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P V Liu

Publications and source records attributed to P V Liu.

At least 19 recordsLinked to original sources
PubMed1990

Three new major somatic antigens of Pseudomonas aeruginosa.

Three new major somatic antigens of Pseudomonas aeruginosa have been described and added to the 17 existing groups in the International Antigenic Typing System (P. V. Liu, H. Matsumoto, H. Kusama, and T. Bergan, Int. J. Syst. Bacteriol. 33:256-264, 1983). These newly recognized antigens are present in some strains of P. aeruginosa that have been used as type strains of various typing schemata but have not been recognized because of cross-reactions of these strains with antisera of other serogroups with minor antigens. The lists of corresponding serogroups of various serotyping schemata have been revised accordingly.

Antigens, Bacterial↗
PubMed1988

The reason for loss of agglutinability of Pseudomonas aeruginosa cells heated to 60 degrees C.

The loss of agglutinability of live Pseudomonas aeruginosa cells by mild heating to 60 to 80 degrees C is due to denaturation of surface slime, which can no longer combine with antibodies but is still attached to the cell surface and thus prevents access of antibodies to the cell wall. Prolonged boiling or autoclaving would not only denature the slime but also detach it from cell surface and thus make the cells accessible to antibodies directed to cell wall antigens. Heated cells are, however, no longer agglutinable by antibodies directed to slime antigens. After prolonged boiling or autoclaving, a large amount of polysaccharides appeared in the supernatant, and concomitantly, total cell volume as measured by turbidity of the cell suspension was significantly reduced.

Agglutination↗
PubMed1988

Method for in vitro conversion of rough strains of Pseudomonas aeruginosa to smooth strains.

Rough and serologically nontypable strains of Pseudomonas aeruginosa were found to become smooth and typable in vitro when they were maintained in a soft agar containing 0.5% peptone in distilled water and the dried out agar cultures were replenished monthly with a similar peptone solution in distilled water. After about a year, all of the nine rough strains of P. aeruginosa maintained this way became smooth and typable, and their pigmentations also changed significantly. Some melanogenic strains became fluorescine producers, and some weakly chromogenic strains became strong producers of fluorescine and pyocyanin.

Culture Media↗
PubMed1987

Comparison of the Chinese schema and the International Antigenic Typing System for serotyping Pseudomonas aeruginosa.

Twelve strains of Pseudomonas aeruginosa representing 12 serogroups in the serogrouping schema used in the People's Republic of China were compared with serogroups in the International Antigenic Typing System (IATS). The first eight groups originated in the People's Republic of China, and group II appears to have a new major antigen that is not found in the IATS. Groups I, III, IV, V, VI, VII, and VIII correspond to groups 11, 6, 9, 4, 8, 3, and 1, respectively, of the IATS. Groups IX, X, XI, and XII are immunotypes 3, 4, 5, and 1, respectively, of Fisher et al. (M. W. Fisher, H. B. Devlin, and F. J. Gnabasik, J. Bacteriol., 98:835-836, 1969); they exhibited a wide range of serological cross-reactions but correspond mainly to IATS groups 2, 3, 10, and 6, respectively.

Agglutination Tests↗
PubMed1978

Biological activities of pyochelins: iron-chelating agents of Pseudomonas aeruginosa.

Strains of Pseudomonas aeruginosa able to grow readily in serum (serum resistant) produce siderophores in large quantity, enabling them to extract iron from transferrins. The term pyochelin has been proposed for this group of compounds. Pyochelin extractable with ethyl acetate and designated pyochelin A appears to be a mixture of catechols and other phenolates. The structures of water-soluble siderophores, designated pyochelin B, have not been determined. Pyochelins enabled growth in serum of strains of serum-sensitive P. aeruginosa and other gram-negative bacilli. Serum-resistant strains of P. aeruginosa tended to be more virulent than equally toxigenic strains of the serum-sensitive group. However, incorporation of pyochelins into the inocula of serum-sensitive strains could reduce, rather than enhance, their virulence. Utilization of pyochelins by serum-sensitive strains of P. aeruginosa rendered some of these organisms resistant to pyocins which were otherwise lethal to them.

Bacteria↗
PubMed1977

Mechanism of action of Pseudomonas aeruginosa exotoxin Aiadenosine diphosphate-ribosylation of mammalian elongation factor 2 in vitro and in vivo.

Previous studies showed that Pseudomonas aeruginosa exotoxin A (PA toxin) catalyzes nicotinamide adenine dinucleotide (NAD)-dependent inhibition of protein synthesis in a rabbit reticulocyte lysate and transfer of radioactivity from [14C]adenine-labeled NAD to a protein having the same molecular weight as elongation factor 2 (EF-2) (B.H. Iglewski and D. Kabat, 1975). Such an inhibited protein-synthesizing lysate was restored to activity by addition of a protein from normal mouse liver which co-purifies with EF-2. In addition, EF-2 activity was almost totally absent in livers of mice which had been injected 24 h earlier with PA toxin. On the contrary, EF-2 concentrations were only partially reduced in other organs and were normal in brains of intoxicated mice. Studies using NAD labeled in various positions show that PA toxin, like fragment A of diphtheria toxin, catalyzes transfer of the adenosine 5'-diphosphate-ribosyl moiety of NAD. Furthermore, reversal occurred when the modified protein was incubated with excess concentrations of PA toxin and nicotinamide, and NAD was identified as a product of the reverse reaction. The protein modification catalyzed either by PA toxin or by fragment A of diphtheria toxin could be reversed by incubation with other toxin. These results support the proposal that these two toxins adenosine 5'-diphosphate-ribosylate and same amino acid of EF-2 in a stereochemically identical fashion. Furthermore, PA toxin inactivates EF-2 in intoxicated mice to an extent which would ultimately result in death.

Adenosine Diphosphate↗
PubMed1976

Temperature-dependent inactivating factor of Pseudomonas aeruginosa exotoxin A.

The adenosine diphosphate ribosyl transferase activity of Pseudomonas aeruginosa exotoxin A(PA toxin) was found to be rapidly destroyed by heating at 45 to 60C but not by heating at 70 to 90C (for at least 30 min). This phenomenon has been previously described for other bacterial toxins (staphylococcal alpha-toxin and Vibrio parahaemolyticus hemolysin) and is termed an Arrhenius effect. In contrast, the Arrhenius effect was not seen when the PA toxin was heat-treated as above and tested for cell toxicity or mouse lethality. Although the PA toxin treated at 70C for 30 min retained a significant proportion (is greater than 70%) of its adenosine diphosphate ribosyl transferase activity, the cell toxicity and mouse lethality of the toxin were virtually abolished. A temperature-dependent inactivating factor that has proteolytic activity and is co-purified with the PA toxin was shown to be responsible for the Arrhenius effect. PA toxin separated from the factor by conventional disc gel electrophoresis or PA toxin preparations lacking the factor did not show the Arrhenius effect.

ADP Ribose Transferases↗
PubMed1969

Inhibition of protease production of various bacteria by ammonium salts: its effect on toxin production and virulence.

Production of protease by many bacteria was found to be inhibited by ammonium salts, and the enzyme production was more sensitive to the salts than was growth of the organisms. Inhibition of protease production by some pathogenic bacteria may result in the recognition of an exotoxin which otherwise would have been digested by the protease. In the case of Pseudomonas aeruginosa, qualitatively different toxicities could be demonstrated in the culture fluids, depending on the presence or absence of protease in such a fluid. The toxicity of the culture in the presence of a high titer of protease may be due primarily to the protease, whereas the toxicity exhibited in the absence of protease could be due to proteinacious exotoxin. Producers of high titers of protease tended to be less virulent in vivo than producers of low titers of the enzyme, which exert their toxicities by a separate exotoxin.

Aeromonas↗
PubMed1967

Improved assay method for phospholipase C.

A lecithin sol dispersed with deoxycholate was found to be attacked by phospholipase C in the presence of calcium ion more rapidly than were any other lecithin sols. The inorganic phosphate could be released quantitatively from the acid soluble phosphate liberated from lecithin by an excess amount of alkaline phosphatase present in phospholipase C reaction mixture. A simple and accurate assay method for phospholipase C was developed with the sol and the alkaline phosphatase.

Alkaline Phosphatase↗