分泌型磷脂酶PLA2G5的生物学功能及其抑制剂研究进展

分泌型磷脂酶PLA2G5属于磷脂酶A2超家族的一员,在免疫细胞和非免疫细胞中均有表达.研究表明,PLA2G5参与生物学事件的发生发展,在特定的病理条件下具有诱导作用.本文简要阐述了PLA2G5的来源、结构特征、生物学功能和在疾病中的作用,以及现有或潜在的PLA2G5抑制剂,以期探索基于PLA2G5的治疗新靶标.     

Factors influencing the sensitivity of two human bladder carcinoma cell lines to cis-diamminedichloroplatinum(II)

A two-fold difference in sensitivity to cis-diamminedichloroplatinum(II) (cisplatin), as judged by colony forming assays, has been demonstrated in two human bladder carcinoma continuous cell lines. Approximately twice as many DNA-DNA interstrand cross-links (ISL) and a 2-fold greater inhibition of DNA synthesis occurred in the more sensitive T24 cell line than in the RT112 cell line after exposure to the same concentrations of cisplatin. Equitoxic concentrations of cisplatin resulted in similar extents of ISL and inhibition of DNA synthesis in both cell lines. Although drug uptake was identical, twice as much cisplatin was bound to the DNA of T24 cells than RT112 cells. However after equitoxic concentrations of cisplatin the DNA from both cell lines was platinated to a similar extent. In addition, levels of glutathione (GSH), glutathione reductase (GR) and total glutathione-S-transferases (GST) were higher in the less sensitive RT112 cell line.     

A Note on the Purification of Alcian Blue

Alcian blue 8GX is a copper phthalocyanin dye that shows a high degree of specificity for polyanionic substances such as hyaluronic acid, sialic acid and the chondroitin sulfates. This dye has proved useful for both histochemical and electrophoretic staining of these substances. The Biological Stain Commission has recently begun to certify Alcian blue (Schenk 1981). Commercially available lots contain approximately 50% dye. The remaining constituents have been identified as primarily boric acid, as well as sulfates and dextrins (Scott 1972, Horobin and Goldstein 1972). Horobin and Goldstein (1972) have pointed out that these contaminants may adversely affect staining in the critical electrolyte concentration procedure. Scott (1972), while not ascribing any adverse effects to the presence of boric acid, recommends its removal by differential precipitation with acetone. In this procedure one part of a 2-5% aqueous solution of the dye is added to 5-10 parts of acetone. The precipitated dye is approximately 80% pure. While this method is relatively simple, it does have several drawbacks. Low concentrations of Alcian blue (i.e., 2%) must be used to obtain purities near 80%. Thus a minimum of 250 ml of acetone is needed to purify 1 gram of dye. Furthermore, Horobin and Goldstein (1972) have reported that contamination by dextrin or unknown organic substances (detergent?) interferes with precipitation of the dye enough to make purification by Scott's method impossible. When difficulty in the precipitation of Alcian blue by Scott's method was encountered, the following simple method for the purification of the dye was developed.     

Isopycnography of intact cells — V: The kinetics of the initiation of DNA synthesis in E. coli undergoing nutrient shift-up

Manipulation of the ribosome content of E. coli by means of a nutrient shift-up leads to predictable changes in cellular specific gravity. Thus whole-cell pycnography can be used to monitor the proliferative status of the rRNA loci which cluster closely about the genetic origin of DNA synthesis. In this manner the rate of initiating new rounds of genome replication was followed during an upshift. The results indicate that after a short lag initiation of new rounds abruptly and completely shifts to the rate appropriate to the enriched conditions.     

A comparative binding of platinum anti-tumour compounds to plasma proteins in the rat (in vivo) and mouse (in vitro).

Plasma protein binding of 195mPt-labelled cisplatin, carboplatin and iproplatin has been studied in vivo in rat and in vitro in mouse, using both electrophoresis and trichloroacetic acid precipitation. After intravenous injection plasma clearance rates were biphasic for all 3 compounds, (t1/2 alpha, 13-17 min) but cisplatin was retained thereafter longer than the others. By 5 min, gel electrophoresis showed protein labelling with all 3 drugs but none involved low mol.wt. proteins (< 16 kDa). At 2 h a notable proportion of the protein bound platinum was associated with the latter components. There was a general resemblance between the distribution patterns of cisplatin and carboplatin whereas iproplatin showed a persistent retention of the label with time to higher mol. wt. proteins. From in vitro incubation with mouse plasma, rates of interaction respectively were cisplatin t1/2 alpha, 35 min, beta 8 h, carboplatin t1/2, 44 h and iproplatin t1/2, 104 h. By electrophoresis the protein bound fraction pattern (1 h) was again similar for cisplatin and carboplatin with virtually no binding to low mol. wt. proteins. After 24 h these were now involved to a high degree (40%). Iproplatin showed relatively marked binding to proteins of higher mol. wt. but no transfer with time to the low mol. wt. protein zone. A possible explanation is the need for in vivo metabolism for this compound as manifest in the rat. It is suggested that the significance of interaction with low mol. wt. proteins merits further investigation in relation to the antitumour and toxicological actions of these drugs.     

A proposed mechanism relating the antitumor behavior of cis-platinum amine complexes to their inhibition of a model enzyme

The twenty-four hour inhibition of m-malate dehydrogenase (E.C. 1.1.1.37) by various complexes of cis-platinum(II) and cis-platinum(IV) was measured as a function of the platinum concentration. It was observed that increased alkylation of the amine groups of Pt(II) and to a lesser degree of Pt(IV) decreased the activity consistently. It was also observed that the Pt(IV) analogues inhibit the enzyme to about an order of magnitude greater than the Pt(II) complexes. These phenomena will be interpreted.     

人体动脉血气波浪式变化特点的实验证据—同时间动、静脉血波浪式变化幅度的不同*

目的: 人动脉血来源是右心系统并在肺脏进行气体交换的静脉血,右心系统的静脉血是否存在波浪式信号目前尚没有证据支持,本研究旨在对比同时间动、静脉血中信号的连续变化特点。方法: 选择心功能正常,需要连续监测动脉血流动力学变化的患者6 例,4男2女,年龄（59.00±16.64） 岁,体质量（71.67±10.37）kg,左心射血分数（LVEF）（61.33±2.16)%。患者签署知情同意书后,选择心功能正常需要监测动、静脉血流动力学变化的患者6 例,连续同时桡动脉、颈内静脉逐搏取血,测定PaO₂。选取2个典型呼吸周期,用于分析同时段动、静脉血气的波浪式变化。分别比较患者血氧分压最高和最低值,以验证同时段动、静脉血气是否都存在周期性波浪式信号变化。此外,将患者动脉、静脉血气周期性波浪式信号的变化幅度进行统计学t 检验分析,比较有无差异。结果: 共6例患者,抽取动、静脉血液充满肝素化细长塑化管需要15~16次心跳,即取血需要15~16次心跳,全部覆盖超过2个呼吸周期。所有患者动脉血气中PaO₂均呈现明显的波浪式变化（P<0.05）,幅度是（9.96±5.18）mmHg,是均值的（8.09±2.43）%。患者静脉血气中PaO₂波动幅度并不明显,为（1.63±0.41）mmHg,是均值的（3.91±1.22）%,与动脉血气组相比有明显统计学差异（P<0.05）。结论: 采用同时连续逐搏动、静脉取血血气分析法证实,患者自主呼吸时动脉血气有明显的周期性波浪式变化信号,而静脉血气几乎没有周期性波浪式变化信号（很弱）,说明动脉血气波浪式信号主要是由于肺通气过程中吸气和呼气期产生肺泡中氧分压规律性上升和下降,通过离开肺毛细血管与肺泡氧气压力平衡的动脉化血液,经过左心室搏血进入动脉血管系统所致。     

新生儿首次呼吸前后脐带动静脉血液氧和二氧化碳变化探索呼吸调控机制的初步报告II—同一个新生儿同一时间的脐带动静脉血液氧和二氧化碳分压差值个体化分析*

目的: 为探讨新生儿自主呼吸产生机制,前文已对新生儿出生后自主呼吸开始前脐带动静脉氧气和二氧化碳差值进行了人群组间分析;而本部分则对相关信息进行个体化分析。方法: 在产前经所有胎儿父母签署知情同意书,新生儿出生后还没有呼吸之前在脐带动脉和脐带静脉分别连续逐搏取血,仅有3例同时采集到Pua和Puv血液样本进行血气分析测定,计算分析脐带静脉和脐带动脉的异同和动态变化。结果: 虽然准备了数十产妇,但仅有3例同时采集到Pua和Puv血液样本,同一时间的PuvO₂显著高于PuaO₂（P均<0.01）,平均相差（24.17±7.09） mmHg;而PuvCO₂显著低于PuaCO₂（P均<0.01）,平均相差（-7.67±3.70） mmHg。在同一时间的Puv-uaO₂显著高于Puv-uaCO₂（P<0.05）。结论: 新生儿出生后自主呼吸前,全部氧气供应由脐带静脉运输,只要胎盘开始剥离则新生儿的PuaO₂随时间（心跳次数）逐渐降低,当PuaO₂达到触发呼吸阈值（最低值）诱发第一次吸气开始其自主呼吸。     

Punishment is strongly motivated by revenge and weakly motivated by inequity aversion

There are two broad functional explanations for second-party punishment: fitness-leveling and deterrence. The former suggests that people punish to reduce fitness differences, while the latter suggests that people punish in order to reciprocate losses and deter others from inflicting losses on them in the future. We explore the relative roles of these motivations using a pre-registered, two-player experiment with 2426 US participants from Amazon Mechanical Turk. Participants played as the “responder” and were assigned to either a Take or Augment condition. In the Take condition, the “partner” could steal money from the responder's bonus or do nothing. In the Augment condition, the partner could augment the responder's bonus by giving them money at no cost to themselves or do nothing. We also manipulated the responders' starting endowments, such that after the partner's decision, responders experienced different payoff outcomes: advantageous inequity, equality, or varying degrees of disadvantageous inequity. Responders then decided whether to pay a cost to punish the partner. Punishment was clearly influenced by theft and was most frequent when theft resulted in disadvantageous inequity. However, people also punished in the absence of theft, particularly when confronted with disadvantageous inequity. While the effect of inequity on punishment was small, our results suggest that punishment is motivated by more than just the desire to reciprocate losses. These findings highlight the multiple motivations undergirding punishment and bear directly on functional explanations for the existence of punishment in human societies.