Kenneth I. Aston

Learn More
Twin birth rates have increased markedly in developed countries since the 1970s for two primary reasons: increasing maternal age and the advent and increasing use of fertility treatments. In addition, monozygotic (MZ) twin pregnancies have been reported to occur at a significantly higher rate following assisted reproductive technologies (ART) procedures(More)
Telomere length (TL) dynamics in vivo are defined by TL and its age-dependent change, brought about by cell replication. Leukocyte TL (LTL), which reflects TL in hematopoietic stem cells (HSCs), becomes shorter with age. In contrast, sperm TL, which reflects TL in the male germ cells, becomes longer with age. Moreover, offspring of older fathers display(More)
BACKGROUND In spite of tremendous efforts by a number of groups, the search for single nucleotide polymorphisms (SNPs) strongly associated with male factor infertility by means of gene re-sequencing studies has yielded few likely candidates. A recent pilot, genome-wide SNP association study (GWAS) identified a list of SNPs associated with oligozoospermia(More)
OBJECTIVE To evaluate genome-wide DNA methylation patterns in sperm from men with abnormal sperm chromatin packaging and patients displaying abnormal embryogenesis after IVF in the absence of known female factors. DESIGN Case-control study. SETTING University andrology and research laboratory. PATIENT(S) Men with abnormally high and low protamine(More)
Based on microarray data comparing gene expression of fibroblast donor cells and bovine somatic cell nuclear transfer (SCNT) and in vivo produced (AI) blastocysts, a group of genes including several transcription factors was selected for evaluation of transcript abundance. Using SYBR green-based real-time polymerase chain reaction (Q-PCR) the levels of POU(More)
The effects of bovine cumulus cell-conditioned medium on cloned bovine embryonic development and subsequent chromosome complement were examined using an air-dry procedure. Conditioned media were prepared using CR1aa supplemented with either fetal bovine serum (FBS) or bovine serum albumin (BSA). Nuclear-transferred embryos were reconstructed with nuclei(More)
This study indicated that prolonged exposure of donor cell nuclei to oocyte cytoplasm before activation results in abnormal chromatin morphology, and reduced development to compacted morula/blastocyst stage in vitro. However, after transfer of embryos to recipients, there was no difference in pregnancy rates throughout gestation. Chromatin morphology was(More)
The putative effect of nicotine on maturation and the chromosomal complement of bovine oocytes were investigated in the present study. Cumulus-enclosed oocytes were incubated in maturation medium with 0, 0.5, 1.0, 2.5, 5.0, and 10.0 mmol concentrations of nicotine. The results indicated that: (1) nicotine affected cumulus cell expansion in a dose-dependent(More)
Gonadal failure, along with early pregnancy loss and perinatal death, may be an important filter that limits the propagation of harmful mutations in the human population. We hypothesized that men with spermatogenic impairment, a disease with unknown genetic architecture and a common cause of male infertility, are enriched for rare deleterious mutations(More)