney disease causing declining kidney function, as well as anecdotal evidence for the use of mTOR inhibition to improve kidney function in the absence of large AMLs. We highlight the importance of annual kidney function assessment in patients with TSC and suggest a low threshold for kidney biopsy in patients with declining glomerular filtration rate without a clear etiology clinically or radiographically.

Investigation of N,N,N-Trimethyl-L-alanyl-L-proline Betaine (TMAP) as a Biomarker of Kidney Function.

Glomerular filtration rate (GFR) is the most widely used tool for the measurement of kidney function, but endogenous biomarkers such as cystatin C and creatinine have limitations. A previous metabolomic study revealed N,N,N-trimethyl-L-alanyl-L-proline betaine (TMAP) to be reflective of kidney function. In this study, we developed a quantitative LCMS assay for the measurement of TMAP and evaluated TMAP as a biomarker of GFR. An assay to measure TMAP was developed using liquid chromatography-mass spectrometry. After validation of the method, we applied it to plasma samples from three distinct kidney disease patient cohorts: nondialysis chronic kidney disease (CKD) patients, patients receiving peritoneal and hemodialysis, and living kidney donors. We investigated whether TMAP was conserved in other mammalian and nonmammalian species, by analyzing plasma samples from Wistar rats with diet-induced CKD and searching for putative matches to the m/z for TMAP and its known fragments in the raw sample data repository "Metabolomics Workbench". The assay can measure plasma TMAP at a lower limit of quantitation (100 ng/mL) with an interday precision and accuracy of 12.8 and 12.1%, respectively. In all three patient cohorts, TMAP concentrations are significantly higher in patients with CKD than in controls with a normal GFR. Further, TMAP concentrations are also elevated in rats with CKD and TMAP is present in the sap produced from Acer saccharum trees. TMAP concentration is inversely related to GFR suggesting that it is a marker of kidney function. TMAP is present in nonmammalian species suggesting that it is part of a biologically conserved process.

Adults with tuberous sclerosis complex: A distinct patient population.

OBJECTIVES: There are few data on adults living with tuberous sclerosis complex (TSC), with most studies focusing on pediatric populations. The objective of our study was to examine a large national cohort of adults with TSC, and to describe the clinical characteristics of these adults and the nature of the multidisciplinary care that they receive. METHODS: Six Canadian medical centers collaborated in this study. Data were collected using a standardized form, and descriptive statistics were used for the analyses. RESULTS: Our study included 181 adults with definite TSC (mean age = 33.6 years [SD = 13.7]). More than 40% (n = 75) had family members affected by TSC. Forty-six percent (n = 83) of individuals had intellectual disability. Nearly 30% (n = 52) of individuals reported living alone or with a partner/spouse. Seventy-six percent (n = 138) of people had epilepsy, 43% (n = 59) of whom had drug-resistant epilepsy, and 21% (n = 29) had undergone epilepsy surgery. Neuropsychiatric disease (n = 128) and renal angiomyolipomas (n = 130) were both present in approximately 70% of people. Renal imaging was performed in 75.7% (n = 137) of participants within the past 3 years. Renal and pulmonary function tests, as well as electrocardiograms, were recently performed in a minority of individuals. SIGNIFICANCE: Our cohort of adults with TSC showed that an important proportion have a milder phenotype, and are more frequently familial, as compared to children with TSC (and differing from prior reports in adult cohorts). Drug-resistant epilepsy, neuropsychiatric comorbidities, and renal angiomyolipoma are challenging factors in adults with TSC. Our participating medical centers generally followed recommended screening strategies, but there remain important gaps in care. Multidisciplinary and structured TSC care centers offering service to adults may help to improve the health of this important patient population.

Potential Pitfalls in Pre-implantation Genetic Diagnosis in a Patient with Tuberous Sclerosis and Isolated Mosaicism for a TSC2 Variant in Renal Tissue.

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder that displays a wide spectrum of clinical manifestations, often affecting multiple organs including the kidneys, brain, lungs, and skin. A pathogenic mutation in either the TSC1 or TSC2 gene can be detected in almost 85% of the cases, with mosaicism accounting for about half of the remaining cases. We report a case of TSC diagnosed clinically, requesting genetic counselling regarding reproductive risks. No mutation was identified on initial testing of peripheral blood; however, mosaicism for a likely pathogenic frameshift variant in TSC2 was detected at a level of 15% in renal angiomyolipoma tissue. Despite widespread clinical manifestations of TCS, this variant was not detected in skin fibroblasts or saliva, raising the possibility this is an isolated somatic mutation in renal tissue with the underlying germline mutation not yet identified. This case highlights the difficulties when counselling patients with mosaicism regarding their reproductive risks and prenatal diagnostic options.

Autoantibodies to LG3 are associated with poor long-term survival after liver retransplantation.

Autoantibodies are detrimental to the survival of organ transplantation. We demonstrated that Angiotensin II Type I Receptor agonistic autoantibodies (AT1R-AA) were associated with poor outcomes after liver retransplantation. To examine the effect of other autoantibodies, we studied a retrospective cohort of 93 patients who received a second liver transplant. Pre-retransplant sera were tested with Luminex-based solid-phase assays. Among 33 tested autoantibodies, 15 were significantly higher in 48 patients who lost their regrafts than 45 patients whose regrafts were still functioning. Specifically, patients with autoantibodies to the C-terminal laminin-like globular domain of Perlecan (LG3) experienced significantly worse regraft survival (p = .002) than those with negative LG3 autoantibodies (LG3-A). In multivariate analysis, LG3-A (HR = 2.35 [1.11-4.98], p = .027) and AT1R-AA (HR = 2.09 [1.07-4.10], p = .032) remained significant predictors of regraft loss after adjusting for recipient age and sex. There were synergistic deleterious effects on regraft survival in patients who were double-positive for LG3-A and donor-specific antibody (DSA) (HR = 5.26 [2.15-12.88], p = .001), or LG3-A and AT1R-AA (HR = 3.23 [1.37-7.66], p = .008). All six double-positive patients lost their liver regrafts. In conclusion, LG3-A is associated with inferior long-term outcomes of a second liver transplant. Screening anti-HLA antibodies and autoantibodies such as LG3-A/AT1R-AA identifies patients with a higher risk for liver transplantation.

Long-lasting cluster of nosocomial pneumonia with a single Pneumocystis jirovecii genotype involving different organ allograft recipients.

Pneumocystis pneumonia (PCP) outbreaks may occur in solid organ transplant (SOT) patients. Transmissibility of Pneumocystis jirovecii among SOT and non-SOT patients has not been investigated. Ten SOT (ie, 4 heart, 4 kidney, 2 liver allograft recipients) and 11 non-SOT (ie, 7 HIV-infected, 3 hematologic malignancies, and 1 stem cell transplant) patients with PCP were admitted to London Health Sciences Center (LHSC) from October 2014 to August 2016. We investigated the course of illness and outcome of PCP in SOT and non-SOT patients. Post-transplant PCP was frequently an acute-onset disease (90% vs. 18.2%, p = .01) requiring ICU admission (70% vs. 20%, p = .03) and hemodialysis (60% vs. 0, p = .003). Mortality was more frequent in SOT patients (40% vs. 18.1%, p = .36). Multilocus sequence typing (MLST) demonstrated circulation of a single genotype of P. jirovecii among SOT patients. However, 8 different genotypes were detected from non-SOT patients. Reinstitution of prophylaxis successfully controlled post-transplant cluster until end of observation period in October 2019. No transmission was detected from non-SOT patients to SOT recipients. Detection of a single P. jirovecii genotype from all SOT recipients highlights the likelihood of nosocomial transmission. No source control method is recommended by current guidelines. Improvement of preventive strategies is required.

The effect of human leukocyte antigen A1 and B35-Cw4 on sustained BK polyomavirus DNAemia after renal transplantation.

Human leukocyte antigen (HLA) class I presentation pathway plays a central role in natural killer (NK) cell and cytotoxic T-cell activities against BK polyomavirus (BKPyV) DNAemia. We determined the risk of sustained BKPyV DNAemia in 175 consecutive renal transplant recipients considering the simultaneous effect of donor/recipient HLA class I antigens and pre- or post-transplant variables. Median (IQR) age was 53 (44-64) years, and 37% of patients were female. 40 patients (22.9%) developed sustained BKPyV DNAemia [median (IQR) viral load: 9740 (4350-17 125) copies/ml]. In the Cox proportional hazard analysis, HLA-A1 (HR: 3.06, 95% CI: 1.51-6.17) and HLA-B35-Cw4 (HR: 4.63, 95% CI: 2.12-10.14) significantly increased the risk of sustained BKPyV DNAemia, while 2 HLA-C mismatches provided a marginally protective effect (HR: 0.32, 95% CI: 0.10-0.98). HLA-Cw4 is a ligand for NK cell inhibitory receptor, and HLA-B35 is in strong linkage disequilibrium with the HLA-Cw4 allele. The association between HLA-B35-Cw4 expression and sustained BKPyV DNAemia supports the important role of cytotoxic T cells and NK cells that would normally control BKPyV activation through engagement with immunoglobulin-like killer receptors (KIRs). Further studies are required to investigate the effect of HLA-C alleles along with NK cell activity against BKPyV DNAemia.

Starch or Saline After Cardiac Surgery: A Double-Blinded Randomized Controlled Trial.

BACKGROUND: Despite decades of investigation, the balance of clinical risks and benefits of fluid supplementation with starch remain unresolved. Patient-centered outcomes have not been well explored in a "real-world" trial in cardiac surgery. OBJECTIVE: We sought to compare a starch-based fluid strategy with a saline-based fluid strategy in the cardiac surgery patient. DESIGN: A pragmatic blinded randomized controlled trial comparing starch-based with saline-based fluid strategy. SETTING: A large tertiary academic center in London Ontario between September 2009 and February 2011. PARTICIPANTS: Patients undergoing planned, isolated coronary revascularization. MEASUREMENTS: Serum creatinine and patient weight were measured daily postoperatively. METHODS: Patients were randomized to receive 6% hydroxyethyl starch (Voluven) or saline for perioperative fluid requirements. Fluid administration was not protocolized. Co-primary outcomes were incidence of acute kidney injury (AKI) and maximum postoperative weight gain. Secondary outcomes included bleeding, transfusion, inotropic and ventilator support, and fluid utilization. RESULTS: The study was prematurely terminated due to resource limitations. A total of 69 patients (19% female, mean age = 65) were randomized. Using RIFLE criteria for AKI, "risk" occurred in 12 patients in each group (risk ratio [RR] = 1.0; 95% confidence interval [CI] = 0.5-1.9; P = 1.00), whereas "injury" occurred in 7 of 35 (20%) and 3 of 34 (9%) of patients in the starch and saline groups, respectively (RR = 2.3; 95% CI = 0.6-8.1; P = .31). Maximum weight gain, bleeding and blood product usage, and overall fluid requirement were similar between groups. LIMITATIONS: The study had to be prematurely terminated due to resource limitations which led to a small sample size which was not sufficiently powered to detect a difference in the primary outcomes. CONCLUSIONS: This pragmatic double-blinded randomized controlled trial revealed a number of interesting hypothesis-generating trends and confirmed the feasibility of undertaking a logistically complex trial in a pragmatic fashion.

CONTEXTE: L'équilibre entre les avantages et les risques cliniques d'une supplémentation en fluides à base d'amidon n'est toujours pas établi malgré des décennies d'études. Les résultats des patients subissant une chirurgie cardiaque n'ont pas été explorés suffisamment dans le cadre d'un essai concret. OBJECTIF: Comparer deux stratégies de supplémentation liquidienne, une solution à base d'amidon et une solution saline, chez des patients subissant une chirurgie cardiaque. TYPE D'ÉTUDE: Un essai pragmatique, contrôlé, à répartition aléatoire et mené en double insu comparant deux stratégies de supplémentation liquidienne une solution à base d'amidon et une solution saline. CADRE: Un grand centre universitaire de soins tertiaires de London (Ontario) entre septembre 2009 et février 2011. SUJETS: Des patients subissant une revascularisation coronarienne planifiée et isolée. MESURES: La créatinine sérique et le poids du patient ont été mesurés quotidiennement à la suite de l'intervention. MÉTHODOLOGIE: Les patients ont été répartis aléatoirement pour recevoir du Voluven (solution d'amidon hydroxyéthylé à 6 %) ou une solution saline pour les fluidiques périopératoires. L'administration ne s'est pas faite selon un protocole établi. L'incidence d'insuffisance rénale aiguë (IRA) et un gain pondéral maximal après l'intervention constituaient les deux principaux résultats mesurés. Les résultats secondaires incluaient une hémorragie, l'utilisation de transfusion sanguine, d'inotrope, d'assistance respiratoire et l'administration de fluides. RÉSULTATS: L'étude a été interrompue prématurément par manque de ressources. Les 69 patients (19 % de femmes) répartis aléatoirement avaient en moyenne 65 ans. La classification RIFLE avait permis de détecter un « risque ¼ d'IRA chez 12 patients dans chacun des groupes (RC: 1,0; IC 95 %: 0,5-1,9; p=1,00) et une « insuffisance ¼ chez 7 patients sur 35 (20 %) du groupe « amidon ¼ et 3 patients sur 34 (9 %) du groupe « saline ¼ (RC: 2,3; IC 95 %: 0,6-8,1; p=0,31). Le gain pondéral maximal, le nombre d'hémorragies, l'utilisation de produits sanguins et les besoins liquidiens étaient similaires dans les deux groupes. LIMITES: L'étude a été interrompue prématurément en raison d'un manque de ressources. Par conséquent, le faible échantillon de patients s'avère insuffisamment puissant pour détecter des différences significatives entre les deux groupes. CONCLUSIONS: Cette étude a mis en lumière quelques tendances permettant d'émettre des hypothèses intéressantes. L'étude a également confirmé la possibilité d'entreprendre un essai logistique complexe de manière pragmatique.

Frequency, Timing, and Prediction of Major Bleeding Complications From Percutaneous Renal Biopsy.

BACKGROUND AND OBJECTIVES: The risk and timing of bleeding events following ultrasound-guided percutaneous renal biopsy are not clearly defined. DESIGN SETTING PARTICIPANTS AND MEASUREMENTS: We performed a retrospective study of 617 consecutive adult patients who underwent kidney biopsy between 2012 and 2017 at a tertiary academic hospital in London, Canada. We assessed frequency and timing of minor (not requiring intervention) and major (requiring blood transfusion, surgery, or embolization) bleeds and developed a personalized risk calculator for these. RESULTS: Bleeding occurred in 79 patients (12.8%; 95% confidence interval [CI]: 10.4%-15.7%). Minor bleeding occurred in 67 patients (10.9%; 95% CI: 8.6%-13.6%). Major bleeding occurred in 12 patients (1.9%; 95% CI: 1.1%-3.4%); 2 required embolization or surgery (0.3%; 95% CI: 0.09%-1.2%) and 10 required blood transfusion (1.6%; 95% CI: 0.9%-3.0%). Seventy-three of 79 events were identified immediately on post-procedure ultrasound (92.4% of cases; 95% CI: 84.4%-96.5%). Four of 617 patients experienced a minor event not detected immediately (0.6%; 95% CI: 0.3%-1.7%). Two patients (0.3%; 95% CI: 0.09%-1.2%) suffered a major complication that was not recognized immediately; both required blood transfusions only. There were no deaths or nephrectomies. A risk calculator using age, body mass index, platelet count, hemoglobin concentration, size of the target kidney, and whether the kidney is native, or an allograft predicted minor (C-statistic, 0.70) and major bleeding (C-statistic, 0.83). CONCLUSIONS: This retrospective study of 617 patients who had percutaneous ultrasound-guided renal biopsies supports the safety of short post-biopsy monitoring for most patients. A risk calculator can further personalize estimates of complication risk (http://perioperativerisk.com/kbrc).

CONTEXTE: Les risques d'hémorragie et le moment où surviennent ces événements après une biopsie rénale percutanée échoguidée ne sont pas clairement définis. MÉTHODOLOGIE: Nous avons procédé à une étude rétrospective sur 617 patients adultes consécutifs ayant subi une biopsie rénale entre 2012 et 2017 dans un center hospitalier universitaire de soins tertiaires de London, au Canada. Nous avons analysé la fréquence des saignements et le moment où est survenue une hémorragie mineure (ne nécessitant aucune intervention) ou majeure (nécessitant une transfusion sanguine, une chirurgie ou une embolisation). Un calculateur de risque a ultérieurement été développé pour chacun. RÉSULTATS: Des 617 patients étudiés, 79 (12,8 %; IC 95 % : 10,4 %-15,7 %) ont vécu un événement hémorragique mineur (n=67 [10,9 %]; IC 95 % : 8,6 %-13,6 %) ou majeur (n=12 [1,9 %]; IC 95 % : 1,1 %-3,4 %). Deux hémorragies majeures ont nécessité une embolisation ou une chirurgie (0,3 %; IC 95 % : 0,09 %-1,2 %), les dix autres ayant été traitées par transfusion sanguine (1,6 %; IC 95 % : 0,9 %-3,0 %). Des 79 événements rapportés, 73 ont été détectés à l'échographie immédiatement après l'intervention (92,4 % des cas; IC 95 % : 84,4 %-96,5 %). Quatre patients (0,6 %; IC 95 % : 0,3 %-1,7 %) ont subi une complication mineure n'ayant pas été détectée immédiatement après la biopsie. Deux patients (0,3 %; IC 95 % : 0,09 %-1,2 %) ont souffert d'une complication majeure n'ayant pas été reconnue immédiatement, mais qui n'a nécessité que des transfusions sanguines. Aucun décès ou néphrectomie n'a été rapporté. Un calculateur du risque d'hémorragie utilisant l'âge, l'indice de masse corporelle, la numération plaquettaire, le taux d'hémoglobine, la taille du rein biopsié, et tenant compte du fait que le rein est natif ou une allogreffe, a pu prédire un événement mineur (statistique C = 0,70) ou majeur (statistique C = 0,83). CONCLUSION: Cette étude rétrospective sur 617 patients confirme qu'il serait prudent d'assurer une surveillance de courte durée pour la plupart des patients qui subissent une biopsie percutanée échoguidée. L'emploi d'un calculateur du risque d'hémorragie précise davantage le risque de complications estimé (http://perioperativerisk.com/kbrc).

Angiotensin II type I receptor agonistic autoantibodies are associated with poor allograft survival in liver retransplantation.

Angiotensin II type I receptor (AT1R) agonistic autoantibodies (AT1R-AA) are detrimental to kidney transplantation. Early studies suggested a similar negative effect in primary liver transplantation. Here, we studied AT1R-AA in a retrospective cohort of 94 patients who received a second liver transplant to determine their prevalence and effects. The concentrations of preformed AT1R-AA before transplantation were higher (P = .019) in the 48 patients who lost their liver grafts than in the 46 patients whose grafts survived. About half (48/94, 51.1%) of the patients were positive for AT1R-AA >17 U/mL before the second liver transplantation. In 22 (23.4%) patients, strong positive AT1R-AA (defined as >40 U/mL) were detected, of whom 16 (72.7%) patients lost their grafts. Based on Kaplan-Meier analysis, patients with strong positive AT1R-AA had significantly worse graft survival than those with AT1R-AA <40 U/mL (P = .035). In multivariate Cox models that included confounders such as sex and age, either AT1R-AA >40 U/mL (HR = 1.999 [1.085-3.682], P = .026) or increased concentrations of AT1R-AA (HR = 1.003 [1.001-1.006] per incremental U/mL, P = .019) were significantly associated with elevated risk for graft loss. In conclusion, our data indicate that there is a high prevalence of AT1R-AA in candidates for second liver transplantation and that their presence is associated with inferior long-term outcomes of the second graft.

Untargeted metabolomics reveals N, N, N-trimethyl-L-alanyl-L-proline betaine (TMAP) as a novel biomarker of kidney function.

The diagnosis and prognosis of chronic kidney disease (CKD) currently relies on very few circulating small molecules, which can vary by factors unrelated to kidney function. In end-stage renal disease (ESRD), these same small molecules are used to determine dialysis dose and dialytic clearance. Therefore, we aimed to identify novel plasma biomarkers to estimate kidney function in CKD and dialytic clearance in ESRD. Untargeted metabolomics was performed on plasma samples from patients with a single kidney, non-dialysis CKD, ESRD and healthy controls. For ESRD patients, pre- and post-dialysis plasma samples were obtained from several dialysis modalities. Metabolomics analysis revealed over 400 significantly different features in non-dialysis CKD and ESRD plasma compared to controls while less than 35 features were significantly altered in patients with a single kidney. N,N,N-trimethyl-L-alanyl-L-proline betaine (TMAP, AUROC = 0.815) and pyrocatechol sulfate (AUROC = 0.888) outperformed creatinine (AUROC = 0.745) in accurately identifying patients with a single kidney. Several metabolites accurately predicted ESRD; however, when comparing pre-and post-hemodialysis, TMAP was the most robust biomarker of dialytic clearance for all modalities (AUROC = 0.993). This study describes TMAP as a novel potential biomarker of kidney function and dialytic clearance across several hemodialysis modalities.

Albuminuria and Allograft Failure, Cardiovascular Disease Events, and All-Cause Death in Stable Kidney Transplant Recipients: A Cohort Analysis of the FAVORIT Trial.

RATIONALE & OBJECTIVE: Cardiovascular disease (CVD) is common and overall graft survival is suboptimal among kidney transplant recipients. Although albuminuria is a known risk factor for adverse outcomes among persons with native chronic kidney disease, the relationship of albuminuria with cardiovascular and kidney outcomes in transplant recipients is uncertain. STUDY DESIGN: Post hoc longitudinal cohort analysis of the Folic Acid for Vascular Outcomes Reduction in Transplantation (FAVORIT) Trial. SETTING & PARTICIPANTS: Stable kidney transplant recipients with elevated homocysteine levels from 30 sites in the United States, Canada, and Brazil. PREDICTOR: Urine albumin-creatinine ratio (ACR) at randomization. OUTCOMES: Allograft failure, CVD, and all-cause death. ANALYTICAL APPROACH: Multivariable Cox models adjusted for age; sex; race; randomized treatment allocation; country; systolic and diastolic blood pressure; history of CVD, diabetes, and hypertension; smoking; cholesterol; body mass index; estimated glomerular filtration rate (eGFR); donor type; transplant vintage; medications; and immunosuppression. RESULTS: Among 3,511 participants with complete data, median ACR was 24 (Q1-Q3, 9-98) mg/g, mean eGFR was 49±18 (standard deviation) mL/min/1.73m2, mean age was 52±9 years, and median graft vintage was 4.1 (Q1-Q3, 1.7-7.4) years. There were 1,017 (29%) with ACR < 10mg/g, 912 (26%) with ACR of 10 to 29mg/g, 1,134 (32%) with ACR of 30 to 299mg/g, and 448 (13%) with ACR ≥ 300mg/g. During approximately 4 years, 282 allograft failure events, 497 CVD events, and 407 deaths occurred. Event rates were higher at both lower eGFRs and higher ACR. ACR of 30 to 299 and ≥300mg/g relative to ACR < 10mg/g were independently associated with graft failure (HRs of 3.40 [95% CI, 2.19-5.30] and 9.96 [95% CI, 6.35-15.62], respectively), CVD events (HRs of 1.25 [95% CI, 0.96-1.61] and 1.55 [95% CI, 1.13-2.11], respectively), and all-cause death (HRs of 1.65 [95% CI, 1.23-2.21] and 2.07 [95% CI, 1.46-2.94], respectively). LIMITATIONS: No data for rejection; single ACR assessment. CONCLUSIONS: In a large population of stable kidney transplant recipients, elevated baseline ACR is independently associated with allograft failure, CVD, and death. Future studies are needed to evaluate whether reducing albuminuria improves these outcomes.

The Risk of Acute Rejection Following Kidney Transplant by 25-Hydroxyvitamin D and 1,25-Dihydroxyvitamin D Status: A Prospective Cohort Study.

BACKGROUND: Prediction of acute kidney transplant rejection remains imperfect despite several known risk factors. There is an increasing appreciation of the potential importance of the vitamin D pathway in immunological disease and transplantation. OBJECTIVE: The purpose of this study was to determine the association of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D with acute rejection. DESIGN: This was a prospective cohort study. SETTING: Three academic adult kidney transplant programs in Ontario, Canada, were chosen. PATIENTS: All consecutive adult patients at the 3 institutions who received a solitary kidney transplant, were able to provide written informed consent, and planned to be followed at the same center post-operatively were included. MEASUREMENTS: Serum concentration of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D were measured at baseline, 3, and 6 months post-transplantation. Acute rejection was classified using Banff criteria. METHODS: The co-primary outcome was the association between 25-hydroxyvitamin D or 1,25-dihydroxyvitamin D and time to first occurrence of biopsy-proven acute rejection (BPAR) within the first year after kidney transplantation. Cox proportional hazards models were fitted taking into account the time-varying nature of serum concentrations of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D. RESULTS: From 556 screened patients, data on 327 kidney transplant recipients are included. First BPAR occurred in 54 (16.5%) patients. In adjusted Cox proportional hazards models, the serum concentration of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D was not associated with acute renal transplant rejection (hazard ratio 1.00; 95% [confidence interval] CI, 0.87-1.14, per 10 nmol/L increase, and hazard ratio 0.97; 95% CI, 0.84-1.12, per 10 pmol/L increase, respectively). LIMITATIONS: Given the observational design, we cannot rule out the possibility of residual confounding that limited our ability to detect a clinically significant effect of vitamin D metabolites on acute rejection. CONCLUSIONS: A low serum concentration of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D is not associated with an increased risk of acute kidney transplant rejection following kidney transplantation.

CONTEXTE: La prévision du rejet aigu d'une greffe de rein demeure imparfaite en dépit des connaissances au sujet de plusieurs facteurs de risque. On remarque cependant un intérêt croissant en regard de l'importance potentielle que pourrait jouer la voie métabolique de la vitamine D dans la maladie immunologique et la transplantation. OBJECTIF: Le but de cette étude était d'établir si les concentrations sériques de 25-dihydroxyvitamine D et de 1,25-hydroxyvitamine D sont associées au phénomène de rejet aigu du greffon. MODÈLE D'ÉTUDE: Il s'agit d'une étude de cohorte prospective. CADRE DE L'ÉTUDE: L'étude s'est tenue au sein de trois programmes universitaires de greffe de rein chez des adultes en Ontario, au Canada. PATIENTS: L'étude a inclus tous les patients adultes ayant reçu une greffe solitaire de rein dans les trois établissements concernés, qui pouvaient fournir un consentement écrit et qui avaient prévu être suivis au même centre à la suite de l'intervention. MESURES: Les concentrations sériques de 25-hydroxyvitamine D et de 1,25-dihydroxyvitamine D ont été mesurées tout juste après l'intervention et à nouveau après 3 mois et 6 mois. Le rejet aigu a été déterminé en utilisant la classification de Banff. MÉTHODOLOGIE: Le principal critère attendu était une corrélation entre un faible taux de 25-hydroxyvitamine D et de 1, 25-dihydroxyvitamine D et le moment où survient le premier cas avéré par biopsie d'un rejet aigu au cours de l'année suivant la transplantation. Pour l'analyse, des modèles de risques proportionnels de Cox ont été adaptés en tenant compte du fait que les concentrations sériques de 25-dihydroxyvitamine D et de 1,25-hydroxyvitamine D varient au fil du temps. RÉSULTATS: Parmi les 556 patients sélectionnés, on a retenu les données de 327 receveurs d'une transplantation rénale. Les cas avérés par biopsie d'un premier rejet aigu sont survenus chez 54 de ces patients (16,5 %). Dans les modèles de risques proportionnels de Cox adaptés, les concentrations sériques de 25-hydroxyvitamine D et de 1, 25-dihydroxyvitamine D n'ont pas été associées à un rejet aigu de greffe rénale (risque relatif à 1,00 [IC à 95 %: 0,87, 1,14] par augmentation de 10 nmol/L et à 0,97 [IC95: 0,84, 1,12] par augmentation de 10 pmol/L, respectivement). LIMITES DE L'ÉTUDE: Compte tenu du modèle observationnel de l'étude, nous ne pouvons exclure la possibilité que des variables résiduelles confondantes aient limité notre capacité à détecter un effet clinique significatif des métabolites de la vitamine D sur le rejet aigu. CONCLUSIONS: Une faible concentration sérique de 25-hydroxyvitamine D et 1, 25-dihydroxyvitamine D n'est pas associée à un risque accru de rejet aigu du greffon consécutif à une transplantation rénale.

Enzymatic and non-enzymatic mechanisms of dimesna metabolism.

The chemical reduction of the disulfide homodimer dimesna to its constituent mesna moieties is essential for its mitigation of nephrotoxicity associated with cisplatin and ifosfamide anticancer therapies and enhancement of dialytic clearance of the cardiovascular risk factor homocysteine. The objective of this study was to investigate potential enzymatic and non-enzymatic mechanisms of intracellular dimesna reduction. Similar to endogenous intracellular disulfides, dimesna undergoes thiol-disulfide exchange with thiolate anion-forming sulfhydryl groups via the two-step SN2 reaction. Determination of equilibrium constants of dimesna reduction when mixed with cysteine or glutathione provided a mechanistic explanation for dramatic cysteine and homocysteine depletion, but sparing of the endogenous antioxidant glutathione, previously observed during mesna therapy. Dimesna was reduced by recombinant enzymes of the thioredoxin system; however, oxidation of NADPH by the glutaredoxin system was only observed in the presence of combined dimesna and reduced glutathione, suggesting formation of oxidized glutathione following an initial non-enzymatic reduction of dimesna. Production of mesna by enzymatic and non-enzymatic mechanisms in HeLa cell lysate following dimesna incubation was demonstrated by a loss in mesna production following protein denaturation and prediction of residual non-enzymatic mesna production by mathematical modeling of thiol-disulfide exchange reactions. Reaction modeling also revealed that mixed disulfides make up a significant proportion of intracellular thiols, supporting their role in providing additional nephroprotection, independent of direct platinum conjugation.

Levofloxacin for BK virus prophylaxis following kidney transplantation: a randomized clinical trial.

IMPORTANCE: BK virus infection is a significant complication of modern immunosuppression used in kidney transplantation. Viral reactivation occurs first in the urine (BK viruria) and is associated with a high risk of transplant failure. There are currently no therapies to prevent or treat BK virus infection. Quinolone antibiotics have antiviral properties against BK virus but efficacy at preventing this infection has not been shown in prospective controlled studies. OBJECTIVE: To determine if levofloxacin can prevent BK viruria in kidney transplant recipients. DESIGN, SETTING, AND PARTICIPANTS: Double-blind, placebo-controlled randomized trial involving 154 patients who received a living or deceased donor kidney-only transplant in 7 Canadian transplant centers between December 2011 and June 2013. INTERVENTIONS: Participants were randomly assigned to receive a 3-month course of levofloxacin (500 mg/d; n = 76) or placebo (n = 78) starting within 5 days after transplantation. MAIN OUTCOMES AND MEASURES: The primary outcome was time to occurrence of BK viruria (detected using quantitative real-time polymerase chain reaction) within the first year after transplantation. Secondary outcomes included BK viremia, peak viral load, rejection, and patient and allograft survival. RESULTS: The mean follow-up time was 46.5 weeks in the levofloxacin group and 46.3 weeks in the placebo group (27 patients had follow-up terminated before the end of the planned follow-up period or development of viruria because the trial was stopped early owing to lack of funding). BK viruria occurred in 22 patients (29%) in the levofloxacin group and in 26 patients (33.3%) in the placebo group (hazard ratio, 0.91; 95% CI, 0.51-1.63; P = .58). There was no significant difference between the 2 groups in regard to any of the secondary end points. There was an increased risk of resistant infection among isolates usually sensitive to quinolones in the levofloxacin group vs placebo (14/24 [58.3%] vs 15/45 [33.3%], respectively; risk ratio, 1.75; 95% CI, 1.01-2.98) as well as a nonsignificant increased risk of suspected tendinitis (6/76 [7.9%] vs 1/78 [1.3%]; risk ratio, 6.16; 95% CI, 0.76-49.95). CONCLUSIONS AND RELEVANCE: Among kidney transplant recipients, a 3-month course of levofloxacin initiated early following transplantation did not prevent BK viruria. Levofloxacin was associated with an increased risk of adverse events such as bacterial resistance. These findings do not support the use of levofloxacin to prevent posttransplant BK virus infection. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT01353339.

Preoperative Cylex assay predicts rejection risk in patients with kidney transplant.

INTRODUCTION AND OBJECTIVES: The ImmuKnow assay measures cell-mediated immunity by quantifying ATP release from CD4+ T-cells in peripheral blood. Herein, we hypothesized that this assay could predict complications associated with over-/under-immunosuppression in patients with kidney transplant (KT). METHODS: Sixty-seven patients undergoing KT were recruited prospectively and had ATP levels measured preoperatively, and at specified intervals over two months. Clinicians were blinded to ATP levels. Clinical events including rejection and infection/cancer were documented with a median follow-up of 21 months. Parameters including absolute ATP levels and changes in ATP patterns (slopes, delta) were analyzed. Association between ATP parameters and clinical outcomes was compared using the likelihood-ratio test and Kaplan-Meier curves. RESULTS: Absolute ATP values postoperatively had poor predictive value with regard to rejection or infection/malignancy. As well, changes in ATP values were poorly associated with complications. Importantly, patients with pre-transplant ATP values <300 ng/mL had significantly less rejection episodes vs. those with ATP values >300 ng/mL (p < 0.0001). CONCLUSIONS: For the first time, we have evidence that a preoperative ImmuKnow level can stratify patients with KT into low/high risk groups for rejection. Future studies used to assess the utility of this assay to design individualized immunosuppressive regimens are required.

Quinolone prophylaxis for the prevention of BK virus infection in kidney transplantation: study protocol for a randomized controlled trial.

BACKGROUND: BK virus infection has emerged as a major complication in kidney transplantation leading to a significant reduction in graft survival. There are currently no proven strategies to prevent or treat BK virus infection. Quinolone antibiotics, such as levofloxacin, have demonstrated activity against BK virus. We hypothesize that administration of a quinolone antibiotic, when given early post-transplantation, will prevent the establishment of BK viral replication in the urine and thus prevent systemic BK virus infection. METHODS/DESIGN: The aim of this pilot trial is to assess the efficacy, safety and feasibility of a 3-month course of levofloxacin in the kidney transplant population. This is a multicenter, randomized, double-blind, placebo-controlled trial with two parallel arms conducted in 11 Canadian kidney transplant centers. A total of 154 patients with end-stage renal disease undergoing kidney transplantation will be randomized to receive a 3-month course of levofloxacin or placebo starting in the early post-transplant period. Levofloxacin will be administered at 500 mg po daily with dose adjustments based on kidney function. The primary outcome will be the time to occurrence of BK viruria within the first year post-transplantation. Secondary outcomes include BK viremia, measures of safety (adverse events, resistant infections,Clostridium difficile-associated diarrhea), measures of feasibility (proportion of transplanted patients recruited into the trial), proportion of patients adherent to the protocol, patient drop-out and loss to follow-up,and use of quinolone antibiotics outside of the trial protocol. DISCUSSION: Results from this pilot study will provide vital information to design and conduct a large, multicenter trial to determine if quinolone therapy decreases clinically meaningful outcomes in kidney transplantation. If levofloxacin significantly reduces BK viruria and urine viral loads in kidney transplantation, it will provide important justification to progress to the larger trial. If the full trial shows that levofloxacin significantly reduces BK infection and improves outcomes, its use in kidney transplantation will be strongly endorsed given the lack of proven therapies for this condition. TRIAL REGISTRATION: This trial was funded by the Canadian Institutes of Health Research (grant number:222493) and is registered at ClinicalTrials.gov (NCT01353339).

Pathophysiology of cardiorenal syndrome type 2 in stable chronic heart failure: workgroup statements from the eleventh consensus conference of the Acute Dialysis Quality Initiative (ADQI).

In cardiorenal syndrome (CRS) type 2, chronic heart failure (HF) results in the onset or progression of chronic kidney disease (CKD). Examples of CRS type 2 (CRS2) include progressive CKD resulting from chronic HF in congenital or acquired heart disease or from repeated bouts of acute decompensated HF. Animal data and clinical studies indicate that extended periods of chronic HF result in altered renal hemodynamics followed by progressive renal pathology. Experimental and clinical data indicate that CRS2 is characterized by mild to moderate proteinuria, a progressive decline of glomerular filtration rate, and an elevated expression of renal injury biomarkers. Important pathophysiological triggers of renal disease progression include chronic increases in renal venous pressure, maladaptive activation of the renin-angiotensin-aldosterone axis and the sympathetic nervous system, as well as a chronic inflammatory state. Intrarenal oxidative stress and proinflammatory signaling precipitate structural injury, including glomerulosclerosis and tubulointerstitial fibrosis. Yet, clinical interventional trials that directly test the impact of renin-angiotensin system antagonists and ß-blockers on the progression of CKD in CRS2 are lacking. Secondary analyses of trials designed to assess the impact of these agents on cardiovascular endpoints have failed to show a consistent benefit regarding renal functional parameters. In contrast, left ventricular assist device placement and cardiac resynchronization therapy in HF patients consistently improved renal function, suggesting a marked potential for reversibility in many cases of CRS2. Future research should be directed towards the evaluation of novel biomarkers to improve the diagnosis, severity grading as well as our understanding of the pathophysiology of CRS2. In addition, there is a need for interventional trials in HF patients to address long-term renal endpoints incorporating clinical information and measures of renal function as well as renal injury.