Proteasomal degradation of the intrinsically disordered protein tau at single-residue resolution.

Intrinsically disordered proteins (IDPs) can be degraded in a ubiquitin-independent process by the 20S proteasome. Decline in 20S activity characterizes neurodegenerative diseases. Here, we examine 20S degradation of IDP tau, a protein that aggregates into insoluble deposits in Alzheimer's disease. We show that cleavage of tau by the 20S proteasome is most efficient within the aggregation-prone repeat region of tau and generates both short, aggregation-deficient peptides and two long fragments containing residues 1 to 251 and 1 to 218. Phosphorylation of tau by the non-proline-directed Ca2+/calmodulin-dependent protein kinase II inhibits degradation by the 20S proteasome. Phosphorylation of tau by GSK3ß, a major proline-directed tau kinase, modulates tau degradation kinetics in a residue-specific manner. The study provides detailed insights into the degradation products of tau generated by the 20S proteasome, the residue specificity of degradation, single-residue degradation kinetics, and their regulation by posttranslational modification.

CT-guided percutaneous core-needle biopsy of pancreatic masses: comparison of the standard mesenteric/retroperitoneal versus the trans-organ approaches.

AIM: To compare the safety and efficacy of percutaneous computed tomography (CT)-guided core-needle biopsy (CNB) of pancreatic masses traversing the gastrointestinal tract or solid viscera versus trans-mesenteric and retroperitoneal approaches. MATERIALS AND METHODS: CT-guided CNB of pancreatic lesions performed between May 2004 and December 2014 were retrospectively analysed at a single centre. Biopsies were performed using 18- or 20-G needles with a coaxial system. CT images, histopathology reports, medical records, and procedural details for all patients were reviewed to evaluate the biopsy route, complications, and diagnostic accuracy. According to the routes, biopsies were divided into trans-mesenteric, retroperitoneal and trans-organ approaches for comparison. RESULTS: A total of 85 patients, who had undergone 89 CNBs for pancreatic masses were reviewed. The overall sensitivity, specificity, and accuracy of CNB for detecting malignancy via various routes were 88.8%, 100%, and 89.9%, respectively, with a complication rate of 20.2%. Trans-organ biopsies of pancreatic masses (n=22) were performed safely via a direct pathway traversing the stomach (n=14), colon (n=3), small bowel (n=2), liver (n=2), and spleen (n=1). The sensitivity, specificity, and accuracy were 90.5%, 100%, and 90.9%, respectively. In the trans-organ biopsy group, three biopsies (13.6%) resulted in minor haematomas, but no major complications occurred. There were no statistically significant differences in the diagnostic efficacy or complication rate among the different biopsy routes. CONCLUSION: Percutaneous CT-guided CNB using a trans-organ approach is a feasible technique for diagnosing pancreatic malignancy; however, as this series was small, more data is required.

Trans-organ versus trans-mesenteric computed tomography-guided percutaneous fine-needle aspiration biopsy of pancreatic masses: feasibility and safety.

AIM: To evaluate the safety and efficacy of computed tomography (CT)-guided percutaneous fine-needle aspiration biopsy (FNAB) of pancreatic masses that traverses the gastrointestinal tract or solid viscera. MATERIALS AND METHODS: From January 2002 to December 2012, 144 patients underwent 165 CT-guided biopsies of pancreatic masses. Biopsies were performed using a 21 or 22 G needle. Cytology reports, medical records, and procedure details for all patients were retrospectively reviewed to evaluate the biopsy route, complications, and diagnostic accuracy. RESULTS: Trans-organ biopsies of pancreatic masses were safely performed via a direct pathway traversing the stomach (n = 45), colon (n = 14), jejunum (n = 4), or liver (n = 5). There were five self-limiting mesenteric haematomas along the biopsy route on immediate post-procedure CT and all patients remained asymptomatic. All haematomas occurred after a trans-mesenteric approach rather than passage through abdominal organs. Three patients had acute pancreatitis. There was no significant difference in complications and diagnostic yields between the groups. The sensitivity, specificity, positive predictive value, and negative predictive value of final FNAB cytology for malignancy were 98.3%, 100%, 100% and 71.4%, respectively. The overall accuracy was 98.4%. CONCLUSION: Percutaneous FNAB using the trans-organ approach is a safe and effective technique to diagnose pancreatic malignancy.

Endovascular repair of spontaneous isolated dissection of the superior mesenteric artery.

AIM: To present our experience of the clinical management of spontaneous isolated dissection of superior mesenteric artery (SIDSMA) and analyse the clinical features, imaging findings, and treatment outcomes. MATERIALS AND METHODS: In this retrospective study, eight consecutive patients with symptomatic SIDSMA were treated in Chang Gung Memorial Hospital between April 2007 and April 2010; among these patients, six underwent endovascular stent placement. The clinical manifestations, imaging findings, endovascular stent placement outcome, and follow-up results of the patients were retrospectively analysed. RESULTS: Eight patients were diagnosed with SIDSMA by contrast-enhanced computer tomography. One patient died due to comorbidity before angiography. Six patients underwent percutaneous endovascular stent placement in the superior mesenteric artery (SMA): four patients with bare stents and two with stent grafts. Because it was not appropriate to perform stent implantation in the remaining patient, he received only conservative treatment. All seven patients had an uneventful recovery and the follow-up period was 16 month, ranging from 1 to 35 months. CONCLUSION: For patients with symptomatic SIDSMA, endovascular repair is a feasible treatment choice with a high success rate and good clinical outcome.

Imaging findings in mandibular primitive neuroectodermal tumour: a report of a rare case and review of the literature.

Primitive neuroectodermal tumours (PNETs) are aggressive undifferentiated tumours that occur mainly in the central nervous system (CNS). Reviewing the literature, only six cases of primary PNET of the mandible have been reported. These rare tumours are usually overlooked in clinical practice. An 18-year-old woman who presented with dental caries and left cheek swelling was initially diagnosed with facial cellulitis, but the swelling persisted despite adequate intravenous antibiotic therapy. Subsequent ultrasound and MR examinations revealed a tumour originating from the left mandibular ramus. The ultrasonography-guided percutaneous core needle biopsy confirmed the diagnosis of peripheral PNET. The radiographic features of mandibular PNETs are similar to those of PNETs in other regions, except for haemorrhage, necrosis and calcification. In addition, this is the first reported case with sonographic and MR images of this rare tumour, and the first case that was diagnosed based on the ultrasonography-guided percutaneous core needle biopsy. Using these image characteristics, mandibular PNETs can be diagnosed more accurately.

CT and MRI features of acinar cell carcinoma of the pancreas with pathological correlations.

AIM: To document the computed tomography (CT) and magnetic resonance imaging (MRI) features of acinar cell carcinoma of the pancreas and to correlate them with pathological findings to determine the unique imaging manifestations of this rare subtype tumour of the pancreas. MATERIALS AND METHODS: From January 1986 to August 2008, six patients (five men and one woman, mean age 61.3 years) with histologically proven acinar cell carcinoma of the pancreas underwent CT (n=6) and MRI (n=4) examinations. The imaging features of each tumour were documented and compared with pathological findings. RESULTS: The tumours were distributed in the head (n=4), body (n=1), and tail (n=1) of the pancreas. Four masses (67%) were uniformly or partially well-defined with thin, enhancing capsules. Central cystic components were found in five tumours (83%). Two tumours (33%) exhibited intratumoural haemorrhage, and one tumour (17%) had amorphous intratumoural calcification. In both CT and MRI, the tumours enhanced less than the adjacent normal pancreatic parenchyma. The signal intensity on MRI was predominantly T1 hypointense and T2 iso- to hyperintense. CONCLUSION: Acinar cell carcinoma of the pancreas has distinct imaging features, and both CT and MRI are useful and complementary imaging methods.

Endoscopic management of biliary complications after adult right-lobe living donor liver transplantation without initial biliary decompression.

OBJECTIVES: We sought to examine biliary complications in adult right-lobe living donor liver transplantation (LDLT) with duct-to-duct anastomosis (RL-LDLT-DD), evaluating the efficacy of endoscopic retrograde cholangiography (ERC) in the diagnosis and management of biliary complications following LDLT. METHODS: Ninety adult RL-LDLT-DD were performed from June 2004 to August 2007, including 21 (23.3%) cases of biliary complications. RESULTS: The endoscopic retrograde cholangiopancreatiography (ERCP) findings were stricture only (n = 8), stricture plus leakage (n = 9), and leakage only (n = 4). In the overall 13 cases of leakage, nine patients recovered after treatment by stent or endoscopic nasobiliary drainage. The time to resolution was 3.0 +/- 1.3 months with 2.2 +/- 1.3 endoscopic examinations. All bile duct complications were treated by ERC first. Among 17 cases with stricture, seven cases were successfully treated by endoscopy and three cases by percutaneous transhepatic cholangiography plus stent (PTCS). In the other seven cases, the treatment was still ongoing in five cases and two subjects died during treatment. The mean time to stricture resolution 7.2 +/- 3.3 months with 3.9 +/- 1.4 endoscopic examinations. The results of 21 cases were 5/21 mortalities (23.8%), successful ERC treatment in 9/21; (42.9%), successful PTCS treatment in 3/21 (14.3%), and ongoing ERC treatment in 5/21, (23.8%), including one case with successful ERC treatment who died of lung infection postoperatively. During follow-up (13.1 +/- 9.9 months), there was no recurrence in the stricture or leak. CONCLUSIONS: When compared with the literature, RL-LDLT-DD without biliary drainage does not increase the incidence of biliary complications. From our study, ERC and PTC play a complementary roles in the treatment of bile duct complications.

Ruptured mediastinal cystic teratoma with intrapulmonary bronchial invasion: CT demonstration.

Ruptured cystic mediastinal teratoma is rare. The diagnosis of this condition and a clear demonstration of its associated complications are important for defining the surgical approach. We report the CT findings of a case of mediastinal cystic teratoma before and after rupture. CT features of bursting of the spherical fatty compound and intrapulmonary bronchial invasion have not been previously described.

Hepatic calcification by sequelae of chronic schistosomiasis japonica: report of four cases.

Due to the elimination of intermediate hosts and the improvement of clinical care, most parasitic infections have been effectively controlled in developing countries. Recently, the increase of the worldwide tourism, especially to Mainland China, and the migration of overseas workers from endemic countries have led to more parasitic infections that should not be overlooked by physicians. Assessment of diffuse liver disease with physical examination and laboratory findings is notoriously inaccurate. Thus, physicians use liver biopsy for accurate diagnoses. We present 4 patients with hepatic schistosomiasis japonica which were diagnosed using imaging before liver biopsy. Hepatic schistosomiais japonica has a tendency to cause dystrophic calcification and fibrosis in the liver. According to the results, a combination of ultrasonography and computed tomography (CT), used to recognize characteristic calcification patterns, seem useful to physicians for accurate diagnoses. Thus, unnecessary biopsy procedures can be avoided.

A dynamic local bump system for producing synchrotron radiation with an alternating elliptical polarization.

To facilitate high-sensitivity soft X-ray magnetic circular dichroism experiments, a dynamic local bump system has been developed at the SRRC storage ring. This system was devised to vary dynamically the vertical slope of the electron beam in a bending magnet, producing, in the electron orbit plane, soft X-rays with an alternating elliptical polarization. The local bump was created by using two pairs of vertical correctors located on each side of the bending magnet. The bump strength coefficient was obtained both from calculated estimation and from measured beam-response matrices. Control electronics for proper bump strength settings were designed to incorporate the existing orbit-corrector function. A corresponding graphic user interface was implemented so that the bump amplitude could be easily adjusted. The performance of this system is presented. Disturbance on the stored electron beam orbit was observed while flipping the corrector polarity during EPBM (elliptical polarization from bending magnets) operation. A local feedback loop, developed to eliminate such disturbance on other beamlines, is also described.

An SRRC elliptically polarizing undulator prototype to examine mechanical design feasibility and magnetic field performance.

In this work, a 1 m long Sasaki-type elliptically polarizing undulator (EPU) prototype with 5.6 cm period length is used to examine the mechanical design feasibility as well as magnetic field performance. The magnetic field characteristics of the EPU5.6 prototype at various phase shifts and gap motion are described. The field errors from mechanical tolerances, magnet block errors, end field effects and phase/gap motion effects are analysed. The procedures related to correcting the field with the block position tuning, iron shimming and the trim blocks at both ends are outlined.