Biomedical subjects
Publications and source records attributed to E Chung.
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Insoluble collagen was prepared from bovine periodontal ligament. Isolation and characterization of CNBr peptides originating from the alpha1(I), alpha2, and alpha1(III) chains showed that the tissue contained both type I and type III collagens. Further evidence for the presence of type III collagen was obtained by the isolation of alpha1(III) chains from pepsin-treated ligament collagen, with properties similar to those of human alpha1(III) chains. Estimates based on the amounts of certain CNBr peptides indicated that about one-fifth of the collagen of periodontal ligament is type III, the remainder being type I collagen.
Long-spacing-segment crystallites prepared from type III collagen with the chain composition [alpha1(III)]3 and type I collagen with the chain composition [alpha(I)]i12alpha2 have been compared in the electron microscope after positive. staining with phosphotungstic acid and uranyl acetate. The comparison revealed several differences in intensities of the cross-striation bands as well as significant differences in band positions. The latter occur most prominently in three distinct regions of the crystallites. Further, crystallites prepared from type III collagen contain an additional intensely staining band in an area corresponding to the carboxy-terminal end of the molecule. The latter band is still observed following limited pepsin digestion and presumably represents a slight elongation of the helical portion of the type III molecule when compared to the type I molecule. In spite of the somewhat altered distribution of charged groups as indicated in studies on the long-spacing-segment crystallites, type III molecules are capable of forming fibrils of the native type with a cross-striation pattern and periodicity virtually identical to that observed when type I molecules are precipitated as native fibers.
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Collagen moleculess with the chain comizposition [alpha1(III)](3), have been isolated from pepsin-solubilized collagen of dermis, aorta, and leiomlyoma of the uterus by differential salt precipitation. On denaturation, approximately 90 percent of this collagen is recovered as a gamma component (300,000 daltons). Reduction and alkylation of the high-molecular-weight component yields alpha1(III) chains (95,000 daltons). In addition to containing cysteine, alpha1(III) chains exhibit several other compositional differences when compared to alpha1(I), alpha1(II), or alpha2 chains from human tissues.
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Ginsenoside-Rg1 (G-Rg1) from the roots of Panax ginseng C. A. Meyer has been shown to bind to the glucocorticoid receptor (GR). To further explore the effect of G-Rg1 binding to GR, a luciferase reporter gene containing two copies of a glucocorticoid response element was constructed and transiently transfected into FTO2B rat hepatoma cells. A dose-dependent induction of the reporter gene was observed in response to G-Rg1, and the inductive effect was blocked by treatment with the antiglucocorticoid RU486. In addition, both G-Rg1- and dexamethasone (Dex)-induced transcription was synergistically enhanced by the treatment of dibutyryl cAMP (Bt2-cAMP). G-Rg1 treatment also led to the down-regulation of intracellular GR content, which was similar to the effect of Dex. By showing that G-Rg1 down-regulates GR and induces GR-mediated transcription synergistically with cAMP, we conclude that G-Rg1 is a functional GR ligand in FTO2B cells.
The diminishing enthusiasm towards performing splenectomy (SPL) either as an integral part of surgical cancer management (SCM), or for staging/management (ST) of lymphoma, warranted our assessment of the extent of this trend in a minority population. We retrospectively analysed all SPL submitted to Surgical Pathology for histological processing over a 24-year period (1/1/70-12/31/93) at the Howard University Hospital, a predominantly African-American institution. Of the 446 SPL performed during the period, sixty-nine (15.5%) were performed as part of SCM/ST. Seventy-five per cent (52/69) were for solid intra-abdominal cancers (SIC) and 25% (17/69) for lymphoma. As a group, the patients were older, 71% over 40 years old) and showed a male predominance (61% males). Sixty-two per cent (43/69) of the SPL were performed in the decade 1970-1979. In the following decade 1980-1989, the frequency with which SPL was performed, had dropped to 33% (23/69). Four years into the current decade, 1990-1993, only 5% (3/69) of the SPL were performed for SCM/ST. These findings suggest that in African-Americans, the performance of SPL in ST/SCM has been declining over the years, which is in agreement with the current growing trends in cancer treatment i.e. to avoid unnecessary operations, limit morbidity, preserve important organs, maintain immunocompetence of the patient and to utilize advanced imaging techniques in ST/SCM.