Nutritional hormesis and aging

Oxidative stress, inflammation and hormesis: The role of dietary and lifestyle modifications on aging

Oxidative stress (OS) is primarily caused by the formation of free radicals and reactive oxygen species; it is considered as one of the prominent factors in slowing down and degrading cellular machinery of an individual, and it eventually leads to aging and age-related diseases by its continuous higher state. The relation between molecular damage and OS should be particularized to understand the beginning of destruction at the cellular levels, extending outwards to affect tissues, organs, and ultimately to the organism. Several OS biomarkers, which are established at the biomolecular level, are useful in investigating the disease susceptibility during aging. Slowing down the aging process is a matter of reducing the rate of oxidative damage to the cellular machinery over time. The breakdown of homeostasis, the mild overcompensation, the reestablishment of homeostasis, and the adaptive nature of the process are the essential features of hormesis, which incorporates several factors, including calorie restriction, nutrition and lifestyle modifications that play an important role in reducing the OS. In the current review, along with the concept and theories of aging (with emphasis on free radical theory), various manifestations of OS with special attention on mitochondrial dysfunction and age-related diseases have been discussed. To alleviate the OS, hormetic approaches including caloric restriction, exercise, and nutrition have also been discussed.

Toxicity, gut microbiota and metabolome effects after copper exposure during early life in SD rats

Copper, an essential microelement, can still be harmful to health and has a significant impact on the gut microbiota, which is closely related to health when copper is ingested excessively. However, the effects of low dose exposure to copper early in life on health and the gut microbiota are not well understood. Here, the effects of early-life exposure of copper on the toxicity, gut microbiota and the metabolome were investigated in Sprague-Dawley (SD) rats. The results showed that 0.20 and 1.00 mg/kg BW copper early-life exposure in SD rats significantly increased ALT, AST, and ALP levels in the blood and caused liver damage. Copper exposure had a dose-dependent effect on the alpha and beta diversity and reduced the abundance of probiotics, the ratio of Firmicutes to Bacteroidetes (F/B), and changed the abundance of fat metabolism and intestinal inflammation-related bacteria. The results of the fecal metabolome also demonstrated the effects of early-life copper exposure on liver damage and intestinal inflammation-related metabolic pathways. Together, our findings demonstrated that copper exposure during early life induced liver damage and gut microbiota dysbiosis and affected the relevant metabolic pathways.

Association Between Occupational Exposure to Pesticides and Cardiovascular Disease Incidence: The Kuakini Honolulu Heart Program

Background

Previously, Kuakini Honolulu Heart Program researchers reported that occupational exposure to pesticides was significantly associated with total mortality. The current study examines occupational exposure to pesticides in relation to incident cardiovascular disease, defined as coronary heart disease or cerebrovascular accident.

Methods and Results

With the Occupational Safety Health Administration exposure scale used as an estimate of exposure, statistical analyses were performed on a cohort of 7557 Japanese‐American men from the Kuakini Honolulu Heart Program. Hazard ratios for cardiovascular disease incidence were calculated for various levels of pesticide exposure using Cox proportional hazards models. In the first 10 years of follow‐up, a positive association was observed between age‐adjusted cardiovascular disease incidence and high levels of pesticide exposure (hazard ratio=1.46, 95% CI=1.10‐1.95, P=0.009). This relationship remained significant after adjustment for other cardiovascular disease risk factors (hazard ratio=1.42, 95% CI=1.05‐1.92, P=0.021). No significant association for coronary heart disease or cerebrovascular accident incidence with pesticide exposure was observed when examined separately, possibly due to a smaller number of events.

Conclusions

These findings suggest that occupational exposure to pesticides may play a role in the development of cardiovascular diseases. The results are novel, as the association between occupational exposure to pesticides and cardiovascular disease incidence has not been examined previously in this unique cohort.

The red flour beetle Tribolium castaneum allows for the convenient determination of fitness and survival as a measure of toxic effects of the food contaminant acrylamide

Acrylamide  is a toxic ingredient generated as a by-product of the Maillard reaction in starchy foods processed at temperatures above 120°C. Here we used the red flour beetle Tribolium castaneum as a model organism to test the effects of acrylamide on fitness and survival. Beetles were fed on flour spiked with acrylamide between 0.5% and 10% at 32°C over 2 weeks. Fitness of the beetles was tested by measuring the running distance and survival was recorded after 2 weeks of feeding at increased temperatures at 42°C. Both parameters were dose-dependent reduced by acrylamide. Knockdown of gene homologues of ahr, the arylhydrocarbon receptor, and of nrf-2, the nuclear factor erythroid 2-related factor 2, both reduced fitness and survival. Application of 0.5% acrylamide under knockdown of each factor further reduced fitness and survival, suggesting that ahr and nrf-2 are important for an adequate response to the toxicant. RNA-interference for ahr blocked completely the increase in nrf-2 mRNA levels, suggesting that the actions of ahr on acrylamide detoxification are mediated via Nrf-2.

Promoting longevity by maintaining metabolic and proliferative homeostasis

Aging is characterized by a widespread loss of homeostasis in biological systems. An important part of this decline is caused by age-related deregulation of regulatory processes that coordinate cellular responses to changing environmental conditions, maintaining cell and tissue function. Studies in genetically accessible model organisms have made significant progress in elucidating the function of such regulatory processes and the consequences of their deregulation for tissue function and longevity. Here, we review such studies, focusing on the characterization of processes that maintain metabolic and proliferative homeostasis in the fruitfly Drosophila melanogaster. The primary regulatory axis addressed in these studies is the interaction between signaling pathways that govern the response to oxidative stress, and signaling pathways that regulate cellular metabolism and growth. The interaction between these pathways has important consequences for animal physiology, and its deregulation in the aging organism is a major cause for increased mortality. Importantly, protocols to tune such interactions genetically to improve homeostasis and extend lifespan have been established by work in flies. This includes modulation of signaling pathway activity in specific tissues, including adipose tissue and insulin-producing tissues, as well as in specific cell types, such as stem cells of the fly intestine.

Resveratrol and vitamin D: significant potential interpretative problems arising from their mutual processes, interactions and effects

The hypothesis is formulated and presented that resveratrol and vitamin D have important mutual processes, interactions and induced effects that if not taken into account could seriously jeopardize the interpretation of their current and future preclinical, epidemiological and clinical studies. In support of this hypothesis, evidence is presented that resveratrol and vitamin D mutually share some of the same biochemical processes and mechanisms as well as the fact that they can each affect some of the same diseases and maladies.