RESUMO
Photodynamic procedures have been used in many applications, ranging from cancer treatment to microorganism inactivation. Photodynamic reactions start with the activation of a photosensitizing molecule with light, leading to the production of cytotoxic molecules that promote cell death. However, establishing the correct light and photosensitizer dosimetry for a broadband light source remains challenging. In this study, we proposed a theoretical mathematical model for the photodegradation of protoporphyrin IX (PpIX), when irradiated by multi-wavelength light sources. The theoretical model predicts the experimental photobleaching (temporal change in PpIX concentration) of PpIX for different light sources. We showed that photobleaching occurs independently of the light source wavelengths but instead depends only on the number of absorbed photons. The model presented here can be used as an important mathematical approach to better understand current photodynamic therapy protocols and help achieve optimization of the doses delivered.
RESUMO
There are few published data on the relationship between loss of bone mass due to osteoporosis and poor tooth quality. This study analyzed the effects of osteoporosis on incisor teeth and femoral bones using optical techniques in rats. Twenty female Wistar rats aged 6 months (n = 20) were randomized into two groups: control group, non-ovariectomized rats (n = 10); ovariectomy group, ovariectomized rats to induce osteoporosis (n = 10). Each group was subdivided randomly into two groups containing five rats each as follows. Control group 1: non-ovariectomized rats euthanized at the age of 9 or 3 months post-ovariectomy (n = 5); Control group 2: non-ovariectomized rats euthanized at the age of 1 year or 6 months post-ovariectomy (n = 5); ovariectomy group 1: ovariectomized rats euthanized at the age of 9 months or 3 months post-ovariectomy (n = 5); ovariectomy group 2: ovariectomized rats euthanized at the age of 1 year or 6 months post-ovariectomy (n = 5). The incisor teeth and femoral bones of Wistar rats were removed to perform Raman spectroscopy using an excitation laser at 785 nm. In addition, an energy-dispersive X-ray spectrometer system was used to evaluate calcium (Ca) and phosphorus (P). The main findings included significant changes (p < 0.05) for phosphate and carbonate band areas for both incisor teeth and femur bones. In addition, there was significant negative correlation between the P concentration and phosphate/carbonate ratio (lower P content-larger ratio, p < 0.05) for incisor teeth and femoral bones. The proline and CH2 wag band areas were significantly reduced only for the incisor teeth (p < 0.05). Therefore, Raman spectroscopy assessed the compositional, physicochemical and structural changes in hard tissue. The current study also pointed out the possible action mechanisms of these changes, bone fracture risk and dental fragility. It is important to emphasize that poor dental quality may also occur due to osteoporosis.
Assuntos
Fêmur/patologia , Incisivo/patologia , Osteoporose/patologia , Ovariectomia , Espectrometria por Raios X , Análise Espectral Raman , Animais , Densidade Óssea , Feminino , Ratos Wistar , Fatores de TempoRESUMO
Huanglongbing (HLB) is the most recent and destructive bacterial disease of citrus and has no cure yet. A promising alternative to conventional methods is to use laser-induced breakdown spectroscopy (LIBS), a multi-elemental analytical technique, to identify the nutritional changes provoked by the disease to the citrus leaves and associate the mineral composition profile with its health status. The leaves were collected from adult citrus trees and identified by visual inspection as healthy, HLB-symptomatic, and HLB-asymptomatic. Laser-induced breakdown spectroscopy measurements were done in fresh leaves without sample preparation. Nutritional variations were evaluated using statistical tools, such as Student's t-test and analysis of variance applied to LIBS spectra, and the largest were found for Ca, Mg, and K. Considering the nutritional profile changes, a classifier induced by classification via regression combined with partial least squares regression was built resulting in an accuracy of 73% for distinguishing the three categories of leaves.