Digitalis-like factor response to hyperinsulinemia in human pregnancy, a model of insulin resistance

Insulin resistance is strongly associated with hypertension and is postulated to participate in the elevation of blood pressure, although the mechanisms involved are not understood. Recently, we reported that acute increases in plasma insulin levels in normal subjects resulted in increased serum levels of a sodium pump inhibitor, termed the digitalis-like factor (DLF), which has been implicated in both experimental and essential human hypertension. This study looked at the DLF response to hyperinsulinemia, achieved by an oral glucose tolerance test (OGTT), in the setting of a naturally occurring and self-resolving state of human insulin resistance, during third-trimester pregnancy. This model allowed us the further opportunity to compare the DLF response to insulin in the same subjects postpartum, after resolution of their insulin resistance. Administration of an OGTT during pregnancy and postpartum in the same subjects elicited a comparable serum glucose response but a significantly greater insulin response during third-trimester pregnancy, consistent with diminished insulin sensitivity (integrated insulin response during pregnancy: 1611+/-236 vs postpartum: 685+/-101 pmol/l, P=0.004). The time courses of the glucose and insulin responses were identical whether women were pregnant or not. Plasma free fatty acids fell significantly and to a comparable degree during pregnancy and postpartum, but the response was slower during pregnancy. DLF levels increased in response to oral glucose in both pregnant and nonpregnant states. The response was more rapid during pregnancy than after. These findings showed that the increment of insulin induced by oral glucose during pregnancy caused a more rapid rise in circulating DLF levels than it did during the nonpregnant state. At the same time, the response of circulating fatty acids to glucose is retarded during pregnancy. This suggests that the insulin resistance of pregnancy impairs insulin's influence on intermediary metabolism but not its influence on DLF. As a vasoactive substance, DLF might contribute to the hypertension characteristic of insulin-resistant states.

Characterization of a high-gain harmonic-generation free-electron laser at saturation

We report on an experimental investigation characterizing the output of a high-gain harmonic-generation (HGHG) free-electron laser (FEL) at saturation. A seed CO2 laser at a wavelength of 10.6 microm was used to generate amplified FEL output at 5.3 microm. Measurement of the frequency spectrum, pulse duration, and correlation length of the 5.3 microm output verified that the light is longitudinally coherent. Investigation of the electron energy distribution and output harmonic energies provides evidence for saturated HGHG FEL operation.

Cigarette smoking and pre-eclampsia: their association and effects on clinical outcomes

OBJECTIVE

To determine the effects of smoking on pre-eclampsia in an inner-city, predominantly African-American prenatal population.

METHODS

We performed a retrospective cohort study of all primigravidas who delivered singletons in our institution between 1980 and 1989. The study population consisted of 1862 smokers and 16,508 non-smokers. Univariate analysis and multiple logistic regression were used to identify relationships between smoking and adverse outcomes.

RESULTS

The pre-eclampsia rate was significantly lower among smokers (11.3% vs. 13.0%, OR 0.85, 95% CI 0.73-0.99). Smokers with pre-eclampsia had higher rates of infants with low birth weight (OR 1.44, 95% CI 1.26-1.65) and very low birth weight (OR 1.85, 95% Cl 1.55-2.20) and higher rates of placental abruption (OR 3.49, 95% CI 1.65-7.28) compared to non-smoking pre-eclamptics. This relationship persisted after correction for age, race, chronic hypertension and pre-eclampsia as confounding variables.

CONCLUSIONS

Cigarette smoking was associated with a lower rate of pre-eclampsia among primigravidas independently of other maternal factors. Perinatal outcomes were significantly worsened among pre-eclamptics who smoked.

Vaginal birth after cesarean among women with gestational diabetes

OBJECTIVE

We sought to determine the pregnancy and infant outcomes of women with gestational diabetes who attempted vaginal birth after previous cesarean delivery.

STUDY DESIGN

We conducted a retrospective cohort study to compare women with gestational diabetes with matched control subjects without diabetes who attempted vaginal birth after cesarean at Grady Memorial Hospital, Atlanta, from January 1, 1989, through December 31, 1999. One hundred fifty-six women with gestational diabetes were matched with 272 control subjects. Data were analyzed with the Student t test, chi2 analysis, and the Fisher exact test.

RESULTS

The parities of the women with gestational diabetes and the control subjects were similar, with most having had only one previous pregnancy. Women with gestational diabetes were significantly older than control subjects and more likely to be white or Hispanic. Women with gestational diabetes who attempted a trial of labor were significantly more likely than control subjects to be delivered abdominally. Women with gestational diabetes who had a successful vaginal birth after cesarean were significantly more likely than control subjects to have an operative delivery with forceps or vacuum.

CONCLUSION

Women with gestational diabetes are less likely than those without diabetes to have a successful trial of labor. Women with gestational diabetes considering vaginal birth after cesarean should be appropriately counseled about the risk of attempting a trial of labor after previous cesarean delivery.

Trends in operative vaginal delivery rates and associated maternal complication rates in an inner-city hospital

OBJECTIVE

The aims of this study were to determine trends in operative vaginal delivery rates in a large inner-city hospital and to assess associated risks.

STUDY DESIGN

We performed a retrospective cohort study (1980-1996) of women with singleton term pregnancies who underwent operative vaginal delivery at Grady Memorial Hospital, Atlanta. Maternal complication rates were compared between forceps-assisted and vacuum-assisted methods.

RESULTS

There was a decline in forceps-assisted deliveries during the 1980s and an increase during the 1990s. The vacuum-assisted delivery rate was exceedingly low during the 1980s and increased during the 1990s. Women who underwent forceps-assisted delivery were more likely to be <24 years old, to be nulliparous, and to have had regional anesthesia, midline episiotomies, and infant presentations other than occipitoanterior (P <.001). Women who underwent forceps-assisted deliveries had increased risks of postpartum infection, cervical laceration, prolonged hospital stay, perineal laceration, and postpartum complications.

CONCLUSION

There were upward trends in the rates of operative vaginal delivery at this inner-city hospital. Women who underwent forceps-assisted delivery had greater rates of maternal complications than did those who underwent vacuum-assisted delivery.

The effect of epidural analgesia on rates of episiotomy use and episiotomy extension in an inner-city hospital

OBJECTIVE

To determine the relationship between epidural analgesia and episiotomy usage and episiotomy extension in parturients delivering vaginally.

METHODS

A database of 20 888 women experiencing spontaneous vaginal delivery at Grady Memorial Hospital from 1990 to 1995 was examined to identify those receiving epidural analgesia. Patients who underwent epidural catheter placement and had adequate perineal anesthesia at delivery comprised the epidural group, and all others comprised the control group. Demographic characteristics and obstetric outcomes were compared. Univariate and multivariate analyses were used to test the association between epidural analgesia, rates of episiotomy and episiotomy extension.

RESULTS

Of the 20888 women experiencing spontaneous vaginal deliveries 6785 (32.5%) received epidural analgesia. Women receiving epidural analgesia were more likely than those not receiving epidural analgesia to be African-American and nulliparous, and to have an occiput posterior presentation. Women receiving epidural analgesia were also more likely to receive an episiotomy (27.8% vs. 13.1%, odds ratio (OR) 2.56, 95% confidence interval (CI) 2.38-2.75) and were less likely to experience a second-degree perineal laceration (11.6% vs. 14.4%, OR 0.75, 95% CI 0.69-0.82) or a third- or fourth-degree extension (8.9% vs. 12.4%, OR 0.81, 95% CI 0.68-0.97). When the results were adjusted for nulliparity, posterior presentation, macrosomia, shoulder dystocia and prolonged second stage, epidural analgesia remained independently associated with receipt of episiotomy (OR 1.97, 95% CI 1.88-2.06) and reduced episiotomy extension (OR 0.74, 95% CI 0.54-0.94).

CONCLUSION

Epidural analgesia increases the rates of episiotomy use, and decreases the rate of episiotomy extension, independently of clinical factors associated with episiotomy.

High-gain harmonic-generation free-electron laser

A high-gain harmonic-generation free-electron laser is demonstrated. Our approach uses a laser-seeded free-electron laser to produce amplified, longitudinally coherent, Fourier transform-limited output at a harmonic of the seed laser. A seed carbon dioxide laser at a wavelength of 10.6 micrometers produced saturated, amplified free-electron laser output at the second-harmonic wavelength, 5.3 micrometers. The experiment verifies the theoretical foundation for the technique and prepares the way for the application of this technique in the vacuum ultraviolet region of the spectrum, with the ultimate goal of extending the approach to provide an intense, highly coherent source of hard x-rays.

Alzheimer's disease comorbidity in normal pressure hydrocephalus: prevalence and shunt response

The clinical impact of Alzheimer's disease pathology at biopsy was investigated in 56 cognitively impaired patients undergoing shunt surgery for idiopathic normal pressure hydrocephalus (NPH). Cognition was measured by means of the global deterioration scale (GDS), the mini mental status examination (MMSE) and a battery of six psychometric tests. Gait was assessed using objective measurements of velocity and the ambulatory index (AI). The prevalence of cases exhibiting neuritic plaques (positive biopsies) increased in parallel with dementia severity from 18% for patients with GDS 3 to 75% for patients with GDS scores > or =6. Patients with positive biopsies were more cognitively impaired (higher GDS and lower MMSE scores) as well as more gait impaired (higher AI scores and slower velocities) than patients with negative biopsies. After surgery, gait velocity and AI scores improved significantly and to a comparable degree for patients with and without positive biopsies. Similar proportions of positive and negative biopsy patients also had improved gait as assessed by means of subjective video tape comparisons. There were no significant differences between the biopsy groups in the magnitude of postoperative psychometric change or in the proportion of cases exhibiting improved urinary control. Alzheimer's disease pathology is a common source of comorbidity in older patients with idiopathic NPH where it contributes to the clinical impairment associated with this disorder. For patients accurately diagnosed with NPH, concomitant Alzheimer's disease pathology does not strongly influence the clinical response to shunt surgery.

Racial patterns in the effects of tobacco use on fetal growth

OBJECTIVE

The aim of this study was to characterize the interaction between the effects on fetal growth of maternal smoking and race by means of race-specific growth normograms.

STUDY DESIGN

A case-control study was performed on white and African American mothers who were delivered at 2 hospitals in metropolitan Atlanta between February 1993 and December 1994. The study population consisted of 621 small for gestational age infants and their mothers and 324 appropriate for gestational age infants and their mothers. Face-to-face interviews with mothers and detailed anthropometric measurements of neonates were performed. Relationships among tobacco use, race, and fetal growth were evaluated by means of multiple logistic regression. The chi(2) test of trend was performed to assess a dose-response relationship between smoking and fetal growth.

RESULTS

Mothers of small for gestational age neonates were significantly more likely than control mothers to be single (52% versus 40%), to be primiparous (47% versus 37%), to have a low body mass index (26% versus 17%), to have hypertension (22% versus 15%), and to use alcohol (15% versus 9%). Mothers of small for gestational age infants were significantly more likely than control mothers to smoke (26% versus 12%) and to smoke more cigarettes (P <.05). After controlling for potential confounders cigarette smoking in the second trimester was significantly associated with small for gestational age infants in both races (whites <1 pack/d adjusted odds ratio 3.82, 1-2 packs/d adjusted odds ratio 4.86, >2 packs/d crude odds ratio; African Americans <1 pack/d adjusted odds ratio 2. 35, 1-2 packs/d adjusted odds ratio 2.52). The chi(2) test of trend results were consistent with a dose-response relationship between smoking and small for gestational age infants (whites chi(2) = 14.06, P <.0001, African Americans chi(2) = 7.99). Comparison between the 2 races of the adverse effects of smoking on fetal growth showed no significant difference.

CONCLUSION

Self-reported maternal smoking during the second trimester is associated with fetal growth restriction in a dose-response manner. According to race-specific growth normograms no significant difference in the effects of tobacco use on fetal growth was found between white and African American women.

Adverse perinatal outcome in parturients who use crack cocaine

OBJECTIVE

To determine the risk of adverse pregnancy outcome among crack cocaine users in a large homogeneous prenatal population with objective documentation of drug use.

METHODS

A retrospective cohort study was performed on a population of inner-city women who were offered routine voluntary urine drug screening and who delivered between January and December 1992 at a large county hospital. The study population consisted of 483 users (positive drug screens) and 3158 non-users (negative drug screens). Univariate analysis and multiple logistic regression were used to identify the relation between crack cocaine use and adverse perinatal outcome.

RESULTS

Users were significantly more likely than nonusers to deliver low birth weight (LBW) infants (31.3% versus 14.9%; crude odds ratio [OR] 2.6; 95% confidence interval [CI] 2.1, 3.2), growth-restricted infants (29.0% versus 13.0%; crude OR 2.7; 95% CI 2.2, 3.4), and preterm infants (28.2% versus 17.1%; crude OR 1.9; 95% CI 1.5, 2.4). In addition, users were more likely to have abruptions (3.3% versus 1.1%; crude OR 3.0; 95% CI 1.6, 5.6) and infants with low 5-minute Apgar scores (7.9% versus 4.5%; crude OR 1.8; 95% CI 1.2, 2.7). After adjusting for confounders (including alcohol use and smoking), only the risks of LBW and fetal growth restriction (FGR) remained significant, with adjusted OR 1.6 (95% CI 1.03, 2.4) and adjusted OR 1.7 (95% CI 1.2, 2.3), respectively. Although there was no significant difference in the rate of low 5-minute Apgar scores between users and non-users after controlling for confounders, users with a positive urine drug screen within 1 week of delivery were significantly more likely than non-users to deliver infants with low 5-minute Apgar scores: crude OR 2.4; adjusted OR 2.0 (95% CI 1.1, 3.7).

CONCLUSION

In this inner-city population, crack cocaine use is associated with adverse pregnancy outcomes, as noted by increased risks of LBW and FGR.

Bartter's syndrome in pregnancy: a case report and review

Bartter's syndrome is a rare autosomal recessive disorder characterized by hypokalemia, hyperaldosteronism, sodium wasting, normal blood pressure, hypochloremic alkalosis, and hyperplasia of the juxtaglomerular apparatus. We present a 21-year-old African-American nulliparous patient who was referred to our clinic at 9 weeks' gestation with a history of Bartter's syndrome. Her antenatal course was complicated by muscle cramps, which required increasing potassium supplementation. She developed hypomagnesemia in the third trimester of pregnancy, which necessitated magnesium therapy. She delivered an unaffected infant at term. Bartter's syndrome, although extremely rare in pregnancy, requires prompt recognition and careful management, as it may have significant maternal and neonatal implications.

Condom use and breakage among women in a municipal hospital family planning clinic

For those who choose to be sexually active, condoms are the best available means of protection against sexually transmitted diseases including the human immunodeficiency virus (HIV), which causes acquired immunodeficiency syndrome (AIDS). Condoms are also an effective method for preventing pregnancy. Unfortunately, condoms are not 100% effective at preventing pregnancy or the spread of infection, in part because condoms do break. In order to gain insight into condom breakage, a questionnaire was administered to women attending a municipal hospital family planning clinic. Thirty-six percent of the 106 subjects had experienced at least one condom breakage. Condom breakage occurred in approximately 1 out of 100 acts of intercourse using condoms, with a lifetime breakage rate of 10 per 1000 condom uses and a past year breakage rate of 8 per 1000 condom uses. Breakage rates did not differ substantially by age. Five percent of the women's unplanned pregnancies were attributed to broken condoms. The results of this study corroborate previously reported rates. Factors associated with these women's most recent breakage experiences included: vaginal intercourse, minimal foreplay, and breakage prior to ejaculation. Controlled studies will be needed to determine how the condom can be used to reduce the likelihood of breakage.

High flow carotid cavernous fistula on magnetic resonance imaging with excellent angiographic correlation

Magnetic resonance imaging and angiographic findings of a carotid cavernous fistula are presented in a 22- year-old male who sustained a severe head injury.

Ectopic pregnancy. What to do during the 20-day window

An analysis of serial serum human chorionic gonadotropin (hCG) levels in 357 pregnant women revealed that the rise in hCG in normal intrauterine pregnancies differed from that in both ectopic gestations and abnormal intrauterine pregnancies. However, measurement of serial hCG levels cannot differentiate an ectopic from an abnormal intrauterine pregnancy. A protocol was developed for the management of patients with suspected ectopic pregnancy before ultrasound can reliably confirm an intrauterine gestation.

The relationship of one abnormal glucose tolerance test value and pregnancy complications

While an abnormal oral glucose tolerance test (GTT) is known to be associated with an increased risk of pregnancy complications, the impact of one abnormal value is not clear. In 1986 we screened 4618 pregnant women for gestational diabetes at 24-28 weeks' gestation. Eighty-seven percent had normal results; of the 13% with abnormal screening tests, 139 had one abnormal value on the subsequent 3-hour oral GTT. These women were then compared with 725 randomly selected patients with a normal screening test. The frequency of chronic hypertension, cesarean section, 5-minute Apgar score below 7, preterm delivery, shoulder dystocia, congenital malformations, and perinatal mortality did not differ significantly between the groups. The incidence of macrosomia (birth weight above 4000 g) was significantly greater in the study group (18.0%) than in the control group (6.6%) (odds ratio 2.18; 95% confidence interval 1.77-5.37), a relationship that persisted after controlling for confounding risk factors by logistic regression modeling (odds ratio 2.55; 95% confidence interval 1.44-4.52). The incidence of preeclampsia/eclampsia was significantly greater in the study group (7.9%) than in the control group (3.3%) (odds ratio 2.51; 95% confidence interval 1.14-5.52), which also persisted after controlling for confounding risk factors using logistic regression modeling (odds ratio 2.81; 95% confidence interval 1.26-6.28). Our results suggest that patients with one abnormal value on an oral GTT during pregnancy are at risk for delivering macrosomic infants and developing preeclampsia/eclampsia.

Influence of site of regional ischemia on LV cavity shape change in dogs

We assessed whether altering the location of acute ischemia produced differing and consistent changes in cavity shape in the canine left ventricle. Twenty anesthetized open-chest dogs underwent transient occlusion of the left anterior descending (LAD) or circumflex (Circ) artery, and cavity shape change was recorded in two-dimensional short-axis echocardiograms. The extent of injury was assessed by radiolabeled microspheres. Shape was analyzed by converting digitized endocardial contours into polar form and expressing the result as a Fourier series. Series terms reflected specific shape deformations, i.e., 2nd term would equal "elongation," 3rd term would equal "triangular." During LAD occlusions, 32.5 +/- 3.0% of the ventricle was hypoperfused compared with 29.8 +/- 2.9% during Circ occlusions (NS). Normal ventricular shape became more circular during ejection indicated by a reduction in the power in nearly all of the Fourier spectra components. During Circ occlusion, the chamber became more elongated, seen in a 63 +/- 16% rise in the 2nd component, and overall shape significantly less circular at end systole than at end diastole. LAD occlusion produced an entirely different pattern, one with no significant elongation but the development of a more triangular shape (86 +/- 27% rise in the 3rd term) by end systole. We conclude that there are characteristic and contrasting shape deformations in LV short-axis contours that depend on the site of ischemic injury. These changes may relate to site-specific geometry and loading, and they point to potential limitations of left ventricular models that do not account for regional inhomogeneity.

Disproportionate epicardial dilation after transmural infarction of the canine left ventricle: acute and chronic differences

The relation between acute disproportionate infarct dilation and late postinfarct left ventricular remodeling was examined by implanting multiple radiopaque epicardial markers in the left ventricle of eight dogs and determining regional surface deformation after acute and chronic transmural infarction. Transmural injury was produced by combining coronary ligation with distal embolization of a rubber polymer. Dogs were anesthetized and studied before and 1 h, 24 h and 1 week after infarction. Marker positions were recorded by rapid biplane cineradiography, and three-dimensional coordinates were reconstructed by a computer-assisted tracking system. Regional deformation was expressed by a local surface area equal to the sum of multiple (three to four) triangles generated by marker triplets. As early as 1 h after infarction, end-diastolic area in the infarct region increased by 20.3 +/- 3.1%, while that in the remote region increased by only 7.9 +/- 3.5%. Both changes and the difference between them were significant. At 24 h after infarction, both territories continued to undergo dilation, this time to a similar extent (additional +10.3% in the remote region and +10.1% in the infarct region), thus maintaining the significant disproportionate infarct dilation. At 1 week, however, the infarct territory remained dilated with a mean end-diastolic area 31.4 +/- 3.1% above control, while that in the remote region returned to a net mean 8.5 +/- 4.7% increase. Thus, the major extent of disproportionate infarct dilation occurs within 1 h after transmural injury and is accompanied by remote dilation as a compensatory response. The extent of further infarct dilation achieved by 24 h is maintained in the chronic infarct, and compensatory mechanisms enable noninjured myocardium to become less dilated.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of a conductance (volume) catheter and transient inferior vena caval occlusion for rapid determination of pressure-volume relationships in man

Determination of left ventricular pressure-volume relationships in situ ideally requires both a method for easy measurement of multiple pressure-volume loops and a rapid and reversible means of altering load. We report a technique, previously used in animals, that combines conductance catheter volumes and rapid inferior vena caval occlusion to permit routine measurement of calibrated P-V relationships in man for the first time. An 8F volume catheter with a 3F micromanometer tipped pressure catheter placed through its lumen was advanced to the left ventricular apex through a femoral artery. A thermodilution output catheter was placed through a 9F femoral venous sheath and later replaced with an IVC balloon occlusion catheter, through which a 2.5F bipolar wire was advanced for atrial pacing. A specialized data system facilitated collection, editing, and data analysis at the time of cardiac catheterization. Absolute volume calibration required cardiac output measurement and injection of hypertonic saline. IVC occlusion decreased peak left ventricular pressure by 42 +/- 17 (SD) (P less than .001) mm Hg in 15 patients. Endsystolic pressure-volume relationships (ESPVR) were determined with 5-8 cardiac cycles with an average of r2 of 0.94 +/- 0.05 and were generally reproducible. The slope of the ESPVR demonstrated consistency among a group of normal patients (n = 6), and was significantly lower than the slope derived from a group of patients with ventricular hypertrophy (n = 9). We conclude that left ventricular pressure-volume relationships can be easily and repeatedly determined as part of a routine cardiac catheterization in man.

Sexual arousal and aggression in a free-choice situation

The effect of sexual arousal on the administration of pleasure or pain to a rat was studied. The subjects were 40 male college students, half were induced to sexual arousal through reading erotic passages while the rest read neutral passages. Subjects were placed in a simulated teaching situation, with a laboratory rat being the apparent learner. Pleasurable and painful stimulation were available as teaching aids. No differences between the aroused and nonaroused groups were noted in intensity of stimulation applied; however, aroused subjects administered pain of greater duration than nonaroused subjects. This finding was attributed to a disinhibition effect operating in the aroused group. Such a difference might lead the aroused subjects to be labelled as more aggressive.

Participants' perceptions of ethical issues in research with humans

The recent concern about ethical issues in research with human subjects has fostered an interest in learning more through empirical methods. The present study provides information from potential participants regarding (1) their perception of the likelihood of physical or emotional harm from various experimental procedures and (2) their willingness to participate in experiments using such procedures. Responses were obtained from 1,586 students in introductory psychology classes and were analyzed on the basis of the respondents' age, sex, class standing, and academic major. Besides providing normative data from a typical subject pool, the present study suggests a method of using a research questionnaire as a way of minimizing the chances of offending individual subjects.