Solution structure of a brodimoprim analogue in its complex with Lactobacillus casei dihydrofolate reductase

Two-dimensional (2D) double-quantum-filtered correlation spectroscopy (DQF-COSY), total correlation spectroscopy (TOCSY), nuclear Overhauser effect spectroscopy (NOESY), and rotating-frame NOESY (ROESY) spectra were used to assign essentially all the protons in a 1:1 complex of Lactobacillus casei dihydrofolate reductase formed with an analogue of the antibacterial drug brodimoprim [2,4-diamino-5-(3',5'-dimethoxy-4'-bromobenzyl)pyrimidine]. The analogue has a 4,6-dicarboxylic acid side chain substituted on the 3'-O position designed to interact with the Arg 57 and His 28 residues in L. casei dihydrofolate reductase; it binds a factor of 10(3) more tightly to the enzyme than does the parent compound. Thirty-eight intermolecular and 11 intramolecular NOEs were measured involving the bound brodimoprim-4,6-dicarboxylic acid analogue. These provided the distance constraints used in conjunction with an energy minimization and simulated annealing protocol (using Discover from Biosym Ltd.) to dock the brodimoprim analogue into dihydrofolate reductase. In calculations where side chains and backbone fragments for binding-site residues were allowed flexibility, 90% of the 40 calculated structures had reasonable covalent geometry and none of them had NOE distance violations of greater than 0.36 A. The conformations of the aromatic rings in the bound ligand were well-defined in all the structures, with torsion angles tau 1 = -153 degrees +/- 4 degrees (C4-C5-C7-C1') and tau 2 = 53 degrees +/- 4 degrees (C5-C7-C1'-C2'): the aromatic rings of the ligand occupied essentially the same space in all the calculated structures (root mean square deviation value 1.83 A). Inclusion of the electrostatic interactions into the energy minimizations indicated that structures in which the 4,6-dicarboxylate group of the ligand interacts with the side chains of Arg 57 and His 28 are of low energy. Significant differences in side-chain and backbone conformations were detected between binding-site residues in the enzyme complexes with the brodimorpim analogue and methotrexate.     

Treatment of solitary subconjunctival cysts of filtration pad after fistulizing surgery of glaucoma

The clinical picture and cytostatic treatment of solitary subconjunctival cysts of filtration pad after fistula-forming antiglaucoma surgery are described. Twenty-seven eyes with hypertension which developed as a result of subconjunctival cysts formed in the early postoperative period in 7% of patients operated on for open-angle glaucoma. Probable mechanisms of the pathogenesis of the formation of solitary cysts are discussed and 3-staged therapy proposed, including beta-blockers, perforation of the cyst wall by YAG laser, and, in 10% of cases with rigid cysts, microsurgical revision of filtration pad.     

The morbidity indices of subjects with incorporated radioactive iodine

With the purpose of detecting long-term somatic effects of incorporated iodine, an analysis was performed of health disorders in those subjects (n = 1040) who received 131 I in therapeutic dosages 25 to 30 years ago. Discordances in pituitary-thyroid- and pituitary-adrenal axes were found to result in excessive metabolic-degenerative and vegetovascular type morbidity rates compared with the general population. Mortality index exceeds that of in the population 2.1-fold. No one of the deceased had reached the average length of human life. Halt the cases died of ischemic heart disease, 6 patients developed carcinoma of endocrine organs; these were all females, who had taken radioactive iodine prior to the age of 30 years. Thus, in remote time periods after incorporation, there develop a number of those disorders leading ultimately to reduction of the length of human life, which is believed to be one of the universal effects of irradiation.     

Noncanonical conformation of nucleic acids: structure with slipped-loops, occurring in DNA oligonucleotides

A HPLC method was developed and validated for the quantitation of 9-cis-retinoic acid (ALRT1057) and its major metabolite, 4-oxo-9-cis-retinoic acid (LG100182) in human plasma. Samples were buffered and extracted with methyl-tert-butyl-ether. The analytes and an I.S. were separated on a C18 HPLC column using a shallow gradient of 70-89% organic solvent. The analytes were quantitated by UV detection at 348 nm. Selectivity against endogenous compounds and potential metabolites (retinol, all trans-, 13-cis-, and 4-hydroxy-9-cis-retinoic acid) was demonstrated. The run time was 29 min. The standard curve was linear from 2.5 to 450 ng ml-1. Interassay precision for both analytes in quality control samples was less than 5.0% RSD. Accuracy was within 11.0% RE for both compounds. Analyte stability during sample storage, extraction processing, and chromatography was established. Method ruggedness was tested by two analysts and on two HPLC systems. This method has been applied to the quantitation of clinical samples.     

The puncture and catheterization of the peripheral vessels using ultrasonic scanning

1% acetylcholine (5.5 10 M--acetylcholine chloride) applied directly to the cortex of conscious non-immobilized rabbits was established to produce neuroglial reaction in motor area. Following 30 min long application the number of astrocytes was significantly increased. Application lasting for 2 hrs resulted in a reverse effect. The above-mentioned changes were observed in surface and deep cortical layers. They were functional and could be attributed to the cell tinctorial properties.