Receptor-mediated biological effects of extracts obtained from three species.

This study reports the effects of aqueous extracts obtained from three fern species of Bulgarian origin: L., L., and L.

Biochemical Changes in Experimental Rat Model of Abdominal Compartment Syndrome.

Background: Increased intra-abdominal pressure (IAP) causes tissue ischemia, subsequent hypoxia, and impairment of normal tissue metabolism. Elevation of IAP above 20 mmHg leads to progression of abdominal compartment syndrome (ACS) that is associated with organ dysfunction or failure not previously manifested.

Aim: To evaluate the eff ects of diff erent grades and time of exposure to IAP on biochemical parameters and oxidative stress in organs aff ected by ischemia using previously developed rat model.

Application of solid-phase extraction for the concentration of chromophores, fluorophores, and photosensitizers from lens protein digests.

Solid-phase extraction was applied for the separation of protein digests obtained from aged human lenses, cataractous human lenses, calf lens proteins in vitro glycated with dehydroascorbic acid and native calf lens proteins. Four fractions were collected after stepwise elution with different solvents. The first fraction contained about 80% of the digested material possessing free amino groups.

New biological properties of coffee melanoidins.

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 potentials. In the presence of 1 × 10⁻⁶ mol L⁻¹ acetylcholine and 1 × 10⁻⁶ mol L⁻¹ arecoline the melanoidin-evoked contraction was significantly reduced.

Sensitizing effect of tacrine on M-cholinergic receptors in gastric smooth muscle of rats.

Aim: To find if tacrine exerts a sensitizing effect on the cholinergic receptors of gastric smooth muscles, and study some of the mechanisms inducing it and measure the relative intensity of tacrine's effects on contractile activity.

Material And Methods: Isometric recording of the mechanical activity of gastric smooth muscle preparations; determination of acetyl-cholinesterase activity in smooth-muscle tissue homogenates using Ellman's method.

Results: We found that the threshold concentration for tacrine not reducing the acetylcholinesterase activity and not having an effect on the smooth muscle preparations was 1 x 10(-8) mol/l.

Testing biological activity of model Maillard reaction products: studies on gastric smooth muscle tissues.

Water-soluble Maillard reaction products obtained from five different model systems were investigated for their effects upon the mechanical activity of rat gastric smooth muscle. Most of the total Maillard reaction products applied at concentration of 1.5 mg/ml evoked contractions; among them the product obtained from arginine and glucose (Arg-Glc) produced the most powerful contractions.

Iodine status and goitre prevalence in nitrate-exposed schoolchildren living in rural Bulgaria.

Nitrate and perchlorate are well-known water pollutants that are harmful to human health. They may inhibit the accumulation of iodide in the thyroid gland. The present study investigated iodine status and goitre prevalence in schoolchildren aged 7-14 years from two villages in Bulgaria with high and low levels of nitrate, and negligible levels of perchlorate in drinking water.

High-nitrate levels in drinking water may be a risk factor for thyroid dysfunction in children and pregnant women living in rural Bulgarian areas.

Nitrate inhibits the accumulation of iodide in thyroid gland. The aim of present study was to evaluate the influence of this ion on the iodine status of two risk population groups. Subjects of study were pregnant women and children aged between 3 and 6 years from two villages in Bulgaria with high- and low-nitrate levels in drinking water.

Effect of tacrine on cytosolic Ca2+ level and calmodulin in gastric muscle tissues of rat.

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.

Iodine status of children living in areas with high nitrate levels in water.

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 the total number of exposed (179.

Influence of model melanoidins on calcium-dependent transport mechanisms in smooth muscle tissue.

Melanoidins obtained from L-arginine and D-glucose (MW > 3500 Da) were tested for their ability to influence the contractility of gastric smooth muscles. A study within the range 0.1-10 mg/mL revealed that at low concentrations, the melanoidins provoked concentration-dependent contraction, whereas a muscle relaxation was registered at high concentrations.

Calcium-independent tacrine-induced relaxation of rat gastric corpus smooth muscles.

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 followed by a prolonged relaxation. To shed some light on the mechanism underlying this untypical relaxation, the amplitude of mechanical reactions caused by tacrine were compared with those of tacrine in the presence of atropine, ipratropium, metrifonate, TTX, nifedipine, D-600, caffeine, apamin, and charybdotoxin. The results obtained revealed that the relaxation was neither cholinergic in nature, nor mediated by the influence of the drug on intramural neuronal structures.

Non-anticholinesterase, non-cholinergic effect of tacrine on gastrointestinal smooth muscle tissues of rat.

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.

Photosensitizer activity of model melanoidins.

This study investigates the potential of melanoidins, the brown pigments formed during Maillard reaction in thermally processed foods, to act as photosensitizers. Seven model melanoidins obtained from different amino and carbonyl compounds were irradiated in a photoreactor or exposed to sunlight. Changes in the ultraviolet-visible spectra and photobleaching were registered in all studied melanoidin systems, and reactive oxygen species were quantified.

Activation of protein-bound copper ions during early glycation: study on two proteins.

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.

Glycated proteins can enhance photooxidative stress in aged and diabetic lenses.

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 acid, or fructose to obtain models of aged and diabetic cataractous lenses. Being exposed to 200J/cm2 UVA radiation the model glycated proteins produced 2-3-fold more singlet oxygen compared to the unmodified protein and the superoxide radical formation was 30-80% higher than by the native protein.

Region-specific pathophysiological alterations occurring in calf lenses in vitro during hyperglycemia.

Background: The early onset of cataract during diabetes may come about via a variety of pathogenic pathways, but an uncertainty about the significance of each of them exists.

Methods: Calf lenses cultured in a high glucose medium were investigated for regional variations in sorbitol accumulation, changes in lactate dehydrogenase activity, and formation of carbonyl groups in proteins. The results obtained were used to evaluate the contributions of various pathways to the alterations in the lens during hyperglycemia and to relate these findings to morphologically diverse lens substructures.