Indra R. Gupta

Validation of child serum creatinine-based prediction equations for glomerular filtration rate

Equations for estimating glomerular filtration rate (GFR) are vital in caring for patients with renal disease and the current standard, the Schwartz formula, lacks precision. We evaluated several child serum creatinine-based GFR prediction equations. Subjects aged 2–21xa0years who underwent iothalamate GFR (IoGFR) testing between 1999 and 2004 were studied retrospectively. GFR was estimated using: (1) Schwartz formula (SchwartzGFR), using a local k value; (2) Schwartz model (SchwartzMod) using regression-derived coefficients; (3) Leger GFR (LegerGFR) using original coefficients; and (4) Leger model (LegerMod) using regression-derived coefficients. Bias, precision, and diagnostic characteristics were evaluated. There were 195 subjects [61% male; mean (SD) age 12.4 (4.5) years; mean (SD) IoGFR 78.9 (33.4) ml/min per 1.73xa0m2]. Only the LegerGFR overestimated IoGFR (5.5xa0ml/min per 1.73xa0m2). Precision for all formulae was poor (95% limits of agreement approximately −40 to 40xa0ml/min per 1.73xa0m2), but ≥72% of estimates were within 30% of IoGFR. Sensitivities for detecting IoGFRu2009<30 and 90xa0ml/min per 1.73xa0m2 were highest using the SchwartzGFR (80%) and SchwartzMod (90%), respectively. The LegerGFR was most specific. Using local coefficients, the Schwartz and Leger models were imprecise estimates of GFR, but the Schwartz model was most unbiased and sensitive. Future research should derive more precise equations for GFR in children.

Clinicopathological study of the WHO classification in childhood lupus nephritis

Over the past 10xa0years, at our center, 25 children diagnosed with systemic lupus erythematosus (SLE) have undergone an early renal biopsy; 15 underwent a second biopsy. The objective of this study was to determine whether clinical and laboratory parameters used to evaluate lupus disease activity and nephritis correlated with the WHO class on biopsy. At diagnosis, the presence of proteinuria, hematuria, a lower serum albumin, and the need for blood pressure medication were all associated with a worse class of lupus nephritis (P<0.05). On follow-up biopsy, however, none of these parameters correlated with the WHO class. Thus, it appears that while the WHO classification is useful for categorizing disease at presentation, it may be less useful for the evaluation of disease progression. Other biopsy indices need to be evaluated in serial renal biopsies to better understand the progression of lupus nephritis once treatment has been initiated.

Reversible encephalopathy associated with tacrolimus in pediatric renal transplants.

Abstractu2002Neurological complications post transplant have been described with the use of calcineurin inhibitors. Although tacrolimus may be a better immunosuppressant than cyclosporine, its neurological side effects may be worse. Two children, living-related kidney transplant recipients, were treated with antibody induction, mycophenolate mofetil, prednisone, and tacrolimus. Soon after transplant, they each developed an encephalopathy, which when visualized by magnetic resonance imaging showed that it affected both white and grey matter of the brain. Although the encephalopathy was associated with the use of tacrolimus, there was a complete neurological recovery without cessation of the drug.

High Incidence of Vesicoureteral Reflux in Mice With Fgfr2 Deletion in Kidney Mesenchyma

PURPOSEnMice with Fgfr2 conditional deletion in metanephric mesenchyma (Fgfr2(Mes-/-)) have ureteral bud induction abnormalities. We determined whether Fgfr2(Mes-/-) mutants developed abnormally positioned ureters predisposing to vesicoureteral reflux.nnnMATERIALS AND METHODSnWe measured common nephric duct length and assayed for apoptosis in embryonic day 11.5 mice. We performed 3-dimensional reconstruction of, and real-time polymerase chain reaction and whole mount in situ hybridization for Fgfr2 in urinary tracts in embryonic day 15.5 embryos. We also performed cystograms followed by 3-dimensional reconstruction in postnatal animals.nnnRESULTSnCompared with controls Fgfr2(Mes-/-) embryos had increased common nephric duct length with no difference in apoptosis, indicating cranially displaced ureteral buds. Three-dimensional reconstruction at embryonic day 15.5 showed low ureteral insertion into the bladder near the bladder neck in Fgfr2(Mes-/-) mice. Postnatal Fgfr2(Mes-/-) mutants had a high rate of vesicoureteral reflux compared with controls (47.4% vs 4.0%, p = 0.00006). In postnatal mutants with unilateral reflux the refluxing ureters inserted closer to the bladder neck than nonrefluxing ureters. External ureteral insertional angles at the outer bladder wall formed by the ureteral insertion points and the bladder neck were greater in mutant refluxing ureters than in contralateral nonrefluxing ureters or control ureters. At embryonic day 15.5 Fgfr2 was decreased in Fgfr2(Mes-/-) kidneys compared with that in controls but not statistically different in ureters or bladders.nnnCONCLUSIONSnFgfr2(Mes-/-) mice have ureteral induction abnormalities associated with abnormal ureteral insertion in the bladder and subsequent vesicoureteral reflux, consistent with the Mackie and Stephens hypothesis.

Native nephrectomy prior to pediatric kidney transplantation: biological and clinical aspects

BackgroundPre-transplant nephrectomy is performed to reduce risks to graft and recipient. The aims of this study were to evaluate (1) indications, surgical approach, and morbidity of native nephrectomy and (2) the effects of kidney removal on clinical and biological parameters.MethodsThis study was designed as a single-center retrospective cohort study in which 49 consecutive patients with uni- or bilateral native nephrectomies were identified from a total of 126 consecutive graft recipients in our pediatric kidney transplantation database between 1992 and 2011. Demographic, clinical, and laboratory details were extracted from charts and electronic records, including operation reports and pre- and post-operative clinic notes.ResultsOf the 49 nephrectomized patients, 47% had anomalies of the kidneys and urinary tract, 22% had cystinosis, 12% had focal segmental glomerulosclerosis, and 6% had congenital nephrotic syndrome. Nephrectomy decisions were based on clinical judgment, taking physiological and psychosocial aspects into consideration. Nephrectomy was performed in patients with polyuria (>2.5xa0ml/kg/h) and/or large proteinuria (>40xa0mg/m2/h), recurrent urinary tract infection or (rarely) hypertension. Urine output decreased from (median) 3.79 to 2.32xa0ml/kg/h (−34%), and proteinuria from 157 to 100xa0mg/m2/h (−40%) after unilateral nephrectomy (pu2009=u20090.005). After bilateral nephrectomy, serum albumin, protein and fibrinogen concentrations normalized in 93, 73, and 55% of nephrectomized patients, respectively. Clinically relevant procedure-related complications (peritoneal laceration, hematoma) occurred in five patients.ConclusionIn summary, we demonstrate quantitatively that native nephrectomy prior to transplantation improved serum protein levels and anticipated post-transplant fluid intake needs in select children, reducing the risk of graft hypoperfusion and its postulated consequences for graft outcome.

Claudin-7, -16, and -19 during mouse kidney development

Members of the claudin family of tight junction proteins are critical for establishing epithelial barriers and for the regulation of paracellular transport. To understand their roles during kidney development, we first performed RT-PCR analyses and determined that 23 claudin family members were expressed in embryonic day (E) 13.5 mouse kidneys. Based on their developmental expression and phenotypes in mouse models, we hypothesized that 3 claudin members could affect nephron formation during kidney development. Using whole mount in situ hybridization and immunohistochemistry, we demonstrated that Claudin-7 (Cldn7) was expressed in the nephric duct, the emerging ureteric bud, and in tubules derived from ureteric bud branching morphogenesis. In contrast, Claudin-16 (Cldn16) and Claudin-19 (Cldn19) were expressed at later stages of kidney development in immature renal tubules that become the Loop of Henle. To determine if a loss of these claudins would perturb kidney development, we examined newborn kidneys from mutant mouse models lacking Cldn7 or Cldn16. In both models, we noted no evidence for any congenital renal malformation and quantification of nephron number did not reveal a decrease in nephron number when compared to wildtype littermates. In summary, Cldn7, Cldn16, and Cldn19 are expressed in different epithelial lineages during kidney development. Mice lacking Cldn7 or Cldn16 do not have defects in de novo nephron formation, and this suggests that these claudins primarily function to regulate paracellular transport in the mature nephron.

Disorders of Kidney Formation

In this chapter, disorders of kidney formation, so-called congenital anomalies of the kidney and urinary tract (CAKUT) are defined including their epidemiology and long-term outcome. A detailed review of the molecular signaling pathways that lead to normal kidney and urinary tract formation is included with a focus on those genes and proteins that have been shown to be pertinent in animal models of CAKUT and in humans. Clinical management of unilateral renal agenesis, renal hypo/dysplasia, multicystic renal dysplasia, renal ectopia, and renal fusion anomalies is also discussed.

Cutaneous telangiectasias, sparse hair, and type I membranoproliferative glomerulonephritis

Abstractu2002We report the unusual association of normocomplementemic type I membranoproliferative glomerulonephritis in a 10-year-old girl with sparse red hair, absent eyebrows and eyelashes, cutaneous telangiectasias, and an atrial septal defect.

Electroporation of Embryonic Kidney Explants

Metanephric kidney development in the mouse begins at embryonic day (E) 10.5, when the ureteric bud (UB), an outgrowth of the epithelial nephric duct, invades the neighboring metanephric mesenchyme (MM). The ureteric bud then undergoes a series of branching events to form the collecting duct network of the adult kidney (Fig. 19.1). As each ureteric bud tip forms, the adjacent undifferentiated mesenchyme is induced to epithelialize and form a nephron, the functional unit of the adult kidney that filters waste. Rodent embryonic kidneys can be dissected and cultured as explants such that branching morphogenesis and nephrogenesis can be observed ex vivo (Rothenpieler and Dressler, 1993; Vega et al., 1996; Piscione et al., 1997; Gupta et al., 2003). The roles of signaling molecules and transcription factors during kidney development have been studied in explant cultures by introducing small interfering RNA (Davies et al., 2004), by treating with pharmaceutical agents (Tang et al., 2002), or by using viral transduction to overexpress mutant proteins (Favre et al., 2000). More recently, microinjection followed by electroporation has been used to successfully express plasmid DNA encoding proteins important for ureteric bud induction, branching morphogenesis, and nephrogenesis in the developing kidney (Gao et al., 2005; Self et al., 2006; Alie et al., 2007). This approach allows for both