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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

53 Lewis lung carcinomas implanted subcutaneously into C57BL/6-mice were examined. The animals were killed at various stages of tumor growth (TG) and prepared for histology and for scanning electron microscopy (critical-point-dried tissue; vascular corrosion casts). Prior to casting animals were rinsed using different perfusion pressures. Casting was done by manual injection of the resin, whereby different influx-rates were applied resulting in low, medium and high pressure preparations. We discern 3 phases of tumor angiogenesis (TA) occurring during 4 stages of TG among which vasodilation establishes the first reaction of the host vascular system to a growing tumor implant. During this stage 1 of TG, tumor nidation, nearby sinusoidal dilated host capillaries form globular outgrowings (phase 1 of TA). Subsequently radially arranged sprouts, which preferentially arise from venous host vessels, grow into the centre of the implant (phase 2 of TA). Stage 2 of TG, early tumor growth, is characterized by necrosis of the central tumor tissue and the development of a central avascular cavity. Thus the tumor vascular system is organized like a hollow sphere with a central cavity and a peripheral vascular "envelope" with large vessels embracing the tumor and centrifugally growing vascular sprouts, which arise from the venous part of the vascular "envelope" and invade the surrounding host tissue (phase 3 of TA). During stage 3 of TG, late tumor growth, many vessels of the basket-like vascular "envelope" obliterate. In stage 4 of TG, prefinal phase, the peripheral vascular density decreases continuously. Thus vascular sprouting and proliferation of viable tumor cells is confined to basal regions of the tumor.
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PMID:The angioarchitecture of the Lewis lung carcinoma in laboratory mice (a light microscopic and scanning electron microscopic study). 379 95

Walker ascites tumor cells and an extract derived from such cells (tumor angiogenesis factor, TAF) were injected into the subcutaneous tissue of rats by using a dorsal air sac technique. At intervals thereafter, thymidine-(3)H was injected into the air sac and the tissues were examined by autoradiography and electron microscopy. Autoradiographs of 1micro thick Epon sections showed thymidine-(3)H labeling in endothelial cells of small vessels 1-3 mm from the site of implantation, as early as 6-8 hr after exposure to live tumor cells At this time interval endothelial cells appeared histologically normal. DNA synthesis by endothelium subsequently increased and within 48 hr new blood vessel formation was detected. The presence of thymidine-(3)H-labeled endothelial nuclei, endothelial mitoses, and regenerating-type endothelium was confirmed by electron microscopy. TAF also induced neovascularization and endothelial cell DNA synthesis after 48 hr. A similar response was not evoked in saline controls. Formic acid, which elicited a more intense inflammatory response, was associated with less endothelial labeling and neovascularization at the times studied. Pericytes and other connective tissue cells were also stimulated by live tumor cells and TAF. The mechanism of new blood vessel formation induced by tumors is still unknown but our findings argue against cytoplasmic contact or nonspecific inflammation as prerequisites for tumor angiogenesis.
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PMID:Tumor angiogenesis. Rapid induction of endothelial mitoses demonstrated by autoradiography. 504 Aug 65

Hepatic dearterialization was performed on four patients in an attempt to provide symptomatic relief from metastic carcinoma in the liver. Interruption of hepatic arterial blood supply causes necrosis in larger metastatic tumor deposits, but very small nodules are unaffected by the procedure; this observation supports experimental studies on tumor angiogenesis factor. Interruption of hepatic arterial blood supply results in nonspecific ischemic changes to the hepatic parenchyma, which responds with small nests of regenerating liver cells. This finding appears to support the work of Plengvanit on revascularization of the liver after hepatic artery ligation.
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PMID:Histologic changes seen in the hepatic parenchyma and in metastatic nodules following hepatic dearterialization. 617 41

Tumor-induced capillaries are different from normals in structure and function. In this paper, we reviewed the structure and microcirculation of tumor-induced capillaries and tumor angiogenesis to contribute the development of cancer therapy.
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PMID:[Tumor angiogenesis and cancer therapy]. 619 85

During the past decade a number of pioneering knowledge of neovascularization induced by neoplasm have been accumulated and a clinical application of anti-angiogenesis treatment seems to be launched within very near future. While the most Japanese research workers in the medical field are still dreaming of immunological approaches to cancers. But now we should stand on the wide view of basic biology of cancer and open searches for newer attacking targets of cancers. Such a newer modality may be included in biological treatment against not only tumor growth but also invasion, angiogenesis, and metastasis. As an example of a search for newer attacking target of cancer, here I proposed a view point regarding tumor angiogenesis as a symbiotic system of tumor cells and endothelial cells and I reviewed briefly on recent aspects of angiogenesis and anti-angiogenesis, introducing works of Drs. Folkman, Fenselau, Kumar, Weiss, Rifkin, Langer, Eisenstein, Gullino, and others. I hope this short review may attract many more research workers to the "virgin" field of angiogenesis.
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PMID:[Anti-angiogenesis, a possible new modality of cancer treatment]. 619 87

Study of 14 human infiltrating breast carcinomas revealed new features that shed light on the pathogenesis of tumor stroma formation and on host immunologic defense mechanisms. Fibrin deposits were observed in the stroma of all tumors, particularly at their growing edge. Fibrin may have contributed both to tumor angiogenesis and, with organization, to the formation of the fibrous stroma characteristic of these and other scirrhous carcinomas. We previously proposed similar mechanisms for several animal tumors. All breast carcinomas studied elicited some degree of lymphocytic response at the tumor periphery; lymphocytes penetrated the fibrous tumor stroma poorly, did not exit in significant numbers from central tumor vessels, and, even when greatly outnumbering tumor cells locally, appeared relatively ineffective at tumor cell killing. Microvascular endothelial cell damage was frequently observed and may have been responsible for zones of tumor infarction. Similar observations have been made in skin allografts and animal tumors where rejection was effected principally by microvascular damage and subsequent tissue infarction, not by lymphocyte contact with individual epithelial target cells.
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PMID:Human breast carcinoma: fibrin deposits and desmoplasia. Inflammatory cell type and distribution. Microvasculature and infarction. 626 43

The study of human endothelial cells in tissue culture has been previously limited to umbilical vein, a large vessel source, and microvascular endothelium from human foreskin, spleen, and adrenal. Microvascular endothelium cultured from these sources have required matrix-coated culture flasks, tumor-conditioned medium, or 50% human serum for growth and subcultivation. To obtain cultures of microvascular endothelium with less stringent growth requirements, human adipose tissue was digested with collagenase and endothelial cells were separated from other stromal elements by sequential filtration and layering cells onto 5% albumin. Using standard medium containing 10% fetal calf serum, these cells grew readily to confluence and survived serial passages. When the cultures were subconfluent, cytoplasmic extensions and a capillary-like morphology were observed. Confluent cultures displayed the "cobblestone" appearance characteristic of other endothelial preparations. Electron microscopy demonstrated the presence of characteristic tight junctions and pinocytotic vesicles. Immunofluorescent staining for Factor VIII was positive, and cultures contained angiotensin-converting enzyme activity. Thus, cultures of human microvascular endothelium were readily obtained from adipose tissue and required only standard medium with 10% serum for growth and subcultivation. This system can be used to study human endothelial cell biology and may prove useful in the study of pathologic states such as diabetic microvasculopathy and tumor angiogenesis.
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PMID:Isolation and culture of microvascular endothelium from human adipose tissue. 630 56

In the preceding sections we have shown evidence that growth-promoting factors are involved in three basic situations. In normal embryonic development and function of mature organisms, growth factors such as NGF and EGF are of prime importance in supporting the necessary embryonic cell proliferation and the development of specific cell types. Other factors operate on subsets of mature cells during specialized functions such as inflammation. Included in this set would be factors such as CSF/MGF and Interleukin-2. Another basic function of growth factors has been shown to be wound repair and organ regeneration. This includes the well characterized PDGF and FGF as well as the various renotropic factors and liver growth factors. As these factors must operate in mature organisms with many different cell types and similar cell types in many locations, more specificity is needed than in embryonic growth. This has resulted in the organ specific factors such as the renotropins and in the unique delivery system of the PDGF. The recent discovery and characterization of the transforming growth factors has provided a possible connection between embryonic and normal developmental growth and the rapid cellular proliferation characteristic of tumor cells. The TGF not only interacts with receptors for normal growth factors such as EGF but are also detectable in low levels in normal tissue and embryos. The exact relationships between these various factors will have to await the determinations of more amino acid sequences for comparisons. The other tumor-related product, tumor angiogenesis factor, is also found in normal tissue and inflammatory reaction sites.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Role of polypeptide growth factors in normal and abnormal growth. 640 May 65

Effective study of the malignant phenotype at the tissue level requires model systems that are intelligible both to cell biologists and to pathologists, and that also observe the spatial imperatives intrinsic to tissues in nature. Malignant cells commonly appear in multicellular units, and growth of tumor tissue is seen as an increase in the number of cells and multicellular units. The supporting stroma frequently has an abnormal appearance, and this component of the tissue also increases in mass as the tumor enlarges and spreads. The direction of invasion is influenced by the direction of available metabolites. Histophysiologic gradient culture complies with nature's spatial rationale, since at the substrate-parenchymal interface three functions coincide. These are anchorage, initiation of epithelial renewal, and complete exchange of metabolites. Our model system provides a setting for reconstructing and manipulating many features of the malignant phenotype seen in cancer tissues in nature, such as abnormalities in the sequence of maturation of stratified epithelium, hyperplasias, dysplasias, interaction between different types of epithelium, aggregate formation, tumor angiogenesis, and neoplastic blockade.
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PMID:The propagation of cancer, a process of tissue remodeling. Studies in histophysiologic gradient culture. 656 82

Endothelial cell growth factor(s) from several previously untested human tumor cell lines (i.e., SK-HEP-1, MG63, A375, TE671-C1, RD) were detected using a low cell inoculum growth assay. The final cell density in the 2-cm2 wells was determined by a highly sensitive DNA content measurement performed directly in the tissue culture plates. The sensitivity of the assay to human tumor cell growth factors depended critically on the low cell inocula, 2,000 to 5,000 cells/well. Most of the bovine endothelial cells used were cloned from primary cultures; all the cell lines obtained from various fetal and nonfetal sources responded to the growth factor(s) (up to a 16x stimulation) as well as to endothelial cell growth supplement. Dose response curves showing the cell specific response of bovine endothelial cells were obtained. The growth stimulatory activity and the in vivo chick embryo chorioallantoic membrane assay responses correlated sufficiently to imply that the assay is detecting tumor angiogenesis factor or some closely related activity. This in vitro assay should prove useful in the identification and purification of tumor-derived factors and in the elucidation of the role of these factors in the events comprising angiogenesis.
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PMID:An assay measuring the stimulation of several types of bovine endothelial cells by growth factor(s) derived from cultured human tumor cells. 708 77


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