Mohamed Youssry

Current aspects of blastocyst cryopreservation

Cryopreservation of human gametes and embryos has become an essential part of assisted reproduction. Successful cryopreservation of human blastocysts is increasingly relevant as extended in-vitro culture of human embryos becomes more common, permitting routine use of blastocyst transfer in IVF programmes. This reduces the number of embryos transferred, thereby reducing multiple pregnancies and maximizing cumulative pregnancy rates per oocyte retrieval. The superiority of blastocyst freezing over earlier stage freezing in terms of implantation per thawed embryo transferred improves overall expectations for the cryopreservation programme. Therefore, a reliable procedure for the cryopreservation of blastocysts is needed because, after transfer, only a small number of supernumerary blastocysts are likely to be available for cryopreservation. Since the early 1980s, two common techniques have been used in cryopreservation: the conventional slow cooling method and the more recent rapid procedure known as vitrification. Vitrification has become an attractive alternative to slow freezing, since it appears to result in significantly higher survival and pregnancy rates. The aim of this review is to focus on the cryopreservation of human blastocysts using slow and rapid protocols and to assess the impact of the crypreservation protocol used on the survival, implantation and pregnancy rates.

Non-aqueous carbon black suspensions for lithium-based redox flow batteries: rheology and simultaneous rheo-electrical behavior

We report on the rheological and electrical properties of non-aqueous carbon black (CB) suspensions at equilibrium and under steady shear flow. The smaller the primary particle size of carbon black is, the higher the magnitude of rheological parameters and the conductivity are. The electrical percolation threshold ranges seem to coincide with the strong gel rather than the weak gel rheological threshold ones. The simultaneous measurements of electrical properties under shear flow reveal the well-known breaking-and-reforming mechanism that characterises such complex fluids. The small shear rate breaks up the network into smaller agglomerates, which in turn transform into anisometric eroded ones at very high shear rates, recovering the network conductivity. The type of carbon black, its concentration range and the flow rate range are now precisely identified for optimizing the performance of a redox flow battery. A preliminary electrochemical study for a composite anolyte (CB/Li4Ti5O12) at different charge-discharge rates and thicknesses is shown.

DNA damage of human spermatozoa in assisted reproduction: origins, diagnosis, impacts and safety

Sperm DNA contributes half the offsprings genomic material and abnormal DNA can lead to derangements in the reproductive process. Normal sperm genetic material is required for successful fertilization, as well as for further embryo and fetal development that will result in a healthy child. Thus, the damage to sperm DNA is critical in assisted reproductive techniques which are increasingly used to treat infertile couples. There has been improving data about the effects of human sperm DNA damage or fragmentation. As well, increasing knowledge concerning the effects of DNA damage on embryo and fetal development has been attained. This review aims to summarize the present knowledge on the impact of human sperm cell DNA damage on male infertility and outcome in the context of safety.

Embryo cryopreservation: is vitrification ready to replace slow freezing?

Cryopreservation of human gametes, embryos and blastocysts has become an integral part of assisted reproduction. This approach may have several advantages for infertile patients. It provides an opportunity to limit the numbers of embryos transferred while supernumerary embryos will be used in subsequent treatment cycles, thereby increasing the cumulative pregnancy rate. Furthermore, the potential risk of hyperstimulation syndrome can be reduced. In addition, storage of embryos from a cycle allows the patient to space the timing of sibling pregnancies and improve their potential of achieving a pregnancy at an advanced maternal age. Therefore, a reliable procedure for the cryopreservation of supernumerary embryos is needed. Since the early 1980s, two common techniques have been used in cryopreservation: the conventional slow cooling method and the more recent rapid procedure, known as vitrification. The latter needs a much higher concentration of cryoprotectants and faster cooling rates. Vitrification is qu...

The Impact of Third Trimester Maternal Serum Vitamin B12 and Folate Status on Fetal Birth Weight. Is Maternal Serum Homocysteine a Predictor of Low Birth Weight Infants

Objective: The aim of this study is to evaluate vitamin B12, folate, and homocysteine status in pregnant women in the third trimester of pregnancy and their relationship to fetal birth weight and their correlation to corresponding neonatal cord blood levels, and in addition, to evaluate the possibility of maternal serum homocysteine level as a predictor of low birth weight infants. Subjects and Methods: In this cross-sectional study, a total of two hundred pregnant women in third trimester (≥28 weeks) were recruited. After a detailed obstetrical and medical history, and clinical assessment, participants were subdivided into two groups: Group (A)—pregnant women who delivered average birth weight (ABW) infants and Group (B) for those who delivered low birth weight (LBW) infants between completed 37 and 42 weeks. Results: Vitamin B12 deficiency was observed in 24.1% of the total cohort. The mean vitamin B12 level was significantly lower in group (B) compared to group (A) (195.2 ± 38.9 vs. 225.9 ± 66.59 respectively P = 0.008). The mean level of homocysteine for women in group (B) was significantly higher than those determined from women in group (A) (9.10 ± 5.9 vs. 7.6 ± 3.83 respectively, P = 0.042). On the other hand, the mean folate levels showed statistically insignificant differences between both groups. The mean cord vitamin B12 level was significantly lower in LBW infants in comparison to ABW infants (277 ± 61.93 vs. 312.03 ± 81.87 respectively, P = 0.015), while the mean level of cord homocysteine for LBW infants was significantly higher than those levels determined from ABW infants (7.9 ± 3.79 vs. 6.6 ± 2.09 respectively P = 0.0049). Conclusion: Maternal micronutrients particularly cobalamin deficiency could be significant risk for LBW infants. Hyperhomocysteinemia has been shown to be a predictor for adverse pregnancy outcomes particularly LBW.

A live birth after transfer of a day 2 embryo derived from frozen-thawed zygotes that had undergone polar body biopsy: a case report

OBJECTIVE To present a live birth after freezing and thawing of biopsied oocytes. DESIGN Case report. SETTING Artificial reproduction unit of a university hospital. PATIENT(S) A primary infertile couple with asthenoteratozoospermia and repeated failures of intracytoplasmic sperm injection (ICSI). INTERVENTION(S) Screening of aneuploidy during the fourth ICSI cycle with polar body biopsy (PB) for repeated failures of artificial reproductive techniques and a transfer of a cryopreserved day 2 embryo derived from cryopreserved zygotes with slow-rate freezing after PB. MAIN OUTCOMES MEASURE(S) Live birth, viability, and survival. RESULT(S) A successful pregnancy and a live birth were presented after a transfer of day 2 embryos derived from oocytes that underwent PB and subsequent cryopreservation. CONCLUSION(S) Pregnancy can be obtained subsequent to cryopreservation and thawing after PB.