Oxidative modifications of foetal LDL-c and HDL-c lipoproteins in preeclampsia.

BACKGROUND: Oxidative modifications have been observed in lipids and proteins in lipoproteins isolated from women with preeclampsia. Thus, newborns could also be susceptible to this damage directly through their mothers. In this study, we evaluated the oxidative profile of LDL-c and HDL-c lipoproteins isolated from the umbilical cord from newborns born to women with preeclampsia. METHODS: Thirty newborns born to women with preeclampsia and thirty newborns born to women with healthy pregnancies were included. Lipid-damage biomarkers, including conjugated dienes, lipohydroperoxides and malondialdehyde, were measured. The reduction of nitroblue tetrazolium, formation of dityrosines, and carbonylation of proteins were assessed as indicators of protein damage. The protective activity of paraoxonase-I on HDL-c particles was evaluated. The total antioxidant capacity and lipid profiles were quantified in plasma. Data were analysed using Student's t-tests and Pearson correlation coefficients. RESULTS: Compared with the control group, the preeclampsia group had an increase in the percentage of lipid damage in both lipoproteins. There was an increase of 23.3 and 19.9% for conjugated dienes, 82.4 and 21.1% for lipohydroperoxides, and 103.8 and 51.5% for malondialdehyde in LDL-c and HDL-c, respectively. However, these infants did not show evident damage in protein oxidation. The activity of the enzyme paraoxonase-I was decreased by 36.2%; by contrast, the total antioxidant capacity was increased by 40% (protein) and 28.8% (non-protein). CONCLUSIONS: The oxidative modifications that occur in HDL-c and LDL-c isolated from newborns from women with preeclampsia are mainly caused by lipoperoxidation processes related to evident paraoxonase-I inactivation. The absence of protein damage is likely linked to an increase in total antioxidant capacity. Therefore, antioxidant support could be helpful in reducing oxidative stress in mother/newborn dyads.

Oxidative profiles of LDL and HDL isolated from women with preeclampsia.

BACKGROUND: Oxidative stress causes biochemical changes in lipids and proteins; these changes can induce damage to the vascular endothelium and create maternal complications that are characteristic of preeclampsia. In this study, we evaluated the oxidative profile of lipoproteins isolated from women with preeclampsia. METHODS: Thirty women diagnosed with preeclampsia and thirty women without preeclampsia were included in the study. Lipid-damage biomarkers, including conjugated dienes, lipohydroperoxides and malondialdehyde, were measured. The reduction of nitroblue tetrazolium, the formation of dityrosines, and the carbonylation of proteins were assessed as indicators of protein damage. The protective activity of HDL-c was evaluated by the paraoxonase-I activity present on the HDL-c particles. Serum lipid profiles were also quantified in both groups. Data were analysed using Student's t test and the Pearson correlation coefficient. RESULTS: Our results demonstrated in PE women evident oxidative changes in the lipids and proteins in HDL-c and LDL-c particles and the activity of the antioxidant enzyme PON-I decreased 59.9%. HDL-c exhibited self-defence, as demonstrated by the negative correlation between paraoxonase-I activity and the formation of lipohydroperoxides in HDL-c (r = -0.3755, p < 0.005). CONCLUSIONS: LDL-c and HDL-c isolated from women with preeclampsia show oxidative damage to lipids and proteins. We propose an oxidative profile based on the oxidation levels indicated by each of the markers used. We also found that paraoxonase-I is inactivated in the presence of lipohydroperoxides. Antioxidant support might be helpful to reduce oxidative stress in patients with preeclampsia. Further investigations are necessary to define the association between antioxidant activities and preeclampsia.

Escherichia coli-induced temporal and differential secretion of heat-shock protein 70 and interleukin-1ß by human fetal membranes in a two-compartment culture system.

INTRODUCTION: Escherichia coli is recognized as an etiological bacteria associated with chorioamnionitis and the preterm premature rupture of fetal membranes. This pathological condition induces pro-inflammatory cytokines and degradative metalloproteinases, which are considered biological markers secreted in an acute stage of infection. Heat-shock proteins (HSPs) are an important component of the innate immunity response and are found in different pathological conditions. They have not been previously measured in human fetal membranes in response to infectious conditions. We hypothesized that the choriodecidual tissue and amniotic epithelium secreted temporal and differential Hsp-60, Hsp-70, and interleukin (IL)-1ß mediated by E. coli infection. METHODS: Fetal membranes were mounted in a two-compartment culture system and infected with two passes of live E. coli at different doses (10², 104, 105, and 106 colony-forming units (CFU)/mL) and intervals of incubation (3, 6, and 24 h). The culture medium was collected, and Hsp-60, Hsp-70, and IL-1ß were assessed using the enzyme-linked immunosorbent assay (ELISA) method. RESULTS: After 3 and 6 h of infection, E. coli induced an increase in Hsp-70 secretion in the choriodecidual tissue. However, after 24 h of incubation, Hsp-70 was downregulated and we observed an increase in IL-1ß secretion. By contrast, E. coli induced a lower Hsp-60 secretion in the amnion compared to Hsp-70. DISCUSSION: Human fetal membranes responded actively to E. coli infection, with an increase in Hsp-70 during the first hours of infection. After 24 h, there was an increase in the liberation of IL-1ß.

Hyperglycemia induces apoptosis and p53 mobilization to mitochondria in RINm5F cells.

The mechanisms related to hyperglycemia-induced pancreatic beta-cell apoptosis are poorly defined. Rat insulin-producing cells (RINm5F) cultured in high glucose concentrations (30 mM) showed increased apoptosis and protein p53 translocation to mitochondria. In addition, hyperglycemia induced both the disruption of mitochondrial membrane potential (Delta psi (m)), and an increase in reactive oxygen species (ROS), as shown by fluorescence changes of JC-1 and dichlorodihydrofluorescein-diacetate (DCDHF-DA), respectively. The increased intracellular ROS by high glucose exposure was blunted by mitochondrial-function and NADPH-oxidase inhibitors. We postulate that the concomitant mobilization of p53 protein to the mitochondria and the subsequent changes on the Delta psi (m), lead to an important pancreatic beta-cell apoptosis mechanism induced by oxidative stress caused by hyperglycemia.

Glucose induces a Na(+),K(+)-ATPase-dependent transient hyperpolarization in human sperm. I. Induction of changes in plasma membrane potential by the proton ionophore CCCP.

When human sperm was incubated in medium deprived of glucose, glucose restoration caused a transient hyperpolarization of the plasma membrane. This hyperpolarization was also induced by fructose but not by 2-deoxyglucose, a substrate that cannot be metabolized. The hyperpolarization was inhibited by NaF, a glycolysis inhibitor, but not by mitochondrial inhibitors (cyanide, rotenone and antimycin), suggesting that it depended on glycolysis. Furthermore, the hyperpolarization was still induced in medium containing a high concentration of KCl and was insensitive to the K(+) channel blocker TEA and the Cl(-) channel blocker niflumic acid, but it was blocked by ouabain. This suggested that upon glucose addition, there was an increase in the concentration of ATP, that in turns increased the Na(+),K(+)-ATPase activity. Since this pump is electrogenic (2K(+)/3Na(+)) the plasma membrane hyperpolarized. On the other hand, CCCP, a proton ionophore, inhibited the hyperpolarization induced by glucose. When CCCP was added to glucose-treated hyperpolarized sperm, it caused a depolarization that triggered a Ca(2+) influx sensitive to nickel, an inhibitor of voltage-dependent calcium channels. Moreover, CCCP caused hyperpolarization in sperm incubated in medium without calcium, a known condition that depolarizes sperm. This indicated that CCCP induced proton permeability in the plasma membrane that was able to change the membrane potential to a value corresponding to the E(H) and that was also able to clamp it, so that it prevented the hyperpolarization induced by glucose.

Effect of nitric oxide releasers on some metabolic processes of rabbit spermatozoa.

The authors investigated the possible effect of nitric oxide (NO) releasers (the free radical form of nitrogen monoxide, which control some functions of many cells) on rabbit spermatozoa. A significant (P < .01) increment was found in the percentage of the acrosome reaction in rabbit spermatozoa incubated for 30-60 min in presence of the NO releasers sodium nitroprusside (SNP) and N-acetyl-S-nitroso cysteine (NACysSNO), but not with S-nitroso cysteine (CysSNO). This effect was reverted or lowered when the NO scavenger HbO2 was included in the medium. The effects of SNP and NACysSNO on acrosome reaction do not appear to be related to glucose utilization, viability, or lipid peroxidation.

Oxidation of gonadotrophin (PMSG) by oxygen free radicals alters its structure and hormonal activity.

The effect of oxygen free radicals produced by the Fenton reaction was used to induce oxidation and other structural changes in pregnant mare serum gonadotrophin (PMSG). Modifications in the spectrophotometric scan, an increase in exposed carbonyl groups, and the ability to reduce nitroblue tetrazolium, was achieved by the oxidized hormone when compared to the control PMSG. PMSG loses its biological activity when coming in contact with the free-radical generating system. This lack of activity is manifested as a loss of ovulation and a decrease in the weight of the ovaries and uterus. It was demonstrated that oxygen free radicals can induce structural and biological changes in the gonadotrophin.

Voltage-dependent calcium influx in human sperm assessed by simultaneous optical detection of intracellular calcium and membrane potential.

There are several physiological and pharmacological evidences indicating that opening of voltage dependent calcium channels play a crucial role in the induction of the acrosome reaction in mammalian sperm. In mature sperm, physiological inductors of the acrosome reaction such as ZP3, a zona pellucida protein, and the steroid hormone progesterone, induce depolarization and calcium influx, which are required for the acrosome reaction. In this paper, we describe a voltage-dependent calcium influx present in human sperm. We report an experimental procedure that allows measurement of intracellular calcium and membrane potential simultaneously using the fluorescent dyes DiSC3(5) and Fura-2. We found that in human uncapacitated sperm, depolarization induces a nifedipine-insensitive calcium influx that, in most cases, was transient. Calcium influx was observed in the range of -60 to -15 mV (the range tested). At resting membrane potential (around -40 mV), potassium addition depolarized and induced calcium influx, but when the depolarization was preceded by a hyperpolarization (induced with valinomycin), calcium influx was remarkably enhanced, suggesting that at -40 mV, channels are in a putative inactivated state. When sperm was incubated in medium without calcium, calcium restoration caused calcium influx that depended on voltage, and decayed between 1 and 2 min after depolarization. Unlike ram, mouse or bovine sperm, in which an alkalinization is required to induce calcium influx with potassium, the voltage-dependent calcium influx observed in human sperm did not require an increase in internal or external pH. However, we observed that ammonium, which increases intracellular pH, enhanced the voltage-dependent calcium influx about 90%. Furthermore, depolarization by itself caused a small increase in intracellular pH suggesting that pH can be regulated by membrane potential in human sperm.

Participation of oxygen-free radicals in the oxido-reduction of proteins.

Recent studies have focused attention on the possible role of active oxygen species on protein damage and degradation. The reactions of free radicals on biomolecules are important in physiology and pathology. A number of systems that generate free radicals catalyze the oxidative modification of proteins in two species: protein peroxides, which can consume important antioxidants; and protein-bound reducing moieties, which can reduce transition metals, and may enhance their activity in radical reactions. Protein oxidation also contributes to the pool of damaged enzymes and accumulation of abnormal and damaged proteins, which increases during aging and in various pathological states, such as atherosclerosis, cancer, etc.

[Role of nitric oxide in the reproductive function in mammals]. / Participación del óxido nítrico en la función reproductora de mamíferos.

NO, is a physiologic messenger involved in many cellular functions widely research at present time. The purpose of this review, is to emphasize the No contribution at reproduction level one aspect more recently on study, a field where it remains yet, many questions to ask.

[Communication of gametes at distance. Chemotaxis and chemokinesis in spermatozoa in mammals]. / Comunicación de gametos a distancia. Quimiotaxis y quimiocinesis del espermatozoide en mamíferos.

The communication to distance is controlled chemically by the egg and the spermatozoa as part of the fertilization process, it has been studied intensily in invertebrate animals with outside fertilization. However studies with mammals offers a field of great interest. The chemoattractant from mammals spermatozoa include peptides or protein with a molecular weight of 1-20 KDa, hormones like progesterone, oxitocin, adrenalin and receptors on the spermatozoa head which are associated with the Guanylyl cyclase enzyme and G proteins, as well as other as like odorant receptor, rhodoopsin kinases and arresting. Chemotaxis allow us to understand the fertilization in human and also develop program for assisted reproduction. It is very important in the contraception.

[Oxygen reactive species in spermatozoa]. / Especies reactivas de oxígeno en el espermatozoide.

The free radicals of oxygen are chemical species of this element formed through enzymatics and non enzymatics reactions and they have been involved in many pathologic and physiologic processes. The most reactive chemical species of oxygen are the hydrogen peroxide and the free radicals frecuradils superoxide anion, hydroxil and free radical, this one being the most reactive. The mammalian spermatozoa, including the human, produce free radicals of oxygen and hydrogen peroxide; although this cell normally has enzymatic mechanics to protect itself from the possible damage of this toxic agents. In spite of, the spermatozoa is susceptible to "oxitative stress", and maybe it is due to the high concentrations of insaturated fatty acids. This fact may be important in the pathology of certain types of masculine infertility like oligozoospermia, because it displays a discontrol production of oxygen reactive species in the spermatozoa.

[Molecular systems in cellular interactions. II: Embryonal implantation in mammals]. / Sistemas moleculares en las interacciones celulares. II: Implantación embrionaria en mamíferos.

In the present paper we consider the molecular mechanisms for cell recognition and cell adhesion on embryo implantation in mammals. In mammalian embryo implantation, the cellular interactions are complex, because several kinds of cells are involved: embryo trophoblast cells interact with several uterine cells and their respective extracellular matrices, participating lactosaminoglycans, integrins, cadherins and galactosyl transferases.

[Molecular systems in cellular interactions. I. Fertilization iin mammals]. / Sistemas moleculares en las interacciones celulares. I: Fecundación en mamíferos.

Multicellular organisms require diverse mechanisms of cellular recognition in order to work integrally. In the present paper we consider the molecular mechanisms for cell recognition and cell adhesion on fertilization of mammalian egg. Several surface proteins of spermatozoa (galactosyl transferase, proteases, glycosidases and lectins), recognize and bind zona pellucida glycoproteins of egg, a necessary condition prior to fertilization.

[Mechanism of action of steroid hormones. I. Estrogens]. / Mecanismo de acción de hormonas esteroides. I. Estrógenos.

The steroid hormone are very versatile molecules: although they are related among them by their chemical structure, they have very diverse functions and including antagonic. Their action mechanism is not completely cleared. The estrogens participate in the regulation of practically all the reproductive and sexual events of the female, although the intracellular actions by which they take place are not well known and the proposed models do not adequately satisfy the questions. Currently it is accepted the existence of a cytoplasmic and/or nuclear receptor, without explaining satisfactorily how the hormones come to the nucleus. The endocrine events that are rapidly expressed (seconds) are due to a possible interaction with cellular membrane. The purpose of this review is to analyze and concilliate the reported data on the mechanism of action of estrogens.