ISSN:0021-9541    

DOI:10.1002/jcp.1041130504

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

ISSN:0021-9541    

DOI:10.1002/jcp.1041130505

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractThe achievements of The Wistar Institute during the 25 years of Hilary Koprowski's directorship really need no memorial because they constitute a substantial part of the corpus of recorded scientific knowledge. All the same it is a particular pleasure to help commemorate a remarkable man and place.

ISSN:0021-9541    

DOI:10.1002/jcp.1041130506

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

ISSN:0021-9541    

DOI:10.1002/jcp.1041130507

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

ISSN:0021-9541    

DOI:10.1002/jcp.1041130508

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractSome cells of the established preadipose cell line, 3T3‐L1, synthesize triglyceride after becoming confluent and quiescent. An analysis of the distribution of clusters of lipid‐containing cells was consistent with a commitment event during exponential growth followed by clonal growth of committed cells. Experiments were designed to determine if the final clonal pattern of fat among nonfat cells could be described by a probbility model. Undifferentiated cells (fibroblastic cells with no detectable accumulation of triglycerides) were plated at various cell numbers so that the total number of cell divisions to confluence could be controlled. Cells were passaged by trypsinization and replating, or trypsinization followed by passage through a narrow‐bore needle before replating. Passing cells through a 22G needle seems to eliminate already committed cells from the population. We determined the percentage of fat cells and the range of clone sizes in cultures in which clone sizes depended upon the number of allowed cell divisions. Patterns of clone sizes depended upon the number of allowed cell divisions. Patterns obtained by computer simulations of several programmed and stochastic commitment models, both the observed range of clone sizes and pattern of clones can be approximated by a simple stochastic model, suggesting that commitment to fat production in 3T3‐L1 cells is a random process occurring with a fixed probability in single cells in exponential growth, followed by division of both committed and uncommitted cells. The probability of commitment was essentially constant at each cell division. The number of cells committed during each passage is just large enough to replace “terminally differentiated” lipidcontainig cells that have been lost, thereby maintaining a constant percentage of fat cells in any given cultur

ISSN:0021-9541    

DOI:10.1002/jcp.1041130509

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractWe have analyzed chromosomal proteins extracted from murine teratocarcinoma‐derived stem cell lines (F9 and 12‐1) and from their differentiated derivatives (12‐1a) because of the differential sensitivity to DNase I digestion of these two cell types. The chromosomal DNA of stem cells is more sensitive to DNase I digestion than that of differentiated cells. Stem cell core histones are more highly acetylated than their differentiated counterparts, and certain high‐mobility group (HMG) proteins from stem cells (HMG 1 and HMG 2) are found in greater amounts than in the differentiated cells though others (HMG 14 and HMG 17) occur in similar amounts. We have also identified a new HMG protein (HMG 9) that is present in stem cells and is lost following differen

ISSN:0021-9541    

DOI:10.1002/jcp.1041130510

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractWe have established three hybridoma cell lines (designated EBI‐1, ‐2, and ‐3) secreting immunoglobulin G (IgG) antibodies specific for human alpha‐interferon (HuIFN‐α) by fusing P3X63Ag8.6.5.3 myeloma cells with spleen cells of mice immunized with human “lymphoblastoid” (NC‐37) interferon (IFN). The antibodies were used to study the antigenic diversity of a number of IFNs derived from blood leukocytes and lymphoid cell lines. When incubated with 10 U of IFN, EBI‐1 antibodies completely neutralized the antiviral activity of HulFN‐αrA produced inE colias well as of IFN produced spontaneously in several lymphoblastoid cell lines. In contrast, only 60‐70% of alpha‐interferon (IFN‐α) induced in leukocytes, lymphoma, or lymphoblastoid cell lines by Sendai virus or poly (l):(C) could be neutralized by the antibody; furthermore, IFN‐α produced spontaneously in bromodeoxyuridine‐treated lymphoma cells was also only partially neutralized. EBI‐2 and EBI‐3 antibodies were tested against a smaller set of samples and found to react similarly. Our result indicate that human IFN‐α subtypes can be grouped into at least two antigenically distinguishable subsets, one of which being represented by IFN‐αA, and that these subsets can be expressed differently unde

ISSN:0021-9541    

DOI:10.1002/jcp.1041130511

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractMurine embryonal carcinoma (EC) cells fail to express viral T antigen following infection with polyoma (Py) virus, while some differentiated derivatives are fully susceptible to viral infection. The block to expression in EC cells apparently occurs after adsorption and penetration but prior to the synthesis of early viral proteins. The F9 EC cell line was employed to further investigate the failure of Py gene expression in EC cells as well as the viral susceptibility of certain differentiated cell types. F9 cultures treated with retinoic acid (RA) or RA in combination with dibutyryl cAMP (dBcAMP) are quantitatively induced to differentiate to endodermal cell types. When the fate of the viral DNA was examined in F9 EC cells, free viral DNA was observed early after infection but was eventually lost with continued cell growth. Cultures induced to differentiate in the presence of RA demonstrated limited viral susceptibility which increased with prolonged RA exposure. Polyoma sensitivity did not directly parallel basement membrane antigen production, a marker used to distinguish this differentiated endodermal cell type. Viral gene expression could be obtained if Py DNA was introduced into the cells prior to RA induction. In contrast, the endodermal progeny derived from a dual treatment with RA plus dBcAMP appeared highly refractory to Py infection.

ISSN:0021-9541    

DOI:10.1002/jcp.1041130512

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractMouse anti‐chicken monoclonal antibodies were raised against an avian myeloblastosis virus (AMV)‐transformed myeloblastic leukemic cell line. One monoclonal antibody, S1‐37 (lgG2a), reacted with producer and nonproducer myeloblastic leukemia cell lines transformed by AMV and by E‐26 virus, but it did not react with chicken fibroblasts infected with RAV‐2, MAV‐2, MAV‐1, or RAV‐7, S1‐37 also did not react with normal chicken hemopoietic cells, except for yolk sack macrophages and a small population of embryonal and adult bone marrow cells that morphologically resembled macrophages.Cytotoxicity studies of GM‐CFU, the normal stem cell population of the granulocytic macrophage lineage, indicated that these cells lack the surface antigen recognized by S1‐37. Immunoprecipitation studies of125I surfacelabeled myeloblastic leukemic cells indicated that S1‐37 binds a 42,000 Mr polypeptide. The possible role of this polypeptide in the process of transformation and differentiation of chicken mye

ISSN:0021-9541    

DOI:10.1002/jcp.1041130513

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY