Mariana D. Argirova

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This study proposes several possible pathways by which hyperglycemia could make protein-bound metal ions more redox active. These mechanisms were tested on bovine serum albumin and calf lens protein. Proteins rich in early glycation products were less capable of competing for copper ions in the presence of other ligands (e.g., glycine and calcein),(More)
Cataract is generally associated with the breakdown of the lens microarchitecture. Age-dependent chemical modifications and cross-linking of proteins are the major pathways for development of lens opacity. The specific alterations in lens proteins caused by glycation with four carbonyl metabolites, fructose, methylglyoxal, glyoxal, and ascorbic acid, were(More)
This study intends to clarify the ability of different carbonyl-containing lens metabolites to form advanced glycation end products, which possess photosensitizer activity and to investigate whether these modified proteins could be implicated in lens photodamage. Calf lens protein was experimentally glycated with either methylglyoxal, glyoxal, ascorbic(More)
Water-soluble melanoidins isolated from roasted coffee induced ex vivo changes in the bioelectric and contractile activity of rat circular gastric smooth muscle tissues. They provoked a depolarization of smooth muscle cellular membranes and an increase in Ca²⁺-influx as evidenced by the increase in the frequency and amplitude of Ca²⁺-generated spike(More)
INTRODUCTION Tacrine is an acetylcholinesterase inhibitor. It has an indirect cholinomimetic effect inducing contractions of the gastric smooth muscles. The contractions are related to the effect of the accumulated acetylcholine in tissues on the respective choline receptors. There is a well defined direct correlation between tacrine concentrations and the(More)
Tacrine, a non-competitive reversible acetylcholinesterase and butyrylcholineserase inhibitor, caused a concentration-dependent tonic contraction of gastric smooth muscle preparations in the concentration range 1 x 10(-7) mol/L - 1 x 10(-5) mol/L, whereas concentrations higher than 2 x 10(-5) mol/L induced a biphasic effect; a short-time contraction was(More)
INTRODUCTION Tacrine is a cholinesterase inhibitor used for the treatment of Alzheimer's disease. The drug also has an effect on a number of tissues and organs that are not targets of its therapeutical action in this disease. The gastrointestinal tract is one such affected organ. AIM To investigate the in vitro effects of tacrine on rat stomach smooth(More)
The effects of three dipeptides L-phenylalanyl-glybine, glycyl-L-phenylalanine,and aspartame (L-aspartyl-L-phenylalanine, methyl ester) as inhibitors of the ascorbic acid-induced modifications in lens proteins were studied. Their efficiency was compared to that of two known inhibitors--aminoguanidine and carnosine. The tested dipeptides diminished protein(More)
The one-step incorporation of ascorbyl palmitate (AP), a widely used derivative of vitamin C, into nanofibrous mats of poly(ɛ-caprolactone) (PCL) by electrospinning was demonstrated. The incorporation of AP was attested by IR spectroscopy; the AP content was determined by thermogravimetric analysis (TGA); and the surface composition of the mats: by X-ray(More)
Several researchers have suggested a possible relationship between nitrate intake and the development of goiter in children. The present cross-sectional study included schoolchildren between the ages of 11 and 14 years from 2 villages in Bulgaria with high and low nitrate levels in drinking water. The comparison between the median urinary iodine levels of(More)