Fourier Transform Infrared (FTIR) spectroscopy is a label-free analytical technique used to evaluate the chemical profile of a sample based on its molecular vibrations. The potential dermatological applications of FTIR spectroscopy has been well demonstrated over the past decades through many proof-of-concept studies evaluating cancerous and non-cancerous cutaneous diseases. Considering that the correctly identification of skin components plays an important role in the study of cutaneous diseases, the present study aims to evaluate the spectrochemical signatures of dermis and epidermis based on the pixels of a FTIR hyperspectral image collected from healthy skin.
In this study, FTIR spectroscopy was used to evaluate the overall biochemical status of necrotic tissue areas of cutaneous squamous cell carcinoma chemically-induced on mice. FTIR hyperspectral image collected from specimen showed high correlation with the photomicrograph obtained by light microscopy, in which we were able to identify clusters associated to keratin, necrosis and regions with no tissue. Alterations in the protein content were documented in the necrotic tissue areas, indicating changes on protein conformation.
Nonmelanoma skin cancers are the most common form of malignancy in humans. Between the traditional treatment ways, the photodynamic therapy (PDT) is a promising alternative which is minimally invasive and do not requires surgical intervention or exposure to ionizing radiation. The understanding of the cascade of effects playing role in PDT is not fully understood, so that define and understand the biochemical events caused by photodynamic effect will hopefully result in designing better PDT protocols. In this study we investigated the potential of the FTIR spectroscopy to assess the biochemical changes caused by photodynamic therapy after 10 and 20 days of treatment using 5-aminolevulinic acid (ALA) as precursor of the photosensitizer photoporphyrin IX (PpIX). The amplitude values of second derivative from vibrational modes obtained with FTIR spectroscopy showed similar behavior with the morphological features observed in histopathological analysis, which showed active lesions even 20 days after PDT. Thus, the technique has the potential to be used to complement the investigation of the main biochemical changes that photodynamic therapy promotes in tissue.
Photodynamic therapy (PDT) has become a promising alternative for treatment of skin lesions such as squamous cell carcinoma. We propose a method to monitor the effects of PDT in a noninvasive way by using the optical attenuation coefficient (OAC) calculated from optical coherence tomography (OCT) images. We conducted a study on mice with chemically induced neoplastic lesions and performed PDT on these lesions using homemade photosensitizers. The response of neoplastic lesions to therapy was monitored using, at the same time, macroscopic clinical visualization, histopathological analysis, OCT imaging, and OCT-based attenuation coefficient measurement. Results with all four modalities demonstrated a positive response to treatment. The attenuation coefficient was found to be 1.4 higher in skin lesions than in healthy tissue and it decreased after therapy. This study shows that the OAC is a potential tool to noninvasively assess the evolution of skin neoplastic lesions with time after treatment.
The cutting of bone is routinely required in medical procedures, especially in dental applications. In such cases, bone
regeneration and new bone quality can determine the success of the treatment. This study investigated the main spectral
differences of undamaged and healed bone using the ATR-FTIR spectroscopy technique. Three rabbits were submitted
to a surgical procedure; a small piece of bone (3x3 mm2) was removed from both sides of their jaws using a high speed
drill. After 15 days, the rabbits were euthanized and the jaws were removed. A bone slice was cut from each side of the
jaw containing regions of undamaged and newly formed bone, resulting in six samples which were polished for
spectroscopic comparison. The samples were analyzed by FTIR spectroscopy using a diamond ATR accessory. Spectral
characteristics were compared and particular attention was paid to the proportion of phosphate to amide I bands and the
width of the phosphate band. The results show that the ratio of phosphate to amide I is smaller in new bone tissue than in
the undamaged bone, indicating a higher organic content in the newly formed bone. The analysis of the width of the
phosphate band suggests a crystallinity difference between both tissues, since the width was higher in the new bone than
in the natural bone. These results suggest that the differences observed in bone aging processes by FTIR spectroscopic
can be applied to the study of healing processes.
Introduction: New technologies in dental practice, such as laser, have enabled new strategies to be established in dental
education. The aim of this study was to analyze the difficulties that dental students encountered with performing surgical
incisions using Er:YAG laser (LE), and the morphology of these incisions. Material and Methods: Sixteen undergraduate
dental students and ten dental professionals (DP) enrolled at The Master of Science Program in Laser Dentistry were
asked to perform 15 incisions using an LE and 15 with a conventional scalpel. The incisions were compared, based on
the shape factor (relation between area and perimeter), which was obtained by a digital image system and by a
morphometry software. Data was submitted to statistical analysis of variance (p 0.05). Results: Considering the incisions
performed by scalpel, DP showed statistically significant differences (p < 0.01) in relation to control group (CG).
Considering the LE, all groups showed significant differences (p<0.0001) in relation to CG, especially the DP group. The
main laser technical failures were performing an incision that was not in a straight line, without defined borders, using an
inconstant cutting speed, and absence of suction and water jet appliances. None of the groups performed adequate
incisions using LE. Conclusion: Greater emphasis is required in relating laser therapy practice to the physical properties
of laser, particularly for dental professionals that specialize in laser.
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