RESUMEN
The magnetization reversal in magnetic FePt nanoelements having Reuleaux 3D geometry is studied using micromagnetic simulations employing Finite Element discretizations. Magnetic skyrmions are revealed in different systems generated by the variation of the magnitude of the magnetocrystalline anisotropy which was kept normal to the nanoelement's base and parallel to the applied external field. The topological quantity of skyrmion number is computed in order to characterize micromagnetic configurations exhibiting skyrmionic formations. Micromagnetic configurations with a wide range of skyrmion numbers between -3 and 3 are indicative for the existence of one or multiple skyrmions that have been detected and stabilized in a range of external fields. Internal magnetic structures are shown consisting of Bloch type skyrmionic entities in the bulk altered to Néel skyrmions on the nanoelement's bottom and top base surfaces. The actual sizes of the formed skyrmions and the internal magnetization structures were computed. In particular, the sizes of the generated and persistent skyrmions were calculated as functions of the magnetocrystalline anisotropy value and of the applied external magnetic field. It is shown that the size of skyrmions is linearly dependent on the external field value. The slope of the linear curve can be controlled by the magnetocrystalline anisotropy value. The magnetic skyrmions can be created for FePt magnetic systems lacking of chiral interactions by designing the geometry-shape of the nanoparticle and by controlling the value of magnetocrystalline anisotropy.
RESUMEN
BACKGROUND: Pentoxifylline can ameliorate pancreatitis in animal models because of its anti-tumor necrosis factor properties. OBJECTIVE: Our purpose was to study the safety and efficacy of pentoxifylline in the prevention of post-ERCP pancreatitis. DESIGN: Patients due to undergo ERCP for various indications were randomized to receive pentoxifylline 400 mg orally 3 times, beginning the day before ERCP (2 and 10 pm) until the night after the procedure (6 am and 2 and 10 pm) or to receive no preventive medication. Serum amylase values were determined before and 6 and 24 hours after ERCP. Diagnosis and grading of the severity of complications was performed according to consensus criteria. PATIENTS: One hundred fifty-eight patients received pentoxifylline (group A) and 162 had no medication (group B). The groups were similar in distributions of sex, biliary sphincterotomy, pancreatography, pancreatic duct cannulations, stone extraction, stent placement, and presence of periampullary diverticulum. Group A patients were younger (mean age 63 vs 68 years, P<.05) and biliary colic was a more frequent indication (30 vs 12, P<.05). RESULTS: Nine (5.6%) patients in group A and 5 (3%) in group B had pancreatitis (2 and 1 severe, respectively; P=.28). Serum amylase values were similar in baseline and 6- and 24-hour samples. Two (1.2%) patients in group A and 7 (4.3%) in group B had hemorrhage. LIMITATIONS: This was not a double-blind trial. CONCLUSIONS: In this study pentoxifylline did not protect against post-ERCP pancreatitis or hyperamylasemia.
Asunto(s)
Enfermedades de los Conductos Biliares/terapia , Colangiopancreatografia Retrógrada Endoscópica/efectos adversos , Pancreatitis/prevención & control , Pentoxifilina/uso terapéutico , Premedicación , Anciano , Enfermedades de los Conductos Biliares/diagnóstico , Femenino , Humanos , Hiperamilasemia/prevención & control , Masculino , Persona de Mediana Edad , Esfinterotomía Endoscópica/efectos adversosRESUMEN
We determined the clinical outcome of hepatitis e antigen (HBeAg)-negative chronic hepatitis B patients treated with long-term nucleos(t)ide analog therapy starting with lamivudine. We evaluated 201 such patients treated for 3.8 +/- 1.4 years and 2 historical similar cohorts: 1 treated with interferon-alfa (n = 209) and 1 untreated (n = 195). Virological or biochemical remission rate at 48 months under lamivudine was 34% or 36%, respectively, whereas adefovir was administered in 79 patients with virological-biochemical breakthroughs or no response. Of the lamivudine-treated patients, 4 died, 1 underwent a transplantation, and another 8 developed major events, all having advanced fibrosis at baseline and all but 1 having experienced breakthroughs or no response. At 5 years, survival was 96%, and major event-free survival was 93%. The major event-free survival was significantly better in patients with than in those without virological remission under lamivudine. At the end of follow-up, both survival and major event-free survival were independently associated with type of and response to treatment, being significantly better in patients under long-term antiviral therapy or interferon sustained responders than in interferon non-sustained responders or untreated cases (5-year survival: 96% or 98% vs. 88% or 90%, respectively). In conclusion, in HBeAg-negative chronic hepatitis B, long-term nucleos(t)ide analog therapy starting with lamivudine significantly improves survival and reduces the risk of major complications, compared with interferon non-sustained responders or untreated patients. In such patients with advanced fibrosis, close follow-up for lamivudine resistance and prompt onset of additional antiviral therapy is required or the ab initio use of agent(s) with low resistance rates should be considered.