Biomedical subjects

C Q Zeng

Publications and source records attributed to C Q Zeng.

22 records · Page 2Linked to original sources

PubMed1992

Characterization of a lung-cancer-associated auto-antigen.

An antigen, protein X (Px), was purified from immune complexes isolated from malignant pleural effusions from patients with adenocarcinoma of the lung by EDTA treatment, PEG 8000 precipitation, protein A affinity chromatography, and Sephadex G-200 separation in the presence of 3 M NaCl. The purified antigen had a M(r) 17,000 by SDS-PAGE, and consisted of isoelectric species of pI 6.3 and 6.6. Purified Px recombined with Ig isolated from pleural fluids from patients with lung adenocarcinoma, but not with Ig from patients with breast carcinoma. Using an autologous human and heterologous chicken antibody, Px was found, by immunohistology, in the cytoplasm of some of the well-differentiated lung adenocarcinoma cells, but was not seen in normal lung or a variety of other malignant tissues. A liquid-phase competitive-inhibition RIA was developed. Over 30 ng/ml of Px were found in 9 of 15 pleural fluids from patients with lung carcinoma, none of 20 from patients with breast, ovary, stomach or colon cancer, and in 3 of 15 patients with unknown primary tumor. Our data suggest that Px may be a lung-cancer-associated autoantigen which can elicit a host humoral response in vivo.

Antigen-Antibody Complex↗

PubMed1992

Isolation and partial characterization of a specific alpha-fetoprotein receptor on human monocytes.

Since a large body of data has suggested a significant role for alpha-fetoprotein (AFP) in the regulation of the immune response at a number of levels, we examined the possibility of a specific receptor for AFP on the immune recognition cell, the monocyte/macrophage. Microscopic autoradiography exhibited an obvious binding of AFP almost exclusively on human peripheral monocytes but not on lymphocytes. In a human monocyte cell line (U937) Scatchard plot analysis indicated the presence of two distinct AFP-specific binding sites with a Kd of 5 x 10(-11) M, 49 binding sites per cell, and 2.5 x 10(-7) M, 7,800 binding sites per cell. 125I-ASD-AFP, AFP-radiolabeled bifunctional photoactivatable thio-cleavable cross-linker, was used to isolate the AFP binding protein from U937 cells. After ultraviolet photoactivation, 125I-sulfosuccinimidyl 2-(p-azido-salicylamido)ethyl-1,3'-dithiopropionate was covalently linked to the putative receptor. Autoradiography of SDS gradient PAGE under reducing conditions showed a major radiolabeled band at between 62 and 65 kD. To confirm the specificity of the finding, recombination of AFP with the isolated receptor was examined in artificially reconstituted membrane vesicles, which also resulted in a single band at approximately 62-65 kD by SDS-PAGE autoradiography. From the data above, we concluded that human monocytes possess a specific AFP binding protein on the membrane, a putative receptor, which may be involved with the physiological regulation of the immune response.

Cell Line↗

PubMed1989

A novel approach to experimentally estimating the number of reactive epitopes on multivalent antigens.

Various coefficients in radioimmunoassays are expressed in a series of equations. These equations provide an approach to estimating the number of epitopes on a multivalent antigen as well as a macromolecular topogram. In this paper, pig insulin (Ins), horse myoglobin (Mb), human serum albumin (HSA), human alpha-fetoprotein (AFP) and adr-hepatitis B type virus surface antigen (HBsAg) were chosen as objects of study. The number of epitopes was calculated to be Ins = 2, Mb = 5, HSA = 16, AFP = 6, HBsAg = 146. These epitope numbers, calculated by equations, were very similar to those previously identified experimentally. This suggests that our theoretical approach may be useful in predicting the number of epitopes on other macromolecules of biological and clinical interest.

Animals↗

PubMed1988

Microtubule and microfilament distribution and tubulin content in the cell cycle of Indian muntjac cells.

Using DAPI, rabbit antitubulin antibody, FITC-labeled goat anti-rabbit IgG, and TRITC-phalloidin to stain individual cells, the microspectrophotometric analysis showed that three markers that represent the nucleus, microtubules (MT), and microfilaments (MF), respectively, could be recognized in individual cells without interference. The phase of the cell cycle was determined by DNA content. We found that in Indian muntjac (IM) cells, the amount of tubulin in G2 and M phases was about twice as much as that in G1 phase. In G2 cells, the cytoplasmic microtubule complex (CMTC) became denser than in G1 cells. The cytoplasmic MT extent in basically the same orientation as MF bundles in interphase. The regions where the MT is denser also have a denser MF distribution.

Actin Cytoskeleton↗