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Biomedical subjects

W Schaeg

Publications and source records attributed to W Schaeg.

At least 37 records · Page 2Linked to original sources
PubMed1977

A radioimmunoassay for tetanus antibodies using protein A - containing Staphylococcus aureus.

To measure tetanus antibodies a trace amount of 125I-labeled tetanus toxin is mixed with appropriate dilutions of human serum or blood. The labeled antigen-antibody complexes are adsorbed to heat-killed staphylococci (Cowan I) via their surface protein A. The radioactivity of the washed solid phase is a function of the initial antibody concentration. The test allows the measurement of 6 X 10(-0) U of tetanus antitoxin in a volume of 0.03 ml. In order to avoid possible interferences, serum has to be diluted 20-fold before use. Taking that into account, the real border limit of sensitivity is 4 X 10(-3) U/ml serum. Antibodies may be measured in serum, in plasma, and even in heparinized blood. As to its sensitivity, the test compares well with the toxin neutralization procedure. It is superior to the previous radioimmunologic, enzymoimmunologic, and hemagglutination techniques with respect to sensitivity and reproducibility. It reflects the values obtained in the toxin neutralization test better than the other in vitro procedures, as shown by parallel assays of 17 sera.

Humans↗
PubMed1977

A staphylococcal radioimmunoassay for detection of antibodies to Mycoplasma pneumoniae.

A radioimmunoassay (RIA) which depends on the property of protein A of Stapbylococcus aureus to combine with the Fc-fragment of immunoblobulins was developed. This technique was employed to measure antibodies in human and various animal sera. It coulb be demonstrated that the staphylococcal RIA was at least as sensitive as the previously decribed radioimmunoprecipitation technique in detecting antibodies to M.pneumoniae in human sera. In addition, antibodies to M. pneumoniae could be demonstrated in sera of hamsters intranasally inoculated with the organisms. Antibodies could also be demonstrated in rabbit sera after immunization with M.pneumoniae. The test proved to the considerably more sensitive than conventional tests for detection of antibodies to the organisms. The test requires only small amounts of reagents and is relatively inexpensive.

Animals↗
PubMed1977

Solid phase radioimmunoassay for cyclic AMP using staphylococcal protein A-antibody adsorbent.

A radioimmunoassay for cyclic AMP has been developed using protein A containing staphylococci as an immunoabsorbent. Protein A containing heat-killed staphylococci (Cowan I) are coated with rabbit antiserum raised against the 2'-O-succinyl derivative of cyclic AMP coupled to human serum albumin. After washing with a Tween 20 containing buffer, antibody coated staphylococci are diluted with heat-killed staphylococci devoid of protein A (staphylococcus epidermidis) and mixed with [125I]-2'-O-succinyl cyclic AMP tyrosine methyl ester, standards or unknowns. At the end of the incubation, separation of bound and free labelled antigen is achieved by bound and free labelled antigen is achieved by centrifugation. The results are comparable to those obtained with a precipitation assay using polyethylenglycol 6000. Acetylation prior to radioimmunoassay increases sensitivity about 80-fold. 50% depression of zero dose binding occurs at 15--16 femtomoles acetylated cyclic AMP. The crossreactivity with cyclic GMP, ATP, ADP, 5'-AMP and adenosine is extremely low. The present technique is an attractive alternative to the second antibody method or polyethylenglycol precipitation.

Acetylation↗
PubMed1977

[Studies on the activation of complement by encapsulated and non-encapsulated staphylococci after their extraction with guanidinium chloride (author's transl)].

All demonstrable enzymes and toxins of encapsulated staphylococci (KS) were removed by extraction with guanidinium chloride. The capsules, however, remained apparently intact on the extracted (KS-Gu) staphylococci (fig. 1), as well as clumping factor and protein A. KS and KS-Gu failed to activate complement in the absence of specific antibodies. They showed neither immunadherence (table 1) nor agglutination by an antiserum against C3 (table 2). KS and KS-Gu had no significant chemotactic effects in vitro upon bovine granulocytes (fig. 2).

Agglutination↗
PubMed1977

[Purification of protease from staphylococcus aureus (author's transl)].

380 (80%) of 475 Staphylococcus aureus cultures isolated from humans, cattle and dogs were proteolytically active either on casein or gelatin or both (table 1). Protease-activity could also be demonstrated in experimental body-cavities of rabbits (fig. 1). The enzyme-activity was estimated with azocasein. Protease from S. aureus, M 135 precipitated from the culture supernatant with ammonium sulfate at 65% saturation (table 2). It was purified by 2 filtrations on Ultrogel AcA 44 (fig. 2,3) and subsequent isoelectric focusing between pH 3.5-7.0 (fig. 4). The purified protease yielded only 1 line in the SDS-polyacrylamidegel-electrophoresis, in the gelatin-polyacrylamidegel-electrophoresis and in the double immuno-diffusion test (fig. 5). Its isoelectric point was at pH 4.6, and its highest proteolytic activity between pH 7.5-8.3. The molecular weight was estimated by SDS-polyacrylamidegel-electrophoresis to be near 29.000. The protease-activity was completely inhibited in the presence of EDTA, partially inhibited by Cu2+ and Zn2+ and increased by Mn2+ (table 3).

Animals↗
PubMed1977

[Effects of capsules of Staphylococcus aureus on the rosette formation with B-lymphocytes and macrophages (author's transl)].

After extraction with guanidium chloride nonencapsulated Staphylococcus aureus (S-Gu) and yeast cells (Hefe-Gu) reduced the hemolytic complement activity of normal human and guinea pig sera much more (fig 1) than encapsulated S. aureus (KS-Gu). Following incubation in the fresh sera S-Gu, Hefe-Gu and guanidinium chloride-extracted S. epidermidis, contrary to KS-Gu, had activated C3 on their surface. Therefore, they formed rosettes with human B-lymphocytes (fig. 2,3,4) and peritoneal macrophages from guinea pigs. The adherence-reactions were less frequent. if the pre-incubation was conducted in the heat-inactivated (30 min, 56 degrees C) sera (table 1,2). After pre-incubation in the absence of serum only the protein A-positive S-Gu formed rosettes with B-lymphocytes.

Animals↗
PubMed1977

[Evaluation of phagocytosis of Staphylococcus aureus with the aid of lysostaphin (author's transl)].

The Staphylococcus aureus strains HV 1 and K 807 were lyzed by lysostaphin. S. epidermis E 1 and staphylococci extracted with guanidinium chloride were resistant to lysostaphin-induced lysis. In the phagocytosis of S. aureus lysostaphin proved to be most useful for the differentiation between engulfed and extracellular staphylococci, particularly those attached to the surface of the polymorphonuclear granulocytes. It enabled a better recognition of the phagocytized staphylococci and therefore a more precise analysis of the phagocytosis experiments. A further improvement in the evaluation of phagocytosis was possible by the use of radioisotope labelling of staphylococci. This technique in combination with lysostaphin, might be useful for large-scale phagocytosis studies.

Animals↗
PubMed1977

["Clumping factor"-reactions using staphylococci after their extraction with guanidiniumchloride (author's transl)].

Staphylococci of strain K 807 (ATCC: 31243) have much "clumping factor" (CF) on their surface. Extraction of the staphylococci with 6 M guanidinium chloride, removed all soluble substances, including coagulase, without reduction in CF-activity. The extracted staphylococci proved to be most suitable for the quantitative determination of fibrinogen and fibrin degradation products in a microtiter procedure (fig. 2). The CF-test with staphylococci of strain K 807 was more sensitive compared with the hitherto used strain Newman D2C (table 1). After staining with "Astrazonrot (BBL)" no loss of CF occurred. With the stained staphylococci the CF-reactions became more distinctly visible and gave sharp endpoints.

Agglutination↗
PubMed1977

[No or little chemotactic activity of staphylococcal substances on macrophages (author's transl)].

Chemotactic effects of staphylococcal substances on macrophages from guinea pigs were studied using modified Boyden-chambers. Filters with an average pore-diameter of 12 micrometer allowed optimal migration of the macrophages. The macrophages were obtained from the peritoneal exsudates 96 h after stimulation with sodium-caseinate (fig. 1) and subsequently concentrated by centrifugation in a ficoll-ronpacon gradient (fig. 2, table 1). Casein had strong chemotactic effects on the macrophages with and without fresh guinea pig serum (fig. 3). Staphylococci, before and after extraction with guanidinium chloride, purified protein A and capsular substances were neither cytotaxic nor cytotaxigenic (in the absence resp. presence of fresh serum). Culture supernatants and staphylococci after incubation with their homologous antiserum proved cytotaxigenic, also lysates of granulocytes from the blood. Lysates of granulocytes from the peritoneal exsudates of guinea pigs were strongly cytotaxigenic for the macrophages.

Animals↗
PubMed1975

[Effects of staphylococcal leucocidin in mice (author's transl)].

After intraperitoneal injections of mice with paraffin-oil and sodium caseinate the numbers of macrophages and granulocytes increased respectively as well in their peritoneal exsudate as in their blood. On the other hand, cyclophosphamide markedly decreased the numbers of leucocytes. All mice were more susceptibel to infections with leucocidin (PVL-R)-positive staphylococci than to those with leucodidin-negative staphylococci of comparable hemolytic properties. Generally, mice with increased numbers of leucocytes were relatively more resistant to the staphylococcal infections. Concentrated PVL-R-leucocidin injected intraperitoneally into mice caused a temporary decrease in the number of leucocytes, especially granulocytes and their phagocytic activity.

Animals↗
PubMed1975

[Influence of "clumping factor" from Staphylococcus aureus on phagocytosis (author's transl)].

In phagocytosis experiments the pathogenic significance of the "clumping factor" (CF) of Staphylococcus aureus was studied. CF-positive staphylococci were engulfed considerably less by leukocytes from rabbits and cattle than CF-negative staphylococci. Equally, the engulfment of staphylococcal skeletons (SSk) coupled with partially purified CF was significantly less than that of the SSk. The SSk had been prepared by extraction of staphylocci with formic acid. By this method the SSk were freed of all substances associated with staphyloccal virulence. Before coupling with CF the SSk were activated by cyanogen bromide. These in vitro-observations could be confirmed by the corresponding phagocytosis studies in experimental body cavities of rabbits. Thus, CF apparently interfered with the engulfment of the staphylococci by the leukocytes.

Agglutinins↗
PubMed1975

[Cytotoxic effects of a leukocidin from Staphylococcus aureus (author's transl)].

In an attempt to improve the assay of leukocidin from Staphylococcus aureus a combined vital fluorochrome staining procedure with acridine organe and ethidium bromide was developed. It proved to be more suitable for the demonstration of leukocidic effects on leukocytes than phasecontrastmicroscopy. Damaged leukocytes fluoresced distinctly red and undamaged leukocytes green. With the fluorochrome-method leukocidic changes became also evident in some lymphocytes. These were not clearly demonstrated by phasecontrastmicroscopy.

Acridines↗