[Clinical and metabolic effects of oral contraceptives]. / Efecto clínico y metabólico de los anticonceptivos orales.

The oral contraception most employed, consists in a combination of estrogen and progestin, the main action in the prevention of ovulation through the inhibition of the secretion of luteinizing hormone (LH) and follicle stimulating hormone (FSH). The progestin in combination with estrogen produces an endometrium not receptive to the oocyte implantation and changes tubal, this affects capacitation and acrosomal reaction. Since 1960s up to date the reports made had been established that the OC had been developed adverse effects such as increase concentration of HDL, increase of apolipoprotein B-100, insulin resistance, increase in SHBG, atherogenicity, alteration in the coagulation factors and increase in the risk of venous thromboembolic disease. This work was elaborated with literature search on MEDLINE between 1985 to 1998, with the purpose to search the collateral effects of Oral Contraceptives evaluated by other authors.

Nitric oxide synthesis inhibition suppresses implantation and decreases cGMP concentration and protein peroxidation.

The effect of Nw-nitro-L-arginine on embryonic implantation and cGMP carbonyl group concentration was assessed at the rat implantation site (IS) and non-implantation site (NIS). The intraluminal administration of 25 microg (2.3 mM) of Nw-nitro-L-arginine inhibited implantation in 34.7% and embryo survival (100%), while in addition, decreasing cGMP concentration both at the site (1664.2 +/- 333.8 pmoles/mg of protein for the control and 1321 +/- 384.3 for those treated), as well as at the NIS (1203.7 +/- 200 to 780.2 +/- 168.5). Carbonyl group concentration was considerably less at the implantation site treated with Nw-nitro-L-arginine than in the control (0.062 +/- 0.012 nmoles/mg of protein and 0.45 +/- 0.1, respectively). Nonetheless, the NIS was not significantly different (0.12 +/- 0.04 and 0.15 +/- 0.05). Our results show that a nitric oxide (NO) dependent system parallel to the formation of cGMP and protein peroxidation products is important at the blastocyst implantation site in order for the endometrium to acquire the necessary properties for an adequate receptivity.

[The role of insulin-like growth factor in polycystic ovary syndrome]. / Participación del factor de crecimiento insulinoide (IGF), en el síndrome de ovario poliquístico (SOP).

The partnership the insulin-like growth factor (IGF) in women with polycystic ovary syndrome (PCOS) is characterized by mechanisms underlying alterations in the GH/IGF-1, axis. In the pathogenesis exist a synergism markedly enhanced between IGF-1 and insulin, and IGF-1 with LH to increase androgen production, causing a reduced IGFBPs and SHBG production, the resulting hyperandrogenism, within and outside the ovary, may inhibitor follicular maturation and the biosynthesis of estrogen. At the present, the data suggests up to date paracrine, autocrine as well as endocrine actions in the ovary in normal conditions and the lost of this homeostasis can be followed by neuro-endocrine.

[Nitric oxide as a regulator of hemodynamic changes in pregnancy]. / El óxido nítrico como regulador de los cambios hemodinámicos en la gestación.

Nitric oxide (.NO) produced by the majority of animal cells, has been considered a second messenger, since it is the result of a transduction process induced by a first stimulus. Biochemically, .NO is produced during the conversion of L-arginine to L-citruline by a reaction catalyzed by the enzyme nitric oxide synthetase. Two ixoenzymes have been characterized from this enzyme: a constitutive isoenzyme activated by hormones produced by the endothelial cells and acting on smooth muscle relaxing properties and the other, an inducible isoenzyme whose synthesis is stimulated by cytokines, and produced by macrophages. As pregnancy progresses, the concentrations of .NO, its metabolites, nitrates and nitrites, cGMP and the synthesizing enzyme, nitric oxide synthetase, increase parallelly until reaching a maximum peak before birth. It is considered that .NO is the molecule that maintains the typical vasodilated tone during pregnancy. During preeclampsia, this free radical, as well as its metabolites are found to be significantly decreased, in addition, the administration of .NO donors or of the precursor of L-arginine reverts the vascular abnormalities of this condition. The mechanism of action behind .NO on the vascular endothelium is by its stimulating effect on the enzyme cyclase guanilate, causing an increase in cGMP concentration and the relaxation of the smooth muscle. The nitric oxide generates by macrophages acts as a defense mechanism when linked with other radicals as the superoxide anion (O2).

[Importance of free radicals during the reproduction cycle]. / Importancia de los radicales libres durante el ciclo reproductor.

The peroxidation products, the free radicals, and the antioxidants compounds notable increase during ovulation, implantation, and pregnancy evolution. Superoxide anion (O2-) rise six time more on the proestrous, than on other stages, while its regulation enzyme, the superoxide dismutase (SOD), decreases. The presence of superoxide anion is related with the edema and the cellular proliferation on the estrous. Superoxide anion is also connected with the increase of fluidity and polarity of the membranes during the implantation. As the pregnancy elapse the lipoperoxides products and the antioxidant compounds augment suggesting that lipoperoxides evoke defense mechanism in a way that, at the end of the pregnancy, the antioxidants exceed peroxidative phenomena. By the other hand, the nitric oxide radical has gained great importance during the pregnancy because it is considered one of the most powerful relaxants of smooth muscle. The inhibition of its synthesis provokes similar signs to the preeclampsia and tis administration can revert many vascular alterations. The role of free radicals is not limited to dangerous effects, but it also, in adequate concentrations, includes the as stimulators of grown factors, and participants of the membranes fluidity.

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 the follicular fluid in follicular development, oocyte maturation and spermatic function]. / Participación del líquido folicular en el desarrollo del folículo, la maduración del ovocito y la función espermática.

Follicular fluid (FF) is of great importance in Assisted Procreation Programmes, because it constitutes the micro-environment of the follicle that regulates the development of the oocyte and participates in the capacitation of the spermatozoa. The biochemical composition of FF is influenced by the state of follicle maturation and reciprocally the content of the fluid predicts the success of the subsequent follicular maturation and pregnancy. In most of the species the high concentrations of estradiol are common in the follicles of intermediate maturity, the progesterone in the mature ones and the androgens in the atresics ones. Estradiol concentration is associated with the fertilizing capacity of the oocytes and its metabolites stimulate the progesterone production. Moreover, the FF regulates the action of the gonadotrophins, because it contains factors that help the union of these with its receptor. The FF contributes providing factors that inhibit and stimulate the meiosis. It contains factors that stimulates oocyte maturation, or that block the ability of the cortical granules to modify the components of the pellucid zone. The exposition of spermatozoons with this fluid helps the acrosomal reaction, the spermatic motility and the ovum penetration.

[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.

[Participation of hormones and regulating factors in implantation and development of the fetoplacental unit]. / Participación de hormonas y factores reguladores de la implantación y el desarrollo de la unidad fetoplacentaria.

Although the embryo has a genetic program of its own development in order that development and embryonic differentiation take place, as well as normal gestation, a series of coordinated interactions between embryo and the mother, should be established; which are mediated by chemical messengers, autocrine, paracrine and endocrine. In this study, hormonal participation and regulating factors of implantation, and the feto-placental unit development, are analyzed.

[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.

[Prenatal diagnosis by ultrasonography. A randomized study of 3000 patients]. / Diagnóstico prenatal por ultrasonografía. Estudio aleatorio de 3,000 pacientes.

From January through December, 1990 at Hospital de Ginecoobstetricia Tlatelolco, 3,000 pregnant women were subjected to ultrasonography at random using a real time, B mode apparatus with a 3.5 MHz lineal transducer. Fetal malformation were diagnosed, some of which would have passed undetected in the labor room with consequent delay of treatment and false raise of perinatal morbidity and mortality rates.

[Teratologic effects of benzodiazepines]. / Efectos teratológicos de las benzodiazepinas.

Benzodiazepines are drugs that belong to the group of minor tranquilizers. They derive from the 1-4, benzodiazepine common nucleus that was obtained by chemical synthesis and act upon the GABA receptors increasing their affinity, thus providing them with their tranquilizing, miorelaxing, and anticonvulsant properties. Due to these characteristics they have been used in a wide variety of disorders accompanied by anxiety, hyperexitability, convulsions, and muscular hypertony, as well as during pregnancy and labor. Before using them in pregnant women, the physician should consider the conditions of the product "in uterus" since, according to experimental evidences, benzodiazepines could interfere with embryonary development, mainly with those involved in central nervous system mechanisms causing tissular alterations, retardment in cellular differentiation, and behavioral disturbances. Besides, since the fetus has lower excretion rate than that of the mother, drug concentrations are greater than the therapeutic ones and fetal tolerance to the compound, administered during the last trimester, is reduced, originating abstinence or intoxication syndromes in the newborn. It is concluded that more research is needed to evaluate all the aftereffects caused by using these drugs during pregnancy.

[Implantation of the zygote]. / A propósito de la implantación del cigoto.

In order for implantation to occur, the endometrium must be adequately differentiated, a estate which results from the sequential interaction of progesterone and estrogens, and the local effects of prostaglandins and histamine. Nevertheless, the exact mechanism through which these hormones affect the uterus is not clearly understood. Recently it has been proposed the role of second messengers (cAMP.cGMP, inositol triphosphate and diacylglycerol) in this process. All these messengers are related with the intracellular mechanisms of proteic and steroid hormones action.