Failure of homologous synapsis and sex-specific reproduction problems

The prophase of meiosis I ensures the correct segregation of chromosomes to each daughter cell. This includes the pairing, synapsis, and recombination of homologous chromosomes. A subset of chromosomal abnormalities, including translocation and inversion, disturbs these processes, resulting in the failure to complete synapsis. This activates the meiotic pachytene checkpoint, and the gametes are fated to undergo cell cycle arrest and subsequent apoptosis. Spermatogenic cells appear to be more vulnerable to the pachytene checkpoint, and male carriers of chromosomal abnormalities are more susceptible to infertility. In contrast, oocytes tend to bypass the checkpoint and instead generate other problems, such as chromosome imbalance that often leads to recurrent pregnancy loss in female carriers. Recent advances in genetic manipulation technologies have increased our knowledge about the pachytene checkpoint and surveillance systems that detect chromosomal synapsis. This review focuses on the consequences of synapsis failure in humans and provides an overview of the mechanisms involved. We also discuss the sexual dimorphism of the involved pathways that leads to the differences in reproductive outcomes between males and females

Evaluation of Explanted CorMatrix Intracardiac Patches in Children With Congenital Heart Disease

Animal data demonstrate that intracardiac patches of decellularized porcine small intestine submucosa (CorMatrix; CorMatrix Cardiovascular, Inc, Atlanta, GA) become repopulated with native cells, suggesting the possibility of a substrate for regenerative tissue in humans. We report the only prospective series to date of explanted CorMatrix patches placed in infants with congenital heart disease

Pediatric Giant Right Atrial Aneurysm: A Case Series and Review of the Literature

Giant right atrial aneurysm is a rare form of congenital heart disease with a wide spectrum of clinical presentation varying from asymptomatic patients to those with refractory atrial arrhythmias or severe airway obstruction. Diagnosis is often confused with other causes of right atrial dilation such as E bstein disease. Because of its rare occurrence and variable clinical presentation, inconsistencies in medical and surgical management strategies exist between centers. We present five cases of giant right atrial aneurysm managed at our institution and discuss the clinical presentation, diagnostic challenges, and medical and surgical management.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/107528/1/chd12079.pd

Long-segment thoracoabdominal aortic occlusions in childhood

Developmental coarctation, hypoplasia, and occlusion of the abdominal aorta is a rare disease encompassing many differing etiologies and diverse methods of treatment. Long-segment thoracoabdominal aortic occlusion, an extreme manifestation of this disorder, has not previously been reported in children. Two pediatric patients with this entity, a 5- and 13-year-old with uncontrolled hypertension, underwent extensive arterial reconstructions for this entity and provided the impetus for this report. An ascending thoracic aorta to infrarenal aortic expanded polytetrafluoroethylene bypass was undertaken in the younger child. A distal thoracic aorto-bi-iliac artery expanded polytetrafluoroethylene bypass, with implantation of the left renal artery to one graft limb and a right renal artery bypass originating from the other limb, was performed in the older child. There were no major perioperative complications. Both patients were discharged with easily controlled blood pressures. They have remained normotensive at 13 and 14 months follow-up

Cruciform extrusion propensity of human translocation-mediating palindromic AT-rich repeats

There is an emerging consensus that secondary structures of DNA have the potential for genomic instability. Palindromic AT-rich repeats (PATRRs) are a characteristic sequence identified at each breakpoint of the recurrent constitutional t(11;22) and t(17;22) translocations in humans, named PATRR22 (∼600 bp), PATRR11 (∼450 bp) and PATRR17 (∼190 bp). The secondary structure-forming propensity in vitro and the instability in vivo have been experimentally evaluated for various PATRRs that differ regarding their size and symmetry. At physiological ionic strength, a cruciform structure is most frequently observed for the symmetric PATRR22, less often for the symmetric PATRR11, but not for the other PATRRs. In wild-type E. coli, only these two PATRRs undergo extensive instability, consistent with the relatively high incidence of the t(11;22) in humans. The resultant deletions are putatively mediated by central cleavage by the structure-specific endonuclease SbcCD, indicating the possibility of a cruciform conformation in vivo. Insertion of a short spacer at the centre of the PATRR22 greatly reduces both its cruciform extrusion in vitro and instability in vivo. Taken together, cruciform extrusion propensity depends on the length and central symmetry of the PATRR, and is likely to determine the instability that leads to recurrent translocations in humans

Association of Digoxin With Interstage Mortality: Results From the Pediatric Heart Network Single Ventricle Reconstruction Trial Public Use Dataset

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139107/1/jah31279.pd