EFFECTS OF ULTRAVIOLET RADIATION ON THE MITOTIC CYCLE AND DNA, RNA AND PROTEIN SYNTHESIS IN MAMMALIAN EPIDERMIS IN VIVO

Abstract— Acute effects of ultraviolet radiation on the mitotic cycle and macromolecular synthesis were investigated on hairless mouse epidermis in vivo. Colcemid was used to arrest mitoses in metaphase and thus allow more accurate mitotic counts. The radioactive tracers, TdR-³H, cytidine-³H, and the amino acids, histidine-³H and methionine-³H were used to examine DNA, RNA and protein synthesis, respectively. Using these techniques, we found that wavelengths shorter than 320 nm markedly inhibited mitosis, increased the basal cell turnover time and depressed DNA, RNA and protein synthesis within the first few hours post-irradiation. By 24hr, recovery and acceleration of these functions were in progress, reaching a peak by 48–72 hr and persisting though to a lesser degree for 7 days. This stage of acceleration was associated with epidermal hyperplasia and most likely represented post-injury cell renewal.     

IN VITRO AND IN VIVO PROTECTION AGAINST PHOTOTOXIC SIDE EFFECTS OF PHOTODYNAMIC THERAPY BY RADIOPROTECTIVE AGENTSWR–2721 ANDWR–77913

Abstract— The experimental radioprotective agentsS–2-(3-aminopropylamino) ethyl phosphorothioate(WR–2721) and 3-amino-2-hydroxypropyl phosphorothioate(WR–77913) are also protective against photosensitized oxidation. They reduce porphyrin-induced photopolymerization of lens cytosol proteins in vitro, and phototoxic damage to mouse skin in vivo. The phototoxic dose modification factor (DMF) was 1.5 which is similar to that found in ionizing radiation. Part of the mechanism by which sulfhydryls afford this protection is by accelerating photobleaching of the porphyrins.     

FORMATION OF THYMINE DIMERS IN MAMMALIAN SKIN BY ULTRAVIOLET RADIATION IN VIVO

Abstract— Ultraviolet radiation of 220–300 nm is known to produce cyclobutyl pyrimidine dimers in extracellular DNA, in bacteria, and in mammalian cells in culture. The formation in vivo of such dimers in mammalian skin has remained inferential. We report that one of the important and recognizable biologic events that occurs in mammalian skin during irradiation is the formation of thymine dimers. [³H]-labelled thymidine was applied to the epilated skin of guinea pigs to label their DNA. Animals were irradiated individually, using wavelengths of either 254, 285–350, or 320–400 nm. Immediately after irradiation, epidermis was separated from the rest of the skin and homogenized; DNA and RNA were isolated. Irradiation with wavelengths of 285–350 nm, which included the sunburn-producing spectrum (i.e., 290–320 nm), produced thymine dimers (1·7–2·6 per cent of the total [³H]-thymine incorporated into DNA). Irradiation with 254nm also produced fewer dimers (0·46–1·2 percent); and 320–400 nm produced none. The dimer could be cleaved by 250 nm radiation to form thymine. The epidermal cell damage by ultraviolet radiation, particularly by the sunburn-producing spectrum (290–320 nm), may be related to the formation of such dimers.     

PHOTOSENSITIZING EFFECTS OF 8-METHOXYPSORALEN ON THE SKIN OF HAIRLESS MICE—I. FORMATION OF INTERSTRAND CROSS-LINKS IN EPIDERMAL DNA

Abstract— The photomediated induction of interstrand cross-links by 8-methoxypsoralen has been measured in the epidermal DNA of hairless mice. Equivalent efficiencies for cross-link induction were determined for HRS/J/Anl and SKH: hairless-1 mice. A wavelength dependence on the relative efficiency of cross-link induction was observed; a broad spectrum light source, 300–400 nm, was approximately 5 times more effective in cross-link formation than a 365 nm light source. Repeated exposure to 8-methoxypsoralen followed by ultraviolet light, 5 times a week for 6 weeks, altered epidermal thickness and resulted in a decreased efficiency for DNA cross-link formation.     

IN VIVO and POST MORTEM MEASUREMENTS OF THE ATTENUATION SPECTRA OF LIGHT IN MAMMALIAN TISSUES

Abstract— The attenuation of light in rabbit liver and striated muscle and in pig brain has been measured in the wavelength range400–800 nrn. A variable-wavelength monochromatic light source was used to illuminate the surface of the exposed tissues in situ. Optical fibers, coupled to a single photon counter, were positioned within the tissues at different depths to determine the distribution of light flux along the central axis of the light beam. The wavelength-dependence of attenuation was measured in vivo, and changes occurring in the attenuation spectra immediately post mortem were recorded. Strong absorption bands were observed around 425 nm and 550 nm in all three tissues, both in vivo and post mortem. At longer wavelengths, the attenuation decreased slowly, and no significant structure was observed. Substantial changes occurred immediately post mortem, particularly in the absorption bands. These effects are attributed mainly to de-oxygenation of blood, and changes in blood concentration in the tissues. The implications for light dosimetry in photodynamic therapy are discussed.     

PHOTOTOXIC EFFECTS OF NATURALLY OCCURRING POLYACETYLENES AND α-TERTHIENYL ON HUMAN ERYTHROCYTES

Hemolysis, K⁺ leakage and acetylcholinesterase (AChE) inhibition in human erythrocytes were observed with certain naturally occurring polyacetylenes and a thiophene derivative, α-terthienyl. K' leakage, subsequent hemolysis and AChE inactivation by phenylheptatriyne (PHT), a phototoxic compound, were considerably enhanced by UV light (312–400 nm). The same was true with α-terthienyl and with certain other polyacetylenes. Oxygen enhanced AChE inactivation and hemolysis with α-terthienyl in light. With PHT, only AChE inhibition was significantly enhanced in oxygen. Falcarindiol, a non-phototoxic polyacetylene, did not inactivate this enzyme but caused hemolysis in the dark. Inhibition of AChE and hemolysis by these compounds appear to be unrelated phenomena. These results indicate that certain polyacetylenes are capable of damaging biological membranes in light, and others in dark.     

THE EFFECT OF CHRONIC APPLICATIONS OF TRETINOIN(RETINOIC ACID) ON ACUTE RESPONSES OF MAMMALIAN SKIN TO UVB RADIATION IN VIVO

Abstract The effects of long—term applications of tretinoin(retinoic acid; RA) on acute responses to UVB radiation were examined in hairless mouse skin in vivo. The skin was examined histologically and the radioactive tracer [³H]-thymidine was used to study premitotic semiconservative DNA synthesis in the epidermal basal cells. Ten and 23 wk applications of a 0.05% RA solution (3 times a wk) induced epidermal acanthosis, hypertrophy of the individual cells and an increased number of [³H]-thymidine-labelled basal cells. At both time periods there was a distinct reduction in the expected inhibition of DNA synthesis at 4 h and the expected acceleration of DNA synthesis at 48 h after a single exposure to UVB radiation. In addition, the histologic morphology was unchanged at 48 h post irradiation. Thus, the repeated RA applications had a definitive influence on at least two aspects of the cutaneous response to UVB energy.     

EFFECTS OF ACRIDINE PLUS NEAR ULTRAVIOLET LIGHT ON ESCHERICHIA COLI MEMBRANES AND DNA IN VIVO

Results from a variety of experiments indicate that photodynamic damage to E. coli treated with the hydrophobic photosensitizer acridine plus near-UV light involves both cell membranes and DNA. Split-dose survival experiments with various E. coli mutants reveal that cells defective in rec A, uvr A, or pol A functions are all capable of recovery from photodynamic damage. Alkaline sucrose gradient analysis of DNA from control and treated cells revealed that acridine plus near-UV light treatment converts normal DNA into a more slowly sedimenting form. However, the normal DNA sedimentation properties are not restored under conditions where split-dose recovery is effective. Several lines of evidence suggest that membrane damage may be important in the inactivation of cells by acridine plus near-UV light. These include (a) a strong dependence of sensitivity on the fatty acid composition of the membranes; (b) a strong dependence of sensitivity on the osmolarity of the external medium; and (c) the extreme sensitivity of an E. coli mutant having a defect in its outer membrane barrier properties. Direct evidence that acridine plus near-UV light damages cell membranes was provided by the observations that (a) the plasma membrane becomes permeable to o-nitrophenyl-ß-D-galactopyranoside and (b) the outer membrane becomes permeable to lysozyme after treatment. A notable result was that cells previously sensitized to lysozyme by exposure to acridine plus near-UV light lose that sensitivity upon subsequent incubation. This strongly suggests that E. coli cells are capable of repairing damage localized in the outer membrane.     

铁、钠杂质对甲硫醚合成中γ-Al2O3催化行为的影响

系统地研究了γ－Al2O3催化剂中杂质Fe和Na对甲硫醚合成的催化行为的影响。随着Fe含量的增大，甲醇分解反应加剧，硫醇产率增高，甲硫醚产率下降；Na含量越低，甲醇分解率越高。Na含量在0．2％－0．4％时，甲硫醚产率最高，甲硫醇生成率最高；Na含量进一步增大时，甲醇双分子脱水生成甲硫醚的量增加，甲硫醇产率增高，生成甲硫醚的选择性下降。     

不同有机胺对合成杂原子Ga－Si－ZSM－5分子筛的影响

考察了几种有机胺作引导剂对以水玻璃为硅源、硝酸镓为镓源合成Ｇａ－Ｓｉ－ＺＳＭ－５分子筛的影响。结果表明，合成体系的最佳碱度与有机胺有关，不同有机胺的合成效果相差很大，以正丁胺作引导剂可获得高结晶度的分子筛产物。通过与合成Ａｌ－Ｓｉ－ＺＳＭ－５的比较和一些条件试验，探讨了有机胺的作用，并对分子筛的形成过程进行了合理的推测。     

UV-ENHANCED VIRUS REACTIVATION IN MAMMALIAN CELLS: EFFECTS OF METABOLIC INHIBITORS*

Abstract—The induction process of UV-enhanced reactivation of UV-irradiated herpes simplex virus was investigated in CV-1 monkey kidney cells. A protein synthesis inhibitor, cycloheximide (0.5–5 μg/m/), present in the culture medium For 24 h between cell irradiation and virus infection decreased the enhanced virus survival normally found in UV-irradiated cultures. The enhanced virus reactivation became essentially resistant to the addition of cycloheximide by 6–8 h after cell irradiation, indicating that the cycloheximide-sensitive process necessary for enhanced reactivation was complete by that time. Since cycloheximide not only inhibits protein synthesis, but DNA synthesis as well, we investigated the effect of a DNA synthesis inhibitor, hydroxyurea. Hydroxyurea did not decrease UV-enhanced virus survival, but resulted in enhanced virus survival even in unirradiated cells. Therefore, the cycloheximide-caused inhibition of UV-enhanced reactivation did not arise from inhibition of DNA synthesis. The combined results indicate that (1) UV-enhanced virus reactivation in monkey kidney cells requires de novo protein synthesis during the first 6–8 h after cell irradiation and that (2) DNA synthesis inhibition may be the initiating event.     

PHOTOTOXIC EFFECTS OF FOUR PSORALENS ON L1210 CELLS. THE CORRELATION WITH DNA INTERSTRAND CROSS-LINKING

L1210 mouse leukaemia cells were treated with psoralen [S-methoxy-(XMOP), 4,5′,8-trimethyI-(TMP), 4′-hydroxymethyl-4,5′,8-trimethyl-(HMT) or 4′-amino- methyl-4,5′,8-trimethylpsoralen (AMT)] in combination with long wavelength ultraviolct irradiation (Λ～ 365 nm). In order to investigate the relative photobiological activities of the psoralens, cell viability and DNA-synthesis activity as well as psoralen-DNA photoaddition and DNA interstrand cross-linking were measured after the treatment. In all assays the activity ranking order was found to he: TMP > HMT > AM7 > 8MOP. Furthermore, a direct correlation between phototoxicity, psoralen induced DNA interstrand cross-links and inhibition of DNA synthesis was indicated. Finally, psoralen uptake by the cells appears to be an important determinant for phototoxicity, whereas their DNA photoreactivity does not.     

EFFECTS OF SYNTHESIS PARAMETERS ON ZEOLITE ZSM-48 IN A SOLID REACTION MIXTURE SYSTEM

IntroduCtionReCently,zcoliteZSM-48hasbeenspehesizedinapurelysolidsystemll1.Thismethedusedtosynthesizezcolitescangndlyincreasetheyieldofpnductsperunitvolume,simplifythepr0cedresanddecreasethecnvironmentalpolluti0n.ThisincreasestheacualPOssibilityofsynthesisofhigh-silicazcolitesinchemicalindustry.MoreOver,itisalsohelpfulforstUdyingthezeolitecrystalliZai0nmechanism.ItiswellknownthatthesamewneofzeolitessynthesizedindifferentsystemshasdifferentcatalyticpropertiesduetothechangesoftheirfinestruC…     

EFFECT OF CHRONIC UV EXPOSURE ON EPIDERMAL TRANSMISSION IN MICE*

In connection with an investigation on UV-tumorigenesis in hairless mice, the question arose in what way the epidermal transmission changes under chronic UV exposure. At regular time intervals, epidermal sheets of these mice were optically probed, i.e. the specimen was irradiated perpendicularly to its surface with a collimated monochromatic beam of 313, 302 or 297 nm and the transmission was measured in forward direction and a small angle around it. The optical probe measurement was sensitive to epidermal changes and easy to perform; it correlated well with thickness and total transmission of the epidermal sheet. As a result it was found that over the dose range investigated the logarithm of the epidermal transmission at 297 nm was a simple linear function of the daily UV dose and the time of treatment. Calculations, in which this result is combined with data on UV-tumorigenesis over the same dose range, show that the change in epidermal transmission is sufficiently large to have an important bearing on the dose-response relationship for tumorigenesis by chronic UV exposure.     

模板剂对ZSM—35沸石合成及其物化性能的影响

本文分析了乙二胺和正丁胺为模板剂，在水热体系Ｎａ２Ｏ－ＳｉＯ２－Ａｌ２Ｏ３－Ｈ２Ｏ中合成了ＺＳＭ－３５沸石，并利用ＸＲＤ，ＳＥＭ，ＩＲ及ＣＯ加氢反应手段考察了其物理化学特性。结果表明，模板剂对ＺＳＭ－３５沸石的合成，结构，形貌，红外振动，稳定性及催化性能有显著的影响作用。     

β—（酚酯基）乙基锗倍半氧化物的合成及对体外培养细胞的作用

β-羧基乙基锗倍半氧化物(即Ge-132)是一种无毒和具较强抗癌活性的有机锗化合物。为了进一步提高其抗癌活性。已对Ge-132进行了化学结构修饰。本文介绍8种未见报导的Ge-132衍生物,β-酚酯基乙基锗倍半氧化物的合成和体外培养细胞实验结果。     

MUTAGENIC EFFECTS PHOTOINDUCED IN MAMMALIAN CELLS IN VITRO BY TWO MONOFUNCTIONAL PYRIDOPSORALENS

Abstract— The photobiological activity of the two monofunctional pyridopsoralens pyrido (3,4-c) psoralen (PyPs) and 7-methyl pyrido (3,4-c) psoralen (MePyPs) was studied in mammalian cells in vitro taking 8-methoxypsoralen (8-MOP) as a reference compound.
In the presence of 365-nm irradiation (UVA) MePyPs was found to be more effective than 8-MOP in terms of DNA photobinding capacity and inhibition of cell cloning ability in Chinese hamsterV–79 cells. As a function of UVA dose and of the number of total photoadducts induced MePyPs produced a higher frequency of 6-thioguanine resistant mutants than 8-MOP. PyPs showed an intermediate response for cell killing and mutation induction. At equal cytotoxic levels both monofunctional pyridopsoralens exhibited the same mutagenic activity as the Afunctional furocoumarin 8-MOP.
The antiproliferative effect being taken as indicative for an efficient photochemotherapeutic activity against psoriasis, the inhibition of cloning capacity induced by MePyPs plus UVA was studied in parallel on human skin fibroblasts. Such cells were more sensitive to 8-MOP photoadditions thanV–79 cells and even more so to MePyPs photoadditions. Data obtained on the rate of DNA semi conservative synthesis on both cell lines following treatments with the two compounds are in line with these observations.     

SUBSTITUENT DIRECTIVE EFFECTS IN THE FRIEDEL-CRAFTS SYNTHESIS OF SUBSTITUTED PHENOXAPHOSPHINIC ACIDS

Abstract

Although meta-substituents on diphenyl ethers block attack at the para-position in the reaction with phosphorus trichloride and aluminium chloride, in some cases phosphorylation occurs in the even sterically more shielded ortho-position, leading to mixtures of isomeric phenoxaphosphinic acids. This effect and the obtained ratios of isomers can be explained by different substituent directive effects in a two step reaction mechanism.