Homeopatia na Senescência / Senilidade: Modelo experimental / Homeopathy in Senescence / Senility: Experimental Model

O processo de envelhecimento é contínuo para humanos e animais e é de importância o estudo de medicamentos que possam auxiliar nesta fase. O objetivo deste trabalho foi avaliar a ação de medicamentos homeopáticos na melhora de tarefas cognitivas, locomoção e avaliação da densidade mineral óssea. Foram utilizados 32 ratos Wistar, machos, com 22 a 23 meses de idade, divididos em 4 grupos e os medicamentos ministrados foram: Calcarea carbônica 30 cH; Baryta muriática 30 cH; Solução hidroalcoólica 10%; Controle Branco. Os animais passaram pelo Campo Aberto (CA), no dia 1 do experimento e após 40 dias de medicação pelos testes Campo Aberto (CA), Labirinto em “T” e reconhecimento de objetos. Após a retirada do fêmur, a densidade mineral foi determinada por números em uma escala de cinza 8 bits em 13 pontos normalizados em 3 áreas do fêmur. No início do experimento não houve diferença estatística entre os grupos no CA. Após a medicação, foi observado aumento dos quadrantes andados no CA (p?0.05), na locomoção total e diminuição do Freezing dos grupos da Calcarea carbônica e Baryta muriática em comparação aos grupos Controle branco e Solução hidroalcoólica. O grupo Baryta muriatica demonstrou maior número de acertos no Teste do Labirinto em T. Não foram observados efeitos significativos do tratamento sobre a densidade mineral óssea na região proximal, distal e média. Os medicamentos foram capazes de aumentar a locomoção dos animais mesmo sem alteração na densidade óssea e a Baryta muriática agiu na melhora cognitiva dos animais em comparação aos outros grupos

Fast dose calculation for stereotactic synchrotron radiotherapy

International audienc

Simulation of dose deposition in stereotactic synchrotron radiation therapy: a fast approach combining Monte Carlo and deterministic algorithms.

International audienceA hybrid approach, combining deterministic and Monte Carlo (MC) calculations, is proposed to compute the distribution of dose deposited during stereotactic synchrotron radiation therapy treatment. The proposed approach divides the computation into two parts: (i) the dose deposited by primary radiation (coming directly from the incident x-ray beam) is calculated in a deterministic way using ray casting techniques and energy-absorption coefficient tables and (ii) the dose deposited by secondary radiation (Rayleigh and Compton scattering, fluorescence) is computed using a hybrid algorithm combining MC and deterministic calculations. In the MC part, a small number of particle histories are simulated. Every time a scattering or fluorescence event takes place, a splitting mechanism is applied, so that multiple secondary photons are generated with a reduced weight. The secondary events are further processed in a deterministic way, using ray casting techniques. The whole simulation, carried out within the framework of the Monte Carlo code Geant4, is shown to converge towards the same results as the full MC simulation. The speed of convergence is found to depend notably on the splitting multiplicity, which can easily be optimized. To assess the performance of the proposed algorithm, we compare it to state-of-the-art MC simulations, accelerated by the track length estimator technique (TLE), considering a clinically realistic test case. It is found that the hybrid approach is significantly faster than the MC/TLE method. The gain in speed in a test case was about 25 for a constant precision. Therefore, this method appears to be suitable for treatment planning applications

Monte Carlo code comparison of dose delivery prediction for microbeam radiation therapy

Preclinical Microbeam Radiation Therapy (MRT) research programs are carried out at the European Synchrotron Radiation Facility (ESRF) and at a few other synchrotron facilities. MRT needs an accurate evaluation of the doses delivered to biological tissues for carrying out pre-clinical studies. This point is crucial for determining the effect induced by changing any of the physical irradiation parameters. The doses of interest in MRT are normally calculated using Monte Carlo (MC) methods. A few MC packages have been used in the last decade for MRT dose evaluations in independent studies. The aim of this investigation is to provide a preliminary basis to perform a systematic comparison of the dose results obtained, under identical irradiation conditions and for the same scoring geometries with the following five MC codes: EGS4, PENELOPE, GEANT4, EGSnrc, and MCNPX. Dose profiles have been calculated in an in-depth region of cylindrical phantoms made of water or PMMA. Beams in both cylindrical and planar geometry have been considered. This comparison shows an overall agreement among the different codes although minor differences occur, which need further investigations

Diabetes Affects Antibody Response to SARS-CoV-2 Vaccination in Older Residents of Long-term Care Facilities: Data From the GeroCovid Vax Study

Objective: Type 2 diabetes may affect the humoral immune response after vaccination, but data concerning coronavirus disease 19 (COVID-19) vaccines are scarce. We evaluated the impact of diabetes on antibody response to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination in older residents of long-term care facilities (LTCFs) and tested for differences according to antidiabetic treatment. Research design and methods: For this analysis, 555 older residents of LTCFs participating in the GeroCovid Vax study were included. SARS-CoV-2 trimeric S immunoglobulin G (anti-S IgG) concentrations using chemiluminescent assays were tested before the first dose and after 2 and 6 months. The impact of diabetes on anti-S IgG levels was evaluated using linear mixed models, which included the interaction between time and presence of diabetes. A second model also considered diabetes treatment: no insulin therapy (including dietary only or use of oral antidiabetic agents) and insulin therapy (alone or in combination with oral antidiabetic agents). Results: The mean age of the sample was 82.1 years, 68.1% were women, and 25.2% had diabetes. In linear mixed models, presence of diabetes was associated with lower anti-S IgG levels at 2 (β = -0.20; 95% CI -0.34, -0.06) and 6 months (β = -0.22; 95% CI -0.37, -0.07) after the first vaccine dose. Compared with those without diabetes, residents with diabetes not using insulin had lower IgG levels at 2- and 6-month assessments (β = -0.24; 95% CI -0.43, -0.05 and β = -0.30; 95% CI -0.50, -0.10, respectively), whereas no differences were observed for those using insulin. Conclusions: Older residents of LTCFs with diabetes tended to have weaker antibody response to COVID-19 vaccination. Insulin treatment might buffer this effect and establish humoral immunity similar to that in individuals without diabetes