Biomedical subjects

J Remohí

Publications and source records attributed to J Remohí.

96 records · Page 6Linked to original sources

PubMed1991

Cytogenetic analysis of human oocytes from fertile women.

Several reports have shown a relatively high incidence of chromosome anomalies in human inseminated-unfertilized oocytes from infertile women. In the present study, cytogenetic analysis was attempted in 73 human oocytes from 17 fertile women in order to establish the incidence of chromosome anomalies in the fertile population and to compare this with the incidence in inseminated-unfertilized oocytes from infertile women. Of 56 oocytes that could be analysed, 42 oocytes were haploid, 12 were hypohaploid and two exhibited fragmented chromosomes. The low rate of chromosome anomalies (3.6%) found in this population suggests that there is natural selection at fertilization against diploid oocytes and oocytes with fragmented chromosomes. This result also questions the high incidence of chromosome anomalies found in previous reports using inseminated-unfertilized oocytes.

Chromosome Aberrations↗

PubMedDate not supplied

Concentration of glutathione and expression of glutathione peroxidases 1 and 4 in fresh sperm provide a forecast of the outcome of cryopreservation of human spermatozoa.

Oxidative stress imbalance potentially leads to damage of the structure of the cell and macromolecules such as plasma membrane components, proteins, and DNA. The plasma membrane of the sperm cell, which has high levels of polyunsaturated fatty acids, renders it particularly sensitive to free radical-mediated attacks. The freezing and subsequent thawing of sperm is a physically stressful process carried out during routine procedures in assisted reproduction techniques, which results in a highly variable and unpredictable reduction in the number of motile sperm cells. Subsequently, oxidative status can positively or negatively affect the motility, viability, and fertilizing capacity of thawed sperm. These effects are counteracted by various oxidative defense enzymes and anti-oxidants such as glutathione peroxidase isoforms GPx1 and GPx4, glutathione reductase (GR), and cellular glutathione (reduced) (GSH). In this way, oxidative status could represent a predictive marker of sperm quality following the freeze-thaw process. This study was based on 56 human sperm samples. We observed direct positive and negative relationships between the postthaw motile sperm recovery rate and GPx1 and GPx4 expression and activity, on the one hand, and GSH concentrations, on the other. No correlation was found between this recovery rate and GR or basic semen parameters. Predictive values clearly demonstrate that, among the molecules analyzed, the most accurate diagnoses result when analyses are conducted for GPx1 and GPx1 messenger RNA expression, GPx1 and GPx4 enzymatic activity, and GSH concentration. In conclusion, a reserve of glutathione, together with GPx expression, is necessary to eliminate free radicals using GSH or a like structural protein and seems to be essential for a good postthaw recovery. These molecules can be employed as indicators of postthaw sperm quality.

Cryopreservation↗

PubMedDate not supplied

New techniques on embryo manipulation.

For many years, experience has been accumulated on embryo and gamete manipulation in livestock animals. The present work is a review of these techniques and their possible application in human embryology in specific cases. It is possible to manipulate gametes at different levels, producing paternal or maternal haploid embryos (hemicloning), using different techniques including nuclear transfer. At the embryonic stage, considering practical, ethical and legal issues, techniques will be reviewed that include cloning and embryo splitting at the cleavage stage, morula, or blastocyst stage.

Animals↗

PubMedDate not supplied

Human endometrial receptivity: a genomic approach.

The endometrium is a specialized tissue, hormonally-regulated, that is non-adhesive for embryos throughout most of the menstrual cycle in humans and other primates. Thus, endometrial receptivity is a self-limited period in which the endometrial epithelium (EE) acquires a functional and transient ovarian steroid-dependent status. The luminal EE acquires the ability to adhere (receptivity) the developing human blastocyst during this period due mainly to the presence of progesterone after appropriate 17beta-oestradiol priming. This status is a key element for embryonic implantation and appears to be closely associated with morphological and biochemical changes of EE cells. This specific time window is thought to be open after 4-5 days and closes after 9-10 days of progesterone production or administration, creating a physiological window of receptivity limited to days 19-24 of the menstrual cycle in humans. The scientific knowledge of the endometrial receptivity process is fundamental for the understanding of the human reproduction, but, so far, none of the proposed biochemical markers for endometrial receptivity have been proved clinically useful. In this work new strategies are presented based on molecular biology technologies that aim to clarify the fragmented information in this field using differential display, quantitative PCR and cDNA microarray analysis of endometrial epithelial-derived cell lines and endometrial samples to investigate the hierarchy at the mRNA level of molecules implicated in the process of endometrial receptivity.

Blastocyst↗

PubMedDate not supplied

Follicular hormonal environment and embryo quality in women with endometriosis.

The use of in-vitro fertilization (IVF) as a therapeutic tool in patients with endometriosis has provided information about the disease and, in particular, aspects of the reproductive process in humans, particularly folliculogenesis, fertilization, embryo development and implantation. Retrospective analyses of IVF and oocyte donation programmes showed impaired implantation in patients with endometriosis. Otherwise, the observation that embryo development was blocked more frequently in cases of endometriosis, suggested that impaired embryo quality may be responsible for the reduced implantation rates. Similarly, women with the disease undergoing oocyte donation had the same chance of implantation as patients without endometriosis, suggesting that the endometrial milieu is not affected in patients with endometriosis. The quality of the oocyte may, therefore, be altered in patients with endometriosis. To investigate this, we studied steroid secretion in women undergoing IVF. Progesterone concentrations in follicular fluid increased with the severity of the disease and an increase in progesterone accumulation in vitro was observed in basal and human chorionic gonadotrophin (HCG)-induced granulosa cell cultures. We postulated that the pattern of progesterone secretion may be related to the release of cytokines by ovarian and/or immune cells. To test this, we measured interleukin (IL)-1, IL-6 and vascular endothelial growth factor (VEGF) concentrations in serum, follicular fluid and granulosa cell cultures. IL-6 concentrations in serum were increased in natural cycles in women with endometriosis and showed a significant decrease in stimulated cycles in IVF. Also, IL-6 concentrations were increased in the follicular fluid of women with endometriosis and released in higher amounts by granulosa-luteal cells from patients with endometriosis. VEGF was accumulated in lower concentrations in the follicular fluid of endometriosis patients. These observations show that the follicular environment is different in cases with endometriosis and suggest that infertility in patients with endometriosis may be related to alterations within the oocyte which, in turn, result in embryos of lower quality, and with a reduced ability to implant.

Embryo Implantation↗

PubMedDate not supplied

Screening for AZF deletion in a large series of severely impaired spermatogenesis patients.

Recent investigations have pointed to a high prevalence of Y chromosome submicroscopic deletions in men with severely impaired spermatogenesis. We report on the incidence in 128 infertile men, in whom karyotype, sperm count, and hormonal parameters were evaluated. Patients with abnormal karyotype (other than an abnormal Y chromosome) or sperm concentration of more than 2 million/mL were excluded. Genomic DNA was extracted from the peripheral leukocytes of 57 men with azoospermia and 71 with severe oligospermia. Molecular analysis was performed by 3 multiplex polymerase chain reactions using a set of 9 sequence tagged sites (STSs) from 3 different regions of the Y chromosome: AZFa, AZFb, and AZFc. In 7% of the studied patients Yq microdeletions were detected, with a high prevalence in men with azoospermia (14%). No deletions were detected in the AZFa region. Deletions were present in AZFb, AZFc, or both regions. The deletion observed in 1 patient that did not overlap with the DAZ region demonstrates that genes other than DAZ may also be involved in the pathogenesis of some subsets of male infertility. Furthermore, common Yq deletions present different testicular pictures, suggesting that some unknown factors may be disturbing spermatogenesis. Because men with severe infertility suffer a high risk of Y chromosome deletion, screening for these men is recommended prior to treatment with assisted reproduction.

Chromosome Aberrations↗