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L Koo

Publications and source records attributed to L Koo.

11 recordsLinked to original sources
PubMed1991

Adhesion of Pseudomonas aeruginosa pilin-deficient mutants to mucin.

Attachment of Pseudomonas aeruginosa to epithelial cells or tracheobronchial mucin is mediated by surface adhesins. Pili, composed of monomeric pilin subunits, make up one such class of adhesins. The formation of pili and flagella in P. aeruginosa is under the control of the alternative sigma factor rpoN. Isogenic mutant strains with insertionally inactivated rpoN genes were constructed with strains PAK, 1244, and CF613 and were tested for their ability to adhere to respiratory mucin. All rpoN mutants showed significant reduction of adherence to mucin relative to that of their wild-type parents. In contrast, the adherence of pilin structural gene mutants was similar to the adherence of wild types. These results provide suggestive evidence that P. aeruginosa also binds to mucin via adhesins that are distinct from pilin and are still under the genetic control of rpoN. Unlike the laboratory strain PAK, the clinical strains 1244 and CF613 are capable of agglutinating erythrocytes. The rpoN mutation had a minimal effect on the interaction of bacteria with erythrocytes, indicating that the transcription of a gene(s) specifying the agglutination phenomenon does not utilize rpoN. These findings collectively indicate the existence of several classes of adhesins on the surface of P. aeruginosa that may play an important role in colonization of the human respiratory tract.

Bacterial Adhesion↗
PubMed1989

Differences in adhesion of Pseudomonas aeruginosa to mucin glycopeptides from sputa of patients with cystic fibrosis and chronic bronchitis.

Pseudomonas aeruginosa is the most prominent colonizer of the respiratory tract of patients with cystic fibrosis, but it is not known why this occurs. P. aeruginosa adheres to mucins from normal individuals, but mucins from cystic fibrosis patients have not been studied. To compare adhesion to mucins from cystic fibrosis with other mucins, we prepared highly glycosylated mucin glycopeptides from cystic fibrosis and chronic bronchitis patients by ion-exchange and gel-filtration chromatography and measured the adhesion of P. aeruginosa 1244 to these glycopeptides. We found (i) that the most mucinlike glycopeptides from P. aeruginosa-infected cystic fibrosis sputa showed less bacterial adhesion than did the corresponding bronchitis samples, (ii) that the most adhesive activity in cystic fibrosis samples came from a fraction that contains O and N glycopeptides and may be in part a degradation product of P. aeruginosa infection, and (iii) that highly glycosylated glycopeptides of the most acidic species (sialylated and sulfated) showed no adhesion at all. A single cystic fibrosis sample not infected by P. aeruginosa showed better binding in the adhesion-positive fractions than did the infected sputa. These studies suggest that cystic fibrosis mucins may be altered after infection is established, resulting in less binding to some fragments. However, since the clinical picture shows heavy mucus colonization, other receptors, such as cellular glycolipids which have been shed into mucus, may be contributing to this colonization.

Bacterial Adhesion↗
PubMed1980

Earlobe crease.

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Black People↗
PubMed1976

Correlations between substituent parameters of 4-substituted benzoic acids and their in vitro dissolution and partitioning.

The in vitro dissolution and partitioning of some 4-substituted benzoic acids from nondisintegrating disks was investigated using a water-octanol system. The rates of appearance of benzoic acids in the aqueous phase differed from the rates of appearance in octanol, probably due to back-transfer from the octanol phase. The suitability of the procedure for investigating the influence of molecular modification on in vitro dissolution and partitioning is considered. Correlations among the rates of appearance in octanol, the rates of appearance in an aqueous phase, and substituent parameters of benzoic acids were investigated. The best statistical fit was obtained using molecular orbital substituent indexes.

Benzoates↗
PubMed1975

Interaction of substituted benzoic acids with polysorbate 20 micelles.

Equilibrium solubilities of a series of substituted benzoic acids in different concentrations of polysorbate 20 at controlled pH were measured. The maintenance of pH was achieved using a pH-stat assembly. A linear relationship was found between the amount of benzoic acid solubilized and surfactant concentration. As solubilizate polarity increased, the amount solubilized also increased. Solubility data were analyzed, and the interaction between solubilizate molecules and micelles was calculated in terms of partition coefficients of ionized and unionized molecules between aqueous and micellar phases. A linear relationship between pi values (log partition coefficients) of functional groups and aqueous-micellar partition coefficient was found.

Benzoates↗
PubMed1975

[Not Available].

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China↗