Cytogenetic alterations in lymphocytes of Alzheimer's disease and Parkinson's disease patients

Aneuploidy is Linked to Neurological Phenotypes Through Oxidative Stress

Aneuploidy, having an aberrant genome, is gaining increasing attention in neurodegenerative diseases. It gives rise to proteotoxic stress as well as a stereotypical oxidative shift which makes these cells sensitive to internal and environmental stresses. A growing body of research from numerous laboratories suggests that many neurodegenerative disorders, especially Alzheimer's disease and frontotemporal dementia, are characterised by neuronal aneuploidy and the ensuing apoptosis, which may contribute to neuronal loss. Using Drosophila as a model, we investigated the effect of induced aneuploidy in GABAergic neurons. We found an increased proportion of aneuploidy due to Mad2 depletion in the third-instar larval brain and increased cell death. Depletion of Mad2 in GABAergic neurons also gave a defective climbing and seizure phenotype. Feeding animals an antioxidant rescued the climbing and seizure phenotype. These findings suggest that increased aneuploidy leads to higher oxidative stress in GABAergic neurons which causes cell death, climbing defects, and seizure phenotype. Antioxidant feeding represents a potential therapy to reduce the aneuploidy-driven neurological phenotype.

Telomere length and micronuclei trajectories in APP/PS1 mouse model of Alzheimer's disease: Correlating with cognitive impairment and brain amyloidosis in a sexually dimorphic manner

Although studies have demonstrated that genome instability is accumulated in patients with Alzheimer's disease (AD), the specific types of genome instability linked to AD pathogenesis remain poorly understood. Here, we report the first characterization of the age- and sex-related trajectories of telomere length (TL) and micronuclei in APP/PS1 mice model and wild-type (WT) controls (C57BL/6). TL was measured in brain (prefrontal cortex, cerebellum, pituitary gland, and hippocampus), colon and skin, and MN was measured in bone marrow in 6- to 14-month-old mice. Variation in TL was attributable to tissue type, age, genotype and, to a lesser extent, sex. Compared to WT, APP/PS1 had a significantly shorter baseline TL across all examined tissues. TL was inversely associated with age in both genotypes and TL shortening was accelerated in brain of APP/PS1. Age-related increase of micronuclei was observed in both genotypes but was accelerated in APP/PS1. We integrated TL and micronuclei data with data on cognition performance and brain amyloidosis. TL and micronuclei were linearly correlated with cognition performance or Aβ40 and Aβ42 levels in both genotypes but to a greater extent in APP/PS1. These associations in APP/PS1 mice were dominantly driven by females. Together, our findings provide foundational knowledge to infer the TL and micronuclei trajectories in APP/PS1 mice during disease progression, and strongly support that TL attrition and micronucleation are tightly associated with AD pathogenesis in a female-biased manner.

Presenilin-1, mutated in familial Alzheimer's disease, maintains genome stability via a γ-secretase dependent way

Mutations in Presenilin-1 (PS1) account for over 80 % mutations linked to familial Alzheimer's disease (AD). However, the mechanisms of action of PS1 mutations in causing familial AD are not fully understood, limiting opportunities to develop targeted disease-modifying therapies for individuals carrying PS1 mutation. To gain more comprehensive insights into the impact of PS1 mutations on genome stability, we knocked down PS1 in SH-SY5Y, HMC3 and A549 cells. This revealed that PS1 knockdown (KD) dramatically induces genome instability (GIN) in all cell types, as indicated by the increased incidence of micronuclei, nucleoplasmic bridges and/or nuclear buds. Although amyloid β (Aβ) was able to induce GIN, PS1-KD was associated with decreased expression of Aβ in SH-SY5Y cells, suggesting Aβ is not the primary cause of GIN in PS1-KD cells. In contrast, inhibiting the PS1 γ-secretase activity by DAPT recapitulated GIN phenotype as seen in PS1-KD cells, indicating that the induction of GIN following PS1 KD can be attributed to the loss of γ-secretase activity. PS1 KD or γ-secretase inhibition markedly sensitizes SH-SY5Y to the genotoxicity of mitomycin C. Interestingly, overexpression of the wildtype PS1 dramatically increased GIN in SH-SY5Y. Collectively, our study demonstrates the potential of PS1 and its γ-secretase activity in maintaining genome stability, highlighting a novel potential link between PS1 loss-of-function or gain-of-function mutations and familial AD through GIN. Several mechanisms by which GIN induced by PS1 dys-expression may contribute to AD are discussed.

"Micronuclei and Disease" special issue: Aims, scope, and synthesis of outcomes

The purpose of the "Micronuclei and Disease" special issue (SI) is to: (i) Determine the level of evidence for association of micronuclei (MN), a biomarker of numerical and structural chromosomal aberrations, with risk of specific diseases in humans; (ii) Define plausible mechanisms that explain association of MN with each disease; (iii) Identify knowledge gaps and research needed to translate MN assays into clinical practice. The "MN and Disease" SI includes 14 papers. The first is a review of mechanisms of MN formation and their consequences in humans. 11 papers are systematic reviews and/or meta-analyses of the association of MN with reproduction, child health, inflammation, auto-immune disease, glycation, metabolic diseases, chronic kidney disease, cardiovascular disease, eleven common cancers, ageing and frailty. The penultimate paper focuses on effect of interventions on MN frequency in the elderly. A road map for translation of MN data into clinical practice is the topic of the final paper. The majority of reviewed studies were case-control studies in which the ratio of mean MN frequency in disease cases relative to controls, i.e. the mean ratio (MR), was calculated. The mean of these MR values, estimated by meta-analyses, for lymphocyte and buccal cell MN in non-cancer diseases were 2.3 and 3.6 respectively, and for cancers they were 1.7 and 2.6 respectively. The highest MR values were observed in studies of cancer cases in which MN were measured in the same tissue as the tumour (MR = 4.9-10.8). This special issue is an important milestone in the evidence supporting MN as a reliable genomic biomarker of developmental and degenerative disease risk. These advances, together with results from prospective cohort studies, are helping to identify diseases in which MN assays can be practically employed in the clinical setting to better identify high risk patients and to prioritise them for preventive therapy.

Combined markers for predicting cognitive deficit in patients with Alzheimer’s disease

Background

Alzheimer’s disease (AD) is the most widely recognized type of dementia. It is associated with cell cycle abnormalities including genomic instability and increased micronuclei (MNi) which usually evolve many years before the appearance of the clinical manifestations. Digital electroencephalogram (EEG) has a role in perceiving brain changes in dementia and in early detection of cognitive decline. This study aimed to assess the competency of using neurophysiological markers including absolute power of alpha waves and a cytogenetic marker which comprises scoring of MNi as a step toward early and preclinical diagnosis of AD. The study was conducted on 27 subjects; they were 15 patients diagnosed as sporadic AD and a group of 12 age and sex-matched controls. All subjects were subjected to Mini-Mental State Examination (MMSE), conventional EEG, digital EEG, and cytokinesis-block micronucleus assay (CBMN) in peripheral blood lymphocytes.

Results

Conventional EEG showed a normal background activity with no abnormal epileptogenic discharges in both groups. Digital EEG showed significant reduction of the absolute power of alpha waves for AD patients as compared to the control group (P < 0.0001). Score of MNi showed statistical significant difference between the two groups (P < 0.0001). By linking scores of both cognitive state using MMSE and MNi among the group of patients, a significant negative correlation was detected (r = −0.6066). The correlations between cognitive state and the absolute power of alpha wave among the patients revealed a positive correlation (r = 0.2235).

Conclusions

The combination of both cytogenetic and neurophysiological markers can be beneficial for early detection of cognitive decline and may lead to preclinical identification of individuals at increased risk for AD, where at this stage treatment is constructive. The negative correlation between the scores of MNi and MMSE is suggestive for the impact of genomic instability on the cognitive state.

CGAS is a micronucleophagy receptor for the clearance of micronuclei

Micronuclei are constantly considered as a marker of genome instability and very recently found to be a trigger of innate immune responses. An increased frequency of micronuclei is associated with many diseases, but the mechanism underlying the regulation of micronuclei homeostasis remains largely unknown. Here, we report that CGAS (cyclic GMP-AMP synthase), a known regulator of DNA sensing and DNA repair, reduces the abundance of micronuclei under genotoxic stress in an autophagy-dependent manner. CGAS accumulates in the autophagic machinery and directly interacts with MAP1LC3B/LC3B in a manner dependent upon its MAP1LC3-interacting region (LIR). Importantly, the interaction is essential for MAP1LC3 recruitment to micronuclei and subsequent clearance of micronuclei via autophagy (micronucleophagy) in response to genotoxic stress. Moreover, in contrast to its DNA sensing function to activate micronuclei-driven inflammation, CGAS-mediated micronucleophagy blunts the production of cyclic GMP-AMP (cGAMP) induced by genotoxic stress. We therefore conclude that CGAS is a receptor for the selective autophagic clearance of micronuclei and uncovered an unprecedented role of CGAS in micronuclei homeostasis to dampen innate immune surveillance.

Abbreviations: ATG: autophagy-related; CGAS: cyclic GMP-AMP synthase; CQ: chloroquine; GABARAP: GABA type A receptor-associated protein; GFP: green fluorescent protein; LAMP1: lysosomal associated membrane protein 1; LAMP2: lysosomal associated membrane protein 2; LIR, MAP1LC3-interacting region; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; NDZ: nocodazole; STING1: stimulator of interferon response cGAMP interactor 1

"Amyloid-beta accumulation cycle" as a prevention and/or therapy target for Alzheimer's disease

The cell cycle and its regulators are validated targets for cancer drugs. Reagents that target cells in a specific cell cycle phase (e.g., antimitotics or DNA synthesis inhibitors/replication stress inducers) have demonstrated success as broad-spectrum anticancer drugs. Cyclin-dependent kinases (CDKs) are drivers of cell cycle transitions. A CDK inhibitor, flavopiridol/alvocidib, is an FDA-approved drug for acute myeloid leukemia. Alzheimer's disease (AD) is another serious issue in contemporary medicine. The cause of AD remains elusive, although a critical role of latent amyloid-beta accumulation has emerged. Existing AD drug research and development targets include amyloid, amyloid metabolism/catabolism, tau, inflammation, cholesterol, the cholinergic system, and other neurotransmitters. However, none have been validated as therapeutically effective targets. Recent reports from AD-omics and preclinical animal models provided data supporting the long-standing notion that cell cycle progression and/or mitosis may be a valid target for AD prevention and/or therapy. This review will summarize the recent developments in AD research: (a) Mitotic re-entry, leading to the "amyloid-beta accumulation cycle," may be a prerequisite for amyloid-beta accumulation and AD pathology development; (b) AD-associated pathogens can cause cell cycle errors; (c) thirteen among 37 human AD genetic risk genes may be functionally involved in the cell cycle and/or mitosis; and (d) preclinical AD mouse models treated with CDK inhibitor showed improvements in cognitive/behavioral symptoms. If the "amyloid-beta accumulation cycle is an AD drug target" concept is proven, repurposing of cancer drugs may emerge as a new, fast-track approach for AD management in the clinic setting.

Aging-related changes in fluid intelligence, muscle and adipose mass, and sex-specific immunologic mediation: A longitudinal UK Biobank study

BACKGROUND

Obesity in midlife and early late-life is associated with worse normal cognitive aging. Dual-energy X-ray absorptiometry (DEXA) suggests that visceral adipose mass (VAM) plays a predominant role, whereas non-visceral adipose mass (NVAM) and lean muscle mass (LMM) have shown conflicting relationships. It is unknown how longitudinal, cognitive changes in age-sensitive domains like fluid intelligence (FI) correspond to VAM, NVAM, and LMM in women and men. Furthermore, changes over time in blood leukocyte sub-populations may partially or fully account for sex-specific associations.

METHODS

Data on 4431 late middle-aged, cognitively unimpaired adults (mean = 64.5 y) was obtained from the UK Biobank prospective cohort across 22 centers. FI scores, blood leukocyte counts, and covariates (age, social class, education) were measured at three 2-year intervals over 6 years. DEXA collection overlapped with these intervals. Sex-stratified growth curves, structural equations, and Preacher-Hayes mediation were used to estimate direct and indirect effects. β-weights were standardized.

RESULTS

More LMM predicted gains in FI scores among women (β = 0.130, p < .001) and men (β = 0.089, p < .001). Conversely, more VAM and NVAM independently predicted FI decline equally among sexes (e.g., NVAM: women: β = -0.082, p < .001; men: β = -0.076, p < .001). Among women, FI associations were fully mediated by higher eosinophil counts via VAM (λ = 30.8%, p = .028) and lower lymphocyte counts via LMM (λ = 69.2%, p = .021). Among men, FI associations were partially mediated by lower basophils counts via LMM (λ = 4.5%, p = .042) and higher counts via VAM (λ = 50%, p = .037).

CONCLUSION

The proportion of LMM and VAM equally influenced male FI changes over 6 years, whereas higher LMM among women appeared to more strongly influence. FI changes. Leukocyte counts strongly mediated VAM- and LMM-related FI changes in a sex-specific manner, but not for NVAM. For clinical translation, exercise studies in older adults may benefit from assessing sex-specific values of DEXA-based tissue mass, FI, and leukocyte sub-populations to gauge potential cognitive benefits of less VAM and more LMM.

The molecular origins and pathophysiological consequences of micronuclei: New insights into an age-old problem

Micronuclei (MN), the small nucleus-like bodies separated from the primary nucleus, can exist in cells with numerical and/or structural chromosomal aberrations in apparently normal tissues and more so in tumors in humans. While MN have been observed for over 100 years, they were merely and constantly considered as passive indicators of chromosome instability (CIN) for a long time. Relatively little is known about the molecular origins and biological consequences of MN. Rapid technological advances are helping to close these gaps. Very recent studies provide exciting evidence that MN act as key platform for chromothripsis and a trigger of innate immune response, suggesting that MN could affect cellular functions by both genetic and nongenetic means. These previously unappreciated findings have reawakened widespread interests in MN. In this review, the diverse mechanisms leading to MN generation and the complex fate profiles of MN are discussed, together with the evidence for their contribution to CIN, inflammation, senescence and cell death. Moreover, we put this knowledge together into a speculative perspective on how MN may be responsible for cancer development and how their presence may influence the choice of treatment. We suggest that the heterogeneous responses to MN may function physiological to ensure the arrestment, elimination and immune clearance of damaged cells, but pathologically, may enable the survival and oncogenic transformation of cells bearing CIN. These insights not only underscore the complexity of MN biology, but also raise a host of new questions and provide fertile ground for future research.

Association Between Inherited Thrombophilia in Pregnancy and Micronucleus Frequency in Peripheral Blood Lymphocytes

The aim of this study was to determine possible predictors of an increased frequency of micronucleus (MN) and the impact of thrombophilia on the chromosomal instability in peripheral blood lymphocytes (PBL) of pregnant women in their first trimester. This study was designed as a case-control study on 74 pregnant women. It was performed in the gestational age of 11 to 14 weeks, when blood samples were collected and incubated for 72 hours. The individual MN frequency in PBL was measured by cytokinesis-block micronucleus (CBMN) assay. Women were grouped in control group [≤4 MN/1000 binucleated (BN) cells] and case group (>4 MN/1000 BN cells). Potential mutagenic effects of exogenous/endogenous factors in pregnant women were analyzed. By analyzing the given results, it can be concluded that pregnant women with thrombophilia have 26.69-times more chance of having a frequency of >4 MN/1000 BN than pregnant women with no thrombophilia. Our research was primarily aimed at showing that the presence of thrombophilia was a statistically important predictor of an increased MN frequency in pregnant women and it can predict about one-third of the total variance in MN frequency in the studied population.

Generation of Advanced Glycation End-Products (AGEs) by glycoxidation mediated by copper and ROS in a human serum albumin (HSA) model peptide: reaction mechanism and damage in motor neuron cells

Glucose, in the presence of reactive oxygen species (ROS), acts as an as an oxidative agent and drives deleterious processes in Diabetes Mellitus. We have studied the mechanism and the toxicological effects of glucose-dependent glycoxidation reactions driven by copper and ROS, using a model peptide based on the exposed sequence of Human Serum Albumin (HSA) and containing a lysine residue susceptible to copper complexation. The main products of these reactions are Advanced Glycation End-products (AGEs). Carboxymethyl lysine and pyrraline condensed on the model peptide, generating a Modified Peptide (MP). These products were isolated, purified, and tested on cultured motor neuron cells. We observed DNA damage, enhancement of membrane roughness, and formation of domes. We evaluated nuclear abnormalities by the cytokinesis-blocked micronucleus assay and we measured cytostatic and cytotoxic effects, chromosomal breakage, nuclear abnormalities, and cell death. AGEs formed by glycoxidation caused large micronucleus aberrations, apoptosis, and large-scale nuclear abnormalities, even at low concentrations.

Biomonitoring of Buccal Mucosa Cells in Chronic Smokers and Nonsmokers

Background

Despite the well-known presence of carcinogens in tobacco smoke, results in the scientific literature linking smoking habits to micronuclei frequency are rather controversial.

Aim

The study was conducted to compare and evaluate the frequency of micronuclei in chronic smokers and nonsmokers in relation to habit history, personal history, and other related factors like occupation, exposure to radiation, etc.

Materials and methods

A total of 50 randomly selected male subjects were included in the study. Case and control groups (smokers and nonsmokers respectively) comprised 25 subjects each (mean age in controls = 38.24 ± 2.7; mean age in smokers = 39.32 ± 3.8).

Results and conclusion

There was a significant relation between tobacco consumption and frequency of micronucleated cells (p = 0.05) and between radiation exposure and presence of micronuclei (p = 0.05) in controls and subjects. Within the smokers group, left cheek scrapings showed higher count (p = 0.05; significant) for the micronucleated cells as compared with right cheek scrapings.

Clinical significance

In this study, an attempt was made to estimate the cytogenetic damage in oral mucosa in people habituated to smoking beedi. Though tobacco plays an important role in micronuclei generation, other factors like ionizing radiation and personal habits also contribute to micronuclei frequency. Site of smear, sample size, nuclear specific stain usage are some of the contributing factors. In addition, cytogenetic alterations like karyolysis, pyknosis, etc., can be included in future studies to increase the specificity.

How to cite this article

Sarpal RS, Taneja N, Shergill NK, Ravindra SV. Biomonitoring of Buccal Mucosa Cells in Chronic Smokers and Nonsmokers. World J Dent 2016;7(4):189-194.

Chromosomal DNA damage in APOE ɛ4 carriers and noncarriers does not appear to be different

DNA damage may play a key role in promoting disease-onset and accelerated disease progression in Alzheimer's disease (AD) by increasing the rates of neuronal cell death. The ɛ4 allele of the APOE gene is the best characterised genetic risk factor for AD, however, it is unknown if APOE ɛ4 carriers exhibit increased levels of DNA damage which may contribute to increased AD risk. 175 healthy participants (aged 34-67 years old) from South Australia were recruited into the study and provided a single blood sample for the isolation of peripheral blood lymphocytes, APOE genotyping and lymphocyte chromosomal DNA damage analysis using the Cytokinesis-Block micronucleus cytome (CBMN-Cyt) assay with the micronucleus index being the primary outcome measure. When compared to non-APOE ɛ4 carriers, APOE ɛ4 carriers did not exhibit altered rates of i) cell division, represented by the nuclear division index (NDI, P = 0.372), ii) cell death as represented by apoptotic (P = 0.457) and necrotic (P = 0.393) frequencies and iii) chromosomal DNA damage as indicated by the number of micronuclei (MNi, P = 0.795), nucleoplasmic bridges (NPBs, P = 0.221) or nuclear buds (NBUDs, P = 0.293) scored in binucleated cells. In conclusion, although we and others have previously shown that rates of chromosomal DNA damage measured using the CBMN-Cyt assay are elevated in individuals with cognitive impairment, in this South Australian cohort the frequency of genome instability is not substantially influenced by the presence of the APOE ɛ4 allele.

Micronucleus frequency in peripheral blood lymphocytes and frailty status in elderly. A lack of association with clinical features

Frailty is a condition of vulnerability that carries an increased risk of poor outcome in elder adults. Frail individuals show fatigue, weight loss, muscle weakness, and a reduced physical function, and are known to frequently experience disability, social isolation, and institutionalization. Identifying frail people is a critical step for geriatricians to provide timely geriatric care and, eventually, to improve the quality of life in elderly. The aim of the present study is to investigate the association between frailty status and micronucleus (MN) frequency, a known marker of genomic instability, in a sample of elder adults. Several clinical features were evaluated and their possible association with MN frequency was tested. Criteria proposed by Fried were used to identify frail subjects. Overall, 180 elder adults entered the study, 93 of them (51.7%) frail. No association between MN frequency and frailty status was found under the specific conditions tested in this study (mean ratio=1.06; 95% CI 0.96-1.18). The inclusion of MN frequency in the Fried's frailty scale minimally improved the classification of study subjects according to the multidimensional prognostic index (MPI). The presence of genomic instability in the ageing process and in most chronic diseases, demands further investigation on this issue.

DNA damage in neurodegenerative diseases

Following the observation of increased oxidative DNA damage in nuclear and mitochondrial DNA extracted from post-mortem brain regions of patients affected by neurodegenerative diseases, the last years of the previous century and the first decade of the present one have been largely dedicated to the search of markers of DNA damage in neuronal samples and peripheral tissues of patients in early, intermediate or late stages of neurodegeneration. Those studies allowed to demonstrate that oxidative DNA damage is one of the earliest detectable events in neurodegeneration, but also revealed cytogenetic damage in neurodegenerative conditions, such as for example a tendency towards chromosome 21 malsegregation in Alzheimer's disease. As it happens for many neurodegenerative risk factors the question of whether DNA damage is cause or consequence of the neurodegenerative process is still open, and probably both is true. The research interest in markers of oxidative stress was shifted, in recent years, towards the search of epigenetic biomarkers of neurodegenerative disorders, following the accumulating evidence of a substantial contribution of epigenetic mechanisms to learning, memory processes, behavioural disorders and neurodegeneration. Increasing evidence is however linking DNA damage and repair with epigenetic phenomena, thereby opening the way to a very attractive and timely research topic in neurodegenerative diseases. We will address those issues in the context of Alzheimer's disease, Parkinson's disease, and Amyotrophic Lateral Sclerosis, which represent three of the most common neurodegenerative pathologies in humans.

Biomarkers of Alzheimer's disease risk in peripheral tissues; focus on buccal cells

Alzheimer's disease (AD) is a progressive degenerative disorder of the brain and is the most common form of dementia. To-date no simple, inexpensive and minimally invasive procedure is available to confirm with certainty the early diagnosis of AD prior to the manifestations of symptoms characteristic of the disease. Therefore, if population screening of individuals is to be performed, more suitable, easily accessible tissues would need to be used for a diagnostic test that would identify those who exhibit cellular pathology indicative of mild cognitive impairment (MCI) and AD risk so that they can be prioritized for primary prevention. This need for minimally invasive tests could be achieved by targeting surrogate tissues, since it is now well recognized that AD is not only a disorder restricted to pathology and biomarkers within the brain. Human buccal cells for instance are accessible in a minimally invasive manner, and exhibit cytological and nuclear morphologies that may be indicative of accelerated ageing or neurodegenerative disorders such as AD. However, to our knowledge there is no review available in the literature covering the biology of buccal cells and their applications in AD biomarker research. Therefore, the aim of this review is to summarize some of the main findings of biomarkers reported for AD in peripheral tissues, with a further focus on the rationale for the use of the buccal mucosa (BM) for biomarkers of AD and the evidence to date of changes exhibited in buccal cells with AD.

Genome instability biomarkers and blood micronutrient risk profiles associated with mild cognitive impairment and Alzheimer's disease

Successful maintenance of metabolic systems relating to accurate DNA replication and repair is critical for optimal lifelong human health. Should this homeostatic balance become impaired, genomic instability events can arise, compromising the integrity of the genome, which may result in gene expression and human disease. Both genome instability and micronutrient imbalance have been identified and implicated in diseases associated with accelerated ageing which potentially leads to an increased risk for the future development of clinically defined neurodegenerative disorders. Cognitive decline leading to the clinical diagnosis of mild cognitive impairment (MCI) has been shown to predict an increased risk in later life of developing Alzheimer's disease (AD). Knowledge on the impact of dietary factors in relation to MCI and AD risk is improving but incomplete; in particular the role of nutrient combinations (i.e. nutriomes) has not been thoroughly investigated. Currently, there is a need for preventative strategies as well as the identification of robust and reproducible diagnostic biomarkers that will allow identification of those individuals with increased risk for neurodegenerative diseases. Growing evidence suggests cells originating from different somatic tissues derived from individuals that have been clinically diagnosed with neurodegenerative disorders exhibit elevated frequencies of DNA damage compared to tissues of cognitively normal individuals which could be due to malnutrition. The objective of this review is to discuss current evidence and identify knowledge gaps relating to genome instability biomarkers and blood micronutrient profiles from human studies of MCI and AD that may be specific to and contribute to the increased risk of these diseases. This is a vital step in order to create research strategies for the future development of diagnostics that are indicative of dementia risk and to inform preventative therapies.

Cognitive impairment, genomic instability and trace elements

Cognitive impairments are often related to aging and micronutrient deficiencies. Various essential micronutrients in the diet are involved in age-altered biological functions such as, zinc, copper, iron, and selenium that play pivotal roles either in maintaining and reinforcing the antioxidant performances or in affecting the complex network of genes (nutrigenomic approach) involved in encoding proteins for biological functions. Genomic stability is one of the leading causes of cognitive decline and deficiencies or excess in trace elements are two of the factors relating to it. In this review, we report and discuss the role of micronutrients in cognitive impairment in relation to genomic stability in an aging population. Telomere integrity will also be discussed in relation to aging and cognitive impairment, as well as, the micronutrients related to these events. This review will provide an understanding on how these three aspects can relate with each other and why it is important to keep a homeostasis of micronutrients in relation to healthy aging. Micronutrient deficiencies and aging process can lead to genomic instability.

Chromosomal DNA damage measured using the cytokinesis-block micronucleus cytome assay is significantly associated with cognitive impairment in South Australians

Loss of genome integrity may be associated with increased risk for neurodegenerative disease. The aim of this study was to investigate whether mild cognitive impairment (MCI) or Alzheimer's disease (AD) individuals have increased DNA damage relative to age- and gender- matched controls using the cytokinesis-block micronucleus cytome (CBMN-Cyt) assay. DNA damage was measured as micronuclei (MN), nucleoplasmic bridges (NPB), and nuclear buds (NBUD) in binucleated cells. The assay was performed on blood samples from 80 participants consisting of (i) MCI cases (N = 20) and age- and gender- matched controls (N = 20), and (ii) AD cases (N = 20) and age- and gender- matched controls (N = 20). There was a significant increase in MCI NBUD frequency (P = 0.006) relative to controls, which was also observed in male (P = 0.03) and female (P = 0.04) subgroups. For AD cases, there were no significant differences in assay biomarkers relative to controls. There was a significant negative correlation between Mini Mental State Examination (MMSE) and (i) MN in all controls, (R = -0.3, P = 0.04), and AD cases (R = -0.4, P = 0.03), (ii) NPB in all controls, (R = -0.4, P = 0.006) and AD cases (R = -0.5, P = 0.01), and (iii) NBUD in MCI cases (R = -0.5, P = 0.007) and AD cases (R = -0.7, P = 0.0002). The results suggest that an increase in lymphocyte CBMN-Cyt DNA damage biomarkers may be associated with cognitive decline.

DNA damage in non-communicable diseases: A clinical and epidemiological perspective

Non-communicable diseases (NCDs) are a leading cause of death and disability, representing 63% of the total death number worldwide. A characteristic phenotype of these diseases is the accelerated aging, which is the result of phenomena such as accumulated DNA damage, telomere capping loss and subcellular irreversible/nonrepaired oxidative damage. DNA damage, mostly oxidative, plays a key role in the development of most common NCDs. The present review will gather some of the most relevant knowledge concerning the presence of DNA damage in NCDs focusing on cardiovascular diseases, diabetes, chronic obstructive pulmonary disease, and neurodegenerative disorders, and discussing a selection of papers from the most informative literature. The challenge of comorbidity and the potential offered by new systems approaches for introducing these biomarkers into the clinical decision process will be discussed. Systems Medicine platforms represent the most suitable approach to personalized medicine, enabling to identify new patterns in the pathogenesis, diagnosis and prognosis of chronic diseases.

Effect of docosahexaenoic acid and furan fatty acids on cytokinesis block micronucleus cytome assay biomarkers in astrocytoma cell lines under conditions of oxidative stress

Fatty acids from fish such as docosahexaenoic acid (DHA) are associated with improved brain function, whereas furan fatty acids (FFAs) also found in fish oil at low levels (1%) are thought to have antioxidant properties. Understanding their effects in astrocytes is important as these cells are responsible for maintaining healthy neurons via lipid homeostasis and distribution within the brain, and their decline with aging is a possible cause of dementia. We investigated the cytotoxic and genotoxic effects of DHA and FFA using the cytokinesis-block micronucleus cytome assay in in vitro cultures of U87MG (APOE ɛ3/ɛ3) and U118MG (APOE ɛ2/ɛ4) astrocytoma cell lines with and without a hydrogen peroxide (H2O2, 100 µM) challenge. U118MG was found to be more sensitive to the cytostatic, cytotoxic (i.e., apoptosis), and DNA damaging effects [micronuclei (MNi), nucleoplasmic bridges (NPBs), and nuclear buds (NBUDs)] of H2O2 (P < 0.01 and P < 0.001) when compared with U87MG. DHA at 100 µg/mL significantly affected cytostasis (P < 0.05) and increased DNA damage in the form of NPBs and MNi (P < 0.05) in both cell lines, whereas it decreased necrosis (P = 0.0251) in U87MG. Significant DHA-H2O2 interactions were observed for decreased necrosis (P = 0.0033) and DNA damage biomarkers (P < 0.0001) in the U87MG cell line and increased cytostasis (P < 0.0001) in the U118MG cell line. The effects of FFA also varied between the cell lines, with significant effects observed in decreased cytostasis (P = 0.0022) in the U87MG cell line, whereas increasing cytostasis (P = 0.0144) in the U118MG cell line. Overall, FFA exerted minimal effects on DNA damage biomarkers.

Extracellular amyloid beta 42 causes necrosis, inhibition of nuclear division, and mitotic disruption under both folate deficient and folate replete conditions as measured by the cytokinesis-block micronucleus cytome assay

Alzheimer's disease is associated with accumulation of extracellular beta amyloid peptide 42 (Aβ42) which may induce DNA damage and reduce cellular regenerative potential. These effects may be exacerbated under conditions of folate deficiency. The aim of this study was to investigate whether extracellular Aβ42 induces DNA damage and cell death in human peripheral lymphocytes and whether there is an interactive effect between extracellular Aβ42 and folic acid status. Peripheral blood lymphocytes were cultured in medium under conditions of both low and high folate (20 and 200 nM, respectively) and challenged with either Aβ42 or the physiologically normal form Aβ40 (both at 5, 10, 15 µM). Genome stability and cytotoxicity events were investigated using the cytokinesis-block micronucleus cytome (CBMN-cyt) assay. Outcome measures scored included the nuclear division index (NDI), necrosis, apoptosis, binucleated cells with micronuclei (MN), nucleoplasmic bridges (NPB), and nuclear buds (NBUD) and abnormally shaped nuclei (circular, (CIR) and horse-shoe, (HS) that may be indicative of mitotic disruption. Folic acid deficiency significantly reduced NDI (P < 0.001) and increased all the DNA damage biomarkers (MN, NPB, NBUD, HS, CIR), (P < 0.001). In contrast, exposure to Aβ40 had no impact on CBMN cytome biomarkers but Aβ42 significantly reduced NDI (P < 0.01), increased necrosis (P < 0.05) and frequency of cells with circular nuclei (P < 0.01). There was no evidence of an interaction between Aβ42 and folic acid with respect to CBMN cytome biomarkers. Extracellular Aβ42 appears to have cytotoxic and cytostatic effects but its effect on chromosomal instability appears to be small relative to folate deficiency.

Cellular and molecular mediators of neuroinflammation in the pathogenesis of Parkinson's disease

Neuroinflammation is a host-defense mechanism associated with restoration of normal structure and function of the brain and neutralization of an insult. Increasing neuropathological and biochemical evidence from the brains of individuals with Parkinson's disease (PD) provides strong evidence for activation of neuroinflammatory pathways. Microglia, the resident innate immune cells, may play a major role in the inflammatory process of the diseased brain of patients with PD. Although microglia forms the first line of defense for the neural parenchyma, uncontrolled activation of microglia may directly affect neurons by releasing various molecular mediators such as inflammatory cytokines (tumor necrosis factor-α, interleukin [IL]-6, and IL-1β), nitric oxide, prostaglandin E2, and reactive oxygen and nitrogen species. Moreover, recent studies have reported that activated microglia phagocytose not only damaged cell debris but also intact neighboring cells. This phenomenon further supports their active participation in self-enduring neuronal damage cycles. As the relationship between PD and neuroinflammation is being studied, there is a realization that both cellular and molecular mediators are most likely assisting pathological processes leading to disease progression. Here, we discuss mediators of neuroinflammation, which are known activators released from damaged parenchyma of the brain and result in neuronal degeneration in patients with PD.

Increased frequency of micronuclei in adults with a history of childhood sexual abuse: a discordant monozygotic twin study

BACKGROUND

Childhood sexual abuse (CSA) is a traumatic life event associated with an increased lifetime risk for psychopathology/morbidity. The long-term biological consequences of CSA-elicited stress on chromosomal stability in adults are unknown. The primary aim of this study was to determine if the rate of acquired chromosomal changes, measured using the cytokinesis-block micronucleus assay on stimulated peripheral blood lymphocytes, differs in adult female monozygotic twins discordant for CSA.

METHODS

Monozygotic twin pairs discordant for CSA were identified from a larger population-based sample of female adult twins for whom the experience of CSA was assessed by self-report (51 individuals including a reference sample). Micronuclei (MN) contain chromatin from structurally normal or abnormal chromosomes that are excluded from the daughter nuclei during cell division and serve as a biomarker to assess acquired chromosomal instability.

RESULTS

Female twins exposed to CSA exhibited a 1.63-fold average increase in their frequency of MN compared to their nonexposed genetically identical cotwins (Paired t-test, t₁₆ = 2.65, P = 0.017). No additional effects of familial factors were detected after controlling for the effect of CSA exposure. A significant interaction between CSA history and age was observed, suggesting that the biological effects of CSA on MN formation may be cumulative.

CONCLUSIONS

These data support a direct link between CSA exposure and MN formation measured in adults that is not attributable to genetic or environmental factors shared by siblings. Further research is warranted to understand the biological basis for the observed increase in acquired chromosomal findings in people exposed to CSA and to determine if acquired somatic chromosomal abnormalities/somatic clonal mosaicism might mediate the adult pathology associated with CSA.

Cytoprotective and pro-apoptotic activities of native Australian herbs polyphenolic-rich extracts

Three commercially grown native herbs unique to Australia, Tasmannia pepper leaf (Tasmannia lanceolata R. Br., Winteracea; TPL), anise myrtle (Syzygium anisatum Vickery, Craven & Biffen, Myrtaceae; AM) and lemon myrtle (Backhousia citriodora F. Muell, Myrtaceae; LM) as well as a reference sample bay leaf (Laurus nobilis L., Lauraceae; BL) were examined for potential cytoprotective properties. All native herbs exhibited greater cellular antioxidant activity as measured by the cellular antioxidant activity (CAA) assay than bay leaf and reduced the hydrogen peroxide (H(2)O(2)) induced death of hepatocellular carcinoma (HepG2) cells by 25-50%. All herb extracts reduced the proliferation of colon (HT-29; IC(50)=0.75-1.39mg/ml), stomach (AGS; IC(50)=0.59-1.88mg/ml), bladder (BL13; IC(50)=0.56-1.12mg/ml) and liver (HepG2; IC(50)=0.38-1.36mg/ml) cancer cells. No significant reduction of cell viability of non-transformed colon (CCD-18Co; IC(50)>2.0mg/ml) and mixed stomach and intestine (Hs 738.St/Int; IC(50)>2.0mg/ml) cells was observed. Flow cytometry analysis and the results of the cytokinesis block micronucleus cytome (CBMNCyt) assay conducted with respectively, promyelocytic leukaemia (HL-60) and colon adenocarcinoma (HT-29) cells suggest an increase in apoptosis following treatment with the herb extracts. The occurrence of apoptotic cells coincided with an increase in caspase-3 enzyme activity. The results of the CBMNCyt assay suggested no direct DNA damage in colon adenocarcinoma (HT-29) cells as a result of treatment with all extracts, applied at final concentrations of 0.5 and 1.0mg/ml.

Can cytogenetics explain the possible association between exposure to extreme low-frequency magnetic fields and Alzheimer's disease?

Recently, a number of epidemiological studies have suggested that occupational as well as residential exposure to extreme low-frequency electromagnetic fields (ELF-EMFs) may be a risk factor for Alzheimer's disease. This is not proven yet and there are no known biological mechanisms to explain this alleged association. Alzheimer's disease is characterized by a number of events that have, at least partially, a genetic origin. In particular, trisomy of chromosomes 17 and 21 seems to be involved. Overall ELF-EMFs have not been identified as genotoxic agents, but there are some papers in the scientific literature that indicate that they may enhance the effects of agents that are known to induce mutations or tumors. There are also some indications that ELF-EMFs may induce aneuploïdy. This opens some perspectives for investigating the alleged association between ELF-EMFs and Alzheimer's. This paper reviews the possibility of a cytogenetic association between the electromagnetic fields and Alzheimer's disease.

Germinal and Somatic Trisomy 21 Mosaicism: How Common is it, What are the Implications for Individual Carriers and How Does it Come About?

It is well known that varying degrees of mosaicism for Trisomy 21, primarily a combination of normal and Trisomy 21 cells within individual tissues, may exist in the human population. This involves both Trisomy 21 mosaicism occurring in the germ line and Trisomy 21 mosaicism documented in different somatic tissues, or indeed a combination of both in the same subjects. Information on the incidence of Trisomy 21 mosaicism in different tissue samples from people with clinical features of Down syndrome as well as in the general population is, however, still limited. One of the main reasons for this lack of detailed knowledge is the technological problem of its identification, where in particular low grade/cryptic Trisomy 21 mosaicism, i.e. occurring in less than 3-5% of the respective tissues, can only be ascertained by fluorescence in situ hybridization (FISH) methods on large cell populations from the different tissue samples.In this review we summarize current knowledge in this field with special reference to the question on the likely incidence of germinal and somatic Trisomy 21 mosaicism in the general population and its mechanisms of origin. We also highlight the reproductive and clinical implications of this type of aneuploidy mosaicism for individual carriers. We conclude that the risk of begetting a child with Trisomy 21 Down syndrome most likely is related to the incidence of Trisomy 21 cells in the germ line of any carrier parent. The clinical implications for individual carriers may likewise be dependent on the incidence of Trisomy 21 in the relevant somatic tissues. Remarkably, for example, there are indications that Trisomy 21 mosaicism will predispose carriers to conditions such as childhood leukemia and Alzheimer's Disease but there is on the other hand a possibility that the risk of solid cancers may be substantially reduced.

Chromosomal aneuploidy in the aging brain

Mechanisms that govern genome integrity and stability are major guarantors of viability and longevity. As people age, memory and the ability to carry out tasks often decline and their risk for neurodegenerative diseases increases. The biological mechanisms underlying this age-related neuronal decline are not well understood. Genome instability has been implicated in neurodegenerative processes in aging and disease. Aneuploidy, a chromosome content that deviates from a diploid genome, is a recognized form of genomic instability. Here, we will review chromosomal aneuploidy in the aging brain, its possible causes, its consequences for cellular homeostasis and its possible link to functional decline and neuropathies.

Association of micronucleus frequency with neurodegenerative diseases

Micronuclei (MNi) can originate either from chromosome breakage or chromosome malsegregation events and are therefore ideal biomarkers to investigate genomic instability. Studies in peripheral lymphocytes of patients with neurodegenerative diseases, mainly Alzheimer's disease (AD) and Parkinson's disease (PD), revealed an increased micronucleus (MN) frequency in both disorders but originating mainly from chromosome malsegregation events in AD and from chromosome breakage events in PD. Studies in other neurodegenerative diseases are largely missing, and some data in premature ageing disorders characterised by neurodegeneration and/or neurological complications, such as Ataxia telangiectasia, Werner's syndrome, Down's syndrome (DS) and Cockayne's syndrome, indicate that MNi increase with ageing in cultured cells. An increased frequency of aneuploidy characterises several tissues of AD patients, as well as of individuals at increased risk to develop AD, such as mothers of DS individuals and DS subjects themselves. The use of the buccal MN cytome assay in AD and DS subjects allowed finding significant changes in the MN frequency as well as other cellular modifications reflecting reduced regenerative capacity compared to age- and gender-matched controls. These changes in buccal cytome ratios may prove useful as potential future diagnostics to identify individuals of increased risk for these disorders.

Micronucleus formation detected by live-cell imaging

Although micronuclei (MNi) have been extensively used to evaluate genotoxic effects and chromosome instability, the most basic issue regarding their formation was not completely addressed until recently, due to limitations of traditional experimental methods. The development of live-cell imaging, combined with genetically engineered chromosome labelling techniques makes it possible to investigate the origin of a micronucleus in a single cell in a real-time and high-throughput manner. Here, we review all the available studies on the origins of MNi in live cells and discuss novel findings based on this recently emerged methodology. Some unsolved questions on MNi formation and limitations of live-cell imaging in the investigation of MNi have also been discussed.

Sorted cell microarrays as platforms for high-content informational bioassays

We report on surface-engineered microarrays that provide in situ cell sorting, localization, and immobilization of various subsets of human primary lymphocytes, followed by an on-chip bioassay for ionizing-radiation-induced cytogenetic damage. The microarray format eliminates the necessity of separating cell sub-populations by alternative means (such as fluorescence- or magnetic-activated cell sorting) prior to performing informational bioassays. To exemplify the potential of this on-chip cytometry approach, we have integrated the cytokinesis-block micronucleus cytome (CBMNcyt) assay with the microarray platform for analysis of the chromosome damage profile of specific subsets of human peripheral lymphocytes. Microarray results were compared with data obtained from the traditional CBMNcyt assay on heterogeneous lymphocyte populations, and with flow cytometry data. Our results suggest that cytogenetic damage caused by ionizing radiation is not uniformly distributed across all lymphocytes subsets, but rather concentrated in specific subsets. The salient features of our approach are that it requires very small volumes of reagents, allows sorting of lymphocyte subsets in situ, increases parallelism of cell assays and is amenable to high content microscopy analysis. The on-chip cytometry format opens new vistas for advanced cell-based assays, potentially bringing to light important information which remains hidden with conventional assays and hence engendering new discoveries in cell biology.

The role of the dopamine transporter in dopamine-induced DNA damage

The neurotransmitter dopamine causes DNA damage, oxidative stress and is involved in the pathology of neurological diseases. To elucidate this potential link we investigated the mechanism of dopamine-induced DNA damage. We studied the role of the dopamine transporter (DAT) in MDCK and MDCK-DAT cells, containing the human DAT gene. After treatment with dopamine, only MDCK-DAT cells showed elevated chromosomal damage and dopamine uptake. Although stimulation of dopamine type 2 receptor (D(2)R) with quinpirole in the absence of dopamine did not induce genotoxicity in rat neuronal PC12 cells, interference with D(2)R signaling by inhibition of G-proteins, phosphoinositide 3 kinase and extracellular signal-regulated kinases reduced dopamine-induced genotoxicity and affected the ability of DAT to take up dopamine. Furthermore, the D(2)R antagonist sulpiride inhibited the dopamine-induced migration of DAT from cytosol to cell membrane. To determine whether oxidation of dopamine by monoamine oxidase (MAO) is relevant in its genotoxicity, we inhibited MAO, which reduced the formation of micronuclei and of the oxidative DNA adduct 8-oxodG. Overall, dopamine exerted its genotoxicity in vitro upon transport into the cells and oxidation by MAO. D(2)R signaling was involved in the genotoxicity of dopamine by affecting activation and cell surface expression of DAT and hence modulating dopamine uptake.

Folate and methionine metabolism in autism: a systematic review

BACKGROUND

Autism is a complex neurodevelopmental disorder that is increasingly being recognized as a public health issue. Recent evidence has emerged that children with autism may have altered folate or methionine metabolism, which suggests the folate-methionine cycle may play a key role in the etiology of autism.

OBJECTIVE

The objective was to conduct a systematic review to examine the evidence for the involvement of alterations in folate-methionine metabolism in the etiology of autism.

DESIGN

A systematic literature review was conducted of studies reporting data for metabolites, interventions, or genes of the folate-methionine pathway in autism. Eighteen studies met the inclusion criteria, 17 of which provided data on metabolites, 5 on interventions, and 6 on genes and their related polymorphisms.

RESULTS

The findings of the review were conflicting. The variance in results can be attributed to heterogeneity between subjects with autism, sampling issues, and the wide range of analytic techniques used. Most genetic studies were inadequately powered to provide more than an indication of likely genetic relations.

CONCLUSIONS

The review concluded that further research is required with appropriately standardized and adequately powered study designs before any definitive conclusions can be made about the role for a dysfunctional folate-methionine pathway in the etiology of autism. There is also a need to determine whether functional benefits occur when correcting apparent deficits in folate-methionine metabolism in children with autism.

Dietary reference values of individual micronutrients and nutriomes for genome damage prevention: current status and a road map to the future

Damage to the genome is recognized as a fundamental cause of developmental and degenerative diseases. Several micronutrients play an important role in protecting against DNA damage events generated through endogenous and exogenous factors by acting as cofactors or substrates for enzymes that detoxify genotoxins as well as enzymes involved in DNA repair, methylation, and synthesis. In addition, it is evident that either micronutrient deficiency or micronutrient excess can modify genome stability and that these effects may also depend on nutrient-nutrient and nutrient-gene interaction, which is affected by genotype. These observations have led to the emerging science of genome health nutrigenomics, which is based on the principle that DNA damage is a fundamental cause of disease that can be diagnosed and nutritionally prevented on an individual, genetic subgroup, or population basis. In this article, the following topics are discussed: 1) biomarkers used to study genome damage in humans and their validation, 2) evidence for the association of genome damage with developmental and degenerative disease, 3) current knowledge of micronutrients required for the maintenance of genome stability in humans, 4) the effect of nutrient-nutrient and nutrient-genotype interaction on DNA damage, and 5) strategies to determine dietary reference values of single micronutrients and micronutrient combinations (nutriomes) on the basis of DNA damage prevention. This article also identifies important knowledge gaps and future research directions required to shed light on these issues. The ultimate goal is to match the nutriome to the genome to optimize genome maintenance and to prevent pathologic amounts of DNA damage.

Dopamine induces supernumerary centrosomes and subsequent cell death through Cdk2 up-regulation in dopaminergic neuronal cells

Aggregation of proteins in the centrosome is implicated in the pathophysiology of Parkinson's disease. However, the relevance of the centrosome in neurodegeneration is still obscure. Centrosome duplication is initiated by the cyclin E/cyclin-dependent kinase 2 (Cdk2) complex. The present study determined changes in cyclin E or Cdk2 expression and in the centrosomal structure in dopaminergic neuronal CATH.a cells exposed to 50, 100 and 150 micromolar dopamine (DA) for 24 h. DA induced significant increase in Cdk2 protein and cyclin E protein, but not cyclin e mRNA. In DA-treated cells, the intense cyclin E- and Cdk2-immunofluorescence signals were co-localized around large and supernumerary centrosomes, and these two parameters of centrosome amplification were significantly increased compared with the control. Simultaneous co-treatment with DA and a Cdk2 inhibitor blocked centrosome amplification and enhanced cell viability. Our results demonstrated that DA could lead to cyclin E accumulation and Cdk2 up-regulation triggering supernumerary centrosomes and apoptotic cell death.

Comparative genome hybridization array analysis for sporadic Parkinson's disease

Parkinson disease (PD) is a common neurodegenerative disorder, characterized by the loss of midbrain dopamine neurons and Lewy body inclusions. We investigated array CGH to analyze gain or loss of genetic material from 30 patients with PD. We identified the frequent copy number variations in PD; gains in 1p21.1, 4p15.31, 5p15.33, 6q24.1, 7q35, 8q24.3, 10q26.3, 11p15.5-15.4, 12q21.2, 16p13.3, 18q12.3 and 22q13.31, and losses in 1p36.33, and 5q13.2. These findings enable a better description of genetic variations in PD, and could provide a foundation for understanding the critical regions of the genome that may be involved in the development of PD.

Central and peripheral dopamine transporter reduction in Parkinson's disease

OBJECTIVE

Previous reports showed the reduction of dopamine transporter immunoreactivity in peripheral blood lymphocytes in Parkinson's disease. In this work, we sought to investigate the possible correlation between central and peripheral dopamine transporter immunoreactivity values in a group of 11 drug-naive patients with Parkinson's disease.

METHODS

Densitometric measurements of dopamine transporter immunoreactivity in peripheral blood lymphocytes was accomplished as described recently, using a monoclonal antidopamine transporter antibody. Dopamine transporter binding in the caudate and putamen nuclei was measured by means of (123)I-fluopane single-photon emission computed tomography in the same patients.

RESULTS

The results failed to show any significant correlation between dopamine transporter immunoreactivity in peripheral blood lymphocytes and the caudate or putamen dopamine transporter binding. Moreover, dopamine transporter immunoreactivity in peripheral blood lymphocytes was reduced also in the single patient with normal striatal dopamine transporter binding.

DISCUSSION

These results indicate the lack of correlation between central and peripheral dopamine transporter reduction in Parkinson's disease, using the methodologies applied herein. They therefore suggest that the two phenomena are unlikely to share a common pathogenetic mechanism.

Grape seed polyphenols and curcumin reduce genomic instability events in a transgenic mouse model for Alzheimer's disease

The study set out to determine (a) whether DNA damage is elevated in mice that carry mutations in the amyloid precursor protein (APP695swe) and presenilin 1 (PSEN1-dE9) that predispose to Alzheimer's disease (AD) relative to non-transgenic control mice, and (b) whether increasing the intake of dietary polyphenols from curcumin or grape seed extract could reduce genomic instability events in a transgenic mouse model for AD. DNA damage was measured using the micronucleus (MN) assay in both buccal mucosa and erythrocytes and an absolute telomere length assay for both buccal mucosa and olfactory bulb tissue. MN frequency tended to be higher in AD mice in both buccal mucosa (1.7-fold) and polychromatic erythrocytes (1.3-fold) relative to controls. Telomere length was significantly reduced by 91% (p=0.04) and non-significantly reduced by 50% in buccal mucosa and olfactory bulbs respectively in AD mice relative to controls. A significant 10-fold decrease in buccal MN frequency (p=0.01) was found for AD mice fed diets containing curcumin (CUR) or micro-encapsulated grape seed extract (MGSE) and a 7-fold decrease (p=0.02) for AD mice fed unencapsulated grape seed extract (GSE) compared to the AD group on control diet. Similarly, in polychromatic erythrocytes a significant reduction in MN frequency was found for the MGSE cohort (65.3%) (p<0.05), whereas the AD CUR and AD GSE groups were non-significantly reduced by 39.2 and 34.8% respectively compared to the AD Control. A non-significant 2-fold increase in buccal cell telomere length was evident for the CUR, GSE and MGSE groups compared to the AD control group. Olfactory bulb telomere length was found to be non-significantly 2-fold longer in mice fed on the CUR diet compared to controls. These results suggest potential protective effects of polyphenols against genomic instability events in different somatic tissues of a transgenic mouse model for AD.