Publications by authors named "Llacer J"

Objective: To compare DuoStim versus a conventional approach in patients indicated to Preimplantation-Genetic-Testing for both monogenic conditions and aneuploidies (PGT-M + PGT-A).

Study Design: Retrospective case-control study. In 5 years, 132 couples indicated to PGT-M + PGT-A who obtained ≤5 blastocysts after a first retrieval were suggested to undergo a second stimulation in the same ovarian cycle.

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In eukaryotic translation initiation, the 48S preinitiation complex (PIC) scans the 5' untranslated region of mRNAs to search for the cognate start codon (AUG) with assistance from various eukaryotic initiation factors (eIFs). Cognate start codon recognition is precise, rejecting near-cognate codons with a single base difference. However, the structural basis of discrimination of near-cognate start codons was not known.

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Objective: To compare the oocyte yield between follicular-phase stimulation (FPS) and luteal-phase stimulation (LPS) in suboptimal responders.

Design: Prospective, randomized, crossover clinical trial.

Patients: Forty-one patients with infertility according to the POSEIDON (Patient-Oriented Strategies Encompassing IndividualizeD Oocyte Number) criteria (1b/2b).

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Article Synopsis
  • The study compared two protocols for ovarian stimulation in oocyte donors to evaluate the quantity of cumulus-oocyte complexes and mature oocytes (metaphase II).
  • The TAIL group received a single injection of corifollitropin alfa after a 7-day contraceptive break, while the control group followed a conventional protocol with additional rFSH from the 8th day.
  • Results showed that the TAIL group had significantly fewer cumulus-oocyte complexes and metaphase II oocytes, as well as a higher rate of failed oocyte retrieval compared to the control group.
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Article Synopsis
  • Endometrial receptivity is a key area of research in assisted reproduction, focusing on how to optimize the timing of embryo transfers.
  • Fertility clinics use tests that analyze gene expression to determine each woman's unique 'window of implantation' for personalized treatment.
  • Despite the growing interest, there’s still no clear consensus on the necessity of these tests for infertile couples or those with repeated implantation failures.
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Objective: To assess whether high body mass index (BMI) in either oocyte donors or recipients is associated with poorer outcomes after the first single blastocyst transfer.

Design: Retrospective study including 1,394 first blastocyst single embryo transfers (SETs) conducted by 1,394 recipients during oocyte donation cycles with the gametes retrieved from 1,394 women (January 2019-July 2021). Four BMI clusters were defined for both donors and recipients (underweight: <18.

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Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes COVID-19, by infecting cells via the interaction of its spike protein (S) with the primary cell receptor angiotensin-converting enzyme (ACE2). To search for inhibitors of this key step in viral infection, we screened an in-house library of multivalent tryptophan derivatives. Using VSV-S pseudoparticles, we identified compound as a potent entry inhibitor lacking cellular toxicity.

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Modifications in vaginal and endometrial microbiome and microbiota have been associated with fewer implantation rates and poorest pregnancy outcomes. Therefore, its study has emerged as a new biomarker in reproductive medicine. Despite the numerous papers published on probiotic use for vaginal dysbiosis and their actual wide empiric use especially for infertile patients, there is still no clear answer to justify their recommendation.

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Thrombophilia is a group of inherited or acquired coagulation disorders that have been associated with reproductive failure. However, there are still no clear recommendations on whether its inclusion in the initial study of the infertile couple or patients with recurrent implantation failure is necessary. In this discussion paper, based on a SWOT (strengths, weaknesses, opportunities, threats) analysis, the different aspects of the repercussions of thrombophilia screening and treatment in reproduction are evaluated.

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The S:A222V point mutation, within the G clade, was characteristic of the 20E (EU1) SARS-CoV-2 variant identified in Spain in early summer 2020. This mutation has since reappeared in the Delta subvariant AY.4.

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Research Question: Is embryo cryopreservation a cause of high birth weight and large for gestational age (LGA) in singletons resulting from vitrified-warmed embryo transfer?

Design: Retrospective cohort study evaluating 670 oocyte recipients who underwent fresh (367 cycles) or vitrified-warmed embryo transfer (303 cycles) at Instituto Bernabeu between July 2017 and March 2019. All single blastocyst transfers carried out in an artificial cycle that resulted in a singleton live birth were included.

Results: Maternal age (42.

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Twisted uterus is detected when the body of the uterus is rotated from the cervical canal. This anomaly may be due to different causes, such as uterine fibroids, endometriosis or the presence of both. The study has aimed to compare the effect of the twisted uterus cause in terms of reproductive treatment outcomes.

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The eukaryotic initiation factor 3 (eIF3) complex is involved in every step of translation initiation, but there is limited understanding of its molecular functions. Here, we present a single particle electron cryomicroscopy (cryo-EM) reconstruction of yeast 48S ribosomal preinitiation complex (PIC) in an open conformation conducive to scanning, with core subunit eIF3b bound on the 40S interface near the decoding center in contact with the ternary complex eIF2·GTP·initiator tRNA. eIF3b is relocated together with eIF3i from their solvent interface locations observed in other PIC structures, with eIF3i lacking 40S contacts.

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Uterine microbiota may be involved in reproductive health and disease. This study aims to describe and compare the vaginal and endometrial microbiome patterns between women who became pregnant and women who did not after in vitro fertilization. We also compared the vaginal and endometrial microbiome patterns between women with and without a history of repeated implantation failures (RIF).

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Objective: To compare the endometrial and vaginal microbiome of women with and without chronic endometritis.

Study Design: A cohort study with 60 patients undergoing assisted reproductive treatment with their own or donated gametes was undertaken. Vaginal and endometrial samples were taken in the cycle prior to embryo transfer.

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The aim of our study was to investigate the effect of maternal and embryo C677T and A1298C polymorphisms on embryo aneuploidies and mosaicism and the correlation between these genetic variants in transferred euploid embryos and IVF outcomes. genotype was analyzed in 77 women who performed an IVF/ICSI cycle with PGT-A. Moreover, to evaluate the effect of embryo polymorphisms on embryo aneuploidies and mosaicism, the genotype was analyzed in 191 biopsied embryos from the PGT-A cycles of these patients.

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Objective: To study uterine peristalsis using step-by-step 4-dimensional (4D) ultrasound assessment video, explore its relationship with progesterone levels in a select in vitro fertilization population, and assess the reproducibility of the technique.

Design: Four-dimensional uterine ultrasound and a retrospective analysis of outcomes in relation with progesterone levels. The videos were also analyzed by a senior doctor, junior doctor, and a nurse for their reproducibility.

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Chronic endometritis is a pathology often associated with reproductive failure, but there are still no clear recommendations on whether its inclusion in the initial study of infertile couples is necessary. In this discussion paper, based on a SWOT (Strengths, Weaknesses, Opportunities, Threats) analysis, the different aspects of the repercussions of chronic endometritis in fertility are evaluated. To avoid possible subjectivity in the analysis and results of this study, the researchers followed the Oxford criteria for the evaluation of evidence.

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The evaluation of sperm DNA fragmentation has been postulated as a predictive molecular parameter of the semen fertilising potential, as well as the ability to give rise to a healthy embryo and an ongoing pregnancy. However, there are controversial results due to oocyte quality, the use of different measurement techniques and interpretation criteria. Our objective is to investigate if sperm DNA fragmentation on the day of fertilisation influences fertilisation (IVF) outcome in a prospective double-blind study.

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Research Question: Are discordances in non-invasive preimplantation genetic testing for aneuploidies (niPGT-A) results attributable to the technique used for chromosomal analysis?

Design: A prospective blinded study was performed (September 2018 to December 2019). In total 302 chromosomal analyses were performed: 92 trophectoderm PGT-A biopsies and their corresponding spent embryo culture medium (SCM) evaluated by two methods (n = 184), negative controls (n = 8), and trophectoderm and inner cell mass biopsies from trophectoderm-aneuploid embryos (n = 18). Trophectoderm analyses were carried out using Veriseq (Illumina), and SCM was analysed using Veriseq and NICS (Yikon).

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There is a high incidence of chromosome abnormalities in human embryos that leads to a failed IVF cycle. Different studies have shown that maternal age is the determining factor in the appearance of chromosomal alterations in the embryo. However, the possible influence of ovarian stimulation on oocyte and embryo aneuploidies and mosaicism is controversial.

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Background: The main barrier for an appropriate primary management of the reproductive health was lack of knowledge about the risk factors and prevention measures for infertility and the main recommendations was to involve primary care physicians in reproductive health.

Aims: To reach a consensus around barriers and enablers for appropriate primary management of the reproductive health.

Methods: An observational study was performed using the modified Delphi technique, from October 2017 to April 2018 in private and public assisted reproduction clinics in Spain.

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Objective: Monozygotic twinning incidence following preimplantation genetic testing in embryos at cleavage-stage does not appear to increase; however, data regarding the possible impact of the blastocyst-stage preimplantation genetic testing is lacking. We compared the incidence of monozygotic twinning in preimplantation genetic testing cycles performed at the blastocyst-stage, versus cycles without PGT, following single embryo transfer.

Methods: In this retrospective cohort study, we analyzed the incidence of twin pregnancies in patients undergoing intracytoplasmic sperm injection and blastocyst-preimplantation genetic testing (253 cycles), versus a period-matched control population of patients undergoing intracytoplasmic sperm injection and single embryo transfer without preimplantation genetic testing (606 cycles).

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