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J J Tarin

Publications and source records attributed to J J Tarin.

9 recordsLinked to original sources
PubMed1999

Effect of intracellular Ca2+ chelation with the acetoxymethyl ester-derived form of bis(o-aminophenoxy)ethane-N,N,N,N',N'-tetraacetic acid on meiotic division and chromosomal segregation in mouse oocytes.

PURPOSE: Our purpose was to ascertain the effect of intracellular Ca2+ chelation on the chromosomal distribution and segregation of mouse oocytes during maturation in vitro. METHODS: Germinal vesicle oocytes were loaded with the acetoxymethyl ester-derived form of bis(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid (BAPTA-AM). Chromosomal distribution and segregation of control and BAPTA-AM-treated metaphase II (MII) oocytes were evaluated at 16 hr, and intracellular ATP content at 0, 1, and 16 hr after BAPTA-AM loading. RESULTS: BAPTA-AM treatment decreased (P < or = 0.05) the potential for in vitro maturation, increased (P < or = 0.0001) the percentage of oocytes displaying an abnormal distribution of metaphase II chromosomes in the meiosis II spindle and aneuploidy, and decreased (P < or = 0.005) the ATP content at 0, 1, and 16 hr of culture compared to the control groups. CONCLUSIONS: These findings raise some concern about any other condition/drug that may directly or indirectly decrease the intracellular Ca2+ concentration in human oocytes.

Adenosine Triphosphate↗
PubMed1999

Origin and ploidy of multipronuclear zygotes.

Recently, several authors have proposed strategies for correction of triploidy based on the removal of the extra pronucleus at the zygote stage. In the present bioassay, the following were analysed: (1) the different factors that can induce the formation of multipronuclear zygotes in mammals; (2) the different morphological patterns established according to the number of pronuclei and polar bodies that can be observed at the zygote stage and used to distinguish the origin of multipronuclear zygotes; and (3) the pattern of chromosomal segregation during the first mitotic division and ploidy status of the resulting preimplantation embryos. Such an analysis shows that the morphological criterion of counting the number of pronuclei and polar bodies can be misleading and should not be used for ascertaining the origin of tripronuclear zygotes. In addition, although monospermic digynic zygotes have a single sperm centromere, which likely organizes a single bipolar spindle during the first mitotic division, more data on chromosomal distribution and segregation of digynic tripronuclear zygotes should be collected before strategies for correction of triploidy are implemented in humans.

Age Factors↗
PubMed1994

Characterization and prediction of IVF cycles generating "slow-cleaving" embryos.

PURPOSE: To characterize and predict cycles generating open quote slow-cleaving closed quote embryos in in vitro fertilization, 86 cycles were retrospectively divided into two groups (open quote slow, closed quote n=41, and open quote fast, closed quote n=45) according to whether the number of blastomeres per embryo on day 3 was < or = or > than the mean of the distribution, respectively. RESULTS: Cycles generating open quote slow-cleaving closed quote embryos were treated with luteinizing hormone-releasing hormone agonist before ovarian stimulation for a shorter period (12.1 +/- 0.5 versus 15.6 +/- 1.1 days; P < or = 0.01) and had higher immaturity grade of oocyte-corona-cumulus complexes which resulted in embryos (1.6 +/- 0.1 vs 1.3 +/- 0.1; P < or = 0.05) when compared to cycles producing "fast-cleaving" embryos. Both variables entered in a logistic regression model applied in order to predict the probability of a cycle generating "slow-cleaving" embryos (goodness-of-fit chi-square = 180.0, degrees of freedom (df) = 80, P = 0.4786). This model predicted correctly 86.7% (13 of 15) of cycles generating "slow-cleaving" embryos and 83.3% (10 of 12) of cycles producing "fast-cleaving" embryos when the estimated probability of a cycle producing "slow-cleaving embryos" was > or = 0.7 or < or = 0.3, respectively. CONCLUSION: Shorter treatment with hormone-releasing hormone agonist before ovarian stimulation and higher immaturity grade of oocyte- corona-cumulus complexes which result in embryos are predictive characteristics of in vitro fertilization cycles generating "slow-cleaving" embryos.

Adult↗
PubMed1992

The use of gonadotrophin releasing-hormone analogues (GnRHa), in in-vitro fertilization: some clinical and experimental investigations of a direct effect on the human ovary.

Several lines of investigation suggest a direct modulatory role for gonadotrophin-releasing hormone (GnRH) on granulosa cell functions. Also, GnRH and its analogues (GnRHa) have been implicated in the resumption of meiosis, both in vivo and in vitro. Despite the presence of specific receptors for GnRH on human granulosa and luteal cells, very little is known about the possible effects of this hormone on the ovary. The use of GnRHa for long periods of time in patients undergoing in vitro fertilization (IVF) may influence granulosa cell function and/or oocyte maturation. We describe our clinical and experimental data in which we have searched for evidence of a direct action of GnRHa on the ovary. We have found that the retrieval of higher numbers of oocytes in women treated with GnRHa is correlated with oocytes of lower quality, manifested by a decreased fertilization and implantation rate. This impairment seems to be the consequence of oocyte immaturity, as ascertained by cytogenetic analysis of unfertilized oocytes in which an increase in diploidy, as well as prematurely condensed sperm chromosomes of the G1 phase, was observed in women with an excessive response to the stimulating drugs. Follicular atresia was not increased in women treated with GnRHa. Thus, there was no evidence for a direct effect of GnRHa on the human oocyte. Rather, the observations reflect the harmful effect of pushing follicles in early stages of development using this stimulation protocol. We have also searched for possible effects of GnRHa on granulosa-luteal cells obtained at ovum collection. In vitro culture of these cells has shown that the steroidogenic pathway is affected.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Count↗
PubMed1992

Steroidogenesis in vitro of human granulosa-luteal cells pretreated in vivo with two gonadotropin releasing hormone analogs employing different protocols.

We have previously observed impaired progesterone accumulation in vitro in response to human chorionic gonadotropin (hCG) by cells pretreated in vivo with a gonadotropin releasing hormone analog (GnRH-a). The present study was conducted in order to evaluate different protocols for GnRH-a in in vitro fertilization (IVF), employing two different available analogs. Granulosa-luteal cells were collected at ovum pick-up and stimulated with hCG. Buserelin (Bus) was employed as long (Bus-L) and short (Bus-S) protocol, and Leuprolide (Leu) was also used as long (Leu-L) and short (Leu-S) protocol. Progesterone accumulation in vitro was compared with cells treated with clomiphene citrate (CC) and gonadotropins. Maximal progesterone production was observed on culture day 6 using Bus-L in comparison to day 4 when clomiphene citrate was employed. While Leu-S showed a similar pattern of progesterone accumulation to clomiphene citrate, Leu-L and Bus-S had an intermediate pattern. The response to hCG was maximal on day 4 for the clomiphene citrate- and Leu-S-treated cells, while the rest of the protocols had a peak on day 6. In addition, hCG consistently stimulated progesterone production in all protocols except in Bus-L. These results confirm an altered progesterone accumulation in vitro when GnRH-a are used. The effect seems to be more evident in long protocols, especially when buserelin is used, suggesting a higher accumulation of the analog in follicular fluid.

Buserelin↗
PubMed1989

Is the retrieval of high numbers of oocytes desirable in patients treated with gonadotrophin-releasing hormone analogues (GnRHa) and gonadotrophins?

Continuous administration of gonadotrophin-releasing hormone analogues (GnRHa) in patients stimulated for the purpose of IVF might have a direct effect on the ovary. We have evaluated the IVF outcome of patients treated with Buserelin and subsequently with a combination of follicle-stimulating hormone (FSH) and human menopausal gonadotrophin (HMG). Patients were divided into three groups according to the number of oocytes obtained by transvaginal ultrasound-guided follicular aspiration: group 1 (n = 35), in which 1-5 oocytes were retrieved; group 2 (n = 30), in whom 6-10 oocytes were obtained; group 3 (n = 32), in whom greater than or equal to 11 oocytes were collected. Only couples with normal semen samples at oocyte retrieval were included in this study. The dose of Buserelin employed was not different between groups. However, the amount of FSH/HMG necessary to reach an optimal response significantly (P less than 0.01) decreased as follicular development increased. The quality of the oocytes obtained was evaluated based on the appearance of the oocyte-corona-cumulus complex, fertilization rate, morphological appearance of the embryos, and implantation rate. The fertilization rate was significantly (P less than 0.01) decreased in group 3 (57.2%) in comparison with groups 1 (77.1%) and 2 (74.2%). There was no significant difference between the groups in the quality of the embryos obtained or the quality of those replaced into the uterus. The implantation rate per embryo transferred was significantly (P less than 0.05) higher in group 1 (16.5%) in comparison with groups 2 (6.6%) and 3 (8.2%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Development of the human dispermic embryo.

In a recent CD-ROM, we portrayed the microstructure of the pre-implantation human embryo (Sathananthan et al., 1999), which was a multimedia production with computer colour-enhanced electron micrographs of mainly monospermic embryos. This disk portrays light and electron micrographs of over 250 tripronuclear (3PN), dispermic, human embryos during pre-implantation development, viewed in thick and thin Araldite sections, as well as appearances of whole embryos flat embedded in Araldite blocks visualized with the light microscope. The 100 figures were computerized (IBM TIFF format), edited and labelled using Adobe Photoshop 5. Some of the figures were coloured on computer. The early development of 3PN embryos overtly resembles that of normal embryos but there are important differences in their microstructure which are portrayed in this presentation. This is a multicentric study involving researchers from four IVF centres.

Aneuploidy↗