Ricardo Pommer

University of Santiago, Chile, CiudadSantiago, Santiago, Chile

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Publications (18)51.9 Total impact

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    ABSTRACT: Several reports indicate that women who smoke have an increased risk of failure to conceive compared with their non-smoker counterparts. Here, we assessed the effect of smoking during the Assisted Reproduction Therapy (ART) on a potential marker of ovarian reserve, anti-müllerian hormone (AMH) in the follicular fluid (FF). This was a cohort prospective study to assess the association between cigarette smoking and AMH concentrations in FF in fifty-six women undergoing their first ART cycle. Self-reported smoking status over time was also collected through personal interview. The main outcome measured was the association between current smoking and AMH concentrations in FF. Smoking status was assessed by FF cotinine concentrations. Analysis of covariance was performed to test statistical interaction between the main outcome and confounders. The mean concentration of AMH in follicular fluid was significantly decreased among smokers (1.02±0.14 vs. 1.74±0.15, P<0.05). No statistical interaction was found between this difference in AMH concentrations and confounders like age and BMI. Thus, our data support the idea that AMH is decreased in active smokers across the fertile age. The hypothesis of decreased AMH concentration in follicular fluid in female smokers was confirmed. The mechanisms through which cigarette smoking induces this fall in AMH are unknown and additional research is needed to improve our comprehension of the negative impact of smoking on ART outcomes.
    Chemosphere 03/2012; 88(4):403-6. · 3.14 Impact Factor
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    ABSTRACT: Multiple pregnancies are the main complication associated to assisted reproduction, due to the transfer of more than one embryo. Embryo cryopreservation allows the sequential transfer of all generated embryos, thus diminishing the risk of multiple pregnancies. However, it leads to accumulation of cryopreserved embryos. To reduce their accumulation in our unit, we started to preserve embryos as blastocysts, that have a rate of successful pregnancies of approximately 40%. To perform a sensitivity analysis of this change of policy on the accumulation of embryos. Records of 571 cycles of in vitro fertilization since 2007 were reviewed, assuming a transference rate of two embryos in women aged less than 35 years and three embryos in older women. The number of embryos that would be preserved as zygotes, eight cell stage or blastocysts, was analyzed. Multiple component logistic regression analysis showed a 20% reduction in the odds ratio of cryopreservation per year of age. There was a 95% reduction in the ratio, when comparing the preservation of third and first day embryos and a 99% reduction when comparing preservation of embryos in blastocyst stage and first day embryos. Cryopreservation at blastocyst stage effectively decreased the frequency of embryo cryopreservation.
    Revista medica de Chile 01/2012; 140(1):45-9. · 0.36 Impact Factor
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    Revista medica de Chile 01/2012; 140(1):45-49. · 0.36 Impact Factor
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    ABSTRACT: DAX-1 [dosage-sensitive sex reversal-adrenal hypoplasia congenital (AHC) critical region on the X chromosome gene 1; NR0B1] is an orphan nuclear receptor that acts as a transcriptional repressor in adrenal/gonadal development, steroidogenesis and probably spermatogenesis. An alternatively spliced form called DAX-1A (NR0B1A) has been described in several tissues including the testis, and in vitro studies have shown an inhibitory effect on DAX-1 transcriptional function. We aimed to study the mRNA and protein expression of DAX-1 in testicular tissues of 65 men with primary spermatogenic failure [complete Sertoli cell only syndrome (SCOS), focal SCOS, maturation arrest and mixed atrophy] compared with 33 controls with normal spermatogenesis. As a novel finding, we observed intense immunostaining, not only in the nucleus of Sertoli cells, but also in pachytene spermatocytes and round spermatids. The quantitative mRNA expression of DAX-1 and DAX-1A was similar between cases and controls and was not associated with the levels of gonadotrophins and steroids. Moreover, DAX-I transcript expression level was ∼750-fold higher than DAX-1A, and there was a strong positive correlation between them (r = 0.52; P< 0.001). We conclude that, in addition to Sertoli cells, DAX-1/DAX-1A is expressed in germ cells from spermatogonia to round spermatids. Besides, the similar mRNA expression of DAX-I and DAX-IA in testicular tissues from cases and controls does not support the involvement of DAX-1 in the etiology of primary spermatogenic failure. Finally, the low level of expression of the alternative transcriptional variant DAX-1A would not support its putative inhibitory function in vivo.
    Molecular Human Reproduction 07/2011; 17(12):739-46. · 4.54 Impact Factor
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    ABSTRACT: We report the first successful live birth after the transfer of embryos obtained by fertilization of vitrified oocytes. A couple with primary infertility due to teratozoospermy and chronic an ovulation decided to undergo assisted reproductive technology after 4 failed cycles of super ovulation and intrauterine insemination. The woman underwent a standard luteal phase agonist protocol, with controlled ovarian hyper stimulation with daily 150 IU recombinant gonadotropin and 75 IU urinary gonadotropin for 12 days. Due to the high risk of ovarian hyper stimulation syndrome the couple was advised to delay embryo transfer. Eighteen mature oocytes were recovered, eight were vitrified and 10 fertilized and cryopreserved as pro-nuclei. Two months later, four vitrified oocytes were thawed, and three morphologically-normal embryos were transferred to an estrogen-progesterone-primed uterus, obtaining triple clinical pregnancy. The pregnancy was uneventful until 32 weeks of amenorrhea, when pre-term delivery started. After inducing lung maturity, a cesarean section was performed and three healthy fetuses were delivered. Nowadays, the babies are two and a half years old, and have had a normal psycho-motor development.
    Revista medica de Chile 07/2011; 139(7):920-3. · 0.36 Impact Factor
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    Revista medica de Chile 07/2011; 139(7):920-923. · 0.36 Impact Factor
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    ABSTRACT: There is evidence that impaired spermatogenesis is associated with an imbalance in the oestradiol/testosterone ratio and with Leydig cell (LC) dysfunction. In testis, P450-aromatase, encoded by CYP19, is responsible for the conversion of testosterone to oestradiol. The aims of this study were to quantify CYP19 mRNA expression, aromatase activity and protein localization, and to measure the oestradiol to testosterone ratio in testicular tissues of men with spermatogenic impairment. Twenty-four men with complete Sertoli cell-only syndrome (SCOS), 14 with focal SCOS, 14 with maturation arrest (MA), 8 with mixed atrophy and 30 controls with normal spermatogenesis were subjected to testicular biopsy. All subjects underwent a physical examination, cytogenetic and serum hormonal studies. Testicular CYP19 mRNA was quantified using real time RT-PCR. Testicular aromatase activity was measured using the (3)H(2)0 assay and protein expression was evaluated using immunohistochemistry. In cases, serum testosterone and oestradiol were normal, but the testosterone/LH ratio was lower compared with controls (p < 0.05). Aromatase was localized in the Leydig, Sertoli and germ cells of all tissues, although stronger intensity was observed in LC. Aromatase mRNA and activity were not altered in cases and correlated positively with LC number (r = 0.516 and r = 0.369; p < 0.008). The intratesticular oestradiol/testosterone ratio was elevated (p = 0.005) in complete SCOS patients compared with controls. In conclusion, testicular aromatase seems to be normal in most subjects with impaired spermatogenesis. However, an altered intratesticular oestradiol/testosterone ratio in some patients with complete SCOS suggests that aromatase is increased, which might contribute to Leydig cell dysfunction.
    International Journal of Andrology 11/2009; 33(4):650-60. · 3.37 Impact Factor
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    ABSTRACT: To assess the association between recent cigarette smoking (CS) in female and male partners and assisted reproduction technology (ART) outcomes. Cohort prospective study. University ART program in Chile. One hundred sixty-six couples seeking pregnancy through ART. Follicular fluid (FF) and serum cotinine concentrations were measured in female partners. Self-reported CS data were collected through personal interviews. The association between female recent smoking, assessed by FF and serum cotinine concentrations, and ART outcomes, such as number of ova retrieved and implantation rates, and the association between self-reported male recent smoking and live birth rates. A significant age-adjusted association between increased FF cotinine level and decreased number of ova retrieved was found. The male partner's smoking habit significantly decreased the live birth rate from 21.1% to 7.8%. Serum cotinine concentrations paralleled those of FF. The hypothesis of a detrimental effect of recent female smoking over implantation rates is rejected. However, recent male smoking is associated with significantly decreased live birth rates even after adjusting for confounders. Female recent smoking was significantly associated with decreased number of retrieved ova.
    Fertility and sterility 11/2008; 93(1):89-95. · 3.97 Impact Factor
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    ABSTRACT: To summarize recent advances in the understanding of the endocrine signaling pathways between the hypothalamus, pituitary, and human corpus luteum (CL); to examine the major paracrine and autocrine mechanisms and the key genes and proteins involved in CL development, function, and regression in natural cycles; to review the endocrine and molecular response of the midluteal phase CL to in vivo administration of human chorionic gonadotropin (hCG); and to describe the ultrasonographic and Doppler evaluation of the ovary and endometrium throughout the luteal phase. Published data in the literature, including the basic and clinical research studies of the authors. University-affiliated hospital and research centers. None. None. Clinical and molecular analysis of human CL function. The endocrine function of the subpopulations of luteal cells is critical for the maintenance of CL function, including neovacularization and steroid hormones production. We consider the key genes and proteins that favor development of luteal structure and function throughout the menstrual cycle and in our model of hCG treatment resembling early pregnancy. These data indicate that the functional lifespan of the CL depends on paracrine and autocrine mechanisms. Therefore, the significance of the key genes and proteins that we analyze in lutein cells during CL development, function, demise, and rescue by hCG is likely to bring new therapeutic applications for the management of fertility defects and the control of fertility.
    Fertility and sterility 10/2008; 92(3):1067-79. · 3.97 Impact Factor
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    ABSTRACT: To determine whether the incidence of apoptosis in mature oocyte cumulus cells changes after insemination related to infertility. Prospective study. Public hospital and university. One hundred women undergoing in vitro fertilization and embryo transfer (IVF-ET). Collection of cumulus cells from IVF-ET cycles with different infertility etiologies. Detection of apoptosis in cumulus cells; fertilization, embryo quality, and pregnancy rate. The incubation of cumulus-oocyte-complexes with spermatozoa led to an increase in cumulus cell apoptosis from 34.2 +/- 3.7 to 44.5 +/- 6.3%. After insemination, cumulus cells of poor quality embryos showed a statistically higher apoptotic rate versus cumulus cells of good quality embryos (61.5 +/- 6.4 vs. 40.6 +/- 3.9%). Cumulus cells arising from oocytes with >or=50% fertilization rates after insemination showed higher apoptosis rates did cumulus cells from oocytes with <50% fertilization rates (46.0 +/- 3.7 vs. 33.8 +/- 4.0%). Patients with endometriosis presented higher apoptotic rates before insemination (77.6 +/- 9.06%). Cumulus cells obtained after aspiration showed no differences in their apoptosis rates for the following factors: age of women, aspirated oocytes, estradiol level, fertilization rate, and embryo quality or pregnancy. The apoptotic profile from pregnant women was less than (but not statistically significantly different from) profiles from nonpregnant women. These results suggest that the incidence of apoptosis in cumulus cells is associated with exposure to spermatozoa and the cause of infertility.
    Fertility and sterility 08/2008; 91(5 Suppl):2061-8. · 3.97 Impact Factor
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    ABSTRACT: Gene expression profiling of normal receptive endometrium has been characterized, but intrinsic defects in endometrial gene expression associated with implantation failure have not been reported. Women who had previously participated as recipients in oocyte donation cycles and repeatedly exhibited implantation failure (Group A, study group) or had at least one successful cycle (Group B, control group) and spontaneously fertile women (Group C, normal fertility group) were recruited. All were treated with exogenous estradiol and progesterone to induce an endometrial cycle, and an endometrial biopsy was taken on the seventh day of progesterone administration. RNA from each sample was analysed by cDNA microarrays to identify differentially expressed genes between groups. 63 transcripts were differentially expressed (>or=2-fold) between Groups A and B, of which 16 were subjected to real time RT-PCR. Eleven of these were significantly decreased in Group A with regard to Groups B and C. Among the dysregulated genes were MMP-7, CXCR4, PAEP and C4BPA. Repeated implantation failure in some oocyte recipients is associated with an intrinsic defect in the expression of multiple genes in their endometrium. Significantly decreased levels of several transcripts in endometria without manifest abnormalities is demonstrated for the first time and shown to be associated with implantation failure.
    Human Reproduction 03/2008; 23(2):340-51. · 4.67 Impact Factor
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    ABSTRACT: Y chromosome microdeletion is the most important genetic cause of impairment of spermatogenesis. Nevertheless, a significant proportion of patients with spermatogenic failure do not have this condition. This study investigated the expression level of AZF genes, DDX3Y (DBY), RBMY1, DAZ and TSPY in testicular tissues of 42 subjects with impaired spermatogenesis compared with 33 with normal spermatogenesis. Histopathological evaluation was performed in all subjects and tissues were classified according to Johnsen Score. Transcript amounts were determined by quantitative-competitive RT-PCR. Patients with complete Sertoli cell-only syndrome (SCOS) did not exhibit RBMY1, DAZ and TSPY gene expression, however, we detected very low expression of DDX3Y transcript. Tissue samples with focal SCOS showed significantly decreased expression of all genes (P < 0.001). Maturation arrest and hypospermatogenesis tissues expressed significantly low levels of DDX3Y testicular transcript (P < 0.001), while the mRNA levels of the other genes were similar to that in tissues from the normal spermatogenesis group. Negative or diminished gene expression of DDX3Y, RBMY1, DAZ and TSPY in tissues samples with SCOS or focal SCOS reflects the absence or the lower number of germ cells, respectively. The finding that the testicular transcript of DDX3Y is significantly decreased in patients with severe spermatogenenic failure, especially in those presenting maturation arrest, suggests an important role of DDX3Y during spermatogenesis.
    Molecular Human Reproduction 11/2007; 13(10):705-12. · 4.54 Impact Factor
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    ABSTRACT: To determine the prevalence of AZFc subdeletions in infertile Chilean men with severe spermatogenic impairment. Prospective analysis. University infertility clinic. Ninety-five secretory azo/oligozoospermic men without AZFc Y chromosome microdeletions: 71 whose testicular histology showed severe spermatogenic impairment and 24 who exhibited reduced testicular volume and elevated serum FSH levels. As controls, we studied 77 men (50 fertile and/or normozoospermic, and 27 with azoospermia and normal spermatogenesis). Peripheral blood was drawn to obtain genomic DNA for polymerase chain reaction (PCR) digestion assays of DAZ-sequence nucleotide variants and for AZFc-STS PCR after a complete testicular characterization (biopsy, hormonal, and physical evaluation). DAZ genes and AZFc subdeletion types. In cases we observed two "gr/gr" subdeletions (2.1%), one with absence of DAZ1/DAZ2 (g1/g2 subtype), and the other with absence of DAZ3/DAZ4 (r2/r4 subtype). Additionally, we found a g1/g3 subdeletion in a patient with Sertoli-cell-only syndrome. In controls, we observed two gr/gr subdeletions with absence of DAZ1/DAZ2 (2.6%) in a fertile/normozoospermic and in an obstructive azoospermic man. AZFc subdeletions do not seem to cause severe impairment of spermatogenesis. Moreover, gr/gr-DAZ1/DAZ2 subdeletions do not appear to affect fertility in Chilean men.
    Fertility and sterility 11/2007; 88(5):1318-26. · 3.97 Impact Factor
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    ABSTRACT: The role of tumor necrosis factor-alpha (TNF-alpha) in granulosa luteal cell function and steroidogenesis is still controversial. Our aim was to examine the steroidogenic response, together with the simultaneous expression and activation of nuclear factor-kappaB (NF-kappaB), in cultured human granulosa luteal cells (GLCs) following administration of TNF-alpha. This prospective controlled study was conducted in the Human Reproduction Division at the Institute of Maternal and Child Research, Faculty of Medicine, University of Chile and the San Borja Arriarán Hospital, National Health Service, Santiago, Chile. GLCs were obtained from aspirates of follicles from women undergoing in vitro fertilization (IVF). Thirty-two women undergoing IVF for tubal-factor and/or male-factor infertility participated in this study. Protein levels of NF-kappaB, the NF-kappaB inhibitor IkappaBalpha and steroidogenic acute regulatory protein (StAR) were determined by Western blot and localization of NF-kappaB was studied by indirect immunofluorescence. Progesterone production was determined by radioimmunoassay. TNF-alpha did not affect the expression of StAR protein or the synthesis of progesterone. NF-kappaB was expressed in the GLCs and activated by TNF-alpha, resulting in degradation of IkappaBalpha and mobilization of the p65 NF-kappaB subunit into the nucleus. These results indicate that TNF-alpha did not modulate steroidogenesis in cultured human GLCs. However, NF-kappaB was activated by TNF-alpha. Therefore the activation of NF-kappaB via the TNF-alpha pathway is likely associated with other preovulatory granulosa cell processes important for human ovarian function.
    Gynecological Endocrinology 08/2007; 23(7):377-84. · 1.30 Impact Factor
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    ABSTRACT: The present study assesses the endocrinological, endometrial histology and vaginal ultrasound profiles of nomegestrol acetate subdermal implant users at varying times after insertion. Follicle stimulatory hormone, luteinizing hormone, oestradiol, progesterone, vaginal ultrasound assessment of the ovaries and the histological dating of the endometrium were serially assessed for a period of 50 days immediately after the insertion, and after at 6 months and 12 months of use. The endocrinological results of this prospective observational clinical trial indicated that 75% of the cycles across the study period in Uniplant users were anovulatory, 63% showing development of a persistent non-luteinized follicle. Anovulatory cycles devoid of follicular development were seen primarily in the first months after Uniplant insertion. Ovulatory cycles represented 25% of the Uniplant cycles. Inadequate luteal phase or disregulation of follicular growth was a common feature of ovulatory cycles. In conclusion, these findings suggest that the contraceptive mechanisms of a single nomegestrol acetate subdermal implant involve prevention of follicular growth, development of a persistent non-luteinized follicle, inadequate luteal phase and disruption of the endometrial architecture.
    Human Reproduction 05/1997; 12(4):708-13. · 4.67 Impact Factor
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    ABSTRACT: OBJECTIVE: To evaluate the effect of menstrual changes induced by a nomegestrol acetate subdermal contraceptive implant (Uniplant; Thermex, Bahia, Brazil) on users' sexuality. DESIGN: Prospective observational survey. SETTING: San Borja-Arriarán Hospital, University of Chile, School of Medicine. PATIENT(s): Normally cycling healthy women and their partners. INTERVENTION(s): Structured interview before and during use of the contraceptive. MAIN OUTCOMES MEASURE(s): Sexual frequency, desire, and enjoyment; perception of health; and contraceptive satisfaction. RESULT(s): During the use of the implant more women reported irregular cycles (32% versus 11%) and vaginal spotting (38% versus 19%). Frequency of sexual relations was unchanged (2.3 versus 2.5/wk) but the percent of couples engaging in sexual relations during vaginal spotting increased (28% versus 11%). There was no significant difference in the percent of men or women who reported an increase, or decrease, in perceived sexual desire, sexual enjoyment, or perception of health during the use of Uniplant. CONCLUSION(s): Despite the alterations in menstrual cyclicity and the occurrence of spotting, the use of a contraceptive subdermal implant of nomegestrol acetate did not effect desire for, enjoyment of, or frequency of sexual relations in users.
    Fertility and Sterility 03/1997; 67(2):244-9. · 4.17 Impact Factor
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    ABSTRACT: OBJECTIVE: To evaluate a nomegestrol acetate subdermal contraceptive implant's (Uniplant; Thermex, Monaco) effect on the hypothalamus-pituitary-ovarian axis. DESIGN: A prospective clinical trial. SETTING: San Borja-Arriarán Clinical Hospital, University of Chile, School of Medicine. PATIENT(s): Normally cycling healthy women. INTERVENTION(s): Insertion of Uniplant. MAIN OUTCOME MEASURE(s): Luteinizing hormone pulse and endocrine profiles were assessed before, 48 hours after insertion, and after prolonged use of the implant. RESULT(s): Anovulation was noted in 100% of users in the first month. Seventy percent of subjects demonstrated follicular development with the absence of ovulation and an endocrine profile similar to the follicular phase: (LH pulse/8 hours 6.85 +/- 0.67, LH amplitude 3.54 +/- 0.65 mIU/mL (conversion factor to SI unit, 1.00), and E2 193 +/- 29.4 pg/mL (conversion factor to SI unit, 3.67), whereas 30% demonstrated no follicular activity with an endocrine profile similar to the luteal phase: (LH pulse/8 hours; 3.66 +/- 0.66, LH amplitude 5.76 +/- 1.73 mIU/mL, and E2 67.5 +/- 4 pg/mL. Clinical characteristics, serum gonadotropin concentration, and LH pulse characteristics failed to predict which subjects would initiate or remain devoid of follicular activity. CONCLUSION(s): Uniplant results in anovulation via two mechanisms: hypothalamic suppression in subjects who lack follicular development, and likely suppression of the pituitary LH surge in subjects who initiate follicular activity.
    Fertility and Sterility 03/1997; 67(2):250-5. · 4.17 Impact Factor
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Publication Stats

136 Citations
51.90 Total Impact Points

Institutions

  • 2007–2012
    • University of Santiago, Chile
      CiudadSantiago, Santiago, Chile
  • 2011
    • University of Chile
      • Departamento de Urología
      CiudadSantiago, Santiago, Chile