J. Hernandez-Medrano - Academia.edu (original) (raw)

Papers by J. Hernandez-Medrano

Endocrinology, 2003

Please cite this article as: Micke GC, Sullivan TM, Kennaway DJ, Hernandez-Medrano J, Perry VEA, ... more Please cite this article as: Micke GC, Sullivan TM, Kennaway DJ, Hernandez-Medrano J, Perry VEA, Maternal endocrine adaptation throughout pregnancy to nutrient manipulation: consequences for sexually dimorphic programming of thyroid hormones and development of their progeny, Theriogenology (2014),

Journal of Animal Science, 2016

Animal Reproduction, 2016

Human Reproduction, 2014

study question: Is it possible to restore ovarian function and natural fertility following the cr... more study question: Is it possible to restore ovarian function and natural fertility following the cryopreservation and autotransplantation of whole ovaries, complete with vascular pedicle, in adult females from a large monovulatory animal model species (i.e. sheep)?

Theriogenology, 2015

Please cite this article as: Micke GC, Sullivan TM, Kennaway DJ, Hernandez-Medrano J, Perry VEA, ... more Please cite this article as: Micke GC, Sullivan TM, Kennaway DJ, Hernandez-Medrano J, Perry VEA, Maternal endocrine adaptation throughout pregnancy to nutrient manipulation: consequences for sexually dimorphic programming of thyroid hormones and development of their progeny, Theriogenology (2014),

Journal of Dairy Science, 2012

The objective of this study was to quantify on-farm variation between and within cows in methane ... more The objective of this study was to quantify on-farm variation between and within cows in methane emissions measured during milking, and to determine which factors are related to this variation. Methane emission rate during milking (MERm) was recorded at milking using methane analyzers installed in automatic (robotic) milking stations for 215 cows over a period of 5 mo. Between-cow variation in MERm (mean 2.07, SD 0.629 g/min), was greater than within-cow variation and was related to variation in body weight, milk yield, parity, and week of lactation. Estimation of daily methane emissions from MERm data, using an equation derived from comparisons with respiration chamber data, produced estimates that ranged from 278 to 456 g of CH₄/d and were commensurate with values predicted from metabolizable energy requirements for observed body weight and milk yield. It is concluded that methane emissions vary considerably between dairy cows housed under commercial conditions. This variation needs to be taken into account when performing inventories or testing mitigation strategies, but it might offer opportunities for genetic selection.

Research in Veterinary Science, 2013

The aim of this study was to evaluate endocrinological and immunological effects of early postnat... more The aim of this study was to evaluate endocrinological and immunological effects of early postnatal immunisation against gonadotrophin-releasing hormone (GnRH) in heifer calves, as similar treatment in sheep provokes long-term immunocastration. Heifer calves were injected with either a construct of GnRH -bovine herpes virus 1 glycoprotein D (BHV1 gD; n = 9) or saline (n = 9) at 2, 6 and 13.5 weeks of age. Antibody (GnRH and carrier) and endocrine responses to immunisation were measured twice monthly (FSH and progesterone) or during intensive sampling regimes (LH). Early postnatal immunisation against GnRH induced a high, but variable, antibody response against both GnRH and carrier. Based on antibody responses, animals were divided into high-titre (HT, n = 5) and low-titre (LT, n = 4). Occurring mainly in HT, a further peak in anti-GnRH antibodies, stimulated independently of the carrier, was observed at 23 weeks of age, with antibody titres P10% binding for $9 weeks post-peak. Conversely immunisation had only temporary, reversible effects on reproductive function, not affecting age at puberty. We hypothesise that the newly generated antibody measured 10 weeks after the final immunisation resulted from antigenic stimulation and immunological memory cell activation to an endogenous GnRH release. This outcome offers an opportunity for further manipulation of reproductive function based on modulation of GnRH secretion and activity where long-term immunological memory may contribute to durable endocrine effects.

Reproduction in Domestic Animals, 2012

Folliculogenesis is an intricate process that involves the proliferation and differentiation of b... more Folliculogenesis is an intricate process that involves the proliferation and differentiation of both somatic and germ cells. This process depends on complex interactions between systemic factors such as both pituitary gonadotrophins and metabolic hormones and ⁄ or local factors produced by the ovarian somatic and germ cells, such as the IGF system and TGF-b superfamily members. In domestic ruminants, follicular development begins during foetal life with formation of primordial follicles from the association of germ cells and pregranulosa cells. After follicular formation, folliculogenesis begins with a primordial follicle progressing into more developed stages (i.e. primary, secondary, pre-antral and antral) in a continuous, progressive process to either ovulation or, as in most cases, to atresia. Even early stages of follicular formation and subsequent development are influenced by both internal (e.g. genotype) and ⁄ or external environmental (e.g. nutrition and season) factors. Among these external factors, nutrition is one of the most important affecting reproductive function, and this is the focus of this review, because other reviews in this issue discuss other environmental factors. A number of studies have now shown that nutrition can have both positive and negative effects on follicular growth, oestrous activity, oocyte quality, blastocyst development and pregnancy outcome. Therefore, understanding the intricate processes involved during folliculogenesis and the ways in which factors, such as nutrition, affect them is leading to new opportunities to improve pregnancy rates by influencing follicle development and oocyte quality. This review will focus on follicular development from foetal to adult stages and the influences that nutrition has during some of these developmental stages.

Reproduction, Fertility and Development, 2012

The aim of the present study was to investigate the effect of the neonatal immunisation of bull c... more The aim of the present study was to investigate the effect of the neonatal immunisation of bull calves against a novel gonadotrophin-releasing hormone (GnRH) construct, comprised of GnRH coupled to the glycoprotein D subunit of the bovine herpes virus-1 (GnRH-BHV1 gD), on endocrine status, reproductive organ development and carcass quality. Eighteen bull calves received either GnRH construct (n ¼ 9) or saline (control; n ¼ 9) at 2, 6 and 13.5 weeks of age. Blood samples were taken to determine antibody titres against GnRH, FSH and testosterone (T) concentrations and LH pulse characteristics, with testicular circumference monitored monthly. Immunisation reduced LH pulse amplitude (P , 0.05) and T concentrations (P , 0.05), particularly at the peak in anti-GnRH titres after the second booster at 16 weeks of age (P , 0.001), but not when titres fell. Despite antibody titres decreasing after 16 weeks, immunisation reduced testicular size between 16 to 57 weeks of age (P , 0.05), provoking an 8-week delay in puberty onset, defined as testicular circumference $14 cm. In conclusion, neonatal immunisation induced a significant immune response against GnRH, provoking a temporary endocrine disturbance that had a long-term effect on testicular development, delaying the onset of puberty. These results support the hypothesis that a developmental window exists during testicular development, such that disturbance of the endocrine drive to the gonads during this period results in a longer-term impairment of gonadal function.

ABSTRACT What are the effects of exposure of ovarian tissue to dehydroepiandrosterone (DHEA) supp... more ABSTRACT What are the effects of exposure of ovarian tissue to dehydroepiandrosterone (DHEA) supplementation in vivo? DHEA exposure stimulates initiation of primordial follicles and development of gonadotrophin-responsive preantral/early antral follicles possibly mediated through promoting granulosa cell proliferation and enhancing anti-Mullerian hormone (AMH) expression. WHAT IS KNOWN ALREADY?: Ovarian ageing is a cause of subfertility and is associated with poor outcomes of IVF treatment and premature menopause. A few clinical studies have shown that DHEA can improve ovarian response and increase the chances of pregnancy after IVF treatment in women with a diminished ovarian reserve (DOR) suggesting DHEA may help to overcome the effect of ovarian ageing. However, there are no data about how DHEA acts on ovarian folliculogenesis. A cortical autograft experimental model was conducted in six female sheep aged at least 24 months. The period of DHEA treatment in the animals lasted for 10 weeks. All the animals were subjected to unilateral oophorectomy. Half of the ovary was fixed for histological analysis as a time-zero control. The remaining tissue was used to isolate patches of ovarian cortex which were autografted back onto the ovarian pedicle. The grafting procedure eradicated all growing follicles and synchronized early follicular development. After a 10-week treatment period with DHEA implants, the ewes were sacrificed and the graft and remaining ovary were harvested. Histological and immunohistochemistry (IHC) findings, accompanied with serum hormonal profiles were compared to determine the effect on the follicle population. Higher proportions of the follicle population in the remaining ovary were observed to be in the antral stage after DHEA treatment. The observation coincided with an increase in the rate of primordial follicle initiation and preantral follicle development in cortical grafts and the remaining ovarian tissue, respectively. The IHC results indicated that DHEA increased the expression of both the proliferation marker (KI-67) in granulosa cells and the follicular AMH expression at the preantral and early antral follicle stages. The experimental design compared follicle populations before and after DHEA treatment within individual animals to allow changes over time to be detected against a background of high inter-animal variation. However, since no controls without DHEA were included, we cannot say what would have happened over time in its absence, and it is possible that other factors may have resulted in the changes in follicle development observed during the experiment. Our data supports the idea that DHEA might be a useful therapy to delay the effects of ovarian ageing. Therefore, it may have a role as an adjunct during IVF to improve ovarian response in women with DOR and as a treatment for premature ovarian insufficiency. The research received finance support from the University of Nottingham. The authors declare no conflict of interest in this study.

Journal of Dairy Science, 2012

The user has requested enhancement of the downloaded file. All in-text references underlined in b... more The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately.

Endocrinology, 2003

Please cite this article as: Micke GC, Sullivan TM, Kennaway DJ, Hernandez-Medrano J, Perry VEA, ... more Please cite this article as: Micke GC, Sullivan TM, Kennaway DJ, Hernandez-Medrano J, Perry VEA, Maternal endocrine adaptation throughout pregnancy to nutrient manipulation: consequences for sexually dimorphic programming of thyroid hormones and development of their progeny, Theriogenology (2014),

Journal of Animal Science, 2016

Animal Reproduction, 2016

Human Reproduction, 2014

study question: Is it possible to restore ovarian function and natural fertility following the cr... more study question: Is it possible to restore ovarian function and natural fertility following the cryopreservation and autotransplantation of whole ovaries, complete with vascular pedicle, in adult females from a large monovulatory animal model species (i.e. sheep)?

Theriogenology, 2015

Please cite this article as: Micke GC, Sullivan TM, Kennaway DJ, Hernandez-Medrano J, Perry VEA, ... more Please cite this article as: Micke GC, Sullivan TM, Kennaway DJ, Hernandez-Medrano J, Perry VEA, Maternal endocrine adaptation throughout pregnancy to nutrient manipulation: consequences for sexually dimorphic programming of thyroid hormones and development of their progeny, Theriogenology (2014),

Journal of Dairy Science, 2012

The objective of this study was to quantify on-farm variation between and within cows in methane ... more The objective of this study was to quantify on-farm variation between and within cows in methane emissions measured during milking, and to determine which factors are related to this variation. Methane emission rate during milking (MERm) was recorded at milking using methane analyzers installed in automatic (robotic) milking stations for 215 cows over a period of 5 mo. Between-cow variation in MERm (mean 2.07, SD 0.629 g/min), was greater than within-cow variation and was related to variation in body weight, milk yield, parity, and week of lactation. Estimation of daily methane emissions from MERm data, using an equation derived from comparisons with respiration chamber data, produced estimates that ranged from 278 to 456 g of CH₄/d and were commensurate with values predicted from metabolizable energy requirements for observed body weight and milk yield. It is concluded that methane emissions vary considerably between dairy cows housed under commercial conditions. This variation needs to be taken into account when performing inventories or testing mitigation strategies, but it might offer opportunities for genetic selection.

Research in Veterinary Science, 2013

The aim of this study was to evaluate endocrinological and immunological effects of early postnat... more The aim of this study was to evaluate endocrinological and immunological effects of early postnatal immunisation against gonadotrophin-releasing hormone (GnRH) in heifer calves, as similar treatment in sheep provokes long-term immunocastration. Heifer calves were injected with either a construct of GnRH -bovine herpes virus 1 glycoprotein D (BHV1 gD; n = 9) or saline (n = 9) at 2, 6 and 13.5 weeks of age. Antibody (GnRH and carrier) and endocrine responses to immunisation were measured twice monthly (FSH and progesterone) or during intensive sampling regimes (LH). Early postnatal immunisation against GnRH induced a high, but variable, antibody response against both GnRH and carrier. Based on antibody responses, animals were divided into high-titre (HT, n = 5) and low-titre (LT, n = 4). Occurring mainly in HT, a further peak in anti-GnRH antibodies, stimulated independently of the carrier, was observed at 23 weeks of age, with antibody titres P10% binding for $9 weeks post-peak. Conversely immunisation had only temporary, reversible effects on reproductive function, not affecting age at puberty. We hypothesise that the newly generated antibody measured 10 weeks after the final immunisation resulted from antigenic stimulation and immunological memory cell activation to an endogenous GnRH release. This outcome offers an opportunity for further manipulation of reproductive function based on modulation of GnRH secretion and activity where long-term immunological memory may contribute to durable endocrine effects.

Reproduction in Domestic Animals, 2012

Folliculogenesis is an intricate process that involves the proliferation and differentiation of b... more Folliculogenesis is an intricate process that involves the proliferation and differentiation of both somatic and germ cells. This process depends on complex interactions between systemic factors such as both pituitary gonadotrophins and metabolic hormones and ⁄ or local factors produced by the ovarian somatic and germ cells, such as the IGF system and TGF-b superfamily members. In domestic ruminants, follicular development begins during foetal life with formation of primordial follicles from the association of germ cells and pregranulosa cells. After follicular formation, folliculogenesis begins with a primordial follicle progressing into more developed stages (i.e. primary, secondary, pre-antral and antral) in a continuous, progressive process to either ovulation or, as in most cases, to atresia. Even early stages of follicular formation and subsequent development are influenced by both internal (e.g. genotype) and ⁄ or external environmental (e.g. nutrition and season) factors. Among these external factors, nutrition is one of the most important affecting reproductive function, and this is the focus of this review, because other reviews in this issue discuss other environmental factors. A number of studies have now shown that nutrition can have both positive and negative effects on follicular growth, oestrous activity, oocyte quality, blastocyst development and pregnancy outcome. Therefore, understanding the intricate processes involved during folliculogenesis and the ways in which factors, such as nutrition, affect them is leading to new opportunities to improve pregnancy rates by influencing follicle development and oocyte quality. This review will focus on follicular development from foetal to adult stages and the influences that nutrition has during some of these developmental stages.

Reproduction, Fertility and Development, 2012

The aim of the present study was to investigate the effect of the neonatal immunisation of bull c... more The aim of the present study was to investigate the effect of the neonatal immunisation of bull calves against a novel gonadotrophin-releasing hormone (GnRH) construct, comprised of GnRH coupled to the glycoprotein D subunit of the bovine herpes virus-1 (GnRH-BHV1 gD), on endocrine status, reproductive organ development and carcass quality. Eighteen bull calves received either GnRH construct (n ¼ 9) or saline (control; n ¼ 9) at 2, 6 and 13.5 weeks of age. Blood samples were taken to determine antibody titres against GnRH, FSH and testosterone (T) concentrations and LH pulse characteristics, with testicular circumference monitored monthly. Immunisation reduced LH pulse amplitude (P , 0.05) and T concentrations (P , 0.05), particularly at the peak in anti-GnRH titres after the second booster at 16 weeks of age (P , 0.001), but not when titres fell. Despite antibody titres decreasing after 16 weeks, immunisation reduced testicular size between 16 to 57 weeks of age (P , 0.05), provoking an 8-week delay in puberty onset, defined as testicular circumference $14 cm. In conclusion, neonatal immunisation induced a significant immune response against GnRH, provoking a temporary endocrine disturbance that had a long-term effect on testicular development, delaying the onset of puberty. These results support the hypothesis that a developmental window exists during testicular development, such that disturbance of the endocrine drive to the gonads during this period results in a longer-term impairment of gonadal function.

ABSTRACT What are the effects of exposure of ovarian tissue to dehydroepiandrosterone (DHEA) supp... more ABSTRACT What are the effects of exposure of ovarian tissue to dehydroepiandrosterone (DHEA) supplementation in vivo? DHEA exposure stimulates initiation of primordial follicles and development of gonadotrophin-responsive preantral/early antral follicles possibly mediated through promoting granulosa cell proliferation and enhancing anti-Mullerian hormone (AMH) expression. WHAT IS KNOWN ALREADY?: Ovarian ageing is a cause of subfertility and is associated with poor outcomes of IVF treatment and premature menopause. A few clinical studies have shown that DHEA can improve ovarian response and increase the chances of pregnancy after IVF treatment in women with a diminished ovarian reserve (DOR) suggesting DHEA may help to overcome the effect of ovarian ageing. However, there are no data about how DHEA acts on ovarian folliculogenesis. A cortical autograft experimental model was conducted in six female sheep aged at least 24 months. The period of DHEA treatment in the animals lasted for 10 weeks. All the animals were subjected to unilateral oophorectomy. Half of the ovary was fixed for histological analysis as a time-zero control. The remaining tissue was used to isolate patches of ovarian cortex which were autografted back onto the ovarian pedicle. The grafting procedure eradicated all growing follicles and synchronized early follicular development. After a 10-week treatment period with DHEA implants, the ewes were sacrificed and the graft and remaining ovary were harvested. Histological and immunohistochemistry (IHC) findings, accompanied with serum hormonal profiles were compared to determine the effect on the follicle population. Higher proportions of the follicle population in the remaining ovary were observed to be in the antral stage after DHEA treatment. The observation coincided with an increase in the rate of primordial follicle initiation and preantral follicle development in cortical grafts and the remaining ovarian tissue, respectively. The IHC results indicated that DHEA increased the expression of both the proliferation marker (KI-67) in granulosa cells and the follicular AMH expression at the preantral and early antral follicle stages. The experimental design compared follicle populations before and after DHEA treatment within individual animals to allow changes over time to be detected against a background of high inter-animal variation. However, since no controls without DHEA were included, we cannot say what would have happened over time in its absence, and it is possible that other factors may have resulted in the changes in follicle development observed during the experiment. Our data supports the idea that DHEA might be a useful therapy to delay the effects of ovarian ageing. Therefore, it may have a role as an adjunct during IVF to improve ovarian response in women with DOR and as a treatment for premature ovarian insufficiency. The research received finance support from the University of Nottingham. The authors declare no conflict of interest in this study.

Journal of Dairy Science, 2012

The user has requested enhancement of the downloaded file. All in-text references underlined in b... more The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately.