Immunofluorescence and electron microscopy of the cytoplasmic surface of the human erythrocyte membrane and its interaction with Sendai virus.

A method was developed for directly observing the inner surfaces of plasma membranes by light and electron microscopy. Human erythrocytes were attached to cover slips (glass or mica) treated with aminopropylsilane and glutaraldehyde, and then disrupted by direct application of a jet of buffer, which removed the distal portion of the cells, thus exposing the cytoplasmic surface (PS) of the flattened membranes. Antispectrin antibodies and Sendai virus particles were employed as sensitive markers for, respectively, the PS and the external surface (ES) of the membrane; their localization by immunofluorescence or electron microscopy demonstrated that the major asymmetrical features of the plasma membrane were preserved. The fusion of Sendai virus particles with cells was investigated using double-labeling immunofluorescence techniques. Virus adsorbed to the ES of cells at 4 degrees C was not accessible to fluorescein-labeled antibodies applied from the PS side. After incubation at 37 degrees C, viral antigens could be detected at the PS. These antigens, however, remained localized and did not diffuse from the site of attachment, as is usually seen in viral antigens accessible on the ES. They may therefore represent internal viral antigens not incorporated into the plasma membrane as a result of virus-cell fusion.

Echocardiography in the evaluation of systolic murmurs of unknown cause.

PURPOSE: Systolic murmurs are common, and it is important to know whether physical examination can reliably determine their cause. Therefore, we prospectively assessed the diagnostic accuracy of a cardiac examination in patients without previous echocardiography who were referred for evaluation of a systolic murmur. SUBJECTS AND METHODS: In 100 consecutive adults (mean [+/- SD] age of 58 +/- 22 years) who were referred for a systolic murmur of unknown cause, the diagnostic accuracy of the cardiac examination by cardiologists (without provision of clinical history, electrocardiogram, or chest radiograph) was compared with the results of echocardiography. RESULTS: The echocardiographic findings included a normal examination (functional murmur) in 21 patients, aortic stenosis in 29 patients, mitral regurgitation in 30 patients, left or right intraventricular pressure gradient in 11 patients, mitral valve prolapse in 11 patients, ventricular septal defect in 4 patients, hypertrophic obstructive cardiomyopathy in 3 patients, and associated aortic regurgitation in 28 patients. In 28 (35%) of the 79 patients with organic heart disease, more than one abnormality was found; combined aortic and mitral valve disease was the most frequent combination (n = 22). The sensitivity of the cardiac examination was acceptable for detecting ventricular septal defect (100% [4 of 4]), isolated mitral regurgitation (88% [26 of 36]), aortic stenosis (71% [21 of 29]), and a functional murmur (67% [14 of 21]), but not for intraventricular pressure gradients (18% [2 of 11]), aortic regurgitation (21% [6 of 28]), combined aortic and mitral valve disease (55% [6 of 11]), and mitral valve prolapse (55% [12 of 22]). In 6 patients, the degree of aortic stenosis was misjudged on the clinical examination, mainly because of a severely diminished left ventricular ejection fraction. Significant heart disease was missed completely in only 2 patients. CONCLUSION: In adults with a systolic murmur of unknown cause, a functional murmur can usually be distinguished from an organic murmur. However, the ability of the cardiac examination to assess the exact cause of the murmur is limited, especially if more than one lesion is present. Thus, echocardiography should be performed in patients with systolic murmurs of unknown cause who are suspected of having significant heart disease.

Coronary tandem lesions: effect of exercise.

Coronary vasomotion of two stenoses in series (i.e., tandem lesion) was studied in 10 patients with coronary artery disease. Percent area stenosis was 69% +/- 23% for the first (S1) lesion and 70% +/- 37% for the second (S2). Quantitative coronary arteriography was carried out at rest, during two levels of exercise (2 minutes, 75 W and 1.9 minutes, 100 W), and at 5 minutes after sublingual administration of 1.6 mg nitroglycerin. Both stenoses showed exercise-induced vasoconstriction (S1: -29%, p less than 0.01 versus rest; S2: -29%, p less than 0.01 versus rest), which was reversible after sublingual administration of nitroglycerin (S1: +15%, not significant versus rest; S2: +13%, not significant versus rest). The vessel segment between the two stenoses showed no vasomotion during exercise, whereas the pre- and poststenotic "normal" vessel segment elicited exercise-induced vasodilation. There was an inverse relationship between percent area stenosis of the second lesion and exercise-induced vasoconstriction of the first lesion (correlation coefficient = 0.84). The more severe the distal stenosis was, the less exercise-induced stenosis narrowing of the proximal lesion was observed. Thus it is concluded that coronary vasomotion of two stenoses in series is dependent on both active and passive mechanisms because both lesions show exercise-induced vasoconstriction, but vasomotion of the proximal lesion is dependent on the severity of the second one.

Influence of serum cholesterol and other coronary risk factors on vasomotion of angiographically normal coronary arteries.

BACKGROUND: It has been shown that there is impairment of the vasodilatory response to acetylcholine in patients with hypercholesterolemia and angiographically normal coronary arteries. Moreover, in patients with angiographically smooth coronary arteries, the number of coronary risk factors is associated with a loss of endothelium-dependent vasodilation. The purpose of the present analysis was to evaluate in patients with and without coronary artery disease coronary vasomotor response to dynamic exercise in angiographically normal and stenosed coronary arteries and to relate the response to serum cholesterol levels as well as to other coronary risk factors. METHODS AND RESULTS: Luminal area change during exercise (delta-ex, percent change compared with rest = 100%) was determined by biplane quantitative coronary arteriography in three groups: Group 1 consisted of 14 patients with normal total serum cholesterol of < 200 mg/100 mL; mean, 173 mg/100 mL (mean age, 51 years). Group 2 comprised 23 patients with a slightly elevated cholesterol of 200 to 250 mg/100 mL; mean, 223 mg/100 mL (mean age, 53 years). Group 3 had 24 patients with markedly elevated cholesterol of > 250 mg/100 mL; mean, 288 mg/100 mL (mean age, 54 years). Serum cholesterol levels and categorical risk factors such as positive family history, history of hypertension, smoking, obesity, and diabetes were related to exercise-induced vasomotor response. The three groups did not differ with regard to clinical characteristics, exercise work load, and hemodynamic data measured during exercise. However, delta-ex in normal vessels was significantly different between all three groups (ANOVA, P < .01): +31% (group 1), +18% (group 2), and +4% (group 3). Delta-ex in stenotic vessels did not differ between the groups: -5% (group 1), -13% (group 2), and -12% (group 3). Delta-ex of the nonstenosed vessel correlated significantly and inversely with total cholesterol, with low-density lipoprotein cholesterol, with the ratio of total to high-density lipoprotein cholesterol, and with the number of coronary risk factors present in a patient. High total cholesterol and a history of hypertension were independent risk factors for impaired coronary vasomotion. CONCLUSIONS: In patients with and without coronary artery disease, hypercholesterolemia and a history of hypertension independently impair exercise-induced coronary vasodilation in angiographically normal coronary arteries. In the stenotic vessel, vasomotion during exercise does not appear to be influenced by the actual serum cholesterol. The precise mechanism by which the impaired vasomotion of the angiographically normal coronary arteries is mediated is unknown, but a direct negative effect of hypercholesterolemia on endothelial function or early undetected atherosclerosis appears to be the most likely explanation.

Magnetic resonance myocardial first-pass perfusion imaging: parameter optimization for signal response and cardiac coverage.

Fast imaging techniques allow monitoring of contrast medium (CM) first-pass kinetics in a multislice mode. Employing shorter recovery times improves cardiac coverage during first-pass conditions, but potentially flattens signal response in the myocardium. The aim of this study was therefore to compare in patients with suspected coronary artery disease (CAD) two echo-planar imaging strategies yielding either extended cardiac coverage or optimized myocardial signal response (protocol A/B, six/four slices; preparation pulse, 60 degrees /90 degrees; delay time, 10/120 msec; readout flip angle, 10 degrees /50 degrees; respectively). In phantoms and myocardium of normal volunteers (N= 10) the CM-induced signal increase was 2.5-3 times higher with protocol B (P < 0.005) than with protocol A. For the detection of individually diseased coronary arteries (> or =1 stenosis with > or =50% diameter reduction on quantitative coronary angiography (QCA)), receiver-operator characteristics of protocol B (signal upslope in 32 sectors/heart) yielded a sensitivity/specificity of 82%/73%, which was superior to protocol A (P < 0.05, N= 14). For the overall detection of CAD, the sensitivity/specificity of protocol B was 85%/81%. An adequate signal response in the myocardium is crucial for a reliable detection of perfusion deficits during first-pass conditions. The presented protocol B detects CAD with a sensitivity and specificity similar to scintigraphic techniques.

Coronary vasomotion and coronary flow reserve during exercise.

Coronary vasomotion and coronary blood flow are important determinants of myocardial perfusion in patients with coronary artery disease. New digital angiographic techniques allow to study, not only the dimensions of a stenotic lesion (quantitative coronary arteriography), but also coronary flow reserve (parametric imaging). In a preliminary study both techniques were combined and coronary dimensions, as well as coronary flow reserve were determined in 15 patients (seven normals and eight patients with coronary artery disease) at rest, 45 s after 10 mg i.c. papaverine, during two levels of supine bicycle exercise, as well as 5 min after 1.6 mg sublingual nitroglycerin. Our results show that with modern digital subtraction techniques, not only stenosis geometry, but also coronary flow reserve can be determined at rest and during exercise conditions.

Normalization of coronary vasomotion after percutaneous transluminal coronary angioplasty?

BACKGROUND: Coronary vasomotion was evaluated at rest and during bicycle exercise in 33 patients (age, 53 +/- 7 years) with coronary artery disease. In a first group of patients (n = 15), vasomotion was studied before and 4.3 +/- 2.3 months (early) after percutaneous transluminal coronary angioplasty (PTCA), whereas in a second group (n = 18), exercise coronary arteriography was performed 30 +/- 11 months (late) after successful PTCA. Patients with restenosis (percent area stenosis greater than or equal to 75% or percent diameter stenosis greater than or equal to 50%) were excluded. METHODS AND RESULTS: Luminal areas of a normal segment and the stenotic segment were determined at rest, during supine bicycle exercise, and 5 minutes after sublingual nitrate administration by using biplane quantitative coronary arteriography. Work loads before and early after PTCA were identical in group 1 and similar late after PTCA in group 2. Percent area stenosis decreased from 86% to 36% (p less than 0.001) in group 1 and from 93% to 46% (p less than 0.001) in group 2. Normal coronary arteries showed mild vasodilation during exercise before (+3%, NS versus rest), early (+7%, NS versus rest), and late after (+10%, p less than 0.05 versus rest) PTCA. Administration of sublingual nitrate was associated with significant vasodilation of the normal vessel segment before (+27%, p less than 0.001 versus rest), early (+31%, p less than 0.001 versus rest), and late (+21%, p less than 0.001 versus rest) after PTCA. In contrast, the stenotic vessel segments showed coronary vasoconstriction during exercise before PTCA (-25%, p less than 0.001 versus rest), whereas minimal vasomotion was observed early (+2%; NS versus rest) as well as late (+5%; NS versus rest) after PTCA. Individual post-PTCA (early and late) exercise data elicited vasodilation in 19, no vasomotion in four, and vasoconstriction in 10 instances. Sublingual administration of nitrate was associated with a significant increase in minimal luminal area before (+18%, p less than 0.05 versus rest), early (+24%, p less than 0.01 versus rest), and late (+16%, p less than 0.001 versus rest) after PTCA. An inverse linear correlation was found between the percent change in minimal luminal area during peak exercise and percent area stenosis at rest (r = 0.77, p less than 0.001). CONCLUSIONS: Exercise-induced stenosis narrowing is observed before PTCA but normal vasomotion is reestablished in two thirds of all patients early and late after PTCA. In one third, an abnormal reaction to exercise (i.e., vasoconstriction) persisted after PTCA, mainly in those patients with a residual area stenosis of 50% (percent diameter stenosis of 30%) or more. Thus, PTCA appears to have a salutary effect on coronary vasomotion during exercise, which, however, remains dependent on the severity of the residual stenosis.