Pulmonary artery banding is a surgical procedure performed when there is a shunt between the left and right ventricle. Its aim is to constrict the lumen of the pulmonary artery by using a band to reduce blood flow to the lungs. In this study, we report the results of investigating the mechanical properties of a composite composed of poly(L-lactide-co-ε-caprolactone) layers and a collagen matrix (PLCL-COLL). PLCL layers were obtained by electrospinning, impregnated with collagen solution, and finally cross-linked to increase the stiffness of the material. Bands of PLCL-COLL were implanted into a rat peritoneum and explanted after 1, 3, and 6 months in vivo. The mechanical properties of the material before and after implantation were determined using uniaxial tensile tests. The same was done with samples of strips prepared from GORE-TEX material. By comparing the results of tensile tests before implantation and after explantation, it was found that PLCL-COLL degrades in the rat's body and that it exhibits a mechanical response showing of elastic modulus values that correspond well to arterial biomechanics (elastic modulus measured in the initial linear region of the deformation was found to be: 4.14 MPa ± 1.11 MPa, 2.34 MPa ± 1.02 MPa, 1.11 MPa ± 0.77 MPa, and 0.88 MPa ± 0.60 MPa before implantation, and 1, 3, and 6 months after implantation respectively). Similar to the elastic modulus, the strength of the PLCL-COLL composite decreased during in vivo exposure (1.32 ± 0.32 MPa, 0.60 ± 0.26 MPa, 0.44 ± 0.11 MPa, and 0.46 ± 0.28 MPa before implantation, and 1, 3, and 6 months after implantation respectively). In our experiments, PLCL-COLL material was always more compliant than GORE-TEX (elastic modulus 34.7 MPa ± 2.06 MPa before implantation, and 9.35 MPa ± 6.80 MPa after implantation). The results suggest that PLCL-COLL could be a suitable candidate for the development of artery banding tapes, and also for further use in cardiovascular surgery.

• MeSH
• arteria pulmonalis * chirurgie   MeSH
• biokompatibilní materiály chemie   MeSH
• biomechanika MeSH
• kolagen * chemie   metabolismus   MeSH
• krysa rodu rattus MeSH
• mechanické jevy * MeSH
• peritoneum * chirurgie   MeSH
• pevnost v tahu MeSH
• polyestery * chemie   metabolismus   MeSH
• testování materiálů MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Previously, a new biodegradable poly(ester urethane urea) was synthesized based on polycaprolactone-diol and fish gelatin (PU-Gel). In this work, the potential of this new material for neural tissue engineering is evaluated. Membranes with randomly oriented fibers and with aligned fibers are produced using electrospinning and characterized regarding their mechanical behavior under both dry and wet conditions. Wet samples exhibit a lower Young's modulus than dry ones and aligned membranes are stiffer and more brittle than those randomly oriented. Cyclic tensile tests are conducted and high values for recovery ratio and resilience are obtained. Both membranes exhibited a hydrophobic surface, measured by the water contact angle (WCA). Human mesenchymal stem cells from umbilical cord tissue (UC-MSCs) and human neural stem cells (NSCs) are seeded on both types of membranes, which support their adhesion and proliferation. Cells stained for the cytoskeleton and nucleus in membranes with aligned fibers display an elongated morphology following the alignment direction. As the culture time increased, higher cell viability is obtained on randomfibers for UC-MSCs while no differences are observed for NSCs. The membranes support neuronal differentiation of NSCs, as evidenced by markers for a neuronal filament protein (NF70) and for a microtubule-associated protein (MAP2).

• MeSH
• biokompatibilní materiály chemie   farmakologie   MeSH
• buněčná adheze účinky léků   MeSH
• buněčná diferenciace účinky léků   MeSH
• kultivované buňky MeSH
• lidé MeSH
• mezenchymální kmenové buňky * cytologie   účinky léků   metabolismus   MeSH
• nervové kmenové buňky * cytologie   účinky léků   metabolismus   MeSH
• pevnost v tahu MeSH
• polyestery * chemie   farmakologie   MeSH
• polyurethany * chemie   farmakologie   MeSH
• proliferace buněk účinky léků   MeSH
• testování materiálů MeSH
• tkáňové inženýrství * metody   MeSH
• tkáňové podpůrné struktury chemie   MeSH
• viabilita buněk účinky léků   MeSH
• želatina * chemie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

Material properties of soft-tissue samples are often derived through uniaxial tensile testing. For engineering materials, testing parameters (e.g., sample geometries and clamping conditions) are described by international standards; for biological tissues, such standards do not exist. To investigate what testing parameters have been reported for tensile testing of human soft-tissue samples, a systematic review of the literature was performed using PRISMA guidelines. Soft tissues are described as anisotropic and/or hyperelastic. Thus, we explored how the retrieved parameters compared against standards for engineering materials of similar characteristics. All research articles published in English, with an Abstract, and before 1 January 2023 were retrieved from databases of PubMed, Web of Science, and BASE. After screening of articles based on search terms and exclusion criteria, a total 1,096 articles were assessed for eligibility, from which 361 studies were retrieved and included in this review. We found that a non-tapered shape is most common (209 of 361), followed by a tapered sample shape (92 of 361). However, clamping conditions varied and were underreported (156 of 361). As a preliminary attempt to explore how the retrieved parameters might influence the stress distribution under tensile loading, a pilot study was performed using finite element analysis (FEA) and constitutive modeling for a clamped sample of little or no fiber dispersion. The preliminary FE simulation results might suggest the hypothesis that different sample geometries could have a profound influence on the stress-distribution under tensile loading. However, no conclusions can be drawn from these simulations, and future studies should involve exploring different sample geometries under different computational models and sample parameters (such as fiber dispersion and clamping effects). Taken together, reporting and choice of testing parameters remain as challenges, and as such, recommendations towards standard reporting of uniaxial tensile testing parameters for human soft tissues are proposed.

• Publikační typ
• systematický přehled MeSH

The application of microfluidic devices as next-generation cell and tissue culture systems has increased impressively in the last decades. With that, a plethora of materials as well as fabrication methods for these devices have emerged. Here, we describe the rapid prototyping of microfluidic devices, using micromilling and vapour-assisted thermal bonding of polymethyl methacrylate (PMMA), to create a spheroid-on-a-chip culture system. Surface roughness of the micromilled structures was assessed using scanning electron microscopy (SEM) and atomic force microscopy (AFM), showing that the fabrication procedure can impact the surface quality of micromilled substrates with milling tracks that can be readily observed in micromilled channels. A roughness of approximately 153 nm was created. Chloroform vapour-assisted bonding was used for simultaneous surface smoothing and bonding. A 30-s treatment with chloroform-vapour was able to reduce the surface roughness and smooth it to approximately 39 nm roughness. Subsequent bonding of multilayer PMMA-based microfluidic chips created a durable assembly, as shown by tensile testing. MDA-MB-231 breast cancer cells were cultured as multicellular tumour spheroids in the device and their characteristics evaluated using immunofluorescence staining. Spheroids could be successfully maintained for at least three weeks. They consisted of a characteristic hypoxic core, along with expression of the quiescence marker, p27kip1. This core was surrounded by a ring of Ki67-positive, proliferative cells. Overall, the method described represents a versatile approach to generate microfluidic devices compatible with biological applications.

• MeSH
• chloroform MeSH
• laboratoř na čipu MeSH
• mikrofluidika * metody   MeSH
• mikrofluidní analytické techniky * MeSH
• polymethylmethakrylát chemie   MeSH
• Publikační typ
• časopisecké články MeSH

OBJECTIVES: This study evaluated how deproteinization using sodium hypochlorite (6% NaOCl) or hypochlorous acid (50 ppm HOCl) with or without the subsequent use of an arylsulfinate salt-containing agent (Clearfil DC Activator; DCA; Kuraray Noritake Dental) affects the micro-tensile bond strength (μTBS) and formation of an acid-base resistant zone (ABRZ) of a two-step self-etch adhesive on eroded dentin. METHODS: Coronal dentin surfaces of sound human molars were exposed to 48 cycles of demineralization (1% citric acid; 5 minutes) and remineralization (buffer solution with pH=6.4; 3.5 hours). They were then assigned to experimental groups according to the pretreatment used: none (negative control), NaOCl, NaOCl+DCA, HOCl, and HOCl+DCA. Sound dentin surfaces with no pretreatment were used as a positive control. The dentin surfaces were bonded with Clearfil SE Bond 2 (Kuraray Noritake Dental), and μTBS was measured either after 24 hours or 20,000 thermal cycles (TC). The μTBS data were statistically analyzed using a mixed-model analysis of variance (ANOVA) and t-tests with Bonferroni correction. Failure mode was determined with scanning electron microscopy (SEM), which was also used for the observation of ABRZ. RESULTS: Among experimental groups, there was no significant difference between the negative control, HOCl, and HOCl+DCA after 24 hours, but the HOCl-pretreated groups exhibited significantly higher μTBS than the negative control after TC (p<0.01). Pretreatment with NaOCl and NaOCl+DCA resulted in significantly higher μTBS (p<0.001), but the highest μTBS was measured on sound dentin (p<0.001). TC decreased μTBS significantly in all groups (p<0.001) except for sound dentin and NaOCl+DCA (p>0.05). Adhesive failures prevailed in eroded groups, whereas cohesive failures were predominant on sound dentin. ABRZ was recognized in all groups but marked morphological differences were observed. CONCLUSIONS: The combined use of 6% NaOCl and the arylsulfinate salt-containing agent partially reversed the compromised bonding performance on eroded dentin, while the effect of 50 ppm HOCl was negligible.

• MeSH
• dentin MeSH
• dentinová adheziva farmakologie   chemie   MeSH
• lidé MeSH
• pevnost v tahu MeSH
• pryskyřičné cementy farmakologie   chemie   MeSH
• testování materiálů MeSH
• vazba zubní * metody   MeSH
• zubní cementy * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

INTRODUCTION: The aim of this work was the evaluation of surface modification in surgery of normally used hernia implants and thus improving their antimicrobial properties. The modification consisted of applying hybrid nanolayers with immobilized antiseptic substances (metal cations of Ag, Cu, and Zn) by sol-gel method which ensures prolonged effect of these substances and thus enables a greater resistance of the implant towards infection. In this work, attention is drawn to the issue of applying hybrid nanolayers, activation of mesh surfaces by physical plasma modification or ultraviolet C (UV C) radiation, and influence of these modifications on the mechanical properties of the final meshes. Next work will continue concentrating on the issue of antimicrobial efficacy and eventual toxicity of the prepared layers. MATERIALS AND METHODS: Present-day materials of the most commonly used types of implants for reconstruction of the abdominal wall in surgery (polypropylene, polyester, polyvinylidenefluoride) were tested. Optimum conditions of application of nanolayers by sol-gel method and their thermal stabilization were examined first. Surface modification was verified by scanning electron microscope. The surface of implants was first activated for better adhesion by plasma treatment or UV radiation after preliminary tests. Maximum strength and ductility after activation and hybrid nanolayer modification were objectively measured on a universal Testometric tensile testing machine. RESULTS: The results of surface activation of the meshes (by both plasma treatment or UV C radiation) provided similar and satisfactory results, and particular conditions differed based on the type of material of the mesh. Usage of antimicrobial sol AD30 diluted by isopropyl alcohol in 1:1 proportion appear to be optimal. All tested cases of meshes activated by plasma treatment or UV C radiation and with applied nanolayer concluded in a slight reduction of mechanical properties in modified meshes in comparison with the original ones. However, a slight reduction of test values was not of clinical importance. CONCLUSION: It was verified that surface modification of implants by sol-gel method is effective and technically possible, providing hopeful results.

• MeSH
• antiinfekční látky * farmakologie   MeSH
• chirurgické síťky MeSH
• pevnost v tahu MeSH
• protézy a implantáty MeSH
• testování materiálů MeSH
• Publikační typ
• časopisecké články MeSH

Hydrogel based matrices and titanium dioxide (TiO2) nanoparticles (NPs) are well established materials in bone tissue engineering. Nevertheless, there is still a challenge to design appropriate composites with enhanced mechanical properties and improved cell growth. Progressing in this direction, we synthesized nanocomposite hydrogels by impregnating TiO2 NPs in a chitosan and cellulose-based hydrogel matrix containing polyvinyl alcohol (PVA), to enhance the mechanical stability and swelling capacity. Although, TiO2 has been incorporated into single and double component matrix systems, it has rarely been combined with a tri-component hydrogel matrix system. The doping of NPs was confirmed by Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy and small- and wide-angle X-ray scattering. Our results showed that incorporation of TiO2 NPs improved the tensile properties of the hydrogels significantly. Furthermore, we performed biological evaluation of scaffolds, swelling degree, bioactivity assessment, and hemolytic tests to prove that all types of hydrogels were safe for use in the human body. The culturing of human osteoblast-like cells MG-63 on hydrogels showed better adhesion of cells in the presence of TiO2 and showed increasing proliferation with increasing amount of TiO2. Our results showed that the sample with the highest TiO2 concentration, CS/MC/PVA/TiO2 (1 %) had the best biological properties.

• MeSH
• celulosa farmakologie   MeSH
• chitosan * farmakologie   chemie   MeSH
• hydrogely farmakologie   chemie   MeSH
• lidé MeSH
• nanočástice * chemie   MeSH
• polyvinylalkohol chemie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

Polypropylene (PP) belongs among the most important commodity plastics due to its widespread application. The color of the PP products can be achieved by the addition of pigments, which can dramatically affect its material characteristics. To maintain product consistency (dimensional, mechanical, and optical), knowledge of these implications is of great importance. This study investigates the effect of transparent/opaque green masterbatches (MBs) and their concentration on the physico-mechanical and optical properties of PP produced by injection molding. The results showed that selected pigments had different nucleating abilities, affecting the dimensional stability and crystallinity of the product. The rheological properties of pigmented PP melts were affected as well. Mechanical testing showed that the presence of both pigments increased the tensile strength and Young's modulus, while the elongation at break was significantly increased only for the opaque MB. The impact toughness of colored PP with both MBs remained similar to that of neat PP. The optical properties were well controlled by the dosing of MBs, and were further related to the RAL color standards, as demonstrated by CIE color space analysis. Finally, the selection of appropriate pigments for PP should be considered, especially in areas where dimensional and color stability, as well as product safety, are highly important.

• MeSH
• houby MeSH
• modul pružnosti MeSH
• plastické hmoty * MeSH
• polypropyleny * MeSH
• pomocné látky MeSH
• Publikační typ
• časopisecké články MeSH

An important feature of orodispersible tablets (ODTs) is the convenient administration of the drugs, in some cases, faster onset of action, stability maintenance, and dose precision. This work focused on the preparation of ODTs containing mannitol-based co-processed excipients Prosolv® ODT G2, Ludiflash® and Parteck® ODT in combination with tramadol, captopril, and domperidone by direct compression. Prosolv® ODT G2 showed high energy of plastic deformation due to the content of microcrystalline cellulose. Parteck® ODT provided compact tablets due to the content of granulated mannitol. All drugs decreased tensile strength, increased friability, prolonged disintegration time, and decreased the porosity of tablets. Tablets containing Prosolv® ODT G2 with captopril, domperidone, and tramadol; and Parteck® ODT with domperidone met the requirements for ODTs production, i.e., friability ≤ 1% and disintegration time ≤ 180 s, fast wetting time, high water absorption ratio, and adequate tensile strength. The disintegration time was tested using both the pharmacopeial method and the BJKSN-13 apparatus. The results indicate the significant difference between these methods, with the disintegration time being longer when tested with the BJKSN-13 instrument.

• MeSH
• aplikace orální MeSH
• domperidon MeSH
• kaptopril MeSH
• mannitol chemie   MeSH
• pomocné látky * chemie   MeSH
• příprava léků metody   MeSH
• rozpustnost MeSH
• tablety chemie   MeSH
• tramadol * MeSH
• Publikační typ
• časopisecké články MeSH

PURPOSE OF THE STUDY We aimed to evaluate the biomechanical properties of quadriceps tendon graft with a bone plug ending (QTBP) and a quadriceps graft with a tendinous ending(QTT) fixed on the femoral side with different fixation devices. MATERIAL AND METHODS Twenty-five paired 2-year-old calf QTs and 25 paired 2-year-old sheep femurs were used for this study. 90x8 mm central part of the quadriceps tendons with or without a bone plug was harvested. 8×25 mm tunnel was placed in lateral condyles. The QTT was fixed with four different fixation devices, including the adjustable suspensory system (QTT-ASS, group 1), biodegradable interference screws (QTT-BIS, group 2), titanium interference screws (QTT-TIS, group 3), and an adjustable suspensory system + biodegradable interference screws (QTT-(ASS+BIS), group 4); QTBP was fixed with titanium interference screws (QTBP-TIS, group 5). All groups were tested in a servohydraulic materials testing machine. Stiffness(N/mm), slippage of the tendon(mm), and the ultimate tensile load-bearing ability(N) of the groups were tested. The Kruskal-Wallis H test was used with the Monte Carlo simulation technique to compare the nonparametric variables of stiffness, slippage, and ultimate tensile load. Dunn's test was used for the post hoc analyses. RESULTS Group 3 had the stiffest fixation (median 45.09 N/mm). The amount of slippage was highest in group 1(median 6.41mm). Group 1 was the most resistant group against a tensile load during the load-to-failure test(464 N). Fixing the QTT with the ASS and BIS in group 4 increased both stiffness and ultimate tensile load strength. There was no significant difference between the QTBP and QTT fixed with titanium screws. Fixing QTT with titanium screws was significantly superior to fixation with BIS(p < 0.05). CONCLUSIONS This study demonstrates that QTBP fixation with TIS have no advantage over QTT fixation with TIS on the femoral side. Although the QTT group fixed with ASS was the most resistant group against tensile forces during load-to-failure test, amount of slippage was highest for this group as well. Thus, if an ASS is to be used, a strong tension force must be applied prior to tibial side fixation to prevent further slippage of the graft in the tunnel. Key words: anterior cruciate ligament, quadriceps tendon graft, femoral side, fixation, biomechanical properties.

• MeSH
• biomechanika MeSH
• Equidae MeSH
• kostní šrouby * MeSH
• ovce MeSH
• šlachy transplantace   MeSH
• titan * MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH