Content of alginic acid and fucoidan in fucus algae of the Barents sea

Seasonal changes in the content of alginic acid and fucoidan have been studied in four species of fucus algae from the Barents sea: Fucus vesiculosus, F. distichus, F. serratus, and Ascophyllum nodosum. These polysaccharides are accumulated in the biomass of the algae during summer and autumn. To ensure complete processing of fucus algae it is recommended that the raw material be harvested within this period.     

A view of the cardiac rhythm control: Intrinsic regulation

Regulation of the cardiac rhythm is intricate and occurs at least at two major levels, intrinsic and extrinsic. In turn, each of these levels can be divided into several sublevels. The factors regulating the cardiac activity eventually affect the duration of spontaneous diastolic depolarization of pacemaker myocytes of the sinoatrial node and, to a far lesser extent, the conduction velocity in the conduction system of the heart. Intrinsic regulation of the heart rate (HR) includes the myogenic sublevel and the sublevels of cell-to-cell communication, the cardiac nervous system, and humoral factors produced within the heart. Myogenic regulation is considered to be the first sublevel in control of the cardiac function. The available data suggest myogenic regulation only for the contractility of the myocardium. The cell-to-cell regulation sublevel involves two principal mechanisms. One depends on the heterogeneous structure of the sinoatrial node and within-node shifts of the dominant pacemaker, which is a group of cells that determine the HR and govern all other cells of the sinoatrial node. The other mechanism is based on the effects of peptides produced by cardiomyocytes and endothelial cells on pacemaker cells of the sinoatrial node. Regulatory peptides are also produced by the cardiac nervous system, which includes sensory and effector autonomic fibers, represents the cardiac part of the metasympathetic system, and forms intramural ganglia. In addition to modulating the HR, these peptides affect the contractility, microcirculation, coronary blood flow, preload, and afterload. Currently available data demonstrate that the autonomic nervous system is far more intricate than believed earlier. Using various neuropeptides, this system provides for fine adjustment of the cell functions, subject to its immediate control.Translated from Fiziologiya Cheloveka, Vol. 31, No. 2, 2005, pp. 116–129.Original Russian Text Copyright © 2005 by Nozdrachev, Kotelnikov, Mazhara, Naumov.Deceased.     

Synthetic esters recognized by glucuronoyl esterase from <Emphasis Type="Italic">Schizophyllum commune</Emphasis>

Glucuronoyl esterase is a novel carbohydrate esterase recently discovered in the cellulolytic system of the wood-rotting fungus Schizophyllum commune on the basis of its ability to hydrolyze methyl ester of 4-O-methyl-d-glucuronic acid. This substrate was not fully corresponding to the anticipated function of the enzyme to hydrolyze esters between xylan-bound 4-O-methyl-d-glucuronic acid and lignin alcohols occurring in plant cell walls. In this work we showed that the enzyme was capable of hydrolyzing two synthetic compounds that mimic the ester linkages described in lignin-carbohydrate complexes, esters of 4-O-methyl-d-glucuronic and d-glucuronic acid with 3-(4-methoxyphenyl)propyl alcohol. A comparison of kinetics of hydrolysis of methyl and 3-(4-methoxyphenyl)propyl esters indicated that the glucuronoyl esterase recognizes the uronic acid part of the substrates better than the alcohol type. The catalytic efficiency of the enzyme was much higher with the ester of 4-O-methyl-d-glucuronic acid than with that of d-glucuronic acid. Examination of the action of glucuronoyl esterase on a series of methyl esters of 4-O-methyl-d-glucopyranuronosyl residues α-1,2-linked to xylose and several xylooligosaccharides suggested that the rate of deesterification is independent of the character of the carbohydrate part glycosylated by the 4-O-methyl-d-glucuronic acid.     

Relationships between hemorheology, erythrocyte metabolism, and von willebrand factor in athletes and patients with peripheral arterial disease

The relationship between hemorheology, erythrocyte ATP and 2,3-diphosphoglycerate (2,3-DPG) concentrations, and von Willebrand factor antigen was studied in athletes and peripheral arterial disease patients. Lower blood viscosity, mainly due to a higher erythrocyte deformability, was found in athletes compared to control subjects. Higher 2,3-DPG/Ht levels in athletes were correlated with blood viscosity, erythrocyte deformability, the rigidity index, and erythrocyte suspension viscosity at low shear stress. It is suggested that these relationships might be determined by the predominance of immature erythrocytes in the blood circulation of the athletes. In the group of patients, a decrease in ATP/Ht was related to increased erythrocyte aggregation and a higher erythrocyte suspension viscosity. Moreover, the concentration of von Willebrand factor was positively correlated with the erythrocyte aggregation index, erythrocyte suspension viscosity, and plasma viscosity. The results show that alterations in erythrocyte and plasma rheology may be involved in the modification of the functional state of the vascular endothelium and the development of atherosclerosis.     

DNA sequence-specific ligands: XIII. New Dimeric Hoechst 33258 molecules, inhibitors of HIV-1 integrase in vitro

Dimeric Hoechst 33258 molecules [dimeric bisbenzimidazoles (DBBIs)] that, upon binding, occupy one turn of the B form of DNA in the narrow groove were constructed by computer simulation. Three fluorescent DBBIs were synthesized; they consist of two bisbenzimidazole units tail-to-tail linked to phenolic hydroxy groups via penta- or heptamethylene or tri(ethylene glycol) spacers and have terminal positively charged N.N-dimethylaminopropyl carboxamide groups in the molecule. The absorption spectra of the DBBIs in the presence of different DNA concentrations showed a hypochromic effect and a small shift of the absorption band to longer wavelengths, which indicated the formation of a complex with DNA. The presence of an isobestic point in the spectrum indicates the formation of one type of DBBI-DNA complexes. The interaction of DBBIs with DNA was studied by CD using a cholesteric liquid-crystalline dispersion (CLD) of DNA. The appearance of a positive band in the absorption region of ligand chromophores in the CD spectrum of the DNA CLD indicates the formation of a DBBI-DNA complex in which ligand chromophores are arranged at an angle close to 54 degrees relative to the helix axis of DNA, which suggests the localization of the DBBI in the narrow groove of DNA. All the DBBIs were found to be in vitro inhibitors of HIV-1 DNA integrase in the 3'-processing reaction, and, of the three DBBIs, two dimers inhibit HIV-1 integrase even in submicromolar concentrations.     

Autonomic heart rate control and regional vascular reactions

Rheovasographic parameters (the thigh region) were recorded in groups of subjects with high and low heart rate variability (HRV). Correlation between the rheovasographic parameters and the sympathetic-parasympathetic balance value (LF/HF) was found. It was established that vagosympathetic balance in the first group was interrelated with the parameters of the ascending portion of the rheological wave; in the second group, with the parameters characterizing the blood flow in the microcirculatory bed. Thus, predominance of the autonomic loop of regulation mainly ensures an optimal regional arterial blood flow; the predominance of the central loop of regulation of cardiac activity, an optimal blood flow in microvessels.     

Age-related characteristics of the formation of neurophysiological mechanisms of the phonemic, grammatical, and semantic linguistic levels

The structure of regional interactions of brain bioelectric potentials has been studied during performance by adults (n = 18) and children aged five to six (n = 15) and eight to nine years (n = 17) of three analytical verbal tasks: recognition of a given phoneme in the context of auditory presented words and recognition of grammatical and semantic mistakes in auditory presented sentences. According to the data of cross-correlation and coherent EEG analyses, adults and, to a lesser extent, children of both age groups showed a noticeable intensification of interhemispheric interaction during the performance of all three tasks, especially between temporal areas, with relatively minor changes in ipsilateral EEG relations. Children were shown to have elements of immaturity of neurophysiological mechanisms underlying various aspects of the language function, such as the analysis of the grammatical formation of a verbal utterance and the semantic content of a phrase. The results also suggest that the level of maturation of neurophysiological mechanisms underlying phonemic analysis is somewhat higher at these age stages than the level of maturity of central mechanisms responsible for the analysis of the semantic content and grammatical construction of a phrase. Quantitative comparison of the patterns of spatial interaction of cortical bioelectric potentials recorded during the performance of the tasks related to different linguistic levels showed a high degree of their statistical similarity for each of the age groups. The findings confirm the assumption that the distributive central maintenance of different linguistic levels is based on topologically close constellations of interacting cortical areas and on similar organization of their regional interactions.     

Hyperkalemic normothermic hypoperfusion of the isolated heart

It is established that both normothermic hypoperfusion of the heart by cardioplegic solution and pharmacocardioplegia with cold protect myocardium from the ischemic damage.     

The role of inhibition processes in the development of functional properties of neurons of the vibrissa projection area in the cat somatosensory cortex

The paper deals with the contribution of intracortical inhibitory processes to the organization of receptive fields in the vibrissae projection area of the somatosensory cortex. Inhibition blockade by means of microelectrophoretic application of picrotoxin and bicucullin was shown to lead to a loss of directional sensitivity of neurones. Activation of inhibition at remote glutamate application led to opposite changes: the neurones became directionally sensitive, and dependence was found between the spatial localization of activated neurones and the character of changes of detector parameters. Inhibitory processes caused by natural afferent stimulation led to similar changes of functional characteristics of neurones.