In vitro antimycobacterial activities of a new quinolone, balofloxacin

Balofloxacin (BLFX), a newly developed fluoroquinolone, was studied for its in vitro antimycobacterial activity by the agar dilution method with 7H11 agar medium. The MIC90s were as follows: 0.39 microgram/ml for M. tuberculosis, > 50 micrograms/ml for M. avium, > 50 micrograms/ml for M. intracellulare, 0.39 microgram/ml for M. kansasii, 0.39 microgram/ml for M. fortuitum, > 50 micrograms/ml for M. abscessus, and 50 micrograms/ml for M. chelonae. The antimycobacterial activity of BLFX was comparable or slightly inferior to that of levofloxacin (LVFX). Considering the present findings and pharmacokinetics of BFLX, it appears that BFLX may achieve favorable outcome in the treatment of patients with infection due to M. tuberculosis, M. kansasii, or M. fortuitum similar to that of ofloxacin or LVFX.     

Determination of in vitro susceptibility of mycobacteria to ansamycin

The in vitro susceptibility of different mycobacterial species to ansamycin (LM427) in concentrations of 2.0, 1.0, 0.5, and 0.2 micrograms/ml was determined by the agar dilution method. For those strains of M. tuberculosis and M. avium complex tested, susceptibility to ansamycin was compared with susceptibility to rifampin. All M. tuberculosis strains susceptible to rifampin were susceptible to ansamycin; the strains that were highly resistant to rifampin also were resistant to ansamycin. The majority of M. avium complex strains were "naturally" resistant to rifampin (1.0 micrograms/ml and higher), but only approximately 13% of them were resistant to ansamycin in a concentration of 1.0 microgram/ml. The cross-resistance in M. avium strains was made apparent only by comparing patterns of resistance to low concentrations of ansamycin (0.5 microgram/ml) with patterns of resistance to higher concentrations of rifampin (5.0 and 10.0 micrograms/ml).     

以脂肪酸合成酶FabH为靶标的化合物体外抗结核作用的初步研究

目的研究结核分枝杆菌脂肪酸合成酶FabH为靶标的化合物的体外抗结核活性,研制新的高效、安全的抗结核药物。方法以平板滤纸法测定化合物对草分枝杆菌的抑菌圈,以试管抑菌法检测化合物对结核分枝杆菌药物敏感株和耐多药分离株的抑制作用。结果18种化合物在500μmol/L浓度时对草分枝杆菌的抑菌圈为1.82.4 cm,其中7种化合物在250μmol/L和125μmol/L浓度时对草分枝杆菌的抑菌圈为1.52.2 cm。结核分枝杆菌H₃₇Rv标准株在分别含3mmol/L的18种化合物的培养基上培养2周时,绝大多数含化合物培养基上未见细菌生长;培养4周时,No.115、No.131、No.128、No.129、No.137化合物的抑菌作用较明显。结核分枝杆菌耐多药分离株HB240在分别含3mmol/L的11种化合物的培养基上培养2周和4周时,No.115化合物均显示明显的抑菌作用。结论以脂肪酸合成酶FabH为靶标的大多数化合物在体外都具有不同程度的抗结核活性,尤其是No.115化合物对草分枝杆菌、结核分枝杆菌敏感株和耐药株都具有明显的抑制作用。     

以脂肪酸合成酶FabH为靶标的化合物体外抗结核作用的初步研究

目的研究结核分枝杆菌脂肪酸合成酶FabH为靶标的化合物的体外抗结核活性，研制新的高效、安全的抗结核药物。方法以平板滤纸法测定化合物对草分枝杆菌的抑菌圈，以试管抑菌法检测化合物对结核分枝杆菌药物敏感株和耐多药分离株的抑制作用。结果18种化合物在500μmol／L浓度时对草分枝杆菌的抑菌圈为1．8～2．4cm，其中7种化合物在250μmol／L和125μmol／L浓度时对草分枝杆菌的抑菌圈为1．5～2．2cm。结核分枝杆菌H37Rv标准株在分别含3mmol／L的18种化合物的培养基上培养2周时，绝大多数含化合物培养基上未见细菌生长；培养4周时，No．115、No．131、No．128、No．129、No．137化合物的抑菌作用较明显。结核分枝杆菌耐多药分离株HB240在分别含3mmol／L的11种化合物的培养基上培养2周和4周时，No．115化合物均显示明显的抑菌作用。结论以脂肪酸合成酶FabH为靶标的大多数化合物在体外都具有不同程度的抗结核活性，尤其是No．115化合物对草分枝杆菌、结核分枝杆菌敏感株和耐药株都具有明显的抑制作用。     

Comparison of in vitro and in vivo antimalarial activities of 9-phenanthrenecarbinols

Analysis of the antimalarial activity of a selected series of 17 9-phenanthrenecarbinols against cultured strains of Plasmodium falciparum and against P. berghei in mice following oral administration indicated that the rankings of activities within the series were influenced by substituents on the 9-carbinol and the route of administration. Compounds with alkylamino-alkyl groups were ranked as most active by an in vitro screening system which assayed activity against chloroquine-sensitive and chloroquine-resistant strains of cultured P. falciparum by the inhibition of uptake of radiolabelled hypoxanthine. There were few differences in ranking of activities between the two strains. Although there was a significant difference between activities of an erythro- and a threo-racemate, activities of the four optical isomers of this compound were comparable. Among the series, compounds with a 2-piperidyl substituent on the 9-carbinol were ranked most active by the oral route of administration as assayed by the cure rates of mice infected with P. berghei. Correlation of these observations with previously published data on the activity of these compounds against P. falciparum in Owl monkeys and P. berghei in mice following subcutaneous administration suggested that neither species of host nor strains of parasite significantly influenced the ranking of activities of this class of compound.     

Comparison of inhibin immunological and in vitro biological activities in human serum

A comparison of serum inhibin levels in men and women was undertaken using a sensitive sheep pituitary cell in vitro bioassay and a newly developed heterologous RIA. The RIA was based on an antiserum raised to bovine 31K inhibin using [125I]31K inhibin as tracer. Bovine inhibin alpha- and beta-subunits, bovine activin-A, transforming growth factor-beta, and Mullerian inhibitory substance did not cross-react in the RIA. In both assays, dilutions of serum gave response lines parallel to that of the partially purified human follicular fluid inhibin preparation used as standard. Negligible levels of both bio (B)- and immuno (I) activities were found in serum from women with premature ovarian failure or castrated men. In ovulation-induced cycles, serum B inhibin levels increased progressively from the early to the late follicular phase and remained at the late follicular phase level during the early and midluteal phases. Serum I inhibin levels also rose during the follicular phase, but declined during the early luteal phase before increasing again in the midluteal phase. As a consequence, inhibin B:I ratios varied during the treatment cycle, with high ratios in early follicular (2.86) and early luteal (2.25) phases and a low ratio in the midluteal phase (1.09). Similar changes in serum B:I ratios also occurred during the midcycle and midluteal phases of normal cycles. The B:I ratio was lower (0.35) in normal men. We conclude that the largely similar pattern of inhibin biological and immunological activities in serum obtained during a variety of physiological conditions support the validity of the RIA procedure, and the B:I ratio of serum inhibin varies during the follicular and luteal phases of the cycle and is low in men. Potential reasons for these changes in B:I ratio include the presence of interfering substances in either the bioassay or the RIA, the presence of inhibin isoforms, and/or modulation of secreted forms by sex steroids.     

Dynamic aspects of the in vitro chemotherapeutic activity of ansamycin (rifabutine) on mycobacterium intracellulare

The in vitro action of ansamycin against Mycobacterium intracellulare was studied using continuous, dynamic (a rapidly falling off concentration simulating that existing in vivo in humans), and pulsed exposures. Ansamycin at a concentration of 5 micrograms/ml showed bactericidal activity starting from as early as 3 days after constant exposure. In the dynamic model with the drug present in bactericidal concentration for only 2 h a day, bactericidal activity was demonstrated. With pulsed exposure, a minimal period of 72 to 96 h is necessary for effective inhibitory action.     

Comparative in vitro and in vivo activity of rifabutin and rifampicin against Mycobacterium avium complex

In vitro antimicrobial activity of rifabutin and rifampicin against various mycobacteria, including the Mycobacterium avium complex, was evaluated by the agar dilution method, using 7H10 agar medium. The activity of rifabutin based on MIC50 and MIC90 was higher than that of rifampicin, against all the acid-fast organisms tested. Microbicidal activity of rifabutin against the M. avium complex phagocytosed in mouse peritoneal or alveolar macrophages was greater than that of rifampicin. Both rifabutin and rifampicin had therapeutic effects against murine infections induced by M. avium complex. Rifabutin was somewhat more effective than rifampicin in mice.