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Biomedical subjects

H Blobel

Publications and source records attributed to H Blobel.

At least 73 records · Page 4Linked to original sources
PubMed1985

Interactions of plasma proteins with group A, B, C and G streptococci.

Streptococci of serological groups A, B, C and G displayed different binding activities for plasma proteins. Most of the streptococci studied, except those of group B, bound immunoglobulin G. All streptococci reacted with fibrinogen and, except those of group B, with fibronectin. The majority of streptococci, but none of group B, had an affinity for alpha 2-macroglobulin. Albumin was bound by all cultures of group G and a few of group C. Haptoglobulin interacted with only 1 group A culture. None of the streptococci bound transferrin. The specificity of binding sites for 125I-labelled plasma proteins was revealed in a series of inhibition experiments with the unlabelled proteins. The binding sites on streptococci of group G showed different sensitivities to trypsin and pepsin. Reactivities for immunoglobulin G, however, remained unaffected after treatments of the streptococci with trypsin. Exposure to heat (30 min, 80 degrees C) partially inactivated binding activities for the plasma proteins. Sodium dodecyl-sulphate and acetylimidazole strongly reduced binding of albumin and to a lesser extent that of alpha 2-macroglobulin. They had no or little effect on the interaction with the other plasma proteins. Dioxane decreased almost all binding activities. Ethanol partially diminished the binding of immunoglobulin G, fibrinogen, fibronectin and alpha 2-macroglobulin. Treatments of group G streptococci with guanidine, urea, formamide or methanol-HC1 did not affect their plasma protein binding activities.

Animals↗
PubMed1985

Inhibition of staphylococcal alpha-hemolysis by monoclonal antibodies against oligomer 12 S alpha-toxin.

Oligomer 12 S alpha-toxin as well as 3 S alpha-toxoid of Staphylococcus aureus induced the formation of monoclonal antibodies (mabs). Mabs against the 12 S alpha-toxin could be demonstrated in 31 and those against 3 S alpha-toxoid in 18 of 120 hybrid cell colonies. Each of these mab-preparations reacted with 12 S, 3 S alpha-toxin and 3 S alpha-toxoid. The reactions were more pronounced with the homologous than the heterologous toxin preparations. Mabs against 12 S alpha-toxin inhibited the hemolytic effects of native 3 S alpha-toxin as well or better than the respective polyclonal antisera.

Animals↗
PubMed1985

Interactions of immunoglobulin G, fibrinogen and fibronectin with Staphylococcus hyicus and Staphylococcus intermedius.

Binding of immunoglobulin G, fibrinogen and fibronectin to 112 cultures of coagulase-positive staphylococci together with 7 of coagulase-negative S. hyicus subsp. chromogenes were investigated. Of the coagulase-positive staphylococcal cultures 45 were S. hyicus subsp. hyicus, 51 S. intermedius and 16 S. aureus. All 45 S. hyicus subsp. hyicus cultures coagulated plasma preparations from pigs and not always those from sheep, rabbits and dogs. Labelled IgG was bound by all cultures of S. hyicus subsp. hyicus and S. aureus, but only by 6 of 51 S. intermedius cultures. Fibrinogen interacted with 28 of the 45 S. hyicus subsp. hyicus cultures, with 17 of the 51 S. intermedius cultures and with S. aureus throughout. Fibronectin reacted with 19 cultures of S. hyicus subsp. hyicus, 11 of S. intermedius and all S. aureus. The binding activities for labelled IgG were more pronounced than those for fibrinogen and fibronectin. None of the 7 cultures of S. hyicus subsp. chromogenes bound any of these plasma proteins. Bindings of fibrinogen and fibronectin to S. hyicus subsp. hyicus and S. intermedius elicited only in part distinct clumping reactions of the staphylococci in the respective plasma proteins.

Animals↗
PubMed1985

Fibrinogen binding inhibits the fixation of the third component of human complement on surface of groups A, B, C, and G streptococci.

Effects of fibrinogen binding to M protein-positive and -negative streptococci on fixation of the third component of human complement (C3) were determined. In all test cultures of serological groups A, B, C, and G fixation of C3 was observed in normal human serum as revealed by quantitative fluorescent immunoassay. Fibrinogen binding inhibited the fixation of C3 on streptococci. The degree of inhibition was proportional to the extent of fibrinogen binding. Thus, inhibition of C3 fixation was most pronounced in strongly fibrinogen-positive streptococci of groups A, C, and G and not demonstrable in fibrinogen-negative cultures of groups C and G. Trypsinization of the streptococci destroyed their capacity to bind fibrinogen and consequently the inhibitory effects on C3 fixation. The carboxymethylated alpha and beta chains of fibrinogen moderately inhibited C3 fixation whereas gamma chain had no influence. These studies may indicate that fibrinogen binding structures other than M protein could also be involved in streptococcal pathogenicity.

Binding Sites↗
PubMed1985

Binding of alpha 2-macroglobulin and haptoglobin to Actinomyces pyogenes.

All 25 cultures of Actinomyces pyogenes tested in the present study bound 125I-labelled human alpha 2-macroglobulin with a mean binding of 65.6%. Thirteen cultures also bound 125I-labelled human haptoglobin with a mean of 51.5%. None interacted with fibrinogen, fibronectin, immunoglobulin G, or albumin. Twenty-eight cultures representing other species of actinomycetaceae did not show any interaction with alpha 2-macroglobulin, haptoglobin, and other plasma proteins tested. The binding of alpha 2-macroglobulin and haptoglobin to A. pyogenes was saturable and could be completely inhibited by the respective unlabelled plasma proteins. The binding of alpha 2-macroglobulin could not be inhibited by unlabelled haptoglobin. On the other hand, alpha 2-macroglobulin blocked the binding of haptoglobin, possibly by steric hindrance. Treatment of the bacteria with trypsin reduced their binding activities for alpha 2-macroglobulin and haptoglobin indicating the protein nature of the binding sites. Exposure to heat (1 h, 80 degrees C) significantly diminished the binding activity for haptoglobin, but not that for alpha 2-macroglobulin. The binding of alpha 2-macroglobulin and haptoglobin could be an important feature in the classification of A. pyogenes among the members of actinomycetaceae.

Actinomyces↗
PubMed1984

Guanidine extraction enhances the binding of human fibrinogen to group-B streptococci.

Treatment of group-B streptococci with guanidine chloride significantly enhanced their capacity to bind 125I-labelled fibrinogen. The increase in binding activity was almost proportional in the range of 0.05 M to 6 M guanidine chloride. Repeated extractions with guanidine chloride further increased the capacity of B streptococci to bind the labelled fibrinogen. On the other hand, urea, even at concentrations up to 8 M, did not alter the fibrinogen binding. The enhancement was most pronounced with B streptococci of serotypes III and III-R. Cultivation of these streptococci in Baker and Kasper medium, which is known to stimulate formation of microcapsules, reduced 125I-fibrinogen binding. Subsequent treatment with guanidine increased their binding activity, presumably by facilitating the accessibility of the binding sites.

Binding Sites↗
PubMed1984

Characterization of immunoglobulin G binding to Staphylococcus aureus strain Wood 46.

Protein A (PA)-activity was detected in Staphylococcus aureus strain Wood 46 which had been considered to be PA-negative. This staphylococcal strain bound 28% of 125I-labelled IgG, compared with 89% by strain Cowan I. The binding activities of both S. aureus strains were saturable, time-dependent and specific. The dissociation constants of 1.6 X 10(-9) M for Wood 46 and 9.3 X 10(-8) M for Cowan I indicated a similar affinity for human IgG in both strains. The number of IgG-binding sites were estimated to be 16,970 for Wood 46 and 41,200 for Cowan I. Exposure to heat and ultrasonication reduced PA-activities of strain Cowan I, but not that of strain Wood 46. Extraction of the staphylococci with guanidine and formic acid resulted in a reduction of IgG-binding activities only in strain Wood 46. Photooxidation, trypsinization and lysozyme treatment also diminished IgG-binding of strain Wood 46 to a larger extent than that of strain Cowan I. Extracellular PA from S. aureus strains Wood 46 and Cowan I could be purified by affinity chromatography on IgG-sepharose. The purified PA preparations gave single protein bands upon SDS-polyacrylamide gel electrophoresis. Their molecular weights were 42,000 and their isoelectric points approximated 5.0.

Binding Sites, Antibody↗
PubMed1984

Early recognition of the CAMP-reactivity in group B streptococci.

Early detection of the CAMP-reactivity of group B streptococci was achieved in 5% sheep or bovine blood agar supplemented with maltose or glucose at a final concentration of 0.04% under aerobic as well as under microaerobic conditions in a candle jar. All 55 cultures of group B streptococci tested on these media yielded distinct CAMP-reactions within 8 to 10 h of incubation at 37 degrees C, allowing a more rapid recognition of these streptococci.

Agar↗
PubMed1984

Colony-formation of staphylococci in fibronectin-soft-agar.

Colony-formation of 50 staphylococcal cultures was examined in fibronectin-, fibrinogen- and serum-soft-agar and compared with the respective fibronectin- and fibrinogen-clumping-reactions. Forty-two of the 50 cultures formed compact colonies in fibronectin-soft-agar undistinguishable from those in fibrinogen- or serum-soft-agar and gave distinct clumping-reactions with fibronectin and fibrinogen. The remaining 8 cultures (7 Staphylococcus aureus and 1 Staphylococcus epidermidis ATCC 14990) grew diffusely and gave no clumping-reactions with fibronectin or fibrinogen. Thus, fibronectin could elicit compact colony-formation of the staphylococci.

Agar↗
PubMed1983

Absorption of human alpha 2-macroglobulin with selected strains of streptococci.

A new interaction was observed between human alpha 2-macroglobulin (alpha 2M) and selected strains of streptococci. The streptococci bound alpha 2M. After its elution from the bacteria, alpha 2M was demonstrated by immunoelectrophoresis against anti-human alpha 2M. The binding of alpha 2M to one streptococcal strain of serological group C and two of group G was confirmed by radial immunodiffusion. Treating the streptococci with trypsin reduced their reactivity with alpha 2M. On the other hand, prolonged treatment with 6 M guanidine-HCl had no effect on the alpha 2M binding. Binding sites for alpha 2M were most likely protein structures on the streptococcal surface.

Absorption↗
PubMed1983

Binding of human fibrinogen and its polypeptide chains to group B streptococci.

Of 51 group-B streptococcal cultures, 20 bound 125I-labelled human fibrinogen. In contrast to the streptococci of groups A, C and G, the group-B streptococci interacted more with the alpha, beta-chain of fibrinogen than with whole fibrinogen. None of the streptococcal cultures reacted with gamma-chain. The fibrinogen-negative group-B streptococci still bound the alpha, beta-chain. The binding of 125I-labelled, alpha, beta-chain could be inhibited by unlabelled fibrinogen with fibrinogen-positive, but not with fibrinogen-negative streptococci of group B.

Alkylation↗
PubMed1983

Variations in the binding of mammalian fibrinogens to streptococci of different animal origin.

Binding of 125I-labelled fibrinogen from humans, bovines, equines, canines and ovines by streptococci of serological groups A, B, C and G was determined quantitatively. All 59 randomly selected streptococcal cultures generally bound more human fibrinogen than the other fibrinogens. Only Sc. dysgalactiae had a higher affinity for bovine fibrinogen. In addition, Sc. dysgalactiae bound distinctly more equine, canine and ovine fibrinogen than the other streptococci. Some cultures of Sc. equi and Sc. zooepidemicus had high binding activities for equine fibrinogen. Low binding capacities were exhibited by B-streptococci, particularly with fibrinogens from horses and dogs.

Animals↗
PubMed1983

Characterization of binding of human alpha 2-macroglobulin to group G streptococci.

An interaction was observed between human alpha 2-macroglobulin (alpha 2M) and streptococci belonging to group A, C, and G. Of 27 group C and 19 group G streptococcal cultures, 13 and 14, respectively, bound 125I-labeled alpha 2M. Some group A streptococci also interacted with alpha 2M. A number of other bacterial species tested did not react with alpha 2M. The binding of 125I-labeled alpha 2M to group G streptococci was time dependent, saturable, and could be inhibited by unlabeled alpha 2M. Inhibition experiments indicated that the streptococcal binding site for alpha 2M differed from the receptors for immunoglobulin G, fibrinogen, aggregated beta 2-microglobulin, albumin, and fibronectin. The alpha 2M binding activity was remarkably sensitive to trypsin and heat treatment indicating its protein nature. Kinetic analysis indicated a homogenous population of binding sites. The number of binding sites per bacterial cell was estimated to be approximately 20,000.

Binding Sites↗
PubMed1983

Purification and properties of a receptor for the Fc-component of immunoglobulin G from Streptococcus dysgalactiae.

A receptor for the Fc-component (FcR) of immunoglobulin (Ig) G was isolated from the cell-free supernatant of a Streptococcus dysgalactiae-culture by affinity chromatography on human IgG-sepharose. The single-step procedure yielded purified FcR with a specific activity of 1.1 x 10(6) U/mg protein. It had an estimated molecular weight of 78 000 dalton and an isoelectric point between pH 4.0 and 4.5. It was destroyed by pronase E and was sensitive to trypsin. Purified FcR gave strong single precipitin lines in the double immunodiffusion test with sera from human, horses, cattle, pigs, sheep, rabbits and guinea pigs. It also reacted with human IgG subgroup 3, differing from protein A of Staphylococcus aureus.

Chromatography, Affinity↗
PubMed1982

[Influence of the coagulase reaction on the leukotactic effect of Staphylococcus aureus in artificial body cavities of rabbits].

It was attempted, to determine the influence of coagulase-induced coagula on the leukotactic effects of Staphylococcus aureus in experimental subcutaneous body-cavities (KK) of rabbits. Purified staphylococcal coagulase mediated a partial coagulation in the KK when fibrinogen had been added. The coagula delayed the leukotaxis into the KK after the injection of (killed) encapsulated and non-encapsulated S. aureus extracted with 6 M guanidiniumchloride (Fig. 1), as well as after the injection of the untreated (viable) staphylococci (Fig. 2). The coagula also delayed phagocytosis, at least during the first hours of the experiments (Fig. 3).

Animals↗