Involvement of K+ATP and Ca2+ channels in hydrogen sulfide-suppressed ageing of porcine oocytes

BACKGROUND: Hydrogen sulfide has been shown to improve the quality of oocytes destined for in vitro fertilization. Although hydrogen sulfide is capable of modulating ion channel activity in somatic cells, the role of hydrogen sulfide in gametes and embryos remains unknown. Our observations confirmed the hypothesis that the KATP and L-type Ca2+ ion channels play roles in porcine oocyte ageing and revealed a plausible contribution of hydrogen sulfide to the modulation of ion channel activity. RESULTS: We confirmed the benefits of the activation and suppression of the KATP and L-type Ca2+ ion channels, respectively, for the preservation of oocyte quality. CONCLUSIONS: Our experiments identified hydrogen sulfide as promoting the desired ion channel activity, with the capacity to protect porcine oocytes against cell death. Further experiments are needed to determine the exact mechanism of hydrogen sulfide in gametes and embryos.

Conserved genes and pathways in primary human fibroblast strains undergoing replicative and radiation induced senescence

BACKGROUND: Cellular senescence is induced either internally, for example by replication exhaustion and cell division, or externally, for example by irradiation. In both cases, cellular damages accumulate which, if not successfully repaired, can result in senescence induction. Recently, we determined the transcriptional changes combined with the transition into replicative senescence in primary human fibroblast strains. Here, by γ-irradiation we induced premature cellular senescence in the fibroblast cell strains (HFF and MRC-5) and determined the corresponding transcriptional changes by high-throughput RNA sequencing. RESULTS: Comparing the transcriptomes, we found a high degree of similarity in differential gene expression in replicative as well as in irradiation induced senescence for both cell strains suggesting, in each cell strain, a common cellular response to error accumulation. On the functional pathway level, "Cell cycle" was the only pathway commonly down-regulated in replicative and irradiation-induced senescence in both fibroblast strains, confirming the tight link between DNA repair and cell cycle regulation. However, "DNA repair" and "replication" pathways were down-regulated more strongly in fibroblasts undergoing replicative exhaustion. We also retrieved genes and pathways in each of the cell strains specific for irradiation induced senescence. CONCLUSION: We found the pathways associated with "DNA repair" and "replication" less stringently regulated in irradiation induced compared to replicative senescence. The strong regulation of these pathways in replicative senescence highlights the importance of replication errors for its induction.

The Role of Foxo3 in Leydig Cells

PURPOSE: Foxo3 in female reproduction has been reported to regulate proliferation of granulose cells that form follicles. There are no reports so far that discuss on the role of Foxo3 in males. This study was designed to outline the role of Foxo3 in the testes. MATERIALS AND METHODS: Testes from mice at birth to postpartum week (PPW) 5 were isolated and examined for the expression of Foxo3 using immunostaining. To elucidate role of Foxo3 in Leydig cells, R2C cells were treated with luteinizing hormone (LH) and the phosphorylation of Foxo3. Testosterone and steroidogenic acute regulatory (StAR) protein levels were measured after constitutive active [triple mutant (TM)] human FOXO3 adenovirus was transduced and StAR promoter assay was performed. RESULTS: Foxo3 expression in the testicles started from birth and lasted until PPW 3. After PPW 3, most Foxo3 expression occurred in the nuclei of Leydig cells; however, at PPW 5, Foxo3 was expressed in both the nucleus and cytoplasm. When R2C cells were treated with luteinizing hormone, Foxo3 phosphorylation levels by AKT increased. After blocking the PI3K pathway, LH-induced phosphorylated Foxo3 levels decreased, indicating that LH signaling regulates Foxo3 localization. When active FOXO3-TM adenovirus was introduced into a Leydig tumor cell line, the concentrations of testosterone and StAR protein decreased. When FOXO3 and a StAR promoter vector were co-transfected into HEK293 cells for a reporter assay, FOXO3 inhibited the StAR promoter. CONCLUSION: FOXO3 affects testosterone synthesis by inhibiting the formation of StAR protein. LH hormone, meanwhile, influences Foxo3 localization, mediating its function.

Inquérito Brasileiro de Diálise Crônica 2013 - Análise das tendências entre 2011 e 2013 / Brazilian Chronic Dialysis Survey 2013 - Trend analysis between 2011 and 2013

Introdução: Dados nacionais sobre diálise crônica têm tido impacto no planejamento do tratamento. Objetivo: Apresentar dados do inquérito da Sociedade Brasileira de Nefrologia sobre os pacientes com doença renal crônica em tratamento dialítico em julho de 2013 e comparar com dados de 2011- 12. Métodos: Levantamento de dados de unidades de diálise do país. A coleta de dados foi feita utilizando questionário preenchido on-line pelas unidades de diálise. Resultados: Trezentos e trinta e quatro (51%) unidades responderam ao inquérito. Em julho de 2013, o número total estimado de pacientes em diálise foi de 100.397. As estimativas nacionais das taxas de prevalência e de incidência de tratamento dialítico foram de 499 (variação: 284 na região Norte e 622 na Sul) e 170 pacientes por milhão da população, respectivamente. O número estimado de pacientes que iniciaram tratamento em 2013 foi 34.161. A taxa anual de mortalidade bruta foi de 17,9%. Dos pacientes prevalentes, 31,4% tinham idade ≥ 65 anos, 90,8% estavam em hemodiálise e 9,2% em diálise peritoneal, 31.351 (31,2%) estavam em fila de espera para transplante, 30% tinham diabetes, 17% tinham PTH > 600 pg/ml e 23% hemoglobina < 10 g/dl. Cateter venoso era usado como acesso em 15,4% dos pacientes em hemodiálise. Conclusão: O número absoluto de pacientes em diálise tem aumentado 3% ao ano nos últimos 3 anos. As taxas de prevalência e incidência de pacientes em diálise ficaram estáveis, e a taxa de mortalidade tendeu a diminuir em relação a 2012. Houve tendência a melhor controle da anemia e dos níveis de PTH. .

Introduction: National chronic dialysis data have had impact in the treatment planning. Objective: To report data of the annual survey of the Brazilian Society of Nephrology about chronic kidney disease patients on dialysis in July 2013 and compare with 2011-12. Methods: A survey based on data of dialysis units from the whole country. The data collection was performed by using a questionnaire filled out on-line by the dialysis units. Results: Three hundred thirty four (51%) of the dialysis units in the country answered the questionnaire. In July 2013, the total estimated number of patients on dialysis was 100,397. The estimated prevalence and incidence rates of chronic maintenance dialysis were 449 (range: 284 in the North region and 622 in the South) and 170 patients per million population, respectively. The estimated number of new patients starting dialysis in 2013 was 34,161. The annual gross mortality rate was 17.9%. For prevalent patients, 31.4% were aged 65 years or older, 90.8% were on hemodialysis and 9.2% on peritoneal dialysis, 31,351 (31.2%) were on a waiting list of renal transplant, 30% were diabetics, 17% had PTH levels > 600 pg/ml and 23% hemoglobin < 10 g/ dl. A venous catheter was the vascular access for 15.4% of the hemodialysis patients. Conclusion: The absolute number of patients on dialysis has increased 3% per year. The prevalence and incidence rates of patients on dialysis leveled off, while the mortality rate tended to decrease compared with 2012. There was a trend towards a better control of the anemia and PTH levels. .

Mixed Periapical Lesion: An Atypical Radicular Cyst with Extensive Calcifications

The radicular cyst is an inflammatory odontogenic cyst of endodontic origin. Radiographically, the lesion appears as a periapical radiolucent image. This report describes a very rare case of a mixed periapical radiographic image diagnosed as a radicular cyst. A 37-year-old female patient presented a mixed, well-circumscribed image located in the periapical region of the left maxillary central incisor, which presented unsatisfactory endodontic treatment. Microscopic examination revealed a cavity lined by non-keratinized squamous epithelium and extensive calcifications in the cystic lumen and lining epithelium. Diagnosis of radicular cyst with extensive calcifications was established. Endodontic retreatment was performed and no radiographic signs of recurrence were observed 18 months after treatment. Although very rare, a radicular cyst should be considered in the differential diagnosis of a mixed periapical image associated to teeth with pulp necrosis.

O cisto radicular é um cisto odontogênico inflamatório de origem endodôntica. Radiograficamente, a lesão se apresenta como uma imagem radiolúcida periapical. Este relato descreve um caso muito raro de uma imagem radiográfica periapical mista diagnosticada como cisto radicular. Uma paciente de 37 anos de idade, do gênero feminino, apresentava uma imagem mista, bem circunscrita, localizada na região periapical do incisivo central superior esquerdo, que apresentava tratamento endodôntico insatisfatório. Avaliação microscópica revelou uma cavidade revestida por epitélio escamoso não-queratinizado e calcificações extensas na cavidade cística e revestimento epitelial. O diagnóstico de cisto radicular com extensas calcificações foi estabelecido. Retratamento endodôntico foi realizado e não foram observados sinais radiográficos de recorrência da lesão após 18 meses de tratamento. Embora muito raro, um cisto radicular deve ser considerado no diagnóstico diferencial de uma imagem periapical mista associada a dentes com necrose pulpar.

Avaliação do fenótipo e da proliferação celular das estruturas ductiformes no processo de envelhecimento de glândulas sublinguais humanas / Evaluation of the phenotype and the proliferation capacity of duct-like structures in the aging process of human sublingual glands

São várias as alterações microscópicas decorrentes do processo de envelhecimento das glândulas salivares, dentre elas o aumento no número de estruturas ductiformes. O objetivo deste trabalho é estudar o fenótipo e o índice de proliferação celular das mesmas. Sessenta glândulas sublinguais de cadáveres humanos foram divididas em dois grupos segundo a aixa etária dos indivíduos (0-30 anos e 61-90 anos). O fenótipo foi estimado pela imunomarcação da citoqueratina 19 (CK 19), da proteína S-100 e pela evidenciação dos polissacarídeos mucina e glicogênio. A avaliação do índice de proliferação de células epiteliais das estruturas ductiformes se deu por meio da imunomarcação do Ki-67. As técnicas histoquímicas consistiram no ácido periódico de Schiff (PAS) e Azul de Alcian pH 2,5. Em cada campo microscópico capturado foram contadas as estruturas ductiformes para estabelecer o perfil de marcação em percentual. A análise estatística foi realizada por meio dos testes t de Student, Mann-Whitney e correlação de Pearson (p < 0,05). Comparando os dois grupos, apenas a imunomarcação para CK 19 mostrou diferença estatisticamente significante (p = 0,033), sendo sua expressão mais forte no grupo de idosos. Não houve diferença significante entre os marcadores PAS e Azul de Alcian (p = 0,270). Nos dois grupos a imunomarcação para CK 19 foi mais forte do que para S-100 (p = 0,004; p < 0,001), sendo a correlação entre os dois imunomarcadores ausente (ρ = -0,163; p = 0,315). Não houve imunomarcação para o Ki-67 em nenhuma estrutura ductiforme. Concluiu-se que as estruturas ductiformes demonstram um perfil fenotípico ductal e não apresentam atividade proliferativa celular. Elas podem representar um processo regressivo com origem nos ácinos ou resultarem de metaplasia.

There are several age-related microscopic changes in the salivary glands, including the increase in the number of duct-like structures. The aim of this study is to evaluate the phenotype and the cell proliferation index of these structures. Sixty sublingual glands obtained from human cadavers were divided into two groups according to the individuals age (0-30 and 61-90 years old). The phenotype was estimated by the immunostaining for cytokeratin 19 (CK 19), S-100 protein and by the disclosure of the polysaccharides mucin and glycogen. The cell proliferation index was determined by Ki-67 immunostaining. The histochemical techniques consisted of periodic acid-Schiff (PAS) and Alcian Blue pH 2.5. Ineach captured microscopic field, the duct-like structures were counted to establish the staining profile in percentage. Statistical analysis was done by Students t-test, Mann-Whitney test and Pearsons correlation coefficient (p < 0.05). Comparing the two groups, only the immunostaining for CK 19 showed significant statistical difference (p = 0.033), with strongest expression in the elderly group. There was no significant difference between the markers PAS and Alcian Blue (p = 0.270). In both groups the immunostaining for CK 19 was stronger than for S-100 (p = 0.004; p < 0.001), but there was no correlation between the two immunomarkers (ρ = -0.163; p = 0.315). There was no immunostaining for Ki-67 in any ductlike structure. We concluded that the duct-like structures demonstrate a ductal phenotypic profile and do not present cell proliferation activity. They may represent a regressive process arising from acini or a result of a metaplasia.

Avaliação do fenótipo e da proliferação celular das estruturas ductiformes no processo de envelhecimento de glândulas sublinguais humanas / Evaluation of the phenotype and the proliferation capacity of duct-like structures in the aging process of human sublingual glands

São várias as alterações microscópicas decorrentes do processo de envelhecimento das glândulas salivares, dentre elas o aumento no número de estruturas ductiformes. O objetivo deste trabalho é estudar o fenótipo e o índice de proliferação celular das mesmas. Sessenta glândulas sublinguais de cadáveres humanos foram divididas em dois grupos segundo a aixa etária dos indivíduos (0-30 anos e 61-90 anos). O fenótipo foi estimado pela imunomarcação da citoqueratina 19 (CK 19), da proteína S-100 e pela evidenciação dos polissacarídeos mucina e glicogênio. A avaliação do índice de proliferação de células epiteliais das estruturas ductiformes se deu por meio da imunomarcação do Ki-67. As técnicas histoquímicas consistiram no ácido periódico de Schiff (PAS) e Azul de Alcian pH 2,5. Em cada campo microscópico capturado foram contadas as estruturas ductiformes para estabelecer o perfil de marcação em percentual. A análise estatística foi realizada por meio dos testes t de Student, Mann-Whitney e correlação de Pearson (p < 0,05). Comparando os dois grupos, apenas a imunomarcação para CK 19 mostrou diferença estatisticamente significante (p = 0,033), sendo sua expressão mais forte no grupo de idosos. Não houve diferença significante entre os marcadores PAS e Azul de Alcian (p = 0,270). Nos dois grupos a imunomarcação para CK 19 foi mais forte do que para S-100 (p = 0,004; p < 0,001), sendo a correlação entre os dois imunomarcadores ausente (ρ = -0,163; p = 0,315). Não houve imunomarcação para o Ki-67 em nenhuma estrutura ductiforme. Concluiu-se que as estruturas ductiformes demonstram um perfil fenotípico ductal e não apresentam atividade proliferativa celular. Elas podem representar um processo regressivo com origem nos ácinos ou resultarem de metaplasia.

There are several age-related microscopic changes in the salivary glands, including the increase in the number of duct-like structures. The aim of this study is to evaluate the phenotype and the cell proliferation index of these structures. Sixty sublingual glands obtained from human cadavers were divided into two groups according to the individuals age (0-30 and 61-90 years old). The phenotype was estimated by the immunostaining for cytokeratin 19 (CK 19), S-100 protein and by the disclosure of the polysaccharides mucin and glycogen. The cell proliferation index was determined by Ki-67 immunostaining. The histochemical techniques consisted of periodic acid-Schiff (PAS) and Alcian Blue pH 2.5. Ineach captured microscopic field, the duct-like structures were counted to establish the staining profile in percentage. Statistical analysis was done by Students t-test, Mann-Whitney test and Pearsons correlation coefficient (p < 0.05). Comparing the two groups, only the immunostaining for CK 19 showed significant statistical difference (p = 0.033), with strongest expression in the elderly group. There was no significant difference between the markers PAS and Alcian Blue (p = 0.270). In both groups the immunostaining for CK 19 was stronger than for S-100 (p = 0.004; p < 0.001), but there was no correlation between the two immunomarkers (ρ = -0.163; p = 0.315). There was no immunostaining for Ki-67 in any ductlike structure. We concluded that the duct-like structures demonstrate a ductal phenotypic profile and do not present cell proliferation activity. They may represent a regressive process arising from acini or a result of a metaplasia.

Estudio del envejecimiento con un modelo celular del síndrome de progeria de Hutchinson-Gilford / Study of the agening with a cellular model of Hutchinson-Gilford progeria syndrome

Se presenta en forma resumida los principales hallazgos del trabajo de Liu y col (1), investigadores del Instituto Salk, California, publicado en abril de 2011, donde se describe un modelo celular in vitro del síndrome de progeria de Hutchison-Gilford (SPHG), basado en células madre pluripotentes inducidas po reprogramación de fibroblastos. Tiene gran interés porque ofrece la posibilidad de estudiar la fisiopatología de las enfermedades que cursan con envejecimiento rápido, prematuro y ayudar a compreder mejor los procesos de envejecimiento que ocurren en la población humana general. Se incluye información básica relacionada con la progeria

A summary of the main findings published in April 2011 by Liu et al (1), researchers at the Salk Institute, California, where a cellular in vitro model of Hutchinson-Gilford progeria syndrome (HGPS) was described based on induced pluripotent stem cells derived from reprogrammed fibroblasts. It is of great interest because it allows the study of the pathogenesis of premature, rapid aging and helps understand ageing of the general human population. Basic information about progeria is included

Aspectos fisiológicos do cálcio e sua disfunção em patologias neurodegenerativas / Physiological aspects of calcium and its dysfunction in neurodegenerative diseases

O íon cálcio funciona como um segundo mensageiro que regula um amplo espectro de processos celulares. A diminuição ou perda do controle dos mecanismos que regulam a concentração intracelular desse íon está associada, respectivamente, ao envelhecimento dos neurônios e a doenças neurodegenerativas. A gênese dessas modificações é desconhecida. Entretanto, estudos recentes apontam para uma provável correlação entre expressão gênica alterada, estresse do retículo endoplasmático e os processos patológicos associados à disfunção na concentração intracelular de cálcio. O esclarecimento dessas questões poderá trazer novos alvos terapêuticos capazes de frear ou reverter tais alterações, combatendo, dessa forma, tanto o envelhecimento neuronal quanto as doenças neurodegenerativas.

Calcium is a second messenger that regulates a lot of cellular functions. The following mechanisms regulate the intracellular concentrations of the ion: influx, release, extrusion and storage. Decrease or loss in control of these mechanisms is related to aging of neurons and neurodegenerative diseases, respectively. The genesis of these alterations is unknown. However, recent studies point to a correlation between calcium dysfunction and altered gene expression. There is also a correlation between endoplasmic reticulum stress and pathological processes. Further investigations may reveal new therapeutical targets that can block or revert these alterations.

Testosterone therapy delays cardiomyocyte aging via an androgen receptor-independent pathway

The testicular feminized (Tfm) mouse carries a nonfunctional androgen receptor (AR) and reduced circulating testosterone levels. We used Tfm and castrated mice to determine whether testosterone modulates markers of aging in cardiomyocytes via its classic AR-dependent pathway or conversion to estradiol. Male littermates and Tfm mice were divided into 6 experimental groups. Castrated littermates (group 1) and sham-operated Tfm mice (group 2, N = 8 each) received testosterone. Sham-operated Tfm mice received testosterone in combination with the aromatase inhibitor anastrazole (group 3, N = 7). Castrated littermates (group 4) and sham-operated untreated Tfm mice (group 5) were used as controls (N = 8 and 7, respectively). An additional control group (group 6) consisted of age-matched non-castrated littermates (N = 8). Cardiomyocytes were isolated from the left ventricle, telomere length was measured by quantitative PCR and expression of p16INK4α, retinoblastoma (Rb) and p53 proteins was detected by Western blot 3 months after treatment. Compared with group 6, telomere length was short (P < 0.01) and expression of p16INK4α, Rb and p53 proteins was significantly (P < 0.05) up-regulated in groups 4 and 5. These changes were improved to nearly normal levels in groups 1 and 2 (telomere length = 0.78 ± 0.05 and 0.80 ± 0.08; p16INK4α = 0.13 ± 0.03 and 0.15 ± 0.04; Rb = 0.45 ± 0.05 and 0.39 ± 0.06; p53 = 0.16 ± 0.04 and 0.13 ± 0.03), but did not differ between these two groups. These improvements were partly inhibited in group 3 compared with group 2 (telomere length = 0.65 ± 0.08 vs 0.80 ± 0.08, P = 0.021; p16INK4α = 0.28 ± 0.05 vs 0.15 ± 0.04, P = 0.047; Rb = 0.60 ± 0.06 vs 0.39 ± 0.06, P < 0.01; p53 = 0.34 ± 0.06 vs 0.13 ± 0.03, P = 0.004). In conclusion, testosterone deficiency contributes to cardiomyocyte aging. Physiological testosterone can delay cardiomyocyte aging via an AR-independent pathway and in part by conversion to estradiol.

Morphoquantitative study of the submucous plexus (of Meissner) of the jejunum-ileum of young and old guinea pigs / Estudo morfoquantitativo do plexo submucoso (de Meissner) do jejuno-íleo de cobaias jovens e velhas

OBJECTIVE: To study the aging of submucous plexus of the small intestine (jejunum-ileum) of the guinea pigs from the quantitative, structural and ultrastructural perspective. METHOD: Chemical preparations of membrane of the jejunum-ileum of old and young animals with the use of light and electronic microscope. RESULTS: The ganglia of young animals presented between 1 and 56 neurons and the old animals presented from 1 to 30 neurons. The mean density of the ganglia by cm² in the young jejunum-ileum was of 551±36.89 and in the old one 413±11.86. The density of the neurons was 5011±291.11 neurons/cm² average in young animals and 2918±120.70 neurons/cm² in the old ones. The size of the neurons varied in both age groups. The collagen fibers in the ganglia of old animals they were condensed. Degenerated mitochondrias in the interior of the cell were frequent in the old animals. CONCLUSION: In submucous plexus of the jejunum-ileum there is a loss of 38 percent of the neurons with aging.

OBJETIVO: Estudar o envelhecimento do plexo submucoso do intestino delgado (jejuno-íleo) das cobaias do ponto de vista quantitativo, estrutural e ultra-estrutural. MÉTODO: Preparados de membrana do jejuno-íleo de animais jovens e velhos com a utilização de microscopia de luz e eletrônica. RESULTADOS: Os gânglios de animais jovens apresentaram entre 1 e 56 neurônios e os animais velhos apresentaram de 1 a 30 neurônios. A densidade média dos gânglios por cm² no jejuno-íleo jovem foi de 551±36,89 e no velho foi de 413±11,86. A densidade dos neurônios foi de 5011±291,11 neurônios/cm² em média nos animais jovens e 2918±120,70 neurônios/cm² nos velhos. O tamanho dos neurônios variou em ambos os grupos etários. As fibras colágenas nos gânglios de animais velhos estavam mais condensadas. Mitocôndrias degeneradas no interior da célula foram freqüentes nos animais velhos. CONCLUSÃO: No plexo submucoso do jejuno-íleo há uma perda de 38 por cento dos neurônios com o envelhecimento.

Introdução ao estudo do envelhecimento e suas principais teorias / Introduction to the study of aging and its main theories

Com a evolução da Medicina, nos últimos séculos, a expectatividade vida aumentou e, consequentemente, a população "envelheceu". Há pelo menos 600 milhões de idosos no mundo, e somente a partir do século XX o estudo do envelhecimento tomou maiores proporções. Foi empregada uma classificação simples e dual para explicar o processo do envelhecimento, subdividindo as teorias biológicas em estocásticas e sistêmicas. Se os efeitos postulados por determinada teoria acontecerem acidentalmente, ela será denominada teoria estocástica, mas se possuírem uma base genética e sofrerem interferência do meio ambiente, ela será denominada teoria sistêmica.

With the evolution of Medicine over the centuries, there was an increase in life expectancy and therefore the population "aged" for at least 600 million elderly people in the world and only from the 20h century that the study of aging has greater proportions. A simple dual classification was used to explain the aging process, subdividing the biological theories of stochastic and systemic. If the effects postulated by each theory happen accidentally, it will be called stochastic theory or if they have a genetic basis and suffer interference from the environment, they are systemic.

The dual role of senescence in tumorigenesis / Papel dual de la senescencia en la tumorigénesis

Senescence was rendered a tumor suppressor mechanism based on the observation of its protective effect against cancer in young organisms under conditions of oncogene activation or inactivation of tumor suppressor genes. In addition to this beneficial effect, senescence has been deemed to have age-associated deleterious effects because, apparently, senescence not only recapitulates aging and therefore loss of function and tissue regeneration capacity, but can also induce preneoplastic changes in adjacent stromal cells, provoke degenerative diseases or induce the production of tumor cell growth promoting factors. For that reason, senescence has become an attractive therapeutic target against cancer. This paper reviews some of the latest findings on the role of senescence in the malignant progression and analyzes them in relation to the concept of antagonistic pleiotropism, as well as its possible use as a therapeutic target against cancer.

La relación entre senescencia y transformación maligna ha sido objeto de particular atención, debido a una aparente dualidad de funciones, en la que la senescencia participaría tanto en la inducción como en la inhibición de la malignidad. El objetivo del trabajo fue revisar algunos de los hallazgos más recientes sobre el papel de la senescencia en la progresión maligna y analizarlos a la luz del concepto de la pleiotropía antagónica y de su posible utilización como blanco terapéutico contra el cáncer. Se considera a la senescencia como un mecanismo supresor tumoral, debido al efecto protector contra el cáncer que ejerce en organismos jóvenes, en caso de activación de oncogenes o de inactivación de genes supresores tumorales. Además de este efecto beneficioso, se le han adjudicado efectos deletéreos asociados con la edad pues, en apariencia, la senescencia no sólo recapitula el envejecimiento y por tanto la pérdida de función y capacidad de regeneración tisular, sino también puede inducir cambios preneoplásicos en las células del estroma adyacente, provocar enfermedades degenerativas o inducir la secreción de factores promotores del crecimiento de células tumorales. La aparición de defectos en el programa de senescencia puede contribuir a la transformación tumoral, lo que la ha convertido en un atractivo blanco terapéutico contra el cáncer. El avance en el estudio de los aspectos biológicos de la senescencia proporcionará valiosa información para el desarrollo de nuevas estrategias terapéuticas que detengan la progresión tumoral.

Biología del envejecimiento / Biology of aging

The study of biological aging has seen a spectacularly fast progress in the last decade. Besides a better understanding and comprehension of physiological aspects, an important advance has been the identification of at least a hundred different genes which control the process of aging. Their mechanism of action falls within the expectations from a handful of theories  which attempt to provide a global explanation of the phenomenon of aging, including free radicals, cell senescence and loss of regenerative capacity through the activation of stem cells. In this review we will concentrate in these biological aspects, with a special emphasis on animal models used to study both the genetics and physiology of aging as well as experimental approaches to test the aforementioned theories. It should be emphasized that, while the emphasis is in purely biological aspects of the process, the fast pace of aging of the world's population, including Chile, needs a rapid advance also in our understanding o fits social and economic implications.

Aspectos fisiológicos do cálcio e sua disfunção em patologias neurodegenerativas / Physiologic aspects of calcium and your dysfunction in neurodegenerative pathologies

O íon cálcio funciona como um segundo mensageiro que regula um amplo espectro de processos celulares. A diminuição ou perda do controle dos mecanismos que regulam a concentração intracelular desse íon está associada, respectivamente, ao envelhecimento dos neurônios e a doenças neurodegenerativas. A gênese dessas modificações é desconhecida. Entretanto, estudos recentes apontam para uma provável correlação entre expressão gênica alterada, estresse do retículo endoplasmático e os processos patológicos associados à disfunção na concentração intracelular do cálcio. O esclarecimento dessas questões poderá trazer novos alvos terapêuticos capazes de frear ou reverter tais alterações, combatendo, dessa forma, tanto o envelhecimento neuronal quanto as doenças neurodegenerativas.

Calcium is a second messenger that regulates a lot of cellular functions. The following mechanisms regulate the intracellular concentrations of the ion: influx, release, extrusion and storage. Decrease or loss in control of these mechanisms is related to aging of neurons and neurodegenerative diseases, respectively. The genesis of these alterations is unknown. However, recent studies point to a correlation between calcium dysfunction and altered gene expression. There is also a correlation between endoplasmic reticulum stress and pathological processes. Further investigations may reveal new therapeutical targets that can block or revert these alterations.

Envelhecer e morrer / To age and to die

Após breve consideração sobre a origem da vida, os autores questionaram o porquê de se envelhecer e evoluir para o fim. A morte celular programada (apoptose) é discutida, com seu substrato bioquímico (proteases, família, BCL-2, mediadores-chaves na ativação das caspases, inibidores da apoptose). Expõem 18 teorias que procuram explicar o envelhecimento. Relatam, de forma objetiva, as conseqüências da ação do tempo sobre os diversos órgãos e sistemas. Concluem questionando a relação de causalidade entre as teorias expostas e os achados físicos observados no processo de envelhecimento.

After some consideration on the origin of life, the authors question the reason to age and to go to an end. The programmed cellular death (apoptosis) is discussed with its biochemical substratum (proteases, BCL-2 family, key-mediators in the activation of caspases, inhibitors of apoptosis). Eighteen theories that try to explain aging are presented. The consequences of the actin of time on the variios organs and systems will be objectivelly reported. The authors conclude by questioning the relation of causality between the theories displayed and the physical findings observed in the aging process.

Regeneration of kidney tissue using in vitro cultured fetal kidney cells

Transplanting fetal kidney cells (FKCs) can regenerate kidney. This requires in vitro expansion in cell number to acquire enough cells for transplantation. However, FKCs may change their cellular characteristics during expansion and, thus, may not regenerate kidney tissue upon transplantation. We investigated how cell culture period affects cellular characteristics and in vivo regenerative potential of FKCs. As the passage number increased, cell growth rate and colony forming ability decreased while senescence and apoptosis increased. To examine in vivo regenerative potential, FKCs cultured through different numbers of passages were implanted into the parenchyma of kidneys of immunodeficient mice using fibrin gel for 4 wk. Histological analyses showed passage-dependent kidney tissue regeneration, and the regeneration was better when cells from lower number of passages were implanted. This result shows that in vitro culture of FKCs significantly affects the cell characteristics and in vivo tissue regenerative potential.

El nucléolo como un regulador del envejecimiento celular / The nucleolus as a regulator of cellular senescence

El nucléolo, considerado únicamente como el sitio de síntesis de los ribosomas, actualmente representa una estructura nuclear dinámica que participa en la regulación de importantes procesos celulares. Numerosas evidencias han demostrado que el envejecimiento celular es una de las diversas funciones que son controladas por el nucléolo. Las mutaciones en las proteínas de localización nucleolar promueven el envejecimiento prematuro en levaduras y humanos. La carencia de represión en la transcripción de genes que codifican para el ARNr que se encuentran dañados, y las mutaciones en las helicasas del ADN encargadas de minimizar la formación de círculos extra-cromosómicos del ADN que codifica para el ARNr, provocan modificaciones en la estructura del nucléolo e inducen envejecimiento prematuro en levaduras. De igual manera, en los humanos la carencia de las helicasas del ADN localizadas en el nucléolo y que participan en el mantenimiento de la integridad genómica, favorecen el desarrollo de aquellas enfermedades asociadas con el envejecimiento acelerado. Además, la presencia de algunos componentes de la telomerasa en el nucléolo, indica que parte de la biosíntesis de esta enzima se realiza en esta estructura nuclear, sugiriendo una conexión entre el nucléolo y la síntesis de los telómeros en la regulación del envejecimiento celular. Por otra parte, el nucléolo secuestra proteínas para regular su actividad biológica durante el inicio o término de la vida replicativa celular.

The nucleolus has been considered originally only as the site for the ribosome synthesis, but now it is well known that it represents a dynamic nuclear structure involved in important cellular processes. Several evidences have demonstrated that the nucleolus regulates the cellular senescence. Specific mutations on the DNAs codifying for nucleolar proteins induced premature senescence from yeast to human. The failure to repress the genes transcription codifying for damaged rRNA, and the mutations in DNA helicases, which minimizes the formation of DNA extra-chromosomal circles codifying for rRNA, modify the nucleolar structure and induce premature senescence in yeast. Similarly, in humans, the reduction of these DNA helicases levels, which are localized in the nucleoli and participate in maintenance of genomic integrity, helps to the development of those diseases associated with premature senescence. Furthermore, the presence in the nucleolus of some telomerase components, indicates that part of the biosynthesis of this enzyme occurred in this nuclear structure; suggesting a communication between the nucleolus and the synthesis of the telomeres in the regulation of cell senescence. On the other hand, the nucleolus sequesters proteins to regulate its own biological activity, from the start to the end of cellular replication. In addition this nuclear structure is involved in the biosynthesis of most cellular ribonucleoprotein particles, as well as in cell cycle regulation, making it central to gene expression. In conclusion, the nucleolus became a multifunctional subnuclear structure involved from cell proliferation to cell senescence.

Downstream molecular events in the altered profiles of lysophosphatidic acid-induced cAMP in senescent human diploid fibroblasts

Lysophosphatidic acid (LPA) is a phospholipid growth factor that acts through G-protein-coupled receptors. Previously, we demonstrated an altered profile of LPA-dependent cAMP content during the aging process of human diploid fibroblasts (HDFs). In attempts to define the molecular events associated with the age-dependent changes in cAMP profiles, we determined the protein kinase A (PKA) activity, phosphorylation of cAMP-response element binding protein (CREB), and the protein expression of CRE-regulatory genes, c-fos and COX-2 in young and senescent HDFs. We observed in senescent cells, an increase in mRNA levels of the catalytic subunit a of PKA and of the major regulatory subunit Ia. Senescence-associated increase of cAMP after LPA treatment correlated well with increased CREB phosphorylation accompanying activation of PKA in senescent cells. In senescent cells, after LPA treatment, the expression of c-fos and COX-2 decreased initially, followed by an increase. In young HDFs, CREB phosphorylation decreased following LPA treatment, and both c-fos and COX-2 protein levels increased rapidly. CRE-luciferase assay revealed higher basal CRE-dependent gene expression in young HDFs compared to senescent HDFs. However, LPA-dependent slope of luciferase increased more rapidly in senescent cells than in young cells, presumably due to an increase of LPA-induced CREB phosphorylation. CRE-dependent luciferase activation was abrogated in the presence of inhibitors of PKC, MEK1, p38MAPK, and PKA, in both young and senescent HDFs. We conclude that these kinase are coactivators of the expression of CRE-responsive genes in LPA-induced HDFs and that their changed activities during the aging process contribute to the final expression level of CRE-responsive genes.