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来源：彩612023-06-30 17:48

科学家找到可能触发阿尔兹海默症记忆衰退“机关”******

　　科技日报讯 (记者刘园园)记者1月15日从西湖大学获悉，该校施一公团队历经8年探索，在阿尔兹海默症领域取得重要发现——他们找到了可能触发阿尔兹海默症记忆衰退的“机关”。这一发现对理解阿尔兹海默症的发病机制，以及开展针对性的药物设计，具有重要意义。相关研究结果日前在线发表于《细胞研究》。

　　“阿尔兹海默症，俗称老年痴呆症，记忆衰退是这种疾病最显著的临床表现之一。”本文共同第一作者、西湖大学生命科学学院博士后周家耀说，阿尔兹海默症的原理和机制迄今尚未明确。

　　随着基因测序技术的发展，科学家发现，APOE4是阿尔兹海默症最大的风险基因。APOE蛋白是人体载脂蛋白之一，在人群中有APOE2、APOE3和APOE4这3种亚型。研究发现，APOE2的携带者，不易患阿尔兹海默症；而APOE4的携带者，患病风险成倍增加。因此，找到APOE4的受体可能是破解阿尔兹海默症的关键。

　　此前研究发现，小胶质细胞对神经突触的剪切功能会在阿尔兹海默症患者中被异常激活，从而导致患者失忆。而小胶质细胞能否执行功能，可能与LilrB蛋白有关。

　　APOE蛋白与LilrB蛋白之间是否存在某种联系？这或许是破解阿尔兹海默症发病机制的重要线索。

　　“在大量研究基础上，我们建立起新猜测：LilrB家族蛋白和APOE蛋白有相互作用，并且只和APOE4结合而不与APOE2结合。”周家耀解释说，这一猜想如成立，或有可能解释阿尔兹海默症的生物化学原理：APOE4与LilrB蛋白结合，激活小胶质细胞，导致神经突触被剪切，进而导致记忆衰退并引发阿尔兹海默症。

　　为验证新猜想，研究团队开展了一系列实验，系统研究了LilrB人源家族的5个同源蛋白和3个APOE亚型之间的相互作用。结果正如预期：APOE4与LilrB3可以结合，APOE3结合较弱，而APOE2几乎完全不结合。他们还进一步证实了小胶质细胞因为这种结合而“苏醒”的事实，即APOE4与LilrB3结合后，会激活小胶质细胞。

　　“这项研究找到了阿尔兹海默症患者记忆衰退的机制，为人类对付阿尔兹海默症带来一线曙光。”周家耀介绍，接下来，研究团队将在该成果基础之上，继续开展阿尔兹海默症相关研究，并着眼于阿尔兹海默症的药物研发。

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中新网评：美国众议长选举“连续剧”暴露美式民主痼疾******

　　中新网北京1月9日电(蒋鲤)在15轮投票表决后，美国众议院议长选举这场“连续剧”终于落下帷幕，众议院共和党领袖凯文•麦卡锡最终成功当选第55任美国众议院议长。这是美国国会过去164年来耗时最久的一次议长选举记录，将美国“对抗式民主”的弊端暴露无遗。

资料图：美国众议院共和党领袖麦卡锡。中新社记者沙晗汀摄

　　由于两党对立加剧、党派内斗、利益分配不均等因素，众议长选举陷入一场拉锯战。在此次众议长竞选中，美国民主党议员继续抱团，多轮投票中，一票不投麦卡锡，共和党右翼“强硬派”领头的约20人小团体也拒绝投票麦卡锡。

　　麦卡锡的当选之路一波三折，除了本人的“政治投机派”角色在国会不受欢迎外，与共和党内部政治分歧关系密切。

　　一方面，共和党党内反对者认为，麦卡锡对民主党态度过于软弱，无力对抗民主党控制的参议院和拜登政府，另一方面，因为共和党的多数优势微弱，党内一些影响力较小的派系的政治力量则被放大，有利于他们巩固自己的选票。

　　此外，党内反对者也认为，自己的选票没有换取更多利益，希望以此作为筹码换取麦卡锡更大的让步，比如让他们获得众议院重要委员会中的职务。

　　作为仅次于美国总统、副总统的政坛三号人物，众议院议长通常由众议院多数党领袖担任，选举几乎没有悬念。然而，麦卡锡此次为当选，不得不做出多个关键让步，其中可能包括恢复一项罢黜议长动议机制，使得众议长的权力被削弱，难以掌控众议院。

　　美国有线电视新闻网CNN称，麦卡锡在这场不合时宜的政治勒索中作出让步，这种绥靖政策只会让极端主义势力更加强大。

　　这场引发全世界围观的尴尬选举暴露出美国政治存在严重的对立和分化。在权力博弈思维的裹挟下，党派利益凌驾于国家和人民利益之上，美国两党相互拆台，陷入“为反对而反对”的无脑对垒。而即便是一党内，也会因为利益分配问题产生不同的小派系，相互对抗，选票变成了谋利益的工具。

　　从国会山骚乱到打破记历史记录的15轮众议长选举，“对抗式民主”让美国政治陷入瓶颈，长期对抗势必会让政客们丧失客观公正的判断能力，其政治阶层是否有能力治理国家也会引发质疑。

　　两党之争和党派内斗进一步放大了美国政治体制弊病，美国所谓的“民主”形象，让全世界大跌眼镜。鼓吹以选民利益为先的美式选举，变成了政客们利益置换的游戏，进一步彰显出美国“民主政治”日渐失能，不断极化的党争已使美国政治制度陷入死循环。

　　House speaker election reveals deep-rooted problems in U.S. democracy

　　(ECNS) -- The Republican leader Kevin McCarthy was elected as the 55th speaker of the U.S. House of Representatives after 15 ballots. As the most grueling House speaker election in the past 164 years, the election has highlighted the defects of the country’s "confrontational democracy".

　　The election once reached a stalemate due to intense partisan strife, inner-party struggle among the Republicans, uneven distribution of interests, and more. Democratic Party members forged a close alliance, refusing to vote for McCarthy, while about 20 Republicans also declined to cast ballots for the GOP leader.

　　Except for his unpopular role as a "political speculator" in Congress, McCarthy’s hard-won election can be attributed to turmoil within the Republican Party.

　　On the one hand, opponents in the Republican Party believe that the GOP leader's attitude toward the Democrats is too weak to confront the Senate controlled by Democrats and the Biden administration.

　　On the other hand, the political power of some less influential factions in the Republican Party has been amplified due to the Party’s weak majority advantage in the House of Representatives, which is conducive to consolidating their ticket warehouses.

　　Meanwhile, these opponents believe that their votes failed to win them more benefits, hoping to use this as a bargaining chip for McCarthy's further concessions, such as getting them positions in important House Committees.

　　As the third political figure after the President and Vice President of the U.S., the speaker, by tradition, is the head of the majority party in the House of Representatives.

　　But McCarthy has made many concessions in order to bring the ultra conservatives along, involving what’s known as the “motion to vacate,” a mechanism by which members can force a vote to depose the speaker. The reported concessions will empower individual members at the expense of McCarthy’s sway as speaker.

　　CNN thought the concessions he made during this unseemly political shakedown would only make the extremist faction more powerful.

　　This embarrassing election, which has drawn global attention, exposed the serious opposition and polarization in American politics. Both Democrats and Republicans put their interests before that of the country and its people, attacking and opposing each other irrationally.

　　Besides, different factions arise within a single party and confront each other because of the distribution of interests. Votes have become a tool to win more benefits.

　　From Capitol riots to the House Speaker election with record-breaking ballots, "confrontational democracy" has become a bottleneck of American politics. Long-term confrontation will surely impede politicians to think objectively and fairly while their capacity of governing the country will also raise doubts among the public.

　　Both parties’ struggle and infighting among the Republicans have further amplified the defects of the American political system, with its "democratic" image shocking the world.

　　The U.S.-style election, which advocates putting voters' interests first, has become a game of interest exchange among politicians. In addition, it further demonstrates the malfunction of American "democratic politics" and the constantly polarized party struggle that has trapped the American political system into an infinite cycle.