Production of rhamnolipid biosurfactant by fed-batch culture of Pseudomonas aeruginosa using glucose as a sole carbon source.
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The pH-stat fed-batch culture of Pseudomonas aeruginosa YPJ-80 was done to produce a rhamnolipid biosurfactant. With glucose as the sole carbon source, the final concentrations of cells and rhamnolipid biosurfactant obtained in 25 h were 25 g cell dry weight/l and 4.4 g/l, respectively. (+info)
Oral low-molecular weight heparin and delivery agent prevents jugular venous thrombosis in the rat.
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PURPOSE: Sodium N-[10-(2-hydroxybenzoyl)amino]decanoate (SNAD) is a novel carrier that allows the gastrointestinal absorption of low-molecular weight heparin (LMWH). The purpose of this experiment was to evaluate oral LMWH with SNAD for the prevention of deep venous thrombosis. METHODS: Sixty Sprague-Dawley rats were equally assigned to five experimental groups: group 1 (control), oral saline solution; group 2, oral LMWH (15 mg/kg); group 3, oral SNAD (300 mg/kg); group 4, subcutaneous LMWH (5 mg/kg); and group 5, oral LMWH (15 mg/kg) and SNAD (300 mg/kg). After treatment, the jugular vein was isolated, occluded, and bathed in an ethanol and formalin solution for 2 minutes. Two hours later, the vessel was examined for patency, presence of thrombus, and thrombus weight. Serum measurement of anti-factor Xa activity was performed in a separate set of 30 rats, which were placed into the following four groups: group A, LMWH (5 mg/kg); group B, oral LMWH (15 mg/kg) and SNAD (300 mg/kg); group C, oral LMWH (15 mg/kg); and group D, SNAD (300 mg/kg). RESULTS: The animals that underwent oral LMWH/SNAD therapy had a statistically significant decrease in visible thrombi. The thrombus weight of the oral LMWH/SNAD group was significantly less than the weights of all other groups, except the subcutaneous LMWH group. Anti-factor Xa levels were significantly elevated in the LMWH/SNAD group. There was no statistically significant difference between the data for the oral LMWH/SNAD group and the subcutaneous LMWH group. CONCLUSION: The combination of oral LMWH and SNAD prevented deep venous thrombosis. The oral LMWH and SNAD therapy effected an increase in levels of anti-factor Xa. (+info)
Characterisation of three novel cationic lipids as liposomal complexes with DNA.
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Cationic lipids (CLs) are being increasingly exploited as transfection vectors for the delivery of DNA into eukaryotic cells. To obtain further insight to the complex formation and interactions between cationic liposomes and DNA, we characterised three novel cationic lipids, viz. bis[2-(11-phenoxyundecanoate)ethyl]-dimethylammonium bromide, N-hexadecyl-N- inverted question mark10-[O-(4-acetoxy)-phenylundecanoate]ethyl inverted question mark- dimethylammonium bromide, and bis[2-(11-butyloxyundecanoate)ethyl]dimethylammonium bromide. These lipids bear the same charged headgroup yet have different hydrophobic parts. Accordingly, we may anticipate their electrostatic interactions with DNA to be similar while differing in both thermal phase behaviour and physicochemical properties of their complexes with DNA. In keeping with the above all three lipids formed complexes with DNA as evidenced by light scattering, fluorescence spectroscopy and Langmuir film balance. Differential scanning calorimetry revealed very different phase behaviours for the binary mixtures of the three CLs with dimyristoylphosphatidylcholine and also provided evidence for DNA-induced lipid phase separation. These data were confirmed by compression isotherms and fluorescence microscopy of monolayers residing on an aqueous buffer, recorded both in the presence and absence of DNA. Importantly, binding to cationic liposomes appears to prevent thermal denaturation of DNA upon heating of the complexes. Likewise, renaturation of heat-treated DNA complexed with the cationic liposomes appears to be abolished as well. (+info)
Effects of structural changes on the tumor-promoting activity of phorbol myristate acetate on mouse skin.
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4a alpha-Phorbol-9,9a-didecanoate, 4a alpha-phorbol-9-myristate-9a-acetate, and phorbol-9-myristate-9a-acetate-3-aldehyde were tested for skin tumor-promoting activity by using 7,12-dimethylbenz(a)anthracene as the initiating agent. There were 30 female ICR/Ha mice/group, and tests were continued for 434 to 461 days. 4a alpha-Phorbol-9,9a-didecanoate and 4a alpha-phorbol-9-myristate-9a-acetate were devoid of tumor-promoting activity. Phorbol-9-myristate-9a-acetate-3-aldehyde resulted in 10 mice with papillomas, 2 of which also bore squamous carcinomas of the skin. The positive control group, in which phorbol myristate acetate was used as promoting agent, resulted in 30 mice bearing multiple papillomas and 15 bearing squamous carcinomas of the skin. The effects of structural and stereochemical changes on tumor-promoting activity suggest that a primary interaction of the phorbol ester series is binding at specific sites on the plasma membrane. (+info)
Polyphosphate kinase is essential for biofilm development, quorum sensing, and virulence of Pseudomonas aeruginosa.
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The human opportunistic pathogen Pseudomonas aeruginosa causes a variety of infections in immunocompromised hosts and in individuals with cystic fibrosis. A knockout mutation in the polyphosphate kinase (ppk) gene, encoding PPK responsible for the synthesis of inorganic polyphosphate from ATP, renders P. aeruginosa cells unable to form a thick and differentiated biofilm. The mutant is aberrant in quorum sensing and responses in that production of the quorum-sensing controlled virulence factors elastase and rhamnolipid are severely reduced. In a burned-mouse pathogenesis model, the virulence of the mutant is greatly reduced with severe defects in the colonization of mouse tissues. The conservation of PPK among many bacterial pathogens and its absence in eukaryotes suggest that PPK might be an attractive target for antimicrobial drugs. (+info)
New syntheses of the rice moth and stink bug pheromones by employing (2R, 6S)-7-acetoxy-2,6-dimethyl-1-heptanol as a building block.
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(2R, 6R, 10R)-6,10,14-Trimethyl-2-pentadecanol, the female pheromone of the rice moth (Corcyra cephalonica), methyl (2R, 6R, 10R)-2,6,10-trimethyltridecanoate, the male pheromone of the stink bug (Euschistus heros) were synthesized by employing (2R, 6S)-7-acetoxy-2,6-dimethyl-1-heptanol as the common chiral building block. (+info)
A rhamnolipid biosurfactant reduces cadmium toxicity during naphthalene biodegradation.
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A model cocontaminated system was developed to determine whether a metal-complexing biosurfactant, rhamnolipid, could reduce metal toxicity to allow enhanced organic biodegradation by a Burkholderia sp. isolated from soil. Rhamnolipid eliminated cadmium toxicity when added at a 10-fold greater concentration than cadmium (890 microM), reduced toxicity when added at an equimolar concentration (89 microM), and had no effect at a 10-fold smaller concentration (8.9 microM). The mechanism by which rhamnolipid reduces metal toxicity may involve a combination of rhamnolipid complexation of cadmium and rhamnolipid interaction with the cell surface to alter cadmium uptake. (+info)
Swarming of Pseudomonas aeruginosa is dependent on cell-to-cell signaling and requires flagella and pili.
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We describe swarming in Pseudomonas aeruginosa as a third mode of surface translocation in addition to the previously described swimming and twitching motilities. Swarming in P. aeruginosa is induced on semisolid surfaces (0.5 to 0.7% agar) under conditions of nitrogen limitation and in response to certain amino acids. Glutamate, aspartate, histidine, or proline, when provided as the sole source of nitrogen, induced swarming, while arginine, asparagine, and glutamine, among other amino acids, did not sustain swarming. Cells from the edge of the swarm were about twice as long as cells from the swarm center. In both instances, bacteria possessing two polar flagella were observed by light and electron microscopy. While a fliC mutant of P. aeruginosa displayed slightly diminished swarming, a pilR and a pilA mutant, both deficient in type IV pili, were unable to swarm. Furthermore, cells with mutations in the las cell-to-cell signaling system showed diminished swarming behavior, while rhl mutants were completely unable to swarm. Evidence is presented for rhamnolipids being the actual surfactant involved in swarming motility, which explains the involvement of the cell-to-cell signaling circuitry of P. aeruginosa in this type of surface motility. (+info)