A NPxY-independent beta5 integrin activation signal regulates phagocytosis of apoptotic cells

Integrin receptors are heterodimeric transmembrane receptors with critical functions in cell adhesion and migration, cell cycle progression, differentiation, apoptosis, and phagocytosis of apoptotic cells. Integrins are activated by intracellular signaling that alter the binding affinity for extracellular ligands, so-called inside to outside signaling. A common element for integrin activation involves binding of the cytoskeletal protein talin, via its FERM domain, to a highly conserved NPxY motif in the β chain cytoplasmic tails, which is involved in long-range conformation changes to the extracellular domain that impinges on ligand affinity. When the human beta-5 (β5) integrin cDNA was expressed in αv positive, β5 and β3 negative hamster CS-1 cells, it promoted NPxY-dependent adhesion to VTN-coated surfaces, phosphorylation of FAK, and concomitantly, β5 integrin-EGFP protein was recruited into talin and paxillin-containing focal adhesions. Expression of a NPxY destabilizing β5 mutant (Y750A) abrogated adhesion and β5-Y750A-EGFP was excluded from focal adhesions at the tips of stress fibers. Surprisingly, expression of β5 Y750A integrin had a potent gain-of-function effect on apoptotic cell phagocytosis, and further, a β5-Y750A-EGFP fusion integrin readily bound MFG-E8-coated 10 μm diameter microspheres developed as apoptotic cell mimetics. The critical sequences in β5 integrin were mapped to a YEMAS motif just proximal to the NPxY motif. Our studies suggest that the phagocytic function of β5 integrin is regulated by an unconventional NPxY-talin-independent activation signal and argue for the existence of molecular switches in the β5 cytoplasmic tail for adhesion and phagocytosis.     

1-Acylthiosemicarbazides, 1,2,4-triazole-5(4H)-thiones, 1,3,4-thiadiazoles and hydrazones containing 5-methyl-2-benzoxazolinones: synthesis, analgesic-anti-inflammatory and antimicrobial activities

Acetic acid hydrazide containing 5-methyl-2-benzoxazolinone (4) was synthesized by the condensation of 2-(5-methyl-2-benzoxazolinone-3-yl)acetate with hydrazine hydrate. Thiosemicarbazide derivatives (5a-5d) were afforded by the reaction of corresponding compound 4 with substituted isothiocyanates. The cyclization of compounds 5a-5d in the presence of triethylamine resulted in the formation of compounds 6a-6d containing 1,2,4-triazole ring. On the other hand, the treatment of compounds 5a-5d with orthophosphoric acid caused the conversion of side chain of compounds 5a-5d into 1,3,4-thiadiazole ring: thus, compounds 7a-7c were obtained. The treatment of compound 4 with aromatic aldehydes resulted in the formation of arylidene hydrazides as cis-trans conformers (8a-8e). The structures of the compounds were elucidated by spectral and elemental analysis. While most compounds were exhibiting high activity in the analgesic-anti-inflammatory field, most of them were found to be inactive against bacteria and fungi.     

Prospective identification of myogenic endothelial cells in human skeletal muscle

We document anatomic, molecular and developmental relationships between endothelial and myogenic cells within human skeletal muscle. Cells coexpressing myogenic and endothelial cell markers (CD56, CD34, CD144) were identified by immunohistochemistry and flow cytometry. These myoendothelial cells regenerate myofibers in the injured skeletal muscle of severe combined immunodeficiency mice more effectively than CD56+ myogenic progenitors. They proliferate long term, retain a normal karyotype, are not tumorigenic and survive better under oxidative stress than CD56+ myogenic cells. Clonally derived myoendothelial cells differentiate into myogenic, osteogenic and chondrogenic cells in culture. Myoendothelial cells are amenable to biotechnological handling, including purification by flow cytometry and long-term expansion in vitro, and may have potential for the treatment of human muscle disease.     

Kinetic analysis of the inhibitory effect of trichloroethylene (TCE) on nitrification in cometabolic degradation

In this study, the inhibitory effect of TCE on nitrification process was investigated with an enriched nitrifier culture. TCE was found to be a competitive inhibitor of ammonia oxidation and the inhibition constant (K _I ) was determined as 666–802 μg/l. The TCE affinity for the AMO enzyme was significantly higher than ammonium. The effect of TCE on ammonium utilization was evaluated with linearized plots of Monod equation (e.g., Lineweaver–Burk, Hanes–Woolf and Eadie–Hofstee plots) and non-linear least square regression (NLSR). No significant differences were found among these data evaluation methods in terms of kinetic parameters obtained.     

Kinetic models for the dynamical behavior of polyacrylamide (PAAm)–κ-carrageenan (κC) composite gels

A fluorescence method was employed for studying the drying and swelling of PAAm–κC composite gels, which were formed from acrylamide (AAm) and N, N’- methylenebisacrylamide (BIS) with various κ–carrageenan (κC) contents by free radical crosslinking copolymerization in water. Composite gels were prepared at 80 °C with pyranine (Py) as a fluorescence probe. Scattered light, I_sc, and fluorescence emission intensities, I_em, were monitored during drying and swelling of these gels. The fluorescence intensity of pyranine increased and decreased as drying and swelling time are increased, respectively, for all gel samples. The Stern–Volmer equation combined with moving boundary and Li-Tanaka models were used to explain the behavior of I_em during drying and swelling processes respectively. It is found that the desorption coefficient D_d decreased as κC contents were increased for a given temperature during drying. However, the cooperative diffusion coefficient, D_s presented exactly the opposite case. Conventional gravimetrical and volumetric experiments were also carried out during drying and swelling of PAAm–κC composite gels. It was observed that D_d and D_s values measured with the fluorescence method were found to be much larger than they were measured with the conventional methods.     

Pesta granule trials with Aspergillus alliaceus for the biocontrol of Orobanche spp.

The pathogenic fungus Aspergillus alliaceus has been shown to have potential for the biocontrol of Orobanche spp. (broomrape), a root parasitic plant. The effectiveness of A. alliaceus in reducing Orobanche infection was analysed using pesta granules prepared with different food formulations. The results showed that pesta granules comprising of fungal mycelia/spore mixtures from liquid and solid culture, sclerotia and fungal mycelia reduced Orobanche infection to a greater extent in below ground conditions when applied early and at high doses before crop sowing. In addition, pesta granules eliminated the risk of broomrape contamination within a 0.2–0.3 cm diameter of the granules. The sclerotial pathogenicity of A. alliaceus was compared with those of other fungi reported in other studies. In addition, some morphological and histological studies on the fungal pathogenicity on broomrape plants after infection are presented. The present study reveals the potential of sclerotial A. alliaceus pesta granule applications for long-term broomrape biocontrol under field conditions.