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Autosomal-dominant polycystic kidney disease (ADPKD) is characterized by formation of cysts from tubular epithelial cells. Previous studies indicate that secretion of prostaglandin [E.sub.2] ([PGE.sub.2]) into cyst fluid and production of cAMP underlie cyst expansion. However, the mechanism by which [PGE.sub.2] directly stimulates cAMP formation and modulates cystogenesis is still unclear, because the particular E-prostanoid (EP) receptor mediating the [PGE.sub.2] effect has not been characterized. Our goal is to define the [PGE.sub.2] receptor subtype involved in ADPKD. We used a three-dimensional cell-culture system of human epithelial cells from normal and ADPKD kidneys in primary cultures to demonstrate that [PGE.sub.2] induces cyst formation. Biochemical evidence gathered by using real-time RT-PCR mRNA analysis and immunodetection indicate the presence of [EP.sub.2] receptor in cystic epithelial cells in ADPKD kidney. Pharmacological evidence obtained by using [PGE.sub.2]-selective analogs further demonstrates that [EP.sub.2] mediates cAMP formation and cystogenesis. Functional evidence for a role of [EP.sub.2] receptor in mediating cAMP signaling was also provided by inhibiting [EP.sub.2] receptor expression with transfection of small interfering RNA in cystic epithelial cells. Our results indicate that [PGE.sub.2] produced in cyst fluid binds to adjacent [EP.sub.2] receptors located on the apical side of cysts and stimulates [EP.sub.2] receptor expression. [PGE.sub.2] binding to [EP.sub.2] receptor leads to cAMP signaling and cystogenesis by a mechanism that involves protection of cystic epithelial cells from apoptosis. The role of [EP.sub.2] receptor in mediating the [PGE.sub.2] effect on stimulating cyst formation may have direct pharmacological implications for the treatment of polycystic kidney disease. prostaglandin; E-prostanoid; butaprost; G-protein coupled receptor; polycystic kidney disease, three-dimensional cell culture system

Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common genetic disorders and carries a high health burden since it progresses to renal failure in half of the afflicted individuals by the 6th decade of life. Currently, there is no effective treatment to slow the progression of ADPKD. Rapamycin, a drug most commonly used as an immunosuppressive agent for organ transplantation, slows cystogenesis in several rodent models of polycystic kidney disease; however, its efficacy in human ADPKD is unknown. We tested the ability of rapamycin to inhibit cyst formation in an in vitro model of ADPKD using cystic epithelial cells derived from the cyst walls of kidneys from patients with ADPKD. Cystic epithelial cells were cultured in a 3-dimensional matrix of Matrigel and collagen I. In the absence of rapamycin, numerous large cystic structures formed when visualized by phase-contrast microscopy. Rapamycin decreased cyst size and cyst number in a dose-dependent manner. The concentration of rapamycin that decreased cyst number by 50% ([IC.sub.50]) was 1.4 [+ or -] 0.2 nM, a level achievable with current dosing regimens in transplantation. Staining nuclei with DAPI and then examining the gels with an inverted fluorescent microscope further visualized cell structures. This revealed that rapamycin was not toxic to cystic epithelial cells and supported the formation of branching tubule-like structures in the 3-dimensional gels. This study demonstrates that rapamycin inhibits cystogenesis by human ADPKD cystic epithelial cells. Rapamycin is a potent immunosuppressive agent, which has many potential side effects. This study provides further impetus to subject otherwise healthy individuals at the early stage of ADPKD to many years of rapamycin in a prospective clinical trial. Key words: polycystic kidney disease, rapamycin, human, 3-dimensional cultures, INTRODUCTION Autosomal dominant polycystic kidney disease (ADPKD) affects 1 in a 1,000 individuals, making it one of the most common genetic disorders [1]. ADPKD progresses to renal failure in half [...]

It has been suggested that African Americans have decreased effectiveness with immunosuppressive drugs. Data regarding the pharmacokinetics of tacrolimus in African Americans are limited. We present the case of an African American child in whom management of nephrotic syndrome caused by focal segmental glomerulosclerosis has been challenging due to unpredictable patient specific pharmacokinetic disposition of tacrolimus. Racial differences have been documented in literature to have an important impact on the pharmacokinetics and pharmacodynamics of certain drugs. As a result, African American patients may require larger doses or more frequent administration of certain medications to achieve therapeutic efficacy compared to Caucasians and other ethnic groups. Key words: African American, FK506, pharmacokinetics, tacrolimus, INTRODUCTION Focal segmental glomerulosclerosis (FSGS) is a disorder characterized by segmental glomerular scars involving some but not all glomeruli [1]. Patients will have proteinuria that is often nephrotic in presentation [...]

Background: Few studies have compared clinical outcomes and medication use between obese and nonobese children in the pediatric intensive care unit (PICU). Objectives: The primary objective was to compare clinical outcomes including mortality, PICU length of stay (LOS), and mechanical ventilation (MV) requirement between obese and nonobese children. Secondary objectives included analysis of factors associated with these outcomes and medication use between groups. Methods: This retrospective study included children 2 to 17 years old admitted to the PICU over a 1-year time frame. Patients were categorized as obese, body mass index (BMI) ≥ 95th percentile, and nonobese (BMI < 95th percentile). Three binary regression models assessed the impact of obesity on clinical outcomes. Results : There were 834 admissions, with 22.1% involving obese children. There was no difference in mortality, MV requirement, or PICU LOS between groups. There were no associations with obesity and clinical outcomes found, but an association was noted for medication classes and receipt of continuous infusions on clinical outcomes. There was no difference noted in the median number (interquartile range [IQR]) of medications between obese and nonobese children, 8 (6-13) versus 9 (6-15), P =.38, but there was a difference in patients receiving a continuous infusion between obese and nonobese children, 24.4% versus 8.8%, P <.01. The 15 most used medications in both groups included analgesics, antimicrobials, corticosteroids, bronchodilators, and gastrointestinal agents. Conclusions : One-fifth of all admissions included obese children. Obesity was not associated with mortality, PICU LOS, and MV requirement, but the number of medication classes and continuous infusions were associated with these outcomes. [ABSTRACT FROM AUTHOR]

Autosomal-dominant polycystic kidney disease (ADPKD) is characterized by formation of cysts from tubular epithelial cells. Previous studies indicate that secretion of prosta-glandin E2 (PGE2) into cyst fluid and production of cAMP underlie cyst expansion. However, the mechanism by which PGE2 directly stimulates cAMP formation and modulates cystogenesis is still unclear, because the particular E-prostanoid (EP) receptor mediating the PGE2 effect has not been characterized. Our goal is to define the PGE2 receptor subtype involved in ADPKD. We used a three-dimensional cell-culture system of human epithelial cells from normal and ADPKD kidneys in primary cultures to demonstrate that PGE2 induces cyst formation. Biochemical evidence gathered by using real-time RT-PCR mRNA analysis and immunodetection indicate the presence of EP2 receptor in cystic epithelial cells in ADPKD kidney. Pharmacological evidence obtained by using PGE2-selective analogs further demonstrates that EP2 mediates cAMP formation and cystogenesis. Functional evidence for a role of EP2 receptor in mediating cAMP signaling was also provided by inhibiting EP2 receptor expression with transfection of small interfering RNA in cystic epithelial cells. Our results indicate that PGE2 produced in cyst fluid binds to adjacent EP2 receptors located on the apical side of cysts and stimulates EP2 receptor expression. PGE2 binding to EP2 receptor leads to cAMP signaling and cystogenesis by a mechanism that involves protection of cystic epithelial cells from apoptosis. The role of EP2 receptor in mediating the PGE2 effect on stimulating cyst formation may have direct pharmacological implications for the treatment of polycystic kidney disease. [ABSTRACT FROM AUTHOR]