Highly conductive, stretchable and biocompatible Ag-Au core-sheath nanowire composite for wearable and implantable bioelectronics.

Wearable and implantable devices require conductive, stretchable and biocompatible materials. However, obtaining composites that simultaneously fulfil these requirements is challenging due to a trade-off between conductivity and stretchability. Here, we report on Ag-Au nanocomposites composed of ultralong gold-coated silver nanowires in an elastomeric block-copolymer matrix. Owing to the high aspect ratio and percolation network of the Ag-Au nanowires, the nanocomposites exhibit an optimized conductivity of 41,850 S cm-1 (maximum of 72,600 S cm-1). Phase separation in the Ag-Au nanocomposite during the solvent-drying process generates a microstructure that yields an optimized stretchability of 266% (maximum of 840%). The thick gold sheath deposited on the silver nanowire surface prevents oxidation and silver ion leaching, making the composite biocompatible and highly conductive. Using the nanocomposite, we successfully fabricate wearable and implantable soft bioelectronic devices that can be conformally integrated with human skin and swine heart for continuous electrophysiological recording, and electrical and thermal stimulation.

A case of ANCA-associated vasculitis presenting with calf claudication.

Wegener's granulomatosis (WG), Churg-Strauss syndrome, and microscopic polyangiitis (MPA) are closely related small vessel vasculitides characterized by anti-neutrophil cytoplasmic antibodies (ANCA). Although there were some reports of MPA presenting with claudication, there are very few reports on WG presenting with claudication of calf muscles. We report an unusual case of ANCA-associated vasculitis in a 75-year-old man who presented with bilateral calf claudication. Comprehensive evaluations, including electromyography, nerve conduction study, lower extremity magnetic resonance imaging, and Doppler scan, did not reveal any other cause of bilateral calf claudication. P-ANCA and anti-myeloperoxidase antibody was positive, but the anti-proteinase 3 antibody was negative. Chest computed tomography scan showed subpleural honeycombing and reticulation, predominantly in both basal lung areas. Biopsy of the calf muscle showed granulomatous vasculitis. Kidney biopsy was also performed which revealed focal necrotizing glomerulonephritis. Our patient does not exhibit typical clinical features for WG, but histopathologic findings of necrotizing granulomatous vasculitis in calf muscle biopsy is highly suggestive of WG.

Proper management and follow-up strategy of branch duct intraductal papillary mucinous neoplasms of the pancreas.

BACKGROUND AND AIM: It has been reported that main duct intraductal papillary mucinous neoplasms are more invasive and have a worse prognosis than branch duct intraductal papillary mucinous neoplasms. Therefore, an aggressive surgical approach has mainly been recommended for all MD-IPMNs. However, the surgical management of BD-IPMNs has been controversial and the consensus guidelines are not specific for an indicator of malignancy in BD-IPMNs. The objective of this study was to determine the proper management and follow-up strategy of BD-IPMNs. METHODS: We monitored and analysed patients with presumed BD-IPMNs between March 1995 and March 2010. RESULT: The mean value of the initial cyst size in all patients with BD-IPMNs was 2.19 cm. Amongst 194 patients with BD-IPMNs, 34 underwent immediate surgical resection, 152 were followed conservatively. Amongst the 152 conservatively managed patients, 18 (11.8%) underwent surgical resection after a median follow-up of 12.7 months (range, 3-48 months). In 132 patients who were managed conservatively without surgery, the mean incremental rate of cyst size growth was 0.0038 cm/month during a median of 30.7 months of follow-up and there were no IPMN-related deaths. CONCLUSION: Amongst patients with BD-IPMNs, about 10% have surgery within approximately 1 year from the time of diagnosis because of the occurrence of new malignant stigmata. Therefore, a conservative approach without surgery and careful follow-up every 3 months or 6 months during the first year after diagnosis can be safely advocated in patients with BD-IPMNs larger than 10mm in size who have no risk factors for malignant IPMNs.

Is health screening beneficial for early detection and prognostic improvement in pancreatic cancer?

BACKGROUND/AIMS: The aim of this study was to evaluate the usefulness of health screening for early detection and improved prognosis in pancreatic cancer. METHODS: Between 1995 and 2008, 176,361 examinees visited the Health Promotion Center (HPC). Twenty patients diagnosed with pancreatic cancer were enrolled. During the same period, 40 patients were randomly selected from 2,202 patients diagnosed with pancreatic cancer at the Out Patient Clinic (OPC) for comparison. RESULTS: Within the HPC group, 10 patients were initially suspected of having pancreatic cancer following abnormal ultrasonographic findings, and 9 patients had suspected cases following the detection of elevated serum CA 19-9. The curative resection rate was higher in the HPC group than in the OPC group (p=0.011). The median survival was longer in the HPC group than in the OPC group (p=0.000). However, there was no significant difference in the 3-year survival rate between the two groups. Asymptomatic patients (n=6/20) in the HPC group showed better curative resection and survival rates than symptomatic patients. However, the difference was not statistically significant. CONCLUSIONS: Health screening is somewhat helpful for improving the curative resection rate and median survival of patients with pancreatic cancer detected by screening tests. However, the benefit of this method in improving long-term survival is limited by how early the cancer is detected.

Predictive factors associated with malignancy of intraductal papillary mucinous pancreatic neoplasms.

AIM: To identify preoperative predictive factors associated with malignancy of intraductal papillary mucinous neoplasms (IPMNs) of the pancreas. METHODS: Between April 1995 and April 2010, 129 patients underwent surgical resection for IPMNs at our institute and had confirmed pathologic diagnoses. The medical records were retrospectively reviewed and immunohistochemical staining for mucin (MUC) in pancreatic tissues was performed. RESULTS: Univariate analysis showed that the following five variables were closely associated with malignant IPMNs preoperatively: absence of extrapancreatic malignancy; symptoms; tumor size > 4 cm; main pancreatic duct (MPD) size > 7 mm; and lymph node enlargement on preoperative computed tomography (CT). Multivariate analysis revealed that the following two factors were significantly associated with malignant IPMNs preoperatively: MPD size > 7 mm [odds ratio (OR) = 2.50]; and lymph node enlargement on preoperative CT (OR = 3.57). No significant differences in the expression of MUC1, MUC2 and MUC5AC were observed between benign and malignant IPMNs. CONCLUSION: MPD size > 7 mm and preoperative lymph node enlargement on CT are useful predictive factors associated with malignancy of IPMNs.

Endocardial fibroelastosis in a 57-year-old transplant recipient.

Endocardial fibroelastosis (EFE) is characterized by deposition of collagen and elastin leading to ventricular hypertrophy and diffuse endocardial thickening. Here we report (for the first time in Korea) the case of a EFE presenting with heart failure. The patient was a 57-year-old woman who had complained of dyspnea on exertion {New York Heart Association (NYHA) functional class 3} and abdominal distension at the time of hospital admission. Echocardiography showed severe diastolic dysfunction with normal systolic function. On MRI, the contrast-enhanced delayed myocardial image demonstrated hyperenhancement in the endocardium. Owing to progressive heart failure, the patient was transplanted. Histological examination of the explanted heart showed irregularly thickened endocardium with fibrosis and elastosis in the both ventricles, compatible with the diagnosis of EFE.