Search PubMed⌕ Search

Biomedical subjects

W Opferkuch

Publications and source records attributed to W Opferkuch.

At least 73 records · Page 4Linked to original sources
PubMed1987

Influence of beta-lactam antibiotics and ciprofloxacin on cell envelope of Escherichia coli.

The effects of subinhibitory concentrations of different beta-lactam antibiotics and one quinolone on the quantitative composition of the outer membrane (OM) of two strains of Escherichia coli, on lipid translocation into the OM, and on the production of capsular K1 polysaccharide were studied. The phospholipid/amino acid ratio was reduced in almost all OM preparations from antibiotic-treated bacteria. In one strain, antibiotic treatment increased the lipopolysaccharide/amino acid ratio. The amount of peptidoglycan fragments bound to the OM was increased by all the antibiotics. In pulse-chase experiments with a radioactive lipid precursor, ciprofloxacin, imipenem, and aztreonam inhibited phospholipid translocation into the OM. Furthermore, imipenem, cephaloridine, and ciprofloxacin induced a pronounced reduction of the production of capsular K1 polysaccharide. Thus, antibiotics seem to induce marked changes of the quantitative composition of the cell envelope of E. coli. Possible connections of these data with findings on the influence of antibiotics on functional parameters of the host-parasite relationship such as OM immunogenicity and serum resistance are discussed.

Amino Acids↗
PubMed1987

Monoclonal antibody to human renal glomeruli cross-reacts with streptococcal M protein.

Two murine monoclonal antibodies (immunoglobulin M) evoked against human kidney tissue were examined for cross-reactivity with group A streptococci. A glomerulus-specific antibody, PMII.40.H.2, cross-reacted in an enzyme-linked immunosorbent assay with purified pepsin-extracted M proteins from type 6 and 12 streptococci, but not type 1, 3, 5, 19, and 24 M proteins. The cross-reactive monoclonal antibody also opsonized type 6 and 12 streptococci, indicating that it was directed against protective M protein epitopes that were exposed on the surfaces of these organisms. A control antibody, which was tubule specific, did not cross-react with any of the purified M proteins, nor did it opsonize any of the serotypes of streptococci tested. Western immunoblot experiments identified the glomerular cross-reactive antigen as a 43-kilodalton protein. The results demonstrate that M protein of group A streptococci and glomerular antigens of the human kidney possess cross-reactive determinants.

Animals↗
PubMed1986

[Clinical experience with imipenem/cilastatin in the treatment of severe infections in general surgery].

In a prospective study 43 patients (19 men, 24 women) suffering from severe bacterial infections such as peritonitis (n = 16), soft tissue infection (n = 12), pneumonia (n = 7), septicemia (n = 6), catheter sepsis (n = 2), cholangitis (n = 4), osteomyelitis (n = 3), complicated urinary tract infection (n = 2) or endocarditis (n = 1) were treated t. i. d. with short-time i. v. infusions of 0.5 g imipenem/cilastatin for five to 37 days (means = 9). All the patients were cured or significantly improved following therapy with imipenem/cilastatin alone or in combination with surgical intervention. The most frequent isolates were Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis, Staphylococcus aureus, Staphylococcus epidermidis and Streptococcus faecalis. 58 (83%) of the 70 pathogens isolated initially were eliminated. The 12 microorganisms (gram-negative aerobic bacteria) which persisted were non-contributory to the course of the infection and had MICs between 0.32 and 4 mg/l. The MICs for 60 isolates were less than or equal to 1 mg/l; the MICs for nine isolates were in the range of 2 to 8 mg/l. One S. epidermidis isolate presented primary resistance to imipenem (MIC 16 mg/l). The tolerability was good. Phlebitis was observed in one case only. Based on our experience we conclude that monotherapy with imipenem/cilastatin at a dosage of 0.5 g t. i. d. is appropriate for the treatment of severe bacterial infections.

Adolescent↗
PubMed1986

Influence of beta-lactam antibiotics and ciprofloxacin on composition and immunogenicity of Escherichia coli outer membrane.

The effects of subinhibitory concentrations of different beta-lactam antibiotics and one quinolone on the sedimentation of outer membranes (OMs) of Escherichia coli and on the qualitative properties and immunogenicity of OM components were studied. Membranes were prepared by osmotic lysis of plasmolyzed bacteria. OM and cytoplasmic membrane vesicles were separated by sucrose density ultracentrifugation. Two peaks of OM vesicles with different buoyant densities could be isolated; the quantitative contribution of these to the total OM varied, depending upon the growth phase. In early log phase, the OM consisted mainly of lighter material; in late log and stationary phases, the OM consisted mainly of heavier material. Moxalactam, imipenem, and ciprofloxacin inhibited the formation of heavier material in all growth phases. The immunogenicity of OM vesicles was tested in mice by the hemolytic plaque test. The lighter OM material was markedly less immunogenic than the heavier OM material. The vesicles from antibiotic-treated bacteria and those from early-log-phase cells were less immunogenic than vesicles from untreated late-log-phase and stationary-phase bacteria. These changes were found for the immune response against lipopolysaccharides, as well as against OM proteins. Thus, the immunogenicity of OM components seems to be dependent upon the quantitative composition of lighter and heavier compounds, which is strongly influenced by growth phase and treatment with certain antibiotics.

Animals↗
PubMed1986

[Characterization of imipenem resistance in Pseudomonas aeruginosa: decreased phenotypic expression of outer membrane proteins D1 and D2].

Imipenem-resistant variants can be selected from clinical Pseudomonas aeruginosa isolates in a frequency of 10(-8) to 10(-7) and 10(-5) in a single strain. In any case, there was no cross resistance between imipenem and other beta-lactams. In all IMI variants the induction potency of imipenem for the chromosomally-mediated Id beta-lactamase was markedly diminished as compared to the corresponding parent strains. Moreover, in all imipenem-resistant variants as well as in imipenem-resistant clinical isolates phenotypic expression of either a 46,000 dalton or a 47,000 dalton outer membrane protein was marginal; these proteins could be identified as proteins D1 and D2. These findings suggest a penetration barrier responsible for imipenem-resistance in Pseudomonas aeruginosa.

Bacterial Outer Membrane Proteins↗
PubMed1985

Influence of antibody and complement components on phagocytosis and chemiluminescence of macrophages.

Macrophages are known to release reactive oxygen species (O2-, 1O2, H2O2, OH.) in response to various membrane stimuli. However, our studies show that phagocytic stimulation of macrophages is not necessarily accompanied by a stimulation of the oxidative burst. Whereas IgG-opsonized erythrocytes were capable to induce phagocytosis and a chemiluminescence response, both being dependent on the number of IgG bound per erythrocyte, C3b-bearing erythrocytes were well ingested but failed to induce any chemiluminescence reaction. Furthermore, stimulation of macrophages, via the Fc-receptors, seems to alter their functional state in regard to the activation of a receptor, which enables them to recognize membrane lesions on the target erythrocyte. The presence of IgG and membrane lesions, e.g. the C5b-9-complex of complement, induced a marked increase in chemiluminescence compared with stimulation by IgG-bearing particles alone. The augmented response of macrophages was at least in part due to an additional release of H2O2, which was not liberated in response to IgG-bearing erythrocytes. This "lesion recognizing receptor" in the macrophage membrane could not be activated by stimulation of C3b-receptors, indicating its functional linkage to the Fc-receptors.

Animals↗
PubMed1985

Isolation and separation of physicochemically distinct fimbrial types expressed on a single culture of Escherichia coli O7:K1:H6.

The fimbrial (pili) profile of a single strain of Escherichia coli O7:K1:H6 (WF96) was evaluated. Fimbriae were isolated by sucrose density gradient ultracentrifugation, purified from flagellae by the use of 0.4% sodium dodecyl sulfate (SDS), and separated into distinct fimbrial types. Analysis of the purified WF96 fimbriae by SDS-polyacrylamide gel electrophoresis revealed two polypeptide bands with molecular weights of 16,000 and 21,000. Treatment of the fimbrial mixture with saturated guanidine hydrochloride resulted in the appearance of a third band with a molecular weight of 19,500. The relative susceptibilities of the WF96 fimbrial types to disrupting chemicals (octyl-glucoside, urea, SDS, and guanidine hydrochloride) were assessed by exposure of the fimbrial mixture to each agent, separation of the depolymerized fimbriae from intact fimbriae by gel filtration on Sepharose CL-4B, and identification of the disaggregated fimbrial types by SDS-polyacrylamide gel electrophoresis of column fractions. The physicochemical heterogeneity of the three fimbrial types coexpressed on WF96 was exploited to develop a method for separation of individual fimbriae.

Bacterial Proteins↗
PubMed1985

Three-dimensional structure of fimbriae determines specificity of immune response.

We recently described how a fraction of isolated fimbriae from a multifimbriated strain of Escherichia coli O7:K1:H6 (WF96) could be subdivided by sequential disaggregation in disrupting agents into individual subunits with different molecular weights. In this study, antibodies were raised in rabbits against these isolated fimbrial subunits and against purified intact WF96 fimbriae. These sera were tested by Western blot analysis or by enzyme-linked immunosorbent assays for reactivity against the following antigens: intact WF96 fimbriae, dissociated WF96 fimbriae, dissociated and reaggregated WF96 fimbriae, the WF96 21K fimbrial subunit, reaggregated WF96 21K subunits, the WF96 16K subunits, reaggregated WF96 16K subunits, intact fimbriae from four other E. coli strains, and deaggregated fimbriae from these strains. We found that antibody against intact WF96 fimbriae only reacted strongly with intact WF96 fimbriae, depolymerized and reaggregated WF96 fimbriae, or reaggregated fimbrial subunits; no reactions were evident with intact fimbriae from four other E. coli strains. Conversely, antisera prepared against the WF96 16K subunit and against the WF96 21K subunit did not react with intact WF96 fimbriae or with depolymerized and reaggregated WF96 fimbriae, but did react with homologous isolated subunits. One cross-reaction between fimbrial subunits was apparent: anti-WF96 16K subunit bound to a 21K subunit of deaggregated fimbriae, from another E. coli strain. Taken together, the findings indicate that the three-dimensional structure of the fimbrial preparation used to immunize animals determines the specificity of the immune response.

Electrophoresis, Polyacrylamide Gel↗
PubMed1985

Comparative evaluation of recently developed quinolone compounds--with a note on the frequency of resistant mutants.

The antibacterial activity of the new quinolone compounds enoxacin, norfloxacin, ofloxacin and ciprofloxacin was evaluated in 300 Enterobacteriaceae, 50 Pseudomonas aeruginosa, 30 Acinetobacter spp., 15 Haemophilus influenzae, 50 Streptococcus faecalis, and 70 Staphylococcus aureus isolates and compared to that of nalidixic acid, gentamicin and various beta-lactam compounds. Moreover, the rate of spontaneous mutants resistant to quinolone compounds was evaluated. In concentrations only insignificantly exceeding the minimal inhibitory concentrations (MIC), mutants could be isolated rather frequently (approx. 10(-6) fold); in concentrations of at least 10 times the MIC resistant mutants were barely detectable. In general, the mutants exhibited a 4- to 8-fold increase of the MIC as compared to the wild strain. In S. faecalis mutants were not detectable, whereas they occurred in low frequency (less than 10(-8) fold) in S. aureus strains. In all mutants there was almost, but not entirely, complete cross-resistance between the quinolone derivatives.

Acinetobacter↗
PubMed1985

Influence of beta-lactam antibiotics, fosfomycin and vancomycin on the adherence (hemagglutination) of Escherichia coli-containing different adhesins.

The adherence of Escherichia coli of certain adhesin types can be influenced by subinhibitory concentrations of beta-lactam antibiotics. Subinhibitory concentrations (1/4MIC) of those penicillin and cephalosporin compounds which lead to filament formation increase mannose-sensitive adhesion (MS+). Antibiotics with ovoid cell formation did not change or only slightly reduced MS+ adherence. Strains with mannose-resistant (MR+) adhesins were not affected by these antibiotics. Only azthreonam increased the adherence of both MS+ and MR+ strains. Vancomycin and fosfomycin reduced the adherence of all strains tested. The degree of change was strain and antibiotic specific. No relation could be detected between the changes of adherence and the changes of hydrophobicity under the influence of antibiotics. Electron microscopic investigation has not yet yielded an explanation of the observed phenomenon.

Adhesiveness↗
PubMed1985

[Adherence of E. coli strains with various adhesins to macrophages from bone marrow and the cell line P 388D1].

The adherence of E. coli with different hemagglutination patterns to mouse-bone-marrow-derived macrophages and macrophages of the cell line P 388D1 was investigated. The bacterial strains used showed different adherence to macrophages or red blood cells. MS-adhesins identified by hemagglutination tests were also involved in the attachment of bacteria to macrophages. In addition, strains containing both, MS and MR adhesins, simultaneously showed a participation of their MR-adhesins in adherence to macrophages. This could be shown by inhibition experiments with alpha-D-mannose. Bacteria of strain D 133 failed to induce hemagglutination of any source of erythrocytes tested, though MR-adherence to macrophages could be found. In contrast, other strains known to carry MR-hemagglutinins on their cell surface, did not attach to macrophages, even if much higher numbers of bacteria were used. A linear correlation between the amount of bacteria used and the number of adherent bacteria/macrophage was detectable. The number of bacteria found on the macrophages differed according to the population of macrophages studied, indicating differences in the expression of corresponding receptors in the macrophage plasma membrane. In order to investigate the role of fimbriae in adherence, bacteria were used which had been grown under fimbriae suppressing conditions. Some of the bacterial strains showed a 10 to 30 fold reduction in adherence to macrophages upon this treatment, indicating the importance of fimbriae-associated adhesins in the interaction of bacteria and phagocytes. On the other hand, three bacterial strains could be identified, whose adherences was not influenced by such culture conditions. This means that beside fimbrial adhesins even membrane bound adhesins could be involved in the phagocytic process.

Adhesins, Escherichia coli↗
PubMed1985

Bile levels of imipenem following different dose regimens.

Seventeen patients received either 500 mg (9 patients) or 1000 mg (8 patients) of imipenem following bile duct surgery with indwelling Kehr-T-drainage which permitted the measurement of bile levels. Bile and blood specimens were taken at the following time intervals: control value prior to the 20 min-imipenem-infusion, then at 10, 15, 20, 30, 45, 60, 90, 120, 150, 180, 240 and 300 min after administration of imipenem. In addition, a blood specimen was drawn after 360 min. Three patients of the 500 mg-group and 6 patients of the 1000 mg-group received a second dose after 4 h. The specimens were taken at the same intervals as mentioned above. It was shown that a spaced dose of 500 mg imipenem thrice daily would be sufficient to treat infections by sensitive pathogens of the bile ducts.

Aged↗
PubMed1985

[Classification, diagnosis and therapy of pneumonia].

The different patterns of pneumonia are classified and show the various manifestations of the disease, indicating the necessary specific diagnostic procedures. Only by description and recognition of the possible pathogenic agents, an adequate therapy can be initiated as described in the last chapter.

Aminoglycosides↗
PubMed1984

Human C4 polymorphism: pedigree analysis of qualitative, quantitative, and functional parameters as a basis for phenotype interpretations.

Ten families with 82 members were investigated for C4A- and B polymorphism in a blind trial. Phenotyping was done on neuraminidase treated sera by immunofixation and simultaneously by hemolytic overlay electrophoresis. In addition Rg, Ch, BF, C2, HLA-A, B, C, DR, and GLO were determined. After decoding the samples the reliability of blind typing was found to be 84.4% according to segregation patterns. Inconsistencies occurred mostly when A4, A2, or A92 were present. The detection of silent A*Q0 and B*Q0 alleles was more critical than that of "difficult" allotypes. The quantitation of the C4A/B ratio by densitometry of stained gels or by conventional immunochemical measurements of serum C4 level could not substantially improve the identification of A*Q0 or B*Q0. C4 dependent activity in radial diffusion hemolysis showed satisfactory correspondence with the number of expressed C4B alleles. At least three haplotypes with two C4A genes (duplicated A genes) were observed as ascertained from offspring analysis in accordance with the MHC segregation pattern. Individuals with the duplicated C4A gene (C4A*3, A*2, in the absence of any other expressed A allele or together with C4A*92) showed only partial inhibition of Rodgers antisera. Partial inhibition of Chido antisera was seen in individuals with C4B 2 (in the absence of other B allotypes). The findings support the hypothesis of at least two structural C4 loci. They also demonstrate the inconsistency of quantitative data in the recognition of silent alleles.

Alleles↗
PubMed1984

Influence of spontaneous and inducible beta-lactamase production on the antimicrobial activity of recently developed beta-lactam compounds.

The activity of 9 recently developed beta-lactam compounds was evaluated in 185 ampicillin-resistant isolates of Enterobacteriaceae. Moreover, in all strains, spontaneous and inducible beta-lactamase production was quantified and correlated with the minimal inhibitory concentration (MIC) of each compound. In most species, no correlation could be observed between spontaneously produced beta-lactamase and the MICs, with the only exceptions of Serratia spp. and Morganella morganii isolates for methoxyimino cephalosporins and azthreonam. On the other hand, the increase of MICs of third-generation cephalosporins and azthreonam correlated well with the total amount of enzyme produced. With respect to temocillin and the penem compound Sch 29 482, there was a significant correlation of enzyme production and MICs only among the Citrobacter spp. isolates. It can be assumed that the effectiveness of the new agents is not only due to the low rate of hydrolysis, but also to the rapid binding to the lethal target.

Anti-Bacterial Agents↗