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Introduction: Peritonitis is a significant complication of peritoneal dialysis (PD). Additionally, in severe or prolonged cases of peritonitis, the structure and function of the peritoneum may change, making it difficult to continue PD. Thus, identifying the causative agent and early administration of antibiotics are essential to minimize the risk of treatment failure. Meanwhile, bacterial peritonitis caused by nontuberculous Mycobacteria (NTM) are difficult to identify. NTM are also among the most difficult organisms to eradicate. Oftentimes, removal of the peritoneal catheter and multiple antibiotics are required to eradicate NTM infections., Case Presentation: Herein, we report a case of peritonitis caused by Mycobacterium fortuitum in a 3-year-old boy undergoing PD. The patient had a history of an initial PD catheter exit site infection caused by M. fortuitum that led to PD-associated peritonitis. Consequently, the catheter was removed, and the patient was switched to hemodialysis and treated with multiple antibiotics., Conclusion: This rare cause of peritonitis is associated with a high mortality and severe morbidity and usually requires removal of the PD catheter as well as prolonged treatment with multiple antibiotics. When there is NTM infection around the PD catheter, such as in an ulcer, it is necessary to remove the catheter and transition to a hemodialysis until the infection has healed., Competing Interests: All authors declare that this manuscript has no conflict of interest., (© 2024 The Author(s). Published by S. Karger AG, Basel.)

Key Clinical Message: Pseudohypoaldosteronism (PHA) carries a good prognosis if treated early and appropriately, but some cases can have life-threatening events. We underscored the need to consider secondary PHA as one of the differential diagnoses of hyponatremia and hyperkalemia in infancy., Abstract: Pseudohypoaldosteronism (PHA) type 1 has two classifications; the primary type, caused by genetic abnormalities that develop during neonatal and infancy periods, and the secondary type, caused by urinary tract malformation and urinary tract infection. Secondary PHA, if treated early and appropriately, has a good prognosis; however, some cases can present life-threatening events. Therefore, early diagnosis is crucial. We present a case of early infancy secondary PHA presented with marked hyponatremia and poor weight gain. The patient's growth and development improved with secondary PHA treatment. Here, were demonstrated the value of prompt action against infection and electrolyte imbalance and the importance of imaging for diagnosis, and underscore the need to consider secondary PHA as a differential diagnoses of hyponatremia and hyperkalemia in infancy. However further studies, including basic research, to elucidate the diseases pathology is warranted., Competing Interests: The authors have no conflict of interest to declare., (© 2024 The Authors. Clinical Case Reports published by John Wiley & Sons Ltd.)

Congenital nephrogenic diabetes insipidus (CNDI), a rare hereditary disorder, is characterized by the inability of the kidneys to concentrate urine in response to the antidiuretic hormone arginine vasopressin (AVP); as a result, large volumes of unconcentrated urine are excreted. In addition to the clinical manifestations of CNDI, such as dehydration and electrolyte disturbances (hypernatremia and hyperchloremia), developmental delay can result without prompt treatment. In approximately 90% of cases, CNDI is an X-linked disease caused by mutations in the arginine vasopressin receptor 2 ( AVPR2 ) gene. In approximately 9% of cases, CNDI is an autosomal recessive disease caused by mutations in the water channel protein aquaporin 2 ( AQP2 ), and 1% of cases are autosomal dominant. We report a case of CNDI caused by a novel AVPR2 nonsense mutation, c.520C>T (p.Q174X), and cases of siblings in another family who had a different AVPR2 nonsense mutation, c.852G>A (p.W284X). Both cases responded well to treatment with hydrochlorothiazide and spironolactone. If CNDI is suspected, especially in carriers and neonates, aggressive genetic testing and early treatment may alleviate growth disorders and prevent irreversible central nervous system disorders and developmental delay., Competing Interests: All authors declare that this manuscript has no conflict of interest., (© 2023 The Author(s). Published by S. Karger AG, Basel.)

Key Clinical Message: Although percutaneous renal biopsy is considered safe, this invasive procedure has complications such as renal arteriovenous fistula (RAVF). Even if complications such as RAVFs are not observed early after renal biopsy, considering the possibility of delayed renal hemorrhage, follow-up with ultrasound after renal biopsy even in asymptomatic cases could be important., Abstract: Although percutaneous renal biopsy is considered safe, this invasive procedure can lead to complications such as renal arteriovenous fistula (RAVF). RAVF occurs when some arteries and veins communicate in the absence of capillaries in the renal hilum or renal parenchyma. It was previously thought to be relatively rare; however, with advances in imaging diagnostics, it is sometimes found asymptomatically. In addition, renal biopsy is the most common cause of acquired RAVF. In this case, RAVF was discovered 2 years after renal biopsy. Late-onset RAVF is scarce. This case highlights that even if complications such as RAVFs are not observed early after renal biopsy, considering the possibility of delayed RAVF, follow-up with ultrasound could be important., Competing Interests: None declared., (© 2023 The Authors. Clinical Case Reports published by John Wiley & Sons Ltd.)

Potter syndrome, first reported in 1946 by Edith Potter, refers to fatal cases of bilateral renal aplasia with pulmonary hypoplasia, peculiar facial features, and limb deformities. Presently, patients with oligohydramnios showing similar pathological manifestations due to oligohydramnios caused by conditions other than bilateral renal aplasia have been reported, and are known as the Potter sequence. There are limited studies and unclear guidelines on the safest delivery time and detailed postpartum management for patients with the Potter sequence. We experienced a case of Potter sequence, in which the patient was born by elective cesarean section at gestational age (GA) of 34 weeks. Fetal ultrasound at GA of 26 weeks 4 days showed oligohydramnios, multilocular cystic lesions in the left kidney, and an absent right kidney. Prenatal fetal MRI at GA of 33 weeks and 3 days showed pulmonary hypoplasia, and the ratio of fetal lung volume (FLV) to fetal body weight (FBW) was 0.0135 ml/g. We suspected that the fetal lung could not grow because of persistent oligohydramnios, which leads to a further decline in the ratio of FLV to FBW during pregnancy. We performed a cesarean section at GA of 34 weeks to prevent the exacerbation of the imbalance between lung volume and physique. We struggled to keep her condition stabilized with strict management of her respiratory condition, dialysis, and nutrition. She was discharged from the hospital at 169 days of age. Elective caesarean section in the term of premature birth prevented the progression of pulmonary hypoplasia and made it possible to save her life. Potter sequence is still relatively unknown, and it is necessary for more studies to be conducted in the future., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2023 Yuya Kinoshita et al.)

Background: Membranoproliferative glomerulonephritis (MPGN), a rare glomerulonephritis that causes nephrotic syndrome in children, is often difficult to treat. Typical immunofluorescence findings include strong C3 staining in a granular pattern along the glomerular capillary wall and negative IgA staining. IgA-dominant MPGN without hypocomplementemia has been reported. Herein, we report a rare case of MPGN with hypocomplementemia and predominant IgA subclass 2 deposits., Case Presentation: An 11-year-old girl showed proteinuria on a school urinalysis screening and presented with upper eyelid edema. The urinalysis showed elevated urinary protein levels and hematuria. Laboratory examinations revealed the following: serum albumin, 1.3 g/dL; serum creatinine, 0.54 mg/dL; and C3c, 67 mg/dL (normal range: 73-138 mg/dL). The physical and laboratory findings did not suggest autoimmune diseases. A renal biopsy was then performed. Specimen examination under a light microscope showed mesangial cell proliferation, increased mesangial matrix with lobulation, and some double contours of the glomerular basement membrane in almost all glomeruli, which are characteristic findings of MPGN. Immunofluorescent studies showed IgA deposits not only in the mesangial regions but also along the capillary walls, which were more strongly stained than C3. IgA subclass staining showed a stronger immunoreactivity for IgA2 than IgA1. Electron microscopic studies showed electron-dense deposits in the subendothelial, subepithelial, and paramesangial regions. Based on these findings, the patient was diagnosed with IgA-dominant MPGN. Accordingly, she was treated with three courses of methylprednisolone pulse therapy (MPT), followed by prednisolone, mizoribine, and lisinopril. Although hypocomplementemia improved after three courses of MPT, nephrotic-range proteinuria and hypoalbuminemia remained; therefore, two courses of MPT were additionally administered, and the immunosuppressant was changed from mizoribine to cyclosporine (CsA). Finally, the urinary protein level decreased, and a subsequent renal biopsy, two years later, showed improvement in the lesions., Conclusions: We report an atypical case of MPGN with IgA2 dominant deposits along the glomerular capillary wall and in the mesangial region. The case was refractory to standard therapy but sensitive to CsA, which resulted in remission. Our findings suggest that CsA may be useful as an immunosuppressant to treat refractory MPGN., (© 2022. The Author(s).)

Immunothrombocytopenic purpura is a possible complication after liver transplant. The therapy for immunothrombocytopenic purpura after liver transplant is similar to that of primary immunothrombocytopenic purpura. This therapy consists of corticosteroids, intravenous immunoglobulin, and immunosuppressive agents such as cyclosporine and rituximab. There are a few cases of immunothrombocytopenic purpura in patients who recovered after cessation of tacrolimus administration. Here, we show an intractable case of immunothrombocytopenic purpura in a living related liver transplant recipient treated with some of these. We observed complete remission after switch ofthe immunosuppressive agent from tacrolimus to cyclosporine. The patient was an infant girl aged 18 months who underwent livingr elated liver transplant for biliary atresia when she was 6 months old. Liver graft was a left lateral segment from her father. Purpura and severe thrombocytopenia developed after 11 months.There was no effect of the first-line therapies, as described in the Japan guidelines for immunothrombocytopenic purpura.Thrombocytopenia was extreme, as shown by a blood count of 0 platelets/μL. Administration of rituximab was started. However, her platelet count had not increased 8 weeks after rituximab initiation. As a trial therapy, we switched tacrolimus to cyclosporine. She showed complete remission 1 month after this drug conversion. Thus, a switch from tacrolimus to other immunosuppressive agents as a therapy for immunothrombocytopenic purpura after living related liver transplant should be considered.

It has been postulated that measles virus infection is associated with remission of idiopathic nephrotic syndrome (INS) in childhood. There are few reports on the correlation of INS remission with other infections. Previously, there have been two case reports suggesting an association between influenza B virus infection and the remission of INS. The patient was an 18-year-old Japanese woman. The onset of steroid-sensitive NS was at 9 years of age, and pathological diagnosis was minimal change nephrotic syndrome (MCNS). Until 10 months prior to visiting our hospital, the patient's NS was in remission. The patient experienced fever, cough, and malaise and she was diagnosed with type B influenza by a local physician 4 days before visiting our hospital. The patient had vomiting and diarrhea 1 day prior to visiting our hospital. Her weight was 54.7 kg (+5.0 kg) and she had pitting edema of both lower legs. Her serum albumin level was 0.9 g/dL, proteinuria level was 8.73 g/gCr, and urine sediments showed 1-4 red blood cells per high-power field. She was diagnosed with relapse of NS. The level of proteinuria decreased to 0.03 g/gCr with rest alone on day 4 of admission, and a complete remission from NS was observed at approximately 2 weeks after the onset of influenza B infection. We report a rare case wherein spontaneous remission of NS occurred within a short period of 2 weeks after influenza B infection. It is clear that some immunity is involved in the pathogenesis of INS, but there are some cases in which infection improves NS and others in which it recurs., Competing Interests: All authors declare that they have no conflict of interest relating to this case report., (Copyright © 2021 by S. Karger AG, Basel.)

Patients with nephrogenic diabetes insipidus should establish a support network system by contacting the government to ensure that water can be preferentially obtained in the event of a disaster and create and carry a medical alert card., Competing Interests: The authors have declared that no conflict of interest exists., (© 2020 The Authors. Clinical Case Reports published by John Wiley & Sons Ltd.)

5-[4-(1-Hydroxyethyl)phenyl]-10,15,20-triphenylporphyrin (1a) and zinc porphyrin 1b were designed and synthesized to experimentally examine the validity of the transition-state model previously proposed for the lipase-catalyzed kinetic resolution of secondary alcohols. The lipases from Pseudomonas cepacia (lipase PS), Candida antarctica (CHIRAZYME L-2), Rhizomucor miehei (CHIRAZYME L-9), and Pseudomonas aeruginosa (lipase LIP) exhibited excellent enantioselectivity (E >100 at 30 degrees C). Subtilisin Carlsberg from Bacillus licheniformis (ChiroCLEC-BL) also showed high enantioselectivity for 1a (E = 140 at 30 degrees C), and the thermodynamic parameters were determined: DeltaDeltaH = -6.8 +/- 0.8 kcal mol(-1), DeltaDeltaS = -13 +/- 3 cal mol(-1) K(-1). Lipases and subtilisin showed R- and S-preference for 1, respectively. The mechanisms underlying the experimental observations are explained in terms of the transition-state models. The large secondary alcohol 1 is a powerful tool for investigating the conformation of the transition state of the enzyme-catalyzed reactions. The fact that 1 was resolved with high enantioselectivity strongly suggests that the gauche conformation, but not the anti conformation, is taken in the transition state, in agreement with the transition-state models involving the stereoelectronic effect.