Transmission of Cerenkoverenkov radiation in optical fibers

Cerenkov radiation is generated as an unwanted background when optical fibers carrying signals pass through radiation fields. The angular dependence of the intensity of ? Cerenkov radiation transmitted in silica-core fibers was measured using 6 and 12 MeV electron beams from a Varian Clinic accelerator. These confirmed theoretical predictions that the angular variation of ? Cerenkov radiation transmitted along optical fibers depends only on the refractive index difference Dn between the core and the cladding, and that the peak intensity is proportional to the cube of the fiber core radius.     

Profiling of the secretome of human cancer cells: Preparation of supernatant for proteomic analysis

Secretomic analysis requires removal of serum proteins from cell‐culture media. We evaluate the proteins washed from cells prepared in bovine serum‐supplemented medium. PBS and serum‐free‐medium (SFM) were the washing solutions. A Bradford assay was used for total protein concentration and a 1D gel and LC‐MS/MS, to assign the protein to human or bovine origin. For both wash solutions, all bovine protein had been removed by the third wash, without compromising the number of living cells. Further washes reduced the number of living cells, especially when using PBS. Proteomic analysis of wash supernatant showed that SFM induced greater lysis of dead cells. Three washes were sufficient to minimize the effects on cell viability, while still removing serum proteins. Washing in SFM resulted in contamination of the wash supernatant with lysed dead cell proteins. Washed cells were incubated in SFM and exposed to ionizing radiation. Analysis of the supernatant showed an increase in human cytoplasmic, plasma membrane, and nuclear protein following irradiation. Secreted proteins were also detected, but in smaller quantities. The significance of these findings extend to in vitro studies of bystander phenomena, since the proteins of lysed dead cells may participate in driving bystander responses.