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Free energy function of dislocation densities by large scale atomistic simulation
Christoph Begau,Godehard Sutmann,Alexander Hartmaier
Physics , 2015,
Abstract: This paper discusses the free energy of complex dislocation microstructures, which is a fundamental property of continuum plasticity. In the past, multiple models of the self energy of dislocations have been proposed in the literature that partially contradict each other. In order to gain insight into the relationship between dislocation microstructures and the free energy associated with them, instead of deriving a model based on theoretical or phenomenological arguments, here, these quantities are directly measured using large scale molecular dynamics simulations. Plasticity is induced using nanoindentation that creates an inhomogeneous distribution of dislocations as the result of dislocation nucleation and multiplication caused by the local deformation. Using this approach, the measurements of dislocation densities and free energies are ab-initio, because only the interatomic potential is defining the reaction of the system to the applied deformation. The simulation results support strongly a linear relation between the scalar dislocation density and the free energy, which can be related very well to the classical model of mechanical energy of straight dislocations, even for the complex dislocation networks considered here.
Full-thickness chest wall resection for locally recurrent breast cancer
Friedel, Godehard,Kuipers, Thomas,Engel, Corinna,Schopf, Christine
GMS Thoracic Surgical Science , 2005,
Abstract: Aim: In spite of available recommendations, therapeutic procedures of locally recurrent breast cancer are very different. In a retrospective study, the possibilities and results of complete, full-thickness chest wall resection are presented.Methods: Between 1985 and 2004, 51 women underwent complete, full-thickness chest wall resection with primary coverage. Primary surgical therapy of breast cancer had been mastectomy in 88%. Median age of patients undergoing surgery for a local recurrence was 57 (29 - 81) years. The median interval between surgery of the primary tumour and of the local recurrence was 70.3 (10.7 - 327.2) months; median follow-up was 29.4 (1.8 - 230.9) months. 40 (78.4%) patients required rib resections, 15 (29.4%) of them in combination with partial sternal resection. In 4 (7.8%) patients complete and in 7 (13.7%) patients partial sternal resection without additional rib resection were performed.Coverage was mainly realized using latissimus dorsi myocutaneous flaps (n=44; 86.3%). Survival rates were calculated by means of the Kaplan-Meier method, the relative risk using univariate and multivariate Cox-regression analysis.Results: In the total collective, cumulative 5-, 10- and 15-year survival (YS) rates were 39%, 31% and 23%, respectively, median survival 46.4 months. R0 resection was associated with a 5-YS of 42%. Prognostic factors were age at the time of primary surgery, disease-free interval and tumour invasion of bony structures. Mortality was 2%, morbidity 35%.Conclusion: Full-thickness chest wall resection of locally recurrent breast cancer is possible in almost any patient when performed by a team of thoracic and plastic surgeons. Only radical resection provides good long-term results with low mortality and morbidity.
Long-term results after 110 tracheal resections
Friedel, Godehard,Kyriss, Thomas,Leitenberger, Andrea,Toomes, Heikki
GMS German Medical Science , 2003,
Abstract: Objective: Among the many therapeutic options for treating tracheal stenosis (e.g. bouginage, laser resection and stenting), segmental resection and reconstruction with end-to-end anastomosis is the method of choice. We verified this in an analysis of clinical material. Patients and methods: We retrospectively evaluated 110 tracheal sleeve resections performed between 1985 and 2001. Data before and after resection were analyzed, and the patients were interviewed. Results: The aetiology of stenosis was mainly postintubation injury (n = 92) (83.6%), followed by goiter with malacia (n = 8) (7.3%) and tumor (n = 6) (5.5%). There were a few other causes (n = 3) (2.7%). 48 patients (43.6%) had undergone prior conservative or surgical treatment other than sleeve resection. A cervical approach was used in 93 (84.6%), a cervicomediastinal in 15 (13.6%), and a transthoracic in two. Healing of anastomosis was uncomplicated in 101 patients (91.8%). Major and minor complications occurred in 29 patients (26.4); there were 4 dehiscences (3.6%), 3 restenoses (2.7%), 2 suture line granulations (1.8%) and 4 vocal cord dysfunctions (3.6%). The 30-day mortality rate was 0.9%. 77 patients were interviewed after surgery (median 80.1 months); 93.5% (n = 72) were satisfied with the surgical treatment. Conclusions: Resection and reconstruction offer the best treatment for tracheal stenosis. Lethal complications were due to severe comorbidity. Many patients today still undergo unsuccessful conservative treatment before being referred to surgery.
Systematic Video-Assisted Mediastinoscopic Lymphadenectomy (VAMLA)
Hürtgen, Martin,Friedel, Godehard,Witte, Biruta,Toomes, Heikki
GMS Thoracic Surgical Science , 2005,
Abstract: Accurate mediastinal lymph node dissection during thoracotomy is mandatory for staging and for adjuvant therapy in lung cancer. Pre-therapeutic staging for neoadjuvant therapy or for video assisted thoracoscopic resection of lung cancer is achieved usually by CT-scan and mediastinoscopy. However, these methods do not reach the accuracy of open nodal dissection. Therefore we developed a technique of radical video-assisted mediastinoscopic lymphadenectomy (VAMLA). This study was designed to show that VAMLA is feasible and that radicality of lymphadenectomy is comparable to the open procedure.In a prospective study all VAMLA procedures were registered and followed up in a database. Specimens of VAMLA were analysed by a single pathologist. Lymph nodes were counted and compared to open lymphadenectomy. The weight of the dissected tissue was documented. In patients receiving tumour resection subsequently to VAMLA, radicality of the previous mediastinoscopic dissection was controlled during thoracotomy.37 patients underwent video-assisted mediastinoscopy from June 1999 to April 2000. Mean duration of anaesthesia was 84.6 (SD 35.8) minutes.In 7 patients radical lymphadenectomy was not intended because of bulky nodal disease or benign disease. The remaining 30 patients underwent complete systematic nodal dissection as VAMLA.18 patients received tumour resection subsequently (12 right- and 6 left-sided thoracotomies). These thoracotomies allowed open re-dissection of 12 paratracheal regions, 10 of which were found free of lymphatic tissue. In two patients, 1 and 2 left over paratracheal nodes were counted respectively. 10/18 re-dissected subcarinal regions were found to be radically dissected by VAMLA. In 6 patients one single node and in the remaining 2 cases 5 and 8 nodes were found, respectively. However these counts also included nodes from the ipsilateral main bronchus. None of these nodes was positive for tumour.Average weight of the tissue that was harvested by VAMLA was 10.1 g (2.2-23.7, SD 6.3). An average number of 20.5 (6-60, SD 12.5) nodes per patient were counted in the specimens. This is comparable to our historical data from open lymphadenectomy.One palsy of the recurrent nerve in a patient with extensive preparation of the nerve and resection of 11 left-sided enlarged nodes was the only severe complication in this series.VAMLA seems to accomplish mediastinal nodal dissection comparable to open lymphadenectomy and supports video assisted surgery for lung cancer. In neoadjuvant setting a correct mediastinal N-staging is achieved.
Morbidity and mortality after pneumonectomy in smokers with NSCLC
Kirschbaum, Andreas,Kyriss, Thomas,Dippon, Jürgen,Friedel, Godehard
GMS Thoracic Surgical Science , 2008,
Abstract: Objective: Perioperative morbidity and mortality in patients receiving pneumonectomy because of non-small cell lung cancer (NSCLC) remains quite high. The aim of this study is to identify risk factors to minimize perioperative mortality and morbidity.Patients and method: The results of 156 Patients who received pneumonectomy between 1995 and 2004 were reviewed retrospectively. All patients had stage I or II NSCLC. In 81 cases a right sided and in 75 a left sided pneumonectomy was performed. Cardiopulmonary function tests were sufficient for pneumonectomy.Results: Overall perioperative 30-day mortality was 7.1% (n=11), in hospital mortality 8.3% (n=13). The cause was sepsis in 6 cases, cardiac failure in 4 cases, and respiratory insufficiency in 3 cases. In univariable and multivariable regression analysis considering mortality, none of the prognostic factors reached significance. The odds ratio for postoperative death was 1.6 fold for smokers in comparison to non smokers. Complications after pneumonectomy were seen in 34.6%, with arrhythmia in 16.0%, sepsis in 1.9% and bronchopleural fistula (BPF) occurring in 6.4%. Smoking and intraoperative blood loss >500 ml were highly significant perioperative risk factors.Conclusion: Smoking until operation and intraoperative blood loss were independent postoperative risk factors leading to complications after pneumonectomy for NSCLC. The risk for complications was 2.8-fold higher for smokers.
Sympathectomy for thrombangiitis obliterans of the hands (Buerger’s disease)
Kyriss, Thomas,Steger, Volker,Friedel, Godehard,Toomes, Heikki
Thoracic Surgical Science , 2004,
Abstract: Thrombangiitis obliterans (Buerger's disease) is an inflammatory, occlusive disease, which commonly affects the small- and medium-sized extremity vessels. The precise etiology of this, especially in Europe rare disease, is unknown; however there is a strong correlation to the use of tobacco. Up to now no standardised medical treatment exists and surgical revascularization is generally ruled out. We present two young smokers, suffering from finger tip necrosis. In both cases medical treatment failed and amputation was supposed to be done. Ischemic ulcers healed after thoracoscopic sympathectomy in one case; the fingers of the other patient, who continued smoking, had to be amputated. Sympathectomy is an effective treatment option for pain at rest and ischemic ulcers if medical treatment failed. The decisive prognostic factor is the successful therapy of tobacco dependence; surgeons should consider this as important as the operative treatment.
Quality management in Thoracic Surgery for the surgical treatment of lung cancer: results of a pilot trial
Friedel, Godehard,Graeter, Thomas,Haas, Viktor,Hammelrath, Holger
Thoracic Surgical Science , 2004,
Abstract: Lung Cancer still is the major cause of death in malignant diseases. For several years the German Society for Thoracic Surgery attempted to establish an external quality management for the surgical treatment of lung cancer. Despite positive expert opinions and several negotiations no governmental support could be achieved. Therefore a pilot trial was started with financial support from the German Society for Thoracic Surgery and from the Association for Quality Management of Pneumology and Thoracic Surgery. During 2001 data of patients operated for lung cancer were prospectively recorded. Six high volume centres were prepared to participate. Mortality and morbidity rate as well as rate of sleeve resections and mediastinoscopies were selected as quality criteria. For the evaluation percentage and appropriate confidence intervals were used. 1494 interventions in 1099 patients were recorded. The type of resection was lobectomy in 565 (38%) cases, pneumonectomy in 148 (10%) cases and other interventions in 781 (52%) cases. Complications occurred in 31% of lobectomies and pneumonectomies with variations between the hospitals between 20% and 44%. Hospital mortality was 2.8% (1.5-3.5%) for the whole group. For lobectomies the hospital mortality was 2.6%, for pneumonectomies 8.1% (4-33%). The rate of mediastinoscopies in the hospitals varied between 20% and 80%. On the basis of the selected indicator and the quality criteria it could be shown that a quality management is possible.
Persisting right-sided chylothorax in a patient with chronic lymphocytic leukemia: a case report
Godehard A Scholz, Horia Sirbu, Sabine Semrau, Katharina Anders, Andreas Mackensen, Bernd M Spriewald
Journal of Medical Case Reports , 2011, DOI: 10.1186/1752-1947-5-492
Abstract: We present the case of a 65-year-old male Caucasian patient with right-sided chylothorax caused by a concomitantly diagnosed chronic lymphocytic leukemia. As first-line treatment four cycles of an immunochemotherapy, consisting of fludarabine, cyclophosphamide and rituximab were administered. In addition, our patient received total parenteral nutrition for the first two weeks of treatment. Despite the very good clinical response of the lymphoma to treatment, the chylothorax persisted and percutaneous radiotherapy of the thoracic duct was applied. However, eight weeks after the radiotherapy the chylothorax still persisted and our patient agreed to a surgical intervention. A ligation of the thoracic duct via a muscle sparing thoracotomy was performed, resulting in a complete cessation of the pleural effusion. Apart from the first two weeks our patient was treated on an out-patient basis for nearly six months.In this case of chylothorax caused by chronic lymphocytic leukemia, immunochemotherapy in combination with conservative treatment, and even consecutive radiotherapy, were not able to stop pleural effusion, despite the very good clinical response of the chronic lymphocytic leukemia to treatment.Out-patient management using repetitive thoracocenteses can be safe as bridging until definitive surgical ligation of the thoracic duct.Chylothorax is a rare condition defined by chyle entering the pleural space, caused by a disruption or blockade of the thoracic duct [1]. The pleural effusion is usually of milky white appearance due to a high lipid concentration. To distinguish chylothorax from nonchylous effusions, such as pseudochylothorax, the triglyceride level is determined. A triglyceride level greater than 110 mg/dL is highly suggestive of a chylous effusion. In cases where triglycerides range between 50 mg/dL and 110 mg/dL, a diagnosis of chylothorax can be made using lipid electrophoresis to detect the presence of chylomicrons [2,3].Disruption of the thoracic duct
Comparison of the collagen haemostat Sangustop? versus a carrier-bound fibrin sealant during liver resection; ESSCALIVER-Study
Christian Moench, Wolf O Bechstein, Valentin Hermanutz, Godehard Hoexter, Hanns-Peter Knaebel
Trials , 2010, DOI: 10.1186/1745-6215-11-109
Abstract: This is a multi-centre, patient-blinded, intra-operatively randomised controlled trial. A total of 126 patients planned for an elective liver resection will be enrolled in eight surgical centres. The primary objective of this study is to show the non-inferiority of Sangustop? versus a carrier-bound fibrin sealant (Tachosil?) in achieving haemostasis after hepatic resection. The surgical intervention is standardised with regard to devices and techniques used for resection and primary haemostasis. Patients will be followed-up for three months for complications and adverse events.This randomised controlled trial (ESSCALIVER) aims to compare the new collagen haemostat Sangustop? with a carrier-bound fibrin sealant which can be seen as a "gold standard" in hepatic and other visceral organ surgery. If non-inferiority is shown other criteria than the haemostatic efficacy (e.g. costs, adverse events rate) may be considered for the choice of the most appropriate treatment.NCT00918619All surgical procedures inevitably lead to bleeding. Haemostasis - the control of bleeding - aims at reducing the amount of blood loss and the need for transfusion as well as preventing re-bleeding, haematoma formation with subsequent morbidities, and the need for intervention or repeat surgery. During liver resection the control of bleeding is a major concern. The liver is predisposed to a diffuse bleeding because of its extreme vascularity, particularly because of the hepatic sinusoidal structure, which does not have smooth muscles capable of contraction to induce vasoconstriction.Surgical techniques and devices to facilitate haemostasis have been developed in the last decades and have minimised operative risks of liver resection. Nevertheless, a parenchymal transsection of the liver tissue is always associated with some degree of bleeding due to the division of small blood vessels which can not be isolated and ligated.In order to achieve control over that parenchymatic diffuse bleeding from th
Semidilute Polymer Solutions at Equilibrium and under Shear Flow
Chien-Cheng Huang,Roland G. Winkler,Godehard Sutmann,Gerhard Gompper
Physics , 2011, DOI: 10.1021/ma101836x
Abstract: The properties of semidilute polymer solutions are investigated at equilibrium and under shear flow by mesoscale simulations, which combine molecular dynamics simulations and the multiparticle collision dynamics approach. In semidilute solution, intermolecular hydrodynamic and excluded volume interactions become increasingly important due to the presence of polymer overlap. At equilibrium, the dependence of the radius of gyration, the structure factor, and the zero-shear viscosity on the polymer concentration is determined and found to be in good agreement with scaling predictions. In shear flow, the polymer alignment and deformation are calculated as a function of concentration. Shear thinning, which is related to flow alignment and finite polymer extensibility, is characterized by the shear viscosity and the normal stress coefficients.
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