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Papers by Pedro Osmany Rivera Caballero

Research paper thumbnail of Oxidative stress in follicular fluid of young women with low response compared with fertile oocyte donors

Reproductive BioMedicine Online, 2016

Madrid, where she received her PhD in 1991. She has worked in the area of reproductive technologi... more Madrid, where she received her PhD in 1991. She has worked in the area of reproductive technologies since 1985 and performed a post-doctoral fellowship at the Centre for Research on Reproduction and Women's Health, Philadelphia, USA. Dr Nunez-Calonge has published numerous articles and chapters in scientific journals and books and is referee for a number of Spanish scientific journals. Her primary areas of research are embryology and male infertility.

Research paper thumbnail of ¿A qué velocidad «muere» el ácido desoxirribonucleico del espermatozoide tras descongelar muestras seminales procedentes de donantes?

Revista Internacional de Andrología, 2013

ABSTRACT Objective The study was made to analyze the baseline levels of damage recorded in sperm ... more ABSTRACT Objective The study was made to analyze the baseline levels of damage recorded in sperm DNA fragmentation (SDF) and to estimate sperm DNA longevity as observed in donors after thawing. Material and methods Fifty donors and forty individuals attending a clinic and classified as a normo-zoospermic population were compared. The baseline SDF levels and the increasing rate of SDF (r-SDF) obtained after thawing when the sperm was incubated for a period of 24 h with different sub-sampling performed after 2, 6 and 24 h of incubation were considered as the independent variables and compared. Results Cryopreserved donor sperm exhibited baseline SDF values approximately 2 times lower than those observed in the control group. DNA stability was 2.5 times higher than that observed in the control cohort. Baseline values of SDF of approximately 8% generates 65% sensitivity and 82% specificity to discriminate between the donors and controls. Values of increase of damage of 1.8% per hour, analyzed during the first hours of incubation, identify the donor characteristics with 77% sensibility and 65% specificity. Neither value show any correlation within the control and donor cohorts group. Conclusion The establishment of these types of threshold values can be used to identify donors considered as “super-donors” in relation to their low levels of SDF and high chromatin stability. The donors selected from the different clinics participating in this study showed similar characteristics for these parameters.

Research paper thumbnail of PP-09 Dynamic Analysis of Dna Fragmentation in Fresh Versus Frozen-Thawed Human Spermatozoa

Reproductive BioMedicine Online, 2010

Research paper thumbnail of Antiphospholipid Autoantibodies in Women with Recurrent Gestational Failures – Controversies in Management

Antiphospholipid Syndrome, 2012

Research paper thumbnail of Dynamics of Sperm Dna Fragmentation in Dynamics of Sperm Dna Fragmentation in Fresh and Frozen Human Semen Fresh and Frozen Human Semen

Sperm DNA fragmentation (SDF) must be considered as a dynamic process, i.e. SDF change through ti... more Sperm DNA fragmentation (SDF) must be considered as a dynamic process, i.e. SDF change through time after ejaculation. To analyse the incidence of this phenomenon on sperm quality, the dynamics of SDF was assessed in semen samples before and after freezing. Fifteen donors were included in the analysis and from the same ejaculate three aliquots were obtained. One of them was kept fresh in the seminal plasma and two were frozen-thawed. After thawing one aliquot was maintained in the freezing media and the other capacitated. For analyzing SDF all samples were processed with Halosperm (Halotech DNA SL, Madrid, Spain). Sperm from different aliquots were incubated during a period of 72 hours art 37oC and the rate of SDF at different incubation times (from 0 to 72h) were scored. Results show that the dynamic behaviour of the SDF before and after freezing are different and, in general, after thawing selection of a specific sperm subpopulation, which show less variance in the distribution of SDF values than in fresh samples, was observed. These results indicate that both the management and specially frozen thawing selection of human sperm, for use in assisted reproduction techniques, must be completed quickly in order to minimize the DNA damage. Theoretically, this practice should result in an improvement in pregnancy rates.

Research paper thumbnail of DNA Fragmentation Dynamics in Fresh Versus Frozen Thawed Plus Gradient-Isolated Human Spermatozoa

Systems Biology in Reproductive Medicine, 2010

The aim of this study was to compare the rate of sperm DNA fragmentation (rSDF; increase of SDF o... more The aim of this study was to compare the rate of sperm DNA fragmentation (rSDF; increase of SDF over time) in fresh and gradient isolated frozen-thawed semen samples from male sperm donors of proven fertility. SDF was assessed in the two samples obtained from the same fifteen male donors after 0.5, 1.5, 4.5, 6, 24, 48, and 72 h of incubation in a humidified atmosphere of 5% CO 2 in air at 371C. Analysis was performed based on chromatin dispersion patterns evaluated using the Halosperms kit. No significant differences in SDF were obtained when fresh and gradient-isolated frozen-thawed spermatozoa were compared at baseline. However, the rSDF shown by the two samples differed and gradient-isolation selected for sperm subpopulations showing a lower variance for SDF. At the individual level, sperm selection by density gradient purification in frozen-thawed samples did not improve the levels of SDF when compared with the values obtained in fresh samples at baseline.

Research paper thumbnail of Characterization of sperm DNA damage in Kartagener’s syndrome with recurrent fertilization failure: Case revisited

Sexual & Reproductive Healthcare, 2010

Single-and double-strand sperm DNA breaks was assessed in a Kartagener's syndrome with four failu... more Single-and double-strand sperm DNA breaks was assessed in a Kartagener's syndrome with four failures of fertilization after ISCI in TESA samples. It is concluded that in addition to failure of sperm motility, this patient was infertile because a high level of non-reparable sperm DNA damage was present. Although four cycles of insemination were performed at patient's request, if the argument of an exacerbated level of sperm DNA damage could be used at the time of the medical advice, repeated failed cycles of insemination using ICSI could be avoided. Pregnancy was achieved with a semen donor.

Research paper thumbnail of PP-06 Increased Fertilization Rates After In-Vitro Culture of Frozen Thawed Testicular Immotile Sperm in Non-Obstructive Azoospermic Patients

Reproductive BioMedicine Online, 2010

Research paper thumbnail of PP-37 Improvement of Ivf Outcome by Optimizing the Quality of Laboratory Performance

Reproductive BioMedicine Online, 2012

Research paper thumbnail of PP-8 Evaluation of Sperm Selection Procedure Based on Hyaluronic Acid Binding Ability on the Ivf Success of Donated Oocytes Following Icsi

Reproductive BioMedicine Online, 2012

Research paper thumbnail of OP-1 Intra-Individual Variations in Sperm Dna Fragmentation in Men from Infertile Couples Compared with Fertile Sperm Donors

Reproductive BioMedicine Online, 2012

ABSTRACT Background and Aim: Sperm DNA integrity (SDI) is an important factor in the prognosis of... more ABSTRACT Background and Aim: Sperm DNA integrity (SDI) is an important factor in the prognosis of male fertility. However, it has been noted that SDI can fluctuate over time within certain individuals. The aim of this study was to analyze and compare both within-and between-subject sperm DNA fragmentation (SDF) fluctuations in men presenting to an infertility clinic for semen analysis and in fertile sperm donors. Method: Semen specimens were collected from 51 patients (PS) and from 8 healthy sperm donors (DS). Between 2 and 6 SDF measurements per patient were performed. Fertile donors provided 49 semen samples over a period of 4 months. All samples were divided into three groups, according to the first SDF value: SDF > 30%, SDF >20% <30% and SDF < 20%. Coefficient of variation (CV) for sperm chromatin dispersion (SCD) was calculated using the formula (SD/mean)×100%.

Research paper thumbnail of Defining risk for recurrent gestational failure by blood natural killer cells subsets

Journal of Reproductive Immunology, 2012

Research paper thumbnail of A dynamic assessment of sperm DNA fragmentation versus sperm viability in proven fertile human donors

Fertility and Sterility, 2009

Objective: To analyze any possible dynamic correlation between sperm DNA fragmentation and sperm ... more Objective: To analyze any possible dynamic correlation between sperm DNA fragmentation and sperm viability. Design: The rate of viability loss and the rate of increase of the frequency of sperm cells with fragmented DNA were determined at 0, 1.5, 4.5, and 24.0 hours after thawing samples from donors with proven fertility. Setting: Academic biology and reproductive medicine centers. Patient(s): Fifteen male donors with proven fertility for a maximum of six births at the reproductive medicine center. Intervention(s): None. Main Outcome Measure(s): Sperm DNA fragmentation and viability dynamics expressed as logarithmic coefficients of change. Result(s): The dynamics of sperm DNA fragmentation and sperm viability adjusted to a logarithmic function with an initial highest velocity that progressively decreases. Nevertheless, the rates were not statistically significantly correlated. Conclusion(s): In the short term, dynamic dysfunction of membrane permeability does not result in DNA fragmentation and thus must be considered as independent parameters of sperm quality.

Research paper thumbnail of Sperm deoxyribonucleic acid fragmentation dynamics in fertile donors

Fertility and Sterility, 2009

Objective: To study the velocity of sperm DNA fragmentation in frozen-thawed sperm samples from m... more Objective: To study the velocity of sperm DNA fragmentation in frozen-thawed sperm samples from male sperm donors of proved fertility. Design: Sperm DNA fragmentation assessment with use of sperm chromatin dispersion methodology after 0, 4, 8, and 24 hours of incubation in IVF medium. Setting: Academic biology and reproductive medicine centers. Patient(s): Twenty male fertility donors with proved fertility for a maximum of six births at the reproductive medicine center. Intervention(s): None. Main Outcome Measure(s): The velocity of sperm DNA fragmentation between two consecutive incubations was scored. Best adjustment of sperm DNA fragmentation index versus incubation time for linear, logarithmic, or exponential function was tested. Result(s): Increase of sperm DNA fragmentation through time accounted for a substantial percentage of the overall variation. The highest velocity of sperm DNA fragmentation was observed in the first 4 hours of incubation, decreasing by 50% during the second incubation period and being of the order of 1% in the final experimental period. The tendency to increase in sperm DNA fragmentation is not homogeneous among donors; they may adjust to a logarithmic, linear, or exponential function rendering high values for R 2. Conclusion(s): Sperm DNA fragmentation occurs rapidly after thawing, and it is an important cause of the rapid decline of sperm quality. Thus, the use of sperm samples as quickly as possible after thawing is highly recommended in clinical practice. Different sperm DNA fragmentation dynamics among individuals were observed. (Fertil Steril Ò 2009;92:170-3. Ó2009 by American Society for Reproductive Medicine.

Research paper thumbnail of Can DNA fragmentation of neat or swim-up spermatozoa be used to predict pregnancy following ICSI of fertile oocyte donors?

Asian Journal of Andrology, 2013

This study compared the potential of assessing sperm DNA fragmentation (SDF) from neat semen and ... more This study compared the potential of assessing sperm DNA fragmentation (SDF) from neat semen and the subsequent swim-up (SU) procedure to predict pregnancy when conducting ICSI of fertile donor oocytes. Infertile females (n581) were transferred embryos resulting from intracytoplasmic sperm injection (ICSI) of their partner's spermatozoa and proven donor oocytes. This model normalized the impact of female factor in putative sperm DNA repair. Semen was blindly assessed for SDF using Halosperm immediately following ejaculation (NS) and after swim-up at the time of ICSI fertilisation. There was a decrease in SDF values of the ejaculated semen sample following the swim-up protocol (P50.000). Interestingly, pregnancy could be equally predicted from SDF values derived from either neat or swim-up semen samples. Receiver operator curves and the derived Youden's indices determined SDF cutoff values for NS and SU of 24.8% and 17.5%, respectively. Prediction of pregnancy from NS SDF had a sensitivity of 75% and a specificity of 69%, whereas for SU SDF was 78% and 73%, respectively. While increased levels of SDF negatively impact reproductive outcome, we have shown that a reduction in SDF following sperm selection using ICSI with proven donor oocytes is not mandatory for achieving pregnancy. This suggests that a certain level of DNA damage that is not detectable using current technologies could be impacting on the relative success of assisted reproductive technology (ART) procedures. Consequently, we propose a modification of the so called 'iceberg model' as a possible rationale for understanding the role of SDF in reproductive outcome.

Research paper thumbnail of Oxidative stress in follicular fluid of young women with low response compared with fertile oocyte donors

Reproductive BioMedicine Online, 2016

Madrid, where she received her PhD in 1991. She has worked in the area of reproductive technologi... more Madrid, where she received her PhD in 1991. She has worked in the area of reproductive technologies since 1985 and performed a post-doctoral fellowship at the Centre for Research on Reproduction and Women's Health, Philadelphia, USA. Dr Nunez-Calonge has published numerous articles and chapters in scientific journals and books and is referee for a number of Spanish scientific journals. Her primary areas of research are embryology and male infertility.

Research paper thumbnail of ¿A qué velocidad «muere» el ácido desoxirribonucleico del espermatozoide tras descongelar muestras seminales procedentes de donantes?

Revista Internacional de Andrología, 2013

ABSTRACT Objective The study was made to analyze the baseline levels of damage recorded in sperm ... more ABSTRACT Objective The study was made to analyze the baseline levels of damage recorded in sperm DNA fragmentation (SDF) and to estimate sperm DNA longevity as observed in donors after thawing. Material and methods Fifty donors and forty individuals attending a clinic and classified as a normo-zoospermic population were compared. The baseline SDF levels and the increasing rate of SDF (r-SDF) obtained after thawing when the sperm was incubated for a period of 24 h with different sub-sampling performed after 2, 6 and 24 h of incubation were considered as the independent variables and compared. Results Cryopreserved donor sperm exhibited baseline SDF values approximately 2 times lower than those observed in the control group. DNA stability was 2.5 times higher than that observed in the control cohort. Baseline values of SDF of approximately 8% generates 65% sensitivity and 82% specificity to discriminate between the donors and controls. Values of increase of damage of 1.8% per hour, analyzed during the first hours of incubation, identify the donor characteristics with 77% sensibility and 65% specificity. Neither value show any correlation within the control and donor cohorts group. Conclusion The establishment of these types of threshold values can be used to identify donors considered as “super-donors” in relation to their low levels of SDF and high chromatin stability. The donors selected from the different clinics participating in this study showed similar characteristics for these parameters.

Research paper thumbnail of PP-09 Dynamic Analysis of Dna Fragmentation in Fresh Versus Frozen-Thawed Human Spermatozoa

Reproductive BioMedicine Online, 2010

Research paper thumbnail of Antiphospholipid Autoantibodies in Women with Recurrent Gestational Failures – Controversies in Management

Antiphospholipid Syndrome, 2012

Research paper thumbnail of Dynamics of Sperm Dna Fragmentation in Dynamics of Sperm Dna Fragmentation in Fresh and Frozen Human Semen Fresh and Frozen Human Semen

Sperm DNA fragmentation (SDF) must be considered as a dynamic process, i.e. SDF change through ti... more Sperm DNA fragmentation (SDF) must be considered as a dynamic process, i.e. SDF change through time after ejaculation. To analyse the incidence of this phenomenon on sperm quality, the dynamics of SDF was assessed in semen samples before and after freezing. Fifteen donors were included in the analysis and from the same ejaculate three aliquots were obtained. One of them was kept fresh in the seminal plasma and two were frozen-thawed. After thawing one aliquot was maintained in the freezing media and the other capacitated. For analyzing SDF all samples were processed with Halosperm (Halotech DNA SL, Madrid, Spain). Sperm from different aliquots were incubated during a period of 72 hours art 37oC and the rate of SDF at different incubation times (from 0 to 72h) were scored. Results show that the dynamic behaviour of the SDF before and after freezing are different and, in general, after thawing selection of a specific sperm subpopulation, which show less variance in the distribution of SDF values than in fresh samples, was observed. These results indicate that both the management and specially frozen thawing selection of human sperm, for use in assisted reproduction techniques, must be completed quickly in order to minimize the DNA damage. Theoretically, this practice should result in an improvement in pregnancy rates.

Research paper thumbnail of DNA Fragmentation Dynamics in Fresh Versus Frozen Thawed Plus Gradient-Isolated Human Spermatozoa

Systems Biology in Reproductive Medicine, 2010

The aim of this study was to compare the rate of sperm DNA fragmentation (rSDF; increase of SDF o... more The aim of this study was to compare the rate of sperm DNA fragmentation (rSDF; increase of SDF over time) in fresh and gradient isolated frozen-thawed semen samples from male sperm donors of proven fertility. SDF was assessed in the two samples obtained from the same fifteen male donors after 0.5, 1.5, 4.5, 6, 24, 48, and 72 h of incubation in a humidified atmosphere of 5% CO 2 in air at 371C. Analysis was performed based on chromatin dispersion patterns evaluated using the Halosperms kit. No significant differences in SDF were obtained when fresh and gradient-isolated frozen-thawed spermatozoa were compared at baseline. However, the rSDF shown by the two samples differed and gradient-isolation selected for sperm subpopulations showing a lower variance for SDF. At the individual level, sperm selection by density gradient purification in frozen-thawed samples did not improve the levels of SDF when compared with the values obtained in fresh samples at baseline.

Research paper thumbnail of Characterization of sperm DNA damage in Kartagener’s syndrome with recurrent fertilization failure: Case revisited

Sexual & Reproductive Healthcare, 2010

Single-and double-strand sperm DNA breaks was assessed in a Kartagener's syndrome with four failu... more Single-and double-strand sperm DNA breaks was assessed in a Kartagener's syndrome with four failures of fertilization after ISCI in TESA samples. It is concluded that in addition to failure of sperm motility, this patient was infertile because a high level of non-reparable sperm DNA damage was present. Although four cycles of insemination were performed at patient's request, if the argument of an exacerbated level of sperm DNA damage could be used at the time of the medical advice, repeated failed cycles of insemination using ICSI could be avoided. Pregnancy was achieved with a semen donor.

Research paper thumbnail of PP-06 Increased Fertilization Rates After In-Vitro Culture of Frozen Thawed Testicular Immotile Sperm in Non-Obstructive Azoospermic Patients

Reproductive BioMedicine Online, 2010

Research paper thumbnail of PP-37 Improvement of Ivf Outcome by Optimizing the Quality of Laboratory Performance

Reproductive BioMedicine Online, 2012

Research paper thumbnail of PP-8 Evaluation of Sperm Selection Procedure Based on Hyaluronic Acid Binding Ability on the Ivf Success of Donated Oocytes Following Icsi

Reproductive BioMedicine Online, 2012

Research paper thumbnail of OP-1 Intra-Individual Variations in Sperm Dna Fragmentation in Men from Infertile Couples Compared with Fertile Sperm Donors

Reproductive BioMedicine Online, 2012

ABSTRACT Background and Aim: Sperm DNA integrity (SDI) is an important factor in the prognosis of... more ABSTRACT Background and Aim: Sperm DNA integrity (SDI) is an important factor in the prognosis of male fertility. However, it has been noted that SDI can fluctuate over time within certain individuals. The aim of this study was to analyze and compare both within-and between-subject sperm DNA fragmentation (SDF) fluctuations in men presenting to an infertility clinic for semen analysis and in fertile sperm donors. Method: Semen specimens were collected from 51 patients (PS) and from 8 healthy sperm donors (DS). Between 2 and 6 SDF measurements per patient were performed. Fertile donors provided 49 semen samples over a period of 4 months. All samples were divided into three groups, according to the first SDF value: SDF > 30%, SDF >20% <30% and SDF < 20%. Coefficient of variation (CV) for sperm chromatin dispersion (SCD) was calculated using the formula (SD/mean)×100%.

Research paper thumbnail of Defining risk for recurrent gestational failure by blood natural killer cells subsets

Journal of Reproductive Immunology, 2012

Research paper thumbnail of A dynamic assessment of sperm DNA fragmentation versus sperm viability in proven fertile human donors

Fertility and Sterility, 2009

Objective: To analyze any possible dynamic correlation between sperm DNA fragmentation and sperm ... more Objective: To analyze any possible dynamic correlation between sperm DNA fragmentation and sperm viability. Design: The rate of viability loss and the rate of increase of the frequency of sperm cells with fragmented DNA were determined at 0, 1.5, 4.5, and 24.0 hours after thawing samples from donors with proven fertility. Setting: Academic biology and reproductive medicine centers. Patient(s): Fifteen male donors with proven fertility for a maximum of six births at the reproductive medicine center. Intervention(s): None. Main Outcome Measure(s): Sperm DNA fragmentation and viability dynamics expressed as logarithmic coefficients of change. Result(s): The dynamics of sperm DNA fragmentation and sperm viability adjusted to a logarithmic function with an initial highest velocity that progressively decreases. Nevertheless, the rates were not statistically significantly correlated. Conclusion(s): In the short term, dynamic dysfunction of membrane permeability does not result in DNA fragmentation and thus must be considered as independent parameters of sperm quality.

Research paper thumbnail of Sperm deoxyribonucleic acid fragmentation dynamics in fertile donors

Fertility and Sterility, 2009

Objective: To study the velocity of sperm DNA fragmentation in frozen-thawed sperm samples from m... more Objective: To study the velocity of sperm DNA fragmentation in frozen-thawed sperm samples from male sperm donors of proved fertility. Design: Sperm DNA fragmentation assessment with use of sperm chromatin dispersion methodology after 0, 4, 8, and 24 hours of incubation in IVF medium. Setting: Academic biology and reproductive medicine centers. Patient(s): Twenty male fertility donors with proved fertility for a maximum of six births at the reproductive medicine center. Intervention(s): None. Main Outcome Measure(s): The velocity of sperm DNA fragmentation between two consecutive incubations was scored. Best adjustment of sperm DNA fragmentation index versus incubation time for linear, logarithmic, or exponential function was tested. Result(s): Increase of sperm DNA fragmentation through time accounted for a substantial percentage of the overall variation. The highest velocity of sperm DNA fragmentation was observed in the first 4 hours of incubation, decreasing by 50% during the second incubation period and being of the order of 1% in the final experimental period. The tendency to increase in sperm DNA fragmentation is not homogeneous among donors; they may adjust to a logarithmic, linear, or exponential function rendering high values for R 2. Conclusion(s): Sperm DNA fragmentation occurs rapidly after thawing, and it is an important cause of the rapid decline of sperm quality. Thus, the use of sperm samples as quickly as possible after thawing is highly recommended in clinical practice. Different sperm DNA fragmentation dynamics among individuals were observed. (Fertil Steril Ò 2009;92:170-3. Ó2009 by American Society for Reproductive Medicine.

Research paper thumbnail of Can DNA fragmentation of neat or swim-up spermatozoa be used to predict pregnancy following ICSI of fertile oocyte donors?

Asian Journal of Andrology, 2013

This study compared the potential of assessing sperm DNA fragmentation (SDF) from neat semen and ... more This study compared the potential of assessing sperm DNA fragmentation (SDF) from neat semen and the subsequent swim-up (SU) procedure to predict pregnancy when conducting ICSI of fertile donor oocytes. Infertile females (n581) were transferred embryos resulting from intracytoplasmic sperm injection (ICSI) of their partner's spermatozoa and proven donor oocytes. This model normalized the impact of female factor in putative sperm DNA repair. Semen was blindly assessed for SDF using Halosperm immediately following ejaculation (NS) and after swim-up at the time of ICSI fertilisation. There was a decrease in SDF values of the ejaculated semen sample following the swim-up protocol (P50.000). Interestingly, pregnancy could be equally predicted from SDF values derived from either neat or swim-up semen samples. Receiver operator curves and the derived Youden's indices determined SDF cutoff values for NS and SU of 24.8% and 17.5%, respectively. Prediction of pregnancy from NS SDF had a sensitivity of 75% and a specificity of 69%, whereas for SU SDF was 78% and 73%, respectively. While increased levels of SDF negatively impact reproductive outcome, we have shown that a reduction in SDF following sperm selection using ICSI with proven donor oocytes is not mandatory for achieving pregnancy. This suggests that a certain level of DNA damage that is not detectable using current technologies could be impacting on the relative success of assisted reproductive technology (ART) procedures. Consequently, we propose a modification of the so called 'iceberg model' as a possible rationale for understanding the role of SDF in reproductive outcome.