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A 57-year-old Japanese man on peritoneal dialysis developed peritoneal dialysis-associated peritonitis caused by Rhodococcus corynebacterioides. After the introduction of peritoneal dialysis, he had experienced four episodes of peritonitis, but the causative organism was not identified in any of episode. When he was hospitalized for the fifth episode of peritonitis, Rhodococcus corynebacterioides was detected in the ascitic fluid. He improved after an intraperitoneal administration of vancomycin (VCM) that was used based on the treatment of peritonitis caused by Corynebacterium spp. However, he then had repeated flare-ups and eventually required the removal of the peritoneal dialysis catheter due to recurrent peritonitis. 16S rRNA gene sequencing is generally needed to positively identify Rhodococcus corynebacterioides. In this case, we were able to rapidly identify the organism by using mass spectrometry and then apply this knowledge to the patient's treatment. To the best of our knowledge, this is the first reported case of peritoneal dialysis-associated peritonitis caused by Rhodococcus corynebacterioides.

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Erdheim-Chester disease, a rare non-Langerhans histiocytosis, involves multiple organs, including kidney. Renal dysfunction sometimes occurs, and is attributed to ureteral obstruction and renal artery stenosis by histiocytic infiltration. However, to our knowledge, case reports of end-stage renal disease requiring renal replacement therapy due to Erdheim-Chester disease are very few. Here, we report a 69-year-old woman who was diagnosed with Erdheim-Chester disease 10 years ago. She had multiple organ involvement, such as bone, skin, heart, pituitary gland, kidney, and retroperitoneum. She had been treated with interferon-alpha, but discontinued after 2 years due to depression and repeated infection. She did not desire treatment with other drugs, so we continued supportive care. Her renal function gradually deteriorated, and hemodialysis was initiated 4 years ago. Subsequently, she is still doing well without any major symptoms. This report describes an unusual case of Erdheim-Chester disease requiring maintenance hemodialysis that longer prognosis than expected was obtained regardless of multiple organ involvement and no specific treatment after interferon-alpha cessation.

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Although bisphosphonates are well known to cause kidney disease, there are very few published cases of focal segmental glomerulosclerosis (FSGS) following treatment with minodronate. Here we report the case of an 86-year-old woman who developed acute kidney injury and nephrotic syndrome after receiving monthly oral minodronate for 24 months. Kidney biopsy revealed cellular variant FSGS. Treatment was initiated with the discontinuation of minodronate followed by intravenous methylprednisolone pulse and prednisolone at 35 mg/day. Subsequently, the patient's renal function gradually worsened, requiring initiation of hemodialysis. However, renal function and proteinuria improved markedly and hemodialysis was withdrawn 1 month after the initiation of steroid therapy. This is, to our knowledge, the first published case of FSGS induced by long-term use of minodronate, and also the first case of cellular variant FSGS induced by bisphosphonates although collapsing variant of FSGS is commonly caused by bisphosphonates. Our study indicates that patients on bisphosphonates should be closely monitored for proteinuria and renal impairment, regardless of the type of bisphosphonate.

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An 81-year-old female patient underwent an emergent surgery because of small intestinal perforation. Within a 5-mm-sized hole in ileum, a half-folded, empty polyethylene drug-wrapping film with the drug names, date, and her name was found.

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Optimal ferritin level in hemodialysis patients between Japan and other countries is controversial. Long-term side effects of iron supplementation in these patients remain unclear. We aimed to elucidate whether past hyperferritinemia in hemodialysis patients was associated with high risk of death and cerebrovascular and cardiovascular diseases (CCVDs). This small retrospective cohort study included approximately 44 patients unintentionally supplemented with excessive intravenous iron. A significantly higher risk of CCVDs was observed in patients with initial serum ferritin levels ≥1000 ng/mL than in the remaining patients. High ferritin levels slowly decreased to <300 ng/mL in a median of 24.2 (10.5-46.5) months without treatment. However, compared with the remaining patients, only patients whose ferritin levels did not decrease to <300 ng/mL steadily had a significantly higher risk of all-cause death (hazard ratio, 9.6). Long-term hyperferritinemia due to intravenous iron therapy is a risk factor for death in maintenance hemodialysis patients. For a prolonged better prognosis, intravenous iron should be carefully administered so as to avoid hyperferritinemia in patients with hemodialysis.

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IgG4-related disease (IgG4RD) is a multi-organ disorder characterized by an elevated serum IgG4 level and IgG4-positive plasma cell infiltration of the affected organs, accompanied by tissue fibrosis and sclerosis. Although it can affect any organ, to our knowledge, no cases involving concurrent autoimmune neutropenia and thrombocytopenia have been reported. A 62-year-old man visited our hospital and was diagnosed with IgG4RD accompanied by interstitial pneumonitis, lymphadenopathy, and interstitial nephritis. During his clinical course, he developed autoimmune neutropenia and idiopathic thrombocytopenic purpura. Our case, invoving multiple hematological abnormalities, might help deepen our understanding of the pathophysiology of IgG4RD.

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Immunoglobulin G4-related disease is a rare immune-mediated disease characterized by the infiltration of IgG4-positive plasma cells and unique storiform fibrosis of multiple organs. The majority of IgG4-related disease patients respond to glucocorticoids, yet the precise mechanism of their action remains unclear. Pathological sections of the submaxillary gland, kidney, and retroperitoneum from 20 patients in total diagnosed with IgG4-related disease were analyzed for glucocorticoid receptor expression and the cell types expressing glucocorticoid receptor. Strong and abundant expression of glucocorticoid receptor was observed in the submaxillary gland, kidney, and retroperitoneum of IgG4-related disease patients, while glucocorticoid receptor was rarely or only faintly observed in the submaxillary gland of patients with Sjögren's syndrome, radicular cysts and sialolithiasis or in the healthy kidney. Glucocorticoid receptor was mainly expressed in fibro/myofibroblasts, CD4-positive T cells and IgG4-positive plasma cells in the submandibular glands and kidneys of IgG4-related disease patients. The abundant expression of glucocorticoid receptor in various types of cells, including resident fibro/myofibroblasts in IgG4-related disease patients might provide clues to the mechanism of steroid responsiveness in IgG4-related disease patients.

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Acute renal failure with severe loin pain and patchy renal ischemia after anaerobic exercise (ALPE) is exercise-induced acute renal failure that occurs without myoglobinuria. We describe a typical case involving an 18-year-old man. Generally, patients with ALPE are advised to avoid anaerobic exercise due to risk of recurrence, but our patient continued and went on to become a professional cyclist without relapse. About 51% of ALPE cases involve patients with renal hypouricemia. His serum uric acid levels were rather high, at 6.4 mg/dL. He is the first patient with ALPE to succeed as a professional athlete in an anaerobic sport.

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Acute kidney injury (AKI) is an increasingly common clinical problem with significant impact on long-term patient outcome. Recent clinical trials demonstrate that AKI is closely related to the progression of chronic kidney disease (CKD) and end-stage renal disease, though the precise mechanisms linking AKI to CKD remain unclear. While inflammation, microvascular rarefaction and hypoxia are involved in the AKI-to-CKD continuum, proximal tubule injury seems to play an important role in the progression of CKD. In this review, we focus on the mechanisms of the AKI-to-CKD continuum, especially the mechanism by which injury to the proximal tubules triggers progression to CKD. Elucidating the mechanisms involved in the AKI-to-CKD continuum will support the development of therapeutic options to prevent progression from AKI to CKD. © 2016 S. Karger AG, Basel.

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AKI increases the risk of developing CKD, but the mechanisms linking AKI to CKD remain unclear. Because proximal tubule injury is the mainstay of AKI, we postulated that proximal tubule injury triggers features of CKD. We generated a novel mouse model to induce proximal tubule-specific adjustable injury by inducing the expression of diphtheria toxin (DT) receptor with variable prevalence in proximal tubules. Administration of high-dose DT in mice expressing the DT receptor consistently caused severe proximal tubule-specific injury associated with interstitial fibrosis and reduction of erythropoietin production. Mild proximal tubule injury from a single injection of low-dose DT triggered reversible fibrosis, whereas repeated mild injuries caused sustained interstitial fibrosis, inflammation, glomerulosclerosis, and atubular glomeruli. DT-induced proximal tubule-specific injury also triggered distal tubule injury. Furthermore, injured tubular cells cocultured with fibroblasts stimulated induction of extracellular matrix and inflammatory genes. These results support the existence of proximal-distal tubule crosstalk and crosstalk between tubular cells and fibroblasts. Overall, our data provide evidence that proximal tubule injury triggers several features of CKD and that the severity and frequency of proximal tubule injury determines the progression to CKD.

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BACKGROUND: Acute kidney injury (AKI) is a common complication accompanying cardiopulmonary bypass (CPB) and is independently associated with increased morbidity and death. Diabetes mellitus increases the risk for AKI after CPB. Epigallocatechin-3-gallate (EGCG) is a major component of the polyphenolic fraction of green tea, which possesses cardioprotective activities, as previously reported. We hypothesized that EGCG also possesses a renoprotective effect through its diverse biochemical properties and assessed the effect on renal function after CPB for diabetic rats. METHODS: Goto-Kakizaki rats developing type 2 diabetes mellitus were randomly assigned to one of the following groups: sham (n = 10), CPB (CPB alone, n = 9), or EGCG (CPB + EGCG, n = 10). CPB was conducted for 30 minutes at a flow rate of 100 mL/kg/min in the CPB and EGCG groups. Rats assigned to the EGCG group were administrated EGCG solution orally for 2 weeks before CPB. We evaluated renal biochemical or histologic changes at 24 hours after CPB. RESULTS: Compared with the CPB group, the EGCG group exhibited milder tubular injury histologically (p < 0.0001) and reduced expression of kidney injury molecule-1, a biomarker for renal tubular injury (p < 0.0001) and 8-hydroxy-2'-deoxyguanosine (p < 0.01), indicating attenuated oxidant stress. CONCLUSIONS: Preoperative oral administration of EGCG ameliorates AKI in a CPB model of diabetic rats through antioxidative properties. This simple method could be applied in a clinical setting as a prophylactic renal protection against AKI after CPB, especially for high-risk patients with diabetes mellitus.

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Epidemiological findings indicate that acute kidney injury (AKI) increases the risk for chronic kidney disease (CKD), although the molecular mechanism remains unclear. Genetic fate mapping demonstrated that nephrons, functional units in the kidney, are repaired by surviving nephrons after AKI. However, the cell population that repairs damaged nephrons and their repair capacity limitations remain controversial. To answer these questions, we generated a new transgenic mouse strain in which mature proximal tubules, the segment predominantly damaged during AKI, could be genetically labelled at desired time points. Using this strain, massive proliferation of mature proximal tubules is observed during repair, with no dilution of the genetic label after the repair process, demonstrating that proximal tubules are repaired mainly by their own proliferation. Furthermore, acute tubular injury caused significant shortening of proximal tubules associated with interstitial fibrosis, suggesting that proximal tubules have a limited capacity to repair. Understanding the mechanism of this limitation might clarify the mechanism of the AKI-to-CKD continuum.

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The kidney has the capacity to recover from ischemic and toxic insults. Although there has been debate about the origin of cells that replace injured epithelial cells, it is now widely recognized that intrinsic surviving tubular cells are responsible for the repair. On the other hand, the cells, which have stem cell-like characteristics, have been isolated in the kidney using various methods, but it remains unknown if these stem cells actually exist in the adult kidney and if they are involved in kidney regeneration. This review will focus on the pathophysiology of kidney regeneration and the contribution of renal stem cells. We also discuss possible therapeutic applications to kidney disease.

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BACKGROUND: Secondary hyperparathyroidism is one of the critical complications of end-stage renal disease patients. Conventionally intact parathyroid hormone (iPTH) was used to assess secondary hyperparathyroidism, but this assay measures both PTH(1-84) (full-length parathyroid hormone) and PTH(7-84) (amino (N)-terminal-cleaved parathyroid hormone). PTH(7-84) is biologically inactive or antagonistic for PTH. In this study, we examined the relationship between serum calcium concentration and PTH(7-84)/PTH(1-84) ratio and the effect of calcimimetics on the ratio in hemodialysis (HD) patients. METHODS: Ionized-calcium (iCa), iPTH, and whole PTH (wPTH) were measured at the start of HD sessions on HD patients. Patients were divided into four groups by presence (+) or absence (-) of vitamin D (VD) and calcimimetics (CM). RESULT: PTH(7-84)/PTH(1-84) ratios of the four groups [VD(-)CM(-), VD(+)CM(-), VD(-)CM(+) and VD(+)CM(+)] were 0.735, 0.799, 0.844, and 1.156, respectively. In VD(-)CM(-) and VD(+)CM(-) groups, iCa and PTH(7-84)/PTH(1-84) ratio showed equilateral correlation (r = 0.634, p < 0.001 and r = 0.360, p < 0.01, respectively). In calcimimetics-treated group, iCa and PTH(7-84)/PTH(1-84) ratio did not show correlation. CONCLUSION: Whereas in the absence of calcimimetics cleavage of N-terminal PTH was regulated by serum calcium concentration, this regulation was abolished in the presence of calcimimetics. This suggests that cleavage of N-terminal PTH is regulated by calcium concentration via a calcium-sensing receptor and that calcimimetics may have a novel effect to reduce PTH level.

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