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Biomedical subjects

Panayiotis M Zavos

Publications and source records attributed to Panayiotis M Zavos.

7 recordsLinked to original sources
PubMed2006

In vitro blastocyst development from serially split mouse embryos and future implications for human assisted reproductive technologies.

OBJECTIVE: To assess the efficacy of serial splitting of mouse embryos with respect to blastocyst development. DESIGN: Prospective study. SETTING: Commercial research facility. ANIMAL(S): Commercially available mouse embryos from B6C3F-1 x B6D2F-1. INTERVENTION(S): One, two, and three blastomeres were biopsied from two-, four-, and six-cell embryos, respectively, and were inserted into empty zona pellucida recipients (first split). These embryos were cultured to reach their original cell number status and then were split again (second split). Once these embryos regained their original cell status, they were split yet again (third split). MAIN OUTCOME MEASURE(S): Blastocyst development of embryos split serially at the two-, four-, and six-cell stages. RESULT(S): The blastocyst development rate for two-, four-, and six-cell embryos subjected to a first split was 74.3%, 75.0%, and 66.6%, respectively, as compared with 71.8%, 62.6%, and 48.4% (second split) and 48.4%, 38.1%, and 10.6% (third split). CONCLUSION(S): First and second splitting of cleavage-stage embryos has yielded high efficiency rates for blastocyst development when compared with the third splitting, which did not provide any beneficial advantage for further embryo splitting and multiplication. This is the first study reporting on three serial embryo splittings in a mammalian species. Embryo splitting may have significant impact and applications in human assisted reproductive technology.

Animals↗
PubMed2006

Stem cells and cellular therapy: potential treatment for cardiovascular diseases.

This paper reviews the current status of cloning and stem cell research and its application to treating various diseases, particularly cardiovascular disease. Recently new techniques have been developed to isolate embryonic stem cells from preimplantation embryos. These cells are undifferentiated and are therefore able to develop into the cells of whichever organ it is in contact with. These cells would be especially beneficial for the treatment of ischemia and various other cardiovascular diseases. There are a variety of various issues that need to be discussed before this technology can be applied safely, including government regulations to ensure the clinical safety and effectiveness of the procedures, as well as the prevention of improper handling or the use of contaminated tissues.

Cardiovascular Diseases↗
PubMed2006

Evaluation of the embryonic preimplantation potential of human adult somatic cells via an embryo interspecies bioassay using bovine oocytes.

OBJECTIVE: To examine the embryonic preimplantation potential of human adult somatic cells by creating interspecies embryos via somatic cell nuclear transfer (SCNT) using bovine oocytes. DESIGN: Prospective study. SETTING: Research facility of Reprogen. PATIENT(S): Infertile couples. INTERVENTION(S): Enucleated bovine oocytes were fused via SCNT with either human granulosa (HG) or fibroblast (HF) cells and cultured in vitro. Polymerase chain reaction (PCR) and DNA analysis were performed on the interspecies embryos. Parthenogenetically activated embryos served as controls. MAIN OUTCOME MEASURE(S): Embryonic preimplantation development after interspecies SCNT. RESULT(S): From enucleated bovine oocytes fused with HG cells (n = 48) and HF cells (n = 75), 15 HG- and 22 HF-derived embryos developed, some of which progressed to blastocysts (31.3% vs. 29.3%, respectively). The PCR and DNA analysis showed that the interspecies embryos contained human genomic DNA specific for the individual DNA profile of the HG or HF donor cells used for SCNT. In addition, both bovine- and human-specific mitochondrial DNA was detectable in the interspecies embryos up to the blastocyst stage. Parthenogenetic development was 46.8% and 64.9% for the HG and HF series, respectively. The SCNT efficiency index, defined as the ratio of SCNT and parthenogenetic success rate, was 66.8% for HG cells and 45.5% for HF cells. CONCLUSION(S): This interspecies bioassay can be utilized to determine and assess the embryonic preimplantation potential of different types of human adult somatic cells.

Animals↗
PubMed2006

Seminal characteristics and sexual behavior in men of different age groups: is there an aging effect?

AIM: To assess the seminal characteristics as well as the sexual behavior of men of various age groups to establish the presence of an aging effect on those characteristics. METHODS: Semen samples were collected from men (n = 792) undergoing in vitro fertilization or intrauterine insemination in cases of female factor infertility only. Samples were collected using a seminal collection device at intercourse and evaluated manually according to World Health Organization (WHO) standards. Men were divided into four groups according to their ages: (i) 20-30, (ii) 31-40, (iii) 41-50 and (iv) 51-60 years, and their seminal characteristics and responses to a sexual behavior questionnaire were compared. RESULTS: The data showed statistically significant differences in the seminal characteristics tested, most notably in the sperm concentration, motility, grade of motility, hypo-osmotic swelling and normal sperm morphology. Furthermore, the decline in normal sperm morphology with age was more pronounced when using strict criteria rather than WHO standards. There were also differences in total sperm count, total motile sperm and total functional sperm fraction (assessed by both WHO and strict criteria). Significant differences were also observed in the sexual behavior patterns in older men in terms of the number of years they have been trying to conceive, sexual frequency and sexual satisfaction. CONCLUSION: The data clearly illustrate an aging effect on semen characteristics and sexual behavior in men as they age. It is suggested that the aging effect be taken into consideration when proposing normal standard values for semen characteristics in routine semen analysis as outlined by WHO standards.

Adult↗