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M Kilian

Publications and source records attributed to M Kilian.

At least 127 records · Page 7Linked to original sources
PubMed1987

Microbiology of the early colonization of human enamel and root surfaces in vivo.

This study describes the predominant early microflora on human teeth on the basis of microbiologic identification of 1742 fresh isolates. The isolates were obtained from four dental students who carried test pieces of enamel and root surface in the oral cavity for 4, 8, 12, and 24 h. During the experimental periods oral hygiene was discontinued. Under equal conditions root surfaces were more heavily colonized than were enamel surfaces. However, the composition of the microbiota was the same. Within the first 24 h the microflora was dominated by streptococci and Gram-positive pleomorphic rods. S. sanguis contributed only 6-18% of the early colonizers whereas S. mitis and S. oralis varied between 24-42% and 1-27% (mean values), respectively. The relative proportion of S. oralis increased significantly within the observation period while the proportion of S. salivarius and arginine-positive S. mitis showed a declining tendency. Actinomyces species adsorbed to the tooth surfaces within the first 4 h but did not increase their relative proportions until after 8-12 h, possibly due to a long doubling time. In one individual, encapsulated bacteria resembling Stomatococcus mucilaginosus were observed among the early colonizers. The time-dependent shifts in the bacterial populations within 24 h corroborate parallel ultrastructural findings.

Bacteria↗
PubMed1987

Enzymatic and antigenic characterization of immunoglobulin A1 proteases from Bacteroides and Capnocytophaga spp.

Bacteroides and Capnocytophaga species have been implicated as periodontal pathogens. Some of these species possess immunoglobulin A1 (IgA1) proteases that are capable of cleaving the human IgA1 molecule in the hinge region, leaving intact Fc alpha and Fab alpha fragments. The purpose of this study was to characterize this activity. In addition to IgA1 protease activity in already known species, IgA1 protease activity was a feature of Bacteroides buccalis, Bacteroides oralis, Bacteroides veroralis, Bacteroides capillus, and Bacteroides pentosaceus. Results of immunoelectrophoretic and sodium dodecyl sulfate-polyacrylamide gel electrophoretic analyses suggested that all species cleave the alpha-chain at the same peptide bond, i.e., the prolyl-seryl bond between residues 223 and 224 in the hinge region. The Bacteroides proteases could be classified as thiol proteases, which were at the same time dependent on metal ions, while the Capnocytophaga proteases were metallo enzymes. None of the proteases were inhibited by the physiologic proteases inhibitors alpha 2-macroglobulin and alpha 1-proteinase inhibitor. Investigations with enzyme-neutralizing antibodies raised in rabbits against protease preparations from the respective type strains revealed that, despite otherwise identical characteristics, the IgA1 protease of each Bacteroides species was antigenically distinct. Bacteroides buccae and the two later synonymous species B. capillus and B. pentosaceus produced identical proteases. In contrast, IgA1 proteases from Capnocytophaga ochracea and Capnocytophaga sputigena strains were apparently identical, while Capnocytophaga gingivalis had a protease that differed from those of the other Capnocytophaga species.

Amino Acid Sequence↗
PubMed1987

Genetic relationships among the oral streptococci.

Genetic relationships and species limits among the oral streptococci were determined by an analysis of electrophoretically demonstrable variation in 16 metabolic enzymes. Fifty isolates represented 40 electrophoretic types, among which the mean genetic diversity per locus was 0.857. Mannitol-1-phosphate dehydrogenase was not detected in isolates of the sanguis species complex, and glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase were absent in species of the mutans complex. Clustering from a matrix of Gower's coefficient of genetic similarity placed the 40 electrophoretic types in 10 well-defined groups corresponding to the Streptococcus species S. mutans, S. sobrinus, S. cricetus, S. rattus, S. ferus, S. oralis (mitior), two distinct assemblages of S. sanguis strains, and two subdivisions of "S. milleri." The assignments of isolates to these groups were the same as those indicated by DNA hybridization experiments, and the coefficient of correlation between genetic distance estimated by multilocus enzyme electrophoresis and genetic similarity indexed by DNA hybridization was -0.897 (P less than 0.001) for 50 pairwise combinations of isolates. S. ferus, which is widely believed to be a member of the mutans complex, was shown to be phylogenetically closer to species of the sanguis complex.

Animals↗
PubMed1987

Interference of IgA protease with the effect of secretory IgA on adherence of oral streptococci to saliva-coated hydroxyapatite.

It has previously been shown that secretory immunoglobulin A (S-IgA) influences the sorption of oral streptococci to hydroxyapatite as well as to cell surfaces. The present experiments demonstrate that bacterial IgA proteases, which cleave S-IgA in the hinge region, are capable of interfering with this mechanism. This result was obtained with an IgA1 specific protease from Haemophilus influenzae and with a protease from Clostridium ramosum that cleaves IgA1 as well as IgA2 of A2m(1) allotype. The modulation of S-IgA-mediated effects by IgA proteases were studied by means of an in vitro method which permits quantitative determination of the sorption of radiolabeled oral bacteria to hydroxyapatite beads. Other authors have suggested that IgA protease-mediated effects may be explained by a strongly reduced antigen-binding capacity of released Fab alpha fragments. Here we present evidence that streptococci, after exposure to specific S-IgA and IgA protease, are coated with Fab alpha fragments.

Adult↗
PubMed1987

[Comparative evaluation of the diagnostic value of indirect and reverse ELISA for demonstrations of specific IgM antibodies in toxoplasmosis in man].

Two ELISA techniques were investigated comparatively regarding their IgM sensitivity and specificity in human toxoplasmosis. Results of the fractionated Toxo-IgM-IIF assay were used as a standard for comparison. In 96 of 264 specimens the Toxo-IgM-IIF assay was positive. Positive sera were investigated quantitatively, negative sera only in the serum dilution 1/50 in both the indirect and the reverse Toxo-IgM ELISA. Sensitivity of the indirect technique was calculated greater than 99% and specificity 97%. The corresponding values for the reverse technique were 66% for sensitivity and greater than 99% for specificity.

Enzyme-Linked Immunosorbent Assay↗
PubMed1986

Retained antigen-binding activity of Fab alpha fragments of human monoclonal immunoglobulin A1 (IgA1) cleaved by IgA1 protease.

Immunoglobulin A1 (IgA1) proteases may be important virulence factors of certain bacteria involved in the pathogenesis of meningitis, gonorrhea, destructive periodontal diseases, and some other infections affecting mucosal membranes. This study evaluated the antigen-binding activity of free Fab alpha fragments released from human myeloma IgA1 by IgA1 protease from Haemophilus influenzae. Six myeloma proteins with antibody activity against streptolysin O, alpha-staphylolysin, or streptococcal hyaluronidase were used. Complete cleavage of the IgA1 myeloma proteins in the hinge region of the heavy chain did not affect their antigen-binding capacity. The titers of neutralizing activity associated with free Fab alpha fragments were not significantly different from those of the intact IgA1 proteins. The retained antigen-binding capacity of cleaved IgA1 is an important factor in the understanding of how IgA1 proteases may interfere with the immune protection of mucosal membranes.

Antibodies, Bacterial↗
PubMed1985

Bacterial immunoglobulin A proteases monitored by continuous spectrophotometry.

IgA proteases were estimated in a turbid aqueous two-phase system with 10% polyethylene glycol-Tris buffer, where IgA spontaneously concentrates in microscopic spherical particles (less than 1 micron). After enzymatic cleavage of IgA into Fab alpha and Fc alpha fragments, these fragments are soluble and decreasing turbidity is observed. The reaction may be followed by conventional spectrophotometry. In this manner, IgA proteases may be estimated in 10 min. Examples of the utility of the method are given with results from inhibitor studies, estimation of Km and purification of IgA protease from Haemophilus influenzae.

Autoanalysis↗
PubMed1984

A rapid method for the detection and quantitation of IgA protease activity by macrobore gel-permeation chromatography.

A rapid assay to detect and quantitate immunoglobulin A1 (IgA1) protease activity was developed by the use of a high-performance gel-permeation chromatography column. The assay measured the disappearance of intact substrate and the emergence of cleavage fragments and the results could be expressed in absolute units. The utility of the assay was demonstrated in the partial purification of an IgA1 protease from a strain of Haemophilus influenzae.

Chromatography, Gel↗
PubMed1984

Relative proportions of Haemophilus species in the throat of healthy children and adults.

To determine normal proportions of pharyngeal Haemophilus species, qualitative and quantitative mapping of the species in the pharynx of ten healthy children and ten healthy adults was carried out using a selective and a non-selective medium. Haemophilus organisms were present in all samples, comprising approximately 10% of the total cultivable flora (range 0.6-36.9%). Haemophilus parainfluenzae was a member of the normal flora throughout life, constituting 74% of pharyngeal Haemophilus organisms. Haemophilus segnis and Haemophilus paraphrophilus occurred more frequently in samples from adults, whereas Haemophilus haemolyticus was present in only one sample. Non-encapsulated Haemophilus influenzae strains, usually of multiple biotypes, were present in 80% of the children but accounted for a mean of only 1.8% of the total flora. Their number decreased with increasing age; 40% of the adults harbored Haemophilus influenzae but only of a single biotype which constituted a minor proportion of the total flora (mean 0.15%). These findings suggest that host mechanisms can influence changes in the proportions of Haemophilus influenzae strains colonizing the host.

Adult↗
PubMed1984

Bacterium-induced cleavage of IgA in nasopharyngeal secretions from atopic children.

Immunoglobulin A forms the specific immune barrier of mucosal surfaces against microorganisms and potential allergens. Immunochemical studies of nasopharyngeal secretions (NPS) from 97 children showed enzymatic degradation of IgA in 18.6% of the samples. The observed fragments are characteristically released from IgA by the activity of specific IgA 1 proteases produced by certain bacterial species. A significantly higher prevalence (P less than 0.001) of IgA cleavage was observed in NPS from children with atopic diseases (61.5%) than in controls (11.9%). These results indicate that bacterium-induced local defects in the mucosal immune barrier of the upper respiratory tract may be a factor in the pathogenesis of some forms of atopic disease.

Bacterial Infections↗
PubMed1984

Immunoglobulin A1 protease activity in strains of Ureaplasma urealyticum.

Thirteen serovars of Ureaplasma urealyticum were analyzed for the ability to cleave human IgA. Strains of all of the serovars tested cleaved IgA 1 in the hinge region of the alpha-chain, resulting in intact Fc and monomeric Fab fragments. IgA 1 protease activity was also observed in concentrated cell-free extracts of spent cultivation medium, indicating that the IgA 1 protease was excreted into the medium during growth of the micro-organisms. Five clinical isolates of U. urealyticum obtained from urine, cervix, vagina, amniotic fluid, and synovial fluid were positive for IgA 1 protease activity. No proteolytic activity was observed against human IgA 2, IgG, or IgM. Strains of Mycoplasma fermentans, M. salivarium and seven serovars of M. hominis were negative for IgA 1 protease activity.

Immunoglobulin A↗
PubMed1984

Bacteremia caused by a beta-lactamase producing Haemophilus parainfluenzae strain of a new biotype. A case report.

A case of Haemophilus parainfluenzae bacteremia without known infectious focus is reported. Phenotypically, the isolated strain is a typical H. parainfluenzae except for its ability to produce indole and beta-lactamase. Beta-lactamase producing H. parainfluenzae organisms are encountered occasionally, but to the best of our knowledge this is the first reported blood culture isolate with this ability. We propose a new biotype (IV) of H. parainfluenzae to accommodate strains that are indole, urease and ornithine decarboxylase positive.

Aged↗
PubMed1984

Purification and characterization of an immunoglobulin A1 protease from Bacteroides melaninogenicus.

Attention has recently been focused on bacterial proteases with the capacity to cleave immunoglobulin A (IgA proteases) as possible pathogenic factors in bacterial meningitis, gonorrhoea, and destructive periodontal disease. Here, we describe a method for the rapid purification of a specific IgA1 protease from Bacteroides melaninogenicus. The IgA1 protease was purified 6,172-fold with a yield of 9% by ammonium sulfate precipitation, DEAE-ion exchange chromatography, and separation on a preparative TSK-G 3000SWG high-pressure gel permeation chromatography column. The enzyme was specific for human IgA1 and cleaved a prolyl-seryl peptide bond in the hinge region of the alpha 1 chain between residues 223 and 224. The molecular weight of the enzyme was 62,000, the isoelectric point was 5.0, and the Km was 3.4 X 10(-6). The enzyme was active over a broad pH range and had maximal activity at pH 5.0. B. melaninogenicus IgA1 protease was classified as a thiol protease on the basis of its inhibition by traditional protease inhibitors and the fact that it was active only under reducing conditions.

Bacteroides↗