PEDRO ARTHUR AUGUSTO DE CASTRO

PEDRO ARTHUR AUGUSTO DE CASTRO

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Differentiation of bone submitted to single dose from fractional of ionizing radiation by ATR-FTIR spectroscopy
2024 - GERMANO, G.; CASTRO, P.A.A. de; DIAS, D.A.; VELOSO, M.N.; ZEZELL, D.M.
Assessment of bound water of saliva samples by using FT-IR spectroscopy
2022 - FERREIRA, MARIA C.C.; MONTEIRO, GABRIELA R.; PERALTA, FELIPE; CASTRO, PEDRO A.A.; ZEZELL, DENISE; NOGUEIRA, MARCELO S.; CARVALHO, LUIS F.C.S.
The objective of the present work is to show the relationship of the high-wavenumber spectral region concern OH vibrations, which show in a way how bound water can be altered in different sample groups.
Bone as a biomarker for detecting low dose of ionizing radiation
2022 - CASTRO, PEDRO A.A. de; DIAS, DERLY A.; VELOSO, MARCELO N.; ZEZELL, DENISE M.
FTIR spectroscopy was able to discriminate bone samples receiving low-dose ionizing radiation doses (0.002 kGy, 0.004 kGy, 0.007 kGy), offering valuable insights in view of the understanding of radiation dose response in biological systems.
Nd:YAG laser on dental enamel in the reduction of artificial caries demineralization
2019 - ZEZELL, DENISE M.; SILVA, MATEUS R.; CASTRO, PEDRO A.A.; SILVA, TANIA M.; GONCALVES, SERGIO E.P.
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.
Biochemical characterization of saliva of smoking and non-smoking patients by using Fourier-transform infrared spectroscopy
2022 - FERREIRA, MARIA C. de M.S.C.; LEAL, LEONARDO B.; NOGUEIRA, MARCELO S.; CASTRO, PEDRO A.A.; PERALTA, FELIPE; ZEZELL, DENISE M.; CARVALHO, LUIS F. das C. e S. de
More than 90% of oral malignant neoplasms consist of squamous cell carcinoma originated from extrinsic and/or intrinsic multifactorial etiology on the epithelium of the oral mucosa. This multifactorial etiology makes early-stage cancer detection 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 and determine their intrinsic molecular changes as well as the performance of sample differentiation by using a neural network classifier. Saliva samples were collected by spitting, homogenized and stored at -20ºC until analysis. Spectral data was collected in the fingerprint region (900cm-1 to 1800cm- 1) by using a Thermo Scientific Nicolet 6700 ATR FT-IR Spectrometer, in which 1-μl samples were placed on the crystal without additives and left to dry completely by an average time of 5 minutes. Data pre-processing and analysis was performed on the OriginPro8.5 and Orange software. Saliva-sample classification was performed with leave-one-out validation. Correctly classified instances were 72.7% for the control group, 65.5% for occasional smokers and 75% for smokers. Sample differences were observed in the peaks at 1076cm-1 (skeletal cis conformation of DNA and symmetric stretching of phosphate [PO2], 1403cm-1 symmetric CH3 modes of protein methyl groups and δsCH3 of collagen, 1451cm- 1 asymmetrical CH3 bending modes of the protein methyl groups, 1547cm-1 of protein band, amide II, peptide and proteins amide II, and 1646cm-1 amide I, C5 methylated cytosine, C==O bond, C==C stretching uracil and NH2 guanine.
Machine Learning methods for micro-FTIR imaging classification of human skin tumors
2021 - DEL VALLE, MATHEUS; STANCARI, KLEBER; CASTRO, PEDRO A.A. de; SANTOS, MOISES O. dos; ZEZELL, DENISE M.
This review presents some methods applied to micro-FTIR imaging for classification of human skin tumors. It is a collection of the pre-processing pipeline and machine learning classification models. The aim of this review is to update and summaiize the current methods which an applied in our skin tumor research.
Healing status of bum wound healing
2021 - CASTRO, PEDRO; ZORN, TELMA; ZEZELL, DENISE
The purpose of this study is to use infrared spectroscopy (FTIR) for monitoring biological changes in burned skin. Wistar rats dorsum samples were compared to healthy group samples at 7, 14, 21 days after burn. Proteins changes of burn wounds were monitored by area under the curve (AUC) of bands at 1630 cm 1 , 1543 cm 1 and 1743 cm 1 . Kruskal-Wallis normality tests, unpaired t test with Welch's correction were used to evaluate the differences between AUC. These bands suggest association between collagen activity during wound healing stages. Our result indicates progressive recovery of 7,14 and 21 days tissues when compared with the healthy group.
Infrared Spectroscopy evaluation of burn wound healing
2019 - CASTRO, PEDRO A.A. de; ZEZELL, DENISE M.
Wound healing is a biological response in order to recover the tissue stability after injury. The impaired healing by thirddegree, 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, timeconsuming 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.
Effect of Er,Cr:YSSG laser on dental Veneers removal submitted to gamma radiation
2019 - ZANINI, NATHALIA; RABELO, THAIS F.; ZAMATARO, CLAUDIA B.; JUVINO, AMANDA C.; KUCHAR, NIELSEN G.; CASTRO, PEDRO A.A. de; ANA, PATRICIA A. da; ZEZELL, DENISE M.
The search for aesthetical rehabilitive treatment such as porcelain veneers is increasing over the past years. After CEP-FOUSP approval, the present study investigated the debonding of 20 ceramic fragments of lithium disilicate(5x5x1 mm) from human dental enamel bond with Variolink ® N. The samples were splitted in two groups: control (without gamma irradiation) and treatment (gamma irradiation: GL). EDS and FTIR was performed on enamel in both groups, before and after treatment. After cementation of the ceramic fragments the control group was only irradiated with Er, Cr: YSGG laser (λ = 2.78 nm) to remove the fragments, whereas the GL was gamma irradiated with 0.07 kGy followed by laser irradiation Er, Cr: YSGG for removal of laminates.The laser parameters were previously determined as follows: 3.5 W. The gamma and laser (GL) group was exposed to gamma radiation and the erbium laser was applied in both groups to remove lithium disilicate laminates from human dental enamel. Thus, the load required to remove the laminates after simulation of the radiotherapy treatment in the human dental enamel was analyzed by mechanical assay. In this assay, the GL group presented higher loads for the removal of the laminates compared to the control group. This indicates that the gamma radiation induces a water radiolysis by modifying the hybrid layer of the adhesive cement and increases the bond between the enamel and the resin cement, which hinders the laser debonding of the laminates.
FTIR analysis of human dentin submitted to gamma radiation
2019 - KUCHAR, NIELSEN G.; ZAMATARO, CLAUDIA B.; CASTRO, PEDRO A.A. de; RABELO, THAIS F.; JUVINO, AMANDA C.; ZANINI, NATHALIA; ZEZELL, DENISE M.
Global data indicate that head and neck cancer express one of the sixth most common types of malignant cancers. In 2030, head and neck cancer predict 1,031,439 new cases per year around the world. Radiation therapy is used as a major therapy step in the treatment protocol for head and neck malignancies. Radiation caries consists in a side effect of xerostomia, ie a considerable reduction in the quantity and quality of saliva in the oral cavity, being defined as a type of cavity that advance severely with fast progression being able to injure the dental pulp. Gamma radiation effects can promote changes associated to modification in the enamel prismatic structure, the reduction in surface microhardness and biochemically alterations in the tooth composition. However, other studies where the human dental enamel using ionizing radiation present no differences found in the integrity of the dental enamel and there was no interference in the surface microhardness. In this study, 20 human dentin samples were evaluated, split randomly into the control group and irradiated group at 25 kGy, in the Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The FTIR shows that no significant changes were found in the Phosphate band representing the inorganic material. On the other hand, the Amide I band -chosen as the representative of the organic matrix composed mainly of collagen- showed a significant difference, suggesting a degradation of the organic content. These findings corroborate with SEM analysis after the gamma irradiation dose at 25 kGy.