Fetal erythropoietin levels in pregnancies complicated by meconium passage: does meconium suggest fetal hypoxia?

OBJECTIVE

We sought to determine whether umbilical cord plasma erythropoietin levels were different in deliveries complicated by meconium passage and to determine whether this response is influenced by gestational age.

STUDY DESIGN

Fetal erythropoietin levels were measured in 203 appropriately grown neonates at 37 to 43 weeks of gestation; among those, 70 had passed meconium.

RESULTS

Meconium passage in the entire population was associated with elevated fetal erythropoietin levels (68 vs 31 mIU/mL; P <.001). Cord blood gases, pH, base deficit, and PO (2), as well as the 1- and 5-minute Apgar scores, were not different between the meconium and no-meconium groups. Gestational age and birth weights were significantly higher in the meconium group. Stepwise multiple regression analysis with meconium and gestational age used as the independent variables showed both meconium and gestational age to be independently associated with fetal erythropoietin levels (r = 0.356, F = 14.5; meconium, P <.001; gestational age, P <.01).

CONCLUSIONS

These results suggest that meconium passage can be associated with chronic fetal hypoxia as demonstrated by elevated fetal erythropoietin levels, independent of gestational age.

Human uterine leiomyomata express higher levels of peroxisome proliferator-activated receptor gamma, retinoid X receptor alpha, and all-trans retinoic acid than myometrium

Uterine leiomyomata are the main indication for a hysterectomy in the United States and occur in 25% of women >35 years. Because uterine leiomyomata can form when ovariectomized guinea pigs are exposed to estradiol and retinoic acids, we tested whether human leiomyomata had high levels of retinoic acids and related nuclear receptors. Compared with normal human myometrium, leiomyomata had 3- to 5-fold higher levels of peroxisome proliferator-activated receptor gamma (PPARgamma), retinoid X receptor alpha proteins, and all-trans retinoic acid, but only during the follicular phase of the menstrual cycle. 9-cis Retinoic acid was undetectable in either leiomyomata or myometrium. PPARgamma mRNA levels were lower in leiomyomata than myometrium, but only during the luteal phase of the cycle. A PPARgamma agonist, troglitazone, was given to guinea pigs along with estradiol and all-trans retinoic acid and produced the largest leiomyomata seen to date in this model. By contrast, no tumors formed when troglitazone was given alone or with estradiol or when troglitazone was given with estradiol and 9-cis retinoic acid. New therapies for human leiomyomata may emerge by combining antagonists for PPARgamma and retinoid X receptor alpha with selective estrogen receptor modulators.

Fetal erythropoietin levels in growth-restricted and appropriately grown neonates with and without abnormal fetal heart rate tracings: a comparison with cord blood gases and Apgar scores

OBJECTIVE

To determine if umbilical cord plasma erythropoietin (EPO) levels in combination with cord blood gases and Apgar scores can distinguish between subacute and chronic uteroplacental insufficiency.

METHODS

A total of 184 neonates delivered between 1993 and 1997 at Tampa General Hospital were studied. Cord plasma EPO levels, cord blood gases, and Apgar scores were determined prospectively and compared in four subgroups that were defined based on the presence or absence of fetal growth restriction (FGR; chronic fetal hypoxia), abnormal fetal heart rate tracings during labor (FHR; subacute/acute fetal hypoxia), or both.

RESULTS

Both growth-restricted and appropriately grown newborns with abnormal intrapartum FHR tracing had elevated umbilical cord plasma EPO (183.5 and 135.2 mIU/ml, respectively; normal = 20.7 mIU/ml) and base deficit, whereas pH, Po2, and 1-minute and 5-minute Apgar scores were significantly lower, compared with appropriately grown newborns with a normal intrapartum course. Among newborns with normal heart rate tracings and FGR, the mean plasma EPO levels were elevated (89.5 mIU/ml), whereas the other parameters were not different from normal.

CONCLUSION

Our findings suggest that, although cord blood gases and Apgar scores may reflect subacute and acute events, they are not good predictors of chronic uteroplacental insufficiency. The supplemental use of umbilical cord plasma EPO levels may improve our ability to identify chronic uteroplacental insufficiency.

Are maternal diabetes and preeclampsia independent simulators of fetal erythropoietin production?

To determine if diabetes and preeclampsia are independent stimulators of erythropoietin, distinct from hypoxia, we measured umbilical cord plasma erythropoietin in 239 deliveries from 24 to 40 weeks of gestation. Mean plasma erythropoietin levels were not different between normal, diabetic, and preeclamptic women when all deliveries were analyzed. When infants with suspected intrauterine hypoxia were excluded, the mean erythropoietin level was considerably lower within all three groups but there was no difference among the groups. In suspected hypoxia, the mean fetal erythropoietin was elevated, but there was no difference between control, diabetic, or preeclamptic pregnancies. These results provide further support that hypoxia remains the only known stimulator of erythropoietin production in the fetus.

Modulation of the prostaglandin E receptor: a possible mechanism for infection-induced preterm labor

OBJECTIVE

To evaluate the modulatory effects of interleukin (IL)-1beta and prostaglandin (PG)E2 on the PGE2 receptor subtype EP1 in amnion cell cultures.

METHODS

Amnion cell cultures were incubated in increasing concentrations of (IL)-1beta or PGE2. Cultures were also incubated in high concentrations of IL-1beta and PGE2 in combination. Changes in EP1 receptor levels were evaluated by western and northern blot analysis. Culture fluid PGE2 levels were measured by enzyme-linked immunosorbent assay.

RESULTS

EP1 receptor protein levels decreased with increasing levels of PGE2 (r = -0.82, P < .05). EP1 receptor protein (r = 0.95, P < .05), EP1 mRNA (r = 0.95, P < .01), and culture fluid PGE2 levels (P < .01) were all increased after IL-1beta administration. EP1 receptor levels also increased approximately fourfold in response to IL-1beta incubation even in the presence of high agonist (PGE2) concentrations (P < .01).

CONCLUSION

The results of this study show that IL-1beta might be involved in infection-induced preterm labor by interfering with the normal regulation of EP1 receptor levels and with the promotion of increased PGE2 production in amnion tissue.

Tumor necrosis factor-alpha upregulates the prostaglandin E2 EP1 receptor subtype and the cyclooxygenase-2 isoform in cultured amnion WISH cells

Recent studies have demonstrated a strong correlation between infection and preterm labor. Preterm delivery is also associated with high levels of cytokines and prostaglandins in amniotic fluid. The purpose of this study was to investigate the effect of tumor necrosis factor-alpha (TNF-alpha) on the levels of cyclooxygenase, prostaglandin E2 production (PGE2), and expression of the PGE2 receptor subtype EP1 in amnion WISH cell culture. Amnion WISH cell cultures were incubated in increasing concentrations of TNF-alpha (0-50 ng/ml). Changes in cyclooxygenase and EP1 receptor proteins were evaluated by Western blot analysis. Changes in EP1 mRNA were evaluated by Northern blot, and culture fluid concentrations of PGE2 were estimated by enzyme immunoassay (EIA). EP1 protein (p<0.01), EP1 mRNA (p<0.05), cyclooxygenase-2 (COX-2) protein (p<0.001), and PGE2 concentrations (p<0.01) all increased with increasing concentrations of TNF-alpha. Changes in COX-1 protein were not observed following TNF-alpha-incubation. The results suggest that TNF-alpha may play a role in infection-induced preterm labor by its pleiotropic ability to simultaneously stimulate COX-2 activity, PGE2 concentrations, and PGE2 EP1 receptor levels in human amnion.

Effects of raloxifene in a guinea pig model for leiomyomas

OBJECTIVE

Chronic exposure of oophorectomized guinea pigs to 17beta-estradiol causes leiomyoma formation. Our aims were to determine whether these leiomyomas can become estradiol independent after exposure to estradiol and if raloxifene inhibits leiomyoma growth when given concomitantly with estradiol.

STUDY DESIGN

To induce leiomyoma development, 6 oophorectomized animals received two estradiol implants for 140 days. Next, the estradiol implants were replaced with empty implants in 3 animals, whereas the other 3 received 2 new estradiol implants and raloxifene given per os 10 mg/kg per day for 60 days. Tumor size was monitored biweekly by ultrasonography.

RESULTS

On estradiol removal, abdominal wall leiomyomas regressed within 15 to 30 days; when estradiol implants were reintroduced, leiomyomas redeveloped. Within 30 days on raloxifene, all abdominal leiomyomas (n = 9) regressed as determined by ultrasonography and verified at laparotomy. Serum raloxifene and estradiol levels were 432 +/- 46 pg/mL and 78 +/- 13 pg/mL (mean +/- SEM, n = 3), respectively, after 60 days of treatment.

CONCLUSIONS

Leiomyomas did not become estradiol independent, even after long exposure to estradiol; ultrasonography allowed frequent, noninvasive assessment of leiomyoma size, and raloxifene rapidly regressed leiomyomas in this animal model.

Elevated umbilical cord plasma erythropoietin levels in prolonged pregnancies

OBJECTIVE

To determine if umbilical cord plasma erythropoietin levels are elevated in pregnancies that continue beyond their expected date for delivery.

METHODS

Erythropoietin was measured using an enzyme-linked immunosorbent assay in 124 appropriately grown newborns delivered from 37-43 weeks' gestation. Each woman had an uncomplicated labor and delivery course without evidence of fetal stress or meconium. The comparison was made between pregnancies ending at 37-40 weeks' gestation and those at 41-43 weeks' gestation.

RESULTS

There was no difference between the two groups in cord blood gases or Apgar scores at 1 and 5 minutes. Cord plasma erythropoietin levels were significantly higher in pregnancies delivered after 41 completed weeks' gestation (41 or more weeks: 48.0+/-7.1 mIU/mL, n=45 versus 37-40 weeks: 26.1+/-4.2 mIU/mL, n=79, P < .001). When compared with pregnancies delivered between 37 and 40 weeks, erythropoietin levels were significantly elevated in pregnancies delivered at either 41, 42, or 43 weeks' gestation.

CONCLUSION

In pregnancies reaching 41 weeks and beyond, cord plasma erythropoietin levels are significantly increased, indicating altered fetal oxygenation in some of these pregnancies. These results support the current practice of close fetal surveillance of prolonged pregnancies.

Umbilical cord plasma erythropoietin levels in pregnancies complicated by maternal smoking

OBJECTIVE

Our goal was to determine whether maternal smoking was associated with elevated umbilical cord erythropoietin, a marker for chronic hypoxia.

STUDY DESIGN

Plasma erythropoietin levels were measured in umbilical cord plasma of 222 newborns. There were 48 mothers who smoked and 174 nonsmokers.

RESULTS

When all pregnancies were included, mean cord plasma erythropoietin levels were significantly higher in the smokers (78.0 +/- 15.3 mIU/ml) compared with the nonsmoking group (35.2 +/- 4.0 mIU/ml; p < 0.005). Regression analysis showed a significant positive correlation between the number of cigarettes smoked per day and cord plasma erythropoietin levels (r = 0.26, p < 0.0001). Smoking was associated with a significantly elevated risk (relative risk = 2.6, 95% confidence interval 1.7 to 10.9, p < 0.005) of fetal growth restriction. When pregnancies with fetal growth restriction were excluded from the analysis, the difference between the two groups remained significant (smokers 81.3 +/- 18.6, n = 38; nonsmokers 24.3 +/- 1.4, n = 164; p < 0.03).

CONCLUSIONS

These results illustrate that smoking during pregnancy is associated with fetal growth restriction and significantly elevated umbilical cord erythropoietin levels.

The effect of interleukin-1 beta and interleukin-4 on the expression of prostaglandin receptors EP1 and EP3 in amnion WISH cells

PROBLEM

Although prostaglandin E2 (PGE2) is believed to modulate biochemical and immunological events leading to parturition, the role of prostaglandin E receptors during labor has not been investigated.

METHOD OF STUDY

Amnion WISH cells were incubated in media containing increasing concentrations of either interleukin-1 beta (IL-1 beta) or IL-4. Increased EP1 and EP3 protein expression was determined by Western blot analysis with peptide-specific antibodies. Concomitant measurements of culture media PGE2 were made by an enzyme immunoassay.

RESULTS

Incubation of WISH cells with IL-1 beta or IL-4 caused a two- to three-fold increase in EP1 protein levels. IL-1 beta and IL-4 also caused six- and two-fold increases, respectively, in culture fluid PGE2 concentrations. IL-1 beta or IL-4 had no effect on EP3 protein levels.

CONCLUSIONS

Based on these results, it is proposed that IL-1 beta and IL-4 may be involved in the initiation and promotion of labor by inducing EP1 levels and PGE2 production in amnion.

Umbilical plasma erythropoietin correlations with blood gases and gestational age in appropriately grown infants

Erythropoietin (EPO) levels were measured using an ELISA method in umbilical cord plasma from 68 appropriately grown neonates at 27 to 43 weeks of gestation (EGA). A consistent but small (5%) difference was found between the EPO levels in the umbilical artery (Ua), 21.0 +/- 2.5 mlU/mL (mean +/- SEM), and umbilical vein (Uv), 22.0 +/- 2.7 mlU/mL (p < 0.02, n = 30). Significant inverse correlations were found between Ua EPO levels and pO2 (r = -0.44, p < 0.002), pH (r = -0.68, p < 0.0001), as well as base deficit (r = -0.56, p < 0.0001). A significant correlation was found between EGA and Ua EPO from 27 to 43 weeks of gestation (r = 0.45, p < 0.001, n = 68). One and 5 minute Apgar scores did not correlate with EPO. These findings indicate that EPO correlates strongly with cord gas parameters and thus may serve as a clinically useful marker for both subacute fetal distress and chronic uteroplacental insufficiency.

Estrogen-induced guinea pig model for uterine leiomyomas: do the ovaries protect?

A guinea pig model was used to study the hormonal control of uterine leiomyomas. Twenty female guinea pigs were divided into four groups--young, old, ovariectomized (OVX), and non-OVX animals--and were given two estradiol-17 beta (E2) silastic implants each for 3-10 mo; another four older OVX animals served as controls and received empty implants. After 3 mo, 100% (8 of 8) of the OVX animals, but none of the OVX controls, developed tumors, mainly on the uterine serosa and the abdominal wall. Electron microscopy and desmin immunostaining demonstrated that the tumors were leiomyomas. In E2-treated animals, E2 levels in serum, leiomyomas, or leiomyoma-free uterine segments rose significantly while serum progesterone (P4) was negligible. Surprisingly, only 8% (1 of 12) of the non-OVX animals developed a tumor. This apparent "ovarian protection" was transient: after 6-9 mo, 50% of the remaining non-OVX animals developed leiomyomas, but these were smaller and fewer than in OVX animals. On the basis of this model, we propose the hypothesis that some factors from the ovaries suppress leiomyoma growth in response to estrogen but that as the ovaries age this protection is diminished, allowing the clinical development of leiomyomas.

Carbohydrate metabolism studies after one year of using an oral contraceptive containing gestodene and ethinyl estradiol

The objective of the study is to evaluate the effects of a gestodene-containing oral contraceptive on carbohydrate metabolism. The design of the study is prospective. The setting is at University of South Florida Outpatient Unit. The patients consisted of twenty-three normal women desiring contraception. Serum glucose and insulin levels were measured during a three-hour glucose tolerance test at control time and after one year of drug use.

RESULTS

All of the one-year glucose values were significantly elevated as well as the fasting and three-hour insulin values. These changes were mostly confined to women over 26 years of age and not in the younger 18 to 23 year olds. An oral contraceptive containing 75 micrograms of gestodene and 30 micrograms of ethinylestradiol can significantly alter carbohydrate metabolism in older women.

Six-month carbohydrate metabolism studies in women using oral contraceptives containing gestodene and ethinyl estradiol

Twenty-five women had their carbohydrate metabolism prospectively evaluated during the six months that they used a gestodene and ethinyl estradiol monophasic oral contraceptive. Serum glucose and insulin levels were measured during a 75-gram three-hour oral glucose tolerance test. At the six-month test, the three-hour glucose and the fasting and three-hour insulin values were significantly elevated. The literature on carbohydrate metabolism during gestodene oral contraceptive use is also reviewed.

Carbohydrate metabolism after three months of using a gestodene-containing monophasic oral contraceptive

Carbohydrate metabolism was prospectively evaluated in twenty-one normal women prior to and during their use for three months of a monophasic oral contraceptive containing the progestin gestodene plus ethinyl estradiol. The women had a three-hour oral glucose tolerance test using a 75 gram glucose load, measuring serum glucose and insulin levels. The results demonstrate no significant changes in either of the carbohydrate metabolic indices between the two tests. These data support the safety of this new progestin-containing contraceptive.

Carbohydrate metabolic studies in women using a levonorgestrel/ethinyl estradiol containing triphasic oral contraceptive for eighteen months

Carbohydrate metabolism was evaluated in 17 women before and after 18 months of triphasic oral contraceptive use. The triphasic oral contraceptive contained levonorgestrel and ethinyl estradiol. An oral glucose tolerance test was utilized and both plasma glucose and insulin levels were measured. There were no significant changes in the glucose levels. The fasting insulin level was raised at the 18-month test, whereas the other insulin values were similar. These results demonstrate that the new triphasic oral contraceptive preparations produce minimal carbohydrate metabolic changes.

Two-year carbohydrate metabolism studies in women using a norethindrone or levonorgestrel triphasic oral contraceptive

Carbohydrate metabolism was prospectively studied in 28 women using triphasic oral contraceptives (TOC) for two years. They were tested using a 100-gram oral glucose tolerance test with measurements of plasma glucose and insulin levels during the three-hour test. The women were randomly assigned to either a norethindrone-containing TOC or a levonorgestrel-containing TOC. Both types of drugs contained the estrogen ethinyl estradiol. No significant changes were noted in the norethindrone TOC group. The levonorgestrel TOC two-year test had a significant elevation of the 0.5- and 2-hour plasma glucose values and the fasting insulin value. These data show that the two triphasic oral contraceptive preparations affect carbohydrate metabolism differently.

Plasma glucose and insulin levels during the menstrual cycles of normal women and premenstrual syndrome patients

Three-hour oral glucose tolerance tests were performed on days 5 and 25 of ovulatory menstrual cycles in 26 women. The women were divided into normal (n = 9) and premenstrual syndrome (PMS) (n = 17) categories. Ovulation was confirmed by basal body temperature records and plasma progesterone levels. There were no statistically significant changes in the plasma glucose or insulin levels between the two tests in either group. Except for a higher two-hour plasma insulin concentration on the day 5 test in normal women, no statistically significant carbohydrate differences were noted between the groups. The data suggest that alterations in carbohydrate metabolism are not important in PMS.

Selective inhibition of protein disulfide isomerase by estrogens

Protein disulfide isomerase (PDI) is a multifunctional microsomal enzyme that participates in the formation of protein disulfide bonds. PDI catalyzes the reduction of protein disulfide bonds in the presence of excess reduced glutathione and has been implicated in the reductive degradation of insulin; E. coli thioredoxin is homologous to two regions in PDI and can also degrade insulin. PDI activity, measured by 125I-insulin degradation or reactivation of randomly oxidized RNase in the presence of reduced glutathione, is non-competitively inhibited by estrogens; half-maximal inhibition was observed at approximately 100 nM estrogen. Other steroid hormones at 1 microM had little or no effect. PDI segment 120-163 (which corresponds to exon 3 of the PDI gene) and 182-230 have significant similarity with estrogen receptor segments 350-392 and 304-349, respectively, located in the estrogen binding domain but not with the steroid domains of the progesterone and glucocorticoid receptors or with thioredoxin, which is insensitive to estrogens. We propose the hypothesis that enzymes can acquire sensitivity to a hormone via exon shuffling to the enzyme gene from the DNA region coding for the hormone binding domain of the hormone's receptor.

Glucose and insulin levels after six months of treatment with a triphasic oral contraceptive containing ethinyl estradiol and norethindrone

A prospective study of carbohydrate metabolism was done on 33 women who used a triphasic oral contraceptive (OC) containing ethinyl estradiol and norethindrone for six months. A three-hour oral glucose tolerance test was administered before and after the OC usage, and both the blood glucose and insulin levels were determined. A significant decrease in the fasting glucose level was found with treatment. All other glucose values and insulin levels were unchanged.

Insulin and insulin-like growth factor I in brain tumors: binding and in vitro effects

We have measured insulin and insulin-like growth factor I (IGF-I) binding in human gliomas, meningiomas, and normal brain and studied the effect of insulin on the morphology, proliferation, and differentiation of central nervous system tumor and normal fetal cells in culture. Specific 125I-insulin and 125I-IGF-I binding was demonstrated by competition-inhibition binding assays. Insulin binding was measured in plasma membrane preparations from 9 freshly isolated human meningiomas, 4 glioblastomas multiforme (GBMs), a low-grade glioma, a normal adult brain, and a fetal brain. IGF-I binding was measured in similar preparations from 5 meningiomas, 4 GBMs, a low-grade glioma, and a normal adult brain. Incubations were carried out at 4 degrees C for 18 to 20 hours. Meningiomas showed higher specific insulin binding per 0.25 mg of protein than GBMs (19% versus 3%, P less than 0.005), and this difference was not related to small differences observed in insulin degradation. By contrast, IGF-I binding was significantly higher in gliomas than in meningiomas (27% versus 12%, P less than 0.05). Also, IGF-I binding was significantly higher than insulin binding in GBMs (27% versus 3%, P less than 0.03); binding of both IGF and insulin was high in meningiomas. In normal adult brain IGF-I and insulin binding was 7 to 10%. The ability of insulin to support and enhance the growth of central nervous system tumor cells in culture was investigated. Cell cultures were derived from a freshly isolated glioblastoma, a low-grade glioma, and 3 meningiomas.(ABSTRACT TRUNCATED AT 250 WORDS)

Carbohydrate studies in women using a norethindrone triphasic oral contraceptive for eighteen months

Twenty women were tested before and after eighteen months of use of triphasic oral contraceptive (TOC) containing norethindrone and ethinyl estradiol (7-7-7). The evaluation was with an oral glucose tolerance test and plasma glucose and insulin levels were measured. The results showed a lower fasting glucose and elevated one-hour insulin values after TOC use. These results suggest improved safety with these contraceptives.

The effects of two triphasic oral contraceptives on carbohydrate metabolism in women during 1 year of use

Sixty-one women were randomly assigned to use one of two different triphasic oral contraceptives (OCs), for one year's time (Ortho Novum 777, Ortho Pharmaceutical Corp., Raritan, NJ, and Triphasil, Wyeth Laboratories, Philadelphia, PA), containing the progestins norethindrone and levonorgestrel, respectively. The carbohydrate metabolism was evaluated using the oral glucose tolerance test before OC use and at the end of the 12th month. Both plasma glucose and insulin levels were measured. The fasting glucose value in the norethindrone-containing OC group (777) was significantly lower at the 1-year testing. All other values were unchanged. These data demonstrate that the triphasic oral contraceptive preparations currently in use have minimal effects on carbohydrate metabolism.

Human uterine leiomyoma cells: binding and growth responses to epidermal growth factor, platelet-derived growth factor, and insulin

The specific binding of epidermal growth factor (EGF), platelet-derived growth factor (PDGF) and insulin were measured in matching cultures of human leiomyoma and myometrial cells, along with the effects of these proteins on DNA and protein syntheses. Scatchard analyses of the binding data revealed that the EGF receptor sites/cell were significantly lower in leiomyoma than myometrial cultures. Two types of PDGF binding were observed when porcine PDGF was used, and one type was seen with human PDGF. By contrast to EGF, more PDGF receptor sites/cell were found in leiomyoma than myometrium but the receptor affinity was higher in the latter. Insulin binding was similar among the myometrial and leiomyoma cells. Protein synthesis was stimulated 3-fold by EGF, PDGF, or insulin in both cell types. DNA synthesis, was higher in myometrial than leiomyoma cells in the basal state and was stimulated by EGF, insulin, or PDGF. A synergistic stimulation (p less than 0.02) of DNA synthesis was observed in both myometrial and leiomyoma cells when EGF was added with insulin. The addition of PDGF with insulin caused only additive stimulation of DNA synthesis. However, the addition of EGF with PDGF caused a synergistic decrease (p less than 0.05) in DNA synthesis by myometrial but no leiomyoma cells. Cultures of human vascular smooth muscle cells obtained from umbilical veins gave results similar to those from myometrium. These findings single out the EGF receptor and EGF, or perhaps an EGF-like growth factor, and to a lesser degree PDGF, as potential regulators of uterine leiomyomata.

Prospective study of carbohydrate metabolism in women using a triphasic oral contraceptive containing norethindrone and ethinyl estradiol for 3 months

Thirty-five women with normal carbohydrate metabolism were administered a 3-hour oral glucose tolerance test before and after 3 months' use of a triphasic oral contraceptive that contained ethinyl estradiol and norethindrone. The results show no significant change in either the plasma glucose or the insulin values. This is the first published study with regard to this type of triphasic oral contraceptive, and the study supports claims of the preparation's improved safety.

Plasma glucose and insulin levels in women using a levonorgestrel-containing triphasic oral contraceptive for three months

Plasma glucose and insulin levels were measured for three hours after an oral glucose challenge in twenty-nine women before and after using a triphasic oral contraceptive containing ethinyl estradiol and levonorgestrel for three months. There were significant elevations in the glucose levels during the three-month tolerance test, while the insulin levels were unchanged. These data suggest that this OC can alter carbohydrate metabolism and that long-term studies are needed to assess the extent of this metabolic change.

Cervicovaginal peroxidases: markers of the fertile period

The specific activity of guaiacol peroxidase was measured daily in human cervical mucus, vaginal fluids, and saliva during 45 cycles in 31 women. Also determined were basal body temperatures and serum hormones (luteinizing hormone [LH], estradiol, progesterone). The guaiacol peroxidase was extracted with 0.5 M CaCl2 and thus may be a different peroxidase from that obtained by noncalcium extraction procedures. The guaiacol peroxidase specific activity did not vary in the saliva during the cycle but fell sharply in the cervical mucus and vaginal fluid four to five days before the ovulation time, estimated by the LH peak, and rose again one to two days after ovulation. Anovulatory cycles did not show the midcycle drop in guaiacol peroxidase. Growth curve analysis gave excellent fitting of the guaiacol peroxidase data to a polynominal model. These data suggest that cervicovaginal guaiacol peroxidase may be clinically useful in detecting the fertile period for population control and for infertility treatment.

In vitro binding of insulin and epidermal growth factor to human endometrium and endocervix

The distribution of receptors for insulin and epidermal growth factor along the longitudinal axis of the uterine cavity was studied in 28 uteri obtained from women of reproductive age undergoing hysterectomy for benign conditions. Insulin binding to crude plasma membranes was higher (p less than 0.05) in the secretory than in the proliferative phase of the menstrual cycle in all uterine segments (fundus to cervix). Epidermal growth factor binding did not change during the menstrual cycle but the number of epidermal growth factor binding sites was higher in the cervix than in the fundus (p less than 0.05). Scatchard plots of binding data, obtained with crude plasma membranes from pooled uteri, were curvilinear; the high-affinity sites had dissociation constants of 1 to 4 nmol/L and receptor concentrations of 100 to 300 fmol/mg of protein, for both iodine 125-labeled insulin and 125I-labeled epidermal growth factor. In plasma membranes, obtained from another 15 uteri, mouse nerve growth factor (3.3 micrograms/ml) decreased the binding of insulin by an average of 17% (p less than 0.005); in the decidua of a pregnant uterus at 12 weeks Scatchard analysis showed that nerve growth factor decreased the affinity but not the number of insulin-binding sites. Nerve growth factor had no effect on epidermal growth factor binding. Human prolactin (2 micrograms/ml) also decreased insulin binding by an average of 18% (n = 5, p less than 0.025) but had no effect on epidermal growth factor binding. These "baseline" data will be useful in further studies of the possible interactions between (1) receptors for various peptide growth factors and (2) sex steroid hormones, in normal and neoplastic endometrium and cervix.

Cervicovaginal peroxidases: sex hormone control and potential clinical uses

Thirty-one normal women were studied daily in 41 cycles. Venous blood samples were taken for measurements of luteinizing hormone (LH), estradiol (E2), and progesterone (P), and vaginal examinations were done to obtain cervical mucus and vaginal fluid. The specific activity of guaiacol peroxidase (GP), extracted from cervicovaginal secretions with 0.5 M CaCl2, was determined in the vaginal samples. In the follicular phase, from day -7 to day 0 (the LH +1 day, when ovulation presumably occurred), there was a strong negative correlation between GP and the rising E2 (r = -0.94). On days 1 to 10 after ovulation, there was a strong positive correlation between GP and P (r = 0.84). In nine ovulatory cycles in which P levels did not exceed 8 ng/ml on any day, indicating possible luteal phase inadequacy, there were significantly lower GP levels than in another 32 ovulatory cycles with higher P (P = 0.04). These results suggest that (1) at midcycle, E2 seems to "down-regulate" the GP specific activity; and (2) in the luteal phase, serum P levels parallel those of GP activity, even in the presence of high luteal E2. GP activity profiles during the menstrual cycle can be used to define the fertile period, may prove useful in diagnosing pregnancy, and may be a simple, convenient test for an inadequate corpus luteum.

Insulin binding to human ovaries

Human ovarian tissue samples were obtained at the time of laparotomy, and plasma membrane fractions were prepared and used in receptor assays. Incubations of the membrane fraction were performed with [125I]insulin (porcine), and Scatchard analysis of binding showed biphasic curves. The high affinity sites had an average concentration of 57.4 +/- 7.9 (+/- SEM) fmol/mg protein and a dissociation constant of 3.5 +/- 0.9 nM (n = 9). Neither affinity nor number of binding sites changed significantly during the menstrual cycle. We conclude that there is high affinity binding of [125I]insulin to human ovarian plasma membranes.

The effect of prolactin and relaxin on insulin binding by adipocytes from pregnant women

The effects of prolactin and relaxin on insulin binding by isolated human adipocytes from women at term gestation were studied in vitro. It was found that prolactin decreases, and relaxin increases, insulin binding to the adipocytes. Both changes appear to be due to alterations in the affinity of the insulin receptors. These effects seem to be mediated through specific prolactin and relaxin receptors of the adipocyte and require the presence of an intact cellular cytoskeleton. This suggests that one hormone, for example, prolactin, can interact with its own specific receptor and thereby after the affinity of a heterologous receptor for its hormone (insulin). Heterologous hormone-receptor complex interactions ("cross-talk") may be widespread and could represent a fundamental mechanism in the functioning of the endocrine system.

The effect of sex steroids on insulin binding by target tissues in the rat

The effect of estradiol, progesterone and norgestrel on serum insulin and glucose levels and on insulin binding to adipocytes, hepatocytes and diaphragm muscle cell membranes has been evaluated in castrated male rats. Estradiol administration (5 micrograms/day X 6) significantly increased basal plasma insulin levels and the amount of insulin bound to fat and liver cells as well as muscle cell membranes. Progesterone treatment (5 mg/day X 6) caused a slight increase of basal insulin levels and a decrease of insulin binding to fat cells. Norgestrel treatment (5 mg/day X 6) decreased both insulin levels and the amount of insulin bound to adipocytes; a much lower dose of norgestrel, 6 micrograms/day X 7, also caused a decline in adipocyte insulin binding due to an apparent increase in the dissociation constant of the high affinity binding sites. These studies demonstrate that ovarian sex steroids have a significant effect on insulin binding to target cells. This animal model would assist in determining the mechanisms involved in changes of carbohydrate metabolism which occur during the menstrual cycle, pregnancy, the menopausal state and with the use of oral contraceptives.

Distribution of guaiacol peroxidase in human endometrium and endocervical epithelium during the menstrual cycle

Guaiacol peroxidase (G-Px) was measured in extracts from five sections along the length of human uterus on different days of the menstrual cycle or after menopause. The lower uterine-endocervical region had a significantly higher G-Px content (expressed as enzyme units per g wet tissue) than the other sections, although in postmenopausal patients the G-Px activity was uniformly low in all sections of the uterine cavity. We observed no significant changes in G-Px levels during the menstrual cycle, except, possibly, a decrease around ovulation, which precluded a positive correlation between plasma estrogen levels and uterine G-Px content; such estrogen dependence of G-Px has been previously shown in the rat. In vitro, G-Px was inhibited by estriol and 17 beta-estradiol, marginally inhibited by estrone, and most notably inhibited by the catecholestrogens tested (2-hydroxy-17 beta-estradiol, 2-hydroxy-estriol, and 2-hydroxy-estrone), which were equipotent inhibitors; LH and FSH, progesterone, or cortisol had no effect on G-Px activity. We hypothesize that catecholestrogens are natural substrates and regulations of G-Px activity in the human uterus.

Insulin receptors in circulating erythrocytes and monocytes from women on oral contraceptives or pregnant women near term

Altered carbohydrate metabolism occurs in women during pregnancy and in those using oral contraceptives (OC). Insulin binding to circulating erythrocytes and monocytes was studied in 77 nonobese, healthy women volunteers; they were divided into 4 groups: 1) late pregnant (n = 19),2) OC users taking 50 microgram estrogen daily (OC-50; n = 19),3) OC users taking 35 microgram estrogen daily (OC-35; n = 18), and 4) a control group (n = 21). All nonpregnant volunteers were in the luteal phase (days 18-21) of the menstrual cycle. Oral glucose tolerance tests were normal in all groups. Fasting plasma insulin was higher (P < 0.001) in the pregnant group, and plasma insulin responses to the oral glucose tolerance test were higher (P < 0.05) in the pregnant, OC-35, and OC-50 groups compared to that in the control group. The percentage of specific binding of [125I]insulin to 1.2 x 10(7) monocytes/ml (and 4.4 x 10(9) erythrocytes/ml) was similar in all groups (mean +/- SE): pregnant, 6.85 +/- 0.48% (6.85 +/- 0.59%); OC-35, (6.85 +/- 0.40%); OC-50, 6.95 +/- 0.55% (6.73 +/- 0.59%); and control 6.66 +/- 0.64% (7.17 +/- 0.44%). No correlation was found between insulin binding to erythrocytes and monocytes. Average affinity profiles and binding sites per cell (70/erythrocyte and 50,000/monocyte, respesctively) were similar in all groups. Since insulin binding to monocytes in decreased during the secretory phase of the menstrual cycle, one could extrapolate from our data that pregnant women will have lower insulin binding compared to nonpregnant women in the proliferative phase of the cycle; such a report has appeared recently (Beck-Nielsen et al., J Clin Endocrinol Metab 49: 810, 1979). Differences in plasma levels of estrogen and progesterone between the secretory and proliferative phases of the cycle are much smaller than between the nonpregnant state and late pregnancy. Therefore, it remains to be seen whether these steroid hormones would cause, by the same mechanism, a decrease in insulin binding (and insulin resistance) during late pregnancy and in the secretory phase of the cycle.

Endometrial estrogen and progesterone receptors in a uterus didelphys

A 23-year-old woman with a uterus didelphys and a totally occluded left tube had a hysterectomy one year after having a child. Endometrial estrogen and progesterone receptors, both cytoplasmic and nuclear, were determined in five longitudinal sections of each horn. The amount and distribution of these receptors were normal, but the receptor content of the right horn was higher than that of the left.

Carcinogen activation by human uterine enzymes

Three topics are briefly reviewed relating to carcinogenesis of estrogen responsive tissues: (a) enzymology of benzo(a)pyrene activation by human tissues, (b) microsomal activation of estrogens to estrogen arene oxides and (c) estrogen and progesterone receptor studies in endometrial carcinoma. The following working hypothesis is stated on the etiology of gynecologic tumors: "Environmental chemicals, such as cigarette smoke, polycyclic and polyhalogenated hydrocarbons, etc., induce special forms of cytochrome P-450 monooxygenase and related enzyme systems which can activate endogenous or prescribed estrogens and non-steroid antiestrogens to act as initiators and/or promoters of neoplasia in estrogen-dependent organs." The role of estrogen receptors is perceived as a homing device or cellular "Trojan Horse" for these activated estrogens.

Distribution of cytoplasmic estrogen and progesterone receptors in human endometrium

Unoccupied estrogen receptors and progesterone receptors were measured in the cytoplasm of five sections along the length of endometrium obtained from noncancerous, premenopausal hysterectomy specimens. The concentrations of the two receptors were measured with tritiated estradiol or R5020 (a synthetic progestin), the latter two having been purified by high-pressure liquid chromatography, and were found to be highest in the fundus and lowest in the cervix. Progesterone receptor levels, ranging from 50 to 3,500 fmoles of R5020 bound per milligram of protein, were generally much higher in each section of the endometrium than estrogen receptor levels, which ranged from 0 to 500 fmoles of estradiol bound per milligram of protein. Near ovulation it seemed that the distribution profiles of both receptors became very steep, with more than a tenfold difference in the receptor levels being found between the fundus and the cervix. Receptor levels measured in endometrial samples obtained by curettage or aspiration should be interpreted with caution.