Coenzyme protection of lactic dehydrogenase against inactivation by gamma-rays.
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Coenzymes↗
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Antibacterial Schiff bases of oxalyl-hydrazine/diamide incorporating pyrrolyl and salicylyl moieties and of their zinc(II) complexes.
Schiff bases derived from oxaldiamide/oxalylhydrazine and pyrrol-2-carbaldehyde, or salicylaldehyde respectively, as well as their Zn(II) complexes have been prepared and tested as antibacterial agents. These Schiff bases function as tetradentate ligands, forming octahedral Zn(II) complexes. The ketonic form for the diamide derived Schiff base and the enolic form of the hydrazide derived Schiff base were the preferred tautomers for coordination of the metal ions. The title compounds and their Zn(II) derivatives were evaluated for antibacterial activity against several bacterial strains which easily develop resistance to classical antibiotics, such as Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. Some of them showed promising biological activity in inhibiting the growth of such organisms.
Aldehydes↗
Inhibition of Trypanosoma cruzi alpha-hydroxyacid dehydrogenase-isozyme II by N-isopropyl oxamate and its effect on intact epimastigotes.
The effect of N-isopropyl oxamate on the activity of alpha-hydroxyacid dehydrogenase-isozyme II (HADH-isozyme II) from Trypanosoma cruzi was investigated. The kinetic studies showed that this substance was a competitive inhibitor of this isozyme. The attachment of the nonpolar isopropylic branched chain to the nitrogen of oxamate increased 12-fold the affinity of N-isopropyl oxamate for the active site of T. cruzi HADH-isozyme II. N-isopropyl oxamate was a selective inhibitor of HADH-isozyme II, since other T. cruzi dehydrogenases were not inhibited by this substance. Since HADH-isozyme II participates in the energy metabolism of T. cruzi, a trypanocidal effect can be expected with inhibitors of this isozyme. However, although it was not possible to detect any trypanocidal activity with N-isopropyl oxamate when the ethyl ester was tested as a possible trypanocidal prodrug, the expected trypanocidal effect was obtained, comparable to that obtained with nifurtimox and benznidazole.
Alcohol Oxidoreductases↗
Trypanocidal activity of N-isopropyl oxamate on cultured epimastigotes and murine trypanosomiasis using different Trypanosoma cruzi strains.
The trypanocidal activity of N-isopropyl oxamate (NIPOx) and the ethyl ester of N-isopropyl oxamate (Et-NIPOx) were tested on cultured epimastigotes (in vitro) and on murine trypanosomiasis (in vivo) using five different T. cruzi strains. When benznidazole and nifurtimox, used for comparison, were tested we found that only three of these T. cruzi strains were affected, whereas the other two strains, Miguz and Compostela, were resistant to the in vitro and the in vivo trypanocidal activity of these substances. In addition, when NIPOx was tested on cultured epimastigotes and on mice parasitaemia, trypanocidal activity was not obtained on either of these T. cruzi strains. Our experiments strongly suggest that NIPOx does not penetrate intact epimastigotes due to the polarity of its carboxylate whereas Et-NIPOx, acting as a prodrug, exhibited in vitro and in vivo trypanocidal activity in the five tested T. cruzi strains.
Alcohol Oxidoreductases↗
2'-modified oligonucleotides from methoxyoxalamido and succinimido precursors: synthesis, properties, and applications.
Synthesis of 2'-modified oligonucleotides from 2'-methoxyoxalamido (MOX) and 2'-succinimido (SUC) precursors is described. Their physical and biochemical properties were assessed. Synthesized oligonucleotides were used as primers in advanced DNA sequencing protocols. An example of sequencing directly off genomic DNA template without prior cloning or PCR amplification is presented.
Base Sequence↗
The MOX/SUC precursor strategies: robust ways to construct functionalized oligonucleotides.
The use of phosphoramidites bearing one or more methoxyoxalamido (MOX) or succinimido (SUC) reactive groups for construction of functionalized oligonucleotides is described. The efficiency of the new precursor strategy was demonstrated in the synthesis of oligonucleotide containing up to 16 imidazole residues.
Oligonucleotides↗
Effects of ketotifen 0.025% and lodoxamide 0.1% on eosinophil infiltration into the guinea pig conjunctiva in a model of allergic conjunctivitis.
The effects of ketotifen and lodoxamide on eosinophil infiltration were assessed in a guinea pig model of allergic conjunctivitis. The two active treatments were coded in this masked study in which 30 male guinea pigs, sensitized to chicken egg albumin (ovalbumin), were randomly assigned to one of three groups: Group 1, instillation of 0.9% NaCl into the conjunctival sac of both eyes; Group 2, instillation of 0.025% ketotifen into the left eye and 0.9% NaCl into the right eye; Group 3, instillation of 0.1% lodoxamide into the left eye and 0.9% NaCl into the right eye. Ovalbumin was administered topically to each eye, except in Group 1 where it was only applied to the left eye. (111)In-oxine labeled eosinophils were injected into the jugular vein of each guinea pig; the animals were sacrificed 17 hours after ovalbumin had been applied. The level of radioactivity in the ketotifen- and lodoxamide-treated eyes was approximately 60% of that in the saline-treated eyes. Moreover, the mean level of radioactivity in the ketotifen- and lodoxamide-treated eyes was comparable with the mean level of radioactivity in the saline-treated eye of Group 1, which had not been exposed to allergen. These results indicate that the therapeutic effects of ketotifen and lodoxamide in allergic conjunctivitis may be partly mediated by an inhibitory effect on eosinophils.
Administration, Topical↗
24-well plate spectrophotometric assay for preliminary screening of metabolic activity.
A 90-min assay using 24-well plates was developed for screening overall metabolic effects of toxic chemicals by measuring extracellular acidification rate of mammalian cells. During the 90-min test, the pH of each well of a 24-well plate is monitored by measuring the absorbance of phenol red using a spectrophotometric plate reader. The acidification rate is then calculated from the change in pH divided by the time interval and cell density, which is also estimated non-invasively by spectroscopy. The assay was verified by testing the effects of five well-characterized chemical toxins on fibroblast cell cultures. As expected, the responses of the fibroblasts were dependent on the dose and type of toxin. They also corresponded with the established mechanisms of the toxins and with measured lactate production rates. The set-up is simple, inexpensive, and amenable to being automated. The method is easy to perform and rapid. Uses include screening compounds for gross metabolic effects in mammalian cell lines, determining preliminary metabolic dose-response curves for guiding further research, and designing and optimizing media for in vitro systems utilizing cell cultures.
2,4-Dinitrophenol↗
Glycolysis as primary energy source in tumor cell chemotaxis.
The energy requirements via glycolytic pathways were directly measured in migrating tumor cells. Motility in the metastatic human melanoma cell line A2058, stimulated by insulinlike growth factor I (IGF-I), depends on glycolysis in the presence of glucose as its principal source of energy. Motility in glucose-free medium was 75% reduced and utilized mitochondrial respiration (inhibited by oligomycin). With increasing (physiologic) glucose concentrations, there was a dramatic shift to anaerobic glycolysis as the energy source and 93% elimination of the oligomycin inhibition of motility. Oxamate, an inhibitor of glycolysis, inhibited motility at all glucose concentrations. CO2 production from glycolysis and from the hexose monophosphate shunt was measured in migrating tumor cells. The time course and glucose-dose dependence of glycolytic CO2 production correlated directly with motility. In contrast, mitochondrial CO2 production was inversely related to glucose concentration. A monoclonal antibody for the IGF-I receptor inhibited both motility and glycolytic CO2 production, indicating that both processes are receptor mediated.
Antibodies, Monoclonal↗
Purification and characterization of beta-N-acetylhexosaminidases and beta-galactosidase from Streptococcus 6646 K.
Three beta-N-acetylhexosaminidases [EC 3.2.1.52] and one beta-galactosidase [EC 3.2.1.23] were purified from the culture filtrate of streptococcus 6646 group K by a combination of column chromatographies on p-aminophenyl beta-D-thiogalactopyranoside-substituted Sepharose and N-(paminophenyl)oxamic acid-substituted Sepharose. These beta-N-acetylhexosaminidases showed optimal activities between pH 5.0 and 5.5 and could hydrolyze synthetic and glycopeptidic substrates. Glycolipids such as GM2, asialo-GM2, and globoside I were no susceptible to these beta-hexosaminidases. beta-Galactosidase, which was purified more than 11,000-fold, had a substrate specificity rather similar to that of beta-galactosidase from E. coli. This enzyme was inhibited by EDTA and activated by Mn2+, Ca2+, and Mg2+. Problems pertinent to the application of affinity chromatography to the purification of glycosidases are also discussed.
Cations, Divalent↗
Lack of involvement of mast cell degranulation in the antiarrhythmic effect of preconditioning in rats.
It has been proposed that the cardioprotective effects of myocardial ischaemic preconditioning may involve the release of mast cell mediators. The aim of the study was to determine whether mast cells are involved in the antiarrhythmic effect of ischaemic preconditioning in rat hearts. Preconditioning was achieved, both in anaesthetised rats and in rat isolated hearts, by a 3-min temporary occlusion of the left main coronary artery followed by 10 min of reperfusion before a 30-min permanent occlusion. Preconditioning had a marked antiarrhythmic effect, reducing the number of ventricular ectopic beats from 1,176 +/- 69 to 490 +/- 139 and the incidence of ventricular fibrillation from 40% to 0. Administration of the mast cell-stabilising drugs lodoxamide tromethamine and sodium cromoglycate (20 mg/kg/h i.v. 30 min before and throughout experimental protocol) did not modify the antiarrhythmic effect of preconditioning. Sodium cromoglycate, but not lodoxamide tromethamine, itself significantly reduced the number of ectopic beats that occurred over a 30-min period of ischaemia (from 760 +/- 181 to 153 +/- 33 in nonpreconditioned animals). Both drugs abolished the decrease in arterial blood pressure that occurred on coronary artery occlusion. The decrease in arterial blood pressure produced by the mast cell-degranulating compound 48/80 (50 microg/kg; i.v.) was attenuated to a similar degree by both drugs (decreases in pressure of 53 +/- 7, 31 +/- 1, and 25 +/- 3 mm Hg in control, sodium cromoglycate-treated, and lodoxamide tromethamine-treated animals, respectively). In rat isolated hearts, degranulation of mast cells with three consecutive doses of 50 microg of compound 48/80 had no antiarrhythmic effects and did not modify the antiarrhythmic effect of preconditioning. It is concluded that cardiac mast cells do not play a major role in the protection offered by ischaemic preconditioning on arrhythmogenesis in rat hearts.
Animals↗
Lacrimal occlusion therapy for the treatment of superior limbic keratoconjunctivitis.
Superior limbic keratoconjunctivitis (SLK) is a chronic and recalcitrant disease of the superior bulbar and tarsal conjunctiva, as well as the superior limbic aspect of the cornea. Both the etiology and the pathogenesis of this condition are poorly understood. Many treatment options have been advocated in the management of SLK, including: topical antibiotics, topical anti-inflammatory agents, topical vitamin A solutions, chemical cautery, thermal cautery, and surgical resection. Most recently, studies have suggested that lacrimal occlusion therapy may be beneficial in the treatment of SLK. A case is presented in which this method of treatment was used, with excellent results. The implications of this report suggest that the use of lacrimal occlusion in the management of SLK may be a viable treatment option before considering more radical and invasive therapy. In addition, this case helps to illustrate the significant link between SLK and thyroid disease.
Adult↗
Secondary bacterial keratitis associated with shield ulcer caused by vernal conjunctivitis.
PURPOSE: To report a patient with vernal keratoconjunctivitis-induced shield ulcer superinfected with Staphylococcus aureus. METHODS: Observational case report. A 12-year-old boy who had been followed for vernal keratoconjunctivitis for 3 years was admitted to our clinic complaining of visual loss, photophobia, and a ropy discharge. On slit-lamp examination, a transversely oval shield ulcer, which was situated in the center of the superior third of the cornea, was seen in the left eye. The vernal corneal plaque area and margins were infiltrated, and hypopyon was also observed. With the diagnosis of shield ulcer with secondary bacterial keratitis and hypopyon, the patient underwent medical treatment consisting of topical fortified cefazolin (50 mg/mL) and tobramycin (14 mg/mL), lodoxamide 0.1%, prednisolone acetate 1%, cyclopentolate, and systemic cetirizine. RESULTS: After treatment, the bacterial keratitis, shield ulcer, and inflammation in the anterior chamber disappeared. CONCLUSION: Bacterial keratitis associated with shield ulcer may be rarely observed in patients with vernal keratoconjunctivitis. Prompt diagnosis and treatment may prevent permanent complications and vision loss.
Anti-Bacterial Agents↗
Antiallergic activity of topical lodoxamide on in vivo and in vitro models.
Lodoxamide is an antiallergic drug acting as a mast-cell stabilizer, which is effective in the treatment of allergic conjunctivitis. The study aimed to evaluate the effect of lodoxamide eye-drops on the inflammatory early-phase reaction (EPR) changes induced by allergen-specific conjunctival challenge (ASCC). This was a cross-over, double-blind, placebo-controlled, randomized study, including 10 outpatients suffering from allergic rhinoconjunctivitis due to Parietaria judaica. Patients received one drop of lodoxamide tromethamine 0.1% or placebo 30 min before each ASCC. Clinical evaluation and cytologic assessment were done at baseline and 30 min after each ASCC. Lodoxamide induced a reduction in total symptom score and hyperemia during the EPR (P < 0.05). Lacrimation, itching/burning, and eyelid swelling were only slightly (nonsignificantly) reduced. Lodoxamide induced a reduction in the total number of inflammatory cells and neutrophils during the EPR (P < 0.02). Eosinophil and lymphocyte number and ICAM-1 expression showed only a slight, not statistically significant decrease. Placebo did not affect the studied parameters. Lodoxamide reduced early clinical events and cellular changes after ASCC consistently with its activity as mast-cell stabilizer. Moreover, lodoxamide was able to downregulate in vitro ICAM-1 expression on the continuously cultured, differentiated conjunctival cell line WK. This was shown both in basal conditions (P < 0.05) and upon interferon-gamma stimulation (P < 0.03), although at high concentration.
Adolescent↗
Conformation of the oxalamide group in retro-bispeptides. Three crystal structures.
We have determined the structures of a range of peptides having the oxalamide (-NH-CO-CO-NH-) unit located at their center. The oxalamide group has the trans conformation in two retropeptides and an approximately orthogonal conformation in the peptide with Pro residues. Torsional angles about the CO-CO bond are 180 degrees in MeO-Aib-CO-CO-Aib-OMe (1), 175 degrees in MeO-L-Leu-CO-CO-L-Leu-OMe (2), and -108 and -106 degrees for the two independent molecules in the crystal of MeO-L-Pro-CO-CO-L-Pro-OMe (3), owing to steric hindrance between CO and the pyrolidine ring. Crystal data are: (1) C12H20N2O6, triclinic, space group P1, a = 6.190(1), b = 10.044(2), c = 11.989(2) A, alpha = 86.13(12), beta = 83.13(2), gamma = 80.16(2) degrees, R = 0.057 for 1646 observed reflections [magnitude of Fo > 3 sigma (magnitude of Fo)]; (2) C16H28N2O6, tetragonal, space group P4(1), a = b = 11.121(3), c = 15.775(6) A, R = 0.058 for 1216 observed reflections [magnitude of Fo > 3 sigma (magnitude of Fo)]; (3) C14H20N2O6, monoclinic space group P2(1), a = 9.556(2), b = 17.864(3), c = 9.618(2) A, beta = 104.35(1) degree; R = 0.051 for 2100 observed reflections [magnitude of Fo > 3 sigma (magnitude of Fo)].
Amides↗
Sialidase in rabbit blood. Characterization of sialidase purified from rabbit erythrocyte membrane.
Sialidase activities of rabbit blood cells and serum were measured. The leucocyte particulate fraction showed the highest specific activity of sialidase towards mixed gangliosides and sialyllactose, and the cytosolic fraction showed for fetuin. Predominant sialidase activity in the blood was detected in erythrocyte particulate fraction when mixed gangliosides were used as substrate. The sialidase for ganglioside was solubilized from the erythrocyte ghosts by using Triton X-100. The solubilized sialidase was purified 1886-fold by sequential chromatographies on DEAE-cellulose, EAH-Sepharose 4B, Octyl-Sepharose CL-4B, Sephadex G-100, concanavalin-A--Sepharose, N-(p-aminophenyl)oxamic acid-agarose and Heparin-Sepharose CL-6B. The optimum pH of purified sialidase was 4.5 for ganglioside mixture, and this enzyme exhibited M(r) = 48,000 by gel filtration. When the purified sialidase was subjected to SDS/PAGE, a major sialidase-active protein band at M(r) = 54,000 and another fainter inactive protein band with M(r) = 115,000 were observed. The purified enzyme was active towards oligosaccharides, gangliosides, fetuin glycopeptide and 4-methylumbelliferyl alpha-D-N-acetylneuraminic acid except for glycoproteins tested. Fe2+, Fe3+ and dithiothreitol significantly inhibited the enzyme activity, while Triton X-100 activated the enzyme. Inside-out vesicles and unsealed ghosts of rabbit erythrocyte showed the sialidase activity for mixed gangliosides but not for resealed ghosts or intact erythrocytes. These results indicate that the active site of this sialidase is oriented mainly on the inside of the erythrocyte membrane and not on the outside. Treatment of rabbit erythrocyte unsealed ghosts with phosphatidylinositol-specific phospholipase C liberated no sialidase activity toward mixed gangliosides from the ghosts.
Animals↗
Mast cell degranulation and glucose homeostasis.
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Animals↗
Pathogenicity of stable L-phase variants of Staphylococcus aureus: failure to colonize normal and oxamide-induced hydronephrotic renal medulla of rats.
The direct intramedullary inoculation of stable L-phase variants of Staphylococcus aureus failed to colonize normal and hydronephrotic rat kidneys induced by oral feeding of oxamide.
Amides↗