The effect of low-level laser therapy on oxidative stress and functional fitness in aged rats subjected to swimming: an aerobic exercise.

The aim of the present study was to determine whether low-level laser therapy (LLLT) in conjunction with aerobic training interferes with oxidative stress, thereby influencing the performance of old rats participating in swimming. Thirty Wistar rats (Norvegicus albinus) (24 aged and six young) were tested. The older animals were randomly divided into aged-control, aged-exercise, aged-LLLT, aged-LLLT/exercise, and young-control. Aerobic capacity (VO2max(0.75)) was analyzed before and after the training period. The exercise groups were trained for 6 weeks, and the LLLT was applied at 808 nm and 4 J energy. The rats were euthanized, and muscle tissue was collected to analyze the index of lipid peroxidation thiobarbituric acid reactive substances (TBARS), glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) activities. VO2 (0.75)max values in the aged-LLLT/exercise group were significantly higher from those in the baseline older group (p <0.01) and the LLLT and exercise group (p <0.05). The results indicate that the activities of CAT, SOD, and GPx were higher and statistically significant (p <0.05) in the LLLT/exercise group than those in the LLLT and exercise groups. Young animals presented lesser and statistically significant activities of antioxidant enzymes compared to the aged group. The LLLT/exercise group and the LLLT and exercise group could also mitigate the concentration of TBARS (p > 0.05). Laser therapy in conjunction with aerobic training may reduce oxidative stress, as well as increase VO2 (0.75)max, indicating that an aerobic exercise such as swimming increases speed and improves performance in aged animals treated with LLLT.

Photo-damage, photo-protection and age-related macular degeneration.

Age-related macular degeneration (AMD) is a degenerative retinal disease that causes blindness in people 60-65 years and older, with the highest prevalence appearing in people 90 years-old or more. Epidemiological estimates indicate that the number of cases is increasing, and will almost double in the next 20 years. Preventive measures require precise etiological knowledge. This is quite difficult, since AMD is a multifactorial condition with intricate relationships between causes and risk factors. In this review, we describe the impact of light on the structure and physiology of the retina and the pigment epithelium, taking into account the continuous exposure to natural and artificial light sources along the life of an individual. A large body of experimental evidence demonstrates the toxic effects of some lighting conditions on the retina and the pigment epithelium, and consensus exists about the importance of photo-oxidation phenomena in the causality chain between light and retinal damage. Here, we analyzed the transmission of light to the retina, and compared the aging human macula in healthy and diseased retinas, as shown by histology and non-invasive imaging systems. Finally, we have compared the putative retinal photo-sensitive molecular structures that might be involved in the genesis of AMD. The relationship between these compounds and retinal damage supports the hypothesis of light as an important initiating cause of AMD.

p53 protein expression in skin with different levels of photoaging.

In non-melanoma skin cancer, keratinocytes show marked p53 protein expression. Considering photoaging as a background for skin cancer, p53 protein expression by immunohistochemistry was evaluated in normal skin with different levels of photoaging. The difference in p53 expression between mild and severe levels of photoaging was not statistically significant (P=0.169).

Avaliação do efeito da radiação x no crescimento mandibular de camundongos

Foi objetivo deste trabalho avaliar a ação da radiação X em doses baixas, desde uma idade precoce até a vida adulta analisando a sua ação nas células a partir do desenvolvimento mandibular. Foi realizado um estudo experimental utilizando 90 camundongos machos com 6 semanas de vida, tendo um grupo-controle(G1 - 40 animais), um grupo que foi exposto à radiação semanalmente por 30 semanas (G2 - 40 animais) e um grupo de 10 animais (Go) que foi utilizado para o estabelecimento das medidas mandibulares iniciais de controle. Ao términi do experimento as mandíbulas dos animais foram retiradas e dissecadas. Foram realizadas seis medidas mandibulares. A análise de variância múltipla considerando as 6 medidas como variáveis dependentes mostrou diferença estatística significativa para todas as medidas. Através dos resultados obtidos, pôde-se detectar a interferência da radiação X, causando a diminuição do crescimento ósseo em mandíbulas de camundongos durante o envelhecimento. Assim é possível concluir que existe associação entre exposição crônica à radiação X e redução no crescimento mandibular de camundongos.

Time course of the effects of prenatal gamma irradiation on the dorsal lateral geniculate nucleus of Swiss mice.

A previous study reported that adult mice irradiated at the 16th embryonic day present a severe neuronal number reduction in the dorsal lateral geniculate thalamic nucleus. In the present study, we investigated the time course of the effects of prenatal irradiation on this thalamic nucleus. One day after irradiation, a great number of pyknotic figures were seen mainly in the cerebral proliferative zones. In the geniculate nucleus, only scattered pyknotic figures were identified. On the first week after birth, the geniculate nucleus presented frequent pyknotic figures. From five days after birth onwards, a severe shrinkage of the occipital cortex and a great reduction in the geniculate nucleus neuronal number were found. On the second week after birth this neuronal number reduction reached as high as 75%. At each postnatal analyzed age, severe volumetric geniculate nucleus shrinkage was combined to non-significant neuronal density variations. The presence of few pyknotic figures in the geniculate nucleus one day after irradiation and its delayed neuronal loss indicate an indirect effect of irradiation. We suggest that the effect upon the geniculate nucleus is secondary to the damage of the occipital cortex. A possible interpretation for thalamic neuronal loss is that geniculate neurons fail to establish cortical arbors after major target loss. In this case, the loss of trophic support should also be considered.

Estudo comparativo das extensões das lesões causadas por duas e quatro passadas de laser Erbium em ratos Wistar com 0 por cento de sobreposição dos spots / Comparative study of extension of lesion caused by 2 and 4 erbium laser passes in Wistar rats with 0 percent overlap of spots

Lasers de CO2 tem sido apresentados com a finalidade de rejuvenecer a face através do resurfacing. Embora cada sistema de laser tenha o mesmo princípio básico, há significativa diferença entre os lasers que pode resultar em variações no efeito tecidual clínico e histológico. O laser Erbium:YAG que tem como característica o comprimento de onda com 10 vezes mais afinidade pela água que o laser de CO2. O propósito deste estudo experimental foi comparar as alterações morfométricas encontradas em 2 e 4 passadas com laser Erbium:YAG com sobreposição de 0 por cento dos spots. Foi avaliada a homogeneidade da ablaçãoem comprimento e usou-se a pele do dorso de 3 ratos in vivo. Foi selecionada uma área de pele controle de cada rato. Finalmente, num período máximo de 3 horas, a pele foi ressecada e encaminhada à histopatologia para as avaliações propostas. Como resultados com 4 passadas houve mais homogeneidade da extensão da ablação do que em 2 passadas. Conclui-se que a extensão e homogeneidade de ablação foi maior com 4 passadas. A utilização de 0 por cento de sobreposição dos spots não garante homogeneidade de ablação.

Alpha-amylase circadian rhythm of young rat parotid gland: an endogenous rhythm with maternal coordination.

The circadian rhythm of alpha-amylase, E.C. 3.2.1.1. alpha-1,4-glucan-4-glucanohydrolase) in the parotid glands of 25-day-old rats were studied under different experimental designs (fasting, reversed photoperiod, constant lighting conditions and treatment with reserpine and alpha-methyl-p-tyrosine). The rhythm of fasted rats did not change. There were modifications in the rhythm of rats submitted to a reversed photoperiod or treated with reserpine or alpha-methyl-p-tyrosine. The rhythm was present, with changes in the acrophase, in parotids of rats kept during their gestation and postnatal life in constant light or dark. Results suggest that the circadian rhythm of alpha-amylase in parotid gland of young rats is endogenous, synchronized by the photoperiod, and with maternal coordination.