Antibacterials. Synthesis and structure-activity studies of 3-aryl-2-oxooxazolidines. 1. The "B" group

The synthesis and structure/activity studies of the effect of varying the "B" group in a series of oxazolidinone antibacterials (I) are described. Two synthetic routes were used: (1) alkylation of aniline with glycidol followed by dialkyl carbonate heterocyclization to afford I (A = H, B = OH), whose arene ring was further elaborated by using electrophilic aromatic substitution methodology; (2) cycloaddition of substituted aryl isocyanates with epoxides to give A and B with a variety of values. I with B = OH or Br were converted to other "B" functionalities by using SN2 methodology. Antibacterial evaluation of compounds I with A = acetyl, isopropyl, methylthio, methylsulfinyl, methylsulfonyl, and sulfonamido and a variety of different "B" groups against Staphylococcus aureus and Enterococcus faecalis concluded that the compounds with B = aminoacyl, and particularly acetamido, were the most active of those examined in each A series, possessing MICs in the range of 0.5-4 micrograms/mL for the most active compounds described.     

Supervision, monitoring and evaluation of nationwide scale-up of antiretroviral therapy in Malawi

OBJECTIVE: To describe the supervision, monitoring and evaluation strategies used to assess the delivery of antiretroviral therapy during nationwide scale-up of treatment in Malawi. METHODS: In the first quarter of 2005, the HIV Unit of the Ministry of Health and its partners (the Lighthouse Clinic; Médecins Sans Frontières-Belgium, Thyolo district; and WHO's Country Office) undertook structured supervision and monitoring of all public sector health facilities in Malawi delivering antiretroviral therapy. FINDINGS: Data monitoring showed that by the end of 2004, there were 13,183 patients (5274 (40%) male, 12 527 (95%) adults) who had ever started antiretroviral therapy. Of patients who had ever started, 82% (10 761/13,183) were alive and taking antiretrovirals; 8% (1026/13,183) were dead; 8% (1039/13,183) had been lost to follow up; <1% (106/13,183) had stopped treatment; and 2% (251/13,183) had transferred to another facility. Of those alive and on antiretrovirals, 98% (7098/7258) were ambulatory; 85% (6174/7258) were fit to work; 10% (456/4687) had significant side effects; and, based on pill counts, 96% (6824/7114) had taken their treatment correctly. Mistakes in the registration and monitoring of patients were identified and corrected. Drug stocks were checked, and one potential drug stock-out was averted. As a result of the supervisory visits, by the end of March 2005 recruitment of patients to facilities scheduled to start delivering antiretroviral therapy had increased. CONCLUSION: This report demonstrates the importance of early supervision for sites that are starting to deliver antiretroviral therapy, and it shows the value of combining data collection with supervision. Making regular supervisory and monitoring visits to delivery sites are essential for tracking the national scale-up of delivery of antiretrovirals.     

Malawi's contribution to "3 by 5": achievements and challenges

PROBLEM: Many resource-poor countries have started scaling up antiretroviral therapy (ART). While reports from individual clinics point to successful implementation, there is limited information about progress in government institutions at a national level. APPROACH: Malawi started national ART scale-up in 2004 using a structured approach. There is a focus on one generic, fixed-dose combination treatment with stavudine, lamivudine and nevirapine. Treatment is delivered free of charge to eligible patients with HIV and there is a standardized system for recruiting patients, monthly follow-up, registration, monitoring and reporting of cases and outcomes. All treatment sites receive quarterly supervision and evaluation. LOCAL SETTING: In January 2004, there were nine public sector facilities delivering ART to an estimated 4 000 patients. By December 2005, there were 60 public sector facilities providing free ART to 37,840 patients using national standardized systems. Analysis of quarterly cohort treatment outcomes at 12 months showed 80% of patients were alive, 10% dead, 9% lost to follow-up and 1% had stopped treatment. LESSONS LEARNED: Achievements were the result of clear national ART guidelines, implementing partners working together, an intensive training schedule focused on clinical officers and nurses, a structured system of accrediting facilities for ART delivery, quarterly supervision and monitoring, and no stock-outs of antiretroviral drugs. The main challenges are to increase the numbers of children, pregnant women and patients with tuberculosis being started on ART, and to avert high early mortality and losses to follow-up. The capacity of the health sector to cope with escalating case loads and to scale up prevention alongside treatment will determine the future success of ART delivery in Malawi.     

Mechanisms of action of aminoglycoside antibiotics in eucaryotic protein synthesis.

Tetrahymena thermophila is a eucaryotic organism that is highly susceptible to growth inhibition by aminoglycoside antibiotics. Concentrations of paromomycin, gentamicin G418, and hygromycin B at 22, 10, and 17 microM, respectively, inhibited growth by 50%. A combination of in vitro and in vivo methods was used to determine the mechanisms of action of these aminoglycoside antibiotics on protein synthesis in T. thermophila. Analysis of polysome profiles from paromomycin- and gentamicin G418-treated cells showed clear, progressive depletions of polysomes concomitant with an inhibition of in vivo [14C] lysine incorporation. In vitro, paromomycin and gentamicin G418, which are disubstituted 2-deoxystreptamine-containing molecules, were not very effective inhibitors of either the translocation of peptidyl-tRNA or the elongation of nascent polypeptide chains on polysomes. In contrast, we found that the translocation of phe-tRNA on polyuridylate programmed ribosomes was susceptible to inhibition by paromomycin. We conclude that the primary inhibitory action of paromomycin and gentamicin G418 was at (i) an early stage of elongation after initiation, (ii) the initiation stage of translation, or (iii) a stage of translation before initiation. Hygromycin B, which is a monosubstituted 2-deoxystreptamine-containing aminoglycoside, potently inhibited the elongation of nascent chains during the translation of polysomes. In addition, the in vitro translation of polysomes from two hygromycin B-resistant mutants was resistant to the inhibition of elongation caused by hygromycin B.