Alterations in the creatine kinase system in the myocardium of cardiomyopathic hamsters

Immunochemical and biochemical methods were used to assess quantitatively the changes in the heart creatine kinase system in the myopathic Syrian hamsters, line CHF I46. Cardiomyopathy in I75-200 day old animals was characterized by decreased content of mitochondria and lower total creatine kinase activity. In isolated mitochondria only the creatine kinase activity was decreased while cytochromes aa3 content and respiration rate were unchanged. The share of mitochondrial creatine kinase in the total tissue enzyme activity was decreased from 33% to I8% and that of BB form was elevated from 5% in control to 20%, at unchanged relative level of MM. Immunoassay showed decreased amount of the mitochondrial creatine kinase in the tissue and its decreased ratio to cytochromes aa3. The results show altered expression of creatine kinase isoenzymes in cardiomyopathy.     

Bifurcation analysis of periodic SEIR and SIR epidemic models

The bifurcations of the periodic solutions of SEIR and SIR epidemic models with sinusoidally varying contact rate are investigated. The analysis is carried out with respect to two parameters: the mean value and the degree of seasonality of the contact rate. The corresponding portraits in the two-parameter space are obtained by means of a numerical continuation method. Codimension two bifurcations (degenerate flips and cusps) are detected, and multiple stable modes of behavior are identified in various regions of the parameter space. Finally, it is shown how the parametric portrait of the SEIR model tends to that of the SIR model when the latent period tends to zero.     

Detection of human neuronal α7 nicotinic acetylcholine receptors by conjugates of snake α-neurotoxin with quantum dots

Fluorescent derivatives are widely used to study the structure and functions of proteins. Quantum dots (QDs), fluorescent semiconductor nanocrystals, have a high quantum yield and are much more resistant to bleaching compared to organic dyes. Conjugates of α-neurotoxins with QDs were used for visualization of human α7 acetylcholine receptors heterologously expressed in GH4C1 pituitary adenoma cells. Specific staining of cells by the conjugated toxins was observed.     

Detection of mitochondrial defects by laser fluorimetry

The mitochondrial function in skeletal muscle biopsies of three patients with chronic progressive external ophthalmoplegia, having deletions of the mitochondrial DNA, was studied by laser-excited fluorescence measurements of NAD(P)H and flavoproteins in saponin-skinned fibers. We detected substantially elevated steady state redox states of the mitochondrial NAD-system in the muscle fibers of these patients. Moreover, the respiratory chain-linked autofluorescence changes in the muscle fibers of these patients were larger in comparison to controls indicating substantial alterations of the mitochondrial content. These results are in line with the presence of elevated numbers of partially respiratory chain inhibited mitochondria in the skeletal muscle of chronic progressive external ophthalmoplegia patients. (Mol Cell Biochem 174: 97–100, 1997)     

Molecular mechanisms of antitumor activity of the polymeric form of niclosamide with respect to human colorectal cancer cells

Using poly(lactic-co-glycolic) acid a polymeric form of niclosamide (PFN) has been developed and its antitumor activity against human colorectal cancer cell lines SW837, Caco-2, COLO 320 HSR has been investigated in comparison with free niclosamide. PFN was shown to be more cytotoxic against cancer cells and less cytotoxic against normal cells (human embryonic lung fibroblasts) as compared to niclosamide. Free niclosamide and PFN share a common mechanism of the cytotoxic action on tumor cells, which is associated with mitochondrial damage (evaluated as a decrease in rhodamine 123 accumulation), and increased levels of reactive oxygen species, particularly mitochondrial superoxide anion, causing oxidative damage of intracellular targets. The action of niclosamide and PFN was accompanied by G₀/G₁ cell cycle arrest.     

On the properties and sequence context of structurally ambivalent fragments in proteins

The goal of this work is to characterize structurally ambivalent fragments in proteins. We have searched the Protein Data Bank and identified all structurally ambivalent peptides (SAPs) of length five or greater that exist in two different backbone conformations. The SAPs were classified in five distinct categories based on their structure. We propose a novel index that provides a quantitative measure of conformational variability of a sequence fragment. It measures the context-dependent width of the distribution of (phi,xi) dihedral angles associated with each amino acid type. This index was used to analyze the local structural propensity of both SAPs and the sequence fragments contiguous to them. We also analyzed type-specific amino acid composition, solvent accessibility, and overall structural properties of SAPs and their sequence context. We show that each type of SAP has an unusual, type-specific amino acid composition and, as a result, simultaneous intrinsic preferences for two distinct types of backbone conformation. All types of SAPs have lower sequence complexity than average. Fragments that adopt helical conformation in one protein and sheet conformation in another have the lowest sequence complexity and are sampled from a relatively limited repertoire of possible residue combinations. A statistically significant difference between two distinct conformations of the same SAP is observed not only in the overall structural properties of proteins harboring the SAP but also in the properties of its flanking regions and in the pattern of solvent accessibility. These results have implications for protein design and structure prediction.     

Characterization of plant phenolic compounds by cyclic voltammetry

Phenolic acids and flavonoids were characterized by cyclic voltammetry and total antioxidant activity in the reaction with the ABTS cation radical. Anode peak voltages (E_ap) and their pH dependences were determined for the studied phenolic acids and flavonoids. The E_ap and Trolox equivalent antioxidant capacity (TEAC) values were found to correlate for polyphenols, which react with the ABTS cation radical in two steps. Correlation between the half-wave potential (E_1/2) and TEAC was determined for electrochemically irreversible compounds. Mechanisms of the reaction of phenolics on the electrode involving one-and two-electron oxidation are proposed.     

Anoxygenic phototrophic bacteria from microbial communities of Goryachinsk thermal spring (Baikal Area,Russia)

Species composition of anoxygenic phototrophic bacteria in microbial mats of the Goryachinsk thermal spring was investigated along the temperature gradient. The spring belonging to nitrogenous alkaline hydrotherms is located at the shore of Lake Baikal 188 km north-east from Ulan-Ude. The water is of the sulfate-sodium type, contains trace amounts of sulfide, and salinity does not exceed 0.64 g/L, pH 9.5. The temperature at the outlet of the spring may reach 54°C. The cultures of filamentous anoxygenic phototrophic bacteria, nonsulfur and sulfur purple bacteria, and aerobic anoxygenic phototrophic bacteria were identified using the pufLM molecular marker. The fmoA marker was used for identification of green sulfur bacteria. Filamentous cyanobacteria predominated in the mats, with anoxygenic phototrophs comprising a minor component of the phototrophic communities. Thermophilic bacteria Chloroflexus aurantiacus were detected in the samples from both the thermophilic and mesophilic mats. Cultures of nonsulfur purple bacteria similar to Blastochloris sulfoviridis and Rhodomicrobium vannielii were isolated from the mats developed at high (50.6–49.4°C) and low temperatures (45–20°C). Purple sulfur bacteria Allochromatium sp. and Thiocapsa sp., as well as green sulfur bacteria Chlorobium sp., were revealed in low-temperature mats. Truly thermophilic purple and green sulfur bacteria were not found in the spring. Anoxygenic phototrophic bacteria found in the spring were typical of the sulfur communities, for which the sulfur cycle is mandatory. The presence of aerobic bacteriochlorophyll a-containing bacteria identified as Agrobacterium (Rhizobium) tumifaciens in the mesophilic (20°C) mat is of interest.     

Effect of ABA on the contents of proline, polyamines, and cytokinins in the common ice plants under salt stress

The effects of ABA treatment on the contents of proline, polyamines (PA), and cytokinins (CK) in the facultative halophyte the common ice plant (Mesembryanthemum crystallinum L.) subjected to salt stress were studied. Plants grown in the phytotron chamber on Jonson nutrient medium for 6 weeks were subjected to 6-day-long salinity by a single NaCl adding to medium. During first three days of salinity, half plants of each treatment were placed for 30 min on nutrient medium containing 0, 100, or 300 mM NaCl plus ABA in the final concentration of 1 μM. Salinity reduced biomass accumulation and water and chlorophyll contents in plants. This was accompanied by the increase in the levels of MDA, proline, and sodium ions. ABA treatment of salt-stressed plants favored biomass accumulation and photosynthetic pigment protection, reduced the intensity of oxidative stress and the level of NaCl-induced proline accumulation. ABA treatment increased the contents of putrescine (Put) and spermidine (Spd) in the leaves and roots of control plants (not subjected to salt stress), reduced the losses of Put in the leaves and roots and Spd in the roots in the presence of 100 mM NaCl, and suppressed cadaverine (Cad) accumulation in the roots in the presence of 300 mM NaCl. In the presence of NaCl, ABA reduced the contents of zeatin and zeatin riboside and increased the level of zeatin-O-glucoside in the roots and isopentenyladenosine and isopentenyladenine in the leaves. Thus, ABA protective action under salinity can be realized through the weakening of oxidative stress (a decrease in MDA content) and the regulation of PA, proline, and CK metabolism, which has a great significance in plant adaptation to injurious factors.     

The number of the rat peritoneal cells in normal condition, blood loss, and under colchicine injection

The modification of peritoneal cells derivation method proposed for the peritoneum rat, and the absolute amount of peritoneal lymphocytes, monocytes, macrophages, stem and polymorphonuclear neutrophyles, mat cells was determined. The procedure of acute 2% blood loss was found to reduce the total amount of the peritoneal cells due to depletion of lymphocytes accompanied by an increase in amount and proliferative activity of monocyte peritoneal cells, stem neutrophiles appearance in the peritoneal cavity. The subcutaneous injection of colchicine solution reduces the number of the peritoneal macrophages in normal rats, decreases the number of the monocytes, polymorphonuclear neutrophiles and led to disappearance of the stem neutrophiles on the second day of blood loss.