Lawrence Reynolds

Publications (6)17.11 Total impact

• Article: Liver iron status and associated haematological parameters in relation to fetal growth and pregnancy outcome in rapidly growing adolescent sheep carrying a singleton lamb derived by embryo transfer.

  Justin Luther, Raymond Aitken, John Milne, Harry McArdle, Lorraine Gambling, Lawrence Reynolds, Dale Redmer, Jacqueline Wallace
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  ABSTRACT: Maternal and fetal liver iron concentrations and associated haematology parameters were determined in an adolescent sheep paradigm characterised by rapid maternal growth, premature delivery and feto-placental growth restriction. Singleton-bearing dams were offered a control or high dietary intake to induce normal or growth-restricted pregnancies, respectively. Pregnancies were terminated on Day 90 or 130 of gestation or progressed to term. Relative blood volume increased (P < 0.05) and liver iron concentration decreased (P < 0.003) from mid to late gestation in control, but not in high-intake dams. At 90 and 130 days gestation, liver iron concentrations were reduced (P < 0.001) in high-intake dams but fetal liver iron was independent of dam nutrition. High intakes leading to poor pregnancy outcome at term were characterised by increased maternal haematocrit, haemoglobin, total plasma protein, albumin (all P < 0.001) and serum iron (P < 0.05), and by reduced oestradiol 17β (P < 0.001) at Day 130. Thus, high dietary intakes that promote rapid maternal growth and adiposity are associated with early depletion of maternal liver iron stores and a relative failure of normal blood volume expansion, which may, in turn, underlie the reduction in uteroplacental blood flows and fetal nutrient delivery previously established for this paradigm.
  Reproduction Fertility and Development 10/2010; 22(8):1230-6. · 2.11 Impact Factor
• Source

  Available from: Justin Luther

  Article: Uteroplacental vascular development and placental function: an update.

  Lawrence P Reynolds, Pawel P Borowicz, Joel S Caton, Kimberly A Vonnahme, Justin S Luther, David S Buchanan, Shireen A Hafez, Anna T Grazul-Bilska, Dale A Redmer
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  ABSTRACT: The importance of the placenta and its vascular development to fetal growth and development has been appreciated since ancient times. Based on numerous studies in humans and animal model organisms in the last 2-3 decades, normal placental angiogenesis is critically important to ensure adequate blood flow to the placenta and therefore to provide the substrates that support normal fetal growth. Placental angiogenesis is abnormal at term in compromised pregnancies (those in which fetal growth is altered), including those resulting from maternal nutritional or environmental stress, maternal age, increased numbers of fetuses, maternal or fetal genotype, or the use of assisted reproductive technologies (e.g., cloning by somatic cell nuclear transfer). We and others have recently shown that these defects in placental vascular development occur quite early in pregnancy and may therefore presage compromised fetal growth and development. The challenges will be to find biomarkers of abnormal placental angiogenesis and to develop therapeutic strategies to "rescue" placental vascular development and thus fetal growth in compromised pregnancies. Animal models will be essential in meeting these challenges.
  The International journal of developmental biology 11/2009; 54(2-3):355-66. · 2.16 Impact Factor
• Source

  Available from: ehu.es

  Article: Some historical aspects of understanding placental development, structure and function.

  Lawrence D Longo, Lawrence P Reynolds
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  ABSTRACT: Ideas concerning the placenta, its development, structure and function can be traced to antiquity. An issue of importance that was only resolved in the late-eighteenth to early-nineteenth century is that of the separate nature of the maternal and fetal placental circulations. Other vital issues include the placentas of twins, the structure of placental villi and their covering, the classification of placental types, the existence of the intervillous space, and the relation of maternal to fetal blood flows in the placenta. Contemporary challenges in placental biology include understanding the basic mechanisms of numerous aspects of metabolism, endocrinology, immunology, epigenetics, and the role of specific placental proteins in embryonic/fetal development.
  The International journal of developmental biology 10/2009; 54(2-3):237-55. · 2.16 Impact Factor
• Article: Placental growth, angiogenic gene expression, and vascular development in undernourished adolescent sheep.

  Justin Luther, John Milne, Raymond Aitken, Masatoshi Matsuzaki, Lawrence Reynolds, Dale Redmer, Jacqueline Wallace
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  ABSTRACT: Limiting maternal nutrient intake during ovine adolescent pregnancy progressively depleted maternal body reserves, impaired fetal nutrient supply, and slowed fetal soft tissue growth. The present study examined placental growth, angiogenic gene expression, and vascular development in this undernourished adolescent model at Days 90 and 130 of gestation. Singleton pregnancies were established, and ewes were offered an optimal control (C; n = 14) or low (L [0.7 x C]; n = 21) dietary intake. Seven ewes receiving L intakes were switched to C intakes on Day 90 of gestation (L-C). Fetal body weight (P < 0.01) and glucose concentrations (P < 0.03) were reduced in L versus C pregnancies by Day 130, whereas L-C group values were intermediate. Placental cellular proliferation, gross morphology, and mass were independent of maternal nutrition at both Day 90 and 130. In contrast, capillary area density in the maternal caruncular portion of the placentome was reduced by 20% (P < 0.001) at both stages of gestation in L compared with C groups. Caruncular capillary area density was equivalent in the L and L-C groups at Day 130. Placental mRNA expression of five key angiogenic ligands or receptors increased (P < 0.001) between Days 90 and 130 of gestation. VEGFA mRNA expression was higher (P < 0.04) in L compared with C and L-C pregnancies at Day 130, but otherwise gene expression of the remaining angiogenic factors and receptors analyzed was unaffected by maternal intake. Undernourishing the pregnant adolescent dam restricts fetal growth independently of changes in placental mass. Alterations in maternal placental vascular development may, however, play a role in mediating the previously reported reduction in maternal and hence fetal nutrient supply.
  Biology of Reproduction 09/2007; 77(2):351-7. · 4.01 Impact Factor
• Article: Maternal and fetal growth, body composition, endocrinology, and metabolic status in undernourished adolescent sheep.

  Justin Luther, Raymond Aitken, John Milne, Masatoshi Matsuzaki, Lawrence Reynolds, Dale Redmer, Jacqueline Wallace
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  ABSTRACT: The influence of relative maternal undernutrition on growth, endocrinology, and metabolic status in the adolescent ewe and her fetus were investigated at Days 90 and 130 of gestation. Singleton pregnancies to a single sire were established, and thereafter ewes were offered an optimal control (C; n = 14) or low (L [0.7 x C]; n = 21) dietary intake. Seven ewes receiving the L intake were switched to the C intake on Day 90 of gestation (L-C). At Day 90, live weight and adiposity score were reduced (P < 0.001) in L versus C dams. Plasma insulin and IGF1 concentrations were decreased (P < 0.02), whereas glucose concentrations were preserved in L relative to C intake dams. Fetal and placental mass was independent of maternal nutrition at this stage. By Day 130 of gestation, when compared to C and L-C dams, maternal adiposity was further depleted in L intake dams; concentrations of insulin, IGF1, and glucose were reduced; and nonesterified fatty acids increased. At Day 130, placental mass remained independent of maternal nutrition, but body weight was reduced (P < 0.01) in L compared with C fetuses (3555 g vs. 4273 g). Body weight was intermediate (3836 g) in L-C fetuses. Plasma glucose (P < 0.03), insulin (P < 0.07), and total liver glycogen content (P < 0.04) were attenuated in L fetuses. Fetal carcass analyses revealed absolute reductions (P < 0.05) in dry matter, crude protein, and fat, and a relative (g/kg) increase in carcass ash (P < 0.01) in L compared with C fetuses. Thus, limiting maternal intake during adolescent pregnancy gradually depleted maternal body reserves, impaired fetal nutrient supply, and slowed fetal soft tissue growth.
  Biology of Reproduction 09/2007; 77(2):343-50. · 4.01 Impact Factor
• Source

  Available from: boar.or.kr

  Article: Development of sheep androgenetic embryos is boosted following transfer of male pronuclei into androgenetic hemizygotes.

  Kazutsugu Matsukawa, Margherita Yayoi Turco, Pier Augusto Scapolo, Lawrence Reynolds, Grazyna Ptak, Pasqualino Loi
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  ABSTRACT: Androgenetic embryos are useful model for investigating the contribution of the paternal genome to embryonic development. Little work has been done with androgenetic embryo production in domestic animals. The aim of this study was the production of diploid androgenetic sheep embryos. In vitro matured sheep oocytes were enucleated and fertilized in vitro; parthenogenetic and normally fertilized embryos were also produced as a control. Fifteen hours after in vitro fertilization (IVF), presumptive zygotes were centrifuged and scored for the number of pronucleus. IVF, parthenogenetic, and androgenetic embryos (haploid, diploid, and triploid) were cultured in SOFaa medium with bovine serum albumin (BSA). The proportion of oocytes with polyspermic fertilization increased linearly with increasing sperm concentration. After IVF, there was no significant difference in early cleavage and morula formation rates between the groups, while there was a significant difference on blastocyst development between IVF, parthenogenetic, and androgenetic embryos, the last ones displaying poor developmental potential (IVF, parthenogenetic, and haploid, diploid, and triploid androgenetic embryos: 43%, 38%, 0%, 2%, and 2%, respectively). In order to boost androgenetic embryonic development, we produced diploid androgenetic embryos through pronuclear transfer. Single pronuclei were aspirated with a bevelled pipette from haploid or diploid embryos and transferred into the perivitelline space of other haploid embryos, and the zygotes were reconstructed by electrofusion. Fusion rates approached 100%. Pronuclear transfer significantly increased blastocyst development (IVF, parthenogenetic, androgenetic: Diploid into Haploid, and Haploid into Haploid: 42%, 42%, 19%, and 3%, respectively); intriguingly, the Haploid + Diploid group showed the highest development to blastocyst stage. The main findings of our study are: (1) sheep androgenetic embryos display poor developmental ability compared with IVF and parthenogenetic embryos; (2) diploid androgenetic embryos produced by pronuclear exchange developed in higher proportion to blastocyst stage, particularly in the Diploid-Haploid group. In conclusion, pronuclear transfer is an effective method to produce sheep androgenetic blastocysts.
  Cloning and Stem Cells 02/2007; 9(3):374-81. · 2.66 Impact Factor