Příručka pro střední školy, která obsahuje otázky z fyziky, které se zaměřují na přijímací zkoušky na vysokou školu.

• MeSH
• fyzika MeSH
• přijímací zkouška na vysokou školu MeSH
• Publikační typ
• příručky MeSH

• Konspekt
• Fyzika
• Učební osnovy. Vyučovací předměty. Učebnice
• NLK Obory
• fyzika, biofyzika
• NLK Publikační typ
• učebnice středních škol
• testy
• otázky a odpovědi

Soubor testových otázek z fyziky, který je určen pro studenty lékařství i studenty bakalářských i magisterských oborů na 2. lékařské fakultě Univerzity Karlovy.; Soubor modelových otázek a odpovědí je určen zájemcům o magisterské i bakalářské studium na 2. lékařské fakultě Univerzity Karlovy v Praze.

• MeSH
• fyzika MeSH
• přijímací zkouška na vysokou školu MeSH

• Konspekt
• Fyzika
• Učební osnovy. Vyučovací předměty. Učebnice
• NLK Obory
• fyzika, biofyzika
• NLK Publikační typ
• testy

OBJECTIVE: Improved staging of cartilage degeneration is required, particularly during the early stages. We correlated mechanical properties with histological and macroscopic findings. METHODS: One hundred and twenty cartilage samples were obtained during total knee arthroplasty. Two adjacent plugs were harvested--one for histological classification and one for macroscopic and biomechanical purposes. Dynamic impact testing was performed; normal stress, dissipated energy (∆E), tangent modulus and stiffness were evaluated. RESULTS: Samples were classified according to six categories of the ICRS histological scale. Mechanical characteristics revealing significant differences between the groups (p < 0.01) were specific damping and related absolute ∆E. A significant correlation was found between the macroscopic score and specific damping, as well as absolute and relative ∆E (p < 0.01). A strong relation was revealed between relative ∆E and cartilage thickness (p < 0.001; R (2) = 0.69). CONCLUSIONS: Only ∆E correlated with the condition of the cartilage--the value increased with decreasing quality-and is the most suitable characteristic. This change appears substantial in initial stages of cartilage deterioration.

• MeSH
• artróza kolenních kloubů patologie   patofyziologie   chirurgie   MeSH
• biomechanika MeSH
• kloubní chrupavka patologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mechanický stres MeSH
• pevnost v tlaku MeSH
• pružnost MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Hydrogels prepared from a mixture of fibrin and high-molecular weight (MW) hyaluronic acid (HA) were found to be suitable scaffolds for chondrocyte seeding and pig knee cartilage regeneration. Collagen in the hydrogels is not necessary for the formation of biomechanically stable tissue. Regenerated cartilage showed very good biomechanical and histological properties only 6 months after implantation. Notably, the quality of the healing process was dependent on the initial chondrocyte concentration of the scaffolds. These experiments were performed according to good laboratory practice (GLP).

• MeSH
• biokompatibilní materiály chemie   MeSH
• biomechanika MeSH
• chondrocyty cytologie   fyziologie   MeSH
• chondrogeneze MeSH
• chrupavka fyziologie   chirurgie   MeSH
• fibrin chemie   MeSH
• hydrogely MeSH
• kyselina hyaluronová chemie   MeSH
• miniaturní prasata MeSH
• prasata MeSH
• protézy a implantáty MeSH
• regenerace MeSH
• testování materiálů MeSH
• tkáňové inženýrství MeSH
• tkáňové podpůrné struktury chemie   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Úvod Hluboké defekty hyalinní chrupavky kolena byly léčeny transplantací autologních chondrocytů (ACI) . Materiál a metodika 56 pacientů (31 mužů a 25 žen) bylo operováno od července 2003 do února 2007, průměrný věk 31,35 let. Operaci se podrobilo i 13 dětí (8 chlapců a 5 dívek) s průměrným věkem 15,4 let. Doba sledování 42 pacientů byla 6–40 měsíců, průměr 18,9 měsíců. Indikací k operaci byly úrazy chrupavky nebo chronické následky. Klinická vyšetření a NMR kontroly byly prováděny 2 týdny, 2 a 6 měsíců, 1, 2 a 3 roky po operaci. Kultivace chondrocytů probíhala 28 až 42 dní. Chondrograft byl implantován a fixován fibrinovým lepidlem. Výsledky Signifikantní zlepšení klinického stavu pacienta bylo zjištěno po prvních 6 měsících od operace (p < 0,001). Další zlepšení bylo prokazatelné v průběhu druhého roku po operaci (p << 0,1 podle Lysholma and Tegnera, p = 0,17 dle Meyerse). V průběhu třetího roku po výkonu se již stav pacientů nezlepšoval (p >> 0,1). Závěr Celkově bylo zaznamenáno signifikantní zlepšení klinického stavu ve většině případů. Dle NMR došlo k dobré až výborné integraci štěpu v místě původního defektu. Prognóza léčby ACI je slibná zejména u těžkých defektů. NMR je vhodná metoda k posouzení procesu hojení a integrace štěpu.

Introduction The study was focused on the evaluation of results of the full-thickness hyaline cartilage defects treated by autologous chondrocytes implantation (ACI). Material and Methods 56 patients was treated from July 2003 to February 2007, out of which there were 31 male and 25 female patients, mean age 31.35 years , including 13 children, 8 boys and 5 girls with the mean age 15.4 years. Follow-up period of 42 patients was 6 to 40 months, mean age 18.9 months. The surgical indications for the ACI were recent traumas of cartilage or its severe chronic sequelae - chondropathy, focal defects, osteoarthritis. Clinical and magnetic resonance imaging (MRI) examinations were performed before and at intervals of 2 weeks, 2, 6 and 12 months, 2 and 3 years after the surgery. The culturing period was ranging from 28 to 42 days. The transplantation followed and the chondrograft was implanted and fixed by the fibrin glue to the defect bottom. Results The significant clinical function improvement was achieved after the first 6 months, as well as after the following 6 months postoperatively (in both periods p < 0.001). Other slight improvement during the second year postoperatively was observed (p << 0.1 Lysholm and Tegner score; p = 0.17 Meyers score). During the third year there was no other significant clinical function improvement (p >> 0.1). Conclusion In comparison with the initial state the significant postoperative clinical function improvement was achieved in most of the cases. MRI evaluation shows satisfactory or excellent integration of the chondrograft into the original defect zone in all cases. Result achieved by the ACI is a very promissing option for the treatment, particulary in cases, which could be hardly treated by another surgical techniques. MRI confirmation of the surgery and its success is unavoidable when clinical improvement or ethic reasons does not allow to perform a second-look arthroscopy, eventually a control histopathological examination.

• MeSH
• autologní transplantace dějiny   metody   využití   MeSH
• chondrocyty imunologie   transplantace   MeSH
• dítě MeSH
• kolenní kloub fyziologie   patologie   MeSH
• kultivované buňky imunologie   transplantace   MeSH
• lidé středního věku MeSH
• lidé MeSH
• longitudinální studie MeSH
• mladiství MeSH
• nukleární magnetická rezonance biomolekulární diagnostické užití   metody   MeSH
• ortopedické výkony metody   využití   MeSH
• retrospektivní studie MeSH
• transplantace buněk dějiny   metody   využití   MeSH
• výsledek terapie MeSH
• Check Tag
• dítě MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH

A new composite scaffold containing type I collagen, hyaluronan, and fibrin was prepared with and without autologous chondrocytes and implanted into a rabbit femoral trochlea. The biophysical properties of the composite scaffold were similar to native cartilage. The macroscopic, histological, and immunohistochemical analysis of the regenerated tissue from cell-seeded scaffolds was performed 6 weeks after the implantation and predominantly showed formation of hyaline cartilage accompanied by production of glycosaminoglycans and type II collagen with minor fibro-cartilage production. Implanted scaffolds without cells healed predominantly as fibro-cartilage, although glycosaminoglycans and type II collagen, which form hyaline cartilage, were also observed. On the other hand, fibro-cartilage or fibrous tissue or both were only formed in the defects without scaffold. The new composite scaffold containing collagen type I, hyaluronan, and fibrin, seeded with autologous chondrocytes and implanted into rabbit femoral trochlea, was found to be highly effective in cartilage repair after only 6 weeks. The new composite scaffold can therefore enhance cartilage regeneration of osteochondral defects, by the supporting of the hyaline cartilage formation.

• MeSH
• biomechanika MeSH
• chondrocyty cytologie   MeSH
• elektronová mikroskopie MeSH
• fibrin MeSH
• kolagen typu I MeSH
• králíci MeSH
• kultivované buňky MeSH
• kyselina hyaluronová MeSH
• poranění kolena chirurgie   MeSH
• protézy a implantáty MeSH
• testování materiálů MeSH
• viabilita buněk MeSH
• zvířata MeSH
• Check Tag
• králíci MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• práce podpořená grantem MeSH

Transplantace chrupavek v terapii osteoarthrozy kolene. MRI kolenního kloubu. Hodnotící systém efektivity léčby osteoarthrozy kolene systemem OKES a MRI.; Transplantation of the cartilage in the treatment of OA of the knee. MRI of the knee joint. Evaluation system of the efficacy of OA of the knee treatment based on OKES and MRI evaluation.

• MeSH
• artróza kolenních kloubů terapie   MeSH
• chondrocyty transplantace   MeSH
• kloubní chrupavka chirurgie   transplantace   MeSH
• nukleární magnetická rezonance biomolekulární MeSH

• Konspekt
• Ortopedie. Chirurgie. Oftalmologie
• NLK Obory
• ortopedie
• revmatologie
• chirurgie
• NLK Publikační typ
• závěrečné zprávy o řešení grantu IGA MZ ČR

ECM is composed of different collagenous and non-collagenous proteins. Collagen nanofibers play a dominant role in maintaining the biological and structural integrity of various tissues and organs, including bone, skin, tendon, blood vessels, and cartilage. Artificial collagen nanofibers are increasingly significant in numerous tissue engineering applications and seem to be ideal scaffolds for cell growth and proliferation. The modern tissue engineering task is to develop three-dimensional scaffolds of appropriate biological and biomechanical properties, at the same time mimicking the natural extracellular matrix and promoting tissue regeneration. Furthermore, it should be biodegradable, bioresorbable and non-inflammatory, should provide sufficient nutrient supply and have appropriate viscoelasticity and strength. Attributed to collagen features mentioned above, collagen fibers represent an obvious appropriate material for tissue engineering scaffolds. The aim of this minireview is, besides encapsulation of the basic biochemical and biophysical properties of collagen, to summarize the most promising modern methods and technologies for production of collagen nanofibers and scaffolds for artificial tissue development.

• MeSH
• cytoskelet chemie   MeSH
• extracelulární matrix - proteiny chemie   MeSH
• extracelulární matrix chemie   MeSH
• kolagen chemie   MeSH
• lidé MeSH
• mechanický stres MeSH
• nanostruktury * MeSH
• pružnost MeSH
• testování materiálů MeSH
• tkáňové inženýrství * MeSH
• tkáňové podpůrné struktury * MeSH
• viskozita MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

The present article introduces a novel method of characterizing the macromechanical cartilage properties based on dynamic testing. The proposed approach of instrumented impact testing shows the possibility of more detailed investigation of the acting dynamic forces and corresponding deformations within the wide range of strain rates and loads, including the unloading part of stress-strain curves and hysteresis loops. The presented results of the unconfined compression testing of both the native joint cartilage tissues and potential substitute materials outlined the opportunity to measure the dissipation energy and thus to identify the initial mechanical deterioration symptoms and to introduce a better definition of material damage. Based on the analysis of measured specimen deformation, the intact and pathologically changed cartilage tissue can be distinguished and the differences revealed.

• MeSH
• biologické modely MeSH
• časové faktory MeSH
• chondrocyty fyziologie   MeSH
• kloubní chrupavka fyziologie   MeSH
• kultivované buňky MeSH
• lidé MeSH
• mechanický stres MeSH
• pevnost v tlaku MeSH
• pružnost MeSH
• selhání protézy MeSH
• testování materiálů * MeSH
• tkáňové inženýrství * MeSH
• tkáňové podpůrné struktury * MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The study is focused on the biomechanical aspects of the anterior cruciate ligament (ACL) reconstruction procedures with an emphasis on evaluating the dynamic strain of materials commonly used for this purpose. Separate and multiple, equally tensioned strands of hamstring grafts used for the reconstruction of the ACL were biomechanically tested and compared to original ACL and bone-patellar tendon-bone (BPTB) grafts, using tissue samples from cadavers. The study was focused on measuring such material properties as the strength, stiffness, maximum load, and elongation at maximum load of the original ACL, BPTB graft, and single tendon hamstring (gracilis and semitendinosus) grafts, continued by double strands and finally by four-strand graft (STG) evaluation. Fresh-frozen cadaveric knees were used, which had been clamped and tensioned equally. The measurement was performed by drop-weight testing, using a Laser Doppler Vibrometer as a basic sensor of the dynamic movements of the gripping clamps, with parallel correlation by a piezoelectric transducer. The grafts for experiments were obtained from 21-paired knees. The measurement was performed at room temperature (21 degrees C) after 24 h of thawing at 4 degrees C. All the specimens were measured for their response to the dynamic tensile load. The maximum strength values were obtained and calculated for the appropriate section area of the specimen. The tensioned strands of the original ACL showed a maximum average load of 1,246 +/- 243 N in the section area of about 30 mm(2) (max. stress 41.3 MPa); the strands of BPTB grafts showed values of 3,855 +/- 550 N in the section area of 80 mm(2) (max. stress 40.6 MPa); the gracilis tendons showed 925 +/- 127 N in the section area of 10 mm(2) (max. stress 95.1 MPa) and the semitendinosuss yielded a result of 2,050 +/- 159 N in the area of 20 mm(2) (max. stress 88.7 MPa). Of all the materials, the original ACL have the lowest strength and stiffness in respect of their biomechanical properties. BPTB grafts showed a slightly higher value of maximum stress, while both the gracilis and semitendinosus tendons showed double the value of maximum load per section area-tensile stress. Two- and four- combined hamstring strands clamped together and equally tensioned with a drop-weight had the combined tensile strength properties of the individual strands within the estimated range of measurement errors. No significant changes in maximum loads/stresses were observed under impact loading conditions. The results of this study demonstrate that equally tensioned four-strand hamstring-tendon grafts have higher initial tensile properties than those in other varieties of samples. From a biomechanical point of view, they seem to be a reasonable alternative procedure for ACL reconstruction.

• MeSH
• financování organizované MeSH
• lidé středního věku MeSH
• lidé MeSH
• ligamentum cruciatum anterius fyziologie   chirurgie   MeSH
• mechanický stres MeSH
• měniče MeSH
• mrtvola MeSH
• pevnost v tahu MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• šlachy transplantace   MeSH
• štěp kost-čéškový vaz-kost MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• senioři nad 80 let MeSH
• senioři MeSH