ABSTRACT
In a chemical mutagenesis screen, we identified two zebrafish mutants that possessed small pupils. Genetic complementation revealed these two lines are due to mutations in different genes. The phenotypes of the two mutants were characterized using histologic, immunohistochemical, and tissue transplantation techniques. The arrested lens (arl) mutant exhibits a small eye and pupil phenotype at 48 hr postfertilization (hpf) and lacks any histologically identifiable lens structures by 5 days postfertilization (dpf). In contrast, the disrupted lens (dsl) mutants are phenotypically normal until 5 dpf, and then undergo lens disorganization and cell degeneration that is apparent by 7 dpf. Histology reveals the arl mutant terminates lens cell differentiation by 48 hpf, whereas the dsl lens exhibits a defective lens epithelial cell population at 5 dpf. Lens transplantation experiments demonstrate both mutations are autonomous to the lens tissue. Immunohistochemistry reveals the retinal cells may suffer subtle effects, possibly due to the lens abnormalities.
Subject(s)
Epithelial Cells/cytology , Epithelial Cells/pathology , Lens, Crystalline/embryology , Mutation/physiology , Zebrafish/embryology , Animals , Cell Death , Cell Differentiation , Embryo, Nonmammalian/cytology , Embryo, Nonmammalian/metabolism , Homeodomain Proteins/metabolism , Immunohistochemistry , Lens, Crystalline/transplantation , Male , Phenotype , Retina/cytology , Retina/embryology , Tumor Suppressor ProteinsABSTRACT
This paper describes the discovery of alpha-trifluoroketoacetamides as potent antibacterial agents against Gram-positive organisms. The initial SAR indicates that the aryl ethyl side chain is essential in maintaining antibacterial activity. The SAR observations have been utilized to design a bioisostere for the alpha-trifluoroketoacetamide with good activity against Gram-positive organisms.
Subject(s)
Acetamides/pharmacology , Anti-Bacterial Agents/pharmacology , Fluoroacetates , Gram-Positive Bacteria/drug effects , Acetamides/chemical synthesis , Anti-Bacterial Agents/chemical synthesis , Gram-Negative Bacteria/drug effects , Microbial Sensitivity Tests , Molecular Structure , Structure-Activity Relationship , Trifluoroacetic Acid/chemistryABSTRACT
Important resistance patterns in Gram-negative pathogens include active efflux of antibiotics out of the cell via a cellular pump and decreased membrane permeability. A 3-arylpiperidine derivative (1) has been identified by high-throughput assay as a potentiator with an IC(50) approximately 90 microM. This report details the evaluation of the tether length, aryl substitution and the importance of the fluorine on antibiotic accumulation. Evaluation of various tether lengths demonstrated that the two-carbon tethered analogues are optimal. Removal of the fluorine has a modest effect on antibiotic accumulation and the defluorinated analogue 17 is equally potent to the original lead 1.
Subject(s)
Anti-Bacterial Agents/pharmacology , Escherichia coli/drug effects , Gram-Negative Bacteria/drug effects , Piperidines/pharmacology , Staphylococcus aureus/drug effects , Anti-Bacterial Agents/chemical synthesis , Biological Transport, Active/physiology , Drug Resistance , Drug Synergism , Fluorine/chemistry , Gram-Negative Bacteria/pathogenicity , Inhibitory Concentration 50 , Microbial Sensitivity Tests/standards , Permeability , Piperidines/chemical synthesisABSTRACT
Peptidyl deformylase (PDF) is a metallo protease that catalyzes the removal of a formyl group from the N-termini of prokaryotic prepared polypeptides, an essential step in bacterial protein synthesis. Screening of our compound collection using Staphylococcus aureus PDF afforded a very potent inhibitor with an IC(50) in the low nanomolar range. Unfortunately, the compound that contains a hydroxamic acid did not exhibit antibacterial activity (MIC). In order to address the lack of activity in the MIC assay and to determine what portion of the molecule was responsible for binding to PDF, we prepared several analogues. This paper describes our findings that the hydroxamic acid functionality found in 1 is mainly responsible for the high affinity to PDF. In addition, we identified an alternative class of PDF inhibitors, the N-hydroxy urea 18, which has both PDF and antibacterial activity.
Subject(s)
Amidohydrolases , Aminopeptidases/antagonists & inhibitors , Anti-Bacterial Agents/pharmacology , Hydroxamic Acids/pharmacology , Staphylococcus aureus/drug effects , Aminopeptidases/chemistry , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Hydroxamic Acids/chemical synthesis , Hydroxamic Acids/chemistry , Metalloendopeptidases/antagonists & inhibitors , Microbial Sensitivity Tests , Models, Molecular , Protein Conformation , Staphylococcus aureus/enzymology , Structure-Activity RelationshipABSTRACT
An open, non-comparative study of 10 weeks' duration was conducted in general practice to assess the safety of amlodipine in patients with mild to moderate hypertension. Of the 5352 patients entering the study, 5135 received amlodipine; 4621 patients (90%) with a mean age of 58.2 years completed the study. Normalisation of blood pressure was achieved in over 80% of patients with a mean reduction of 21/15 mmHg. The mean final dose of amlodipine was 6.8 mg/day. Adverse experiences possibly related to amlodipine were reported by 19.3% of patients, and overall adverse events led to withdrawal in 6.7% of patients. The most common reported side-effect was oedema. The frequency of headache was almost identical in older and younger patients and oedema, flushing and dizziness were seen only slightly more often in elderly patients. Ninety per cent of patients were considered by their GP to have shown excellent or good toleration of therapy. Over 85% of patients elected to continue on amlodipine therapy after completion of the study.