Fibroblast-populated collagen lattices (FPCL) are widely used in tissue-engineered artificial skin substitutes, but their main drawback is that interaction of fibroblasts and matrix causes contraction of the lattice, reducing it to about 20% of its original area. The effect of low-level laser treatment (LLLT) on the behavior of 3T3 fibroblasts seeded in collagen lattices containing 20% chondroitin-6-sulphate was investigated to determine whether LLLT could control the contraction of FPCL. A He-Ne laser was used at 632.8 nm to deliver a 5-mW continuous wave with fluences from 1 to 4 J/cm2. Laser treatment at 3 J/cm2 increased contraction of collagen lattices in the absence of cells but decreased contraction of cell seeded lattices over a 7-day period. The effect was energy dependent and was not observed at 1, 2, or 4 J/cm2. There was no alteration in fibroblast viability, morphology, or mitochondrial membrane potential after any laser treatments, but the distribution of actin fibers within the cells and collagen fibers in the matrices was disturbed at 3 J/cm2. These effects contribute to the decrease in contraction observed. LLLT may offer a means to control contraction of FPCL used as artificial skin substitutes.
In this paper, we address the problem of spectral data sampling in Fourier domain optical coherence
tomography (FD-OCT). The interferometric information in a Fourier Domain OCT system is retrieved from spectral
measurements made using a linear array spectrometer. In such spectrometers, spectral data are available as an array
of points equally spaced in the wavelength domain. To obtain the spatial profile, the spectral data have to be
converted to the frequency domain before applying the Fourier transform. The inverse relationship between these
domains causes an unequal spacing of data points after the spectral data is converted to the frequency domain,
resulting in the degradation of the FD-OCT images. The current practice typically utilizes zero-padding and spline
interpolation to circumvent this problem. While these algorithms do improve the FD-OCT images, our
investigations showed that more can be done to enhance the images. Toward this end, we propose a signal
processing algorithm based on non-uniform discrete Fourier transform (NUDFT). The results of our algorithm are
compared against the current algorithms on both simulated and experimental results.
Glial fibrillary acidic protein (GFAP) is a traditional biomarker for astrocytes of the central nervous system. In
this study, non-invasive in vivo imaging of GFAP-GFP (green fluorescent protein) expression in the brain of
neonatal transgenic mice is used as a novel method to investigate the relationship between the expression of the
transgene at 0, 2, 4, 6 and 8 hr post-treatment in mice subjected to a single administration of 12 mg/kg of
neurotoxin 1-methyl-4(2'-methylphenyl)-1,2,3,6-tetrahydropyridine (2'-CH3-MPTP). The GFP elevation was
found to peak at 6 hr and lasted to at least 8 hr after the toxin treatment. Histological examination of fixed brain
sections using immunohistochemistry (IHC) shows an increase in GFP and GFAP signal from the substantia
nigra pars compacta (SNpc) and the hippocampus. The results have provided quantitative fluorescence and
qualitative histological evidence for the activation of the GFAP-GFP transgene in astrocytes following
neurotoxin 2'-CH3-MPTP administration, suggesting that the model described here could be used to study
neuronal degeneration such as Parkinson's disease and in general, developmental neurotoxicity in live animals.
With the rapid development of tissue engineering and gene therapy, collagen-based biomaterials are frequently used as cell transplant devices; an example is tissue-engineered skin substitutes. In this study of low level laser therapy (LLLT) we determined the influence of the irradiation and treatment parameters on the proliferation rate of 3T3 mouse fibroblast cells cultured on collagen-glycosaminoglycan (GAG) lattices and Petri dishes for up to 4 and 7 days respectively. Helium-Neon (He-Ne) laser at 1 - 4 J/cm2 was used to irradiate the cells. Using 5-carboxyfluorescein diacetate (CFDA) fluorescence, studies on the proliferation rate of irradiated cells before and after cell attachment, and on different treatment days were conducted. The viability of cells on collagen-GAG lattices were assessed using the MTT assay. It was found that in terms of cell proliferation, the cells irradiated at different fluences and treatment modes (at 3 J/cm2) showed no statistically significant difference from the control cells. Control cells on collagen-GAG lattices were found to be more viable than the irradiated cells. It was concluded that with existing experimental conditions, LLLT was found to have no statistically significant effect on the post-cell attachment proliferation and viability of 3T3 mouse fibroblast cells.
Interstitial laser thermotherapy is a minimally invasive surgical procedure that utilizes laser to coagulate and treat benign prostatic hyperplasia. This study explores the use of a computer-assisted interstitial laser coagulation system to aid surgeons in performing this procedure.
A longer operating time and steeper learning curve in mastering the techniques for transurethral laser resection of the prostate are the main problems faced by surgeons compared to standard transurethral resection of the prostate (TURP). However, these disadvantages can be solved with the introduction of a treatment modality designed and developed based on an integrated system of computer, robotics and laser technology. In vitro experiments were carried out to determine variables affecting the vaporization and coagulation lesions, in order to identify the parameters that could optimize this modality. Human cadaveric prostate and fresh chicken breast tissues were irradiated with different parameters using continuous wave Nd:YAG laser fiber in contact with the tissue. The effects of irrigant flowrate, fiber/tissue angle of inclination, number of passes, direction, speed and power of lase on the volume of tissue vaporized and coagulated, were assessed. A non-contact optical coordinate measuring machine was used to measure the depth and width of the vaporized and coagulated lesion. Results reveal that for each directional vaporization path (forward, clockwise and counter-clockwise), power and speed of lase are the most significant parameters influencing the volume of the vaporized and coagulated lesion. Optimized values of the power and speed of lase at 100 W and 1 - 3 mm/s respectively were obtained from the experiments when the tissues were irradiated in the forward, clockwise and counter-clockwise directions. It was concluded from our study to quantify tissue removal and damage, optimized values of irradiation power and speed could be obtained and implemented in the procedure of transurethral robotic laser resection of the prostate.
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