Strain differences in distribution of phenylethanolamine N-methyltransferase activity from rat brain and adrenal gland.

Phenylethanolamine N-methyltransferase (PNMT) activity was measured in adrenal glands and medulla oblongata from 4 inbred rat strains, Fischer 344, Buffalo, Lewis and Sprague-Dawley rats. Adrenal enzyme activity was markedly different among the strains with the highest in Fischer, followed by Sprague-Dawley, Lewis and Buffalo rats in decreasing order. In medulla oblongata, the PNMT activity of Buffalo rat was the lowest being about one half of that of the other strains.

Different charge forms of aromatic-L-amino-acid decarboxylase.

The isoelectric points (pI) of aromatic-L-amino-acid decarboxylase (AADC) from two species, rat and cow, were determined by chromatofocusing. The enzyme from both rat brain and adrenal has a pI of 5.5, while the bovine adrenal enzyme has a different pI of 5.

DNA cytosine methylation and heat-induced deamination.

The heat-induced conversion of 5-methylcytosine (m5C) residues to thymine residues and of cytosine to uracil residues in single-stranded DNA was studied. The calculated rates for deamination at 37 degrees C and pH 7.4 were approximately 9.

A human DNA-binding protein is methylation-specific and sequence-specific.

A nuclear protein isolated from human placenta, methylated DNA-binding protein (MDBP), binds selectively to DNA enriched in 5-methylcytosine. We now demonstrate that MDBP is a sequence-specific, as well as methylation-specific, DNA-binding protein. From ten restriction fragments of pBR322 DNA methylated with human DNA methyltransferase, one was bound to MDBP very much more strongly than any of the others.

Hypoplastic left heart syndrome: report of a unique survivor.

A remarkable patient is described, a child who has survived until the age of 7 years with hypoplastic left heart syndrome (mitral and aortic atresia) without surgical intervention. The child has led an active, normal life and, aside from minimal cyanosis, has remained asymptomatic. The unique clinical course for this patient is the result of a number of favorable hemodynamic factors that have not been previously reported in an individual patient with hypoplastic left heart syndrome and intact ventricular septum widely patent ductus arteriosus, adequate retrograde coronary flow, unrestricted pulmonary venous return, and absence of significant vascular obstructive disease.

Low-dose transaxial tomography. An alternative to computed tomography for the evaluation of anteversion of the femur during childhood.

Low-dose transaxial tomography is a technique that can produce cross-sectional images of the hips and femurs in children to permit calculation of the angle of femoral anteversion. Transaxial tomography was compared with computed tomography in terms of measured radiation dose and image quality. Transaxial tomography was found to require at least 90% less radiation dose, and the images were judged to be acceptable for the determination of anteversion.

The accessibility of 5-methylcytosine to specific antibodies in double-stranded DNA of Xanthomonas phage XP12.

Antibodies specifically directed to 5-methylcytidine were raised in rabbits and purified by affinity chromatography. The accessibility of 5-methyldeoxycytidine (m5dCyd) to such antibodies was studied with DNAs from various origins. The reaction was followed by measuring the retention of radiolabelled DNA by antibodies on nitrocellulose filters, by immunoprecipitation, by gel filtration and was visualized with the electron microscope.

Human DNA sequences exhibiting gamete-specific hypomethylation.

Three human DNA sequences have been cloned from DNA regions which are strikingly undermethylated in sperm, highly methylated in adult somatic tissues, and methylated to an intermediate extent in tissues of extraembryonic origin. It is proposed that some such DNA sequences may function specifically early in embryogenesis or during gametogenesis. They may be subsequently extensively methylated in the embryonic cell lineage and methylated to a lesser extent in extraembryonic tissues in order to allow embryogenesis to proceed.

Pattern of undermethylation of the major satellite DNA of mouse sperm.

Enzymatic hydrolysis and base analysis by high performance liquid chromatography showed that mouse satellite DNA had 30-50% less 5-methylcytosine in sperm than in somatic tissue (1.59 mols % vs 2.40-3.

DNA methylation is not increased in mouse-human somatic cell hybrids.

The level of DNA methylation in three mouse-human cell lines that retained different human chromosomes and in the parental mouse and human lines has been determined by high-pressure liquid chromatography (HPLC). The level of methylation is similar in the hybrid and parental cells, indicating that interspecific somatic cell hybridization followed by preferential chromosome segregation can occur without an increase in overall DNA methylation.

DNA methylation in thermophilic bacteria: N4-methylcytosine, 5-methylcytosine, and N6-methyladenine.

While determining the minor and major base composition of the DNA from 17 types of thermophilic bacteria by high performance liquid chromatography (HPLC) of enzymatic digests, we have discovered a novel base, N4-methylcytosine (m4C). Its structure was proven by comparison of the DNA-derived nucleoside to the analogous authentic compound by HPLC, UV spectroscopy, and mass spectroscopy. Eight of the bacterial DNAs contained m4C.

Degradative enzyme systems in osteoarthritic cartilage.

In osteoarthritis, despite increased matrix synthesis, there is a reduction of both major matrix components, proteoglycan and collagen. This study suggests that this is the result of enhanced degradative activity intrinsic to the cartilage. Because osteoarthritis is a focal disease, histologic controls were used to measure the severity in different areas of the cartilage and in different specimens.

Comparative study of neutral proteoglycanase activity by growth plate zone.

The degradation of proteoglycans has been considered an essential step in the process of endochondral ossification. Neutral proteases, described in the growth plate, have been implicated in this process. If these neutral proteases are important in the endochondral process, their level of activity should be highest at the point where calcification is occurring.

Quantitative reversed-phase high-performance liquid chromatography of major and modified nucleosides in DNA.

Improved, highly accurate high-performance liquid chromatographic methods for the measurement of the major and modified nucleosides in enzymatic digests of DNA using a single column are described. Four high resolution separation protocols (isocratic, binary, ternary and high speed) with specifically improved selectivity for 5-methyldeoxycytidine (m5dCyd) from Ade, dIno and Guo are presented. From a detailed study of the various factors contributing to the precision and accuracy of the measurement, optimized conditions and quantitative protocols were established.

Analyzing forearm fractures in children. The more subtle signs of impending problems.

Poor results with pediatric forearm fractures, while infrequent, do occur. Systematic analysis is required to identify this relatively rare, evolving problem. The purpose of this retrospective study was to identify and organize factors that would help in this process.

Mouse mammary tumor virus DNA methylation: tissue-specific variation.

Mouse mammary tumor virus-specific DNA sequences endogenous to the BALB/c mouse are shown to exhibit variable levels of methylation in a tissue-specific manner. In DNA from both lactating mammary gland and spleen, MMTV-specific sequences were hypomethylated at specific HpaII and HhaI sites. These variably methylated sites were found in the terminal repetitive sequences of the endogenous viral genomes.

Digital intravenous cerebral angiography in neonates.

Digital intravenous cerebral angiography was performed in 13 neonates. Injections were made either centrally into the right atrium or peripherally into a distal vein. Seven infants suffered from anoxia, one infant had clinical brain death, another had focal infarcts, and two had intracranial hemorrhage.

Human placental DNA methyltransferase: DNA substrate and DNA binding specificity.

We have partially purified a DNA methyltransferase from human placenta using a novel substrate for a highly sensitive assay of methylation of hemimethylated DNA. This substrate was prepared by extensive nick translation of bacteriophage XP12 DNA, which normally has virtually all of its cytosine residues replaced by 5-methylcytosine (m5C). Micrococcus luteus DNA was just as good a substrate if it was first similarly nick translated with m5dCTP instead of dCTP in the polymerization mixture.

Instability of the distal tibiofibular syndesmosis after bimalleolar and trimalleolar ankle fractures.

We studied the late results after bimalleolar and trimalleolar ankle fractures in thirty-four patients after an average follow-up of four years. Twenty-one patients had had open reduction and internal fixation of the medial malleolus only and thirteen, internal fixation of both the medial malleolus and the lateral malleolus. Twenty-four lesions were supination-external rotation fractures; six, pronation-external rotation; and four, supination-adduction fractures.

A protein from human placental nuclei binds preferentially to 5-methylcytosine-rich DNA.

The methylation of vertebrate DNA at the 5-position of approximately 3-10% of its cytosine residues occurs in a sequence-specific and tissue-specific manner and has been implicated in the control of transcription. How these differences are established and how they mediate the initiation or maintenance of transcription are unknown. DNA methylation might also have other roles, such as modulating DNA replication, transposition, DNA repair or chromosome configuration.

DNA methylation inhibits the transfecting activity of replicative- form phi X174 DNA.

Replacement of virtually all the cytosine residues with 5-methylcytosine residues in the complementary strand of the replicative form (RF) of phi X174 DNA caused a 300- to 500-fold loss in its transfecting activity. Similar results were obtained with analogously methylated M13 RF. Transfection experiments with phi X RF hemimethylated in only part of the molecule, as assessed by analysis with restriction endonucleases, indicated that gene A of phi X, which needs to be nicked at a specific site by the gene A protein for RF replication, was not the main target for this inhibition by DNA methylation.

Partial purification and characterization of a proteoglycan-degrading neutral protease from bovine epiphyseal cartilage.

Degradation of the proteoglycan matrix is considered an essential step in the process of calcification in the growth plate. This laboratory has just described the presence of a protease in human growth plate cartilage that degrades proteoglycan at neutral pH. We report here the isolation, partial purification, and characterization of these proteoglycan-degrading neutral proteases of bovine epiphyseal cartilage.