The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Navarrete Gomez, Patricia Alejandra - One of the best experts on this subject based on the ideXlab platform.
-
ACCION MODULADORA DEL OVIDUCTO Y SUS SECRECIONES SOBRE EL EFECTO DE LA ARACNOTOXINA DE Latrodectus mactans EN LA FUNCION ESPERMÁTICA
2014Co-Authors: Navarrete Gomez, Patricia AlejandraAbstract:La aracnotoxina (Atx) de Latrodectus mactans (L. mactans) induce cambios en la función espermática que podrían utilizarse con fines anticonceptivos. Estudios preliminares en espermatozoides incubados con la Atx de L. mactans de Chile, desarrollados por nuestro laboratorio, indican que la Atx altera el pH intracelular, factor biológico fundamental en la regulación de la motilidad espermática, la capacitación y la reacción acrosómica. Estos procesos, requieren de niveles bajos de especies reactivas de oxígeno (ROS) y su efecto modulador está asociado al oviducto y sus secreciones, ya que su incremento puede inducir daño al ADN y las membranas espermáticas. Para evaluar este efecto sobre la función espermática, es indispensable conocer y entender la fisiología del espermatozoide en condiciones normales, en contacto con el oviducto y sus secreciones y con la Atx. En esta línea, el objetivo de esta tesis doctoral se centra en el estudio del efecto modulador del oviducto y sus secreciones sobre la acción de la Atx de L. mactans en la función espermática. Para ello, espermatozoides de bovino fueron incubados con Atx y/o caincubados con explantes y secreciones oviductales, tanto ampulares como istmales, para luego determinar el comportamiento de los canales de calcio, la reacción acrosómica, la integridad del ADN y la producción de ROS tanto intracelulares como extracelulares. Los resultados obtenidos indican que los explantes de oviducto, asi como sus secreciones, no parecen modular el efecto de la Atx de L. mactans sobe la función espermática, sino que, por el contrario, la Atx de L. mactans aún en presencia de explantes de oviducto y sus secreciones altera la integridad del ADN espermático, suprime la producción de ROS y disminuye la reacción acrosómica independientemente del tiempo de incubación y de la composición del medio de incubación. Además, el microambiente del oviducto induce fragmentación del ADN espermático y aumenta la producción de ROS en los espermatozoides, independientemente del tiempo de incubación. Asimismo, los niveles de ROS producidos inducen fragmentación del ADN espermático, pero este fenómeno sólo se produce tras períodos de incubación relativamente cortos. Finalmente, la Atx tiene un efecto deletéreo sobre la función espermática que podría utilizarse con fines anticonceptivos
-
ACCION MODULADORA DEL OVIDUCTO Y SUS SECRECIONES SOBRE EL EFECTO DE LA ARACNOTOXINA DE Latrodectus mactans EN LA FUNCION ESPERMATICA
2011Co-Authors: Navarrete Gomez, Patricia AlejandraAbstract:La aracnotoxina (Atx) de Latrodectus mactans (L. mactans) induce cambios en la función espermática que podrían utilizarse con fines anticonceptivos. Estudios preliminares en espermatozoides incubados con la Atx de L. mactans de Chile, desarrollados por nuestro laboratorio, indican que la Atx altera el pH intracelular, factor biológico fundamental en la regulación de la motilidad espermática, la capacitación y la reacción acrosómica. Estos procesos, requieren de niveles bajos de especies reactivas de oxígeno (ROS) y su efecto modulador está asociado al oviducto y sus secreciones, ya que su incremento puede inducir daño al ADN y las membranas espermáticas. Para evaluar este efecto sobre la función espermática, es indispensable conocer y entender la fisiología del espermatozoide en condiciones normales, en contacto con el oviducto y sus secreciones y con la Atx. En esta línea, el objetivo de esta tesis doctoral se centra en el estudio del efecto modulador del oviducto y sus secreciones sobre la acción de la Atx de L. mactans en la función espermática. Para ello, espermatozoides de bovino fueron incubados con Atx y/o caincubados con explantes y secreciones oviductales, tanto ampulares como istmales, para luego determinar el comportamiento de los canales de calcio, la reacción acrosómica, la integridad del ADN y la producción de ROS tanto intracelulares como extracelulares. Los resultados obtenidos indican que los explantes de oviducto, asi como sus secreciones, no parecen modular el efecto de la Atx de L. mactans sobe la función espermática, sino que, por el contrario, la Atx de L. mactans aún en presencia de explantes de oviducto y sus secreciones altera la integridad del ADN espermático, suprime la producción de ROS y disminuye la reacción acrosómica independientemente del tiempo de incubación y de la composición del medio de incubación. Además, el microambiente del oviducto induce fragmentación del ADN espermático y aumenta la producción de ROS en los espermatozoides, independientemente del tiempo de incubación. Asimismo, los niveles de ROS producidos inducen fragmentación del ADN espermático, pero este fenómeno sólo se produce tras períodos de incubación relativamente cortos. Finalmente, la Atx tiene un efecto deletéreo sobre la función espermática que podría utilizarse con fines anticonceptivos.La aracnotoxina (Atx) de Latrodectus mactans (L. mactans) induce cambios en la función espermática que podrían utilizarse con fines anticonceptivos.Estudios preliminares en espermatozoides incubados con la Atx de L. mactans de Chile, desarrollados por nu
Fernando Romero - One of the best experts on this subject based on the ideXlab platform.
-
effect of aracnotoxin from Latrodectus mactans on bovine sperm function modulatory action of bovine oviduct cells and their secretions
Andrologia, 2012Co-Authors: P N Gomez, Jorge Parodi, Fernando Romero, Juan G Alvarez, R SanchezAbstract:Summary Latrodectus mactans’ aracnotoxin (Atx) induces changes in sperm function that could be used as a co-adjuvant in male contraceptive barrier methods. This effect includes the suppression of intracellular reactive oxygen species (ROS), an event necessary for capacitation, chemotaxis and acrosome reaction (AR). The sperm that are not trapped by the barrier method can reach the oviduct before fertilisation and be exposed to the secretions of the oviducts. This study evaluated the effect of bovine tubal explants (TU) and conditioned media (CM) from the ampullar and isthmal regions on spermatozoa exposed to Atx. Thawed bovine sperm were incubated with Atx, TU and CM from the ampullar and isthmal regions for 4 h and then DNA integrity, intracellular ROS and lysophosphatidylcholine-induced AR were determined. Spermatozoa exposed to Atx and co-incubated with TU and CM for 4 h produced an increase in sperm DNA damage, a decrease in ROS production and a decrease in %AR, compared with the control. A similar result was obtained from the co-incubation of spermatozoa with Atx. In conclusion, the effect of Atx is not modified by tubal cells or their secretions and this opens the door to future studies to evaluate the application of synthetic peptides obtained from Atx as a co-adjuvant of contraceptive barrier methods.
-
research communication tetraethylammonium sensitive k current in the bovine spermatozoa and its blocking by the venom of the chilean Latrodectus mactans
2010Co-Authors: Jorge Parodi, Patricia Navarrete, Marcelo Marconi, Fernando RomeroAbstract:The morphology and size of spermatozoa hinder the study of the functional properties of the spermatozoa plasma membrane. However, some studies have revealed the presence of a number of ion channels in this cell. We set out to measure the endogenous currents and to study the effect of the venom of the Chilean black widow spider (Latrodectus mactans). By patch-clamping bovine spermatozoa our results indicate the presence of an outwardly rectifying current, sensitive to changes in K + concentration (30–140 mM) and to tetraethylammonium (TEA, 10–100 mM). The application of the venom (7.5 g/ml) blocks these K+ currents and then alters the passive properties of the plasma membrane. This leads to the entry of Ca ++ ,r ef lected by ac hange in basal fluorescent units (57 2a t 35710 FAU). The Ca ++ influx follows a reduction in the membrane conductance (control 2272; venom 1071 pS), as calcium channels open in accord with voltage dependence.
-
some effects of the venom of the chilean spider Latrodectus mactans on endogenous ion currents of xenopus laevis oocytes
Biochemical and Biophysical Research Communications, 2008Co-Authors: Jorge Parodi, Fernando Romero, Ricardo Miledi, Ataulfo MartineztorresAbstract:Abstract A study was made of the effects of the venom of the Chilean spider Latrodectus mactans on endogenous ion-currents of Xenopus laevis oocytes. 1 μg/ml of the venom made the resting plasma membrane potential more negative in cells voltage-clamped at −60 mV. The effect was potentially due to the closure of one or several conductances that were investigated further. Thus, we determined the effects of the venom on the following endogenous ionic-currents: (a) voltage-activated potassium currents, (b) voltage-activated chloride-currents, and (c) calcium-dependent chloride-currents (Tout). The results suggest that the venom exerts its action mainly on a transient outward potassium-current that is probably mediated by a Kv channel homologous to shaker. Consistent with the electrophysiological evidence we detected the expression of the mRNA coding for xKv1.1 in the oocytes.
-
Synaptic effects of low molecular weight components from Chilean Black Widow spider venom.
Neurotoxicology, 2008Co-Authors: Jorge Parodi, Fernando RomeroAbstract:Abstract α-Latrotoxin is the principal component of the venom from the euroasiatic Black Widow spider and has been studied for its pharmacological use as a synaptic modulator. Interestingly, smaller molecular weight fractions have been found to be associated with this toxin, but their cellular actions have not been studied in detail. The venom from the Chilean Black Widow spider (Latrodectus mactans) does not produce α-latrotoxin, however it does contain several small polypeptides. We have recently demonstrated cellular effects of these peptides at the synaptic level using whole-cell patch clamp techniques. Purified venom from the glands of L. mactans was studied in 12 DIV rat hippocampal neuronal cultures. Venom at a concentration of 10 nM was able to decrease neuronal conductance thereby increasing membrane resistance. This effect on the passive properties of the neurons induced a change in action potential kinetics simulating the action of classic potassium channel blockers. These changes produced an increase in spontaneous synaptic activity in rat hippocampal cultures in the presence of the venom in a concentration- and time-dependent manner. These results indicate that venom from Chilean spider L. mactans is capable of increasing cell membrane resistance, prolonging the action potential and generating an increase in synaptic activity demonstrating an interesting pharmacological effect of these low molecular weight fragments.
-
venom of Latrodectus mactans from chile araneae theridiidae effect on smooth muscle
Revista De Biologia Tropical, 2003Co-Authors: Fernando Romero, Elena Altieri, Mauricio Urrutia, Jorge JaraAbstract:The venoms of Latrodectus sp. have been reported to induce contraction probably mediated by adrenergic and cholinergic transmitters. We have demonstrated that the venom of Chilean Latrodectus mactans contains neurotoxins that induce a contraction partially independent of transmitters release. Transmembrane mobility of Na+ and Ca2+ ions and more specifically, the increase of cytoplasmic calcium concentration are responsible for tonic contraction in smooth muscle. Calcium may enter the cell by several ways, such as the voltage-dependent Ca2+ L-type channels and the Na+/Ca2+ exchanger. This study aimed to examine the participation of this exchanger in the tonic contraction of smooth muscle in vas deferent of rat induced by the venom of the Chilean spider L. mactans. Blockers of Na+ channels (amiloride) and Ca2+ L-type channels (nifedipine), and a stimulator of the exchanger (modified Tyrode, Na+ 80 mM) were used. Simultaneously, variations of the cytoplasmic concentration of Ca2+ were registered by microfluorimetry (Fura-2 indicator) in the presence of nifedipine. In presence of amiloride, dose-dependent inhibition of venom-induced contraction was observed, suggesting the participation of voltage-dependent Ca2+ L-type channels. The contraction was only partially inhibited by nifedipine and the Ca2+ cytoplasmic concentration increased, as assessed by the microfluorimetric registration. Finally, the venom-induced contraction increased in the presence of modified Tyrode, probably due to the action of the Na+/Ca2+ exchanger. Taken together, our results support the idea that the Na+/Ca2+ exchanger is active and may be, at least in part, responsible for the contraction induced by the venom of Chilean L. mactans.
Richard F Clark - One of the best experts on this subject based on the ideXlab platform.
-
the treatment of black widow spider envenomation with antivenin Latrodectus mactans a case series
The Permanente Journal, 2011Co-Authors: G P Daubert, Richard F ClarkAbstract:Black widow spiders (Latrodectus mactans) are found throughout the US. Though bites are relatively uncommon, they pose a significant health problem with over 2500 reported to American poison control centers annually. Black widow spider bites cause a characteristic envenomation syndrome consisting of severe pain, muscle cramping, abdominal pain, and back pain. The significant pain associated with envenomation is often refractory to traditional analgesics. Antivenom (Antivenin Latrodectus mactans) is available and effective, but is often withheld because of a fear of acute hypersensitivity reactions. We report four cases of symptomatic black widow spider envenomation. One of the reported cases was managed without antivenom, and, in contrast, three were treated successfully with Antivenin Latrodectus mactans. We believe that these cases demonstrate safe and effective use of black widow antivenom. This article presents the rationale for use of antivenom in these cases, and a nonsystematic review of the pertinent literature.
-
the safety and efficacy of antivenin Latrodectus mactans
Clinical Toxicology, 2001Co-Authors: Richard F ClarkAbstract:Latrodectus species of spiders are ubiquitous throughout the world. The United States is home to at least five varieties, and the North American native Latrodectus mactans can now be found around t...
Silva Correa Carmen - One of the best experts on this subject based on the ideXlab platform.
-
EFECTO DEL VENENO DE Latrodectus mactans EN LOS NIVELES PLASMÁTICOS DE ÓXIDO NÍTRICO Y EN EL COMPORTAMIENTO SEXUAL EN Oryctolagus cunniculus
UNIVERSIDAD NACIONAL DE TRUJILLO, 2014Co-Authors: Huari Marín Gloria, Jiménez Rodríguez Yhen, Julca Majo Alan, Lpoez Díaz Sandra, Llapo Miñano Andy, Mendoza Sicche Juan, Luis Reyna Martín, Becerra Urquizo Andrea, Guzmán Ruiz Liliana, Silva Correa CarmenAbstract:Objetivo: El objetivo del presente trabajo fue evaluar el efecto del veneno de Latrodectus mactans en los niveles plasmáticos de óxido nítrico y el comportamiento sexual de Oryctolagus cunniculus. Material y método: Se capturaron 10 especímenes de Latrodectus mactans en las inmediaciones del campus de la Universidad Nacional de Trujillo en lugares secos, abrigados y oscuros. Se adquirieron 7 especímenes machos y 7 hembras de Oryctolagus cunniculus a los que se inyectó 0.1 mL de veneno de araña. Se determinaron los niveles de óxido nítrico (NO) indirectamente por la conversión en nitritos (NO2-) y nitratos (NO3-) que son los principales productos de degradación del NO, por el método de Método de Griess. Se evaluó el comportamiento sexual teniendo en cuenta los siguientes parámetros: frecuencia de monta, frecuencia de intromisiones, latencia de monta, latencia de intromisiones y latencia post eyaculatoria. Resultados: Se observó que los niveles de NO aumentaron en promedio a 7.75µmol /ml con la administración de 0.1 ml del homogenizado de veneno de Latrodectus mactans (p < 0.05) comparados con la administración de 0.1 mL de Solución Salina Fisiológica (grupo blanco) que aumentó a 4.06µmol /ml en promedio (p < 0.05). En el comportamiento sexual se observó un aumento en la frecuencia de monta, frecuencia de intromisiones y disminución en la latencia de intromisiones y latencia post eyaculatoria (p < 0.05). Conclusiones: El veneno de Latrodectus mactans eleva en forma significativa los niveles plasmáticos de óxido nítrico en Oryctolagus cunniculus, además estimula el comportamiento sexual de dichos especímenes. Palabras clave: Latrodectus mactans, Óxido nítrico, comportamiento sexual.
-
efecto del veneno de Latrodectus mactans en los niveles plasmaticos de oxido nitrico y en el comportamiento sexual en oryctolagus cunniculus effect of Latrodectus mactans venom in plasma nitric oxide levels and sexual behavior in oryctolagus cunniculus
2014Co-Authors: Huari Marín Gloria, Jiménez Rodríguez Yhen, Julca Majo Alan, Mendoza Sicche Juan, Luis Reyna Martín, Lopez Diaz Sandra, Becerra Urquiza Andrea, Guzman Ruiz, Silva Correa CarmenAbstract:Objective: The aim of this study was to evaluate the effect of Latrodectus mactans venom in plasma levels of nitric oxide and the sexual behavior of Oryctolagus cunniculus. Methods: 10 specimens of L. mactans were caught near the campus of the National University of Trujillo from dry, warm and dark places. Seven male and seven female specimens of Oryctolagus cunniculus were purchased. The levels of nitric oxide (NO) was determined indirectly (Griess method) by conversion to nitrite (NO2 - ) and nitrate (NO3 - ) which are the main products of degradation of NO. Sexual behavior was evaluated through of parameters as mount frequency, intromission frequency, mount latency, intromission latency and post-ejaculatory latency. Results: Nitric oxide levels increased an average of 7.75 µmol / ml with administration of 0.1 ml of homogenized venom from Latrodectus mactans (p < 0.05) compared with administration of 0.1 mL of physiologic sodium chloride (white group) in which levels of nitric oxide increased only at 4.06 µmol/ml on average (p<
Leocadia V. Paliulis - One of the best experts on this subject based on the ideXlab platform.
-
Co-segregation of sex chromosomes in the male black widow spider Latrodectus mactans (Araneae, Theridiidae)
Chromosoma, 2017Co-Authors: Jeffrey G. Ault, Kristen D. Felt, Ryan N. Doan, Alexander O. Nedo, Cassondra A. Ellison, Leocadia V. PaliulisAbstract:During meiosis I, homologous chromosomes join together to form bivalents. Through trial and error, bivalents achieve stable bipolar orientations (attachments) on the spindle that eventually allow the segregation of homologous chromosomes to opposite poles. Bipolar orientations are stable through tension generated by poleward forces to opposite poles. Unipolar orientations lack tension and are stereotypically not stable. The behavior of sex chromosomes during meiosis I in the male black widow spider Latrodectus mactans (Araneae, Theridiidae) challenges the principles governing such a scenario. We found that male L. mactans has two distinct X chromosomes, X_1 and X_2. The X chromosomes join together to form a connection that is present in prometaphase I but is lost during metaphase I, before the autosomes disjoin at anaphase I. We found that both X chromosomes form stable unipolar orientations to the same pole that assure their co-segregation at anaphase I. Using micromanipulation, immunofluorescence microscopy, and electron microscopy, we studied this unusual chromosome behavior to explain how it may fit the current dogma of chromosome distribution during cell division.