Pregnancy-associated venous thrombosis

Pregnant women are at an increased risk of venous thromboembolism (VTE) and the consequences of an acute event in pregnancy can be debilitating, long-lasting or fatal. Screening for risk factors early in pregnancy and the provision of thromboprophylaxis are useful ways of preventing VTE in some women, but even when performed diligently, acute events are likely to remain common for the foreseeable future. It is therefore important for obstetric and non-obstetric clinicians to recognize the symptoms and signs of deep vein thrombosis and pulmonary embolism in pregnancy, to understand how a diagnosis can be reached in an effective yet safe manner and to be aware of the available treatment modalities.

Human epidermal neural crest stem cells (hEPI-NCSC)--characterization and directed differentiation into osteocytes and melanocytes

Here we describe the isolation, characterisation and ex-vivo expansion of human epidermal neural crest stem cells (hEPI-NCSC) and we provide protocols for their directed differentiation into osteocytes and melanocytes. hEPI-NCSC are neural crest-derived multipotent stem cells that persist into adulthood in the bulge of hair follicles. Multipotency and self-renewal were determined by in vitro clonal analyses. hEPI-NCSC generate all major neural crest derivatives, including bone/cartilage cells, neurons, Schwann cells, myofibroblasts and melanocytes. Furthermore, hEPI-NCSC express additional neural crest stem cell markers and global stem cell genes. To variable degrees and in a donor-dependent manner, hEPI-NCSC express the six essential pluripotency genes C-MYC, KLF4, SOX2, LIN28, OCT-4/POU5F1 and NANOG. hEPI-NCSC can be expanded ex vivo into millions of stem cells that remain mulitpotent and continue to express stem cell genes. The novelty of hEPI-NCSC lies in the combination of their highly desirable traits. hEPI-NCSC are embryonic remnants in a postnatal location, the bulge of hair follicles. Therefore they are readily accessible in the hairy skin by minimal invasive procedure. hEPI-NCSC are multipotent somatic stem cells that can be isolated reproducibly and with high yield. By taking advantage of their migratory ability, hEPI-NCSC can be isolated as a highly pure population of stem cells. hEPI-NCSC can undergo robust ex vivo expansion and directed differentiation. As somatic stem cells, hEPI-NCSC are conducive to autologous transplantation, which avoids graft rejection. Together, these traits make hEPI-NCSC novel and attractive candidates for future cell-based therapies and regenerative medicine.

Emergency caesarean section: influences on the decision-to-delivery interval

RCOG/NICE guidelines recommend that, for fetal compromise in labour, delivery should be accomplished ideally within 30 minutes. In this study, we investigated the factors which affect the decision-to-delivery (DD) intervals for emergency caesareans. To achieve this, prospective data were collected for all grade 1 and 2 caesareans performed on a busy labour ward over 12 months. We found that the ratio of labouring women to midwives had a significant effect on the DD intervals, which were significantly prolonged when 1 : 1 care was not provided (P < 0.001). The observed effect resulted exclusively from a prolonged transfer time to theatre. General anesthesia use shortened the DD interval for grade 1 caesareans (P < 0.001) and was more likely to be used during the day shift (P < 0.009). We conclude that midwifery staffing levels and the form of anaesthesia employed influence on DD intervals for the most urgent caesarean sections.

Epigenetic modulation of the protein kinase A RIIα (PRKAR2A) gene by histone deacetylases 1 and 2 in human smooth muscle cells

Recently we reported that the expression of the protein kinase A (PKA) regulatory subunit RIIα is dynamically regulated in human smooth muscle cells of the uterus. We showed that expression levels of mRNA/protein were substantially increased during pregnancy and decreased upon labour, changes that were mirrored by particulate type II PKA activity. This implied an important role for RIIα in maintaining uterine quiescence during pregnancy. Consequently the purpose of the present study was to identify potential mechanisms by which expression of the RIIα gene was regulated in this tissue. We indicate here that the three SpI-III (GC) binding domains within the proximal promoter region of the human RIIα gene may play important roles in modulating expression of the gene in human myometrial cells. We show that all three GC binding domains are involved in binding Sp1, Sp3, histone deacetylase (HDACs) 1/2 and RbAp48 transcriptional complexes. The functional significance of these binding domains was further analysed employing in vitro luciferase reporter assays with full-length/truncated RIIα promoter constructs. Importantly we show that treatment of primary human myometrial cell cultures with the general class I/II HDAC inhibitor trichostatin A results in an increase in mRNA/protein levels. Moreover the increase in mRNA levels appeared to be preceded by an increase in aH3, PolIIa, Sp3 and HDAC 2 binding to the three SpI-III (GC) binding sites within the RIIα promoter. These results enable us to provide a model whereby RIIα expression is epigenetically regulated in human myometrial smooth muscle cells by histone deacetylase(s) activity within the GC-rich proximal promoter region of the gene.

Characterization of cellular retinoid-binding proteins in human myometrium during pregnancy

Many complementary or competing signalling pathways bear an influence on the myometrium at any one time, and because the retinoic acid signalling pathway influences differentiation of a wide array of human tissues, this may be one of the determinants of myometrial differentiation during pregnancy. We have explored the novel hypothesis that the retinoids may act as important regulators in controlling the differentiated state of the human myometrium during pregnancy by characterizing the expression profiles for cellular retinoid-binding proteins CRBPI, CRABPI and CRABPII in non-pregnant, pregnant (non-labouring) and labouring human myometrium taken from the functionally distinct upper and lower uterine segments. In addition, we have investigated the effect of all-trans retinoic acid (ATRA) on the expression of several retinoic acid response genes including cyclooxygenase-2 (COX-2) and connexin-43 (Cx-43). Different spatial and temporal patterns of expression were observed for CRBPI, CRABPI and CRABPII within the upper and lower uterine segments through the three trimesters of pregnancy and in labour. Furthermore, the expression of COX-2, Cx-43, CRABPI, the transcription factor c-Jun and the retinoic acid receptor RARbeta altered in response to different concentrations of ATRA, suggesting that the differential expression of cellular retinoid-binding proteins may lead to different levels of retinoic acid being delivered to its nuclear targets, leading to the differential expression of specific target genes within the myometrium during pregnancy.

Nuclear retinoid receptor expression in normal human endometrium throughout the menstrual cycle

Previous work has shown that retinoic acid receptors (RARs) and retinoid X receptors (RXRs) are expressed in human endometrial epithelial and stromal cells. These nuclear receptors mediate the biological effects of retinoic acid, a vitamin A derivative which may have an important, though poorly characterized role in the functional differentiation of secretory epithelia. The aim of this study was to find out whether the expression of RAR and RXR mRNA in endometrial epithelial and stromal cells varies in relation to the menstrual cycle. The expression of RARs and RXRs was investigated by Northern blotting and, for stromal cells, there were no differences in expression of RAR-alpha, RAR-beta, RAR-gamma and RXR-alpha between the proliferative and secretory phases of the menstrual cycle. Similarly, for epithelial tissue, there were no significant differences between the proliferative and secretory phases with respect to the expression of RAR-alpha, RAR-gamma and RXR-alpha. However, RAR-beta was expressed at a 1.7-fold higher level in epithelial samples from the proliferative phase compared to the secretory phase. Overall, the levels of expression of RAR-alpha, RAR-beta and RAR-gamma were 1.7- to 4-fold higher in stromal cells compared to epithelial cells whereas RXR-alpha was expressed at a similar level in both cell types. We have previously suggested that retinoic acid has a role in endometrial differentiation or function which may be reflected by cyclical changes in intracellular retinoic acid levels. These data indicate that RARs and RXRs are expressed at a similar level throughout the menstrual cycle, with the possible exception of RAR-beta, implying that any menstrual cycle-related function of RARs in controlled by ligand availability rather than by changes in expression of the receptors.

Menstrual cycle related differences in the proliferative responses of cultured human endometrial stromal cells to retinoic acid

Although ovarian-derived steroid hormones are central to the control of endometrial growth and secretory differentiation, all-trans retinoic acid, a derivative of vitamin A, may also play an important role. Since the retinoids can inhibit the proliferation of both fibroblasts and epithelial cells in experimental systems, we investigated whether the proliferation of endometrial stromal cells was inhibited by all-trans retinoic acid. A sensitive spectrophotometric assay was used to show that the proliferation rates of primary cultures of endometrial stromal fibroblasts varied with the timing of biopsy, and that all-trans retinoic acid inhibited the growth of late secretory phase cells but had no effect on cells sampled at other times. Furthermore, since the expression of mRNA encoding cellular retinoic acid binding protein type II decreases in endometrial stromal cells in the secretory phase, a rise in intracellular all-trans retinoic acid concentrations could be fundamental to the control of endometrial stromal cell proliferation and differentiation in vivo.

Variation in the expression of cellular retinoid binding proteins in human endometrium throughout the menstrual cycle

Human endometrium is a glandular epithelial tissue with a substantial underlying stroma. Under the influence of ovarian steroids, endometrium undergoes a cyclical pattern of proliferation followed by secretory differentiation. Since retinoids promote the differentiation of many epithelia to secretory phenotypes they may be involved in controlling the secretory differentiation of human endometrial epithelium. Cytosolic binding proteins for retinol (cellular retinol binding protein) and retinoic acid (cellular retinoic acid binding protein) may play an important part in regulating the availability of retinoic acid to its nuclear receptors and we have therefore asked whether expression of mRNA for these proteins varies in relation to endometrial differentiation. In a series of 54 endometrial biopsies, both endometrial epithelial and stromal cells expressed mRNA for cellular retinol binding protein type I at a constant level throughout the menstrual cycle. Cellular retinoic acid binding protein type II was also expressed but the level of expression varied dramatically, being elevated in the proliferative phase and depressed during the secretory phase of the menstrual cycle in both epithelial and stromal cells. These data suggest that cytosolic binding proteins modulate the supply of retinoic acid to the nuclei of endometrial cells during the menstrual cycle and that retinoic acid is involved in the cyclical control of endometrial differentiation.