Effect of different solutions in reversing the damage caused by radiotherapy in dentin structure.

BACKGROUND: Previous studies have shown that radiotherapy of the head and neck region can cause direct changes in dental structure. This study evaluated the effect of different solutions on the dentin chemical composition and collagen structure of irradiated dentin. MATERIAL AND METHODS: Sixty maxillary canines were distributed in 2 groups (n=30): non-irradiated and irradiated (radiotherapy: X-rays of 6 MV in 30 cycles of 2 Gy to 60 Gy). The teeth were sectioned, sanded, and polished to obtain 3x3x2 mm fragments, which were redistributed in 3 subgroups (n=10) according to the treatment employed: chlorhexidine 2% (CL), chitosan 0.2% (QT), and 0.5 M carbodiimide (EDC). The samples were analyzed in FTIR at time zero (T0-control) and after 1 (T1), 3 (T3), and 5 (T5) minutes of immersion in the tested solutions. The data for the areas of the carbonate (C), amide I (AI) bands, and the ratio between the areas of the amide III/proline and hydroxyproline (AIII/PH) bands were analyzed using ANOVA and Tukey test (α=5%). RESULTS: QT showed lower C values at T1, T3, and T5 (P<0.0001), presenting lower values when compared to CL and EDC subgroups (P<0.05). AI values at T3 and T5 were higher than T0-control and T1, independently of the radiotherapy and dentin treatment factors (P<0.05). At T0-control, the AIII/PH ratio was lower in the irradiated group (P<0.05), whereas the EDC treatment at T1, T3, and T5 and QT at T3 and T5 increased these values (P<0.05), making them similar to non-irradiated subgroups (P>0.05). CONCLUSIONS: Radiotherapy changes the secondary structure of collagen, and EDC was able to restore collagen integrity after 1 minute of immersion, without changing dentin inorganic composition.

Alterações da ultra-estrutura miocárdica durante cirurgia cardíaca / Ultrastructural changes of the myocardium during cardiac surgery

Os autores fazem uma revisao da ultra-estrutura miocardica normal e alterada por isquemia cardiaca e circulacao extracorporea, analisando a quantificacao das alteracoes encontradas. Admiten que o estudo da ultra-estrutura miocardica e um bom metodo para estudar a protecao miocardica durante cirurgia cardiaca

Proteção miocárdica por cardiologia sanguínea durante circulação extracorpórea. Avaliação ultra-estrutural miocárdica no cão / Myocardial protection by blood cardioplegia during extracorporeal circulation. Ultrastructural myocardial evaluation in the dog

Os autores desenvolveram metodo simplificado para infusao de cardioplegia sanguinea durante circulacao extracorporea. Fizeram estudo experimental, em caes, para averiguar a eficiencia do metodo. Dois grupos de 5 caes foram submetidos a 60 min de esquemia cardiaca, seguidos de 60 min de reperfusao coronaria. A protecao miocardica, durante isquemia cardiaca, foi obtida com o metodo de cardioplegia sanguinea no grupo I e com cardioplegia acelular gelada no grupo II. Para comparar os dois metodos empregados, foram feitas quatro biopsias de ventriculo esquerdo, para estudo ultra-estrutural: antes da isquemia cardiaca; ao fim de 60 min de isquemia cardiaca; com 30 mim de reperfusao coronaria e com 60 min de reperfusao coronaria.Nas tres primeiras biopsias houve apenas alteracoes ultra-estruturais miocardicas discretas, sem diferencas entre os dois grupos. Nas ultimas, as alteracoes ultraestruturais foram mais severas no grupo II do que no grupo I. Conclui-se que o metodo de protecao miocardica com cardioplegia sanguinea e eficaz para 60 min de isquemia cardiaca, sendo inclusive superior a cardioplegia acelular gelada

Isquemia medular por deprivacao sanguinea temporaria - estudo experimental em caes. / Spinal cord ischemia following temporary blood flow oclusion - experimental study in dogs

Os autores apresentam estudo experimental em caes, em que procuram demonstrar o papel do tempo de pincamento aortico no aparecimento da lesao medular. Estudam tambem a possibilidade de lesao, quando o suprimento sanguineo ofertado a medula ocorre em regime de hipotensao arterial

Metaphyseal dysostosis. Review of literature; study of a case with cytogenetic analysis

The clinical, pathologic, and laboratory findings of a patient with severe metaphyseal dysostosis are described and the literature reacting to this disorder is reviewed. Chromosomal analysis suggests that some cells with trisomy for chromosome 16 may be present in this patient. Therapy with massive doses of vitamin D parenterally failed to influence the roentgenographic changes in the metaphyses.