Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.10.1 (ERK)
95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Specific and common antibodies to staphylococcal enterotoxins A and E (SEA and SEE) were isolated from anti-SEA and anti-SEE antisera by affinity chromatography. Anti-SEA and anti-SEE antisera were passed through a column with the cross-reacting enterotoxin coupled to a CNBr-activated Sepharose 4B matrix. Specifically bound common antibodies were eluted with NaSCN. The isolated specific antibodies reacted only with the homologous enterotoxin, whereas the common antibodies gave a reaction of identify with both enterotoxins in double gel diffusion plates. The common antibodies had a higher titer against SEE than against SEA. The significance of the isolation of antibodies common to two separate protein molecules is discussed.
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PMID:Isolation of specific and common antibodies to staphylococcal enterotoxins A and E by affinity chromatography. 68 29

Microbial superantigens (SA) activate a significant portion of the T cell repertoire based on their dual avidity for MHC class II antigens and T cell receptor (TCR) epitopes common to products of one or several TCR beta chain variable gene families. While SA that induce massive T cell proliferation and cytokine secretion have been implicated in clinical syndromes characterized by shock and generalized immunosuppression, SA activation of a more restricted T cell response may also have significant, perhaps immunostimulatory, effects on the immune system. To investigate this issue, we measured 3H-thymidine incorporation and polyclonal IgM and IgG secretion by normal human peripheral blood mononuclear cells (PBMC) cultured with a panel of microbial SA, including the Staphylococcus aureus-derived SA, SEA, SEB, SEC-1, SEC-2, SEC-3, SEE, TSST-1, and the Mycoplasma arthritidis-derived SA, MAM. The S. aureus-derived SA induce vigorous proliferation by PBMC, while optimal MAM-induced proliferation is significantly lower in magnitude. In all 12 subjects tested, mitogenic concentrations of MAM reproducibly stimulate unselected PBMC to secrete polyclonal IgM and IgG. In contrast, the S. aureus-derived SA induce Ig production only in cultures containing isolated B cell populations and either very low numbers of untreated autologous T cells, larger numbers of X-irradiated autologous T cells, or very low concentrations of the SA. No difference in the activation of helper (CD4) versus suppressor/cytotoxic (CD8) T cells by MAM and the S. aureus-derived SA was noted. Taken together, these data suggest that MAM's capacity to induce B cell differentiation correlates with its induction of a relatively weak proliferative response by unselected human T cells. MAM-like SA, when encountered in vivo, may result in a significant perturbation of the human immune system and potentially contribute to clinical syndromes characterized by immunostimulation and hypergammaglobulinemia.
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PMID:Human B cell differentiation induced by microbial superantigens: unselected peripheral blood lymphocytes secrete polyclonal immunoglobulin in response to Mycoplasma arthritidis mitogen. 129 44

Superantigens are thought to make external contacts with major histocompatibility complex (MHC) class II molecules and with the V beta portion of a T cell antigen receptor (TCR), thereby stimulating entire families of T cells. The precise mapping of superantigen binding sites on class II molecules may provide valuable information on how TCR and MHC molecules interact. Two bacterial superantigens, staphylococcal enterotoxins A and E (SEA/SEE) bind well to most HLA-DR alleles, but poorly to HLA-DRw53. The sequences responsible for this binding were localized to the putative alpha helix of the DR beta chain by measuring toxin binding to a panel of chimeric class II molecules expressed on transfected cells. Binding of SEA/SEE to the DRw14 (Dw9) molecule suggested that the conserved histidine 81 in the beta chain of most DR molecules was important, whereas the tyrosine 81 in the DRw53 beta chain was detrimental for high-affinity binding. To prove this, reciprocal point mutations were introduced in the DR1 and DRw53 beta chains. Mutation of histidine 81 in the DR1 beta chain to tyrosine reduced SEA/SEE binding, but did not prevent recognition of two DR1-restricted peptides by six of eight antigen-specific T cell lines. Conversely, introduction to histidine at position 81 in the DRw53 beta chain restored normal levels of SEA/SEE binding. These data suggest that a binding site of SEA and SEE lies on the outer face of the beta chain alpha helix, pointing away from the antigen-binding groove.
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PMID:Identification of HLA-DR1 beta chain residues critical for binding staphylococcal enterotoxins A and E. 137 Jun 84

We studied the usefulness of an immunoblot technique for the detection of staphylococcal enterotoxins (SEs) in strains and food extracts. Food samples (milk, yogurt, hot dog sausage, cheese, and mayonnaise) were artificially contaminated with SEA through SEE. Protein A did not interfere with the results; it appeared on electrophoresis gels as bands with molecular weights higher than those of the SEs. Other food proteins were not revealed by the technique. The immunoblot technique proved to be fast, specific, and sensitive for the detection of SEs in foods.
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PMID:Applicability of an immunoblot technique combined with a semiautomated electrophoresis system for detection of staphylococcal enterotoxins in food extracts. 147 49

To compare the oxygen cost of submaximal exercise on the Stairobic stepping (SS) machine with bench stepping (BS), 12 healthy men and women (mean age 23 years) underwent six different five minute exercise bouts that were randomly assigned. Tests were conducted using standard open circuit calorimetry. SS at 40 and 60 st/min was equal to BS at 20 st/min and SS at 80 st/min was equal to BS at 30 st/min for VE and RER. VO2 was equal at 20 st/min (BS) and 60 st/min (SS), and 30 st/min (BS) and 80 st/min (SS). Stairobic MET (SM) displayed values over-estimated actual MET (AM) values at the two lowest SS rates and under-estimated the AM value at the highest SS rate. Forty-eight observations of the MET response of SS were conducted and analyzed (BMDP2R) in a forward stepping solution. The multiple regression equation calculated for AM was: AM = -0.567 + -0.012 (WT) + 0.063 (rate) + 0.612 (SM) with an adjusted R2 of 0.82 and a SEE of 0.90. The physiologic cost of BS was approximately equal to SS at two to three times the BS rate of stepping.
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PMID:Physiologic comparison and validation of Stairobic stepping with bench stepping. 148 21

A staphylococcal enterotoxin visual immunoassay kit (TECRA) has recently become commercially available. Since the kit is an enzyme-linked immunosorbent assay system equipped with polyvalent antisera against staphylococcal enterotoxin types A to E (SEA to SEE) and the test is simple and rapid to perform (4 h), it has been widely used for screening purposes. In this study, the sensitivity of the kit for detection of SEA, SEB, and SEC in ham, cheese, and mushrooms was similar to those of kits based on an enzyme immunoassay and reversed passive latex agglutination: 0.75 to 1.0 ng of SEA per ml, 0.5 to 0.75 ng of SEB per ml, and 1.0 to 1.25 ng of SEC per ml. However, the TECRA kit showed nonspecific reactions with food samples contaminated by microorganisms other than Staphylococcus aureus, such as Enterobacter agglomerans, Enterobacter cloacae, Proteus mirabilis, Pseudomonas aeruginosa, and Serratia marcescens. The substance contributing to the false-positive results differed from true staphylococcal enterotoxins in that it was (i) heat labile (completely inactivated by heating for 2 min at 100 degrees C, whereas true staphylococcal enterotoxins were inactivated by about 10% with this treatment), (ii) lower in molecular weight than staphylococcal enterotoxins, and (iii) not bound to a copper chelate Sepharose gel (all of the substance remained in the unbound wash fraction, whereas staphylococcal enterotoxins were quantitatively bound to the gel). The problem of false-positive results with the TECRA kit could be resolved by heat treatment (2 min at 100 degrees C) or by cleanup procedures involving metal chelate affinity chromatography with copper chelate Sepharose for 4 h before use of the TECRA kit.
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PMID:Nonspecific reactions of a commercial enzyme-linked immunosorbent assay kit (TECRA) for detection of staphylococcal enterotoxins in foods. 151 98

A group of 14 monoclonal antibodies (mAbs) to staphylococcal enterotoxin B (SEB) were obtained by fusion of Sp2/O myeloma cells with spleen cells from female BALB/c mice immunized with commercial SEB. The antibodies belonged to IgG1 and IgG2b subclasses. We evaluated the anti-SEB titres, competition assays and sensitivity of detection by indirect ELISA. Reactivity and cross-reactivity were also studied by indirect ELISA and confirmed by immunoblotting. All the mAbs reacted with SEB and with a second band which had a different electrophoretic mobility and probably represents an aggregate of SEB or SEB bound to membranes. Three mAbs reacted only with SEB and the rest showed cross-reactions with SEC1. No reactions were observed against any other serovar (SEA, SED and SEE) or other proteins.
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PMID:Murine monoclonal antibodies against staphylococcal enterotoxin B: production and characterization. 151 53

Staphylococcal enterotoxins (SE) are potent T-lymphocyte activators that stimulate T cells by directly cross-linking HLA-DR molecules on antigen-presenting cells with the V beta gene products of the T-cell receptor. The different SE activate all T cells expressing a given V beta, and, therefore, have been termed 'superantigens'. Here we show that SE are potent activators of leukaemic B cells from patients with chronic lymphocytic leukaemia (CLL). Purified B cells from seven of eight CLL patients with high WBC counts (greater than 80,000/microliters) responded to one or several of the tested SE (SEA, SEB, SEC1, SED, SEE) by proliferation ([3H]TdR incorporation) and/or Ig secretion. In several instances, the response of leukaemic B cells to SE was much stronger than was the response to other known B-cell activators including EBV, pokeweed mitogen (PWM), phorbolester (TPA), and Staphylococcus aureus Cowan I (SAC). The activation of leukaemic B cells by SE was strictly dependent on the addition of irradiated T cells isolated from healthy donors. FACS analysis of cultured cells ensured that the proliferating cells were indeed B cells. Taken together, these results demonstrate that SE are strong T-cell-dependent B-cell activators that, in some cases, can stimulate maturation of leukaemic B cells which are refractory to other activation signals.
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PMID:B-cell maturation in chronic lymphocytic leukaemia. IV. T-cell-dependent activation of leukaemic B cells by staphylococcal enterotoxin 'superantigens'. 157 90

BB/Wor rats develop spontaneous autoimmune diabetes similar to human insulin-dependent diabetes mellitus. A T-cell-mediated pathogenesis for BB/Wor diabetes is indicated because disease is prevented by neonatal or adult thymectomy and treatment of diabetes-prone rats with monoclonal antibodies directed against CD5 or CD8 T-cell surface markers. Disease can be adoptively transferred with injections of concanavalin A-activated spleen cells from either acutely diabetic or RT6.1 T-cell-depleted diabetes-resistant BB/Wor rats. We used microbial superantigens to stimulate spleen cells from RT6.1 T-cell-depleted diabetes-resistant rats and demonstrated that such cells activated with staphylococcal enterotoxins (SEs) can also transfer diabetes. The diabetogenic effector T cells are readily activated by SEA, SEC3, and SEE, whereas SEB- and SEC2-activated cells are far less effective in the adoptive transfer of diabetes. These results demonstrate that microbial superantigens are capable of activating self-reactive and diabetes-inducing T cells in vitro in the BB/Wor rat. Ubiquitous microorganisms may be the environmental trigger for autoimmunity in susceptible individuals.
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PMID:Staphylococcal enterotoxin-activated spleen cells passively transfer diabetes in BB/Wor rat. 160 77

Human umbilical vascular endothelial cells (HUVEC) express HLA class II molecules upon stimulation with recombinant human interferon-gamma (IFN-gamma). Staphylococcal enterotoxin (SE) A (SEA)-binding assay using [125I]-SEA showed the presence of specific SEA binding in HUVEC stimulated with IFN-gamma but not in unstimulated HUVEC. Levels of HLA class II expression and SEA-binding increased as the IFN-gamma concentration and the period of stimulation were increased. Binding of [125I]-SEA to the IFN-gamma-stimulated HUVEC was reduced markedly by an anti-DR/DP MoAb. T cells produced IL-2 upon stimulation with a group of SEs (SEA, SEB, SEC, SED and SEE) in the presence HUVEC stimulated with IFN-gamma but not in the presence of control HUVEC. The level of accessory cell activity in the IFN-gamma-stimulated HUVEC was related to the level of HLA class II expression and SEA-binding activity. Antibodies to HLA class II molecules almost completely inhibited the response. These results indicate that HLA class II molecules are directly involved in the acquisition of these activities in HUVEC.
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PMID:Involvement of HLA class II molecules in acquisition of staphylococcal enterotoxin A-binding activity and accessory cell activity in activation of human T cells by related toxins in vascular endothelial cells. 173 96


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