Ivan Tack

GFR Estimation Using Standardized Cystatin C in Kidney Transplant Recipients

BACKGROUNDnThe utility of serum cystatin C (SCysC) as a filtration marker in kidney transplantation is uncertain. We took advantage of the recent validation of a reference calibrator for SCysC and of newly developed CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equations (2012) expressed for use with standardized SCysC level to reassess the performance of SCysC as a filtration marker in kidney transplant recipients.nnnSTUDY DESIGNnStudy of diagnostic test accuracy.nnnSETTING & PARTICIPANTSn670 kidney transplant recipients from 3 centers undergoing glomerular filtration rate (GFR) measurements from December 2006 to November 2012.nnnINDEX TESTnEstimated GFR (eGFR) using the 2012 SCysC-based and serum creatinine (SCr)/SCysC-based CKD-EPI equations (eGFR(cys) and eGFR(cr-cys), respectively) and the 2009 SCr-based CKD-EPI equation (eGFR(cr)), with SCysC and SCr measured at a single laboratory between April 2011 and June 2011.nnnREFERENCE TESTnMeasured GFR (mGFR) using urinary clearance of inulin.nnnRESULTSnBias (the difference between mGFR and eGFR) was significantly smaller for eGFR(cys) and eGFR(cr-cys) versus eGFR(cr) (-2.82 and -0.54 vs +4.4 mL/min/1.73 m(2), respectively; P < 0.001). Precision (standard deviation of the mean bias) also was better for eGFR(cys) and eGFR(cr-cys) versus eGFR(cr) (12 and 11 vs 13 mL/min/1.73 m(2) [P < 0.001 for both comparisons]). Accuracy (percentage of GFR estimates within 30% of mGFR) was greater for eGFR(cys) and eGFR(cr-cys) versus eGFR(cr) (81% and 86% vs 75%, respectively [P = 0.004 and P < 0.001]). Net reclassification index with respect to mGFR of 30 mL/min/1.73 m(2) for eGFR(cr-cys) and eGFR(cys) versus eGFR(cr) was 18.8% [95% CI, 8.6%-28.9%] and 22.5% [95% CI, 10.2%-34.9%].nnnLIMITATIONSnPatients were exclusively of European descent; association with transplant outcome was not evaluated.nnnCONCLUSIONSnOur data validate the use of both the newly developed SCysC-based and SCr/SCysC-based CKD-EPI equations (2012) in kidney transplant recipients. Both equations perform better than the SCr-based CKD-EPI equation (2009).

Renal functional decline and glomerulotubular injury are arrested but not restored by release of unilateral ureteral obstruction (UUO).

Murine unilateral ureteral obstruction (UUO), a major model of progressive kidney disease, causes loss of proximal tubular mass and formation of atubular glomeruli. Adult C57BL/6 mice underwent a sham operation or reversible UUO under anesthesia. In group 1, kidneys were harvested after 7 days. In group 2, the obstruction was released after 7 days, and a physiological study of both kidneys was performed 30 days later. Renal blood flow (RBF), glomerular filtration rate (GFR), urine protein, and albumin excretion were measured after ligation of either the left or right ureter. Glomerular volume (periodic acid-Schiff), glomerulotubular integrity and proximal tubular mass (Lotus tetragonolobus lectin), and interstitial collagen (Sirius red) were measured by histomorphometry. Obstructed kidney weight was reduced by 15% at 7 days but was not different from sham after a 30-day recovery. Glomerular volume and proximal tubular area of the obstructed kidney were reduced by 55% at 7 days, but normalized after 30 days. Interstitial collagen deposition increased 2.4-fold after 7 days of UUO and normalized after release. However, GFR and RBF were reduced by 40% and urine albumin/protein ratio was increased 2.8-fold 30 days after release of UUO. This was associated with a 50% reduction in glomerulotubular integrity despite a 30-day recovery (P < 0.05 for all data). We conclude that release of 7-day UUO can arrest progression but does not restore normal function of the postobstructed kidney. Although the remaining intact nephrons have hypertrophied, glomerular injury is revealed by albuminuria. These results suggest that glomerulotubular injury should become the primary target of slowing progressive kidney disease.

Kidney histology and function in liver transplant patients

BACKGROUNDnChronic kidney disease is a common complication after liver transplantation. However, few reports regarding kidney histology exist for this setting.nnnMETHODSnInulin clearance was measured and a kidney biopsy was performed in 99 patients at 60 ± 48 months after liver transplantation. Kidney biopsies were scored according to the Banff classification, and interstitial fibrosis was measured by a computerized quantitative method.nnnRESULTSnThere was a steep decrease in kidney function within the first 6 months following transplantation, but this lessened thereafter. At kidney biopsy, inulin clearance and estimated glomerular filtration rate (eGFR) (using the abbreviated Modification of Diet in Renal Disease equation) were highly correlated (r(2) = 0.47, P < 0.0001). A decrease in eGFR at 6 months post-transplant was the sole predictive factor for inulin clearance of < 60 mL/min/1.73 m(2) at 5 years post-transplant. Few patients had a specific pattern of kidney histopathology and all patients had complex primary lesions. Lowered eGFR at 6 months post-transplant was a predictive factor for > 50% sclerotic glomeruli on the kidney biopsy. The duration of tacrolimus therapy, as compared to cyclosporine A, was a protective factor for < 20% interstitial fibrosis on the kidney biopsy.nnnCONCLUSIONnIn the setting of liver transplantation, this is the largest kidney-histology study to confirm that histological kidney lesions are complex, multiple and interrelated. Kidney function at 6 months post-transplant can predict long-term kidney function and histology.

Beneficial effects of levobupivacaine regional anaesthesia on postoperative opioid induced hyperalgesia in diabetic mice

BackgroundDiabetic neuropathy is one of the most common complications of diabetes and causes various problems in daily life. The aim of this study was to assess the effect of regional anaesthesia on post surgery opioid induced hyperalgesia in diabetic and non-diabetic mice.MethodsDiabetic and non-diabetic mice underwent plantar surgery. Levobupivacaine and sufentanil were used before surgery, for sciatic nerve block (regional anaesthesia) and analgesia, respectively. Diabetic and non-diabetic groups were each randomly assigned to three subgroups: control, no sufentanil and no levobupivacaine; sufentanil and no levobupivacaine; sufentanil and levobupivacaine. Three tests were used to assess pain behaviour: mechanical nociception; thermal nociception and guarding behaviours using a pain scale.ResultsSufentanil, alone or in combination with levobupivacaine, produced antinociceptive effects shortly after administration. Subsequently, sufentanil induced hyperalgesia in diabetic and non-diabetic mice. Opioid-induced hyperalgesia was enhanced in diabetic mice. Levobupivacaine associated to sufentanil completely prevented hyperalgesia in both groups of mice.ConclusionThe results suggest that regional anaesthesia can decrease opioid-induced hyperalgesia in diabetic as well as in non-diabetic mice. These observations may be clinically relevant for the management of diabetic patients.

Effect of Increased Daily Water Intake in Premenopausal Women With Recurrent Urinary Tract Infections: A Randomized Clinical Trial

Importance Increased hydration is often recommended as a preventive measure for women with recurrent cystitis, but supportive data are sparse. Objective To assess the efficacy of increased daily water intake on the frequency of recurrent cystitis in premenopausal women. Design, Setting, and Participants Randomized, open-label, controlled, 12-month trial at a clinical research center (years 2013-2016). Among 163 healthy women with recurrent cystitis (≥3 episodes in past year) drinking less than 1.5 L of fluid daily assessed for eligibility, 23 were excluded and 140 assigned to water or control group. Assessments of daily fluid intake, urinary hydration, and cystitis symptoms were performed at baseline, 6- and 12-month visits, and monthly telephone calls. Interventions Participants were randomly assigned to drink, in addition to their usual fluid intake, 1.5 L of water daily (water group) or no additional fluids (control group) for 12 months. Main Outcomes and Measures Primary outcome measure was frequency of recurrent cystitis over 12 months. Secondary outcomes were number of antimicrobial regimens used, mean time interval between cystitis episodes, and 24-hour urinary hydration measurements. Results The mean (SD) age of the 140 participants was 35.7 (8.4) years, and the mean (SD) number of cystitis episodes in the previous year was 3.3 (0.6). During the 12-month study period, the mean (SD) number of cystitis episodes was 1.7 (95% CI, 1.5-1.8) in the water group compared with 3.2 (95% CI, 3.0-3.4) in the control group, with a difference in means of 1.5 (95% CI, 1.2-1.8; Pu2009<u2009.001). Overall, there were 327 cystitis episodes, 111 in the water group and 216 in the control group. The mean number of antimicrobial regimens used to treat cystitis episodes was 1.9 (95% CI, 1.7-2.2) and 3.6 (95% CI, 3.3-4.0), respectively, with a difference in means of 1.7 (95% CI, 1.3-2.1; Pu2009<u2009.001). The mean time interval between cystitis episodes was 142.8 (95% CI, 127.4-160.1) and 84.4 (95% CI, 75.4-94.5) days, respectively, with a difference in means of 58.4 (95% CI, 39.4-77.4; Pu2009<u2009.001). Between baseline and 12 months, participants in the water group, compared with those in the control group, had increased mean (SD) urine volume (1.4 [0.04] vs 0.1 [0.04] L; Pu2009<u2009.001) and voids (2.4 [0.2] vs −0.1 [0.2]; Pu2009<u2009.001) and decreased urine osmolality (−402.8 [19.6] vs −24.0 [19.5] mOsm/kg; Pu2009<u2009.001). Conclusions and Relevance Increased water intake is an effective antimicrobial-sparing strategy to prevent recurrent cystitis in premenopausal women at high risk for recurrence who drink low volumes of fluid daily. Trial Registration ClinicalTrials.gov identifier: NCT02444975

Do kidney histology lesions predict long-term kidney function after liver transplantation?

Histological renal lesions observed after liver transplantation are complex, multifactorial, and interrelated. The aims of this study were to determine whether kidney lesions observed at five yr after liver transplantation can predict long‐term kidney function. Ninety‐nine liver transplant patients receiving calcineurin inhibitor (CNI)‐based immunosuppression, who had undergone a kidney biopsy at 60 ± 48 months post‐transplant, were included in this follow‐up study. Kidney biopsies were scored according to the Banff classification. Estimated glomerular filtration rate (eGFR) was assessed at last follow‐up, that is, 109 ± 48 months after liver transplantation. eGFR decreased from 92 ± 33 mL/min at transplantation to 63 ± 19 mL/min after six months, to 57 ± 17 mL/min at the kidney biopsy, to 54 ± 24 mL/min at last follow‐up (p < 0.0001). At last follow‐up, only three patients required renal replacement therapy. After the kidney biopsy, 13 patients were converted from CNIs to mammalian target of rapamycin inhibitors, but no significant improvement in eGFR was observed after conversion. Elevated eGFR at six months post‐transplant and a lower fibrous intimal thickening score (cv) observed at five yr post‐transplant were the two independent predictive factors for eGFR ≥60 mL/min at nine yr post‐transplant. Long‐term kidney function seems to be predicted by the kidney vascular lesions.