Nitric oxide in the endometrium. (1/815)

Nitric oxide (NO) is an important mediator of paracrine interactions, especially within the vascular system. It is a powerful inhibitor of platelet aggregation and a potent vasodilator. NO is also a neurotransmitter and it plays a role in cell-mediated cytotoxicity. NO-generating enzymes (nitric oxide synthases, NOS) have been described in the endometrium of a number of species, suggesting that NO might be involved in endometrial function. In human endometrium, endothelial NOS and inducible NOS have been localized to glandular epithelium in the non-pregnant uterus. Weak inducible NOS immunoreactivity has been observed in decidualized stromal cells. NO might participate in the initiation and control of menstrual bleeding. Furthermore, it may play a part in the inhibition of platelet aggregation within the endometrium, where menstrual haemostasis is thought to occur primarily by vasoconstriction rather than clot organization. Endometrially derived NO could also suppress myometrial contractility. Recent attention has focused on the part that NO might play in maintaining myometrial quiescence during pregnancy. NO also appears to relax the non-pregnant myometrium, an action which could be exploited for the medical treatment of primary dysmenorrhoea.  (+info)

Mechanism of action and clinical effects of antiprogestins on the non-pregnant uterus. (2/815)

Considerable progress has been made in elucidating the mechanism of action of antiprogestins. The biological response to a progesterone antagonist depends on many factors. The usual effect is that of an antagonist, but progesterone agnostic or even antioestrogenic or oestrogenic effects have also been observed. The present review focuses on the clinical applications of antiprogestins in the non-pregnant uterus. Whereas high doses of antiprogestins block ovulation, low doses impair endometrial development without affecting ovulation, hormonal levels or bleeding patterns Indeed, the endometrium is the tissue which is the most sensitive to antiprogestins. The effect of antiprogestins is to produce a delay in endometrial maturation and to postpone the appearance of the implantation window. This concept of 'endometrial contraception' requires further testing in humans, although the principle has been proven in monkeys. In contrast to the low doses of mifepristone which delay endometrial maturation, a minimum dose of 50 mg is required to produce endometrial bleeding. Late luteal phase antiprogestin administration does not disturb ovulation, hormonal levels or bleeding patterns. This has clinical application, and mifepristone has been used together with prostaglandins in women with delayed menses to successfully prevent implantation. Mifepristone has also been shown to be an effective post-coital agent. However, when used on a regular basis once monthly at the end of the cycle as a potential contraceptive, the results are disappointing. Because of their antiproliferative and anti-oestrogenic effects on the endometrium, antiprogestins are also used in the treatment of oestrogen-dependent conditions such as endometriosis and fibromyomas. In humans, chronic administration of high doses of antiprogestins has on rare occasions been associated with endometrial hyperplasia, presumably a consequence of unopposed oestrogen activity. This does not occur with low doses (1 mg daily for 5 months).  (+info)

Individual growth patterns in the first trimester: evidence for difference in embryonic and fetal growth rates. (3/815)

OBJECTIVE: To evaluate individual fetal growth during the first trimester in pregnancies resulting from spontaneous and in vitro fertilization (IVF). METHODS: The growth of 11 fetuses conceived by spontaneous fertilization (known dates of ovulation) in nine patients and 15 fetuses conceived by IVF in 12 patients were evaluated at weekly intervals from 6 weeks, menstrual age, to 14 weeks. Fetal length was determined at each examination. Measures of fetal length included the crown-rump length (CRL), maximum straight line length (MSLL) and maximum axial length (MAL). Comparisons of CRL and MSLL to MAL were carried out. The MSLL was used as the measure of length except when the MAL was available. Linear and quadratic functions were fitted to the complete data sets of individual fetuses in the two groups. Individual data sets from ten fetuses in each group were then divided into early and late growth phases, and linear functions were fitted to each data subset. Start points and pivotal points for each fetus were estimated from the coefficients of these two functions. Growth in these two groups of fetuses was compared, on the basis of slope values. RESULTS: Evaluation of length measures indicated that, before 8 weeks, only MSLL could be measured. After 8 weeks, all three measures could be obtained, with the MAL being the largest. Both the linear and quadratic models performed well with individual data sets (mean R2(+/- SD): linear 98.1 (1.0)%; quadratic 99.4 (0.4)%), with no differences found between spontaneous and IVF groups (maximum possible differences in mean slopes (95% probability): 5-8%). Similar findings were obtained for the early and late growth phase data subsets. Slope values in the early and late growth phases showed low variability (CV: early 13.5%; late 11.6%), but were significantly different (early 0.72 (+/- 0.10 SD) cm/week; late 1.21 (+/- 0.14 SD) cm/week). The mean start point was 5.9 (+/- 0.3 SD) weeks' menstrual age, while the mean pivotal point was 9.2 (+/- 0.7 SD) weeks, menstrual age. CONCLUSIONS: First-trimester growth studies in individual fetuses indicate that there is a change in length growth rate between 9 and 10 weeks, menstrual age. This is consistent with a shift in development from organogenesis to growth. These results can be used for more accurate assessment of first-trimester growth and may aid in the detection of fetal problems that manifest themselves as growth abnormalities.  (+info)

Clinical interpretation of ultrasound biometry for dating and for assessment of fetal growth using a wheel and chart: is it sufficiently accurate? (4/815)

OBJECTIVES: To investigate how accurately practicing obstetricians (experts) can apply dating rules and compare the interpretation of gestation-sensitive ultrasound data with those of a computer system. SUBJECTS: Seventeen practicing obstetricians. Members of the Royal College of Obstetricians and Gynaecologists, from 14 different units throughout the UK. DESIGN: Six cases with menstrual and ultrasound data together with identical ultrasound charts and obstetric wheels. MAIN OUTCOME MEASURES: Concordance between the calculated estimated date of delivery (EDD) and growth assessment provided by the experts and the computer system. RESULTS: The calculation of the EDD by the experts was imprecise (59% within 3 days overall). Concordance with the computer calculation was poorest when the ultrasound measurements lay close to the upper or lower centile lines (average 7% within 3 days of the computer). Interpretation of growth showed good concordance with the computer when gestation was not critical to the interpretation (94%), but very poor when gestation was critical (7%). CONCLUSIONS: Calculation of EDD by means of an obstetric wheel and charts is not precise. Compared with the computer system, these errors have a significant effect on the subsequent interpretation of growth scans when the data are borderline. A computer system provides the more accurate method for interpreting gestation-sensitive ultrasound biometry.  (+info)

Can transvaginal fetal biometry be considered a useful tool for early detection of skeletal dysplasias in high-risk patients? (5/815)

OBJECTIVE: To evaluate the possibility of an early diagnosis of skeletal dysplasias in high-risk patients. METHODS: A total of 149 consecutive, uncomplicated singleton pregnancies at 9-13 weeks' amenorrhea, with certain menstrual history and regular cycles, were investigated with transvaginal ultrasound to establish the relationship between femur length and menstrual age, biparietal diameter and crown-rump length, using a polynomial regression model. A further eight patients with previous skeletal dysplasias in a total of 13 pregnancies were evaluated with serial examinations every 2 weeks from 10-11 weeks. RESULTS: A significant correlation between femur length and crown-rump length and biparietal diameter was found, whereas none was observed between femur length and menstrual age. Of the five cases with skeletal dysplasias, only two (one with recurrent osteogenesis imperfecta and one with recurrent achondrogenesis) were diagnosed in the first trimester. CONCLUSIONS: An early evaluation of fetal morphology in conjunction with the use of biometric charts of femur length against crown-rump length and femur length against biparietal diameter may be crucial for early diagnosis of severe skeletal dysplasias. By contrast, in less severe cases, biometric evaluation appears to be of no value for diagnosis.  (+info)

Caffeine consumption and menstrual function. (6/815)

The relation between caffeine intake and menstrual function was examined in 403 healthy premenopausal women who belonged to Kaiser Permanente Medical Care Program in 1990-1991. A telephone interview collected information about caffeinated beverage intake as well as other lifestyle, demographic, occupational, and environmental factors. Subjects collected daily urine samples and completed a daily diary for an average of five menstrual cycles. Metabolites of estrogen and progesterone were measured in the urine, each cycle was characterized as anovulatory or ovulatory, and a probable day of ovulation was selected when appropriate. Logistic regression and repeated measures analyses were performed on menstrual parameters. Women whose caffeine consumption was heavy (>300 mg of caffeine per day) had less than a third of the risk for long menses (> or =8 days) compared with women who did not consume caffeine (adjusted odds ratio = 0.30, 95% confidence interval 0.14-0.66). Those whose caffeine consumption was heavy also had a doubled risk for short cycle length (< or =24 days) (adjusted odds ratio = 2.00, 95% confidence interval 0.98-4.06); this association was also evident in those whose caffeine consumption was heavy who did not smoke (adjusted odds ratio = 2.11, 95% confidence interval 1.03-4.33). Caffeine intake was not strongly related to an increased risk for anovulation, short luteal phase (< or =10 days), long follicular phase (> or =24 days), long cycle (> or =36 days), or measures of within-woman cycle variability.  (+info)

Adhesion of shed menstrual tissue in an in-vitro model using amnion and peritoneum: a light and electron microscopic study. (7/815)

We have investigated the adhesion of endometrial tissue isolated from antegradely shed menstrual effluent to amnion and peritoneum. This endometrial tissue was cultured overnight on either side of intact and stripped amnion and on the mesothelial side of peritoneum. Light and electron microscopy were applied to evaluate adhesion. With light microscopy adhesion of endometrial fragments to stripped membranes was observed in nine out of 12 specimens and in 12 out of 13 specimens when layered on the extracellular matrix side of amnion. Adhesion when layered on the epithelial side was seen in only four out of 13 specimens. However, when using scanning electron microscopy adhesion of menstrual endometrial tissue could be visualized in all samples. Numerous adhering fragments were seen when layered on the extracellular matrix side of untreated amnion. On several occasions not only adhesion but also spreading of cells was observed. When layered on the epithelial side of untreated amnion or peritoneum, adhesion was exclusively seen at locations where the epithelium was damaged or absent. These findings were confirmed by transmission electron microscopy. These observations indicate that endometrial tissue isolated from antegradely shed menstrual effluent preferentially adheres to subepithelial structures of amnion and peritoneum. The lack of adhesion to epithelial cells suggests that an intact mesothelial lining prevents adhesion of menstrual endometrial tissue.  (+info)

Apoptosis of human endometrium mediated by perforin and granzyme B of NK cells and cytotoxic T lymphocytes. (8/815)

Endometrial stromal granulocytes (EGs) were found to be a major component of human endometrial stroma in the late secretory phase. However, the role of EGs in the mechanism of human endometrial menstruation has not been clarified. Immunohistochemistry of CD56, perforin, granzyme B, and vimentin, in situ detection of apoptosis by TUNEL (TdT-mediated dUTP-biotin nick and labeling) and electron microscopy were performed in endometrial tissue samples with normal menstrual cycles. We analyzed the number of immunostained cells in the functional layer of stroma and the number of apoptotic cells detected by TUNEL in the endometrial glandular cells. Double-staining revealed that CD56-positive endometrial stromal cells were simultaneously positive for both perforin and granzyme B, and negative for vimentin, which recognized stromal tissue. Vimentin was positive for the predecidual cells and negative for EGs. CD56-positive EGs involving perforin and granzyme B were progressively recruited during the secretory phases before menstruation. Apoptosis in endometrial glandular cells increased from the late secretory phase, which maximized at the menstrual period. This finding suggests that the cytotoxic granules released from EGs, which are derived from cytotoxic T lymphocytes and natural killer cells, are initiators of the apoptotic pathway that induces endometrial menstruation.  (+info)

• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10