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Background: Stress at workplace arises when the requirements for workers don’t meet their personal or social capabilities, or differ from the individual’s needs and motivation. Occupational stress is observed in a number of both elementary and high-tech occupational fields. In ferrous metallurgy it could be associated with 24/7 operating mode, high work intensity and a variety of unfavorable characteristics of working environment. The aim of the study is to clarify the nature of factors - stressors in ferrous metallurgy and to define ways for reduction of their negative health impact. Materials and Methods: Study subject are 91 workers in an electric steel-making department of a ferrous metallurgy enterprise in Bulgaria. Data, concerning working conditions, work characteristics, workers satisfaction, presence/absence of stress and chronic diseases, were collected by direct individual self-administered questionnaire and documents review. Results: Two of three study subjects reported stress related to their work. Noise, varies from 89.2 to 92.2 dB/A (at rate 85 dB/A) in different sections of the workshop, is the biggest stressor according to 77.5% of the investigated people, followed by short deadlines for task performance (46.5%) and ineffective leadership (32.4%). In addition, negative effects of stress is increasing by high dust levels, reaching up to 7 mg/m3 air at a standard of 6 mg/m3 air, and contain manganese, coke, chamotte, free and bound silica, rare metals, increased concentration of CO and more.Nevertheless workers consider that the organization provides measures for stress reduction by strict control on the limit values of noise, dust, temperature and chemicals (49.2%),provision of personal protective equipment establishment (69%) of a rational mode of work and rest (56.3%) and healthy eating (47.9%). Conclusions: Despite a plenty of environmental and organizational stressors, their negative effects could be decreased by appropriate preventive measures. Key messages: ) Factors-stressor in ferrous metallurgy could be associated with a variety of unfavorable characteristics of working environment,non-stop operating mode, high work intensity and poor time management. ) Noise is the biggest stressor followed by short deadlines for task performance and ineffective leadership. Stressors are modifiable and preventable by strict hygienic control and improved management. [ABSTRACT FROM AUTHOR]

Abstract: The ability of the fungus Aspergillus awamori NRRL 3112 to degrade mixtures of some common phenolic compounds, namely phenol, catechol, 2,4-dichlorphenol and 2,6-dimethoxyphenol was investigated in the present study. For all combinations in which dichlorophenol was incorporated, it took equal time for the nearly complete degradation of the compound—4 days. Phenol was decomposed almost completely (99.5%) in a combination with dimethoxyphenol, to a lesser extent (88%) in a combination with catechol and to the least degree (25%) in the presence of 2,4-dichlorophenol. Catechol experienced a more substantial biotransformation (64%) when mixed with phenol and weaker (45%)—in a combination with dichlorophenol. 2,6-Dimethoxyphenol was better decomposed (69%) in mixtures containing phenol, while its biodegradation in a combination with 2,4-dichlorophenol was considerably poor (only 5%). [Copyright &y& Elsevier]

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by a dysfunction of the immune system. Mesenchymal stromal cell (MSCs) derived extracellular vesicles (EVs) are nanometer-sized particles carrying a diverse range of bioactive molecules, such as proteins, miRNAs, and lipids. Despite the methodological disparities, recent works on MSC-EVs have highlighted their broad immunosuppressive effect, thus driving forwards the potential of MSC-EVs in the treatment of chronic diseases. Nonetheless, their mechanism of action is still unclear, and better understanding is needed for clinical application. Therefore, we describe in this review the diverse range of bioactive molecules mediating their immunomodulatory effect, the techniques and possibilities for enhancing their immune activity, and finally the potential application to SLE., Competing Interests: CW and TF are employed by EVerZom. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Wong, Stoilova, Gazeau, Herbeuval and Fourniols.)

In the present study, the chemical composition and antioxidant potential of an essential oil of ginger rhizomes from Ecuador was elucidated. The analysis of the essential oil by GC/FID/MS resulted in identification of 71 compounds, of which the main are citral (geranial 10.5% and neral 9.1%), α-zingiberene (17.4%), camphene (7.8%), α-farnesene (6.8%) and β-sesquiphellandrene (6.7%). The in vitro antioxidant activity of the essential oil expressed by IC50 in descending order is: hydroxyl radical (OH*) scavenging (0.0065 μg/mL) > chelating capacity (0.822 μg/mL) > 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid radical cation (ABTS*+) scavenging (3.94 μg/mL) > xanthine oxidase inhibition (138.0 μg/mL) > oxygen radical (O2*) scavenging (404.0 μg/mL) > 2,2- diphenyl-1-picrylhydrazyl radical (DPPH*) scavenging (675 μg/mL). Lipid peroxidation inhibition of the essential oil was less efficient than butylhydroxytoluol (BHT) in both stages, i.e. hydroperoxide and malondialdehyde formation. In vivo studies in Saccharomyces cerevisiae demonstrated a significant dose-dependent increase in antioxidant marker enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), blocking the oxidation processes in yeast cells. Moreover, ginger essential oil in concentrations of 1.6 mg/mL increases the viability of cells to oxidative stress induced by H2O2.

The essential oil of juniper berries (Juniperus communis L., Cupressaceae) is traditionally used for medicinal and flavoring purposes. As elucidated by gas chromatography/flame ionization detector (GC/FID) and gas chromatography/mass spectrometry (GC/MS methods), the juniper berry oil from Bulgaria is largely comprised of monoterpene hydrocarbons such as α-pinene (51.4%), myrcene (8.3%), sabinene (5.8%), limonene (5.1%) and β-pinene (5.0%). The antioxidant capacity of the essential oil was evaluated in vitro by 2,2-Diphenyl-1-picrylhydrazyl (DPPH) scavenging, 2,2-azino-bis-3-ethylbenzothiazoline-6 sulfonic acid (ABTS) radical cation scavenging, hydroxyl radical (ОН(•)) scavenging and chelating capacity, superoxide radical ((•)O₂(-)) scavenging and xanthine oxidase inhibitory effects, hydrogen peroxide scavenging. The antioxidant activity of the oil attributable to electron transfer made juniper berry essential oil a strong antioxidant, whereas the antioxidant activity attributable to hydrogen atom transfer was lower. Lipid peroxidation inhibition by the essential oil in both stages, i.e., hydroperoxide formation and malondialdehyde formation, was less efficient than the inhibition by butylated hydroxytoluene (BHT). In vivo studies confirmed these effects of the oil which created the possibility of blocking the oxidation processes in yeast cells by increasing activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx).

The chemical composition of the essential oil from peppermint (Mentha x piperita L.) was analyzed by GC/FID and GC-MS. The main constituents were menthol (40.7%) and menthone (23.4%). Further components were (+/-)-menthyl acetate, 1,8-cineole, limonene, beta-pinene and beta-caryophyllene. Peppermint oil possessed antiradical activity with respect to DPPH (diphenyl picryl hydrazyl) and hydroxyl (OH*) radicals, exercising stronger antioxidant impact on the OH* radical. The concentrations required for 50% inhibition of the respective radical (IC50) were 860 microg/mL for DPPH and 0.26 microg/mL for OH*. Peppermint essential oil demonstrated antioxidant activity in a model linoleic acid emulsion system in terms of inhibiting conjugated dienes formation by 52.4% and linoleic acid secondary oxidized products generation by 76.9% (at 0.1% concentration).

The chemical composition of the essential oil from cornmint (Mentha canadensis L.) was analyzed by GC/FID and GC-MS. The main constituents were menthol (41.2%) and menthone (20.4%). It was established that cornmint oil had antiradical activity with respect to the DPPH and hydroxyl (OH*) radicals. The concentrations necessary for 50% neutralization of the respective radicals (IC50) were 365.0 microg/mL for DPPH and 0.3 microg/mL for OH*, which was indicative that the antioxidant activity in terms of OH* was higher than that of quercetin. Cornmint oil chelated the Fe3+ ions present in the solution. The oil demonstrated antioxidant activity in a linoleic acid emulsion model system, where at 0.1% concentration it inhibited the formation of conjugated dienes by 57.1% and the generation of secondary oxidized products of linoleic acid by 76.1%.

Dynamic analysis of arterial blood pressure in relation to the Earth's magnetic field perturbations was performed in 77 practically healthy volunteers (staff of Bulgarian Academy of Sciences). Almost half of them proved magneto-sensitive, i.e. experienced AP elevation with increased geomagnetic activity. The probability of development of magnetic sensitivity was independent of age and gender but increased in volunteers having even mild cardiovascular pathology. These subjects complained of worsened health condition upon a rise in geomagnetic activity. However, some volunteers reported deteriorated well-being without AD elevation. It means that AD measurement may be insufficient for reliable monitoring magnetic sensitivity.

The biodegradation process of high catechol concentrations by Aspergillus awamori was investigated. The values of the kinetic constants for a model of specific growth rate at different initial conditions were determined. At 1.0 g/L catechol concentration, the biodegradation process proceeded in the conditions of substrate limitation. At higher catechol concentrations (2.0 and 3.0 g/L) a presence of substrate inhibition was established. The dynamics of the specific catechol degradation rate was studied and the values of catechol and biomass concentrations, maximizing the specific catechol degradation rate, were estimated analytically. The specified ratio catechol/biomass could serve as a starting base for determination of the initial conditions for a batch process, for specifying the moment of feeding for a fed-batch process, and for monitoring and control of a continuous process by the aim of time-optimal control.

The growth and the enzymatic production of two microbial fungal associations were studied: Aspergillus niger and Fusarium moniliforme and Trametes versicolor and Aspergillus niger. The synergistic interrelations between the species of the first mixed culture increased the biosynthesis of alpha-amylase and pectinase. T. versicolor and A. niger proved to be compatible partners in the overproduction of the enzyme laccase, whose synthesis surpassed 8.4 times the enzymatic level in the monoculture, with both of the mixed microbial populations cocultivation facilitating the amplified synthesis of enzymes rather than their growth acceleration. A further proof of the presence of synergism established by the cultures was the enzyme volumetric productivities in both of the mixed microbial cultures, which increased parallel to the rise in the combined biomass synthesis. The competent selection of compatible partners can adjust the desired enzymatic levels and compositions in mixed fungal systems aimed at a number of specified designations. Thus, a very high level of laccase production (97,600 IU/g dry weight) was achieved. The chosen fungal strains produce a variety of different enzymes, but first microbial association produces mainly amylase and pectinase, necessary for their growth, and second association produces mainly laccase and pectinase.

The antioxidant activity of a commercial rectified clove leaf essential oil (Eugenia caryophyllus) and its main constituent eugenol was tested. This essential oil comprises in total 23 identified constituents, among them eugenol (76.8%), followed by beta-caryophyllene (17.4%), alpha-humulene (2.1%), and eugenyl acetate (1.2%) as the main components. The essential oil from clove demonstrated scavenging activity against the 2,2-diphenyl-1-picryl hydracyl (DPPH) radical at concentrations lower than the concentrations of eugenol, butylated hydroxytoluene (BHT), and butylated hydroxyanisole (BHA). This essential oil also showed a significant inhibitory effect against hydroxyl radicals and acted as an iron chelator. With respect to the lipid peroxidation, the inhibitory activity of clove oil determined using a linoleic acid emulsion system indicated a higher antioxidant activity than the standard BHT.

Beta-galactosidases (beta-D-galactoside-galactohydrolases (EC 3.2.1.23), lactases) are important industrial enzymes used for the hydrolysis of lactose from milk and milk whey. These enzymes are produced by different organisms and purified by multi-step procedures. The multi-step purification schemes are cost and time ineffective which can also lead to poor yield, denaturation and loss of enzymatic activity. In our study, extracellular beta-galactosidase from mutant strain Aspergillus oryzaeH26-10-7 was purified by a two step procedure, Metal-ion Affinity Chromatography (IMAC) followed by size-exclusion separation. Purified enzyme was characterized by sodium dodecyl Sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and zymographic analysis. This fungal beta-galactosidase was characterized as a protein corresponding to 113 kDa. Enzyme from mutant strain was found to have five times higher catalytic activity on the synthetic substrate o-nitrophenyl-beta-D-galactopyranoside (ONPG) compared to the wild type enzyme. Moreover, the mutant enzyme was more thermo resistant compared to the wild type. This highly important technological characteristic can be exploited in food industry. Moreover, based on the IMAC patterns of wild type and mutant enzymes, similarities in their His topography were supposed., (Copyright 2006 John Wiley & Sons, Ltd.)

This study attempts to assess the influence of local geomagnetic storms at middle latitudes on some human physiological parameters. The blood pressure (bp), heart rate and general well-being of 86 volunteers were measured, the latter by means of a standardised questionnaire, on work days in autumn, 2001 (1 Oct to 9 Nov), and in spring, 2002 (8 April to 28 May). These timespans were chosen as periods of maximal expected geomagnetic activity (GMA). Altogether, 2799 recordings were obtained and analysed. A four factor analysis of variance (MANOVA) was employed to check the significance of the influence of four factors (local GMA level; sequence of the days of measurements covering up to 3 days before and after geomagnetic storms; sex and the presence of medication) on the physiological parameters under consideration. Post hoc analysis was performed to elicit the significance of differences in the factors' levels. Arterial bp was found to increase with the increase of the GMA level, and systolic and diastolic bp were found to increase significantly from the day before till the second day after the geomagnetic storm. These effects were present irrespective of sex and medication.

The authors investigated the effects of local and planetary geomagnetic activity on human physiology. They collected data in Sofia, Bulgaria, from a group of 86 volunteers during the periods of the autumnal and vernal equinoxes. They used the factors local/planetary geomagnetic activity, day of measurement, gender, and medication use to apply a four-factor multiple analysis of variance. They also used a post hoc analysis to establish the statistical significance of the differences between the average values of the measured physiological parameters in the separate factor levels. In addition, the authors performed correlation analysis between the physiological parameters examined and geophysical factors. The results revealed that geomagnetic changes had a statistically significant influence on arterial blood pressure. Participants expressed this reaction with weak local geomagnetic changes and when major and severe global geomagnetic storms took place.

Sleep problems have been observed during many of the space flights. The existence of poor quality of sleep, fatigue, insomnia or different alterations in sleep structure, organization and sleep cyclicity have been established. Nevertheless results obtained from investigations of human sleep on board manned space vehicles show that it is possible to keep sleep patterns related to the restorative and adaptive processes. For the first time in the frame of the "Intercosmos" program a multi-channel system for recording and analysis of sleep in space was constructed by scientists of the Bulgarian Academy of Sciences and was installed on board the manned Mir orbiting station. In 1988 during the joint Bulgarian-Russian space flight continues recording of electro-physiological parameters necessary to estimate the sleep stages and sleep organization was made. These investigations were continued in next space flights of different prolongation. The results were compared with the findings obtained under the conditions during the pre- and post-flight periods., (c2003 COSPAR. Published by Elsevier Science Ltd. All rights reserved.)

The heart rate (h.r.) of normal healthy subjects varies in rest, under high-load conditions and in pathology. The heart rate variability (h.r.v.) integrates many mechanisms in- and outside the central nervous system, which influence and regulate the h.r. Statistical methods have been used to obtain additional information concerning the diagnostic capabilities h.r.v., the correlation between ECG R-R intervals and their variability and the prognostic significance of h.r.v. The benefits of modification of h.r.v. are not well known. In our previous study the h.r.v. of astronauts before, during and after long-term space flight (seven months) was examined. In this study we make analysis of h.r.v. in wake and sleep in different phases during a short-time space flight (9 days) of the Bulgarian astronaut A.A. in 1988.

The course of different sleep phases has been studied in group of patients. A decrease in duration of deep sleep phase and increase in the number of awakenings are found in them.

In 40 aquanauts, a prolonged stay under increased pressure (11 to 46 kgs/cm2) of the oxygen-helium-nitrogen mixture did not affect the average duration of sleep. Slow-wave sleep, mostly its 3 rd and 4 th stages, and paradoxical sleep were significantly decreased whereas the light sleep/profound sleep ratio increased. The cyclic structure of sleep became altered. The longer the exposure to high pressure led to an augmentation of the slow-wave sleep and REM-phase, but the normal cycles terminating with a REM-phase could not be formed during the experiment.

Changes of amplitude-temporal parameters of visual evoked potentials (VEPs) under hyperbaric action testify to reconstruction of the activity of functional brain systems participating in the generation of responses to light stimulation. The revealed EP changes depend both on conditions of hyperbarism and on individual characteristics of subjects. The parameters of VEPs may manifest the estimation of common functional state under prolonged extreme influences.

Spectral correlation methods of EED-analysis were used to study the local synchronization (by power spectra--FFT) and the spatial synchronization (by assessing the coherence functions) of the cortical electrical activity of persons subjected to prolonged (one-month) extreme impact--hyperbaric conditions. Two neurophysiological mechanisms of system functional organization of the electrical activity of the central nervous system are described, through which the brain compensates its reduced functional capacities under the extreme conditions studied (including boundary physiological states). These mechanisms: (a) act in almost all situations of the extreme impact, irrespective of the scope of the remaining varied transient or lasting readjustments in the EEG, and (b) guarantee spatial interactions in the electrical activity in the brain in frequency ranges which are essential for its functions: alpha (8-12 Hz) and beta-2 (24-36 Hz).

A modification of an apparatus for undirect bloodless measurement of the arterial blood pressure (BP) in the tail of small laboratory animals (rats) is described. The device consists of a 3-channel ECG apparatus (C3a), connected with a blood pressure recorder(R67z/32) with an osciliscope (R17e) for visual checking of blood pressure. Criteria as well as possibility for measuring not only the systolic, but also the diastolic level of the blood pressure are indicated due to the great sensitivity of the device. It is pointed out that the coefficient of variation (3,58% for the systole and 5,95% for the diastole) is very low which confirms the reliability of the method. The results of a continuous (12 months) dynamic follow-up of the systolic and diastolic blood pressure of normotensive (NWR) and spontaneously hypertensive rats (SHR) are also reported. The authors conclude that the results could be used as normatyves and as indices for the range of the systolic and diastolic blood pressure of NWR and SHR aged 1 to 12 months, since no data about the diastolic blood pressure of rats are available so far in the literature.

With the method of isotope dilution the circadian cortisol secretion was determined in 22 patients with hypertonic disease--28.35 mg/24 h, elevated versus CSR in healthy subjects-16.63 mg/24 h. CSR is elevated also in 5 patients with bilateral adenocortical hyperplasia and with suprarenal cancer. The patients with diencephalic syndrome, progressing according to the type of Cushing disease have elevated absolute values of CSR, but recalculated per square meter of body surface and per gram creatineine excreted in 24 h-CSR proved to be normal-about 12 mg/24 h.

The total non-conjugated plasma cortisol in 60 patients with hypertension disease (HD)is 17.5 mkg/ml. The free non-conjugated cortisol represents 8.45 per cent of the total - 1,5 mkg%, considerably (p less than 0.0001) higher than that in healthy subjects. Protein conjugated cortisol is 16.0 mkg%. The bounding capacity of transcortin the plasma of hypertonics is considerably decreased (p less than 0.0001) - 15.8 mkg (in healthy - 18.5 mkg) per 100 ml. ACTH level in the plasma of patients with HD is 32.0 pg/ml, considerably higher than that in healthy (25.8 pg/ml, p less than 0.0001). The elevation of the biologically active cortisol fraction in plasma of hypertonics is a function both of hypothalamo-hypopheseal stimulation and of transcortin level. That latent hypercortisolism is admitted to be manifestation of hypothalamo - hypopheseal superstimulation by increased ACTH secretion, in case of confirmed cerebro-hypothalamic disturbances in patients with hypertension disease.