Comparison between Different Visual Acuity Tests and Validation of a Digital Device.

Purpose: To compare different visual acuity (VA) tests (printed and digital, symbols and letters) and to validate a new device for VA testing called DIVE (Devices for an Integral Visual Examination).

Methods: VA was tested in a wide spectrum of adult people with printed tests (ETDRS and LEA Symbols) and with two implemented tests in DIVE (HOTV and DIVE Symbols). We measured agreement between the different VA tests using the intraclass correlation coefficient and Bland-Altman method.

Optical Quality Variation of Different Intraocular Lens Designs in a Model Eye: Lens Placed Correctly and in an Upside-Down Position.

Introduction: Intraocular lenses (IOLs) may lose their optical quality if they are not correctly placed inside the capsular bag once implanted. One possible malpositioning of the IOL could be the implantation in an upside-down position. In this work, three aspheric IOLs with different spherical aberration (SA) have been designed and numerically tested to analyse the optical quality variation with the IOL flip, and misalignments, using a theoretical model eye.

Doxorubicin induces ceramide and diacylglycerol accumulation in rat hepatocytes through independent routes.

Doxorubicin (DOX) is a potent anticancer drug, whose clinical use is limited due to its toxicity. This toxicity has been associated with free radicals generated during the drug metabolism. We previously found that DOX increased the intracellular diacylglycerol (DAG) levels at 1h in isolated rat hepatocytes, probably by mobilizing choline-enriched phospholipids.

Ferrylmyoglobin impairs secretion of VLDL triacylglycerols from stored intracellular pools: involvement of lipid peroxidation.

Ferrylmyoglobin (ferrylMb) may play a major role in vivo under certain pathological conditions. Preliminary experiments showed that ferrylmyoglobin induced a mild oxidative stress in rat hepatocytes, mainly reflected by early lipid peroxidation. One of the major functions of hepatocytes is the synthesis, secretion and distribution of lipids to other cells.

Pro-oxidant and antioxidant potential of catecholestrogens against ferrylmyoglobin-induced oxidative stress.

Ferryl heme proteins may play a major role in vivo under certain pathological conditions. Catecholestrogens, the estradiol-derived metabolites, can act either as antioxidants or pro-oxidants in iron-dependent systems. The aim of the present work was (1) to determine the effects of ferrylmyoglobin on hepatocyte cytotoxicity, and (2) to assess the pro/antioxidant potential of a series of estrogens (phenolic, catecholic and stilbene-derived) against ferrylmyoglobin induced lipid peroxidation in rat hepatocytes.

tert-Butyl hydroperoxide-induced lipid signaling in hepatocytes: involvement of glutathione and free radicals.

tert-Butyl hydroperoxide (TBHP) mobilizes arachidonic acid (AA) from membrane phospholipids in rat hepatocytes under cytotoxic conditions, thus leading to an increase in intracellular AA, which precedes cell death. In the present work, the involvement of lipid peroxidation, thiol status, and reactive oxygen species (ROS) in the intracellular AA accumulation induced by 0.5 mM TBHP was studied in rat hepatocytes.

17beta-estradiol affects in vivo the low density lipoprotein composition, particle size, and oxidizability.

The aim of this study was to explore the possible modifications induced by 17beta-estradiol (E(2)) in vivo on low-density lipoprotein (LDL) lipid composition, particle size, and oxidizability. For this purpose, women were recruited from an in vitro fertilization program, ranging their plasma E(2) levels from less than 12 pg/ml to more than 2000 pg/ml at the end of the treatment. The LDL lipid constituents were analyzed by thin layer chromatography and image analysis, and the LDL diameter was calculated from the lipid data.

Antioxidant activities of estrogens against aqueous and lipophilic radicals; differences between phenol and catechol estrogens.

Natural estrogens have much greater radical-scavenging antioxidant activity than has previously been demonstrated, with activities up to 2.5 times those of vitamin C and vitamin E. The biological significance of this finding remains to be elucidated.

In vitro inhibition by estrogens of the oxidative modifications of human lipoproteins.

Estrogens exert protective actions against atherosclerosis, part of these effects having been ascribed to their antioxidant properties. The aim of this work was to assess the ability of estrogens to prevent the oxidative modifications of low density lipoproteins (LDL) and other plasma lipoprotein fractions whose relationship with atherosclerosis has been less studied. For this purpose, different estrogen compounds were used: natural and synthetic estrogens, and catecholestrogens.

Inhibition by estrogens of the oxidant-mediated mobilization of arachidonic acid in hepatocytes.

Oxidative stress is associated with alterations in arachidonic acid (AA) metabolism. The present work was performed to assess the effect of the oxidant tert-butyl hydroperoxide on the release of AA from rat hepatocytes, and the possible preventive actions of estrogens on this effect. The exposure of [14C]-prelabeled cells to tertbutyl hydroperoxide produced the mobilization of [14C]-AA from hepatocyte lipids, both an intracellular [14C]-AA accumulation and an increased release of [14C]-products into the medium being observed.

Cytoprotective actions of estrogens against tert-butyl hydroperoxide-induced toxicity in hepatocytes.

Estrogens are effective antioxidants in diverse biological systems. Despite their antioxidant activities, it is not known yet whether estrogens prevent or alleviate liver toxicity induced by oxidative stress. In the present work, we studied this possibility by examining in vitro the protective potential of different estrogen compounds (17beta-estradiol, 2-hydroxyestradiol, and diethylstilbestrol) against tert-butyl hydroperoxide-induced hepatocyte damage.

Antioxidant action of estrogens in rat hepatocytes.

The in vitro addition of 17 beta-estradiol (0-100 microM) to isolated rat hepatocytes efficiently prevented cellular lipid oxidation induced by the Fe(III)/ADP complex. 17 beta-estradiol was found to be less effective than its metabolic derivative 2-hydroxyestradiol. The presence of specific inhibitors of cytochrome P450 activity significantly diminished the antioxidant capacity of estradiol.

Regulation of bile acid synthesis by estradiol and progesterone in primary cultures of rat hepatocytes.

We have used primary monolayer cultures of hepatocytes from rats fed standard and cholestyramine-diet to study the effects of 17 beta-estradiol and progesterone on the activity of cholesterol 7 alpha-hydroxylase (EC 1.14.13.

Effects of estrogens on the redox chemistry of iron: a possible mechanism of the antioxidant action of estrogens.

The preventive effects of estrogens on FeSO4-induced lipid peroxidation are closely correlated with their inhibition of Fe(II) oxidation during peroxidation. Estrogens affected the redox status of iron in aqueous solution with varying degrees of effectiveness. 2-Hydroxyestradiol substantially decreased the oxidation of Fe(II) and was the most potent Fe(III) reductant.

Inhibition of microsomal cholesterol ester hydrolase by okadaic acid in isolated rat hepatocytes.

Okadaic acid, a potent and specific inhibitor of protein phosphatases 1 (IC50 10-20 nM) and 2A (IC50 0.05-2 nM) caused early and sustained inhibitions of microsomal cholesterol ester hydrolase activity in hepatocyte suspensions. The changes in the kinetic properties of the esterase and its response to exogenous alkaline phosphatase and cyclic AMP-dependent protein kinase after cell exposure to 1 microM or 1 nM okadaic acid differed markedly among themselves, which suggests the involvement of both protein phosphatases 1 and 2A in the regulation of the microsomal hydrolysis of cholesterol esters.

Protective effect of estrogens and catecholestrogens against peroxidative membrane damage in vitro.

The antioxidant effects of natural estrogens (estrone, E1; 17 beta-estradiol), synthetic estrogens (17 alpha-ethynylestradiol, EE2; mestranol, MES; diethylstilbestrol, DES) and catecholestrogens (2-hydroxyestradiol; 4-hydroxyestradiol, 4-OHE2) on lipid peroxidation induced by different means in rat liver microsomes were investigated. The extent of lipid peroxidation was determined by measuring thiobarbituric acid reactive substances. Prooxidants included Fe3+/ADP/reduced NADPH, Fe2+/ascorbate, tert-butyl hydroperoxide (t-BOOH) and 2,2'-azobis(2-amidinopropane) (AAPH).

Effect of estradiol and progesterone on cholesterol 7 alpha-hydroxylase activity in rats subjected to different feeding conditions.

The regulation of cholesterol 7 alpha-hydroxylase activity by estradiol and progesterone was investigated in liver microsomes isolated from rats fed standard diet, either ad libitum or fasted for 24 h, and diet containing the bile acid sequesterant cholestyramine. Differential effects were observed when the direct action of estradiol and progesterone on microsome preparations was examined. Cholesterol 7 alpha-hydroxylase activity was inhibited by progesterone in a dose-dependent way to almost complete abolition; similar patterns of declines were found in the three feeding groups under study.

Antioxidant effects of estradiol and 2-hydroxyestradiol on iron-induced lipid peroxidation of rat liver microsomes.

In the present study, the antioxidant effects of estradiol (E2) and 2-hydroxyestradiol (2-OHE2) on microsomal lipid peroxidation induced by Fe3+/ADP/NADPH and Fe2+/ascorbate are described. The extent of lipid peroxidation was measured by thiobarbituric acid reactive substances (TBARS) detection, low-level chemiluminescence, and oxygen consumption. 2-OHE2 had a potent antioxidant activity, which in all cases was higher than that of E2.

Regulation of rat liver microsomal cholesterol ester hydrolase by reversible phosphorylation.

The regulation of neutral cholesterol ester hydrolase activity by changes in its phosphorylation state was studied in rat liver microsomes. Treatment with cAMP-dependent protein kinase resulted in increased enzyme activity, which was further enhanced by the addition of cAMP and MgATP. Consistent activations were also achieved with MgCl2 and MgATP, the magnesium effect being abolished by ethylenediaminetetraacetic acid and adenosine triphosphate.

Divalent metal ions as modulators of rat liver microsomal cholesterol esterase.

The regulatory properties of the divalent metal ions Mg2+, Ca2+ and Mn2+ on the activity and kinetic behaviour of rat liver microsomal cholesterol esterase were studied in vitro. Mg2+ and Ca2+ exhibited similar concentration and preincubation time-dependent increases in esterase activity, with maximal stimulation at a concentration of 2 mM. However, Mn2+ had no effect at this concentration but displayed a potent inhibitory effect at concentrations above 20 mM.