Relevant bibliographies by topics / Fetal lamb

Academic literature on the topic 'Fetal lamb'

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Published: 10 December 2022
Last updated: 29 January 2023

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Journal articles on the topic "Fetal lamb"

1

Rajion, MA, JG McLean, and R. NP Cahill. "Essential Fatty Acids in the Fetal and Newborn Lamb." Australian Journal of Biological Sciences 38, no. 1 (1985): 33. http://dx.doi.org/10.1071/bi9850033.

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The concentrations of linoleic and linolenic acids and their metabolites in the liver, kidney, brain, erythrocytes and plasma of fetal lambs at various stages of gestation, and of newborn and 2-week-01d suckled lambs was determined. Throughout gestation the fetal tissues, erythrocytes and plasma all contained low levels of linoleic and linolenic acids together with consistently high levels of their long-chain polyunsaturated metabolites. The triene : tetraene (eicosa-5,8, 11-trienoic acid/arachidonic acid) ratio was always 0 . 4 or less except at birth when it reached 0 . 6 in liver and 0 . 9 in plasma. Milk intake significantly increased the linoleic and linolenic acid levels in the lamb by 2 weeks after birth. These results show that the developing fetal lamb should not be regarded as being deficient in essential fatty acids, as suggested by previous investigators. It is proposed that the total metabolites of linoleic and linolenic acids are the most appropriate measure of the essential fatty acid status of the fetal lamb.
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Brown, Erin G., Benjamin A. Keller, Lee Lankford, Christopher D. Pivetti, Shinjiro Hirose, Diana L. Farmer, and Aijun Wang. "Age Does Matter: A Pilot Comparison of Placenta-Derived Stromal Cells for in utero Repair of Myelomeningocele Using a Lamb Model." Fetal Diagnosis and Therapy 39, no. 3 (July 7, 2015): 179–85. http://dx.doi.org/10.1159/000433427.

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Introduction: Fetal amniotic membranes (FM) have been shown to preserve spinal cord histology in the fetal sheep model of myelomeningocele (MMC). This study compares the effectiveness of placenta-derived mesenchymal stromal cells (PMSCs) from early-gestation versus term-gestation placenta to augment FM repair to improve distal motor function in a sheep model. Methods: Fetal lambs (n = 4) underwent surgical MMC creation followed by repair with FM patch with term-gestation PMSCs (n = 1), FM with early-gestation PMSCs (n = 1), FM only (n = 1), and skin closure only (n = 1). Histopathology and motor assessment was performed. Results: Histopathologic analysis demonstrated increased preservation of spinal cord architecture and large neurons in the lamb repaired with early-gestation cells compared to all others. Lambs repaired with skin closure only, FM alone, and term-gestation PMSCs exhibited extremely limited distal motor function; the lamb repaired with early-gestation PMSCs was capable of normal ambulation. Discussion: This pilot study is the first in vivo comparison of different gestational-age placenta-derived stromal cells for repair in the fetal sheep MMC model. The preservation of large neurons and markedly improved motor function in the lamb repaired with early-gestation cells suggest that early-gestation placental stromal cells may exhibit unique properties that augment in utero MMC repair to improve paralysis.
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Morin, F. C., E. A. Egan, W. Ferguson, and C. E. Lundgren. "Development of pulmonary vascular response to oxygen." American Journal of Physiology-Heart and Circulatory Physiology 254, no. 3 (March 1, 1988): H542—H546. http://dx.doi.org/10.1152/ajpheart.1988.254.3.h542.

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The ability of the pulmonary circulation of the fetal lamb to respond to a rise in oxygen tension was studied from 94 to 146 days of gestation. The unanesthetized ewe breathed room air at normal atmospheric pressure, followed by 100% oxygen at three atmospheres absolute pressure in a hyperbaric chamber. In eleven near-term lambs (132 to 146 days of gestation), fetal arterial oxygen tension (PaO2) increased from 25 +/- 1 to 55 +/- 6 Torr (mean +/- SE), which increased the proportion of right ventricular output distributed to the fetal lungs from 8 +/- 1 to 59 +/- 5%. In five very immature lambs (94 to 101 days of gestation), fetal PaO2 increased from 27 +/- 1 to 174 +/- 70 Torr, but the proportion of right ventricular output distributed to the lung did not change, 8 +/- 1 to 9 +/- 1%. In five of the near-term lambs, pulmonary blood flow was measured. It increased from 34 +/- 3 to 298 +/- 35 ml.kg fetal wt-1.min-1, an 8.8-fold increase. We conclude that the pulmonary circulation of the fetal lamb does not respond to an increase in oxygen tension before 101 days of gestation; however, near term an increase in oxygen tension alone can induce the entire increase in pulmonary blood flow that normally occurs after the onset of breathing at birth.
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Walther, F. J., R. David-Cu, E. I. Mehta, D. H. Polk, A. H. Jobe, and M. Ikegami. "Higher lung antioxidant enzyme activity persists after single dose of corticosteroids in preterm lambs." American Journal of Physiology-Lung Cellular and Molecular Physiology 271, no. 2 (August 1, 1996): L187—L191. http://dx.doi.org/10.1152/ajplung.1996.271.2.l187.

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Although administration of exogenous corticosteroids accelerates the late gestational rise in fetal rat and lamb lung antioxidant enzyme activity, the effect of dosing intervals on these responses remains uncertain. We studied the persistence and efficacy of the antioxidant response in fetal lamb lung to a single fetal dose of corticosteroids injected between 121 and 127 days gestational age. Fetal lambs received 0.5 mg/kg of betamethasone (n = 35) or saline (n = 26) by fetal intramuscular injection 24 h, 48 h, 4 days, or 7 days before preterm delivery at 128 days gestation (term = 150 days). After delivery, the lambs were ventilated for 40 min and killed. Total superoxide dismutase, catalase, glutathione peroxidase activities, and lipid hydroperoxide levels were measured, using homogenized lung. The saline-injected controls were similar at all time points. Lung antioxidant enzyme activity was consistently higher and lipid hydroperoxide presence was lower in the betamethasone-treated groups. We conclude that the positive effect of a single fetal dose of betamethasone on lung antioxidant enzyme activity occurs within 24 h after exposure, persists over a period of 7 days without a major change in the magnitude of the response, and leads to a reduction in lipid hydroperoxide formation during immediate postdelivery oxygen exposure.
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Binder, N. D., and D. F. Anderson. "Plasma renin activity responses to graded decreases in renal perfusion pressure in fetal and newborn lambs." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 262, no. 3 (March 1, 1992): R524—R529. http://dx.doi.org/10.1152/ajpregu.1992.262.3.r524.

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We examined the relationship between acute reductions in renal perfusion pressure, as approximated by femoral arterial blood pressure, and plasma renin activity in the uninephrectomized fetal lamb. Renal perfusion pressure was reduced and maintained at a constant value by controlled partial occlusion of the aorta above the renal artery. After 15 min of reduced blood pressure, blood samples were taken for determination of plasma renin activity. This protocol was performed 22 times in 11 fetal lambs. Additionally, three of the fetuses were delivered by cesarean section and studied as newborns for the first week of life. In the fetus, there was a linear relationship between log plasma renin activity and femoral arterial blood pressure (P less than 0.01). After birth, the relationship still existed, although it was shifted to the right (P less than 0.0001). We conclude that there is a significant relationship between plasma renin activity and renal perfusion pressure in the fetal lamb, and as early as 1 day after birth, this relationship shifts to the right in the newborn lamb.
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Rosenkrantz, T. S., I. Knox, E. L. Zalneraitis, J. R. Raye, P. J. Porte, R. Cramer, R. Smoloski, and A. F. Phillipps. "Cerebral metabolism and electrocortical activity in the chronically hyperglycemic fetal lamb." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 265, no. 6 (December 1, 1993): R1262—R1269. http://dx.doi.org/10.1152/ajpregu.1993.265.6.r1262.

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Previous studies in the fetal lamb have demonstrated that hyperglycemia stimulates the fetal metabolic rate. The present study examined the effects of chronic fetal hyperglycemia on fetal cerebral metabolic rate and electrocortical activity. Nine chronically instrumented fetal lambs had measurements of cerebral blood flow and cerebral uptake/excretion of oxygen, glucose, lactate, and beta-hydroxybutyrate taken before and during a 48-h fetal glucose infusion. Electrocortical activity was also recorded. The fetal arterial glucose concentration was 19.8 +/- 2.0 mg/dl before glucose infusion and 48 +/- 4.5 to 54.6 +/- 6.6 mg/dl during the infusion period. Cerebral blood flow and cerebral glucose and oxygen uptake increased by 219, 209, and 171%, respectively, by the end of the infusion period. There was a linear relationship between the fetal arterial glucose concentration and cerebral blood flow and cerebral glucose and oxygen uptakes. The electroencephalogram showed significant slowing with increases in the cerebral metabolic rate. These findings suggest that fetal hyperglycemia is associated with significant metabolic stimulation of the brain.
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Gilbert, R. D., H. Schroder, T. Kawamura, P. S. Dale, and G. G. Power. "Heat transfer pathways between fetal lamb and ewe." Journal of Applied Physiology 59, no. 2 (August 1, 1985): 634–38. http://dx.doi.org/10.1152/jappl.1985.59.2.634.

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Heat produced by the fetus exists to the mother by one of two principal routes: by fetal-maternal exchange in the placenta or through the fetal skin to the amniotic fluid and uterine wall. We measured heat conductances along each pathway to estimate the fraction of total heat exiting each route. Thermistors were placed in the fetal aorta, two different sites in the amniotic fluid, and in a maternal artery. Five days after surgery we injected a total of 280 ml of ice-cold saline into the two separate amniotic fluid sites during a 45-s interval and measured the temperature response for the next hour. After one or two such injections the fetus was killed to cut off umbilical blood flow, and the experiment was repeated to measure the heat fluxes in the absence of placental heat exchange. Experimentally obtained temperature curves were compared with the predictions of a mathematical model. Heat conductances of the skin and uterine wall, as well as the fetal heat production, were estimated in the model using least-squares parameter optimization. In 10 fetal lambs, weighing 3.73 +/- 0.40 (SE) kg, total fetal heat production averaged 3.75 +/- 0.33 W X kg-1. The heat conductance of the uterine wall, 6.6 +/- 0.8 W X degrees C-1, was lower than that of the fetal skin, 10.2 +/- 1.0, and of the placenta, 25.7 +/- 2.9 W X degrees C-1, temperature gradient. We estimated that 84.5% of total fetal heat production exists by fetal-maternal exchange in the placenta with the remaining 15.5% exiting through the fetal skin.
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Moores, R. R., B. S. Carter, G. Meschia, P. V. Fennessey, and F. C. Battaglia. "Placental and fetal serine fluxes at midgestation in the fetal lamb." American Journal of Physiology-Endocrinology and Metabolism 267, no. 1 (July 1, 1994): E150—E155. http://dx.doi.org/10.1152/ajpendo.1994.267.1.e150.

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Plasma serine disposal rate (DR), decarboxylation, and conversion to fetal plasma glycine by the placenta were measured in six fetal lambs at 72 +/- 1 days gestation. L-[1-13C]serine, L-[U-14C]serine, and 3H2O were infused over 3 h into the fetal circulation, the latter for measurement of uterine and umbilical blood flow. The fetal plasma serine DR was 8.7 +/- 1.0 mumol/min or 61.8 +/- 4 mumol.min-1.kg fetus-1. Approximately 90% of the DR represented placental uptake of fetal serine. There was no detectable release of fetal serine into the maternal circulation. The fetal arterial plasma glycine-to-serine enrichment ratio was approximately 0.30. The conversion rate of fetal serine to fetal plasma glycine by the placenta was 5.8 +/- 0.7% of the serine DR. Fetal and placental CO2 production from fetal plasma serine carbon was 1.9 +/- 0.4 and 1.2 +/- 0.4 mumol/min, respectively. Thus, at midgestation, there is a rapid fetoplacental serine exchange that constitutes most of the fetal plasma serine turnover. Placental conversion of serine to fetal glycine and serine oxidation together account for only 10% of the placental uptake of fetal serine.
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Martin, Ana Carranza, and Alejandro E. Relling. "PSXIII-33 Polyunsaturated fatty acid and their fetal programming effect on the FFARs from ewe lambs’ ovaries." Journal of Animal Science 97, Supplement_3 (December 2019): 364–65. http://dx.doi.org/10.1093/jas/skz258.728.

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Abstract Free fatty acids (FA) receptors (FFAR) are critical for metabolic functions and energy homeostasis. The FFAR1 and FFAR4 are activated by long-chain polyunsaturated FA, but FFAR2 and FFAR3 join to short-chain FA. There is no evidence fetal programming on nutritional effects on those receptors, insulin receptor (INS-R) and stereological enzyme in lambs’ ovaries. The objective of this study was to evaluate the effect of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) supplementation to ewes during late gestation on finishing lamb ovary gene expression. Lambs born from ewes supplemented with Ca salts of EPA and DHA (PUFA), or palm FA distillate (PFAD) high in palmitic and oleic acid at 0.39% DM during the last 50d of gestation were used. After weaning and high concentrate diet adaptation (45d), 14 Hampshire x Dorset cross females lambs were blocked by initial BW and used in a 2x2 factorial arrangement of treatments using the factors of dam supplementation and lamb diets (PUFA or PFAD at 1.5% DM). At day 42, lambs were euthanized and ovary samples were obtained for FFARs, INS-R and steroid acute regulatory protein (STAR) mRNA concentration analysis. There was a dam diet effect on the abundance of FFAR4 mRNA (P = 0.05); lambs born from PUFA dams showed greater concentration than PFAD. Also, PUFA lambs tend to have greater concentration of FFAR4 (P = 0.07). The abundance of FFAR2, INS-R, and STAR mRNA was not significant for dam or lamb diet effect (P > 0.1). The mRNA of FFAR1 and FFAR3 were no found in the samples. However, mRNA concentration of FFAR2 and STAR were positively associated (r = 0.74 P < 0.05). In conclusion, dam and lamb diets modified FFAR4 mRNA concentration; and there might be a functional association between FFAR2 and STAR.
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Rurak, Dan, and Natalee W. Bessette. "Changes in fetal lamb arterial blood gas and acid-base status with advancing gestation." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 304, no. 10 (May 15, 2013): R908—R916. http://dx.doi.org/10.1152/ajpregu.00430.2012.

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To determine whether there are changes in blood gas and acid-base status with advancing gestation in the fetal lamb, similar to that reported in the human fetus, blood gas, acid-base, and blood metabolite values were measured in 447 control, arterial blood samples from 108 chronically instrumented fetal lambs between 103 and 146 days gestation. With advancing gestation, Po2, pH, O2saturation, and O2content fell significantly, while Pco2and hemoglobin concentration increased. Blood glucose and lactate concentrations were unchanged, although the lactate level increased with decreasing Po2, particularly when below ∼13 mmHg. Multiple linear regression indicated that increasing fetal number was associated with decreased Po2and glucose level and increased pH, HCO3−, base excess, and lactate concentration. Hemoglobin concentration was higher in female than male lambs. Overall, there was a linear relationship between glucose concentration and birth weight. It is concluded that in fetal lambs as in the human fetus, there are changes in blood gas and acid-base status with advancing gestation. This may be due to the decrease in fetal weight-normalized uterine and umbilical blood flows than occurs in these and other species as gestation proceeds. In addition, the reduced birth weight in twin and triplet lambs may be due to hypoglycemia rather than hypoxemia.
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Dissertations / Theses on the topic "Fetal lamb"

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Vugt, Johannes Marinus Gerardus van. "Fetal artery Doppler velocimetry a study in the human fetus and the fetal lamb /." Maastricht ; Rijksuniversiteit Limburg ; Maastricht : University Library, Maastricht University [Host], 1988. http://arno.unimaas.nl/show.cgi?fid=5436.

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Shariff, Mohammed Azamatulla. "Kinetics of selenium metabolism in the ewe and fetal lamb." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/27528.

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To investigate the whole body metabolism of selenium (Se), isotope kinetic studies were undertaken in which indwelling catheters were implanted in the jugular veins of pregnant and nonpregnant ewes as well as the inferior vena cava and saphenous veins of 110-120 day (d) old ovine fetuses. A single injection of ⁷⁵Se-sodium selenite was administered and blood samples were obtained at various times. A 5 d Se balance trial, which commenced on the day of tracer experiment, was also undertaken. The plasma ⁷⁵Se specific activity data were used for determining the kinetic parameters of Se metabolism and the placental transfer rates. Using the Se balance and tracer data the net absorption and the fecal losses of Se were calculated. The fractional rate constants and T½ Se utilization in individual tissues were estimated by sacrificing the ewes and the fetuses at different times after the tracer injection and determining the tissue ⁷⁵Se specific activities. The effect of Se deficiency on the kinetics, placental transfer, net absorption and tissue metabolism was studied in a similar manner by feeding the ewes with Se deficient rations. The mean plasma Se concentrations in the positive nonpregnant and pregnant ewes were 142 187 ng/ml and were significantly higher than Se and the corresponding values (82 and 69 ng/ml) in the Se deficient ones respectively. The plasma Se levels in the Se positive fetuses (46 ng/ml) were not significantly different from the deficient ones (53 ng/ml). The irreversible disposal (ID) rates of Se were 7 ug/d/kg body weight (B.W.) in both nonpregnant and pregnant ewes, whereas, these values declined to 2 ug/d/kg B.W. under deficiency conditions. The ID values in the Se positive and deficient fetuses were 20 and 11 ug/d/kg B.W. respectively. These results indicated that the plasma Se turnover was lower in Se deficient animals than in the positive ones and that the fetuses had a higher turnover than adult ewes irrespective of the maternal Se status. Values for net Se absorption (% Se intake) and fecal Se losses (ug/d) in the Se positive nonpregnant ewes were 51% and 272 ug/d versus 97% and 25 ug/d in the Se deficient ones. The corresponding values for the Se positive pregnant ewes were 56% and 241 ug/d as against 84% and 27 ug/d in the deficient ones. These results suggested that the efficiency of net Se absorption expressed as the percent of Se intake decreased with increasing Se intakes and that the fecal route exerted a homeostatic control on Se metabolism in ewes. The tissue Se concentrations were significantly higher in the Se positive animals than in the deficient ones, whereas, the tissue fractional rate constant values were higher in the Se deficient animals than in the positive ones. These results implied that the tissue Se concentrations were significantly decreased under Se deficiency conditions and that the Se turnover was higher in tissues when the dietary Se intake was minimal. The placental transfer studies showed that there was a bidirectional exchange of Se across the placenta. The placental Se transfer rates from ewe to fetus declined from 53 ug/d in the positive ewes to 29 ug/d in the deficient ones. The rate of Se transfer from fetus to ewe also decreased from 24 ug/d in the positive ewes to 12 ug/d in the deficient ones. The net placental Se transfer was found to be reduced under conditions of decreased maternal dietary supply. The nutritional implications of Se status of the pregnant ewes on the availability of the trace mineral to the fetus have been discussed.
Land and Food Systems, Faculty of
Graduate
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Van, der Weyde Marlene P. "The effects of the beta-adrenergic agonist, ritodrine, in the fetal lamb." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30417.

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Ritodrine is a beta-adrenergic agonist commonly used to inhibit premature labor contractions in women. The primary goal of ritodrine tocolysis is to prolong gestation, however, other indications may include fetal distress. The purpose of the current study was to examine the metabolic and behavioral effects of ritodrine in the fetus, using the chronically instrumented pregnant sheep as an experimental model. Ritodrine was infused continuously into 11 fetal lambs at a rate of 2.6 ug/minute for a period of 8, 12 or 24 hours. Samples were taken simultaneously at predetermined time periods from a fetal femoral artery, umbilical vein, maternal femoral artery and uterine vein for the analysis of fetal and maternal arterial and umbilical and uterine venous blood gases, acid-base status, hematocrit, ritodrine concentration, uterine and umbilical blood flow, and glucose, lactate and oxygen concentrations and fluxes. Cardiovascular and behavioral variables were monitored continuously. The average concentration of ritodrine in fetal arterial plasma was 20.0 ± 2.7 ng/ml (range 9.5 to 3 4.7 ng/ml) at the end of the infusion. This concentration is within the range of cord levels obtained in ritodrine exposed human fetuses at birth (7 to 79 ng/mL) . Fetal arterial plasma ritodrine levels at 8 hours post-infusion were still sufficiently elevated to exert considerable fetal effects. The apparent tolerance of the fetus to given plasma levels of drug varied considerably among animals. The infusion of ritodrine resulted in many typical beta-adrenergic receptor mediated responses in the fetus. Fetal arterial glucose levels rose to 79% above the control by the end of the infusion. This was associated with an increase in fetal glucose delivery (70% above the control), a decrease in the umbilical veno-arterial glucose concentration difference and a tendency for fetal glucose uptake to decline. Fetal arterial plasma lactate concentrations rose more than fivefold during the infusion of ritodrine. This was associated with a rise in fetal lactate delivery (540% above the control), a slight increase in the umbilical veno-arterial plasma lactate concentration difference and a tendency for fetal lactate uptake to rise. Fetal oxygen consumption rose progressively and significantly throughout the infusion of ritodrine and during the first 8 hours of post-infusion, reaching a maximum of 22% above the control by 8 hours post-infusion. Umbilical blood flow remained unchanged, therefore umbilical oxygen delivery was not increased to meet the additional oxygen demands of the fetus. The rise in fetal oxygen consumption was hence accomplished through an increase in fetal fractional oxygen extraction (from a control value of 32.0±1.1% to a maximum of 51.6±1.8% by 1.5 hours of infusion). The rise in fetal oxygen extraction resulted in concurrent declines in fetal arterial Po₂ (78% of the control) and O₂ content (55% of the control) and a widening of the veno-arterial oxygen content difference. By the end of the infusion, umbilical venous Po₂ and O₂ content values had also fallen significantly to 78% and 75% of the control respectively. These latter changes resulted in a concurrent 25% decline in fetal oxygen delivery which in turn contributed to the rise in fetal oxygen extraction. Fetal arterial and umbilical venous pH declined rapidly and significantly from control values of 7.370±0.004 and 7.401±0.005 to 7.274±0.025 and 7.306±0.023 respectively by the end of the infusion. The acidemia was reflected by significant declines in base excess values and appeared to be entirely metabolic in nature, resulting from elevated blood lactate levels. The acidemia likely contributed to the progressive fall in fetal blood O₂ content through a rightward shift of the oxyhemoglobin dissociation curve (Bohr effect). The rise in fetal oxygen consumption was reflected by a similar (although nonsignificant) increase in uterine oxygen consumption. Uteroplacental oxygen consumption appeared to remain unaltered. The rise in uterine oxygen consumption was not accompanied by a corresponding increase in uterine oxygen delivery, hence uterine oxygen extraction rose to 23.8±1.9% (from a control value of 19.5±1.6%) by 1.5 hours post-infusion. The rise in uterine oxygen extraction resulted in significant declines in uterine venous Po₂ and CO₂ values which likely contributed to the fall in fetal oxygen delivery. Fetal heart rate increased significantly to 21% (34 beats per minute, bpm) above the control (162±7 bpm) during the first 1.5 hours of ritodrine infusion. It remained elevated by an average of 16% (26 bpm) throughout the remainder of the infusion and the first 8 hours of post-infusion, returning to the control by the end of the post-infusion period. Fetal arterial pressure remained unchanged from the control (46.2±1.5 mm Hg). The incidence of fetal breathing activity fell significantly from an overall average control value of 43.2±2.6% to an average of 28.1±6.8% during the ritodrine infusion period. In most animals, breathing was most depressed near the end of the infusion. The incidence of low voltage electrocortical (ECoG) activity also fell significantly by an average of 7.5% while that of high voltage ECoG rose by 7.3%. Alterations in intermediate voltage activity were not observed. The incidence of fetal rapid eye movement also tended to fall by an average of 8.2% during the infusion of ritodrine. These behavioral changes may have resulted from the development of fetal hypoxemia, rather than as a direct effect of ritodrine. In conclusion, these data have demonstrated that ritodrine infusion to fetal lambs results in significant physiological and behavioral changes in the fetus. These effects may put the fetus at risk, particularly in situations where fetal oxygen delivery is already reduced, as in various states of compromised pregnancy.
Medicine, Faculty of
Obstetrics and Gynaecology, Department of
Graduate
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4

Knight, Kathleen Elizabeth. "Hindlimb blood flow and oxygen consumption in the late gestation fetal lamb." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0031/NQ38915.pdf.

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Smith, Gordon C. S. "The expression of prostanoid receptor genes in uterine and fetal tissues : studies in the maternal and fetal baboon and the fetal and neonatal lamb." Thesis, University of Glasgow, 2000. http://theses.gla.ac.uk/40962/.

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1. The aim of this project was to determine whether advancing gestational age and parturition were associated with alteration in the relative level of expression of genes encoding prostanoid receptors in key uterine and fetal tissues. I also sought to determine whether advancing gestational age and parturition were associated with alteration in the expression of genes encoding lipoxygenase (LOX) enzymes in key intra-uterine tissues. 2. Caesarean hysterectomy was performed on 15 pregnant baboons in the last third of pregnancy. Samples of myometrium (from multiple uterine sites), cervix, decidua and chorion were obtained. In addition, the ductus arteriosus was obtained from nine fetal baboons, 28 fetal lambs and 4 neonatal lambs. Expression of genes was studied using Northern blot analysis and in situ hybridization. Expression of genes was quantified by Northern analysis as a ratio of the signal for the gene of interest to each of three housekeeping genes (glyceraldehyde-3-phosphate dehydrogenase [GAPDH], beta-actin and cyclophilin). Statistical comparison of the effects of gestational age and labour was performed using linear regression. Student's t-test, repeated measures analysis of variance and analysis of covariance, as appropriate. 3 Initial studies of animals not in labour using cDNA probes demonstrated transcripts of similar size to the human genes for prostanoid EP2, EP3, EP4, and FP receptor mRNA using Northern blot in myometrium. Myometrium from the lower uterine segment (LUS) had greater expression of EP2 receptor mRNA and less expression of EP3 mRNA compared with the fundus and corpus. However, similar levels of EP4 and FP receptor mRNA were observed comparing the fundus and LUS. Expression of EP2, EP3 and EP4 receptor mRNA were also detected in cervix, decidua and chorion. EP2 mRNA was most abundant in cervix, EP3 was most abimdant in myometrium and EP4 mRNA was most abundant in decidua. The variation in myometrial expression of genes encoding EP receptor sub-types paralleled the contractile responses of paired samples (reported elsewhere). 4 When expression of prostanoid receptor genes was studied in myometrium obtained from animals both in labour and not in labour and the techniques employed were optimized (principally the use of riboprobes), transcripts of similar size to the human genes were detected for prostanoid EP1, EP2, EP3, EP4, IP, FP and TP receptor mRNA using Northern blot. There were no gestational age related changes in expression of these genes. Expression of EP1, EP3 and IP receptor mRNA was significantly higher in myometrium from the fundus (compared with lower segment) whereas EP2 gene expression was significantly lower in the fundus. Labor was associated with a reduction in the regional variation of both EP2 and IP receptor gene expression, but not EP1 and EP3 expression. Labor was also associated with an overall lower level of expression of EP2 receptor mRNA. 5 When expression of prostanoid receptor genes was studied in cervix obtained from animals both in labour and not in labour, clear signals which were similar in estimated size to the human genes were detected by Northern analysis for EP1, EP2, EP3, EP4, FP, IP and TP receptors. Expression of the gene encoding the prostanoid EP? receptor increased with advancing gestational age prior to labor. Expression of the EP2, FP and TP receptor genes was much lower in animals that were delivered during spontaneous labor than in animals which were not in labor. 6 When expression of prostanoid receptor genes was studied in decidua and chorion obtained from animals both in labour and not in labour, expression of the genes encoding the EP1 and FP receptor in decidua and the EP4 receptor in chorion was lower with advancing gestational age. Expression of the EP? receptor gene was lower in labour in decidua, whereas expression of the IP receptor gene was higher in labour in both decidua (2-fold) and chorion (4-fold).
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Morrison, Janna L. "Physiologic responses of the fetal lamb to eight day fluoxetine exposure during late gestation." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ61148.pdf.

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Kleemann, D. O. "A study of factors affecting embryonic, fetal and lamb survival in high fecundity merino ewes." Title page, table of contents and abstract only, 1994. http://web4.library.adelaide.edu.au/theses/09PH/09phk638.pdf.

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Bibliography : leaves 120-133. Defines the sources of reproductive wastage in FecB FecÊ Booroola Merino x South Australian Merino ewes and examines factors associated with the survival of embryos, fetuses and lambs with the aim of improving net reproduction efficiency. Experiments were conducted to define the problem; to examine factors affecting embryonic and fetal loss; and, to investigate factors influencing wastage at lambing.
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Burry, Andrea F. "The inter-relation of TGF-Beta, LC3 and apolipoprotein D in the fetal lamb ductus arteriosus." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0011/MQ40768.pdf.

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Bratu, Ioana. "Long growth, structural remodeling, surfactant levels, and lung function after reversible fetal lamb tracheal occlusion in congenital diaphragmatic hernia." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33383.

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The effects of reversible fetal tracheal occlusion (TO), and antenatal glucocorticoids on lung growth, structure, surfactant levels, and function were assessed in a lamb hypoplastic lung model of congenital diaphragmatic hernia (CDH). CDH, CDH+TO, CDH+TO+release of the tracheal occlusion one week before delivery (TR), and unoperated twin controls were compared. TO+/-TR partially normalized the hypoplastic lungs of CDH: they accelerated growth of both lungs and led to structural maturity. Only TO thinned the medial area of small pulmonary arteries closer to control values. Despite TO, TR, and glucocorticoids, lungs from lambs with CDH have dysfunctional type II cells with decreased surfactant levels. Nonetheless, CDH+TO lambs showed normal oxygenation, ventilation, and compliance over untreated CDH, with a clear survival advantage over an eight hour resuscitation. TR one week before delivery had no added benefit in terms of lung function. It appears that surfactant independent mechanisms such as pulmonary growth and structural changes are of foremost importance in relating to improved compliance, oxygenation, and ventilation of CDH+TO animals.
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Butter, Andreana. "Lung growth and lung function after a) fetal lamb tracheal occlusion and exogenous surfactant at birth in congenital diaphragmatic hernia and b) selective perfluorocarbon distention in healthy newborn piglets." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33073.

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This study sought to maximize prenatal and postnatal interventions in order to accelerate lung growth and improve lung function in two animal models. Prenatal interventions consisted of fetal tracheal occlusion (TO), antenatal glucocorticoids and exogenous surfactant at birth (SURF) in an ovine model of congenital diaphragmatic hernia (CDH). CDH, CDH+TO, CDH+SURF, CDH+TO+SURF and unoperated twin control lambs were compared. Prenatal growth of both lungs was accelerated after fetal TO. Prophylactic surfactant did not improve gas exchange or ventilation but did increase lung compliance over 8 hours. The incidence of tension pneumothoraces was slightly decreased after exogenous surfactant. Fetal TO yields the best results in terms of overall postnatal lung function, likely acting via surfactant independent mechanisms.
Postnatal intervention involved perfluorocarbon (PFC) liquid distention of the right upper lobe in healthy newborn piglets. Postnatal lung growth, as measured indirectly by rates of DNA synthesis, was not accelerated after PFC distention.
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Books on the topic "Fetal lamb"

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Burry, Andrea F. The inter-relation of TGF-Beta, LC3 and apolipoprotein D in the fetal lamb ductus arteriosus. Ottawa: National Library of Canada, 1998.

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Mike, Couffer, ed. The cats of Lamu. New York: Lyons Press, 1998.

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Dornan, James Kenneth. Responses of the fetal lamb to induced hypo- and hyperglycaemia. 1985.

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Losty, Paul Damien. Towards reducing the mortality of congenital diaphragmatic hernia: Experimental studies inthe rat and fetal lamb CDH models. 1996.

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Walker. Lab Outline Fetal Pig. Freeman & Company, W. H., 1997.

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Namm and Cocanour. Lab Manual with Fetal Pig Dissection. McGraw Hill Higher Education, 1992.

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Marieb, Elaine Nicpon. Human Anatomy & Physiology Lab Manual (fetal Pig Version): FETAL PIG VERSION. 5th ed. ADDISON-WESLEY/CUMMINGS, 1996.

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undifferentiated, Fox. Lab Gd Human A&p-fetal Pig. BROWN, W.C., COMPANY, 1986.

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Allen, C. Fetal Pig Dissection Manual & Human Anatomy Lab Guide Set. John Wiley & Sons Inc, 2003.

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Benson. A & P Lab Txtk 2e Inter(Fetal PG)I. McGraw-Hill Education, 1993.

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Book chapters on the topic "Fetal lamb"

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Acker, H., B. Bölling, F. Degner, and J. Hilsmann. "Oxygen Supply in the Fetal and Newborn Lamb Carotid Body." In Chemoreceptors and Chemoreceptor Reflexes, 141–46. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4684-8938-5_21.

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Towell, Molly E. "THE RELATIONSHIP BETWEEN ARTERIAL AND TISSUE PO2 IN THE FETAL LAMB." In Intrapartum biochemical monitoring of the fetus, edited by Molly S. Chatterjee, 139–50. Berlin, Boston: De Gruyter, 1989. http://dx.doi.org/10.1515/9783110889734-013.

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Dawes, G. S. "The Control of Fetal Heart Rate and Its Variability in Lambs." In Fetal Heart Rate Monitoring, 187–90. Berlin, Heidelberg: Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-642-70358-4_19.

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Metsälä, T., J. Grönlund, A. Siimes, and I. Välimäki. "Respiratory Heart Rate Variability in Fetal and Neonatal Lambs." In Cardiorespiratory and Motor Coordination, 259–64. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-75507-1_28.

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Egan, E. A., M. S. Kwong, and R. H. Notter. "Absorption of Fetal Lung Liquid and Exogenous Surfactant in Premature Lambs." In Physiology of the Fetal and Neonatal Lung, 209–23. Dordrecht: Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-4155-7_15.

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Walker, D. W. "Comparison of the Effects of Anti-NGF and Thyroidectomy on Sympatho-Adrenal Function in Fetal Lambs." In The Endocrine Control of the Fetus, 121–25. Berlin, Heidelberg: Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/978-3-642-72975-1_10.

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Verhoeff, A., T. C. Jansen, A. R. van der Wiel, and H. C. S. Wallenburg. "Experimental head compression and transcutaneous oxygen tension in the fetal lamb." In Fetal Physiological Measurements, 177–84. Elsevier, 1986. http://dx.doi.org/10.1016/b978-0-407-00450-4.50028-9.

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J. McCullagh, Peter, and Wayne R. Hein. "Techniques for the study of developmental immunology in the fetal lamb." In Immunology Methods Manual, 2023–35. Elsevier, 1996. http://dx.doi.org/10.1016/b978-012442710-5.50228-8.

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JMCCULLAGH, P., and W. RHEIN. "Techniques for the study of developmental immunology in the fetal lamb." In Immunology Methods Manual, 2023–35. Elsevier, 1996. http://dx.doi.org/10.1016/b978-012442710-5/50228-8.

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Morgenstern, J., T. Abels, R. Leblanc, and T. Somville. "Computation and evaluation of heart-rate and stroke volume oscillations in fetal lambs." In Fetal Physiological Measurements, 267–73. Elsevier, 1986. http://dx.doi.org/10.1016/b978-0-407-00450-4.50039-3.

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Conference papers on the topic "Fetal lamb"

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Lo Presti, Giuseppe, Lorenzo Cortese, Sergio Berdún, Elisenda Eixarch, Eduard Gratacós, and Turgut Durduran. "Measurement of fetal cerebral blood flow of the lamb fetus in utero." In Diffuse Optical Spectroscopy and Imaging, edited by Hamid Dehghani and Heidrun Wabnitz. SPIE, 2019. http://dx.doi.org/10.1117/12.2526732.

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Larson, Abby C., Ryne A. Didier, Jonathan Chang, Samantha A. Tilden, Travis M. Kotzur, Anush Sridharan, Holly L. Hedrick, and Emily A. Partridge. "The Fetal Lamb Model of Congenital Diaphragmatic Hernia Shows Increased Lung Stiffness Using Shear Wave Elastography." In AAP National Conference & Exhibition Meeting Abstracts. American Academy of Pediatrics, 2021. http://dx.doi.org/10.1542/peds.147.3_meetingabstract.953.

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Schecter, Samuel C., Mozziyar Etemadi, James A. Heller, Eveline Shue, William T. Ferrier, Shuvo Roy, and Doug Miniati. "Characterization Of In Vivo Fetal Intra-Airway Pressures In The Lamb Model Of Congenital Diaphragmatic Hernia." In American Thoracic Society 2012 International Conference, May 18-23, 2012 • San Francisco, California. American Thoracic Society, 2012. http://dx.doi.org/10.1164/ajrccm-conference.2012.185.1_meetingabstracts.a6877.

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Mynard, Jonathan P., Malcolm R. Davidson, Daniel J. Penny, and Joseph J. Smolich. "Modelling Pressure Losses at Arterial Junctions With Application to Junctions of the Fetal Ductus Arteriosus." In ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80180.

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In one-dimensional (1D) models of arterial networks, branch junctions are represented by flow and mechanical energy (or total pressure, i.e. p + 1/2ρu2) coupling conditions. The flow condition simply ensures conservation of mass, but the pressure condition is less trivial because pressure losses are known to occur in the vicinity of junctions, caused by regions of complex flow that depend on the vascular geometry and prevailing flow patterns. These losses are commonly ignored in 1D models under the assumption that area ratios and branching angles of arterial junctions are optimally designed. However, one setting where pressure losses are likely to be important is the junction of the ductus arteriosus (DA) with the aorta in the fetus, considering the high kinetic energy of blood in the DA [1], the acute angle between the aortic isthmus (Aols) and DA, and the redirection of DA blood flow towards the descending aorta (DAo, Figure 1). Previously, pressure losses have been approximated in 1D models by enforcing continuity of static (rather than total) pressure [2] or by using empirical loss coefficients obtained from experiments in 90 degree T-tubes [3]. In the current study, we implemented a loss formulation described by Bassett et al [4] for 1D gas dynamics simulations, which unlike previous methods, can be used to model junctions with any number of branches and any orientation of branch angles, and explicitly accounts for the influence of area and flow ratios on pressure losses. Results of the model are validated against high fidelity measurements in fetal lambs.
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Sharma, Megha, Adeleye J. Afolayan, Ru-Jeng Teng, and Girija G. Konduri. "Downregulation of Cgmp Mediated Mitochondrial Biogenesis Contributes to Impaired Angiogenesis in Fetal Lambs with Persistent Pulmonary Hypertension of the Newborn (pphn)." In Selection of Abstracts From NCE 2016. American Academy of Pediatrics, 2018. http://dx.doi.org/10.1542/peds.141.1_meetingabstract.513.

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Reports on the topic "Fetal lamb"

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Spencer, Thomas E., Elisha Gootwine, Arieh Gertler, and Fuller W. Bazer. Placental lactogen enhances production efficiency in sheep. United States Department of Agriculture, December 2005. http://dx.doi.org/10.32747/2005.7586543.bard.

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The key objectives of this BARD project were to: (1) study long-term effects of immunization of prepubertal ewes against recombinant ovine placental lactogen (roPL) on subsequent birth weights of their lambs and their milk production; (2) optimize the anti-roPL immunization protocol using adjuvant preparations acceptable to producers and regulatory agencies; and (3) determine the physiological mechanism(s) whereby immunization against oPL increases fetal growth and development and mammogenesis. These objectives were based on key findings from a previous BARD project that: (a) immunization of ewes against roPL increased lamb birth weight and ewe milk production during lactation; (b) roPL and recombinant ovine growth hormone (roGH) increased the proliferation and differentiated function of endometrial glands that, in turn, would enhance uterine secretions necessary for fetal and placental growth; and (c) exogenous roPL and roGH stimulated mammogenesis and milk production during lactation. The BARD projects address central problems in sheep production, including reproductive failure due to embryonic/fetal mortality, low birth weight of lambs especially in prolific breeds, and reduced milk yields which affect neonatal survival. The sheep placenta secretes both lactogenic (oPL) and somatogenic (oGH) hormones. The receptors for those hormones are present in the fetus and placenta as well as maternal uterus, and mammary gland. Our research has focused on determining the biological role of these placental hormones in development and differentiation of the uterus during gestation and the mammary gland during pregnancy and lactation. Studies conducted in the current BARD project indicated that the effects of anti-roPL immunization were variable in ewes and that commercially available and widely acceptable adjuvant preparations were not effective to produce high anti-roPL titers in pre-pubertal ewes. In the non-prolific Rambouillet ewe in Texas and in the Awassi and the Assaf in Israel, anti-roPL immunization increased lamb birth weight; however, the magnitude of this effect and the inherent variability precluded our ability to determine the physiological mechanism of how the immunization increases fetal growth. Collectively, our findings suggest that anti-roPL immunization is not currently feasible as an easy and efficacious tool for the producer to increase flock reproductive and production efficiency. The variability in response of individual ewes to anti-roPL immunization likely includes modifying the recombinant hormone and the type of adjuvant used for the immunization. In particular, the oPL may need to be modified to ensure maximum antigenicity in a broad range of breed types. Nonetheless, the investigators continue to collaborate on identifying fundamental mechanisms that can be improved by genetics or management to enhance the efficiency of uteroplacental function and, in turn, fetal growth and development. High prolificacy is a desirable trait in intensive sheep production systems. One of the main limitations of using prolific breeds of sheep is that increased litter size is associated with low birth weights and increased mortality of lambs. Further, low birth weight is associated with an increased propensity for adult diseases and decreased production efficiency. Indeed, our recent studies find that the birth weights of lambs born in large litters can be improved by both genetics and management. Future cooperative research will continue to focus on reproductive efficiency of sheep that have broader implications for improving production efficiency in all types of ruminant livestock.
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Bazer, Fuller W., Arieh Gertler, and Elisha Gootwine. Role of Placental Lactogen in Sheep. United States Department of Agriculture, January 2001. http://dx.doi.org/10.32747/2001.7574339.bard.

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Central problems in sheep and dairy cattle production are reproductive failure due to embryonic/fetal mortality and low birth weights, especially in prolific breeds, and reduced milk yields which adversely affect neonatal survival and economy of production. The sheep placenta expresses lactogenic (ovine placental lactogen, oPL) and somatogenic (ovine placental growth hormone, oGH) hormones. Our research has focused on the biological roles of oPL and oGH in function of the uterine endometrium during gestation and the mammary gland during pregnancy and lactation. Major conclusions were that: ( 1 ) immunization of prepubertal ewes against oPL resulted in increased birth weights of their lambs and their milk production during lactation; (2) neither oPL nor oGH had an antiluteolytic effect on uterine endometrium to affect lifespan of the corpus luteum; (3) only sequential exposure of the progesterone stimulated uterus to oIFNt and oPL or oGH increased endometrial gland proliferation and secretory protein gene expression; (4) oPL signals through a homodimer of ovine prolactin receptor (PRL-R) and heterodimer of oPRL-R and growth hormone receptor (GH-R); (5) exogenous recombinant oPL and oGH stimulated mammogenesis and milk yield during lactation; and (6) mutation of oPL and oGH was used to define specific biological effects and a rational basis for design of a specific receptor agonists or antagonists. This project was very productive in elucidating basic biological effects of oPL and oGH on intracellular signal transduction pathways, uterine development and secretory function, as well as mammogenesis and lactogenesis. We determined that immunization of prepubertal ewes against roPL increased birth weights of their lambs, especially those born as twins and triplets, as well as enhanced lactational performance. These studies significantly extended our knowledge of uterine and fetal-placental physiology and provided a foundation for new strategies to enhance reproductive and lactation efficiency. Based on these results, the major achievements were: 1) creation of a practical and cost effective management tool for producers to increase reproductive performance, neonatal survival, and milk yield of ewes in commercial flocks; and 2) define, for the first time, biological effects of oPL on endometrial functions and gene expression by uterine gland epithelium.
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Needham, Glenn R., Uri Gerson, Gloria DeGrandi-Hoffman, D. Samatero, J. Yoder, and William Bruce. Integrated Management of Tracheal Mite, Acarapis woodi, and of Varroa Mite, Varroa jacobsoni, Major Pests of Honey Bees. United States Department of Agriculture, March 2000. http://dx.doi.org/10.32747/2000.7573068.bard.

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Objectives: The Israeli work plan regarding HBTM included: (a) producing a better diagnostic method; (b) following infestations during the season and evaluating damage to resistant bees and, (c) controlling HBTM by conventional means under local conditions. For varroa our plans to try novel control (e.g. oil novel control (e.g. oil patties & essential oils) were initially delayed by very low pest populations, then disrupted by the emergence of fluvalinate resistance. We monitored the spread of resistance to understand it better, and analyzed an underlying biochemical resistance mechanism in varroa. The US work plan focused on novel management methods for both mites with an emphasis on reducing use of traditional insecticides due to resistance and contamination issues. Objectives were: (a) evaluating plant essential oils for varroa control; (b) exploring the vulnerability of varroa to desiccation for their management; and (c) looking for biological variation in HBTM that could explain virulence variability between colonies. Although the initial PI at the USDA Beltsville Bee Lab, W.A. Bruce, retired during the project we made significant strides especially on varroa water balance. Subcontracts were performed by Yoder (Illinois College) on varroa water balance and DeGrandi-Hoffman (USDA) who evaluated plant essential oils for their potential to control varroa. We devised an IPM strategy for mite control i the U.S. Background: Mites that parasitize honey bees are a global problem. They are threatening the survival of managed and feral bees, the well-being of commercial/hobby beekeeping, and due to pollination, the future of some agricultural commodities is threatened. Specific economic consequences of these mites are that: (a) apiculture/breeder business are failing; (b) fewer colonies exist; (c) demand and cost for hive leasing are growing; (d) incidences of bee pathogens are increasing; and, (e) there are ore problems with commercial-reared bees. As a reflection of the continued significance f bee mites, a mite book is now in press (Webster & delaplane, 2000); and the 2nd International Conference on Africanized Honey Bees and Bee Mites is scheduled (April, 2000, Arizona). The first such conference was at OSU (1987, GRN was co-organizer). The major challenge is controlling two very different mites within a colony while not adversely impacting the hive. Colony management practices vary, as do the laws dictating acaricide use. Our basic postulates were that: (a) both mites are of economic importance with moderate to high infestations but not at low rates and, (b) once established they will not be eradicated. A novel strategy was devised that deals with the pests concomitantly by maintaining populations at low levels, without unnecessary recourse to synthetic acaricides. Major Conclusions, Solutions, Achievements: A major recent revelation is that there are several species of "Varroa jacobsoni" (Anderson & Trueman 1999). Work on control, resistance, population dynamics, and virulence awaits knowing whether this is a problem. In the U.S. there was no difference between varroa from three locales in terms of water balance parameters (AZ, MN & PA), which bodes well for our work to date. Winter varroa (U.S.) were more prone to desiccation than during other seasons. Varroa sensitivity to desiccation has important implications for improving IPM. Several botanicals showed some promise for varroa control (thymol & origanum). Unfortunately there is varroa resistance to Apistan in Israel but a resistance mechanism was detected for the first time. The Israel team also has a new method for HBTM diagnosis. Annual tracheal mite population trends in Israel were characterized, which will help in targeting treatment. Effects of HBTM on honey yields were shown. HBTM control by Amitraz was demonstrated for at least 6 months. Showing partial resistance by Buckfast bees to HBTM will be an important IPM tactic in Israel and U.S.
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