Human prefrontal layer II interneurons in areas 46, 10 and 24 / Interneuronas de la lámina II en las áreas prefrontales 46, 10 y 24 del humano

Background: Prefrontal cortex (PFC) represents the highest level of integration and control of psychic and behavioral states. Several dysfunctions such as autism, hyperactivity disorders, depression, and schizophrenia have been related with alterations in the prefrontal cortex (PFC). Among the cortical layers of the PFC, layer II shows a particular vertical pattern of organization, the highest cell density and the biggest non-pyramidal/pyramidal neuronal ratio. We currently characterized the layer II cytoarchitecture in human areas 10, 24, and 46. Objective: We focused particularly on the inhibitory neurons taking into account that these cells are involved in sustained firing (SF) after stimuli disappearance. Methods: Postmortem samples from five subjects who died by causes different to central nervous system diseases were studied. Immunohistochemistry for the neuronal markers, NeuN, parvalbumin (PV), calbindin (CB), and calretinin (CR) were used. NeuN targeted the total neuronal population while the rest of the markers specifically the interneurons. Results: Cell density and soma size were statically different between areas 10, 46, 24 when using NeuN. Layer II of area 46 showed the highest cell density. Regarding interneurons, PV+-cells of area 46 showed the highest density and size, in accordance to the proposal of a dual origin of the cerebral cortex. Interhemispheric asymmetries were not identified between homologue areas. Conclusion: First, our findings suggest that layer II of area 46 exhibits the most powerful inhibitory system compared to the other prefrontal areas analyzed. This feature is not only characteristic of the PFC but also supports a particular role of layer II of area 46 in SF. Additionally, known functional asymmetries between hemispheres might not be supported by morphological asymmetries.

Antecedentes: La corteza prefrontal (CPF) representa el nivel más alto de integración y control de funciones psíquicas y comportamentales. Varias patologías como autismo, desórdenes de hiperactividad, depresión y esquizofrenia se han relacionado con alteraciones de la CPF. La lámina II de las áreas que constituyen la CPF posee un patrón de organización vertical, una alta densidad celular y la mayor proporción de neuronas no-piramidal/piramidal. Sin embargo, la distribución del componente inhibitorio en estas regiones no se ha descrito. Objetivo: En el presente estudio nos propusimos caracterizar la lámina II de las áreas 10, 24 y 46 del humano, particularmente su componente inhibitorio teniendo en mente su participación en procesos de actividad sostenida relevantes cuando desaparece el estímulo. Métodos: Se utilizaron muestras de cinco sujetos que fallecieron por causas diferentes a enfermedades del sistema nervioso. Se tomaron secciones de las áreas 10, 24 y 46 de Brodmann y se procesaron con los anticuerpos contra NeuN para determinar la población neuronal total y contra Parvalbumina (PV), Calbindina (CB) y Calretinina (CR) para analizar la población de interneuronas. Resultados: Los resultados no mostraron diferencias interhemisféricas entre las áreas. Sin embargo, las tres áreas seleccionadas son significativamente diferentes entre sí en todos los parámetros analizados. El área 46 posee la mayor densidad y tamaño de interneuronas positivas para PV. Conclusiones: La ausencia de asimetrías morfológicas no permite explicar las asimetrías funcionales. La lámina II del área 46 posee el sistema inhibitorio más poderoso. Teniendo en cuenta la arquitectura modular de las capas supragranulares, este sistema inhibitorio subyace a la actividad sostenida, eje fundamental de la memoria operativa.

Prevention of CCL[4]-induced oxidative damage in adrenal gland by digera murica ta extract in rat

Digera muricata [L.] Mart, is a weed and commonly found in waste places, road sides and in maize fields during the summer season. It possesses antioxidant capacity and is locally used for various disorders such as inflammation, urination, as refrigerant, aperient and in sexual anomalies. In this study antioxidant potential of Digera muricata methanol extract [DMME] and n-hexane extract [DMHE] was evaluated against CCl[4]-induced oxidative stress in adrenal gland of Sprague-Dawley male rats. 42 rats were equally divided into 7 groups of 6 rats in each. Group I remained untreated, while Group II treated with vehicles. Group III received only CC1[4] [1 ml/kg b.w., 10% in olive oil] once a week for 16 weeks. Group IV and VI received DMME and DMHE at a dose of 200 mg/kg b.w. along with CC1[4]. Animals of Group V and VII administered with DMME and DMHE alone at a dose of 200 mg/kg b.w. once a week for 16 weeks. Lipid peroxidation significantly increased while activities of antioxidant enzymes [CAT, SOD, GST, GSR and GSH-Px] were reduced in adrenal gland samples by the administration of CC14. Glutathione [GSH] concentration was significantly decreased whereas DNA fragmentation% and AgNORs count was increased in adrenal gland by CC1[4] administration. Treatment of rat by both the extracts [DMME, DMHE] and CC1[4] increased the glutathione level and activities of antioxidant enzymes while reduced the lipid peroxidation, DNA fragmentation percent and AgNORs count in adrenal gland. These results indicate that Digera muricata extract is able to ameliorate oxidative stress in adrenal gland induced by CC1[4] in rat

Immunohistochemical expression of markers Ki-67, neun, synaptophysin, p53 and HER2 in medulloblastoma and its correlation with clinicopathological parameters / Expressão imunoistoquímica dos marcadores Ki-67, neun, sinaptofisina, p53 e HER2 em meduloblastoma e sua correlação com os parâmetros clínico-patológicos

Medulloblastoma (MB) is the most common malignant brain tumor in childhood. The alterations found include: presence of oncoproteins p53 and HER2, elevated mitotic index, and presence of neuronal differentiation. The aim of this study was to determine the immunohistochemical expression of markers Ki-67, NeuN, synaptophysin, HER2 and p53 in 40 MB samples and their correlation with clinicopathologic parameters and survival. In 29 patients (72.5 percent), >20 percent of cells were positive for Ki-67. Males showed greater ki-67 expression (p=0.02) and smaller survival rates (p=0.002). NeuN and synaptophysin were negative in 16 (40 percent) and 8 (20 percent) cases, respectively. P53 was positive in 18 (45 percent) cases, with 11 (61 percent) weakly positive and 7 (39 percent) strongly positive. HER2 was positive in 23 (57.5 percent) of the samples and did not show statistical association with survival (p=0.07).

Meduloblastoma (MB) é o tumor maligno encefálico mais freqüente na infância. dentre as alterações encontradas estão: a presença das oncoproteínas p53 e HER2, elevado índice mitótico e presença de diferenciação neuronal. o objetivo deste estudo foi determinar a expressão imunoistoquímica (IMQ) dos marcadores Ki-67, NeuN, sinaptofisina, HER2 e p53 em 40 amostras de MB, correlacionando-as com parâmetros clinicopatológicos e com a sobrevida. Vinte e nove pacientes (72,5 por cento) apresentaram 20 por cento ou mais das células positivas para Ki-67. os pacientes do sexo masculino apresentaram maior expressão do Ki-67 (p=0,02) e também menor sobrevida (p=0,002). NeuN e sinaptofisina foram negativos em 16 (40 por cento) e 8 (20 por cento) casos, respectivamente. P53 foi positivo em 18 (45 por cento) casos, sendo 11 (61 por cento) fracamente positivos e 7 (39 por cento) fortemente positivos. HER2 foi positivo em 23 (57,5 por cento) das amostras e não demonstrou associação estatística com a sobrevida (p=0.07).

SIRT1 promotes DNA repair activity and deacetylation of Ku70

Human SIRT1 controls various physiological responses including cell fate, stress, and aging, through deacetylation of its specific substrate protein. In processing DNA damage signaling, SIRT1 attenuates a cellular apoptotic response by deacetylation of p53 tumor suppressor. The present study shows that, upon exposure to radiation, SIRT1 could enhance DNA repair capacity and deacetylation of repair protein Ku70. Ectopically over-expressed SIRT1 resulted in the increase of repair of DNA strand breakages produced by radiation. On the other hand, repression of endogenous SIRT1 expression by SIRT1 siRNA led to the decrease of this repair activity, indicating that SIRT1 can regulate DNA repair capacity of cells with DNA strand breaks. In addition, we found that SIRT1 physically complexed with repair protein Ku70, leading to subsequent deacetylation. The dominant-negative SIRT1, a catalytically inactive form, did not induce deacetylation of Ku70 protein as well as increase of DNA repair capacity. These observations suggest that SIRT1 modulates DNA repair activity, which could be regulated by the acetylation status of repair protein Ku70 following DNA damage.

Usefulness of argyrophilic nucleolar organizer regions in detection of lung cells alterations after benzo[a]pyrene instillation

PURPOSE: To verify the relationship between AgNOR expression and lung tissues changes of Wistar rats after pulmonary instillation of benzo[a]pyrene (B[a]P). METHODS: Male Rattus norvegicus albinus,Wistar lineage were given a single intrapulmonary instillation of B[a]P at doses of 10 and 20 mg/kg in a volume of approximately 0,3 ml. After 7 and 21 days the rats were killed and the lung slices submitted to a histological technique of AgNOR. AgNOR dots were quantified and the result analyzed by statistical tests; p <= 0,05 was considered significant. RESULTS: The mean values of AgNOR dots for the experimental groups 10/7 (1,51±0,86) and 10/21 (1,84±0,13) were statistically different (p = 0,009). Among the groups 20/7 (1,63±0,11) and 20/21 (2,48±0,28) was observed statistically significant difference (p = 0,003). CONCLUSION: The AgNOR technique can be useful in identification of cells changes induced by B[a]P.

OBJETIVO: Verificar a relação entre a expressão de AgNOR e alterações teciduais pulmonares em ratos Wistar após instilação pulmonar de benzo[a]pireno (B[a]P). MÉTODOS: Rattus norvegicus albinus, linhagem Wistar machos foram submetidos à instilação pulmonar única de B[a]P em doses de 10 e 20mg/kg, em um volume aproximado de 0,3 ml. Os animais foram sacrificados após 7 e 21 dias e o tecido pulmonar submetido a técnica histológica de AgNOR. Os pontos AgNOR foram quantificados e os resultados analisados estatisticamente; foram considerados significantes os valores de p <= 0,05. RESULTADOS: Os valores médios de pontos AgNOR no grupo experimental 10/7 (1,51±0,86) e 10/21 (1,84±0,13) foram estatisticamente significantes (p = 0,009). Entre os grupos 20/7 (1,63±0,11) e 20/21 (2,48±0,28) a diferença observada foi também considerada significante (p = 0,003). CONCLUSÃO: A técnica de AgNOR pode ser útil na identificação de alterações celulares induzidas pelo B[a]P.

Decreased expression of DNA repair proteins Ku70 and Mre11 is associated with aging and may contribute to the cellular senescence

The gradual loss of telomeric DNA can contribute to replicative senescence and thus, having longer telomeric DNA is generally considered to provide a longer lifespan. Maintenance and stabilization of telomeric DNA is assisted by binding of multiple DNA-binding proteins, including those involved in double strand break (DSB) repair. We reasoned that declining DSB repair capacity and increased telomere shortening in aged individuals may be associated with decreased expression of DSB repair proteins capable of telomere binding. Our data presented here show that among the DSB repair proteins tested, only the expression of Ku70 and Mre11 showed statistically significant age-dependent changes in human lymphocytes. Furthermore, we found that expressions of Ku70 and Mre11 are statistically correlated, which indicate that the function of Ku70 and Mre11 may be related. All the other DSB repair proteins tested, Sir2, TRF1 and Ku80, did not show any significant differences upon aging. In line with these data, people who live in the regional community (longevity group), which was found to have statistically longer average life span than the rest area, shows higher level of Ku70 expression than those living in the neighboring control community. Taken together, our data show, for the first time, that Ku70 and Mre11 may represent new biomarkers for aging and further suggest that maintenance of higher expression of Ku70 and Mre11 may be responsible for keeping longer life span observed in the longevity group.