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Biomedical subjects

S S Pedersen

Publications and source records attributed to S S Pedersen.

At least 55 records · Page 3Linked to original sources
PubMed1990

IgG subclass antibodies to Pseudomonas aeruginosa in sera from patients with chronic Ps. aeruginosa infection investigated by ELISA.

ELISAs using subclass-specific monoclonal antibodies were developed for the quantification of human IgG1, IgG2, IgG3 and IgG4 antibodies to Ps. aeruginosa. We investigated the pattern of IgG subclass antibodies against Ps. aeruginosa in serum from patients with cystic fibrosis (CF), other patients with chronic Ps. aeruginosa infection, and healthy controls. Healthy controls and patients with CF but without Ps. aeruginosa infection showed no or very low titres of antibodies against Ps. aeruginosa. In the early stage of chronic Ps. aeruginosa infection, antibody titres in all four subclasses were significantly higher than either normals or CF patients without infection. Other patients with Ps. aeruginosa infection showed the same increased level of IgG subclass antibodies as CF patients in an early stage of infection. Sixteen patients (eight in good and eight in poor clinical condition) have been followed for an average of 13 years with multiple serum samples covering the pre-infection, early and late stages of chronic infection. Patients in a poor clinical condition showed significantly higher levels of IgG3 antibodies in the first year of infection and 2 years later also had significantly higher IgG2 antibody levels. We conclude that elevated levels of IgG2 and IgG3 antibodies to Ps. aeruginosa are a sign of poor prognosis in CF.

Adolescent↗
PubMed1990

Pseudomonas aeruginosa alginate in cystic fibrosis sputum and the inflammatory response.

Alginate, a viscous polysaccharide from mucoid Pseudomonas aeruginosa, may interfere with the host defenses in patients with cystic fibrosis and chronic P. aeruginosa lung infection. The alginate concentration in the sol phase of expectorated sputum was quantitated by a biochemical method and a newly developed enzyme-linked immunosorbent assay. There was a high degree of correlation between the methods, and the concentration of alginate ranged from 4 to 101 micrograms/ml with a median of 35.5 micrograms/ml when measured by enzyme-linked immunosorbent assay. Alginate could not be detected in the bronchial secretions from patients without P. aeruginosa infection. In vitro investigation of alginate did not show any activation of the alternative pathway of complement, as determined by a hemolytic kinetic assay and by testing for neutrophil chemotaxis. At a high concentration, P. aeruginosa alginate caused a slight activation of the classical pathway of complement. Alginate did not cause neutrophil chemotaxis by itself but was able to reduce the neutrophil chemotactic response to N-formylmethionylleucylphenylalanine and for zymosan-activated serum. P. aeruginosa and seaweed alginates were able to prime neutrophils for increased N-formylmethionylleucylphenylalanine-induced neutrophil oxidative burst, as determined by chemiluminescence. Because of its ability to prevent attraction of neutrophils to the site of infection, lack of complement activation, and ability to enhance neutrophil oxidative burst, alginate from P. aeruginosa may contribute to the persistence and pathogenesis of chronic P. aeruginosa infection in cystic fibrosis.

Alginates↗
PubMed1990

Immunoglobulin A and immunoglobulin G antibody responses to alginates from Pseudomonas aeruginosa in patients with cystic fibrosis.

Patients with cystic fibrosis have a high prevalence of mucoid, alginate-producing Pseudomonas aeruginosa that causes chronic infection of the mucosal surface of the lungs. We developed enzyme-linked immunosorbent assays (ELISAs) for determination in serum of immunoglobulin A (IgA) and IgG antibodies to alginate purified from P. aeruginosa and an ELISA for detection of IgA antibodies to a polyvalent P. aeruginosa standard antigen. Absorption experiments indicated that the assays were antigen and antibody specific and had analytical variations that ranged from 7 to 19%. Serum samples from 207 patients with cystic fibrosis, 100 healthy children, and 94 healthy adults were examined. The patients responded to P. aeruginosa infection with early IgA and IgG antibody responses that were significantly higher than in controls and noncolonized patients. Analysis of paired serum samples showed that infected patients had an increase in specific IgG and IgA antibodies that was significantly higher than in noncolonized patients. The serological data were analyzed for correlation with clinical condition; poor lung function was significantly associated with increased levels of IgA and IgG antibodies to P. aeruginosa alginate and to the standard antigen and with a relative excess of IgA antibodies to the standard antigen compared with IgA antibodies to P. aeruginosa alginate. The assays showed high predictive values if positive, but a negative test did not exclude infection, and the ELISAs should not be used for diagnostic purposes. Mucoid strains were present initially in the sputa of 28 of 54 infected patients with paired serum samples. These patients had a significant increase in anti-alginate antibodies, but it was not different from the increase seen in patients infected only with nonmucoid strains. Therefore, alginate may also be produced in vivo by nonmucoid P. aeruginosa. The study showed that early formation of IgA and IgG antibodies to P. aeruginosa alginate did not prevent development of chronic infection and that P. aeruginosa-specific IgA antibodies correlate with poor lung function.

Adolescent↗
PubMed1990

Induction of experimental chronic Pseudomonas aeruginosa lung infection with P. aeruginosa entrapped in alginate microspheres.

Alginate-producing, mucoid P. aeruginosa is frequently found in the lungs of patients with cystic fibrosis (CF), where it causes a chronic infection. The importance of alginate in the pathogenesis was demonstrated by the ability to establish chronic P. aeruginosa lung infection in rats if P. aeruginosa entrapped in minute alginate-beads were inoculated transtracheally. Alginate beads containing P. aeruginosa were formed by nebulizing a suspension of seaweed sodium-alginate and P. aeruginosa into a calcium solution. The alginate bead method of establishing infection was compared to an agar-bead method and proved to be quantitatively similar after 4 weeks. The ability of the two methods to induce formation of precipitins, IgA and IgG antibodies against P. aeruginosa antigens, including outer membrane proteins, flagella, exoenzymes and alginate, was assessed by crossed immunoelectrophoresis, enzyme-linked immunosorbent assay and immunoblotting. The two methods of inducing infection were comparable and infected rats had significantly higher antibody response than rats inoculated with sterile beads. We suggest that the alginate bead model closely resembles the later stages of CF-lung infection and that it offers the theoretical advantage of using a substance which is chemically similar to the alginate produced in vivo by P. aeruginosa.

Agar↗
PubMed1990

Immunology of Pseudomonas aeruginosa infection in cystic fibrosis.

Adherence of P. aeruginosa to the lining of the respiratory tract is probably mediated by interaction of pili or alginate with lactosyl and sialosyl residues on the respiratory cells. The toxins produced by P. aeruginosa (for example, elastase and alkaline protease) may play a key role during the initial persistent colonization as they interfere with important defense mechanisms. Neutralizing antibodies are eventually produced, and a poor prognosis is correlated to a pronounced antibody response. The bacteria are protected against the host's defense mechanisms by production of alginate which encapsulates microcolonies of P. aeruginosa in the lungs. During the chronic infection, toxins of P. aeruginosa probably play little if any direct pathogenic role, however, immune complexes seem to be a major trigger of chronic inflammation in the lungs. Proteolytic enzymes and oxygen radicals released from the abundance of neutrophils in the lungs are probably responsible for most of the tissue damage. The individual course of the chronic infection may be explained by regulatory mechanisms, such as cleavage of immune complexes by neutrophil elastase, and by the balance between the different IgG subclass-specific antibody responses.

Bacterial Adhesion↗
PubMed1989

Estimated risk of cross-infection with Pseudomonas aeruginosa in Danish cystic fibrosis patients.

During the period 1970-1987 the number of cystic fibrosis (CF) patients treated at the Danish CF Center increased from 54 to 226. The prevalence of patients with chronic P. aeruginosa infection (CF + P) increased from 35% to 59%, whereafter it decreased to 54%. The yearly incidence of new CF + P patients averaged 8.4% in 1970-1975, 17% in 1976-80, 6.5% in 1981-85, and 3% in 1986-87. These changes correlated to the increased "contact density" between CF + P and non-infected CF patients (CF-P) due to intensified treatment starting in 1976, and the reduced "contact density" due to separation of the two groups starting in 1981. The same trends were observed during an epidemic spread of a multiply resistant P. aeruginosa in the CF + P group, which was also interrupted by separation of two groups of patients, with and without the multiply resistant strain. The observed prevalences of CF + P in different age groups of patients are in accordance with a 20% incidence/year in patients older than three years. The highest probability of acquiring chronic P. aeruginosa infection was calculated to be 2%/day and the lowest 0.09%/day spent in the Centre. By employing a simple mathematical model of the spread of infectious diseases it can be shown, that the highest incidence of CF + P is present when the prevalence of CF + P is 20-80%, and that an increase in the total number of patients also increases the incidence of CF + P unless the patients are divided into smaller groups. The observations in the Danish CF Centre are in accordance with this model.

Cohort Studies↗
PubMed1989

Increased levels of IgG subclasses specific for Pseudomonas aeruginosa exoenzyme and polysaccharide antigens in chronically infected patients with cystic fibrosis.

IgG subclass levels to Pseudomonas aeruginosa alginate, alkaline proteinase, elastase and exotoxin A in sera of healthy adults, non-infected and infected cystic fibrosis patients were investigated by enzyme linked immunosorbent assay. Whereas healthy adults and non-infected cystic fibrosis patients revealed mostly negative IgG subclass levels to the four antigens, infected cystic fibrosis patients had significantly elevated IgG1, IgG2, IgG3 and IgG4 levels to both the protein antigens as well as the polysaccharide antigen. The study does not support previous findings of an impaired natural IgG2 response to polysaccharide antigen. The study does not support previous findings of an impaired natural IgG2 response to polysaccharide in chronically infected cystic fibrosis patients.

ADP Ribose Transferases↗
PubMed1989

Purification, characterization, and immunological cross-reactivity of alginates produced by mucoid Pseudomonas aeruginosa from patients with cystic fibrosis.

Alginates from nine mucoid Pseudomonas aeruginosa isolates from patients with cystic fibrosis were purified by repeated ethanol precipitation, nuclease digestion, anion-exchange chromatography, dialysis, and lyophilization. Uronic acid constituted 72% of the dry weight when mannuronolactone was used as the internal standard in the carbazole-borate assay for uronic acids. The average degree of acetylation was 16%, and the ratio of mannuronic acid to gluluronic acid was 4.7. No homopolymeric blocks of guluronic acid were found when analyzed by nuclear magnetic resonance spectroscopy. Contaminating proteins were denatured by heating, and during purification the content of protein relative to alginate fell from 566 to 0.9%. The content of lipopolysaccharide was 0.012%. No immunological or biological activity was attributable to the protein or lipopolysaccharide content as estimated by immunoblotting, enzyme-linked immunosorbent assay (ELISA), and a neutrophil chemotaxis assay. Rabbits were hyperimmunized with P. aeruginosa alginates and alginate from the seaweed Laminaria hyperborea, and an ELISA that detected alginate-specific antibodies was developed. Antibodies to P. aeruginosa alginate were detected by ELISA in 1:4,000 dilutions of serum from patients with cystic fibrosis with chronic P. aeruginosa lung infection. The serological cross-reactions between serum from the nine patients with cystic fibrosis and the corresponding P. aeruginosa alginates were investigated and showed considerable heterogeneity. This finding indicates that P. aeruginosa alginate from more than one P. aeruginosa strain should be used in serological tests. There was no serological cross-reactivity between P. aeruginosa and Laminaria hyperborea alginate in either rabbits or patients with cystic fibrosis.

Alginates↗
PubMed1989

Occurrence of a common lipopolysaccharide antigen in standard and clinical strains of Pseudomonas aeruginosa.

The lipopolysaccharide (LPS) of Pseudomonas aeruginosa PAO1 contains two species of O polysaccharide termed A and B bands. The high-molecular-weight B-band LPS determines the O specificity of the bacterium, while the antigenically distinct A-band LPS consists of only shorter-chain polysaccharides. Seven hybridomas secreting A-band-specific monoclonal antibodies were produced and used to study the LPS of standard and clinical strains. Although A-band antibodies did not agglutinate any of the serotype strains presently in the International Antigenic Typing Scheme, Western immunoblots revealed that 11 of the 17 serotype strains possessed A-band LPS. In a group of 250 clinical isolates from patients with cystic fibrosis, 170 (68%) had A-band LPS on the basis of agglutination tests, but in silver-stained gels all were shown to be deficient in O-antigen-containing B band. Investigation of serial isolates from a single patient revealed a pattern of antigenic variation. During the course of the infection, serotypeable isolates became nontypeable, and the O antigen was replaced with A band as the major LPS antigen. These results suggest that A-band LPS may be the major LPS antigen in nontypeable clinical isolates and a common antigen among other P. aeruginosa strains.

Agglutination Tests↗
PubMed1989

Clinical efficacy of ciprofloxacin in lower respiratory tract infections.

The sputum pharmacokinetics and clinical efficacy of ciprofloxacin in lower respiratory tract infections is reviewed. Following intravenous administration, ciprofloxacin penetrates rapidly into bronchial tissue; the elimination half life is between 3 and 4 h and a dose dependency is seen. Following oral intake, the time to reach maximal concentrations is approximately two hours and after a dose of 750 mg the concentration may reach 1.7 mg/l in patients without cystic fibrosis and range from 0.5 to 3.4 mg/l in cystic fibrosis patients. Coadministration of ciprofloxacin increases serum levels and decreases total body clearance of theophylline. In controlled comparative clinical trials, ciprofloxacin has been found to have similar clinical efficacy as amoxycillin, ampicillin, cefalexin, doxycycline, co-trimoxazole, imipenem-cilastatin and ceftazidime for the treatment of a range of lower respiratory tract infections. Ciprofloxacin has been found to be superior in clinical efficacy to cefaclor. Experimental animal models suggest a role for ciprofloxacin in infections caused by Legionella pneumophila and Mycoplasma pneumoniae. The clinical and bacteriological efficacy of ciprofloxacin is less pronounced in lung infections caused by Pseudomonas aeruginosa, but is comparable to the combination of beta-lactams and aminoglycosides. Development of resistance is frequently observed during ciprofloxacin treatment of Ps. aeruginosa. Because of the availability of other oral and effective agents, ciprofloxacin is not recommended for empirical treatment of community acquired lower respiratory infections, but should be reserved for infections caused by multiply resistant organisms.

Ciprofloxacin↗
PubMed1988

Use of immunoblot detection of serum antibodies in the diagnosis of chronic Pseudomonas aeruginosa lung infection in cystic fibrosis.

Antibodies to Pseudomonas aeruginosa were investigated in serum from cystic fibrosis (CF) patients by immunoblotting (Western blotting). The results were compared with determinations of precipitating antibodies in serum by crossed immune electrophoresis (CIE). The number of CIE precipitins is a sensitive and specific indication of infection and is used, with sputum bacteriology, to distinguish between colonisation and invasive lung infection. Immunoblotting was considerably more sensitive than CIE for detecting antibodies to P. aeruginosa. Paired serum samples from 64 CF patients, taken before a diagnosis of P. aeruginosa lung infection and immediately afterwards, showed a marked increase in the number of serum antibodies with the onset of infection. The intensity of the reaction, as shown by the density of blotted bands, was also increased. Laser scanning densitometry of immunoblots, and of photographic negatives taken from them, was used to quantify the increases. Differences in the number and intensity of blotted bands were highly significant between the two groups. The reproducibility of the method was good. An immunoblot assay may be a sensitive and useful method for routine diagnosis of early P. aeruginosa lung infection in CF.

Adult↗
PubMed1988

Increased IgG2 and IgG3 concentration is associated with advanced Pseudomonas aeruginosa infection and poor pulmonary function in cystic fibrosis.

The concentrations of IgG subclass immunoglobulins were determined by radial immunodiffusion in serum from 126 patients with cystic fibrosis (CF). The results were compared to values from age-matched healthy children and adults and correlated to patients age, duration of chronic Pseudomonas aeruginosa infection and lung function parameters. Fifty-two percent of the patients had an elevated concentration of at least one of the IgG subclasses; IgG1 28%, IgG2 16%, IgG3 18% and IgG4 48%. There was significant correlation between elevated serum levels of IgG2, and to a lesser extent IgG3, with decreased lung function (for FEV1; p = 0.0001, and p = 0.001 respectively) and high levels of antipseudomonas precipitins (p = 0.008, and p = 0.002). A similar correlation was not found for IgG1 and IgG4. IgG subclasses vary in their ability to promote phagocytosis and to activate complement and it is possible that individual differences in the IgG subclass pattern could explain the variable course of this disease.

Adolescent↗
PubMed1988

Excretion of urinary collagen metabolites correlates to severity of pulmonary disease in cystic fibrosis.

The urinary excretion of collagen metabolites (hydroxylysine, hydroxyproline and proline) was significantly increased in 10 patients with cystic fibrosis and chronic broncho-pulmonary Pseudomonas aeruginosa infection as compared with 14 age matched controls. The increase was significantly correlated to impaired pulmonary function (FVC and FEV1). The results indicate that urinary collagen metabolites reflect degradation of lung connective tissue and may be an indicator of the severity of pulmonary disease in cystic fibrosis. Parts of the excreted hydroxyproline may be degradation products of elastin.

Adolescent↗