[Digoxin intoxication in newborns correlation with digoxin plasma concentration (author's transl)]

During childhood digitalis glycosides are most frequently used during the newborn period. Within two years, we found evidence of digoxin intoxication in eight newborns. This was suspected when specific electrocardiographic signs developed under digoxin treatment and disappeared either after discontinuation of digoxin alone, or in combination with specific treatment. These eight newborns had plasma digoxin concentrations of 5 ng/ml or more, while the concentrations in unaffected newborns averaged 2.4 ng/ml (premature newborns) and 2.2 ng/ml, (mature newborns). The clinical and pathophysiological features of digoxin intoxication specific to the newborn period are discussed. Despite certain limitations it seems reasonable to check plasma digoxin concentrations during the newborn period, since clinical and electrocardiographic manifestations of a digoxin intoxication are frequently unspecific at this age. A digoxin intoxication is very likely with plasma digoxin concentrations of 5 ng/ml or more, but unlikely with concentrations below 3 ng/ml.

[Plasma digoxin concentration in different age groups (author's transl)]

Plasma digoxin concentration during maintenance therapy with digoxin was determined in premature and mature newborns, infants, children and adults. The plasma digoxin concentration of newborns was significantly higher than in adults; in addition, in the group of premature newborns it also was higher than in infants and children. These differences in plasma digoxin concentrations may be explained by differences in dose, volume of distribution and excretion rate of digoxin in the various age groups.

Herpesvirus morphology: visualization of a structural subunit

The presence of spontaneously disrupted cytomegalovirus capsids has made it possible to visualize a subunit within the herpesvirus capsomere. The pattern resolved agreed well with the theoretical net based on the concept of a structural subunit at each apex of the hexon.

Heterogeneity in nucleosome spacing

The organization of spacer DNA connecting 160 base-pair cores of bovine thymus polynucleosomes has been studied by a combination of biochemical and electron microscopic techniques. The results reveal that a major fraction of chromatin consists of a spectrum of repeating units; these differ from each other by up to 20 base-pairs due to variation in spacer DNA length. Those polynucleosomes which have larger spacer DNA lengths are processed by micrococcal nuclease to mononucleosomes more rapidly than those organized with shorter spacers. Although a distribution of spacer DNA lengths exists, a significant proportion of spacers that are nearest neighbors share common DNA lengths. These findings imply that functional roles may be related to the manners in which spacers are organized along chromatin fibers.

Serum concentration and serum half-life of digoxin in premature and mature newborns

Serum concentrations and half-life times of digoxin were determined in ten mature and nine premature newborns. Median serum digoxin concentration was 2.3 ng/ml (1.2 to 3.5 ng/ml) in mature newborns and 2.4 ng/ml (1.5 to 4.5 ng/ml) in premature newborns. Median serum digoxin half-life was 35 hours (17 to 52 hours) in mature newborns and 57 hours (38 to 88 hours) in premature newborns. The difference in serum digoxin half-life between the two groups is statistically significant. The relatively long serum digoxin half-life in premature newborns is probably due to immature renal function in this group. The data emphasize the need for cautious digoxin administration, especially in premature infants.

[Exercise-induced tachyarrhythmic syncopes with sinus bradycardia and normal QT-interval at rest (author's transl)]

Two children with exercise-induced syncopes are described. There was no evidence for congenital or acquired cardiac defects, cardiomyopathy or myocarditis in either of them. Both had sinus bradycardia and a consistently normal QT-interval at rest. In both, exercise induced regularly a multiform ventricular tachycardia, additionally in one on occasion a bidirectional, in the other a supraventricular tachycardia. Beta receptor blocking agents prevented tachyarrhythmias in both. Under treatment with beta receptor blocking agents, one child remained without syncopes, the other died suddenly. These cases underline the possiblility that exercise-induced syncopes may be caused by tachyarrhythmias even if the QT-interval of the resting Ecg is normal. In suspicious cases an exercise-Ecg is indicated.

[Congenital cerebral arterio-venous fistula with congestive heart failure in the newborn (author's transl)]

Two newborns with cogestive heart failure due to a congenital arterio-venous fistula involving the great vein of Galen are described. The main diagnostic criteria of this anomaly are a hyperactive heart, bounding carotid artery pulses, and a continuous murmur over the skull. The anomaly was visualized by cerebral angiography. In view of the frequent complications such as the development of hydrocephalus, operative treatment seems indicated.

[Congenital defects of the left-sided pericardium]

Three patients with congenital absence of the left pericardium and one patient with a partial left pericardial defect are described. Congenital absence of the left pericardium is characterized roentgenologically by levoposition of the heart, a prominent pulmonary artery segment and cardiac apex, interposition of lung between the left hemidiaphragm and the base of the heart, and unusual mobility of the heart. The electrocardiogram frequently shows right axis deviation, an incomplete right bundle branch block and leftward displacement of the transition zone in the precordial leeds. The anomaly has often been mistaken for other heart disease. As an isolated anomaly it is benign and does not require any treatment. Patients with a partial defect of the left pericardium can only be diagnosed lcinically if the left atrial appendage herniates through the defect. The herniation produces a protruding shadow along the left heart border and can be demonstrated angiographically and by fluoroscopy. In isolated cases death caused by herniation and strangulation of larger parts of the heart through a partial left pericardial defect has been described.

Serum digoxin concentration and half-life in newborn

Serum digoxin concentration and half-life were radioimmunologically determined in 9 mature newborns after 7 days medication with digoxin. The newborns were in respiratory distress treated with continuous positive airway pressure or were suspected to have serious congenital heart disease. Loading dose was 26 mug/kg body weight intravenously and 35 mug/kg body weight orally, respectively. Maintenance dose corresponded to 1/8th of the digitalization dose twice daily. The serum digoxin level 12 h after the last dose varied between 1.4 and 2.5 ng/ml (mean 2.0 ng/ml, Sx=0.4). The serum half-life of digoxin varied between 21.7 and 42.4 h (mean 30.0 h, Sx=7.7). The mean serum half-life of digoxin of 30 h attained values found in adults without renal disease. This suggests that the serum digoxin levels of newborns which are usually higher if compared with those of adults result from higher digoxin doses per unit body weight and not from diminished digoxin elimination.

[The bundle of his electrogram in ebstein-s anomaly of the tricuspid valve]

His-bundle electrograms were recorded in four patients with Ebstein's anomaly of the tricuspid valve. In two of the patients His potentials could only be demonstrated in the atrialized portion of the right ventricle while in the other two patients they were recorded in the right ventricle proper. The demonstration of His-potentials only in the atrialized portion of the right ventricle suggests that the origin of the free portion of the septal tricuspid valve leaflet is significantly displaced downward into the right ventricular cavity. The prolonged atrioventricular conduction time in two patients is due to conduction delay proximal to the bundle of His.

[Compression of trachea and esophagus by abnormal course of the left pulmonary artery (author's transl)]

A three months old infant with abnormal origine and course of the left pulmonary artery is described. The course of the left pulmonary artery between oesophagus and trachea causes narrowing of the distal trachea leading to in- and expiratory stridor. A ventral indentation of the oesophagus, visible on the lateral plane of an oesophageal roentgenogram, is characteristic for the anomaly which can be proven by pulmonary angiography.

Electron microscopy study of length and partial denaturation of Rhizobium bacteriophage DNA

By electron microscopy and melting of the DNA of some bacteriophages from the soil bacterium Rhizobium lupini, it was found that molecular weights range between 27 and 50 Mdaltons and GC contents between 53 and 62%. All DNAs studied are linear; one has exposed single-stranded terminals. Partial heat denaturation of two phage DNA permitted mapping of AT-rich sites within unique nucleotide sequences. The maps are asymmetric with respect to the midpoints of the DNA.