[The hygienic ergonomic protection of speech communication over time]. / Khigieno-ergonomichna zashtita na rechevata komunikatsiia s vremeto.

In the course of the experimental laboratory studies it was found out a significant impairment of the communication following a 2-hour processing of speech signals in conditions of masking noise. In order to diminish the auditory exhaustion in impeded communication the authors created physiologically grounded model of the working and resting regime in accordance to the experimental data, which require the including of two breaks in the first half of the working day, i.e. after a two hour exposition to masking noise. The minimal duration of the break at the end of the second hour (according to the experimental data) must be not less than 10 minutes in order to reach the initial or near to it speech communication. The time of the second break may coincide with the regulated lunch-time. The created working and resting regime was approbated in working conditions at DF "Kremikovtsi". It was found out that following the introduction of the physiological regime of work and rest, the auditory exhaustion decreased which was expressed in lowering of the rate of tone-intensity steps.

[Age-related transfer coefficients of the basic indices of cardiac variance]. / Vuzrastovi prevodni koefitsienti na osnovni pokazateli na surdechnata variativnost.

This study was concerned with the relationship of changes in cardiac variance to age. A total of 518 subjects were involved. The following indicators of ACV (analysis of cardiac variance) were investigated: mean--mean value of successive cardiac intervals, SD--standard deviation of mean value of cardiac intervals (R-R), AMo--amplitude of the mode, HI--homeostatic index, Pt--spectral power of R-R related to thermoregulation, Pr--spectral power of R-R related to respiration, IBO--index of centralization. For each one of these ACV indicators, a mathematical expression of its relationship to age was specified. The coefficients obtained from the indicated expressions of the relationship "age-to-ACV indicators" represent transfer coefficients for the particular measured quantities. Their methodological importance lies in the fact that through them it becomes possible to make age corrections of ACV indicator figures for the purpose of comparing individual subjects or groups of subjects. These coefficients help to establish nomograms for the particular age ranges.

[Changes in the status of the adaptation of workers at the television relay station on top of Botev Peak]. / Promeni v sustoianieto na adaptatsiia na raboteshti ot televizionnata retranslatsionna stantsiia na vrukh "Botev".

The state of adaptation of subjects (numbering 17) occupied at Botev Peak TV relay station and thereby exposed to nonionizing radiations--electromagnetic fields (EMF)--was monitored by following changes in analysis of cardiac variance (ACV) indicators. In addition to these, other physiologic indicators studied were systolic and diastolic blood pressure, as well as psychologic indicators, notably, psychosomatic complaints as early manifestations of disturbance in the state of adaptation. Data from the group of subjects studied were compared to those of a control group whose working conditions involved no EMF exposure. This comparison, based on ACV indicators (mean--mean value of successive cardiac intervals, SD--standard deviation of mean value of cardiac intervals (R-R), AMo--amplitude of the mode, SI, ABI, HI--homeostatic index, CP--classification parameter, IC), psychosomatic complaints, systolic and diastolic blood pressure, provided no evidence of reduction of adaptive reserves or deterioration of somatic and mental health state in occupationally exposed workers at Botev Peak TV relay station.

[The correlations between psychological indices and cardiac variance]. / Korelativni zavisimosti mezhdu niakoi psikhologichni pokazateli i surdechnata variativnost.

Correlative links between psychologic and psychologic indicators were studied in subjects occupied either in airline transportation or in the chemical industry. Investigations covered three groups of persons: managers of airline traffic (57 subjects); workers at "Vratsa" Chemical plant (14 subjects); and operators at "Vratsa" Chemical plant (14 subjects). The psychologic parameters measured included indicators of cardiac variance: mean--mean value of successive cardiac intervals, SD--standard deviation of mean value of cardiac intervals (R-R), AMo--amplitude of the mode, HI--homeostatic index, Pt--spectral power of R-R related to thermoregulation, Pp--spectral power of R-R related to respiration, IBO--index of centralization; psychologic parameters included: extrovertiveness, introvertiveness, neuroticism, psychoticism, interpersonality conflicts, self-control, social support, self-confidence, work satisfaction, psychosomatic complaints. There was evidence of significant and highly significant correlative links between indicators of cardiac variance and psychologic indicators. There thus appeared to exist certain relationships between the psychologic and psychologic levels during lengthy stressful occupational exposure.

[Changes in the frequency spectrum of the heart rhythm under static muscular effort]. / Promeni v chestotniia spektur na surdechniia ritum pri statichno muskulno usilie.

Certain results are gives which show that the frequency spectrum of the heart rhythm during the fulfillment of static muscle effort to refusal, distinguishes significantly the way in which this test is performed by experienced persons: at complete motivation (physiological refusal) and in incomplete motivation (psychological refusal). The second type of answer is unwanted in practical application of the test in industry, that's why a conclusion is made, that the frequency spectrum of the heart rhythm could serve as criterium of correctness for putting the test into practice.

[An electroneurographic study of agricultural workers working with organophosphate pesticides]. / Elektronevrografsko izsledvane na selskostopanski rabotnitsi pri rabota s fosfororganichni pestitsidi.

An electroneurographic method is used for examining 60 agricultural workers at the beginning and the end of the season of spraying with organophosphorus pesticides. At the end of the season (in comparison with the beginning a significant increase of the amplitude of the evoked potential is established as well as a decrease in the velocity of performance at stimulating the motor fibres of n. medianus, and in the velocity of conducting of n. peroneus. The electroneurographic method could be used with success for monitoring the effects of exposure to organophosphorus pesticides.

[Epidemiological studies of the effect of organophosphate pesticides on health]. / Epidemiologichno izsledvane v'rkhu zdravnite effekti na fosfororganichnite pestitsidi.

The subject of study are agricultural workers applying organophosphorus and other pesticides in an area with intensive agriculture and a control group from the same area having no professional contact with pesticides. The studies include: personal and professional anamnesis, a battery of neurobehavioral tests, electroneuromyography, evoked potentials, neurological status, internal status, hematological tests, liver enzymes, variability of the heart rhythm. The level of the exposure is assessed by: measuring the concentration of PhO compounds in the air of the work environment and deposit on the skin. The biological monitoring is carried out by measuring the level of the cholinesterase activity in serum and erythrocytes, neuropathy target esterase in lymphocytes and alkylphosphates in urine. The tests are performed before and after the active season of spraying. The results from the studies show that at continuous exposure to low concentrations of organophosphorus compounds, applicated in agriculture, no significant health disorders occur. Specific deviations are observed after the season of spraying in the neuro-behavioural tests as increasing the number of incorrectly put dots in the Aiming test, the time of reaction and evoked potentials. The interpretation of the results is impeded because of the large number of interfering factors and considerable quantity of alcohol.

[Effect of +Gx acceleration and adeturon on the nucleic acid content and other indices of the peripheral blood of mice]. / Vliianie uskoreniia +Gx i adeturona na soderzhanie nukleionovykh kislot id drugie pokazateli perifericheskoi krovi u myshei.

The effect of acceleration and adeturon, a radioprotector, on the content of nucleic acids, the count, composition and osmotic resistance of white and red blood cells was investigated. Male mice of the H strain were exposed to +20 Gx for 5 min. The above parameters were measured 1, 24 and 48 hrs after the exposure. The nucleic acid content decreased significantly immediately after the exposure and tended to return to normal afterwards. The leucocyte count was increased during all observation periods, and the erythrocyte count was decreased 1 hr after the exposure. Osmotic resistance of white and red blood cells varied in a different manner after the exposure. Adeturon administered at optimal protective doses (300 mg/kg) modified regulatory mechanisms of the animal body.