Uterine contraction

Preterm birth (PTB) is a major public health problem, with a global prevalence of 9.6% and over a million annual neonatal deaths. In a mouse model of preterm labor (PTL) induced by intravaginal administration of a subclinical dose of lipopolysaccharide (LPS), we previously demonstrated that LPS ascends to the cervix, inducing complement activation, cervical remodeling and PTL. Here we show that complement activation also plays a role in myometrial contractions during PTL in this model. Increased levels of C5a were detected in the myometrium of LPS-treated mice but not in age-matched control or term myometrium. Human and mouse myometrium incubated with C5a showed increased frequency of contractions and expression of connexin 43, suggesting that C5a is an uterotonic molecule. Statins, which showed beneficial effects in preventing complement-mediated pregnancy complications, prevented cervical remodeling, myometrial contractions and PTL in the LPS model. The protective effects of stati...

Continuous fetal heart rate (FHR) monitoring and routine fetal scalp blood sampling was utilized in the evaluations of 366 fetuses during labor. One hundred and six patients had meconium in the amniotic fluid at some time during labor. A total of 26,110 uterine contractions were monitored during these 366 labors. The incidence of FHR patterns as a percentage of uterine contractions was calculated for the meconium and nonmeconium groups. Although there was a 3 1/2-fold increase in the incidence of low five-minute Apgar scores (less than 7) in the meconium group, signs of fetal distress were, with rare esception, not significantly different from those in the nonmeconium group. The presence of meconium in the amniotic fluid without signs of fetal asphyxia (late decelerations and acidosis) is not a sign of fetal distress and need not be an indication for active intervention. The combination of fetal asphyxia and meconium staining of the amniotic fluid, however, does enhance the potentia...

Background: Hydrotherapy (immersion or bathing) is used worldwide to promote relaxation and decrease parturient anxiety and pain in labor, but the psychophysiological effects of this intervention remain obscure. Design: A pretest—posttest design with repeated measures was used to examine the effects of hydrotherapy on maternal anxiety and pain, neuroendocrine responses, plasma volume shift (PVS), and uterine contractions (CXs) during labor. Correlations among variables were examined at three time points (preimmersion and twice during hydrotherapy). Methods: Eleven term women (mean age 24.5 years) in spontaneous labor were immersed to the xiphoid in 37 °C water for 1 hr. Blood samples and measures of anxiety and pain were obtained under dry baseline conditions and repeated at 15 and 45 min of hydrotherapy. Uterine contractions were monitored telemetrically. Results: Hydrotherapy was associated with decreases in anxiety, vasopressin (V), and oxytocin (O) levels at 15 and 45 min (all p...

Studies made on aqueous root extract of Selayak Hitam, a plant alleged to possess abortifacient activity in pregnant mothers established that the extract is teratogenic and did in fact cause abortion in mice. It was also observed that the aqueous root extract is relatively toxic as judged by the number of deaths occuring following administration of the extract. The mechanism by which abortion is brought about is unknown but it is possible that the abortifacient effect is due to the induced teratogenic activity, brought about by the extract.

Venom immunotherapy (VIT) is an efficient treatment modality for preventing further sting-induced anaphylactic reactions in patients with Hymenoptera venom allergy. The main side effects of VIT include local and systemic allergic reactions with a variable risk of up to 46%. We report the case of a woman who experienced rapid-onset hypocalcemia and regular uterine contractions on 3 occasions within 30 minutes of receiving Apis mellifera VIT. To the best of our knowledge, this is the first report of uterine contractions as a side effect of VIT. The importance of this event is clear, as VIT has now been approved for pregnant women. We provide recommendations to physicians using this modality.

Several compounds of the chemical class arylethanolamines have been shown to possess combined alpha- or vasodilator and beta-adrenoceptor blocking properties. The first drug was labetalol (AH5158)[5-(1-hydroxy-2)1-methyl-3-phenylpropyl(amino)-ethyl (salicylamide)]. Others include medroxalol, bucindolol and YM-09538, which differ from labetalol either by the nature of the substitution on the primary benzene ring and/or on the terminal nitrogen. All of these drugs are non-selective beta-blockers, except for bucindolol whose selectivity has not been carefully defined. The rationale for the development of this group of drugs was the knowledge that blockade of one adrenoceptor subtype causes reflex stimulation of the other, i.e. vasoconstriction after nonspecific beta-blockade and tachycardia after alpha-blockade. Since both of these compensatory responses act to prevent a fall in blood pressure, a relatively weak blockade of both receptor types should act synergistically to produce a lo...

Molecular mechanisms involved in uterine quiescence during gestation and those responsible for induction of labor at term are incompletely known. More than 10% of babies born worldwide are premature and 1,000,000 die annually. Preterm labor results in preterm delivery in 50% of cases in the United States explaining 75% of fetal morbidity and mortality. There is no Food and Drug Administration-approved treatment to prevent preterm delivery. Nitric oxide-mediated relaxation of human uterine smooth muscle is independent of global elevation of cGMP following activation of soluble guanylyl cyclase. S-nitrosation is a likely mechanism to explain cGMP-independent relaxation to nitric oxide and may reveal S-nitrosated proteins as new therapeutic targets for the treatment of preterm labor. Employing S-nitrosoglutathione as an nitric oxide donor, we identified 110 proteins that are S-nitrosated in 1 or more states of human pregnancy. Using area under the curve of extracted ion chromatograms a...

The effects of diltiazem and six bisbenzyltetrahydroisoquinoline alkaloids (antioquine, 7-O-methylantioquine, dimethylantioquine, monterine, granjine and cordobimine) were studied in rat isolated uterus in order to clarify the mechanisms of their relaxant actions. All the ...

The signals and mechanisms that synchronize the timing of human parturition remain a mystery and a better understanding of these processes is essential to avert adverse pregnancy outcomes. Although our insights into human labor initiation have been informed by studies in animal models, the timing of parturition relative to fetal maturation varies among viviparous species, indicative of phylogenetically different clocks and alarms; but what is clear is that important common pathways must converge to control the birth process. For example, in all species, parturition involves the transition of the myometrium from a relaxed to a highly excitable state, where the muscle rhythmically and forcefully contracts, softening the cervical extracellular matrix to allow distensibility and dilatation and thus a shearing of the fetal membranes to facilitate their rupture. We review a number of theories promulgated to explain how a variety of different timing mechanisms, including fetal membrane cel...

The aim of this in vitro study was to compare the uterokinetic activity of oxytocin and dinoprost, the natural PGF2α, with or without aglepristone, in canine myometrial fibers. Thirty-three bitches were allocated into one of four groups, depending on their estrous stage and whether or not they had received a treatment with aglepristone (metestrus aglepristone, n = 5; metestrus without treatment, n = 9; anestrus aglepristone, n = 9; anestrus without treatment, n = 10). After hysterectomy, longitudinal and circular uterine strips were mounted in organ baths. Oxytocin or PGF2α (10 nmol/l to 10 micromol/l) were applied non-cumulatively. A linear mixed effects models theory was used to compare the fiber effect, the aglepristone effect, and the treatment effect, from the area under the curves calculated from the contractile effect/concentration curves for each drug. Oxytocin and PGF2α induced concentration-dependent myometrial contractions in longitudinal (LF) and circular myometrial fibers (CF), indicating the presence of functional contractile oxytocin- and PGF2α-receptors in metestrus and anestrus. The contractile response to oxytocin was greater in LF than in CF in all of the groups; the response to PGF2α was greater in LF than in CF in non-treated bitches in anestrus and in treated bitches in metestrus. These results suggest that there is a difference in sensitivity or a heterogeneous distribution of oxytocin and PGF2α-receptors in the myometrial layers, which is independent of hormonal impregnation. The contractile response to oxytocin and PGF2α was significantly increased after aglepristone treatment in LF during metestrus, suggesting that the progesterone withdrawal induced by aglepristone has a role to play. The longitudinal myometrial layer also appeared to be the target for the two drugs at this stage. This study provides new information about canine uterine contractile activity, notably the differing behavior of myometrial CF and LF; in vivo studies are required to test the use of a combination of aglepristone and oxytocin in the treatment of canine pyometra.

The aim of this study is to simulate the contraction phenomena in pregnant uterine. Differential equations are used to model the uterine contractions for three states, namely contracting, refractory, and resting. Since verification and validation are vital for simulation ...

The aim of this study was to investigate whether apamin-sensitive K(+)channels play a role in the NO induced relaxation of the human pregnant myometrium. Concentration-response curves for sodium nitroprusside (SNP) (10(-9)-10(-4)M) were constructed in the absence and presence of 10(-8)M apamin and 10(-7)M charybdotoxin (CTX). Preincubation with apamin resulted in a significant attenuation of the relaxation caused by SNP, while pre-treatment with CTX insignificantly decreased the SNP induced relaxation. Our findings suggest that apamin-sensitive K(+)channels exist in the human pregnant myometrium and play a role in modulation of the myometrium response to NO donors