Browsing by Subject "EXTRUSION"

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  • Wickstroem, Sara A.; Niessen, Carien M. (2018)
    Biological patterns emerge through specialization of genetically identical cells to take up distinct fates according to their position within the organism. How initial symmetry is broken to give rise to these patterns remains an intriguing open question. Several theories of patterning have been proposed, most prominently Turing's reaction-diffusion model of a slowly diffusing activator and a fast diffusing inhibitor generating periodic patterns. Although these reaction-diffusion systems can generate diverse patterns, it is becoming increasingly evident that cell shape and tension anisotropies, mediated via cell-cell and/or cell-matrix contacts, also facilitate symmetry breaking and subsequent self-organized tissue patterning. This review will highlight recent studies that implicate local changes in adhesion and/or tension as key drivers of cell rearrangements. We will also discuss recent studies on the role of cadherin and integrin adhesive receptors in mediating and responding to local tissue tension asymmetries to coordinate cell fate, position and behavior essential for tissue self-organization and maintenance.
  • Mavrovic, Martina; Uvarov, Pavel; Delpire, Eric; Vutskits, Laszlo; Kaila, Kai; Puskarjov, Martin (2020)
    KCC2, encoded in humans by the SLC12A5 gene, is a multifunctional neuron-specific protein initially identified as the chloride (Cl-) extruder critical for hyperpolarizing GABA(A) receptor currents. Independently of its canonical function as a K-Cl cotransporter, KCC2 regulates the actin cytoskeleton via molecular interactions mediated through its large intracellular C-terminal domain (CTD). Contrary to the common assumption that embryonic neocortical projection neurons express KCC2 at non-significant levels, here we show that loss of KCC2 enhances apoptosis of late-born upper-layer cortical projection neurons in the embryonic brain. In utero electroporation of plasmids encoding truncated, transport-dead KCC2 constructs retaining the CTD was as efficient as of that encoding full-length KCC2 in preventing elimination of migrating projection neurons upon conditional deletion of KCC2. This was in contrast to the effect of a full-length KCC2 construct bearing a CTD missense mutation (KCC2(R952H)), which disrupts cytoskeletal interactions and has been found in patients with neurological and psychiatric disorders, notably seizures and epilepsy. Together, our findings indicate ion transport-independent, CTD-mediated regulation of developmental apoptosis by KCC2 in migrating cortical projection neurons.
  • Semjonov, Kristian; Lust, Andres; Kogermann, Karin; Laidmäe, Ivo; Maunu, Sirkka Liisa; Hirvonen, Sami-Pekka; Yliruusi, Jouko; Nurk, Gunnar; Lust, Enn; Heinamäki, Jyrki (2018)
    The present study introduces a modified melt-electrospinning (MES) method for fabricating the melt-electrospun fibers (MSFs) of a poorly water-soluble drug and carrier polymer. The MES of poorly water-soluble model drug indomethacin (IND) and hydrophilic carrier polymer, Soluplus (R) (SOL) were prepared at a 1:3 drug-polymer weight ratio. Water was used as an external plasticizer to regulate a MES processing temperature and to improve fiber formation. The fiber size, surface morphology, physical solid state, drug-polymer (carrier) interactions, thermal and chemical stability and dissolution behavior of MSFs were investigated. Solid state nuclear magnetic resonance spectroscopy (NMR) was used to measure T1(H-1), and the domain size of IND in MSFs (25-100 nm) was calculated from these results. Solid-state and thermal analysis confirmed the presence of amorphous solid dispersions of IND and SOL. IND was found to be chemically stable during an entire MES process. Only small drug content variability of different MSF batches was detected with high performace liquid chromatography (HPLC). Given findings were verified with the liquid NMR spectroscopy. The dissolution of MSFs was significantly faster than that of physical mixtures (PMs) or pure drug. The enhanced dissolution of MSFs was caused by high surface area, amorphous state of the drug and solubilizing properties of the carrier polymer (SOL).
  • Ramos Diaz, Jose Martin; Kirjoranta, Satu; Tenitz, Seppo; Penttilä, Paavo A; Serimaa, Ritva; Lampi, Anna-Maija; Jouppila, Kirsi (2013)
    Amaranth (Amaranthus caudatus), quinoa (Chenopodium quinoa) and kañiwa (Chenopodium pallidicaule) are pseudocereals regarded as good gluten-free sources of protein and fiber. A co-rotating twin screw extruder was used to obtain corn-based extrudates containing amaranth/quinoa/kañiwa (20% of solids). Box–Behnken experimental design with three independent variables was used: water content of mass (WCM, 15–19%), screw speed (SS, 200–500 rpm) and temperature of the die (TEM, 150–170 °C). Milled and whole samples were stored in open headspace vials at 11 and 76% relative humidity (RH) for a week before being sealed and stored for 9 weeks in the dark. Hexanal content was determined by using headspace gas chromatography. Extrudates containing amaranth presented the highest sectional expansion index (SEI) (p < 0.01) while pure corn extrudates (control) presented the lowest SEI and greatest hardness (p < 0.01). SEI increased with increasing SS and decreasing WCM. In storage, whole extrudates exposed to 76% RH presented the lowest formation of hexanal. This study proved that it was possible to increase SEI by adding amaranth, quinoa and kañiwa to pure corn flour. The evaluation of lipid oxidation suggested a remarkable stability of whole extrudates after exposure to high RH.