摘要:

Pre-eclampsia is a serious complication of the second half of human pregnancy which occurs at frequencies of 1 % to 5% in most parts of the world. It is characterized clinically by high blood pressure, proteinuria, and generalized edema in association with a wide range of pathophysiological organ and system disturbances. Untreated, it can lead to the occurrence of epileptic-like grand-mal convulsions (eclampsia), which is a source of considerable maternal and fetal morbidity. The disease is unusual in having no known cause, although an immunological impairment is suspected. Here we review the evidence that the condition is genetic in origin. Several genetic models are discussed. Markedly raised incidences are seen in blood relatives (mothers, daughters, sisters, and granddaughters) but not in relatives by marriage (daughters-in-law, mothers-in-law). This suggests that the condition is caused by maternal genes. Other evidence, however, implicates the fetal genotype. The most decisive data supporting this show a lack of concordance in monozygous twins. Thus the condition may be the result of a maternal-fetal genotype by genotype interaction, broadly analogous to Rhesus disease. To date, most attempts to find the genes involved have focused on the human leucocyte antigen (HLA) system. It is clear that the maternal genes are not in the HLA system, but the possibility that the postulated fetal genes are located there remains open. Current work concentrates on linkage studies aimed at finding the responsible genes. There is still a need for more pedigree and twin data, especially from non-European ethnic groups.

ISSN:1064-1955    

DOI:10.3109/10641959309031050

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Supplemental dietary calcium (2 gm/day) is recommended by some to prevent preeclampsia and premature labor. There are theoretical concerns, however, that such an approach may precipitate renal stone formation, since most gravidas are hypercalciuric, and their urine is supersaturated with calcium oxalate and phosphate salts. The present serial study of 8 healthy normotensive women at 4, 6, 8, 10, 12, 16, 20, 24, 28, 32, and 36+ weeks of pregnancy, and 12 weeks postpartum, was designed to assess the effects of gestation on urinary factors which inhibit stone formation. By gestational weeks 4 and 8, 24 hour creatinine clearances and calcium excretion, respectively, increased significantly, the former peaking by week 12, while the latter continued to rise and was 2.5-fold greater near term. Urinary inhibitor activity (14C oxalic acid incorporation into seed crystals) also increased significantly (27% near midpregnancy, remaining elevated till delivery). There was a striking increment of the glycoprotein crystallization inhibitor nephrocalcin, measured by a specific ELISA assay, which rose significantly by week 8, and was 20-fold higher near term. All values normalized 12 weeks postpartum. In other studies we determined that the amino acid composition and dissociation constant of nephrocalcin excreted in pregnancy was very similar to those of the glycoprotein inhibitor purified from the urine of nonpregnant adults. We conclude from these data that hypercalciuric gravidas with urine manifesting a high potential for crystallization are protected from stone formation, perhaps due to enhanced excretion of inhibitory proteins. Further studies are needed to ascertain if this protection is sufficient when the hypercalciuria is augmented by calcium loading.

ISSN:1064-1955    

DOI:10.3109/10641959309031051

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

To test whether factors other than angiotensin II (AII) are important in the control of aldosterone during pregnancy, we examined the inhibitory effects of dopamine upon aldosterone release during normal pregnancy in women with pregnancy-induced hypertension (PIH) and in normal age-matched nonpregnant women, using the dopamine antagonist metoclopramide.Plasma renin (PRC), plasma aldosterone (PAC), and serum Cortisol concentrations were measured before and 30 minutes after intravenous metoclopramide in 6 non-pregnant women during both phases of their menstrual cycle, 6 women taking oral contraceptive pills (OCPs) during both halves of their menstrual cycle, 6 normal third-trimester primigravidas and 9 women with PIH. AII were sodium replete and eating an adlibitum diet. Six pregnant and 6 non-pregnant women served as controls and had the same measurements before and after 2 ml intravenous saline instead of metoclopramide. Baseline PRC, PAC and Cortisol were higher in normal pregnant than non-pregnant women and PRC was reduced significantly from values for normal pregnancy in those with PIH. Serum Cortisol was elevated significantly in women taking OCPs compared with other non-pregnant women (P<0.05). PAC increased following metoclopramide in every subject, but PRC and Cortisol remained unchanged. PAC, PRC or Cortisol were not altered significantly over the same time period in control subjects. Although the percentage increment in PAC following metoclopramide was greater in women with PIH than in normal pregnant women (P<0.05), absolute changes were not significantly different between these two groups. Our findings demonstrate that dopamine exerts considerable inhibitory influence upon aldosterone release in both non-pregnant and pregnant women despite markedly elevated aldosterone concentration in pregnancy. This effect is apparent in both normotensive pregnant women and in those with PIH.

ISSN:1064-1955    

DOI:10.3109/10641959309031052

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Because of disagreement regarding the importance of maternal adrenal mineralocorticoid in gestational volume homeostasis and reproductive performance, we studied pregnant rats consuming standard or moderately sodium-restricted diets (22 or 2.2 mEq/100 gm), each subjected on gestational day 5 to SHAM surgery (SHAM) or adrenalectomy (ADNX), the latter combined with corticosterone replacement. Some animals were instrumented with chronic vascular catheters to measure plasma volume and mean arterial pressure (MAP) responses to captopril. We found that neither absolute plasma volume nor hematocrit was significantly altered by adrenalectomy in animals on either standard or sodium-restricted diets. However, Posmol, 9-10 mosmol/kg lower in SHAM pregnant than virgin controls, was 16-22 mosmol/kg below nonpregnant levels in ADNX dams. Despite this hypotonicity, plasma vasopressin (AVP) was not suppressed, suggesting hemodynamic stimulation of AVP secretion. Basal MAP was 105±3 mm Hg and 100±2 mm Hg in SHAM pregnant rats on normal and sodium-restricted diets, respectively, 114±2 mm Hg in SHAM operated virgins, and 87±4 mm Hg and 92±5 mm Hg in pregnant ADNX on standard and sodium-restricted diets, respectively. Following captopril, MAP decreased±5% in SHAM gravid and virgin rats, but declined±20% in ADNX dams, indicating that blood pressure was highly angiotensin II (Ang II) dependent. Plasma aldosterone was greater in SHAM pregnant rats on standard chow (50±13 ng/dl) than similarly treated virgins (27±17 ng/dl) (P<0.02), but levels were barely detectable in ADNX pregnant groups. Adrenalectomized dams on both standard and low-sodium chow had significantly (P<0.001) smaller litters (±4 pups) than did SHAM gravid animals on either diet (±8 pups). We conclude that mineralocorticoid of adrenal origin plays an important role in regulation of“effective”intravascular volume and reproductive performance during normal rat pregnancy. It also appears that insufficient fetal aldosterone enters the maternal circulation to maintain physiologic levels.

ISSN:1064-1955    

DOI:10.3109/10641959309031053

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Since the renal vasculature is vasodilated and the renal perfusion pressure (RPP) is reduced during pregnancy, the capacity to autoregulate renal blood flow (RBF) during pregnancy is unclear. Therefore, we assessed RBF auto-regulation in nonpregnant and pregnant sheep at RPP of 80, 75, 70, and 60 mmHg under control conditions, during amino acid infusion (SAP), and in sheep with nonfiltering kidneys in order to stress the normal feedback regulations of RBF. In nonpregnant animals, RBF was unchanged until RPP was reduced below 70 mmHg, but in pregnant animals the breakpoint occurred at 75-80 mmHg. The autoregulatory index (AI) was significantly higher in pregnant than in nonpregnant animals at all levels of RPP below 80 mmHg, indicating a greater impairment of RBF autoregulation during pregnancy. Amino acid infusion (SAP) elevated basal RBF similarly in all sheep and suppressed the autoregulatory curves of both groups, although to a greater extent in the pregnant sheep. Basal RBF was increased with nonfiltering kidneys in pregnant but not in nonpregnant animals. With nonfiltering kidneys, the levels of AI at 75, 70, and 60 mmHg were greater in pregnant compared with nonpregnant sheep, indicating a diminished residual autoregulatory capacity in the absence of the macula densa feedback mechanism (MDFM). In summary, ovine pregnancy is characterized by a reduced RBF autoregulatory capacity and by a reduced safety margin by which RPP can fall without reducing RBF.

ISSN:1064-1955    

DOI:10.3109/10641959309031054

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Adaptation of the maternal cardiovascular system to pregnancy is characterized by a reduction in vascular resistance and hypotension; by the third trimester, however, hypertension occurs in 5% of women. Nitric oxide (NO), synthesized from L-arginine by vascular endothelial cells, plays an important role in the control of systemic blood pressure. This study has assessed the relationship between NO synthesis and blood pressure in 12 normal pregnant and 13 hypertensive pregnant women. NO synthesis was determined as urinary nitrite (NO2−) and nitrate (NO3−) by chemiluminescence. Urinary NO2−excretion did not differ significantly between the hypertensive and normal women (median [range], 122 [68-324]and 147 [32-417] mmol/mmol creatinine, respectively; p0.05). After reduction of urinary NO3−to NO2−, urinary NOxexcretion (NO3−+ NO2−) was also similar in the hypertensive and normotensive women (38 [0.3-112] and 28 [5-63]mmol/mmol creatinine, respectively, P>0.05). However, a significant correlation was seen in the hypertensive women between the change in systolic blood pressure and urinary NOxexcretion (σd2= 98.5, n = 13, P<0.01). These findings suggest that a compensatory increase in the synthesis of NO may occur in hypertensive pregnant women in an attempt to maintain homeostasis.

ISSN:1064-1955    

DOI:10.3109/10641959309031055

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Virgin and pregnant rats were studied to determine whether blood pressure and/or renal hemodynamics are influenced by the vascular actions of arginine vasopressin (AVP) via the V1receptor. Blockade of the AVP-V1receptor with receptor antagonist d(CH2)5VDAVP in anesthetized, volume-depleted rats produced similar falls in blood pressure in both virgin and late-pregnant rats even though the late-pregnant rats already exhibited gestational hypotension. In the conscious, normovolemic condition, AVP-V1antagonism had no effect on blood pressure or renal hemodynamics in virgin or pregnant rats. These studies suggest that in nomal pregnancy the V1vascular receptor of AVP does not maintain blood pressure or renal function. When the animal is stressed, AVP-V1control of blood pressure is activated similarly in virgin and pregnant rats.

ISSN:1064-1955    

DOI:10.3109/10641959309031056

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

The effect of varying dietary protein intake from 16% to 35% (w/w) on glomerular binding of angiotensin II (AngII) has been studied in virgin and pregnant normotensive and spontaneously hypertensive rats. Although the higher protein diet caused an increase in AngII binding by glomeruli from both virgin and pregnant nomotensive rats a reduction was noted in virgin spontaneously hypertensive rats. These changes in binding were unassociated with any change in the binding affinity constant and unrelated to changes in blood pressure or plasma renin activity in any of the groups of rats studied. The protein-induced changes in glomerular AngII binding cannot explain the increase in glomerular plasma flow and glomerular filtration rate known to occur in response to an increase in protein intake.

ISSN:1064-1955    

DOI:10.3109/10641959309031057

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Serum and urinary levels of magnesium, sodium, potassium and calcium were determined in normotensive pregnant women and in women with pregnancy-induced hypertension (PIH) during the second and third trimester. No significant differences were evident in serum total magnesium between the two groups over the two trimesters. Serum total calcium, however, was significantly lower during the third trimester in women with pregnancy-induced hypertension. The 24-hour urinalysis revealed significant hypomagnesuria and hypocalciuria in women with PIH. Serum and urinary levels of sodium and potassium were not significantly different between the two groups. These observations suggest a disturbance in magnesium and calcium metabolism in women with PIH. It is uncertain if this is a consequence of raised blood pressure or, as suggested by a number of other studies, a cause of the disorder.

ISSN:1064-1955    

DOI:10.3109/10641959309031058

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor

摘要:

Pregnancy-induced hypertension (PIH) is a relatively common complication of pregnancy. In the present study we evaluated the role of Doppler ultrasound in the management of 36 patients with the disorder. Ultrasound assessment of amiotic fluid was performed on alternate days until parturition, as well as weekly ultrasound measurement of fetal abdominal circumference. Doppler analysis of maternal/fetal circulation was performed on alternate days until delivery. The Doppler indices were not revealed to the labor staff and were correlated with pregnancy outcome. Obstetric management was decided by the attending obstetricians by interpreting echographic features, fetal heart rate tracings, and/or deterioration of maternal condition. Our data show that in severe PIH, growth-retarded fetuses with absent or reversed diastolic flow in the umbilical artery are at higher risk for earlier delivery, decreased birth-weight, increased neonatal suffering, and perinatal mortality than those with flow throughout diastole.

ISSN:1064-1955    

DOI:10.3109/10641959309031059

出版商:Taylor&Francis    

年代:1993

数据来源: Taylor