Early-stage cancer detection is challenging due to the lack of associated oral-tissue clinical features and absence of changes on conventional cellular-imaging, serological and histopathological exams. By using a molecular-sensitive optical technique such as Fourier-transform infrared (FT-IR) spectroscopy, disease-specific biochemical changes can be detected non-destructively, non-invasively and with small sample volumes. In this study, we have used FT-IR spectroscopy to analyze saliva samples of control, smoker, and occasional smoker groups in the fingerprint region (900cm-1 to 1800cm-1). Saliva-sample classification was performed with a neural network algorithm and leave-one-out validation. Correctly classified instances were 72.7% for the control group, 65.5% for occasional smokers and 75% for smokers.
Nd:YAG-laser associated to a photoabsorber, in the reduction of artificial caries in enamel was evaluated. Eighty bovine specimens with 6mm diameter and 2mm high were obtained and a half of the surface of each was protected as a control. Microdurometer and FTIR were performed initially and 8 groups (n=10) were obtained according to treatments: G1(- control): no-treatment; G2(+control): fluorophosphate; G3(Nd:YAG 60mJ/pulse, 10Hz, 48J/cm2, non-contact); G4(photoabsorber + Nd:YAG 60mJ); G5(Nd:YAG 80mJ/pulse, 10Hz, 64J/cm2); G6(photoabsorber + Nd:YAG 80mJ); G7(Nd:YAG 100mJ/pulse, 10Hz, 80J/cm2); G8(photoabsorber + Nd:YAG 100mJ). De-remineralization cycle were performed for induction of artificial caries and to interferometer, microdurometer and FTIR. Microhardness data were submitted to 2-way ANOVA and Tukey/Dunnett tests 5%. Statistically differences were obtained in the photoabsorberfactor individually and in the interaction between laser and photoabsorber. There was a lower percentage of microhardness loss in the groups with photoabsorber; G8 presented microhardness similar to G2. FTIR data were submitted to T-test 5%. Compared with G2, higher concentrations of carbonate were found in G4, G6 and G8; phosphate in G8; lower Amide-I concentration at G8 and higher Carbonate/Phosphate ratio at G4 and G6. The interferometry results were submitted to 3-way ANOVA of repeated measures 5%. There were statistically differences in the photoabsorber-factor individually and in the time-factor. Photoabsorber decreased the demineralization; Nd:YAG-laser without photoabsorber were less effective than fluoride; Nd:YAG-laser 100mJ with photoabsorber was as effective as fluoride and; the Nd:YAG-laser, associated or not to the photoabsorber, was no more effective than fluoride in the reduction of artificial decay.
Wound healing is a biological response in order to recover the tissue stability after injury. The impaired healing by third-degree, when the damage achieves the major part of dermis, is defined in four sequential and overlapping phases: Inflammation, transition, proliferative and maturative1. The role of biochemical cascade associated in each phase are still not fully understood, thus systematic evaluations tests are crucial. In fact, the gold standard to interrogate the molecular signature of wound healing is concern on immunohistochemical analysis. This approach tends to be laborious, time-consuming and require multiple assays2. Since Fourier transform infrared spectroscopy (FTIR) has been demonstrated in other studies to provide molecular change report upon biological samples, the present study aims to estimate the feasibility of FTIR to discriminate healthy and burned skin throughout wound stages.
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.
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