Jose de Los Santos - Academia.edu (original) (raw)

Papers by Jose de Los Santos

Research paper thumbnail of PP-26 pH DYNAMICS IN IVF CULTURE MEDIA

Reproductive BioMedicine Online, 2012

Research paper thumbnail of PP-047 - Hatching timing and blastocyst quality: Implications on implantation window

Reproductive BioMedicine Online, 2016

Research paper thumbnail of Embryo cohort determines the fate of good quality sibling embryos

Fert Steril, 2001

Objective: Human spermatozoa undergoes acrosome reactions (AR) in order to penetrate the zona pel... more Objective: Human spermatozoa undergoes acrosome reactions (AR) in order to penetrate the zona pellucida and fuse with the oolemma, thus fertilizing the oocyte. Previous investigations on the effect of different factors like smoking and aging have resulted in conflicting reports on its effect to induce the AR.

Research paper thumbnail of The Metabolomic Profile of Spent Culture Media from Day-3 Human Embryos Cultured under Low Oxygen Tension

PLOS ONE, 2015

Despite efforts made to improve the in vitro embryo culture conditions used during assisted repro... more Despite efforts made to improve the in vitro embryo culture conditions used during assisted reproduction procedures, human embryos must adapt to different in vitro oxygen concentrations and the new metabolic milieu provided by the diverse culture media used for such protocols. It has been shown that the embryo culture environment can affect not only cellular metabolism, but also gene expression in different species of mammalian embryos. Therefore we wanted to compare the metabolic footprint left by human cleavage-stage embryos under two types of oxygen atmospheric culture conditions (6% and 20% O2). The spent culture media from 39 transferred and implanted embryos from a total of 22 patients undergoing egg donation treatment was analyzed; 23 embryos came from 13 patients in the 6% oxygen concentration group, and 16 embryos from 9 patients were used in the 20% oxygen concentration group. The multivariate statistics we used in our analysis showed that human cleavage-stage embryos grown under both types of oxygen concentration left a similar metabolic fingerprint. We failed to observe any change in the net depletion or release of relevant analytes, such as glucose and especially fatty acids, by human cleavage-stage embryos under either type of culture condition. Therefore it seems that low oxygen tension during embryo culture does not alter the global metabolism of human cleavage-stage embryos.

Research paper thumbnail of Effect of a sharp serum oestradiol fall before HCG administration during ovarian stimulation in donors

Reproductive BioMedicine Online, 2007

The current study evaluated how a sudden fall in serum oestradiol during ovarian stimulation in d... more The current study evaluated how a sudden fall in serum oestradiol during ovarian stimulation in donors affects recipient outcome. After the assessment of pregnancy rate in cases of oestradiol falls of <10 or ≥10% (57.0 versus 45.6%), <20 or ≥20% (55.2 versus 44.9%), <25 or ≥25% (57.2 versus 41.2%), and <30 or ≥30% (57.1 versus 32.0%; P < 0.05), a significantly lower pregnancy rate was observed when the fall was ≥30%. Therefore, the study group (n = 25) included recipients who received oocytes from donors with a fall of ≥30%, and the control group included patients (n = 197) in which the fall in oestradiol was <30% and all cases with no fall in oestradiol concentrations. Pregnancy rates in both groups were 32.0 versus 57.1%; P < 0.05. The number of morphologically normal oocytes was similar (14.2 versus 18.1%) and good quality embryos was lower (8.0 versus 21.0%; P < 0.05) for study group. This seems related to a lower capability of the embryos to implant (15.2 versus 37.4%; P < 0.001). These data indicate that a fall of ≥30% in serum oestradiol concentration during ovarian stimulation in donors negatively affects pregnancy rates and embryo quality in recipients. In these cases, cycle cancellation should be considered.

Research paper thumbnail of Grain-oriented ternary systems based on lead titanate zirconate ceramics

High Temperatures-High Pressures, 1998

Research paper thumbnail of “Vintage” in sperm cryopreservation: droplets in liquefied air

Reproductive BioMedicine Online, 2014

Cryopreservation of human spermatozoa is an essential procedure during ART treatments. Various pr... more Cryopreservation of human spermatozoa is an essential procedure during ART treatments. Various protocols and technologies were reported, most of which were quite successful. Most protocols are using LN2 for the procedure. The risk of using LN2 for the preservation of gametes due to the presence of viruses and/or bacteria has, massively, been discussed. In this preliminary work we describe a simple method, based on the first report of sperm cryopreservation (Luyet 1938) creating droplets of 10µl and a solution developed by IVI (ASRM 2013) but using sterile clean liquid air (CLair). Materials and Methods: Freezing: Ejaculated sperm were first analyzed for count and motility, subsequently washed to remove seminal plasma and then diluted 1:1 in Hepes medium containing 0.125 M sucrose, 0.125 M trehalose and 3% human serum albumin.

Research paper thumbnail of PP-35 is the Site of the Hatching Initiation Affecting the Implantation Potential of Human Blastocysts?

Reproductive BioMedicine Online, 2012

Research paper thumbnail of A multicenter prospective study to assess the effect of early cleavage on embryo quality, implantation, and live-birth rate

Fertility and Sterility, 2014

To investigate the impact of early cleavage (EC) on embryo quality, implantation, and live-birth ... more To investigate the impact of early cleavage (EC) on embryo quality, implantation, and live-birth rates. Prospective cross-sectional study. Multicenter study. Seven hundred embryo transfers and 1,028 early-stage human embryos. None. Implantation according to the presence of EC and embryo quality. The presence of EC is associated with embryo quality, especially in cycles with autologous oocytes. However, the use of EC as an additional criterion for selecting an embryo for transfer does not appear to significantly improve likelihood of implantation. Furthermore, embryos that presented EC had live-birth rates per implanted embryo similar to those that did not show any sign of cleavage. At least for conventional embryo culture and morphologic evaluations, the additional evaluation of EC in embryos may not be valuable to improve embryo implantation.

Research paper thumbnail of Outcomes of vitrified early cleavage-stage and blastocyst-stage embryos in a cryopreservation program: evaluation of 3,150 warming cycles

Fertility and Sterility, 2012

Objective: To assess the outcomes achieved after Cryotop vitrification of both early cleavage and... more Objective: To assess the outcomes achieved after Cryotop vitrification of both early cleavage and blastocyst-stage embryos and to determine whether the embryo developmental stage and embryo quality as well as the origin of the embryos (ovum donation cycles, patients' own oocytes) and the endometrial preparation for the embryo transfer had any effect on the final outcome. Design: Observational study. Setting: Private university-affiliated IVF center. Patient(s): Women undergoing 3,150 warming cycles whose embryos were vitrified due to various reasons.

Research paper thumbnail of Outcome of cryotransfer of embryos developed from vitrified oocytes: double vitrification has no impact on delivery rates

Fertility and Sterility, 2013

Evaluate the outcome of cryotransfer of embryos developed from vitrified oocytes. Retrospective c... more Evaluate the outcome of cryotransfer of embryos developed from vitrified oocytes. Retrospective cohort study. Private university-affiliated IVF center. Women undergoing warming cycles in which vitrified embryos were developed from vitrified or fresh oocytes. Vitrification by the Cryotop open device. Delivery rate (DR) per warming cycle. A total of 471 warming cycles of 796 vitrified embryos developed from vitrified oocytes (group 1) and 2,629 warming cycles of 4,394 vitrified embryos derived from fresh oocytes (group 2) were evaluated. Overall survival rates were 97.2% [95% confidence interval [CI] 95.9%-98.6%] vs. 95.7% [95% CI 94.9-96.4], respectively. DRs per warming cycle were 33.8% (group 1) and 30.9% (group 2). Double vitrification had no effect on DR (odds ratio [OR] 0.877, 95% CI 0.712-1.080). Confounding factors (ovum donation or autologous cycles; day-3 or blastocyst embryo transfer [ET]; natural or hormonal replacement therapy for ET; single or double ET; previous cycles, number of oocytes, doses of gonadotropins and E2 levels on the day of hCG) did not modify the effect of double vitrification on DR (OR 0.872, 95% CI 0.702-1.084). Vitrification at early cleavage or blastocyst stage of embryos obtained from previously vitrified oocytes has no effect on DR/warming cycle.

Research paper thumbnail of Value of the sperm deoxyribonucleic acid fragmentation level, as measured by the sperm chromatin dispersion test, in the outcome of in vitro fertilization and intracytoplasmic sperm injection

Fertility and Sterility, 2006

To determine the prognostic value of sperm DNA fragmentation levels, as measured by the sperm chr... more To determine the prognostic value of sperm DNA fragmentation levels, as measured by the sperm chromatin dispersion (SCD) test, in predicting IVF and ICSI outcome. Design: Double-blind prospective study. Setting: University-affiliated private IVF setting. Patient(s): A total of 85 couples undergoing infertility treatment with IVF/ICSI. Intervention(s): Analysis of DNA fragmentation by the SCD test in 170 aliquots obtained from the ejaculate and from the processed semen used for assisted reproductive technologies (ART). Main Outcome Measure(s): Percentage of spermatozoa with fragmented DNA was statistically correlated with embryo quality and reproductive success. Result(s): Fertilization rate was inversely correlated with DNA fragmentation (r ϭ Ϫ0.245 Pϭ.045). Higher DNA fragmentation rate gave an increased proportion of zygotes showing asynchrony between the nucleolar precursor bodies of zygote pronuclei (73.8% vs. 28.8% PϽ.001). In addition, the slower embryo development and worst morphology on day 6 was correlated with higher sperm DNA fragmentation (47.7% vs. 29.4% Pϭ.044). We also observed a negative correlation between DNA fragmentation and the implantation rate (r ϭ Ϫ0.250 Pϭ.042). However, SCD test values were not statistically different in cycles that resulted in a pregnancy compared with those that did not (33.2 vs. 28.2 and 32.4 vs. 34.7).

Research paper thumbnail of Storage of human oocytes in the vapor phase of nitrogen

Fertility and Sterility, 2010

Objective: To evaluate the effectiveness of long-term vapor-phase nitrogen storage of vitrified h... more Objective: To evaluate the effectiveness of long-term vapor-phase nitrogen storage of vitrified human oocytes as a strategy for preventing the risk of cross-contamination due to direct contact with the liquid nitrogen (LN). Design: Prospective randomized study. Setting: Private infertility center, IVI, Valencia. Patient(s): Oocyte donors (n ¼ 44) and recipients (n ¼ 46). Intervention(s): Vitrification by the Cryotop method. Storage of vitrified oocytes in a vapor-phase nitrogen storage freezer and a traditional LN storage tank. Donation of the surviving oocytes and evaluation of fertilization, embryo development, and clinical results. Main Outcome Measure(s): Survival, fertilization, and cleavage rates. Embryo quality and clinical outcome.

Research paper thumbnail of Presence of Fas-Fas Ligand System and Bcl-2 Gene Products in Cells and Fluids from Gonadotropin-Stimulated Human Ovaries1

Biology of Reproduction, 2000

Apoptosis, or programmed cell death, is an important mechanism for the regulation of embryonic de... more Apoptosis, or programmed cell death, is an important mechanism for the regulation of embryonic development and tissue homeostasis. It is coordinated by a number of molecules including the Fas-Fas ligand (FasL) system and bcl-2. The purpose of this study was to characterize the expression of these molecules in human oocytes and cumulus cells from gonadotropin-stimulated human ovaries and to determine whether the presence of soluble Fas (sFas), soluble FasL, or interferon-gamma in follicular fluid (FF) correlated with apoptosis in cumulus cells, oocyte maturation, and embryo quality. Levels of sFas were significantly higher in FF containing immature oocytes compared with those containing atretic oocytes (P &amp;amp;amp;amp;amp;amp;lt; 0.05; FF containing mature oocytes had highly variable levels of sFas. Levels of sFas in FF did not correlate with either fertilization, embryo quality resulting from fertilized oocytes, or apoptosis rate in cumulus cells. Fas was expressed in both unfertilized oocytes and cumulus cells, whereas FasL expression was not usually detected in these cell types. Messenger RNA for bcl-2 was detectable in both freshly isolated oocytes and cumulus cells but was not demonstrable following 24 h of culture that coincided with a significant increase of apoptosis in cumulus cells. Our results indicate that soluble forms of the Fas-FasL system are present in FF from gonadotropin-stimulated human ovaries and suggest that this system may play a role in preventing oocyte atresia during folliculogenesis but is probably not important for apoptotic events in cumulus cells and oocytes after fertilization failure. Apoptosis in this case may be facilitated by the downregulation of bcl-2. Further studies on the expression of these molecules in follicles containing atretic oocytes and immature oocytes are needed to confirm this new hypothesis.

Research paper thumbnail of Expression of Interleukin-1 System Genes in Human Gametes

Biology of Reproduction, 1998

There is considerable evidence that the interleukin-1 (IL-1) system plays an important role in ov... more There is considerable evidence that the interleukin-1 (IL-1) system plays an important role in ovarian and testicular physiology, implantation, and other reproductive events. Human embryos express IL-1beta, IL-1 receptor type I (IL-1RtI), and IL-1 receptor antagonist (IL-1RA) at both the mRNA and protein levels. The presence of IL-1alpha and IL-1beta in oocyte-conditioned media and on the surface of human oocytes suggests that these cells may also produce this cytokine; however, whether the IL-1 system gene products are present as stable mRNAs in human gametes (oocytes and spermatozoa) has not yet been demonstrated. We used stringent cell separation techniques combined with reverse transcription-polymerase chain reaction to investigate the expression of various IL-1 system genes (IL-1alpha, IL-1beta, IL-1RtI, and IL-1RA) in human gametes and cumulus cells. Our results indicate that freshly isolated cumulus cells express all these IL-1 system components. On the other hand, IL-1alpha, IL-1beta, and IL-1RtI mRNAs were not found in either unfertilized or fertilized human oocytes, and a very few metaphase II human oocytes had transcripts for either secreted (10%) or intracellular (17%) IL-1RA. Mature spermatozoa did not contain mRNA for any of the of the IL-1 system components. The absence of informational RNA for the IL-1 system components in human unfertilized and polyploid oocytes and fresh immature oocytes suggests that maternal transcripts for these genes do not contribute to early embryo development. The presence of IL-1 components at the protein level in human oocytes may be due to binding of IL-1 produced by cumulus cells or other cell types, or to prior intrafollicle transcription and translation. Likewise, IL-1 system components do not appear to have a physiological role in mature spermatozoa since none of these components are present at the mRNA or protein levels, and important functional parameters such as motility and acrosome reaction appear not to be affected by IL-1beta in vitro. However, the abundant expression of IL-1alpha, IL-1beta, the IL-1RtI, and its antagonist IL-1RA by human cumulus cells provides further evidence that the IL-1 system plays a role in human ovarian physiology.

Research paper thumbnail of Combination of metabolism measurement and a time-lapse system provides an embryo selection method based on oxygen uptake and chronology of cytokinesis timing

Fertility and Sterility, 2016

To evaluate correlations between oxygen consumption (OC) measurements before and after embryo cyt... more To evaluate correlations between oxygen consumption (OC) measurements before and after embryo cytokinesis, observing OC during embryo cleavages and combining that information with morphokinetics to relate to implantation potential. Prospective cohort study. University-affiliated private IVF unit. A total of 1,150 injected oocytes in 86 first oocyte donation cycles with embryo transfer on day 3. None. We analyzed the embryo OC and combined this data with the cytokinesis event, exact timing (in hours) of blastomeric cleavages, with the use of an incubator equipped with time-lapse videography, gathering a total of 7,630 measurements during the cytokinesis (active phase) and consecutive measurements after this division (passive phase), correlating this data with embryo outcome. OC was found to increase during embryo cleavage, showing high levels during first division with a strong correlation with implantation success. Moreover, those embryos with slow or fast development gave rise to lower OC levels, whereas higher levels were associated with optimal embryo division ranges linked to higher implantation potential. A detailed analysis of OC by time-lapse observations enhances the value that these measurements represented as markers of embryo quality, especially during the cytokinesis events produced during preimplantation development.

Research paper thumbnail of PP-26 pH DYNAMICS IN IVF CULTURE MEDIA

Reproductive BioMedicine Online, 2012

Research paper thumbnail of PP-047 - Hatching timing and blastocyst quality: Implications on implantation window

Reproductive BioMedicine Online, 2016

Research paper thumbnail of Embryo cohort determines the fate of good quality sibling embryos

Fert Steril, 2001

Objective: Human spermatozoa undergoes acrosome reactions (AR) in order to penetrate the zona pel... more Objective: Human spermatozoa undergoes acrosome reactions (AR) in order to penetrate the zona pellucida and fuse with the oolemma, thus fertilizing the oocyte. Previous investigations on the effect of different factors like smoking and aging have resulted in conflicting reports on its effect to induce the AR.

Research paper thumbnail of The Metabolomic Profile of Spent Culture Media from Day-3 Human Embryos Cultured under Low Oxygen Tension

PLOS ONE, 2015

Despite efforts made to improve the in vitro embryo culture conditions used during assisted repro... more Despite efforts made to improve the in vitro embryo culture conditions used during assisted reproduction procedures, human embryos must adapt to different in vitro oxygen concentrations and the new metabolic milieu provided by the diverse culture media used for such protocols. It has been shown that the embryo culture environment can affect not only cellular metabolism, but also gene expression in different species of mammalian embryos. Therefore we wanted to compare the metabolic footprint left by human cleavage-stage embryos under two types of oxygen atmospheric culture conditions (6% and 20% O2). The spent culture media from 39 transferred and implanted embryos from a total of 22 patients undergoing egg donation treatment was analyzed; 23 embryos came from 13 patients in the 6% oxygen concentration group, and 16 embryos from 9 patients were used in the 20% oxygen concentration group. The multivariate statistics we used in our analysis showed that human cleavage-stage embryos grown under both types of oxygen concentration left a similar metabolic fingerprint. We failed to observe any change in the net depletion or release of relevant analytes, such as glucose and especially fatty acids, by human cleavage-stage embryos under either type of culture condition. Therefore it seems that low oxygen tension during embryo culture does not alter the global metabolism of human cleavage-stage embryos.

Research paper thumbnail of Effect of a sharp serum oestradiol fall before HCG administration during ovarian stimulation in donors

Reproductive BioMedicine Online, 2007

The current study evaluated how a sudden fall in serum oestradiol during ovarian stimulation in d... more The current study evaluated how a sudden fall in serum oestradiol during ovarian stimulation in donors affects recipient outcome. After the assessment of pregnancy rate in cases of oestradiol falls of <10 or ≥10% (57.0 versus 45.6%), <20 or ≥20% (55.2 versus 44.9%), <25 or ≥25% (57.2 versus 41.2%), and <30 or ≥30% (57.1 versus 32.0%; P < 0.05), a significantly lower pregnancy rate was observed when the fall was ≥30%. Therefore, the study group (n = 25) included recipients who received oocytes from donors with a fall of ≥30%, and the control group included patients (n = 197) in which the fall in oestradiol was <30% and all cases with no fall in oestradiol concentrations. Pregnancy rates in both groups were 32.0 versus 57.1%; P < 0.05. The number of morphologically normal oocytes was similar (14.2 versus 18.1%) and good quality embryos was lower (8.0 versus 21.0%; P < 0.05) for study group. This seems related to a lower capability of the embryos to implant (15.2 versus 37.4%; P < 0.001). These data indicate that a fall of ≥30% in serum oestradiol concentration during ovarian stimulation in donors negatively affects pregnancy rates and embryo quality in recipients. In these cases, cycle cancellation should be considered.

Research paper thumbnail of Grain-oriented ternary systems based on lead titanate zirconate ceramics

High Temperatures-High Pressures, 1998

Research paper thumbnail of “Vintage” in sperm cryopreservation: droplets in liquefied air

Reproductive BioMedicine Online, 2014

Cryopreservation of human spermatozoa is an essential procedure during ART treatments. Various pr... more Cryopreservation of human spermatozoa is an essential procedure during ART treatments. Various protocols and technologies were reported, most of which were quite successful. Most protocols are using LN2 for the procedure. The risk of using LN2 for the preservation of gametes due to the presence of viruses and/or bacteria has, massively, been discussed. In this preliminary work we describe a simple method, based on the first report of sperm cryopreservation (Luyet 1938) creating droplets of 10µl and a solution developed by IVI (ASRM 2013) but using sterile clean liquid air (CLair). Materials and Methods: Freezing: Ejaculated sperm were first analyzed for count and motility, subsequently washed to remove seminal plasma and then diluted 1:1 in Hepes medium containing 0.125 M sucrose, 0.125 M trehalose and 3% human serum albumin.

Research paper thumbnail of PP-35 is the Site of the Hatching Initiation Affecting the Implantation Potential of Human Blastocysts?

Reproductive BioMedicine Online, 2012

Research paper thumbnail of A multicenter prospective study to assess the effect of early cleavage on embryo quality, implantation, and live-birth rate

Fertility and Sterility, 2014

To investigate the impact of early cleavage (EC) on embryo quality, implantation, and live-birth ... more To investigate the impact of early cleavage (EC) on embryo quality, implantation, and live-birth rates. Prospective cross-sectional study. Multicenter study. Seven hundred embryo transfers and 1,028 early-stage human embryos. None. Implantation according to the presence of EC and embryo quality. The presence of EC is associated with embryo quality, especially in cycles with autologous oocytes. However, the use of EC as an additional criterion for selecting an embryo for transfer does not appear to significantly improve likelihood of implantation. Furthermore, embryos that presented EC had live-birth rates per implanted embryo similar to those that did not show any sign of cleavage. At least for conventional embryo culture and morphologic evaluations, the additional evaluation of EC in embryos may not be valuable to improve embryo implantation.

Research paper thumbnail of Outcomes of vitrified early cleavage-stage and blastocyst-stage embryos in a cryopreservation program: evaluation of 3,150 warming cycles

Fertility and Sterility, 2012

Objective: To assess the outcomes achieved after Cryotop vitrification of both early cleavage and... more Objective: To assess the outcomes achieved after Cryotop vitrification of both early cleavage and blastocyst-stage embryos and to determine whether the embryo developmental stage and embryo quality as well as the origin of the embryos (ovum donation cycles, patients' own oocytes) and the endometrial preparation for the embryo transfer had any effect on the final outcome. Design: Observational study. Setting: Private university-affiliated IVF center. Patient(s): Women undergoing 3,150 warming cycles whose embryos were vitrified due to various reasons.

Research paper thumbnail of Outcome of cryotransfer of embryos developed from vitrified oocytes: double vitrification has no impact on delivery rates

Fertility and Sterility, 2013

Evaluate the outcome of cryotransfer of embryos developed from vitrified oocytes. Retrospective c... more Evaluate the outcome of cryotransfer of embryos developed from vitrified oocytes. Retrospective cohort study. Private university-affiliated IVF center. Women undergoing warming cycles in which vitrified embryos were developed from vitrified or fresh oocytes. Vitrification by the Cryotop open device. Delivery rate (DR) per warming cycle. A total of 471 warming cycles of 796 vitrified embryos developed from vitrified oocytes (group 1) and 2,629 warming cycles of 4,394 vitrified embryos derived from fresh oocytes (group 2) were evaluated. Overall survival rates were 97.2% [95% confidence interval [CI] 95.9%-98.6%] vs. 95.7% [95% CI 94.9-96.4], respectively. DRs per warming cycle were 33.8% (group 1) and 30.9% (group 2). Double vitrification had no effect on DR (odds ratio [OR] 0.877, 95% CI 0.712-1.080). Confounding factors (ovum donation or autologous cycles; day-3 or blastocyst embryo transfer [ET]; natural or hormonal replacement therapy for ET; single or double ET; previous cycles, number of oocytes, doses of gonadotropins and E2 levels on the day of hCG) did not modify the effect of double vitrification on DR (OR 0.872, 95% CI 0.702-1.084). Vitrification at early cleavage or blastocyst stage of embryos obtained from previously vitrified oocytes has no effect on DR/warming cycle.

Research paper thumbnail of Value of the sperm deoxyribonucleic acid fragmentation level, as measured by the sperm chromatin dispersion test, in the outcome of in vitro fertilization and intracytoplasmic sperm injection

Fertility and Sterility, 2006

To determine the prognostic value of sperm DNA fragmentation levels, as measured by the sperm chr... more To determine the prognostic value of sperm DNA fragmentation levels, as measured by the sperm chromatin dispersion (SCD) test, in predicting IVF and ICSI outcome. Design: Double-blind prospective study. Setting: University-affiliated private IVF setting. Patient(s): A total of 85 couples undergoing infertility treatment with IVF/ICSI. Intervention(s): Analysis of DNA fragmentation by the SCD test in 170 aliquots obtained from the ejaculate and from the processed semen used for assisted reproductive technologies (ART). Main Outcome Measure(s): Percentage of spermatozoa with fragmented DNA was statistically correlated with embryo quality and reproductive success. Result(s): Fertilization rate was inversely correlated with DNA fragmentation (r ϭ Ϫ0.245 Pϭ.045). Higher DNA fragmentation rate gave an increased proportion of zygotes showing asynchrony between the nucleolar precursor bodies of zygote pronuclei (73.8% vs. 28.8% PϽ.001). In addition, the slower embryo development and worst morphology on day 6 was correlated with higher sperm DNA fragmentation (47.7% vs. 29.4% Pϭ.044). We also observed a negative correlation between DNA fragmentation and the implantation rate (r ϭ Ϫ0.250 Pϭ.042). However, SCD test values were not statistically different in cycles that resulted in a pregnancy compared with those that did not (33.2 vs. 28.2 and 32.4 vs. 34.7).

Research paper thumbnail of Storage of human oocytes in the vapor phase of nitrogen

Fertility and Sterility, 2010

Objective: To evaluate the effectiveness of long-term vapor-phase nitrogen storage of vitrified h... more Objective: To evaluate the effectiveness of long-term vapor-phase nitrogen storage of vitrified human oocytes as a strategy for preventing the risk of cross-contamination due to direct contact with the liquid nitrogen (LN). Design: Prospective randomized study. Setting: Private infertility center, IVI, Valencia. Patient(s): Oocyte donors (n ¼ 44) and recipients (n ¼ 46). Intervention(s): Vitrification by the Cryotop method. Storage of vitrified oocytes in a vapor-phase nitrogen storage freezer and a traditional LN storage tank. Donation of the surviving oocytes and evaluation of fertilization, embryo development, and clinical results. Main Outcome Measure(s): Survival, fertilization, and cleavage rates. Embryo quality and clinical outcome.

Research paper thumbnail of Presence of Fas-Fas Ligand System and Bcl-2 Gene Products in Cells and Fluids from Gonadotropin-Stimulated Human Ovaries1

Biology of Reproduction, 2000

Apoptosis, or programmed cell death, is an important mechanism for the regulation of embryonic de... more Apoptosis, or programmed cell death, is an important mechanism for the regulation of embryonic development and tissue homeostasis. It is coordinated by a number of molecules including the Fas-Fas ligand (FasL) system and bcl-2. The purpose of this study was to characterize the expression of these molecules in human oocytes and cumulus cells from gonadotropin-stimulated human ovaries and to determine whether the presence of soluble Fas (sFas), soluble FasL, or interferon-gamma in follicular fluid (FF) correlated with apoptosis in cumulus cells, oocyte maturation, and embryo quality. Levels of sFas were significantly higher in FF containing immature oocytes compared with those containing atretic oocytes (P &amp;amp;amp;amp;amp;amp;lt; 0.05; FF containing mature oocytes had highly variable levels of sFas. Levels of sFas in FF did not correlate with either fertilization, embryo quality resulting from fertilized oocytes, or apoptosis rate in cumulus cells. Fas was expressed in both unfertilized oocytes and cumulus cells, whereas FasL expression was not usually detected in these cell types. Messenger RNA for bcl-2 was detectable in both freshly isolated oocytes and cumulus cells but was not demonstrable following 24 h of culture that coincided with a significant increase of apoptosis in cumulus cells. Our results indicate that soluble forms of the Fas-FasL system are present in FF from gonadotropin-stimulated human ovaries and suggest that this system may play a role in preventing oocyte atresia during folliculogenesis but is probably not important for apoptotic events in cumulus cells and oocytes after fertilization failure. Apoptosis in this case may be facilitated by the downregulation of bcl-2. Further studies on the expression of these molecules in follicles containing atretic oocytes and immature oocytes are needed to confirm this new hypothesis.

Research paper thumbnail of Expression of Interleukin-1 System Genes in Human Gametes

Biology of Reproduction, 1998

There is considerable evidence that the interleukin-1 (IL-1) system plays an important role in ov... more There is considerable evidence that the interleukin-1 (IL-1) system plays an important role in ovarian and testicular physiology, implantation, and other reproductive events. Human embryos express IL-1beta, IL-1 receptor type I (IL-1RtI), and IL-1 receptor antagonist (IL-1RA) at both the mRNA and protein levels. The presence of IL-1alpha and IL-1beta in oocyte-conditioned media and on the surface of human oocytes suggests that these cells may also produce this cytokine; however, whether the IL-1 system gene products are present as stable mRNAs in human gametes (oocytes and spermatozoa) has not yet been demonstrated. We used stringent cell separation techniques combined with reverse transcription-polymerase chain reaction to investigate the expression of various IL-1 system genes (IL-1alpha, IL-1beta, IL-1RtI, and IL-1RA) in human gametes and cumulus cells. Our results indicate that freshly isolated cumulus cells express all these IL-1 system components. On the other hand, IL-1alpha, IL-1beta, and IL-1RtI mRNAs were not found in either unfertilized or fertilized human oocytes, and a very few metaphase II human oocytes had transcripts for either secreted (10%) or intracellular (17%) IL-1RA. Mature spermatozoa did not contain mRNA for any of the of the IL-1 system components. The absence of informational RNA for the IL-1 system components in human unfertilized and polyploid oocytes and fresh immature oocytes suggests that maternal transcripts for these genes do not contribute to early embryo development. The presence of IL-1 components at the protein level in human oocytes may be due to binding of IL-1 produced by cumulus cells or other cell types, or to prior intrafollicle transcription and translation. Likewise, IL-1 system components do not appear to have a physiological role in mature spermatozoa since none of these components are present at the mRNA or protein levels, and important functional parameters such as motility and acrosome reaction appear not to be affected by IL-1beta in vitro. However, the abundant expression of IL-1alpha, IL-1beta, the IL-1RtI, and its antagonist IL-1RA by human cumulus cells provides further evidence that the IL-1 system plays a role in human ovarian physiology.

Research paper thumbnail of Combination of metabolism measurement and a time-lapse system provides an embryo selection method based on oxygen uptake and chronology of cytokinesis timing

Fertility and Sterility, 2016

To evaluate correlations between oxygen consumption (OC) measurements before and after embryo cyt... more To evaluate correlations between oxygen consumption (OC) measurements before and after embryo cytokinesis, observing OC during embryo cleavages and combining that information with morphokinetics to relate to implantation potential. Prospective cohort study. University-affiliated private IVF unit. A total of 1,150 injected oocytes in 86 first oocyte donation cycles with embryo transfer on day 3. None. We analyzed the embryo OC and combined this data with the cytokinesis event, exact timing (in hours) of blastomeric cleavages, with the use of an incubator equipped with time-lapse videography, gathering a total of 7,630 measurements during the cytokinesis (active phase) and consecutive measurements after this division (passive phase), correlating this data with embryo outcome. OC was found to increase during embryo cleavage, showing high levels during first division with a strong correlation with implantation success. Moreover, those embryos with slow or fast development gave rise to lower OC levels, whereas higher levels were associated with optimal embryo division ranges linked to higher implantation potential. A detailed analysis of OC by time-lapse observations enhances the value that these measurements represented as markers of embryo quality, especially during the cytokinesis events produced during preimplantation development.