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Human Myometrium (human + myometrium)

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Medical Sciences	85%

Selected Abstracts

Potassium Channels in the Human Myometrium

EXPERIMENTAL PHYSIOLOGY, Issue 2 2001
Raheela N. Khan
The contractility of the human uterus is under the fine control of a variety of interacting bioactive agents. During labour, the excitability of the uterus is drastically transformed in comparison with the non-labour state and is manifest at the membrane level via the acivity of uterine ion channels. This article reviews the contribution of potassium (K+) channels to human uterine excitability. [source]

ORIGINAL ARTICLE: Antigen-presenting Cells in Pregnant and Non-pregnant Human Myometrium

AMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 3 2010
Marina Ivanisevic
Citation Ivanisevic M, Segerer S, Rieger L, Kapp M, Dietl J, Kämmerer U, Frambach T. Antigen-presenting cells in pregnant and non-pregnant human myometrium. Am J Reprod Immunol 2010; 64: 188,196 Problem, Inflammatory cells play a crucial role in human parturition. Different populations of leucocytes invade the reproductive tract. Numerous studies have described the decidual immune cell population in pregnant and non-pregnant endometrium. However, little is known about the presence of immune cells in human myometrium. Method of study, We herein analysed a spectrum of immune cells in human myometrium comparing tissue samples from non-pregnant (n = 8) and pregnant (n = 10) uteri. Applying immunohistochemistry with a panel of antibodies specific for T cells, monocytes, natural killer cells, B cells and antigen-presenting cells (CD4, CD8, CD14, CD15, CD16, CD19, CD56, CD68, CD83, HLA-DR, DC-Sign, mast cell tryptase), we characterized the immune cell population of human myometrium. Results, A significantly higher number of CD14, CD15, CD16, DC-SIGN as well as CD4-positive cells were found in myometrium of pregnant compared to non-pregnant uteri, while mast cells were significantly reduced in pregnant myometrium. Conclusion, All markers found increased in pregnant myometrium indicate monocyte/macrophage lineage cells and thus suggest a possible involvement of these cells in healthy pregnancy maintenance. Monocytes/macrophages might produce a microenvironment that permits a controlled invasion of trophoblast cells into the myometrium while preventing a rejection of the semiallogenic conceptus and providing an important barrier against invading pathogenes. [source]

Regulation of Human Myometrial Contractility During Pregnancy and Labour: Are Calcium Homeostatic Pathways Important?

EXPERIMENTAL PHYSIOLOGY, Issue 2 2001
Rachel M. Tribe
If we are to develop new strategies for the treatment and management of preterm and dysfunctional term labour, it is imperative that we improve current understanding of the control of human uterine activity. Despite many studies of animal pregnancy, there is a paucity of knowledge relating to the complex control of human myometrium during pregnancy. It is hypothesized that human myometrium is relatively quiescent during the majority of pregnancy and that as term approaches there is cascade of molecular events that prepare the uterus for labour. This review will consider the cellular mechanisms involved in the regulation of human myometrial activity and the modulation of these by hormonal and mechanical signals. In particular, the contribution of calcium homeostatic pathways to the control of human myometrial contractility during gestation will be discussed. [source]

Inhibitory effects of desflurane and sevoflurane on oxytocin-induced contractions of isolated pregnant human myometrium

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 9 2005
K. Yildiz
Background:, In this study, we investigated the inhibitory effects of desflurane and sevoflurane on oxytocin-induced contractions of isolated human myometrium. Methods:, Following delivery of the infant and placenta, a small segment of myometrium was excised from the upper incisional surface of the lower uterine segment and 20 strips, randomly assigned into two groups (n = 10), were obtained from 20 non-laboring term parturients. The study protocol consisted of a 60-min period of spontaneous contractions, control recording with oxytocin 2 × 109 m (10-min period), washout interval of 10 min, volatile administration (three times per 15-min period) of 0.5, 1 and 2 minimum alveolar concentration (MAC), response to oxytocin (10-min period), a further washout interval (10-min period) and subsequent control recording with oxytocin without anesthetics. Results:, After oxytocin administration, the frequency and amplitude of contractions increased (P < 0.05) and the duration decreased (P < 0.05). The frequency and amplitude of contractions induced with oxytocin decreased significantly at 0.5, 1 and 2 MAC of desflurane and sevoflurane (P < 0.05). The amplitude of contractions was significantly different at 1 MAC between the two groups (P < 0.05). The duration of contractions at 2 MAC decreased in both groups (P < 0.05). Conclusions:, Desflurane and sevoflurane at 0.5, 1 and 2 MAC inhibit the frequency and amplitude of myometrial contractions induced with oxytocin in a dose-dependent manner. However, desflurane inhibits the amplitude less than sevoflurane at 1 MAC. We suggest that 0.5 MAC of both agents and 1 MAC of desflurane may be safely used in the presence of oxytocin following delivery of the infant and placenta during Cesarean section without fear of uterine atony and hemorrhage. [source]

ORIGINAL ARTICLE: Antigen-presenting Cells in Pregnant and Non-pregnant Human Myometrium

Activin ,A -subunit and activin receptors in human myometrium at term and during labour

BJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 8 2001
Michal Schneider-Kolsky
Objective To measure activin A content and to localise and semi-quantitate activin receptors in human myometrium at term and during labour. Design Myometrium was collected from non-pregnant women (n= 6), pregnant women at term not in labour (n= 6) and at term in labour (n= 6). Setting Monash Medical Centre, Melbourne, Australia. Main outcome measures Tissue lysates of myometrium were analysed for activin A content using an enzyme-linked immunosorbent assay and activin receptor proteins IA, IIA and IIB using Western hybridisation. Activin ,A -subunit and activin receptors were localised in myometrium by immunohistochemistry. Results Activin A was detected by ELISA in non-pregnant, pregnant and labouring myometrium. Levels were significantly higher in labouring myometrium. The three activin receptors IA, IIA and IIB were detected in all myometrial samples by Western hybridisation. Receptor IA was expressed in significantly higher levels in pregnant myometrium. Receptor IIA was very weakly expressed throughout. The expression of receptor IIB was similar in all three groups. Activin ,A -subunit and all three receptors were localised to the endothelial cells of myometrial blood vessels. Neither activin ,A -subunit nor any of the three activin receptors were immunolocalised to myometrial smooth muscle cells in the three groups. This result was confirmed by Western blotting for expression of activin receptors in isolated myometrial smooth muscle and microvascular endothelial cells. Conclusion The myometrium is not a target for activin A during late pregnancy or labour. However, activin A may have a role in the regulation of microvascular endothelial cell function in the myometrium. [source]

Contraction kinetics of isolated human myometrium during menstrual cycle and pregnancy

BJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 1 2000
Mikhail Tchirikov
Objective To investigate the interaction between actin and myosin in the myometrium by studying the contraction kinetics of isolated samples of human myometrium. Design Experimental and observational cross-sectional study. Setting Eppendorf University Hospital, Hamburg. Samples Myometrium samples were taken from women in the follicular phase (n= 6) or luteal phase (n= 6) of the menstrual cycle and during pregnancy at term (n= 25). Methods The frequency, extent and rate of force development were determined in spontaneously active myometrial preparations. From a resting force of 2 mN, sustained tonic contractions were induced by K+ -depolarisation (124 mM), or by protein kinase C activation (19.9 ,M indolactam). The steady force was reversibly interrupted by rapid length changes (100 Hz sinus vibrations lasting 1 s, 5% of muscle length). Extent (steady plateau), as well as rate of force increase after cessation of vibrations, were derived from bi-exponential functions fitted to the time course of force recovery. Results Frequency of spontaneous contractions was higher in the follicular phase [mean (SD) 18.3 contractions/hour (1.0)] than in the luteal phase [13.4 contractions/hour (8.1)] or in pregnancy at term [8.8 contractions/hour (7.6)]. During indolactam treatment, steady force in pregnancy at term was significantly increased [8.8 mN (4.0)], compared with the follicular phase [3.7 mN (0.9)]. Force recovery was distinctly slower in pregnancy at term during indolactam treatment [time constant 99.2 s (57.9); P < 0.005] than during K+ -depolarisation [time constant 29.1 s (5.9)], whereas in the follicular phase the rate of force recovery was faster with indolactam [16.8 s (7.1)] than with K+ depolarisation [24.4 s (5.9); P < 0.005]. Conclusions The responses of human myometrium to contraction stimuli differ according to the reproductive state. Membrane depolarisation causes similar responses in all myometrial strips. In contrast, near term stimulation of protein kinase C generates a large tonic force and slow contraction kinetics, whereas early in the menstrual cycle contraction kinetics are fast. [source]

Possible role of the protein kinase C/CPI-17 pathway in the augmented contraction of human myometrium after gestation

BRITISH JOURNAL OF PHARMACOLOGY, Issue 7 2003
Hiroshi Ozaki
Activation of protein kinase C (PKC) by phorbol 12,13-dibutylate (PDBu, 1 ,M) induced sustained contractions with no increase in [Ca2+]i in nonpregnant and pregnant human myometria. The contractile effects of PDBu in pregnant myometrium were much greater than those in nonpregnant myometrium, and the contractions in pregnant myometrium were accompanied by an increase in myosin light chain (MLC) phosphorylation at Ser19. The contraction induced by PDBu in pregnant myometrium was inhibited by the inhibitors of conventional PKC isoforms, bisindolylmaleimides and indolocarbazole, such as Go6976, Go6983, and Go6850 (1 ,M). LY333531 (1 ,M), a specific inhibitor of PKC,, also inhibited the PDBu-induced contraction in the pregnant myometrium. In the pregnant myometrium permeabilized with , -toxin, PDBu increased the contractions induced at fixed Ca2+ concentration (0.3 ,M) both in nonpregnant and pregnant myometria, indicating Ca2+ sensitization of contractile elements. Western immunoblot analysis indicated that pregnant myometrium contained PKC isozymes such as conventional PKC (,, ,, ,), novel PKC (,, ,, ,), and atypical PKC (, but not , and ,). RT-PCR and real-time RT-PCR analysis indicated that, among the conventional PKC, the levels of mRNA of , isoform in pregnant human myometrium were greater than those in nonpregnant myometrium. CPI-17 is a substrate for PKC, and the phosphorylated CPI-17 is considered to inhibit myosin phosphatase. The levels of CPI-17 mRNA and protein expression were also greater in the pregnant myometrium. These results suggest that the PKC-mediated contractile mechanism is augmented in human myometrium after gestation, and that this augmentation may be attributable to the increased activity of the , PKC isoform and CPI-17. British Journal of Pharmacology (2003) 140, 1303,1312. doi:10.1038/sj.bjp.0705552 [source]