Effect of antioxidant supplementation on pig and horse gamete storage

According to recent studies, antioxidant supplementation on gamete processing and/or storage solutions improvesgamete quality parameters, after cooling or storage at sub zero temperature. The aim of the present study was to investigate the effects of antioxidant supplementation on pig and horse gamete storage. The first study aimed to determine the effects of resveratrol (RESV) on the apoptotic status of porcine oocytes vitrified by Cryotop method, evaluating phosphatidylserine (PS) exteriorization and caspases activation. RESV(2µM) was added during: IVM (A); 2 h post-warming incubation (B); vitrification/warming and 2 h post-warming incubation (C); all previous phases (D). The obtained data demonstrate that RESV supplementation in the various steps of IVM and vitrification/warming procedure can modulate the apoptotic process, improving the resistance of porcine oocytes to cryopreservation-induced damage. In the second work different concentrations of RESV (10, 20, 40, and 80µM) were added during liquid storage of stallion sperm for 24 hours at either 10°C or 4°C, under anaerobic conditions. Our findings demonstrate that RESV supplementation does not enhance sperm quality of stallion semen after 24 hours of storage. Moreover, the highest RESV concentrations tested (40 and 80µM) could damage sperm functional status, probably acting as pro-oxidant. Finally, in the third work other two antioxidants, ascorbic acid (AA) (100 µM) and glutathione (GSH) (5mM) were added on boar freezing and/or thawing solutions. In our study different sperm parameters were evaluated before freezing and at 30 and 240 minutes after thawing. Our results showed that GSH and AA significantly improved boar sperm cryotolerance, especially when supplemented together to both freezing and thawing media. This improvement was observed in sperm viability and acrosome integrity, sperm motility, and nucleoprotein structure. Although ROS levels were not much increased by freeze-thawing procedures, the addition of GSH and AA to both freezing and thawing extenders significantly decreased intracellular peroxide levels.

New and More Sustainable Processes for the Synthesis of Phenolics: 2-phenoxyethanol and hydroxytyrosol

The research work has dealt with the study of new catalytic processes for the synthesis of fine chemicals belonging to the class of phenolics, namely 2-phenoxyethanol and hydroxytyrosol. The two synthetic procedures investigated have the advantages of being much closer to the Green Chemistry principles than those currently used industrially. In both cases, the challenge was that of finding catalysts and methods which led to the production of less waste, and used less hazardous chemicals, safer solvents, and reusable heterogeneous catalysts. In the case of 2-phenoxyethanol, the process investigated involves the use of ethylene carbonate (EC) as the reactant for phenol O-hydroxyethylation, in place of ethylene oxide. Besides being a safer reactant, the major advantage of using EC in the new synthesis is the better selectivity to the desired product achieved. Moreover, the solid catalyst based on Na-mordenite was fully recyclable. The reaction mechanism and the effect of the Si/Al ratio in the mordenite were investigated. In the case of hydroxytyrosol, which is one of the most powerful natural antioxidants, a new synthetic procedure was investigated; in fact, the method currently employed, the hydrolysis of oleuropein, an ester extracted from the waste water processing of the olive, makes use of large amounts of organic solvents (hexane, ethyl acetate), and involves several expensive steps of purification. The synthesis procedure set up involves first the reaction between catechol and 2,2-dimethoxyacetaldehyde, followed by the one-pot reduction of the intermediate to give the desired product. Both steps were optimized, in terms of catalyst used, and of reaction conditions, that allowed to reach ca 70% yield in each step. The reaction mechanism was investigated and elucidated. During a 3-month period spent at the University of Valencia (with Prof. A. Corma’s group), a process for the production of diesel additives (2,5-bis(propoxymethyl)furan) from fructose has been investigated.

Sperm of colourful males are better protected against oxidative stress

Sperm cells are highly vulnerable to free radicals, and sperm quality and male fertility are critically affected by oxidative stress. Recently, sexual ornaments, particularly carotenoid-based colourful traits, have been proposed to depend on a male's capacity to resist oxidative stress, and thus to signal sperm quality. We conducted an experimental test of this hypothesis on great tits Parus major, in which adults are sexually dichromatic in carotenoid-based breast plumage. We report the first evidence that ornaments and sperm quality may be linked through oxidative stress. When experimentally subjected to oxidative stress resulting from increased workload, less colourful males suffered a greater reduction in sperm motility and swimming ability, and increased levels of sperm lipid peroxidation compared to more colourful males. Moreover, the level of sperm lipid peroxidation was negatively correlated with sperm quality. Finally, carotenoid supplementation increased sperm quality of less colourful males, suggesting that pale males are deficient in carotenoid antioxidants.

Oxidative damage to DNA related to survivorship and carotenoid-based sexual ornamentation in the common yellowthroat

Carotenoid-based sexual ornaments are hypothesized to be reliable signals of male quality, based on an allocation trade-off between the use of carotenoids as pigments and their use in antioxidant defence against reactive oxygen species. Carotenoids appear to be poor antioxidants in vivo, however, and it is not clear whether variation in ornament expression is correlated with measures of oxidative stress (OXS) under natural conditions. We used single-cell gel electrophoresis to assay oxidative damage to erythrocyte DNA in the common yellowthroat (Geothlypis trichas), a sexually dichromatic warbler in which sexual selection favours components of the males’ yellow ‘bib’. We found that the level of DNA damage sustained by males predicted their overwinter survivorship and was reflected in the quality of their plumage. Males with brighter yellow bibs showed lower levels of DNA damage, both during the year the plumage was sampled (such that yellow brightness signalled current OXS) and during the previous year (such that yellow brightness signalled past OXS). We suggest that carotenoid-based ornaments can convey information about OXS to prospective mates and that further work exploring the proximate mechanism(s) linking OXS to coloration is warranted.

Antioxidant supplementation and endurance training: Win or loss?

Typically, free radicals are thought of as perpetrators of cell damage, ageing, even cancer, whereas antioxidants are seen as the defence against these threats. Accordingly, antioxidants are among the most common sports supplements used by amateur and professional athletes. However, the sensibility of this practice has recently been challenged in the scientific literature. This article briefly summarizes both positive and negative physiological effects of free radicals and antioxidants, culminating with emphasis on the signalling roles played by free radicals during training adaptations and the ability of superfluous antioxidants to weaken these desired signals, as revealed in several recent publications. The aim of this article is not to explicitly condemn antioxidant supplementation by athletes, but to underscore complexity of the situation and to champion efforts to achieve a deeper understanding of circumstances (e.g. dosage, timing, and setting) that might deem antioxidant supplementation as either largely beneficial or largely detrimental for endurance athletes in training.

Tight junctions in brain barriers during central nervous system inflammation

Homeostasis within the central nervous system (CNS) is a prerequisite to elicit proper neuronal function. The CNS is tightly sealed from the changeable milieu of the blood stream by the blood-brain barrier (BBB) and the blood-cerebrospinal fluid (CSF) barrier (BCSFB). Whereas the BBB is established by specialized endothelial cells of CNS microvessels, the BCSFB is formed by the epithelial cells of the choroid plexus. Both constitute physical barriers by a complex network of tight junctions (TJs) between adjacent cells. During many CNS inflammatory disorders, such as multiple sclerosis, human immunodeficiency virus infection, or Alzheimer's disease, production of pro-inflammatory cytokines, matrix metalloproteases, and reactive oxygen species are responsible for alterations of CNS barriers. Barrier dysfunction can contribute to neurological disorders in a passive way by vascular leakage of blood-borne molecules into the CNS and in an active way by guiding the migration of inflammatory cells into the CNS. Both ways may directly be linked to alterations in molecular composition, function, and dynamics of the TJ proteins. This review summarizes current knowledge on the cellular and molecular aspects of the functional and dysfunctional TJ complexes at the BBB and the BCSFB, with a particular emphasis on CNS inflammation and the role of reactive oxygen species.

Point mutation tRNA(Ser(UCN)) in a child with hearing loss and myoclonus epilepsy

We report on a family with a 12-year-old boy who suffered from a maternally inherited syndrome characterized by a combination of sensorineural hearing loss, myoclonus epilepsy, ataxia, severe psychomotor retardation, short stature, and diabetes mellitus. First, he showed a muscular hypotonia with hearing loss; later, he developed a myoclonus epilepsy, growth failure, and severe psychomotor retardation. At the age of 10 years, he developed diabetes mellitus. After initiation of combined ubiquinone and vitamin C treatment, we observed a progression in psychomotor development. Lactate and pyruvate levels in blood and cerebrospinal fluid were normal. No ragged red fibers or ultrastructural abnormalities were seen in a skeletal muscle biopsy. Biochemical assays of respiratory chain complex activities revealed decreased activity of complexes I and IV. By sequence analysis of mitochondrial DNA encoding transfer ribonucleic acids (RNAs), a homoplasmic T to C substitution at nucleotide position 7512 was found affecting a highly conserved base pair in the tRNA(ser(UCN)) acceptor stem. Asymptomatic family members of the maternal line were heteroplasmic for the mutation in blood samples. Analysis of mitochondrial DNA in patients with hearing loss and myoclonus epilepsy is recommended, even in the absence of laboratory findings. Therapeutically, ubiquinone and antioxidants can be beneficial.

Vitamin C deficiency in weanling guinea pigs: differential expression of oxidative stress and DNA repair in liver and brain

Neonates are particularly susceptible to malnutrition due to their limited reserves of micronutrients and their rapid growth. In the present study, we examined the effect of vitamin C deficiency on markers of oxidative stress in plasma, liver and brain of weanling guinea pigs. Vitamin C deficiency caused rapid and significant depletion of ascorbate (P < 0.001), tocopherols (P < 0.001) and glutathione (P < 0.001), and a decrease in superoxide dismutase activity (P = 0.005) in the liver, while protein oxidation was significantly increased (P = 0.011). No changes in lipid oxidation or oxidatively damaged DNA were observed in this tissue. In the brain, the pattern was markedly different. Of the measured antioxidants, only ascorbate was significantly depleted (P < 0.001), but in contrast to the liver, ascorbate oxidation (P = 0.034), lipid oxidation (P < 0.001), DNA oxidation (P = 0.13) and DNA incision repair (P = 0.014) were all increased, while protein oxidation decreased (P = 0.003). The results show that the selective preservation of brain ascorbate and induction of DNA repair in vitamin C-deficient weanling guinea pigs is not sufficient to prevent oxidative damage. Vitamin C deficiency may therefore be particularly adverse during the neonatal period.

Cerebral vasculature is the major target of oxidative protein alterations in bacterial meningitis

We have previously shown that antioxidants such as a-phenyl-tert-butyl nitrone or N-acetylcysteine attenuate cortical neuronal injury in infant rats with bacterial meningitis, suggesting that oxidative alterations play an important role in this disease. However, the precise mechanism(s) by which antioxidants inhibit this injury remain(s) unclear. We therefore studied the extent and location of protein oxidation in the brain using various biochemical and immunochemical methods. In cortical parenchyma, a trend for increased protein carbonyls was not evident until 21 hours after infection and the activity of glutamine synthetase (another index of protein oxidation) remained unchanged. Consistent with these results, there was no evidence for oxidative alterations in the cortex by various immunohistochemical methods even in cortical lesions. In contrast, there was a marked increase in carbonyls, 4-hydroxynonenal protein adducts and manganese superoxide dismutase in the cerebral vasculature. Elevated lipid peroxidation was also observed in cerebrospinal fluid and occasionally in the hippocampus. All of these oxidative alterations were inhibited by treatment of infected animals with N-acetylcysteine or alpha-phenyl-tert-butyl nitrone. Because N-acetylcysteine does not readily cross the blood-brain barrier and has no effect on the loss of endogenous brain antioxidants, its neuroprotective effect is likely based on extraparenchymal action such as inhibition of vascular oxidative alterations.

Oxidative stress in brain during experimental bacterial meningitis: differential effects of alpha-phenyl-tert-butyl nitrone and N-acetylcysteine treatment

Antioxidant treatment has previously been shown to be neuroprotective in experimental bacterial meningitis. To obtain quantitative evidence for oxidative stress in this disease, we measured the major brain antioxidants ascorbate and reduced glutathione, and the lipid peroxidation endproduct malondialdehyde in the cortex of infant rats infected with Streptococcus pneumoniae. Cortical levels of the two antioxidants were markedly decreased 22 h after infection, when animals were severely ill. Total pyridine nucleotide levels in the cortex were unaltered, suggesting that the loss of the two antioxidants was not due to cell necrosis. Bacterial meningitis was accompanied by a moderate, significant increase in cortical malondialdehyde. While treatment with either of the antioxidants alpha-phenyl-tert-butyl nitrone or N-acetylcysteine significantly inhibited this increase, only the former attenuated the loss of endogenous antioxidants. Cerebrospinal fluid bacterial titer, nitrite and nitrate levels, and myeloperoxidase activity at 18 h after infection were unaffected by antioxidant treatment, suggesting that they acted by mechanisms other than modulation of inflammation. The results demonstrate that bacterial meningitis is accompanied by oxidative stress in the brain parenchyma. Furthermore, increased cortical lipid peroxidation does not appear to be the result of parenchymal oxidative stress, because it was prevented by NAC, which had no effect on the loss of brain antioxidants.

Ascorbate is depleted by smoking and repleted by moderate supplementation: a study in male smokers and nonsmokers with matched dietary antioxidant intakes

BACKGROUND: Lack of reliable dietary data has hampered the ability to effectively distinguish between effects of smoking and diet on plasma antioxidant status. As confirmed by analyses of comprehensive food-frequency questionnaires, the total dietary intakes of fruit and vegetables and of dietary antioxidants were not significantly different between the study groups in the present study, thereby enabling isolation of the effect of smoking. OBJECTIVE: Our objective was to investigate the effect of smoking on plasma antioxidant status by measuring ascorbic acid, alpha-tocopherol, gamma-tocopherol, beta-carotene, and lycopene, and subsequently, to test the effect of a 3-mo dietary supplementation with a moderate-dose vitamin cocktail. DESIGN: In a double-blind, placebo-controlled design, the effect of a vitamin cocktail containing 272 mg vitamin C, 31 mg all-rac-alpha-tocopheryl acetate, and 400 microg folic acid on plasma antioxidants was determined in a population of smokers (n = 37) and nonsmokers (n = 38). The population was selected for a low intake of fruit and vegetables and recruited from the San Francisco Bay area. RESULTS: Only ascorbic acid was significantly depleted by smoking per se (P < 0.01). After the 3-mo supplementation period, ascorbic acid was efficiently repleted in smokers (P < 0.001). Plasma alpha-tocopherol and the ratio of alpha- to gamma-tocopherol increased significantly in both supplemented groups (P < 0.05). CONCLUSIONS: Our data suggest that previous reports of lower concentrations of plasma vitamin E and carotenoids in smokers than in nonsmokers may primarily have been caused by differences in dietary habits between study groups. Plasma ascorbic acid was depleted by smoking and repleted by moderate supplementation.

[In search of strategies for preventing brain damage as a sequela of bacterial meningitis]

Multiplication of bacteria within the central nervous system compartment triggers a host response with an overshooting inflammatory reaction which leads to brain parenchyma damage. Some of the inflammatory and neurotoxic mediators involved in the processes leading to neuronal injury during bacterial meningitis have been identified in recent years. As a result, the therapeutic approach to the disease has widened from eradication of the bacterial pathogen with antibiotics to attenuation of the detrimental effects of host defences. Corticosteroids represent an example of the adjuvant therapeutic strategies aimed at downmodulating excessive inflammation in the infected central nervous system. Pathophysiological concepts derived from an experimental rat model of bacterial meningitis revealed possible therapeutic strategies for prevention of brain damage. The insights gained led to the evaluation of new therapeutic modalities such as anticytokine agents, matrix metalloproteinase inhibitors, antioxidants, and antagonists of endothelin and glutamate. Bacterial meningitis is still associated with persistent neurological sequelae in approximately one third of surviving patients. Future research in the model will evaluate whether the neuroprotective agents identified so far have the potential to attenuate learning disabilities as a long-term consequence of bacterial meningitis.

The potential effect of population development, smoking and antioxidant supplementation on the future epidemiology of age-related macular degeneration in Switzerland

BACKGROUND: Due to the predicted age shift of the population an increase in the number of patients with late AMD is expected. At present smoking represents the only modifiable risk factor. Supplementation of antioxidants in patients at risk is the sole effective pharmacological prevention. The aim of this study is to estimate the future epidemiological development of late AMD in Switzerland and to quantify the potential effects of smoking and antioxidants supplementation. METHODS: The modelling of the future development of late AMD cases in Switzerland was based on a meta-analysis of the published data on AMD-prevalence and on published Swiss population development scenarios until 2050. Three different scenarios were compared: low, mean and high. The late AMD cases caused by smoking were calculated using the "population attributable fraction" formula and data on the current smoking habits of the Swiss population. The number of potentially preventable cases was estimated using the data of the Age-Related Eye Disease Study (AREDS). RESULTS: According to the mean population development scenario, late AMD cases in Switzerland will rise from 37 200 cases in 2005 to 52 500 cases in 2020 and to 93 200 cases in 2050. Using the "low" and the "high" scenarios the late AMD cases may range from 49 500 to 56 000 in 2020 and from 73 700 to 118 400 in 2050, respectively. Smoking is responsible for approximately 7 % of all late AMD cases, i. e., 2600 cases in 2005, 3800 cases in 2020, 6600 cases in 2050 ("mean scenario"). With future antioxidant supplementation to all patients at risk another 3100 cases would be preventable until 2020 and possibly 23 500 cases until 2050. CONCLUSION: Due to age shift in the population a 2.5-fold increase in late AMD cases until 2050 is expected, representing a socioeconomic challenge. Cessation of smoking and supplementation of antioxidants to all patients at risk has the potential to reduce this number. Unfortunately, public awareness is low. These data may support health-care providers and public opinion leaders when developing public education and prevention strategies.

Lifestyle and stroke risk: a review

PURPOSE OF REVIEW: In recent years, many epidemiological studies have given new insights into old and new lifestyle factors that influence the risk of cerebrovascular events. In this review, we refer to the most important articles to highlight recent advances, especially those important for stroke prevention. RECENT FINDINGS: This review focuses on the most recent studies that show the association of environmental factors, nutrition, alcohol, tobacco, education, lifestyle and behavior with the risk of vascular disease, including ischemic stroke and cerebral hemorrhage. The link between air pollution and stroke risk has become evident. Low education levels and depression are established as risk factors. This is also true for heavy alcohol consumption, although moderate drinking may be protective. Active and passive smoking are independent risk factors, and a smoking ban in public places has already reduced cardiovascular events in the short term. Physical activity reduces stroke risk; overweight increases it. However, clinical trials to assess the effect of weight reduction on stroke risk are still lacking. Fruits, vegetables, fish, fibers, low-fat dairy products, potassium and low sodium consumption are known and recommended to reduce cardiovascular risk. Data on omega 3 fatty acid, folic acid and B vitamins are inconsistent, and antioxidants are not recommended. SUMMARY: Stroke can be substantially reduced by an active lifestyle, cessation of smoking and a healthy diet. Both public and professional education should promote the awareness that a healthy lifestyle and nutrition have the potential to reduce the burden of stroke.

REVERSIBLE SUPPRESSION OF NITRIC OXIDE SYSTEM IN ESSENTIAL HYPERTENSION

Despite enormous research in the field of hypertension, its pathophysiology still remains largely unresolved and appears to be multifactorial. In the present communication, we have analyzed the status of nitric oxide (NO) in the patients with essential hypertension and age matched controls. We have found that the levels of NO are lowered in essential hypertension. The normalization of blood pressure by administration of antihypertensive therapy causes rise in the NO level indicating that perturbed NO status in essential hypertension is reversible. Addition of antioxidant to the antihypertensive drugs causes a further, though non significant, rise in the levels of NO, suggesting that antioxidants may be combined with antihypertensive drugs as adjunct in the management of essential hypertension.