Stage-dependent inhibition of chloroquine on Plasmodium falciparum in vitro

Morphological observation of the life cycle of the malaria parasite, Plasmodium falciparum, in highly synchronous cultures after an exposure to therapeutic concentrations of chloroquine in ring, trophozoite and schizont stages, respectively, were carried out in order to determine the influence of chloroquine on the growth of the different stages of the malarial parasites. It was found that chloroquine could not affect merozoite invasion of the erythrocytes; the ring stage was more sensitive to chloroquine than the trophozoite and schizont stages; and chloroquine in therapeutic concentrations prevented only the transformation of rings to trophozoites and could not affect the transformations of trophozoites to schizonts and schizonts to new rings. The determination of the IC50 of chloroquine showed that the IC50 of trophozoites was about 6 times as high as that of rings.

Analysis of methodology for quantifying mitral regurgitation by Doppler echocardiography

It is generally agreed that Doppler echocardiography is highly sensitive and specific for the detection of mitral regurgitation. There is more confusion about its ability to quantitate the degree of mitral regurgitation. Studies of the intensity of the Doppler signals, as well as cross sectional Doppler studies apparently can provide a straightforward, but rough estimate of the degree of regurgitation in term of atrial extent of the disturbed flow. The methods are also sensitive to methodological errors as beam direction, movement of the heart, signal/noise relationship and the size of the left atrium. Another approach to the non-invasive measurement of mitral regurgitation includes the use of Doppler echocardiography for the determination of both aortic and mitral volumetric flow. In a study of patients with mitral regurgitation, we found a close correlation between the regurgitant fraction determined by Doppler echocardiography, and the regurgitant severity determined by left ventriculography. This technique can only be used in pure mitral regurgitation, while associated atrial fibrillation, mitral stenosis, and combined aortic and mitral regurgitation make correct measurements difficult.

Detection of a ventricular-specific myosin heavy chain in adult and developing chicken heart

In the present study, a monoclonal antibody (McAb), ALD19, generated against myosin of slow tonic muscle, was shown to react with the heavy chain of ventricular myosin in the adult chicken heart. With this antibody, it was possible to detect a ventricular-specific myosin during myocardial differentiation and to show that the epitope recognized by ALD19 was present from the earliest stages of ventricular differentiation and maintained throughout development only in the ventricle. A second McAb, specific for atrial myosin heavy chain (MHC) (Gonzalez-Sanchez, A., and D. Bader, 1984, Dev. Biol., 103:151-158), was used as a control to detect an atrial-specific myosin in the caudal portion of the developing heart at Hamburger-Hamilton stage 15. It was found that the appearance of ventricular MHC predated the expression of atrial MHC by approximately 1 d in ovo and that specific MHCs were always differentially distributed. While a common primordial MHC may be present in the early heart, this study showed the tissue-specific expression of a ventricular MHC during the initial stages of heart development and its differential accumulation throughout development.

Estimation of the peak-to-peak pressure gradient in aortic stenosis by Doppler echocardiography

The present study was designed to develop a new Doppler method to estimate noninvasively the peak-to-peak pressure gradient in patients with aortic stenosis. It was carried out in two steps. In the first study, left heart catheterization data were analysed in 58 patients with aortic stenosis. The peak pressure gradient correlated highly with (r = 0.98) but overestimated significantly the peak-to-peak pressure gradient. The averaged pressure gradient (average of the peak gradient and the gradient at the peak aortic pressure) was found to approximate closely the peak-to-peak pressure gradient (r = 0.99) with a good separation between significant and insignificant aortic stenosis. The ratio of the left ventricular ejection time over the aortic pressure descending time was studied and the beginning of the late one-third systole was chosen as the point for determining the late systolic gradient by the Doppler technique. In the second study, Doppler echocardiography and cardiac catheterization were performed in 35 patients with aortic stenosis. The Doppler-determined peak pressure gradient correlated highly with catheterization-measured peak pressure gradient (r = 0.95) but overestimated significantly the peak-to-peak pressure gradient. The Doppler-determined averaged pressure gradient (average of the peak and the late systolic gradients) estimated accurately the peak-to-peak gradient (r = 0.97) with a good separation between significant and insignificant aortic stenosis. These results demonstrate the limitations of the peak pressure gradient measurement and the reliability of the Doppler-determined averaged pressure gradient for estimation of the peak-to-peak pressure gradient.

Measurement of aortic regurgitation by Doppler echocardiography

In an attempt to develop a new approach to the non-invasive measurement of aortic regurgitation, transmitral volumetric flow (MF) and left ventricular total stroke volume (SV) were measured by Doppler and cross sectional echocardiography in 23 patients without aortic valve disease (group A) and in 26 patients with aortic regurgitation (group B). The transmitral volumetric flow was obtained by multiplying the corrected mitral orifice area by the diastolic velocity integral, and the left ventricular total stroke volume was derived by subtracting the left ventricular end systolic volume from the end diastolic volume. The aortic regurgitant fraction (RF) was calculated as: RF = 1 - MF/SV. In group A there was a close agreement between the transmitral volumetric flow and the left ventricular total stroke volume, and the difference between the two measurements did not differ significantly from zero. In group B the left ventricular total stroke volume was significantly larger than the transmitral volumetric flow, and there was good agreement between the regurgitant fractions determined by Doppler echocardiography and radionuclide ventriculography. Discrepancies between the two techniques were found in patients with combined aortic and mitral regurgitation or a low angiographic left ventricular ejection fraction (less than 35%). The effective cardiac output measured by Doppler echocardiography accorded well with that measured by the Fick method. Doppler echocardiography provides a new and promising approach to the non-invasive measurement of aortic regurgitation.

Determination of the mean pressure gradient in aortic stenosis by Doppler echocardiography

Measurement of the mean pressure gradient across the stenotic aortic valve provides important information about the severity of aortic stenosis. However, determination of the mean pressure gradient by Doppler echocardiography has been difficult due to the squared relation between instantaneous velocities pressure gradients. In this study, the velocity curves in aortic stenosis were analysed mathematically to develop a new and simple method for calculating the mean pressure gradient (delta Pm) from Doppler velocity tracings. The new formula is: delta Pm = 8 V2m[Vp/(Vp + Vm)] where Vp is the peak systolic velocity and Vm the mean systolic velocity. Doppler echocardiography and cardiac catheterisation were performed in 41 patients with aortic stenosis to evaluate the accuracy of this mathematical method. There was a high correlation between the peak pressure gradients determined by Doppler technique using a modified Bernoulli equation and by catheterisation (r = 0.95, SEE = 8.58 mmHg), and the difference between the two measurements was not significant. The comparison between the mean pressure gradients determined by Doppler echocardiography using the new formula and by catheterisation yielded a high correlation (r = 0.95, SEE = 5.60 mmHg), and there was no significant difference between the two means. These results demonstrate the reliability of Doppler echocardiography for determining the mean pressure gradient in aortic stenosis using our mathematical method. Measurement of the mean pressure gradient will further enhance the usefulness of Doppler echocardiography in the non-invasive evaluation of patients with aortic stenosis.

Noninvasive quantification of the aortic valve area in aortic stenosis by Doppler echocardiography

To develop a noninvasive approach to the quantification of the stenotic aortic valve area, Doppler echocardiography and cardiac catheterisation were performed in 24 patients with pure aortic stenosis. The transmitral volumetric flow was measured by Doppler echocardiography and calculated as the product of the corrected mitral orifice area (CMA) and the diastolic velocity integral (DVI). The maximal aortic jet velocities were recorded by Doppler technique and integrated to obtain the systolic velocity integral (SVI). Assuming that the aortic and mitral volumetric flows are equal, the aortic valve area (AVA) was calculated as: AVA = CMA X DVI/SVI. Mean pressure gradient and cardiac output were measured during catheterisation and the aortic valve area was calculated by the Gorlin formula. Comparison between the aortic valve area determined by Doppler technique and catheterisation yielded a close correlation (r = 0.92, P less than 0.001), and there was no significant difference between the two measurements. Good correlations of the instantaneous pressure gradient and the stroke volume were also obtained between the two techniques (r = 0.91 and r = 0.90, respectively, P less than 0.001). These results demonstrate that our Doppler echocardiographic method provides a promising approach to the noninvasive quantification of the aortic valve area in aortic stenosis.

Determination of the mean pressure gradient in mitral stenosis by Doppler echocardiography

Measurement of the mean pressure gradient provides an important estimation of the severity of mitral stenosis. However, determination of the mean pressure gradient from Doppler recordings has been unsatisfactory using previously described methods. In this study, a new method calculating the mean pressure gradient, the integral method is described. It was developed from mathematical analysis of Doppler velocity curves. Doppler echocardiography and cardiac catheterisation were performed in 23 patients with mitral stenosis to evaluate the accuracy of three current mathematical methods of determining the mean pressure gradient. The mean pressure gradients calculated by the three methods correlated highly with that measured by catheterisation (r = 0.93). However, the mean pressure gradients calculated by the previously described mean velocity square method and the arithmetical average method underestimated significantly that measured by cardiac catheterisation. In contrast, there was no significant difference between the mean pressure gradients calculated by the integral method and measured by cardiac catheterisation. These results confirm the usefulness of Doppler echocardiography for determining the mean pressure gradient in mitral stenosis and demonstrate that among current methods, the integral method provides the most accurate calculations of the mean pressure gradient.

Measurement of mitral regurgitation by Doppler echocardiography

In an attempt to develop a new approach to the non-invasive measurement of mitral regurgitation, Doppler echocardiography and left ventriculography were performed in 20 patients without valvar heart disease (group A) and in 30 patients with pure mitral regurgitation (group B). Volumetric flows through the aortic and the mitral orifices were determined by Doppler echocardiography. Aortic flow (AF) was calculated as the product of the aortic orifice area and the systolic velocity integral. The mitral flow (MF) was calculated as the product of the corrected mitral orifice area and the diastolic velocity integral. The mitral regurgitant fraction (RF) was calculated as RF = 1 - AF/MF. In group A aortic and mitral flow were very similar and the difference between the two did not differ significantly from zero. In group B the mitral flow was significantly larger than the aortic flow. There was a good correlation (r = 0.82) between the regurgitant fraction determined by Doppler echocardiography and the regurgitant grades determined by left ventriculography. The regurgitant fraction increased significantly with each grade of severity. These results show that Doppler echocardiography can be used to give a reliable measure of both aortic and mitral flow. This technique is a new and promising approach to the non-invasive measurement of mitral regurgitation.

Avian adductor profundus muscle: characterization of a pure slow tonic region by histochemical, monoclonal antibody and peptide mapping studies

The fibre type composition of the avian adductor profundus (AP) muscle which is composed of a thick white posterior part (Post. AP) and a thin red anterior part (Ant. AP) was investigated. Using the histochemical ATPase technique, monoclonal antibody analysis of myosin and C-protein isoforms, and electrophoretic and peptide mapping analyses of myosin, we have established that the Post. AP is composed of essentially pure slow tonic fibres similar to those of the anterior latissimus dorsi muscle (ALD). The Ant. AP, on the other hand, is shown to contain a mixture of slow and fast fibres, the latter giving immunocytochemical reactions atypical of the fast fibres. The larger size of the Post. AP in comparison with the ALD muscle should provide significantly more tissue for biochemical studies of tonic fibres than was previously available.