Browsing by Author "MENA, P"

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    EFFECT OF MATERNAL ADMINISTRATION OF THYROTROPIN-RELEASING-HORMONE ON THE PRETERM FETAL PITUITARY-THYROID AXIS
    (1991) MAYA, F; MENA, P; FORADORI, A; BECERRA, M; INZUNZA, A; GERMAIN, A
    We evaluated the response of preterm fetuses to maternal intravenous injection of 400-mu-g of thyrotropin releasing hormone (TRH) between 30 minutes and 5 hours before delivery (n = 12). An additional seven mothers received saline solution and served as control subjects. There were no statistically significant differences in gestational age, birth weight, or Apgar scores between groups. At delivery, concentrations of maternal thyrotropin were elevated in the TRH group compared with the control group (12.0 +/- 1.6 vs 5.6 +/- 0.5 mU/L; p < 0.005); however, maternal triiodothyronine (T3) values remained unchanged. Significant elevations of fetal thyrotropin and T3 were observed after maternal administration of TRH compared with control subjects (45.8 +/- 7.7 vs 8.4 +/- 0.9 mU/L (p < 0.002) and 1.3 +/- 0.07 vs 0.7 +/- 0.04 nmol/L or 87 +/- 5 vs 49 +/- 3 ng/dl (p < 0.001), respectively). Fetal thyroxine (T4) and prolactin values were also elevated after exposure to TRH (135 +/- 5 vs 86 +/- 10 nmol/L or 10.5 +/- 0.4 vs 6.7 +/- 0.8-mu-g/dl (p < 0.001) and 212 +/- 31 vs 105 +/- 28-mu-g/L (p < 0.05), respectively). Two hours after birth, a significant increase in T3 but not T4 levels was observed in both groups of infants. These data indicate that fetal exposure to a single dose of TRH via maternal administration of this hormone results in marked stimulation of the preterm fetal pituitary-thyroid axis, as in the fetus at term, and that this treatment does not inhibit the early postnatal surge of T3.
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    RESPONSE OF THE MATERNAL, FETAL, AND NEONATAL PITUITARY-THYROID AXIS TO THYROTROPIN-RELEASING-HORMONE
    (1986) MOYA, F; MENA, P; HEUSSER, F; FORADORI, A; PAIVA, E; YAZIGI, R; MICHAUD, P; GROSS, I
    Thyrotropin releasing hormone (TRH) readily crosses the placenta and stimulates the fetal pituitary. We studied the response of the maternal and fetal pituitary-thyroid axes to TRH and the influence of prenatal exposure to TRH on the physiological postnatal increase in thyrotropin (TSH) and triiodothyronine (T3) in the neonate. Twenty-six pregnant women received TRH (400 or 600 .mu.g) intravenous or saline (controls) either 2 or 12 h before elective cesarean section at term. Administration of 400 .mu.g of TRH resulted in significant elevations of maternal TSH (15.7 .+-. 2.9 versus 3.2 .+-. 0.4 .mu.U/ml, p < 0.01) and prolactin (416 .+-. 94 versus 223 .+-. 41 ng/ml, p < 0.05) 2 h later. Maternal T3 remained unchanged. A higher dose of TRH (600 .mu.g) produced comparable results. Maternal administration of TRH (400 .mu.g) 2 h before delivery resulted in significant increases in fetal TSH and T3 over controls (21.1 .+-. 3.7 versus 4.8 .+-. 1.0 .mu.U/ml, and 132 .+-. 12 versus 64 .+-. 9 ng/dl, p < 0.01, respectively). Cord blood hormone levels 12 hours after TRH administration were similar to controls. Higher doses of TRH did not produce further increases in fetal TSH or T3. Control and treated neonates demonstrated similar physiological postnatal increases in TSH and T3, suggesting that prior exposure to TRH did not blunt this response. These data suggest that maternal administration of TRH is an effective way of increasing fetal T3 levels, and that this treatment does not inhibit the postnatal surge is TSH and T3.
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    TIMING OF CONCEPTION AND THE RISK OF SPONTANEOUS-ABORTION AMONG PREGNANCIES OCCURRING DURING THE USE OF NATURAL FAMILY-PLANNING
    (1995) GRAY, RH; SIMPSON, JL; KAMBIC, RT; QUEENAN, JT; MENA, P; PEREZ, A; BARBATO, M
    OBJECTIVE: Our purpose was to ascertain the effects of timing of conception on the risk of spontaneous abortion.