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

Mammary tumor cell growth factor(s) has been identified in extracts of platelets from both male and female rats, as well as in extracts prepared from pooled outdated human platelets. When assayed by the growth promotion of MTW9/PL rat mammary tumor cells in culture, platelet extracts alone were able to support growth 50--75% as well as whole serum. The mitogenic activity from crude human platelet lysates was shown to be trypsin sensitive, relatively stable to extremes of pH, labile to heat treatment at 70 degrees, non-dialysable, ammonium sulfate precipitable, not removed by 56 degrees charcoal treatment, and of apparent molecular weight of 30,000 to 50,000 daltons as estimated by G-100 Sephadex chromatography. The platelet derived mammary growth factor activity was not replaced or potentiated by thrombin or known hormones and growth factors such as prolactin, insulin, 17-beta-estradiol, progesterone, hydrocortisone, L-thyroxine, and mouse epidermal growth factor. The experimental report demonstrates that platelets are a rich source growth factor activity for rat epithelial mammary tumor cells, and that the activity appears to be a polypeptide(s) different from other mitogenic activities known to influence growth of mammary tissue.
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PMID:Platelet derived growth factor(s) for a hormone-responsive rat mammary tumor cell line. 3 Jul 82

Various conditions affecting the release of heat-labile enterotoxin (LT) by enterotoxigenic Escherichia coli have been examined. The pH of a defined medium containing three amino acids, M-9 salts, and 0.5% glucose decreased to less than 7.0 in early log phase of growth, and no extracellular LT was detected. Adjustment of the pH at 8 h from 6.0 to 8.0 resulted in a concomitant increase in LT activity in culture supernatants. The release of cell-associated LT was significantly reduced by preincubation with protease inhibitors and increased by preincubation with trypsin. Cell-associated LT was not released by pH adjustment of cells grown at 21 degrees C; however, polymyxin B treatment released a toxin species active in only the pigeon erythrocyte lysate (PEL) assay system. As the growth temperature was increased, polymyxin B released toxin species which exhibited both PEL and Y-1 adrenal tumor cell activity. Polymyxin B extracts of enterotoxigenic E. coli in early log phase grown at 37 degrees C possessed only PEL activity, whereas extracts from cells in late-log and stationary phases had biological activity in both assay systems. Also, LT released by pH adjustment from mid-log to stationary phase was active in both PEL and Y-1 adrenal tumor cell assays. Gel electrophoresis of polymyxin B extracts revealed at least three molecular weight species active in either the PEL (22,000 daltons and 30,000 daltons) or both the PEL and the Y-1 adrenal tumor cell assay (72,000 daltons), depending on the growth temperature. These observations may help to explain the chemical and biological heterogeneity of most LT preparations and facilitate purification of LT by increasing the yield of enterotoxin.
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PMID:Factors affecting release of heat-labile enterotoxin by enterotoxigenic Escherichia coli. 3 62

Heat-labile enterotoxin (LT) produced by a human strain of enterotoxigenic Escherichia coli (286C(2)) was purified to homogeneity from pH extracts of fermentor-grown cells by ultrafiltration, (NH(4))(2)SO(4) fractionation, hydrophobic chromatography on norleucine-Sepharose 4B, hydroxylapatite chromatography, and Bio-Gel P-150 filtration. Purified LT preparations exhibited biological activity comparable to that of cholera toxin in four bioassays specific for the two enterotoxins (Y-1 adrenal tumor cells, Chinese hamster ovary cells, pigeon erythrocyte lysates, and skin permeability test). The overall yield of LT protein was 20%, which represented a 500-fold purification over pH extracts. A native molecular weight of 73,000 was determined by gel electrophoresis. The toxin dissociated upon treatment with sodium dodecyl sulfate, pH 7.0, into two components with molecular weights of 44,000 and 30,000. Purified LT preparations were remarkably stable over a wide range of storage conditions, temperatures, and pH's. The biological activity was increased by incubation with trypsin and completely destroyed by pronase and proteinase K, whereas deoxyribonuclease I, ribonuclease, and phospholipase D had no effect. The amino acid composition of purified LT was quite different from that of cholera toxin. Neither carbohydrate nor lipopolysaccharide was present in purified preparations. The purification scheme appeared applicable to LT produced by other human and porcine enterotoxigenic strains, but reflected the amount of LT produced by each strain. These data show that LT and cholera toxin share many common chemical and physical properties, but must be purified by different techniques.
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PMID:Purification and chemical characterization of the heat-labile enterotoxin produced by enterotoxigenic Escherichia coli. 3 93

Ascitic fluid samples from 19 patients with ovarian carcinoma, 3 with a benign ovarian tumor, and 5 with cirrhosis of the liver were examined for their content of coagulation factors and components of the fibrinolytic system. The concentration of trypsin inhibitors in the ascitic fluid was significantly higher in the presence of carcinoma. Large amounts of FDP were found in the ascitic fluid in all patients with malignant tumors, but not in the other two groups. Determination of FDP may therefore make it possible to differentiate between malignant and nonmalignant ascitic fluid.
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PMID:Coagulative and fibrinolytic properties of ascitic fluid associated with ovarian tumors. 4 63

Normal peritoneal exudate cells (PEC) were activated as suspension cultures either in mediator-rich supernatants from o-chlorobenzoyl-bovine gamma-globulin (OCB-BGG) stimulated lymphocytes or in antigen-free Sephadex fractions from these supernants. After 24 hr incubation thration. The adherent cell fractions of PEC, recovered by trypsinization from monolayers and activated by this technique, were as cytotoxic as unfractionated PEC. Lymphocyte supernatants and antigen-free fractions of the supernatants induced comparable macrophage-mediated tumor cytotoxicity. Treatment of activated macrophages with trypsin did not alter their cytotoxic capacity.
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PMID:Macrophages activated as suspension cultures with lymphocyte mediators devoid of antigen become cytotoxic for tumor cells. 5 Mar 73

Specific cell-mediated immunity to SV40 tumor-specific transplantation antigen (TSTA) in BALB/c mice undergoing progressive tumorigenesis by syngeneic SV40-transformed cells (VLM) was investigated in vivo using a tumor-cell neutralization test. Specific cellular reactivity to SV40 TSTA was not detected in BALB/c mice bearing large tumors (10-15 mm mean diameter) but was demonstrable after tumor excision. Specific cytotoxic reactivity against syngeneic SV40-transformed cells in vivo could be restored to lymphoid cells from VLM tumor-bearing mice either by culturing the lymphoid cells in vitro or by treating them with papain or trypsin. Enzyme-treated lymphoid cells from MCA tumor-bearing BALB/c mice had no cytotoxic reactivity against VLM cells. These studies suggest that tumor-bearing hosts possess lymphocytes which are sensitized to the TSTA of the tumor but that the reactivity of these lymphocytes is blocked.
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PMID:Restoration of specific immunity against SV40 tumor-specific transplantation antigen to lymphoid cells from tumor-bearing mice. 5 Oct 12

Proteases capable of activating procollagenase from gingiva and from fibroblast and macrophage monolayer cultures were harvested from homogenates of canine tumor mast cells. The mast cell proteases lysed casein and Azocoll but not native collagen. In low salt concentrations the enzymes existed at high molecular weight complexes, which were dissociated by increasing the salt concentration above 1.0 M (NaCl, KCl). Gel filtration in 1.4 M KCl separated the protease activity into three peaks, all of which activated procollagenase. Two of the enzymes showed substrate specificities (hydrolysis of p-tosyl-L-arginine methyl ester and benzoyl-tyrosine ethyl ester) and reactive center reactivities similar to pancreatic trypsin and chymotrypsin. Based on gel filtration, apparent molecular weights of 160 000 (p-tosyl-L-arginine methyl ester esterase), 90 000 (main procollagenase activator) and 36 000 benzoyl-tyrosine ethyl ester esterase) were determined. Activation of procollagenase resulted in a 18-20 000 decrease of the molecular weight. The activation was directly related to the amount of activator added within certain limits. Further addition of activator resulted in proteolytic inactivation of collagenase.
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PMID:Activation of fibroblast procollagenase by mast cell proteases. 5 9

Four cell lines, SK-N-SH, SK-N-MC, SK-N-BE(2), and IMR-32, established in vitro from tumor tissue of patients with neuroblastoma were analyzed by trypsin-Giemsa banding methods. In two of the lines a large, abnormally staining chromosome region was observed. This "homogeneously staining region" (HSR) was considerably longer than any of the bands present in normal human cells and, as revealed by both G- and Q-banding, stained with an intermediate intensity. It was located on chromosomes No 6, 10, 17, or 19 of the SK-N-BE(2) cell line and on chromosome No 1 of the IMR-32 line. In concurrent studies, long HSR's were also observed in Chinese hamster sublines that had been exposed to and had developed high levels of resistance to methotrexate or methasquin and high levels of activity of target enzyme dihydrofolate reductase. For several sublines with the highest levels of enzyme activity, approximately 2% of the total cell protein was dihydrofolate reductase. Of 13 independently derived sublines with acquired resistance to antifolate, only those 7 with greater than 100-fold increases in enzyme activity consistently exhibited HSR's. These regions comprised 2-5% of the total length of the chromosome complement and were specifically localized, as demonstrated by G-banding. Analysis of chromosome replication patterns of the HSR in human neuroblastoma and in drug-resistant Chinese hamster cells by tritiated thymidine radioautography indicated that the long, abnormally staining region replicated relatively rapidly and synchronously and terminated replication before the midpoint of the S phase. The HSR thus appeared to represent a novel chromosome abnormality that may be present in cells with specialized functions. Drug-resistant Chinese hamster cells were characterized by overproduction of target enzyme, whereas human neuroblastoma cells had phenotypes of normal neuronal cells. Whether the HSR is transcriptionally active was not elucidated.
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PMID:A novel chromosome abnormality in human neuroblastoma and antifolate-resistant Chinese hamster cell lives in culture. 6 55

Ovarian carcinoma contains an antigen (TA) which is stable at 100 degrees. Rabbit antisera to glycoprotein-rich extracts of tumors detect TA in 70 per cent of ovarian malignancies, in some benign ovarian cysts, certain normal lung preparations, normal cervix, and squamous-cell carcinoma of the cervix. Highest levels may be associated with mucin secretion. No detectible antigen was present in normal ovary, plasma, A, B, and O erythrocytes, leukocytes, placenta, brain, heart, liver, corpus uteri, spleen, skeletal muscle, or kidney. Prolonged digestion of boiled tumor extracts with papain, trypsin, chymotrypsin, on Sephadex G-150 corresponding to a globular protein of 27,000 to 36,000 molecular weight. A beta-globulin mobility is seen in immunoelectrophoresis. It appears that TA differs in tissue specificity and molecular size from other known ovarian cancer associated antigens.
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PMID:A thermostable antigen associated with ovarian cancer. 6 15

Highly purified vesicular stomatitis virus (VSV) was obtained from VSV-infected SV40-transformed hamster cell lines. Immunization with this virus protected hamsters against challenge with SV40-transformed cells (TSV5-cl2). This protection was obtained regardless of the source of the SV40-transformed cells (e.g. cat, rat, hamster) used to produce VSV, and was therefore associated with the SV40 tumor-specific transplantation antigen (SV40-TSTA). Furthermore, when grown on spontaneously transformed cell lines or on cells transformed by a different oncogenic DNA virus, such as polyoma virus, the VSV failed to protect against the SV40-induced tumor. It was concluded that the SV40-TSTA activity of purified VSV is due to the incorporation of SV40-TSTA within the viral envelope. When VSV was treated with proteolytic enzymes (bromelain, trypsin) no loss of TSTA-induced tumor rejection was observed, although VSV had lost its ability to induce virus-neutralizing antibody. This clearly demonstrates that the TSTA activity is not related to the viral spikes. Phospholipase C suppressed the TSTA activity but neutralizing activity was still detectable in the anti-VSV sera. The results presented here demonstrate that the protection afforded by VSV is highly specific. It is particularly interesting that SV40-TSTA activity may be conveyed by the lipid core of the viral envelope.
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PMID:SV40 tumor rejection induced by vesicular stomatitis virus bearing SV40 tumor-specific transplantation antigen (SV40-TSTA). I. Specificity of immunoprotection and effect of enzyme treatment on TSTA activity. 7 Dec 74


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