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E Absi

Publications and source records attributed to E Absi.

5 recordsLinked to original sources
PubMed2003

Prevention of brain protein and lipid oxidation elicited by a water-soluble oryzanol enzymatic extract derived from rice bran.

BACKGROUND: The antioxidant capacity of rice bran (RB) (due mainly to its gamma-oryzanol content) is very well known. We have recently developed a water-soluble oryzanol enzymatic extract (WSOEE), which shows a greatly increased functionality. AIM OF THE STUDY: The aim of our study is the evaluation of the antioxidant potential of WSOEE in an ex vivo model to compare its protective capacity against oxidative damage by active-oxygen substances and free radicals (mainly the peroxyl radical) to biomolecules (such as proteins and lipids) with that of antioxidants, such as Trolox (a water-soluble derivative of vitamin E), melatonin, and folic acid. METHODS: WSOEE gamma-oryzanol content and composition were determined by HPLC. Free-radical-scavenging capacity was evaluated using the assay based on phycoerythrin fluorescence. Antioxidant capacity against hydroperoxide-caused oxidative injury to proteins and lipids was evaluated using an ex vivo model: a rat brain homogenate. The effectiveness was determined by assessing protein damage (measured as carbonyl group content by Western blot immunoassay) and lipid peroxidation (measured as malondialdehyde content). RESULTS: The WSOEE gamma-oryzanol composition profile was similar to that of RB (cycloartenyl, 24-methylene cycloartenyl, campesteryl, and sitosteryl ferulates), but with two major differences: WSOEE gamma-oryzanol concentration was five times higher than that of RB, and WSOEE was water soluble. WSOEE total antioxidant capacity to trap the peroxyl radical was high, and similar to that of Trolox. The capacity to inhibit lipid peroxidation induced by cumene hydroperoxide in rat brain homogenate yielded a protection similar to that of Trolox. WSOEE also showed the capacity to protect protein from oxidation phenomena in rat brain homogenate, with a behavior similar to that of melatonin. This is of particular importance, since the loss of protein function caused by oxidative modification may affect the activity of enzymes, receptors, and membrane transporters, among other functions. CONCLUSION: WSOEE is a new potential antioxidant agent from rice bran that shows a high free-radical-scavenging capacity and prevents protein oxidation and lipid peroxidation when cells ex vivo are exposed to free radicals.

Animals↗
PubMed2000

Protective effect of melatonin against the 1-methyl-4-phenylpyridinium-induced inhibition of complex I of the mitochondrial respiratory chain.

In the present study, a novel property of melatonin is shown: a protective effect of melatonin on the respiratory chain in isolated rat liver mitochondria and in striatal synaptosomes treated with 1-methyl-4-phenylpyridinium ion (MPP+). The cellular damage caused by MPP+, a compound that produces a Parkinsonian-like syndrome in humans, is the result of the mitochondrial respiration inhibition at the Complex I level and oxidative stress induction. Treatment of mitochondria with MPP+ inhibits the respiration rate. This effect was prevented by the inclusion of melatonin in the incubation mixture. This preventive effect, which is not related to the antioxidative properties of melatonin, seems to be due to the fact that melatonin prevents MPP+ interaction with Complex I. These results suggest that melatonin may protect against the effect of several Parkinsonogenic compounds that are associated with progressive impairment of mitochondrial function and increased oxidative damage.

1-Methyl-4-phenylpyridinium↗
PubMed2000

The endogenous amine 1-methyl-1,2,3,4- tetrahydroisoquinoline prevents the inhibition of complex I of the respiratory chain produced by MPP(+).

The endogenous monoamine 1-methyl-1,2,3,4-tetrahydroisoquinoline has been shown to prevent the neurotoxic effect of MPP(+) and other endogenous neurotoxins, which produce a parkinsonian-like syndrome in humans. We have tested its potential protective effect in vivo by measuring the protection of 1-methyl-1,2,3,4-tetrahydroisoquinoline in the neurotoxicity elicited by MPP(+) in rat striatum by tyrosine hydroxylase immunocytochemistry. Because we know that cellular damage caused by MPP(+) is primarily the result of mitochondrial respiratory inhibition at the complex I level, we have extended the study further to understand this protective mechanism. We found that the inhibitory effect on the mitochondrial respiration rate induced by MPP(+) in isolated rat liver mitochondria and striatal synaptosomes was prevented by addition of 1-methyl-1,2,3,4-tetrahydroisoquinoline. This compound has no antioxidant capacity; therefore, this property is not involved in its protective effect. Thus, we postulate that the preventive effect that 1-methyl-1,2,3,4-tetrahydroisoquinoline has on mitochondrial inhibition for MPP(+) could be due to a "shielding effect," protecting the energetic machinery, thus preventing energetic failure. These results suggest that this endogenous amine may protect against the effect of several parkinsonism-inducing compounds that are associated with progressive impairment of the mitochondrial function.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1995

The demand for primary dental care at a dental teaching hospital, 1989 and 1993.

The demand for, and provision of, primary dental care was investigated in a teaching hospital setting in 1989 and 1993 - a period which saw the introduction of the new dental contract and the publication of the Poswillo report on general anaesthesia and sedation. Five hundred patients who attended the primary care department for the first time at the University of Wales Dental Hospital were interviewed in May/June 1989, and a further 520 patients were interviewed in May/June 1993. Self-referrals increased from 260 patients (52%) in 1989 to 352 patients (68%) in 1993. The proportion of patients who did not have a general dental practitioner (GDP) increased from 32% (160) in 1989 to 39% (202) in 1993. More patients registered with a dentist self-referred in 1993 compared to those in 1989, reportedly because of inability to obtain an appointment with their own GDP (88), rather than because of cost (17). Over the four-year period there was an increase in demand for treatment of early stage (pulpitic) dental infection from 32% to 40%, and a decrease in relation to end-stage infection (dentoalveolar abscess) from 11% to 6%. This 'safety net' role of dental hospitals needs to be taken into account when contracting for services.

Adolescent↗