"Black"-Appearing Peritoneal Effluent

When encountering unusually appearing dialysate effluent from a patient doing peri- toneal dialysis, it is important to review the patient's recent exposures. In the case of "black"-appearing dialysate effluent, consideration needs to be given to the possibility of someone having undergone a colonoscopy and having tattooing with India ink. Nephrology nurses are frequently the first to be notified when there has been a change in the character of a patient's peritoneal dialysis dialysate effluent. This article describes a case of "black"-appearing dialysate and includes some of the potential differentials that were considered in the evaluation process. Even though "black"-appearing dialysate is a rare occurrence, nephrology nurses need to be aware of some of the potential etiologies, including exposure to India ink.

Urinary CYP eicosanoid excretion correlates with glomerular filtration in African-Americans with chronic kidney disease

Previous studies have indicated that cytochrome P450 (CYP) metabolites of arachidonic acid (AA), i.e., 20-hydroxyeicosatetraenoic acid (20-HETE) and epoxyeicosatrienoic acids (EETs), play an important role in the regulation of renal tubular and vascular function. The present study for the first time profiled HETEs and epoxygenase derived dihydroxyeicosatetraenoic acid diHETEs levels in spot urines and plasma in 262 African American patients from the University of Mississippi Chronic Kidney Disease Clinic and 31 African American controls. Significant correlations in eGFR and urinary 20-HETE/creatinine and 19-HETE/creatinine levels were observed. The eGFR increased by 17.47 [p=0.001] and 60.68 [(p=0.005]ml/min/for each ng/mg increase in 20-HETE and 19-HETE levels, respectively. Similar significant positive associations were found between the other urinary eicosanoids and eGFR and also with 19-HETE/urine creatinine concentration and proteinuria. We found that approximately 80% of plasma HETEs and 30% diHETEs were glucuronidated and the fractional excretion of 20-HETE was less than 1%. These results suggest that there is a significant hepatic source of urinary 20-HETE glucuronide and EETs with extensive renal biotransformation to metabolites which may play a role in the pathogenesis of CKD.

Abstract 348: Urinary CYP Eicosanoid Excretion Correlates with Glomerular Filtration in African-Americans with Chronic Kidney Disease

Previous studies have indicated that cytochrome P450 (CYP) metabolites of arachidonic acid, ie, 20-hydroxyeicosatetraenoic acid (20-HETE) and epoxyeicosatrienoic acids (EETs) play an important role in the regulation of renal tubular function and vascular tone. More recent studies suggest that variants in the CYP4A11 and CYP4F2 genes are linked to the development of hypertension in a variety of human population studies. However, little is known about the role of 20-HETE or EETs in the pathogenesis of hypertension or diabetic induced renal disease because CYP eicosanoids have not been measured in patients with CKD. The present study profiled HETEs and the dihydroxy metabolites of EETs (DHETs) levels, from spot urines at the time of their clinic visit using LC/MS/MS in 106 African-American patients from the University of Mississippi (UMC) Chronic Kidney Disease (CKD) Clinic with various etiologies of renal disease. Informed consent was obtained for this UMMC IRB approved protocol. Significant positive correlations were found between urinary 5,6- DHETE, 8,9-DHETE, 11,12-DIHETE, 14,15-DHETE, 20-HETE and 19-, 15- and 8-HETE levels and estimated GFR (eGFR) as derived from the MDRD. The magnitude of the influence of urinary eicosanoid levels on eGFR was relatively profound since the slopes of these relationships indicated that there is a 5-10% decrement eGFR associated with each ng/ml fall in urinary eicosanoid levels. These results suggest that a decline in the renal formation of 20-HETE and/or EETs may contribute to the pathogenesis of CKD. At very least, urinary CYP eicosanoids may serve as a useful biomarker for progressive disease.

Human and murine kidneys show gender- and species-specific gene expression differences in response to injury

The incidence of End Stage Renal Disease (ESRD) is approximately 50% higher in men than women. In order to understand the molecular basis of this gender disparity, we examined sex specific gene expression patterns in control and diseased, human and murine kidney samples. Using the Affymetrix platform we performed comprehensive gene expression analysis on 42 microdissected human kidney samples (glomeruli and tubules). We identified 67 genes with gender biased expression in healthy human kidneys and 24 transcripts in diseased male and female human kidneys. Similar analysis performed in mice using male and female control and doxorubicin induced nephrotic syndrome kidneys identified significantly larger number of differentially expressed transcripts. The majority of genes showing gender biased expression either in diseased human and murine kidneys were different from those differentially expressed in healthy kidneys. Only 9 sexually dimorphic transcripts were common to healthy human and murine kidneys and five showed differential regulation in both human and murine diseased kidneys. In humans, sex biased genes showed statistical enrichment only to sex chromosomes while in mice they were enriched to sex chromosomes and various autosomes. Thus we present a comprehensive analysis of gender biased genes in the kidney. We show that sexually dimorphic genes in the kidney show species specific regulation. Our results also indicate that male and female kidneys respond differently to injury. These studies could provide the basis for the development of new treatment strategies for men and women with kidney disease.