Usefulness of mizoribine administration in children with frequently relapsing nephrotic syndrome, and the relationship between pharmacokinetic parameters and efficacy: a multicenter prospective cohort study in China.

BACKGROUND: Mizoribine (MZR) is an immunosuppressant used to treat adult nephropathy. There is little experience with the drug in treating Chinese children with frequently relapsing nephrotic syndrome (FRNS). We investigated the efficacy and safety for treating MZR with FRNS. Furthermore, the relationship between efficacy and serum concentration was investigated. METHODS: A prospective multicenter observational 12-month study was performed for evaluating the usefulness of MZR with FRNS. Serum MZR concentration was measured, and the relationships between pharmacokinetic parameters (Cmax, AUC), number of relapses, and urinary protein were evaluated. RESULTS: Eighty-two pediatric patients from four hospitals were treated with MZR and prednisone. MZR treatment significantly reduced the number of relapses and steroid doses. A correlation between pharmacokinetic parameters and relapses was observed, which fits well with the sigmoidal Emax model. Even in the relationship between pharmacokinetic parameters and urinary proteins, it was recognized that there was a threshold in the pharmacokinetic parameters for the therapeutic effect similar to the results obtained with the sigmoidal Emax model. Eleven patients (13.4%) experienced mild adverse events. CONCLUSIONS: MZR therapy was effective in reducing the number of relapses and steroid doses. No severe adverse reactions were observed. Therapeutically effective serum concentrations were estimated to be Cmax ≥ about 2 µg/mL or AUC ≥ about 10 µg h/mL. MZR and steroid treatment were effective and safe for pediatric FRNS.

MicroRNA­106b regulates skeletal muscle insulin sensitivity and glucose homeostasis by targeting mitofusion­2.

MicroRNA­106b (miR­106b) is reported to be closely associated with skeletal muscle insulin resistance. The present study further investigated the role of miR­106b in skeletal muscle insulin sensitivity and glucose homeostasis in vivo. Mice were randomly divided into 4 groups and infected with lentivirus expressing miR­106b (miR­106b mice), miR­106b sponge (miR­106b inhibition mice) or the corresponding empty vectors. Mitofusion­2 (Mfn2) protein expression levels and glucose transporter (Glut)­4 protein translocation were significantly reduced in the muscle of miR­106b mice, whereas they were unaffected in miR­106b inhibition mice. miR­106b mice had significantly increased blood glucose levels following 12 h of fasting and impaired glucose tolerance, whereas miR­106b inhibition mice had no significant alterations in fasting blood glucose levels and glucose tolerance. In vitro, the suppressive effect of miR­106b on glucose uptake and Glut4 translocation was completely inhibited in C2C12 myotubes infected with Mfn2 plasmids. Following treatment of C2C12 myotubes with Mfn2 small interfering RNA, miR­106b inhibition consistently increased Mfn2 protein levels and improved glucose uptake and Glut4 translocation. These results indicated that miR­106b targeted Mfn2 and regulated skeletal muscle insulin sensitivity and glucose tolerance. Therefore, increased miR­106b expression may be a potential mechanism underlying insulin resistance and type 2 diabetes.

Silencing miR-106b improves palmitic acid-induced mitochondrial dysfunction and insulin resistance in skeletal myocytes.

MicroRNA­106b (miR­106b) is reported to correlate closely with skeletal muscle insulin resistance. In the current study the effect of miR­106b on palmitic acid (PA)­induced mitochondrial dysfunction and insulin resistance was investigated in C2C12 myotubes via the silencing of miR­106b. MiR­106b expression was increased under PA treatment, while miR­106b loss of function improved insulin sensitivity by upregulating its target mitofusin­2 (Mfn2) in C2C12 myocytes. Furthermore, miR­106b loss of function partly improved mitochondrial morphological lesions and increased the levels of mitochondial DNA and intracellular adenosine triphosphate that had been impaired by PA exposure in C2C12 myocytes. MiR­106b loss of function attenuated the levels of intracellular reactive oxygen species (ROS), and upregulated the expression levels of the estrogen­related receptor (ERR)­α/peroxisome proliferative activated receptor γ coactivator (PGC)­1α/Mfn2 axis under PA exposure. In addition, miR­106b negatively regulated skeletal muscle mitochondrial function and insulin sensitivity under PA­induced insulin resistance by targeting Mfn2, which may be associated with reduced ROS and upregulation of the ERR­α/PGC­1α/Mfn2 axis.

MicroRNA-106b induces mitochondrial dysfunction and insulin resistance in C2C12 myotubes by targeting mitofusin-2.

MicroRNA-106b (miR-106b) is reported to correlate closely with skeletal muscle insulin resistance and type 2 diabetes. The aim of this study was to identify an mRNA targeted by miR-106b which regulates skeletal muscle insulin sensitivity. MiR-106b was found to target the 3' untranslated region (3' UTR) of mitofusin-2 (Mfn2) through miR-106b binding sites and to downregulate Mfn2 protein abundance at the post-transcriptional level by luciferase activity assay combined with mutational analysis and immunoblotting. Overexpression of miR-106b resulted in mitochondrial dysfunction and insulin resistance in C2C12 myotubes. MiR-106b was increased in insulin-resistant cultured C2C12 myotubes induced by TNF-α, and accompanied by increasing Mfn2 level, miR-106b loss of function improved mitochondrial function and insulin sensitivity impaired by TNF-α in C2C12 myotubes. In addition, both overexpression and downregulation of miR-106b upregulated peroxisome proliferator-activated receptor gamma coactivator (PGC)-1α and estrogen-related receptor (ERR)-α expression. MiR-106b targeted Mfn2 and regulated skeletal muscle mitochondrial function and insulin sensitivity. Therefor, Inhibition of miR-106b may be a potential new strategy for treating insulin resistance and type 2 diabetes.

[Nephrotic syndrome complicated with intracranial venous thrombosis treated with urokinase: report of 5 cases].

OBJECTIVE: To explore the effect of urokinase and low molecular weight heparin in children with nephrotic syndrome complicated with intracranial venous thrombosis. METHODS: Urokinase and low molecular weight heparin were administered to the 5 patients intravenously. The initial dose of urokinase was 2000 - 4000 U/(kg.d), the initial pulse dose was 20 000 - 40 000 U given within 15 - 30 minutes, and the left was infused by using a pump, from the second day 2000 U/(kg.d) urokinase was infused daily for 3 to 7 days. During the treatment thrombin time (TT), activated partial thromboplastin time (APTT) were tested 3 times every week, with particular attention to bleeding. Low molecular weight heparin 100 - 120 AXaIU/kg, 1 or 2 times per day was hypodermally injected for a course of two weeks. Anti-platelet drugs: long-term oral administration of dipyridamole 3 - 5 mg/(kg.d) was applied 2 - 3 times every day for 3 months. RESULTS: The clinical symptoms disappeared after one month of the combined therapy of urokinase, low molecular weight heparin and dipyridamole in 5 cases of nephrotic syndrome complicated with intracranial venous thrombosis in children, the plasma viscosity returned to normal in 1 month, activated partial thromboplastin time, prothrombin time, fibrinogen degradation products returned to normal in 1 to 2 months, venous thrombosis disappeared after 1 to 3 months in head CT or MRI examination, showing the cerebral venous sinus thrombosis complete recanalization without relapse cases in follow-up. CONCLUSION: The early application of urokinase and low molecular heparin and anti-platelet coagulation drugs was effective. The early diagnosis, treatment and prevention of intracranial vein thrombosis in patients with nephrotic syndrome is important.

[Clinical and pathological study of 47 cases with Alport syndrome].

OBJECTIVE: To analyze the clinical and pathological features of children with Alport syndrome (AS). METHODS: A series of 47 patients with AS from unrelated families hospitalized from Jan. 1990 to Jan. 2007 were involved in this study. The clinical and histopathological data were collected and analyzed. RESULTS: Of the 47 cases, 32 were male and 15 female, M/F: 2.1:1. The patient's age ranged from 15 months to 13 years, mean 9 years. Thirty-nine of the 47 cases had positive family history, X-linked dominant inheritance AS was diagnosed in 37 cases, autosomal recessive inheritance AS in 2 cases. Gross hematuria or microscopic hematuria were found in 59.3% of the cases as the first manifestations, while 29.8% showed edema or proteinuria. The major clinical manifestations were isolated hematuria (23.4%), hematuria and proteinuria (36.2%), nephrotic syndrome (29.8%), and renal failure (10.6%). Hematuria and proteinuria existed in all the cases, while only 7 to 13 years children had nephrotic syndrome and renal failure. Of the 47 patients, 33 (70.2%) showed mesangial proliferative glomerulonephritis (MsPGN) under the light microscope, 13 (27.6%) focal segmental glomerulosclerosis (FSGS), 1 (2.1%) membrane proliferative glomerulonephritis (MPGN). For immunofluorescence, there was IgM (40.4%) as the dominant deposition in 19 patients, IgA in 9 (19.1%), IgG in 9 (19.1%), and 10 (21.4%) were negative. Thirty-nine cases showed typical glomerular basement membrane (GBM) pathological changes under electron microscope, while thin basement membrane in 8 cases; 46 showed abnormal skin and/or renal alpha-chain distribution. CONCLUSION: For Alport syndrome, number of male patients was higher than that of female patients. There was a significant difference among different age groups. Hematuria might be present throughout the course, while urine protein increases gradually. MsPGN was the dominant pathological change. The GBM pathological changes in younger children is not typical, so the immunofluorescence test of alpha-chain in collagen IV should be used as an important diagnostic method.

[Cyclosporin A treatment of 83 children with nephrotic syndrome of different pathological types].

OBJECTIVE: To evaluate the efficacy of cyclosporin A (CyA) therapy in 83 children with nephrotic syndrome of different pathological types. METHODS: Eighty-three children enrolled in this study were all hospitalized children with idiopathic nephrotic syndrome, aged 3 to 14 yrs (average 8.3 yrs) and included 52 males and 31 females. There were 35 cases with steroid-dependent, 17 with steroid resistant and 26 with frequent relapses. CyA was given to each patient with dosage of 5 mg/(kg.d) during the corticosteroid was diminished. The renwal biopsy was performed in all patients before the administration of CyA. The duration of CyA therapy lasted for about 3 to 6 months. The plasma concentration of CyA was monitored. RESULTS: Eighty-three children with nephrotic syndrome of different pathological types were treated with CyA, including 42 cases of minimal change nephrotic syndrome (MCNS), 31 cases of mesangioproliferative glomerulonephritis (MsPGN), 5 cases of membranoproliferative glomerulonephritis (MPGN) and 4 cases of focal segmental glomerular sclerosis (FSGS). All the 83 patients tolerated well to the CyA treatment. Forty-five cases got complete remission, 23 partial remission, 15 cases no change after one month treatment with CyA in the hospital. The overall response rate was 82%. Patients with different renal pathological types showed different responses. Among them, MCNS and MsPGN exhibited the best response rates of 86% and 84%, respectively; MPGN cases showed a lower response rate and FSGS cases showed the lowest rate. The response time was 7 to 45 days. The blood concentration of CyA was monitored for 1 week and 2 weeks after the drug was given. The effective drug concentration was maintained at 100 to 200 microg/L, and the course lasted for 3 to 6 months. During the follow-up of 83 cases, in 17 of 68 cases the disease relapsed when therapy was tapered or discontinued. The relapse rate was 25%. The results indicated that CyA would be effective to the relapsed cases. The serum creatinine increased temporarily after administration of CyA in 5 cases, N-acetyl-beta-D-glucosaminidase (NAG) in 8 cases and eventually reached the normal range after the adjustment of dosage. The side effects included anorexia, nausea, vomiting and so on. CONCLUSION: CyA is one of the effective substitutes for the treatment of nephrotic syndrome, especially for the cases with MCNS and MsPGN. And CyA could control refractory nephrotic syndrome effectively and rapidly. The clinical effect was related to the blood concentration of CyA and pathological types.