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.

The localization of PI and PIP kinase activities in the sea urchin egg and their modulation following fertilization.

Phosphatidylinositol phosphate (PIP) kinase activity is localized to the cortical region of unfertilized sea urchin eggs, while phosphatidylinositol (PI) kinase activity is found in both cortical and noncortical membranes. Following fertilization PIP kinase activity decreases, while PI kinase activity remains unchanged. The selective loss of PIP kinase activity is related to cortical granule exocytosis since the drop in activity does not occur if exocytosis is prevented by high hydrostatic pressure. When isolated cortices are exposed to elevated concentrations of calcium, both the PI and PIP kinase activities increase, suggesting that activation of these enzymes might occur when calcium levels increase within the fertilized egg prior to cortical granule exocytosis. The polyamine spermine also stimulates the formation of phosphatidylinositol bisphosphate at physiological concentrations.

Cyclic AMP and cyclic GMP in the implantation site of the rat.

Endometrial differentiation of the implantation site (IS) is regulated by hormonal and local influences (egg). To better understand the possible participation of cyclic nucleotides in this process, we measured cAMP and cGMP by RIA in IS of the rat on day 6 of pregnancy. IS showed an increase of both nucleotides (3.54 and 0.57 pmoles/mg DNA) when compared with the remaining endometrium (NIS) (2.70 and 0.30). The cAMP/cGMP ratio did not change significantly. We also found an increase in the proteins/mg DNA ratio (12.04 in IS vs 10.63 in NIS) and in the hydration of IS. Our hypothesis is that together these two nucleotides function as a monodirectional system in which they act cooperatively as positive effectors of different sequential steps in the overall process of implantation.

Inhibition of implantation by the intrauterine administration of phospholipases in the rat.

Phospholipases A2 and C (93 and 500 mU) were administered to uterine horns of Long-Evans adult rats during the first five days of pregnancy. As control material, saline (0.15 M) was administered to contralateral uterine horns. The animals were sacrificed on the ninth day of pregnancy, the uterine horns were removed and the number of implanted embryos were counted. Both horns were examined with light and electron microscopes. For electron microscopy, Ruthenium red was used to visualize possible changes of the outer coat (glycocalix) of the plasma membrane of endometrial epithelial cells. Implantation was inhibited when phospholipases A2 and C were administered during the first three days of pregnancy. Ultrastructural modifications included decrease of glycoproteins as demonstrated by diminution of the Ruthenium red staining that may indicate a decrease in the negative surface charges of endometrial surface epithelium.

Prostaglandinas y reproduccion: I. Ovulacion, transporte e implantacion. / Prostaglandins and reproduction: I.Ovulation, transport and implantation

Se presenta un analisis sobre la participacion de las diversas prostaglandinas en algunos procesos reproductivos del mamifero, enfocandose este estudio, fundamentalmente a la interpretacion de la funcion de las prostaglandinas en la ovulacion, mantenimiento del cuerpo luteo, transporte del cigoto, asi como a la regulacion que ejercen estas hormonas en el proceso de implantacion

Prostaglandinas y reproducion: II. El embarazo y el parto / Prostaglandins and reproduction: II. Pregnancy and birth

Las investigaciones para comprender la participacion de las prostaglandinas (PGs) en los procesos repoductivos de direntes mamiferos han demostrado que estas hormonas influyen en la regulacion de la funcion ovarica, el transporte del ovulo y del cigote, la implantacion, el embarazo y el parto. En el embarazo el cuerpo luteo es regulado por factores luteoliticos y luteotropicos. Existen evidencias experimentales de que la PGF2 alfa, de origen uterino es el factor luteolitico. Durante todo el embarazo PGF2 y PGF2 alfa son capaces de inducir contracciones uterinas.Es posible que la fuente principal de esta PGs sean la membrana fetal y la decidua y también que sean mediadoras de la accion oxitocida

Reduction capacity on nitroblue tetrazolium (NBT) of the normal human spermatozoa.

Experimental conditions were determined to find out if washed spermatozoids from fertile, health donors are capable of nitroblue tetrazolium (NBT) reduction in a similar way (although in the absence of a substrate) to that of leukocytes. Formazan blue formation obtained suggest the participation of the NADH oxidoreductase mitochondrial enzyme. The sperm capacity for NBT reduction might be take as a reflection of human sperm metabolic capacity. Our results seem to be useful for comparison of reduction (metabolic) capacity of normal sperms with that of individuals with fertility problems.

Capacidad reductora del espermatozoide humano normal sobre el NBT (nitroazul de tetrazolio). / Reduction capacity on nitroblue tetrazolium (NBT) of the normal human spermatozoa

Se determinaron las condiciones experimentales para juzgar si los espermatozoides lavados de varones sanos y fecundos tienen la capacidad de reducir el nitroazul de tetrazolio (NBT) de manera semejante (aunque en ausencia de algun substrato) a como lo hacen los leucocitos. La produccion del color azul de formazan obtenido sugiere la participacion de la enzima mitocondrial oxidoreductasa del NADH.Esta capacidad del espermatozoide hacia la reduccion del NBT podria tomarse como un reflejo de la capacidad metabolica del espermatozoide humano. Nuestros resultados parecen utiles para comparar la capacidad reductora (metabolica) de los espermatozoides normales con la de los obtenidos de sujetos que cursan con problemas de fecundidad

Similar effects of prolactin and dbcAMP upon human spermatozoa metabolism.

Studies were carried out of the effects of prolactin (0.5-1.0 mU) and 3'5' dibutyryl cyclic AMP -(dbcAMP) (100-500 ng) on oxygen uptake and (U-14C) glucose and (1-14C) acetate utilization by human spermatozoa. Both molecules induce a significant increase (P < 0.01) in oxygen uptake when acetate, glucose, pyruvate and lactate were used as substrates, although differences were noted in the induction effect depending on the substrate used (Tukey's multiple comparisons after ANOVA) (P < 0.01). The production of 14CO2 from glucose and labelled acetate was also statistically increased (P < 0.01) by prolactin (from 15.15 to 25.32 nmoles CO2/hour/10(8) sperm cells) as well as by dbcAMP (15.15 to 34.95 nmoles CO2/hour/10(8) sperm cells). From these results we conclude that the activator effects of prolactin and dbcAMP on human spermatozoa with respect to the studied parameters are similar and that prolactin may be an activator of spermatic adenylyl cyclase.