摘要:

Abstract–The role of metallothionein (MT) in protecting skin cells against UVB irradiation was investigated. Fibroblast strains from normal adult (HS‐K) and neonatal (NB1RGB) human skins as well as keratinocyte strains from human skin (SV40‐HSK) and newborn Balb/c mouse skin (Pam 212) were exposed to UVB irradiation.The sensitivity of HS‐K and NB1RGB cells to UVB irradiation was similar; those of SV40‐HSK and Pam 212 cells were two‐ and six‐fold as sensitive to UVB irradiation as HS‐K cells, respectively. The HS‐K cells contained the greatest cellular reduced form of glutathione (GSH) levels compared to the three other skin cells: the levels were 13‐, 7‐ and 6‐fold of those in NB1RGB, SV40‐HSK and Pam 212 cells, respectively. These results indicated that the sensitivity of skin cells to UVB irradiation was not always associated with their endogenous GSH levels. In particular, despite the fact that NB1 RGB cells contained a relatively small amount of GSH, they were less sensitive to UVB irradiation.NB1RGB cells contained 4–30 times more MT than those in other skin cells examined. The sulfhydryl residues of MT molecules in the NB1RGB cells were estimated to be mostly unoccupied by metals, suggesting they act in a similar way to those of GSH. Moreover, NB1RGB cells in which the MT content was elevated by dexamethasone (1 μg/mL)or Zn2+(7 μg/mL) treatment were more resistant to UVB irradiation than nontreated ones.These results suggest that, at least in neonatal human skin fibroblasts, MT may play a role in prote

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1994.tb08233.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract–Robertson‐Berger sunburn meter data recorded from August 1992 to May 1993 (Innsbruck, 577 m above sea level, Austria) were compared with measurements taken in previous years. In February and March 1993 instantaneous values on clear days were found to be higher by up to 37% than those registered in previous years (1986–1988). However, in winter/spring 1993 daily totals for all days, averaged over 7 days, were within the range of standard deviation of the previous years (1981–1988). Therefore the cumulative UV‐B exposure of the ecosystem is within the general range of variability even under the record low ozone values in winter/spring 1993, while single peak doses were enhanced sign

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1994.tb08234.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract–We calculated the opsin shift due to the electrostatic interaction between tryptophan or tyrosine residues and the chromophore by the perturbation method for various mutual configurations. The obtained opsin shift maps for these configurations demonstrated that when the above residues reside around the ionone ring side, the positive opsin shift (bathochromic shift) is obtained, and when they reside around the Schiff‐base side, the negative opsin shift (hypsochromic shift) is obtained. These properties hold true, irrespective of the orientation of those residues, indicating that higher order multipoles of the group play a central role. The maximum value of the opsin shift by these groups amounts to several hundred wavenumbers. These results indicate that the location of some of those amino acid residues at proper positions around the chromophore can cause a considerable opsin shift. We also calculated opsin shift maps for the various mutual configurations between a water molecule and the chromophore for compari

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1994.tb08235.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract–An acoustic method is outlined to detect triplet states formed by radical pair recombination in photosyn‐thetic reaction centers. It is based on magnetic field effect on the probability of triplet state formation by recombination. Using a periodically modulated magnetic field in the presence of constant exciting light, a periodic modulation of the triplet state concentration is set in the sample, which is detected through the corresponding modulated heat emission, transduced to acoustic vibration of the gas phase around the sample. This effect is similar to the photoacoustic effect, except that here the light is not modulated. The feasibility of detecting such an effect was proven experimentally, by obtaining a signal from quinone‐depleted reaction centers ofRhodobacter sphaeroides.The signal had twice the frequency of the magnetic field modulation; it was proportional to the light intensity and significantly stronger at the lower temperatures (in the investigated range 113–278 K). No signal was obtained from quinone‐containing reaction centers, which do not produce triplets. A theoretical outline of the effect and the experimental set‐up are described. The “magnitude of the effect was calibrated against ordinary photoacoustic measurements, allowing numerical evaluation of certain parameters of the triplet state (e.g.triplet energy or yield) with the aid of auxiliary information from t

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1994.tb08236.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Abstract–The peroxidative metabolism of TV‐methylcarbazole emits light independently of the presence of oxygen. It is likely that two chemiexcited transients are formed by electron transfer to the activated peroxidase, the cation radical by one electron transfer and a cation biradical by two electron transfer consistent with the failure to observe horseradish peroxidase‐II in the steady state of the reaction. In the spectral range investigated (390–700 nm) the observed emission (570–700 nm) is ascribed to the biradical, as the latter is equivalent to an excited state of the postulated iminium cation.While lipoxygenase has no effect upon JV‐methylcarbazole, it markedly enhances the emission if peroxidase is present. This effect requires oxygen and is ascribed to an excited product formed by lipoxygenase acting upon an intermediate hydroperoxide of the aerobic process promoted by

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1994.tb08237.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY