835 research outputs found
Treatment with zinc, d-aspartate, and coenzyme Q10 protects bull sperm against damage and improves their ability to support embryo development.
No full textReactive oxygen species (ROS) are physiologically generated during mitochondrial respiration and are involved in several signaling mechanisms. However, under pathological conditions, the concentration of ROS may exceed the antioxidant scavenging systems and subsequently lead to cell damage. High ROS levels have been proven to be detrimental to spermatozoa and furthermore compromise sperm function through lipid peroxidation, protein damage, and DNA strand breakage. Although the oral administration of antioxidants has been demonstrated to improve the semen quality in subfertile men, it is still a matter of debate if it can positively influence fertilization outcome and embryo developmental competence. Studies carried out in suitable animal models could resolve these fundamental questions. Hence, the main aims of the present study were to evaluate: (1) the effects of zinc, d-aspartate, and coenzyme Q10, included in the dietary supplement Genadis (Merck Serono), on bull sperm motility and DNA fragmentation; and (2) whether treated spermatozoa have a superior competence in fertilization and in supporting the development of healthy embryos. Our data indicate that this treatment prevents the loss of sperm motility and the rise in sperm DNA fragmentation over time. Moreover, blastocyst rate was found to be significantly higher in oocytes fertilized by treated spermatozoa, and these blastocysts harbored a significantly lower percentage of apoptotic cells
Analytical Modelling of Fluid-Structure Interaction: On Developing Equations to Understanding Rizos' Experiment (2016)
No full textThe activities of humans in the marine environment are on a steady rise; this trend follows the exposure of offshore structures and vessels to harsh environmental conditions. On the other hand, there is continuous demand for lighter, faster and more efficient vessels. Technological advancement in composite materials and better design methods invariably leads to more sophisticated computational tools. In these tools, the inherent flexibility of the structure is involved in the calculation of itsloading and response – introducing the aspect of fluid-structure interaction. However, more than fluid-structure interaction, hydroelasticity which is a subset of fluid-structure interaction allows for deformation of the structures due to fluid. Current industry practice neglects these deformations and all structures are designed as rigid bodies. These practices lead to overestimation of the frequency which translates to the mass and how stiff the structure is. Design based on hydroelasticityallows for knowing the true behaviour of the structure; thus, a coupling of fluid and structure yields a true appreciation of these designs. The objective of this study is to formulate and solve analytically the coupling phenomenon behind fluid-structure interaction. An experiment designed by Lampros Rizos in 2016 which modelled fluid-structure interaction consisted of a set-up with a cylinder immersed in a larger cylindrical tank. The immersed cylinder having a flexible circular membrane (structure) located at its bottom. The cylinders were filled with non-viscous liquid and exhibited free surface. The designed experiment was decoupled and a systematic build up in understanding the dynamics of all components – structure and fluid were solved. Firstly, the dynamics of the structure when dry (In vacuo) was idealized in 2-D and 3-D. Secondly, the system was coupled and solvedin 2-D and 3-D when structure is located at the top and bottom of a single cylinder individually. The use of a series solution: Fourier-Cosine and Fourier-Bessel series solutions were used for 2-D and 3-D cases respectively. Along with these series solutions, the fluid governing equations were employed to solve for the coupled frequencies. Lastly, the entire submerged structure was analysed and solved. The hydroelastic or coupled frequencies and vibration patterns are determined for lower angular and radial modes for which the influences of various parameters are investigated. A trend was observed – that for lower modes, the hydroelastic frequencies are lower than individual membrane natural frequencies at low frequencies. At higher frequencies, the coupling effects are larger making the coupled frequency higher than uncoupled frequencies. There is a strong relationship between the tension of the membrane and the hydroelastic frequencies. An increase in the tension causes an increase in the hydroelastic frequencies. Also, the hydroelastic frequencies increase as the fluid depth increases. More so, the increase in fluid depth tends to converge towards the uncoupled fluid free-surface frequency. The comparison of the analytical solution with experimental and numerical solutions does not match perfectly and thus, further works to improve this study are recommended.Offshore and Dredging Engineerin
Author Correction: The geology and evolution of the Near-Earth binary asteroid system (65803) Didymos
No full textBarnouin, Olivier S. et al.-- Full list of authors: Barnouin, Olivier; Ballouz, Ronald-Louis; Marchi, Simone; Vincent, Jean-Baptiste; Agrusa, Harrison; Zhang, Yun; Ernst, Carolyn M.; Pajola, Maurizio; Tusberti, Filippo; Lucchetti, Alice; Daly, R. Terik; Palmer, Eric; Walsh, Kevin J.; Michel, Patrick; Sunshine, Jessica M.; Rizos, Juan L.; Farnham, Tony L.; Richardson, Derek C.; Parro, Laura M.; Murdoch, Naomi; Robin, Colas Q.; Hirabayashi, Masatoshi; Kahout, Tomas; Asphaug, Erik; Raducan, Sabina D.; Jutzi, Martin; Ferrari, Fabio; Hasselmann, Pedro Henrique Aragao; CampoBagatin, Adriano; Chabot, Nancy L.; Li, Jian-Yang; Cheng, Andrew F.; Nolan, Michael C.; Stickle, Angela M.; Karatekin, Ozgur; Dotto, Elisabetta; Della Corte, Vincenzo; Mazzotta Epifani, Elena; Rossi, Alessandro; Gai, Igor; Deshapriya, Jasinghege Don Prasanna; Bertini, Ivano; Zinzi, Angelo; Trigo-Rodriguez, Josep M.; Beccarelli, Joel; Ivanovski, Stavro Lambrov; Brucato, John Robert; Poggiali, Giovanni; Zanotti, Giovanni; Amoroso, Marilena; Capannolo, Andrea; Cremonese, Gabriele; Dall'Ora, Massimo; Ieva, Simone; Impresario, Gabriele; Lavagn, Michèle; Modenini, Dario; Palumbo, Pasquale; Perna, Davide; Pirrotta, Simone; Tortora, Paolo; Zannoni, Marco; Rivkin, Andrew S.In this article the funding from the Spanish project PID2021-128062NB-I00 funded by MCIN/AEI
was omitted. The original article has been corrected.Peer reviewe
Numerical Simulation of the Interaction of A Membrane with Water with A Free Surface: Simulation of An Experiment by L. Rizos
No full textIn order to collect validation data for the study of the mechanism of fluid-structure interaction (FSI), an lab experiment was conducted by L. Rizos in the towing tank, 3ME,TUDelft in 2016. The concept of the experiment is shown in the figure 1. A cylindrical container is partially filled with water. A small cylindrical oscillator with flexible bottom is placed in the container. The oscillator is driven harmonically by a motor. During the experiment, the deflection of the flexible bottom, the motion of the free surface and the driven force were monitored and recorded. The figure 2 is the photo of the experiment. In order to better understand Rizos’ experiment, a series of researches are conducted in the Section Ship Hydromechanics, which includes analytical simulation and several numerical simulations with different methods. A linear algorithm is developed in this thesis, which applies implicit, monolithic (solving the fluid domain and structure domain simultaneously) and one-step (without iteration) methods. The model of the numerical simulation is shown in the figure 3, a small cylinder with flexible bottom is placed in the big cylindrical container. The two cylinders are partially filled with water and the still water levels are the same. The inner cylinder does not moves up and down as a whole. The oscillation of the whole system is the result of the initial wave elevation in the fluid domain and/or the initial deflection in the structure domain. The result of the numerical simulation is shown in the figure 4. The effect of added mass for a structure submerged in water results in that smaller eigen frequency of the structural vibration. The structure interacts with the ambient fluid, especially the free surface. For a pre-defined initial condition, the influence of the free surface results in the mode dispersion. The numerical periods of this FSI system agrees with the analytical periods. Significant numerical dissipation exists in the 1st order time integration techniques. Thus, the second order implicit Adam Moulton method, i.e., the trapezoidal rule, is implemented to improve the algorithm. in this way, the numerical dissipation is decreased drastically (5% less dissipation after 10 periods) without increasing the computational costs.Offshore and Dredging Engineerin
University of Newcastle upon Tyne, UK. Joel has assisted
No full textin the development of the Locata receiver and testing of the Locata technology. Other current research interests include pseudolites, GPS receiver firmware customisation and high precision kinematic GPS positioning. Chris Rizos is a Professor and Head of the School o
Contribution of the female reproductive tract to low fertility in postpartum lactating dairy cows
No full textInfertility in dairy cattle is a multifactorial problem that may be linked to follicle development and the quality of the ovulated oocyte, to sperm transport and fertilization, to the reproductive tract environment, or to a combination of these factors. Using a state-of-the-art endoscopic embryo transfer technique, the aim of this study was to compare the ability of the reproductive tract of postpartum dairy cows and nulliparous heifers to support the development of early embryos to the blastocyst stage. Bovine embryos of 2 to 4 cells (n=1,800) were produced by in vitro maturation and fertilization of oocytes derived from the ovaries of slaughtered cattle. The estrus cycles of nulliparous Holstein heifers (n=10) and postpartum Holstein cows (n=8, approximately 60 d postpartum) were synchronized using an 8-d controlled internal drug release device coupled with prostaglandin injection. On d 2, one hundred 2- to 4-cell embryos were endoscopically transferred to the oviduct ipsilateral to the corpus luteum. Five days later, on d 7, the oviduct and uterus were flushed nonsurgically to recover the embryos. The number of embryos developing to the blastocyst stage was recorded immediately at recovery and following overnight culture in vitro. A representative number of blastocysts from heifers and cows were stained to assess cell number. Progesterone concentrations were lower in cows than in heifers on d 5, 6, and 7 (d 7=2.39±0.33 vs. 5.34±0.77. ng/mL, respectively). More embryos were recovered from heifers than cows (79.0±7.0 vs. 57.2±11.4%). Of the embryos recovered, 33.9±3.6% had developed to the blastocyst stage in the heifer oviduct compared with 18.3±7.9% in the postpartum cow oviduct. There was no evidence of a difference in blastocyst quality as evidenced by total cell number in the blastocysts (71.2±5.7 vs. 67.0±5.3, respectively). In conclusion, the reproductive tract of the postpartum lactating dairy cow may be less capable of supporting early embryo development than that of the nonlactating heifer, and this may contribute to the lower conception rates observed in such animals. © 2010 American Dairy Science Association
Bovine embryo-oviduct interaction in vitro reveals an early cross talk mediated by BMP signaling
No full textSignaling components of bone morphogenetic proteins (BMPs) are expressed in an anatomically and temporally regulated fashion in bovine oviduct. However, a local response of this signaling to the presence of the embryo has yet to be elucidated. The aim of the present study was to evaluate if early embryo-oviduct interaction induces changes in the gene expression of BMP signaling components. For this purpose, we used an in vitro co-culture system to investigate the local interaction between bovine oviductal epithelial cells (BOEC) from the isthmus region with early embryos during two developmental periods: before (from the 2-cell to 8-cell stage) or during (from the 8-cell to 16-cell stage) the main phase of embryonic genome activation (EGA). Exposure to embryos, irrespective of the period, significantly reduced the relative abundance of BMPR1B, BMPR2, SMAD1, SMAD6 and ID2 mRNAs in BOEC. In contrast, embryos that interacted with BOEC before EGA showed a significant increase in the relative abundance of SMAD1 mRNA at the 8-cell stage compared to embryos cultured without BOEC. Moreover, embryos at the 16-cell stage that interacted with BOEC during EGA showed a significant increase in BMPR1B, BMPR2 and ID2 mRNA. These results demonstrate that embryo-oviduct interaction in vitro induces specific changes in the transcriptional levels of BMP signaling, causing a bidirectional response that reduces the expression levels of this signaling in the oviductal cells while increases them in the early embryo. This suggests that BMP signaling pathway could be involved in an early cross talk between the bovine embryo and the oviduct during the first stages of development.Fil: Garcia, Elina Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria; EspañaFil: Hamdi, Meriem. Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria; EspañaFil: Barrera, Antonio Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria; EspañaFil: Sánchez Calabuig, María Jesús. Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria; EspañaFil: Gutiérrez Adan, Alfonso. Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria; EspañaFil: Rizos, Dimitrios. Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria; Españ
Treatment with zinc, D-aspartate, and coenzyme Q10 protects bull sperm against damage and improves their ability to support embryo development
No full textReactive oxygen species (ROS) are physiologically generated during mitochondrial respiration and are involved in several signaling mechanisms. However, under pathological conditions, the concentration of ROS may exceed the antioxidant scavenging systems and subsequently lead to cell damage. High ROS levels have been proven to be detrimental to spermatozoa and furthermore compromise sperm function through lipid peroxidation, protein damage, and DNA strand breakage. Although the oral administration of antioxidants has been demonstrated to improve the semen quality in subfertile men, it is still a matter of debate if it can positively influence fertilization outcome and embryo developmental competence. Studies carried out in suitable animal models could resolve these fundamental questions. Hence, the main aims of the present study were to evaluate (1) the effects of zinc, d-aspartate, and coenzyme Q10, included in the dietary supplement Genadis (Merck Serono), on bull sperm motility and DNA fragmentation; and (2) whether treated spermatozoa have a superior competence in fertilization and in supporting the development of healthy embryos. Our data indicate that this treatment prevents the loss of sperm motility and the rise in sperm DNA fragmentation over time. Moreover, blastocyst rate was found to be significantly higher in oocytes fertilized by treated spermatozoa, and these blastocysts harbored a significantly lower percentage of apoptotic cells. © 2014 Elsevier Inc
The association between metabolic parameters and oocyte quality early and late postpartum in Holstein dairy cows
No full textThe objective of this was to study the association between metabolic parameters and oocyte quality in postpartum lactating dairy cows as assessed by oocyte morphology and development after fertilization and culture in vitro. Holstein-Friesian spring-calving cows were used (n = 16, parity 3.0±0.36, weight at calving 611±16.2. kg, previous 305-d milk yield 6,454.0±276.4. kg). Bodyweight (BW) and body condition score were recorded at approximately 2 wk before expected calving date, at calving, and then weekly until the end of the experiment (approximately 80 d postpartum). Blood plasma samples were collected weekly, starting 2 wk before the expected calving date and continuing until the end of the experiment and were analyzed for nonesterified fatty acids (NEFA), β-hydroxybutyrate (BHBA), insulin, insulin-like growth factor-I, and glucose. Transvaginal oocyte recovery was carried out twice weekly on each cow for a period of approximately 12 wk starting 14 d after calving until approximately 80 d postpartum. A linear decrease in BW was observed from calving (d 0) to d 28, after which it remained stable. Body condition score decreased from 14 d precalving, reaching a nadir at approximately d 35 to 42, after which it increased to the end of the period. Nonesterified fatty acid concentrations were significantly elevated from the week before calving until d 42 postcalving, whereas BHBA concentration was significantly elevated from calving to d 49 postcalving. Insulin-like growth factor-I concentration dramatically decreased from d -14 to a nadir on d 7. A significant increase in glucose concentration occurred from d -7 to d 0, followed by a precipitous decrease to d 7. Based on the metabolic profiles (particularly NEFA and BHBA concentrations), data from d 0 to 42 postpartum (period 1) were compared with corresponding data from d 42 to 80 (period 2). Apart from body condition score, all of the physiological parameters measured (milk yield, BW, and blood metabolites) differed significantly between the 2 periods. In particular, insulin-like growth factor-I, insulin, and glucose concentrations were higher post-d 42, whereas BHBA and NEFA were lower compared with pre-d 42 postpartum. The number of oocytes recovered per session and oocyte quality grade did not differ between periods. Positive associations of follicles aspirated and insulin, BHBA, and NEFA were detected. The number of oocytes recovered was positively associated with milk yield, BW, and glucose and NEFA concentrations. The number of cleaved oocytes was positively associated with BW and NEFA concentration. In conclusion, the data do not provide evidence of an effect of lactation-induced metabolic stress on oocyte developmental competence in the postpartum dairy cow assessed in terms of morphological quality and ability to develop following in vitro fertilization. © 2012 American Dairy Science Association
Influence of lactation on metabolic characteristics and embryo development in postpartum Holstein dairy cows
No full textThe aim of this study was to examine the direct effect of lactation on the ability of the reproductive tract of postpartum dairy cows to support early embryo development. Twenty-one primiparous Holstein heifers were used. Immediately after calving, half of the cows were dried off (i.e.;never milked), and the other half entered the milking herd and were milked twice daily. Jugular blood samples were taken twice per week from 15. d before calving to approximately 100 d postpartum to measure nonesterified fatty acids, β-hydroxybutyrate, glucose, insulin, and insulin-like growth factor-I. At the same time, body weight and body condition score were recorded for each cow. At approximately 60 d postpartum (experiment 1), approximately 65 two- to four-cell embryos, produced by in vitro maturation and fertilization, were endoscopically transferred to the oviduct ipsilateral to the corpus luteum of all cows on d 2 of the estrous cycle. Five days later (d 7), the oviduct and uterus were flushed nonsurgically and the number of embryos developing to the blastocyst stage was recorded. At approximately 90 d postpartum (experiment 2), the estrous cycles of the same cows were resynchronized and 15 to 20 in vitro-produced blastocysts were transferred to the uterus of each recipient on d 7. All cows were slaughtered on d 14 to assess embryo survival and dimensions. Body weight and body condition score were significantly different between groups for the entire postpartum period of the study. Concentrations of nonesterified fatty acids and β-hydroxybutyrate were higher and concentrations of glucose, insulin, and insulin-like growth factor-I were lower in lactating compared with nonlactating cows. Embryo recovery rates from lactating and dry cows were similar. In experiment 1, fewer embryos developed to the blastocyst stage in the lactating cows compared with the nonlactating cows. In experiment 2, embryo survival and conceptus dimensions were not different between lactating and nonlactating cows. In conclusion, the data indicate that the reproductive tract of the lactating dairy cow is compromised in its ability to support early embryo development compared with that of matched dry cows and this may contribute to early embryo mortality observed in such animals. © 2012 American Dairy Science Association
- …
