Antioxidant activity of a botanical extract preparation of Ilex paraguariensis: prevention of DNA double-strand breaks in Saccharomyces cerevisiae and human low-density lipoprotein oxidation

We analyzed the antioxidant properties of Ilex paraguariensis infusion (Ip) popularly known as mate (m?'tā), by using two experimental models: the induction of DNA double-strand breaks (DSB) by hydrogen peroxide (H(2)O(2)) and lethality in Saccharomyces cerevisiae, as well as peroxide and lipoxygenase-induced human low-density lipoprotein (LDL) oxidation. Diploid yeast cells were exposed to different concentrations of H(2)O(2) (5-10 mmol/L) in the absence or presence of Ip infusion (10(-1) v/v) or alpha-tocopherol (10(-2) mol/L). Both mate infusion and alpha-tocopherol significantly decreased the dose dependent DSB number, and the lethality induced by H(2)O(2). Peroxynitrite and lipoxygenase-induced human LDL oxidation are inhibited by Ip extracts in a potent, dose-dependent fashion. Dilutions of 5 x 10(-3) v/v provide 50% +/- 10% inhibition. Finally, Ip extracts are potent direct quenchers of the free radical 1,1-diphenyl-2-picrylhydrazyl. Dilutions of 2 x 10(-2) v/v produced quenching of more than 30%, which was comparable to that obtained with 0.5-1 mmol/L alpha-tocopherol or the quercetin aglycone, respectively. For comparison, total polyphenol content of Ip, green, and black tea (Camelia sinensis) were 6.5 +/- 0.8; 1.8 +/- 0.5; and 1.13 +/- 0.3 mmol of quercetin equivalents per liter, respectively. Their respective free radical quenching activities at dilutions of 1 x 10(-1) v/v were 75% +/- 5%; 35% +/- 5%; and 2% +/- 5%. Ip is thus a rich source of polyphenols and has antioxidant properties comparable to those of green tea which merit further in vivo intervention and cross-sectional studies.     

The ECG-phenomenon of ST segment elevation: the reasons for it and its clinical significance

The authors adduce a detailed analysis of the reasons for ST segment elevation, which is found in patients with various pathologic conditions and in some normal individuals, basing this analysis on their own experience and literature data. The authors pay special attention to differential ECG-diagnostics of ST elevation, which plays the most significant part in practice.     

IgG与血清裂解质粒DNA能力的相关性

目的　探讨IgG与血清裂解质粒DNA的效应成分的关系及IgG裂解能力与多种抗核抗体的关系。 方法　用DEAE纤维素自血清提纯IgG并收集去IgG组分 ,琼脂糖凝胶电泳观察与质粒 pUC19作用后的产物 ,间接免疫荧光法及免疫印迹法测定ANA ,抗ds DNA、抗ENA。结果　IgG的裂解能力与血清裂解能力密切相关 ,而去IgG组分裂解能力与血清裂解能力无关 ;SLE组和免疫相关疾病组IgG与血清的裂解能力与正常对照组相比有显著差异 ,疾病组间无显著差异 ;IgG的裂解能力分别与ANA、抗ENA、抗ds DNA相关 ;裂解后 ,pUC19在电泳图谱上表现为 2～ 4个小于阴性对照的片段 ;同一样本血清及IgG作用后得到数目相等、分子大小相似的片段。结论　IgG与血清的裂解活性密切相关 ,IgG可能为血清裂解质粒DNA活性的效应成分     

Drug features that contribute to the activity of quinolones against mammalian topoisomerase II and cultured cells: correlation between enhancement of enzyme-mediated DNA cleavage in vitro and cytotoxic potential.

CP-115,953 [6,8-difluoro-7-(4'-hydroxyphenyl)-1-cyclopropyl-4- quinolone-3-carboxylic acid] is a novel quinolone that is highly active against topoisomerase II in vitro and in mammalian cells in culture (M. J. Robinson, B. A. Martin, T. D. Gootz, P. R. McGuirk, M. Moynihan, J. A. Sutcliffe, and N. Osheroff, J. Biol. Chem. 266:14585-14592, 1991). However, the features of the drug that contribute to its activity towards mammalian systems have not been characterized. Therefore, CP-115,953 and a series of related quinolones were examined for their activity against calf thymus topoisomerase II and cultured mammalian cells. CP-115,953 stimulated DNA cleavage mediated by the type II enzyme with a potency that was approximately 600-fold greater than that of the antimicrobial quinolone ciprofloxacin and approximately 50-fold greater than that of the antineoplastic drug etoposide. As determined by the ability to enhance enzyme-mediated DNA cleavage, quinolone activity towards calf thymus topoisomerase II was enhanced by the presence of a cyclopropyl group at the N-1 ring position and by the presence of a fluorine at C-8. Furthermore, the 4'-hydroxyphenyl substituent at the C-7 position was critical for the potency of CP-115,953 towards the mammalian type II enzyme. In this regard, the aromatic nature of the C-7 ring as well as the presence and the position of the 4'-hydroxyl group contributed greatly to drug activity. Finally, the cytotoxicity of quinolones in the CP-115,953 series towards mammalian cells paralleled the in vitro stimulation of DNA cleavage by topoisomerase II rather than the inhibition of enzyme-catalyzed DNA relaxation. This correlation strongly suggests that these quinolones promote cell death by converting topoisomerase II to a cellular poison.     

Protection of mammalian cells against chemotherapeutic agents thiotepa, 1,3-N,N'-bis(2-chloroethyl)-N-nitrosourea, and mafosfamide using the DNA base excision repair genes Fpg and alpha-hOgg1: implications for protective gene therapy applications

Chemotherapeutic agents used in the treatment of cancer often lead to dose-limiting bone marrow suppression and may initiate secondary leukemia. N,N',N"-triethylenethiophosphoramide (thiotepa), a polyfunctional alkylating agent, is used in the treatment of breast, ovarian, and bladder carcinomas and is also being tested for efficacy in the treatment of central nervous system tumors. Thiotepa produces ring-opened bases such as formamidopyrimidine and 7-methyl-formamidopyrimidine, which can be recognized and repaired by the formamidopyrimidine glycosylase/AP lyase (Fpg) enzyme of Escherichia coli. Using this background information, we have created constructs using the E. coli fpg gene along with the functional equivalent human ortholog alpha-hOgg1. Although protection with the Fpg protein has been previously observed in Chinese hamster ovary cells, we demonstrate significant (100-fold) protection against thiotepa using the E. coli Fpg or the human alpha-hOgg1 cDNA in NIH3T3 cells. We have also observed a 10-fold protection by both the Fpg and alpha-hOgg1 transgenes against 1,3-N,N'-bis(2-chloroethyl)-N-nitrosourea (BCNU) and, to a lesser extent, mafosfamide (2-fold), an active form of the clinical agent cyclophosphamide. These latter two findings are novel and are particularly significant since the added protection was in an O(6)-methylguanine-DNA methyltransferase-positive background. These results support our general approach of using DNA base excision repair genes in gene therapy for cellular protection of normal cells during chemotherapy, particularly against the severe myelosuppressive effect of agents such as thiotepa, BCNU, and cyclophosphamide.     

Will killing the last HIV1 particle cure AIDS patients? II: Second part. Decrease of viral load and of T-suppressor cells, and increase of the cytotoxic cells, without effect on CD4, after the use of 10 virostatics applied in 3 or 4 drug combinations of different sequences. The time for CD4 immunotherapy?

We reported in the first part of this editorial [1] and in an article on AIDS therapy with five HIV₁ virostatics applied in two then three, or initially three, or initially four agent combinations, given in 3 week sequences differing from each other due to drug rotation [2], the contrast between: a) the decrease of viral load, possibly below the detectable level, b) the absence of effect on the helper CD4⁺, the CD8⁺ C57⁻ cytotoxics and the CD8⁺ C57⁺ suppressor cells. We proposed a thesis according to which the HIV₁-AIDS complex might have another pathogenic component other than HIV₁, ie, a microchimerism graft-versus-host reaction (GvH) or an autologous GvH-like reaction [1].Shifting from five to 10 virostatics owing to the availability of lamivudine or 3TC [3], stavudine or d4T [4] and three HIV₁ protease inhibitors, saquinavir [5], ritonavir [6] and indinavir [7], applied according to the same modality, we have enhanced the reduction of viral load, and significantly decreased the CD8⁺ C57⁺ suppressor cell counts, and increased those of the CD8⁺ C57⁻ cytotoxic cells.This result which indirectly shows the role of HIV₁ in the increase of suppressor CD8⁺ cells, hence in the late loss pf immune memory and of opportunistic infections [8], reinforces the thesis of a role, in AIDS pathogenesis, of a latent GvH reaction activated by HIV, primo-infection, and its evolution from the hyperplastic phase to the hypoplastic one, which, inducing severe immune suppression, is responsible for HIV₁ active infection relapse after the so-called latent phase [1].Hence the proposition we make, of an indication of CD4 modulation with non specific immunotherapy by bestatin [9], of which we showed the effect in another population of HIV₁-AIDS complex patients [10]. Its effect can be potentiated by tuftsin [11, 12]. When the suppressor cell number goes up over that of the cytotoxic one after the HIV, active infection relapse, Interferon y could be added, which, by amplifying the CD28 pathway [13] on CD8⁺ cytotoxics, while suppressor cells lack CD28 [14], which might reestablish a ratio of suppressor over cytotoxic cells nearer to normal.It remains that the role of the five secondarily included agents in the decrease of suppressor cells will only be attributed with certainty and entirely to their virostatic effect, if it is shown that none of them exerts a selective anti-suppressor cell action.