[Show abstract][Hide abstract] ABSTRACT: 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.
Preview · Article · Mar 2015 · International Journal of Molecular Sciences
[Show abstract][Hide abstract] ABSTRACT: 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) < 12 g/dL, ferritin < 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 < 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.
[Show abstract][Hide abstract] ABSTRACT: 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.
No preview · Article · Jun 2014 · Pediatric Transplantation
[Show abstract][Hide abstract] ABSTRACT: 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.
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 <15.0 ng/ml) and high ferritin groups (7; serum ferritin of ≥15.0 ng/ml). The response of hepcidin-25 to rhEPO and the effect of rhEPO on anemia were compared between the groups.
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 (<5.0 ng/ml) in the low ferritin group, but rose at 6-9 h after rhEPO in the high ferritin group. Serum transferrin levels were similar, and CRP and IL-6 were normal in both groups. Hb tended to increase in the low ferritin group, but it significantly decreased in the high ferritin group after rhEPO.
Regulation of hepcidin-25 by rhEPO may be dependent on ferritin, affecting the response to rhEPO in HD patients.
[Show abstract][Hide abstract] ABSTRACT: 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.
[Show abstract][Hide abstract] ABSTRACT: 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.
No preview · Article · Mar 2013 · Molecular and Cellular Biochemistry
[Show abstract][Hide abstract] ABSTRACT: 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.
No preview · Article · Nov 2012 · Clinical nephrology
[Show abstract][Hide abstract] ABSTRACT: Oral iron administration (OIA) is little benefit, and I.V. iron injection (IVI) is recommended. IVI increases high serum ferritin (ferr) levels, increaseing serum hepcidin-25(hepc) levels, which inhibits intestinal iron absorption. In a state of low hepc levels, intestinal iron absorption can be well preserved. We examined whether smaller or normal MCV affects the therapeutic effect of OIA in HD patients with low hepc levels. Serum hepc were measured in 66 patients on HD. Of these, oral iron was immediately administered in 14 cases who had low serum hepc levels (<14ng/ml). Hb was measured before and 8 weeks after OIA. Serum levels of ferr, hepc, MCV and Hb were measured before starting HD. A correlation between the based MCV and improvement of Hb was analyzed. Mean hepc levels were 14.0± 22.6 ng/mL in 66 cases. Serum levels of hepc correlated with ferr (r=0.46, p<0.01). The values for MCV were less than 88fL in 6 cases (LMCV group, HD duration, 8.7±4.4 years, and the OIA dose, 50 mg/day). The remaining 8 cases showed normal MCV (96.6± 5.7fL) (NMCV group, 7.3±4.6 years, 62.5mg/day). In LMCV group, Hb increased from 9.4±0.4g/dL to 11.2±3.5g/dL. In NMCV group, they increased from 10.3±2.1g/dL to 11.1±2.2g/dL. An increment in Hb was significantly greater in LMCV group (3.1±1.2g/dL, p<0.05) than that in NMCV group (0.8±2.2g/dL). There was no difference between L and N MCV groups in Hb (9.4±0.4, vs. 10.3±2.1 g/dL), and serum levels of ferr (7.8±4.3, vs. 13.9±10.0ng/mL) and hepc (4.6±6.6, vs. 3.7 ± 4.0 ng/ mL). In conclusions, in a state of low hepcidin, OIA is more beneficial for anemia in HD patients with low MCV than in those with normal MCV.
[Show abstract][Hide abstract] ABSTRACT: 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.
Preview · Article · Dec 2011 · Journal of Biological Chemistry
[Show abstract][Hide abstract] ABSTRACT: It remains elusive whether there is a crosstalk between Smad and mitogen-activated protein kinases (MAPKs) and whether it regulates cyclosporine A (CyA)-induced apoptosis in renal proximal tubular cells (RPTCs).
The effect of CyA on nuclear translocation of Smad2/3 and MAPKs (measured by Western blotting or immunofluorescence) and apoptosis (determined by Hoechst 33258 staining) was examined in HK-2 cells.
CyA induced apoptosis at 24 h and nuclear translocation of phosphorylated (p)-Smad2/3 at 3 h, which was continued till 24 h. CyA enhanced the expression of p-ERK at 1 h, which was continued till 24 h, and of p-p38MAPK at 1-6 h, which returned to control level at 12 h. CyA did not affect JNK. An inhibitor of ERK, PD98059, prevented CyA-induced nuclear translocation of Smad2/3 and apoptosis. An inhibitor of p38MAPK, SB202190, deteriorated CyA-induced nuclear translocation of p-Smad2/3. Epidermal growth factor (EGF) activated ERK and p38MAPK but not JNK. EGF-induced activation of MAPKs ameliorated CyA-induced nuclear translocation of p-Smad2/3 and apoptosis. Inhibition of p38MAPK but not of ERK abolished the protective effect of EGF on CyA-induced nuclear translocation of p-Smad2/3 and apoptosis.
Crosstalk between R-Smad and p38MAPK/ERK, but not JNK differentially regulates apoptosis in CyA-induced RPTC injury.
[Show abstract][Hide abstract] ABSTRACT: 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.
No preview · Article · Aug 2011 · Pediatric Nephrology
[Show abstract][Hide abstract] ABSTRACT: 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.
[Show abstract][Hide abstract] ABSTRACT: 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.
[Show abstract][Hide abstract] ABSTRACT: Three-dimensional visualization of renal arteries has recently been established by helical contrast-enhanced multiple detector-row computed tomographical angiography (MDCTA) in adults. So far, no information is available on its use in children. We reported two children with renal artery stenosis detected by 64-channel MDCTA. The first patient probably had fibromuscular dysplasia and the other neurofibromatosis type1. The technique showed a left renal artery stenosis with a small left kidney in the first patient and a right renal artery stenosis in the second.
Conclusion: MDCTA is an accurate and noninvasive imaging technique, easily performed in children, and can be used as an alternative diagnostic modality in children with suspected renovascular hypertension.
No preview · Article · Oct 2009 · Acta Paediatrica
[Show abstract][Hide abstract] ABSTRACT: 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%, p<0.05) 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%, p<0.05) 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 (p<0.05). 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.
No preview · Article · Sep 2009 · Journal of nephrology
[Show abstract][Hide abstract] ABSTRACT: 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.
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 x 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.
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.
No preview · Article · Oct 2007 · Birth Defects Research Part A Clinical and Molecular Teratology