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Biomedical subjects

S B Amini

Publications and source records attributed to S B Amini.

51 records · Page 3Linked to original sources
PubMed1993

Weight gain in women with gestational diabetes.

OBJECTIVE: To evaluate weight gain during pregnancy in women with gestational diabetes, and to determine whether there was a stronger or weaker correlation of maternal weight gain with neonatal birth weight in women with gestational diabetes as compared with a control group. METHODS: At delivery, 78 women with gestational diabetes and 312 control subjects were evaluated and classified according to pregravid weight for height (underweight, average weight, and overweight). Weight gain during pregnancy and neonatal birth weight in the women with gestational diabetes and in the control group were compared using analysis of covariance, controlling for selected covariables. A weight gain curve for each patient was generated to assess the rate of weight gain during early, middle, and late gestation. Linear regression analysis was used to correlate maternal weight gain and birth weight. RESULTS: Weight gain was 2.5 kg less in the women with gestational diabetes as compared with the controls (P = .0006). When adjusted for pregravid weight, maternal age, and gestational age at delivery, only underweight women with gestational diabetes persisted in having significantly less weight gain as compared with the control subjects (P = .035). There were no significant differences in infant birth weight between any gestational diabetes and control weight categories. The rate of weight gain was decreased in over-weight women with gestational diabetes versus control subjects in late pregnancy (P = .05). There was a significant correlation between maternal weight gain and birth weight in underweight (r = 0.46, P = .0001) and average-weight (r = 0.17, P = .02) control women but not in overweight controls or in any patients with gestational diabetes. CONCLUSION: Weight gain in women with gestational diabetes is less than in control patients, primarily because of greater pregravid weight, and does not correlate with neonatal birth weight.

Adult↗
PubMed1992

Longitudinal changes in basal hepatic glucose production and suppression during insulin infusion in normal pregnant women.

OBJECTIVE: The purpose of this study was to evaluate basal endogenous glucose production and suppression during insulin infusion in normal pregnant women. STUDY DESIGN: This prospective, longitudinal study was conducted at the Medical Center Hospital of Vermont. Six healthy women were evaluated before conception and at 12 to 14 and 34 to 36 weeks' gestation. Body composition was estimated by hydrodensitometry. Basal endogenous glucose production was estimated with a primed constant infusion of 6-6 2H2 glucose, and suppression of endogenous glucose production was estimated with insulin infusion during a hyperinsulinemic-euglycemic clamp. RESULTS: There was a significant (p = 0.02) 65% increase in fasting insulin concentration by late gestation. Moreover, there was a significant 30% (p = 0.0005) increase in basal endogenous glucose production (mg/min) with advancing gestation, which remained significant (p = 0.05) when corrected for fat-free mass. During insulin infusion endogenous glucose production was almost completely suppressed (i.e., > 90%) throughout gestation. CONCLUSIONS: There is a significant increase in basal endogenous glucose production at 34 to 36 weeks' gestation in spite of a significant increase in fasting insulin concentration. However, endogenous glucose production remains sensitive to insulin infusion throughout gestation.

Adult↗
PubMed1992

Aberrant crypts correlate with tumor incidence in F344 rats treated with azoxymethane and phytate.

Aberrant crypts are putative preneoplastic lesions that have been proposed as intermediate biomarkers for colon cancer. The goals of these studies were to determine (i) if the colon cancer chemopreventive agent, sodium phytate, when started 1 week after a single dose of carcinogen, has any effect on the development of aberrant crypt foci (ACF) in treated rats; and (ii) if ACF at an early time period under these conditions correlate with the later formation of tumors in similarly treated animals. The number of ACF with four or more crypts was greater (P = 0.02, Mann-Whitney test) in rats with tumors compared with rats without tumors killed at 36 weeks after the injection of azoxymethane (AOM); the total number of ACF was not significantly different in these two groups. The incidence of tumors in F344 rats treated with AOM without phytate was 83% (10/12) compared to 25% (3/12) in rats treated with AOM plus phytate (P = 0.0045, two-tail Fisher's exact test). The finding of more (P = 0.005, Mann-Whitney test) ACF with four or more crypts in rats without phytate than in rats with phytate at 12 weeks after the injection of AOM is consistent with the hypothesis that the development of larger ACF (with four or more crypts) is predictive of the tumor incidence. These results validate the use of this parameter, i.e. ACF with four or more crypts, as an intermediate biomarker for tumor incidence in this system.

Animals↗
PubMed1991

Occurrence of respiratory syncytial virus subtypes in hospitalized children in Cleveland, Ohio from 1985 to 1988.

In order to determine the frequency of occurrence of the two respiratory syncytial virus (RSV) subtypes in hospitalized children in Cleveland, Ohio, we analyzed clinical isolates obtained during three consecutive winter epidemic seasons between 1985 and 1988. RSV was recovered from the frozen clinical specimens of 197 patients: 176 subtype A, and 21 subtype B. Subtype A predominated during all three epidemic seasons, ranging from 83 to 94% of isolates. We surveyed the clinical records of 16 children with subtype B, and 101 children with subtype A infections, hospitalized at the University Hospitals of Cleveland during these winter epidemics and found no differences in age, sex, race, or clinical spectrum of severity of disease caused by the two subtypes. In contrast to previously reported data, subtype A predominated in each of the winter seasons studied within this community. We conclude that both subtypes circulate concurrently within the community during the winter. In hospitalized children both subtypes appear to cause a similar spectrum of disease. Both the concurrent circulation of RSV subtypes and the similar spectrum of illness pose for important considerations in the development of effective vaccines against this common respiratory agent in children.

Antigens, Viral↗
PubMed1991

Longitudinal changes in insulin release and insulin resistance in nonobese pregnant women.

To assess the longitudinal changes in insulin release and insulin sensitivity in nonobese normal women during gestation, six women were evaluated with oral glucose tolerance testing, body composition analysis, intravenous glucose tolerance tests, and the hyperinsulinemic-euglycemic clamp before conception, at 12 to 14 weeks, and at 34 to 36 weeks' gestation. There was a significant increase in the insulin/glucose ratio (p = 0.028) during the oral glucose tolerance test during gestation. There was also a significant 3.0- to 3.5-fold increase throughout gestation in first-phase (p = 0.001) and second-phase (p = 0.0001) insulin release during the intravenous glucose tolerance test. Peripheral insulin sensitivity was estimated as the glucose infusion rate (in milligrams per kilogram fat-free mass per minute) during the hyperinsulinemic-euglycemic clamp. There was a significant (p = 0.0003) 56% decrease in insulin sensitivity through 36 weeks' gestation. These results are the first to prospectively evaluate the longitudinal changes in maternal carbohydrate metabolism from the time before conception through late gestation with newer methods such as the hyperinsulinemic-euglycemic clamp.

Administration, Oral↗
PubMed1991

Incidence and risk factors associated with abnormal postpartum glucose tolerance in women with gestational diabetes.

To determine the incidence and risk factors associated with an abnormal postpartum glucose tolerance in women with gestational diabetes, 103 patients with gestational diabetes had a 2-hour, 75 gm oral glucose tolerance test 6 +/- 2 weeks (mean +/- SD) after delivery. Twenty-two percent (23/103) of results were abnormal: Three showed frank diabetes, four showed impaired glucose tolerance, and 16 were, nondiagnostic. There was a significant difference in gravidity, pregravid weight and body mass index, delivery weight, gestational age at diagnosis, fasting and 2- and 3-hour glucose level at the time of the oral glucose tolerance test during pregnancy, need for insulin therapy during gestation, and neonatal weight greater than 4000 gm in the abnormal group as compared with the normal group. Elevated fasting glucose level (p = 0.0001) and earlier gestational age at time of diagnosis of gestational diabetes (p = 0.013) were found to be most predictive of an abnormal postpartum glucose tolerance test result. These results support the importance of postpartum oral glucose tolerance testing in women with gestational diabetes.

Adult↗
PubMed1990

Late events following repair of aortic coarctation with resection and end-to-end anastomosis: a twenty-five-year experience.

From November 24, 1964 through July 3, 1979, 81 patients underwent coarctation repair with resection and end-to-end anastomosis. Mean age at operation was 13.4 years, with a range of 4 months to 55 years. Thirty-two patients (39%) had associated cardiac defects. There were no hospital deaths. Eighty of the 81 hospital survivors were followed (99%) for a total of 10,780 months postoperatively, at a mean of 134.6 (+/- 7.1) months. There was one late death (1.3%) of a ruptured berry aneurysm at 120 months after repair. Actuarial survival was 100% at 10 years and 92.9 +/- 7% at 20 years. Five patients (6.3%) required late re-repair at a mean of 142.8 months postoperatively, range 85 months to 195 months. Actuarial freedom from reoperation was 97 +/- 2.0% at 5 years and 91.7 +/- 3.6% at 20 years. Earlier age at initial repair (P = 0.002), higher mean transrepair gradient (P = 0.005), and late hypertension (P = 0.08) were associated with re-coarctation. The hazard function for reoperation according to age at initial repair revealed a single early risk phase with a plateau starting at 7 years of age and zero hazard after 10 years of age. We conclude that correction of coarctation of the aorta using resection and end-to-end anastomosis permits a long history of event-free survival and continues to be an excellent method of repair.

Actuarial Analysis↗
PubMed1990

Pulmonary artery balloon counterpulsation for right ventricular failure after right ventriculotomy in the swine.

To assess the efficacy of intrapulmonary balloon counterpulsation in the management of right ventricular failure after right ventriculotomy, we undertook an experimental study in a swine model. To mimic the clinical settings more closely, (1) we left the automatic control of the heart intact (2) did not use cardiopulmonary bypass to support the left side of the heart, and (3) induced right ventricular failure by means of a generous surgical incision (50% to 70% of the anterior wall) of the right ventricle. The criteria set for right ventricular failure were (1) 50% increase in right ventricular end-diastolic pressure, (2) 30% decrease in mean arterial pressure, and (3) 30% decrease in cardiac output. Right ventricular failure was attained in all animals studied: A 230% increase in right ventricular end-diastolic pressure, a 43% decrease in cardiac output, and a 34% decrease in mean arterial pressure were evident after the right ventriculotomy. A specially designed intrapulmonary balloon catheter (Datascope Corp., Oakland, N.J.) was placed into the left pulmonary artery through the right ventricular outflow tract. A Datascope console was used for counterpulsation. Effects of counterpulsation for 40 minutes in a 1:1 mode were assessed after surgical induction of right ventricular failure in 14 swine. Each animal served as its own control. The mean hemodynamic changes are outlined: Right ventricular end-diastolic pressure decreased by 48.9% (p = 0.01). Mean arterial pressure increased by 68.8% (p = 0.01) and cardiac output by 44.2% (p = 0.01). Histologic studies disclosed no morphologic damage to the pulmonary artery or valve in the specimens analyzed. In addition, these results were compared with those in a second group of seven swine in which right ventricular failure was induced by right ventriculotomy and a balloon was placed into the left pulmonary artery but not activated. These results of short-term counterpulsation should be evaluated in a longer term model so as to mimic more closely the clinical setting. If the hemodynamic benefits are duplicated, intrapulmonary balloon counterpulsation should be considered as a simple, effective device when right ventricular failure develops after right ventriculotomy. It effectively improves right ventricular function without damaging the pulmonary artery or valve.

Animals↗
PubMed1989

Transient maternal hypotension following epidural anesthesia.

Transient maternal hypotension following regional anesthesia can lead to significantly lower umbilical cord pH values. Although this acidosis has not been found to be clinically significant, acidosis may increase the placental transfer of local anesthetic agents as a result of "ion trapping." The purpose of this study was to examine the pharmacologic and clinical consequences of transient maternal hypotension following epidural anesthesia with 0.5% bupivacaine before cesarean section. Patients were divided into two groups based on the development of maternal hypotension, defined as a systolic blood pressure less than 100 torr or a decrease of 30% or more from the preanesthetic level. Thirteen patients (33%) developed hypotension that was corrected within 2.1 +/- 1.8 min. The pH of umbilical cord venous and arterial blood and the concentration of bupivacaine were significantly lower (P less than 0.05) in neonates of mothers in the hypotensive group than in neonates of mothers that did not develop hypotension. The results show, however, that transient maternal hypotension following epidural anesthesia does not lead to a greater placental transfer of bupivacaine due to "ion trapping" even though neonatal cord blood pH decreases.

Adult↗
PubMed1985

Consideration of covariates and stratification in sample size determination for survival time studies.

Sample size determination for survival time studies is discussed, taking into account stratification. We present formulas and tables which also apply in the case of multicenter clinical trials. In addition, the same method is used to estimate the sample size requirement when a covariate is grouped into strata. Simulation studies compare the results to covariate adjustment by the Cox proportional hazards model.

Follow-Up Studies↗
PubMedDate not supplied

Effect of prenatal care on obstetrical outcome.

The purpose of this study was to examine the demographic and obstetrical outcomes of women with poor prenatal care. A 7-year (1987-1993) computerized perinatal database with 29,225 consecutive deliveries was collected prospectively from a single inner city tertiary medical center. Data from 23,181 women who had documented prenatal visits during their pregnancies were used in the analysis. Overall, 21,004 (90.6%) of the mothers had at least 3 prenatal visits (C), while 2,177 (9.4%) had 2 or fewer visits (NC). The proportion of NC did not change significantly over the years (P = 0.47, by trend test). The NC group was 2.3 times more likely to be unmarried (79.8% vs. 59.4%; P < 0.001), have greater parity (mean +/- SD 2.1 +/- 1.9 vs. 1.2 +/- 1.2; P < 0.001), 6.3 times more likely to be staff patients (have no private insurance), and 1.5 times more likely to be black. The average maternal age was 24 years for both groups (P = 0.65). NC mothers delivered at an earlier gestational age (37.3 +/- 3.3 vs. 39.0 +/- 2.6 weeks; P < 0.001), had lower birth weights (BW) (2,810 +/- 743 vs. 3,203 +/- 607 g for singleton births; P < 0.001), and their infants had longer neonatal hospital stays (8.4 +/- 17.3 vs. 4.8 +/- 10.4 days; P < 0.001) compared with C mothers. Moreover, after adjusting for various confounding factors known to effect BW, C mothers delivered infants which were on the average 550 g heavier than the NC mothers. The neonates of NC had consistently lower Apgar scores and were more likely be delivered in breech presentation (5.7% vs. 3.1%) and to be transferred to the neonatal intensive care unit (11.6% vs. 5.2%; P < 0.001). However, the NC group had fewer cesarean deliveries (9.4% vs. 14.2%; P < 0.001) but more thick meconium fluid (12.4% vs. 8.9%; P < 0.001). In conclusion, the women not seeking adequate prenatal care are more likely to be unmarried, black, and staff patients having several children at home. NC mothers tend to have poor obstetrical outcomes and on the average their neonatal stay in the hospital is twice as long as women obtaining adequate prenatal care.

Adolescent↗
PubMedDate not supplied

Effects of maternal exercise on fetal activity in late gestation.

In order to test the effects of maternal exercise in late gestation on fetal biophysical activities as measured by fetal breathing, shoulder movement, and kick response, these parameters were monitored by ultrasound in ten healthy pregnant women at 35 weeks of gestation before and after 20 minutes of aerobic dance and before and after 20 minutes of rest. A randomized crossover design between exercise (sequence A) and rest (sequence B) that used each pregnant woman as her own control was used in this study. Cumulative means for each fetal activity were compared. Results indicated a significant decrease in fetal breathing after maternal exercise and no significant change in shoulder movements or kick response.

Adult↗
PubMedDate not supplied

Magnitude and likelihood of loss resulting from non-stratified randomization.

We investigate the power of detecting treatment differences by the stratified logrank test for balanced samples as compared to samples with unequal allocation to treatments within strata. Given non-stratified randomization to treatments, we relate power losses to their probability of occurrence. In addition, we evaluate the likelihood of zero cells. For power calculations, we employ an asymptotic formula and complement by Monte Carlo simulations to verify results in small samples. In the cases investigated, our results show that large power losses due to imbalance are relatively unlikely with 2 strata. Small strata, however, involve a non-negligible probability of wasting all observations because of zero cells or censoring.

Clinical Trials as Topic↗