[THE EFFECT OF THE WORD FREQUENCY IN RUSSIAN LANGUAGE ON MISMATCH NEGATIVITY (MMN) IN THE EVENT RELATED POTENTIALS (ERP)].

The present study is designed to establish how lexical frequency of Russian words influences the acoustic mismatch negativity (MMN) latency and amplitude. The event related potentials (ERP) were recorded according to the multi-deviant passive odd-ball paradigm by using Russian words with different lexical frequencies and pseudowords. We found that the high-frequency words presentation led to a significantly more pronounced MMN response relative to the low-frequency one. The high-frequency words also evoked an earlier response, indicating more rapid access to a frequently used lexical entry. We suggest that a more pronounced amplitude and an earlier latency of acoustic MMN of high-frequency versus low-frequency items is a result of the word memory traces activation as more strongly connected assemblies of neurons. The MMN amplitude and latency for words were partly matched with the MMN for pseudowords (the analog of high-frequency word evoked the most pronounced response and the analog of low-frequency word evoked the weakest response), but the MMN amplitude and latency for pseudowords were significantly more pronounced and longer. We interpret this as evidence that processing of meaningless or unknown items is longer and their discrimination is more late and inaccurate than the discrimination of meaningful and frequently activated language elements.

[FORMATION OF VISUAL-AUDITORY ASSOCIATIONS IN RECOGNITION OF PHONEMES IN CHILDREN].

In this study, we investigated a question about a possibility to form involuntary auditory-visual associations in children (8-11 yrs) during discriminations of speech sounds (phonemes) when they presented simultaneously with visual stimuli. It was used two types of static images - geometrical figures and images of hand gestures. We judge about the formation of auditory-visual association by behavioral disturbance (reaction time, percentage of wrong reactions during discriminations of phonemes) after changes in experimental protocol viz, partial substitution of preceding pairs of stimuli which were used during training to form auditory-visual associations for the new combinations of previous images and sounds. We find that in research conditions comparatively fast formed pronounced auditory-visual association; however features of response to mismatch stimuli in comparison with adults make to suggest the relative immaturity ofneurons of social perception in children.

[The Effect of Cognitive Load on the Development of Muscle Fatigue].

The aim of our study was to examine the effect of cognitive load on the development of muscle fatigue. Sub- jects performed 250 maximal compressions of a handgrip dynamometer in response to the target acoustic stimulus. Stimuli were presented in three paradigms with different levels of cognitive load: (1) the reaction task with one type of signals (2) the acoustic stimuli recognition task with the 50% target and 50% non-target stimuli, where voluntary attention was involved, (3) the recognition task with the 17% target and 83% non tar- get stimuli, that led to the activation of voluntary and involuntary attention systems. As fatigue indicators amplitude of compression force in response to the target stimulus, the maximum voluntary contraction and rating of perceived exertion were used. Our results showed the reduced level of fatigue in experiment with the activation of voluntary and involuntary attention systems. Moreover, the activation of involuntary attention, accompanied by mismatch negativity in the EEG, enhanced the effect of voluntary attention.

[THE INFLUENCE OF FATIGUE ON THE SENSORY GATING TEMPORAL PARAMETERS].

The aim of the study was to investigate the influence of central fatigue and motor activity on sensory gating characteristics. The P50 component in a standard paired-click paradigm was used as a sensory gating index. The main attention was devoted to the P50 peak latency change in the fatigue development. It was found that the sustained muscle load leading to the fatigue development significantly reduced sensory gating and the P50 peak latency in response to the second stimulus of the pair. This may be due to the inhibitory process suppression underlying the sensory gating in the development of central fatigue.

[Specific characteristics of mismatch negativity in infants].

The mismatch negativity component of auditory event-related potentials was studied in fulI-term infants of the first month of life and adults. Acoustic stimuli with large deviance in passive oddball task were used. Research data revealed distinctive features in morphology and specificity in parameters of positive mismatch component in children at early ages. Contrary to results from adult group infant component was manifested in two positive peaks, greater amplitude and longer latency. A significant positive correlation was observed between infant's conceptual age and amplitude, and significant negative correlation was found between gestation age and latency for this positive component. Results allowed proposing specificity in parameters of infant's positive mismatch component indicated proceeding maturational changes in auditory cortex at early ages.

[THE STUDY OF THE TEMPORAL PROPERTIES OF THE AUDITORY SENSORY TRACE FOR A SHORT DURATION STIMULI USING THE MISMATCH NEGATIVITY].

The present article accesses the dependence of mismatch negativity of the human auditory event related potentials on the length of interstimulus interval. We employed passive oddball paradigm as a presentation method and simple tones were used as stimuli. This study was based on the assumption, that storage time of the memory trace, which is used for generation of mismatch negativity, is dependent on the length of the stimulus itself. As a result, the mismatch negativity was registered for short durations 11 ms stimuli. In such stimuli differences of amplitude of mismatch negativity depending on the length of interstimulus interval were also shown. Yet no such differences were found for stimuli of 20 ms and 30 ms. This result allows us to assume that storage time of memory trace of stimulus is directly proportional to the length of the stimulus itself when short interstimulus intervals are used. However, the increase of stimulus length over certain threshold does not show any changes in the properties of mismatch negativity.

[Correlation between Sensory Gating P50, Mismatch Negativity, and Reaction Time].

This paper is about the correlation pre-attentive processes, such as P50 sensory gating (SG P50) and mismatch negativity (MMN) with each other and with sensorimotor reaction time (RT). SG P50 data were obtained in the standard paired-click paradigm, MMN was measured in the passive odd-ball paradigm sensorimotor reaction time was studied in an active odd-ball paradigm. Was obtained positive correlation sensory gating P50 with amplitude mismatch negativity, amplitude mismatch negativity with sensorimotor reaction time, sensory gating P50 with sensorimotor reaction time.

[The influence of movement's observation on recuperation after physical fatigue].

The study aim was to investigate effects of mental activity, accompanied by mu-rhythm depression, on recuperation after physical fatigue. In a study participants performed 11 one minute bouts of static hand grip intermitted by 2 minutes restpauses. During pauses participants watched video with either dynamic hand grips (biological movements) or deformation of geometric figure (control). Obtained data showed there was a significant depression of mu-rhythm during biological movement's observation. There was significant fatigue of subjects in an exercise with physical activity, but there was no reliable influence of performed mental activity on recovery after fatigue.

[The specificity of children and adolescent eating habits (data for schoolchildren in Moscow and Murmansk)].

Objective of the study is to evaluate the specificity of schoolchildren's eating behavior in the cities of Moscow and Murmansk. Dietary habits of 785 children 10-17 years old residing in two cities--Moscow (222 boys and 221 girls, 14.1 ± 1.9 years old) and Murmansk (183 and 159 correspondingly, 14.1 ± 1.8 years old)--were analyzed. The questionnaire included data on the meals ratio per day, frequency of vegetables and fruit intake, fast-food intake, hot meals, soft drinks, meat, fish and milk intake, usage of school cafeteria, regularity of breakfasts. Parents responded to questions concerning the materialsupport of family and education. It was found that more than half of schoolchildren (64.4%) had meals irregularly (3 times per day or less), only 50.9% received hot meals several times a day. Every third child (31.6%) has insufficient intake of vegetables and fruit, 11.8%--insufficient intake of meat dishes. Only 51.4% of schoolchildren consumed dairy products daily (one or several times a day). At the same time 19.5% of children used fast-food products several times a week or more often, 42.2%--carbonated drinks, and 22.7%--smoked food. Only 45.7% of schoolchildren regularly ate at school caf- eteria; 21.9% did it irregularly and 32.5%--did not attend school canteen at all. There were no significant differences between Moscow and Murmansk children as well as gender differences in the usage of school cafeteria. At the same time only 23.4% of children [26.3% in Moscow and 19.3% in Murmansk (significantly less, p = 0.032)] liked cafeteria food, 38.7% did not like and 37.9% had no certain answer. Less obese children (54.0%) have breakfast everyday than children with normal weight (75.4%, p = 0.019). Children of mothers with high and incomplete high education (89.4%) have more regular meat intake (3-4 times per week or more often) than the children of mothers with secondary, incomplete secondary and secondary special education (81.9%, p = 0.034). Schoolchildren feeding is often irregular, irrational and poorly balanced. Some of examined schoolchildren already had excessive body mass (20.7%), that may lead to metabolic and cardiovascular disturbances in young adult and mature age.

[A combination of dipeptidyl peptidase-4 inhibitor and metformin in the treatment of patients with type 2 diabetes mellitus: effective control of glycemia, weight, and quantitative body composition].

AIM: To study the impact of intensified therapy with the dipeptidyl peptidase-4 (DPP-4) inhibitor vilagliptin or sulfonylurea (SU) on the control of glycemia, weight, and quantitative body composition in patients with type 2 diabetes mellitus (DM-2) who have failed to achieve compensation during metformin monotherapy. SUBJECTS AND METHODS: Forty patients (mean age 55.0 (range 53.0-60.7) years; disease duration 2.0 (range 1.1-5.0) years) with poor glycemic control (7%

[Estimation of prosthodontic treatment results in dyscirculatory encephalopathy patients].

The interrelation between cerebral blood circulation and oral diseases as well as impact of prosthodontics treatment on cerebral hemodynamics was examined in the study. Cerebral hemodynamics was assessed by transcranial Doppler in 75 patients divided into three groups: (1) 30 patients with the initial form of vascular cerebral disorders (stage I-II); (2) 25 patients with severe vascular cerebral disorders (stage III); (3) 20 persons with no signs of encephalopathy as control group. Prosthodontic rehabilitation by full and partial teeth loss proved to contribute to normalization of indices of cerebral blood flow in patients with initial forms of cerebrovascular insufficiency (I and II stage of encephalopathy) and in patients with acute forms of insufficient brain blood supply (II and III stage of encephalopathy).

[Relationship between carotid artery intima media thickness and risk factors of cardiovascular diseases in young men].

Positive correlation between age, leading risk factors of cardiovascular diseases (CVD), and carotid artery intima-media thickness (IMT) has been shown in numerous studies. Contingent of the present work was a part of long term cohort study initiated in 1983. We included in analysis data from 233 men in 120 of whom we measured IMT of right and left common carotid arteries. Other examinations included use of standard questionnaire for detection of CVD risk factors, measurement of blood serum lipid and glucose levels, arterial pressure, pulse, body mass and length, waist and hip circumferences (WC, HC), skin fold thicknesses on triceps, abdomen and forearm. We found that carotid artery IMT was related to hereditary load by CVD along paternal line. Substantial influence on the realization of unfavorable inheritance exerted level of systolic arterial pressure. Difference in magnitude of carotid artery IMT between groups of men with normal body mass and obesity were conditioned by variations in severity of abdominal obesity (WC/HC). IMT of carotid arteries in men directly depended on magnitude of their abdominal obesity and age.

[Assessment of risk of cardiovascular diseases in persons of young age].

Cardiovascular pathology appears to be big socially meaningful problem as it occupies leading place in structure of mortality and loss of working capacity in economically developed countries. Social value of the problem is enforced by observed in recent years tendency to increase of mortality of cardiovascular diseases (CVD) in young age persons. It has been shown in large prospective studies that traditional CVD risk factors such as sex, lipid spectrum of blood, smoking, arterial hypertension, obesity, and hyperglycemia correlate with pathologoanatomical findings of atherosclerotic plaques in coronary arteries and abdominal aorta of young people aged 15-34 years. Proper and well-defined stratification of risk in young people will allow to approach solution of the problem of morbidity and mortality in older age. This work contains data on results of prospective multicenter epidemiological and clinical studies devoted to investigation of established and novel risk factors in the young, their contribution to development of atherosclerotic process, morbidity and mortality caused by CVD in later age. We also analyze prognostic potential of existing at this moment in the world scales for assessment of cardiovascular risk specifically in this group of population, and present data on prognostic models created specially for assessment of CVD risk in persons of young age.

[Changes of the micro-rhythm in different forms of motor activity and movement observation].

When presenting the subjects with video-records of different forms of movements, a moderate suppression of spectral power occurs in the micro-rhythm range. Analysis of temporal suppression of the micro-rhythm revealed that the changes obvious enough at the beginning of the observation became gradually weaker, and at the final stages dropped to statistically insignificant values. This habituation effect for the micro-rhythm changes indicates a possible role of the mechanisms of involuntary and voluntary attention in the micro-rhythm depression.

[Occurrence of discoordination negativity in response to changes in duration of short pause against the background of continuous auditory stimulation].

Mismatch negativity (MMN) is a component of the auditory event-related brain potential which is widely used both in basic and clinical research. With the traditional oddball paradigm we obtained an MMN-like response that changed in duration of the silent gaps (standard 25 ms, deviant 50 ms and vice versa) in continuous auditory stimulation (1 kHz, 50 dB). To our knowledge, this is the first report of such a type of MMN. This response was compared to "classical" MMN elicited by duration change of sound of the same temporal characteristics. MMN in response to gap duration change differed in a shorter latency and had no polarity reversal at the mastoids. Both for sounds and gaps, when the deviant was longer than the standard, we observed a shorter latency of MMN response than in the reversed setup. We believe that use of the ERR and MMN techniques in a new paradigm of short gaps interrupting continuous sound stimulation might help to shed some light on the mechanisms of auditory information processing in the auditory system, as well as to bring deeper insight in understanding of MMN nature itself, and, possibly, to find some new clinical or fundamental applications.

Mismatch negativity: the contribution of differences in the refractoriness of stimulus-specific neuron populations.

Mismatch negativity (MMN) is a component of auditory evoked potentials associated with rare changes in acoustic stimulation. Mismatch negativity is usually interpreted as an automatic response from a "changes detector" based on comparison of an incoming stimulus and the representation of preceding stimulation in memory. However, some investigators take the view that mismatch negativity is explained by simpler processes, associated with neuronal refractoriness. The existence of "genuine" mismatch negativity was confirmed, though the question of the contribution of refractoriness to traditional mismatch negativity remained open. The present study uses an experimental design allowing the hypothetical sources of mismatch negativity to be discriminated. A contribution to mismatch negativity associated with neuronal refractoriness was demonstrated; this decreased with increases in the probability of presentation of a deviant stimulus and became negligible at a probability of 15%. Thus, classically interpretable mismatch negativity can be obtained either by using a method excluding the contribution of refractoriness or by using "safe" deviant stimulus presentation probabilities.

[Experimental formation of visual-auditory associations in phoneme recognition].

In this study we investigated a question about a possibility to form auditory-visual associations during discrimination of speech sounds (phonemes) when they presented simultaneously with visual stimuli. It was used two types of static images--geometrical figures and images of hand gestures. We judge about formation of auditory-visual association by behavioural disturbance (reaction time, percentage of wrong reactions) after changes in experimental protocol viz. partial substitution of preceiding pairs of stimuli for the new combinations of previous images and sounds. It seems possible to get pronounced auditory-visual association when using images of hand gestures in combinnation with phoneme sounds. On the contrary, employment of images of geometrical figures instead of gestures produced only traces of auditory-visual association. We suggest that it is possible to explain the observed differencies by involvement of additional neuronal populations in auditory-visual assosiation that are preferentially responsive to biological motion.

[Mismatch negativity: contribution of difference in refractoriness of stimulus-specific neuronal populations].

Mismatch negativity (MMN) is a component of auditory evednt-relate brain potential (ERP) relate to any occasional change in auditory stimulation irrespective of subject's attention. It is believed to reflect an automatic response of specialized change-detector based on comparison of incoming stimulus with memory trace of preceding stimulation. But there is an alternative point of view that MMN might simply arise from difference in neuronal refractoriness. Existence of genuine MMN was proved but the issue of refractoriness contribution still remains open. In this study, we used experimental design allowing separation of the hypothetical MMN sources. Significant refractoriness-related contribution to the traditional MMN has been shown. This contribution decrease along with deviant occurrence probability increase becoming negligible by 15 % probability. We suggest that either refractoriness controlling experimental design or safe deviant probability is to be used to obtain traditionally interpreted MMN.

[Use of polymerase chain reaction for the diagnosis and evaluation of chemotherapy for pulmonary tuberculosis].

Polymerase chain reaction (PCR) using a new procedure for preparing sputum samples for DNA isolation on the basis of immunomagnetic separation of mycobacteria was employed to examine sputum samples from 141 patients with first diagnosed pulmonary tuberculosis and 510 diagnostic materials from patients with nonspecific lung disease. In 47 patients with pulmonary tuberculosis, sputum bacterial isolation was followed up, by using PCR and conventional microbiological studies during regular, every 6-7-week, examination. The sensitivity of PCR employing the above procedure for preparing the samples averaged 66% versus 48% when a cultural study was applied. Its specificity was 99.4%. Bacterial isolation cessation with the use of PCR well correlated with the clinical and X-ray trends in the disappearance of the signs of a tuberculous process.

[Cardiorenal pathology in diabetes mellitus type 1: mechanisms of development and medical correction].

AIM: To elicit the role of endothelial dysfunction in development of cardiorenal syndrome in patients with diabetes mellitus type 1 (DM1) with diabetic nephropathy (DN) and to evaluate the efficacy of endotheliotropic drugs: nebivolol (a selective beta-blocker) and enalapril (ACE inhibitor). MATERIAL AND METHODS: The trial enrolled 60 patients with DM1: 15 patients with normoalbuminuria (NAU), 15 patients with microalbuminuria (MAU), 15 patients with proteinuria (PU) and 15 with chronic renal failure (CRF). The control group consisted of 15 healthy volunteers matched by sex and age. All the patients were examined for endothelium-dependent dilation of the brachial artery (by duplex scanning in the test with reactive hyperemia), serum markers of endothelial dysfunction (endothelin-1--ET-1), Willebrand factor (WF), inflammation markers (C-reactive protein-CRP), incidence rate of ischemic heart disease (IHD). 24-h arterial pressure monitoring and echocardiography were also made. For 12 weeks the patients were given nebivolol monotherapy in a dose 5 mg/day or enalapril monotherapy in a dose 10 mg/day. The effects of these drugs on urinary excretion of albumin and protein, arterial pressure, circadial rhythm of arterial pressure and endothelial dysfunction were studied. RESULTS: In DM1 patients DN advances with an increase in development of IHD: in MAU--by 13%, PU--by 33%, CRF--53%. Concentric hypertrophy and left ventricular remodeling were registered in 33, 40 and 60% of cases, respectively. A circadian rhythm disturbance correlated with DN severity. DN progression was associated with increasing endothelial dysfunction. It is shown that nebivolol and enalapril correct endothelial dysfunction, have comparable antiproteinuric and antihypertensive actions at different stages of nephropathy. CONCLUSION: A close correlation was found between DN progression and development of cardiovascular pathology in DM1 patients. This serves the basis of cardiorenal syndrome. These two pathologies are associated with vascular endothelial dysfunction which leads to disorders in vascular tonicity regulation.