Assessing Dutch women's experiences of labour and birth: adaptations and psychometric evaluations of the measures Mothers on Autonomy in Decision Making Scale, Mothers on Respect Index, and Childbirth Experience Questionnaire 2.0.

BACKGROUND: The Mothers Autonomy in Decision Making Scale (MADM) assesses women's autonomy and role in decision making. The Mothers on Respect Index (MORi) asseses women's experiences of respect when interacting with their healthcare providers. The Childbirth Experience Questionnaire 2.0 assesses the overall experience of childbirth (CEQ2.0). There are no validated Dutch measures of the quality of women's experiences in the intrapartum period. Therefore, the aim of this study was to evaluate the psychometric properties of these measures in their Dutch translations. METHODS: The available Dutch versions of the MADM and MORi were adapted to assess experiences in the intrapartum period. The CEQ2.0 was translated by using forward-backward procedures. The three measures were included in an online survey including items on individual characteristics (i.e. maternal, birth, birth interventions). Reliability was assessed by calculating Cronbach's alphas. Mann-Whitney, Kruskal Wallis or Student T-tests were applied where appropriate, to assess discrimination between women who differed on individual characteristics (known group validity). We hypothesized that women who experienced pregnancy complications and birth interventions would have statistically lower scores on the MADM, MORi and CEQ2.0, compared with women who had healthy pregnancies and physiological births. Convergent validity was assessed using Spearman Rank correlations between the MADM, MORi and/or CEQ2.0. We hypothesized moderate to strong correlations between these measures. Women's uptake of and feedback on the measures were tracked to assess acceptability and clarity. RESULTS: In total 621 women were included in the cross sectional study. The calculated Cronbach's alphas for the MADM, MORi and CEQ, were ≥ 0.77. Knowngroup validity was confirmed through significant differences on all relevant individual characteristics, except for vaginal laceration repair. Spearman Rank correlations ranged from 0.46-0.80. In total 98% of the included women out of the eligible population completed the MADM and MORi for each healthcare professional they encountered during childbirth. The proportions of MADM and MORi-items which were difficult to complete ranged from 0.0-10.8%, 0.6-2.7%, respectively. CONCLUSIONS: The results of our study showed that the Dutch version of the MADM, MORi and CEQ2.0 in Dutch are valid instruments that can be used to assess women's experiences in the intrapartum period.

Senescence bypass screen identifies TBX2, which represses Cdkn2a (p19(ARF)) and is amplified in a subset of human breast cancers.

To identify new immortalizing genes with potential roles in tumorigenesis, we performed a genetic screen aimed to bypass the rapid and tight senescence arrest of primary fibroblasts deficient for the oncogene Bmi1. We identified the T-box member TBX2 as a potent immortalizing gene that acts by downregulating Cdkn2a (p19(ARF)). TBX2 represses the Cdkn2a (p19(ARF)) promoter and attenuates E2F1, Myc or HRAS-mediated induction of Cdkn2a (p19(ARF)). We found TBX2 to be amplified in a subset of primary human breast cancers, indicating that it might contribute to breast cancer development.

Learning strategies during clerkships and their effects on clinical performance.

BACKGROUND: Previous research revealed relationships between learning strategies and knowledge acquisition. During clerkships, however, students' focus widens beyond mere knowledge acquisition as they further develop overall competence. This shift in focus can influence learning strategy use. AIM: We explored which learning strategies were used during clerkships and their relationship to clinical performance. METHODS: Participants were 113 (78%) clerks at the university hospital or one of six affiliated hospitals. Learning strategies were assessed using the 'Approaches to Learning at Work Questionnaire' (deep, surface-rational and surface-disorganised learning). Clinical performance was calculated by taking the mean of clinical assessment marks. The relationship between learning strategies and clinical performance was explored using regression analysis. RESULTS: Most students (89%) did not clearly prefer a single learning strategy. No relationship was found between learning strategies and clinical performance. DISCUSSION: Since overall competence comprises integration of knowledge, skills and professional behaviour, we assume that students without a clear preference use more than one learning strategy. Finding no relationship between learning strategies and clinical performance reflects the complexity of clinical learning. Depending on circumstances it may be important to obtain relevant information quickly (surface-rational) or understand material thoroughly (deep). In future research we will examine when and why students use different learning strategies.

The trithorax-group and polycomb-group chromatin modifiers: implications for disease.

The chromatin structure associated transcriptional memory function by Polycomb-group and trithorax-group protein complexes integrate normal development with control of cellular proliferation. This is illustrated by recent mechanistic insights that link Polycomb repression with histone deacetylases and the identification of new target genes that provide a connection to cell cycle control and tumorigenesis.

The Polycomb group--no longer an exclusive club?

Polycomb group (PcG) proteins maintain silencing at target loci in higher eukaryotes but recent evidence suggests that about half of these proteins are also required for maintenance of activation at homeotic loci. We suggest that PcG and trithorax group response elements should acquire a new name, 'maintenance elements', to reflect the dual function of regulatory elements that bind both groups of proteins. New data suggest that there might be a functional link between PcG repression and cell-cycle regulation.

Mice bearing the E mu-myc and E mu-pim-1 transgenes develop pre-B-cell leukemia prenatally.

Previously, it has been shown that E mu-pim-1 transgenic mice are predisposed to T-cell lymphomas, whereas E mu-myc transgenic mice are predisposed to pre-B-cell lymphomas. Here we show that double-transgenic E mu-myc E mu-pim-1 mice exhibit pre-B-cell leukemia in utero. Upon transplantation into recipient mice, embryo-derived double-transgenic leukemic cells frequently progressed to highly malignant monoclonal tumors, indicating that additional (epi)genetic events had occurred during the progression of the disease.

Interaction of mouse polycomb-group (Pc-G) proteins Enx1 and Enx2 with Eed: indication for separate Pc-G complexes.

The Polycomb group (Pc-G) constitutes an important, functionally conserved group of proteins, required to stably maintain inactive homeobox genes repressed during development. Drosophila extra sex combs (esc) and its mammalian homolog embryonic ectoderm development (eed) are special Pc-G members, in that they are required early during development when Pc-G repression is initiated, a process that is still poorly understood. To get insight in the molecular function of Eed, we searched for Eed-interacting proteins, using the yeast two-hybrid method. Here we describe the specific in vivo binding of Eed to Enx1 and Enx2, two mammalian homologs of the essential Drosophila Pc-G gene Enhancer-of-zeste [E(z)]. No direct biochemical interactions were found between Eed/Enx and a previously characterized mouse Pc-G protein complex, containing several mouse Pc-G proteins including mouse polyhomeotic (Mph1). This suggests that different Pc-G complexes with distinct functions may exist. However, partial colocalization of Enx1 and Mph1 to subnuclear domains may point to more transient interactions between these complexes, in support of a bridging role for Enx1.

Identification and characterization of interactions between the vertebrate polycomb-group protein BMI1 and human homologs of polyhomeotic.

In Drosophila melanogaster, the Polycomb-group (PcG) genes have been identified as repressors of gene expression. They are part of a cellular memory system that is responsible for the stable transmission of gene activity to progeny cells. PcG proteins form a large multimeric, chromatin-associated protein complex, but the identity of its components is largely unknown. Here, we identify two human proteins, HPH1 and HPH2, that are associated with the vertebrate PcG protein BMI1. HPH1 and HPH2 coimmunoprecipitate and cofractionate with each other and with BMI1. They also colocalize with BMI1 in interphase nuclei of U-2 OS human osteosarcoma and SW480 human colorectal adenocarcinoma cells. HPH1 and HPH2 have little sequence homology with each other, except in two highly conserved domains, designated homology domains I and II. They share these homology domains I and II with the Drosophila PcG protein Polyhomeotic (Ph), and we, therefore, have named the novel proteins HPH1 and HPH2. HPH1, HPH2, and BMI1 show distinct, although overlapping expression patterns in different tissues and cell lines. Two-hybrid analysis shows that homology domain II of HPH1 interacts with both homology domains I and II of HPH2. In contrast, homology domain I of HPH1 interacts only with homology domain II of HPH2, but not with homology domain I of HPH2. Furthermore, BMI1 does not interact with the individual homology domains. Instead, both intact homology domains I and II need to be present for interactions with BMI1. These data demonstrate the involvement of homology domains I and II in protein-protein interactions and indicate that HPH1 and HPH2 are able to heterodimerize.

Retroviral insertional mutagenesis: past, present and future.

Retroviral insertion mutagenesis screens in mice are powerful tools for efficient identification of oncogenic mutations in an in vivo setting. Many oncogenes identified in these screens have also been shown to play a causal role in the development of human cancers. Sequencing and annotation of the mouse genome, along with recent improvements in insertion site cloning has greatly facilitated identification of oncogenic events in retrovirus-induced tumours. In this review, we discuss the features of retroviral insertion mutagenesis screens, covering the mechanisms by which retroviral insertions mutate cellular genes, the practical aspects of insertion site cloning, the identification and analysis of common insertion sites, and finally we address the potential for use of somatic insertional mutagens in the study of nonhaematopoietic and nonmammary tumour types.

BMI-1 gene amplification and overexpression in hematological malignancies occur mainly in mantle cell lymphomas.

The BMI-1 gene is a putative oncogene belonging to the Polycomb group family that cooperates with c-myc in the generation of mouse lymphomas and seems to participate in cell cycle regulation and senescence by acting as a transcriptional repressor of the INK4a/ARF locus. The BMI-1 gene has been located on chromosome 10p13, a region involved in chromosomal translocations in infant leukemias, and amplified in occasional non-Hodgkin's lymphomas (NHLs) and solid tumors. To determine the possible alterations of this gene in human malignancies, we have examined 160 lymphoproliferative disorders, 13 myeloid leukemias, and 89 carcinomas by Southern blot analysis and detected BMI-1 gene amplification (3- to 7-fold) in 4 of 36 (11%) mantle cell lymphomas (MCLs) with no alterations in the INK4a/ARF locus. BMI-1 and p16INK4a mRNA and protein expression were also studied by real-time quantitative reverse transcription-PCR and Western blot, respectively, in a subset of NHLs. BMI-1 expression was significantly higher in chronic lymphocytic leukemia and MCL than in follicular lymphoma and large B cell lymphoma. The four tumors with gene amplification showed significantly higher mRNA levels than other MCLs and NHLs with the BMI-1 gene in germline configuration. Five additional MCLs also showed very high mRNA levels without gene amplification. A good correlation between BMI-1 mRNA levels and protein expression was observed in all types of lymphomas. No relationship was detected between BMI-1 and p16INK4a mRNA levels. These findings suggest that BMI-1 gene alterations in human neoplasms are uncommon, but they may contribute to the pathogenesis in a subset of malignant lymphomas, particularly of mantle cell type.

Context-dependent actions of Polycomb repressors in cancer.

Polycomb Group (PcG) proteins form Polycomb Repressive Complexes (PRCs) that function as epigenetic repressors of gene expression. The large variety of PcG proteins, in addition to the high number of paralogs, allows for the formation of diverse PRCs with different properties, providing fine-tuned control over cell specification. Initially identified as being oncogenes, a small number of PcG genes are involved in tumor development in part through the repression of the CDKN2A locus. Therefore, enhanced PcG-mediated repression has long been assumed to be cancer promoting. However, recent data have revealed that for some cancers, PcG proteins act as tumor suppressors, indicating that this traditional view is oversimplified. In this review, we present an overview of the roles of PcG genes in oncogenesis and how the nature of their role is context dependent.

Pertubation of B and T cell development and predisposition to lymphomagenesis in Emu Bmi1 transgenic mice require the Bmi1 RING finger.

Proviral activation of the Bmi1 gene has implicated Bmi1 as a collaborator of c-Myc in lymphomagenesis. To determine the effect of Bmi1 overexpression on hematopoiesis and lymphomagenesis transgenic mice were generated that overexpress different forms of the Bmi1 protein in their lymphoid compartment. Emu Bmi1 transgenic mice, overexpressing the wild type Bmi1 protein showed a perturbed lymphoid development and were highly susceptible to B and T cell lymphomagenesis. Mutational analysis of the Bmi1 protein demonstrated that the conserved N-terminal RING finger and central part of Bmi1 are essential for its oncogenic potential whereas the C-terminal Pro-Ser rich region is not required. We have used provirus tagging in the Emu Bmi1 mice to identify genes that cooperate with Bmi1 in lymphomagenesis. MoMLV infection in Emu Bmi1 transgenic mice accelerated lymphoma development. Proviral activation of the Pim and Myc genes but not the Gfi1 gene were frequently observed in these tumors. These results demonstrate that Bmi1 is a potent oncogene and suggest that it plays an important role in early lymphoid development.

MPc2, a new murine homolog of the Drosophila polycomb protein is a member of the mouse polycomb transcriptional repressor complex.

The evolutionarily conserved polycomb and trithorax-group genes are required to maintain stable expression patterns of homeotic genes and other target genes throughout development. Here, we report the cloning and characterization of a novel mouse polycomb homolog, MPc2, in addition to the previously described M33 polycomb gene. Co-immunoprecipitations and subnuclear co-localization studies show that MPc2 interacts with the mouse polycomb-group oncoprotein Bmi1 and is a new member of the mouse polycomb multiprotein complex. Gal4DB-MPc2 or -M33 fusion proteins mediate a five- to tenfold repression of stably integrated reporter constructs carrying GAL4 binding sites, demonstrating that these proteins are transcriptional repressors. The MPc2 gene is localized on chromosome 11, in close proximity to the classical mouse mutations tail short (Ts) and rabo torcido (Rbt). Ts and Rbt hemizygous mice display anemia and transformations of the axial skeleton reminiscent of phenotypes observed in mice with mutated polycomb or trithorax-group genes, suggesting that MPc2 is a candidate gene for Ts and Rbt.

High expression of Polycomb group protein EZH2 predicts poor survival in salivary gland adenoid cystic carcinoma.

BACKGROUND: The prognosis of adenoid cystic carcinoma (ACC), a malignant salivary gland tumour, depends on clinicopathological parameters. To decipher the biological behaviour of ACC, and to identify patients at risk of developing metastases, additional markers are needed. METHODS: Expression of the cell cycle proteins p53, cyclin D1, p16(INK4a), E2F1 and Ki-67, together with the Polycomb group (PcG) proteins BMI-1, MEL-18, EZH2 and EED was investigated immunohistochemically 21 formalin-fixed, paraffin-embedded primary ACCs in relation to tumour characteristics. RESULTS: ACC revealed significantly increased expression of the cell cycle proteins compared to normal salivary tissue (n = 17). Members of the two PcG complexes displayed mutually exclusive expression in normal salivary gland tissue, with BMI-1 and MEL-18 being abundantly present. In ACC, this expression pattern was disturbed, with EZH2 and EED showing significantly increased expression levels. In univariate analysis, presence of recurrence, poor differentiation and high EZH2 levels (>25% immunopositivity) significantly correlated with unfavourable outcome. ACCs with high proliferative rate (>25% Ki-67 immunopositivity) significantly correlated with high levels of EZH2 and p16. Only the development of recurrence was an independent prognostic factor of survival in multivariate analysis. CONCLUSIONS: Expression of PcG complexes and of essential cell cycle proteins is highly deregulated in ACC. Also, EZH2 expression has prognostic relevance in this malignancy.

In vitro genetic screen identifies a cooperative role for LPA signaling and c-Myc in cell transformation.

c-Myc drives uncontrolled cell proliferation in various human cancers. However, in mouse embryo fibroblasts (MEFs), c-Myc also induces apoptosis by activating the p19Arf tumor suppressor pathway. Tbx2, a transcriptional repressor of p19Arf, can collaborate with c-Myc by suppressing apoptosis. MEFs overexpressing c-Myc and Tbx2 are immortal but not transformed. We have performed an unbiased genetic screen, which identified 12 oncogenes that collaborate with c-Myc and Tbx2 to transform MEFs in vitro. One of them encodes the LPA2 receptor for the lipid growth factor lysophosphatidic acid (LPA). We find that LPA1 and LPA4, but not LPA3, can reproduce the transforming effect of LPA2. Using pharmacological inhibitors, we show that the in vitro cell transformation induced by LPA receptors is dependent on the Gi-linked ERK and PI3K signaling pathways. The transforming ability of LPA1, LPA2 and LPA4 was confirmed by tumor formation assays in vivo and correlated with prolonged ERK1/2 activation in response to LPA. Our results reveal a direct role for LPA receptor signaling in cell transformation and tumorigenesis in conjunction with c-Myc and reduced p19Arf expression.

The polycomb group proteins, BMI-1 and EZH2, are tumour-associated antigens.

We used SEREX technology to identify novel tumour-associated antigens in patients with primary hepatocellular carcinoma and found serological responses to the polycomb group (PcG) protein BMI-1, which is overexpressed in a range of different tumour types. Further studies identified T-cell responses to both BMI-1 and another PcG protein, EZH2, in cancer patients and at relatively lower levels in some normal donors. We next identified several CD8+ T-cell epitopes derived from BMI-1 and EZH2 and demonstrated that EZH2-derived peptides elicited more significant interferon-gamma (IFN-gamma) release than BMI-1-derived peptides. That CD8(+) T cells were responsible for the observed responses was confirmed for EZH2 by both IFN-gamma capture assays and tetramer staining using an HLA-A0201-restricted, EZH2-derived YMSCSFLFNL (aa 666-674) epitope. The ability of YMSCSFLFNL (aa 666-674) to stimulate the in vitro expansion of specific T cells from peripheral blood lymphocytes was greatly enhanced when the CD25(+) T-cell population was depleted. EZH2-specific cytotoxic T lymphocyte clones specific for two HLA-A0201 epitopes were generated and found to recognise endogenously processed EZH2 in both HLA-matched fibroblasts and tumour cell lines. Given the widespread overexpression of PcG proteins in cancer and their critical role in oncogenesis, these data suggest that they may be useful targets for cancer immunotherapy.

Functional analysis of mouse Polycomb group genes.

Two groups of genes, the Polycomb group (Pc-G) and trithorax group (trx-G), have been identified in Drosophila to provide a transcriptional memory mechanism. They ensure the maintenance of transcription patterns of key regulators such as the Hox genes and thereby the correct execution of developmental programmes. Recent data suggest that this memory mechanism is conserved in vertebrates and plants. Here we discuss current insights into the role of mouse Pc-G genes, with a particular focus on the best-studied Bmi1, Mel18 and M33 genes, as representative examples. Common phenotypes observed in knockout mice mutant for each of these genes indicate an important role for Pc-G genes not only in regulation of Hox gene expression and axial skeleton development but also in control of proliferation and survival of haematopoietic cell lineages. Proliferation defects are also observed in other cell lineages derived from these null-mutant mice, and provide new tools to study the impact of Pc-G deregulation on cell cycle control.

Cellular memory of transcriptional states by Polycomb-group proteins.

The Polycomb-group constitutes an important, widely conserved group of transcriptional repressors best known for their function in stably maintaining the inactive expression patterns of key developmental regulators, including homeotic genes. Together with the counteracting trithorax-group proteins, they establish a form of cellular memory by faithfully maintaining transcription states determined early in embryogenesis. Besides being crucial for the correct execution of developmental programs, Polycomb-group mediated silencing also appears to be involved in controlling cell proliferation. Here we discuss several aspects of Pc-G function: target gene specificity and recognition as well as propagation of inactive chromatin states to subsequent cell generations.

Sequence similarity between the mammalian bmi-1 proto-oncogene and the Drosophila regulatory genes Psc and Su(z)2.

The bmi-1 proto-oncogene can be activated by Moloney murine leukaemia proviral insertions in E mu-myc transgenic mice. It encodes a highly conserved nuclear protein of 324 amino acids which belongs to a family of proteins containing a putative new zinc-finger. Another closely related member of this family is the mouse protein Mel-18. Here we report on the cloning and characterization of a homologous gene (D-bmi) from Drosophila melanogaster. Our analysis indicates that distinct domains of the mouse Bmi-1 protein, including the putative zinc-finger motif, are highly conserved within the much larger D-Bmi protein. Chromosomal localization and sequence comparison reveal that D-bmi is identical to Posterior Sex Combs (Psc) and indicate that the conserved domains between mouse bmi and Psc are also conserved within Suppressor-2 of Zeste (Su(z)2).