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Macrophages are considered as a source of important mediators to release growth factors that stimulate fibroblast proliferation during wound repair. The goal of the study was to evaluate the potential of stimulation on fibroblast proliferation cultured in the supernatant from low level light irradiated U-937 cells, a macrophage-like lymophoma cell line. The U-937 supernatant was removed twenty-four hours after Light Emitting Diodes (LEDs) exposure and was added to human foreskin fibroblast culture media. The proliferation of fibroblasts was measured by trypan blue stain. The concentration of total collagen and non-collagenous protein of fibroblasts was estimated by Fast green-Sirius red staining assay. The result showed that LEDs irradiation under the setting of 630 nm, 15 mw/cm2, and 4J/cm2 might encourage U-937 cells to release growth factors to stimulate fibroblast proliferation compared to the control group. The rate of fibroblast proliferation increased 1.1 fold compared to the control group which received supernatant from U-937 culture without light irradiation. The ratio of the concentration of collagen to non-collagenous protein of fibroblasts increased from 38.46±0.25 to 42.50±0.92 µg/mg (p<0.01) at forty-eight hours after fibroblast culture media replaced by light irradiated U-937 culture supernatant. The result suggests that in vitro irradiation of U-937 cells by LEDs at specific parameter could modify their ability, therefore, affect the proliferation of fibroblasts. [ABSTRACT FROM AUTHOR]

Light scattering is a non-contact technique which can be used for characterizing the topography of smooth reflecting surfaces. A technique which incorporates an integrated laser scattering model for surface roughness measurement of a semi-conductor wafer has been developed. The technique employs a He-Ne laser and incorporates various optical components (Fig. 1) to record surface roughness in the nanometer range with a high degree of accuracy. Theory of the technique and the experimental program are described. The results obtained show excellent agreement with method using the atomic force microscope with only minor discrepancy. This is a significant improvement over the conventional stylus methods, In addition, unlike previous laser scattering method which uses a spherical arrangement to record diffused light, the proposed technique detects reflected light normal to the test surface and hence resulting in a simpler and more stable optical arrangement. Using the proposed optical arrangement, accurate and repeatable measurement of a semiconductor wafer roughness of in the nanometer range can be readily obtained. [ABSTRACT FROM AUTHOR]