ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Abstract Experimental dipole moments of some disubstituted 9-acridanones were compared to the vec... more Abstract Experimental dipole moments of some disubstituted 9-acridanones were compared to the vectorially and theoretically calculated values using CNDO/2 method. Results supported the existence of a presumed folding of these compounds with the prevalence of a quasi-equatorial conformation.
The potential of human plasma (HP) or serum (HS) as a replacement for fetal calf serum (FCS) was ... more The potential of human plasma (HP) or serum (HS) as a replacement for fetal calf serum (FCS) was evaluated in a liver infusion tryptose (LIT) medium for bulk cultivation of Leishmania donovani promastigotes. The promastigote yield with the LIT-FCS standard medium was 0.4–1.8×107 ml−1, and yields of 0.5–3.4×107 (P = 0.527) and 0.4–2.4×107 (P = 0.062) were recorded for two LIT medium variants containing HP or HS as supplement instead of FCS. Significantly, higher promastigote yields of 1.3–4.9×107 ml−1 were demonstrated when LIT medium was supplemented with HP of blood group O but not A, B, AB or equally pooled ABO (P = 0.007–0.020). Matching (P = 0.56) strong positive (1 : 10 2400 to ≥1 : 262 144 00) and weak negative (1 : 5–1 : 160) direct agglutination test (DAT) titres, respectively, were demonstrated in 24 visceral leishmaniasis (VL) and 45 non-VL sera for both standard LIT-FCS and alternative LIT-HP derived antigens. Our findings indicate strong potential for sustainable product...
... We are greatly indebted to Professor Gasim Badri, president of the university, Professor Abub... more ... We are greatly indebted to Professor Gasim Badri, president of the university, Professor Abubaker Uro, Mr. Mohamed el Mutasim and Mr. Hussam Ali Osman at ... 2003; 8:164-7. 7 ter Horst R, Tefera T, Assefa G, Ebrahim AZ, Davidson RN, Ritmeijer K. Field evaluation of rK39 test ...
Efflux mechanisms protect bacterial cells by pumping out toxic compounds and actively contribute ... more Efflux mechanisms protect bacterial cells by pumping out toxic compounds and actively contribute to bacterial multidrug resistance. Agents inhibiting efflux pumps are of interest for the control of multidrug-resistant bacterial infections. Herein we report the effects of new chloroquinoline derivatives that render resistant Enterobacter aerogenes isolates noticeably more susceptible to structurally unrelated antibiotics. In addition, some of these chloroquinolines increase the intracellular concentration of chloramphenicol. Some of the molecules tested in this work are able to inhibit the main efflux pump (AcrAB-TolC), which is involved in E. aerogenes antibiotic resistance.
This study was designed to test the hypothesis that lipophilic cationic drugs with only roughly s... more This study was designed to test the hypothesis that lipophilic cationic drugs with only roughly similar structures mediate the reversal of multidrug-resistance (MDR) by interacting with membrane phospholipids. The permeation properties of MDR-modulators and non-modulators were studied by quantifying their ability to induce the leakage of Sulphan blue through the membrane of negatively charged unilamellar liposomes. Of the 22 compounds under investigation, only those bearing a net positive electric charge per molecule (z) ≥0.2 induced dye leakage. All these efficient drugs are well-known MDR-modulators: calcium-channel blockers (propranolol, verapamil, diltiazem and dipyridamole), calmodulin antagonists (clomipramine and thioridazine) and antiparasitic agents (mepacrine, thioacridine derivatives and quinine). The non-modulators tested, including antineoplasic agents and steroids, did not induce any membrane permeation. The permeation process was a co-operative one (1.1 < Hill coefficient < 4.1) and the permeation doses inducing 50% dye leakage (PD50) were 1.9–11.2 mm. The permeation ability of the MDR-modulators (log(1/PD50)) increased significantly with octanol-buffer distributions per unit net electric charge ((logD)/z). The results provide evidence that a complex interplay occurs between the electric charge and the lipophilicity of the MDR-modulators when a dye leakage is induced through model membranes, and probably also when the MDR is reversed in leukaemic cells.
After several decades of continuously successful antibiotic therapy against bacterial infections,... more After several decades of continuously successful antibiotic therapy against bacterial infections, we are now facing a worrying prospect: the accelerated evolution of antibiotic resistance to important human pathogens and the scarcity of new anti-infective drug families under ...
Enterobacter aerogenes, one of the most frequently isolated nosocomial pathogens in France, is ex... more Enterobacter aerogenes, one of the most frequently isolated nosocomial pathogens in France, is exhibiting increasing multidrug resistance mechanisms associated with a change in membrane permeability. For drugs of the quinolone family, mutations in the target and active efflux play a prominent role in the resistance. We report here the effect of several pyridoquinoline derivatives that restore a noticeable fluoroquinolone accumulation to resistant strains that overexpress the MarA activator. Studies of the energy-dependent quinolone efflux indicate that the most efficient derivatives tested probably inhibit the resistance process by acting as substrate competitors on the pump extruding intracellular norfloxacin.
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Abstract Experimental dipole moments of some disubstituted 9-acridanones were compared to the vec... more Abstract Experimental dipole moments of some disubstituted 9-acridanones were compared to the vectorially and theoretically calculated values using CNDO/2 method. Results supported the existence of a presumed folding of these compounds with the prevalence of a quasi-equatorial conformation.
The potential of human plasma (HP) or serum (HS) as a replacement for fetal calf serum (FCS) was ... more The potential of human plasma (HP) or serum (HS) as a replacement for fetal calf serum (FCS) was evaluated in a liver infusion tryptose (LIT) medium for bulk cultivation of Leishmania donovani promastigotes. The promastigote yield with the LIT-FCS standard medium was 0.4–1.8×107 ml−1, and yields of 0.5–3.4×107 (P = 0.527) and 0.4–2.4×107 (P = 0.062) were recorded for two LIT medium variants containing HP or HS as supplement instead of FCS. Significantly, higher promastigote yields of 1.3–4.9×107 ml−1 were demonstrated when LIT medium was supplemented with HP of blood group O but not A, B, AB or equally pooled ABO (P = 0.007–0.020). Matching (P = 0.56) strong positive (1 : 10 2400 to ≥1 : 262 144 00) and weak negative (1 : 5–1 : 160) direct agglutination test (DAT) titres, respectively, were demonstrated in 24 visceral leishmaniasis (VL) and 45 non-VL sera for both standard LIT-FCS and alternative LIT-HP derived antigens. Our findings indicate strong potential for sustainable product...
... We are greatly indebted to Professor Gasim Badri, president of the university, Professor Abub... more ... We are greatly indebted to Professor Gasim Badri, president of the university, Professor Abubaker Uro, Mr. Mohamed el Mutasim and Mr. Hussam Ali Osman at ... 2003; 8:164-7. 7 ter Horst R, Tefera T, Assefa G, Ebrahim AZ, Davidson RN, Ritmeijer K. Field evaluation of rK39 test ...
Efflux mechanisms protect bacterial cells by pumping out toxic compounds and actively contribute ... more Efflux mechanisms protect bacterial cells by pumping out toxic compounds and actively contribute to bacterial multidrug resistance. Agents inhibiting efflux pumps are of interest for the control of multidrug-resistant bacterial infections. Herein we report the effects of new chloroquinoline derivatives that render resistant Enterobacter aerogenes isolates noticeably more susceptible to structurally unrelated antibiotics. In addition, some of these chloroquinolines increase the intracellular concentration of chloramphenicol. Some of the molecules tested in this work are able to inhibit the main efflux pump (AcrAB-TolC), which is involved in E. aerogenes antibiotic resistance.
This study was designed to test the hypothesis that lipophilic cationic drugs with only roughly s... more This study was designed to test the hypothesis that lipophilic cationic drugs with only roughly similar structures mediate the reversal of multidrug-resistance (MDR) by interacting with membrane phospholipids. The permeation properties of MDR-modulators and non-modulators were studied by quantifying their ability to induce the leakage of Sulphan blue through the membrane of negatively charged unilamellar liposomes. Of the 22 compounds under investigation, only those bearing a net positive electric charge per molecule (z) ≥0.2 induced dye leakage. All these efficient drugs are well-known MDR-modulators: calcium-channel blockers (propranolol, verapamil, diltiazem and dipyridamole), calmodulin antagonists (clomipramine and thioridazine) and antiparasitic agents (mepacrine, thioacridine derivatives and quinine). The non-modulators tested, including antineoplasic agents and steroids, did not induce any membrane permeation. The permeation process was a co-operative one (1.1 < Hill coefficient < 4.1) and the permeation doses inducing 50% dye leakage (PD50) were 1.9–11.2 mm. The permeation ability of the MDR-modulators (log(1/PD50)) increased significantly with octanol-buffer distributions per unit net electric charge ((logD)/z). The results provide evidence that a complex interplay occurs between the electric charge and the lipophilicity of the MDR-modulators when a dye leakage is induced through model membranes, and probably also when the MDR is reversed in leukaemic cells.
After several decades of continuously successful antibiotic therapy against bacterial infections,... more After several decades of continuously successful antibiotic therapy against bacterial infections, we are now facing a worrying prospect: the accelerated evolution of antibiotic resistance to important human pathogens and the scarcity of new anti-infective drug families under ...
Enterobacter aerogenes, one of the most frequently isolated nosocomial pathogens in France, is ex... more Enterobacter aerogenes, one of the most frequently isolated nosocomial pathogens in France, is exhibiting increasing multidrug resistance mechanisms associated with a change in membrane permeability. For drugs of the quinolone family, mutations in the target and active efflux play a prominent role in the resistance. We report here the effect of several pyridoquinoline derivatives that restore a noticeable fluoroquinolone accumulation to resistant strains that overexpress the MarA activator. Studies of the energy-dependent quinolone efflux indicate that the most efficient derivatives tested probably inhibit the resistance process by acting as substrate competitors on the pump extruding intracellular norfloxacin.
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