Visual comet scoring revisited: a guide to scoring comet assay slides and obtaining reliable results.

Measurement of DNA migration in the comet assay can be done by image analysis or visual scoring. The latter accounts for 20%-25% of the published comet assay results. Here we assess the intra- and inter-investigator variability in visual scoring of comets. We include three training sets of comet images, which can be used as reference for researchers who wish to use visual scoring of comets. Investigators in 11 different laboratories scored the comet images using a five-class scoring system. There is inter-investigator variation in the three training sets of comets (i.e. coefficient of variation (CV) = 9.7%, 19.8%, and 15.2% in training sets I-III, respectively). However, there is also a positive correlation of inter-investigator scoring in the three training sets (r = 0.60). Overall, 36% of the variation is attributed to inter-investigator variation and 64% stems from intra-investigator variation in scoring between comets (i.e. the comets in training sets I-III look slightly different and this gives rise to heterogeneity in scoring). Intra-investigator variation in scoring was also assessed by repeated analysis of the training sets by the same investigator. There was larger variation when the training sets were scored over a period of six months (CV = 5.9%-9.6%) as compared to 1 week (CV = 1.3%-6.1%). A subsequent study revealed a high inter-investigator variation when premade slides, prepared in a central laboratory, were stained and scored by investigators in different laboratories (CV = 105% and 18%-20% in premade slides with comets from unexposed and hydrogen peroxide-exposed cells, respectively). The results indicate that further standardization of visual scoring is desirable. Nevertheless, the analysis demonstrates that visual scoring is a reliable way of analysing DNA migration in comets.

Inter-laboratory variation in measurement of DNA damage by the alkaline comet assay in the hCOMET ring trial.

The comet assay is a simple and versatile method for measurement of DNA damage in eukaryotic cells. More specifically, the assay detects DNA migration from agarose gel-embedded nucleoids, which depends on assay conditions and the level of DNA damage. Certain steps in the comet assay procedure have substantial impact on the magnitude of DNA migration (e.g. electric potential and time of electrophoresis). Inter-laboratory variation in DNA migration levels occurs because there is no agreement on optimal assay conditions or suitable assay controls. The purpose of the hCOMET ring trial was to test potassium bromate (KBrO3) as a positive control for the formamidopyrimidine DNA glycosylase (Fpg)-modified comet assay. To this end, participating laboratories used semi-standardized protocols for cell culture (i.e. cell culture, KBrO3 exposure, and cryopreservation of cells) and comet assay procedures, whereas the data acquisition was not standardized (i.e. staining of comets and image analysis). Segregation of the total variation into partial standard deviation (SD) in % Tail DNA units indicates the importance of cell culture procedures (SD = 10.9), comet assay procedures (SD = 12.3), staining (SD = 7.9) and image analysis (SD = 0.5) on the overall inter-laboratory variation of DNA migration (SD = 18.2). Future studies should assess sources of variation in each of these steps. On the positive side, the hCOMET ring trial demonstrates that KBrO3 is a robust positive control for the Fpg-modified comet assay. In conclusion, the hCOMET ring trial has demonstrated a high reproducibility of detecting genotoxic effects by the comet assay, but inter-laboratory variation of DNA migration levels is a concern.

DNA strand break levels in cryopreserved mononuclear blood cell lines measured by the alkaline comet assay: results from the hCOMET ring trial.

The comet assay is widely used in biomonitoring studies for the analysis of DNA damage in leukocytes and peripheral blood mononuclear cells. Rather than processing blood samples directly, it can be desirable to cryopreserve whole blood or isolated cells for later analysis by the comet assay. However, this creates concern about artificial accumulation of DNA damage during cryopreservation. In this study, 10 laboratories used standardized cryopreservation and thawing procedures of monocytic (THP-1) or lymphocytic (TK6) cells. Samples were cryopreserved in small aliquots in 50% foetal bovine serum, 40% cell culture medium, and 10% dimethyl sulphoxide. Subsequently, cryopreserved samples were analysed by the standard comet assay on three occasions over a 3-year period. Levels of DNA strand breaks in THP-1 cells were increased (four laboratories), unaltered (four laboratories), or decreased (two laboratories) by long-term storage. Pooled analysis indicates only a modest positive association between storage time and levels of DNA strand breaks in THP-1 cells (0.37% Tail DNA per year, 95% confidence interval: -0.05, 0.78). In contrast, DNA strand break levels were not increased by cryopreservation in TK6 cells. There was inter-laboratory variation in levels of DNA strand breaks in THP-1 cells (SD = 3.7% Tail DNA) and TK6 reference sample cells (SD = 9.4% Tail DNA), whereas the intra-laboratory residual variation was substantially smaller (i.e. SD = 0.4%-2.2% Tail DNA in laboratories with the smallest and largest variation). In conclusion, the study shows that accumulation of DNA strand breaks in cryopreserved mononuclear blood cell lines is not a matter of concern.

Long-term cryopreservation of potassium bromate positive assay controls for measurement of oxidatively damaged DNA by the Fpg-modified comet assay: results from the hCOMET ring trial.

The formamidopyrimidine DNA glycosylase (Fpg)-modified comet assay is widely used for the measurement of oxidatively generated damage to DNA. However, there has not been a recommended long-term positive control for this version of the comet assay. We have investigated potassium bromate as a positive control for the Fpg-modified comet assay because it generates many Fpg-sensitive sites with a little concurrent generation of DNA strand breaks. Eight laboratories used the same procedure for the treatment of monocytic THP-1 cells with potassium bromate (0, 0.5, 1.5, and 4.5 mM) and subsequent cryopreservation in a freezing medium consisting of 50% foetal bovine serum, 40% RPMI-1640 medium, and 10% dimethyl sulphoxide. The samples were analysed by the Fpg-modified comet assay three times over a 3-year period. All laboratories obtained a positive concentration-response relationship in cryopreserved samples (linear regression coefficients ranging from 0.79 to 0.99). However, there was a wide difference in the levels of Fpg-sensitive sites between the laboratory with the lowest (4.2% Tail DNA) and highest (74% Tail DNA) values in THP-1 cells after exposure to 4.5 mM KBrO3. In an attempt to assess sources of inter-laboratory variation in Fpg-sensitive sites, comet images from one experiment in each laboratory were forwarded to a central laboratory for visual scoring. There was high consistency between measurements of %Tail DNA values in each laboratory and the visual score of the same comets done in the central laboratory (r = 0.98, P < 0.001, linear regression). In conclusion, the results show that potassium bromate is a suitable positive comet assay control.

Assessing the in vitro toxicity of airborne (nano)particles to the human respiratory system: from basic to advanced models.

Several studies have been conducted to address the potential adverse health risks attributed to exposure to nanoscale materials. While in vivo studies are fundamental for identifying the relationship between dose and occurrence of adverse effects, in vitro model systems provide important information regarding the mechanism(s) of action at the molecular level. With a special focus on exposure to inhaled (nano)particulate material toxicity assessment, this review provides an overview of the available human respiratory models and exposure systems for in vitro testing, advantages, limitations, and existing investigations using models of different complexity. A brief overview of the human respiratory system, pathway and fate of inhaled (nano)particles is also presented.

Association of Torquetenovirus Viremia with Physical Frailty and Cognitive Impairment in Three Independent European Cohorts.

INTRODUCTION: Immunosenescence and inflammaging have been implicated in the pathophysiology of frailty. Torquetenovirus (TTV), a single-stranded DNA anellovirus, the major component of the human blood virome, shows an increased replication rate with advancing age. An elevated TTV viremia has been associated with an impaired immune function and an increased risk of mortality in the older population. The objective of this study was to analyze the relation between TTV viremia, physical frailty, and cognitive impairment. METHODS: TTV viremia was measured in 1,131 nonfrail, 45 physically frail, and 113 cognitively impaired older adults recruited in the MARK-AGE study (overall mean age 64.7 ± 5.9 years), and then the results were checked in two other independent cohorts from Spain and Portugal, including 126 frail, 252 prefrail, and 141 nonfrail individuals (overall mean age: 77.5 ± 8.3 years). RESULTS: TTV viremia ≥4log was associated with physical frailty (OR: 4.69; 95% CI: 2.06-10.67, p < 0.0001) and cognitive impairment (OR: 3.49, 95% CI: 2.14-5.69, p < 0.0001) in the MARK-AGE population. The association between TTV DNA load and frailty status was confirmed in the Spanish cohort, while a slight association with cognitive impairment was observed (OR: 1.33; 95% CI: 1.000-1.773), only in the unadjusted model. No association between TTV load and frailty or cognitive impairment was found in the Portuguese sample, although a negative association between TTV viremia and MMSE score was observed in Spanish and Portuguese females. CONCLUSIONS: These findings demonstrate an association between TTV viremia and physical frailty, while the association with cognitive impairment was observed only in the younger population from the MARK-AGE study. Further research is necessary to clarify TTV's clinical relevance in the onset and progression of frailty and cognitive decline in older individuals.

Effects of Zinc Oxide Nanoparticle Exposure on Human Glial Cells and Zebrafish Embryos.

Zinc oxide nanoparticles (ZnO NPs) are among the most widely used nanomaterials. They have multiple applications in cosmetics, textiles, paints, electronics and, recently, also in biomedicine. This extensive use of ZnO NPs notably increases the probability that both humans and wildlife are subjected to undesirable effects. Despite being among the most studied NPs from a toxicological point of view, much remains unknown about their ecotoxicological effects or how they may affect specific cell types, such as cells of the central nervous system. The main objective of this work was to investigate the effects of ZnO NPs on human glial cells and zebrafish embryo development and to explore the role of the released Zn2+ ions in these effects. The effects on cell viability on human A172 glial cells were assessed with an MTT assay and morphological analysis. The potential acute and developmental toxicity was assessed employing zebrafish (Danio rerio) embryos. To determine the role of Zn2+ ions in the in vitro and in vivo observed effects, we measured their release from ZnO NPs with flame atomic absorption spectrometry. Then, cells and zebrafish embryos were treated with a water-soluble salt (zinc sulfate) at concentrations that equal the number of Zn2+ ions released by the tested concentrations of ZnO NPs. Exposure to ZnO NPs induced morphological alterations and a significant decrease in cell viability depending on the concentration and duration of treatment, even after removing the overestimation due to NP interference. Although there were no signs of acute toxicity in zebrafish embryos, a decrease in hatching was detected after exposure to the highest ZnO NP concentrations tested. The ability of ZnO NPs to release Zn2+ ions into the medium in a concentration-dependent manner was confirmed. Zn2+ ions did not seem entirely responsible for the effects observed in the glial cells, but they were likely responsible for the decrease in zebrafish hatching rate. The results obtained in this work contribute to the knowledge of the toxicological potential of ZnO NPs.

Toxicological Aspects of Iron Oxide Nanoparticles.

Iron oxide nanoparticles (ION), with unique magnetic properties, have attracted huge scientific attention for a wide variety of uses, mostly in the biomedical field, due to their high biocompatibility, ability to cross biological membranes, appropriate surface architecture and easy conjugation with targeting ligands. Their current applications include diagnostic imaging, cell labelling, site-directed drug delivery and anticancer hyperthermia therapy. The ION surface may be modified by coating with different materials, aiming to stabilize the nanoparticles in different environments, to allow biomolecule binding favouring surface attachments with several molecules, and to prolong the recognition time by the immune system. Although the potential benefits of ION are considerable, and more and more ION are being manufactured to meet the demands of the rapidly proliferating field of nanomedicine, there is an urgent need to define their toxicological profile in order to avoid any potential health risks associated with their exposure and to reach optimal benefits of their use. The purpose of this chapter is to de-scribe the current knowledge on the ION toxicological features, addressing their structure and physicochemical characteristics, main exposure pathways and toxicokinetic aspects, interaction with cells, and their toxic effects, with special attention to those at the cellular and molecular level.

Collection and storage of human white blood cells for analysis of DNA damage and repair activity using the comet assay in molecular epidemiology studies.

DNA damage and repair activity are often assessed in blood samples from humans in different types of molecular epidemiology studies. However, it is not always feasible to analyse the samples on the day of collection without any type of storage. For instance, certain studies use repeated sampling of cells from the same subject or samples from different subjects collected at different time-points, and it is desirable to analyse all these samples in the same comet assay experiment. In addition, flawless comet assay analyses on frozen samples open up the possibility of using this technique on biobank material. In this article we discuss the use of cryopreserved peripheral blood mononuclear cells (PBMCs), buffy coat (BC) and whole blood (WB) for analysis of DNA damage and repair using the comet assay. The published literature and the authors' experiences indicate that various types of blood samples can be cryopreserved with only a minor effect on the basal level of DNA damage. There is evidence to suggest that WB and PBMCs can be cryopreserved for several years without much effect on the level of DNA damage. However, care should be taken when cryopreserving WB and BCs. It is possible to use either fresh or frozen samples of blood cells, but results from fresh and frozen cells should not be used in the same dataset. The article outlines detailed protocols for the cryopreservation of PBMCs, BCs and WB samples.

Salivary leucocytes as suitable biomatrix for the comet assay in human biomonitoring studies.

Peripheral blood leucocytes (PBL) have been traditionally used to investigate DNA damage by the comet assay in population studies, but validating alternative non-invasive samples would expand the application of this assay in human biomonitoring. The objectives of this study were (i) to test the validity of salivary leucocytes as a proper biomatrix for the comet assay, (ii) to evaluate the ability of this approach to detect different types of primary and oxidative DNA damage, and (iii) to determine whether frozen salivary leucocytes are still suitable for displaying those types of DNA damage. Fresh and frozen leucocytes isolated from saliva samples (six healthy non-smoking volunteers), were exposed to four genotoxic agents inducing different types of DNA damage, both primary (methyl methanesulfonate, actinomycin-D, ultraviolet radiation) and oxidative (potassium bromate), and standard or enzyme-modified comet assay was conducted. Results were compared with those obtained from PBL. Cells exposed to the four genotoxic agents showed dose-dependent increases of primary and oxidative DNA damage, demonstrating the suitability of all these samples to detect genetic damage from different origin. When comparing baseline levels of DNA damage, just a slight significant increase in primary DNA damage was observed in frozen salivary leucocytes regarding the other biomatrices, but similar results were obtained regarding sensitivity to DNA damage induction by all agents tested. This study demonstrates that salivary leucocytes can be employed in comet assay as an alternative or complement to blood samples. Frozen salivary leucocytes were proved to be a very convenient sample in large biomonitoring studies.

Applicability of flow cytometry γH2AX assay in population studies: suitability of fresh and frozen whole blood samples.

Phosphorylation of H2AX histone (γH2AX) represents an early event in the DNA damage response against double-strand breaks (DSB); hence, its measurement provides a surrogate biomarker of DSB. Recently, we reported initial steps in the standardization of γH2AX assay in peripheral blood leukocytes (PBL), addressing the possibility of using cryopreserved samples, and the need of phytohaemagglutinin (PHA) stimulation prior analysis (Toxicol Sci 2015, 144:406-13). Validating the use of whole blood samples as cell specimen for this assay would be particularly useful for human population studies. Hence, in the current study we determined for the first time the feasibility of whole blood samples, both fresh and frozen, to be used in the γH2AX assay, evaluated by flow cytometry, and the convenience of PHA stimulation. Freshly collected and cryopreserved whole blood samples were treated with bleomycin (BLM), actinomycin-D (Act-D) and mitomycin C (MMC); half of the samples were previously incubated with PHA. Results were compared with those from PBL. Negative responses in MMC treatments were probably due to the quiescence of unstimulated cells, or to the short treatment time in PHA stimulated cells. Fresh whole blood samples exhibited a more intense response to BLM and Act-D treatments in stimulated cells, probably due to DSB indirectly produced from other less relevant types of DNA damage. Results obtained in frozen whole blood samples indicate that PHA stimulation is not advisable. In conclusion, this study demonstrates that whole blood samples can be used to assess DSB-related genotoxicity by the flow cytometry γH2AX assay.

Suitability of the In Vitro Cytokinesis-Block Micronucleus Test for Genotoxicity Assessment of TiO2 Nanoparticles on SH-SY5Y Cells.

Standard toxicity tests might not be fully adequate for evaluating nanomaterials since their unique features are also responsible for unexpected interactions. The in vitro cytokinesis-block micronucleus (CBMN) test is recommended for genotoxicity testing, but cytochalasin-B (Cyt-B) may interfere with nanoparticles (NP), leading to inaccurate results. Our objective was to determine whether Cyt-B could interfere with MN induction by TiO2 NP in human SH-SY5Y cells, as assessed by CBMN test. Cells were treated for 6 or 24 h, according to three treatment options: co-treatment with Cyt-B, post-treatment, and delayed co-treatment. Influence of Cyt-B on TiO2 NP cellular uptake and MN induction as evaluated by flow cytometry (FCMN) were also assessed. TiO2 NP were significantly internalized by cells, both in the absence and presence of Cyt-B, indicating that this chemical does not interfere with NP uptake. Dose-dependent increases in MN rates were observed in CBMN test after co-treatment. However, FCMN assay only showed a positive response when Cyt-B was added simultaneously with TiO2 NP, suggesting that Cyt-B might alter CBMN assay results. No differences were observed in the comparisons between the treatment options assessed, suggesting they are not adequate alternatives to avoid Cyt-B interference in the specific conditions tested.

Potassium bromate as positive assay control for the Fpg-modified comet assay.

The comet assay is a popular assay in biomonitoring studies. DNA strand breaks (or unspecific DNA lesions) are measured using the standard comet assay. Oxidative stress-generated DNA lesions can be measured by employing DNA repair enzymes to recognise oxidatively damaged DNA. Unfortunately, there has been a tendency to fail to report results from assay controls (or maybe even not to employ assay controls). We believe this might have been due to uncertainty as to what really constitutes a positive control. It should go without saying that a biomonitoring study cannot have a positive control group as it is unethical to expose healthy humans to DNA damaging (and thus potentially carcinogenic) agents. However, it is possible to include assay controls in the analysis (here meant as a cryopreserved sample of cells i.e. included in each experiment as a reference sample). In the present report we tested potassium bromate (KBrO3) as a positive comet assay control for the formamidopyrimidine DNA glycosylase (Fpg)-modified comet assay. Ten laboratories used the same procedure for treatment of monocytic THP-1 cells with KBrO3 (0.5, 1.5 and 4.5 mM for 1 h at 37°C) and subsequent cryopreservation. Results from one laboratory were excluded in the statistical analysis because of technical issues in the Fpg-modified comet assay. All other laboratories found a concentration-response relationship in cryopreserved samples (regression coefficients from 0.80 to 0.98), although with different slopes ranging from 1.25 to 11.9 Fpg-sensitive sites (%DNA in tail) per 1 mM KBrO3. Our results demonstrate that KBrO3 is a suitable positive comet assay control.

Expanded usage of the Challenge-Comet assay as a DNA repair biomarker in human populations: protocols for fresh and cryopreserved blood samples, and for different challenge agents.

Deficiencies in DNA damage response and repair (DDRR) can cause serious pathological outcomes; therefore, having an ability to determine individual DDRR would enhance specificities in health risk assessment and in determining individual's response to cancer therapies. However, most methods for evaluating DDRR are not fully appropriate for population studies. The Challenge-Comet assay has gained acceptance for this purpose. The assay has traditionally used X-rays as challenge agent and isolated peripheral blood mononuclear cells (PBMC) as cell specimen. To enhance the usefulness of the assay, the objectives of this investigation were to use differently processed blood samples, to employ other challenge agents with different mechanisms of induction of DNA damage/repair, and to generate protocols for detecting different DDRR capacities. Fresh and frozen blood samples were challenged with bleomycin, methyl methanesulfonate (MMS) and ultraviolet light. Significant induction of damage after all treatments, and progressive and time-dependent DDRR were observed. No significant differences were obtained in the DDRR capacities of fresh or frozen whole blood samples as compared to PBMC, except that fresh blood samples showed higher MMS-induced DDRR capacity than PBMC. Results from this study show that the Challenge-Comet assay can be used as routine biomarker of DDRR capacity in human biomonitoring studies, and that whole blood is also a useful biomatrix for this assay. The collected data allow us to recommend different protocols for the Challenge-Comet assay which are useful for evaluating DDRR capacities in several key DNA repair pathways. Consequently, the usefulness of the Challenge-Comet assay can be greatly expanded.

Medication use in older patients and age-blind approach: narrative literature review (insufficient evidence on the efficacy and safety of drugs in older age, frequent use of PIMs and polypharmacy, and underuse of highly beneficial nonpharmacological strategies).

INTRODUCTION: The importance of rational drug therapy is increasing with the aging of the population. Since one of the main reasons for inappropriate drug prescribing is also the "age-blind" approach, which results in ageist practices, this narrative literature review focuses on the description of the main barriers related to insufficient individualization of drug regimens associated with such age-blind approaches. METHODOLOGY: A narrative literature review using the PubMed, WoS, Embase, and Scopus databases was conducted by the EU COST Action IS1402. Experts in different scientific fields from six countries (the Czech Republic, Spain, Portugal, Hungary, Serbia, and Turkey) worked in four specific areas: (1) underrepresentation of older adults in clinical trials and clinical and ethical consequences; (2) insufficient consideration of age-related changes and geriatric frailty in the evaluation of the therapeutic value of drugs; (3) frequent prescribing of potentially inappropriate medications (PIMs); and (4) frequent underuse of highly beneficial nonpharmacological strategies (e.g., exercise). RESULTS: Older patients are underrepresented in clinical trials. Therefore, rigorous observational geriatric research is needed in order to obtain evidence on the real efficacy and safety of frequently used drugs, and e.g. developed geriatric scales and frailty indexes for claims databases should help to stimulate such research. The use of PIMs, unfortunately, is still highly prevalent in Europe: 22.6% in community-dwelling older patients and 49.0% in institutionalized older adults. Specific tests to detect the majority of age-related pharmacological changes are usually not available in everyday clinical practice, which limits the estimation of drug risks and possibilities to individualize drug therapy in geriatric patients before drug prescription. Moreover, the role of some nonpharmacological  strategies is highly underestimated in older adults in contrast to frequent use of polypharmacy. Among nonpharmacological strategies, particularly physical exercise was highly effective in reducing functional decline, frailty, and the risk of falls in the majority of clinical studies. CONCLUSION: Several regulatory and clinical barriers contribute to insufficient knowledge on the therapeutic value of drugs in older patients, age-blind approach, and inappropriate prescribing. New clinical and observational research is needed, including data on comprehensive geriatric assessment and frailty, to document the real efficacy and safety of frequently used medications.

Occupational exposure to formaldehyde and early biomarkers of cancer risk, immunotoxicity and susceptibility.

Formaldehyde (FA) is a high-volume production chemical manufactured worldwide to which many people are exposed to both environmentally and occupationally. FA was recently reclassified as a human carcinogen. Several epidemiological studies have revealed an increased risk of cancer development among workers exposed to FA. Although FA genotoxicity was confirmed in a variety of experimental systems, data from human studies are conflicting. The aim of the present study was to evaluate the occupational exposure to FA in a multistage approach relating the exposure with different biomarkers (dose and effect) and individual susceptibility. Air monitoring was performed to estimate the level of exposure to FA during shift work. Eighty-five workers from hospital anatomy-pathology laboratories exposed to FA and 87 controls were tested for cytogenetic alterations in lymphocytes (micronucleus, MN; sister-chromatid exchange, SCE) and T-cell receptor (TCR) mutation assay. The frequency of MN in exfoliated buccal cells, a first contact tissue was also assessed. Percentages of different lymphocyte subpopulations were selected as immunotoxicity biomarkers. The level of formic acid in urine was investigated as a potential biomarker of internal dose. The effects of polymorphic genes of xenobiotic metabolising enzymes and DNA repair enzymes on the endpoints studied were determined. The mean level of FA exposure was 0.38 ±â€¯0.03 ppm. MN (in lymphocytes and buccal cells) and SCE were significantly increased in FA-exposed workers compared to controls. MN frequency positively correlated with FA levels of exposure and duration. Significant alterations in the percentage of T cytotoxic lymphocytes, NK cells and B lymphocytes were found between groups. Polymorphisms in CYP2E1, GSTP1 and FANCA genes were associated with increased genetic damage in FA-exposed subjects. The obtained information may provide new important data to be used by health and safety care programs and by governmental agencies responsible for setting the acceptable levels for occupational exposure to FA.

Serum cortisol but not oxidative stress biomarkers are related to frailty: results of a cross-sectional study in Spanish older adults.

Frailty is a multidimensional geriatric syndrome of loss of reserves and increased vulnerability to negative health outcomes. Cortisol, the major hormone of the hypothalamic pituitary adrenal (HPA) axis, and oxidative stress may be influenced by multiple endogenous and environmental factors throughout the lifespan, triggering changes in organism functioning. Association of elevated levels of cortisol and oxidative stress biomarkers with aging and several age-related diseases is well documented. However, the possible role of these factors on frailty status in older adults has not been extensively studied. Hence, the aim of this study was to conduct a cross-sectional study in 252 older adults (≥65 years old) classified according to their frailty status. Plasma cortisol and biomarkers related to oxidative stress including reactive oxygen/nitrogen species, oxidative DNA damage, and total antioxidant capacity were determined in non-frail, pre-frail, and frail subjects. Results showed significantly increasing cortisol concentrations with frailty burden, but no marked association between any oxidative stress biomarker and frailty status. In addition, dependence on activities of daily living and 10-year mortality risk were also correlated with elevated cortisol levels. Current results support the hypothesis that age-related HPA axis dysregulation is associated with frailty status, although further research is necessary to establish the role of cortisol in the pathophysiology of frailty.

Cellular and Molecular Toxicity of Iron Oxide Nanoparticles.

Iron oxide nanoparticles (ION) have attracted much attention because of their particular physico-chemical properties, including superparamagnetism. These features make them suitable for many purposes and several interesting biomedical applications, such as to increase contrast in magnetic resonance imaging (MRI), as drug delivery systems and as hyperthermia agents. However, they have also shown to be easily accumulated in diverse tissues and induce toxicity at different levels. This chapter reviews the different cellular and molecular effects induced by ION reported from in vitro studies with human and non-human cell lines. Those effects are mainly dependent on ION type and concentration, time of exposure, presence and nature of coating, and cell type evaluated. They include decreases in viability, plasmatic membrane disruption, oxidative damage, mitochondrial alterations, cell cycle impairments, cytoskeleton disruption, cell death, and alterations in cell motility, and in cell integrity. Despite these negative effects, the numerous advantages of ION together with their promising applications in biomedicine, make it necessary to clearly define their toxicity in order to discard potential health risks and to reach optimal benefits of their use.

Immune biomarkers in older adults: Role of physical activity.

Aging is associated with a decline in the normal functioning of the immune system. Several studies described the relationship between immunological alterations, including immunosenescence and inflammation, and aging or age-related outcomes, such as sarcopenia, depression, and neurodegenerative disorders. Physical activity is known to improve muscle function and to exert a number of benefits on older adult health, including reduced risk for heart and metabolic system chronic diseases. However, the positive influence of physical activity on the immune system has not been elucidated. In order to shed light on the role of physical activity in immune responses of older individuals, a number of immunological parameters comprising % lymphocyte subsets (CD3+, CD4+, CD8+, CD19+, and CD16+56+) and serum levels of neopterin and tryptophan metabolism products were evaluated in peripheral blood samples of older adults performing normal (N = 170) or reduced (N = 89) physical activity. In addition, the potential influence of other clinical and epidemiological factors was also considered. Results showed that subjects with reduced physical activity displayed significantly higher levels of CD4+/CD8+ ratio, kynurenine/tryptophan ratio, and serum neopterin, along with lower %CD19+ cells and tryptophan concentrations. Further, some immunological biomarkers were associated with cognitive impairment and functional status. These data contribute to reinforce the postulation that physical activity supports healthy aging, particularly by helping to protect the immunological system from aging-related changes.

Effects of exposure to oil spills on human health: Updated review.

Oil spills may involve health risks for people participating in the cleanup operations and coastal inhabitants, given the toxicological properties of the oil components. In spite of this, only after a few major oil spills (crude oil or fuel oil no. 6) have studies on effects of exposure to diverse aspects of human health been performed. Previously, Aguilera et al. (2010) examined all documents published to that date dealing with any type of human health outcome in populations exposed to oil spills. The aim of the present review was to compile all new information available and determine whether evidence reported supports the existence of an association between exposure and adverse human health risks. Studies were classified in three groups according to type of health outcome addressed: (i) effects on mental health, (ii) physical/physiological effects, and (iii) genotoxic, immunotoxic, and endocrine toxicity. New studies published on oil-spill-exposed populations-coastal residents in the vicinity of the spills or participants in cleanup operations-provide additional support to previous evidence on adverse health effects related to exposure regarding different parameters in all three categories considered. Some of the observed effects even indicated that several symptoms may persist for some years after exposure. Hence, (1) health protection in these individuals should be a matter of concern; and (2) health risk assessment needs to be carried out not only at the time of exposure but also for prolong periods following exposure, to enable early detection of any potential exposure-related harmful effects.