Oxidative stress-induced DNA damage by particulate air pollution

Exposure to ambient air particulate matter (PM) is associated with pulmonary and cardiovascular diseases and cancer. The mechanisms of PM-induced health effects are believed to involve inflammation and oxidative stress. The oxidative stress mediated by PM may arise from direct generation of reactive oxygen species from the surface of particles, soluble compounds such as transition metals or organic compounds, altered function of mitochondria or NADPH-oxidase, and activation of inflammatory cells capable of generating ROS and reactive nitrogen species. Resulting oxidative DNA damage may be implicated in cancer risk and may serve as marker for oxidative stress relevant for other ailments caused by particulate air pollution. There is overwhelming evidence from animal experimental models, cell culture experiments, and cell free systems that exposure to diesel exhaust and diesel exhaust particles causes oxidative DNA damage. Similarly, various preparations of ambient air PM induce oxidative DNA damage in in vitro systems, whereas in vivo studies are scarce. Studies with various model/surrogate particle preparations, such as carbon black, suggest that the surface area is the most important determinant of effect for ultrafine particles (diameter less than 100 nm), whereas chemical composition may be more important for larger particles. The knowledge concerning mechanisms of action of PM has prompted the use of markers of oxidative stress and DNA damage for human biomonitoring in relation to ambient air. By means of personal monitoring and biomarkers a few studies have attempted to characterize individual exposure, explore mechanisms and identify significant sources to size fractions of ambient air PM with respect to relevant biological effects. In these studies guanine oxidation in DNA has been correlated with exposure to PM(2.5) and ultrafine particles outdoor and indoor. Oxidative stress-induced DNA damage appears to an important mechanism of action of urban particulate air pollution. Related biomarkers and personal monitoring may be useful tools for risk characterization.     

Effects of air ions on some aspects of learning and memory of rats and mice

When submitted to a single avoidance task male mice showed different behavioral responses if previously treated with opposite aeroionization polarities. Whereas negative air ions tend to improve learning, positive ions have disturbing effects. Male rats submitted to a single — trial inhibitory avoidance step-through task showed that retention processes may also be influenced by air ions. The positive air-ion-treated animals exhibit signs of impaired short and long term memory. The slightly impaired score of negative air-ion-treated animals seems only dependent upon the simultaneously increased locomotor activity. A separate experiment supported this hypothesis showing conspicuous differential effects of air ion polarity on spontaneous activity of male rats. On the basis of these findings and the results of other studies in biological air ion dependence field, the behavioral significance of aero-ionization in learning and memory processes is discussed in relation to serotonin metabolism and other neuroendocrine mechanisms.     

High air humidity is sufficient for successful egg incubation and early post‐embryonic development in the marbled crayfish (Procambarus virginalis)

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Sensitivity of Candida albicans to negative air ion streams

Negative air ions (NAIs) are known to kill C. albicans; however, their precise mechanism of action is uncertain. Elucidation of this has been hampered by a lack of reproducibility between results obtained by different investigators. The aim of this study was to determine the influence of variation in experimental parameters on the sensitivity of C. albicans to negative air ions and the role of ozone in this process. Ten strains of C. albicans were exposed to NAIs generated at different emitter distances, exposure times, relative humidities and under aerobic and oxygen-free conditions. In further experiments, ozone levels were measured under the same conditions. The effect of NAIs on C. albicans growth was assessed by measuring the area of the zone of inhibition generated around the electrode of the ionizer. There was a significant reduction in area of zone of inhibition with increasing emitter distance (P < 0.05), relative humidity (P < 0.05) or under oxygen-free conditions (P < 0.05). Increases in exposure time resulted in a significant increase in growth inhibition (P < 0.05). Ozone levels increased with increasing exposure times (P < 0.01) but were significantly reduced as emitter distance increased (P < 0.01). When utilized in a nonventilated room, levels of ozone produced did not exceed recognized safety limits. These results (a) demonstrate the importance of careful control of experimental parameters if reproducibility of studies involving NAIs is to be achieved, and (b) highlight the possible role of ozone in the microbicidal effects of NAIs.     

Desaturation of exhaled air in camels

We have found that camels can reduce the water loss due to evaporation from the respiratory tract in two ways: (1) by decreasing the temperature of the exhaled air and (2) by removal of water vapour from this air, resulting in the exhalation of air at less than 100% relative humidity (r.h.). Camels were kept under desert conditions and deprived of drinking water. In the daytime the exhaled air was at or near body core temperature, while in the cooler night exhaled air wat at or near ambient air temperature. In the daytime the exhaled air was fully saturated, but at night its humidity might fall to approximately 75% r.h. The combination of cooling and desaturation can provide a saving of water of 60% relative to exhalation of saturated air at body temperature. The mechanism responsible for cooling of the exhaled air is a simple heat exchange between the respiratory air and the surfaces of the nasal passageways. On inhalation these surfaces are cooled by the air passing over them, and on exhalation heat from the exhaled air is given off to these cooler surfaces. The mechanism responsible for desaturation of the air appears to depend on the hygroscopic properties of the nasal surfaces when the camel is dehydrated. The surfaces give off water vapour during inhalation and take up water from the respiratory air during exhalation. We have used a simple mechanical model to demonstrate the effectiveness of this mechanism.     

On the mechanism of air ventilaton in anabantoids (Pisces: Teleostei)

Summary Air ventilation in most Anabantoid species is diphasic, consisting of exhalation and inhalation. Exhalation is the release of air from the accessory breathing organs (suprabranchial chambers) through the mouth either into the water near the surface (e.g.,Ctenopoma) or directly into the atmosphere (e.g.,Osphronemus goramy). Inhalation, i.e., taking in fresh air through the mouth at the surface, immediately follows exhalation. X-ray films show (Figs. 5 and 6) that evacuation of the suprabranchial chambers during exhalation is total or nearly total. This, together with the fact that these chambers can contract at most to a very small extent, led to the conclusion that gas is replaced by water entering the chambers during exhalation and that this water is replaced by fresh air during inhalation. Further analysis of films, including conventional films showing the behavior of the opercular apparatus during air ventilation (Fig. 7), leads to a theory of a double-pumping mechanism responsible for air ventilation. This mechanism consists of the buccal apparatus and the opercular apparatus. It is suggested that both of these structures are able to act as both suction and pressure pumps, and thus air ventilation may be explained as the result of alternating activity of these two pumps.In the monophasic air ventilation characteristic of (adult)Anabas testudineus, there is no exhalation phase comparable to that of other Anabantoids. Therefore, no water enters the suprabranchial chambers, which remain filled with gas during the whole ventilation process (Fig. 10). Ventilation is limited to one phase comparable to inhalation in other Anabantoids.The structure of the accessory breathing organs (Fig. 1) and its progressive complication with growth (Fig. 4) were studied inOsphronemus goramy. The arrangement of the labyrinthine plates is in accordance with the requirements of transport of water and gas through the suprabranchial chambers. One plate (the inner plate, Fig. 1) separates these chambers into atrium, ventro-caudal, and dorso-caudal compartments, each with its own opening (valve). This organization seems essential for the transport of gas and water through the suprabranchial chambers and ensures that during exhalation, water flows into the chambers from above, so that while water is filling these chambers displaced gas can be sucked through the deep-lying pharyngeal openings into the expanding buccal cavity.Supported by the Deutsche Forschungsgemeinschaft     

Stomatal responses to humidity in air and helox

Abstract. Stomatal responses to humidity were studied in several species using normal air and a helium: oxygen mixture (79:21 v/v, with CO₂ and water vapour added), which we termed 'helox'. Since water vapour diffuses 2.33 times faster in helox than in air, it was possible to vary the water-vapour concentration difference between the leaf and the air at the leaf surface independently of the transpiration rate and vice versa. The CO₂ concentration at the evaporating surfaces ( c_i ), leaf temperature and photon flux density were kept constant throughout the experiments. The results of these experiments were consistent with a mechanism for Stomatal responses to humidity that is based on the rate of water loss from the leaf. Stomata apparently did not directly sense and respond to either the water vapour concentration at the leaf surface or the difference in water vapour concentration between the leaf interior and the leaf surface. In addition, stomatal responses that caused reductions in transpiration rate at low humidities were accompanied by decreases in photosynthesis at constant c_i , suggesting heterogeneous (patchy) stomatal closure.     

Effect of humidity on cuticular water permeability of isolated cuticular membranes and leaf disks

The effects of humidity on water permeability of astomatous, isolated cuticular membranes and leaf disks of Citrus aurantium L., Vinca major L., Prunus laurocerasus L., Hedera helix L. and Forsythia intermedia (Thunb.) Vahl. were investigated by a new method using 3H2O. With isolated cuticular membranes of P. laurocerasus the isotope method resulted in values similar to those obtained by a well-established gravimetric method. Cuticular water permeability significantly increased by factors of 2 to 3 when air humidities increased from 2 to 100%. Plots of permeances vs. air humidity were non-linear and the slope increased with increasing air humidity. Permeances of intact leaf disks showed a response to increasing humidity similar to those of isolated cuticular membranes. When cuticular water permeability was measured using wax-free, isolated polymer matrix membranes that had been methylated, the effect of air humidity was significantly suppressed compared to non-methylated polymer matrix membranes. From this observation it is concluded that non-esterified, free carboxyl groups present in the cutin polymer matrix significantly contribute to the effect of humidity on cuticular water permeability. These and other polar groups sorb water, which in turn increases the water permeability of polar domains of the cuticle. This humidity-sensitive, polar path of cuticular water permeability is arranged in parallel with the major, dominating and humidity-independent, non-polar path of cuticular water permeability formed by the lipophilic wax components of the cuticle. This conclusion is supported by the fact that cuticular transpiration can be increased by orders of magnitude upon (i) wax extraction, (ii) increase in temperature or (iii) the action of plasticizers, none of which influenced or only marginally influenced the permeability of inorganic ions penetrating plant cuticles across humidity-sensitive polar pores.     

Stomatal sensing of the environment

The effects of environmental factors on stomatal behaviour are reviewed and the questions of whether photosynthesis and transpiration eontrol stomata or whether stomata themselves control the rates of these processes is addressed. Light affects stomata directly and indirectly. Light can act directly as an energy source resulting in ATP formation within guard cells via photophosphorylation, or as a stimulus as in the case of the blue light effects which cause guard cell H⁺ extrusion. Light also acts indirectly on stomata by affecting photosynthesis which influences the intercellular leaf CO₂ concentration ( C _i). Carbon dioxide concentrations in contact with the plasma membrane of the guard cell or within the guard cell acts directly on cell processes responsible for stomatal movements. The mechanism by which CO₂ exerts its effect is not fully understood but, at least in part, it is concerned with changing the properties of guard cell plasma membranes which influence ion transport processes. The C _i may remain fairly constant for much of the day for many species which is the result of parallel responses of stomata and photosynthesis to light. Leaf water potential also influences stomatal behaviour. Since leaf water potential is a resultant of water uptake and storage by the plant and transpirational water loss, any factor which affects these processes, such as soil water availability, temperature, atmospheric humidity and air movement, may indirectly affect stomata. Some of these factors, such as temperature and possibly humidity, may affect stomata directly. These direct and indirect effects of environmental factors interact to give a net opening response upon which is superimposed a direct effect of stomatal circadian rhythmic activity.     

Some Factors Affecting Survival of Desiccation by Infective Juveniles of Orrina phyllobia

The survival of desiccation by J4 Orrina phyllobia was examined at controlled relative humidities. When nematodes were transferred from water to air at 10% relative humidity (rh), 80% died within 30 minutes. When nematodes were transferred from water to air with rh at 70% or greater for ca. 15 minutes prior to being transferred to 10% rh, more than 90% of them survived desiccation. This phenomenon is referred to as preconditioning and occurred at much faster rates (2-30 minutes) than has been observed for other nematode species (24 hours). Differences in preconditioning rates may be due to technique-dependent variations in boundary layer resistance around nematodes during desiccation.     

Effects of air pollutants on pollen

In vivo and in vitro pollen germination and pollen tube growth are affected by air pollutants. The stimulation and inhibition of these pollen characteristics depend on the pollen species as well as on the pollutant and its concentration, the exposure time, the relative humidity during exposure and some other factors. Mitosis, gas exchange, size and chemistry of pollen can also be influenced by air contaminants. Pollen germination and tube elongation differ in their response to air pollution stress, and both are more susceptible in vitro compared to the in vivo situation. Some possible mechanisms of action are reported in this review study. The effects of air contaminants on pollen are discussed in relation to sexual reproduction, gametophytic selection and adaptation to stress. Pollen may be used as sensitive biological indicators of pollution     

Mitogenic and mutagenic effects of ionized air on Allium fistulosum L

In the apical meristem of Allium fistulosum, the relationship between peroxide lipid oxidation, antioxidant activity, proliferative processes, the yield of chromosomal aberrations and duration the exposure to ionized air was studied. Under the influence of air oxygen ions, superoxide dismutase and catalase activities increased, proliferative processes were stimulated, and shifts occurred in the process of lipid peroxidation in cells of A. fistulosum. When these cells were treated with air oxygen for 40 min, hydrogen peroxide and iron sulfate (II) enhanced oxygen biostimulating effect via stimulation of antioxidant enzyme activity and inhibition of lipid peroxidation. Under these conditions, cell proliferation was intensified and the yield of chromosomal aberrations was reduced in A. fistulosum rootlets. When the time of seed treatment with ionized air was increased to 80 min, lipid peroxidation was activated, antioxidant enzyme activity was inhibited, and the yield of chromosomal aberration increased in seedlings. It was concluded that the biostimulating activity of ionized air was mediated by active oxygen species generated in the cell. The accumulation of TBA(thiobarbituric acid)-reactive products was shown to be related to a decrease in antioxidant enzyme activity and an increase in the yield of chromosomal aberrations. It is emphasized that the mutagenic effect of ionized air is associated with generating conditions that support Fenton reaction and OH-radical formation in the cell.     

Effects of irrigation and air humidity preconditioning on water relations, growth and survival of Rosmarinus officinalis plants during and after transplanting

The effect of different irrigation and air humidity conditioning treatments on the morphological and physiological responses of Rosmarinus officinalis in nursery conditions was investigated in order to evaluate the degree of hardening resulting from these conditions. Rosmarinus officinalis seedlings were pot-grown during 4 months in two greenhouses (nursery period), in which two irrigation treatments were used (control and deficit). In one of these greenhouses, air humidity was controlled using a dehumidifying system (low humidity), in the other greenhouse the air conditions were not artificially modified (control humidity). After the nursery period, the plants of all treatments were transplanted and well watered (100% water holding capacity for 1 month, transplanting period). After this period, they received no water (establishment period). At the end of the nursery period it was seen that deficit irrigation had altered the morphology of the R. officinalis plants by reducing plant height, stem diameter, leaf area, total dry weight, and root length, while humidity influenced the parameters related with plant water relations. Low air humidity and deficit irrigation-induced tissue dehydration and lower stomatal conductance values (gs). The plants subjected to deficit irrigation developed leaf osmotic adjustment, which was maintained during the transplanting period. At that time, the plants that had been exposed to deficit irrigation and low humidity showed efficient stomatal regulation (lower gs values). After transplanting and during the establishment period, these plants showed a better water status (higher psil and gs values). Their post-planting survival rate improved as a result of acclimation processes.     

Physical effects of negative air ions in a wet sauna

 The physical effects of negative air ions on humans were determined in an experimental sauna room equipped with an ionizer. Thirteen healthy persons took a wet sauna bath (dry bulb temperature 42° C, relative humidity 100%, 10 min exposure) with or without negative air ions. The subjects were not told when they were being exposed to negative air ions. There were no differences in the moods of these persons or changes in their blood pressures between the two saunas. The surface temperatures of the foreheads, hands, and legs in the sauna with negative ions were significantly higher than those in the sauna without ions. The pulse rates and sweat produced in the sauna with ions were singificantly higher than those in the sauna without ions. The results suggest that negative ions may amplify the effects on humans of the sauna. Received: 31 March 1995 / Revised: 25 July 1995 / Accepted: 26 July 1996     

The effect of negative air ions on the respiratory organs and blood

The effect of ionized air containing negatively charged ions at a concentration of 320000–350000 ions/cm³ inhaled by rats was studied. It was demonstrated that the inhalation of negative air ions for 60 min activated the secretion of goblet cells without impairing the tracheal mucosa and changing the protein profile of bronchoalveolar lavage. It was also found that the level of spontaneous production of reactive oxygen species by unfractionated blood cells increased after the action of negative air ions in both males and females. However, the intensity of their generation induced by opsonized zymosan increased only in females. Different sensitivities of the female and male blood antioxidant enzymes—superoxide dismutase and glutathione reductase—to negative air ions were observed. These results allow the effect of negative air ions on the respiratory organs and blood to be interpreted as priming and weak activation via a direct action on the mucosa of primary target respiratory organs and then on the blood.     

Time-resolved infrared studies of light-induced processes in plant thylakoids and bacterial chromatophore membranes. Evidence for the function of water molecules and the polypeptides in energy dissipation

Spinach thylakoids and chromatophores from the photosynthetic bacterium Rhodopseudomonas capsulata were investigated by means of time-resolved infrared spectroscopy, using thin water-containing membrane films which fully maintained their photochemical activity. Upon flash excitation, reversible infrared absorbance changes were obtained and their difference spectra were recorded. In spinach thylakoids, these transient signals could be described by a sum of two exponential decay functions with half-times of about 2 and 30 ms, respectively. They were insensitive to the addition of benzyl viologen, ferricyanide or ferricyanide + DCMU. They are ascribed by their dependence on intensity and wavelength range of the actinic flash to processes in the antenna pigment-protein complexes. In chromatophores from photosynthetic bacteria, similar infrared signals in the millisecond time range were obtained. Their spectral distribution was investigated for three mutants of the photosynthetic bacterium and is different for membranes lacking carotenoids. Both signals, in thylakoids and chromatophores, reflect the proportion of absorbed flash energy which is neither channelled to the reaction center nor emitted as light, but is dissipated through radiationless decay. A common feature of the difference spectra from spinach thylakoids and bacterial chromatophores are bands identified by deuteration as being due to H₂O. Some bands are interpreted in terms of water going transiently from the hydrogen-bonded to the free state. Other bands are assigned to the polypeptides of the light-harvesting complexes, and thus indicate their participation in energy dissipation. Membranes from photosynthetic bacteria containing a photochemical reaction center show a distinct slow signal component decaying in about 1 s. It saturates at low flash intensity and is abolished upon chemical oxidation of the primary electron donor. Two bands in the difference spectrum of this component are tentatively assigned to the ester C = O and keto C = O vibrations of photooxidized bacteriochlorophylls in the reaction center. The data suggest that chromophoric and non-chromophoric infrared absorbance changes contribute to the difference spectra, and thus may represent a clue to the processes at the active sites of polypeptides in photosynthesis.     

空气湿度与土壤水分胁迫对紫花苜蓿叶表皮蜡质特性的影响

选用2个抗旱性不同的紫花苜蓿品种,敖汉(强抗旱)和三得利(弱抗旱),设置空气湿度(45%-55%和75%-85%)和土壤水分胁迫(75%和35%田间持水量)处理,分析紫花苜蓿叶表皮蜡质含量、组分及晶体结构、气体交换参数、水势及脯氨酸含量的变化规律。结果表明,单独土壤水分胁迫时,紫花苜蓿叶表皮蜡质晶体结构及蜡质总量无显著变化;敖汉蜡质组分中烷类、酯类含量增加,醇类含量下降;三得利醇类含量下降,烷类、酯类含量变化不显著。低空气湿度胁迫时,两品种蜡质总量无显著变化,烷类和酯类含量显著增加,醇类含量显著下降,叶表皮片状蜡质晶体结构熔融呈弥漫性,扩大了对叶表面积的覆盖,其蒸腾速率显著低于正常湿度。复合胁迫处理时,叶表皮片状蜡质晶体结构继续呈弥漫性,烷类、酯类、未知蜡质组分含量均高于单独胁迫处理,醇类含量最低,而蜡质总量除三得利显著高于对照外,其余均无显著差异。紫花苜蓿叶表皮蜡质各组分含量(除醇类)及蜡质总量与光合速率呈显著负相关,与蒸腾速率无显著相关关系。蜡质总量与叶水势呈显著正相关。总体上,敖汉蜡质总量显著高于三得利,蜡质组分中烷类物质的增加有助于提高植株的抗旱性。在复合胁迫下,强抗旱品种主要通过气孔因素控制水分散失,而弱抗旱品种通过气孔和非气孔因素共同控制植物水分散失。     

The photochemistry of some main chain liquid crystalline 4,4'-stilbene dicarboxylate polyesters.

Several aspects of the photochemistry and photophysics of four main chain liquid crystalline polyesters with a rigid trans-stilbene 4,4'-dicarboxylate mesogen as chromophore and flexible spacer groups are reported. The three polymers with the longest 'spacer' groups are liquid crystalline at room temperature, two have smectic phases. Chromophore aggregation has a dramatic effect on the photophysics and photochemistry of these polymers. Each of the polymers in poor solvents or as films has greatly perturbed UV-Vis absorption and fluorescence spectra due to aggregation of the stilbene chromophore. These effects are more pronounced upon annealing above the glass transition temperature, T(g), and in the mesophase. Film fluorescence is excitation wavelength dependent and is suppressed at elevated temperatures. The stilbene 'environment' in both films and solution is clearly heterogeneous and energy transfer processes relatively slow. The dominant photochemical reaction upon direct excitation above 300 nm is 2 + 2 photocycloaddition rendering polymer films insoluble. No significant trans-to-cis photoisomerization can be detected upon initial irradiation of the polymer films. There is evidence for the formation of aldehyde and carboxylate functionality upon irradiation in the presence of air. Loss of the aggregate UV-Vis absorption and fluorescence occurs during irradiation. Difference UV-Vis spectra of irradiated films suggest preferential initial consumption of dimeric aggregates. Loss of stilbene UV-Vis absorption upon irradiation above 300 nm can be partly photoreversed upon subsequent 254 nm irradiation. The rate of stilbene chromophore loss from films increased significantly above Tg and in the smectic phase above room temperature.     

Evaporation rate enhancement of water with air ions from a corona discharge

Space charges (air ions) produced by a single point-to-plane corona electrode system were used to study the enhancement in the evaporation rates of water at three ion current levels. The maximum evaporation rates of 0.019 and 0.017 g·min^?1 were observed at a 1 cm electrode gap for negative and positive air ions, respectively. The cumulative evaporation rates were linear with time and an ion-enhanced rate was about 4 times greater than the control. The current density distribution measurements agreed fairly well with those predicted from the Warburg law. The principal driving force for the observed evaporation enhancement was an ion drag phenomenon which created vortex motions in water when air ions were subjected to an externally applied electric field. Theoretical considerations from derived relationships in fluid mechanics demonstrate that the mass transfer coefficient is higher for positive than negative ions of the same current strength because of the mobility difference between the charges in the medium.