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Reactive oxygen species (ROS) modulate sphingolipid metabolism, including enzymes that generate ceramide and sphingosine-1-phosphate (S1P), and a ROS-antioxidant rheostat determines the metabolism of ceramide-S1P. ROS induce ceramide production by activating ceramide-producing enzymes, leading to apoptosis, while they inhibit S1P production, which promotes survival by suppressing sphingosine kinases (SphKs). A ceramide-S1P rheostat regulates ROS-induced mitochondrial dysfunction, apoptotic/anti-apoptotic Bcl-2 family proteins and signaling pathways, leading to apoptosis, survival, cell proliferation, inflammation and fibrosis in the kidney. Ceramide inhibits the mitochondrial respiration chain and induces ceramide channel formation and the closure of voltage-dependent anion channels, leading to mitochondrial dysfunction, altered Bcl-2 family protein expression, ROS generation and disturbed calcium homeostasis. This activates ceramide-induced signaling pathways, leading to apoptosis. These events are mitigated by S1P/S1P receptors (S1PRs) that restore mitochondrial function and activate signaling pathways. SphK1 promotes survival and cell proliferation and inhibits inflammation, while SphK2 has the opposite effect. However, both SphK1 and SphK2 promote fibrosis. Thus, a ceramide-SphKs/S1P rheostat modulates oxidant-induced kidney injury by affecting mitochondrial function, ROS production, Bcl-2 family proteins, calcium homeostasis and their downstream signaling pathways. This review will summarize the current evidence for a role of interaction between ROS-antioxidants and ceramide-SphKs/S1P and of a ceramide-SphKs/S1P rheostat in the regulation of oxidative stress-mediated kidney diseases.

Background and Aims High-flux dialyzer membrane material has been shown to improve mortality in hemodialysis (HD) patients. However, little is known about the impact of surface area of dialyzer membrane on prognosis in HD patients. A retrospective analysis was undertaken to investigate whether the difference in high-flux dialyzer membrane area affects survival rate. Method We observed 119 patients (43 females, mean age; 68 years, and HD duration; mean 84.4 months) maintained on HD for up to 5 years and 7 months. All patients were divided into two groups according to the surface area of dialyzer membranes; S group, 39 patients treated with the dialyzer membrane area of Results The patients were treated with four types of high-flux dialyzer membranes. S group included 21 patients with cellulose triacetate (CTA), 17 patients with polysulfone (PS) and 1 patient with polymethylmethacrylate. L group included 2 patients with CTA, 71 patients with PS and 7 patients with polyethersulfone (PES). Thirty-two patients, including 12 patients in S group and 20 patients in L group, had diabetes mellitus (DM). Survival rate was compared between the two groups, patients treated with CTA, PS and PES, and those with and without DM by Kaplan-Meier method. Type of dialyzer membranes used did not affect survival rate at the final observation (65.2% in CTA, 75% in PES and 50% in PS, p=0.26). The surface area of dialyzer membrane did not have a significant impact on mortality; survival rate at 3-year for S group, 71% vs L group, 77%, at 5-year for S group, 51% vs L group, 59%, and at the final observation for S group, 48%, vs L group, 58% (p=0.352). Among 32 diabetic patients, survival rate at the final observation did not differ between the two groups (S group, 33%, vs L groups, 45%, p=0.477). Among 87 non-diabetic patients (S groups; 27 patients), survival rate did not differ between the two groups at the final observation (S group, 56%, vs L group, 63%, p=0.575). Conclusion We conclude that difference in high-flux dialyzer membrane area is unlikely to affect survival rate in HD patients.

Iron deficiency anemia (IDA) is a major problem in chronic kidney disease (CKD), causing increased mortality. Ferritin stores iron, representing iron status. Hepcidin binds to ferroportin, thereby inhibiting iron absorption/efflux. Inflammation in CKD increases ferritin and hepcidin independent of iron status, which reduce iron availability. While intravenous iron therapy (IIT) is superior to oral iron therapy (OIT) in CKD patients with inflammation, OIT is as effective as IIT in those without. Inflammation reduces predictive values of ferritin and hepcidin for iron status and responsiveness to iron therapy. Upper limit of ferritin to predict iron overload is higher in CKD patients with inflammation than in those without. However, magnetic resonance imaging studies show lower cutoff levels of serum ferritin to predict iron overload in dialysis patients with apparent inflammation than upper limit of ferritin proposed by international guidelines. Compared to CKD patients with inflammation, optimal ferritin levels for IDA are lower in those without, requiring reduced iron dose and leading to decreased mortality. The management of IDA should differ between CKD patients with and without inflammation and include minimization of inflammation. Further studies are needed to determine the impact of inflammation on ferritin, hepcidin and therapeutic strategy for IDA in CKD.

Background: We determined optimal serum ferritin for oral iron therapy (OIT) in hemodialysis (HD) patients with iron deficiency anemia (IDA)/minor inflammation, and benefit of intravenous iron therapy (IIT) for OIT-nonresponders. Methods: Inclusion criteria were IDA (Hb 3 months before the study. ΔHb ≥ 20 g/L above baseline or maintaining target Hb (tHB; 120–130 g/L) was considered responsive. Fifty-one patients received OIT (ferrous fumarate, 50 mg/day) for 3 months; this continued in OIT-responders but was switched to IIT (saccharated ferric oxide, 40 mg/week) in OIT-nonresponders for 4 months. All received continuous erythropoietin receptor activator (CERA). Hb, ferritin, hepcidin-25, and CERA dose were measured. Results: Demographics before OIT were similar between OIT-responders and OIT-nonresponders except low Hb and high triglycerides in OIT-nonresponders. Thirty-nine were OIT-responders with reduced CERA dose. Hb rose with a peak at 5 months. Ferritin and hepcidin-25 continuously increased. Hb positively correlated with ferritin in OIT-responders (r = 0.913, p = 0.03) till 5 months after OIT. The correlation equation estimated optimal ferritin of 30–40 ng/mL using tHb (120–130 g/L). Seven OIT-nonresponders were IIT-responders. Conclusions: Optimal serum ferritin for OIT is 67.4–89.9 pmol/L in HD patients with IDA/minor inflammation. IIT may be a second line of treatment for OIT-nonreponders.

Ceramide is synthesized upon stimuli, and induces apoptosis in renal tubular cells (RTCs). Sphingosine-1 phosphate (S1P) functions as a survival factor. Thus, the balance of ceramide/S1P determines ceramide-induced apoptosis. Mitochondria play a key role for ceramide-induced apoptosis by altered mitochondrial outer membrane permeability (MOMP). Ceramide enhances oligomerization of pro-apoptotic Bcl-2 family proteins, ceramide channel, and reduces anti-apoptotic Bcl-2 proteins in the MOM. This process alters MOMP, resulting in generation of reactive oxygen species (ROS), cytochrome C release into the cytosol, caspase activation, and apoptosis. Ceramide regulates apoptosis through mitogen-activated protein kinases (MAPKs)-dependent and -independent pathways. Conversely, MAPKs alter ceramide generation by regulating the enzymes involving ceramide metabolism, affecting ceramide-induced apoptosis. Crosstalk between Bcl-2 family proteins, ROS, and many signaling pathways regulates ceramide-induced apoptosis. Growth factors rescue ceramide-induced apoptosis by regulating the enzymes involving ceramide metabolism, S1P, and signaling pathways including MAPKs. This article reviews evidence supporting a role of ceramide for apoptosis and discusses a role of mitochondria, including MOMP, Bcl-2 family proteins, ROS, and signaling pathways, and crosstalk between these factors in the regulation of ceramide-induced apoptosis of RTCs. A balancing role between ceramide and S1P and the strategy for preventing ceramide-induced apoptosis by growth factors are also discussed.

Iron is an essential element for all living organisms, but produces toxic oxidants. Thus, iron homeostasis is tightly regulated in mammals. Hepcidin-25 (hepcidin) has emerged as a molecule that regulates iron metabolism. Binding of hepcidin to its receptor, ferroportin, inhibits intestinal iron absorption and iron efflux from hepatocytes and macrophages. Decreased hepcidin enhances iron absorption and efflux. Hepcidin could be predictive of iron status and the response to iron supplementation or erythropoietin-stimulating agents. Monitoring hepcidin is helpful for the management of anemia. Thus, it is urgent to obtain normal reference values in a large population of healthy subjects and to standardize various hepcidin assays, which enables to compare the data measured by different methods. Anemia is an important and common problem associated with chronic kidney disease (CKD), which is caused by erythropoietin deficiency, iron-restricted erythropoiesis, inflammation, hypoxia, vitamin D deficiency, hyperparathyroidism, and obesity. Anemia causes poor quality of life, progression of CKD, increased risk of cardiovascular events, and mortality. Besides its role in anemia, recent evidence suggests that hepcidin-25 plays a role in the pathogenesis and progression of kidney injury via modulation of iron-mediated oxidant injury. Despite accumulating experimental data, information about clinical significance of hepcidin-25 for anemia and kidney injury in CKD patients is scarce, especially in children. This review summarizes the current knowledge of the role of hepcidin-25 in the regulation of anemia and kidney injury in children and adults with CKD. Strategy for modulating hepcidin-25 to prevent anemia and kidney injury associated with CKD is also discussed.

Sphingolipids (SLs) regulate apoptosis, proliferation, and stress response. SLs, including ceramide, glycosphingolipids (glucosylceramide, lactosylceramide, and gangliosides) and sphingosine-1-phosphate (S1P), play a role in the pathogenesis and progression of genetic (lysosomal storage disease, congenital nephrotic syndrome and polycystic kidney disease) and non-genetic forms of chronic kidney diseases (CKDs). SLs metabolism defects promote complications (cardiovascular events, etc.) via oxidant stress in CKDs. A balancing role of apoptotic SLs and anti-apoptotic S1P is crucial in the regulation of glomerular injury and complications associated with CKDs. Interaction between SLs, endothelial function and reninangiotensin- aldosterone system (RAAS) plays an important role in the regulation of glomerular injury. SLs affect mitochondrial function that regulate the opening of mitochondrial permeability transition (MPT) pore, mitochondrial outer membrane permeability (MOMP), generation of reactive oxygen species (ROS), and expression of BcL-2 family proteins, which result in cytochrome c release and caspase activation, leading to apoptosis, and regulate glomerular cell proliferation or renal fibrosis. This review article summarizes the current evidence supporting a role of SLs metabolism defects in the pathogenesis and progression of glomerular injury and discusses a role of mitochondria, including MPT pore, MOMP, ROS generation, BcL-2 family proteins, interaction between SLs, endothelial function and RAAS, and SLs-induced downstream signaling events in CKDs. Crosstalk between these factors plays a role in the pathogenesis and progression of CKDs. Therapeutic strategy of targeting SLs metabolism defects for CKDs through modulation of the enzymes responsible for SLs metabolism defects is also discussed.

The benefit of oral iron therapy (OIT) and factors predictive of OIT response are not established in hemodialysis (HD) patients with iron deficiency anemia (IDA). We examined the values of hepcidin-25, mean corpuscular volume (MCV), and ferritin as predictors of OIT response. Oral ferrous fumarate (50 mg/day, 8 weeks) was given to 51 HD patients with IDA (hemoglobin (Hb) &lt, 12 g/dL, ferritin &lt, 100 ng/mL) treated with an erythropoietin activator. Sixteen patients were responders (improvement of Hb (ΔHb) ≥ 2 g/dL) and 35 were non-responders (ΔHb &lt, 2g/dL). Baseline Hb, MCV, serum hepcidin-25, ferritin, iron parameters, and C-reactive protein (CRP) before and ΔHb after OIT were compared between groups. Hepcidin-25, MCV, ferritin, and transferrin saturation were lower in the responders than in the non-responders. Hepcidin-25 positively correlated with ferritin. Hepcidin-25, MCV, and ferritin positively correlated with baseline Hb and negatively correlated with ΔHb. Despite normal CRP levels in all patients, CRP correlated positively with hepcidin-25 and ferritin. Stepwise multiple linear regression analysis and receiver operating characteristics curve analysis revealed that hepcidin-25, MCV, and ferritin could predict OIT response. We conclude that hepcidin-25, MCV, and ferritin could be useful markers of iron storage status and may help predict OIT response in HD patients.

Background/Aims: We examined whether regulation of hepcidin-25 by short- or long-acting recombinant human erythropoietin (rhEPO) is dependent on ferritin and predicts the response to rhEPO in hemodialysis (HD) patients. Methods: Two studies with rhEPO were performed in 9 HD patients with a 2-year interval. Serum hepcidin-25 was measured at 0-18 h after intravenous epoetin-β (EPO) or methoxy polyethylene glycol-epoetin-β (PEG-EPO) administration and on days 3-7 after PEG-EPO. Hemoglobin (Hb), serum ferritin, transferrin, C-reactive protein (CRP), and interleukin (IL)-6 were analyzed before hepcidin measurement and 6 months after rhEPO. Based on the serum ferritin levels before hepcidin measurement, the patients in the two studies with EPO or PEG-EPO were combined into low (11; serum ferritin of Results: The serum hepcidin-25 levels rose at 6-9 h and returned to the baseline at 18 h after EPO. They rose at 6-9 h, returned to the baseline at 18 h, and decreased on day 5-7 after PEG-EPO. Serum hepcidin-25 levels were low (Conclusion: Regulation of hepcidin-25 by rhEPO may be dependent on ferritin, affecting the response to rhEPO in HD patients.

It remains elusive whether crosstalk exists among mitochondrial Bax, caspases, and mitogen-activated protein kinases (MAPKs), and whether epidermal growth factor (EGF), which may activate MAPKs, affects ceramide-induced apoptosis through the crosstalk in renal proximal tubular cells (RPTCs). Effect of ceramide on expression of mitochondrial Bax and phosphorylated (p)-ERK, p38MAPK and JNK, that of MAPKs inhibition, and of EGF in the presence or absence of MAPKs inhibition on ceramide-induced apoptosis were examined in HK-2 cells. Apoptosis and expression of mitochondrial Bax and p-MAPKs were measured by Hoechst 33258 staining and Western blotting. C2-ceramide, but not dihydroC2-ceramide, inactive C2-ceramide, induced apoptosis at 24 h. C2-ceramide enhanced the mitochondrial Bax expression at 1 h, which was peaked at 3-6 h and decreased at 24 h, but remained increased, compared to control. An inhibitor of caspases, zVAD-fmk, ameliorated ceramide-induced apoptosis, suggesting a role of caspases for ceramide-induced apoptosis. C2-ceramide enhanced the expression of p-ERK and p-p38MAPK, but not p-JNK, at 1 h, which was increased till 24 h. An inhibitor of ERK, PD98059, or of p38MAPK, SB202190, failed to affect C2-ceramide-induced apoptosis. EGF, which enhanced the expression of p-ERK and p-p38MAPK but not p-JNK, ameliorated C2-ceramide-induced apoptosis without affecting mitochondrial Bax. Inhibition of ERK or p38MAPK failed to abolish the protective effect of EGF on C2-ceramide-induced apoptosis. Mitochondrial Bax and caspases, but not MAPKs, play a role for ceramide-induced apoptosis in RPTCs. EGF ameliorates ceramide-induced apoptosis in Bax- and MAPKs-independent pathways. The mechanism of ceramide-induced apoptosis and anti-apoptotic effect of EGF deserves further investigations.

Inactivating mutations of the V2 vasopressin receptor (V2R) cause cross-linked congenital nephrogenic diabetes insipidus (NDI), resulting in renal resistance to the antidiuretic hormone AVP. In two families showing partial NDI, characterized by an apparently normal response to diagnostic tests and an increase in the basal ADH levels suggesting AVP resistance, we have identified two V2R mutations, Ser-333del and Y128S. Both mutant V2Rs, when expressed in COS-7 cells, show partial defects in vasopressin-stimulated cAMP accumulation and intracellular localization. The inhibition of internalization does not rescue their localization. In contrast, the non-peptide V2R antagonists OPC41061 and OPC31260 partially rescue the membrane localization and basal function of these V2R mutants, whereas they inhibit the basal activity of the wild-type V2R. These results indicate that a partial loss of function of Ser-333del and Y128S mutant V2Rs results from defective membrane trafficking. These findings further indicate that V2R antagonists can act as protean agonists, serving as pharmacological chaperones for inactivating V2R mutants and also as inverse agonists of wild-type receptors. We speculate that this protean agonism could underlie the possible dual beneficial effects of the V2R antagonist: improvement of hyponatremia with heart failure or polycystic kidney disease and potential rescue of NDI.

It remains elusive what factors induce growth without growth hormone (GWGH) in children after neurosurgery of brain tumors. Growth velocity and endocrinological data were compared between the patients with and without GWGH. We experienced three patients with GWGH (median, 12 years; 2 germinoma and 1 craniopharyngioma; three females; group 1) and 11 patients without (12 years; 8 craniopharyngioma, 2 germinoma and 1 medulloblastoma; 7 males; group 2) after neurosurgery. All patients in group 2 received GH replacement therapy. Growth velocity and endocrinological data were compared. Median height velocity was normal in group 1 (5.5 cm/year), but low in group 2 (2.2 cm/year), which improved after GH replacement therapy (7.0 cm/year). Median serum insulin level was increased in group 1 (87.0 μU/ml, P < 0.05) compared with normal level in group 2 (10.0 μU/ml). Despite hyperinsulinemia, serum glucose level was normal in group 1. Three of 5 with hyperinsulinemia and 2 of 9 without were obese or overweight, but the difference was not significant. Current body mass index and serum levels of IGF-1, IGFBP-3, leptin, and prolactin were similar between groups. Serum estradiol was prepuberty level in group 1. Hyperinsulinemia may induce GWGH in children with brain tumors after neurosurgery.

Neurogenic-mediated inflammation may be associated with several inflammatory skin diseases including atopic dermatitis. However, age-dependent differences in neurogenic-mediated skin responses are not fully understood. We compared skin plasma leakage in rats aged 2 and 8 wk, which was induced by topical capsaicin, topical formalin, and intracutaneous substance P, whose effects are mediated via tachykinin NK1 receptors. Evans blue dye extravasation served as an index of the increase in skin vascular permeability. Capsaicin, formalin, and substance P caused a skin response in a dose-dependent manner in both age groups. However, the skin response was much greater in adults than in pups. In addition, the localization of sensory C-fibers and tachykinin NK1 receptors in the skin was investigated by immunofluorescent staining with antisubstance P and antitachykinin NK1 receptor antibodies, respectively. Substance P-immunoreactive nerves were detected throughout the dermis and tachykinin NK1 receptors were mainly detected in blood vessel walls in the dermis in both age groups. However, they were more sparsely distributed in pups. In conclusion, the weak neurogenic-mediated skin inflammation in pups is probably because of immature neural mechanisms associated with skin inflammation such as reduced innervation of sensory C-fibers and low expression of tachykinin NK1 receptors.

Race, young age, male gender, severe dehydration, metabolic acidosis, drowsiness/unconsciousness and shock are associated with gastroduodenal perforation/ulcer (GDPU) in childhood rotaviruses and noroviruses gastroenteritis. Awareness of the risk of GDPU prevents lethal outcome in these common infections among young children., Background. There is no literature review on gastroduodenal perforation or ulcer (GDPU) with rotavirus (RV) and norovirus (NoV) gastroenteritis. Methods. Pediatric cases of GDPU or upper gastrointestinal bleeding with RV and NoV gastroenteritis were searched from September 1974 until October 2015 using PubMed, Google for English, other-language-publications, and Ichushi (http://www.jamas.or.jp) for Japanese-language publications. All reports confirming GDPU or upper gastrointestinal bleeding with RV and NoV gastroenteritis were eligible for inclusion in the study. In addition, clinical characteristics were reviewed. Results. A boy with duodenal ulcer (DU) and NoV gastroenteritis was described. There were 32 GDPU cases (23 RVs and 9 NoVs cases), including our case; with the exception of 1 case, all were Japanese. Mean age, male/female ratio, and symptoms' duration before admission were 21.6 months, 2.2, and 4.0 days, respectively. Vomiting was the most common symptom, followed by diarrhea, lethargy, fever, abdominal distension, and convulsion. Dehydration, hematemesis, melena, drowsiness or unconsciousness, shock, metabolic acidosis, leukocytosis, anemia, positive C-reactive protein, high blood urea nitrogen, and hyponatremia commonly occurred. Helicobacter pylori was a minor cause of GDPU. Duodenal (DP) or gastric perforation (GP) developed in 14 cases (10 DP/RVs, 1 GP/RV, and 3 DP/NoVs). Duodenal ulcer or gastric ulcer (GU) developed in 18 cases (10 DU/RVs, 4 DU/NoVs, 1 GU/RV, 1 GU + DU/NoV, and 2 upper gastrointestinal bleeding/RVs). The predominant perforation or ulcer site was in the duodenum. With the exception of 2 deaths from DU, all cases recovered. Conclusions. Race, young age, male, severe dehydration, metabolic acidosis, drowsiness and unconsciousness, and shock may be potential risk factors of GDPU associated with RV and NoV gastroenteritis. Limitation of this descriptive study warrants further investigations to determine the risk factors in these infections that could be associated with GDPU.

BACKGROUND: Aplasia cutis congenita (ACC) is a condition in which localized or widespread areas of skin are absent at birth. Defective lesions show complete absence of all layers of skin, occasionally extending to skull or dura. ACC is etiologically heterogeneous; many different etiologies including teratogens have been documented. CASE: We describe the first reported case of a monozygotic twin with ACC after exposure to methimazole in utero. The female patient was born at 36 weeks gestation as the first child of monozygotic twins. The mother received methimazole between the 11th and 17th weeks of pregnancy because of transient hyperthyroidism. The second child did not have ACC. The patient had defects of the scalp, skull, and dura (7 × 5 cm) on the sagittal line of the parieto-occipital region. No other malformations were noted. The scalp defect has been treated daily with sterile physiological saline and petrolatum dressing in addition to intravenous antibiotics. Trafermin, a recombinant human fibroblast growth factor, was sprayed from day 6 to promote epithelialization of the scalp defect. On day 21, she had high fever due to infection of the defect lesion, which was controlled by povidone iodine dressing and intravenous antibiotics. The defect of the scalp was well healed after 6 weeks, but the skull defect remained unclosed. CONCLUSIONS: We describe a rare case of a monozygotic twin with ACC and skull defect after methimazole exposure in utero. The findings of our case suggest that methimazole is a potential teratogen of ACC. Birth Defects Research (Part A) 2007. © 2007 Wiley-Liss, Inc.

Key Clinical Message Norovirus (NoV) and rotavirus (RV) gastroenteritis are usually self-limiting. However, few pediatric cases of bowel perforation and no duodenal perforation with NoV gastroenteritis were reported. We describe two children with duodenal perforation due to NoV or RV gastroenteritis. Suspicion for this association enables prompt intervention, preventing lethal outcomes of these common infections.

Ischemia/reperfusion is known to result in DNA fragmentation and cell death in kidney tubular epithelium, but the endonucleases responsible for this DNA damage have not been identified. DNA substrate gel analysis of extracts from normal rat kidney cortex revealed the presence of a DNase with an apparent molecular mass of 30 to 34 kD. This enzyme is not a dimer of the previously described nuclear 15-kD endonuclease in kidney cells. Partially purified DNase exhibited characteristics similar to those of rat DNase I. The DNase was able to digest circular DNA (endonuclease), required both Ca 2+ and Mg 2+ ions, and was inhibited by Zn 2+ and by aurintricarboxylic acid; it was not inhibited by G-actin. Rat kidneys were subjected to 40 min of ischemia, followed by 0, 1, 4, 16, or 48 h of reperfusion. The activity of the DNase in cytosolic and nuclear extracts, the 200-bp ladder-generating activity, and 3′OH strand breaks in nuclear DNA were simultaneously increased after ischemia, during the first hours of reperfusion. Oxidative DNA damage, measured as 8-hydroxydeoxyguanosine content, did not coincide with endonuclease-generated DNA breaks. Oxidative DNA damage was increased during ischemia and gradually decreased during reperfusion. Phosphorothioated DNase I antisense oligodeoxynucleotide introduced into cultured NRK-52E rat kidney epithelial cells inhibited DNA fragmentation and attenuated cell death induced by hypoxia/reoxygenation in vitro . The data indicate that the DNase I-like endonuclease may contribute to DNA fragmentation in reperfused rat kidneys.

Little is known about the risk factors for long-term poor outcome in pediatric renal transplantation. Between 1973 and 2010, 111 renal transplants (92 living donations) were performed in 104 children (56 males, mean age, 12.5 yr) at the Social Insurance Chukyo Hospital, and followed-up for a mean period of 13.6 yr. The patient survival at 1, 5, 10, 15, 20 (living- and deceased-donor transplants), and 30 yr (living-donor transplants only) was 98.1%, 92.8%, 87.8%, 84.9%, 82.6%, and 79.3%. The graft survival at 1, 5, 10, 15, 20, and 30 yr was 92.0%, 77.3%, 58.4%, 50.8%, 38.5%, and 33.3%. The most common cause of graft loss was CAI, AR, death with functioning, recurrent primary disease, ATN, and malignancy. Donor gender, ATN, malignancy/cardiovascular events, and eras affected patient survival. AR and CAI were the risk factors for graft loss. The evolved immunosuppression protocols improved the outcome by reducing AR episodes and ATN but not CAI, suggesting CAI as the major risk factor for graft loss. CAI was correlated with AR episodes, CMV infection, and post-transplant hypertension. Strategies for preventing the risk factors for malignancy/cardiovascular events and CAI, including hypertension/infection, are crucial for better outcomes.

Ceramide has been implicated to play an important role in the cell signaling pathway involved in apoptosis. Most studies that have used the apoptotic model of cellular injury have suggested that enhanced ceramide generation is the result of the breakdown of sphingomyelin by sphingomyelinases. However, the role of ceramide synthase in enhanced ceramide generation in response to oxidant stress has not been previously examined in any tissue. Hydrogen peroxide (H 2 O 2 ) (1 mM) resulted in a rapid increase in ceramide generation (as measured by in vitro diacylglycerol kinase assay) in LLC-PK1 cells. The intracellular ceramide level was significantly increased at 5 min after exposure of cells to H 2 O 2 and thereafter continuously increased up to 60 min. H 2 O 2 also resulted in a rapid increase (within 5 min) in ceramide synthase activity (as measured by incorporation of [ 14 C] from the labeled palmytoyl—CoA into dihydroceramide) in microsomes. In contrast, the exposure of cells to H 2 O 2 did not result in any significant change in sphingomyelin content or acid or neutral sphingomyelinase activity. An increase in ceramide production induced by H 2 O 2 preceded any evidence of DNA damage and cell death. The specific inhibitor of ceramide synthase, fumonisin B1 (50 μM), was able to suppress H 2 O 2 -induced ceramide generation and provided a marked protection against H 2 O 2 -induced DNA strand breaks, DNA fragmentation, and cell death. Taken together, these data provide the first evidence that H 2 O 2 is a regulator of ceramide synthase rather than sphingomyelinases and that ceramide synthase—dependent ceramide generation plays a key role in DNA damage and cell death in oxidant stress to renal tubular epithelial cells.

The study of cell death has emerged as an important and exciting area of research in cell biology. Although two kinds of cell death, apoptosis and necrosis, are recognized, one of the major advances in our understanding of cell death has been the recognition that the pathways traditionally associated with apoptosis may be very critical in the form of cell injury associated with necrosis. Renal tubular epithelial cell injury from ischemia or toxins has generally been regarded as a result of a necrotic form of cell death. We briefly describe recent evidence indicating apoptotic mechanisms including endonuclease activation in renal tubular injury and some mediators (oxidants, caspases and ceramide) which regulate this process. The pathway that is followed by the cell is dependent on both the nature and severity of insults, and it is likely that the cascades that lead to the apoptotic or necrotic mode of cell death are activated almost simultaneously and may share some common pathways.

Role of enhanced ceramide generation in DNA damage and cell death in chemical hypoxic injury to LLC-PK 1 cells. Background Ceramide has been implicated to be a second messenger in the cell signaling pathway involved in cell growth, proliferation, and apoptotic cell death. However, there is little information of a role of ceramide in DNA damage and cell death in hypoxic injury known to induce necrotic cell death. Methods Ceramide generation was measured in LLC-PK 1 cells exposed to chemical hypoxia with a mitochondrial electron transport inhibitor, antimycin A and glucose deprivation. The effect of inhibition of ceramide generation on chemical hypoxia-induced DNA damage and cell death and the effect of exogenous ceramide on cellular injury were also determined. Results Chemical hypoxia resulted in a rapid increase in ceramide production prior to any evidence of DNA damage and cell death in LLC-PK 1 cells. The inhibitor of ceramide synthase, fumonisin B1, provided a marked protection against chemical hypoxia-induced DNA strand breaks, DNA fragmentation and cell death. Fumonisin B1 did not affect adenosine triphosphate (ATP) depletion induced by antimycin A, suggesting that fumonisin B1 does not alter cellular uptake of antimycin A. We confirmed the ability of ceramide synthase inhibitor, fumonisin B1, to suppress chemical hypoxia-induced ceramide generation. Exposure of LLC-PK 1 cells to synthetic ceramide, C2- and C6-ceramide, but not C2-dihydroceramide, the structural analog of C2-ceramide, resulted in DNA strand breaks, DNA fragmentation and cell death in a dose- and time-dependent manner similar to the effect of chemical hypoxia. Conclusions Our data indicate that ceramide is a key modulator for DNA damage and cell death in chemical hypoxia to renal tubular epithelial cells.

In vitro and in vivo evidence suggesting a role for iron in cisplatin-induced nephrotoxicity. Cisplatin is a widely used antineoplastic agent that has nephrotoxicity as a major side effect. The underlying mechanism of this nephrotoxicity is still not well known. Iron has been implicated to play an important role in several models of tissue injury, presumably through the generation of hydroxyl radicals via the Haber-Weiss reaction or other highly toxic free radicals. In the present study we examined the catalytic iron content and the effect of iron chelators in an in vitro model of cisplatin-induced cytotoxicity in LLC-PK1 cells (renal tubular epithelial cells) and in an in vivo model of cisplatin-induced acute renal failure in rats. Exposure of LLC-PK1 cells to cisplatin resulted in a significant increase in bleomycin-detectable iron (iron capable of catalyzing free radical reactions) released into the medium. Concurrent incubation of LLC-PK1 cells with iron chelators including deferoxamine and 1,10-phenanthroline significantly attenuated cisplatin-induced cytotoxicity as measured by lactate dehydrogenase (LDH) release. Bleomycin-detectable iron content was also markedly increased in the kidney of rats treated with cisplatin. Similarly, administration of deferoxamine in rats provided marked functional (as measured by blood urea nitrogen and creatinine) and histological protection against cisplatin-induced acute renal failure. In a separate study, we examined the role of hydroxyl radical in cisplatin-induced nephrotoxicity. Incubation of LLC-PK1 cells with cisplatin caused an increase in hydroxyl radical formation. Hydroxyl radical scavengers, dimethyl sulfoxide, mannitol and benzoic acid, significantly reduced cisplatin-induced cytotoxicity and, treatment with dimethyl sulfoxide or dimethylthiourea provided significant protection against cisplatin-induced acute renal failure. Taken together, our data strongly support a critical role for iron in mediating tissue injury via hydroxyl radical (or a similar oxidant) in this model of nephrotoxicity.

Tyrosine phosphorylation in DNA damage and cell death in hypoxic injury to LLC-PK 1 cells. Hypoxia is classically considered to result in a necrotic form of cell injury. We have recently demonstrated a role of endonuclease activation, considered a feature of apoptosis, in DNA damage and cell death in chemical hypoxic injury to renal tubular epithelial cells (LLC-PK 1 cells). Tyrosine phosphorylation has been implicated to be involved in cell signaling pathway leading to cell growth, proliferation, and apoptotic death. However, a role of tyrosine phosphorylation as a signal transduction pathway involved in DNA damage and cell death has not been previously examined in hypoxic injury in any tissue. In the present study, we have demonstrated that chemical hypoxia with a combination of antimycin A, a mitochondrial respiration inhibitor, and substrate deprivation resulted in rapid increase in protein tyrosine kinases activity and protein tyrosine phosphorylation prior to any evidence of cell death in LLC-PK 1 cells. The inhibitors of protein tyrosine kinases, genistein, lavendustin A, tyrphostin, and herbimycin A provided a marked protection against chemical hypoxia-induced DNA damage (as measured by alkaline unwinding assay) and cell death (as measured by trypan blue exclusion assay). In a separate study, we confirmed the ability of the inhibitors, lavendustin A and herbimycin A to prevent chemical hypoxia-induced increase in protein tyrosine kinases activity and protein tyrosine phosphorylation. In addition, the inhibitors used did not affect ATP depletion induced by antimycin A, suggesting that the inhibitors do not alter cellular uptake of antimycin A. Taken together, our data provide a strong evidence that tyrosine phosphorylation plays an important role in DNA damage and cell death in chemical hypoxic injury to renal tubular epithelial cells.

Hypothalamo-pituitary dysfunction is commonly seen in children with brain tumors after neurosurgery, resulting in endocrine disorders, including growth hormone deficiency (GHD). GHD causes growth failure, and thus the majority of the patients need GH replacement therapy. Despite GHD, some patients grow normally or excessively, which has been recognized as growth without GH (GWGH). Since hyperinsulinemia is highly associated with the patients with GWGH, it has been considered to play an important role for promoting linear growth. However, the causes of hyperinsulinemia associated with GWGH and the mechanisms of GWGH remain elusive. The data to date collectively suggest that the location of brain tumors and/or the mode of surgery, insulin resistance associated with obesity, insulin-like growth factor (IGF)-I, IGF binding protein (IGFBP)-1 and −3, leptin and prolactin (PRL) may contribute to the regulation of insulin secretion in patients with GWGH. Besides its metabolic effects, insulin exerts the diverse effects as a growth factor, including proliferation and differentiation of osteoblasts, leading to acceleration of linear growth. Interaction between insulin- and IGF-I-induced signaling pathways and of insulin with other hormonal factors such as leptin or PRL may play a crucial role for promoting linear growth in patients with GWGH. Despite normal or excessive linear growth, patients with GWGH still have metabolic abnormalities and retarded bone maturation. It remains elusive whether GH replacement therapy solves these problems and enables the patients to reach normal height in adulthood. Better understanding for the mechanisms of GWGH is essential to improve the quality of life of patients with GWGH. Because of a lack of accumulating data, further studies would be necessary to clarify the clinical characteristics and the mechanisms of GWGH in more detail in the future.

In the study presented here, the iron status in the kidney in passive Heymann nephritis, a complement-dependent model of membranous nephropathy, was examined. To examine whether the effect of immune injury on iron status has a pathogenic role, the effect of an iron-deficient diet was also determined. Injection of the anti-Fx1A antibody (10 mg/100 g body wt) in Sprague-Dawley rats resulted in no change in the serum iron level, a marked increase in the urinary excretion rate of iron, a marked increase in non-heme iron content of kidney cortex, and a marked increase in the non-heme iron level in tubules. These increases in iron were prevented by feeding the rats an iron-deficient diet. In the rats fed a normal iron diet and injected with anti-Fx1A-lgG, there was no significant change in the non-heme iron level in glomeruli. However, an iron-deficient diet resulted in a significant decrease in the non-heme iron level in glomeruli, compared with its respective control. In addition, an iron-deficient diet significantly reduced urinary protein excretion rate (Day 5: iron-replete, 68 +/- 12 mg/24 h, N = 12; iron-deficient, 36 +/- 11, N = 10, P < 0.05) in the complement-dependent immune phase of the glomerular injury. Taken together, these data indicate a marked alteration in the iron status in the kidney and suggest an important role of iron in glomerular injury of passive Heymann nephritis.

Hypoxia/reoxygenation is an important cause of tissue injury in a variety of organs and is classically considered to be a necrotic form of cell death. We examined the role of endonuclease activation, considered a characteristic feature of apoptosis, in hypoxia/reoxygenation injury. We demonstrate that subjecting rat renal proximal tubules to hypoxia/reoxygenation results in DNA strand breaks and DNA fragmentation (both by an in situ technique and by agarose gel electrophoresis), which precedes cell death. Hypoxia/reoxygenation resulted in an increase in DNA-degrading activity with an apparent molecular mass of 15 kDa on a substrate gel. This DNA-degrading activity was entirely calcium dependent and was blocked by the endonuclease inhibitor aurintricarboxylic acid. The protein extract from tubules subjected to hypoxia/reoxygenation cleaved intact nuclear DNA obtained from normal proximal tubules into small fragments, which further supports the presence of endonuclease activity. Despite unequivocal evidence of endonuclease activation, the morphologic features of apoptosis, including chromatin condensation, were not observed by light and electron microscopy. Endonuclease inhibitors, aurintricarboxylic acid and Evans blue, provided complete protection against DNA damage induced by hypoxia/reoxygenation but only partial protection against cell death. Taken together, our data provide strong evidence for a role of endonuclease activation as an early event, which is entirely responsible for the DNA damage and partially responsible for the cell death that occurs during hypoxia/reoxygenation injury. Our data also indicate that in hypoxia/reoxygenation injury endonuclease activation and DNA fragmentation occur without the morphological features of apoptosis.

Sequential neuroimaging before and after seizures has not been reported in patients with nephrotic syndrome and recurrent posterior reversible encephalopathy syndrome (PRES). We report a 13-year-old nephrotic female patient with recurrent PRES during and after cessation of cyclosporine A (CyA). She had headache, visual disturbance and acute hypertension, followed by seizures. The brain magnetic resonance imaging (MRI) before seizures revealed a high signal intensity area on fluid-attenuated inversion recovery and diffusion-weighted images and a low signal intensity area on T1-weighted images in bilateral parieto-occipital and left temporal lobes. Cessation of CyA resulted in clinical improvement. The follow-up MRI 2 months after the initial episode showed a complete resolution. Six months later, she had similar symptoms, edema, severe hypoalbuminemia, renal insufficiency, and acute pancreatitis before seizures. The brain MRI after seizures showed similar abnormalities in the same regions, which completely resolved 2 months later. Recurrence of acute severe hypertension, nephrotic state (edema/ hypoalbuminemia), and renal insufficiency may lead to recurrent PRES and thus early treatment of trigger factors, especially of hypertension, is important to reduce the episodes of PRES.

It remains elusive what factors affect posterior reversible encephalopathy syndrome (PRES). Eleven PRES children, all with acute glomerulonephritis, Alport syndrome, and lupus nephritis, 5 with nephrosis, and 3 renal transplant recipients, were studied. PRES recurred in 1 patient. Neurological symptoms were graded as 1: mild (headache, nausea/vomiting, or tremor), 2: moderate (vision change), and 3: severe (mental dysfunction, cerebellar symptoms, seizures, recurrence of seizures, and coma). Magnetic resonance imaging was graded as 1: subtle change, 2: abnormal large areas, and 3: complete involvement of the regions. The common symptoms were seizures (100%), headache (82%), nausea/vomiting (73%), coma (55%), and vision change (46%). Seizures recurred in 7 (64%). All but one (91%) developed hypertension and 7 (64%) received calcineurin inhibitors (CNI). Edema occurred in 7 (64%) and renal insufficiency/end-stage renal disease (ESRD) in 4 (36%). Seizures recurred frequently in younger patients. Symptoms were severe in girls. Duration or severity of the condition with predisposing factors (hypertension, CNI, nephrosis or renal insufficiency/ERSD) did not make a difference in the symptoms and neuroimaging. Two patients developed chronic epilepsy. Age and gender may affect PRES symptoms. Our results are limited by small sample size and should be determined using larger numbers of patients.

Iron has been shown to be important in ischaemic, immune and toxic forms of tissue injury in various organs. Although it is generally accepted that iron participates in the generation of powerful oxidant species (e.g. hydroxyl radicals) there has not been any direct evidence that iron capable of catalysing free-radical reactions is increased in tissues in these models of injury. In the present study we demonstrate that ischaemia/reperfusion injury to the kidney results in no significant change in total, nonhaem or ferritin iron levels, but there is a marked and specific increase in bleomycin-detectable iron (capable of catalysing free-radical reactions) in the kidney. The increase in bleomycin-detectable iron is observed only after reperfusion but not during the ischaemic period. In a separate study we demonstrate that despite a drastic reduction in the iron content in the kidney, as a result of feeding an iron-deficient diet, there is a similar and a marked increase in the bleomycin-detectable iron in kidneys accompanied by a lack of protection against ischaemia/reperfusion injury.

Both reactive oxygen metabolites and calcium have been implicated in ischemic and toxic renal tubular cell injury. However, the role of calcium in oxidant injury to renal tubular cells has not been previously examined. In the present study we examined the role of intracellular free Ca2+ ([Ca2+]i) in H2O2-mediated injury to LLC-PK1 cells, a renal tubular epithelial cell line. H2O2 induced a significant rise in [Ca2+]i within 1 min after exposure of cells to 5 mM H2O2, with a sustained rise in [Ca2+]i during the course of experiments, reaching a value of 1.3 microM at 60 min (n = 10). The rise in [Ca2+]i preceded sublethal cell injury as measured by [3H]adenine release or irreversible cell injury as determined by trypan blue exclusion. Buffering [Ca2+]i with quin-2 (50 microM) and 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA, 50 microM) was highly protective against the H2O2-induced cell injury. For example, at 120 min after exposure of cells to 5 mM H2O2, irreversible cell injury was reduced from 45 +/- 8 to 9 +/- 1% (n = 3) by quin-2. The acetoxymethyl ester of quin-2 (quin-2/AM) and BAPTA/AM did not interfere with the trypan blue exclusion assay or scavenge H2O2. Preventing mobilization of Ca2+ from intracellular storage sites using 8-(N,N-dimethylamino)octyl 3,4,5-trimethoxybenzoate hydrochloride (TMB-8, 10(-4) M) significantly reduced the rise in [Ca2+]i and thus prevented H2O2-mediated cytotoxicity to LLC-PK1 cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Little information is available on the effect of second cytotoxic therapy in steroid-dependent children with minimal change nephrotic syndrome (MCNS).Response to second cytotoxic therapy and side effects were reviewed in 33 steroid-dependent and cyclophosphamide-resistant children with MCNS who received chlorambucil (n=11, group 1) or cyclophosphamide (n=22, group 2).Age at onset of nephrosis, beginning of first and second therapy, sex ratio, duration of nephrosis before first cytotoxic therapy, interval between first and second cytotoxic therapy, number of relapses, cumulative doses of steroids and length of remission off steroids before second therapy were similar between groups. Four patients (36.4%, p0.05) in group 1 remained in remission for a median 34.0 months, whereas only 1 patient (4.5%) in group 2 did for 53.0 months. Two patients in group 1 and 1 patient in group 2 became infrequent relapsers. Total number of nonrelapsers and infrequent relapsers was higher in group 1 (54.5%, p0.05) than in group 2 (9.1%). Number of relapses and cumulative doses of steroids were reduced and length of remission off steroids was longer in group 1 than in group 2 (p0.05). There was no difference between groups in frequency of side effects, and none had serious toxicity. However, the short period of follow-up in our study does not exclude the risk of azoospermia.Our data suggest a superior effect of chlorambucil over cyclophosphamide in steroid-dependent and cyclophosphamide-resistant children with MCNS. A future randomized controlled clinical trial is required to confirm our findings.

Receptor-mediated increase in cytosolic calcium in LLC-PK 1 cells by platelet activating factor and thromboxane A 2 . Several studies indicate an important role of platelet activating factor (PAF) and thromboxane A 2 (TXA 2 ) in glomerular pathophysiology. However, the potential role of PAF or TXA 2 in renal tubular pathophysiology has received little attention, and the presence of functional receptors for these autacoids in renal tubular epithelium has not been previously studied. We examined the effects of PAF and the TXA 2 analogue, ONO11113, on the cytosolic free calcium concentration ([Ca 2+ ] i ) in cultured LLC-PK 1 , cell line using a fluorescent probe, fura-2. In these cells, the addition of PAF or ONO11113 caused a significant increment in [Ca 2+ ] i in a dose-dependent manner: both agonists (10 -7 M) increased [Ca 2+ ] i from 148 ± 16 to 288 ± 39 nM and from 130 ± 8 to 240 ± 18 nM, with the values of EC 50 for PAF and ONO11113 being 17 ± 4 and 17 ± 2 nM, respectively. These effects were both rapid and transient, returning to baseline in two minutes. The effect of PAF was selectively blocked by PAF receptor antagonist BN50730, but not by TXA 2 receptor antagonist L657925. Similarly ONO1113 response was abolished by L657925, but not by BN50730. PAF- or ONO11113-challenged cells did not respond to a second addition of the same agent and showed heterologous desensitization to the other agonist. The initial peaks of [Ca 2+ ] i as well as the sustained elevations in [Ca 2+ ] i induced by PAF or ONO11113 were reduced following the chelation of extracellular Ca 2+ by 10 mM ethylene glycol-bis(β-aminomethyl ether)-N,N,N′,N′-tetraacetic acid (EGTA). In the absence of extracellular Ca 2+ 8-(N,N-dimethylamino)octyl 3,4,5-trimethoxybenzoate hydrochloride (TMB-8) (which has extensively been used to study the contribution of Ca 2+ released from intracellular storage sites in the increase in [Ca 2+ ] i ), blocked the increment in [Ca 2+ ] i induced by PAF or ONO1113. These results indicate that LLC-PK i cells express discrete receptors for PAF and TXA 2 that are coupled to an increase in [Ca 2+ ] i through mobilization of calcium from both intracellular storage sites and extracellular milieu, and suggest the possible importance of PAF and TXA 2 in tubular pathophysiology.

Effect of corticosteroids (steroids) on some hemostatic parameters was serially studied in 23 children with minimal change nephrotic syndrome (MCNS). Increased platelet count, erythrocyte sedimentation rate (ESR), cholesterol, fibrinogen, fibrin(ogen) degradation products (FDP), alpha 2-macroglobulin (alpha 2M), alpha 2-antiplasmin (alpha 2AP) and protein C, and reduced antithrombin III (ATIII) and plasminogen (Plg) were noted in relapse before steroid therapy began. With institution of oral prednisolone, FDP started to fall, and platelet count, cholesterol, alpha 2M, ATIII, Plg, alpha 2AP and protein C started to increase despite unchanged nephrotic state from that before the therapy. In remission induced by prednisolone, platelet count, cholesterol, alpha 2M, ATIII, Plg, alpha 2AP and protein C were still increased, but normalized off therapy. ESR, fibrinogen, FDP, alpha 2M and protein C correlated inversely with serum albumin and directly with cholesterol and urine protein excretion. In contrast, ATIII and Plg correlated directly with serum albumin and inversely with cholesterol and urine protein excretion. A direct correlation was only noted between alpha 2AP and the dose of prednisolone. The data indicate that steroids appear to be a thrombogenic factor by accerelating thrombocytosis and hyperlipidemia, and by reducing plasma fibrinolysis in children with MCNS.

Ceramide is known to play a role in the cell signaling pathway involved in apoptosis. Most studies suggest that enhanced ceramide generation is the result of hydrolysis of sphingomyelin by sphingomyelinases. However, the role of ceramide synthase in enhanced ceramide generation has not been previously examined in hypoxia-reoxygenation injury. In the present study, we demonstrated that 60-min hypoxia of rat renal tubular epithelial NRK-52E cells in a gas chamber with 95% N2-5% CO2with glucose deprivation resulted in a significant increase in ceramide generation. The ceramide level further increased after reoxygenation for 60 min. Exposure of cells to hypoxia-reoxygenation resulted in a significant increase in ceramide synthase activity without any significant change in acid or neutral sphingomyelinase. The hypoxia-reoxygenation of NRK-52E cells was also associated with the release of endonuclease G (EndoG) from mitochondria to cytoplasm measured by Western blot analysis and endonuclease activity assay. It further led to the fragmentation of DNA and cell death. A specific inhibitor of ceramide synthase, fumonisin B1 (50 μM), suppressed hypoxia-reoxygenation-induced ceramide generation and provided protection against hypoxia-reoxygenation-induced EndoG release, DNA fragmentation, and cell death. Taken together, our data suggest that hypoxia-reoxygenation results in an activation of ceramide synthase rather than sphingomyelinase and that ceramide synthase-dependent ceramide generation is a key modulator of EndoG-mediated cytotoxicity in hypoxia-reoxygenation injury to renal tubular epithelial cells.

Sir, Here, we report a neonate with severe oligo-anuric renal failure during multi-organ failure who survived with prolonged renal replacement therapy. A female neonate, born at a gestational age of 39 weeks and 3 days, weighing 2780 gram, presented cyanosis on Day 15. She developed anuria and respiratory arrest, requiring mechanical ventilation. Blood pressure was 39/24 mmHg. She was diagnosed as having interrupted aortic arch, requiring surgery (Figure 1). Serum creatinine increased from 0.34 to 1.26 mg/dL. Continuous-flow peritoneal dialysis (PD), using two catheters for dialysate infusion and drainage simultaneously, was started. She had septicemia, which was controlled with antibiotics. After surgery, chylous effusion occurred in the thorax, resulting in pleural effusion and edema. At ∼2 months, she passed small volumes of urine output with renal and dialytic clearances of 0.98 and 11.45 mL/min/1.73 m2, respectively. Ligation of the thoracic duct was performed at 2.5 months. Overfluid status continued till 3 months, requiring PD and mechanical ventilation. Fig. 1. Course of the illness in the neonate. Cdial, dialytic clearance; Cr, creatinine; Crenal, renal clearance; Inf, influenza A virus infection; PN, peritonitis; RS, respiratory syncytial virus infection; RV, rotavirus infection; UV, urine volume. Because of frequent vomiting, she was fed with an intestinal tube at 4.5 months, resulting in severe diarrhea for 1 month. She remained anuric at 5 months despite decreased serum creatinine (1.36 mg/dL) due to malnutrition. Renal clearance was 1.68 mL/min/1.73 m2 at 6 months when urine output was redetected. She had episodes of peritonitis and virus infections, resulting in pleural effusion, requiring antibiotics, supportive therapy and PD. Renal clearance increased to 8.44 mL/min/1.73 m2 at 8 months. Urine output increased with serum creatinine of 0.81–1.2 mg/dL and renal clearance of 10.4 mL/min/1.73 m2 at 10 months, representing almost 50% of total clearance. Dialysis was stopped 1 year after surgery. Her growth and development are normal with glomerular filtration rate of 24.7 mL/min/1.73 m2. Prolonged oligo-anuria correlates with the final outcome [1]. Renal function recovered after 6–14 months of oliguria in two children with hemolytic uremic syndrome (HUS), in whom plasma infusion prolonged acute renal failure (ARF) [2], and after 23 days of oliguria in an infant with HUS, at the age of 23 weeks [3]. Younger age is another poor prognostic factor of ARF [4]. Neonates have a decreased number and function of nephron, resulting in severe renal insult and poor outcome [5]. ARF occurs in 8% of neonates in the intensive care unit, and its mortality rate is 48% [4], depending on the underlying disease and prognostic factors, including respiratory support, hypotension, cardiac disorders, surgery, oliguria/anuria, need for vasopressor drugs or dialysis, sepsis or multi-organ failure [1]. Despite these factors, the renal function of our patient returned to an extent that allowed cessation of dialysis after many months although PD might have been stopped late. Our patient still has significant chronic kidney disease and will require renal replacement therapy again in the future. Our observation suggests that neonates with severe oligo-anuric renal failure during multi-organ failure may survive with prolonged renal replacement therapy.

It has been generally accepted that a catastrophic breakdown of regulated cellular homeostasis, known as necrosis, is the mode of cellular injury in various forms of acute renal failure. One of the major advances in our understanding of cell death has been the recognition that the pathways traditionally associated with apoptosis as described in the landmark study by Kerr, Wyllie, and Currie in 1972 may be very critical in the form of cell injury associated with necrosis. The pathway that is followed by the cell varies with both nature and severity of insults and may evolve from an apoptotic to a necrotic form of cell death. It is also likely that there are some common pathways that are shared and regulated in the two modes of cell death. In this review, we first describe evidence for the role of apoptotic pathways in ischemic acute renal failure, and then consider the potential mechanisms that may participate in this model of acute renal tubular injury. We then summarize the current information of apoptotic pathways related to other common causes of acute renal failure including endotoxin-induced, toxic acute renal failure and transplant rejection. A better understanding of the mechanisms of apoptosis could lead to safer and more specific therapeutic interventions for acute renal failure.

Over the last decade, there is accumulating evidence for a role of reactive oxygen metabolites in the pathogenesis of a variety of renal diseases, including gentamicin, glycerol, cisplatin, and cyclosporine A models of toxic acute renal failure. Gentamicin has been shown both in in vitro and in vivo studies to enhance the generation of reactive oxygen metabolites. Iron is important in models of tissue injury, presumably because it is capable of catalyzing free-radical formation. Gentamicin has been shown to cause release of iron from renal cortical mitochondria. Scavengers of reactive oxygen metabolites as well as iron chelators provide protection in gentamicin-induced nephrotoxicity. In glycerol-induced acute renal failure, an animal model of rhabdomyolysis, there is enhanced generation of hydrogen peroxide, and scavengers of reactive oxygen metabolites and iron chelators provide protection. Although the dogma is that the myoglobin is the source of iron, recent studies suggest that cytochrome P450 may be an important source of iron in this model. In addition, there are marked alterations in antioxidant defenses, such as glutathione, as well as changes in heme oxygenase. Several recent in vitro and in vivo studies indicate an important role of reactive oxygen metabolites in cisplatin-induced nephrotoxicity. Thus, catalytic iron is increased both in vitro and in vivo by cisplatin, and iron chelators as well as hydroxyl radical scavengers have been shown to be protective. Recent studies indicate that cytochrome P450 may also be an important source of the catalytic iron in cisplatin nephrotoxicity. Cyclosporine A has been shown to enhance generation of hydrogen peroxide in vitro and enhance lipid peroxidation in vitro and in vivo. Antioxidants have been shown to be protective in cyclosporine A nephrotoxicity. This collective body of evidence suggests an important role for reactive oxygen metabolites in toxic acute renal failure and may provide therapeutic opportunities of preventing or treating acute renal failure in humans.

Role of cytochrome P-450 as a source of catalytic iron in cisplatin-induced nephrotoxicity. Background Iron plays a role in free radical-mediated tissue injury, including cisplatin-induced nephrotoxicity. However, the source of iron (catalyzing free radical reactions) is not known. We examined the role of cytochrome P-450 as a source of catalytic iron in cisplatin-induced nephrotoxicity both in vivo and in vitro. Methods Cisplatin-induced acute renal failure was produced in rats by intraperitoneal injection of cisplatin (10 mg/kg body wt). Piperonyl butoxide, a cytochrome P-450 inhibitor, was administered intraperitoneally (400 mg/kg body wt twice at 48-hr intervals) prior to cisplatin injection. The effects of cisplatin in the absence or presence of piperonyl butoxide on the belomycin-detectable iron, cytochrome P-450 content in the kidney, and renal functional and histological changes were evaluated. In an in vitro study, the effect of cytochrome P-450 inhibitors, cimetidine or piperonyl butoxide, on cisplatin-induced cytotoxicity and catalytic iron release from LLC-PK1 cells was examined. Results In cisplatin-treated rats, there was a marked decrease in the cytochrome P-450 content specifically in the kidney, accompanied by increased bleomycin-detectable iron content in the kidney. Piperonyl butoxide prevented cisplatin-induced loss of cytochrome P-450 as well as the increase of bleomycin-detectable iron in the kidney, along with both functional and histological protection. Both cimetidine and piperonyl butoxide prevented cisplatin-induced increase in bleomycin-detectable iron and cytotoxicity in LLC-PK1 cells. Treatment of cimetidine did not affect cellular uptake of cisplatin. Conclusion Cytochrome P-450, a group of heme proteins, may serve as a significant source of catalytic iron in cisplatin-induced nephrotoxicity.