Effect of cryoprotectants on sperm vitrification
Robert Hofstra, Noriyuki Koibuchi, Suthat Fucharoen in Advances in Biomolecular Medicine, 2017
Vitrification is known to establish a glass-like solid state during the cooling process. It also has an economic advantage compared with the slow freezing method such as a lack of ice crystal formation due to an increase in the speed of temperature conduction, which provides a significant increase in cooling rates. This rapid cooling process circumvents the ice crystalline formation phase by converting solutions or water into a glass-like amorphous solid (Dinnyes et al., 2007). Vitrification conditions can be achieved by using high concentrations of cryoprotectants. The high concentration of cryoprotectants and extremely rapid rates of cooling are responsible for the formation of the solid state, thereby preventing the formation of intracellular ice crystals. One of the disadvantages of using high concentrations of cryoprotectants for sperm vitrification is the cytotoxic effect (Özkavukcu and Erdemli, 2002), which affects sperm recovery rates after the vitrification process. Therefore, it is particularly detrimental to patients who have low counts of sperm.
Radiation protection in the nuclear industry
Alan Martin, Sam Harbison, Karen Beach, Peter Cole in An Introduction to Radiation Protection, 2018
Of the product streams, the uranium stream does not present any significant radiological problem but the plutonium stream demands extremely high standards of containment to prevent any leakage that could lead to a potentially severe contamination hazard. The high-level waste stream is routed initially into special storage tanks, where it remains for a few years until it is ready for vitrification. This is a process in which the waste is mixed with glass, turning it into a solid form and reducing its volume to about one-third of its original amount. Vitrification allows the material to be stored safely in a form that should be suitable for long-term storage or eventual permanent disposal. In addition to the highly active waste streams, there are a number of subsidiary streams, the treatments of which depend on local conditions. The management of radioactive waste is covered in Chapter 14.
Preserving fertility
David J Cahill in Practical Patient Management in Reproductive Medicine, 2019
Women and men with various medical conditions can preserve their fertility if fertility is threatened by treatment of that condition. My first encounter with this issue was meeting young women presenting with early stages of breast cancer in their late 20s and early 30s. They faced the possibility that chemotherapy could destroy their follicles, wiping out any chance of having children should they survive the cancer. I have been involved with fertility preservation efforts in cases like this ever since. I have also obtained sperm from men who were unable to ejaculate because of different conditions – paraplegia, multiple sclerosis and neuropathies. Preserving the future fertility prospects of young teenagers tends to fall under the responsibility of paediatric gynaecologists and adolescent paediatricians. The technology of freezing and storing gametes and embryos is improving rapidly, and the last 10 years have seen a significant step forward with vitrification, a new rapid freezing technique. Now there are credible prospects for being able to offer most women and men a realistic opportunity to preserve fertility if they need to.
Spray freeze-drying for inhalation application: process and formulation variables
Published in Pharmaceutical Development and Technology, 2022
Mostafa Rostamnezhad, Hossein Jafari, Farzad Moradikhah, Sara Bahrainian, Homa Faghihi, Reza Khalvati, Reza Bafkary, Alireza Vatanara
Vitrification is a process that material enters a glassy state and prevents crystallization. The formation of ice crystals was allowed by regular freezing rate due to the slow freezing process. In contrast, during the fast freezing process, the temperature quickly dropped below the Tg and avoided the formation of the ice crystals. Consequently, fewer ice crystals formed, but the crystals were very fine. As a result, SEM images showed significant differences between particles formed by SFV/L and SFL methods. The particles produced by SFL were more spherical and smaller (50 nm) but, the SFV/L particles exhibited an open-cell structure. The structures formed in liquid nitrogen and isopentane were identical. Also, using suitable excipients such as sugars makes it possible to form an amorphous matrix and increase the Tg (Engstrom et al. 2007).
Perinatal outcome in children born after assisted reproductive technologies
Published in Upsala Journal of Medical Sciences, 2020
Ulla-Britt Wennerholm, Christina Bergh
Vitrification is an ultrarapid cryopreservation method, which instead of slow freezing has become the dominant method for cryopreservation in recent years. It has been associated with higher post-thaw survival rates and higher clinical pregnancy rates when compared with slow freezing (41,42). However, the high concentrations of cryoprotectants used for vitrification have raised concerns about possible negative health effects for the children. When comparing vitrification and slow freezing of day-3 embryos (43) or blastocysts (44), similar outcomes were found. A Nordic study compared vitrified blastocyst transfers with slow freezing day-2–3 embryo transfer (45). Except for a higher risk of preterm birth in the vitrified blastocyst group (aOR 1.33, 95% CI 1.09–1.62), there were no other differences. The higher risk of preterm birth was considered to be related to extended culture.
Four consecutive minimal ovarian stimulation (TetraStim) is a feasible alternative to increase the number of oocytes and improve live birth rates in poor responders who do not accept oocyte donation
Published in Gynecological Endocrinology, 2021
Selmo Geber, Luiza P. Geber, Marcello Valle, Marcos Sampaio
Vitrification of oocytes is one of the most important advances in the recent history of fertility preservation mainly due to the high survival rates. The oocyte survival rate observed in our study (95%) was similar to the described in previous published for non-POR young patients [21–23]. So, it can be assumed that POR patients do not have a worse prognosis than the observed in normal responders for vitrification. Fertilization rate (82%) was similar to the observed with fresh oocytes after ICSI with non-male factor infertility diagnosis [24] and higher to the previously published with vitrified/warmed oocytes in POR and non-POR patients [9,22,23]. Cleavage rate observed in our study (79%) was in accordance to the described by Cobo et al. [9] in a group of POR patients submitted to accumulation of oocytes and by Rienzi et al. [23] for patients that received donated vitrified oocytes. This result allowed the availability of 3.3 embryos for transfer (range = 1–6), for each patient.