Systematic review of non-pharmacologic interventions to delay functional decline in community-dwelling patients with dementia.

OBJECTIVES: Older adults with dementia experience progressive functional decline, which contributes to caregiver burden and nursing home placement. The goal of this systematic review was to determine if any non-pharmacologic interventions have delayed functional decline among community-dwelling dementia patients. METHOD: We completed a systematic literature review to identify controlled clinical trials reporting the impact of non-pharmacologic interventions on any measure of functional impairment or disability among community-dwelling dementia patients. We included studies that reported any proxy-respondent, self-reported, or performance-based standardized assessments. RESULTS: We identified 18 published clinical trials that met inclusion criteria and found that study interventions fell into three different groups: occupational therapy, exercise, and multi-faceted ("other") interventions. The three groups of studies tended to vary systematically regarding the conceptual framework for the disabling process, target of intervention, and type of outcome measure. Approximately half the studies were conducted in the United States with mean sample size of 99 (from 27 to 1131) and follow-up periods between three months and two years. Instruments used to measure functional impairment or disability varied widely with 55 instruments across 18 studies. Nine studies reported a statistically significant improvement in functional decline in the intervention group. CONCLUSION: The current literature provides clinical trial evidence that non-pharmacologic interventions can delay progression of functional impairment or disability among community-dwelling dementia patients. The clinical significance of this early evidence is uncertain. These early studies provide rationale for larger and longer-term studies to determine if these interventions are sufficiently potent to delay institutionalization.

Epigenetics of germ cells, stem cells, and early embryos.

The International Symposium entitled "Germ Cells, Epigenetics, Reprogramming, and Embryonic Stem Cells" was organized by Norio Nakatsuji (Kyoto University) and Hiromitsu Nakauchi (University of Tokyo) in Kyoto, Japan (November 15-18, 2005). The meeting provided an overview of this important research area and highlighted recent advances.

X chromosome activity in mouse XX primordial germ cells.

In the early epiblast of female mice, one of the two X chromosomes is randomly inactivated by a Xist-dependent mechanism, involving the recruitment of Ezh2-Eed and the subsequent trimethylation of histone 3 on lysine 27 (H3K27me3). We demonstrate that this random inactivation process applies also to the primordial germ cell (PGC) precursors, located in the proximal region of the epiblast. PGC specification occurs at about embryonic day (E)7.5, in the extraembryonic mesoderm, after which the germ cells enter the endoderm of the invaginating hindgut. As they migrate towards the site of the future gonads, the XX PGCs gradually lose the H3K27me3 accumulation on the silent X chromosome. However, using a GFP transgene inserted into the X chromosome, we observed that the XX gonadal environment (independently of the gender) is important for the substantial reactivation of the inactive X chromosome between E11.5 and E13.5, but is not required for X-chromosome reactivation during the derivation of pluripotent embryonic germ cells. We describe in detail one of the key events during female PGC development, the epigenetic reprogramming of the X chromosome, and demonstrate the role of the XX somatic genital ridge in this process.

Generation of primordial germ cells from pluripotent stem cells.

Embryonic stem (ES) cells, derived from pre-implantation embryo, embryonic germ (EG) cells, derived from embryonic precursors of gametes, primordial germ cells (PGCs), can differentiate into any cell type in the body. Moreover, ES cells have the capacity to differentiate into PGCs in vitro. In the present study we have shown the differentiation capacity of six EG cell lines to form PGCs in vitro, in comparison to ES cells. Cell lines were differentiated via embryoid body (EB) formation using the co-expression of mouse vasa homolog (Mvh) and Oct-4 to identify newly formed PGCs in vitro. We found an increase of PGC numbers in almost all analysed cell lines in 5-day-old EBs, thus suggesting that EG and ES cells have similar efficiency to generate PGCs. The addition of retinoic acid confirmed that the cultures had attained a PGC-like identity and continued to proliferate. Furthermore we have shown that the expression pattern of Prmt5 and H3K27me3 in newly formed PGCs is similar to that observed in embryonic day E11.5 PGCs in vivo. By co-culturing EBs with Chinese hamster ovary (CHO) cells some of the PGCs entered into meiosis, as judged by Scp3 expression. The derivation of germ cells from pluripotent stem cells in vitro could provide an invaluable model system to study both the genetic and epigenetic programming of germ cell development in vivo.

Heterogeneity in imprinted methylation patterns of pluripotent embryonic germ cells derived from pre-migratory mouse germ cells.

Pluripotent stem cells, termed embryonic germ (EG) cells, have been generated from both human and mouse primordial germ cells (PGCs). Like embryonic stem (ES) cells, EG cells have the potential to differentiate into all germ layer derivatives and may also be important for any future clinical applications. The development of PGCs in vivo is accompanied by major epigenetic changes including DNA demethylation and imprint erasure. We have investigated the DNA methylation pattern of several imprinted genes and repetitive elements in mouse EG cell lines before and after differentiation. Analysed cell lines were derived soon after PGC specification, "early", in comparison with EG cells derived after PGC colonisation of the genital ridge, "late" and embryonic stem (ES) cell lines, derived from the inner cell mass (ICM). Early EG cell lines showed strikingly heterogeneous DNA methylation patterns, in contrast to the uniformity of methylation pattern seen in somatic cells (control), late EG cell and ES cell lines. We also observed that all analysed XX cell lines exhibited less methylation than XY. We suggest that this heterogeneity may reflect the changes in DNA methylation taking place in the germ cell lineage soon after specification.

Human embryonic stem cell lines: socio-legal concerns and therapeutic promise.

Stem cell lines would be very valuable for the repair of diseased or damaged organs. Stem cells derived from adult tissues raise few ethical problems, and would not be rejected if derived from the patient. They show considerable plasticity and might be appropriate for some clinical conditions, but they tend not to grow well in culture. Stem cells derived from the early human embryo proliferate indefinitely in culture and can give rise to many different tissues, but their derivation requires destruction of the embryo, which is not ethically acceptable in some countries. Other countries allow strictly regulated destructive research on human embryos, usually those that have been produced for infertile couples in infertility clinics. Embryos that are no longer required for the couple's own reproductive project could be donated for research rather than just discarded. Different approaches are being developed to avoid immunological rejection of embryonic stem cells used for therapy. Derivation of embryonic stem cell lines by somatic cell nuclear transfer ('cloning') from the patients themselves might be one possible approach, but is unlikely to be used in routine clinical practice if more cost-effective methods are available.

A conversation with Dr Anne McLaren, DBE, DPhil, FRS, FRCOG.

Anne McLaren is one of the world's foremost developmental biologists; a leader in elucidating the principles of early mammalian development whose research has underpinned advances in reproductive medicine and the treatment of infertility. After undergraduate and postgraduate studies at Oxford University and postdoctoral work in London, she was for 15 years at the Institute of Animal Genetics in Edinburgh followed by 18 years as Director of the MRC Mammalian Development Unit in London. She is currently a Group Leader at the Wellcome Trust/Cancer Research UK Gurdon Institute in Cambridge. She was elected a Fellow of the Royal Society in 1975 and became the first woman to hold office in that Society - as Foreign Secretary, from 1991-1996. Dr McLaren played a pivotal role in the creation of the UK Human Fertilisation and Embryology Authority. She was a member of the Warnock Committee, served on the Voluntary (later Interim) Licensing Authority and was a key member of the HFEA from its establishment until the end of 2001. She chaired the Scientific and Technical Advisory Group of WHO's Human Reproduction Programme and is President of the Association of Women in Science and Engineering. She is a member of the European Group on Ethics that advises the European Commission on social and ethical implications of new technologies. In 2002, she was awarded (jointly with A. K. Tarkowski) the Japan Prize for Developmental Biology. She continues to have one of the sharpest minds in the business; for her, science has been not only a joy but an intellectual adventure of the highest order. She is interviewed here by Editorial Board Member Jane Denton.

Autism Spectrum Social Stories In Schools Trial (ASSSIST): study protocol for a feasibility randomised controlled trial analysing clinical and cost-effectiveness of Social Stories in mainstream schools.

INTRODUCTION: Current evidence suggests that Social Stories can be effective in tackling problem behaviours exhibited by children with autism spectrum disorder. Exploring the meaning of behaviour from a child's perspective allows stories to provide social information that is tailored to their needs. Case reports in children with autism have suggested that these stories can lead to a number of benefits including improvements in social interactions and choice making in educational settings. METHODS AND ANALYSIS: The feasibility of clinical and cost-effectiveness of a Social Stories toolkit will be assessed using a randomised control framework. Participants (n=50) will be randomised to either the Social Stories intervention or a comparator group where they will be read standard stories for an equivalent amount of time. Statistics will be calculated for recruitment rates, follow-up rates and attrition. Economic analysis will determine appropriate measures of generic health and resource use categories for cost-effectiveness analysis. Qualitative analysis will ascertain information on perceptions about the feasibility and acceptability of the intervention. ETHICS AND DISSEMINATION: National Health Service Ethics Approval (NHS; ref 11/YH/0340) for the trial protocol has been obtained along with NHS Research and Development permission from Leeds and York Partnership NHS Foundation Trust. All adverse events will be closely monitored, documented and reported to the study Data Monitoring Ethics Committee. At least one article in a peer reviewed journal will be published and research findings presented at relevant conferences. TRIAL REGISTRATION NUMBER: ISRCTN96286707.

A scientist's view of the ethics of human embryonic stem cell research.

Scientists are rarely immoral and seldom even amoral. The ethical principles that underlie much of their own work are shared with scientists in other countries to a much greater degree than the cultural and religious differences among those countries would lead one to expect. Like me, few will have had any formal training in bioethics; so how might life scientists approach the varied ethical issues that arise in human embryo and stem cell research?

Influence of sex chromosome constitution on the genomic imprinting of germ cells.

Germ cells in XY male mice establish site-specific methylation on imprinted genes during spermatogenesis, whereas germ cells in XX females establish their imprints in growing oocytes. We showed previously that in vitro, sex-specific methylation patterns of pluripotent stem cell lines derived from germ cells were influenced more by the sex chromosome constitution of the cells themselves than by the gender of the embryo from which they had been derived. To see whether the same situation would prevail in vivo, we have now determined the methylation status of H19 expressed from the maternal allele, and the expression and methylation status of a paternally expressed gene Peg3, in germ cells from sex-reversed and control embryos. For these imprinted genes, we conclude that the female imprint is a response of the germ cells to undergoing oogenesis, rather than to their XX chromosome constitution. Similarly, both our XY and our sex-reversed XX male germ cells clearly showed a male rather than a female pattern of DNA methylation; here, however, the sex chromosome constitution had a significant effect, with XX male germ cells less methylated than the XY controls.

The role of exogenous fibroblast growth factor-2 on the reprogramming of primordial germ cells into pluripotent stem cells.

The germ cell lineage is a specified cell population that passes through a series of differentiation steps before giving rise, eventually, to either eggs or sperm. We have investigated the manner in which primordial germ cells (PGCs) are reprogrammed in vitro to form pluripotent stem cells in response to exogenous fibroblast growth factor-2 (FGF-2). The response is dependent on time of exposure and concentration of FGF-2. PGCs isolated in culture show a motile phenotype and lose any expression of a characteristic germ cell marker, mouse vasa homolog. Subsequently, some but not all of the cells show further changes of phenotype, accompanied by changes in expression of endogenous FGF-2 and up-regulation of its receptor, fibroblast growth factor receptor-3, in the nucleus. We propose that it is from this reprogrammed component of the now heterogeneous PGC population that pluripotent stem cells arise.

How is the mouse germ-cell lineage established?

Six cells have been detected in the early mouse embryo that express the transcriptional repressor Blimp1--as also do all the 40 or so cells that constitute the founder germ cell pool a day later. Are these half-dozen cells the ancestors of the entire mouse germ cell lineage?

Identification and characterisation of mRif1: a mouse telomere-associated protein highly expressed in germ cells and embryo-derived pluripotent stem cells.

We have identified a mouse ortholog of the yeast Rif1 family of telomere-associated proteins on the basis of its high expression in primordial germ cells and embryo-derived pluripotent stem cell lines. mRif1 is also highly expressed in totipotent and pluripotent cells during early mouse development, and in male and female germ cells in adult mice. mRif1 expression is induced during derivation of embryonic stem cells and is rapidly down-regulated upon differentiation of embryonic stem cells in vitro. Furthermore, we show that mRif1 physically interacts with the telomere-associated protein mTrf2 and can be cross-linked to telomeric repeat DNA in mouse embryonic stem cells. mRif1 may be involved in the maintenance of telomere length or pluripotency in the germline and during early mouse development.

Sexually dimorphic development of mouse primordial germ cells: switching from oogenesis to spermatogenesis.

During embryogenesis, primordial germ cells (PGCs) have the potential to enter either spermatogenesis or oogenesis. In a female genital ridge, or in a non-gonadal environment, PGCs develop as meiotic oocytes. However, male gonadal somatic cells inhibit PGCs from entering meiosis and direct them to a spermatogenic fate. We have examined the ability of PGCs from male and female embryos to respond to the masculinising environment of the male genital ridge, defining a temporal window during which PGCs retain a bipotential fate. To help understand how PGCs respond to the male gonadal environment, we have identified molecular differences between male PGCs that are committed to spermatogenesis and bipotential female PGCs. Our results suggest that one way in which PGCs respond to this masculinising environment is to synthesise prostaglandin D(2). We show that this signalling molecule can partially masculinise female embryonic gonads in culture, probably by inducing female supporting cells to differentiate into Sertoli cells. In the developing testis, prostaglandin D(2) may act as a paracrine factor to induce Sertoli cell differentiation. Thus part of the response of PGCs to the male gonadal environment is to generate a masculinising feedback loop to ensure male differentiation of the surrounding gonadal somatic cells.

Analysis of sex differences in EGC imprinting.

Sex-specific differences are apparent in the methylation patterns of H19 and Igf2 imprinted genes in embryonic germ cells (EGCs) derived from 11.5 or 12.5 days post coitum (dpc) primordial germ cells (PGCs). Here we studied whether these differences are associated either with the sex chromosome constitution of the EGCs or with the sex of the genital ridge (testis versus ovary) from which the PGCs were isolated. For this purpose we derived pluripotent EGC lines from sex-reversed embryos, either XY embryos deleted for Sry (XY(Tdym1)) or XX embryos carrying an Sry transgene. Southern blotting of the EGC DNA was used to analyze the differentially methylated regions of Igf2 and H19. The analysis revealed that both genes were more methylated in EGCs with an XY sex chromosome constitution than in those with an XX sex chromosome constitution, irrespective of the phenotypic sex of the genital ridge from which the EGCs had been derived. We conclude that the sex-specific methylation is intrinsic and cell-autonomous, and is not due to any influence of the genital ridge somatic cells upon the PGCs.

Developmental fate of embryonic germ cells (EGCs), in vivo and in vitro.

Embryonic germ cells (EGCs) derived from mouse primordial germ cells (PGCs) are known both to colonize all cell lineages of the fetus and to make tumors in vivo. When aggregated with eight-cell embryos, EGCs from a new EGC line expressing green fluorescent protein (GFP) were found to contribute preferentially to the epiblast but unexpectedly were also capable of colonizing primary endoderm. When injected under the kidney capsule, EGCs derived from 12.5 days post coitum (dpc) PGCs formed differentiated tumors. The ability of EGCs to differentiate in an organ culture system depends upon their partners in cell culture. When EGCs, marked with a LacZ transgene, were mixed with disaggregated and reaggregated mouse fetal lung in an organ culture system, they remained undifferentiated. In urogenital ridge reaggregates on the other hand, some EGCs were capable of differentiating to form small epithelial cysts.

Xist expression and macroH2A1.2 localisation in mouse primordial and pluripotent embryonic germ cells.

The molecular mechanism underlying X chromosome inactivation in female mammals involves the non-coding RNAs Xist and its antisense partner Tsix. Prior to X inactivation, these RNAs are transcribed in an unstable form from all X chromosomes, both in the early embryo and in undifferentiated embryonic stem (ES) cells. Upon differentiation, the expression of these unstable transcripts from all alleles is silenced, and Xist RNA becomes stabilised specifically on the inactivating X chromosome. This pattern of expression is then maintained throughout subsequent somatic cell divisions. Once established, the inactive state of the X chromosome is remarkably stable, the only natural case of reactivation occurring in XX primordial germ cells (PGCs) when they enter the genital ridge. To gain insight into the X reactivation process, we have analysed Xist gene expression using RNA FISH in PGCs and also in PGC-derived embryonic germ (EG) cells. XX EG cells were shown to express unstable Xist/Tsix from both X chromosomes. In contrast, no unstable Xist/Tsix transcripts were detected in XX PGCs at any stage. Instead, a proportion of XX PGCs isolated from the genital ridge between 11.5 and 13.5 dpc (the period during which X chromosome reactivation occurs) showed an accumulation of stable Xist RNA on one X. The number of these cells decreased progressively and was nearly extinguished by 13.5 dpc. As a late marker for the inactive state, we analysed localisation of the histone H2A variant macroH2A1.2. Although macroH2A1.2 expression was observed in PGCs, no significant localisation to the inactive X was detected at any stage. We discuss these results in the context of understanding X chromosome reactivation.