Search PubMed⌕ Search

Biomedical subjects

J Chung

Publications and source records attributed to J Chung.

At least 199 records · Page 11Linked to original sources
PubMed1981

Effect of oxygenated sterol compounds on human bone marrow granulocytic progenitor cells.

Oxygenated sterol compounds are potent inhibitors of sterol and DNA synthesis in mammalian cells. We studied the effects of oxygenated sterols on human marrow granulocytic progenitor cells in vitro (CFU-C). 25-Hydroxycholesterol was found to be a potent inhibitor of sterol synthesis in marrow mononuclear cells, with 50% inhibition occurring at approximately 10(-7) M. This compound, as well as 6-ketocholestanol, 7-ketocholesterol, and 20 alpha-hydroxycholesterol, also demonstrated marked inhibition of CFU-C proliferation. The latter effect, which was not a result of direct cytoxicity of the compounds, was reversible by cholesterol, but not by mevalonic acid. We conclude that inhibition of sterol synthesis by oxygenated sterol compounds may be insufficient to explain their suppression of CFU-C proliferation.

Bone Marrow↗
PubMed1979

Inhibition of human lymphocyte E-rosette formation by oxygenated sterols.

25-Hydroxycholesterol, 20 alpha-hydroxycholesterol, 7 alpha-hydroxycholesterol, and 5 alpha-hydroxy-6-ketocholestanol, when added to cultures of human lymphocytes in lipoprotein-depleted medium (LPDM) at a concentration of 2.5 x 10(-6) M, inhibit E-rosette formation with sheep red blood cells. 20 alpha-Hydroxycholesterol, 7 alpha-hydroxycholesterol, and 5 alpha-hydroxy-6-ketocholestanol are more potent inhibitors than 25-hydroxycholesterol. The inhibitory effect of 5 alpha-hydroxy-6-ketocholestanol on E-rosette formation appears after 15 min of exposure; with the other three compounds, an exposure time of 18 hr is necessary. The inhibitory effect of E-rosette formation can be abolished by addition of free cholesterol, low-density lipoprotein, or high-density lipoprotein to the LPDM or by incubation of the cells in normal AB serum, but not by the addition of mevalonic acid to the LPDM. These observations suggest that the capacity of oxygenated sterol compounds (OSC) to inhibit E-rosette formation is independent of their inhibitory effect on sterol synthesis. It is possible that OSC inhibit E-rosette formation as a consequence of their insertion into the lymphocyte membrane as cholesterol analogues.

Cell Survival↗
PubMed1976

Apoproteins of human serum high density lipoproteins. Isolation and characterization of the peptides of Sephadex fraction V from normal subjects and patients with abeta-lipoproteinemia.

1. Sephadex fraction V, obtained from human serum high density lipoprotein apoprotein (HDL apoprotein) of normal subjects and of patients with abetalipoproteinemia, was resolved by DEAE-cellulose ion exchange column chromatography into several fractions which were defined in terms of amino acid composition, NH2- and COOH-terminsls, sialic acid content, immunologic and electrophoretic properties, and in vitro activation of purified lipoprotein lipase from rat adipose tissue. 2. Fraction V of HDL apoprotein of both normal and abetalipoproteinemic subjects was found to contain polypeptides corresponding to apolipoproteins C-I, C-II, C-III-1, and C-III-2, which had been described previously in very low-density lipoproteins (VLDL). The content of apo C-III-1 in abetalipoproteinemia-HDL was very low, whereas the percentage, by weight, of apo C-I was about twice as high as that in the normal subjects studied. Furthermore, both normal and abetalipoproteinemia-HDL apoprotein contained a previously unreported peptide which had a molecular weight of about 7 000 and electrophoretic, chemical, and immunological properties distinct from those of the known C apolipoproteins. Of all of the peptides comprising fraction V, only apo C-II activated a purified preparation of rat adipose tissue lipoprotein lipase. This was the case for both normal and abetalipoproteinemic subjects.

Amino Acids↗
PubMed1967

Dissociation of low density lipoprotein-antibody precipitates at alkaline pH.

The effect of alkaline pH on the dissociation of immunoprecipitates of low density lipoproteins (LDL) of the S(f) 0-10 class was studied by immunological and ultracentrifugal methods. The precipitates prepared at the equivalence point were dissolved and centrifuged in sodium chloride solutions of density 1.063 and pH's between 10.25 and 11.5. Analytical centrifugation of the top fraction, which floated at density 1.063, after dialysis against 0.9% sodium chloride of pH 7.4 revealed the presence of LDL and of soluble LDL-antibody complex. The amount of soluble complex was greater for the preparations obtained at lower pH than those obtained at higher pH and was undetectable at pH 11.5. The yield of immunoglobulin from the bottom fractions was maximal when the pH of the centrifugation medium was 11.0. Below pH 11.0, the greatly reduced yield of immunoglobulin was due partly to incomplete dissociation and partly to aggregation of soluble complex, while above pH 11.0 the decreased yield was possibly due to alkaline denaturation of the globulin. The immunoglobulin separated at pH 11.0 and dialyzed to pH 7.4 was reprecipitatable by LDL, and the reactivity did not seem to be appreciably influenced by the alkaline treatment.

Alkalies↗
PubMedDate not supplied

Cavernous hemangioma arising from the lesser omentum: MR findings.

We report the magnetic resonance findings of an unusual hemangioma in the lesser omentum. A well-circumscribed, large mass was identified between the stomach and the left lobe of the liver, with compression of adjacent liver parenchyma. The mass showed low signal intensity (SI) on T1-weighted images, high SI on T2-weighted images with multiple septa, and slightly decreased SI on out-of-phase T1-weighted images. After gadolinium contrast administration, septa within the mass showed minimal enhancement on 30-s T1-weighted images and mild enhancement on 5-min T1-weighted images. The mass was histopathologically diagnosed as a cavernous hemangioma comprised of multiple vascular spaces, fibrotic tissue, and adipocytes.

Adult↗
PubMedDate not supplied

Metallothionein levels in liver and kidney of Canadians--a potential indicator of environmental exposure to cadmium.

Liver and kidney cortex samples were obtained from 89 human autopsies for the determination of metallothionein (MT), cadmium (Cd), zinc (Zn), and copper (Cu). An age-dependent increase of Cd, Zn, and Cd/Zn was observed in the kidney; increases peaked at mid-age and were followed by a decline. Cadmium was present at a low constant level in the liver at all ages. The mean concentrations of Cd and Zn were 18.0 and 40.1 micrograms/g wet weight, respectively, in the kidney, and for the liver the values for Cd and Zn were 2.0 and 79.0 micrograms/g wet weight, respectively. A positive linear relationship was observed between Cd or Zn and MT in the kidney and between Zn and MT in the liver. No other correlation was found between Cu and MT in either organs. Similar values were obtained for MT when estimated by Ag-hem and Cd-hem methods.

Adolescent↗
PubMedDate not supplied

Combination therapy with podophyllin and vidarabine for human papillomavirus positive cervical intraepithelial neoplasia.

Our aim was to establish an effective non-surgical treatment for cervical intraepithelial neoplasia (CIN) through inactivation of human papillomavirus (HPV), the major etiological agent for this disease. We show that vidarabine, a DNA polymerase inhibitor, suppressed growth and HPV gene expression in human cervical keratinocytes immortalized by HPV or in cervical cancer cell lines. Expression of HPV-16 E6 and E7 proteins in normal cervical keratinocytes sensitized cells to apoptosis in the presence of podophyllin or vidarabine. We applied vidarabine ointment and/or podophyllin to cervical epithelium in 28 cases of CIN I-II to evaluate the therapeutic effectiveness of these agents. Co-application of vidarabine and podophyllin in six treatments caused regression of lesions cytologically and histologically, and disappearance of HPV-16 or -18 DNA in 17 of 21 (81%) women. Our results suggest that the combination of vidarabine and podophyllin therapy is an effective non-surgical treatment for HPV-positive CIN.

Adult↗