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Biomedical subjects

A Forsgren

Publications and source records attributed to A Forsgren.

At least 181 records · Page 10Linked to original sources
PubMed1976

Lymphocyte stimulation by protein A of Staphylococcus aureus.

Protein A from Staphylococcus aureus (SpA) is known to bind to the Fc region of most mammalian IgG classes. In the present article data are presented showing that SpA is a highly efficient mitogen for human peripheral B lymphocytes, with no detectable activity for T lymphocytes. In order to achieve optimal stimulating conditions SpA should be presented to the lymphocytes on an insoluble matrix, such as the SpA-positive bacteria themselves or SpA covalently attached to Sephadex or Sepharose beads. Using such conditions SpA is equivalent with regard to stimulatory capacity for B lymphocytes as phytohemagglutinin is for the human T lymphocytes. Specificity controls proved beyond doubt that SpA and not any other contaminating product is the B cell mitogen. It is concluded that SpA as an inducer of human B lymphocyte division might serve as a highly useful assay in the clinical assessment of B lymphocyte function. It should also be a suitable tool in the fine analysis of B lymphocyte activation via the specific interactions with surface IgG molecules.

B-Lymphocytes↗
PubMed1975

Group B streptococci in venereal disease clinic patients.

The isolation rates of group B streptococci for 457 men and 300 women attending a venereal disease clinic were 16-4 and 20-6% respectively. The frequencies were significantly increased by using a selective medium and by taking specimens from the female urethra as well as the cervix. In contrast to gonorrhoea the presence of group B streptococci could not be related to promiscuity. In addition, the isolation of group B streptococci was found to be independent of a concomitant gonococcal infection. This study indicates that group B streptococci have little relation to the clinical signs and symptoms of genital infection, such as dysuria, discharge and inflammatory mucosal reaction.

Adolescent↗
PubMed1975

Studies of the alternate pathway in chelated serum.

Activation of the alternate pathway in chelated serum by cobra venom factor (Co F), endotoxin of Escherichia coli, inulin, and zymosan was studied by immunoelectroprhoresis, radial immunodiffusion, and complement fixation tests. In serum chelated by 10 mM EGTA and 10 mM MgCl-2 (10 mM MgEGTA) activation by the classical pathway was blocked, but activation of C3PA and C3 occurred normally. By radial immunodiffusion assay, consumption of C3 and properdin was demonstrated to be similar to consumption in nonchelated sera. By immunoelectrophoresis, C3PA and C3 were shown to be activated by CoF in serum chelated with 6 mM but not with 10 mM EGTA without added Mg++. Inulin and endotoxin did not result in activation of either C3PA or C3, while C3PA but not C3 was activated by zymosan in the presence of 10 mM EGTA without Mg++ added. Consumption of properdin and C3, measured by radial immunodiffusion, was inhibited by 6 to 10 mM EGTA following activation by inulin, but not following activation by zymosan. The usefulness of 10 mM MgEGTA-chelated serum for the selective investigation of the alternate pathway in chemotaxis was demonstrated.

Blood Protein Electrophoresis↗
PubMed1974

Influence of the alternate complement pathway in opsonization of several bacterial species.

In normal human serum chelated with magnesium (10 mM) and ethylene glycotetraacetic acid (10 mM) (MgEGTA), the classical pathway of complement activation is blocked; however, the alternate pathway of complement activation is intact. Diplococcus pneumoniae, Staphylococcus albus, Streptococcus viridans, Streptococcus faecalis, and Serratia marcescens were opsonized in normal human serum containing 10 mM MgEGTA. In contrast, Staphylococcus aureus and Pseudomonas aeruginosa were poorly opsonized in human serum chelated with 10 mM MgEDTA. Therefore certain bacterial species appear to require the classical pathway of complement activation to be opsonized and other bacterial species utilize the alternate pathway of complement activation.

Acetates↗
PubMed1974

Effect of protein A on adsorption of bacteriophages to Staphylococcus aureus.

Experiments were performed to determine if protein A influenced the association of bacteriophages with Staphylococcus aureus. Bacteriophage adsorption was compared in a S. aureus strain rich in protein A and mutants of this strain with very little protein A, in a strain with little protein A, and in mutants of this strain with increased protein A. In addition, the effect of growth in mannitol-salt broth and trypsin digestion (known to reduce protein A) on bacteriophage absorption was measured. There was an inverse relationship between protein A content of strains and the quantity of bacteriophage absorbed. However, no inhibition of staphylococcal phages was obtained with purified soluble protein A. Protein A as a surface component rendered the bacteria more resistant to adsorption of staphylococcal typing phages presumably by masking the phage receptor sites. When protein A-deficient mutants were incubated with bacteriophages, there was survival of staphylococci with increased protein A content probably due to a selective action.

Adsorption↗
PubMed1974

Prevention of bacteriophage adsorption to Staphylococcus aureus by immunoglobulin G.

Normal human and rabbit sera when incubated with Staphylococcus aureus inhibit the adsorption of bacteriophages. The bacteriophage adsorption was also inhibited by separated normal immunoglobulin M (IgM), F(ab')(2), and Fab-fragments of IgG. No inhibition was obtained with myeloma IgG or Fc-fragments of normal human and rabbit IgG. The results indicate that the serum inhibition of bacteriophage adsorption to S. aureus is not due to a binding of IgG to protein A on the surface of S. aureus.

Adsorption↗
PubMed1973

Tetracyclines and host-defense mechanisms.

The effects of different tetracyclines on the bactericidal action of serum and on phagocytosis and intracellular killing of bacteria were investigated. Opsonization, phagocytosis, and intracellular killing were not significantly affected by any of the investigated tetracyclines. The bactericidal action of serum on Escherichia coli was substantially reduced by all tetracyclines investigated. In this respect, doxycycline had a much more pronounced action than the other tetracyclines. The serum bactericidal effect could be completely restored by addition of Mg(2+).

Blood Bactericidal Activity↗