PubMed Health⌕ Search

Biomedical subjects

J Sasse

Publications and source records attributed to J Sasse.

72 records · Page 4Linked to original sources
PubMed1987

Heparin-binding angiogenesis factors: detection by immunological methods.

Immunological methods for the detection of basic fibroblast growth (FGF) are described. Polyclonal antibodies directed against synthetic peptides representing amino-, internal, and carboxy-terminal regions of basic FGF, were raised in rabbits. Five techniques, enzyme-linked immunosorbent assay, immunoblot, electrophoretic transfer (Western) blot, immunoprecipitation and radioimmunoassay, were used to detect basic FGF. These techniques were used to demonstrate that a human hepatoma cell line synthesizes a growth factor structurally related to brain and pituitary basic FGF.

Angiogenesis Inducing Agents↗
PubMed1986

Purification and characterization of heparin-binding endothelial cell growth factors.

Thirteen endothelial cell growth factors have been purified to homogeneity by heparin affinity and reversed-phase high performance liquid chromatography, and their chromatographic and electrophoretic properties were compared. The amino acid compositions of 10 of these mitogens have also been determined. The results indicate that these heparin-binding growth factors (HBGFs) can be subdivided into two classes. Class 1 HBGFs are anionic mitogens of molecular weight 15,000-17,000 found in high levels in neural tissue and include acidic brain fibroblast growth factor and retina-derived growth factor. Class 2 HBGFs are cationic mitogens of molecular weight 18,000-20,000 found in a variety of normal tissues and are typified by pituitary fibroblast growth factor and cartilage-derived growth factor. Typical class 2 HBGFs have also been isolated from a rat chondrosarcoma, a human melanoma, and a human hepatoma, suggesting that tumors do not make a structurally distinct HBGF class. These results provide a sound basis for the evaluation of the HBGFs purified from a variety of tissues and species and for the delineation of their normal and pathological functions in vivo.

Amino Acids↗
PubMed1986

A cartilage-derived growth factor enhances hyaluronate synthesis and diminishes sulfated glycosaminoglycan synthesis in chondrocytes.

Cartilage-derived growth factor purified to homogeneity by affinity chromatography on columns of heparin-Sepharose was mitogenic for early passage bovine fetal chondrocytes. Hyaluronate and sulfated glycosaminoglycan synthesis in these cells was analyzed by differential enzymatic digestion of the glycosaminoglycans labeled with [14C] glucosamine or [35S]. It was found that chondrocyte proliferation was accompanied by about a four-fold increase in hyaluronate synthesis over a two-day period, while the synthesis of sulfated glycosaminoglycans decreased by about 2-fold. Chromatographic analysis of the sulfated glycosaminoglycans showed decreases in chondroitin 4 and 6 sulfates. It was concluded from these results that cartilage-derived growth factor was a proliferative factor for chondrocytes and differed from the somatomedins.

Animals↗
PubMed1986

Human tumor cells synthesize an endothelial cell growth factor that is structurally related to basic fibroblast growth factor.

A human hepatoma cell line synthesizes, as evidenced by metabolic labeling, an endothelial cell mitogen that is found to be mostly cell associated. The hepatoma-derived growth factor (HDGF) has been purified to homogeneity by a combination of Bio-Rex 70, heparin-Sepharose, and reverse-phase chromatography; it is a cationic polypeptide with a molecular weight of about 18,500-19,000. HDGF is structurally related to basic fibroblast growth factor (FGF). Immunological analysis demonstrates that antiserum prepared against a synthetic peptide corresponding to the amino-terminal sequence of basic FGF cross-reacts with HDGF when analyzed by electrophoretic blotting and by immunoprecipitation. Sequence analysis of tryptic fragments demonstrates that HDGF contains sequences that are homologous to both amino-terminal and carboxyl-terminal sequences of basic FGF.

Amino Acid Sequence↗
PubMed1986

Differential survival of cartilage and muscle cells in chick limb-bud cell cultures maintained in chemically defined and serum-containing media.

Chick limb buds at stages 22-23 largely consist of replicating presumptive chondroblasts and presumptive myoblasts. To study the influence that different medium compositions may have on the survival, replication, and terminal differentiation of these dissociated cells in vitro, micromass cultures were reared in either standard Dulbecco's modified Eagle's medium containing fetal calf serum (SC-DMEM) or in serum-free DMEM. By day 4, approximately 80% and 50% of the original cell inoculum had been lost in DMEM and SC-DMEM cultures, respectively, as estimated from the recovery of incorporated 3H-thymidine. Between days 1 and 4, the total-DNA content remained virtually constant in DMEM cultures, while it increased five- to sixfold in SC-DMEM cultures. In both media, definitive myoblasts and chondroblasts first emerged on day 1 and day 2, respectively, as determined by immunofluorescence staining using antibodies against muscle light meromyosin (LMM) or the major cartilage proteoglycan. In both media, the chondroblasts increased in number and, by day 4, had formed sizable chondroblast nodules. The number of chondroblasts in SC-DMEM cultures exceeded that observed in DMEM cultures. In DMEM, the LMM-positive myoblasts had an atypical morphology and failed to fuse into elongated myotubes; these cells began to degenerate on about day 4, being undetectable by day 8. In SC-DMEM, the numerous LMM-positive myoblasts located in the center of the micromasses also had an atypical morphology, failed to form multinucleated myotubes, and were absent by day 8.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Immunological analysis of chick notochord and cartilage matrix development with antisera to cartilage matrix macromolecules.

Transverse frozen sections from the postcephalic region of stage 9-16 chick embryos and from the wing bud region of stage 17-31 embryos were stained with antibodies to the major extracellular matrix components of cartilage. These probes included unfractionated A1 and A2 antisera to the major cartilage proteoglycan, affinity-purified purified antibodies to the proteoglycan core protein and to Type II collagen, and a monoclonal antibody to keratan sulfate. In embryos as early as stage 10, notochord stained specifically with the keratan sulfate monoclonal antibody. At this stage the notochord, as well as surrounding tissues, were negative to cartilage proteoglycan and collagen antibodies. Positive staining with the latter probes was coordinately acquired by notochord cells and their accompanying sheath around stage 15, while surrounding tissues remained negative. At this stage, the ventral region of the perispinal cord sheath exhibited light staining with the proteoglycan and keratan sulfate antibodies though failing to react to Type II collagen antibodies. Positive staining of notochord and ventral spinal cord persisted through later developmental stages. As revealed by immunofluorescence, definitive vertebral chondroblasts first emerged at approximately stage 23 and definitive limb chondroblasts at stage 25. The results are discussed in terms of the possible multiple roles of notochord in early embryogenesis.

Animals↗
PubMed1984

Separation of precursor myogenic and chondrogenic cells in early limb bud mesenchyme by a monoclonal antibody.

We have addressed the problem of the segregation of cell lineages during the development of cartilage and muscle in the chick limb bud. The following experiments demonstrate that early limb buds consist of at least two independent subpopulations of committed precursor cells--those in (a) the myogenic and (b) the chondrogenic lineage--which can be physically separated. Cells obtained from stage 20, 21, and 22 limb buds were cultured for 5 h in the presence of a monoclonal antibody that was originally isolated for its ability to detach preferentially myogenic cells from extracellular matrices. The detached limb bud cells were collected and replated in normal medium. Within 2 d nearly all of the replated cells had differentiated into myoblasts and myotubes; no chondroblasts differentiated in these cultures. In contrast, the original adherent population that remained after the antibody-induced detachment of the myogenic cells differentiated largely into cartilage and was devoid of muscle. Rearing the antibody-detached cells (i.e., replicating myogenic precursors and postmitotic myoblasts) in medium known to promote chondrogenesis did not induce these cells to chondrify. Conversely, rearing the attached precursor cells (i.e., chondrogenic precursors) in medium known to promote myogenesis did not induce these cells to undergo myogenesis. The definitive mononucleated myoblasts and multinucleated myotubes were identified by muscle-specific antibodies against light meromyosin or desmin, whereas the definitive chondroblasts were identified by a monoclonal antibody against the keratan sulfate chains of the cartilage-specific sulfated proteoglycan. These findings are interpreted as supporting the lineage hypothesis in which the differentiation program of a cell is determined by means of transit through compartments of a lineage.

Animals↗
PubMed1983

Quantal and proliferative cell cycles: how lineages generate cell diversity and maintain fidelity.

There are no known differences between the mechanisms that generate diverse differentiation programs in a mosaic embryo such as Caenorhabdites elegans or in a regulative embryo such as a chick. Transit through an invariant sequence of compartments in a lineage is obligatory for a given precursor cell 1) to inherit its differentiation program from its mother, and 2) to transmit to its daughters, by way of a predetermined binary decision, a new differentiation program. The inheritability of a differentiation program must be encoded in a structural molecule. We postulate that during an S period of a quantal cell cycle, chromosomal structures are so altered that a network of genes that could not be transcribed in the mother becomes available for transcription in the daughters. We do not view as a likely possibility the traditional notion that cell-cell or cell-matrix interactions instruct or commit blank, naive cells to transform into cells with unique differentiation programs. From this perspective, we have initiated experiments to determine the minimal rounds of DNA synthesis, following fertilization, that are required to generate founder cells for several major lineages in the chick. Somewhere between the 15th and 18th generations after fertilization erythrogenic hematocytoblasts that are cytokeratin-positive and vimentin- and hemoglobin-negative undergo a quantal cell cycle. Their daughters are cytokeratin-negative and vimentin- and hemoglobin-positive. DNA synthesis, but not cytokinesis, is an obligatory requirement for this switch in differentiation programs. Essentially similar findings are presented for cells in the cardiogenic, neurogenic, melanogenic, and endothelial lineages. There is no evidence that cell-cell or cell-matrix interactions are required for this diversification. Such interactions, however, may be required for the large number of proliferative cell cycles within particular compartments of particular lineages that are characteristic of all growing or expanding systems. With respect to classical "CFU cells" it is of interest that definitive white blood cells have not yet been identified in these cultures. Lastly, the high ratio of primitive red blood cells to non-red blood cells in the first 40 hours of culture is consistent with the notion that the majority of all cells present in the blastodisc at these early stages are in fact already committed to a unipotent erythrogenic lineage [5, 18, 23, 44, 45]. The issue of changing ratios of cells within compartments of a lineage, as well as of cells in different lineages, is much neglected in consideration of (a) normal embryogenesis, (b) cell-renewal in mature organisms and, particularly,

Animals↗
PubMed1978

Synthesis and extracellular deposition of fibronectin in chondrocyte cultures. Response to the removal of extracellular cartilage matrix.

Fibronectin, the major cell surface glycoprotein of fibroblasts, is absent from differentiated cartilage matrix and chondrocytes in situ. However, dissociation of embryonic chick sternal cartilage with collagenase and trypsin, followed by inoculation in vitro reinitiates fibronectin synthesis by chondrocytes. Immunofluorescence microscopy with antibodies prepared against plasma fibronectin (cold insoluble globulin [CIG]) reveals fibronectin associated with the chondrocyte surface. Synthesis and secretion of fibronectin into the medium are shown by anabolic labeling with [35S]methionine or [3H]glycine, and identification of the secreted proteins by immunoprecipitation and sodium dodecyl sulfate (SDS)-disc gel electrophoresis. When chondrocytes are plated onto tissue culture dishes, the pattern of surface-associated fibronectin changes from a patchy into a strandlike appearance. Where epithelioid clones of polygonal chondrocytes develop, only short strands of fibronectin appear preferentially at cellular interfaces. This pattern is observed as long as cells continue to produce type II collagen that fails to precipitate as extracellular collagen fibers for some time in culture. Using the immunofluorescence double-labeling technique, we demonstrate that fibroblasts as well as chondrocytes which synthesize type I collagen and deposit this collagen as extracellular fibers show a different pattern of extracellular fibronectin that codistributes in large parts with collagen fibers. Where chondrocytes begin to accumulate extracellular cartilage matrix, fibronectin strands disappear. From these observations, we conclude (a) that chondrocytes synthesize fibronectin only in the absence of extracellular cartilage matrix, and (b) that fibronectin forms only short intercellular "stitches" in the absence of extracellular collagen fibers in vitro.

Cartilage↗
PubMedDate not supplied

Role of basic fibroblast growth factor in prostatic tumors.

Compared with normal prostatic tissue, the level of basic fibroblast growth factor (bFGF) is elevated in prostatic tumors. This suggests that bFGF may play a role in the development of prostatic neoplasms. The current study was undertaken to identify the cellular distribution of bFGF in benign prostatic hyperplasia (BPH) and prostatic carcinoma using a polyclonal antiserum against recombinant bFGF. In paraffin sections of prostatic tumors immunoreactive bFGF was found in fibroblasts, smooth muscle cells, and endothelial cells. Distinct staining was seen in most nuclei of these cells and a less intense immunoreaction occurred in the cytoplasm of smooth muscle cells. No immunostaining was seen in prostatic epithelial cells of prostatic tumors whether benign or malignant. With digoxigenin-labeled oligonucleotides in nonradioactive in situ hybridization, the presence of mRNA for bFGF was shown in smooth muscle cells of the stroma, suggesting that these cells are the main source of bFGF in BPH. Because no immunostaining for bFGF was obtained in the carcinoma cells, a specific role for bFGF cannot be seen for the development of malignant prostatic tumors.

Base Sequence↗