In this task, you are given an abstract of article. Your task is to generate title for this article. Preferred titles are under thirty words.

Input: Consider Input: The mammalian A-type cyclin family consists of two members, cyclin A1 (encoded by Ccna1) and cyclin A2 (encoded by Ccna2). Cyclin A2 promotes both G1/S and G2/M transitions, and targeted deletion of Ccna2 in mouse is embryonic lethal. Cyclin A1 is expressed in mice exclusively in the germ cell lineage and is expressed in humans at highest levels in the testis and certain myeloid leukaemia cells. To investigate the role of cyclin A1 and possible redundancy among the cyclins in vivo, we generated mice bearing a null mutation of Ccna1. Ccna1-/- males were sterile due to a block of spermatogenesis before the first meiotic division, whereas females were normal. Meiosis arrest in Ccna1/ males was associated with increased germ cell apoptosis, desynapsis abnormalities and reduction of Cdc2 kinase activation at the end of meiotic prophase. Cyclin A1 is therefore essential for spermatocyte passage into the first meiotic division in male mice, a function that cannot be complemented by the concurrently expressed B-type cyclins.

Output: Cyclin A1 is required for meiosis in the male mouse

Input: Consider Input: AIMS Recent evidence suggests that cardiac progenitor cells (CPCs) may improve cardiac function after injury. The underlying mechanisms are indirect, but their mediators remain unidentified. Exosomes and other secreted membrane vesicles, hereafter collectively referred to as extracellular vesicles (EVs), act as paracrine signalling mediators. Here, we report that EVs secreted by human CPCs are crucial cardioprotective agents.
METHODS AND RESULTS CPCs were derived from atrial appendage explants from patients who underwent heart valve surgery. CPC-conditioned medium (CM) inhibited apoptosis in mouse HL-1 cardiomyocytic cells, while enhancing tube formation in human umbilical vein endothelial cells. These effects were abrogated by depleting CM of EVs. They were reproduced by EVs secreted by CPCs, but not by those secreted by human dermal fibroblasts. Transmission electron microscopy and nanoparticle tracking analysis showed most EVs to be 30-90 nm in diameter, the size of exosomes, although smaller and larger vesicles were also present. MicroRNAs most highly enriched in EVs secreted by CPCs compared with fibroblasts included miR-210, miR-132, and miR-146a-3p. miR-210 down-regulated its known targets, ephrin A3 and PTP1b, inhibiting apoptosis in cardiomyocytic cells. miR-132 down-regulated its target, RasGAP-p120, enhancing tube formation in endothelial cells. Infarcted hearts injected with EVs from CPCs, but not from fibroblasts, exhibited less cardiomyocyte apoptosis, enhanced angiogenesis, and improved LV ejection fraction (0.8 6.8 vs. -21.3 4.5%; P < 0.05) compared with those injected with control medium.
CONCLUSION EVs are the active component of the paracrine secretion by human CPCs. As a cell-free approach, EVs could circumvent many of the limitations of cell transplantation.

Output: Extracellular vesicles from human cardiac progenitor cells inhibit cardiomyocyte apoptosis and improve cardiac function after myocardial infarction.

Input: Consider Input: Independent mobility in early childhood has been associated with the development of various cognitive and psychosocial skills. However, children with physical disabilities are not always able to move independently and may be at risk for delays in these areas. Early provision of powered mobility can offer young children an opportunity for independent mobility. Despite this, there is little information to help determine when a young child has the cognitive skills necessary to operate a powered wheelchair safely. This current research aims to identify these skills. A cognitive assessment battery and a wheelchair mobility training and assessment program were developed. Twenty-six children with physical disabilities between the ages of 20 and 36 months were evaluated on the cognitive assessment and participated in the wheelchair training and assessment program. A stepwise regression analysis was used to determine which of the cognitive skills predicted wheelchair mobility performance. The cognitive domains of spatial relations and problem solving were found to be significant and accounted for 57% of the variance in wheelchair skills. Developmental cut-off points on these scales as they relate to wheelchair skills are presented and clinical applications are discussed.
Output: Cognitive predictors of young children's readiness for powered mobility.