75 results on '"Procházka R"'
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2. Effects of thickness and orientation on the small scale fracture behaviour of additively manufactured Ti-6Al-4V
- Author
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Dzugan, J., Seifi, M., Prochazka, R., Rund, M., Podany, P., Konopik, P., and Lewandowski, J.J.
- Published
- 2018
- Full Text
- View/download PDF
3. Fatigue limit evaluation of structure materials based on thermographic analysis
- Author
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Prochazka, R., Dzugan, J., and Konopik, P.
- Published
- 2017
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4. Optimizing the features of the single-channel analyzer towards improvement of productivity of Mössbauer spectra
- Author
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Procházka, R., Mašláň, M., Pechoušek, J., and Jančík, D.
- Published
- 2006
- Full Text
- View/download PDF
5. Photo-induced dynamics in a pyrene–isoalloxazine(flavin)–phenothiazine triad
- Author
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Shirdel, J., Penzkofer, A., Shen, Z., Procházka, R., and Daub, J.
- Published
- 2007
- Full Text
- View/download PDF
6. Absorption and fluorescence spectroscopic characterisation of a phenothiazine–flavin dyad
- Author
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Shirdel, J., Penzkofer, A., Procházka, R., Shen, Z., and Daub, J.
- Published
- 2007
- Full Text
- View/download PDF
7. Absorption and emission spectroscopic characterisation of a pyrene-flavin dyad
- Author
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Shirdel, J., Penzkofer, A., Procházka, R., Shen, Z., Strauss, J., and Daub, J.
- Published
- 2007
- Full Text
- View/download PDF
8. Field alpha-spectroscopy of radon (222Rn) and actinon (219Rn) progeny in soil gas: Locating a radon source
- Author
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Goliáš, V., Pittauerová, D., Procházka, R., and Třískala, Z.
- Published
- 2005
- Full Text
- View/download PDF
9. Absorption and emission spectroscopic characterization of 10-phenyl-isoalloxazine derivatives
- Author
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Shirdel, J., Penzkofer, A., Procházka, R., Daub, J., Hochmuth, E., and Deutzmann, R.
- Published
- 2006
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- View/download PDF
10. Development of in vivo derived diploid and tetraploid pig embryos in a modified medium NCSU 37
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Procházka, R, Vodička, P, Zudová, D, Rybář, R, and Motlı́k, J
- Published
- 2004
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11. Partial molecular characterization and mapping of the GDF9 gene to porcine chromosome 2
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Čepica, S., Procházka, R., Civáňová, K., Knoll, A., Němcová, L., Masopust, M., Kubíčková, S., Musilová, P., and Rubeš, J.
- Published
- 2004
12. The Working Cycle of the Motoring Internal Combustion Engine by a New Method with Cylinder Pressures as in Real Engine Operation
- Author
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Procházka Radek, Dittrich Aleš, Beroun Stanislav, Zvolský Tomáš, and Voženílek Robert
- Subjects
internal combustion engine (ice) ,motoring without combustion ,mechanical losses ,thermodynamic analysis ,experiment ,Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
The current standard methods of determining the mechanical losses of the ICE by motoring do not correspond to the low pressures in the cylinders of real engine operation. The new tried and tested method of determining passive resistances by motoring ICE with high working pressures in the cylinders is based on blowing doses of compressed air into the cylinders around BDC with special self-acting valves. When motoring with the new method, the same course of pressures in the cylinders and the same load on the crank mechanism, including the piston group, is achieved during combustion. The measurement proved the problem-free functionality of the self-acting valves, and the conducted experiments provided data on the dependence of mechanical and heat losses in the ICE on the working pressures in the cylinder.
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- 2022
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13. Virtual instrumentation technique used in the nuclear digital signal processing system design: Energy and time measurement tests
- Author
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Pechousek, J., Prochazka, R., Prochazka, V., and Frydrych, J.
- Published
- 2011
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14. Photodynamics of pyrene-flavin and phenothiazine-flavin dyads.
- Author
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Shirdel, J., Penzkofer, A., Procházka, R., Shen, Z., and Daub, J.
- Published
- 2007
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15. Composite Hyaluronate-Type I Collagen-Fibrin Scaffold in the Therapy of Osteochondral Defects in Miniature Pigs.
- Author
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Filová, E., Rampichová, M., Handl, M., Lytvynets, A., Halouzka, R., Usvald, D., Hlučilová, J., Procházka, R., Dezortová, M., Rolencová, E., Košťáková, E., Trč, T., Štastný, E., Koláčna, L., Hájek, M., Motlík, J., and Amler, E.
- Subjects
OSTEOCHONDROSIS ,SWINE diseases ,OSTEONECROSIS ,GLYCOSAMINOGLYCANS ,FIBRIN - Abstract
The potential of novel scaffold containing sodium hyaluronate, type I collagen, and fibrin was investigated in the regeneration of osteochondral defects in miniature pigs. Both autologous chondrocyte-seeded scaffolds and non-seeded scaffolds were implanted into two defects located in the non-weight-bearing zone of the femoral trochlea (defect A was located more distally and medially, defect B was located more proximally and laterally). Control defects were left untreated. Twelve weeks after the operation, the knees were evaluated in vivo using MRI. Six months after the implantation, the defects were analyzed using MRI, histological, and immunohistochemical analysis. In the A defects of chondrocyte-seeded scaffold group, hyaline cartilage and fibrocartilage was formed, containing type II collagen, acidic and neutral glycosaminoglycans while the non-seeded scaffold group was predominantly filled with fibrocartilage. Defects in the control group were predominantly filled with fibrous tissue. Histomorphometric analysis of photomicrographs revealed a significantly higher amount of hyaline cartilage in the cell-seeded scaffold group in A defects than in other groups. Both scaffold groups in A defects showed significantly less fibrous tissue than cell-seeded defects B and the control group. Both histological and MRI analysis proved that the novel composite scaffold has a potential to regenerate osteochondral defects within six months. [ABSTRACT FROM AUTHOR]
- Published
- 2007
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16. Field alpha-spectroscopy of radon (222Rn) and actinon (219Rn) progeny in soil gas: Locating a radon source.
- Author
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Goliáš, V., Pittauerová, D., Procházka, R., and Třískala, Z.
- Subjects
SPECTRUM analysis ,RADON ,SOIL air ,SEMICONDUCTORS ,SPECTROMETERS ,ELECTROSTATICS - Abstract
The activities of
218 Po,214 Po and211 Bi were determined in samples obtained of soil/gas. Sampling work was taken in Jáchymov (Czech Republic) at the outcrop of the Geister-vein,by electrostatic precipitation from filtered soil gas on stainless steel disks.The samples were measured in a field laboratory using a semi-conductor alpha-spectrometer.The activities of218 Po,214 Po and211 Bi were calculated.Samples taken from active dump material (near-by radon source) exhibited a high211 Bi/214 Po ratio, while those of the vein outcrop (a relatively deeper source) had a low ratio.A mathematical model was employed to determine the radon age calculated from the actinon/radon input ratio.This varied in a range of 5.6 to -7.7 seconds.Negative age values are probably caused by the preference for actinon, which rapidly comes into equilibrium with the source of this gas. [ABSTRACT FROM AUTHOR]- Published
- 2005
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17. Paracrine and Autocrine Regulation of Cumulus Expansion in Porcine Follicles.
- Author
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Motlik, J., Procházka, R., Nagyová, E., Schellander, K., and Brem, G.
- Subjects
- *
MAMMAL reproduction , *SWINE , *PARACRINE mechanisms , *AUTOCRINE mechanisms - Abstract
Studies paracrine and autocrine regulation of cumulus expansion in porcine follicles. Production of cumulus by pig oocytes during their development; Oocytectomized complexes representing cumulus cells or by pieces of mural granulosa cells.
- Published
- 1998
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18. A Case of Haemolytic Disease of the Newborn Due to a New Red Cell Antigen, Zd.
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Švanda, M., Procházka, R., Kout, M., and Giles, Carolyn M.
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- 1970
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19. Parthenogenetic development of activated in vitro matured bovine oocytes
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Procházka, R., Durnford, R., Fiser, P.S., and Marcus, G.J.
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- 1993
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20. Behavior of pig blastomere nuclei introduced into in vitro matured ooplasm by electrically induced fusion
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Procházka, R., Smith, S., Hyttel, P., and Greve, T.
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- 1990
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21. Transcriptional activity of porcine blastomere nuclei introduced into in vitro matured ooplasm
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Hyttel, P., Procházka, R., Smith, S., Kanka, J., Greve, T., and Høier, R.
- Published
- 1990
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22. Effect of protein kinase C stimulators on activation of bovine oocytes
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Sršeň, V., Procházka, R., and Schellander, K.
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- 1997
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23. EGF stimulated expansion of porcine oocyte-cumulus complexes is affected by the size of the donor follicle
- Author
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Procházka, R., Kaláb, P., and Miyano, T.
- Published
- 1997
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24. Porcine oocytes produce CEEF only during their growth period and transition to metaphase I
- Author
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Nagyová, E., Procházka, R., and Motlík, J.
- Published
- 1997
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25. Meiotic and developmental competence of growing pig oocytes derived from small antral follicles is enhanced in culture medium containing FGF2, LIF, and IGF1 (FLI medium).
- Author
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Bartková AR, Němcová L, Kinterová V, Radová D, Strejček F, Toralová T, Laurinčík J, and Procházka R
- Subjects
- Pregnancy, Female, Animals, Swine, Oocytes metabolism, Ovarian Follicle, Meiosis, Chromatin metabolism, Fibroblast Growth Factor 2 pharmacology, Fibroblast Growth Factor 2 metabolism, In Vitro Oocyte Maturation Techniques
- Abstract
Background: Oocytes of large animal species isolated from small ovarian follicles (< 2 mm) are less competent to support early embryonic development after in vitro maturation and fertilization than their counterparts isolated from medium-sized and preovulatory follicles. This study aimed to assess the effect of a new maturation medium containing FGF2, LIF, and IGF1 (FLI medium) on the meiotic and developmental competence of pig cumulus-oocytes complexes (COCs) derived from the small and medium-sized follicles., Methods: The growing oocytes were isolated from 1 to 2 (small follicle; SF) and the fully-grown ones from 3 to 6 (large follicle; LF) mm follicles and matured in a control M199 medium with gonadotropins and EGF and the FLI medium enriched by the triplet of growth factors. The matured oocytes were parthenogenetically activated and cultured to the blastocyst stage. Chromatin configuration before and during the culture and MAP kinase activity were assessed in the oocytes. Finally, the expression of cumulus cell genes previously identified as markers of oocyte quality was assessed., Results: The maturation and blastocyst rates of oocytes gained from LF were significantly higher than that from SF in the control medium. In contrast, similar proportions of oocytes from LF and SF completed meiosis and developed to blastocysts when cultured in FLI. Most of the oocytes freshly isolated from SF possessed germinal vesicles with fine filaments of chromatin (GV
0 ) or chromatin surrounding the nucleolus (GVI ; 30%); the oocytes from LF were mainly in GVI (or GVII ) exhibiting a few small lumps of chromatin beneath the nuclear membrane. When cultured in the FLI medium for 16 h, an acceleration of the course of maturation in oocytes both from SF and LF compared to the control medium was observed and a remarkable synchrony in the course of chromatin remodeling was noticed in oocytes from SF and LF., Conclusions: This work demonstrates that the enrichment of culture medium by FGF2, LIF, and IGF1 can enhance the meiotic and developmental competence of not only fully-grown, but also growing pig oocytes and significantly thus expanding the number of oocytes available for various assisted reproductive technology applications., (© 2024. The Author(s).)- Published
- 2024
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26. How to improve pre-operative diagnostics of pancreatobiliary lesions? From immunohistochemistry to Next Generation Sequencing.
- Author
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Švajdler M, Daum O, Daumová M, Pintová J, and Procházka R
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- Humans, Biliary Tract Neoplasms diagnosis, Biliary Tract Neoplasms genetics, Biliary Tract Neoplasms pathology, Pancreatic Neoplasms diagnosis, Pancreatic Neoplasms genetics, Pancreatic Neoplasms pathology, High-Throughput Nucleotide Sequencing, Immunohistochemistry methods
- Abstract
Preoperative cytopathology of pancreatobiliary neoplastic lesions is a sensitive and specific method and is irreplaceable in the diagnosis and clinical management of these diseases. Pathologists should make every attempt to provide diagnosis as precise as possible and minimize the rate of "atypical" results, which create management dilemmas. The diagnostic accuracy of cytopathology can be significantly improved by judicious use of ancillary studies, including immunohistochemistry and molecular genetics. Next generation sequencing (NGS) is the latest addition to pancreatobiliary cytopathology diagnostic arsenal. NGS is not only a very robust diagnostic tool, but also carries significant prognostic and therapeutic information.
- Published
- 2024
27. Endoscopic treatment of complications after bariatric surgery - overview of issues and retrospective analysis of our own results.
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Nosek V, Řehoř M, Pintová J, Man M, Vraný M, and Procházka R
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- Humans, Retrospective Studies, Obesity, Morbid surgery, Endoscopy, Gastrointestinal, Bariatric Surgery adverse effects, Postoperative Complications surgery
- Abstract
Bariatric and metabolic surgery is the most invasive but also the most effective treat-ment for severe obesity and associated comorbidities. The most common procedures performed are laparoscopic sleeve gastrectomy and Roux-Y gastric bypass. Postoperative complications occur in 4-10% cases. The majority of them are mild and are treated conservatively. Complex management of severe complications often involves surgical re-intervention, which is associated with high morbidity. Technological advancements in therapeutic endoscopy expand the options for minimally invasive treatment of these complications and, in selected cases, may even be the method of choice in their management. The authors present a summary of current endoscopic procedures for managing ulcerations, leaks, fistulas, strictures, and other complications. Based on a cohort of 45 patients treated over a period of 10 years (11/2013-11/2023) at the district hospital in Jablonec nad Nisou, an overview of the endoscopic methods used, procedure numbers, duration, and outcomes of endoscopic treatment is provided. The author's commentary describes trends leading to further improvement in the outcomes of endoscopic treatment.
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- 2024
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28. Fatigue Properties of Spring Steels after Advanced Processing.
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Procházka R, Stehlík A, Kotous J, Salvetr P, Bucki T, Stránský O, and Zulić S
- Abstract
This article deals with the effect of strain-assisted tempering (SAT) on the fatigue properties of 54SiCr6 steel used for spring steel wires in a wide variety of automotive applications, including coil springs. This steel spring wire is extremely strong, having a high elastic limit and yield point, giving the steel excellent energy accumulation and fatigue properties. This combination opens up new possibilities in helical and cylindrical coil spring design, resulting in the reduction of both size and weight. Lightweight coil springs lead to improvements in fuel consumption, stability and vehicle traction. A large plastic deformation and SAT were applied to enhance the yield point of the study material. Improvements in the static and cyclic properties of steel springs were investigated using tensile tests and 3PB fatigue tests at ambient temperature. In addition, an advanced laser shock peening (LSP) process was employed to increase the fatigue resistance of the SAT material. The results presented here show great improvements in the static and fatigue properties over commercial steel treatment. The material quality of the wires was evaluated to be insufficient for further processing with cold coiling.
- Published
- 2023
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29. Extended Continuous Cooling Transformation (CCT) Diagrams Determination for Additive Manufacturing Deposited Steels.
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Halmešová K, Procházka R, Koukolíková M, Džugan J, Konopík P, and Bucki T
- Abstract
Continuous cooling transformation (CCT) diagrams are widely used when heat treating steels and represent which type of phase will occur in a material as it is cooled at different cooling rates. CCT diagrams are constructed on the basis of dilatometry measurements on relatively small testing samples (cylindrical shape with diameter of 4mm and length of 11 mm in this study). The main aim of this work was to demonstrate the possibility of evaluating the tensile test properties using mini-tensile tests from miniature volumes (1.4 × 10
-7 m3 for one sample) subsequent to determination of the CCT diagram and to extend a standard CCT diagram with information about strength, ductility and the estimated value of the work-hardening coefficient. Mini-tensile tests (MTT) were recently developed due to the low availability of experimental material and have already been successfully used for local mechanical property characterization of metals. CCT diagrams were constructed for 42CrMo4 steel prepared by the laser-directed energy deposition (L-DED) process, for commercially available 42CrMo4 steel conventionally manufactured (for comparison of traditional processing and AM preparation) and for H13 tool steel deposited by the selective laser melting (SLM) process.- Published
- 2022
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30. Fatigue properties of UFG Ti grade 2 dental implant vs. conventionally tested smooth specimens.
- Author
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Fintová S, Dlhý P, Mertová K, Chlup Z, Duchek M, Procházka R, and Hutař P
- Subjects
- Materials Testing, Surface Properties, Tensile Strength, Dental Implants, Titanium
- Abstract
Complicated geometry in combination with surface treatment strongly deteriorates fatigue resistance of metallic dental implants. Mechanical properties of pure Ti grade 2, usually used for dental implant production, were shown to be significantly improved due to intensive grain refinement via Conform SPD. The increase of the tensile strength properties was accompanied by a significant increase in the fatigue resistance and fatigue endurance limit. However, the SLA treatment usually used for the implants' surface roughening, resulted in the fatigue properties and endurance limit decrease, while this effect was more pronounced for the ultrafine-grained comparing to the coarse-grained material when tested under tensile-tensile loading mode. The testing of the implants is usually provided under the bending mode. Even though different testing condition for the conventional specimens tests and implants testing was adopted, a numerical study revealed their comparable fatigue properties. The fatigue limit determined for the implants was 105% higher than the one for coarse-grained and only by 4 % lower than the one for ultrafine-grained Ti grade 2. Based on the obtained results, conventional specimens testing can be used for the prediction of the fatigue limit of the implants., (Copyright © 2021 Elsevier Ltd. All rights reserved.)
- Published
- 2021
- Full Text
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31. The Role of MAPK3/1 and AKT in the Acquisition of High Meiotic and Developmental Competence of Porcine Oocytes Cultured In Vitro in FLI Medium.
- Author
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Procházka R, Bartková A, Němcová L, Murín M, Gad A, Marcollová K, Kinterová V, Lucas-Hahn A, and Laurinčík J
- Subjects
- Animals, Cells, Cultured, Culture Media chemistry, Female, In Vitro Oocyte Maturation Techniques veterinary, Meiosis drug effects, Meiosis physiology, Mitogen-Activated Protein Kinase 1 physiology, Oocytes cytology, Oocytes drug effects, Oogenesis drug effects, Oogenesis physiology, Proto-Oncogene Proteins c-akt physiology, Signal Transduction drug effects, Signal Transduction physiology, Swine, Culture Media pharmacology, In Vitro Oocyte Maturation Techniques methods, Mitogen-Activated Protein Kinase 3 physiology, Oocytes physiology
- Abstract
The developmental potential of porcine oocytes cultured in vitro was remarkably enhanced in a medium containing FGF2, LIF and IGF1 (FLI) when compared to a medium supplemented with gonadotropins and EGF (control). We analyzed the molecular background of the enhanced oocyte quality by comparing the time course of MAPK3/1 and AKT activation, and the expression of genes controlled by these kinases in cumulus-oocyte complexes (COCs) cultured in FLI and the control medium. The pattern of MAPK3/1 activation in COCs was very similar in both media, except for a robust increase in MAPK3/1 phosphorylation during the first hour of culture in the FLI medium. The COCs cultured in the FLI medium exhibited significantly higher activity of AKT than in the control medium from the beginning up to 16 h of culture; afterwards a deregulation of AKT activity occurred in the FLI medium, which was not observed in the control medium. The expression of cumulus cell genes controlled by both kinases was also modulated in the FLI medium, and in particular the genes related to cumulus-expansion, signaling, apoptosis, antioxidants, cell-to-cell communication, proliferation, and translation were significantly overexpressed. Collectively, these data indicate that both MAPK3/1 and AKT are implicated in the enhanced quality of oocytes cultured in FLI medium.
- Published
- 2021
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32. Internet addiction among Czech adolescents.
- Author
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Procházka R, Suchá J, Dostál D, Dominik T, Dolejš M, Šmahaj J, Kolařík M, Glaser O, Viktorová L, and Friedlová M
- Subjects
- Adolescent, Czech Republic epidemiology, Female, Humans, Internet, Male, Schools, Surveys and Questionnaires, Behavior, Addictive epidemiology, Internet Addiction Disorder
- Abstract
Our study estimates the prevalence of Internet addiction in Czech adolescents as well as differences by gender and school type. A total of 3,950 adolescents (n = 1,940 boys, n = 2,010 girls) from 11 to 19 years of age (M = 15.73, SD = 1.99) participated in the research. They completed the Internet Addiction Test, which consists of subscales for Salience, Excessive Use, Neglect Work, Anticipation, Lack of Control, and Neglect Social Life. The results indicate that adolescent girls have higher levels of internet addiction. In boys, unlike girls, internet addiction was associated with a reduction in social relationships and interactions. Our findings show interesting differences between adolescent girls and boys and the type of school attended in the Czech population in terms of Internet addiction., (© 2021 Institute of Psychology, Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.)
- Published
- 2021
- Full Text
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33. Damage tolerant design of additively manufactured metallic components subjected to cyclic loading: State of the art and challenges.
- Author
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Zerbst U, Bruno G, Buffiere JY, Wegener T, Niendorf T, Wu T, Zhang X, Kashaev N, Meneghetti G, Hrabe N, Madia M, Werner T, Hilgenberg K, Koukolíková M, Procházka R, Džugan J, Möller B, Beretta S, Evans A, Wagener R, and Schnabel K
- Abstract
Undoubtedly, a better understanding and the further development of approaches for damage tolerant component design of AM parts are among the most significant challenges currently facing the use of these new technologies. This article presents a thorough overview of the workshop discussions. It aims to provide a review of the parameters affecting the damage tolerance of parts produced by additive manufacturing (shortly, AM parts) with special emphasis on the process parameters intrinsic to the AM technologies, the resulting defects and the residual stresses. Based on these aspects, basic concepts are reviewed and critically discussed specifically for AM materials: Criteria for damage tolerant component design;Criteria for the determination of fatigue and fracture properties;Strategies for the determination of the fatigue life in dependence of different manufacturing conditions;Methods for the quantitative characterization of microstructure and defects;Methods for the determination of residual stresses;Effect of the defects and the residual stresses on the fatigue life and behaviour. We see that many of the classic concepts need to be expanded in order to fit with the particular microstructure (grain size and shape, crystal texture) and defect distribution (spatial arrangement, size, shape, amount) present in AM (in particular laser powder bed fusion). For instance, 3D characterization of defects becomes essential, since the defect shapes in AM are diverse and impact the fatigue life in a different way than in the case of conventionally produced components. Such new concepts have immediate consequence on the way one should tackle the determination of the fatigue life of AM parts; for instance, since a classification of defects and a quantification of the tolerable shapes and sizes is still missing, a new strategy must be defined, whereby theoretical calculations (e.g. FEM) allow determining the maximum tolerable defect size, and non-destructive testing (NDT) techniques are required to detect whether such defects are indeed present in the component. Such examples show how component design, damage and failure criteria, and characterization (and/or NDT) become for AM parts fully interlinked. We conclude that the homogenization of these fields represents the current challenge for the engineer and the materials scientist., Competing Interests: Declaration of interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
- Published
- 2021
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34. Adaptive and Biological Responses of Buffalo Granulosa Cells Exposed to Heat Stress under In Vitro Condition.
- Author
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Faheem MS, Ghanem N, Gad A, Procházka R, and Dessouki SM
- Abstract
The steroidogenesis capacity and adaptive response of follicular granulosa cells (GCs) to heat stress were assessed together with the underlying regulating molecular mechanisms in Egyptian buffalo. In vitro cultured GCs were exposed to heat stress treatments at 39.5, 40.5, or 41.5 °C for the final 24 h of the culture period (7 days), while the control group was kept under normal conditions (37 °C). Comparable viability was observed between the control and heat-treated GCs at 39.5 and 40.5 °C. A higher release of E2, P4 and IGF-1 was observed in the 40.5 °C group compared with the 39.5 or 41.5 °C groups. The total antioxidant capacity was higher in response to heat stress at 39.5 °C. At 40.5 °C, a significant upregulation pattern was found in the expression of the stress resistance transcripts ( SOD2 and NFE2L2 ) and of CPT2 . The relative abundance of ATP5F1A was significantly downregulated for all heat-treated groups compared to the control, while TNFα was downregulated in GCs at 39.5 °C. Expression analyses of stress-related miRNAs (miR-1246, miR-181a and miR-27b) exhibited a significant downregulation in the 40.5 °C group compared to the control, whereas miR-708 was upregulated in the 39.5 and 40.5 °C groups. In conclusion, buffalo GCs exhibited different adaptive responses, to the different heat stress conditions. The integration mechanism between the molecular and secretory actions of the GCs cultured at 40.5 °C might provide possible insights into the biological mechanism through which buffalo GCs react to heat stress.
- Published
- 2021
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35. Inhibition of miR-152 during In Vitro Maturation Enhances the Developmental Potential of Porcine Embryos.
- Author
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Gad A, Murin M, Nemcova L, Bartkova A, Laurincik J, and Procházka R
- Abstract
Oocyte developmental competence is regulated by various mechanisms and molecules including microRNAs (miRNAs). However, the functions of many of these miRNAs in oocyte and embryo development are still unclear. In this study, we managed to manipulate the expression level of miR-152 during oocyte maturation to figure out its potential role in determining the developmental competence of porcine oocytes. The inhibition (Inh) of miR-152 during oocyte maturation does not affect the MII and cleavage rates, however it significantly enhances the blastocyst rate compared to the overexpression (OvExp) and control groups. Pathway analysis identified several signaling pathways (including PI3K/AKT, TGFβ, Hippo, FoxO, and Wnt signaling) that are enriched in the predicted target genes of miR-152. Gene expression analysis revealed that IGF1 was significantly up-regulated in the Inh group and downregulated in the OvExp group of oocytes. Moreover, IGF1R was significantly upregulated in the Inh oocyte group compared to the control one and IGFBP6 was downregulated in the Inh oocyte group compared to the other groups. Blastocysts developed from the OvExp oocytes exhibited an increase in miR-152 expression, dysregulation in some quality-related genes, and the lowest rate of blastocyst formation. In conclusion, our results demonstrate a negative correlation between miR-152 expression level and blastocyst rate in pigs. This correlation could be through targeting IGF system components during oocyte development.
- Published
- 2020
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36. Local Mechanical Properties and Microstructure of EN AW 6082 Aluminium Alloy Processed via ECAP-Conform Technique.
- Author
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Procházka R, Sláma P, Dlouhý J, Konopík P, and Trojanová Z
- Abstract
An ultrafine-grained EN AW 6082 aluminum alloy was prepared by continuous serve plastic deformation (i.e., thermo-mechanical equal channel angular pressing (ECAP)-Conform process). A miniaturized tensile testing technique was used for estimating local mechanical properties with the aim to reveal the inhomogeneity of elastic and plastic properties in a workpiece volume. These inhomogeneities may appear due to the irregular shear strain distribution in a Conformed wire. Miniaturized samples for tensile testing were cut from the Conformed workpiece. Elongation of miniaturized samples was measured with a 2D digital image correlation technique as the optical extensometer. Tensile test characteristics, such as the yield strength and ultimate tensile strength, were consequently compared with results of conventional and hardness tests. The microstructure of Conformed bars was studied in the cross-section perpendicular and parallel to the extrusion direction using scanning electron microscope (SEM) and electron backscatter diffraction (EBSD) analysis. The microstructure of samples exhibits pronounced inhomogeneity, which is reflected by the hardness and tensile test results. Estimated distinctions between peripheral and central parts of the Conformed wires are probably a consequence of the significant strain differences realized in the upper and bottom wire parts.
- Published
- 2020
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37. Strain Range Dependent Cyclic Hardening of 08Ch18N10T Stainless Steel-Experiments and Simulations.
- Author
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Fumfera J, Halama R, Procházka R, Gál P, and Španiel M
- Abstract
This paper describes and presents an experimental program of low-cycle fatigue tests of austenitic stainless steel 08Ch18N10T at room temperature. The low-cycle tests include uniaxial and torsional tests for various specimen geometries and for a vast range of strain amplitude. The experimental data was used to validate the proposed cyclic plasticity model for predicting the strain-range dependent behavior of austenitic steels. The proposed model uses a virtual back-stress variable corresponding to a cyclically stable material under strain control. This internal variable is defined by means of a memory surface introduced in the stress space. The linear isotropic hardening rule is also superposed. A modification is presented that enables the cyclic hardening response of 08Ch18N10T to be simulated correctly under torsional loading conditions. A comparison is made between the real experimental results and the numerical simulation results, demonstrating the robustness of the proposed cyclic plasticity model.
- Published
- 2019
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38. Comprehensive Evaluation of the Properties of Ultrafine to Nanocrystalline Grade 2 Titanium Wires.
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Palán J, Procházka R, Džugan J, Nacházel J, Duchek M, Németh G, Máthis K, Minárik P, and Horváth K
- Abstract
This paper describes the mechanical properties and microstructure of commercially pure titanium (Grade 2) processed with Conform severe plastic deformation (SPD) and rotary swaging techniques. This technology enables ultrafine-grained to nanocrystalline wires to be produced in a continuous process. A comprehensive description is given of those properties which should enable straightforward implementation of the material in medical applications. Conform SPD processing has led to a dramatic refinement of the initial microstructure, producing equiaxed grains already in the first pass. The mean grain size in the transverse direction was 320 nm. Further passes did not lead to any additional appreciable grain refinement. The subsequent rotary swaging caused fine grains to become elongated. A single Conform SPD pass and subsequent rotary swaging resulted in an ultimate strength of 1060 MPa and elongation of 12%. The achieved fatigue limit was 396 MPa. This paper describes the production possibilities of ultrafine to nanocrystalline wires made of pure titanium and points out the possibility of serial production, particularly in medical implants.
- Published
- 2018
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39. Libet's experiment: A complex replication.
- Author
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Dominik T, Dostál D, Zielina M, Šmahaj J, Sedláčková Z, and Procházka R
- Subjects
- Adult, Electroencephalography, Electromyography, Female, Humans, Male, Self Report, Young Adult, Awareness physiology, Consciousness physiology, Contingent Negative Variation physiology, Motor Activity physiology, Psychomotor Performance physiology, Time Perception physiology, Touch Perception physiology
- Abstract
Libet's experiment is an influential classical study, which does not stop provoking heated debates. However, a full-scale replication has not been carried out to this day. Libet-style studies have usually focused on isolated ideas and concepts and never on the whole experiment in all its complexity. This paper presents detailed methodological description and results of a complex replication study. The methodology follows Libet's directions closely in most cases; when it does not, the differences are described and elaborated. The results replicate Libet's key findings, but substantial differences were found in some of the results' categories, such as the introspective reports or the number of readiness-potentials found. The discussion also addresses some current problems pertaining the methodology of the Libet-style experiments and provides some recommendations based on a detailed process evaluation., (Copyright © 2018 Elsevier Inc. All rights reserved.)
- Published
- 2018
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- View/download PDF
40. EEG data and introspective reports from the Libet׳s experiment replication.
- Author
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Dominik T, Dostál D, Zielina M, Šmahaj J, Sedláčková Z, and Procházka R
- Abstract
This article provides data from a contemporary replication of Libet׳s experiment. For the methodology, results and discussion of the replication, see the article "Libet׳s Experiment: A Complex Replication" (Dominik et al., 2018). Three types of data are presented in this article: (1) introspective reports (M, W and S), (2) EMG onset times relative to a mouse click or to the target time in tasks with a movement at pre-set time and (3) relevant averaged EEG data.
- Published
- 2018
- Full Text
- View/download PDF
41. Libet's experiment: Questioning the validity of measuring the urge to move.
- Author
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Dominik T, Dostál D, Zielina M, Šmahaj J, Sedláčková Z, and Procházka R
- Subjects
- Adult, Female, Humans, Male, Young Adult, Awareness physiology, Motor Activity physiology, Time Perception physiology, Volition physiology
- Abstract
The time of subjectively registered urge to move (W) constituted the central point of most Libet-style experiments. It is therefore crucial to verify the W validity. Our experiment was based on the assumption that the W time is inferred, rather than introspectively perceived. We used the rotating spot method to gather the W reports together with the reports of the subjective timing of actual movement (M). The subjects were assigned the tasks in two different orders. When measured as first in the respective session, no significant difference between W and M values was found, which suggests that uninformed subjects tend to confuse W for M reports. Moreover, we found that W values measured after the M task were significantly earlier than W values measured before M. This phenomenon suggests that the apparent difference between W and M values is in fact caused by the subjects' previous experience with M measurements., (Copyright © 2017 Elsevier Inc. All rights reserved.)
- Published
- 2017
- Full Text
- View/download PDF
42. Endogenously produced hydrogen sulfide is involved in porcine oocyte maturation in vitro.
- Author
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Nevoral J, Žalmanová T, Zámostná K, Kott T, Kučerová-Chrpová V, Bodart JF, Gelaude A, Procházka R, Orsák M, Šulc M, Klein P, Dvořáková M, Weingartová I, Víghová A, Hošková K, Krejčová T, Jílek F, and Petr J
- Subjects
- Animals, Blotting, Western, Female, Hyaluronic Acid chemistry, Immunohistochemistry, Oocytes enzymology, Real-Time Polymerase Chain Reaction, Swine growth & development, Hydrogen Sulfide metabolism, Oocytes growth & development, Swine physiology
- Abstract
Hydrogen sulfide, one of three known gasotransmitters, is involved in physiological processes, including reproductive functions. Oocyte maturation and surrounding cumulus cell expansion play an essential role in female reproduction and subsequent embryonic development. Although the positive effects of exogenous hydrogen sulfide on maturing oocytes are well known, the role of endogenous hydrogen sulfide, which is physiologically released by enzymes, has not yet been described in oocytes. In this study, we observed the presence of Cystathionine β-Synthase (CBS), Cystathionine γ-Lyase (CTH) and 3-Mercaptopyruvate Sulfurtransferase (3-MPST), hydrogen sulfide-releasing enzymes, in porcine oocytes. Endogenous hydrogen sulfide production was detected in immature and matured oocytes as well as its requirement for meiotic maturation. Individual hydrogen sulfide-releasing enzymes seem to be capable of substituting for each other in hydrogen sulfide production. However, meiosis suppression by inhibition of all hydrogen sulfide-releasing enzymes is not irreversible and this effect is a result of M-Phase/Maturation Promoting Factor (MPF) and Mitogen-Activated Protein Kinase (MAPK) activity inhibition. Futhermore, cumulus expansion expressed by hyaluronic acid (HA) production is affected by the inhibition of hydrogen sulfide production. Moreover, quality changes of the expanded cumuli are indicated. These results demonstrate hydrogen sulfide involvement in oocyte maturation as well as cumulus expansion. As such, hydrogen sulfide appears to be an important cell messenger during mammalian oocyte meiosis and adequate cumulus expansion., (Copyright © 2015 Elsevier Inc. All rights reserved.)
- Published
- 2015
- Full Text
- View/download PDF
43. Effect of epidermal growth factor-like peptides on pig cumulus cell expansion, oocyte maturation, and acquisition of developmental competence in vitro: comparison with gonadotropins.
- Author
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Procházka R, Petlach M, Nagyová E, and Nemcová L
- Subjects
- Animals, Cell Differentiation drug effects, Cell Differentiation genetics, Cells, Cultured, Cumulus Cells metabolism, Cumulus Cells physiology, Embryo Culture Techniques, Embryonic Development drug effects, Embryonic Development genetics, Epidermal Growth Factor chemistry, Epidermal Growth Factor pharmacology, Female, Follicle Stimulating Hormone pharmacology, Gene Expression Profiling, Oocytes metabolism, Oocytes physiology, Oogenesis drug effects, Oogenesis genetics, Parthenogenesis drug effects, Parthenogenesis genetics, Parthenogenesis physiology, Peptide Fragments chemistry, Cell Proliferation drug effects, Cumulus Cells drug effects, Gonadotropins pharmacology, Oocytes drug effects, Peptide Fragments pharmacology, Swine genetics, Swine metabolism, Swine physiology
- Abstract
The aim of this work was to assess the FSH-stimulated expression of epidermal growth factor (EGF)-like peptides in cultured cumulus-oocyte complexes (COCs) and to find out the effect of the peptides on cumulus expansion, oocyte maturation, and acquisition of developmental competence in vitro. FSH promptly stimulated expression of amphiregulin (AREG) and epiregulin (EREG), but not betacellulin (BTC) in the cultured COCs. Expression of AREG and EREG reached maximum at 2 or 4 h after FSH addition respectively. FSH also significantly stimulated expression of expansion-related genes (PTGS2, TNFAIP6, and HAS2) in the COCs at 4 and 8 h of culture, with a significant decrease at 20 h of culture. Both AREG and EREG also increased expression of the expansion-related genes; however, the relative abundance of mRNA for each gene was much lower than in the FSH-stimulated COCs. In contrast to FSH, AREG and EREG neither stimulated expression of CYP11A1 in the COCs nor an increase in progesterone production by cumulus cells. AREG and EREG stimulated maturation of oocytes and expansion of cumulus cells, although the percentage of oocytes that had reached metaphase II was significantly lower when compared to FSH-induced maturation. Nevertheless, significantly more oocytes stimulated with AREG and/or EREG developed to blastocyst stage after parthenogenetic activation when compared to oocytes stimulated with FSH alone or combinations of FSH/LH or pregnant mares serum gonadotrophin/human chorionic gonadotrophin. We conclude that EGF-like peptides do not mimic all effects of FSH on the cultured COCs; nevertheless, they yield oocytes with superior developmental competence.
- Published
- 2011
- Full Text
- View/download PDF
44. Alteration of arsenopyrite in soils under different vegetation covers.
- Author
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Mihaljevic M, Ettler V, Sebek O, Drahota P, Strnad L, Procházka R, Zeman J, and Sracek O
- Subjects
- Environmental Monitoring, Kinetics, Microscopy, Electron, Scanning, Minerals, Trees growth & development, Weather, X-Ray Diffraction, Arsenicals analysis, Iron Compounds analysis, Soil analysis, Soil Pollutants analysis, Sulfides analysis
- Abstract
The weathering of arsenopyrite (FeAsS) has been monitored in soils using an in situ experimental approach. Arsenopyrite in nylon experimental bags was placed in individual horizons in soils in spruce (litter, horizons A, B, and C), beech (litter, horizons A, B, and C) and unforested (horizons A, B, and C) areas and left in contact with the soil for a period of 1 year. The individual areas on the ridge of the Krusné hory Mts., Czech Republic, had the same lithology, climatic and environmental conditions. Scorodite (FeAsO(4).2H(2)O) was identified as a principal secondary mineral of arsenic (As) formed directly on the surface of the arsenopyrite. Scorodite was formed in all the areas in all soil horizons. The amount of scorodite formed decreased in the series beech, spruce and unforested areas. In forested areas, there was a larger amount of scorodite on arsenopyrites exposed in organic horizons (litter, A horizon). The greater rate of arsenopyrite alteration in organic horizons in the beech stand compared to spruce stand is probably a result of faster mineralization of organic material with resulting production of nitrate and better seepage conditions of soil in this area. Speciation of As determined using the sequential extraction technique demonstrated that As was bonded in the soils primarily in the residual fractions prior to the experiment. The As content in the mobile fractions increased in the organic horizon in the forested areas after the experiments.
- Published
- 2010
- Full Text
- View/download PDF
45. Development of functional LH Receptors on pig cumulus-oocyte complexes cultured in vitro by a novel two-step culture system.
- Author
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Procházka R, Nemcová L, Nagyová E, Scsuková S, and Mlynarcíková A
- Subjects
- Analysis of Variance, Animals, Bucladesine pharmacology, Cell Culture Techniques methods, Cumulus Cells cytology, Cumulus Cells drug effects, Cyclic AMP-Dependent Protein Kinases metabolism, Female, Follicle Stimulating Hormone pharmacology, Gene Expression drug effects, Glucuronosyltransferase biosynthesis, Glucuronosyltransferase genetics, Glucuronosyltransferase metabolism, Hyaluronic Acid metabolism, Luteinizing Hormone pharmacology, Oocytes cytology, Oocytes drug effects, Ovarian Follicle drug effects, Progesterone metabolism, RNA, Messenger biosynthesis, RNA, Messenger genetics, Receptors, LH genetics, Receptors, LH metabolism, Swine, Cumulus Cells metabolism, Oocytes growth & development, Ovarian Follicle metabolism, Receptors, LH biosynthesis
- Abstract
We show in the present study that freshly isolated pig cumulus-oocyte complexes (COCs) display a limited response to LH, as assessed by the expression of hyaluronan synthase 2 (Has2) mRNA, activation of protein kinase A (PKA), production of hyaluronic acid (HA) and progesterone, cumulus cell expansion and resumption of meiosis. These data indicate that freshly isolated COCs do not possess a sufficient number of functional LH receptors (LHR). However, the expression of Lhr significantly increased during the culture of COCs in vitro in a medium supplemented with FSH. Assuming that the effect of FSH on LHR induction is mediated via cAMP signaling pathways, we developed a new culture system, in which the COCs were pre-cultured for 72 hr in a medium supplemented with dbcAMP. The pre-cultured COCs remained in the germinal vesicle stage, their cumulus investment underwent a dramatic increase in size and gap junctions between the cumulus cells were preserved. The stimulation of such COCs with either FSH or LH led to the resumption and completion of meiosis, activation of PKA, expression of Has2, synthesis of large amounts of HA and progesterone, and extensive expansion of cumulus cells. We conclude that the formation of functional LHR is stimulated in cumulus cells during the culture in vitro in a cAMP-dependent pathway. The dbcAMP-treated COCs thus represent a new model in which the resumption of meiosis and cumulus expansion can be induced exclusively by the action of recombinant LH., (2009 Wiley-Liss, Inc.)
- Published
- 2009
- Full Text
- View/download PDF
46. Proteolytic activity of the 26S proteasome is required for the meiotic resumption, germinal vesicle breakdown, and cumulus expansion of porcine cumulus-oocyte complexes matured in vitro.
- Author
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Yi YJ, Nagyova E, Manandhar G, Procházka R, Sutovsky M, Park CS, and Sutovsky P
- Subjects
- Actin Cytoskeleton metabolism, Animals, Cells, Cultured, Cumulus Cells cytology, Cumulus Cells drug effects, Cytoplasm metabolism, Cytoskeleton drug effects, Dose-Response Relationship, Drug, Extracellular Matrix, Female, Gonadotropins pharmacology, Leupeptins pharmacology, Meiosis drug effects, Oocytes cytology, Oocytes drug effects, Ovarian Follicle, Cumulus Cells physiology, Meiosis physiology, Oocytes physiology, Proteasome Endopeptidase Complex metabolism, Swine
- Abstract
The resumption of oocyte meiosis in mammals encompasses the landmark event of oocyte germinal vesicle (GV) breakdown (GVBD), accompanied by the modification of cell-to-cell communication and adhesion between the oocyte and surrounding cumulus cells. The concomitant cumulus expansion relies on microfilament-cytoskeletal remodeling and extracellular matrix (ECM) deposition. We hypothesized that this multifaceted remodeling event requires substrate-specific proteolysis by the ubiquitin-proteasome pathway (UPP). We evaluated meiotic progression, cytoskeletal dynamics, and the production of cumulus ECM in porcine cumulus-oocyte complexes (COCs) cultured with or without 10-200 microM MG132, a specific proteasomal inhibitor, for the first 22 h of in vitro maturation, followed by 22 h of culture with or without MG132. Treatment with 10 microM MG132 arrested 28.4% of oocytes in GV stage (vs. 1.3% in control), 43.1% in prometaphase I, and 16.2% in metaphase I, whereas 83.7% of control ova reached metaphase II (0% of MG132 reached metaphase II). The proportion of GV-stage ova increased progressively to >90% with increased concentration of MG132 (20-200 microM). Furthermore, MG132 blocked the extrusion of the first polar body and degradation of F-actin-rich transzonal projections (TZP) interconnecting cumulus cells with the oocyte. The microfilament disruptor cytochalasin E (CE) prevented cumulus expansion but accelerated the breakdown of TZPs. Ova treated with a combination of 10 microM MG132 and 10 microM CE underwent GVBD, despite the inhibition of proteasomal activity. However, 90.0% of cumulus-free ova treated with 10 microM MG132 remained in GV stage, compared with 16.7% GV ova in control. Cumulus expansion, retention of hyaluronic acid, and the deposition of cumulus ECM relying on the covalent transfer of heavy chains of inter-alpha trypsin inhibitor (IalphaI) were also inhibited by MG132. Cumulus expansion in control COCs was accompanied by the degradation of ubiquitin-C-terminal hydrolase L3, an important regulator of UPP. RAC1, a UPP-controlled regulator of actin polymerization was maintained at steady levels throughout cumulus expansion. We conclude that proteasomal proteolysis has multiple functions in the progression of oocyte meiosis beyond GV and metaphase I stage, polar body extrusion, and cumulus expansion.
- Published
- 2008
- Full Text
- View/download PDF
47. Molecular mechanisms of insulin-like growth factor 1 promoted synthesis and retention of hyaluronic acid in porcine oocyte-cumulus complexes.
- Author
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Nemcová L, Nagyová E, Petlach M, Tománek M, and Procházka R
- Subjects
- Animals, Cell Proliferation drug effects, Cells, Cultured, Cyclic AMP biosynthesis, Cyclic AMP-Dependent Protein Kinases metabolism, Female, Follicle Stimulating Hormone pharmacology, Glucuronosyltransferase genetics, Glucuronosyltransferase metabolism, Granulosa Cells cytology, Granulosa Cells metabolism, Hyaluronan Synthases, Mitogen-Activated Protein Kinase 3 metabolism, Oocytes metabolism, Phosphatidylinositol 3-Kinases metabolism, Phosphorylation drug effects, Proto-Oncogene Proteins c-akt metabolism, Swine, Granulosa Cells drug effects, Hyaluronic Acid biosynthesis, Hyaluronic Acid metabolism, Insulin-Like Growth Factor I pharmacology, Oocytes drug effects
- Abstract
The purpose of the present study was to elucidate signaling pathways by which insulin like-growth factor 1 (IGF1) promotes FSH-stimulated synthesis and retention of hyaluronic acid (HA) in pig oocyte-cumulus complexes (OCCs) cultured in serum-free medium. We found that IGF1 had no effects on FSH-stimulated production of cAMP and activation of protein kinase A in the OCCs. Immunoblotting with phospho-specific antibodies showed that FSH moderately phosphorylated v-akt murine thymoma viral oncogene homolog (AKT) and mitogen-activated kinase 3 and 1 (MAPK3/1) in cumulus cells. The exposure of OCCs to both FSH and IGF1 resulted in a significant (P < 0.05) increase in AKT and MAPK3/1 phosphorylation. An inhibitor of phosphoinositide-3-kinase (PIK3), LY 294002, significantly (P < 0.05) reduced the IGF1-enhanced phosphorylation of AKT, and inhibitors of AKT (SH6) and MAPK3/1 (U0126) significantly (P < 0.05) decreased the synthesis and retention of HA stimulated by concomitant exposure of OCCs to both FSH and IGF1. The IGF1-promoted synthesis of HA was not accompanied by an increase in the relative abundance of hyaluronan synthase 2 (HAS2) mRNA in the cumulus cells. We conclude that IGF1 promotes the FSH-stimulated synthesis and retention of HA in pig OCCs by PIK3/AKT- and MAPK3/1-dependent mechanisms.
- Published
- 2007
- Full Text
- View/download PDF
48. A new model of corneal transplantation in the miniature pig: efficacy of immunosuppressive treatment.
- Author
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Tavandzi U, Procházka R, Usvald D, Hlucílová J, Vitásková M, Motlík J, Vítová A, Filipec M, Forrester JV, and Holán V
- Subjects
- Animals, Drug Therapy, Combination, Graft Rejection prevention & control, Graft Survival drug effects, Models, Animal, Swine, Swine, Miniature, Corneal Transplantation immunology, Corneal Transplantation methods, Immunosuppressive Agents therapeutic use
- Abstract
Corneal allograft rejection is frequently studied in small rodent or rabbit models. To study mechanisms of rejection in a model that more closely mimics transplantation in humans, we performed orthotopic corneal transplantation in the miniature pig using a 7-mm diameter donor graft. Four groups of recipients were studied: 1) untreated naive, 2) untreated vascularized (high risk), 3) high-risk grafts treated by topical application of prednisolone, or 4) high-risk grafts treated with a combined systemic immunosuppression regime of oral prednisone, cyclosporine A, and mycophenolate mofetil. Both the clinical features and histological assessment of corneal graft rejection showed close similarities to graft rejection in humans. Interestingly, preliminary results indicated that topical steroid treatment was superior to systemic immunosuppression in significantly promoting graft survival. Thus, corneal transplantation in the pig represents an animal model most closely resembling corneal grafting in humans, and offers possibilities for testing various clinically applicable immunosuppressive treatments.
- Published
- 2007
- Full Text
- View/download PDF
49. Effect of intraovarian factors on porcine follicular cells: cumulus expansion, granulosa and cumulus cell progesterone production.
- Author
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Jezová M, Scsuková S, Nagyová E, Vranová J, Procházka R, and Kolena J
- Subjects
- Animals, Calcium Channel Blockers pharmacology, Cell Division physiology, Culture Media, Conditioned, Epidermal Growth Factor pharmacology, Epidermal Growth Factor physiology, Female, Follicle Stimulating Hormone physiology, Genistein pharmacology, Granulosa Cells drug effects, Granulosa Cells metabolism, Growth Inhibitors pharmacology, Hyaluronic Acid biosynthesis, Ovarian Follicle cytology, Ovarian Follicle drug effects, Ovarian Follicle metabolism, Progesterone metabolism, Radioimmunoassay veterinary, Signal Transduction physiology, Biological Factors physiology, Granulosa Cells physiology, Ovarian Follicle physiology, Progesterone biosynthesis, Swine physiology
- Abstract
The role of granulosa cell conditioned media (CM) containing luteinization stimulator (LS), and the role of EGF in the cumulus expansion of oocyte-cumulus complexes (OCC) isolated from large antral follicles was investigated. The CM were prepared by incubation of granulosa cells isolated from large antral follicles. After 24h incubation, more than 61 or 64% of OCC expanded to the +3 and +4 stage in the presence of CM (50%) or EGF (10ng/ml), respectively. The stimulatory effect of LS and EGF on the cumulus expansion was accompanied by the enhanced hyaluronic acid synthesis. Complete suppression of cumulus expansion stimulated by LS and EGF was observed in the presence of 10 micromol/l genistein (tyrosine kinase inhibitor), in the presence of 10mmol/l LiCl (the inhibitor of inositol 1,4,5-trisphosphate metabolism), and 100 micromol/l gallopamil, verapamil and norverapamil (calcium channel blockers). Stimulatory effect of EGF on the cumulus expansion of OCC isolated from large follicles was accompanied by the increased cumulus cell progesterone production. However, EGF did not affect the progesterone production by OCC isolated from small follicles. To determine whether EGF could modulate the granulosa cell steroidogenesis also, the effect of EGF on granulosa cells isolated from large (LGC) and small (SGC) follicles was compared. EGF (10ng/ml) failed to affect the progesterone synthesis during 72h culture of SGC but significantly enhanced the LGC progesterone production. Our results indicate that luteinization factor stimulates the cumulus expansion and hyaluronic acid synthesis by the OCC isolated from large antral follicles. The mechanism of LS- and EGF-induced cumulus expansion may involve tyrosine kinase activation and calcium mobilization. In addition, these results indicate the different response of porcine cumulus and granulosa cells originating from small and large follicles on the stimulatory effect of EGF.
- Published
- 2001
- Full Text
- View/download PDF
50. Secretion of paracrine factors enabling expansion of cumulus cells is developmentally regulated in pig oocytes.
- Author
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Nagyová E, Vanderhyden BC, and Procházka R
- Subjects
- 4-Butyrolactone analogs & derivatives, 4-Butyrolactone pharmacology, Animals, Cells, Cultured, Culture Media, Conditioned, Cyclin B drug effects, Cyclin B metabolism, Cyclin-Dependent Kinases antagonists & inhibitors, Enzyme Inhibitors pharmacology, Female, Follicle Stimulating Hormone pharmacology, Histones drug effects, Histones metabolism, Hyaluronic Acid biosynthesis, Meiosis, Mice, Mice, Inbred ICR, Oocytes drug effects, Ovarian Follicle cytology, Paracrine Communication, Swine, Oocytes cytology, Oocytes physiology
- Abstract
To demonstrate secretion of cumulus expansion-enabling factor (CEEF) by porcine oocytes, we used an interspecies testing system. Porcine oocytes were used to condition culture medium, and the presence of CEEF was tested using mouse oocytectomized complexes (OOX), which require CEEF for expansion. Follicle-stimulating hormone-stimulated expansion and synthesis of hyaluronic acid (HA) by mouse OOX were assessed after 18 h of culture in media conditioned by porcine oocytes: 1) at different stages of maturation and 2) in which maturation was inhibited with a specific inhibitor of cdk-kinases, butyrolactone I. Fully grown (GV-germinal vesicle), late-diakinesis (LD), metaphase I (MI), and metaphase II (MII) oocytes were prepared by culture of oocyte-cumulus complexes (OCC) for 0, 22, 27, and 42 h, respectively. To block GV breakdown, porcine oocytes were cultured for 27 h in medium supplemented with butyrolactone I (50 microM). Medium conditioned by oocytes in GV, LD, and after butyrolactone I block allowed full expansion of >90% of mouse OOX, whereas oocytes in MI and MII caused disintegration of mouse OOX without cumulus mucification. To measure synthesis of HA by cumulus cells, 25 mouse OOX were cultured in the conditioned media in the presence of 2.5 microCi of D-[6-(3)H]glucosamine hydrochloride. After 18 h, incorporation of the [(3)H]glucosamine into HA was determined either in complexes (retained HA) or in medium plus complexes (total HA). Total HA accumulation by mouse OOX was not different from that of intact OCC. However, oocytes in GV, LD, and after butyrolactone I treatment enabled mouse OOX to retain significantly more HA within the complex than oocytes in MI and MII. The results indicate that secretion of factors that promote the retention of HA within the complex is developmentally regulated during oocyte maturation.
- Published
- 2000
- Full Text
- View/download PDF
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