[Atrial septal defect associated with an abnormal chamber of the right ventricle: report of a case]

A case of atrial septal defect associated with an abnormal chamber behind the right ventricle, which was heretofore undescribed, was reported. A 41-year-old woman was admitted to our hospital for the evaluation of a heart murmur. A Levine 3/6 ejection systolic murmur and a fixed splitting of the second heart sound were audible. Two-dimensional echocardiography disclosed an atrial septal defect and an abnormal chamber behind the right ventricle. This accessory chamber communicating with the right atrium was separated from the right ventricle by a membranous structure. The motion of this membrane showed a wide excursion just like that of the atrio-ventricular valve. On the M-mode echocardiogram, the anterior tricuspid leaflet and this membrane were recorded simultaneously without intervening septal echoes and this finding was very similar to that obtained in the single ventricle. Cardiac catheterization revealed that the pressure pattern in the abnormal chamber was that of the right atrium but its intracardiac electrocardiogram showed a right ventricular pattern. The complex morphological aspect of this case was confirmed by angiography and surgery. The developmental process of this very unusual anomaly is not clear, but it may be a kind of congenital anomaly related to Ebstein's anomaly.

[Grading of tricuspid regurgitation by pulsed Doppler echocardiography and liver function tests]

Recently, pulsed Doppler echocardiography has been used for the quantitative evaluation of tricuspid regurgitation (TR). However, there are some problems about the clinical significance of TR diagnosed by Doppler examination probably because of the excellent sensitivity in detecting TR. In the present study, we used liver function tests as an indicator of the visceral damage caused by TR and compared them to the severity of TR estimated by Doppler examination. Forty Doppler examinations were performed in 33 cardiac patients including seven, in which the examinations were repeated because the severity of TR changed during the clinical course. The severity of TR was classified into four grades according to the maximal extent of the regurgitant signal. Abnormal liver function was defined by the abnormalities of at least one of the following six tests: cholinesterase (CHE), gamma-GTP, leucine aminopeptidase (LAP), total bilirubin, alkaline phosphatase and GPT. Abnormal liver function tests were present in one of eight patients without TR, two of 10 with 1 + TR, four of seven with 2 + TR, seven of eight with 3 + TR, and six of seven with 4 + TR. The incidence of abnormal liver function tests increased parallel to the grade of TR and was very frequent in patients with 3 + or 4 + TR. TR diagnosed as greater than 3 + by Doppler examination is considered to have an important clinical significance and an indication of the intensive therapy.

Myocardial perfusion and left ventricular performance during exercise-induced ST-segment depression in apparently healthy subjects

Ischemic-like ST-segment depression seen during exercise in apparently healthy subjects has previously been noted, but the cause of this change is unknown. The aim of this study was to investigate the pathophysiology of this electrocardiographic change. Ten healthy subjects who developed an electrocardiographic "ischemic" pattern of ST change during treadmill exercise testing were studied. All subjects underwent both thallium-201 myocardial perfusion imaging and radionuclide angiocardiography at rest and during exercise at a time when abnormal ST changes appeared, and demonstrated a normal homogeneous pattern of thallium-201 distribution on both rest and exercise images. Overall, left ventricular ejection fraction rose from 0.60 +/- 0.06 (mean +/- SD) at rest to 0.65 +/- 0.07 with exercise. None of the subjects had regional wall motion abnormalities at rest or during exercise. These results are different from the findings observed in patients with coronary heart disease and angina pectoris in whom regional abnormalities in both perfusion and left ventricular performance have been noted during exercise. Therefore it would seem that myocardial ischemia is not likely to be a tenable explanation for the electrocardiographic "ischemic" changes in these apparently healthy subjects.

[An application of X-ray computed tomography for complex cardiac anomalies]

X-ray computed tomography (CT) was performed in two patients with complex congenital heart disease in order to assess the clinical utility in the systemic morphological diagnosis. A Somotom 2 whole body CT scanner (Siemens Co) was used, and contrast enhanced CT scanning and a dynamic CT scanning were performed in one case (Case 2).; Case 1: A 20-year-old female with double outlet right ventricle (S, D, L), pulmonary stenosis and aortic insufficiency. The CT revealed a viscero-atrial situs, ventriculoarterial relation, spatial interrelationship between the great arteries and a run of the stenotic pulmonary artery. The CT clarified spatial relationship among four cardiac chambers, ventricular septal defect and great arteries, contributing to the understanding of the complex cardiac structure. Case 2: A 26-year-old female with single ventricle (III-C solitus), pulmonary stenosis, dextroversion, left superior vena cava and WPW syndrome. The CT documented precisely a viscero-atrial situs, dextroversion, ventriculoarterial relation, spatial interrelationship between the great arteries, stenotic main and left pulmonary arteries and a dilated right pulmonary artery due to the right Blalock-Taussig operation performed 15 years before. A diagnosis of left superior vena cava could be made by CT, and its flow into coronary sinus was visualized by dynamic CT. The dynamic CT also clarified a mixing of venous and arterial blood in the common ventricle, and revealed a rudimentary ventricular septum. Thus, the CT serves useful purposes especially as examination of viscero-atrial situs, ventriculoarterial relation and spatial interrelationship between great arteries, and anomalies of the mediastinal vessels. Furthermore the relationship among four cardiac chambers, ventricular septal defect, and the pattern of blood flow were also clarified. However, the CT failed to define the state of a ventricular loop, because it could not identify ventricular muscular structures and atrioventricular valves as these move rather vigorously. The CT could not locate pulmonary stenosis, valvular or somewhere else. The CT seemed to be a promising noninvasive method in the systemic morphological diagnosis of congenital heart disease as subsidiary to echocardiographic investigation. However, in pediatric patients, it seemed considerably hard to obtain clear cardiac CT images because of the difficulty in halting respiration during procedure.

Measurements of cytoplasmic and vacuolar pH in Neurospora using nitrogen-15 nuclear magnetic resonance spectroscopy

The nitrogen-15 chemical shift of the N1 (tau)-nitrogen of 15N-labeled histidine and the half-height line widths of proton-coupled resonances of the delta- and omega,omega'-nitrogens of 15N-labeled arginine and of the alpha-nitrogens of 15N-labeled alanine and proline were measured in intact mycelia of Neurospora crassa to obtain to estimates of intracellular pH. For intracellular 15N-labeled histidine, the N1 (tau)-nitrogen chemical shift was 200.2 ppm. In vitro measurements showed that the chemical shift was slightly affected by the presence of phosphate, with which the basic amino acids may be associated in vivo. These considerations indicate a pH of 5.7-6.0 for the environment of intracellular histidine. The half-height line widths of the delta- and omega,omega'-nitrogens of [15N]arginine were 15 and 26 Hz, respectively. In vitro studies showed that these line widths also are influenced by the presence of phosphate, and, after suitable allowance for this, the line widths indicate pH 6.1-6.5 for intracellular arginine. The half-height line widths for intracellular alanine and proline were 17 and 12 Hz, respectively, which are consistent with an intracellular pH of 7.1-7.2. Pools of histidine and arginine are found principally in the vacuole of Neurospora, most likely in association with polyphosphates. Proline and alanine are cytoplasmic. The results reported here are consistent with these localizations and indicate that the vacuolar pH is 6.1 +/- 0.4 while the cytoplasmic pH is 7.15 +/- 0.10. Comparisons of these estimates with those obtained by other techniques and their implications for vacuolar function are discussed.

Effect of the nitrogen source on glutamine and alanine biosynthesis in Neurospora crassa. An in vivo 15N nuclear magnetic resonance study

The influences of different nitrogen sources on the relative rates of biosynthesis of glutamine and alanine have been studied by 15N nuclear magnetic resonance spectroscopy of intact Neurospora crassa mycelia suspensions. The rate of glutamine synthesis was fastest after growth in media deficient in free ammonium ion, whereas it was slowest following growth in media containing both glutamic acid and glutamine. The reverse trend was observed for the biosynthesis of alanine. A competition between the two biosynthetic pathways for the same substrate, glutamic acid, was found to limit the rate of alanine synthesis when glutamine synthesis was rapid. The observed in vivo rates of these reactions are compared to the reported specific activities of the enzymes catalyzing the reactions, and implications of these results for nitrogen regulation of these pathways under various physiological conditions are discussed.

Nitrogen-15 spin-lattice relaxation times of amino acids in Neurospora crassa as a probe of intracellular environment

The nitrogen-15 spin-lattice relaxation time, T1, and the nuclear Overhauser enhancement (NOE) have been measured for intracellular glutamine, alanine, and arginine in intact Neurospora crassa mycelia to probe their various intracellular environments. The relaxations of 15N gamma of glutamine, 15N alpha of alanine, and 15N omega, omega ' of arginine in N. crassa were found, on the basis of their NOE values, to be predominantly the result of 15N-H dipolar relaxation. These relaxations are therefore related to the microviscosities of the various environments and associations of the respective molecules with other cellular components that act to increase the effective molecular sizes. For 15N gamma of glutamine in the cytoplasm, the intracellular T1 (4.1 s) was only slightly shorter than that in the culture medium (4.9 s). This indicates that the microviscosity of the cytoplasm surrounding the glutamine molecules is not much greater than 1.3 cP. By contrast, for 15N omega, omega ' of arginine, which is sequestered in vacuoles containing polyphosphates, the intracellular T1 (1.1 s) was only one-fourth of that in the medium (4.6 s). In model systems, the T1 of 15N omega, omega ' in a 1 M aqueous solution of arginine containing 0.2 M pentaphosphate was 0.95 s, whereas in an isoviscous (2.8 cP) solution without pentaphosphate, the T1 was 1.8 s. These results suggest either that the vacuolar viscosity is substantially above 2.8 cP or that the omega, omega '-nitrogens of vacuolar arginine are associated with a polyanion, possibly polyphosphate. The implications of these results for the properties of the vacuolar interior are discussed in relation to the mechanism of amino acid compartmentation.

Nitrogen-15 nuclear magnetic resonance of arsanilazotyrosine-248 carboxypeptidase A and its complex with beta-phenylpropionate. Structure and dynamics in solution

Nitrogen-15 nuclear magnetic resonance has been used to study the structure of arsanilazocarboxypeptidase A and its complex with the inhibitor beta-phenylpropionate. Derivatives selectively enriched with 15N were prepared to facilitate observation of the 15N resonances. The results are consistent with the conclusions reached previously from absorption spectroscopic studies and, in addition, provide new information regarding the properties of the azoenzyme and its inhibitor complex. Direct evidence has been obtained for formation of an intramolecular complex between the catalytically essential zinc ion and azoTyr-248, and it has been possible to estimate the degree of complexation. Moreover, the zinc complex involves the distal (N beta) nitrogen of the azo linkage, whereas a model compound, tetrazolyl-N-acetyltyrosine, complexes to zinc through the proximal (N alpha) nitrogen. The 15N NMR spectra give specific information regarding the intramolecular hydrogen bonding in the azoenzyme. The free azophenol form of the azoenzyme, like that of the model compound arsanilazo-N-acetyltyrosine, exists predominantly with the tyrosine phenolic proton intramolecularly hydrogen bonded to N beta of the azo linkage to form a six-membered ring structure. A similar hydrogen bond is also present in the apoazoenzyme and in the azoenzyme-Gly + L-Tyr) complex, but not in the complex between the azoenzyme and beta-phenylpropionate. In the latter complex, there appears to be a new and strong hydrogen bond between the phenolic proton of Tyr-248 and the carboxylate group of enzyme-bound beta-phenylpropionate. Thus, azoenzyme-bound beta-phenylpropionate, but not azoenzyme-bound Gly + L-Tyr, is apparently able to compete effectively with, and displace, the azo nitrogen as the hydrogen-bond acceptor of the phenolic proton of Tyr-248.

Potentiation of toxicity and positive inotropic effect of ouabain by furosemide in guinea pig heart

The present study was undertaken to elucidate the potentiation by furosemide of toxicity and positive inotropic effect of ouabain in guinea pigs. Arrhythmogenic responses to ouabain as well as the lowering of its lethal dose were potentiated by pretreatment with furosemide in guinea pigs. The potentiation of ouabain toxicity after furosemide administration was inhibited by pretreatment with potassium sparing diuretic, prorenoate. Furosemide-induced potentiations of contractile force and arrhythmogenic effect of ouabain were also observed in isolated guinea pig papillary muscle. However after pretreatment with furosemide, ouabain produced arrhythmias without any significant changes in either left ventricular or subcellular fractions binding of 3H-ouabain in guinea pigs. These findings suggest that furosemide-induced potentiation of ouabain toxicity is at least in part associated with the decreased intracellular potassium content of guinea pig heart. It was also demonstrated that the positive inotropic action induced by subtoxic dose of ouabain was potentiated by furosemide in guinea pig papillary muscle preparation.

Conditions for "coronary steal" caused by coronary vasodilator in man

This study was undertaken to assess the conditions necessary to cause the "coronary steal" phenomenon in human subjects. We studied 42 patients (36 males, 6 females, ages 27--70 years) with known or suspected coronary artery diseases using continuous monitoring of the changes in blood pressure and electrocardiogram, thallium-201 myocardial imaging and selective coronary arteriography. Dipyridamole in a dose of 0.4 mg/Kg was given as an intravenous infusion for 4 min and thallium-201 was injected at the 4th minute after completion of the dipyridamole infusion. None of the 20 patients without significant coronary artery disease complained of anginal chest pain or showed ischemic S-T segment depression. Dipyridamole images showed no perfusion abnormalities in 17 of the 20 patients. On the other hand, in 4 of the 22 patients with significant coronary artery disease, anginal chest pain accompanied with S-T segment depression occurred after the dipyridamole infusion. Dipyridamole images showed perfusion abnormalities in 18 of the 22 patients. The 4 patients who experienced an anginal attack had 3 vessel disease on the coronary arteriogram and showed regional perfusion defects on scintigrams corresponding to the regions receiving collaterals. Before the onset of pain, the double product (heart rate X systolic arterial pressure) was unchanged significantly but there was a reduction in the systemic blood pressure. The overall data exhibit the following conditions under which attacks of angina pectoris are induced by dipyridamole: 1) the presence of multiple vessel disease, 2) a fall in systemic blood pressure, and 3) regional malperfusion caused by dipyridamole.

15N NMR studies of nitrogen metabolism in intact mycelia of Neurospora crassa

Suspensions of intact mycelia of Neurospora crassa grown in medium containing 15NH4Cl have been found to give well-resolved 15N nuclear magnetic resonance spectra for metabolites that play crucial roles in intermediary nitrogen metabolism. These include the amide nitrogen of glutamine, the alpha-amino nitrogens of glutamate and other amino acids, the guanidino nitrogens of arginine, the ureido nitrogen of citrulline, the side-chain nitrogens of ornithine or lysine, or both, and uridine diphosphates. The turnover time of glutamine in vivo was estimated to be less than 1 hr by using nuclear magnetic resonance spectroscopy in conjunction with tracer methodologies. Applications of these techniques to the study of nitrogen metabolism are discussed.