Effect of renal denervation on renin gene expression, concentration, and secretion in mature ovine fetus.

To determine the role of the renal nerves on renin secretion and expression in the mature ovine fetus, we performed bilateral renal denervation on eight fetuses of time-dated pregnant ewes (126.8 +/- 0.6 days gestation) and compared renin in them to seven fetuses that underwent sham denervation (126.7 +/- 0.6 days gestation). Fetal arterial and venous catheters were implanted, and after 5-7 days of recovery isoproterenol was infused. Plasma active renin was lower in denervated animals than in intact animals under basal conditions and at each dose of isoproterenol. Plasma prorenin levels were lower in denervated fetuses but unaffected by isoproterenol. Denervation did not change renal renin, prorenin, or renin mRNA, but it did block isoproterenol-induced increases in renin mRNA in renocortical cells in vitro. We conclude that the renal nerves are required for renin secretory mechanisms and responsiveness of renin mRNA to beta-adrenergic stimulation but not for the expression of renin in the fetal kidney. We propose that one or more of the factors that maintain renin expression in the perinatal period may be absent or may be replaced by the renal nerves in the adult.

Maturation of cortisol responses to adrenocorticotropic hormone in twin fetal sheep in vivo.

OBJECTIVE: Adrenal steroidogenesis is important for maturation of fetal organ systems and plays a role in triggering parturition in ovine pregnancies. Studies have suggested a differential increase in baseline cortisol between twin gestations near term. Our aim was to further delineate the mechanisms responsible for the differences between the hypothalamic-pituitary-adrenal axes of twin fetuses in vivo. STUDY DESIGN: Surgery was performed on pregnant ewes (n = 6) with twin gestations to implant fetal vascular catheters. After recovery but while the subjects were resting, plasma cortisol concentrations were similar in both fetuses. Fetuses received, intravenously, boluses of adrenocorticotropic hormone at 2 doses, and plasma samples were obtained for analysis of the cortisol response. This stimulation by adrenocorticotropic hormone was then repeated in the same fetuses approximately 4 days later, after the increase of resting daily cortisol values in one but not the other fetus. RESULTS: Cortisol responses to adrenocorticotropic hormone before changes in daily resting cortisol concentrations were indistinguishable between twins. However, after separation of daily resting cortisol values, fetuses in group A (elevated resting cortisol concentration) demonstrated a significantly increased response to stimulation by adrenocorticotropic hormone. CONCLUSION: These results suggest a differential development in response to stimulation by adrenocorticotropic hormone between twin fetuses in vivo as the mechanism responsible for the asynchronous elevation of one twin's resting plasma cortisol concentration.

Clinical consequences of antiphospholipid antibodies: an historic cohort study.

OBJECTIVE: To determine the risk of antiphospholipid antibody-related disorders in women with elevated levels of these antibodies. METHODS: We used an historic cohort study design. Surveys of medical and obstetric histories for the interval from initial antibody testing to the time of patient interview were used to calculate age-adjusted rates for the development of medical disorders associated with antiphospholipid antibodies. The cohort included 130 women with lupus anticoagulant, medium to high levels of immunoglobulin G anticardiolipin antibodies, or both. RESULTS: The median interval of study was 3.2 years (range 0.7-9.5, mean 3.7). Sixty-three subjects (48%) developed at least one new disorder during the study interval. The age-adjusted rates (per 1000 patient-years; +/- standard error) for the development of the disorders studied were as follows: thrombosis (156.8 +/- 30.0), cerebrovascular accident (93.8 +/- 25.1), amaurosis fugax (57.1 +/- 23.2), transient ischemic attack (170.4 +/- 27.6), systemic lupus erythematosus (9.8 +/- 3.8), and autoimmune thrombocytopenia (56.0 +/- 22.2). Of the 34 thrombotic events that occurred during the study interval, eight were associated with pregnancy and eight occurred while the patients were taking anticoagulant medications. CONCLUSIONS: Our subjects developed complications associated with antiphospholipid antibodies at a substantial rate, and almost half suffered at least one new event during the study interval. The high rate of thrombosis in individuals with antiphospholipid antibodies, especially associated with pregnancy, underscores the need to evaluate long-term anticoagulation in these patients.

Unexplained elevations of maternal serum alpha-fetoprotein in women with antiphospholipid antibodies: a harbinger of fetal death.

OBJECTIVE: To determine whether unexplained elevations of maternal serum alpha-fetoprotein (MSAFP) in women with antiphospholipid antibodies are associated with adverse pregnancy outcomes. METHODS: A retrospective cohort study was used to compare pregnancy outcomes between women with second-trimester MSAFP values equal to or greater than 2.5 multiples of the median (MoM) and less than 2.5 MoM. The cohort included 60 pregnancies in 47 women with medium to high positive levels of immunoglobulin (Ig) G anticardiolipin antibodies, lupus anticoagulant, or both. RESULTS: Thirteen pregnancies (22%) had elevated MSAFP values (median 3.6 MoM, range 2.5-12.6). Of these, amniotic fluid AFP was normal in seven and elevated in one. None of the elevated MSAFP levels were explained by fetal anomalies, current fetal death, multiple gestation, incorrect dates, or vaginal bleeding. Pregnancies with elevated MSAFP values had a significantly higher incidence of fetal death (eight of 13, 62%, versus three of 47, 6%) and perinatal loss (ten of 13, 77%, versus seven of 47, 15%) than those with normal MSAFP (P < .001, Fisher exact test). In these women, the sensitivity and specificity of an unexplained elevated MSAFP level in ascertaining fetal death were 73 and 90%, respectively. For perinatal loss, the sensitivity was 59% and the specificity was 93%. Of the placentas studied, infarction occurred in eight of nine (89%) among the women with elevated MSAFP. CONCLUSIONS: Unexplained second-trimester elevations of MSAFP are common in women with antiphospholipid antibodies and are significantly associated with fetal loss. Abnormalities in the fetoplacental barrier are implicated as part of the pathophysiology of antiphospholipid antibody-mediated pregnancy loss.