Rosemary extract and rosmarinic acid accelerate elastic fiber formation by increasing the expression of elastic fiber components in dermal fibroblasts.

Ultraviolet (UV)-induced skin photoaging is caused by qualitative and quantitative degradation of dermal extracellular matrix components such as collagen and elastic fibers. Elastic fibers are important for maintaining cutaneous elasticity, despite their small amount in the skin. Previously, microfibril-associated protein 4 (MFAP-4), which is downregulated in photoaging dermis, has been found to be essential for elastic fiber formation by interaction with both fibrillin-1 and elastin, which are core components of elastic fiber. In addition, enhanced cutaneous MFAP-4 expression in a human skin-xenografted murine photoaging model protects against UV-induced photodamage accompanied by the prevention of elastic fiber degradation and aggravated elasticity. We therefore hypothesized that the upregulation of MFAP-4 in dermal fibroblasts may more efficiently accelerate elastic fiber formation. We screened botanical extracts for MFAP-4 expression-promoting activity in normal human dermal fibroblasts (NHDFs). We found that rosemary extract markedly promotes early microfibril formation and mature elastic fiber formation along with a significant upregulation of not only MFAP-4 but also fibrillin-1 and elastin in NHDFs. Furthermore, rosmarinic acid, which is abundant in rosemary extract, accelerated elastic fiber formation via upregulation of transforming growth factor ß-1. This was achieved by the induction of cAMP response element-binding protein phosphorylation, demonstrating that rosmarinic acid represents one of the active ingredients in rosemary extract. Based on the findings in this study, we conclude that rosemary extract and rosmarinic acid represent promising materials that exert a preventive or ameliorative effect on skin photoaging by accelerating elastic fiber formation.

Carbon dioxide-induced decrease in extracellular pH enhances the production of extracellular matrix components by upregulating TGF-ß1 expression via CREB activation in human dermal fibroblasts.

Mild acidification caused by transcutaneous administration of carbon dioxide (CO2 ) has been reported to improve some epidermal skin impairments, such as desquamation and inflammation; however, its effects on dermal tissue remain unclear. Here, we examined the effect and mechanism of mild acidity on extracellular matrix (ECM) protein production in normal human dermal fibroblasts (NHDFs). To achieve this, the skin permeability of CO2 and its effect on intradermal pH were evaluated by treating reconstructed human skin equivalents (HSEs) with a CO2 -containing formulation. Additionally, NHDFs were cultured in a pH-adjusted medium (pH 6.5). CO2 successfully permeated HSEs and reduced the intradermal pH. Decreased extracellular pH activated CREB, upregulated TGF-ß1 expression, promoted the production of elastic and collagen fibres, and increased hyaluronan concentration in NHDFs. Additionally, the low pH-induced increase in TGF-ß1 expression was attenuated via the RNAi-mediated suppression of the expression of CREB1 and proton-sensing G protein-coupled receptors (GPCRs), including GPR4 and GPR65. Moreover, low pH-induced CREB activation was suppressed by the inhibition of the cAMP/PKA and PLC/PKC signalling pathways. Taken together, a CO2 -induced decrease in intradermal pH may promote ECM production in NHDFs via the upregulation of TGF-ß1 expression, which was mediated by the activation of the GPCR signalling pathway and CREB, indicating that CO2 could be used to treat ultraviolet radiation-induced photoaging, intrinsic ageing and ECM deterioration.

Risk factors for discontinuation of exclusive breast feeding within 1month: a retrospective cohort study in Japan.

BACKGROUND: While breastfeeding provides benefits for infants and the mother, many women either do not breastfeed or terminate breastfeeding earlier than recommended. The aim of this analysis was to identify factors associated with early discontinuation of breastfeeding in Japanese women. METHODS: This study used data from medical records of women delivering a singleton live birth between March 2017 and August 2019 in Iwase General Hospital, Fukushima Prefecture, Japan to assess cessation of breastfeeding by the 1-month postpartum appointment. Demographic (age at birth, and employment status), medical (parity, and physical and mental condition of the mother; and infant medical factors, such as sex, Apgar score, and jaundice, among other), and family factors (husband/partner, family members living at the same house, among others) in 734 women who had initiated breastfeeding during their delivery hospital stay were examined, and multiple logistic regression was used to determine significant predictors of early cessation of exclusive breastfeeding. RESULTS: Bivariate analysis revealed that women who were primipara, unmarried, exposed to secondhand smoke, and employed; those who smoked before pregnancy; and those who had asthma were more likely to discontinue exclusive breastfeeding than other women. Infant factors associated with discontinuation were lower birthweight, earlier gestational age, neonatal intensive care unit admission, treatment for jaundice, or lower weight gain. Multivariable analysis revealed that primiparity, passive smoking before pregnancy, maternal employment, and neonatal jaundice therapy were associated with discontinuation of breastfeeding. CONCLUSIONS: In particular, women whose partners smoked before pregnancy may need to be targeted for additional support for breastfeeding.

The Surprising Effect of Phenformin on Cutaneous Darkening and Characterization of Its Underlying Mechanism by a Forward Chemical Genetics Approach.

Melanin in the epidermis is known to ultimately regulate human skin pigmentation. Recently, we exploited a phenotypic-based screening system composed of ex vivo human skin cultures to search for effective materials to regulate skin pigmentation. Since a previous study reported the potent inhibitory effect of metformin on melanogenesis, we evaluated several biguanide compounds. The unexpected effect of phenformin, once used as an oral anti-diabetic drug, on cutaneous darkening motivated us to investigate its underlying mechanism utilizing a chemical genetics approach, and especially to identify alternatives to phenformin because of its risk of severe lactic acidosis. Chemical pull-down assays with phenformin-immobilized beads were performed on lysates of human epidermal keratinocytes, and subsequent mass spectrometry identified 7-dehydrocholesterol reductase (DHCR7). Consistent with this, AY9944, an inhibitor of DHCR7, was found to decrease autophagic melanosome degradation in keratinocytes and to intensely darken skin in ex vivo cultures, suggesting the involvement of cholesterol biosynthesis in the metabolism of melanosomes. Thus, our results validated the combined utilization of the phenotypic screening system and chemical genetics as a new approach to develop promising materials for brightening/lightening and/or tanning technologies.

Quantitative changes in the secretion of exosomes from keratinocytes homeostatically regulate skin pigmentation in a paracrine manner.

The content and distribution of melanin in the epidermis determines the wide variety of skin colors associated with ethnic/racial diversity. Although it was previously reported that qualitative changes in keratinocyte-derived exosomes regulate melanocyte pigmentation in vitro, their practical involvement, especially in skin color development in vivo, has remained unclear. To address this unexplained scientific concern, the correlation of epidermal exosomes isolated from human skin tissues with melanosomal protein expression levels was demonstrated in this study for the first time. After confirming the quantitative effect of human keratinocyte-derived exosomes on human melanocyte activation, even in the absence of ultraviolet B (UV-B) exposure, the impact of exosomes secreted from UV-B-irradiated keratinocytes on melanogenesis was consistently detected, which suggests their constitutive role in regulating cutaneous pigmentation. Additionally, both a specific exosome secretion inducer and a suppressor were consistently found to significantly control melanin synthesis in a co-culture system composed of keratinocytes and melanocytes as well as in an ex vivo skin culture system. These results suggest that quantitative changes, in addition to already known qualitative changes, in exosomes secreted from human epidermal keratinocytes homeostatically regulate melanogenic activity in a paracrine manner, which leads to skin color determination.

Depigmentation caused by application of the active brightening material, rhododendrol, is related to tyrosinase activity at a certain threshold.

BACKGROUND: Tyrosinase, the rate-limiting enzyme required for melanin production, has been targeted to develop active brightening/lightening materials for skin products. Unexpected depigmentation of the skin characterized with the diverse symptoms was reported in some subjects who used a tyrosinase-competitive inhibiting quasi-drug, rhododendrol. OBJECTIVE: To investigate the mechanism underlying the depigmentation caused by rhododendrol-containing cosmetics, this study was performed. METHODS: The mechanism above was examined using more than dozen of melanocytes derived from donors of different ethnic backgrounds. The RNAi technology was utilized to confirm the effect of tyrosinase to induce the cytotoxicity of rhododendrol and liquid chromatography-tandem mass spectrometry was introduced to detect rhododendrol and its metabolites in the presence of tyrosinase. RESULTS: Melanocyte damage was related to tyrosinase activity at a certain threshold. Treatment with a tyrosinase-specific siRNA was shown to dramatically rescue the rhododendrol-induced melanocyte impairment. Hydroxyl-rhododendrol was detected only in melanocytes with higher tyrosinase activity. When an equivalent amount of hydroxyl-rhododendrol was administered, cell viability was almost equally suppressed even in melanocytes with lower tyrosinase activity. CONCLUSION: The generation of a tyrosinase-catalyzed hydroxyl-metabolite is one of the causes for the diminishment of the melanocyte viability by rhododendrol.

Two children with obesity-related glomerulopathy identified in a school urinary screening program.

The incidence of obesity-related glomerulopathy (ORG) has increased over the last decade, but there have been few reports on ORG in Japanese children. Reported herein are two children with ORG identified on school urinary screening (SUS). Patient 1 was a 12-year-old boy in whom proteinuria was first detected on SUS. His body mass index (BMI) was 33.8 kg/m(2) and he had hypertension and hyperuricemia. Patient 2, a 10-year-old boy, also had proteinuria identified on SUS. His BMI was 34.8 kg/m(2) , and he had fatty liver, hyperuricemia, and hypercholesterolemia. Both were diagnosed with ORG based on obesity, proteinuria, and renal pathological findings. After treatment, including candesartan, food restriction and physical exercise, urinary protein excretion was decreased in both cases. We believe that such school urinary screening programs may be effective for the early identification and treatment of children with ORG.

5-Lipoxygenase and cysteinyl leukotriene receptor 1 regulate epidermal growth factor-induced cell migration through Tiam1 upregulation and Rac1 activation.

Cell migration is an essential step for tumor metastasis. The small GTPase Rac1 plays an important role in cell migration. Previously, we reported that epidermal growth factor (EGF) induced two waves of Rac1 activation; namely, at 5 min and 12 h after stimulation. A second wave of EGF-induced Rac1 activation was required for EGF-induced cell migration, however, the spatiotemporal regulation of the second wave of EGF-induced Rac1 activation remains largely unclear. In this study, we found that 5-lipoxygenase (5-LOX) is activated in the process of EGF-induced cell migration, and that leukotriene C4 (LTC4 ) produced by 5-LOX mediated the second wave of Rac1 activation, as well as cell migration. Furthermore, these effects caused by LTC4 were found to be blocked in the presence of the antagonist of cysteinyl leukotriene receptor 1 (CysLT1). This blockage indicates that LTC4 -mediated CysLT1 signaling regulates the second EGF-induced wave of Rac1 activation. We also found that 5-LOX inhibitors, CysLT1 antagonists and the knockdown of CysLT1 inhibited EGF-induced T cell lymphoma invasion and metastasis-inducing protein 1 (Tiam1) expression. Tiam1 expression is required for the second wave of EGF-induced Rac1 activation in A431 cells. Therefore, our results indicate that the 5-LOX/LTC4 /CysLT1 signaling pathway regulates EGF-induced cell migration by increasing Tiam1 expression, leading to a second wave of Rac1 activation. Thus, CysLT1 may serve as a new molecular target for antimetastatic therapy. In addition, the CysLT1 antagonist, montelukast, which is used clinically for allergy treatment, might have great potential as a novel type of antimetastatic agent.

Incidence and index of severity of hemolytic uremic syndrome in a 26 year period in Fukushima Prefecture, Japan.

BACKGROUND: There have been a number of reports on large outbreaks of hemolytic uremic syndrome (HUS), but there have been no long-term studies of sporadic HUS in Japan. This study therefore investigated the epidemiology and prognosis of HUS in Fukushima Prefecture over a 26 year period. METHODS: The medical records of 26 patients with HUS between 1987 and 2012 were collected. These children were divided into two groups: those with HUS following an episode of gastroenteritis, often with bloody diarrhea (D + HUS; n = 24) and those with HUS not associated with prodromal diarrhea (D-HUS; n = 2). The D + HUS group was further subdivided into group A (11 patients requiring dialysis) and group B (13 patients not requiring dialysis). The epidemiological and clinical data, as well as prognosis, were retrospectively investigated for each group. RESULTS: Approximately 90% of HUS patients belonged to the D + HUS group. In this group, the mean number of patients per year from 1987 to 1999, and from 2000 to 2012 was 0.92 ± 0.95, and 1.08 ± 0.86, respectively. On admission, lactate dehydrogenase (LDH), alanine aminotransferase (ALT), blood urea nitrogen (BUN), serum creatinine and serum fibrinogen degradation product (FDP) levels in group A were all higher than in group B. Serum albumin level and estimated glomerular filtration rate (eGFR) in group A were lower than in group B. At 6 months after the onset of HUS in the D + HUS group, renal function was normal. CONCLUSIONS: The frequency of HUS was constant from 1987 to 2012 in Fukushima. and serum LDH, ALT, BUN, creatinine, and FDP levels as well as eGFR might be risk factors for dialysis in D + HUS children.

Autophagy has a significant role in determining skin color by regulating melanosome degradation in keratinocytes.

Melanin in the epidermis determines the wide variation in skin color associated with ethnic skin diversity. Ethnic differences exist regarding melanosome loss in keratinocytes, but the mechanisms underlying these differences, and their contribution to the regulation of skin color, remain unclear. Here, we explored the involvement of autophagy in determining skin color by regulating melanosome degradation in keratinocytes. Keratinocytes derived from Caucasian skin exhibit higher autophagic activity than those derived from African American (AA) skin. Furthermore, along with the higher autophagy activity in Caucasian skin-derived keratinocytes compared with AA skin-derived keratinocytes, Caucasian skin-derived keratinocytes were more sensitive to melanosome treatment as shown by their enhanced autophagic activity, which may reflect the substantial mechanisms in the human epidermis owing to the limitations of the models. Melanosome accumulation in keratinocytes was accelerated by treatment with lysosomal inhibitors or with small interfering RNAs specific for autophagy-related proteins, which are essential for autophagy. Furthermore, consistent with the alterations in skin appearance, the melanin levels in human skin cultured ex vivo and in human skin substitutes in vitro were substantially diminished by activators of autophagy and enhanced by the inhibitors. Taken together, our data reveal that autophagy has a pivotal role in skin color determination by regulating melanosome degradation in keratinocytes, and thereby contributes to the ethnic diversity of skin color.

Rhinovirus load and disease severity in children with lower respiratory tract infections.

It has not been clarified if there is a correlation between rhinovirus (RV) load and disease severity in the lower respiratory tract infections of hospitalized children. This study was undertaken to elucidate the contribution of the viral load to the development of disease severity in 412 children ≤3 years of age who were hospitalized with lower respiratory tract infections. The RV load in nasopharyngeal aspirates obtained from the patients at the time of admission was measured by real-time quantitative reverse-transcription polymerase chain reaction (PCR), and the clinical symptoms of the patients were assessed using a severity scoring system. Of the 412 patients, 43 (10.4%) were diagnosed with RV infections only, and 15 were determined to have high severity scores. When all patients infected with RV were assessed, there was no correlation between the viral load and the disease severity. However, there was a significant negative correlation between the disease severity and age among children <11 months of age (n = 15, ρ = -0.677, P = 0.006) and a significant positive correlation between the viral load and the disease severity among children ≥11 months of age (n = 28, ρ = 0.407, P = 0.032). Among the patients infected with RV <11 months of age, the disease severity may be associated with an immature immune response and the small diameter of their airways rather than viral load. By contrast, in the patients ≥11 months of age, viral load may contribute to the development of disease severity.

Involvement of 14-3-3 proteins in the second epidermal growth factor-induced wave of Rac1 activation in the process of cell migration.

Immense previous efforts have elucidated the core machinery in cell migration, actin remodeling regulated by Rho family small GTPases including RhoA, Cdc42, and Rac1; however, the spatiotemporal regulation of these molecules remains largely unknown. Here, we report that EGF induces biphasic Rac1 activation in the process of cell migration, and UTKO1, a cell migration inhibitor, inhibits the second EGF-induced wave of Rac1 activation but not the first wave. To address the regulation mechanism and role of the second wave of Rac1 activation, we identified 14-3-3ζ as a target protein of UTKO1 and also showed that UTKO1 abrogated the binding of 14-3-3ζ to Tiam1 that was responsible for the second wave of Rac1 activation, suggesting that the interaction of 14-3-3ζ with Tiam1 is involved in this event. To our knowledge, this is the first report to use a chemical genetic approach to demonstrate the mechanism of temporal activation of Rac1.

Determination of the temperature of bremsstrahlung photon generated by ultraintense laser using various thickness attenuators.

We evaluate the simplified method using the Lambert-Beer law to measure the temperature of bremsstrahlung photon generated by an ultraintense laser. Analytical values are compared to the results of the Monte Carlo calculation of GEANT4 and they agreed very well on the condition of the appropriate distance between the attenuator and the detector. We performed the experiment to measure the temperature of bremsstrahlung x-ray emitted from a metal target irradiated by a Ti:sapphire laser with 76 mJ, 72 fs, 2.2 × 10(18) W∕cm(2). For a Cu target of 30 µm thick, the photon temperature was reasonably determined to be 0.18 MeV, which is in good agreement with previous studies.

Tonsillectomy with methylprednisolone pulse therapy as rescue treatment for steroid-resistant IgA nephropathy in children.

Primary immunoglobulin A (IgA) nephropathy is characterized by microhematuria and proteinuria and by the deposition of IgA in the glomerular mesangium. Steroid was a main drug for treatment of IgA nephropathy. However, some of children with IgA nephropathy are resistance to steroid treatment, but the therapy for steroid-resistant IgA nephropathy was not established. There have been reports on the efficacy of tonsillectomy as an initial treatment for IgA nephropathy in adults and children. We examined whether tonsillectomy with methylprednisolone pulse therapy (tonsillectomy pulse therapy) was effective as rescue treatment for steroid-resistant pediatric IgA nephropathy. We studied 11 patients (age at onset and duration of follow-up, 11.7 +/- 2.0 and 6.2 +/- 1.1 years) who had been diagnosed with steroid-resistant IgA nephropathy. Clinical features, laboratory data, and pathological findings were retrospectively compared between before and after tonsillectomy pulse therapy. Urinary protein excretion was significantly decreased at 24.7 +/- 7.3 months after tonsillectomy pulse therapy. On renal pathologic examination of 6 patients who underwent renal biopsy at 17.1 +/- 6.9 months after tonsillectomy pulse therapy, the activity index, an index of inflammation, was lower compared to the index evaluated before the therapy, but the chronic index, an index of renal sclerosis, remained unchanged. At 24.7 +/- 7.3 months after tonsillectomy pulse therapy, seven patients had normal urine and four had minor urinary abnormalities; namely, none had active renal disease or renal insufficiency. Our findings suggest that tonsillectomy pulse therapy may be effective as rescue treatment for steroid-resistant IgA nephropathy in childhood.

IgA nephropathy in a patient with dominant dystrophic epidermolysis bullosa.

Dystrophic epidermolysis bullosa (DEB) is a rare and severe hereditary dermatosis. On the other hand, IgA nephropathy is the most common form of glomerulonephritis in childhood and adults, and clinically characterized by microhematuria and proteinuria and histologically by deposition of immunoglobulin A in mesangial lesions. Several renal complications of recessive DEB including IgA nephropathy and amyloidosis have been reported. However, there have been no reports on dominant DEB associated with IgA nephropathy. We report here for the first time a 17-year-old girl with dominant DEB associated with IgA nephropathy. The patient has suffered from episodes of urinary, upper airway, and skin infections. At 17 years of age, proteinuria and hematuria were detected, with a high value of serum IgA. Renal biopsy was performed, and immunofluorescence microscopic examination revealed segmental deposits of IgA in mesangial lesions, with many glomeruli exhibiting diffuse segmental mesangial-proliferative glomerulonephritis. We diagnosed dominant DEB associated with IgA nephropathy on the basis of proteinuria, hematuria, and deposits of IgA in mesangial lesions on immunofluorescence microscopic examination, and diffuse segmental mesangial-proliferative glomerulonephritis. These findings suggest that repeated skin infections might have contributed to the pathogenesis of IgA nephropathy in this patient.

Renal expression of alpha-smooth muscle actin and c-Met in children with Henoch-Schönlein purpura nephritis.

Alpha-smooth muscle actin (alpha-SMA) is the actin isoform that predominates within vascular smooth-muscle cells and plays an important role in fibrogenesis. On the other hand, c-Met is the receptor for hepatocyte growth factor (HGF), which plays a role in protection from injury and has anti-fibrogenetic effects. To clarify whether alpha-SMA and HGF are associated with the progression of renal injury in Henoch-Schönlein purpura nephritis (HSPN), we evaluated the renal expression of alpha-SMA and c-Met in HSPN patients. Patients were divided into three groups. Group 1 consisted of eight patients (male:female 4:4) with stage II or less in the classification of the International Study of Kidney Disease in Children (ISKDC), Group 2 consisted of 20 patients (male:female 11:9) with ISKDC stage III or greater and a good prognosis, and group 3 consisted of seven patients (male:female 3:4) with ISKDC stage III or greater and poor prognosis. Renal biopsy findings, including c-Met and alpha-SMA staining, were investigated for each group. At first biopsy, the mean scores for renal alpha-SMA and glomerular c-Met in groups 2 and 3 were higher than those in group 1, while mean scores for neither renal alpha-SMA nor glomerular c-Met differed between groups 2 and 3. At second biopsy, the mean scores for renal alpha-SMA staining in group 3 were higher than those in group 2, and mean score for glomerular c-Met staining in group 3 was lower than that in group 2. In groups 2 and 3, the mean scores for glomerular and interstitial alpha-SMA staining at first biopsy were correlated with the chronicity index (CI) at second biopsy, but the mean score for glomerular c-Met staining at first biopsy correlated with neither the activity index (AI) nor CI in the first or second biopsies in all groups. Our findings suggest that the expression of renal alpha-SMA may be associated with progression of renal injury in HSPN.

Development of glomerular endothelial cells, podocytes and mesangial cells in the human fetus and infant.

The process of glomerular development consists of four developmental stages: vesicle (V) stage, S-shaped body (S) stage, capillary loop (C) stage and maturation (M) stage. However, the development of glomerular endothelial, mesangial and epithelial cells in fetal and infant kidneys remains unclear. In order to determine the characteristics of human glomerular development, we investigated the process of glomerular development by staining fetal and infant kidneys for CD31, CD34 and FB21, markers for endothelial cells, alpha-smooth muscle actin (alpha-SMA), a marker for mesangial cells, and nephrin, a marker for podocytes. These series of studies were carried out on kidneys obtained at autopsy from 27 fetuses and 5 infants. The fetuses were divided into the following 5 groups according to gestational age; 13-19, 20-24, 25-29, 30-34 and 35-39 weeks. In each group, glomerular development was classified according to the developmental stage and the staining patterns for CD31, CD34, FB21, alpha-SMA and nephrin. The proportion of V-stage development in 100 glomeruli examined was highest at 13-19 weeks. After 20 weeks, the V-stage proportion decreased gradually, and the proportion of S stage became highest at 20-24 weeks. The C-stage proportion was highest at 25-29 weeks, while the M-stage proportion was highest in infants aged 1-6 months. The staining patterns for CD31, CD34 and FB21 were similar in endothelial cells after 25 weeks of gestation. Staining of alpha-SMA and nephrin was first observed in the S stage. In conclusion, maturation of endothelial cells starts at 25 weeks and is completed by 35 weeks of gestation. Epithelial cells and mesangial cells first appear during the S stage.

Efficacy of steroid pulse, plasmapheresis, and mizoribine in a patient with focal segmental glomerulosclerosis.

There have been few reports on successful treatment for focal segmental glomerulosclerosis (FSGS) complicated by leukoencephalopathy. We report the efficacy of the steroid pulse and mizoribine (MZB) combined with plasmapheresis (PP) for a case of FSGS with leukoencephalopathy induced by cyclosporine (CyA). The patient was a 4-year-old boy with FSGS who presented with steroid-resistant nephrotic syndrome (NS) and was treated with CyA. On the 7th day after starting CyA, he complained of one visual disorder, and hypertension and tonic convulsions were observed. Electroencephalography (EEG) revealed generalized slow waves, and magnetic resonance imaging (MRI) disclosed high signal intensity in the white matter. A diagnosis of leukoencephalopathy induced by CyA was made on the basis of these findings with the improvement in clinical manifestations upon discontinuation of CyA. We treated the patient with steroid pulse therapy and MZB combined with PP, and the proteinuria gradually decreased and only microscopic hematuria remained. We report that steroid pulse and MZB combined with PP may be an effective treatment in a patient with FSGS complicated by CyA-induced leukoencephalopathy.

Efficacy of single dose of oral mizoribine pulse therapy two times per week for frequently relapsing nephrotic syndrome.

We assessed the efficacy of a single dose of oral mizoribine (MZB) pulse therapy two times per week for children with frequently relapsing nephrotic syndrome (FRNS). Eleven children with FRNS in remission were treated with oral MZB pulse therapy (daily dose 6 mg/kg; maximum total dose 300 mg). We compared their clinical manifestations before and after oral MZB pulse therapy and examined the changes in serum MZB concentration in each patient on the days when MZB was administered. Eight patients had no subsequent relapses (responders), and prednisolone could be discontinued. Although 2 of the other 3 patients (nonresponders) had one relapse and the remaining patient had two relapses, both the dosages of prednisolone and frequency of relapse after oral MZB pulse therapy were significantly lower than before oral MZB pulse therapy. The peak blood concentration and AUC0-4 of MZB in the responders were higher than in the nonresponders. None of patients had severe adverse effects, such as uricacidemia, leukopenia, liver dysfunction or alopecia. Oral mizoribine pulse therapy consisting of a single dose two days a week may be effective and safe in some FRNS patients.