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Biomedical subjects

G Kronvall

Publications and source records attributed to G Kronvall.

At least 109 records · Page 6Linked to original sources
PubMed1982

Surface receptors for serum albumin in group C and G streptococci show three different types of albumin specificity.

A total of 100 bacterial strains were tested for binding uptake of radiolabeled albumin preparations from 15 mammalian species. Three types of surface structures with specific binding sites for albumin were defined. A previously described receptor for albumin was separated into type a in Streptococcus equisimilis strains and in human group G streptococcal strains and type b in bovine group C streptococci. A new type of albumin receptor, type c, was found in Streptococcus dysgalactiae strains, the only receptor type so far with high affinity for bovine serum albumin. Type of albumin receptor correlated with bacterial species. The three receptor types showed high binding capacities; 2 X 10(8) bacterial organisms bound from 5 to 16 micrograms of albumin. All types of albumin receptors were stable to heat treatment at 80 degrees C for 5 min, but susceptible to both pepsin and trypsin treatment. Bacteria-bound albumin preparations were eluted at various concentrations of KSCN, reflecting differences in affinity. Up to 500 micrograms of human fibrinogen or polyclonal human immunoglobulin G had no inhibitory effect on the uptake of albumin, indicating a separate molecular localization of receptors for these proteins.

Animals↗
PubMed1982

Analysis of a single reference strain for determination of gentamicin regression line constants and inhibition zone diameter breakpoints in quality control of disk diffusion antibiotic susceptibility testing.

An equation was derived from known formulas to express the size of the inhibition zone diameter in the disk diffusion antibiotic susceptibility test as a function of the disk content of antibiotic. The equation permitted a calculation of regression line constants for the correlation between zone diameter and the minimum inhibitory concentration (MIC) with a single reference strain. Analysis of reference strains Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, and Pseudomonas aeruginosa ATCC 27853, as well as 12 clinical isolates belonging to these species, showed a linearity between zone size squared and the logarithm of disk content in tests with 10-, 30-, and 100-micrograms gentamicin disks. All three species, however, gave regression line constants which were characteristic for the individual bacterial species. Calculations of zone diameter breakpoints corresponding to recommended MIC limits with E. coli and P. aeruginosa reference strains gave an accurate prediction of gentamicin susceptibility. Histogram analysis of 48 strains of Streptococcus faecalis from clinical specimens showed a distribution of zone diameter values which would result in false classification of susceptibility with breakpoints calculated for the other bacterial species studied. Single reference strain analysis of S. faecalis ATCC 29212 (gentamicin MIC, 8 micrograms/ml) permitted the calculation of breakpoints which accurately assigned the strains tested to the intermediate category of susceptibility. Single reference strain analysis offers a quality control method for individual laboratories that allows the determination of inhibition zone diameter breakpoints corresponding to recommended MIC limits with no MIC determinations required.

Bacteria↗
PubMed1982

Staphylococcus aureus antibodies in patients with staphylococcal septicemia. Comparisons between solid-phase radioimmunoassay and crossed immunoelectrophoresis.

Antibody responses against teichoic acids and other antigens from Staphylococcus aureus in 23 patients with septicemia and 8 patients with endocarditis caused by S. aureus were investigated. Both methods used--solid-phase radioimmunoassay (SPRIA) and crossed immunoelectrophoresis (CIE)--detected significantly higher titres in the endocarditis group. The SPRIA method utilized a sonicated extract of S. aureus, strain Wood 46 for the quantitation of antibodies. In CIE precipitating anti-teichoic acid antibodies were measured. There was no absolute correlation between the two assays, indicating that the antibodies measured were directed at partly different antigens. The two tests might be complementary to each other when used in combination.

Antibodies, Bacterial↗
PubMed1981

beta 2-Microglobulin is bound to streptococcal M protein.

The presence of receptors for three human proteins (fibrinogen, IgG, and beta 2-microglobulin (beta 2m)) was studied in group A streptococcal strains. M type 1, 12 and 14, and in M protein-negative variants of these strains. Fibrinogen binding was detected in all six strains. IgG did not bind to the two type-12 strains and uptake was low in both type-14 strains. The type-1, M protein-positive strain was negative in binding experiments with radiolabelled IgG, whereas the M protein-negative variant was strongly positive. Aggregated beta 2m showed a high degree of reactivity with the M protein-positive strains but not with the corresponding M protein-negative variants. The results indicate that the receptor for aggregated beta 2m is located on M protein in group A streptococci.

Bacterial Proteins↗
PubMed1981

Analysis of bacterial cell wall proteins and human serum proteins bound to bacterial cell surfaces.

A method was developed for the characterization of proteins non-covalently bound to the cell wall of Gram-positive cocci. The method employs radioactive labelling of cell wall proteins followed by solubilisation and analysis on polyacrylamide gel electrophoresis in sodium dodecyl sulphate. Using this experimental procedure, protein patterns obtained from group A, C and G streptococcal strains showed marked similarities within each group. Protein peaks were also found to be shared between group C and G strains. Two major peaks with molecular weights of about 30 000 and 70 000 characterized group A strains, whereas group C and G strains showed one consistent peak of about 45 000, thus reflecting the closer relationship between these two groups as compared to group A streptococci. By incubating bacteria with human serum proteins before labelling, solubilisation and electrophoretic analysis, it was also possible to study external proteins specifically bound to the bacterial surface. A group G streptococcus, strain G 148, showed protein peaks corresponding to its known specific binding of human albumin and immunoglobulin G, but also additional protein peaks. When Staphylococcus aureus, strain Cowan I, was pre-incubated with human serum in excess, protein peaks corresponding to heavy and light chains of immunoglobulins were seen. Three more protein peaks of serum origin were also detected, indicating binding of proteins other than Ig to S. aureus. Experiments with protein A-coated Sepharose beads resulted in the same protein pattern, suggesting that binding of these different polypeptides is indeed mediated by protein A.

Bacteria↗
PubMed1981

Binding of fibrinogen degradation products to S. aureus and to beta-hemolytic streptococci group A, C and G.

Binding of fibrinogen degradation products was measured to Gram-positive cocci known to carry receptors for human fibrinogen. Forty-one strains of S. aureus and group A, C and G streptococci were studied. The largest plasmin produced fragment (X-fragment, HMWDP) showed higher binding levels to the bacterial receptors in all four species as compared to intact fibrinogens. The enzymatically produced C-terminal fragment D was strongly reactive, whereas the N-terminal fragment E was non-reactive. Inhibition experiments showed that reactive fragments were bound to the same receptors as fibrinogen. Three chemically-produced and well-characterized fragments from the terminal and the middle portions of the fibrinogen molecule were all negative in binding assays. The binding patterns for fibrinogen and the fragments tested were identical in the four bacterial species tested, S. aureus and group A, C and G streptococci. The results confirm and extend earlier data on similarities between fibrinogen receptors on these Gram-positive bacterial species.

Binding Sites↗
PubMed1981

Receptors for fibrinogen and aggregated beta 2-microglobulin detected in strains of group B streptococci.

Binding of radiolabeled human fibrinogen and aggregated beta-microglobulin was measured in 60 strains of beta-hemolytic group B streptococci. Positive fibrinogen binding was detected in seven of the strains. Six of the group B strains showed an uptake of aggregated beta 2-microglobulin. Four individual strains carried both receptors, indicating a positive correlation between their occurrence. Inhibition studies showed that fibrinogen competed sterically with beta 2-microglobulin binding. Receptors for both proteins were trypsin sensitive. The presence of receptors did not correlate with the serological type of the 49 group B strains tested. However, all seven type II strains were negative. No uptake of fibrinogen was noted in any of 40 group D strains tested. Binding structures for fibrinogen and aggregated beta 2-microglobulin detected in group B streptococci were similar to receptors for the same proteins in group A, C, and G streptococci in terms of mutual correlation and steric interference of binding. The occasional occurrence of these receptors also in group B strains might reflect a common origin of some types of surface proteins in gram-positive cocci.

Beta-Globulins↗
PubMed1981

Immunoglobulin characterization by bacterial absorption of antibrain antibodies in multiple sclerosis.

Complement-fixing (CF) antibrain antibodies are frequently found in serum and CSF in multiple sclerosis (MS). They represent several specificities and appear to be synthesized on both sides of the blood-brain barrier. Five sera and six CSF samples from 11 MS patients, representing 6 different specificities of antibodies, were absorbed with a series of bacterial strains with affinity for various immunoglobulins. Reactivity with brain preparations was eliminated by absorption with the following IgG absorbents: Staphylococcus aureus strain Cowan I, group A streptococcus strain A R1, and group G streptococcus strain G 148, but not by absorption with strains with low or no affinity for IgG. The results indicate in all tested samples the IgG1 and/or IgG2 nature of the antibrain antibodies.

Absorption↗
PubMed1980

New bacterial absorption method for determination of hepatitis A IgM and IgA antibodies.

Antibodies against hepatitis A virus (anti-HAV) can be determined by a commercially available radioimmunoassay (RIA) (HavabTM, Abbott). To discriminate between recent and past hepatitis A infection this RIA was used in combination with absorption with protein A-containing staphylococci. However, nonabsorbable anti-HAV was repeatedly detected in late-convalescent sera using this methods. The nature of these antibodies was studied in serum samples from 12 such patients. In all patients, the late-convalescent sera contained no IgM class anti-HAV as judged by sucrose density gradient centrifugation. The restricted specificity of staphylococcal protein A explains the lack of absorption. Some recently described streptococcal strains capable of binding all IgG subclasses (including IgG3) as well as both IgA subclasses were, therefore, added to the staphylococci. Absorption studies using these strains indicated that the previously nonabsorbable anti-HAV in these 12 patients was mainly of the IgA class. A bacterial mixture including IgA-binding streptococci seems preferable to routine determination of IgM anti-HAV in acute hepatitis A diagnosis. The results also indicate that IgA anti-HAV in serum can persist for more than two years after a hepatitis A infection.

Absorption↗
PubMed1980

Binding of murine myeloma proteins of different Ig classes and subclasses to Fc-reactive surface structures in gram-positive cocci.

Twelve different murine myeloma proteins were tested for binding to seventy Gram-positive strains belonging to group A, C and G streptococci and to Staphylococcus aureus. Group A streptococci, known to bind human IgG, were incapable of binding any of eight murine IgG immunoglobulins tested except for one strain that bound an IgG2b myeloma protein. In contrast, group C and G streptococci interacted with murine immunoglobulins of subclasses IgG2a, IgG2b and IgG3, and G strains also to a lesser extent with IgG1. Bovine and equine-group C streptococci did not differ from human group C streptococci in their IgG reactivity. Staphylococcal strains showed a high reactivity with murine myeloma components of IgG subclasses 2a, 2b and 3 and a low but definite binding of an IgG1 myeloma protein. IgA myeloma protein S-122 interacted with nine of fifteen group A streptococci. This binding could not be inhibited by human IgG and the reactivity is thus different from Fc-mediated binding of immunoglobulins. One of three IgA myeloma proteins tested, TEPC 15, bound to staphylococci. The Fc specificity of this interaction was confirmed by chromatography on protein A-Sepharose and by inhibition studies using polyclonal human IgG. The protein A reactivity of this monoclonal protein was detected in IgA aggregates and absent in the monomeric form of IgA.

Animals↗
PubMed1980

Demonstration of specific binding sites for human serum albumin in group C and G streptococci.

A total of 297 bacterial strains belonging to 27 species was tested for quantitative uptake of radiolabeled human serum albumin. Specific binding sites with high affinity for human serum albumin were found exclusively in group C and G streptococci. The albumin binding was found to be a time-dependent, saturable, and displaceable process which obeyed simple kinetic equations. Scatchard analysis revealed that human serum albumin bound to a homogeneous population of receptors with an affinity in the order ot 10(7) liters/mol and that the average bacterial cell carried more than 80,000 binding sites. The albumin receptor is a heat-stable component susceptible to proteolytic digestion. It has a surface localization separate from the receptors for immunolgobulin G, fibrinogen, aggregated beta 2-microglobulin, and haptoglobin. In individual strains, albumin reactivity was also detected independently of these other types of interactions with human proteins.

Antigens, Bacterial↗
PubMed1980

Demonstration of a new type of immunoglobulin G receptor in Streptococcus zooepidemicus strains.

Forty-seven bacterial strains representing four different group C streptococcal species were tested for binding of human and bovine immunoglobulin G (IgG) subclasses. Specific binding sites for IgG were found in all bacterial species studied. The four species included differed, however, in their capacities to interact with various IgG subclasses, indicating the existence of different types of IgG receptors. Streptococcus equisimilis and Streptococcus dysgalactiae were found to carry the same type of IgG receptor, one that is identical to the previously described Fc-binding structure type III. A new type of bacterial IgG receptor was detected in Streptococcus zooepidemicus strains. This receptor exhibits a protein A-like subclass specificity, with binding of human IgG1, IgG2, and IgG4 and of bovine IgG2. However, differences in their capacities to interact with other non-human immunoglobulins indicated that these two immunoglobulin-reactive structures were different. All types of IgG receptors in group C streptococci were found to be heat stable but susceptible to proteolytic enzymes. The inability of human serum albumin or fibrinogen to inhibit the uptake of radiolabeled IgG shows that the IgG receptor is separate from binding sites for these two other proteins on the bacterial cell surface. The existence of similar IgG receptors in closely related streptococcal species suggests that these structures have a common origin.

Animals↗
PubMed1980

Effect of specific binding of human albumin, fibrinogen, and immunoglobulin G on surface characteristics of bacterial strains as revealed by partition experiments in polymer phase systems.

Four strains of gram-positive cocci with different combinations of positive binding of human proteins were investigated with respect to changes in physicochemical surface properties after specific protein binding. Staphylococcus aureus Cowan I, two group A beta-hemolytic streptococci, and one group G streptococcal strain were studied; they represented three different combinations of reactivity for human serum albumin, human immunoglobulin G, and fibrinogen. Using single-tube partition of bacterial cells in a dextran-polyethylene glycol system of constant polymer concentration but varying ionic compositions, it was possible to detect changes in the partition of bacteria after specific protein binding. There was a correlation between the binding of radiolabled human proteins to the bacterial strains and the effect of human proteins on the partition of the bacteria in the phase systems. Thus, the specific binding of proteins to the bacteria changes their physicochemical surface properties. These types of bacteria-protein interactions may play an important role in modulating host-parasite relationships.

Animals↗
PubMed1980

Further characteristics of beta2-microglobulin binding to oral streptococci.

A total of 85 strains of oral bacteria representing Streptococcus mutans, S. sanguis, S. Mitior, S. salivarious, S. milleri, S. infrequens, S. durans, S. lactis, S. faecalis, S. faecium, S. equinus, Streptococcus species group E, Actinomyces, and one group A Streptococcus were tested for binding of aggregated human beta 2-microglobulin. Positive affinity between bacteria and aggregated human beta 2-microglobulin was detected in 36% of the strains. No apparent correlation with bacterial species, serotype, or group was noted. No positive strains were detected among seven group I:A S. sanguis strains (P < 0.01). Binding constants for one S. mutans strain indicated heterogeneous binding structures on the bacterial surface. The number of binding sites for aggregates of human beta 2-microglobulin involving multipoint attachment varied from 70 to 1,700 per bacterial cell. With whole saliva as buffer, a general increase in affinity was seen. Variations in salt concentrations of the buffers revealed different salt-dependent species-associated uptake patterns. Oral bacteria tended to have an uptake maximum at a salt concentration similar to that seen in saliva. Binding structures for aggregated beta 2-microglobulin on oral streptococci were sensitive to pepsin, heat, and formaldehyde treatment. Bacterial binding structures for aggregated beta 2-microglobulin might represent one of several factors of importance for bacterial attachment in the oral cavity. Experimental conditions reflecting the salivary milieu increased the degree of interaction, emphasizing the importance of physiological test systems for such studies.

Actinomyces↗