Surgical treatment in proximal bile duct cancer. A single-center experience

OBJECTIVES: The authors evaluated the experience and results of a single center in surgical treatment of proximal bile duct carcinoma. SUMMARY BACKGROUND DATA: Whenever feasible, surgery is the appropriate treatment in proximal bile duct carcinoma. To improve survival rates and with special regard to liver transplantation, the extent of surgical radicalness remains an open issue. PATIENTS AND METHODS: Retrospective analysis of 249 patients who underwent surgery for proximal bile duct carcinoma via the following procedures: resection (n = 125), liver transplantation (n = 25), and exploratory laparotomy (n = 99). Survival rates were calculated according to the Kaplan-Meier method, uni- and multivariate analysis of prognostic factors, and log rank test (p < 0.05). RESULTS: Survival rates after resection and liver transplantation are correlated with international Union Against Cancer (UICC) tumor stage (resection: overall 5-year, 27.1%; stage I and II, 41.9%; stage IV, 20.7%; liver transplantation: overall 5-year, 17.1%; stage I and II, 37.8%; stage IV, 5.8%). Significant univariate prognostic factors for survival after liver resection were lymph node involvement (N category), tumor stage, tumor-free margins, and vascular invasion; for transplantation, they were local tumor extent, N category, tumor stage, and infiltration of liver parenchyma. For resection and transplantation, a multivariate analysis showed prognostic significance of tumor stage and tumor-free margins. CONCLUSION: Resection remains the treatment of choice in proximal bile duct carcinoma. Whenever possible, decisions about resectability should be made during laparotomy. With regard to the observation of long-term survivors, liver transplantation still can be justified in selected patients with stage II carcinoma. It is unknown whether more radical procedures, such as liver transplantation combined with multivisceral resections, will lead to better outcome in advanced stages. With regard to palliation, surgical drainage of the biliary system performed as hepatojejunostomy can be recommended.     

Liver transplantation in familial amyloid polyneuropathy. Case report and review of the literature

A 59-year old male of German origin noticed exercise-independent cardiac arrhythmia two years before admission. An alanine 47 transthyretin variant of Familial Amyloid Polyneuropathy with hypertrophic cardiomyopathy, peripheral sensory-motor polyneuropathy, I, degree AV heart block was diagnosed. To diminish production and deposition of mutant transthyretin and to prevent disease progression orthotopic liver transplantation was performed. Prior to transplant the patient complained of inappetence. Postoperatively, he received a chemically defined enteral nutrition regime that was discontinued after 30 months until return of appetite and weight gain indicated marked improvement. However, a duodenal biopsy still demonstrated amyloid deposits 24 months after transplantation. Echocardiographic findings remained unchanged. Neurologic examination showed an improvement of sensory-motor polyneuropathy with regression of electromyographic changes. Only traces of variant transthyretin were detectable in plasma samples taken 12 months after the operation. During the 3 year follow-up, no additional symptoms have occurred and progression of amyloidosis was prevented. Currently, orthotopic liver transplantation is the only specific treatment to prevent progression of familial amyloid polyneuropathy.     

Xanthoma disseminatum with marked mucocutaneous involvement

HISTORY AND CLINICAL FINDINGS: When aged 23 years, a now 36-year-old man was first diagnosed as having xanthomas on the upper arms and shoulders. Xanthomas then progressed, affecting both the skin and the laryngo-pharyngeal mucosa. They were so marked that several laser-surgical interventions for their removal in the phayngo-laryngeal tract were necessary to ensure unimpaired breathing. There were also extensive confluent symmetrical cutaneous xanthomas over the upper and lower arms, the face, neck and trunk. Xanthomas and scars in the pharynx and larynx necessitated marked nasal breathing. INVESTIGATIONS: There was no laboratory evidence of abnormal lipid metabolism. The concentrations of cholesterol, triglycerides, lipoprotein (a), apolipoprotein A-1, apolipoprotein B, apolipoprotein E phenotype and steroles were all normal. The biochemical composition of LDL, VLDL and HDL particle was also unremarkable. Histological examination of resected xanthomas revealed dense infiltrations of the interstitial spaces by foam-cell histiocytes with multiple lipid vacuoles, typical of xanthoma disseminatum. TREATMENT AND COURSE: Neither probucol nor cholesterol synthesis enzyme inhibitors nor glucocorticoid medication influenced the xanthomas. The only effective treatment was removal of the most unsightly or obstructing lesions. But the sars left removal in the mucocutaneous regions caused obstruction in the laryngopharyngeal tract. CONCLUSION: The cause of xanthoma disseminatum remains unknown. Skeletal muscle can also be extensively infiltrated. This case shows similarities to Erdheim-Chester disease, another are xanthomatous condition.     

Continuous workload control order release revisited: an assessment by simulation

Order release is a key component of the Workload Control concept. Jobs do not enter the shop floor directly – they are retained in a pre-shop pool and released in time to meet due dates while keeping work-in-process within limits or norms. There are two important groups of release methods: continuous methods, for which the workload falling to a specified level can trigger a release at any moment in time; and, periodic release methods, for which releases take place at fixed intervals. Continuous release methods in general have been shown to outperform periodic release methods. Yet, there is incongruence in the results presented in the literature on the relative performance of the various continuous release methods. We use a job shop simulation model to examine the performance of continuous release methods from the literature and find that the contradictory results are explained by the different rules applied to sequence jobs in the pool – a factor neglected in previous work. Finally, a new breed of continuous release methods has recently emerged, but these have not been compared with prior approaches. Therefore, we also examine these methods and show that they significantly improve overall performance, although this is to the detriment of jobs with large processing times.     

Prevention and mitigation of severe accident developments and recriticalities in advanced fast reactor systems

GEN-IV nuclear systems, especially advanced sodium-cooled fast reactors (SFRs) are on the horizon and a key issue of their success is the promise of a higher and improved safety level. In Europe safety investigations are currently under way e.g. in the collaborative CP-ESFR project of the EU. Both on the prevention and mitigation side significant efforts are invested to fulfill the high safety goals. One route of assurance concentrates on the mitigation or even elimination of specific severe accident routes leading to core disruption and recriticalities. The accident phase with larger disrupted and molten fuel regions is coined the transition phase. A competition between fuel losses and in-pool material motion exists deciding over recriticalities and energetics potentials in this phase. To get a control of the transition phase recriticalities and energetics, ideas have been developed to install dedicated means in the core that enhance and guarantee a sufficient and timely fuel discharge - a controlled material relocation (CMR). Several proposals are under way to accomplish this CMR and especially in Japan significant theoretical and experimental work has been performed. In Europe the path to develop CMR measures was driven in the past by the development of the CAPRA reactors with a high Pu enrichment. In the current paper the status of analyses is described and some new concepts are discussed. The CMR measures are discussed along two accident scenarios, the unprotected loss of flow (ULOF) and the instantaneous blockage accident (TIB).     

Intelligent Mutation Rate Control in an Economic Application of Genetic Algorithms

This work represents the first application of two-level learning in genetic algorithms in an economic environment in which the fitness value of potential rules are complementary across individuals. Two-level learning, or self-adaptation, incorporates certain strategy parameters into the representation of each individual. In this work, these strategy parameters provide the likelihood of mutation for the individual. These strategy parameters evolve by means of mutation and recombination, just as the object variables do. It is argued that self-adaptation over the parameter governing mutation can replace the election operator proposed by Arifovic (1994) in order to attain convergence to the rational expectations equilibrium. While both adaptive mutation and the election operator are sufficient for convergence, self-adaptation may be more appropriate when being compared with real-world or experimental economic data. Through analysis of a static environment it is shown that this convergence, however, will require a strong selective pressure only attained through a transformation of the baseline fitness function.     

Revisiting Individual Evolutionary Learning in the Cobweb Model – An Illustration of the Virtual Spite-Effect

We examine the Cournot oligopoly model in the context of social and individual learning. In both models of learning, firms update their decisions about how much to produce via variants of the genetic algorithm updating procedure. Arifovic (1994) found that both models of social and individual learning converged to the Walrasian, competitive equilibrium. Vriend (2000) reports that the model of social learning converges to the Walrasian equilibrium outcome, while the model of individual learning converges to the Cournot–Nash equilibrium. We revisit the issue and conduct simulations varying elements of the updating algorithms, as well as of the underlying economic model. In the analysis of the outcomes of our simulations, we conclude that the convergence to the Cournot–Nash equilibrium is due to two things: the specific way in which production rules’ performance is evaluated coupled with a specific cost function specification.      

Prognosis and comparison of performances of composite CERCER and CERMET fuels dedicated to transmutation of TRU in an EFIT ADS

The neutronic and thermomechanical performances of two composite fuel systems: CERCER with (Pu,Np,Am,Cm)O_2−x fuel particles in ceramic MgO matrix and CERMET with metallic Mo matrix, selected for transmutation of minor actinides in the European Facility for Industrial Transmutation (EFIT), were analysed aiming at their optimisation. The ALEPH burnup code system, based on MNCPX and ORIGEN codes and JEFF3.1 nuclear data library, and the modern version of the fuel rod performance code TRAFIC were used for this analysis. Because experimental data on the properties of the mixed minor-actinide oxides are scarce, and the in-reactor behaviour of the T91 steel chosen as cladding, as well as of the corrosion protective layer, is still not well-known, a set of “best estimates” provided the properties used in the code. The obtained results indicate that both fuel candidates, CERCER and CERMET, can satisfy the fuel design and safety criteria of EFIT. The residence time for both types of fuel elements can reach about 5 years with the reactivity swing within ±1000 pcm, and about 22% of the loaded MA is transmuted during this period. However, the fuel centreline temperature in the hottest CERCER fuel rod is close to the temperature above which MgO matrix becomes chemically instable. Moreover, a weak PCMI can appear in about 3 years of operation. The CERMET fuel can provide larger safety margins: the fuel temperature is more than 1000 K below the permitted level of 2380 K and the pellet-cladding gap remains open until the end of operation.