Novi aspekti u klasifikaciji kancerogena

The existing systems of classification of carcinogens should include a distinction between genotoxic and non-genotoxic chemicals. For non-genotoxic chemicals, permissible exposure levels can be derived at which no relevant human cancer risks are anticipated. While genotoxic carcinogens can induce chromosomal effects without mutagenic action, non-DNA-reactive genotoxins affecting topoisomerase or the spindle, or those having an exclusively aneugenic effect can be carcinogenic only at high, toxic doses. Specific mechanisms of clastogenicity and processes of carcinogenesis based on reactive oxygen have practical thresholds. Since reactive oxygen species (ROS) are generally genotoxic, the question is whether chemicals that increase ROS production will add to endogenously produced background levels and lead to nonlinear dose-effect relationships. Taking into account the presence of endogenous carcinogens, it is now becoming evident that carcinogenic risk extrapolation to low doses must be considered according to the mode of action.U postojećem sistemu klasifikacije kancerogenih tvari utvrđena je razlika između genotoksičnih i negenotoksičnih kemikalija. Za negenotoksične kemikallije mogu se izvesti pretpostavljeni stupnjevi izlaganja kod kojih ne postoji značajan rizik od pojave raka kod ljudi. Za genotoksične kancerogene mogući su na primjer inducirani kromosomski efekti bez početka procesa mutageneze, dok genotoksični toksini koji se ne vežu za DNA-molekulu, a djeluju na topoizomere ili diobeno vreteno ili su aneugeni, izazivaju kancerogene efekte jedino u visokim, toksičnim dozama. Za specifične mehanizme klastrogenog djelovanja i procesa kancerogeneze koji se baziraju na reaktivnom kisiku postoji prag početka procesa. Kako su vrste kemikalija reaktivne na kisik (ROS) u načelu genotoksične, pojavljuju se pitanja da li kemikalije koje povećavaju produkciju ROS-vrsta treba pridodati endogenim kancerogenima pozadinskog stupnja koji uzrokuju nelinearni odnos doze i učinka. Uzimajući u obzir rasprave o prisutnosti endogenih kancerogena, sada postaje jasno da se kancerogeni rizik od niskih doza mora uzeti u obzir sukladno načinu njihova djelovanja

Громадянське виховання підлітків у контексті педагогічної спадщини А. Б. Рєзніка

У статті висвітлено основні положення педагогічної спадщини видатного педагога Кіровоградщини А. Б. Рєзніка в царині громадянського виховання. Доведено, що теоретичні положення, педагогічні висновки, методичні поради, які він розробив, набувають особливої актуальності у наш час і їх застосування у виховній практиці, сприятиме вибору активної життєвої позиції та свідомому формуванню громадянського світогляду молоді

Response of rat alveolar type II cells and human lung tumor cells towards oxidative stress induced by hydrogen peroxide and paraquat,”Toxicology

Abstract The expression of MDR1b coding mRNA is increased in alveolar type II cells from juvenile rat lung in culture. Hydrogen peroxide and paraquat-induced further upregulation supporting that oxidative stress mediated mechanisms are involved in the regulation of MDR1b in rat lung. The expression rates of mRNA for catalase, Cu/Zn-superoxide dismutase (Cu/Zn-SOD) and Mn-superoxide dismutase (Mn-SOD) remains constant during culture and were not modulated by hydrogen peroxide or paraquat. Thus, antioxidative enzymes in primary A II cells from rat lung are not regulated by reactive oxygen species dependent mechanisms. Primary A II cells were substantially more sensitive towards paraquat-induced cytotoxicity and lipid peroxidation than the permanent human lung tumor cell lines H322 and H358. A 100 M hydrogen peroxide for 2 h induces substantial DNA damage which is not paralleled by an increased rate of lipid peroxidation. The expression rate of mRNA coding for catalase and Mn-SOD was not changed and almost the same is true for the activity of catalase and Cu/Zn-SOD. Only 50 M paraquat induced a significant decrease in catalase activity and an increase in Cu/Zn-SOD activity

The role of the queen mandibular gland pheromone in honeybees (Apis mellifera) : honest signal or suppressive agent?

Queen pheromones interfere with worker reproduction in social insects. However, there is still an unresolved question as to whether this pheromone acts as an “honest” signal for workers, giving a reliable indication of the queen’s reproductive value, or as a suppressive agent, inhibiting worker reproduction independent of the queen’s reproductive capacity. In honeybees (Apis mellifera), the queen’s mandibular gland secretion, a mix of fatty acids and some aromatic compounds, is crucial for regulating the reproductive division of labor in the colony inhibiting ovary development in workers. We quantified the mandibular gland secretions of virgin, drone-laying, and naturally mated queens using gas chromatography to test whether the queens’ mating, ovary activation, or the reproductive value for workers correlated with the composition of the secretion. Although the absolute amounts of the “queen substance” 9-oxo-2(E)-decenoic acid (9-ODA) were similar among the three groups, the proportions of 9-ODA decreased with increasing reproductive quality. Furthermore, the ratios of queen to worker compounds were similar in all three treatment groups, irrespective of the reproductive capacity. A multivariate analysis including all six compounds could not separate drone-laying queens from naturally mated ones, both with active ovaries but only the latter ensuring colony survival. We suggest that the mandibular gland pheromones are unlikely to function as reliable indicators of queen reproductive value and rather operate as an agent to suppress worker reproduction. This does not exclude the possibility that other “honest” pheromone signals exist in the honeybee colony, but these would have to arise from other semiochemicals, which could be produced by both the queen and the brood

Umweltgutachten 2016. Impulse für eine integrative Umweltpolitik

Ob Flächenverbrauch, Biodiversitätsverlust oder Klimawandel – klassische sektorale Umweltpolitik gerät bei den aktuellen Herausforderungen an ihre Grenzen. Der ökologische Handlungsdruck ist so groß, dass er mit einem rein technischen Umweltschutz allein nicht mehr bewältigt werden kann. Notwendig sind umfassende Veränderungen in Bereichen wie Landwirtschaft, Energie und Wohnen. Ambitionierte Umweltpolitik kann jedoch auch sozial- und wirtschaftspolitische Zielkonflikte mit sich bringen. Im vorliegenden Umweltgutachten zeigt der Sachverständigenrat für Umweltfragen (SRU), dass mithilfe von vermittelnden, integrativen Gestaltungsansätzen solche Zielkonflikte deutlich entschärft werden können. Das Umweltgutachten konzentriert sich dabei auf folgende Themen: "Vorreiterpolitik für eine ökologische Transformation", Anspruchsvoller Klimaschutz und industrielle Wettbewerbsfähigkeit“, „Umwelt- und Sozialpolitik im Kontext der Energiewende“, „Flächenverbrauch und demografischer Wandel“, „Mehr Raum für Wildnis in Deutschland“ sowie „Besserer Schutz der Biodiversität vor Pestiziden“. Der SRU berät die Bundesregierung seit 1972 in Fragen der Umweltpolitik. Die Zusammensetzung des Rates aus sieben Professorinnen und Professoren verschiedener Fachdisziplinen gewährleistet eine wissenschaftlich unabhängige und umfassende Begutachtung sowohl aus naturwissenschaftlich-technischer als auch aus ökonomischer, rechtlicher und politikwissenschaftlicher Perspektive