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Open access

Marta Pawlak, Marcin Bizukojć and Stanisław Ledakowicz

Impact of bioreactor scale on lovastatin biosynthesis by Aspergillus terreus ATCC 20542 in a batch culture

Biosynthesis of lovastatin (a polyketide metabolite of Aspergillus terreus) in bioreactors of different working volume was studied to indicate how the change of scale of the process influences the formation of this metabolite. The experiments conducted in shake flasks of 150 ml working volume allowed to obtain lovastatin titres at the level of 87.5 mg LOV l-1, when two carbon sources, namely lactose and glycerol were used. The application of the same components in a large stirred-tank bioreactor of 5.3-litre working volume caused a decrease of lovastatin production by 87% compared to the shake flask culture. The deficiency of nitrogen in this bioreactor did not favour the formation of lovastatin, in contrast to the small bioreactor of 1.95-litre working volume, in which lovastatin titres comparable to those in the shake flasks could be achieved, when organic nitrogen concentration was two-fold decreased. When the control of pH and/or pO2 was used simultaneously, an increase in lovastatin production was observed in the bioreactors. However, these results were still slightly lower than lovastatin titres obtained in the shake flasks.

Open access

Marta Siemieniec, Hanna Kierzkowska-Pawlak and Andrzej Chacuk

Reaction Kinetics of Carbon Dioxide in Aqueous Diethanolamine Solutions Using the Stopped-Flow Technique

The pseudo-first-order rate constants (kOV) for the reactions between CO2 and diethanolamine have been studied using the stopped-flow technique in an aqueous solution at 293, 298, 303 and 313 K. The amine concentrations ranged from 167 to 500 mol·m-3. The overall reaction rate constant was found to increase with amine concentration and temperature. Both the zwitterion and termolecular mechanisms were applied to correlate the experimentally obtained rate constants. The values of SSE quality index showed a good agreement between the experimental data and the corresponding fit by the use of both mechanisms.

Open access

Hanna Kierzkowska-Pawlak, Marta Siemieniec and Andrzej Chacuk

Reaction kinetics of CO2 in aqueous methyldiethanolamine solutions using the stopped-flow technique

The kinetics of the reaction between CO2 and methyldiethanolamine in aqueous solutions have been studied using the stopped-flow technique at 288, 293, 298 and 303 K. The amine concentration ranged from 250 to 875 mol·m-3. The overall reaction rate constant was found to increase with amine concentration and temperature. The acid base catalysis mechanism was applied to correlate the experimentally determined kinetic data. A good agreement between the second order rate constants for the CO2 reaction with MDEA computed from the stopped-flow data and the values reported in the literature was obtained.

Open access

Marta Pawlak and Marcin Bizukojć

A kinetic model to describe lovastatin biosynthesis by Aspergillus terreus ATCC 20542 in a batch culture with the simultaneous use of lactose and glycerol as carbon sources was developed. In order to do this the kinetics of the process was first studied. Then, the model consisting of five ordinary differential equations to balance lactose, glycerol, organic nitrogen, lovastatin and biomass was proposed. A set of batch experiments with a varying lactose to glycerol ratio was used to finally establish the form of this model and find its parameters. The parameters were either directly determined from the experimental data (maximum biomass specific growth rate, yield coefficients) or identified with the use of the optimisation software. In the next step the model was verified with the use of the independent sets of data obtained from the bioreactor cultivations. In the end the parameters of the model were thoroughly discussed with regard to their biological sense. The fit of the model to the experimental data proved to be satisfactory and gave a new insight to develop various strategies of cultivation of A. terreus with the use of two substrates.

Open access

Marta Pawlak, Beata Wnuk, Daniela Kowalicka and Aleksandra Rosłoniec

Abstract

Introduction: Children with cerebral palsy (CP) in the form of spastic hemiplegia experience numerous difficulties concerning an affected upper limb such as reaching for objects, gripping or manipulating them. These limitations affect their everyday activity. Conducting an effective and simultaneously an interesting therapy aimed at meeting the child’s individual needs and improving upper limb function is a challenge for a physiotherapist. The aim of the study was to assess the effectiveness of upper limb therapy carried out within the project titled “The Pirate Group” based on Constraint-Induced Movement Therapy (CIMT) and Bimanual Training (BIT) conducted in a specially arranged environment. Material and methods: The research included 16 children with CP in the form of spastic hemiplegia. Mean age of the study participants was 4.23 years. The children underwent a two-week Constraint-Induced Movement Therapy (CIMT) combined with Bimanual Training (BIT). In order to evaluate the effects of the therapy, each child underwent the Assisting Hand Assessment (AHA) prior to the therapy and after its completion. Results: Statistical analysis revealed a significant difference (p<0.05) between the results of AHA prior to and after the therapy (t(14)=9.12, p<0.0001). An improvement in the affected upper limb function was noted in all the children participating in the research. Conclusions: The project titled “The Pirate Group”, based on CIMT and BIT is an effective therapeutic intervention which improves spontaneous activity of the affected upper limb in children with hemiplegia.

Open access

Marcin Błaszczyk, Helena Hercman, Jacek Pawlak, Michał Gąsiorowski, Šárka Matoušková, Marta Aninowska, Ditta Kicińska and Andrzej Tyc

Abstract

The quality of paleoenvironmental reconstruction based on speleothem records depends on the accuracy of the used proxies and the chronology of the studied record. As far as the dating method is concerned, in most cases, the best solution is the use of the U-series method to obtain a precise chronology. However, for older periods (i.e., over 0.5 Ma), dating has become a serious challenge. Theoretically, older materials could be dated with the U-Pb dating method. However, that method requires a relatively high uranium content (minimum of several ppm), whereas typical speleothems from Poland (and all of Central Europe) have uranium concentrations below 0.1 ppm. Because the materials in Polish caves are problematic, we applied oxygen isotope stratigraphy (OIS) as a tool for speleothem dating. By using OIS as an alternative tool to create a chronology of our flowstone, it was found that the studied flowstone crystallized from 975 to 470 ka with three major discontinuities, so obtained isotopic record can be correlated with oxygen isotopic stages from MIS 24 to MIS 12. The observed isotopic variability was also consistent and confirmed with the petrographic observations of the flowstone.

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.