Low-molecular-weight organoiodine and organobromine compounds released by polar macroalgae – The influence of abiotic factors

The influence of temperature, light, salinity and nutrient availability on the release of volatile halogenated hydrocarbons was investigated in the Antarctic red macroalgal species Gymnogongrus antarcticus Skottsberg. Compared to standard culture condition, an increase in the release rates of iodocompounds was generally found for the exposure of the alga to altered environmental conditions. Macroalgae exhibited higher release rates after adaptation for two months to the changed factors, than after short-term exposure. Monitoring the release rates during a 24 h incubation period (8.25 h light, 15.75 h darkness) showed that changes between light and dark periods had no influence on the release of volatile halocarbons. Compounds like bromoform and 1-iodobutane exhibited constant release rates during the 24 h period. The formation mechanisms and biological role of volatile organohalogens are discussed. Although marine macroalgae are not considered to be the major source of biogenically-produced volatile organohalogens, they contribute significantly to the bromine and iodine cycles in the environment. Under possible environmental changes like global warming and uncontrolled entrophication of the oceans their significance may be increase.     

Continuing damage to rat retinal DNA during darkness following light exposure

The damaging effects of visible light on the mammalian retina can be detected as functional, morphological or biochemical changes in the photoreceptor cells. Although previous studies have implicated short-lived reactive oxygen species in these processes, the termination of light exposure does not prevent continuing damage. To investigate the degenerative processes persisting during darkness following light treatment, rats were exposed to 24 h of intense visible light and the accumulation of DNA damage to restriction fragments containing opsin, insulin 1 or interleukin-6 genes was measured as single-strand breaks (ssb) on alkaline agarose gels. With longer dark treatments all three DNA fragments showed increasing DNA damage. Treatment of rats with the synthetic antioxidant dimethylthiourea prior to light exposure reduced the initial development of alkali-sensitive strand breaks and allowed significant repair of all three DNA fragments. The time course of double-strand DNA breaks was also examined in specific genes and repetitive DNA. Nucleosomal DNA laddering was evident immediately following the 24 h light treatment and increased during the subsequent dark period. The increase in the intensity of the DNA ladder pattern suggests a continuation of enzymatically mediated apoptotic processes triggered during light exposure. The protective effects of antioxidant suggests that the light-induced DNA degradative process includes both early oxidative reactions and enzymatic processes that continue after cessation of light exposure.     

Time-dependent responses of wounded human skin fibroblasts following phototherapy

BACKGROUND AND OBJECTIVE: The penetration and distribution of laser light in target tissue is dependent on the wavelength of the light. One problem with most of the published data on laser irradiation is that most studies do not record the duration between the exposure and the evaluation. This study aimed to establish if the dose, wavelength or duration of effect (1h or 24h) influences the biological responses of irradiated fibroblasts. MATERIALS AND METHODS: The study established cellular responses of normal and wounded human skin fibroblasts to helium-neon (632.8 nm), diode (830 nm) and Nd:YAG (1064 nm) laser irradiation using one exposure of 5 J/cm(2) or 16 J/cm(2) on day 1 and again on day 4. Cellular responses to laser irradiation were evaluated by measuring changes in cell viability (ATP viability and caspase 3/7 activity) and cell proliferation (ALP enzyme activity and bFGF expression), 1h and 24h post irradiation. RESULTS: Wounded cells exposed to 5 J/cm(2) using 632.8 nm showed an increase in ATP viability after 1h, a decrease in caspase 3/7 activity after 24h and an increase in cell proliferation after 24h. The results suggest that changes in parameters such as ATP viability should be observed directly after laser irradiation (1h) whereas other parameters such as caspase 3/7 activity, bFGF expression and ALP enzyme activity should be measured at least 24h after the final exposure. CONCLUSION: This study confirms that the duration of effect should be included as one of the main laser parameters when reporting on the effects of laser irradiation. It is important to establish time-dependent responses as the results may provide an understanding of the cellular responses following laser irradiation.     

Changes in tumor interstitial pressure induced by photodynamic therapy.

This study has examined the changes in tumor interstitial pressure exhibited during and after photodynamic therapy (PDT). The kinetics of these changes are marked by an initial decrease, followed by a rapid rise in tumor interstitial pressure. We have also employed two inhibitory agents to evaluate the different components of the pressure curve. Specially designed pressure chambers were seeded with chondrosarcoma and implanted subcutaneously in rats. Animals were injected with 0-50 mg/kg Photofrin II (i.v.) 7 days post-implantation and tumors were exposed to 0-540 J/cm2 630 nm 24 h later. Interstitial pressure was monitored via a transducer connected to the implanted chamber. Additional groups of animals were injected with either indomethacin (an inhibitor of thromboxane synthesis) or Ketanserin (a serotonin antagonist) before light treatment. Porphyrin doses of 10 mg/kg and above (135 J/cm2), or light doses of 135 J/cm2 and above (25 mg/kg Photofrin II) were effective in modifying interstitial pressure. Porphyrin doses greater than 25 mg/kg, or light doses greater than 270 J/cm2 produced no further increases in interstitial pressure. Animals given indomethacin (10 mg/kg i.p.) exhibited the initial decrease in pressure during light treatment, but showed no increase past baseline levels. Animals given Ketanserin (10 mg/kg i.p.) demonstrated no decrease in pressure during PDT, but showed the same elevations in pressure as controls. This suggests that two independent mechanisms account for the different components of the pressure curve, and that serotonin release may occur during PDT.     

Monitoring of headspace total volatile basic nitrogen from selected fish species using reflectance spectroscopic measurements of pH sensitive films

The release of amines from decomposing fish such as trimethylamine (TMA), dimethylamine (DMA) and ammonia, collectively known as total volatile basic nitrogen (TVB-N), are in high enough concentrations in headspace to be monitored by a colour change in a pH-sensitive sensor. A method developed here uses a pH indicator dye physically trapped in a cellulose polymer film to respond to the headspace TVB-N released from selected fish species during spoilage. Two species were selected for analysis on the basis of economic importance and the levels of volatile amines released were followed with time using uv/vis reflectance spectroscopic measurements. The results show that there is a significant increase in the TVB-N content in the headspace of fish samples after an incubation period of 8-12 h for cod and 12-15 h for orange roughy.     

INHIBITORY EFFECT OF CONTINUOUS FAR-RED PREIRRADIATION ON CHLOROPHYLL ACCUMULATION OF PHARBITIS NIL COTYLEDONS

Abstract The effect of continuous far-red (FR) preirradiation on the accumulation of chlorophyll (Chi) during a white light (WL; 500 lx) period was examined using Pharbitis nil cotyledons. The saturation level of accumulated Chi attained after prolonged exposure to WL was always lowered by continuous FR irradiation preceding the WL. The rate of Chi accumulation during the rapid increase phase (operationally defined as the amount of Chi accumulated during a 24-h WL period) was enhanced by preirradiation with up to 36 h of FR. However, when the FR preirradiation lasted longer, the rate was reduced below the dark control level. Even FR preirradiation of up to 36 h fully reduced the rate of Chi accumulation under WL when 36 h or longer darkness was spaced between the FR and the WL period.     

Effect of stratospheric ozone depletion and enhanced ultraviolet radiation on marine bacteria at Palmer Station, Antarctica in the early austral spring

We investigated the interactions between ozone-depleted air masses and subsequent changes in UVB on marine bacterial abundance and production at Palmer Station, Antarctica from September to November 1999. During periods of low total column ozone (TCO), bacterial cell concentrations declined by 57%. Photoinhibition of bacterial [(3)H]-leucine (Leu) and [(3)H]-thymidine (TdR) incorporation due to UVB was greatest during periods of low TCO in September and early October. During diel ( approximately 28 h) exposure experiments, light treatment samples exhibited >75-100% inhibition of TdR incorporation by mid-afternoon. Leu incorporation exhibited maximum inhibition (50-100%) at sunset and early evening hours. Leu and TdR incorporation in light treatment samples did not exhibit recovery during subsequent periods of darkness. Bacterial Leu and TdR incorporation rates were inversely related to Setlow Dose during a period of recovery from low TCO. These data further suggested a threshold exposure below which bacterial Leu and TdR incorporation recovered rapidly. Recovery of bacterial production after acute Setlow Dose exposures lagged recovery of TCO and was linearly related to TCO measured 2 days previously. This lag in recovery may have resulted from the energetically expensive repair of UVR-induced DNA damage acquired during periods of low TCO.     

Photoinhibitory light-induced changes in the composition of chlorophyll-protein complexes and photochemical activity in photosystem-I submembrane fractions

The effects of irradiation on photosystem (PS)-I submembrane particles using intense white light (2000 micoE x m(-2) x S(-1)) at chilling temperature (4 degrees C) were studied. PSI-dependent oxygen uptake activity was stable during the first 3 h of photoinhibitory illumination in the presence of added superoxide dismutase (SOD). Without added SOD, the oxygen uptake almost doubled during this period, presumably due to the denaturation of native membrane-bound SOD or its release from the PSI membranes. The total chlorophyll (Chl) content and the magnitude of light-induced absorbance changes at 830 nm (deltaA830) were also barely affected during the first 3-3.5 h of photoinhibitory treatment. However, further exposure to strong light markedly accelerated Chl breakdown followed by a decline in oxygen uptake rate and deltaA830. This corresponded with the disappearance of the bands attributed to PsaA/B polypeptides on electrophoretic gels. Despite the invariant maximum magnitude of deltaA830 during the first 3-3.5 h of photoinhibitory treatment, the light-response curves of P700 oxidation gradually altered, demonstrating a several-fold increase in the ability of weak actinic light to oxidize P700. The major Chl a-protein 1 (CP1) band gradually disappeared during the first 4 h of light exposure with a corresponding increase in the Chl content of a band with lower electrophoretic mobility ascribed to the formation of oligomers containing CP1, light-harvesting complex I (LHCI)-680 and LHCI-730. This aggregation of Chl-protein complexes, likely caused by photoinhibitory-induced cross-linking favoring light harvesting, is proposed to explain the enhanced capacity of weak light to oxidize P700 in photoinhibited PSI submembrane fractions compared with untreated ones.     

The role of external polyamines on photosynthetic responses, lipid peroxidation, protein and chlorophyll a content under the UV-A (352nm) stress in Physcia semipinnata

Physcia semipinnata was exposed to UV-A (352nm) and visible light (210, 800 and 2000mW/cm2) for 30min, 1, 2, 24, and 48h to seek the alterations in the PSII photosynthetic quantum yield, in response to radiation. Chlorophyll a fluorescence did not influence exposure to light, 210, 800 and 2000mW/cm2. Significant alterations of the photosynthetic quantum yield ratio occurred in response to increase in UV-A exposure time. The photosynthetic quantum yield ratio decreased in P. semipinnata following exposure to UV-A for 24 and 48h. The thalli of P. semipinnata treated with 1mM polyamine were not influenced during the exposure to UV-A for 24 and 48h. It was also found that exogenously spd added samples had higher chla content than spm and put added samples. In this study, we showed that lipid peroxidation levels between UV-A-treated samples and exogenously polyamine treated samples that were previously exposed to UV-A for 24 and 48h were significantly decreased. This result is the first record to indicate that external polyamines might have some protective role on photosystem II and membrane against UV-A stress.     

THE PHOTODYNAMIC EFFECTS ONV–79 CHINESE HAMSTER CELLS

Abstract— Holding of acriflavine sensitizedV–79 cells in growth medium before visible light exposure decreases inactivation by visible light. The decrease depended upon the period of holding, indicating that there was release of cellular dye during this period. Exposures to visible light were done in two conditions: (a) with no dye in the medium during visible light exposure (washed) and (b) with dye in the medium during exposure (unwashed). Caffeine was found to slightly increase the sensitivity of the cells to visible light in the washed condition, whereas, in the unwashed condition no such effect was observed. Interaction studies with far UV did not reveal any correlation between photodynamic damage and UV damage. Visible light exposure of acriflavine sensitized cells was found to be mutagenic, as studied from the induction of 8-azaguanine resistant mutants. Inhibition of singlet oxygen production by sodium azide suppressed the induction of mutants. All these, taken together, have been discussed with respect to the relative importance of DNA and non-DNA damage in the photodynamic action of acriflavine.     

The Effects of Thrombocytopenia on Vessel Stasis and Macromolecular Leakage after Photodynamic Therapy Using Photofrin

Abstract— Several studies have reported thrombus formation and/or the release of specific vasoactive eicosanoids, suggesting that platelet activation or damage after photodynamic therapy (PDT) may contribute to blood flow stasis. The role of circulating platelets on blood flow stasis and vascular leakage of macromolecules during and after PDT was assessed in an intravital animal model. Sprague-Daw-ley rats bearing chondrosarcoma on the right hind limb were injected intravenously (i.v.) with 25 mg/kg Photofrin 24 h before light treatment of 135 J/cm² at 630 nm. Thrombocytopenia was induced in animals by administration of 3.75 mg/kg of rabbit anti-rat platelet antibody i.v. 30 min before the initiation of the light treatment. This regimen reduced circulating platelet levels from 300000/mm³ to 20000/mm³. Reductions in the luminal diameter of the microvasculature in normal muscle and tumor were observed in control animals given Photofrin and light. Venule leakage of macromolecules was noted shortly after the start of light treatment and continued throughout the period of observation. Animals made thrombocytopenic showed none of these changes after PDT in either normal tissues or tumor. The lack of vessel response correlated with the absence of thromboxane release in blood during PDT. These data suggest that platelets and eicosanoid release are necessary for vessel constriction and blood flow stasis after PDT using Photofrin.     

Sodium and potassium in the lens after exposure to radiation in the 300 nm wavelength region

The possible change in sodium and potassium concentration in the lens after an in vivo exposure to radiation in the 300 nm wavelength region was investigated. Both lenses from 12 reference rats and from 80 unilaterally exposed rats were examined. The exposed rats were sacrificed in four groups: 6, 24, 72 and 168 h after exposure. The lenticular cation contents were determined using atomic absorption spectrophotometry. In exposed lenses the concentration of sodium increases whereas that of potassium decreases as the time after exposure increases. The rates of concentration change decrease as the time after exposure increases. The increase in sodium precedes the decrease in potassium. Furthermore, a slight increase in the concentration of sodium is registered, as the time after exposure increases, in the non-exposed contralateral lenses. The registered changes are believed to reflect the water balance in the lenses.     

Phytochemical analysis and in vitro cytotoxic activity of volatiles from Astragalus corniculatus

The volatile fractions from Astragalus corniculatus Bieb., cultivated and collected wild, were analyzed at three different phenological phases for the first time. GC/MS analysis showed that the volatile fractions contain hydrocarbons, butyl ethers, acids, alcohols, esters, aldehydes, ketones, terpenes. These fractions were tested for cytotoxic activity in a panel of human tumor cell lines after 48 h, using the MTT-dye reduction assay. Throughout the cytotoxicity evaluation the fraction derived from the flowering phase of wild type plant was found to exert the most prominent cytotoxic activity, which could be ascribed to the high content of hydrocarbons and squalene in particular. Furthermore, the mechanistic elucidation of the mode of action of this volatile fraction in SKW-3 cells revealed that the observed activity is mediated by induction of necrotic type cell death as evidenced by the smear patterns of DNA following a 24 h exposure period.     

大同烟煤增压富氧燃烧过程中硫、氯和氟的析出特性

利用高压热重结合傅里叶红外研究了大同烟煤在增压富氧燃烧过程中硫、氯和氟的释放行为,主要考察压力对其析出特性的影响。实验结果表明,压力的改变对煤中硫、氯和氟的迁移转化均有显著影响。随着压力的升高,黄铁矿硫向COS等中间产物的转化率逐渐增加,导致SO2的收率逐步上升,但在3 MPa时,燃煤SO2收率却有所降低。此外,压力升高后反应气氛中CO分压的增加促进了COS的生成,导致其收率逐渐上升。因为煤中有机氯析出和转化与挥发分的释放密切相关,所以高压下挥发分释放量的增加使得煤中有更多的有机氯析出并转化为HCl,而且压力升高后,挥发分燃烧速率和温度的升高促进了无机氟化物分解,HF生成量相应增加。此外,高压下水解反应的强化也提高了HF的收率。     

The influence of temperature on photodynamic cell killing in vitro with 5-aminolevulinic acid

Cell survival was investigated after exposing cells in vitro to different temperatures before or after photodynamic therapy with 5-aminolevulinic acid. The photodynamic process was found to be temperature dependent. Cells exposed for 1h to 41 degrees C before light exposure or to 7 degrees C after light exposure showed decreased survival. Furthermore, the photobleaching rate of protoporphyrin IX in the cells was found to increase with increasing temperature during the light exposure. Thus, the photodynamic effect with 5-aminolevulinic acid may be enhanced by heating the tumour area before, and by cooling it immediately after the treatment.     

Evaluation of the Storage Conditions and Type of Cork Stopper on the Quality of Bottled White Wines

The effects of different storage conditions, light exposure, temperature and different commercially available cork stoppers on the phenolic, volatile and sensorial profile of Verdejo wines were studied. Two natural corks of different visual quality and a microgranulated cork stopper were investigated over one year at two different storage conditions. One simulating light exposure and temperature in retail outlets and the other simulating optimal cellar conditions (darkness and 12 °C). The wines stored under commercial conditions showed greater losses of total and free SO₂ and higher levels of brown-yellowish tones, related to the oxidation of flavan-3-ols. Although these wines underwent a decrease in the total content of stilbenes, a significant increase in trans-piceid was observed. In addition, these wines suffered important changes in their volatile and sensory profile. Volatile compounds with fruity and floral aromas decreased significantly, while volatile compounds related to aged-type characters, as linalool oxides, vitispirane, TDN or furan derivatives increased. Wines stored in darkness at 12 °C underwent minor changes and their sensory profiles were similar to wine before bottling. The high-quality natural corks and microgranulated corks better preserved the quality of the white wines from a sensory point of view. These results showed that temperature and light exposure conditions (diffuse white LEDs and 24 ± 2 °C) in retail outlets considerably decrease the quality of bottled white wines and, consequently, their shelf life, due to the premature development of aged-type characters.     

Light-induced apoptosis involves a defined sequence of cytoplasmic and nuclear calcium release in AlPcS4-photosensitized rat bladder RR 1022 epithelial cells

Oxidative stress induced by light activation of photosensitizers is regarded to have a role in triggering cell death pathways during photodynamic therapy (PDT). Reactive oxygen species have been proposed to act as signal transduction molecules activating downstream reactions that lead to apoptosis. Mainly debated is the cooperating role of other signaling systems like calcium or pH. The present work contributes to this discussion by studying PDT effects in cell cultures of rat bladder epithelial cells for the hydrophilic tetrasulfonated aluminum phthalocyanine (AlPcS4). Cells were coincubated with the photosensitizer and the calcium-sensitive probe Fluo-3. The light-induced reactions were analyzed with a confocal laser scanning microscope. The dynamics of the process during light activation was observed with subcellular resolution. A transient calcium elevation during the irradiation process was detected, especially in the cell's nuclei, followed by a more sustained increase. The evaluation of the energy-dose-dependent phototoxicity after an incubation time with the photosensitizer of 1 and 24 h, showed enhanced phototoxicity when the drug was present for 24 h. Surprisingly, stimulation of cell proliferation was observed at very low light doses (at 0.2 J/cm2) when the drug was incubated for 24 h (cell viability 160%). Induction of apoptosis could be observed after irradiation with fluences between 1 and 3 J/cm2. Apoptotic cells were identified with fluorescein isothiocyanate-labeled Annexin V, which binds to phosphatidylserine after its translocation to the outer plasma membrane. In the presence of the antioxidant pyrrolidinedithiocarbamate the transient calcium elevation was totally inhibited, as was the subsequent translocation of PS. In contrast, N-acetyl-L-cysteine did not suppress the transient calcium increase. Our data might be consistent with calcium regulated processes during AlPcS4-PDT and the involvement of oxygen radicals.     

UVA‐Induced DNA Damage and Apoptosis in Red Blood Cells of the African Catfish Clarias gariepinus

Ultraviolet‐A light (UVA)‐induced DNA damage and repair in red blood cells to investigate the sensitivity of African catfish to UVA exposure is reported. Fishes were irradiated with various doses of UVA light (15, 30, and 60 min day⁻¹ for 3 days). Morphological and nuclear abnormalities in red blood cells were observed in the fish exposed to UVA compared with controls. Morphological alterations such as acanthocytes, crenated cells, swollen cells, teardrop‐like cells, hemolyzed cells, and sickle cells were observed. Those alterations were increased after 24 h exposure to UVA light and decreased at 14 days after exposure. The percentage of apoptosis was higher in red blood cells exposed to higher doses of UVA light. No micronuclei were detected, but small nuclear abnormalities such as deformed and eccentric nuclei were observed in some groups. We concluded that exposure to UVA light induced DNA damage, apoptosis, and morphological alterations in red blood cells in catfish; however, catfish were found to be less sensitive to UVA light than wild‐type medaka.