Publications by authors named "JA Owens"

Epidemiological studies suggest that retarded growth before birth is associated with increased plasma total and low-density lipoprotein (LDL) cholesterol concentrations in adult life. Thus perturbations of prenatal growth may permanently alter cholesterol metabolism. To determine directly whether restriction of prenatal nutrition and growth alters postnatal cholesterol homeostasis, the plasma cholesterol response to cholesterol feeding (0.

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Developmental features of sleep.

Child Adolesc Psychiatr Clin N Am

October 1999

In sum, sleep disorders are common problems for children and adolescents, with estimates indicating that approximately 20% to 25% of the pediatric population experiences some type of sleep disturbance. Furthermore, clinicians should be aware that sleep disturbances may not only exist in isolation, but can be related to psychiatric or medical issues. Although much appears to be known about sleep disorders in the pediatric population, our knowledge of this area is still in its infancy.

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1. We have measured arterial blood pressure between 115 and 145 days gestation in normally grown fetal sheep (control group; n = 16) and in fetal sheep in which growth was restricted by experimental restriction of placental growth and development (PR group; n = 13). There was no significant difference in the mean gestational arterial blood pressure between the PR (42.

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We have investigated the effects of increasing gestational age, maternal undernutrition or restricted placental growth on prolactin receptor (PRLR) gene expression in perirenal adipose tissue collected from foetal sheep during late gestation (term = 147 d +/- 3 d of gestation). Foetal nutrient supply was reduced by either restriction of placental growth following removal of endometrial caruncles before mating or by reducing maternal feed intake by 50% from 115 d of gestation. Total RNA was extracted from adipose tissue taken from foetal sheep between 90 and 145 d of gestation, and only at 141-145 d in placentally restricted, nutrient restricted and control foetuses.

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The aims of this study were to determine whether placental restriction (PR) alters the pattern of localization of the catecholamine-synthesizing enzymes, dopamine-beta-hydroxylase and phenylethanolamine N-methyltransferase, and enkephalin (ENK)-containing peptides in the adrenal gland of the midgestation sheep fetus. We also determined the effect of PR on the content and profile of the molecular mass forms of ENK-containing peptides in the fetal adrenal medulla. Placental growth was restricted by removal of most of the placental implantation sites in the uterus before mating.

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The effect of fasting (17-18 h) versus food restriction (70% for 80 +/- 13 days) on the IGF-IGF binding protein (BP) axis in female guinea pigs was studied and related to body weight, weight gain and food conversion efficiency. Circulating IGF-I was reduced in the fasted (13%) and food-restricted (50%) animals. IGF-II was only decreased (61%) in the food-restricted group.

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The effect of moderate food restriction on pregnancy-associated changes in weight gain, body composition, and circulating insulin-like growth factors (IGF) I and II and IGF-binding proteins (IGFBP)-1 through-4 and their relationship was determined in the guinea pig. Pregnancy did not stimulate weight gain but reduced fat deposition in ad libitum-fed animals and increased weight gain and fat deposition in food-restricted animals relative to their respective virginal group. Pregnancy increased the abundance of circulating IGF-I regardless of food intake and increased that of IGF-II in food-restricted animals only.

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We have characterized the localization and the ontogenetic changes in Neuropeptide tyrosine (NPY) before birth and investigated the regulation of NPY expression by cortisol and undernutrition in the fetal sheep hypothalamus during late gestation. Using immunohistochemistry, we have identified NPY-containing neurons in the infundibular nucleus and the internal layer of the median eminence in fetal hypothalami collected between 110 and 147 days gestation. NPY projections were also present in the paraventricular nucleus (PVN) of fetal hypothalami at all ages between 110 days gestation and term.

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Growth of the placenta is influenced by events before and during early pregnancy. Some of these events set the growth trajectory of the placenta and the fetus for the remainder of the pregnancy. Maternal size and nutrition, and the local metabolic, cytokine and hormonal environment of the embryo all affect growth of the placenta.

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We have investigated the impact of chronic restriction of placental function on circulating catecholamine concentrations and responses to the indirectly acting, sympathomimetic amine, tyramine, in the fetal sheep in late gestation. In 10 ewes, endometrial caruncles or placental placentation sites were removed before conception (placental restriction (PR) group). Fetal sheep in the PR group were hypoxemic throughout late gestation and growth-restricted (3.

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We have investigated the effects of a 5 day infusion of cortisol into fetal sheep, in which the hypothalamus and pituitary were surgically disconnected (HPD), on fetal pituitary-adrenal function. Fetal HPD and vascular catheterization were carried out at between 104 and 124 days gestation. Cortisol was administered (3.

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This study examined the effects of reduced nutrition on fetal growth over the first half of gestation. Reduced nutrition was achieved by a combination of reduced maternal food intake and carunclectomy, a procedure which restricts the development of the placenta. There were no major effects of restriction on fetal body, tissue or organ growth, except for the gastrointestinal tract (GIT).

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Liver contains the highest concentrations of insulin-like growth factor (IGF) I mRNA in adult rats and sheep and is a major source of circulating IGF-I. In rats, inhibition of hepatic IGF-I production by exogenous IGF-I has been reported. In fetal sheep, skeletal muscle and liver are major sites of IGF-I synthesis and potential sources of circulating IGF-I.

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We have experimentally restricted placental growth in the sheep to investigate the impact of reduced substrate delivery on fetal pituitary proopiomelanocortin (POMC) mRNA levels and on circulating ACTH 1-39, immunoreactive ACTH, and cortisol concentrations during late gestation. Endometrial caruncles were removed in nine ewes before mating to reduce the number of placentomes formed [placental restriction group (PR)]. Fetal arterial PO2 and O2 saturation were reduced in the PR group (2.

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Empirical evidence suggests that between 33% and 83% of Hawaii women receiving services from programs that serve battered women meet diagnostic criteria for posttraumatic stress disorder (PTSD). In addition, PTSD symptom severity is associated with depression severity, lowered self-esteem, and diminished quality of life. Combined with evidence that domestic violence often goes on for years, these findings provide additional compelling reasons why domestic violence screening should be conducted routinely in medical settings.

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Insulin-like growth factor I (IGF-I) is required for normal fetal growth and skeletal maturation in late gestation, because null mutations of the IGF-I gene in mice reduce fetal weight and retard ossification of bones. To determine if, conversely, increased abundance of IGF-I promotes fetal growth and skeletal maturation, fetal sheep were infused intravascularly with recombinant human IGF-I (n = 7) (26 +/- 3 micrograms. h-1.

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The effects of cortisol on hepatic GH receptor and insulin-like growth factor-I (IGF-I) gene expression were investigated in sheep fetuses during late gestation and after experimental manipulation of plasma cortisol levels by fetal adrenalectomy and exogenous infusion of cortisol. Hepatic GH receptor and IGF-I messenger RNA (mRNA) levels increased with increasing gestational age in parallel with the normal rise in fetal cortisol levels toward term (145 +/- 2 days). These increases in mRNA abundance toward term were prevented when the prepartum cortisol surge was abolished by fetal adrenalectomy and were stimulated prematurely in fetuses younger than 130 days by exogenous infusion of cortisol.

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The effects of recombinant bovine GH (rbGH) treatment on the insulin-like growth factor (IGF) axis and protein metabolism during fasting induced metabolic stress were evaluated in young lambs. To explore whether rbGH pretreatment alone might offer a degree of protection against nutritional stress, we compared the effects of rbGH given only before or during the fasting-induced metabolic stress with that given over the whole period. The animals were fed ad libitum for 5 days (well fed phase) and then fasted for 70 h (fasted phase).

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1. We have investigated the role of the fetal hypothalamo-pituitary axis in the control of adrenocortical growth and steroidogenesis in the sheep fetus during late gestation. Plasma concentrations of ACTH(1-39) increased between 120-125 and 136-142 days (P < 0.

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To determine whether tissue production of the IGFs is altered when fetal growth is retarded, IGF-I and -II mRNAs were measured in tissues of fetal sheep subjected to placental restriction and the relationships between IGF gene expression, circulating IGF protein and fetal growth were examined. The majority of potential placental attachment sites were surgically removed from the uterus of 12 non-pregnant ewes to restrict placental size in a subsequent pregnancy. Blood and tissues were collected at 121 days of gestation (term = 150) in 12 fetuses with restricted placental size and eight normal fetuses.

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The insulin-like growth factors (IGFs) are important regulators of growth and development in eutherian mammals. In this study we have analyzed circulating insulin-like growth factor binding proteins (IGFBPs) by Western ligand blotting (WLB) and neutral gel filtration, and hepatic IGFBP mRNA transcripts in the wallaby, Macropus eugenii, a marsupial in which the fetus is born at an immature stage compared to eutherian mammals. Plasma from male and female adults, lactating mothers, and pouch young contains an IGF binding species consisting of a 42- to 50-kDa doublet, 30, 28, 24, and approximately 200 kDa, as shown by WLB.

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The IGF-binding proteins (IGFBPs) are a family of at least six structurally related proteins, which bind the IGFs and modulate their actions, including the regulation of pre- and postnatal growth. In this study we have examined the relationship between circulating and tissue mRNA levels of IGFBPs and related this to circulating IGFs in the fetal sheep over the gestational period when rapid growth and development occurs. Circulating IGFBP-2, as measured by Western ligand blot (WLB), increases between early and mid gestation, remains high, then declines throughout late gestation (P = 0.

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It is clear that the timing of parturition is dependent on a cascade of endocrine signals from an intact fetal hypothalamo-pituitary-adrenal axis. What is not known, however is the nature or source of the central neural stimulation which results in the stimulation of adrenocorticotrophic hormone (ACTH) synthesis and secretion in late gestation. The changes which occur in the synthesis and posttranslational processing of the ACTH precursor, proopiomelanocortin (POMC), in the fetal anterior pituitary before birth and the consequence of these changes for expression of the corticosteroidogenic enzymes in the fetal adrenal are described in this review.

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