Fundal Myometrium Research Articles

Characterization of topology-, gestation- and labor-related changes of a cassette of myometrial contraction-associated protein mRNA in the pregnant baboon myometrium.

Our objective was to examine the topology-, gestation- and labor-related changes of estrogen receptor (ER)alpha, progesterone receptor (PR), oxytocin receptor (OTR) and thrombospondin-1 (TSP1) mRNA in pregnant baboon myometrium. ER alpha, PR, OTR and TSP1 mRNAs extracted from the lower uterine segment and fundal myometrium of pregnant baboons not in labor between 121 and 180 days of gestational age (n=9) and in established spontaneous labor between 164 and 193 days of gestational age (n=5) were analyzed by Northern blot. There were no topology-, gestation- or labor-related changes of ER alpha and PR mRNA in or between the lower uterine segment or/and the fundus. OTR mRNA was the same in the lower uterine segment and the fundus from baboons not in labor and non-labor fundal, but not lower uterine segment, myometrial OTR mRNA increased with gestation (R(2)=0.81, P<0.05). Fundal OTR mRNA rose significantly compared with the lower uterine segment during spontaneous labor. TSP1 mRNA increased significantly in both the fundus and lower uterine segment during labor. TSP1 mRNA in the lower uterine segment during spontaneous labor was higher than in the fundus during spontaneous labor. In conclusion, fundal and lower uterine segment ER alpha and PR mRNA remained unchanged in late gestation and spontaneous labor. The increased OTR mRNA may serve as a mechanism to increase uterine sensitivity to OT during late gestation. The higher fundal OTR mRNA compared with the lower uterine segment provides polarity which assists fetal expulsion by uterine contractions during labor. The significance of increased TSP1 mRNA during labor may relate to homeostasis and merits further study.

Frameless versus classical intrauterine device for contraception.

The frameless intrauterine device (IUD) dispenses with the frame in the classical IUD and holds the device in the uterus by anchoring one end of a nylon thread in the fundal myometrium, to which copper sleeves are attached. The introducer for the frameless device was modified following reports of early expulsions of the device. This review examines the hypothesis that the frameless device reduces risk of expulsion and pregnancy, and the problems of bleeding and pain necessitating early removal. We searched the Cochrane Controlled Trial Register (Cochrane Library Issue 1, 2001), MEDLINE, EMBASE and Popline to Dec 2000, and reference list of articles. We selected for the review randomised trials that compared the frameless device to a classical framed device for contraception. Both authors extracted data independently. We contacted study author for additional data. We calculated rate ratios and rate differences for cumulative rates for each outcome at yearly intervals. We used the general variance-based method to combine trials, and tested the results for heterogeneity. Three trials were included in the review involving over 5,800 women randomised to either a frameless device or TCu380A, with data up to eight years for the largest, and with a total experience of 23,000 women-years. All three trials excluded nulliparous women. The two earlier trials used a prototype introducer and there was a higher expulsion rate at one year (relative risk 2.48, 95% confidence intervals 1.89 to 3.26). However, between two and six years in the large WHO trial the risk of pregnancy was lower with the frameless device (relative risk 0.53, 95% confidence intervals 0.32 to 0.91). In a recent trial using GyneFix with a new introducer early expulsions and pregnancies were not statistically different from the control device; by the third year the expulsion rate with the frameless device was lower (relative risk 0.41, 95% confidence intervals 0.19 to 0.87) with no difference in pregnancy rate. Removals rates for excessive bleeding and/or pain were no different between the devices (relative risks 0.92, 95% confidence intervals 0.74 to 1.14, at one year and 1.13, 0.93 to 1.37, at six years). There was a tendency towards fewer removals for pain in early years but no difference at six years (relative risk 1.13, 95% confidence intervals 0.93 to 1.37). There are insufficient data to show that problems of early expulsions have been overcome with the new introducer used in GyneFix. Apart from that, the frameless device performs similarly to TCu380A, and appears to have a lower pregnancy rate in later years, although the absolute difference is small.

Expulsions following 1000 GyneFix insertions

ContextThe GyneFix intra-uterine device has been used in our family planning service since 1997. One of the perceived advantages is its low expulsion rate, as reported by clinical trials.ObjectiveTo calculate...

Prostaglandin dehydrogenase mRNA in baboon intrauterine tissues in late gestation and spontaneous labor.

The present study was designed to characterize prostaglandin dehydrogenase (PGDH) mRNA expression in critical intrauterine tissues of pregnant baboons in late gestation and at spontaneous labor. In addition, we determined regulatory effects of betamethasone in vivo on chorionic and placental PGDH mRNA expression. PGDH mRNA was present in chorion, decidua, lower uterine segment, fundal myometrium, and cervix in late gestation but undetectable in amnion. PGDH mRNA significantly decreased in decidua and cervix during late gestation and in chorion and fundus during spontaneous labor. PGDH mRNA in lower uterine segment, decidua, cervix, and placenta was unchanged during spontaneous labor from late gestation levels. Betamethasone had no effect on chorionic and placental PGDH mRNA expression. In summary, our data suggest that PGDH mRNA expression is tightly controlled in gestation- and tissue-specific manners. Decreased chorionic and fundal PGDH abundance during labor and decreased decidua and cervical PGDH mRNA in late gestation allow local uterine prostaglandin accumulation and assist prostaglandin transfer to myometrium. Local differences in PGDH function may regulate tissue- and region-specific requirements for prostaglandins to promote and complete labor.

Human Uterine Myocytes Retain Their Energy Charge with No Gross Alterations in Morphology for at Least 8 Days when Cultured under Anaerobic Conditions

Objective: To investigate the ability of human uterine myocytes to grow under anaerobic conditions for a prolonged time period. Methods: Cells were isolated from fundal myometrium and cultured until subconfluency. The cell type was confirmed by immunostaining for the smooth muscle cell-specific cytoskeletal proteins α-actin and desmin. Some cells were further cultured under aerobic conditions and others under anaerobic conditions. Cells were harvested after 0, 4 and 8 days in culture and analyzed for their content of adenylates. Results: Immunostaining revealed that all three preparations contained almost only smooth muscle cells. Energy charge of the myocytes was 0.88 on average at the beginning of the culture experiment. A moderate decrease was noted on day 4 for myocytes grown under both aerobic and anaerobic conditions and no further decrease was noted between days 4 and 8. Morphologically the cells retained their normal appearance and they seemed healthy for at least 8 days in culture under both aerobic and anaerobic conditions. Conclusions: The results of this study suggest that human myometrial cells can survive for an extended period of time under in vitro conditions regardless of oxygen availability for energy metabolism. This means that anaerobic energy metabolism is enough to sustain vital processes during that period of time.

Late uterine perforation with an anchored IUD, the Gynefix®: a case report

A case of uterine perforation which occurred two months after the insertion of a Gynefix®, a frameless filiform copper intrauterine device fixed into the fundal myometrium is described. Laparoscopic removal of the device had to be performed. The incidence of this complication is unknown. The appropriateness or need of assessing echographically the myometrial thickness before the insertion and of controlling its correct position after the insertion remains uncertain.

Slow train gathers speed

The otherwise slow pace of contraceptive research developments has recently quickened, with new products developed, more on the way, and encouraging new data emerging about existing methods. While the 1995 UK pill scare called attention to a differential in the risk of venous thromboembolism (VTE) between pills containing levonorgestrel or norethisterone and those containing desogestrel or gestodene, there is only an extremely small level of excess mortality attributable to third-generation progestogens, less than 2 per million women per year. Tentative evidence suggests that pills with less anti-estrogenic progestogens are neutral with regard to coronary artery disease. The pill remains extremely safe for healthy young women, although additional research with larger numbers of participants is warranted. Salient research findings are that the combined oral contraceptive pill may protect against colon cancer, the pill appears to offer no protection against bone fractures, new products contain less estrogen and have a shortened pill-free interval, a WHO paper showed no significant association between cardiovascular disease and the use of oral or injectable progestogens, a UK study showed no correlation between bone density and plasma estrogen concentrations among long-term users of depot medroxyprogesterone acetate, and a WHO controlled trial found a progestogen-only method of emergency contraception to be considerably more effective in preventing expected pregnancies than the Yuzpe regimen. The T 380 copper IUD provides very high protection against intrauterine and extrauterine pregnancies for 10 years and is now available in an improved inserting mechanism, the Mirena levonorgestrel-releasing IUD system is now licensed for 5 years, and the GyneFIX IUD implant is a frameless device fixed during insertion to the fundal myometrium.

Sonographic evidence for the involvement of the utero-ovarian counter-current system in the ovarian control of directed uterine sperm transport.

Sperm transport from the cervix into the tube is an important uterine function within the process of reproduction. This function is exerted by uterine peristalsis and is controlled by the dominant ovarian structure via a cascade of endocrine events. The uterine peristaltic activity involves only the stratum subvasculare of the myometrium, which exhibits a predominantly circular arrangement of muscular fibres that separate at the fundal level into the fibres of the cornua and continue into the circular muscles of the respective tubes. Since spermatozoa are transported preferentially into the tube ipsilateral to the dominant follicle, this asymmetric uterine function may be controlled by the ovary via direct effects utilizing the utero-ovarian counter-current system, in addition to the systemic circulation. To test this possibility the sonographic characteristics of the uterine vascular bed were studied during different phases of the menstrual cycle. Vaginal sonography with the measurement of Doppler flow characteristics of both uterine arteries and of the arterial anastomoses of the uterine and ovarian arteries (junctional vessels) in the cornual region of both sides of the uterus during the menstrual phase of regular-cycling women demonstrated significant lower resistance indices of the junctional vessels ipsilateral to the side of the dominant ovarian structure as compared with the corresponding arteries contralaterally. By the use of the perfusion mode technique, it could be observed that vascular perfusion of the fundal myometrium was significantly increased ipsilateral to the dominant follicle during the late follicular phase of the cycle. These results show that the endocrine control of the dominant ovarian structure over uterine function is not only exerted via the systemic circulation but also directly, most probably utilizing the utero-ovarian counter-current system.

Treatment of placental site trophoblastic tumor with hysterotomy and uterine reconstruction

Placental site trophoblastic tumor is an unusual variant of gestational trophoblastic neoplasia that is usually confined to the uterus, although 10% of patients have metastases. Because this tumor occurs in women of reproductive age, preservation of fertility may be relevant. Therefore, local excision of placental site trophoblastic tumor by hysterotomy may have a place in management. A 25-year-old woman, gravida 1, para 1, presented with irregular bleeding. Uterine curettage revealed intermediate trophoblasts that on immunostaining were positive for hCG and human placental lactogen, consistent with placental site trophoblastic tumor. Endovaginal ultrasonography and magnetic resonance imaging demonstrated tumor localized to the anterior fundal myometrium. The patient underwent local excision of the tumor by hysterotomy followed by uterine reconstruction. Pathologic examination confirmed that the surgical margins were free of tumor. The patient has had no recurrence. Two subsequent pregnancies resulted in two spontaneous abortions. A third pregnancy was carried to term. The patient was delivered by cesarean because of the hysterotomy. The hysterotomy scar was intact at cesarean. Hysterectomy has been recommended by most authors for treatment for placental site trophoblastic tumor. In some patients with localized placental site trophoblastic tumor who desire preservation of fertility, more conservative surgical therapy may be considered.

Myometrial arginase activity increases with advancing pregnancy in the guinea pig

OBJECTIVES: Arginase has been suggested to play an important role in cellular growth and development, particularly important to the fetus, by supplying L-ornithine for the synthesis of polyamines. The purpose of this investigation was to determine whether pregnancy alters myometrial arginase activity and whether estradiol was responsible for the change. STUDY DESIGN: Myometrium and kidney were obtained from nonpregnant and pregnant guinea pigs of known gestational age. Arginase activity was measured under physiologic conditions by the conversion carbon 14 - labeled guanidino-L-arginine to carbon 14 - labeled urea. The concentrations of the enzyme's substrate, L-arginine, and its principal metabolite, L-ornithine, were measured in myometrium from near-term pregnant animals by use of an amino acid analyzer. Finally, a group of random cycle guinea pigs received 500 μg/kg estradiol for 5 days before the myometrium was removed. RESULTS: Myometrial arginase activity in pregnant animals was more than double that of myometrium from nonpregnant animals by the time the first measurement was made at 0.14 gestation. It continued to rise, peaking at values >25-fold higher than the nonpregnant activity by 0.90 gestation. Arginase activity in the myometrium underlying the placental implantation site was >25 fold higher ( p < 0.05) than myometrium from nonpregnant animals when first studied at 0.63 gestation and 10-fold higher than the contralateral fundal myometrium at the same time of gestation. Myometrial arginase activity in the sterile horn of six pregnant animals was half that of the horn containing one or more pups, but still five times higher than that of nonpregnant animals. Renal arginase activity also rose with advancing pregnancy, but the magnitude of the increase (up to 2-fold) was much smaller than that observed in either the fundal or placental implantation site myometrium. Estradiol had no significant effect on myometrial arginase activity. CONCLUSIONS: These studies demonstrate that pregnancy increases myometrial arginase activity and that the presence of placenta or fetus is necessary for the maximal effect. (A M J O BSTET G YNECOL 1996;174:779-82.)