Broad-Band, Intensity-Dependent Absorption In Tetravalent Chromium-Doped Crystals

Cr4+ -doped Y2SiO5 and Ca2Al2SiO7 have been investigated as broadband, solid state saturable absorbers. Saturation properties in the near infrared as well as a demonstration of tunable, passive Q switching of a flash-lamp pumped Cr:LiSAF laser are discussed

Optical absorption, absorption saturation and a useful figure of merit for chromium doped glasses

Chromium-doped aluminate and silicate glasses have been prepared in both inert and oxidizing atmospheres. Spectroscopic measurements indicate that some of the glasses incorporated the chromium ion in the +4 valence state. These Cr4+ doped glasses exhibit a broad spectral emission covering the communication window and the eye safe region around 1.5 μm. Ten glass samples and two crystalline materials, were used to study the phenomenon of saturable absorption in the Cr4+ ion. A figure of merit was defined to compare the performance of different materials as saturable absorbers. The preparing conditions that lead to a glass saturable absorber with better figure of merit have been investigated. A Q-switched Cr: LiSAF laser was used for the saturable absorption measurements. Copyright © 1996 Elsevier Science Ltd

Magneto-optical rotation of heavy-metal oxide glasses

Magneto-optical rotation was measured at room temperature for glasses containing Bi2O3-CdO-GeO2 (BCG), and Bi2O3-PbO-GeO2-B2O3 (BPGP). A pulsed magnetic field between 50 and 80 KG was used to measure Faraday rotation at 632.8 nm as a function of the concentration of Bi and Cd for BCG and Bi and Pb for BPGB. Verdet constant as high as 0.162 min G-1 cm-1 at 632.8 nm for the BPGB sample with the highest concentrations of Bi and Cd was found. Verdet constant increases linearly with the heavy-metal concentration for the BPGB whereas it reaches some saturation for the BCG system. Measurements of the magneto-optical rotation at other wavelengths in the visible and the refractive index at 632.8 nm are also reported. © 1998 Elsevier Science B.V. All rights reserved

Near-infrared Raman spectroscopy to detect anti-Toxoplasma gondii antibody in blood sera of domestic cats: quantitative analysis based on partial least-squares multivariate statistics

Toxoplasmosis is an important zoonosis in public health because domestic cats are the main agents responsible for the transmission of this disease in Brazil. We investigate a method for diagnosing toxoplasmosis based on Raman spectroscopy. Dispersive near-infrared Raman spectra are used to quantify anti-Toxoplasma gondii (IgG) antibodies in blood sera from domestic cats. An 830-nm laser is used for sample excitation, and a dispersive spectrometer is used to detect the Raman scattering. A serological test is performed in all serum samples by the enzyme-linked immunosorbent assay (ELISA) for validation. Raman spectra are taken from 59 blood serum samples and a quantification model is implemented based on partial least squares (PLS) to quantify the sample's serology by Raman spectra compared to the results provided by the ELISA test. Based on the serological values provided by the Raman/PLS model, diagnostic parameters such as sensitivity, specificity, accuracy, positive prediction values, and negative prediction values are calculated to discriminate negative from positive samples, obtaining 100, 80, 90, 83.3, and 100%, respectively. Raman spectroscopy, associated with the PLS, is promising as a serological assay for toxoplasmosis, enabling fast and sensitive diagnosis. (C) 2010 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3463006]Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Low-Level Laser Therapy Associated to N-Acetylcysteine Lowers Macrophage Inflammatory Protein-2 (MIP-2) mRNA Expression and Generation of Intracellular Reactive Oxygen Species in Alveolar Macrophages

Objective: the aim of this work was to investigate the low-level laser therapy (LLLT) effect on alveolar macrophages (AM) activated by oxidative stress and lipopolysaccharide (LPS). Background data: LLLT has been reported to actuate positively relieving the late and early symptoms of airway and lung inflammation. It is not known if the increased MIP-2mRNA expression and intracellular reactive oxygen species (ROS) generation observed in acute lung inflammation (ALI) can be influenced by LLLT. Materials and Methods: Rat AM cell line (AMJ2-C11) was cultured with LPS or H(2)O(2) and laser irradiated. MIP-2mRNA and ROS production in the AM were evaluated by Real Time-PCR and the 2',7'-dichlorofluorescin diacetate (DCFH-DA) respectively. the NF-kappa B protein in the AM was measured by the enzyme linked immunoassay method. To investigate the antioxidant effect of laser, the AM were prebathed with N-acetylcysteine (NAC) and then irradiated with laser. LLLT was also studied in the presence of an inhibitor of NF-kappa B (BMS 205820). in addition, the effect of LLLT on NF-kappa B protein was investigated. Results: LLLT attenuated the MIP-2mRNA expression and intracellular ROS generation after LPS or H(2)O(2). When the AM were pretreated with NAC, the laser effect was potentiated. BMS 205820 suppresses the effect of LLLT on MIP-2mRNA expression and ROS generation, stimulated by LPS or H(2)O(2). On NF-kappa B transcription factor, both the LLLT and NAC reduced this protein in the AM exposed to LPS or H(2)O(2). the synergistic effect between LLLT and NAC on the reduction the NF-kappa B was also evidenced. Conclusion: Results indicate that there is a synergistic action of LLLT with NAC on MIP-2mRNA expression from LPS-or H(2)O(2)-stimulated AM, and that both ROS intracellular generation and NF-kB signaling seem to be involved.UNIVAP, IP&D, Inst Res & Dev, São Paulo, BrazilUniv Camilo Castelo Branco UNICASTELO, Inst Biomed Engn, São Paulo, BrazilCtr Univ Nove de Julho UNINOVE, Rehabil Sci Dept, São Paulo, BrazilInst Biomed Sci, Dept Pharmacol, São Paulo, BrazilIOC, Lab Immunopharmacol, Rio de Janeiro, BrazilSão Paulo Fed Univ UNIFESP, Dept Sci & Technol, São Paulo, BrazilSão Paulo Fed Univ UNIFESP, Dept Sci & Technol, São Paulo, BrazilWeb of Scienc

The effect of low intensity laser therapy on wound healing in Streptozotocin-induced diabetic rats

Diabetes Mellitus is a condition that results in a delay of the wound healing process, that is associated with an insufficient production of collagen, a decrease of the amount of collagen fibrils and deficient blood flow in the wound area. It is suggested that Low Intensity Laser Therapy acts by improving wound healing in normal organisms, accelerating tissue regeneration. The aim of this work was to investigate the biostimulatory effect of the HeNe laser irradiation, at 632.8 nm, on wound healing in 15 male rats suffering from diabetes induced by Streptozotocin, compared to 15 control diabetic animals. Irradiation parameters were: laser power of 15mW, exposition time of 17 s., irradiated area of 0.025 cm 2 and laser energy density of 10 J/cm 2. Full-thickness skin squared samples, with 5 mm of non-injured tissue around the wound, were obtained at 4, 7 and 15 days after wounding procedure (5 treated and 5 control animals each time). The histopathologic analysis performed by haematoxylin-eosin staining. Results suggested that the irradiation of diabetic rats was efficient for wound healing. Treated group presented better quality of the wound tissues by the macroscopic observation than control group and the microscopic analysis demonstrated that treated animals had better histopathologic evaluation than non treated

Comparison between wound healing in induced diabetic and nondiabetic rats after low-level laser therapy

Objective: the aim of this work was to compare the effect of low-level laser therapy (LLLT) on the wound healing process in nondiabetic and diabetic rats. Background Data: Among the clinical symptoms caused by diabetes mellitus, a delay in wound healing is a potential risk for patients. It is suggested that LLLT can improve wound healing. Methods: the tissue used for this study was extracted from animals suffering from diabetes, which was induced by Streptozotocin (R), and from nondiabetic rats. Animals were assembled into two groups of 25 rats each (treated and control) and further subdivided into two groups: diabetic (n = 15) and nondiabetic (n = 10). A full-thickness skin wound was made on the dorsum. area, with a round 8-mm hole-punch. The treated group was irradiated by a HeNe laser at 632.8 nm, with the following parameters: 15 mW, exposition time of 17 sec, 0.025 cm(2) irradiated area, and energy density of 10 J/cm(2). Square full-thickness skin samples (18 mm each side, including both injured and noninjured tissues) were obtained at 4, 7, and 15 days after surgery and analyzed by qualitative and quantitative histological methods. Results: Quantitative histopathological analysis confirmed the results of the qualitative analysis through histological microscope slides. When comparing tissue components (inflammatory cells, vessels and fibroblast/area), we found that treated animals had a less intense inflammatory process than controls. Conclusion: Results obtained by both qualitative and quantitative analyses suggested that irradiation of rats with HeNe (632.8 nm), at the tested dose, promoted efficient wound healing in both nondiabetic and diabetic rats as, compared to the control group