Biomedical subjects
Publications and source records attributed to M L Johnson.
Fifteen patients had hepatic hemangiomas removed with liver resections that ranged in extent from local excision to right trisegmentectomy. There was no mortality and little morbidity. The propriety and feasibility of extirpative treatment of such liver tumors has been emphasized by this experience.
Treatment of acquired aplastic anemia with androgens has been occasionally associated with the development of hepatic tumors. We have studied a 13-year-old boy with idiopathic aplastic anemia in whom oxymetholone treatment was associated with a partial hematological remission. Thirty-four months later, however, the patient developed multiple hepatic tumors. When oxymetholone therapy was discontinued, the aplastic anemia relapsed. He then underwent bone marrow transplantation from his HLA-A, B, and D-compatible sibling. This was followed by hematological and immunological reconstitution. The hepatic tumors underwent progressive regression after bone marrow transplantation. The patient is now 3 years post-bone marrow transplantation and is in complete remission of his aplastic anemia with no evidence of detectable liver tumors.
Ultrasound detected cystic intracranial lesions in 18 infants. Lesions included porencephaly (6 infants), hydranencephaly (1 infant), a quadrigeminal cyst (1 infant), Dandy-Walker syndrome (1 infant), and cavum septi pellucidi and Vergae (9 infants). Cystic lesions of the infant brain can be delineated accurately with ultrasound and distinguished from normal ventricular structures.
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Ultrasound examination of the infant brain has been performed in selected medical centers for many years. However, the equipment necessary for obtaining satisfactory visualization of the brain has only recently become commercially available. Currently, ultrasonography is an excellent, noninvasive, inexpensive, rapid, and safe imaging modality for the evaluation of hydrocephalus and other pathologic conditions of the neonatal brain. Ventricular size can often be evaluated in infants up to two or three years of age, but a detailed image of the brain parenchyma becomes more difficult to obtain in a term infant after the first two to three months of life. With the use of the water path and high resolution, real-time systems and with the delineation of structures by multiple projections, (axial, coronal, sagittal and occipital), complex abnormalities may be delineated.
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The rates of oxidation of several goitrogens by lactoperoxidase and the rates of inactivation of lactoperoxidase by the same goitrogens have been measured. The influence of iodide on both reactions has also been evaluated. It has been shown by us that iodide acts catalytically in regulating lactoperoxidase activity at pH 8.8. The rate data have been analyzed by a computer program which solves the differential equations for the above mentioned reactions. From this computer analysis we have been able to obtain binding constants of the goitrogens and inactivation rate constants of lactoperoxidase. Iodide was shown to inhibit goitrogenic activity either by increasing the rate of drug oxidation or by reducing the rate of enzyme inactivation, or both, depending on the particular drug. Iodide had little or no effect on the goitrogen-binding constants. We have also shown that the relative rates of enzyme inactivation can be correlated with the potency of the goitrogen as an antithyroid drug.
The effects of the antithyroid goitrogens, methylthiouracil and methylmercaptoimidazole, on the oxidation of N-acetyltyrosylamide at pH 8.8 by lactoperoxidase have been evaluated in the presence and the absence of iodide for the purpose of elucidating the effects of iodide. At pH 8.8, iodine is not oxidized. In the absence of iodide, the two antithyroid drugs inactivate lactoperoxidase by a second order process. When iodide is added before methylthiouracil or methylmercaptoimidazole, enzyme inactivation does not occur as rapidly and both goitrogens are readily oxidized. The kinetics of the oxidation reactions have been analyzed in order to obtain the equilibrium constant of the iodide . lactoperoxidase complex. Essentially the same iodide dissociation constant, i.e. 2 x 10(-5) M, was found by studying its effects on the kinetics of oxidation of the two antithyroid drugs. A large difference absorption spectrum is observed in the Soret region between native lactoperoxidase and lactoperoxidase inactivated by methylthiouracil.
The micellar properties of mixed, bovine gangliosides and purified galactosyl-N-acetylacetylgalactosaminyl (N-acetylneuraminyl) galactosylglucosylceramide were studied by gel filtration, equilibrium dialysis, and band and boundary centrifugation in sucrose gradients. The dissociation of micelles is very slow (days) in water and required us to approach equilibrium by association of monomers rather than by the dissociation of micelles. The gangliosides were therefore first converted into very low molecular weight aggregates (1-3 molecules) by dissolving them in Me2SO. Galactosyl-N-acetylgalactosaminyl(N-acetylneuraminyl)galactosylglucosylceramide was then diluted into aqueous sucrose gradients and sedimented by the boundary centrifugation technique. This gave a sedimenting micelle and a nonsedimenting monomer concentration of (1-2) x 10-10 M (or less) which corresponds to the critical micelle concentration value. The mixed gangliosides revealed two micellar sizes (i.e., 10 and 4.5 S), the slower sedimenting species being formed from the larger one with time (days). The critical micelle concentration of the mixed gangliosides was found to be approximately 10-8 M by a gel filtration, equilibrium dialysis, and band centrifugation.
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Commercially available high resolution, contact, gray scale imaging systems can now dependably visualize the normal and abnormal ventricular system as well as some other intracranial structures in all newborns. On 25 normal infants and 41 high risk infants, 135 B-mode echoencephalograms were performed. The technique for obtaining these scans is described. The normal lateral ventricle at the midbody in term infants is 0.9--1.3 cm wide (mean, 1.1 cm). Normal ratio of lateral ventricle to hemisphere is 28% (range, 24%--30%). High risk premature infants have a ratio of 31% (range, 24%--34%). The demonstration of hydrocephalus and cystic intracranial masses is reliable and the correlation with computed tomography is excellent. Postoperative or high risk infants can be repeatedly evaluated without radiation, at a lower cost, and more rapidly with ultrasound than with computed tomography. Ventricular size can be closely monitored and shunt failure detected at any early stage.
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The demonstration of fetal diseases and anomalies in utero can now be performed with a high degree of accuracy with modern ultrasonic equipment. This paper describes the more common and important fetal anomalies which can be demonstrated by ultrasound and indicates the importance of meticulous attention to technique and the significance of the acquistion of skill in real-time sonography by the physician-sonologist. The thoroughness of all obstetric sonographic examinations is emphasized to enable detection of unsuspected fetal anomalies. Specific methods to demonstrate these anomalies in the high-risk patient are also described. Several pitfalls in the diagnosis of fetal disease in utero are included which show the nonspecificity of some of the ultrasonic signs.
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