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L B Chen

Publications and source records attributed to L B Chen.

At least 145 records · Page 8Linked to original sources
PubMed1984

Localization of endoplasmic reticulum in living and glutaraldehyde-fixed cells with fluorescent dyes.

Certain fluorescent dyes, previously reported to localize mitochondria, when used at higher concentrations also localize a continuous net-like structure in both living and glutaraldehyde-fixed cells. A similar reticular structure can be detected by phase-contrast microscopy and whole-mount electron microscopy in potassium permanganate-fixed cells as well. This structure is mostly tubular, with some patch-like areas, and is likely to be the endoplasmic reticulum (ER). The organization of the reticular structure is sensitive to colchicine and rotenone but not to cytochalasin B, taxol, monensin, the calcium ionophore A23187, 12-O-tetradecanoylphorbol 13-acetate, or hydrocortisone.

Animals↗
PubMed1984

Keratin antibody localization in head and neck tissues and neoplasms.

Immunohistochemical staining for keratin proteins may be useful as a diagnostic parameter in head and neck neoplasms. Our study evaluates the keratin antibody staining properties of normal tissues as well as neoplastic and non-neoplastic head and neck lesions from surgical procedures performed on 100 patients. The results indicate that the anti-keratin antibody technique can be helpful in several areas of head and neck pathology.

Antibodies↗
PubMed1984

Direct effect of gossypol on TR-ST cells: perturbation of rhodamine 123 accumulation in mitochondria.

Gossypol has deleterious effects directly on TR-ST cells originating from a rat testicular tumor. Exposure of TR-ST cells to gossypol (5 micrograms/ml) decreases their rate of protein synthesis approximately 30% within 1 h and 65% by greater than 10 h, causes intracellular vacuolation, changes cell shape from cobblestone to a rounded conformation and inhibits cell proliferation. Yet, these gossypol-treated cells remain viable, as assessed by their ability to hydrolyze fluorescein diacetate. Gossypol also perturbs mitochondrial transmembrane potential in TR-ST cells, as demonstrated by marked changes in rhodamine 123 staining. Mitochondria of control TR-ST cells avidly accumulate rhodamine 123, but those in cells exposed to gossypol (greater than or equal to 5 micrograms/ml) for greater than 1 h fail to sequester the fluorochrome. Instead, the cell cytoplasm shows a light and diffuse staining with rhodamine 123. Rat spermatozoa show a similar response. Conversely, at concentrations of 20 micrograms/ml, gossypol has minimal effects on rhodamine 123 accumulation by primary cultures of hepatocytes and by rat spermatogenic cells, including primary spermatocytes and spermatids (Steps 1-12). Moreover, TR-ST cells exhibit reduced mitochondrial staining with gossypol at an ED50 of 7.6 micrograms/ml, while those for the nontesticular Rat-1, AnAn, 3T3 and PtK2 cell lines are 13.1, 21.5, 28.5 and 26.4 micrograms/ml, respectively.

Animals↗
PubMed1984

A monoclonal antibody recognizing a keratin filament protein in a subset of transitional and glandular epithelia.

Monoclonal antibodies were raised against the detergent-insoluble cytoskeletal fraction of the human bladder carcinoma cell line, EJ. By immunofluorescence, one of these antibodies, H10-1, localized to keratin filaments in EJ and three out of five other transitional-cell carcinoma lines. Primary normal-human urothelial cells in culture were not recognized by H10-1. Strong staining of keratin filaments was also seen in 11 human adenocarcinoma cell lines, but it was only seen in a subpopulation of cells in one out of four squamous-cell carcinoma lines and not at all in two normal diploid human epidermal keratinocyte strains. Immunofluorescence on frozen sections of mouse, human, and rabbit tissues showed that H10-1 recognized the upper layer of the transitional epithelium of mouse and rabbit bladder, and a subset of simple epithelia (mouse stomach glands and some colon mucosal glands, but not kidney tubules, small intestine, ovary germinal epithelium, or endometrium; some human colon mucosal glands and glandular breast epithelium, but not endometrium). The antigen which is recognized by this antibody was not detected in examples of stratified squamous epithelium (mouse skin, nonglandular stomach, or esophagus; human skin, esophagus, or rectum) or nonepithelial tissue. On frozen sections of human tumors, the H10-1 antibody recognized 9 out of 14 colon carcinomas and 4 out of 6 breast carcinomas but did not recognize two sarcomas or a melanoma. This antibody apparently does not recognize its antigen in the presence of sodium dodecyl sulfate (SDS) because brief exposure of methanol-fixed cells to 0.1% SDS reversibly inhibited the binding of the H10-1 monoclonal antibody to keratin filaments by immunofluorescence, even when the binding of a rabbit polyclonal antikeratin antibody was unaffected. Two-dimensional gel-electrophoretic analysis of keratin-enriched fractions which had been isolated from various cell lines disclosed a good correlation between the presence of a 47-kdalton, pI-5.35 polypeptide and positive immunofluorescence with this antibody. These observations suggest that a certain keratin or keratin-associated protein is specifically expressed in a subpopulation of transitional and simple epithelial cells, and cultured cells derived from these epithelia. The monoclonal antibody described here may therefore be useful for increasing the precision of histological classification of epithelia, as well as the verification of the origin of certain cultured cell lines.

Animals↗
PubMed1984

Immunohistochemical study of nasopharyngeal carcinoma using monoclonal keratin antibodies.

Nasopharyngeal carcinoma (NPC) provides a unique opportunity to evaluate distinctive epidemiologic features and a possible etiologic relationship with Epstein-Barr virus (EBV) in human malignancy. The lack of a uniformly accepted pathologic classification for NPC has limited the application of this data, although the World Health Organization (WHO) developed a classification that may solve this problem. Monoclonal keratin antibodies were used for staining of NPC for evaluation of its assistance in diagnosis and classification. In the present immunohistochemical study, monoclonal keratin antibodies, designated AE1, AE2, and AE3, and a polyclonal keratin antibody (RAK) were used for study of the presence of keratin in 121 cases of NPC obtained from China and the United States. AE1 monoclonal antibody, which recognizes keratin protein classes 56.5K, 50K, and 40K, was shown to be the most sensitive and specific for NPC tumor cells among the keratin antibodies studied. In addition, some different keratin expression patterns could be identified between different kinds of epithelium and different tumor groups, with possible relevance to the histogenesis of the histologic subtypes of NPC.

Antibodies, Monoclonal↗
PubMed1983

Anticarcinoma activity in vivo of rhodamine 123, a mitochondrial-specific dye.

Carcinoma cells and normal epithelial cells differ in the mitochondrial retention of a permeant cationic compound, rhodamine 123. The possibility of utilizing this difference in carcinoma chemotherapy was investigated. Rhodamine 123 exhibited anticarcinoma activity in mice, and this activity was potentiated by 2-deoxyglucose.

Animals↗
PubMed1983

Characterization of a phosphotyrosyl protein phosphatase activity associated with a phosphoseryl protein phosphatase of Mr = 95,000 from bovine heart.

A cytosolic phosphoprotein phosphatase of Mr = 95,000 purified from bovine cardiac muscle, which contains a catalytic subunit of Mr = 35,000, is known to be associated with a Mg2+-activated p-nitrophenyl phosphatase activity. We have found that the enzyme preparation is also active toward phosphotyrosyl-IgG and -casein phosphorylated by pp60v-src, the transforming gene product of Rous sarcoma virus. The properties of this phosphotyrosyl protein phosphatase activity closely resemble those of the p-nitrophenyl phosphatase activity but sharply differ from those of the phosphorylase phosphatase activity. Comparative studies of the activities of the Mr = 95,000 phosphatase, bovine kidney alkaline phosphatase, and ATP X Mg-dependent phosphatase toward phosphoseryl, phosphothreonyl, and phosphotyrosyl proteins and p-nitrophenyl phosphate under various conditions have been carried out. The results indicate that the Mr = 95,000 enzyme exhibits higher activity toward phosphoseryl and phosphothreonyl proteins than toward phosphotyrosyl proteins, while the kidney alkaline phosphatase preferentially dephosphorylates phosphotyrosyl proteins. ATP X Mg-dependent phosphatase is inactive toward phosphotyrosyl proteins.

Animals↗
PubMed1983

Photoelectron microscopy and immunofluorescence microscopy of cytoskeletal elements in the same cells.

Pt K2 rat kangaroo epithelial cells and Rat-1 fibroblasts were grown on conductive glass discs, fixed, and permeabilized, and the cytoskeletal elements actin, keratin, and vimentin were visualized by indirect immunofluorescence. After the fluorescence microscopy, the cells were postfixed and dehydrated for photoelectron microscopy. The contrast in these photoelectron micrographs is primarily topographical in origin, and the presence of fluorescent dyes at low density does not contribute significantly to the material contrast. By comparison with fluorescence micrographs obtained on the same individual cells, actin-containing stress fibers, keratin filaments, and vimentin filaments were identified in the photoelectron micrographs. The apparent volume occupied by the cytoskeletal network in the cells as judged from the photoelectron micrographs is much less than it appears to be from the fluorescence micrographs because the higher resolution of photoelectron microscopy shows the fibers closer to their true dimensions. Photoelectron microscopy is a surface technique, and the images highlight the exposed cytoskeletal structures and suppress those extending along the substrate below the nuclei. The results reported here show marked improvement in image quality of photoelectron micrographs and that this technique has the potential of contributing to higher resolution studies of cytoskeletal structures.

Actins↗
PubMed1983

Behavior of cells seeded in isolated fibronectin matrices.

Cell-free fibronectin matrix (FN-matrix) isolated from chick embryo fibroblasts was used to study cell-matrix interaction. After 24 h, most fibroblastic cells, including those without cell surface fibronectin, adopted bipolar fusiform morphology. Cells grew in parallel arrays and aligned with each other apparently along FN-matrix. Since the orientation of fibronectin fibers was determined by chick embryo fibroblasts, our results suggested that intercellular organization of "matrix-using" cell type may be influenced by "matrix-producing" cell type. Whereas the elongation and alignment effects induced by FN-matrix have been detected in fibroblasts (both normal and transformed), myoblast, aortic endothelial cells, neural cell lines (B103 and RT4D1), and cardiac muscle cells, similar effects are not detected in bone marrow hemopoietic cells, circulating lymphocytic T and B cells, and sympathetic neurons. For epithelial cells, FN-matrix has varying effects. Elongation and alignment effects are detected only in transformed epithelial cells with a great reduction in keratin expression. The morphology of normal or transformed epithelial cells with abundant keratin appears unaffected by FN-matrix. FN-matrix reduced the growth of several transformed fibroblastic lines up to 25%, but did not restore the appearance of actin stress fibers and the normal migratory activities of Rous sarcoma virus-transformed rat cells.

Animals↗
PubMed1983

Effect of microtubules and intermediate filaments on mitochondrial distribution.

The laser dye rhodamine 123 specifically stains mitochondria in living cells and facilitates the observation of changes in mitochondrial distribution in single cells under a variety of experimental conditions. Visualization of mitochondria in a number of cell lines followed by processing of these cells to study different cytoskeletal elements by indirect immunofluorescence, revealed good but not absolute correlation between mitochondria and microtubules or intermediate filaments. Mitochondria and microfilament distribution within the same cell did not show such a correlation. On the basis of observations made by various experimental approaches, we suggest that mitochondrial distribution is under the strong influence of the two systems, microtubules and intermediate filaments. Neither plays an absolute role but one seems able to play a more dominant role in the absence of the other.

Animals↗
PubMed1983

Selective toxicity of rhodamine 123 in carcinoma cells in vitro.

The study of mitochondria in situ has recently been facilitated through the use of rhodamine 123, a mitochondrial-specific fluorescent dye. It has been found to be nontoxic when applied for short periods to a variety of cell types and has thus become an invaluable tool for examining mitochondrial morphology and function in the intact living cell. In this report, however, we demonstrate that with continuous exposure, rhodamine 123 selectively kills carcinoma as compared to normal epithelial cells grown in vitro. At doses of rhodamine 123 which were toxic to carcinoma cells, the conversion of mitochondrial-specific to cytoplasmic-nonspecific localization of the drug was observed prior to cell death. At 10 microgram/ml, greater than 50% cell death occurred within 7 days in all nine of the carcinoma cell types and lines of different origin studied, while six of six normal epithelial cell types and lines remained unaffected. Cotreating carcinoma cells with 2-deoxyglucose and rhodamine 123 enhanced the inhibition of growth by rhodamine 123 alone in clonogenic survival assays. The observation of the selective toxicity of rhodamine 123 appears to be unique in view of the absence of selective toxicity reported in vitro for the various antitumor agents currently in clinical use. Preliminary results with rhodamine 123 in animal tumor systems indicate antitumor activity for carcinomas.

Animals↗
PubMed1982

Rhodamine-123 selectively reduces clonal growth of carcinoma cells in vitro.

Rhodamine-123, a cationic laser dye, markedly reduced the clonal growth of carcinoma cells but had little effect on nontumorigenic epithelial cells in vitro. This selective inhibitory effect of Rhodamine-123 on some carcinomas is unusual since known anticancer drugs, such as arabinosyl cytosine and methotrexate, have not been shown to exhibit such selectivity in vitro.

Animals↗
PubMed1982

Monitoring the effect of anti-cancer drugs on L1210 cells by a mitochondrial probe, rhodamine-123.

The cancer chemotherapeutic agents 1-beta-D-arabinofuranosylcytosine (Ara-C), methotrexate, and 5-fluorouracil cause a rapid loss of mitochondrial Rh-123 uptake in L1210 cells, which correlates with the loss of clonogenic ability. The loss of Rh-123 uptake is irreversible and occurs prior to Trypan Blue staining. Thus, the antimetabolites, unlike freeze-thawing and detergent treatments, generally cause mitochondrial damage prior to changes in plasma membrane permeability. Since the effect of antimetabolites on Rh-123 uptake is maximal at 24 h, the Rh-123 assay may provide a rapid alternative to the clonogenic assay for monitoring the cytotoxic effects of these drugs. Our results also suggest that the inhibition or impairment of mitochondrial function may be an important step in the cytocidal and/or cytostatic action of anti-cancer drugs.

Animals↗