72 research outputs found
Human blastocyst biopsy and vitrification
No full textBlastocyst biopsy is performed to obtain a reliable genetic diagnosis during IVF cycles with preimplantation genetic testing. Then, the ideal workflow entails a safe and efficient vitrification protocol, due to the turnaround time of the diagnostic techniques and to transfer the selected embryo(s) on a physiological endometrium in a following natural cycle. A biopsy approach encompassing the sequential opening of the zona pellucida and retrieval of 5-10 trophectoderm cells (ideally 7-8) limits both the number of manipulations required and the exposure of the embryo to sub-optimal environmental conditions. After proper training, the technique was reproducible across different operators in terms of timing of biopsy (~8 min, ranging 3-22 min based on the number of embryos to biopsy per dish), conclusive diagnoses obtained (~97.5%) and live birth rates after vitrified-warmed euploid blastocyst transfer (>40%). The survival rate after biopsy, vitrification and warming was as high as 99.8%. The re-expansion rate at 1.5 h from warming was as high as 97%, largely dependent on the timing between biopsy and vitrification (ideally ≤30 min), blastocyst morphological quality and day of biopsy. In general, it is better to vitrify a collapsed blastocyst; therefore, in non-PGT cycles, laser-assisted artificial shrinkage might be performed to induce embryo collapse prior to cryopreservation. The most promising future perspective is the non-invasive analysis of the IVF culture media after blastocyst culture as a putative source of embryonic DNA. However, this potential avant-garde is still under investigation and a reliable protocol yet needs to be defined and validated
A modem approach to the management of candidates for assisted reproductive technology procedures
No full textThe use of ovarian reserve markers in IVF clinical practice: a national consensus
No full textOvarian reserve markers have been documented to perform very well in the clinical practice. While this is widely recognized, still now there is no consensus on how to use new biomarkers in the clinical practice. This study was conducted among Italian IVF centres using the Delphi technique, a validated consensus-building process. Briefly three consecutive questionnaires were developed for clinicians in charge of IVF centres. In the first rounds, participants were asked to rate the importance of a list of statements regarding the categorization of ovarian response and the diagnostic role of biomarkers. In round 3, participants were asked to rate their agreement and consensus on the list of statements derived from the first two rounds. There were 120 respondents. Consensus was achieved for many points: (a) poor ovarian response is predicted on the basis of the following: AMH < 1 ng/ml or AFC < 7, FSH ≥ 10 IU/l, age ≥ 40 yrs; (b) hyper-response is predicted on the basis of the following: AMH > 3 ng/ml or AFC > 14; (c) day 3 FSH measurement should always be associated to estradiol; (d) AMH can be measured on a random basis; (e) the measurement of the AFC with the 2D technology may be considered adequate and (f) the AFC should be measured in the early follicular phase and consists in the total number of 2-9 mm follicles in both the ovaries. The present study suggests that extensive consensus on the importance and use of new ovarian reserve markers to improve IVF safety and performance is already present among clinicians
How should the best human embryo in vitro be? Current and future challenges for embryo selection
No full textDouble stimulation in the same ovarian cycle (DuoStim) is an intriguing strategy to improve oocyte yield and the number of competent embryos in a short timeframe
No full text: Proper ovarian stimulation regimens are crucial for any patient undergoing in-vitro fertilization (IVF). However, maximizing the oocyte yield in advanced maternal age patients with poor or suboptimal response is still a challenge. In fact, no standard treatment has been outlined yet to manage these women. Across the last years, an improved efficiency of the IVF units via blastocyst culture, vitrification and reliable embryo selection approaches paved the way to the investigation of novel unconventional stimulation protocols, like double stimulation in a single ovarian cycle (DuoStim). DuoStim, by conjugating follicular phase stimulation (FPS) and luteal phase stimulation (LPS) in the same ovarian cycle, allows to maximize the number of oocytes obtained in a short timeframe, a precious outcome when we aim at shortening time to pregnancy. In this regard, LPS seems to contribute to conventional stimulation with more oocytes with a comparable competence as FPS, retrieved per ovarian cycle. Although any stimulation protocol which exploits anovulatory waves of follicular growth needs a thorough investigation, no evidence has been produced to question the safety of DuoStim, which to date represents the most intriguing strategy to treat poor prognosis in IVF
Influence of the dopant profile on the phase contrast images of reverse biased p-n junctions
No full textA brief history of oocyte cryopreservation: Arguments and facts
No full text: The term "cryopreservation" refers to the process of cooling cells and tissues and storing them at subzero temperatures in order to stop all biological activity and preserve their viability and physiological competences for future use. Cooling to subzero temperatures is not a physiological condition for human cells; this is probably due to the high content of water in the living matter, whose conversion to ice crystals may be associated with severe and irreversible damage. Among reproductive cells and tissues, metaphase II oocytes are notably vulnerable to cryopreservation, mainly because of their large size, low surface area to volume ratio, relatively high water content and presence of the meiotic spindle. As human biological systems lack efficient internal defense mechanisms against chilling injuries, it is of the utmost importance to supply adequate external support, in terms of cryoprotectant additives, appropriate cooling/warming rates, and suitable long-term storage. Over the years, scientists have proposed different cryopreservation strategies in the effort to achieve an optimized recipe ensuring cell survival and, at the same time, maintenance of the physiological functions and abilities necessary to continue life. However, despite the first success obtained in the 1980s with frozen oocytes, it was not until recently that notable improvements in the cryopreservation technique, thanks to the advent of vitrification, allowed a breakthrough of this fine procedure
THREE-DIMENSIONAL FIELD MODELS FOR REVERSE BIASED P-N JUNCTIONS.
No full textIn order to obtain reliable quantitative information on the electrostatic field associated with reverse-biased p-n junctions and on the distribution of dopants, the physics of the so-called ''dead layer'' and the influence of charged oxide layers are of paramount importance. To this purpose, experimental observations near the edge of a TEM sample can be useful. In these conditions, however, phase computations required to interpret the experimental results are very challenging as the problem is intrinsically three-dimensional. In order to cope with this problem, a mixed analytical-numerical approach is presented and discussed
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