Fetal hydrocephalus: diagnosis and management.
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Cerebrospinal Fluid Shunts↗
Biomedical subjects
M L Johnson
Publications and source records attributed to M L Johnson.
Fetal treatment 1982.
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Congenital Abnormalities↗
A simplified method for computer analysis of autoradiograms from two-dimensional gels.
A simple method is described for computer analysis of a discrete number of spots on autoradiograms from two-dimensional gels. The method involves digitizing the density data on an autoradiograph with a rotating drum densitometer and displaying the data on a graphics computer terminal. The software allows the operator to select the boundaries of the spots to be analyzed from the terminal, then integrates the the density of the spots and tabulates the data. Graphics options allow the operator to display a computer-generated image of the area of the film being analyzed. Accurate integration of weak or overlapping spots is accomplished by a nonlinear least squares fit of the density data to normal Gaussian curves in the x and y dimensions followed by analytical integration of the equations. Since the software is written in Fortran IV and the equipment required to run the programs is available in most computing centers, this technique should allow laboratories of modest resources to quantitate information from two-dimensional gels.
Animals↗
A surgical approach to the treatment of fetal hydrocephalus.
Untreated fetal hydrocephalus results in gross cranial and facial abnormalities and profound brain damage. In an attempt to prevent both, a ventriculoamniotic shunt was implanted in a fetus with probable X-linked aqueductal stenosis and hydrocephalus. Performed at 24 weeks' gestation, the procedure used techniques similar to those used for intrauterine transfusion. After shunt placement, the fetal head size grew normally until after the 32d week, when the shunt failed. A cesarean delivery was performed at 34 weeks' gestation. The infant received a standard ventriculoperitoneal shunt after delivery, and his neonatal course has been evaluated through the first three months of life. In selected cases, the ventriculoamniotic shunt may be an acceptable treatment for fetal hydrocephalus.
Adult↗
Insulin and dexamethasone effects on liver fructose bisphosphatase.
Insuling perfusion of isolated diabetic rabbit liver and glucocorticoid perfusion of isolated normal rabbit liver resulted in an increased accumulation of immunoreactive fructose bisphosphatase (nmol/g). The insulin effect was maximal at 30 min with concentration (nmol/g) and specific activity (units/nmol) returning to normal within 2 h after insulin removal. Similarly, dexamethasone perfusion increased enzyme concentration and decreased its specific activity; however, the effects were maximal at 60-120 min. The results parallel those previously demonstrated in whole animals and establish that both hormones influence the enzyme by direct effects on the liver.
Animals↗
Thermodynamic analysis of human hemoglobins in terms of the Perutz mechanism: extensions of the Szabo--Karplus model to include subunit assembly.
The stereochemical postulates of Perutz for the mechanism of hemoglobin [Perutz, M. F. (1970) Nature (London) 228, 726--739] have been formulated into a statistical thermodynamic model. The model is based on that of Szabo and Karplus [Szabo, A., & Karplus, M. (1972) J. Mol. Biol 72, 163--197] but has been extended to include the properties of dissociated dimers in equilibrium with tetramers. The dissociation eliminates the alpha 1 beta 2 intersubunit contact which is the major site of ligand-linked structure change. The model quantitatively describes the coupling between binding of oxygen and protons in dimers and tetramers, the change in quaternary structure, and the breaking of salt bridges which are assumed to stabilize the deoxy quaternary structure. The extended model has been tested against an extensive series of recent experimental data from our laboratory and elsewhere on the ligand-linked dimer-tetramer assembly in normal human hemoglobin A and in the variant hemoglobin Kansas (beta 102 Asp leads to Asn). Two versions of the model were used which differ in the properties of the dissociated dimers. For both hemoglobins, the models were found capable of simultaneously describing the data on the ligand-linked dimer-tetramer assembly and predicting the tetramer Bohr effect. However, neither model predicted reasonable values for the tetramer Bohr effect without simultaneously predicting unreasonable values for the affinities of individual chains. Both models incorrectly predict preferential binding of oxygen to the alpha or beta chains within the tetramer. These results argue against the Perutz mechanism for the molecular processes of hemoglobin.
Hemoglobin A↗
Insulin binding to the HL-60 human promyelocytic cell line.
The HL-60 cell is a human leukemic promyelocyte that can be grown in liquid suspension culture. This cell line binds radiolabeled insulin in a rapid, reversible specific manner indicating that it contains cells surface insulin-binding sites. these sites show a pH optimum of 7.8-8.0. Maximal binding was achieved in approx. 60 min at 22 degrees C and was linear with cell number between 5 X 10(6) and 10(8) cells per ml. Displacement of labeled insulin by unlabeled hormone was consistent with a 'two site' model with a high affinity site of 2.71 +/- 0.55 X 10(8) M-1 and 8700 sites per cell. Release of labeled insulin from its binding site was accelerated by unlabeled insulin at temperatures above 22 degrees C, but not at 4 or 15 degrees C. We conclude that the HL-60 cell contains cell surface binding sites for insulin with properties similar to other well-described insulin receptors of other tissues.
Cell Line↗
Affinity labeling of the plasma membrane 3,3',5-triiodo-L-thyronine receptor in GH3 cells.
The binding of 3,3',5-triiodo-L-thyronine (T3) to GH3 rat pituitary tumor cells was studied at 15 degrees C and was shown to be saturable, reversible, and stereospecific. Least-squares analysis of the binding data showed two classes of binding sites with dissociation constants of 1.8 +/- 0.2 nM and 260 +/- 30 nM and binding capacities of (5.2 +/- 0.2) X 10(4) and (1.6 +/- 0.2) X 10(6) sites per cell, respectively. Affinity labeling of intact cells was carried out by incubation of cells with 0.3 nM N-bromoacetyl-[125I]T3 at 15 degrees C for 1 hr. Analysis of the cellular extracts by sodium dodecyl sulfate gel electrophoresis showed three labeled protein bands with apparent molecular masses of 55, 47, and 33 kilodaltons (kDal) in a ratio of 86:7:7. The labeling of only the 55-kDal protein band was selectively reduced to 50% by 20 microM unlabeled T3. Highly purified plasma membranes of GH3 cells were prepared and shown to be free of nuclei. Affinity labeling of the purified plasma membranes gave the same labeling pattern as with intact cells. Peptide mapping by Staphylococcus aureus V8 digestion of the 55-kDal protein from cells or plasma membranes gave the identical peptide fragments. Thus the 55-kDal protein labeled from intact cells is the same protein as that from purified plasma membranes. These results together with our earlier findings [Horiuchi, R., Cheng, S.-y., Willingham, M. & Pastan, I. (1982) J. Biol. Chem. 257, 3139-3144] suggest that the 55-kDal protein may be involved in mediating the uptake of T3 in GH3 cells.
Affinity Labels↗
Clindamycin therapy of experimental Staphylococcus aureus endocarditis.
The efficacy of clindamycin in the treatment of experimental endocarditis in rabbits was compared with that of nafcillin. Both drugs were administered intramuscularly three times daily for 5 days, clindamycin at doses of 6.25, 12.5, 25, or 50 mg/kg and nafcillin at a dose of 200 mg/kg. The minimum inhibitory and bactericidal concentrations (0.125 microgram/ml) of clindamycin for the test strain of Staphylococcus aureus were very similar to the corresponding concentrations (0.25 microgram/ml) of nafcillin. The effectiveness of clindamycin against the experimental endocarditis was dose dependent. The therapeutic accomplishments of the two highest clindamycin doses were equivalent to those attained with 200 mg of nafcillin per kg. The rates of sterilization of vegetations were equal when the serum bactericidal titers of these drugs were greater than or equal to 1:8. In special situations the administration of clindamycin in high doses could prove useful in the treatment of S. aureus endocarditis.
Animals↗
Optimal resources for ultrasonic examination of the heart. Echocardiography study group.
This paper provides guidelines for the optimal, rather than minimal, performance of ultrasonic examination of the heart for current clinical applications using conventional echocardiographic equipment. Since the original report of this Inter-Society Commission on Heart Disease Resources Committee in 1975, M-mode echocardiography has continued to be a valuable clinical tool, and two-dimensional echocardiography has been developed. Guidelines are presented for optimal physician and cardiac sonographer training, case loads, space and support systems, equipment design features and performance testing, and administrative considerations. The developing area of Doppler ultrasound and the competitive technologies are noted.
Cardiology↗
Placement of ventriculo-amniotic shunt for hydrocephalus in a fetus.
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Amniotic Fluid↗
Dexamethasone effects on liver pyruvate kinase.
Dexamethasone in the medium perfusing isolated rabbit livers caused a fast-acting and reversible effect on liver pyruvate kinase. The effect was to lower the assayable V activity (units/g tissue) without changing the concentration (nmol/g enzyme protein). In effect, glucocorticoid lowered the specific activity (units/nmol of enzyme) by direct action on liver. The effect on liver pyruvate kinase is mediated by a relatively stable alteration; 30 min after perfusate (with steroid) was replaced by perfusate (without steroid), the effect remained strongly evident.
Animals↗
Molecular characterization of human clathrin.
Clathrin extracted from coated vesicles at pH 8.0 sediments as a single boundary with 8.1S sedimentation constant (s020,w) of 8.1 +/- 0.1 S. Sedimentation equilibrium gave a molecular weight (Mr) of 610 000 +/- 30 000. The clathrin frictional ratio (pH 7.5) computed from s020,w and Mr is very large, i.e., 3.06 +/- 0.18. Analysis of the circular dichroic spectrum in the far-ultraviolet showed that about half of the peptide residues are in a alpha-helical conformation. The molecular weight of a preparation of clathrin purified to homogeneity on a Sepharose CL-4B column in 6 M guanidine hydrochloride was 170 000 +/- 26 000 by sedimentation equilibrium, which is in agreement with the values we and others obtained by sodium dodecyl sulfate gel electrophoresis. The 8.1S clathrin species may be regarded as the "native" promoter since (1) it is extracted from coated vesicles by an extremely mild procedure, (2) it is stable over considerable ranges of pH, temperature, and ionic strength, and (3) it readily polymerizes into characteristic closed lattice structures resembling those observed in coated vesicles in the electron microscope. The 8.1S clathrin molecule self-associates at pH 6.3 to form two very high molecular weight species with average sedimentation coefficients of 150 and 300 S. The sedimenting boundaries of both of these species have been analyzed to reveal their molecular heterogeneity. The two species observed by sedimentation velocity may correspond to the two sizes of coated vesicles previously reported to be present in some cells when observed by electron microscopy. Analysis of the sedimentation pattern in the ultracentrifuge also gives the amount of unreacted 8.1S clathrin from which the yield of polymerizable clathrin is obtainable. This methodology can therefore be employed to estimate the quality of the 8.1S preparation of clathrin and thereby affords an assay of its activity.
Circular Dichroism↗
Linked functions in allosteric proteins. Extension of the concerted (MWC) model for ligand-linked subunit assembly and its application to human hemoglobins.
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Allosteric Site↗
Ultrasonic evaluation of a cervical mass in pregnancy.
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Adult↗
Detection of neonatal intracranial hemorrhage utilizing real-time and static ultrasound.
Accurate assessment of neonatal brain anatomy and pathology can now be obtained with commercially available ultrasound equipment. Intracranial hemorrhage (ICH) has a 50% to 60% incidence in premature infants under 32 wk gestational age and is felt to be one of the leading causes of neonatal morbidity and mortality. Computerized tomography (CT) has been the standard for detecting ICH; this study demonstrates that ultrasound is equally accurate and sensitive. Real-time examination through the anterior fontanelle resulted in 100% accuracy when compared with CT in a prospective study. Compound axial scans through the parietal bone were not as accurate, with a sensitivity of 91% and a specificity of 85%. If available, good quality real-time, transfontanelle sector ultrasound should be the screening procedure of choice for detecting and following intracranial hemorrhage in the high-risk premature infant.
Cerebral Hemorrhage↗