Synthesis of Topological Gels by Penetrating Polymerization Using a Molecular Net.

Topological gels possess structures that are cross-linked only via physical constraints; ideally, no attractive intermolecular interactions act between their components, which yields interesting physical properties. However, most reported previous topological gels were synthesized based on supramolecular interlocked structures such as polyrotaxane, for which attractive intermolecular interactions are essential. Here, we synthesize a water-soluble "molecular net" (MN) with a large molecular weight and three-dimensional network structure using poly(ethylene glycol). When a water-soluble monomer (N-isopropylacrylamide) is polymerized in the presence of the MNs, the extending polymer chains penetrates the MNs to form an ideal topological MN gel with no specific attractive interactions between its components. The MN gels show unique physical properties as well a significantly high degree of swelling and high extensibility due to slipping of the physical cross-linking. We postulate this method to yield a new paradigm in gel science with unprecedented physical properties.

Three-dimensional spheroid culture induces apical-basal polarity and the original characteristics of immortalized human renal proximal tubule epithelial cells.

The proximal tubules, which are part of the kidney, maintain blood homeostasis by absorbing amino acids, glucose, water, and ions such as sodium (Na), potassium, and bicarbonate. Proximal tubule dysfunction is associated with the pathogenesis of many kidney diseases. Renal proximal tubular epithelial cells (RPTECs) are responsible for the main functions of the proximal tubules. Therefore, in vitro experiments using RPTECs would greatly enhance our understanding of nephron physiology and pathobiology. It is preferable to use immortalized cell lines, such as human kidney-2 (HK-2) cells, because they are derived from humans and maintain growth indefinitely. However, tissue-specific RPTEC phenotypes, including apical-basal polarization, are frequently lost in conventional two-dimensional culture methods in part due to microenvironmental deficiencies. To overcome this limitation, we developed a three-dimensional (3D) spheroid culture method for HK-2 cells using an extracellular matrix. HK-2 spheroids in 3D culture formed a tubule-like architecture with cellular polarity and showed markedly restored Na transport function. 3D culture of HK-2 cells also increased expression of kidney development-related genes, including WNT9B. Models of human renal tubules using HK-2 spheroids will greatly improve our understanding of the physiology and pathobiology of the kidney.

Severe refractory TAFRO syndrome requiring continuous renal replacement therapy complicated with Trichosporon asahii infection in the lungs and myocardial infarction: an autopsy case report and literature review.

BACKGROUND: TAFRO (thrombocytopenia, anasarca, fever, reticulin myelofibrosis/renal failure, and organomegaly) syndrome is a systemic inflammatory disorder and unique clinicopathological variant of idiopathic multicentric Castleman disease that was proposed in Japan. Prompt diagnosis is critical because TAFRO syndrome is a progressive and life threating disease. Some cases are refractory to immunosuppressive treatments. Renal impairment is frequently observed in patients with TAFRO syndrome, and some severe cases require hemodialysis. Histological evaluation is important to understand the pathophysiology of TAFRO syndrome. However, systemic histopathological evaluation through autopsy in TAFRO syndrome has been rarely reported previously. CASE PRESENTATION: A 46-year-old Japanese man with chief complaints of fever and abdominal distension was diagnosed with TAFRO syndrome through imaging studies, laboratory findings, and pathological findings on cervical lymph node and bone marrow biopsies. Interleukin (IL)-6 and vascular endothelial growth factor (VEGF) levels were remarkably elevated in both blood and ascites. Methylprednisolone (mPSL) pulse therapy was initiated on day 10, followed by combination therapy with PSL and cyclosporine A. However, the amount of ascites did not respond to the treatment. The patient became anuric, and continuous renal replacement therapy was initiated from day 50. However, the patient suddenly experienced cardiac arrest associated with myocardial infarction (MI) on the same day. Although the emergent percutaneous coronary intervention was successfully performed, the patient died on day 52, despite intensive care. Autopsy was performed to ascertain the cause of MI and to identify the histopathological characteristics of TAFRO syndrome. CONCLUSIONS: Bacterial peritonitis, systemic cytomegalovirus infection, and Trichosporon asahii infection in the lungs were observed on autopsy. In addition, sepsis-related myocardial calcification was suspected. Management of infectious diseases is critical to reduce mortality in patients with TAFRO syndrome. Although the exact cause of MI could not be identified on autopsy, we considered embolization by fungal hyphae as a possible cause. Endothelial injury possibly caused by excessive secretion of IL-6 and VEGF contributed to renal impairment. Fibrotic changes in anterior mediastinal fat tissue could be a characteristic pathological finding in patients with TAFRO syndrome.

Peritoneal dialysis-associated catheter infection caused by Mycobacterium abscessus in an elderly patient who was successfully treated with catheter removal.

An 89-year-old Japanese man on peritoneal dialysis (PD) was suspected of having a PD-associated catheter infection. He visited the hospital because of the discharge of pus from the exit site of his catheter. Gram staining of the pus showed Gram-positive bacilli, but these were acid-fast bacilli. The rapidly growing nontuberculous mycobacteria, Mycobacterium abscessus, was isolated. PD catheter removal and debridement were immediately performed. The patient received combination antibiotic therapy. His clinical course was good, but he required hemodialysis due to the discontinuation of PD. However, the patient and his family chose not to continue hemodialysis even when the symptoms of uremia appeared. Best supportive care was arranged by his primary care physician. M. abscessus is a rare causative organism for PD-associated catheter infections and is difficult to treat. In our case, a rapid and precise diagnosis was made using acid-fast staining and Mycobacterium culture. The risk of nontuberculous mycobacterial infections should be considered in patients on PD.

Skin Perfusion Pressure and the Prevalence of Atherothrombosis in Hemodialysis Patients.

End-stage renal disease is associated with atherothrombosis (ATIS), which, in turn, can promote peripheral arterial occlusive disease (PAOD), coronary artery disease (CAD), and/or cerebrovascular disease (CVD). The aim of this study was to determine whether low plantar skin perfusion pressure (SPP) was related to ATIS among 122 patients receiving maintenance hemodialysis (HD) from March to November 2013 at our outpatient facility. We routinely measured SPP and used the value for analysis. In addition, we retrospectively evaluated the prevalence of ATIS with patients categorized to CAD, CVD, or PAOD groups. Of the 122 outpatients, ATIS was diagnosed in about half (N = 60, 49.2% vs. 62, 50.8%; average SPP, 56.6 vs. 72.9 mm Hg, respectively). These data show that SPP was significantly lower in patients with ATIS (difference, 16.3 mm Hg; P < 0.001) and there was a negative relationship between average SPPs and past history of ATIS complications. When the patients were stratified by the presence of diabetes mellitus, this trend was stronger. Particularly, receiver operating characteristic analysis of HD patients with diabetes revealed a cutoff point of 53.0 mm Hg and an area under the curve value of 0.84, with a sensitivity of 77.0% and specificity of 91.3%. Therefore, we concluded that SPP enables the evaluation of not only local PAOD, but also systemic ATIS. Moreover, we found that a cutoff point of 53.0 mm Hg was useful for detection of ATIS in HD patients.