How do employment conditions and psychosocial workplace exposures impact the mental health of young workers? A systematic review.

PURPOSE: To assess the quality of the research about how employment conditions and psychosocial workplace exposures impact the mental health of young workers, and to summarize the available evidence. METHODS: We undertook a systematic search of three databases using a tiered search strategy. Studies were included if they: (a) assessed employment conditions such as working hours, precarious employment, contract type, insecurity, and flexible work, or psychosocial workplace exposures such as violence, harassment and bullying, social support, job demand and control, effort-reward imbalance, and organizational justice; (b) included a validated mental health measure; and (c) presented results specific to young people aged ≤ 30 years or were stratified by age group to provide an estimate for young people aged ≤ 30 years. The quality of included studies was assessed using the Risk of Bias in Non-randomized Studies of Exposures (ROBINS-E) tool. RESULTS: Nine studies were included in the review. Four were related to employment conditions, capturing contract type and working hours. Five studies captured concepts relevant to psychosocial workplace exposures including workplace sexual harassment, psychosocial job quality, work stressors, and job control. The quality of the included studies was generally low, with six of the nine at serious risk of bias. Three studies at moderate risk of bias were included in the qualitative synthesis, and results of these showed contemporaneous exposure to sexual harassment and poor psychosocial job quality was associated with poorer mental health outcomes among young workers. Longitudinal evidence showed that exposure to low job control was associated with incident depression diagnosis among young workers. CONCLUSIONS: The findings of this review illustrate that even better studies are at moderate risk of bias. Addressing issues related to confounding, selection of participants, measurement of exposures and outcomes, and missing data will improve the quality of future research in this area and lead to a clearer understanding of how employment conditions and psychosocial workplace exposures impact the mental health of young people. Generating high-quality evidence is particularly critical given the disproportionate impact of COVID-19 on young people's employment. In preparing for a post-pandemic world where poor-quality employment conditions and exposure to psychosocial workplace exposures may become more prevalent, rigorous research must exist to inform policy to protect the mental health of young workers.

Durability and Wear Resistance of Laser-Textured Hardened Stainless Steel Surfaces with Hydrophobic Properties.

Hydrophobic surfaces are of high interest to industry. While surface functionalization has attracted significant interest, from both industry and research, the durability of engineered surfaces remains a challenge, as wear and scratches deteriorate their functional response. In this work, a cost-effective combination of surface engineering processes on stainless steel was investigated. Low-temperature plasma surface alloying was applied to increase surface hardness from 172 to 305 HV. Then, near-infrared nanosecond laser patterning was deployed to fabricate channel-like patterns that enabled superhydrophobicity. Abrasion tests were carried out to examine the durability of such engineered surfaces during daily use. In particular, the evolution of surface topographies, chemical composition, and water contact angle with increasing abrasion cycles were studied. Hydrophobicity deteriorated progressively on both hardened and raw stainless steel samples, suggesting that the major contributing factor to hydrophobicity was the surface chemical composition. At the same time, samples with increased surface hardness exhibited a slower deterioration of their topographies when compared with nontreated surfaces. A conclusion is made about the durability of laser-textured hardened stainless steel surfaces produced by applying the proposed combined surface engineering approach.

Detection of clinically relevant antimicrobial resistance determinants in warm-blooded marine animals in Livingston Island (South Shetland Islands, Antarctica): A field-based molecular genetics study.

Molecular genetic studies of stools were performed to assess the spread of some clinically relevant antimicrobial resistance determinants (ARD) in a gentoo penguin (Pygoscelis papua) and an Antarctic fur seal (Arctocephalus gazella) on Livingston Island. Glycopeptide resistance genes (vanA/vanD and vanB) were detected in both fecal samples, while the penguin's one was also mecA-positive and blaNDM-positive. Because of the remoteness and the isolation of the sampling locations, the carriage of vancomycin-resistant Enterococcus spp., methicillin-resistant Staphylococcus aureus, and NDM-producing Enterobacterales or other gram-negative bacilli suggested an ocean pollution with antibiotic resistant bacteria (ARB). Additionally, due to the type of ARD we detected, our results are alarming, and they cannot be explained only with agricultural and/or aquacultural pollution. Even though the current study is a preliminary one, it also demonstrates the potential of the field genetics analyses carried out with minimal equipment as a reliable monitoring tool for pollution with ARB.

Single-strand-specific DNase activity is an inherent property of the 140-kDa protein of the snake venom exonuclease.

Polyclonal antibodies against the exonuclease from Crotalus adamanteus venom (the 140-kDa protein) inhibit both the exonucleolytic and the single-strand-specific endonucleolytic activities, present in the exonuclease preparation. The antibodies also diminish the ability of the enzyme to split the negatively supercoiled Bluescript KS+ in the AT-rich fragment near-by the transcription termination site of the Ampicillin gene. Therefore the single-strand-specific endonucleolytic activity was attributed to the protein molecule of the exonuclease. The processivity of the exonucleolytic action was found to be less than 3 monomers as indicated by the heparin trapping method.

Kainic acid microinjected into the cat raphe dorsal nucleus modulates the somatosensory evoked potentials and their cycles of excitability.

Studies were made on the effect of the neuroexcitatory agent kainic acid, microinjected into raphe dorsal nucleus by glass micropipette and an air pressure system in doses ranging from 0.2 to 24.0 nmol (in volumes from 0.05 microliter to 0.47 microliter), on the somatosensory evoked potentials and their cycles of recovery (excitability) obtained from cortex (primary somatosensory and parietal associative), thalamus (ventral posterolateral nucleus and centre median nucleus), mesencephalic reticular formation and raphe dorsal nucleus. Kainic acid in doses higher than 3 nmol exerted an activating effect on the evoked potentials and their recovery cycles especially in thalamus and mesencephalic reticular formation. The analysis of these electrophysiological parameters revealed that the non-specific structures were involved to a larger extent in the activating effect of kainic acid than the specific ones. The morphological changes were not severe and were limited to a part of the raphe dorsal nucleus neurons. Our data indicate that kainic acid injected into raphe dorsal nucleus modulates (in direction of facilitation) the somatosensory evoked potentials and their cycles of excitability obtained in some brain structures. The results suggest that this nucleus is involved in the somatosensory information processing in a non-specific manner.

Drosophila melanogaster ferritin: cDNA encoding a light chain homologue, temporal and tissue specific expression of both subunit types.

Drosophila melanogaster secreted ferritin like the cytosolic ferritins of other organisms is composed of two subunits, a heavy chain homologue (HCH) and a light chain homologue (LCH). We report the cloning of a cDNA encoding the ferritin LCH of this insect. As predicted from the gene sequence, it contains no iron responsive element (IRE). Northern blot analysis reveals two mRNAs that differ in length due to the choice of polyadenylation signals. Message levels vary through the life cycle of the fly and are markedly increased by high levels of dietary iron. The gut is the main site of increased message synthesis and iron preferentially increases the amount of shorter messages. Western blotting reveals that LCH is the predominant ferritin subunit in all life stages. The amount of LCH protein corresponds well with the message levels in control animals, while in iron-fed animals LCH does not increase proportionally with the message levels. In contrast, the amount of HCH is less than that would be predicted from message levels in control animals, but corresponds well in iron-fed animals. Ferritin is abundant in gut and hemolymph of larvae and adults and in ovaries of adult flies. At pupariation, ferritin becomes more abundant in hemolymph than in other tissues.

The effect of thioacetamide on rat liver plasma membrane enzymes and its potentiation by fasting.

Thioacetamide, given intraperitoneally (1.4 mmol/kg body mass) to male Wistar rats 24 h before sacrifice promoted a marked elevation of serum aminotransferases, loss of microsomal cytochrome P-450 content and a significant reduction (about 50%) of the liver plasma membrane enzymatic activities (5'-nucleotidase; K+, Na+- and Mg2+-adenosine triphosphatases; and gamma-glutamyl transferase). Previous starvation for 48 h, immediately prior to thioacetamide administration, strongly potentiated the effects of thioacetamide on the serum, microsomal and liver plasma membrane parameters, while fasting itself did not affect them. The liver plasma membrane damage may be one of the reasons for the cell death in thioacetamide-intoxicated rat livers.

Rat liver plasma membrane damage in hexachlorobenzene intoxication and its potentiation by ethanol.

Chronic feeding of male Wistar rats with food containing hexachlorobenzene (HCB) at 17.5 mmol/kg induced elevation of serum amino-transferases and bilirubin content, increase of microsomal cytochrome P-450 concentration, and decrease of 5'-nucleotidase, K+,Na+- and Mg2+-adenosine triphosphatase activities in liver plasma membrane preparations. These changes were potentiated by ethanol consumption suggesting a possible role of liver plasma membrane damage in the pathogenesis of HCB intoxication.

Synthesis and antitumour activity of several new 4-aroyl-1-nitrosohydrazinecarboxamides.

Six new analogues of nitrosoureas containing aroylhydrazine residue have been synthesized: (I) 4-(2-fluorobenzoyl)-1-(2-chloroethyl)-1-nitrosohydrazinecarboxamide++ +; (II) 4-(4-bromobenzoyl)-1-(2-chloroethyl)-1-nitrosohydrazinecarboxam ide; (III) 4-(4-hydroxybenzoyl)-1-(2-chloroethyl)-1-nitrosohydrazinecarboxamide+ ++; (IV) 4-(3-methoxybenzoyl)-1-(2-chloroethyl)-1-nitrosohydrazinecarbox amide; (V) 4-(4-methoxybenzoyl)-1-(2-chloroethyl)-1-nitrosohydrazinecarbox amide; (VI) 4-(4-fluorophenylacetyl)-1-(2-chloroethyl)-1-nitrosohydrazineca rboxamide. All six compounds showed a dose-dependent in vivo activity against leukaemias L1210 and P388. Compounds I and III were soluble in water. The antitumour effects were highly expressed in compound III, yielding a T/C% value of 402% in leukaemia P388, and in compound VI, 356% in leukaemia L1210.

Changes in the EEG-reactions to repetitive peripheral and central electrical stimulation by intraraphedorsal kainic acid in the cat.

The effect of kainic acid (KA) microinjected into the dorsal raphe nucleus (NRD) of the cat through glass micropipette by means of an air pressure system in doses ranging from 2.3 to 23.5 nmol on the electroencephalographic (EEG)-reactions elicited by repetitive (6-10 Hz) peripheral (somatic and visual) or central electrical stimulation was investigated. A significant facilitation of the driving reaction evoked by rhythmic subcutaneous electrical stimulation of the forepaw was found after KA, while the driving reaction elicited by repetitive photostimulation did not change. The cortical rhythmic reactions to repetitive electrical stimulation of the specific and nonspecific nuclei of the thalamus and of the caudate nucleus (where inhibitory mechanisms are known to be involved) diminished or disappeared when generalized paroxysmal spontaneous activity occurred after kainic acid. The EEG-reaction to stimulation of the mesencephalic reticular formation was significantly facilitated after KA. The repetitive electrical stimulation of the ventral posterolateral nucleus, the centre median and the mesencephalic reticular formation also provoked the appearance of paroxysmal EEG activity or afterdischarge which in some cases developed into epileptic seizures. The data show that kainic acid injected into the dorsal raphe nucleus increases (probably by disinhibition) the excitability level of some forebrain structures connected with the nucleus.

Effect of piracetam on the electrocorticogram after traumatic brain oedema in cats.

The effect of piracetam on the electrocorticogram changes caused by experimentally-induced traumatic brain oedema in cats has been studied. The trauma was evoked by sticking a needle through the parietal associative cortical area. The electrocorticogram amplitude and frequency depression of the injured cortical area was eliminated and the bioelectrical activity restored to a normal pattern 22.4 +/- 10.3 min after a single dose of piracetam (100 mg/kg i.v.). The results indicate that piracetam recovered the cortical bioelectrical activity disturbed by experimentally-induced traumatic oedema. The beneficial effect of piracetam is probably due to an optimization of the functional state of the brain since piracetam acts as a nonspecific activator of brain excitability.

Effect of aligeron and cinnarizine in models of general and local depression of the cortical bioelectrical activity in cats.

The effect of aligeron (5 mg/kg i.v.) and cinnarizine (10 mg/kg i.v.) on general and local depression of cortical bioelectrical activity was studied in acute experiments on cats. Asphyxic anoxia and hypoventilation hypoxia were used as models of general depression. Local depressions were caused by topical application of potassium chloride (KCl) and adenosine-5'-monophosphate (AMP) on the cortex. In hypoventilation hypoxia aligeron and cinnarizine increased cortical resistance to hypoxia and accelerated the recovery of cortical bioelectrical activity. In KCl- and AMP-induced depressions the drugs showed a protective effect manifested in a decrease of the degree and duration of the depression. In asphyxic anoxia their effect was insignificant.

Piracetam and brain excitability. An electrophysiological study in cats.

The effect of piracetam on the excitability of the brain has been examined in cats by electrophysiological approaches: spontaneous electrocorticogram (ECoG), visual evoked potentials (VEPs) and their recovery cycles in some brain structures (visual and associative cortex, lateral geniculate body, centrum medianum thalami and mesencephalic reticular formation). Piracetam (100 mg/kg i.v.) increased the spectral power of ECoG and particularly in the associative cortex for the frequency bands of 10-12 and 19-22 Hz. Piracetam decreased the early components and facilitated the late components of VEPs predominantly in the associative cortex. Changes were found in the recovery cycles too, namely, facilitation and shortening of recovery in all structures studied except in lateral geniculate body. The data suggest that piracetam acts as a non-specific activator on the excitability thus optimizing the functional state of the brain.

Epileptogenic effect of intracortically applied kainic acid in cats.

The effect of two doses (5 micrograms/microliters) of kainic acid (KA) injected intracortically into the posterior lateral gyrus of cats was investigated. KA in a dose of 5 micrograms/microliters provoked cortical epileptogenic focus 8-12 min after its application, developing later into a focal seizure. Administration of 10 micrograms/microliters KA resulted after 15-20 sec in paroxysmal discharges of spikes and sharp-slow waves at the site of the application, which propagated ipsilaterally. Thereafter the paroxysmal activity spread contralaterally, became generalized and developed into an epileptic state. The effect of KA was considered to be a dose-dependent one. N-Aminomethylpiperazine-3, 3-diethyl-2, 4-pyridinedione (DKMP) in a dose of 100 mg/kg injected i.v. on the background of developed epileptic state exerted a rapid inhibitory effect of 60-100 min duration on the paroxysmal activity. employed as a model of secondary generalized focal epilepsy.

Generalized epilepsy induced by kainic acid and anticonvulsant effect of N-aminomethylpiperazine-3,3-diethyl-2,4-pyridinedione.

Systemic administration of kainic acid in rats (30 mg/kg s.c.) and cats (5 mg/kg i.p.) produced after a definite period (30 to 60 min) secondary generalized seizures occurring first in the limbic structures (amygdala and hippocampus). The effect of N-aminomethylpiperazine-3,3-diethyl-2,4-pyridinedione (DKMP) at a dose of 100 mg/kg i.v. was evaluated on the background of developed kainic epilepsy. In rats, DKMP inhibited kainic clonic and tonic seizures and 100% of the animals survived. The drug was ineffective against limbic seizures. In cats, DKMP strongly suppressed the cortical EEG paroxysmal activity and slightly influenced the limbic one. The present data contribute to the knowledge of the anticonvulsive activity of DKMP, showing it to be a promising antiepileptic drug with mainly cortical action.

Electrophysiological effects of propranolol and carbachol locally injected into nucleus raphe dorsalis in cats.

The effect of propranolol and carbachol injected directly into nucleus raphe dorsalis (RD) on the evoked potentials, their recovery cycles and on the spontaneous EEG activity recorded in the RD and the visual and somatosensory cortical regions was investigated. It was found that the changes in these electrophysiological parameters induced by propranolol and carbachol were similar and showed an increase in the excitability level in both the RD and the neocortex, mainly in the somatosensory cortex. The activating effect of carbachol was much more pronounced as compared with that of propranolol. The results are discussed in relation to the possible interactions between various neurotransmitter systems within the RD as well as to the data about the presumed role of this nucleus in some behavioral and/or electrophysiological manifestations. The findings suggest that raphe dorsalis participates in the regulation of the cortical excitability and apparently represents a system which modulates the transMission and integration of sensory information.

Incidence of spinal cord injuries in Plovdiv and Plovdiv region, Bulgaria.

This retrospective study was conducted to evaluate the incidence of spinal cord injuries in Plovdiv and Plovdiv region, Bulgaria. The study material comprised 980 patients treated over a period of 10 years (1983-1992) in the Clinics of Traumatic and Orthopaedic Surgery and Neurosurgery, University of Medicine, Plovdiv, which are the only therapeutic establishment in this region with a population of 750,000 to admit and treat this type of injury. Conservative treatment was applied in 34.46% of the patients using various methods: the method of Gorinevska-Dreving, immobilisation in either a plaster jacket or minerva depending on the injury site, the reclination methods of Davis-Erie or Watson-Jones, cranial extension by Crutchfield. Operative treatment also was used and included posterior stabilisation with or without bone plastics, anterior vertebrodesis in the cervical and thoracolumbar regions from a transpleural and retroperitoneal approaches and anterior vertebrodesis with a partial or complete replacement of the vertebral body.

[Antibodies to Brucella in caspian seals]. / Antitela k brutsellam u kaspiiskikh tiulenei.

As the result of the study of Caspian seals, the presence of antibodies to Brucella was detected in the blood serum of these animals. The annual dynamics of the proportion of seropositive animals was noted. These data indicate the possibility of the circulation of the infective agent of brucellosis in the population of Caspian seals.

Encapsulation of Au Nanoparticles on a Silicon Wafer During Thermal Oxidation.

We report the behavior of Au nanoparticles anchored onto a Si(111) substrate and the evolution of the combined structure with annealing and oxidation. Au nanoparticles, formed by annealing a Au film, appear to "float" upon a growing layer of SiO2 during oxidation at high temperature, yet they also tend to become partially encapsulated by the growing silica layers. It is proposed that this occurs largely because of the differential growth rates of the silica layer on the silicon substrate between the particles and below the particles due to limited access of oxygen to the latter. This in turn is due to a combination of blockage of oxygen adsorption by the Au and limited oxygen diffusion under the gold. We think that such behavior is likely to be seen for other metal-semiconductor systems.

A newly discovered bacteriocin produced by Enterococcus faecalis 3915.

Different Enterococci, isolated from starters for the production of the traditional Bulgarian yellow cheese 'Kashkaval' were screened for bacteriocin production, and one of them, Enterococcus faecalis 3915 demonstrated bacteriocin activity. In this study, we investigated the growth parameters of the producer strain as well as the production kinetics and preliminary characterisation of the produced bacteriocin named enterocin 3915. For the growth modelling, the logistic model was used, while bacteriocin production was monitored. Experiments on inducibility were conducted, and strain was checked for the presence of plasmids. The peptide was crudely purified by ammonium sulphate precipitation followed by preparative PAGE. The approximate molecular mass was determined electrophoretically, and the activity was visualised by electrophoresis and agar overlay technique. It was found that E. faecalis 3915 produces a bacteriocin with constitutive synthesis and chromosomal localisation of its genetic determinants. The peptide revealed to be relatively heat-stable with a molecular mass of about 6.5 kDa. As E. faecalis 3915 originates from cheese starter it can be classified as generally recognised as safe (GRAS). The inhibitory activity of enterocin 3915 comprises commensals or pathogens, so properties generally accepted as probiotic could be attributed to the producer, and potential application in the dairy industry is not to be excluded.