Facebook use and negative body image among U.S. college women

Young women increasingly spend time on social media, but the relationship of this exposure to body image is still in the initial stages of exploration. In this study the authors used social comparison theory to examine the relationship between time spent on Facebook and body image. A survey of 881 U.S. college women was conducted in April–May 2013. Findings showed that 10.1% had posted about weight, body image, exercise, or dieting, and 27.4% had commented on friends’ posts or photos. More time on Facebook related to more frequent body and weight comparisons, more attention to the physical appearance of others, and more negative feelings about their bodies for all women. For women who wanted to lose weight, more time on Facebook also related to more disordered eating symptoms.     

Toll-like receptor 2 mediates microglia/brain macrophage MT1-MMP expression and glioma expansion

Background

Glioblastomas are the most aggressive primary brain tumors in humans. Microglia/brain macrophage accumulation in and around the tumor correlates with malignancy and poor clinical prognosis of these tumors. We have previously shown that microglia promote glioma expansion through upregulation of membrane type 1 matrix metalloprotease (MT1-MMP). This upregulation depends on signaling via the Toll-like receptor (TLR) adaptor molecule myeloid differentiation primary response gene 88 (MyD88).

Methods

Using in vitro, ex vivo, and in vivo techniques, we identified TLR2 as the main TLR controlling microglial MT1-MMP expression and promoting microglia-assisted glioma expansion.

Results

The implantation of mouse GL261 glioma cells into TLR2 knockout mice resulted in significantly smaller tumors, reduced MT1-MMP expression, and enhanced survival rates compared with wild-type control mice. Tumor expansion studied in organotypic brain slices depended on both parenchymal TLR2 expression and the presence of microglia. Glioma-derived soluble factors and synthetic TLR2 specific ligands induced MT1-MMP expression in microglia from wild-type mice, but no such change in MT1-MMP gene expression was observed in microglia from TLR2 knockout mice. We also found evidence that TLR1 and TLR6 cofunction with TLR2 as heterodimers in regulating MT1-MMP expression in vitro.

Conclusions

Our results thus show that activation of TLR2 along with TLRs 1 and/or 6 converts microglia into a glioma supportive phenotype.     

Thymosin β4 induces folding of the developing optic tectum in the chicken (Gallus domesticus)

Thymosin β4 (Tβ4) is a highly conserved G-actin binding polypeptide with multiple intra- and extracellular functions. While stem-cell activation as well as promotion of cell survival and migration by Tβ4 have been investigated in various in vitro and in vivo studies, there are few data on the implications of Tβ4 in brain development. In the present study we analyzed Tβ4 expression in the developing optic tectum of the chicken (Gallus domesticus) and performed in ovo retroviral transduction and plasmid electroporation for overexpression and knockdown of Tβ4. We found marked Tβ4 expression in the tectal plate and in all neuronal layers of later developmental stages, but not in the ventricular zone where neural stem cells reside and divide. Knockdown of Tβ4 inhibited growth of Tβ4-depleted hemispheres, whereas overexpression of Tβ4 led to the production of neuroepithelial folds resembling gyri and sulci, which are not normally present in avian brains. The mechanism yielding enhanced growth of Tβ4 overexpressing hemispheres involved enhanced proliferation, thus indicating an impact of Tβ4 on the neural stem cell and/or progenitor cell population. In summary, we found that due to its effects on proliferation, Tβ4 expression has a large impact on neuroepithelial and macroscopic brain development.