α-RuCl3 is a major candidate for the realization of the Kitaev quantum spin liquid, but its zigzag antiferromagnetic order at low temperatures indicates deviations from the Kitaev model. We have quantified the spin Hamiltonian of α-RuCl3 by a resonant inelastic x-ray scattering study at the Ru L3 absorption edge. In the paramagnetic state, the quasi-elastic intensity of magnetic excitations has a broad maximum around the zone center without any local maxima at the zigzag magnetic Bragg wavevectors. This finding implies that the zigzag order is fragile and readily destabilized by competing ferromagnetic correlations. The classical ground state of the experimentally determined Hamiltonian is actually ferromagnetic. The zigzag state is stabilized by quantum fluctuations, leaving ferromagnetism - along with the Kitaev spin liquid - as energetically proximate metastable states. The three closely competing states and their collective excitations hold the key to the theoretical understanding of the unusual properties of α-RuCl3 in magnetic fields.
- Publikační typ
- časopisecké články MeSH
BACKGROUND: Work-related skin diseases (WSD) are caused or worsened by a professional activity. Occupational skin diseases (OSD) need to fulfil additional legal criteria which differ from country to country. OSD range amongst the five most frequently notified occupational diseases (musculoskeletal diseases, neurologic diseases, lung diseases, diseases of the sensory organs, skin diseases) in Europe. OBJECTIVE: To retrieve information and compare the current state of national frameworks and pathways to manage patients with occupational skin disease with regard to prevention, diagnosis, treatment and rehabilitation in different European countries. METHODS: A questionnaire-based survey of the current situation regarding OSD patient management pathways was carried out with experts on occupational dermatology and/or occupational medicine from 28 European countries contributing to the European Cooperation in Science and Technology (COST) Action TD 1206 (StanDerm) (www.standerm.eu). RESULTS: Besides a national health service or a statutory health insurance, most European member states implemented a second insurance scheme specifically geared at occupational diseases [insurance against occupational risks (synonyms: insurance against work accidents and occupational injuries; statutory social accident insurance)]. Legal standards for the assessment of occupationally triggered diseases with a genetic background differ between different countries, however, in most European member states recognition as OSD is possible. In one-third of the countries UV light-induced tumours can be recognized as OSD under specific conditions. CONCLUSION: OSD definitions vary between European countries and are not directly comparable, which hampers comparisons between statistics collected in different countries. Awareness of this fact and further efforts for standardization are necessary.
- MeSH
- kožní nemoci epidemiologie terapie MeSH
- lidé MeSH
- nemoci z povolání epidemiologie terapie MeSH
- průzkumy a dotazníky MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Evropa epidemiologie MeSH
The nutritional status of a selected population--859 male members of the Fire Rescue Service from 12 districts in the Czech Republic--was assessed in 1997 and 1998. The study provides extensive information on selected anthropometrical and biochemical parameters, especially on those, which are generally used as risk indices for the origin and development of cardiovascular disease (CVD): body mass index (BMI), body fat percentage (b. fat), waist circumference (waist), serum concentrations of total cholesterol (Tchol), HDL- and LDL-cholesterol (HDL-chol, LDL-chol), triacylglyceroles (TAG) and the atherogenic index (AI). As far as lipid parameters were concerned, increased serum levels were estimated in 30.4% (TAG), 54% (Tchol) and 60.9% (LDL-chol) of volunteers. Decreased serum levels of HDL-chol were found in 38.2% of volunteers. An AI higher than 3.5 a.u. was calculated for 79.9% of all subjects in study while an AI higher than 5.0 a.u. was calculated for 45.3% of all subjects. An AI higher than 3.5 a.u. was found in 62% of males with normal weight, in 85% of overweight males and in 92% of obese males. The results of the study proved the considerable prevalence of the overweightness and obesity in the male population group that was followed: according to the calculated BMI, 49.5% of volunteers were estimated to be overweight and 16.3% to be obese. The study concept made it possible to reveal the relationships among the anthropometrical and biochemical parameters followed. The correlation matrix documents a statistically significant dependence among the BMI or waist values and the serum concentrations of Tchol, LDL-chol, TAG and AI. A significant negative correlation was found between the HDL-chol serum concentration and the BMI or waist values. The variance analysis results (the estimated lipid parameter values were divided into groups according to BMI and waist categories) document a statistically significant increase in serum Tchol, LDL-chol, TAG and AI in age categories over 35 years in comparison with the category of men under 25 years of age. For Tchol and LDL-chol a statistically significant increase had already been found in the 25-35 year age category. In comparison with the normal weight category, Tchol serum levels and AI values were statistically significantly higher in both the overweight and obese categories. Statistically significant increase was proven for the TAG and LDL-chol serum levels in both the overweight II. gr. and obese categories. A statistically significant decrease in comparison with the normal weight category was found in the HDL-chol serum levels of both the overweight and obesity categories. In the same way, an increase in Tchol and LDL-chol, TAG serum concentrations and AI values in higher and high risk CVD categories (according to the waist circumference value) was found in comparison with the low CVD risk category.
- MeSH
- antropometrie MeSH
- dospělí MeSH
- index tělesné hmotnosti MeSH
- kardiovaskulární nemoci etiologie MeSH
- lidé středního věku MeSH
- lidé MeSH
- lipidy krev MeSH
- obezita krev komplikace MeSH
- rizikové faktory MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
- Názvy látek
- lipidy MeSH
A rise of the intracellular serine proteinase activity (ISP) during postexponential growth of Bacillus subtilis was decreased by a temperature upshift from 35 degrees to 42 degrees C. However, the amount of both molecular forms of the major intracellular serine proteinase ISP1 determined by immunoblotting was similar at both temperatures or even slightly increased at 42 degrees C. The evolution of the ISP activity in B. megaterium showed an opposite temperature dependence, being faster during growth at 42 degrees C. The amount of immunologically detected ISP1 again did not correlate well with the enzyme activity. Moreover, most of the ISP1 molecules in cell-free extracts from B. megaterium were inactive and were activated by increasing the CaCl2 concentration up to 30 mM--unlike B. subtilis, where the enzymic activity was unaffected by Ca2+ concentration. These data suggest that the ISP1 activity in the two bacillar species during postexponential growth is regulated posttranscriptionally, but that the regulatory mechanisms differ.
- MeSH
- aktivace enzymů MeSH
- Bacillus megaterium enzymologie fyziologie MeSH
- Bacillus subtilis enzymologie fyziologie MeSH
- cytoplazma enzymologie MeSH
- elektroforéza v polyakrylamidovém gelu MeSH
- kultivační média MeSH
- osmotický tlak MeSH
- proteiny teplotního šoku metabolismus MeSH
- protilátky bakteriální imunologie MeSH
- serinové endopeptidasy biosyntéza imunologie metabolismus MeSH
- spory bakteriální MeSH
- teplota MeSH
- vápník metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- kultivační média MeSH
- proteiny teplotního šoku MeSH
- protilátky bakteriální MeSH
- serinové endopeptidasy MeSH
- vápník MeSH
The authors present the results of an epidemiological study focused on monitoring selected anthropometric parameters which characterize the nutrition state. 933 volunteers altogether, in age group 19-60 years, were tested in the study. Anthropometric parameters such as weight, height, skinfold thickness and abdomen circumference were measured. BMI and fat tissue percentage were calculated on the basis of gathered data. Overweight was detected in 67.5% of monitored men, obesity in 17.0% of them. Overweight was detected in 50.0% of women, obesity in 18.9% of them. Waist circumference exceeding 102 cm was measured in 41.2% of men and waist circumference exceeding 88 cm in 41.7% of monitored women. The unfavourable nutrition state correlates with a high occurrence of cardiovascular and metabolic diseases appearing within the Czech population.
- MeSH
- antropometrie MeSH
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- obezita epidemiologie MeSH
- prevalence MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
- Geografické názvy
- Česká republika epidemiologie MeSH
Elevated concentration of NaCl in liquid medium caused a concentration-dependent growth delay (adaptation lag) and decrease in the maximal growth rate of Bacillus megaterium. The adaptation to salt stress was accompanied by transformation of some otherwise stable (long-lived; LLP) cell proteins into quickly degraded (short-lived; SLP) ones. Exposure to the strongly growth-reducing 1 M NaCl increased the size of the SLP 'pool' of intracellular proteins from about 5 to about 15% of total protein. The major intracellular proteolytic capacity of B. megaterium is represented by intracellular serine proteinases (ISP). Paradoxically, their specific activity was lowered or masked during the adaptation phase marked by increased catabolism of short-lived and/or destabilized proteins by the stress. This documents that intracellular proteolytic activity cannot be a key regulator of protein catabolism during adaptation to stress.
- MeSH
- Bacillus megaterium růst a vývoj metabolismus ultrastruktura MeSH
- bakteriální proteiny metabolismus MeSH
- chlorid sodný farmakologie MeSH
- elektronová mikroskopie MeSH
- fyziologická adaptace * MeSH
- kinetika MeSH
- kultivační média MeSH
- osmotický tlak MeSH
- serinové endopeptidasy metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- bakteriální proteiny MeSH
- chlorid sodný MeSH
- kultivační média MeSH
- serinové endopeptidasy MeSH
In Bacillus megaterium, a temperature that suppresses sporulation (43 degrees C) only slightly exceeds both the optimum growth temperature and the temperature still permitting sporulation (40-41 degrees C). Here we show that, when cells grown at 35 degrees C and transferred to a sporulation medium, were subjected to shifts between 35 degrees C and the sporulation suppressing temperature (SST, 43 degrees C), their development and proteolytic activities were deeply affected. During the reversible sporulation phase that took place at 35 degrees C for 2-3 h (T2-T3), the cells developed forespores and their protein turnover was characterized by degradation of short-lived proteins and proteins made accessible to the proteolytic attack because of starvation. During the following irreversible sporulation phase refractile heat-resistant spores appeared at T4-T5. Protein turnover rate increased again after T2 and up to T8 60-70% prelabelled proteins were degraded. The SST suppressed sporulation at its beginning; at T3 no asymmetric septa were observed and the amount of heat-resistant spores at T8 was by 4-5 orders lower than at 35 degrees C. However, the cells remained viable and were able to sporulate when transferred to a lower temperature. Protein degradation was increased up to T3 but then its velocity sharply dropped and the amount of degraded protein at T8 corresponded to slightly more than one-half of that found at 35 degrees C. The cytoplasmic proteolytic activity was enhanced but the activity in the membrane fraction was decreased. When a temperature shift to SST was applied at the beginning of the irreversible sporulation phase (T2.5), the sporulation process was impaired. A portion of forespores lyzed, the others were able to complete their development but most spores were not heat-resistant and their coats showed defects. Protein degradation increased again because an effective proteolytic system was developed during the reversible sporulation phase but the amount of degraded protein was slightly lower than at 35 degrees C. A later (T4) shift to SST had no effect on the sporulation process.
- MeSH
- Bacillus megaterium metabolismus ultrastruktura MeSH
- bakteriální proteiny metabolismus MeSH
- endopeptidasy metabolismus MeSH
- kinetika MeSH
- spory bakteriální metabolismus ultrastruktura MeSH
- teplota MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- bakteriální proteiny MeSH
- endopeptidasy MeSH
Oxidative stress in microbial cells shares many similarities with other cell types but it has its specific features which may differ in prokaryotic and eukaryotic cells. We survey here the properties and actions of primary sources of oxidative stress, the role of transition metals in oxidative stress and cell protective machinery of microbial cells, and compare them with analogous features of other cell types. Other features to be compared are the action of Reactive Oxygen Species (ROS) on cell constituents, secondary lipid- or protein-based radicals and other stress products. Repair of oxidative injury by microorganisms and proteolytic removal of irreparable cell constituents are briefly described. Oxidative damage of aerobically growing microbial cells by endogenously formed ROS mostly does not induce changes similar to the aging of multiplying mammalian cells. Rapid growth of bacteria and yeast prevents accumulation of impaired macromolecules which are repaired, diluted or eliminated. During growth some simple fungi, such as yeast or Podospora spp., exhibit aging whose primary cause seems to be fragmentation of the nucleolus or impairment of mitochondrial DNA integrity. Yeast cell aging seems to be accelerated by endogenous oxidative stress. Unlike most growing microbial cells, stationary-phase cells gradually lose their viability because of a continuous oxidative stress, in spite of an increased synthesis of antioxidant enzymes. Unlike in most microorganisms, in plant and animal cells a severe oxidative stress induces a specific programmed death pathway--apoptosis. The scant data on the microbial death mechanisms induced by oxidative stress indicate that in bacteria cell death can result from activation of autolytic enzymes (similarly to the programmed mother-cell death at the end of bacillary sporulation). Yeast and other simple eukaryotes contain components of a proapoptotic pathway which are silent under normal conditions but can be activated by oxidative stress or by manifestation of mammalian death genes, such as bak or bax. Other aspects, such as regulation of oxidative-stress response, role of defense enzymes and their control, acquisition of stress tolerance, stress signaling and its role in stress response, as well as cross-talk between different stress factors, will be the subject of a subsequent review.
- MeSH
- antioxidancia metabolismus MeSH
- Bacteria cytologie metabolismus MeSH
- biologické modely MeSH
- buněčná smrt MeSH
- houby cytologie metabolismus MeSH
- kovy metabolismus MeSH
- metabolismus lipidů MeSH
- mikrobiologie * MeSH
- oxidační stres * MeSH
- poškození DNA MeSH
- reaktivní formy kyslíku metabolismus MeSH
- rostliny metabolismus MeSH
- stárnutí buněk MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
- srovnávací studie MeSH
- Názvy látek
- antioxidancia MeSH
- kovy MeSH
- reaktivní formy kyslíku MeSH
In Bacillus megaterium sporulating at 35 degreesC, up to 90% of 10-min pulse-labeled proteins were degraded. Degradation proceeded in two waves. Short-lived proteins, i.e., intrinsically labile proteins and proteins made short-lived because of starvation, were mostly degraded during the reversible sporulation phase. Their amount corresponded to 20% or slightly more during 2 h. The second wave of protein degradation, which followed during the irreversible sporulation phase at 35 degreesC, increased the amount of total degradable pulse-labeled proteins to about 90%. This wave was absent in the isogenic asporogenic mutant 27-36 or in the wild strain, whose sporulation was inhibited by increased temperature. The proportion of degradable proteins was thus reduced to less than 40% in the asporogenic mutant incubated at 35 degreesC and to 46% in the wild strain whose sporulation was suppressed by the temperature of 47 degreesC. Unlike sporulating cells, these cells were thus capable of degrading short-lived and denatured proteins, but were not able to degrade most of other proteins. The in vitro protein degradation was substantially enhanced by increasing the Ca2+ concentration, suggesting a role of Ca2+-dependent proteinase(s) in the process.
- Publikační typ
- časopisecké články MeSH
The sporicidal effect of Presept was compared with Chloramine B on the spores of Bacillus cereus. Either compound was calibrated to the same concentration of active chlorine. While a portion of spore population after 4 hrs of treatment by Chloramine germinated and started to divide in a rich nutrient medium, the optical density of the culture inoculated with spores treated by Presept did not increase even after 7 hrs when exposed to the nutrient medium. Significant morphological differences were found in either population of spores. Spores treated by Presept lost the impermeability within 3 hrs in the nutrient medium but almost no postgerminative development was observed. However, a portion of spores treated by Chloramine B developed after germination within 3 hrs into vegetative cells. It seems that Presept does not block germination and/or loss of impermeability of spores, but prevents their postgerminative development and division.
- MeSH
- Bacillus cereus účinky léků MeSH
- chloraminy farmakologie MeSH
- dezinficiencia farmakologie MeSH
- lidé MeSH
- spory bakteriální účinky léků MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
- Názvy látek
- chloramine-B MeSH Prohlížeč
- chloraminy MeSH
- dezinficiencia MeSH
