Three-dimensional echocardiography and strain cardiac imaging in women with pre-eclampsia with follow-up to 6 months postpartum

OBJECTIVE

Epidemiological studies have established that women with pre-eclampsia (PE) are at increased long-term cardiovascular risk. Mild cardiac functional changes have been documented during pregnancy in women with PE, but their evolution from presentation to the postpartum period remains poorly defined. The aim of this study was to assess biventricular cardiovascular indices using novel and sensitive two-dimensional and three-dimensional (3D) echocardiographic modalities in pregnancy and to track alterations in both risk factors and cardiovascular indices in the postpartum period.

METHODS

A total of 59 women with PE were examined at 34 (interquartile range, 31-37) weeks' gestation and at 2-3 days, 3 months and 6 months postpartum. During pregnancy, 118 women with a normotensive pregnancy were also recruited as controls. Biventricular ejection fraction and left ventricular mass were measured by 3D echocardiography. Biventricular global longitudinal strain and strain of the left atrium were assessed using speckle-tracking imaging.

RESULTS

In women with PE, compared with controls, there was lower left ventricular diastolic function (left atrial reservoir strain, 44.1% vs 49.2%) and increased left ventricular mass index (148 vs 128 g/m2 ), but there was no significant difference in right ventricular functional indices. These alterations in cardiac indices were mostly explained by differences in maternal risk factors. In the postpartum period, most cardiac indices improved by 3 months. Multivariable linear mixed-model analysis demonstrated that this improvement was mostly attributed to reduction in weight and blood pressure.

CONCLUSION

In women with PE, there is postpartum improvement in cardiac functional and structural indices in parallel with improvement in their risk factor profile. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Maternal cardiac function in twin pregnancy at 19-23 weeks' gestation

OBJECTIVES

To compare maternal cardiovascular indices at 19-23 weeks' gestation between twin and singleton pregnancies and assess the impact of chorionicity on these parameters.

METHODS

This was a prospective observational study in women with twin pregnancy attending for a hospital visit at 19 + 1 to 24 + 3 weeks' gestation. This visit included recording of maternal demographic characteristics and medical history and maternal cardiovascular assessment. In a previous study of 4795 women with singleton pregnancies at 19-23 weeks' gestation, multivariable linear regression models were fitted between the various cardiovascular indices and elements of maternal characteristics and medical history. In this study, we calculated multiples of the median (MoM) and delta values according to the singleton models and assessed the distributional properties of these MoM and delta values in twin as compared with singleton pregnancies.

RESULTS

The study population of 155 women with twin pregnancy included 86 dichorionic and 69 monochorionic cases. In general, there was a similar distribution of maternal cardiovascular indices in monochorionic and dichorionic twin pregnancies. In both types of twin pregnancy, compared with singleton pregnancy, there was an increase in isovolumetric relaxation time, left atrial area and myocardial performance index, and a decrease in mitral valve E/A. Left ventricular mass indexed for body surface area and relative wall thickness were also increased in twin compared with singleton pregnancy. The magnitude of the increase in left atrial area was greater in dichorionic compared with monochorionic pregnancies. Additionally, mitral valve E was decreased and left atrial volume was increased in dichorionic but not in monochorionic pregnancies, while isovolumetric contraction time was increased in monochorionic but not in dichorionic pregnancies. Left ventricular myocardial deformation was similar between twin and singleton pregnancies.

CONCLUSIONS

In twin pregnancies at mid-gestation, maternal systolic and diastolic function is reduced when compared with singletons. The patterns of cardiovascular adaptation are similar between monochorionic and dichorionic pregnancies and resemble those reported in uncomplicated singleton pregnancy later in gestation. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Sex differences in mortality in stable patients undergoing vasodilator stress cardiovascular magnetic resonance

Introduction

The prognostic value and therapeutic implications of ischemia as derived from vasodilator stress cardiovascular magnetic resonance (CMR) could differ in men and women, but it has not been stablished.

Purpose

We assessed the influence of the ischemic burden as derived from CMR on the risk of death and the effect of revascularization across sex.

Methods

We evaluated 6,237 consecutive patients with known or suspected chronic coronary syndrome (CCS). Extensive ischemia was defined as >5 segments with perfusion deficit. Multivariate Cox proportional hazard regression models were used.

Results

A total of 2,371 (38.0%) patients were women and 583 (9.3%) underwent CMR-related revascularization. During a median follow-up of 5.13 years, 687 (11.0%) deaths were reported. We found an adjusted differential effect of CMR-derived ischemic burden across sex (p-value for interaction=0.039). Women exhibited an adjusted lower risk of death along most of the continuous ischemic burden but equalled men's risk when extensive ischemia was present. Likewise, CMR-related revascularization was shown to be differentially associated with the risk of mortality across sex (p-value for interaction=0.025). In patients with non-extensive ischemia, revascularization was related to a higher risk of death, with a greater extent in women. At higher ischemic burden, revascularization was associated with a lower risk in men, with more uncertain results in women.

Conclusions

CMR-derived ischemic burden allows predicting the risk of death and gives insight into the potential effect of revascularization in men and women with CCS. Compared to men, women with nonextensive ischemia displayed a lower risk and a similar risk with a higher ischemic burden. The impact of CMR-related revascularization on mortality risk was also significantly different according to ischemic burden and sex.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): This study was supported by the Instituto de Salud Carlos III and cofunded by the European Regional Development Fund (ERDF).

Sex differences on new-onset heart failure in patients with known or suspected chronic coronary syndrome

Background

The impact of sex in patients with chronic coronary syndrome (CCS) has been widely reported, but little is known about the influence of sex on the risk of new-onset HF in patients with CCS.

Objectives

We aimed to examine sex-related differences and new-onset heart failure (HF) risk in patients with known or suspected CCS undergoing vasodilator stress cardiac magnetic resonance (CMR).

Methods

We prospectively evaluated 5,899 consecutive HF-free patients submitted to stress CMR for known or suspected CCS. Ischemic burden (number of segments with stress-induced perfusion deficit) and left ventricular ejection fraction (LVEF) were assessed by CMR. The association between sex and new-onset HF (including outpatient diagnosis or acute HF hospitalization) was evaluated using a Cox proportional-hazards regression model adjusted for competing events (death, myocardial infarction, and non-CMR-related revascularization).

Results

A total of 2,289 (38.8%) patients were women, and 539 (9.1%) underwent CMR-related revascularization. During a median follow-up of 4.5 years, 610 (10.3%) patients died, 191 (3.2%) suffered a myocardial infarction, 420 (7.1%) underwent CMR-non-related revascularization, and 314 (5.3%) developed new-onset HF. Unadjusted new-onset HF rates were higher in women than in men (1.25 vs 0.83 per 100 person/years, p=0.002) (Figure 1). After comprehensive multivariate adjustment, women showed an increased risk of new-onset HF (HR=1.61, 95% CI: 1.21–2.13, p=0.001). Compared with men, the risk of new-onset HF was higher in women with LVEF >53%.

Conclusions

Compared with men, women with CCS are at a higher risk of new-onset HF. Further studies are needed to unravel the mechanisms behind these sex-related differences.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Instituto de Salud Carlos III and Fondo Europeo de Desarrollo Regional (FEDER) Figure 1

Three-dimensional echocardiography and cardiac strain imaging in women with gestational diabetes mellitus

OBJECTIVES

Gestational diabetes mellitus (GDM) is associated with premature cardiovascular disease and adverse cardiovascular outcome in the mother. Subclinical cardiac functional changes in the left ventricle have been reported during pregnancy in women with GDM using conventional echocardiography, but results are inconsistent. The aims of the current study were to assess whether GDM is associated with biventricular systolic dysfunction in the mother and whether these cardiac changes can be detected using the novel echocardiographic modalities of strain imaging and three-dimensional (3D) echocardiography.

METHODS

This was a cross-sectional study in women with GDM and controls examined at 26-40 weeks of gestation. All women underwent echocardiography, and 3D volumes of the left and right ventricles and left atrium were collected. Ejection fraction and left ventricular mass were measured using 3D echocardiography. Left ventricular mass was indexed to body surface area. Speckle-tracking echocardiography was used to assess global longitudinal strain of the left and right ventricles and strain of the left atrium.

RESULTS

The study population included 123 women with GDM and 246 controls. Women with GDM, compared to controls, were older (35.1 ± 5.2 vs 32.4 ± 5.5 years; P < 0.001), had higher body mass index (30.6 (interquartile range (IQR), 26.2-35.2) vs 27.5 (IQR, 24.7-30.7) kg/m² ; P < 0.001) and had higher systolic blood pressure (119.9 ± 11.2 vs 116.4 ± 12.0 mmHg; P = 0.007). In all women with GDM, there was good glycemic control. In women with GDM, compared to controls, there was lower global longitudinal strain of the left ventricle (-19.3% (IQR, -21.4 to -17.6%) vs -20.1% (IQR, -22.1 to -18.7%); P = 0.002) and right ventricle (-22.2% (IQR, -26.1 to -19.8%) vs -24.1% (IQR, -27.0 to -21.9%); P < 0.001). There was no significant difference between the groups in ejection fraction, left ventricular mass, diastolic function assessed by left atrial strain, or 3D functional indices.

CONCLUSIONS

Women with GDM, compared to women with uncomplicated pregnancy, have lower left and right ventricular myocardial deformation. Volumetric assessment using 3D echocardiography does not provide additional information about maternal cardiac function. Strain imaging is a sensitive echocardiographic modality to detect early cardiac functional changes in women with GDM. Further studies are needed to assess the pattern of deterioration of cardiac function with advancing age in women with a history of GDM. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

P5445PCSK9 and 6-month Left Ventricular Ejection Fraction after ST-segment Elevation Myocardial Infarction. A Pilot Study

Background

Proprotein convertase subtilisin/kexin type 9 (PCSK9) has emerged as a therapeutic target for reducing plasma LDL. Beyond lipid control, recent findings suggest a deleterious effect of this protein in the pathogenesis of post-myocardial infarction left ventricle remodeling and heart failure-related complications. The aim of this work was to assess the relationship between circulating PCSK9 and 6-month cardiac magnetic resonance (CMR) imaging-derived left ventricle ejection fraction (LVEF) after a first ST-segment elevation myocardial infarction (STEMI).

Methods

We prospectively evaluated 40 patients with a first STEMI treated with primary percutaneous coronary intervention (PPCI) and LVEF<50% in which PCSK9 was measured 24h post-reperfusion. All patients underwent CMR imaging 1 week and 6 months after STEMI. The association between serum PCSK9 and 6-month LVEF was evaluated by ANCOVA. The following covariates were included in the final model; 1-week CMR-derived LVEF, age, gender, 1-week CMR-infarct size, plasma suppression of tumorigenicity-2 (ST2), low density lipoprotein-cholesterol, ante treatment with statins.

Results

The mean age of the sample was 60±12 years and 33 patients (82.5%) were male. Mean 1-week and 6-month LVEF were 41±7% and 48±10%, respectively. The mean±SD of PCSK9 was 1.93±0.38 U/mL. PCSK9 values were inversely related with 6-month LVEF (r=−0.35, p=0.028). The mean values of PCSK9 were significantly higher in patients with LVEF<50% at 6 months (2.06±0.29 vs. 1.80±0.41 U/mL, p=0.028). After a multivariate adjustment, circulating PCSK9 remained significant and inversely associated with 6-month LVEF (p=0.001).

Figure 1

Conclusions

In patients with a first STEMI treated with PCCI and reduced ejection fraction, circulating PCSK9 was associated with lower LVEF at 6 months.

P6397Ejection fraction by cardiac magnetic resonance 6 months after STEMI: impact on risk stratification in chronic phase

Background

Left ventricular ejection fraction (LVEF) has traditionally been used as the cornerstone for risk stratification after STEMI and it can be accurately quantified by cine cardiovascular magnetic resonance (CMR). In recent years, the additional prognostic value of contrast CMR-derived infarct size (IS) and microvascular obstruction (MVO) soon after infarction has been demonstrated. The usefulness of CMR-derived LVEF in chronic phase for risk stratification late after STEMI is unclear.

Purpose

We hypothesized that 6-month CMR-derived LVEF can contribute in the prediction of clinical events late after STEMI beyond pre-discharge LVEF, IS and MVO.

Methods

Data were obtained from a prospective registry of reperfused STEMI patients (n=456) who were stable 6 months after infarction and in whom 1-week and 6-month CMR-derived LVEF, IS and MVO were sequentially quantified. Major adverse cardiac events (MACE) were defined as a combined clinical end-point that included death or re-admission for acute decompensated heart failure (r-ADHF), whichever occurred first, occurring after the 6-month CMR.

Results

During a mean and median follow-up of 6 years, 56 late MACE (12%, 32 deaths and 24 r-ADHF) were registered. From 1-week to 6-month, CMR parameters exhibited significant dynamic changes (p<0.001): LVEF improved (52±12 vs. 56±13%), IS decreased (21±14 vs. 18±12% of LV mass) and MVO vanished (2±4 vs. 0±1% of LV mass). At 6-month CMR, 60 patients (13%) displayed reduced LVEF (<40%), 69 (15%) mid-range LVEF (40–50%) and 327 (72%) preserved LVEF (≥50%). Late MACE rates were 28% in patients with reduced LVEF, 14% in those with mid-range LVEF and 9% in those with preserved LVEF at 6-month CMR (p<0.001 for the trend). After adjustment for baseline characteristics and for 1-week and 6-month CMR parameters, more preserved LVEF at 6 months independently associated with a lower risk of MACE late after STEMI (hazard ratio 0.96 [0.94–0.98] per 1% increase).

Conclusions

Dramatic dynamic changes occur in CMR parameters within the first months after STEMI. Reassessment of CMR-derived LVEF in chronic phase in those patients who remain stable provides relevant prognostic information for long-term risk stratification.

Acknowledgement/Funding

Funded by “Instituto de Salud Carlos III”/FEDER (PIE15/00013, PI17/01836, and CIBERCV16/11/00486 grants) and Generalitat Valenciana (GV/2018/116).

Does left ventricular shape influence clinical outcome in heart failure?

BACKGROUND

Left ventricular (LV) shape tends to become spherical in patients with dilated cardiomyopathy of diverse etiology. Clinical and echocardiographic factors which affect the degree of LV spherical distortion and the impact of altered LV shape on prognosis have not been studied adequately.

HYPOTHESIS

This study was undertaken to investigate the prognostic implications of altered LV shape on clinical outcome in dilated cardiomyopathy.

METHODS

In 112 patients with depressed LV ejection fraction (19 +/- 9%) and symptomatic heart failure, and in 10 age- and gender-matched normal controls, we performed 2-dimensional echocardiography to assess LV shape using the eccentricity index. Eccentricity index was defined as the ratio of the LV long axis to the LV transverse diameter, measured at end systole and end diastole in the apical four-chamber view. We sought univariate and multivariate clinical and echocardiographic correlates of LV shape. Further, we sought correlations between eccentricity index and clinical outcomes (death and composite outcome of death or emergent heart transplant).

RESULTS

Compared with controls, patients with cardiomyopathy had significantly lower systolic (2.04 vs. 1.56; p = 0.001) and diastolic (1.75 vs. 1.53; p = 0.003) eccentricity index, implying a more spherical LV shape. Of all clinical and echocardiographic variables tested, mitral regurgitation, right ventricular dysfunction, and increased LV mass were independently associated with spherical LV shape. At a follow-up period of 17 +/- 12 months, no correlation was found between eccentricity index and the occurrence of death or the combined endpoint of death or emergent heart transplant, in univariate or multivariate analysis.

CONCLUSIONS

In patients with dilated cardiomyopathy, the degree of spherical distortion of the LV does not correlate with prognosis.

The independent effects of left ventricular ejection fraction on short-term outcomes and resource utilization following hospitalization for heart failure

BACKGROUND

While depressed left ventricular ejection fraction is clearly associated with poor long-term outcome in heart failure (HF), the effect of ejection fraction on short-term outcomes and resource utilization following hospitalization for HF remains unclear.

HYPOTHESIS

We evaluated the independent effect of depressed ejection fraction (< or = 40%) on short-term outcomes and resource utilization following hospitalization for HF.

METHODS

The study population included 443 consecutive patients hospitalized for DRG 127 (HF and shock) with known ejection fraction. For each patient, we assessed the hospitalization cost (1995 US$), length of stay, in-hospital mortality, 30-day mortality, and 30-day readmission rates.

RESULTS

Despite similar disease severity at admission, patients with ejection fraction < or = 40% (Group 1) had longer length of stay (4.0 vs. 3.7 days; p = 0.03), a tendency toward higher hospitalization cost ($3,054 vs. $2,770; p = 0.08), more readmissions for any cause (0.4 vs. 0.3; p = 0.05) and for HF (0.2 vs. 0.1; p = 0.01), but similar in-hospital (2.5 vs. 2.6%) and 30-day mortality (4.0 vs. 4.6%) compared with patients with ejection fraction > 40% (Group 2). In multivariate analyses, Group 1 patients were more likely to have higher than median hospitalization cost [odds ratio (OR) = 1.98; 95% confidence intervals (CI) = 1.02-3.91] and longer than median hospital stay (OR = 1.68; CI = 1.08-3.91); they were also more likely to be readmitted for any cause (OR = 2.07; CI = 1.15-3.78) or for HF (OR = 5.71; CI = 1.64-21.94), and they tended to have a higher 30-day incidence of death or readmission (OR = 1.65; CI = 0.96-2.84).

CONCLUSIONS

Depressed left ventricular ejection fraction is associated with higher resource utilization and readmission rates following hospitalization for HF. Greater focus on patients with depressed ejection fraction may increase cost savings from HF disease management programs.

Effect of combined aspirin and angiotensin-converting enzyme inhibitor therapy versus angiotensin-converting enzyme inhibitor therapy alone on readmission rates in heart failure

An adverse interaction between aspirin and angiotensin-converting enzyme (ACE) inhibitors is suspected in patients with heart failure, but the effect of combined therapy with these agents on hospital readmission rates is unknown. Our study found that combining aspirin with ACE inhibitors is associated with higher early readmission rates than use of ACE inhibitors alone, particularly in patients with depressed ejection fraction and in those without coronary artery disease.

The incremental prognostic importance of body fat adjusted peak oxygen consumption in chronic heart failure

OBJECTIVES

We sought to assess whether the adjustment of peak oxygen consumption (PkVO2) to lean body mass would yield a more accurate discriminator of outcomes in the chronic heart failure population.

BACKGROUND

Peak oxygen consumption is traditionally used to risk stratify patients with congestive heart failure (CHF) and to time cardiac transplantation. There is, however, considerable variability in body fat content, which represents metabolically inactive mass.

METHODS

In 225 consecutive patients with CHF, the percentage of body fat was determined by the sum of skinfolds technique. All underwent CPX using a ramping treadmill protocol. Mean follow-up duration was 18.9+/-11.3 months.

RESULTS

There were 14 cardiovascular deaths and 15 transplants. Peak oxygen consumption lean, both as a continuous variable and using a cutoff of < or =19 ml/kg/min, was a better predictor of outcome than unadjusted PkVO2 (p = 0.003 vs. 0.027 for the continuous variables and p = 0.0006 vs. 0.055 for < or =19 ml/kg/min and < or =14 ml/kg/min unadjusted body weight, respectively). Using partial correlation index R statistics, the Cox model using PkVO2 lean < or =19 ml/kg/min, in addition to age and etiology of CHF as covariates, yielded the strongest predictive relationship to the combined end point (chi-square value 24.32). Especially in the obese patients and in women, there was considerably better correlation of PkVO2 lean with outcome than the unadjusted PkVO2.

CONCLUSIONS

The adjustment of PkVO2 to lean body mass increases the prognostic value of cardiopulmonary stress testing in the evaluation of patients with chronic heart failure. The use of <19 ml O2/kg of lean body mass/min as a cutoff in PkVO2 should be used for timing transplantation, particularly in women and the obese.

Does gender bias exist in the medical management of heart failure?

INTRODUCTION

The purpose of this study was to ascertain the presence of gender bias in the medical management of heart failure, and to assess its association with the specialty of the caregiver physician.

METHODS

In 309 patients with documented left ventricular systolic dysfunction (ejection fraction <45%) and at least one hospitalization for heart failure, we assessed the frequency of use of effective medical therapy for heart failure among male (n=187) and female (n=122) patients at the time of hospital discharge. We constructed multivariate models relating patient gender and caregiver specialty to utilization of each class of medications (angiotensin-converting enzyme inhibitors, effective vasodilator therapy (i.e., angiotensin-converting enzyme inhibitors or hydralazine-nitrate therapy), diuretics, digoxin), and combination therapy (i.e., vasodilator plus diuretic plus digoxin).

RESULTS

In crude analyses, we did not find any difference in utilization of medications between male and female patients. Multivariate analyses involving adjustment for age, race, coronary artery disease, ejection fraction, and other relevant variables, revealed higher utilization of combination therapy by cardiologists in male versus female patients (adjusted odds ratios=2.07; 95%CI=1.09-3.95), and higher utilization of digoxin therapy by non-cardiologists in female versus male patients (adjusted odds ratio=5.5; 95%CI=1.4-22.2). No gender or caregiver specialty differences were seen in models relating to the other classes of medications.

CONCLUSIONS

Our findings suggest the presence of gender bias in the medical management of heart failure, and identify an interesting interaction between caregiver specialty and gender bias.

The prognostic implications of outpatient diuretic dose in heart failure

In 111 patients with left ventricular ejection fraction < or =30% who required hospitalization for heart failure, we examined the association between outpatient dose of diuretic agents and all-cause mortality. In comparison to patients who were not on treatment with diuretics prior to hospitalization, patients being treated with 'low' doses of diuretics (<80 mg/day of furosemide) and those being treated with 'high' doses of diuretics (> or =80 mg/day of furosemide) were more likely to die during follow-up after adjustment for other clinical parameters (adjusted relative risks, RR, 3.1 and 4.6).

Primary stenting in acute myocardial infarction: influence of diabetes mellitus in angiographic results and clinical outcome

BACKGROUND

The outcome of patients with diabetes after myocardial infarction (MI) has traditionally been worse than in their nondiabetic counterparts before and during the thrombolytic therapy era. Whether the fate of patients with diabetes might improve with mechanical intervention, particularly with primary stenting, has not previously been studied.

METHODS

We compared the angiographic and clinical outcome of 76 nondiabetic patients (aged 61 +/- 14 years; 66% male) and 28 patients with diabetes (aged 65 +/- 12 years; 64% male) consecutively treated with primary stenting for acute MI. Coronary Thrombolysis In Myocardial Infarction grade 3 flow was restored in 96% of diabetic and 97% of nondiabetic patients.

RESULTS

Angiographic results after stent deployment were similar in the 2 groups. At 1-month follow-up, all patients in both groups were alive. Patients with diabetes had a much higher incidence of stent thrombosis (18% vs 1%; P =.003), which accounted for the majority of the major cardiac events at 1 month (21% vs 4%; P =.009). At a mean follow-up of 315 +/- 13 days, 99% of nondiabetic and 89% of patients with diabetes were alive (P =.04). Overall freedom from a major cardiac event (death, MI, target vessel revascularization) at 315 +/- 13 day follow-up was 88% for nondiabetics and 54% for patients with diabetes (P =.0003). By multivariate analysis, diabetes mellitus was the most important predictor for development of 1-month (RR 9.89; 95% confidence interval, 1.6-30) and late major cardiovascular events (RR 8.39; 95% confidence interval, 2.93-24).

CONCLUSIONS

Primary stenting in acute MI is highly effective in restoring immediate TIMI 3 coronary flow in nondiabetic patients and patients with diabetes. This procedure may improve benefit in terms of mortality rate to both groups, particularly in patients with diabetes, compared with previous reports with thrombolytic therapy. Nevertheless, stent thrombosis and major cardiovascular events at 1 month and late follow-up are more frequent in patients with diabetes.

Efferent projection from the rostral ventrolateral medulla to the area postrema in rats

The rostral ventrolateral medulla (RVLM) is a region of the brain primarily involved in cardiovascular control. It receives information from several areas of the brainstem, among which the area postrema (AP) and the nucleus of the solitary tract (NTS). The medial subnuclei of the solitary tract (TS) project towards the RVLM, providing cardiopulmonary information, and the AP serves information about circulatory hormones. Although the efferent pathways are well known, it is not the case for the connections from the RVLM towards the AP and the NTS. The present study was designed to examine the efferent connections from the RVLM onto the dorsal structures of the medulla: quantitatively by means of anatomical techniques, and functionally by means of electrophysiological techniques. Morphologically, Biocytin or Biotinylated dextran amine microinjections into the RVLM were followed by labelling of many fibres running towards the bulbar dorsomedial structures, with some pathways lying in the AP itself, or located in its caudal vicinity. Conversely, when microinjections of Fast Blue (FB) were made into the AP, FB-labelled cells could be observed within the RVLM. Electrophysiologically, single shock stimulation carried on AP allowed identification of axonal fibres issuing from somata located into the cardiovascular neuronal pool in the RVLM. From these results, we can assume: (1) the existence of dense efferent projection from RVLM to aspects of the dorsal vagal complex, including the AP and, among this dense projection, (2) the existence of some fibres terminating in, or crossing through the AP, and identified as conveying baroreceptor-related information, in the rat.

Coronary hemodynamics in aging spontaneously hypertensive and normotensive Wistar-Kyoto rats

OBJECTIVE

To delineate hypertension-related and age-related changes in coronary hemodynamics and to assess the role of myocardial (i.e. left ventricular) hypertrophy and cardiac fibrosis in inducing progressive deterioration of coronary flow reserve associated both with hypertension and with aging.

METHODS

Systemic and coronary hemodynamics (using radionuclide-labeled microspheres), right ventricular, left ventricular, and aortic mass indexes, and ventricular hydroxyproline concentrations (an estimate of collagen) in normotensive Wistar-Kyoto and spontaneously hypertensive rats aged 22, 35, and 65 weeks were determined.

RESULTS

Spontaneously hypertensive rats of all ages had greater left ventricular and aortic masses, greater collagen concentrations in both ventricles, a lower coronary flow reserve, and greater minimal coronary vascular resistance after administration of dipyridamole than did Wistar-Kyoto rats. Despite spontaneously hypertensive rats having only left ventricular hypertrophy, coronary hemodynamics were impaired to the same extent in both ventricles. Progressive increases in myocardial collagen concentration, decreases in coronary flow reserve, and increases in minimal coronary vascular resistance were observed in rats of both strains with aging. A positive correlation and linear regression between myocardial collagen concentration and minimal vascular resistance were found for both ventricles of rats of both strains.

CONCLUSIONS

Both aging and hypertension adversely affected the coronary circulation; furthermore, these effects appeared to be additive. Cardiac fibrosis, but not hypertrophy, might play a role in progressive deterioration of coronary hemodynamics in aging and hypertension and could provide an explanation for the diastolic dysfunction encountered clinically in older patients with hypertension.

ACE inhibition reduces left ventricular mass independent of pressure without affecting coronary flow and flow reserve in spontaneously hypertensive rats

Systemic and regional (including coronary) hemodynamics were studied in spontaneously hypertensive and normotensive Wistar Kyoto rats after 3 weeks of treatment with one of the three doses of the angiotensin converting enzyme inhibitor, ramipril. The effects of respective treatments on cardiovascular mass and systemic, coronary, and regional hemodynamics (at rest, during maximal treadmill exercise, and during dipyridamole infusion) then were evaluated in conscious rats using radiomicrosphere techniques. Low-dose ramipril (10 micrograms/kg/day by gavage) neither decreased arterial pressure nor reduced cardiac mass. However, medium (100 micrograms/kg/day) and high (1 mg/kg/day) doses reduced total cardiac and left ventricular masses to the same extent in spontaneously hypertensive rats, despite a much greater fall in arterial pressure with a high dose. Resting cardiac index, and myocardial and all other organ blood flows remained unchanged in both strains. When compared with Wistar Kyoto rats, coronary circulation was impaired in untreated spontaneously hypertensive rats (ie, reduced coronary flow and flow reserve and increased minimal coronary vascular resistance during dipyridamole infusion). This remained unchanged by ramipril. Furthermore, significant (and comparable) increases in cardiac index and myocardial blood flow and decreases in coronary vascular resistance were produced by maximal treadmill exercise in both strains. This also was unaffected by ramipril. These data showed that angiotensin converting enzyme inhibition with suboptimal and optimal hypotensive doses of ramipril reversed left ventricular hypertrophy in spontaneously hypertensive rats, but coronary flow, flow reserve, and minimal coronary vascular resistance remained unchanged despite left ventricular hypertrophy reversal.

Disparate effects of ACE-inhibitors and calcium antagonists on left ventricular structure and function in essential hypertension

The present study was designed to compare the effects of angiotensin-converting enzyme (ACE) inhibitors and calcium antagonists-the two drug classes thought to be most effective in reducing left ventricular hypertrophy-on arterial pressure, left ventricular structure and function in patients with essential hypertension. After a placebo period of 4 weeks, a population of 96 patients were treated either with one of five different ACE inhibitors or one of six different calcium antagonists. Cardiac structure and function was assessed by 2D-guided M-mode echocardiography. Whereas both drug classes lowered arterial pressure to the same extent, ACE inhibitors had a more pronounced effect on posterior and septal wall thickness and left ventricular mass index than calcium antagonists. Diastolic function, as measured by peak filling rate and duration of rapid filling, improved in both treatment groups to the same extent. However, systolic performance, as assessed by midwall fractional fibre shortening, was significantly improved by ACE inhibitors only. Myocardial contractility (end-systolic wall stress/end-systolic volume index) showed no significant change in the ACE inhibitor group but decreased after treatment with calcium antagonists. We conclude that both calcium antagonists and ACE inhibitors lower arterial pressure and increase left ventricular filling to the same extent. However, compared with calcium antagonists, ACE inhibitors had a more pronounced effect on left ventricular mass and improved systolic ventricular performance in patients with essential hypertension.

Cardiovascular effects of a trandolapril/verapamil combination in patients with mild to moderate essential hypertension

The cardiovascular effects of a combination of trandolapril and verapamil were evaluated in 14 patients with mild to moderate essential hypertension. This combination therapy decreased arterial pressure mainly through a decrease in total peripheral resistance without causing an increase in heart rate or cardiac output: left ventricular mass was significantly reduced, cardiac systolic function improved, and plasma volume and renal blood flow remained unchanged.

Enalapril and losartan reduced cardiac mass and improved coronary hemodynamics in SHR

Among the multiple mechanisms postulated for the increased risk of hypertensive left ventricular hypertrophy (LVH), coronary hemodynamic alterations remain a strong possibility. This study was designed to compare the effects of treatment with an ACE inhibitor (enalapril) and an angiotensin AT1 receptor antagonist (losartan) on systemic and coronary hemodynamics and to determine whether the combination of these two renin-angiotensin system (RAS) inhibitor would be as or more effective in reducing mean arterial pressure (MAP), left ventricular (LV) mass, and improving coronary hemodynamics than either regimen alone. Thus, 23 week old spontaneously hypertensive rats (SHR) were treated (12 weeks) with tap water (C), enalapril (30 mg.kg-1.d-1), losartan (30 mg.kg-1.d-1), or their combination (15 mg.kg-1.d-1). Age-matched Wistar-Kyoto (WKY) rats served as normotensive controls. After 12 weeks, systemic and coronary hemodynamics were determined (15 microns radiolabeled microspheres) at baseline, during maximal treadmill exercise, and during maximal dilation (dipyridamole). Enalapril and losartan equally reduced MAP and LV mass in association with a decreased total peripheral resistance. The RAS combination reduced MAP and LV mass more than either drug alone. Resting cardiac index and coronary blood flow (CBF) per unit of LV mass did not differ among the groups. Although enalapril did not improve coronary flow reserve (CFR), it diminished minimal coronary vascular resistance (MCVR); losartan improved both. However, the combination was more effective than either agent alone, reaching values close to normotensive WKY controls. In conclusion, these data demonstrated significantly impaired maximal CBF, CFR, and MCVR in untreated SHR, but losartan alone and in combination with enalapril improved systemic and coronary hemodynamics more than enalapril alone.

Is maternal serum creatine kinase actually a marker for early diagnosis of ectopic pregnancy?

OBJECTIVE

Our purpose was to investigate whether serum creatine kinase (CK) levels could be used as an early marker of ectopic pregnancy. Student's t-test was used for statistical analysis.

STUDY DESIGN

In a prospective study we therefore measured serum progesterone, beta hCG and CK levels in 30 women with ectopic pregnancies, 30 women with ongoing pregnancies and 30 women with missed abortion.

RESULTS

The mean serum CK concentration for patients with an ectopic pregnancy, ongoing pregnancy, and the women with missed abortion was 81.4 +/- 66.2, 81.5 +/- 40.3, 84.8 +/- 49.3, respectively. No relationship was found between CK level and the location of the pregnancy.

CONCLUSION

Conversely to the first report of Lavie et al. (Am J Obstet Gynecol 1993; 169: 1149), our data suggest that serum CK level is not discriminative in the early diagnosis of tubal pregnancy.

Losartan reduces cardiac mass and improves coronary flow reserve in the spontaneously hypertensive rat

OBJECTIVES

To evaluate the effects of losartan administration on cardiovascular mass, systemic and coronary hemodynamics (rest, maximal treadmill exercise, and dipyridamole infusion) and on resting regional hemodynamics in conscious spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats.

RESULTS

Although losartan administration (two doses: 10 and 30 mg/kg per day for 3 weeks by gavage) reduced left ventricular mass at the higher dose in WKY rats and with both doses in SHR, only the higher dose reduced arterial pressure in SHR. Losartan administration did not affect cardiac index, myocardial or other organ flows (radiomicrosphere) at rest in both strains. Significant increases in cardiac index and coronary flow and decreases in coronary vascular resistance were observed during exercise in both strains and these responses were not affected by losartan administration. Compared with those in WKY rats, coronary flow and flow reserve (dipyridamole) were decreased and minimal coronary vascular resistance was increased in untreated SHR. Administration of a higher losartan dose increased coronary flow reserve and decreased minimal coronary vascular resistance (measured during dipyridamole infusion) in SHR.

CONCLUSIONS

These data demonstrated that losartan administration reduced left ventricular mass, a response that did not seem to be solely dependent on afterload. Furthermore, cardiac and stroke indices and coronary flow reserve were not changed in SHR during maximal treadmill exercise after hypertrophy reversal, even with the lower dose of losartan and when the ventricular afterload was similar to that of untreated SHR.

Early genes induction in spontaneously hypertensive rats left ventricle with angiotensin-converting enzyme inhibitors but not hydralazine

Spontaneously hypertensive rats were given an angiotensin-converting enzyme (ACE) inhibitor (benazepril or quinapril) or hydralazine and were left for up to 6 hr. To examine whether administration of antihypertensive agents affects expression of immediate early genes in left ventricular myocardium, groups of rats were sacrificed at 1, 3, and 6 hr after dosing; total RNA was extracted from left ventricular tissue and analyzed by blot hybridization technique using labeled probes for c-myc, c-fos, and GAPDH mRNA. All three antihypertensive agents reduced pressure similarly, and treatment with the two ACE inhibitors increased c-fos and c-myc mRNA expression in left ventriculum. By contrast, hydralazine did not increase steady-state mRNA expression of either proto-oncogene. Thus, in parallel with the pressure fall, acute administration of the ACE inhibitors induced expression of c-fos and c-myc mRNAs in the left ventricle. Since the equidepressor dose of hydralazine did not affect expression of these proto-oncogenes, this effect of ACE inhibitors is independent of their hemodynamic action.

Role of fatty acids in signal transduction: modulators and messengers

Many of the steps involved in signal transduction are regulated positively or negatively by fatty acids (FA) per se. FA have been shown to act both as modulators and messengers, particularly of signals triggered at the level of cell membranes. Enzymes and proteins of the cyclic AMP and the protein kinase C signalling pathways and those involving ion fluxes and mobilization are both activated and/or inhibited by FA. FA can also participate in a feedback control mechanism since phospholipases are themselves modulated by FA. FA, particularly arachidonic acid liberated from membrane phospholipids, are also second messengers in signal transduction, and a good example is the activation of protein kinase C by FA. FA play an important role in regulating the transmission of signals from the extracellular environment by acting as modulators and messengers within the complex intracellular network of relays.

Effect of anticoagulants in vitro on the viability of lymphocytes and content of free fatty acids in plasma

These authors attempted to test the effect of anticoagulants on lymphocytes viability by reproducing the procedure used for lymphocyte isolation for various immunologic tests in which blood specimens are allowed to stay at room temperature for 2 h before lymphocytes are isolated. Blood was obtained with three different anticoagulants i.e. heparin, citrate, and CPDA (citrate, phosphate, dextrose, and adenine). Plasma was lyophilized and extracted with ethanol. Dried ethanol extracts were suspended in medium (RPMI 1640 + 10% fetal bovine serum) and incubated with a lymphocyte cell line (MOLT-4). After 24 h of incubation the viability of cells was examined. The following death rates of the cells were observed: heparin -63 +/- 4.6% (mean +/- SEM), citrate -27 +/- 6.7%, and CPDA 6.2 +/- 0.6% (P less than 0.0005). A significant correlation was found between these results and changes in the concentrations of free fatty acids in the extracts. These results emphasize the importance of choosing the right anticoagulant when the viability of lymphocytes is obligatory.

Short tertatolol treatment does not impair the hormone and metabolic responses to exercise and hypoglycemia in diabetics

Beta-blockers can precipitate hypoglycemia and mask its warning signs. Ten male insulin-dependent, otherwise healthy diabetic patients underwent two submaximal exercise tests and two insulin-induced hypoglycemic events (0.2 u/Kg short-acting insulin IV) after six days administration of placebo followed by tertatolol, a non selective beta-blocker (5 mg once daily). Tertatolol modified neither the exercise-induced changes in blood glucose, lactate and plasma unesterified fatty acid levels, nor those of counter regulatory hormones (glucagon, growth hormone, cortisol), while blood pressure, heart rate and plasma renin activity were significantly reduced, proving that tertatolol had actually been ingested, and was active. During the insulin-induced hypoglycemia, similarly tertatolol did not modify the course of the plasma fuels and hormones. Particularly, hypoglycemia was neither deeper nor more prolonged in the presence than in the absence of tertatolol. Warning symptoms were not affected except for palpitations which were not perceived. These results suggest that tertatolol did not precipitate hypoglycemia following exercise, and did not aggravate insulin-induced hypoglycemia in short term administration, and in otherwise healthy diabetic patients.

Inflammatory competence of fetal rat: acute-phase plasma protein response of the fetus treated by turpentine in utero

Using crossed immunoelectrophoresis, immunoelectrodiffusion, autoradiography, and equilibrium binding techniques, we demonstrate that the rat fetus, directly challenged in utero at 18 days by a single subcutaneous turpentine injection, presents a complex acute-phase plasma inflammatory response. A number of fetal serum proteins, 48 h after the injection, increase in concentration by factors of about 2-5. These positive acute-phase reactants (APR) are alpha 1-acute-phase globulin (alpha 1-AP), alpha 2-macroglobulin (alpha 2-M), alpha 1-acid glycoprotein (alpha 1-AG), haptoglobin (Hp), and hemopexin (Hpx). A number of proteins decrease, behaving like negative APRs. These are albumin, alpha 1-fetoprotein (AFP), transferrin, GHR-P63, thyroxine-binding prealbumin (TBPA), and transcortin (CBG). The marked fall in concentration of two of the high-affinity hormone-binding proteins of the fetal rat, i.e., the estrophilic AFP and TBPA, induce significant decreases (by 25-40%) of the estrogen- and thyroxine-binding abilities of the fetal serum. While the plasma inflammatory response of the fetus is qualitatively similar to that of the adult, the fetal reactions are, as a rule, quantitatively weaker. The characteristics of the plasma inflammatory response of the fetus are discussed in relation to the highly dynamic state of its development.

Dynamic pattern of estradiol binding to uterine receptors of the rat. Inhibition and stimulation by unsaturated fatty acids

The binding of estradiol to uterine cytosoluble receptors from 24-day-old rats was reduced or potentiated by unsaturated fatty acids (NEFAs), depending on the concentrations of estradiol and unsaturated NEFAs. At estradiol concentrations of up to 1.5 x 10(-8) M, unsaturated NEFAs inhibited estradiol binding to the 8 S cytosol receptor. This inhibition was dose-dependent (10-70%, p less than 0.001) and a function of NEFA unsaturation. Scatchard analysis indicated that unsaturated NEFAs caused a large decrease in receptor affinity for estradiol. Polyunsaturated NEFAs had no apparent effect on estradiol binding at estradiol concentrations of 2-4 x 10(-8) M. At high estradiol concentrations (above 4 x 10(-8) M), estradiol binding was increased 130-250% (p less than 0.01) by polyunsaturated NEFAs. This increased binding was particularly associated with proteins sedimenting at 12.5 S and the 8 S binding was, in fact, reduced. Metabolic studies showed that the reduced binding in the presence of unsaturated fatty acids was correlated with a decrease in reversibly bound estradiol at low estradiol concentrations. The increase in estradiol binding at high estradiol concentrations is the result of a reduction in reversibly bound estradiol and an increase in nonorganic solvent-extractable (water-soluble) estradiol. The amounts of these water-soluble estradiol derivatives depended on both estradiol and unsaturated NEFA concentrations. 70% of the water-soluble estradiol derivatives were trichloroacetic acid-precipitable, suggesting a covalent protein-steroid link. Thus, changes in the hydrophobic fatty acid environment of the uterine cytosol estrogen receptor could modify estrogen-receptor function by altering binding site conformation and/or by inducing changes in estradiol metabolism.

Haemoglobinopathies: a pitfall in the assessment of glycosylated haemoglobin by ion-exchange chromatography

Total glycosylated haemoglobin was determined by a minicolumn ion-exchange chromatography technique (Bio-Rad) and correlated with the mean of fasting and post-prandial blood glucose values for the preceding 6 weeks. In 360 diabetic subjects, free of congenital haemoglobinopathies and other detected causes of haemoglobin A1 misinterpretation (reference diabetic group), a highly significant correlation was established between haemoglobin A1 and glucose (y = 0.54 X +4.91; r = 0.791; p less than 0.01). In 28 of the 29 patients with heterozygous haemoglobinopathies (HbS, C, D, E), the apparent haemoglobin A1 values were lower than expected according to the 95% confidence limits of the diabetic reference group. The apparent haemoglobin A1 value was above these limits in patient 29, with beta thalassaemia. Patients with inappropriate glycosylated haemoglobin values should be investigated for causes of haemoglobin A1 misinterpretation, in particular, haemoglobinopathies.

Haemoglobinopathies, malaria, and other interferences with HBA1 assessment

Total glycosylated haemoglobin (HbA1) was determined by a rapid minicolumn chromatography technique in 438 diabetic patients and correlated with the mean of fasting and post-prandial blood glucose values for the preceding six weeks. In 360 of them, free of congenital haemoglobinopathies and other detected causes of HbA1 mis-interpretation (reference group), a significant correlation was established between the HbA1 and glucose values: y = 0.54 X + 4.91; r = 791; (p less than 0.01). In 28 of the 29 patients with heterozygous haemoglobinopathies (Hb S = 17; Hb C = 8; Hb D Pundjab = 1; Hb E = 2) the apparent HbA1 values were inappropriately low. The apparent HbA1 value was above the 95% confidence limits in the 29th patient, with beta thalassaemia. In 10 out of 14 diabetics with recurrent hypoglycemic attacks, the HbA1 value was lower than the 95% confidence limits of expected values. Out of 21 diabetics with a shortened red cell lifespan (occult blood losses: 10; haemolysis: 11) 15 displayed a lower than expected HbA1 value. Among these was a diabetic patient with malaria and severe anaemia. Out of 14 diabetics with severe chronic renal failure only 3 presented with apparent HbA1 values above the 95% confidence limits.

Early released lipid-soluble cardiodepressant factor and elevated oestrogenic substances in human septic shock

A cardiodepressant factor (CDF) able to decrease contractile activity of cultured rat heart cells was determined to be located in the lipid-soluble fraction of sera from men in septic shock. This heat-stable CDF has a molecular weight under 1000. Repeated fractionations of sera gave evidence of an oestrone-like chromatographic behaviour. Oestrone, oestradiol and cortisol were immunologically quantified in two groups (recovery and death) of men in septic shock. All of them were elevated in sera from patients with shock. Highest levels of oestrone 4330 pmol 1(-1), (SEM +/- 851, n = 15), oestradiol 1030 pmol 1(-1), (SEM +/- 220, n = 15) and cortisol 1096 pmol 1(-1), (SEM +/- 94, n = 15), were found in patients who failed to recover from shock. However, oestrone levels were the most striking, especially in the male. This study gives evidence for a polarity relationship between the CDF and oestrone, but natural oestrone does not appear to be a direct CDF. Moreover, this study shows that radioimmunoassay of oestrone could be an important index evaluating the severeness of septic shock.

Age-dependent responses of the serum non-esterified fatty acids to adrenalectomy and ovariectomy in developing rats

We report detailed gas chromatography analyses of the non-esterified fatty acids in the sera of female rats during post-natal maturation. A marked age-dependent decrease of concentration is demonstrated for all classes of compounds. Total levels fall from about 0.8 mM at birth to about 0.25 mM, 60 days later. The decrease is most pronounced for the polyunsaturated acids, which represent 27 +/- 9% of total fatty acids at birth and 13 +/- 3% 60 days later. The effects of ovariectomy and adrenalectomy on the free fatty acid levels as a function of age are strikingly different before and after maturation. When ovariectomy is performed at 5, 9 and 15 days, the fatty acid levels respond by a significant (30-40%) decrease; when adrenalectomy is carried out at the same ages, a dramatic 3-5-fold increase of all classes of fatty acids is observed. By contrast, in older animals, both responses have virtually disappeared. Possible mechanisms underlying the age-dependent patterns and behaviour of the serum free fatty acids are briefly discussed.

Mouse alpha 1-fetoprotein and albumin. A comparison of their binding properties with estrogen and fatty acid ligands

The binding of estradiol-17 beta (E2), diethylstilbestrol (DES), and polyene fatty acids, in particular arachidonate (C20:4), to alpha 1-fetoprotein (alpha-FP) and albumin purified from mouse embryo sera was studied using equilibrium dialysis and electrophoretic techniques. E2, arachidonate, and DES all bind to alpha-FP, but with decreasing strength. E2 is a high affinity, low capacity ligand (Ka approximately 0.8 X 10(8) M-1 and approximately 0.3 sites/mol of alpha-FP at 25 degrees C); arachidonate is a weaker ligand disposing of more sites (Ka approximately 0.3 X 10(7) M-1 and 4-5 sites/mol of alpha-FP); the binding of DES is of comparatively low affinity and capacity (Ka approximately 0.2 X 10(7) M-1 and n approximately 0.7/mol of alpha-FP). In spite of different structures and equilibrium parameters, E2, DES, and arachidonate are able to compete with each other for binding to the fetoprotein. The C22:4 and C22:6 fatty acids are also efficient concentration-dependent inhibitors of E2 or DES binding. Albumin binds the fatty acids and DES, but equilibrium parameters are different from those of alpha-FP. In particular, arachidonate is a better ligand for albumin, where it interacts with at least two classes of apparent sites (Ka1 approximately 0.3 X 10(8) M-1 and n1 approximately 1; Ka2 approximately 0.2 X 10(7) M-1 and n2 approximately 30). In contrast to alpha-FP, albumin virtually does not bind E2. Also, no competition could be demonstrated between DES and fatty acid ligands for binding to albumin. None of the studied interactions, with either albumin or alpha-FP, was modified even by high doses of bilirubin. The possible functions of the various binding activities present in fetal sera in the process of growth are discussed.

Corticosterone binding by mouse sera during foetal and post-natal development

The binding properties of corticosterone binding globulin (CBG) of mouse sera have been studied by equilibrium dialysis and electrophoretic techniques, at different stages of foetal and post-natal development.

Scatchard analysis has demonstrated in all cases a single class of high affinity saturable binding sites for corticosterone. Remarkable increases of the binding capacities were observed in the foetal and pregnant sera, as compared to normal adult and immature levels. The mean values of n1M1 × g−1 of serum proteins (concentration of binding sites, n1 × moles of binding proteins M1) were 21 10−8 in 14–19 day pregnant females, 17 10−8 in the amniotic fluid, 4.2 10−8 in 14–19 day embryos, and only 0.8 10−8 in the normal adult female. Neonatal mice, aged 0–6 days exhibited no CBG activities. The association constants showed values of 2.5–4.1 108 m−1 when measured with foetal sera, and of 1.2–2.1 108 m−1 with pregnant or control adult sera and with the amniotic fluid, at 25°C. Comparative electrophoretic, thermal denaturation and competition studies with foetal and pregnant plasma CBG's are also reported.

The results are discussed in relation to the origin of CBG in the foetal serum, and also with respect to similar studies in the rat, guinea pig and man. The possible biological implications of serum steroid binding proteins in mammalian development are briefly outlined.

Calcitonin: antagonism at intestinal muscarinic receptors

The action of calcitonin was studied on the motility of isolated innervated segments of rabbit and guinea-pig intestines as well as longitudinal muscle with adherent myenteric plexus dissected from the guinea-pig ileum. Calcitonin (0.25 muM) antagonized contractile responses to acetylcholine and the cholinergic response to electrical field stimulation. This hormonal effect was relatively specific since it was not observed at nicotinic receptors or adrenoceptors, nor did calcitonin act as a local anaesthetic or directly on the contractile machinery of smooth muscle. Perivascular adrenergic and intrinsic non-adrenergic inhibitory responses also were unaffected by calcitonin. However, calcitonin did have antihistaminic properties directed against H1-receptors. The concentration of calcitonin required to achieve muscarinic antagonism in our experiments is not reached at the resting level of circulating hormone.

Isolation of two forms of rat alpha-fetoprotein and comparison of their binding parameters with estradiol-17beta

In polyacrylamide gels, highly purified rat alpha1-fetoprotein shows a molecular heterogeneity, i.e. a "slow" and a "fast" moving fraction. We have isolated by electrophoretic fractionation and subsequent elution these two forms of alpha1-fetoprotein, and we have studied comparatively the binding parameters for estradiol-17beta of whole alpha1-fetoprotein preparations and of the isolated forms. We have shown that the number of binding sites per molecule of whole alpha1-fetoprotein is always, in our experimental conditions, a fractional number, inferior to unity (0.3). Furthermore, the analysis of the binding parameters of the "two forms" of alpha1-fetoprotein allows discrimination between different classes of binding sites. For the "slow" fraction, the number of predominant binding sites per molecule of protein is close to unity (0.7-0.9), whereas for the "fast" fraction, a very low fractional value is found (0.1). The corresponding association constants are reproducibly different for the two fractions: Ka = 0.1.10(8) M-1 for the "slow" alpha1-fetoprotein, and Ka = 0.7.10(8) M-1 for the "fast" alpha1-fetoprotein. Traces of a very high affinity (10(9) M-1) minor class of binding sites are demonstrated in the "slow" fraction. These results point to the existence of a molecular population of alpha1-fetoprotein, some forms of which have a strong or very strong affinity, and some a negligible affinity, for estrogens.

The comparative specificity of 3 oestradiol-binding proteins. Rat alpha-foetoprotein, rat liver 17beta-hydroxy steroid dehydrogenase and anti-(oestradiol-6-carboxymethyloxime-bovine serum albumin) antiserum

1. The specificity of 3 oestradiol-binding proteins was studied. Two of these proteins are naturally occurring (rat alpha-foetoprotein and rat liver microsomal 17beta-hydroxy steroid dehydrogenase) and the third is an artificially induced model, anti-(oestradiol-6-carboxymethyloxime-bovine serum albumin) gamma-globulins. 2. A specific binding procedure for each protein model permitted a determination of its affinity for oestradiol and for 30 other steroids. 3. The results obtained have brought to light the different areas of the steroid molecule that are important for its recognition by each of the three proteins. The two naturally occurring proteins (alpha-foetoprotein and 17beta-hydroxy steroid dehydrogenase) recognize the edge of the steroid defined by C-4, C-6, C-8 and C-15. On the other hand, the gamma-globulins recognize the opposite edge, i.e. that defined by C-2, C-10, C-11 and C-17. 4. Diethylstilboestrol, whose structure is analogous to that of a steroid, is only recognized by the two naturally occurring proteins.