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Biomedical subjects

M C Wu

Publications and source records attributed to M C Wu.

At least 163 records · Page 9Linked to original sources
PubMed1981

Establishment and cell cycle kinetics of a human squamous cell carcinoma in nude mice and in vitro.

A human squamous cell carcinoma of the virus was xenografted to athymic, nude mice. A tissue culture cell line designated SqCaVu-1H was derived from a second-passage xenograft. The growth characteristics and cell cycle kinetics in the xenografts and in SqCaVu-1H cells were compared. Approximately 80% of the tumor implants produced growing xenografts which had a 2-week latent period followed by Gompertzian growth with a doubling time of 5 to 30 days at 35 days postimplantation. The cell cycle kinetics of the xenografts revealed a heterogeneity from region to region within the tumor. G2 phase and S phase in the xenografts are approximately 8 and 13 hr, respectively. The SqCaVu-1H cells contain only human chromosomes. The modal chromosome number was 64. SqCaVu-1H cells produce plasminogen activator during logarithmic growth, and they produce tumors when injected s.c. into athymic, nude mice. Logarithmically growing SqCaVu-1H cells have a population-doubling time of 21.8 hr in tissue culture. In vitro, their cell cycle duration is approximately 16.0 hr, with G2 phase at 5.6 hr and S phase at 8.6 hr. Comparison of the growth of the same human tumor cells under in vivo and in vitro conditions serves to emphasize that tumor cell proliferation depends strongly on the microenvironment. The varied proliferation characteristics are correlated with their varied inhibition of deoxyuridine incorporation into DNA because of exposure to methotrexate. Logarithmically growing SqVaCu-1H cells had a 50% inhibitory dose of 2.2 X 10(-6) M. Plateau-phase cells in vitro had a 50% inhibitory dose of 9 X 10(-6) M, while the inhibition of cells from the xenografts was nearly dose independent.

Animals↗
PubMed1980

Granulocyte and macrophage colony-stimulating factor from human placenta conditioned medium.

Conditioned medium prepared from human placenta tissue stimulates in vitro colony formation by mouse and human marrow cells. At least two types of colony-stimulating activities are found and can be separated by isoelectrofocusing. The first type of colony-stimulating factor (CSF) shows heterogeneity on isoelectrofocusing with pI in the range of 3.6-4.7. It has been purified 10(5)-fold by hydroxylapatite chromatography, preparative isoelectrofocusing, gel filtration, polyacrylamide gel isoelectrofocusing, and electrophoresis to a specific activity of 7.5 X 10(7) units/mg. The purified CSF shows a single band on microgel electrophoresis and stimulates mostly mouse macrophage colony formation. It has a molecular weight of 41 000 as determined by gel filtration and is sensitive to proteolytic enzyme digestion and periodate oxidation. Treatment with neuraminidase is without effect on activity. It is stable at pH 5-10 and 60 degrees C for 30 min. The second type of CSF appears as a single activity peak on isoelectrofocusing with a pI of 5.7. The molecular weight is calculated to be 27 000 from gel filtration. It is very sensitive to trypsin and periodate but inert to neuraminidase or mercaptoethanol treatment. It is stable at neutral pH but labile at 60 degrees C for 30 min. The purified CSF stimulates predominantly granulocytic colony formation from human marrow cells.

Animals↗
PubMed1980

Common pattern of two distinct types of colony-stimulating factor in human tissues and cultured cells.

Conditioned media prepared from human lung, placenta, peripheral leukocytes, cultured human pancreatic carcinoma cells, and cultured cervical carcinoma cells exhibit a common pattern of two distinct colony-stimulating factors (CSF) separable by isoelectrofocusing. Type I CSF appears polydisperse on isoelectrofocusing, showing multiple peaks with an isoelectric point of 3.6-4.7 and mol wt 50,000. It has a much higher activity in mouse than in human bone marrow, and stimulates the formation of predominately macrophage colonies. Type II CSF has an isoelectric point of 5.7 and mol wt 27,000 and exhibits higher activity in human than in mouse marrow, yielding predominately granulocytic colonies.

Animals↗
PubMed1980

Antibody to purified human colony-stimulating factor: use in the identification and isolation of granulocyte macrophage progenitor cells.

Conditioned media prepared from human lung, placenta, peripheral leukocytes, cultured human pancreatic carcinoma cells, and cultured cervical carcinoma cells exhibit a common pattern of two distinct types of colony-stimulating factors (CSF) separable by isoelectrofocusing. Type I and type II CSF differ in MW, isoelectric point, CFU-C specificity, and the morphologic type of colonies they stimulate. Type I CSF exhibits higher activity in mouse than in human marrow while type II is more active in human marrow. Type I and II CSF from cultured human pancreatic carcinoma have been purified, type I to apparent homogeneity, and antibody has been prepared against them in rabbits. We have utilized purified CSF and anti-CSF antibodies to label CFU-C fluorescently for the purpose of cell sorting via flow photometry. Human bone marrow cells preincubated with CSF and then treated first with anti-CSF antibody then fluorescein-labeled goat antirabbit globulin retain their ability to grow and form aggregates in the presence of additional CSF. Colonies thus formed exhibit fluorescence, the intensity of which diminishes with increase in aggregate size. These observations provide new insight into the biology of CFU-C and suggest the following: (1) Incubation of marrow cells with CSF for 2 h results in binding of CSF or an antigenic component of CSF to membranes of CFU-C. (2) Bound CSF-anti CSF complex remains on CFU-C membranes through at least 5-6 cell divisions. (3) The approach described offers great potential for the preparation of highly purified CFU-C populations by fluorescence cell sorting.

Antibodies↗
PubMed1978

Purification and characterization of a colony stimulating factor from human lung.

Conditioned medium prepared from human autopsy lung tissue contains high level activity of colony stimulating factor which stimulates granulocytes and macrophage colony formation in both mouse and human bone marrow. The lung colony stimulating factor has been purified about 2250-fold by methods including hydroxylapatite chromatography, preparative gel electrophoresis, preparative isoelectric focusing, and gel filtration chromatography. The final specific activity was 2.7 X 10(6) units/mg. The purified factor has a molecular weight of 41 000 as determined by gel filtration. It is stable at the pH range of 6.5--10 and 56 degrees C for 30 min but sensitive to protease digestion and periodate oxidation. On polyacrylamide gel electrophoresis, it migrates in the alpha-globulin post-albumin region. Upon isoelectrofocusing lung colony stimulating factor appears heterogeneous with isoelectric points of 3.7--4.3. Treatment with neuraminidase did not affect its activity, but caused a change in electrophoretic mobility and isoelectric point. Antibody produced by immunizing rabbits with partially purified lung colony stimulating factor exerted strong inhibitory activity on the factor from lung as well as on colony stimulating factor from other human sources including serum, urine, and placenta.

Animals↗
PubMed1978

Mechanism of sensitivity of cultured pancreatic carcinoma to asparaginase.

The effects of E. coli L-asparaginase on cultured human pancreatic carcinoma (MIA PaCa-2) have been studied. The enzyme (1 U/ml) inhibited growth and protein synthesis in both MIA PaCa-2 and PANC-1, another pancreatic carcinoma cell line, but had little or no effect on human breast carcinoma or melanoma cells. The inhibition of protein synthesis by E. coli L-asparaginase was largely reversed by L-glutamine but not by L-asparagine. The growth of both MIA PaCa-2 and PANC-1 showed absolute dependence on L-glutamine. These results indicate that the effect of E. coli L-asparaginase on cultured pancreatic carcinoma cells is exerted at least in part through its L-glutaminase activity. Although the addition of L-glutamine to the culture appeared to prevent cell death caused by L-asparaginase, it did not restore the ability of the cells to proliferate. Asparaginase derived from vibrio succinogenes, which is virtually free of L-glutaminase activity, was equally inhibitory to MIA PaCa-2 cell growth but did not affect protein synthesis. It is concluded that the inhibition of growth of cultured pancreatic carcinoma cells by E. coli asparaginase is a combined function of both its L-asparaginase and L-glutaminase activity.

Amino Acids↗
PubMed1977

The isolation and characterization of a colony stimulating factor from human lung.

Serum-free conditioned medium from human lung obtained at autopsy provides a rich source of colony stimulating factor which stimulates granulocytic and macrophagic colony growth in both mouse and human bone marrow. The appearance of the factor is enhanced by endotoxin and inhibited by either puromycin or actinomycin D. Human lung colony stimulating factor is stable at the pH range of 6.5-10 and temperature of 56 degrees C for 30 min. It is resistant to trypsin and neuraminidase but is sensitive to subtilisin, chymotrypsin and periodate. It shows heterogeneity on Sephadex gel filtration with two activity peaks having molecular weight of 200 000 and 40 000, respectively. Upon gel electrophoresis, human lung colony stimulating factor migrates in the alpha-globulin post-albumin region. Using the combination procedures of hydroxyapatite chromatography and preparative polyacrylamide gel electrophoresis a 600-fold purification was achieved with a final specific activity of 6-10(5) units per mg protein. The purified colony stimulating factor is very labile; however, the activity can be stabilized by the addition of gelatin or bovine serum albumin at the concentration of 0.1% and 0.2 mg/ml, respectively.

Chromatography↗