Abstract
Current biophotonics methods cover the entire optical spectrum from the deep ultraviolet to the terahertz. To optimize such methods for diagnostic and therapeutic applications, the need to obtain the wideband dispersion of tissues is high. The pancreas is a very important organ in the human body, since it produces insulin and its malfunction may induce diabetes. A reduced number of biophotonics publications regarding the pancreas is available, meaning that studies to determine its optical properties and their variation during optical clearing treatments are necessary. Considering this fact, we used the total internal reflection method to measure the refractive index of the rabbit pancreas for wavelengths between 400 and 850 nm. The experimental results allowed to calculate the pancreas dispersion with the Cauchy, Conrady and Cornu equations. It was observed that all those equations provided good data fitting in the spectral range of the measurements, but differences were observed outside these limits. Considering the wavelength of 633 nm, the mean value from the three dispersions was 1.3521, while the one published for porcine pancreas is 1.3517. The dispersion calculated with the Conrady equation does not present a fast decreasing behavior for shorter wavelengths as the ones calculated with the Cauchy and Cornu equations, but comparing these curves with a dispersion for a tissue-like material, all seem to have good agreement.

Abstract
In this paper we present three studies that demonstrate the applicability of spectroscopy methods and optical clearing treatments in pathology identification and monitoring. In the first study, by obtaining the absorption spectra of human healthy and pathological (adenocarcinoma) colorectal mucosa tissues, it was possible to identify a higher content of a pigment in the diseased tissues. This study also shows that machine learning methods can be used to reach the same differentiated results in vivo through diffuse reflectance spectroscopy. In the second study, the combination of collimated transmittance spectroscopy with optical clearing treatments allowed to obtain the diffusion coefficients of glucose in healthy and pathological colorectal mucosa as: Dglucose10´=5.8–7 cm2 /s and Dglucose10´=4.4–7 cm2/s, respectively. This study also demonstrated that the diseased tissues contains about 5% more mobile water than the healthy tissues. The third study was performed to evaluate the protein dissociation mechanism of optical clearing. By treating both healthy and pathological colorectal mucosa tissues with 93%-glycerol, a protein dissociation rate of about 3 times higher was obtained for the pathological mucosa. All the discriminating parameters that result from these studies can be obtained in the in vivo situation through diffuse reflectance spectroscopy and further studies to evaluate their values in different stages of cancer progression are of great importance to develop disease monitoring protocols. © J-BPE.

Abstract
The knowledge of the optical properties of biological tissues in a wide spectral range is highly important for the development of noninvasive diagnostic or treatment procedures. The absorption coefficient is one of those properties, from which various information about tissue components can be retrieved. Using transmittance and reflectance spectral measurements acquired from ex vivo rabbit brain cortex samples allowed to calculate its optical properties in the ultraviolet to the near infrared spectral range. Melanin and lipofuscin, the two pigments that are related to the aging of tissues and cells were identified in the cortex absorption. By subtracting the absorption of these pigments from the absorption of the brain cortex, it was possible to evaluate the true ratios for the DNA/RNA and hemoglobin bands in the cortex—12.33-fold (at 260 nm), 12.02-fold (at 411 nm) and 4.47-fold (at 555 nm). Since melanin and lipofuscin accumulation increases with the aging of the brain tissues and are related to the degeneration of neurons and their death, further studies should be performed to evaluate the evolution of pigment accumulation in the brain, so that new optical methods can be developed to aid in the diagnosis and monitoring of brain diseases.

Abstract
In this paper, we describe the study of the kinetics and efficiency of the refractive index matching mechanism created by highly concentrated glycerol solutions in human normal and pathological colorectal mucosa tissues. Considering thewavelength range between 200 and 1000 nm, higher efficiency was obtained for the pathological mucosa, which shows a decreasing efficiency with increasing wavelength. The normal mucosa presents similar values in the deep-ultraviolet and in the near-infrared. Minimal efficiency values of 1% and 1.5% were obtained in the normal and pathological mucosa at 266 nm (combined absorption of DNA/RNA and myoglobin/hemoglobin bands at 260 and 274 nm) and local maxima of 2.9% and 3.8% were obtained in the same tissues at 570 nm. The diffusion time of glycerol was estimated as 417.3 +/- 5.2 s in normal mucosa and 504.9 +/- 3.8 s in pathological mucosa, suggesting that less molecules are necessary in the pathological tissue to produce a higher magnitude RI matching.

Abstract
In this paper, we describe the combination of ultraviolet (UV) spectroscopy with the optical clearing technique to induce new tissue windows, evaluate their efficiency, study the diffusion properties of agents and discriminate cancer. The use of highly concentrated glycerol solutions has induced high efficiency clearing effects in the UV, both in human colorectal and gingival tissues. The protein dissociation rate obtained for colorectal tissues was approximately 3 times higher in pathological than in normal mucosa and the kinetics of diffuse reflectance in the UV allowed to estimate the diffusion coefficient for water in gingival mucosa at glycerol action as (1.78 +/- 0.26) x 10(-6) cm(2)/s.

Abstract