类核沉降法对三个着色性干皮病(XP)家系成员DNA修复能力的测定及杂合子的检出

应用类核沉降法,分析了三个着色性干皮病家系中35名成员外周血淋巴细胞在紫外线(2.5μJ/mm~2)照射和MNNG(2μg/mI)损伤后DNA修复能力。结果表明,6名XP患者和9名杂合子DNA损伤后20小时尚不能完成修复,他们11小时DNA修复率均值分别为UV,0.61±0.13,0.59±0.15和MNNG,0.44±0.15,0.46±0.16,与家系中10名非血缘亲属正常人DNA修复率均值为UV,0.96±0.07,MNNG,0.71±0.07相比,差异非常显著(Ρ<0.01),而XP患者和杂合子DNA修复率则无显著性差异(Γ>0.05)。提示,类核沉降技术可能为XP家系中杂合子成员检出提供一种有希望的方法。     

DNA修复酶系统的研究——Ⅰ.紫外线诱发~3H-TdR在着色性干皮病淋巴细胞中的非合成期掺入

本文报告了用液体闪烁计数方法对5例华东地区的着色性干皮病病人外周血淋巴细胞进行DNA切除修复功能的研究。结果发现,这5例病人淋巴细胞中的DNA切除修复功能都有不同程度的缺陷。3例病人为正常人的50％左右,1例为正常人的15％,1例在正常人的5％以下。作者提出了紫外线诱发淋巴细胞非合成期~3H-TdR掺入指数的大小代表DNA切除修复功能的高低,并根据实验结果与临床资料分析,认为DNA修复的程度与着色性干皮病的病情进展可能存在着直接关系。这与Takebe(1978)的结论是一致的。     

正常人和SLE患者血清中抗DNA抗体的研究

用亲和层析法对6例正常人和4例SLE患者血清中抗DNA抗体进行提取和定量研究,发现正常人血清中抗DNA抗体的组成IgM/IgG大于1,是以IgM为主的抗体,SLE患者血清中抗DNA抗体含量高,IgM/IgG小于1,是以IgG为主的抗体。用胰蛋白酶降解提取的抗DNA抗体再借助于SDS—聚丙烯酰胺凝胶电泳对正常人和SLE患者抗DNA抗体的结构进行初步探讨,电泳结果表明正常人和SLE患者纯化抗DNA抗体经胰蛋白酶降解以后,正常人在52.2Kd区有一特异性降解片段,而SLE患者则在33.6Kd区有明显的降解片段富集,且表明它们是抗DNA—IgG所产生的。这说明SLE患者血清中抗DNA—IgG不仅在数量上比正常人有所增加,而且在结构上也有所不同。此外,这两种不同的抗DNA—IgG被胰蛋白酶降解的速度也有差异。     

正常人淋巴细胞程序外DNA合成的水平

程序外DNA合成(unscheduled DNA synthesis,UDS)反映了细胞对DNA损伤进行切除修复的能力,在毒理学、肿瘤学、放射医学等多种学科中都有应用。关于我国正常人外周血淋巴细胞UDS的水平,仅在近几年才有零星的附带观察,例数都较少,而专文报道,迄今未见。本文报告对60例正常人的观察结果。 1 材料与方法1.1 血液样品来源 本院医护人员(除外放射科     

抗辐射菌中DNA损伤修复主要基因群的研究进展

抗辐射红色球菌对电离辐射具有很高的放射线抵抗性,该菌具有惊人的DNA的二条链切断的修复能力,由辐射等引起的切断损伤DNA在几至十几小时内能高效正确地进行完全修复。在对切断的双链DNA进行修复时,除了大肠杆菌等生物在切断的双链DNA修复时出现的蛋白质以外,还有该菌所特有的修复蛋白质也参与修复。本文对该菌所特有的DNA二条链的切断损伤修复的主要基因及其相互作用进行了简要介绍。     

DNA修复酶系统的研究 Ⅱ.紫外线和丝裂霉素C诱发着色性干皮病外周血淋巴细胞的姐妹染色单体互换的观察

本文报告4例着色性干皮病病人和3例正常人外周血淋巴细胞经紫外线照射和/或丝裂霉素C处理诱发SCE的观察结果。经紫外线照射的3例着色性干皮病病人淋巴细胞的诱发SCE频率比未照射的自发SCE频率均有显著增高(P<0.01),而正常人的淋巴细胞经紫外线照射诱发的SCE频率与未照射的自发SCE频率之间无显著差异(P>0.05)。经丝裂霉素C处理的2例着色性干皮病病人和1例正常人淋巴细胞的诱发SCE频率比未处理的自发SCE频率均有明显增加,但病人的增加幅度显著大于正常人(P<0.01)。结果表明,这4例着色性干皮病病人都存在着DNA切除修复功能缺陷。此外,还发现分离淋巴细胞的自发SCE频率比微量全血培养的显著地高(P<0.01)。     

耐辐射球菌DNA双链断裂修复机制研究新进展

耐辐射球菌对于电离辐射等DNA损伤剂具有极强的抗性,能够将同一个基因组中同时产生的高达100个以上的DNA双链断裂在数十小时内高效而精准地进行修复,是研究DNA双链断裂修复机制的重要模式生物。同源重组、非同源末端连接和单链退火途径作为3个主要的修复途径参与了耐辐射球菌基因组DNA双链断裂的修复过程。此外,一系列新发现的重要蛋白质,如Ppr I、Ddr B等对于耐辐射球菌基因组的修复过程同样至关重要。根据本实验室和国内外在这一研究领域近年来的报道,以不同的修复途径为线索,综述该菌DNA双链断裂修复机制的最新研究成果。     

丙线照射所致人血淋巴细胞与中国白鼠卵巢成纤维细胞DNA单链断裂及其修复的观察

用微孔滤膜碱洗脱法观察了丙线照射引起人血淋巴细胞(D_o为400拉德)及中国仓鼠卵巢成纤维细胞(D_o为200拉德)的DNA单链断裂及其修复。在0～3000拉德范围内,两种细胞DNA单链断裂的程度基本一致,照射剂量与单链断裂的对数之间呈直线相关。800、1500及3000拉德照射后,经过0.5～7小时的孵育,中国仓鼠卵巢成纤维细胞DNA单链断裂的修复优于人血淋巴细胞,说明这两种细胞辐射敏感性与DNA单链断裂修复能力无关。     

丙线照射所致人血淋巴细胞与中国仓鼠卵巢成纤维细胞DNA单链断裂及其修复的观察

用微孔滤膜碱洗脱法观察了丙线照射引起人血淋巴细胞(Do为400拉德)及中国仓鼠卵巢成纤维细胞(Do为200拉德)的DNA单链断裂及其修复。在0—3000拉德范围内,两种细胞DNA单链断裂的程度基本一致,照射剂量与单链断裂的对数之间呈直线相关。800、1500及3000拉德照射后,经过0.5—7小时的孵育,中国仓鼠卵巢成纤维细胞DNA单链断裂的修复优于人血淋巴细胞,说明这两种细胞辐射敏感性DNA单链断裂修复能力无关。     

DNA瞬态损伤的快速修复阻断癌变最早事件的发展

DNA瞬态损伤(DNA自由基)引起DNA碱基对断裂和双螺旋结构下沉,导致基因失稳,可能是构成癌变的最早事件。基因失稳是癌的共同特征标志之一,而DNA修复可通过维持基因完整性来降低癌的发生。修复DNA的能力低下也是癌的共同特征标志之一。近年新发现了一种独特的修复机制,称为快速修复,专一地修复DNA瞬态损伤,只需几个微秒就能完成,比已知的酶性修复快十亿倍,修复速率常数达到109L.mol-1.s-1。还发现凡是具有快速修复能力的植物多酚类几乎都能不同程度地削弱癌的特征标志,包括使癌细胞形态正常化、抑制癌细胞增殖、促进癌细胞分化或凋亡、降低端粒酶活性、减少植瘤率、阻止细胞迁移和扩散、抑制血管生成、延长存活时间、降低患癌风险等。     

白蚁与动物及微生物的共生类型及其机制

综述了白蚁螱客的主要种类、共生关系及相关机制的研究进展。白蚁螱客中,已报道的动物种类达170种。在与动物的共生关系中存在偏利共生（宾主共栖和异种共栖）、互利共生和无关共生三种;在与微生物的共生关系中,存在与内生菌（原生动物、细菌、真菌和放线菌）和外生菌（蚁巢伞菌等）间的互利关系。指出了白蚁与螱客研究中存在的问题,给出了解决方案,并提出了今后可能的研究热点或方向,为白蚁的综合利用（如纤维素酶）及今后研究物种间的协同进化提供了基础资料。     

New amino-dithiaphospholanes and phosphoramidodithioites and their rhodium and iridium complexes

New sulfur derivatives of phosphoramidite ligands were synthesized and the impact of the sulfur unit on the spectroscopic properties of their rhodium and iridium complexes was investigated. The new ligands Bn₂NPSCH₂CH₂S^a(P-S^a) (Bn = benzyl, 4), Bn₂NPSCHCHS^a(CH₂)₃C^aH₂(P-S^a)(C^a-S^a) (6) and Bn₂NP(4-XC₆H₄OMe)₂ (X = S, 7a; X = O, 7b) were converted to the rhodium and iridium complexes trans-[Rh(CO)Cl(L)₂] (L = 4, 6, 7), [RhCl(COD)(L)] (L = 4, 6, 7), [IrCl(COD)(7a)] and [IrCl₂Cp∗(6)]. For comparison, some phosphoramidite complexes of these formulations also were synthesized. The new metal complexes were spectroscopically analyzed. For the carbonyl complexes, the ν_CO IR stretching frequencies were lower than for the corresponding phosphite and phosphoramidite ligands. The ¹J_PRh coupling constants for the rhodium complexes with the new ligands were also smaller than for the respective phosphoramidite and phosphite complexes. Finally, the ¹J_PSe coupling constants of the selenides of the new ligands were lower than those of the phosphoramidite ligands but higher than for PPh₃. The spectroscopic data reveal that the new thio ligands 4, 6 and 7a are more electron donating than phosphites and phosphoramidites but less electron donating than PPh₃.     

Astrocytes and Synaptosomes Transport and Metabolize Lactate and Acetate Differently

Astrocytes transport the monocarboxylate acetate, but synaptosomes do not. The reason for this is unknown, because both preparations express monocarboxylate transporters (MCT). The transport and metabolism of lactate, another monocarboxylate, was examined in these two preparations, and the results were compared to those for acetate. Lactate transport is more rapid in astrocytes than in synaptosomes, but of lower affinity (Kms of 17 and 4 mM, respectively). Lactate (0.2 mM) is metabolized to CO2 more rapidly in synaptosomes than in astrocytes (rates of 0.37 and 0.07 nmol x mg protein(-1) x min(-1), respectively). The reason for this is unclear, but cellular differences in lactate dehydrogenase isotype expression may be involved. Acetate is metabolized to CO2 more rapidly in astrocytes than in synaptosomes (rates of 0.43 and 0.02 nmol x mg protein(-1) x min(-1), respectively). This is likely due to cellular differences in the expression of monocarboxylate transporter subtypes.     

Rapporteur report: Basics and technology and metrology and standards

The first and second sessions of the Workshop focussed on the basics of ultrasound and infrasound, their applications in both industry and medicine, and metrology and protection standards for ultrasound applications.     

Relative and combined effects of ethanol and protein deficiency on strontium and barium bone content and fecal and urinary excretion

To elucidate accumulation of minerals in human iliac arteries with aging, the content of minerals was analyzed by inductively coupled plasma atomic emission spectrometry. Bilateral common, internal, and external iliac arteries of 16 men and 8 women, ranging ages from 65 to 93 yr, were examined. It was found that an extremely high accumulation of calcium and phosphorus occurred in the common iliac artery at old age, being higher than that of the internal and external iliac arteries. It should be noted that the accumulation of calcium and phosphorus is the highest in the common iliac artery among the human arteries examined to date. Regarding sexual differences, the content of calcium and phosphorus in the common and internal iliac arteries was higher in women than in men, whereas their content in the external iliac artery was lower in women than in men.     

Prostaglandin and thromboxane production by human and guinea-pig macrophages and leucocytes

The ability of partially purified human and guinea-pig haematogenous cell populations, when cultured in vitro, to metabolise arachidonic acid (AA) has been studied. Supernatants from 24 hour cell culture have been subjected to analysis for products of AA metabolism by gas chromatography with electron-capture detection.The cell types studied were human peripheral blood monocytes (both glass adherent and non-adherent), neutrophils, eosinophils and leukemic leucocytes; thoracic duct lymphocytes and lung alveolar macrophages. From the guinea-pig, induced and non-induced macrophage or neutrophil enriched peritoneal exudate populations, lymph node cells, peritoneal eosinophils and peripheral blood platelets were examined. Supernatants were assayed for the presence of PGE₂, PGD₂, PGF_2α, TXB₂ and 6-keto-PGF_1α. In all types studied PGE₂ and TXB₂ were the major products formed. The identification of PGE₂ and TXB₂ was confirmed by GC/MS with multiple ion monitoring.The results have been compared with other reports and their possible significance discussed in relation to the proposed role of prostaglandins as mediators and modulators in immunopathology.     

Chemokines and cytokines: axis and allies in asthma and allergy

Allergic asthma can be precipitated by many factors. For the atopic person, fungus, pollen, dust mites, cockroach antigens, and diesel exhaust are all agents that may trigger an allergic attack. Cytokines and chemokines are integral mediators of fungal asthma. From the earliest time points, they recruit and activate the cells required for the clearance of fungus as well as being critical factors involved in the immunopathology of this disease. In the final analysis, it is clear that these mediators can act to the benefit or the detriment of the host.     

Oxidation and nitration of ribonuclease and lysozyme by peroxynitrite and myeloperoxidase

In spite of the many studies on protein modifications by reactive species, knowledge about the products resulting from the oxidation of protein-aromatic residues, including protein-derived radicals and their stable products, remains limited. Here, we compared the oxidative modifications promoted by peroxynitrite and myeloperoxidase/hydrogen peroxide/nitrite in two model proteins, ribonuclease (6Tyr) and lysozyme (3Tyr/6Trp). The formation of protein-derived radicals and products was higher at pH 5.4 and 7.4 for myeloperoxidase and peroxynitrite, respectively. The main product was 3-nitro-Tyr for both proteins and oxidants. Lysozyme rendered similar yields of nitro-Trp, particularly when oxidized by peroxynitrite. Hydroxylated and dimerized products of Trp and Tyr were also produced, but in lower yields. Localization of the main modified residues indicates that peroxynitrite decomposes to radicals within the proteins behaving less specifically than myeloperoxidase. Nitrogen dioxide is emphasized as an important protein modifier.