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Biomedical subjects

C S Chang

Publications and source records attributed to C S Chang.

At least 199 records · Page 11Linked to original sources
PubMed1985

delta-Aminolevulinate dehydratase in human erythroleukemia cells: an immunologically distinct enzyme.

Physicochemical and immunologic properties of delta-aminolevulinate (ALA) dehydratase in human K562 erythroleukemia cells were examined. ALA dehydratase activity was found to increase in K562 cells after treatment with butyric acid or selenium oxide. Enzyme activity in untreated K562 cells was comparable to that in normal adult erythrocytes but was increased three- to six-fold in K562 cells treated with 1.2 mmol/L butyric acid or 0.03 mmol/L selenium oxide. The Michaelis-Menten constant (Km), the inhibitor constant (Ki), and elution profile by diethylaminoethyl (DEAE) cellulose chromatography were similar for ALA dehydratase from K562 cells and normal human adult and human fetal erythrocytes. However, ALA dehydratase from K562 cells did not react with a monospecific rabbit antibody against ALA dehydratase purified from normal adult erythrocytes, although the antibody reacted with the enzyme from normal adult and fetal red cells. These findings indicate that ALA dehydratase in K562 cells is immunologically distinct from the normal enzyme.

Antibodies↗
PubMed1984

An immunological study of delta-aminolevulinic acid dehydratase specificity consistent with the phylogeny of species.

Rabbit antibody directed to homogeneously purified mouse liver delta-aminolevulinic acid dehydratase cross-reacted with the enzyme in erythrocytes, spleen, kidney and brain in the mouse. The antibody also cross-reacted with the enzyme in the rat, hamster and gerbil, but not in the rabbit, guinea pig, cattle, chick embryo, and human. In contrast, rabbit antibody against the human enzyme partially recognized the monkey enzyme, but not the enzyme in the other species. The species specificity of delta-aminolevulinic acid dehydratase in this study was consistent with the phylogenetic evolution of the species examined.

Animals↗
PubMed1984

Induction of delta-aminolevulinic acid dehydratase in mouse Friend virus-transformed erythroleukemia cells during erythroid differentiation.

The activity of delta-aminolevulinic acid (ALA) dehydratase, an enzyme involved in heme biosynthesis, has been shown to increase in Friend virus-transformed murine erythroleukemia (MEL) cells during erythroid differentiation. In this study, the nature of the increase in ALA dehydratase activity in MEL cells was examined using a monospecific antibody directed to the enzyme. A sevenfold increase in ALA dehydratase activity was observed after cells had been treated with 1.5% Me2SO for 5 days. Ouchterlony double immunodiffusion analysis showed that lysates from untreated and Me2SO-treated MEL cells formed a single precipitin line with rabbit IgG directed to the normal mouse liver ALA dehydratase. A single arc of identity was also observed with the lysates from normal mouse erythrocytes, spleen, liver, and lysates from both uninduced and induced MEL cells. Rocket immunoelectrophoresis demonstrated that lysates from both uninduced and induced cells formed rockets with the IgG and that the peak height of the rocket was proportional to the ALA dehydratase activity applied. The slope of linear plots of rocket peak heights v ALA dehydratase activity was identical for lysates from uninduced and Me2SO-induced cells. Succinylacetone, a potent inhibitor of ALA dehydratase, was shown to markedly inhibit the activity of the enzyme, but did not interfere with the synthesis of ALA dehydratase induced by Me2SO treatment. Me2SO-induced increases in ALA dehydratase activity and the enzyme protein were both blocked by the simultaneous treatment of cells with 5-bromo-2'-deoxyuridine (BrdU). BrdU-mediated repression of ALA dehydratase was partially overcome by treating the cells with thymidine. These data demonstrate that increased ALA dehydratase activity in MEL cells undergoing erythroid differentiation after Me2SO treatment is due to de novo synthesis of the same enzyme protein present in uninduced MEL cells as well as in normal erythrocytes. This represents the first direct demonstration of an increase in a heme biosynthetic pathway enzyme protein in erythroid cells undergoing differentiation.

Animals↗
PubMed1983

Histologic study of hydroxylapatite as an implant material for mandibular augmentation.

Dogs were used to compare supraperiosteal implantation of hydroxylapatite with subperiosteal implantation with and without partial decortication of the underlying bone. Whereas supraperiosteal implants were unstable, nine months of observation indicated that the subperiosteal implants developed a strong attachment and mechanical stabilization as a result of formation of investing fibrous and osseous tissues. These results provide a basis for a technique of alveolar augmentation and denture construction.

Alveolar Ridge Augmentation↗
PubMed1983

Developmental outcome of infants with grade III intraventricular hemorrhage.

To determine the developmental outcome of premature infants weighing 1,750 gm or less at birth and who had grade III intraventricular hemorrhage (IVH), we followed up ten infants with IVH confirmed by computed tomography (CT) and ten CT-negative control infants until they were 12 months corrected age. The infants were evaluated at three-month intervals with neurologic examinations; hearing, speech, and language assessments; Bayley testing; and evoked response studies. Normal criteria were defined in each area. Eight of the ten grade III IVH survivors had identifiable defects, with a predominance of motor deficits, as assessed by two or more parameters. Only three of the ten patients without IVH had two or more suspicious or abnormal assessments. Infants with grade III IVH may have widespread damage. A multidisciplinary approach to evaluating these patients is mandatory to determine the full extent of various deficits. Similar studies of infants with all degrees of IVH may help to define its full impact on their long-term development.

Articulation Disorders↗
PubMed1983

Biochemical analysis and electron microscopy of human mitral valve collagen in patients with various etiologies of mitral valve diseases.

Biochemical analyses and electron microscopy of mitral valve collagen were carried out in 29 patients with various mitral valve diseases. They were divided into 3 groups: (1) rheumatic heart disease (15 patients), (2) isolated rupture of chordae tendineae (8 patients), and (3) floppy mitral valve (6 patients). Normal mitral valves obtained at necropsy from 6 patients who died from extracardiac causes were used for control observations. Results of the electrophoretic analysis of the collagen of normal and diseased valves showed that all valves contained collagen types I, III, and AB collagen with similar electrophoretic patterns. Electron microscopic observations and comparisons of the segment-long-spacing crystallites of each type of collagen revealed similar band patterns, irrespective of the normal or diseased valves sources. It is concluded that the composition and primary molecular structure of mitral valve collagen are usually not altered in a wide variety of disease processes affecting the mitral valve.

Adolescent↗
PubMed1983

Hyperthermia-induced intracellular ionic level changes in tumor cells.

The intracellular content of potassium (K) ions in P815 cells decreases when the media pH is lowered, and it increases when media pH is raised. The determination of the ion content therefore requires accurate control of the medium pH. The K ion content measured both by the flame emission method and by the K analog. 86Rb, exhibits a decline when the cells are incubated at 43 degrees C at a fixed pH chosen between 7.4 and 6.7. The chloride content also decreases while the sodium content does not change by a significant amount. Under the same hyperthermic conditions the intracellular pH decreases by a fraction of a pH unit. Simultaneously, the cell water volume increases by 20%, as measured by tritiated water. In the final analysis, hyperthermia produces an apparent deficit in the cellular osmolarity. A possible explanation is given.

Animals↗
PubMed1982

Effects of metalloporphyrins on hemoglobin formation in mouse Friend virus-transformed erythroleukemia cells. Stimulation of heme biosynthesis by cobalt protoporphyrin.

Mouse Friend virus-transformed erythroleukemia cells in culture undergo erythroid differentiation when treated with a variety of compounds including iron protoporphyrin IX, i.e. hemin. Exogenous hemin is not only incorporated into hemoglobin in these cells but also stimulates heme biosynthesis (Granick, J. L., and Sassa, S. (1978) J. Biol. Chem. 253, 5402-5406). In this study, we examined whether metalloporphyrins other than hemin can also induce differentiation, and if so, whether they can also be incorporated into hemoglobin. Among eight metalloporphyrins examined in culture of these cells, i.e. Co, Mn, Cu, Mg, Ni, Zn, Sn, and Cd protoporphyrin IX, only Co protoporphyrin (10(-4) M) was found to significantly increase the biosynthesis of heme and hemoglobin. In contrast to hemin-mediated induction of erythroid differentiation, Co protoporphyrin was not incorporated into hemoglobin in Friend cells. These data indicate that Co protoporphyrin induces the formation of heme and hemoglobin in Friend cells and that these increases are due to the enhancement of heme biosynthetic activity.

Animals↗
PubMed1978

Encephalocraniocutaneous lipomatosis.

Two patients with encephalocraniocutaneous lipomatosis have been studied. The main features of the syndrome are unilateral cutaneous and ophthalmologic lesions with ipsilateral cerebral malformations. Seizures beginning in infancy and varying degrees of mental retardation are present in affected patients. The involved tissues are derived from the embryonic ectodermal and mesodermal layers.

Brain Neoplasms↗
PubMed1976

Studies on the biosynthesis of acylphosphatidylglycerol in Escherichia coli B and B/r.

The present study has demonstrated that one molecule of acylphosphatidylglycerol was synthesized from two molecules of phosphatidylgycerol by the transacylation reaction in which phosphatidylglycerol acted both as an acyl donor and an acceptor. Phosphatidylethanolamine was identified as an another acyl donor, participating in acylphosphatidylglycerol formation. These results are discussed in terms of a new pathway for the turnover of phosphatidylglycerol in Escherichia coli.

Acyltransferases↗
PubMed1975

Heme biosynthesis in bacterium-protozoon symbioses: enzymic defects in host hemoflagellates and complemental role of their intracellular symbiotes.

Heme biosynthetic activity in the symbiotic association involving crithidial flagellates and intracellular bacteroids was studied by enzymic, nutritional, and isotope incorporation experiments. Component organisms and their complexes in this association were analyzed separately to determine the underlying cause of the hemin requirement of hemoflagellates and the role of symbiotes in sparing this requirement of two crithidial species. Nutritional study of symbiote-free flagellates showed that their growth requires at least 0.1 mug/ml of hemin, which can be substituted by protoporphyrin IX, but not by the porphyrin precursors, delta-amino-levulinic acid or porphobilinogen. These flagellates, in the presence of protoporphyrin IX, incorporated 59Fe into heme, indicating that they possess ferrochelatase (EC 4.99.1.1), the terminal enzyme in the heme biosynthetic pathway, which catalyzes the insertion of iron into protoporphyrin IX. In symbiote-containing flagellates serially cultured in a defined medium free of tetrapyrrole compounds, heme and porphyrins can be detected by a fluorophotometric method, indicative of heme biosynthesis. Study of [14C]glycine incorporation into heme showed that the rate is much higher in symbiote-containing flagellates than in those without symbiotes. Microassay of uroporphyrinogen I synthase [EC 4.3.1.8; porphobilinogen ammonia-lyase (polymerizing)] revealed that the specific activity is high in symbiote-containing flagellates and higher still in isolated symbiotes, but essentially negligible in symbiote-free organisms. It is concluded that the bacterial symbiotes augment a very limited heme biosynthetic capacity of host flagellates by supplying uroporphyrinogen I synthase and perhaps other enzymes preceding ferrochelatase in the heme biosynthetic chain.

Aminolevulinic Acid↗