High maternal folic acid intake around conception alters mouse blastocyst lineage allocation and expression of key developmental regulatory genes.

Folate, a cofactor for the supply of one-carbon groups, is required by epigenetic processes to regulate cell lineage determination during development. The intake of folic acid (FA), the synthetic form of folate, has increased significantly over the past decade, but the effects of high periconceptional FA intake on cell lineage determination in the early embryo remains unknown. Here, we investigated the effect of maternal high FA (HFA) intake on blastocyst development and expression of key regulatory genes. C57BL/6 adult female mice were fed either Control diet (1 mg FA) for 4 weeks before conception and during the preimplantation period (Con-Con); Control diet for 4 weeks preconception, followed by HFA (5 mg FA) diet during preimplantation (Con-HFA); or HFA diet for 4 weeks preconception and during preimplantation (HFA-HFA). At E3.5, blastocyst cell number, protein, and mRNA expression were measured. In HFA-HFA blastocysts, trophectoderm cell numbers and expression of CDX2, Oct-4, and Nanog were reduced compared with Con-Con blastocysts; Con-HFA blastocysts showed lower CDX2 and Oct-4 expression than Con-Con blastocysts. These findings suggest periconceptional HFA intake induces changes in key regulators of embryo morphogenesis with potential implications for subsequent development.

A lateral dynamics of a wheelchair: identification and analysis of tire parameters.

In vehicle dynamics studies, the tire behaviour plays an important role in planar motion of the vehicle. Therefore, a correct representation of tire is a necessity. This paper describes a mathematical model for wheelchair tire based on the Magic Formula model. This model is widely used to represent forces and moments between the tire and the ground; however some experimental parameters must be determined. The purpose of this work is to identify the tire parameters for the wheelchair tire model, implementing them in a dynamic model of the wheelchair. For this, we developed an experimental test rig to measure the tires parameters for the lateral dynamics of a wheelchair. This dynamic model was made using a multi-body software and the wheelchair behaviour was analysed and discussed according to the tire parameters. The result of this work is one step further towards the understanding of wheelchair dynamics.

Measurement of wheelchair contact force with a low cost bench test.

In mechanical engineering, it is well established that contact between the tire and the ground is a key parameter in characterizing the dynamic behavior of vehicles and an important factor in design control. Therefore, it is an important part of dynamic simulation models for vehicles, including wheelchairs. This work presents a bench test designed to experimentally monitor and measure the forces transmitted to the ground by a moving wheel. The test bench is composed of a table and a track with a fixed wheel structure and powertrain system. The table is an integrated structure that measures the longitudinal and lateral forces produced by tire contact. This table allows characterization of the tire and tests the tire under varying loads at different slip and camber angles. Additionally, the test bench can also be used to evaluate other tires, such as caster tires. The performances of the new device are illustrated, and the results show the differences between tires, which are related to the dynamic behaviors of wheelchair model. Finally, preliminary experiments performed using the test bench have shown that it is able to monitor and measure the forces generated by the contact between the tire and the ground.

Embryos, DOHaD and David Barker.

The early embryo and periconceptional period is a window during which environmental factors may cause permanent change in the pattern and characteristics of development leading to risk of adult onset disease. This has now been demonstrated across small and large animal models and also in the human. Most evidence of periconceptional 'programming' has emerged from maternal nutritional models but also other in vivo and in vitro conditions including assisted reproductive treatments, show consistent outcomes. This short review first reports on the range of environmental in vivo and in vitro periconceptional models and resulting long-term outcomes. Second, it uses the rodent maternal low protein diet model restricted to the preimplantation period and considers the stepwise maternal-embryonic dialogue that comprises the induction of programming. This dialogue leads to cellular and epigenetic responses by the embryo, mainly identified in the extra-embryonic cell lineages, and underpins an apparently permanent change in the growth trajectory during pregnancy and associates with increased cardiometabolic and behavioural disease in adulthood. We recognize the important advice of David Barker some years ago to investigate the sensitivity of the early embryo to developmental programming, an insight for which we are grateful.

Nutrition of females during the peri-conceptional period and effects on foetal programming and health of offspring.

The period around the time of conception is one characterised by considerable cytological and molecular restructuring as ovulation occurs, the oocyte is fertilised and the embryonic developmental programme begins. The intrinsic processes regulating peri-conceptional progression are supplemented by environmental factors, which contribute important metabolic information that influences several aspects of the developmental programme. Indeed, there is growing evidence from different mammalian animal models, reviewed here, that the peri-conceptional environment mediated through maternal nutrition can modify development throughout gestation and affect the physiological and metabolic health of adult offspring. The concept that adult disease risk may owe its origin to the quality of peri-conceptional maternal nutrition is one, which merits further research for mechanistic understanding and devising preventive strategies.

Use of a lacZ fusion to study transcriptional regulation of the Rhodobacter capsulatus hemA gene.

An EcoRI fragment containing the Rhodobacter capsulatus hemA promoter has been cloned into a lacZ translational fusion vector. The resulting plasmid produced a hemA-lacZ fusion protein with a molecular mass of 147,000. Expression of the hemA-lacZ fusion, as measured by production of beta-galactosidase, was regulated 2- to 3-fold by oxygen tension. The unexpectedly small change in beta-galactosidase levels suggests that transcriptional regulation of the hemA gene is not the major factor in oxygen-mediated control of porphyrin synthesis.