摘要:

AbstractThe self‐sensitized photooxidation ofmeso‐diphenylhelianthrene to its endoperoxide was kincticallv examined. It is recommendable as a convenient, reliable, and wavelength independent actinometer for the visible wavelength range. The calibration values, the actinometric procedure and the evaluation method are given in det

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1983.tb04526.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractSeveral effects of hematoporphyrin derivative (HpD) and light on NHIK 3025 cellsin vitrowere studied. The treatment resulted in a partly repairable reduction of the rate of thymidine incorporation into DNA, a division delay, a reduced rate of protein synthesis, a reduced rate of active cellular uptake of α‐aminoisobutyrate, a reduction in the colony‐forming ability and an increased permeability of the cell membrane to chromate. Thymidine incorporation was by far the most sensitive parameter studied. However, comparison of the photodynamic effects after 1 and 18 h incubation with HpD prior to irradiation indicated that neither the reduced rate of DNA synthesis nor any of the other observed effects was the main primary cause of cell inactivation under all conditions. Several of the effects, such as increased permeability of the cell membrane to chromate, reduction in the rate of protein synthesis and reduction in the rate of repair of the damage to the mechanism of DNA synthesis, were clearly of secondary nature. When seen in relation to cellular survival, membrane damage was more important after short incubation times with HpD than after long incubation t

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1983.tb04527.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractMouse 3T3 cells irradiated with ultraviolet light synthesize DNA containing sites sensitive to the single‐strand specific SI nuclease. The appearance of these sites correlates well with the presence of discontinuities in nascent strands, detected by the methodology of sedimentation in alkaline sucrose gradient. Thus, both the sites sensitive to SI nuclease and the discontinuities in nascent strands (i) are stabilized by caffeine; (ii) are no longer formed late after irradiation and (iii) disappear faster when a certain UV fluence is split into two fluences whose sum equals the single fluence. Moreover, the recovery in synthesizing DNA without SI sensitive sites is not dependent on excision repair of pyrimidine dimers or on continuous DNA synthesis. These SI sensitive sites are exclusive of replicative structures of irradiated cells and should correspond to stretches of single‐strand DNA (gaps) formed during replicat

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1983.tb04528.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractTriplet absorption spectra, extinction coefficients (ɛT), decay rates (K1), oxygen quenching rates(kq)and intersystem crossing yields (φT) for 3‐carbethoxypsoralen (3‐CPs). 8‐methoxypsoralcn (8‐MOP) and 5‐methoxypsoralen (5‐MOP) in methanol are reported. For 8‐MOP and 3‐CPs corresponding values are also reported with water as the solvent. Some photophysical data are also reported for 5‐MOP in water, but ɛTand φTwere not obtained.The phosphorescence spectra for these furocoumarin derivatives in ethanol at 77 K are reported together with the corresponding lowest triplet energy and lifetime. The values of the various photophysical properties obtained are compared with values reporte

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1983.tb04529.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractA wild‐typeEscherichia coliK‐12 strain was irradiated with broad‐band near‐ultraviolet radiation (from Black‐Light Blue fluorescent lamps) and after holding at 37°C for various times in a complex recovery medium, was assessed for viability on either complex medium (YENB) or minimal medium containing a high inorganic salt content. A near‐ultraviolet radiation fluence was used which reduced the surviving fraction to approximately 10% when assessing for viability on the complex medium plates. A near‐ultraviolet radiation induced sensitivity to inorganic salt was observed which was largely recoverable by holding treated cells in a complex recovery medium. The majority of the recovery process occurred in the initial 2 h post‐irradiation holding period. No inhibition of the recovery process was produced by adding chloramphenicol (40 μg/ml) or penicillin G (11 units/ml) to the recovery medium, indicating that neither protein synthesis nor cell wall synthesis, respectively, were required for recovery. However, by adding bacitracin, an antibiotic which acts in part by inhibiting membrane synthesis, to the recovery medium, an effectonrecovery from salt sensitivity was observed. At the concentrations of bacitracin used (0.6 and 0.2 units/ml), little or no effect was observed on unirradiated cells, but both concentrations decreased the amount of recovery of irradiated cells. These results demonstrate that recovery from near‐ultraviolet radiation‐induced salt sensitivity occurs, it is independent of cell growth and the effect of bacitracin suggests that membrane synthesis may be

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1983.tb04530.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractThe hairless mouse has been used as an experimental model for photocarcinogenesis for about 20 years. Although the carcinogenesis action spectra for mice and man are not known, acute responses to ultraviolet radiation (UVR) in the biologically active UVB and UVC region (wavelengths below 320 nm) can be compared. Vascular response (predominantly edema) action spectra for monochromatic radiation in the Skh:HR‐l (albino hairless) male mouse were determined. These action spectra were found to be very similar to the human erythema action spectrum that had been developed using the same monochromator. The accuracy of this experimentally derived action spectrum was tested with a series of polychromatic source spectra. The mice were exposed to radiation from a long arc Xe lamp filtered by varying thicknesses of Schott WG320 filters, which yielded a wide range of biologically effective spectra. Spectral irradiance measurements, when weighted with the mouse edema and human erythema action spectra and multiplied by the irradiation time required to elicit a threshold response (edema), yielded a constant weighted dose regardless of irradiation spectral quality. The integrated effective dose was approximately 200 J/m2of 297 nm equivalent energy, agreeing with requirements for the monochromatic 297 nm dose in the mice as well as for minimal human erythema. These data suggest a commonality in the UVR chromophores of mice and men as they relate to the acute responses described, and a direct additivity of effectiveness from the UVR components in a polychromatic beam, at least over the portion of the UVR spectrum tested (λ>295 n

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1983.tb04531.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractPrimary cultures of the R3230AC mammary adenocarcinoma were used for pharmacokinetic studies of hematoporphyrin derivative (HPD), a preparation containing several porphyrin species and useful as a photoactivatable anti‐tumor agent. Uptake of HPDin vitrowas shown to be time‐, dose‐ and temperature‐dependent with an apparent plateau reached at 2 ‐ 4 h. An increase in the amount of serum in the medium progressively reduced the amount of HPD taken up by the cells; at a level of 10% serum, uptake of HPD was reduced by>95%. The time‐course of efflux of HPD from these cells demonstrated a complex pattern, with an initial rapid component followed by a more gradual rate of efflux up to 4 h. Assessment of photoradiation‐induced cytotoxicity was performed by a method developed to quantitatively measure trypan blue exclusion. Relative cytotoxicity was determined by use of heat‐killed cells as a standard. At two different concentrations of HPD, cytotoxicity was dependent on light exposure time. The presence of serum, which reduced uptake of HPD was correctable to reduced cytotoxicity. Based on the amount of light exposure to produce 50% cell kill, an order of potency was obtained for HPD>hematoporphyrin>hydroxyethylvinyldeuteroporphyrinin vitro.This order of potency correlated with the relative proportion of hydrophobic components as estimated by HPLC analysis. The results indicate that HPD is an effective cytotoxic agentin vitroin a well‐differentiated mammary ade

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1983.tb04532.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractNoninvasive determinations of the amount of cutaneous blood in the superficial plexus are made from skin reflectance measurements after exposure of human skin to UV radiation. The approach considers the skin as consisting of multiple optically distinct layers, and utilizes a previously experimentally verified optical model that relates the optical properties of these skin layers to skin reflectance. When the UV erythema is concurrently graded by visual inspection, our results show that each subjective grade corresponds to a broad range of values of cutaneous blood, and a wide overlap in blood volumes occurs between different grades. The amount of cutaneous blood increases with the UV dose, and follows a sigmoid threshold relationship. Erythema fades with time, but the rate of decrease in cutaneous blood is volume dependent. The sharpest decrease occurs when the amount of cutaneous blood is within 1.5 ‐ 2.5 times the pre‐radiation volume. Slower decrease occurs when the volume of blood is outside of this ra

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1983.tb04533.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractThe first measurements of the simultaneous photoproduction of hydrogen and oxygen in marine green algae are reported. Eight species in the generaChlamydomonas, ChlorellaandHalochlorocococcumwere tested in CO2‐free seawater. Four of the five species ofChlamydomonaswere able to produce hydrogen in the light after a period of 3 ‐ 4 h of dark anaerobic adaptation. Only one of the twoChlorellaspecies tested was able to photoproduce hydrogen, in trace amounts.Halochlorocococcumfla–9 gave positive results andChlamydomonasspecies (clone f‐9) had a steady‐state rate of hydrogen and oxygen production during irradiation with a stoichiometric ratio near 2:1. The integrated yields of hydrogen and oxygen produced by this species corresponds to about 450 turnovers of the photochemical reaction centers. This number exceeds (by about a factor of 20) the electron‐carrying capacity of the electron transport chain linking Photosystems I and II. These data suggest thatChlamydomonasf‐9 makes seawater a potential substrate for solar hydrogen and oxyg

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1983.tb04534.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractThe formation of singlet oxygen by photodynamic agents is shown to be notably amplified by the combination of UV‐B radiations plus tryptophan in aqueous medium because of the formation of N‐formylkynurenine. a tryptophan photoproduct which is also a good photosensitizer. The biological implication of these effects is discus

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1983.tb04535.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY