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

After culturing mouse peritoneal cells in vitro for 4 days, high numbers of cells can be detected that secrete autoantibodies against isologous red blood cells (RBC), modified with the proteolytic enzyme bromelain (Brom). Plaque-forming cell numbers against mouse Brom RBC were significantly reduced by pretreating mouse Brom RBC prior to haemolytic assay with phospholipase C, an enzyme that hydrolyzes phospholipids, notably phosphatidylcholine. In contrast, further treatment of mouse Brom RBC with Brom, neuraminidase, beta-chymotrypsin, trypsin, or papain had no effect on plaque-forming cell numbers. These results show that phosphatidylcholine is an integral part of the mouse RBC autoantigen exposed by Brom treatment.
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PMID:Mouse autoantibodies bind to a phospholipase-C-sensitive structure on red blood cells. 217 39

Information on the secretory behavior of individual parathyroid cells within a cell population has not previously been available. We now report a technique for examining quantitative changes in hormone secretion in individual parathyroid cells. We have used a reverse hemolytic plaque assay to measure cumulative PTH release in single isolated cells. Bovine parathyroid cells were dispersed with trypsin and mixed with staphylococcal protein-A-linked ovine erythrocytes. Cells were plated in a monolayer in the presence of PTH antiserum. After stimulation by an agonist, complement was added to the cells. Lysis of ovine erythrocytes formed a plaque around each individual cell that releases PTH. Results indicate that inhibition of PTH release by calcium was not affected by trypsinization. Plaque formation was dependent on all reagents; serial dilution of antiserum reduces plaque formation. Cells had a markedly uniform secretory response to calcium. We compared PTH release in individual cells measured by the reverse hemolytic plaque assay with hormone release in a parathyroid cell population measured by RIA. There was an inverse relationship between extracellular calcium concentrations and plaque area. Individual cells were more sensitive to calcium (ED50 = 0.4 mM Ca2+) than cell populations (ED50 = 0.8 mM Ca2+). We demonstrate that PTH release can be quantitated in single viable parathyroid cells.
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PMID:Individual parathyroid cells are more sensitive to calcium than a parathyroid cell population. 240 21

Foot-and-mouth disease virus (FMDV) A22 Iraq 24/64 adapted to grow in BHK monolayer cells induced antibodies which neutralized many isolates belonging to the A serotype. Plaque-purified virus isolated from this stock also induced broadly reactive antibodies, showing that this property is not due to the combined response to a mixture of variants in the original stock virus. However, viruses obtained by passage in suspension BHK cells of either the monolayer cell-adapted virus or a virus cloned from this stock resulted in the selection of virus which induced antibodies with highly specific neutralizing activity. In addition to their antigenic properties the monolayer and suspension cell-adapted viruses could be distinguished by plaque morphology, tendency to aggregate and ability to attach to BHK cells. Monoclonal antibodies (MAbs) induced with the plaque-purified monolayer-adapted virus had neutralizing activity almost as broad as polyclonal serum, showing that this property can be represented by a single epitope on the virus. These neutralizing MAbs recognize a trypsin-sensitive epitope on the virus. Surprisingly, sequence analysis of the structural protein-coding regions of the genomic RNAs of monolayer and suspension cell-adapted viruses showed no amino acid differences in VP1, the protein known to contain the major neutralization epitope in FMDV and to be the only protein susceptible to cleavage by trypsin in the virus particle. Although three coding differences were found in the capsid protein these were all located in VP2.
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PMID:Host cell selection of antigenic variants of foot-and-mouth disease virus. 247 82

These activities were measured simultaneously, using synthetic fluorescent protease substrates, in gingival crevicular fluid collected at 6 pre-determined sites from 10 individuals with mild to moderate gingivitis. The three enzyme activities were detected in 85, 18 and 93% of the sites, respectively. The volume of fluid collected from discrete sites was significantly correlated with the total amount of substrate hydrolysed, but not with the specific rate of substrate hydrolysis. Log10 (total trypsin-like activity) was significantly correlated with the Gingival Index, Plaque Index and probing depth (r = 0.319, 0.423 and 0.336), while total glycylprolyl dipeptidase activity was significantly correlated with probing depth (r = 0.381). These findings add to knowledge of the biochemistry of gingival crevicular fluid, but the usefulness of such assays for diagnostic or monitoring purposes in periodontal diseases needs to be determined.
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PMID:Trypsin-like, chymotrypsin-like and glycylprolyl dipeptidase activities in gingival crevicular fluid from human periodontal sites with gingivitis. 269 44

To evaluate the replication of a highly virulent avian influenza A virus in a potential reservoir host, mallard ducks (Anas platyrhynchos) were inoculated with the virulent strain A/Ty/Ont/7732/66 (H5N9). Viruses recovered from the ducks were analyzed by hemagglutination inhibition (HI) and enzyme-linked immunosorbent assay (ELISA) and found to possess antigenically altered viral hemagglutinins. Plaque formation on the Madin-Darby Canine Kidney (MDCK) cell line and on primary chicken embryo cells was investigated, and isolates recovered from the ducks differed from the wild type by being unable to form plaques on MDCK cells without trypsin. This phenotype did not appear to be due to inefficient cleavage of the hemagglutinin by host cell proteases since hemagglutinin immunoprecipitated from cell lysates was cleaved. Although the plaquing phenotype suggested attenuation of the isolates from the ducks, they were not significantly altered in their virulence for chickens shown by infectivity studies in vivo. These results indicate that replication of influenza A/Ty/Ont/7732/66 virus in ducks can produce antigenic and phenotypic variants which are still highly virulent for domestic poultry.
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PMID:Antigenic and phenotypic variants of a virulent avian influenza virus selected during replication in ducks. 281 May 50

Three different methods, namely plaque assay, immunofluorescent cell (IFC) count and end-point dilution (TCID50) were evaluated for quantitative infectivity assay of the cell culture adapted UK strain of bovine rotavirus in secondary calf kidney (CK) cells and BGM cell line. Plaque and IFC count techniques were found equally efficient for infectivity titration of bovine rotavirus. Addition of trypsin into maintenance medium enhanced the sensitivity of the TCID50 method. Both CK and BGM cells served as efficient assay cells for infectivity assay of bovine rotavirus by IFC count and TCID50 methods, whereas, for plaque assay, only CK cells were found suitable.
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PMID:Infectivity assay of bovine rotavirus: evaluation of plaque and end-point methods in comparison with immunofluorescent cell assay. 289 73

The Lincoln strain of bovine rotavirus was found to replicate with cytopathic effects in cultures of GBK cells, a stable cell line derived from bovine kidney, when the cultures were maintained in the presence of trypsin. The virus was readily passaged and the infected cells were shown to contain specific viral antigen by indirect immunofluorescent staining. The virus formed plaques in GBK cell monolayers, when trypsin was incorporated in the agar overlay medium. The plaque count increased about twofold when diethylaminoethyl dextran was further included in the overlay medium. Plaque assay in GBK cells was more sensitive than that in MA-104 cells previously reported by Matsuno et al. The specificity of plaques was confirmed by specific inhibition with antiserum against the Lincoln strain.
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PMID:A sensitive plaque assay for bovine rotavirus in cultures of the bovine cell line GBK. 303 67

Two feline coronaviruses were characterized to determine their biological properties in vitro and their antigenic relatedness to a previously recognized feline infectious peritonitis virus and canine coronavirus. The viruses, designated WSU 79-1146 and WSU 79-1683, were shown to have comparable growth curves with the prototype feline infectious peritonitis virus. Treatment of the feline infectious peritonitis virus strains with 0.25% trypsin indicated that they were relatively resistant to proteolytic inactivation when compared with the feline enteric coronavirus strain. This observation may serve as a useful in vitro marker to distinguish closely related members of the feline coronavirus group. Plaque assay results indicated that the feline infectious peritonitis virus strains produced large homogeneous plaques in comparison to the feline enteric coronavirus strain and canine coronavirus, which showed a heterogenous plaque size distribution. No naturally temperature sensitive mutants were detected in either of the feline coronavirus populations. Both of the viruses were antigenically related to feline infectious peritonitis virus and to a lesser extent to canine coronavirus by virus neutralization.
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PMID:Comparative properties of feline coronaviruses in vitro. 303 90

Reverse hemolytic plaque assays were used to compare the responsiveness of cells from different pituitary regions to the modulatory effects of human pancreatic GH-releasing factor (GRF), TRH, and dopamine (DA). Tissues from the peripheral rim (outer zone) and the central region (inner zone) of adenohypophyses from day 10 lactating rats were dispersed with trypsin, and the cells were placed into culture. On the following day, these cells were subjected to GH plaque assays (conducted in the presence or absence of GRF) and PRL plaque assays (performed with or without TRH and DA). Cells from both zones responded similarly to GRF with a rapid acceleration of GH plaque formation. However, the rate of PRL plaque formation in response to TRH and DA differed between cells from these regions. For outer zone cells, plaque development increased greatly with TRH treatment, but was only moderately affected by DA. Plaque formation from inner zone cells was influenced slightly by TRH, but markedly inhibited by DA. These results suggest that PRL, but not GH, cells from these pituitary regions are differentially responsive to at least two hypothalamic secretagogues. We then performed fixed sequential plaque assays to determine whether the proportions of cells that released PRL only (classical mammotropes) or those that released both GH and PRL (mammosomatotropes) also differed between the inner and outer zones. Using this approach, we found that the outer zone contained a much larger proportion of dual hormone secretors than did the inner zone. These results, when taken together with the responsiveness differences discussed above, raise the possibility that the release of PRL from mammotropes and mammosomatotropes is regulated differently and that the ratio of these two cell types may dictate, in part, the manner in which a specific region of the pituitary responds to hypothalamic input.
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PMID:Functional variations among prolactin cells from different pituitary regions. 310 Feb 86

Plaque-forming activity and T-antigen-synthesizing activity in the crude preparation of simian virus 40 (SV40) decreased to 1/20-27 after treatment with 0.5% sodium deoxycholate (DOC) for 30 min at 37 degrees C. A full restoration of the activity occurred after incubation of DOC-treated virions with the extract of monkey CV-1 cells, host cells for productive infection with SV40. Analysis by sedimentation through 15% sucrose to CsCl cushion (rho = 1.327 g/cm3) revealed that virions in the [35S]methionine-labeled crude virus preparation sedimented to the interface between CsCl and sucrose, and that treatment with DOC resulted in the loss of infectivity and the appearance of virions sedimentable into CsCl cushion. The [35S]methionine-labeled purified virions (prepared after treatment with DOC and sedimentable into CsCl cushion) sedimented to the CsCl-sucrose interface after incubation with the cell extract, with restoration of infectivity. The infectivity-restoring activity of the cell extract was sensitive to ethyl ether, partially sensitive to heating at 75 degrees-97 degrees for 30 min, but resistant to treatment with DNase (50 micrograms/ml), RNase (40 micrograms/ml), or trypsin (0.05%) for 30 min at 37 degrees. These results suggest that lipid-related cellular components bind stably to virions of SV40 and facilitate an efficient infection.
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PMID:Decline in infectivity of simian virus 40 by sodium deoxycholate and its restoration with the extract of monkey kidney cells. 609 25


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