Alzheimer's Disease and SARS-CoV-2: Pathophysiological Analysis and Social Context.

The COVID-19 pandemic has proven to be a challenge for healthcare systems, especially in terms of the care of patients with Alzheimer's disease (AD). Age is one of the major risk factors for severe forms of COVID-19, most probably due to the presence of comorbidities and inflammations. It is known that SARS-CoV-2 invades nerve endings and olfactory nerves through the binding of the spike protein to the angiotensin-converting enzyme 2 (ACE2) receptor. This interaction triggers an inflammatory cascade that results in cognitive impairment. In turn, the isoform of apolipoprotein-E4 (APOE-4ε) in AD is a risk factor for increased neuroinflammation through microglia activation, increased oxidative stress, and neurodegeneration. AD and SARS-CoV-2 are associated with increases in levels of inflammatory markers, as well as increases in levels of APOE-4ε, ACE2 and oxidative stress. Thus, there is a synergistic relationship between AD and SARS-CoV-2. In addition, the social isolation and other health measures resulting from the pandemic have led to a higher level of anxiety and depression among AD patients, a situation which may lead to a decline in cognitive function. Therefore, there is a need to develop strategies for keeping the patient calm but active.

Cognitive disorder and dementia in type 2 diabetes mellitus.

Insulin, a key pleiotropic hormone, regulates metabolism through several signaling pathways in target tissues including skeletal muscle, liver, and brain. In the brain, insulin modulates learning and memory, and impaired insulin signaling is associated with metabolic dysregulation and neurodegenerative diseases. At the receptor level, in aging and Alzheimer's disease (AD) models, the amount of insulin receptors and their functions are decreased. Clinical and animal model studies suggest that memory improvements are due to changes in insulin levels. Furthermore, diabetes mellitus (DM) and insulin resistance are associated with age-related cognitive decline, increased levels of ß-amyloid peptide, phosphorylation of tau protein; oxidative stress, pro-inflammatory cytokine production, and dyslipidemia. Recent evidence shows that deleting brain insulin receptors leads to mild obesity and insulin resistance without influencing brain size and apoptosis development. Conversely, deleting insulin-like growth factor 1 receptor (IGF-1R) affects brain size and development, and contributes to behavior changes. Insulin is synthesized locally in the brain and is released from the neurons. Here, we reviewed proposed pathophysiological hypotheses to explain increased risk of dementia in the presence of DM. Regardless of the exact sequence of events leading to neurodegeneration, there is strong evidence that mitochondrial dysfunction plays a key role in AD and DM. A triple transgenic mouse model of AD showed mitochondrial dysfunction, oxidative stress, and loss of synaptic integrity. These alterations are comparable to those induced in wild-type mice treated with sucrose, which is consistent with the proposal that mitochondrial alterations are associated with DM and contribute to AD development. Alterations in insulin/IGF-1 signaling in DM could lead to mitochondrial dysfunction and low antioxidant capacity of the cell. Thus, insulin/IGF-1 signaling is important for increased neural processing and systemic metabolism, and could be a specific target for therapeutic strategies to decrease alterations associated with age-related cognitive decline.

Effect of fish oil on oxidative stress markers in patients with probable Alzheimer´s disease

High intake of omega-3 fatty acids has been associated with synaptic plasticity, neurogenesis and memory in several experimental models. To assess the efficacy of fish oil supplementation on oxidative stress markers in patients diagnosed with probable Alzheimer´s disease (AD) we conducted a double blind, randomized, placebo controlled clinical trial. AD patients who met the inclusive criteria were given fish oil (containing 0.45 g eicosapentaenoic acid and 1 g docosahexaenoic acid) or placebo daily for 12 months. Oxidative stress markers [lipoperoxides, nitric oxide catabolites levels, oxidized/reduced glutathione ratio, and membrane fluidity] and fatty acid profile in erythrocytes were assessed at enrollment, and 6 and 12 months after the start of the testing period. At the end of the trial, in patients who received fish oil, we detected a decrease in the omega 6/omega 3 ratio in erythrocyte membrane phospholipids. This change was parallel with decreases in plasma levels of lipoperoxides and nitric oxide catabolites. Conversely, the ratio of reduced to oxidized glutathione was significantly increased. In addition, membrane fluidity was increased significantly in plasma membrane samples. In conclusion fish oil administration has a beneficial effect in decreasing the levels of oxidative stress markers and improving the membrane fluidity in plasma(AU)

El alto consumo de ácidos grasos omega-3 se asocia con la plasticidad sináptica, neurogénesis y memoria en varios modelos experimentales. Para evaluar la eficacia de la suplementación con aceite de pescado en los marcadores de estrés oxidativo en pacientes con diagnóstico de la enfermedad de Alzheimer (EA) probable realizamos un ensayo clínico doble ciego, aleatorizado, controlado con placebo. A los pacientes con la EA que cumplían los criterios de inclusión se les administró aceite de pescado (que contenía 0,45 g de ácido eicosapentaenoico y 1 g de ácido docosahexaenoico) o placebo diariamente durante 12 meses. Los marcadores de estrés oxidativo plasmático [niveles de lipoperóxidos y catabolitos del óxido nítrico, cociente de glutatión reducido a glutatiónoxidado) y fluidez de la membrana] y el perfil de ácidos grasos en los eritrocitos se evaluaron al inicio, 6 meses y alos 12 meses. Al final del ensayo, en pacientes que recibieron aceite de pescado detectamos una disminución en el cociente de ácidos grasos omega 6/omega 3 en los fosfolípidos de la membrana eritrocitaria. Este cambio ocurrió en paralelo a la disminución de los niveles plasmáticos de lipoperóxidos y catabolitos del óxido nítrico. Por el contrario, el cociente de glutatión reducido a glutatión oxidado se incrementó significativamente. Además, la fluidez de la membrana aumentó significativamente en las muestras analizadas. En conclusión, la administración de aceite de pescado tiene un efecto beneficioso al disminuir los niveles de marcadores de estrés oxidativo plasmático y mejorar la fluidez de la membrana plasmática(AU)

Effect of symbiotic supplementation on fecal calprotectin levels and lactic acid bacteria, Bifidobacteria, Escherichia coli and Salmonella DNA in patients with cervical cancer.

BACKGROUND: patients with cervical cancer (CC) receiving chemotherapy and radiotherapy have several gastrointestinal adverse effects. OBJECTIVE: to evaluate the effect of dietary symbiotic supplementation on fecal calprotectin (FCP), bacterial DNA levels, and gastrointestinal adverse effects in patients with CC. METHODS: clinical, controlled, randomized, double-blind trial. Patients consumed symbiotics or placebo three times a day for seven weeks. FCP was assessed by Elisa method. DNA from probiotic and pathogenic bacteria were determined by quantitative real-time polymerase chain reaction. Diarrheal evacuations were evaluated with the Bristol stool form scale and nausea and vomiting were measured using the scale of the National Institute of Cancerology of the United States. RESULTS: after a seven-week treatment, FCP concentration was lower in the symbiotic group compared to the control group (p < 0.001). Stool consistency in the placebo and symbiotic groups was similar at baseline. A significant improvement in stool consistency was obtained in both groups at the end of the intervention (p < 0.001). The concentrations and total proportions of the probiotic and pathogenic bacteria were similar in both groups. Nausea significantly diminished in both groups (p < 0.001) at the end of the trial. Furthermore, the symbiotic group had a statistically significant decrease in the frequency and intensity of vomiting when compared to the control group (p < 0.001). CONCLUSIONS: the symbiotic treatment decreases significantly the FCP levels and the frequency and intensity of vomiting in patients with CC.

Effect of symbiotic supplementation on fecal calprotectin levels and lactic acid bacteria, Bifidobacteria, Escherichia coli and Salmonella DNA in patients with cervical cancer / Efecto de la suplementación con simbióticos sobre los niveles de calprotectina fecal y ADN de bacterias ácido lácticas, Bifidobacteria, Escherichia coli y Salmonella en pacientes con cáncer cervical

Background: patients with cervical cancer (CC) receiving chemotherapy and radiotherapy have several gastrointestinal adverse effects. Objective: to evaluate the effect of dietary symbiotic supplementation on fecal calprotectin (FCP), bacterial DNA levels, and gastrointestinal adverse effects in patients with CC. Methods: clinical, controlled, randomized, double-blind trial. Patients consumed symbiotics or placebo three times a day for seven weeks. FCP was assessed by Elisa method. DNA from probiotic and pathogenic bacteria were determined by quantitative real-time polymerase chain reaction. Diarrheal evacuations were evaluated with the Bristol stool form scale and nausea and vomiting were measured using the scale of the National Institute of Cancerology of the United States. Results: after a seven-week treatment, FCP concentration was lower in the symbiotic group compared to the control group (p < 0.001). Stool consistency in the placebo and symbiotic groups was similar at baseline. A significant improvement in stool consistency was obtained in both groups at the end of the intervention (p < 0.001). The concentrations and total proportions of the probiotic and pathogenic bacteria were similar in both groups. Nausea significantly diminished in both groups (p < 0.001) at the end of the trial. Furthermore, the symbiotic group had a statistically significant decrease in the frequency and intensity of vomiting when compared to the control group (p < 0.001). Conclusions: the symbiotic treatment decreases significantly the FCP levels and the frequency and intensity of vomiting in patients with CC

Introducción: los pacientes con cáncer cervical (CC) tratados con quimioterapia y radioterapia tienen frecuentemente efectos gastrointestinales adversos (EGA). Objetivo: evaluar el efecto de la suplementación dietética con simbióticos en la calprotectina fecal (FCP), el DNA bacteriano y sobre los EGA en pacientes con CC. Métodos: se realizó un ensayo clínico, aleatorizado y doble ciego. Los pacientes ingirieron simbióticos o placebo tres veces al día durante siete semanas. La FCP se evaluó mediante el método de ELISA. El ADN bacteriano se cuantificó mediante PCR en tiempo real. Las evacuaciones se evaluaron con la escala de Bristol y las náuseas y los vómitos se cuantificaron utilizando la escala del Instituto Nacional de Cancerología (USA). Resultados: después de siete semanas de tratamiento, la concentración de FCP fue menor en el grupo tratado con simbióticos en comparación al grupo control (p < 0,001). La consistencia de las heces en los grupos tratados con placebo y simbióticos fue similar al inicio del estudio. Se obtuvo una mejora significativa en la consistencia de las heces en ambos grupos al final de la intervención (p < 0,001). Los niveles de las bacterias probióticas y patogénicas fueron similares en ambos grupos. Los casos de náuseas disminuyeron en ambos grupos (p < 0,001) y el grupo tratado con simbióticos tuvo una disminución significativa en la frecuencia e intensidad de los vómitos en comparación al grupo control (p < 0,001). Conclusiones: el tratamiento simbiótico disminuye significativamente los niveles de FCP y la frecuencia e intensidad del vómito en pacientes con CC

Efficacy of Melatonin on Serum Pro-inflammatory Cytokines and Oxidative Stress Markers in Relapsing Remitting Multiple Sclerosis.

Multiple sclerosis (MS) is a chronic inflammatory disease, which leads to focal plaques of demyelination and tissue injury in the central nervous system (CNS). Neuroinflammation and oxidative stress are involved in the pathogenesis of MS, promoting tissue damage and demielinization. Current research findings suggest that melatonin has antioxidant and neuroprotective effects. The aim of this study was to evaluate the efficacy of melatonin on serum pro-inflammatory cytokines and oxidative stress markers in relapsing-remitting multiple sclerosis (RRMS). 36 patients diagnose with RRMS treated with Interferon ß-1b (IFNß-1b) were enrolled in a double bind, randomized, placebo controlled trial. The experimental group received orally 25 mg/d of melatonin for 6 months. After melatonin administration, we observed a significant decrease in serum concentration of pro-inflammatory cytokines and oxidative stress markers; 18% for TNF-α (p <0.05), 34.8% for IL-1ß (p <0.05), 34.7% for IL-6 (p <0.05), 39.9% for lipoperoxides (LPO) (p <0.05) and 24% for nitric oxide catabolites (NOC) levels (p <0.05), compared with placebo group. No significant difference in clinical efficacy outcomes were found between groups. Melatonin treatment was well tolerated and we did not observe significant differences in rates of side effects between the two groups. We concluded that melatonin administration during 6 months period is effective in reducing levels of serum pro-inflammatory cytokines and oxidative stress markers in patients with RRMS. These data support future studies evaluating the safety and effectiveness of melatonin supplementation in RRMS patients.

Effect of fish oil on glutathione redox system in multiple sclerosis.

UNLABELLED: Multiple sclerosis (MS) is a chronic, inflammatory and autoimmune disease of the central nervous system. Dysregulation of glutathione homeostasis and alterations in glutathione-dependent enzyme activities are implicated in the induction and progression of MS. Evidence suggests that Omega-3 polyunsaturated fatty acids (PUFAs) have anti-inflammatory, antioxidant and neuroprotective effects. The aim of the present work was to evaluate the effect of fish oil on the activity of glutathione reductase (GR), content of reduced and oxidized glutathione, and GSH/GSSG ratio in MS. 50 patients with relapsing-remitting MS were enrolled. The experimental group received orally 4 g/day of fish oil for 12 months. Fish oil supplementation resulted in a significant increase in n-3 fatty acids and a decrease n-6 fatty acids. No differences in glutathione reductase activity, content of reduced and oxidized glutathione, and GSH/GSSG ratio were found. CONCLUSION: Glutathione reductase activity was not significantly different between the groups; however, fish oil supplementation resulted in smaller increase in GR compared with control group, suggesting a possible effect on antioxidant defence mechanisms.

Prevalence of Dementia, Emotional State and Physical Performance among Older Adults in the Metropolitan Area of Guadalajara, Jalisco, Mexico.

Background. Dementia affects memory, thinking, language, judgment, and behavior. Depression, is common in older adults with dementia. The concomitance of dementia and depression increases disability with impaired activities of daily living (ADL), increasing the chances of institutionalization and mortality. Methods. Cross-sectional study of a population 60 years and older who live in the State of Jalisco, Mexico. A total of 1142 persons were assessed regarding their cognitive function, emotional state, and physical performance. Door-to-door interview technique was assigned in condition with multistage probability random sampling. Cognitive function, depression and functional disability were assessed by applying standardized Minimental State Examination (Folstein), Geriatric Depression Scale, and the Katz index, respectively. Diagnosis of dementia was performed according to the criteria of the Diagnostic and Statistical Manual of Mental Disorders, the Fourth Edition. Data were analyzed using SPSS software. Results. Prevalence of demency was 9.5% (63.35% women, and 36.7% men). Demency was associated with being woman, being older than 70 years, low level of education, not having the economic benefit of retirement, being single or living without a partner, low level of education, suffering from depression and have functional disability in ADL. Conclusion. Dementia is more common in women and is related to depression and disability.

Novel Point Mutations and A8027G Polymorphism in Mitochondrial-DNA-Encoded Cytochrome c Oxidase II Gene in Mexican Patients with Probable Alzheimer Disease.

Mitochondrial dysfunction has been thought to contribute to Alzheimer disease (AD) pathogenesis through the accumulation of mitochondrial DNA mutations and net production of reactive oxygen species (ROS). Mitochondrial cytochrome c-oxidase plays a key role in the regulation of aerobic production of energy and is composed of 13 subunits. The 3 largest subunits (I, II, and III) forming the catalytic core are encoded by mitochondrial DNA. The aim of this work was to look for mutations in mitochondrial cytochrome c-oxidase gene II (MTCO II) in blood samples from probable AD Mexican patients. MTCO II gene was sequenced in 33 patients with diagnosis of probable AD. Four patients (12%) harbored the A8027G polymorphism and three of them were early onset (EO) AD cases with familial history of the disease. In addition, other four patients with EOAD had only one of the following point mutations: A8003C, T8082C, C8201T, or G7603A. Neither of the point mutations found in this work has been described previously for AD patients, and the A8027G polymorphism has been described previously; however, it hasn't been related to AD. We will need further investigation to demonstrate the role of the point mutations of mitochondrial DNA in the pathogenesis of AD.

Epidemiología de infecciones nosocomiales en el Instituto Jalisciense de Cancerología / Epidemiology of nosocomial infections in Instituto Jalisciense de Cancerología

Introducción: las intervenciones durante el tratamiento en el paciente oncológico, aumentan los riesgos para sufrir una infección nosocomial. En el Instituto Jalisciense de Cancerología, la prevención, identificación y seguimiento de las infecciones nosocomiales se realiza a través del programa de epidemiologia y por el Comité de Vigilancia Epidemiológica. Objetivos: determinar la incidencia de infecciones nosocomiales en pacientes oncológicos atendidos en el citado instituto. Métodos: se trata de un estudio descriptivo retrospectivo. Se tomaron en cuenta 5 056 egresos de abril de 2008 a diciembre de 2010, de los cuales 140 pacientes presentaron 178 infecciones nosocomiales. Resultados: la tasa global de infecciones por 100 egresos, fue variable (2008: 5,8; en 2009: 3,5 y en 2010: 2,2). La infección de herida quirúrgica se mantuvo con las tasas más altas (2,9; 1,5; 1,1). El germen más frecuentemente aislado fue Escherichia coli (55 %, 34 %, 20 %), el hongo más frecuente fue la Candida albicans (6 %, 7 %, 6 %). El promedio días estancia en el momento de la captación de la infección, fue de 3,3 días y en el momento del egreso fue de 17 días. La tasa de letalidad, fue de 19 por cada 100 casos, y la tasa de mortalidad 27 por cada 100 casos. Conclusiones: se observa una disminución en la tasa de infección nosocomial en los últimos años. La intervención del Servicio de Epidemiología con sus acciones dirigidas de manera específica, al manejo de las heridas quirúrgicas, es fundamental.

Background: the treatments in cancer patients increase the risk of catching nosocomial infection. In the Instituto Jalisciense de Cancerología, the prevention, identification and monitoring of nosocomial infections is carried out by the Epidemiological Surveillance Committee through an epidemiological program. Objectives: To determine the incidence of nosocomial infections in cancer patients seen at the Instituto Jalisciense de Cancerología Methods: A retrospective and descriptive study, which included 5056 patients discharged from April 2008 to December 2010, of whom 140 had nosocomial infections. Results: The overall rate of infections per 100 discharges was variable (5.8 in 2008; 3.5 in 2009 and 2.2 in 2010). The surgical wound infection kept the highest rates (2.9, 1.5, 1.1 respectively). The most common isolated bacteria was Escherichia coli (55 %, 34 %, 20 %); the most frequent fungus was Candida albicans (6 %, 7 %, 6 %). The average length of stay at the time of catching the infection was 3.3 days, and at the time of hospital discharge was 17 days. The fatality rate was 19 per 100 cases whereas the mortality rate was 27 per 100 cases. Conclusions: a decrease in the rate of nosocomial infection was observed in recent years; where the epidemiology service was the key to implementing epidemiological actions, in particular the management of surgical wounds.

Prevalence of Cognitive Impairment and Depression among a Population Aged over 60 Years in the Metropolitan Area of Guadalajara, Mexico.

Background. Cognitive impairment is an important clinical issue among elderly patients with depression and has a more complex etiology because of the variable rate of neurodegenerative changes associated with depression. The aim of the present work was to examine the prevalence of cognitive impairment and depression in a representative sample of adults aged ≥60 years. Methods. The presented work was a cross-sectional study on the prevalence of cognitive impairment and depression. Door-to-door interview technique was assigned in condition with multistage probability random sampling to obtain subjects that represent a population of the Guadalajara metropolitan area (GMA), Mexico. Cognitive function and depression were assessed by applying standardized Mini-Mental State Examination of Folstein (MMSE) and the Geriatric Depression Scale (GDS), respectively. Results. Prevalence of cognitive impairment was 13.8% (14.5% women, 12.6% men); no significant differences by gender and retired or pensioner were found. Prevalence of depression was 29.1% (33.6% women, 21.1% men); no significant differences by retired or pensioner were found. Cognitive impairment was associated with depression (OR = 3.26, CI 95%, 2.31-4.60). Prevalence of cognitive impairment and depression is associated with: being woman, only in depression being older than 75 years being married, and a low level of education. Conclusion. Cognitive impairment and depression are highly correlated in adults aged ≥60.

Envejecimiento y metabolismo: cambios y regulación

Los estudios sobre los efectos del envejecimiento en la fisiología y el metabolismo cada vez son más, uno de sus objetivos es contribuir a instrumentar programas para mejorar la calidad de vida y prevenir discapacidades en la vejez. Es de gran importancia mencionar que durante el envejecimiento se presenta una desaceleración natural del metabolismo, se produce una serie de cambios en la regulación de la energía, lo que contribuye a la pérdida de peso y grasa; estos cambios en la regulación de la ingesta calórica contribuyen en un aumento de la susceptibilidad al desequilibrio energético tanto positivo como negativo, lo cual va asociado a un deterioro en la salud. Sin embargo, el llegar a la vejez, no es una sentencia de muerte para el metabolismo, por el contrario, éste puede ser controlado mediante el mantenimiento de un estilo de vida activo, aunado a esto investigaciones han demostrado que el metabolismo puede ser regulado mediante el papel que desempeña un sistema de reloj sincronizado (ritmos biológicos), el cual a su vez es modulado por varias proteínas reguladoras; esta relación garantiza que las células funcionen correctamente y por tanto el mantenerse saludables. El objetivo de esta revisión es aportar información actualizada sobre la regulación metabolismo-energía y su relación con la gran variedad de componentes involucrados en el gasto energético que acompañan al envejecimiento; analizar la regulación de este sistema para mejorar la calidad de vida y mantener la salud en la vejez.

Aging and metabolism: changes and regulation. Studies about the effects of aging in the physiology and metabolism are increasingly, one of its objectives is to help implement programs to improve the quality of life and prevent disability in elderly. It is relevant to mention that, during aging, there is a natural metabolic deceleration, a series of changes in the regulation of energy are produced, which contributes to loss of weight and fat; the changes in the regulation of caloric intake contribute to increase the susceptibility to energy imbalance both positive and negative, which is associated with a deterioration in health. However, to grow old, is not a death sentence for metabolism, on the other hand, it can be controlled by maintaining an active lifestyle, coupled with this, research has shown that the metabolism can be regulated by a synchronized clock (circadian rhythms), which is mediated by regulatory proteins, this relationship ensures the proper functioning of the cells and therefore good health. The aim of this review is to provide updated information on the energy- metabolism-regulation and its relationship with the great variety of components involved in energy expenditure that accompany aging, to analyze the regulation of this system to improve the quality of life and maintenance of health in old age.

Physical function and associated factors in community-dwelling elderly people in Jalisco, Mexico.

PURPOSE: To determine the prevalence of disability in Basic Activities of Daily Living and Instrumental Activities of Daily Living (ADL and IADL, respectively), as well as associated factors in the Mexican community-dwelling elderly population. MATERIALS AND METHODS: This is a cross-sectional study of a population 60 years and older who live in the State of Jalisco (Mexico). A total of 2553 persons were assessed regarding their functional and health conditions. The ADL and IADL were classified as dependent and non-dependent, and crude and adjusted Odds Ratio (OR) were calculated. RESULTS: Mean age of participants was 71.6±8.7, 61.2% were women. A disability prevalence of 9.6% was found to perform ADL and of 31.5% for the IADL, 14.3% had cognitive impairment and 30.9% depression. Risk factors were found for dependence: being a woman, being ≥75 years old, low education level, having at least one chronic disease, cognitive impairment, depression, previous history of disability, and having been a lifelong housewife. CONCLUSIONS: Functional difficulties are common in Mexican elderly population. These data show key variables for functional disability risk. A better understanding of functional capabilities, as well as of risk factors older adults face every day provide us with a guide to devise a prevention plan, to implement adequate interventions, or to provide appropriate care.

[Aging and metabolism: changes and regulation]. / Envejecimiento y metabolismo: cambios y regulación.

Studies about the effects of aging in the physiology and metabolism are increasingly, one of its objectives is to help implement programs to improve the quality of life and prevent disability in elderly. It is relevant to mention that, during aging, there is a natural metabolic deceleration, a series of changes in the regulation of energy are produced, which contributes to loss of weight and fat; the changes in the regulation of caloric intake contribute to increase the susceptibility to energy imbalance both positive and negative, which is associated with a deterioration in health. However, to grow old, is not a death sentence for metabolism, on the other hand, it can be controlled by maintaining an active lifestyle, coupled with this, research has shown that the metabolism'can be regulated by a synchronized clock (circadian rhythms), which is mediated by regulatory proteins, this relationship ensures the proper functioning of the cells and therefore good health. The aim of this review is to provide updated information on the energy- metabolism-regulation and its relationship with the great variety of components involved in energy expenditure that accompany aging, to analyze the regulation of this system to improve the quality of life and maintenance of health in old age.

Cellular and biochemical actions of melatonin which protect against free radicals: role in neurodegenerative disorders.

Molecular oxygen is toxic for anaerobic organisms but it is also obvious that oxygen is poisonous to aerobic organisms as well, since oxygen plays an essential role for inducing molecular damage. Molecular oxygen is a triplet radical in its ground-stage (.O-O.) and has two unpaired electrons that can undergoes consecutive reductions of one electron and generates other more reactive forms of oxygen known as free radicals and reactive oxygen species. These reactants (including superoxide radicals, hydroxyl radicals) possess variable degrees of toxicity. Nitric oxide (NO*) contains one unpaired electron and is, therefore, a radical. NO* is generated in biological tissues by specific nitric oxide synthases and acts as an important biological signal. Excessive nitric oxide production, under pathological conditions, leads to detrimental effects of this molecule on tissues, which can be attributed to its diffusion-limited reaction with superoxide to form the powerful and toxic oxidant, peroxynitrite.Reactive oxygen and nitrogen species are molecular "renegades"; these highly unstable products tend to react rapidly with adjacent molecules, donating, abstracting, or even sharing their outer orbital electron(s). This reaction not only changes the target molecule, but often passes the unpaired electron along to the target, generating a second free radical, which can then go on to react with a new target amplifying their effects.This review describes the mechanisms of oxidative damage and its relationship with the most highly studied neurodegenerative diseases and the roles of melatonin as free radical scavenger and neurocytoskeletal protector.

Síndrome de burnout y factores psicosociales en el trabajo, en estudiantes de postgrado del Departamento de Salud Pública de la Universidad de Guadalajara, México / Burnout syndrome and job-related psychosocial factors in graduate students of the department of Public Health of University of Guadalajara, Mexico

Es conocido que el síndrome de burnout se da sobre todo en personas que trabajan con personas y que los profesionales de la salud son los más propensos a desarrollarlo. El objetivo del estudio fue el de determinar la prevalencia del síndrome de burnout, así como analizar su posible relación con la presencia de factores psicosociales negativos en el trabajo, en los estudiantes de postgrado del Departamento de Salud Pública de la Universidad de Guadalajara, México. Los instrumentos de evaluación utilizados fueron: el cuestionario de datos sociodemográficos, la Escala de Valoración de Maslach burnout Inventory (MBI) para evaluar el síndrome y la Guía de Identificación de Factores Psicosociales para identificar la presencia de factores psicosociales negativos en el área de trabajo. El total de alumnos inscritos en los diferentes postgrados fue de 54 alumnos, 46,3 por ciento son mujeres y 53,7 por ciento son hombres, con un promedio dé edad de 35,9 años. El 94,4 por ciento de ellos trabajan en algún puesto directivo, principalmente en Instituciones de Servicios de Salud. La prevalencia encontrada para el síndrome de burnout fue del 56,9 por ciento. Las diferencias estadísticas significativas se obtuvieron sobre todo entre los datos sociodemográficos con la presencia de factores psicosociales negativos en el trabajo, así como con el área que evalúa la presencia de factores psicosociales "dependientes del sistema de trabajo" con la dimensión "agotamiento emocional" de la Escala de Maslach (p= 0,0366).Debe ser suma preocupación por parte de las organizaciones el mejorar el estado de salud físico y mental de sus trabajadores con miras hacia una mejor calidad de vida del trabajador. (AU)