Infrared laser light further improves bone healing when associated with bone morphogenic proteins: an in vivo study in a rodent model

OBJECTIVE: This study assessed histologically the effect of laser photobiomodulation (LPBM) on the repair of surgical defects created in the femurs of Wistar rats treated or not treated with bone morphogenic proteins (BMPs) and organic bovine bone graft. BACKGROUND DATA: This paper is part of an ongoing series of works in which biomaterials are used in association with LPBM. Several previous reports by our group have shown that the use of laser photobiomodulation improves the treatment of bone defects. MATERIALS AND METHODS: Forty-eight adult male Wistar rats were divided into four randomized groups: group I (control, n = 12); group II (LPBM, n = 12); group III (BMPs + organic bovine bone graft, n = 12); and group IV (BMPs + organic bovine bone graft + LPBM, n = 12). The irradiated groups received seven irradiations every 48 h, beginning immediately after the surgical procedure. The laser therapy (lambda = 830 nm, 40 mW CW, varphi = 0.6 mm) consisted of 16 J/cm(2) per session divided equally over four points (4 J/cm(2) each) around the defect. The subjects were sacrificed after 15, 21, and 30 d, and the specimens were routinely embedded in wax, stained with hematoxylin and eosin and sirius red, and analyzed under light microscopy. RESULTS: The results showed histological evidence of increased deposition of collagen fibers (at 15 and 21 d), as well as an increased amount of well-organized bone trabeculae at the end of the experimental period (30 d) in the irradiated animals versus the non-irradiated controls. CONCLUSION: The use of LPBM with BMPs and organic bovine bone grafts increases the positive biomodulating effects of laser light.     

Effectiveness of laser photobiomodulation at 660 or 780 nanometers on the repair of third-degree burns in diabetic rats

OBJECTIVE: The aim of this investigation was to compare by light microscopy the effects of laser photobiomodulation (LPBM) at lambda = 660 nm and lambda = 780 nm on third-degree burns in diabetic Wistar rats. BACKGROUND DATA: Burns are severe injuries that result in fluid loss, tissue destruction, infection, and shock, that may result in death. Diabetes is a disease that reduces the body's ability to heal properly. LPBM has been suggested as an effective method of improving wound healing. MATERIALS AND METHODS: A third-degree burn measuring 1.5 x 1.5 cm was created in the dorsum of each of 55 animals, and they were divided into three groups that were or were not treated with LPBM (lambda = 660 nm or lambda = 780 nm, 35 mW, varphi = 2 mm, 20 J/cm(2)). The treatments were started immediately post-burn at four points within the burned area (5 J/cm(2)) and were repeated at 24-hour intervals over 21 d. The animals were humanely killed after 3, 5, 7, 14, and 21 d by an overdose of intraperitoneal general anesthetic. The specimens were routinely cut and stained and analyzed by light microscopy. RESULTS: We found that healing in the animals receiving 660-nm laser energy was more apparent at early stages, with positive effects on inflammation, the amount and quality of granulation tissue, fibroblast proliferation, and on collagen deposition and organization. Epithelialization and local microcirculation were also positively affected by the treatment. CONCLUSION: The use of 780-nm laser energy was not as effective as 660-nm energy, but it had positive effects at early stages on the onset and development of inflammation. At the end of the experimental period the primary effect seen was on the amount and quality of the granulation tissue. The 660-nm laser at 20 J/cm(2), when used on a daily basis, was more effective than the 780-nm laser for improving the healing of third-degree burns in the diabetic rats beginning at the early stages post-burn.     

Post-translational modifications of Trypanosoma cruzi histone H4

Histone tails provide sites for a variety of post-translational modifications implicated in the control of gene expression and chromatin assembly. As both histones and control of gene expression in trypanosomes are highly divergent compared to most eukaryotes, post-translational modifications of Trypanosoma cruzi histones were investigated. After in vivo incubation of live parasites with radiolabeled precursors, histone H4 mainly incorporates [³H]-acetyl, and to a lesser extent [³H]-methyl residues. In contrast, histone H3 preferentially incorporates [³H]-methyl residues. The modifications of histone H4 were further characterized by mass spectrometry. MALDI-TOF–TOF-MS analysis revealed that peptides from histone H4 amino-terminus, obtained by either endoproteinase Glu-C or endoproteinase Arg-C digestion, contain isoforms with 14 and 42 Da additions, suggesting the presence of simultaneous acetylations and/or methylations. Tandem mass spectrometry analysis demonstrated that the N-terminal alanine is methylated, and lysine residues at positions 4, 10, 14 and 57 are acetylated; lysine at position 18 is mono-methylated, while arginine at position 53 is dimethylated. Immunoblotting analyses using specific antibodies raised against synthetic and acetylated peptides of T. cruzi histone H4 indicate that lysine 4 is acetylated in the majority of histone H4, while other acetylations at the N-terminus portion of histone H4 are less abundant.     

An immunofluorescence test for diagnosis of ophthalmic herpes in a mouse corneal model

Herpes simplex virus type 1 (HSV-1) ophthalmic disease is the most common cause of corneal blindness in humans world-wide. Current culture techniques for HSV take several days and commercially available HSV laboratory based diagnostic techniques vary in sensitivity. Our study was conducted to evaluate the use of a quicker and simpler method to herpes ophthalmic diagnosis. Corneal smears were made by firm imprints of infected mouse eyes to glass slides, after smears were fixated with cold acetone, and an indirect immunofluorescence (IIF) method was performed using monoclonal antibodies in a murine model of ophthalmic herpes. Eye swabs from infected mice were inoculated in Vero cells for virus isolation. Cytology and histology of the eye were also performed, using hematoxylin-eosin routine. Mouse eyes were examined by slit-lamp biomicroscopy for evidence of herpetic disease at various times postinoculation. We made a comparative evaluation of sensitivity, specificity and speed of methods for laboratory detection of HSV. Our results indicate that this IIF method is quick, sensitive, specific and can be useful in the diagnosis of ophthalmic herpes as demonstrated in an animal model.