Biomedical subjects
Publications and source records attributed to D Lang.
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Forty children with presumed ventricular tachyarrhythmic syncopes in the absence of structural heart disease were studied. Twenty-nine patients, one of whom was deaf, had a prolonged QT-interval in the resting electrocardiogram (Group 1); eleven patients had a normal QT-interval (Group 2). The median QTc-interval vas 0.51 s in Group 1 and 0.40 s in Group 2. Familial occurrence suggesting autosomal dominant inheritance was found in 21 of 28 normally hearing patients in Group 1 and in 2 of 11 patients in Group 2. Syncopes were definitely stress-induced in 22 patients in Group 1 and in all 11 patients in Group 2. Of 23 patients in Group 1 in whom an electrocardiogram was obtained during physical exercise, only one showed severe ventricular dysrhythmia. In contrast, all eleven patients in Group 2 developed severe ventricular dysrhythmia with exercise. Treatment with beta-blocking medication prevented further syncopes in 15 of 19 patients with several previous attacks in Group 1 and in 3 of 5 patients of Group 2. Four of the 29 patients in Group 1 died suddenly and one more remained apallic after an attack. Of the 11 patients in Group 2, four died suddenly and one retains severe cerebral damage after resuscitation from ventricular fibrillation. We conclude that, besides the group of patients with the long QT-syndrome, there may be a distinct group of patients with a consistently normal QT-interval and severe ventricular dysrhythmia with exercise. Patients of both groups are threatened by sudden death and are improved by treatment with beta-blocking medication.
The stage 0 sporulation locus spo0B has been mapped by transformation between the pheA and spoIVF loci. Analysis of the behavior of alleles of the spo0B locus in trpE26 merodiploid strains indicates that all of the known alleles of this locus comprise a single complementation group. The spoIVF88 mutation was found to reside in a separate complementation group. The chromosomal region surrounding and including the spo0B locus was cloned in the lambda vector Charon 4A. Extensive restriction endonuclease analyses of the inserts in these phage revealed that an EcoRI fragment of DNA of 2.3 kilobases had transforming activity for spo0B mutations. Examination of the physical and genetic maps of the locus suggested that the entire spo0B locus is contained within this fragment. Subcloning of restriction endonuclease fragments of the lambda inserts and transformation analyses allowed assignment of surrounding genetic loci to specific DNA fragments.
The aortico-left ventricular tunnel (AOLVT) is a rare abnormal communication between the ascending aorta and the left ventricle. The pathogenetic mechanism of this congenital anomaly is not completely understood. In addition to our 3 observations, 28 cases have been reported to date. In most cases the first symptoms appeared in early infancy. Clinical presentation and hemodynamics are identical to those of an aortic valve insufficiency. The correct diagnosis can be established by echocardiographic and angiocardiographic methods. Since the aortico-left ventricular tunnel is associated with congestive heart failure in infancy, in most cases surgical intervention is indicated in early childhood. The method of choice for surgical correction is a patch closure of the aortic orifice of the tunnel.
We report on 8 children with a right aortic arch and a retrooesophageal component of the upper descending aorta. The chest roentgenogram shows a right aortic arch and the oesophagogram a broad posterior indentation of the oesophagus in every case. Aortography was performed in 5 cases: in 2 children, the branches of the right aortic arch originate in a mirror image relationship to normal, in the other 3 children, the left subclavian artery originates as 4th branch from a retrooesophageal diverticulum of the upper descending aorta. Three children have an acyanotic congenital cardiac defect. Four of the children are asymptomatic while 3 have exertional dyspnoe and one suffers from dysphagia and frequent bronchitis. The symptoms are caused by compression of the oesophagus and the trachea by the right aortic arch, the retrooesophageal diverticulum and the patent or atretic ductus arteriosus originating from the latter. Only one child had to be operated for severe symptoms. There is a significant difference between the right aortic arch with or without a retrooesophageal component. The former mostly occurs alone and sometimes causes clinically significant oesophago-tracheal compression, while the latter is almost always combined with a cyanotic cardiac defect (tetralogy of Fallot, truncus arteriosus) but practically never causes a compression.
Between 1971 and 1978 the diagnosis of isolated ventricular septal defect was made in 149 patients. Most of these defects were small. In the majority of cases the diagnosis was made clinically. Spontaneous closure was assumed when, all other cardiac findings being normal, the heart murmur had disappeared. This took place in 50 of the 149 cases (34%) during the period of observation. Closure rate was independent of sex and birth rate, but related to size of defect and age of patient at time of diagnosis. Closure rate was 53% for small defects, 15% for larger ones. Because of the limited period of observation the reported spontaneous closure rate is less than the true one, estimated at 70-75% up to the age of nine years.
A 12-year-old boy with aplastic anemia developed severe but reversible cardiac failure after treatment with 200 mg/kg cyclophosphamide (4 x 50 mg/kg on four consecutive days) given as preparation for bone marrow grafting. This and previously reported cases demonstrate the possibility of cardiotoxicity after high doses of the drug.
We present an autopsy report of endocardial fibroelastosis of the right heart in two brothers of triplets. Beside this anomaly no other macroscopical malformations in the hearts were found. Morphologically an unusual hypertrophy of the subendocardial myocardiocytes in the right heart was observed. A history of tocolysis (sympathomimetic drugs for treatment of premature labour) was the main reason for publishing this case report. We could not answer the question if the drug was causative or only coincident with the observed lesions.
Antibodies to double-stranded DNA are found almost exclusively in serum of patients with the autoimmune disease systemic lupus erythematosus (SLE). Very little is known about the nature of the antibody binding site(s) on DNA. We report here the affinity purification from SLE serum of a group of IgG and IgM antibodies that bind in nitrocellulose filter binding assays to entirely double-stranded radiolabeled DNA devoid of single-stranded regions. We have studied the specificities of these purified antibodies by competition with various unlabeled polynucleotides and have visualized their binding to double-stranded DNA by electron microscopy. From the competition studies we could identify a type of purified antibody that binds only to entirely double-stranded DNA and other types that bind to both double- and single-stranded DNA. We report also that purified antibodies that bind to double-stranded poly d(AT) bind well to single-stranded DNA. They appear to be different from those purified antibodies that bind to native double-stranded DNA; antibodies to poly d(AT) can be shown to bind independently of antibodies to native double-stranded DNA. Our results suggest that a heterogeneous group of antibodies to double-stranded DNA can exist in a single SLE serum.
It is known that DNA in aqueous-ethanol solutions undergoes a B to A conformational change between 60% and 80% (w/w) ethanol. We have found that precipitates formed by adding salt to DNA in 60% and 80% ethanolic solutions can be very different. DNA precipitated from 60% ethanol forms a fine condensate that only slowly settles out of suspension and shows a characteristic differential scattering of circularly polarized light at long wavelengths. DNA precipitated from 80% ethanol forms a flocculent aggregate that exhibits the CD spectral features of the A conformation. Data from circular dichroism spectra of natural and synthetic nucleic acids and from X-ray diffraction patterns of the precipitates show that DNA molecules precipitated from 60% and 80% ethanol are, respectively, in the B and A conformation. Therefore, the different secondary conformations of DNA in ethanolic solutions are maintained during precipitation under these conditions. These results are of general importance for the preparation and study of condensed forms of DNA, since a relatively small change in the extent of dehydration can change the secondary conformation of DNA and markedly affect the character of a subsequent precipitate.
Deletion mutants of bacteriophage BF23 were isolated and the positions of the deletions were determined. Two different deletable regions were detected: one in the same region as previously reported for bacteriophage T5, which is closely related to BF23; and the other within both terminal repetitions. The former deletable region lay between positions 0.31 and 0.36, which represented the fractional lengths of the BF23 ( + ) DNA as measured from its left end. The latter deletion was evenly divided between the two terminal repetitions. The deletion in the left terminal repetition lay between positions 0.044 and 0.078 and was repeated in the corresponding region of the right terminal repetition between positions 0.966 and 1.0. The size of the DNA transferred to host cells during the first step of DNA transfer by BF23 carrying deletions in the terminal repetitions of its DNA was less than the size of DNA transferred during the first step by wild-type BF23 by an amount equal to the size of the deletion in each terminal repetition. This finding suggests the existence of a specific mechanism for delineating the position at which the first step of DNA transfer is stopped.
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Two groups each consisting of twelve healthy students received Fenoterol (0,03 microgram/kg/min) alone or in combination with Verapamil (1,2 micrograms/kg/min) intravenously. In both groups, heart rate, arterial blood pressure amplitude and echocardiographically determined left ventricular contractility parameters increased significantly and equally. These results suggest that Verapamil does not counteract the positive chronotropic and inotropic effect of Fenoterol.
In view of the known susceptibility of newborns to digoxin intoxication this study was undertaken in order to evaluate the effect of a relatively low digoxin dose on left ventricular contractility of newborn infants. Left ventricular ejection time, enddiastolic diameter and endsystolic diameter were measured by echocardiography before digitalization as well as between 2 and 4 h after the first digoxin dose (group 1 : 16 patients) or after full digitalization (group 2 : 12 patients). From these data, shortening fraction (SF) and mean velocity of fiber shortening (mean Vcf) were calculated. We found that SF and mean Vcf increased significantly in both groups after the first digoxin dose and after full digitalization. The increase was equal in newborns and infants. The mean plasma digoxin concentration after full digitalization was 2.2 ng/ml (range 0.7--4.4 ng/ml). These results demonstrate clearly the positive inotropic effect of a relatively low digoxin dose in newborns.
Postmortem tissue and plasma concentrations of digoxin were studied in 13 premature newborns, 6 mature newborns, and 5 older infants (age 1 to 14 months). The pertinent results of our study are as follows: The tissue digoxin concentrations tend to be higher in premature and mature newborns than in infants. This difference is statisitcally significant with respect to the concentration in myocardium and skeletal muscle. The renal digoxin concentration of premature newborns is significantly lower than that of mature newborns, the tissue concentrations in the other organs examined being essentially equal. In all age groups examined, skeletal muscle contains the greatest portion of digoxin, followed by the liver. The relation of myocardial to plasma digoxin concentration shows no significant difference between the various age groups. Within the groups, the variation is relatively large.
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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.
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