A Coupled FEM-BEM Approach for the Solution of the Free-Boundary Axi-Symmetric Plasma Equilibrium Problem

In this paper we present a coupled Finite Element Method – Boundary Element Method (FEM-BEM) approach for the solution of the free-boundary axi-symmetric plasma equilibrium problem. The proposed method, obtained from an improvement of the Hagenow-Lackner coupling method, allows to efficiently model the equilibrium problem in unbounded domains by discretizing only the plasma region; the external conductors can be modelled either as 2D or 3D models, according to the problem of interest. The paper explores different iterative methods for the solution of the nonlinear Grad-Shafranov equation, such as Picard, Newton-Raphson and Newton-Krylov, in order to provide a robust and reliable tool, able to handle large-scale problems (e.g. high resolution equilibria). This method has been implemented in the FRIDA code (FRee-boundary Integro-Differential Axisimmetric – https://github. om/matteobonotto/ FRIDA), together with a suitable Adaptive Integration Technique (AIT) for the computation of the source term. FRIDA has been successfully tested and validated against experimental data from RFX-mod device, and numerical equilibria of an ITER-like device.     

T cell stimulation in the absence of exogenous antigen: a T cell signal is induced by both MHC-dependent and -independent mechanisms

Mature T cells residing in peripheral lymphoid organs have frequent contact with antigen presenting cells (APC). Such contact may be required for T cell survival, but the degree to which signals in mature T cells are induced by TCR recognition of self peptide/MHC complexes is unclear. We have used induction of the early growth response gene 1 (Egr1) as an indicator of signal transduction in 3.L2 (I-Ek-restricted) T cells interacting with APC in the absence of exogenous antigen. The data show that Egr1 can be induced in 3.L2 T cells by TCR recognition of self peptides presented by I-Ek. However, a more transient induction of Egr1 can be induced in 3.L2 T cells interacting with dendritic cells derived from class II/beta2m double-deficient mice. Egr1 induction after T cell-APC contact was also observed in a freshly isolated polyclonal CD4 T cell population. The data suggest that self peptide/MHC recognition by the TCR induces a signal in T cells and that dendritic cells can also induce a more transient T cell signal by an MHC-independent mechanism.     

Gastrointestinal spindle cell tumours of the dog: histological and immunohistochemical study

To assess the relevance of spindle cell tumours in the canine gastrointestinal (GI) tract and to classify them, a retrospective study was carried out on haematoxylin and eosin-stained sections from formalin-fixed paraffin wax-embedded samples of 105 primary GI tumours. Seventeen out of 105 (16%) GI tumours were mesenchymal, 48% were epithelial and 36% were round cell tumours. Spindle cell tumours were stained by Masson trichrome, Orcein-Van Gieson and labelled immunohistochemically (vimentin, desmin, smooth muscle actin, protein S100, glial fibrillar acid protein, CD117 and MIB-1) and the histological grade, mitotic index, nuclear size and cellular density were also assessed. The 17 gastrointestinal mesenchymal tumours were classified as 10 leiomyomas (10/10 positive for desmin and smooth muscle actin; 6/10 positive for vimentin) 2 leiomyosarcomas (2/2 positive for desmin, smooth muscle actin and vimentin) and 5 gastrointestinal stromal tumours (GISTs) (5/5 positive for CD117 and vimentin; 3/5 positive for smooth muscle actin). Canine GISTs appeared as densely packed spindle cell tumours, with a diffuse, strong, cytoplasmic immunopositivity for c-kit protein (CD117). GISTs, defined as CD117-positive spindle cell or epithelioid or pleomorphic neoplasms that presumably derive from interstitial cells of Cajal, are reported in recent medical studies as the most common mesenchymal tumours of the GI tract. Our data suggest that GISTs represent a significant portion of canine GI spindle cell tumours, which can be definitely distinguished from leiomyosarcomas only by their expression of CD117.     

Acute induction of human IL-8 production by intestinal epithelium triggers neutrophil infiltration without mucosal injury

AIM: Neutrophil migration in the intestine depends on chemotaxis of neutrophils to CXC chemokines produced by epithelial cells. The goal of this project was to determine if acute induction of a CXC chemokine gradient originating from intestinal epithelial cells is sufficient to induce neutrophil influx into intact intestinal tissue. METHODS AND RESULTS: The authors developed a double transgenic mouse model with doxycycline induced human IL-8 expression restricted to intestinal epithelial cells. Doxycycline treatment of double transgenic mice for three days resulted in a 50-fold increase in the caecal IL-8 concentration and influx of neutrophils into the lamina propria. Although neutrophils entered the paracellular space between epithelial cells, complete transepithelial migration was not observed. Doxycycline treatment also increased the water content of the caecal and colonic stool, indicating dysfunctional water transport. However, the transmural electrical resistance was not decreased. Neutrophils recruited to the intestinal epithelium did not show evidence of degranulation and the epithelium remained intact as judged by histology. CONCLUSIONS: This conditional transgenic model of chemokine expression provides evidence that acute induction of IL-8 in the intestinal epithelium is sufficient to trigger neutrophil recruitment to the lamina propria, but additional activation signals are needed for full activation and degranulation of neutrophils, mucosal injury, and complete transepithelial migration.     

A case of intraductal papillary mucinous tumour following recurrent attacks of pancreatitis lasting 26 years.

We report an interesting case of a patient with neither family nor personal history for pancreatic diseases that was admitted to our department in 1982, at the age of 25 years. At that time, medical history, absence of alcohol abuse, and radiological imaging suggested a diagnosis of idiopathic chronic pancreatitis. The patient underwent a left-pancreatectomy, with histological confirmation of chronic pancreatitis. He was asymptomatic until 1988, when episodes of pain arose, requiring a pancreatico-jejunostomy. No further problems ensued until 2004 when radiological investigation following pain-related symptoms revealed enormous dilation of the pancreatic duct. A pylorus-preserving pancreaticoduodenectomy resulting in total pancreatectomy was performed. Histological examination revealed an intraductal papillary mucinous non-invasive carcinoma. Review of the previously resected specimen revealed former misdiagnosis. This tumour usually affects an elderly population and nowadays is recognised as a possible cause of chronic obstructive pancreatitis. This report represents a slippery case of misdiagnosis and demonstrates that follow-up is always mandatory following a diagnosis of idiopathic chronic pancreatitis.     

Leishmaniasis in Tuscany (Italy): VI. Canine leishmaniasis in the focus of Monte Argentario (Grosseto)

The results of a survey of canine leishmaniasis in the coastal focus of Monte Argentario (Tuscany, Italy) are reported. Of the 171 dogs examined, 41 (23.9%) were positive in the fluorescent antibody test (FAT), but only 12 (7.0%) were positive by microscopic observation of lymphatic ganglia. Of the 41 FAT positive dogs, 17 (10.0%) showed signs of the disease. The evolution of leishmaniasis over one year from the first examination showed that 88.0% of the dogs with signs died of the disease, and 36.0% of the asymptomatic dogs became patent or died; 52.0% of the asymptomatic dogs had apparently recovered. The prevalence of the disease, the geographical, age, sex and race distribution of cases, the evolution of leishmaniasis in dogs and FAT positivity are discussed.     

Electrophysiologic evaluation of athletes with Wolff-Parkinson-White syndrome: induction of supraventricular arrhythmia at rest and under exertion with transesophageal atrial electrostimulation

The most suitable approach to the athletes with WPW is controversial. Therefore 66 symptom-free athletes with WPW and without heart disease (53 M, 13 F, mean age 21.98 yrs, min 12--max 44) underwent a study protocol whose end-point was the induction of supraventricular tachyarrhythmia, i.e. atrial fibrillation or, if not possible, atrial flutter or atrial tachycardia at rest and during ergometric stress test. The athletes with shortest R-R interval between preexcited beats less than or equal to 240 ms at rest and/or less than or equal to 210 ms during exercise were judged as being at risk i.e. no fit for sport activity. The end-point was reached in 64/66 athletes (in 62 atrial fibrillation). In 4 athletes with life threatening arrhythmia induced at rest the evaluation during exercise was not performed. According to the evaluation at rest we were able to identify only 18 athletes (28.1%) as being at risk, while according to the complete study protocol 26 athletes (40.6%) were judged as such. In 23/64 athletes (36%) this judgement was discordant with the usual non invasive evaluation (i.e. Holter monitoring, ergometric stress test, ajmaline test). During induced atrial fibrillation no significant difference, was found between the percentage of preexcited beats at rest and during exercise. On the average, 40 min. are required for performance of this study protocol (if the induced arrhythmia lasts less than 5 min.). According to our results we conclude: a) the non invasive assessment of the WPW athletes is unsatisfactory; b) the induction of atrial fibrillation during exercise gives a remarkable increase of the diagnostic power with respect to the assessment only at rest; c) since it is simple to perform and not expensive (in time, staff and cost) and because of its high diagnostic yield, we regard this protocol as fundamental for the electrophysiological evaluation of WPW athletes and also suitable for systematic study of WPW patients.     

Best-buy regimen of ursodeoxycholic acid for patients with gallstones

Bedtime administration has been advocated as a strategy for reducing minimum effective dose, side effects, and costs of chenodeoxycholic acid treatment of cholesterol gallstones, but little information is available for ursodeoxycholic acid (UDCA). We prospectively determined the minimum effective dose of bedtime UDCA in 44 patients with radiolucent gallstones treated with a range of UDCA doses (4.6-17.0 mg/kg/day). The average minimum effective dose for reducing the cholesterol saturation index (SI) of gallbladder bile to a value of 0.8 was 8.4 mg/kg/day for bedtime UDCA. The greater potency of the bedtime regimen was confirmed in seven individual patients by comparison with a mealtime regimen. Cholesterol SI was reduced from 1.25 during placebo to 0.73 during 7 mg/kg/day for bedtime UDCA and to 0.81 during 10 mg/kg/day for mealtime UDCA. The effect of the bedtime regimen was not enhanced by a repeated-release tablet formulation of UDCA by comparison with UDCA in 15 patients. We conclude that the bile acid dose is reduced during bedtime UDCA administration by comparison with mealtime UDCA in individual patients and that the best-buy regimen is 8.4 mg/kg/day UDCA given at bedtime for patients with gallstones as a group. With this dose, gallstone dissolution can be supported by unsaturated gallbladder bile at minimum risk of dose-related side effects and at minimum treatment costs.