Determination of pH in Regions of the Midguts of Acaridid Mites

The pH of the guts of mites strongly affects their digestive processes. This study was carried out to determine the pH in the guts of 12 species of stored product and house dust mites. Eighteen pH indicators were chosen and offered to the mites in the feeding biotest. Based on the color changes of the indicators, the gut contents of acaridid mites were determined to be within a pH range of 4 to neutral. The gut contents showed a gradient in pH from the anterior to the posterior part. The anterior midgut (ventriculus and caeca) of most species had a pH ranging from 4.5 to 5, or slightly more alkaline for most of the species, while the middle midgut (intercolon/colon) had a pH of 5 to 6. Finally, the pH of the posterior midgut (postcolon) was between 5.5 and 7. Except for Dermatophagoides spp., no remarkable differences in the pH of the gut were observed among the tested species. Dermatophagoides spp. had a more acidic anterior midgut (a pH of 4 to 5) and colon (a pH of 5) with postcolon (a pH of below 6). The results characterizing in vivo conditions in the mite gut offer useful information to study the activity of mite digestive enzymes including their inhibitors and gut microflora

GP88 (PC-Cell Derived Growth Factor, progranulin) stimulates proliferation and confers letrozole resistance to aromatase overexpressing breast cancer cells

<p>Abstract</p> <p>Background</p> <p>Aromatase inhibitors (AI) that inhibit breast cancer cell growth by blocking estrogen synthesis have become the treatment of choice for post-menopausal women with estrogen receptor positive (ER⁺) breast cancer. However, some patients display de novo or acquired resistance to AI. Interactions between estrogen and growth factor signaling pathways have been identified in estrogen-responsive cells as one possible reason for acquisition of resistance. Our laboratory has characterized an autocrine growth factor overexpressed in invasive ductal carcinoma named PC-Cell Derived Growth Factor (GP88), also known as progranulin. In the present study, we investigated the role GP88 on the acquisition of resistance to letrozole in ER⁺breast cancer cells</p> <p>Methods</p> <p>We used two aromatase overexpressing human breast cancer cell lines MCF-7-CA cells and AC1 cells and their letrozole resistant counterparts as study models. Effect of stimulating or inhibiting GP88 expression on proliferation, anchorage-independent growth, survival and letrozole responsiveness was examined.</p> <p>Results</p> <p>GP88 induced cell proliferation and conferred letrozole resistance in a time- and dose-dependent fashion. Conversely, naturally letrozole resistant breast cancer cells displayed a 10-fold increase in GP88 expression when compared to letrozole sensitive cells. GP88 overexpression, or exogenous addition blocked the inhibitory effect of letrozole on proliferation, and stimulated survival and soft agar colony formation. In letrozole resistant cells, silencing GP88 by siRNA inhibited cell proliferation and restored their sensitivity to letrozole.</p> <p>Conclusion</p> <p>Our findings provide information on the role of an alternate growth and survival factor on the acquisition of aromatase inhibitor resistance in ER⁺breast cancer.</p

Efficient colour routing with a dispersion-controlled waveguide array

Splitting white light into its constituent spectral components has been of interest ever since Newton first discovered the phenomenon of color separation. Many devices have since been conceived to achieve efficient wavelength separation, yet a large number of applications, e. g., in display technology, still use simple color absorption or rejection filters that absorb or reflect unwanted wavelengths, thus wasting luminous energy. Here, we demonstrate a novel microsized device concept that enables efficient color routing. The device operation is based on differential material dispersion in a waveguide array, which causes different wavelength signals to couple selectively into appropriate waveguides. A theoretical power delivery of greater than 50% for a tricolor wavelength router is obtained, compared to 33% expected from geometry alone. The principle of operation is demonstrated experimentally for a dual-color light field, where we achieve a higher than 70% routing efficiency (compared to 50% from geometry), thus highlighting the feasibility of this novel and promising approach.Publisher PDFPeer reviewe