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  • Author: Łukasz Mazurkiewicz x
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Łukasz Matuszewski, Anna Matuszewska, Magdalena Jaszek, Dawid Stefaniuk, Krzysztof Grzywnowicz, Tomasz Mazurkiewicz and Izabela Polkowska

Abstract

The main aim of the study was to assess whether the presence of biphosphate pamidronate (PA) in the cement implanted into the tibial bones had any effect on the chosen biochemical markers in rat’s serum characterising homeostasis. Forty adult male Wistar rats were divided into two control groups and two experimental groups. Tibial bone of rats in the experimental groups was implanted with PA-enriched cement, whereas the bone in control-group’s rats was implanted with cement without PA. Serum activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and creatine kinase (CK) were determined three and six weeks after the surgery. Statistically significant differences in the activities of AST and CK of the rats after implantation with non-enriched cement when compared to rats given PA-enriched cement implantation, were found. Six weeks after treatment, AST levels decreased significantly in rats with PA-enriched cement, whereas rats in the control group (implanted with non-enriched cement) demonstrated a significant increase in AST activity in comparison to the same values determined after three weeks and values of PA-enriched cement rats determined after six weeks. The activities of CK were higher in rats with PA-enriched implants than in the control group three weeks after surgery, but six weeks after the treatment, rats implanted with enriched cement reached lower values than animals implanted with non-enriched cement. The use of PA in the cement had also some positive effect on the homeostasis of the rats after the surgery and a positive influence on the post operative muscle regeneration process.

Open access

Łukasz Matuszewski, Anna Matuszewska, Tomasz Mazurkiewicz, Izabela Polkowska, Magdalena Jaszek, Marcin Grąz and Jacek Gągała

Abstract

The presence of pamidronate during local use of bisphosphonates (BP)-enriched bone cement was determined. The question was whether pamidronate implanted into the bone cement is eluted. The study was performed on 10 probes of BP-enriched bone cement located in 0.9% NaCl. The probes were incubated for 3 and 6 weeks. Ion-pair HPLC was used for the detection of pamidronate. Then, capillary electrophoresis was applied for quantitative analysis of pamidronate in the 3rd and 6th week after incubation. The presence of pamidronate, eluted from BP-enriched bone cement into 0.9% NaCl solution 3 and 6 weeks after incubation, was demonstrated. These results may explain the changes in the level of cytokine RANKL and bone turnover marker osteoprotegrin in rats’ serum treated with BP-enriched bone cement 3 and 6 weeks after surgery. The possibility of effective local use of BP-enriched bone cement in veterinary medicine was underlined. The results, and the former conducted research, point out that the clinical applications of BP-enriched bone cement in vivo may have some validity in the future.

Open access

Pawel Baranowski, Roman Gieleta, Jerzy Malachowski, Krzysztof Damaziak and Lukasz Mazurkiewicz

Abstract

Materials and their development process are highly dependent on proper experimental testing under wide range of loading within which high-strain rate conditions play a very significant role. For such dynamic loading Split Hopkinson Pressure Bar (SHPB) is widely used for investigating the dynamic behavior of various materials. The presented paper is focused on the SHPB impulse measurement process using experimental and numerical methods. One of the main problems occurring during tests are oscillations recorded by the strain gauges which adversely affect results. Thus, it is desired to obtain the peak shape in the incident bar of SHPB as “smooth” as possible without any distortions. Such impulse characteristics can be achieved using several shaping techniques, e.g. by placing a special shaper between two bars, which in fact was performed by the authors experimentally and subsequently was validated using computational methods.

Open access

Jerzy Małachowski, Marian Klasztorny, Łukasz Mazurkiewicz, Damian Kołodziejczyk and Tadeusz Niezgoda

Abstract

Issues related to critical infrastructure safety is highly demanding in aspect of newly projected systems. In this paper a problem of modeling and simulation of the supporting structure behavior of critical facility (without or with proposed protective cover) loaded with a shock wave is presented. Authors assume that two different phenomena will be responsible for minimization of shock wave effects: flow around cylindrical panel and energy absorption by panel structure. In this paper research focuses on the description and analysis of the process of explosion near the supporting elements and the blast interaction with the structure.

Open access

Paweł Baranowski, Jerzy Małachowski, Łukasz Mazurkiewicz and Krzysztof Damaziak

Abstract

Split Hopkinson pressure bar (SHPB) is one of the most important and recognisable apparatus used for characterizing the dynamic behaviour of various materials. Incident pulse generated one the incident bar usually have a rectangular shape, which is proper for some materials but for others is not. Therefore, several methods of shaping the incident pulse are used for obtaining constant strain rate conditions during tests. Very often pulse shapers made of copper or similar material are implemented due to its softness properties. In this paper such material was investigated using the FE model of SHPB. Its mechanical behaviour was characterised with and without copper disc between the striker and incident bar. Numerical simulations were carried out using explicit LS-DYNA code. Two different methods were used for modelling the copper sample: typical finite Lagrangian elements and meshless Smoothed Particle Hydrodynamics (SPH) method. As a result of two techniques used axial stress-strain characteristics were compared for three different striker’s velocity with an influence of the copper pulse shaper taking into account. Finally, FE and SPH method was compared with taking into consideration: the efficiency, computer memory and power requirements, complexity of methods and time of simulation

Open access

Łukasz Mazurkiewicz, Jerzy Małachowski, Krzysztof Damaziak, Paweł Baranowski and Paweł Gotowicki

Abstract

The main objective of the study is to develop experimentally validated FE model and perform numerical analysis of layered composites made by hand lay-up techniques during tension and bending test. The research object is glass - polyester laminate made of four unidirectional layers. In order to validate the numerical models experimental test were performed. Due to the very different stiffness modulus in tension and bending loading the material properties obtained from standard test are not suitable to apply in numerical model. Significantly different behaviour compared to experimental test was obtained for tree point bending where the numerical model becomes too stiff. Simple coupons, relatively easy to manufacture presented in the paper have very low quality. The differences in actual and theoretical bending stiffness (obtained from tension stiffness) exceed 70%. In order to represent the actual structure the layers of the composite were divided by resin layers and also additional resin layer at the top and bottom of the model were defined. Single stage optimization process was used to adjust the material layout. After layer set-up modification very significant improvement can be seen for flexural behaviour

Open access

Pawel Baranowski, Krzysztof Damaziak, Jerzy Malachowski, Lukasz Mazurkiewicz, Henryk Polakowski, Tadeusz Piatkowski and Mariusz Kastek

Abstract

This article presents the validation process of a brake FE model by means of temperature measured on a special stand using infrared technology. Unlike many other publications, the authors try to show the interaction between measurement technology and numerical modeling rather than only nice, perfectly correlated graphs. Some difficulties in choosing and using validation parameters are also pointed out and discussed. Finally, results of FE analyses are compared with measured data, followed by explanation of applied numerical technology and estimation of validation process effectiveness.

Open access

Marek Krawczyk, Michał Grąt, Karolina Grąt, Karolina Wronka, Maciej Krasnodębski, Jan Stypułkowski, Łukasz Masior, Wacław Hołówko, Joanna Ligocka, Paweł Nyckowski, Tadeusz Wróblewski, Rafał Paluszkiewicz, Waldemar Patkowski, Krzysztof Zieniewicz, Leszek Pączek, Piotr Milkiewicz, Urszula Ołdakowska-Jedynak, Bogusław Najnigier, Krzysztof Dudek, Piotr Remiszewski, Ireneusz Grzelak, Oskar Kornasiewicz, Marcin Kotulski, Piotr Smoter, Mariusz Grodzicki, Michał Korba, Piotr Kalinowski, Michał Skalski, Krzysztof Zając, Rafał Stankiewicz, Marta Przybysz, Bartosz Cieślak, Łukasz Nazarewski, Małgorzata Nowosad, Konrad Kobryń, Michał Wasilewicz, Joanna Raszeja-Wyszomirska, Jolanta Piwowarska, Dorota Giercuszkiewicz, Joanna Sańko-Resmer, Sławomir Rejowski, Monika Szydłowska-Jakimiuk, Barbara Górnicka, Bogna Wróblewska-Ziarkiewicz, Michał Mazurkiewicz, Grzegorz Niewiński, Jacek Pawlak and Ryszard Pacho

Abstract

Liver transplantation is a well-established treatment of patients with end-stage liver disease and selected liver tumors. Remarkable progress has been made over the last years concerning nearly all of its aspects.

The aim of this study was to evaluate the evolution of long-term outcomes after liver transplantations performed in the Department of General, Transplant and Liver Surgery (Medical University of Warsaw).

Material and methods. Data of 1500 liver transplantations performed between 1989 and 2014 were retrospectively analyzed. Transplantations were divided into 3 groups: group 1 including first 500 operations, group 2 including subsequent 500, and group 3 comprising the most recent 500. Five year overall and graft survival were set as outcome measures.

Results. Increased number of transplantations performed at the site was associated with increased age of the recipients (p<0.001) and donors (p<0.001), increased rate of male recipients (p<0.001), and increased rate of piggyback operations (p<0.001), and decreased MELD (p<0.001), as well as decreased blood (p=0.006) and plasma (p<0.001) transfusions. Overall survival was 71.6% at 5 years in group 1, 74.5% at 5 years in group 2, and 85% at 2.9 years in group 3 (p=0.008). Improvement of overall survival was particularly observed for primary transplantations (p=0.004). Increased graft survival rates did not reach the level of significance (p=0.136).

Conclusions. Long-term outcomes after liver transplantations performed in the Department of General, Transplant and Liver Surgery are comparable to those achieved in the largest transplant centers worldwide and are continuously improving despite increasing recipient age and wider utilization of organs procured from older donors.