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.

Doppler echocardiographic measurement of cardiac output using the mitral orifice method

Cardiac output was determined in 20 patients with various cardiac conditions by measuring the cross sectional area of the mitral orifice by echocardiography and the transmitral flow by the Doppler technique. Cardiac output was calculated by multiplying the corrected mitral orifice area by the maximum diastolic velocity integral recorded by the pulsed mode. The results were compared with that obtained by the Fick method. The correlation for cardiac output by the two techniques was high in the whole group, particularly in patients without mitral regurgitation. There was also a good correlation for stroke volume determined by the two methods. Cardiac output was significantly overestimated by the continuous mode and in patients with mitral regurgitation. These results show that the mitral orifice method provides a new and reliable approach to the non-invasive measurement of cardiac output.

A freeze-fracture study of postembryonic differentiation of latissimus dorsi muscles of the chicken

The differentiation of fiber type characteristics in the anterior (ALD) and posterior (PLD) latissimus dorsi muscles is examined by the freeze-fracture technique in 1-, 7- and 30-day-old chicks. Several characteristics of plasma membrane (caveolae, rectilinear arrays, intramembranous particles) and sarcoplasmic reticulum which show fiber type differences in the adult ALD and PLD muscles are compared in the developmental stages. The caveolar density in the ALD fibers is about 20/microns2 at 1 day increasing to about 37/microns2 at 30 days, whereas in the PLD fibers it remains at about 20/microns2 during this period. The distribution of the caveolae in the two muscles is different from the beginning; in the ALD fibers the caveolae are distributed throughout the plasma membrane and in PLD fibers they are patterned into clusters overlying the I band regions. The density of intramembranous particles of 1-day ALD and PLD plasma membranes appears similar, but by 7 days the particle counts in the sarcolemma of the ALD muscle are about twice as numerous as those in the PLD muscle. The rectilinear arrays are virtually absent in the ALD muscle, whereas in the PLD muscle their density is about 10/microns2 at 1 day and about 20/microns2 at 7 days. Already at 1 day posthatching the SR in ALD and PLD fibers has the adult configuration, i.e., an open irregular network in ALD fibers and periodically arranged tubules with triadic expansions in the PLD fibers.(ABSTRACT TRUNCATED AT 250 WORDS)

On the solution of equations for renal counterflow models

The results of a comparative study of three discretization techniques and the solution of the resulting algebraic equations by three methods is given. For this study, a four-tube central core model with diffusion in the core was selected and equations were derived for a coherent and efficient implementation. The results of this study show that sparse matrix techniques that take the physiological connectivity of the kidney lead to significant savings in computer storage, running time and overall cost.

Ocular abnormalities in terminal deletion of the long arm of chromosome seven

Patients with distal deletions of the long arm of chromosome 7q have been reported with a variety of non-specific findings. Ocular findings have been limited to hypertelorism, palpebral fissure abnormalities, strabismus and speckled irides and no intraocular pathology with the exception of one case with unilateral optic nerve coloboma. We report a patient with terminal deletion of the long arm of chromosome 7 with marked ocular abnormalities including severe microphthalmus and large retinal colobomas.

Pertussis toxin blocks somatostatin's inhibition of stimulated cyclic AMP accumulation in anterior pituitary tumor cells

Somatostatin inhibits both forskolin and (-) isoproterenol-stimulated cyclic AMP accumulation in AtT-20 cells. Pretreatment of these cells with pertussis toxin prevents somatostatin's inhibitory effects on cyclic AMP production. This pretreatment also enhances the cyclic AMP response to forskolin and (-) isoproterenol without affecting basal cyclic AMP levels. The blockade of somatostatin's inhibitory effect was dependent both on the time of preincubation and concentration of pertussis toxin used. The rise in forskolin-stimulated cyclic AMP formation following pertussis toxin treatment preceded the blockade of somatostatin's inhibitory actions. The results suggest that somatostatin acts through an inhibitory guanine nucleotide regulatory protein to affect adenylate cyclase activity.

A review of the current impact of measles in the People's Republic of China

Before the vaccine era, epidemics of measles occurred in alternate years on the mainland of China. During epidemic years the annual incidence was as high as 1,000-5,000 cases/100,000 population, with a fatality rate of 1% to 2%. In 1965, when highly attenuated measles vaccine was developed in China, a vaccination campaign was launched throughout the country. In its early years, the immunization program was not implemented simultaneously at all places, and outbreaks that continued to occur in some areas resulted in a moderate local incidence of measles despite a decline in the overall incidence. From the late 1970s on, stronger measures were taken by local health authorities with regard to measles vaccination. By 1980 the incidence had dropped further; in that year the number of reported cases was 570,037, with 3,862 deaths. Both morbidity and mortality related to measles dropped drastically after vaccination from levels in the prevaccine era, but measles still accounts for an appreciable proportion of all cases of infectious disease.

Variability and evolutionary trends in tooth size of Gigantopithecus blacki

The measurements of Gigantopithecus blacki teeth from Liucheng are summarized and comparative statistics are calculated. Compared to the variability of tooth size in living nonhuman primates, emphasizing Pongo because of close ecological and genetic relationships, the hypothesis of a single species for Liucheng specimens is acceptable. The Liucheng sample pattern of variability in tooth size, as well as the South African robust australopithecines, differs from living nonhuman primates in the same way; the first molar is not the least variable of the molars, and the molars are relatively variable compared with the other teeth. Sexual dimorphism may be responsible for this pattern in both cases. Later G. blacki cheek teeth are significantly larger than early G. blacki. From early G. blacki to later, the expansion ratio in tooth breadth is more than in tooth length. The pattern of expansion is like that seen in South African australopithecines. Both G. blacki and South African robust Australopithecus seem to show continued adaptation to more powerful and efficient chewing. The diet of G. blacki is not known, and its reconstruction depends on estimates of body size that differ greatly.

Studies on the incorporation of membrane proteins into liposomes: --effect of "boundary lipids" on reconstitution of pig heart mitochondrial cytochrome oxidase into liposomes

The reactivation of delipidated cytochrome oxidase depends on the reformation of "annular lipids", which is tightly bounded to the enzyme molecule. In the restoration of oxidase activity, the efficiencies of phospholipids with different polar head groups decrease in this order: PS greater than DPG greater than PI greater than PA greater than PG greater than PC, PE and in the case of phosphatidylcholines with different acyl chain the order is DOPC greater than LPC greater than PC greater than DPPC, DSPC. Therefore both the polar head group and the acyl chain of phospholipids must be considered in the reactivation process. The existence and the specificity of "annular lipids" obviously influence the incorporation of cytochrome oxidase into liposomes. When acidic phospholipids are used as "annular lipids", the effectiveness of reconstitution decreases in this order: PI greater than PS greater than DPG greater than PA, PG. Divalent metallic cations would facilitate the cytochrome oxidase reconstitution, but their effects depend on the composition of "annular lipids". Using dialysis method Ca2+ and Mg2+ could facilitate the incorporation into liposomes of the enzymes having PS or DOPC as their "boundary lipids". A comparison between the effects of different metallic cations on incorporation of cytochrome oxidase also shows that, with PI as "annular lipids", the effectiveness of different cations on incorporation by incubation method decreases in this order: Ca2+ greater than Mg2+ greater than Mn2+, Sr2+ greater than La3+. Apparently, the effect of metallic cations on incorporation cannot be interpreted by considering only the neutralization of the negative charged groups on membrane protein and lipids.

Complete amino acid sequence of mung bean trypsin inhibitor

The mung bean trypsin inhibitor has been found to be microheterogeneous at N-terminal region due to the presence of several isomers. After treatment with aminopeptidase M it becomes homogeneous and is suitable for sequence determination. Based on the determination of the structures of two active fragments the complete amino acid sequence of mung bean trypsin inhibitor has been elucidated. It consists of 72 amino acid residues with 7 pairs of disulfide bonds. The results show that this inhibitor belongs to the Bowman-Birk inhibitor family.