Safety and feasibility of dobutamine-atropine stress echocardiography in patients with ischemic left ventricular dysfunction

The aim of this study was to analyze whether left ventricular dysfunction affects the safety and feasibility of high-dose dobutamine-atropine stress echocardiography. We examined the results of the test in 318 consecutive patients who were referred for high-dose dobutamine-atropine stress echocardiography and also underwent diagnostic cardiac catheterization. Forty-four patients had a left ventricular ejection fraction of 25% or less (mean, 21%; range, 15% to 25%). In the entire group of 318 patients, no serious complications (death, myocardial infarction, or ventricular fibrillation) occurred. The overall feasibility of completing the test was excellent (97%). A trial fibrillation occurred in four patients, nonsustained ventricular tachycardia in 12, and sustained ventricular tachycardia in one. A decrease in systolic blood pressure of greater than 40 mm Hg or a peak systolic pressure of less than 80 mm Hg was present in eight cases. In the group with an ejection fraction of 25% or less, there was a higher rate of significant tachyarrhythmias (14% versus 5%; p = 0.03), whereas the feasibility of the test was slightly lower (89%; p < 0.01), but no difference for hypotension was found. By multivariate analysis, a history of tachyarrhythmias was the only predictor of stress-induced arrhythmias. Advanced left ventricular dysfunction does not represent a contraindication for dobutamine-atropine stress testing.

Improved cardiac risk stratification in major vascular surgery with dobutamine-atropine stress echocardiography

OBJECTIVES

This study sought to optimize preoperative cardiac risk stratification in a large group of consecutive candidates for vascular surgery by combining clinical risk assessment and semiquantitative dobutamine-atropine stress echocardiography.

BACKGROUND

Dobutamine-atropine stress echocardiography has been used for the prediction of perioperative cardiac risk in a small group of patients scheduled for elective major vascular surgery on the basis of the presence or absence of stress-induced regional left ventricular wall motion abnormalities.

METHODS

Clinical risk assessment and dobutamine-atropine stress echocardiography were performed in 302 consecutive patients presenting for major vascular surgery. The extent and severity of stress wall motion abnormalities and the heart rate at which they occurred, in addition to the presence of wall motion abnormalities at rest, were assessed.

RESULTS

The absence of clinical risk factors (angina, diabetes, Q waves on the electrocardiogram, symptomatic ventricular tachyarrhythmias, age > 70 years) identified a low risk group of 100 patients with a 1% cardiac event rate (unstable angina). Dobutamine-atropine stress echocardiographic findings were positive in 72 patients. Twenty-seven patients had a perioperative cardiac event (cardiac death in 5, nonfatal infarction in 12, unstable angina pectoris in 10); all 27 patients had positive stress test results (positive predictive value 38%, negative predictive value 100%). The semiquantitative assessment of the extent and severity of ischemia did not provide additional prognostic information in patients with positive test results. In contrast, the heart rate at which ischemia occurred defined a high risk group with a low ischemic threshold (38 patients with 20 events [53%]) and an intermediate risk group with a high ischemic threshold (34 patients with 7 events [21%]). All 5 patients with a fatal outcome and 8 of 12 with a nonfatal myocardial infarction were in the high risk group with a low ischemic threshold.

CONCLUSIONS

Clinical variables identify 33% of patients at very low risk for perioperative complications of vascular surgery in whom further testing is redundant. In all other candidates, dobutamine-atropine stress echocardiography is a powerful tool that identifies those patients at intermediate risk and a small group at very high risk. Risk stratification with a combination of clinical assessment and pharmacologic stress echocardiography has the potential to facilitate clinical decision making and conserve resources.

Transthoracic three-dimensional echocardiography in adult patients with congenital heart disease

OBJECTIVES

This study sought to assess both the feasibility and potential role of transthoracic three-dimensional echocardiography for the evaluation of adult patients with congenital heart disease.

BACKGROUND

The unrestricted views with depth perception provided by three-dimensional echocardiography with dynamic volume-rendered display may enhance visualization of cardiac structures and detection of abnormalities in patients with congenital heart defects.

METHODS

We studied 33 patients with various heart defects (mitral valve anomalies in 9, aortic valve anomalies in 5, subaortic membrane in 5, ventricular septal defect in 4, transposition of the great arteries in 3, tetralogy of Fallot in 2, other defects in 5). Cross-sectional images of the specific region of interest were acquired from either the parasternal or apical window with the rotational technique (2 degrees interval with electrocardiographic and respiratory gating) and postprocessed for resampling in cubic format. From these three-dimensional data sets a multitude of cut planes were selected, presented in volume-rendered dynamic display and analyzed by two observers for comparison with standard two-dimensional images to assess their additional information.

RESULTS

Three-dimensional reconstruction was possible in all patients. Structures of interest were evaluated from unusual viewpoints, providing both cardiologists and surgeons with immediate feedback. When compared with standard two-dimensional images, additional information was provided for 12 patients (36%). The mitral valve, aortoseptal continuity and interatrial septum were the structures for which three-dimensional echocardiography was most useful.

CONCLUSIONS

Transthoracic three-dimensional echocardiography is feasible and facilitates spatial recognition of the intracardiac anatomy in a significant proportion of patients and enhances diagnostic confidence of complex congenital heart disease.

The value of dipyridamole echocardiography in risk stratification before vascular surgery. A multicenter study. The EPIC (Echo Persantine International Study) Group--Subproject: Risk Stratification Before Major Vascular Surgery

PURPOSE

Patients undergoing major vascular surgery are at relatively high risk of cardiac events, and pharmacological stress echocardiography is increasingly used for peri-operative risk stratification.

PATIENTS AND METHODS

One hundred and twenty-one patients undergoing vascular surgery (age 65 +/- 7 years) were studied by dipyridamole echocardiography testing in six different centres. Of the total 136 patients, 15 were subsequently excluded because surgery was either cancelled (n = 8) or postponed pending cardiac revascularization (n = 7) because of the presence of a 'high-risk' stress echo response (identified 'a priori' as a positive dipyridamole echocardiography testing with a dipyridamole-time < 5 min and/or a peak wall motion score index > 2, upon scoring each segment from 1 = normal to 4 = dyskinetic in an 11-segment model).

RESULTS

No major complications occurred during dipyridamole echocardiography testing. Technically adequate images were obtained in all patients; however, in one patient only the low dipyridamole dose (56 mg.kg-1 over 4 min) was given to limit side effects. Of the 121 patients undergoing surgery 28 (23%) had a positive test. Peri-operative events occurred in nine patients (8%): two deaths, two myocardial infarctions, five cases of unstable angina. Sensitivity and specificity of dipyridamole echocardiography testing for predicting cardiac events were 78% and 81%, respectively, with a positive predictive value of 25% and a negative predictive value of 98%. Dipyridamole echocardiography testing effectively singled out patients with, from those without, events, but neither clinical parameters, such as Detsky score, nor baseline echo parameters, such as resting wall motion score index or ejection fraction were able to distinguish between such patients.

CONCLUSION

In conclusion, dipyridamole echocardiography testing is safe and well tolerated in patients undergoing major vascular surgery, and provides an effective pre-operative screening test for risk stratification of these patients mainly due to the extremely high negative predictive value. Stress echocardiography is a better discriminator than clinical and rest echocardiographic variables.

Quantitative angiographic measurements of isolated left anterior descending coronary artery stenosis. Correlation with exercise echocardiography and technetium-99m 2-methoxy isobutyl isonitrile single-photon emission computed tomography

OBJECTIVES

This study sought to assess the value of quantitative coronary arteriography in predicting an ischemic response at exercise echocardiography and technetium-99m 2-methoxy isobutyl isonitrile (mibi) single-photon emission computed tomography (SPECT) in patients with single-vessel disease of the left anterior descending coronary artery.

BACKGROUND

The relation between severity of coronary stenosis and ischemic response to exercise echocardiography and perfusion scintigraphy in patients with single-vessel left anterior descending coronary artery disease is not well established.

METHODS

Thirty-one patients without a previous myocardial infarction who had isolated stenosis of varying degrees in the proximal or midportion of the left anterior descending coronary artery were studied. Quantitative arteriographic analysis was used for measurements of percent diameter stenosis and minimal lumen diameter. Exercise-induced wall motion abnormalities by echocardiography and transient perfusion defects by mibi SPECT were considered a positive response. The analysis of sensitivity/specificity and receiver operating characteristic curves was applied to establish the diagnostic power of quantitative coronary arteriography to predict an ischemic response to exercise echocardiography and mibi SPECT:

RESULTS

The "best" angiographic cutoff values for predicting a positive exercise echocardiographic and scintigraphic response were similar (diameter stenosis 52%, minimal lumen diameter 1.12 mm for echocardiography; diameter stenosis 49%, minimal lumen diameter 1.20 mm for SPECT). However, the sensitivity/specificity at the cross point was slightly higher (even if not statistically significant) for echocardiography than for SPECT, both for diameter stenosis (81% vs. 67%) and minimal lumen diameter (81% vs. 74%), suggesting that quantitative coronary arteriographic measurements are more closely related to echocardiographic than scintigraphic exercise test results.

CONCLUSIONS

The functional significance of a proximal/mid-left anterior descending coronary artery stenosis measured by quantitative coronary arteriography is slightly better related to echocardiographic than scintigraphic markers of exercise-induced myocardial ischemia.

Prediction of improvement of regional left ventricular function after surgical revascularization. A comparison of low-dose dobutamine echocardiography with 201Tl single-photon emission computed tomography

BACKGROUND

Although both 201Tl scintigraphy and low-dose dobutamine echocardiography (LDDE) have been proposed as effective methods of assessing myocardial viability, their relative efficacies are unknown. The aim of the present study was to compare the two imaging techniques in the prediction of improvement of regional left ventricular (LV) function after surgical revascularization.

METHODS AND RESULTS

Thirty-eight patients with severe chronic LV dysfunction (ejection fraction < or = 40%, one or more akinetic [Ak] or severely hypokinetic [SH] segments on resting echocardiogram) who underwent uncomplicated coronary artery bypass graft surgery were studied with simultaneous dobutamine stress echocardiography and poststress reinjection 201Tl single-photon emission computed tomography (SPECT) before surgery. The Ak or SH segments were considered viable by LDDE when wall thickening improved during the infusion of 10 micrograms.kg-1 min 1 dobutamine. Scintigraphic definition of viability was the presence of normal 201Tl uptake, totally reversible defect, partially reversible defect, or moderately severe fixed defect. The postoperative improvement of dyssynergic segments was determined with a rest echocardiogram 3 months after surgery. Of 608 LV segments, 169 were classified as Ak and 51 as SH on resting preoperative echocardiography. Of these, 170 were successfully revascularized. Wall motion during LDDE improved in 33 severely dyssynergic segments and was more frequent in SH than in Ak segments (19 of 44 versus 14 of 126, P < .0001). Viability was detected by 201Tl SPECT criteria in 103 SH or Ak segments. Thirty-two of the 33 segments from LDDE responders were judged viable on 201Tl SPECT, whereas 201Tl viability was also detected in 71 of 137 segments from LDDE nonresponders. The sensitivity and the specificity for the prediction of postoperative improvement of segmental wall motion were 74% (95% confidence interval [CI], 67% to 81%) and 95% (95% CI, 92% to 98%) by LDDE and 89% (95% CI, 84% to 94%) and 48% (95% 40% to 56%) by 201Tl SPECT, respectively. Positive predictive value of LDDE was higher than that of 201Tl SPECT (85%, [95% CI, 80% to 90%] versus 33% [95% CI, 26% to 40%]). Thirty-six patients had angina before and only 1 had angina 3 months after revascularization. High-dose dobutamine echocardiography demonstrated significant reduction in stress-induced ischemia (new or worsening of preexisting wall motion abnormalities) after surgery (from 163 to 23 LV segments).

CONCLUSIONS

In patients with severe chronic LV dysfunction, LDDE is a good predictor of the improvement of dyssynergic segments after revascularization. Because 201Tl SPECT overestimates the probability of postoperative improvement of dyssynergic segments, LDDE should be the preferred imaging technique for preoperative assessment of these patients.

Three dimensional reconstruction of the heart with rotational acquisition: methods and clinical applications

Images

Precordial three-dimensional echocardiography with a rotational imaging probe: methods and initial clinical experience

We report our initial experience with a precordial hand-held transducer assembly allowing computer controlled acquisition of cardiac images for dynamic three-dimensional tissue reconstruction in adult patients. A commercially available transducer and imaging system were used and its video output interfaced with the three-dimensional reconstruction unit. For this feasibility study, 20 patients in sinus rhythm and with good image quality were examined. The dynamic motion of the valves and ventricles was visualized in three-dimensional formats as well as relationships of complex pathology. Although the acquisition time in patients in sinus rhythm is relatively short, the reconstruction time is still too long and requires an experienced and dedicated operator. However, with further developments in computer technology dynamic three-dimensional echocardiography will undoubtedly become an integral if not the principal part of our routine echocardiographic examination in the future.

Mouse oocytes inhibit plasminogen activator production by ovarian cumulus and granulosa cells

Following the preovulatory surge of gonadotropins, the compact layer of cumulus cells in the antral follicle secretes a hyaluronic acid-enriched extracellular matrix and undergoes a morphological change referred to as cumulus expansion. It has been previously shown that a soluble factor(s) produced by the oocyte is required, in combination with FSH, to promote this process. Since such matrix is sensitive to proteases we have now studied the effect of the oocyte on another gonadotropin-controlled follicle cell function, i.e., the synthesis of plasminogen activator (PA). Our data indicate that isolated cumulus cells secrete uPA in the medium and that FSH or dbcAMP increases this production. The presence of the oocyte or the oocyte-conditioned medium greatly reduces uPA synthesis induced by FSH and dbcAMP in cumulus cells by modulating the abundance of its mRNA. The ability of the mouse oocyte to produce such a factor(s) is dependent upon its stage of development, with fully grown oocytes but not growing oocytes or two-cell embryos being able to inhibit uPA synthesis. A preliminary characterization of this factor suggests that it is a heat-unstable protein with an apparent molecular weight above 100 kDa. Thus, the mouse oocytes appear to promote preovulatory matrix accumulation that occurs just prior ovulation by modulating the gonadotropin action on both the synthesis and the degradation of specific matrix component.

Ultrasonic three-dimensional reconstruction of the heart

The recent advances in ultrasound equipment, digital image acquisition, and display techniques made three-dimensional (3D) echocardiography a clinically feasible and exciting technique which allows objective analysis of structure and pathological conditions of complex geometry. In this report, different image acquisition techniques are described and compared. In our experience, with rotational scanning the acquisition of cross-sections for 3D reconstruction becomes an integral part of a routine diagnostic study, both with a multiplane transesophageal imaging transducer, and in precordial echocardiography. After digital reformatting and image processing, a volumetric data set is obtained, which allows the display of synthetic cross-sections in various orientations independent from the point of origin of the sector scan [anyplane two-dimensional (2D) imaging]. This also offers the possibility of volume quantification, without the assumption of theoretical geometrical model of the cavity. Finally, dynamic volume rendered display can be applied for the objective display of the anatomy and the complex relationship among the different structures.

Prediction of improvement of ventricular function after first acute myocardial infarction using low-dose dobutamine stress echocardiography

This study was performed to assess the prevalence of spontaneous improvement of regional left ventricular function in patients after acute myocardial infarction, and to evaluate the role of low-dose dobutamine stress echocardiography for its prediction. In 57 patients with a first acute myocardial infarction (thrombolysis, n = 27; Q-wave, n = 49), regional wall motion was evaluated with 2-dimensional echocardiography at rest, during a low-dose dobutamine stress test performed within 1 week after hospital admission, and at 3-month follow-up. Myocardial viability was considered if there was an improvement of > or = 1 grade in dyssynergic segments from rest to low-dose dobutamine infusion; recovery of regional function was defined as an improvement of > or = 1 grade between rest and follow-up echocardiograms. Wall motion score index decreased from rest to low-dose dobutamine echocardiography (1.46 +/- 0.29 to 1.39 +/- 0.30, p < 0.0001), and this change persisted at follow-up study (1.37 +/- 0.30). No differences were found between patients who did and did not undergo thrombolyis, or between those who had Q-wave and non-Q-wave infarction. At baseline echocardiography, 189 of 627 segments were dyssynergic (85 hypokinetic, 104 akinetic). Viability at low-dose dobutamine stress echocardiography was more frequent in hypokinetic than in akinetic segments (30 of 85 vs 12 of 104, odds ratio 4.18, 95% confidence interval [CI] 1.87 to 9.48).(ABSTRACT TRUNCATED AT 250 WORDS)

[Dynamic transthoracic and transesophageal tridimensional echocardiography using rotational technique. A new perspective in echocardiography]

BACKGROUND

For many years, there has been a long-standing interest in developing three-dimensional echocardiography and several approaches have been followed. However, the main interest has been centered on reconstruction of left ventricular cavity. So far, dynamic three-dimensional representation of cardiac structures has been rather disappointing.

OBJECTIVES

In this study, we describe the clinical application of dynamic three-dimensional echocardiography with a rotational imaging acquisition.

METHODS

Three-dimensional echocardiography was performed in 50 patients referred to the Echocardiographic Laboratory at the Thoraxcenter for routine standard two-dimensional echocardiography (multiplane transesophageal = 30 patients; transthoracic = 20 patients) for different reasons. For transthoracic echocardiography, patients with good quality images were selected. We used prototype ultrasound probes connected to commercially available echocardiographic equipments interfaced to the Echo-Scan system. The steering logic of the system controlled the image acquisition in a given plane, at a predetermined moment in the respiratory and heart cycles (respiratory and ECG gating). Ninety rotational (2 degree interval) sector images of the heart were collected. The images were digitized, reformatted and interpolated, yielding a three-dimensional data set. From this data set, any desired cross-section of the heart could be computed, volume rendered and displayed in motion. Different algorithms were applied and mixed to produce a shaded dynamic three-dimensional display of cardiac anatomy.

RESULTS

Acquisition of images and three-dimensional reconstructions were possible in all the patients. Both conventional and unusual projections were displayed. Thus, we were able to represent the cardiac structures from cutting planes which could not be visualized from standard transthoracic or transesophageal approaches. In particular, in patients with mitral valve prolapse and mitral stenosis the left atrial "surgical" view on the valve provided additional information on both site and extent of leaflets pathology. The presence and the degree of systolic anterior movement were seen in all the patients with hypertrophic cardiomyopathy and outflow obstruction, and the site of the leaflet involved identified.

CONCLUSIONS

Dynamic three-dimensional echocardiography is clinically feasible and has the potential to offer information unavailable with conventional two-dimensional echocardiography. Rotational scanning is the logical extension of multiplane transesophageal probe, and circumvents the limitations due to the small acoustic windows during precordial acquisition.

Prognostic value of dipyridamole sestamibi single-photon emission computed tomography and dipyridamole stress echocardiography for new cardiac events after an uncomplicated myocardial infarction

A high-dose dipyridamole stress test (0.84 mg/kg in 6 minutes) with simultaneous sestamibi single-photon emission computed tomographic (SPECT) and echocardiographic imaging was performed in 89 patients before hospital discharge after an uncomplicated myocardial infarction. The aim of this study was to determine the prognostic value of these tests for new cardiac events and to compare the relative values of SPECT and echocardiography in a postinfarction dipyridamole stress test. Two years after infarction, nine patients (10%) had died, five patients (6%) had suffered a nonfatal reinfarction, and 14 patients (16%) had been readmitted to the hospital for a revascularization procedure. Cardiac death had occurred in 5 (10%) of 48 patients with a positive SPECT versus 4 (10%) of 41 with a negative SPECT (difference not significant) and in 6 (19%) of 31 with a positive echocardiogram versus 3 (5%) of 56 with a negative echocardiogram (p = 0.05). Cardiac death or reinfarction had occurred in 8 (17%) of 48 patients with a positive SPECT versus 6 (15%) of 41 with a negative SPECT (difference not significant) and in 6 (19%) of 31 with a positive echocardiogram versus 8 (14%) of 56 with a negative echocardiogram (difference not significant). Thus the predictive value of the dipyridamole stress test for new cardiac events after an uncomplicated myocardial infarction was limited, irrespective of the method used to detect ischemia. Reversible perfusion defects were identified more frequently than new wall motion abnormalities but did not predict late events. A positive dipyridamole echocardiogram was associated with a higher late mortality rate but did not predict other cardiac events.

[Stress echocardiography: 4 years of experience at the Thoraxcenter]

In this article, we report the experience on stress echocardiography at the Thoraxcenter of Erasmus University of Rotterdam in the years 1990-1994. Different types of stress have been used in conjunction with ultrasound techniques. The results have been compared with other non-invasive methods (exercise ECG testing, myocardial perfusion scintigraphy with single photon emission computed tomography) and with coronary arteriography. Both the diagnostic and prognostic value of stress echocardiography have been assessed in different clinical situations, as in patients with chest pain and suspected or proven coronary artery disease, patients referred for percutaneous transluminal coronary angioplasty, patients referred for major non cardiac vascular surgery. After this period of validation, stress echocardiography has now a definite role in the clinical decision making for the evaluation of myocardial ischemia. The assessment of viable myocardium, especially in patients with advanced left ventricular dysfunction, is one of the major topic currently under investigation. Practical aspects of the interpretation of the tests, costs and organization of the stress echo laboratory, indications and newest research applications are also discussed.

High-resolution separation of disaccharide and oligosaccharide alditols from chondroitin sulphate, dermatan sulphate and hyaluronan using CarboPac PA1 chromatography

Recent literature indicates that specific glycosaminoglycan structures are involved in various biological processes, such as anticoagulation, growth factor activation and viral infection. The initial step in the structural analysis of glycosaminoglycans is a definitive compositional analysis of its characteristic disaccharide repeat structures. Current chromatographic or electrophoretic procedures may have limitations in analysing glycosaminoglycan samples that are in low abundance, contain novel structures that need to be further characterized, or are metabolically labelled from radioactive precursors as a result of biosynthetic experiments. This study presents a new methodology for analysing disaccharides and oligosaccharides derived from chondroitin sulphate, dermatan sulphate and hyaluronan that fulfils the above criteria. The procedure involves the separation of reduced forms of these glycoconjugates on a CarboPac PA1 column using alkaline eluants. This study adopted a strategy which uses specific enzymes to release these disaccharides from their glycosaminoglycan forms. A borohydride reduction reaction was modified to be compatible with the buffer conditions commonly used with these enzymes in order to quantitatively reduce the disaccharides to their alditol forms (thereby stabilizing them to alkaline pH). Chromatography conditions were established which separated all known disaccharide alditol structures from chondroitin sulphate, dermatan sulphate and hyaluronan with extremely high resolution in a single run. Integrated pulsed amperometry was compared to UV absorbance measurement at 232 nm as two sensitive methods for detecting these reduced disaccharides; most of them could be routinely detected in the range of 50-500 ng. Data are presented applying this method to quantify hyaluronan in a biological sample which contains approximately 5000 cells and only approximately 10 ng of hyaluronan. Additional data are presented to demonstrate that this procedure will also separate oligosaccharide alditols derived from hyaluronan.

Atropine increases the accuracy of dobutamine stress echocardiography in patients taking beta-blockers

Dobutamine-atropine stress echocardiography is used for the non-invasive diagnosis of coronary artery disease, but stress test results may be influenced by beta-blockers. The aim of this study was to assess if the addition of atropine can compensate for the presence of beta-blockers in dobutamine stress echocardiography. Twenty-six patients referred for evaluation of chest pain were studied twice, on and off metoprolol 100 mg b.i.d. (in random order sequence) with a wash-out period of at least 48 h. Dobutamine stress echocardiography was performed using up to 40 micrograms.kg-1.min-1, followed, if necessary, by the addition of atropine to achieve 85% of the age-predicted maximal heart rate, unless symptoms or markers of ischaemia appeared. Atropine was given to patients on beta-blockers more often [(22/26) vs (6/26)] than to those off beta-blockers (P < 0.001). Heart rate at every stage of the test was lower on beta-blockers. Chest pain occurred in patients on beta-blockers significantly less than in those off beta-blockers (8% vs 46%), and the addition of atropine made no significant difference (31% vs 46%). During dobutamine stress, new wall motion abnormalities occurred in three patients on beta-blockers (12%); this number increased to 15 after the addition of atropine (57%). New or worsened wall motion abnormalities occurred in 12 patients (46%) off beta-blockers with dobutamine alone and in 14 patients after adding atropine (53%).(ABSTRACT TRUNCATED AT 250 WORDS)

Oocytes preserve the ability of mouse cumulus cells in culture to synthesize hyaluronic acid and dermatan sulfate

A soluble factor(s) produced by fully grown oocytes is essential, together with follicle stimulating hormone (FSH), to stimulate in vitro hyaluronic acid (HA) synthesis by mouse cumulus cells (CCs). The stability of the response to this stimulus by CCs in culture was investigated. The data showed that preculture for 8 hr in basal medium reduced to approximately 30% the ability of CCs to synthesize HA in response to FSH or dibutyryl cyclic AMP (Bt2cAMP) and soluble oocyte factor(s). However, if CCs were precultured for the same period of time as intact cumulus cell-oocyte complexes, or in the presence of fully grown oocytes, or in medium conditioned by fully grown oocytes, their ability to synthesize HA was 75-95% preserved. In vitro stimulation of dermatan sulfate (DS) synthesis by CCs does not require oocyte factors and is induced by FSH or Bt2cAMP treatment alone. However, the preservation of such activity, like that of HA synthesis, depended on the presence of a soluble oocyte factor(s) during preculture. The presence of isolated oocytes or of oocyte-conditioned medium also prevented the spreading of CCs in culture. However, inhibiting CC spreading by culture on agar-coated plates or in serum-free medium did not preserve their HA or DS synthetic activity, thus suggesting that the two oocyte actions on CCs are independent. Growing oocytes were unable both to induce HA synthesis in freshly isolated CCs stimulated with FSH and to preserve the ability to synthesize HA and DS in 8-hr precultured CCs. The results suggest that the stability of the differentiated state of mouse CCs in vitro depends upon continued exposure to a soluble factor(s) produced by fully grown oocytes.

Effects of exogenous hyaluronic acid and serum on matrix organization and stability in the mouse cumulus cell-oocyte complex

Compact cumulus cell-oocyte complexes (COCs) isolated from preovulatory mouse follicles undergo expansion in vitro when high levels of hyaluronic acid (HA) are synthesized and organized into an extracellular matrix. We studied the effects of fetal bovine serum (FBS) and of exogenous HA and HA-oligomers on the expansion process. Maximum retention of HA in the COC matrix, and hence complete COC expansion, occurs when 1% FBS is continuously present during the first 18 h of culture. Irrespective of the culture time, HA synthesized when serum is absent is primarily in the medium, whereas HA synthesized when serum is present is primarily in the cell matrix. These findings support the hypothesis that the serum factor, identified as an inter-alpha-trypsin inhibitor by Chen et al. (Chen, L., Mao, S. J., and Larsen, W. J. (1992) J. Biol. Chem. 267, 12380-12386), is a structural component of the matrix. Addition of exogenous HA or of HA oligomers of decasaccharide size (GlcUA-GlcNAc)5 or larger effectively displaces endogenously synthesized HA from the matrix into the medium, thereby preventing COC expansion. Addition of exogenous chondroitin sulfate affects neither matrix organization nor COC expansion, thus indicating specificity of the binding of some structural component(s) to HA. Fully expanded COCs disassemble when cultured longer than 18 h, a process which occurs also in vivo and which correlates with loss of oocyte fertilizability both in vivo and in vitro. This process involves release of macromolecular HA from the matrix into the medium, with loss of 50% of the HA in the first 8 h of incubation after full expansion. The release is not facilitated when HA oligomers, long enough to prevent matrix formation, are added to the culture medium after the COCs are fully expanded. This suggests that cooperative binding to HA of either the serum factor, an endogenously synthesized factor(s), or both is required to stabilize the fully expanded COC matrix.

Simultaneous dobutamine stress echocardiography and technetium-99m isonitrile single-photon emission computed tomography in patients with suspected coronary artery disease

OBJECTIVES

The purpose of this study was to determine the relative value of dobutamine stress echocardiography and technetium-99m isonitrile single-photon emission computed tomography (mibi SPECT) in the detection of myocardial ischemia.

BACKGROUND

Stress-induced new wall motion abnormalities and transient perfusion defects are both used for the diagnosis of myocardial ischemia.

METHODS

One hundred five consecutive patients with either proved or suspected coronary artery disease, who were referred for perfusion scintigraphy, were studied by a combination of the two techniques. Both echocardiographic and mibi SPECT images were visually analyzed. Three patients were excluded from the final analysis because of unsatisfactory examinations: two with noninterpretable stress echocardiograms and one with noninterpretable mibi SPECT images. The response to stress was concordantly classified by both techniques in 68% of patients (kappa = 0.51).

RESULTS

Dobutamine stress echocardiography revealed the presence of ischemia in 38 and mibi SPECT in 45 patients (overall agreement = 74%, kappa = 0.46). The agreement was higher in patients without previous myocardial infarction (84%, kappa = 0.62). When regional analysis was performed, concordance of stress echocardiography and mibi SPECT occurred in 84% of the 306 regions (kappa = 0.45). Regional agreement was also slightly higher in patients without previous infarction (88%, kappa = 0.50). In 21 patients without previous myocardial infarction who underwent coronary angiography, the overall sensitivity of dobutamine stress echocardiography and mibi SPECT for the diagnosis of coronary artery disease (diameter stenosis > 50%) was 75% and 83%, respectively, with a specificity of 89% (eight of nine patients) for both tests.

CONCLUSIONS

Dobutamine stress echocardiography represents a reasonable alternative to dobutamine mibi SPECT for the functional assessment of patients with suspected myocardial ischemia and without previous myocardial infarction.

Pharmacological stress echocardiography in the diagnosis of coronary artery disease and myocardial ischaemia: a comparison between dobutamine and dipyridamole

The objective of this study was to relate regional wall motion abnormalities assessed by dobutamine and dipyridamole stress echocardiography to quantitative measurements of coronary artery stenoses in consecutive patients referred for coronary angiography, and to compare haemodynamic effects of and complications related to the two agents. Patients underwent stress echoes on separate days in random sequence and had coronary angiography within 3 days of stress echocardiography. Echocardiograms were assessed by two investigators unaware of the patients' coronary anatomy. Coronary angiograms were also assessed quantitatively using the computer-assisted Cardiovascular Angiography Analysis System. There were 46 consecutive patients referred for coronary angiography; 28 were using beta-antagonists. Main outcome measures were sensitivity and specificity for dobutamine and dipyridamole stress echocardiography for detection of coronary artery disease (wall motion abnormalities at rest or stress) and myocardial ischaemia (stress induced new wall motion abnormalities). Sensitivity for the detection of myocardial ischaemia was found to be 57% for dobutamine and 64% for dipyridamole. Specificities were 78% and 89% respectively. Sensitivities for detection of coronary artery disease (lesion > or = 50% diameter stenosis) was 79% for dobutamine and 82% for dipyridamole; specificities were 78% and 89% respectively. These differences between the two agents are not significant. There were no severe side effects with either agent. Mean heart rate rose significantly with both tests but was higher with dobutamine; mean systolic blood pressure rose with dobutamine and fell with dipyridamole. It was concluded that dobutamine and dipyridamole stress echocardiography have similar sensitivities and specificities for detection of myocardial ischaemia and coronary artery disease although the haemodynamic effects of the two agents are different. Both are free from serious complications.

Enhanced sensitivity for detection of coronary artery disease by addition of atropine to dobutamine stress echocardiography

Patients undergoing dobutamine stress echocardiography often take beta antagonists which limit heart rate response and sensitivity in the test for detection of coronary artery disease. The aim of this study was to assess the effect of the addition of atropine to dobutamine stress echocardiography on clinical, electrocardiographic and echocardiographic outcomes. Dobutamine stress echocardiography was performed starting at and increasing every 3 minutes with 10 micrograms/kg/min to a maximum of 40 micrograms/kg/min (stage 4), which was continued for 6 minutes. In patients not achieving 85% predicted maximal exercise heart rate and in whom the test was not judged positive on echocardiographic or electrocardiographic criteria, atropine (0.25 mg intravenously, repeated up to a maximum of 1 mg if necessary) was added and dobutamine continued for up to a further 5 minutes, or until an adequate heart rate was achieved or the test was stopped because of chest pain or electrocardiographic changes. Of 80 consecutive patients undergoing dobutamine stress echocardiography within 2 weeks of coronary angiography, 49 required atropine (group A) and 31 required only dobutamine (group B). After dobutamine alone, heart rate (mean +/- SD) was higher in group B than in group A: 129 +/- 20 vs 90 +/- 18 beats/min, p less than 0.0001; but after the addition of atropine, heart rate in group A increased to 120 +/- 20 beats/min. Overall sensitivity for the detection of coronary disease was 70%, 95% confidence interval (CI) 55 to 83%; after the addition of atropine, sensitivity for group A was 65%, 95% CI 45 to 81%; in group B, sensitivity was 81%, 95% CI 54 to 96%.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship between exercise echocardiography and perfusion single-photon emission computed tomography in patients with single-vessel coronary artery disease

The aim of this study was to assess the relative value of exercise echocardiography and perfusion single-photon emission computed tomography (SPECT) in identifying the presence and severity of coronary artery stenosis. Accordingly, 44 consecutive patients with stenosis in one vessel performed simultaneous postexercise echocardiography and perfusion SPECT (with either thallium-201 [n = 19] or 99m-Tc-methoxyisobutyl isonitrile [n = 25]) in conjunction with symptom-limited bicycle exercise testing. Positive test results were based on the presence of new or worsened exercise-induced wall motion abnormalities and transient perfusion defects, respectively. Moreover, an "ischemic" score index was derived for semiquantitative assessment of both echocardiography (with a 14-segment model of left ventricular wall on a 4-point scale) and SPECT (47-segment model on a 5-point scale). All patients underwent correlative coronary arteriography, assessed by digital caliper. Significant coronary artery disease (diameter stenosis greater than or equal to 50%) was present in 30 patients. There was a good overall concordance between the two tests in terms of result (79%); compared with patients with positive results of both tests, in the seven patients with positive SPECT and negative echocardiography the time of recording echocardiographic images was longer (p = 0.05). When analyzing patients according to the percent diameter stenosis (greater than 70%, 50% to 70%, and less than 50%) for both echocardiography and SPECT, the prevalence of an ischemic response was directly related to the severity of the coronary stenosis (p less than 0.001); moreover, a negative test result was highly predictive of a diameter coronary stenosis less than 70%.(ABSTRACT TRUNCATED AT 250 WORDS)

Localization and synthesis of hyaluronic acid in the cumulus cells and mural granulosa cells of the preovulatory follicle

Mural and cumulus granulosa cells synthesize hyaluronic acid (HA) and expand in vitro in response to follicle-stimulating hormone and a soluble factor(s) produced by fully grown oocytes. In the present study we examined HA synthesis and extracellular matrix organization by the two cell populations in vivo during the preovulatory period. After injection of human chorionic gonadotropin into pregnant mares' serum gonadotropin-primed animals, a progressive increase in HA synthesis was observed by the cumulus cell-oocyte complex (COC), and by the mural granulosa cells adjacent to the antrum (antral granulosa cells). The outermost layers of mural granulosa cells (peripheral granulosa cells) did not synthesize HA. Net HA synthesis was approximately 4 pg/cell for COCs isolated after full expansion induced either in vivo or in vitro, whereas the total HA content and cell number in the ovulated COC (approximately 11 ng HA and approximately 3000 cells per COC) were about threefold higher than for COCs expanded in vitro (approximately 4 ng HA and approximately 1000 cells per COC). The increased cell content of ovulated COCs appears to be primarily the result of inclusion of proximal mural granulosa cells which synthesize HA in response to the oocyte factor(s) and become incorporated in the expanded COC extracellular matrix mass. Media conditioned by oocytes enclosed in the cumulus cell mass (intact COCs) contained only 10-20% of the HA-stimulatory activity of media conditioned by an equal number of isolated oocytes when tested on mural granulosa cell cultures. Further, HA-stimulatory activity of media conditioned by isolated oocytes was dramatically reduced (approximately 70%) by preincubation for 5 hr with cumulus cells compared to preincubation in the absence of cells. The results suggest that differences in HA synthesis between subregions of membrana granulosa depend on a diffusion gradient of the oocyte factor(s).

Dobutamine stress echocardiography before and after coronary angioplasty

Myocardial function was assessed by stress echocardiography in 28 patients before and after successful elective coronary angioplasty. Dobutamine stress echocardiography was performed using up to 40 micrograms/kg/min, followed by the addition of atropine in 20 patients to achieve 85% of the predicted maximal exercise heart rate. The initial studies were performed 1 day before and the second ones within 3 days (mean 1.3) after angioplasty. Peak heart rates and systolic blood pressures were the same for the 2 studies. The frequency of dobutamine-induced new wall motion abnormalities decreased from 20 (71%) before to 4 (14%) after angioplasty (p less than 0.0001). Before angioplasty, wall motion score index (an indicator of left ventricular wall motion, an increase in which indicates impaired wall motion due to myocardial ischemia) increased from 1.06 at rest to 1.23 at peak stress (p less than 10(-6)), but there was no significant increase in this index in the study after angioplasty. Before angioplasty, 14 patients (50%) developed chest pain during the stress test compared with 6 (21%) after angioplasty (p = 0.05), and before angioplasty, the stress test was stopped before the target heart rate was achieved, because of symptoms, ST-segment change or severe new wall motion abnormality in 14 patients compared with 7 after angioplasty (p = 0.09). Thus, early after angioplasty there is a reduction in myocardial ischemia as assessed by dobutamine stress echocardiography.

Exercise echocardiography and single photon emission computed tomography in patients with left anterior descending coronary artery stenosis

To compare the diagnostic value of exercise echocardiography and perfusion single photon emission computed tomography (SPECT) in the detection of the presence and the severity of coronary artery disease, we studied 21 patients with isolated stenosis of different degree of the left anterior descending artery. Both echocardiography and SPECT were performed in conjunction with the same symptom-limited bicycle exercise test. Positivity of the test was based on the presence of exercise-induced wall motion abnormalities and transient perfusion defects, respectively. For both tests, an 'ischemic' score was derived, as index of extent and severity of myocardial ischemia. Coronary arteriography was evaluated by caliper. The agreement between exercise echocardiography and SPECT for the presence of coronary artery disease was 90%; the discordance was due to two patients with positive echocardiography and negative SPECT. A good correlation between ischemic wall motion and perfusion score indices was found (r = 0.78, p less than 0.0001. Moreover, the percent diameter stenosis was well correlated with both ischemic indices (r = 0.75, p less than 0.0001; r = 0.67, p less than 0.001, respectively). In patients with a positive test, the mean value of ischemic wall motion score index was higher in patients with a diameter stenosis greater than or equal to 70% than in patients with a diameter stenosis less than 70% (0.59 +/- 0.19 vs 0.29 +/- 0.12, p less than 0.01); a similar trend was found for ischemic perfusion score index (0.51 +/- 0.35 vs 0.27 +/- 0.12, ns).(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise echocardiography versus thallium-201 SPECT for assessing patients before and after PTCA

This study was designed (1) to assess the relationship between stress exercise echocardiography (echo) and 201-Tl single photon emission computed tomography (SPECT) applied simultaneously in 23 patients who were candidates to percutaneous transluminal coronary angioplasty (PTCA), (2) to assess the relationship between the development of exercise-induced wall motion abnormalities, transient perfusion defects and the severity of quantitatively assessed coronary stenoses and (3) to compare the functional improvement after PTCA by exercise echo and SPECT. Before PTCA there was an agreement of 78% between stress echo (new wall motion abnormalities) and SPECT (transient perfusion defects) results. All patients with a percentage diameter stenosis greater than 70% had a positive echo and SPECT, while they were both negative if the percentage diameter stenosis was less than 50%. In 19 patients re-studied 4 weeks after PTCA, an ischaemic response at stress echo was found in two of the 13 patients who had a positive stress echo test before PTCA, and SPECT was still positive in three of the 10 patients who had a positive SPECT study before PTCA. Echo and SPECT were concordant in 17/19 cases. It is concluded that exercise echo and 201-Tl SPECT are useful non-invasive tools for the functional assessment of patients before and after PTCA, and that they provide highly concordant results.

Dobutamine stress echocardiography: its role in the diagnosis of coronary artery disease

We have assessed the usefulness of dobutamine infusion for the diagnosis of coronary artery disease by using two-dimensional echocardiography and 12-lead electrocardiogram. Dobutamine was infused at incremental doses (up to a maximum of 40 micrograms kg-1 min-1) in 52 patients with chest pain; all the patients underwent coronary angiography; significant coronary artery disease was quantitatively defined as greater than or equal to 50% diameter stenosis. Thirty-six patients were on betablockers. The test was considered positive when new regional wall motion abnormalities appeared during dobutamine infusion. No significant side effects occurred in any patient during the test. Transient wall motion abnormalities were detected in 20 of 37 patients with coronary artery disease (sensitivity = 54%); ischaemic ST segment changes were present on ECG in nine patients (sensitivity = 24%). Dobutamine stress echocardiography was negative in 12 of 15 patients with coronary artery diameter stenosis less than 50% (specificity = 80%). Exercise electrocardiography (ECG) was performed in 35 of these 52 patients. Maximum heart rate and systolic blood pressure were significantly higher during exercise than during dobutamine stress test (127 +/- 23 vs 99 +/- 24 beats min-1, P less than 0.0001; 179 +/- 25 vs 152 +/- 30 mmHg, P less than 0.0001). The exercise ECG test was positive in 12 of the 26 patients with significant coronary artery disease (sensitivity = 46%), and dobutamine stress echocardiography in 16 (sensitivity = 62%). Dobutamine stress echocardiography test is a safe and feasible diagnostic test for the noninvasive diagnosis of coronary artery disease and can be performed in patients unable to exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

The comparative value of exercise echocardiography and 99m Tc MIBI single photon emission computed tomography in the diagnosis and localization of myocardial ischaemia

To determine the relative value of exercise two-dimensional echocardiography and 99m Tc methoxyisobutylisonitrile single photon emission computed tomography (MIBI SPECT) for the detection of myocardial ischaemia, 103 consecutive patients with either proven or suspected coronary artery disease, who were referred for perfusion scintigraphy, were studied by a combination of the two techniques during the same symptom-limited upright bicycle exercise test. Appropriate echocardiographic images were recorded both at rest and immediately post-exercise and subsequently analysed by means of digital cine loop processing. Both echocardiographic and MIBI SPECT images were visually analysed. For each technique, three different responses to exercise were defined: normal (absence of rest and exercise abnormalities); ischaemic (transient scintigraphic perfusion defects and transient wall motion abnormalities during exercise echocardiography); and fixed abnormalities (fixed scintigraphic perfusion defects; echocardiographic wall motion abnormalities at rest without worsening after exercise). To allow a valid comparison of each technique in localizing ischaemia, the left ventricle was divided into the following six major regions for both methods: anterior, posterolateral, inferior, interventricular septum (subdivided in anterior and posterior septum) and apex. Eleven of the 103 patients had to be excluded from the final analysis because of unsatisfactory examinations: seven with non-interpretable exercise echocardiograms and four with non-interpretable MIBI SPECT images. The response to exercise was concordantly classified by both techniques in 84% of patients (k = 0.78). Exercise echocardiography revealed the presence of ischaemia in 38 and MIBI SPECT in 45 patients (agreement = 77%).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of exercise echocardiography with myocardial perfusion scintigraphy for the diagnosis of coronary artery disease

The rationale of exercise echocardiography for the diagnosis of coronary artery disease is based on the detection of exercise-induced wall motion abnormalities by ultrasound. Some of the problems that had previously limited the widespread application of the test have been solved by the development of digital recording and side by side cine loop display of two-dimensional echocardiograms: thus, respiratory artifacts can be eliminated, the examination is faster, and the comparison between rest and stress images has become practical and reliable improving sensitivity. The sensitivity and specificity of exercise echocardiography vary from 70 to 100%, according to patient selection, the protocol, and the gold standard used. Few studies studied the value of exercise echocardiography as compared to the more established nuclear cardiology imaging. Data from these comparative evaluations show a strong correlation between the two techniques for identifying and localizing myocardial ischemia. With good equipment and after proper training, exercise echocardiography can provide both diagnostic and prognostic information for routine clinical care.

[The echo-dobutamine test for the diagnosis of myocardial ischemia. Study on 20 patients with normal kinetics at rest]

We have assessed the value of dobutamine stress echocardiography for the diagnosis of myocardial ischemia in 20 consecutive patients referred for chest pain, without a previous myocardial infarction and with a normal left ventricular wall motion at rest. The test was considered positive when wall motion abnormalities appeared during dobutamine infusion (from 5 to a maximum of 40 micrograms/Kg/min). The results were compared to the % diameter stenosis (%DS) quantitatively measured on coronary arteriography. "Significant" coronary artery disease was defined as greater than or equal to 50% DS. No significant side effects occurred in any patients during the test. Transient wall motion abnormalities were detected in 8 of the 12 patients with significant coronary artery disease (sensitivity = 66%) and in 1 of the 8 patients without significant coronary artery disease (specificity = 88%). All the patients with false-negative dobutamine stress echocardiography had distal stenosis or stenosis in a collateral vessel; moreover, all the patients with true-positive dobutamine stress echocardiography had proximal (7 patients) or middle (1 patient) stenosis. The results of this study show that dobutamine stress echocardiography is a safe and feasible test for the noninvasive diagnosis of myocardial ischemia.

Exercise echocardiography and technetium-99m MIBI single-photon emission computed tomography in the detection of coronary artery disease

To compare the relative diagnostic value of exercise echocardiography with perfusion technetium-99m metoxyisobutylisonitrile single-photon emission computed tomography (SPECT) in detecting coronary artery disease (CAD), 75 patients with suspected CAD but a normal electrocardiogram (ECG) at rest were included in a prospective correlative study. Both the exercise echocardiograms and SPECT studies were performed in conjunction with the same symptom-limited bicycle exercise test. The development of either a new wall motion abnormality or a reversible perfusion defect after exercise, or both, were regarded as a positive test for the exercise echocardiographic and SPECT studies, respectively. The results of these 2 diagnostic tests were compared with coronary arteriography. Exercise echocardiography identified 35 (71%) and SPECT 41 (84%, p = 0.13) of the 49 patients with significant CAD (defined as greater than 50% diameter stenosis). Twenty-five of the 26 patients (96%) without significant coronary stenosis had negative exercise echocardiographic results and 23 of 26 (88%) had negative SPECT results. Exercise-induced new wall motion abnormalities showed a good correlation with reversible perfusion defects, and the results of the 2 methods were concordant in 65 of 75 patients (agreement = 88%, kappa = 0.75 +/- 0.14). Both the diagnostic accuracy of exercise echocardiography and SPECT were significantly higher than the exercise ECG (81 vs 64%, p less than 0.02 and 88 vs 64%, p less than 0.005). The sensitivity and specificity for detecting individual diseased vessels were 60 and 95% for exercise echocardiography and 67 and 94% for SPECT.(ABSTRACT TRUNCATED AT 250 WORDS)

Hyaluronic acid synthesis by mural granulosa cells and cumulus cells in vitro is selectively stimulated by a factor produced by oocytes and by transforming growth factor-beta

In ovarian antral follicles cumulus cells (approximately 1,000/follicle) closely surround the oocyte, and mural granulosa cells (approximately 50,000/follicle) are distributed at the periphery. Previous work (Salustri, A., Yanagishita, M., and Hascall, V. C. (1990) Dev. Biol. 138, 26-32) showed that oocytes produce a factor(s) which stimulates hyaluronic acid (HA) synthesis by cumulus cells during expansion of the cumulus cell-oocyte complex. We now show that mural granulosa cells also respond in vitro to the oocyte factor(s) with greatly increased HA synthesis. As with cumulus cells, a factor(s) present in fetal calf serum is required to retain newly synthesized HA in the extracellular matrix. Unlike cumulus cells, follicle-stimulating hormone (FSH) is not required for maximal stimulation, in part because mural granulosa cells synthesize prostaglandin E2 which can substitute for FSH in promoting cumulus cell-oocyte complex expansion. Of several growth factors studied, only transforming growth factor-beta 1 (TGF-beta 1) stimulated HA synthesis in both cell types. However, the stimulation of HA synthesis by TGF-beta 1 was additive with that for the oocyte factor(s), and neutralizing antibodies to TGF-beta did not inhibit the response to the oocyte factor(s). The results indicate that the oocyte factor(s) and TGF-beta 1 are not the same and that they operate through different receptors in stimulating HA synthesis. Epidermal growth factor was able to replace FSH in amplifying the response of cumulus cells to the oocyte factor(s) and in stimulating synthesis of dermatan sulfate proteoglycans.

Mouse oocytes regulate hyaluronic acid synthesis and mucification by FSH-stimulated cumulus cells

Mucification (or expansion) of the cumulus cells surrounding the oocyte is thought to depend on the direct action of gonadotropins in stimulating production and deposition of hyaluronic acid (HA) in the extracellular matrix. We now report that the oocyte is essential for this process. Either follicle-stimulating hormone (FSH) at 1 micrograms/ml or dibutyryl cAMP at 2 mM induces mucification of intact cumulus cell-oocyte complexes (COCs) in vitro, but fails to stimulate mucification of isolated cumulus cells. HA synthesis by FSH-stimulated cumulus cells is only approximately 3.5% of the value achieved by FSH-stimulated COCs. Isolated oocytes cultured with or without FSH do not synthesize detectable amounts of HA but induce isolated cumulus cells to increase HA synthesis approximately 13-fold in cocultures with FSH. Medium conditioned by isolated oocytes for 5 hr induces nearly the same level of HA synthesis by cumulus cells under the same culture conditions. FSH also stimulates cumulus cells to increase synthesis of dermatan sulfate proteoglycans (DS-PGs) approximately 3-fold, but this stimulation does not depend upon the presence of oocytes. The results indicate that oocytes produce a soluble factor(s) essential in combination with FSH to stimulate HA, but not DS-PG, synthesis by cumulus cells in vitro and that this factor(s) acts independently or downstream from the FSH-induced formation of cAMP.

Synthesis and accumulation of hyaluronic acid and proteoglycans in the mouse cumulus cell-oocyte complex during follicle-stimulating hormone-induced mucification

In most mammalian ovaries, the cumulus cell-oocyte complex (COC) expands at the time of ovulation by depositing an extensive extracellular matrix between the cumulus cells. This phenomenon can be reproduced in vitro by culturing COCs with follicle-stimulating hormone (FSH) and serum. Biosynthesis of hyaluronic acid (HA) and proteoglycans by mouse COCs in vitro was studied using [3H]glucosamine and [35S]sulfate as metabolic precursors. Radiolabeled complex carbohydrates were analyzed by ion exchange chromatography, specific enzyme digestion followed by high performance liquid chromatography, and gel filtration. The specific activities of [3H]hexosamines in the labeled molecules were determined by measuring the incorporation of 3H and 35S into chondroitin 4-sulfate disaccharides. When COCs were stimulated with FSH, HA biosynthesis increased 20-30-fold between 3-12 h later when expansion occurs, reaching a maximum rate of approximately 780 pmol (as glucosamine)/COC/h compared with the unstimulated rate of approximately 26 pmol/COC/h. The final concentration of HA in the expanded COC was calculated to be approximately 250 micrograms/ml. The effects of dibutyryl cyclic AMP (Bt2cAMP) on COC expansion and HA synthesis were similar to those of FSH, suggesting that the effects of FSH are mediated by cAMP. However, FSH significantly decreased the specific activity of the incorporated hexosamines while Bt2cAMP did not. Serum is necessary for the accumulation of HA in the COC matrix. HA synthesis in FSH-stimulated COCs was as high or higher in the absence of serum, but most was recovered in the medium and not in the COC matrix. The molecular size of the HA was greater than 2 million dalton in either case, suggesting that the serum did not alter physical properties of HA. Stimulation of proteoglycan biosynthesis by either FSH or Bt2cAMP was less pronounced (three to four times control) than for HA and was sustained throughout an 18-h culture period. A reduction of 80% in the deposition of newly synthesized PGs in the COC matrix by 0.5 mM beta-xyloside treatment did not affect the expansion of the cumulus.

Adenosine potentiates forskolin-induced delay of meiotic resumption by mouse denuded oocytes: evidence for an oocyte surface site of adenosine action

Adenosine is present in the mouse follicular fluid and has been shown to interfere with oocyte maturation in vitro. To clarify the mechanism of adenosine action on meiotic arrest, we have characterized the synergistic action of this purine with forskolin on the meiotic resumption of mouse denuded oocytes. Forskolin delays meiotic resumption by approximately 1 hour; adenosine at concentrations ranging between 30-750 microM has no significant effect. Conversely, adenosine treatment together with forskolin produces a further delay in the resumption of meiosis. This adenosine effect is dose-dependent and mimicked by adenosine analogs like N6-phenylisopropyl adenosine (PIA), 2-chloroadensoine (2-CLA), 5'-N-ethylcarboxamide (NECA). Dipyridamole, which inhibits adenosine transport, does not prevent the meiosis-arresting synergistic effect of adenosine with forskolin. Adenosine causes a 50% increase of adenosine triphosphate (ATP) content in the oocyte. However, this increase is not directly responsible for the observed delay in oocyte maturation for the following reasons: (1) the dose response of inhibition of meiotic resumption does not correlate with the doses of adenosine producing an increase in ATP; (2) dipyridamole blocks the increase in intracellular ATP, but it has no effect on the adenosine inhibition of maturation; (3) adenosine analogs inhibit oocyte maturation but do not affect intracellular ATP levels. These results suggest that the synergism of adenosine with forskolin on meiotic arrest does not require uptake of the nucleoside nor its conversion to ATP and that the adenosine effects are exerted at the level of the oocyte plasma membrane.

[Effect of the acute administration of molsidomine in refractory congestive heart failure. A double-blind randomized non-invasive study]

The effect of vasodilator Molsidomine (M) vs placebo on left ventricular dimensions and function measured by echocardiography was evaluated in a randomized study on 23 patients (pts) with refractory congestive heart failure (R CF) (NYHA class III-IV). The pts were randomized in two groups: group A (12 pts) received M, group B received an identical appearing placebo. Adequate echocardiograms were obtained before and one hour after 2 tablets of M (4 mg) or P; left ventricular end-diastolic and end-systolic diameters (LVEDD and LVESD), mean rate of circumferential shortening and left ventricular fractional shortening were calculated on the echocardiograms obtained. At the same time mean arterial pressure (MAP) and heart rate were measured. In group A, the single-dose test induced a significant reduction in LVEDD (74.1 +/- 7.2 to 72.1 +/- 7.1 mm; p less than 0.01), in LVESD (64.4 +/- 8.4 to 61.6 +/- 7.4 mm; p less than 0.01) and in MAP (96.5 +/- 8.3 to 85.4 +/- 7.2 mmHg; p less than 0.05). No significant changes were noted in the other parameters. Moreover, changes of parameters evaluated in group A between pts with idiopathic cardiomyopathy and pts with ischemic heart disease showed no statistical differences. Thus, acute Molsidomine therapy is effective in reducing left ventricular diameters and MAP in pts with RCF without changes of echocardiographic contractility indexes.

Effect of follicle-stimulating hormone on cyclic adenosine monophosphate level and on meiotic maturation in mouse cumulus cell-enclosed oocytes cultured in vitro

We have reported that in vitro treatment with follicle-stimulating hormone (FSH) delays by about 3 h spontaneous meiotic resumption in cumulus cell-enclosed mouse oocytes. In the present paper we show that the temporary meiotic block is accompanied by a transient increase of cAMP concentration in the oocyte. In cumulus cell-oocyte complexes stimulated with 1 microgram/ml FSH, cAMP significantly increases within 1 h both in the whole complex (from a basal value of 1.9 +/- 0.2 to 169 +/- 13 fmol) and in the enclosed oocyte (from 0.9 +/- 0.2 to 2.4 +/- 0.2 fmol), then progressively decreases to basal values. Stimulation by FSH does not cause any cAMP increase in denuded oocytes. As the concentration of cAMP in the cells decreases, the percentage of oocytes escaping the meiotic block imposed by FSH increases. If the complexes are cultured in the presence of 1 microgram/ml FSH plus 1 mM isobutyl-1-methylxanthine (1BMX), cAMP concentration increases approximately 250-fold in the complex, and 10-fold in the enclosed oocyte; the level of cAMP in the oocyte drops very rapidly (50% degradation in less than 2 min) if the oocyte is then transferred to IBMX-free medium. The data are discussed in terms of the possible role of cAMP transfer from cumulus cells to the oocyte in the regulation of meiotic progression in mouse oocytes.

Granulosa cells stimulate in vitro the expansion of isolated mouse cumuli oophori: involvement of prostaglandin E2

Granulosa cells (2 X 10(6) per ml) obtained from pregnant mare's serum gonadotropin (PMSG)-primed mice induce within 24 h the expansion in vitro of cocultured mouse cumuli oophori. Experiments with conditioned media showed that the expansion-promoting action of granulosa cells is due to diffusible factor(s) released into the culture medium. Studies with prostaglandin synthetase inhibitors and direct measurements of prostaglandin E2 (PGE2) released by granulosa cells in the culture medium have also been performed. The results strongly suggest that the cumulus oophorus expansion-promoting action of granulosa cells is mediated by PGE2, and support the hypothesis (Downs and Longo, 1983) that granulosa cells might play a similar role in the mechanism of cumulus expansion in vivo. The suggestion is advanced that coculture with granulosa cells might be of help to allow physiologic expansion in culture of immature cumuli obtained from preovulatory follicles in in vitro fertilization programs.