Effect of vitamin E on chromosomal aberrations in lymphocytes from patients with Down's syndrome

Neurologic complications of Down syndrome: a systematic review

Down syndrome (DS) is one of the most well-recognized genetic disorders. Persons with DS are known to have a variety of co-morbid medical problems, affecting nearly all organ systems. Improved healthcare interventions and research have allowed for increased life span of persons with DS, although disorders of the neurologic system remain underexplored. The purpose of this systematic review is to provide clinically pertinent information on the neurological phenotypes of frequently occurring or clinically relevant conditions. A retrospective review of MEDLINE, Scopus, and Pubmed were used to identify sources among seventeen, clinically relevant, search categories. MeSH terms all contained the phrase "Down Syndrome" in conjunction with the topic of interest. 'Frequently-occurring' was defined as prevalent in more than 10% of persons with DS across their lifespan, whereas 'clinically-relevant' was defined as a disease condition where early diagnosis or intervention can augment the disease course. In total, 4896 sources were identified with 159 sources meeting criteria for inclusion. Seventeen clinical conditions were grouped under the following subjects: hypotonia, intellectual and learning disability, cervical instability, autism spectrum disorder, epilepsy, cerebrovascular disease, Alzheimer's disease and neuropsychiatric disease. The results of this review provide a blueprint for the clinical neurologist taking care of persons with DS across the age spectrum and indicate that there are many underrecognized and misdiagnosed co-occurring conditions in DS, highlighting the need for further research.

The Vitamin E Analog Gamma-Tocotrienol (GT3) Suppresses Radiation-Induced Cytogenetic Damage

Purpose

Ionizing radiation (IR) generates reactive oxygen species (ROS), which cause DNA double-strand breaks (DSBs) that are responsible for cytogenetic alterations. Because antioxidants are potent ROS scavengers, we determined whether the vitamin E isoform γ-tocotrienol (GT3), a radio-protective multifunctional dietary antioxidant, can suppress IR-induced cytogenetic damage.

Methods

We measured DSB formation in irradiated primary human umbilical vein endothelial cells (HUVECs) by quantifying the formation of γ-H2AX foci. Chromosomal aberrations (CAs) were analyzed in irradiated HUVECs and in the bone marrow cells of irradiated mice by conventional and fluorescence-based chromosome painting techniques. Gene expression was measured in HUVECs with quantitative reverse transcriptase polymerase chain reaction (qRT-PCR).

Results

GT3 pretreatment reduced DSB formation in HUVECS, and also decreased CAs in HUVECs and mouse bone marrow cells after irradiation. Moreover, GT3 increased expression of the DNA-repair gene RAD50 and attenuated radiation-induced RAD50 suppression.

Conclusions

GT3 attenuates radiation-induced cytogenetic damage, possibly by affecting RAD50 expression. GT3 should be explored as a therapeutic to reduce the risk of developing genetic diseases after radiation exposure.

Antioxidative and antigenotoxic effect of vitamin E against patulin cytotoxicity and genotoxicity in HepG2 cells

Patulin (PAT) is a mycotoxin produced in fruits, mainly in apples, by certain species of Penicillium, Aspergillus, and Byssochlamys. It has been shown that PAT is cytotoxic, genotoxic, and mutagenic in different cell types. Several studies incriminate the oxidative stress as a mechanism of PAT-mediated toxicity. In this context, our aim was to investigate the protective role of Vitamin E (Vit E), an antioxidant agent, against PAT induced cytotoxicity and genotoxicity in cultured HepG2 cells. The obtained results showed that addition of Vit E in cells treated with PAT significantly reduce cell mortality induced by this toxin. In the same conditions, Vit E decreased the intracellular level of ROS, reduced PAT induced p53 expression, and reversed PAT induced DNA damage. In addition, Vit E prevented significantly the percentage of chromosome aberrations induced by PAT in HepG2 cells in a concentration dependant manner. These results suggest that Vit E, an exogenous antioxidant agent, plays an important role in defense against PAT-induced cytotoxicity and genotoxicity, which confirms the involvement of oxidative stress in the induction of DNA damage by PAT in HepG2 cells.

Levels of non enzymatic antioxidants in Down syndrome

OBJECTIVES

To confirm the clinical diagnosis of Down syndrome by chromosomal analysis and to explore the oxidative stress in children with Down syndrome by estimating the levels of non enzymatic antioxidants like reduced glutathione(GSH) and total antioxidants status (TAS).

METHODS

The study included 31 clinically diagnosed children with Down syndrome with equal number of age and sex matched controls. Trisomy 21 was confirmed by conventional lymphocyte cell culture. Erythrocytic reduced glutathione (GSH) and plasma total antioxidant status (TAS) were measured sphectrophotometrically.

RESULTS

The levels of erythrocytic reduced glutathione (GSH) and plasma total antioxidant status (TAS) were significantly reduced in children with Down syndrome.

CONCLUSIONS

Children with Down syndrome have elevated levels of oxidative stress . Hence antioxidant therapy can be beneficial among them.

Dl-α-tocopherol enhances the herbicide 1,1'-dimetyl-4,4'-bipyridium dichloride (paraquat, PQ) genotoxicity in cultured anuran leukocytes

This cytogenetic and pharmacological study attempts to clarify genotoxicity-enhancement-effect of dl-α-tocopherol (one form of vitamin E) in combination with the herbicide 1,1'-dimetyl-4,4'-bipyridium dichloride (paraquat, PQ) on cultured anuran leukocytes using the superoxide dismutase-mimic Mn(III)tetrakis(1-methyl-4-pyridyl)porphyrin (Mn(III)TMpyP), the hydrogen peroxide-scavenger catalase and the electron donor nicotinamide adenine dinucleotido phosphate (NADPH). PQ only was found to induce structural chromosomal damage in cultured anuran leukocytes in a dose-dependent manner. PQ plus NADPH, which served as positive control, enhanced the genotoxic effect of PQ. Dl-α-tocopherol only did not induce any structural chromosomal damage in the leukocytes. PQ plus dl-α-tocopherol, however, enhanced the genotoxic effect of PQ. PQ plus Mn(III)TMpyP, PQ plus catalase and PQ plus Mn(III)TMpyP plus catalse suppressed the genotoxic effect of PQ. Furthermore, PQ plus dl-α-tocopherol-enhanced chromosomal damage was also inhibited by Mn(III)TMpyP plus catalase. These results suggest that dl-α-tocopherol in combination with PQ functions as an electron donor to PQ.

Prolonged coenzyme Q10 treatment in Down syndrome patients: effect on DNA oxidation

Oxidative stress is known to play a relevant role in Down syndrome (DS) and its effects are documented from embryonic life. Oxidative DNA damage has been shown to be significantly elevated in Down syndrome patients, and this has been indicated as an early event promoting neurodegeneration and Alzheimer type dementia. The aim of this study was to investigate the efficacy of coenzyme Q(10) (CoQ(10)) in delaying the effect of oxidative damage in these patients. In our previous study we demonstrated a mild protective effect of CoQ(10) on DNA, although the treatment was unable to modify the overall extent of oxidative damage at the patient level. Possible limitations of the previous study were: time of treatment (6 months) or spectrum of DNA lesions detected. In order to overcome these limitations we planned a continuation of the trial aimed at evaluating the effects of CoQ(10) following a prolonged treatment. Our results highlight an age-specific reduction in the percentage of cells showing the highest amount of oxidized bases, indicating a potential role of CoQ(10) in modulating DNA repair mechanisms.

Aerobic exercise reduced oxidative stress in saliva of persons with Down syndrome

The aim of this investigation was to examine the effect of aerobic exercise (AE) on uric acid (UA), total antioxidant activity (TAA), oxidative stress (OS) and nitrite a stable nitric oxide (NO) metabolite in saliva from persons with Down syndrome (DS). Stimulated saliva was sampled from 12 participants 1 hour before and immediately after a 1,600-meter walking test. Uric acid (UA) was assayed by enzymatic method, TAA by ABTS method, lipid hydroperoxides (OS marker) by the ferrous iron/xylenol orange (FOX) method and nitrite concentration by the Griess reaction. Aerobic exercise (AE) caused a decrease in salivary lipid hydroperoxides in persons with DS (p = 0.001). Aerobic exercise (AE), however, did not affect salivary UA, TAA, and nitrite. This result suggested that AE can be considered as a way to reduce the OS in persons with DS, particularly in the mouth cavity.

Oxidative and genotoxic damage after radio‐iodine therapy of Graves' hyperthyroidism

PURPOSE

To evaluate genetic damage and oxidative stress following a single therapeutic dose of 131I in Graves' disease patients monitored up to 180 days after treatment.

MATERIALS AND METHODS

Genetic damage induction was estimated as the increase in micronuclei in peripheral lymphocytes of patients. As indicators of radiogenic oxidative stress, vitamin E and lipoperoxide levels were assessed in the plasma of patients, as well as the release of plasmic clastogenic factors measured by the induction of micronuclei in vitro in peripheral lymphocytes of a healthy donor.

RESULTS

Vitamin E depletion lasted at least 3 days and the basal level was restored within 7 days. No statistically significant variations were observed in lipoperoxide plasma levels. A sharp increase of micronuclei in the peripheral lymphocytes of patients was correlated (p < 0.001) with the release of clastogenic factor in the plasma. The highest micronucleus value was negatively correlated (p < 0.03) with the lowest vitamin E level observed in each patient.

CONCLUSIONS

Micronuclei induction was the direct consequence not only of the energy deposition of 131I on the genetic material, but also of oxidative stress, likely via the release of clastogenic factor.

[Biochemical alterations in patients with Down syndrome]

Down syndrome is a chromosome abnormality with specific clinical symptoms and mental retardation caused by trisomy of chromosome 21. The basic genetic change cannot be cured, the control of the associated symptoms, however, may improve the patients' quality of life.

AIMS

Authors studied the possible correlations between the Down-specific genes and the related biochemical changes. Expression of superoxide dismutase, cystathionine-beta-synthase and S100 protein was investigated. Further aim of the study was to determine the total serum antioxidant capacity (transferrin, ferritin, total protein, albumin and bilirubin) along with the extracellular antioxidants as well as concentrations of homocysteine, folic acid, and vitamin B 12 . To assess the vascular damage, the activity of NAG and S100B level was measured.

METHODS

Standard laboratory methods were used to determine the antioxidant capacity (Stocks, 1974), homocysteine (HPLC), folic acid (capture, IMX-Abbott), vitamin B 12 (MEIA, IMX-Abbott), S100 B protein (chemiluminescence sandwich immunoassay) levels, and N-acetyl-beta-D-glucosaminidase (spectrophotometry).

RESULTS

Plasma homocysteine value proved to be lower in 7 of the 30 and higher in 6 of the 30 patients studied than the reference range. Plasma homocysteine was found 95 +/- 21% of the reference value. Relative value of plasma folic acid - expressed in percent of the normal value - was 85 +/- 51%, and that of B 12 was 78 +/- 30%. Deficiency of folic acid was detected in 2 of the 30, decreased level of B 12 in 2 of the 30 patients enrolled. No difference was found in antioxidant activity values between Down syndrome patients and healthy controls, however, neither of them reached the adult reference range. S100 protein concentration of 4-8 times higher values (average value: 0.68 +/- 0.27 microg/l) than upper limit of the reference range was observed (> 1 year: > 0.15 microg/l). Mean value of serum N-acetyl-beta-D-glucosaminidase remained within the reference range (10-30 U/l). No statistically significant correlation between the antioxidant activity and N-acetyl-beta-D-glucosaminidase values could be observed.

CONCLUSION

The lower homocysteine, folic acid and B 12 values may be considered as the consequence of an increased cystathionine-beta-synthase activity ("atheroma free model"). There was no significant alteration in antioxidant activity level. It can be supposed that the hydrogene peroxide produced due to increased expression of superoxide dismutase is metabolized by the induced glutathione-peroxidase and catalase keeping by this the balance of the antioxidant system. This hypothesis is supported by the normal N-acetyl-beta-D-glucosaminidase values not indicating any vascular damage. The high S100 values, however, reflect certain brain damage which shows a progress with the age. Based on these experiences, regular control of these parameters is recommended. Furthermore authors think that folic acid supplementation is indicated in order to improve the patients' learning capacity, inhibit the development of Alzheimer symptoms and improve the quality of life.

Oxidative stress: A bridge between Down's syndrome and Alzheimer's disease

Besides the genetic, biochemical and neuropathological analogies between Down's syndrome (DS) and Alzheimer's disease (AD), there is ample evidence of the involvement of oxidative stress (OS) in the pathogenesis of both disorders. The present paper reviews the publications on DS and AD in the past 10 years in light of the "gene dosage" and "two-hit" hypotheses, with regard to the alterations caused by OS in both the central nervous system and the periphery, and the main pipeline of antioxidant therapeutic strategies. OS occurs decades prior to the signature pathology and manifests as lipid, protein and DNA oxidation, and mitochondrial abnormalities. In clinical settings, the assessment of OS has traditionally been hampered by the use of assays that suffer from inherent problems related to specificity and/or sensitivity, which explains some of the conflicting results presented in this work. For DS, no scientifically proven diet or drug is yet available, and AD trials have not provided a satisfactory approach for the prevention of and therapy against OS, although most of them still need evidence-based confirmation. In the future, a balanced up-regulation of endogenous antioxidants, together with multiple exogenous antioxidant supplementation, may be expected to be one of the most promising treatment methods.

Complementary and alternative therapies for Down syndrome

In their role as committed advocates, parents of children with Down syndrome have always sought alternative therapies, mainly to enhance cognitive function but also to improve their appearance. Nutritional supplements have been the most frequent type of complementary and alternative therapy used. Cell therapy, plastic surgery, hormonal therapy, and a host of other therapies such as massage therapy have been used. There is a lack of well-designed scientific studies on the use of alternative therapies in individuals with Down syndrome. Antioxidants hold theoretical promise for treatment of the cognitive, immune, malignancy, and premature aging problems associated with Down syndrome. Medications for treatment of Alzheimer's disease may also result in benefit for the population of individuals with Down syndrome.

Anti-oxidant gene expression imbalance, aging and Down syndrome

The expression of copper zinc superoxide dismutase (SOD1), manganese superoxide dismutase (SOD2), glutathione peroxidase (GPx), and catalase (CAT) genes have been detected in human skin fibroblast cells for 2 year normal child (control), 50 year old normal male and female and a 1 year old Down Syndrome (DS) male and female with established trisomy karyotype using the RT-PCR technique. Differential expression of these genes is quantified individually against a beta-Actin gene that has been employed as an internal control. The immunoblotting of cell lysate proteins with polyclonal antibodies exhibit SOD1 (16 kD), SOD2 (40 kD), GPx (23 and 92 kD), CAT (64 kD), and Actin (43 kD) as translational products. The results demonstrate that the enhancement in the level of mRNAs encoding SOD1 in DS male and female, as well as aged male and female are 51, 21, 31 and 50% respectively compared to the normal child (control). In SOD2, DS male and female display higher (176%) and lower (26%) levels of expression whereas aged male and female exhibit enhanced levels of expression (66 and 119%) respectively compared to the control. This study demonstrates that DS affects the female less than the male whereas in the aging process, the female is more prone to oxidative damage than the male. These results not only indicate that the level of GPx mRNA is constant except in DS male, which shows a downward regulation but that even CAT mRNA is upward regulated in aged as well as in DS males and females. These disproportionate changes in anti-oxidant genes, which are incapable of coping with over expressed genes, may contribute towards the aging process, dementia and Down syndrome.

The protective effect and mechanism of soybean oil and its extracts on DNA damage in human ECV304 cells exposed to UV-C

The degree of DNA damage in the human endothelial cell line ECV304 exposed to UV-C, with or without the presence of soybean oil (SBO), was assessed by the Comet assay. After 5-min exposure to UV-C, the %Tail DNA in the ECV304 cells ranged from 0% to 20% for SBO treatment groups and from 50% to 70% for the control group. The result indicated a strong protective effect of SBO against UV-C-induced DNA damage. To clarity the mechanism of this protective effect of SBO, the methanol extract of SBO (MESO) was analyzed and its capacity against UV-C-induced DNA damage was evaluated. Gas chromatography mass spectrometry (GC-MS) analysis confirmed that MESO contained many antioxidants including n-3-polyunsaturated fatty acid (n-3-PUFA), tocopherols and phytosterols. Comet assay revealed that the MESO was also active in reducing the DNA damage dose-dependently (P<0.0001) vs. control in the ECV304 cells. Therefore, we concluded that these potential antioxidants may be responsible for the scavenge of oxidative radicals induced by UV-C irradiation. This study suggested that dietary SBO, which is abundant of antioxidants, may reduce the content or impact of reactive oxygen species (ROS) and lower the risk of diseases caused by ROS.

In vitro study on the genotoxicity of dichloromethane extracts of valerian (DEV) in human endothelial ECV304 cells and the effect of vitamins E and C in attenuating the DEV-induced DNA damages

To study the genotoxicity of valepotriates in vitro, the degree of DNA damage in human endothelial cell line ECV304 treated with 5-60 microg/mL of dichloromethane extracts of valerian (DEV) was analyzed by the Comet assay. No DNA damage was observed in ECV304 cells after culture for 48 h in the presence of 5,10, and 20 microg/mL of DEV. But a moderate degree of DNA damage was observed in the cells treated with 40 or 60 microg/mL of DEV. Quantitative analyses of DNA damage in the presence of antioxidants vitamin E (VE) and vitamin C (VC) were also carried out. The study revealed that both VE and VC exhibited a biphasic effect, reducing DEV-induced DNA damages at low concentrations but increasing them at high concentrations. We concluded that (1). the observed DNA damage in ECV304 cells induced by high concentrations of DEV was mainly through epigenetic mechanisms, i.e., reactive oxygen species mediated oxidative DNA damage (2). at the low doses, DEV did not appear to have any significant genotoxicity in ECV304 cells, and (3). VE and VC, at proper concentrations, can reduce or eliminate the adverse effects derived from high doses of DEV. This study should serve as scientific guidance for clinical therapy of valerian preparation.

Down syndrome and Alzheimer's disease: a link between development and aging

A subset of aged individuals with Down syndrome (DS) exhibits the clinical features of Alzheimer's disease (AD) but our ability to detect dementia in this population is hampered by developmental differences as well as the sensitivity of existing test tools. Despite the apparent clinical heterogeneity in aged individuals with DS, age-associated neuropathology is a consistent feature. This is due to the fact that trisomy 21 leads to a dose-dependent increase in the production of the amyloid precursor protein and subsequently the production of the amyloidogenic fragments leading to early and predominant senile plaque formation. A review of the existing literature indicates that oxidative damage and neuroinflammation may interact to accelerate the disease process particularly in individuals with DS over the age of 40 years. By combining clinical information with measures of brain-region specific neuropathology we can "work backwards" and identify the earliest and most sensitive clinical change that may signal the onset of AD. For the past 50 years, investigators in the fields of mental retardation, developmental disabilities, and aging have been interested in the curious link between AD and DS. The morphologic and biochemical origins of AD are seen in the early years of the lifespan for individuals with DS. Study of the process by which AD evolves in DS affords an opportunity to understand an important link between development and aging. This review will focus on advances in the molecular and clinical basis of this association.

Vitamin E and genome stability

Free radicals and reactive oxygen species (ROS) which are generated continuously cause mutagenic alterations resulting in cancer, aging and abnormalities in the nervous system. Accumulating evidence indicates that Vitamin E, the most potent lipid peroxyl radical scavenger, may reduce free radical induced chromosomal damages through inhibition of free radical formation, and activation of endonuclease that can be triggered by intracellular oxidative stress, and by increasing the rate of removal of damaged DNA. Although some studies suggest a potential usefulness of Vitamin E in the prevention of mutagenic effects caused by genotoxic free radicals, other studies report no effects. Thus the data are not conclusive enough to be used as a basis to change the current recommended dietary allowances (RDA). Future research should address molecular mechanisms underlying the protective effects of Vitamin E and develop appropriate biologically relevant biomarkers of DNA damage to further help in determining the dietary levels of Vitamin E needed to protect the genetic pool from internally and externally induced DNA damages.

Fanconi anemia lymphocytes: effect of DL-alpha-tocopherol (Vitamin E) on chromatid breaks and on G2 repair efficiency

The high frequency of chromosomal breaks in Fanconi anemia (FA) lymphocytes has been related to the increased oxidative damage shown by these cells. The effect of 100 microM DL-alpha-tocopherol (Vitamin E) on the level of chromosomal damage in mitosis was studied in lymphocytes from five FA patients and from age matched controls, both under basal conditions and when G2 repair was prevented by 2.5 mM caffeine (G2 unrepaired damage). In addition, the effect of this antioxidant on G2 duration and the efficiency of G2 repair was also evaluated in the sample. alpha-Tocopherol (AT) decreased the frequency of chromosomal damage (under basal and inhibited G2 repair conditions) and the duration of G2 in FA cells. This antioxidant protective effect, expressed as the decrease in chromatid breaks, was greater in FA cells (50.8%) than in controls (25%). The efficiency of the G2 repair process (G2 R rate) defined as the ratio between the percentage of chromatid breaks repaired in G2 and the duration of this cell cycle phase was lesser in FA cells (10.6) than in controls (22.6). AT treatment slightly increased this G2 R rate, both in FA cells and controls. These results suggest that an increased oxidative damage and a lower G2 repair rate may be simultaneously involved in the high frequency of chromatid damage detected in FA cells.