Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Methods have been developed which isolate single viable cells from the primary growths of two tumour systems (a lymphosarcoma and a carcinoma) and their secondary deposits. Subsequent comparisons of the surface-membrane structure of pairs of these primary and secondary cells, using lactoperoxidase-catalysed radioiodination coupled with polyacrylamide-gel electrophoresis, suggest that their overall structures are qualitatively very similar. This latter picture is still maintained when the isolated cells are treated with trypsin or incubated in complete medium before radioiodination. Analysis of the incorporated label into defined sections of the electrophoretic patterns revealed small quantitative differences between primary and secondary cells. In particular, slightly reduced incorporation into certain surface components of secondary cell preparations was seen. However, these did not occur for all the animals investigated, and also they did not consistently occur if the isolated cells were incubated in complete medium. The most similar overall change observed for the two tumour systems was a slight reduction in the secondary cells of a 20K mol. wt surface component.
Br J Cancer 1979 Oct
PMID:Surface protein distributions in cells isolated from solid tumours and their metastases. 58 23

In the last 11 years the authors have succeeded in isolating nearly 40 enzyme inhibitors of small molecular size from microbial origins. These inhibitors proved to be not only useful tools in analyses of homeostasis of living organisms but also promising agents for cancer chemotherapy. Leupeptin was originally isolated as an inhibitor against serine or thiol proteases such as trypsin, plasmin, papain and cathepsin B. And soon it was demonstrated that leupeptin suppressed chemical carcinogenesis in rats. Pepstatin has an extremely strong activity to inhibit pepsin and cathepsin D. It also inhibits ascites accumulation caused by neoplastic diseases. Bestatin is a specific inhibitor against aminopeptidase B and leucine aminopeptidase. The enzymes are located on the surface membrane in various kinds of cells including lymphocytes. Bestatin was shown to enhance not only blastogenesis of lymphocytes in vitro but also establishment of delayed-type hypersensitivity in vivo. Combined use of bestatin and other antitumor agents gave promising results in animal experiments. Studies on enzyme inhibitors have provided us a new approach to cancer chemotherapy.
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PMID:Enzyme inhibitors in relation to cancer therapy. 61 3

The expression of growth control and morphological transformation was studied in methylcholanthrene-transformed C3H/10T 1/2 CL8 cells serially propagated in CDM by first exposing cells to albumin (0.1%) before dispersing them with trypsin (50 microgram/ml). In serum-supplemented media, methylcholanthrene-transformed C3H/10T 1/2 CL8 cells exhibit various aspects of the transformed phenotype such as irregular morphology, extensive cell overlap, lack of density-dependent inhibition of division, a saturation density of 1.1 X 10(5) cells/sq cm and tumorigenicity in vivo. Cell phenotype in CDM was dramatically altered. Methylcholanthrene-transformed C3H/10T 1/2 1/2 CL8 cells adapted to CDM exhibited a regular epithelioid morphology with no cell overlap and formed confluent monolayers of nonproliferating cells at a saturation density of 5 X 10(4) cells/sq cm. The mean generation time of logarithmic-phase cells was 25 to 27 hr. Reversion to the transformed phenotype followed addition of albumin (0.1%) or serum (2%) to logarithmic-phase cultures or exposure (30 to 60 sec) to trypsin (10 microgram/ml). Cultures in CDM reexposed to serum remained highly tumorigenic in vivo. The data suggest that absorbed proteins may block transformation-sensitive cell surface sites responsible for growth control and that these sites are inactivated by trypsin.
Cancer Res 1978 Feb
PMID:Restoration of growth control in malignantly transformed mouse fibroblasts grown in a chemically defined medium. 62 Apr 13

Autoradiograms of histologic slides of 58 human cone specimens with dysplasia and carcinoma in situ were analyzed after tissue samples were incubated with labeled RNA precursors. Both the vertical and lateral distributions of labeled cells were rather uniform in the major part of the epithelium, which suggested that the tissue remained metabolically active during incubation. Only the uppermost epithelial cells in heavily labeled areas were devitalized as deduced by the morphologic appearance of the cells, the absence of labeling in the cells, the trypan blue exclusion test, and the trypsin digestion test. The viability of large epithelial areas suggested that the previously reported focal distribution of proliferating and nonproliferating areas in the cervical epithelium is a genuine phenomenon and not the result of focal epithelial devitalization acquired during incubation.
J Natl Cancer Inst 1978 Mar
PMID:Viability of the human cervical epithelium with dysplasia and carcinoma in situ. 62 62

To determine whether temperature levels commonly encountered in hot beverages denatured the DNA of intact human squamous cells, a fluorescent probe and model system with trypsin-treated desquamated buccal cells were employed. The probe statistically distinguished between single- and double-stranded DNA in a population of suspended cells by the differential bond strengths of DNA-acriflavine complexes over a 4--25 degrees C temperature gradient. The fluorescence of complexed dye was quenched and that of freed dye was restored, which simplified analysis. After cell pellets were admixed with small volumes of suspension medium preheated to 70 or 80 degrees C for 6 seconds, quickly cooled, and stained with acriflavine under conditions favoring the intercalative mode of binding, a temperature-dependent increase occurred in the fraction of complexed dye that was released over the 4--25 degrees C test range. This increase suggested that brief heating partially denatured the DNA of human buccal squamous cells.
J Natl Cancer Inst 1978 Jan
PMID:Fluorescent probe study of DNA conformation in briefly heated human squamous cells: brief communication. 62 26

Immunization of rabbits with a human fetal pancreas extract produced precipitating antibody against an antigen present only in fetal pancreas and extracts of human pancreatic carcinoma. Pancreatic oncofetal protein (POP) migrated on immunoelectrophoresis in the alpha1-alpha2 region, thus making possible its detection by counterimmunoelectrophoresis. POP was found in the 12,000 X g supernatant of fetal pancreas and could be precipitated with (NH4)2SO4 at concentrations between 30 and 45%. The antigen was partially purified by consecutive centrifugation at 12,000 X g, 40% (NH4)2SO4 precipitation, and ion-exchange chromatography. Treatment of the POP with trypsin completely abolished its antigenic activity; this suggested that the antigen was a protein or a moiety closely associated with protein.
J Natl Cancer Inst 1978 Jun
PMID:Immunologic studies on a pancreatic oncofetal protein. 65 Jul 7

Enteropeptidase, trypsin, and chymotrypsin activity in basal and secretin-stimulated duodenal juice of 20 normal adult volunteers and 15 patients with gastrotestinal disease were determined. All enzyme concentrations showed skew distributions, but fluctuations in the secretin-stimulated juices were less pronouced than in the basal secretions. Secretin administration had no influence on the release of enteropeptidase from human duodenal mucosa, but resulted in a very small increase in secretion of pancreatic enzymes. Six out of seven patients with chronic alcoholic pancreatitis or cancer of the pancreas exhibited highly significant elevations of enteropeptidase in their basal as well as secretin-stimulated duodenal juice. It is suggested that raised luminal enteropeptidase activity may be the result of pancreatic insufficiency or elevated blood glucagon concentrations.
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PMID:Enteropeptidase levels in duodenal juice of normal subjects and patients with gastrointestinal disease. 66 28

Cell Adhesion Factor, complexed to insoluble collagen-coated tissue culture dishes, is required for the attachment of fibroblasts to this substrate. In solution, the factor has no demonstrable affinity for cells in suspension following trypsin-EDTA removal of cells from monolayer. Cell surface receptors for the factor are present during the assay period since cells allowed to recover for 1 h at 37 degrees C, 4 degrees C or in the presence of 10(-6) M cycloheximide show exactly the same kinetics of adhesion as control cells. It is demonstrated that Cell Adhesion Factor acquires affinity for the cell surface only following its binding to collagen.
Int J Cancer 1978 Jul 15
PMID:Substrate activation of cell adhesion factor as a prerequisite for cell attachment. 68 Oct 24

The cell-surface proteins of 6 different melanoma cell cultures have been labelled with 125I using lactaperoxidase-catalysed iodination. Fractionation of the proteins was achieved using 5--22.5% polacrylamide-gradient gel electrophoresis in the presence of sodium dodecyl sulphate (SDS) and the proteins were detected by autoradiography. Up to 24 labelled proteins were detected in the individual cell cultures, but the proteins labelled differed considerably in the 6 cultures examined. A possible reason for this, involving variation in the glycosylation of cell-surface glycoproteins is discussed. Cells of the same melanoma line had similar cell-surface proteins at different passage levels, but changes in the labelled proteins occurred when the culture conditions were altered. The cell-surface proteins of high molecular weight were cleaved by trypsin, but most of the low mol.-wt. proteins were resistant to trypsin. The "large external transformation sensitive" (LETS) protein detected as a major protein on fibroblasts in culture was not a dominant protein on the melanoma cells. It was detected on only 4/6 cell cultures. Possible relationships of the cell-surface proteins described in this study to morphology, immunological properties and proteolytic activity of human melanoma cells are discussed.
Br J Cancer 1978 Jul
PMID:Lactoperoxidase-catalysed iodination of surface proteins on human melanoma cells. 68 8

Sera from rabbits injected with BCG and then with endotoxin contain a factor (tumour-necrosis factor TNF) which, even at high dilutions, is cytotoxic in vitro for mouse L cells and some other cell lines. Using a 51Cr-release assay, cytotoxicity was detected as early as 7-8 h after addition of TNF serum to L cells and cell death was evident microscopically by 24 h. TNF was cytotoxic at 37 degrees C but not at 21 degrees C or 4 degrees C, and acted on both dividing and non-dividing cells. The antimetabolites sodium azide and dinitrophenol partially protected L cells from TNF, suggesting that actively metabolizing cells are the most sensitive. Treatment of L cells with trypsin did not delay cytotoxicity nor was cytotoxicity inhibited in the presence of various saccharide derivatives of cell-surface glycoproteins. Rabbit TNF was remarkably stable with a mol. wt. of 40-50,000. It was eluted with the more acidic serum proteins on ion-exchange chromatography, but precipitated in 50%-saturated ammonium sulphate. Sensitivity to TNF could not be correlated with tumourigenicity of several animal and human lines tested nor with the production of C-type viruses.
Br J Cancer 1978 Aug
PMID:Tumour-necrosis factor from the rabbit. I. Mode of action, specificity and physicochemical properties. 69 46


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