Noriyoshi Kawasaki

Effect of calcium supplementation on the vascular sensitivity to angiotensin II in pregnant women

Pregnant women destined to develop pregnancy-induced hypertension lose refractoriness to the pressor effects of infused angiotensin II. The effect of calcium supplementation on the vascular sensitivity to angiotensin II was investigated in pregnant women. We administered orally 600 mg of calcium L-aspartate daily to 22 pregnant women from 20 weeks of gestation to delivery. The values for the effective pressor dose of angiotensin II in the calcium-supplemented women were compared with those in 72 nonsupplemented pregnant women. The vascular sensitivity was significantly decreased after calcium supplementation. The values for the effective pressor dose of angiotensin II in the calcium-supplemented patients were 18.1 +/- 1.2 ng/kg/min at 20 weeks of gestation, 32.2 +/- 2.6 ng/kg/min at the twenty-sixth week, 41.1 +/- 3.4 ng/kg/min at the thirtieth week, and 25.9 +/- 2.9 ng/kg/min at the thirty-sixth week (mean +/- SEM), while those in the nonsupplemented patients were 17.3 +/- 1.2, 17.7 +/- 1.6, 17.6 +/- 1.2, and 15.0 +/- 1.6 ng/kg/min, respectively. Assessment of the changes in the effective pressor dose of angiotensin II in the individual patients indicated that the percentile changes from 20 weeks of gestation in the calcium-supplemented patients were also significantly greater than those in 22 nonsupplemented patients. These findings suggest that calcium supplementation tends to reduce the vascular sensitivity in pregnancy. The present dosage of calcium did not affect the blood chemical parameters and did not reduce the blood pressure. The incidence of pregnancy-induced hypertension in the calcium-supplemented patients was 4.5%, which was smaller than that (21.2%) in the nonsupplemented patients. Although there is no clear explanation of the mechanisms involved in such an effect of calcium, the present results do provide evidence to support the idea that oral calcium intake can prevent the onset of pregnancy-induced hypertension.

Effects of pregnancy and hormone treatments on pressor response to angiotensin II in conscious rats.

Pressor responses to graded doses of angiotensin II in conscious rats were significantly reduced on days 13 and 19 of pregnancy compared with those in nonpregnant rats. To study the hormonal regulation of this altered pressor response to angiotensin II during pregnancy, we administered estradiol, progesterone, and human chorionic gonadotropin to nonpregnant rats. In ovariectomized rats no effect of estradiol on the pressor response to angiotensin II was found, but injections of progesterone with or without estradiol pretreatment significantly reduced the pressor response to angiotensin II. In intact rats human chorionic gonadotropin induced elevation of endogenous progesterone levels, followed by a significant decrease in the pressor response to angiotensin II. Injection of estradiol after human chorionic gonadotropin pretreatment produced a significant elevation in the pressor response to angiotensin II. These findings indicate that the decrease in angiotensin pressor response in pregnant rats is mediated mainly by progesterone rather than by estrogen.

A diminished intrapartum amniotic fluid index is a predictive marker of possible adverse neonatal outcome when associated with prolonged labor.

Objective: To determine whether a diminished intrapartum amniotic fluid volume represents a risk of adverse neonatal outcome when it occurs in conjunction with prolonged labor. Methods: The intrapartum amniotic fluid index (iAFI) was measured in 242 parturients over 35 weeks of gestation during 1st-stage labor, and the umbilical artery blood gas was analyzed at delivery. The subjects were divided into group A (n = 99), having a diminished amniotic fluid volume (iAFI ≤8.0 cm) and group B (n = 143), having a normal amniotic fluid volume (iAFI 8.1–20.0 cm), and selected antenatal, delivery, and neonatal variables were compared. In addition, the two groups were subdivided according to the duration of labor. Statistical analysis was performed using independent Student’s t test, Mann-Whitney U test, chi-square analysis, and Fisher’s exact test where appropriate. p < 0.05 was considered significant. Results: The patient characteristics and pregnancy outcomes were similar in groups A and B, as were the incidences of an umbilical artery blood pH <7.20 and/or an Apgar score <7 (group A 9.5%, group B 10.1%). In group A, however, the incidence of an adverse neonatal outcome was 23.5% in cases in whom the duration of labor was longer than 8 h which was significantly higher than in cases in whom the duration of labor was 8 h or less (2.8%; p < 0.01). In group B, the incidence of an adverse neonatal outcome was similar in the two subgroups. Conclusions: The risk of an adverse neonatal outcome is higher in patients with diminished amniotic fluid volume if labor is prolonged. Consequently, determination of the iAFI could be a useful admission test.

Effects of Pregnancy and Estrogen on the Angiotensin II Pressor Response of the Rabbit Using Serial Systolic Blood Pressure Measurement in the Ear

Serial systolic blood pressure measurements were made in order to assess the effects of pregnancy and estrogen on the angiotensin II pressor response of the rabbit. The systolic blood pressure of the ear in 5 pregnant rabbits did not change throughout the gestational period, being compatible with that in 14 nonpregnant rabbits. However, vascular resistance to infused angiotensin II (over 13.1 ng/kg/min required to elicit a pressor response of 20 mmHg in systolic pressure) was demonstrated as early as the 10th day of pregnancy, and maximum mean resistance occurred on the 20th day: the mean pressor dose required was 34.5 ± 3.6 ng/kg/min (mean ± S.D.). In a separate series, vascular resistance in castrated rabbits was demonstrated as early as the 10th day of estrogen administration, reached a maximum at the 4th week, and then gradually decreased to the control level (pretreatment, 10.5 ± 2.5 ng/kg/min; 10 days, 18.9 ± 2.3 ng/kg/min; 4 weeks, 32.4 ± 5.4 ng/kg/min; 10 weeks, 18.3 ± 3.6 ng/kg/min; and 24 weeks,...

Fatal heart monitoring and ultrasound in the management of placental abruption

Three cases of placental abruption with the “pseudosinusoidal” fetal heart rate (FHR) pattern, a periodic late deceleration related to frequent uterine contractions are reported. This ‘pseudosinusoidal’ pattern is clearly not a true sinusoidal pattern. The fetal monitoring patterns of these patients are presented and discussed along with the use of ultrasound in the management of this condition. All infants were delivered by cesarean section with low Apgar scores at birth, but they soon recovered completely.

Case report of dysgerminoma in a patient with 46,XX pure gonadal dysgenesis

A clinicopathological study of a 42-year-old female with pure gonadal dysgenesis and dysgerminoma was made. At the age of 29, the patient with primary amenorrhea had been evaluated clinically and cytogenetically. (1) The results of cytogenetic studies were X-chromatin positive and revealed a karyotype in peripheral blood leukocytes of 46,XX. (2) Laboratory studies indicated hypergonadotropic hypogonadism and no response of the gonads to the human menopausal gonadotropin stimulation test. (3) At laparotomy, the gonads were streak-like. Pathological examinations of biopsy specimens from both gonads revealed dense, fibrous connective tissue resembling ovarian stroma and no primary follicles. Eleven years after the laparotomy, the patient complained of lower abdominal distention and severe pain, and laparotomy then revealed a 15 X 17-cm right solid adnexal mass occupying the pelvic cavity. The histological diagnosis of tissues from the partially removed tumor was pure dysgerminoma. Second-look operation after Linac X-ray irradiation showed complete remission of the residual tumor. Insofar as we are aware, the present patient represents the first case of dysgerminoma which occurred in the dysgenetic gonads of a phenotypic female with normal 46,XX sex-chromosomal constitutions in peripheral blood leukocytes and the skin fibroblasts although a possibility exists that mosaicism was possibly present but undetected, particularly since the streak gonads were not analyzed chromosomally.

Effect of Increased Calcium Intake During the Third Trimester on the Vascular Sensitivity to Angiotensin II

Calcium supplementation during pregnancy reduces the vascular sensitivity to infused angiotensin II, but the dose of calcium required increases as pregnancy advances. In 24 patients given 600 mg/day of calcium L-aspartate from the 20th week of gestation, the effective pressor doses of angiotensin II at the 20th, 26th, 30th and 36th week of gestation were 18.4±1.1, 31.9±2.3, 39.0±3.0 and 25.7±2.4 ng/kg/min (mean±SEM), respectively. In this group, the decline in the effective pressor dose from the 30th to the 36th week of gestation was significant (p< 0.005). In 21 patients calcium L-aspartate was given at a dose of 600 mg/day from the 20th week and the dose was increased to 1200 mg/day after the 30th week, and the the effective pressor doses were 21.2±2.6, 31.8±3.2, 32.1±3.4 and 28.7±2.6 ng/kg/min at the 20th, 26th, 30th and 36th week of gestation, respectively. In this group, a significant decrease in the effective pressor dose between the 30th and the 36th week of gestation was not observed. In both grou...

Vasopressor activity in incubated plasma of normal and hypertensive pregnant women

The pressor activity generated in incubated plasma of nonpregnant, normal pregnant, and hypertensive pregnant women was measured by means of a sensitive bioassay technique. It was found that the plasma of normal pregnant women generated significantly higher amounts of active pressor principle than the plasma of nonpregnant women. The plasma of hypertensive pregnant women generated significantly lower amounts of active pressor principle than the plasma of normal pregnant women. Plasma obtained from the antecubital vein revealed no difference in pressor activity compared to plasma collected from the uterine vein at the time of cesarean section. These data suggest that active pressor principle is not involved in the pathogenesis of pregnancy-induced hypertension and that the pregnant uterus is not the source of active pressor principle.

Increased Pressor Response to Angiotensin II after Stricture of the Abdominal Aorta in Pregnant Rabbits

The abdominal aorta of 7 pregnant rabbits was treated below the renal arteries on the 21st day of pregnancy, producing a stricture which reduced the lumen to 2.0 mm in diameter. The pressor response to angiotensin II was assessed by measuring the systolic blood pressure of the ear using a Grant-Rothschild capsule. After stricture of the abdominal aorta, the systolic blood pressure in pregnant rabbits was not statistically different from that of sham operated rabbits. However, a significant increase in vascular reactivity to infused angiotensin II was demonstrated during the remaining gestational period.These findings suggest that interference with the blood supply of the pregnant uterus is an important factor in determining the vascular reactivity to angiotensin II in pregnant rabbits

Increase of plasma tissue-plasminogen activator antigen levels after induced abortion

SummaryWe previously reported that plasma thrombotic activity is transiently increased immediately after induced abortion. However, changes in the fibrinolytic system have not vet been studied. Plasma tissue-plasminogen activator (t-PA) antigen levels were studied before and after abortion induced during the first trimester of pregnancy. Compared with the preoperative level (1.68 ± 0.15 ng/ml), t-PA level was significantly increased (2.78 ± 0.55 ng/ml, p<0.01) 15 min after the induced abortion, while it almost returned to the preoperative values (2.09 ± 0.40 ng/ml) 2h later. This finding suggests that fibrinolytic activity is transiently increased immediately after the induced abortion, acting as a defense mechanism against thrombosis.We previously reported that plasma thrombotic activity is transiently increased immediately after induced abortion. However, changes in the fibrinolytic system have not yet been studied. Plasma tissue-plasminogen activator (t-PA) antigen levels were studied before and after abortion induced during the first trimester of pregnancy. Compared with the preoperative level (1.68 +/- 0.15 ng/ml), t-PA level was significantly increased (2.78 +/- 0.55 ng/ml, p less than 0.01) 15 min after the induced abortion, while it almost returned to the preoperative values (2.09 +/- 0.40 ng/ml) 2h later. This finding suggests that fibrinolytic activity is transiently increased immediately after the induced abortion, acting as a defense mechanism against thrombosis.