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W Köhler

Publications and source records attributed to W Köhler.

At least 19 recordsLinked to original sources
PubMed1992

Erythrogenic toxins A, B and C: occurrence of the genes and exotoxin formation from clinical Streptococcus pyogenes strains associated with streptococcal toxic shock-like syndrome.

We report the study of 53 clinical isolates of group A streptococci, all from patients with streptococcal toxic shock-like syndrome. The strains were analysed for the occurrence of the genes of erythrogenic toxins (pyrogenic exotoxins) types A, B and C and in vitro production of these toxins. In contrast to reports indicating that 85% of the toxic shock-like syndrome-associated isolates contained the erythrogenic toxin A gene, only 58.5% of our strains harboured this gene. The erythrogenic toxin C gene was detected in 22.6% of the isolates. Erythrogenic toxin A and erythrogenic toxin B were produced by 68.7% and 58.3% of the strains containing either gene. For all group A streptococci, irrespective of clinical association, the erythrogenic toxin B gene was detected in all the isolates tested. Thus, it is difficult to define a specific role for erythrogenic toxin B in toxic shock-like syndrome as there was no clear correlation between this disease and the presence of toxin genes. Our results suggest the existence of other pathogenic factor(s) produced by group A streptococci which may stimulate human peripheral T lymphocytes in a manner similar to that of erythrogenic toxins, thus explaining different observations in previous epidemiological genetic studies.

Amino Acid Sequence↗
PubMed1992

The characterization of two new low molecular weight proteins (LMPs) from Streptococcus pyogenes.

Two novel extracellular mitogenic substances were isolated from Streptococcus pyogenes strain NY-5 and characterized. The purification steps involved an initial enrichment of the proteins from culture supernatant by silica gel adsorption, followed by ion exchange chromatography and gel filtration. The purified materials were homogeneous in SDS-PAGE, showed estimated molecular weights of 12 kD and isoelectric points of 4.7 and 4.3, respectively. Both proteins (LMP-12k-4.3pI and LMP-12k-4.7pI) demonstrated lymphocyte transformation activity at a concentration of 0.1 microgram/ml. The LMP-12k-4.7pI showed a 69.2% homology of the amino acid sequence with that of a phosphocarrier protein of Staphylococcus aureus and with a total identity in the active centre. The same protein was also isolated from streptococcal group C strain H46A with an N-terminal amino acid sequence being identical. The LMP-12k-4.7pI demonstrated biochemical properties identical with those of the earlier described streptococcal pyrogenic exotoxin type D. The LMP-12k-4.3pI did not show such a clear relation to other functional proteins.

Amino Acid Sequence↗
PubMed1992

Separation of T-cell-stimulating activity from streptococcal M protein.

The superantigenic properties of M protein type 5 of Streptococcus pyogenes have been implicated as an important pathogenicity factor in streptococcal autoimmune diseases. Here we show that after a single purification step by affinity chromatography on immobilized albumin or fibrinogen, M protein has no mitogenic activity for T cells. We demonstrate that the superantigenicity of M proteins of type 5 and type 1 is due to contamination with the highly potent pyrogenic exotoxins of S. pyogenes in the range of 0.1 to 0.01%. These results raise a general caveat for work with these extremely active T-cell mitogens, because the mitogenicity of other streptococcal or staphylococcal proteins could be due to similar minute contamination with potent superantigens that are undetectable by any biochemical method but extremely effective in stimulating sensitive T cells.

Antigens, Bacterial↗
PubMed1992

A long-term observation of spontaneous oto-acoustic emissions (SOAEs).

In a follow-up study of 22 ears made after a mean interval of 68 months, spontaneous oto-acoustic emissions (SOAEs) showed marked changes. At follow-up visits, fewer SOAEs were recorded than at the first examination. As the set-up employed at follow-ups was much more sensitive, this observation gains even more weight, because--given identical cochlear structures--a greater number of SOAEs ought to have been recorded. In analogy to age-related high-frequency hearing loss, SOAEs recorded at the follow-up examination were found at lower frequencies. This was associated with yet another phenomenon: Precise frequency data (derived from a 4,000 line spectrum) available for 13 SOAEs (7 subjects) from the first examination showed that SOAE frequencies had dropped slightly in all subjects. In 5 of them the frequency drop was significant (p less than 1/1000 in each case).

Acoustic Stimulation↗
PubMed1992

[Atypical fractionation in advanced squamous-cell carcinomas of the head-neck area].

From May 1990 to May 1991, 23 patients with advanced, inoperable squamous cell cancers, clinically staged as III or IV, were treated by unconventional fractionation radiotherapy. Treatment consisted of a continuous hyperfractionated accelerated radiotherapy, delivering a total dose of 55.3 Gy within 17 consecutive days. In ten patients radiation therapy was combined with chemotherapy; 20 mg mitomycin C/m2, administered by intravenous bolus injection on day 5 of treatment. Apart from a confluent mucositis, treatment tolerance was good. Haematological toxicity from mitomycin C was minor and did not require any specific therapy. The mucosal reaction lasted six weeks (median duration) and was not thought to be increased by additional chemotherapy. In twelve of 23 patients a complete remission of the primary tumour was seen, in patients with lymph node metastases there was a complete response in 14 out of 20 patients. After a median follow-up of 18 months, ten of 23 patients have survived (8/23 without evidence of disease). Eleven patients have died due to local tumour progression and one patient died with distant metastases, being without evidence of local tumour. The advantage of this unconventional fractionation, which takes the described short potential tumour doubling time for head and neck cancers into account, is discussed.

Adult↗
PubMed1992

[Epidemiology and pathogenesis of streptococcal infection].

The appearance of the "streptococcal toxic shock-like syndrome" led to a growing interest in infections caused by Streptococcus pyogenes (group-A-streptococci). Since 1987 some 800 cases with a lethality of 20% or more were observed. Contrary to toxic scarlet fever the site of primary infection are the lower respiratory tract or soft tissue infections. Erythrogenic toxins and low molecular weight mitogens, inducing cytokines (IL-2, IL-3, IL-6, TNF-alpha, IFN-gamma) seem to be involved in the pathogenesis of these severe infections. Morphologically and culturally the strains isolated from cases of toxic shock-like syndrome cannot be differentiated from isolates of epidemic scarlet fever or sporadic cases. At the same time, when in Scandinavia an epidemic by S.pyogenes type 1 with many cases of toxic shock was observed, the same type caused a scarlet fever epidemic without complications in eastern Germany. Erythrogenic toxin type A or its toxoid, respectively, can be used for successful immunizations of rabbits. Another--antibacterial-immunization can be done with the M-protein of S.pyogenes, which is limited by its type-specificity. Streptococcal vaccination is required especially for developing countries with a high incidence of rheumatic fever. Infections due to Streptococcus agalactiae (group-B streptococci) are often underestimated though they have a first position in septicemia and meningitis of newborns. Taxonomy and nomenclature of streptococci are often changing; a list of the presently known species is presented in table I.

Animals↗
PubMed1991

Protein A-streptokinase fusion protein for immunodetection of specific IgG antibodies.

The streptococcal streptokinase gene truncated at its 5' end was fused to regions of the staphylococcal protein A gene encoding the Fc-binding domains A and B. The resultant fusion gene, when expressed in the Escherichia coli lacPO system or under the speA expression/secretion signals in S. sanguis, specified a bifunctional hybrid protein, SPA-SKC, capable of Fc binding and plasminogen activation. When used in immunoassays designed to titrate antisera raised against bovine chymosin, human serum albumin and fibrinogen, the assay using SPA-SKC compared well with that using a commercial SPA-enzyme conjugate. The simple preparative method together with its efficacy and ease of use, make SPA-SKC a potentially valuable detector reagent in quantitative immunology.

Antibodies, Anti-Idiotypic↗
PubMed1991

An evolutionary conserved mechanism of T cell activation by microbial toxins. Evidence for different affinities of T cell receptor-toxin interaction.

The enterotoxins produced by Staphylococcus aureus are the most potent mitogens known. They belong to a group of distantly related mitogenic toxins that differ in other biologic activities. In this study we have compared the molecular mechanisms by which these mitogens activate human T lymphocytes. We used the staphylococcal enterotoxins A to E, the staphylococcal toxic shock syndrome toxin, the streptococcal erythrogenic toxins A and C (scarlet fever toxins, erythrogenic toxins (ET)A, ETC), and the soluble mitogen produced by Mycoplasma arthritidis. We found that all these toxins can activate both CD4+ and CD8+ T cells and require MHC class II expression on accessory and target cells. However, T cells could be activated in the absence of class II molecules if the toxins ETA or SEB were co-cross-linked on beads together with anti-CD8 or anti-CD2 antibodies. Enterotoxins, toxic shock syndrome toxin and scarlet toxins stimulate a major fraction of human T cells, and show preferential, but not exclusive, stimulation of T cells carrying certain TCR V beta. In contrast, the mitogen of M. arthritidis, a pathogen for rodents stimulates only a minority of human T cells but activates a major fraction of murine T cells. Analysis of human T cell clones expressing V beta 5 or V beta 8 TCR showed that these clones responded also to those toxins that did not stimulate V beta 5+ and V beta 8+ T cells in bulk cultures. These results indicate that different TCR bind to these toxins with different affinities and that the specificity of the TCR-V beta-toxin interaction is quantitative rather than qualitative in nature. Taken together our findings suggest that these toxins use a common mechanism of T cell activation. They are functionally bivalent proteins crosslinking MHC class II molecules with variable parts of the TCR. Besides V beta, other parts of the TCR must be involved in this binding. The finding that murine T cells responded more weakly to the toxins produced by the human-pathogenic bacteria than to the Mycoplasma mitogen could indicate that the toxins have been adapted to the host's immune system in evolution.

Animals↗
PubMed1991

Scarlet fever and types of erythrogenic toxins produced by the infecting streptococcal strains.

Group A streptococcal strains were isolated from the throats of 46 children suffering from scarlet fever. For detection of erythrogenic toxins (ETs), the culture supernatants were concentrated 100 times by ethanol precipitation and solubilisation in acetate buffer. ELISA was used to identify ETA and double immunodiffusion to identify ETB and ETC. The presence of the ETA gene was detected by a specific DNA probe. ETA (alone or in combination with ETB and/or ETC) was found in 51.9% of the strains, ETB (alone or in combination with ETA and/or ETC) in 76.9% and ETC (in combination with ETA and ETB) in 28.9%. Only 5.8% of strains did not produce any detectable ET. In SDS-PAGE, supernatants of ETB-producing strains showed a pronounced band in either the region of the proteinase zymogen or the active proteinase. There was no correlation between the type of erythrogenic toxin and the serological M or T type of the producing strain. The mitogenic potency of culture supernatants did not differ significantly irrespective of the toxin type(s) present. Culture supernatants of strains without a detectable amount of the known ETs were highly mitogenic, indicating the production of other streptococcal mitogens. A correlation with clinical symptoms was determined with regard to exanthema and fever. Strains producing two or three toxins caused a more intense exanthema. Patient temperature was higher (greater than or equal to 38 degrees C) when the infecting strain produced ETB. The toxin-producing patterns of the strains of this study were compared with those isolated during the last epidemic outbreak of scarlet fever in East Germany.

Bacterial Proteins↗
PubMed1991

[Clinical aspects of appendicitis].

When evaluating 4232 appendectomies between 1977-1986 there were 12.5% perforations and in 19.3% the diagnosis was not justified. In 5.1% surgical intervention was done without acute appendicitis. The overall lethality was 0.5%, the cases of perforation 2.3%. The diagnosis of lethality was cardiopulmonary disease. In this follow up study we discuss possibilities of giving a secure diagnosis.

Abdomen, Acute↗
PubMed1990

Studies on the use of monoclonal antibodies in the investigation of blood stains contaminated by bacteria.

On the basis of some models (bacteria and animal blood groups), it was demonstrated that monoclonal antibody-preparations obviously possess a much higher specificity against the ABO-properties of human than the usual human antisera or lectins. The behaviour of polyclonal and monoclonal reagents for ABO-determination should now be tested in comparative studies using contaminated blood stain material. The results presented in this paper suggest advantages in using monoclonal antibodies.

ABO Blood-Group System↗