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Biomedical subjects

C M Chang

Publications and source records attributed to C M Chang.

At least 181 records · Page 10Linked to original sources
PubMed1975

The inhibition of macrophage migration inhibtory factor (38485).

Analogs of EACA were capable of inhibiting the in vitro activity of macrophage migration inhibitory factor (MIF). The most active analog of EACA in terms of MIF inhibition had four methyl groups separating an acetylated amino group from a free carboxyl group. This compound, acetylated 5-amino valeric acid, was capable of inhibiting completely MIF activity in vitro at a concentration of less than 10-6 M without demonstrating any appreciable antitryptic activity, even at 10-3 M. Antitryptically active EACA did not inhibit MIF except at very high concentrations (10-2M). Further, the most purified preparations of MIF obtained from aqueous extracts of thymus that we have studied contained no significant proteolytic activity upon denatured hemoglobin at pH 3-8. Therefore, we do not correlate anti-tryptic with anti-MIF activity in vitro.

Aminocaproates↗
PubMed1974

Comparison of the chemical structure and biological activities of the glycolipids of Salmonella minnesota R595 and Salmonella typhimurium SL1102.

It has been assumed in the past that the lipid moieties of endotoxic lipopolysaccharides are quite similar if not identical. This has been tested in the reported work here, where the chemical composition and biological activities of the glycolipids of two heptoseless Re mutants, Salmonella minnesota R595 and Salmonella typhimurium SL1102, have been studied and compared. The two glycolipids, extracted with chloroform-methanol (4:1), showed identical thin-layer chromatographic patterns. The molar ratios for hexosamine, fatty acids, phosphorus, 2-keto-3-deoxyoctonate, total amines, and total nitrogen of the purified glycolipids were in the same range, but small differences could be established. Both glycolipids contained the same major fatty acids, i.e., lauric, myristic, palmitic, and 3-hydroxymyristic acids, in similar but not identical ratios. On paper electrophoresis, the acid hydrolysates of the two glycolipids showed analogous components. In the determination of molecular weight, whereas S. minnesota R595 glycolipid did not show concentration dependence, the molecular weight measured for S. typhimurium SL1102 increased with its concentration. The molecular weight of the fully endotoxic R595 glycolipid has been found to be 17,000 +/- 1,500. Both glycolipids showed similar activities in the Shwartzman skin reaction, Limulus-lysate clotting assay, mouse lethality, and enhancement of nonspecific resistance, but the R595 preparation appeared to be more active on a weight basis in some parameters than SL1102. Using passive hemagglutination, we observed cross-reactivity between the glycolipids. In the gel-diffusion test, they revealed clear identity. The antiserum against S. minnesota R595 neutralized the Shwartzman skin reactivity not only of R595 but also of SL1102 glycolipid. These results confirm that there are identical immunodeterminant group(s) in the two glycolipids. On the other hand, chemical analytical data for two glycolipids showed only similarities, indicating that although both glycolipids are of comparable chemical nature, differences between them exist.

Antibodies, Bacterial↗
PubMedDate not supplied

Nuclear antigens reacted with sera and ascites of hepatocellular carcinoma patients.

In order to study hepatocellular carcinoma-associated antigens, screening of sera and ascites was done from hepatocellular carcinoma patients having antibodies reactive with three hepatocellular carcinoma cell lines (PLC/PRF/5, Hep 3B and HA22T/VGH). The indirect immunofluorescent antibody test was used. Ten of 86 (11.6%) sera and 3 of 14 (21.4%) ascites from hepatocellular carcinoma patients showed positive bindings, whereas only 1 of 35 (2.8%) sera, none of 4 (0%) ascites from chronic hepatitis patients and 3 of 60 (5%) normal human sera had positive immunofluorescent antibody activity. The binding specificities of these positive specimens were further defined by other human cancer cell lines and mouse NIH/3T3 fibroblasts. The antinuclear antibody test against mouse liver sections was also performed. The results suggested that antigens identified by the two tests may not be identical. The nature of nuclear antigens reactive with one of the serum samples, S83, and ascites A83 were characterized. These antigens were sensitive to trypsin but not to RNase A and DNase I. Further studies by radioimmunoprecipitation and two-dimensional gel electrophoresis with serum S83 and ascites A83 showed two acidic phosphorylated antigens with molecular weights of 77 and 79 kd, which had a pI around pH 5.2. The presence of a large amount of these two phosphorylated proteins in 5 of 7 human hepatocellular carcinoma cell lines suggests that these two antigens might play some roles in the carcinogenesis or progression of human hepatocellular carcinoma.

Animals↗
PubMedDate not supplied

Unusual case of Klüver-Bucy syndrome in a Chinese boy.

Following an encephalopathic illness, a 13-year-old Chinese boy had a partial form of Klüver-Bucy syndrome with emotional disturbance, recent memory loss, hypersexuality, and polyphagia. Other unusual features included narcolepsy, polydipsia, and polyuria. Virologic studies failed to incriminate the etiologic agent, including herpes simplex virus. Brain biopsy of the frontal lobe demonstrated Alzheimer type II astrocytosis.

Adolescent↗