ABSTRACT
The protective effects of novel synthesized derivatives of some amino acids — nicotinyl-L-tyrosinate and nicotinyl-L-tryptophanate schiff bases and their Cu(II) and Mn(II) chelates on growth, survival and membrane-associated ATPase activity of E. coli under X-ray irradiation were investigated. The specific growth rate and survival of E. coli were decreased at 10, 20 and 30 Gy doses. However, as 30 Gy was found to be the most effective irradiation dose, it was chosen for studying the radio-protective properties of different compounds. These compounds could increase the bacterial cell protection against X-ray irradiation in concentration-dependent manner. They had a role in stimulation of synthesis or regulation of activity of metal-dependent enzymes, required for reversing the X-ray irradiation damage. The study may prove useful for further estimation of the effectiveness of different compounds as radio-protectors on bacteria and other cells, especially mammalian cells under X-ray irradiation.
Subject(s)
Adenosine Triphosphatases/metabolism , Amino Acids/chemical synthesis , Amino Acids/chemistry , Amino Acids/pharmacology , Cell Membrane/drug effects , Cell Membrane/enzymology , Cell Membrane/radiation effects , Chelating Agents/chemistry , Escherichia coli/cytology , Escherichia coli/drug effects , Escherichia coli/growth & development , Escherichia coli/radiation effects , Microbial Viability/drug effects , X-Rays/adverse effectsABSTRACT
A common side effect of radiotherapy used in the treatment of oral cancer is the occurrence of structural and physiological alterations of the salivary glands due to exposure to ionizing radiation, as demonstrated by conditions such as decreased salivary flow. The present study evaluated ultrastructural alterations in the parotid glands of rats receiving a fractionated dose (1,500-cGy) of radiation emitted by a Cesium-137 source and rats that were not subjected to ionizing radiation. After sacrifice, the parotid glands were removed and examined by transmission electron microscopy. Damage such as cytoplasmic vacuolization, dilatation of the endoplasmic reticulum and destruction of mitochondria, as well as damage to the cellular membrane of acinar cells, were observed. These findings lead to the conclusion that ionizing radiation promotes alterations in the glandular parenchyma, and that these alterations are directly related to the dose level of absorbed radiation. Certain phenomena that appear in the cytoplasm and nuclear material indicate that ionizing radiation causes acinar cell death (apoptosis).
Um efeito colateral comum da radioterapia usada no tratamento de câncer na cavidade oral é a ocorrência de alterações estruturais e fisiológicas sobre as glândulas salivares por exposição à radiação ionizante, como demonstrada em situações com decréscimo do fluxo salivar. O presente estudo teve por objetivo avaliar as alterações ultra-estruturais de glândulas parótidas de ratos que receberam uma dose fracionada (1500 - cGy) de radiação emitida por uma fonte de Césio 137 e ratos que não receberam a radiação ionizante. Após o sacrifício, as glândulas parótidas foram removidas e examinadas por microscopia eletrônica de transmissão. Lesões das organelas citoplasmáticas, como dilatação do retículo endoplasmático, destruição das mitocôndrias e formação das vacuolizações citoplasmáticas, além de lesão da membrana celular das células acinares foram observadas. Portanto, a radiação ionizante promove alterações no parênquima glandular, o que está diretamente relacionado com a dose de radiação absorvida. Determinados fenômenos que surgem no citoplasma e material nuclear são indicadores de que a radiação ionizante leva a célula acinar a morte programada (apoptose).