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R Fierro

Publications and source records attributed to R Fierro.

12 recordsLinked to original sources
PubMed1998

Evaluation of human sperm acrosome reaction and viability by flow cytometry.

We report in this work a quantitative procedure developed to evaluate the acrosomal reaction and vitality of human spermatozoa, with three color staining simultaneously. Twenty normal human sperm were labeled with GB24 monoclonal antibody, a fluorescein isothiocyanate conjugated lectin and propidium iodide (supravital stain). Four conjugated lectins were investigated: WGA, Con-A, PNA and UEA-1. Acrosome reaction was induced with calcium ionophore A-23187. Analyses were made by flow cytometry and electron microscopy. A high percentage of spermatozoa that stained with propidium iodide was found. The results of four lectins show an interaction between GB24 and lectin binding. Significant differences of fluorescence index were obtained between the samples with calcium ionophore A-23187 and the samples without it. The WGA-GB24 association shows an independent behavior and this may depend on the fact that WGA binds to the cytoplasmic membrane of human spermatozoa and GB24 antibody bind inner acrosome membrane. Using Con-A, PNA and UEA-I a crowded staining is likely to occur because these lectins and GB24 antibody mainly bind to acrosome membranes, and our results then show a close relation.

Acrosome Reaction↗
PubMed1996

Large-sample analysis for a stochastic epidemic model and its parameter estimators.

This paper considers the simplest stochastic model for the spread of an epidemic in a closed, homogeneously mixing population. Approximate methods are presented for calculating the probability distribution of the epidemic size (i.e. number of infected individuals). In fact, a functional central limit theorem and a large deviation principle for the epidemic size when the population increases are shown. These results enable us to both obtain a global approximation for the epidemic size and study asymptotic properties of other random variables depending on the complete history of the epidemic. As an application of our results, we derive two sequences of estimators for the contact rate and analyze their asymptotic behaviour.

Disease Outbreaks↗
PubMed1994

Inhibition of pig oocyte in vitro fertilization by the action of components of the zona pellucida.

The aim of the present study was to determine whether the previous addition of porcine zona pellucida (ZP) components to spermatozoa of the same species has an inhibitory effect on in vitro fertilization (IVF). Boar spermatozoa were exposed to whole porcine solubilized zona pellucida (SZP), ZP glycoproteins (55 kDa and 90 kDa) and peptides (37 kDa, 40 kDa and 68kDa). Doses tested were 40, 70 and 100 mug/ml. In vitro fertilization was clearly inhibited by each component when the oocytes were compared with those fertilized with untreated spermatozoa. All the components had an effect in a dose dependent manner.

Journal Article↗
PubMed1986

Vascular injury following disc surgery.

The case of a patient who suffered a vascular injury following lumbar disk surgery is presented. She presented to the emergency department for evaluation of hypotension and congestive heart failure, which occurred acutely several days after her surgery. At angiography, a large A:V fistula was demonstrated between the aorta and vena cava. The diagnosis and pathophysiology of this complication of lumbar disc surgery is discussed.

Adult↗
PubMedDate not supplied

Acrosome reaction in fertile and subfertile boar sperm.

The main purpose of sperm evaluation is to predict its fertilizing ability. However, basic sperm test results show a low correlation with fertilizing ability. The purpose of this study was to determine whether there is an association between acrosome reaction (AR) and the incidence of subfertility of normal sperm boar. The production records of 22 farms were analyzed to identify boars with low fertility and/or prolificity, classified as subfertile. Twenty-two subfertile boar semen samples were analyzed and compared with 51 samples of fertile boars. Sperm were capacitated during 4 h at 39 degrees C. viability was determined by bisbenzimide (Hoechst-33258) staining. Acrosome reaction was assessed with fluorescein isothiocyanate conjugated Pisum sativum agglutinin. The percentage of spontaneous acrosome reaction (SAR) was not significantly different in fertile (4.5%) and subfertile boars (4.75%) (p > .05). Nevertheless, the percentage of progesterone-induced acrosome reaction (IAR) was significantly lower in subfertile boars (5.75%) as compared with fertile boars (10%) (p < .01). These results suggest that assessment of IAR in vitro may be a useful parameter to identify subfertility in boars.

Acrosome Reaction↗
PubMedDate not supplied

Expression of lectin receptors on the membrane surface of sperm of fertile and subfertile boars by flow cytometry.

Studies suggest that carbohydrates are important in different stages of fertilization. Plasma membrane changes accompanying in vitro capacitation and acrosome reaction (AR), such as removal or appearance of specific glycoproteins, have been studied using lectins that bind specifically to carbohydrate residues. In specialized artificial insemination farms and semen production centers, identification of boars with decreased fertilization ability (subfertility) is a newborn necessity. This investigation is a sequential study to determine the kinetics of surface carbohydrates turnover during in vitro capacitation and AR in fertile and subfertile boar sperm. Flow cytometry determinations of the binding of three FITC-labeled lectins were assessed. WGA binding was significantly lower in fresh, capacitated, and acrosome-reacted sperm of subfertile boars than in fertile boars. Con-A binding was not significantly different in fresh sperm of fertile and subfertile boars. However. Con-A labeling in capacitated, and acrosome-reacted sperm differed significantly in both groups. UEA binding increased only in capacitated sperm of subfertile boars. These findings could be used as indicators of capacitation and AR and may also be a good indicator of sperm fertilizing ability in boars.

Acrosome Reaction↗
PubMedDate not supplied

Expression of IL-2alpha and IL-2beta receptors on the membrane surface of human sperm.

Cytokines are secreted proteins that act as local immunological mediators. Increased seminal cytokine concentrations are associated with fertility problems. The purpose of the present study was to investigate the presence of IL-2alpha, and IL-2beta receptors on fresh and isolated sperm by flow cytometry and transmission electron microscopy. Twenty sperm samples from oligospermic men were incubated with CD25, a mouse monoclonal antibody specific for IL-2alpha-chain receptor, and CD122, a mouse monoclonal antibody specific for IL-2beta-chain receptor. The strong initial fluorescence intensity and, subsequently, a labeling index yielded by CD25 and CD122 decreased in sperm centrifuged on a Percoll gradient (p < .05). The expression of CD25 and CD122 correlated negatively with fresh sperm concentration, but in sperm centrifuged on a Percoll gradient there was no correlation. Labeling with CD25 and CD122 antibody was evident on the head and the middle piece in fresh sperm, while in sperm centrifuged on a Percoll gradient a weak labeling was observed only on the principal piece. The authors have identified and localized cytokine receptors on human sperm for the first time. Cytokine receptors may be involved in the regulation of pathophysiological events in sperm cell functions and male infertility. The exact pathway involved in modulation of these receptors requires further investigation. These results contribute to the understanding of cytokine-sperm relationships.

Flow Cytometry↗
PubMedDate not supplied

Membrane status and in vitro capacitation of porcine sperm preserved in long-term extender at 16 degrees C.

Preservation of porcine semen in long-term extenders at 15-18 degrees C for more than 5 days results in decreased farrowing rates and reduced litter size after artificial insemination, despite the high progressive motility rates of sperm. To improve this preservation system it is necessary to understand sperm physiology under storage conditions. The purpose of this study was to determine the effect of storing diluted porcine semen (during 0, 2, 4, 6, and 8 days) on the sperm membranes status and the ability of sperm to respond to in vitro capacitation treatment. Ten semen samples from 5 adult boars were analyzed. Two aliquots were obtained from the sperm-rich fraction: one was used to assess fresh semen and the other was diluted in Reading extender and stored at 16 degrees C. Both semen samples were stained with chlortetracycline to assess the status of sperm membranes and with Hoechst 33258 to determine viability. Semen storage for 4-8 days increased the proportion of prematurely capacitated sperm. After 4 days of storage, in vitro capacitation treatment did not increase the percentage of capacitated sperm, but increased the percentage of acrosome reacted sperm. This phenomenon could explain the reduced fertilizing ability of porcine semen stored at 16 degrees C for over 4 days, in spite of the acceptable sperm viability and progressive motility.

Animals↗
PubMedDate not supplied

Ultrastructural morphology and morphometry of epididymal sperm in the volcano rabbit (Romerolagus diazi).

Sperm characteristics of Romerolagus diazi, an endemic endangered rabbit from Mexico's Higlands, are poorly known. Knowledge of gamete characteristics are urged for any conservation-oriented strategy and morphometry-based taxonomical database. Sperm lagomorph comparisons have been made at light microscopy resolution. Our goal was to analyze the ultrastructure of the R. diazi male gamete. Two wild animals were kept in captivity and the epididymus were obtained. Fixed gametes show a characteristic spatula-like morphology with a dilated forefront. The nucleus has an arrow head morphology lightly thicker at the base. Tail ultrastructure is similar to that of laboratory rabbits with an end piece thicker than that of human sperm. Morphometry data could be used for construction of a male gamete data base for further studies.

Animals↗
PubMedDate not supplied

Individual cryopreservation with dimethyl sulfoxide and polyvinylpyrrolidone of ejaculates and pooled semen of three avian species.

Artificial insemination (AI) has been used for avian reproduction due to the discovery of cryoprotectants extending its usefulness both in production of domestic fowl and conservation of wild species. The goal of this study was to assess the effect on domestic and wild fowl pooled semen and individual ejaculate cryopreservation with dimethyl sulfoxide (DMSO) and polyvinylpyrrolidone (PVP). Twenty ejaculates and twenty samples of pooled semen of roosters, pheasants and hawks were frozen in media containing DMSO or PVP. DMSO and PVP cryopreservation are equally effective both for ejaculates and pooled semen. Even PVP is a good alternative since no significant difference was found when compared to DMSO. The fertilizing capacity of fresh and cryopreserved pooled semen was analyzed through AI of hens and female pheasants. Similar fertility rates using DMSO, PVP or frozen-thawed samples demonstrated that reproduction is possible through the use of cryopreserved semen. In the case of female pheasants, the same values were obtained with both cryopreserved and fresh semen.

Animals↗
PubMedDate not supplied

Lectin-binding sites on human sperm during acrosome reaction: modifications judged by electron microscopy/flow cytometry.

Biochemical surface modifications occur during the capacitation and acrosome reaction of human sperm and among those, variations in the expression of carbohydrates moieties. A sequential study was performed with electronic microscopy and flow cytometry techniques, where the binding of 4 lectins was assessed on normal human sperm samples during in vitro induction of the acrosome reaction with calcium ionophore A-23187. Triticum vulgaris agglutinin (WGA) was shown to bind strongly the whole surface of sperm before induction of the acrosome reaction, and in lesser amounts after incubation with calcium ionophore. Arachis hypogea agglutinin (PNA) and mostly Concanavalia ensiformis agglutinin (Con-A) and Ulex europaeus agglutinin (UEA-1) binding evolved in an opposite pattern with an increase of the labeling parallel to that of GB24 antibody binding. Electron microscopy showed that the fluorescence patterns observed correlated with increased access to the inner membrane of the acrosome. This was significant 60 min after the induction of acrosome reaction. Lectin binding could be a useful tool to examine the ability of sperm samples to undergo the acrosome reaction.

Acrosome↗