ABSTRACT
We demonstrate a narrow-linewidth, high side-mode suppression ratio (SMSR) semiconductor laser based on the external optical feedback injection locking technology of a femtosecond-apodized (Fs-apodized) fiber Bragg grating (FBG). A single frequency output is achieved by coupling and integrating a wide-gain quantum dot (QD) gain chip with a Fs-apodized FBG in a 1-µm band. We propose this low-cost and high-integration scheme for the preparation of a series of single-frequency seed sources in this wavelength range by characterizing the performance of 1030 nm and 1080 nm lasers. The lasers have a maximum SMSR of 66.3 dB and maximum output power of 134.6 mW. Additionally, the lasers have minimum Lorentzian linewidths that are measured to be 260.5 kHz; however, a minimum integral linewidth less than 180.4 kHz is observed by testing and analyzing the power spectra of the frequency noise values of the lasers.
ABSTRACT
To evaluate the effect of Ligustrazine on the expression of VEGF in bone marrow stromal cells (BMSCs) of radiation injured mice and to explore the effect of VEGF on the recovery of hematopoiesis and the mechanism of signal transduction, the protein expression of VEGF, focal adhesion kinase (FAK) and mitogen-activated protein kinase (MAPK) in BMSCs were assayed by Western blot, the cell cycle and apoptosis rate of BMSCs were tested by flow cytometry. The effect of Ligustrazine on the hematopoiesis was evaluated at the same time. The results showed that the protein expression of VEGF in BMSCs was decreased significantly after irradiation and increased slowly with the time. The value in Ligustrazine-treated group almost reached normal level, but it remained lower than that in control group on day 14. The changes of phosphorylated FAK and MAPK protein expression had the same tendency. After (60)Co gamma-irradiation, the BMSCs were arrested in G0-G1 phase and apoptosis rate increased; these values recovered slowly with the time and remained higher than that in normal control group on day 14. The recovery of these values in Ligustrazine-treated group was sooner than that in irradiated control group, and they almost reached to the normal levels on day 14. It is concluded that irradiation could inhibit the expression of VEGF in BMSCs and induce apoptosis. The Ligustrazine promotes the recovery of bone marrow microenvironment probably by increasing the expression of phosphorylated FAK and MAPK in BMSCs.
Subject(s)
Bone Marrow Cells/drug effects , Pyrazines/pharmacology , Radiation Injuries, Experimental/drug therapy , Radiation-Protective Agents/pharmacology , Vascular Endothelial Growth Factor A/analysis , Animals , Apoptosis/drug effects , Bone Marrow Cells/metabolism , Cell Cycle/drug effects , Cell Division/drug effects , Focal Adhesion Kinase 1 , Focal Adhesion Protein-Tyrosine Kinases , Mice , Protein-Tyrosine Kinases/analysis , Radiation Injuries, Experimental/metabolism , Stromal Cells/drug effects , Stromal Cells/metabolismABSTRACT
To explore the hematopoiesis inhibition mechanisms of interferon-gamma (IFN-gamma), the effects of IFN-gamma on the expression of the cyclin D in the umbilical cord blood hematopoietic stem/progenitor cells were observed. In the experiments the CD34(+) cells were isolated from the cord blood with MIDI-MACS system; semi-solid methylcellulose culture technique was used to measure the formation of CFU-GM; the expression levels of cyclin D isoforms were assayed by semi-quantitative RT-PCR, after the hematopoietic stem/progenitor cells were incubated with IFN-gamma. The results indicated that IFN-gamma could inhibit the formation of CFU-GM and down-regulate the expression of cyclin D2 and cyclin D3 at the mRNA level. It is concluded that the IFN-gamma could inhibit the proliferation of hematopoietic stem cells and down-regulate the expression of cyclin D, that may be one mechanism underlying the hematopoietic inhibition of IFN-gamma.