INHIBITION OF PHTHALOCYANINE-SENSITIZED PHOTOHEMOLYSIS OF HUMAN ERYTHROCYTES BY QUERCETIN

Abstract— Photohemolysis of erythrocytes in the presence of aluminum phthalocyanine tetrasulfonate as a sensitizer is inhibited by quercetin. D₂O (98.5%) stimulated photohemolysis regardless of quercetin presence, suggesting the participation of singlet oxygen in the process. Since it has been shown that this flavonoid reacts with singlet oxygen, the protective effect might be attributed, at least partially, to its competitive reaction with singlet oxygen. At the molecular level, the alterations of membrane proteins that escort the process of photohemolysis, such as cross-linking of spectrin monomers and of other membrane proteins, were selectively inhibited by quercetin. This effect was qualitatively similar to that induced by NaF, suggesting that quercetin may, like NaF, also inhibit type I photooxidations, which contribute to hemolysis. The lipophilicity of quercetin seems to be an essential factor in the inhibition process; rutin, a water-soluble 3-rutinoside of quercetin, had only a negligible protective effect on photohemolysis.     

PHOTOHEMOLYSIS OF HUMAN ERYTHROCYTES LABELED IN BAND 3 WITH EOSIN-ISOTHIOCYANATE

Eosin-isothiocyanate (EYNCS) is 50 to 100 times more effective in sensitizing delayed photo-hemolysis of human erythrocytes than is eosin when matched for absorbance in the reaction medium. These dyes are equally efficient in generating singlet oxygen, a potent membrane oxidant. When cells are treated with sensitizer and washed extensively prior to illumination, EYNCS phototoxicity persists, while that of eosin is lost. SDS-gel electrophoresis of membranes from EYNCS-exposed cells shows a large fluorescence signal coincident with band 3 protein that is abolished by pretreatment with H₂DIDS, the inhibitor of anion exchange by band 3. This treatment reduces the photohemolytic potency of EYNCS by over 90%. The marked enhancement of photohemolytic activity upon binding sensitizer to band 3 implicates band 3 itself as a site of photodamage leading to lysis.     

MECHANISM OF PHOTOSENSITIZATION BY PHEOPHORBIDE a STUDIED BY PHOTOHEMOLYSIS OF ERYTHROCYTES AND ELECTRON spIN RESONANCE SPECTROSCOPY

Abstract Phcophorbide a (PPa), a causal substance of food intoxication, when excited by exposure to light wavelengths of over 600 nm, caused the photohemolysis of goat erythrocytes in proportion to the incubation time of the cells. The addition of N-₃, an effective scavenger of ¹O₂, to the medium markedly inhibited the hemolysis of erythrocytes in a concentration-dependent manner, whereas the addition of superoxide dismutase (SOD) and catalase, inhibitors of O^-₂ and H₂O₂ generation, respectively, to the medium had little effect on it.
Methods for converting ¹O₂ to a nitroxide radical by 2,2,6,6-tetramethyl-4-piperidone (TMPD) and for trapping O^-₂ and OH by 5,5-dimethyl-l-pyrroline-A'-oxide (DMPO) were employed to observe directly these activated oxygens by electron spin resonance (ESR). The methods provided evidence that only ¹O₂, was produced by PPa, which was excited by light wavelengths of over 600 nm. Both the addition of N₃ to the solution and the removal of oxygen from the solution inhibited the generation of ¹O₂.
These results led us to conclude that ¹O₂ was mainly responsible for the hemolysis of erythrocytes by photoexcited PPa.     

磁场对乙基纤维素胆甾型液晶相的影响

高分子胆甾型液晶相是一个在高分子和液晶领域都引起广泛兴趣的课题,不仅因为自然界中的多种生物大分子,如纤维素,多肽,DNA等可以形成胆甾型液晶相;而且由于胆甾相具有特殊的螺旋结构(如图1所示),能产生一些特殊的光学性能,如强烈的旋光性,圆二色性和选择性反射光性能等;并带来相应的应用,正是由于高分子胆甾相材料的性能和应用,使得高分子胆甾相液晶的相态转变和结构变化也一直倍受关注。     

磁场对微乳液法合成聚苯胺结构及其电化学行为的影响

在不同磁场强度下,采用微乳液聚合法合成导电聚苯胺(PANI),以碳纸负载PANI为工作电极,通过循环伏安测试方法,探讨了磁场、氧化剂浓度和聚合时间对微乳液聚合法合成PANI电化学性能的影响;并通过X射线衍射(XRD)、四探针电导率测试和傅立叶红外光谱(FTIR)对产物结构和性能的表征分析,印证了循环伏安分析结果的可靠性.实验结果表明,与无磁条件下制备的PANI相比,磁场条件下制备的PANI具有较高的导电性和规整度;FTIR谱图分析表明,由于磁场的取向作用使分子间相互作用力降低,分子链离域程度增大,使磁场条件下合成PANI的主要特征峰有向低频方向移动的趋势,但分子的基本结构单元没有发生变化.研究结果显示,利用负载PANI的碳纸为工作电极,能够对微乳液法合成PANI的电化学行为进行有效的实时表征.     

SUBCELLULAR LOCALIZATION OF AND PHOTOSENSITIZATION BY PROTOPORPHYRIN IX IN HUMAN KERATINOCYTES AND FIBROBLASTS CULTIVATED WITH 5-AMINOLEVULINIC ACID

Abstract— The subcellular localization of protoporphyrin (PP) has been studied by microspectrofluo-rometric techniques in NCTC 2544 keratinocytes incubated with 5-aminolevulinic acid (ALA) for times up to 42 h. Whereas the plasma membrane shows strong staining, fluorescent spots are observed within the cytoplasm especially in the perinuclear region. Although the topographic pattern of the PP distribution does not change much with the incubation time with ALA, the fluorescence spectra suggest that the PP microenvironments are quite different at short and long incubation times. Addition of 18 uJW desferoxamine almost doubles the ALA-induced PP concentration. Colocalization experiments with rhodamine 123, a mitochondrial probe, and lucifer yellow (LY) or neutral red (NR), two lysosome probes, demonstrate that at least some of these spots are of lysosomal origin. Study of the time evolution of the NR fluorescence under irradiation with visible light in the presence and absence of ALA demonstrates that lysosomes are damaged in cells that have synthesized PP. No PP fluorescence can be detected in mitochondria after incubation with ALA. However, photosensitization of mitochondria occurs under irradiation with visible light. Very little formation of lipofuscins by photosensitization with exogenous PP or ALA-induced PP is observed with the NCTC 2544 keratinocytes, as compared to normal human fibroblasts.     

PAMAM树状大分子对酮基布洛芬溶解度的影响

以酮洛芬为模型药物,研究聚酰胺-胺(PAMAM)树状大分子对酮洛芬的增溶作用,并探讨其作用机理.采用紫外光谱法测定了G1.0、G1.5、G2.0、G2.5、G3.0、G3.5PAMAM在不同浓度和不同pH时对酮洛芬的增溶量.并运用计算机模拟方法对PAMAM与酮洛芬相互作用的机理进行了探讨.实验结果表明,酮洛芬的溶解度随溶液pH值变化而变化,在pH4.0～6.0范围内,PAMAM树状大分子对酮洛芬的增溶量随着PAMAM的代数、浓度和溶液pH的增加而增大.整代和半代都具有增溶作用.然而,在同一pH条件下,对于具有相同官能团数目的整代和半代,整代增溶效果要高于半代.计算机模拟结果表明PAMAM与酮洛芬主要靠静电作用力结合.增溶机理可能是酮洛芬的羧基与PAMAM的伯胺和叔胺发生静电作用.     

磁场对聚乙烯基萘敏化AIBN引发苯乙烯本体光聚合反应的影响

<正> 近年来,Turro等人发现,外磁场能提高一些由油溶性酮类化合物(如二苄基酮)为引发剂的乳液聚合体系的分子量,并且显著地影响所生成聚合物的立体构型,因而引起了人们的注意。     

MOLECULAR MECHANISM OF DRUG PHOTOSENSITIZATION–II. PHOTOHEMOLYSIS SENSITIZED BY KETOPROFEN

Red blood cell lysis photosensitized by ketoprofen (KPF) was investigated. The photohemolysis was inhibited by butylated hydroxyanisole, reduced glutathione, superoxide dismutase and mannitol, and was unaffected by sodium azide; the presence of oxygen markedly enhanced the lysis. Photohemolysis was also observed under anaerobic conditions. Ketoprofen, irradiated in aqueous buffer solution at pH 7.4, underwent a decarboxylation process via intermediate radicals, leading to the compounds (3-benzoylphenyl)ethane, (3-benzoylphenyl)ethyl hydroperoxide, (3-benzoylphenyl)ethanol and (3-benzoylphenyl)ethanone under aerobic conditions and only to the compound (3-benzoylphenyl)ethane under anaerobic conditions. The four photoproducts showed lytic activity, particularly high for the alcohol and hydroperoxide. The overall results suggest for KPF-photosensitized hemolysis a molecular mechanism involving free radicals, superoxide anion and sensitizer photodegradation products.     

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.     

PHOTOOXIDATION AND SINGLET OXYGEN SENSITIZATION BY PROTOPORPHYRIN IX AND ITS PHOTOOXIDATION PRODUCTS

Protoporphyrin IX and its various ester derivatives have been previously shown to undergo self-sensitized photooxygenation to yield hydroxyaldehydes (photoprotoporphyrin) and mono- and diformyl deuteroporphyrin derivatives. In the present study the photoreactions of these products in the presence of oxygen have been investigated. All of the photooxidation products are themselves good sensitizers of singlet oxygen. In addition spin trapping experiments indicate these products can produce superoxide in low-to-moderate efficiency by an excited state electron transfer process. The photo-products themselves are somewhat more stable to photooxidation than protoporphyrin IX itself. The two monoformyl-monovinyl deuteroporphyrins have been found to undergo further photooxidation at the vinyl groups to yield primarily monoformyl hydroxyaldehydes in a reaction mainly involving singlet oxygen analogous to the initial reaction of protoporphyrin IX.     

HEMOLYSIS OF HUMAN ERYTHROCYTES BY ACTIVATED OXYGEN SPECIES

Abstract— The hemolysis of human erythrocytes by irradiation at 254 nm has been studied. Neither superoxide radicals nor singlet oxygen play a significant rôle and it is likely that the major species involved are hydroxyl radicals and, indirectly, carbonate anion or formate radicals. Similarly, when erythrocytes are treated with a system commonly used as source of superoxide radicals (photoreduction of riboflavin) it has been demonstrated that O^-₂ does not participate in lysis, but that singlet oxygen (possibly with hydroxyl radicals) is a major oxygen species involved in destruction of the cell membrane.     

THE PHOTOTOXIC EFFECT OF BENOXAPROFEN AND ITS ANALOGS ON HUMAN ERYTHROCYTES AND RAT PERITONEAL MAST CELLS

Abstract— Benoxaprofen [2-(4-chlorophenyl)-α-methyl-5-benzoxazoleacetic acid] is a phototoxic non-steroidal anti-inflammatory agent. Irradiation of human erythrocytes in the presence of benoxaprofen (8 μ M ) and oxygen resulted in rapid cell lysis which began after 10 min and was complete within 30 min. While photohemolysis was also observed under anerobic conditions, its onset was delayed for more than 20 min and it took nearly 100 min for complete lysis to occur. Photohemolysis was also delayed by butylated hydroxyanisole but was unaffected by reduced glutathione. 1,4-diazabicyclo[2.2.2]octane, D₂O. β-carotene, or superoxide dismutase. The main photoproduct of benoxaprofen, 2-(4-chlorophenyl)-5-ethylbenzoxazole, was almost as effective in causing photohemolysis as benoxaprofen itself. In the presence of UV irradiation, benoxaprofen (10 (μ M ) caused the degranulation of rat peritoneal mast cells and the release of histamine. The release of mast cell histamine may provide a reasonable explanation for the urticarial response to benoxaprofen and irradiation seen in human subjects.     

趋磁性细菌-磁场处理含镍废水的研究

应用趋磁性细菌-磁场技术处理Ni2 废水.首先进行了趋磁性细菌吸附试验,研究了pH、温度、时间、微生物量对吸附的影响.其次进行了趋磁性细菌的分离试验,考查了磁分离器中金属丝框的位置和磁场强度对磁分离过程的影响.试验结果表明,经这种方法处理后,出水中镍离子浓度很低.     

吐温-80对固定化脂肪酶催化酮基布洛芬氯乙酯对映体选择性水解反应的影响

酮基布洛芬为2-芳基丙酸类非甾体抗炎药的一种,其药效与立体构型有很大关系[1].生物法催化的动力学拆分是获得单一对映体酮基布洛芬的有效方法之一[2,3].最近,我们发现在利用皱褶假丝酵母(Candida rugosa)脂肪酶Lipase OF催化拆分酮基布洛芬氯乙酯时,向反应体系中加入非离子表面活性剂吐温-80,不仅可大幅度提高反应速度,而且更重要的是解决了原来Lipase OF选择性较差的问题,从而为酮基布洛芬的对映体拆分提供了一种新方法.     

THE EFFECTS OF PHOTOACTIVATED PROTOPORPHYRIN ON RETICULOCYTE MEMBRANES, INTRACELLULAR ACTIVITIES and HEMOGLOBIN PRECIPITATION

Abstract— Photoactivated protoporphyrin effects were studied on reticulocyte membranes and distinct intracellular activities. Membrane bound (Na ₊ -K ₊)-ATPase activity and incorporation of ₅₅Fe into heme were almost 80% inhibited at a low concentration of protoporphyrin (3 fiM). On the other hand, a much higher protoporphyrin concentration (15 nM) was needed to cause 80% inhibition of protein synthesis. By 15 JXM protoporphyrin and treatment with light, an initial leak of hemoglobin out of the cells was observed. Electron microscopic examination showed that the lytic effects seem to be a result of membrane damage which appeared as holes in the membrane. Heinz-body-like particles of condensed hemoglobin were observed in the protoporphyrin-treated cells. The condensed hemoglobin spheres were shown to be bound to disrupted membranes prepared from photoactivated protoporphyrin-treated reticulocytes     

THE EFEFCT OF MAGNETIC FIELD ON POLYMERIZATION OF STYRENE IN THE PRESENCE OF POLYVINYL NAPHTHALENE AND POLYVINYL BENZOPHENONE

In the process of bulk photopolymerization of styrene initiated by AIBN decomposition polyvinyl benzophenone (PVB) can supply an effective cage for triplet-triplet energy transfer between PVB macromolecules and small molecules of AIBN to influence the molecular weight of polystyrene in weak magnetic field (less than 0.035T), that was different from the case of polyvinyl naphthalene (PVN) which supplied cages for this system only in the stronger magnetic field (more than 0.2 T) studies. It was found that in the same conditions, PVN could exert more tremendous influences on the bulk photopolymerizatiou system of styrene than PVB because in the stronger magnetic field the triplet PVN had much longer life time than PVB.     

THE PHOTOTOXICITY OF PHENYLHEPTATRIYNE: OXYGEN-DEPENDENT HEMOLYSIS OF HUMAN ERYTHROCYTES AND INACTIVATION OF Escherichia coli

Abstract— Phenylheptatriyne (PHT) plus near-ultraviolet light(320–400 nm; NUV) hemolyzed human erythrocytes in an oxygen dependent manner. When the phototoxicity of PHT plus NUV was tested with a series of Escherichia coli strains carrying all four possible combinations of genes controlling excision proficiency ( uvrA6 vs uvrA ⁺) and catalase activity (HPII, katF vs katF *), the membrane was found to be an important lethal target. Consistent with this observation. PHT plus NUV did not induce histidine independent ( his-4 ⁺) mutations in the four tester strains (RT7h-RT10h). Using tester strain RT10h, it was shown that there was no inactivation by PHT plus NUV in nitrogen. Results of experiments with an E. coli fatty acid auxotroph (K1060) treated with PHT plus NUV are also consistent with membrane proteins being the chief targets for attack. Radicals were formed during the photolysis of PHT plus NUV in aqueous solutions, both in the presence of air and under nitrogen. Since PHT plus NUV did not hemolyze erythrocytes or inactivate E. coli cells under nitrogen, these radicals are not cytotoxic.     

THE EFFECTS OF MAGNETIC FIELD ON GRAFT COPOLYMERIZATION OF METHYL METHACRYLATE ONTO POLYVINYL ALCOHOL IN THE PRESENCE OF BENZOPHENONE DURING UV IRRADIATION

The effects of magnetic field on the graft ratio and stereoregularity of grafts of PVA-g-MMA in the presence ofbenzophenone during UV irradiation are discussed. By means of IR, it was found that the graft ratio was increased with the increment of magnetic field strength. Furthermore, application of relative weak magnetic field of 0.4 Tesla had been shown to substantially enhance the stereo-regularity of graft copolymer. The maximum stereo-regularity appeared when the graft ratio approached to 85% with the magnetic field of 1.2 Tesla (T). The resistance to moisture and heat resistance of the grafted copolymer in the presence of magnetic field were also improved.     

PHOTODESTRUCTION OF TUMOR CELLS BY INDUCTION OF ENDOGENOUS ACCUMULATION OF PROTOPORPHYRIN IX: ENHANCEMENT BY 1, 10-PHENANTHROLINE

Rapidly proliferating transformed mammalian cells can be photodestroyed in vitro upon inducing the accumulation of endogenous protoporphyrin IX (Proto). Proto biosynthesis and accumulation were triggered by manipulation of the porphyrin-heme biosynthetic pathway. Proto accumulation in cultured cells was induced by treatment with 1.0 mM delta-aminolevulinic acid (ALA), a naturally occurring 5-carbon amino acid, for 3.5 h. In darkness, significant Proto accumulation became evident within 3.5 h of incubation. In the light, the accumulated tetrapyrroles triggered destruction of treated cells within the first 30 min of illumination, probably via the rapid oxidation of cellular constituents by singlet oxygen. Protoporphyrin IX accumulation and specific cell lysis increased significantly by inclusion of 0.75 mM 1,10-phenanthroline (Oph), a tetrapyrrole biosynthesis modulator. Slower growing untransformed cells did not accumulate significant amounts of Proto following ALA and Oph treatment unless stimulated to proliferate with the mitogenic lectin Concanavalin A.