Multilayer Dotaz Zobrazit nápovědu
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.
The modification of biomaterial surfaces has become increasingly relevant in the context of ongoing advancements in tissue engineering applications and the development of tissue-mimicking polymer materials. In this study, we investigated the layer-by-layer (LbL) deposition of polyelectrolyte multilayer protein reservoirs consisting of poly-l-lysine (PLL) and hyaluronic acid (HA) on the hydrophobic surface of poly(glycerol sebacate) (PGS) elastomer. Using the methods of isothermal titration calorimetry and surface plasmon resonance, we systematically investigated the interactions between the polyelectrolytes and evaluated the deposition process in real time, providing insight into the phenomena associated with film assembly. PLL/HA LbL films deposited on PGS showed an exceptional ability to incorporate bone morphogenetic protein-2 (BMP-2) compared to other growth factors tested, thus highlighting the potential of PLL/HA LbL films for osteoregenerative applications. The concentration of HA solution used for film assembly did not affect the thickness and topography of the (PLL/HA)10 films, but had a notable impact on the hydrophilicity of the PGS surface and the BMP-2 release kinetics. The release kinetics were successfully described using the Weibull model and hyperbolic tangent function, underscoring the potential of these less frequently used models to compare the protein release from LbL protein reservoirs.
Local chemotherapy using polymer drug delivery systems has the potential to treat some cancers, including intraocular retinoblastoma, which is difficult to treat with systemically delivered drugs. Well-designed carriers can provide the required drug concentration at the target site over a prolonged time, reduce the overall drug dose needed, and suppress severe side effects. Herein, nanofibrous carriers of the anticancer agent topotecan (TPT) with a multilayered structure composed of a TPT-loaded inner layer of poly(vinyl alcohol) (PVA) and outer covering layers of polyurethane (PUR) are proposed. Scanning electron microscopy showed homogeneous incorporation of TPT into the PVA nanofibers. HPLC-FLD proved the good loading efficiency of TPT (≥85%) with a content of the pharmacologically active lactone TPT of more than 97%. In vitro release experiments demonstrated that the PUR cover layers effectively reduced the initial burst release of hydrophilic TPT. In a 3-round experiment with human retinoblastoma cells (Y-79), TPT showed prolonged release from the sandwich-structured nanofibers compared with that from a PVA monolayer, with significantly enhanced cytotoxic effects as a result of an increase in the PUR layer thickness. The presented PUR-PVA/TPT-PUR nanofibers appear to be promising carriers of active TPT lactone that could be useful for local cancer therapy.
- Publikační typ
- časopisecké články MeSH
Myelin is a multilayered membrane that tightly wraps neuronal axons, enabling efficient, high-speed signal propagation. The axon and myelin sheath form tight contacts, mediated by specific plasma membrane proteins and lipids, and disruption of these contacts causes devastating demyelinating diseases. Using two cell-based models of demyelinating sphingolipidoses, we demonstrate that altered lipid metabolism changes the abundance of specific plasma membrane proteins. These altered membrane proteins have known roles in cell adhesion and signaling, with several implicated in neurological diseases. The cell surface abundance of the adhesion molecule neurofascin (NFASC), a protein critical for the maintenance of myelin-axon contacts, changes following disruption to sphingolipid metabolism. This provides a direct molecular link between altered lipid abundance and myelin stability. We show that the NFASC isoform NF155, but not NF186, interacts directly and specifically with the sphingolipid sulfatide via multiple binding sites and that this interaction requires the full-length extracellular domain of NF155. We demonstrate that NF155 adopts an S-shaped conformation and preferentially binds sulfatide-containing membranes in cis, with important implications for protein arrangement in the tight axon-myelin space. Our work links glycosphingolipid imbalances to disturbance of membrane protein abundance and demonstrates how this may be driven by direct protein-lipid interactions, providing a mechanistic framework to understand the pathogenesis of galactosphingolipidoses.
- MeSH
- demyelinizační nemoci * patologie MeSH
- glykosfingolipidy metabolismus MeSH
- lidé MeSH
- molekuly buněčné adheze metabolismus MeSH
- myelinová pochva metabolismus MeSH
- neurotrofní faktory metabolismus MeSH
- sulfoglykosfingolipidy * MeSH
- transportní proteiny metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The direct tailoring of the size, composition, or number of layers belongs to the advantages of 3D printing employment in producing orodispersible films (ODFs) compared to the frequently utilized solvent casting method. This study aimed to produce porous ODFs as a substrate for medicated ink deposited by a 2D printer. The innovative semi-solid extrusion 3D printing method was employed to produce multilayered ODFs, where the bottom layer assures the mechanical properties. In contrast, the top layer provides a porous structure for ink entrapment. Hydroxypropyl methylcellulose and polyvinyl alcohol were utilized as film-forming polymers, glycerol as a plasticizer, and sodium starch glycolate as a disintegrant in the bottom matrix. Several porogen agents (Aeroperl® 300, Fujisil®, Syloid® 244 FP, Syloid® XDP 3050, Neusilin® S2, Neusilin® US2, and Neusilin® UFL2) acted as porosity enhancers in the two types of top layer. ODFs with satisfactory disintegration time were prepared. The correlation between the porogen content and the mechanical properties was proved. A porous ODF structure was detected in most samples and linked to the porogen content. SSE 3D printing represents a promising preparation method for the production of porous ODFs as substrates for subsequent drug deposition by 2D printing, avoiding the difficulties arising in casting or printing medicated ODFs directly.
- Publikační typ
- časopisecké články MeSH
The scarcity of high-quality annotations in many application scenarios has recently led to an increasing interest in devising learning techniques that combine unlabeled data with labeled data in a network. In this work, we focus on the label propagation problem in multilayer networks. Our approach is inspired by the heat diffusion model, which shows usefulness in machine learning problems such as classification and dimensionality reduction. We propose a novel boundary-based heat diffusion algorithm that guarantees a closed-form solution with an efficient implementation. We experimentally validated our method on synthetic networks and five real-world multilayer network datasets representing scientific coauthorship, spreading drug adoption among physicians, two bibliographic networks, and a movie network. The results demonstrate the benefits of the proposed algorithm, where our boundary-based heat diffusion dominates the performance of the state-of-the-art methods.
- MeSH
- algoritmy MeSH
- řízené strojové učení * MeSH
- strojové učení MeSH
- vysoká teplota * MeSH
- Publikační typ
- časopisecké články MeSH
Generation of functional gametes is accomplished through a multilayered and finely orchestrated succession of events during meiotic progression. In the Caenorhabditis elegans germline, the HORMA-domain-containing protein HTP-3 plays pivotal roles for the establishment of chromosome axes and the efficient induction of programmed DNA double-strand breaks, both of which are crucial for crossover formation. Double-strand breaks allow for accurate chromosome segregation during the first meiotic division and therefore are an essential requirement for the production of healthy gametes. Phosphorylation-dependent regulation of HORMAD protein plays important roles in controlling meiotic chromosome behavior. Here, we document a phospho-site in HTP-3 at Serine 285 that is constitutively phosphorylated during meiotic prophase I. pHTP-3S285 localization overlaps with panHTP-3 except in nuclei undergoing physiological apoptosis, in which pHTP-3 is absent. Surprisingly, we observed that phosphorylation of HTP-3 at S285 is independent of the canonical kinases that control meiotic progression in nematodes. During meiosis, the htp-3(S285A) mutant displays accelerated RAD-51 turnover, but no other meiotic abnormalities. Altogether, these data indicate that the Ser285 phosphorylation is independent of canonical meiotic protein kinases and does not regulate HTP-3-dependent meiotic processes. We propose a model wherein phosphorylation of HTP-3 occurs through noncanonical or redundant meiotic kinases and/or is likely redundant with additional phospho-sites for function in vivo.
- MeSH
- Caenorhabditis elegans genetika metabolismus MeSH
- fosforylace MeSH
- meióza * MeSH
- proteiny buněčného cyklu genetika MeSH
- proteiny Caenorhabditis elegans * metabolismus MeSH
- segregace chromozomů MeSH
- serin metabolismus MeSH
- synaptonemální komplex metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The myelin sheath is an essential, multilayered membrane structure that insulates axons, enabling the rapid transmission of nerve impulses. The tetraspan myelin proteolipid protein (PLP) is the most abundant protein of compact myelin in the central nervous system (CNS). The integral membrane protein PLP adheres myelin membranes together and enhances the compaction of myelin, having a fundamental role in myelin stability and axonal support. PLP is linked to severe CNS neuropathies, including inherited Pelizaeus-Merzbacher disease and spastic paraplegia type 2, as well as multiple sclerosis. Nevertheless, the structure, lipid interaction properties, and membrane organization mechanisms of PLP have remained unidentified. We expressed, purified, and structurally characterized human PLP and its shorter isoform DM20. Synchrotron radiation circular dichroism spectroscopy and small-angle X-ray and neutron scattering revealed a dimeric, α-helical conformation for both PLP and DM20 in detergent complexes, and pinpoint structural variations between the isoforms and their influence on protein function. In phosphatidylcholine membranes, reconstituted PLP and DM20 spontaneously induced formation of multilamellar myelin-like membrane assemblies. Cholesterol and sphingomyelin enhanced the membrane organization but were not crucial for membrane stacking. Electron cryomicroscopy, atomic force microscopy, and X-ray diffraction experiments for membrane-embedded PLP/DM20 illustrated effective membrane stacking and ordered organization of membrane assemblies with a repeat distance in line with CNS myelin. Our results shed light on the 3D structure of myelin PLP and DM20, their structure-function differences, as well as fundamental protein-lipid interplay in CNS compact myelin.
- MeSH
- axony metabolismus MeSH
- centrální nervový systém metabolismus MeSH
- lidé MeSH
- lipidové dvojvrstvy * metabolismus MeSH
- myelinová pochva metabolismus MeSH
- myelinový proteolipidový protein * metabolismus MeSH
- protein - isoformy metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Apples are known to be a rich source of phenolic compounds, however detailed studies about their content in the individual parts of apple trees are reported rarely. For this purpose, we tested various stationary phases for the determination of phenolic compounds in leaves, bark, and buds. Phloridzin, phloretin, chlorogenic acid, rutin, and quercitrin were analyzed with high performance liquid chromatography coupled with diode array detection. A YMC Triart C18-ExRS 150 × 4.6 mm, 5 μm particle size analytical column with multilayered particle technology was used. The separation was performed with a mobile phase that consisted of acetonitrile and 0.1% phosphoric acid, according to the gradient program, at a flow rate of 1 mL/min for 12.50 min. The concentration of phenolic compounds from 13 cultivars was in the range of 64.89-106.01 mg/g of dry weight (DW) in leaves, 70.81-113.18 mg/g DW in bark, and 100.68-139.61 mg/g DW in buds. Phloridzin was a major compound. The total antioxidant activity was measured using flow analysis and the correlation with the total amount of phenolic compounds was found. This finding can lead to the re-use of apple tree material to isolate substances that can be utilized in the food, pharmaceutical, or cosmetics industries.
- Publikační typ
- časopisecké články MeSH
Most of salivary gland neoplasms (benign and malignant) are characterized by recurrent gene fusions. Pleomorphic adenoma (PA), the most frequent salivary gland tumor, is driven by chromosomal rearrangements involving PLAG1 mapped to 8q12 and HMGA2 mapped to 12q13-15 in most cases. Multiple fusion partners have been identified including CTNNB1, FGFR1, LIFR, CHCHD7 and TCEA for PLAG1 fusions and NFIB, WIF1 and FHIT for HMGA2 fusions. To date, no data exist on the morphology of the few reported HMGA2-WIF1-rearranged PAs. We present 28 major salivary gland adenomas displaying distinctive trabecular and canalicular morphology associated with recurrent genotype. Patients were 15 females and 13 males aged 43 to 87 (median: 65). All tumors originated from the parotid. Their size range was 1 to 4 cm (mean: 2.3). Histologically, all tumors showed elongated or columnar cells arranged into bilayered to multilayered communicating and branching strands and trabeculae in a manner similar to canalicular adenoma of minor salivary glands or trabecular myoepithelioma with variable solid confluent intercalated duct-like areas. Fifteen tumors were exclusively canalicular/trabecular while 13 had intermingled or well-demarcated conventional (chondromyxoid) PA component comprising 5 to >50% of the tumor. The monomorphic areas expressed uniformly CK7 (28/28), vimentin (21/21), S100 (24/24), SOX10 (16/17) and variably p63 (8/21) and mammaglobin (6/16) but were negative with p40 (0/24), smooth muscle actin (0/24) and MUC4 (0/16). Targeted RNA sequencing revealed HMGA2 fusions in 14/16 (87%) assessable cases. Fusion partner was WIF1 (12), RPSAP52 (1) and HELB (1). Separate testing of the 2 components in 1 hybrid tumor showed same HMGA2/WIF1 fusion. HMGA2 immunohistochemistry was homogeneously positive in all cases including the 2 fusion-negative cases. A control cohort of 12 genuine canalicular adenomas revealed no HMGA2 fusions (0/4) and lacked HMGA2 immunoreactivity (0/12). This study highlights a distinctive variant in the spectrum of PA characterized by prominent trabecular and canalicular adenoma-like morphology. Our data confirm that canalicular adenomas in major salivary glands (either monomorphic or part of hybrid tumors) are distinct from canalicular adenoma of minor salivary glands. Their uniform genotype irrespective of presence or absence of a conventional PA component argues for classifying those tumors lacking a conventional PA component as "monomorphic variants of PA" rather than canalicular/basal cell adenomas, intercalated duct adenoma, trabecular myoepithelioma or true hybrid tumors.
- MeSH
- adaptorové proteiny signální transdukční genetika MeSH
- dospělí MeSH
- fúze genů * MeSH
- genová přestavba * MeSH
- lidé středního věku MeSH
- lidé MeSH
- nádorové biomarkery analýza genetika MeSH
- nádory slinných žláz chemie genetika patologie MeSH
- pleomorfní adenom chemie genetika patologie MeSH
- protein HMGA2 genetika MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
