Browsing by Author "CROXATTO, HB"
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- Item7-CELL HUMAN EGG RECOVERED FROM OVIDUCT(1975) AVENDANO, S; CROXATTO, HD; PEREDA, J; CROXATTO, HB
- ItemA STUDY ON THE FEASIBILITY OF SUPPRESSING OVARIAN ACTIVITY FOLLOWING THE END OF POSTPARTUM AMENORRHEA BY INCREASING THE FREQUENCY OF SUCKLING(1988) DIAZ, S; MIRANDA, P; BRANDEIS, A; CARDENAS, H; CROXATTO, HBThe aim of the study was to test the effect of increasing the frequency of breastfeeding upon ovarian function following the end of postpartum amenorrhoea. Women exclusively breastfeeding (n = 14) who experienced their first postpartum menstruation between the third and fifth month after delivery were randomly allocated to an experimental (n = 7) and a control (n = 7) group and studied during the next two cycles. Women in the experimental group agreed to increase the number of breastfeeding episodes per day throughout the second cycle. Blood samples were drawn twice a week from the first to the third postpartum menstruation for prolactin, oestradiol and progesterone determinations. The number of breastfeeding episodes per day and night and the length of each episode were recorded daily. An average frequency of 11 nursing episodes per 24 h was reported during the first study cycle in both groups. The experimental group increased by 50% of the breastfeeding frequency after the second menstruation while the control group kept its spontaneous feeding pattern. The increase of suckling frequency occurred mainly during day hours. The total breastfeeding time per 24 h was not increased. The length of the menstrual cycle was not altered by the increased suckling frequency. The endocrine pattern differed neither between the first and second cycle of the experimental group nor between the experimental and control group, with the exception of PRL levels which were higher in the experimental gorup throughout both cycles. Twenty cycles (71%) showed progesterone values compatible with ovulation (> 9.5 nmol/l). The highest progesterone values and the highest oestradiol values observed in the ovulatory cycles of lactating women were within the range found in non-nursing fertile women. Plasma levels of PRL were significantly elevated in all cycles but one, in comparison with PRL levels in non-nursing women. It is concluded that if cyclic ovarian function is reestablished early in fully nursing women, a mere increase in the number of breastfeeding episodes, without augmenting total suckling time and the frequency of nocturnal episodes, does not provide a sufficient stimulus to resuppress the pituitary-ovarian axis.
- ItemADDITIVE EFFECT OF RU-486 AND ANORDRIN ON PREGNANCY INTERRUPTION IN THE MOUSE(1993) FORCELLEDO, ML; CARDENAS, H; CROXATTO, HBThe effect of various doses of anordrin and RU 486, alone or combined, on serum progesterone (P) levels, fetal resorption, and recovery of ovulation was studied in mice. Each drug was given as a single sc injection on day 7 of pregnancy and autopsy was performed on days 8, 9, or 11. Serum P was normal at 24 h but fell significantly 48 h after treatment with anordrin (0.05 mg). Doses of 0.05 or 0.2 mg anordrin were effective in interrupting pregnancy in 30% and 70% of pregnant mice, respectively. RU 486, 0.01 mg per mouse, induced a pronounced decrease of P levels 24 h after treatment and interrupted pregnancy in 50% of pregnant mice. The combined treatment with submaximal doses of anordrin plus RU 486 did not further decrease P levels, but increased the proportion of mice with fetal resorptions to 90%. The combination of small doses of anordrin with RU 486 had an additive effect on pregnancy termination. The additive effect required a dose of RU 486 above the threshold level. Direct observation of aborted fetuses indicated that the resorptive process occurred earlier with RU 486 than with anordrin. Recovery of ovulation was associated with pregnancy termination in a high proportion of mice treated with either drug or their combination.
- ItemADNEXAL COMPLICATIONS IN WOMEN UNDER TREATMENT WITH PROGESTOGEN IMPLANTS(1975) CROXATTO, HD; DIAZ, S; ROSATI, S; CROXATTO, HB
- ItemATTEMPTS TO MODIFY OVUM TRANSPORT IN WOMEN(1979) CROXATTO, HB; ORTIZ, ME; DIAZ, S; HESS, R
- ItemATTEMPTS TO PROGRAM OVULATION WITH EXOGENOUS ESTROGENS AND LH-RH ANALOGUE(1975) ZANARTU, J; ROSNER, JM; GUILOFF, E; IBARRAPOLO, AA; CROXATTO, HD; CROXATTO, HB; AGUILERA, E; COY, DH; SCHALLY, AV
- ItemCHANGES IN SERUM LEVELS OF SHBG, ENDOGENOUS LIGANDS AND LEVONORGESTREL INDUCED BY ETHINYLESTRADIOL IN NORPLANT USERS(1992) NOE, G; PAVEZ, M; CROXATTO, HBThis work was done in search for a model to examine target organ response to fluctuations in serum levels of sex hormone-binding globulin (SHBG) and its ligands. The time course and magnitude of fluctuations of SHBG, levonorgestrel (L-Ng), estradiol (E2), testosterone (T) and dihydrotestosterone (DHT) in serum were examined during and after treatment with 50 ug of ethinylestradiol (EE2) daily for 10 days in 10 volunteer women using NORPLANT(R) implants. Six of these volunteers were also treated with 20 ug of EE2 daily for 7 days and two additional volunteers using a copper-T IUD were treated with 50 ug of EE2 daily for 7 days. In all cases, SHBG and L-Ng levels increased in a close parallel manner several-fold above basal levels during treatment, reaching a maximum around two days after the last EE2 pill. In contrast, the levels of E2 and T increased in one subject, decreased in 5 and remained unchanged in 4, while changes of DHT were unrelated to those of the other ligands.
- ItemCIRCADIAN VARIATION OF BASAL PLASMA PROLACTIN, PROLACTIN RESPONSE TO SUCKLING, AND LENGTH OF AMENORRHEA IN NURSING WOMEN(1989) DIAZ, S; SERONFERRE, M; CARDENAS, H; SCHIAPPACASSE, V; BRANDEIS, A; CROXATTO, HBThe circadian pattern of plasma PRL levels and the PRL response to suckling were examined at various times during the first postpartum year and related to the length of lactational amenorrhea. Ten healthy women whose infants were breast-fed exclusively and who were amenorrheic 3 months postpartum were studied 3, 6, and 9-11 months postpartum. The women and their babies were admitted to a metabolic unit for 48 h. On the second day, blood samples were drawn at 2-h intervals for 26 h starting at 0800 h and also 10 and 30 min after the initiation of six of the nursing episodes. During the three postpartum periods, there was a circadian rhythm of basal plasma PRL concentrations; the peak concentrations occurred between 2400-0600 h. Suckling induced a significant rise in plasma PRL levels at all hours except 0800 h. There was a positive correlation between the duration of the nursing episode and the suckling-induced PRL increase at 30 min. Both the basal plasma PRL levels and the PRL responses to suckling diminished with time after delivery. This trend was less evident at 0400 h and was not fully explained by changes in the nursing pattern. The five women in whom menstrual cycles resumed before day 180 postpartum had lower basal and suckling-induced plasma PRL levels than in the women who had amenorrhea for a longer period. This difference was present in the third month, when all women were amenorrheic and fully nursing and when the frequency and duration of nursing episodes and infant growth rates were similar. The results indicate that comparable nursing patterns may be associated with different plasma PRL levels, which are associated with different lengths of lactational amenorrhea. An early difference in the sensitivity of the breast-hypothalamus-pituitary system to suckling may explain the differences in the duration of lactational amenorrhea, which are not dependent on the breastfeeding pattern. The magnitude of the PRL response to suckling may predict the likelihood of recovering ovarian function during lactation.
- ItemCLINICAL-ASSESSMENT OF SUBDERMAL IMPLANTS OF MEGESTROL ACETATE, D-NORGESTREL, AND NORETHINDRONE AS A LONGTERM CONTRACEPTIVE IN WOMEN(1975) CROXATTO, HB; DIAZ, S; QUINTEROS, E; SIMONETI, L; KAPLAN, E; RENCORET, R; LEIXELARD, P; MARTINEZ, CMegestrol acetate (MA), d-norgestrel (d-Ng) and norethindrone (NET) contained in Silastic capsules were implanted under the skin for clinical evaluation as a long-term contraceptive in women. Woman-mo. [1509] of exposure and 4 pregnancies were recorded within the first 12 mo. of use in 135 women who received 6 MA implants. Woman-mo. [1049] and 19 pregnancies were recorded within the first 12 mo. of use in 131 women who received 4 d-Ng implants. After 12 mo. use, the implants were replaced with a new set of capsules. The contraceptive effectiveness of the 2nd and subsequent set of implants was similar to that of the 1st. Five NET implants failed completely to prevent pregnancy and 4 MA implants combined with 2 d-Ng implants were as effective as 6 MA implants. Other doses tested were 5 MA, 3 d-Ng and 4 MA plus 1 d-Ng. They were significantly less effective than the higher doses. No adverse effect upon the outcome of unplanned pregnancies was noted and prompt recovery of fertility was observed after termination of treatment. Ovulation took place in most cycles of women treated with 5 or 6 MA implants, as judged from the occurrence of LH [luteinizing hormone] peak in urine, pregnanediol excretion, changes of cervical mucus, BBT [basal body temperature], and endometrial biopsy. Intermenstrual bleeding was by far the most common side effect recorded. Initially, it occurred in about 30% of the cycles, but the incidence decreased gradually and by the end of the 2nd yr, it was below 10%. Adnexal complications were observed in some of the treatment groups.
- ItemCORRELATION BETWEEN HISTOLOGIC DATING OF HUMAN CORPUS-LUTEUM AND THE LUTEINIZING-HORMONE PEAK-BIOPSY INTERVAL(1980) CROXATTO, HD; ORTIZ, ME; CROXATTO, HBThe accuracy of retrospective dating of ovulation in women based on the histologic dating of the corpus luteum was assessed. Corpora lutea enucleated from the ovary of 39 women from 1-6 days following the luteinizing hormone [LH] peak in plasma were examined by routine histologic techniques and dated according to Corner''s criteria. The correlation between the LH peak-biopsy interval and histologic dating was assessed. Linear regression analysis of the data gave a correlation coefficient of 0.76. The dating of different corpora lutea obtained at the same LH peak-biopsy interval can differ by as much as 4 days. The stages named by Corner as days 1 and 2 seem to develop within the first 24 h following the LH peak, while stages corresponding to days 4 and 5 each take 2 days to develop. The use of corpus luteum morphologic features for retrospective timing of ovulation is evidently subject to an error of variable magnitude due to unequal duration of each stage, and considerable individual variation.
- ItemDIFFERENTIAL TRANSPORT OF FERTILIZED AND UNFERTILIZED OVA IN PSEUDOPREGNANT RATS(SOC BIOL CHILE, 1979) VILLALON, M; ORTIZ, ME; AGUAYO, C; MUNOZ, J; CROXATTO, HB
- ItemDIFFERENTIAL TRANSPORT OF FERTILIZED AND UNFERTILIZED OVA IN THE RAT(SOC STUDY REPRODUCTION, 1982) VILLALON, M; ORTIZ, ME; AGUAYO, C; MUNOZ, J; CROXATTO, HB
- ItemEFFECT OF ESTRADIOL 3-BENZOATE AND ESTRADIOL 3,17BETA ON OVUM TRANSPORT IN RATS(ASSN LATINOAMER CIENC FISIOL, 1975) ORTIZ, ME; VILLALON, M; ALONSO, ML; CROXATTO, HB
- ItemEFFECTIVENESS OF DIFFERENT ESTROGEN PULSES IN PLASMA FOR ACCELERATING OVUM TRANSPORT AND THEIR RELATION TO ESTRADIOL LEVELS IN THE RAT OVIDUCT(1986) FORCELLEDO, ML; DELACERDA, ML; CROXATTO, HBElevations of circulating estradiol (E2) levels due to administration of exogenous E2 accelerate embryo transport through the genital tract in pregnant rats. This study relates oviductal embryo transport to tissue E2 levels associated with blood E2 oscillations of differing profiles. Plasma E2 pulses differing in rate of increase, amplitude, and duration were achieved through various schedules of iv and sc E2 administration. Rats on the first day of pregnancy received a total dose of 5 .mu.g 17.beta.-E2 by short (10-15 min) or long (200-300 min) term iv infusions. Some animals were used to monitor blood and tissue levels of E2 (oviduct and diaphragm). Others were killed 24 h after treatment to assess number of embryos recovered. Fast iv infusions caused brief, high amplitude (> 1000 pg/ml) E2 oscillations which were ineffective in eliciting accelerated embryo transport. The longer iv infusions produced lower but sustained elevations of circulating E2 levels comparable to those achieved by sc administration and were associated with accelerated embryo transport. The oviductal E2 concentration during and after a short iv infusion was never lower than that associated with a sc injection. The lack of response to a brief, high amplitude increase in circulating E2, therefore, could not be accounted for by decreased tissue content of the hormone. These results indicate that when the total mass of E2 administered is kept constant, the magnitude of embryo transport acceleration is positively correlated with the duration and negatively correlated with the amplitude and/or slope of increase in circulating estrogen. Since different tissue content of E2 does not account for the response or no response observed it follows that the geometry of E2 oscillations in plasma has a signal value for the target cells which acts independently from the bioavailability of the hormone.
- ItemEFFECTS OF DELAYED TRANSFER AND TREATMENT WITH ESTROGEN ON THE TRANSPORT OF MICROSPHERES BY THE RAT OVIDUCT(1988) MOORE, GD; CROXATTO, HBStarch or dextran blue microspheres were transferred microsurgically to the influndibulum of the oviduct on Days 1, 2, or 3 of pregnancy of control and oestradiol-treated rats. The animals were killed a few hours to several days after transfer to assess the number and distribution of ova and microspheres in the tract. After transfer on Day 1 of pregnancy, microspheres and eggs crossed the ampullary-isthmic junction (AIJ) 18 h after ovulation. After transfer on Day 2 of pregnancy, more than 50% of microspheres were retained in the ampulla, indicating that the AIJ changes again 34 h after ovulation. Treatment with oestradiol did not advance the passage of eggs or microspheres across the AIJ but caused accelerated transport through the isthmus as soon as the eggs or microspheres reached this segment. Dextran blue microspheres were seen to move back and forth in the isthmus of control anaesthetized rats at a frequency of 5-6 times/min. Between 7 and 20 h after treatment with oestradiol the frequency of these movements was significantly augmented, indicating that increased frequency of contractions of the smooth muscle of the isthmus precedes and accompanies accelerated transport of ova through this segment.
- ItemEFFECTS OF RU486 ON THE OVARIAN RESPONSE OF IMMATURE RATS TO PREGNANT MARES SERUM GONADOTROPIN OR DIETHYLSTILBESTROL(1994) FORCELLEDO, ML; LEIVA, L; CROXATTO, HBThe purpose of this study was to further investigate the role of progesterone in follicular development induced by pregnant mare serum gonadotrophin (PMSG) or diethylstilbestrol (DES), in pre-pubertal rats, using RU486 to prevent the receptor-mediated actions of progesterone. Intact or hypophysectomized 26-day-old rats received either a single injection of 10 IU PMSG i.p., or 2 mg DES s.c. daily for 3 days, with or without 0.8 mg RU486 s.c. daily for 3 days. Groups of rats were killed 51-96 h after the first injection. RU486 significantly increased the ovarian weight gain, the ovarian and circulating concentrations of progesterone, the concentrations of immunoreactive and bioactive LH and the number of ovulated oocytes in intact rats. RU486 did not affect the ovarian weight increase induced by PMSG or the ovulatory response following PMSG plus human chorionic gonadotrophin (HCG) in rats hypophysectomized 24 h before initiating treatment or in intact rats where ovulation was blocked with chlorpromazine. The ovarian weight gain, the development of antral follicles and the increments in tissue and plasma progesterone concentrations and luteinizing hormone (LH) plasma concentrations elicited by DES in intact rats, were further increased by concomitant treatment with RU486, whereas the ovarian weight increase and antral follicle development induced by DES were completely inhibited by RU486 in hypophysectomized rats. Follicles stimulated to grow by DES plus RU486, but not by DES alone, were capable of ovulating in response to HCG. These results show that ovarian growth and follicular development induced by exogenous gonadotrophin or oestrogen in the immature rat are enhanced by RU486 and that this synergistic effect of the progesterone receptor blocker is either pituitary-mediated or requires the permissive action of a pituitary factor. Overall they support a negative effect of progesterone on follicular development in the rat.
- ItemEGG TRANSPORT IN FALLOPIAN-TUBE(1975) CROXATTO, HB; ORTIZ, MES
- ItemEMBRYOS OF DIFFERENT AGES TRANSFERRED TO THE RAT OVIDUCT ENTER THE UTERUS AT DIFFERENT TIMES(1989) ORTIZ, ME; LLADOS, C; CROXATTO, HBIndirect evidence of embryo signalling to the oviduct was sought in rats by examining the transport of embryos of different ages. One-cell or four-cell embryos were transferred to the oviducts of recipient rats on Day 1 of pregnancy, and the number, condition, and location of native and transferred embryos was assessed on Day 4. To control for effect of the presence of foreign embryos and excess number of eggs and the transfer procedure upon the fate of native embryos, other groups of rats were sham-operated or left undistributed. Recipients had a mean number of ova significantly higher than controls. In controls and recipients of 1-cell embryos, the majority of eggs reached the morula stage and all of them were located in the oviducts. In those animals receiving 4-cell embryos, half of the eggs had reached the blastocyst stage and 28% were in the uteri (p < 0.005). These results support the idea that advanced embryos can influence the timing of their entrace to the uterus in rats.
- ItemENDOCRINE RESPONSE AND OVUM TRANSPORT IN WOMEN TREATED WITH D-TRP6-LUTEINIZING HORMONE-RELEASING HORMONE IN THE POST-OVULATORY PERIOD(1982) GUILOFF, E; SALVATIERRA, AM; ORTIZ, ME; CROXATTO, HBPossible alterations in ovum transport during increased activity of the hypothalamic-pituitary-ovarian axis were investigated in women. D-Trp6-LHRH, a synthetic peptide with potent gonadotropin-releasing activity, was used to induce a gonadotropin surge and stimulate ovarian steroid secretion in the postovulatory phase. The compound was administered i.m. or i.v. 24, 48 or 72 h following the maximum preovulatory lutropin level in plasma in 7 women. An immediate and pronounced gonadotropin surge accompanied by a moderate increase in the estradiol and progesterone level was obtained in all cases. Ova were recovered from the fallopian tubes in 4 of the 7 women 24 h following treatment. The rate of recovery and the location of ova within the genital tract indicate that the treatment and the resulting endocrine changes failed to accelerate migration of the ova toward the uterus. In comparison with other mammals transport of the ovum in the woman is relatively insensitive to endocrine changes occurring in the postovulatory phase.
- ItemESTROGEN AND PROGESTERONE RECEPTORS IN THE OVIDUCT DURING EGG TRANSPORT IN CYCLIC AND PREGNANT RATS(1988) FUENTEALBA, B; NIETO, M; CROXATTO, HBWe investigated the temporal relationships between ovum transport and changes in the concentration of nuclear steroid receptors in the oviduct of cyclic and pregnant rats. A lack of parallelism between estrogen and progesterone fluctuations in plasma and their respective nuclear receptor concentrations in the oviduct predominated during egg transport. In pregnant animals, oviductal egg transport took 24 h longer than in nonpregnant animals. In both conditions, transport was initiated while the action of estrogen and progesterone on the oviduct.sbd.measured as nuclear receptor accumulation.sbd.was decreasing. Three or four days later, depending on whether the animal was pregnant, the eggs entered the uterus shortly after an increase in the nuclear receptor accumulation of both hormones. Treatment with RU486, a progesterone receptor-blocking agent known to cause premature arrival of eggs in the uterus, advanced estrogen receptor accumulation in the oviduct of pregnant rats. These data suggest that the arrival of eggs in the uterus is timed by a transitory increase in nuclear estrogen receptor in the oviduct that does not necessarily reflect a similar change of circulating estradiol. Moreover, in pregnant rats, the onset of this estrogenic action is delayed by a progesterone receptor-mediated effect that hinders nuclear estrogen receptor accumulation.