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Sylvia Bedford-Guaus

Sylvia Bedford-Guaus
Center for Regenerative Medicine in Barcelona · Research

DVM, MS, PhD

About

40
Publications
10,346
Reads
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878
Citations
Citations since 2017
2 Research Items
371 Citations
2017201820192020202120222023020406080
2017201820192020202120222023020406080
2017201820192020202120222023020406080
2017201820192020202120222023020406080
Additional affiliations
July 2011 - September 2012
Independent Researcher
Independent Researcher
Position
  • Consulting Veterinarian in Equine Theriogenology

Publications

Publications (40)
Article
Full-text available
Neonatal mice have been shown to regenerate their hearts during a transient window of time of approximately 1 week after birth. However, experimental evidence for this phenomenon is not undisputed, because several laboratories have been unable to detect neonatal heart regeneration. We first confirmed that 1-day-old neonatal mice are indeed able to...
Article
While vitrification has become the method of choice for preservation of human oocytes and embryos, cryopreservation of complex tissues and of large yolk-containing cells, remains largely unsuccessful. One critical step in such instances is appropriate permeation while avoiding potentially toxic concentrations of cryoprotectants. Permeation of water...
Article
Full-text available
Conjugated linoleic acid (CLA) isomers can affect the lipid profile and signaling of cells and thereby alter their function. A total of 5,700 bovine oocytes were used in a structured series of experiments to test the effects of cis-9,trans-11 CLA and trans-10,cis-12 CLA in vitro. In experiment 1, high doses of each CLA isomer during in vitro matura...
Article
Full-text available
Objective: To evaluate the efficiency of foal production following intracytoplasmic sperm injection (ICSI) and blastocyst culture of oocytes from mares that died or were euthanized under field conditions. Design: Prospective case series. Animals: 16 mares (age, 3 to 19 years) that died or were euthanized for various causes. Procedures: Ovari...
Article
In all mammalian species studied thus far, fertilization results in a series of intracellular Ca2þ ([Ca2þ]i) increases, referred to as oscillations, responsible for driving oocyte activation and embryonic development. Current evidence supports the notion that sperm-borne phospholipase C zeta (PLCZ) is responsible for the initiation of these [Ca2þ]i...
Article
Premature luteal demise or luteal insufficiency is not well characterised as a cause of pregnancy loss in domestic species, including horses. In this report, a mare inseminated with cooled-transported semen at our facility returned for a routine pregnancy diagnosis at 15 days post ovulation. Ultrasonography per rectum revealed endometrial oedema an...
Article
Full-text available
Capacitation encompasses the molecular changes sperm undergo to fertilize an oocyte, some of which are postulated to occur via a cAMP-PRKACA (protein kinase A)-mediated pathway. Due to the recent discovery of cAMP-activated guanine nucleotide exchange factors RAPGEF3 and RAPGEF4, we sought to investigate the separate roles of PRKACA and RAPGEF3/RAP...
Article
Full-text available
Oocyte activation at fertilization is brought about by the testis-specific phospholipase C zeta (PLCZ), owing to its ability to induce oscillations in intracellular Ca(2+) concentration ([Ca(2+)](i)). Whereas this is a highly conserved mechanism among mammals, important species-specific differences in PLCZ sequence, activity, and expression have be...
Article
Full-text available
We evaluated the effect of different activation methods on blastocyst development after equine nuclear transfer. All activation treatments were followed by incubation in 2 mM 6-dimethylaminopurine for 4 h. In Experiment 1, reconstructed oocytes were injected with sperm extract for 0.1, 0.2, 0.4, 0.8, or 1.6 sec using a FemtoJet injection device, th...
Article
Full-text available
Capacitation is a complex and not well-understood process that encompasses all the molecular changes sperm must undergo to successfully fertilize an oocyte. In vitro fertilization has remained elusive in the horse, as evidenced by low in vitro fertilization (IVF) rates (0%-33%); moreover, only two foals have ever been produced using IVF. Incubation...
Article
The sperm-delivered factor responsible for the initiation of intracellular calcium oscillations ([Ca²⁺]i) and thus embryonic development at fertilization has been recently identified as the testis-specific phospholipase C zeta (PLCζ). Although the nature of the [Ca²⁺]i-releasing mechanism at fertilization is highly conserved among mammals, there ar...
Article
Efficient in vitro capacitation of stallion sperm has not yet been achieved, as suggested by low sperm penetration rates reported in in vitro fertilization (IVF) studies. Our objectives were to evaluate defined incubation conditions that would support changes consistent with capacitation in stallion sperm. Protein tyrosine phosphorylation events an...
Article
Full-text available
Methods presently used to activate mare oocytes for assisted reproduction technologies provide low rates of advanced embryonic development. Because phospholipase Czeta (PLCzeta) is the postulated sperm-borne factor responsible for oocyte activation at fertilisation, the aim of the present study was to investigate the pattern of [Ca(2+)](i) oscillat...
Article
In the horse, rates of blastocyst production after nuclear transfer are low. This study was conducted to examine the effect of activation via injection of different volumes of sperm extract or via injection of murine mRNA for PLC-ζ, a sperm-specific protein which induces Ca2+ oscillations in all species thus far studied, on blastocyst development a...
Article
Horse owners worldwide now request that their mares be bred with cooled or frozen-thawed transported semen, owing to the advantages of avoiding mare transport (often with a foal by her side), decreasing disease transmission between farms, and most importantly, the accessibility to a wider genetic pool. This has become commonplace practice as many b...
Article
Although diagnosing cancer during pregnancy is uncommon in veterinary medicine, when it occurs, chemotherapy may represent a reasonable treatment option. A major consideration is that physiological changes associated with pregnancy affect drug pharmacokinetics and complicate correct dosing of chemotherapy agents. Additionally, most antineoplastic d...
Article
Full-text available
In all species studied, fertilization induces intracellular Ca21 ([Ca21]i) oscillations required for oocyte activation and embryonic development. This species-specific pattern has not been studied in the equine, partly due to the difficulties linked to in vitro fertilization in this species. Therefore, the objective of this study was to use intracy...
Article
Full-text available
In oocytes from all mammalian species studied to date, fertilization by a spermatozoon induces intracellular calcium ([Ca(2+)](i)) oscillations that are crucial for appropriate oocyte activation and embryonic development. Such patterns are species-specific and have not yet been elucidated in horses; it is also not known whether equine oocytes respo...
Article
Full-text available
In oocytes from all mammalian species studied to date, fertilization by a spermatozoon induces intracellular calcium ([Ca2+]i) oscillations that are crucial for appropriate oocyte activation and embryonic development. Such patterns are species-specific and have not yet been elucidated in horses; it is also not known whether equine oocytes respond w...
Article
Full-text available
A 14-year-old Arabian stallion was examined because of acute hemospermia. The stallion was used in an artificial breeding program and had a 6-year history of low-grade hemospermia and a 4-year history of self-mutilation behavior. During previous examinations, minor irritation of the urethral process was identified as the source of the bleeding. Phy...
Article
The effects of cryopreservation on the acrosomal status of equine spermatozoa were investigated. Ejaculates (n=10) from six stallions were processed fresh, after cooled storage at 4-6 degrees C for 24 h in either a milk-based or lactose-EDTA freezing extender and after freeze-thawing in lactose-EDTA extender in liquid nitrogen at either 5 x 10(7) o...
Article
Full-text available
To evaluate the effects of trimethoprim-sulfamethoxazole and pyrimethamine treatment on various measures of reproductive function in healthy pony stallions. Randomized complete block study. 12 healthy, mature pony stallions. Stallions were assigned to treatment and control groups balanced for age and various characteristics of reproductive function...
Article
This study was designed to compare the effects of different media and containers on longevity of motility of spermatozoa during in vitro incubation at 38°C in either air or 5% CO2 atmosphere. Three ejaculates were collected from each of 4 stallions. The media tested were skim milk-glucose, modified Krebs/Ringer and Hank's salts solution for incubat...
Article
Following parturition, a female llama was admitted to our hospital with a tear in the dorsal area of the vagina and peritonitis. The llama was clinically normal for 7 days after which its condition started to deteriorate, and the llama died 11 days after admission. On necropsy examination, the intact placenta was found in the abdominal cavity. Ther...
Article
'Three experiments were conducted to evaluate the effects of egg yolk and(or) glycerol added to a nonfat dried skim milk-glucose (NDSMG) extender on motion characteristics and fertility of stallion spermatozoa. In Experiment 1, ejaculates from each of 8 stallions were exposed to each of 4 extender treatments: 1) NDSMG, 2) NDSMG + 4% egg yolk (EY),...
Article
Motion characteristics of cooled stallion spermatozoa in 2 freezing extenders were studied. Ejaculates from 8 stallions were split into treatments and cooled in thermoelectric cooling units at each of 2 rates. Cooling started at 37OC for Experiments 1 and 3 and at 23OC for Experiments 2 and 4, at a rate of -0.7°C/min to 20°C and from 20 to 5OC, at...
Article
It has recently been reported that large insemination volumes might affect fertility of mares. The results from these studies are confounded by other factors, however, such as inadequate number of spermatozoa in the inseminate. We conducted a study to test whether volume alone affects fertility when sufficient numbers of spermatozoa are present. Se...
Article
Full-text available
The control of bacteria in semen of stallions has been most effective with the use of seminal extenders containing suitable ~ncen~tions of antibiotics. Wowever, the detrimental effect of antibiotics on sperm motility may be greater in stored, cooled semen due to the prolonged exposure to the semiotic. Therefore, a study was conducted to determine t...

Questions

Questions (6)
Question
We are trying to encapsulate cell extracts and would need to follow the efficiency of such encapsulation. Need to be able to visualize them under a microscope, fluorescent or not. We have thought about labeling microtubules or microfilaments but not sure if this will be efficient enough or if there are such elements left in a crude cell extract. This is a crude extract of somatic cells prepared by sonication and centrifugation. Our asumption is that the extract will contain membranes, cytoskeletal elements and proteins, but not sure. Thank you in advance for any advice or if you can suggest any references.
Question
Hello Colleagues,
This may be a trivial question but would like to be sure. 
I bought a lipid formulation with three different phospholipids and they reported this was at a 76:19:5 mole%. When I asked what this meant, I was told that in my 1 mg vials I had 0.76 mg of A, 0.19 mg of B, and 0.05 mg of C. 
I was surprised by this as I thought that mole% would imply a calculation that used the MW of each component. However, it was just a simple mass (mg) percent. Am I understanding this correctly?
Thank you in advance.
Sincerely,
Sylvia Bedford
Question
Hello Colleagues,
I have vials of a phospholipid formulation that I will use to prepare lipososomes. Once opened, I will not be using each vial immediately. Most researchers report using something like ethanol to prepare a stock solution, but then for storage they gas the vial with Argon and store at -20oC. If this is absolutely necessary I would probably have to purchase an argon tank just for this purpose. 
I was wondering:
1) What is the purpose of the argon gassing (prevent oxidation?)
2) Is there an alternative to argon gassing for adequate storage of these lipids?
Any other advice highly appreciated. 
Sincerely, Sylvia Bedford
Question
Hello - Can anyone give me insight as to potential markers that could be used to bind and mark the cytoskeleton of mouse oocytes? However, I would want to use these in live oocytes (devoid of their ZP), so the marker/fluorophore should be cell permeable. Is this feasible?
Thank you very much in advance.
Question
Hello - Can anyone please direct me to a reference that may give morphometry data on mouse oocytes, both at GV and MII stages? Basically I have an idea that the mouse oocyte measures at 70 um in diameter. However, would like to know with a little more exactitude if there is a lot of variations between strains, individuals, and within mice. I also need to know if the size counts on the ZP or just the diameter of the actual membrane enclosed cell. Thank you in advance.
Question
Hello - I need to retrieve GV stage oocytes from mice ovaries. I do not know where to get the small tool that is used to mush the ovaries into small pieces. I do not know how to fabricate it either. Does anyone know if it is commercially available? If not, do you have any spares you are willing to part with? Thank you very much in advance.

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