Development of examination stress in subjects with various levels of cortical activation

The work is aimed at the study of neurophysiological mechanisms of examination stress in subjects with different levels of cortical activation. Spectral power and typical cortical connections of EEG rhythms were studied in students under conditions of stress before and immediately after examination as well as during usual academic semester. Students with relatively higher and relatively lower baseline alpha rhythm, i.e., with different levels of cortical activation revealed both similar and different EEG reactions. Before examination, in both groups of subjects the spectral power of EEG activity in the delta and thetal bands increased, and the number of connections in the bands of the alpha and beta 1 rhythms decreased as compared to usual baseline conditions. However, the EEG reactions in the theta 2 band in the two groups were oppositely directed. Significant changes in the beta 2 power were observed only in the group of subjects with higher baseline level of cortical activation.     

Comparative study of the M.Bstf5I-1 and M.BstF5I-3 DNA methyltransferases from the Bacillus stearothermophilus F5 restriction-modification system

The BstF5I restriction-modification system from Bacillus stearothermophilus F5, unlike all known restriction-modification systems, contains three genes encoding DNA methyltransferases. In addition to revealing two DNA methylases responsible for modification of adenine in different DNA strands, it has been first shown that one bacterial cell has two DNA methylases, M.BstF5I-1 and M.BstF5I-3, with similar substrate specificity. The boundaries of the gene for DNA methyltransferase M.BstF5I-1 have been verified. The bstF5IM-1 gene was cloned in pJW and expressed in Escherichia coli. Homogeneous samples of M.BstF5I-1 and M.BstF5I-3 were obtained by chromatography with different sorbents. The main kinetic parameters have been determined for M.BstF5I-1 and M.BstF5I-3, both modifying adenine in the recognition site 5'-GGATG-3'.     

Spectral power and cortical interactions in the beta2 rhythm in normal subjects and schizophrenic patients

Spectral and coherence characteristics of the beta 2 rhythm (20-40 Hz) were compared in patients with acute schizophrenia (the first episode), patients with chronic schizophrenia (disease duration more than two years), and healthy subjects (control group) during cognitive task performance. Examination showed the "excessive" spectral power of this rhythm in the prefrontal cortical areas in patients with acute schizophrenia and its "insufficient" spectral power in all derivations of the right hemisphere in patients with the chronic form as compared to the controls. The similarity of the beta 2 spectral power distribution in different cortical areas measured by covariance method decreased with increase in psychopathologic manifestations. Coherent analysis revealed a substantially lower number of cortico-cortical functional connections in schizophrenic patients than in healthy subjects, absence of interhemispheric connections in patients with acute schizophrenia, and a slight increase in their number if patients with the chronic disease. However, as distinct from the controls revealing many inter- and intrahemispheric connections in all cortical areas, in schizophrenics the interhemispheric connections were observed only in the posterior cortical regions. The results point to a disorder of interhemispheric interaction in schizophrenia.     

Modification of hyaluronic acid with aromatic amino acids

Hyaluronic acid was modified with aromatic amino acids (5-aminosalicylic, 4-aminosalicylic, anthranilic, and p-aminobenzoic) in the presence of 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide. The modified glycans contained 9–43% of arylamide groups and 10–33% of isoureidocarbonyl groups depending on the nature of the amino acid. Reduction with sodium borohydride allowed the conversion of isoureidocarbonyl groups into hydroxymethyl groups.Translated from Bioorganicheskaya Khimiya, Vol. 31, No. 1, 2005, pp. 90–95.Original Russian Text Copyright © 2005 by Ponedelkina, Odinokov, Vakhrusheva, Golikova, Khalilov, Dzhemilev.     

Seasonal dynamics of the component community structure of parasites of the minnow Phoxinus phoxinus (L.)

The material represented by 75 specimens of minnow of the age 2-2(+) was collected according to the standard technique in the Chovju River (tributary of the Vychegda River, a region of the settlement Nizniy Chov, district of Syktyvkar town) during the period June-September 2000. The quantitative estimation of the structure of the component parasite communities was performed by calculating errors of the equation of regression for each species group separately, with subsequent summarizing of means of errors by all parasite groups comprising the community (Dorovskikh, 2001 6; 2002 B). In order to have a possibility to get data complementing each other, the calculation of variety indexes and other indexes have been made for metazoan parasites only and for the whole community, including the protozoan parasites. In both cases, i.e. considering only metazoan parasites and the whole composition of parasite species, three states of the component parasite community have been recognised: the formed community (June), the community in destroying (July and August), the community in the process of formation (September). In the course of working on the total species composition we recorded the beginning of community destroying on 30th of June, and the beginning of community formation in August. Considering only the metazoan parasites, the community is defined (after: Pugachev, 1999) as the mature (balanced) one in June, while in July, August and September, it was unmature (off-balance) by its characteristics. Regarding the protozoan parasites, the community in June, August and September was characterized as the mature one based on indices of parasite biomass, and as unripe one based on the number of parasite individuals; however in July, both groups of indices allowed to refer it to the unripe state. However, these unripe states are essentially different. In July, it is the result of dieing out the parasites of the past generation; in August and September, it is the result of the appearances of new generations. Therefore we recognise three states of parasite community named above. Considering the whole species composition of parasites we noted the greater difference of index values based on the parasite specimen numbers and their conventional biomass, that was in the case of the metazoan parasites only. It is particularly noticeable in the middle of the June, in the period of the formed community. This fact, together with high errors of the equations of regression and the presence of the high number of Apiosoma, points to the disturbance in the structure of component parasite community in the minnow from the Chovju River. This is easily explicable, because the Chovju River is the polluted reservoir, and pollution comes from agricultural fields, Verhny-Chov settlement, pigsties and cow-sheds. The pollution is a seasonal factor here. The most powerful pollution was noted at May-June, and then it decreased along the beginning of rains in the end of August; in September it increased again. It is important to point out that the monitoring of the metazoan parasites only allows to reveal the general dynamics of the community during the period of observation, but does not allow to catch the beginning of its destroying and developing and to notice possible disturbances in the community structure caused by pollution of reservoirs, particularly, if this pollution is a seasonal factor as in the Chovju River. Three named states of the component community of the fish parasites take place in other periods of year than this observed in the intestional parasite communities of fish helminths of the temperate climate zone. The developing of parasite communities of the intestinal helminths of the Anguilla anguilla in England (Kennedy, 1997) and of Leuciscus idus from the Rybinsk reservoir (Zhohov, 2003) starts in the beginning of summer. In May, their species diversity is minimal and in August is maximal. In conditions of the middle stream of the Vychegda River, the species diversity of parasite community associated with the minnow is maximal in June and minimal in August, when it only begins developing.     

Modification of hyaluronic acid with aromatic amino acids

Hyaluronic acid was modified with aromatic amino acids (5-aminosalicylic, 4-aminosalicylic, anthranilic, and p-aminobenzoic) in the presence of 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide. The modified glycans contained 9-43% of arylamide groups and 10-33% of isoureidocarbonyl groups depending on the nature of the amino acid. Reduction with sodium borohydride allowed the conversion of isoureidocarbonyl groups into hydroxymethyl groups.     

The Role of Endogenous Calcitonin Gene-Related Peptide in the Neurotransmitter Quantal Size Increase in Mouse Neuromuscular Junctions

Changes in parameters of spontaneous acetylcholine (ACh) quantal secretion caused by prolonged high-frequency burst activity of neuromuscular junctions and possible involvement of endogenous calcitonin gene-related peptide (CGRP) and its receptors in these changes were studied. With this purpose, miniature endplate potentials (MEPPs) were recorded using standard microelectrode technique in isolated neuromuscular preparations of m. EDL–n. peroneus after a prolonged high-frequency nerve stimulation (30 Hz for 2 min). An increase in the MEPP amplitudes and time course was observed in the postactivation period that reached maximum 20–30 min after nerve stimulation and progressively faded in the following 30 min of recording. Inhibition of vesicular ACh transporter with vesamicol (1 μM) fully prevented this “wave” of the MEPP enhancement. This indicates the presynaptic origin of the MEPP amplitude increase, possibly mediated via intensification of synaptic vesicle loading with ACh and subsequent increase of the quantal size. Competitive antagonist of the CGRP receptor, truncated peptide isoform CGRP_8–37 (1 μM), had no effect on spontaneous secretion parameters by itself but was able to prevent the appearance of enhanced MEPPs in the postactivation period. This suggests the involvement of endogenous CGRP and its receptors in the observed MEPP enhancement after an intensive nerve stimulation. Ryanodine in high concentration (1 μM) that blocks ryanodine receptors and stored calcium release did not influence spontaneous ACh secretion but prevented the increase of the MEPP parameters in the postactivation period. Altogether, the data indicate that an intensive nerve stimulation, which activates neuromuscular junctions and muscle contractions, leads to a release of endogenous CGRP into synaptic cleft and this release strongly depends on the efflux of stored calcium. The released endogenous CGRP is able to exert an acute presynaptic effect on nerve terminals, which involves its specific receptor action and intracellular cascades leading to intensification of ACh loading into synaptic vesicles and an increase in the ACh quantal size.     

Cortical interactions in the beta2-rhythm during examination stress

Two groups of students: with higher and lower amplitudes of the baseline alpha-rhythm differed in the level of anxiety during examinations and the level of cortical interactions. Cognitive tasks were presented in three experimental conditions: before the examinations, immediately after the examinations, and on a usual day of academic semester (control). Subjects with initially higher alpha-rhythm amplitude had lower level of anxiety in a stress situation. Cognitive performance of these subjects before examinations was associated with an increase in the number of functional connections between different cortical areas. In the subjects with initially lower alpha-rhythm amplitude, the level of cortical interactions before examinations was higher, but presentation of the cognitive task led to a decrease in the number of intracortical connections. However, the localization of these connections was task-specific.