New Zealand has had a national school science curriculum for more than 80 years. In the past the evolution content of this document has varied, and has at times been strongly influenced by ...creationist lobby groups. The 'new' science curriculum, to be fully implemented in 2010, places much greater emphasis than before on understanding evolution, and also on teaching the nature of science. Interplay between the two can potentially improve student understanding of the culture and processes of science in general and evolutionary theory in particular. While the explicit use of the word 'evolution' highlights its significance, it is necessary to provide both resources and pedagogical guidelines to support teachers in dealing with this important topic. Author abstract
Neural crest cells (NCC) are multipotent progenitors that migrate extensively throughout the developing embryo and generate a diverse range of cell types. Vagal NCC migrate from the hindbrain into ...the foregut and from there along the gastrointestinal tract to form the enteric nervous system (ENS), the intrinsic innervation of the gut, and into the developing lung buds to form the intrinsic innervation of the lungs. The aim of this study was to determine the developmental potential of vagal NCC that had already colonised the gut or the lungs. We used transgenic chicken embryos that ubiquitously express green fluorescent protein (GFP) to permanently mark and fate-map vagal NCC using intraspecies grafting. This was combined with back-transplantation of gut and lung segments, containing GFP-positive NCC, into the vagal region of a second recipient embryo to determine, using immunohistochemical staining, whether gut or lung NCC are competent of re-colonising both these organs, or whether their fate is restricted. Chick(GFP)-chick intraspecies grafting efficiently labelled NCC within the gut and lung of chick embryos. When segments of embryonic day (E)5.5 pre-umbilical midgut containing GFP-positive NCC were back-transplanted into the vagal region of E1.5 host embryos, the GFP-positive NCC remigrated to colonise both the gut and lungs and differentiated into neurons in stereotypical locations. However, GFP-positive lung NCC did not remigrate when back-transplanted. Our studies suggest that gut NCC are not restricted to colonising only this organ, since upon back-transplantation GFP-positive gut NCC colonised both the gut and the lung.
Abstract
BACKGROUND
A time lapse system (TLS) is utilized in some fertility clinics with the aim of predicting embryo viability and chance of live birth during IVF. It has been hypothesized that ...aneuploid embryos display altered morphokinetics as a consequence of their abnormal chromosome complement. Since aneuploidy is one of the fundamental reasons for IVF failure and miscarriage, attention has focused on utilizing morphokinetics to develop models to non-invasively risk stratify embryos for ploidy status. This could avoid or reduce the costs associated with pre-implantation genetic testing for aneuploidy (PGT-A). Furthermore, TLS have provided an understanding of the true prevalence of other dysmorphisms. Hypothetically, the incorporation of morphological features into a model could act synergistically, improving a model’s discriminative ability to predict ploidy status.
OBJECTIVE AND RATIONALE
The aim of this systematic review and meta-analysis was to investigate associations between ploidy status and morphokinetic or morphological features commonly denoted on a TLS. This will determine the feasibility of a prediction model for euploidy and summarize the most useful prognostic markers to be included in model development.
SEARCH METHODS
Five separate searches were conducted in Medline, Embase, PubMed and Cinahl from inception to 1 July 2021. Search terms and word variants included, among others, PGT-A, ploidy, morphokinetics and time lapse, and the latter were successively substituted for the following morphological parameters: fragmentation, multinucleation, abnormal cleavage and contraction. Studies were limited to human studies.
OUTCOMES
Overall, 58 studies were included incorporating over 40 000 embryos. All except one study had a moderate risk of bias in at least one domain when assessed by the quality in prognostic studies tool. Ten morphokinetic variables were significantly delayed in aneuploid embryos. When excluding studies using less reliable genetic technologies, the most notable variables were: time to eight cells (t8, 1.13 h, 95% CI: 0.21–2.05; three studies; n = 742; I2 = 0%), t9 (2.27 h, 95% CI: 0.5–4.03; two studies; n = 671; I2 = 33%), time to formation of a full blastocyst (tB, 1.99 h, 95% CI 0.15-3.81; four studies; n = 1640; I2 = 76%) and time to expanded blastocyst (tEB, 2.35 h, 95% CI: 0.06–4.63; four studies; n = 1640; I2 = 83%). There is potentially some prognostic potential in the degree of fragmentation, multinucleation persisting to the four-cell stage and frequency of embryo contractions. Reverse cleavage was associated with euploidy in this meta-analysis; however, this article argues that these are likely spurious results requiring further investigation. There was no association with direct unequal cleavage in an embryo that progressed to a blastocyst, or with multinucleation assessed on Day 2 or at the two-cell stage. However, owing to heterogeneous results and poor-quality evidence, associations between these morphological components needs to be investigated further before conclusions can be reliably drawn.
WIDER IMPLICATIONS
This first systematic review and meta-analysis of morphological and morphokinetic associations with ploidy status demonstrates the most useful morphokinetic variables, namely t8, t9 and tEB to be included in future model development. There is considerable variability within aneuploid and euploid embryos making definitively classifying them impossible; however, it is feasible that embryos could be prioritized for biopsy. Furthermore, these results support the mechanism by which algorithms for live birth may have predictive ability, suggesting aneuploidy causes delayed cytokinesis. We highlight significant heterogeneity in our results secondary to local conditions and diverse patient populations, therefore calling for future models to be robustly developed and tested in-house. If successful, such a model would constitute a meaningful breakthrough when accessing PGT-A is unsuitable for couples.
Multislice Q2TIPS is a widely used pulsed arterial spin labeling (PASL) technique for efficient and accurate quantification of cerebral blood flow (CBF). Slices are typically acquired inferior to ...superior from a tagging plane. Superior slices show signal loss greater than the loss expected from blood
T
1 decay. In order to assess the reasons for this additional signal loss, three single-slice acquisition studies were compared to multislice acquisition (six slices) in healthy volunteers. In Study 1 (
n=8), the tagging plane was fixed in location, and the inversion time (
TI
2) was 1500 ms for each slice. For Study 2 (
n=12), the tagging plane was fixed as in Study 1; however,
TI
2 increased as slices were acquired further from the tagging plane. In Study 3 (
n=9), the tagging plane was kept adjacent to the imaging slice, and
TI
2 was 1500 ms for every slice. Gray matter (GM) and white matter (WM) signal-to-noise ratio (SNR) and CBF were measured per slice. GM SNR from single-slice acquisitions was significantly higher at slices 4–6 in Study 2 and at slices 2–6 in Study 3 compared to multislice acquisitions. Signal loss in distal slices of multislice acquisitions can be attributed to the destruction of tagged bolus in addition to blood
T
1 decay. If limited brain coverage is acceptable, perfusion images with greater SNR are achievable with limited slices and placement of the tagging region immediately adjacent to the site of interest.
Abstract This study determined whether morphokinetic variables between aneuploid and euploid embryos differ as a potential aid to select euploid embryos for transfer. Following insemination, ...EmbryoScope time-lapse images from 98 blastocysts were collected and analysed blinded to ploidy. The morphokinetic variables were retrospectively compared with ploidy, which was determined following trophectoderm biopsy and analysis by array comparative genomic hybridization or single-nucleotide polymorphic array. Multiple aneuploid embryos were delayed at the initiation of compaction ( tSC ; median 85.1 hours post insemination (hpi); P = 0.02) and the time to reach full blastocyst stage ( tB ; median 110.9 hpi, P = 0.01) compared with euploid embryos ( tSC median 79.7 hpi, tB median 105.9 hpi). Embryos having single or multiple aneuploidy (median 103.4 hpi, P = 0.004 and 101.9 hpi, P = 0.006, respectively) had delayed initiation of blastulation compared with euploid embryos (median 95.1 hpi). No significant differences were observed in first or second cell-cycle length, synchrony of the second or third cell cycles, duration of blastulation, multinucleation at the 2-cell stage and irregular division patterns between euploid and aneuploid embryos. This non-invasive model for ploidy classification may be used to avoid selecting embryos with high risk of aneuploidy while selecting those with reduced risk. Chromosome anomalies (aneuploidy) are prevalent in human embryos and result in either IVF failure, miscarriage or the birth of children with chromosome disorders. After IVF, it is imperative to try to detect aneuploid embryos in order to transfer an embryo with a normal chromosome copy number (euploid) to maximize the chances of a successful and healthy live birth. Currently, the only option is to biopsy a cell (or cells) from the embryo and analyse these using complex and expensive genetic technology. Novel uninterrupted culturing methods using the EmbryoScope now enables detailed observation of the each embryo via time-lapse photography during the whole culture period, for up to 6 days. This new technology has permitted us to observe the development of human embryos in detail after IVF, providing analysis of complex patterns of cell division and cell movement (morphokinetics). As far as is known for the first time, we have demonstrated differences between aneuploid and euploid embryos based on their morphokinetic patterns, whereby aneuploid embryos are significantly delayed in reaching the later stages of development, during days 4 and 5 in culture. We postulate that, by using the unique, non-invasive and specifically designed models or algorithms developed in this study, embryologists can make more informed choices on the most viable embryo to select for transfer and reduce the risk of selecting an aneuploid embryo.
Introduction
Bed and chair sensor alarms are commonly used for falls prevention in hospitals, despite questionable efficacy. Research analysing older adults' experiences of alarms is scarce, and ...adults with cognitive impairment are consistently excluded.
Aim
The aim of this study was to explore how older adults with cognitive impairment perceive and experience falls prevention alarms in hospital.
Method
A qualitative descriptive design investigated older adults' experiences of alarms in a Geriatric Evaluation and Management ward in Melbourne. Patients were included if they had been provided an alarm. Semi‐structured interviews were the primary method of data collection with two observation sessions and medical record analyses completed to enable triangulation of findings. Data were subjected to thematic analysis, and the Person‐Environment‐Occupation framework was chosen to add insight into the complexities of older adults' experiences of alarms.
Findings
All 11 participants had a level of cognitive impairment with delirium, confusion, or impulsiveness recorded in their medical file. Two overarching themes were identified: communication and collaboration with staff and rationalisation of alarm use. Participants' perceived staff were focussed on falls prevention but experienced a lack of communication about the purpose of alarms. Participants wanted an individualised approach to alarms. Some were comforted with the thought of alarms alerting staff, making them feel well cared for and believed alarms were a useful ‘back‐up’. Others found alarms uncomfortable, frustrating, and restricting. Application of the Person‐Environment‐Occupation framework provided insight into how enabling and restrictive factors can impact whether the alarm is experienced positively or negatively. Seven unwitnessed falls occurred during the participants' admissions. Thirty‐four per cent of alarm triggers observed were considered false alerts.
Conclusion
Older adults commonly reported negative experiences using bed/chair sensor alarms. Occupational therapists have the training to collaborate with people with cognitive impairment and assess the usefulness of alarms in reducing falls, based on how they interact with the older adult's unique person, environment, and occupation domains.
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