Levofloxacin-induced granulomatous interstitial nephritis.

The authors report the case of a 47-year-old woman in whom a systemic illness developed characterized by fever, malaise, abnormal liver function results, and acute renal failure after treatment for presumed urinary tract infection with levofloxacin. Because of suspicion of an allergic drug reaction, all medications were discontinued, but the patient remained febrile with renal failure for 18 days. Complete workup for presumed vasculitis, autoimmune illness, or infectious etiologies was negative, and the patient underwent both renal and liver biopsy. Liver biopsy results showed nonspecific changes. Renal biopsy disclosed extensive granulomatous interstitial nephritis with associated granulomatous vasculitis. The patient was begun on oral steroids with rapid defervescence of fever and progressive normalization of renal function. The authors discuss the association of granulomatous nephritis with drugs and review the known nephrotoxicity of fluoroquinolones.

Nightly intermittent peritoneal dialysis to initiate peritoneal dialysis.

Nightly intermittent peritoneal dialysis (NIPD) with no day dwell has the potential to enhance peritoneal host defenses. We evaluated outcomes in 24 patients who had been placed on NIPD at the start of peritoneal dialysis as compared with outcomes of 24 control patients on standard continuous cycling peritoneal dialysis (CCPD). As compared with patients on CCPD, patients on NIPD had a lower peritonitis rate (0.34 episodes/year vs. 0.59 episodes/year, p < 0.03) and fewer hospital admissions (1.0 admission/year vs. 1.6 admissions/year, p = 0.003). The weekly initial KtV was similar in NIPD and CCPD, but NIPD had significantly higher creatinine clearances owing to higher glomerular filtration rates (GFRs) among the patients (7.8 mL/min vs. 4.8 mL/min, p < 0.02). Technique and patient survival were similar in both groups after controlling for the difference in initial GFR. We conclude that NIPD is a good modality choice for patients starting PD with residual renal function and that it present a low peritonitis risk. As GFR declines, a last fill can be added to maintain adequate clearances.

Ontogeny of flow-stimulated potassium secretion in rabbit cortical collecting duct: functional and molecular aspects.

High urinary flow rates stimulate K secretion in the fully differentiated but not neonatal or weanling rabbit cortical collecting duct (CCD). Both small-conductance secretory K and high-conductance Ca2+/stretch-activated maxi-K channels have been identified in the apical membrane of the mature CCD by patch-clamp analysis. We reported that flow-stimulated net K secretion in the adult rabbit CCD is 1) blocked by TEA and charybdotoxin, inhibitors of intermediate- and high-conductance (maxi-K) Ca2+-activated K channels, and 2) associated with increases in net Na absorption and intracellular Ca2+ concentration ([Ca2+]i). The present study examined whether the absence of flow-stimulated K secretion early in life is due to a 1) limited flow-induced rise in net Na absorption and/or [Ca2+]i and/or 2) paucity of apical maxi-K channels. An approximately sixfold increase in tubular fluid flow rate in CCDs isolated from 4-wk-old rabbits and microperfused in vitro led to an increase in net Na absorption and [Ca2+]i, similar in magnitude to the response observed in 6-wk-old tubules, but it failed to generate an increase in net K secretion. By 5 wk of age, there was a small, but significant, flow-stimulated rise in net K secretion that increased further by 6 wk of life. Luminal perfusion with iberiotoxin blocked the flow stimulation of net K secretion in the adult CCD, confirming the identity of the maxi-K channel in this response. Maxi-K channel alpha-subunit message was consistently detected in single CCDs from animals >/=4 wk of age by RT-PCR. Indirect immunofluorescence microscopy using antibodies directed against the alpha-subunit revealed apical labeling of intercalated cells in cryosections from animals >/=5 wk of age; principal cell labeling was generally intracellular and punctate. We speculate that the postnatal appearance of flow-dependent K secretion is determined by the transcriptional/translational regulation of expression of maxi-K channels. Furthermore, our studies suggest a novel function for intercalated cells in mediating flow-stimulated K secretion.