On the origin of dehydroepiandrosterone sulphate in the blood of fetal sheep

1985 ◽  
Vol 104 (2) ◽  
pp. 279-283 ◽  
Author(s):  
G. C. Liggins ◽  
J.-C. Schellenberg ◽  
F. Amato ◽  
B. Godfrey ◽  
R. F. Seamark
Keyword(s):  
Significant Contribution ◽  
Late Pregnancy ◽  
Dehydroepiandrosterone Sulphate ◽  
Fetal Sheep ◽  
Intact Group ◽  
The Mean ◽  
Ovine Fetal

ABSTRACT Total sulphoconjugated and unconjugated dehydroepiandrosterone (DHA) and total oestrone were measured in plasma of intact sheep fetuses, fetuses hypophysectomized at 104–112 days and fetuses bilaterally adrenalectomized at 98–101 days. At 120–127 days, the mean concentrations of total DHA and oestrone in intact fetuses (n = 13) were 29·7 ± 4·2 (s.e.m.) nmol/l and 14·3 ± 2·8 nmol/l respectively. At term, the values for total DHA and oestrone in hypophysectomized fetuses (n = 13) of 18·0 ± 1·9 nmol/l and 9·1 ±2·0 nmol/l were significantly (P <0·05) lower than the intact group whereas in the adrenalectomized fetuses (n = 8) total DHA (80·8±13·0 nmol/l) was higher (P < 0·05) and total oestrone values were similar to the intact animals. Intrafetal infusion of cortisol at term (1 mg/h for 84 h) raised levels of total oestrone in intact (n = 6; 12·3 ± 2·9 vs 31·6± 8·5 nmol/l) and adrenalectomized (n = 4; 14·2 ± 2·6 vs 190·6 ± 53·0 nmol/l) fetuses and of total DHA in hypophysectomized fetuses (n = 7; 16·0±1·9 vs 31·6 ± 8·5 nmol/l) while infusion of ACTH(1–24) (5 μg/h) was without significant effect in any group. It is concluded that the ovine fetal adrenal in late pregnancy makes no significant contribution either to the high circulating concentrations of DHA sulphate or to the substrates for placental oestrogen synthesis. J. Endocr. (1985) 104, 279–283

Regulation of ovine fetal pituitary function by corticotrophin-releasing hormone, arginine vasopressin and cortisol in vitro

1994 ◽  
Vol 143 (1) ◽  
pp. 199-208 ◽  
Author(s):  
F Lü ◽  
K Yang ◽  
J R G Challis
Keyword(s):  
Arginine Vasopressin ◽  
Binding Sites ◽  
Late Pregnancy ◽  
Fetal Sheep ◽  
Releasing Hormone ◽  
Fetal Organ ◽  
Pomc Mrna ◽  
Dose Dependent Fashion ◽  
Ovine Fetal

Abstract Parturition and fetal organ maturation in sheep are associated with increased activity of the fetal hypothalamic-pituitary-adrenal (HPA) axis during late pregnancy. However, the factors responsible for HPA activation remain unclear. In the fetal pituitary, levels of pro-opiomelanocortin (POMC) mRNA increase, but the numbers of binding sites for corticotrophin-releasing hormone (CRH), and ACTH responsiveness to exogenous CRH decline during the last 20 days of pregnancy. We have examined regulation of CRH binding, pituitary ACTH responsiveness, and levels of POMC mRNA in cultures of adenohypophysial cells from term fetal sheep. After a 4-day stabilization period, output of immunoreactive (ir) ACTH was increased over 48 h in a dose-dependent fashion by both CRH and arginine vasopressin (AVP) but decreased by cortisol. Subsequent output of ir-ACTH to a 3-h challenge with 100 nm CRH was attenuated after pretreatments with CRH, AVP or cortisol; the effect of CRH being greater than that of cortisol or AVP. At the end of 48 h of treatment with CRH, AVP or cortisol, there was a 40–50% reduction in the number of CRH-binding sites, but the levels of POMC mRNA decreased significantly only after cortisol treatment and were not altered significantly by CRH or AVP. We conclude that under the conditions of these experiments, CRH and AVP increase ir-ACTH output without increasing the level of steady-state POMC mRNA, but may contribute to loss of pituitary responsiveness to CRH by down-regulation of CRH receptor number. Cortisol exerts negative feedback on POMC mRNA and decreases the number of CRH receptors. Thus, any one or all of CRH, AVP and cortisol could be responsible for the decline in CRH binding in the fetal sheep pituitary during late pregnancy. Although CRH and AVP may affect secretion of ir-ACTH, the present results do not support a role for these neuropeptides in affecting the level of POMC mRNA in the fetal sheep pituitary. Journal of Endocrinology (1994) 143, 199–208

Decreases in ovine fetal cartilage sulfate uptake and serum sulfate during gestation

1985 ◽  
Vol 249 (1) ◽  
pp. E115-E120
Author(s):  
F. H. Morriss ◽  
R. N. Marshall ◽  
S. S. Crandell ◽  
B. J. Fitzgerald ◽  
L. Riddle
Keyword(s):  
Human Serum ◽  
Costal Cartilage ◽  
Full Term ◽  
Late Gestation ◽  
In Vitro Assays ◽  
Sulfate Uptake ◽  
Fetal Sheep ◽  
Ovine Fetal ◽  
Serum Sulfate

In vitro assays for [35S]sulfate uptake by ovine fetal costal cartilage were used to assess gestational changes in cartilage metabolism. Addition of 20% normal human serum to the incubation medium increased fetal cartilage [35S]sulfate incorporation into glycosaminoglycans. Both basal and human serum-stimulated uptakes of [35S]sulfate by fetal sheep cartilage decreased from midgestation to full term. The incremental response in [35S]sulfate uptake that was stimulated by human serum decreased as gestation proceeded to full-term. Fetal serum sulfate concentration decreased logarithmically during gestation, raising the possibility that cartilage sulfate uptake might become substrate limited as full term is approached. Perfusion of seven late gestation sheep fetuses for 7 days with Na2SO4 to achieve serum sulfate concentrations similar to those observed earlier in gestation resulted in a 33% increase in mean cartilage [35S]sulfate uptake compared with that of control twin fetuses, but uptake was not increased to values that occurred spontaneously earlier in gestation. These results suggest that the decreasing rate of [35S]sulfate uptake by fetal cartilage during the last half of gestation is associated only minimally with decreasing serum sulfate levels and is most consistent with intrinsic change in resting chondrocyte metabolism during gestation.

DIE AUSSCHEIDUNG VON TESTOSTERON UND EPITESTOSTERON BEI FRAUEN AM ENDE DER SCHWANGERSCHAFT

1969 ◽  
Vol 60 (4) ◽  
pp. 579-585
Author(s):  
K. Schollberg ◽  
E. Seiler ◽  
J. Holtorff
Keyword(s):  
Urinary Excretion ◽  
Late Pregnancy ◽  
Mean Values ◽  
Pregnant Females ◽  
Female Foetus ◽  
The Mean ◽  
The Difference ◽  
Normal Women ◽  
In Pregnancy

ABSTRACT The urinary excretion of testosterone and epitestosterone by women in late pregnancy has been studied. The mean values of 22 normal women in pregnancy mens X are 12.9 ± 9.2 μg/24 h in the case of testosterone and 16.1 ± 16.2 μg/24 h in the case of epitestosterone. Both values do not differ significantly from those of non-pregnant females. The excretion values of mothers bearing a male foetus (17.3 ± 8.9 μg/24 h) are higher than those of mothers with a female foetus (6.4 ± 4.8 μg/24 h). The difference is statistically significant with P = 0.01.

Regulation of lactic acid production during exercise

1988 ◽  
Vol 65 (2) ◽  
pp. 509-518 ◽  
Author(s):  
A. Katz ◽  
K. Sahlin
Keyword(s):  
Lactic Acid ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Synergistic Effect ◽  
Lactic Acid Production ◽  
Fetal Lung ◽  
Lung Maturation ◽  
Fetal Sheep ◽  
Epidermal Growth ◽  
Ovine Fetal

Cortisol has minimal effects on lung maturation in fetal sheep before 130 days gestation. To test whether there is enhancement of cortisol action by other hormones, cortisol (F), triiodothyronine (T3), epinephrine (E), prolactin (PRL), and epidermal growth factor (EGF), alone or in combination, were infused into fetal sheep for 84 h between 124 and 128 days gestation. A mixture of F + T3 + PRL, but not any combination of two hormones, increased both distensibility [1.71 +/- 0.12 (SE) ml of air/g wet wt at 40 cmH2O, V40] and stability (1.16 +/- 0.09 ml of air per g wet wt at 5 cmH2O, V5) to near full-term values, above values resulting from treatment with F alone (0.91 +/- 0.12 and 0.43 +/- 0.09 ml/g, P less than 0.01). Only F had an effect when given alone, V40 increasing (P less than 0.05). Treatment with F + T3 (0.81 +/- 0.18 ml/g) and F + E (0.77 +/- 0.07 ml/g) increased V5 above values obtained with F alone (P less than 0.05). Alveolar saturated phosphatidylcholine (SPC) was higher after treatment with F + T3 (161 +/- 52 micrograms/g), F + T3 + PRL (156 +/- 53 micrograms/g, P less than 0.05), and F + E (113 +/- 40 micrograms/g, P = 0.07) than after F (12 +/- 3 micrograms/g). We conclude that F, T3, and PRL have a synergistic effect on the development of distensibility and stability of the ovine fetal lung.

Tone-dependent responses to endothelin in the isolated perfused fetal sheep pulmonary circulation in situ

1991 ◽  
Vol 70 (3) ◽  
pp. 1228-1234 ◽  
Author(s):  
S. Cassin ◽  
V. Kristova ◽  
T. Davis ◽  
P. Kadowitz ◽  
G. Gause
Keyword(s):  
Pulmonary Circulation ◽  
Vena Cava ◽  
Fetal Lung ◽  
Left Pulmonary Artery ◽  
Pulmonary Vasculature ◽  
Fetal Sheep ◽  
Vascular Responses ◽  
Arterial Perfusion ◽  
Ovine Fetal

Pulmonary vascular responses to endothelin (ET-1), a peptide derived from endothelial cells in culture, were investigated in the ovine fetus delivered by cesarean section from chloralose-anesthetized ewes with intact umbilical circulation. Circulation to the lower left lobe of the fetal lung was isolated in situ and perfused at constant flow with blood withdrawn from the inferior vena cava. Injection of graded doses of ET-1 into the left pulmonary artery decreased pulmonary arterial perfusion pressure in a dose-related manner. At doses of 100, 300, and 1,000 ng, pulmonary vascular resistance per kilogram body weight (PVR/kg) was decreased 30, 40, and 42%, respectively. However, when fetuses were ventilated with 100% oxygen, 100- and 300-ng doses of ET-1 decreased PVR/kg by 5 and 9%, respectively. In contrast, injection of 1,000 ng of ET-1 resulted in a reversal of the response, and PVR/kg was increased by 70%. Ventilation of the right lung alone resulted in a similar reversal of the vasodilator response to 1,000 ng of ET-1, and a 138% increase in PVR/kg was recorded. These studies demonstrate for the first time that ET-1 has vasodilator activity in the normally high-tone ovine fetal pulmonary circulation. In addition, these results show that ET-1 has vasoconstrictor activity in the newly ventilated low-tone pulmonary vasculature. The present data indicate the pulmonary vascular responses to ET-1 are tone dependent in the ovine fetal pulmonary circulation.

scholarly journals Evaluation of the relationship between spatial abilities and anatomy learning

2020 ◽  
Vol 14 (2) ◽  
pp. 139-144
Author(s):  
Mustafa Aydın ◽  
Mehmet Tuğrul Yılmaz ◽  
Muzaffer Şeker
Keyword(s):  
Mental Rotation ◽  
Spatial Ability ◽  
Significant Contribution ◽  
Spatial Abilities ◽  
School Students ◽  
Mental Rotation Test ◽  
Practical Applications ◽  
Significant Difference ◽  
The Mean ◽  
The Relationship

Objectives: The aim of this study was to examine the relationship between the spatial abilities of medical school students and their learning in anatomy. Methods: The spatial abilities of the 120 students (74 females, 46 males) were examined using Mental Rotation Test (MRT). The relationship between the mental rotation scores and the mean scores of their practical and theoretical anatomy examinations was determined in terms of gender. Results: The study revealed that mental rotation skills of female participants were lower than males; however, there was no significant difference in their exam (theoretical and practical anatomy examinations) scores in terms of gender. The spatial ability of the students had a low level significant effect on their anatomy scores, regarding practical applications. Conclusion: The results of the study revealed a significant relationship between students’ spatial ability and their success in practical anatomy examinations. This suggests that improving spatial ability skills may have a significant contribution to practical anatomy learning and may be considered as a part of anatomy education.

Altered osmotic thresholds for vasopressin secretion and thirst in human pregnancy

1984 ◽  
Vol 246 (1) ◽  
pp. F105-F109 ◽  
Author(s):  
J. M. Davison ◽  
E. A. Gilmore ◽  
J. Durr ◽  
G. L. Robertson ◽  
M. D. Lindheimer
Keyword(s):  
Plasma Osmolality ◽  
Late Pregnancy ◽  
Base Line ◽  
Urinary Volume ◽  
Human Pregnancy ◽  
Slow Infusion ◽  
Vasopressin Secretion ◽  
The Subject ◽  
The Mean ◽  
Plasma Arginine

Osmoregulation was studied in eight women during late pregnancy and again 8-10 wk postpartum. Base-line plasma osmolality (Posmol) was significantly lower during (280.9 +/- 2.1 mosmol/kg, SD) than after (289.4 +/- 2.1 mosmol/kg) pregnancy yet 24-h urinary volume and plasma arginine vasopressin (PAVP) measured in vasopressinase-inactivated blood was similar in both groups (pregnancy, 1.39 +/- 0.56 pg/ml; postpartum, 1.25 +/- 0.62 pg/ml). After 12 h of dehydration PAVP rose similarly and significantly both during (2.25 +/- 0.81 pg/ml) and after (2.89 +/- 1.19 pg/ml) gestation, and Uosmol was similar on both occasions (pregnancy, 779 +/- 121 mosmol/kg; postpartum, 784 +/- 102 mosmol/kg). When Posmol was increased by the slow infusion of 5% saline PAVP increased as soon as body tonicity did both during and after pregnancy. PAVP correlated significantly with Posmol in each subject (range of r, 0.75-0.99) and the mean regression lines [pregnancy, PAVP = 0.32 (Posmol; -279), r = 0.79; postpartum, PAVP = 0.38 (Posmol, -285), r = 0.86] demonstrated that the apparent osmotic threshold for AVP secretion was 6 mosmol/kg lower during than after gestation. Similarly the Posmol at which the subject experienced a conscious desire to drink was lower in pregnant (287 +/- 1.6 mosmol/kg) compared with postpartum subjects (298 +/- 2.0 mosmol/kg; P less than 0.001). These data demonstrate decreased osmotic thresholds for AVP release and thirst during human pregnancy and explain why gravidas can maintain their new lower Posmol within narrow limits.

scholarly journals Components of litter size in mice after 110 generations of selection

Reproduction ◽  
2004 ◽  
Vol 127 (5) ◽  
pp. 587-592 ◽  
Author(s):  
M Holt ◽  
O Vangen ◽  
W Farstad
Keyword(s):  
Litter Size ◽  
Late Pregnancy ◽  
Ovulation Rate ◽  
Control Line ◽  
Embryo Survival ◽  
High Line ◽  
Line Selection ◽  
Males And Females ◽  
The Mean ◽  
Standard Deviations

The aim of the present study was to evaluate how ovulation rate and survival rate through pregnancy had been affected by more than 110 generations of upwards selection on litter size in mice. The mean number of pups born alive was 22 in the high line (selected line) and 11 in the control line (an increase in 2.6 standard deviations). Selection on litter size increased ovulation rate by 4.6 standard deviations, and it is suggested that selection also increased embryonic mortality in late pregnancy. Embryo survival from ovulation until birth was 66% in the selected line and 69% in the control line, and the observed loss in litter size from day 16 of pregnancy until birth was possibly higher in the high line compared with the control line. Selection for higher litter size has significantly increased body weight in both males and females, as the mean weight at mating for the females was 46 g in the high line and 33 g in the control line respectively.

Urocortin: a mechanism for the sustained activation of the HPA axis in the late-gestation ovine fetus?

2002 ◽  
Vol 283 (1) ◽  
pp. E165-E171 ◽  
Author(s):  
Alison C. Holloway ◽  
David C. Howe ◽  
Gabriel Chan ◽  
Vicki L. Clifton ◽  
Roger Smith ◽  
...  
Keyword(s):  
In Situ Hybridization ◽  
Late Gestation ◽  
Pituitary Cells ◽  
Fetal Sheep ◽  
Antisense Probe ◽  
Pomc Mrna ◽  
Ovine Fetus ◽  
Ovine Fetal ◽  
Sustained Activation

We hypothesized that urocortin might be produced in the pituitary of the late-gestation ovine fetus in a manner that could contribute to the regulation of ACTH output. We used in situ hybridization and immunohistochemistry to identify urocortin mRNA and protein in late-gestation fetal pituitary tissue. Levels of urocortin mRNA rose during late gestation and were associated temporally with rising concentrations of pituitary proopiomelanocortin (POMC) mRNA. Urocortin was localized both to cells expressing ACTH and to non-ACTH cells by use of dual immunofluorescence histochemistry. Transfection of pituitary cultures with urocortin antisense probe reduced ACTH output, whereas added urocortin stimulated ACTH output from cultured pituitary cells. Cortisol infusion for 96 h in chronically catheterized late-gestation fetal sheep significantly stimulated levels of pituitary urocortin mRNA. We conclude that urocortin is expressed in the ovine fetal pituitary and localizes with, and can stimulate output of, ACTH. Regulation of urocortin by cortisol suggests a mechanism to override negative feedback and sustain feedforward of fetal hypothalamic-pituitary-adrenal function, leading to birth.

Cardiac function in fetal sheep during two weeks of hypoxemia

1994 ◽  
Vol 266 (6) ◽  
pp. R1778-R1785 ◽  
Author(s):  
M. Kamitomo ◽  
L. D. Longo ◽  
R. D. Gilbert
Keyword(s):  
Arterial Pressure ◽  
Cardiac Function ◽  
Ventricular Function ◽  
Left Ventricular ◽  
Pressure Sensitivity ◽  
Sensitivity Curve ◽  
Fetal Sheep ◽  
Cardiac Responses ◽  
Ovine Fetal

Although several studies have examined fetal cardiac responses to acute hypoxemia, relatively little is known of the response to prolonged hypoxemia. To determine the effects of long-term hypoxemia on ovine fetal cardiac function, we measured right (QRV) and left ventricular outputs (QLV) and determined the effects of increasing preload (ventricular function curve) and afterload (arterial pressure sensitivity curve) on the left ventricle. Six days after fetal surgical instrumentation with catheters and electromagnetic flow probes (approximately 123 days gestation), we administered N2 into the maternal trachea for 14 days to reduce maternal PO2 to approximately 55 Torr (hypoxemic group, Hyp, n = 6). Normoxic animals were used as controls (Cont, n = 6). With the onset of hypoxemia, fetal arterial PO2 was reduced from approximately 27 to approximately 18 Torr. Fetal heart rate in Hyp fetuses decreased approximately 22% on day 14 compared with Cont (P < 0.05). Mean arterial pressure in the Hyp group was higher than that of Cont but not significantly so. Right and left atrial pressures were not affected by hypoxemia. QRV in Hyp fetuses was maintained on day 1 but decreased significantly by day 3 (approximately 19%) and further decreased on days 7 (approximately 28%) and 14 (approximately 34%). QLV was not depressed until day 7 (approximately 20%), with a further decrease on day 14 (approximately 38%). In association with the decreased QLV the plateau of the ventricular function curve in Hyp fetuses was depressed significantly on days 7 and 14. In contrast, the slope of the arterial pressure sensitivity curve in the Hyp group did not differ from Cont.(ABSTRACT TRUNCATED AT 250 WORDS)

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