Placental glucose transport in heat-induced fetal growth retardation

In six ewes heat stressed from 39 to 125 days gestation and studied in a normothermic environment at 135 days, fetal and placental masses were less than in control sheep (1,645 vs. 3,112 and 149 vs. 356 g, respectively, P less than 0.01). Umbilical glucose uptakes (Rf,UP) were measured keeping maternal arterial plasma glucose at 70 mg/dl at spontaneously occurring fetal plasma glucose values (state A) and at two additional fetal glucose levels, to determine the transplacental glucose difference (delta) vs. Rf,UP relation. At normal delta of 49.2 mg/dl, Rf,UP was less in the experimental group (3.2 vs. 5.6 mg.min-1.kg fetus-1, P less than 0.05). Differences in placental perfusion and glucose consumption could not account for this result, thus indicating a reduced placental glucose transport capacity. In state A, fetal hypoglycemia enlarged significantly (P less than 0.01) the delta to 56.7 mg/dl and increased Rf,UP approximately 50% over the Rf,UP at a normal delta. In heat-induced fetal growth retardation, fetal hypoglycemia increases the flux of maternal glucose across a placenta with reduced glucose transport capacity.

Venous drainage of the human uterus: respiratory gas studies in normal and fetal growth-retarded pregnancies

OBJECTIVE

To determine respiratory gas relationships between the uterine veins and umbilical vein in normal and pregnancies complicated by intrauterine growth retardation.

STUDY DESIGN

Respiratory gases were measured in both uterine veins and the umbilical vein in eight normal and 13 pregnancies with intrauterine growth retardation.

RESULTS

No significant differences were found in the placental versus nonplacental uterine veins. There was a significant correlation for umbilical and uterine venous values of PO2 (p less than 0.002) and PCO2 (p less than 0.004) in appropriate-for-gestational-age pregnancies, umbilical venous PO2 was always less than uterine venous PO2, and PCO2 always greater than uterine. The transplacental gradient was significantly higher in intrauterine growth retarded than appropriate-for-gestational-age pregnancies for both POC2 and PCO2. There was a lower uterine oxygen extraction in intrauterine growth retarded pregnancies (p less than 0.05).

CONCLUSION

There is no consistent relationship between placental venous drainage in each uterine vein and placental location. The human placenta simulates a relatively inefficient venous equilibrator and the larger transplacental gradients in intrauterine growth retarded pregnancies may reflect differences in both perfusion pattern and placental structure.

Prenatal diagnosis and management of congenital heart disease

Thirty-two fetuses were diagnosed as having congenital heart disease (CHD). The major indications for level II echocardiography other than suspected cardiac abnormalities were fetal malformations, nonimmune hydrops and cardiac arrhythmia. Only three patients had a previous history of fetal CHD. No false-abnormal diagnosis of severe CHD was made. Aortic arch anomalies represented the major diagnostic problem among the six correct but incomplete diagnoses. Sixty-one percent of the fetuses were growth retarded, thus confirming the severity of their CHD. Chromosomal anomalies and extracardiac malformations were associated in 19% and 44% of the fetuses, respectively. Obstetric management and fetal prognosis in cases of extracardiac malformations were greatly influenced by the diagnosis of CHD. The poorest perinatal outcome was associated with heart failure. The only intrauterine deaths occurred in that group, and only one neonate survived. The outcome was more favorable in neonates without other malformations or heart failure. Four of ten (40%) of those neonates survived, while the overall perinatal survival rate was 24%.

The correlation of biochemical monitoring versus umbilical flow velocity measurements of the human fetus

The pulsatility index of the fetal umbilical arteries was evaluated in 14 high-risk pregnant patients delivered by cesarean section between 30 and 35 weeks of gestation. Transabdominal cord sampling by ultrasonic guidance was performed on 10 of these patients. Umbilical arterial and venous blood was obtained in all patients from the doubly clamped cord at the time of cesarean section. The blood samples were analyzed for respiratory gases, acid-base balance, and lactate concentrations. A significant relationship was found between the pulsatility index and pH, PCO2, and lactate concentrations measured on umbilical venous blood sampled in utero. The pulsatility index also correlated with the same variables measured on venous and arterial blood sampled at cesarean section. Umbilical venous blood obtained transabdominally had a significantly higher oxygen content than blood obtained at cesarean section. No significant correlation was found between umbilical venous oxygen content obtained at transabdominal cord sampling and the pulsatility index. At a pulsatility index greater than 1.5, lactate concentrations in umbilical venous blood increased sharply. There would appear to be a curvilinear relationship between umbilical blood flow and these indices of fetal oxygenation, such that moderate increases in pulsatility index were not associated with a significant increase in fetal lactate concentrations.

Fetal endoxins and complications of pregnancy

Maternal endoxin (digoxinlike substance) is proposed as arising in the fetal area of the fetal adrenal cortex. Its function may be to sensitize the uterus for labor, much as does cortisol in the sheep fetus. Because endoxin is a sodium-potassium-adenosine triphosphatase inhibitor, however, it may also induce maternal vasoconstriction. On our service, normal pregnant women have detectable endoxin after 35 weeks with increasing amounts at term. Specimens of cord blood often have "digoxin" in the therapeutic range. We find that about 40% of women in premature labor and 65% of pregnant women with hypertension have elevated levels of serum endoxin. Postdate gravid women sometimes have very low endoxin levels. Pregnant women with complications and elevated digoxin (endoxin) levels could have specific antidigoxin therapy if endoxin proves to be a modulator of their symptoms. Digoxinlike substances are also sometimes elevated in ill nonpregnant persons, such as those with renal, liver, or heart failure, or hypertension.

The relationship of maternal and fetal glucose concentrations in the human from midgestation until term

The relationship between maternal and fetal glucose concentrations was investigated in pregnant women at different gestational ages. Maternal and fetal blood samples were obtained during 14 fetoscopies (17 to 21 weeks), four umbilical cord samples (32 to 36 weeks), nine elective cesarean sections with appropriate for gestational age (AGA) fetuses (35 to 39 weeks) and nine elective cesarean sections with small for gestational age (SGA) fetuses (34 to 37 weeks). A significant linear relationship between maternal and fetal glucose concentrations was demonstrated at midgestation (P less than .001) and at late gestation (P less than .001). At equal maternal concentrations there were no significant differences in fetal glucose concentration between the cord samples obtained in late gestation and those obtained at cesarean section. At midgestation fetal glucose concentration is independent of and may exceed maternal concentration at maternal glucose levels less than 4.44 mmol/L. Furthermore, the relationship between maternal and fetal concentrations at maternal glucose concentrations greater than 4.44 mmol/L is significantly different at midgestation from that at late gestation (P less than .01); at equal maternal concentrations there were higher glucose concentrations in the mid trimester fetus. In late gestation as the maternal glucose concentration increases there is an increase in the maternal arterial-umbilical arterial glucose concentration difference and the umbilical glucose/oxygen quotient (P less than .003) reflecting increased glucose utilization by the fetus. There were no significant differences between AGA and SGA babies with respect to these relationships.

The yolk sac in early pregnancy failure

An attempt was made to visualize the yolk sac in 845 patients scheduled for chorionic villi sampling. The distribution of yolk sac diameters and the interpolating growth curve up to 11 weeks of development were analyzed in 239 pregnant women who were delivered of normal infants. The highest visualizing rate of the yolk sac in normal pregnancies was 97 at 7 weeks of gestation. A total of 130 miscarriages occurred before chorionic villi sampling. In these cases, the diameter of the yolk sac versus crown-rump length tended to be larger than found in normal pregnancies. The visualizing rate of the yolk sac in miscarriages after the embryo had been formed was significantly higher in those women who demonstrated fetal heart activity (82.1%) than in those who did not (54.5%). On the other hand, the yolk sac was observed in 44% of miscarriages without a visible embryo. These findings suggest different types of missed abortion. An abnormal karyotype was observed in 23 of 29 chromosomal analyses performed on aborted specimens. An abnormal karyotype was observed in all eight cases with only a yolk sac-like structure within the gestational sac.

Cord sampling for the evaluation of oxygenation and acid-base balance in growth-retarded human fetuses

In 14 pregnancies complicated by intrauterine growth retardation, the umbilical cord was sampled before delivery under ultrasonic guidance for rapid fetal karyotyping. Fetal blood was analyzed for respiratory gases, acid-base balance, and lactate concentrations. Two patients were excluded from the study because cord samples were diluted with amniotic fluid. In six patients (group 1), the clinical assessment warranted continuation of pregnancy. Cesarean sections were performed in the remaining eight patients (group 2) within 8 hours of cord sampling. The data from the two groups were compared with those obtained from umbilical venous blood at the time of elective repeat cesarean section in term appropriate for gestational age infants (controls). No significant difference in PO2 was found between groups 1 and 2 and controls. In contrast, there were significant differences in oxygen saturation and acid-base balance between groups 1 and 2. Lactate concentration was inversely correlated with pH and was elevated in five of six fetuses requiring a prompt cesarean section: In two of these five fetuses, nonstress fetal heart rate tracings were reactive. The results suggest that fetal blood biochemistry, and particularly lactate concentration, may represent an additional indicator of fetal well-being in pregnancies complicated by intrauterine growth retardation.

Outcomes of twin gestations at the University of Colorado Health Sciences Center, 1973-1983

A retrospective study was undertaken of 341 twin pregnancies over a ten-year period at the University of Colorado Health Sciences Center. The perinatal morbidity and mortality were higher than for singleton gestations, but no difference was found between the first and second twins. Bed rest was effective in prolonging gestation and decreasing perinatal mortality (P less than .05). Delivery of the second twin in noncephalic presentation was accomplished vaginally in 46.5%, with external version successful in five of six attempts. The interval between the birth of each twin did not affect outcome.

Respiratory gases, acid-base balance and lactate concentrations of the midterm human fetus

Respiratory gases, acid-base balance, and lactate and hemoglobin concentrations were measured in 14 fetal blood samples between 17 and 21 weeks of gestation. The samples were obtained at the time of fetoscopy performed for prenatal diagnosis. Results have been compared with two reference groups: (a) 4 patients in whom fetal cord blood sampling was performed at 32-36 weeks of gestation, and (b) 10 patients at the time of elective cesarean section, 35-39 weeks. PO2 and oxygen saturations were significantly higher and hemoglobin concentration lower in the mid-gestation fetus. Acid-base balance was not significantly different. There was a significant correlation between maternal and fetal hemoglobin concentrations. The oxygen affinity of fetal blood was not significantly different from that described for term fetuses with a oxygen saturation of less than 90%.

Factors affecting radioactive microsphere measurement of blood flow in pregnant guinea pigs

Comparative blood flow studies were performed in pregnant guinea pigs using radioactive microspheres to test the effects of different sphere sizes on blood flow measurements and the relationship between flows obtained intraoperatively and those performed after 5 days of recovery from anesthesia and surgery. We observed that 1.5% of the cardiac output was shunted through the microcirculation of the carcass, gut, skin and endomyometrium when 15 mu microspheres were used. Intraoperative measurements of heart rate, cardiac output and placental blood flow are significantly lower than measurements made after 5 days recovery. These reductions were ameliorated with the addition of a continuous infusion of isoproterenol and the deletion of atropine from the anesthetic.

Metabolic and circulatory studies of fetal lamb at midgestation

Uterine and umbilical blood flows, the placental clearance of 3H2O, uterine and umbilical uptakes of oxygen, glucose, and lactate were measured in conscious, pregnant sheep at 71-81 days gestation. Fetal weight was 210 +/- 20 g and less than half placental weight. In relation to fetal weight, umbilical flow was 468 +/- 57 ml X min-1 X kg-1, more than double normal values for the mature fetus. Clearance of 3H2O was approximately 12% of the late pregnancy value but high in relation to fetal weight (280 +/- 23 ml X min-1 X kg-1). Fetal oxygen uptake was 10.9 +/- 0.6 ml X min-1 X kg-1, approximately 40% greater than in late gestation. Umbilical uptake of glucose was also relatively high, whereas lactate uptake was low. Uteroplacental tissues consumed more than 80% of the oxygen and glucose taken up by the pregnant uterus. However, uteroplacental utilization rates of oxygen and glucose as well as net lactate production were lower (approximately 50, 30, and 25%, respectively) than in late pregnancy, despite a larger placental mass (486 +/- 22 vs. 302 +/- 12 g).

Protease production by microorganisms associated with reproductive tract infection

Factors influencing pathogenicity of various microbes found in the female lower genital tract remain incompletely understood. Protease production by cervico/vaginal microorganisms may alter or inactivate a variety of proteins important in host defense and structural-functional integrity including collagen-containing chorioamniotic membranes and uterine cervix. Host tissues may be made more susceptible to other organisms' virulence factors by protease-producing members of genital tract local flora. Microorganisms themselves may also be influenced by the presence of other microbial protease. Nonspecific protease, gelatinase, collagenase, and elastase production was examined for in vitro with use of aerobic (30) and anaerobic (25) strains of microorganisms typical of those isolated from the lower genital tract of women with premature rupture of membranes, chorioamnionitis, and puerperal infection. Microorganisms including Bacteroides bivius, Bacteroides melaninogenicus, Bacteroides fragilis, Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Proteus species, and Propionibacterium acnes produce various proteases. Protease production by both acknowledged pathogenic and commensal bacteria may contribute to the occurrence of reproductive tract morbidity including premature rupture of membranes and preterm labor.

Adjunctive erythromycin treatment for idiopathic preterm labor: results of a randomized, double-blinded, placebo-controlled trial

Pathogenesis and optimal treatment and prevention of preterm labor remain incompletely understood. Entry of cervical/vaginal microorganisms into lower uterine tissues has been implicated in preterm labor and may be amenable to specific therapy. Fifty-eight women with less than 34 completed weeks of gestation and without other obstetric complications, who were receiving intravenous tocolytics because of uterine contractions and who had cervical alteration (less than 5 cm dilated), were enrolled in a prospective randomized, double-blinded evaluation of 7 days of adjunctive therapy with enteric-coated erythromycin base (333 mg three times daily by mouth) versus placebo. Microbiologic examination included cultures for Neisseria gonorrhoeae, Chlamydia trachomatis, and group B streptococcus. Fifty-eight women with singleton pregnancies (29 erythromycin; 29 placebo) completed the protocol. Among women with cervical dilatation greater than or equal to 1 cm at the beginning of treatment, mean time until delivery was 32.5 days with erythromycin and 22.4 days with placebo treatment (p = 0.027). Of the erythromycin-treated women, seven of eight were delivered at greater than or equal to 37 weeks and only three of nine placebo-treated women were delivered at greater than or equal to 37 weeks (p = 0.035). Orally administered enteric-coated erythromycin as adjunctive treatment of pregnant women in labor less than or equal to 34 weeks is well tolerated. Adjunctive erythromycin given to women treated for preterm labor less than or equal to 34 weeks is associated with prolongation of pregnancy and delivery at 37 weeks only in women with cervical dilatation at the beginning of treatment.

Relationship between metabolic rate and body size in fetal life

To define the O2 consumption rate (VO2) versus body mass relation during fetal growth, we compared fetal sheep VO2 at mid and late gestation. VO2 per kg wet weight was 37% higher at mid gestation. However, VO2 per kg dry weight was 2.5 times higher, and associated with a high viscera/body weight ratio. Fetal VO2 tends to grow proportionally to body mass because marked decreases in the relative growth of visceral organs and in the VO2/dry weight ratio are accompanied by a decrease in body water.

Umbilical cord prolapse

Umbilical cord prolapse complicated one of 385 pregnancies occurring at the University of Colorado Health Science Center between 1969 and 1982. Whereas malpresentation of the fetus is frequently associated with prolapse of the funis, nearly 50% of all cases occurred in vertex presentations. Obstetric intervention is associated with nearly one in five cases of cord prolapse and represents a readily preventable cause of maternal and perinatal morbidity.

Comparison of fetal and maternal hind limb metabolic quotients in sheep

This study compared substrate utilization by the fetal hind limb and the maternal hind limb in 26 sheep at 120 to 135 days of gestation. Catheters were placed in the mother and the fetus to sample femoral arterial and venous blood by use of a nonocclusive technique. Arterial and venous concentrations of oxygen content, glucose, lactate, acetate, and ketoacids were measured simultaneously and were used to calculate metabolic quotients. The fetal hind limb was perfused with arterial blood having a lower oxygen content than the maternal hind limb (3.03 +/- 0.17 versus 4.94 +/- 0.24 mmol/L, p less than 0.001) and had a smaller arteriovenous difference of oxygen content (0.97 +/- 0.05 versus 2.68 +/- 0.104 mmol/L, p less than 0.001). Despite a lower fetal arterial glucose concentration (0.81 +/- 0.05 versus 2.58 +/- 0.13 mmol/L, p less than 0.001), the glucose/oxygen quotient (0.82 +/- 0.05 versus 0.20 +/- 0.02, p less than 0.001) and the arteriovenous difference of glucose (0.13 +/- 0.01 versus 0.08 +/- 0.01 mmol/L, p less than 0.001) were higher in the fetal hind limb than in the maternal hind limb. Both limbs were net producers of lactate. The (glucose + lactate)/oxygen quotient was also higher in the fetal hind limb than in the maternal hind limb (0.68 +/- 0.05 versus 0.12 +/- 0.04, p less than 0.001). In the maternal hind limb, acetate and ketoacids uptake could account for 48% +/- 6% of total oxygen consumption whereas in the fetal hind limb it accounted for only 12% +/- 4% (p less than 0.001). The data demonstrate that, in relation to oxygen uptake, fetal hind limbs have approximately a 2.8% higher rate of perfusion and take up approximately four times as much glucose as the hind limbs of the mother in the resting state.

The effect of a leukotriene receptor antagonist, FPL 55712, on estrogen-induced uterine hyperemia in the nonpregnant rabbit

Estrogen results in delayed uterine hyperemia. We postulate that the leukotrienes may be the mediators of the uterine vascular responses to estrogen. To test this hypothesis, we gave FPL 55712, a selective leukotriene antagonist, to estrogen-primed, nonpregnant rabbits and measured regional blood flows by the radioactive microsphere technique. In 10 chronically catheterized animals, blood flows were measured in the control condition (C), and again 2 hours after systemic administration of estradiol (EST). Thirty minutes before administration of estradiol, five animals received systemic FPL 55712, whereas five animals received vehicle only. The vehicle group showed the expected increase in uterine blood flow from 0.62 +/- 0.1 to 2.72 +/- 0.4 ml X min-1 X gm-1, and decrease in uterine resistance from 144 +/- 31 to 34 +/- 8 peripheral resistance units (PRU) X gm, with a resistance ratio (estradiol/C) of 0.23 +/- 0.01. Unexpectedly, the FPL 55712 group showed a further increase in uterine blood flow from 0.66 +/- 0.1 to 4.60 +/- 0.3 ml X min-1 X gm-1, and a decrease in resistance from 133 +/- 25 to 17 +/- 1 PRU X gm, with a resistance ratio of 0.13 +/- 0.02. The leukotriene antagonist FPL 55712 potentiates estrogen-induced uterine hyperemia by 77% (P less than 0.001). These data suggest that leukotrienes do not mediate, but rather inhibit, the uterine vascular responses to estrogen.

The antepartum assessment of fetal well-being

Modern obstetrics is concerned with the health and well-being of both the mother and the unborn child. During the first two thirds of this century there was a pronounced decrease in maternal mortality and morbidity related to pregnancy. More recently, using the techniques of amniocentesis, antepartum fetal heart rate testing and ultrasound, obstetricians have been able to more accurately assess the health of a fetus. This knowledge has resulted in decreased perinatal mortality and morbidity and, when rigorously applied, a decrease in fetal loss.

Relationship between placental blood flow and placental and fetal size in guinea pig

Blood flow measurements were made using radioactive microspheres in 14 unstressed, conscious, pregnant guinea pigs with gestational age ranging between 34 and 67 days. Within each litter placental blood flow (PBF) was positively correlated to fetal weight (FW), even after correcting for placental weight differences. Although the largest littermate was, on the average, only 30% larger than the smallest, its material placental blood flow was 95% greater. The PBF vs. FW relationship could be described by the allometric equation: PBF = Ai FW2.89 where Ai is a litter-specific coefficient. This study demonstrates that the placenta of the largest littermate is "hyperperfused" compared with its smaller siblings.

Endometrial carcinoma: clinical-pathologic comparison of cases in postmenopausal women receiving and not receiving exogenous estrogens

Clinical and pathologic findings were compared in 43 postmenopausal endometrial carcinoma patients who had received exogenous estrogens prior to diagnosis and 79 similar patients unexposed to estrogens. Estrogen non-users were more likely to manifest lower parity, later menopause, obesity, hypertension, and diabetes, all of which have been considered to be constitutional risk factors for the development of endometrial carcinoma. Although estrogen users and non-users had similar extent of disease as judged by clinical stage, there was a tendency to more myometrial invasion in hysterectomy specimens from non-users, as well as greater frequency of unfavorable histologic types and grades of tumor. At short-term follow-up, more recurrences occurred in non-users, and this tendency appeared to be independent of clinical stage, histologic type, histologic grade, or modality of treatment. The significance of these and other observation to the determination of the risk-benefit ratio for estrogen administration is discussed.

Redistribution of cardiac output and oxygen delivery in the hypoxemic fetal lamb

In hypoxia, fetal cardiac output and the product arterial O2 content x blood flow to the fetal heart and central nervous system (CNS) tend to remain constant. As a consequence the percentage of cardiac output directed to the heart and CNS increases hyperbolically in inverse relation to the oxygen content of the fetal ascending aorta, [O2]as. The fetal lamb maintains [O2]as approximately 0.45 mM (0.45 +/- 0.02 SEM) higher than the O2 content in the abdominal aorta, [O2]ab, over a wide range of oxygenation. When [O2]as decreases below the 2 mM level, the [O2]as--[O2]ab difference (delta O2) decreases also. A mathematical model of the fetal circulation shows that delta O2 is a function of the ratio oxygen consumption of fetal upper body/abdominal aorta blood flow (VU/FA). The behavior of delta O2 in hypoxia can be explained by assuming that the VU/FA ratio is maintained in moderate hypoxia and decreases in sever hypoxia.

Blood flow to fetal organs as a function of arterial oxygen content

In a sheep preparation the blood flow to fetal organs was studied 3 to 10 days after surgery by means of the microsphere technique over a range of fetal arterial O2 content from 6 to 1 mM. Blood flows to neural tissues (cerebrum, cerebellum, brain stem), heart, and the adrenals increased in inverse relation to arterial O2 content. As a result the arterial supply of O2 to these organs tended to remain constant over the O2 range studied. Blood flow to the fetal lungs decreased progressively with hypoxia. The blood flow to kidneys, digestive tract, pancreas, and carcass had a tendency to remain constant or increase gradually in the transition from high to moderately low levels of arterial O2 content and then to decrease abruptly in more severe hypoxia. Umbilical blood flow did not change systematically in relation to arterial O2 content.

Utilization of gyniatricians as primary health care providers for women

The role, functions, activities, educational preparation and relationship with other health professionals of a new type of primary health care provider is described. The name gyniatrician has been applied to this kind of physician, who will be qualified to provide overall primary health care for women from the onset of puberty through adult life.

Regulation of cerebral blood flow in the ovine fetus

The effects on fetal cerebral blood flow (Qc) of changes in the carotid arterial and sagittal sinus venous PO2, PCO2, and oxygen content were studied in the chronically catheterized ovine fetus in utero at 130-140 days of gestation. Forty-seven measurements of Qc were made in 20 fetuses with radioactive microspheres. In 11 of these animals, 84 measurements of cerebral arteriovenous differences of oxygen content were performed, permitting an indirect measurement of cerebral blood flow (Qc*), assuming a constant cerebral metabolic rate. Arterial and, in 11 animals, sagittal sinus blood was withdrawn for analysis of PO2, PCO2, oxygen content, and pH at the time of the flow measurements. Preliminary analysis showed the best predictor of Qc and Qc* to be the reciprocal of the arterial oxygen content (1/CaO2). Multiple linear regression analysis combining the effects of 1/CaO2 with arterial PCO2 (PaCO2) gave the following equations: Qc = 458.8 (1/CaO2) + 2.68 PaCO2 - 107.93 (R2 = 0.68); Qc* = 435.54 (1CaO2) + 2.20 PaCO2 - 75.03 (R2 = 0.86). As a result of the hyperbolic relationship between Qc (and Qc*) and CaO2, changes in CaO2 at the low levels found during intrauterine life exert an important influence on the fetal cerebral circulation.

Cryocoagulation of the endometrium at the uterine cornua

A cryoprobe that will produce coagulation necrosis and subsequent scar formation of the cornual areas of the uterus has been tested. A discussion is made of the developmental program, including the design of the instrument, efficacy and safety testing in baboons, and preliminary investigations of the safety of this procedure in man.

Fetal cerebral oxygen consumption at different levels of oxygenation

Cerebral oxygen consumption (VCO2) was measured in 10 unanesthetized, chronically catheterized fetal sheep at 130-140 days of gestation. The VCO2 was calculated using cerebral blood flow (QC) measured with radioactive microspheres and the cerebral arteriovenous difference of O2 content (C(a-V)O2) calculated from preductal arterial and sagittal sinus venous blood. The ewe was exposed to varying concentrations of oxygen, resulting in fetal arterial oxygen contents (CaO2) of 0.89-5.58 mM, arterial oxygen tension (PaO2) values of 14-36 Torr, and cerebral venous oxygen tension (PVO2) values of 9-25 Torr. Although there was a clear relationship between the fetal CaO2 and C(a-V)O2, this was shown to be the result of changes in Qc rather than changes in VCO2. There was not a statistically significant correlation between either CaO2 or PVO2 and VCO2 over this range of oxygenation. On the other hand, C(a-V)O2 was highly correlated with Qc. There is no evidence that VCO2 is a function of oxygen tension (PO2) in the unanesthetized fetal sheep as long as the sagittal sinus PO2 is greater than or equal to 9 Torr.

Endometrial carcinoma in women under 40 years of age: comparison of cases in oral contraceptive users and non-users

Women under 40 years of age rarely develop carcinoma of the endometrium, this age group comprising less than 3% of all cases in most large series. The Registry for Endometrial Carcinoma in Young Women Taking Oral Contraceptive Agents has recorded and studied 30 cases in women under 40 with a history of oral contraceptive administration, and these are compared with 25 cases in the same age group which were accessioned at the Armed Forces Institute of Pathology prior to the era during which these agents have been available, and with series reported in the literature totaling 137 cases with no contraceptive history. In the first group, special attention is paid to the 20 women who received sequential agents exclusively or predominantly, since the association with these agents (primarily Oracon) is much higher than would be expected from the fact that less that 10% of oral contraceptives used in this country are of the sequential type. An analysis of the three groups reveals a similar incidence of the various histologic types (primarily well differentiated tumors with a relatively favorable prognosis), the only difference being the presence of secretory features in 14 of 29 oral contraceptive users vs. only two of 25 women not taking these agents. Clinical and pathologic staging were also predominantly favorable, and comparable in all groups. There were, however, notably higher incidences of nulliparity, obesity, and sclerocystic ovaries--all features traditionally associated with endometrial carcinoma--in the patients not receiving oral contraceptives or receiving combined agents, suggesting that the group receiving sequentials may not represent the same constitutionally predisposed population. Only three of 55 women among our personally reviewed cases have thus far died of cancer (one in the contraceptive group and two in the non-user group) and all three of these had poorly differentiated tumors with myometrial invasion. The excellent prognosis for most patients in this age group is thus confirmed.

The effect of various vasoactive compounds upon the uterine vascular bed

The effects of various vasodilators on the uterine vascular bed were investigated in nonpregnant, oophorectomized sheep with chronically implanted flow probes and catheters inserted into branches of the uterine arteries. A 1 mug dose of estradiol-17beta (0.224 muM) produces a maximum uterine blood flow response after intra-arterial injection. Adenosine (24 muM) and bradykinin (0.02 muM) were observed to increase blood flow to levels achieved by 1 mug of estradiol-17beta. Acetylcholine, isoproterenol, and histamine were less potent in their vasodilator activity. Atropine, propanolol, and diphenhydramine did not inhibit the increase of uterine blood flow induced by estrogens.

Effect of estradiol-17beta on blood flow to reproductive and nonreproductive tissues in pregnant ewes

The effect of estradiol-17beta (1 mug per kilogram) on regional blood flow and cardiac output was studied by means of radionuclide-labeled microspheres in 6 nonpregnant and 13 pregnant ewes five to seven days after operation. Estradiol caused vasodilation in myometrium, endometrium, and placental cotyledons throughout pregnancy, but these responses were significantly less than the fifteenfold increase seen in the nonpregnant uterine tissues. Significant vasodilation also occurred in the ovaries, cervix, vagina, uterine tubes, mammary gland, skin, and adrenal glands of pregnant ewes. Cardiac output increased by 14%. No significant change in uterine oxygen consumption was associated with the increase in blood flow to the pregnant uterus.

Mammary blood flow and endocrine changes during parturition in the ewe

The temporal relationship between changes in mammary blood flow (MBF) and changes in the concentration of plasma prolactin, progesterone, estradiol-17beta, and cortisol, was examined in chronic sheep preparations undergoing spontaneous labor (Group I) or labor induced by an infusion of dexamethasone (1 mg/24 h) to the fetus (Group II). In Group I, an increase in prolactin (45 to 489 ng/ml), a decrease in progesterone (15 to 4 ng/ml), and an increase in MBF (97 to 365 ml/min) occurred at about the same time, whereas increases in estradiol-17beta (80 to 211 pg/ml) and cortisol (9 to 39 ng/ml) followed the change in MBF. A similar pattern of changes in MBF and hormonal concentrations occurred over a shorter period when premature labor was induced in the animals in Group II. These findings suggest that changes in plasma prolactin and progesterone concentrations play an important role in the regulation of MBF at the time of parturition.

Endometrial carcinoma in young women taking oral contraceptive agents

The first 21 cases recorded in the Registry for Endometrial Carcinoma in Young Women Taking Oral Contraceptive Agents are reported. We have found no other such cases in the literature, and indeed several authors have stated that these agents, because of their predominantly progestional action, would be expected to be protective against this disease. In 8 of the 21 patients, factors were present which militated against a close relation between oral contraceptives and carcinoma, and 5 of these 8 patients had taken only or predominantly combined agents. On the other hand, 11 of the remaining 13 patients took sequential agents, a ratio directly opposite that of the usage of combined and sequential agents in the American population. The possible reasons for the excess of sequential agents, chiefly Oracon, are discussed, and directions for future study are suggested.

Relationship of mammary blood flow to parturition in the ewe

Mammary blood flow was measured in conscious, unanesthetized ewes with electromagnetic flow probes prior to spontaneous labor (four animals) or during the induction of premature labor (four animals) by administration of dexamethasone, 1 mg/24 h, to the fetus. In all animals an increase in mammary blood flow was noted prior to delivery. Dexamethasone administered to one mother in the same dose did not induce labor or produce an increase in mammary blood flow. These results suggest that the fetal adrenal gland influences maternal mammary blood flow prior to delivery.

Cerebral metabolism in sheep: a comparative study of the adult, the lamb, and the fetus

The cerebral uptakes of glucose, oxygen, lactate, pyruvate, acetoacetate and beta-hydroxybutyrate were compared in the adult, the fetal, and the newborn sheep. Beginning 1-2 days after surgery, we withdrew samples simultaneously from an artery and from the sagittal sinus for up to 2 wk. At all ages glucose was the only substrate taken up in significant quantity relative to oxygen. The glucose-oxygen quotients were 0.98 less than 1.03 less than 1.08 in adults; 0.92 less than 0.99 less than 1.06 in lambs; 0.92 less than 0.98 less than 1.03 in fetuses. These quotients were not significantly different. There was a significant (P less than .05) arteriovenous difference for lactate in the adult (-0.031 mM), but not in the lamb or fetus. A significant (P less than .05) arteriovenous difference pyruvate was found in the adult (-0.013 mM) and in the fetus (-0.020 mM). The findings of a glucose-oxygen quotient of approximately 1 and the lack of significant lactate production in fetal sheep brain are consistent with the hypothesis that anerobic glycolysis is unimportant to the steady-state cerebral metabolism of the fetal sheep.

The effect of actinomycin D on estrogen-induced uterine blood flow

The effect of actinomycin D on estrogen-induced uterine blood flow was studied in four nonpregnant, oophorectomized sheep, utilizing electromagnetic flow probes chronically implanted around the uterine arteris. Two hours after the intravenous injection of 1 mug of estradiol-17beta per kilogram of body weight, incorporation of [3H]-uridine into RNA was two- to threefold higher (2.7 plus or minus 0.4 S.E.M.) in the control horn than the uterine horn that had received an intra-arterial injection of actinomycin D. Actinomycin D had no effect on the estrogen-induced increase in uterine blood flow.

Cord blood coagulation studies in infants of high-risk pregnant women

A prospective study of cord blood for coagulability, evidence for disseminated intravascular coagulation (DIC), and hematocrit was done in 106 infants who were offspring of mothers with high-risk pregnancies (pre-eclampsia, diabets mellitus, third-trimester bleeders, severe erythroblastosis fetalis, maternal hypertension, fetal distress, and spontaneous premature labor). Significant changes of hypercoagulability (low AT-III and abnormal TEG) were seen in the third-trimester bleeder and premature labor groups which also had the highest incidence of IRDS and necrotizing. Infants undergoing "stress" (pre-eclampsia, fetal distress) had elevated levels of factors V and VIII but were not hypercoagulable or AT-III deficient. Except for mild thrombocytopenia, infants of the diabetic mothers, a group with increased thrombotic complications, did not show any cord blood abnormalities. Offspring of third-trimester bleeders were anemic. The EBF infants were also anemic, severely hypercoagulable, and showed coagulation changes compatible with severe liver disease and/or DIC. Mild changes compatible with intravascular coagulation were seen in six infants and were not related to the the development of IRDS.

The glucose/oxygen quotient of the term human fetus

Glucose/oxygen quotients were obtained at repeat elective cesarean section from appropriately grown, normoxemic term human fetuses. The mean glucose/oxygen quotient for these 11 fetuses was 0.81. Umbilical arterial glucose concentration and the maternal-fetal glucose concentration gradient were found to be functions of the maternal venous glucose concentration. Umbilical blood samples obtained following labor and vaginal delivery may not represent the normal metabolism of the fetus prior to the onset of labor. Similarly, samples obtained at cesarean section may not be representative if fetal hypoxemia associated with transient maternal hypotension occurs.

Growth of uterine oxygen and glucose uptakes during pregnancy in sheep

The growth of uterine oxygen and glucose uptakes (Qo₂, Q glucose) throughout pregnancy was determined in sheep with chronically implanted uterine artery electromagnetic flow probes and arterial and uterine venous catheters. The flow probe measurements were corrected to total uterine blood flow by means of an equation based on simultaneous flow probe and radioactive microsphere determinations. Uterine Qo₂, and Q glucose increased logarithmically as gestation progressed. During the last third of gestation, the mean Qo₂ for twin pregnancies was 44<i>%</i> higher than Qo₂ for single pregnancies. In the last 3 weeks of gestation the uterine glucose/oxygen quotient was 0.76 (95<i>%</i> confidence limits 0.65–0.87), which is significantly less than one and significantly greater than the 0.46 umbilical glucose/oxygen quotient determined in previous studies. This result indicates that substrates other than glucose are used in large amounts in order to satisfy the requirements of uterine oxidative metabolism in late pregnancy and that the placenta has a relatively high glucose/oxygen quotient. Uterine arteriovenous differences of fructose and pyruvate measured at intervals throughout gestation revealed that there is no significant uptake of these substrates by the pregnant uterus.

Circulatory changes in the reproductive tissues of ewes during pregnancy

The blood flows to reproductive organs were measured by means of radionuclide-labeled microspheres in 24 pregnant ewes with gestational ages ranging from 38 to 141 days. The microspheres were injected in the left ventricle of the non-anesthetized animal 4–7 days after surgery and while uterine blood flow was recorded continously by means of electromagnetic probes on both uterine arteries. The blood flow to ovaries with corpus luteum was maximum in early pregnancy and greater than in ovaries without corpus luteum. Placental blood flow increased from &#8764;30 to &#8764;300 ml/min during the stage of placental growth (40–90 days). In the last 50 days of pregnancy placental weight declined, whereas placental flow continued to rise and attained &#8764;1,500 ml/min near term. The growth curves of fetal weight and placental blood flow followed a similar pattern, but the early increase in placental flow was more rapid than the increase in fetal weight. Hence placental flow per gram of fetus was larger in early pregnancy (&#8764;9 ml/min&#183;g) than near term (&#8764;0.25 ml/min&#183;g). In twin pregnancies the placenta of each fetus received a smaller blood flow than the placenta of a singleton of comparable age. Mammary blood flow demonstrated no change until the last 60 days, when it increased from &#8764;10 to &#8764;200 ml/min. This phenomenon coincided with an increase in mammary weight and the final progressive increase of placental blood flow.