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C Simón

Publications and source records attributed to C Simón.

141 records · Page 8Linked to original sources
PubMed1988

Mapping and sequence of the gene encoding protein p37, a major structural protein of African swine fever virus.

The gene encoding protein p37, one of the major structural proteins of African swine fever (ASF) virus has been mapped and sequenced. Protein p37 was obtained from purified virions and the first 27 amino acids from its NH2-terminal end were identified by automatic Edman degradation. To map the gene encoding protein p37, a mixture of 20-mer deoxyoligonucleotides based upon a part of this amino acid sequence was hybridized to cloned ASF virus restriction fragments. This allowed localization of the gene in fragment KpnI F/HindIII G1 of the African swine fever virus genome. An analysis of the DNA sequence from this region revealed an open reading frame encoding 418 amino acids. In this sequence, the 27 NH2-terminal amino acids determined by sequence analysis of protein p37 are preceded by a stretch of 132 amino acids residues, indicating that protein p37 is synthesized as a polypeptide of higher molecular weight and then post-translationally processed by cleavage of a Gly-Ala bond. This processing event accounts for the antigenic relationship of protein p37 to a virus-induced, nonstructural protein with a relative molecular weight of 60 kD.

African Swine Fever Virus↗
PubMed1987

Granular cell myoblastoma (GCM): contribution of three cases with genital involvement.

Granular cell myoblastoma (MGC) is an uncommon benign tumor of mesodermal origin of which no more than sixty cases with genital involvement have been reported. Among the genital organs, the labium majus of the vulva are the predilect site. We hereby contribute three new cases with a genital location (two in the vulva and one in the breast) and review the literature on the subject.

Adolescent↗
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

An assessment of hysterosalpingosonography (HSSG) as a diagnostic tool for uterine cavity defects and tubal patency.

The value of hysterosalpingosonography (HSSG) as a diagnostic tool was evaluated in 76 patients and compared to hysteroscopic, laparoscopic, and/or hysterosalpingographic (HSG) findings. Saline solution and Dextran 60 were used as distension media. Patients were divided in three groups: group A (n = 22), patients submitted for control post-tubal electrocoagulation. Group B (n = 38), patients with a history of pathological metrorrhagias, and group C (n = 16) infertile women with possible tubal pathology. Comparison between the different diagnostic techniques for the evaluation of the uterine cavity and tubes was carried out. Our results indicated that HSSG had more sensitivity but less specificity than hysteroscopy or HSG in the diagnosis of uterine cavity pathology. Hysteroscopy seems to be the best technique for the diagnosis of endometrial pathology, and HSSG seems to be the most effective in the study of the myometrium. HSSG cannot be considered a reliable and accurate method for the diagnosis of tubal patency.

Adult↗
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

Leptin and reproduction.

Leptin, the product of the ob gene, is a small peptide molecule synthesized by white adipocytes with an important role in the regulation of body fat and food intake. Leptin and leptin receptor mRNA were first detected in the brain and hypothalamus but now their ubiquitous presence has been demonstrated. Leptin receptor signal transduction involves the activation of signal transducer and activator of transcription (STAT)-3, a member of the transcription family of proteins. Leptin is regulated by hormones and cytokines, interleukin-1, tumour necrosis factor-alpha and transforming growth factor-beta, linking this molecule with the inflammatory response. In addition, emerging evidence has demonstrated that this molecule is related to reproductive function. This small protein is present in the ovary and decidua, in mature oocytes and during embryonic development and trophoblast invasion. Animal models have demonstrated that leptin-deficient ob/ob mice are sterile; however, fertility can be restored by exogenous leptin. In addition, embryos implanted in STAT-3-deficient mice degenerate rapidly and are the target disruption of STAT-3-provoked embryonic lethality. Leptin acts as a novel placental hormone participating in the control of fetal growth and development. Leptin could be a modulator for invasive features of cytotrophoblast cells. We postulate that leptin may have an autocrine/paracrine role in human implantation and placentation.

Animals↗
PubMedDate not supplied

The endometrium versus embryonic quality in endometriosis-related infertility.

In spite of a great deal of effort over many decades, the mechanisms that lead to infertility in women with endometriosis remain unknown. Moreover, controversial results in the literature add even more difficulties in the understanding of this issue. Since the introduction of IVF, we have had the opportunity to study the effects of endometriosis at specific stages of the reproductive process including folliculogenesis, fertilization, embryo development and implantation. Depending on the research group, there are conflicting data on the results of IVF in patients with endometriosis. Some researchers found impaired implantation in patients with endometriosis, but such a defect in implantation may be caused by either defective embryos or altered endometrium. The observation of a higher rate of arrested embryos in patients with endometriosis compared with disease-free women, and that women with this pathological situation undergoing ovum donation had the same chance of implantation as patients without endometriosis, initially suggested that impaired oocyte/embryo quality may be responsible for reduced implantation. Further investigations on follicular components have also found differences between women with endometriosis and those without the disease. In addition, recent advances on implantation research, mainly on markers of endometrial receptivity, also show features in the eutopic endometrium of women with endometriosis that are not found in endometrium of women without the disease, although there is no agreement on this point. In this review, we will focus on infertility-related endometriosis based on our own research and the available literature.

Embryo, Mammalian↗
PubMedDate not supplied

Detection of apoptosis in human and rat ovarian follicles.

OBJECTIVE: The purpose of this study was to determine whether cells acquired from individual human preovulatory follicles undergo apoptosis (physiologic cell death) and, if so, to correlate the degree of apoptosis with characteristics of the follicles or the oocytes derived from the follicles. METHODS: We devised a sensitive nonradioactive method for detecting apoptotic DNA fragmentation in small numbers of cells derived from rat atretic follicles and follicular aspirates of patients undergoing assisted reproductive technologies. RESULTS: Using this method, apoptotic DNA was detected in rat atretic follicles, with optimal detection at 10-100 ng. Furthermore, apoptotic DNA was detected in some, but not all individual human follicular aspirates from several patients, and was found in follicles that produced oocytes that fertilized and developed into embryos. CONCLUSION: Apoptosis occurs in cells from human ovarian preovulatory follicles and may be a normal physiologic process of the follicle during luteinization.

Animals↗